libgo: update to go1.7rc3

    
    Reviewed-on: https://go-review.googlesource.com/25150

From-SVN: r238662

1155 files changed, 51785 insertions, 16624 deletions

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 7e8d9d4b441..99a68baee78 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-4c88f31a83ca28963d29d6dc9fcdb2e9b093610c
+b156d71ad75a1b73d0ed805a5370a297648d9270
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/libgo/MERGE b/libgo/MERGE
index a40967cea24..dc6e3799770 100644
--- a/libgo/MERGE
+++ b/libgo/MERGE
@@ -1,4 +1,4 @@
-f5cf5673590a68c55b2330df9dfcdd6fac75b893
+8707f31c0abc6b607014e843b7cc188b3019daa9
 
 The first line of this file holds the git revision number of the
 last merge done from the master library sources.
diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index bae3634cff5..7801290d263 100644
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -111,6 +111,7 @@ endif
 toolexeclibgo_DATA = \
 	bufio.gox \
 	bytes.gox \
+	context.gox \
 	crypto.gox \
 	encoding.gox \
 	errors.gox \
@@ -315,6 +316,7 @@ toolexeclibgonethttp_DATA = \
 	net/http/cookiejar.gox \
 	net/http/fcgi.gox \
 	net/http/httptest.gox \
+	net/http/httptrace.gox \
 	net/http/httputil.gox \
 	net/http/pprof.gox
 
@@ -593,6 +595,9 @@ go_bytes_files = \
 go_bytes_c_files = \
 	go/bytes/indexbyte.c
 
+go_context_files = \
+	go/context/context.go
+
 go_crypto_files = \
 	go/crypto/crypto.go
 
@@ -776,15 +781,19 @@ if LIBGO_IS_LINUX
 go_net_interface_file = go/net/interface_linux.go
 else
 if LIBGO_IS_NETBSD
-go_net_interface_file = go/net/interface_netbsd.go
+go_net_interface_file = go/net/interface_bsdvar.go
 else
 if LIBGO_IS_DRAGONFLY
-go_net_interface_file = go/net/interface_dragonfly.go
+go_net_interface_file = go/net/interface_bsdvar.go
+else
+if LIBGO_IS_OPENBSD
+go_net_interface_file = go/net/interface_bsdvar.go
 else
 go_net_interface_file = go/net/interface_stub.go
 endif
 endif
 endif
+endif
 
 if LIBGO_IS_LINUX
 go_net_cloexec_file = go/net/sock_cloexec.go go/net/hook_cloexec.go
@@ -845,6 +854,7 @@ go_net_common_files = \
 	go/net/nss.go \
 	go/net/parse.go \
 	go/net/pipe.go \
+	go/net/port.go \
 	go/net/fd_poll_runtime.go \
 	go/net/port_unix.go \
 	$(go_net_sendfile_file) \
@@ -991,6 +1001,20 @@ endif
 endif
 endif
 
+if LIBGO_IS_LINUX
+go_os_wait_file = go/os/wait_waitid.go
+else
+if LIBGO_IS_DARWIN
+go_os_wait_file = go/os/wait_waitid.go
+else
+if LIBGO_IS_FREEBSD
+go_os_wait_file = go/os/wait_wait6.go
+else
+go_os_wait_file = go/os/wait_unimp.go
+endif
+endif
+endif
+
 go_os_files = \
 	$(go_os_dir_file) \
 	go/os/dir.go \
@@ -1016,7 +1040,8 @@ go_os_files = \
 	$(go_os_sys_file) \
 	$(go_os_cloexec_file) \
 	go/os/types.go \
-	go/os/types_unix.go
+	go/os/types_unix.go \
+	$(go_os_wait_file)
 
 go_path_files = \
 	go/path/match.go \
@@ -1048,6 +1073,7 @@ go_runtime_files = \
 	go/runtime/error.go \
 	go/runtime/extern.go \
 	go/runtime/mem.go \
+	go/runtime/symtab.go \
 	version.go
 
 version.go: s-version; @true
@@ -1134,6 +1160,7 @@ go_testing_files = \
 	go/testing/benchmark.go \
 	go/testing/cover.go \
 	go/testing/example.go \
+	go/testing/match.go \
 	go/testing/testing.go
 
 go_time_files = \
@@ -1174,6 +1201,7 @@ endif
 
 go_archive_tar_files = \
 	go/archive/tar/common.go \
+	go/archive/tar/format.go \
 	go/archive/tar/reader.go \
 	go/archive/tar/stat_unix.go \
 	go/archive/tar/writer.go \
@@ -1192,8 +1220,9 @@ go_compress_bzip2_files = \
 	go/compress/bzip2/move_to_front.go
 
 go_compress_flate_files = \
-	go/compress/flate/copy.go \
 	go/compress/flate/deflate.go \
+	go/compress/flate/deflatefast.go \
+	go/compress/flate/dict_decoder.go \
 	go/compress/flate/huffman_bit_writer.go \
 	go/compress/flate/huffman_code.go \
 	go/compress/flate/inflate.go \
@@ -1225,7 +1254,8 @@ go_crypto_aes_files = \
 	go/crypto/aes/block.go \
 	go/crypto/aes/cipher.go \
 	go/crypto/aes/cipher_generic.go \
-	go/crypto/aes/const.go
+	go/crypto/aes/const.go \
+	go/crypto/aes/modes.go
 go_crypto_cipher_files = \
 	go/crypto/cipher/cbc.go \
 	go/crypto/cipher/cfb.go \
@@ -1257,8 +1287,12 @@ go_crypto_md5_files = \
 if LIBGO_IS_LINUX
 crypto_rand_file = go/crypto/rand/rand_linux.go
 else
+if LIBGO_IS_OPENBSD
+crypto_rand_file = go/crypto/rand/rand_openbsd.go
+else
 crypto_rand_file =
 endif
+endif
 
 go_crypto_rand_files = \
 	go/crypto/rand/eagain.go \
@@ -1280,10 +1314,12 @@ go_crypto_sha1_files = \
 	go/crypto/sha1/sha1block_generic.go
 go_crypto_sha256_files = \
 	go/crypto/sha256/sha256.go \
-	go/crypto/sha256/sha256block.go
+	go/crypto/sha256/sha256block.go \
+	go/crypto/sha256/sha256block_generic.go
 go_crypto_sha512_files = \
 	go/crypto/sha512/sha512.go \
-	go/crypto/sha512/sha512block.go
+	go/crypto/sha512/sha512block.go \
+	go/crypto/sha512/sha512block_generic.go
 go_crypto_subtle_files = \
 	go/crypto/subtle/constant_time.go
 go_crypto_tls_files = \
@@ -1375,7 +1411,10 @@ go_debug_macho_files = \
 	go/debug/macho/macho.go
 go_debug_pe_files = \
 	go/debug/pe/file.go \
-	go/debug/pe/pe.go
+	go/debug/pe/pe.go \
+	go/debug/pe/section.go \
+	go/debug/pe/string.go \
+	go/debug/pe/symbol.go
 go_debug_plan9obj_files = \
 	go/debug/plan9obj/file.go \
 	go/debug/plan9obj/plan9obj.go
@@ -1517,6 +1556,87 @@ go_go_internal_gccgoimporter_files = \
 	go/go/internal/gccgoimporter/importer.go \
 	go/go/internal/gccgoimporter/parser.go
 
+go_golang_org_x_net_http2_hpack_files = \
+	go/golang_org/x/net/http2/hpack/encode.go \
+	go/golang_org/x/net/http2/hpack/hpack.go \
+	go/golang_org/x/net/http2/hpack/huffman.go \
+	go/golang_org/x/net/http2/hpack/tables.go
+
+go_golang_org_x_net_lex_httplex_files = \
+	go/golang_org/x/net/lex/httplex/httplex.go
+
+if LIBGO_IS_BSD
+
+if LIBGO_IS_DARWIN
+x_net_route_files =
+	go/golang_org/x/net/route/interface_classic.go \
+	go/golang_org/x/net/route/interface_multicast.go \
+	go/golang_org/x/net/route/route_classic.go \
+	go/golang_org/x/net/route/sys_darwin.go \
+	go/golang_org/x/net/route/zsys_darwin.go
+endif
+if LIBGO_IS_DRAGONFLY
+x_net_route_files =
+	go/golang_org/x/net/route/interface_announce.go \
+	go/golang_org/x/net/route/interface_classic.go \
+	go/golang_org/x/net/route/interface_multicast.go \
+	go/golang_org/x/net/route/route_classic.go \
+	go/golang_org/x/net/route/sys_dragonfly.go \
+	go/golang_org/x/net/route/zsys_dragonfly.go
+endif
+if LIBGO_IS_FREEBSD
+if LIBGO_IS_386
+x_net_route_freebsd_file =
+	go/golang_org/x/net/route/zsys_freebsd_386.go
+endif
+if LIBGO_IS_X86_64
+x_net_route_freebsd_file =
+	go/golang_org/x/net/route/zsys_freebsd_amd64.go
+endif
+if LIBGO_IS_ARM
+x_net_route_freebsd_file =
+	go/golang_org/x/net/route/zsys_freebsd_arm.go
+endif
+x_net_route_files =
+	go/golang_org/x/net/route/interface_announce.go \
+	go/golang_org/x/net/route/interface_freebsd.go \
+	go/golang_org/x/net/route/interface_multicast.go \
+	go/golang_org/x/net/route/route_classic.go \
+	go/golang_org/x/net/route/sys_freebsd.go \
+	$(x_net_route_freebsd_file)
+endif
+if LIBGO_IS_NETBSD
+x_net_route_files =
+	go/golang_org/x/net/route/interface_announce.go \
+	go/golang_org/x/net/route/interface_classic.go \
+	go/golang_org/x/net/route/route_classic.go \
+	go/golang_org/x/net/route/sys_netbsd.go \
+	go/golang_org/x/net/route/zsys_netbsd.go
+endif
+if LIBGO_IS_OPENBSD
+x_net_route_files =
+	go/golang_org/x/net/route/route_openbsd.go \
+	go/golang_org/x/net/route/sys_openbsd.go \
+	go/golang_org/x/net/route/zsys_openbsd.go
+endif
+
+go_golang_org_x_net_route_files = \
+	go/golang_org/x/net/route/address.go \
+	go/golang_org/x/net/route/binary.go \
+	go/golang_org/x/net/route/interface.go \
+	go/golang_org/x/net/route/message.go \
+	go/golang_org/x/net/route/route.go \
+	go/golang_org/x/net/route/syscall.go \
+	go/golang_org/x/net/route/sys.go \
+	$(x_net_route_files)
+
+golang_org_x_net_route_lo = \
+	golang_org/x/net/route/route.lo
+golang_org_x_net_route_check = \
+	golang_org/x/net/route/check
+
+endif
+
 go_hash_adler32_files = \
 	go/hash/adler32/adler32.go
 go_hash_crc32_files = \
@@ -1576,11 +1696,8 @@ go_index_suffixarray_files = \
 	go/index/suffixarray/qsufsort.go \
 	go/index/suffixarray/suffixarray.go
 
-go_internal_golang_org_x_net_http2_hpack_files = \
-	go/internal/golang.org/x/net/http2/hpack/encode.go \
-	go/internal/golang.org/x/net/http2/hpack/hpack.go \
-	go/internal/golang.org/x/net/http2/hpack/huffman.go \
-	go/internal/golang.org/x/net/http2/hpack/tables.go
+go_internal_nettrace_files = \
+	go/internal/nettrace/nettrace.go
 go_internal_race_files = \
 	go/internal/race/doc.go \
 	go/internal/race/norace.go
@@ -1603,15 +1720,23 @@ else
 if LIBGO_IS_MIPS64
 internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_mips64x.go
 else
+if LIBGO_IS_S390X
+internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_s390x.go
+else
 internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_generic.go
 endif
 endif
 endif
 endif
 endif
+endif
+else
+if LIBGO_IS_OPENBSD
+internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getentropy_openbsd.go
 else
 internal_syscall_unix_getrandom_files =
 endif
+endif
 
 go_internal_syscall_unix_files = \
 	go/internal/syscall/unix/dummy.go \
@@ -1621,6 +1746,7 @@ go_internal_testenv_files = \
 	go/internal/testenv/testenv.go
 go_internal_trace_files = \
 	go/internal/trace/goroutines.go \
+	go/internal/trace/order.go \
 	go/internal/trace/parser.go
 
 go_io_ioutil_files = \
@@ -1684,8 +1810,8 @@ go_net_http_files = \
 	go/net/http/fs.go \
 	go/net/http/h2_bundle.go \
 	go/net/http/header.go \
+	go/net/http/http.go \
 	go/net/http/jar.go \
-	go/net/http/lex.go \
 	go/net/http/method.go \
 	go/net/http/request.go \
 	go/net/http/response.go \
@@ -1718,10 +1844,13 @@ go_net_http_fcgi_files = \
 	go/net/http/fcgi/child.go \
 	go/net/http/fcgi/fcgi.go
 go_net_http_httptest_files = \
+	go/net/http/httptest/httptest.go \
 	go/net/http/httptest/recorder.go \
 	go/net/http/httptest/server.go
 go_net_http_pprof_files = \
 	go/net/http/pprof/pprof.go
+go_net_http_httptrace_files = \
+	go/net/http/httptrace/trace.go
 go_net_http_httputil_files = \
 	go/net/http/httputil/dump.go \
 	go/net/http/httputil/httputil.go \
@@ -1768,15 +1897,18 @@ go_os_signal_files = \
 
 if LIBGO_IS_SOLARIS
 os_user_decls_file = go/os/user/decls_solaris.go
+os_user_listgroups_file = go/os/user/listgroups_solaris.go
 else
 os_user_decls_file = go/os/user/decls_unix.go
+os_user_listgroups_file = go/os/user/listgroups_unix.go
 endif
 
 go_os_user_files = \
 	go/os/user/lookup.go \
 	go/os/user/lookup_unix.go \
 	go/os/user/user.go \
-	$(os_user_decls_file)
+	$(os_user_decls_file) \
+	$(os_user_listgroups_file)
 
 go_path_filepath_files = \
 	go/path/filepath/match.go \
@@ -2147,6 +2279,7 @@ libgo_go_objs = \
 	bufio.lo \
 	bytes.lo \
 	bytes/index.lo \
+	context.lo \
 	crypto.lo \
 	encoding.lo \
 	errors.lo \
@@ -2242,6 +2375,9 @@ libgo_go_objs = \
 	go/scanner.lo \
 	go/token.lo \
 	go/types.lo \
+	golang_org/x/net/http2/hpack.lo \
+	golang_org/x/net/lex/httplex.lo \
+	$(golang_org_x_net_route_lo) \
 	hash/adler32.lo \
 	hash/crc32.lo \
 	hash/crc64.lo \
@@ -2250,6 +2386,7 @@ libgo_go_objs = \
 	net/http/cookiejar.lo \
 	net/http/fcgi.lo \
 	net/http/httptest.lo \
+	net/http/httptrace.lo \
 	net/http/httputil.lo \
 	net/http/internal.lo \
 	net/http/pprof.lo \
@@ -2261,7 +2398,7 @@ libgo_go_objs = \
 	image/jpeg.lo \
 	image/png.lo \
 	index/suffixarray.lo \
-	internal/golang.org/x/net/http2/hpack.lo \
+	internal/nettrace.lo \
 	internal/race.lo \
 	internal/singleflight.lo \
 	internal/syscall/unix.lo \
@@ -2460,6 +2597,15 @@ bytes/check: $(CHECK_DEPS)
 	@$(CHECK)
 .PHONY: bytes/check
 
+@go_include@ context.lo.dep
+context.lo.dep: $(go_context_files)
+	$(BUILDDEPS)
+context.lo: $(go_context_files)
+	$(BUILDPACKAGE)
+context/check: $(CHECK_DEPS)
+	@$(CHECK)
+.PHONY: context/check
+
 @go_include@ crypto.lo.dep
 crypto.lo.dep: $(go_crypto_files)
 	$(BUILDDEPS)
@@ -3275,6 +3421,35 @@ go/internal/gccgoimporter/check: $(CHECK_DEPS)
 	@$(CHECK)
 .PHONY: go/internal/gccgoimporter/check
 
+@go_include@ golang_org/x/net/http2/hpack.lo.dep
+golang_org/x/net/http2/hpack.lo.dep: $(go_golang_org_x_net_http2_hpack_files)
+	$(BUILDDEPS)
+golang_org/x/net/http2/hpack.lo: $(go_golang_org_x_net_http2_hpack_files)
+	$(BUILDPACKAGE)
+golang_org/x/net/http2/hpack/check: $(CHECK_DEPS)
+	@$(CHECK)
+.PHONY: golang_org/x/net/http2/hpack/check
+
+@go_include@ golang_org/x/net/lex/httplex.lo.dep
+golang_org/x/net/lex/httplex.lo.dep: $(go_golang_org_x_net_lex_httplex_files)
+	$(BUILDDEPS)
+golang_org/x/net/lex/httplex.lo: $(go_golang_org_x_net_lex_httplex_files)
+	$(BUILDPACKAGE)
+golang_org/x/net/lex/httplex/check: $(CHECK_DEPS)
+	@$(CHECK)
+.PHONY: golang_org/x/net/lex/httplex/check
+
+if LIBGO_IS_BSD
+@go_include@ golang_org/x/net/route.lo.dep
+golang_org/x/net/route.lo.dep: $(go_golang_org_x_net_route_files)
+	$(BUILDDEPS)
+golang_org/x/net/route.lo: $(go_golang_org_x_net_route_files)
+	$(BUILDPACKAGE)
+golang_org/x/net/route/check: $(CHECK_DEPS)
+	@$(CHECK)
+endif
+.PHONY: golang_org/x/net/route/check
+
 @go_include@ hash/adler32.lo.dep
 hash/adler32.lo.dep: $(go_hash_adler32_files)
 	$(BUILDDEPS)
@@ -3383,14 +3558,14 @@ index/suffixarray/check: $(CHECK_DEPS)
 	@$(CHECK)
 .PHONY: index/suffixarray/check
 
-@go_include@ internal/golang.org/x/net/http2/hpack.lo.dep
-internal/golang.org/x/net/http2/hpack.lo.dep: $(go_internal_golang_org_x_net_http2_hpack_files)
+@go_include@ internal/nettrace.lo.dep
+internal/nettrace.lo.dep: $(go_internal_nettrace_files)
 	$(BUILDDEPS)
-internal/golang.org/x/net/http2/hpack.lo: $(go_internal_golang_org_x_net_http2_hpack_files)
+internal/nettrace.lo: $(go_internal_nettrace_files)
 	$(BUILDPACKAGE)
-internal/golang.org/x/net/http2/hpack/check: $(CHECK_DEPS)
+internal/nettrace/check: $(CHECK_DEPS)
 	@$(CHECK)
-.PHONY: internal/golang.org/x/net/http2/hpack/check
+.PHONY: internal/nettrace/check
 
 @go_include@ internal/race.lo.dep
 internal/race.lo.dep: $(go_internal_race_files)
@@ -3593,6 +3768,15 @@ net/http/httptest/check: $(check_deps)
 	@$(CHECK)
 .PHONY: net/http/httptest/check
 
+@go_include@ net/http/httptrace.lo.dep
+net/http/httptrace.lo.dep: $(go_net_http_httptrace_files)
+	$(BUILDDEPS)
+net/http/httptrace.lo: $(go_net_http_httptrace_files)
+	$(BUILDPACKAGE)
+net/http/httptrace/check: $(check_deps)
+	@$(CHECK)
+.PHONY: net/http/httptrace/check
+
 @go_include@ net/http/httputil.lo.dep
 net/http/httputil.lo.dep: $(go_net_http_httputil_files)
 	$(BUILDDEPS)
@@ -3833,6 +4017,8 @@ bufio.gox: bufio.lo
 	$(BUILDGOX)
 bytes.gox: bytes.lo
 	$(BUILDGOX)
+context.gox: context.lo
+	$(BUILDGOX)
 crypto.gox: crypto.lo
 	$(BUILDGOX)
 encoding.gox: encoding.lo
@@ -4027,6 +4213,17 @@ go/internal/gcimporter.gox: go/internal/gcimporter.lo
 go/internal/gccgoimporter.gox: go/internal/gccgoimporter.lo
 	$(BUILDGOX)
 
+golang_org/x/net/http2/hpack.gox: golang_org/x/net/http2/hpack.lo
+	$(BUILDGOX)
+
+golang_org/x/net/lex/httplex.gox: golang_org/x/net/lex/httplex.lo
+	$(BUILDGOX)
+
+if LIBGO_IS_BSD
+golang_org/x/net/route.gox: golang_org/x/net/route.lo
+	$(BUILDGOX)
+endif
+
 hash/adler32.gox: hash/adler32.lo
 	$(BUILDGOX)
 hash/crc32.gox: hash/crc32.lo
@@ -4055,7 +4252,7 @@ image/color/palette.gox: image/color/palette.lo
 index/suffixarray.gox: index/suffixarray.lo
 	$(BUILDGOX)
 
-internal/golang.org/x/net/http2/hpack.gox: internal/golang.org/x/net/http2/hpack.lo
+internal/nettrace.gox: internal/nettrace.lo
 	$(BUILDGOX)
 internal/race.gox: internal/race.lo
 	$(BUILDGOX)
@@ -4107,6 +4304,8 @@ net/http/fcgi.gox: net/http/fcgi.lo
 	$(BUILDGOX)
 net/http/httptest.gox: net/http/httptest.lo
 	$(BUILDGOX)
+net/http/httptrace.gox: net/http/httptrace.lo
+	$(BUILDGOX)
 net/http/httputil.gox: net/http/httputil.lo
 	$(BUILDGOX)
 net/http/pprof.gox: net/http/pprof.lo
@@ -4169,6 +4368,7 @@ unicode/utf8.gox: unicode/utf8.lo
 TEST_PACKAGES = \
 	bufio/check \
 	bytes/check \
+	context/check \
 	errors/check \
 	expvar/check \
 	flag/check \
@@ -4252,6 +4452,9 @@ TEST_PACKAGES = \
 	go/scanner/check \
 	go/token/check \
 	go/types/check \
+	golang_org/x/net/http2/hpack/check \
+	golang_org/x/net/lex/httplex/check \
+	$(golang_org_x_net_route_check) \
 	hash/adler32/check \
 	hash/crc32/check \
 	hash/crc64/check \
@@ -4261,7 +4464,6 @@ TEST_PACKAGES = \
 	image/jpeg/check \
 	image/png/check \
 	index/suffixarray/check \
-	internal/golang.org/x/net/http2/hpack/check \
 	internal/singleflight/check \
 	internal/trace/check \
 	io/ioutil/check \
@@ -4276,6 +4478,7 @@ TEST_PACKAGES = \
 	net/http/cookiejar/check \
 	net/http/fcgi/check \
 	net/http/httptest/check \
+	net/http/httptrace/check \
 	net/http/httputil/check \
 	net/http/internal/check \
 	net/internal/socktest/check \
diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 216ab6a9b1f..740885ef372 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -174,14 +174,14 @@ am_libnetgo_a_OBJECTS = $(am__objects_3)
 libnetgo_a_OBJECTS = $(am_libnetgo_a_OBJECTS)
 LTLIBRARIES = $(toolexeclib_LTLIBRARIES)
 am__DEPENDENCIES_1 =
-am__DEPENDENCIES_2 = bufio.lo bytes.lo bytes/index.lo crypto.lo \
-	encoding.lo errors.lo expvar.lo flag.lo fmt.lo hash.lo html.lo \
-	image.lo io.lo log.lo math.lo mime.lo net.lo os.lo path.lo \
-	reflect-go.lo reflect/makefunc_ffi_c.lo regexp.lo \
-	runtime-go.lo sort.lo strconv.lo strings.lo strings/index.lo \
-	sync.lo syscall.lo syscall/errno.lo syscall/signame.lo \
-	syscall/wait.lo testing.lo time-go.lo unicode.lo \
-	archive/tar.lo archive/zip.lo compress/bzip2.lo \
+am__DEPENDENCIES_2 = bufio.lo bytes.lo bytes/index.lo context.lo \
+	crypto.lo encoding.lo errors.lo expvar.lo flag.lo fmt.lo \
+	hash.lo html.lo image.lo io.lo log.lo math.lo mime.lo net.lo \
+	os.lo path.lo reflect-go.lo reflect/makefunc_ffi_c.lo \
+	regexp.lo runtime-go.lo sort.lo strconv.lo strings.lo \
+	strings/index.lo sync.lo syscall.lo syscall/errno.lo \
+	syscall/signame.lo syscall/wait.lo testing.lo time-go.lo \
+	unicode.lo archive/tar.lo archive/zip.lo compress/bzip2.lo \
 	compress/flate.lo compress/gzip.lo compress/lzw.lo \
 	compress/zlib.lo container/heap.lo container/list.lo \
 	container/ring.lo crypto/aes.lo crypto/cipher.lo crypto/des.lo \
@@ -199,22 +199,24 @@ am__DEPENDENCIES_2 = bufio.lo bytes.lo bytes/index.lo crypto.lo \
 	go/ast.lo go/build.lo go/constant.lo go/doc.lo go/format.lo \
 	go/importer.lo go/internal/gcimporter.lo \
 	go/internal/gccgoimporter.lo go/parser.lo go/printer.lo \
-	go/scanner.lo go/token.lo go/types.lo hash/adler32.lo \
-	hash/crc32.lo hash/crc64.lo hash/fnv.lo net/http/cgi.lo \
-	net/http/cookiejar.lo net/http/fcgi.lo net/http/httptest.lo \
+	go/scanner.lo go/token.lo go/types.lo \
+	golang_org/x/net/http2/hpack.lo \
+	golang_org/x/net/lex/httplex.lo $(golang_org_x_net_route_lo) \
+	hash/adler32.lo hash/crc32.lo hash/crc64.lo hash/fnv.lo \
+	net/http/cgi.lo net/http/cookiejar.lo net/http/fcgi.lo \
+	net/http/httptest.lo net/http/httptrace.lo \
 	net/http/httputil.lo net/http/internal.lo net/http/pprof.lo \
 	image/color.lo image/color/palette.lo image/draw.lo \
 	image/gif.lo image/internal/imageutil.lo image/jpeg.lo \
-	image/png.lo index/suffixarray.lo \
-	internal/golang.org/x/net/http2/hpack.lo internal/race.lo \
-	internal/singleflight.lo internal/syscall/unix.lo \
-	internal/testenv.lo internal/trace.lo io/ioutil.lo \
-	log/syslog.lo log/syslog/syslog_c.lo math/big.lo math/cmplx.lo \
-	math/rand.lo mime/multipart.lo mime/quotedprintable.lo \
-	net/http.lo net/internal/socktest.lo net/mail.lo net/rpc.lo \
-	net/smtp.lo net/textproto.lo net/url.lo old/regexp.lo \
-	old/template.lo os/exec.lo $(am__DEPENDENCIES_1) os/signal.lo \
-	os/user.lo path/filepath.lo regexp/syntax.lo \
+	image/png.lo index/suffixarray.lo internal/nettrace.lo \
+	internal/race.lo internal/singleflight.lo \
+	internal/syscall/unix.lo internal/testenv.lo internal/trace.lo \
+	io/ioutil.lo log/syslog.lo log/syslog/syslog_c.lo math/big.lo \
+	math/cmplx.lo math/rand.lo mime/multipart.lo \
+	mime/quotedprintable.lo net/http.lo net/internal/socktest.lo \
+	net/mail.lo net/rpc.lo net/smtp.lo net/textproto.lo net/url.lo \
+	old/regexp.lo old/template.lo os/exec.lo $(am__DEPENDENCIES_1) \
+	os/signal.lo os/user.lo path/filepath.lo regexp/syntax.lo \
 	net/rpc/jsonrpc.lo runtime/debug.lo runtime/pprof.lo \
 	sync/atomic.lo sync/atomic_c.lo text/scanner.lo \
 	text/tabwriter.lo text/template.lo text/template/parse.lo \
@@ -576,6 +578,7 @@ FLAGS_TO_PASS = $(AM_MAKEFLAGS)
 toolexeclibgo_DATA = \
 	bufio.gox \
 	bytes.gox \
+	context.gox \
 	crypto.gox \
 	encoding.gox \
 	errors.gox \
@@ -758,6 +761,7 @@ toolexeclibgonethttp_DATA = \
 	net/http/cookiejar.gox \
 	net/http/fcgi.gox \
 	net/http/httptest.gox \
+	net/http/httptrace.gox \
 	net/http/httputil.gox \
 	net/http/pprof.gox
 
@@ -946,6 +950,9 @@ go_bytes_files = \
 go_bytes_c_files = \
 	go/bytes/indexbyte.c
 
+go_context_files = \
+	go/context/context.go
+
 go_crypto_files = \
 	go/crypto/crypto.go
 
@@ -1086,9 +1093,10 @@ go_mime_files = \
 @LIBGO_IS_DRAGONFLY_TRUE@@LIBGO_IS_FREEBSD_FALSE@@LIBGO_IS_LINUX_FALSE@go_net_sendfile_file = go/net/sendfile_dragonfly.go
 @LIBGO_IS_FREEBSD_TRUE@@LIBGO_IS_LINUX_FALSE@go_net_sendfile_file = go/net/sendfile_freebsd.go
 @LIBGO_IS_LINUX_TRUE@go_net_sendfile_file = go/net/sendfile_linux.go
-@LIBGO_IS_DRAGONFLY_FALSE@@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_FALSE@go_net_interface_file = go/net/interface_stub.go
-@LIBGO_IS_DRAGONFLY_TRUE@@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_FALSE@go_net_interface_file = go/net/interface_dragonfly.go
-@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_TRUE@go_net_interface_file = go/net/interface_netbsd.go
+@LIBGO_IS_DRAGONFLY_FALSE@@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_FALSE@@LIBGO_IS_OPENBSD_FALSE@go_net_interface_file = go/net/interface_stub.go
+@LIBGO_IS_DRAGONFLY_FALSE@@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_FALSE@@LIBGO_IS_OPENBSD_TRUE@go_net_interface_file = go/net/interface_bsdvar.go
+@LIBGO_IS_DRAGONFLY_TRUE@@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_FALSE@go_net_interface_file = go/net/interface_bsdvar.go
+@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_NETBSD_TRUE@go_net_interface_file = go/net/interface_bsdvar.go
 @LIBGO_IS_LINUX_TRUE@go_net_interface_file = go/net/interface_linux.go
 @LIBGO_IS_FREEBSD_FALSE@@LIBGO_IS_LINUX_FALSE@go_net_cloexec_file = go/net/sys_cloexec.go
 @LIBGO_IS_FREEBSD_TRUE@@LIBGO_IS_LINUX_FALSE@go_net_cloexec_file = go/net/sock_cloexec.go go/net/hook_cloexec.go
@@ -1129,6 +1137,7 @@ go_net_common_files = \
 	go/net/nss.go \
 	go/net/parse.go \
 	go/net/pipe.go \
+	go/net/port.go \
 	go/net/fd_poll_runtime.go \
 	go/net/port_unix.go \
 	$(go_net_sendfile_file) \
@@ -1190,6 +1199,10 @@ go_netgo_files = \
 @LIBGO_IS_DARWIN_FALSE@@LIBGO_IS_DRAGONFLY_FALSE@@LIBGO_IS_FREEBSD_TRUE@go_os_sticky_file = go/os/sticky_bsd.go
 @LIBGO_IS_DARWIN_FALSE@@LIBGO_IS_DRAGONFLY_TRUE@go_os_sticky_file = go/os/sticky_bsd.go
 @LIBGO_IS_DARWIN_TRUE@go_os_sticky_file = go/os/sticky_bsd.go
+@LIBGO_IS_DARWIN_FALSE@@LIBGO_IS_FREEBSD_FALSE@@LIBGO_IS_LINUX_FALSE@go_os_wait_file = go/os/wait_unimp.go
+@LIBGO_IS_DARWIN_FALSE@@LIBGO_IS_FREEBSD_TRUE@@LIBGO_IS_LINUX_FALSE@go_os_wait_file = go/os/wait_wait6.go
+@LIBGO_IS_DARWIN_TRUE@@LIBGO_IS_LINUX_FALSE@go_os_wait_file = go/os/wait_waitid.go
+@LIBGO_IS_LINUX_TRUE@go_os_wait_file = go/os/wait_waitid.go
 go_os_files = \
 	$(go_os_dir_file) \
 	go/os/dir.go \
@@ -1215,7 +1228,8 @@ go_os_files = \
 	$(go_os_sys_file) \
 	$(go_os_cloexec_file) \
 	go/os/types.go \
-	go/os/types_unix.go
+	go/os/types_unix.go \
+	$(go_os_wait_file)
 
 go_path_files = \
 	go/path/match.go \
@@ -1248,6 +1262,7 @@ go_runtime_files = \
 	go/runtime/error.go \
 	go/runtime/extern.go \
 	go/runtime/mem.go \
+	go/runtime/symtab.go \
 	version.go
 
 noinst_DATA = zstdpkglist.go
@@ -1304,6 +1319,7 @@ go_testing_files = \
 	go/testing/benchmark.go \
 	go/testing/cover.go \
 	go/testing/example.go \
+	go/testing/match.go \
 	go/testing/testing.go
 
 go_time_files = \
@@ -1331,6 +1347,7 @@ go_unicode_files = \
 @LIBGO_IS_SOLARIS_TRUE@archive_tar_atim_file = go/archive/tar/stat_atim.go
 go_archive_tar_files = \
 	go/archive/tar/common.go \
+	go/archive/tar/format.go \
 	go/archive/tar/reader.go \
 	go/archive/tar/stat_unix.go \
 	go/archive/tar/writer.go \
@@ -1349,8 +1366,9 @@ go_compress_bzip2_files = \
 	go/compress/bzip2/move_to_front.go
 
 go_compress_flate_files = \
-	go/compress/flate/copy.go \
 	go/compress/flate/deflate.go \
+	go/compress/flate/deflatefast.go \
+	go/compress/flate/dict_decoder.go \
 	go/compress/flate/huffman_bit_writer.go \
 	go/compress/flate/huffman_code.go \
 	go/compress/flate/inflate.go \
@@ -1382,7 +1400,8 @@ go_crypto_aes_files = \
 	go/crypto/aes/block.go \
 	go/crypto/aes/cipher.go \
 	go/crypto/aes/cipher_generic.go \
-	go/crypto/aes/const.go
+	go/crypto/aes/const.go \
+	go/crypto/aes/modes.go
 
 go_crypto_cipher_files = \
 	go/crypto/cipher/cbc.go \
@@ -1418,7 +1437,8 @@ go_crypto_md5_files = \
 	go/crypto/md5/md5block.go \
 	go/crypto/md5/md5block_generic.go
 
-@LIBGO_IS_LINUX_FALSE@crypto_rand_file = 
+@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_OPENBSD_FALSE@crypto_rand_file = 
+@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_OPENBSD_TRUE@crypto_rand_file = go/crypto/rand/rand_openbsd.go
 @LIBGO_IS_LINUX_TRUE@crypto_rand_file = go/crypto/rand/rand_linux.go
 go_crypto_rand_files = \
 	go/crypto/rand/eagain.go \
@@ -1443,11 +1463,13 @@ go_crypto_sha1_files = \
 
 go_crypto_sha256_files = \
 	go/crypto/sha256/sha256.go \
-	go/crypto/sha256/sha256block.go
+	go/crypto/sha256/sha256block.go \
+	go/crypto/sha256/sha256block_generic.go
 
 go_crypto_sha512_files = \
 	go/crypto/sha512/sha512.go \
-	go/crypto/sha512/sha512block.go
+	go/crypto/sha512/sha512block.go \
+	go/crypto/sha512/sha512block_generic.go
 
 go_crypto_subtle_files = \
 	go/crypto/subtle/constant_time.go
@@ -1523,7 +1545,10 @@ go_debug_macho_files = \
 
 go_debug_pe_files = \
 	go/debug/pe/file.go \
-	go/debug/pe/pe.go
+	go/debug/pe/pe.go \
+	go/debug/pe/section.go \
+	go/debug/pe/string.go \
+	go/debug/pe/symbol.go
 
 go_debug_plan9obj_files = \
 	go/debug/plan9obj/file.go \
@@ -1688,6 +1713,39 @@ go_go_internal_gccgoimporter_files = \
 	go/go/internal/gccgoimporter/importer.go \
 	go/go/internal/gccgoimporter/parser.go
 
+go_golang_org_x_net_http2_hpack_files = \
+	go/golang_org/x/net/http2/hpack/encode.go \
+	go/golang_org/x/net/http2/hpack/hpack.go \
+	go/golang_org/x/net/http2/hpack/huffman.go \
+	go/golang_org/x/net/http2/hpack/tables.go
+
+go_golang_org_x_net_lex_httplex_files = \
+	go/golang_org/x/net/lex/httplex/httplex.go
+
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DARWIN_TRUE@x_net_route_files = 
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@x_net_route_files = 
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@x_net_route_files = 
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_NETBSD_TRUE@x_net_route_files = 
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_OPENBSD_TRUE@x_net_route_files = 
+@LIBGO_IS_386_TRUE@@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@x_net_route_freebsd_file = 
+@LIBGO_IS_ARM_TRUE@@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@x_net_route_freebsd_file = 
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@@LIBGO_IS_X86_64_TRUE@x_net_route_freebsd_file = 
+@LIBGO_IS_BSD_TRUE@go_golang_org_x_net_route_files = \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/address.go \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/binary.go \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/interface.go \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/message.go \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/route.go \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/syscall.go \
+@LIBGO_IS_BSD_TRUE@	go/golang_org/x/net/route/sys.go \
+@LIBGO_IS_BSD_TRUE@	$(x_net_route_files)
+
+@LIBGO_IS_BSD_TRUE@golang_org_x_net_route_lo = \
+@LIBGO_IS_BSD_TRUE@	golang_org/x/net/route/route.lo
+
+@LIBGO_IS_BSD_TRUE@golang_org_x_net_route_check = \
+@LIBGO_IS_BSD_TRUE@	golang_org/x/net/route/check
+
 go_hash_adler32_files = \
 	go/hash/adler32/adler32.go
 
@@ -1750,11 +1808,8 @@ go_index_suffixarray_files = \
 	go/index/suffixarray/qsufsort.go \
 	go/index/suffixarray/suffixarray.go
 
-go_internal_golang_org_x_net_http2_hpack_files = \
-	go/internal/golang.org/x/net/http2/hpack/encode.go \
-	go/internal/golang.org/x/net/http2/hpack/hpack.go \
-	go/internal/golang.org/x/net/http2/hpack/huffman.go \
-	go/internal/golang.org/x/net/http2/hpack/tables.go
+go_internal_nettrace_files = \
+	go/internal/nettrace/nettrace.go
 
 go_internal_race_files = \
 	go/internal/race/doc.go \
@@ -1763,13 +1818,15 @@ go_internal_race_files = \
 go_internal_singleflight_files = \
 	go/internal/singleflight/singleflight.go
 
-@LIBGO_IS_386_FALSE@@LIBGO_IS_ARM_FALSE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_MIPS64_FALSE@@LIBGO_IS_PPC64_FALSE@@LIBGO_IS_X86_64_FALSE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_generic.go
+@LIBGO_IS_386_FALSE@@LIBGO_IS_ARM_FALSE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_MIPS64_FALSE@@LIBGO_IS_PPC64_FALSE@@LIBGO_IS_S390X_FALSE@@LIBGO_IS_X86_64_FALSE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_generic.go
+@LIBGO_IS_386_FALSE@@LIBGO_IS_ARM_FALSE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_MIPS64_FALSE@@LIBGO_IS_PPC64_FALSE@@LIBGO_IS_S390X_TRUE@@LIBGO_IS_X86_64_FALSE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_s390x.go
 @LIBGO_IS_386_FALSE@@LIBGO_IS_ARM_FALSE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_MIPS64_TRUE@@LIBGO_IS_PPC64_FALSE@@LIBGO_IS_X86_64_FALSE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_mips64x.go
 @LIBGO_IS_386_FALSE@@LIBGO_IS_ARM_FALSE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_PPC64_TRUE@@LIBGO_IS_X86_64_FALSE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_ppc64x.go
 @LIBGO_IS_386_FALSE@@LIBGO_IS_ARM_TRUE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_X86_64_FALSE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_arm.go
 @LIBGO_IS_386_FALSE@@LIBGO_IS_LINUX_TRUE@@LIBGO_IS_X86_64_TRUE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_amd64.go
 @LIBGO_IS_386_TRUE@@LIBGO_IS_LINUX_TRUE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getrandom_linux.go go/internal/syscall/unix/getrandom_linux_386.go
-@LIBGO_IS_LINUX_FALSE@internal_syscall_unix_getrandom_files = 
+@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_OPENBSD_FALSE@internal_syscall_unix_getrandom_files = 
+@LIBGO_IS_LINUX_FALSE@@LIBGO_IS_OPENBSD_TRUE@internal_syscall_unix_getrandom_files = go/internal/syscall/unix/getentropy_openbsd.go
 go_internal_syscall_unix_files = \
 	go/internal/syscall/unix/dummy.go \
 	$(internal_syscall_unix_getrandom_files)
@@ -1779,6 +1836,7 @@ go_internal_testenv_files = \
 
 go_internal_trace_files = \
 	go/internal/trace/goroutines.go \
+	go/internal/trace/order.go \
 	go/internal/trace/parser.go
 
 go_io_ioutil_files = \
@@ -1844,8 +1902,8 @@ go_net_http_files = \
 	go/net/http/fs.go \
 	go/net/http/h2_bundle.go \
 	go/net/http/header.go \
+	go/net/http/http.go \
 	go/net/http/jar.go \
-	go/net/http/lex.go \
 	go/net/http/method.go \
 	go/net/http/request.go \
 	go/net/http/response.go \
@@ -1885,12 +1943,16 @@ go_net_http_fcgi_files = \
 	go/net/http/fcgi/fcgi.go
 
 go_net_http_httptest_files = \
+	go/net/http/httptest/httptest.go \
 	go/net/http/httptest/recorder.go \
 	go/net/http/httptest/server.go
 
 go_net_http_pprof_files = \
 	go/net/http/pprof/pprof.go
 
+go_net_http_httptrace_files = \
+	go/net/http/httptrace/trace.go
+
 go_net_http_httputil_files = \
 	go/net/http/httputil/dump.go \
 	go/net/http/httputil/httputil.go \
@@ -1932,11 +1994,14 @@ go_os_signal_files = \
 
 @LIBGO_IS_SOLARIS_FALSE@os_user_decls_file = go/os/user/decls_unix.go
 @LIBGO_IS_SOLARIS_TRUE@os_user_decls_file = go/os/user/decls_solaris.go
+@LIBGO_IS_SOLARIS_FALSE@os_user_listgroups_file = go/os/user/listgroups_unix.go
+@LIBGO_IS_SOLARIS_TRUE@os_user_listgroups_file = go/os/user/listgroups_solaris.go
 go_os_user_files = \
 	go/os/user/lookup.go \
 	go/os/user/lookup_unix.go \
 	go/os/user/user.go \
-	$(os_user_decls_file)
+	$(os_user_decls_file) \
+	$(os_user_listgroups_file)
 
 go_path_filepath_files = \
 	go/path/filepath/match.go \
@@ -2158,6 +2223,7 @@ libgo_go_objs = \
 	bufio.lo \
 	bytes.lo \
 	bytes/index.lo \
+	context.lo \
 	crypto.lo \
 	encoding.lo \
 	errors.lo \
@@ -2253,6 +2319,9 @@ libgo_go_objs = \
 	go/scanner.lo \
 	go/token.lo \
 	go/types.lo \
+	golang_org/x/net/http2/hpack.lo \
+	golang_org/x/net/lex/httplex.lo \
+	$(golang_org_x_net_route_lo) \
 	hash/adler32.lo \
 	hash/crc32.lo \
 	hash/crc64.lo \
@@ -2261,6 +2330,7 @@ libgo_go_objs = \
 	net/http/cookiejar.lo \
 	net/http/fcgi.lo \
 	net/http/httptest.lo \
+	net/http/httptrace.lo \
 	net/http/httputil.lo \
 	net/http/internal.lo \
 	net/http/pprof.lo \
@@ -2272,7 +2342,7 @@ libgo_go_objs = \
 	image/jpeg.lo \
 	image/png.lo \
 	index/suffixarray.lo \
-	internal/golang.org/x/net/http2/hpack.lo \
+	internal/nettrace.lo \
 	internal/race.lo \
 	internal/singleflight.lo \
 	internal/syscall/unix.lo \
@@ -2439,6 +2509,7 @@ BUILDGOX = \
 TEST_PACKAGES = \
 	bufio/check \
 	bytes/check \
+	context/check \
 	errors/check \
 	expvar/check \
 	flag/check \
@@ -2522,6 +2593,9 @@ TEST_PACKAGES = \
 	go/scanner/check \
 	go/token/check \
 	go/types/check \
+	golang_org/x/net/http2/hpack/check \
+	golang_org/x/net/lex/httplex/check \
+	$(golang_org_x_net_route_check) \
 	hash/adler32/check \
 	hash/crc32/check \
 	hash/crc64/check \
@@ -2531,7 +2605,6 @@ TEST_PACKAGES = \
 	image/jpeg/check \
 	image/png/check \
 	index/suffixarray/check \
-	internal/golang.org/x/net/http2/hpack/check \
 	internal/singleflight/check \
 	internal/trace/check \
 	io/ioutil/check \
@@ -2546,6 +2619,7 @@ TEST_PACKAGES = \
 	net/http/cookiejar/check \
 	net/http/fcgi/check \
 	net/http/httptest/check \
+	net/http/httptrace/check \
 	net/http/httputil/check \
 	net/http/internal/check \
 	net/internal/socktest/check \
@@ -4761,6 +4835,34 @@ s-zstdpkglist: Makefile
 	echo '}' >> zstdpkglist.go.tmp
 	$(SHELL) $(srcdir)/mvifdiff.sh zstdpkglist.go.tmp zstdpkglist.go
 	$(STAMP) $@
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DARWIN_TRUE@	go/golang_org/x/net/route/interface_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DARWIN_TRUE@	go/golang_org/x/net/route/interface_multicast.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DARWIN_TRUE@	go/golang_org/x/net/route/route_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DARWIN_TRUE@	go/golang_org/x/net/route/sys_darwin.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DARWIN_TRUE@	go/golang_org/x/net/route/zsys_darwin.go
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@	go/golang_org/x/net/route/interface_announce.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@	go/golang_org/x/net/route/interface_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@	go/golang_org/x/net/route/interface_multicast.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@	go/golang_org/x/net/route/route_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@	go/golang_org/x/net/route/sys_dragonfly.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_DRAGONFLY_TRUE@	go/golang_org/x/net/route/zsys_dragonfly.go
+@LIBGO_IS_386_TRUE@@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/zsys_freebsd_386.go
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@@LIBGO_IS_X86_64_TRUE@	go/golang_org/x/net/route/zsys_freebsd_amd64.go
+@LIBGO_IS_ARM_TRUE@@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/zsys_freebsd_arm.go
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/interface_announce.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/interface_freebsd.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/interface_multicast.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/route_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	go/golang_org/x/net/route/sys_freebsd.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_FREEBSD_TRUE@	$(x_net_route_freebsd_file)
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_NETBSD_TRUE@	go/golang_org/x/net/route/interface_announce.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_NETBSD_TRUE@	go/golang_org/x/net/route/interface_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_NETBSD_TRUE@	go/golang_org/x/net/route/route_classic.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_NETBSD_TRUE@	go/golang_org/x/net/route/sys_netbsd.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_NETBSD_TRUE@	go/golang_org/x/net/route/zsys_netbsd.go
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_OPENBSD_TRUE@	go/golang_org/x/net/route/route_openbsd.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_OPENBSD_TRUE@	go/golang_org/x/net/route/sys_openbsd.go \
+@LIBGO_IS_BSD_TRUE@@LIBGO_IS_OPENBSD_TRUE@	go/golang_org/x/net/route/zsys_openbsd.go
 
 libcalls.go: s-libcalls; @true
 s-libcalls: libcalls-list go/syscall/mksyscall.awk $(go_base_syscall_files)
@@ -4841,6 +4943,15 @@ bytes/check: $(CHECK_DEPS)
 	@$(CHECK)
 .PHONY: bytes/check
 
+@go_include@ context.lo.dep
+context.lo.dep: $(go_context_files)
+	$(BUILDDEPS)
+context.lo: $(go_context_files)
+	$(BUILDPACKAGE)
+context/check: $(CHECK_DEPS)
+	@$(CHECK)
+.PHONY: context/check
+
 @go_include@ crypto.lo.dep
 crypto.lo.dep: $(go_crypto_files)
 	$(BUILDDEPS)
@@ -5656,6 +5767,33 @@ go/internal/gccgoimporter/check: $(CHECK_DEPS)
 	@$(CHECK)
 .PHONY: go/internal/gccgoimporter/check
 
+@go_include@ golang_org/x/net/http2/hpack.lo.dep
+golang_org/x/net/http2/hpack.lo.dep: $(go_golang_org_x_net_http2_hpack_files)
+	$(BUILDDEPS)
+golang_org/x/net/http2/hpack.lo: $(go_golang_org_x_net_http2_hpack_files)
+	$(BUILDPACKAGE)
+golang_org/x/net/http2/hpack/check: $(CHECK_DEPS)
+	@$(CHECK)
+.PHONY: golang_org/x/net/http2/hpack/check
+
+@go_include@ golang_org/x/net/lex/httplex.lo.dep
+golang_org/x/net/lex/httplex.lo.dep: $(go_golang_org_x_net_lex_httplex_files)
+	$(BUILDDEPS)
+golang_org/x/net/lex/httplex.lo: $(go_golang_org_x_net_lex_httplex_files)
+	$(BUILDPACKAGE)
+golang_org/x/net/lex/httplex/check: $(CHECK_DEPS)
+	@$(CHECK)
+.PHONY: golang_org/x/net/lex/httplex/check
+
+@LIBGO_IS_BSD_TRUE@@go_include@ golang_org/x/net/route.lo.dep
+@LIBGO_IS_BSD_TRUE@golang_org/x/net/route.lo.dep: $(go_golang_org_x_net_route_files)
+@LIBGO_IS_BSD_TRUE@	$(BUILDDEPS)
+@LIBGO_IS_BSD_TRUE@golang_org/x/net/route.lo: $(go_golang_org_x_net_route_files)
+@LIBGO_IS_BSD_TRUE@	$(BUILDPACKAGE)
+@LIBGO_IS_BSD_TRUE@golang_org/x/net/route/check: $(CHECK_DEPS)
+@LIBGO_IS_BSD_TRUE@	@$(CHECK)
+.PHONY: golang_org/x/net/route/check
+
 @go_include@ hash/adler32.lo.dep
 hash/adler32.lo.dep: $(go_hash_adler32_files)
 	$(BUILDDEPS)
@@ -5764,14 +5902,14 @@ index/suffixarray/check: $(CHECK_DEPS)
 	@$(CHECK)
 .PHONY: index/suffixarray/check
 
-@go_include@ internal/golang.org/x/net/http2/hpack.lo.dep
-internal/golang.org/x/net/http2/hpack.lo.dep: $(go_internal_golang_org_x_net_http2_hpack_files)
+@go_include@ internal/nettrace.lo.dep
+internal/nettrace.lo.dep: $(go_internal_nettrace_files)
 	$(BUILDDEPS)
-internal/golang.org/x/net/http2/hpack.lo: $(go_internal_golang_org_x_net_http2_hpack_files)
+internal/nettrace.lo: $(go_internal_nettrace_files)
 	$(BUILDPACKAGE)
-internal/golang.org/x/net/http2/hpack/check: $(CHECK_DEPS)
+internal/nettrace/check: $(CHECK_DEPS)
 	@$(CHECK)
-.PHONY: internal/golang.org/x/net/http2/hpack/check
+.PHONY: internal/nettrace/check
 
 @go_include@ internal/race.lo.dep
 internal/race.lo.dep: $(go_internal_race_files)
@@ -5974,6 +6112,15 @@ net/http/httptest/check: $(check_deps)
 	@$(CHECK)
 .PHONY: net/http/httptest/check
 
+@go_include@ net/http/httptrace.lo.dep
+net/http/httptrace.lo.dep: $(go_net_http_httptrace_files)
+	$(BUILDDEPS)
+net/http/httptrace.lo: $(go_net_http_httptrace_files)
+	$(BUILDPACKAGE)
+net/http/httptrace/check: $(check_deps)
+	@$(CHECK)
+.PHONY: net/http/httptrace/check
+
 @go_include@ net/http/httputil.lo.dep
 net/http/httputil.lo.dep: $(go_net_http_httputil_files)
 	$(BUILDDEPS)
@@ -6205,6 +6352,8 @@ bufio.gox: bufio.lo
 	$(BUILDGOX)
 bytes.gox: bytes.lo
 	$(BUILDGOX)
+context.gox: context.lo
+	$(BUILDGOX)
 crypto.gox: crypto.lo
 	$(BUILDGOX)
 encoding.gox: encoding.lo
@@ -6399,6 +6548,15 @@ go/internal/gcimporter.gox: go/internal/gcimporter.lo
 go/internal/gccgoimporter.gox: go/internal/gccgoimporter.lo
 	$(BUILDGOX)
 
+golang_org/x/net/http2/hpack.gox: golang_org/x/net/http2/hpack.lo
+	$(BUILDGOX)
+
+golang_org/x/net/lex/httplex.gox: golang_org/x/net/lex/httplex.lo
+	$(BUILDGOX)
+
+@LIBGO_IS_BSD_TRUE@golang_org/x/net/route.gox: golang_org/x/net/route.lo
+@LIBGO_IS_BSD_TRUE@	$(BUILDGOX)
+
 hash/adler32.gox: hash/adler32.lo
 	$(BUILDGOX)
 hash/crc32.gox: hash/crc32.lo
@@ -6427,7 +6585,7 @@ image/color/palette.gox: image/color/palette.lo
 index/suffixarray.gox: index/suffixarray.lo
 	$(BUILDGOX)
 
-internal/golang.org/x/net/http2/hpack.gox: internal/golang.org/x/net/http2/hpack.lo
+internal/nettrace.gox: internal/nettrace.lo
 	$(BUILDGOX)
 internal/race.gox: internal/race.lo
 	$(BUILDGOX)
@@ -6479,6 +6637,8 @@ net/http/fcgi.gox: net/http/fcgi.lo
 	$(BUILDGOX)
 net/http/httptest.gox: net/http/httptest.lo
 	$(BUILDGOX)
+net/http/httptrace.gox: net/http/httptrace.lo
+	$(BUILDGOX)
 net/http/httputil.gox: net/http/httputil.lo
 	$(BUILDGOX)
 net/http/pprof.gox: net/http/pprof.lo
diff --git a/libgo/VERSION b/libgo/VERSION
index e1bf218d1df..a323ae8190f 100644
--- a/libgo/VERSION
+++ b/libgo/VERSION
@@ -1 +1 @@
-go1.6.1
\ No newline at end of file
+go1.7rc3
diff --git a/libgo/configure b/libgo/configure
index a418a885310..ee86b35d8a6 100755
--- a/libgo/configure
+++ b/libgo/configure
@@ -670,6 +670,8 @@ LIBGO_IS_386_FALSE
 LIBGO_IS_386_TRUE
 USE_DEJAGNU
 GOOS
+LIBGO_IS_BSD_FALSE
+LIBGO_IS_BSD_TRUE
 LIBGO_IS_SOLARIS_FALSE
 LIBGO_IS_SOLARIS_TRUE
 LIBGO_IS_RTEMS_FALSE
@@ -11126,7 +11128,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11129 "configure"
+#line 11131 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11232,7 +11234,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11235 "configure"
+#line 11237 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -13611,6 +13613,14 @@ else
   LIBGO_IS_SOLARIS_FALSE=
 fi
 
+ if test $is_darwin = yes -o $is_dragonfly = yes -o $is_freebsd = yes -o $is_netbsd = yes -o $is_openbsd = yes; then
+  LIBGO_IS_BSD_TRUE=
+  LIBGO_IS_BSD_FALSE='#'
+else
+  LIBGO_IS_BSD_TRUE='#'
+  LIBGO_IS_BSD_FALSE=
+fi
+
 
 
 USE_DEJAGNU=no
@@ -15769,6 +15779,10 @@ if test -z "${LIBGO_IS_SOLARIS_TRUE}" && test -z "${LIBGO_IS_SOLARIS_FALSE}"; th
   as_fn_error "conditional \"LIBGO_IS_SOLARIS\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${LIBGO_IS_BSD_TRUE}" && test -z "${LIBGO_IS_BSD_FALSE}"; then
+  as_fn_error "conditional \"LIBGO_IS_BSD\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${LIBGO_IS_386_TRUE}" && test -z "${LIBGO_IS_386_FALSE}"; then
   as_fn_error "conditional \"LIBGO_IS_386\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
diff --git a/libgo/configure.ac b/libgo/configure.ac
index a86bcb82311..cda34db037d 100644
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -172,6 +172,7 @@ AM_CONDITIONAL(LIBGO_IS_OPENBSD, test $is_openbsd = yes)
 AM_CONDITIONAL(LIBGO_IS_DRAGONFLY, test $is_dragonfly = yes)
 AM_CONDITIONAL(LIBGO_IS_RTEMS, test $is_rtems = yes)
 AM_CONDITIONAL(LIBGO_IS_SOLARIS, test $is_solaris = yes)
+AM_CONDITIONAL(LIBGO_IS_BSD, test $is_darwin = yes -o $is_dragonfly = yes -o $is_freebsd = yes -o $is_netbsd = yes -o $is_openbsd = yes)
 AC_SUBST(GOOS)
 
 dnl Test whether we need to use DejaGNU or whether we can use the
diff --git a/libgo/go/archive/tar/common.go b/libgo/go/archive/tar/common.go
index 36f4e239809..2a1e4321826 100644
--- a/libgo/go/archive/tar/common.go
+++ b/libgo/go/archive/tar/common.go
@@ -21,10 +21,8 @@ import (
 	"time"
 )
 
+// Header type flags.
 const (
-	blockSize = 512
-
-	// Types
 	TypeReg           = '0'    // regular file
 	TypeRegA          = '\x00' // regular file
 	TypeLink          = '1'    // hard link
@@ -61,12 +59,6 @@ type Header struct {
 	Xattrs     map[string]string
 }
 
-// File name constants from the tar spec.
-const (
-	fileNameSize       = 100 // Maximum number of bytes in a standard tar name.
-	fileNamePrefixSize = 155 // Maximum number of ustar extension bytes.
-)
-
 // FileInfo returns an os.FileInfo for the Header.
 func (h *Header) FileInfo() os.FileInfo {
 	return headerFileInfo{h}
@@ -279,33 +271,6 @@ func FileInfoHeader(fi os.FileInfo, link string) (*Header, error) {
 	return h, nil
 }
 
-var zeroBlock = make([]byte, blockSize)
-
-// POSIX specifies a sum of the unsigned byte values, but the Sun tar uses signed byte values.
-// We compute and return both.
-func checksum(header []byte) (unsigned int64, signed int64) {
-	for i := 0; i < len(header); i++ {
-		if i == 148 {
-			// The chksum field (header[148:156]) is special: it should be treated as space bytes.
-			unsigned += ' ' * 8
-			signed += ' ' * 8
-			i += 7
-			continue
-		}
-		unsigned += int64(header[i])
-		signed += int64(int8(header[i]))
-	}
-	return
-}
-
-type slicer []byte
-
-func (sp *slicer) next(n int) (b []byte) {
-	s := *sp
-	b, *sp = s[0:n], s[n:]
-	return
-}
-
 func isASCII(s string) bool {
 	for _, c := range s {
 		if c >= 0x80 {
diff --git a/libgo/go/archive/tar/format.go b/libgo/go/archive/tar/format.go
new file mode 100644
index 00000000000..c2c9910d002
--- /dev/null
+++ b/libgo/go/archive/tar/format.go
@@ -0,0 +1,197 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tar
+
+// Constants to identify various tar formats.
+const (
+	// The format is unknown.
+	formatUnknown = (1 << iota) / 2 // Sequence of 0, 1, 2, 4, 8, etc...
+
+	// The format of the original Unix V7 tar tool prior to standardization.
+	formatV7
+
+	// The old and new GNU formats, which are incompatible with USTAR.
+	// This does cover the old GNU sparse extension.
+	// This does not cover the GNU sparse extensions using PAX headers,
+	// versions 0.0, 0.1, and 1.0; these fall under the PAX format.
+	formatGNU
+
+	// Schily's tar format, which is incompatible with USTAR.
+	// This does not cover STAR extensions to the PAX format; these fall under
+	// the PAX format.
+	formatSTAR
+
+	// USTAR is the former standardization of tar defined in POSIX.1-1988.
+	// This is incompatible with the GNU and STAR formats.
+	formatUSTAR
+
+	// PAX is the latest standardization of tar defined in POSIX.1-2001.
+	// This is an extension of USTAR and is "backwards compatible" with it.
+	//
+	// Some newer formats add their own extensions to PAX, such as GNU sparse
+	// files and SCHILY extended attributes. Since they are backwards compatible
+	// with PAX, they will be labelled as "PAX".
+	formatPAX
+)
+
+// Magics used to identify various formats.
+const (
+	magicGNU, versionGNU     = "ustar ", " \x00"
+	magicUSTAR, versionUSTAR = "ustar\x00", "00"
+	trailerSTAR              = "tar\x00"
+)
+
+// Size constants from various tar specifications.
+const (
+	blockSize  = 512 // Size of each block in a tar stream
+	nameSize   = 100 // Max length of the name field in USTAR format
+	prefixSize = 155 // Max length of the prefix field in USTAR format
+)
+
+var zeroBlock block
+
+type block [blockSize]byte
+
+// Convert block to any number of formats.
+func (b *block) V7() *headerV7       { return (*headerV7)(b) }
+func (b *block) GNU() *headerGNU     { return (*headerGNU)(b) }
+func (b *block) STAR() *headerSTAR   { return (*headerSTAR)(b) }
+func (b *block) USTAR() *headerUSTAR { return (*headerUSTAR)(b) }
+func (b *block) Sparse() sparseArray { return (sparseArray)(b[:]) }
+
+// GetFormat checks that the block is a valid tar header based on the checksum.
+// It then attempts to guess the specific format based on magic values.
+// If the checksum fails, then formatUnknown is returned.
+func (b *block) GetFormat() (format int) {
+	// Verify checksum.
+	var p parser
+	value := p.parseOctal(b.V7().Chksum())
+	chksum1, chksum2 := b.ComputeChecksum()
+	if p.err != nil || (value != chksum1 && value != chksum2) {
+		return formatUnknown
+	}
+
+	// Guess the magic values.
+	magic := string(b.USTAR().Magic())
+	version := string(b.USTAR().Version())
+	trailer := string(b.STAR().Trailer())
+	switch {
+	case magic == magicUSTAR && trailer == trailerSTAR:
+		return formatSTAR
+	case magic == magicUSTAR:
+		return formatUSTAR
+	case magic == magicGNU && version == versionGNU:
+		return formatGNU
+	default:
+		return formatV7
+	}
+}
+
+// SetFormat writes the magic values necessary for specified format
+// and then updates the checksum accordingly.
+func (b *block) SetFormat(format int) {
+	// Set the magic values.
+	switch format {
+	case formatV7:
+		// Do nothing.
+	case formatGNU:
+		copy(b.GNU().Magic(), magicGNU)
+		copy(b.GNU().Version(), versionGNU)
+	case formatSTAR:
+		copy(b.STAR().Magic(), magicUSTAR)
+		copy(b.STAR().Version(), versionUSTAR)
+		copy(b.STAR().Trailer(), trailerSTAR)
+	case formatUSTAR, formatPAX:
+		copy(b.USTAR().Magic(), magicUSTAR)
+		copy(b.USTAR().Version(), versionUSTAR)
+	default:
+		panic("invalid format")
+	}
+
+	// Update checksum.
+	// This field is special in that it is terminated by a NULL then space.
+	var f formatter
+	field := b.V7().Chksum()
+	chksum, _ := b.ComputeChecksum() // Possible values are 256..128776
+	f.formatOctal(field[:7], chksum) // Never fails since 128776 < 262143
+	field[7] = ' '
+}
+
+// ComputeChecksum computes the checksum for the header block.
+// POSIX specifies a sum of the unsigned byte values, but the Sun tar used
+// signed byte values.
+// We compute and return both.
+func (b *block) ComputeChecksum() (unsigned, signed int64) {
+	for i, c := range b {
+		if 148 <= i && i < 156 {
+			c = ' ' // Treat the checksum field itself as all spaces.
+		}
+		unsigned += int64(uint8(c))
+		signed += int64(int8(c))
+	}
+	return unsigned, signed
+}
+
+type headerV7 [blockSize]byte
+
+func (h *headerV7) Name() []byte     { return h[000:][:100] }
+func (h *headerV7) Mode() []byte     { return h[100:][:8] }
+func (h *headerV7) UID() []byte      { return h[108:][:8] }
+func (h *headerV7) GID() []byte      { return h[116:][:8] }
+func (h *headerV7) Size() []byte     { return h[124:][:12] }
+func (h *headerV7) ModTime() []byte  { return h[136:][:12] }
+func (h *headerV7) Chksum() []byte   { return h[148:][:8] }
+func (h *headerV7) TypeFlag() []byte { return h[156:][:1] }
+func (h *headerV7) LinkName() []byte { return h[157:][:100] }
+
+type headerGNU [blockSize]byte
+
+func (h *headerGNU) V7() *headerV7       { return (*headerV7)(h) }
+func (h *headerGNU) Magic() []byte       { return h[257:][:6] }
+func (h *headerGNU) Version() []byte     { return h[263:][:2] }
+func (h *headerGNU) UserName() []byte    { return h[265:][:32] }
+func (h *headerGNU) GroupName() []byte   { return h[297:][:32] }
+func (h *headerGNU) DevMajor() []byte    { return h[329:][:8] }
+func (h *headerGNU) DevMinor() []byte    { return h[337:][:8] }
+func (h *headerGNU) AccessTime() []byte  { return h[345:][:12] }
+func (h *headerGNU) ChangeTime() []byte  { return h[357:][:12] }
+func (h *headerGNU) Sparse() sparseArray { return (sparseArray)(h[386:][:24*4+1]) }
+func (h *headerGNU) RealSize() []byte    { return h[483:][:12] }
+
+type headerSTAR [blockSize]byte
+
+func (h *headerSTAR) V7() *headerV7      { return (*headerV7)(h) }
+func (h *headerSTAR) Magic() []byte      { return h[257:][:6] }
+func (h *headerSTAR) Version() []byte    { return h[263:][:2] }
+func (h *headerSTAR) UserName() []byte   { return h[265:][:32] }
+func (h *headerSTAR) GroupName() []byte  { return h[297:][:32] }
+func (h *headerSTAR) DevMajor() []byte   { return h[329:][:8] }
+func (h *headerSTAR) DevMinor() []byte   { return h[337:][:8] }
+func (h *headerSTAR) Prefix() []byte     { return h[345:][:131] }
+func (h *headerSTAR) AccessTime() []byte { return h[476:][:12] }
+func (h *headerSTAR) ChangeTime() []byte { return h[488:][:12] }
+func (h *headerSTAR) Trailer() []byte    { return h[508:][:4] }
+
+type headerUSTAR [blockSize]byte
+
+func (h *headerUSTAR) V7() *headerV7     { return (*headerV7)(h) }
+func (h *headerUSTAR) Magic() []byte     { return h[257:][:6] }
+func (h *headerUSTAR) Version() []byte   { return h[263:][:2] }
+func (h *headerUSTAR) UserName() []byte  { return h[265:][:32] }
+func (h *headerUSTAR) GroupName() []byte { return h[297:][:32] }
+func (h *headerUSTAR) DevMajor() []byte  { return h[329:][:8] }
+func (h *headerUSTAR) DevMinor() []byte  { return h[337:][:8] }
+func (h *headerUSTAR) Prefix() []byte    { return h[345:][:155] }
+
+type sparseArray []byte
+
+func (s sparseArray) Entry(i int) sparseNode { return (sparseNode)(s[i*24:]) }
+func (s sparseArray) IsExtended() []byte     { return s[24*s.MaxEntries():][:1] }
+func (s sparseArray) MaxEntries() int        { return len(s) / 24 }
+
+type sparseNode []byte
+
+func (s sparseNode) Offset() []byte   { return s[00:][:12] }
+func (s sparseNode) NumBytes() []byte { return s[12:][:12] }
diff --git a/libgo/go/archive/tar/reader.go b/libgo/go/archive/tar/reader.go
index c8cb69a1784..096ef082bf8 100644
--- a/libgo/go/archive/tar/reader.go
+++ b/libgo/go/archive/tar/reader.go
@@ -13,7 +13,6 @@ import (
 	"io"
 	"io/ioutil"
 	"math"
-	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -30,11 +29,11 @@ const maxNanoSecondIntSize = 9
 // The Next method advances to the next file in the archive (including the first),
 // and then it can be treated as an io.Reader to access the file's data.
 type Reader struct {
-	r       io.Reader
-	err     error
-	pad     int64           // amount of padding (ignored) after current file entry
-	curr    numBytesReader  // reader for current file entry
-	hdrBuff [blockSize]byte // buffer to use in readHeader
+	r    io.Reader
+	err  error
+	pad  int64          // amount of padding (ignored) after current file entry
+	curr numBytesReader // reader for current file entry
+	blk  block          // buffer to use as temporary local storage
 }
 
 type parser struct {
@@ -99,17 +98,6 @@ const (
 	paxGNUSparseRealSize  = "GNU.sparse.realsize"
 )
 
-// Keywords for old GNU sparse headers
-const (
-	oldGNUSparseMainHeaderOffset               = 386
-	oldGNUSparseMainHeaderIsExtendedOffset     = 482
-	oldGNUSparseMainHeaderNumEntries           = 4
-	oldGNUSparseExtendedHeaderIsExtendedOffset = 504
-	oldGNUSparseExtendedHeaderNumEntries       = 21
-	oldGNUSparseOffsetSize                     = 12
-	oldGNUSparseNumBytesSize                   = 12
-)
-
 // NewReader creates a new Reader reading from r.
 func NewReader(r io.Reader) *Reader { return &Reader{r: r} }
 
@@ -307,7 +295,7 @@ func mergePAX(hdr *Header, headers map[string]string) error {
 			if err != nil {
 				return err
 			}
-			hdr.Size = int64(size)
+			hdr.Size = size
 		default:
 			if strings.HasPrefix(k, paxXattr) {
 				if hdr.Xattrs == nil {
@@ -337,17 +325,17 @@ func parsePAXTime(t string) (time.Time, error) {
 		if err != nil {
 			return time.Time{}, err
 		}
-		nano_buf := string(buf[pos+1:])
+		nanoBuf := string(buf[pos+1:])
 		// Pad as needed before converting to a decimal.
 		// For example .030 -> .030000000 -> 30000000 nanoseconds
-		if len(nano_buf) < maxNanoSecondIntSize {
+		if len(nanoBuf) < maxNanoSecondIntSize {
 			// Right pad
-			nano_buf += strings.Repeat("0", maxNanoSecondIntSize-len(nano_buf))
-		} else if len(nano_buf) > maxNanoSecondIntSize {
+			nanoBuf += strings.Repeat("0", maxNanoSecondIntSize-len(nanoBuf))
+		} else if len(nanoBuf) > maxNanoSecondIntSize {
 			// Right truncate
-			nano_buf = nano_buf[:maxNanoSecondIntSize]
+			nanoBuf = nanoBuf[:maxNanoSecondIntSize]
 		}
-		nanoseconds, err = strconv.ParseInt(string(nano_buf), 10, 0)
+		nanoseconds, err = strconv.ParseInt(nanoBuf, 10, 0)
 		if err != nil {
 			return time.Time{}, err
 		}
@@ -379,14 +367,14 @@ func parsePAX(r io.Reader) (map[string]string, error) {
 		}
 		sbuf = residual
 
-		keyStr := string(key)
+		keyStr := key
 		if keyStr == paxGNUSparseOffset || keyStr == paxGNUSparseNumBytes {
 			// GNU sparse format 0.0 special key. Write to sparseMap instead of using the headers map.
 			sparseMap.WriteString(value)
 			sparseMap.Write([]byte{','})
 		} else {
 			// Normal key. Set the value in the headers map.
-			headers[keyStr] = string(value)
+			headers[keyStr] = value
 		}
 	}
 	if sparseMap.Len() != 0 {
@@ -523,10 +511,10 @@ func (tr *Reader) skipUnread() error {
 		// io.Seeker, but calling Seek always returns an error and performs
 		// no action. Thus, we try an innocent seek to the current position
 		// to see if Seek is really supported.
-		pos1, err := sr.Seek(0, os.SEEK_CUR)
+		pos1, err := sr.Seek(0, io.SeekCurrent)
 		if err == nil {
 			// Seek seems supported, so perform the real Seek.
-			pos2, err := sr.Seek(dataSkip-1, os.SEEK_CUR)
+			pos2, err := sr.Seek(dataSkip-1, io.SeekCurrent)
 			if err != nil {
 				tr.err = err
 				return tr.err
@@ -543,17 +531,6 @@ func (tr *Reader) skipUnread() error {
 	return tr.err
 }
 
-func (tr *Reader) verifyChecksum(header []byte) bool {
-	if tr.err != nil {
-		return false
-	}
-
-	var p parser
-	given := p.parseOctal(header[148:156])
-	unsigned, signed := checksum(header)
-	return p.err == nil && (given == unsigned || given == signed)
-}
-
 // readHeader reads the next block header and assumes that the underlying reader
 // is already aligned to a block boundary.
 //
@@ -562,19 +539,16 @@ func (tr *Reader) verifyChecksum(header []byte) bool {
 //	* Exactly 1 block of zeros is read and EOF is hit.
 //	* At least 2 blocks of zeros are read.
 func (tr *Reader) readHeader() *Header {
-	header := tr.hdrBuff[:]
-	copy(header, zeroBlock)
-
-	if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
+	if _, tr.err = io.ReadFull(tr.r, tr.blk[:]); tr.err != nil {
 		return nil // io.EOF is okay here
 	}
 
 	// Two blocks of zero bytes marks the end of the archive.
-	if bytes.Equal(header, zeroBlock[0:blockSize]) {
-		if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
+	if bytes.Equal(tr.blk[:], zeroBlock[:]) {
+		if _, tr.err = io.ReadFull(tr.r, tr.blk[:]); tr.err != nil {
 			return nil // io.EOF is okay here
 		}
-		if bytes.Equal(header, zeroBlock[0:blockSize]) {
+		if bytes.Equal(tr.blk[:], zeroBlock[:]) {
 			tr.err = io.EOF
 		} else {
 			tr.err = ErrHeader // zero block and then non-zero block
@@ -582,71 +556,55 @@ func (tr *Reader) readHeader() *Header {
 		return nil
 	}
 
-	if !tr.verifyChecksum(header) {
+	// Verify the header matches a known format.
+	format := tr.blk.GetFormat()
+	if format == formatUnknown {
 		tr.err = ErrHeader
 		return nil
 	}
 
-	// Unpack
 	var p parser
 	hdr := new(Header)
-	s := slicer(header)
-
-	hdr.Name = p.parseString(s.next(100))
-	hdr.Mode = p.parseNumeric(s.next(8))
-	hdr.Uid = int(p.parseNumeric(s.next(8)))
-	hdr.Gid = int(p.parseNumeric(s.next(8)))
-	hdr.Size = p.parseNumeric(s.next(12))
-	hdr.ModTime = time.Unix(p.parseNumeric(s.next(12)), 0)
-	s.next(8) // chksum
-	hdr.Typeflag = s.next(1)[0]
-	hdr.Linkname = p.parseString(s.next(100))
-
-	// The remainder of the header depends on the value of magic.
-	// The original (v7) version of tar had no explicit magic field,
-	// so its magic bytes, like the rest of the block, are NULs.
-	magic := string(s.next(8)) // contains version field as well.
-	var format string
-	switch {
-	case magic[:6] == "ustar\x00": // POSIX tar (1003.1-1988)
-		if string(header[508:512]) == "tar\x00" {
-			format = "star"
-		} else {
-			format = "posix"
-		}
-	case magic == "ustar  \x00": // old GNU tar
-		format = "gnu"
-	}
 
-	switch format {
-	case "posix", "gnu", "star":
-		hdr.Uname = p.parseString(s.next(32))
-		hdr.Gname = p.parseString(s.next(32))
-		devmajor := s.next(8)
-		devminor := s.next(8)
+	// Unpack the V7 header.
+	v7 := tr.blk.V7()
+	hdr.Name = p.parseString(v7.Name())
+	hdr.Mode = p.parseNumeric(v7.Mode())
+	hdr.Uid = int(p.parseNumeric(v7.UID()))
+	hdr.Gid = int(p.parseNumeric(v7.GID()))
+	hdr.Size = p.parseNumeric(v7.Size())
+	hdr.ModTime = time.Unix(p.parseNumeric(v7.ModTime()), 0)
+	hdr.Typeflag = v7.TypeFlag()[0]
+	hdr.Linkname = p.parseString(v7.LinkName())
+
+	// Unpack format specific fields.
+	if format > formatV7 {
+		ustar := tr.blk.USTAR()
+		hdr.Uname = p.parseString(ustar.UserName())
+		hdr.Gname = p.parseString(ustar.GroupName())
 		if hdr.Typeflag == TypeChar || hdr.Typeflag == TypeBlock {
-			hdr.Devmajor = p.parseNumeric(devmajor)
-			hdr.Devminor = p.parseNumeric(devminor)
+			hdr.Devmajor = p.parseNumeric(ustar.DevMajor())
+			hdr.Devminor = p.parseNumeric(ustar.DevMinor())
 		}
+
 		var prefix string
 		switch format {
-		case "posix", "gnu":
-			prefix = p.parseString(s.next(155))
-		case "star":
-			prefix = p.parseString(s.next(131))
-			hdr.AccessTime = time.Unix(p.parseNumeric(s.next(12)), 0)
-			hdr.ChangeTime = time.Unix(p.parseNumeric(s.next(12)), 0)
+		case formatUSTAR, formatGNU:
+			// TODO(dsnet): Do not use the prefix field for the GNU format!
+			// See golang.org/issues/12594
+			ustar := tr.blk.USTAR()
+			prefix = p.parseString(ustar.Prefix())
+		case formatSTAR:
+			star := tr.blk.STAR()
+			prefix = p.parseString(star.Prefix())
+			hdr.AccessTime = time.Unix(p.parseNumeric(star.AccessTime()), 0)
+			hdr.ChangeTime = time.Unix(p.parseNumeric(star.ChangeTime()), 0)
 		}
 		if len(prefix) > 0 {
 			hdr.Name = prefix + "/" + hdr.Name
 		}
 	}
 
-	if p.err != nil {
-		tr.err = p.err
-		return nil
-	}
-
 	nb := hdr.Size
 	if isHeaderOnlyType(hdr.Typeflag) {
 		nb = 0
@@ -663,14 +621,14 @@ func (tr *Reader) readHeader() *Header {
 	// Check for old GNU sparse format entry.
 	if hdr.Typeflag == TypeGNUSparse {
 		// Get the real size of the file.
-		hdr.Size = p.parseNumeric(header[483:495])
+		hdr.Size = p.parseNumeric(tr.blk.GNU().RealSize())
 		if p.err != nil {
 			tr.err = p.err
 			return nil
 		}
 
 		// Read the sparse map.
-		sp := tr.readOldGNUSparseMap(header)
+		sp := tr.readOldGNUSparseMap(&tr.blk)
 		if tr.err != nil {
 			return nil
 		}
@@ -682,26 +640,24 @@ func (tr *Reader) readHeader() *Header {
 		}
 	}
 
+	if p.err != nil {
+		tr.err = p.err
+		return nil
+	}
+
 	return hdr
 }
 
 // readOldGNUSparseMap reads the sparse map as stored in the old GNU sparse format.
 // The sparse map is stored in the tar header if it's small enough. If it's larger than four entries,
 // then one or more extension headers are used to store the rest of the sparse map.
-func (tr *Reader) readOldGNUSparseMap(header []byte) []sparseEntry {
+func (tr *Reader) readOldGNUSparseMap(blk *block) []sparseEntry {
 	var p parser
-	isExtended := header[oldGNUSparseMainHeaderIsExtendedOffset] != 0
-	spCap := oldGNUSparseMainHeaderNumEntries
-	if isExtended {
-		spCap += oldGNUSparseExtendedHeaderNumEntries
-	}
-	sp := make([]sparseEntry, 0, spCap)
-	s := slicer(header[oldGNUSparseMainHeaderOffset:])
-
-	// Read the four entries from the main tar header
-	for i := 0; i < oldGNUSparseMainHeaderNumEntries; i++ {
-		offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize))
-		numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize))
+	var s sparseArray = blk.GNU().Sparse()
+	var sp = make([]sparseEntry, 0, s.MaxEntries())
+	for i := 0; i < s.MaxEntries(); i++ {
+		offset := p.parseOctal(s.Entry(i).Offset())
+		numBytes := p.parseOctal(s.Entry(i).NumBytes())
 		if p.err != nil {
 			tr.err = p.err
 			return nil
@@ -712,17 +668,17 @@ func (tr *Reader) readOldGNUSparseMap(header []byte) []sparseEntry {
 		sp = append(sp, sparseEntry{offset: offset, numBytes: numBytes})
 	}
 
-	for isExtended {
+	for s.IsExtended()[0] > 0 {
 		// There are more entries. Read an extension header and parse its entries.
-		sparseHeader := make([]byte, blockSize)
-		if _, tr.err = io.ReadFull(tr.r, sparseHeader); tr.err != nil {
+		var blk block
+		if _, tr.err = io.ReadFull(tr.r, blk[:]); tr.err != nil {
 			return nil
 		}
-		isExtended = sparseHeader[oldGNUSparseExtendedHeaderIsExtendedOffset] != 0
-		s = slicer(sparseHeader)
-		for i := 0; i < oldGNUSparseExtendedHeaderNumEntries; i++ {
-			offset := p.parseNumeric(s.next(oldGNUSparseOffsetSize))
-			numBytes := p.parseNumeric(s.next(oldGNUSparseNumBytesSize))
+		s = blk.Sparse()
+
+		for i := 0; i < s.MaxEntries(); i++ {
+			offset := p.parseOctal(s.Entry(i).Offset())
+			numBytes := p.parseOctal(s.Entry(i).NumBytes())
 			if p.err != nil {
 				tr.err = p.err
 				return nil
diff --git a/libgo/go/archive/tar/writer.go b/libgo/go/archive/tar/writer.go
index 042638175cd..426e4434eb7 100644
--- a/libgo/go/archive/tar/writer.go
+++ b/libgo/go/archive/tar/writer.go
@@ -36,10 +36,10 @@ type Writer struct {
 	nb         int64 // number of unwritten bytes for current file entry
 	pad        int64 // amount of padding to write after current file entry
 	closed     bool
-	usedBinary bool            // whether the binary numeric field extension was used
-	preferPax  bool            // use pax header instead of binary numeric header
-	hdrBuff    [blockSize]byte // buffer to use in writeHeader when writing a regular header
-	paxHdrBuff [blockSize]byte // buffer to use in writeHeader when writing a pax header
+	usedBinary bool  // whether the binary numeric field extension was used
+	preferPax  bool  // use PAX header instead of binary numeric header
+	hdrBuff    block // buffer to use in writeHeader when writing a regular header
+	paxHdrBuff block // buffer to use in writeHeader when writing a PAX header
 }
 
 type formatter struct {
@@ -153,27 +153,24 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 	// a map to hold pax header records, if any are needed
 	paxHeaders := make(map[string]string)
 
-	// TODO(shanemhansen): we might want to use PAX headers for
+	// TODO(dsnet): we might want to use PAX headers for
 	// subsecond time resolution, but for now let's just capture
 	// too long fields or non ascii characters
 
-	var f formatter
-	var header []byte
-
 	// We need to select which scratch buffer to use carefully,
 	// since this method is called recursively to write PAX headers.
 	// If allowPax is true, this is the non-recursive call, and we will use hdrBuff.
 	// If allowPax is false, we are being called by writePAXHeader, and hdrBuff is
 	// already being used by the non-recursive call, so we must use paxHdrBuff.
-	header = tw.hdrBuff[:]
+	header := &tw.hdrBuff
 	if !allowPax {
-		header = tw.paxHdrBuff[:]
+		header = &tw.paxHdrBuff
 	}
-	copy(header, zeroBlock)
-	s := slicer(header)
+	copy(header[:], zeroBlock[:])
 
 	// Wrappers around formatter that automatically sets paxHeaders if the
 	// argument extends beyond the capacity of the input byte slice.
+	var f formatter
 	var formatString = func(b []byte, s string, paxKeyword string) {
 		needsPaxHeader := paxKeyword != paxNone && len(s) > len(b) || !isASCII(s)
 		if needsPaxHeader {
@@ -202,44 +199,33 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 		f.formatNumeric(b, x)
 	}
 
-	// keep a reference to the filename to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
-	pathHeaderBytes := s.next(fileNameSize)
-
-	formatString(pathHeaderBytes, hdr.Name, paxPath)
-
 	// Handle out of range ModTime carefully.
 	var modTime int64
 	if !hdr.ModTime.Before(minTime) && !hdr.ModTime.After(maxTime) {
 		modTime = hdr.ModTime.Unix()
 	}
 
-	f.formatOctal(s.next(8), hdr.Mode)               // 100:108
-	formatNumeric(s.next(8), int64(hdr.Uid), paxUid) // 108:116
-	formatNumeric(s.next(8), int64(hdr.Gid), paxGid) // 116:124
-	formatNumeric(s.next(12), hdr.Size, paxSize)     // 124:136
-	formatNumeric(s.next(12), modTime, paxNone)      // 136:148 --- consider using pax for finer granularity
-	s.next(8)                                        // chksum (148:156)
-	s.next(1)[0] = hdr.Typeflag                      // 156:157
-
-	formatString(s.next(100), hdr.Linkname, paxLinkpath)
-
-	copy(s.next(8), []byte("ustar\x0000"))          // 257:265
-	formatString(s.next(32), hdr.Uname, paxUname)   // 265:297
-	formatString(s.next(32), hdr.Gname, paxGname)   // 297:329
-	formatNumeric(s.next(8), hdr.Devmajor, paxNone) // 329:337
-	formatNumeric(s.next(8), hdr.Devminor, paxNone) // 337:345
-
-	// keep a reference to the prefix to allow to overwrite it later if we detect that we can use ustar longnames instead of pax
-	prefixHeaderBytes := s.next(155)
-	formatString(prefixHeaderBytes, "", paxNone) // 345:500  prefix
+	v7 := header.V7()
+	formatString(v7.Name(), hdr.Name, paxPath)
+	// TODO(dsnet): The GNU format permits the mode field to be encoded in
+	// base-256 format. Thus, we can use formatNumeric instead of formatOctal.
+	f.formatOctal(v7.Mode(), hdr.Mode)
+	formatNumeric(v7.UID(), int64(hdr.Uid), paxUid)
+	formatNumeric(v7.GID(), int64(hdr.Gid), paxGid)
+	formatNumeric(v7.Size(), hdr.Size, paxSize)
+	// TODO(dsnet): Consider using PAX for finer time granularity.
+	formatNumeric(v7.ModTime(), modTime, paxNone)
+	v7.TypeFlag()[0] = hdr.Typeflag
+	formatString(v7.LinkName(), hdr.Linkname, paxLinkpath)
+
+	ustar := header.USTAR()
+	formatString(ustar.UserName(), hdr.Uname, paxUname)
+	formatString(ustar.GroupName(), hdr.Gname, paxGname)
+	formatNumeric(ustar.DevMajor(), hdr.Devmajor, paxNone)
+	formatNumeric(ustar.DevMinor(), hdr.Devminor, paxNone)
 
-	// Use the GNU magic instead of POSIX magic if we used any GNU extensions.
-	if tw.usedBinary {
-		copy(header[257:265], []byte("ustar  \x00"))
-	}
-
-	_, paxPathUsed := paxHeaders[paxPath]
 	// try to use a ustar header when only the name is too long
+	_, paxPathUsed := paxHeaders[paxPath]
 	if !tw.preferPax && len(paxHeaders) == 1 && paxPathUsed {
 		prefix, suffix, ok := splitUSTARPath(hdr.Name)
 		if ok {
@@ -247,16 +233,16 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 			delete(paxHeaders, paxPath)
 
 			// Update the path fields
-			formatString(pathHeaderBytes, suffix, paxNone)
-			formatString(prefixHeaderBytes, prefix, paxNone)
+			formatString(v7.Name(), suffix, paxNone)
+			formatString(ustar.Prefix(), prefix, paxNone)
 		}
 	}
 
-	// The chksum field is terminated by a NUL and a space.
-	// This is different from the other octal fields.
-	chksum, _ := checksum(header)
-	f.formatOctal(header[148:155], chksum) // Never fails
-	header[155] = ' '
+	if tw.usedBinary {
+		header.SetFormat(formatGNU)
+	} else {
+		header.SetFormat(formatUSTAR)
+	}
 
 	// Check if there were any formatting errors.
 	if f.err != nil {
@@ -278,10 +264,10 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 			return err
 		}
 	}
-	tw.nb = int64(hdr.Size)
+	tw.nb = hdr.Size
 	tw.pad = (blockSize - (tw.nb % blockSize)) % blockSize
 
-	_, tw.err = tw.w.Write(header)
+	_, tw.err = tw.w.Write(header[:])
 	return tw.err
 }
 
@@ -289,10 +275,10 @@ func (tw *Writer) writeHeader(hdr *Header, allowPax bool) error {
 // If the path is not splittable, then it will return ("", "", false).
 func splitUSTARPath(name string) (prefix, suffix string, ok bool) {
 	length := len(name)
-	if length <= fileNameSize || !isASCII(name) {
+	if length <= nameSize || !isASCII(name) {
 		return "", "", false
-	} else if length > fileNamePrefixSize+1 {
-		length = fileNamePrefixSize + 1
+	} else if length > prefixSize+1 {
+		length = prefixSize + 1
 	} else if name[length-1] == '/' {
 		length--
 	}
@@ -300,7 +286,7 @@ func splitUSTARPath(name string) (prefix, suffix string, ok bool) {
 	i := strings.LastIndex(name[:length], "/")
 	nlen := len(name) - i - 1 // nlen is length of suffix
 	plen := i                 // plen is length of prefix
-	if i <= 0 || nlen > fileNameSize || nlen == 0 || plen > fileNamePrefixSize {
+	if i <= 0 || nlen > nameSize || nlen == 0 || plen > prefixSize {
 		return "", "", false
 	}
 	return name[:i], name[i+1:], true
@@ -316,15 +302,15 @@ func (tw *Writer) writePAXHeader(hdr *Header, paxHeaders map[string]string) erro
 	// succeed, and seems harmless enough.
 	ext.ModTime = hdr.ModTime
 	// The spec asks that we namespace our pseudo files
-	// with the current pid.  However, this results in differing outputs
-	// for identical inputs.  As such, the constant 0 is now used instead.
+	// with the current pid. However, this results in differing outputs
+	// for identical inputs. As such, the constant 0 is now used instead.
 	// golang.org/issue/12358
 	dir, file := path.Split(hdr.Name)
 	fullName := path.Join(dir, "PaxHeaders.0", file)
 
 	ascii := toASCII(fullName)
-	if len(ascii) > 100 {
-		ascii = ascii[:100]
+	if len(ascii) > nameSize {
+		ascii = ascii[:nameSize]
 	}
 	ext.Name = ascii
 	// Construct the body
@@ -407,7 +393,7 @@ func (tw *Writer) Close() error {
 
 	// trailer: two zero blocks
 	for i := 0; i < 2; i++ {
-		_, tw.err = tw.w.Write(zeroBlock)
+		_, tw.err = tw.w.Write(zeroBlock[:])
 		if tw.err != nil {
 			break
 		}
diff --git a/libgo/go/archive/tar/writer_test.go b/libgo/go/archive/tar/writer_test.go
index 6e91d907ce9..27aa8e5dab6 100644
--- a/libgo/go/archive/tar/writer_test.go
+++ b/libgo/go/archive/tar/writer_test.go
@@ -587,17 +587,17 @@ func TestSplitUSTARPath(t *testing.T) {
 		{"", "", "", false},
 		{"abc", "", "", false},
 		{"用戶名", "", "", false},
-		{sr("a", fileNameSize), "", "", false},
-		{sr("a", fileNameSize) + "/", "", "", false},
-		{sr("a", fileNameSize) + "/a", sr("a", fileNameSize), "a", true},
-		{sr("a", fileNamePrefixSize) + "/", "", "", false},
-		{sr("a", fileNamePrefixSize) + "/a", sr("a", fileNamePrefixSize), "a", true},
-		{sr("a", fileNameSize+1), "", "", false},
-		{sr("/", fileNameSize+1), sr("/", fileNameSize-1), "/", true},
-		{sr("a", fileNamePrefixSize) + "/" + sr("b", fileNameSize),
-			sr("a", fileNamePrefixSize), sr("b", fileNameSize), true},
-		{sr("a", fileNamePrefixSize) + "//" + sr("b", fileNameSize), "", "", false},
-		{sr("a/", fileNameSize), sr("a/", 77) + "a", sr("a/", 22), true},
+		{sr("a", nameSize), "", "", false},
+		{sr("a", nameSize) + "/", "", "", false},
+		{sr("a", nameSize) + "/a", sr("a", nameSize), "a", true},
+		{sr("a", prefixSize) + "/", "", "", false},
+		{sr("a", prefixSize) + "/a", sr("a", prefixSize), "a", true},
+		{sr("a", nameSize+1), "", "", false},
+		{sr("/", nameSize+1), sr("/", nameSize-1), "/", true},
+		{sr("a", prefixSize) + "/" + sr("b", nameSize),
+			sr("a", prefixSize), sr("b", nameSize), true},
+		{sr("a", prefixSize) + "//" + sr("b", nameSize), "", "", false},
+		{sr("a/", nameSize), sr("a/", 77) + "a", sr("a/", 22), true},
 	}
 
 	for _, v := range vectors {
diff --git a/libgo/go/archive/zip/reader.go b/libgo/go/archive/zip/reader.go
index 10e81728757..f6c3ead3bea 100644
--- a/libgo/go/archive/zip/reader.go
+++ b/libgo/go/archive/zip/reader.go
@@ -87,7 +87,7 @@ func (z *Reader) init(r io.ReaderAt, size int64) error {
 	z.File = make([]*File, 0, end.directoryRecords)
 	z.Comment = end.comment
 	rs := io.NewSectionReader(r, 0, size)
-	if _, err = rs.Seek(int64(end.directoryOffset), os.SEEK_SET); err != nil {
+	if _, err = rs.Seek(int64(end.directoryOffset), io.SeekStart); err != nil {
 		return err
 	}
 	buf := bufio.NewReader(rs)
@@ -153,19 +153,18 @@ func (f *File) DataOffset() (offset int64, err error) {
 
 // Open returns a ReadCloser that provides access to the File's contents.
 // Multiple files may be read concurrently.
-func (f *File) Open() (rc io.ReadCloser, err error) {
+func (f *File) Open() (io.ReadCloser, error) {
 	bodyOffset, err := f.findBodyOffset()
 	if err != nil {
-		return
+		return nil, err
 	}
 	size := int64(f.CompressedSize64)
 	r := io.NewSectionReader(f.zipr, f.headerOffset+bodyOffset, size)
 	dcomp := f.zip.decompressor(f.Method)
 	if dcomp == nil {
-		err = ErrAlgorithm
-		return
+		return nil, ErrAlgorithm
 	}
-	rc = dcomp(r)
+	var rc io.ReadCloser = dcomp(r)
 	var desr io.Reader
 	if f.hasDataDescriptor() {
 		desr = io.NewSectionReader(f.zipr, f.headerOffset+bodyOffset+size, dataDescriptorLen)
@@ -176,7 +175,7 @@ func (f *File) Open() (rc io.ReadCloser, err error) {
 		f:    f,
 		desr: desr,
 	}
-	return
+	return rc, nil
 }
 
 type checksumReader struct {
diff --git a/libgo/go/archive/zip/reader_test.go b/libgo/go/archive/zip/reader_test.go
index 72cf5d9cf42..dfaae784361 100644
--- a/libgo/go/archive/zip/reader_test.go
+++ b/libgo/go/archive/zip/reader_test.go
@@ -399,7 +399,7 @@ func readTestFile(t *testing.T, zt ZipTest, ft ZipTestFile, f *File) {
 	// Don't bother uncompressing: too big.
 	if ft.Content == nil && ft.File == "" && ft.Size > 0 {
 		if size != ft.Size {
-			t.Errorf("%v: uncompressed size %#x, want %#x", size, ft.Size)
+			t.Errorf("%v: uncompressed size %#x, want %#x", ft.Name, size, ft.Size)
 		}
 		r.Close()
 		return
diff --git a/libgo/go/archive/zip/register.go b/libgo/go/archive/zip/register.go
index 8fccbf7ca09..2e76386b1fd 100644
--- a/libgo/go/archive/zip/register.go
+++ b/libgo/go/archive/zip/register.go
@@ -64,6 +64,44 @@ func (w *pooledFlateWriter) Close() error {
 	return err
 }
 
+var flateReaderPool sync.Pool
+
+func newFlateReader(r io.Reader) io.ReadCloser {
+	fr, ok := flateReaderPool.Get().(io.ReadCloser)
+	if ok {
+		fr.(flate.Resetter).Reset(r, nil)
+	} else {
+		fr = flate.NewReader(r)
+	}
+	return &pooledFlateReader{fr: fr}
+}
+
+type pooledFlateReader struct {
+	mu sync.Mutex // guards Close and Read
+	fr io.ReadCloser
+}
+
+func (r *pooledFlateReader) Read(p []byte) (n int, err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.fr == nil {
+		return 0, errors.New("Read after Close")
+	}
+	return r.fr.Read(p)
+}
+
+func (r *pooledFlateReader) Close() error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	var err error
+	if r.fr != nil {
+		err = r.fr.Close()
+		flateReaderPool.Put(r.fr)
+		r.fr = nil
+	}
+	return err
+}
+
 var (
 	mu sync.RWMutex // guards compressor and decompressor maps
 
@@ -74,7 +112,7 @@ var (
 
 	decompressors = map[uint16]Decompressor{
 		Store:   ioutil.NopCloser,
-		Deflate: flate.NewReader,
+		Deflate: newFlateReader,
 	}
 )
 
diff --git a/libgo/go/archive/zip/struct.go b/libgo/go/archive/zip/struct.go
index 5ee4f88f803..e92d02f8a2e 100644
--- a/libgo/go/archive/zip/struct.go
+++ b/libgo/go/archive/zip/struct.go
@@ -5,7 +5,7 @@
 /*
 Package zip provides support for reading and writing ZIP archives.
 
-See: http://www.pkware.com/documents/casestudies/APPNOTE.TXT
+See: https://www.pkware.com/documents/casestudies/APPNOTE.TXT
 
 This package does not support disk spanning.
 
diff --git a/libgo/go/archive/zip/writer.go b/libgo/go/archive/zip/writer.go
index 5ce66e6be5e..3a9292e3807 100644
--- a/libgo/go/archive/zip/writer.go
+++ b/libgo/go/archive/zip/writer.go
@@ -52,7 +52,7 @@ func (w *Writer) Flush() error {
 }
 
 // Close finishes writing the zip file by writing the central directory.
-// It does not (and can not) close the underlying writer.
+// It does not (and cannot) close the underlying writer.
 func (w *Writer) Close() error {
 	if w.last != nil && !w.last.closed {
 		if err := w.last.close(); err != nil {
diff --git a/libgo/go/archive/zip/writer_test.go b/libgo/go/archive/zip/writer_test.go
index 01b63f2358d..86841c755f1 100644
--- a/libgo/go/archive/zip/writer_test.go
+++ b/libgo/go/archive/zip/writer_test.go
@@ -184,7 +184,7 @@ func BenchmarkCompressedZipGarbage(b *testing.B) {
 	b.ReportAllocs()
 	var buf bytes.Buffer
 	bigBuf := bytes.Repeat([]byte("a"), 1<<20)
-	for i := 0; i < b.N; i++ {
+	for i := 0; i <= b.N; i++ {
 		buf.Reset()
 		zw := NewWriter(&buf)
 		for j := 0; j < 3; j++ {
@@ -195,5 +195,11 @@ func BenchmarkCompressedZipGarbage(b *testing.B) {
 			w.Write(bigBuf)
 		}
 		zw.Close()
+		if i == 0 {
+			// Reset the timer after the first time through.
+			// This effectively discards the very large initial flate setup cost,
+			// as well as the initialization of bigBuf.
+			b.ResetTimer()
+		}
 	}
 }
diff --git a/libgo/go/archive/zip/zip_test.go b/libgo/go/archive/zip/zip_test.go
index f785abf50aa..3a3c915d34e 100644
--- a/libgo/go/archive/zip/zip_test.go
+++ b/libgo/go/archive/zip/zip_test.go
@@ -366,27 +366,6 @@ func testZip64DirectoryRecordLength(buf *rleBuffer, t *testing.T) {
 	}
 }
 
-func testInvalidHeader(h *FileHeader, t *testing.T) {
-	var buf bytes.Buffer
-	z := NewWriter(&buf)
-
-	f, err := z.CreateHeader(h)
-	if err != nil {
-		t.Fatalf("error creating header: %v", err)
-	}
-	if _, err := f.Write([]byte("hi")); err != nil {
-		t.Fatalf("error writing content: %v", err)
-	}
-	if err := z.Close(); err != nil {
-		t.Fatalf("error closing zip writer: %v", err)
-	}
-
-	b := buf.Bytes()
-	if _, err = NewReader(bytes.NewReader(b), int64(len(b))); err != ErrFormat {
-		t.Fatalf("got %v, expected ErrFormat", err)
-	}
-}
-
 func testValidHeader(h *FileHeader, t *testing.T) {
 	var buf bytes.Buffer
 	z := NewWriter(&buf)
diff --git a/libgo/go/bufio/bufio.go b/libgo/go/bufio/bufio.go
index 6a70f7034d0..3b30b8b80cd 100644
--- a/libgo/go/bufio/bufio.go
+++ b/libgo/go/bufio/bufio.go
@@ -124,14 +124,16 @@ func (b *Reader) Peek(n int) ([]byte, error) {
 	if n < 0 {
 		return nil, ErrNegativeCount
 	}
-	if n > len(b.buf) {
-		return nil, ErrBufferFull
-	}
-	// 0 <= n <= len(b.buf)
-	for b.w-b.r < n && b.err == nil {
+
+	for b.w-b.r < n && b.w-b.r < len(b.buf) && b.err == nil {
 		b.fill() // b.w-b.r < len(b.buf) => buffer is not full
 	}
 
+	if n > len(b.buf) {
+		return b.buf[b.r:b.w], ErrBufferFull
+	}
+
+	// 0 <= n <= len(b.buf)
 	var err error
 	if avail := b.w - b.r; avail < n {
 		// not enough data in buffer
@@ -220,7 +222,7 @@ func (b *Reader) Read(p []byte) (n int, err error) {
 
 // ReadByte reads and returns a single byte.
 // If no byte is available, returns an error.
-func (b *Reader) ReadByte() (c byte, err error) {
+func (b *Reader) ReadByte() (byte, error) {
 	b.lastRuneSize = -1
 	for b.r == b.w {
 		if b.err != nil {
@@ -228,13 +230,13 @@ func (b *Reader) ReadByte() (c byte, err error) {
 		}
 		b.fill() // buffer is empty
 	}
-	c = b.buf[b.r]
+	c := b.buf[b.r]
 	b.r++
 	b.lastByte = int(c)
 	return c, nil
 }
 
-// UnreadByte unreads the last byte.  Only the most recently read byte can be unread.
+// UnreadByte unreads the last byte. Only the most recently read byte can be unread.
 func (b *Reader) UnreadByte() error {
 	if b.lastByte < 0 || b.r == 0 && b.w > 0 {
 		return ErrInvalidUnreadByte
@@ -264,7 +266,7 @@ func (b *Reader) ReadRune() (r rune, size int, err error) {
 		return 0, 0, b.readErr()
 	}
 	r, size = rune(b.buf[b.r]), 1
-	if r >= 0x80 {
+	if r >= utf8.RuneSelf {
 		r, size = utf8.DecodeRune(b.buf[b.r:b.w])
 	}
 	b.r += size
@@ -273,7 +275,7 @@ func (b *Reader) ReadRune() (r rune, size int, err error) {
 	return r, size, nil
 }
 
-// UnreadRune unreads the last rune.  If the most recent read operation on
+// UnreadRune unreads the last rune. If the most recent read operation on
 // the buffer was not a ReadRune, UnreadRune returns an error.  (In this
 // regard it is stricter than UnreadByte, which will unread the last byte
 // from any read operation.)
@@ -395,12 +397,12 @@ func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error) {
 // ReadBytes returns err != nil if and only if the returned data does not end in
 // delim.
 // For simple uses, a Scanner may be more convenient.
-func (b *Reader) ReadBytes(delim byte) (line []byte, err error) {
+func (b *Reader) ReadBytes(delim byte) ([]byte, error) {
 	// Use ReadSlice to look for array,
 	// accumulating full buffers.
 	var frag []byte
 	var full [][]byte
-
+	var err error
 	for {
 		var e error
 		frag, e = b.ReadSlice(delim)
@@ -442,10 +444,9 @@ func (b *Reader) ReadBytes(delim byte) (line []byte, err error) {
 // ReadString returns err != nil if and only if the returned data does not end in
 // delim.
 // For simple uses, a Scanner may be more convenient.
-func (b *Reader) ReadString(delim byte) (line string, err error) {
+func (b *Reader) ReadString(delim byte) (string, error) {
 	bytes, err := b.ReadBytes(delim)
-	line = string(bytes)
-	return line, err
+	return string(bytes), err
 }
 
 // WriteTo implements io.WriterTo.
@@ -705,7 +706,7 @@ func (b *Writer) ReadFrom(r io.Reader) (n int64, err error) {
 		}
 	}
 	if err == io.EOF {
-		// If we filled the buffer exactly, flush pre-emptively.
+		// If we filled the buffer exactly, flush preemptively.
 		if b.Available() == 0 {
 			err = b.flush()
 		} else {
diff --git a/libgo/go/bufio/bufio_test.go b/libgo/go/bufio/bufio_test.go
index 666c44e15a9..858048696e4 100644
--- a/libgo/go/bufio/bufio_test.go
+++ b/libgo/go/bufio/bufio_test.go
@@ -673,8 +673,8 @@ func TestPeek(t *testing.T) {
 	if _, err := buf.Peek(-1); err != ErrNegativeCount {
 		t.Fatalf("want ErrNegativeCount got %v", err)
 	}
-	if _, err := buf.Peek(32); err != ErrBufferFull {
-		t.Fatalf("want ErrBufFull got %v", err)
+	if s, err := buf.Peek(32); string(s) != "abcdefghijklmnop" || err != ErrBufferFull {
+		t.Fatalf("want %q, ErrBufFull got %q, err=%v", "abcdefghijklmnop", string(s), err)
 	}
 	if _, err := buf.Read(p[0:3]); string(p[0:3]) != "abc" || err != nil {
 		t.Fatalf("want %q got %q, err=%v", "abc", string(p[0:3]), err)
@@ -1475,7 +1475,7 @@ func BenchmarkReaderWriteToOptimal(b *testing.B) {
 		b.Fatal("ioutil.Discard doesn't support ReaderFrom")
 	}
 	for i := 0; i < b.N; i++ {
-		r.Seek(0, 0)
+		r.Seek(0, io.SeekStart)
 		srcReader.Reset(onlyReader{r})
 		n, err := srcReader.WriteTo(ioutil.Discard)
 		if err != nil {
diff --git a/libgo/go/bufio/scan_test.go b/libgo/go/bufio/scan_test.go
index 07b1a56dc0a..1bb1e883932 100644
--- a/libgo/go/bufio/scan_test.go
+++ b/libgo/go/bufio/scan_test.go
@@ -264,10 +264,6 @@ func testNoNewline(text string, lines []string, t *testing.T) {
 	}
 }
 
-var noNewlineLines = []string{
-	"abcdefghijklmn\nopqrstuvwxyz",
-}
-
 // Test that the line splitter handles a final line without a newline.
 func TestScanLineNoNewline(t *testing.T) {
 	const text = "abcdefghijklmn\nopqrstuvwxyz"
@@ -351,7 +347,7 @@ func TestSplitError(t *testing.T) {
 // Test that an EOF is overridden by a user-generated scan error.
 func TestErrAtEOF(t *testing.T) {
 	s := NewScanner(strings.NewReader("1 2 33"))
-	// This spitter will fail on last entry, after s.err==EOF.
+	// This splitter will fail on last entry, after s.err==EOF.
 	split := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
 		advance, token, err = ScanWords(data, atEOF)
 		if len(token) > 1 {
diff --git a/libgo/go/bytes/buffer.go b/libgo/go/bytes/buffer.go
index ddaba3bff35..9154a1b9545 100644
--- a/libgo/go/bytes/buffer.go
+++ b/libgo/go/bytes/buffer.go
@@ -17,8 +17,8 @@ import (
 type Buffer struct {
 	buf       []byte            // contents are the bytes buf[off : len(buf)]
 	off       int               // read at &buf[off], write at &buf[len(buf)]
-	runeBytes [utf8.UTFMax]byte // avoid allocation of slice on each WriteByte or Rune
-	bootstrap [64]byte          // memory to hold first slice; helps small buffers (Printf) avoid allocation.
+	runeBytes [utf8.UTFMax]byte // avoid allocation of slice on each call to WriteRune
+	bootstrap [64]byte          // memory to hold first slice; helps small buffers avoid allocation.
 	lastRead  readOp            // last read operation, so that Unread* can work correctly.
 }
 
@@ -44,7 +44,7 @@ var ErrTooLarge = errors.New("bytes.Buffer: too large")
 func (b *Buffer) Bytes() []byte { return b.buf[b.off:] }
 
 // String returns the contents of the unread portion of the buffer
-// as a string.  If the Buffer is a nil pointer, it returns "<nil>".
+// as a string. If the Buffer is a nil pointer, it returns "<nil>".
 func (b *Buffer) String() string {
 	if b == nil {
 		// Special case, useful in debugging.
@@ -145,7 +145,7 @@ func (b *Buffer) WriteString(s string) (n int, err error) {
 }
 
 // MinRead is the minimum slice size passed to a Read call by
-// Buffer.ReadFrom.  As long as the Buffer has at least MinRead bytes beyond
+// Buffer.ReadFrom. As long as the Buffer has at least MinRead bytes beyond
 // what is required to hold the contents of r, ReadFrom will not grow the
 // underlying buffer.
 const MinRead = 512
@@ -252,7 +252,7 @@ func (b *Buffer) WriteRune(r rune) (n int, err error) {
 }
 
 // Read reads the next len(p) bytes from the buffer or until the buffer
-// is drained.  The return value n is the number of bytes read.  If the
+// is drained. The return value n is the number of bytes read. If the
 // buffer has no data to return, err is io.EOF (unless len(p) is zero);
 // otherwise it is nil.
 func (b *Buffer) Read(p []byte) (n int, err error) {
@@ -293,14 +293,14 @@ func (b *Buffer) Next(n int) []byte {
 
 // ReadByte reads and returns the next byte from the buffer.
 // If no byte is available, it returns error io.EOF.
-func (b *Buffer) ReadByte() (c byte, err error) {
+func (b *Buffer) ReadByte() (byte, error) {
 	b.lastRead = opInvalid
 	if b.off >= len(b.buf) {
 		// Buffer is empty, reset to recover space.
 		b.Truncate(0)
 		return 0, io.EOF
 	}
-	c = b.buf[b.off]
+	c := b.buf[b.off]
 	b.off++
 	b.lastRead = opRead
 	return c, nil
@@ -347,7 +347,7 @@ func (b *Buffer) UnreadRune() error {
 }
 
 // UnreadByte unreads the last byte returned by the most recent
-// read operation.  If write has happened since the last read, UnreadByte
+// read operation. If write has happened since the last read, UnreadByte
 // returns an error.
 func (b *Buffer) UnreadByte() error {
 	if b.lastRead != opReadRune && b.lastRead != opRead {
@@ -400,7 +400,7 @@ func (b *Buffer) ReadString(delim byte) (line string, err error) {
 }
 
 // NewBuffer creates and initializes a new Buffer using buf as its initial
-// contents.  It is intended to prepare a Buffer to read existing data.  It
+// contents. It is intended to prepare a Buffer to read existing data. It
 // can also be used to size the internal buffer for writing. To do that,
 // buf should have the desired capacity but a length of zero.
 //
diff --git a/libgo/go/bytes/bytes.go b/libgo/go/bytes/bytes.go
index b86824087e5..305c85d9f41 100644
--- a/libgo/go/bytes/bytes.go
+++ b/libgo/go/bytes/bytes.go
@@ -83,6 +83,16 @@ func Contains(b, subslice []byte) bool {
 	return Index(b, subslice) != -1
 }
 
+// ContainsAny reports whether any of the UTF-8-encoded Unicode code points in chars are within b.
+func ContainsAny(b []byte, chars string) bool {
+	return IndexAny(b, chars) >= 0
+}
+
+// ContainsRune reports whether the Unicode code point r is within b.
+func ContainsRune(b []byte, r rune) bool {
+	return IndexRune(b, r) >= 0
+}
+
 // Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
 func Index(s, sep []byte) int {
 	n := len(sep)
@@ -164,7 +174,7 @@ func IndexRune(s []byte, r rune) int {
 
 // IndexAny interprets s as a sequence of UTF-8-encoded Unicode code points.
 // It returns the byte index of the first occurrence in s of any of the Unicode
-// code points in chars.  It returns -1 if chars is empty or if there is no code
+// code points in chars. It returns -1 if chars is empty or if there is no code
 // point in common.
 func IndexAny(s []byte, chars string) int {
 	if len(chars) > 0 {
@@ -188,8 +198,8 @@ func IndexAny(s []byte, chars string) int {
 }
 
 // LastIndexAny interprets s as a sequence of UTF-8-encoded Unicode code
-// points.  It returns the byte index of the last occurrence in s of any of
-// the Unicode code points in chars.  It returns -1 if chars is empty or if
+// points. It returns the byte index of the last occurrence in s of any of
+// the Unicode code points in chars. It returns -1 if chars is empty or if
 // there is no code point in common.
 func LastIndexAny(s []byte, chars string) int {
 	if len(chars) > 0 {
@@ -276,7 +286,7 @@ func Fields(s []byte) [][]byte {
 
 // FieldsFunc interprets s as a sequence of UTF-8-encoded Unicode code points.
 // It splits the slice s at each run of code points c satisfying f(c) and
-// returns a slice of subslices of s.  If all code points in s satisfy f(c), or
+// returns a slice of subslices of s. If all code points in s satisfy f(c), or
 // len(s) == 0, an empty slice is returned.
 // FieldsFunc makes no guarantees about the order in which it calls f(c).
 // If f does not return consistent results for a given c, FieldsFunc may crash.
@@ -352,12 +362,12 @@ func HasSuffix(s, suffix []byte) bool {
 
 // Map returns a copy of the byte slice s with all its characters modified
 // according to the mapping function. If mapping returns a negative value, the character is
-// dropped from the string with no replacement.  The characters in s and the
+// dropped from the string with no replacement. The characters in s and the
 // output are interpreted as UTF-8-encoded Unicode code points.
 func Map(mapping func(r rune) rune, s []byte) []byte {
 	// In the worst case, the slice can grow when mapped, making
-	// things unpleasant.  But it's so rare we barge in assuming it's
-	// fine.  It could also shrink but that falls out naturally.
+	// things unpleasant. But it's so rare we barge in assuming it's
+	// fine. It could also shrink but that falls out naturally.
 	maxbytes := len(s) // length of b
 	nbytes := 0        // number of bytes encoded in b
 	b := make([]byte, maxbytes)
@@ -697,7 +707,7 @@ func EqualFold(s, t []byte) bool {
 			return false
 		}
 
-		// General case.  SimpleFold(x) returns the next equivalent rune > x
+		// General case. SimpleFold(x) returns the next equivalent rune > x
 		// or wraps around to smaller values.
 		r := unicode.SimpleFold(sr)
 		for r != sr && r < tr {
@@ -709,6 +719,6 @@ func EqualFold(s, t []byte) bool {
 		return false
 	}
 
-	// One string is empty.  Are both?
+	// One string is empty. Are both?
 	return len(s) == len(t)
 }
diff --git a/libgo/go/bytes/bytes_decl.go b/libgo/go/bytes/bytes_decl.go
index b453f21aa43..df0614fed0d 100644
--- a/libgo/go/bytes/bytes_decl.go
+++ b/libgo/go/bytes/bytes_decl.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/bytes/bytes_test.go b/libgo/go/bytes/bytes_test.go
index 8df62fcc6ae..c48f662e10d 100644
--- a/libgo/go/bytes/bytes_test.go
+++ b/libgo/go/bytes/bytes_test.go
@@ -6,6 +6,7 @@ package bytes_test
 
 import (
 	. "bytes"
+	"fmt"
 	"math/rand"
 	"reflect"
 	"testing"
@@ -47,32 +48,6 @@ type BinOpTest struct {
 	i int
 }
 
-var equalTests = []struct {
-	a, b []byte
-	i    int
-}{
-	{[]byte(""), []byte(""), 0},
-	{[]byte("a"), []byte(""), 1},
-	{[]byte(""), []byte("a"), -1},
-	{[]byte("abc"), []byte("abc"), 0},
-	{[]byte("ab"), []byte("abc"), -1},
-	{[]byte("abc"), []byte("ab"), 1},
-	{[]byte("x"), []byte("ab"), 1},
-	{[]byte("ab"), []byte("x"), -1},
-	{[]byte("x"), []byte("a"), 1},
-	{[]byte("b"), []byte("x"), -1},
-	// test runtime·memeq's chunked implementation
-	{[]byte("abcdefgh"), []byte("abcdefgh"), 0},
-	{[]byte("abcdefghi"), []byte("abcdefghi"), 0},
-	{[]byte("abcdefghi"), []byte("abcdefghj"), -1},
-	// nil tests
-	{nil, nil, 0},
-	{[]byte(""), nil, 0},
-	{nil, []byte(""), 0},
-	{[]byte("a"), nil, 1},
-	{nil, []byte("a"), -1},
-}
-
 func TestEqual(t *testing.T) {
 	for _, tt := range compareTests {
 		eql := Equal(tt.a, tt.b)
@@ -113,7 +88,7 @@ func TestEqualExhaustive(t *testing.T) {
 	}
 }
 
-// make sure Equal returns false for minimally different strings.  The data
+// make sure Equal returns false for minimally different strings. The data
 // is all zeros except for a single one in one location.
 func TestNotEqual(t *testing.T) {
 	var size = 128
@@ -335,6 +310,41 @@ func TestIndexByteBig(t *testing.T) {
 	}
 }
 
+// test a small index across all page offsets
+func TestIndexByteSmall(t *testing.T) {
+	b := make([]byte, 5015) // bigger than a page
+	// Make sure we find the correct byte even when straddling a page.
+	for i := 0; i <= len(b)-15; i++ {
+		for j := 0; j < 15; j++ {
+			b[i+j] = byte(100 + j)
+		}
+		for j := 0; j < 15; j++ {
+			p := IndexByte(b[i:i+15], byte(100+j))
+			if p != j {
+				t.Errorf("IndexByte(%q, %d) = %d", b[i:i+15], 100+j, p)
+			}
+		}
+		for j := 0; j < 15; j++ {
+			b[i+j] = 0
+		}
+	}
+	// Make sure matches outside the slice never trigger.
+	for i := 0; i <= len(b)-15; i++ {
+		for j := 0; j < 15; j++ {
+			b[i+j] = 1
+		}
+		for j := 0; j < 15; j++ {
+			p := IndexByte(b[i:i+15], byte(0))
+			if p != -1 {
+				t.Errorf("IndexByte(%q, %d) = %d", b[i:i+15], 0, p)
+			}
+		}
+		for j := 0; j < 15; j++ {
+			b[i+j] = 0
+		}
+	}
+}
+
 func TestIndexRune(t *testing.T) {
 	for _, tt := range indexRuneTests {
 		a := []byte(tt.a)
@@ -348,165 +358,152 @@ func TestIndexRune(t *testing.T) {
 
 var bmbuf []byte
 
-func BenchmarkIndexByte32(b *testing.B)          { bmIndexByte(b, IndexByte, 32) }
-func BenchmarkIndexByte4K(b *testing.B)          { bmIndexByte(b, IndexByte, 4<<10) }
-func BenchmarkIndexByte4M(b *testing.B)          { bmIndexByte(b, IndexByte, 4<<20) }
-func BenchmarkIndexByte64M(b *testing.B)         { bmIndexByte(b, IndexByte, 64<<20) }
-func BenchmarkIndexBytePortable32(b *testing.B)  { bmIndexByte(b, IndexBytePortable, 32) }
-func BenchmarkIndexBytePortable4K(b *testing.B)  { bmIndexByte(b, IndexBytePortable, 4<<10) }
-func BenchmarkIndexBytePortable4M(b *testing.B)  { bmIndexByte(b, IndexBytePortable, 4<<20) }
-func BenchmarkIndexBytePortable64M(b *testing.B) { bmIndexByte(b, IndexBytePortable, 64<<20) }
-
-func bmIndexByte(b *testing.B, index func([]byte, byte) int, n int) {
-	if len(bmbuf) < n {
-		bmbuf = make([]byte, n)
-	}
-	b.SetBytes(int64(n))
-	buf := bmbuf[0:n]
-	buf[n-1] = 'x'
-	for i := 0; i < b.N; i++ {
-		j := index(buf, 'x')
-		if j != n-1 {
-			b.Fatal("bad index", j)
-		}
+func valName(x int) string {
+	if s := x >> 20; s<<20 == x {
+		return fmt.Sprintf("%dM", s)
+	}
+	if s := x >> 10; s<<10 == x {
+		return fmt.Sprintf("%dK", s)
 	}
-	buf[n-1] = '\x00'
+	return fmt.Sprint(x)
 }
 
-func BenchmarkEqual0(b *testing.B) {
-	var buf [4]byte
-	buf1 := buf[0:0]
-	buf2 := buf[1:1]
-	for i := 0; i < b.N; i++ {
-		eq := Equal(buf1, buf2)
-		if !eq {
-			b.Fatal("bad equal")
-		}
-	}
-}
-
-func BenchmarkEqual1(b *testing.B)           { bmEqual(b, Equal, 1) }
-func BenchmarkEqual6(b *testing.B)           { bmEqual(b, Equal, 6) }
-func BenchmarkEqual9(b *testing.B)           { bmEqual(b, Equal, 9) }
-func BenchmarkEqual15(b *testing.B)          { bmEqual(b, Equal, 15) }
-func BenchmarkEqual16(b *testing.B)          { bmEqual(b, Equal, 16) }
-func BenchmarkEqual20(b *testing.B)          { bmEqual(b, Equal, 20) }
-func BenchmarkEqual32(b *testing.B)          { bmEqual(b, Equal, 32) }
-func BenchmarkEqual4K(b *testing.B)          { bmEqual(b, Equal, 4<<10) }
-func BenchmarkEqual4M(b *testing.B)          { bmEqual(b, Equal, 4<<20) }
-func BenchmarkEqual64M(b *testing.B)         { bmEqual(b, Equal, 64<<20) }
-func BenchmarkEqualPort1(b *testing.B)       { bmEqual(b, EqualPortable, 1) }
-func BenchmarkEqualPort6(b *testing.B)       { bmEqual(b, EqualPortable, 6) }
-func BenchmarkEqualPort32(b *testing.B)      { bmEqual(b, EqualPortable, 32) }
-func BenchmarkEqualPort4K(b *testing.B)      { bmEqual(b, EqualPortable, 4<<10) }
-func BenchmarkEqualPortable4M(b *testing.B)  { bmEqual(b, EqualPortable, 4<<20) }
-func BenchmarkEqualPortable64M(b *testing.B) { bmEqual(b, EqualPortable, 64<<20) }
-
-func bmEqual(b *testing.B, equal func([]byte, []byte) bool, n int) {
-	if len(bmbuf) < 2*n {
-		bmbuf = make([]byte, 2*n)
-	}
-	b.SetBytes(int64(n))
-	buf1 := bmbuf[0:n]
-	buf2 := bmbuf[n : 2*n]
-	buf1[n-1] = 'x'
-	buf2[n-1] = 'x'
-	for i := 0; i < b.N; i++ {
-		eq := equal(buf1, buf2)
-		if !eq {
-			b.Fatal("bad equal")
-		}
+func benchBytes(b *testing.B, sizes []int, f func(b *testing.B, n int)) {
+	for _, n := range sizes {
+		b.Run(valName(n), func(b *testing.B) {
+			if len(bmbuf) < n {
+				bmbuf = make([]byte, n)
+			}
+			b.SetBytes(int64(n))
+			f(b, n)
+		})
 	}
-	buf1[n-1] = '\x00'
-	buf2[n-1] = '\x00'
 }
 
-func BenchmarkIndex32(b *testing.B)  { bmIndex(b, Index, 32) }
-func BenchmarkIndex4K(b *testing.B)  { bmIndex(b, Index, 4<<10) }
-func BenchmarkIndex4M(b *testing.B)  { bmIndex(b, Index, 4<<20) }
-func BenchmarkIndex64M(b *testing.B) { bmIndex(b, Index, 64<<20) }
+var indexSizes = []int{10, 32, 4 << 10, 4 << 20, 64 << 20}
 
-func bmIndex(b *testing.B, index func([]byte, []byte) int, n int) {
-	if len(bmbuf) < n {
-		bmbuf = make([]byte, n)
-	}
-	b.SetBytes(int64(n))
-	buf := bmbuf[0:n]
-	buf[n-1] = 'x'
-	for i := 0; i < b.N; i++ {
-		j := index(buf, buf[n-7:])
-		if j != n-7 {
-			b.Fatal("bad index", j)
-		}
-	}
-	buf[n-1] = '\x00'
+func BenchmarkIndexByte(b *testing.B) {
+	benchBytes(b, indexSizes, bmIndexByte(IndexByte))
 }
 
-func BenchmarkIndexEasy32(b *testing.B)  { bmIndexEasy(b, Index, 32) }
-func BenchmarkIndexEasy4K(b *testing.B)  { bmIndexEasy(b, Index, 4<<10) }
-func BenchmarkIndexEasy4M(b *testing.B)  { bmIndexEasy(b, Index, 4<<20) }
-func BenchmarkIndexEasy64M(b *testing.B) { bmIndexEasy(b, Index, 64<<20) }
+func BenchmarkIndexBytePortable(b *testing.B) {
+	benchBytes(b, indexSizes, bmIndexByte(IndexBytePortable))
+}
 
-func bmIndexEasy(b *testing.B, index func([]byte, []byte) int, n int) {
-	if len(bmbuf) < n {
-		bmbuf = make([]byte, n)
-	}
-	b.SetBytes(int64(n))
-	buf := bmbuf[0:n]
-	buf[n-1] = 'x'
-	buf[n-7] = 'x'
-	for i := 0; i < b.N; i++ {
-		j := index(buf, buf[n-7:])
-		if j != n-7 {
-			b.Fatal("bad index", j)
+func bmIndexByte(index func([]byte, byte) int) func(b *testing.B, n int) {
+	return func(b *testing.B, n int) {
+		buf := bmbuf[0:n]
+		buf[n-1] = 'x'
+		for i := 0; i < b.N; i++ {
+			j := index(buf, 'x')
+			if j != n-1 {
+				b.Fatal("bad index", j)
+			}
 		}
+		buf[n-1] = '\x00'
 	}
-	buf[n-1] = '\x00'
-	buf[n-7] = '\x00'
 }
 
-func BenchmarkCount32(b *testing.B)  { bmCount(b, Count, 32) }
-func BenchmarkCount4K(b *testing.B)  { bmCount(b, Count, 4<<10) }
-func BenchmarkCount4M(b *testing.B)  { bmCount(b, Count, 4<<20) }
-func BenchmarkCount64M(b *testing.B) { bmCount(b, Count, 64<<20) }
-
-func bmCount(b *testing.B, count func([]byte, []byte) int, n int) {
-	if len(bmbuf) < n {
-		bmbuf = make([]byte, n)
-	}
-	b.SetBytes(int64(n))
-	buf := bmbuf[0:n]
-	buf[n-1] = 'x'
-	for i := 0; i < b.N; i++ {
-		j := count(buf, buf[n-7:])
-		if j != 1 {
-			b.Fatal("bad count", j)
+func BenchmarkEqual(b *testing.B) {
+	b.Run("0", func(b *testing.B) {
+		var buf [4]byte
+		buf1 := buf[0:0]
+		buf2 := buf[1:1]
+		for i := 0; i < b.N; i++ {
+			eq := Equal(buf1, buf2)
+			if !eq {
+				b.Fatal("bad equal")
+			}
 		}
-	}
-	buf[n-1] = '\x00'
+	})
+
+	sizes := []int{1, 6, 9, 15, 16, 20, 32, 4 << 10, 4 << 20, 64 << 20}
+	benchBytes(b, sizes, bmEqual(Equal))
 }
 
-func BenchmarkCountEasy32(b *testing.B)  { bmCountEasy(b, Count, 32) }
-func BenchmarkCountEasy4K(b *testing.B)  { bmCountEasy(b, Count, 4<<10) }
-func BenchmarkCountEasy4M(b *testing.B)  { bmCountEasy(b, Count, 4<<20) }
-func BenchmarkCountEasy64M(b *testing.B) { bmCountEasy(b, Count, 64<<20) }
+func BenchmarkEqualPort(b *testing.B) {
+	sizes := []int{1, 6, 32, 4 << 10, 4 << 20, 64 << 20}
+	benchBytes(b, sizes, bmEqual(EqualPortable))
+}
 
-func bmCountEasy(b *testing.B, count func([]byte, []byte) int, n int) {
-	if len(bmbuf) < n {
-		bmbuf = make([]byte, n)
-	}
-	b.SetBytes(int64(n))
-	buf := bmbuf[0:n]
-	buf[n-1] = 'x'
-	buf[n-7] = 'x'
-	for i := 0; i < b.N; i++ {
-		j := count(buf, buf[n-7:])
-		if j != 1 {
-			b.Fatal("bad count", j)
+func bmEqual(equal func([]byte, []byte) bool) func(b *testing.B, n int) {
+	return func(b *testing.B, n int) {
+		if len(bmbuf) < 2*n {
+			bmbuf = make([]byte, 2*n)
+		}
+		buf1 := bmbuf[0:n]
+		buf2 := bmbuf[n : 2*n]
+		buf1[n-1] = 'x'
+		buf2[n-1] = 'x'
+		for i := 0; i < b.N; i++ {
+			eq := equal(buf1, buf2)
+			if !eq {
+				b.Fatal("bad equal")
+			}
 		}
+		buf1[n-1] = '\x00'
+		buf2[n-1] = '\x00'
 	}
-	buf[n-1] = '\x00'
-	buf[n-7] = '\x00'
+}
+
+func BenchmarkIndex(b *testing.B) {
+	benchBytes(b, indexSizes, func(b *testing.B, n int) {
+		buf := bmbuf[0:n]
+		buf[n-1] = 'x'
+		for i := 0; i < b.N; i++ {
+			j := Index(buf, buf[n-7:])
+			if j != n-7 {
+				b.Fatal("bad index", j)
+			}
+		}
+		buf[n-1] = '\x00'
+	})
+}
+
+func BenchmarkIndexEasy(b *testing.B) {
+	benchBytes(b, indexSizes, func(b *testing.B, n int) {
+		buf := bmbuf[0:n]
+		buf[n-1] = 'x'
+		buf[n-7] = 'x'
+		for i := 0; i < b.N; i++ {
+			j := Index(buf, buf[n-7:])
+			if j != n-7 {
+				b.Fatal("bad index", j)
+			}
+		}
+		buf[n-1] = '\x00'
+		buf[n-7] = '\x00'
+	})
+}
+
+func BenchmarkCount(b *testing.B) {
+	benchBytes(b, indexSizes, func(b *testing.B, n int) {
+		buf := bmbuf[0:n]
+		buf[n-1] = 'x'
+		for i := 0; i < b.N; i++ {
+			j := Count(buf, buf[n-7:])
+			if j != 1 {
+				b.Fatal("bad count", j)
+			}
+		}
+		buf[n-1] = '\x00'
+	})
+}
+
+func BenchmarkCountEasy(b *testing.B) {
+	benchBytes(b, indexSizes, func(b *testing.B, n int) {
+		buf := bmbuf[0:n]
+		buf[n-1] = 'x'
+		buf[n-7] = 'x'
+		for i := 0; i < b.N; i++ {
+			j := Count(buf, buf[n-7:])
+			if j != 1 {
+				b.Fatal("bad count", j)
+			}
+		}
+		buf[n-1] = '\x00'
+		buf[n-7] = '\x00'
+	})
 }
 
 type ExplodeTest struct {
@@ -760,7 +757,7 @@ func TestMap(t *testing.T) {
 	// Run a couple of awful growth/shrinkage tests
 	a := tenRunes('a')
 
-	// 1.  Grow.  This triggers two reallocations in Map.
+	// 1.  Grow. This triggers two reallocations in Map.
 	maxRune := func(r rune) rune { return unicode.MaxRune }
 	m := Map(maxRune, []byte(a))
 	expect := tenRunes(unicode.MaxRune)
@@ -1207,6 +1204,57 @@ func TestContains(t *testing.T) {
 	}
 }
 
+var ContainsAnyTests = []struct {
+	b        []byte
+	substr   string
+	expected bool
+}{
+	{[]byte(""), "", false},
+	{[]byte(""), "a", false},
+	{[]byte(""), "abc", false},
+	{[]byte("a"), "", false},
+	{[]byte("a"), "a", true},
+	{[]byte("aaa"), "a", true},
+	{[]byte("abc"), "xyz", false},
+	{[]byte("abc"), "xcz", true},
+	{[]byte("a☺b☻c☹d"), "uvw☻xyz", true},
+	{[]byte("aRegExp*"), ".(|)*+?^$[]", true},
+	{[]byte(dots + dots + dots), " ", false},
+}
+
+func TestContainsAny(t *testing.T) {
+	for _, ct := range ContainsAnyTests {
+		if ContainsAny(ct.b, ct.substr) != ct.expected {
+			t.Errorf("ContainsAny(%s, %s) = %v, want %v",
+				ct.b, ct.substr, !ct.expected, ct.expected)
+		}
+	}
+}
+
+var ContainsRuneTests = []struct {
+	b        []byte
+	r        rune
+	expected bool
+}{
+	{[]byte(""), 'a', false},
+	{[]byte("a"), 'a', true},
+	{[]byte("aaa"), 'a', true},
+	{[]byte("abc"), 'y', false},
+	{[]byte("abc"), 'c', true},
+	{[]byte("a☺b☻c☹d"), 'x', false},
+	{[]byte("a☺b☻c☹d"), '☻', true},
+	{[]byte("aRegExp*"), '*', true},
+}
+
+func TestContainsRune(t *testing.T) {
+	for _, ct := range ContainsRuneTests {
+		if ContainsRune(ct.b, ct.r) != ct.expected {
+			t.Errorf("ContainsRune(%q, %q) = %v, want %v",
+				ct.b, ct.r, !ct.expected, ct.expected)
+		}
+	}
+}
+
 var makeFieldsInput = func() []byte {
 	x := make([]byte, 1<<20)
 	// Input is ~10% space, ~10% 2-byte UTF-8, rest ASCII non-space.
@@ -1256,33 +1304,24 @@ func BenchmarkRepeat(b *testing.B) {
 	}
 }
 
-func benchmarkBytesCompare(b *testing.B, n int) {
-	var x = make([]byte, n)
-	var y = make([]byte, n)
+func BenchmarkBytesCompare(b *testing.B) {
+	for n := 1; n <= 2048; n <<= 1 {
+		b.Run(fmt.Sprint(n), func(b *testing.B) {
+			var x = make([]byte, n)
+			var y = make([]byte, n)
 
-	for i := 0; i < n; i++ {
-		x[i] = 'a'
-	}
+			for i := 0; i < n; i++ {
+				x[i] = 'a'
+			}
 
-	for i := 0; i < n; i++ {
-		y[i] = 'a'
-	}
+			for i := 0; i < n; i++ {
+				y[i] = 'a'
+			}
 
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		Compare(x, y)
-	}
-}
-
-func BenchmarkBytesCompare1(b *testing.B)    { benchmarkBytesCompare(b, 1) }
-func BenchmarkBytesCompare2(b *testing.B)    { benchmarkBytesCompare(b, 2) }
-func BenchmarkBytesCompare4(b *testing.B)    { benchmarkBytesCompare(b, 4) }
-func BenchmarkBytesCompare8(b *testing.B)    { benchmarkBytesCompare(b, 8) }
-func BenchmarkBytesCompare16(b *testing.B)   { benchmarkBytesCompare(b, 16) }
-func BenchmarkBytesCompare32(b *testing.B)   { benchmarkBytesCompare(b, 32) }
-func BenchmarkBytesCompare64(b *testing.B)   { benchmarkBytesCompare(b, 64) }
-func BenchmarkBytesCompare128(b *testing.B)  { benchmarkBytesCompare(b, 128) }
-func BenchmarkBytesCompare256(b *testing.B)  { benchmarkBytesCompare(b, 256) }
-func BenchmarkBytesCompare512(b *testing.B)  { benchmarkBytesCompare(b, 512) }
-func BenchmarkBytesCompare1024(b *testing.B) { benchmarkBytesCompare(b, 1024) }
-func BenchmarkBytesCompare2048(b *testing.B) { benchmarkBytesCompare(b, 2048) }
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				Compare(x, y)
+			}
+		})
+	}
+}
diff --git a/libgo/go/bytes/compare_test.go b/libgo/go/bytes/compare_test.go
index f2d81d5310c..35088a1b2e9 100644
--- a/libgo/go/bytes/compare_test.go
+++ b/libgo/go/bytes/compare_test.go
@@ -62,7 +62,7 @@ func TestCompareBytes(t *testing.T) {
 	a := make([]byte, n+1)
 	b := make([]byte, n+1)
 	for len := 0; len < 128; len++ {
-		// randomish but deterministic data.  No 0 or 255.
+		// randomish but deterministic data. No 0 or 255.
 		for i := 0; i < len; i++ {
 			a[i] = byte(1 + 31*i%254)
 			b[i] = byte(1 + 31*i%254)
diff --git a/libgo/go/bytes/equal_test.go b/libgo/go/bytes/equal_test.go
index 1bf19a74b80..9fdead8a604 100644
--- a/libgo/go/bytes/equal_test.go
+++ b/libgo/go/bytes/equal_test.go
@@ -14,11 +14,11 @@ import (
 )
 
 // This file tests the situation where memeq is checking
-// data very near to a page boundary.  We want to make sure
+// data very near to a page boundary. We want to make sure
 // equal does not read across the boundary and cause a page
 // fault where it shouldn't.
 
-// This test runs only on linux.  The code being tested is
+// This test runs only on linux. The code being tested is
 // not OS-specific, so it does not need to be tested on all
 // operating systems.
 
diff --git a/libgo/go/bytes/reader.go b/libgo/go/bytes/reader.go
index b89d1548f1b..28cfc7a9788 100644
--- a/libgo/go/bytes/reader.go
+++ b/libgo/go/bytes/reader.go
@@ -36,9 +36,6 @@ func (r *Reader) Len() int {
 func (r *Reader) Size() int64 { return int64(len(r.s)) }
 
 func (r *Reader) Read(b []byte) (n int, err error) {
-	if len(b) == 0 {
-		return 0, nil
-	}
 	if r.i >= int64(len(r.s)) {
 		return 0, io.EOF
 	}
@@ -63,14 +60,14 @@ func (r *Reader) ReadAt(b []byte, off int64) (n int, err error) {
 	return
 }
 
-func (r *Reader) ReadByte() (b byte, err error) {
+func (r *Reader) ReadByte() (byte, error) {
 	r.prevRune = -1
 	if r.i >= int64(len(r.s)) {
 		return 0, io.EOF
 	}
-	b = r.s[r.i]
+	b := r.s[r.i]
 	r.i++
-	return
+	return b, nil
 }
 
 func (r *Reader) UnreadByte() error {
@@ -111,11 +108,11 @@ func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 	r.prevRune = -1
 	var abs int64
 	switch whence {
-	case 0:
+	case io.SeekStart:
 		abs = offset
-	case 1:
-		abs = int64(r.i) + offset
-	case 2:
+	case io.SeekCurrent:
+		abs = r.i + offset
+	case io.SeekEnd:
 		abs = int64(len(r.s)) + offset
 	default:
 		return 0, errors.New("bytes.Reader.Seek: invalid whence")
@@ -146,5 +143,8 @@ func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	return
 }
 
+// Reset resets the Reader to be reading from b.
+func (r *Reader) Reset(b []byte) { *r = Reader{b, 0, -1} }
+
 // NewReader returns a new Reader reading from b.
 func NewReader(b []byte) *Reader { return &Reader{b, 0, -1} }
diff --git a/libgo/go/bytes/reader_test.go b/libgo/go/bytes/reader_test.go
index b929a282609..7b3034d4e0d 100644
--- a/libgo/go/bytes/reader_test.go
+++ b/libgo/go/bytes/reader_test.go
@@ -9,7 +9,6 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"os"
 	"sync"
 	"testing"
 )
@@ -22,17 +21,18 @@ func TestReader(t *testing.T) {
 		n       int
 		want    string
 		wantpos int64
+		readerr error
 		seekerr string
 	}{
-		{seek: os.SEEK_SET, off: 0, n: 20, want: "0123456789"},
-		{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
-		{seek: os.SEEK_SET, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
-		{seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
-		{seek: os.SEEK_SET, n: 5, want: "01234"},
-		{seek: os.SEEK_CUR, n: 5, want: "56789"},
-		{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
+		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
+		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
+		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
+		{seek: io.SeekStart, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
+		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},
+		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1, readerr: io.EOF},
+		{seek: io.SeekStart, n: 5, want: "01234"},
+		{seek: io.SeekCurrent, n: 5, want: "56789"},
+		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
 	}
 
 	for i, tt := range tests {
@@ -50,8 +50,8 @@ func TestReader(t *testing.T) {
 		}
 		buf := make([]byte, tt.n)
 		n, err := r.Read(buf)
-		if err != nil {
-			t.Errorf("%d. read = %v", i, err)
+		if err != tt.readerr {
+			t.Errorf("%d. read = %v; want %v", i, err, tt.readerr)
 			continue
 		}
 		got := string(buf[:n])
@@ -63,7 +63,7 @@ func TestReader(t *testing.T) {
 
 func TestReadAfterBigSeek(t *testing.T) {
 	r := NewReader([]byte("0123456789"))
-	if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+	if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
 		t.Fatal(err)
 	}
 	if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
@@ -174,7 +174,7 @@ func TestReaderLen(t *testing.T) {
 		t.Errorf("r.Len(): got %d, want %d", got, want)
 	}
 	if n, err := r.Read(make([]byte, 1)); err != nil || n != 1 {
-		t.Errorf("Read failed: read %d %v", n, err)
+		t.Errorf("Read failed: read %d %v; want 1, nil", n, err)
 	}
 	if got, want := r.Len(), 0; got != want {
 		t.Errorf("r.Len(): got %d, want %d", got, want)
@@ -188,7 +188,7 @@ var UnreadRuneErrorTests = []struct {
 	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
 	{"ReadByte", func(r *Reader) { r.ReadByte() }},
 	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
-	{"Seek", func(r *Reader) { r.Seek(0, 1) }},
+	{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
 	{"WriteTo", func(r *Reader) { r.WriteTo(&Buffer{}) }},
 }
 
@@ -256,3 +256,23 @@ func TestReaderLenSize(t *testing.T) {
 		t.Errorf("Size = %d; want 3", r.Size())
 	}
 }
+
+func TestReaderReset(t *testing.T) {
+	r := NewReader([]byte("世界"))
+	if _, _, err := r.ReadRune(); err != nil {
+		t.Errorf("ReadRune: unexpected error: %v", err)
+	}
+
+	const want = "abcdef"
+	r.Reset([]byte(want))
+	if err := r.UnreadRune(); err == nil {
+		t.Errorf("UnreadRune: expected error, got nil")
+	}
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Errorf("ReadAll: unexpected error: %v", err)
+	}
+	if got := string(buf); got != want {
+		t.Errorf("ReadAll: got %q, want %q", got, want)
+	}
+}
diff --git a/libgo/go/cmd/cgo/ast.go b/libgo/go/cmd/cgo/ast.go
index c3a24c2b763..000ecd44685 100644
--- a/libgo/go/cmd/cgo/ast.go
+++ b/libgo/go/cmd/cgo/ast.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -40,7 +40,7 @@ func sourceLine(n ast.Node) int {
 }
 
 // ReadGo populates f with information learned from reading the
-// Go source file with the given file name.  It gathers the C preamble
+// Go source file with the given file name. It gathers the C preamble
 // attached to the import "C" comment, a list of references to C.xxx,
 // a list of exported functions, and the actual AST, to be rewritten and
 // printed.
@@ -73,7 +73,7 @@ func (f *File) ReadGo(name string) {
 		}
 		for _, spec := range d.Specs {
 			s, ok := spec.(*ast.ImportSpec)
-			if !ok || string(s.Path.Value) != `"C"` {
+			if !ok || s.Path.Value != `"C"` {
 				continue
 			}
 			sawC = true
@@ -106,7 +106,7 @@ func (f *File) ReadGo(name string) {
 		ws := 0
 		for _, spec := range d.Specs {
 			s, ok := spec.(*ast.ImportSpec)
-			if !ok || string(s.Path.Value) != `"C"` {
+			if !ok || s.Path.Value != `"C"` {
 				d.Specs[ws] = spec
 				ws++
 			}
@@ -147,7 +147,7 @@ func commentText(g *ast.CommentGroup) string {
 	}
 	var pieces []string
 	for _, com := range g.List {
-		c := string(com.Text)
+		c := com.Text
 		// Remove comment markers.
 		// The parser has given us exactly the comment text.
 		switch c[1] {
@@ -172,7 +172,7 @@ func (f *File) saveExprs(x interface{}, context string) {
 			f.saveRef(x, context)
 		}
 	case *ast.CallExpr:
-		f.saveCall(x)
+		f.saveCall(x, context)
 	}
 }
 
@@ -220,7 +220,7 @@ func (f *File) saveRef(n *ast.Expr, context string) {
 }
 
 // Save calls to C.xxx for later processing.
-func (f *File) saveCall(call *ast.CallExpr) {
+func (f *File) saveCall(call *ast.CallExpr, context string) {
 	sel, ok := call.Fun.(*ast.SelectorExpr)
 	if !ok {
 		return
@@ -228,7 +228,8 @@ func (f *File) saveCall(call *ast.CallExpr) {
 	if l, ok := sel.X.(*ast.Ident); !ok || l.Name != "C" {
 		return
 	}
-	f.Calls = append(f.Calls, call)
+	c := &Call{Call: call, Deferred: context == "defer"}
+	f.Calls = append(f.Calls, c)
 }
 
 // If a function should be exported add it to ExpFunc.
@@ -242,11 +243,11 @@ func (f *File) saveExport(x interface{}, context string) {
 		return
 	}
 	for _, c := range n.Doc.List {
-		if !strings.HasPrefix(string(c.Text), "//export ") {
+		if !strings.HasPrefix(c.Text, "//export ") {
 			continue
 		}
 
-		name := strings.TrimSpace(string(c.Text[9:]))
+		name := strings.TrimSpace(c.Text[9:])
 		if name == "" {
 			error_(c.Pos(), "export missing name")
 		}
@@ -401,7 +402,7 @@ func (f *File) walk(x interface{}, context string, visit func(*File, interface{}
 	case *ast.GoStmt:
 		f.walk(n.Call, "expr", visit)
 	case *ast.DeferStmt:
-		f.walk(n.Call, "expr", visit)
+		f.walk(n.Call, "defer", visit)
 	case *ast.ReturnStmt:
 		f.walk(n.Results, "expr", visit)
 	case *ast.BranchStmt:
@@ -447,7 +448,11 @@ func (f *File) walk(x interface{}, context string, visit func(*File, interface{}
 	case *ast.ImportSpec:
 	case *ast.ValueSpec:
 		f.walk(&n.Type, "type", visit)
-		f.walk(n.Values, "expr", visit)
+		if len(n.Names) == 2 && len(n.Values) == 1 {
+			f.walk(&n.Values[0], "as2", visit)
+		} else {
+			f.walk(n.Values, "expr", visit)
+		}
 	case *ast.TypeSpec:
 		f.walk(&n.Type, "type", visit)
 
diff --git a/libgo/go/cmd/cgo/doc.go b/libgo/go/cmd/cgo/doc.go
index bd38a5c153b..d3a7b6d2a73 100644
--- a/libgo/go/cmd/cgo/doc.go
+++ b/libgo/go/cmd/cgo/doc.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -31,9 +31,9 @@ See $GOROOT/misc/cgo/stdio and $GOROOT/misc/cgo/gmp for examples.  See
 "C? Go? Cgo!" for an introduction to using cgo:
 https://golang.org/doc/articles/c_go_cgo.html.
 
-CFLAGS, CPPFLAGS, CXXFLAGS and LDFLAGS may be defined with pseudo #cgo
-directives within these comments to tweak the behavior of the C or C++
-compiler.  Values defined in multiple directives are concatenated
+CFLAGS, CPPFLAGS, CXXFLAGS, FFLAGS and LDFLAGS may be defined with pseudo
+#cgo directives within these comments to tweak the behavior of the C, C++
+or Fortran compiler.  Values defined in multiple directives are concatenated
 together.  The directive can include a list of build constraints limiting its
 effect to systems satisfying one of the constraints
 (see https://golang.org/pkg/go/build/#hdr-Build_Constraints for details about the constraint syntax).
@@ -53,7 +53,7 @@ For example:
 	// #include <png.h>
 	import "C"
 
-When building, the CGO_CFLAGS, CGO_CPPFLAGS, CGO_CXXFLAGS and
+When building, the CGO_CFLAGS, CGO_CPPFLAGS, CGO_CXXFLAGS, CGO_FFLAGS and
 CGO_LDFLAGS environment variables are added to the flags derived from
 these directives.  Package-specific flags should be set using the
 directives, not the environment variables, so that builds work in
@@ -62,10 +62,11 @@ unmodified environments.
 All the cgo CPPFLAGS and CFLAGS directives in a package are concatenated and
 used to compile C files in that package.  All the CPPFLAGS and CXXFLAGS
 directives in a package are concatenated and used to compile C++ files in that
-package.  All the LDFLAGS directives in any package in the program are
-concatenated and used at link time.  All the pkg-config directives are
-concatenated and sent to pkg-config simultaneously to add to each appropriate
-set of command-line flags.
+package.  All the CPPFLAGS and FFLAGS directives in a package are concatenated
+and used to compile Fortran files in that package.  All the LDFLAGS directives
+in any package in the program are concatenated and used at link time.  All the
+pkg-config directives are concatenated and sent to pkg-config simultaneously
+to add to each appropriate set of command-line flags.
 
 When the cgo directives are parsed, any occurrence of the string ${SRCDIR}
 will be replaced by the absolute path to the directory containing the source
@@ -83,7 +84,8 @@ When the Go tool sees that one or more Go files use the special import
 "C", it will look for other non-Go files in the directory and compile
 them as part of the Go package.  Any .c, .s, or .S files will be
 compiled with the C compiler.  Any .cc, .cpp, or .cxx files will be
-compiled with the C++ compiler.  Any .h, .hh, .hpp, or .hxx files will
+compiled with the C++ compiler.  Any .f, .F, .for or .f90 files will be
+compiled with the fortran compiler. Any .h, .hh, .hpp, or .hxx files will
 not be compiled separately, but, if these header files are changed,
 the C and C++ files will be recompiled.  The default C and C++
 compilers may be changed by the CC and CXX environment variables,
@@ -133,7 +135,7 @@ C's union types are represented as a Go byte array with the same length.
 
 Go structs cannot embed fields with C types.
 
-Go code can not refer to zero-sized fields that occur at the end of
+Go code cannot refer to zero-sized fields that occur at the end of
 non-empty C structs.  To get the address of such a field (which is the
 only operation you can do with a zero-sized field) you must take the
 address of the struct and add the size of the struct.
@@ -148,8 +150,9 @@ assignment context to retrieve both the return value (if any) and the
 C errno variable as an error (use _ to skip the result value if the
 function returns void).  For example:
 
-	n, err := C.sqrt(-1)
+	n, err = C.sqrt(-1)
 	_, err := C.voidFunc()
+	var n, err = C.sqrt(1)
 
 Calling C function pointers is currently not supported, however you can
 declare Go variables which hold C function pointers and pass them
@@ -195,6 +198,13 @@ by making copies of the data.  In pseudo-Go definitions:
 	// if C.free is needed).
 	func C.CString(string) *C.char
 
+	// Go []byte slice to C array
+	// The C array is allocated in the C heap using malloc.
+	// It is the caller's responsibility to arrange for it to be
+	// freed, such as by calling C.free (be sure to include stdlib.h
+	// if C.free is needed).
+	func C.CBytes([]byte) unsafe.Pointer
+
 	// C string to Go string
 	func C.GoString(*C.char) string
 
@@ -501,7 +511,6 @@ file compiled by gcc, the file x.cgo2.c:
 	void
 	_cgo_be59f0f25121_Cfunc_puts(void *v)
 	{
-		_cgo_wait_runtime_init_done();
 		struct {
 			char* p0;
 			int r;
@@ -510,8 +519,7 @@ file compiled by gcc, the file x.cgo2.c:
 		a->r = puts((void*)a->p0);
 	}
 
-It waits for Go runtime to be initialized (required for shared libraries),
-extracts the arguments from the pointer to _Cfunc_puts's argument
+It extracts the arguments from the pointer to _Cfunc_puts's argument
 frame, invokes the system C function (in this case, puts), stores the
 result in the frame, and returns.
 
@@ -529,8 +537,8 @@ linkage to the desired libraries. The main function is provided by
 _cgo_main.c:
 
 	int main() { return 0; }
-	void crosscall2(void(*fn)(void*, int), void *a, int c) { }
-	void _cgo_wait_runtime_init_done() { }
+	void crosscall2(void(*fn)(void*, int, uintptr_t), void *a, int c, uintptr_t ctxt) { }
+	uintptr_t _cgo_wait_runtime_init_done() { }
 	void _cgo_allocate(void *a, int c) { }
 	void _cgo_panic(void *a, int c) { }
 
diff --git a/libgo/go/cmd/cgo/gcc.go b/libgo/go/cmd/cgo/gcc.go
index fb5049c1a1d..fc1d01100d2 100644
--- a/libgo/go/cmd/cgo/gcc.go
+++ b/libgo/go/cmd/cgo/gcc.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -83,7 +83,7 @@ func (f *File) DiscardCgoDirectives() {
 	f.Preamble = strings.Join(linesOut, "\n")
 }
 
-// addToFlag appends args to flag.  All flags are later written out onto the
+// addToFlag appends args to flag. All flags are later written out onto the
 // _cgo_flags file for the build system to use.
 func (p *Package) addToFlag(flag string, args []string) {
 	p.CgoFlags[flag] = append(p.CgoFlags[flag], args...)
@@ -99,7 +99,7 @@ func (p *Package) addToFlag(flag string, args []string) {
 // Single quotes and double quotes are recognized to prevent splitting within the
 // quoted region, and are removed from the resulting substrings. If a quote in s
 // isn't closed err will be set and r will have the unclosed argument as the
-// last element.  The backslash is used for escaping.
+// last element. The backslash is used for escaping.
 //
 // For example, the following string:
 //
@@ -236,7 +236,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 			if isConst {
 				n.Kind = "const"
 				// Turn decimal into hex, just for consistency
-				// with enum-derived constants.  Otherwise
+				// with enum-derived constants. Otherwise
 				// in the cgo -godefs output half the constants
 				// are in hex and half are in whatever the #define used.
 				i, err := strconv.ParseInt(n.Define, 0, 64)
@@ -385,7 +385,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 	if nerrors > 0 {
 		// Check if compiling the preamble by itself causes any errors,
 		// because the messages we've printed out so far aren't helpful
-		// to users debugging preamble mistakes.  See issue 8442.
+		// to users debugging preamble mistakes. See issue 8442.
 		preambleErrors := p.gccErrors([]byte(f.Preamble))
 		if len(preambleErrors) > 0 {
 			error_(token.NoPos, "\n%s errors for preamble:\n%s", p.gccBaseCmd()[0], preambleErrors)
@@ -403,7 +403,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 // being referred to as C.xxx.
 func (p *Package) loadDWARF(f *File, names []*Name) {
 	// Extract the types from the DWARF section of an object
-	// from a well-formed C program.  Gcc only generates DWARF info
+	// from a well-formed C program. Gcc only generates DWARF info
 	// for symbols in the object file, so it is not enough to print the
 	// preamble and hope the symbols we care about will be there.
 	// Instead, emit
@@ -421,7 +421,7 @@ func (p *Package) loadDWARF(f *File, names []*Name) {
 	}
 
 	// Apple's LLVM-based gcc does not include the enumeration
-	// names and values in its DWARF debug output.  In case we're
+	// names and values in its DWARF debug output. In case we're
 	// using such a gcc, create a data block initialized with the values.
 	// We can read them out of the object file.
 	fmt.Fprintf(&b, "long long __cgodebug_data[] = {\n")
@@ -432,7 +432,7 @@ func (p *Package) loadDWARF(f *File, names []*Name) {
 			fmt.Fprintf(&b, "\t0,\n")
 		}
 	}
-	// for the last entry, we can not use 0, otherwise
+	// for the last entry, we cannot use 0, otherwise
 	// in case all __cgodebug_data is zero initialized,
 	// LLVM-based gcc will place the it in the __DATA.__common
 	// zero-filled section (our debug/macho doesn't support
@@ -581,7 +581,7 @@ func (p *Package) mangleName(n *Name) {
 func (p *Package) rewriteCalls(f *File) {
 	for _, call := range f.Calls {
 		// This is a call to C.xxx; set goname to "xxx".
-		goname := call.Fun.(*ast.SelectorExpr).Sel.Name
+		goname := call.Call.Fun.(*ast.SelectorExpr).Sel.Name
 		if goname == "malloc" {
 			continue
 		}
@@ -594,39 +594,62 @@ func (p *Package) rewriteCalls(f *File) {
 	}
 }
 
-// rewriteCall rewrites one call to add pointer checks.  We replace
+// rewriteCall rewrites one call to add pointer checks. We replace
 // each pointer argument x with _cgoCheckPointer(x).(T).
-func (p *Package) rewriteCall(f *File, call *ast.CallExpr, name *Name) {
+func (p *Package) rewriteCall(f *File, call *Call, name *Name) {
+	// Avoid a crash if the number of arguments is
+	// less than the number of parameters.
+	// This will be caught when the generated file is compiled.
+	if len(call.Call.Args) < len(name.FuncType.Params) {
+		return
+	}
+
+	any := false
 	for i, param := range name.FuncType.Params {
-		if len(call.Args) <= i {
-			// Avoid a crash; this will be caught when the
-			// generated file is compiled.
-			return
-		}
-
-		// An untyped nil does not need a pointer check, and
-		// when _cgoCheckPointer returns the untyped nil the
-		// type assertion we are going to insert will fail.
-		// Easier to just skip nil arguments.
-		// TODO: Note that this fails if nil is shadowed.
-		if id, ok := call.Args[i].(*ast.Ident); ok && id.Name == "nil" {
-			continue
+		if p.needsPointerCheck(f, param.Go, call.Call.Args[i]) {
+			any = true
+			break
+		}
+	}
+	if !any {
+		return
+	}
+
+	// We need to rewrite this call.
+	//
+	// We are going to rewrite C.f(p) to C.f(_cgoCheckPointer(p)).
+	// If the call to C.f is deferred, that will check p at the
+	// point of the defer statement, not when the function is called, so
+	// rewrite to func(_cgo0 ptype) { C.f(_cgoCheckPointer(_cgo0)) }(p)
+
+	var dargs []ast.Expr
+	if call.Deferred {
+		dargs = make([]ast.Expr, len(name.FuncType.Params))
+	}
+	for i, param := range name.FuncType.Params {
+		origArg := call.Call.Args[i]
+		darg := origArg
+
+		if call.Deferred {
+			dargs[i] = darg
+			darg = ast.NewIdent(fmt.Sprintf("_cgo%d", i))
+			call.Call.Args[i] = darg
 		}
 
-		if !p.needsPointerCheck(f, param.Go) {
+		if !p.needsPointerCheck(f, param.Go, origArg) {
 			continue
 		}
 
 		c := &ast.CallExpr{
 			Fun: ast.NewIdent("_cgoCheckPointer"),
 			Args: []ast.Expr{
-				call.Args[i],
+				darg,
 			},
 		}
 
 		// Add optional additional arguments for an address
 		// expression.
-		c.Args = p.checkAddrArgs(f, c.Args, call.Args[i])
+		c.Args = p.checkAddrArgs(f, c.Args, origArg)
 
 		// _cgoCheckPointer returns interface{}.
 		// We need to type assert that to the type we want.
@@ -636,19 +659,19 @@ func (p *Package) rewriteCall(f *File, call *ast.CallExpr, name *Name) {
 		// Instead we use a local variant of _cgoCheckPointer.
 
 		var arg ast.Expr
-		if n := p.unsafeCheckPointerName(param.Go); n != "" {
+		if n := p.unsafeCheckPointerName(param.Go, call.Deferred); n != "" {
 			c.Fun = ast.NewIdent(n)
 			arg = c
 		} else {
 			// In order for the type assertion to succeed,
 			// we need it to match the actual type of the
-			// argument.  The only type we have is the
-			// type of the function parameter.  We know
+			// argument. The only type we have is the
+			// type of the function parameter. We know
 			// that the argument type must be assignable
 			// to the function parameter type, or the code
 			// would not compile, but there is nothing
 			// requiring that the types be exactly the
-			// same.  Add a type conversion to the
+			// same. Add a type conversion to the
 			// argument so that the type assertion will
 			// succeed.
 			c.Args[0] = &ast.CallExpr{
@@ -664,18 +687,77 @@ func (p *Package) rewriteCall(f *File, call *ast.CallExpr, name *Name) {
 			}
 		}
 
-		call.Args[i] = arg
+		call.Call.Args[i] = arg
+	}
+
+	if call.Deferred {
+		params := make([]*ast.Field, len(name.FuncType.Params))
+		for i, param := range name.FuncType.Params {
+			ptype := param.Go
+			if p.hasUnsafePointer(ptype) {
+				// Avoid generating unsafe.Pointer by using
+				// interface{}. This works because we are
+				// going to call a _cgoCheckPointer function
+				// anyhow.
+				ptype = &ast.InterfaceType{
+					Methods: &ast.FieldList{},
+				}
+			}
+			params[i] = &ast.Field{
+				Names: []*ast.Ident{
+					ast.NewIdent(fmt.Sprintf("_cgo%d", i)),
+				},
+				Type: ptype,
+			}
+		}
+
+		dbody := &ast.CallExpr{
+			Fun:  call.Call.Fun,
+			Args: call.Call.Args,
+		}
+		call.Call.Fun = &ast.FuncLit{
+			Type: &ast.FuncType{
+				Params: &ast.FieldList{
+					List: params,
+				},
+			},
+			Body: &ast.BlockStmt{
+				List: []ast.Stmt{
+					&ast.ExprStmt{
+						X: dbody,
+					},
+				},
+			},
+		}
+		call.Call.Args = dargs
+		call.Call.Lparen = token.NoPos
+		call.Call.Rparen = token.NoPos
+
+		// There is a Ref pointing to the old call.Call.Fun.
+		for _, ref := range f.Ref {
+			if ref.Expr == &call.Call.Fun {
+				ref.Expr = &dbody.Fun
+			}
+		}
 	}
 }
 
 // needsPointerCheck returns whether the type t needs a pointer check.
 // This is true if t is a pointer and if the value to which it points
 // might contain a pointer.
-func (p *Package) needsPointerCheck(f *File, t ast.Expr) bool {
+func (p *Package) needsPointerCheck(f *File, t ast.Expr, arg ast.Expr) bool {
+	// An untyped nil does not need a pointer check, and when
+	// _cgoCheckPointer returns the untyped nil the type assertion we
+	// are going to insert will fail.  Easier to just skip nil arguments.
+	// TODO: Note that this fails if nil is shadowed.
+	if id, ok := arg.(*ast.Ident); ok && id.Name == "nil" {
+		return false
+	}
+
 	return p.hasPointer(f, t, true)
 }
 
-// hasPointer is used by needsPointerCheck.  If top is true it returns
+// hasPointer is used by needsPointerCheck. If top is true it returns
 // whether t is or contains a pointer that might point to a pointer.
 // If top is false it returns whether t is or contains a pointer.
 // f may be nil.
@@ -732,7 +814,7 @@ func (p *Package) hasPointer(f *File, t ast.Expr, top bool) bool {
 		if goTypes[t.Name] != nil {
 			return false
 		}
-		// We can't figure out the type.  Conservative
+		// We can't figure out the type. Conservative
 		// approach is to assume it has a pointer.
 		return true
 	case *ast.SelectorExpr:
@@ -750,7 +832,7 @@ func (p *Package) hasPointer(f *File, t ast.Expr, top bool) bool {
 		if name != nil && name.Kind == "type" && name.Type != nil && name.Type.Go != nil {
 			return p.hasPointer(f, name.Type.Go, top)
 		}
-		// We can't figure out the type.  Conservative
+		// We can't figure out the type. Conservative
 		// approach is to assume it has a pointer.
 		return true
 	default:
@@ -760,14 +842,14 @@ func (p *Package) hasPointer(f *File, t ast.Expr, top bool) bool {
 }
 
 // checkAddrArgs tries to add arguments to the call of
-// _cgoCheckPointer when the argument is an address expression.  We
+// _cgoCheckPointer when the argument is an address expression. We
 // pass true to mean that the argument is an address operation of
 // something other than a slice index, which means that it's only
 // necessary to check the specific element pointed to, not the entire
-// object.  This is for &s.f, where f is a field in a struct.  We can
+// object. This is for &s.f, where f is a field in a struct. We can
 // pass a slice or array, meaning that we should check the entire
 // slice or array but need not check any other part of the object.
-// This is for &s.a[i], where we need to check all of a.  However, we
+// This is for &s.a[i], where we need to check all of a. However, we
 // only pass the slice or array if we can refer to it without side
 // effects.
 func (p *Package) checkAddrArgs(f *File, args []ast.Expr, x ast.Expr) []ast.Expr {
@@ -786,7 +868,7 @@ func (p *Package) checkAddrArgs(f *File, args []ast.Expr, x ast.Expr) []ast.Expr
 	index, ok := u.X.(*ast.IndexExpr)
 	if !ok {
 		// This is the address of something that is not an
-		// index expression.  We only need to examine the
+		// index expression. We only need to examine the
 		// single value to which it points.
 		// TODO: what if true is shadowed?
 		return append(args, ast.NewIdent("true"))
@@ -819,14 +901,17 @@ func (p *Package) hasSideEffects(f *File, x ast.Expr) bool {
 func (p *Package) isType(t ast.Expr) bool {
 	switch t := t.(type) {
 	case *ast.SelectorExpr:
-		if t.Sel.Name != "Pointer" {
-			return false
-		}
 		id, ok := t.X.(*ast.Ident)
 		if !ok {
 			return false
 		}
-		return id.Name == "unsafe"
+		if id.Name == "unsafe" && t.Sel.Name == "Pointer" {
+			return true
+		}
+		if id.Name == "C" && typedef["_Ctype_"+t.Sel.Name] != nil {
+			return true
+		}
+		return false
 	case *ast.Ident:
 		// TODO: This ignores shadowing.
 		switch t.Name {
@@ -850,26 +935,37 @@ func (p *Package) isType(t ast.Expr) bool {
 	return false
 }
 
-// unsafeCheckPointerName is given the Go version of a C type.  If the
+// unsafeCheckPointerName is given the Go version of a C type. If the
 // type uses unsafe.Pointer, we arrange to build a version of
-// _cgoCheckPointer that returns that type.  This avoids using a type
-// assertion to unsafe.Pointer in our copy of user code.  We return
+// _cgoCheckPointer that returns that type. This avoids using a type
+// assertion to unsafe.Pointer in our copy of user code. We return
 // the name of the _cgoCheckPointer function we are going to build, or
 // the empty string if the type does not use unsafe.Pointer.
-func (p *Package) unsafeCheckPointerName(t ast.Expr) string {
+//
+// The deferred parameter is true if this check is for the argument of
+// a deferred function. In that case we need to use an empty interface
+// as the argument type, because the deferred function we introduce in
+// rewriteCall will use an empty interface type, and we can't add a
+// type assertion. This is handled by keeping a separate list, and
+// writing out the lists separately in writeDefs.
+func (p *Package) unsafeCheckPointerName(t ast.Expr, deferred bool) string {
 	if !p.hasUnsafePointer(t) {
 		return ""
 	}
 	var buf bytes.Buffer
 	conf.Fprint(&buf, fset, t)
 	s := buf.String()
-	for i, t := range p.CgoChecks {
+	checks := &p.CgoChecks
+	if deferred {
+		checks = &p.DeferredCgoChecks
+	}
+	for i, t := range *checks {
 		if s == t {
-			return p.unsafeCheckPointerNameIndex(i)
+			return p.unsafeCheckPointerNameIndex(i, deferred)
 		}
 	}
-	p.CgoChecks = append(p.CgoChecks, s)
-	return p.unsafeCheckPointerNameIndex(len(p.CgoChecks) - 1)
+	*checks = append(*checks, s)
+	return p.unsafeCheckPointerNameIndex(len(*checks)-1, deferred)
 }
 
 // hasUnsafePointer returns whether the Go type t uses unsafe.Pointer.
@@ -897,13 +993,16 @@ func (p *Package) hasUnsafePointer(t ast.Expr) bool {
 
 // unsafeCheckPointerNameIndex returns the name to use for a
 // _cgoCheckPointer variant based on the index in the CgoChecks slice.
-func (p *Package) unsafeCheckPointerNameIndex(i int) string {
+func (p *Package) unsafeCheckPointerNameIndex(i int, deferred bool) string {
+	if deferred {
+		return fmt.Sprintf("_cgoCheckPointerInDefer%d", i)
+	}
 	return fmt.Sprintf("_cgoCheckPointer%d", i)
 }
 
 // rewriteRef rewrites all the C.xxx references in f.AST to refer to the
 // Go equivalents, now that we have figured out the meaning of all
-// the xxx.  In *godefs mode, rewriteRef replaces the names
+// the xxx. In *godefs mode, rewriteRef replaces the names
 // with full definitions instead of mangled names.
 func (p *Package) rewriteRef(f *File) {
 	// Keep a list of all the functions, to remove the ones
@@ -926,7 +1025,7 @@ func (p *Package) rewriteRef(f *File) {
 
 	// Now that we have all the name types filled in,
 	// scan through the Refs to identify the ones that
-	// are trying to do a ,err call.  Also check that
+	// are trying to do a ,err call. Also check that
 	// functions are only used in calls.
 	for _, r := range f.Ref {
 		if r.Name.Kind == "const" && r.Name.Const == "" {
@@ -984,7 +1083,7 @@ func (p *Package) rewriteRef(f *File) {
 					f.Name[fpName] = name
 				}
 				r.Name = name
-				// Rewrite into call to _Cgo_ptr to prevent assignments.  The _Cgo_ptr
+				// Rewrite into call to _Cgo_ptr to prevent assignments. The _Cgo_ptr
 				// function is defined in out.go and simply returns its argument. See
 				// issue 7757.
 				expr = &ast.CallExpr{
@@ -1006,7 +1105,7 @@ func (p *Package) rewriteRef(f *File) {
 			if r.Name.Kind == "var" {
 				expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}
 			} else {
-				error_(r.Pos(), "only C variables allowed in selector expression", fixGo(r.Name.Go))
+				error_(r.Pos(), "only C variables allowed in selector expression %s", fixGo(r.Name.Go))
 			}
 
 		case "type":
@@ -1086,6 +1185,8 @@ func (p *Package) gccMachine() []string {
 		return []string{"-m31"}
 	case "s390x":
 		return []string{"-m64"}
+	case "mips64", "mips64le":
+		return []string{"-mabi=64"}
 	}
 	return nil
 }
@@ -1152,7 +1253,7 @@ func (p *Package) gccDebug(stdin []byte) (*dwarf.Data, binary.ByteOrder, []byte)
 			for i := range f.Symtab.Syms {
 				s := &f.Symtab.Syms[i]
 				if isDebugData(s.Name) {
-					// Found it.  Now find data section.
+					// Found it. Now find data section.
 					if i := int(s.Sect) - 1; 0 <= i && i < len(f.Sections) {
 						sect := f.Sections[i]
 						if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
@@ -1179,7 +1280,7 @@ func (p *Package) gccDebug(stdin []byte) (*dwarf.Data, binary.ByteOrder, []byte)
 			for i := range symtab {
 				s := &symtab[i]
 				if isDebugData(s.Name) {
-					// Found it.  Now find data section.
+					// Found it. Now find data section.
 					if i := int(s.Section); 0 <= i && i < len(f.Sections) {
 						sect := f.Sections[i]
 						if sect.Addr <= s.Value && s.Value < sect.Addr+sect.Size {
@@ -1232,18 +1333,26 @@ func (p *Package) gccDefines(stdin []byte) string {
 }
 
 // gccErrors runs gcc over the C program stdin and returns
-// the errors that gcc prints.  That is, this function expects
+// the errors that gcc prints. That is, this function expects
 // gcc to fail.
 func (p *Package) gccErrors(stdin []byte) string {
 	// TODO(rsc): require failure
 	args := p.gccCmd()
 
+	// Optimization options can confuse the error messages; remove them.
+	nargs := make([]string, 0, len(args))
+	for _, arg := range args {
+		if !strings.HasPrefix(arg, "-O") {
+			nargs = append(nargs, arg)
+		}
+	}
+
 	if *debugGcc {
-		fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(args, " "))
+		fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(nargs, " "))
 		os.Stderr.Write(stdin)
 		fmt.Fprint(os.Stderr, "EOF\n")
 	}
-	stdout, stderr, _ := run(stdin, args)
+	stdout, stderr, _ := run(stdin, nargs)
 	if *debugGcc {
 		os.Stderr.Write(stdout)
 		os.Stderr.Write(stderr)
@@ -1279,8 +1388,7 @@ func runGcc(stdin []byte, args []string) (string, string) {
 // with equivalent memory layout.
 type typeConv struct {
 	// Cache of already-translated or in-progress types.
-	m       map[dwarf.Type]*Type
-	typedef map[string]ast.Expr
+	m map[dwarf.Type]*Type
 
 	// Map from types to incomplete pointers to those types.
 	ptrs map[dwarf.Type][]*Type
@@ -1372,7 +1480,7 @@ var dwarfToName = map[string]string{
 
 const signedDelta = 64
 
-// String returns the current type representation.  Format arguments
+// String returns the current type representation. Format arguments
 // are assembled within this method so that any changes in mutable
 // values are taken into account.
 func (tr *TypeRepr) String() string {
@@ -1812,7 +1920,7 @@ func (c *typeConv) FuncArg(dtype dwarf.Type, pos token.Pos) *Type {
 		}
 	case *dwarf.TypedefType:
 		// C has much more relaxed rules than Go for
-		// implicit type conversions.  When the parameter
+		// implicit type conversions. When the parameter
 		// is type T defined as *X, simulate a little of the
 		// laxness of C by making the argument *X instead of T.
 		if ptr, ok := base(dt.Type).(*dwarf.PtrType); ok {
@@ -1828,7 +1936,7 @@ func (c *typeConv) FuncArg(dtype dwarf.Type, pos token.Pos) *Type {
 			}
 
 			// Remember the C spelling, in case the struct
-			// has __attribute__((unavailable)) on it.  See issue 2888.
+			// has __attribute__((unavailable)) on it. See issue 2888.
 			t.Typedef = dt.Name
 		}
 	}
@@ -1843,7 +1951,7 @@ func (c *typeConv) FuncType(dtype *dwarf.FuncType, pos token.Pos) *FuncType {
 	for i, f := range dtype.ParamType {
 		// gcc's DWARF generator outputs a single DotDotDotType parameter for
 		// function pointers that specify no parameters (e.g. void
-		// (*__cgo_0)()).  Treat this special case as void.  This case is
+		// (*__cgo_0)()).  Treat this special case as void. This case is
 		// invalid according to ISO C anyway (i.e. void (*__cgo_1)(...) is not
 		// legal).
 		if _, ok := f.(*dwarf.DotDotDotType); ok && i == 0 {
@@ -1914,8 +2022,8 @@ func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.Struct
 	off := int64(0)
 
 	// Rename struct fields that happen to be named Go keywords into
-	// _{keyword}.  Create a map from C ident -> Go ident.  The Go ident will
-	// be mangled.  Any existing identifier that already has the same name on
+	// _{keyword}.  Create a map from C ident -> Go ident. The Go ident will
+	// be mangled. Any existing identifier that already has the same name on
 	// the C-side will cause the Go-mangled version to be prefixed with _.
 	// (e.g. in a struct with fields '_type' and 'type', the latter would be
 	// rendered as '__type' in Go).
@@ -1955,7 +2063,7 @@ func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.Struct
 
 		// In godefs mode, if this field is a C11
 		// anonymous union then treat the first field in the
-		// union as the field in the struct.  This handles
+		// union as the field in the struct. This handles
 		// cases like the glibc <sys/resource.h> file; see
 		// issue 6677.
 		if *godefs {
@@ -2025,7 +2133,7 @@ func (c *typeConv) Struct(dt *dwarf.StructType, pos token.Pos) (expr *ast.Struct
 	// We can't permit that, because then the size of the Go
 	// struct will not be the same as the size of the C struct.
 	// Our only option in such a case is to remove the field,
-	// which means that it can not be referenced from Go.
+	// which means that it cannot be referenced from Go.
 	for off > 0 && sizes[len(sizes)-1] == 0 {
 		n := len(sizes)
 		fld = fld[0 : n-1]
@@ -2079,7 +2187,7 @@ func godefsFields(fld []*ast.Field) {
 }
 
 // fieldPrefix returns the prefix that should be removed from all the
-// field names when generating the C or Go code.  For generated
+// field names when generating the C or Go code. For generated
 // C, we leave the names as is (tv_sec, tv_usec), since that's what
 // people are used to seeing in C.  For generated Go code, such as
 // package syscall's data structures, we drop a common prefix
@@ -2089,7 +2197,7 @@ func fieldPrefix(fld []*ast.Field) string {
 	for _, f := range fld {
 		for _, n := range f.Names {
 			// Ignore field names that don't have the prefix we're
-			// looking for.  It is common in C headers to have fields
+			// looking for. It is common in C headers to have fields
 			// named, say, _pad in an otherwise prefixed header.
 			// If the struct has 3 fields tv_sec, tv_usec, _pad1, then we
 			// still want to remove the tv_ prefix.
diff --git a/libgo/go/cmd/cgo/godefs.go b/libgo/go/cmd/cgo/godefs.go
index aff616ea578..6d638f06442 100644
--- a/libgo/go/cmd/cgo/godefs.go
+++ b/libgo/go/cmd/cgo/godefs.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/cgo/main.go b/libgo/go/cmd/cgo/main.go
index 6171b9d0672..219b2527323 100644
--- a/libgo/go/cmd/cgo/main.go
+++ b/libgo/go/cmd/cgo/main.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -42,7 +42,10 @@ type Package struct {
 	GoFiles     []string // list of Go files
 	GccFiles    []string // list of gcc output files
 	Preamble    string   // collected preamble for _cgo_export.h
-	CgoChecks   []string // see unsafeCheckPointerName
+
+	// See unsafeCheckPointerName.
+	CgoChecks         []string
+	DeferredCgoChecks []string
 }
 
 // A File collects information about a single Go input file.
@@ -52,7 +55,7 @@ type File struct {
 	Package  string              // Package name
 	Preamble string              // C preamble (doc comment on import "C")
 	Ref      []*Ref              // all references to C.xxx in AST
-	Calls    []*ast.CallExpr     // all calls to C.xxx in AST
+	Calls    []*Call             // all calls to C.xxx in AST
 	ExpFunc  []*ExpFunc          // exported functions for this file
 	Name     map[string]*Name    // map from Go name to Name
 }
@@ -66,6 +69,12 @@ func nameKeys(m map[string]*Name) []string {
 	return ks
 }
 
+// A Call refers to a call of a C.xxx function in the AST.
+type Call struct {
+	Call     *ast.CallExpr
+	Deferred bool
+}
+
 // A Ref refers to an expression of the form C.xxx in the AST.
 type Ref struct {
 	Name    *Name
@@ -208,9 +217,9 @@ func main() {
 
 	if *dynobj != "" {
 		// cgo -dynimport is essentially a separate helper command
-		// built into the cgo binary.  It scans a gcc-produced executable
+		// built into the cgo binary. It scans a gcc-produced executable
 		// and dumps information about the imported symbols and the
-		// imported libraries.  The 'go build' rules for cgo prepare an
+		// imported libraries. The 'go build' rules for cgo prepare an
 		// appropriate executable and then use its import information
 		// instead of needing to make the linkers duplicate all the
 		// specialized knowledge gcc has about where to look for imported
@@ -245,6 +254,12 @@ func main() {
 
 	goFiles := args[i:]
 
+	for _, arg := range args[:i] {
+		if arg == "-fsanitize=thread" {
+			tsanProlog = yesTsanProlog
+		}
+	}
+
 	p := newPackage(args[:i])
 
 	// Record CGO_LDFLAGS from the environment for external linking.
diff --git a/libgo/go/cmd/cgo/out.go b/libgo/go/cmd/cgo/out.go
index ca0ec0aaa28..842b1c5ef80 100644
--- a/libgo/go/cmd/cgo/out.go
+++ b/libgo/go/cmd/cgo/out.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -50,14 +50,16 @@ func (p *Package) writeDefs() {
 	// Write C main file for using gcc to resolve imports.
 	fmt.Fprintf(fm, "int main() { return 0; }\n")
 	if *importRuntimeCgo {
-		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int), void *a, int c) { }\n")
-		fmt.Fprintf(fm, "void _cgo_wait_runtime_init_done() { }\n")
+		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int, __SIZE_TYPE__), void *a, int c, __SIZE_TYPE__ ctxt) { }\n")
+		fmt.Fprintf(fm, "__SIZE_TYPE__ _cgo_wait_runtime_init_done() { return 0; }\n")
+		fmt.Fprintf(fm, "void _cgo_release_context(__SIZE_TYPE__ ctxt) { }\n")
 		fmt.Fprintf(fm, "char* _cgo_topofstack(void) { return (char*)0; }\n")
 	} else {
 		// If we're not importing runtime/cgo, we *are* runtime/cgo,
-		// which provides these functions.  We just need a prototype.
-		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int), void *a, int c);\n")
-		fmt.Fprintf(fm, "void _cgo_wait_runtime_init_done();\n")
+		// which provides these functions. We just need a prototype.
+		fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int, __SIZE_TYPE__), void *a, int c, __SIZE_TYPE__ ctxt);\n")
+		fmt.Fprintf(fm, "__SIZE_TYPE__ _cgo_wait_runtime_init_done();\n")
+		fmt.Fprintf(fm, "void _cgo_release_context(__SIZE_TYPE__);\n")
 	}
 	fmt.Fprintf(fm, "void _cgo_allocate(void *a, int c) { }\n")
 	fmt.Fprintf(fm, "void _cgo_panic(void *a, int c) { }\n")
@@ -110,7 +112,13 @@ func (p *Package) writeDefs() {
 	}
 
 	for i, t := range p.CgoChecks {
-		n := p.unsafeCheckPointerNameIndex(i)
+		n := p.unsafeCheckPointerNameIndex(i, false)
+		fmt.Fprintf(fgo2, "\nfunc %s(p %s, args ...interface{}) %s {\n", n, t, t)
+		fmt.Fprintf(fgo2, "\treturn _cgoCheckPointer(p, args...).(%s)\n", t)
+		fmt.Fprintf(fgo2, "}\n")
+	}
+	for i, t := range p.DeferredCgoChecks {
+		n := p.unsafeCheckPointerNameIndex(i, true)
 		fmt.Fprintf(fgo2, "\nfunc %s(p interface{}, args ...interface{}) %s {\n", n, t)
 		fmt.Fprintf(fgo2, "\treturn _cgoCheckPointer(p, args...).(%s)\n", t)
 		fmt.Fprintf(fgo2, "}\n")
@@ -173,10 +181,11 @@ func (p *Package) writeDefs() {
 	}
 	fmt.Fprintf(fgo2, "\n")
 
+	callsMalloc := false
 	for _, key := range nameKeys(p.Name) {
 		n := p.Name[key]
 		if n.FuncType != nil {
-			p.writeDefsFunc(fgo2, n)
+			p.writeDefsFunc(fgo2, n, &callsMalloc)
 		}
 	}
 
@@ -187,6 +196,12 @@ func (p *Package) writeDefs() {
 	} else {
 		p.writeExports(fgo2, fm, fgcc, fgcch)
 	}
+
+	if callsMalloc && !*gccgo {
+		fmt.Fprint(fgo2, strings.Replace(cMallocDefGo, "PREFIX", cPrefix, -1))
+		fmt.Fprint(fgcc, strings.Replace(strings.Replace(cMallocDefC, "PREFIX", cPrefix, -1), "PACKED", p.packedAttribute(), -1))
+	}
+
 	if err := fgcc.Close(); err != nil {
 		fatalf("%s", err)
 	}
@@ -350,7 +365,7 @@ func (p *Package) structType(n *Name) (string, int64) {
 	return buf.String(), off
 }
 
-func (p *Package) writeDefsFunc(fgo2 io.Writer, n *Name) {
+func (p *Package) writeDefsFunc(fgo2 io.Writer, n *Name, callsMalloc *bool) {
 	name := n.Go
 	gtype := n.FuncType.Go
 	void := gtype.Results == nil || len(gtype.Results.List) == 0
@@ -439,6 +454,9 @@ func (p *Package) writeDefsFunc(fgo2 io.Writer, n *Name) {
 
 	if inProlog {
 		fmt.Fprint(fgo2, builtinDefs[name])
+		if strings.Contains(builtinDefs[name], "_cgo_cmalloc") {
+			*callsMalloc = true
+		}
 		return
 	}
 
@@ -458,6 +476,7 @@ func (p *Package) writeDefsFunc(fgo2 io.Writer, n *Name) {
 	}
 
 	fmt.Fprint(fgo2, "\n")
+	fmt.Fprint(fgo2, "//go:cgo_unsafe_args\n")
 	conf.Fprint(fgo2, fset, d)
 	fmt.Fprint(fgo2, " {\n")
 
@@ -507,6 +526,7 @@ func (p *Package) writeOutput(f *File, srcfile string) {
 	// Gcc output starts with the preamble.
 	fmt.Fprintf(fgcc, "%s\n", f.Preamble)
 	fmt.Fprintf(fgcc, "%s\n", gccProlog)
+	fmt.Fprintf(fgcc, "%s\n", tsanProlog)
 
 	for _, key := range nameKeys(f.Name) {
 		n := f.Name[key]
@@ -531,6 +551,7 @@ func fixGo(name string) string {
 
 var isBuiltin = map[string]bool{
 	"_Cfunc_CString":   true,
+	"_Cfunc_CBytes":    true,
 	"_Cfunc_GoString":  true,
 	"_Cfunc_GoStringN": true,
 	"_Cfunc_GoBytes":   true,
@@ -555,6 +576,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 
 	// Gcc wrapper unpacks the C argument struct
 	// and calls the actual C function.
+	fmt.Fprintf(fgcc, "CGO_NO_SANITIZE_THREAD\n")
 	if n.AddError {
 		fmt.Fprintf(fgcc, "int\n")
 	} else {
@@ -563,7 +585,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 	fmt.Fprintf(fgcc, "_cgo%s%s(void *v)\n", cPrefix, n.Mangle)
 	fmt.Fprintf(fgcc, "{\n")
 	if n.AddError {
-		fmt.Fprintf(fgcc, "\terrno = 0;\n")
+		fmt.Fprintf(fgcc, "\tint _cgo_errno;\n")
 	}
 	// We're trying to write a gcc struct that matches gc's layout.
 	// Use packed attribute to force no padding in this struct in case
@@ -573,10 +595,18 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 		// Save the stack top for use below.
 		fmt.Fprintf(fgcc, "\tchar *stktop = _cgo_topofstack();\n")
 	}
+	tr := n.FuncType.Result
+	if tr != nil {
+		fmt.Fprintf(fgcc, "\t__typeof__(a->r) r;\n")
+	}
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
+	if n.AddError {
+		fmt.Fprintf(fgcc, "\terrno = 0;\n")
+	}
 	fmt.Fprintf(fgcc, "\t")
-	if t := n.FuncType.Result; t != nil {
-		fmt.Fprintf(fgcc, "__typeof__(a->r) r = ")
-		if c := t.C.String(); c[len(c)-1] == '*' {
+	if tr != nil {
+		fmt.Fprintf(fgcc, "r = ")
+		if c := tr.C.String(); c[len(c)-1] == '*' {
 			fmt.Fprint(fgcc, "(__typeof__(a->r)) ")
 		}
 	}
@@ -589,7 +619,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 		// the Go equivalents had good type params.
 		// However, our version of the type omits the magic
 		// words const and volatile, which can provoke
-		// C compiler warnings.  Silence them by casting
+		// C compiler warnings. Silence them by casting
 		// all pointers to void*.  (Eventually that will produce
 		// other warnings.)
 		if c := t.C.String(); c[len(c)-1] == '*' {
@@ -598,6 +628,10 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 		fmt.Fprintf(fgcc, "a->p%d", i)
 	}
 	fmt.Fprintf(fgcc, ");\n")
+	if n.AddError {
+		fmt.Fprintf(fgcc, "\t_cgo_errno = errno;\n")
+	}
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
 	if n.FuncType.Result != nil {
 		// The cgo call may have caused a stack copy (via a callback).
 		// Adjust the return value pointer appropriately.
@@ -606,18 +640,19 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 		fmt.Fprintf(fgcc, "\ta->r = r;\n")
 	}
 	if n.AddError {
-		fmt.Fprintf(fgcc, "\treturn errno;\n")
+		fmt.Fprintf(fgcc, "\treturn _cgo_errno;\n")
 	}
 	fmt.Fprintf(fgcc, "}\n")
 	fmt.Fprintf(fgcc, "\n")
 }
 
-// Write out a wrapper for a function when using gccgo.  This is a
-// simple wrapper that just calls the real function.  We only need a
+// Write out a wrapper for a function when using gccgo. This is a
+// simple wrapper that just calls the real function. We only need a
 // wrapper to support static functions in the prologue--without a
 // wrapper, we can't refer to the function, since the reference is in
 // a different file.
 func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
+	fmt.Fprintf(fgcc, "CGO_NO_SANITIZE_THREAD\n")
 	if t := n.FuncType.Result; t != nil {
 		fmt.Fprintf(fgcc, "%s\n", t.C.String())
 	} else {
@@ -636,9 +671,13 @@ func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
 	}
 	fmt.Fprintf(fgcc, ")\n")
 	fmt.Fprintf(fgcc, "{\n")
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "\t%s r;\n", t.C.String())
+	}
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
 	fmt.Fprintf(fgcc, "\t")
 	if t := n.FuncType.Result; t != nil {
-		fmt.Fprintf(fgcc, "return ")
+		fmt.Fprintf(fgcc, "r = ")
 		// Cast to void* to avoid warnings due to omitted qualifiers.
 		if c := t.C.String(); c[len(c)-1] == '*' {
 			fmt.Fprintf(fgcc, "(void*)")
@@ -656,6 +695,16 @@ func (p *Package) writeGccgoOutputFunc(fgcc *os.File, n *Name) {
 		fmt.Fprintf(fgcc, "p%d", i)
 	}
 	fmt.Fprintf(fgcc, ");\n")
+	fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
+	if t := n.FuncType.Result; t != nil {
+		fmt.Fprintf(fgcc, "\treturn ")
+		// Cast to void* to avoid warnings due to omitted qualifiers
+		// and explicit incompatible struct types.
+		if c := t.C.String(); c[len(c)-1] == '*' {
+			fmt.Fprintf(fgcc, "(void*)")
+		}
+		fmt.Fprintf(fgcc, "r;\n")
+	}
 	fmt.Fprintf(fgcc, "}\n")
 	fmt.Fprintf(fgcc, "\n")
 }
@@ -679,16 +728,20 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 	p.writeExportHeader(fgcch)
 
 	fmt.Fprintf(fgcc, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcc, "#include <stdlib.h>\n")
 	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n\n")
 
-	fmt.Fprintf(fgcc, "extern void crosscall2(void (*fn)(void *, int), void *, int);\n")
-	fmt.Fprintf(fgcc, "extern void _cgo_wait_runtime_init_done();\n\n")
+	fmt.Fprintf(fgcc, "extern void crosscall2(void (*fn)(void *, int, __SIZE_TYPE__), void *, int, __SIZE_TYPE__);\n")
+	fmt.Fprintf(fgcc, "extern __SIZE_TYPE__ _cgo_wait_runtime_init_done();\n")
+	fmt.Fprintf(fgcc, "extern void _cgo_release_context(__SIZE_TYPE__);\n\n")
+	fmt.Fprintf(fgcc, "extern char* _cgo_topofstack(void);")
+	fmt.Fprintf(fgcc, "%s\n", tsanProlog)
 
 	for _, exp := range p.ExpFunc {
 		fn := exp.Func
 
 		// Construct a gcc struct matching the gc argument and
-		// result frame.  The gcc struct will be compiled with
+		// result frame. The gcc struct will be compiled with
 		// __attribute__((packed)) so all padding must be accounted
 		// for explicitly.
 		ctype := "struct {\n"
@@ -783,10 +836,11 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		}
 		fmt.Fprintf(fgcch, "\nextern %s;\n", s)
 
-		fmt.Fprintf(fgcc, "extern void _cgoexp%s_%s(void *, int);\n", cPrefix, exp.ExpName)
+		fmt.Fprintf(fgcc, "extern void _cgoexp%s_%s(void *, int, __SIZE_TYPE__);\n", cPrefix, exp.ExpName)
+		fmt.Fprintf(fgcc, "\nCGO_NO_SANITIZE_THREAD")
 		fmt.Fprintf(fgcc, "\n%s\n", s)
 		fmt.Fprintf(fgcc, "{\n")
-		fmt.Fprintf(fgcc, "\t_cgo_wait_runtime_init_done();\n")
+		fmt.Fprintf(fgcc, "\t__SIZE_TYPE__ _cgo_ctxt = _cgo_wait_runtime_init_done();\n")
 		fmt.Fprintf(fgcc, "\t%s %v a;\n", ctype, p.packedAttribute())
 		if gccResult != "void" && (len(fntype.Results.List) > 1 || len(fntype.Results.List[0].Names) > 1) {
 			fmt.Fprintf(fgcc, "\t%s r;\n", gccResult)
@@ -798,7 +852,10 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 			func(i int, aname string, atype ast.Expr) {
 				fmt.Fprintf(fgcc, "\ta.p%d = p%d;\n", i, i)
 			})
-		fmt.Fprintf(fgcc, "\tcrosscall2(_cgoexp%s_%s, &a, %d);\n", cPrefix, exp.ExpName, off)
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
+		fmt.Fprintf(fgcc, "\tcrosscall2(_cgoexp%s_%s, &a, %d, _cgo_ctxt);\n", cPrefix, exp.ExpName, off)
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
+		fmt.Fprintf(fgcc, "\t_cgo_release_context(_cgo_ctxt);\n")
 		if gccResult != "void" {
 			if len(fntype.Results.List) == 1 && len(fntype.Results.List[0].Names) <= 1 {
 				fmt.Fprintf(fgcc, "\treturn a.r0;\n")
@@ -823,10 +880,10 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		fmt.Fprintf(fgo2, "//go:cgo_export_static _cgoexp%s_%s\n", cPrefix, exp.ExpName)
 		fmt.Fprintf(fgo2, "//go:nosplit\n") // no split stack, so no use of m or g
 		fmt.Fprintf(fgo2, "//go:norace\n")  // must not have race detector calls inserted
-		fmt.Fprintf(fgo2, "func _cgoexp%s_%s(a unsafe.Pointer, n int32) {\n", cPrefix, exp.ExpName)
+		fmt.Fprintf(fgo2, "func _cgoexp%s_%s(a unsafe.Pointer, n int32, ctxt uintptr) {\n", cPrefix, exp.ExpName)
 		fmt.Fprintf(fgo2, "\tfn := %s\n", goname)
 		// The indirect here is converting from a Go function pointer to a C function pointer.
-		fmt.Fprintf(fgo2, "\t_cgo_runtime_cgocallback(**(**unsafe.Pointer)(unsafe.Pointer(&fn)), a, uintptr(n));\n")
+		fmt.Fprintf(fgo2, "\t_cgo_runtime_cgocallback(**(**unsafe.Pointer)(unsafe.Pointer(&fn)), a, uintptr(n), ctxt);\n")
 		fmt.Fprintf(fgo2, "}\n")
 
 		fmt.Fprintf(fm, "int _cgoexp%s_%s;\n", cPrefix, exp.ExpName)
@@ -915,6 +972,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n")
 
 	fmt.Fprintf(fgcc, "%s\n", gccgoExportFileProlog)
+	fmt.Fprintf(fgcc, "%s\n", tsanProlog)
 
 	for _, exp := range p.ExpFunc {
 		fn := exp.Func
@@ -983,13 +1041,17 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		fmt.Fprintf(fgcc, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, goName)
 		fmt.Fprint(fgcc, "\n")
 
-		fmt.Fprint(fgcc, "\n")
+		fmt.Fprint(fgcc, "\nCGO_NO_SANITIZE_THREAD\n")
 		fmt.Fprintf(fgcc, "%s %s %s {\n", cRet, exp.ExpName, cParams)
+		if resultCount > 0 {
+			fmt.Fprintf(fgcc, "\t%s r;\n", cRet)
+		}
 		fmt.Fprintf(fgcc, "\tif(_cgo_wait_runtime_init_done)\n")
 		fmt.Fprintf(fgcc, "\t\t_cgo_wait_runtime_init_done();\n")
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_release();\n")
 		fmt.Fprint(fgcc, "\t")
 		if resultCount > 0 {
-			fmt.Fprint(fgcc, "return ")
+			fmt.Fprint(fgcc, "r = ")
 		}
 		fmt.Fprintf(fgcc, "%s(", goName)
 		if fn.Recv != nil {
@@ -1003,6 +1065,10 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 				fmt.Fprintf(fgcc, "p%d", i)
 			})
 		fmt.Fprint(fgcc, ");\n")
+		fmt.Fprintf(fgcc, "\t_cgo_tsan_acquire();\n")
+		if resultCount > 0 {
+			fmt.Fprint(fgcc, "\treturn r;\n")
+		}
 		fmt.Fprint(fgcc, "}\n")
 
 		// Dummy declaration for _cgo_main.c
@@ -1257,6 +1323,36 @@ extern char* _cgo_topofstack(void);
 #include <string.h>
 `
 
+// Prologue defining TSAN functions in C.
+const noTsanProlog = `
+#define CGO_NO_SANITIZE_THREAD
+#define _cgo_tsan_acquire()
+#define _cgo_tsan_release()
+`
+
+// This must match the TSAN code in runtime/cgo/libcgo.h.
+const yesTsanProlog = `
+#define CGO_NO_SANITIZE_THREAD __attribute__ ((no_sanitize_thread))
+
+long long _cgo_sync __attribute__ ((common));
+
+extern void __tsan_acquire(void*);
+extern void __tsan_release(void*);
+
+__attribute__ ((unused))
+static void _cgo_tsan_acquire() {
+	__tsan_acquire(&_cgo_sync);
+}
+
+__attribute__ ((unused))
+static void _cgo_tsan_release() {
+	__tsan_release(&_cgo_sync);
+}
+`
+
+// Set to yesTsanProlog if we see -fsanitize=thread in the flags for gcc.
+var tsanProlog = noTsanProlog
+
 const builtinProlog = `
 #include <stddef.h> /* for ptrdiff_t and size_t below */
 
@@ -1269,6 +1365,7 @@ _GoString_ GoString(char *p);
 _GoString_ GoStringN(char *p, int l);
 _GoBytes_ GoBytes(void *p, int n);
 char *CString(_GoString_);
+void *CBytes(_GoBytes_);
 void *_CMalloc(size_t);
 `
 
@@ -1276,11 +1373,8 @@ const goProlog = `
 //go:linkname _cgo_runtime_cgocall runtime.cgocall
 func _cgo_runtime_cgocall(unsafe.Pointer, uintptr) int32
 
-//go:linkname _cgo_runtime_cmalloc runtime.cmalloc
-func _cgo_runtime_cmalloc(uintptr) unsafe.Pointer
-
 //go:linkname _cgo_runtime_cgocallback runtime.cgocallback
-func _cgo_runtime_cgocallback(unsafe.Pointer, unsafe.Pointer, uintptr)
+func _cgo_runtime_cgocallback(unsafe.Pointer, unsafe.Pointer, uintptr, uintptr)
 
 //go:linkname _cgoCheckPointer runtime.cgoCheckPointer
 func _cgoCheckPointer(interface{}, ...interface{}) interface{}
@@ -1324,7 +1418,7 @@ func _Cfunc_GoBytes(p unsafe.Pointer, l _Ctype_int) []byte {
 
 const cStringDef = `
 func _Cfunc_CString(s string) *_Ctype_char {
-	p := _cgo_runtime_cmalloc(uintptr(len(s)+1))
+	p := _cgo_cmalloc(uint64(len(s)+1))
 	pp := (*[1<<30]byte)(p)
 	copy(pp[:], s)
 	pp[len(s)] = 0
@@ -1332,9 +1426,18 @@ func _Cfunc_CString(s string) *_Ctype_char {
 }
 `
 
+const cBytesDef = `
+func _Cfunc_CBytes(b []byte) unsafe.Pointer {
+	p := _cgo_cmalloc(uint64(len(b)))
+	pp := (*[1<<30]byte)(p)
+	copy(pp[:], b)
+	return p
+}
+`
+
 const cMallocDef = `
 func _Cfunc__CMalloc(n _Ctype_size_t) unsafe.Pointer {
-	return _cgo_runtime_cmalloc(uintptr(n))
+	return _cgo_cmalloc(uint64(n))
 }
 `
 
@@ -1343,9 +1446,54 @@ var builtinDefs = map[string]string{
 	"GoStringN": goStringNDef,
 	"GoBytes":   goBytesDef,
 	"CString":   cStringDef,
+	"CBytes":    cBytesDef,
 	"_CMalloc":  cMallocDef,
 }
 
+// Definitions for C.malloc in Go and in C. We define it ourselves
+// since we call it from functions we define, such as C.CString.
+// Also, we have historically ensured that C.malloc does not return
+// nil even for an allocation of 0.
+
+const cMallocDefGo = `
+//go:cgo_import_static _cgoPREFIX_Cfunc__Cmalloc
+//go:linkname __cgofn__cgoPREFIX_Cfunc__Cmalloc _cgoPREFIX_Cfunc__Cmalloc
+var __cgofn__cgoPREFIX_Cfunc__Cmalloc byte
+var _cgoPREFIX_Cfunc__Cmalloc = unsafe.Pointer(&__cgofn__cgoPREFIX_Cfunc__Cmalloc)
+
+//go:cgo_unsafe_args
+func _cgo_cmalloc(p0 uint64) (r1 unsafe.Pointer) {
+	_cgo_runtime_cgocall(_cgoPREFIX_Cfunc__Cmalloc, uintptr(unsafe.Pointer(&p0)))
+	return
+}
+`
+
+// cMallocDefC defines the C version of C.malloc for the gc compiler.
+// It is defined here because C.CString and friends need a definition.
+// We define it by hand, rather than simply inventing a reference to
+// C.malloc, because <stdlib.h> may not have been included.
+// This is approximately what writeOutputFunc would generate, but
+// skips the cgo_topofstack code (which is only needed if the C code
+// calls back into Go). This also avoids returning nil for an
+// allocation of 0 bytes.
+const cMallocDefC = `
+CGO_NO_SANITIZE_THREAD
+void _cgoPREFIX_Cfunc__Cmalloc(void *v) {
+	struct {
+		unsigned long long p0;
+		void *r1;
+	} PACKED *a = v;
+	void *ret;
+	_cgo_tsan_acquire();
+	ret = malloc(a->p0);
+	if (ret == 0 && a->p0 == 0) {
+		ret = malloc(1);
+	}
+	a->r1 = ret;
+	_cgo_tsan_release();
+}
+`
+
 func (p *Package) cPrologGccgo() string {
 	return strings.Replace(strings.Replace(cPrologGccgo, "PREFIX", cPrefix, -1),
 		"GCCGOSYMBOLPREF", p.gccgoSymbolPrefix(), -1)
@@ -1380,6 +1528,12 @@ const char *_cgoPREFIX_Cfunc_CString(struct __go_string s) {
 	return p;
 }
 
+void *_cgoPREFIX_Cfunc_CBytes(struct __go_open_array b) {
+	char *p = malloc(b.__count);
+	memmove(p, b.__values, b.__count);
+	return p;
+}
+
 struct __go_string _cgoPREFIX_Cfunc_GoString(char *p) {
 	intgo len = (p != NULL) ? strlen(p) : 0;
 	return __go_byte_array_to_string(p, len);
@@ -1505,5 +1659,5 @@ static void GoInit(void) {
 		runtime_iscgo = 1;
 }
 
-extern void _cgo_wait_runtime_init_done() __attribute__ ((weak));
+extern __SIZE_TYPE__ _cgo_wait_runtime_init_done() __attribute__ ((weak));
 `
diff --git a/libgo/go/cmd/cgo/util.go b/libgo/go/cmd/cgo/util.go
index 3adb8e87836..4f5c48864e9 100644
--- a/libgo/go/cmd/cgo/util.go
+++ b/libgo/go/cmd/cgo/util.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"go/token"
+	"io/ioutil"
 	"os"
 	"os/exec"
 )
@@ -16,6 +17,43 @@ import (
 // It returns the output to standard output and standard error.
 // ok indicates whether the command exited successfully.
 func run(stdin []byte, argv []string) (stdout, stderr []byte, ok bool) {
+	if i := find(argv, "-xc"); i >= 0 && argv[len(argv)-1] == "-" {
+		// Some compilers have trouble with standard input.
+		// Others have trouble with -xc.
+		// Avoid both problems by writing a file with a .c extension.
+		f, err := ioutil.TempFile("", "cgo-gcc-input-")
+		if err != nil {
+			fatalf("%s", err)
+		}
+		name := f.Name()
+		f.Close()
+		if err := ioutil.WriteFile(name+".c", stdin, 0666); err != nil {
+			os.Remove(name)
+			fatalf("%s", err)
+		}
+		defer os.Remove(name)
+		defer os.Remove(name + ".c")
+
+		// Build new argument list without -xc and trailing -.
+		new := append(argv[:i:i], argv[i+1:len(argv)-1]...)
+
+		// Since we are going to write the file to a temporary directory,
+		// we will need to add -I . explicitly to the command line:
+		// any #include "foo" before would have looked in the current
+		// directory as the directory "holding" standard input, but now
+		// the temporary directory holds the input.
+		// We've also run into compilers that reject "-I." but allow "-I", ".",
+		// so be sure to use two arguments.
+		// This matters mainly for people invoking cgo -godefs by hand.
+		new = append(new, "-I", ".")
+
+		// Finish argument list with path to C file.
+		new = append(new, name+".c")
+
+		argv = new
+		stdin = nil
+	}
+
 	p := exec.Command(argv[0], argv[1:]...)
 	p.Stdin = bytes.NewReader(stdin)
 	var bout, berr bytes.Buffer
@@ -30,6 +68,15 @@ func run(stdin []byte, argv []string) (stdout, stderr []byte, ok bool) {
 	return
 }
 
+func find(argv []string, target string) int {
+	for i, arg := range argv {
+		if arg == target {
+			return i
+		}
+	}
+	return -1
+}
+
 func lineno(pos token.Pos) string {
 	return fset.Position(pos).String()
 }
@@ -37,7 +84,7 @@ func lineno(pos token.Pos) string {
 // Die with an error message.
 func fatalf(msg string, args ...interface{}) {
 	// If we've already printed other errors, they might have
-	// caused the fatal condition.  Assume they're enough.
+	// caused the fatal condition. Assume they're enough.
 	if nerrors == 0 {
 		fmt.Fprintf(os.Stderr, msg+"\n", args...)
 	}
diff --git a/libgo/go/cmd/go/alldocs.go b/libgo/go/cmd/go/alldocs.go
index c81bd40864a..58b0d16b2b0 100644
--- a/libgo/go/cmd/go/alldocs.go
+++ b/libgo/go/cmd/go/alldocs.go
@@ -1,1575 +1,1591 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // DO NOT EDIT THIS FILE. GENERATED BY mkalldocs.sh.
 // Edit the documentation in other files and rerun mkalldocs.sh to generate this one.
 
-/*
-Go is a tool for managing Go source code.
-
-Usage:
-
-	go command [arguments]
-
-The commands are:
-
-	build       compile packages and dependencies
-	clean       remove object files
-	doc         show documentation for package or symbol
-	env         print Go environment information
-	fix         run go tool fix on packages
-	fmt         run gofmt on package sources
-	generate    generate Go files by processing source
-	get         download and install packages and dependencies
-	install     compile and install packages and dependencies
-	list        list packages
-	run         compile and run Go program
-	test        test packages
-	tool        run specified go tool
-	version     print Go version
-	vet         run go tool vet on packages
-
-Use "go help [command]" for more information about a command.
-
-Additional help topics:
-
-	c           calling between Go and C
-	buildmode   description of build modes
-	filetype    file types
-	gopath      GOPATH environment variable
-	environment environment variables
-	importpath  import path syntax
-	packages    description of package lists
-	testflag    description of testing flags
-	testfunc    description of testing functions
-
-Use "go help [topic]" for more information about that topic.
-
-
-Compile packages and dependencies
-
-Usage:
-
-	go build [-o output] [-i] [build flags] [packages]
-
-Build compiles the packages named by the import paths,
-along with their dependencies, but it does not install the results.
-
-If the arguments to build are a list of .go files, build treats
-them as a list of source files specifying a single package.
-
-When compiling a single main package, build writes
-the resulting executable to an output file named after
-the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe')
-or the source code directory ('go build unix/sam' writes 'sam' or 'sam.exe').
-The '.exe' suffix is added when writing a Windows executable.
-
-When compiling multiple packages or a single non-main package,
-build compiles the packages but discards the resulting object,
-serving only as a check that the packages can be built.
-
-The -o flag, only allowed when compiling a single package,
-forces build to write the resulting executable or object
-to the named output file, instead of the default behavior described
-in the last two paragraphs.
-
-The -i flag installs the packages that are dependencies of the target.
-
-The build flags are shared by the build, clean, get, install, list, run,
-and test commands:
-
-	-a
-		force rebuilding of packages that are already up-to-date.
-	-n
-		print the commands but do not run them.
-	-p n
-		the number of programs, such as build commands or
-		test binaries, that can be run in parallel.
-		The default is the number of CPUs available, except
-		on darwin/arm which defaults to 1.
-	-race
-		enable data race detection.
-		Supported only on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64.
-	-msan
-		enable interoperation with memory sanitizer.
-		Supported only on linux/amd64,
-		and only with Clang/LLVM as the host C compiler.
-	-v
-		print the names of packages as they are compiled.
-	-work
-		print the name of the temporary work directory and
-		do not delete it when exiting.
-	-x
-		print the commands.
-
-	-asmflags 'flag list'
-		arguments to pass on each go tool asm invocation.
-	-buildmode mode
-		build mode to use. See 'go help buildmode' for more.
-	-compiler name
-		name of compiler to use, as in runtime.Compiler (gccgo or gc).
-	-gccgoflags 'arg list'
-		arguments to pass on each gccgo compiler/linker invocation.
-	-gcflags 'arg list'
-		arguments to pass on each go tool compile invocation.
-	-installsuffix suffix
-		a suffix to use in the name of the package installation directory,
-		in order to keep output separate from default builds.
-		If using the -race flag, the install suffix is automatically set to race
-		or, if set explicitly, has _race appended to it.  Likewise for the -msan
-		flag.  Using a -buildmode option that requires non-default compile flags
-		has a similar effect.
-	-ldflags 'flag list'
-		arguments to pass on each go tool link invocation.
-	-linkshared
-		link against shared libraries previously created with
-		-buildmode=shared.
-	-pkgdir dir
-		install and load all packages from dir instead of the usual locations.
-		For example, when building with a non-standard configuration,
-		use -pkgdir to keep generated packages in a separate location.
-	-tags 'tag list'
-		a list of build tags to consider satisfied during the build.
-		For more information about build tags, see the description of
-		build constraints in the documentation for the go/build package.
-	-toolexec 'cmd args'
-		a program to use to invoke toolchain programs like vet and asm.
-		For example, instead of running asm, the go command will run
-		'cmd args /path/to/asm <arguments for asm>'.
-
-The list flags accept a space-separated list of strings. To embed spaces
-in an element in the list, surround it with either single or double quotes.
-
-For more about specifying packages, see 'go help packages'.
-For more about where packages and binaries are installed,
-run 'go help gopath'.
-For more about calling between Go and C/C++, run 'go help c'.
-
-Note: Build adheres to certain conventions such as those described
-by 'go help gopath'. Not all projects can follow these conventions,
-however. Installations that have their own conventions or that use
-a separate software build system may choose to use lower-level
-invocations such as 'go tool compile' and 'go tool link' to avoid
-some of the overheads and design decisions of the build tool.
-
-See also: go install, go get, go clean.
-
-
-Remove object files
-
-Usage:
-
-	go clean [-i] [-r] [-n] [-x] [build flags] [packages]
-
-Clean removes object files from package source directories.
-The go command builds most objects in a temporary directory,
-so go clean is mainly concerned with object files left by other
-tools or by manual invocations of go build.
-
-Specifically, clean removes the following files from each of the
-source directories corresponding to the import paths:
-
-	_obj/            old object directory, left from Makefiles
-	_test/           old test directory, left from Makefiles
-	_testmain.go     old gotest file, left from Makefiles
-	test.out         old test log, left from Makefiles
-	build.out        old test log, left from Makefiles
-	*.[568ao]        object files, left from Makefiles
-
-	DIR(.exe)        from go build
-	DIR.test(.exe)   from go test -c
-	MAINFILE(.exe)   from go build MAINFILE.go
-	*.so             from SWIG
-
-In the list, DIR represents the final path element of the
-directory, and MAINFILE is the base name of any Go source
-file in the directory that is not included when building
-the package.
-
-The -i flag causes clean to remove the corresponding installed
-archive or binary (what 'go install' would create).
-
-The -n flag causes clean to print the remove commands it would execute,
-but not run them.
-
-The -r flag causes clean to be applied recursively to all the
-dependencies of the packages named by the import paths.
-
-The -x flag causes clean to print remove commands as it executes them.
-
-For more about build flags, see 'go help build'.
-
-For more about specifying packages, see 'go help packages'.
-
-
-Show documentation for package or symbol
-
-Usage:
-
-	go doc [-u] [-c] [package|[package.]symbol[.method]]
-
-Doc prints the documentation comments associated with the item identified by its
-arguments (a package, const, func, type, var, or method) followed by a one-line
-summary of each of the first-level items "under" that item (package-level
-declarations for a package, methods for a type, etc.).
-
-Doc accepts zero, one, or two arguments.
-
-Given no arguments, that is, when run as
-
-	go doc
-
-it prints the package documentation for the package in the current directory.
-If the package is a command (package main), the exported symbols of the package
-are elided from the presentation unless the -cmd flag is provided.
-
-When run with one argument, the argument is treated as a Go-syntax-like
-representation of the item to be documented. What the argument selects depends
-on what is installed in GOROOT and GOPATH, as well as the form of the argument,
-which is schematically one of these:
-
-	go doc <pkg>
-	go doc <sym>[.<method>]
-	go doc [<pkg>.]<sym>[.<method>]
-	go doc [<pkg>.][<sym>.]<method>
-
-The first item in this list matched by the argument is the one whose documentation
-is printed. (See the examples below.) However, if the argument starts with a capital
-letter it is assumed to identify a symbol or method in the current directory.
-
-For packages, the order of scanning is determined lexically in breadth-first order.
-That is, the package presented is the one that matches the search and is nearest
-the root and lexically first at its level of the hierarchy.  The GOROOT tree is
-always scanned in its entirety before GOPATH.
-
-If there is no package specified or matched, the package in the current
-directory is selected, so "go doc Foo" shows the documentation for symbol Foo in
-the current package.
-
-The package path must be either a qualified path or a proper suffix of a
-path. The go tool's usual package mechanism does not apply: package path
-elements like . and ... are not implemented by go doc.
-
-When run with two arguments, the first must be a full package path (not just a
-suffix), and the second is a symbol or symbol and method; this is similar to the
-syntax accepted by godoc:
-
-	go doc <pkg> <sym>[.<method>]
-
-In all forms, when matching symbols, lower-case letters in the argument match
-either case but upper-case letters match exactly. This means that there may be
-multiple matches of a lower-case argument in a package if different symbols have
-different cases. If this occurs, documentation for all matches is printed.
-
-Examples:
-	go doc
-		Show documentation for current package.
-	go doc Foo
-		Show documentation for Foo in the current package.
-		(Foo starts with a capital letter so it cannot match
-		a package path.)
-	go doc encoding/json
-		Show documentation for the encoding/json package.
-	go doc json
-		Shorthand for encoding/json.
-	go doc json.Number (or go doc json.number)
-		Show documentation and method summary for json.Number.
-	go doc json.Number.Int64 (or go doc json.number.int64)
-		Show documentation for json.Number's Int64 method.
-	go doc cmd/doc
-		Show package docs for the doc command.
-	go doc -cmd cmd/doc
-		Show package docs and exported symbols within the doc command.
-	go doc template.new
-		Show documentation for html/template's New function.
-		(html/template is lexically before text/template)
-	go doc text/template.new # One argument
-		Show documentation for text/template's New function.
-	go doc text/template new # Two arguments
-		Show documentation for text/template's New function.
-
-	At least in the current tree, these invocations all print the
-	documentation for json.Decoder's Decode method:
-
-	go doc json.Decoder.Decode
-	go doc json.decoder.decode
-	go doc json.decode
-	cd go/src/encoding/json; go doc decode
-
-Flags:
-	-c
-		Respect case when matching symbols.
-	-cmd
-		Treat a command (package main) like a regular package.
-		Otherwise package main's exported symbols are hidden
-		when showing the package's top-level documentation.
-	-u
-		Show documentation for unexported as well as exported
-		symbols and methods.
-
-
-Print Go environment information
-
-Usage:
-
-	go env [var ...]
-
-Env prints Go environment information.
-
-By default env prints information as a shell script
-(on Windows, a batch file).  If one or more variable
-names is given as arguments,  env prints the value of
-each named variable on its own line.
-
-
-Run go tool fix on packages
-
-Usage:
-
-	go fix [packages]
-
-Fix runs the Go fix command on the packages named by the import paths.
-
-For more about fix, see 'go doc cmd/fix'.
-For more about specifying packages, see 'go help packages'.
-
-To run fix with specific options, run 'go tool fix'.
-
-See also: go fmt, go vet.
-
-
-Run gofmt on package sources
-
-Usage:
-
-	go fmt [-n] [-x] [packages]
-
-Fmt runs the command 'gofmt -l -w' on the packages named
-by the import paths.  It prints the names of the files that are modified.
-
-For more about gofmt, see 'go doc cmd/gofmt'.
-For more about specifying packages, see 'go help packages'.
-
-The -n flag prints commands that would be executed.
-The -x flag prints commands as they are executed.
-
-To run gofmt with specific options, run gofmt itself.
-
-See also: go fix, go vet.
-
-
-Generate Go files by processing source
-
-Usage:
-
-	go generate [-run regexp] [-n] [-v] [-x] [build flags] [file.go... | packages]
-
-Generate runs commands described by directives within existing
-files. Those commands can run any process but the intent is to
-create or update Go source files, for instance by running yacc.
-
-Go generate is never run automatically by go build, go get, go test,
-and so on. It must be run explicitly.
-
-Go generate scans the file for directives, which are lines of
-the form,
-
-	//go:generate command argument...
-
-(note: no leading spaces and no space in "//go") where command
-is the generator to be run, corresponding to an executable file
-that can be run locally. It must either be in the shell path
-(gofmt), a fully qualified path (/usr/you/bin/mytool), or a
-command alias, described below.
-
-Note that go generate does not parse the file, so lines that look
-like directives in comments or multiline strings will be treated
-as directives.
-
-The arguments to the directive are space-separated tokens or
-double-quoted strings passed to the generator as individual
-arguments when it is run.
-
-Quoted strings use Go syntax and are evaluated before execution; a
-quoted string appears as a single argument to the generator.
-
-Go generate sets several variables when it runs the generator:
-
-	$GOARCH
-		The execution architecture (arm, amd64, etc.)
-	$GOOS
-		The execution operating system (linux, windows, etc.)
-	$GOFILE
-		The base name of the file.
-	$GOLINE
-		The line number of the directive in the source file.
-	$GOPACKAGE
-		The name of the package of the file containing the directive.
-	$DOLLAR
-		A dollar sign.
-
-Other than variable substitution and quoted-string evaluation, no
-special processing such as "globbing" is performed on the command
-line.
-
-As a last step before running the command, any invocations of any
-environment variables with alphanumeric names, such as $GOFILE or
-$HOME, are expanded throughout the command line. The syntax for
-variable expansion is $NAME on all operating systems.  Due to the
-order of evaluation, variables are expanded even inside quoted
-strings. If the variable NAME is not set, $NAME expands to the
-empty string.
-
-A directive of the form,
-
-	//go:generate -command xxx args...
-
-specifies, for the remainder of this source file only, that the
-string xxx represents the command identified by the arguments. This
-can be used to create aliases or to handle multiword generators.
-For example,
-
-	//go:generate -command yacc go tool yacc
-
-specifies that the command "yacc" represents the generator
-"go tool yacc".
-
-Generate processes packages in the order given on the command line,
-one at a time. If the command line lists .go files, they are treated
-as a single package. Within a package, generate processes the
-source files in a package in file name order, one at a time. Within
-a source file, generate runs generators in the order they appear
-in the file, one at a time.
-
-If any generator returns an error exit status, "go generate" skips
-all further processing for that package.
-
-The generator is run in the package's source directory.
-
-Go generate accepts one specific flag:
-
-	-run=""
-		if non-empty, specifies a regular expression to select
-		directives whose full original source text (excluding
-		any trailing spaces and final newline) matches the
-		expression.
-
-It also accepts the standard build flags including -v, -n, and -x.
-The -v flag prints the names of packages and files as they are
-processed.
-The -n flag prints commands that would be executed.
-The -x flag prints commands as they are executed.
-
-For more about build flags, see 'go help build'.
-
-For more about specifying packages, see 'go help packages'.
-
-
-Download and install packages and dependencies
-
-Usage:
-
-	go get [-d] [-f] [-fix] [-insecure] [-t] [-u] [build flags] [packages]
-
-Get downloads and installs the packages named by the import paths,
-along with their dependencies.
-
-The -d flag instructs get to stop after downloading the packages; that is,
-it instructs get not to install the packages.
-
-The -f flag, valid only when -u is set, forces get -u not to verify that
-each package has been checked out from the source control repository
-implied by its import path. This can be useful if the source is a local fork
-of the original.
-
-The -fix flag instructs get to run the fix tool on the downloaded packages
-before resolving dependencies or building the code.
-
-The -insecure flag permits fetching from repositories and resolving
-custom domains using insecure schemes such as HTTP. Use with caution.
-
-The -t flag instructs get to also download the packages required to build
-the tests for the specified packages.
-
-The -u flag instructs get to use the network to update the named packages
-and their dependencies.  By default, get uses the network to check out
-missing packages but does not use it to look for updates to existing packages.
-
-Get also accepts build flags to control the installation. See 'go help build'.
-
-When checking out a new package, get creates the target directory
-GOPATH/src/<import-path>. If the GOPATH contains multiple entries,
-get uses the first one. See 'go help gopath'.
-
-When checking out or updating a package, get looks for a branch or tag
-that matches the locally installed version of Go. The most important
-rule is that if the local installation is running version "go1", get
-searches for a branch or tag named "go1". If no such version exists it
-retrieves the most recent version of the package.
-
-Unless vendoring support is disabled (see 'go help gopath'),
-when go get checks out or updates a Git repository,
-it also updates any git submodules referenced by the repository.
-
-Get never checks out or updates code stored in vendor directories.
-
-For more about specifying packages, see 'go help packages'.
-
-For more about how 'go get' finds source code to
-download, see 'go help importpath'.
-
-See also: go build, go install, go clean.
-
-
-Compile and install packages and dependencies
-
-Usage:
-
-	go install [build flags] [packages]
-
-Install compiles and installs the packages named by the import paths,
-along with their dependencies.
-
-For more about the build flags, see 'go help build'.
-For more about specifying packages, see 'go help packages'.
-
-See also: go build, go get, go clean.
-
-
-List packages
-
-Usage:
-
-	go list [-e] [-f format] [-json] [build flags] [packages]
-
-List lists the packages named by the import paths, one per line.
-
-The default output shows the package import path:
-
-    bytes
-    encoding/json
-    github.com/gorilla/mux
-    golang.org/x/net/html
-
-The -f flag specifies an alternate format for the list, using the
-syntax of package template.  The default output is equivalent to -f
-'{{.ImportPath}}'. The struct being passed to the template is:
-
-    type Package struct {
-        Dir           string // directory containing package sources
-        ImportPath    string // import path of package in dir
-        ImportComment string // path in import comment on package statement
-        Name          string // package name
-        Doc           string // package documentation string
-        Target        string // install path
-        Shlib         string // the shared library that contains this package (only set when -linkshared)
-        Goroot        bool   // is this package in the Go root?
-        Standard      bool   // is this package part of the standard Go library?
-        Stale         bool   // would 'go install' do anything for this package?
-        Root          string // Go root or Go path dir containing this package
-
-        // Source files
-        GoFiles        []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
-        CgoFiles       []string // .go sources files that import "C"
-        IgnoredGoFiles []string // .go sources ignored due to build constraints
-        CFiles         []string // .c source files
-        CXXFiles       []string // .cc, .cxx and .cpp source files
-        MFiles         []string // .m source files
-        HFiles         []string // .h, .hh, .hpp and .hxx source files
-        SFiles         []string // .s source files
-        SwigFiles      []string // .swig files
-        SwigCXXFiles   []string // .swigcxx files
-        SysoFiles      []string // .syso object files to add to archive
-
-        // Cgo directives
-        CgoCFLAGS    []string // cgo: flags for C compiler
-        CgoCPPFLAGS  []string // cgo: flags for C preprocessor
-        CgoCXXFLAGS  []string // cgo: flags for C++ compiler
-        CgoLDFLAGS   []string // cgo: flags for linker
-        CgoPkgConfig []string // cgo: pkg-config names
-
-        // Dependency information
-        Imports []string // import paths used by this package
-        Deps    []string // all (recursively) imported dependencies
-
-        // Error information
-        Incomplete bool            // this package or a dependency has an error
-        Error      *PackageError   // error loading package
-        DepsErrors []*PackageError // errors loading dependencies
-
-        TestGoFiles  []string // _test.go files in package
-        TestImports  []string // imports from TestGoFiles
-        XTestGoFiles []string // _test.go files outside package
-        XTestImports []string // imports from XTestGoFiles
-    }
-
-The error information, if any, is
-
-    type PackageError struct {
-        ImportStack   []string // shortest path from package named on command line to this one
-        Pos           string   // position of error (if present, file:line:col)
-        Err           string   // the error itself
-    }
-
-The template function "join" calls strings.Join.
-
-The template function "context" returns the build context, defined as:
-
-	type Context struct {
-		GOARCH        string   // target architecture
-		GOOS          string   // target operating system
-		GOROOT        string   // Go root
-		GOPATH        string   // Go path
-		CgoEnabled    bool     // whether cgo can be used
-		UseAllFiles   bool     // use files regardless of +build lines, file names
-		Compiler      string   // compiler to assume when computing target paths
-		BuildTags     []string // build constraints to match in +build lines
-		ReleaseTags   []string // releases the current release is compatible with
-		InstallSuffix string   // suffix to use in the name of the install dir
-	}
-
-For more information about the meaning of these fields see the documentation
-for the go/build package's Context type.
-
-The -json flag causes the package data to be printed in JSON format
-instead of using the template format.
-
-The -e flag changes the handling of erroneous packages, those that
-cannot be found or are malformed.  By default, the list command
-prints an error to standard error for each erroneous package and
-omits the packages from consideration during the usual printing.
-With the -e flag, the list command never prints errors to standard
-error and instead processes the erroneous packages with the usual
-printing.  Erroneous packages will have a non-empty ImportPath and
-a non-nil Error field; other information may or may not be missing
-(zeroed).
-
-For more about build flags, see 'go help build'.
-
-For more about specifying packages, see 'go help packages'.
-
-
-Compile and run Go program
-
-Usage:
-
-	go run [build flags] [-exec xprog] gofiles... [arguments...]
-
-Run compiles and runs the main package comprising the named Go source files.
-A Go source file is defined to be a file ending in a literal ".go" suffix.
-
-By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
-If the -exec flag is given, 'go run' invokes the binary using xprog:
-	'xprog a.out arguments...'.
-If the -exec flag is not given, GOOS or GOARCH is different from the system
-default, and a program named go_$GOOS_$GOARCH_exec can be found
-on the current search path, 'go run' invokes the binary using that program,
-for example 'go_nacl_386_exec a.out arguments...'. This allows execution of
-cross-compiled programs when a simulator or other execution method is
-available.
-
-For more about build flags, see 'go help build'.
-
-See also: go build.
-
-
-Test packages
-
-Usage:
-
-	go test [build/test flags] [packages] [build/test flags & test binary flags]
-
-'Go test' automates testing the packages named by the import paths.
-It prints a summary of the test results in the format:
-
-	ok   archive/tar   0.011s
-	FAIL archive/zip   0.022s
-	ok   compress/gzip 0.033s
-	...
-
-followed by detailed output for each failed package.
-
-'Go test' recompiles each package along with any files with names matching
-the file pattern "*_test.go".
-Files whose names begin with "_" (including "_test.go") or "." are ignored.
-These additional files can contain test functions, benchmark functions, and
-example functions.  See 'go help testfunc' for more.
-Each listed package causes the execution of a separate test binary.
-
-Test files that declare a package with the suffix "_test" will be compiled as a
-separate package, and then linked and run with the main test binary.
-
-By default, go test needs no arguments.  It compiles and tests the package
-with source in the current directory, including tests, and runs the tests.
-
-The package is built in a temporary directory so it does not interfere with the
-non-test installation.
-
-In addition to the build flags, the flags handled by 'go test' itself are:
-
-	-args
-	    Pass the remainder of the command line (everything after -args)
-	    to the test binary, uninterpreted and unchanged.
-	    Because this flag consumes the remainder of the command line,
-	    the package list (if present) must appear before this flag.
-
-	-c
-	    Compile the test binary to pkg.test but do not run it
-	    (where pkg is the last element of the package's import path).
-	    The file name can be changed with the -o flag.
-
-	-exec xprog
-	    Run the test binary using xprog. The behavior is the same as
-	    in 'go run'. See 'go help run' for details.
-
-	-i
-	    Install packages that are dependencies of the test.
-	    Do not run the test.
-
-	-o file
-	    Compile the test binary to the named file.
-	    The test still runs (unless -c or -i is specified).
-
-The test binary also accepts flags that control execution of the test; these
-flags are also accessible by 'go test'. See 'go help testflag' for details.
-
-For more about build flags, see 'go help build'.
-For more about specifying packages, see 'go help packages'.
-
-See also: go build, go vet.
-
-
-Run specified go tool
-
-Usage:
-
-	go tool [-n] command [args...]
-
-Tool runs the go tool command identified by the arguments.
-With no arguments it prints the list of known tools.
-
-The -n flag causes tool to print the command that would be
-executed but not execute it.
-
-For more about each tool command, see 'go tool command -h'.
-
-
-Print Go version
-
-Usage:
-
-	go version
-
-Version prints the Go version, as reported by runtime.Version.
-
-
-Run go tool vet on packages
-
-Usage:
-
-	go vet [-n] [-x] [build flags] [packages]
-
-Vet runs the Go vet command on the packages named by the import paths.
-
-For more about vet, see 'go doc cmd/vet'.
-For more about specifying packages, see 'go help packages'.
-
-To run the vet tool with specific options, run 'go tool vet'.
-
-The -n flag prints commands that would be executed.
-The -x flag prints commands as they are executed.
-
-For more about build flags, see 'go help build'.
-
-See also: go fmt, go fix.
-
-
-Calling between Go and C
-
-There are two different ways to call between Go and C/C++ code.
-
-The first is the cgo tool, which is part of the Go distribution.  For
-information on how to use it see the cgo documentation (go doc cmd/cgo).
-
-The second is the SWIG program, which is a general tool for
-interfacing between languages.  For information on SWIG see
-http://swig.org/.  When running go build, any file with a .swig
-extension will be passed to SWIG.  Any file with a .swigcxx extension
-will be passed to SWIG with the -c++ option.
-
-When either cgo or SWIG is used, go build will pass any .c, .m, .s,
-or .S files to the C compiler, and any .cc, .cpp, .cxx files to the C++
-compiler.  The CC or CXX environment variables may be set to determine
-the C or C++ compiler, respectively, to use.
-
-
-Description of build modes
-
-The 'go build' and 'go install' commands take a -buildmode argument which
-indicates which kind of object file is to be built. Currently supported values
-are:
-
-	-buildmode=archive
-		Build the listed non-main packages into .a files. Packages named
-		main are ignored.
-
-	-buildmode=c-archive
-		Build the listed main package, plus all packages it imports,
-		into a C archive file. The only callable symbols will be those
-		functions exported using a cgo //export comment. Requires
-		exactly one main package to be listed.
-
-	-buildmode=c-shared
-		Build the listed main packages, plus all packages that they
-		import, into C shared libraries. The only callable symbols will
-		be those functions exported using a cgo //export comment.
-		Non-main packages are ignored.
-
-	-buildmode=default
-		Listed main packages are built into executables and listed
-		non-main packages are built into .a files (the default
-		behavior).
-
-	-buildmode=shared
-		Combine all the listed non-main packages into a single shared
-		library that will be used when building with the -linkshared
-		option. Packages named main are ignored.
-
-	-buildmode=exe
-		Build the listed main packages and everything they import into
-		executables. Packages not named main are ignored.
-
-	-buildmode=pie
-		Build the listed main packages and everything they import into
-		position independent executables (PIE). Packages not named
-		main are ignored.
-
-
-File types
-
-The go command examines the contents of a restricted set of files
-in each directory. It identifies which files to examine based on
-the extension of the file name. These extensions are:
-
-	.go
-		Go source files.
-	.c, .h
-		C source files.
-		If the package uses cgo or SWIG, these will be compiled with the
-		OS-native compiler (typically gcc); otherwise they will
-		trigger an error.
-	.cc, .cpp, .cxx, .hh, .hpp, .hxx
-		C++ source files. Only useful with cgo or SWIG, and always
-		compiled with the OS-native compiler.
-	.m
-		Objective-C source files. Only useful with cgo, and always
-		compiled with the OS-native compiler.
-	.s, .S
-		Assembler source files.
-		If the package uses cgo or SWIG, these will be assembled with the
-		OS-native assembler (typically gcc (sic)); otherwise they
-		will be assembled with the Go assembler.
-	.swig, .swigcxx
-		SWIG definition files.
-	.syso
-		System object files.
-
-Files of each of these types except .syso may contain build
-constraints, but the go command stops scanning for build constraints
-at the first item in the file that is not a blank line or //-style
-line comment.
-
-
-GOPATH environment variable
-
-The Go path is used to resolve import statements.
-It is implemented by and documented in the go/build package.
-
-The GOPATH environment variable lists places to look for Go code.
-On Unix, the value is a colon-separated string.
-On Windows, the value is a semicolon-separated string.
-On Plan 9, the value is a list.
-
-GOPATH must be set to get, build and install packages outside the
-standard Go tree.
-
-Each directory listed in GOPATH must have a prescribed structure:
-
-The src directory holds source code.  The path below src
-determines the import path or executable name.
-
-The pkg directory holds installed package objects.
-As in the Go tree, each target operating system and
-architecture pair has its own subdirectory of pkg
-(pkg/GOOS_GOARCH).
-
-If DIR is a directory listed in the GOPATH, a package with
-source in DIR/src/foo/bar can be imported as "foo/bar" and
-has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a".
-
-The bin directory holds compiled commands.
-Each command is named for its source directory, but only
-the final element, not the entire path.  That is, the
-command with source in DIR/src/foo/quux is installed into
-DIR/bin/quux, not DIR/bin/foo/quux.  The "foo/" prefix is stripped
-so that you can add DIR/bin to your PATH to get at the
-installed commands.  If the GOBIN environment variable is
-set, commands are installed to the directory it names instead
-of DIR/bin. GOBIN must be an absolute path.
-
-Here's an example directory layout:
-
-    GOPATH=/home/user/gocode
-
-    /home/user/gocode/
-        src/
-            foo/
-                bar/               (go code in package bar)
-                    x.go
-                quux/              (go code in package main)
-                    y.go
-        bin/
-            quux                   (installed command)
-        pkg/
-            linux_amd64/
-                foo/
-                    bar.a          (installed package object)
-
-Go searches each directory listed in GOPATH to find source code,
-but new packages are always downloaded into the first directory
-in the list.
-
-See https://golang.org/doc/code.html for an example.
-
-Internal Directories
-
-Code in or below a directory named "internal" is importable only
-by code in the directory tree rooted at the parent of "internal".
-Here's an extended version of the directory layout above:
-
-    /home/user/gocode/
-        src/
-            crash/
-                bang/              (go code in package bang)
-                    b.go
-            foo/                   (go code in package foo)
-                f.go
-                bar/               (go code in package bar)
-                    x.go
-                internal/
-                    baz/           (go code in package baz)
-                        z.go
-                quux/              (go code in package main)
-                    y.go
-
-
-The code in z.go is imported as "foo/internal/baz", but that
-import statement can only appear in source files in the subtree
-rooted at foo. The source files foo/f.go, foo/bar/x.go, and
-foo/quux/y.go can all import "foo/internal/baz", but the source file
-crash/bang/b.go cannot.
-
-See https://golang.org/s/go14internal for details.
-
-Vendor Directories
-
-Go 1.6 includes support for using local copies of external dependencies
-to satisfy imports of those dependencies, often referred to as vendoring.
-
-Code below a directory named "vendor" is importable only
-by code in the directory tree rooted at the parent of "vendor",
-and only using an import path that omits the prefix up to and
-including the vendor element.
-
-Here's the example from the previous section,
-but with the "internal" directory renamed to "vendor"
-and a new foo/vendor/crash/bang directory added:
-
-    /home/user/gocode/
-        src/
-            crash/
-                bang/              (go code in package bang)
-                    b.go
-            foo/                   (go code in package foo)
-                f.go
-                bar/               (go code in package bar)
-                    x.go
-                vendor/
-                    crash/
-                        bang/      (go code in package bang)
-                            b.go
-                    baz/           (go code in package baz)
-                        z.go
-                quux/              (go code in package main)
-                    y.go
-
-The same visibility rules apply as for internal, but the code
-in z.go is imported as "baz", not as "foo/vendor/baz".
-
-Code in vendor directories deeper in the source tree shadows
-code in higher directories. Within the subtree rooted at foo, an import
-of "crash/bang" resolves to "foo/vendor/crash/bang", not the
-top-level "crash/bang".
-
-Code in vendor directories is not subject to import path
-checking (see 'go help importpath').
-
-When 'go get' checks out or updates a git repository, it now also
-updates submodules.
-
-Vendor directories do not affect the placement of new repositories
-being checked out for the first time by 'go get': those are always
-placed in the main GOPATH, never in a vendor subtree.
-
-In Go 1.5, as an experiment, setting the environment variable
-GO15VENDOREXPERIMENT=1 enabled these features.
-As of Go 1.6 they are on by default. To turn them off, set
-GO15VENDOREXPERIMENT=0. In Go 1.7, the environment
-variable will stop having any effect.
-
-See https://golang.org/s/go15vendor for details.
-
-
-Environment variables
-
-The go command, and the tools it invokes, examine a few different
-environment variables. For many of these, you can see the default
-value of on your system by running 'go env NAME', where NAME is the
-name of the variable.
-
-General-purpose environment variables:
-
-	GCCGO
-		The gccgo command to run for 'go build -compiler=gccgo'.
-	GOARCH
-		The architecture, or processor, for which to compile code.
-		Examples are amd64, 386, arm, ppc64.
-	GOBIN
-		The directory where 'go install' will install a command.
-	GOOS
-		The operating system for which to compile code.
-		Examples are linux, darwin, windows, netbsd.
-	GOPATH
-		See 'go help gopath'.
-	GORACE
-		Options for the race detector.
-		See https://golang.org/doc/articles/race_detector.html.
-	GOROOT
-		The root of the go tree.
-
-Environment variables for use with cgo:
-
-	CC
-		The command to use to compile C code.
-	CGO_ENABLED
-		Whether the cgo command is supported.  Either 0 or 1.
-	CGO_CFLAGS
-		Flags that cgo will pass to the compiler when compiling
-		C code.
-	CGO_CPPFLAGS
-		Flags that cgo will pass to the compiler when compiling
-		C or C++ code.
-	CGO_CXXFLAGS
-		Flags that cgo will pass to the compiler when compiling
-		C++ code.
-	CGO_LDFLAGS
-		Flags that cgo will pass to the compiler when linking.
-	CXX
-		The command to use to compile C++ code.
-
-Architecture-specific environment variables:
-
-	GOARM
-		For GOARCH=arm, the ARM architecture for which to compile.
-		Valid values are 5, 6, 7.
-	GO386
-		For GOARCH=386, the floating point instruction set.
-		Valid values are 387, sse2.
-
-Special-purpose environment variables:
-
-	GOROOT_FINAL
-		The root of the installed Go tree, when it is
-		installed in a location other than where it is built.
-		File names in stack traces are rewritten from GOROOT to
-		GOROOT_FINAL.
-	GO15VENDOREXPERIMENT
-		Set to 0 to disable vendoring semantics.
-	GO_EXTLINK_ENABLED
-		Whether the linker should use external linking mode
-		when using -linkmode=auto with code that uses cgo.
-		Set to 0 to disable external linking mode, 1 to enable it.
-
-
-Import path syntax
-
-An import path (see 'go help packages') denotes a package
-stored in the local file system.  In general, an import path denotes
-either a standard package (such as "unicode/utf8") or a package
-found in one of the work spaces (see 'go help gopath').
-
-Relative import paths
-
-An import path beginning with ./ or ../ is called a relative path.
-The toolchain supports relative import paths as a shortcut in two ways.
-
-First, a relative path can be used as a shorthand on the command line.
-If you are working in the directory containing the code imported as
-"unicode" and want to run the tests for "unicode/utf8", you can type
-"go test ./utf8" instead of needing to specify the full path.
-Similarly, in the reverse situation, "go test .." will test "unicode" from
-the "unicode/utf8" directory. Relative patterns are also allowed, like
-"go test ./..." to test all subdirectories. See 'go help packages' for details
-on the pattern syntax.
-
-Second, if you are compiling a Go program not in a work space,
-you can use a relative path in an import statement in that program
-to refer to nearby code also not in a work space.
-This makes it easy to experiment with small multipackage programs
-outside of the usual work spaces, but such programs cannot be
-installed with "go install" (there is no work space in which to install them),
-so they are rebuilt from scratch each time they are built.
-To avoid ambiguity, Go programs cannot use relative import paths
-within a work space.
-
-Remote import paths
-
-Certain import paths also
-describe how to obtain the source code for the package using
-a revision control system.
-
-A few common code hosting sites have special syntax:
-
-	Bitbucket (Git, Mercurial)
-
-		import "bitbucket.org/user/project"
-		import "bitbucket.org/user/project/sub/directory"
-
-	GitHub (Git)
-
-		import "github.com/user/project"
-		import "github.com/user/project/sub/directory"
-
-	Google Code Project Hosting (Git, Mercurial, Subversion)
-
-		import "code.google.com/p/project"
-		import "code.google.com/p/project/sub/directory"
-
-		import "code.google.com/p/project.subrepository"
-		import "code.google.com/p/project.subrepository/sub/directory"
-
-	Launchpad (Bazaar)
-
-		import "launchpad.net/project"
-		import "launchpad.net/project/series"
-		import "launchpad.net/project/series/sub/directory"
-
-		import "launchpad.net/~user/project/branch"
-		import "launchpad.net/~user/project/branch/sub/directory"
-
-	IBM DevOps Services (Git)
-
-		import "hub.jazz.net/git/user/project"
-		import "hub.jazz.net/git/user/project/sub/directory"
-
-For code hosted on other servers, import paths may either be qualified
-with the version control type, or the go tool can dynamically fetch
-the import path over https/http and discover where the code resides
-from a <meta> tag in the HTML.
-
-To declare the code location, an import path of the form
-
-	repository.vcs/path
-
-specifies the given repository, with or without the .vcs suffix,
-using the named version control system, and then the path inside
-that repository.  The supported version control systems are:
-
-	Bazaar      .bzr
-	Git         .git
-	Mercurial   .hg
-	Subversion  .svn
-
-For example,
-
-	import "example.org/user/foo.hg"
-
-denotes the root directory of the Mercurial repository at
-example.org/user/foo or foo.hg, and
-
-	import "example.org/repo.git/foo/bar"
-
-denotes the foo/bar directory of the Git repository at
-example.org/repo or repo.git.
-
-When a version control system supports multiple protocols,
-each is tried in turn when downloading.  For example, a Git
-download tries https://, then git+ssh://.
-
-If the import path is not a known code hosting site and also lacks a
-version control qualifier, the go tool attempts to fetch the import
-over https/http and looks for a <meta> tag in the document's HTML
-<head>.
-
-The meta tag has the form:
-
-	<meta name="go-import" content="import-prefix vcs repo-root">
-
-The import-prefix is the import path corresponding to the repository
-root. It must be a prefix or an exact match of the package being
-fetched with "go get". If it's not an exact match, another http
-request is made at the prefix to verify the <meta> tags match.
-
-The meta tag should appear as early in the file as possible.
-In particular, it should appear before any raw JavaScript or CSS,
-to avoid confusing the go command's restricted parser.
-
-The vcs is one of "git", "hg", "svn", etc,
-
-The repo-root is the root of the version control system
-containing a scheme and not containing a .vcs qualifier.
-
-For example,
-
-	import "example.org/pkg/foo"
-
-will result in the following requests:
-
-	https://example.org/pkg/foo?go-get=1 (preferred)
-	http://example.org/pkg/foo?go-get=1  (fallback, only with -insecure)
-
-If that page contains the meta tag
-
-	<meta name="go-import" content="example.org git https://code.org/r/p/exproj">
-
-the go tool will verify that https://example.org/?go-get=1 contains the
-same meta tag and then git clone https://code.org/r/p/exproj into
-GOPATH/src/example.org.
-
-New downloaded packages are written to the first directory
-listed in the GOPATH environment variable (see 'go help gopath').
-
-The go command attempts to download the version of the
-package appropriate for the Go release being used.
-Run 'go help get' for more.
-
-Import path checking
-
-When the custom import path feature described above redirects to a
-known code hosting site, each of the resulting packages has two possible
-import paths, using the custom domain or the known hosting site.
-
-A package statement is said to have an "import comment" if it is immediately
-followed (before the next newline) by a comment of one of these two forms:
-
-	package math // import "path"
-	package math /* import "path" * /
-
-The go command will refuse to install a package with an import comment
-unless it is being referred to by that import path. In this way, import comments
-let package authors make sure the custom import path is used and not a
-direct path to the underlying code hosting site.
-
-If vendoring is enabled (see 'go help gopath'), then import path checking is
-disabled for code found within vendor trees. This makes it possible to copy
-code into alternate locations in vendor trees without needing to update import
-comments.
-
-See https://golang.org/s/go14customimport for details.
-
-
-Description of package lists
-
-Many commands apply to a set of packages:
-
-	go action [packages]
-
-Usually, [packages] is a list of import paths.
-
-An import path that is a rooted path or that begins with
-a . or .. element is interpreted as a file system path and
-denotes the package in that directory.
-
-Otherwise, the import path P denotes the package found in
-the directory DIR/src/P for some DIR listed in the GOPATH
-environment variable (see 'go help gopath').
-
-If no import paths are given, the action applies to the
-package in the current directory.
-
-There are four reserved names for paths that should not be used
-for packages to be built with the go tool:
-
-- "main" denotes the top-level package in a stand-alone executable.
-
-- "all" expands to all package directories found in all the GOPATH
-trees. For example, 'go list all' lists all the packages on the local
-system.
-
-- "std" is like all but expands to just the packages in the standard
-Go library.
-
-- "cmd" expands to the Go repository's commands and their
-internal libraries.
-
-An import path is a pattern if it includes one or more "..." wildcards,
-each of which can match any string, including the empty string and
-strings containing slashes.  Such a pattern expands to all package
-directories found in the GOPATH trees with names matching the
-patterns.  As a special case, x/... matches x as well as x's subdirectories.
-For example, net/... expands to net and packages in its subdirectories.
-
-An import path can also name a package to be downloaded from
-a remote repository.  Run 'go help importpath' for details.
-
-Every package in a program must have a unique import path.
-By convention, this is arranged by starting each path with a
-unique prefix that belongs to you.  For example, paths used
-internally at Google all begin with 'google', and paths
-denoting remote repositories begin with the path to the code,
-such as 'github.com/user/repo'.
-
-Packages in a program need not have unique package names,
-but there are two reserved package names with special meaning.
-The name main indicates a command, not a library.
-Commands are built into binaries and cannot be imported.
-The name documentation indicates documentation for
-a non-Go program in the directory. Files in package documentation
-are ignored by the go command.
-
-As a special case, if the package list is a list of .go files from a
-single directory, the command is applied to a single synthesized
-package made up of exactly those files, ignoring any build constraints
-in those files and ignoring any other files in the directory.
-
-Directory and file names that begin with "." or "_" are ignored
-by the go tool, as are directories named "testdata".
-
-
-Description of testing flags
-
-The 'go test' command takes both flags that apply to 'go test' itself
-and flags that apply to the resulting test binary.
-
-Several of the flags control profiling and write an execution profile
-suitable for "go tool pprof"; run "go tool pprof -h" for more
-information.  The --alloc_space, --alloc_objects, and --show_bytes
-options of pprof control how the information is presented.
-
-The following flags are recognized by the 'go test' command and
-control the execution of any test:
-
-	-bench regexp
-	    Run benchmarks matching the regular expression.
-	    By default, no benchmarks run. To run all benchmarks,
-	    use '-bench .' or '-bench=.'.
-
-	-benchmem
-	    Print memory allocation statistics for benchmarks.
-
-	-benchtime t
-	    Run enough iterations of each benchmark to take t, specified
-	    as a time.Duration (for example, -benchtime 1h30s).
-	    The default is 1 second (1s).
-
-	-blockprofile block.out
-	    Write a goroutine blocking profile to the specified file
-	    when all tests are complete.
-	    Writes test binary as -c would.
-
-	-blockprofilerate n
-	    Control the detail provided in goroutine blocking profiles by
-	    calling runtime.SetBlockProfileRate with n.
-	    See 'go doc runtime.SetBlockProfileRate'.
-	    The profiler aims to sample, on average, one blocking event every
-	    n nanoseconds the program spends blocked.  By default,
-	    if -test.blockprofile is set without this flag, all blocking events
-	    are recorded, equivalent to -test.blockprofilerate=1.
-
-	-count n
-	    Run each test and benchmark n times (default 1).
-	    If -cpu is set, run n times for each GOMAXPROCS value.
-	    Examples are always run once.
-
-	-cover
-	    Enable coverage analysis.
-
-	-covermode set,count,atomic
-	    Set the mode for coverage analysis for the package[s]
-	    being tested. The default is "set" unless -race is enabled,
-	    in which case it is "atomic".
-	    The values:
-		set: bool: does this statement run?
-		count: int: how many times does this statement run?
-		atomic: int: count, but correct in multithreaded tests;
-			significantly more expensive.
-	    Sets -cover.
-
-	-coverpkg pkg1,pkg2,pkg3
-	    Apply coverage analysis in each test to the given list of packages.
-	    The default is for each test to analyze only the package being tested.
-	    Packages are specified as import paths.
-	    Sets -cover.
-
-	-coverprofile cover.out
-	    Write a coverage profile to the file after all tests have passed.
-	    Sets -cover.
-
-	-cpu 1,2,4
-	    Specify a list of GOMAXPROCS values for which the tests or
-	    benchmarks should be executed.  The default is the current value
-	    of GOMAXPROCS.
-
-	-cpuprofile cpu.out
-	    Write a CPU profile to the specified file before exiting.
-	    Writes test binary as -c would.
-
-	-memprofile mem.out
-	    Write a memory profile to the file after all tests have passed.
-	    Writes test binary as -c would.
-
-	-memprofilerate n
-	    Enable more precise (and expensive) memory profiles by setting
-	    runtime.MemProfileRate.  See 'go doc runtime.MemProfileRate'.
-	    To profile all memory allocations, use -test.memprofilerate=1
-	    and pass --alloc_space flag to the pprof tool.
-
-	-outputdir directory
-	    Place output files from profiling in the specified directory,
-	    by default the directory in which "go test" is running.
-
-	-parallel n
-	    Allow parallel execution of test functions that call t.Parallel.
-	    The value of this flag is the maximum number of tests to run
-	    simultaneously; by default, it is set to the value of GOMAXPROCS.
-	    Note that -parallel only applies within a single test binary.
-	    The 'go test' command may run tests for different packages
-	    in parallel as well, according to the setting of the -p flag
-	    (see 'go help build').
-
-	-run regexp
-	    Run only those tests and examples matching the regular
-	    expression.
-
-	-short
-	    Tell long-running tests to shorten their run time.
-	    It is off by default but set during all.bash so that installing
-	    the Go tree can run a sanity check but not spend time running
-	    exhaustive tests.
-
-	-timeout t
-	    If a test runs longer than t, panic.
-	    The default is 10 minutes (10m).
-
-	-trace trace.out
-	    Write an execution trace to the specified file before exiting.
-	    Writes test binary as -c would.
-
-	-v
-	    Verbose output: log all tests as they are run. Also print all
-	    text from Log and Logf calls even if the test succeeds.
-
-Each of these flags is also recognized with an optional 'test.' prefix,
-as in -test.v. When invoking the generated test binary (the result of
-'go test -c') directly, however, the prefix is mandatory.
-
-The 'go test' command rewrites or removes recognized flags,
-as appropriate, both before and after the optional package list,
-before invoking the test binary.
-
-For instance, the command
-
-	go test -v -myflag testdata -cpuprofile=prof.out -x
-
-will compile the test binary and then run it as
-
-	pkg.test -test.v -myflag testdata -test.cpuprofile=prof.out
-
-(The -x flag is removed because it applies only to the go command's
-execution, not to the test itself.)
-
-The test flags that generate profiles (other than for coverage) also
-leave the test binary in pkg.test for use when analyzing the profiles.
-
-When 'go test' runs a test binary, it does so from within the
-corresponding package's source code directory. Depending on the test,
-it may be necessary to do the same when invoking a generated test
-binary directly.
-
-The command-line package list, if present, must appear before any
-flag not known to the go test command. Continuing the example above,
-the package list would have to appear before -myflag, but could appear
-on either side of -v.
-
-To keep an argument for a test binary from being interpreted as a
-known flag or a package name, use -args (see 'go help test') which
-passes the remainder of the command line through to the test binary
-uninterpreted and unaltered.
-
-For instance, the command
-
-	go test -v -args -x -v
-
-will compile the test binary and then run it as
-
-	pkg.test -test.v -x -v
-
-Similarly,
-
-	go test -args math
-
-will compile the test binary and then run it as
-
-	pkg.test math
-
-In the first example, the -x and the second -v are passed through to the
-test binary unchanged and with no effect on the go command itself.
-In the second example, the argument math is passed through to the test
-binary, instead of being interpreted as the package list.
-
-
-Description of testing functions
-
-The 'go test' command expects to find test, benchmark, and example functions
-in the "*_test.go" files corresponding to the package under test.
-
-A test function is one named TestXXX (where XXX is any alphanumeric string
-not starting with a lower case letter) and should have the signature,
-
-	func TestXXX(t *testing.T) { ... }
-
-A benchmark function is one named BenchmarkXXX and should have the signature,
-
-	func BenchmarkXXX(b *testing.B) { ... }
-
-An example function is similar to a test function but, instead of using
-*testing.T to report success or failure, prints output to os.Stdout.
-That output is compared against the function's "Output:" comment, which
-must be the last comment in the function body (see example below). An
-example with no such comment, or with no text after "Output:" is compiled
-but not executed.
-
-Godoc displays the body of ExampleXXX to demonstrate the use
-of the function, constant, or variable XXX.  An example of a method M with
-receiver type T or *T is named ExampleT_M.  There may be multiple examples
-for a given function, constant, or variable, distinguished by a trailing _xxx,
-where xxx is a suffix not beginning with an upper case letter.
-
-Here is an example of an example:
-
-	func ExamplePrintln() {
-		Println("The output of\nthis example.")
-		// Output: The output of
-		// this example.
-	}
-
-The entire test file is presented as the example when it contains a single
-example function, at least one other function, type, variable, or constant
-declaration, and no test or benchmark functions.
-
-See the documentation of the testing package for more information.
-
-
-*/
+// Go is a tool for managing Go source code.
+//
+// Usage:
+//
+// 	go command [arguments]
+//
+// The commands are:
+//
+// 	build       compile packages and dependencies
+// 	clean       remove object files
+// 	doc         show documentation for package or symbol
+// 	env         print Go environment information
+// 	fix         run go tool fix on packages
+// 	fmt         run gofmt on package sources
+// 	generate    generate Go files by processing source
+// 	get         download and install packages and dependencies
+// 	install     compile and install packages and dependencies
+// 	list        list packages
+// 	run         compile and run Go program
+// 	test        test packages
+// 	tool        run specified go tool
+// 	version     print Go version
+// 	vet         run go tool vet on packages
+//
+// Use "go help [command]" for more information about a command.
+//
+// Additional help topics:
+//
+// 	c           calling between Go and C
+// 	buildmode   description of build modes
+// 	filetype    file types
+// 	gopath      GOPATH environment variable
+// 	environment environment variables
+// 	importpath  import path syntax
+// 	packages    description of package lists
+// 	testflag    description of testing flags
+// 	testfunc    description of testing functions
+//
+// Use "go help [topic]" for more information about that topic.
+//
+//
+// Compile packages and dependencies
+//
+// Usage:
+//
+// 	go build [-o output] [-i] [build flags] [packages]
+//
+// Build compiles the packages named by the import paths,
+// along with their dependencies, but it does not install the results.
+//
+// If the arguments to build are a list of .go files, build treats
+// them as a list of source files specifying a single package.
+//
+// When compiling a single main package, build writes
+// the resulting executable to an output file named after
+// the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe')
+// or the source code directory ('go build unix/sam' writes 'sam' or 'sam.exe').
+// The '.exe' suffix is added when writing a Windows executable.
+//
+// When compiling multiple packages or a single non-main package,
+// build compiles the packages but discards the resulting object,
+// serving only as a check that the packages can be built.
+//
+// When compiling packages, build ignores files that end in '_test.go'.
+//
+// The -o flag, only allowed when compiling a single package,
+// forces build to write the resulting executable or object
+// to the named output file, instead of the default behavior described
+// in the last two paragraphs.
+//
+// The -i flag installs the packages that are dependencies of the target.
+//
+// The build flags are shared by the build, clean, get, install, list, run,
+// and test commands:
+//
+// 	-a
+// 		force rebuilding of packages that are already up-to-date.
+// 	-n
+// 		print the commands but do not run them.
+// 	-p n
+// 		the number of programs, such as build commands or
+// 		test binaries, that can be run in parallel.
+// 		The default is the number of CPUs available.
+// 	-race
+// 		enable data race detection.
+// 		Supported only on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64.
+// 	-msan
+// 		enable interoperation with memory sanitizer.
+// 		Supported only on linux/amd64,
+// 		and only with Clang/LLVM as the host C compiler.
+// 	-v
+// 		print the names of packages as they are compiled.
+// 	-work
+// 		print the name of the temporary work directory and
+// 		do not delete it when exiting.
+// 	-x
+// 		print the commands.
+//
+// 	-asmflags 'flag list'
+// 		arguments to pass on each go tool asm invocation.
+// 	-buildmode mode
+// 		build mode to use. See 'go help buildmode' for more.
+// 	-compiler name
+// 		name of compiler to use, as in runtime.Compiler (gccgo or gc).
+// 	-gccgoflags 'arg list'
+// 		arguments to pass on each gccgo compiler/linker invocation.
+// 	-gcflags 'arg list'
+// 		arguments to pass on each go tool compile invocation.
+// 	-installsuffix suffix
+// 		a suffix to use in the name of the package installation directory,
+// 		in order to keep output separate from default builds.
+// 		If using the -race flag, the install suffix is automatically set to race
+// 		or, if set explicitly, has _race appended to it.  Likewise for the -msan
+// 		flag.  Using a -buildmode option that requires non-default compile flags
+// 		has a similar effect.
+// 	-ldflags 'flag list'
+// 		arguments to pass on each go tool link invocation.
+// 	-linkshared
+// 		link against shared libraries previously created with
+// 		-buildmode=shared.
+// 	-pkgdir dir
+// 		install and load all packages from dir instead of the usual locations.
+// 		For example, when building with a non-standard configuration,
+// 		use -pkgdir to keep generated packages in a separate location.
+// 	-tags 'tag list'
+// 		a list of build tags to consider satisfied during the build.
+// 		For more information about build tags, see the description of
+// 		build constraints in the documentation for the go/build package.
+// 	-toolexec 'cmd args'
+// 		a program to use to invoke toolchain programs like vet and asm.
+// 		For example, instead of running asm, the go command will run
+// 		'cmd args /path/to/asm <arguments for asm>'.
+//
+// The list flags accept a space-separated list of strings. To embed spaces
+// in an element in the list, surround it with either single or double quotes.
+//
+// For more about specifying packages, see 'go help packages'.
+// For more about where packages and binaries are installed,
+// run 'go help gopath'.
+// For more about calling between Go and C/C++, run 'go help c'.
+//
+// Note: Build adheres to certain conventions such as those described
+// by 'go help gopath'. Not all projects can follow these conventions,
+// however. Installations that have their own conventions or that use
+// a separate software build system may choose to use lower-level
+// invocations such as 'go tool compile' and 'go tool link' to avoid
+// some of the overheads and design decisions of the build tool.
+//
+// See also: go install, go get, go clean.
+//
+//
+// Remove object files
+//
+// Usage:
+//
+// 	go clean [-i] [-r] [-n] [-x] [build flags] [packages]
+//
+// Clean removes object files from package source directories.
+// The go command builds most objects in a temporary directory,
+// so go clean is mainly concerned with object files left by other
+// tools or by manual invocations of go build.
+//
+// Specifically, clean removes the following files from each of the
+// source directories corresponding to the import paths:
+//
+// 	_obj/            old object directory, left from Makefiles
+// 	_test/           old test directory, left from Makefiles
+// 	_testmain.go     old gotest file, left from Makefiles
+// 	test.out         old test log, left from Makefiles
+// 	build.out        old test log, left from Makefiles
+// 	*.[568ao]        object files, left from Makefiles
+//
+// 	DIR(.exe)        from go build
+// 	DIR.test(.exe)   from go test -c
+// 	MAINFILE(.exe)   from go build MAINFILE.go
+// 	*.so             from SWIG
+//
+// In the list, DIR represents the final path element of the
+// directory, and MAINFILE is the base name of any Go source
+// file in the directory that is not included when building
+// the package.
+//
+// The -i flag causes clean to remove the corresponding installed
+// archive or binary (what 'go install' would create).
+//
+// The -n flag causes clean to print the remove commands it would execute,
+// but not run them.
+//
+// The -r flag causes clean to be applied recursively to all the
+// dependencies of the packages named by the import paths.
+//
+// The -x flag causes clean to print remove commands as it executes them.
+//
+// For more about build flags, see 'go help build'.
+//
+// For more about specifying packages, see 'go help packages'.
+//
+//
+// Show documentation for package or symbol
+//
+// Usage:
+//
+// 	go doc [-u] [-c] [package|[package.]symbol[.method]]
+//
+// Doc prints the documentation comments associated with the item identified by its
+// arguments (a package, const, func, type, var, or method) followed by a one-line
+// summary of each of the first-level items "under" that item (package-level
+// declarations for a package, methods for a type, etc.).
+//
+// Doc accepts zero, one, or two arguments.
+//
+// Given no arguments, that is, when run as
+//
+// 	go doc
+//
+// it prints the package documentation for the package in the current directory.
+// If the package is a command (package main), the exported symbols of the package
+// are elided from the presentation unless the -cmd flag is provided.
+//
+// When run with one argument, the argument is treated as a Go-syntax-like
+// representation of the item to be documented. What the argument selects depends
+// on what is installed in GOROOT and GOPATH, as well as the form of the argument,
+// which is schematically one of these:
+//
+// 	go doc <pkg>
+// 	go doc <sym>[.<method>]
+// 	go doc [<pkg>.]<sym>[.<method>]
+// 	go doc [<pkg>.][<sym>.]<method>
+//
+// The first item in this list matched by the argument is the one whose documentation
+// is printed. (See the examples below.) However, if the argument starts with a capital
+// letter it is assumed to identify a symbol or method in the current directory.
+//
+// For packages, the order of scanning is determined lexically in breadth-first order.
+// That is, the package presented is the one that matches the search and is nearest
+// the root and lexically first at its level of the hierarchy.  The GOROOT tree is
+// always scanned in its entirety before GOPATH.
+//
+// If there is no package specified or matched, the package in the current
+// directory is selected, so "go doc Foo" shows the documentation for symbol Foo in
+// the current package.
+//
+// The package path must be either a qualified path or a proper suffix of a
+// path. The go tool's usual package mechanism does not apply: package path
+// elements like . and ... are not implemented by go doc.
+//
+// When run with two arguments, the first must be a full package path (not just a
+// suffix), and the second is a symbol or symbol and method; this is similar to the
+// syntax accepted by godoc:
+//
+// 	go doc <pkg> <sym>[.<method>]
+//
+// In all forms, when matching symbols, lower-case letters in the argument match
+// either case but upper-case letters match exactly. This means that there may be
+// multiple matches of a lower-case argument in a package if different symbols have
+// different cases. If this occurs, documentation for all matches is printed.
+//
+// Examples:
+// 	go doc
+// 		Show documentation for current package.
+// 	go doc Foo
+// 		Show documentation for Foo in the current package.
+// 		(Foo starts with a capital letter so it cannot match
+// 		a package path.)
+// 	go doc encoding/json
+// 		Show documentation for the encoding/json package.
+// 	go doc json
+// 		Shorthand for encoding/json.
+// 	go doc json.Number (or go doc json.number)
+// 		Show documentation and method summary for json.Number.
+// 	go doc json.Number.Int64 (or go doc json.number.int64)
+// 		Show documentation for json.Number's Int64 method.
+// 	go doc cmd/doc
+// 		Show package docs for the doc command.
+// 	go doc -cmd cmd/doc
+// 		Show package docs and exported symbols within the doc command.
+// 	go doc template.new
+// 		Show documentation for html/template's New function.
+// 		(html/template is lexically before text/template)
+// 	go doc text/template.new # One argument
+// 		Show documentation for text/template's New function.
+// 	go doc text/template new # Two arguments
+// 		Show documentation for text/template's New function.
+//
+// 	At least in the current tree, these invocations all print the
+// 	documentation for json.Decoder's Decode method:
+//
+// 	go doc json.Decoder.Decode
+// 	go doc json.decoder.decode
+// 	go doc json.decode
+// 	cd go/src/encoding/json; go doc decode
+//
+// Flags:
+// 	-c
+// 		Respect case when matching symbols.
+// 	-cmd
+// 		Treat a command (package main) like a regular package.
+// 		Otherwise package main's exported symbols are hidden
+// 		when showing the package's top-level documentation.
+// 	-u
+// 		Show documentation for unexported as well as exported
+// 		symbols and methods.
+//
+//
+// Print Go environment information
+//
+// Usage:
+//
+// 	go env [var ...]
+//
+// Env prints Go environment information.
+//
+// By default env prints information as a shell script
+// (on Windows, a batch file).  If one or more variable
+// names is given as arguments,  env prints the value of
+// each named variable on its own line.
+//
+//
+// Run go tool fix on packages
+//
+// Usage:
+//
+// 	go fix [packages]
+//
+// Fix runs the Go fix command on the packages named by the import paths.
+//
+// For more about fix, see 'go doc cmd/fix'.
+// For more about specifying packages, see 'go help packages'.
+//
+// To run fix with specific options, run 'go tool fix'.
+//
+// See also: go fmt, go vet.
+//
+//
+// Run gofmt on package sources
+//
+// Usage:
+//
+// 	go fmt [-n] [-x] [packages]
+//
+// Fmt runs the command 'gofmt -l -w' on the packages named
+// by the import paths.  It prints the names of the files that are modified.
+//
+// For more about gofmt, see 'go doc cmd/gofmt'.
+// For more about specifying packages, see 'go help packages'.
+//
+// The -n flag prints commands that would be executed.
+// The -x flag prints commands as they are executed.
+//
+// To run gofmt with specific options, run gofmt itself.
+//
+// See also: go fix, go vet.
+//
+//
+// Generate Go files by processing source
+//
+// Usage:
+//
+// 	go generate [-run regexp] [-n] [-v] [-x] [build flags] [file.go... | packages]
+//
+// Generate runs commands described by directives within existing
+// files. Those commands can run any process but the intent is to
+// create or update Go source files, for instance by running yacc.
+//
+// Go generate is never run automatically by go build, go get, go test,
+// and so on. It must be run explicitly.
+//
+// Go generate scans the file for directives, which are lines of
+// the form,
+//
+// 	//go:generate command argument...
+//
+// (note: no leading spaces and no space in "//go") where command
+// is the generator to be run, corresponding to an executable file
+// that can be run locally. It must either be in the shell path
+// (gofmt), a fully qualified path (/usr/you/bin/mytool), or a
+// command alias, described below.
+//
+// Note that go generate does not parse the file, so lines that look
+// like directives in comments or multiline strings will be treated
+// as directives.
+//
+// The arguments to the directive are space-separated tokens or
+// double-quoted strings passed to the generator as individual
+// arguments when it is run.
+//
+// Quoted strings use Go syntax and are evaluated before execution; a
+// quoted string appears as a single argument to the generator.
+//
+// Go generate sets several variables when it runs the generator:
+//
+// 	$GOARCH
+// 		The execution architecture (arm, amd64, etc.)
+// 	$GOOS
+// 		The execution operating system (linux, windows, etc.)
+// 	$GOFILE
+// 		The base name of the file.
+// 	$GOLINE
+// 		The line number of the directive in the source file.
+// 	$GOPACKAGE
+// 		The name of the package of the file containing the directive.
+// 	$DOLLAR
+// 		A dollar sign.
+//
+// Other than variable substitution and quoted-string evaluation, no
+// special processing such as "globbing" is performed on the command
+// line.
+//
+// As a last step before running the command, any invocations of any
+// environment variables with alphanumeric names, such as $GOFILE or
+// $HOME, are expanded throughout the command line. The syntax for
+// variable expansion is $NAME on all operating systems.  Due to the
+// order of evaluation, variables are expanded even inside quoted
+// strings. If the variable NAME is not set, $NAME expands to the
+// empty string.
+//
+// A directive of the form,
+//
+// 	//go:generate -command xxx args...
+//
+// specifies, for the remainder of this source file only, that the
+// string xxx represents the command identified by the arguments. This
+// can be used to create aliases or to handle multiword generators.
+// For example,
+//
+// 	//go:generate -command yacc go tool yacc
+//
+// specifies that the command "yacc" represents the generator
+// "go tool yacc".
+//
+// Generate processes packages in the order given on the command line,
+// one at a time. If the command line lists .go files, they are treated
+// as a single package. Within a package, generate processes the
+// source files in a package in file name order, one at a time. Within
+// a source file, generate runs generators in the order they appear
+// in the file, one at a time.
+//
+// If any generator returns an error exit status, "go generate" skips
+// all further processing for that package.
+//
+// The generator is run in the package's source directory.
+//
+// Go generate accepts one specific flag:
+//
+// 	-run=""
+// 		if non-empty, specifies a regular expression to select
+// 		directives whose full original source text (excluding
+// 		any trailing spaces and final newline) matches the
+// 		expression.
+//
+// It also accepts the standard build flags including -v, -n, and -x.
+// The -v flag prints the names of packages and files as they are
+// processed.
+// The -n flag prints commands that would be executed.
+// The -x flag prints commands as they are executed.
+//
+// For more about build flags, see 'go help build'.
+//
+// For more about specifying packages, see 'go help packages'.
+//
+//
+// Download and install packages and dependencies
+//
+// Usage:
+//
+// 	go get [-d] [-f] [-fix] [-insecure] [-t] [-u] [build flags] [packages]
+//
+// Get downloads the packages named by the import paths, along with their
+// dependencies. It then installs the named packages, like 'go install'.
+//
+// The -d flag instructs get to stop after downloading the packages; that is,
+// it instructs get not to install the packages.
+//
+// The -f flag, valid only when -u is set, forces get -u not to verify that
+// each package has been checked out from the source control repository
+// implied by its import path. This can be useful if the source is a local fork
+// of the original.
+//
+// The -fix flag instructs get to run the fix tool on the downloaded packages
+// before resolving dependencies or building the code.
+//
+// The -insecure flag permits fetching from repositories and resolving
+// custom domains using insecure schemes such as HTTP. Use with caution.
+//
+// The -t flag instructs get to also download the packages required to build
+// the tests for the specified packages.
+//
+// The -u flag instructs get to use the network to update the named packages
+// and their dependencies.  By default, get uses the network to check out
+// missing packages but does not use it to look for updates to existing packages.
+//
+// Get also accepts build flags to control the installation. See 'go help build'.
+//
+// When checking out a new package, get creates the target directory
+// GOPATH/src/<import-path>. If the GOPATH contains multiple entries,
+// get uses the first one. See 'go help gopath'.
+//
+// When checking out or updating a package, get looks for a branch or tag
+// that matches the locally installed version of Go. The most important
+// rule is that if the local installation is running version "go1", get
+// searches for a branch or tag named "go1". If no such version exists it
+// retrieves the most recent version of the package.
+//
+// When go get checks out or updates a Git repository,
+// it also updates any git submodules referenced by the repository.
+//
+// Get never checks out or updates code stored in vendor directories.
+//
+// For more about specifying packages, see 'go help packages'.
+//
+// For more about how 'go get' finds source code to
+// download, see 'go help importpath'.
+//
+// See also: go build, go install, go clean.
+//
+//
+// Compile and install packages and dependencies
+//
+// Usage:
+//
+// 	go install [build flags] [packages]
+//
+// Install compiles and installs the packages named by the import paths,
+// along with their dependencies.
+//
+// For more about the build flags, see 'go help build'.
+// For more about specifying packages, see 'go help packages'.
+//
+// See also: go build, go get, go clean.
+//
+//
+// List packages
+//
+// Usage:
+//
+// 	go list [-e] [-f format] [-json] [build flags] [packages]
+//
+// List lists the packages named by the import paths, one per line.
+//
+// The default output shows the package import path:
+//
+//     bytes
+//     encoding/json
+//     github.com/gorilla/mux
+//     golang.org/x/net/html
+//
+// The -f flag specifies an alternate format for the list, using the
+// syntax of package template.  The default output is equivalent to -f
+// '{{.ImportPath}}'. The struct being passed to the template is:
+//
+//     type Package struct {
+//         Dir           string // directory containing package sources
+//         ImportPath    string // import path of package in dir
+//         ImportComment string // path in import comment on package statement
+//         Name          string // package name
+//         Doc           string // package documentation string
+//         Target        string // install path
+//         Shlib         string // the shared library that contains this package (only set when -linkshared)
+//         Goroot        bool   // is this package in the Go root?
+//         Standard      bool   // is this package part of the standard Go library?
+//         Stale         bool   // would 'go install' do anything for this package?
+//         StaleReason   string // explanation for Stale==true
+//         Root          string // Go root or Go path dir containing this package
+//         ConflictDir   string // this directory shadows Dir in $GOPATH
+//         BinaryOnly    bool   // binary-only package: cannot be recompiled from sources
+//
+//         // Source files
+//         GoFiles        []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
+//         CgoFiles       []string // .go sources files that import "C"
+//         IgnoredGoFiles []string // .go sources ignored due to build constraints
+//         CFiles         []string // .c source files
+//         CXXFiles       []string // .cc, .cxx and .cpp source files
+//         MFiles         []string // .m source files
+//         HFiles         []string // .h, .hh, .hpp and .hxx source files
+//         FFiles         []string // .f, .F, .for and .f90 Fortran source files
+//         SFiles         []string // .s source files
+//         SwigFiles      []string // .swig files
+//         SwigCXXFiles   []string // .swigcxx files
+//         SysoFiles      []string // .syso object files to add to archive
+//
+//         // Cgo directives
+//         CgoCFLAGS    []string // cgo: flags for C compiler
+//         CgoCPPFLAGS  []string // cgo: flags for C preprocessor
+//         CgoCXXFLAGS  []string // cgo: flags for C++ compiler
+//         CgoFFLAGS    []string // cgo: flags for Fortran compiler
+//         CgoLDFLAGS   []string // cgo: flags for linker
+//         CgoPkgConfig []string // cgo: pkg-config names
+//
+//         // Dependency information
+//         Imports []string // import paths used by this package
+//         Deps    []string // all (recursively) imported dependencies
+//
+//         // Error information
+//         Incomplete bool            // this package or a dependency has an error
+//         Error      *PackageError   // error loading package
+//         DepsErrors []*PackageError // errors loading dependencies
+//
+//         TestGoFiles  []string // _test.go files in package
+//         TestImports  []string // imports from TestGoFiles
+//         XTestGoFiles []string // _test.go files outside package
+//         XTestImports []string // imports from XTestGoFiles
+//     }
+//
+// The error information, if any, is
+//
+//     type PackageError struct {
+//         ImportStack   []string // shortest path from package named on command line to this one
+//         Pos           string   // position of error (if present, file:line:col)
+//         Err           string   // the error itself
+//     }
+//
+// The template function "join" calls strings.Join.
+//
+// The template function "context" returns the build context, defined as:
+//
+// 	type Context struct {
+// 		GOARCH        string   // target architecture
+// 		GOOS          string   // target operating system
+// 		GOROOT        string   // Go root
+// 		GOPATH        string   // Go path
+// 		CgoEnabled    bool     // whether cgo can be used
+// 		UseAllFiles   bool     // use files regardless of +build lines, file names
+// 		Compiler      string   // compiler to assume when computing target paths
+// 		BuildTags     []string // build constraints to match in +build lines
+// 		ReleaseTags   []string // releases the current release is compatible with
+// 		InstallSuffix string   // suffix to use in the name of the install dir
+// 	}
+//
+// For more information about the meaning of these fields see the documentation
+// for the go/build package's Context type.
+//
+// The -json flag causes the package data to be printed in JSON format
+// instead of using the template format.
+//
+// The -e flag changes the handling of erroneous packages, those that
+// cannot be found or are malformed.  By default, the list command
+// prints an error to standard error for each erroneous package and
+// omits the packages from consideration during the usual printing.
+// With the -e flag, the list command never prints errors to standard
+// error and instead processes the erroneous packages with the usual
+// printing.  Erroneous packages will have a non-empty ImportPath and
+// a non-nil Error field; other information may or may not be missing
+// (zeroed).
+//
+// For more about build flags, see 'go help build'.
+//
+// For more about specifying packages, see 'go help packages'.
+//
+//
+// Compile and run Go program
+//
+// Usage:
+//
+// 	go run [build flags] [-exec xprog] gofiles... [arguments...]
+//
+// Run compiles and runs the main package comprising the named Go source files.
+// A Go source file is defined to be a file ending in a literal ".go" suffix.
+//
+// By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
+// If the -exec flag is given, 'go run' invokes the binary using xprog:
+// 	'xprog a.out arguments...'.
+// If the -exec flag is not given, GOOS or GOARCH is different from the system
+// default, and a program named go_$GOOS_$GOARCH_exec can be found
+// on the current search path, 'go run' invokes the binary using that program,
+// for example 'go_nacl_386_exec a.out arguments...'. This allows execution of
+// cross-compiled programs when a simulator or other execution method is
+// available.
+//
+// For more about build flags, see 'go help build'.
+//
+// See also: go build.
+//
+//
+// Test packages
+//
+// Usage:
+//
+// 	go test [build/test flags] [packages] [build/test flags & test binary flags]
+//
+// 'Go test' automates testing the packages named by the import paths.
+// It prints a summary of the test results in the format:
+//
+// 	ok   archive/tar   0.011s
+// 	FAIL archive/zip   0.022s
+// 	ok   compress/gzip 0.033s
+// 	...
+//
+// followed by detailed output for each failed package.
+//
+// 'Go test' recompiles each package along with any files with names matching
+// the file pattern "*_test.go".
+// Files whose names begin with "_" (including "_test.go") or "." are ignored.
+// These additional files can contain test functions, benchmark functions, and
+// example functions.  See 'go help testfunc' for more.
+// Each listed package causes the execution of a separate test binary.
+//
+// Test files that declare a package with the suffix "_test" will be compiled as a
+// separate package, and then linked and run with the main test binary.
+//
+// The go tool will ignore a directory named "testdata", making it available
+// to hold ancillary data needed by the tests.
+//
+// By default, go test needs no arguments.  It compiles and tests the package
+// with source in the current directory, including tests, and runs the tests.
+//
+// The package is built in a temporary directory so it does not interfere with the
+// non-test installation.
+//
+// In addition to the build flags, the flags handled by 'go test' itself are:
+//
+// 	-args
+// 	    Pass the remainder of the command line (everything after -args)
+// 	    to the test binary, uninterpreted and unchanged.
+// 	    Because this flag consumes the remainder of the command line,
+// 	    the package list (if present) must appear before this flag.
+//
+// 	-c
+// 	    Compile the test binary to pkg.test but do not run it
+// 	    (where pkg is the last element of the package's import path).
+// 	    The file name can be changed with the -o flag.
+//
+// 	-exec xprog
+// 	    Run the test binary using xprog. The behavior is the same as
+// 	    in 'go run'. See 'go help run' for details.
+//
+// 	-i
+// 	    Install packages that are dependencies of the test.
+// 	    Do not run the test.
+//
+// 	-o file
+// 	    Compile the test binary to the named file.
+// 	    The test still runs (unless -c or -i is specified).
+//
+// The test binary also accepts flags that control execution of the test; these
+// flags are also accessible by 'go test'. See 'go help testflag' for details.
+//
+// For more about build flags, see 'go help build'.
+// For more about specifying packages, see 'go help packages'.
+//
+// See also: go build, go vet.
+//
+//
+// Run specified go tool
+//
+// Usage:
+//
+// 	go tool [-n] command [args...]
+//
+// Tool runs the go tool command identified by the arguments.
+// With no arguments it prints the list of known tools.
+//
+// The -n flag causes tool to print the command that would be
+// executed but not execute it.
+//
+// For more about each tool command, see 'go tool command -h'.
+//
+//
+// Print Go version
+//
+// Usage:
+//
+// 	go version
+//
+// Version prints the Go version, as reported by runtime.Version.
+//
+//
+// Run go tool vet on packages
+//
+// Usage:
+//
+// 	go vet [-n] [-x] [build flags] [packages]
+//
+// Vet runs the Go vet command on the packages named by the import paths.
+//
+// For more about vet, see 'go doc cmd/vet'.
+// For more about specifying packages, see 'go help packages'.
+//
+// To run the vet tool with specific options, run 'go tool vet'.
+//
+// The -n flag prints commands that would be executed.
+// The -x flag prints commands as they are executed.
+//
+// For more about build flags, see 'go help build'.
+//
+// See also: go fmt, go fix.
+//
+//
+// Calling between Go and C
+//
+// There are two different ways to call between Go and C/C++ code.
+//
+// The first is the cgo tool, which is part of the Go distribution.  For
+// information on how to use it see the cgo documentation (go doc cmd/cgo).
+//
+// The second is the SWIG program, which is a general tool for
+// interfacing between languages.  For information on SWIG see
+// http://swig.org/.  When running go build, any file with a .swig
+// extension will be passed to SWIG.  Any file with a .swigcxx extension
+// will be passed to SWIG with the -c++ option.
+//
+// When either cgo or SWIG is used, go build will pass any .c, .m, .s,
+// or .S files to the C compiler, and any .cc, .cpp, .cxx files to the C++
+// compiler.  The CC or CXX environment variables may be set to determine
+// the C or C++ compiler, respectively, to use.
+//
+//
+// Description of build modes
+//
+// The 'go build' and 'go install' commands take a -buildmode argument which
+// indicates which kind of object file is to be built. Currently supported values
+// are:
+//
+// 	-buildmode=archive
+// 		Build the listed non-main packages into .a files. Packages named
+// 		main are ignored.
+//
+// 	-buildmode=c-archive
+// 		Build the listed main package, plus all packages it imports,
+// 		into a C archive file. The only callable symbols will be those
+// 		functions exported using a cgo //export comment. Requires
+// 		exactly one main package to be listed.
+//
+// 	-buildmode=c-shared
+// 		Build the listed main packages, plus all packages that they
+// 		import, into C shared libraries. The only callable symbols will
+// 		be those functions exported using a cgo //export comment.
+// 		Non-main packages are ignored.
+//
+// 	-buildmode=default
+// 		Listed main packages are built into executables and listed
+// 		non-main packages are built into .a files (the default
+// 		behavior).
+//
+// 	-buildmode=shared
+// 		Combine all the listed non-main packages into a single shared
+// 		library that will be used when building with the -linkshared
+// 		option. Packages named main are ignored.
+//
+// 	-buildmode=exe
+// 		Build the listed main packages and everything they import into
+// 		executables. Packages not named main are ignored.
+//
+// 	-buildmode=pie
+// 		Build the listed main packages and everything they import into
+// 		position independent executables (PIE). Packages not named
+// 		main are ignored.
+//
+//
+// File types
+//
+// The go command examines the contents of a restricted set of files
+// in each directory. It identifies which files to examine based on
+// the extension of the file name. These extensions are:
+//
+// 	.go
+// 		Go source files.
+// 	.c, .h
+// 		C source files.
+// 		If the package uses cgo or SWIG, these will be compiled with the
+// 		OS-native compiler (typically gcc); otherwise they will
+// 		trigger an error.
+// 	.cc, .cpp, .cxx, .hh, .hpp, .hxx
+// 		C++ source files. Only useful with cgo or SWIG, and always
+// 		compiled with the OS-native compiler.
+// 	.m
+// 		Objective-C source files. Only useful with cgo, and always
+// 		compiled with the OS-native compiler.
+// 	.s, .S
+// 		Assembler source files.
+// 		If the package uses cgo or SWIG, these will be assembled with the
+// 		OS-native assembler (typically gcc (sic)); otherwise they
+// 		will be assembled with the Go assembler.
+// 	.swig, .swigcxx
+// 		SWIG definition files.
+// 	.syso
+// 		System object files.
+//
+// Files of each of these types except .syso may contain build
+// constraints, but the go command stops scanning for build constraints
+// at the first item in the file that is not a blank line or //-style
+// line comment. See the go/build package documentation for
+// more details.
+//
+// Non-test Go source files can also include a //go:binary-only-package
+// comment, indicating that the package sources are included
+// for documentation only and must not be used to build the
+// package binary. This enables distribution of Go packages in
+// their compiled form alone. See the go/build package documentation
+// for more details.
+//
+//
+// GOPATH environment variable
+//
+// The Go path is used to resolve import statements.
+// It is implemented by and documented in the go/build package.
+//
+// The GOPATH environment variable lists places to look for Go code.
+// On Unix, the value is a colon-separated string.
+// On Windows, the value is a semicolon-separated string.
+// On Plan 9, the value is a list.
+//
+// GOPATH must be set to get, build and install packages outside the
+// standard Go tree.
+//
+// Each directory listed in GOPATH must have a prescribed structure:
+//
+// The src directory holds source code.  The path below src
+// determines the import path or executable name.
+//
+// The pkg directory holds installed package objects.
+// As in the Go tree, each target operating system and
+// architecture pair has its own subdirectory of pkg
+// (pkg/GOOS_GOARCH).
+//
+// If DIR is a directory listed in the GOPATH, a package with
+// source in DIR/src/foo/bar can be imported as "foo/bar" and
+// has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a".
+//
+// The bin directory holds compiled commands.
+// Each command is named for its source directory, but only
+// the final element, not the entire path.  That is, the
+// command with source in DIR/src/foo/quux is installed into
+// DIR/bin/quux, not DIR/bin/foo/quux.  The "foo/" prefix is stripped
+// so that you can add DIR/bin to your PATH to get at the
+// installed commands.  If the GOBIN environment variable is
+// set, commands are installed to the directory it names instead
+// of DIR/bin. GOBIN must be an absolute path.
+//
+// Here's an example directory layout:
+//
+//     GOPATH=/home/user/gocode
+//
+//     /home/user/gocode/
+//         src/
+//             foo/
+//                 bar/               (go code in package bar)
+//                     x.go
+//                 quux/              (go code in package main)
+//                     y.go
+//         bin/
+//             quux                   (installed command)
+//         pkg/
+//             linux_amd64/
+//                 foo/
+//                     bar.a          (installed package object)
+//
+// Go searches each directory listed in GOPATH to find source code,
+// but new packages are always downloaded into the first directory
+// in the list.
+//
+// See https://golang.org/doc/code.html for an example.
+//
+// Internal Directories
+//
+// Code in or below a directory named "internal" is importable only
+// by code in the directory tree rooted at the parent of "internal".
+// Here's an extended version of the directory layout above:
+//
+//     /home/user/gocode/
+//         src/
+//             crash/
+//                 bang/              (go code in package bang)
+//                     b.go
+//             foo/                   (go code in package foo)
+//                 f.go
+//                 bar/               (go code in package bar)
+//                     x.go
+//                 internal/
+//                     baz/           (go code in package baz)
+//                         z.go
+//                 quux/              (go code in package main)
+//                     y.go
+//
+//
+// The code in z.go is imported as "foo/internal/baz", but that
+// import statement can only appear in source files in the subtree
+// rooted at foo. The source files foo/f.go, foo/bar/x.go, and
+// foo/quux/y.go can all import "foo/internal/baz", but the source file
+// crash/bang/b.go cannot.
+//
+// See https://golang.org/s/go14internal for details.
+//
+// Vendor Directories
+//
+// Go 1.6 includes support for using local copies of external dependencies
+// to satisfy imports of those dependencies, often referred to as vendoring.
+//
+// Code below a directory named "vendor" is importable only
+// by code in the directory tree rooted at the parent of "vendor",
+// and only using an import path that omits the prefix up to and
+// including the vendor element.
+//
+// Here's the example from the previous section,
+// but with the "internal" directory renamed to "vendor"
+// and a new foo/vendor/crash/bang directory added:
+//
+//     /home/user/gocode/
+//         src/
+//             crash/
+//                 bang/              (go code in package bang)
+//                     b.go
+//             foo/                   (go code in package foo)
+//                 f.go
+//                 bar/               (go code in package bar)
+//                     x.go
+//                 vendor/
+//                     crash/
+//                         bang/      (go code in package bang)
+//                             b.go
+//                     baz/           (go code in package baz)
+//                         z.go
+//                 quux/              (go code in package main)
+//                     y.go
+//
+// The same visibility rules apply as for internal, but the code
+// in z.go is imported as "baz", not as "foo/vendor/baz".
+//
+// Code in vendor directories deeper in the source tree shadows
+// code in higher directories. Within the subtree rooted at foo, an import
+// of "crash/bang" resolves to "foo/vendor/crash/bang", not the
+// top-level "crash/bang".
+//
+// Code in vendor directories is not subject to import path
+// checking (see 'go help importpath').
+//
+// When 'go get' checks out or updates a git repository, it now also
+// updates submodules.
+//
+// Vendor directories do not affect the placement of new repositories
+// being checked out for the first time by 'go get': those are always
+// placed in the main GOPATH, never in a vendor subtree.
+//
+// See https://golang.org/s/go15vendor for details.
+//
+//
+// Environment variables
+//
+// The go command, and the tools it invokes, examine a few different
+// environment variables. For many of these, you can see the default
+// value of on your system by running 'go env NAME', where NAME is the
+// name of the variable.
+//
+// General-purpose environment variables:
+//
+// 	GCCGO
+// 		The gccgo command to run for 'go build -compiler=gccgo'.
+// 	GOARCH
+// 		The architecture, or processor, for which to compile code.
+// 		Examples are amd64, 386, arm, ppc64.
+// 	GOBIN
+// 		The directory where 'go install' will install a command.
+// 	GOOS
+// 		The operating system for which to compile code.
+// 		Examples are linux, darwin, windows, netbsd.
+// 	GOPATH
+// 		See 'go help gopath'.
+// 	GORACE
+// 		Options for the race detector.
+// 		See https://golang.org/doc/articles/race_detector.html.
+// 	GOROOT
+// 		The root of the go tree.
+//
+// Environment variables for use with cgo:
+//
+// 	CC
+// 		The command to use to compile C code.
+// 	CGO_ENABLED
+// 		Whether the cgo command is supported.  Either 0 or 1.
+// 	CGO_CFLAGS
+// 		Flags that cgo will pass to the compiler when compiling
+// 		C code.
+// 	CGO_CPPFLAGS
+// 		Flags that cgo will pass to the compiler when compiling
+// 		C or C++ code.
+// 	CGO_CXXFLAGS
+// 		Flags that cgo will pass to the compiler when compiling
+// 		C++ code.
+// 	CGO_LDFLAGS
+// 		Flags that cgo will pass to the compiler when linking.
+// 	CXX
+// 		The command to use to compile C++ code.
+//
+// Architecture-specific environment variables:
+//
+// 	GOARM
+// 		For GOARCH=arm, the ARM architecture for which to compile.
+// 		Valid values are 5, 6, 7.
+// 	GO386
+// 		For GOARCH=386, the floating point instruction set.
+// 		Valid values are 387, sse2.
+//
+// Special-purpose environment variables:
+//
+// 	GOROOT_FINAL
+// 		The root of the installed Go tree, when it is
+// 		installed in a location other than where it is built.
+// 		File names in stack traces are rewritten from GOROOT to
+// 		GOROOT_FINAL.
+// 	GO_EXTLINK_ENABLED
+// 		Whether the linker should use external linking mode
+// 		when using -linkmode=auto with code that uses cgo.
+// 		Set to 0 to disable external linking mode, 1 to enable it.
+//
+//
+// Import path syntax
+//
+// An import path (see 'go help packages') denotes a package
+// stored in the local file system.  In general, an import path denotes
+// either a standard package (such as "unicode/utf8") or a package
+// found in one of the work spaces (see 'go help gopath').
+//
+// Relative import paths
+//
+// An import path beginning with ./ or ../ is called a relative path.
+// The toolchain supports relative import paths as a shortcut in two ways.
+//
+// First, a relative path can be used as a shorthand on the command line.
+// If you are working in the directory containing the code imported as
+// "unicode" and want to run the tests for "unicode/utf8", you can type
+// "go test ./utf8" instead of needing to specify the full path.
+// Similarly, in the reverse situation, "go test .." will test "unicode" from
+// the "unicode/utf8" directory. Relative patterns are also allowed, like
+// "go test ./..." to test all subdirectories. See 'go help packages' for details
+// on the pattern syntax.
+//
+// Second, if you are compiling a Go program not in a work space,
+// you can use a relative path in an import statement in that program
+// to refer to nearby code also not in a work space.
+// This makes it easy to experiment with small multipackage programs
+// outside of the usual work spaces, but such programs cannot be
+// installed with "go install" (there is no work space in which to install them),
+// so they are rebuilt from scratch each time they are built.
+// To avoid ambiguity, Go programs cannot use relative import paths
+// within a work space.
+//
+// Remote import paths
+//
+// Certain import paths also
+// describe how to obtain the source code for the package using
+// a revision control system.
+//
+// A few common code hosting sites have special syntax:
+//
+// 	Bitbucket (Git, Mercurial)
+//
+// 		import "bitbucket.org/user/project"
+// 		import "bitbucket.org/user/project/sub/directory"
+//
+// 	GitHub (Git)
+//
+// 		import "github.com/user/project"
+// 		import "github.com/user/project/sub/directory"
+//
+// 	Launchpad (Bazaar)
+//
+// 		import "launchpad.net/project"
+// 		import "launchpad.net/project/series"
+// 		import "launchpad.net/project/series/sub/directory"
+//
+// 		import "launchpad.net/~user/project/branch"
+// 		import "launchpad.net/~user/project/branch/sub/directory"
+//
+// 	IBM DevOps Services (Git)
+//
+// 		import "hub.jazz.net/git/user/project"
+// 		import "hub.jazz.net/git/user/project/sub/directory"
+//
+// For code hosted on other servers, import paths may either be qualified
+// with the version control type, or the go tool can dynamically fetch
+// the import path over https/http and discover where the code resides
+// from a <meta> tag in the HTML.
+//
+// To declare the code location, an import path of the form
+//
+// 	repository.vcs/path
+//
+// specifies the given repository, with or without the .vcs suffix,
+// using the named version control system, and then the path inside
+// that repository.  The supported version control systems are:
+//
+// 	Bazaar      .bzr
+// 	Git         .git
+// 	Mercurial   .hg
+// 	Subversion  .svn
+//
+// For example,
+//
+// 	import "example.org/user/foo.hg"
+//
+// denotes the root directory of the Mercurial repository at
+// example.org/user/foo or foo.hg, and
+//
+// 	import "example.org/repo.git/foo/bar"
+//
+// denotes the foo/bar directory of the Git repository at
+// example.org/repo or repo.git.
+//
+// When a version control system supports multiple protocols,
+// each is tried in turn when downloading.  For example, a Git
+// download tries https://, then git+ssh://.
+//
+// If the import path is not a known code hosting site and also lacks a
+// version control qualifier, the go tool attempts to fetch the import
+// over https/http and looks for a <meta> tag in the document's HTML
+// <head>.
+//
+// The meta tag has the form:
+//
+// 	<meta name="go-import" content="import-prefix vcs repo-root">
+//
+// The import-prefix is the import path corresponding to the repository
+// root. It must be a prefix or an exact match of the package being
+// fetched with "go get". If it's not an exact match, another http
+// request is made at the prefix to verify the <meta> tags match.
+//
+// The meta tag should appear as early in the file as possible.
+// In particular, it should appear before any raw JavaScript or CSS,
+// to avoid confusing the go command's restricted parser.
+//
+// The vcs is one of "git", "hg", "svn", etc,
+//
+// The repo-root is the root of the version control system
+// containing a scheme and not containing a .vcs qualifier.
+//
+// For example,
+//
+// 	import "example.org/pkg/foo"
+//
+// will result in the following requests:
+//
+// 	https://example.org/pkg/foo?go-get=1 (preferred)
+// 	http://example.org/pkg/foo?go-get=1  (fallback, only with -insecure)
+//
+// If that page contains the meta tag
+//
+// 	<meta name="go-import" content="example.org git https://code.org/r/p/exproj">
+//
+// the go tool will verify that https://example.org/?go-get=1 contains the
+// same meta tag and then git clone https://code.org/r/p/exproj into
+// GOPATH/src/example.org.
+//
+// New downloaded packages are written to the first directory
+// listed in the GOPATH environment variable (see 'go help gopath').
+//
+// The go command attempts to download the version of the
+// package appropriate for the Go release being used.
+// Run 'go help get' for more.
+//
+// Import path checking
+//
+// When the custom import path feature described above redirects to a
+// known code hosting site, each of the resulting packages has two possible
+// import paths, using the custom domain or the known hosting site.
+//
+// A package statement is said to have an "import comment" if it is immediately
+// followed (before the next newline) by a comment of one of these two forms:
+//
+// 	package math // import "path"
+// 	package math /* import "path" */
+//
+// The go command will refuse to install a package with an import comment
+// unless it is being referred to by that import path. In this way, import comments
+// let package authors make sure the custom import path is used and not a
+// direct path to the underlying code hosting site.
+//
+// Import path checking is disabled for code found within vendor trees.
+// This makes it possible to copy code into alternate locations in vendor trees
+// without needing to update import comments.
+//
+// See https://golang.org/s/go14customimport for details.
+//
+//
+// Description of package lists
+//
+// Many commands apply to a set of packages:
+//
+// 	go action [packages]
+//
+// Usually, [packages] is a list of import paths.
+//
+// An import path that is a rooted path or that begins with
+// a . or .. element is interpreted as a file system path and
+// denotes the package in that directory.
+//
+// Otherwise, the import path P denotes the package found in
+// the directory DIR/src/P for some DIR listed in the GOPATH
+// environment variable (see 'go help gopath').
+//
+// If no import paths are given, the action applies to the
+// package in the current directory.
+//
+// There are four reserved names for paths that should not be used
+// for packages to be built with the go tool:
+//
+// - "main" denotes the top-level package in a stand-alone executable.
+//
+// - "all" expands to all package directories found in all the GOPATH
+// trees. For example, 'go list all' lists all the packages on the local
+// system.
+//
+// - "std" is like all but expands to just the packages in the standard
+// Go library.
+//
+// - "cmd" expands to the Go repository's commands and their
+// internal libraries.
+//
+// An import path is a pattern if it includes one or more "..." wildcards,
+// each of which can match any string, including the empty string and
+// strings containing slashes.  Such a pattern expands to all package
+// directories found in the GOPATH trees with names matching the
+// patterns.  As a special case, x/... matches x as well as x's subdirectories.
+// For example, net/... expands to net and packages in its subdirectories.
+//
+// An import path can also name a package to be downloaded from
+// a remote repository.  Run 'go help importpath' for details.
+//
+// Every package in a program must have a unique import path.
+// By convention, this is arranged by starting each path with a
+// unique prefix that belongs to you.  For example, paths used
+// internally at Google all begin with 'google', and paths
+// denoting remote repositories begin with the path to the code,
+// such as 'github.com/user/repo'.
+//
+// Packages in a program need not have unique package names,
+// but there are two reserved package names with special meaning.
+// The name main indicates a command, not a library.
+// Commands are built into binaries and cannot be imported.
+// The name documentation indicates documentation for
+// a non-Go program in the directory. Files in package documentation
+// are ignored by the go command.
+//
+// As a special case, if the package list is a list of .go files from a
+// single directory, the command is applied to a single synthesized
+// package made up of exactly those files, ignoring any build constraints
+// in those files and ignoring any other files in the directory.
+//
+// Directory and file names that begin with "." or "_" are ignored
+// by the go tool, as are directories named "testdata".
+//
+//
+// Description of testing flags
+//
+// The 'go test' command takes both flags that apply to 'go test' itself
+// and flags that apply to the resulting test binary.
+//
+// Several of the flags control profiling and write an execution profile
+// suitable for "go tool pprof"; run "go tool pprof -h" for more
+// information.  The --alloc_space, --alloc_objects, and --show_bytes
+// options of pprof control how the information is presented.
+//
+// The following flags are recognized by the 'go test' command and
+// control the execution of any test:
+//
+// 	-bench regexp
+// 	    Run (sub)benchmarks matching a regular expression.
+// 	    The given regular expression is split into smaller ones by
+// 	    top-level '/', where each must match the corresponding part of a
+// 	    benchmark's identifier.
+// 	    By default, no benchmarks run. To run all benchmarks,
+// 	    use '-bench .' or '-bench=.'.
+//
+// 	-benchmem
+// 	    Print memory allocation statistics for benchmarks.
+//
+// 	-benchtime t
+// 	    Run enough iterations of each benchmark to take t, specified
+// 	    as a time.Duration (for example, -benchtime 1h30s).
+// 	    The default is 1 second (1s).
+//
+// 	-blockprofile block.out
+// 	    Write a goroutine blocking profile to the specified file
+// 	    when all tests are complete.
+// 	    Writes test binary as -c would.
+//
+// 	-blockprofilerate n
+// 	    Control the detail provided in goroutine blocking profiles by
+// 	    calling runtime.SetBlockProfileRate with n.
+// 	    See 'go doc runtime.SetBlockProfileRate'.
+// 	    The profiler aims to sample, on average, one blocking event every
+// 	    n nanoseconds the program spends blocked.  By default,
+// 	    if -test.blockprofile is set without this flag, all blocking events
+// 	    are recorded, equivalent to -test.blockprofilerate=1.
+//
+// 	-count n
+// 	    Run each test and benchmark n times (default 1).
+// 	    If -cpu is set, run n times for each GOMAXPROCS value.
+// 	    Examples are always run once.
+//
+// 	-cover
+// 	    Enable coverage analysis.
+//
+// 	-covermode set,count,atomic
+// 	    Set the mode for coverage analysis for the package[s]
+// 	    being tested. The default is "set" unless -race is enabled,
+// 	    in which case it is "atomic".
+// 	    The values:
+// 		set: bool: does this statement run?
+// 		count: int: how many times does this statement run?
+// 		atomic: int: count, but correct in multithreaded tests;
+// 			significantly more expensive.
+// 	    Sets -cover.
+//
+// 	-coverpkg pkg1,pkg2,pkg3
+// 	    Apply coverage analysis in each test to the given list of packages.
+// 	    The default is for each test to analyze only the package being tested.
+// 	    Packages are specified as import paths.
+// 	    Sets -cover.
+//
+// 	-coverprofile cover.out
+// 	    Write a coverage profile to the file after all tests have passed.
+// 	    Sets -cover.
+//
+// 	-cpu 1,2,4
+// 	    Specify a list of GOMAXPROCS values for which the tests or
+// 	    benchmarks should be executed.  The default is the current value
+// 	    of GOMAXPROCS.
+//
+// 	-cpuprofile cpu.out
+// 	    Write a CPU profile to the specified file before exiting.
+// 	    Writes test binary as -c would.
+//
+// 	-memprofile mem.out
+// 	    Write a memory profile to the file after all tests have passed.
+// 	    Writes test binary as -c would.
+//
+// 	-memprofilerate n
+// 	    Enable more precise (and expensive) memory profiles by setting
+// 	    runtime.MemProfileRate.  See 'go doc runtime.MemProfileRate'.
+// 	    To profile all memory allocations, use -test.memprofilerate=1
+// 	    and pass --alloc_space flag to the pprof tool.
+//
+// 	-outputdir directory
+// 	    Place output files from profiling in the specified directory,
+// 	    by default the directory in which "go test" is running.
+//
+// 	-parallel n
+// 	    Allow parallel execution of test functions that call t.Parallel.
+// 	    The value of this flag is the maximum number of tests to run
+// 	    simultaneously; by default, it is set to the value of GOMAXPROCS.
+// 	    Note that -parallel only applies within a single test binary.
+// 	    The 'go test' command may run tests for different packages
+// 	    in parallel as well, according to the setting of the -p flag
+// 	    (see 'go help build').
+//
+// 	-run regexp
+// 	    Run only those tests and examples matching the regular expression.
+// 	    For tests the regular expression is split into smaller ones by
+// 	    top-level '/', where each must match the corresponding part of a
+// 	    test's identifier.
+//
+// 	-short
+// 	    Tell long-running tests to shorten their run time.
+// 	    It is off by default but set during all.bash so that installing
+// 	    the Go tree can run a sanity check but not spend time running
+// 	    exhaustive tests.
+//
+// 	-timeout t
+// 	    If a test runs longer than t, panic.
+// 	    The default is 10 minutes (10m).
+//
+// 	-trace trace.out
+// 	    Write an execution trace to the specified file before exiting.
+//
+// 	-v
+// 	    Verbose output: log all tests as they are run. Also print all
+// 	    text from Log and Logf calls even if the test succeeds.
+//
+// Each of these flags is also recognized with an optional 'test.' prefix,
+// as in -test.v. When invoking the generated test binary (the result of
+// 'go test -c') directly, however, the prefix is mandatory.
+//
+// The 'go test' command rewrites or removes recognized flags,
+// as appropriate, both before and after the optional package list,
+// before invoking the test binary.
+//
+// For instance, the command
+//
+// 	go test -v -myflag testdata -cpuprofile=prof.out -x
+//
+// will compile the test binary and then run it as
+//
+// 	pkg.test -test.v -myflag testdata -test.cpuprofile=prof.out
+//
+// (The -x flag is removed because it applies only to the go command's
+// execution, not to the test itself.)
+//
+// The test flags that generate profiles (other than for coverage) also
+// leave the test binary in pkg.test for use when analyzing the profiles.
+//
+// When 'go test' runs a test binary, it does so from within the
+// corresponding package's source code directory. Depending on the test,
+// it may be necessary to do the same when invoking a generated test
+// binary directly.
+//
+// The command-line package list, if present, must appear before any
+// flag not known to the go test command. Continuing the example above,
+// the package list would have to appear before -myflag, but could appear
+// on either side of -v.
+//
+// To keep an argument for a test binary from being interpreted as a
+// known flag or a package name, use -args (see 'go help test') which
+// passes the remainder of the command line through to the test binary
+// uninterpreted and unaltered.
+//
+// For instance, the command
+//
+// 	go test -v -args -x -v
+//
+// will compile the test binary and then run it as
+//
+// 	pkg.test -test.v -x -v
+//
+// Similarly,
+//
+// 	go test -args math
+//
+// will compile the test binary and then run it as
+//
+// 	pkg.test math
+//
+// In the first example, the -x and the second -v are passed through to the
+// test binary unchanged and with no effect on the go command itself.
+// In the second example, the argument math is passed through to the test
+// binary, instead of being interpreted as the package list.
+//
+//
+// Description of testing functions
+//
+// The 'go test' command expects to find test, benchmark, and example functions
+// in the "*_test.go" files corresponding to the package under test.
+//
+// A test function is one named TestXXX (where XXX is any alphanumeric string
+// not starting with a lower case letter) and should have the signature,
+//
+// 	func TestXXX(t *testing.T) { ... }
+//
+// A benchmark function is one named BenchmarkXXX and should have the signature,
+//
+// 	func BenchmarkXXX(b *testing.B) { ... }
+//
+// An example function is similar to a test function but, instead of using
+// *testing.T to report success or failure, prints output to os.Stdout.
+// If the last comment in the function starts with "Output:" then the output
+// is compared exactly against the comment (see examples below). If the last
+// comment begins with "Unordered output:" then the output is compared to the
+// comment, however the order of the lines is ignored. An example with no such
+// comment, or with no text after "Output:" is compiled but not executed.
+//
+// Godoc displays the body of ExampleXXX to demonstrate the use
+// of the function, constant, or variable XXX.  An example of a method M with
+// receiver type T or *T is named ExampleT_M.  There may be multiple examples
+// for a given function, constant, or variable, distinguished by a trailing _xxx,
+// where xxx is a suffix not beginning with an upper case letter.
+//
+// Here is an example of an example:
+//
+// 	func ExamplePrintln() {
+// 		Println("The output of\nthis example.")
+// 		// Output: The output of
+// 		// this example.
+// 	}
+//
+// Here is another example where the ordering of the output is ignored:
+//
+// 	func ExamplePerm() {
+// 		for _, value := range Perm(4) {
+// 			fmt.Println(value)
+// 		}
+//
+// 		// Unordered output: 4
+// 		// 2
+// 		// 1
+// 		// 3
+// 		// 0
+// 	}
+//
+// The entire test file is presented as the example when it contains a single
+// example function, at least one other function, type, variable, or constant
+// declaration, and no test or benchmark functions.
+//
+// See the documentation of the testing package for more information.
+//
+//
 package main
diff --git a/libgo/go/cmd/go/bootstrap.go b/libgo/go/cmd/go/bootstrap.go
index 1686df77afd..caa96769d84 100644
--- a/libgo/go/cmd/go/bootstrap.go
+++ b/libgo/go/cmd/go/bootstrap.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/build.go b/libgo/go/cmd/go/build.go
index d7a4a43093d..10116f282f0 100644
--- a/libgo/go/cmd/go/build.go
+++ b/libgo/go/cmd/go/build.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -48,6 +48,8 @@ When compiling multiple packages or a single non-main package,
 build compiles the packages but discards the resulting object,
 serving only as a check that the packages can be built.
 
+When compiling packages, build ignores files that end in '_test.go'.
+
 The -o flag, only allowed when compiling a single package,
 forces build to write the resulting executable or object
 to the named output file, instead of the default behavior described
@@ -65,8 +67,7 @@ and test commands:
 	-p n
 		the number of programs, such as build commands or
 		test binaries, that can be run in parallel.
-		The default is the number of CPUs available, except
-		on darwin/arm which defaults to 1.
+		The default is the number of CPUs available.
 	-race
 		enable data race detection.
 		Supported only on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64.
@@ -145,17 +146,6 @@ func init() {
 
 	addBuildFlags(cmdBuild)
 	addBuildFlags(cmdInstall)
-
-	if buildContext.GOOS == "darwin" {
-		switch buildContext.GOARCH {
-		case "arm", "arm64":
-			// darwin/arm cannot run multiple tests simultaneously.
-			// Parallelism is limited in go_darwin_arm_exec, but
-			// also needs to be limited here so go test std does not
-			// timeout tests that waiting to run.
-			buildP = 1
-		}
-	}
 }
 
 // Flags set by multiple commands.
@@ -352,6 +342,11 @@ func buildModeInit() {
 			}
 			return p
 		}
+		switch platform {
+		case "darwin/arm", "darwin/arm64":
+			codegenArg = "-shared"
+		default:
+		}
 		exeSuffix = ".a"
 		ldBuildmode = "c-archive"
 	case "c-shared":
@@ -374,6 +369,9 @@ func buildModeInit() {
 		case "android/arm", "android/arm64", "android/amd64", "android/386":
 			codegenArg = "-shared"
 			ldBuildmode = "pie"
+		case "darwin/arm", "darwin/arm64":
+			codegenArg = "-shared"
+			fallthrough
 		default:
 			ldBuildmode = "exe"
 		}
@@ -385,7 +383,7 @@ func buildModeInit() {
 			fatalf("-buildmode=pie not supported by gccgo")
 		} else {
 			switch platform {
-			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le",
+			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le", "linux/s390x",
 				"android/amd64", "android/arm", "android/arm64", "android/386":
 				codegenArg = "-shared"
 			default:
@@ -399,7 +397,7 @@ func buildModeInit() {
 			codegenArg = "-fPIC"
 		} else {
 			switch platform {
-			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le":
+			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le", "linux/s390x":
 			default:
 				fatalf("-buildmode=shared not supported on %s\n", platform)
 			}
@@ -417,7 +415,7 @@ func buildModeInit() {
 			codegenArg = "-fPIC"
 		} else {
 			switch platform {
-			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le":
+			case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le", "linux/s390x":
 				buildAsmflags = append(buildAsmflags, "-D=GOBUILDMODE_shared=1")
 			default:
 				fatalf("-linkshared not supported on %s\n", platform)
@@ -483,6 +481,7 @@ func runBuild(cmd *Command, args []string) {
 		p := pkgs[0]
 		p.target = *buildO
 		p.Stale = true // must build - not up to date
+		p.StaleReason = "build -o flag in use"
 		a := b.action(modeInstall, depMode, p)
 		b.do(a)
 		return
@@ -525,7 +524,7 @@ func isMetaPackage(name string) bool {
 }
 
 // libname returns the filename to use for the shared library when using
-// -buildmode=shared.  The rules we use are:
+// -buildmode=shared. The rules we use are:
 // Use arguments for special 'meta' packages:
 //	std --> libstd.so
 //	std cmd --> libstd,cmd.so
@@ -681,6 +680,7 @@ var (
 func init() {
 	goarch = buildContext.GOARCH
 	goos = buildContext.GOOS
+
 	if goos == "windows" {
 		exeSuffix = ".exe"
 	}
@@ -694,6 +694,7 @@ type builder struct {
 	work        string               // the temporary work directory (ends in filepath.Separator)
 	actionCache map[cacheKey]*action // a cache of already-constructed actions
 	mkdirCache  map[string]bool      // a cache of created directories
+	flagCache   map[string]bool      // a cache of supported compiler flags
 	print       func(args ...interface{}) (int, error)
 
 	output    sync.Mutex
@@ -795,7 +796,7 @@ func goFilesPackage(gofiles []string) *Package {
 
 	// Synthesize fake "directory" that only shows the named files,
 	// to make it look like this is a standard package or
-	// command directory.  So that local imports resolve
+	// command directory. So that local imports resolve
 	// consistently, the files must all be in the same directory.
 	var dirent []os.FileInfo
 	var dir string
@@ -853,6 +854,7 @@ func goFilesPackage(gofiles []string) *Package {
 
 	pkg.Target = pkg.target
 	pkg.Stale = true
+	pkg.StaleReason = "files named on command line"
 
 	computeStale(pkg)
 	return pkg
@@ -957,7 +959,7 @@ func (b *builder) action1(mode buildMode, depMode buildMode, p *Package, looksha
 	// If we are not doing a cross-build, then record the binary we'll
 	// generate for cgo as a dependency of the build of any package
 	// using cgo, to make sure we do not overwrite the binary while
-	// a package is using it.  If this is a cross-build, then the cgo we
+	// a package is using it. If this is a cross-build, then the cgo we
 	// are writing is not the cgo we need to use.
 	if goos == runtime.GOOS && goarch == runtime.GOARCH && !buildRace && !buildMSan && reqStdPkgSrc {
 		if (len(p.CgoFiles) > 0 || p.Standard && p.ImportPath == "runtime/cgo") && !buildLinkshared && buildBuildmode != "shared" {
@@ -993,7 +995,7 @@ func (b *builder) action1(mode buildMode, depMode buildMode, p *Package, looksha
 	}
 
 	if p.local && p.target == "" {
-		// Imported via local path.  No permanent target.
+		// Imported via local path. No permanent target.
 		mode = modeBuild
 	}
 	work := p.pkgdir
@@ -1041,7 +1043,7 @@ func (b *builder) action1(mode buildMode, depMode buildMode, p *Package, looksha
 			// the name will show up in ps listings. If the caller has specified
 			// a name, use that instead of a.out. The binary is generated
 			// in an otherwise empty subdirectory named exe to avoid
-			// naming conflicts.  The only possible conflict is if we were
+			// naming conflicts. The only possible conflict is if we were
 			// to create a top-level package named exe.
 			name := "a.out"
 			if p.exeName != "" {
@@ -1227,14 +1229,22 @@ func allArchiveActions(root *action) []*action {
 
 // do runs the action graph rooted at root.
 func (b *builder) do(root *action) {
+	/* Commented out for gccgo, which does not have osArchSupportsCgo.
+
+	if _, ok := osArchSupportsCgo[goos+"/"+goarch]; !ok && buildContext.Compiler == "gc" {
+		fmt.Fprintf(os.Stderr, "cmd/go: unsupported GOOS/GOARCH pair %s/%s\n", goos, goarch)
+		os.Exit(2)
+	}
+	*/
+
 	// Build list of all actions, assigning depth-first post-order priority.
 	// The original implementation here was a true queue
 	// (using a channel) but it had the effect of getting
 	// distracted by low-level leaf actions to the detriment
-	// of completing higher-level actions.  The order of
+	// of completing higher-level actions. The order of
 	// work does not matter much to overall execution time,
 	// but when running "go test std" it is nice to see each test
-	// results as soon as possible.  The priorities assigned
+	// results as soon as possible. The priorities assigned
 	// ensure that, all else being equal, the execution prefers
 	// to do what it would have done first in a simple depth-first
 	// dependency order traversal.
@@ -1331,18 +1341,15 @@ func (b *builder) do(root *action) {
 	wg.Wait()
 }
 
-// hasString reports whether s appears in the list of strings.
-func hasString(strings []string, s string) bool {
-	for _, t := range strings {
-		if s == t {
-			return true
-		}
-	}
-	return false
-}
-
 // build is the action for building a single package or command.
 func (b *builder) build(a *action) (err error) {
+	// Return an error for binary-only package.
+	// We only reach this if isStale believes the binary form is
+	// either not present or not usable.
+	if a.p.BinaryOnly {
+		return fmt.Errorf("missing or invalid package binary for binary-only package %s", a.p.ImportPath)
+	}
+
 	// Return an error if the package has CXX files but it's not using
 	// cgo nor SWIG, since the CXX files can only be processed by cgo
 	// and SWIG.
@@ -1355,6 +1362,12 @@ func (b *builder) build(a *action) (err error) {
 		return fmt.Errorf("can't build package %s because it contains Objective-C files (%s) but it's not using cgo nor SWIG",
 			a.p.ImportPath, strings.Join(a.p.MFiles, ","))
 	}
+	// Same as above for Fortran files
+	if len(a.p.FFiles) > 0 && !a.p.usesCgo() && !a.p.usesSwig() {
+		return fmt.Errorf("can't build package %s because it contains Fortran files (%s) but it's not using cgo nor SWIG",
+			a.p.ImportPath, strings.Join(a.p.FFiles, ","))
+	}
+
 	defer func() {
 		if err != nil && err != errPrintedOutput {
 			err = fmt.Errorf("go build %s: %v", a.p.ImportPath, err)
@@ -1421,6 +1434,8 @@ func (b *builder) build(a *action) (err error) {
 		// cgo and non-cgo worlds, so it necessarily has files in both.
 		// In that case gcc only gets the gcc_* files.
 		var gccfiles []string
+		gccfiles = append(gccfiles, cfiles...)
+		cfiles = nil
 		if a.p.Standard && a.p.ImportPath == "runtime/cgo" {
 			filter := func(files, nongcc, gcc []string) ([]string, []string) {
 				for _, f := range files {
@@ -1432,11 +1447,9 @@ func (b *builder) build(a *action) (err error) {
 				}
 				return nongcc, gcc
 			}
-			cfiles, gccfiles = filter(cfiles, cfiles[:0], gccfiles)
 			sfiles, gccfiles = filter(sfiles, sfiles[:0], gccfiles)
 		} else {
-			gccfiles = append(cfiles, sfiles...)
-			cfiles = nil
+			gccfiles = append(gccfiles, sfiles...)
 			sfiles = nil
 		}
 
@@ -1444,7 +1457,7 @@ func (b *builder) build(a *action) (err error) {
 		if a.cgo != nil && a.cgo.target != "" {
 			cgoExe = a.cgo.target
 		}
-		outGo, outObj, err := b.cgo(a.p, cgoExe, obj, pcCFLAGS, pcLDFLAGS, cgofiles, gccfiles, cxxfiles, a.p.MFiles)
+		outGo, outObj, err := b.cgo(a.p, cgoExe, obj, pcCFLAGS, pcLDFLAGS, cgofiles, gccfiles, cxxfiles, a.p.MFiles, a.p.FFiles)
 		if err != nil {
 			return err
 		}
@@ -1552,7 +1565,7 @@ func (b *builder) build(a *action) (err error) {
 
 	// NOTE(rsc): On Windows, it is critically important that the
 	// gcc-compiled objects (cgoObjects) be listed after the ordinary
-	// objects in the archive.  I do not know why this is.
+	// objects in the archive. I do not know why this is.
 	// https://golang.org/issue/2601
 	objects = append(objects, cgoObjects...)
 
@@ -1658,7 +1671,7 @@ func (b *builder) install(a *action) (err error) {
 	}
 
 	// remove object dir to keep the amount of
-	// garbage down in a large build.  On an operating system
+	// garbage down in a large build. On an operating system
 	// with aggressive buffering, cleaning incrementally like
 	// this keeps the intermediate objects from hitting the disk.
 	if !buildWork {
@@ -1803,7 +1816,7 @@ func (b *builder) copyFile(a *action, dst, src string, perm os.FileMode, force b
 	df, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
 	if err != nil && toolIsWindows {
 		// Windows does not allow deletion of a binary file
-		// while it is executing.  Try to move it out of the way.
+		// while it is executing. Try to move it out of the way.
 		// If the move fails, which is likely, we'll try again the
 		// next time we do an install of this binary.
 		if err := os.Rename(dst, dst+"~"); err == nil {
@@ -1933,7 +1946,7 @@ func (b *builder) showcmd(dir string, format string, args ...interface{}) {
 // The output is expected to contain references to 'dir', usually
 // the source directory for the package that has failed to build.
 // showOutput rewrites mentions of dir with a relative path to dir
-// when the relative path is shorter.  This is usually more pleasant.
+// when the relative path is shorter. This is usually more pleasant.
 // For example, if fmt doesn't compile and we are in src/html,
 // the output is
 //
@@ -1991,7 +2004,7 @@ func relPaths(paths []string) []string {
 // errPrintedOutput is a special error indicating that a command failed
 // but that it generated output as well, and that output has already
 // been printed, so there's no point showing 'exit status 1' or whatever
-// the wait status was.  The main executor, builder.do, knows not to
+// the wait status was. The main executor, builder.do, knows not to
 // print this error.
 var errPrintedOutput = errors.New("already printed output - no need to show error")
 
@@ -2060,7 +2073,7 @@ func (b *builder) runOut(dir string, desc string, env []string, cmdargs ...inter
 		err := cmd.Run()
 
 		// cmd.Run will fail on Unix if some other process has the binary
-		// we want to run open for writing.  This can happen here because
+		// we want to run open for writing. This can happen here because
 		// we build and install the cgo command and then run it.
 		// If another command was kicked off while we were writing the
 		// cgo binary, the child process for that command may be holding
@@ -2072,27 +2085,27 @@ func (b *builder) runOut(dir string, desc string, env []string, cmdargs ...inter
 		// The answer is that running a command is fork and exec.
 		// A child forked while the cgo fd is open inherits that fd.
 		// Until the child has called exec, it holds the fd open and the
-		// kernel will not let us run cgo.  Even if the child were to close
+		// kernel will not let us run cgo. Even if the child were to close
 		// the fd explicitly, it would still be open from the time of the fork
 		// until the time of the explicit close, and the race would remain.
 		//
 		// On Unix systems, this results in ETXTBSY, which formats
 		// as "text file busy".  Rather than hard-code specific error cases,
-		// we just look for that string.  If this happens, sleep a little
-		// and try again.  We let this happen three times, with increasing
+		// we just look for that string. If this happens, sleep a little
+		// and try again. We let this happen three times, with increasing
 		// sleep lengths: 100+200+400 ms = 0.7 seconds.
 		//
 		// An alternate solution might be to split the cmd.Run into
 		// separate cmd.Start and cmd.Wait, and then use an RWLock
 		// to make sure that copyFile only executes when no cmd.Start
-		// call is in progress.  However, cmd.Start (really syscall.forkExec)
+		// call is in progress. However, cmd.Start (really syscall.forkExec)
 		// only guarantees that when it returns, the exec is committed to
-		// happen and succeed.  It uses a close-on-exec file descriptor
+		// happen and succeed. It uses a close-on-exec file descriptor
 		// itself to determine this, so we know that when cmd.Start returns,
 		// at least one close-on-exec file descriptor has been closed.
 		// However, we cannot be sure that all of them have been closed,
 		// so the program might still encounter ETXTBSY even with such
-		// an RWLock.  The race window would be smaller, perhaps, but not
+		// an RWLock. The race window would be smaller, perhaps, but not
 		// guaranteed to be gone.
 		//
 		// Sleeping when we observe the race seems to be the most reliable
@@ -2142,7 +2155,7 @@ func (b *builder) mkdir(dir string) error {
 	b.exec.Lock()
 	defer b.exec.Unlock()
 	// We can be a little aggressive about being
-	// sure directories exist.  Skip repeated calls.
+	// sure directories exist. Skip repeated calls.
 	if b.mkdirCache[dir] {
 		return nil
 	}
@@ -2180,7 +2193,6 @@ func mkAbs(dir, f string) string {
 type toolchain interface {
 	// gc runs the compiler in a specific directory on a set of files
 	// and returns the name of the generated output file.
-	// The compiler runs in the directory dir.
 	gc(b *builder, p *Package, archive, obj string, asmhdr bool, importArgs []string, gofiles []string) (ofile string, out []byte, err error)
 	// cc runs the toolchain's C compiler in a directory on a C file
 	// to produce an output file.
@@ -2282,7 +2294,7 @@ func (gcToolchain) gc(b *builder, p *Package, archive, obj string, asmhdr bool,
 	// so that it can give good error messages about forward declarations.
 	// Exceptions: a few standard packages have forward declarations for
 	// pieces supplied behind-the-scenes by package runtime.
-	extFiles := len(p.CgoFiles) + len(p.CFiles) + len(p.CXXFiles) + len(p.MFiles) + len(p.SFiles) + len(p.SysoFiles) + len(p.SwigFiles) + len(p.SwigCXXFiles)
+	extFiles := len(p.CgoFiles) + len(p.CFiles) + len(p.CXXFiles) + len(p.MFiles) + len(p.FFiles) + len(p.SFiles) + len(p.SysoFiles) + len(p.SwigFiles) + len(p.SwigCXXFiles)
 	if p.Standard {
 		switch p.ImportPath {
 		case "bytes", "net", "os", "runtime/pprof", "sync", "time":
@@ -2334,7 +2346,15 @@ func (gcToolchain) asm(b *builder, p *Package, obj, ofile, sfile string) error {
 	// Add -I pkg/GOOS_GOARCH so #include "textflag.h" works in .s files.
 	inc := filepath.Join(goroot, "pkg", "include")
 	sfile = mkAbs(p.Dir, sfile)
-	args := []interface{}{buildToolExec, tool("asm"), "-o", ofile, "-trimpath", b.work, "-I", obj, "-I", inc, "-D", "GOOS_" + goos, "-D", "GOARCH_" + goarch, buildAsmflags, sfile}
+	args := []interface{}{buildToolExec, tool("asm"), "-o", ofile, "-trimpath", b.work, "-I", obj, "-I", inc, "-D", "GOOS_" + goos, "-D", "GOARCH_" + goarch, buildAsmflags}
+	if p.ImportPath == "runtime" && goarch == "386" {
+		for _, arg := range buildAsmflags {
+			if arg == "-dynlink" {
+				args = append(args, "-D=GOBUILDMODE_shared=1")
+			}
+		}
+	}
+	args = append(args, sfile)
 	if err := b.run(p.Dir, p.ImportPath, nil, args...); err != nil {
 		return err
 	}
@@ -2381,8 +2401,10 @@ func (gcToolchain) pack(b *builder, p *Package, objDir, afile string, ofiles []s
 
 	// The archive file should have been created by the compiler.
 	// Since it used to not work that way, verify.
-	if _, err := os.Stat(absAfile); err != nil {
-		fatalf("os.Stat of archive file failed: %v", err)
+	if !buildN {
+		if _, err := os.Stat(absAfile); err != nil {
+			fatalf("os.Stat of archive file failed: %v", err)
+		}
 	}
 
 	if buildN || buildX {
@@ -2629,18 +2651,23 @@ func (gccgoToolchain) pack(b *builder, p *Package, objDir, afile string, ofiles
 	return b.run(p.Dir, p.ImportPath, nil, "ar", "rc", mkAbs(objDir, afile), absOfiles)
 }
 
-func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions []*action, mainpkg string, ofiles []string) error {
+func (tools gccgoToolchain) link(b *builder, root *action, out string, allactions []*action, mainpkg string, ofiles []string, buildmode, desc string) error {
 	// gccgo needs explicit linking with all package dependencies,
 	// and all LDFLAGS from cgo dependencies.
-	apackagesSeen := make(map[*Package]bool)
+	apackagePathsSeen := make(map[string]bool)
 	afiles := []string{}
 	shlibs := []string{}
-	xfiles := []string{}
 	ldflags := b.gccArchArgs()
 	cgoldflags := []string{}
 	usesCgo := false
-	cxx := len(root.p.CXXFiles) > 0 || len(root.p.SwigCXXFiles) > 0
-	objc := len(root.p.MFiles) > 0
+	cxx := false
+	objc := false
+	fortran := false
+	if root.p != nil {
+		cxx = len(root.p.CXXFiles) > 0 || len(root.p.SwigCXXFiles) > 0
+		objc = len(root.p.MFiles) > 0
+		fortran = len(root.p.FFiles) > 0
+	}
 
 	readCgoFlags := func(flagsFile string) error {
 		flags, err := ioutil.ReadFile(flagsFile)
@@ -2687,11 +2714,11 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 		}
 
 		newarchive := newa.Name()
-		err = b.run(b.work, root.p.ImportPath, nil, "ar", "x", newarchive, "_cgo_flags")
+		err = b.run(b.work, desc, nil, "ar", "x", newarchive, "_cgo_flags")
 		if err != nil {
 			return "", err
 		}
-		err = b.run(".", root.p.ImportPath, nil, "ar", "d", newarchive, "_cgo_flags")
+		err = b.run(".", desc, nil, "ar", "d", newarchive, "_cgo_flags")
 		if err != nil {
 			return "", err
 		}
@@ -2723,10 +2750,10 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 			// rather than the 'build' location (which may not exist any
 			// more). We still need to traverse the dependencies of the
 			// build action though so saying
-			// if apackagesSeen[a.p] { return }
+			// if apackagePathsSeen[a.p.ImportPath] { return }
 			// doesn't work.
-			if !apackagesSeen[a.p] {
-				apackagesSeen[a.p] = true
+			if !apackagePathsSeen[a.p.ImportPath] {
+				apackagePathsSeen[a.p.ImportPath] = true
 				target := a.target
 				if len(a.p.CgoFiles) > 0 {
 					target, err = readAndRemoveCgoFlags(target)
@@ -2734,17 +2761,7 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 						return
 					}
 				}
-				if a.p.fake && a.p.external {
-					// external _tests, if present must come before
-					// internal _tests. Store these on a separate list
-					// and place them at the head after this loop.
-					xfiles = append(xfiles, target)
-				} else if a.p.fake {
-					// move _test files to the top of the link order
-					afiles = append([]string{target}, afiles...)
-				} else {
-					afiles = append(afiles, target)
-				}
+				afiles = append(afiles, target)
 			}
 		}
 		if strings.HasSuffix(a.target, ".so") {
@@ -2764,7 +2781,6 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 			return err
 		}
 	}
-	afiles = append(xfiles, afiles...)
 
 	for _, a := range allactions {
 		// Gather CgoLDFLAGS, but not from standard packages.
@@ -2789,6 +2805,9 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 		if len(a.p.MFiles) > 0 {
 			objc = true
 		}
+		if len(a.p.FFiles) > 0 {
+			fortran = true
+		}
 	}
 
 	for i, o := range ofiles {
@@ -2805,7 +2824,9 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 
 	ldflags = append(ldflags, cgoldflags...)
 	ldflags = append(ldflags, envList("CGO_LDFLAGS", "")...)
-	ldflags = append(ldflags, root.p.CgoLDFLAGS...)
+	if root.p != nil {
+		ldflags = append(ldflags, root.p.CgoLDFLAGS...)
+	}
 
 	ldflags = stringList("-Wl,-(", ldflags, "-Wl,-)")
 
@@ -2820,7 +2841,7 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 	}
 
 	var realOut string
-	switch ldBuildmode {
+	switch buildmode {
 	case "exe":
 		if usesCgo && goos == "linux" {
 			ldflags = append(ldflags, "-Wl,-E")
@@ -2836,7 +2857,7 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 		// initialization code.
 		//
 		// The user remains responsible for linking against
-		// -lgo -lpthread -lm in the final link.  We can't use
+		// -lgo -lpthread -lm in the final link. We can't use
 		// -r to pick them up because we can't combine
 		// split-stack and non-split-stack code in a single -r
 		// link, and libgo picks up non-split-stack code from
@@ -2855,12 +2876,14 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 
 	case "c-shared":
 		ldflags = append(ldflags, "-shared", "-nostdlib", "-Wl,--whole-archive", "-lgolibbegin", "-Wl,--no-whole-archive", "-lgo", "-lgcc_s", "-lgcc", "-lc", "-lgcc")
+	case "shared":
+		ldflags = append(ldflags, "-zdefs", "-shared", "-nostdlib", "-lgo", "-lgcc_s", "-lgcc", "-lc")
 
 	default:
-		fatalf("-buildmode=%s not supported for gccgo", ldBuildmode)
+		fatalf("-buildmode=%s not supported for gccgo", buildmode)
 	}
 
-	switch ldBuildmode {
+	switch buildmode {
 	case "exe", "c-shared":
 		if cxx {
 			ldflags = append(ldflags, "-lstdc++")
@@ -2868,43 +2891,40 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
 		if objc {
 			ldflags = append(ldflags, "-lobjc")
 		}
+		if fortran {
+			fc := os.Getenv("FC")
+			if fc == "" {
+				fc = "gfortran"
+			}
+			// support gfortran out of the box and let others pass the correct link options
+			// via CGO_LDFLAGS
+			if strings.Contains(fc, "gfortran") {
+				ldflags = append(ldflags, "-lgfortran")
+			}
+		}
 	}
 
-	if err := b.run(".", root.p.ImportPath, nil, tools.linker(), "-o", out, ofiles, ldflags, buildGccgoflags); err != nil {
+	if err := b.run(".", desc, nil, tools.linker(), "-o", out, ofiles, ldflags, buildGccgoflags); err != nil {
 		return err
 	}
 
-	switch ldBuildmode {
+	switch buildmode {
 	case "c-archive":
-		if err := b.run(".", root.p.ImportPath, nil, "ar", "rc", realOut, out); err != nil {
+		if err := b.run(".", desc, nil, "ar", "rc", realOut, out); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
+func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions []*action, mainpkg string, ofiles []string) error {
+	return tools.link(b, root, out, allactions, mainpkg, ofiles, ldBuildmode, root.p.ImportPath)
+}
+
 func (tools gccgoToolchain) ldShared(b *builder, toplevelactions []*action, out string, allactions []*action) error {
-	args := []string{"-o", out, "-shared", "-nostdlib", "-zdefs", "-Wl,--whole-archive"}
-	for _, a := range toplevelactions {
-		args = append(args, a.target)
-	}
-	args = append(args, "-Wl,--no-whole-archive", "-shared", "-nostdlib", "-lgo", "-lgcc_s", "-lgcc", "-lc")
-	shlibs := []string{}
-	for _, a := range allactions {
-		if strings.HasSuffix(a.target, ".so") {
-			shlibs = append(shlibs, a.target)
-		}
-	}
-	for _, shlib := range shlibs {
-		args = append(
-			args,
-			"-L"+filepath.Dir(shlib),
-			"-Wl,-rpath="+filepath.Dir(shlib),
-			"-l"+strings.TrimSuffix(
-				strings.TrimPrefix(filepath.Base(shlib), "lib"),
-				".so"))
-	}
-	return b.run(".", out, nil, tools.linker(), args, buildGccgoflags)
+	fakeRoot := &action{}
+	fakeRoot.deps = toplevelactions
+	return tools.link(b, fakeRoot, out, allactions, "", nil, "shared", out)
 }
 
 func (tools gccgoToolchain) cc(b *builder, p *Package, objdir, ofile, cfile string) error {
@@ -2962,6 +2982,11 @@ func (b *builder) gxx(p *Package, out string, flags []string, cxxfile string) er
 	return b.ccompile(p, out, flags, cxxfile, b.gxxCmd(p.Dir))
 }
 
+// gfortran runs the gfortran Fortran compiler to create an object from a single Fortran file.
+func (b *builder) gfortran(p *Package, out string, flags []string, ffile string) error {
+	return b.ccompile(p, out, flags, ffile, b.gfortranCmd(p.Dir))
+}
+
 // ccompile runs the given C or C++ compiler and creates an object from a single source file.
 func (b *builder) ccompile(p *Package, out string, flags []string, file string, compiler []string) error {
 	file = mkAbs(p.Dir, file)
@@ -2991,6 +3016,11 @@ func (b *builder) gxxCmd(objdir string) []string {
 	return b.ccompilerCmd("CXX", defaultCXX, objdir)
 }
 
+// gfortranCmd returns a gfortran command line prefix.
+func (b *builder) gfortranCmd(objdir string) []string {
+	return b.ccompilerCmd("FC", "gfortran", objdir)
+}
+
 // ccompilerCmd returns a command line prefix for the given environment
 // variable and using the default command when the variable is empty.
 func (b *builder) ccompilerCmd(envvar, defcmd, objdir string) []string {
@@ -3028,6 +3058,17 @@ func (b *builder) ccompilerCmd(envvar, defcmd, objdir string) []string {
 	// disable word wrapping in error messages
 	a = append(a, "-fmessage-length=0")
 
+	// Tell gcc not to include the work directory in object files.
+	if b.gccSupportsFlag("-fdebug-prefix-map=a=b") {
+		a = append(a, "-fdebug-prefix-map="+b.work+"=/tmp/go-build")
+	}
+
+	// Tell gcc not to include flags in object files, which defeats the
+	// point of -fdebug-prefix-map above.
+	if b.gccSupportsFlag("-gno-record-gcc-switches") {
+		a = append(a, "-gno-record-gcc-switches")
+	}
+
 	// On OS X, some of the compilers behave as if -fno-common
 	// is always set, and the Mach-O linker in 6l/8l assumes this.
 	// See https://golang.org/issue/3253.
@@ -3042,19 +3083,24 @@ func (b *builder) ccompilerCmd(envvar, defcmd, objdir string) []string {
 // -no-pie must be passed when doing a partial link with -Wl,-r. But -no-pie is
 // not supported by all compilers.
 func (b *builder) gccSupportsNoPie() bool {
-	if goos != "linux" {
-		// On some BSD platforms, error messages from the
-		// compiler make it to the console despite cmd.Std*
-		// all being nil. As -no-pie is only required on linux
-		// systems so far, we only test there.
-		return false
+	return b.gccSupportsFlag("-no-pie")
+}
+
+// gccSupportsFlag checks to see if the compiler supports a flag.
+func (b *builder) gccSupportsFlag(flag string) bool {
+	b.exec.Lock()
+	defer b.exec.Unlock()
+	if b, ok := b.flagCache[flag]; ok {
+		return b
 	}
-	src := filepath.Join(b.work, "trivial.c")
-	if err := ioutil.WriteFile(src, []byte{}, 0666); err != nil {
-		return false
+	if b.flagCache == nil {
+		src := filepath.Join(b.work, "trivial.c")
+		if err := ioutil.WriteFile(src, []byte{}, 0666); err != nil {
+			return false
+		}
+		b.flagCache = make(map[string]bool)
 	}
-	cmdArgs := b.gccCmd(b.work)
-	cmdArgs = append(cmdArgs, "-no-pie", "-c", "trivial.c")
+	cmdArgs := append(envList("CC", defaultCC), flag, "-c", "trivial.c")
 	if buildN || buildX {
 		b.showcmd(b.work, "%s", joinUnambiguously(cmdArgs))
 		if buildN {
@@ -3063,9 +3109,11 @@ func (b *builder) gccSupportsNoPie() bool {
 	}
 	cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
 	cmd.Dir = b.work
-	cmd.Env = envForDir(cmd.Dir, os.Environ())
+	cmd.Env = mergeEnvLists([]string{"LC_ALL=C"}, envForDir(cmd.Dir, os.Environ()))
 	out, err := cmd.CombinedOutput()
-	return err == nil && !bytes.Contains(out, []byte("unrecognized"))
+	supported := err == nil && !bytes.Contains(out, []byte("unrecognized"))
+	b.flagCache[flag] = supported
+	return supported
 }
 
 // gccArchArgs returns arguments to pass to gcc based on the architecture.
@@ -3077,6 +3125,10 @@ func (b *builder) gccArchArgs() []string {
 		return []string{"-m64"}
 	case "arm":
 		return []string{"-marm"} // not thumb
+	case "s390x":
+		return []string{"-m64", "-march=z196"}
+	case "mips64", "mips64le":
+		return []string{"-mabi=64"}
 	}
 	return nil
 }
@@ -3091,8 +3143,8 @@ func envList(key, def string) []string {
 	return strings.Fields(v)
 }
 
-// Return the flags to use when invoking the C or C++ compilers, or cgo.
-func (b *builder) cflags(p *Package, def bool) (cppflags, cflags, cxxflags, ldflags []string) {
+// Return the flags to use when invoking the C, C++ or Fortran compilers, or cgo.
+func (b *builder) cflags(p *Package, def bool) (cppflags, cflags, cxxflags, fflags, ldflags []string) {
 	var defaults string
 	if def {
 		defaults = "-g -O2"
@@ -3101,15 +3153,16 @@ func (b *builder) cflags(p *Package, def bool) (cppflags, cflags, cxxflags, ldfl
 	cppflags = stringList(envList("CGO_CPPFLAGS", ""), p.CgoCPPFLAGS)
 	cflags = stringList(envList("CGO_CFLAGS", defaults), p.CgoCFLAGS)
 	cxxflags = stringList(envList("CGO_CXXFLAGS", defaults), p.CgoCXXFLAGS)
+	fflags = stringList(envList("CGO_FFLAGS", defaults), p.CgoFFLAGS)
 	ldflags = stringList(envList("CGO_LDFLAGS", defaults), p.CgoLDFLAGS)
 	return
 }
 
 var cgoRe = regexp.MustCompile(`[/\\:]`)
 
-func (b *builder) cgo(p *Package, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofiles, gccfiles, gxxfiles, mfiles []string) (outGo, outObj []string, err error) {
-	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, cgoLDFLAGS := b.cflags(p, true)
-	_, cgoexeCFLAGS, _, _ := b.cflags(p, false)
+func (b *builder) cgo(p *Package, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofiles, gccfiles, gxxfiles, mfiles, ffiles []string) (outGo, outObj []string, err error) {
+	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, cgoFFLAGS, cgoLDFLAGS := b.cflags(p, true)
+	_, cgoexeCFLAGS, _, _, _ := b.cflags(p, false)
 	cgoCPPFLAGS = append(cgoCPPFLAGS, pcCFLAGS...)
 	cgoLDFLAGS = append(cgoLDFLAGS, pcLDFLAGS...)
 	// If we are compiling Objective-C code, then we need to link against libobjc
@@ -3117,6 +3170,19 @@ func (b *builder) cgo(p *Package, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofi
 		cgoLDFLAGS = append(cgoLDFLAGS, "-lobjc")
 	}
 
+	// Likewise for Fortran, except there are many Fortran compilers.
+	// Support gfortran out of the box and let others pass the correct link options
+	// via CGO_LDFLAGS
+	if len(ffiles) > 0 {
+		fc := os.Getenv("FC")
+		if fc == "" {
+			fc = "gfortran"
+		}
+		if strings.Contains(fc, "gfortran") {
+			cgoLDFLAGS = append(cgoLDFLAGS, "-lgfortran")
+		}
+	}
+
 	if buildMSan && p.ImportPath != "runtime/cgo" {
 		cgoCFLAGS = append([]string{"-fsanitize=memory"}, cgoCFLAGS...)
 		cgoLDFLAGS = append([]string{"-fsanitize=memory"}, cgoLDFLAGS...)
@@ -3221,7 +3287,7 @@ func (b *builder) cgo(p *Package, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofi
 		case strings.HasPrefix(f, "-fsanitize="):
 			continue
 		// runpath flags not applicable unless building a shared
-		// object or executable; see issue 12115 for details.  This
+		// object or executable; see issue 12115 for details. This
 		// is necessary as Go currently does not offer a way to
 		// specify the set of LDFLAGS that only apply to shared
 		// objects.
@@ -3284,6 +3350,17 @@ func (b *builder) cgo(p *Package, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofi
 		outObj = append(outObj, ofile)
 	}
 
+	fflags := stringList(cgoCPPFLAGS, cgoFFLAGS)
+	for _, file := range ffiles {
+		// Append .o to the file, just in case the pkg has file.c and file.f
+		ofile := obj + cgoRe.ReplaceAllString(file, "_") + ".o"
+		if err := b.gfortran(p, ofile, fflags, file); err != nil {
+			return nil, nil, err
+		}
+		linkobj = append(linkobj, ofile)
+		outObj = append(outObj, ofile)
+	}
+
 	linkobj = append(linkobj, p.SysoFiles...)
 	dynobj := obj + "_cgo_.o"
 	pie := (goarch == "arm" && goos == "linux") || goos == "android"
@@ -3449,6 +3526,13 @@ func (b *builder) swigVersionCheck() error {
 	return swigCheck
 }
 
+// Find the value to pass for the -intgosize option to swig.
+var (
+	swigIntSizeOnce  sync.Once
+	swigIntSize      string
+	swigIntSizeError error
+)
+
 // This code fails to build if sizeof(int) <= 32
 const swigIntSizeCode = `
 package main
@@ -3456,8 +3540,8 @@ const i int = 1 << 32
 `
 
 // Determine the size of int on the target system for the -intgosize option
-// of swig >= 2.0.9
-func (b *builder) swigIntSize(obj string) (intsize string, err error) {
+// of swig >= 2.0.9.  Run only once.
+func (b *builder) swigDoIntSize(obj string) (intsize string, err error) {
 	if buildN {
 		return "$INTBITS", nil
 	}
@@ -3475,9 +3559,18 @@ func (b *builder) swigIntSize(obj string) (intsize string, err error) {
 	return "64", nil
 }
 
+// Determine the size of int on the target system for the -intgosize option
+// of swig >= 2.0.9.
+func (b *builder) swigIntSize(obj string) (intsize string, err error) {
+	swigIntSizeOnce.Do(func() {
+		swigIntSize, swigIntSizeError = b.swigDoIntSize(obj)
+	})
+	return swigIntSize, swigIntSizeError
+}
+
 // Run SWIG on one SWIG input file.
 func (b *builder) swigOne(p *Package, file, obj string, pcCFLAGS []string, cxx bool, intgosize string) (outGo, outC string, err error) {
-	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, _ := b.cflags(p, true)
+	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, _, _ := b.cflags(p, true)
 	var cflags []string
 	if cxx {
 		cflags = stringList(cgoCPPFLAGS, pcCFLAGS, cgoCXXFLAGS)
@@ -3545,12 +3638,12 @@ func (b *builder) swigOne(p *Package, file, obj string, pcCFLAGS []string, cxx b
 
 // disableBuildID adjusts a linker command line to avoid creating a
 // build ID when creating an object file rather than an executable or
-// shared library.  Some systems, such as Ubuntu, always add
+// shared library. Some systems, such as Ubuntu, always add
 // --build-id to every link, but we don't want a build ID when we are
-// producing an object file.  On some of those system a plain -r (not
+// producing an object file. On some of those system a plain -r (not
 // -Wl,-r) will turn off --build-id, but clang 3.0 doesn't support a
-// plain -r.  I don't know how to turn off --build-id when using clang
-// other than passing a trailing --build-id=none.  So that is what we
+// plain -r. I don't know how to turn off --build-id when using clang
+// other than passing a trailing --build-id=none. So that is what we
 // do, but only on systems likely to support it, which is to say,
 // systems that normally use gold or the GNU linker.
 func (b *builder) disableBuildID(ldflags []string) []string {
diff --git a/libgo/go/cmd/go/clean.go b/libgo/go/cmd/go/clean.go
index 16054a5b5bc..7b07150743a 100644
--- a/libgo/go/cmd/go/clean.go
+++ b/libgo/go/cmd/go/clean.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/context.go b/libgo/go/cmd/go/context.go
index 68e518259f4..94cd54d00d8 100644
--- a/libgo/go/cmd/go/context.go
+++ b/libgo/go/cmd/go/context.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -26,6 +26,7 @@ func newContext(c *build.Context) *Context {
 		GOARCH:        c.GOARCH,
 		GOOS:          c.GOOS,
 		GOROOT:        c.GOROOT,
+		GOPATH:        c.GOPATH,
 		CgoEnabled:    c.CgoEnabled,
 		UseAllFiles:   c.UseAllFiles,
 		Compiler:      c.Compiler,
diff --git a/libgo/go/cmd/go/discovery.go b/libgo/go/cmd/go/discovery.go
index f6992e9e93e..b60eaef7398 100644
--- a/libgo/go/cmd/go/discovery.go
+++ b/libgo/go/cmd/go/discovery.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/doc.go b/libgo/go/cmd/go/doc.go
index 9b8b8dfc249..829983950f8 100644
--- a/libgo/go/cmd/go/doc.go
+++ b/libgo/go/cmd/go/doc.go
@@ -1,7 +1,9 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:generate ./mkalldocs.sh
+
 package main
 
 var cmdDoc = &Command{
diff --git a/libgo/go/cmd/go/env.go b/libgo/go/cmd/go/env.go
index 24f612756b6..8aaaf463292 100644
--- a/libgo/go/cmd/go/env.go
+++ b/libgo/go/cmd/go/env.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -33,11 +33,6 @@ func mkEnv() []envVar {
 	var b builder
 	b.init()
 
-	vendorExpValue := "0"
-	if go15VendorExperiment {
-		vendorExpValue = "1"
-	}
-
 	env := []envVar{
 		{"GOARCH", goarch},
 		{"GOBIN", gobin},
@@ -49,7 +44,6 @@ func mkEnv() []envVar {
 		{"GORACE", os.Getenv("GORACE")},
 		{"GOROOT", goroot},
 		{"GOTOOLDIR", toolDir},
-		{"GO15VENDOREXPERIMENT", vendorExpValue},
 
 		// disable escape codes in clang errors
 		{"TERM", "dumb"},
diff --git a/libgo/go/cmd/go/fix.go b/libgo/go/cmd/go/fix.go
index 94fd22e3c21..3af7adb4e1c 100644
--- a/libgo/go/cmd/go/fix.go
+++ b/libgo/go/cmd/go/fix.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/fmt.go b/libgo/go/cmd/go/fmt.go
index 57c02ad2647..4ed7722575e 100644
--- a/libgo/go/cmd/go/fmt.go
+++ b/libgo/go/cmd/go/fmt.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/generate.go b/libgo/go/cmd/go/generate.go
index cb54018bab5..3c6065e89aa 100644
--- a/libgo/go/cmd/go/generate.go
+++ b/libgo/go/cmd/go/generate.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -14,10 +14,8 @@ import (
 	"os/exec"
 	"path/filepath"
 	"regexp"
-	"runtime"
 	"strconv"
 	"strings"
-	"unicode"
 )
 
 var cmdGenerate = &Command{
@@ -277,8 +275,8 @@ func isGoGenerate(buf []byte) bool {
 // single go:generate command.
 func (g *Generator) setEnv() {
 	g.env = []string{
-		"GOARCH=" + runtime.GOARCH,
-		"GOOS=" + runtime.GOOS,
+		"GOARCH=" + buildContext.GOARCH,
+		"GOOS=" + buildContext.GOOS,
 		"GOFILE=" + g.file,
 		"GOLINE=" + strconv.Itoa(g.lineNum),
 		"GOPACKAGE=" + g.pkg,
@@ -371,17 +369,6 @@ func (g *Generator) expandVar(word string) string {
 	return os.Getenv(word)
 }
 
-// identLength returns the length of the identifier beginning the string.
-func (g *Generator) identLength(word string) int {
-	for i, r := range word {
-		if r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r) {
-			continue
-		}
-		return i
-	}
-	return len(word)
-}
-
 // setShorthand installs a new shorthand as defined by a -command directive.
 func (g *Generator) setShorthand(words []string) {
 	// Create command shorthand.
diff --git a/libgo/go/cmd/go/generate_test.go b/libgo/go/cmd/go/generate_test.go
index ba0669278e7..dd116e6cc61 100644
--- a/libgo/go/cmd/go/generate_test.go
+++ b/libgo/go/cmd/go/generate_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/get.go b/libgo/go/cmd/go/get.go
index a298049a9d2..19858f7e55d 100644
--- a/libgo/go/cmd/go/get.go
+++ b/libgo/go/cmd/go/get.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -19,8 +19,8 @@ var cmdGet = &Command{
 	UsageLine: "get [-d] [-f] [-fix] [-insecure] [-t] [-u] [build flags] [packages]",
 	Short:     "download and install packages and dependencies",
 	Long: `
-Get downloads and installs the packages named by the import paths,
-along with their dependencies.
+Get downloads the packages named by the import paths, along with their
+dependencies. It then installs the named packages, like 'go install'.
 
 The -d flag instructs get to stop after downloading the packages; that is,
 it instructs get not to install the packages.
@@ -45,7 +45,7 @@ missing packages but does not use it to look for updates to existing packages.
 
 Get also accepts build flags to control the installation. See 'go help build'.
 
-When checking out a new package, get creates the target directory 
+When checking out a new package, get creates the target directory
 GOPATH/src/<import-path>. If the GOPATH contains multiple entries,
 get uses the first one. See 'go help gopath'.
 
@@ -55,8 +55,7 @@ rule is that if the local installation is running version "go1", get
 searches for a branch or tag named "go1". If no such version exists it
 retrieves the most recent version of the package.
 
-Unless vendoring support is disabled (see 'go help gopath'),
-when go get checks out or updates a Git repository,
+When go get checks out or updates a Git repository,
 it also updates any git submodules referenced by the repository.
 
 Get never checks out or updates code stored in vendor directories.
@@ -112,13 +111,21 @@ func runGet(cmd *Command, args []string) {
 
 	// Code we downloaded and all code that depends on it
 	// needs to be evicted from the package cache so that
-	// the information will be recomputed.  Instead of keeping
+	// the information will be recomputed. Instead of keeping
 	// track of the reverse dependency information, evict
 	// everything.
 	for name := range packageCache {
 		delete(packageCache, name)
 	}
 
+	// In order to rebuild packages information completely,
+	// we need to clear commands cache. Command packages are
+	// referring to evicted packages from the package cache.
+	// This leads to duplicated loads of the standard packages.
+	for name := range cmdCache {
+		delete(cmdCache, name)
+	}
+
 	args = importPaths(args)
 	packagesForBuild(args)
 
@@ -134,7 +141,7 @@ func runGet(cmd *Command, args []string) {
 }
 
 // downloadPaths prepares the list of paths to pass to download.
-// It expands ... patterns that can be expanded.  If there is no match
+// It expands ... patterns that can be expanded. If there is no match
 // for a particular pattern, downloadPaths leaves it in the result list,
 // in the hope that we can figure out the repository from the
 // initial ...-free prefix.
@@ -145,7 +152,7 @@ func downloadPaths(args []string) []string {
 		if strings.Contains(a, "...") {
 			var expand []string
 			// Use matchPackagesInFS to avoid printing
-			// warnings.  They will be printed by the
+			// warnings. They will be printed by the
 			// eventual call to importPaths instead.
 			if build.IsLocalImport(a) {
 				expand = matchPackagesInFS(a)
@@ -228,16 +235,6 @@ func download(arg string, parent *Package, stk *importStack, mode int) {
 			stk.pop()
 			return
 		}
-
-		// Warn that code.google.com is shutting down.  We
-		// issue the warning here because this is where we
-		// have the import stack.
-		if strings.HasPrefix(p.ImportPath, "code.google.com") {
-			fmt.Fprintf(os.Stderr, "warning: code.google.com is shutting down; import path %v will stop working\n", p.ImportPath)
-			if len(*stk) > 1 {
-				fmt.Fprintf(os.Stderr, "warning: package %v\n", strings.Join(*stk, "\n\timports "))
-			}
-		}
 		stk.pop()
 
 		args := []string{arg}
@@ -347,8 +344,8 @@ func downloadPackage(p *Package) error {
 	}
 
 	if p.build.SrcRoot != "" {
-		// Directory exists.  Look for checkout along path to src.
-		vcs, rootPath, err = vcsForDir(p)
+		// Directory exists. Look for checkout along path to src.
+		vcs, rootPath, err = vcsFromDir(p.Dir, p.build.SrcRoot)
 		if err != nil {
 			return err
 		}
@@ -356,7 +353,7 @@ func downloadPackage(p *Package) error {
 
 		// Double-check where it came from.
 		if *getU && vcs.remoteRepo != nil {
-			dir := filepath.Join(p.build.SrcRoot, rootPath)
+			dir := filepath.Join(p.build.SrcRoot, filepath.FromSlash(rootPath))
 			remote, err := vcs.remoteRepo(vcs, dir)
 			if err != nil {
 				return err
@@ -391,7 +388,7 @@ func downloadPackage(p *Package) error {
 	}
 
 	if p.build.SrcRoot == "" {
-		// Package not found.  Put in first directory of $GOPATH.
+		// Package not found. Put in first directory of $GOPATH.
 		list := filepath.SplitList(buildContext.GOPATH)
 		if len(list) == 0 {
 			return fmt.Errorf("cannot download, $GOPATH not set. For more details see: go help gopath")
@@ -403,7 +400,7 @@ func downloadPackage(p *Package) error {
 		p.build.SrcRoot = filepath.Join(list[0], "src")
 		p.build.PkgRoot = filepath.Join(list[0], "pkg")
 	}
-	root := filepath.Join(p.build.SrcRoot, rootPath)
+	root := filepath.Join(p.build.SrcRoot, filepath.FromSlash(rootPath))
 	// If we've considered this repository already, don't do it again.
 	if downloadRootCache[root] {
 		return nil
@@ -422,7 +419,7 @@ func downloadPackage(p *Package) error {
 		return fmt.Errorf("%s exists but is not a directory", meta)
 	}
 	if err != nil {
-		// Metadata directory does not exist.  Prepare to checkout new copy.
+		// Metadata directory does not exist. Prepare to checkout new copy.
 		// Some version control tools require the target directory not to exist.
 		// We require that too, just to avoid stepping on existing work.
 		if _, err := os.Stat(root); err == nil {
diff --git a/libgo/go/cmd/go/go11.go b/libgo/go/cmd/go/go11.go
index 8a434dfed1c..7e383f4b5b0 100644
--- a/libgo/go/cmd/go/go11.go
+++ b/libgo/go/cmd/go/go11.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/go_test.go b/libgo/go/cmd/go/go_test.go
index 39e0f3e56d5..66c641347cb 100644
--- a/libgo/go/cmd/go/go_test.go
+++ b/libgo/go/cmd/go/go_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -109,7 +109,7 @@ func TestMain(m *testing.M) {
 	os.Exit(r)
 }
 
-// The length of an mtime tick on this system.  This is an estimate of
+// The length of an mtime tick on this system. This is an estimate of
 // how long we need to sleep to ensure that the mtime of two files is
 // different.
 // We used to try to be clever but that didn't always work (see golang.org/issue/12205).
@@ -181,7 +181,7 @@ func (tg *testgoData) pwd() string {
 	return wd
 }
 
-// cd changes the current directory to the named directory.  Note that
+// cd changes the current directory to the named directory. Note that
 // using this means that the test must not be run in parallel with any
 // other tests.
 func (tg *testgoData) cd(dir string) {
@@ -325,7 +325,7 @@ func (tg *testgoData) getStderr() string {
 }
 
 // doGrepMatch looks for a regular expression in a buffer, and returns
-// whether it is found.  The regular expression is matched against
+// whether it is found. The regular expression is matched against
 // each line separately, as with the grep command.
 func (tg *testgoData) doGrepMatch(match string, b *bytes.Buffer) bool {
 	if !tg.ran {
@@ -341,7 +341,7 @@ func (tg *testgoData) doGrepMatch(match string, b *bytes.Buffer) bool {
 }
 
 // doGrep looks for a regular expression in a buffer and fails if it
-// is not found.  The name argument is the name of the output we are
+// is not found. The name argument is the name of the output we are
 // searching, "output" or "error".  The msg argument is logged on
 // failure.
 func (tg *testgoData) doGrep(match string, b *bytes.Buffer, name, msg string) {
@@ -375,7 +375,7 @@ func (tg *testgoData) grepBoth(match, msg string) {
 }
 
 // doGrepNot looks for a regular expression in a buffer and fails if
-// it is found.  The name and msg arguments are as for doGrep.
+// it is found. The name and msg arguments are as for doGrep.
 func (tg *testgoData) doGrepNot(match string, b *bytes.Buffer, name, msg string) {
 	if tg.doGrepMatch(match, b) {
 		tg.t.Log(msg)
@@ -421,18 +421,6 @@ func (tg *testgoData) doGrepCount(match string, b *bytes.Buffer) int {
 	return c
 }
 
-// grepCountStdout returns the number of times a regexp is seen in
-// standard output.
-func (tg *testgoData) grepCountStdout(match string) int {
-	return tg.doGrepCount(match, &tg.stdout)
-}
-
-// grepCountStderr returns the number of times a regexp is seen in
-// standard error.
-func (tg *testgoData) grepCountStderr(match string) int {
-	return tg.doGrepCount(match, &tg.stderr)
-}
-
 // grepCountBoth returns the number of times a regexp is seen in both
 // standard output and standard error.
 func (tg *testgoData) grepCountBoth(match string) int {
@@ -440,8 +428,8 @@ func (tg *testgoData) grepCountBoth(match string) int {
 }
 
 // creatingTemp records that the test plans to create a temporary file
-// or directory.  If the file or directory exists already, it will be
-// removed.  When the test completes, the file or directory will be
+// or directory. If the file or directory exists already, it will be
+// removed. When the test completes, the file or directory will be
 // removed if it exists.
 func (tg *testgoData) creatingTemp(path string) {
 	if filepath.IsAbs(path) && !strings.HasPrefix(path, tg.tempdir) {
@@ -457,7 +445,7 @@ func (tg *testgoData) creatingTemp(path string) {
 	tg.temps = append(tg.temps, path)
 }
 
-// makeTempdir makes a temporary directory for a run of testgo.  If
+// makeTempdir makes a temporary directory for a run of testgo. If
 // the temporary directory was already created, this does nothing.
 func (tg *testgoData) makeTempdir() {
 	if tg.tempdir == "" {
@@ -501,6 +489,16 @@ func (tg *testgoData) path(name string) string {
 	return filepath.Join(tg.tempdir, name)
 }
 
+// mustExist fails if path does not exist.
+func (tg *testgoData) mustExist(path string) {
+	if _, err := os.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			tg.t.Fatalf("%s does not exist but should", path)
+		}
+		tg.t.Fatalf("%s stat failed: %v", path, err)
+	}
+}
+
 // mustNotExist fails if path exists.
 func (tg *testgoData) mustNotExist(path string) {
 	if _, err := os.Stat(path); err == nil || !os.IsNotExist(err) {
@@ -536,32 +534,43 @@ func (tg *testgoData) wantArchive(path string) {
 	}
 }
 
-// isStale returns whether pkg is stale.
-func (tg *testgoData) isStale(pkg string) bool {
-	tg.run("list", "-f", "{{.Stale}}", pkg)
-	switch v := strings.TrimSpace(tg.getStdout()); v {
-	case "true":
-		return true
-	case "false":
-		return false
-	default:
-		tg.t.Fatalf("unexpected output checking staleness of package %v: %v", pkg, v)
-		panic("unreachable")
+// isStale reports whether pkg is stale, and why
+func (tg *testgoData) isStale(pkg string) (bool, string) {
+	tg.run("list", "-f", "{{.Stale}}:{{.StaleReason}}", pkg)
+	v := strings.TrimSpace(tg.getStdout())
+	f := strings.SplitN(v, ":", 2)
+	if len(f) == 2 {
+		switch f[0] {
+		case "true":
+			return true, f[1]
+		case "false":
+			return false, f[1]
+		}
 	}
+	tg.t.Fatalf("unexpected output checking staleness of package %v: %v", pkg, v)
+	panic("unreachable")
 }
 
 // wantStale fails with msg if pkg is not stale.
-func (tg *testgoData) wantStale(pkg, msg string) {
-	if !tg.isStale(pkg) {
+func (tg *testgoData) wantStale(pkg, reason, msg string) {
+	stale, why := tg.isStale(pkg)
+	if !stale {
 		tg.t.Fatal(msg)
 	}
+	if reason == "" && why != "" || !strings.Contains(why, reason) {
+		tg.t.Errorf("wrong reason for Stale=true: %q, want %q", why, reason)
+	}
 }
 
 // wantNotStale fails with msg if pkg is stale.
-func (tg *testgoData) wantNotStale(pkg, msg string) {
-	if tg.isStale(pkg) {
+func (tg *testgoData) wantNotStale(pkg, reason, msg string) {
+	stale, why := tg.isStale(pkg)
+	if stale {
 		tg.t.Fatal(msg)
 	}
+	if reason == "" && why != "" || !strings.Contains(why, reason) {
+		tg.t.Errorf("wrong reason for Stale=false: %q, want %q", why, reason)
+	}
 }
 
 // cleanup cleans up a test that runs testgo.
@@ -581,32 +590,6 @@ func (tg *testgoData) cleanup() {
 	}
 }
 
-// resetReadOnlyFlagAll resets windows read-only flag
-// set on path and any children it contains.
-// The flag is set by git and has to be removed.
-// os.Remove refuses to remove files with read-only flag set.
-func (tg *testgoData) resetReadOnlyFlagAll(path string) {
-	fi, err := os.Stat(path)
-	if err != nil {
-		tg.t.Fatalf("resetReadOnlyFlagAll(%q) failed: %v", path, err)
-	}
-	if !fi.IsDir() {
-		err := os.Chmod(path, 0666)
-		if err != nil {
-			tg.t.Fatalf("resetReadOnlyFlagAll(%q) failed: %v", path, err)
-		}
-	}
-	fd, err := os.Open(path)
-	if err != nil {
-		tg.t.Fatalf("resetReadOnlyFlagAll(%q) failed: %v", path, err)
-	}
-	defer fd.Close()
-	names, _ := fd.Readdirnames(-1)
-	for _, name := range names {
-		tg.resetReadOnlyFlagAll(path + string(filepath.Separator) + name)
-	}
-}
-
 // failSSH puts an ssh executable in the PATH that always fails.
 // This is to stub out uses of ssh by go get.
 func (tg *testgoData) failSSH() {
@@ -720,7 +703,7 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 	tg.tempFile("d1/src/p1/p1.go", `package p1`)
 	tg.setenv("GOPATH", tg.path("d1"))
 	tg.run("install", "-a", "p1")
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale, incorrectly")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale, incorrectly")
 	tg.sleep()
 
 	// Changing mtime and content of runtime/internal/sys/sys.go
@@ -729,28 +712,28 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 	sys := runtime.GOROOT() + "/src/runtime/internal/sys/sys.go"
 	restore := addNL(sys)
 	defer restore()
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale, incorrectly, after updating runtime/internal/sys/sys.go")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale, incorrectly, after updating runtime/internal/sys/sys.go")
 	restore()
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale, incorrectly, after restoring runtime/internal/sys/sys.go")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale, incorrectly, after restoring runtime/internal/sys/sys.go")
 
 	// But changing runtime/internal/sys/zversion.go should have an effect:
 	// that's how we tell when we flip from one release to another.
 	zversion := runtime.GOROOT() + "/src/runtime/internal/sys/zversion.go"
 	restore = addNL(zversion)
 	defer restore()
-	tg.wantStale("p1", "./testgo list claims p1 is NOT stale, incorrectly, after changing to new release")
+	tg.wantStale("p1", "build ID mismatch", "./testgo list claims p1 is NOT stale, incorrectly, after changing to new release")
 	restore()
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale, incorrectly, after changing back to old release")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale, incorrectly, after changing back to old release")
 	addNL(zversion)
-	tg.wantStale("p1", "./testgo list claims p1 is NOT stale, incorrectly, after changing again to new release")
+	tg.wantStale("p1", "build ID mismatch", "./testgo list claims p1 is NOT stale, incorrectly, after changing again to new release")
 	tg.run("install", "p1")
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale after building with new release")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale after building with new release")
 
 	// Restore to "old" release.
 	restore()
-	tg.wantStale("p1", "./testgo list claims p1 is NOT stale, incorrectly, after changing to old release after new build")
+	tg.wantStale("p1", "build ID mismatch", "./testgo list claims p1 is NOT stale, incorrectly, after changing to old release after new build")
 	tg.run("install", "p1")
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale after building with old release")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale after building with old release")
 
 	// Everything is out of date. Rebuild to leave things in a better state.
 	tg.run("install", "std")
@@ -833,8 +816,8 @@ func TestGoInstallRebuildsStalePackagesInOtherGOPATH(t *testing.T) {
 	sep := string(filepath.ListSeparator)
 	tg.setenv("GOPATH", tg.path("d1")+sep+tg.path("d2"))
 	tg.run("install", "p1")
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale, incorrectly")
-	tg.wantNotStale("p2", "./testgo list claims p2 is stale, incorrectly")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale, incorrectly")
+	tg.wantNotStale("p2", "", "./testgo list claims p2 is stale, incorrectly")
 	tg.sleep()
 	if f, err := os.OpenFile(tg.path("d2/src/p2/p2.go"), os.O_WRONLY|os.O_APPEND, 0); err != nil {
 		t.Fatal(err)
@@ -843,12 +826,12 @@ func TestGoInstallRebuildsStalePackagesInOtherGOPATH(t *testing.T) {
 	} else {
 		tg.must(f.Close())
 	}
-	tg.wantStale("p2", "./testgo list claims p2 is NOT stale, incorrectly")
-	tg.wantStale("p1", "./testgo list claims p1 is NOT stale, incorrectly")
+	tg.wantStale("p2", "newer source file", "./testgo list claims p2 is NOT stale, incorrectly")
+	tg.wantStale("p1", "stale dependency", "./testgo list claims p1 is NOT stale, incorrectly")
 
 	tg.run("install", "p1")
-	tg.wantNotStale("p2", "./testgo list claims p2 is stale after reinstall, incorrectly")
-	tg.wantNotStale("p1", "./testgo list claims p1 is stale after reinstall, incorrectly")
+	tg.wantNotStale("p2", "", "./testgo list claims p2 is stale after reinstall, incorrectly")
+	tg.wantNotStale("p1", "", "./testgo list claims p1 is stale after reinstall, incorrectly")
 }
 
 func TestGoInstallDetectsRemovedFiles(t *testing.T) {
@@ -862,13 +845,13 @@ func TestGoInstallDetectsRemovedFiles(t *testing.T) {
 		package mypkg`)
 	tg.setenv("GOPATH", tg.path("."))
 	tg.run("install", "mypkg")
-	tg.wantNotStale("mypkg", "./testgo list mypkg claims mypkg is stale, incorrectly")
+	tg.wantNotStale("mypkg", "", "./testgo list mypkg claims mypkg is stale, incorrectly")
 	// z.go was not part of the build; removing it is okay.
 	tg.must(os.Remove(tg.path("src/mypkg/z.go")))
-	tg.wantNotStale("mypkg", "./testgo list mypkg claims mypkg is stale after removing z.go; should not be stale")
+	tg.wantNotStale("mypkg", "", "./testgo list mypkg claims mypkg is stale after removing z.go; should not be stale")
 	// y.go was part of the package; removing it should be detected.
 	tg.must(os.Remove(tg.path("src/mypkg/y.go")))
-	tg.wantStale("mypkg", "./testgo list mypkg claims mypkg is NOT stale after removing y.go; should be stale")
+	tg.wantStale("mypkg", "build ID mismatch", "./testgo list mypkg claims mypkg is NOT stale after removing y.go; should be stale")
 }
 
 func TestWildcardMatchesSyntaxErrorDirs(t *testing.T) {
@@ -931,13 +914,13 @@ func TestGoInstallDetectsRemovedFilesInPackageMain(t *testing.T) {
 		package main`)
 	tg.setenv("GOPATH", tg.path("."))
 	tg.run("install", "mycmd")
-	tg.wantNotStale("mycmd", "./testgo list mypkg claims mycmd is stale, incorrectly")
+	tg.wantNotStale("mycmd", "", "./testgo list mypkg claims mycmd is stale, incorrectly")
 	// z.go was not part of the build; removing it is okay.
 	tg.must(os.Remove(tg.path("src/mycmd/z.go")))
-	tg.wantNotStale("mycmd", "./testgo list mycmd claims mycmd is stale after removing z.go; should not be stale")
+	tg.wantNotStale("mycmd", "", "./testgo list mycmd claims mycmd is stale after removing z.go; should not be stale")
 	// y.go was part of the package; removing it should be detected.
 	tg.must(os.Remove(tg.path("src/mycmd/y.go")))
-	tg.wantStale("mycmd", "./testgo list mycmd claims mycmd is NOT stale after removing y.go; should be stale")
+	tg.wantStale("mycmd", "build ID mismatch", "./testgo list mycmd claims mycmd is NOT stale after removing y.go; should be stale")
 }
 
 func testLocalRun(tg *testgoData, exepath, local, match string) {
@@ -1105,8 +1088,8 @@ func testMove(t *testing.T, vcs, url, base, config string) {
 	}
 	if vcs == "git" {
 		// git will ask for a username and password when we
-		// run go get -d -f -u.  An empty username and
-		// password will work.  Prevent asking by setting
+		// run go get -d -f -u. An empty username and
+		// password will work. Prevent asking by setting
 		// GIT_ASKPASS.
 		tg.creatingTemp("sink" + exeSuffix)
 		tg.tempFile("src/sink/sink.go", `package main; func main() {}`)
@@ -1178,7 +1161,7 @@ func TestImportCommentConflict(t *testing.T) {
 	tg.grepStderr("found import comments", "go build did not mention comment conflict")
 }
 
-// cmd/go: custom import path checking should not apply to github.com/xxx/yyy.
+// cmd/go: custom import path checking should not apply to Go packages without import comment.
 func TestIssue10952(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 	if _, err := exec.LookPath("git"); err != nil {
@@ -1193,11 +1176,38 @@ func TestIssue10952(t *testing.T) {
 	const importPath = "github.com/zombiezen/go-get-issue-10952"
 	tg.run("get", "-d", "-u", importPath)
 	repoDir := tg.path("src/" + importPath)
-	defer tg.resetReadOnlyFlagAll(repoDir)
 	tg.runGit(repoDir, "remote", "set-url", "origin", "https://"+importPath+".git")
 	tg.run("get", "-d", "-u", importPath)
 }
 
+// Test git clone URL that uses SCP-like syntax and custom import path checking.
+func TestIssue11457(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("skipping because git binary not found")
+	}
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.tempDir("src")
+	tg.setenv("GOPATH", tg.path("."))
+	const importPath = "github.com/rsc/go-get-issue-11457"
+	tg.run("get", "-d", "-u", importPath)
+	repoDir := tg.path("src/" + importPath)
+	tg.runGit(repoDir, "remote", "set-url", "origin", "git@github.com:rsc/go-get-issue-11457")
+
+	// At this time, custom import path checking compares remotes verbatim (rather than
+	// just the host and path, skipping scheme and user), so we expect go get -u to fail.
+	// However, the goal of this test is to verify that gitRemoteRepo correctly parsed
+	// the SCP-like syntax, and we expect it to appear in the error message.
+	tg.runFail("get", "-d", "-u", importPath)
+	want := " is checked out from ssh://git@github.com/rsc/go-get-issue-11457"
+	if !strings.HasSuffix(strings.TrimSpace(tg.getStderr()), want) {
+		t.Error("expected clone URL to appear in stderr")
+	}
+}
+
 func TestGetGitDefaultBranch(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 	if _, err := exec.LookPath("git"); err != nil {
@@ -1217,7 +1227,6 @@ func TestGetGitDefaultBranch(t *testing.T) {
 
 	tg.run("get", "-d", importPath)
 	repoDir := tg.path("src/" + importPath)
-	defer tg.resetReadOnlyFlagAll(repoDir)
 	tg.runGit(repoDir, "branch", "--contains", "HEAD")
 	tg.grepStdout(`\* another-branch`, "not on correct default branch")
 
@@ -1226,14 +1235,6 @@ func TestGetGitDefaultBranch(t *testing.T) {
 	tg.grepStdout(`\* another-branch`, "not on correct default branch")
 }
 
-func TestDisallowedCSourceFiles(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.runFail("build", "badc")
-	tg.grepStderr("C source files not allowed", "go test did not say C source files not allowed")
-}
-
 func TestErrorMessageForSyntaxErrorInTestGoFileSaysFAIL(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
@@ -1337,19 +1338,35 @@ func TestPackageMainTestImportsArchiveNotBinary(t *testing.T) {
 	tg.sleep()
 	tg.run("test", "main_test")
 	tg.run("install", "main_test")
-	tg.wantNotStale("main_test", "after go install, main listed as stale")
+	tg.wantNotStale("main_test", "", "after go install, main listed as stale")
 	tg.run("test", "main_test")
 }
 
+// The runtime version string takes one of two forms:
+// "go1.X[.Y]" for Go releases, and "devel +hash" at tip.
+// Determine whether we are in a released copy by
+// inspecting the version.
+var isGoRelease = strings.HasPrefix(runtime.Version(), "go1")
+
 // Issue 12690
 func TestPackageNotStaleWithTrailingSlash(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
+
+	// Make sure the packages below are not stale.
+	tg.run("install", "runtime", "os", "io")
+
 	goroot := runtime.GOROOT()
 	tg.setenv("GOROOT", goroot+"/")
-	tg.wantNotStale("runtime", "with trailing slash in GOROOT, runtime listed as stale")
-	tg.wantNotStale("os", "with trailing slash in GOROOT, os listed as stale")
-	tg.wantNotStale("io", "with trailing slash in GOROOT, io listed as stale")
+
+	want := ""
+	if isGoRelease {
+		want = "standard package in Go release distribution"
+	}
+
+	tg.wantNotStale("runtime", want, "with trailing slash in GOROOT, runtime listed as stale")
+	tg.wantNotStale("os", want, "with trailing slash in GOROOT, os listed as stale")
+	tg.wantNotStale("io", want, "with trailing slash in GOROOT, io listed as stale")
 }
 
 // With $GOBIN set, binaries get installed to $GOBIN.
@@ -1397,28 +1414,6 @@ func TestInstallToGOBINCommandLinePackage(t *testing.T) {
 	tg.wantExecutable("testdata/bin1/helloworld"+exeSuffix, "go install testdata/src/go-cmd-test/helloworld.go did not write testdata/bin1/helloworld")
 }
 
-func TestGodocInstalls(t *testing.T) {
-	testenv.MustHaveExternalNetwork(t)
-
-	// godoc installs into GOBIN
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.parallel()
-	tg.tempDir("gobin")
-	tg.setenv("GOPATH", tg.path("."))
-	tg.setenv("GOBIN", tg.path("gobin"))
-	tg.run("get", "golang.org/x/tools/cmd/godoc")
-	tg.wantExecutable(tg.path("gobin/godoc"), "did not install godoc to $GOBIN")
-	tg.unsetenv("GOBIN")
-
-	// godoc installs into GOROOT
-	goroot := runtime.GOROOT()
-	tg.setenv("GOROOT", goroot)
-	tg.check(os.RemoveAll(filepath.Join(goroot, "bin", "godoc")))
-	tg.run("install", "golang.org/x/tools/cmd/godoc")
-	tg.wantExecutable(filepath.Join(goroot, "bin", "godoc"), "did not install godoc to $GOROOT/bin")
-}
-
 func TestGoGetNonPkg(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 
@@ -1508,7 +1503,7 @@ func TestGoTestWithPackageListedMultipleTimes(t *testing.T) {
 	defer tg.cleanup()
 	tg.parallel()
 	tg.run("test", "errors", "errors", "errors", "errors", "errors")
-	if strings.Index(strings.TrimSpace(tg.getStdout()), "\n") != -1 {
+	if strings.Contains(strings.TrimSpace(tg.getStdout()), "\n") {
 		t.Error("go test errors errors errors errors errors tested the same package multiple times")
 	}
 }
@@ -1537,7 +1532,7 @@ func TestGoListCmdOnlyShowsCommands(t *testing.T) {
 	tg.run("list", "cmd")
 	out := strings.TrimSpace(tg.getStdout())
 	for _, line := range strings.Split(out, "\n") {
-		if strings.Index(line, "cmd/") == -1 {
+		if !strings.Contains(line, "cmd/") {
 			t.Error("go list cmd shows non-commands")
 			break
 		}
@@ -1657,8 +1652,8 @@ func TestLdflagsArgumentsWithSpacesIssue3941(t *testing.T) {
 		func main() {
 			println(extern)
 		}`)
-	tg.run("run", "-ldflags", `-X main.extern "hello world"`, tg.path("main.go"))
-	tg.grepStderr("^hello world", `ldflags -X main.extern 'hello world' failed`)
+	tg.run("run", "-ldflags", `-X "main.extern=hello world"`, tg.path("main.go"))
+	tg.grepStderr("^hello world", `ldflags -X "main.extern=hello world"' failed`)
 }
 
 func TestGoTestCpuprofileLeavesBinaryBehind(t *testing.T) {
@@ -1726,7 +1721,6 @@ func TestSymlinksVendor(t *testing.T) {
 
 	tg := testgo(t)
 	defer tg.cleanup()
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.tempDir("gopath/src/dir1/vendor/v")
 	tg.tempFile("gopath/src/dir1/p.go", "package main\nimport _ `v`\nfunc main(){}")
 	tg.tempFile("gopath/src/dir1/vendor/v/v.go", "package v")
@@ -1879,7 +1873,9 @@ func TestShadowingLogic(t *testing.T) {
 	}
 	// The output will have makeImportValid applies, but we only
 	// bother to deal with characters we might reasonably see.
-	pwdForwardSlash = strings.Replace(pwdForwardSlash, ":", "_", -1)
+	for _, r := range " :" {
+		pwdForwardSlash = strings.Replace(pwdForwardSlash, string(r), "_", -1)
+	}
 	want := "(_" + pwdForwardSlash + "/testdata/shadow/root1/src/math) (" + filepath.Join(runtime.GOROOT(), "src", "math") + ")"
 	if strings.TrimSpace(tg.getStdout()) != want {
 		t.Error("shadowed math is not shadowed; looking for", want)
@@ -2001,6 +1997,27 @@ func TestCoverageUsesActualSettingToOverrideEvenForRace(t *testing.T) {
 	checkCoverage(tg, data)
 }
 
+func TestBuildDryRunWithCgo(t *testing.T) {
+	if !canCgo {
+		t.Skip("skipping because cgo not enabled")
+	}
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.tempFile("foo.go", `package main
+
+/*
+#include <limits.h>
+*/
+import "C"
+
+func main() {
+        println(C.INT_MAX)
+}`)
+	tg.run("build", "-n", tg.path("foo.go"))
+	tg.grepStderrNot(`os.Stat .* no such file or directory`, "unexpected stat of archive file")
+}
+
 func TestCoverageWithCgo(t *testing.T) {
 	if !canCgo {
 		t.Skip("skipping because cgo not enabled")
@@ -2106,10 +2123,33 @@ func main() { C.f() }`)
 	tg.grepStderr(`gccgo.*\-L alibpath \-lalib`, `no Go-inline "#cgo LDFLAGS:" ("-L alibpath -lalib") passed to gccgo linking stage`)
 }
 
-func TestListTemplateCanUseContextFunction(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.run("list", "-f", "GOARCH: {{context.GOARCH}}")
+func TestListTemplateContextFunction(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	for _, tt := range []struct {
+		v    string
+		want string
+	}{
+		{"GOARCH", runtime.GOARCH},
+		{"GOOS", runtime.GOOS},
+		{"GOROOT", filepath.Clean(runtime.GOROOT())},
+		{"GOPATH", os.Getenv("GOPATH")},
+		{"CgoEnabled", ""},
+		{"UseAllFiles", ""},
+		{"Compiler", ""},
+		{"BuildTags", ""},
+		{"ReleaseTags", ""},
+		{"InstallSuffix", ""},
+	} {
+		tmpl := "{{context." + tt.v + "}}"
+		tg.run("list", "-f", tmpl)
+		if tt.want == "" {
+			continue
+		}
+		if got := strings.TrimSpace(tg.getStdout()); got != tt.want {
+			t.Errorf("go list -f %q: got %q; want %q", tmpl, got, tt.want)
+		}
+	}
 }
 
 // cmd/go: "go test" should fail if package does not build
@@ -2123,7 +2163,7 @@ func TestIssue7108(t *testing.T) {
 // cmd/go: go test -a foo does not rebuild regexp.
 func TestIssue6844(t *testing.T) {
 	if testing.Short() {
-		t.Skip("don't rebuild the standard libary in short mode")
+		t.Skip("don't rebuild the standard library in short mode")
 	}
 
 	tg := testgo(t)
@@ -2295,8 +2335,7 @@ func TestGoVetWithExternalTests(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
-	tg.setenv("GOPATH", tg.path("."))
-	tg.run("get", "golang.org/x/tools/cmd/vet")
+	tg.run("install", "cmd/vet")
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.runFail("vet", "vetpkg")
 	tg.grepBoth("missing argument for Printf", "go vet vetpkg did not find missing argument for Printf")
@@ -2308,8 +2347,7 @@ func TestGoVetWithTags(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
-	tg.setenv("GOPATH", tg.path("."))
-	tg.run("get", "golang.org/x/tools/cmd/vet")
+	tg.run("install", "cmd/vet")
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.runFail("vet", "-tags", "tagtest", "vetpkg")
 	tg.grepBoth(`c\.go.*wrong number of args for format`, "go get vetpkg did not run scan tagged file")
@@ -2330,6 +2368,11 @@ func TestGoGetRscIoToolstash(t *testing.T) {
 // Issue 13037: Was not parsing <meta> tags in 404 served over HTTPS
 func TestGoGetHTTPS404(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
+	switch runtime.GOOS {
+	case "darwin", "linux", "freebsd":
+	default:
+		t.Skipf("test case does not work on %s", runtime.GOOS)
+	}
 
 	tg := testgo(t)
 	defer tg.cleanup()
@@ -2338,7 +2381,7 @@ func TestGoGetHTTPS404(t *testing.T) {
 	tg.run("get", "bazil.org/fuse/fs/fstestutil")
 }
 
-// Test that you can not import a main package.
+// Test that you cannot import a main package.
 func TestIssue4210(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
@@ -2359,6 +2402,8 @@ func TestIssue4210(t *testing.T) {
 func TestGoGetInsecure(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 
+	t.Skip("golang.org/issue/15410")
+
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
@@ -2414,22 +2459,6 @@ func TestGoGetInsecureCustomDomain(t *testing.T) {
 	tg.run("get", "-d", "-insecure", repo)
 }
 
-func TestIssue10193(t *testing.T) {
-	t.Skip("depends on code.google.com")
-	testenv.MustHaveExternalNetwork(t)
-	if _, err := exec.LookPath("hg"); err != nil {
-		t.Skip("skipping because hg binary not found")
-	}
-
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.parallel()
-	tg.tempDir("src")
-	tg.setenv("GOPATH", tg.path("."))
-	tg.runFail("get", "code.google.com/p/rsc/pdf")
-	tg.grepStderr("is shutting down", "missed warning about code.google.com")
-}
-
 func TestGoRunDirs(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
@@ -2759,3 +2788,169 @@ func TestParallelTest(t *testing.T) {
 	tg.setenv("GOPATH", tg.path("."))
 	tg.run("test", "-p=4", "p1", "p2", "p3", "p4")
 }
+
+func TestCgoConsistentResults(t *testing.T) {
+	if !canCgo {
+		t.Skip("skipping because cgo not enabled")
+	}
+	if runtime.GOOS == "solaris" {
+		// See https://golang.org/issue/13247
+		t.Skip("skipping because Solaris builds are known to be inconsistent; see #13247")
+	}
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.makeTempdir()
+	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
+	exe1 := tg.path("cgotest1" + exeSuffix)
+	exe2 := tg.path("cgotest2" + exeSuffix)
+	tg.run("build", "-o", exe1, "cgotest")
+	tg.run("build", "-x", "-o", exe2, "cgotest")
+	b1, err := ioutil.ReadFile(exe1)
+	tg.must(err)
+	b2, err := ioutil.ReadFile(exe2)
+	tg.must(err)
+
+	if !tg.doGrepMatch(`-fdebug-prefix-map=\$WORK`, &tg.stderr) {
+		t.Skip("skipping because C compiler does not support -fdebug-prefix-map")
+	}
+	if !bytes.Equal(b1, b2) {
+		t.Error("building cgotest twice did not produce the same output")
+	}
+}
+
+// Issue 14444: go get -u .../ duplicate loads errors
+func TestGoGetUpdateAllDoesNotTryToLoadDuplicates(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.makeTempdir()
+	tg.setenv("GOPATH", tg.path("."))
+	tg.run("get", "-u", ".../")
+	tg.grepStderrNot("duplicate loads of", "did not remove old packages from cache")
+}
+
+func TestFatalInBenchmarkCauseNonZeroExitStatus(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.runFail("test", "-bench", ".", "./testdata/src/benchfatal")
+	tg.grepBothNot("^ok", "test passed unexpectedly")
+	tg.grepBoth("FAIL.*benchfatal", "test did not run everything")
+}
+
+func TestBinaryOnlyPackages(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.makeTempdir()
+	tg.setenv("GOPATH", tg.path("."))
+
+	tg.tempFile("src/p1/p1.go", `//go:binary-only-package
+
+		package p1
+	`)
+	tg.wantStale("p1", "cannot access install target", "p1 is binary-only but has no binary, should be stale")
+	tg.runFail("install", "p1")
+	tg.grepStderr("missing or invalid package binary", "did not report attempt to compile binary-only package")
+
+	tg.tempFile("src/p1/p1.go", `
+		package p1
+		import "fmt"
+		func F(b bool) { fmt.Printf("hello from p1\n"); if b { F(false) } }
+	`)
+	tg.run("install", "p1")
+	os.Remove(tg.path("src/p1/p1.go"))
+	tg.mustNotExist(tg.path("src/p1/p1.go"))
+
+	tg.tempFile("src/p2/p2.go", `//go:binary-only-packages-are-not-great
+
+		package p2
+		import "p1"
+		func F() { p1.F(true) }
+	`)
+	tg.runFail("install", "p2")
+	tg.grepStderr("no buildable Go source files", "did not complain about missing sources")
+
+	tg.tempFile("src/p1/missing.go", `//go:binary-only-package
+
+		package p1
+		func G()
+	`)
+	tg.wantNotStale("p1", "no source code", "should NOT want to rebuild p1 (first)")
+	tg.run("install", "-x", "p1") // no-op, up to date
+	tg.grepBothNot("/compile", "should not have run compiler")
+	tg.run("install", "p2") // does not rebuild p1 (or else p2 will fail)
+	tg.wantNotStale("p2", "", "should NOT want to rebuild p2")
+
+	// changes to the non-source-code do not matter,
+	// and only one file needs the special comment.
+	tg.tempFile("src/p1/missing2.go", `
+		package p1
+		func H()
+	`)
+	tg.wantNotStale("p1", "no source code", "should NOT want to rebuild p1 (second)")
+	tg.wantNotStale("p2", "", "should NOT want to rebuild p2")
+
+	tg.tempFile("src/p3/p3.go", `
+		package main
+		import (
+			"p1"
+			"p2"
+		)
+		func main() {
+			p1.F(false)
+			p2.F()
+		}
+	`)
+	tg.run("install", "p3")
+
+	tg.run("run", tg.path("src/p3/p3.go"))
+	tg.grepStdout("hello from p1", "did not see message from p1")
+}
+
+// Issue 16050.
+func TestAlwaysLinkSysoFiles(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.tempDir("src/syso")
+	tg.tempFile("src/syso/a.syso", ``)
+	tg.tempFile("src/syso/b.go", `package syso`)
+	tg.setenv("GOPATH", tg.path("."))
+
+	// We should see the .syso file regardless of the setting of
+	// CGO_ENABLED.
+
+	tg.setenv("CGO_ENABLED", "1")
+	tg.run("list", "-f", "{{.SysoFiles}}", "syso")
+	tg.grepStdout("a.syso", "missing syso file with CGO_ENABLED=1")
+
+	tg.setenv("CGO_ENABLED", "0")
+	tg.run("list", "-f", "{{.SysoFiles}}", "syso")
+	tg.grepStdout("a.syso", "missing syso file with CGO_ENABLED=0")
+}
+
+// Issue 16120.
+func TestGenerateUsesBuildContext(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("this test won't run under Windows")
+	}
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.tempDir("src/gen")
+	tg.tempFile("src/gen/gen.go", "package gen\n//go:generate echo $GOOS $GOARCH\n")
+	tg.setenv("GOPATH", tg.path("."))
+
+	tg.setenv("GOOS", "linux")
+	tg.setenv("GOARCH", "amd64")
+	tg.run("generate", "gen")
+	tg.grepStdout("linux amd64", "unexpected GOOS/GOARCH combination")
+
+	tg.setenv("GOOS", "darwin")
+	tg.setenv("GOARCH", "386")
+	tg.run("generate", "gen")
+	tg.grepStdout("darwin 386", "unexpected GOOS/GOARCH combination")
+}
diff --git a/libgo/go/cmd/go/go_unix_test.go b/libgo/go/cmd/go/go_unix_test.go
index 0d85859e7e5..c445a2ec73b 100644
--- a/libgo/go/cmd/go/go_unix_test.go
+++ b/libgo/go/cmd/go/go_unix_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/help.go b/libgo/go/cmd/go/help.go
index d8e7efedb37..056a0af1125 100644
--- a/libgo/go/cmd/go/help.go
+++ b/libgo/go/cmd/go/help.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -149,14 +149,6 @@ A few common code hosting sites have special syntax:
 		import "github.com/user/project"
 		import "github.com/user/project/sub/directory"
 
-	Google Code Project Hosting (Git, Mercurial, Subversion)
-
-		import "code.google.com/p/project"
-		import "code.google.com/p/project/sub/directory"
-
-		import "code.google.com/p/project.subrepository"
-		import "code.google.com/p/project.subrepository/sub/directory"
-
 	Launchpad (Bazaar)
 
 		import "launchpad.net/project"
@@ -269,10 +261,9 @@ unless it is being referred to by that import path. In this way, import comments
 let package authors make sure the custom import path is used and not a
 direct path to the underlying code hosting site.
 
-If vendoring is enabled (see 'go help gopath'), then import path checking is
-disabled for code found within vendor trees. This makes it possible to copy
-code into alternate locations in vendor trees without needing to update import
-comments.
+Import path checking is disabled for code found within vendor trees.
+This makes it possible to copy code into alternate locations in vendor trees
+without needing to update import comments.
 
 See https://golang.org/s/go14customimport for details.
 	`,
@@ -421,12 +412,6 @@ Vendor directories do not affect the placement of new repositories
 being checked out for the first time by 'go get': those are always
 placed in the main GOPATH, never in a vendor subtree.
 
-In Go 1.5, as an experiment, setting the environment variable
-GO15VENDOREXPERIMENT=1 enabled these features.
-As of Go 1.6 they are on by default. To turn them off, set
-GO15VENDOREXPERIMENT=0. In Go 1.7, the environment
-variable will stop having any effect.
-
 See https://golang.org/s/go15vendor for details.
 	`,
 }
@@ -497,8 +482,6 @@ Special-purpose environment variables:
 		installed in a location other than where it is built.
 		File names in stack traces are rewritten from GOROOT to
 		GOROOT_FINAL.
-	GO15VENDOREXPERIMENT
-		Set to 0 to disable vendoring semantics.
 	GO_EXTLINK_ENABLED
 		Whether the linker should use external linking mode
 		when using -linkmode=auto with code that uses cgo.
@@ -540,7 +523,15 @@ the extension of the file name. These extensions are:
 Files of each of these types except .syso may contain build
 constraints, but the go command stops scanning for build constraints
 at the first item in the file that is not a blank line or //-style
-line comment.
+line comment. See the go/build package documentation for
+more details.
+
+Non-test Go source files can also include a //go:binary-only-package
+comment, indicating that the package sources are included
+for documentation only and must not be used to build the
+package binary. This enables distribution of Go packages in
+their compiled form alone. See the go/build package documentation
+for more details.
 	`,
 }
 
diff --git a/libgo/go/cmd/go/http.go b/libgo/go/cmd/go/http.go
index 3a6f19db848..05ea5030499 100644
--- a/libgo/go/cmd/go/http.go
+++ b/libgo/go/cmd/go/http.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -30,7 +30,7 @@ var httpClient = http.DefaultClient
 // when we're connecting to https servers that might not be there
 // or might be using self-signed certificates.
 var impatientInsecureHTTPClient = &http.Client{
-	Timeout: time.Duration(5 * time.Second),
+	Timeout: 5 * time.Second,
 	Transport: &http.Transport{
 		TLSClientConfig: &tls.Config{
 			InsecureSkipVerify: true,
diff --git a/libgo/go/cmd/go/list.go b/libgo/go/cmd/go/list.go
index 8f741a636b1..48678e73955 100644
--- a/libgo/go/cmd/go/list.go
+++ b/libgo/go/cmd/go/list.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -41,7 +41,10 @@ syntax of package template.  The default output is equivalent to -f
         Goroot        bool   // is this package in the Go root?
         Standard      bool   // is this package part of the standard Go library?
         Stale         bool   // would 'go install' do anything for this package?
+        StaleReason   string // explanation for Stale==true
         Root          string // Go root or Go path dir containing this package
+        ConflictDir   string // this directory shadows Dir in $GOPATH
+        BinaryOnly    bool   // binary-only package: cannot be recompiled from sources
 
         // Source files
         GoFiles        []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
@@ -51,6 +54,7 @@ syntax of package template.  The default output is equivalent to -f
         CXXFiles       []string // .cc, .cxx and .cpp source files
         MFiles         []string // .m source files
         HFiles         []string // .h, .hh, .hpp and .hxx source files
+        FFiles         []string // .f, .F, .for and .f90 Fortran source files
         SFiles         []string // .s source files
         SwigFiles      []string // .swig files
         SwigCXXFiles   []string // .swigcxx files
@@ -60,6 +64,7 @@ syntax of package template.  The default output is equivalent to -f
         CgoCFLAGS    []string // cgo: flags for C compiler
         CgoCPPFLAGS  []string // cgo: flags for C preprocessor
         CgoCXXFLAGS  []string // cgo: flags for C++ compiler
+        CgoFFLAGS    []string // cgo: flags for Fortran compiler
         CgoLDFLAGS   []string // cgo: flags for linker
         CgoPkgConfig []string // cgo: pkg-config names
 
diff --git a/libgo/go/cmd/go/main.go b/libgo/go/cmd/go/main.go
index f9b979da7fb..65ec61bd7db 100644
--- a/libgo/go/cmd/go/main.go
+++ b/libgo/go/cmd/go/main.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -214,15 +214,7 @@ var helpTemplate = `{{if .Runnable}}usage: go {{.UsageLine}}
 {{end}}{{.Long | trim}}
 `
 
-var documentationTemplate = `// Copyright 2011 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// DO NOT EDIT THIS FILE. GENERATED BY mkalldocs.sh.
-// Edit the documentation in other files and rerun mkalldocs.sh to generate this one.
-
-/*
-{{range .}}{{if .Short}}{{.Short | capitalize}}
+var documentationTemplate = `{{range .}}{{if .Short}}{{.Short | capitalize}}
 
 {{end}}{{if .Runnable}}Usage:
 
@@ -231,9 +223,39 @@ var documentationTemplate = `// Copyright 2011 The Go Authors.  All rights reser
 {{end}}{{.Long | trim}}
 
 
-{{end}}*/
-package main
-`
+{{end}}`
+
+// commentWriter writes a Go comment to the underlying io.Writer,
+// using line comment form (//).
+type commentWriter struct {
+	W            io.Writer
+	wroteSlashes bool // Wrote "//" at the beginning of the current line.
+}
+
+func (c *commentWriter) Write(p []byte) (int, error) {
+	var n int
+	for i, b := range p {
+		if !c.wroteSlashes {
+			s := "//"
+			if b != '\n' {
+				s = "// "
+			}
+			if _, err := io.WriteString(c.W, s); err != nil {
+				return n, err
+			}
+			c.wroteSlashes = true
+		}
+		n0, err := c.W.Write(p[i : i+1])
+		n += n0
+		if err != nil {
+			return n, err
+		}
+		if b == '\n' {
+			c.wroteSlashes = false
+		}
+	}
+	return len(p), nil
+}
 
 // An errWriter wraps a writer, recording whether a write error occurred.
 type errWriter struct {
@@ -310,10 +332,18 @@ func help(args []string) {
 
 	// 'go help documentation' generates doc.go.
 	if arg == "documentation" {
+		fmt.Println("// Copyright 2011 The Go Authors. All rights reserved.")
+		fmt.Println("// Use of this source code is governed by a BSD-style")
+		fmt.Println("// license that can be found in the LICENSE file.")
+		fmt.Println()
+		fmt.Println("// DO NOT EDIT THIS FILE. GENERATED BY mkalldocs.sh.")
+		fmt.Println("// Edit the documentation in other files and rerun mkalldocs.sh to generate this one.")
+		fmt.Println()
 		buf := new(bytes.Buffer)
 		printUsage(buf)
 		usage := &Command{Long: buf.String()}
-		tmpl(os.Stdout, documentationTemplate, append([]*Command{usage}, commands...))
+		tmpl(&commentWriter{W: os.Stdout}, documentationTemplate, append([]*Command{usage}, commands...))
+		fmt.Println("package main")
 		return
 	}
 
@@ -339,7 +369,7 @@ func importPathsNoDotExpansion(args []string) []string {
 	for _, a := range args {
 		// Arguments are supposed to be import paths, but
 		// as a courtesy to Windows developers, rewrite \ to /
-		// in command-line arguments.  Handles .\... and so on.
+		// in command-line arguments. Handles .\... and so on.
 		if filepath.Separator == '\\' {
 			a = strings.Replace(a, `\`, `/`, -1)
 		}
@@ -403,8 +433,6 @@ func errorf(format string, args ...interface{}) {
 	setExitStatus(1)
 }
 
-var logf = log.Printf
-
 func exitIfErrors() {
 	if exitStatus != 0 {
 		exit()
@@ -428,19 +456,6 @@ func run(cmdargs ...interface{}) {
 	}
 }
 
-func runOut(dir string, cmdargs ...interface{}) []byte {
-	cmdline := stringList(cmdargs...)
-	cmd := exec.Command(cmdline[0], cmdline[1:]...)
-	cmd.Dir = dir
-	out, err := cmd.CombinedOutput()
-	if err != nil {
-		os.Stderr.Write(out)
-		errorf("%v", err)
-		out = nil
-	}
-	return out
-}
-
 // envForDir returns a copy of the environment
 // suitable for running in the given directory.
 // The environment is the current process's environment
@@ -472,7 +487,7 @@ NextVar:
 }
 
 // matchPattern(pattern)(name) reports whether
-// name matches pattern.  Pattern is a limited glob
+// name matches pattern. Pattern is a limited glob
 // pattern in which '...' means 'any string' and there
 // is no other special syntax.
 func matchPattern(pattern string) func(name string) bool {
@@ -629,7 +644,7 @@ func matchPackages(pattern string) []string {
 
 // allPackagesInFS is like allPackages but is passed a pattern
 // beginning ./ or ../, meaning it should scan the tree rooted
-// at the given directory.  There are ... in the pattern too.
+// at the given directory. There are ... in the pattern too.
 func allPackagesInFS(pattern string) []string {
 	pkgs := matchPackagesInFS(pattern)
 	if len(pkgs) == 0 {
diff --git a/libgo/go/cmd/go/match_test.go b/libgo/go/cmd/go/match_test.go
index 38b9b115e7c..e0ad562384d 100644
--- a/libgo/go/cmd/go/match_test.go
+++ b/libgo/go/cmd/go/match_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/note.go b/libgo/go/cmd/go/note.go
index f846eeb62b1..fae9536d13f 100644
--- a/libgo/go/cmd/go/note.go
+++ b/libgo/go/cmd/go/note.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -71,7 +71,7 @@ func readELFNote(filename, name string, typ int32) ([]byte, error) {
 var elfGoNote = []byte("Go\x00\x00")
 
 // The Go build ID is stored in a note described by an ELF PT_NOTE prog
-// header.  The caller has already opened filename, to get f, and read
+// header. The caller has already opened filename, to get f, and read
 // at least 4 kB out, in data.
 func readELFGoBuildID(filename string, f *os.File, data []byte) (buildid string, err error) {
 	// Assume the note content is in the data, already read.
@@ -110,7 +110,7 @@ func readELFGoBuildID(filename string, f *os.File, data []byte) (buildid string,
 			// or even the first few megabytes of the file
 			// due to differences in note segment placement;
 			// in that case, extract the note data manually.
-			_, err = f.Seek(int64(p.Off), 0)
+			_, err = f.Seek(int64(p.Off), io.SeekStart)
 			if err != nil {
 				return "", err
 			}
diff --git a/libgo/go/cmd/go/note_test.go b/libgo/go/cmd/go/note_test.go
index 811734b3772..2ee013faf39 100644
--- a/libgo/go/cmd/go/note_test.go
+++ b/libgo/go/cmd/go/note_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -47,8 +47,6 @@ func testNoteReading(t *testing.T) {
 		t.Skipf("skipping - no cgo, so assuming external linking not available")
 	case runtime.GOOS == "linux" && (runtime.GOARCH == "ppc64le" || runtime.GOARCH == "ppc64"):
 		t.Skipf("skipping - external linking not supported, golang.org/issue/11184")
-	case runtime.GOOS == "linux" && (runtime.GOARCH == "mips64le" || runtime.GOARCH == "mips64"):
-		t.Skipf("skipping - external linking not supported, golang.org/issue/12560")
 	case runtime.GOOS == "openbsd" && runtime.GOARCH == "arm":
 		t.Skipf("skipping - external linking not supported, golang.org/issue/10619")
 	case runtime.GOOS == "plan9":
diff --git a/libgo/go/cmd/go/pkg.go b/libgo/go/cmd/go/pkg.go
index 373dade962a..6d5d97f5c07 100644
--- a/libgo/go/cmd/go/pkg.go
+++ b/libgo/go/cmd/go/pkg.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -27,8 +27,8 @@ import (
 // A Package describes a single package found in a directory.
 type Package struct {
 	// Note: These fields are part of the go command's public API.
-	// See list.go.  It is okay to add fields, but not to change or
-	// remove existing ones.  Keep in sync with list.go
+	// See list.go. It is okay to add fields, but not to change or
+	// remove existing ones. Keep in sync with list.go
 	Dir           string `json:",omitempty"` // directory containing package sources
 	ImportPath    string `json:",omitempty"` // import path of package in dir
 	ImportComment string `json:",omitempty"` // path in import comment on package statement
@@ -39,8 +39,10 @@ type Package struct {
 	Goroot        bool   `json:",omitempty"` // is this package found in the Go root?
 	Standard      bool   `json:",omitempty"` // is this package part of the standard Go library?
 	Stale         bool   `json:",omitempty"` // would 'go install' do anything for this package?
+	StaleReason   string `json:",omitempty"` // why is Stale true?
 	Root          string `json:",omitempty"` // Go root or Go path dir containing this package
 	ConflictDir   string `json:",omitempty"` // Dir is hidden by this other directory
+	BinaryOnly    bool   `json:",omitempty"` // package cannot be recompiled
 
 	// Source files
 	GoFiles        []string `json:",omitempty"` // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
@@ -50,6 +52,7 @@ type Package struct {
 	CXXFiles       []string `json:",omitempty"` // .cc, .cpp and .cxx source files
 	MFiles         []string `json:",omitempty"` // .m source files
 	HFiles         []string `json:",omitempty"` // .h, .hh, .hpp and .hxx source files
+	FFiles         []string `json:",omitempty"` // .f, .F, .for and .f90 Fortran source files
 	SFiles         []string `json:",omitempty"` // .s source files
 	SwigFiles      []string `json:",omitempty"` // .swig files
 	SwigCXXFiles   []string `json:",omitempty"` // .swigcxx files
@@ -59,6 +62,7 @@ type Package struct {
 	CgoCFLAGS    []string `json:",omitempty"` // cgo: flags for C compiler
 	CgoCPPFLAGS  []string `json:",omitempty"` // cgo: flags for C preprocessor
 	CgoCXXFLAGS  []string `json:",omitempty"` // cgo: flags for C++ compiler
+	CgoFFLAGS    []string `json:",omitempty"` // cgo: flags for Fortran compiler
 	CgoLDFLAGS   []string `json:",omitempty"` // cgo: flags for linker
 	CgoPkgConfig []string `json:",omitempty"` // cgo: pkg-config names
 
@@ -88,7 +92,6 @@ type Package struct {
 	target       string               // installed file for this package (may be executable)
 	fake         bool                 // synthesized package
 	external     bool                 // synthesized external test package
-	forceBuild   bool                 // this package must be rebuilt
 	forceLibrary bool                 // this package is a library (even if named "main")
 	cmdline      bool                 // defined by files listed on command line
 	local        bool                 // imported via local path (./ or ../)
@@ -151,6 +154,8 @@ func (p *Package) copyBuild(pp *build.Package) {
 	p.Doc = pp.Doc
 	p.Root = pp.Root
 	p.ConflictDir = pp.ConflictDir
+	p.BinaryOnly = pp.BinaryOnly
+
 	// TODO? Target
 	p.Goroot = pp.Goroot
 	if buildContext.Compiler == "gccgo" {
@@ -165,6 +170,7 @@ func (p *Package) copyBuild(pp *build.Package) {
 	p.CXXFiles = pp.CXXFiles
 	p.MFiles = pp.MFiles
 	p.HFiles = pp.HFiles
+	p.FFiles = pp.FFiles
 	p.SFiles = pp.SFiles
 	p.SwigFiles = pp.SwigFiles
 	p.SwigCXXFiles = pp.SwigCXXFiles
@@ -209,7 +215,7 @@ func (p *PackageError) Error() string {
 		return fmt.Sprintf("%s\npackage %s\n", p.Err, strings.Join(p.ImportStack, "\n\timports "))
 	}
 	if p.Pos != "" {
-		// Omit import stack.  The full path to the file where the error
+		// Omit import stack. The full path to the file where the error
 		// is the most important thing.
 		return p.Pos + ": " + p.Err
 	}
@@ -267,18 +273,9 @@ func reloadPackage(arg string, stk *importStack) *Package {
 	return loadPackage(arg, stk)
 }
 
-// The Go 1.5 vendoring experiment was enabled by setting GO15VENDOREXPERIMENT=1.
-// In Go 1.6 this is on by default and is disabled by setting GO15VENDOREXPERIMENT=0.
-// In Go 1.7 the variable will stop having any effect.
-// The variable is obnoxiously long so that years from now when people find it in
-// their profiles and wonder what it does, there is some chance that a web search
-// might answer the question.
-// There is a copy of this variable in src/go/build/build.go. Delete that one when this one goes away.
-var go15VendorExperiment = os.Getenv("GO15VENDOREXPERIMENT") != "0"
-
 // dirToImportPath returns the pseudo-import path we use for a package
-// outside the Go path.  It begins with _/ and then contains the full path
-// to the directory.  If the package lives in c:\home\gopher\my\pkg then
+// outside the Go path. It begins with _/ and then contains the full path
+// to the directory. If the package lives in c:\home\gopher\my\pkg then
 // the pseudo-import path is _/c_/home/gopher/my/pkg.
 // Using a pseudo-import path like this makes the ./ imports no longer
 // a special case, so that all the code to deal with ordinary imports works
@@ -365,7 +362,7 @@ func loadImport(path, srcDir string, parent *Package, stk *importStack, importPo
 	// TODO: After Go 1, decide when to pass build.AllowBinary here.
 	// See issue 3268 for mistakes to avoid.
 	buildMode := build.ImportComment
-	if !go15VendorExperiment || mode&useVendor == 0 || path != origPath {
+	if mode&useVendor == 0 || path != origPath {
 		// Not vendoring, or we already found the vendored path.
 		buildMode |= build.IgnoreVendor
 	}
@@ -375,7 +372,7 @@ func loadImport(path, srcDir string, parent *Package, stk *importStack, importPo
 		bp.BinDir = gobin
 	}
 	if err == nil && !isLocal && bp.ImportComment != "" && bp.ImportComment != path &&
-		(!go15VendorExperiment || (!strings.Contains(path, "/vendor/") && !strings.HasPrefix(path, "vendor/"))) {
+		!strings.Contains(path, "/vendor/") && !strings.HasPrefix(path, "vendor/") {
 		err = fmt.Errorf("code in directory %s expects import %q", bp.Dir, bp.ImportComment)
 	}
 	p.load(stk, bp, err)
@@ -416,7 +413,7 @@ func isDir(path string) bool {
 // x/vendor/path, vendor/path, or else stay path if none of those exist.
 // vendoredImportPath returns the expanded path or, if no expansion is found, the original.
 func vendoredImportPath(parent *Package, path string) (found string) {
-	if parent == nil || parent.Root == "" || !go15VendorExperiment {
+	if parent == nil || parent.Root == "" {
 		return path
 	}
 
@@ -445,6 +442,12 @@ func vendoredImportPath(parent *Package, path string) (found string) {
 		}
 		targ := filepath.Join(dir[:i], vpath)
 		if isDir(targ) && hasGoFiles(targ) {
+			importPath := parent.ImportPath
+			if importPath == "command-line-arguments" {
+				// If parent.ImportPath is 'command-line-arguments'.
+				// set to relative directory to root (also chopped root directory)
+				importPath = dir[len(root)+1:]
+			}
 			// We started with parent's dir c:\gopath\src\foo\bar\baz\quux\xyzzy.
 			// We know the import path for parent's dir.
 			// We chopped off some number of path elements and
@@ -454,14 +457,14 @@ func vendoredImportPath(parent *Package, path string) (found string) {
 			// (actually the same number of bytes) from parent's import path
 			// and then append /vendor/path.
 			chopped := len(dir) - i
-			if chopped == len(parent.ImportPath)+1 {
+			if chopped == len(importPath)+1 {
 				// We walked up from c:\gopath\src\foo\bar
 				// and found c:\gopath\src\vendor\path.
 				// We chopped \foo\bar (length 8) but the import path is "foo/bar" (length 7).
 				// Use "vendor/path" without any prefix.
 				return vpath
 			}
-			return parent.ImportPath[:len(parent.ImportPath)-chopped] + "/" + vpath
+			return importPath[:len(importPath)-chopped] + "/" + vpath
 		}
 	}
 	return path
@@ -482,7 +485,7 @@ func hasGoFiles(dir string) bool {
 }
 
 // reusePackage reuses package p to satisfy the import at the top
-// of the import stack stk.  If this use causes an import loop,
+// of the import stack stk. If this use causes an import loop,
 // reusePackage updates p's error information to record the loop.
 func reusePackage(p *Package, stk *importStack) *Package {
 	// We use p.imports==nil to detect a package that
@@ -528,7 +531,7 @@ func disallowInternal(srcDir string, p *Package, stk *importStack) *Package {
 		return p
 	}
 
-	// Check for "internal" element: four cases depending on begin of string and/or end of string.
+	// Check for "internal" element: three cases depending on begin of string and/or end of string.
 	i, ok := findInternal(p.ImportPath)
 	if !ok {
 		return p
@@ -565,7 +568,7 @@ func disallowInternal(srcDir string, p *Package, stk *importStack) *Package {
 // If there isn't one, findInternal returns ok=false.
 // Otherwise, findInternal returns ok=true and the index of the "internal".
 func findInternal(path string) (index int, ok bool) {
-	// Four cases, depending on internal at start/end of string or not.
+	// Three cases, depending on internal at start/end of string or not.
 	// The order matters: we must return the index of the final element,
 	// because the final one produces the most restrictive requirement
 	// on the importer.
@@ -584,10 +587,6 @@ func findInternal(path string) (index int, ok bool) {
 // If the import is allowed, disallowVendor returns the original package p.
 // If not, it returns a new package containing just an appropriate error.
 func disallowVendor(srcDir, path string, p *Package, stk *importStack) *Package {
-	if !go15VendorExperiment {
-		return p
-	}
-
 	// The stack includes p.ImportPath.
 	// If that's the only thing on the stack, we started
 	// with a name given on the command line, not an
@@ -667,7 +666,7 @@ func disallowVendorVisibility(srcDir string, p *Package, stk *importStack) *Pack
 
 // findVendor looks for the last non-terminating "vendor" path element in the given import path.
 // If there isn't one, findVendor returns ok=false.
-// Otherwise, findInternal returns ok=true and the index of the "vendor".
+// Otherwise, findVendor returns ok=true and the index of the "vendor".
 //
 // Note that terminating "vendor" elements don't count: "x/vendor" is its own package,
 // not the vendored copy of an import "" (the empty import path).
@@ -691,7 +690,6 @@ type targetDir int
 const (
 	toRoot    targetDir = iota // to bin dir inside package root (default)
 	toTool                     // GOROOT/pkg/tool
-	toBin                      // GOROOT/bin
 	stalePath                  // the old import path; fail to build
 )
 
@@ -715,7 +713,6 @@ var goTools = map[string]targetDir{
 	"cmd/trace":                            toTool,
 	"cmd/vet":                              toTool,
 	"cmd/yacc":                             toTool,
-	"golang.org/x/tools/cmd/godoc":         toBin,
 	"code.google.com/p/go.tools/cmd/cover": stalePath,
 	"code.google.com/p/go.tools/cmd/godoc": stalePath,
 	"code.google.com/p/go.tools/cmd/vet":   stalePath,
@@ -729,7 +726,7 @@ func expandScanner(err error) error {
 		// Prepare error with \n before each message.
 		// When printed in something like context: %v
 		// this will put the leading file positions each on
-		// its own line.  It will also show all the errors
+		// its own line. It will also show all the errors
 		// instead of just the first, as err.Error does.
 		var buf bytes.Buffer
 		for _, e := range err {
@@ -802,12 +799,7 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 			// Install cross-compiled binaries to subdirectories of bin.
 			elem = full
 		}
-		if p.build.BinDir != gobin && goTools[p.ImportPath] == toBin {
-			// Override BinDir.
-			// This is from a subrepo but installs to $GOROOT/bin
-			// by default anyway (like godoc).
-			p.target = filepath.Join(gorootBin, elem)
-		} else if p.build.BinDir != "" {
+		if p.build.BinDir != "" {
 			// Install to GOBIN or bin of GOPATH entry.
 			p.target = filepath.Join(p.build.BinDir, elem)
 			if !p.Goroot && strings.Contains(elem, "/") && gobin != "" {
@@ -930,6 +922,7 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 		p.CXXFiles,
 		p.MFiles,
 		p.HFiles,
+		p.FFiles,
 		p.SFiles,
 		p.SysoFiles,
 		p.SwigFiles,
@@ -1032,6 +1025,20 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 	}
 	p.Target = p.target
 
+	// If cgo is not enabled, ignore cgo supporting sources
+	// just as we ignore go files containing import "C".
+	if !buildContext.CgoEnabled {
+		p.CFiles = nil
+		p.CXXFiles = nil
+		p.MFiles = nil
+		p.SwigFiles = nil
+		p.SwigCXXFiles = nil
+		// Note that SFiles are okay (they go to the Go assembler)
+		// and HFiles are okay (they might be used by the SFiles).
+		// Also Sysofiles are okay (they might not contain object
+		// code; see issue #16050).
+	}
+
 	// The gc toolchain only permits C source files with cgo.
 	if len(p.CFiles) > 0 && !p.usesCgo() && !p.usesSwig() && buildContext.Compiler == "gc" {
 		p.Error = &PackageError{
@@ -1054,7 +1061,15 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 		}
 	}
 
-	computeBuildID(p)
+	if p.BinaryOnly {
+		// For binary-only package, use build ID from supplied package binary.
+		buildID, err := readBuildID(p)
+		if err == nil {
+			p.buildID = buildID
+		}
+	} else {
+		computeBuildID(p)
+	}
 	return p
 }
 
@@ -1094,7 +1109,7 @@ func packageList(roots []*Package) []*Package {
 // at the named pkgs (command-line arguments).
 func computeStale(pkgs ...*Package) {
 	for _, p := range packageList(pkgs) {
-		p.Stale = isStale(p)
+		p.Stale, p.StaleReason = isStale(p)
 	}
 }
 
@@ -1240,7 +1255,7 @@ var isGoRelease = strings.HasPrefix(runtime.Version(), "go1")
 // an explicit data comparison. Specifically, we build a list of the
 // inputs to the build, compute its SHA1 hash, and record that as the
 // ``build ID'' in the generated object. At the next build, we can
-// recompute the buid ID and compare it to the one in the generated
+// recompute the build ID and compare it to the one in the generated
 // object. If they differ, the list of inputs has changed, so the object
 // is out of date and must be rebuilt.
 //
@@ -1365,40 +1380,50 @@ var isGoRelease = strings.HasPrefix(runtime.Version(), "go1")
 // standard library, even in release versions. This makes
 // 'go build -tags netgo' work, among other things.
 
-// isStale reports whether package p needs to be rebuilt.
-func isStale(p *Package) bool {
+// isStale reports whether package p needs to be rebuilt,
+// along with the reason why.
+func isStale(p *Package) (bool, string) {
 	if p.Standard && (p.ImportPath == "unsafe" || buildContext.Compiler == "gccgo") {
 		// fake, builtin package
-		return false
+		return false, "builtin package"
 	}
 	if p.Error != nil {
-		return true
+		return true, "errors loading package"
+	}
+	if p.Stale {
+		return true, p.StaleReason
 	}
 
-	// A package without Go sources means we only found
-	// the installed .a file.  Since we don't know how to rebuild
-	// it, it can't be stale, even if -a is set.  This enables binary-only
-	// distributions of Go packages, although such binaries are
-	// only useful with the specific version of the toolchain that
-	// created them.
-	if len(p.gofiles) == 0 && !p.usesSwig() {
-		return false
+	// If this is a package with no source code, it cannot be rebuilt.
+	// If the binary is missing, we mark the package stale so that
+	// if a rebuild is needed, that rebuild attempt will produce a useful error.
+	// (Some commands, such as 'go list', do not attempt to rebuild.)
+	if p.BinaryOnly {
+		if p.target == "" {
+			// Fail if a build is attempted.
+			return true, "no source code for package, but no install target"
+		}
+		if _, err := os.Stat(p.target); err != nil {
+			// Fail if a build is attempted.
+			return true, "no source code for package, but cannot access install target: " + err.Error()
+		}
+		return false, "no source code for package"
 	}
 
 	// If the -a flag is given, rebuild everything.
 	if buildA {
-		return true
+		return true, "build -a flag in use"
 	}
 
-	// If there's no install target or it's already marked stale, we have to rebuild.
-	if p.target == "" || p.Stale {
-		return true
+	// If there's no install target, we have to rebuild.
+	if p.target == "" {
+		return true, "no install target"
 	}
 
 	// Package is stale if completely unbuilt.
 	fi, err := os.Stat(p.target)
 	if err != nil {
-		return true
+		return true, "cannot stat install target"
 	}
 
 	// Package is stale if the expected build ID differs from the
@@ -1411,13 +1436,13 @@ func isStale(p *Package) bool {
 	// See issue 8290 and issue 10702.
 	targetBuildID, err := readBuildID(p)
 	if err == nil && targetBuildID != p.buildID {
-		return true
+		return true, "build ID mismatch"
 	}
 
 	// Package is stale if a dependency is.
 	for _, p1 := range p.deps {
 		if p1.Stale {
-			return true
+			return true, "stale dependency"
 		}
 	}
 
@@ -1440,7 +1465,7 @@ func isStale(p *Package) bool {
 	// install is to run make.bash, which will remove the old package archives
 	// before rebuilding.)
 	if p.Standard && isGoRelease {
-		return false
+		return false, "standard package in Go release distribution"
 	}
 
 	// Time-based staleness.
@@ -1455,14 +1480,14 @@ func isStale(p *Package) bool {
 	// Package is stale if a dependency is, or if a dependency is newer.
 	for _, p1 := range p.deps {
 		if p1.target != "" && olderThan(p1.target) {
-			return true
+			return true, "newer dependency"
 		}
 	}
 
 	// As a courtesy to developers installing new versions of the compiler
 	// frequently, define that packages are stale if they are
 	// older than the compiler, and commands if they are older than
-	// the linker.  This heuristic will not work if the binaries are
+	// the linker. This heuristic will not work if the binaries are
 	// back-dated, as some binary distributions may do, but it does handle
 	// a very common case.
 	// See issue 3036.
@@ -1474,10 +1499,10 @@ func isStale(p *Package) bool {
 	// taken care of above (at least when the installed Go is a released version).
 	if p.Root != goroot {
 		if olderThan(buildToolchain.compiler()) {
-			return true
+			return true, "newer compiler"
 		}
 		if p.build.IsCommand() && olderThan(buildToolchain.linker()) {
-			return true
+			return true, "newer linker"
 		}
 	}
 
@@ -1519,14 +1544,14 @@ func isStale(p *Package) bool {
 	// to test for write access, and then skip GOPATH roots we don't have write
 	// access to. But hopefully we can just use the mtimes always.
 
-	srcs := stringList(p.GoFiles, p.CFiles, p.CXXFiles, p.MFiles, p.HFiles, p.SFiles, p.CgoFiles, p.SysoFiles, p.SwigFiles, p.SwigCXXFiles)
+	srcs := stringList(p.GoFiles, p.CFiles, p.CXXFiles, p.MFiles, p.HFiles, p.FFiles, p.SFiles, p.CgoFiles, p.SysoFiles, p.SwigFiles, p.SwigCXXFiles)
 	for _, src := range srcs {
 		if olderThan(filepath.Join(p.Dir, src)) {
-			return true
+			return true, "newer source file"
 		}
 	}
 
-	return false
+	return false, ""
 }
 
 // computeBuildID computes the build ID for p, leaving it in p.buildID.
@@ -1584,7 +1609,7 @@ var cwd, _ = os.Getwd()
 var cmdCache = map[string]*Package{}
 
 // loadPackage is like loadImport but is used for command-line arguments,
-// not for paths found in import statements.  In addition to ordinary import paths,
+// not for paths found in import statements. In addition to ordinary import paths,
 // loadPackage accepts pseudo-paths beginning with cmd/ to denote commands
 // in the Go command directory, as well as paths to those directories.
 func loadPackage(arg string, stk *importStack) *Package {
@@ -1648,7 +1673,7 @@ func loadPackage(arg string, stk *importStack) *Package {
 // command line arguments 'args'.  If a named package
 // cannot be loaded at all (for example, if the directory does not exist),
 // then packages prints an error and does not include that
-// package in the results.  However, if errors occur trying
+// package in the results. However, if errors occur trying
 // to load dependencies of a named package, the named
 // package is still returned, with p.Incomplete = true
 // and details in p.DepsErrors.
diff --git a/libgo/go/cmd/go/pkg_test.go b/libgo/go/cmd/go/pkg_test.go
index 1e7ca2c6fe0..fba13636cdd 100644
--- a/libgo/go/cmd/go/pkg_test.go
+++ b/libgo/go/cmd/go/pkg_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -161,9 +161,12 @@ func TestSharedLibName(t *testing.T) {
 				}
 				oldGopath := buildContext.GOPATH
 				defer func() {
-					os.RemoveAll(tmpGopath)
 					buildContext.GOPATH = oldGopath
 					os.Chdir(cwd)
+					err := os.RemoveAll(tmpGopath)
+					if err != nil {
+						t.Error(err)
+					}
 				}()
 				root := filepath.Join(tmpGopath, "src", data.rootedAt)
 				err = os.MkdirAll(root, 0755)
diff --git a/libgo/go/cmd/go/run.go b/libgo/go/cmd/go/run.go
index bf10f4f3e91..18387b5eafa 100644
--- a/libgo/go/cmd/go/run.go
+++ b/libgo/go/cmd/go/run.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -128,7 +128,7 @@ func runRun(cmd *Command, args []string) {
 }
 
 // runProgram is the action for running a binary that has already
-// been compiled.  We ignore exit status.
+// been compiled. We ignore exit status.
 func (b *builder) runProgram(a *action) error {
 	cmdline := stringList(findExecCmd(), a.deps[0].target, a.args)
 	if buildN || buildX {
diff --git a/libgo/go/cmd/go/tag_test.go b/libgo/go/cmd/go/tag_test.go
index ffe218c7b6d..6649bd61952 100644
--- a/libgo/go/cmd/go/tag_test.go
+++ b/libgo/go/cmd/go/tag_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/test.go b/libgo/go/cmd/go/test.go
index 1cf58920589..1de915a2533 100644
--- a/libgo/go/cmd/go/test.go
+++ b/libgo/go/cmd/go/test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -59,6 +59,9 @@ Each listed package causes the execution of a separate test binary.
 Test files that declare a package with the suffix "_test" will be compiled as a
 separate package, and then linked and run with the main test binary.
 
+The go tool will ignore a directory named "testdata", making it available
+to hold ancillary data needed by the tests.
+
 By default, go test needs no arguments.  It compiles and tests the package
 with source in the current directory, including tests, and runs the tests.
 
@@ -125,7 +128,10 @@ control the execution of any test:
 
 const testFlag2 = `
 	-bench regexp
-	    Run benchmarks matching the regular expression.
+	    Run (sub)benchmarks matching a regular expression.
+	    The given regular expression is split into smaller ones by
+	    top-level '/', where each must match the corresponding part of a
+	    benchmark's identifier.
 	    By default, no benchmarks run. To run all benchmarks,
 	    use '-bench .' or '-bench=.'.
 
@@ -213,8 +219,10 @@ const testFlag2 = `
 	    (see 'go help build').
 
 	-run regexp
-	    Run only those tests and examples matching the regular
-	    expression.
+	    Run only those tests and examples matching the regular expression.
+	    For tests the regular expression is split into smaller ones by
+	    top-level '/', where each must match the corresponding part of a
+	    test's identifier.
 
 	-short
 	    Tell long-running tests to shorten their run time.
@@ -228,7 +236,6 @@ const testFlag2 = `
 
 	-trace trace.out
 	    Write an execution trace to the specified file before exiting.
-	    Writes test binary as -c would.
 
 	-v
 	    Verbose output: log all tests as they are run. Also print all
@@ -256,7 +263,7 @@ execution, not to the test itself.)
 The test flags that generate profiles (other than for coverage) also
 leave the test binary in pkg.test for use when analyzing the profiles.
 
-When 'go test' runs a test binary, it does so from within the 
+When 'go test' runs a test binary, it does so from within the
 corresponding package's source code directory. Depending on the test,
 it may be necessary to do the same when invoking a generated test
 binary directly.
@@ -311,10 +318,11 @@ A benchmark function is one named BenchmarkXXX and should have the signature,
 
 An example function is similar to a test function but, instead of using
 *testing.T to report success or failure, prints output to os.Stdout.
-That output is compared against the function's "Output:" comment, which
-must be the last comment in the function body (see example below). An
-example with no such comment, or with no text after "Output:" is compiled
-but not executed.
+If the last comment in the function starts with "Output:" then the output
+is compared exactly against the comment (see examples below). If the last
+comment begins with "Unordered output:" then the output is compared to the
+comment, however the order of the lines is ignored. An example with no such
+comment, or with no text after "Output:" is compiled but not executed.
 
 Godoc displays the body of ExampleXXX to demonstrate the use
 of the function, constant, or variable XXX.  An example of a method M with
@@ -330,6 +338,20 @@ Here is an example of an example:
 		// this example.
 	}
 
+Here is another example where the ordering of the output is ignored:
+
+	func ExamplePerm() {
+		for _, value := range Perm(4) {
+			fmt.Println(value)
+		}
+
+		// Unordered output: 4
+		// 2
+		// 1
+		// 3
+		// 0
+	}
+
 The entire test file is presented as the example when it contains a single
 example function, at least one other function, type, variable, or constant
 declaration, and no test or benchmark functions.
@@ -388,7 +410,7 @@ func runTest(cmd *Command, args []string) {
 	}
 
 	// If a test timeout was given and is parseable, set our kill timeout
-	// to that timeout plus one minute.  This is a backup alarm in case
+	// to that timeout plus one minute. This is a backup alarm in case
 	// the test wedges with a goroutine spinning and its background
 	// timer does not get a chance to fire.
 	if dt, err := time.ParseDuration(testTimeout); err == nil && dt > 0 {
@@ -495,7 +517,8 @@ func runTest(cmd *Command, args []string) {
 				continue
 			}
 			p.Stale = true // rebuild
-			p.fake = true  // do not warn about rebuild
+			p.StaleReason = "rebuild for coverage"
+			p.fake = true // do not warn about rebuild
 			p.coverMode = testCoverMode
 			var coverFiles []string
 			coverFiles = append(coverFiles, p.GoFiles...)
@@ -700,7 +723,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 	// the usual place in the temporary tree, because then
 	// other tests will see it as the real package.
 	// Instead we make a _test directory under the import path
-	// and then repeat the import path there.  We tell the
+	// and then repeat the import path there. We tell the
 	// compiler and linker to look in that _test directory first.
 	//
 	// That is, if the package under test is unicode/utf8,
@@ -738,6 +761,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 		ptest.fake = true
 		ptest.forceLibrary = true
 		ptest.Stale = true
+		ptest.StaleReason = "rebuild for test"
 		ptest.build = new(build.Package)
 		*ptest.build = *p.build
 		m := map[string][]token.Position{}
@@ -1019,6 +1043,7 @@ func recompileForTest(pmain, preal, ptest *Package, testDir string) {
 				p.target = ""
 				p.fake = true
 				p.Stale = true
+				p.StaleReason = "depends on package being tested"
 			}
 		}
 
@@ -1218,11 +1243,11 @@ func (b *builder) notest(a *action) error {
 	return nil
 }
 
-// isTestMain tells whether fn is a TestMain(m *testing.M) function.
-func isTestMain(fn *ast.FuncDecl) bool {
-	if fn.Name.String() != "TestMain" ||
-		fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
-		fn.Type.Params == nil ||
+// isTestFunc tells whether fn has the type of a testing function. arg
+// specifies the parameter type we look for: B, M or T.
+func isTestFunc(fn *ast.FuncDecl, arg string) bool {
+	if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
+		fn.Type.Params.List == nil ||
 		len(fn.Type.Params.List) != 1 ||
 		len(fn.Type.Params.List[0].Names) > 1 {
 		return false
@@ -1234,10 +1259,11 @@ func isTestMain(fn *ast.FuncDecl) bool {
 	// We can't easily check that the type is *testing.M
 	// because we don't know how testing has been imported,
 	// but at least check that it's *M or *something.M.
-	if name, ok := ptr.X.(*ast.Ident); ok && name.Name == "M" {
+	// Same applies for B and T.
+	if name, ok := ptr.X.(*ast.Ident); ok && name.Name == arg {
 		return true
 	}
-	if sel, ok := ptr.X.(*ast.SelectorExpr); ok && sel.Sel.Name == "M" {
+	if sel, ok := ptr.X.(*ast.SelectorExpr); ok && sel.Sel.Name == arg {
 		return true
 	}
 	return false
@@ -1334,9 +1360,10 @@ func (t *testFuncs) Tested() string {
 }
 
 type testFunc struct {
-	Package string // imported package name (_test or _xtest)
-	Name    string // function name
-	Output  string // output, for examples
+	Package   string // imported package name (_test or _xtest)
+	Name      string // function name
+	Output    string // output, for examples
+	Unordered bool   // output is allowed to be unordered.
 }
 
 var testFileSet = token.NewFileSet()
@@ -1356,17 +1383,25 @@ func (t *testFuncs) load(filename, pkg string, doImport, seen *bool) error {
 		}
 		name := n.Name.String()
 		switch {
-		case isTestMain(n):
+		case name == "TestMain" && isTestFunc(n, "M"):
 			if t.TestMain != nil {
 				return errors.New("multiple definitions of TestMain")
 			}
-			t.TestMain = &testFunc{pkg, name, ""}
+			t.TestMain = &testFunc{pkg, name, "", false}
 			*doImport, *seen = true, true
 		case isTest(name, "Test"):
-			t.Tests = append(t.Tests, testFunc{pkg, name, ""})
+			err := checkTestFunc(n, "T")
+			if err != nil {
+				return err
+			}
+			t.Tests = append(t.Tests, testFunc{pkg, name, "", false})
 			*doImport, *seen = true, true
 		case isTest(name, "Benchmark"):
-			t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, ""})
+			err := checkTestFunc(n, "B")
+			if err != nil {
+				return err
+			}
+			t.Benchmarks = append(t.Benchmarks, testFunc{pkg, name, "", false})
 			*doImport, *seen = true, true
 		}
 	}
@@ -1378,12 +1413,21 @@ func (t *testFuncs) load(filename, pkg string, doImport, seen *bool) error {
 			// Don't run examples with no output.
 			continue
 		}
-		t.Examples = append(t.Examples, testFunc{pkg, "Example" + e.Name, e.Output})
+		t.Examples = append(t.Examples, testFunc{pkg, "Example" + e.Name, e.Output, e.Unordered})
 		*seen = true
 	}
 	return nil
 }
 
+func checkTestFunc(fn *ast.FuncDecl, arg string) error {
+	if !isTestFunc(fn, arg) {
+		name := fn.Name.String()
+		pos := testFileSet.Position(fn.Pos())
+		return fmt.Errorf("%s: wrong signature for %s, must be: func %s(%s *testing.%s)", pos, name, name, strings.ToLower(arg), arg)
+	}
+	return nil
+}
+
 type byOrder []*doc.Example
 
 func (x byOrder) Len() int           { return len(x) }
@@ -1429,7 +1473,7 @@ var benchmarks = []testing.InternalBenchmark{
 
 var examples = []testing.InternalExample{
 {{range .Examples}}
-	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}},
+	{"{{.Name}}", {{.Package}}.{{.Name}}, {{.Output | printf "%q"}}, {{.Unordered}}},
 {{end}}
 }
 
diff --git a/libgo/go/cmd/go/testdata/dep_test.go b/libgo/go/cmd/go/testdata/dep_test.go
index 0c53ac4f963..ac39a5bb1c2 100644
--- a/libgo/go/cmd/go/testdata/dep_test.go
+++ b/libgo/go/cmd/go/testdata/dep_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/example1_test.go b/libgo/go/cmd/go/testdata/example1_test.go
index ec7092e972b..87e6c0acfaa 100644
--- a/libgo/go/cmd/go/testdata/example1_test.go
+++ b/libgo/go/cmd/go/testdata/example1_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/example2_test.go b/libgo/go/cmd/go/testdata/example2_test.go
index 1e0e80b80f0..5d134260051 100644
--- a/libgo/go/cmd/go/testdata/example2_test.go
+++ b/libgo/go/cmd/go/testdata/example2_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/generate/test1.go b/libgo/go/cmd/go/testdata/generate/test1.go
index 1f05734f04f..168cfb74fbf 100644
--- a/libgo/go/cmd/go/testdata/generate/test1.go
+++ b/libgo/go/cmd/go/testdata/generate/test1.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/generate/test2.go b/libgo/go/cmd/go/testdata/generate/test2.go
index ef1a3d95159..829244a1663 100644
--- a/libgo/go/cmd/go/testdata/generate/test2.go
+++ b/libgo/go/cmd/go/testdata/generate/test2.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/generate/test3.go b/libgo/go/cmd/go/testdata/generate/test3.go
index 3d6a8a5c742..e950da591a7 100644
--- a/libgo/go/cmd/go/testdata/generate/test3.go
+++ b/libgo/go/cmd/go/testdata/generate/test3.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/generate/test4.go b/libgo/go/cmd/go/testdata/generate/test4.go
index a7631c4a456..6dae0486eb4 100644
--- a/libgo/go/cmd/go/testdata/generate/test4.go
+++ b/libgo/go/cmd/go/testdata/generate/test4.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/testdata/src/benchfatal/x_test.go b/libgo/go/cmd/go/testdata/src/benchfatal/x_test.go
new file mode 100644
index 00000000000..8d3a5deced8
--- /dev/null
+++ b/libgo/go/cmd/go/testdata/src/benchfatal/x_test.go
@@ -0,0 +1,7 @@
+package benchfatal
+
+import "testing"
+
+func BenchmarkThatCallsFatal(b *testing.B) {
+	b.Fatal("called by benchmark")
+}
diff --git a/libgo/go/cmd/go/testflag.go b/libgo/go/cmd/go/testflag.go
index 873df1ffc36..a65ed1f3840 100644
--- a/libgo/go/cmd/go/testflag.go
+++ b/libgo/go/cmd/go/testflag.go
@@ -149,9 +149,11 @@ func testFlags(args []string) (packageNames, passToTest []string) {
 				testBench = true
 			case "timeout":
 				testTimeout = value
-			case "blockprofile", "cpuprofile", "memprofile", "trace":
+			case "blockprofile", "cpuprofile", "memprofile":
 				testProfile = true
 				testNeedBinary = true
+			case "trace":
+				testProfile = true
 			case "coverpkg":
 				testCover = true
 				if value == "" {
diff --git a/libgo/go/cmd/go/testgo.go b/libgo/go/cmd/go/testgo.go
index 01923f74bdf..e507f34be69 100644
--- a/libgo/go/cmd/go/testgo.go
+++ b/libgo/go/cmd/go/testgo.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/tool.go b/libgo/go/cmd/go/tool.go
index 9a552d6ec01..65bf1ff33b0 100644
--- a/libgo/go/cmd/go/tool.go
+++ b/libgo/go/cmd/go/tool.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/vcs.go b/libgo/go/cmd/go/vcs.go
index 342edee50d9..53ddbe694ee 100644
--- a/libgo/go/cmd/go/vcs.go
+++ b/libgo/go/cmd/go/vcs.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -93,7 +93,7 @@ var vcsHg = &vcsCmd{
 	downloadCmd: []string{"pull"},
 
 	// We allow both tag and branch names as 'tags'
-	// for selecting a version.  This lets people have
+	// for selecting a version. This lets people have
 	// a go.release.r60 branch and a go1 branch
 	// and make changes in both, without constantly
 	// editing .hgtags.
@@ -171,10 +171,10 @@ func gitRemoteRepo(vcsGit *vcsCmd, rootDir string) (remoteRepo string, err error
 		// Eg, "git@github.com:user/repo" becomes
 		// "ssh://git@github.com/user/repo".
 		repoURL = &url.URL{
-			Scheme:  "ssh",
-			User:    url.User(m[1]),
-			Host:    m[2],
-			RawPath: m[3],
+			Scheme: "ssh",
+			User:   url.User(m[1]),
+			Host:   m[2],
+			Path:   m[3],
 		}
 	} else {
 		repoURL, err = url.Parse(out)
@@ -253,7 +253,7 @@ func bzrResolveRepo(vcsBzr *vcsCmd, rootDir, remoteRepo string) (realRepo string
 		return "", fmt.Errorf("unable to parse output of bzr info")
 	}
 	out = out[:i]
-	return strings.TrimSpace(string(out)), nil
+	return strings.TrimSpace(out), nil
 }
 
 // vcsSvn describes how to use Subversion.
@@ -294,7 +294,7 @@ func svnRemoteRepo(vcsSvn *vcsCmd, rootDir string) (remoteRepo string, err error
 		return "", fmt.Errorf("unable to parse output of svn info")
 	}
 	out = out[:i]
-	return strings.TrimSpace(string(out)), nil
+	return strings.TrimSpace(out), nil
 }
 
 func (v *vcsCmd) String() string {
@@ -383,9 +383,6 @@ func (v *vcsCmd) ping(scheme, repo string) error {
 // The parent of dir must exist; dir must not.
 func (v *vcsCmd) create(dir, repo string) error {
 	for _, cmd := range v.createCmd {
-		if !go15VendorExperiment && strings.Contains(cmd, "submodule") {
-			continue
-		}
 		if err := v.run(".", cmd, "dir", dir, "repo", repo); err != nil {
 			return err
 		}
@@ -396,9 +393,6 @@ func (v *vcsCmd) create(dir, repo string) error {
 // download downloads any new changes for the repo in dir.
 func (v *vcsCmd) download(dir string) error {
 	for _, cmd := range v.downloadCmd {
-		if !go15VendorExperiment && strings.Contains(cmd, "submodule") {
-			continue
-		}
 		if err := v.run(dir, cmd); err != nil {
 			return err
 		}
@@ -445,9 +439,6 @@ func (v *vcsCmd) tagSync(dir, tag string) error {
 
 	if tag == "" && v.tagSyncDefault != nil {
 		for _, cmd := range v.tagSyncDefault {
-			if !go15VendorExperiment && strings.Contains(cmd, "submodule") {
-				continue
-			}
 			if err := v.run(dir, cmd); err != nil {
 				return err
 			}
@@ -456,9 +447,6 @@ func (v *vcsCmd) tagSync(dir, tag string) error {
 	}
 
 	for _, cmd := range v.tagSyncCmd {
-		if !go15VendorExperiment && strings.Contains(cmd, "submodule") {
-			continue
-		}
 		if err := v.run(dir, cmd, "tag", tag); err != nil {
 			return err
 		}
@@ -479,15 +467,14 @@ type vcsPath struct {
 	regexp *regexp.Regexp // cached compiled form of re
 }
 
-// vcsForDir inspects dir and its parents to determine the
+// vcsFromDir inspects dir and its parents to determine the
 // version control system and code repository to use.
 // On return, root is the import path
-// corresponding to the root of the repository
-// (thus root is a prefix of importPath).
-func vcsForDir(p *Package) (vcs *vcsCmd, root string, err error) {
+// corresponding to the root of the repository.
+func vcsFromDir(dir, srcRoot string) (vcs *vcsCmd, root string, err error) {
 	// Clean and double-check that dir is in (a subdirectory of) srcRoot.
-	dir := filepath.Clean(p.Dir)
-	srcRoot := filepath.Clean(p.build.SrcRoot)
+	dir = filepath.Clean(dir)
+	srcRoot = filepath.Clean(srcRoot)
 	if len(dir) <= len(srcRoot) || dir[len(srcRoot)] != filepath.Separator {
 		return nil, "", fmt.Errorf("directory %q is outside source root %q", dir, srcRoot)
 	}
@@ -496,7 +483,7 @@ func vcsForDir(p *Package) (vcs *vcsCmd, root string, err error) {
 	for len(dir) > len(srcRoot) {
 		for _, vcs := range vcsList {
 			if fi, err := os.Stat(filepath.Join(dir, "."+vcs.cmd)); err == nil && fi.IsDir() {
-				return vcs, dir[len(srcRoot)+1:], nil
+				return vcs, filepath.ToSlash(dir[len(srcRoot)+1:]), nil
 			}
 		}
 
@@ -780,15 +767,31 @@ type metaImport struct {
 // errNoMatch is returned from matchGoImport when there's no applicable match.
 var errNoMatch = errors.New("no import match")
 
+func splitPathHasPrefix(path, prefix []string) bool {
+	if len(path) < len(prefix) {
+		return false
+	}
+	for i, p := range prefix {
+		if path[i] != p {
+			return false
+		}
+	}
+	return true
+}
+
 // matchGoImport returns the metaImport from imports matching importPath.
 // An error is returned if there are multiple matches.
 // errNoMatch is returned if none match.
 func matchGoImport(imports []metaImport, importPath string) (_ metaImport, err error) {
 	match := -1
+	imp := strings.Split(importPath, "/")
 	for i, im := range imports {
-		if !strings.HasPrefix(importPath, im.Prefix) {
+		pre := strings.Split(im.Prefix, "/")
+
+		if !splitPathHasPrefix(imp, pre) {
 			continue
 		}
+
 		if match != -1 {
 			err = fmt.Errorf("multiple meta tags match import path %q", importPath)
 			return
@@ -815,20 +818,6 @@ func expand(match map[string]string, s string) string {
 // and import paths referring to a fully-qualified importPath
 // containing a VCS type (foo.com/repo.git/dir)
 var vcsPaths = []*vcsPath{
-	// Google Code - new syntax
-	{
-		prefix: "code.google.com/",
-		re:     `^(?P<root>code\.google\.com/p/(?P<project>[a-z0-9\-]+)(\.(?P<subrepo>[a-z0-9\-]+))?)(/[A-Za-z0-9_.\-]+)*$`,
-		repo:   "https://{root}",
-		check:  googleCodeVCS,
-	},
-
-	// Google Code - old syntax
-	{
-		re:    `^(?P<project>[a-z0-9_\-.]+)\.googlecode\.com/(git|hg|svn)(?P<path>/.*)?$`,
-		check: oldGoogleCode,
-	},
-
 	// Github
 	{
 		prefix: "github.com/",
@@ -863,6 +852,14 @@ var vcsPaths = []*vcsPath{
 		repo:   "https://{root}",
 	},
 
+	// Git at OpenStack
+	{
+		prefix: "git.openstack.org",
+		re:     `^(?P<root>git\.openstack\.org/[A-Za-z0-9_.\-]+/[A-Za-z0-9_.\-]+)(\.git)?(/[A-Za-z0-9_.\-]+)*$`,
+		vcs:    "git",
+		repo:   "https://{root}",
+	},
+
 	// General syntax for any server.
 	// Must be last.
 	{
@@ -911,45 +908,6 @@ func noVCSSuffix(match map[string]string) error {
 	return nil
 }
 
-var googleCheckout = regexp.MustCompile(`id="checkoutcmd">(hg|git|svn)`)
-
-// googleCodeVCS determines the version control system for
-// a code.google.com repository, by scraping the project's
-// /source/checkout page.
-func googleCodeVCS(match map[string]string) error {
-	if err := noVCSSuffix(match); err != nil {
-		return err
-	}
-	data, err := httpGET(expand(match, "https://code.google.com/p/{project}/source/checkout?repo={subrepo}"))
-	if err != nil {
-		return err
-	}
-
-	if m := googleCheckout.FindSubmatch(data); m != nil {
-		if vcs := vcsByCmd(string(m[1])); vcs != nil {
-			// Subversion requires the old URLs.
-			// TODO: Test.
-			if vcs == vcsSvn {
-				if match["subrepo"] != "" {
-					return fmt.Errorf("sub-repositories not supported in Google Code Subversion projects")
-				}
-				match["repo"] = expand(match, "https://{project}.googlecode.com/svn")
-			}
-			match["vcs"] = vcs.cmd
-			return nil
-		}
-	}
-
-	return fmt.Errorf("unable to detect version control system for code.google.com/ path")
-}
-
-// oldGoogleCode is invoked for old-style foo.googlecode.com paths.
-// It prints an error giving the equivalent new path.
-func oldGoogleCode(match map[string]string) error {
-	return fmt.Errorf("invalid Google Code import path: use %s instead",
-		expand(match, "code.google.com/p/{project}{path}"))
-}
-
 // bitbucketVCS determines the version control system for a
 // Bitbucket repository, by using the Bitbucket API.
 func bitbucketVCS(match map[string]string) error {
diff --git a/libgo/go/cmd/go/vcs_test.go b/libgo/go/cmd/go/vcs_test.go
index a90c2061edb..25e3866df06 100644
--- a/libgo/go/cmd/go/vcs_test.go
+++ b/libgo/go/cmd/go/vcs_test.go
@@ -1,11 +1,16 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package main
 
 import (
+	"errors"
 	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"path"
+	"path/filepath"
 	"testing"
 )
 
@@ -18,20 +23,6 @@ func TestRepoRootForImportPath(t *testing.T) {
 		path string
 		want *repoRoot
 	}{
-		/*{
-			"code.google.com/p/go",
-			&repoRoot{
-				vcs:  vcsHg,
-				repo: "https://code.google.com/p/go",
-			},
-		},
-		{
-		        "code.google.com/r/go",
-		        &repoRoot{
-		                vcs:  vcsHg,
-		                repo: "https://code.google.com/r/go",
-		        },
-		},*/
 		{
 			"github.com/golang/groupcache",
 			&repoRoot{
@@ -96,6 +87,39 @@ func TestRepoRootForImportPath(t *testing.T) {
 			"hub.jazz.net/git/USER/pkgname",
 			nil,
 		},
+		// OpenStack tests
+		{
+			"git.openstack.org/openstack/swift",
+			&repoRoot{
+				vcs:  vcsGit,
+				repo: "https://git.openstack.org/openstack/swift",
+			},
+		},
+		// Trailing .git is less preferred but included for
+		// compatibility purposes while the same source needs to
+		// be compilable on both old and new go
+		{
+			"git.openstack.org/openstack/swift.git",
+			&repoRoot{
+				vcs:  vcsGit,
+				repo: "https://git.openstack.org/openstack/swift",
+			},
+		},
+		{
+			"git.openstack.org/openstack/swift/go/hummingbird",
+			&repoRoot{
+				vcs:  vcsGit,
+				repo: "https://git.openstack.org/openstack/swift",
+			},
+		},
+		{
+			"git.openstack.org",
+			nil,
+		},
+		{
+			"git.openstack.org/openstack",
+			nil,
+		},
 		// Spaces are not valid in package name
 		{
 			"git.apache.org/package name/path/to/lib",
@@ -142,6 +166,37 @@ func TestRepoRootForImportPath(t *testing.T) {
 	}
 }
 
+// Test that vcsFromDir correctly inspects a given directory and returns the right VCS and root.
+func TestFromDir(t *testing.T) {
+	tempDir, err := ioutil.TempDir("", "vcstest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	for _, vcs := range vcsList {
+		dir := filepath.Join(tempDir, "example.com", vcs.name, "."+vcs.cmd)
+		err := os.MkdirAll(dir, 0755)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		want := repoRoot{
+			vcs:  vcs,
+			root: path.Join("example.com", vcs.name),
+		}
+		var got repoRoot
+		got.vcs, got.root, err = vcsFromDir(dir, tempDir)
+		if err != nil {
+			t.Errorf("FromDir(%q, %q): %v", dir, tempDir, err)
+			continue
+		}
+		if got.vcs.name != want.vcs.name || got.root != want.root {
+			t.Errorf("FromDir(%q, %q) = VCS(%s) Root(%s), want VCS(%s) Root(%s)", dir, tempDir, got.vcs, got.root, want.vcs, want.root)
+		}
+	}
+}
+
 func TestIsSecure(t *testing.T) {
 	tests := []struct {
 		vcs    *vcsCmd
@@ -173,3 +228,96 @@ func TestIsSecure(t *testing.T) {
 		}
 	}
 }
+
+func TestMatchGoImport(t *testing.T) {
+	tests := []struct {
+		imports []metaImport
+		path    string
+		mi      metaImport
+		err     error
+	}{
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo",
+			mi:   metaImport{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo/",
+			mi:   metaImport{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/fooa", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo",
+			mi:   metaImport{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/fooa", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/fooa",
+			mi:   metaImport{Prefix: "example.com/user/fooa", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/foo/bar", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo/bar",
+			err:  errors.New("should not be allowed to create nested repo"),
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/foo/bar", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo/bar/baz",
+			err:  errors.New("should not be allowed to create nested repo"),
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/foo/bar", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo/bar/baz/qux",
+			err:  errors.New("should not be allowed to create nested repo"),
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/foo/bar", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com/user/foo/bar/baz/",
+			err:  errors.New("should not be allowed to create nested repo"),
+		},
+		{
+			imports: []metaImport{
+				{Prefix: "example.com/user/foo", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+				{Prefix: "example.com/user/foo/bar", VCS: "git", RepoRoot: "https://example.com/repo/target"},
+			},
+			path: "example.com",
+			err:  errors.New("pathologically short path"),
+		},
+	}
+
+	for _, test := range tests {
+		mi, err := matchGoImport(test.imports, test.path)
+		if mi != test.mi {
+			t.Errorf("unexpected metaImport; got %v, want %v", mi, test.mi)
+		}
+
+		got := err
+		want := test.err
+		if (got == nil) != (want == nil) {
+			t.Errorf("unexpected error; got %v, want %v", got, want)
+		}
+	}
+}
diff --git a/libgo/go/cmd/go/vendor_test.go b/libgo/go/cmd/go/vendor_test.go
index 006a8c9d3f4..226b5377b98 100644
--- a/libgo/go/cmd/go/vendor_test.go
+++ b/libgo/go/cmd/go/vendor_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -20,7 +20,6 @@ func TestVendorImports(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.run("list", "-f", "{{.ImportPath}} {{.Imports}}", "vend/...")
 	want := `
 		vend [vend/vendor/p r]
@@ -51,7 +50,6 @@ func TestVendorBuild(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.run("build", "vend/x")
 }
 
@@ -59,7 +57,6 @@ func TestVendorRun(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.cd(filepath.Join(tg.pwd(), "testdata/src/vend/hello"))
 	tg.run("run", "hello.go")
 	tg.grepStdout("hello, world", "missing hello world output")
@@ -74,7 +71,6 @@ func TestVendorGOPATH(t *testing.T) {
 	}
 	gopath := changeVolume(filepath.Join(tg.pwd(), "testdata"), strings.ToLower)
 	tg.setenv("GOPATH", gopath)
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	cd := changeVolume(filepath.Join(tg.pwd(), "testdata/src/vend/hello"), strings.ToUpper)
 	tg.cd(cd)
 	tg.run("run", "hello.go")
@@ -85,7 +81,6 @@ func TestVendorTest(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.cd(filepath.Join(tg.pwd(), "testdata/src/vend/hello"))
 	tg.run("test", "-v")
 	tg.grepStdout("TestMsgInternal", "missing use in internal test")
@@ -96,7 +91,6 @@ func TestVendorInvalid(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 
 	tg.runFail("build", "vend/x/invalid")
 	tg.grepStderr("must be imported as foo", "missing vendor import error")
@@ -106,7 +100,6 @@ func TestVendorImportError(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 
 	tg.runFail("build", "vend/x/vendor/p/p")
 
@@ -173,7 +166,6 @@ func TestVendorGet(t *testing.T) {
 		package p
 		const C = 1`)
 	tg.setenv("GOPATH", tg.path("."))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.cd(tg.path("src/v"))
 	tg.run("run", "m.go")
 	tg.run("test")
@@ -192,7 +184,6 @@ func TestVendorGetUpdate(t *testing.T) {
 	defer tg.cleanup()
 	tg.makeTempdir()
 	tg.setenv("GOPATH", tg.path("."))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.run("get", "github.com/rsc/go-get-issue-11864")
 	tg.run("get", "-u", "github.com/rsc/go-get-issue-11864")
 }
@@ -204,16 +195,15 @@ func TestGetSubmodules(t *testing.T) {
 	defer tg.cleanup()
 	tg.makeTempdir()
 	tg.setenv("GOPATH", tg.path("."))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.run("get", "-d", "github.com/rsc/go-get-issue-12612")
 	tg.run("get", "-u", "-d", "github.com/rsc/go-get-issue-12612")
+	tg.mustExist(tg.path("src/github.com/rsc/go-get-issue-12612/vendor/golang.org/x/crypto/.git"))
 }
 
 func TestVendorCache(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata/testvendor"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.runFail("build", "p")
 	tg.grepStderr("must be imported as x", "did not fail to build p")
 }
@@ -225,7 +215,6 @@ func TestVendorTest2(t *testing.T) {
 	defer tg.cleanup()
 	tg.makeTempdir()
 	tg.setenv("GOPATH", tg.path("."))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.run("get", "github.com/rsc/go-get-issue-11864")
 
 	// build -i should work
@@ -244,6 +233,32 @@ func TestVendorTest2(t *testing.T) {
 	tg.run("test", "github.com/rsc/go-get-issue-11864/vendor/vendor.org/tx2")
 }
 
+func TestVendorTest3(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.makeTempdir()
+	tg.setenv("GOPATH", tg.path("."))
+	tg.run("get", "github.com/clsung/go-vendor-issue-14613")
+
+	tg.run("build", "-o", tg.path("a.out"), "-i", "github.com/clsung/go-vendor-issue-14613")
+
+	// test folder should work
+	tg.run("test", "-i", "github.com/clsung/go-vendor-issue-14613")
+	tg.run("test", "github.com/clsung/go-vendor-issue-14613")
+
+	// test with specified _test.go should work too
+	tg.cd(filepath.Join(tg.path("."), "src"))
+	tg.run("test", "-i", "github.com/clsung/go-vendor-issue-14613/vendor_test.go")
+	tg.run("test", "github.com/clsung/go-vendor-issue-14613/vendor_test.go")
+
+	// test with imported and not used
+	tg.run("test", "-i", "github.com/clsung/go-vendor-issue-14613/vendor/mylibtesttest/myapp/myapp_test.go")
+	tg.runFail("test", "github.com/clsung/go-vendor-issue-14613/vendor/mylibtesttest/myapp/myapp_test.go")
+	tg.grepStderr("imported and not used:", `should say "imported and not used"`)
+}
+
 func TestVendorList(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 
@@ -251,7 +266,6 @@ func TestVendorList(t *testing.T) {
 	defer tg.cleanup()
 	tg.makeTempdir()
 	tg.setenv("GOPATH", tg.path("."))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.run("get", "github.com/rsc/go-get-issue-11864")
 
 	tg.run("list", "-f", `{{join .TestImports "\n"}}`, "github.com/rsc/go-get-issue-11864/t")
@@ -272,7 +286,6 @@ func TestVendor12156(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata/testvendor2"))
-	tg.setenv("GO15VENDOREXPERIMENT", "1")
 	tg.cd(filepath.Join(tg.pwd(), "testdata/testvendor2/src/p"))
 	tg.runFail("build", "p.go")
 	tg.grepStderrNot("panic", "panicked")
diff --git a/libgo/go/cmd/go/version.go b/libgo/go/cmd/go/version.go
index a41f4a73615..3045f350d7d 100644
--- a/libgo/go/cmd/go/version.go
+++ b/libgo/go/cmd/go/version.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/go/vet.go b/libgo/go/cmd/go/vet.go
index 81b978e8dab..8e296c8572e 100644
--- a/libgo/go/cmd/go/vet.go
+++ b/libgo/go/cmd/go/vet.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/cmd/gofmt/gofmt.go b/libgo/go/cmd/gofmt/gofmt.go
index cfebeffe4a6..f29b6cb83d9 100644
--- a/libgo/go/cmd/gofmt/gofmt.go
+++ b/libgo/go/cmd/gofmt/gofmt.go
@@ -55,7 +55,6 @@ func report(err error) {
 func usage() {
 	fmt.Fprintf(os.Stderr, "usage: gofmt [flags] [path ...]\n")
 	flag.PrintDefaults()
-	os.Exit(2)
 }
 
 func initParserMode() {
@@ -143,7 +142,9 @@ func visitFile(path string, f os.FileInfo, err error) error {
 	if err == nil && isGoFile(f) {
 		err = processFile(path, nil, os.Stdout, false)
 	}
-	if err != nil {
+	// Don't complain if a file was deleted in the meantime (i.e.
+	// the directory changed concurrently while running gofmt).
+	if err != nil && !os.IsNotExist(err) {
 		report(err)
 	}
 	return nil
diff --git a/libgo/go/cmd/gofmt/gofmt_test.go b/libgo/go/cmd/gofmt/gofmt_test.go
index d1edb7bcc16..dea012764b3 100644
--- a/libgo/go/cmd/gofmt/gofmt_test.go
+++ b/libgo/go/cmd/gofmt/gofmt_test.go
@@ -159,7 +159,7 @@ func TestCRLF(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	if bytes.Index(data, []byte("\r\n")) < 0 {
+	if !bytes.Contains(data, []byte("\r\n")) {
 		t.Errorf("%s contains no CR/LF's", input)
 	}
 
@@ -167,7 +167,7 @@ func TestCRLF(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	if bytes.Index(data, []byte("\r")) >= 0 {
+	if bytes.Contains(data, []byte("\r")) {
 		t.Errorf("%s contains CR's", golden)
 	}
 }
diff --git a/libgo/go/cmd/gofmt/internal.go b/libgo/go/cmd/gofmt/internal.go
index f764b10ebb0..cbc6983b612 100644
--- a/libgo/go/cmd/gofmt/internal.go
+++ b/libgo/go/cmd/gofmt/internal.go
@@ -28,9 +28,9 @@ func parse(fset *token.FileSet, filename string, src []byte, fragmentOk bool) (
 ) {
 	// Try as whole source file.
 	file, err = parser.ParseFile(fset, filename, src, parserMode)
-	// If there's no error, return.  If the error is that the source file didn't begin with a
+	// If there's no error, return. If the error is that the source file didn't begin with a
 	// package line and source fragments are ok, fall through to
-	// try as a source fragment.  Stop and return on any other error.
+	// try as a source fragment. Stop and return on any other error.
 	if err == nil || !fragmentOk || !strings.Contains(err.Error(), "expected 'package'") {
 		return
 	}
@@ -59,7 +59,7 @@ func parse(fset *token.FileSet, filename string, src []byte, fragmentOk bool) (
 
 	// If this is a statement list, make it a source file
 	// by inserting a package clause and turning the list
-	// into a function body.  This handles expressions too.
+	// into a function body. This handles expressions too.
 	// Insert using a ;, not a newline, so that the line numbers
 	// in fsrc match the ones in src. Add an extra '\n' before the '}'
 	// to make sure comments are flushed before the '}'.
diff --git a/libgo/go/cmd/gofmt/rewrite.go b/libgo/go/cmd/gofmt/rewrite.go
index 069f96622ca..550492bf29a 100644
--- a/libgo/go/cmd/gofmt/rewrite.go
+++ b/libgo/go/cmd/gofmt/rewrite.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -158,7 +158,7 @@ func isWildcard(s string) bool {
 // recording wildcard submatches in m.
 // If m == nil, match checks whether pattern == val.
 func match(m map[string]reflect.Value, pattern, val reflect.Value) bool {
-	// Wildcard matches any expression.  If it appears multiple
+	// Wildcard matches any expression. If it appears multiple
 	// times in the pattern, it must match the same expression
 	// each time.
 	if m != nil && pattern.IsValid() && pattern.Type() == identType {
diff --git a/libgo/go/cmd/gofmt/simplify.go b/libgo/go/cmd/gofmt/simplify.go
index 69f7bf23c0b..2ebf4cde0be 100644
--- a/libgo/go/cmd/gofmt/simplify.go
+++ b/libgo/go/cmd/gofmt/simplify.go
@@ -10,11 +10,9 @@ import (
 	"reflect"
 )
 
-type simplifier struct {
-	hasDotImport bool // package file contains: import . "some/import/path"
-}
+type simplifier struct{}
 
-func (s *simplifier) Visit(node ast.Node) ast.Visitor {
+func (s simplifier) Visit(node ast.Node) ast.Visitor {
 	switch n := node.(type) {
 	case *ast.CompositeLit:
 		// array, slice, and map composite literals may be simplified
@@ -68,10 +66,13 @@ func (s *simplifier) Visit(node ast.Node) ast.Visitor {
 		// a slice expression of the form: s[a:len(s)]
 		// can be simplified to: s[a:]
 		// if s is "simple enough" (for now we only accept identifiers)
-		if n.Max != nil || s.hasDotImport {
+		//
+		// Note: This may not be correct because len may have been redeclared in another
+		//       file belonging to the same package. However, this is extremely unlikely
+		//       and so far (April 2016, after years of supporting this rewrite feature)
+		//       has never come up, so let's keep it working as is (see also #15153).
+		if n.Max != nil {
 			// - 3-index slices always require the 2nd and 3rd index
-			// - if dot imports are present, we cannot be certain that an
-			//   unresolved "len" identifier refers to the predefined len()
 			break
 		}
 		if s, _ := n.X.(*ast.Ident); s != nil && s.Obj != nil {
@@ -118,20 +119,11 @@ func isBlank(x ast.Expr) bool {
 }
 
 func simplify(f *ast.File) {
-	var s simplifier
-
-	// determine if f contains dot imports
-	for _, imp := range f.Imports {
-		if imp.Name != nil && imp.Name.Name == "." {
-			s.hasDotImport = true
-			break
-		}
-	}
-
 	// remove empty declarations such as "const ()", etc
 	removeEmptyDeclGroups(f)
 
-	ast.Walk(&s, f)
+	var s simplifier
+	ast.Walk(s, f)
 }
 
 func removeEmptyDeclGroups(f *ast.File) {
diff --git a/libgo/go/cmd/gofmt/testdata/slices2.golden b/libgo/go/cmd/gofmt/testdata/slices2.golden
deleted file mode 100644
index ab657004e64..00000000000
--- a/libgo/go/cmd/gofmt/testdata/slices2.golden
+++ /dev/null
@@ -1,63 +0,0 @@
-//gofmt -s
-
-// Test cases for slice expression simplification.
-// Because of a dot import, these slices must remain untouched.
-package p
-
-import . "math"
-
-var (
-	a [10]byte
-	b [20]float32
-	s []int
-	t struct {
-		s []byte
-	}
-
-	_ = a[0:]
-	_ = a[1:10]
-	_ = a[2:len(a)]
-	_ = a[3:(len(a))]
-	_ = a[len(a) : len(a)-1]
-	_ = a[0:len(b)]
-
-	_ = a[:]
-	_ = a[:10]
-	_ = a[:len(a)]
-	_ = a[:(len(a))]
-	_ = a[:len(a)-1]
-	_ = a[:len(b)]
-
-	_ = s[0:]
-	_ = s[1:10]
-	_ = s[2:len(s)]
-	_ = s[3:(len(s))]
-	_ = s[len(a) : len(s)-1]
-	_ = s[0:len(b)]
-
-	_ = s[:]
-	_ = s[:10]
-	_ = s[:len(s)]
-	_ = s[:(len(s))]
-	_ = s[:len(s)-1]
-	_ = s[:len(b)]
-
-	_ = t.s[0:]
-	_ = t.s[1:10]
-	_ = t.s[2:len(t.s)]
-	_ = t.s[3:(len(t.s))]
-	_ = t.s[len(a) : len(t.s)-1]
-	_ = t.s[0:len(b)]
-
-	_ = t.s[:]
-	_ = t.s[:10]
-	_ = t.s[:len(t.s)]
-	_ = t.s[:(len(t.s))]
-	_ = t.s[:len(t.s)-1]
-	_ = t.s[:len(b)]
-)
-
-func _() {
-	s := s[0:len(s)]
-	_ = s
-}
diff --git a/libgo/go/cmd/gofmt/testdata/slices2.input b/libgo/go/cmd/gofmt/testdata/slices2.input
deleted file mode 100644
index ab657004e64..00000000000
--- a/libgo/go/cmd/gofmt/testdata/slices2.input
+++ /dev/null
@@ -1,63 +0,0 @@
-//gofmt -s
-
-// Test cases for slice expression simplification.
-// Because of a dot import, these slices must remain untouched.
-package p
-
-import . "math"
-
-var (
-	a [10]byte
-	b [20]float32
-	s []int
-	t struct {
-		s []byte
-	}
-
-	_ = a[0:]
-	_ = a[1:10]
-	_ = a[2:len(a)]
-	_ = a[3:(len(a))]
-	_ = a[len(a) : len(a)-1]
-	_ = a[0:len(b)]
-
-	_ = a[:]
-	_ = a[:10]
-	_ = a[:len(a)]
-	_ = a[:(len(a))]
-	_ = a[:len(a)-1]
-	_ = a[:len(b)]
-
-	_ = s[0:]
-	_ = s[1:10]
-	_ = s[2:len(s)]
-	_ = s[3:(len(s))]
-	_ = s[len(a) : len(s)-1]
-	_ = s[0:len(b)]
-
-	_ = s[:]
-	_ = s[:10]
-	_ = s[:len(s)]
-	_ = s[:(len(s))]
-	_ = s[:len(s)-1]
-	_ = s[:len(b)]
-
-	_ = t.s[0:]
-	_ = t.s[1:10]
-	_ = t.s[2:len(t.s)]
-	_ = t.s[3:(len(t.s))]
-	_ = t.s[len(a) : len(t.s)-1]
-	_ = t.s[0:len(b)]
-
-	_ = t.s[:]
-	_ = t.s[:10]
-	_ = t.s[:len(t.s)]
-	_ = t.s[:(len(t.s))]
-	_ = t.s[:len(t.s)-1]
-	_ = t.s[:len(b)]
-)
-
-func _() {
-	s := s[0:len(s)]
-	_ = s
-}
diff --git a/libgo/go/compress/bzip2/bzip2.go b/libgo/go/compress/bzip2/bzip2.go
index 68979572708..42788443bcf 100644
--- a/libgo/go/compress/bzip2/bzip2.go
+++ b/libgo/go/compress/bzip2/bzip2.go
@@ -27,9 +27,8 @@ type reader struct {
 	blockCRC     uint32
 	wantBlockCRC uint32
 	setupDone    bool // true if we have parsed the bzip2 header.
-	blockSize    int  // blockSize in bytes, i.e. 900 * 1024.
+	blockSize    int  // blockSize in bytes, i.e. 900 * 1000.
 	eof          bool
-	buf          []byte    // stores Burrows-Wheeler transformed data.
 	c            [256]uint // the `C' array for the inverse BWT.
 	tt           []uint32  // mirrors the `tt' array in the bzip2 source and contains the P array in the upper 24 bits.
 	tPos         uint32    // Index of the next output byte in tt.
@@ -76,7 +75,7 @@ func (bz2 *reader) setup(needMagic bool) error {
 	}
 
 	bz2.fileCRC = 0
-	bz2.blockSize = 100 * 1024 * (int(level) - '0')
+	bz2.blockSize = 100 * 1000 * (level - '0')
 	if bz2.blockSize > len(bz2.tt) {
 		bz2.tt = make([]uint32, bz2.blockSize)
 	}
@@ -294,7 +293,7 @@ func (bz2 *reader) readBlock() (err error) {
 		if c >= numHuffmanTrees {
 			return StructuralError("tree index too large")
 		}
-		treeIndexes[i] = uint8(mtfTreeDecoder.Decode(c))
+		treeIndexes[i] = mtfTreeDecoder.Decode(c)
 	}
 
 	// The list of symbols for the move-to-front transform is taken from
@@ -319,6 +318,9 @@ func (bz2 *reader) readBlock() (err error) {
 		length := br.ReadBits(5)
 		for j := range lengths {
 			for {
+				if length < 1 || length > 20 {
+					return StructuralError("Huffman length out of range")
+				}
 				if !br.ReadBit() {
 					break
 				}
@@ -328,9 +330,6 @@ func (bz2 *reader) readBlock() (err error) {
 					length++
 				}
 			}
-			if length < 0 || length > 20 {
-				return StructuralError("Huffman length out of range")
-			}
 			lengths[j] = uint8(length)
 		}
 		huffmanTrees[i], err = newHuffmanTree(lengths)
@@ -400,7 +399,7 @@ func (bz2 *reader) readBlock() (err error) {
 				return StructuralError("repeats past end of block")
 			}
 			for i := 0; i < repeat; i++ {
-				b := byte(mtf.First())
+				b := mtf.First()
 				bz2.tt[bufIndex] = uint32(b)
 				bz2.c[b]++
 				bufIndex++
@@ -421,7 +420,7 @@ func (bz2 *reader) readBlock() (err error) {
 		// it's always referenced with a run-length of 1. Thus 0
 		// doesn't need to be encoded and we have |v-1| in the next
 		// line.
-		b := byte(mtf.Decode(int(v - 1)))
+		b := mtf.Decode(int(v - 1))
 		if bufIndex >= bz2.blockSize {
 			return StructuralError("data exceeds block size")
 		}
diff --git a/libgo/go/compress/bzip2/bzip2_test.go b/libgo/go/compress/bzip2/bzip2_test.go
index 7293d4e3bef..a6c3080db3e 100644
--- a/libgo/go/compress/bzip2/bzip2_test.go
+++ b/libgo/go/compress/bzip2/bzip2_test.go
@@ -6,193 +6,221 @@ package bzip2
 
 import (
 	"bytes"
-	"encoding/base64"
 	"encoding/hex"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"testing"
 )
 
-func TestBitReader(t *testing.T) {
-	buf := bytes.NewReader([]byte{0xaa})
-	br := newBitReader(buf)
-	if n := br.ReadBits(1); n != 1 {
-		t.Errorf("read 1 wrong")
-	}
-	if n := br.ReadBits(1); n != 0 {
-		t.Errorf("read 2 wrong")
-	}
-	if n := br.ReadBits(1); n != 1 {
-		t.Errorf("read 3 wrong")
-	}
-	if n := br.ReadBits(1); n != 0 {
-		t.Errorf("read 4 wrong")
-	}
-}
-
-func TestBitReaderLarge(t *testing.T) {
-	buf := bytes.NewReader([]byte{0x12, 0x34, 0x56, 0x78})
-	br := newBitReader(buf)
-	if n := br.ReadBits(32); n != 0x12345678 {
-		t.Errorf("got: %x want: %x", n, 0x12345678)
-	}
-}
-
-func readerFromHex(s string) io.Reader {
-	data, err := hex.DecodeString(s)
-	if err != nil {
-		panic("readerFromHex: bad input")
-	}
-	return bytes.NewReader(data)
-}
-
-func decompressHex(s string) (out []byte, err error) {
-	r := NewReader(readerFromHex(s))
-	return ioutil.ReadAll(r)
-}
-
-func TestHelloWorldBZ2(t *testing.T) {
-	out, err := decompressHex(helloWorldBZ2Hex)
+func mustDecodeHex(s string) []byte {
+	b, err := hex.DecodeString(s)
 	if err != nil {
-		t.Errorf("error from Read: %s", err)
-		return
-	}
-
-	if !bytes.Equal(helloWorld, out) {
-		t.Errorf("got %x, want %x", out, helloWorld)
+		panic(err)
 	}
+	return b
 }
 
-func TestConcat(t *testing.T) {
-	out, err := decompressHex(helloWorldBZ2Hex + helloWorldBZ2Hex)
+func mustLoadFile(f string) []byte {
+	b, err := ioutil.ReadFile(f)
 	if err != nil {
-		t.Errorf("error from Read: %s", err)
-		return
-	}
-
-	hello2 := bytes.Repeat(helloWorld, 2)
-	if !bytes.Equal(hello2, out) {
-		t.Errorf("got %x, want %x", out, hello2)
-	}
-}
-
-func testZeros(t *testing.T, inHex string, n int) {
-	out, err := decompressHex(inHex)
-	if err != nil {
-		t.Errorf("error from Read: %s", err)
-		return
-	}
-
-	expected := make([]byte, n)
-
-	if !bytes.Equal(expected, out) {
-		allZeros := true
-		for _, b := range out {
-			if b != 0 {
-				allZeros = false
-				break
+		panic(err)
+	}
+	return b
+}
+
+func trim(b []byte) string {
+	const limit = 1024
+	if len(b) < limit {
+		return fmt.Sprintf("%q", b)
+	}
+	return fmt.Sprintf("%q...", b[:limit])
+}
+
+func TestReader(t *testing.T) {
+	var vectors = []struct {
+		desc   string
+		input  []byte
+		output []byte
+		fail   bool
+	}{{
+		desc: "hello world",
+		input: mustDecodeHex("" +
+			"425a68393141592653594eece83600000251800010400006449080200031064c" +
+			"4101a7a9a580bb9431f8bb9229c28482776741b0",
+		),
+		output: []byte("hello world\n"),
+	}, {
+		desc: "concatenated files",
+		input: mustDecodeHex("" +
+			"425a68393141592653594eece83600000251800010400006449080200031064c" +
+			"4101a7a9a580bb9431f8bb9229c28482776741b0425a68393141592653594eec" +
+			"e83600000251800010400006449080200031064c4101a7a9a580bb9431f8bb92" +
+			"29c28482776741b0",
+		),
+		output: []byte("hello world\nhello world\n"),
+	}, {
+		desc: "32B zeros",
+		input: mustDecodeHex("" +
+			"425a6839314159265359b5aa5098000000600040000004200021008283177245" +
+			"385090b5aa5098",
+		),
+		output: make([]byte, 32),
+	}, {
+		desc: "1MiB zeros",
+		input: mustDecodeHex("" +
+			"425a683931415926535938571ce50008084000c0040008200030cc0529a60806" +
+			"c4201e2ee48a70a12070ae39ca",
+		),
+		output: make([]byte, 1<<20),
+	}, {
+		desc:   "random data",
+		input:  mustLoadFile("testdata/pass-random1.bz2"),
+		output: mustLoadFile("testdata/pass-random1.bin"),
+	}, {
+		desc:   "random data - full symbol range",
+		input:  mustLoadFile("testdata/pass-random2.bz2"),
+		output: mustLoadFile("testdata/pass-random2.bin"),
+	}, {
+		desc: "random data - uses RLE1 stage",
+		input: mustDecodeHex("" +
+			"425a6839314159265359d992d0f60000137dfe84020310091c1e280e100e0428" +
+			"01099210094806c0110002e70806402000546034000034000000f28300000320" +
+			"00d3403264049270eb7a9280d308ca06ad28f6981bee1bf8160727c7364510d7" +
+			"3a1e123083421b63f031f63993a0f40051fbf177245385090d992d0f60",
+		),
+		output: mustDecodeHex("" +
+			"92d5652616ac444a4a04af1a8a3964aca0450d43d6cf233bd03233f4ba92f871" +
+			"9e6c2a2bd4f5f88db07ecd0da3a33b263483db9b2c158786ad6363be35d17335" +
+			"ba",
+		),
+	}, {
+		desc:  "1MiB sawtooth",
+		input: mustLoadFile("testdata/pass-sawtooth.bz2"),
+		output: func() []byte {
+			b := make([]byte, 1<<20)
+			for i := range b {
+				b[i] = byte(i)
+			}
+			return b
+		}(),
+	}, {
+		desc:  "RLE2 buffer overrun - issue 5747",
+		input: mustLoadFile("testdata/fail-issue5747.bz2"),
+		fail:  true,
+	}, {
+		desc: "out-of-range selector - issue 8363",
+		input: mustDecodeHex("" +
+			"425a68393141592653594eece83600000251800010400006449080200031064c" +
+			"4101a7a9a580bb943117724538509000000000",
+		),
+		fail: true,
+	}, {
+		desc: "bad block size - issue 13941",
+		input: mustDecodeHex("" +
+			"425a683131415926535936dc55330063ffc0006000200020a40830008b0008b8" +
+			"bb9229c28481b6e2a998",
+		),
+		fail: true,
+	}, {
+		desc: "bad huffman delta",
+		input: mustDecodeHex("" +
+			"425a6836314159265359b1f7404b000000400040002000217d184682ee48a70a" +
+			"12163ee80960",
+		),
+		fail: true,
+	}}
+
+	for i, v := range vectors {
+		rd := NewReader(bytes.NewReader(v.input))
+		buf, err := ioutil.ReadAll(rd)
+
+		if fail := bool(err != nil); fail != v.fail {
+			if fail {
+				t.Errorf("test %d (%s), unexpected failure: %v", i, v.desc, err)
+			} else {
+				t.Errorf("test %d (%s), unexpected success", i, v.desc)
 			}
 		}
-		t.Errorf("incorrect result, got %d bytes (allZeros: %t)", len(out), allZeros)
+		if !v.fail && !bytes.Equal(buf, v.output) {
+			t.Errorf("test %d (%s), output mismatch:\ngot  %s\nwant %s", i, v.desc, trim(buf), trim(v.output))
+		}
 	}
 }
 
-func Test32Zeros(t *testing.T) {
-	testZeros(t, thirtyTwoZerosBZ2Hex, 32)
-}
-
-func Test1MBZeros(t *testing.T) {
-	testZeros(t, oneMBZerosBZ2Hex, 1024*1024)
-}
-
-func testRandomData(t *testing.T, compressedHex, uncompressedHex string) {
-	out, err := decompressHex(compressedHex)
-	if err != nil {
-		t.Errorf("error from Read: %s", err)
-		return
-	}
-
-	expected, _ := hex.DecodeString(uncompressedHex)
-
-	if !bytes.Equal(out, expected) {
-		t.Errorf("incorrect result\ngot:  %x\nwant: %x", out, expected)
+func TestBitReader(t *testing.T) {
+	var vectors = []struct {
+		nbits uint // Number of bits to read
+		value int  // Expected output value (0 for error)
+		fail  bool // Expected operation failure?
+	}{
+		{nbits: 1, value: 1},
+		{nbits: 1, value: 0},
+		{nbits: 1, value: 1},
+		{nbits: 5, value: 11},
+		{nbits: 32, value: 0x12345678},
+		{nbits: 15, value: 14495},
+		{nbits: 3, value: 6},
+		{nbits: 6, value: 13},
+		{nbits: 1, fail: true},
+	}
+
+	rd := bytes.NewReader([]byte{0xab, 0x12, 0x34, 0x56, 0x78, 0x71, 0x3f, 0x8d})
+	br := newBitReader(rd)
+	for i, v := range vectors {
+		val := br.ReadBits(v.nbits)
+		if fail := bool(br.err != nil); fail != v.fail {
+			if fail {
+				t.Errorf("test %d, unexpected failure: ReadBits(%d) = %v", i, v.nbits, br.err)
+			} else {
+				t.Errorf("test %d, unexpected success: ReadBits(%d) = nil", i, v.nbits)
+			}
+		}
+		if !v.fail && val != v.value {
+			t.Errorf("test %d, mismatching value: ReadBits(%d) = %d, want %d", i, v.nbits, val, v.value)
+		}
 	}
 }
 
-func TestRandomData1(t *testing.T) {
-	testRandomData(t, randBZ2Hex, randHex)
-}
-
-func TestRandomData2(t *testing.T) {
-	// This test involves several repeated bytes in the output, but they
-	// should trigger RLE decoding.
-	testRandomData(t, rand2BZ2Hex, rand2Hex)
-}
-
-func TestRandomData3(t *testing.T) {
-	// This test uses the full range of symbols.
-	testRandomData(t, rand3BZ2Hex, rand3Hex)
-}
-
-func Test1MBSawtooth(t *testing.T) {
-	out, err := decompressHex(oneMBSawtoothBZ2Hex)
-	if err != nil {
-		t.Errorf("error from Read: %s", err)
-		return
-	}
-
-	expected := make([]byte, 1024*1024)
-
-	for i := range expected {
-		expected[i] = byte(i)
+func TestMTF(t *testing.T) {
+	var vectors = []struct {
+		idx int   // Input index
+		sym uint8 // Expected output symbol
+	}{
+		{idx: 1, sym: 1}, // [1 0 2 3 4]
+		{idx: 0, sym: 1}, // [1 0 2 3 4]
+		{idx: 1, sym: 0}, // [0 1 2 3 4]
+		{idx: 4, sym: 4}, // [4 0 1 2 3]
+		{idx: 1, sym: 0}, // [0 4 1 2 3]
 	}
 
-	if !bytes.Equal(out, expected) {
-		t.Error("incorrect result")
+	mtf := newMTFDecoderWithRange(5)
+	for i, v := range vectors {
+		sym := mtf.Decode(v.idx)
+		t.Log(mtf)
+		if sym != v.sym {
+			t.Errorf("test %d, symbol mismatch: Decode(%d) = %d, want %d", i, v.idx, sym, v.sym)
+		}
 	}
 }
 
-const helloWorldBZ2Hex = "425a68393141592653594eece83600000251800010400006449080200031064c4101a7a9a580bb9431f8bb9229c28482776741b0"
-
-var helloWorld = []byte("hello world\n")
-
-const thirtyTwoZerosBZ2Hex = "425a6839314159265359b5aa5098000000600040000004200021008283177245385090b5aa5098"
-const oneMBZerosBZ2Hex = "425a683931415926535938571ce50008084000c0040008200030cc0529a60806c4201e2ee48a70a12070ae39ca"
-
-const randBZ2Hex = "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"
-const randHex = "c95138082bdf2b9bfa5b1072b23f729735d42c785eeb94320fb14c265b9c2ca421d01a3db986df1ac2acde5a0e6bf955d6f95e61261540905928e195f1a66644cc7f37281744fff4dc6df35566a494c41a8167151950eb74f5fc45f85ad0e5ed28b49adfe218aa7ec1707e8e1d55825f61f72beda3b4c006b8c9188d7336a5d875329b1b58c27cc4e89ecbae02c7712400c39dd131d2c6de82e2863da51d472bdfb21ecce62cc9cf769ed28aedc7583d755da45a0d90874bda269dd53283a9bdfd05f95fc8e9a304bb338ea1a2111894678c18134f17d31a15d9bfc1237894650f3e715e2548639ecbddb845cfe4a46a7b3a3c540f48629488e8c869f1e9f3f4c552243a8105b20eb8e264994214349dae83b165fd6c2a5b8e83fce09fc0a80d3281c8d53a9a08095bd19cbc1388df23975646ed259e003d39261ee68cbece8bcf32971f7fe7e588e8ba8f5e8597909abaea693836a79a1964050ed910a45a0f13a58cd2d3ae18992c5b23082407fd920d0bf01e33118a017bb5e39f44931346845af52128f7965206759433a346034ea481671f501280067567619f5ecef6cded077f92ed7f3b3ce8e308c80f34ba06939e9303f91b4318c8c1dd4cc223c1f057ac0c91211c629cd30e46ee9ec1d9fd493086b7bc2bc83e33f08749a5d430b0ed4f79d70f481940c9b0930b16321886a0df4fa5a1465d5208c7d3494a7987d9a5e42aa256f0c9523947f8318d0ef0af3d59a45cfc2418d0785c9a548b32b81e7de18be7d55a69a4c156bbb3d7579c0ac8e9c72b24646e54b0d0e8725f8f49fb44ae3c6b9d0287be118586255a90a4a83483ed0328518037e52aa959c5748ed83e13023e532306be98b8288da306bbb040bcf5d92176f84a9306dc6b274b040370b61d71fde58dd6d20e6fee348eae0c54bd0a5a487b2d005f329794f2a902c296af0a4c1f638f63292a1fa18e006c1b1838636f4de71c73635b25660d32e88a0917e1a5677f6a02ca65585b82cbd99fb4badbfa97a585da1e6cadf6737b4ec6ca33f245d66ee6a9fae6785d69b003c17b9fc6ec34fe5824ab8caae5e8e14dc6f9e116e7bf4a60c04388783c8ae929e1b46b3ef3bbe81b38f2fa6da771bf39dfba2374d3d2ed356b8e2c42081d885a91a3afb2f31986d2f9873354c48cf5448492c32e62385af423aa4f83db6d1b2669650379a1134b0a04cbca0862d6f9743c791cbb527d36cd5d1f0fc7f503831c8bd1b7a0ef8ae1a5ed1155dfdd9e32b6bb33138112d3d476b802179cb85a2a6c354ccfed2f31604fbd8d6ec4baf9f1c8454f72c6588c06a7df3178c43a6970bfa02dd6f74cb5ec3b63f9eddaa17db5cbf27fac6de8e57c384afd0954179f7b5690c3bee42abc4fa79b4b12101a9cf5f0b9aecdda945def0bd04163237247d3539850e123fe18139f316fa0256d5bd2faa8"
-
-const oneMBSawtoothBZ2Hex = "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"
-
-const rand2BZ2Hex = "425a6839314159265359d992d0f60000137dfe84020310091c1e280e100e042801099210094806c0110002e70806402000546034000034000000f2830000032000d3403264049270eb7a9280d308ca06ad28f6981bee1bf8160727c7364510d73a1e123083421b63f031f63993a0f40051fbf177245385090d992d0f60"
-const rand2Hex = "92d5652616ac444a4a04af1a8a3964aca0450d43d6cf233bd03233f4ba92f8719e6c2a2bd4f5f88db07ecd0da3a33b263483db9b2c158786ad6363be35d17335ba"
-
-const rand3BZ2Hex = "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"
-const rand3Hex = "1744b384d68c042371244e13500d4bfb98c6244e3d71a5b700224420b59c593553f33bd786e3d0ce31626f511bc985f59d1a88aa38ba8ad6218d306abee60dd9172540232b95be1af146c69e72e5fde667a090dc3f93bdc5c5af0ab80acdbaa7a505f628c59dc0247b31a439cacf5010a94376d71521df08c178b02fb96fdb1809144ea38c68536187c53201fea8631fb0a880b4451ccdca7cc61f6aafca21cc7449d920599db61789ac3b1e164b3390124f95022aeea39ccca3ec1053f4fa10de2978e2861ea58e477085c2220021a0927aa94c5d0006b5055abba340e4f9eba22e969978dfd18e278a8b89d877328ae34268bc0174cfe211954c0036f078025217d1269fac1932a03b05a0b616012271bbe1fb554171c7a59b196d8a4479f45a77931b5d97aaf6c0c673cbe597b79b96e2a0c1eae2e66e46ccc8c85798e23ffe972ebdaa3f6caea243c004e60321eb47cd79137d78fd0613be606feacc5b3637bdc96a89c13746db8cad886f3ccf912b2178c823bcac395f06d28080269bdca2debf3419c66c690fd1adcfbd53e32e79443d7a42511a84cb22ca94fffad9149275a075b2f8ae0b021dcde9bf62b102db920733b897560518b06e1ad7f4b03458493ddaa7f4fa2c1609f7a1735aeeb1b3e2cea3ab45fc376323cc91873b7e9c90d07c192e38d3f5dfc9bfab1fd821c854da9e607ea596c391c7ec4161c6c4493929a8176badaa5a5af7211c623f29643a937677d3df0da9266181b7c4da5dd40376db677fe8f4a1dc456adf6f33c1e37cec471dd318c2647644fe52f93707a77da7d1702380a80e14cc0fdce7bf2eed48a529090bae0388ee277ce6c7018c5fb00b88362554362205c641f0d0fab94fd5b8357b5ff08b207fee023709bc126ec90cfb17c006754638f8186aaeb1265e80be0c1189ec07d01d5f6f96cb9ce82744147d18490de7dc72862f42f024a16968891a356f5e7e0e695d8c933ba5b5e43ad4c4ade5399bc2cae9bb6189b7870d7f22956194d277f28b10e01c10c6ffe3e065f7e2d6d056aa790db5649ca84dc64c35566c0af1b68c32b5b7874aaa66467afa44f40e9a0846a07ae75360a641dd2acc69d93219b2891f190621511e62a27f5e4fbe641ece1fa234fc7e9a74f48d2a760d82160d9540f649256b169d1fed6fbefdc491126530f3cbad7913e19fbd7aa53b1e243fbf28d5f38c10ebd77c8b986775975cc1d619efb27cdcd733fa1ca36cffe9c0a33cc9f02463c91a886601fd349efee85ef1462065ef9bd2c8f533220ad93138b8382d5938103ab25b2d9af8ae106e1211eb9b18793fba033900c809c02cd6d17e2f3e6fc84dae873411f8e87c3f0a8f1765b7825d185ce3730f299c3028d4a62da9ee95c2b870fb70c79370d485f9d5d9acb78926d20444033d960524d2776dc31988ec7c0dbf23b9905d"
-
-const (
-	digits = iota
-	twain
-	random
+var (
+	digits = mustLoadFile("testdata/e.txt.bz2")
+	twain  = mustLoadFile("testdata/Mark.Twain-Tom.Sawyer.txt.bz2")
+	random = mustLoadFile("testdata/random.data.bz2")
 )
 
-var testfiles = []string{
-	// Digits is the digits of the irrational number e. Its decimal representation
-	// does not repeat, but there are only 10 possible digits, so it should be
-	// reasonably compressible.
-	digits: "testdata/e.txt.bz2",
-	// Twain is Mark Twain's classic English novel.
-	twain: "testdata/Mark.Twain-Tom.Sawyer.txt.bz2",
-	// 16KB of random data from /dev/urandom
-	random: "testdata/random.data.bz2",
-}
-
-func benchmarkDecode(b *testing.B, testfile int) {
-	compressed, err := ioutil.ReadFile(testfiles[testfile])
+func benchmarkDecode(b *testing.B, compressed []byte) {
+	// Determine the uncompressed size of testfile.
+	uncompressedSize, err := io.Copy(ioutil.Discard, NewReader(bytes.NewReader(compressed)))
 	if err != nil {
 		b.Fatal(err)
 	}
-	b.SetBytes(int64(len(compressed)))
+
+	b.SetBytes(uncompressedSize)
+	b.ReportAllocs()
+	b.ResetTimer()
+
 	for i := 0; i < b.N; i++ {
 		r := bytes.NewReader(compressed)
 		io.Copy(ioutil.Discard, NewReader(r))
@@ -202,222 +230,3 @@ func benchmarkDecode(b *testing.B, testfile int) {
 func BenchmarkDecodeDigits(b *testing.B) { benchmarkDecode(b, digits) }
 func BenchmarkDecodeTwain(b *testing.B)  { benchmarkDecode(b, twain) }
 func BenchmarkDecodeRand(b *testing.B)   { benchmarkDecode(b, random) }
-
-func TestBufferOverrun(t *testing.T) {
-	// Tests https://golang.org/issue/5747.
-	buffer := bytes.NewReader([]byte(bufferOverrunBase64))
-	decoder := base64.NewDecoder(base64.StdEncoding, buffer)
-	decompressor := NewReader(decoder)
-	// This shouldn't panic.
-	ioutil.ReadAll(decompressor)
-}
-
-func TestOutOfRangeSelector(t *testing.T) {
-	// Tests https://golang.org/issue/8363.
-	buffer := bytes.NewReader(outOfRangeSelector)
-	decompressor := NewReader(buffer)
-	// This shouldn't panic.
-	ioutil.ReadAll(decompressor)
-}
-
-func TestMTF(t *testing.T) {
-	mtf := newMTFDecoderWithRange(5)
-
-	// 0 1 2 3 4
-	expect := byte(1)
-	x := mtf.Decode(1)
-	if x != expect {
-		t.Errorf("expected %v, got %v", expect, x)
-	}
-
-	// 1 0 2 3 4
-	x = mtf.Decode(0)
-	if x != expect {
-		t.Errorf("expected %v, got %v", expect, x)
-	}
-
-	// 1 0 2 3 4
-	expect = byte(0)
-	x = mtf.Decode(1)
-	if x != expect {
-		t.Errorf("expected %v, got %v", expect, x)
-	}
-
-	// 0 1 2 3 4
-	expect = byte(4)
-	x = mtf.Decode(4)
-	if x != expect {
-		t.Errorf("expected %v, got %v", expect, x)
-	}
-
-	// 4 0 1 2 3
-	expect = byte(0)
-	x = mtf.Decode(1)
-	if x != expect {
-		t.Errorf("expected %v, got %v", expect, x)
-	}
-}
-
-var bufferOverrunBase64 string = `
-QlpoNTFBWSZTWTzyiGcACMP/////////////////////////////////3/7f3///
-////4N/fCZODak2Xo44GIHZgkGzDRbFAuwAAKoFV7T6AO6qwA6APb6s2rOoAkAAD
-oACUoDtndh0iQAPkAAAAaPWihQoCgr5t97Obju21ChQB0NBm3RbA7apXrRoBooAA
-AhA+IAHWl2Us3O7t9yieb3udvd76+4+fd33nd3HO1bVvfcGRne6+3vfPvfc++995
-w7k973eJhasLVec970tzDNXdX28LoPXZ3H3K9z0s5ufWAfes49d5594c3dUYtI+2
-+h1dvtpRa+uvrVEAG9bl893RVEN7cWvroSqWjPMGgAQi7Gq8TJSgKKdjKFBIB9Ae
-LqWxleu715eXe7ml9e5098Z6G1vr7t1QZ6ot76YzPd3j7333t2ql2Chm7XrA9ICQ
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-EMEwRpoAAAABMmhoAAjBNNAaCMhponpoGpgJpk9TEyp6niGKZkAaAEfqMQ09U80p
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-4QmLmkHt7LxB2pAczUO+T2O9bHEw/HWw+dYf2MoRDUw=
-`
-
-var outOfRangeSelector = []byte{
-	0x42, 0x5a, 0x68, 0x39, 0x31, 0x41, 0x59, 0x26,
-	0x53, 0x59, 0x4e, 0xec, 0xe8, 0x36, 0x00, 0x00,
-	0x02, 0x51, 0x80, 0x00, 0x10, 0x40, 0x00, 0x06,
-	0x44, 0x90, 0x80, 0x20, 0x00, 0x31, 0x06, 0x4c,
-	0x41, 0x01, 0xa7, 0xa9, 0xa5, 0x80, 0xbb, 0x94,
-	0x31, 0x17, 0x72, 0x45, 0x38, 0x50, 0x90, 0x00,
-	0x00, 0x00, 0x00,
-}
diff --git a/libgo/go/compress/bzip2/testdata/Mark.Twain-Tom.Sawyer.txt.bz2 b/libgo/go/compress/bzip2/testdata/Mark.Twain-Tom.Sawyer.txt.bz2
index 0bd61a6d4e3..eac2b0571b8 100644
--- a/libgo/go/compress/bzip2/testdata/Mark.Twain-Tom.Sawyer.txt.bz2
+++ b/libgo/go/compress/bzip2/testdata/Mark.Twain-Tom.Sawyer.txt.bz2
diff --git a/libgo/go/compress/bzip2/testdata/fail-issue5747.bz2 b/libgo/go/compress/bzip2/testdata/fail-issue5747.bz2
new file mode 100644
index 00000000000..2bf2b6ad99f
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/fail-issue5747.bz2
diff --git a/libgo/go/compress/bzip2/testdata/pass-random1.bin b/libgo/go/compress/bzip2/testdata/pass-random1.bin
new file mode 100644
index 00000000000..6e178792e1e
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/pass-random1.bin
diff --git a/libgo/go/compress/bzip2/testdata/pass-random1.bz2 b/libgo/go/compress/bzip2/testdata/pass-random1.bz2
new file mode 100644
index 00000000000..f6a9dc71667
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/pass-random1.bz2
diff --git a/libgo/go/compress/bzip2/testdata/pass-random2.bin b/libgo/go/compress/bzip2/testdata/pass-random2.bin
new file mode 100644
index 00000000000..f152d40064f
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/pass-random2.bin
@@ -0,0 +1 @@
+��e&�DJJ��9d��E
C��#;�23����q�l*+�����~�
��;&4�ۛ,���cc�5�s5�
\ No newline at end of file
diff --git a/libgo/go/compress/bzip2/testdata/pass-random2.bz2 b/libgo/go/compress/bzip2/testdata/pass-random2.bz2
new file mode 100644
index 00000000000..91ef775ccd9
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/pass-random2.bz2
diff --git a/libgo/go/compress/bzip2/testdata/pass-sawtooth.bz2 b/libgo/go/compress/bzip2/testdata/pass-sawtooth.bz2
new file mode 100644
index 00000000000..579a3782b65
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/pass-sawtooth.bz2
diff --git a/libgo/go/compress/bzip2/testdata/random.data.bz2 b/libgo/go/compress/bzip2/testdata/random.data.bz2
new file mode 100644
index 00000000000..1ef23001668
--- /dev/null
+++ b/libgo/go/compress/bzip2/testdata/random.data.bz2
diff --git a/libgo/go/compress/flate/copy.go b/libgo/go/compress/flate/copy.go
deleted file mode 100644
index a3200a8f49e..00000000000
--- a/libgo/go/compress/flate/copy.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package flate
-
-// forwardCopy is like the built-in copy function except that it always goes
-// forward from the start, even if the dst and src overlap.
-// It is equivalent to:
-//   for i := 0; i < n; i++ {
-//     mem[dst+i] = mem[src+i]
-//   }
-func forwardCopy(mem []byte, dst, src, n int) {
-	if dst <= src {
-		copy(mem[dst:dst+n], mem[src:src+n])
-		return
-	}
-	for {
-		if dst >= src+n {
-			copy(mem[dst:dst+n], mem[src:src+n])
-			return
-		}
-		// There is some forward overlap.  The destination
-		// will be filled with a repeated pattern of mem[src:src+k].
-		// We copy one instance of the pattern here, then repeat.
-		// Each time around this loop k will double.
-		k := dst - src
-		copy(mem[dst:dst+k], mem[src:src+k])
-		n -= k
-		dst += k
-	}
-}
diff --git a/libgo/go/compress/flate/copy_test.go b/libgo/go/compress/flate/copy_test.go
deleted file mode 100644
index 2011b1547c9..00000000000
--- a/libgo/go/compress/flate/copy_test.go
+++ /dev/null
@@ -1,54 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package flate
-
-import (
-	"testing"
-)
-
-func TestForwardCopy(t *testing.T) {
-	testCases := []struct {
-		dst0, dst1 int
-		src0, src1 int
-		want       string
-	}{
-		{0, 9, 0, 9, "012345678"},
-		{0, 5, 4, 9, "45678"},
-		{4, 9, 0, 5, "01230"},
-		{1, 6, 3, 8, "34567"},
-		{3, 8, 1, 6, "12121"},
-		{0, 9, 3, 6, "345"},
-		{3, 6, 0, 9, "012"},
-		{1, 6, 0, 9, "00000"},
-		{0, 4, 7, 8, "7"},
-		{0, 1, 6, 8, "6"},
-		{4, 4, 6, 9, ""},
-		{2, 8, 6, 6, ""},
-		{0, 0, 0, 0, ""},
-	}
-	for _, tc := range testCases {
-		b := []byte("0123456789")
-		n := tc.dst1 - tc.dst0
-		if tc.src1-tc.src0 < n {
-			n = tc.src1 - tc.src0
-		}
-		forwardCopy(b, tc.dst0, tc.src0, n)
-		got := string(b[tc.dst0 : tc.dst0+n])
-		if got != tc.want {
-			t.Errorf("dst=b[%d:%d], src=b[%d:%d]: got %q, want %q",
-				tc.dst0, tc.dst1, tc.src0, tc.src1, got, tc.want)
-		}
-		// Check that the bytes outside of dst[:n] were not modified.
-		for i, x := range b {
-			if i >= tc.dst0 && i < tc.dst0+n {
-				continue
-			}
-			if int(x) != '0'+i {
-				t.Errorf("dst=b[%d:%d], src=b[%d:%d]: copy overrun at b[%d]: got '%c', want '%c'",
-					tc.dst0, tc.dst1, tc.src0, tc.src1, i, x, '0'+i)
-			}
-		}
-	}
-}
diff --git a/libgo/go/compress/flate/deflate.go b/libgo/go/compress/flate/deflate.go
index 169a0c7b2eb..8a085ba3474 100644
--- a/libgo/go/compress/flate/deflate.go
+++ b/libgo/go/compress/flate/deflate.go
@@ -13,54 +13,65 @@ import (
 const (
 	NoCompression      = 0
 	BestSpeed          = 1
-	fastCompression    = 3
 	BestCompression    = 9
 	DefaultCompression = -1
-	logWindowSize      = 15
-	windowSize         = 1 << logWindowSize
-	windowMask         = windowSize - 1
-	logMaxOffsetSize   = 15  // Standard DEFLATE
-	minMatchLength     = 3   // The smallest match that the compressor looks for
-	maxMatchLength     = 258 // The longest match for the compressor
-	minOffsetSize      = 1   // The shortest offset that makes any sense
-
-	// The maximum number of tokens we put into a single flat block, just to
+	HuffmanOnly        = -2 // Disables match search and only does Huffman entropy reduction.
+)
+
+const (
+	logWindowSize = 15
+	windowSize    = 1 << logWindowSize
+	windowMask    = windowSize - 1
+
+	// The LZ77 step produces a sequence of literal tokens and <length, offset>
+	// pair tokens. The offset is also known as distance. The underlying wire
+	// format limits the range of lengths and offsets. For example, there are
+	// 256 legitimate lengths: those in the range [3, 258]. This package's
+	// compressor uses a higher minimum match length, enabling optimizations
+	// such as finding matches via 32-bit loads and compares.
+	baseMatchLength = 3       // The smallest match length per the RFC section 3.2.5
+	minMatchLength  = 4       // The smallest match length that the compressor actually emits
+	maxMatchLength  = 258     // The largest match length
+	baseMatchOffset = 1       // The smallest match offset
+	maxMatchOffset  = 1 << 15 // The largest match offset
+
+	// The maximum number of tokens we put into a single flate block, just to
 	// stop things from getting too large.
 	maxFlateBlockTokens = 1 << 14
 	maxStoreBlockSize   = 65535
-	hashBits            = 17
+	hashBits            = 17 // After 17 performance degrades
 	hashSize            = 1 << hashBits
 	hashMask            = (1 << hashBits) - 1
-	hashShift           = (hashBits + minMatchLength - 1) / minMatchLength
 	maxHashOffset       = 1 << 24
 
 	skipNever = math.MaxInt32
 )
 
 type compressionLevel struct {
-	good, lazy, nice, chain, fastSkipHashing int
+	level, good, lazy, nice, chain, fastSkipHashing int
 }
 
 var levels = []compressionLevel{
-	{}, // 0
-	// For levels 1-3 we don't bother trying with lazy matches
-	{3, 0, 8, 4, 4},
-	{3, 0, 16, 8, 5},
-	{3, 0, 32, 32, 6},
+	{0, 0, 0, 0, 0, 0}, // NoCompression.
+	{1, 0, 0, 0, 0, 0}, // BestSpeed uses a custom algorithm; see deflatefast.go.
+	// For levels 2-3 we don't bother trying with lazy matches.
+	{2, 4, 0, 16, 8, 5},
+	{3, 4, 0, 32, 32, 6},
 	// Levels 4-9 use increasingly more lazy matching
 	// and increasingly stringent conditions for "good enough".
-	{4, 4, 16, 16, skipNever},
-	{8, 16, 32, 32, skipNever},
-	{8, 16, 128, 128, skipNever},
-	{8, 32, 128, 256, skipNever},
-	{32, 128, 258, 1024, skipNever},
-	{32, 258, 258, 4096, skipNever},
+	{4, 4, 4, 16, 16, skipNever},
+	{5, 8, 16, 32, 32, skipNever},
+	{6, 8, 16, 128, 128, skipNever},
+	{7, 8, 32, 128, 256, skipNever},
+	{8, 32, 128, 258, 1024, skipNever},
+	{9, 32, 258, 258, 4096, skipNever},
 }
 
 type compressor struct {
 	compressionLevel
 
-	w *huffmanBitWriter
+	w          *huffmanBitWriter
+	bulkHasher func([]byte, []uint32)
 
 	// compression algorithm
 	fill func(*compressor, []byte) int // copy data to window
@@ -73,8 +84,8 @@ type compressor struct {
 	// hashPrev[hashHead[hashValue] & windowMask] contains the previous index
 	// with the same hash value.
 	chainHead  int
-	hashHead   []int
-	hashPrev   []int
+	hashHead   [hashSize]uint32
+	hashPrev   [windowSize]uint32
 	hashOffset int
 
 	// input window: unprocessed data is window[index:windowEnd]
@@ -90,9 +101,12 @@ type compressor struct {
 	// deflate state
 	length         int
 	offset         int
-	hash           int
+	hash           uint32
 	maxInsertIndex int
 	err            error
+
+	// hashMatch must be able to contain hashes for the maximum match length.
+	hashMatch [maxMatchLength - 1]uint32
 }
 
 func (d *compressor) fillDeflate(b []byte) int {
@@ -112,15 +126,15 @@ func (d *compressor) fillDeflate(b []byte) int {
 			d.hashOffset -= delta
 			d.chainHead -= delta
 			for i, v := range d.hashPrev {
-				if v > delta {
-					d.hashPrev[i] -= delta
+				if int(v) > delta {
+					d.hashPrev[i] = uint32(int(v) - delta)
 				} else {
 					d.hashPrev[i] = 0
 				}
 			}
 			for i, v := range d.hashHead {
-				if v > delta {
-					d.hashHead[i] -= delta
+				if int(v) > delta {
+					d.hashHead[i] = uint32(int(v) - delta)
 				} else {
 					d.hashHead[i] = 0
 				}
@@ -132,19 +146,74 @@ func (d *compressor) fillDeflate(b []byte) int {
 	return n
 }
 
-func (d *compressor) writeBlock(tokens []token, index int, eof bool) error {
-	if index > 0 || eof {
+func (d *compressor) writeBlock(tokens []token, index int) error {
+	if index > 0 {
 		var window []byte
 		if d.blockStart <= index {
 			window = d.window[d.blockStart:index]
 		}
 		d.blockStart = index
-		d.w.writeBlock(tokens, eof, window)
+		d.w.writeBlock(tokens, false, window)
 		return d.w.err
 	}
 	return nil
 }
 
+// fillWindow will fill the current window with the supplied
+// dictionary and calculate all hashes.
+// This is much faster than doing a full encode.
+// Should only be used after a reset.
+func (d *compressor) fillWindow(b []byte) {
+	// Do not fill window if we are in store-only mode.
+	if d.compressionLevel.level < 2 {
+		return
+	}
+	if d.index != 0 || d.windowEnd != 0 {
+		panic("internal error: fillWindow called with stale data")
+	}
+
+	// If we are given too much, cut it.
+	if len(b) > windowSize {
+		b = b[len(b)-windowSize:]
+	}
+	// Add all to window.
+	n := copy(d.window, b)
+
+	// Calculate 256 hashes at the time (more L1 cache hits)
+	loops := (n + 256 - minMatchLength) / 256
+	for j := 0; j < loops; j++ {
+		index := j * 256
+		end := index + 256 + minMatchLength - 1
+		if end > n {
+			end = n
+		}
+		toCheck := d.window[index:end]
+		dstSize := len(toCheck) - minMatchLength + 1
+
+		if dstSize <= 0 {
+			continue
+		}
+
+		dst := d.hashMatch[:dstSize]
+		d.bulkHasher(toCheck, dst)
+		var newH uint32
+		for i, val := range dst {
+			di := i + index
+			newH = val
+			hh := &d.hashHead[newH&hashMask]
+			// Get previous value with the same hash.
+			// Our chain should point to the previous value.
+			d.hashPrev[di&windowMask] = *hh
+			// Set the head of the hash chain to us.
+			*hh = uint32(di + d.hashOffset)
+		}
+		d.hash = newH
+	}
+	// Update window information.
+	d.windowEnd = n
+	d.index = n
+}
+
 // Try to find a match starting at index whose length is greater than prevSize.
 // We only look at chainCount possibilities before giving up.
 func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead int) (length, offset int, ok bool) {
@@ -168,20 +237,15 @@ func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead
 		tries >>= 2
 	}
 
-	w0 := win[pos]
-	w1 := win[pos+1]
 	wEnd := win[pos+length]
+	wPos := win[pos:]
 	minIndex := pos - windowSize
 
 	for i := prevHead; tries > 0; tries-- {
-		if w0 == win[i] && w1 == win[i+1] && wEnd == win[i+length] {
-			// The hash function ensures that if win[i] and win[i+1] match, win[i+2] matches
+		if wEnd == win[i+length] {
+			n := matchLen(win[i:], wPos, minMatchLook)
 
-			n := 3
-			for pos+n < len(win) && win[i+n] == win[pos+n] {
-				n++
-			}
-			if n > length && (n > 3 || pos-i <= 4096) {
+			if n > length && (n > minMatchLength || pos-i <= 4096) {
 				length = n
 				offset = pos - i
 				ok = true
@@ -196,7 +260,8 @@ func (d *compressor) findMatch(pos int, prevHead int, prevLength int, lookahead
 			// hashPrev[i & windowMask] has already been overwritten, so stop now.
 			break
 		}
-		if i = d.hashPrev[i&windowMask] - d.hashOffset; i < minIndex || i < 0 {
+		i = int(d.hashPrev[i&windowMask]) - d.hashOffset
+		if i < minIndex || i < 0 {
 			break
 		}
 	}
@@ -211,9 +276,84 @@ func (d *compressor) writeStoredBlock(buf []byte) error {
 	return d.w.err
 }
 
+const hashmul = 0x1e35a7bd
+
+// hash4 returns a hash representation of the first 4 bytes
+// of the supplied slice.
+// The caller must ensure that len(b) >= 4.
+func hash4(b []byte) uint32 {
+	return ((uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24) * hashmul) >> (32 - hashBits)
+}
+
+// bulkHash4 will compute hashes using the same
+// algorithm as hash4
+func bulkHash4(b []byte, dst []uint32) {
+	if len(b) < minMatchLength {
+		return
+	}
+	hb := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+	dst[0] = (hb * hashmul) >> (32 - hashBits)
+	end := len(b) - minMatchLength + 1
+	for i := 1; i < end; i++ {
+		hb = (hb << 8) | uint32(b[i+3])
+		dst[i] = (hb * hashmul) >> (32 - hashBits)
+	}
+}
+
+// matchLen returns the number of matching bytes in a and b
+// up to length 'max'. Both slices must be at least 'max'
+// bytes in size.
+func matchLen(a, b []byte, max int) int {
+	a = a[:max]
+	b = b[:len(a)]
+	for i, av := range a {
+		if b[i] != av {
+			return i
+		}
+	}
+	return max
+}
+
+// encSpeed will compress and store the currently added data,
+// if enough has been accumulated or we at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) encSpeed() {
+	// We only compress if we have maxStoreBlockSize.
+	if d.windowEnd < maxStoreBlockSize {
+		if !d.sync {
+			return
+		}
+
+		// Handle small sizes.
+		if d.windowEnd < 128 {
+			switch {
+			case d.windowEnd == 0:
+				return
+			case d.windowEnd <= 16:
+				d.err = d.writeStoredBlock(d.window[:d.windowEnd])
+			default:
+				d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+				d.err = d.w.err
+			}
+			d.windowEnd = 0
+			return
+		}
+
+	}
+	// Encode the block.
+	d.tokens = encodeBestSpeed(d.tokens[:0], d.window[:d.windowEnd])
+
+	// If we removed less than 1/16th, Huffman compress the block.
+	if len(d.tokens) > d.windowEnd-(d.windowEnd>>4) {
+		d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+	} else {
+		d.w.writeBlockDynamic(d.tokens, false, d.window[:d.windowEnd])
+	}
+	d.err = d.w.err
+	d.windowEnd = 0
+}
+
 func (d *compressor) initDeflate() {
-	d.hashHead = make([]int, hashSize)
-	d.hashPrev = make([]int, windowSize)
 	d.window = make([]byte, 2*windowSize)
 	d.hashOffset = 1
 	d.tokens = make([]token, 0, maxFlateBlockTokens+1)
@@ -223,6 +363,7 @@ func (d *compressor) initDeflate() {
 	d.index = 0
 	d.hash = 0
 	d.chainHead = -1
+	d.bulkHasher = bulkHash4
 }
 
 func (d *compressor) deflate() {
@@ -232,7 +373,7 @@ func (d *compressor) deflate() {
 
 	d.maxInsertIndex = d.windowEnd - (minMatchLength - 1)
 	if d.index < d.maxInsertIndex {
-		d.hash = int(d.window[d.index])<<hashShift + int(d.window[d.index+1])
+		d.hash = hash4(d.window[d.index : d.index+minMatchLength])
 	}
 
 Loop:
@@ -256,7 +397,7 @@ Loop:
 					d.byteAvailable = false
 				}
 				if len(d.tokens) > 0 {
-					if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+					if d.err = d.writeBlock(d.tokens, d.index); d.err != nil {
 						return
 					}
 					d.tokens = d.tokens[:0]
@@ -266,10 +407,11 @@ Loop:
 		}
 		if d.index < d.maxInsertIndex {
 			// Update the hash
-			d.hash = (d.hash<<hashShift + int(d.window[d.index+2])) & hashMask
-			d.chainHead = d.hashHead[d.hash]
-			d.hashPrev[d.index&windowMask] = d.chainHead
-			d.hashHead[d.hash] = d.index + d.hashOffset
+			d.hash = hash4(d.window[d.index : d.index+minMatchLength])
+			hh := &d.hashHead[d.hash&hashMask]
+			d.chainHead = int(*hh)
+			d.hashPrev[d.index&windowMask] = uint32(d.chainHead)
+			*hh = uint32(d.index + d.hashOffset)
 		}
 		prevLength := d.length
 		prevOffset := d.offset
@@ -293,9 +435,9 @@ Loop:
 			// There was a match at the previous step, and the current match is
 			// not better. Output the previous match.
 			if d.fastSkipHashing != skipNever {
-				d.tokens = append(d.tokens, matchToken(uint32(d.length-minMatchLength), uint32(d.offset-minOffsetSize)))
+				d.tokens = append(d.tokens, matchToken(uint32(d.length-baseMatchLength), uint32(d.offset-baseMatchOffset)))
 			} else {
-				d.tokens = append(d.tokens, matchToken(uint32(prevLength-minMatchLength), uint32(prevOffset-minOffsetSize)))
+				d.tokens = append(d.tokens, matchToken(uint32(prevLength-baseMatchLength), uint32(prevOffset-baseMatchOffset)))
 			}
 			// Insert in the hash table all strings up to the end of the match.
 			// index and index-1 are already inserted. If there is not enough
@@ -310,12 +452,13 @@ Loop:
 				}
 				for d.index++; d.index < newIndex; d.index++ {
 					if d.index < d.maxInsertIndex {
-						d.hash = (d.hash<<hashShift + int(d.window[d.index+2])) & hashMask
+						d.hash = hash4(d.window[d.index : d.index+minMatchLength])
 						// Get previous value with the same hash.
 						// Our chain should point to the previous value.
-						d.hashPrev[d.index&windowMask] = d.hashHead[d.hash]
+						hh := &d.hashHead[d.hash&hashMask]
+						d.hashPrev[d.index&windowMask] = *hh
 						// Set the head of the hash chain to us.
-						d.hashHead[d.hash] = d.index + d.hashOffset
+						*hh = uint32(d.index + d.hashOffset)
 					}
 				}
 				if d.fastSkipHashing == skipNever {
@@ -327,12 +470,12 @@ Loop:
 				// item into the table.
 				d.index += d.length
 				if d.index < d.maxInsertIndex {
-					d.hash = (int(d.window[d.index])<<hashShift + int(d.window[d.index+1]))
+					d.hash = hash4(d.window[d.index : d.index+minMatchLength])
 				}
 			}
 			if len(d.tokens) == maxFlateBlockTokens {
 				// The block includes the current character
-				if d.err = d.writeBlock(d.tokens, d.index, false); d.err != nil {
+				if d.err = d.writeBlock(d.tokens, d.index); d.err != nil {
 					return
 				}
 				d.tokens = d.tokens[:0]
@@ -345,7 +488,7 @@ Loop:
 				}
 				d.tokens = append(d.tokens, literalToken(uint32(d.window[i])))
 				if len(d.tokens) == maxFlateBlockTokens {
-					if d.err = d.writeBlock(d.tokens, i+1, false); d.err != nil {
+					if d.err = d.writeBlock(d.tokens, i+1); d.err != nil {
 						return
 					}
 					d.tokens = d.tokens[:0]
@@ -372,17 +515,37 @@ func (d *compressor) store() {
 	d.windowEnd = 0
 }
 
+// storeHuff compresses and stores the currently added data
+// when the d.window is full or we are at the end of the stream.
+// Any error that occurred will be in d.err
+func (d *compressor) storeHuff() {
+	if d.windowEnd < len(d.window) && !d.sync || d.windowEnd == 0 {
+		return
+	}
+	d.w.writeBlockHuff(false, d.window[:d.windowEnd])
+	d.err = d.w.err
+	d.windowEnd = 0
+}
+
 func (d *compressor) write(b []byte) (n int, err error) {
+	if d.err != nil {
+		return 0, d.err
+	}
 	n = len(b)
-	b = b[d.fill(d, b):]
 	for len(b) > 0 {
 		d.step(d)
 		b = b[d.fill(d, b):]
+		if d.err != nil {
+			return 0, d.err
+		}
 	}
-	return n, d.err
+	return n, nil
 }
 
 func (d *compressor) syncFlush() error {
+	if d.err != nil {
+		return d.err
+	}
 	d.sync = true
 	d.step(d)
 	if d.err == nil {
@@ -402,56 +565,51 @@ func (d *compressor) init(w io.Writer, level int) (err error) {
 		d.window = make([]byte, maxStoreBlockSize)
 		d.fill = (*compressor).fillStore
 		d.step = (*compressor).store
+	case level == HuffmanOnly:
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillStore
+		d.step = (*compressor).storeHuff
+	case level == BestSpeed:
+		d.compressionLevel = levels[level]
+		d.window = make([]byte, maxStoreBlockSize)
+		d.fill = (*compressor).fillStore
+		d.step = (*compressor).encSpeed
+		d.tokens = make([]token, maxStoreBlockSize)
 	case level == DefaultCompression:
 		level = 6
 		fallthrough
-	case 1 <= level && level <= 9:
+	case 2 <= level && level <= 9:
 		d.compressionLevel = levels[level]
 		d.initDeflate()
 		d.fill = (*compressor).fillDeflate
 		d.step = (*compressor).deflate
 	default:
-		return fmt.Errorf("flate: invalid compression level %d: want value in range [-1, 9]", level)
+		return fmt.Errorf("flate: invalid compression level %d: want value in range [-2, 9]", level)
 	}
 	return nil
 }
 
-var zeroes [32]int
-var bzeroes [256]byte
-
 func (d *compressor) reset(w io.Writer) {
 	d.w.reset(w)
 	d.sync = false
 	d.err = nil
-	switch d.compressionLevel.chain {
-	case 0:
-		// level was NoCompression.
-		for i := range d.window {
-			d.window[i] = 0
-		}
+	switch d.compressionLevel.level {
+	case NoCompression:
+		d.windowEnd = 0
+	case BestSpeed:
 		d.windowEnd = 0
+		d.tokens = d.tokens[:0]
 	default:
 		d.chainHead = -1
-		for s := d.hashHead; len(s) > 0; {
-			n := copy(s, zeroes[:])
-			s = s[n:]
+		for i := range d.hashHead {
+			d.hashHead[i] = 0
 		}
-		for s := d.hashPrev; len(s) > 0; s = s[len(zeroes):] {
-			copy(s, zeroes[:])
+		for i := range d.hashPrev {
+			d.hashPrev[i] = 0
 		}
 		d.hashOffset = 1
-
 		d.index, d.windowEnd = 0, 0
-		for s := d.window; len(s) > 0; {
-			n := copy(s, bzeroes[:])
-			s = s[n:]
-		}
 		d.blockStart, d.byteAvailable = 0, false
-
-		d.tokens = d.tokens[:maxFlateBlockTokens+1]
-		for i := 0; i <= maxFlateBlockTokens; i++ {
-			d.tokens[i] = 0
-		}
 		d.tokens = d.tokens[:0]
 		d.length = minMatchLength - 1
 		d.offset = 0
@@ -461,6 +619,9 @@ func (d *compressor) reset(w io.Writer) {
 }
 
 func (d *compressor) close() error {
+	if d.err != nil {
+		return d.err
+	}
 	d.sync = true
 	d.step(d)
 	if d.err != nil {
@@ -477,10 +638,14 @@ func (d *compressor) close() error {
 // Following zlib, levels range from 1 (BestSpeed) to 9 (BestCompression);
 // higher levels typically run slower but compress more. Level 0
 // (NoCompression) does not attempt any compression; it only adds the
-// necessary DEFLATE framing. Level -1 (DefaultCompression) uses the default
-// compression level.
+// necessary DEFLATE framing.
+// Level -1 (DefaultCompression) uses the default compression level.
+// Level -2 (HuffmanOnly) will use Huffman compression only, giving
+// a very fast compression for all types of input, but sacrificing considerable
+// compression efficiency.
 //
-// If level is in the range [-1, 9] then the error returned will be nil.
+//
+// If level is in the range [-2, 9] then the error returned will be nil.
 // Otherwise the error returned will be non-nil.
 func NewWriter(w io.Writer, level int) (*Writer, error) {
 	var dw Writer
@@ -491,34 +656,28 @@ func NewWriter(w io.Writer, level int) (*Writer, error) {
 }
 
 // NewWriterDict is like NewWriter but initializes the new
-// Writer with a preset dictionary.  The returned Writer behaves
+// Writer with a preset dictionary. The returned Writer behaves
 // as if the dictionary had been written to it without producing
-// any compressed output.  The compressed data written to w
+// any compressed output. The compressed data written to w
 // can only be decompressed by a Reader initialized with the
 // same dictionary.
 func NewWriterDict(w io.Writer, level int, dict []byte) (*Writer, error) {
-	dw := &dictWriter{w, false}
+	dw := &dictWriter{w}
 	zw, err := NewWriter(dw, level)
 	if err != nil {
 		return nil, err
 	}
-	zw.Write(dict)
-	zw.Flush()
-	dw.enabled = true
+	zw.d.fillWindow(dict)
 	zw.dict = append(zw.dict, dict...) // duplicate dictionary for Reset method.
 	return zw, err
 }
 
 type dictWriter struct {
-	w       io.Writer
-	enabled bool
+	w io.Writer
 }
 
 func (w *dictWriter) Write(b []byte) (n int, err error) {
-	if w.enabled {
-		return w.w.Write(b)
-	}
-	return len(b), nil
+	return w.w.Write(b)
 }
 
 // A Writer takes data written to it and writes the compressed
@@ -560,10 +719,7 @@ func (w *Writer) Reset(dst io.Writer) {
 		// w was created with NewWriterDict
 		dw.w = dst
 		w.d.reset(dw)
-		dw.enabled = false
-		w.Write(w.dict)
-		w.Flush()
-		dw.enabled = true
+		w.d.fillWindow(w.dict)
 	} else {
 		// w was created with NewWriter
 		w.d.reset(dst)
diff --git a/libgo/go/compress/flate/deflate_test.go b/libgo/go/compress/flate/deflate_test.go
index 72bc6652c89..27a3b3823a6 100644
--- a/libgo/go/compress/flate/deflate_test.go
+++ b/libgo/go/compress/flate/deflate_test.go
@@ -42,10 +42,10 @@ var deflateTests = []*deflateTest{
 	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 0,
 		[]byte{0, 8, 0, 247, 255, 17, 17, 17, 17, 17, 17, 17, 17, 1, 0, 0, 255, 255},
 	},
-	{[]byte{}, 1, []byte{1, 0, 0, 255, 255}},
-	{[]byte{0x11}, 1, []byte{18, 4, 4, 0, 0, 255, 255}},
-	{[]byte{0x11, 0x12}, 1, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
-	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 1, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
+	{[]byte{}, 2, []byte{1, 0, 0, 255, 255}},
+	{[]byte{0x11}, 2, []byte{18, 4, 4, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x12}, 2, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
+	{[]byte{0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11}, 2, []byte{18, 132, 2, 64, 0, 0, 0, 255, 255}},
 	{[]byte{}, 9, []byte{1, 0, 0, 255, 255}},
 	{[]byte{0x11}, 9, []byte{18, 4, 4, 0, 0, 255, 255}},
 	{[]byte{0x11, 0x12}, 9, []byte{18, 20, 2, 4, 0, 0, 255, 255}},
@@ -80,6 +80,32 @@ func largeDataChunk() []byte {
 	return result
 }
 
+func TestBulkHash4(t *testing.T) {
+	for _, x := range deflateTests {
+		y := x.out
+		if len(y) < minMatchLength {
+			continue
+		}
+		y = append(y, y...)
+		for j := 4; j < len(y); j++ {
+			y := y[:j]
+			dst := make([]uint32, len(y)-minMatchLength+1)
+			for i := range dst {
+				dst[i] = uint32(i + 100)
+			}
+			bulkHash4(y, dst)
+			for i, got := range dst {
+				want := hash4(y[i:])
+				if got != want && got == uint32(i)+100 {
+					t.Errorf("Len:%d Index:%d, want 0x%08x but not modified", len(y), i, want)
+				} else if got != want {
+					t.Errorf("Len:%d Index:%d, got 0x%08x want:0x%08x", len(y), i, got, want)
+				}
+			}
+		}
+	}
+}
+
 func TestDeflate(t *testing.T) {
 	for _, h := range deflateTests {
 		var buf bytes.Buffer
@@ -91,7 +117,7 @@ func TestDeflate(t *testing.T) {
 		w.Write(h.in)
 		w.Close()
 		if !bytes.Equal(buf.Bytes(), h.out) {
-			t.Errorf("Deflate(%d, %x) = %x, want %x", h.level, h.in, buf.Bytes(), h.out)
+			t.Errorf("Deflate(%d, %x) = \n%#v, want \n%#v", h.level, h.in, buf.Bytes(), h.out)
 		}
 	}
 }
@@ -247,7 +273,7 @@ func testSync(t *testing.T, level int, input []byte, name string) {
 		// not necessarily the case: the write Flush may emit
 		// some extra framing bits that are not necessary
 		// to process to obtain the first half of the uncompressed
-		// data.  The test ran correctly most of the time, because
+		// data. The test ran correctly most of the time, because
 		// the background goroutine had usually read even
 		// those extra bits by now, but it's not a useful thing to
 		// check.
@@ -289,6 +315,9 @@ func testToFromWithLevelAndLimit(t *testing.T, level int, input []byte, name str
 		t.Errorf("level: %d, len(compress(data)) = %d > limit = %d", level, buffer.Len(), limit)
 		return
 	}
+	if limit > 0 {
+		t.Logf("level: %d, size:%.2f%%, %d b\n", level, float64(buffer.Len()*100)/float64(limit), buffer.Len())
+	}
 	r := NewReader(&buffer)
 	out, err := ioutil.ReadAll(r)
 	if err != nil {
@@ -303,15 +332,17 @@ func testToFromWithLevelAndLimit(t *testing.T, level int, input []byte, name str
 	testSync(t, level, input, name)
 }
 
-func testToFromWithLimit(t *testing.T, input []byte, name string, limit [10]int) {
+func testToFromWithLimit(t *testing.T, input []byte, name string, limit [11]int) {
 	for i := 0; i < 10; i++ {
 		testToFromWithLevelAndLimit(t, i, input, name, limit[i])
 	}
+	// Test HuffmanCompression
+	testToFromWithLevelAndLimit(t, -2, input, name, limit[10])
 }
 
 func TestDeflateInflate(t *testing.T) {
 	for i, h := range deflateInflateTests {
-		testToFromWithLimit(t, h.in, fmt.Sprintf("#%d", i), [10]int{})
+		testToFromWithLimit(t, h.in, fmt.Sprintf("#%d", i), [11]int{})
 	}
 }
 
@@ -327,19 +358,19 @@ func TestReverseBits(t *testing.T) {
 type deflateInflateStringTest struct {
 	filename string
 	label    string
-	limit    [10]int
+	limit    [11]int
 }
 
 var deflateInflateStringTests = []deflateInflateStringTest{
 	{
 		"../testdata/e.txt",
 		"2.718281828...",
-		[...]int{100018, 50650, 50960, 51150, 50930, 50790, 50790, 50790, 50790, 50790},
+		[...]int{100018, 50650, 50960, 51150, 50930, 50790, 50790, 50790, 50790, 50790, 43683},
 	},
 	{
 		"../testdata/Mark.Twain-Tom.Sawyer.txt",
 		"Mark.Twain-Tom.Sawyer",
-		[...]int{407330, 187598, 180361, 172974, 169160, 163476, 160936, 160506, 160295, 160295},
+		[...]int{407330, 187598, 180361, 172974, 169160, 163476, 160936, 160506, 160295, 160295, 233460},
 	},
 }
 
@@ -457,6 +488,17 @@ func TestWriterReset(t *testing.T) {
 		// DeepEqual doesn't compare functions.
 		w.d.fill, wref.d.fill = nil, nil
 		w.d.step, wref.d.step = nil, nil
+		w.d.bulkHasher, wref.d.bulkHasher = nil, nil
+		// hashMatch is always overwritten when used.
+		copy(w.d.hashMatch[:], wref.d.hashMatch[:])
+		if len(w.d.tokens) != 0 {
+			t.Errorf("level %d Writer not reset after Reset. %d tokens were present", level, len(w.d.tokens))
+		}
+		// As long as the length is 0, we don't care about the content.
+		w.d.tokens = wref.d.tokens
+
+		// We don't care if there are values in the window, as long as it is at d.index is 0
+		w.d.window = wref.d.window
 		if !reflect.DeepEqual(w, wref) {
 			t.Errorf("level %d Writer not reset after Reset", level)
 		}
@@ -481,7 +523,7 @@ func testResetOutput(t *testing.T, newWriter func(w io.Writer) (*Writer, error))
 		w.Write(b)
 	}
 	w.Close()
-	out1 := buf.String()
+	out1 := buf.Bytes()
 
 	buf2 := new(bytes.Buffer)
 	w.Reset(buf2)
@@ -489,10 +531,103 @@ func testResetOutput(t *testing.T, newWriter func(w io.Writer) (*Writer, error))
 		w.Write(b)
 	}
 	w.Close()
-	out2 := buf2.String()
+	out2 := buf2.Bytes()
 
-	if out1 != out2 {
-		t.Errorf("got %q, expected %q", out2, out1)
+	if len(out1) != len(out2) {
+		t.Errorf("got %d, expected %d bytes", len(out2), len(out1))
+		return
+	}
+	if !bytes.Equal(out1, out2) {
+		mm := 0
+		for i, b := range out1[:len(out2)] {
+			if b != out2[i] {
+				t.Errorf("mismatch index %d: %#02x, expected %#02x", i, out2[i], b)
+			}
+			mm++
+			if mm == 10 {
+				t.Fatal("Stopping")
+			}
+		}
 	}
 	t.Logf("got %d bytes", len(out1))
 }
+
+// TestBestSpeed tests that round-tripping through deflate and then inflate
+// recovers the original input. The Write sizes are near the thresholds in the
+// compressor.encSpeed method (0, 16, 128), as well as near maxStoreBlockSize
+// (65535).
+func TestBestSpeed(t *testing.T) {
+	abc := make([]byte, 128)
+	for i := range abc {
+		abc[i] = byte(i)
+	}
+	abcabc := bytes.Repeat(abc, 131072/len(abc))
+	var want []byte
+
+	testCases := [][]int{
+		{65536, 0},
+		{65536, 1},
+		{65536, 1, 256},
+		{65536, 1, 65536},
+		{65536, 14},
+		{65536, 15},
+		{65536, 16},
+		{65536, 16, 256},
+		{65536, 16, 65536},
+		{65536, 127},
+		{65536, 128},
+		{65536, 128, 256},
+		{65536, 128, 65536},
+		{65536, 129},
+		{65536, 65536, 256},
+		{65536, 65536, 65536},
+	}
+
+	for i, tc := range testCases {
+		for _, firstN := range []int{1, 65534, 65535, 65536, 65537, 131072} {
+			tc[0] = firstN
+		outer:
+			for _, flush := range []bool{false, true} {
+				buf := new(bytes.Buffer)
+				want = want[:0]
+
+				w, err := NewWriter(buf, BestSpeed)
+				if err != nil {
+					t.Errorf("i=%d, firstN=%d, flush=%t: NewWriter: %v", i, firstN, flush, err)
+					continue
+				}
+				for _, n := range tc {
+					want = append(want, abcabc[:n]...)
+					if _, err := w.Write(abcabc[:n]); err != nil {
+						t.Errorf("i=%d, firstN=%d, flush=%t: Write: %v", i, firstN, flush, err)
+						continue outer
+					}
+					if !flush {
+						continue
+					}
+					if err := w.Flush(); err != nil {
+						t.Errorf("i=%d, firstN=%d, flush=%t: Flush: %v", i, firstN, flush, err)
+						continue outer
+					}
+				}
+				if err := w.Close(); err != nil {
+					t.Errorf("i=%d, firstN=%d, flush=%t: Close: %v", i, firstN, flush, err)
+					continue
+				}
+
+				r := NewReader(buf)
+				got, err := ioutil.ReadAll(r)
+				if err != nil {
+					t.Errorf("i=%d, firstN=%d, flush=%t: ReadAll: %v", i, firstN, flush, err)
+					continue
+				}
+				r.Close()
+
+				if !bytes.Equal(got, want) {
+					t.Errorf("i=%d, firstN=%d, flush=%t: corruption during deflate-then-inflate", i, firstN, flush)
+					continue
+				}
+			}
+		}
+	}
+}
diff --git a/libgo/go/compress/flate/deflatefast.go b/libgo/go/compress/flate/deflatefast.go
new file mode 100644
index 00000000000..6b881a477c4
--- /dev/null
+++ b/libgo/go/compress/flate/deflatefast.go
@@ -0,0 +1,174 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// This encoding algorithm, which prioritizes speed over output size, is
+// based on Snappy's LZ77-style encoder: github.com/golang/snappy
+
+const (
+	tableBits  = 14             // Bits used in the table.
+	tableSize  = 1 << tableBits // Size of the table.
+	tableMask  = tableSize - 1  // Mask for table indices. Redundant, but can eliminate bounds checks.
+	tableShift = 32 - tableBits // Right-shift to get the tableBits most significant bits of a uint32.
+)
+
+func load32(b []byte, i int) uint32 {
+	b = b[i : i+4 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func load64(b []byte, i int) uint64 {
+	b = b[i : i+8 : len(b)] // Help the compiler eliminate bounds checks on the next line.
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func hash(u uint32) uint32 {
+	return (u * 0x1e35a7bd) >> tableShift
+}
+
+// These constants are defined by the Snappy implementation so that its
+// assembly implementation can fast-path some 16-bytes-at-a-time copies. They
+// aren't necessary in the pure Go implementation, as we don't use those same
+// optimizations, but using the same thresholds doesn't really hurt.
+const (
+	inputMargin            = 16 - 1
+	minNonLiteralBlockSize = 1 + 1 + inputMargin
+)
+
+func encodeBestSpeed(dst []token, src []byte) []token {
+	// This check isn't in the Snappy implementation, but there, the caller
+	// instead of the callee handles this case.
+	if len(src) < minNonLiteralBlockSize {
+		return emitLiteral(dst, src)
+	}
+
+	// Initialize the hash table.
+	//
+	// The table element type is uint16, as s < sLimit and sLimit < len(src)
+	// and len(src) <= maxStoreBlockSize and maxStoreBlockSize == 65535.
+	var table [tableSize]uint16
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := len(src) - inputMargin
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	nextEmit := 0
+
+	// The encoded form must start with a literal, as there are no previous
+	// bytes to copy, so we start looking for hash matches at s == 1.
+	s := 1
+	nextHash := hash(load32(src, s))
+
+	for {
+		// Copied from the C++ snappy implementation:
+		//
+		// Heuristic match skipping: If 32 bytes are scanned with no matches
+		// found, start looking only at every other byte. If 32 more bytes are
+		// scanned (or skipped), look at every third byte, etc.. When a match
+		// is found, immediately go back to looking at every byte. This is a
+		// small loss (~5% performance, ~0.1% density) for compressible data
+		// due to more bookkeeping, but for non-compressible data (such as
+		// JPEG) it's a huge win since the compressor quickly "realizes" the
+		// data is incompressible and doesn't bother looking for matches
+		// everywhere.
+		//
+		// The "skip" variable keeps track of how many bytes there are since
+		// the last match; dividing it by 32 (ie. right-shifting by five) gives
+		// the number of bytes to move ahead for each iteration.
+		skip := 32
+
+		nextS := s
+		candidate := 0
+		for {
+			s = nextS
+			bytesBetweenHashLookups := skip >> 5
+			nextS = s + bytesBetweenHashLookups
+			skip += bytesBetweenHashLookups
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			candidate = int(table[nextHash&tableMask])
+			table[nextHash&tableMask] = uint16(s)
+			nextHash = hash(load32(src, nextS))
+			// TODO: < should be <=, and add a test for that.
+			if s-candidate < maxMatchOffset && load32(src, s) == load32(src, candidate) {
+				break
+			}
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+		dst = emitLiteral(dst, src[nextEmit:s])
+
+		// Call emitCopy, and then see if another emitCopy could be our next
+		// move. Repeat until we find no match for the input immediately after
+		// what was consumed by the last emitCopy call.
+		//
+		// If we exit this loop normally then we need to call emitLiteral next,
+		// though we don't yet know how big the literal will be. We handle that
+		// by proceeding to the next iteration of the main loop. We also can
+		// exit this loop via goto if we get close to exhausting the input.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+			base := s
+
+			// Extend the 4-byte match as long as possible.
+			//
+			// This is an inlined version of Snappy's:
+			//	s = extendMatch(src, candidate+4, s+4)
+			s += 4
+			s1 := base + maxMatchLength
+			if s1 > len(src) {
+				s1 = len(src)
+			}
+			for i := candidate + 4; s < s1 && src[i] == src[s]; i, s = i+1, s+1 {
+			}
+
+			// matchToken is flate's equivalent of Snappy's emitCopy.
+			dst = append(dst, matchToken(uint32(s-base-baseMatchLength), uint32(base-candidate-baseMatchOffset)))
+			nextEmit = s
+			if s >= sLimit {
+				goto emitRemainder
+			}
+
+			// We could immediately start working at s now, but to improve
+			// compression we first update the hash table at s-1 and at s. If
+			// another emitCopy is not our next move, also calculate nextHash
+			// at s+1. At least on GOARCH=amd64, these three hash calculations
+			// are faster as one load64 call (with some shifts) instead of
+			// three load32 calls.
+			x := load64(src, s-1)
+			prevHash := hash(uint32(x >> 0))
+			table[prevHash&tableMask] = uint16(s - 1)
+			currHash := hash(uint32(x >> 8))
+			candidate = int(table[currHash&tableMask])
+			table[currHash&tableMask] = uint16(s)
+			// TODO: >= should be >, and add a test for that.
+			if s-candidate >= maxMatchOffset || uint32(x>>8) != load32(src, candidate) {
+				nextHash = hash(uint32(x >> 16))
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if nextEmit < len(src) {
+		dst = emitLiteral(dst, src[nextEmit:])
+	}
+	return dst
+}
+
+func emitLiteral(dst []token, lit []byte) []token {
+	for _, v := range lit {
+		dst = append(dst, token(v))
+	}
+	return dst
+}
diff --git a/libgo/go/compress/flate/dict_decoder.go b/libgo/go/compress/flate/dict_decoder.go
new file mode 100644
index 00000000000..71c75a065ea
--- /dev/null
+++ b/libgo/go/compress/flate/dict_decoder.go
@@ -0,0 +1,184 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+// dictDecoder implements the LZ77 sliding dictionary as used in decompression.
+// LZ77 decompresses data through sequences of two forms of commands:
+//
+//	* Literal insertions: Runs of one or more symbols are inserted into the data
+//	stream as is. This is accomplished through the writeByte method for a
+//	single symbol, or combinations of writeSlice/writeMark for multiple symbols.
+//	Any valid stream must start with a literal insertion if no preset dictionary
+//	is used.
+//
+//	* Backward copies: Runs of one or more symbols are copied from previously
+//	emitted data. Backward copies come as the tuple (dist, length) where dist
+//	determines how far back in the stream to copy from and length determines how
+//	many bytes to copy. Note that it is valid for the length to be greater than
+//	the distance. Since LZ77 uses forward copies, that situation is used to
+//	perform a form of run-length encoding on repeated runs of symbols.
+//	The writeCopy and tryWriteCopy are used to implement this command.
+//
+// For performance reasons, this implementation performs little to no sanity
+// checks about the arguments. As such, the invariants documented for each
+// method call must be respected.
+type dictDecoder struct {
+	hist []byte // Sliding window history
+
+	// Invariant: 0 <= rdPos <= wrPos <= len(hist)
+	wrPos int  // Current output position in buffer
+	rdPos int  // Have emitted hist[:rdPos] already
+	full  bool // Has a full window length been written yet?
+}
+
+// init initializes dictDecoder to have a sliding window dictionary of the given
+// size. If a preset dict is provided, it will initialize the dictionary with
+// the contents of dict.
+func (dd *dictDecoder) init(size int, dict []byte) {
+	*dd = dictDecoder{hist: dd.hist}
+
+	if cap(dd.hist) < size {
+		dd.hist = make([]byte, size)
+	}
+	dd.hist = dd.hist[:size]
+
+	if len(dict) > len(dd.hist) {
+		dict = dict[len(dict)-len(dd.hist):]
+	}
+	dd.wrPos = copy(dd.hist, dict)
+	if dd.wrPos == len(dd.hist) {
+		dd.wrPos = 0
+		dd.full = true
+	}
+	dd.rdPos = dd.wrPos
+}
+
+// histSize reports the total amount of historical data in the dictionary.
+func (dd *dictDecoder) histSize() int {
+	if dd.full {
+		return len(dd.hist)
+	}
+	return dd.wrPos
+}
+
+// availRead reports the number of bytes that can be flushed by readFlush.
+func (dd *dictDecoder) availRead() int {
+	return dd.wrPos - dd.rdPos
+}
+
+// availWrite reports the available amount of output buffer space.
+func (dd *dictDecoder) availWrite() int {
+	return len(dd.hist) - dd.wrPos
+}
+
+// writeSlice returns a slice of the available buffer to write data to.
+//
+// This invariant will be kept: len(s) <= availWrite()
+func (dd *dictDecoder) writeSlice() []byte {
+	return dd.hist[dd.wrPos:]
+}
+
+// writeMark advances the writer pointer by cnt.
+//
+// This invariant must be kept: 0 <= cnt <= availWrite()
+func (dd *dictDecoder) writeMark(cnt int) {
+	dd.wrPos += cnt
+}
+
+// writeByte writes a single byte to the dictionary.
+//
+// This invariant must be kept: 0 < availWrite()
+func (dd *dictDecoder) writeByte(c byte) {
+	dd.hist[dd.wrPos] = c
+	dd.wrPos++
+}
+
+// writeCopy copies a string at a given (dist, length) to the output.
+// This returns the number of bytes copied and may be less than the requested
+// length if the available space in the output buffer is too small.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) writeCopy(dist, length int) int {
+	dstBase := dd.wrPos
+	dstPos := dstBase
+	srcPos := dstPos - dist
+	endPos := dstPos + length
+	if endPos > len(dd.hist) {
+		endPos = len(dd.hist)
+	}
+
+	// Copy non-overlapping section after destination position.
+	//
+	// This section is non-overlapping in that the copy length for this section
+	// is always less than or equal to the backwards distance. This can occur
+	// if a distance refers to data that wraps-around in the buffer.
+	// Thus, a backwards copy is performed here; that is, the exact bytes in
+	// the source prior to the copy is placed in the destination.
+	if srcPos < 0 {
+		srcPos += len(dd.hist)
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:])
+		srcPos = 0
+	}
+
+	// Copy possibly overlapping section before destination position.
+	//
+	// This section can overlap if the copy length for this section is larger
+	// than the backwards distance. This is allowed by LZ77 so that repeated
+	// strings can be succinctly represented using (dist, length) pairs.
+	// Thus, a forwards copy is performed here; that is, the bytes copied is
+	// possibly dependent on the resulting bytes in the destination as the copy
+	// progresses along. This is functionally equivalent to the following:
+	//
+	//	for i := 0; i < endPos-dstPos; i++ {
+	//		dd.hist[dstPos+i] = dd.hist[srcPos+i]
+	//	}
+	//	dstPos = endPos
+	//
+	for dstPos < endPos {
+		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+	}
+
+	dd.wrPos = dstPos
+	return dstPos - dstBase
+}
+
+// tryWriteCopy tries to copy a string at a given (distance, length) to the
+// output. This specialized version is optimized for short distances.
+//
+// This method is designed to be inlined for performance reasons.
+//
+// This invariant must be kept: 0 < dist <= histSize()
+func (dd *dictDecoder) tryWriteCopy(dist, length int) int {
+	dstPos := dd.wrPos
+	endPos := dstPos + length
+	if dstPos < dist || endPos > len(dd.hist) {
+		return 0
+	}
+	dstBase := dstPos
+	srcPos := dstPos - dist
+
+	// Copy possibly overlapping section before destination position.
+loop:
+	dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
+	if dstPos < endPos {
+		goto loop // Avoid for-loop so that this function can be inlined
+	}
+
+	dd.wrPos = dstPos
+	return dstPos - dstBase
+}
+
+// readFlush returns a slice of the historical buffer that is ready to be
+// emitted to the user. The data returned by readFlush must be fully consumed
+// before calling any other dictDecoder methods.
+func (dd *dictDecoder) readFlush() []byte {
+	toRead := dd.hist[dd.rdPos:dd.wrPos]
+	dd.rdPos = dd.wrPos
+	if dd.wrPos == len(dd.hist) {
+		dd.wrPos, dd.rdPos = 0, 0
+		dd.full = true
+	}
+	return toRead
+}
diff --git a/libgo/go/compress/flate/dict_decoder_test.go b/libgo/go/compress/flate/dict_decoder_test.go
new file mode 100644
index 00000000000..9275cff7911
--- /dev/null
+++ b/libgo/go/compress/flate/dict_decoder_test.go
@@ -0,0 +1,139 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestDictDecoder(t *testing.T) {
+	const (
+		abc  = "ABC\n"
+		fox  = "The quick brown fox jumped over the lazy dog!\n"
+		poem = "The Road Not Taken\nRobert Frost\n" +
+			"\n" +
+			"Two roads diverged in a yellow wood,\n" +
+			"And sorry I could not travel both\n" +
+			"And be one traveler, long I stood\n" +
+			"And looked down one as far as I could\n" +
+			"To where it bent in the undergrowth;\n" +
+			"\n" +
+			"Then took the other, as just as fair,\n" +
+			"And having perhaps the better claim,\n" +
+			"Because it was grassy and wanted wear;\n" +
+			"Though as for that the passing there\n" +
+			"Had worn them really about the same,\n" +
+			"\n" +
+			"And both that morning equally lay\n" +
+			"In leaves no step had trodden black.\n" +
+			"Oh, I kept the first for another day!\n" +
+			"Yet knowing how way leads on to way,\n" +
+			"I doubted if I should ever come back.\n" +
+			"\n" +
+			"I shall be telling this with a sigh\n" +
+			"Somewhere ages and ages hence:\n" +
+			"Two roads diverged in a wood, and I-\n" +
+			"I took the one less traveled by,\n" +
+			"And that has made all the difference.\n"
+	)
+
+	var poemRefs = []struct {
+		dist   int // Backward distance (0 if this is an insertion)
+		length int // Length of copy or insertion
+	}{
+		{0, 38}, {33, 3}, {0, 48}, {79, 3}, {0, 11}, {34, 5}, {0, 6}, {23, 7},
+		{0, 8}, {50, 3}, {0, 2}, {69, 3}, {34, 5}, {0, 4}, {97, 3}, {0, 4},
+		{43, 5}, {0, 6}, {7, 4}, {88, 7}, {0, 12}, {80, 3}, {0, 2}, {141, 4},
+		{0, 1}, {196, 3}, {0, 3}, {157, 3}, {0, 6}, {181, 3}, {0, 2}, {23, 3},
+		{77, 3}, {28, 5}, {128, 3}, {110, 4}, {70, 3}, {0, 4}, {85, 6}, {0, 2},
+		{182, 6}, {0, 4}, {133, 3}, {0, 7}, {47, 5}, {0, 20}, {112, 5}, {0, 1},
+		{58, 3}, {0, 8}, {59, 3}, {0, 4}, {173, 3}, {0, 5}, {114, 3}, {0, 4},
+		{92, 5}, {0, 2}, {71, 3}, {0, 2}, {76, 5}, {0, 1}, {46, 3}, {96, 4},
+		{130, 4}, {0, 3}, {360, 3}, {0, 3}, {178, 5}, {0, 7}, {75, 3}, {0, 3},
+		{45, 6}, {0, 6}, {299, 6}, {180, 3}, {70, 6}, {0, 1}, {48, 3}, {66, 4},
+		{0, 3}, {47, 5}, {0, 9}, {325, 3}, {0, 1}, {359, 3}, {318, 3}, {0, 2},
+		{199, 3}, {0, 1}, {344, 3}, {0, 3}, {248, 3}, {0, 10}, {310, 3}, {0, 3},
+		{93, 6}, {0, 3}, {252, 3}, {157, 4}, {0, 2}, {273, 5}, {0, 14}, {99, 4},
+		{0, 1}, {464, 4}, {0, 2}, {92, 4}, {495, 3}, {0, 1}, {322, 4}, {16, 4},
+		{0, 3}, {402, 3}, {0, 2}, {237, 4}, {0, 2}, {432, 4}, {0, 1}, {483, 5},
+		{0, 2}, {294, 4}, {0, 2}, {306, 3}, {113, 5}, {0, 1}, {26, 4}, {164, 3},
+		{488, 4}, {0, 1}, {542, 3}, {248, 6}, {0, 5}, {205, 3}, {0, 8}, {48, 3},
+		{449, 6}, {0, 2}, {192, 3}, {328, 4}, {9, 5}, {433, 3}, {0, 3}, {622, 25},
+		{615, 5}, {46, 5}, {0, 2}, {104, 3}, {475, 10}, {549, 3}, {0, 4}, {597, 8},
+		{314, 3}, {0, 1}, {473, 6}, {317, 5}, {0, 1}, {400, 3}, {0, 3}, {109, 3},
+		{151, 3}, {48, 4}, {0, 4}, {125, 3}, {108, 3}, {0, 2},
+	}
+
+	var got, want bytes.Buffer
+	var dd dictDecoder
+	dd.init(1<<11, nil)
+
+	var writeCopy = func(dist, length int) {
+		for length > 0 {
+			cnt := dd.tryWriteCopy(dist, length)
+			if cnt == 0 {
+				cnt = dd.writeCopy(dist, length)
+			}
+
+			length -= cnt
+			if dd.availWrite() == 0 {
+				got.Write(dd.readFlush())
+			}
+		}
+	}
+	var writeString = func(str string) {
+		for len(str) > 0 {
+			cnt := copy(dd.writeSlice(), str)
+			str = str[cnt:]
+			dd.writeMark(cnt)
+			if dd.availWrite() == 0 {
+				got.Write(dd.readFlush())
+			}
+		}
+	}
+
+	writeString(".")
+	want.WriteByte('.')
+
+	str := poem
+	for _, ref := range poemRefs {
+		if ref.dist == 0 {
+			writeString(str[:ref.length])
+		} else {
+			writeCopy(ref.dist, ref.length)
+		}
+		str = str[ref.length:]
+	}
+	want.WriteString(poem)
+
+	writeCopy(dd.histSize(), 33)
+	want.Write(want.Bytes()[:33])
+
+	writeString(abc)
+	writeCopy(len(abc), 59*len(abc))
+	want.WriteString(strings.Repeat(abc, 60))
+
+	writeString(fox)
+	writeCopy(len(fox), 9*len(fox))
+	want.WriteString(strings.Repeat(fox, 10))
+
+	writeString(".")
+	writeCopy(1, 9)
+	want.WriteString(strings.Repeat(".", 10))
+
+	writeString(strings.ToUpper(poem))
+	writeCopy(len(poem), 7*len(poem))
+	want.WriteString(strings.Repeat(strings.ToUpper(poem), 8))
+
+	writeCopy(dd.histSize(), 10)
+	want.Write(want.Bytes()[want.Len()-dd.histSize():][:10])
+
+	got.Write(dd.readFlush())
+	if got.String() != want.String() {
+		t.Errorf("final string mismatch:\ngot  %q\nwant %q", got.String(), want.String())
+	}
+}
diff --git a/libgo/go/compress/flate/flate_test.go b/libgo/go/compress/flate/flate_test.go
index 341d8071313..83c20498cc4 100644
--- a/libgo/go/compress/flate/flate_test.go
+++ b/libgo/go/compress/flate/flate_test.go
@@ -272,3 +272,81 @@ func TestTruncatedStreams(t *testing.T) {
 		}
 	}
 }
+
+// Verify that flate.Reader.Read returns (n, io.EOF) instead
+// of (n, nil) + (0, io.EOF) when possible.
+//
+// This helps net/http.Transport reuse HTTP/1 connections more
+// aggressively.
+//
+// See https://github.com/google/go-github/pull/317 for background.
+func TestReaderEarlyEOF(t *testing.T) {
+	testSizes := []int{
+		1, 2, 3, 4, 5, 6, 7, 8,
+		100, 1000, 10000, 100000,
+		128, 1024, 16384, 131072,
+
+		// Testing multiples of windowSize triggers the case
+		// where Read will fail to return an early io.EOF.
+		windowSize * 1, windowSize * 2, windowSize * 3,
+	}
+
+	var maxSize int
+	for _, n := range testSizes {
+		if maxSize < n {
+			maxSize = n
+		}
+	}
+
+	readBuf := make([]byte, 40)
+	data := make([]byte, maxSize)
+	for i := range data {
+		data[i] = byte(i)
+	}
+
+	for _, sz := range testSizes {
+		if testing.Short() && sz > windowSize {
+			continue
+		}
+		for _, flush := range []bool{true, false} {
+			earlyEOF := true // Do we expect early io.EOF?
+
+			var buf bytes.Buffer
+			w, _ := NewWriter(&buf, 5)
+			w.Write(data[:sz])
+			if flush {
+				// If a Flush occurs after all the actual data, the flushing
+				// semantics dictate that we will observe a (0, io.EOF) since
+				// Read must return data before it knows that the stream ended.
+				w.Flush()
+				earlyEOF = false
+			}
+			w.Close()
+
+			r := NewReader(&buf)
+			for {
+				n, err := r.Read(readBuf)
+				if err == io.EOF {
+					// If the availWrite == windowSize, then that means that the
+					// previous Read returned because the write buffer was full
+					// and it just so happened that the stream had no more data.
+					// This situation is rare, but unavoidable.
+					if r.(*decompressor).dict.availWrite() == windowSize {
+						earlyEOF = false
+					}
+
+					if n == 0 && earlyEOF {
+						t.Errorf("On size:%d flush:%v, Read() = (0, io.EOF), want (n, io.EOF)", sz, flush)
+					}
+					if n != 0 && !earlyEOF {
+						t.Errorf("On size:%d flush:%v, Read() = (%d, io.EOF), want (0, io.EOF)", sz, flush, n)
+					}
+					break
+				}
+				if err != nil {
+					t.Fatal(err)
+				}
+			}
+		}
+	}
+}
diff --git a/libgo/go/compress/flate/huffman_bit_writer.go b/libgo/go/compress/flate/huffman_bit_writer.go
index 616440412e4..c4adef9ff53 100644
--- a/libgo/go/compress/flate/huffman_bit_writer.go
+++ b/libgo/go/compress/flate/huffman_bit_writer.go
@@ -6,7 +6,6 @@ package flate
 
 import (
 	"io"
-	"math"
 )
 
 const (
@@ -22,6 +21,17 @@ const (
 	// The number of codegen codes.
 	codegenCodeCount = 19
 	badCode          = 255
+
+	// bufferFlushSize indicates the buffer size
+	// after which bytes are flushed to the writer.
+	// Should preferably be a multiple of 6, since
+	// we accumulate 6 bytes between writes to the buffer.
+	bufferFlushSize = 240
+
+	// bufferSize is the actual output byte buffer size.
+	// It must have additional headroom for a flush
+	// which can contain up to 8 bytes.
+	bufferSize = bufferFlushSize + 8
 )
 
 // The number of extra bits needed by length code X - LENGTH_CODES_START.
@@ -70,14 +80,14 @@ type huffmanBitWriter struct {
 	w io.Writer
 	// Data waiting to be written is bytes[0:nbytes]
 	// and then the low nbits of bits.
-	bits            uint32
-	nbits           uint32
-	bytes           [64]byte
+	bits            uint64
+	nbits           uint
+	bytes           [bufferSize]byte
+	codegenFreq     [codegenCodeCount]int32
 	nbytes          int
 	literalFreq     []int32
 	offsetFreq      []int32
 	codegen         []uint8
-	codegenFreq     []int32
 	literalEncoding *huffmanEncoder
 	offsetEncoding  *huffmanEncoder
 	codegenEncoding *huffmanEncoder
@@ -90,54 +100,16 @@ func newHuffmanBitWriter(w io.Writer) *huffmanBitWriter {
 		literalFreq:     make([]int32, maxNumLit),
 		offsetFreq:      make([]int32, offsetCodeCount),
 		codegen:         make([]uint8, maxNumLit+offsetCodeCount+1),
-		codegenFreq:     make([]int32, codegenCodeCount),
 		literalEncoding: newHuffmanEncoder(maxNumLit),
-		offsetEncoding:  newHuffmanEncoder(offsetCodeCount),
 		codegenEncoding: newHuffmanEncoder(codegenCodeCount),
+		offsetEncoding:  newHuffmanEncoder(offsetCodeCount),
 	}
 }
 
 func (w *huffmanBitWriter) reset(writer io.Writer) {
 	w.w = writer
 	w.bits, w.nbits, w.nbytes, w.err = 0, 0, 0, nil
-	w.bytes = [64]byte{}
-	for i := range w.codegen {
-		w.codegen[i] = 0
-	}
-	for _, s := range [...][]int32{w.literalFreq, w.offsetFreq, w.codegenFreq} {
-		for i := range s {
-			s[i] = 0
-		}
-	}
-	for _, enc := range [...]*huffmanEncoder{
-		w.literalEncoding,
-		w.offsetEncoding,
-		w.codegenEncoding} {
-		for i := range enc.code {
-			enc.code[i] = 0
-		}
-		for i := range enc.codeBits {
-			enc.codeBits[i] = 0
-		}
-	}
-}
-
-func (w *huffmanBitWriter) flushBits() {
-	if w.err != nil {
-		w.nbits = 0
-		return
-	}
-	bits := w.bits
-	w.bits >>= 16
-	w.nbits -= 16
-	n := w.nbytes
-	w.bytes[n] = byte(bits)
-	w.bytes[n+1] = byte(bits >> 8)
-	if n += 2; n >= len(w.bytes) {
-		_, w.err = w.w.Write(w.bytes[0:])
-		n = 0
-	}
-	w.nbytes = n
+	w.bytes = [bufferSize]byte{}
 }
 
 func (w *huffmanBitWriter) flush() {
@@ -146,26 +118,42 @@ func (w *huffmanBitWriter) flush() {
 		return
 	}
 	n := w.nbytes
-	if w.nbits > 8 {
+	for w.nbits != 0 {
 		w.bytes[n] = byte(w.bits)
 		w.bits >>= 8
-		w.nbits -= 8
-		n++
-	}
-	if w.nbits > 0 {
-		w.bytes[n] = byte(w.bits)
-		w.nbits = 0
+		if w.nbits > 8 { // Avoid underflow
+			w.nbits -= 8
+		} else {
+			w.nbits = 0
+		}
 		n++
 	}
 	w.bits = 0
-	_, w.err = w.w.Write(w.bytes[0:n])
+	_, w.err = w.w.Write(w.bytes[:n])
 	w.nbytes = 0
 }
 
-func (w *huffmanBitWriter) writeBits(b, nb int32) {
-	w.bits |= uint32(b) << w.nbits
-	if w.nbits += uint32(nb); w.nbits >= 16 {
-		w.flushBits()
+func (w *huffmanBitWriter) writeBits(b int32, nb uint) {
+	w.bits |= uint64(b) << w.nbits
+	w.nbits += nb
+	if w.nbits >= 48 {
+		bits := w.bits
+		w.bits >>= 48
+		w.nbits -= 48
+		n := w.nbytes
+		bytes := w.bytes[n : n+6]
+		bytes[0] = byte(bits)
+		bytes[1] = byte(bits >> 8)
+		bytes[2] = byte(bits >> 16)
+		bytes[3] = byte(bits >> 24)
+		bytes[4] = byte(bits >> 32)
+		bytes[5] = byte(bits >> 40)
+		n += 6
+		if n >= bufferFlushSize {
+			_, w.err = w.w.Write(w.bytes[:n])
+			n = 0
+		}
+		w.nbytes = n
 	}
 }
 
@@ -174,17 +162,18 @@ func (w *huffmanBitWriter) writeBytes(bytes []byte) {
 		return
 	}
 	n := w.nbytes
-	if w.nbits == 8 {
-		w.bytes[n] = byte(w.bits)
-		w.nbits = 0
-		n++
-	}
-	if w.nbits != 0 {
+	if w.nbits&7 != 0 {
 		w.err = InternalError("writeBytes with unfinished bits")
 		return
 	}
+	for w.nbits != 0 {
+		w.bytes[n] = byte(w.bits)
+		w.bits >>= 8
+		w.nbits -= 8
+		n++
+	}
 	if n != 0 {
-		_, w.err = w.w.Write(w.bytes[0:n])
+		_, w.err = w.w.Write(w.bytes[:n])
 		if w.err != nil {
 			return
 		}
@@ -200,11 +189,12 @@ func (w *huffmanBitWriter) writeBytes(bytes []byte) {
 // The result is written into the codegen array, and the frequencies
 // of each code is written into the codegenFreq array.
 // Codes 0-15 are single byte codes. Codes 16-18 are followed by additional
-// information.  Code badCode is an end marker
+// information. Code badCode is an end marker
 //
 //  numLiterals      The number of literals in literalEncoding
 //  numOffsets       The number of offsets in offsetEncoding
-func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int) {
+//  litenc, offenc   The literal and offset encoder to use
+func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int, litEnc, offEnc *huffmanEncoder) {
 	for i := range w.codegenFreq {
 		w.codegenFreq[i] = 0
 	}
@@ -213,9 +203,16 @@ func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int) {
 	// This is fine because the output is always shorter than the input used
 	// so far.
 	codegen := w.codegen // cache
-	// Copy the concatenated code sizes to codegen.  Put a marker at the end.
-	copy(codegen[0:numLiterals], w.literalEncoding.codeBits)
-	copy(codegen[numLiterals:numLiterals+numOffsets], w.offsetEncoding.codeBits)
+	// Copy the concatenated code sizes to codegen. Put a marker at the end.
+	cgnl := codegen[:numLiterals]
+	for i := range cgnl {
+		cgnl[i] = uint8(litEnc.codes[i].len)
+	}
+
+	cgnl = codegen[numLiterals : numLiterals+numOffsets]
+	for i := range cgnl {
+		cgnl[i] = uint8(offEnc.codes[i].len)
+	}
 	codegen[numLiterals+numOffsets] = badCode
 
 	size := codegen[0]
@@ -284,11 +281,71 @@ func (w *huffmanBitWriter) generateCodegen(numLiterals int, numOffsets int) {
 	codegen[outIndex] = badCode
 }
 
-func (w *huffmanBitWriter) writeCode(code *huffmanEncoder, literal uint32) {
+// dynamicSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) dynamicSize(litEnc, offEnc *huffmanEncoder, extraBits int) (size, numCodegens int) {
+	numCodegens = len(w.codegenFreq)
+	for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
+		numCodegens--
+	}
+	header := 3 + 5 + 5 + 4 + (3 * numCodegens) +
+		w.codegenEncoding.bitLength(w.codegenFreq[:]) +
+		int(w.codegenFreq[16])*2 +
+		int(w.codegenFreq[17])*3 +
+		int(w.codegenFreq[18])*7
+	size = header +
+		litEnc.bitLength(w.literalFreq) +
+		offEnc.bitLength(w.offsetFreq) +
+		extraBits
+
+	return size, numCodegens
+}
+
+// fixedSize returns the size of dynamically encoded data in bits.
+func (w *huffmanBitWriter) fixedSize(extraBits int) int {
+	return 3 +
+		fixedLiteralEncoding.bitLength(w.literalFreq) +
+		fixedOffsetEncoding.bitLength(w.offsetFreq) +
+		extraBits
+}
+
+// storedSize calculates the stored size, including header.
+// The function returns the size in bits and whether the block
+// fits inside a single block.
+func (w *huffmanBitWriter) storedSize(in []byte) (int, bool) {
+	if in == nil {
+		return 0, false
+	}
+	if len(in) <= maxStoreBlockSize {
+		return (len(in) + 5) * 8, true
+	}
+	return 0, false
+}
+
+func (w *huffmanBitWriter) writeCode(c hcode) {
 	if w.err != nil {
 		return
 	}
-	w.writeBits(int32(code.code[literal]), int32(code.codeBits[literal]))
+	w.bits |= uint64(c.code) << w.nbits
+	w.nbits += uint(c.len)
+	if w.nbits >= 48 {
+		bits := w.bits
+		w.bits >>= 48
+		w.nbits -= 48
+		n := w.nbytes
+		bytes := w.bytes[n : n+6]
+		bytes[0] = byte(bits)
+		bytes[1] = byte(bits >> 8)
+		bytes[2] = byte(bits >> 16)
+		bytes[3] = byte(bits >> 24)
+		bytes[4] = byte(bits >> 32)
+		bytes[5] = byte(bits >> 40)
+		n += 6
+		if n >= bufferFlushSize {
+			_, w.err = w.w.Write(w.bytes[:n])
+			n = 0
+		}
+		w.nbytes = n
+	}
 }
 
 // Write the header of a dynamic Huffman block to the output stream.
@@ -310,7 +367,7 @@ func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, n
 	w.writeBits(int32(numCodegens-4), 4)
 
 	for i := 0; i < numCodegens; i++ {
-		value := w.codegenEncoding.codeBits[codegenOrder[i]]
+		value := uint(w.codegenEncoding.codes[codegenOrder[i]].len)
 		w.writeBits(int32(value), 3)
 	}
 
@@ -321,8 +378,7 @@ func (w *huffmanBitWriter) writeDynamicHeader(numLiterals int, numOffsets int, n
 		if codeWord == badCode {
 			break
 		}
-		// The low byte contains the actual code to generate.
-		w.writeCode(w.codegenEncoding, uint32(codeWord))
+		w.writeCode(w.codegenEncoding.codes[uint32(codeWord)])
 
 		switch codeWord {
 		case 16:
@@ -367,10 +423,113 @@ func (w *huffmanBitWriter) writeFixedHeader(isEof bool) {
 	w.writeBits(value, 3)
 }
 
+// writeBlock will write a block of tokens with the smallest encoding.
+// The original input can be supplied, and if the huffman encoded data
+// is larger than the original bytes, the data will be written as a
+// stored block.
+// If the input is nil, the tokens will always be Huffman encoded.
 func (w *huffmanBitWriter) writeBlock(tokens []token, eof bool, input []byte) {
 	if w.err != nil {
 		return
 	}
+
+	tokens = append(tokens, endBlockMarker)
+	numLiterals, numOffsets := w.indexTokens(tokens)
+
+	var extraBits int
+	storedSize, storable := w.storedSize(input)
+	if storable {
+		// We only bother calculating the costs of the extra bits required by
+		// the length of offset fields (which will be the same for both fixed
+		// and dynamic encoding), if we need to compare those two encodings
+		// against stored encoding.
+		for lengthCode := lengthCodesStart + 8; lengthCode < numLiterals; lengthCode++ {
+			// First eight length codes have extra size = 0.
+			extraBits += int(w.literalFreq[lengthCode]) * int(lengthExtraBits[lengthCode-lengthCodesStart])
+		}
+		for offsetCode := 4; offsetCode < numOffsets; offsetCode++ {
+			// First four offset codes have extra size = 0.
+			extraBits += int(w.offsetFreq[offsetCode]) * int(offsetExtraBits[offsetCode])
+		}
+	}
+
+	// Figure out smallest code.
+	// Fixed Huffman baseline.
+	var literalEncoding = fixedLiteralEncoding
+	var offsetEncoding = fixedOffsetEncoding
+	var size = w.fixedSize(extraBits)
+
+	// Dynamic Huffman?
+	var numCodegens int
+
+	// Generate codegen and codegenFrequencies, which indicates how to encode
+	// the literalEncoding and the offsetEncoding.
+	w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
+	w.codegenEncoding.generate(w.codegenFreq[:], 7)
+	dynamicSize, numCodegens := w.dynamicSize(w.literalEncoding, w.offsetEncoding, extraBits)
+
+	if dynamicSize < size {
+		size = dynamicSize
+		literalEncoding = w.literalEncoding
+		offsetEncoding = w.offsetEncoding
+	}
+
+	// Stored bytes?
+	if storable && storedSize < size {
+		w.writeStoredHeader(len(input), eof)
+		w.writeBytes(input)
+		return
+	}
+
+	// Huffman.
+	if literalEncoding == fixedLiteralEncoding {
+		w.writeFixedHeader(eof)
+	} else {
+		w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+	}
+
+	// Write the tokens.
+	w.writeTokens(tokens, literalEncoding.codes, offsetEncoding.codes)
+}
+
+// writeBlockDynamic encodes a block using a dynamic Huffman table.
+// This should be used if the symbols used have a disproportionate
+// histogram distribution.
+// If input is supplied and the compression savings are below 1/16th of the
+// input size the block is stored.
+func (w *huffmanBitWriter) writeBlockDynamic(tokens []token, eof bool, input []byte) {
+	if w.err != nil {
+		return
+	}
+
+	tokens = append(tokens, endBlockMarker)
+	numLiterals, numOffsets := w.indexTokens(tokens)
+
+	// Generate codegen and codegenFrequencies, which indicates how to encode
+	// the literalEncoding and the offsetEncoding.
+	w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, w.offsetEncoding)
+	w.codegenEncoding.generate(w.codegenFreq[:], 7)
+	size, numCodegens := w.dynamicSize(w.literalEncoding, huffOffset, 0)
+
+	// Store bytes, if we don't get a reasonable improvement.
+	if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
+		w.writeStoredHeader(len(input), eof)
+		w.writeBytes(input)
+		return
+	}
+
+	// Write Huffman table.
+	w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+
+	// Write the tokens.
+	w.writeTokens(tokens, w.literalEncoding.codes, w.offsetEncoding.codes)
+}
+
+// indexTokens indexes a slice of tokens, and updates
+// literalFreq and offsetFreq, and generates literalEncoding
+// and offsetEncoding.
+// The number of literal and offset tokens is returned.
+func (w *huffmanBitWriter) indexTokens(tokens []token) (numLiterals, numOffsets int) {
 	for i := range w.literalFreq {
 		w.literalFreq[i] = 0
 	}
@@ -378,29 +537,24 @@ func (w *huffmanBitWriter) writeBlock(tokens []token, eof bool, input []byte) {
 		w.offsetFreq[i] = 0
 	}
 
-	n := len(tokens)
-	tokens = tokens[0 : n+1]
-	tokens[n] = endBlockMarker
-
 	for _, t := range tokens {
-		switch t.typ() {
-		case literalType:
+		if t < matchType {
 			w.literalFreq[t.literal()]++
-		case matchType:
-			length := t.length()
-			offset := t.offset()
-			w.literalFreq[lengthCodesStart+lengthCode(length)]++
-			w.offsetFreq[offsetCode(offset)]++
+			continue
 		}
+		length := t.length()
+		offset := t.offset()
+		w.literalFreq[lengthCodesStart+lengthCode(length)]++
+		w.offsetFreq[offsetCode(offset)]++
 	}
 
 	// get the number of literals
-	numLiterals := len(w.literalFreq)
+	numLiterals = len(w.literalFreq)
 	for w.literalFreq[numLiterals-1] == 0 {
 		numLiterals--
 	}
 	// get the number of offsets
-	numOffsets := len(w.offsetFreq)
+	numOffsets = len(w.offsetFreq)
 	for numOffsets > 0 && w.offsetFreq[numOffsets-1] == 0 {
 		numOffsets--
 	}
@@ -410,108 +564,134 @@ func (w *huffmanBitWriter) writeBlock(tokens []token, eof bool, input []byte) {
 		w.offsetFreq[0] = 1
 		numOffsets = 1
 	}
-
 	w.literalEncoding.generate(w.literalFreq, 15)
 	w.offsetEncoding.generate(w.offsetFreq, 15)
+	return
+}
 
-	storedBytes := 0
-	if input != nil {
-		storedBytes = len(input)
-	}
-	var extraBits int64
-	var storedSize int64 = math.MaxInt64
-	if storedBytes <= maxStoreBlockSize && input != nil {
-		storedSize = int64((storedBytes + 5) * 8)
-		// We only bother calculating the costs of the extra bits required by
-		// the length of offset fields (which will be the same for both fixed
-		// and dynamic encoding), if we need to compare those two encodings
-		// against stored encoding.
-		for lengthCode := lengthCodesStart + 8; lengthCode < numLiterals; lengthCode++ {
-			// First eight length codes have extra size = 0.
-			extraBits += int64(w.literalFreq[lengthCode]) * int64(lengthExtraBits[lengthCode-lengthCodesStart])
+// writeTokens writes a slice of tokens to the output.
+// codes for literal and offset encoding must be supplied.
+func (w *huffmanBitWriter) writeTokens(tokens []token, leCodes, oeCodes []hcode) {
+	for _, t := range tokens {
+		if t < matchType {
+			w.writeCode(leCodes[t.literal()])
+			continue
 		}
-		for offsetCode := 4; offsetCode < numOffsets; offsetCode++ {
-			// First four offset codes have extra size = 0.
-			extraBits += int64(w.offsetFreq[offsetCode]) * int64(offsetExtraBits[offsetCode])
+		// Write the length
+		length := t.length()
+		lengthCode := lengthCode(length)
+		w.writeCode(leCodes[lengthCode+lengthCodesStart])
+		extraLengthBits := uint(lengthExtraBits[lengthCode])
+		if extraLengthBits > 0 {
+			extraLength := int32(length - lengthBase[lengthCode])
+			w.writeBits(extraLength, extraLengthBits)
+		}
+		// Write the offset
+		offset := t.offset()
+		offsetCode := offsetCode(offset)
+		w.writeCode(oeCodes[offsetCode])
+		extraOffsetBits := uint(offsetExtraBits[offsetCode])
+		if extraOffsetBits > 0 {
+			extraOffset := int32(offset - offsetBase[offsetCode])
+			w.writeBits(extraOffset, extraOffsetBits)
 		}
 	}
+}
 
-	// Figure out smallest code.
-	// Fixed Huffman baseline.
-	var size = int64(3) +
-		fixedLiteralEncoding.bitLength(w.literalFreq) +
-		fixedOffsetEncoding.bitLength(w.offsetFreq) +
-		extraBits
-	var literalEncoding = fixedLiteralEncoding
-	var offsetEncoding = fixedOffsetEncoding
+// huffOffset is a static offset encoder used for huffman only encoding.
+// It can be reused since we will not be encoding offset values.
+var huffOffset *huffmanEncoder
 
-	// Dynamic Huffman?
-	var numCodegens int
+func init() {
+	w := newHuffmanBitWriter(nil)
+	w.offsetFreq[0] = 1
+	huffOffset = newHuffmanEncoder(offsetCodeCount)
+	huffOffset.generate(w.offsetFreq, 15)
+}
 
-	// Generate codegen and codegenFrequencies, which indicates how to encode
-	// the literalEncoding and the offsetEncoding.
-	w.generateCodegen(numLiterals, numOffsets)
-	w.codegenEncoding.generate(w.codegenFreq, 7)
-	numCodegens = len(w.codegenFreq)
-	for numCodegens > 4 && w.codegenFreq[codegenOrder[numCodegens-1]] == 0 {
-		numCodegens--
+// writeBlockHuff encodes a block of bytes as either
+// Huffman encoded literals or uncompressed bytes if the
+// results only gains very little from compression.
+func (w *huffmanBitWriter) writeBlockHuff(eof bool, input []byte) {
+	if w.err != nil {
+		return
 	}
-	dynamicHeader := int64(3+5+5+4+(3*numCodegens)) +
-		w.codegenEncoding.bitLength(w.codegenFreq) +
-		int64(extraBits) +
-		int64(w.codegenFreq[16]*2) +
-		int64(w.codegenFreq[17]*3) +
-		int64(w.codegenFreq[18]*7)
-	dynamicSize := dynamicHeader +
-		w.literalEncoding.bitLength(w.literalFreq) +
-		w.offsetEncoding.bitLength(w.offsetFreq)
 
-	if dynamicSize < size {
-		size = dynamicSize
-		literalEncoding = w.literalEncoding
-		offsetEncoding = w.offsetEncoding
+	// Clear histogram
+	for i := range w.literalFreq {
+		w.literalFreq[i] = 0
 	}
 
-	// Stored bytes?
-	if storedSize < size {
-		w.writeStoredHeader(storedBytes, eof)
-		w.writeBytes(input[0:storedBytes])
+	// Add everything as literals
+	histogram(input, w.literalFreq)
+
+	w.literalFreq[endBlockMarker] = 1
+
+	const numLiterals = endBlockMarker + 1
+	const numOffsets = 1
+
+	w.literalEncoding.generate(w.literalFreq, 15)
+
+	// Figure out smallest code.
+	// Always use dynamic Huffman or Store
+	var numCodegens int
+
+	// Generate codegen and codegenFrequencies, which indicates how to encode
+	// the literalEncoding and the offsetEncoding.
+	w.generateCodegen(numLiterals, numOffsets, w.literalEncoding, huffOffset)
+	w.codegenEncoding.generate(w.codegenFreq[:], 7)
+	size, numCodegens := w.dynamicSize(w.literalEncoding, huffOffset, 0)
+
+	// Store bytes, if we don't get a reasonable improvement.
+	if ssize, storable := w.storedSize(input); storable && ssize < (size+size>>4) {
+		w.writeStoredHeader(len(input), eof)
+		w.writeBytes(input)
 		return
 	}
 
 	// Huffman.
-	if literalEncoding == fixedLiteralEncoding {
-		w.writeFixedHeader(eof)
-	} else {
-		w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
-	}
-	for _, t := range tokens {
-		switch t.typ() {
-		case literalType:
-			w.writeCode(literalEncoding, t.literal())
-			break
-		case matchType:
-			// Write the length
-			length := t.length()
-			lengthCode := lengthCode(length)
-			w.writeCode(literalEncoding, lengthCode+lengthCodesStart)
-			extraLengthBits := int32(lengthExtraBits[lengthCode])
-			if extraLengthBits > 0 {
-				extraLength := int32(length - lengthBase[lengthCode])
-				w.writeBits(extraLength, extraLengthBits)
-			}
-			// Write the offset
-			offset := t.offset()
-			offsetCode := offsetCode(offset)
-			w.writeCode(offsetEncoding, offsetCode)
-			extraOffsetBits := int32(offsetExtraBits[offsetCode])
-			if extraOffsetBits > 0 {
-				extraOffset := int32(offset - offsetBase[offsetCode])
-				w.writeBits(extraOffset, extraOffsetBits)
-			}
-			break
-		default:
-			panic("unknown token type: " + string(t))
+	w.writeDynamicHeader(numLiterals, numOffsets, numCodegens, eof)
+	encoding := w.literalEncoding.codes[:257]
+	n := w.nbytes
+	for _, t := range input {
+		// Bitwriting inlined, ~30% speedup
+		c := encoding[t]
+		w.bits |= uint64(c.code) << w.nbits
+		w.nbits += uint(c.len)
+		if w.nbits < 48 {
+			continue
 		}
+		// Store 6 bytes
+		bits := w.bits
+		w.bits >>= 48
+		w.nbits -= 48
+		bytes := w.bytes[n : n+6]
+		bytes[0] = byte(bits)
+		bytes[1] = byte(bits >> 8)
+		bytes[2] = byte(bits >> 16)
+		bytes[3] = byte(bits >> 24)
+		bytes[4] = byte(bits >> 32)
+		bytes[5] = byte(bits >> 40)
+		n += 6
+		if n < bufferFlushSize {
+			continue
+		}
+		_, w.err = w.w.Write(w.bytes[:n])
+		if w.err != nil {
+			return
+		}
+		n = 0
+	}
+	w.nbytes = n
+	w.writeCode(encoding[endBlockMarker])
+}
+
+// histogram accumulates a histogram of b in h.
+//
+// len(h) must be >= 256, and h's elements must be all zeroes.
+func histogram(b []byte, h []int32) {
+	h = h[:256]
+	for _, t := range b {
+		h[t]++
 	}
 }
diff --git a/libgo/go/compress/flate/huffman_bit_writer_test.go b/libgo/go/compress/flate/huffman_bit_writer_test.go
new file mode 100644
index 00000000000..882d3abec18
--- /dev/null
+++ b/libgo/go/compress/flate/huffman_bit_writer_test.go
@@ -0,0 +1,366 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package flate
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+var update = flag.Bool("update", false, "update reference files")
+
+// TestBlockHuff tests huffman encoding against reference files
+// to detect possible regressions.
+// If encoding/bit allocation changes you can regenerate these files
+// by using the -update flag.
+func TestBlockHuff(t *testing.T) {
+	// determine input files
+	match, err := filepath.Glob("testdata/huffman-*.in")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, in := range match {
+		out := in // for files where input and output are identical
+		if strings.HasSuffix(in, ".in") {
+			out = in[:len(in)-len(".in")] + ".golden"
+		}
+		testBlockHuff(t, in, out)
+	}
+}
+
+func testBlockHuff(t *testing.T, in, out string) {
+	all, err := ioutil.ReadFile(in)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	var buf bytes.Buffer
+	bw := newHuffmanBitWriter(&buf)
+	bw.writeBlockHuff(false, all)
+	bw.flush()
+	got := buf.Bytes()
+
+	want, err := ioutil.ReadFile(out)
+	if err != nil && !*update {
+		t.Error(err)
+		return
+	}
+
+	t.Logf("Testing %q", in)
+	if !bytes.Equal(got, want) {
+		if *update {
+			if in != out {
+				t.Logf("Updating %q", out)
+				if err := ioutil.WriteFile(out, got, 0666); err != nil {
+					t.Error(err)
+				}
+				return
+			}
+			// in == out: don't accidentally destroy input
+			t.Errorf("WARNING: -update did not rewrite input file %s", in)
+		}
+
+		t.Errorf("%q != %q (see %q)", in, out, in+".got")
+		if err := ioutil.WriteFile(in+".got", got, 0666); err != nil {
+			t.Error(err)
+		}
+		return
+	}
+	t.Log("Output ok")
+
+	// Test if the writer produces the same output after reset.
+	buf.Reset()
+	bw.reset(&buf)
+	bw.writeBlockHuff(false, all)
+	bw.flush()
+	got = buf.Bytes()
+	if !bytes.Equal(got, want) {
+		t.Errorf("after reset %q != %q (see %q)", in, out, in+".reset.got")
+		if err := ioutil.WriteFile(in+".reset.got", got, 0666); err != nil {
+			t.Error(err)
+		}
+		return
+	}
+	t.Log("Reset ok")
+	testWriterEOF(t, "huff", huffTest{input: in}, true)
+}
+
+type huffTest struct {
+	tokens      []token
+	input       string // File name of input data matching the tokens.
+	want        string // File name of data with the expected output with input available.
+	wantNoInput string // File name of the expected output when no input is available.
+}
+
+const ml = 0x7fc00000 // Maximum length token. Used to reduce the size of writeBlockTests
+
+var writeBlockTests = []huffTest{
+	{
+		input:       "testdata/huffman-null-max.in",
+		want:        "testdata/huffman-null-max.%s.expect",
+		wantNoInput: "testdata/huffman-null-max.%s.expect-noinput",
+		tokens:      []token{0x0, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, 0x0, 0x0},
+	},
+	{
+		input:       "testdata/huffman-pi.in",
+		want:        "testdata/huffman-pi.%s.expect",
+		wantNoInput: "testdata/huffman-pi.%s.expect-noinput",
+		tokens:      []token{0x33, 0x2e, 0x31, 0x34, 0x31, 0x35, 0x39, 0x32, 0x36, 0x35, 0x33, 0x35, 0x38, 0x39, 0x37, 0x39, 0x33, 0x32, 0x33, 0x38, 0x34, 0x36, 0x32, 0x36, 0x34, 0x33, 0x33, 0x38, 0x33, 0x32, 0x37, 0x39, 0x35, 0x30, 0x32, 0x38, 0x38, 0x34, 0x31, 0x39, 0x37, 0x31, 0x36, 0x39, 0x33, 0x39, 0x39, 0x33, 0x37, 0x35, 0x31, 0x30, 0x35, 0x38, 0x32, 0x30, 0x39, 0x37, 0x34, 0x39, 0x34, 0x34, 0x35, 0x39, 0x32, 0x33, 0x30, 0x37, 0x38, 0x31, 0x36, 0x34, 0x30, 0x36, 0x32, 0x38, 0x36, 0x32, 0x30, 0x38, 0x39, 0x39, 0x38, 0x36, 0x32, 0x38, 0x30, 0x33, 0x34, 0x38, 0x32, 0x35, 0x33, 0x34, 0x32, 0x31, 0x31, 0x37, 0x30, 0x36, 0x37, 0x39, 0x38, 0x32, 0x31, 0x34, 0x38, 0x30, 0x38, 0x36, 0x35, 0x31, 0x33, 0x32, 0x38, 0x32, 0x33, 0x30, 0x36, 0x36, 0x34, 0x37, 0x30, 0x39, 0x33, 0x38, 0x34, 0x34, 0x36, 0x30, 0x39, 0x35, 0x35, 0x30, 0x35, 0x38, 0x32, 0x32, 0x33, 0x31, 0x37, 0x32, 0x35, 0x33, 0x35, 0x39, 0x34, 0x30, 0x38, 0x31, 0x32, 0x38, 0x34, 0x38, 0x31, 0x31, 0x31, 0x37, 0x34, 0x4040007e, 0x34, 0x31, 0x30, 0x32, 0x37, 0x30, 0x31, 0x39, 0x33, 0x38, 0x35, 0x32, 0x31, 0x31, 0x30, 0x35, 0x35, 0x35, 0x39, 0x36, 0x34, 0x34, 0x36, 0x32, 0x32, 0x39, 0x34, 0x38, 0x39, 0x35, 0x34, 0x39, 0x33, 0x30, 0x33, 0x38, 0x31, 0x40400012, 0x32, 0x38, 0x38, 0x31, 0x30, 0x39, 0x37, 0x35, 0x36, 0x36, 0x35, 0x39, 0x33, 0x33, 0x34, 0x34, 0x36, 0x40400047, 0x37, 0x35, 0x36, 0x34, 0x38, 0x32, 0x33, 0x33, 0x37, 0x38, 0x36, 0x37, 0x38, 0x33, 0x31, 0x36, 0x35, 0x32, 0x37, 0x31, 0x32, 0x30, 0x31, 0x39, 0x30, 0x39, 0x31, 0x34, 0x4040001a, 0x35, 0x36, 0x36, 0x39, 0x32, 0x33, 0x34, 0x36, 0x404000b2, 0x36, 0x31, 0x30, 0x34, 0x35, 0x34, 0x33, 0x32, 0x36, 0x40400032, 0x31, 0x33, 0x33, 0x39, 0x33, 0x36, 0x30, 0x37, 0x32, 0x36, 0x30, 0x32, 0x34, 0x39, 0x31, 0x34, 0x31, 0x32, 0x37, 0x33, 0x37, 0x32, 0x34, 0x35, 0x38, 0x37, 0x30, 0x30, 0x36, 0x36, 0x30, 0x36, 0x33, 0x31, 0x35, 0x35, 0x38, 0x38, 0x31, 0x37, 0x34, 0x38, 0x38, 0x31, 0x35, 0x32, 0x30, 0x39, 0x32, 0x30, 0x39, 0x36, 0x32, 0x38, 0x32, 0x39, 0x32, 0x35, 0x34, 0x30, 0x39, 0x31, 0x37, 0x31, 0x35, 0x33, 0x36, 0x34, 0x33, 0x36, 0x37, 0x38, 0x39, 0x32, 0x35, 0x39, 0x30, 0x33, 0x36, 0x30, 0x30, 0x31, 0x31, 0x33, 0x33, 0x30, 0x35, 0x33, 0x30, 0x35, 0x34, 0x38, 0x38, 0x32, 0x30, 0x34, 0x36, 0x36, 0x35, 0x32, 0x31, 0x33, 0x38, 0x34, 0x31, 0x34, 0x36, 0x39, 0x35, 0x31, 0x39, 0x34, 0x31, 0x35, 0x31, 0x31, 0x36, 0x30, 0x39, 0x34, 0x33, 0x33, 0x30, 0x35, 0x37, 0x32, 0x37, 0x30, 0x33, 0x36, 0x35, 0x37, 0x35, 0x39, 0x35, 0x39, 0x31, 0x39, 0x35, 0x33, 0x30, 0x39, 0x32, 0x31, 0x38, 0x36, 0x31, 0x31, 0x37, 0x404000e9, 0x33, 0x32, 0x40400009, 0x39, 0x33, 0x31, 0x30, 0x35, 0x31, 0x31, 0x38, 0x35, 0x34, 0x38, 0x30, 0x37, 0x4040010e, 0x33, 0x37, 0x39, 0x39, 0x36, 0x32, 0x37, 0x34, 0x39, 0x35, 0x36, 0x37, 0x33, 0x35, 0x31, 0x38, 0x38, 0x35, 0x37, 0x35, 0x32, 0x37, 0x32, 0x34, 0x38, 0x39, 0x31, 0x32, 0x32, 0x37, 0x39, 0x33, 0x38, 0x31, 0x38, 0x33, 0x30, 0x31, 0x31, 0x39, 0x34, 0x39, 0x31, 0x32, 0x39, 0x38, 0x33, 0x33, 0x36, 0x37, 0x33, 0x33, 0x36, 0x32, 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0x31, 0x40400be7, 0x31, 0x32, 0x40400c74, 0x30, 0x404003c3, 0x33, 0x39, 0x40400b2a, 0x40400112, 0x37, 0x31, 0x35, 0x404003b0, 0x34, 0x32, 0x30, 0x40800bf2, 0x39, 0x40400bc2, 0x30, 0x37, 0x40400341, 0x40400795, 0x40400aaf, 0x40400c62, 0x32, 0x31, 0x40400960, 0x32, 0x35, 0x31, 0x4040057b, 0x40400944, 0x39, 0x32, 0x404001b2, 0x38, 0x32, 0x36, 0x40400b66, 0x32, 0x40400278, 0x33, 0x32, 0x31, 0x35, 0x37, 0x39, 0x31, 0x39, 0x38, 0x34, 0x31, 0x34, 0x4080087b, 0x39, 0x31, 0x36, 0x34, 0x408006e8, 0x39, 0x40800b58, 0x404008db, 0x37, 0x32, 0x32, 0x40400321, 0x35, 0x404008a4, 0x40400141, 0x39, 0x31, 0x30, 0x404000bc, 0x40400c5b, 0x35, 0x32, 0x38, 0x30, 0x31, 0x37, 0x40400231, 0x37, 0x31, 0x32, 0x40400914, 0x38, 0x33, 0x32, 0x40400373, 0x31, 0x40400589, 0x30, 0x39, 0x33, 0x35, 0x33, 0x39, 0x36, 0x35, 0x37, 0x4040064b, 0x31, 0x30, 0x38, 0x33, 0x40400069, 0x35, 0x31, 0x4040077a, 0x40400d5a, 0x31, 0x34, 0x34, 0x34, 0x32, 0x31, 0x30, 0x30, 0x40400202, 0x30, 0x33, 0x4040019c, 0x31, 0x31, 0x30, 0x33, 0x40400c81, 0x40400009, 0x40400026, 0x40c00602, 0x35, 0x31, 0x36, 0x404005d9, 0x40800883, 0x4040092a, 0x35, 0x40800c42, 0x38, 0x35, 0x31, 0x37, 0x31, 0x34, 0x33, 0x37, 0x40400605, 0x4040006d, 0x31, 0x35, 0x35, 0x36, 0x35, 0x30, 0x38, 0x38, 0x404003b9, 0x39, 0x38, 0x39, 0x38, 0x35, 0x39, 0x39, 0x38, 0x32, 0x33, 0x38, 0x404001cf, 0x404009ba, 0x33, 0x4040016c, 0x4040043e, 0x404009c3, 0x38, 0x40800e05, 0x33, 0x32, 0x40400107, 0x35, 0x40400305, 0x33, 0x404001ca, 0x39, 0x4040041b, 0x39, 0x38, 0x4040087d, 0x34, 0x40400cb8, 0x37, 0x4040064b, 0x30, 0x37, 0x404000e5, 0x34, 0x38, 0x31, 0x34, 0x31, 0x40400539, 0x38, 0x35, 0x39, 0x34, 0x36, 0x31, 0x40400bc9, 0x38, 0x30},
+	},
+	{
+		input:       "testdata/huffman-rand-1k.in",
+		want:        "testdata/huffman-rand-1k.%s.expect",
+		wantNoInput: "testdata/huffman-rand-1k.%s.expect-noinput",
+		tokens:      []token{0xf8, 0x8b, 0x96, 0x76, 0x48, 0xd, 0x85, 0x94, 0x25, 0x80, 0xaf, 0xc2, 0xfe, 0x8d, 0xe8, 0x20, 0xeb, 0x17, 0x86, 0xc9, 0xb7, 0xc5, 0xde, 0x6, 0xea, 0x7d, 0x18, 0x8b, 0xe7, 0x3e, 0x7, 0xda, 0xdf, 0xff, 0x6c, 0x73, 0xde, 0xcc, 0xe7, 0x6d, 0x8d, 0x4, 0x19, 0x49, 0x7f, 0x47, 0x1f, 0x48, 0x15, 0xb0, 0xe8, 0x9e, 0xf2, 0x31, 0x59, 0xde, 0x34, 0xb4, 0x5b, 0xe5, 0xe0, 0x9, 0x11, 0x30, 0xc2, 0x88, 0x5b, 0x7c, 0x5d, 0x14, 0x13, 0x6f, 0x23, 0xa9, 0xd, 0xbc, 0x2d, 0x23, 0xbe, 0xd9, 0xed, 0x75, 0x4, 0x6c, 0x99, 0xdf, 0xfd, 0x70, 0x66, 0xe6, 0xee, 0xd9, 0xb1, 0x9e, 0x6e, 0x83, 0x59, 0xd5, 0xd4, 0x80, 0x59, 0x98, 0x77, 0x89, 0x43, 0x38, 0xc9, 0xaf, 0x30, 0x32, 0x9a, 0x20, 0x1b, 0x46, 0x3d, 0x67, 0x6e, 0xd7, 0x72, 0x9e, 0x4e, 0x21, 0x4f, 0xc6, 0xe0, 0xd4, 0x7b, 0x4, 0x8d, 0xa5, 0x3, 0xf6, 0x5, 0x9b, 0x6b, 0xdc, 0x2a, 0x93, 0x77, 0x28, 0xfd, 0xb4, 0x62, 0xda, 0x20, 0xe7, 0x1f, 0xab, 0x6b, 0x51, 0x43, 0x39, 0x2f, 0xa0, 0x92, 0x1, 0x6c, 0x75, 0x3e, 0xf4, 0x35, 0xfd, 0x43, 0x2e, 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+	},
+	{
+		input:       "testdata/huffman-rand-limit.in",
+		want:        "testdata/huffman-rand-limit.%s.expect",
+		wantNoInput: "testdata/huffman-rand-limit.%s.expect-noinput",
+		tokens:      []token{0x61, 0x51c00000, 0xa, 0xf8, 0x8b, 0x96, 0x76, 0x48, 0xa, 0x85, 0x94, 0x25, 0x80, 0xaf, 0xc2, 0xfe, 0x8d, 0xe8, 0x20, 0xeb, 0x17, 0x86, 0xc9, 0xb7, 0xc5, 0xde, 0x6, 0xea, 0x7d, 0x18, 0x8b, 0xe7, 0x3e, 0x7, 0xda, 0xdf, 0xff, 0x6c, 0x73, 0xde, 0xcc, 0xe7, 0x6d, 0x8d, 0x4, 0x19, 0x49, 0x7f, 0x47, 0x1f, 0x48, 0x15, 0xb0, 0xe8, 0x9e, 0xf2, 0x31, 0x59, 0xde, 0x34, 0xb4, 0x5b, 0xe5, 0xe0, 0x9, 0x11, 0x30, 0xc2, 0x88, 0x5b, 0x7c, 0x5d, 0x14, 0x13, 0x6f, 0x23, 0xa9, 0xa, 0xbc, 0x2d, 0x23, 0xbe, 0xd9, 0xed, 0x75, 0x4, 0x6c, 0x99, 0xdf, 0xfd, 0x70, 0x66, 0xe6, 0xee, 0xd9, 0xb1, 0x9e, 0x6e, 0x83, 0x59, 0xd5, 0xd4, 0x80, 0x59, 0x98, 0x77, 0x89, 0x43, 0x38, 0xc9, 0xaf, 0x30, 0x32, 0x9a, 0x20, 0x1b, 0x46, 0x3d, 0x67, 0x6e, 0xd7, 0x72, 0x9e, 0x4e, 0x21, 0x4f, 0xc6, 0xe0, 0xd4, 0x7b, 0x4, 0x8d, 0xa5, 0x3, 0xf6, 0x5, 0x9b, 0x6b, 0xdc, 0x2a, 0x93, 0x77, 0x28, 0xfd, 0xb4, 0x62, 0xda, 0x20, 0xe7, 0x1f, 0xab, 0x6b, 0x51, 0x43, 0x39, 0x2f, 0xa0, 0x92, 0x1, 0x6c, 0x75, 0x3e, 0xf4, 0x35, 0xfd, 0x43, 0x2e, 0xf7, 0xa4, 0x75, 0xda, 0xea, 0x9b, 0xa},
+	},
+	{
+		input:       "testdata/huffman-shifts.in",
+		want:        "testdata/huffman-shifts.%s.expect",
+		wantNoInput: "testdata/huffman-shifts.%s.expect-noinput",
+		tokens:      []token{0x31, 0x30, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x52400001, 0xd, 0xa, 0x32, 0x33, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7fc00001, 0x7f400001},
+	},
+	{
+		input:       "testdata/huffman-text-shift.in",
+		want:        "testdata/huffman-text-shift.%s.expect",
+		wantNoInput: "testdata/huffman-text-shift.%s.expect-noinput",
+		tokens:      []token{0x2f, 0x2f, 0x43, 0x6f, 0x70, 0x79, 0x72, 0x69, 0x67, 0x68, 0x74, 0x32, 0x30, 0x30, 0x39, 0x54, 0x68, 0x47, 0x6f, 0x41, 0x75, 0x74, 0x68, 0x6f, 0x72, 0x2e, 0x41, 0x6c, 0x6c, 0x40800016, 0x72, 0x72, 0x76, 0x64, 0x2e, 0xd, 0xa, 0x2f, 0x2f, 0x55, 0x6f, 0x66, 0x74, 0x68, 0x69, 0x6f, 0x75, 0x72, 0x63, 0x63, 0x6f, 0x64, 0x69, 0x67, 0x6f, 0x76, 0x72, 0x6e, 0x64, 0x62, 0x79, 0x42, 0x53, 0x44, 0x2d, 0x74, 0x79, 0x6c, 0x40400020, 0x6c, 0x69, 0x63, 0x6e, 0x74, 0x68, 0x74, 0x63, 0x6e, 0x62, 0x66, 0x6f, 0x75, 0x6e, 0x64, 0x69, 0x6e, 0x74, 0x68, 0x4c, 0x49, 0x43, 0x45, 0x4e, 0x53, 0x45, 0x66, 0x69, 0x6c, 0x2e, 0xd, 0xa, 0xd, 0xa, 0x70, 0x63, 0x6b, 0x67, 0x6d, 0x69, 0x6e, 0x4040000a, 0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x22, 0x6f, 0x22, 0x4040000c, 0x66, 0x75, 0x6e, 0x63, 0x6d, 0x69, 0x6e, 0x28, 0x29, 0x7b, 0xd, 0xa, 0x9, 0x76, 0x72, 0x62, 0x3d, 0x6d, 0x6b, 0x28, 0x5b, 0x5d, 0x62, 0x79, 0x74, 0x2c, 0x36, 0x35, 0x35, 0x33, 0x35, 0x29, 0xd, 0xa, 0x9, 0x66, 0x2c, 0x5f, 0x3a, 0x3d, 0x6f, 0x2e, 0x43, 0x72, 0x74, 0x28, 0x22, 0x68, 0x75, 0x66, 0x66, 0x6d, 0x6e, 0x2d, 0x6e, 0x75, 0x6c, 0x6c, 0x2d, 0x6d, 0x78, 0x2e, 0x69, 0x6e, 0x22, 0x40800021, 0x2e, 0x57, 0x72, 0x69, 0x74, 0x28, 0x62, 0x29, 0xd, 0xa, 0x7d, 0xd, 0xa, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x58, 0x78, 0x79, 0x7a, 0x21, 0x22, 0x23, 0xc2, 0xa4, 0x25, 0x26, 0x2f, 0x3f, 0x22},
+	},
+	{
+		input:       "testdata/huffman-text.in",
+		want:        "testdata/huffman-text.%s.expect",
+		wantNoInput: "testdata/huffman-text.%s.expect-noinput",
+		tokens:      []token{0x2f, 0x2f, 0x20, 0x43, 0x6f, 0x70, 0x79, 0x72, 0x69, 0x67, 0x68, 0x74, 0x20, 0x32, 0x30, 0x30, 0x39, 0x20, 0x54, 0x68, 0x65, 0x20, 0x47, 0x6f, 0x20, 0x41, 0x75, 0x74, 0x68, 0x6f, 0x72, 0x73, 0x2e, 0x20, 0x41, 0x6c, 0x6c, 0x20, 0x4080001e, 0x73, 0x20, 0x72, 0x65, 0x73, 0x65, 0x72, 0x76, 0x65, 0x64, 0x2e, 0xd, 0xa, 0x2f, 0x2f, 0x20, 0x55, 0x73, 0x65, 0x20, 0x6f, 0x66, 0x20, 0x74, 0x68, 0x69, 0x73, 0x20, 0x73, 0x6f, 0x75, 0x72, 0x63, 0x65, 0x20, 0x63, 0x6f, 0x64, 0x65, 0x20, 0x69, 0x73, 0x20, 0x67, 0x6f, 0x76, 0x65, 0x72, 0x6e, 0x65, 0x64, 0x20, 0x62, 0x79, 0x20, 0x61, 0x20, 0x42, 0x53, 0x44, 0x2d, 0x73, 0x74, 0x79, 0x6c, 0x65, 0x40800036, 0x6c, 0x69, 0x63, 0x65, 0x6e, 0x73, 0x65, 0x20, 0x74, 0x68, 0x61, 0x74, 0x20, 0x63, 0x61, 0x6e, 0x20, 0x62, 0x65, 0x20, 0x66, 0x6f, 0x75, 0x6e, 0x64, 0x20, 0x69, 0x6e, 0x20, 0x74, 0x68, 0x65, 0x20, 0x4c, 0x49, 0x43, 0x45, 0x4e, 0x53, 0x45, 0x20, 0x66, 0x69, 0x6c, 0x65, 0x2e, 0xd, 0xa, 0xd, 0xa, 0x70, 0x61, 0x63, 0x6b, 0x61, 0x67, 0x65, 0x20, 0x6d, 0x61, 0x69, 0x6e, 0x4040000f, 0x69, 0x6d, 0x70, 0x6f, 0x72, 0x74, 0x20, 0x22, 0x6f, 0x73, 0x22, 0x4040000e, 0x66, 0x75, 0x6e, 0x63, 0x4080001b, 0x28, 0x29, 0x20, 0x7b, 0xd, 0xa, 0x9, 0x76, 0x61, 0x72, 0x20, 0x62, 0x20, 0x3d, 0x20, 0x6d, 0x61, 0x6b, 0x65, 0x28, 0x5b, 0x5d, 0x62, 0x79, 0x74, 0x65, 0x2c, 0x20, 0x36, 0x35, 0x35, 0x33, 0x35, 0x29, 0xd, 0xa, 0x9, 0x66, 0x2c, 0x20, 0x5f, 0x20, 0x3a, 0x3d, 0x20, 0x6f, 0x73, 0x2e, 0x43, 0x72, 0x65, 0x61, 0x74, 0x65, 0x28, 0x22, 0x68, 0x75, 0x66, 0x66, 0x6d, 0x61, 0x6e, 0x2d, 0x6e, 0x75, 0x6c, 0x6c, 0x2d, 0x6d, 0x61, 0x78, 0x2e, 0x69, 0x6e, 0x22, 0x4080002a, 0x2e, 0x57, 0x72, 0x69, 0x74, 0x65, 0x28, 0x62, 0x29, 0xd, 0xa, 0x7d, 0xd, 0xa},
+	},
+	{
+		input:       "testdata/huffman-zero.in",
+		want:        "testdata/huffman-zero.%s.expect",
+		wantNoInput: "testdata/huffman-zero.%s.expect-noinput",
+		tokens:      []token{0x30, ml, 0x4b800000},
+	},
+	{
+		input:       "",
+		want:        "",
+		wantNoInput: "testdata/null-long-match.%s.expect-noinput",
+		tokens:      []token{0x0, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, ml, 0x41400000},
+	},
+}
+
+// TestWriteBlock tests if the writeBlock encoding has changed.
+// To update the reference files use the "-update" flag on the test.
+func TestWriteBlock(t *testing.T) {
+	for _, test := range writeBlockTests {
+		testBlock(t, test, "wb")
+	}
+}
+
+// TestWriteBlockDynamic tests if the writeBlockDynamic encoding has changed.
+// To update the reference files use the "-update" flag on the test.
+func TestWriteBlockDynamic(t *testing.T) {
+	for _, test := range writeBlockTests {
+		testBlock(t, test, "dyn")
+	}
+}
+
+// testBlock tests a block against its references,
+// or regenerate the references, if "-update" flag is set.
+func testBlock(t *testing.T, test huffTest, ttype string) {
+	if test.want != "" {
+		test.want = fmt.Sprintf(test.want, ttype)
+	}
+	test.wantNoInput = fmt.Sprintf(test.wantNoInput, ttype)
+	if *update {
+		if test.input != "" {
+			t.Logf("Updating %q", test.want)
+			input, err := ioutil.ReadFile(test.input)
+			if err != nil {
+				t.Error(err)
+				return
+			}
+
+			f, err := os.Create(test.want)
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			defer f.Close()
+			bw := newHuffmanBitWriter(f)
+			writeToType(t, ttype, bw, test.tokens, input)
+		}
+
+		t.Logf("Updating %q", test.wantNoInput)
+		f, err := os.Create(test.wantNoInput)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		defer f.Close()
+		bw := newHuffmanBitWriter(f)
+		writeToType(t, ttype, bw, test.tokens, nil)
+		return
+	}
+
+	if test.input != "" {
+		t.Logf("Testing %q", test.want)
+		input, err := ioutil.ReadFile(test.input)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		want, err := ioutil.ReadFile(test.want)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		var buf bytes.Buffer
+		bw := newHuffmanBitWriter(&buf)
+		writeToType(t, ttype, bw, test.tokens, input)
+
+		got := buf.Bytes()
+		if !bytes.Equal(got, want) {
+			t.Errorf("writeBlock did not yield expected result for file %q with input. See %q", test.want, test.want+".got")
+			if err := ioutil.WriteFile(test.want+".got", got, 0666); err != nil {
+				t.Error(err)
+			}
+		}
+		t.Log("Output ok")
+
+		// Test if the writer produces the same output after reset.
+		buf.Reset()
+		bw.reset(&buf)
+		writeToType(t, ttype, bw, test.tokens, input)
+		bw.flush()
+		got = buf.Bytes()
+		if !bytes.Equal(got, want) {
+			t.Errorf("reset: writeBlock did not yield expected result for file %q with input. See %q", test.want, test.want+".reset.got")
+			if err := ioutil.WriteFile(test.want+".reset.got", got, 0666); err != nil {
+				t.Error(err)
+			}
+			return
+		}
+		t.Log("Reset ok")
+		testWriterEOF(t, "wb", test, true)
+	}
+	t.Logf("Testing %q", test.wantNoInput)
+	wantNI, err := ioutil.ReadFile(test.wantNoInput)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	var buf bytes.Buffer
+	bw := newHuffmanBitWriter(&buf)
+	writeToType(t, ttype, bw, test.tokens, nil)
+
+	got := buf.Bytes()
+	if !bytes.Equal(got, wantNI) {
+		t.Errorf("writeBlock did not yield expected result for file %q with input. See %q", test.wantNoInput, test.wantNoInput+".got")
+		if err := ioutil.WriteFile(test.want+".got", got, 0666); err != nil {
+			t.Error(err)
+		}
+	} else if got[0]&1 == 1 {
+		t.Error("got unexpected EOF")
+		return
+	}
+
+	t.Log("Output ok")
+
+	// Test if the writer produces the same output after reset.
+	buf.Reset()
+	bw.reset(&buf)
+	writeToType(t, ttype, bw, test.tokens, nil)
+	bw.flush()
+	got = buf.Bytes()
+	if !bytes.Equal(got, wantNI) {
+		t.Errorf("reset: writeBlock did not yield expected result for file %q without input. See %q", test.want, test.want+".reset.got")
+		if err := ioutil.WriteFile(test.want+".reset.got", got, 0666); err != nil {
+			t.Error(err)
+		}
+		return
+	}
+	t.Log("Reset ok")
+	testWriterEOF(t, "wb", test, false)
+}
+
+func writeToType(t *testing.T, ttype string, bw *huffmanBitWriter, tok []token, input []byte) {
+	switch ttype {
+	case "wb":
+		bw.writeBlock(tok, false, input)
+	case "dyn":
+		bw.writeBlockDynamic(tok, false, input)
+	default:
+		panic("unknown test type")
+	}
+
+	if bw.err != nil {
+		t.Error(bw.err)
+		return
+	}
+
+	bw.flush()
+	if bw.err != nil {
+		t.Error(bw.err)
+		return
+	}
+}
+
+// testWriterEOF tests if the written block contains an EOF marker.
+func testWriterEOF(t *testing.T, ttype string, test huffTest, useInput bool) {
+	if useInput && test.input == "" {
+		return
+	}
+	var input []byte
+	if useInput {
+		var err error
+		input, err = ioutil.ReadFile(test.input)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+	}
+	var buf bytes.Buffer
+	bw := newHuffmanBitWriter(&buf)
+	switch ttype {
+	case "wb":
+		bw.writeBlock(test.tokens, true, input)
+	case "dyn":
+		bw.writeBlockDynamic(test.tokens, true, input)
+	case "huff":
+		bw.writeBlockHuff(true, input)
+	default:
+		panic("unknown test type")
+	}
+	if bw.err != nil {
+		t.Error(bw.err)
+		return
+	}
+
+	bw.flush()
+	if bw.err != nil {
+		t.Error(bw.err)
+		return
+	}
+	b := buf.Bytes()
+	if len(b) == 0 {
+		t.Error("no output received")
+		return
+	}
+	if b[0]&1 != 1 {
+		t.Errorf("block not marked with EOF for input %q", test.input)
+		return
+	}
+	t.Log("EOF ok")
+}
diff --git a/libgo/go/compress/flate/huffman_code.go b/libgo/go/compress/flate/huffman_code.go
index 50ec79c9405..bdcbd823b00 100644
--- a/libgo/go/compress/flate/huffman_code.go
+++ b/libgo/go/compress/flate/huffman_code.go
@@ -9,9 +9,17 @@ import (
 	"sort"
 )
 
+// hcode is a huffman code with a bit code and bit length.
+type hcode struct {
+	code, len uint16
+}
+
 type huffmanEncoder struct {
-	codeBits []uint8
-	code     []uint16
+	codes     []hcode
+	freqcache []literalNode
+	bitCount  [17]int32
+	lns       byLiteral // stored to avoid repeated allocation in generate
+	lfs       byFreq    // stored to avoid repeated allocation in generate
 }
 
 type literalNode struct {
@@ -39,21 +47,26 @@ type levelInfo struct {
 	needed int32
 }
 
+// set sets the code and length of an hcode.
+func (h *hcode) set(code uint16, length uint16) {
+	h.len = length
+	h.code = code
+}
+
 func maxNode() literalNode { return literalNode{math.MaxUint16, math.MaxInt32} }
 
 func newHuffmanEncoder(size int) *huffmanEncoder {
-	return &huffmanEncoder{make([]uint8, size), make([]uint16, size)}
+	return &huffmanEncoder{codes: make([]hcode, size)}
 }
 
 // Generates a HuffmanCode corresponding to the fixed literal table
 func generateFixedLiteralEncoding() *huffmanEncoder {
 	h := newHuffmanEncoder(maxNumLit)
-	codeBits := h.codeBits
-	code := h.code
+	codes := h.codes
 	var ch uint16
 	for ch = 0; ch < maxNumLit; ch++ {
 		var bits uint16
-		var size uint8
+		var size uint16
 		switch {
 		case ch < 144:
 			// size 8, 000110000  .. 10111111
@@ -75,19 +88,16 @@ func generateFixedLiteralEncoding() *huffmanEncoder {
 			bits = ch + 192 - 280
 			size = 8
 		}
-		codeBits[ch] = size
-		code[ch] = reverseBits(bits, size)
+		codes[ch] = hcode{code: reverseBits(bits, byte(size)), len: size}
 	}
 	return h
 }
 
 func generateFixedOffsetEncoding() *huffmanEncoder {
 	h := newHuffmanEncoder(30)
-	codeBits := h.codeBits
-	code := h.code
-	for ch := uint16(0); ch < 30; ch++ {
-		codeBits[ch] = 5
-		code[ch] = reverseBits(ch, 5)
+	codes := h.codes
+	for ch := range codes {
+		codes[ch] = hcode{code: reverseBits(uint16(ch), 5), len: 5}
 	}
 	return h
 }
@@ -95,11 +105,11 @@ func generateFixedOffsetEncoding() *huffmanEncoder {
 var fixedLiteralEncoding *huffmanEncoder = generateFixedLiteralEncoding()
 var fixedOffsetEncoding *huffmanEncoder = generateFixedOffsetEncoding()
 
-func (h *huffmanEncoder) bitLength(freq []int32) int64 {
-	var total int64
+func (h *huffmanEncoder) bitLength(freq []int32) int {
+	var total int
 	for i, f := range freq {
 		if f != 0 {
-			total += int64(f) * int64(h.codeBits[i])
+			total += int(f) * int(h.codes[i].len)
 		}
 	}
 	return total
@@ -113,7 +123,7 @@ const maxBitsLimit = 16
 // The cases of 0, 1, and 2 literals are handled by special case code.
 //
 // list  An array of the literals with non-zero frequencies
-//             and their associated frequencies.  The array is in order of increasing
+//             and their associated frequencies. The array is in order of increasing
 //             frequency, and has as its last element a special element with frequency
 //             MaxInt32
 // maxBits     The maximum number of bits that should be used to encode any literal.
@@ -128,7 +138,7 @@ func (h *huffmanEncoder) bitCounts(list []literalNode, maxBits int32) []int32 {
 	list = list[0 : n+1]
 	list[n] = maxNode()
 
-	// The tree can't have greater depth than n - 1, no matter what.  This
+	// The tree can't have greater depth than n - 1, no matter what. This
 	// saves a little bit of work in some small cases
 	if maxBits > n-1 {
 		maxBits = n - 1
@@ -197,7 +207,7 @@ func (h *huffmanEncoder) bitCounts(list []literalNode, maxBits int32) []int32 {
 
 		if l.needed--; l.needed == 0 {
 			// We've done everything we need to do for this level.
-			// Continue calculating one level up.  Fill in nextPairFreq
+			// Continue calculating one level up. Fill in nextPairFreq
 			// of that level with the sum of the two nodes we've just calculated on
 			// this level.
 			if l.level == maxBits {
@@ -220,7 +230,7 @@ func (h *huffmanEncoder) bitCounts(list []literalNode, maxBits int32) []int32 {
 		panic("leafCounts[maxBits][maxBits] != n")
 	}
 
-	bitCount := make([]int32, maxBits+1)
+	bitCount := h.bitCount[:maxBits+1]
 	bits := 1
 	counts := &leafCounts[maxBits]
 	for level := maxBits; level > 0; level-- {
@@ -246,10 +256,10 @@ func (h *huffmanEncoder) assignEncodingAndSize(bitCount []int32, list []literalN
 		// code, code + 1, ....  The code values are
 		// assigned in literal order (not frequency order).
 		chunk := list[len(list)-int(bits):]
-		sortByLiteral(chunk)
+
+		h.lns.sort(chunk)
 		for _, node := range chunk {
-			h.codeBits[node.literal] = uint8(n)
-			h.code[node.literal] = reverseBits(code, uint8(n))
+			h.codes[node.literal] = hcode{code: reverseBits(code, uint8(n)), len: uint16(n)}
 			code++
 		}
 		list = list[0 : len(list)-int(bits)]
@@ -261,7 +271,13 @@ func (h *huffmanEncoder) assignEncodingAndSize(bitCount []int32, list []literalN
 // freq  An array of frequencies, in which frequency[i] gives the frequency of literal i.
 // maxBits  The maximum number of bits to use for any literal.
 func (h *huffmanEncoder) generate(freq []int32, maxBits int32) {
-	list := make([]literalNode, len(freq)+1)
+	if h.freqcache == nil {
+		// Allocate a reusable buffer with the longest possible frequency table.
+		// Possible lengths are codegenCodeCount, offsetCodeCount and maxNumLit.
+		// The largest of these is maxNumLit, so we allocate for that case.
+		h.freqcache = make([]literalNode, maxNumLit+1)
+	}
+	list := h.freqcache[:len(freq)+1]
 	// Number of non-zero literals
 	count := 0
 	// Set list to be the set of all non-zero literals and their frequencies
@@ -270,23 +286,23 @@ func (h *huffmanEncoder) generate(freq []int32, maxBits int32) {
 			list[count] = literalNode{uint16(i), f}
 			count++
 		} else {
-			h.codeBits[i] = 0
+			list[count] = literalNode{}
+			h.codes[i].len = 0
 		}
 	}
-	// If freq[] is shorter than codeBits[], fill rest of codeBits[] with zeros
-	h.codeBits = h.codeBits[0:len(freq)]
-	list = list[0:count]
+	list[len(freq)] = literalNode{}
+
+	list = list[:count]
 	if count <= 2 {
-		// Handle the small cases here, because they are awkward for the general case code.  With
+		// Handle the small cases here, because they are awkward for the general case code. With
 		// two or fewer literals, everything has bit length 1.
 		for i, node := range list {
 			// "list" is in order of increasing literal value.
-			h.codeBits[node.literal] = 1
-			h.code[node.literal] = uint16(i)
+			h.codes[node.literal].set(uint16(i), 1)
 		}
 		return
 	}
-	sortByFreq(list)
+	h.lfs.sort(list)
 
 	// Get the number of literals for each bit count
 	bitCount := h.bitCounts(list, maxBits)
@@ -294,30 +310,35 @@ func (h *huffmanEncoder) generate(freq []int32, maxBits int32) {
 	h.assignEncodingAndSize(bitCount, list)
 }
 
-type literalNodeSorter struct {
-	a    []literalNode
-	less func(i, j int) bool
+type byLiteral []literalNode
+
+func (s *byLiteral) sort(a []literalNode) {
+	*s = byLiteral(a)
+	sort.Sort(s)
 }
 
-func (s literalNodeSorter) Len() int { return len(s.a) }
+func (s byLiteral) Len() int { return len(s) }
 
-func (s literalNodeSorter) Less(i, j int) bool {
-	return s.less(i, j)
+func (s byLiteral) Less(i, j int) bool {
+	return s[i].literal < s[j].literal
 }
 
-func (s literalNodeSorter) Swap(i, j int) { s.a[i], s.a[j] = s.a[j], s.a[i] }
+func (s byLiteral) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
 
-func sortByFreq(a []literalNode) {
-	s := &literalNodeSorter{a, func(i, j int) bool {
-		if a[i].freq == a[j].freq {
-			return a[i].literal < a[j].literal
-		}
-		return a[i].freq < a[j].freq
-	}}
+type byFreq []literalNode
+
+func (s *byFreq) sort(a []literalNode) {
+	*s = byFreq(a)
 	sort.Sort(s)
 }
 
-func sortByLiteral(a []literalNode) {
-	s := &literalNodeSorter{a, func(i, j int) bool { return a[i].literal < a[j].literal }}
-	sort.Sort(s)
+func (s byFreq) Len() int { return len(s) }
+
+func (s byFreq) Less(i, j int) bool {
+	if s[i].freq == s[j].freq {
+		return s[i].literal < s[j].literal
+	}
+	return s[i].freq < s[j].freq
 }
+
+func (s byFreq) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
diff --git a/libgo/go/compress/flate/inflate.go b/libgo/go/compress/flate/inflate.go
index 42261e9b618..68cc232052b 100644
--- a/libgo/go/compress/flate/inflate.go
+++ b/libgo/go/compress/flate/inflate.go
@@ -15,8 +15,7 @@ import (
 )
 
 const (
-	maxCodeLen = 16    // max length of Huffman code
-	maxHist    = 32768 // max history required
+	maxCodeLen = 16 // max length of Huffman code
 	// The next three numbers come from the RFC section 3.2.7, with the
 	// additional proviso in section 3.2.5 which implies that distance codes
 	// 30 and 31 should never occur in compressed data.
@@ -115,7 +114,7 @@ type huffmanDecoder struct {
 // trees are permitted.
 func (h *huffmanDecoder) init(bits []int) bool {
 	// Sanity enables additional runtime tests during Huffman
-	// table construction.  It's intended to be used during
+	// table construction. It's intended to be used during
 	// development to supplement the currently ad-hoc unit tests.
 	const sanity = false
 
@@ -162,7 +161,7 @@ func (h *huffmanDecoder) init(bits []int) bool {
 	// Check that the coding is complete (i.e., that we've
 	// assigned all 2-to-the-max possible bit sequences).
 	// Exception: To be compatible with zlib, we also need to
-	// accept degenerate single-code codings.  See also
+	// accept degenerate single-code codings. See also
 	// TestDegenerateHuffmanCoding.
 	if code != 1<<uint(max) && !(code == 1 && max == 1) {
 		return false
@@ -200,7 +199,7 @@ func (h *huffmanDecoder) init(bits []int) bool {
 		if n <= huffmanChunkBits {
 			for off := reverse; off < len(h.chunks); off += 1 << uint(n) {
 				// We should never need to overwrite
-				// an existing chunk.  Also, 0 is
+				// an existing chunk. Also, 0 is
 				// never a valid chunk, because the
 				// lower 4 "count" bits should be
 				// between 1 and 15.
@@ -230,7 +229,7 @@ func (h *huffmanDecoder) init(bits []int) bool {
 
 	if sanity {
 		// Above we've sanity checked that we never overwrote
-		// an existing entry.  Here we additionally check that
+		// an existing entry. Here we additionally check that
 		// we filled the tables completely.
 		for i, chunk := range h.chunks {
 			if chunk == 0 {
@@ -268,7 +267,6 @@ type decompressor struct {
 	// Input source.
 	r       Reader
 	roffset int64
-	woffset int64
 
 	// Input bits, in top of b.
 	b  uint32
@@ -282,34 +280,24 @@ type decompressor struct {
 	codebits *[numCodes]int
 
 	// Output history, buffer.
-	hist  *[maxHist]byte
-	hp    int  // current output position in buffer
-	hw    int  // have written hist[0:hw] already
-	hfull bool // buffer has filled at least once
+	dict dictDecoder
 
 	// Temporary buffer (avoids repeated allocation).
 	buf [4]byte
 
 	// Next step in the decompression,
 	// and decompression state.
-	step     func(*decompressor)
-	final    bool
-	err      error
-	toRead   []byte
-	hl, hd   *huffmanDecoder
-	copyLen  int
-	copyDist int
+	step      func(*decompressor)
+	stepState int
+	final     bool
+	err       error
+	toRead    []byte
+	hl, hd    *huffmanDecoder
+	copyLen   int
+	copyDist  int
 }
 
 func (f *decompressor) nextBlock() {
-	if f.final {
-		if f.hw != f.hp {
-			f.flush((*decompressor).nextBlock)
-			return
-		}
-		f.err = io.EOF
-		return
-	}
 	for f.nb < 1+2 {
 		if f.err = f.moreBits(); f.err != nil {
 			return
@@ -347,6 +335,9 @@ func (f *decompressor) Read(b []byte) (int, error) {
 		if len(f.toRead) > 0 {
 			n := copy(b, f.toRead)
 			f.toRead = f.toRead[n:]
+			if len(f.toRead) == 0 {
+				return n, f.err
+			}
 			return n, nil
 		}
 		if f.err != nil {
@@ -478,10 +469,24 @@ func (f *decompressor) readHuffman() error {
 
 // Decode a single Huffman block from f.
 // hl and hd are the Huffman states for the lit/length values
-// and the distance values, respectively.  If hd == nil, using the
+// and the distance values, respectively. If hd == nil, using the
 // fixed distance encoding associated with fixed Huffman blocks.
 func (f *decompressor) huffmanBlock() {
-	for {
+	const (
+		stateInit = iota // Zero value must be stateInit
+		stateDict
+	)
+
+	switch f.stepState {
+	case stateInit:
+		goto readLiteral
+	case stateDict:
+		goto copyHistory
+	}
+
+readLiteral:
+	// Read literal and/or (length, distance) according to RFC section 3.2.3.
+	{
 		v, err := f.huffSym(f.hl)
 		if err != nil {
 			f.err = err
@@ -491,17 +496,16 @@ func (f *decompressor) huffmanBlock() {
 		var length int
 		switch {
 		case v < 256:
-			f.hist[f.hp] = byte(v)
-			f.hp++
-			if f.hp == len(f.hist) {
-				// After the flush, continue this loop.
-				f.flush((*decompressor).huffmanBlock)
+			f.dict.writeByte(byte(v))
+			if f.dict.availWrite() == 0 {
+				f.toRead = f.dict.readFlush()
+				f.step = (*decompressor).huffmanBlock
+				f.stepState = stateInit
 				return
 			}
-			continue
+			goto readLiteral
 		case v == 256:
-			// Done with huffman block; read next block.
-			f.step = (*decompressor).nextBlock
+			f.finishBlock()
 			return
 		// otherwise, reference to older data
 		case v < 265:
@@ -581,61 +585,33 @@ func (f *decompressor) huffmanBlock() {
 			return
 		}
 
-		// Copy history[-dist:-dist+length] into output.
-		if dist > len(f.hist) {
-			f.err = InternalError("bad history distance")
-			return
-		}
-
 		// No check on length; encoding can be prescient.
-		if !f.hfull && dist > f.hp {
+		if dist > f.dict.histSize() {
 			f.err = CorruptInputError(f.roffset)
 			return
 		}
 
 		f.copyLen, f.copyDist = length, dist
-		if f.copyHist() {
-			return
-		}
+		goto copyHistory
 	}
-}
 
-// copyHist copies f.copyLen bytes from f.hist (f.copyDist bytes ago) to itself.
-// It reports whether the f.hist buffer is full.
-func (f *decompressor) copyHist() bool {
-	p := f.hp - f.copyDist
-	if p < 0 {
-		p += len(f.hist)
-	}
-	for f.copyLen > 0 {
-		n := f.copyLen
-		if x := len(f.hist) - f.hp; n > x {
-			n = x
-		}
-		if x := len(f.hist) - p; n > x {
-			n = x
+copyHistory:
+	// Perform a backwards copy according to RFC section 3.2.3.
+	{
+		cnt := f.dict.tryWriteCopy(f.copyDist, f.copyLen)
+		if cnt == 0 {
+			cnt = f.dict.writeCopy(f.copyDist, f.copyLen)
 		}
-		forwardCopy(f.hist[:], f.hp, p, n)
-		p += n
-		f.hp += n
-		f.copyLen -= n
-		if f.hp == len(f.hist) {
-			// After flush continue copying out of history.
-			f.flush((*decompressor).copyHuff)
-			return true
-		}
-		if p == len(f.hist) {
-			p = 0
-		}
-	}
-	return false
-}
+		f.copyLen -= cnt
 
-func (f *decompressor) copyHuff() {
-	if f.copyHist() {
-		return
+		if f.dict.availWrite() == 0 || f.copyLen > 0 {
+			f.toRead = f.dict.readFlush()
+			f.step = (*decompressor).huffmanBlock // We need to continue this work
+			f.stepState = stateDict
+			return
+		}
+		goto readLiteral
 	}
-	f.huffmanBlock()
 }
 
 // Copy a single uncompressed data block from input to output.
@@ -663,8 +639,8 @@ func (f *decompressor) dataBlock() {
 	}
 
 	if n == 0 {
-		// 0-length block means sync
-		f.flush((*decompressor).nextBlock)
+		f.toRead = f.dict.readFlush()
+		f.finishBlock()
 		return
 	}
 
@@ -675,44 +651,39 @@ func (f *decompressor) dataBlock() {
 // copyData copies f.copyLen bytes from the underlying reader into f.hist.
 // It pauses for reads when f.hist is full.
 func (f *decompressor) copyData() {
-	n := f.copyLen
-	for n > 0 {
-		m := len(f.hist) - f.hp
-		if m > n {
-			m = n
-		}
-		m, err := io.ReadFull(f.r, f.hist[f.hp:f.hp+m])
-		f.roffset += int64(m)
-		if err != nil {
-			if err == io.EOF {
-				err = io.ErrUnexpectedEOF
-			}
-			f.err = err
-			return
-		}
-		n -= m
-		f.hp += m
-		if f.hp == len(f.hist) {
-			f.copyLen = n
-			f.flush((*decompressor).copyData)
-			return
+	buf := f.dict.writeSlice()
+	if len(buf) > f.copyLen {
+		buf = buf[:f.copyLen]
+	}
+
+	cnt, err := io.ReadFull(f.r, buf)
+	f.roffset += int64(cnt)
+	f.copyLen -= cnt
+	f.dict.writeMark(cnt)
+	if err != nil {
+		if err == io.EOF {
+			err = io.ErrUnexpectedEOF
 		}
+		f.err = err
+		return
 	}
-	f.step = (*decompressor).nextBlock
-}
 
-func (f *decompressor) setDict(dict []byte) {
-	if len(dict) > len(f.hist) {
-		// Will only remember the tail.
-		dict = dict[len(dict)-len(f.hist):]
+	if f.dict.availWrite() == 0 || f.copyLen > 0 {
+		f.toRead = f.dict.readFlush()
+		f.step = (*decompressor).copyData
+		return
 	}
+	f.finishBlock()
+}
 
-	f.hp = copy(f.hist[:], dict)
-	if f.hp == len(f.hist) {
-		f.hp = 0
-		f.hfull = true
+func (f *decompressor) finishBlock() {
+	if f.final {
+		if f.dict.availRead() > 0 {
+			f.toRead = f.dict.readFlush()
+		}
+		f.err = io.EOF
 	}
-	f.hw = f.hp
+	f.step = (*decompressor).nextBlock
 }
 
 func (f *decompressor) moreBits() error {
@@ -760,19 +731,6 @@ func (f *decompressor) huffSym(h *huffmanDecoder) (int, error) {
 	}
 }
 
-// Flush any buffered output to the underlying writer.
-func (f *decompressor) flush(step func(*decompressor)) {
-	f.toRead = f.hist[f.hw:f.hp]
-	f.woffset += int64(f.hp - f.hw)
-	f.hw = f.hp
-	if f.hp == len(f.hist) {
-		f.hp = 0
-		f.hw = 0
-		f.hfull = true
-	}
-	f.step = step
-}
-
 func makeReader(r io.Reader) Reader {
 	if rr, ok := r.(Reader); ok {
 		return rr
@@ -805,12 +763,10 @@ func (f *decompressor) Reset(r io.Reader, dict []byte) error {
 		r:        makeReader(r),
 		bits:     f.bits,
 		codebits: f.codebits,
-		hist:     f.hist,
+		dict:     f.dict,
 		step:     (*decompressor).nextBlock,
 	}
-	if dict != nil {
-		f.setDict(dict)
-	}
+	f.dict.init(maxMatchOffset, dict)
 	return nil
 }
 
@@ -827,17 +783,17 @@ func NewReader(r io.Reader) io.ReadCloser {
 
 	var f decompressor
 	f.r = makeReader(r)
-	f.hist = new([maxHist]byte)
 	f.bits = new([maxNumLit + maxNumDist]int)
 	f.codebits = new([numCodes]int)
 	f.step = (*decompressor).nextBlock
+	f.dict.init(maxMatchOffset, nil)
 	return &f
 }
 
 // NewReaderDict is like NewReader but initializes the reader
-// with a preset dictionary.  The returned Reader behaves as if
+// with a preset dictionary. The returned Reader behaves as if
 // the uncompressed data stream started with the given dictionary,
-// which has already been read.  NewReaderDict is typically used
+// which has already been read. NewReaderDict is typically used
 // to read data compressed by NewWriterDict.
 //
 // The ReadCloser returned by NewReader also implements Resetter.
@@ -846,10 +802,9 @@ func NewReaderDict(r io.Reader, dict []byte) io.ReadCloser {
 
 	var f decompressor
 	f.r = makeReader(r)
-	f.hist = new([maxHist]byte)
 	f.bits = new([maxNumLit + maxNumDist]int)
 	f.codebits = new([numCodes]int)
 	f.step = (*decompressor).nextBlock
-	f.setDict(dict)
+	f.dict.init(maxMatchOffset, dict)
 	return &f
 }
diff --git a/libgo/go/compress/flate/inflate_test.go b/libgo/go/compress/flate/inflate_test.go
index 9f25d30b35c..e0bce71d6f2 100644
--- a/libgo/go/compress/flate/inflate_test.go
+++ b/libgo/go/compress/flate/inflate_test.go
@@ -37,3 +37,33 @@ func TestReset(t *testing.T) {
 		}
 	}
 }
+
+func TestResetDict(t *testing.T) {
+	dict := []byte("the lorem fox")
+	ss := []string{
+		"lorem ipsum izzle fo rizzle",
+		"the quick brown fox jumped over",
+	}
+
+	deflated := make([]bytes.Buffer, len(ss))
+	for i, s := range ss {
+		w, _ := NewWriterDict(&deflated[i], DefaultCompression, dict)
+		w.Write([]byte(s))
+		w.Close()
+	}
+
+	inflated := make([]bytes.Buffer, len(ss))
+
+	f := NewReader(nil)
+	for i := range inflated {
+		f.(Resetter).Reset(&deflated[i], dict)
+		io.Copy(&inflated[i], f)
+	}
+	f.Close()
+
+	for i, s := range ss {
+		if s != inflated[i].String() {
+			t.Errorf("inflated[%d]:\ngot  %q\nwant %q", i, inflated[i], s)
+		}
+	}
+}
diff --git a/libgo/go/compress/flate/reader_test.go b/libgo/go/compress/flate/reader_test.go
index bd8873239df..b0a16ce18b9 100644
--- a/libgo/go/compress/flate/reader_test.go
+++ b/libgo/go/compress/flate/reader_test.go
@@ -22,75 +22,77 @@ func TestNlitOutOfRange(t *testing.T) {
 			"\x75\xc4\xf8\x0f\x12\x11\xb9\xb4\x4b\x09\xa0\xbe\x8b\x91\x4c")))
 }
 
-const (
-	digits = iota
-	twain
-)
-
-var testfiles = []string{
+var suites = []struct{ name, file string }{
 	// Digits is the digits of the irrational number e. Its decimal representation
 	// does not repeat, but there are only 10 possible digits, so it should be
 	// reasonably compressible.
-	digits: "../testdata/e.txt",
+	{"Digits", "../testdata/e.txt"},
 	// Twain is Mark Twain's classic English novel.
-	twain: "../testdata/Mark.Twain-Tom.Sawyer.txt",
+	{"Twain", "../testdata/Mark.Twain-Tom.Sawyer.txt"},
 }
 
-func benchmarkDecode(b *testing.B, testfile, level, n int) {
-	b.ReportAllocs()
-	b.StopTimer()
-	b.SetBytes(int64(n))
-	buf0, err := ioutil.ReadFile(testfiles[testfile])
-	if err != nil {
-		b.Fatal(err)
-	}
-	if len(buf0) == 0 {
-		b.Fatalf("test file %q has no data", testfiles[testfile])
-	}
-	compressed := new(bytes.Buffer)
-	w, err := NewWriter(compressed, level)
-	if err != nil {
-		b.Fatal(err)
-	}
-	for i := 0; i < n; i += len(buf0) {
-		if len(buf0) > n-i {
-			buf0 = buf0[:n-i]
+func BenchmarkDecode(b *testing.B) {
+	doBench(b, func(b *testing.B, buf0 []byte, level, n int) {
+		b.ReportAllocs()
+		b.StopTimer()
+		b.SetBytes(int64(n))
+
+		compressed := new(bytes.Buffer)
+		w, err := NewWriter(compressed, level)
+		if err != nil {
+			b.Fatal(err)
 		}
-		io.Copy(w, bytes.NewReader(buf0))
-	}
-	w.Close()
-	buf1 := compressed.Bytes()
-	buf0, compressed, w = nil, nil, nil
-	runtime.GC()
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		io.Copy(ioutil.Discard, NewReader(bytes.NewReader(buf1)))
-	}
+		for i := 0; i < n; i += len(buf0) {
+			if len(buf0) > n-i {
+				buf0 = buf0[:n-i]
+			}
+			io.Copy(w, bytes.NewReader(buf0))
+		}
+		w.Close()
+		buf1 := compressed.Bytes()
+		buf0, compressed, w = nil, nil, nil
+		runtime.GC()
+		b.StartTimer()
+		for i := 0; i < b.N; i++ {
+			io.Copy(ioutil.Discard, NewReader(bytes.NewReader(buf1)))
+		}
+	})
 }
 
-// These short names are so that gofmt doesn't break the BenchmarkXxx function
-// bodies below over multiple lines.
-const (
-	speed    = BestSpeed
-	default_ = DefaultCompression
-	compress = BestCompression
-)
+var levelTests = []struct {
+	name  string
+	level int
+}{
+	{"Huffman", HuffmanOnly},
+	{"Speed", BestSpeed},
+	{"Default", DefaultCompression},
+	{"Compression", BestCompression},
+}
 
-func BenchmarkDecodeDigitsSpeed1e4(b *testing.B)    { benchmarkDecode(b, digits, speed, 1e4) }
-func BenchmarkDecodeDigitsSpeed1e5(b *testing.B)    { benchmarkDecode(b, digits, speed, 1e5) }
-func BenchmarkDecodeDigitsSpeed1e6(b *testing.B)    { benchmarkDecode(b, digits, speed, 1e6) }
-func BenchmarkDecodeDigitsDefault1e4(b *testing.B)  { benchmarkDecode(b, digits, default_, 1e4) }
-func BenchmarkDecodeDigitsDefault1e5(b *testing.B)  { benchmarkDecode(b, digits, default_, 1e5) }
-func BenchmarkDecodeDigitsDefault1e6(b *testing.B)  { benchmarkDecode(b, digits, default_, 1e6) }
-func BenchmarkDecodeDigitsCompress1e4(b *testing.B) { benchmarkDecode(b, digits, compress, 1e4) }
-func BenchmarkDecodeDigitsCompress1e5(b *testing.B) { benchmarkDecode(b, digits, compress, 1e5) }
-func BenchmarkDecodeDigitsCompress1e6(b *testing.B) { benchmarkDecode(b, digits, compress, 1e6) }
-func BenchmarkDecodeTwainSpeed1e4(b *testing.B)     { benchmarkDecode(b, twain, speed, 1e4) }
-func BenchmarkDecodeTwainSpeed1e5(b *testing.B)     { benchmarkDecode(b, twain, speed, 1e5) }
-func BenchmarkDecodeTwainSpeed1e6(b *testing.B)     { benchmarkDecode(b, twain, speed, 1e6) }
-func BenchmarkDecodeTwainDefault1e4(b *testing.B)   { benchmarkDecode(b, twain, default_, 1e4) }
-func BenchmarkDecodeTwainDefault1e5(b *testing.B)   { benchmarkDecode(b, twain, default_, 1e5) }
-func BenchmarkDecodeTwainDefault1e6(b *testing.B)   { benchmarkDecode(b, twain, default_, 1e6) }
-func BenchmarkDecodeTwainCompress1e4(b *testing.B)  { benchmarkDecode(b, twain, compress, 1e4) }
-func BenchmarkDecodeTwainCompress1e5(b *testing.B)  { benchmarkDecode(b, twain, compress, 1e5) }
-func BenchmarkDecodeTwainCompress1e6(b *testing.B)  { benchmarkDecode(b, twain, compress, 1e6) }
+var sizes = []struct {
+	name string
+	n    int
+}{
+	{"1e4", 1e4},
+	{"1e5", 1e5},
+	{"1e6", 1e6},
+}
+
+func doBench(b *testing.B, f func(b *testing.B, buf []byte, level, n int)) {
+	for _, suite := range suites {
+		buf, err := ioutil.ReadFile(suite.file)
+		if err != nil {
+			b.Fatal(err)
+		}
+		if len(buf) == 0 {
+			b.Fatalf("test file %q has no data", suite.file)
+		}
+		for _, l := range levelTests {
+			for _, s := range sizes {
+				b.Run(suite.name+"/"+l.name+"/"+s.name, func(b *testing.B) {
+					f(b, buf, l.level, s.n)
+				})
+			}
+		}
+	}
+}
diff --git a/libgo/go/compress/flate/reverse_bits.go b/libgo/go/compress/flate/reverse_bits.go
index c1a02720d1a..6b222900c1e 100644
--- a/libgo/go/compress/flate/reverse_bits.go
+++ b/libgo/go/compress/flate/reverse_bits.go
@@ -44,5 +44,5 @@ func reverseUint16(v uint16) uint16 {
 }
 
 func reverseBits(number uint16, bitLength byte) uint16 {
-	return reverseUint16(number << uint8(16-bitLength))
+	return reverseUint16(number << (16 - bitLength))
 }
diff --git a/libgo/go/compress/flate/testdata/huffman-null-max.dyn.expect b/libgo/go/compress/flate/testdata/huffman-null-max.dyn.expect
new file mode 100644
index 00000000000..c08165143f2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-null-max.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-null-max.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-null-max.dyn.expect-noinput
new file mode 100644
index 00000000000..c08165143f2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-null-max.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-null-max.golden b/libgo/go/compress/flate/testdata/huffman-null-max.golden
new file mode 100644
index 00000000000..db422ca3983
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-null-max.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-null-max.in b/libgo/go/compress/flate/testdata/huffman-null-max.in
new file mode 100644
index 00000000000..5dfddf075be
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-null-max.in
diff --git a/libgo/go/compress/flate/testdata/huffman-null-max.wb.expect b/libgo/go/compress/flate/testdata/huffman-null-max.wb.expect
new file mode 100644
index 00000000000..c08165143f2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-null-max.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-null-max.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-null-max.wb.expect-noinput
new file mode 100644
index 00000000000..c08165143f2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-null-max.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-pi.dyn.expect b/libgo/go/compress/flate/testdata/huffman-pi.dyn.expect
new file mode 100644
index 00000000000..e4396ac6fe5
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-pi.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-pi.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-pi.dyn.expect-noinput
new file mode 100644
index 00000000000..e4396ac6fe5
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-pi.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-pi.golden b/libgo/go/compress/flate/testdata/huffman-pi.golden
new file mode 100644
index 00000000000..23d8f7f98b5
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-pi.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-pi.in b/libgo/go/compress/flate/testdata/huffman-pi.in
new file mode 100644
index 00000000000..efaed43431a
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-pi.in
@@ -0,0 +1 @@
+3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282306647093844609550582231725359408128481117450284102701938521105559644622948954930381964428810975665933446128475648233786783165271201909145648566923460348610454326648213393607260249141273724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609433057270365759591953092186117381932611793105118548074462379962749567351885752724891227938183011949129833673362440656643086021394946395224737190702179860943702770539217176293176752384674818467669405132000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923542019956112129021960864034418159813629774771309960518707211349999998372978049951059731732816096318595024459455346908302642522308253344685035261931188171010003137838752886587533208381420617177669147303598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909216420198938095257201065485863278865936153381827968230301952035301852968995773622599413891249721775283479131515574857242454150695950829533116861727855889075098381754637464939319255060400927701671139009848824012858361603563707660104710181942955596198946767837449448255379774726847104047534646208046684259069491293313677028989152104752162056966024058038150193511253382430035587640247496473263914199272604269922796782354781636009341721641219924586315030286182974555706749838505494588586926995690927210797509302955321165344987202755960236480665499119881834797753566369807426542527862551818417574672890977772793800081647060016145249192173217214772350141441973568548161361157352552133475741849468438523323907394143334547762416862518983569485562099219222184272550254256887671790494601653466804988627232791786085784383827967976681454100953883786360950680064225125205117392984896084128488626945604241965285022210661186306744278622039194945047123713786960956364371917287467764657573962413890865832645995813390478027590099465764078951269468398352595709825822620522489407726719478268482601476990902640136394437455305068203496252451749399651431429809190659250937221696461515709858387410597885959772975498930161753928468138268683868942774155991855925245953959431049972524680845987273644695848653836736222626099124608051243884390451244136549762780797715691435997700129616089441694868555848406353422072225828488648158456028506016842739452267467678895252138522549954666727823986456596116354886230577456498035593634568174324112515076069479451096596094025228879710893145669136867228748940560101503308617928680920874760917824938589009714909675985261365549781893129784821682998948722658804857564014270477555132379641451523746234364542858444795265867821051141354735739523113427166102135969536231442952484937187110145765403590279934403742007310578539062198387447808478489683321445713868751943506430218453191048481005370614680674919278191197939952061419663428754440643745123718192179998391015919561814675142691239748940907186494231961567945208095146550225231603881930142093762137855956638937787083039069792077346722182562599661501421503068038447734549202605414665925201497442850732518666002132434088190710486331734649651453905796268561005508106658796998163574736384052571459102897064140110971206280439039759515677157700420337869936007230558763176359421873125147120532928191826186125867321579198414848829164470609575270695722091756711672291098169091528017350671274858322287183520935396572512108357915136988209144421006751033467110314126711136990865851639831501970165151168517143765761835155650884909989859982387345528331635507647918535893226185489632132933089857064204675259070915481416549859461637180
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-pi.wb.expect b/libgo/go/compress/flate/testdata/huffman-pi.wb.expect
new file mode 100644
index 00000000000..e4396ac6fe5
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-pi.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-pi.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-pi.wb.expect-noinput
new file mode 100644
index 00000000000..e4396ac6fe5
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-pi.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-1k.dyn.expect b/libgo/go/compress/flate/testdata/huffman-rand-1k.dyn.expect
new file mode 100644
index 00000000000..09dc798ee37
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-1k.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-1k.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-rand-1k.dyn.expect-noinput
new file mode 100644
index 00000000000..0c24742fde2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-1k.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-1k.golden b/libgo/go/compress/flate/testdata/huffman-rand-1k.golden
new file mode 100644
index 00000000000..09dc798ee37
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-1k.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-1k.in b/libgo/go/compress/flate/testdata/huffman-rand-1k.in
new file mode 100644
index 00000000000..ce038ebb5bd
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-1k.in
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-1k.wb.expect b/libgo/go/compress/flate/testdata/huffman-rand-1k.wb.expect
new file mode 100644
index 00000000000..09dc798ee37
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-1k.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-1k.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-rand-1k.wb.expect-noinput
new file mode 100644
index 00000000000..0c24742fde2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-1k.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-limit.dyn.expect b/libgo/go/compress/flate/testdata/huffman-rand-limit.dyn.expect
new file mode 100644
index 00000000000..2d6527934e9
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-limit.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-limit.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-rand-limit.dyn.expect-noinput
new file mode 100644
index 00000000000..2d6527934e9
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-limit.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-limit.golden b/libgo/go/compress/flate/testdata/huffman-rand-limit.golden
new file mode 100644
index 00000000000..57e59322e98
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-limit.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-limit.in b/libgo/go/compress/flate/testdata/huffman-rand-limit.in
new file mode 100644
index 00000000000..fb5b1be6198
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-limit.in
@@ -0,0 +1,4 @@
+aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+���vH
+��%������ ��ɷ���}��>���ls���m�IGH���1Y�4�[��	0ˆ[|]o#�
+�-#���ul���pf��ٱ�n�Y�ԀY�w�C8ɯ02� F=gn�r�N!O���{����k�*�w(��b� ��kQC9/��
lu>�5�C.��u��
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-limit.wb.expect b/libgo/go/compress/flate/testdata/huffman-rand-limit.wb.expect
new file mode 100644
index 00000000000..881e59c9ab9
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-limit.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-limit.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-rand-limit.wb.expect-noinput
new file mode 100644
index 00000000000..881e59c9ab9
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-limit.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-max.golden b/libgo/go/compress/flate/testdata/huffman-rand-max.golden
new file mode 100644
index 00000000000..47d53c89c07
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-max.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-rand-max.in b/libgo/go/compress/flate/testdata/huffman-rand-max.in
new file mode 100644
index 00000000000..8418633d2ac
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-rand-max.in
diff --git a/libgo/go/compress/flate/testdata/huffman-shifts.dyn.expect b/libgo/go/compress/flate/testdata/huffman-shifts.dyn.expect
new file mode 100644
index 00000000000..7812c1c62da
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-shifts.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-shifts.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-shifts.dyn.expect-noinput
new file mode 100644
index 00000000000..7812c1c62da
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-shifts.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-shifts.golden b/libgo/go/compress/flate/testdata/huffman-shifts.golden
new file mode 100644
index 00000000000..f5133778e1c
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-shifts.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-shifts.in b/libgo/go/compress/flate/testdata/huffman-shifts.in
new file mode 100644
index 00000000000..7c7a50d1583
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-shifts.in
@@ -0,0 +1,2 @@
+101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010

+232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323232323
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-shifts.wb.expect b/libgo/go/compress/flate/testdata/huffman-shifts.wb.expect
new file mode 100644
index 00000000000..7812c1c62da
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-shifts.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-shifts.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-shifts.wb.expect-noinput
new file mode 100644
index 00000000000..7812c1c62da
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-shifts.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-text-shift.dyn.expect b/libgo/go/compress/flate/testdata/huffman-text-shift.dyn.expect
new file mode 100644
index 00000000000..71ce3aeb75a
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text-shift.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-text-shift.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-text-shift.dyn.expect-noinput
new file mode 100644
index 00000000000..71ce3aeb75a
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text-shift.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-text-shift.golden b/libgo/go/compress/flate/testdata/huffman-text-shift.golden
new file mode 100644
index 00000000000..ff023114bbc
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text-shift.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-text-shift.in b/libgo/go/compress/flate/testdata/huffman-text-shift.in
new file mode 100644
index 00000000000..cc5c3ad69d2
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text-shift.in
@@ -0,0 +1,14 @@
+//Copyright2009ThGoAuthor.Allrightrrvd.

+//UofthiourccodigovrndbyBSD-tyl

+//licnthtcnbfoundinthLICENSEfil.

+

+pckgmin

+

+import"o"

+

+funcmin(){

+	vrb=mk([]byt,65535)

+	f,_:=o.Crt("huffmn-null-mx.in")

+	f.Writ(b)

+}

+ABCDEFGHIJKLMNOPQRSTUVXxyz!"#¤%&/?"
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-text-shift.wb.expect b/libgo/go/compress/flate/testdata/huffman-text-shift.wb.expect
new file mode 100644
index 00000000000..71ce3aeb75a
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text-shift.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-text-shift.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-text-shift.wb.expect-noinput
new file mode 100644
index 00000000000..71ce3aeb75a
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text-shift.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-text.dyn.expect b/libgo/go/compress/flate/testdata/huffman-text.dyn.expect
new file mode 100644
index 00000000000..d448727c323
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text.dyn.expect
@@ -0,0 +1 @@
+�_K�0������`K��0Aasě)^�H�����Iɟb߻��_>�4
a��=����-^
�1`_�	1	���	�ő:�Y��-�F66!�A��`�a��C;A����Nyr4ߜU�!���GKС��#�����r:B[G�3��.�L��׶�bFRuM]���^⇳�(#Z������i�����v��B����B�H2S]��u/���ֽ��W�T�G��n���r�
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-text.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-text.dyn.expect-noinput
new file mode 100644
index 00000000000..d448727c323
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text.dyn.expect-noinput
@@ -0,0 +1 @@
+�_K�0������`K��0Aasě)^�H�����Iɟb߻��_>�4
a��=����-^
�1`_�	1	���	�ő:�Y��-�F66!�A��`�a��C;A����Nyr4ߜU�!���GKС��#�����r:B[G�3��.�L��׶�bFRuM]���^⇳�(#Z������i�����v��B����B�H2S]��u/���ֽ��W�T�G��n���r�
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-text.golden b/libgo/go/compress/flate/testdata/huffman-text.golden
new file mode 100644
index 00000000000..6d34c61fe0d
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text.golden
@@ -0,0 +1,3 @@
+�AK�0��x�ß�Z���LP�a�!�x��AD��I�&#I�E�����p]�Lƿ���F�p��	1�88�h��$���5S��-	�F66!�)v�.��0�Y�������&��	S���N|d�2:��
+t�|둍���xz9������骺�����Ɏ�3��
+&&=������ô�UD�=Fu���]��q����UL+�����>FQY��LZ��o���fTߵ�EŴ��{�Yʶb�e�
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-text.in b/libgo/go/compress/flate/testdata/huffman-text.in
new file mode 100644
index 00000000000..73398b98b54
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text.in
@@ -0,0 +1,13 @@
+// Copyright 2009 The Go Authors. All rights reserved.

+// Use of this source code is governed by a BSD-style

+// license that can be found in the LICENSE file.

+

+package main

+

+import "os"

+

+func main() {

+	var b = make([]byte, 65535)

+	f, _ := os.Create("huffman-null-max.in")

+	f.Write(b)

+}

diff --git a/libgo/go/compress/flate/testdata/huffman-text.wb.expect b/libgo/go/compress/flate/testdata/huffman-text.wb.expect
new file mode 100644
index 00000000000..d448727c323
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text.wb.expect
@@ -0,0 +1 @@
+�_K�0������`K��0Aasě)^�H�����Iɟb߻��_>�4
a��=����-^
�1`_�	1	���	�ő:�Y��-�F66!�A��`�a��C;A����Nyr4ߜU�!���GKС��#�����r:B[G�3��.�L��׶�bFRuM]���^⇳�(#Z������i�����v��B����B�H2S]��u/���ֽ��W�T�G��n���r�
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-text.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-text.wb.expect-noinput
new file mode 100644
index 00000000000..d448727c323
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-text.wb.expect-noinput
@@ -0,0 +1 @@
+�_K�0������`K��0Aasě)^�H�����Iɟb߻��_>�4
a��=����-^
�1`_�	1	���	�ő:�Y��-�F66!�A��`�a��C;A����Nyr4ߜU�!���GKС��#�����r:B[G�3��.�L��׶�bFRuM]���^⇳�(#Z������i�����v��B����B�H2S]��u/���ֽ��W�T�G��n���r�
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-zero.dyn.expect b/libgo/go/compress/flate/testdata/huffman-zero.dyn.expect
new file mode 100644
index 00000000000..830348a79ad
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-zero.dyn.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-zero.dyn.expect-noinput b/libgo/go/compress/flate/testdata/huffman-zero.dyn.expect-noinput
new file mode 100644
index 00000000000..830348a79ad
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-zero.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/huffman-zero.golden b/libgo/go/compress/flate/testdata/huffman-zero.golden
new file mode 100644
index 00000000000..5abdbaff9a6
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-zero.golden
diff --git a/libgo/go/compress/flate/testdata/huffman-zero.in b/libgo/go/compress/flate/testdata/huffman-zero.in
new file mode 100644
index 00000000000..349be0e6ec6
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-zero.in
@@ -0,0 +1 @@
+00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
\ No newline at end of file
diff --git a/libgo/go/compress/flate/testdata/huffman-zero.wb.expect b/libgo/go/compress/flate/testdata/huffman-zero.wb.expect
new file mode 100644
index 00000000000..dbe401c54c4
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-zero.wb.expect
diff --git a/libgo/go/compress/flate/testdata/huffman-zero.wb.expect-noinput b/libgo/go/compress/flate/testdata/huffman-zero.wb.expect-noinput
new file mode 100644
index 00000000000..dbe401c54c4
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/huffman-zero.wb.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/null-long-match.dyn.expect-noinput b/libgo/go/compress/flate/testdata/null-long-match.dyn.expect-noinput
new file mode 100644
index 00000000000..8b92d9fc20f
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/null-long-match.dyn.expect-noinput
diff --git a/libgo/go/compress/flate/testdata/null-long-match.wb.expect-noinput b/libgo/go/compress/flate/testdata/null-long-match.wb.expect-noinput
new file mode 100644
index 00000000000..8b92d9fc20f
--- /dev/null
+++ b/libgo/go/compress/flate/testdata/null-long-match.wb.expect-noinput
diff --git a/libgo/go/compress/flate/token.go b/libgo/go/compress/flate/token.go
index c485939d345..ae01391f9cf 100644
--- a/libgo/go/compress/flate/token.go
+++ b/libgo/go/compress/flate/token.go
@@ -75,9 +75,6 @@ func matchToken(xlength uint32, xoffset uint32) token {
 	return token(matchType + xlength<<lengthShift + xoffset)
 }
 
-// Returns the type of a token
-func (t token) typ() uint32 { return uint32(t) & typeMask }
-
 // Returns the literal of a literal token
 func (t token) literal() uint32 { return uint32(t - literalType) }
 
diff --git a/libgo/go/compress/flate/writer_test.go b/libgo/go/compress/flate/writer_test.go
index 58431774e0e..21cd0b22eef 100644
--- a/libgo/go/compress/flate/writer_test.go
+++ b/libgo/go/compress/flate/writer_test.go
@@ -5,56 +5,168 @@
 package flate
 
 import (
+	"bytes"
+	"fmt"
+	"io"
 	"io/ioutil"
+	"math/rand"
 	"runtime"
 	"testing"
 )
 
-func benchmarkEncoder(b *testing.B, testfile, level, n int) {
-	b.StopTimer()
-	b.SetBytes(int64(n))
-	buf0, err := ioutil.ReadFile(testfiles[testfile])
-	if err != nil {
-		b.Fatal(err)
-	}
-	if len(buf0) == 0 {
-		b.Fatalf("test file %q has no data", testfiles[testfile])
-	}
-	buf1 := make([]byte, n)
-	for i := 0; i < n; i += len(buf0) {
-		if len(buf0) > n-i {
-			buf0 = buf0[:n-i]
+func BenchmarkEncode(b *testing.B) {
+	doBench(b, func(b *testing.B, buf0 []byte, level, n int) {
+		b.StopTimer()
+		b.SetBytes(int64(n))
+
+		buf1 := make([]byte, n)
+		for i := 0; i < n; i += len(buf0) {
+			if len(buf0) > n-i {
+				buf0 = buf0[:n-i]
+			}
+			copy(buf1[i:], buf0)
 		}
-		copy(buf1[i:], buf0)
-	}
-	buf0 = nil
-	runtime.GC()
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
+		buf0 = nil
 		w, err := NewWriter(ioutil.Discard, level)
 		if err != nil {
 			b.Fatal(err)
 		}
-		w.Write(buf1)
-		w.Close()
+		runtime.GC()
+		b.StartTimer()
+		for i := 0; i < b.N; i++ {
+			w.Reset(ioutil.Discard)
+			w.Write(buf1)
+			w.Close()
+		}
+	})
+}
+
+// errorWriter is a writer that fails after N writes.
+type errorWriter struct {
+	N int
+}
+
+func (e *errorWriter) Write(b []byte) (int, error) {
+	if e.N <= 0 {
+		return 0, io.ErrClosedPipe
 	}
+	e.N--
+	return len(b), nil
 }
 
-func BenchmarkEncodeDigitsSpeed1e4(b *testing.B)    { benchmarkEncoder(b, digits, speed, 1e4) }
-func BenchmarkEncodeDigitsSpeed1e5(b *testing.B)    { benchmarkEncoder(b, digits, speed, 1e5) }
-func BenchmarkEncodeDigitsSpeed1e6(b *testing.B)    { benchmarkEncoder(b, digits, speed, 1e6) }
-func BenchmarkEncodeDigitsDefault1e4(b *testing.B)  { benchmarkEncoder(b, digits, default_, 1e4) }
-func BenchmarkEncodeDigitsDefault1e5(b *testing.B)  { benchmarkEncoder(b, digits, default_, 1e5) }
-func BenchmarkEncodeDigitsDefault1e6(b *testing.B)  { benchmarkEncoder(b, digits, default_, 1e6) }
-func BenchmarkEncodeDigitsCompress1e4(b *testing.B) { benchmarkEncoder(b, digits, compress, 1e4) }
-func BenchmarkEncodeDigitsCompress1e5(b *testing.B) { benchmarkEncoder(b, digits, compress, 1e5) }
-func BenchmarkEncodeDigitsCompress1e6(b *testing.B) { benchmarkEncoder(b, digits, compress, 1e6) }
-func BenchmarkEncodeTwainSpeed1e4(b *testing.B)     { benchmarkEncoder(b, twain, speed, 1e4) }
-func BenchmarkEncodeTwainSpeed1e5(b *testing.B)     { benchmarkEncoder(b, twain, speed, 1e5) }
-func BenchmarkEncodeTwainSpeed1e6(b *testing.B)     { benchmarkEncoder(b, twain, speed, 1e6) }
-func BenchmarkEncodeTwainDefault1e4(b *testing.B)   { benchmarkEncoder(b, twain, default_, 1e4) }
-func BenchmarkEncodeTwainDefault1e5(b *testing.B)   { benchmarkEncoder(b, twain, default_, 1e5) }
-func BenchmarkEncodeTwainDefault1e6(b *testing.B)   { benchmarkEncoder(b, twain, default_, 1e6) }
-func BenchmarkEncodeTwainCompress1e4(b *testing.B)  { benchmarkEncoder(b, twain, compress, 1e4) }
-func BenchmarkEncodeTwainCompress1e5(b *testing.B)  { benchmarkEncoder(b, twain, compress, 1e5) }
-func BenchmarkEncodeTwainCompress1e6(b *testing.B)  { benchmarkEncoder(b, twain, compress, 1e6) }
+// Test if errors from the underlying writer is passed upwards.
+func TestWriteError(t *testing.T) {
+	buf := new(bytes.Buffer)
+	n := 65536
+	if !testing.Short() {
+		n *= 4
+	}
+	for i := 0; i < n; i++ {
+		fmt.Fprintf(buf, "asdasfasf%d%dfghfgujyut%dyutyu\n", i, i, i)
+	}
+	in := buf.Bytes()
+	// We create our own buffer to control number of writes.
+	copyBuffer := make([]byte, 128)
+	for l := 0; l < 10; l++ {
+		for fail := 1; fail <= 256; fail *= 2 {
+			// Fail after 'fail' writes
+			ew := &errorWriter{N: fail}
+			w, err := NewWriter(ew, l)
+			if err != nil {
+				t.Fatalf("NewWriter: level %d: %v", l, err)
+			}
+			n, err := io.CopyBuffer(w, bytes.NewBuffer(in), copyBuffer)
+			if err == nil {
+				t.Fatalf("Level %d: Expected an error, writer was %#v", l, ew)
+			}
+			n2, err := w.Write([]byte{1, 2, 2, 3, 4, 5})
+			if n2 != 0 {
+				t.Fatal("Level", l, "Expected 0 length write, got", n)
+			}
+			if err == nil {
+				t.Fatal("Level", l, "Expected an error")
+			}
+			err = w.Flush()
+			if err == nil {
+				t.Fatal("Level", l, "Expected an error on flush")
+			}
+			err = w.Close()
+			if err == nil {
+				t.Fatal("Level", l, "Expected an error on close")
+			}
+
+			w.Reset(ioutil.Discard)
+			n2, err = w.Write([]byte{1, 2, 3, 4, 5, 6})
+			if err != nil {
+				t.Fatal("Level", l, "Got unexpected error after reset:", err)
+			}
+			if n2 == 0 {
+				t.Fatal("Level", l, "Got 0 length write, expected > 0")
+			}
+			if testing.Short() {
+				return
+			}
+		}
+	}
+}
+
+// Test if two runs produce identical results
+// even when writing different sizes to the Writer.
+func TestDeterministic(t *testing.T) {
+	for i := 0; i <= 9; i++ {
+		t.Run(fmt.Sprint("L", i), func(t *testing.T) { testDeterministic(i, t) })
+	}
+	t.Run("LM2", func(t *testing.T) { testDeterministic(-2, t) })
+}
+
+func testDeterministic(i int, t *testing.T) {
+	// Test so much we cross a good number of block boundaries.
+	var length = maxStoreBlockSize*30 + 500
+	if testing.Short() {
+		length /= 10
+	}
+
+	// Create a random, but compressible stream.
+	rng := rand.New(rand.NewSource(1))
+	t1 := make([]byte, length)
+	for i := range t1 {
+		t1[i] = byte(rng.Int63() & 7)
+	}
+
+	// Do our first encode.
+	var b1 bytes.Buffer
+	br := bytes.NewBuffer(t1)
+	w, err := NewWriter(&b1, i)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Use a very small prime sized buffer.
+	cbuf := make([]byte, 787)
+	_, err = io.CopyBuffer(w, br, cbuf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w.Close()
+
+	// We choose a different buffer size,
+	// bigger than a maximum block, and also a prime.
+	var b2 bytes.Buffer
+	cbuf = make([]byte, 81761)
+	br2 := bytes.NewBuffer(t1)
+	w2, err := NewWriter(&b2, i)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = io.CopyBuffer(w2, br2, cbuf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w2.Close()
+
+	b1b := b1.Bytes()
+	b2b := b2.Bytes()
+
+	if !bytes.Equal(b1b, b2b) {
+		t.Errorf("level %d did not produce deterministic result, result mismatch, len(a) = %d, len(b) = %d", i, len(b1b), len(b2b))
+	}
+}
diff --git a/libgo/go/compress/gzip/gunzip.go b/libgo/go/compress/gzip/gunzip.go
index 3d331454a69..7e640692f3f 100644
--- a/libgo/go/compress/gzip/gunzip.go
+++ b/libgo/go/compress/gzip/gunzip.go
@@ -9,8 +9,8 @@ package gzip
 import (
 	"bufio"
 	"compress/flate"
+	"encoding/binary"
 	"errors"
-	"hash"
 	"hash/crc32"
 	"io"
 	"time"
@@ -27,13 +27,6 @@ const (
 	flagComment = 1 << 4
 )
 
-func makeReader(r io.Reader) flate.Reader {
-	if rr, ok := r.(flate.Reader); ok {
-		return rr
-	}
-	return bufio.NewReader(r)
-}
-
 var (
 	// ErrChecksum is returned when reading GZIP data that has an invalid checksum.
 	ErrChecksum = errors.New("gzip: invalid checksum")
@@ -41,6 +34,16 @@ var (
 	ErrHeader = errors.New("gzip: invalid header")
 )
 
+var le = binary.LittleEndian
+
+// noEOF converts io.EOF to io.ErrUnexpectedEOF.
+func noEOF(err error) error {
+	if err == io.EOF {
+		return io.ErrUnexpectedEOF
+	}
+	return err
+}
+
 // The gzip file stores a header giving metadata about the compressed file.
 // That header is exposed as the fields of the Writer and Reader structs.
 //
@@ -58,23 +61,22 @@ type Header struct {
 // uncompressed data from a gzip-format compressed file.
 //
 // In general, a gzip file can be a concatenation of gzip files,
-// each with its own header.  Reads from the Reader
+// each with its own header. Reads from the Reader
 // return the concatenation of the uncompressed data of each.
 // Only the first header is recorded in the Reader fields.
 //
 // Gzip files store a length and checksum of the uncompressed data.
 // The Reader will return a ErrChecksum when Read
 // reaches the end of the uncompressed data if it does not
-// have the expected length or checksum.  Clients should treat data
+// have the expected length or checksum. Clients should treat data
 // returned by Read as tentative until they receive the io.EOF
 // marking the end of the data.
 type Reader struct {
 	Header       // valid after NewReader or Reader.Reset
 	r            flate.Reader
 	decompressor io.ReadCloser
-	digest       hash.Hash32
-	size         uint32
-	flg          byte
+	digest       uint32 // CRC-32, IEEE polynomial (section 8)
+	size         uint32 // Uncompressed size (section 2.3.1)
 	buf          [512]byte
 	err          error
 	multistream  bool
@@ -89,10 +91,7 @@ type Reader struct {
 // The Reader.Header fields will be valid in the Reader returned.
 func NewReader(r io.Reader) (*Reader, error) {
 	z := new(Reader)
-	z.r = makeReader(r)
-	z.multistream = true
-	z.digest = crc32.NewIEEE()
-	if err := z.readHeader(true); err != nil {
+	if err := z.Reset(r); err != nil {
 		return nil, err
 	}
 	return z, nil
@@ -102,16 +101,17 @@ func NewReader(r io.Reader) (*Reader, error) {
 // result of its original state from NewReader, but reading from r instead.
 // This permits reusing a Reader rather than allocating a new one.
 func (z *Reader) Reset(r io.Reader) error {
-	z.r = makeReader(r)
-	if z.digest == nil {
-		z.digest = crc32.NewIEEE()
+	*z = Reader{
+		decompressor: z.decompressor,
+		multistream:  true,
+	}
+	if rr, ok := r.(flate.Reader); ok {
+		z.r = rr
 	} else {
-		z.digest.Reset()
+		z.r = bufio.NewReader(r)
 	}
-	z.size = 0
-	z.err = nil
-	z.multistream = true
-	return z.readHeader(true)
+	z.Header, z.err = z.readHeader()
+	return z.err
 }
 
 // Multistream controls whether the reader supports multistream files.
@@ -134,14 +134,13 @@ func (z *Reader) Multistream(ok bool) {
 	z.multistream = ok
 }
 
-// GZIP (RFC 1952) is little-endian, unlike ZLIB (RFC 1950).
-func get4(p []byte) uint32 {
-	return uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 | uint32(p[3])<<24
-}
-
+// readString reads a NUL-terminated string from z.r.
+// It treats the bytes read as being encoded as ISO 8859-1 (Latin-1) and
+// will output a string encoded using UTF-8.
+// This method always updates z.digest with the data read.
 func (z *Reader) readString() (string, error) {
 	var err error
-	needconv := false
+	needConv := false
 	for i := 0; ; i++ {
 		if i >= len(z.buf) {
 			return "", ErrHeader
@@ -151,159 +150,138 @@ func (z *Reader) readString() (string, error) {
 			return "", err
 		}
 		if z.buf[i] > 0x7f {
-			needconv = true
+			needConv = true
 		}
 		if z.buf[i] == 0 {
-			// GZIP (RFC 1952) specifies that strings are NUL-terminated ISO 8859-1 (Latin-1).
-			if needconv {
+			// Digest covers the NUL terminator.
+			z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:i+1])
+
+			// Strings are ISO 8859-1, Latin-1 (RFC 1952, section 2.3.1).
+			if needConv {
 				s := make([]rune, 0, i)
-				for _, v := range z.buf[0:i] {
+				for _, v := range z.buf[:i] {
 					s = append(s, rune(v))
 				}
 				return string(s), nil
 			}
-			return string(z.buf[0:i]), nil
-		}
-	}
-}
-
-func (z *Reader) read2() (uint32, error) {
-	_, err := io.ReadFull(z.r, z.buf[0:2])
-	if err != nil {
-		if err == io.EOF {
-			err = io.ErrUnexpectedEOF
+			return string(z.buf[:i]), nil
 		}
-		return 0, err
 	}
-	return uint32(z.buf[0]) | uint32(z.buf[1])<<8, nil
 }
 
-func (z *Reader) readHeader(save bool) error {
-	_, err := io.ReadFull(z.r, z.buf[0:10])
-	if err != nil {
-		// RFC1952 section 2.2 says the following:
+// readHeader reads the GZIP header according to section 2.3.1.
+// This method does not set z.err.
+func (z *Reader) readHeader() (hdr Header, err error) {
+	if _, err = io.ReadFull(z.r, z.buf[:10]); err != nil {
+		// RFC 1952, section 2.2, says the following:
 		//	A gzip file consists of a series of "members" (compressed data sets).
 		//
 		// Other than this, the specification does not clarify whether a
 		// "series" is defined as "one or more" or "zero or more". To err on the
 		// side of caution, Go interprets this to mean "zero or more".
 		// Thus, it is okay to return io.EOF here.
-		return err
+		return hdr, err
 	}
 	if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate {
-		return ErrHeader
-	}
-	z.flg = z.buf[3]
-	if save {
-		z.ModTime = time.Unix(int64(get4(z.buf[4:8])), 0)
-		// z.buf[8] is xfl, ignored
-		z.OS = z.buf[9]
+		return hdr, ErrHeader
 	}
-	z.digest.Reset()
-	z.digest.Write(z.buf[0:10])
+	flg := z.buf[3]
+	hdr.ModTime = time.Unix(int64(le.Uint32(z.buf[4:8])), 0)
+	// z.buf[8] is XFL and is currently ignored.
+	hdr.OS = z.buf[9]
+	z.digest = crc32.ChecksumIEEE(z.buf[:10])
 
-	if z.flg&flagExtra != 0 {
-		n, err := z.read2()
-		if err != nil {
-			return err
+	if flg&flagExtra != 0 {
+		if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
+			return hdr, noEOF(err)
 		}
-		data := make([]byte, n)
+		z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:2])
+		data := make([]byte, le.Uint16(z.buf[:2]))
 		if _, err = io.ReadFull(z.r, data); err != nil {
-			if err == io.EOF {
-				err = io.ErrUnexpectedEOF
-			}
-			return err
-		}
-		if save {
-			z.Extra = data
+			return hdr, noEOF(err)
 		}
+		z.digest = crc32.Update(z.digest, crc32.IEEETable, data)
+		hdr.Extra = data
 	}
 
 	var s string
-	if z.flg&flagName != 0 {
+	if flg&flagName != 0 {
 		if s, err = z.readString(); err != nil {
-			return err
-		}
-		if save {
-			z.Name = s
+			return hdr, err
 		}
+		hdr.Name = s
 	}
 
-	if z.flg&flagComment != 0 {
+	if flg&flagComment != 0 {
 		if s, err = z.readString(); err != nil {
-			return err
-		}
-		if save {
-			z.Comment = s
+			return hdr, err
 		}
+		hdr.Comment = s
 	}
 
-	if z.flg&flagHdrCrc != 0 {
-		n, err := z.read2()
-		if err != nil {
-			return err
+	if flg&flagHdrCrc != 0 {
+		if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil {
+			return hdr, noEOF(err)
 		}
-		sum := z.digest.Sum32() & 0xFFFF
-		if n != sum {
-			return ErrHeader
+		digest := le.Uint16(z.buf[:2])
+		if digest != uint16(z.digest) {
+			return hdr, ErrHeader
 		}
 	}
 
-	z.digest.Reset()
+	z.digest = 0
 	if z.decompressor == nil {
 		z.decompressor = flate.NewReader(z.r)
 	} else {
 		z.decompressor.(flate.Resetter).Reset(z.r, nil)
 	}
-	return nil
+	return hdr, nil
 }
 
 func (z *Reader) Read(p []byte) (n int, err error) {
 	if z.err != nil {
 		return 0, z.err
 	}
-	if len(p) == 0 {
-		return 0, nil
-	}
 
-	n, err = z.decompressor.Read(p)
-	z.digest.Write(p[0:n])
+	n, z.err = z.decompressor.Read(p)
+	z.digest = crc32.Update(z.digest, crc32.IEEETable, p[:n])
 	z.size += uint32(n)
-	if n != 0 || err != io.EOF {
-		z.err = err
-		return
+	if z.err != io.EOF {
+		// In the normal case we return here.
+		return n, z.err
 	}
 
-	// Finished file; check checksum + size.
-	if _, err := io.ReadFull(z.r, z.buf[0:8]); err != nil {
-		if err == io.EOF {
-			err = io.ErrUnexpectedEOF
-		}
-		z.err = err
-		return 0, err
+	// Finished file; check checksum and size.
+	if _, err := io.ReadFull(z.r, z.buf[:8]); err != nil {
+		z.err = noEOF(err)
+		return n, z.err
 	}
-	crc32, isize := get4(z.buf[0:4]), get4(z.buf[4:8])
-	sum := z.digest.Sum32()
-	if sum != crc32 || isize != z.size {
+	digest := le.Uint32(z.buf[:4])
+	size := le.Uint32(z.buf[4:8])
+	if digest != z.digest || size != z.size {
 		z.err = ErrChecksum
-		return 0, z.err
+		return n, z.err
 	}
+	z.digest, z.size = 0, 0
 
-	// File is ok; is there another?
+	// File is ok; check if there is another.
 	if !z.multistream {
-		return 0, io.EOF
+		return n, io.EOF
 	}
+	z.err = nil // Remove io.EOF
 
-	if err = z.readHeader(false); err != nil {
-		z.err = err
-		return
+	if _, z.err = z.readHeader(); z.err != nil {
+		return n, z.err
 	}
 
-	// Yes.  Reset and read from it.
-	z.digest.Reset()
-	z.size = 0
+	// Read from next file, if necessary.
+	if n > 0 {
+		return n, nil
+	}
 	return z.Read(p)
 }
 
 // Close closes the Reader. It does not close the underlying io.Reader.
+// In order for the GZIP checksum to be verified, the reader must be
+// fully consumed until the io.EOF.
 func (z *Reader) Close() error { return z.decompressor.Close() }
diff --git a/libgo/go/compress/gzip/gunzip_test.go b/libgo/go/compress/gzip/gunzip_test.go
index 007d9585cee..fdce91989a6 100644
--- a/libgo/go/compress/gzip/gunzip_test.go
+++ b/libgo/go/compress/gzip/gunzip_test.go
@@ -36,6 +36,17 @@ var gunzipTests = []gunzipTest{
 		},
 		nil,
 	},
+	{
+		"",
+		"empty - with no file name",
+		"",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x00, 0x00, 0x09, 0x6e, 0x88,
+			0x00, 0xff, 0x01, 0x00, 0x00, 0xff, 0xff, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+		nil,
+	},
 	{ // has 1 non-empty fixed huffman block
 		"hello.txt",
 		"hello.txt",
@@ -281,49 +292,102 @@ var gunzipTests = []gunzipTest{
 		},
 		ErrChecksum,
 	},
+	{
+		"f1l3n4m3.tXt",
+		"header with all fields used",
+		"",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x1e, 0x70, 0xf0, 0xf9, 0x4a,
+			0x00, 0xaa, 0x09, 0x00, 0x7a, 0x7a, 0x05, 0x00,
+			0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x31, 0x6c,
+			0x33, 0x6e, 0x34, 0x6d, 0x33, 0x2e, 0x74, 0x58,
+			0x74, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
+			0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
+			0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
+			0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
+			0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26,
+			0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e,
+			0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36,
+			0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e,
+			0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46,
+			0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e,
+			0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56,
+			0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e,
+			0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
+			0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e,
+			0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76,
+			0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e,
+			0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86,
+			0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e,
+			0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96,
+			0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e,
+			0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6,
+			0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae,
+			0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
+			0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe,
+			0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6,
+			0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce,
+			0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6,
+			0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde,
+			0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6,
+			0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee,
+			0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6,
+			0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe,
+			0xff, 0x00, 0x92, 0xfd, 0x01, 0x00, 0x00, 0xff,
+			0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00,
+		},
+		nil,
+	},
 }
 
 func TestDecompressor(t *testing.T) {
+	// Keep resetting this reader.
+	// It is intended behavior that Reader.Reset can be called on a zero-value
+	// Reader and be the equivalent as if NewReader was used instead.
+	r1 := new(Reader)
+
 	b := new(bytes.Buffer)
 	for _, tt := range gunzipTests {
+		// Test NewReader.
 		in := bytes.NewReader(tt.gzip)
-		gzip, err := NewReader(in)
+		r2, err := NewReader(in)
 		if err != nil {
-			t.Errorf("%s: NewReader: %s", tt.name, err)
+			t.Errorf("%s: NewReader: %s", tt.desc, err)
 			continue
 		}
-		defer gzip.Close()
-		if tt.name != gzip.Name {
-			t.Errorf("%s: got name %s", tt.name, gzip.Name)
+		defer r2.Close()
+		if tt.name != r2.Name {
+			t.Errorf("%s: got name %s", tt.desc, r2.Name)
 		}
 		b.Reset()
-		n, err := io.Copy(b, gzip)
+		n, err := io.Copy(b, r2)
 		if err != tt.err {
-			t.Errorf("%s: io.Copy: %v want %v", tt.name, err, tt.err)
+			t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err)
 		}
 		s := b.String()
 		if s != tt.raw {
-			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.name, n, s, len(tt.raw), tt.raw)
+			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.desc, n, s, len(tt.raw), tt.raw)
 		}
 
-		// Test Reader Reset.
+		// Test Reader.Reset.
 		in = bytes.NewReader(tt.gzip)
-		err = gzip.Reset(in)
+		err = r1.Reset(in)
 		if err != nil {
-			t.Errorf("%s: Reset: %s", tt.name, err)
+			t.Errorf("%s: Reset: %s", tt.desc, err)
 			continue
 		}
-		if tt.name != gzip.Name {
-			t.Errorf("%s: got name %s", tt.name, gzip.Name)
+		if tt.name != r1.Name {
+			t.Errorf("%s: got name %s", tt.desc, r1.Name)
 		}
 		b.Reset()
-		n, err = io.Copy(b, gzip)
+		n, err = io.Copy(b, r1)
 		if err != tt.err {
-			t.Errorf("%s: io.Copy: %v want %v", tt.name, err, tt.err)
+			t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err)
 		}
 		s = b.String()
 		if s != tt.raw {
-			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.name, n, s, len(tt.raw), tt.raw)
+			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.desc, n, s, len(tt.raw), tt.raw)
 		}
 	}
 }
@@ -356,20 +420,6 @@ func TestIssue6550(t *testing.T) {
 	}
 }
 
-func TestInitialReset(t *testing.T) {
-	var r Reader
-	if err := r.Reset(bytes.NewReader(gunzipTests[1].gzip)); err != nil {
-		t.Error(err)
-	}
-	var buf bytes.Buffer
-	if _, err := io.Copy(&buf, &r); err != nil {
-		t.Error(err)
-	}
-	if s := buf.String(); s != gunzipTests[1].raw {
-		t.Errorf("got %q want %q", s, gunzipTests[1].raw)
-	}
-}
-
 func TestMultistreamFalse(t *testing.T) {
 	// Find concatenation test.
 	var tt gunzipTest
@@ -411,7 +461,7 @@ Found:
 }
 
 func TestNilStream(t *testing.T) {
-	// Go liberally interprets RFC1952 section 2.2 to mean that a gzip file
+	// Go liberally interprets RFC 1952 section 2.2 to mean that a gzip file
 	// consist of zero or more members. Thus, we test that a nil stream is okay.
 	_, err := NewReader(bytes.NewReader(nil))
 	if err != io.EOF {
diff --git a/libgo/go/compress/gzip/gzip.go b/libgo/go/compress/gzip/gzip.go
index 4d945e47fe8..c702c493c11 100644
--- a/libgo/go/compress/gzip/gzip.go
+++ b/libgo/go/compress/gzip/gzip.go
@@ -8,7 +8,6 @@ import (
 	"compress/flate"
 	"errors"
 	"fmt"
-	"hash"
 	"hash/crc32"
 	"io"
 )
@@ -30,8 +29,8 @@ type Writer struct {
 	level       int
 	wroteHeader bool
 	compressor  *flate.Writer
-	digest      hash.Hash32
-	size        uint32
+	digest      uint32 // CRC-32, IEEE polynomial (section 8)
+	size        uint32 // Uncompressed size (section 2.3.1)
 	closed      bool
 	buf         [10]byte
 	err         error
@@ -66,12 +65,6 @@ func NewWriterLevel(w io.Writer, level int) (*Writer, error) {
 }
 
 func (z *Writer) init(w io.Writer, level int) {
-	digest := z.digest
-	if digest != nil {
-		digest.Reset()
-	} else {
-		digest = crc32.NewIEEE()
-	}
 	compressor := z.compressor
 	if compressor != nil {
 		compressor.Reset(w)
@@ -82,7 +75,6 @@ func (z *Writer) init(w io.Writer, level int) {
 		},
 		w:          w,
 		level:      level,
-		digest:     digest,
 		compressor: compressor,
 	}
 }
@@ -95,26 +87,13 @@ func (z *Writer) Reset(w io.Writer) {
 	z.init(w, z.level)
 }
 
-// GZIP (RFC 1952) is little-endian, unlike ZLIB (RFC 1950).
-func put2(p []byte, v uint16) {
-	p[0] = uint8(v >> 0)
-	p[1] = uint8(v >> 8)
-}
-
-func put4(p []byte, v uint32) {
-	p[0] = uint8(v >> 0)
-	p[1] = uint8(v >> 8)
-	p[2] = uint8(v >> 16)
-	p[3] = uint8(v >> 24)
-}
-
 // writeBytes writes a length-prefixed byte slice to z.w.
 func (z *Writer) writeBytes(b []byte) error {
 	if len(b) > 0xffff {
 		return errors.New("gzip.Write: Extra data is too large")
 	}
-	put2(z.buf[0:2], uint16(len(b)))
-	_, err := z.w.Write(z.buf[0:2])
+	le.PutUint16(z.buf[:2], uint16(len(b)))
+	_, err := z.w.Write(z.buf[:2])
 	if err != nil {
 		return err
 	}
@@ -149,7 +128,7 @@ func (z *Writer) writeString(s string) (err error) {
 	}
 	// GZIP strings are NUL-terminated.
 	z.buf[0] = 0
-	_, err = z.w.Write(z.buf[0:1])
+	_, err = z.w.Write(z.buf[:1])
 	return err
 }
 
@@ -176,7 +155,7 @@ func (z *Writer) Write(p []byte) (int, error) {
 		if z.Comment != "" {
 			z.buf[3] |= 0x10
 		}
-		put4(z.buf[4:8], uint32(z.ModTime.Unix()))
+		le.PutUint32(z.buf[4:8], uint32(z.ModTime.Unix()))
 		if z.level == BestCompression {
 			z.buf[8] = 2
 		} else if z.level == BestSpeed {
@@ -185,7 +164,7 @@ func (z *Writer) Write(p []byte) (int, error) {
 			z.buf[8] = 0
 		}
 		z.buf[9] = z.OS
-		n, z.err = z.w.Write(z.buf[0:10])
+		n, z.err = z.w.Write(z.buf[:10])
 		if z.err != nil {
 			return n, z.err
 		}
@@ -212,7 +191,7 @@ func (z *Writer) Write(p []byte) (int, error) {
 		}
 	}
 	z.size += uint32(len(p))
-	z.digest.Write(p)
+	z.digest = crc32.Update(z.digest, crc32.IEEETable, p)
 	n, z.err = z.compressor.Write(p)
 	return n, z.err
 }
@@ -262,8 +241,8 @@ func (z *Writer) Close() error {
 	if z.err != nil {
 		return z.err
 	}
-	put4(z.buf[0:4], z.digest.Sum32())
-	put4(z.buf[4:8], z.size)
-	_, z.err = z.w.Write(z.buf[0:8])
+	le.PutUint32(z.buf[:4], z.digest)
+	le.PutUint32(z.buf[4:8], z.size)
+	_, z.err = z.w.Write(z.buf[:8])
 	return z.err
 }
diff --git a/libgo/go/compress/gzip/issue14937_test.go b/libgo/go/compress/gzip/issue14937_test.go
new file mode 100644
index 00000000000..432ad16b1c2
--- /dev/null
+++ b/libgo/go/compress/gzip/issue14937_test.go
@@ -0,0 +1,59 @@
+package gzip
+
+import (
+	"internal/testenv"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+)
+
+// Per golang.org/issue/14937, check that every .gz file
+// in the tree has a zero mtime.
+func TestGZIPFilesHaveZeroMTimes(t *testing.T) {
+	if testing.Short() && testenv.Builder() == "" {
+		t.Skip("skipping in short mode")
+	}
+	var files []string
+	err := filepath.Walk(runtime.GOROOT(), func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() && strings.HasSuffix(path, ".gz") {
+			files = append(files, path)
+		}
+		return nil
+	})
+	if err != nil {
+		if os.IsNotExist(err) {
+			t.Skipf("skipping: GOROOT directory not found: %s", runtime.GOROOT())
+		}
+		t.Fatal("error collecting list of .gz files in GOROOT: ", err)
+	}
+	if len(files) == 0 {
+		t.Fatal("expected to find some .gz files under GOROOT")
+	}
+	for _, path := range files {
+		checkZeroMTime(t, path)
+	}
+}
+
+func checkZeroMTime(t *testing.T, path string) {
+	f, err := os.Open(path)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	defer f.Close()
+	gz, err := NewReader(f)
+	if err != nil {
+		t.Errorf("cannot read gzip file %s: %s", path, err)
+		return
+	}
+	defer gz.Close()
+	if !gz.ModTime.Equal(time.Unix(0, 0)) {
+		t.Errorf("gzip file %s has non-zero mtime (%s)", path, gz.ModTime)
+	}
+}
diff --git a/libgo/go/compress/lzw/reader_test.go b/libgo/go/compress/lzw/reader_test.go
index c3a5c3a0aaa..6b9f9a3da70 100644
--- a/libgo/go/compress/lzw/reader_test.go
+++ b/libgo/go/compress/lzw/reader_test.go
@@ -6,8 +6,10 @@ package lzw
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"io/ioutil"
+	"math"
 	"runtime"
 	"strconv"
 	"strings"
@@ -118,42 +120,37 @@ func TestReader(t *testing.T) {
 	}
 }
 
-func benchmarkDecoder(b *testing.B, n int) {
-	b.StopTimer()
-	b.SetBytes(int64(n))
-	buf0, err := ioutil.ReadFile("../testdata/e.txt")
+func BenchmarkDecoder(b *testing.B) {
+	buf, err := ioutil.ReadFile("../testdata/e.txt")
 	if err != nil {
 		b.Fatal(err)
 	}
-	if len(buf0) == 0 {
+	if len(buf) == 0 {
 		b.Fatalf("test file has no data")
 	}
-	compressed := new(bytes.Buffer)
-	w := NewWriter(compressed, LSB, 8)
-	for i := 0; i < n; i += len(buf0) {
-		if len(buf0) > n-i {
-			buf0 = buf0[:n-i]
-		}
-		w.Write(buf0)
-	}
-	w.Close()
-	buf1 := compressed.Bytes()
-	buf0, compressed, w = nil, nil, nil
-	runtime.GC()
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		io.Copy(ioutil.Discard, NewReader(bytes.NewReader(buf1), LSB, 8))
-	}
-}
-
-func BenchmarkDecoder1e4(b *testing.B) {
-	benchmarkDecoder(b, 1e4)
-}
 
-func BenchmarkDecoder1e5(b *testing.B) {
-	benchmarkDecoder(b, 1e5)
-}
-
-func BenchmarkDecoder1e6(b *testing.B) {
-	benchmarkDecoder(b, 1e6)
+	for e := 4; e <= 6; e++ {
+		n := int(math.Pow10(e))
+		b.Run(fmt.Sprint("1e", e), func(b *testing.B) {
+			b.StopTimer()
+			b.SetBytes(int64(n))
+			buf0 := buf
+			compressed := new(bytes.Buffer)
+			w := NewWriter(compressed, LSB, 8)
+			for i := 0; i < n; i += len(buf0) {
+				if len(buf0) > n-i {
+					buf0 = buf0[:n-i]
+				}
+				w.Write(buf0)
+			}
+			w.Close()
+			buf1 := compressed.Bytes()
+			buf0, compressed, w = nil, nil, nil
+			runtime.GC()
+			b.StartTimer()
+			for i := 0; i < b.N; i++ {
+				io.Copy(ioutil.Discard, NewReader(bytes.NewReader(buf1), LSB, 8))
+			}
+		})
+	}
 }
diff --git a/libgo/go/compress/lzw/writer.go b/libgo/go/compress/lzw/writer.go
index 7367c29651d..6ddb335f315 100644
--- a/libgo/go/compress/lzw/writer.go
+++ b/libgo/go/compress/lzw/writer.go
@@ -119,7 +119,7 @@ func (e *encoder) incHi() error {
 		if err := e.write(e, clear); err != nil {
 			return err
 		}
-		e.width = uint(e.litWidth) + 1
+		e.width = e.litWidth + 1
 		e.hi = clear + 1
 		e.overflow = clear << 1
 		for i := range e.table {
diff --git a/libgo/go/compress/lzw/writer_test.go b/libgo/go/compress/lzw/writer_test.go
index 66d761727f4..4979f8b3521 100644
--- a/libgo/go/compress/lzw/writer_test.go
+++ b/libgo/go/compress/lzw/writer_test.go
@@ -5,9 +5,11 @@
 package lzw
 
 import (
+	"fmt"
 	"internal/testenv"
 	"io"
 	"io/ioutil"
+	"math"
 	"os"
 	"runtime"
 	"testing"
@@ -122,41 +124,34 @@ func TestSmallLitWidth(t *testing.T) {
 	}
 }
 
-func benchmarkEncoder(b *testing.B, n int) {
-	b.StopTimer()
-	b.SetBytes(int64(n))
-	buf0, err := ioutil.ReadFile("../testdata/e.txt")
+func BenchmarkEncoder(b *testing.B) {
+	buf, err := ioutil.ReadFile("../testdata/e.txt")
 	if err != nil {
 		b.Fatal(err)
 	}
-	if len(buf0) == 0 {
+	if len(buf) == 0 {
 		b.Fatalf("test file has no data")
 	}
-	buf1 := make([]byte, n)
-	for i := 0; i < n; i += len(buf0) {
-		if len(buf0) > n-i {
-			buf0 = buf0[:n-i]
+
+	for e := 4; e <= 6; e++ {
+		n := int(math.Pow10(e))
+		buf0 := buf
+		buf1 := make([]byte, n)
+		for i := 0; i < n; i += len(buf0) {
+			if len(buf0) > n-i {
+				buf0 = buf0[:n-i]
+			}
+			copy(buf1[i:], buf0)
 		}
-		copy(buf1[i:], buf0)
-	}
-	buf0 = nil
-	runtime.GC()
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		w := NewWriter(ioutil.Discard, LSB, 8)
-		w.Write(buf1)
-		w.Close()
+		buf0 = nil
+		runtime.GC()
+		b.Run(fmt.Sprint("1e", e), func(b *testing.B) {
+			b.SetBytes(int64(n))
+			for i := 0; i < b.N; i++ {
+				w := NewWriter(ioutil.Discard, LSB, 8)
+				w.Write(buf1)
+				w.Close()
+			}
+		})
 	}
 }
-
-func BenchmarkEncoder1e4(b *testing.B) {
-	benchmarkEncoder(b, 1e4)
-}
-
-func BenchmarkEncoder1e5(b *testing.B) {
-	benchmarkEncoder(b, 1e5)
-}
-
-func BenchmarkEncoder1e6(b *testing.B) {
-	benchmarkEncoder(b, 1e6)
-}
diff --git a/libgo/go/compress/zlib/reader.go b/libgo/go/compress/zlib/reader.go
index 78ea7043bce..2efa1930354 100644
--- a/libgo/go/compress/zlib/reader.go
+++ b/libgo/go/compress/zlib/reader.go
@@ -62,7 +62,8 @@ type Resetter interface {
 
 // NewReader creates a new ReadCloser.
 // Reads from the returned ReadCloser read and decompress data from r.
-// The implementation buffers input and may read more data than necessary from r.
+// If r does not implement io.ByteReader, the decompressor may read more
+// data than necessary from r.
 // It is the caller's responsibility to call Close on the ReadCloser when done.
 //
 // The ReadCloser returned by NewReader also implements Resetter.
@@ -84,19 +85,17 @@ func NewReaderDict(r io.Reader, dict []byte) (io.ReadCloser, error) {
 	return z, nil
 }
 
-func (z *reader) Read(p []byte) (n int, err error) {
+func (z *reader) Read(p []byte) (int, error) {
 	if z.err != nil {
 		return 0, z.err
 	}
-	if len(p) == 0 {
-		return 0, nil
-	}
 
-	n, err = z.decompressor.Read(p)
+	var n int
+	n, z.err = z.decompressor.Read(p)
 	z.digest.Write(p[0:n])
-	if n != 0 || err != io.EOF {
-		z.err = err
-		return
+	if z.err != io.EOF {
+		// In the normal case we return here.
+		return n, z.err
 	}
 
 	// Finished file; check checksum.
@@ -105,20 +104,22 @@ func (z *reader) Read(p []byte) (n int, err error) {
 			err = io.ErrUnexpectedEOF
 		}
 		z.err = err
-		return 0, err
+		return n, z.err
 	}
 	// ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
 	checksum := uint32(z.scratch[0])<<24 | uint32(z.scratch[1])<<16 | uint32(z.scratch[2])<<8 | uint32(z.scratch[3])
 	if checksum != z.digest.Sum32() {
 		z.err = ErrChecksum
-		return 0, z.err
+		return n, z.err
 	}
-	return
+	return n, io.EOF
 }
 
 // Calling Close does not close the wrapped io.Reader originally passed to NewReader.
+// In order for the ZLIB checksum to be verified, the reader must be
+// fully consumed until the io.EOF.
 func (z *reader) Close() error {
-	if z.err != nil {
+	if z.err != nil && z.err != io.EOF {
 		return z.err
 	}
 	z.err = z.decompressor.Close()
@@ -126,36 +127,42 @@ func (z *reader) Close() error {
 }
 
 func (z *reader) Reset(r io.Reader, dict []byte) error {
+	*z = reader{decompressor: z.decompressor}
 	if fr, ok := r.(flate.Reader); ok {
 		z.r = fr
 	} else {
 		z.r = bufio.NewReader(r)
 	}
-	_, err := io.ReadFull(z.r, z.scratch[0:2])
-	if err != nil {
-		if err == io.EOF {
-			err = io.ErrUnexpectedEOF
+
+	// Read the header (RFC 1950 section 2.2.).
+	_, z.err = io.ReadFull(z.r, z.scratch[0:2])
+	if z.err != nil {
+		if z.err == io.EOF {
+			z.err = io.ErrUnexpectedEOF
 		}
-		return err
+		return z.err
 	}
 	h := uint(z.scratch[0])<<8 | uint(z.scratch[1])
 	if (z.scratch[0]&0x0f != zlibDeflate) || (h%31 != 0) {
-		return ErrHeader
+		z.err = ErrHeader
+		return z.err
 	}
 	haveDict := z.scratch[1]&0x20 != 0
 	if haveDict {
-		_, err = io.ReadFull(z.r, z.scratch[0:4])
-		if err != nil {
-			if err == io.EOF {
-				err = io.ErrUnexpectedEOF
+		_, z.err = io.ReadFull(z.r, z.scratch[0:4])
+		if z.err != nil {
+			if z.err == io.EOF {
+				z.err = io.ErrUnexpectedEOF
 			}
-			return err
+			return z.err
 		}
 		checksum := uint32(z.scratch[0])<<24 | uint32(z.scratch[1])<<16 | uint32(z.scratch[2])<<8 | uint32(z.scratch[3])
 		if checksum != adler32.Checksum(dict) {
-			return ErrDictionary
+			z.err = ErrDictionary
+			return z.err
 		}
 	}
+
 	if z.decompressor == nil {
 		if haveDict {
 			z.decompressor = flate.NewReaderDict(z.r, dict)
diff --git a/libgo/go/compress/zlib/reader_test.go b/libgo/go/compress/zlib/reader_test.go
index 449f4460bcd..f74bff1f3cc 100644
--- a/libgo/go/compress/zlib/reader_test.go
+++ b/libgo/go/compress/zlib/reader_test.go
@@ -127,16 +127,18 @@ func TestDecompressor(t *testing.T) {
 	b := new(bytes.Buffer)
 	for _, tt := range zlibTests {
 		in := bytes.NewReader(tt.compressed)
-		zlib, err := NewReaderDict(in, tt.dict)
+		zr, err := NewReaderDict(in, tt.dict)
 		if err != nil {
 			if err != tt.err {
 				t.Errorf("%s: NewReader: %s", tt.desc, err)
 			}
 			continue
 		}
-		defer zlib.Close()
+		defer zr.Close()
+
+		// Read and verify correctness of data.
 		b.Reset()
-		n, err := io.Copy(b, zlib)
+		n, err := io.Copy(b, zr)
 		if err != nil {
 			if err != tt.err {
 				t.Errorf("%s: io.Copy: %v want %v", tt.desc, err, tt.err)
@@ -147,5 +149,13 @@ func TestDecompressor(t *testing.T) {
 		if s != tt.raw {
 			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.desc, n, s, len(tt.raw), tt.raw)
 		}
+
+		// Check for sticky errors.
+		if n, err := zr.Read([]byte{0}); n != 0 || err != io.EOF {
+			t.Errorf("%s: Read() = (%d, %v), want (0, io.EOF)", tt.desc, n, err)
+		}
+		if err := zr.Close(); err != nil {
+			t.Errorf("%s: Close() = %v, want nil", tt.desc, err)
+		}
 	}
 }
diff --git a/libgo/go/container/heap/heap.go b/libgo/go/container/heap/heap.go
index c467a11910c..5fe23b95372 100644
--- a/libgo/go/container/heap/heap.go
+++ b/libgo/go/container/heap/heap.go
@@ -25,7 +25,7 @@ import "sort"
 //	!h.Less(j, i) for 0 <= i < h.Len() and 2*i+1 <= j <= 2*i+2 and j < h.Len()
 //
 // Note that Push and Pop in this interface are for package heap's
-// implementation to call.  To add and remove things from the heap,
+// implementation to call. To add and remove things from the heap,
 // use heap.Push and heap.Pop.
 type Interface interface {
 	sort.Interface
diff --git a/libgo/go/container/heap/heap_test.go b/libgo/go/container/heap/heap_test.go
index b3d054c5f39..d41110422e9 100644
--- a/libgo/go/container/heap/heap_test.go
+++ b/libgo/go/container/heap/heap_test.go
@@ -173,7 +173,7 @@ func TestRemove2(t *testing.T) {
 
 func BenchmarkDup(b *testing.B) {
 	const n = 10000
-	h := make(myHeap, n)
+	h := make(myHeap, 0, n)
 	for i := 0; i < b.N; i++ {
 		for j := 0; j < n; j++ {
 			Push(&h, 0) // all elements are the same
diff --git a/libgo/go/container/list/list_test.go b/libgo/go/container/list/list_test.go
index 4d8bfc2bf07..e3bfe53a498 100755
--- a/libgo/go/container/list/list_test.go
+++ b/libgo/go/container/list/list_test.go
@@ -326,7 +326,7 @@ func TestInsertAfterUnknownMark(t *testing.T) {
 }
 
 // Test that a list l is not modified when calling MoveAfter or MoveBefore with a mark that is not an element of l.
-func TestMoveUnkownMark(t *testing.T) {
+func TestMoveUnknownMark(t *testing.T) {
 	var l1 List
 	e1 := l1.PushBack(1)
 
diff --git a/libgo/go/context/context.go b/libgo/go/context/context.go
new file mode 100644
index 00000000000..f8ce9ccdb85
--- /dev/null
+++ b/libgo/go/context/context.go
@@ -0,0 +1,473 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package context defines the Context type, which carries deadlines,
+// cancelation signals, and other request-scoped values across API boundaries
+// and between processes.
+//
+// Incoming requests to a server should create a Context, and outgoing
+// calls to servers should accept a Context. The chain of function
+// calls between them must propagate the Context, optionally replacing
+// it with a derived Context created using WithCancel, WithDeadline,
+// WithTimeout, or WithValue. When a Context is canceled, all
+// Contexts derived from it are also canceled.
+//
+// The WithCancel, WithDeadline, and WithTimeout functions take a
+// Context (the parent) and return a derived Context (the child) and a
+// CancelFunc. Calling the CancelFunc cancels the child and its
+// children, removes the parent's reference to the child, and stops
+// any associated timers. Failing to call the CancelFunc leaks the
+// child and its children until the parent is canceled or the timer
+// fires. The go vet tool checks that CancelFuncs are used on all
+// control-flow paths.
+//
+// Programs that use Contexts should follow these rules to keep interfaces
+// consistent across packages and enable static analysis tools to check context
+// propagation:
+//
+// Do not store Contexts inside a struct type; instead, pass a Context
+// explicitly to each function that needs it. The Context should be the first
+// parameter, typically named ctx:
+//
+// 	func DoSomething(ctx context.Context, arg Arg) error {
+// 		// ... use ctx ...
+// 	}
+//
+// Do not pass a nil Context, even if a function permits it. Pass context.TODO
+// if you are unsure about which Context to use.
+//
+// Use context Values only for request-scoped data that transits processes and
+// APIs, not for passing optional parameters to functions.
+//
+// The same Context may be passed to functions running in different goroutines;
+// Contexts are safe for simultaneous use by multiple goroutines.
+//
+// See https://blog.golang.org/context for example code for a server that uses
+// Contexts.
+package context
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+	"sync"
+	"time"
+)
+
+// A Context carries a deadline, a cancelation signal, and other values across
+// API boundaries.
+//
+// Context's methods may be called by multiple goroutines simultaneously.
+type Context interface {
+	// Deadline returns the time when work done on behalf of this context
+	// should be canceled. Deadline returns ok==false when no deadline is
+	// set. Successive calls to Deadline return the same results.
+	Deadline() (deadline time.Time, ok bool)
+
+	// Done returns a channel that's closed when work done on behalf of this
+	// context should be canceled. Done may return nil if this context can
+	// never be canceled. Successive calls to Done return the same value.
+	//
+	// WithCancel arranges for Done to be closed when cancel is called;
+	// WithDeadline arranges for Done to be closed when the deadline
+	// expires; WithTimeout arranges for Done to be closed when the timeout
+	// elapses.
+	//
+	// Done is provided for use in select statements:
+	//
+	//  // Stream generates values with DoSomething and sends them to out
+	//  // until DoSomething returns an error or ctx.Done is closed.
+	//  func Stream(ctx context.Context, out chan<- Value) error {
+	//  	for {
+	//  		v, err := DoSomething(ctx)
+	//  		if err != nil {
+	//  			return err
+	//  		}
+	//  		select {
+	//  		case <-ctx.Done():
+	//  			return ctx.Err()
+	//  		case out <- v:
+	//  		}
+	//  	}
+	//  }
+	//
+	// See https://blog.golang.org/pipelines for more examples of how to use
+	// a Done channel for cancelation.
+	Done() <-chan struct{}
+
+	// Err returns a non-nil error value after Done is closed. Err returns
+	// Canceled if the context was canceled or DeadlineExceeded if the
+	// context's deadline passed. No other values for Err are defined.
+	// After Done is closed, successive calls to Err return the same value.
+	Err() error
+
+	// Value returns the value associated with this context for key, or nil
+	// if no value is associated with key. Successive calls to Value with
+	// the same key returns the same result.
+	//
+	// Use context values only for request-scoped data that transits
+	// processes and API boundaries, not for passing optional parameters to
+	// functions.
+	//
+	// A key identifies a specific value in a Context. Functions that wish
+	// to store values in Context typically allocate a key in a global
+	// variable then use that key as the argument to context.WithValue and
+	// Context.Value. A key can be any type that supports equality;
+	// packages should define keys as an unexported type to avoid
+	// collisions.
+	//
+	// Packages that define a Context key should provide type-safe accessors
+	// for the values stored using that key:
+	//
+	// 	// Package user defines a User type that's stored in Contexts.
+	// 	package user
+	//
+	// 	import "context"
+	//
+	// 	// User is the type of value stored in the Contexts.
+	// 	type User struct {...}
+	//
+	// 	// key is an unexported type for keys defined in this package.
+	// 	// This prevents collisions with keys defined in other packages.
+	// 	type key int
+	//
+	// 	// userKey is the key for user.User values in Contexts. It is
+	// 	// unexported; clients use user.NewContext and user.FromContext
+	// 	// instead of using this key directly.
+	// 	var userKey key = 0
+	//
+	// 	// NewContext returns a new Context that carries value u.
+	// 	func NewContext(ctx context.Context, u *User) context.Context {
+	// 		return context.WithValue(ctx, userKey, u)
+	// 	}
+	//
+	// 	// FromContext returns the User value stored in ctx, if any.
+	// 	func FromContext(ctx context.Context) (*User, bool) {
+	// 		u, ok := ctx.Value(userKey).(*User)
+	// 		return u, ok
+	// 	}
+	Value(key interface{}) interface{}
+}
+
+// Canceled is the error returned by Context.Err when the context is canceled.
+var Canceled = errors.New("context canceled")
+
+// DeadlineExceeded is the error returned by Context.Err when the context's
+// deadline passes.
+var DeadlineExceeded error = deadlineExceededError{}
+
+type deadlineExceededError struct{}
+
+func (deadlineExceededError) Error() string { return "context deadline exceeded" }
+
+func (deadlineExceededError) Timeout() bool { return true }
+
+// An emptyCtx is never canceled, has no values, and has no deadline. It is not
+// struct{}, since vars of this type must have distinct addresses.
+type emptyCtx int
+
+func (*emptyCtx) Deadline() (deadline time.Time, ok bool) {
+	return
+}
+
+func (*emptyCtx) Done() <-chan struct{} {
+	return nil
+}
+
+func (*emptyCtx) Err() error {
+	return nil
+}
+
+func (*emptyCtx) Value(key interface{}) interface{} {
+	return nil
+}
+
+func (e *emptyCtx) String() string {
+	switch e {
+	case background:
+		return "context.Background"
+	case todo:
+		return "context.TODO"
+	}
+	return "unknown empty Context"
+}
+
+var (
+	background = new(emptyCtx)
+	todo       = new(emptyCtx)
+)
+
+// Background returns a non-nil, empty Context. It is never canceled, has no
+// values, and has no deadline. It is typically used by the main function,
+// initialization, and tests, and as the top-level Context for incoming
+// requests.
+func Background() Context {
+	return background
+}
+
+// TODO returns a non-nil, empty Context. Code should use context.TODO when
+// it's unclear which Context to use or it is not yet available (because the
+// surrounding function has not yet been extended to accept a Context
+// parameter). TODO is recognized by static analysis tools that determine
+// whether Contexts are propagated correctly in a program.
+func TODO() Context {
+	return todo
+}
+
+// A CancelFunc tells an operation to abandon its work.
+// A CancelFunc does not wait for the work to stop.
+// After the first call, subsequent calls to a CancelFunc do nothing.
+type CancelFunc func()
+
+// WithCancel returns a copy of parent with a new Done channel. The returned
+// context's Done channel is closed when the returned cancel function is called
+// or when the parent context's Done channel is closed, whichever happens first.
+//
+// Canceling this context releases resources associated with it, so code should
+// call cancel as soon as the operations running in this Context complete.
+func WithCancel(parent Context) (ctx Context, cancel CancelFunc) {
+	c := newCancelCtx(parent)
+	propagateCancel(parent, &c)
+	return &c, func() { c.cancel(true, Canceled) }
+}
+
+// newCancelCtx returns an initialized cancelCtx.
+func newCancelCtx(parent Context) cancelCtx {
+	return cancelCtx{
+		Context: parent,
+		done:    make(chan struct{}),
+	}
+}
+
+// propagateCancel arranges for child to be canceled when parent is.
+func propagateCancel(parent Context, child canceler) {
+	if parent.Done() == nil {
+		return // parent is never canceled
+	}
+	if p, ok := parentCancelCtx(parent); ok {
+		p.mu.Lock()
+		if p.err != nil {
+			// parent has already been canceled
+			child.cancel(false, p.err)
+		} else {
+			if p.children == nil {
+				p.children = make(map[canceler]bool)
+			}
+			p.children[child] = true
+		}
+		p.mu.Unlock()
+	} else {
+		go func() {
+			select {
+			case <-parent.Done():
+				child.cancel(false, parent.Err())
+			case <-child.Done():
+			}
+		}()
+	}
+}
+
+// parentCancelCtx follows a chain of parent references until it finds a
+// *cancelCtx. This function understands how each of the concrete types in this
+// package represents its parent.
+func parentCancelCtx(parent Context) (*cancelCtx, bool) {
+	for {
+		switch c := parent.(type) {
+		case *cancelCtx:
+			return c, true
+		case *timerCtx:
+			return &c.cancelCtx, true
+		case *valueCtx:
+			parent = c.Context
+		default:
+			return nil, false
+		}
+	}
+}
+
+// removeChild removes a context from its parent.
+func removeChild(parent Context, child canceler) {
+	p, ok := parentCancelCtx(parent)
+	if !ok {
+		return
+	}
+	p.mu.Lock()
+	if p.children != nil {
+		delete(p.children, child)
+	}
+	p.mu.Unlock()
+}
+
+// A canceler is a context type that can be canceled directly. The
+// implementations are *cancelCtx and *timerCtx.
+type canceler interface {
+	cancel(removeFromParent bool, err error)
+	Done() <-chan struct{}
+}
+
+// A cancelCtx can be canceled. When canceled, it also cancels any children
+// that implement canceler.
+type cancelCtx struct {
+	Context
+
+	done chan struct{} // closed by the first cancel call.
+
+	mu       sync.Mutex
+	children map[canceler]bool // set to nil by the first cancel call
+	err      error             // set to non-nil by the first cancel call
+}
+
+func (c *cancelCtx) Done() <-chan struct{} {
+	return c.done
+}
+
+func (c *cancelCtx) Err() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.err
+}
+
+func (c *cancelCtx) String() string {
+	return fmt.Sprintf("%v.WithCancel", c.Context)
+}
+
+// cancel closes c.done, cancels each of c's children, and, if
+// removeFromParent is true, removes c from its parent's children.
+func (c *cancelCtx) cancel(removeFromParent bool, err error) {
+	if err == nil {
+		panic("context: internal error: missing cancel error")
+	}
+	c.mu.Lock()
+	if c.err != nil {
+		c.mu.Unlock()
+		return // already canceled
+	}
+	c.err = err
+	close(c.done)
+	for child := range c.children {
+		// NOTE: acquiring the child's lock while holding parent's lock.
+		child.cancel(false, err)
+	}
+	c.children = nil
+	c.mu.Unlock()
+
+	if removeFromParent {
+		removeChild(c.Context, c)
+	}
+}
+
+// WithDeadline returns a copy of the parent context with the deadline adjusted
+// to be no later than d. If the parent's deadline is already earlier than d,
+// WithDeadline(parent, d) is semantically equivalent to parent. The returned
+// context's Done channel is closed when the deadline expires, when the returned
+// cancel function is called, or when the parent context's Done channel is
+// closed, whichever happens first.
+//
+// Canceling this context releases resources associated with it, so code should
+// call cancel as soon as the operations running in this Context complete.
+func WithDeadline(parent Context, deadline time.Time) (Context, CancelFunc) {
+	if cur, ok := parent.Deadline(); ok && cur.Before(deadline) {
+		// The current deadline is already sooner than the new one.
+		return WithCancel(parent)
+	}
+	c := &timerCtx{
+		cancelCtx: newCancelCtx(parent),
+		deadline:  deadline,
+	}
+	propagateCancel(parent, c)
+	d := deadline.Sub(time.Now())
+	if d <= 0 {
+		c.cancel(true, DeadlineExceeded) // deadline has already passed
+		return c, func() { c.cancel(true, Canceled) }
+	}
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.err == nil {
+		c.timer = time.AfterFunc(d, func() {
+			c.cancel(true, DeadlineExceeded)
+		})
+	}
+	return c, func() { c.cancel(true, Canceled) }
+}
+
+// A timerCtx carries a timer and a deadline. It embeds a cancelCtx to
+// implement Done and Err. It implements cancel by stopping its timer then
+// delegating to cancelCtx.cancel.
+type timerCtx struct {
+	cancelCtx
+	timer *time.Timer // Under cancelCtx.mu.
+
+	deadline time.Time
+}
+
+func (c *timerCtx) Deadline() (deadline time.Time, ok bool) {
+	return c.deadline, true
+}
+
+func (c *timerCtx) String() string {
+	return fmt.Sprintf("%v.WithDeadline(%s [%s])", c.cancelCtx.Context, c.deadline, c.deadline.Sub(time.Now()))
+}
+
+func (c *timerCtx) cancel(removeFromParent bool, err error) {
+	c.cancelCtx.cancel(false, err)
+	if removeFromParent {
+		// Remove this timerCtx from its parent cancelCtx's children.
+		removeChild(c.cancelCtx.Context, c)
+	}
+	c.mu.Lock()
+	if c.timer != nil {
+		c.timer.Stop()
+		c.timer = nil
+	}
+	c.mu.Unlock()
+}
+
+// WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).
+//
+// Canceling this context releases resources associated with it, so code should
+// call cancel as soon as the operations running in this Context complete:
+//
+// 	func slowOperationWithTimeout(ctx context.Context) (Result, error) {
+// 		ctx, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
+// 		defer cancel()  // releases resources if slowOperation completes before timeout elapses
+// 		return slowOperation(ctx)
+// 	}
+func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
+	return WithDeadline(parent, time.Now().Add(timeout))
+}
+
+// WithValue returns a copy of parent in which the value associated with key is
+// val.
+//
+// Use context Values only for request-scoped data that transits processes and
+// APIs, not for passing optional parameters to functions.
+//
+// The provided key must be comparable.
+func WithValue(parent Context, key, val interface{}) Context {
+	if key == nil {
+		panic("nil key")
+	}
+	if !reflect.TypeOf(key).Comparable() {
+		panic("key is not comparable")
+	}
+	return &valueCtx{parent, key, val}
+}
+
+// A valueCtx carries a key-value pair. It implements Value for that key and
+// delegates all other calls to the embedded Context.
+type valueCtx struct {
+	Context
+	key, val interface{}
+}
+
+func (c *valueCtx) String() string {
+	return fmt.Sprintf("%v.WithValue(%#v, %#v)", c.Context, c.key, c.val)
+}
+
+func (c *valueCtx) Value(key interface{}) interface{} {
+	if c.key == key {
+		return c.val
+	}
+	return c.Context.Value(key)
+}
diff --git a/libgo/go/context/context_test.go b/libgo/go/context/context_test.go
new file mode 100644
index 00000000000..90e78e57ecc
--- /dev/null
+++ b/libgo/go/context/context_test.go
@@ -0,0 +1,608 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package context
+
+import (
+	"fmt"
+	"math/rand"
+	"runtime"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+)
+
+// otherContext is a Context that's not one of the types defined in context.go.
+// This lets us test code paths that differ based on the underlying type of the
+// Context.
+type otherContext struct {
+	Context
+}
+
+func TestBackground(t *testing.T) {
+	c := Background()
+	if c == nil {
+		t.Fatalf("Background returned nil")
+	}
+	select {
+	case x := <-c.Done():
+		t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+	if got, want := fmt.Sprint(c), "context.Background"; got != want {
+		t.Errorf("Background().String() = %q want %q", got, want)
+	}
+}
+
+func TestTODO(t *testing.T) {
+	c := TODO()
+	if c == nil {
+		t.Fatalf("TODO returned nil")
+	}
+	select {
+	case x := <-c.Done():
+		t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+	if got, want := fmt.Sprint(c), "context.TODO"; got != want {
+		t.Errorf("TODO().String() = %q want %q", got, want)
+	}
+}
+
+func TestWithCancel(t *testing.T) {
+	c1, cancel := WithCancel(Background())
+
+	if got, want := fmt.Sprint(c1), "context.Background.WithCancel"; got != want {
+		t.Errorf("c1.String() = %q want %q", got, want)
+	}
+
+	o := otherContext{c1}
+	c2, _ := WithCancel(o)
+	contexts := []Context{c1, o, c2}
+
+	for i, c := range contexts {
+		if d := c.Done(); d == nil {
+			t.Errorf("c[%d].Done() == %v want non-nil", i, d)
+		}
+		if e := c.Err(); e != nil {
+			t.Errorf("c[%d].Err() == %v want nil", i, e)
+		}
+
+		select {
+		case x := <-c.Done():
+			t.Errorf("<-c.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+	}
+
+	cancel()
+	time.Sleep(100 * time.Millisecond) // let cancelation propagate
+
+	for i, c := range contexts {
+		select {
+		case <-c.Done():
+		default:
+			t.Errorf("<-c[%d].Done() blocked, but shouldn't have", i)
+		}
+		if e := c.Err(); e != Canceled {
+			t.Errorf("c[%d].Err() == %v want %v", i, e, Canceled)
+		}
+	}
+}
+
+func TestParentFinishesChild(t *testing.T) {
+	// Context tree:
+	// parent -> cancelChild
+	// parent -> valueChild -> timerChild
+	parent, cancel := WithCancel(Background())
+	cancelChild, stop := WithCancel(parent)
+	defer stop()
+	valueChild := WithValue(parent, "key", "value")
+	timerChild, stop := WithTimeout(valueChild, 10000*time.Hour)
+	defer stop()
+
+	select {
+	case x := <-parent.Done():
+		t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+	case x := <-cancelChild.Done():
+		t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
+	case x := <-timerChild.Done():
+		t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
+	case x := <-valueChild.Done():
+		t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+
+	// The parent's children should contain the two cancelable children.
+	pc := parent.(*cancelCtx)
+	cc := cancelChild.(*cancelCtx)
+	tc := timerChild.(*timerCtx)
+	pc.mu.Lock()
+	if len(pc.children) != 2 || !pc.children[cc] || !pc.children[tc] {
+		t.Errorf("bad linkage: pc.children = %v, want %v and %v",
+			pc.children, cc, tc)
+	}
+	pc.mu.Unlock()
+
+	if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+	if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+
+	cancel()
+
+	pc.mu.Lock()
+	if len(pc.children) != 0 {
+		t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
+	}
+	pc.mu.Unlock()
+
+	// parent and children should all be finished.
+	check := func(ctx Context, name string) {
+		select {
+		case <-ctx.Done():
+		default:
+			t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
+		}
+		if e := ctx.Err(); e != Canceled {
+			t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
+		}
+	}
+	check(parent, "parent")
+	check(cancelChild, "cancelChild")
+	check(valueChild, "valueChild")
+	check(timerChild, "timerChild")
+
+	// WithCancel should return a canceled context on a canceled parent.
+	precanceledChild := WithValue(parent, "key", "value")
+	select {
+	case <-precanceledChild.Done():
+	default:
+		t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
+	}
+	if e := precanceledChild.Err(); e != Canceled {
+		t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
+	}
+}
+
+func TestChildFinishesFirst(t *testing.T) {
+	cancelable, stop := WithCancel(Background())
+	defer stop()
+	for _, parent := range []Context{Background(), cancelable} {
+		child, cancel := WithCancel(parent)
+
+		select {
+		case x := <-parent.Done():
+			t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+		case x := <-child.Done():
+			t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+
+		cc := child.(*cancelCtx)
+		pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
+		if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
+			t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
+		}
+
+		if pcok {
+			pc.mu.Lock()
+			if len(pc.children) != 1 || !pc.children[cc] {
+				t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
+			}
+			pc.mu.Unlock()
+		}
+
+		cancel()
+
+		if pcok {
+			pc.mu.Lock()
+			if len(pc.children) != 0 {
+				t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
+			}
+			pc.mu.Unlock()
+		}
+
+		// child should be finished.
+		select {
+		case <-child.Done():
+		default:
+			t.Errorf("<-child.Done() blocked, but shouldn't have")
+		}
+		if e := child.Err(); e != Canceled {
+			t.Errorf("child.Err() == %v want %v", e, Canceled)
+		}
+
+		// parent should not be finished.
+		select {
+		case x := <-parent.Done():
+			t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+		if e := parent.Err(); e != nil {
+			t.Errorf("parent.Err() == %v want nil", e)
+		}
+	}
+}
+
+func testDeadline(c Context, name string, failAfter time.Duration, t *testing.T) {
+	select {
+	case <-time.After(failAfter):
+		t.Fatalf("%s: context should have timed out", name)
+	case <-c.Done():
+	}
+	if e := c.Err(); e != DeadlineExceeded {
+		t.Errorf("%s: c.Err() == %v; want %v", name, e, DeadlineExceeded)
+	}
+}
+
+func TestDeadline(t *testing.T) {
+	c, _ := WithDeadline(Background(), time.Now().Add(50*time.Millisecond))
+	if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
+		t.Errorf("c.String() = %q want prefix %q", got, prefix)
+	}
+	testDeadline(c, "WithDeadline", time.Second, t)
+
+	c, _ = WithDeadline(Background(), time.Now().Add(50*time.Millisecond))
+	o := otherContext{c}
+	testDeadline(o, "WithDeadline+otherContext", time.Second, t)
+
+	c, _ = WithDeadline(Background(), time.Now().Add(50*time.Millisecond))
+	o = otherContext{c}
+	c, _ = WithDeadline(o, time.Now().Add(4*time.Second))
+	testDeadline(c, "WithDeadline+otherContext+WithDeadline", 2*time.Second, t)
+}
+
+func TestTimeout(t *testing.T) {
+	c, _ := WithTimeout(Background(), 50*time.Millisecond)
+	if got, prefix := fmt.Sprint(c), "context.Background.WithDeadline("; !strings.HasPrefix(got, prefix) {
+		t.Errorf("c.String() = %q want prefix %q", got, prefix)
+	}
+	testDeadline(c, "WithTimeout", time.Second, t)
+
+	c, _ = WithTimeout(Background(), 50*time.Millisecond)
+	o := otherContext{c}
+	testDeadline(o, "WithTimeout+otherContext", time.Second, t)
+
+	c, _ = WithTimeout(Background(), 50*time.Millisecond)
+	o = otherContext{c}
+	c, _ = WithTimeout(o, 3*time.Second)
+	testDeadline(c, "WithTimeout+otherContext+WithTimeout", 2*time.Second, t)
+}
+
+func TestCanceledTimeout(t *testing.T) {
+	c, _ := WithTimeout(Background(), time.Second)
+	o := otherContext{c}
+	c, cancel := WithTimeout(o, 2*time.Second)
+	cancel()
+	time.Sleep(100 * time.Millisecond) // let cancelation propagate
+	select {
+	case <-c.Done():
+	default:
+		t.Errorf("<-c.Done() blocked, but shouldn't have")
+	}
+	if e := c.Err(); e != Canceled {
+		t.Errorf("c.Err() == %v want %v", e, Canceled)
+	}
+}
+
+type key1 int
+type key2 int
+
+var k1 = key1(1)
+var k2 = key2(1) // same int as k1, different type
+var k3 = key2(3) // same type as k2, different int
+
+func TestValues(t *testing.T) {
+	check := func(c Context, nm, v1, v2, v3 string) {
+		if v, ok := c.Value(k1).(string); ok == (len(v1) == 0) || v != v1 {
+			t.Errorf(`%s.Value(k1).(string) = %q, %t want %q, %t`, nm, v, ok, v1, len(v1) != 0)
+		}
+		if v, ok := c.Value(k2).(string); ok == (len(v2) == 0) || v != v2 {
+			t.Errorf(`%s.Value(k2).(string) = %q, %t want %q, %t`, nm, v, ok, v2, len(v2) != 0)
+		}
+		if v, ok := c.Value(k3).(string); ok == (len(v3) == 0) || v != v3 {
+			t.Errorf(`%s.Value(k3).(string) = %q, %t want %q, %t`, nm, v, ok, v3, len(v3) != 0)
+		}
+	}
+
+	c0 := Background()
+	check(c0, "c0", "", "", "")
+
+	c1 := WithValue(Background(), k1, "c1k1")
+	check(c1, "c1", "c1k1", "", "")
+
+	if got, want := fmt.Sprint(c1), `context.Background.WithValue(1, "c1k1")`; got != want {
+		t.Errorf("c.String() = %q want %q", got, want)
+	}
+
+	c2 := WithValue(c1, k2, "c2k2")
+	check(c2, "c2", "c1k1", "c2k2", "")
+
+	c3 := WithValue(c2, k3, "c3k3")
+	check(c3, "c2", "c1k1", "c2k2", "c3k3")
+
+	c4 := WithValue(c3, k1, nil)
+	check(c4, "c4", "", "c2k2", "c3k3")
+
+	o0 := otherContext{Background()}
+	check(o0, "o0", "", "", "")
+
+	o1 := otherContext{WithValue(Background(), k1, "c1k1")}
+	check(o1, "o1", "c1k1", "", "")
+
+	o2 := WithValue(o1, k2, "o2k2")
+	check(o2, "o2", "c1k1", "o2k2", "")
+
+	o3 := otherContext{c4}
+	check(o3, "o3", "", "c2k2", "c3k3")
+
+	o4 := WithValue(o3, k3, nil)
+	check(o4, "o4", "", "c2k2", "")
+}
+
+func TestAllocs(t *testing.T) {
+	bg := Background()
+	for _, test := range []struct {
+		desc       string
+		f          func()
+		limit      float64
+		gccgoLimit float64
+	}{
+		{
+			desc:       "Background()",
+			f:          func() { Background() },
+			limit:      0,
+			gccgoLimit: 0,
+		},
+		{
+			desc: fmt.Sprintf("WithValue(bg, %v, nil)", k1),
+			f: func() {
+				c := WithValue(bg, k1, nil)
+				c.Value(k1)
+			},
+			limit:      3,
+			gccgoLimit: 3,
+		},
+		{
+			desc: "WithTimeout(bg, 15*time.Millisecond)",
+			f: func() {
+				c, _ := WithTimeout(bg, 15*time.Millisecond)
+				<-c.Done()
+			},
+			limit:      8,
+			gccgoLimit: 15,
+		},
+		{
+			desc: "WithCancel(bg)",
+			f: func() {
+				c, cancel := WithCancel(bg)
+				cancel()
+				<-c.Done()
+			},
+			limit:      5,
+			gccgoLimit: 8,
+		},
+		{
+			desc: "WithTimeout(bg, 5*time.Millisecond)",
+			f: func() {
+				c, cancel := WithTimeout(bg, 5*time.Millisecond)
+				cancel()
+				<-c.Done()
+			},
+			limit:      8,
+			gccgoLimit: 25,
+		},
+	} {
+		limit := test.limit
+		if runtime.Compiler == "gccgo" {
+			// gccgo does not yet do escape analysis.
+			// TOOD(iant): Remove this when gccgo does do escape analysis.
+			limit = test.gccgoLimit
+		}
+		numRuns := 100
+		if testing.Short() {
+			numRuns = 10
+		}
+		if n := testing.AllocsPerRun(numRuns, test.f); n > limit {
+			t.Errorf("%s allocs = %f want %d", test.desc, n, int(limit))
+		}
+	}
+}
+
+func TestSimultaneousCancels(t *testing.T) {
+	root, cancel := WithCancel(Background())
+	m := map[Context]CancelFunc{root: cancel}
+	q := []Context{root}
+	// Create a tree of contexts.
+	for len(q) != 0 && len(m) < 100 {
+		parent := q[0]
+		q = q[1:]
+		for i := 0; i < 4; i++ {
+			ctx, cancel := WithCancel(parent)
+			m[ctx] = cancel
+			q = append(q, ctx)
+		}
+	}
+	// Start all the cancels in a random order.
+	var wg sync.WaitGroup
+	wg.Add(len(m))
+	for _, cancel := range m {
+		go func(cancel CancelFunc) {
+			cancel()
+			wg.Done()
+		}(cancel)
+	}
+	// Wait on all the contexts in a random order.
+	for ctx := range m {
+		select {
+		case <-ctx.Done():
+		case <-time.After(1 * time.Second):
+			buf := make([]byte, 10<<10)
+			n := runtime.Stack(buf, true)
+			t.Fatalf("timed out waiting for <-ctx.Done(); stacks:\n%s", buf[:n])
+		}
+	}
+	// Wait for all the cancel functions to return.
+	done := make(chan struct{})
+	go func() {
+		wg.Wait()
+		close(done)
+	}()
+	select {
+	case <-done:
+	case <-time.After(1 * time.Second):
+		buf := make([]byte, 10<<10)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("timed out waiting for cancel functions; stacks:\n%s", buf[:n])
+	}
+}
+
+func TestInterlockedCancels(t *testing.T) {
+	parent, cancelParent := WithCancel(Background())
+	child, cancelChild := WithCancel(parent)
+	go func() {
+		parent.Done()
+		cancelChild()
+	}()
+	cancelParent()
+	select {
+	case <-child.Done():
+	case <-time.After(1 * time.Second):
+		buf := make([]byte, 10<<10)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("timed out waiting for child.Done(); stacks:\n%s", buf[:n])
+	}
+}
+
+func TestLayersCancel(t *testing.T) {
+	testLayers(t, time.Now().UnixNano(), false)
+}
+
+func TestLayersTimeout(t *testing.T) {
+	testLayers(t, time.Now().UnixNano(), true)
+}
+
+func testLayers(t *testing.T, seed int64, testTimeout bool) {
+	rand.Seed(seed)
+	errorf := func(format string, a ...interface{}) {
+		t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
+	}
+	const (
+		timeout   = 200 * time.Millisecond
+		minLayers = 30
+	)
+	type value int
+	var (
+		vals      []*value
+		cancels   []CancelFunc
+		numTimers int
+		ctx       = Background()
+	)
+	for i := 0; i < minLayers || numTimers == 0 || len(cancels) == 0 || len(vals) == 0; i++ {
+		switch rand.Intn(3) {
+		case 0:
+			v := new(value)
+			ctx = WithValue(ctx, v, v)
+			vals = append(vals, v)
+		case 1:
+			var cancel CancelFunc
+			ctx, cancel = WithCancel(ctx)
+			cancels = append(cancels, cancel)
+		case 2:
+			var cancel CancelFunc
+			ctx, cancel = WithTimeout(ctx, timeout)
+			cancels = append(cancels, cancel)
+			numTimers++
+		}
+	}
+	checkValues := func(when string) {
+		for _, key := range vals {
+			if val := ctx.Value(key).(*value); key != val {
+				errorf("%s: ctx.Value(%p) = %p want %p", when, key, val, key)
+			}
+		}
+	}
+	select {
+	case <-ctx.Done():
+		errorf("ctx should not be canceled yet")
+	default:
+	}
+	if s, prefix := fmt.Sprint(ctx), "context.Background."; !strings.HasPrefix(s, prefix) {
+		t.Errorf("ctx.String() = %q want prefix %q", s, prefix)
+	}
+	t.Log(ctx)
+	checkValues("before cancel")
+	if testTimeout {
+		select {
+		case <-ctx.Done():
+		case <-time.After(timeout + time.Second):
+			errorf("ctx should have timed out")
+		}
+		checkValues("after timeout")
+	} else {
+		cancel := cancels[rand.Intn(len(cancels))]
+		cancel()
+		select {
+		case <-ctx.Done():
+		default:
+			errorf("ctx should be canceled")
+		}
+		checkValues("after cancel")
+	}
+}
+
+func TestCancelRemoves(t *testing.T) {
+	checkChildren := func(when string, ctx Context, want int) {
+		if got := len(ctx.(*cancelCtx).children); got != want {
+			t.Errorf("%s: context has %d children, want %d", when, got, want)
+		}
+	}
+
+	ctx, _ := WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	_, cancel := WithCancel(ctx)
+	checkChildren("with WithCancel child ", ctx, 1)
+	cancel()
+	checkChildren("after cancelling WithCancel child", ctx, 0)
+
+	ctx, _ = WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	_, cancel = WithTimeout(ctx, 60*time.Minute)
+	checkChildren("with WithTimeout child ", ctx, 1)
+	cancel()
+	checkChildren("after cancelling WithTimeout child", ctx, 0)
+}
+
+func TestWithValueChecksKey(t *testing.T) {
+	panicVal := recoveredValue(func() { WithValue(Background(), []byte("foo"), "bar") })
+	if panicVal == nil {
+		t.Error("expected panic")
+	}
+	panicVal = recoveredValue(func() { WithValue(Background(), nil, "bar") })
+	if got, want := fmt.Sprint(panicVal), "nil key"; got != want {
+		t.Errorf("panic = %q; want %q", got, want)
+	}
+}
+
+func recoveredValue(fn func()) (v interface{}) {
+	defer func() { v = recover() }()
+	fn()
+	return
+}
+
+func TestDeadlineExceededSupportsTimeout(t *testing.T) {
+	i, ok := DeadlineExceeded.(interface {
+		Timeout() bool
+	})
+	if !ok {
+		t.Fatal("DeadlineExceeded does not support Timeout interface")
+	}
+	if !i.Timeout() {
+		t.Fatal("wrong value for timeout")
+	}
+}
diff --git a/libgo/go/context/withtimeout_test.go b/libgo/go/context/withtimeout_test.go
new file mode 100644
index 00000000000..c74600b47b4
--- /dev/null
+++ b/libgo/go/context/withtimeout_test.go
@@ -0,0 +1,35 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package context_test
+
+import (
+	"context"
+	"fmt"
+	"time"
+)
+
+func ExampleWithTimeout() {
+	// Pass a context with a timeout to tell a blocking function that it
+	// should abandon its work after the timeout elapses.
+	ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
+
+	select {
+	case <-time.After(1 * time.Second):
+		fmt.Println("overslept")
+	case <-ctx.Done():
+		fmt.Println(ctx.Err()) // prints "context deadline exceeded"
+	}
+
+	// Even though ctx should have expired already, it is good
+	// practice to call its cancelation function in any case.
+	// Failure to do so may keep the context and its parent alive
+	// longer than necessary.
+	cancel()
+
+	// Output:
+	// context deadline exceeded
+}
diff --git a/libgo/go/crypto/aes/aes_gcm.go b/libgo/go/crypto/aes/aes_gcm.go
index 13775789509..a894a68293e 100644
--- a/libgo/go/crypto/aes/aes_gcm.go
+++ b/libgo/go/crypto/aes/aes_gcm.go
@@ -45,9 +45,12 @@ var errOpen = errors.New("cipher: message authentication failed")
 // will use the optimised implementation in this file when possible. Instances
 // of this type only exist when hasGCMAsm returns true.
 type aesCipherGCM struct {
-	aesCipher
+	aesCipherAsm
 }
 
+// Assert that aesCipherGCM implements the gcmAble interface.
+var _ gcmAble = (*aesCipherGCM)(nil)
+
 // NewGCM returns the AES cipher wrapped in Galois Counter Mode. This is only
 // called by crypto/cipher.NewGCM via the gcmAble interface.
 func (c *aesCipherGCM) NewGCM(nonceSize int) (cipher.AEAD, error) {
diff --git a/libgo/go/crypto/aes/aes_test.go b/libgo/go/crypto/aes/aes_test.go
index 363180931c7..28144968fcf 100644
--- a/libgo/go/crypto/aes/aes_test.go
+++ b/libgo/go/crypto/aes/aes_test.go
@@ -280,42 +280,6 @@ var encryptTests = []CryptTest{
 	},
 }
 
-// Test encryptBlock against FIPS 197 examples.
-func TestEncryptBlock(t *testing.T) {
-	for i, tt := range encryptTests {
-		n := len(tt.key) + 28
-		enc := make([]uint32, n)
-		dec := make([]uint32, n)
-		expandKey(tt.key, enc, dec)
-		out := make([]byte, len(tt.in))
-		encryptBlock(enc, out, tt.in)
-		for j, v := range out {
-			if v != tt.out[j] {
-				t.Errorf("encryptBlock %d: out[%d] = %#x, want %#x", i, j, v, tt.out[j])
-				break
-			}
-		}
-	}
-}
-
-// Test decryptBlock against FIPS 197 examples.
-func TestDecryptBlock(t *testing.T) {
-	for i, tt := range encryptTests {
-		n := len(tt.key) + 28
-		enc := make([]uint32, n)
-		dec := make([]uint32, n)
-		expandKey(tt.key, enc, dec)
-		plain := make([]byte, len(tt.in))
-		decryptBlock(dec, plain, tt.out)
-		for j, v := range plain {
-			if v != tt.in[j] {
-				t.Errorf("decryptBlock %d: plain[%d] = %#x, want %#x", i, j, v, tt.in[j])
-				break
-			}
-		}
-	}
-}
-
 // Test Cipher Encrypt method against FIPS 197 examples.
 func TestCipherEncrypt(t *testing.T) {
 	for i, tt := range encryptTests {
diff --git a/libgo/go/crypto/aes/block.go b/libgo/go/crypto/aes/block.go
index 57a7e9e25f2..41ea9cf95ed 100644
--- a/libgo/go/crypto/aes/block.go
+++ b/libgo/go/crypto/aes/block.go
@@ -137,7 +137,7 @@ func subw(w uint32) uint32 {
 // Rotate
 func rotw(w uint32) uint32 { return w<<8 | w>>24 }
 
-// Key expansion algorithm.  See FIPS-197, Figure 11.
+// Key expansion algorithm. See FIPS-197, Figure 11.
 // Their rcon[i] is our powx[i-1] << 24.
 func expandKeyGo(key []byte, enc, dec []uint32) {
 	// Encryption key setup.
diff --git a/libgo/go/crypto/aes/cbc_s390x.go b/libgo/go/crypto/aes/cbc_s390x.go
new file mode 100644
index 00000000000..427b30b2a70
--- /dev/null
+++ b/libgo/go/crypto/aes/cbc_s390x.go
@@ -0,0 +1,59 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package aes
+
+import (
+	"crypto/cipher"
+)
+
+// Assert that aesCipherAsm implements the cbcEncAble and cbcDecAble interfaces.
+var _ cbcEncAble = (*aesCipherAsm)(nil)
+var _ cbcDecAble = (*aesCipherAsm)(nil)
+
+type cbc struct {
+	b  *aesCipherAsm
+	c  code
+	iv [BlockSize]byte
+}
+
+func (b *aesCipherAsm) NewCBCEncrypter(iv []byte) cipher.BlockMode {
+	var c cbc
+	c.b = b
+	c.c = b.function
+	copy(c.iv[:], iv)
+	return &c
+}
+
+func (b *aesCipherAsm) NewCBCDecrypter(iv []byte) cipher.BlockMode {
+	var c cbc
+	c.b = b
+	c.c = b.function + 128 // decrypt function code is encrypt + 128
+	copy(c.iv[:], iv)
+	return &c
+}
+
+func (x *cbc) BlockSize() int { return BlockSize }
+
+// cryptBlocksChain invokes the cipher message with chaining (KMC) instruction
+// with the given function code. The length must be a multiple of BlockSize (16).
+//go:noescape
+func cryptBlocksChain(c code, iv, key, dst, src *byte, length int)
+
+func (x *cbc) CryptBlocks(dst, src []byte) {
+	if len(src)%BlockSize != 0 {
+		panic("crypto/cipher: input not full blocks")
+	}
+	if len(dst) < len(src) {
+		panic("crypto/cipher: output smaller than input")
+	}
+	cryptBlocksChain(x.c, &x.iv[0], &x.b.key[0], &dst[0], &src[0], len(src))
+}
+
+func (x *cbc) SetIV(iv []byte) {
+	if len(iv) != BlockSize {
+		panic("cipher: incorrect length IV")
+	}
+	copy(x.iv[:], iv)
+}
diff --git a/libgo/go/crypto/aes/cipher.go b/libgo/go/crypto/aes/cipher.go
index 04d2be1283f..c5a8e91d009 100644
--- a/libgo/go/crypto/aes/cipher.go
+++ b/libgo/go/crypto/aes/cipher.go
@@ -36,15 +36,15 @@ func NewCipher(key []byte) (cipher.Block, error) {
 	case 16, 24, 32:
 		break
 	}
+	return newCipher(key)
+}
 
-	n := k + 28
+// newCipherGeneric creates and returns a new cipher.Block
+// implemented in pure Go.
+func newCipherGeneric(key []byte) (cipher.Block, error) {
+	n := len(key) + 28
 	c := aesCipher{make([]uint32, n), make([]uint32, n)}
-	expandKey(key, c.enc, c.dec)
-
-	if hasGCMAsm() {
-		return &aesCipherGCM{c}, nil
-	}
-
+	expandKeyGo(key, c.enc, c.dec)
 	return &c, nil
 }
 
@@ -57,7 +57,7 @@ func (c *aesCipher) Encrypt(dst, src []byte) {
 	if len(dst) < BlockSize {
 		panic("crypto/aes: output not full block")
 	}
-	encryptBlock(c.enc, dst, src)
+	encryptBlockGo(c.enc, dst, src)
 }
 
 func (c *aesCipher) Decrypt(dst, src []byte) {
@@ -67,5 +67,5 @@ func (c *aesCipher) Decrypt(dst, src []byte) {
 	if len(dst) < BlockSize {
 		panic("crypto/aes: output not full block")
 	}
-	decryptBlock(c.dec, dst, src)
+	decryptBlockGo(c.dec, dst, src)
 }
diff --git a/libgo/go/crypto/aes/cipher_amd64.go b/libgo/go/crypto/aes/cipher_amd64.go
new file mode 100644
index 00000000000..b33c8ff251a
--- /dev/null
+++ b/libgo/go/crypto/aes/cipher_amd64.go
@@ -0,0 +1,83 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package aes
+
+import (
+	"crypto/cipher"
+)
+
+// defined in asm_amd64.s
+func hasAsm() bool
+func encryptBlockAsm(nr int, xk *uint32, dst, src *byte)
+func decryptBlockAsm(nr int, xk *uint32, dst, src *byte)
+func expandKeyAsm(nr int, key *byte, enc *uint32, dec *uint32)
+
+type aesCipherAsm struct {
+	aesCipher
+}
+
+var useAsm = hasAsm()
+
+func newCipher(key []byte) (cipher.Block, error) {
+	if !useAsm {
+		return newCipherGeneric(key)
+	}
+	n := len(key) + 28
+	c := aesCipherAsm{aesCipher{make([]uint32, n), make([]uint32, n)}}
+	rounds := 10
+	switch len(key) {
+	case 128 / 8:
+		rounds = 10
+	case 192 / 8:
+		rounds = 12
+	case 256 / 8:
+		rounds = 14
+	}
+	expandKeyAsm(rounds, &key[0], &c.enc[0], &c.dec[0])
+	if hasGCMAsm() {
+		return &aesCipherGCM{c}, nil
+	}
+
+	return &c, nil
+}
+
+func (c *aesCipherAsm) BlockSize() int { return BlockSize }
+
+func (c *aesCipherAsm) Encrypt(dst, src []byte) {
+	if len(src) < BlockSize {
+		panic("crypto/aes: input not full block")
+	}
+	if len(dst) < BlockSize {
+		panic("crypto/aes: output not full block")
+	}
+	encryptBlockAsm(len(c.enc)/4-1, &c.enc[0], &dst[0], &src[0])
+}
+
+func (c *aesCipherAsm) Decrypt(dst, src []byte) {
+	if len(src) < BlockSize {
+		panic("crypto/aes: input not full block")
+	}
+	if len(dst) < BlockSize {
+		panic("crypto/aes: output not full block")
+	}
+	decryptBlockAsm(len(c.dec)/4-1, &c.dec[0], &dst[0], &src[0])
+}
+
+// expandKey is used by BenchmarkExpand to ensure that the asm implementation
+// of key expansion is used for the benchmark when it is available.
+func expandKey(key []byte, enc, dec []uint32) {
+	if useAsm {
+		rounds := 10 // rounds needed for AES128
+		switch len(key) {
+		case 192 / 8:
+			rounds = 12
+		case 256 / 8:
+			rounds = 14
+		}
+		expandKeyAsm(rounds, &key[0], &enc[0], &dec[0])
+	} else {
+		expandKeyGo(key, enc, dec)
+	}
+}
diff --git a/libgo/go/crypto/aes/cipher_asm.go b/libgo/go/crypto/aes/cipher_asm.go
deleted file mode 100644
index 964eaaa6f88..00000000000
--- a/libgo/go/crypto/aes/cipher_asm.go
+++ /dev/null
@@ -1,48 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build amd64
-
-package aes
-
-// defined in asm_$GOARCH.s
-func hasAsm() bool
-func encryptBlockAsm(nr int, xk *uint32, dst, src *byte)
-func decryptBlockAsm(nr int, xk *uint32, dst, src *byte)
-func expandKeyAsm(nr int, key *byte, enc *uint32, dec *uint32)
-
-var useAsm = hasAsm()
-
-func encryptBlock(xk []uint32, dst, src []byte) {
-	if useAsm {
-		encryptBlockAsm(len(xk)/4-1, &xk[0], &dst[0], &src[0])
-	} else {
-		encryptBlockGo(xk, dst, src)
-	}
-}
-
-func decryptBlock(xk []uint32, dst, src []byte) {
-	if useAsm {
-		decryptBlockAsm(len(xk)/4-1, &xk[0], &dst[0], &src[0])
-	} else {
-		decryptBlockGo(xk, dst, src)
-	}
-}
-
-func expandKey(key []byte, enc, dec []uint32) {
-	if useAsm {
-		rounds := 10
-		switch len(key) {
-		case 128 / 8:
-			rounds = 10
-		case 192 / 8:
-			rounds = 12
-		case 256 / 8:
-			rounds = 14
-		}
-		expandKeyAsm(rounds, &key[0], &enc[0], &dec[0])
-	} else {
-		expandKeyGo(key, enc, dec)
-	}
-}
diff --git a/libgo/go/crypto/aes/cipher_generic.go b/libgo/go/crypto/aes/cipher_generic.go
index 32b2b3cc56d..f8070346e38 100644
--- a/libgo/go/crypto/aes/cipher_generic.go
+++ b/libgo/go/crypto/aes/cipher_generic.go
@@ -2,26 +2,25 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64
+// +build !amd64,!s390x
 
 package aes
 
-func encryptBlock(xk []uint32, dst, src []byte) {
-	encryptBlockGo(xk, dst, src)
-}
+import (
+	"crypto/cipher"
+)
 
-func decryptBlock(xk []uint32, dst, src []byte) {
-	decryptBlockGo(xk, dst, src)
+// newCipher calls the newCipherGeneric function
+// directly. Platforms with hardware accelerated
+// implementations of AES should implement their
+// own version of newCipher (which may then call
+// newCipherGeneric if needed).
+func newCipher(key []byte) (cipher.Block, error) {
+	return newCipherGeneric(key)
 }
 
+// expandKey is used by BenchmarkExpand and should
+// call an assembly implementation if one is available.
 func expandKey(key []byte, enc, dec []uint32) {
 	expandKeyGo(key, enc, dec)
 }
-
-func hasGCMAsm() bool {
-	return false
-}
-
-type aesCipherGCM struct {
-	aesCipher
-}
diff --git a/libgo/go/crypto/aes/cipher_s390x.go b/libgo/go/crypto/aes/cipher_s390x.go
new file mode 100644
index 00000000000..bec59330132
--- /dev/null
+++ b/libgo/go/crypto/aes/cipher_s390x.go
@@ -0,0 +1,90 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package aes
+
+import (
+	"crypto/cipher"
+)
+
+type code int
+
+// Function codes for the cipher message family of instructions.
+const (
+	aes128 code = 18
+	aes192      = 19
+	aes256      = 20
+)
+
+type aesCipherAsm struct {
+	function code      // code for cipher message instruction
+	key      []byte    // key (128, 192 or 256 bytes)
+	storage  [256]byte // array backing key slice
+}
+
+// hasAsm reports whether the AES-128, AES-192 and AES-256
+// cipher message (KM) function codes are supported.
+// Note: this function call is expensive.
+func hasAsm() bool
+
+// cryptBlocks invokes the cipher message (KM) instruction with
+// the given function code. This is equivalent to AES in ECB
+// mode. The length must be a multiple of BlockSize (16).
+//go:noesape
+func cryptBlocks(c code, key, dst, src *byte, length int)
+
+var useAsm = hasAsm()
+
+func newCipher(key []byte) (cipher.Block, error) {
+	if !useAsm {
+		return newCipherGeneric(key)
+	}
+
+	var function code
+	switch len(key) {
+	case 128 / 8:
+		function = aes128
+	case 192 / 8:
+		function = aes192
+	case 256 / 8:
+		function = aes256
+	default:
+		return nil, KeySizeError(len(key))
+	}
+
+	var c aesCipherAsm
+	c.function = function
+	c.key = c.storage[:len(key)]
+	copy(c.key, key)
+	return &c, nil
+}
+
+func (c *aesCipherAsm) BlockSize() int { return BlockSize }
+
+func (c *aesCipherAsm) Encrypt(dst, src []byte) {
+	if len(src) < BlockSize {
+		panic("crypto/aes: input not full block")
+	}
+	if len(dst) < BlockSize {
+		panic("crypto/aes: output not full block")
+	}
+	cryptBlocks(c.function, &c.key[0], &dst[0], &src[0], BlockSize)
+}
+
+func (c *aesCipherAsm) Decrypt(dst, src []byte) {
+	if len(src) < BlockSize {
+		panic("crypto/aes: input not full block")
+	}
+	if len(dst) < BlockSize {
+		panic("crypto/aes: output not full block")
+	}
+	// The decrypt function code is equal to the function code + 128.
+	cryptBlocks(c.function+128, &c.key[0], &dst[0], &src[0], BlockSize)
+}
+
+// expandKey is used by BenchmarkExpand. cipher message (KM) does not need key
+// expansion so there is no assembly equivalent.
+func expandKey(key []byte, enc, dec []uint32) {
+	expandKeyGo(key, enc, dec)
+}
diff --git a/libgo/go/crypto/aes/ctr_s390x.go b/libgo/go/crypto/aes/ctr_s390x.go
new file mode 100644
index 00000000000..94dea5ccdfe
--- /dev/null
+++ b/libgo/go/crypto/aes/ctr_s390x.go
@@ -0,0 +1,76 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package aes
+
+import (
+	"crypto/cipher"
+	"unsafe"
+)
+
+// Assert that aesCipherAsm implements the ctrAble interface.
+var _ ctrAble = (*aesCipherAsm)(nil)
+
+// xorBytes xors the contents of a and b and places the resulting values into
+// dst. If a and b are not the same length then the number of bytes processed
+// will be equal to the length of shorter of the two. Returns the number
+// of bytes processed.
+//go:noescape
+func xorBytes(dst, a, b []byte) int
+
+// streamBufferSize is the number of bytes of encrypted counter values to cache.
+const streamBufferSize = 32 * BlockSize
+
+type aesctr struct {
+	block   *aesCipherAsm          // block cipher
+	ctr     [2]uint64              // next value of the counter (big endian)
+	buffer  []byte                 // buffer for the encrypted counter values
+	storage [streamBufferSize]byte // array backing buffer slice
+}
+
+// NewCTR returns a Stream which encrypts/decrypts using the AES block
+// cipher in counter mode. The length of iv must be the same as BlockSize.
+func (c *aesCipherAsm) NewCTR(iv []byte) cipher.Stream {
+	if len(iv) != BlockSize {
+		panic("cipher.NewCTR: IV length must equal block size")
+	}
+	var ac aesctr
+	ac.block = c
+	ac.ctr[0] = *(*uint64)(unsafe.Pointer((&iv[0]))) // high bits
+	ac.ctr[1] = *(*uint64)(unsafe.Pointer((&iv[8]))) // low bits
+	ac.buffer = ac.storage[:0]
+	return &ac
+}
+
+func (c *aesctr) refill() {
+	// Fill up the buffer with an incrementing count.
+	c.buffer = c.storage[:streamBufferSize]
+	c0, c1 := c.ctr[0], c.ctr[1]
+	for i := 0; i < streamBufferSize; i += BlockSize {
+		b0 := (*uint64)(unsafe.Pointer(&c.buffer[i]))
+		b1 := (*uint64)(unsafe.Pointer(&c.buffer[i+BlockSize/2]))
+		*b0, *b1 = c0, c1
+		// Increment in big endian: c0 is high, c1 is low.
+		c1++
+		if c1 == 0 {
+			// add carry
+			c0++
+		}
+	}
+	c.ctr[0], c.ctr[1] = c0, c1
+	// Encrypt the buffer using AES in ECB mode.
+	cryptBlocks(c.block.function, &c.block.key[0], &c.buffer[0], &c.buffer[0], streamBufferSize)
+}
+
+func (c *aesctr) XORKeyStream(dst, src []byte) {
+	for len(src) > 0 {
+		if len(c.buffer) == 0 {
+			c.refill()
+		}
+		n := xorBytes(dst, src, c.buffer)
+		c.buffer = c.buffer[n:]
+		src = src[n:]
+		dst = dst[n:]
+	}
+}
diff --git a/libgo/go/crypto/aes/modes.go b/libgo/go/crypto/aes/modes.go
new file mode 100644
index 00000000000..1623fc16e22
--- /dev/null
+++ b/libgo/go/crypto/aes/modes.go
@@ -0,0 +1,37 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package aes
+
+import (
+	"crypto/cipher"
+)
+
+// gcmAble is implemented by cipher.Blocks that can provide an optimized
+// implementation of GCM through the AEAD interface.
+// See crypto/cipher/gcm.go.
+type gcmAble interface {
+	NewGCM(size int) (cipher.AEAD, error)
+}
+
+// cbcEncAble is implemented by cipher.Blocks that can provide an optimized
+// implementation of CBC encryption through the cipher.BlockMode interface.
+// See crypto/cipher/cbc.go.
+type cbcEncAble interface {
+	NewCBCEncrypter(iv []byte) cipher.BlockMode
+}
+
+// cbcDecAble is implemented by cipher.Blocks that can provide an optimized
+// implementation of CBC decryption through the cipher.BlockMode interface.
+// See crypto/cipher/cbc.go.
+type cbcDecAble interface {
+	NewCBCDecrypter(iv []byte) cipher.BlockMode
+}
+
+// ctrAble is implemented by cipher.Blocks that can provide an optimized
+// implementation of CTR through the cipher.Stream interface.
+// See crypto/cipher/ctr.go.
+type ctrAble interface {
+	NewCTR(iv []byte) cipher.Stream
+}
diff --git a/libgo/go/crypto/aes/modes_test.go b/libgo/go/crypto/aes/modes_test.go
new file mode 100644
index 00000000000..8c2e5f0560a
--- /dev/null
+++ b/libgo/go/crypto/aes/modes_test.go
@@ -0,0 +1,112 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package aes
+
+import (
+	"crypto/cipher"
+	"testing"
+)
+
+// Check that the optimized implementations of cipher modes will
+// be picked up correctly.
+
+// testInterface can be asserted to check that a type originates
+// from this test group.
+type testInterface interface {
+	InAESPackage() bool
+}
+
+// testBlock implements the cipher.Block interface and any *Able
+// interfaces that need to be tested.
+type testBlock struct{}
+
+func (*testBlock) BlockSize() int      { return 0 }
+func (*testBlock) Encrypt(a, b []byte) {}
+func (*testBlock) Decrypt(a, b []byte) {}
+func (*testBlock) NewGCM(int) (cipher.AEAD, error) {
+	return &testAEAD{}, nil
+}
+func (*testBlock) NewCBCEncrypter([]byte) cipher.BlockMode {
+	return &testBlockMode{}
+}
+func (*testBlock) NewCBCDecrypter([]byte) cipher.BlockMode {
+	return &testBlockMode{}
+}
+func (*testBlock) NewCTR([]byte) cipher.Stream {
+	return &testStream{}
+}
+
+// testAEAD implements the cipher.AEAD interface.
+type testAEAD struct{}
+
+func (*testAEAD) NonceSize() int                         { return 0 }
+func (*testAEAD) Overhead() int                          { return 0 }
+func (*testAEAD) Seal(a, b, c, d []byte) []byte          { return []byte{} }
+func (*testAEAD) Open(a, b, c, d []byte) ([]byte, error) { return []byte{}, nil }
+func (*testAEAD) InAESPackage() bool                     { return true }
+
+// Test the gcmAble interface is detected correctly by the cipher package.
+func TestGCMAble(t *testing.T) {
+	b := cipher.Block(&testBlock{})
+	if _, ok := b.(gcmAble); !ok {
+		t.Fatalf("testBlock does not implement the gcmAble interface")
+	}
+	aead, err := cipher.NewGCM(b)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	if _, ok := aead.(testInterface); !ok {
+		t.Fatalf("cipher.NewGCM did not use gcmAble interface")
+	}
+}
+
+// testBlockMode implements the cipher.BlockMode interface.
+type testBlockMode struct{}
+
+func (*testBlockMode) BlockSize() int          { return 0 }
+func (*testBlockMode) CryptBlocks(a, b []byte) {}
+func (*testBlockMode) InAESPackage() bool      { return true }
+
+// Test the cbcEncAble interface is detected correctly by the cipher package.
+func TestCBCEncAble(t *testing.T) {
+	b := cipher.Block(&testBlock{})
+	if _, ok := b.(cbcEncAble); !ok {
+		t.Fatalf("testBlock does not implement the cbcEncAble interface")
+	}
+	bm := cipher.NewCBCEncrypter(b, []byte{})
+	if _, ok := bm.(testInterface); !ok {
+		t.Fatalf("cipher.NewCBCEncrypter did not use cbcEncAble interface")
+	}
+}
+
+// Test the cbcDecAble interface is detected correctly by the cipher package.
+func TestCBCDecAble(t *testing.T) {
+	b := cipher.Block(&testBlock{})
+	if _, ok := b.(cbcDecAble); !ok {
+		t.Fatalf("testBlock does not implement the cbcDecAble interface")
+	}
+	bm := cipher.NewCBCDecrypter(b, []byte{})
+	if _, ok := bm.(testInterface); !ok {
+		t.Fatalf("cipher.NewCBCDecrypter did not use cbcDecAble interface")
+	}
+}
+
+// testStream implements the cipher.Stream interface.
+type testStream struct{}
+
+func (*testStream) XORKeyStream(a, b []byte) {}
+func (*testStream) InAESPackage() bool       { return true }
+
+// Test the ctrAble interface is detected correctly by the cipher package.
+func TestCTRAble(t *testing.T) {
+	b := cipher.Block(&testBlock{})
+	if _, ok := b.(ctrAble); !ok {
+		t.Fatalf("testBlock does not implement the ctrAble interface")
+	}
+	s := cipher.NewCTR(b, []byte{})
+	if _, ok := s.(testInterface); !ok {
+		t.Fatalf("cipher.NewCTR did not use ctrAble interface")
+	}
+}
diff --git a/libgo/go/crypto/cipher/cbc.go b/libgo/go/crypto/cipher/cbc.go
index 241e122ee80..0367d5971a6 100644
--- a/libgo/go/crypto/cipher/cbc.go
+++ b/libgo/go/crypto/cipher/cbc.go
@@ -29,6 +29,14 @@ func newCBC(b Block, iv []byte) *cbc {
 
 type cbcEncrypter cbc
 
+// cbcEncAble is an interface implemented by ciphers that have a specific
+// optimized implementation of CBC encryption, like crypto/aes.
+// NewCBCEncrypter will check for this interface and return the specific
+// BlockMode if found.
+type cbcEncAble interface {
+	NewCBCEncrypter(iv []byte) BlockMode
+}
+
 // NewCBCEncrypter returns a BlockMode which encrypts in cipher block chaining
 // mode, using the given Block. The length of iv must be the same as the
 // Block's block size.
@@ -36,6 +44,9 @@ func NewCBCEncrypter(b Block, iv []byte) BlockMode {
 	if len(iv) != b.BlockSize() {
 		panic("cipher.NewCBCEncrypter: IV length must equal block size")
 	}
+	if cbc, ok := b.(cbcEncAble); ok {
+		return cbc.NewCBCEncrypter(iv)
+	}
 	return (*cbcEncrypter)(newCBC(b, iv))
 }
 
@@ -75,6 +86,14 @@ func (x *cbcEncrypter) SetIV(iv []byte) {
 
 type cbcDecrypter cbc
 
+// cbcDecAble is an interface implemented by ciphers that have a specific
+// optimized implementation of CBC decryption, like crypto/aes.
+// NewCBCDecrypter will check for this interface and return the specific
+// BlockMode if found.
+type cbcDecAble interface {
+	NewCBCDecrypter(iv []byte) BlockMode
+}
+
 // NewCBCDecrypter returns a BlockMode which decrypts in cipher block chaining
 // mode, using the given Block. The length of iv must be the same as the
 // Block's block size and must match the iv used to encrypt the data.
@@ -82,6 +101,9 @@ func NewCBCDecrypter(b Block, iv []byte) BlockMode {
 	if len(iv) != b.BlockSize() {
 		panic("cipher.NewCBCDecrypter: IV length must equal block size")
 	}
+	if cbc, ok := b.(cbcDecAble); ok {
+		return cbc.NewCBCDecrypter(iv)
+	}
 	return (*cbcDecrypter)(newCBC(b, iv))
 }
 
diff --git a/libgo/go/crypto/cipher/cipher.go b/libgo/go/crypto/cipher/cipher.go
index 7d27fde61d8..531ecad9ac0 100644
--- a/libgo/go/crypto/cipher/cipher.go
+++ b/libgo/go/crypto/cipher/cipher.go
@@ -9,8 +9,8 @@
 package cipher
 
 // A Block represents an implementation of block cipher
-// using a given key.  It provides the capability to encrypt
-// or decrypt individual blocks.  The mode implementations
+// using a given key. It provides the capability to encrypt
+// or decrypt individual blocks. The mode implementations
 // extend that capability to streams of blocks.
 type Block interface {
 	// BlockSize returns the cipher's block size.
diff --git a/libgo/go/crypto/cipher/cipher_test.go b/libgo/go/crypto/cipher/cipher_test.go
index 8da5bce93ff..1faa7b87e52 100644
--- a/libgo/go/crypto/cipher/cipher_test.go
+++ b/libgo/go/crypto/cipher/cipher_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/cipher/ctr.go b/libgo/go/crypto/cipher/ctr.go
index 16baa6d17d0..75f46cfe512 100644
--- a/libgo/go/crypto/cipher/ctr.go
+++ b/libgo/go/crypto/cipher/ctr.go
@@ -21,9 +21,19 @@ type ctr struct {
 
 const streamBufferSize = 512
 
+// ctrAble is an interface implemented by ciphers that have a specific optimized
+// implementation of CTR, like crypto/aes. NewCTR will check for this interface
+// and return the specific Stream if found.
+type ctrAble interface {
+	NewCTR(iv []byte) Stream
+}
+
 // NewCTR returns a Stream which encrypts/decrypts using the given Block in
 // counter mode. The length of iv must be the same as the Block's block size.
 func NewCTR(block Block, iv []byte) Stream {
+	if ctr, ok := block.(ctrAble); ok {
+		return ctr.NewCTR(iv)
+	}
 	if len(iv) != block.BlockSize() {
 		panic("cipher.NewCTR: IV length must equal block size")
 	}
diff --git a/libgo/go/crypto/cipher/example_test.go b/libgo/go/crypto/cipher/example_test.go
index f6cc3865061..9abe782bca5 100644
--- a/libgo/go/crypto/cipher/example_test.go
+++ b/libgo/go/crypto/cipher/example_test.go
@@ -44,9 +44,9 @@ func ExampleNewGCMDecrypter() {
 	// The key argument should be the AES key, either 16 or 32 bytes
 	// to select AES-128 or AES-256.
 	key := []byte("AES256Key-32Characters1234567890")
-	ciphertext, _ := hex.DecodeString("f90fbef747e7212ad7410d0eee2d965de7e890471695cddd2a5bc0ef5da1d04ad8147b62141ad6e4914aee8c512f64fba9037603d41de0d50b718bd665f019cdcd")
+	ciphertext, _ := hex.DecodeString("1019aa66cd7c024f9efd0038899dae1973ee69427f5a6579eba292ffe1b5a260")
 
-	nonce, _ := hex.DecodeString("bb8ef84243d2ee95a41c6c57")
+	nonce, _ := hex.DecodeString("37b8e8a308c354048d245f6d")
 
 	block, err := aes.NewCipher(key)
 	if err != nil {
@@ -63,7 +63,8 @@ func ExampleNewGCMDecrypter() {
 		panic(err.Error())
 	}
 
-	fmt.Printf("%s\n", string(plaintext))
+	fmt.Printf("%s\n", plaintext)
+	// Output: exampleplaintext
 }
 
 func ExampleNewCBCDecrypter() {
diff --git a/libgo/go/crypto/cipher/xor.go b/libgo/go/crypto/cipher/xor.go
index f88dc8914ac..01ca0a9f086 100644
--- a/libgo/go/crypto/cipher/xor.go
+++ b/libgo/go/crypto/cipher/xor.go
@@ -10,7 +10,7 @@ import (
 )
 
 const wordSize = int(unsafe.Sizeof(uintptr(0)))
-const supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64"
+const supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64" || runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "s390x"
 
 // fastXORBytes xors in bulk. It only works on architectures that
 // support unaligned read/writes.
diff --git a/libgo/go/crypto/cipher/xor_test.go b/libgo/go/crypto/cipher/xor_test.go
index cc1c9d72d55..d9187eb7263 100644
--- a/libgo/go/crypto/cipher/xor_test.go
+++ b/libgo/go/crypto/cipher/xor_test.go
@@ -19,7 +19,7 @@ func TestXOR(t *testing.T) {
 				d2 := make([]byte, 1024+alignD)[alignD:]
 				xorBytes(d1, p, q)
 				safeXORBytes(d2, p, q)
-				if bytes.Compare(d1, d2) != 0 {
+				if !bytes.Equal(d1, d2) {
 					t.Error("not equal")
 				}
 			}
diff --git a/libgo/go/crypto/des/block.go b/libgo/go/crypto/des/block.go
index 26355a22e71..99338d62a6e 100644
--- a/libgo/go/crypto/des/block.go
+++ b/libgo/go/crypto/des/block.go
@@ -72,7 +72,7 @@ func init() {
 		for i := 0; i < 4; i++ {
 			for j := 0; j < 16; j++ {
 				f := uint64(sBoxes[s][i][j]) << (4 * (7 - uint(s)))
-				f = permuteBlock(uint64(f), permutationFunction[:])
+				f = permuteBlock(f, permutationFunction[:])
 				feistelBox[s][16*i+j] = uint32(f)
 			}
 		}
diff --git a/libgo/go/crypto/dsa/dsa.go b/libgo/go/crypto/dsa/dsa.go
index 9f414a470c7..e9b6a0c2532 100644
--- a/libgo/go/crypto/dsa/dsa.go
+++ b/libgo/go/crypto/dsa/dsa.go
@@ -52,7 +52,7 @@ const numMRTests = 64
 
 // GenerateParameters puts a random, valid set of DSA parameters into params.
 // This function can take many seconds, even on fast machines.
-func GenerateParameters(params *Parameters, rand io.Reader, sizes ParameterSizes) (err error) {
+func GenerateParameters(params *Parameters, rand io.Reader, sizes ParameterSizes) error {
 	// This function doesn't follow FIPS 186-3 exactly in that it doesn't
 	// use a verification seed to generate the primes. The verification
 	// seed doesn't appear to be exported or used by other code and
@@ -87,9 +87,8 @@ func GenerateParameters(params *Parameters, rand io.Reader, sizes ParameterSizes
 
 GeneratePrimes:
 	for {
-		_, err = io.ReadFull(rand, qBytes)
-		if err != nil {
-			return
+		if _, err := io.ReadFull(rand, qBytes); err != nil {
+			return err
 		}
 
 		qBytes[len(qBytes)-1] |= 1
@@ -101,9 +100,8 @@ GeneratePrimes:
 		}
 
 		for i := 0; i < 4*L; i++ {
-			_, err = io.ReadFull(rand, pBytes)
-			if err != nil {
-				return
+			if _, err := io.ReadFull(rand, pBytes); err != nil {
+				return err
 			}
 
 			pBytes[len(pBytes)-1] |= 1
@@ -142,7 +140,7 @@ GeneratePrimes:
 		}
 
 		params.G = g
-		return
+		return nil
 	}
 }
 
diff --git a/libgo/go/crypto/ecdsa/ecdsa.go b/libgo/go/crypto/ecdsa/ecdsa.go
index e54488c9cf6..72fb49934fc 100644
--- a/libgo/go/crypto/ecdsa/ecdsa.go
+++ b/libgo/go/crypto/ecdsa/ecdsa.go
@@ -97,17 +97,17 @@ func randFieldElement(c elliptic.Curve, rand io.Reader) (k *big.Int, err error)
 }
 
 // GenerateKey generates a public and private key pair.
-func GenerateKey(c elliptic.Curve, rand io.Reader) (priv *PrivateKey, err error) {
+func GenerateKey(c elliptic.Curve, rand io.Reader) (*PrivateKey, error) {
 	k, err := randFieldElement(c, rand)
 	if err != nil {
-		return
+		return nil, err
 	}
 
-	priv = new(PrivateKey)
+	priv := new(PrivateKey)
 	priv.PublicKey.Curve = c
 	priv.D = k
 	priv.PublicKey.X, priv.PublicKey.Y = c.ScalarBaseMult(k.Bytes())
-	return
+	return priv, nil
 }
 
 // hashToInt converts a hash value to an integer. There is some disagreement
@@ -143,10 +143,11 @@ func fermatInverse(k, N *big.Int) *big.Int {
 
 var errZeroParam = errors.New("zero parameter")
 
-// Sign signs an arbitrary length hash (which should be the result of hashing a
-// larger message) using the private key, priv. It returns the signature as a
-// pair of integers. The security of the private key depends on the entropy of
-// rand.
+// Sign signs a hash (which should be the result of hashing a larger message)
+// using the private key, priv. If the hash is longer than the bit-length of the
+// private key's curve order, the hash will be truncated to that length.  It
+// returns the signature as a pair of integers. The security of the private key
+// depends on the entropy of rand.
 func Sign(rand io.Reader, priv *PrivateKey, hash []byte) (r, s *big.Int, err error) {
 	// Get max(log2(q) / 2, 256) bits of entropy from rand.
 	entropylen := (priv.Curve.Params().BitSize + 7) / 16
@@ -228,7 +229,7 @@ func Verify(pub *PublicKey, hash []byte, r, s *big.Int) bool {
 	c := pub.Curve
 	N := c.Params().N
 
-	if r.Sign() == 0 || s.Sign() == 0 {
+	if r.Sign() <= 0 || s.Sign() <= 0 {
 		return false
 	}
 	if r.Cmp(N) >= 0 || s.Cmp(N) >= 0 {
diff --git a/libgo/go/crypto/ecdsa/ecdsa_test.go b/libgo/go/crypto/ecdsa/ecdsa_test.go
index 62a3fcc4964..fc25fd74a78 100644
--- a/libgo/go/crypto/ecdsa/ecdsa_test.go
+++ b/libgo/go/crypto/ecdsa/ecdsa_test.go
@@ -130,7 +130,7 @@ func testNonceSafety(t *testing.T, c elliptic.Curve, tag string) {
 	}
 
 	if r0.Cmp(r1) == 0 {
-		t.Errorf("%s: the nonce used for two diferent messages was the same", tag)
+		t.Errorf("%s: the nonce used for two different messages was the same", tag)
 	}
 }
 
@@ -296,3 +296,26 @@ func TestVectors(t *testing.T) {
 		}
 	}
 }
+
+func testNegativeInputs(t *testing.T, curve elliptic.Curve, tag string) {
+	key, err := GenerateKey(curve, rand.Reader)
+	if err != nil {
+		t.Errorf("failed to generate key for %q", tag)
+	}
+
+	var hash [32]byte
+	r := new(big.Int).SetInt64(1)
+	r.Lsh(r, 550 /* larger than any supported curve */)
+	r.Neg(r)
+
+	if Verify(&key.PublicKey, hash[:], r, r) {
+		t.Errorf("bogus signature accepted for %q", tag)
+	}
+}
+
+func TestNegativeInputs(t *testing.T) {
+	testNegativeInputs(t, elliptic.P224(), "p224")
+	testNegativeInputs(t, elliptic.P256(), "p256")
+	testNegativeInputs(t, elliptic.P384(), "p384")
+	testNegativeInputs(t, elliptic.P521(), "p521")
+}
diff --git a/libgo/go/crypto/elliptic/p224.go b/libgo/go/crypto/elliptic/p224.go
index 2d3fac74fbf..de266ca77a7 100644
--- a/libgo/go/crypto/elliptic/p224.go
+++ b/libgo/go/crypto/elliptic/p224.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/elliptic/p224_test.go b/libgo/go/crypto/elliptic/p224_test.go
index 4b26d1610ed..8b4fa0483b6 100644
--- a/libgo/go/crypto/elliptic/p224_test.go
+++ b/libgo/go/crypto/elliptic/p224_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/elliptic/p256.go b/libgo/go/crypto/elliptic/p256.go
index 5103e86de9e..05a3311b290 100644
--- a/libgo/go/crypto/elliptic/p256.go
+++ b/libgo/go/crypto/elliptic/p256.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -1056,7 +1056,7 @@ func p256ScalarBaseMult(xOut, yOut, zOut *[p256Limbs]uint32, scalar *[32]uint8)
 			p256CopyConditional(yOut, &ty, mask)
 			p256CopyConditional(zOut, &tz, mask)
 			// If p was not zero, then n is now non-zero.
-			nIsInfinityMask &= ^pIsNoninfiniteMask
+			nIsInfinityMask &^= pIsNoninfiniteMask
 		}
 	}
 }
@@ -1136,7 +1136,7 @@ func p256ScalarMult(xOut, yOut, zOut, x, y *[p256Limbs]uint32, scalar *[32]uint8
 		p256CopyConditional(xOut, &tx, mask)
 		p256CopyConditional(yOut, &ty, mask)
 		p256CopyConditional(zOut, &tz, mask)
-		nIsInfinityMask &= ^pIsNoninfiniteMask
+		nIsInfinityMask &^= pIsNoninfiniteMask
 	}
 }
 
diff --git a/libgo/go/crypto/elliptic/p256_amd64.go b/libgo/go/crypto/elliptic/p256_amd64.go
index 586cd10c4f6..66b7cf8dc51 100644
--- a/libgo/go/crypto/elliptic/p256_amd64.go
+++ b/libgo/go/crypto/elliptic/p256_amd64.go
@@ -66,7 +66,7 @@ func p256NegCond(val []uint64, cond int)
 // if cond == 0 res <- b; else res <- a
 func p256MovCond(res, a, b []uint64, cond int)
 
-// Endianess swap
+// Endianness swap
 func p256BigToLittle(res []uint64, in []byte)
 func p256LittleToBig(res []byte, in []uint64)
 
@@ -93,10 +93,14 @@ func p256PointAddAsm(res, in1, in2 []uint64)
 func p256PointDoubleAsm(res, in []uint64)
 
 func (curve p256Curve) Inverse(k *big.Int) *big.Int {
+	if k.Sign() < 0 {
+		// This should never happen.
+		k = new(big.Int).Neg(k)
+	}
+
 	if k.Cmp(p256.N) >= 0 {
 		// This should never happen.
-		reducedK := new(big.Int).Mod(k, p256.N)
-		k = reducedK
+		k = new(big.Int).Mod(k, p256.N)
 	}
 
 	// table will store precomputed powers of x. The four words at index
diff --git a/libgo/go/crypto/hmac/hmac.go b/libgo/go/crypto/hmac/hmac.go
index 3b41cde0bd5..a7481078388 100644
--- a/libgo/go/crypto/hmac/hmac.go
+++ b/libgo/go/crypto/hmac/hmac.go
@@ -37,26 +37,16 @@ import (
 type hmac struct {
 	size         int
 	blocksize    int
-	key, tmp     []byte
+	opad, ipad   []byte
 	outer, inner hash.Hash
 }
 
-func (h *hmac) tmpPad(xor byte) {
-	for i, k := range h.key {
-		h.tmp[i] = xor ^ k
-	}
-	for i := len(h.key); i < h.blocksize; i++ {
-		h.tmp[i] = xor
-	}
-}
-
 func (h *hmac) Sum(in []byte) []byte {
 	origLen := len(in)
 	in = h.inner.Sum(in)
-	h.tmpPad(0x5c)
-	copy(h.tmp[h.blocksize:], in[origLen:])
 	h.outer.Reset()
-	h.outer.Write(h.tmp)
+	h.outer.Write(h.opad)
+	h.outer.Write(in[origLen:])
 	return h.outer.Sum(in[:origLen])
 }
 
@@ -70,8 +60,7 @@ func (h *hmac) BlockSize() int { return h.blocksize }
 
 func (h *hmac) Reset() {
 	h.inner.Reset()
-	h.tmpPad(0x36)
-	h.inner.Write(h.tmp[:h.blocksize])
+	h.inner.Write(h.ipad)
 }
 
 // New returns a new HMAC hash using the given hash.Hash type and key.
@@ -81,15 +70,22 @@ func New(h func() hash.Hash, key []byte) hash.Hash {
 	hm.inner = h()
 	hm.size = hm.inner.Size()
 	hm.blocksize = hm.inner.BlockSize()
-	hm.tmp = make([]byte, hm.blocksize+hm.size)
+	hm.ipad = make([]byte, hm.blocksize)
+	hm.opad = make([]byte, hm.blocksize)
 	if len(key) > hm.blocksize {
 		// If key is too big, hash it.
 		hm.outer.Write(key)
 		key = hm.outer.Sum(nil)
 	}
-	hm.key = make([]byte, len(key))
-	copy(hm.key, key)
-	hm.Reset()
+	copy(hm.ipad, key)
+	copy(hm.opad, key)
+	for i := range hm.ipad {
+		hm.ipad[i] ^= 0x36
+	}
+	for i := range hm.opad {
+		hm.opad[i] ^= 0x5c
+	}
+	hm.inner.Write(hm.ipad)
 	return hm
 }
 
diff --git a/libgo/go/crypto/hmac/hmac_test.go b/libgo/go/crypto/hmac/hmac_test.go
index e80b7e0baa0..aac9aa96a8e 100644
--- a/libgo/go/crypto/hmac/hmac_test.go
+++ b/libgo/go/crypto/hmac/hmac_test.go
@@ -568,3 +568,29 @@ func TestEqual(t *testing.T) {
 		t.Error("Equal accepted unequal slices")
 	}
 }
+
+func BenchmarkHMACSHA256_1K(b *testing.B) {
+	key := make([]byte, 32)
+	buf := make([]byte, 1024)
+	h := New(sha256.New, key)
+	b.SetBytes(int64(len(buf)))
+	for i := 0; i < b.N; i++ {
+		h.Write(buf)
+		h.Reset()
+		mac := h.Sum(nil)
+		buf[0] = mac[0]
+	}
+}
+
+func BenchmarkHMACSHA256_32(b *testing.B) {
+	key := make([]byte, 32)
+	buf := make([]byte, 32)
+	h := New(sha256.New, key)
+	b.SetBytes(int64(len(buf)))
+	for i := 0; i < b.N; i++ {
+		h.Write(buf)
+		h.Reset()
+		mac := h.Sum(nil)
+		buf[0] = mac[0]
+	}
+}
diff --git a/libgo/go/crypto/md5/gen.go b/libgo/go/crypto/md5/gen.go
index 8cd0a6358e1..178fad18285 100644
--- a/libgo/go/crypto/md5/gen.go
+++ b/libgo/go/crypto/md5/gen.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/md5/md5.go b/libgo/go/crypto/md5/md5.go
index a3550cb7dda..ce58d5e713a 100644
--- a/libgo/go/crypto/md5/md5.go
+++ b/libgo/go/crypto/md5/md5.go
@@ -89,7 +89,7 @@ func (d0 *digest) Sum(in []byte) []byte {
 }
 
 func (d *digest) checkSum() [Size]byte {
-	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
+	// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
 	len := d.len
 	var tmp [64]byte
 	tmp[0] = 0x80
diff --git a/libgo/go/crypto/md5/md5block_decl.go b/libgo/go/crypto/md5/md5block_decl.go
index d7956a6d203..1e6f6e60544 100644
--- a/libgo/go/crypto/md5/md5block_decl.go
+++ b/libgo/go/crypto/md5/md5block_decl.go
@@ -1,8 +1,8 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64 amd64p32 386 arm
+// +build amd64 amd64p32 386 arm ppc64le s390x
 
 package md5
 
diff --git a/libgo/go/crypto/md5/md5block_generic.go b/libgo/go/crypto/md5/md5block_generic.go
index 263463e51cd..726e09b985c 100644
--- a/libgo/go/crypto/md5/md5block_generic.go
+++ b/libgo/go/crypto/md5/md5block_generic.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64,!amd64p32,!386,!arm
+// +build !amd64,!amd64p32,!386,!arm,!ppc64le,!s390x
 
 package md5
 
diff --git a/libgo/go/crypto/rand/eagain.go b/libgo/go/crypto/rand/eagain.go
index 2c853d0a134..7ed2f47ea66 100644
--- a/libgo/go/crypto/rand/eagain.go
+++ b/libgo/go/crypto/rand/eagain.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/rand/rand.go b/libgo/go/crypto/rand/rand.go
index ee32fa0bd67..6f7523d9d73 100644
--- a/libgo/go/crypto/rand/rand.go
+++ b/libgo/go/crypto/rand/rand.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -11,8 +11,9 @@ import "io"
 // Reader is a global, shared instance of a cryptographically
 // strong pseudo-random generator.
 //
-// On Unix-like systems, Reader reads from /dev/urandom.
 // On Linux, Reader uses getrandom(2) if available, /dev/urandom otherwise.
+// On OpenBSD, Reader uses getentropy(2).
+// On other Unix-like systems, Reader reads from /dev/urandom.
 // On Windows systems, Reader uses the CryptGenRandom API.
 var Reader io.Reader
 
diff --git a/libgo/go/crypto/rand/rand_linux.go b/libgo/go/crypto/rand/rand_linux.go
index 7d6d9e8a094..472daa7650b 100644
--- a/libgo/go/crypto/rand/rand_linux.go
+++ b/libgo/go/crypto/rand/rand_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/rand/rand_openbsd.go b/libgo/go/crypto/rand/rand_openbsd.go
new file mode 100644
index 00000000000..9cc39f72d1d
--- /dev/null
+++ b/libgo/go/crypto/rand/rand_openbsd.go
@@ -0,0 +1,28 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package rand
+
+import (
+	"internal/syscall/unix"
+)
+
+func init() {
+	altGetRandom = getRandomOpenBSD
+}
+
+func getRandomOpenBSD(p []byte) (ok bool) {
+	// getentropy(2) returns a maximum of 256 bytes per call
+	for i := 0; i < len(p); i += 256 {
+		end := i + 256
+		if len(p) < end {
+			end = len(p)
+		}
+		err := unix.GetEntropy(p[i:end])
+		if err != nil {
+			return false
+		}
+	}
+	return true
+}
diff --git a/libgo/go/crypto/rand/rand_test.go b/libgo/go/crypto/rand/rand_test.go
index e46e61d374a..e45f58e4e7a 100644
--- a/libgo/go/crypto/rand/rand_test.go
+++ b/libgo/go/crypto/rand/rand_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/rand/rand_unix.go b/libgo/go/crypto/rand/rand_unix.go
index 75c36e05b34..631972b92ac 100644
--- a/libgo/go/crypto/rand/rand_unix.go
+++ b/libgo/go/crypto/rand/rand_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -84,7 +84,7 @@ func (hr hideAgainReader) Read(p []byte) (n int, err error) {
 // systems without a reliable /dev/urandom.
 
 // newReader returns a new pseudorandom generator that
-// seeds itself by reading from entropy.  If entropy == nil,
+// seeds itself by reading from entropy. If entropy == nil,
 // the generator seeds itself by reading from the system's
 // random number generator, typically /dev/random.
 // The Read method on the returned reader always returns
diff --git a/libgo/go/crypto/rand/rand_windows.go b/libgo/go/crypto/rand/rand_windows.go
index 82b39b64a3c..4d7511a8400 100644
--- a/libgo/go/crypto/rand/rand_windows.go
+++ b/libgo/go/crypto/rand/rand_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/rand/util.go b/libgo/go/crypto/rand/util.go
index 5f74407850c..592c57e7638 100644
--- a/libgo/go/crypto/rand/util.go
+++ b/libgo/go/crypto/rand/util.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -70,7 +70,7 @@ func Prime(rand io.Reader, bits int) (p *big.Int, err error) {
 
 		p.SetBytes(bytes)
 
-		// Calculate the value mod the product of smallPrimes.  If it's
+		// Calculate the value mod the product of smallPrimes. If it's
 		// a multiple of any of these primes we add two until it isn't.
 		// The probability of overflowing is minimal and can be ignored
 		// because we still perform Miller-Rabin tests on the result.
diff --git a/libgo/go/crypto/rand/util_test.go b/libgo/go/crypto/rand/util_test.go
index 2f7cba8364a..7b076896767 100644
--- a/libgo/go/crypto/rand/util_test.go
+++ b/libgo/go/crypto/rand/util_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/crypto/rc4/rc4.go b/libgo/go/crypto/rc4/rc4.go
index 9acb681bfb6..bd04aee6955 100644
--- a/libgo/go/crypto/rc4/rc4.go
+++ b/libgo/go/crypto/rc4/rc4.go
@@ -23,7 +23,7 @@ func (k KeySizeError) Error() string {
 	return "crypto/rc4: invalid key size " + strconv.Itoa(int(k))
 }
 
-// NewCipher creates and returns a new Cipher.  The key argument should be the
+// NewCipher creates and returns a new Cipher. The key argument should be the
 // RC4 key, at least 1 byte and at most 256 bytes.
 func NewCipher(key []byte) (*Cipher, error) {
 	k := len(key)
@@ -52,7 +52,7 @@ func (c *Cipher) Reset() {
 }
 
 // xorKeyStreamGeneric sets dst to the result of XORing src with the
-// key stream.  Dst and src may be the same slice but otherwise should
+// key stream. Dst and src may be the same slice but otherwise should
 // not overlap.
 //
 // This is the pure Go version. rc4_{amd64,386,arm}* contain assembly
diff --git a/libgo/go/crypto/rsa/pkcs1v15.go b/libgo/go/crypto/rsa/pkcs1v15.go
index 5c5f415c88d..3517a8c776c 100644
--- a/libgo/go/crypto/rsa/pkcs1v15.go
+++ b/libgo/go/crypto/rsa/pkcs1v15.go
@@ -24,31 +24,32 @@ type PKCS1v15DecryptOptions struct {
 	SessionKeyLen int
 }
 
-// EncryptPKCS1v15 encrypts the given message with RSA and the padding scheme from PKCS#1 v1.5.
-// The message must be no longer than the length of the public modulus minus 11 bytes.
+// EncryptPKCS1v15 encrypts the given message with RSA and the padding
+// scheme from PKCS#1 v1.5.  The message must be no longer than the
+// length of the public modulus minus 11 bytes.
 //
-// The rand parameter is used as a source of entropy to ensure that encrypting
-// the same message twice doesn't result in the same ciphertext.
+// The rand parameter is used as a source of entropy to ensure that
+// encrypting the same message twice doesn't result in the same
+// ciphertext.
 //
-// WARNING: use of this function to encrypt plaintexts other than session keys
-// is dangerous. Use RSA OAEP in new protocols.
-func EncryptPKCS1v15(rand io.Reader, pub *PublicKey, msg []byte) (out []byte, err error) {
+// WARNING: use of this function to encrypt plaintexts other than
+// session keys is dangerous. Use RSA OAEP in new protocols.
+func EncryptPKCS1v15(rand io.Reader, pub *PublicKey, msg []byte) ([]byte, error) {
 	if err := checkPub(pub); err != nil {
 		return nil, err
 	}
 	k := (pub.N.BitLen() + 7) / 8
 	if len(msg) > k-11 {
-		err = ErrMessageTooLong
-		return
+		return nil, ErrMessageTooLong
 	}
 
 	// EM = 0x00 || 0x02 || PS || 0x00 || M
 	em := make([]byte, k)
 	em[1] = 2
 	ps, mm := em[2:len(em)-len(msg)-1], em[len(em)-len(msg):]
-	err = nonZeroRandomBytes(ps, rand)
+	err := nonZeroRandomBytes(ps, rand)
 	if err != nil {
-		return
+		return nil, err
 	}
 	em[len(em)-len(msg)-1] = 0
 	copy(mm, msg)
@@ -57,8 +58,7 @@ func EncryptPKCS1v15(rand io.Reader, pub *PublicKey, msg []byte) (out []byte, er
 	c := encrypt(new(big.Int), pub, m)
 
 	copyWithLeftPad(em, c.Bytes())
-	out = em
-	return
+	return em, nil
 }
 
 // DecryptPKCS1v15 decrypts a plaintext using RSA and the padding scheme from PKCS#1 v1.5.
@@ -69,19 +69,18 @@ func EncryptPKCS1v15(rand io.Reader, pub *PublicKey, msg []byte) (out []byte, er
 // learn whether each instance returned an error then they can decrypt and
 // forge signatures as if they had the private key. See
 // DecryptPKCS1v15SessionKey for a way of solving this problem.
-func DecryptPKCS1v15(rand io.Reader, priv *PrivateKey, ciphertext []byte) (out []byte, err error) {
+func DecryptPKCS1v15(rand io.Reader, priv *PrivateKey, ciphertext []byte) ([]byte, error) {
 	if err := checkPub(&priv.PublicKey); err != nil {
 		return nil, err
 	}
 	valid, out, index, err := decryptPKCS1v15(rand, priv, ciphertext)
 	if err != nil {
-		return
+		return nil, err
 	}
 	if valid == 0 {
 		return nil, ErrDecryption
 	}
-	out = out[index:]
-	return
+	return out[index:], nil
 }
 
 // DecryptPKCS1v15SessionKey decrypts a session key using RSA and the padding scheme from PKCS#1 v1.5.
@@ -103,7 +102,7 @@ func DecryptPKCS1v15(rand io.Reader, priv *PrivateKey, ciphertext []byte) (out [
 // a random value was used (because it'll be different for the same ciphertext)
 // and thus whether the padding was correct. This defeats the point of this
 // function. Using at least a 16-byte key will protect against this attack.
-func DecryptPKCS1v15SessionKey(rand io.Reader, priv *PrivateKey, ciphertext []byte, key []byte) (err error) {
+func DecryptPKCS1v15SessionKey(rand io.Reader, priv *PrivateKey, ciphertext []byte, key []byte) error {
 	if err := checkPub(&priv.PublicKey); err != nil {
 		return err
 	}
@@ -114,7 +113,7 @@ func DecryptPKCS1v15SessionKey(rand io.Reader, priv *PrivateKey, ciphertext []by
 
 	valid, em, index, err := decryptPKCS1v15(rand, priv, ciphertext)
 	if err != nil {
-		return
+		return err
 	}
 
 	if len(em) != k {
@@ -125,7 +124,7 @@ func DecryptPKCS1v15SessionKey(rand io.Reader, priv *PrivateKey, ciphertext []by
 
 	valid &= subtle.ConstantTimeEq(int32(len(em)-index), int32(len(key)))
 	subtle.ConstantTimeCopy(valid, key, em[len(em)-len(key):])
-	return
+	return nil
 }
 
 // decryptPKCS1v15 decrypts ciphertext using priv and blinds the operation if
@@ -213,21 +212,23 @@ var hashPrefixes = map[crypto.Hash][]byte{
 	crypto.RIPEMD160: {0x30, 0x20, 0x30, 0x08, 0x06, 0x06, 0x28, 0xcf, 0x06, 0x03, 0x00, 0x31, 0x04, 0x14},
 }
 
-// SignPKCS1v15 calculates the signature of hashed using RSASSA-PKCS1-V1_5-SIGN from RSA PKCS#1 v1.5.
-// Note that hashed must be the result of hashing the input message using the
-// given hash function. If hash is zero, hashed is signed directly. This isn't
+// SignPKCS1v15 calculates the signature of hashed using
+// RSASSA-PKCS1-V1_5-SIGN from RSA PKCS#1 v1.5.  Note that hashed must
+// be the result of hashing the input message using the given hash
+// function. If hash is zero, hashed is signed directly. This isn't
 // advisable except for interoperability.
 //
-// If rand is not nil then RSA blinding will be used to avoid timing side-channel attacks.
+// If rand is not nil then RSA blinding will be used to avoid timing
+// side-channel attacks.
 //
-// This function is deterministic. Thus, if the set of possible messages is
-// small, an attacker may be able to build a map from messages to signatures
-// and identify the signed messages. As ever, signatures provide authenticity,
-// not confidentiality.
-func SignPKCS1v15(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte) (s []byte, err error) {
+// This function is deterministic. Thus, if the set of possible
+// messages is small, an attacker may be able to build a map from
+// messages to signatures and identify the signed messages. As ever,
+// signatures provide authenticity, not confidentiality.
+func SignPKCS1v15(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte) ([]byte, error) {
 	hashLen, prefix, err := pkcs1v15HashInfo(hash, len(hashed))
 	if err != nil {
-		return
+		return nil, err
 	}
 
 	tLen := len(prefix) + hashLen
@@ -248,12 +249,11 @@ func SignPKCS1v15(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []b
 	m := new(big.Int).SetBytes(em)
 	c, err := decryptAndCheck(rand, priv, m)
 	if err != nil {
-		return
+		return nil, err
 	}
 
 	copyWithLeftPad(em, c.Bytes())
-	s = em
-	return
+	return em, nil
 }
 
 // VerifyPKCS1v15 verifies an RSA PKCS#1 v1.5 signature.
@@ -261,17 +261,16 @@ func SignPKCS1v15(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []b
 // function and sig is the signature. A valid signature is indicated by
 // returning a nil error. If hash is zero then hashed is used directly. This
 // isn't advisable except for interoperability.
-func VerifyPKCS1v15(pub *PublicKey, hash crypto.Hash, hashed []byte, sig []byte) (err error) {
+func VerifyPKCS1v15(pub *PublicKey, hash crypto.Hash, hashed []byte, sig []byte) error {
 	hashLen, prefix, err := pkcs1v15HashInfo(hash, len(hashed))
 	if err != nil {
-		return
+		return err
 	}
 
 	tLen := len(prefix) + hashLen
 	k := (pub.N.BitLen() + 7) / 8
 	if k < tLen+11 {
-		err = ErrVerification
-		return
+		return ErrVerification
 	}
 
 	c := new(big.Int).SetBytes(sig)
diff --git a/libgo/go/crypto/rsa/pss.go b/libgo/go/crypto/rsa/pss.go
index 8a94589b1c2..1ba194a4ad2 100644
--- a/libgo/go/crypto/rsa/pss.go
+++ b/libgo/go/crypto/rsa/pss.go
@@ -64,7 +64,7 @@ func emsaPSSEncode(mHash []byte, emBits int, salt []byte, hash hash.Hash) ([]byt
 	hash.Reset()
 
 	// 7.  Generate an octet string PS consisting of emLen - sLen - hLen - 2
-	//     zero octets.  The length of PS may be 0.
+	//     zero octets. The length of PS may be 0.
 	//
 	// 8.  Let DB = PS || 0x01 || salt; DB is an octet string of length
 	//     emLen - hLen - 1.
@@ -246,7 +246,7 @@ func (opts *PSSOptions) saltLength() int {
 // Note that hashed must be the result of hashing the input message using the
 // given hash function. The opts argument may be nil, in which case sensible
 // defaults are used.
-func SignPSS(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte, opts *PSSOptions) (s []byte, err error) {
+func SignPSS(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte, opts *PSSOptions) ([]byte, error) {
 	saltLength := opts.saltLength()
 	switch saltLength {
 	case PSSSaltLengthAuto:
@@ -260,8 +260,8 @@ func SignPSS(rand io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte,
 	}
 
 	salt := make([]byte, saltLength)
-	if _, err = io.ReadFull(rand, salt); err != nil {
-		return
+	if _, err := io.ReadFull(rand, salt); err != nil {
+		return nil, err
 	}
 	return signPSSWithSalt(rand, priv, hash, hashed, salt)
 }
diff --git a/libgo/go/crypto/rsa/rsa.go b/libgo/go/crypto/rsa/rsa.go
index 0f487fe1524..594305631b8 100644
--- a/libgo/go/crypto/rsa/rsa.go
+++ b/libgo/go/crypto/rsa/rsa.go
@@ -14,7 +14,7 @@
 // possible.
 //
 // Two sets of interfaces are included in this package. When a more abstract
-// interface isn't neccessary, there are functions for encrypting/decrypting
+// interface isn't necessary, there are functions for encrypting/decrypting
 // with v1.5/OAEP and signing/verifying with v1.5/PSS. If one needs to abstract
 // over the public-key primitive, the PrivateKey struct implements the
 // Decrypter and Signer interfaces from the crypto package.
@@ -191,7 +191,7 @@ func (priv *PrivateKey) Validate() error {
 
 // GenerateKey generates an RSA keypair of the given bit size using the
 // random source random (for example, crypto/rand.Reader).
-func GenerateKey(random io.Reader, bits int) (priv *PrivateKey, err error) {
+func GenerateKey(random io.Reader, bits int) (*PrivateKey, error) {
 	return GenerateMultiPrimeKey(random, 2, bits)
 }
 
@@ -206,8 +206,8 @@ func GenerateKey(random io.Reader, bits int) (priv *PrivateKey, err error) {
 //
 // [1] US patent 4405829 (1972, expired)
 // [2] http://www.cacr.math.uwaterloo.ca/techreports/2006/cacr2006-16.pdf
-func GenerateMultiPrimeKey(random io.Reader, nprimes int, bits int) (priv *PrivateKey, err error) {
-	priv = new(PrivateKey)
+func GenerateMultiPrimeKey(random io.Reader, nprimes int, bits int) (*PrivateKey, error) {
+	priv := new(PrivateKey)
 	priv.E = 65537
 
 	if nprimes < 2 {
@@ -234,6 +234,7 @@ NextSetOfPrimes:
 			todo += (nprimes - 2) / 5
 		}
 		for i := 0; i < nprimes; i++ {
+			var err error
 			primes[i], err = rand.Prime(random, todo/(nprimes-i))
 			if err != nil {
 				return nil, err
@@ -283,7 +284,7 @@ NextSetOfPrimes:
 	}
 
 	priv.Precompute()
-	return
+	return priv, nil
 }
 
 // incCounter increments a four byte, big-endian counter.
@@ -348,15 +349,14 @@ func encrypt(c *big.Int, pub *PublicKey, m *big.Int) *big.Int {
 //
 // The message must be no longer than the length of the public modulus less
 // twice the hash length plus 2.
-func EncryptOAEP(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, label []byte) (out []byte, err error) {
+func EncryptOAEP(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, label []byte) ([]byte, error) {
 	if err := checkPub(pub); err != nil {
 		return nil, err
 	}
 	hash.Reset()
 	k := (pub.N.BitLen() + 7) / 8
 	if len(msg) > k-2*hash.Size()-2 {
-		err = ErrMessageTooLong
-		return
+		return nil, ErrMessageTooLong
 	}
 
 	hash.Write(label)
@@ -371,9 +371,9 @@ func EncryptOAEP(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, l
 	db[len(db)-len(msg)-1] = 1
 	copy(db[len(db)-len(msg):], msg)
 
-	_, err = io.ReadFull(random, seed)
+	_, err := io.ReadFull(random, seed)
 	if err != nil {
-		return
+		return nil, err
 	}
 
 	mgf1XOR(db, hash, seed)
@@ -382,7 +382,7 @@ func EncryptOAEP(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, l
 	m := new(big.Int)
 	m.SetBytes(em)
 	c := encrypt(new(big.Int), pub, m)
-	out = c.Bytes()
+	out := c.Bytes()
 
 	if len(out) < k {
 		// If the output is too small, we need to left-pad with zeros.
@@ -391,7 +391,7 @@ func EncryptOAEP(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, l
 		out = t
 	}
 
-	return
+	return out, nil
 }
 
 // ErrDecryption represents a failure to decrypt a message.
@@ -565,22 +565,21 @@ func decryptAndCheck(random io.Reader, priv *PrivateKey, c *big.Int) (m *big.Int
 //
 // The label parameter must match the value given when encrypting. See
 // EncryptOAEP for details.
-func DecryptOAEP(hash hash.Hash, random io.Reader, priv *PrivateKey, ciphertext []byte, label []byte) (msg []byte, err error) {
+func DecryptOAEP(hash hash.Hash, random io.Reader, priv *PrivateKey, ciphertext []byte, label []byte) ([]byte, error) {
 	if err := checkPub(&priv.PublicKey); err != nil {
 		return nil, err
 	}
 	k := (priv.N.BitLen() + 7) / 8
 	if len(ciphertext) > k ||
 		k < hash.Size()*2+2 {
-		err = ErrDecryption
-		return
+		return nil, ErrDecryption
 	}
 
 	c := new(big.Int).SetBytes(ciphertext)
 
 	m, err := decrypt(random, priv, c)
 	if err != nil {
-		return
+		return nil, err
 	}
 
 	hash.Write(label)
@@ -628,12 +627,10 @@ func DecryptOAEP(hash hash.Hash, random io.Reader, priv *PrivateKey, ciphertext
 	}
 
 	if firstByteIsZero&lHash2Good&^invalid&^lookingForIndex != 1 {
-		err = ErrDecryption
-		return
+		return nil, ErrDecryption
 	}
 
-	msg = rest[index+1:]
-	return
+	return rest[index+1:], nil
 }
 
 // leftPad returns a new slice of length size. The contents of input are right
diff --git a/libgo/go/crypto/sha1/fallback_test.go b/libgo/go/crypto/sha1/fallback_test.go
new file mode 100644
index 00000000000..08acd044d01
--- /dev/null
+++ b/libgo/go/crypto/sha1/fallback_test.go
@@ -0,0 +1,34 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build s390x
+
+package sha1
+
+import (
+	"fmt"
+	"io"
+	"testing"
+)
+
+// Tests the fallback code path in case the optimized asm
+// implementation cannot be used.
+// See also TestBlockGeneric.
+func TestGenericPath(t *testing.T) {
+	if useAsm == false {
+		t.Skipf("assembly implementation unavailable")
+	}
+	useAsm = false
+	defer func() { useAsm = true }()
+	c := New()
+	in := "ΑΒΓΔΕϜΖΗΘΙΚΛΜΝΞΟΠϺϘΡΣΤΥΦΧΨΩ"
+	gold := "0f58c2bb130f8182375f325c18342215255387e5"
+	if _, err := io.WriteString(c, in); err != nil {
+		t.Fatalf("could not write to c: %v", err)
+	}
+	out := fmt.Sprintf("%x", c.Sum(nil))
+	if out != gold {
+		t.Fatalf("mismatch: got %s, wanted %s", out, gold)
+	}
+}
diff --git a/libgo/go/crypto/sha1/issue15617_test.go b/libgo/go/crypto/sha1/issue15617_test.go
new file mode 100644
index 00000000000..98038e58077
--- /dev/null
+++ b/libgo/go/crypto/sha1/issue15617_test.go
@@ -0,0 +1,28 @@
+// +build amd64
+// +build linux darwin
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha1_test
+
+import (
+	"crypto/sha1"
+	"syscall"
+	"testing"
+)
+
+func TestOutOfBoundsRead(t *testing.T) {
+	const pageSize = 4 << 10
+	data, err := syscall.Mmap(0, 0, 2*pageSize, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
+	if err != nil {
+		panic(err)
+	}
+	if err := syscall.Mprotect(data[pageSize:], syscall.PROT_NONE); err != nil {
+		panic(err)
+	}
+	for i := 0; i < pageSize; i++ {
+		sha1.Sum(data[pageSize-i : pageSize])
+	}
+}
diff --git a/libgo/go/crypto/sha1/sha1.go b/libgo/go/crypto/sha1/sha1.go
index 9f1a96e3649..ac593b1bf0d 100644
--- a/libgo/go/crypto/sha1/sha1.go
+++ b/libgo/go/crypto/sha1/sha1.go
@@ -90,7 +90,7 @@ func (d0 *digest) Sum(in []byte) []byte {
 
 func (d *digest) checkSum() [Size]byte {
 	len := d.len
-	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
+	// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
 	var tmp [64]byte
 	tmp[0] = 0x80
 	if len%64 < 56 {
diff --git a/libgo/go/crypto/sha1/sha1_test.go b/libgo/go/crypto/sha1/sha1_test.go
index 4a629518b76..214afc51e1f 100644
--- a/libgo/go/crypto/sha1/sha1_test.go
+++ b/libgo/go/crypto/sha1/sha1_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// SHA1 hash algorithm.  See RFC 3174.
+// SHA1 hash algorithm. See RFC 3174.
 
 package sha1
 
@@ -19,6 +19,7 @@ type sha1Test struct {
 }
 
 var golden = []sha1Test{
+	{"76245dbf96f661bd221046197ab8b9f063f11bad", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"},
 	{"da39a3ee5e6b4b0d3255bfef95601890afd80709", ""},
 	{"86f7e437faa5a7fce15d1ddcb9eaeaea377667b8", "a"},
 	{"da23614e02469a0d7c7bd1bdab5c9c474b1904dc", "ab"},
@@ -91,15 +92,17 @@ func TestBlockSize(t *testing.T) {
 	}
 }
 
-// Tests that blockGeneric (pure Go) and block (in assembly for amd64, 386, arm) match.
+// Tests that blockGeneric (pure Go) and block (in assembly for some architectures) match.
 func TestBlockGeneric(t *testing.T) {
-	gen, asm := New().(*digest), New().(*digest)
-	buf := make([]byte, BlockSize*20) // arbitrary factor
-	rand.Read(buf)
-	blockGeneric(gen, buf)
-	block(asm, buf)
-	if *gen != *asm {
-		t.Error("block and blockGeneric resulted in different states")
+	for i := 1; i < 30; i++ { // arbitrary factor
+		gen, asm := New().(*digest), New().(*digest)
+		buf := make([]byte, BlockSize*i)
+		rand.Read(buf)
+		blockGeneric(gen, buf)
+		block(asm, buf)
+		if *gen != *asm {
+			t.Errorf("For %#v block and blockGeneric resulted in different states", buf)
+		}
 	}
 }
 
@@ -120,6 +123,10 @@ func BenchmarkHash8Bytes(b *testing.B) {
 	benchmarkSize(b, 8)
 }
 
+func BenchmarkHash320Bytes(b *testing.B) {
+	benchmarkSize(b, 320)
+}
+
 func BenchmarkHash1K(b *testing.B) {
 	benchmarkSize(b, 1024)
 }
diff --git a/libgo/go/crypto/sha1/sha1block_amd64.go b/libgo/go/crypto/sha1/sha1block_amd64.go
new file mode 100644
index 00000000000..fd85a4262be
--- /dev/null
+++ b/libgo/go/crypto/sha1/sha1block_amd64.go
@@ -0,0 +1,34 @@
+// Copyright 2016 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha1
+
+//go:noescape
+
+func blockAVX2(dig *digest, p []byte)
+
+//go:noescape
+func blockAMD64(dig *digest, p []byte)
+func checkAVX2() bool
+
+var hasAVX2 = checkAVX2()
+
+func block(dig *digest, p []byte) {
+	if hasAVX2 && len(p) >= 256 {
+		// blockAVX2 calculates sha1 for 2 block per iteration
+		// it also interleaves precalculation for next block.
+		// So it may read up-to 192 bytes past end of p
+		// We may add checks inside blockAVX2, but this will
+		// just turn it into a copy of blockAMD64,
+		// so call it directly, instead.
+		safeLen := len(p) - 128
+		if safeLen%128 != 0 {
+			safeLen -= 64
+		}
+		blockAVX2(dig, p[:safeLen])
+		blockAMD64(dig, p[safeLen:])
+	} else {
+		blockAMD64(dig, p)
+	}
+}
diff --git a/libgo/go/crypto/sha1/sha1block_decl.go b/libgo/go/crypto/sha1/sha1block_decl.go
index 24e521af1fc..6d2d073d137 100644
--- a/libgo/go/crypto/sha1/sha1block_decl.go
+++ b/libgo/go/crypto/sha1/sha1block_decl.go
@@ -1,8 +1,8 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64 amd64p32 arm 386
+// +build amd64p32 arm 386 s390x
 
 package sha1
 
diff --git a/libgo/go/crypto/sha1/sha1block_generic.go b/libgo/go/crypto/sha1/sha1block_generic.go
index 696e26b6257..f0194626a6f 100644
--- a/libgo/go/crypto/sha1/sha1block_generic.go
+++ b/libgo/go/crypto/sha1/sha1block_generic.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64,!amd64p32,!386,!arm
+// +build !amd64,!amd64p32,!386,!arm,!s390x
 
 package sha1
 
diff --git a/libgo/go/crypto/sha1/sha1block_s390x.go b/libgo/go/crypto/sha1/sha1block_s390x.go
new file mode 100644
index 00000000000..aac7c1182d4
--- /dev/null
+++ b/libgo/go/crypto/sha1/sha1block_s390x.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha1
+
+// featureCheck reports whether the CPU supports the
+// SHA1 compute intermediate message digest (KIMD)
+// function code.
+func featureCheck() bool
+
+var useAsm = featureCheck()
diff --git a/libgo/go/crypto/sha256/fallback_test.go b/libgo/go/crypto/sha256/fallback_test.go
new file mode 100644
index 00000000000..5917a4862af
--- /dev/null
+++ b/libgo/go/crypto/sha256/fallback_test.go
@@ -0,0 +1,35 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build s390x
+
+package sha256
+
+import (
+	"fmt"
+	"io"
+	"testing"
+)
+
+// Tests the fallback code path in case the optimized asm
+// implementation cannot be used.
+// See also TestBlockGeneric.
+func TestGenericPath(t *testing.T) {
+	if useAsm == false {
+		t.Skipf("assembly implementation unavailable")
+	}
+	useAsm = false
+	defer func() { useAsm = true }()
+	c := New()
+	in := "ΑΒΓΔΕϜΖΗΘΙΚΛΜΝΞΟΠϺϘΡΣΤΥΦΧΨΩ"
+	gold := "e93d84ec2b22383123be9f713697fb25" +
+		"338c86e2f7d8d1ddc2d89d332dd9d76c"
+	if _, err := io.WriteString(c, in); err != nil {
+		t.Fatalf("could not write to c: %v", err)
+	}
+	out := fmt.Sprintf("%x", c.Sum(nil))
+	if out != gold {
+		t.Fatalf("mismatch: got %s, wanted %s", out, gold)
+	}
+}
diff --git a/libgo/go/crypto/sha256/sha256.go b/libgo/go/crypto/sha256/sha256.go
index d84cebf2ff2..74b05b92d77 100644
--- a/libgo/go/crypto/sha256/sha256.go
+++ b/libgo/go/crypto/sha256/sha256.go
@@ -137,7 +137,7 @@ func (d0 *digest) Sum(in []byte) []byte {
 
 func (d *digest) checkSum() [Size]byte {
 	len := d.len
-	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
+	// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
 	var tmp [64]byte
 	tmp[0] = 0x80
 	if len%64 < 56 {
diff --git a/libgo/go/crypto/sha256/sha256_test.go b/libgo/go/crypto/sha256/sha256_test.go
index 1d883d39059..279cf5ad407 100644
--- a/libgo/go/crypto/sha256/sha256_test.go
+++ b/libgo/go/crypto/sha256/sha256_test.go
@@ -2,11 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// SHA256 hash algorithm.  See FIPS 180-2.
+// SHA256 hash algorithm. See FIPS 180-2.
 
 package sha256
 
 import (
+	"crypto/rand"
 	"fmt"
 	"io"
 	"testing"
@@ -150,6 +151,18 @@ func TestBlockSize(t *testing.T) {
 	}
 }
 
+// Tests that blockGeneric (pure Go) and block (in assembly for some architectures) match.
+func TestBlockGeneric(t *testing.T) {
+	gen, asm := New().(*digest), New().(*digest)
+	buf := make([]byte, BlockSize*20) // arbitrary factor
+	rand.Read(buf)
+	blockGeneric(gen, buf)
+	block(asm, buf)
+	if *gen != *asm {
+		t.Error("block and blockGeneric resulted in different states")
+	}
+}
+
 var bench = New()
 var buf = make([]byte, 8192)
 
diff --git a/libgo/go/crypto/sha256/sha256block.go b/libgo/go/crypto/sha256/sha256block.go
index ca5efd156a9..d43bbf02453 100644
--- a/libgo/go/crypto/sha256/sha256block.go
+++ b/libgo/go/crypto/sha256/sha256block.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !386,!amd64
-
 // SHA256 block step.
 // In its own file so that a faster assembly or C version
 // can be substituted easily.
@@ -77,7 +75,7 @@ var _K = []uint32{
 	0xc67178f2,
 }
 
-func block(dig *digest, p []byte) {
+func blockGeneric(dig *digest, p []byte) {
 	var w [64]uint32
 	h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
 	for len(p) >= chunk {
diff --git a/libgo/go/crypto/sha256/sha256block_decl.go b/libgo/go/crypto/sha256/sha256block_decl.go
index a50c9787108..e6caff9a746 100644
--- a/libgo/go/crypto/sha256/sha256block_decl.go
+++ b/libgo/go/crypto/sha256/sha256block_decl.go
@@ -1,8 +1,8 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build 386 amd64
+// +build 386 amd64 s390x
 
 package sha256
 
diff --git a/libgo/go/crypto/sha256/sha256block_generic.go b/libgo/go/crypto/sha256/sha256block_generic.go
new file mode 100644
index 00000000000..1a01969b0dc
--- /dev/null
+++ b/libgo/go/crypto/sha256/sha256block_generic.go
@@ -0,0 +1,9 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !amd64,!386,!s390x
+
+package sha256
+
+var block = blockGeneric
diff --git a/libgo/go/crypto/sha256/sha256block_s390x.go b/libgo/go/crypto/sha256/sha256block_s390x.go
new file mode 100644
index 00000000000..b7beefef0c6
--- /dev/null
+++ b/libgo/go/crypto/sha256/sha256block_s390x.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha256
+
+// featureCheck reports whether the CPU supports the
+// SHA256 compute intermediate message digest (KIMD)
+// function code.
+func featureCheck() bool
+
+var useAsm = featureCheck()
diff --git a/libgo/go/crypto/sha512/fallback_test.go b/libgo/go/crypto/sha512/fallback_test.go
new file mode 100644
index 00000000000..9024ce668a0
--- /dev/null
+++ b/libgo/go/crypto/sha512/fallback_test.go
@@ -0,0 +1,37 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build s390x
+
+package sha512
+
+import (
+	"fmt"
+	"io"
+	"testing"
+)
+
+// Tests the fallback code path in case the optimized asm
+// implementation cannot be used.
+// See also TestBlockGeneric.
+func TestGenericPath(t *testing.T) {
+	if useAsm == false {
+		t.Skipf("assembly implementation unavailable")
+	}
+	useAsm = false
+	defer func() { useAsm = true }()
+	c := New()
+	in := "ΑΒΓΔΕϜΖΗΘΙΚΛΜΝΞΟΠϺϘΡΣΤΥΦΧΨΩ"
+	gold := "6922e319366d677f34c504af31bfcb29" +
+		"e531c125ecd08679362bffbd6b6ebfb9" +
+		"0dcc27dfc1f3d3b16a16c0763cf43b91" +
+		"40bbf9bbb7233724e9a0c6655b185d76"
+	if _, err := io.WriteString(c, in); err != nil {
+		t.Fatalf("could not write to c: %v", err)
+	}
+	out := fmt.Sprintf("%x", c.Sum(nil))
+	if out != gold {
+		t.Fatalf("mismatch: got %s, wanted %s", out, gold)
+	}
+}
diff --git a/libgo/go/crypto/sha512/sha512.go b/libgo/go/crypto/sha512/sha512.go
index e7781fd2f41..5603c90fb74 100644
--- a/libgo/go/crypto/sha512/sha512.go
+++ b/libgo/go/crypto/sha512/sha512.go
@@ -208,7 +208,7 @@ func (d0 *digest) Sum(in []byte) []byte {
 }
 
 func (d *digest) checkSum() [Size]byte {
-	// Padding.  Add a 1 bit and 0 bits until 112 bytes mod 128.
+	// Padding. Add a 1 bit and 0 bits until 112 bytes mod 128.
 	len := d.len
 	var tmp [128]byte
 	tmp[0] = 0x80
diff --git a/libgo/go/crypto/sha512/sha512_test.go b/libgo/go/crypto/sha512/sha512_test.go
index 04b3d4a3cc0..a3a136a19f8 100644
--- a/libgo/go/crypto/sha512/sha512_test.go
+++ b/libgo/go/crypto/sha512/sha512_test.go
@@ -2,11 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// SHA512 hash algorithm.  See FIPS 180-4.
+// SHA512 hash algorithm. See FIPS 180-4.
 
 package sha512
 
 import (
+	"crypto/rand"
 	"encoding/hex"
 	"hash"
 	"io"
@@ -304,6 +305,18 @@ func TestBlockSize(t *testing.T) {
 	}
 }
 
+// Tests that blockGeneric (pure Go) and block (in assembly for some architectures) match.
+func TestBlockGeneric(t *testing.T) {
+	gen, asm := New().(*digest), New().(*digest)
+	buf := make([]byte, BlockSize*20) // arbitrary factor
+	rand.Read(buf)
+	blockGeneric(gen, buf)
+	block(asm, buf)
+	if *gen != *asm {
+		t.Error("block and blockGeneric resulted in different states")
+	}
+}
+
 var bench = New()
 var buf = make([]byte, 8192)
 
diff --git a/libgo/go/crypto/sha512/sha512block.go b/libgo/go/crypto/sha512/sha512block.go
index 648ae8f7e1f..42e8d19fe8c 100644
--- a/libgo/go/crypto/sha512/sha512block.go
+++ b/libgo/go/crypto/sha512/sha512block.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !amd64
-
 // SHA512 block step.
 // In its own file so that a faster assembly or C version
 // can be substituted easily.
@@ -93,7 +91,7 @@ var _K = []uint64{
 	0x6c44198c4a475817,
 }
 
-func block(dig *digest, p []byte) {
+func blockGeneric(dig *digest, p []byte) {
 	var w [80]uint64
 	h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
 	for len(p) >= chunk {
diff --git a/libgo/go/crypto/sha512/sha512block_decl.go b/libgo/go/crypto/sha512/sha512block_decl.go
index bef99de2e46..47d656a7e4a 100644
--- a/libgo/go/crypto/sha512/sha512block_decl.go
+++ b/libgo/go/crypto/sha512/sha512block_decl.go
@@ -1,8 +1,8 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64
+// +build amd64 s390x
 
 package sha512
 
diff --git a/libgo/go/crypto/sha512/sha512block_generic.go b/libgo/go/crypto/sha512/sha512block_generic.go
new file mode 100644
index 00000000000..2c691baa3d9
--- /dev/null
+++ b/libgo/go/crypto/sha512/sha512block_generic.go
@@ -0,0 +1,9 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !amd64,!s390x
+
+package sha512
+
+var block = blockGeneric
diff --git a/libgo/go/crypto/sha512/sha512block_s390x.go b/libgo/go/crypto/sha512/sha512block_s390x.go
new file mode 100644
index 00000000000..f05dc18e124
--- /dev/null
+++ b/libgo/go/crypto/sha512/sha512block_s390x.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha512
+
+// featureCheck reports whether the CPU supports the
+// SHA512 compute intermediate message digest (KIMD)
+// function code.
+func featureCheck() bool
+
+var useAsm = featureCheck()
diff --git a/libgo/go/crypto/subtle/constant_time.go b/libgo/go/crypto/subtle/constant_time.go
index 6f80e7c58dc..11312b8dd44 100644
--- a/libgo/go/crypto/subtle/constant_time.go
+++ b/libgo/go/crypto/subtle/constant_time.go
@@ -6,7 +6,7 @@
 // code but require careful thought to use correctly.
 package subtle
 
-// ConstantTimeCompare returns 1 iff the two slices, x
+// ConstantTimeCompare returns 1 if and only if the two slices, x
 // and y, have equal contents. The time taken is a function of the length of
 // the slices and is independent of the contents.
 func ConstantTimeCompare(x, y []byte) int {
diff --git a/libgo/go/crypto/tls/alert.go b/libgo/go/crypto/tls/alert.go
index 3de4834d3f5..9cf99224f5d 100644
--- a/libgo/go/crypto/tls/alert.go
+++ b/libgo/go/crypto/tls/alert.go
@@ -69,9 +69,9 @@ var alertText = map[alert]string{
 func (e alert) String() string {
 	s, ok := alertText[e]
 	if ok {
-		return s
+		return "tls: " + s
 	}
-	return "alert(" + strconv.Itoa(int(e)) + ")"
+	return "tls: alert(" + strconv.Itoa(int(e)) + ")"
 }
 
 func (e alert) Error() string {
diff --git a/libgo/go/crypto/tls/cipher_suites.go b/libgo/go/crypto/tls/cipher_suites.go
index 869ffa50bd3..e69f5f966e3 100644
--- a/libgo/go/crypto/tls/cipher_suites.go
+++ b/libgo/go/crypto/tls/cipher_suites.go
@@ -74,7 +74,7 @@ type cipherSuite struct {
 
 var cipherSuites = []*cipherSuite{
 	// Ciphersuite order is chosen so that ECDHE comes before plain RSA
-	// and RC4 comes before AES (because of the Lucky13 attack).
+	// and RC4 comes before AES-CBC (because of the Lucky13 attack).
 	{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM},
 	{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM},
 	{TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
@@ -261,8 +261,10 @@ func mutualCipherSuite(have []uint16, want uint16) *cipherSuite {
 	return nil
 }
 
-// A list of the possible cipher suite ids. Taken from
-// http://www.iana.org/assignments/tls-parameters/tls-parameters.xml
+// A list of cipher suite IDs that are, or have been, implemented by this
+// package.
+//
+// Taken from http://www.iana.org/assignments/tls-parameters/tls-parameters.xml
 const (
 	TLS_RSA_WITH_RC4_128_SHA                uint16 = 0x0005
 	TLS_RSA_WITH_3DES_EDE_CBC_SHA           uint16 = 0x000a
@@ -284,6 +286,6 @@ const (
 
 	// TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
 	// that the client is doing version fallback. See
-	// https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00.
+	// https://tools.ietf.org/html/rfc7507.
 	TLS_FALLBACK_SCSV uint16 = 0x5600
 )
diff --git a/libgo/go/crypto/tls/common.go b/libgo/go/crypto/tls/common.go
index c68ebfe188b..9fc74200820 100644
--- a/libgo/go/crypto/tls/common.go
+++ b/libgo/go/crypto/tls/common.go
@@ -48,6 +48,7 @@ const (
 
 // TLS handshake message types.
 const (
+	typeHelloRequest       uint8 = 0
 	typeClientHello        uint8 = 1
 	typeServerHello        uint8 = 2
 	typeNewSessionTicket   uint8 = 4
@@ -114,7 +115,7 @@ const (
 	certTypeRSAFixedDH = 3 // A certificate containing a static DH key
 	certTypeDSSFixedDH = 4 // A certificate containing a static DH key
 
-	// See RFC4492 sections 3 and 5.5.
+	// See RFC 4492 sections 3 and 5.5.
 	certTypeECDSASign      = 64 // A certificate containing an ECDSA-capable public key, signed with ECDSA.
 	certTypeRSAFixedECDH   = 65 // A certificate containing an ECDH-capable public key, signed with RSA.
 	certTypeECDSAFixedECDH = 66 // A certificate containing an ECDH-capable public key, signed with ECDSA.
@@ -238,6 +239,33 @@ type ClientHelloInfo struct {
 	SupportedPoints []uint8
 }
 
+// RenegotiationSupport enumerates the different levels of support for TLS
+// renegotiation. TLS renegotiation is the act of performing subsequent
+// handshakes on a connection after the first. This significantly complicates
+// the state machine and has been the source of numerous, subtle security
+// issues. Initiating a renegotiation is not supported, but support for
+// accepting renegotiation requests may be enabled.
+//
+// Even when enabled, the server may not change its identity between handshakes
+// (i.e. the leaf certificate must be the same). Additionally, concurrent
+// handshake and application data flow is not permitted so renegotiation can
+// only be used with protocols that synchronise with the renegotiation, such as
+// HTTPS.
+type RenegotiationSupport int
+
+const (
+	// RenegotiateNever disables renegotiation.
+	RenegotiateNever RenegotiationSupport = iota
+
+	// RenegotiateOnceAsClient allows a remote server to request
+	// renegotiation once per connection.
+	RenegotiateOnceAsClient
+
+	// RenegotiateFreelyAsClient allows a remote server to repeatedly
+	// request renegotiation.
+	RenegotiateFreelyAsClient
+)
+
 // A Config structure is used to configure a TLS client or server.
 // After one has been passed to a TLS function it must not be
 // modified. A Config may be reused; the tls package will also not
@@ -349,6 +377,16 @@ type Config struct {
 	// be used.
 	CurvePreferences []CurveID
 
+	// DynamicRecordSizingDisabled disables adaptive sizing of TLS records.
+	// When true, the largest possible TLS record size is always used. When
+	// false, the size of TLS records may be adjusted in an attempt to
+	// improve latency.
+	DynamicRecordSizingDisabled bool
+
+	// Renegotiation controls what types of renegotiation are supported.
+	// The default, none, is correct for the vast majority of applications.
+	Renegotiation RenegotiationSupport
+
 	serverInitOnce sync.Once // guards calling (*Config).serverInit
 
 	// mutex protects sessionTicketKeys
@@ -384,6 +422,33 @@ func ticketKeyFromBytes(b [32]byte) (key ticketKey) {
 	return key
 }
 
+// clone returns a copy of c. Only the exported fields are copied.
+func (c *Config) clone() *Config {
+	return &Config{
+		Rand:                        c.Rand,
+		Time:                        c.Time,
+		Certificates:                c.Certificates,
+		NameToCertificate:           c.NameToCertificate,
+		GetCertificate:              c.GetCertificate,
+		RootCAs:                     c.RootCAs,
+		NextProtos:                  c.NextProtos,
+		ServerName:                  c.ServerName,
+		ClientAuth:                  c.ClientAuth,
+		ClientCAs:                   c.ClientCAs,
+		InsecureSkipVerify:          c.InsecureSkipVerify,
+		CipherSuites:                c.CipherSuites,
+		PreferServerCipherSuites:    c.PreferServerCipherSuites,
+		SessionTicketsDisabled:      c.SessionTicketsDisabled,
+		SessionTicketKey:            c.SessionTicketKey,
+		ClientSessionCache:          c.ClientSessionCache,
+		MinVersion:                  c.MinVersion,
+		MaxVersion:                  c.MaxVersion,
+		CurvePreferences:            c.CurvePreferences,
+		DynamicRecordSizingDisabled: c.DynamicRecordSizingDisabled,
+		Renegotiation:               c.Renegotiation,
+	}
+}
+
 func (c *Config) serverInit() {
 	if c.SessionTicketsDisabled {
 		return
@@ -510,7 +575,7 @@ func (c *Config) getCertificate(clientHello *ClientHelloInfo) (*Certificate, err
 	}
 
 	if len(c.Certificates) == 0 {
-		return nil, errors.New("crypto/tls: no certificates configured")
+		return nil, errors.New("tls: no certificates configured")
 	}
 
 	if len(c.Certificates) == 1 || c.NameToCertificate == nil {
@@ -584,13 +649,6 @@ type Certificate struct {
 	Leaf *x509.Certificate
 }
 
-// A TLS record.
-type record struct {
-	contentType  recordType
-	major, minor uint8
-	payload      []byte
-}
-
 type handshakeMessage interface {
 	marshal() []byte
 	unmarshal([]byte) bool
diff --git a/libgo/go/crypto/tls/conn.go b/libgo/go/crypto/tls/conn.go
index 03775685fb6..87bef23d91f 100644
--- a/libgo/go/crypto/tls/conn.go
+++ b/libgo/go/crypto/tls/conn.go
@@ -28,34 +28,60 @@ type Conn struct {
 	isClient bool
 
 	// constant after handshake; protected by handshakeMutex
-	handshakeMutex    sync.Mutex // handshakeMutex < in.Mutex, out.Mutex, errMutex
-	handshakeErr      error      // error resulting from handshake
-	vers              uint16     // TLS version
-	haveVers          bool       // version has been negotiated
-	config            *Config    // configuration passed to constructor
+	handshakeMutex sync.Mutex // handshakeMutex < in.Mutex, out.Mutex, errMutex
+	handshakeErr   error      // error resulting from handshake
+	vers           uint16     // TLS version
+	haveVers       bool       // version has been negotiated
+	config         *Config    // configuration passed to constructor
+	// handshakeComplete is true if the connection is currently transfering
+	// application data (i.e. is not currently processing a handshake).
 	handshakeComplete bool
-	didResume         bool // whether this connection was a session resumption
-	cipherSuite       uint16
-	ocspResponse      []byte   // stapled OCSP response
-	scts              [][]byte // signed certificate timestamps from server
-	peerCertificates  []*x509.Certificate
+	// handshakes counts the number of handshakes performed on the
+	// connection so far. If renegotiation is disabled then this is either
+	// zero or one.
+	handshakes       int
+	didResume        bool // whether this connection was a session resumption
+	cipherSuite      uint16
+	ocspResponse     []byte   // stapled OCSP response
+	scts             [][]byte // signed certificate timestamps from server
+	peerCertificates []*x509.Certificate
 	// verifiedChains contains the certificate chains that we built, as
 	// opposed to the ones presented by the server.
 	verifiedChains [][]*x509.Certificate
 	// serverName contains the server name indicated by the client, if any.
 	serverName string
-	// firstFinished contains the first Finished hash sent during the
-	// handshake. This is the "tls-unique" channel binding value.
-	firstFinished [12]byte
+	// secureRenegotiation is true if the server echoed the secure
+	// renegotiation extension. (This is meaningless as a server because
+	// renegotiation is not supported in that case.)
+	secureRenegotiation bool
+
+	// clientFinishedIsFirst is true if the client sent the first Finished
+	// message during the most recent handshake. This is recorded because
+	// the first transmitted Finished message is the tls-unique
+	// channel-binding value.
+	clientFinishedIsFirst bool
+	// clientFinished and serverFinished contain the Finished message sent
+	// by the client or server in the most recent handshake. This is
+	// retained to support the renegotiation extension and tls-unique
+	// channel-binding.
+	clientFinished [12]byte
+	serverFinished [12]byte
 
 	clientProtocol         string
 	clientProtocolFallback bool
 
 	// input/output
-	in, out  halfConn     // in.Mutex < out.Mutex
-	rawInput *block       // raw input, right off the wire
-	input    *block       // application data waiting to be read
-	hand     bytes.Buffer // handshake data waiting to be read
+	in, out   halfConn     // in.Mutex < out.Mutex
+	rawInput  *block       // raw input, right off the wire
+	input     *block       // application data waiting to be read
+	hand      bytes.Buffer // handshake data waiting to be read
+	buffering bool         // whether records are buffered in sendBuf
+	sendBuf   []byte       // a buffer of records waiting to be sent
+
+	// bytesSent counts the bytes of application data sent.
+	// packetsSent counts packets.
+	bytesSent   int64
+	packetsSent int64
 
 	// activeCall is an atomic int32; the low bit is whether Close has
 	// been called. the rest of the bits are the number of goroutines
@@ -124,13 +150,6 @@ func (hc *halfConn) setErrorLocked(err error) error {
 	return err
 }
 
-func (hc *halfConn) error() error {
-	hc.Lock()
-	err := hc.err
-	hc.Unlock()
-	return err
-}
-
 // prepareCipherSpec sets the encryption and MAC states
 // that a subsequent changeCipherSpec will use.
 func (hc *halfConn) prepareCipherSpec(version uint16, cipher interface{}, mac macFunction) {
@@ -170,13 +189,6 @@ func (hc *halfConn) incSeq() {
 	panic("TLS: sequence number wraparound")
 }
 
-// resetSeq resets the sequence number to zero.
-func (hc *halfConn) resetSeq() {
-	for i := range hc.seq {
-		hc.seq[i] = 0
-	}
-}
-
 // removePadding returns an unpadded slice, in constant time, which is a prefix
 // of the input. It also returns a byte which is equal to 255 if the padding
 // was valid and 0 otherwise. See RFC 2246, section 6.2.3.2
@@ -535,7 +547,7 @@ func (c *Conn) newRecordHeaderError(msg string) (err RecordHeaderError) {
 func (c *Conn) readRecord(want recordType) error {
 	// Caller must be in sync with connection:
 	// handshake data if handshake not yet completed,
-	// else application data.  (We don't support renegotiation.)
+	// else application data.
 	switch want {
 	default:
 		c.sendAlert(alertInternalError)
@@ -543,12 +555,12 @@ func (c *Conn) readRecord(want recordType) error {
 	case recordTypeHandshake, recordTypeChangeCipherSpec:
 		if c.handshakeComplete {
 			c.sendAlert(alertInternalError)
-			return c.in.setErrorLocked(errors.New("tls: handshake or ChangeCipherSpec requested after handshake complete"))
+			return c.in.setErrorLocked(errors.New("tls: handshake or ChangeCipherSpec requested while not in handshake"))
 		}
 	case recordTypeApplicationData:
 		if !c.handshakeComplete {
 			c.sendAlert(alertInternalError)
-			return c.in.setErrorLocked(errors.New("tls: application data record requested before handshake complete"))
+			return c.in.setErrorLocked(errors.New("tls: application data record requested while in handshake"))
 		}
 	}
 
@@ -672,7 +684,7 @@ Again:
 
 	case recordTypeHandshake:
 		// TODO(rsc): Should at least pick off connection close.
-		if typ != want {
+		if typ != want && !(c.isClient && c.config.Renegotiation != RenegotiateNever) {
 			return c.in.setErrorLocked(c.sendAlert(alertNoRenegotiation))
 		}
 		c.hand.Write(data)
@@ -694,12 +706,14 @@ func (c *Conn) sendAlertLocked(err alert) error {
 		c.tmp[0] = alertLevelError
 	}
 	c.tmp[1] = byte(err)
-	c.writeRecord(recordTypeAlert, c.tmp[0:2])
-	// closeNotify is a special case in that it isn't an error:
-	if err != alertCloseNotify {
-		return c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
+
+	_, writeErr := c.writeRecordLocked(recordTypeAlert, c.tmp[0:2])
+	if err == alertCloseNotify {
+		// closeNotify is a special case in that it isn't an error.
+		return writeErr
 	}
-	return nil
+
+	return c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
 }
 
 // sendAlert sends a TLS alert message.
@@ -710,16 +724,120 @@ func (c *Conn) sendAlert(err alert) error {
 	return c.sendAlertLocked(err)
 }
 
-// writeRecord writes a TLS record with the given type and payload
-// to the connection and updates the record layer state.
+const (
+	// tcpMSSEstimate is a conservative estimate of the TCP maximum segment
+	// size (MSS). A constant is used, rather than querying the kernel for
+	// the actual MSS, to avoid complexity. The value here is the IPv6
+	// minimum MTU (1280 bytes) minus the overhead of an IPv6 header (40
+	// bytes) and a TCP header with timestamps (32 bytes).
+	tcpMSSEstimate = 1208
+
+	// recordSizeBoostThreshold is the number of bytes of application data
+	// sent after which the TLS record size will be increased to the
+	// maximum.
+	recordSizeBoostThreshold = 128 * 1024
+)
+
+// maxPayloadSizeForWrite returns the maximum TLS payload size to use for the
+// next application data record. There is the following trade-off:
+//
+//   - For latency-sensitive applications, such as web browsing, each TLS
+//     record should fit in one TCP segment.
+//   - For throughput-sensitive applications, such as large file transfers,
+//     larger TLS records better amortize framing and encryption overheads.
+//
+// A simple heuristic that works well in practice is to use small records for
+// the first 1MB of data, then use larger records for subsequent data, and
+// reset back to smaller records after the connection becomes idle. See "High
+// Performance Web Networking", Chapter 4, or:
+// https://www.igvita.com/2013/10/24/optimizing-tls-record-size-and-buffering-latency/
+//
+// In the interests of simplicity and determinism, this code does not attempt
+// to reset the record size once the connection is idle, however.
+//
+// c.out.Mutex <= L.
+func (c *Conn) maxPayloadSizeForWrite(typ recordType, explicitIVLen int) int {
+	if c.config.DynamicRecordSizingDisabled || typ != recordTypeApplicationData {
+		return maxPlaintext
+	}
+
+	if c.bytesSent >= recordSizeBoostThreshold {
+		return maxPlaintext
+	}
+
+	// Subtract TLS overheads to get the maximum payload size.
+	macSize := 0
+	if c.out.mac != nil {
+		macSize = c.out.mac.Size()
+	}
+
+	payloadBytes := tcpMSSEstimate - recordHeaderLen - explicitIVLen
+	if c.out.cipher != nil {
+		switch ciph := c.out.cipher.(type) {
+		case cipher.Stream:
+			payloadBytes -= macSize
+		case cipher.AEAD:
+			payloadBytes -= ciph.Overhead()
+		case cbcMode:
+			blockSize := ciph.BlockSize()
+			// The payload must fit in a multiple of blockSize, with
+			// room for at least one padding byte.
+			payloadBytes = (payloadBytes & ^(blockSize - 1)) - 1
+			// The MAC is appended before padding so affects the
+			// payload size directly.
+			payloadBytes -= macSize
+		default:
+			panic("unknown cipher type")
+		}
+	}
+
+	// Allow packet growth in arithmetic progression up to max.
+	pkt := c.packetsSent
+	c.packetsSent++
+	if pkt > 1000 {
+		return maxPlaintext // avoid overflow in multiply below
+	}
+
+	n := payloadBytes * int(pkt+1)
+	if n > maxPlaintext {
+		n = maxPlaintext
+	}
+	return n
+}
+
 // c.out.Mutex <= L.
-func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
+func (c *Conn) write(data []byte) (int, error) {
+	if c.buffering {
+		c.sendBuf = append(c.sendBuf, data...)
+		return len(data), nil
+	}
+
+	n, err := c.conn.Write(data)
+	c.bytesSent += int64(n)
+	return n, err
+}
+
+func (c *Conn) flush() (int, error) {
+	if len(c.sendBuf) == 0 {
+		return 0, nil
+	}
+
+	n, err := c.conn.Write(c.sendBuf)
+	c.bytesSent += int64(n)
+	c.sendBuf = nil
+	c.buffering = false
+	return n, err
+}
+
+// writeRecordLocked writes a TLS record with the given type and payload to the
+// connection and updates the record layer state.
+// c.out.Mutex <= L.
+func (c *Conn) writeRecordLocked(typ recordType, data []byte) (int, error) {
 	b := c.out.newBlock()
+	defer c.out.freeBlock(b)
+
+	var n int
 	for len(data) > 0 {
-		m := len(data)
-		if m > maxPlaintext {
-			m = maxPlaintext
-		}
 		explicitIVLen := 0
 		explicitIVIsSeq := false
 
@@ -742,6 +860,10 @@ func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
 				explicitIVIsSeq = true
 			}
 		}
+		m := len(data)
+		if maxPayload := c.maxPayloadSizeForWrite(typ, explicitIVLen); m > maxPayload {
+			m = maxPayload
+		}
 		b.resize(recordHeaderLen + explicitIVLen + m)
 		b.data[0] = byte(typ)
 		vers := c.vers
@@ -759,34 +881,37 @@ func (c *Conn) writeRecord(typ recordType, data []byte) (n int, err error) {
 			if explicitIVIsSeq {
 				copy(explicitIV, c.out.seq[:])
 			} else {
-				if _, err = io.ReadFull(c.config.rand(), explicitIV); err != nil {
-					break
+				if _, err := io.ReadFull(c.config.rand(), explicitIV); err != nil {
+					return n, err
 				}
 			}
 		}
 		copy(b.data[recordHeaderLen+explicitIVLen:], data)
 		c.out.encrypt(b, explicitIVLen)
-		_, err = c.conn.Write(b.data)
-		if err != nil {
-			break
+		if _, err := c.write(b.data); err != nil {
+			return n, err
 		}
 		n += m
 		data = data[m:]
 	}
-	c.out.freeBlock(b)
 
 	if typ == recordTypeChangeCipherSpec {
-		err = c.out.changeCipherSpec()
-		if err != nil {
-			// Cannot call sendAlert directly,
-			// because we already hold c.out.Mutex.
-			c.tmp[0] = alertLevelError
-			c.tmp[1] = byte(err.(alert))
-			c.writeRecord(recordTypeAlert, c.tmp[0:2])
-			return n, c.out.setErrorLocked(&net.OpError{Op: "local error", Err: err})
+		if err := c.out.changeCipherSpec(); err != nil {
+			return n, c.sendAlertLocked(err.(alert))
 		}
 	}
-	return
+
+	return n, nil
+}
+
+// writeRecord writes a TLS record with the given type and payload to the
+// connection and updates the record layer state.
+// L < c.out.Mutex.
+func (c *Conn) writeRecord(typ recordType, data []byte) (int, error) {
+	c.out.Lock()
+	defer c.out.Unlock()
+
+	return c.writeRecordLocked(typ, data)
 }
 
 // readHandshake reads the next handshake message from
@@ -805,7 +930,8 @@ func (c *Conn) readHandshake() (interface{}, error) {
 	data := c.hand.Bytes()
 	n := int(data[1])<<16 | int(data[2])<<8 | int(data[3])
 	if n > maxHandshake {
-		return nil, c.in.setErrorLocked(c.sendAlert(alertInternalError))
+		c.sendAlertLocked(alertInternalError)
+		return nil, c.in.setErrorLocked(fmt.Errorf("tls: handshake message of length %d bytes exceeds maximum of %d bytes", n, maxHandshake))
 	}
 	for c.hand.Len() < 4+n {
 		if err := c.in.err; err != nil {
@@ -818,6 +944,8 @@ func (c *Conn) readHandshake() (interface{}, error) {
 	data = c.hand.Next(4 + n)
 	var m handshakeMessage
 	switch data[0] {
+	case typeHelloRequest:
+		m = new(helloRequestMsg)
 	case typeClientHello:
 		m = new(clientHelloMsg)
 	case typeServerHello:
@@ -861,7 +989,7 @@ func (c *Conn) readHandshake() (interface{}, error) {
 	return m, nil
 }
 
-var errClosed = errors.New("crypto/tls: use of closed connection")
+var errClosed = errors.New("tls: use of closed connection")
 
 // Write writes data to the connection.
 func (c *Conn) Write(b []byte) (int, error) {
@@ -904,7 +1032,7 @@ func (c *Conn) Write(b []byte) (int, error) {
 	var m int
 	if len(b) > 1 && c.vers <= VersionTLS10 {
 		if _, ok := c.out.cipher.(cipher.BlockMode); ok {
-			n, err := c.writeRecord(recordTypeApplicationData, b[:1])
+			n, err := c.writeRecordLocked(recordTypeApplicationData, b[:1])
 			if err != nil {
 				return n, c.out.setErrorLocked(err)
 			}
@@ -912,10 +1040,52 @@ func (c *Conn) Write(b []byte) (int, error) {
 		}
 	}
 
-	n, err := c.writeRecord(recordTypeApplicationData, b)
+	n, err := c.writeRecordLocked(recordTypeApplicationData, b)
 	return n + m, c.out.setErrorLocked(err)
 }
 
+// handleRenegotiation processes a HelloRequest handshake message.
+// c.in.Mutex <= L
+func (c *Conn) handleRenegotiation() error {
+	msg, err := c.readHandshake()
+	if err != nil {
+		return err
+	}
+
+	_, ok := msg.(*helloRequestMsg)
+	if !ok {
+		c.sendAlert(alertUnexpectedMessage)
+		return alertUnexpectedMessage
+	}
+
+	if !c.isClient {
+		return c.sendAlert(alertNoRenegotiation)
+	}
+
+	switch c.config.Renegotiation {
+	case RenegotiateNever:
+		return c.sendAlert(alertNoRenegotiation)
+	case RenegotiateOnceAsClient:
+		if c.handshakes > 1 {
+			return c.sendAlert(alertNoRenegotiation)
+		}
+	case RenegotiateFreelyAsClient:
+		// Ok.
+	default:
+		c.sendAlert(alertInternalError)
+		return errors.New("tls: unknown Renegotiation value")
+	}
+
+	c.handshakeMutex.Lock()
+	defer c.handshakeMutex.Unlock()
+
+	c.handshakeComplete = false
+	if c.handshakeErr = c.clientHandshake(); c.handshakeErr == nil {
+		c.handshakes++
+	}
+	return c.handshakeErr
+}
+
 // Read can be made to time out and return a net.Error with Timeout() == true
 // after a fixed time limit; see SetDeadline and SetReadDeadline.
 func (c *Conn) Read(b []byte) (n int, err error) {
@@ -940,6 +1110,13 @@ func (c *Conn) Read(b []byte) (n int, err error) {
 				// Soft error, like EAGAIN
 				return 0, err
 			}
+			if c.hand.Len() > 0 {
+				// We received handshake bytes, indicating the
+				// start of a renegotiation.
+				if err := c.handleRenegotiation(); err != nil {
+					return 0, err
+				}
+			}
 		}
 		if err := c.in.err; err != nil {
 			return 0, err
@@ -1020,13 +1197,35 @@ func (c *Conn) Close() error {
 // Most uses of this package need not call Handshake
 // explicitly: the first Read or Write will call it automatically.
 func (c *Conn) Handshake() error {
+	// c.handshakeErr and c.handshakeComplete are protected by
+	// c.handshakeMutex. In order to perform a handshake, we need to lock
+	// c.in also and c.handshakeMutex must be locked after c.in.
+	//
+	// However, if a Read() operation is hanging then it'll be holding the
+	// lock on c.in and so taking it here would cause all operations that
+	// need to check whether a handshake is pending (such as Write) to
+	// block.
+	//
+	// Thus we take c.handshakeMutex first and, if we find that a handshake
+	// is needed, then we unlock, acquire c.in and c.handshakeMutex in the
+	// correct order, and check again.
 	c.handshakeMutex.Lock()
 	defer c.handshakeMutex.Unlock()
-	if err := c.handshakeErr; err != nil {
-		return err
-	}
-	if c.handshakeComplete {
-		return nil
+
+	for i := 0; i < 2; i++ {
+		if i == 1 {
+			c.handshakeMutex.Unlock()
+			c.in.Lock()
+			defer c.in.Unlock()
+			c.handshakeMutex.Lock()
+		}
+
+		if err := c.handshakeErr; err != nil {
+			return err
+		}
+		if c.handshakeComplete {
+			return nil
+		}
 	}
 
 	if c.isClient {
@@ -1034,6 +1233,9 @@ func (c *Conn) Handshake() error {
 	} else {
 		c.handshakeErr = c.serverHandshake()
 	}
+	if c.handshakeErr == nil {
+		c.handshakes++
+	}
 	return c.handshakeErr
 }
 
@@ -1056,7 +1258,11 @@ func (c *Conn) ConnectionState() ConnectionState {
 		state.SignedCertificateTimestamps = c.scts
 		state.OCSPResponse = c.ocspResponse
 		if !c.didResume {
-			state.TLSUnique = c.firstFinished[:]
+			if c.clientFinishedIsFirst {
+				state.TLSUnique = c.clientFinished[:]
+			} else {
+				state.TLSUnique = c.serverFinished[:]
+			}
 		}
 	}
 
@@ -1073,7 +1279,7 @@ func (c *Conn) OCSPResponse() []byte {
 }
 
 // VerifyHostname checks that the peer certificate chain is valid for
-// connecting to host.  If so, it returns nil; if not, it returns an error
+// connecting to host. If so, it returns nil; if not, it returns an error
 // describing the problem.
 func (c *Conn) VerifyHostname(host string) error {
 	c.handshakeMutex.Lock()
diff --git a/libgo/go/crypto/tls/conn_test.go b/libgo/go/crypto/tls/conn_test.go
index ec802cad70f..5cff7e7cdd4 100644
--- a/libgo/go/crypto/tls/conn_test.go
+++ b/libgo/go/crypto/tls/conn_test.go
@@ -5,6 +5,9 @@
 package tls
 
 import (
+	"bytes"
+	"io"
+	"net"
 	"testing"
 )
 
@@ -116,3 +119,125 @@ func TestCertificateSelection(t *testing.T) {
 		t.Errorf("foo.bar.baz.example.com returned certificate %d, not 0", n)
 	}
 }
+
+// Run with multiple crypto configs to test the logic for computing TLS record overheads.
+func runDynamicRecordSizingTest(t *testing.T, config *Config) {
+	clientConn, serverConn := net.Pipe()
+
+	serverConfig := config.clone()
+	serverConfig.DynamicRecordSizingDisabled = false
+	tlsConn := Server(serverConn, serverConfig)
+
+	recordSizesChan := make(chan []int, 1)
+	go func() {
+		// This goroutine performs a TLS handshake over clientConn and
+		// then reads TLS records until EOF. It writes a slice that
+		// contains all the record sizes to recordSizesChan.
+		defer close(recordSizesChan)
+		defer clientConn.Close()
+
+		tlsConn := Client(clientConn, config)
+		if err := tlsConn.Handshake(); err != nil {
+			t.Errorf("Error from client handshake: %s", err)
+			return
+		}
+
+		var recordHeader [recordHeaderLen]byte
+		var record []byte
+		var recordSizes []int
+
+		for {
+			n, err := clientConn.Read(recordHeader[:])
+			if err == io.EOF {
+				break
+			}
+			if err != nil || n != len(recordHeader) {
+				t.Errorf("Error from client read: %s", err)
+				return
+			}
+
+			length := int(recordHeader[3])<<8 | int(recordHeader[4])
+			if len(record) < length {
+				record = make([]byte, length)
+			}
+
+			n, err = clientConn.Read(record[:length])
+			if err != nil || n != length {
+				t.Errorf("Error from client read: %s", err)
+				return
+			}
+
+			// The last record will be a close_notify alert, which
+			// we don't wish to record.
+			if recordType(recordHeader[0]) == recordTypeApplicationData {
+				recordSizes = append(recordSizes, recordHeaderLen+length)
+			}
+		}
+
+		recordSizesChan <- recordSizes
+	}()
+
+	if err := tlsConn.Handshake(); err != nil {
+		t.Fatalf("Error from server handshake: %s", err)
+	}
+
+	// The server writes these plaintexts in order.
+	plaintext := bytes.Join([][]byte{
+		bytes.Repeat([]byte("x"), recordSizeBoostThreshold),
+		bytes.Repeat([]byte("y"), maxPlaintext*2),
+		bytes.Repeat([]byte("z"), maxPlaintext),
+	}, nil)
+
+	if _, err := tlsConn.Write(plaintext); err != nil {
+		t.Fatalf("Error from server write: %s", err)
+	}
+	if err := tlsConn.Close(); err != nil {
+		t.Fatalf("Error from server close: %s", err)
+	}
+
+	recordSizes := <-recordSizesChan
+	if recordSizes == nil {
+		t.Fatalf("Client encountered an error")
+	}
+
+	// Drop the size of last record, which is likely to be truncated.
+	recordSizes = recordSizes[:len(recordSizes)-1]
+
+	// recordSizes should contain a series of records smaller than
+	// tcpMSSEstimate followed by some larger than maxPlaintext.
+	seenLargeRecord := false
+	for i, size := range recordSizes {
+		if !seenLargeRecord {
+			if size > (i+1)*tcpMSSEstimate {
+				t.Fatalf("Record #%d has size %d, which is too large too soon", i, size)
+			}
+			if size >= maxPlaintext {
+				seenLargeRecord = true
+			}
+		} else if size <= maxPlaintext {
+			t.Fatalf("Record #%d has size %d but should be full sized", i, size)
+		}
+	}
+
+	if !seenLargeRecord {
+		t.Fatalf("No large records observed")
+	}
+}
+
+func TestDynamicRecordSizingWithStreamCipher(t *testing.T) {
+	config := testConfig.clone()
+	config.CipherSuites = []uint16{TLS_RSA_WITH_RC4_128_SHA}
+	runDynamicRecordSizingTest(t, config)
+}
+
+func TestDynamicRecordSizingWithCBC(t *testing.T) {
+	config := testConfig.clone()
+	config.CipherSuites = []uint16{TLS_RSA_WITH_AES_256_CBC_SHA}
+	runDynamicRecordSizingTest(t, config)
+}
+
+func TestDynamicRecordSizingWithAEAD(t *testing.T) {
+	config := testConfig.clone()
+	config.CipherSuites = []uint16{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256}
+	runDynamicRecordSizingTest(t, config)
+}
diff --git a/libgo/go/crypto/tls/handshake_client.go b/libgo/go/crypto/tls/handshake_client.go
index 3c996acf878..f789e6f888f 100644
--- a/libgo/go/crypto/tls/handshake_client.go
+++ b/libgo/go/crypto/tls/handshake_client.go
@@ -16,6 +16,7 @@ import (
 	"io"
 	"net"
 	"strconv"
+	"strings"
 )
 
 type clientHandshakeState struct {
@@ -28,11 +29,16 @@ type clientHandshakeState struct {
 	session      *ClientSessionState
 }
 
+// c.out.Mutex <= L; c.handshakeMutex <= L.
 func (c *Conn) clientHandshake() error {
 	if c.config == nil {
 		c.config = defaultConfig()
 	}
 
+	// This may be a renegotiation handshake, in which case some fields
+	// need to be reset.
+	c.didResume = false
+
 	if len(c.config.ServerName) == 0 && !c.config.InsecureSkipVerify {
 		return errors.New("tls: either ServerName or InsecureSkipVerify must be specified in the tls.Config")
 	}
@@ -49,25 +55,22 @@ func (c *Conn) clientHandshake() error {
 		return errors.New("tls: NextProtos values too large")
 	}
 
-	sni := c.config.ServerName
-	// IP address literals are not permitted as SNI values. See
-	// https://tools.ietf.org/html/rfc6066#section-3.
-	if net.ParseIP(sni) != nil {
-		sni = ""
+	hello := &clientHelloMsg{
+		vers:                         c.config.maxVersion(),
+		compressionMethods:           []uint8{compressionNone},
+		random:                       make([]byte, 32),
+		ocspStapling:                 true,
+		scts:                         true,
+		serverName:                   hostnameInSNI(c.config.ServerName),
+		supportedCurves:              c.config.curvePreferences(),
+		supportedPoints:              []uint8{pointFormatUncompressed},
+		nextProtoNeg:                 len(c.config.NextProtos) > 0,
+		secureRenegotiationSupported: true,
+		alpnProtocols:                c.config.NextProtos,
 	}
 
-	hello := &clientHelloMsg{
-		vers:                c.config.maxVersion(),
-		compressionMethods:  []uint8{compressionNone},
-		random:              make([]byte, 32),
-		ocspStapling:        true,
-		scts:                true,
-		serverName:          sni,
-		supportedCurves:     c.config.curvePreferences(),
-		supportedPoints:     []uint8{pointFormatUncompressed},
-		nextProtoNeg:        len(c.config.NextProtos) > 0,
-		secureRenegotiation: true,
-		alpnProtocols:       c.config.NextProtos,
+	if c.handshakes > 0 {
+		hello.secureRenegotiation = c.clientFinished[:]
 	}
 
 	possibleCipherSuites := c.config.cipherSuites()
@@ -108,7 +111,12 @@ NextCipherSuite:
 
 	if sessionCache != nil {
 		hello.ticketSupported = true
+	}
 
+	// Session resumption is not allowed if renegotiating because
+	// renegotiation is primarily used to allow a client to send a client
+	// certificate, which would be skipped if session resumption occured.
+	if sessionCache != nil && c.handshakes == 0 {
 		// Try to resume a previously negotiated TLS session, if
 		// available.
 		cacheKey = clientSessionCacheKey(c.conn.RemoteAddr(), c.config)
@@ -144,7 +152,9 @@ NextCipherSuite:
 		}
 	}
 
-	c.writeRecord(recordTypeHandshake, hello.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, hello.marshal()); err != nil {
+		return err
+	}
 
 	msg, err := c.readHandshake()
 	if err != nil {
@@ -196,6 +206,7 @@ NextCipherSuite:
 	hs.finishedHash.Write(hs.hello.marshal())
 	hs.finishedHash.Write(hs.serverHello.marshal())
 
+	c.buffering = true
 	if isResume {
 		if err := hs.establishKeys(); err != nil {
 			return err
@@ -203,10 +214,14 @@ NextCipherSuite:
 		if err := hs.readSessionTicket(); err != nil {
 			return err
 		}
-		if err := hs.readFinished(c.firstFinished[:]); err != nil {
+		if err := hs.readFinished(c.serverFinished[:]); err != nil {
+			return err
+		}
+		c.clientFinishedIsFirst = false
+		if err := hs.sendFinished(c.clientFinished[:]); err != nil {
 			return err
 		}
-		if err := hs.sendFinished(nil); err != nil {
+		if _, err := c.flush(); err != nil {
 			return err
 		}
 	} else {
@@ -216,13 +231,17 @@ NextCipherSuite:
 		if err := hs.establishKeys(); err != nil {
 			return err
 		}
-		if err := hs.sendFinished(c.firstFinished[:]); err != nil {
+		if err := hs.sendFinished(c.clientFinished[:]); err != nil {
 			return err
 		}
+		if _, err := c.flush(); err != nil {
+			return err
+		}
+		c.clientFinishedIsFirst = true
 		if err := hs.readSessionTicket(); err != nil {
 			return err
 		}
-		if err := hs.readFinished(nil); err != nil {
+		if err := hs.readFinished(c.serverFinished[:]); err != nil {
 			return err
 		}
 	}
@@ -251,47 +270,62 @@ func (hs *clientHandshakeState) doFullHandshake() error {
 	}
 	hs.finishedHash.Write(certMsg.marshal())
 
-	certs := make([]*x509.Certificate, len(certMsg.certificates))
-	for i, asn1Data := range certMsg.certificates {
-		cert, err := x509.ParseCertificate(asn1Data)
-		if err != nil {
-			c.sendAlert(alertBadCertificate)
-			return errors.New("tls: failed to parse certificate from server: " + err.Error())
+	if c.handshakes == 0 {
+		// If this is the first handshake on a connection, process and
+		// (optionally) verify the server's certificates.
+		certs := make([]*x509.Certificate, len(certMsg.certificates))
+		for i, asn1Data := range certMsg.certificates {
+			cert, err := x509.ParseCertificate(asn1Data)
+			if err != nil {
+				c.sendAlert(alertBadCertificate)
+				return errors.New("tls: failed to parse certificate from server: " + err.Error())
+			}
+			certs[i] = cert
 		}
-		certs[i] = cert
-	}
 
-	if !c.config.InsecureSkipVerify {
-		opts := x509.VerifyOptions{
-			Roots:         c.config.RootCAs,
-			CurrentTime:   c.config.time(),
-			DNSName:       c.config.ServerName,
-			Intermediates: x509.NewCertPool(),
-		}
+		if !c.config.InsecureSkipVerify {
+			opts := x509.VerifyOptions{
+				Roots:         c.config.RootCAs,
+				CurrentTime:   c.config.time(),
+				DNSName:       c.config.ServerName,
+				Intermediates: x509.NewCertPool(),
+			}
 
-		for i, cert := range certs {
-			if i == 0 {
-				continue
+			for i, cert := range certs {
+				if i == 0 {
+					continue
+				}
+				opts.Intermediates.AddCert(cert)
+			}
+			c.verifiedChains, err = certs[0].Verify(opts)
+			if err != nil {
+				c.sendAlert(alertBadCertificate)
+				return err
 			}
-			opts.Intermediates.AddCert(cert)
 		}
-		c.verifiedChains, err = certs[0].Verify(opts)
-		if err != nil {
-			c.sendAlert(alertBadCertificate)
-			return err
+
+		switch certs[0].PublicKey.(type) {
+		case *rsa.PublicKey, *ecdsa.PublicKey:
+			break
+		default:
+			c.sendAlert(alertUnsupportedCertificate)
+			return fmt.Errorf("tls: server's certificate contains an unsupported type of public key: %T", certs[0].PublicKey)
 		}
-	}
 
-	switch certs[0].PublicKey.(type) {
-	case *rsa.PublicKey, *ecdsa.PublicKey:
-		break
-	default:
-		c.sendAlert(alertUnsupportedCertificate)
-		return fmt.Errorf("tls: server's certificate contains an unsupported type of public key: %T", certs[0].PublicKey)
+		c.peerCertificates = certs
+	} else {
+		// This is a renegotiation handshake. We require that the
+		// server's identity (i.e. leaf certificate) is unchanged and
+		// thus any previous trust decision is still valid.
+		//
+		// See https://mitls.org/pages/attacks/3SHAKE for the
+		// motivation behind this requirement.
+		if !bytes.Equal(c.peerCertificates[0].Raw, certMsg.certificates[0]) {
+			c.sendAlert(alertBadCertificate)
+			return errors.New("tls: server's identity changed during renegotiation")
+		}
 	}
 
-	c.peerCertificates = certs
-
 	if hs.serverHello.ocspStapling {
 		msg, err = c.readHandshake()
 		if err != nil {
@@ -319,7 +353,7 @@ func (hs *clientHandshakeState) doFullHandshake() error {
 	skx, ok := msg.(*serverKeyExchangeMsg)
 	if ok {
 		hs.finishedHash.Write(skx.marshal())
-		err = keyAgreement.processServerKeyExchange(c.config, hs.hello, hs.serverHello, certs[0], skx)
+		err = keyAgreement.processServerKeyExchange(c.config, hs.hello, hs.serverHello, c.peerCertificates[0], skx)
 		if err != nil {
 			c.sendAlert(alertUnexpectedMessage)
 			return err
@@ -425,17 +459,21 @@ func (hs *clientHandshakeState) doFullHandshake() error {
 			certMsg.certificates = chainToSend.Certificate
 		}
 		hs.finishedHash.Write(certMsg.marshal())
-		c.writeRecord(recordTypeHandshake, certMsg.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
+			return err
+		}
 	}
 
-	preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, certs[0])
+	preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, c.peerCertificates[0])
 	if err != nil {
 		c.sendAlert(alertInternalError)
 		return err
 	}
 	if ckx != nil {
 		hs.finishedHash.Write(ckx.marshal())
-		c.writeRecord(recordTypeHandshake, ckx.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, ckx.marshal()); err != nil {
+			return err
+		}
 	}
 
 	if chainToSend != nil {
@@ -477,7 +515,9 @@ func (hs *clientHandshakeState) doFullHandshake() error {
 		}
 
 		hs.finishedHash.Write(certVerify.marshal())
-		c.writeRecord(recordTypeHandshake, certVerify.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, certVerify.marshal()); err != nil {
+			return err
+		}
 	}
 
 	hs.masterSecret = masterFromPreMasterSecret(c.vers, hs.suite, preMasterSecret, hs.hello.random, hs.serverHello.random)
@@ -524,6 +564,24 @@ func (hs *clientHandshakeState) processServerHello() (bool, error) {
 		return false, errors.New("tls: server selected unsupported compression format")
 	}
 
+	if c.handshakes == 0 && hs.serverHello.secureRenegotiationSupported {
+		c.secureRenegotiation = true
+		if len(hs.serverHello.secureRenegotiation) != 0 {
+			c.sendAlert(alertHandshakeFailure)
+			return false, errors.New("tls: initial handshake had non-empty renegotiation extension")
+		}
+	}
+
+	if c.handshakes > 0 && c.secureRenegotiation {
+		var expectedSecureRenegotiation [24]byte
+		copy(expectedSecureRenegotiation[:], c.clientFinished[:])
+		copy(expectedSecureRenegotiation[12:], c.serverFinished[:])
+		if !bytes.Equal(hs.serverHello.secureRenegotiation, expectedSecureRenegotiation[:]) {
+			c.sendAlert(alertHandshakeFailure)
+			return false, errors.New("tls: incorrect renegotiation extension contents")
+		}
+	}
+
 	clientDidNPN := hs.hello.nextProtoNeg
 	clientDidALPN := len(hs.hello.alpnProtocols) > 0
 	serverHasNPN := hs.serverHello.nextProtoNeg
@@ -531,17 +589,17 @@ func (hs *clientHandshakeState) processServerHello() (bool, error) {
 
 	if !clientDidNPN && serverHasNPN {
 		c.sendAlert(alertHandshakeFailure)
-		return false, errors.New("server advertised unrequested NPN extension")
+		return false, errors.New("tls: server advertised unrequested NPN extension")
 	}
 
 	if !clientDidALPN && serverHasALPN {
 		c.sendAlert(alertHandshakeFailure)
-		return false, errors.New("server advertised unrequested ALPN extension")
+		return false, errors.New("tls: server advertised unrequested ALPN extension")
 	}
 
 	if serverHasNPN && serverHasALPN {
 		c.sendAlert(alertHandshakeFailure)
-		return false, errors.New("server advertised both NPN and ALPN extensions")
+		return false, errors.New("tls: server advertised both NPN and ALPN extensions")
 	}
 
 	if serverHasALPN {
@@ -550,22 +608,33 @@ func (hs *clientHandshakeState) processServerHello() (bool, error) {
 	}
 	c.scts = hs.serverHello.scts
 
-	if hs.serverResumedSession() {
-		// Restore masterSecret and peerCerts from previous state
-		hs.masterSecret = hs.session.masterSecret
-		c.peerCertificates = hs.session.serverCertificates
-		c.verifiedChains = hs.session.verifiedChains
-		return true, nil
+	if !hs.serverResumedSession() {
+		return false, nil
+	}
+
+	if hs.session.vers != c.vers {
+		c.sendAlert(alertHandshakeFailure)
+		return false, errors.New("tls: server resumed a session with a different version")
+	}
+
+	if hs.session.cipherSuite != hs.suite.id {
+		c.sendAlert(alertHandshakeFailure)
+		return false, errors.New("tls: server resumed a session with a different cipher suite")
 	}
-	return false, nil
+
+	// Restore masterSecret and peerCerts from previous state
+	hs.masterSecret = hs.session.masterSecret
+	c.peerCertificates = hs.session.serverCertificates
+	c.verifiedChains = hs.session.verifiedChains
+	return true, nil
 }
 
 func (hs *clientHandshakeState) readFinished(out []byte) error {
 	c := hs.c
 
 	c.readRecord(recordTypeChangeCipherSpec)
-	if err := c.in.error(); err != nil {
-		return err
+	if c.in.err != nil {
+		return c.in.err
 	}
 
 	msg, err := c.readHandshake()
@@ -621,7 +690,9 @@ func (hs *clientHandshakeState) readSessionTicket() error {
 func (hs *clientHandshakeState) sendFinished(out []byte) error {
 	c := hs.c
 
-	c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
+	if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil {
+		return err
+	}
 	if hs.serverHello.nextProtoNeg {
 		nextProto := new(nextProtoMsg)
 		proto, fallback := mutualProtocol(c.config.NextProtos, hs.serverHello.nextProtos)
@@ -630,13 +701,17 @@ func (hs *clientHandshakeState) sendFinished(out []byte) error {
 		c.clientProtocolFallback = fallback
 
 		hs.finishedHash.Write(nextProto.marshal())
-		c.writeRecord(recordTypeHandshake, nextProto.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, nextProto.marshal()); err != nil {
+			return err
+		}
 	}
 
 	finished := new(finishedMsg)
 	finished.verifyData = hs.finishedHash.clientSum(hs.masterSecret)
 	hs.finishedHash.Write(finished.marshal())
-	c.writeRecord(recordTypeHandshake, finished.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil {
+		return err
+	}
 	copy(out, finished.verifyData)
 	return nil
 }
@@ -665,3 +740,23 @@ func mutualProtocol(protos, preferenceProtos []string) (string, bool) {
 
 	return protos[0], true
 }
+
+// hostnameInSNI converts name into an approriate hostname for SNI.
+// Literal IP addresses and absolute FQDNs are not permitted as SNI values.
+// See https://tools.ietf.org/html/rfc6066#section-3.
+func hostnameInSNI(name string) string {
+	host := name
+	if len(host) > 0 && host[0] == '[' && host[len(host)-1] == ']' {
+		host = host[1 : len(host)-1]
+	}
+	if i := strings.LastIndex(host, "%"); i > 0 {
+		host = host[:i]
+	}
+	if net.ParseIP(host) != nil {
+		return ""
+	}
+	if len(name) > 0 && name[len(name)-1] == '.' {
+		name = name[:len(name)-1]
+	}
+	return name
+}
diff --git a/libgo/go/crypto/tls/handshake_client_test.go b/libgo/go/crypto/tls/handshake_client_test.go
index f78cc469355..ce987f11c46 100644
--- a/libgo/go/crypto/tls/handshake_client_test.go
+++ b/libgo/go/crypto/tls/handshake_client_test.go
@@ -12,6 +12,7 @@ import (
 	"encoding/base64"
 	"encoding/binary"
 	"encoding/pem"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -27,14 +28,80 @@ import (
 // Note: see comment in handshake_test.go for details of how the reference
 // tests work.
 
-// blockingSource is an io.Reader that blocks a Read call until it's closed.
-type blockingSource chan bool
+// opensslInputEvent enumerates possible inputs that can be sent to an `openssl
+// s_client` process.
+type opensslInputEvent int
+
+const (
+	// opensslRenegotiate causes OpenSSL to request a renegotiation of the
+	// connection.
+	opensslRenegotiate opensslInputEvent = iota
+
+	// opensslSendBanner causes OpenSSL to send the contents of
+	// opensslSentinel on the connection.
+	opensslSendSentinel
+)
+
+const opensslSentinel = "SENTINEL\n"
+
+type opensslInput chan opensslInputEvent
+
+func (i opensslInput) Read(buf []byte) (n int, err error) {
+	for event := range i {
+		switch event {
+		case opensslRenegotiate:
+			return copy(buf, []byte("R\n")), nil
+		case opensslSendSentinel:
+			return copy(buf, []byte(opensslSentinel)), nil
+		default:
+			panic("unknown event")
+		}
+	}
 
-func (b blockingSource) Read([]byte) (n int, err error) {
-	<-b
 	return 0, io.EOF
 }
 
+// opensslOutputSink is an io.Writer that receives the stdout and stderr from
+// an `openssl` process and sends a value to handshakeComplete when it sees a
+// log message from a completed server handshake.
+type opensslOutputSink struct {
+	handshakeComplete chan struct{}
+	all               []byte
+	line              []byte
+}
+
+func newOpensslOutputSink() *opensslOutputSink {
+	return &opensslOutputSink{make(chan struct{}), nil, nil}
+}
+
+// opensslEndOfHandshake is a message that the “openssl s_server” tool will
+// print when a handshake completes if run with “-state”.
+const opensslEndOfHandshake = "SSL_accept:SSLv3 write finished A"
+
+func (o *opensslOutputSink) Write(data []byte) (n int, err error) {
+	o.line = append(o.line, data...)
+	o.all = append(o.all, data...)
+
+	for {
+		i := bytes.Index(o.line, []byte{'\n'})
+		if i < 0 {
+			break
+		}
+
+		if bytes.Equal([]byte(opensslEndOfHandshake), o.line[:i]) {
+			o.handshakeComplete <- struct{}{}
+		}
+		o.line = o.line[i+1:]
+	}
+
+	return len(data), nil
+}
+
+func (o *opensslOutputSink) WriteTo(w io.Writer) (int64, error) {
+	n, err := w.Write(o.all)
+	return int64(n), err
+}
+
 // clientTest represents a test of the TLS client handshake against a reference
 // implementation.
 type clientTest struct {
@@ -60,15 +127,25 @@ type clientTest struct {
 	// ConnectionState of the resulting connection. It returns a non-nil
 	// error if the ConnectionState is unacceptable.
 	validate func(ConnectionState) error
+	// numRenegotiations is the number of times that the connection will be
+	// renegotiated.
+	numRenegotiations int
+	// renegotiationExpectedToFail, if not zero, is the number of the
+	// renegotiation attempt that is expected to fail.
+	renegotiationExpectedToFail int
+	// checkRenegotiationError, if not nil, is called with any error
+	// arising from renegotiation. It can map expected errors to nil to
+	// ignore them.
+	checkRenegotiationError func(renegotiationNum int, err error) error
 }
 
 var defaultServerCommand = []string{"openssl", "s_server"}
 
 // connFromCommand starts the reference server process, connects to it and
-// returns a recordingConn for the connection. The stdin return value is a
-// blockingSource for the stdin of the child process. It must be closed before
+// returns a recordingConn for the connection. The stdin return value is an
+// opensslInput for the stdin of the child process. It must be closed before
 // Waiting for child.
-func (test *clientTest) connFromCommand() (conn *recordingConn, child *exec.Cmd, stdin blockingSource, err error) {
+func (test *clientTest) connFromCommand() (conn *recordingConn, child *exec.Cmd, stdin opensslInput, stdout *opensslOutputSink, err error) {
 	cert := testRSACertificate
 	if len(test.cert) > 0 {
 		cert = test.cert
@@ -131,14 +208,28 @@ func (test *clientTest) connFromCommand() (conn *recordingConn, child *exec.Cmd,
 		command = append(command, "-serverinfo", serverInfoPath)
 	}
 
+	if test.numRenegotiations > 0 {
+		found := false
+		for _, flag := range command[1:] {
+			if flag == "-state" {
+				found = true
+				break
+			}
+		}
+
+		if !found {
+			panic("-state flag missing to OpenSSL. You need this if testing renegotiation")
+		}
+	}
+
 	cmd := exec.Command(command[0], command[1:]...)
-	stdin = blockingSource(make(chan bool))
+	stdin = opensslInput(make(chan opensslInputEvent))
 	cmd.Stdin = stdin
-	var out bytes.Buffer
-	cmd.Stdout = &out
-	cmd.Stderr = &out
+	out := newOpensslOutputSink()
+	cmd.Stdout = out
+	cmd.Stderr = out
 	if err := cmd.Start(); err != nil {
-		return nil, nil, nil, err
+		return nil, nil, nil, nil, err
 	}
 
 	// OpenSSL does print an "ACCEPT" banner, but it does so *before*
@@ -160,14 +251,14 @@ func (test *clientTest) connFromCommand() (conn *recordingConn, child *exec.Cmd,
 		close(stdin)
 		out.WriteTo(os.Stdout)
 		cmd.Process.Kill()
-		return nil, nil, nil, cmd.Wait()
+		return nil, nil, nil, nil, cmd.Wait()
 	}
 
 	record := &recordingConn{
 		Conn: tcpConn,
 	}
 
-	return record, cmd, stdin, nil
+	return record, cmd, stdin, out, nil
 }
 
 func (test *clientTest) dataPath() string {
@@ -187,11 +278,12 @@ func (test *clientTest) run(t *testing.T, write bool) {
 	var clientConn, serverConn net.Conn
 	var recordingConn *recordingConn
 	var childProcess *exec.Cmd
-	var stdin blockingSource
+	var stdin opensslInput
+	var stdout *opensslOutputSink
 
 	if write {
 		var err error
-		recordingConn, childProcess, stdin, err = test.connFromCommand()
+		recordingConn, childProcess, stdin, stdout, err = test.connFromCommand()
 		if err != nil {
 			t.Fatalf("Failed to start subcommand: %s", err)
 		}
@@ -208,17 +300,77 @@ func (test *clientTest) run(t *testing.T, write bool) {
 
 	doneChan := make(chan bool)
 	go func() {
+		defer func() { doneChan <- true }()
+		defer clientConn.Close()
+		defer client.Close()
+
 		if _, err := client.Write([]byte("hello\n")); err != nil {
 			t.Errorf("Client.Write failed: %s", err)
+			return
 		}
+
+		for i := 1; i <= test.numRenegotiations; i++ {
+			// The initial handshake will generate a
+			// handshakeComplete signal which needs to be quashed.
+			if i == 1 && write {
+				<-stdout.handshakeComplete
+			}
+
+			// OpenSSL will try to interleave application data and
+			// a renegotiation if we send both concurrently.
+			// Therefore: ask OpensSSL to start a renegotiation, run
+			// a goroutine to call client.Read and thus process the
+			// renegotiation request, watch for OpenSSL's stdout to
+			// indicate that the handshake is complete and,
+			// finally, have OpenSSL write something to cause
+			// client.Read to complete.
+			if write {
+				stdin <- opensslRenegotiate
+			}
+
+			signalChan := make(chan struct{})
+
+			go func() {
+				defer func() { signalChan <- struct{}{} }()
+
+				buf := make([]byte, 256)
+				n, err := client.Read(buf)
+
+				if test.checkRenegotiationError != nil {
+					newErr := test.checkRenegotiationError(i, err)
+					if err != nil && newErr == nil {
+						return
+					}
+					err = newErr
+				}
+
+				if err != nil {
+					t.Errorf("Client.Read failed after renegotiation #%d: %s", i, err)
+					return
+				}
+
+				buf = buf[:n]
+				if !bytes.Equal([]byte(opensslSentinel), buf) {
+					t.Errorf("Client.Read returned %q, but wanted %q", string(buf), opensslSentinel)
+				}
+
+				if expected := i + 1; client.handshakes != expected {
+					t.Errorf("client should have recorded %d handshakes, but believes that %d have occured", expected, client.handshakes)
+				}
+			}()
+
+			if write && test.renegotiationExpectedToFail != i {
+				<-stdout.handshakeComplete
+				stdin <- opensslSendSentinel
+			}
+			<-signalChan
+		}
+
 		if test.validate != nil {
 			if err := test.validate(client.ConnectionState()); err != nil {
 				t.Errorf("validate callback returned error: %s", err)
 			}
 		}
-		client.Close()
-		clientConn.Close()
-		doneChan <- true
 	}()
 
 	if !write {
@@ -357,14 +509,14 @@ func TestHandshakeClientAES256GCMSHA384(t *testing.T) {
 }
 
 func TestHandshakeClientCertRSA(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	cert, _ := X509KeyPair([]byte(clientCertificatePEM), []byte(clientKeyPEM))
 	config.Certificates = []Certificate{cert}
 
 	test := &clientTest{
 		name:    "ClientCert-RSA-RSA",
 		command: []string{"openssl", "s_server", "-cipher", "RC4-SHA", "-verify", "1"},
-		config:  &config,
+		config:  config,
 	}
 
 	runClientTestTLS10(t, test)
@@ -373,7 +525,7 @@ func TestHandshakeClientCertRSA(t *testing.T) {
 	test = &clientTest{
 		name:    "ClientCert-RSA-ECDSA",
 		command: []string{"openssl", "s_server", "-cipher", "ECDHE-ECDSA-AES128-SHA", "-verify", "1"},
-		config:  &config,
+		config:  config,
 		cert:    testECDSACertificate,
 		key:     testECDSAPrivateKey,
 	}
@@ -384,7 +536,7 @@ func TestHandshakeClientCertRSA(t *testing.T) {
 	test = &clientTest{
 		name:    "ClientCert-RSA-AES256-GCM-SHA384",
 		command: []string{"openssl", "s_server", "-cipher", "ECDHE-RSA-AES256-GCM-SHA384", "-verify", "1"},
-		config:  &config,
+		config:  config,
 		cert:    testRSACertificate,
 		key:     testRSAPrivateKey,
 	}
@@ -393,14 +545,14 @@ func TestHandshakeClientCertRSA(t *testing.T) {
 }
 
 func TestHandshakeClientCertECDSA(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	cert, _ := X509KeyPair([]byte(clientECDSACertificatePEM), []byte(clientECDSAKeyPEM))
 	config.Certificates = []Certificate{cert}
 
 	test := &clientTest{
 		name:    "ClientCert-ECDSA-RSA",
 		command: []string{"openssl", "s_server", "-cipher", "RC4-SHA", "-verify", "1"},
-		config:  &config,
+		config:  config,
 	}
 
 	runClientTestTLS10(t, test)
@@ -409,7 +561,7 @@ func TestHandshakeClientCertECDSA(t *testing.T) {
 	test = &clientTest{
 		name:    "ClientCert-ECDSA-ECDSA",
 		command: []string{"openssl", "s_server", "-cipher", "ECDHE-ECDSA-AES128-SHA", "-verify", "1"},
-		config:  &config,
+		config:  config,
 		cert:    testECDSACertificate,
 		key:     testECDSAPrivateKey,
 	}
@@ -448,7 +600,7 @@ func TestClientResumption(t *testing.T) {
 			t.Fatalf("%s resumed: %v, expected: %v", test, hs.DidResume, didResume)
 		}
 		if didResume && (hs.PeerCertificates == nil || hs.VerifiedChains == nil) {
-			t.Fatalf("expected non-nil certificates after resumption. Got peerCertificates: %#v, verifedCertificates: %#v", hs.PeerCertificates, hs.VerifiedChains)
+			t.Fatalf("expected non-nil certificates after resumption. Got peerCertificates: %#v, verifiedCertificates: %#v", hs.PeerCertificates, hs.VerifiedChains)
 		}
 	}
 
@@ -539,7 +691,7 @@ func TestLRUClientSessionCache(t *testing.T) {
 }
 
 func TestHandshakeClientALPNMatch(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	config.NextProtos = []string{"proto2", "proto1"}
 
 	test := &clientTest{
@@ -547,7 +699,7 @@ func TestHandshakeClientALPNMatch(t *testing.T) {
 		// Note that this needs OpenSSL 1.0.2 because that is the first
 		// version that supports the -alpn flag.
 		command: []string{"openssl", "s_server", "-alpn", "proto1,proto2"},
-		config:  &config,
+		config:  config,
 		validate: func(state ConnectionState) error {
 			// The server's preferences should override the client.
 			if state.NegotiatedProtocol != "proto1" {
@@ -560,7 +712,7 @@ func TestHandshakeClientALPNMatch(t *testing.T) {
 }
 
 func TestHandshakeClientALPNNoMatch(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	config.NextProtos = []string{"proto3"}
 
 	test := &clientTest{
@@ -568,7 +720,7 @@ func TestHandshakeClientALPNNoMatch(t *testing.T) {
 		// Note that this needs OpenSSL 1.0.2 because that is the first
 		// version that supports the -alpn flag.
 		command: []string{"openssl", "s_server", "-alpn", "proto1,proto2"},
-		config:  &config,
+		config:  config,
 		validate: func(state ConnectionState) error {
 			// There's no overlap so OpenSSL will not select a protocol.
 			if state.NegotiatedProtocol != "" {
@@ -584,7 +736,7 @@ func TestHandshakeClientALPNNoMatch(t *testing.T) {
 const sctsBase64 = "ABIBaQFnAHUApLkJkLQYWBSHuxOizGdwCjw1mAT5G9+443fNDsgN3BAAAAFHl5nuFgAABAMARjBEAiAcS4JdlW5nW9sElUv2zvQyPoZ6ejKrGGB03gjaBZFMLwIgc1Qbbn+hsH0RvObzhS+XZhr3iuQQJY8S9G85D9KeGPAAdgBo9pj4H2SCvjqM7rkoHUz8cVFdZ5PURNEKZ6y7T0/7xAAAAUeX4bVwAAAEAwBHMEUCIDIhFDgG2HIuADBkGuLobU5a4dlCHoJLliWJ1SYT05z6AiEAjxIoZFFPRNWMGGIjskOTMwXzQ1Wh2e7NxXE1kd1J0QsAdgDuS723dc5guuFCaR+r4Z5mow9+X7By2IMAxHuJeqj9ywAAAUhcZIqHAAAEAwBHMEUCICmJ1rBT09LpkbzxtUC+Hi7nXLR0J+2PmwLp+sJMuqK+AiEAr0NkUnEVKVhAkccIFpYDqHOlZaBsuEhWWrYpg2RtKp0="
 
 func TestHandshakClientSCTs(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 
 	scts, err := base64.StdEncoding.DecodeString(sctsBase64)
 	if err != nil {
@@ -596,7 +748,7 @@ func TestHandshakClientSCTs(t *testing.T) {
 		// Note that this needs OpenSSL 1.0.2 because that is the first
 		// version that supports the -serverinfo flag.
 		command:    []string{"openssl", "s_server"},
-		config:     &config,
+		config:     config,
 		extensions: [][]byte{scts},
 		validate: func(state ConnectionState) error {
 			expectedSCTs := [][]byte{
@@ -618,14 +770,113 @@ func TestHandshakClientSCTs(t *testing.T) {
 	runClientTestTLS12(t, test)
 }
 
-func TestNoIPAddressesInSNI(t *testing.T) {
-	for _, ipLiteral := range []string{"1.2.3.4", "::1"} {
+func TestRenegotiationRejected(t *testing.T) {
+	config := testConfig.clone()
+	test := &clientTest{
+		name:                        "RenegotiationRejected",
+		command:                     []string{"openssl", "s_server", "-state"},
+		config:                      config,
+		numRenegotiations:           1,
+		renegotiationExpectedToFail: 1,
+		checkRenegotiationError: func(renegotiationNum int, err error) error {
+			if err == nil {
+				return errors.New("expected error from renegotiation but got nil")
+			}
+			if !strings.Contains(err.Error(), "no renegotiation") {
+				return fmt.Errorf("expected renegotiation to be rejected but got %q", err)
+			}
+			return nil
+		},
+	}
+
+	runClientTestTLS12(t, test)
+}
+
+func TestRenegotiateOnce(t *testing.T) {
+	config := testConfig.clone()
+	config.Renegotiation = RenegotiateOnceAsClient
+
+	test := &clientTest{
+		name:              "RenegotiateOnce",
+		command:           []string{"openssl", "s_server", "-state"},
+		config:            config,
+		numRenegotiations: 1,
+	}
+
+	runClientTestTLS12(t, test)
+}
+
+func TestRenegotiateTwice(t *testing.T) {
+	config := testConfig.clone()
+	config.Renegotiation = RenegotiateFreelyAsClient
+
+	test := &clientTest{
+		name:              "RenegotiateTwice",
+		command:           []string{"openssl", "s_server", "-state"},
+		config:            config,
+		numRenegotiations: 2,
+	}
+
+	runClientTestTLS12(t, test)
+}
+
+func TestRenegotiateTwiceRejected(t *testing.T) {
+	config := testConfig.clone()
+	config.Renegotiation = RenegotiateOnceAsClient
+
+	test := &clientTest{
+		name:                        "RenegotiateTwiceRejected",
+		command:                     []string{"openssl", "s_server", "-state"},
+		config:                      config,
+		numRenegotiations:           2,
+		renegotiationExpectedToFail: 2,
+		checkRenegotiationError: func(renegotiationNum int, err error) error {
+			if renegotiationNum == 1 {
+				return err
+			}
+
+			if err == nil {
+				return errors.New("expected error from renegotiation but got nil")
+			}
+			if !strings.Contains(err.Error(), "no renegotiation") {
+				return fmt.Errorf("expected renegotiation to be rejected but got %q", err)
+			}
+			return nil
+		},
+	}
+
+	runClientTestTLS12(t, test)
+}
+
+var hostnameInSNITests = []struct {
+	in, out string
+}{
+	// Opaque string
+	{"", ""},
+	{"localhost", "localhost"},
+	{"foo, bar, baz and qux", "foo, bar, baz and qux"},
+
+	// DNS hostname
+	{"golang.org", "golang.org"},
+	{"golang.org.", "golang.org"},
+
+	// Literal IPv4 address
+	{"1.2.3.4", ""},
+
+	// Literal IPv6 address
+	{"::1", ""},
+	{"::1%lo0", ""}, // with zone identifier
+	{"[::1]", ""},   // as per RFC 5952 we allow the [] style as IPv6 literal
+	{"[::1%lo0]", ""},
+}
+
+func TestHostnameInSNI(t *testing.T) {
+	for _, tt := range hostnameInSNITests {
 		c, s := net.Pipe()
 
-		go func() {
-			client := Client(c, &Config{ServerName: ipLiteral})
-			client.Handshake()
-		}()
+		go func(host string) {
+			Client(c, &Config{ServerName: host, InsecureSkipVerify: true}).Handshake()
+		}(tt.in)
 
 		var header [5]byte
 		if _, err := io.ReadFull(s, header[:]); err != nil {
@@ -637,10 +888,20 @@ func TestNoIPAddressesInSNI(t *testing.T) {
 		if _, err := io.ReadFull(s, record[:]); err != nil {
 			t.Fatal(err)
 		}
+
+		c.Close()
 		s.Close()
 
-		if bytes.Index(record, []byte(ipLiteral)) != -1 {
-			t.Errorf("IP literal %q found in ClientHello: %x", ipLiteral, record)
+		var m clientHelloMsg
+		if !m.unmarshal(record) {
+			t.Errorf("unmarshaling ClientHello for %q failed", tt.in)
+			continue
+		}
+		if tt.in != tt.out && m.serverName == tt.in {
+			t.Errorf("prohibited %q found in ClientHello: %x", tt.in, record)
+		}
+		if m.serverName != tt.out {
+			t.Errorf("expected %q not found in ClientHello: %x", tt.out, record)
 		}
 	}
 }
@@ -694,3 +955,93 @@ func TestServerSelectingUnconfiguredCipherSuite(t *testing.T) {
 		t.Fatalf("Expected error about unconfigured cipher suite but got %q", err)
 	}
 }
+
+// brokenConn wraps a net.Conn and causes all Writes after a certain number to
+// fail with brokenConnErr.
+type brokenConn struct {
+	net.Conn
+
+	// breakAfter is the number of successful writes that will be allowed
+	// before all subsequent writes fail.
+	breakAfter int
+
+	// numWrites is the number of writes that have been done.
+	numWrites int
+}
+
+// brokenConnErr is the error that brokenConn returns once exhausted.
+var brokenConnErr = errors.New("too many writes to brokenConn")
+
+func (b *brokenConn) Write(data []byte) (int, error) {
+	if b.numWrites >= b.breakAfter {
+		return 0, brokenConnErr
+	}
+
+	b.numWrites++
+	return b.Conn.Write(data)
+}
+
+func TestFailedWrite(t *testing.T) {
+	// Test that a write error during the handshake is returned.
+	for _, breakAfter := range []int{0, 1} {
+		c, s := net.Pipe()
+		done := make(chan bool)
+
+		go func() {
+			Server(s, testConfig).Handshake()
+			s.Close()
+			done <- true
+		}()
+
+		brokenC := &brokenConn{Conn: c, breakAfter: breakAfter}
+		err := Client(brokenC, testConfig).Handshake()
+		if err != brokenConnErr {
+			t.Errorf("#%d: expected error from brokenConn but got %q", breakAfter, err)
+		}
+		brokenC.Close()
+
+		<-done
+	}
+}
+
+// writeCountingConn wraps a net.Conn and counts the number of Write calls.
+type writeCountingConn struct {
+	net.Conn
+
+	// numWrites is the number of writes that have been done.
+	numWrites int
+}
+
+func (wcc *writeCountingConn) Write(data []byte) (int, error) {
+	wcc.numWrites++
+	return wcc.Conn.Write(data)
+}
+
+func TestBuffering(t *testing.T) {
+	c, s := net.Pipe()
+	done := make(chan bool)
+
+	clientWCC := &writeCountingConn{Conn: c}
+	serverWCC := &writeCountingConn{Conn: s}
+
+	go func() {
+		Server(serverWCC, testConfig).Handshake()
+		serverWCC.Close()
+		done <- true
+	}()
+
+	err := Client(clientWCC, testConfig).Handshake()
+	if err != nil {
+		t.Fatal(err)
+	}
+	clientWCC.Close()
+	<-done
+
+	if n := clientWCC.numWrites; n != 2 {
+		t.Errorf("expected client handshake to complete with only two writes, but saw %d", n)
+	}
+
+	if n := serverWCC.numWrites; n != 2 {
+		t.Errorf("expected server handshake to complete with only two writes, but saw %d", n)
+	}
+}
diff --git a/libgo/go/crypto/tls/handshake_messages.go b/libgo/go/crypto/tls/handshake_messages.go
index 111ce53487a..ab8e60ae116 100644
--- a/libgo/go/crypto/tls/handshake_messages.go
+++ b/libgo/go/crypto/tls/handshake_messages.go
@@ -7,23 +7,24 @@ package tls
 import "bytes"
 
 type clientHelloMsg struct {
-	raw                 []byte
-	vers                uint16
-	random              []byte
-	sessionId           []byte
-	cipherSuites        []uint16
-	compressionMethods  []uint8
-	nextProtoNeg        bool
-	serverName          string
-	ocspStapling        bool
-	scts                bool
-	supportedCurves     []CurveID
-	supportedPoints     []uint8
-	ticketSupported     bool
-	sessionTicket       []uint8
-	signatureAndHashes  []signatureAndHash
-	secureRenegotiation bool
-	alpnProtocols       []string
+	raw                          []byte
+	vers                         uint16
+	random                       []byte
+	sessionId                    []byte
+	cipherSuites                 []uint16
+	compressionMethods           []uint8
+	nextProtoNeg                 bool
+	serverName                   string
+	ocspStapling                 bool
+	scts                         bool
+	supportedCurves              []CurveID
+	supportedPoints              []uint8
+	ticketSupported              bool
+	sessionTicket                []uint8
+	signatureAndHashes           []signatureAndHash
+	secureRenegotiation          []byte
+	secureRenegotiationSupported bool
+	alpnProtocols                []string
 }
 
 func (m *clientHelloMsg) equal(i interface{}) bool {
@@ -47,7 +48,8 @@ func (m *clientHelloMsg) equal(i interface{}) bool {
 		m.ticketSupported == m1.ticketSupported &&
 		bytes.Equal(m.sessionTicket, m1.sessionTicket) &&
 		eqSignatureAndHashes(m.signatureAndHashes, m1.signatureAndHashes) &&
-		m.secureRenegotiation == m1.secureRenegotiation &&
+		m.secureRenegotiationSupported == m1.secureRenegotiationSupported &&
+		bytes.Equal(m.secureRenegotiation, m1.secureRenegotiation) &&
 		eqStrings(m.alpnProtocols, m1.alpnProtocols)
 }
 
@@ -86,8 +88,8 @@ func (m *clientHelloMsg) marshal() []byte {
 		extensionsLength += 2 + 2*len(m.signatureAndHashes)
 		numExtensions++
 	}
-	if m.secureRenegotiation {
-		extensionsLength += 1
+	if m.secureRenegotiationSupported {
+		extensionsLength += 1 + len(m.secureRenegotiation)
 		numExtensions++
 	}
 	if len(m.alpnProtocols) > 0 {
@@ -214,7 +216,7 @@ func (m *clientHelloMsg) marshal() []byte {
 		z[4] = byte(l)
 		z = z[5:]
 		for _, pointFormat := range m.supportedPoints {
-			z[0] = byte(pointFormat)
+			z[0] = pointFormat
 			z = z[1:]
 		}
 	}
@@ -248,12 +250,15 @@ func (m *clientHelloMsg) marshal() []byte {
 			z = z[2:]
 		}
 	}
-	if m.secureRenegotiation {
+	if m.secureRenegotiationSupported {
 		z[0] = byte(extensionRenegotiationInfo >> 8)
 		z[1] = byte(extensionRenegotiationInfo & 0xff)
 		z[2] = 0
-		z[3] = 1
+		z[3] = byte(len(m.secureRenegotiation) + 1)
+		z[4] = byte(len(m.secureRenegotiation))
 		z = z[5:]
+		copy(z, m.secureRenegotiation)
+		z = z[len(m.secureRenegotiation):]
 	}
 	if len(m.alpnProtocols) > 0 {
 		z[0] = byte(extensionALPN >> 8)
@@ -316,7 +321,7 @@ func (m *clientHelloMsg) unmarshal(data []byte) bool {
 	for i := 0; i < numCipherSuites; i++ {
 		m.cipherSuites[i] = uint16(data[2+2*i])<<8 | uint16(data[3+2*i])
 		if m.cipherSuites[i] == scsvRenegotiation {
-			m.secureRenegotiation = true
+			m.secureRenegotiationSupported = true
 		}
 	}
 	data = data[2+cipherSuiteLen:]
@@ -448,10 +453,18 @@ func (m *clientHelloMsg) unmarshal(data []byte) bool {
 				d = d[2:]
 			}
 		case extensionRenegotiationInfo:
-			if length != 1 || data[0] != 0 {
+			if length == 0 {
+				return false
+			}
+			d := data[:length]
+			l := int(d[0])
+			d = d[1:]
+			if l != len(d) {
 				return false
 			}
-			m.secureRenegotiation = true
+
+			m.secureRenegotiation = d
+			m.secureRenegotiationSupported = true
 		case extensionALPN:
 			if length < 2 {
 				return false
@@ -483,19 +496,20 @@ func (m *clientHelloMsg) unmarshal(data []byte) bool {
 }
 
 type serverHelloMsg struct {
-	raw                 []byte
-	vers                uint16
-	random              []byte
-	sessionId           []byte
-	cipherSuite         uint16
-	compressionMethod   uint8
-	nextProtoNeg        bool
-	nextProtos          []string
-	ocspStapling        bool
-	scts                [][]byte
-	ticketSupported     bool
-	secureRenegotiation bool
-	alpnProtocol        string
+	raw                          []byte
+	vers                         uint16
+	random                       []byte
+	sessionId                    []byte
+	cipherSuite                  uint16
+	compressionMethod            uint8
+	nextProtoNeg                 bool
+	nextProtos                   []string
+	ocspStapling                 bool
+	scts                         [][]byte
+	ticketSupported              bool
+	secureRenegotiation          []byte
+	secureRenegotiationSupported bool
+	alpnProtocol                 string
 }
 
 func (m *serverHelloMsg) equal(i interface{}) bool {
@@ -523,7 +537,8 @@ func (m *serverHelloMsg) equal(i interface{}) bool {
 		eqStrings(m.nextProtos, m1.nextProtos) &&
 		m.ocspStapling == m1.ocspStapling &&
 		m.ticketSupported == m1.ticketSupported &&
-		m.secureRenegotiation == m1.secureRenegotiation &&
+		m.secureRenegotiationSupported == m1.secureRenegotiationSupported &&
+		bytes.Equal(m.secureRenegotiation, m1.secureRenegotiation) &&
 		m.alpnProtocol == m1.alpnProtocol
 }
 
@@ -551,8 +566,8 @@ func (m *serverHelloMsg) marshal() []byte {
 	if m.ticketSupported {
 		numExtensions++
 	}
-	if m.secureRenegotiation {
-		extensionsLength += 1
+	if m.secureRenegotiationSupported {
+		extensionsLength += 1 + len(m.secureRenegotiation)
 		numExtensions++
 	}
 	if alpnLen := len(m.alpnProtocol); alpnLen > 0 {
@@ -589,7 +604,7 @@ func (m *serverHelloMsg) marshal() []byte {
 	z := x[39+len(m.sessionId):]
 	z[0] = uint8(m.cipherSuite >> 8)
 	z[1] = uint8(m.cipherSuite)
-	z[2] = uint8(m.compressionMethod)
+	z[2] = m.compressionMethod
 
 	z = z[3:]
 	if numExtensions > 0 {
@@ -624,12 +639,15 @@ func (m *serverHelloMsg) marshal() []byte {
 		z[1] = byte(extensionSessionTicket)
 		z = z[4:]
 	}
-	if m.secureRenegotiation {
+	if m.secureRenegotiationSupported {
 		z[0] = byte(extensionRenegotiationInfo >> 8)
 		z[1] = byte(extensionRenegotiationInfo & 0xff)
 		z[2] = 0
-		z[3] = 1
+		z[3] = byte(len(m.secureRenegotiation) + 1)
+		z[4] = byte(len(m.secureRenegotiation))
 		z = z[5:]
+		copy(z, m.secureRenegotiation)
+		z = z[len(m.secureRenegotiation):]
 	}
 	if alpnLen := len(m.alpnProtocol); alpnLen > 0 {
 		z[0] = byte(extensionALPN >> 8)
@@ -744,10 +762,18 @@ func (m *serverHelloMsg) unmarshal(data []byte) bool {
 			}
 			m.ticketSupported = true
 		case extensionRenegotiationInfo:
-			if length != 1 || data[0] != 0 {
+			if length == 0 {
+				return false
+			}
+			d := data[:length]
+			l := int(d[0])
+			d = d[1:]
+			if l != len(d) {
 				return false
 			}
-			m.secureRenegotiation = true
+
+			m.secureRenegotiation = d
+			m.secureRenegotiationSupported = true
 		case extensionALPN:
 			d := data[:length]
 			if len(d) < 3 {
@@ -1316,11 +1342,8 @@ func (m *certificateRequestMsg) unmarshal(data []byte) bool {
 		m.certificateAuthorities = append(m.certificateAuthorities, cas[:caLen])
 		cas = cas[caLen:]
 	}
-	if len(data) > 0 {
-		return false
-	}
 
-	return true
+	return len(data) == 0
 }
 
 type certificateVerifyMsg struct {
@@ -1466,6 +1489,17 @@ func (m *newSessionTicketMsg) unmarshal(data []byte) bool {
 	return true
 }
 
+type helloRequestMsg struct {
+}
+
+func (*helloRequestMsg) marshal() []byte {
+	return []byte{typeHelloRequest, 0, 0, 0}
+}
+
+func (*helloRequestMsg) unmarshal(data []byte) bool {
+	return len(data) == 4
+}
+
 func eqUint16s(x, y []uint16) bool {
 	if len(x) != len(y) {
 		return false
diff --git a/libgo/go/crypto/tls/handshake_server.go b/libgo/go/crypto/tls/handshake_server.go
index e16cddcbd81..1aac7295614 100644
--- a/libgo/go/crypto/tls/handshake_server.go
+++ b/libgo/go/crypto/tls/handshake_server.go
@@ -35,6 +35,7 @@ type serverHandshakeState struct {
 }
 
 // serverHandshake performs a TLS handshake as a server.
+// c.out.Mutex <= L; c.handshakeMutex <= L.
 func (c *Conn) serverHandshake() error {
 	config := c.config
 
@@ -51,6 +52,7 @@ func (c *Conn) serverHandshake() error {
 	}
 
 	// For an overview of TLS handshaking, see https://tools.ietf.org/html/rfc5246#section-7.3
+	c.buffering = true
 	if isResume {
 		// The client has included a session ticket and so we do an abbreviated handshake.
 		if err := hs.doResumeHandshake(); err != nil {
@@ -67,9 +69,13 @@ func (c *Conn) serverHandshake() error {
 				return err
 			}
 		}
-		if err := hs.sendFinished(c.firstFinished[:]); err != nil {
+		if err := hs.sendFinished(c.serverFinished[:]); err != nil {
 			return err
 		}
+		if _, err := c.flush(); err != nil {
+			return err
+		}
+		c.clientFinishedIsFirst = false
 		if err := hs.readFinished(nil); err != nil {
 			return err
 		}
@@ -83,15 +89,20 @@ func (c *Conn) serverHandshake() error {
 		if err := hs.establishKeys(); err != nil {
 			return err
 		}
-		if err := hs.readFinished(c.firstFinished[:]); err != nil {
+		if err := hs.readFinished(c.clientFinished[:]); err != nil {
 			return err
 		}
+		c.clientFinishedIsFirst = true
+		c.buffering = true
 		if err := hs.sendSessionTicket(); err != nil {
 			return err
 		}
 		if err := hs.sendFinished(nil); err != nil {
 			return err
 		}
+		if _, err := c.flush(); err != nil {
+			return err
+		}
 	}
 	c.handshakeComplete = true
 
@@ -165,7 +176,13 @@ Curves:
 		c.sendAlert(alertInternalError)
 		return false, err
 	}
-	hs.hello.secureRenegotiation = hs.clientHello.secureRenegotiation
+
+	if len(hs.clientHello.secureRenegotiation) != 0 {
+		c.sendAlert(alertHandshakeFailure)
+		return false, errors.New("tls: initial handshake had non-empty renegotiation extension")
+	}
+
+	hs.hello.secureRenegotiationSupported = hs.clientHello.secureRenegotiationSupported
 	hs.hello.compressionMethod = compressionNone
 	if len(hs.clientHello.serverName) > 0 {
 		c.serverName = hs.clientHello.serverName
@@ -187,12 +204,13 @@ Curves:
 		}
 	}
 
-	if hs.cert, err = config.getCertificate(&ClientHelloInfo{
+	hs.cert, err = config.getCertificate(&ClientHelloInfo{
 		CipherSuites:    hs.clientHello.cipherSuites,
 		ServerName:      hs.clientHello.serverName,
 		SupportedCurves: hs.clientHello.supportedCurves,
 		SupportedPoints: hs.clientHello.supportedPoints,
-	}); err != nil {
+	})
+	if err != nil {
 		c.sendAlert(alertInternalError)
 		return false, err
 	}
@@ -208,7 +226,7 @@ Curves:
 			hs.rsaSignOk = true
 		default:
 			c.sendAlert(alertInternalError)
-			return false, fmt.Errorf("crypto/tls: unsupported signing key type (%T)", priv.Public())
+			return false, fmt.Errorf("tls: unsupported signing key type (%T)", priv.Public())
 		}
 	}
 	if priv, ok := hs.cert.PrivateKey.(crypto.Decrypter); ok {
@@ -217,7 +235,7 @@ Curves:
 			hs.rsaDecryptOk = true
 		default:
 			c.sendAlert(alertInternalError)
-			return false, fmt.Errorf("crypto/tls: unsupported decryption key type (%T)", priv.Public())
+			return false, fmt.Errorf("tls: unsupported decryption key type (%T)", priv.Public())
 		}
 	}
 
@@ -245,7 +263,7 @@ Curves:
 		return false, errors.New("tls: no cipher suite supported by both client and server")
 	}
 
-	// See https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00.
+	// See https://tools.ietf.org/html/rfc7507.
 	for _, id := range hs.clientHello.cipherSuites {
 		if id == TLS_FALLBACK_SCSV {
 			// The client is doing a fallback connection.
@@ -274,10 +292,8 @@ func (hs *serverHandshakeState) checkForResumption() bool {
 		return false
 	}
 
-	if hs.sessionState.vers > hs.clientHello.vers {
-		return false
-	}
-	if vers, ok := c.config.mutualVersion(hs.sessionState.vers); !ok || vers != hs.sessionState.vers {
+	// Never resume a session for a different TLS version.
+	if c.vers != hs.sessionState.vers {
 		return false
 	}
 
@@ -322,7 +338,9 @@ func (hs *serverHandshakeState) doResumeHandshake() error {
 	hs.finishedHash.discardHandshakeBuffer()
 	hs.finishedHash.Write(hs.clientHello.marshal())
 	hs.finishedHash.Write(hs.hello.marshal())
-	c.writeRecord(recordTypeHandshake, hs.hello.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, hs.hello.marshal()); err != nil {
+		return err
+	}
 
 	if len(hs.sessionState.certificates) > 0 {
 		if _, err := hs.processCertsFromClient(hs.sessionState.certificates); err != nil {
@@ -354,19 +372,25 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 	}
 	hs.finishedHash.Write(hs.clientHello.marshal())
 	hs.finishedHash.Write(hs.hello.marshal())
-	c.writeRecord(recordTypeHandshake, hs.hello.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, hs.hello.marshal()); err != nil {
+		return err
+	}
 
 	certMsg := new(certificateMsg)
 	certMsg.certificates = hs.cert.Certificate
 	hs.finishedHash.Write(certMsg.marshal())
-	c.writeRecord(recordTypeHandshake, certMsg.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil {
+		return err
+	}
 
 	if hs.hello.ocspStapling {
 		certStatus := new(certificateStatusMsg)
 		certStatus.statusType = statusTypeOCSP
 		certStatus.response = hs.cert.OCSPStaple
 		hs.finishedHash.Write(certStatus.marshal())
-		c.writeRecord(recordTypeHandshake, certStatus.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, certStatus.marshal()); err != nil {
+			return err
+		}
 	}
 
 	keyAgreement := hs.suite.ka(c.vers)
@@ -377,7 +401,9 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 	}
 	if skx != nil {
 		hs.finishedHash.Write(skx.marshal())
-		c.writeRecord(recordTypeHandshake, skx.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, skx.marshal()); err != nil {
+			return err
+		}
 	}
 
 	if config.ClientAuth >= RequestClientCert {
@@ -401,12 +427,20 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 			certReq.certificateAuthorities = config.ClientCAs.Subjects()
 		}
 		hs.finishedHash.Write(certReq.marshal())
-		c.writeRecord(recordTypeHandshake, certReq.marshal())
+		if _, err := c.writeRecord(recordTypeHandshake, certReq.marshal()); err != nil {
+			return err
+		}
 	}
 
 	helloDone := new(serverHelloDoneMsg)
 	hs.finishedHash.Write(helloDone.marshal())
-	c.writeRecord(recordTypeHandshake, helloDone.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, helloDone.marshal()); err != nil {
+		return err
+	}
+
+	if _, err := c.flush(); err != nil {
+		return err
+	}
 
 	var pub crypto.PublicKey // public key for client auth, if any
 
@@ -462,7 +496,7 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 
 	// If we received a client cert in response to our certificate request message,
 	// the client will send us a certificateVerifyMsg immediately after the
-	// clientKeyExchangeMsg.  This message is a digest of all preceding
+	// clientKeyExchangeMsg. This message is a digest of all preceding
 	// handshake-layer messages that is signed using the private key corresponding
 	// to the client's certificate. This allows us to verify that the client is in
 	// possession of the private key of the certificate.
@@ -499,7 +533,7 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 		switch key := pub.(type) {
 		case *ecdsa.PublicKey:
 			if signatureAndHash.signature != signatureECDSA {
-				err = errors.New("bad signature type for client's ECDSA certificate")
+				err = errors.New("tls: bad signature type for client's ECDSA certificate")
 				break
 			}
 			ecdsaSig := new(ecdsaSignature)
@@ -507,7 +541,7 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 				break
 			}
 			if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
-				err = errors.New("ECDSA signature contained zero or negative values")
+				err = errors.New("tls: ECDSA signature contained zero or negative values")
 				break
 			}
 			var digest []byte
@@ -515,11 +549,11 @@ func (hs *serverHandshakeState) doFullHandshake() error {
 				break
 			}
 			if !ecdsa.Verify(key, digest, ecdsaSig.R, ecdsaSig.S) {
-				err = errors.New("ECDSA verification failure")
+				err = errors.New("tls: ECDSA verification failure")
 			}
 		case *rsa.PublicKey:
 			if signatureAndHash.signature != signatureRSA {
-				err = errors.New("bad signature type for client's RSA certificate")
+				err = errors.New("tls: bad signature type for client's RSA certificate")
 				break
 			}
 			var digest []byte
@@ -571,8 +605,8 @@ func (hs *serverHandshakeState) readFinished(out []byte) error {
 	c := hs.c
 
 	c.readRecord(recordTypeChangeCipherSpec)
-	if err := c.in.error(); err != nil {
-		return err
+	if c.in.err != nil {
+		return c.in.err
 	}
 
 	if hs.hello.nextProtoNeg {
@@ -632,7 +666,9 @@ func (hs *serverHandshakeState) sendSessionTicket() error {
 	}
 
 	hs.finishedHash.Write(m.marshal())
-	c.writeRecord(recordTypeHandshake, m.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, m.marshal()); err != nil {
+		return err
+	}
 
 	return nil
 }
@@ -640,12 +676,16 @@ func (hs *serverHandshakeState) sendSessionTicket() error {
 func (hs *serverHandshakeState) sendFinished(out []byte) error {
 	c := hs.c
 
-	c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
+	if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil {
+		return err
+	}
 
 	finished := new(finishedMsg)
 	finished.verifyData = hs.finishedHash.serverSum(hs.masterSecret)
 	hs.finishedHash.Write(finished.marshal())
-	c.writeRecord(recordTypeHandshake, finished.marshal())
+	if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil {
+		return err
+	}
 
 	c.cipherSuite = hs.suite.id
 	copy(out, finished.verifyData)
@@ -690,20 +730,20 @@ func (hs *serverHandshakeState) processCertsFromClient(certificates [][]byte) (c
 		c.verifiedChains = chains
 	}
 
-	if len(certs) > 0 {
-		var pub crypto.PublicKey
-		switch key := certs[0].PublicKey.(type) {
-		case *ecdsa.PublicKey, *rsa.PublicKey:
-			pub = key
-		default:
-			c.sendAlert(alertUnsupportedCertificate)
-			return nil, fmt.Errorf("tls: client's certificate contains an unsupported public key of type %T", certs[0].PublicKey)
-		}
-		c.peerCertificates = certs
-		return pub, nil
+	if len(certs) == 0 {
+		return nil, nil
 	}
 
-	return nil, nil
+	var pub crypto.PublicKey
+	switch key := certs[0].PublicKey.(type) {
+	case *ecdsa.PublicKey, *rsa.PublicKey:
+		pub = key
+	default:
+		c.sendAlert(alertUnsupportedCertificate)
+		return nil, fmt.Errorf("tls: client's certificate contains an unsupported public key of type %T", certs[0].PublicKey)
+	}
+	c.peerCertificates = certs
+	return pub, nil
 }
 
 // setCipherSuite sets a cipherSuite with the given id as the serverHandshakeState
diff --git a/libgo/go/crypto/tls/handshake_server_test.go b/libgo/go/crypto/tls/handshake_server_test.go
index 438fb3140a3..9ae5d11fc18 100644
--- a/libgo/go/crypto/tls/handshake_server_test.go
+++ b/libgo/go/crypto/tls/handshake_server_test.go
@@ -69,7 +69,7 @@ func testClientHello(t *testing.T, serverConfig *Config, m handshakeMessage) {
 
 func testClientHelloFailure(t *testing.T, serverConfig *Config, m handshakeMessage, expectedSubStr string) {
 	// Create in-memory network connection,
-	// send message to server.  Should return
+	// send message to server. Should return
 	// expected error.
 	c, s := net.Pipe()
 	go func() {
@@ -80,7 +80,10 @@ func testClientHelloFailure(t *testing.T, serverConfig *Config, m handshakeMessa
 		cli.writeRecord(recordTypeHandshake, m.marshal())
 		c.Close()
 	}()
-	err := Server(s, serverConfig).Handshake()
+	hs := serverHandshakeState{
+		c: Server(s, serverConfig),
+	}
+	_, err := hs.readClientHello()
 	s.Close()
 	if len(expectedSubStr) == 0 {
 		if err != nil && err != io.EOF {
@@ -105,16 +108,16 @@ func TestRejectBadProtocolVersion(t *testing.T) {
 
 func TestNoSuiteOverlap(t *testing.T) {
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{0xff00},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 	}
 	testClientHelloFailure(t, testConfig, clientHello, "no cipher suite supported by both client and server")
 }
 
 func TestNoCompressionOverlap(t *testing.T) {
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_RSA_WITH_RC4_128_SHA},
 		compressionMethods: []uint8{0xff},
 	}
@@ -123,56 +126,56 @@ func TestNoCompressionOverlap(t *testing.T) {
 
 func TestNoRC4ByDefault(t *testing.T) {
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_RSA_WITH_RC4_128_SHA},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 	}
-	serverConfig := *testConfig
+	serverConfig := testConfig.clone()
 	// Reset the enabled cipher suites to nil in order to test the
 	// defaults.
 	serverConfig.CipherSuites = nil
-	testClientHelloFailure(t, &serverConfig, clientHello, "no cipher suite supported by both client and server")
+	testClientHelloFailure(t, serverConfig, clientHello, "no cipher suite supported by both client and server")
 }
 
 func TestDontSelectECDSAWithRSAKey(t *testing.T) {
 	// Test that, even when both sides support an ECDSA cipher suite, it
 	// won't be selected if the server's private key doesn't support it.
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 		supportedCurves:    []CurveID{CurveP256},
 		supportedPoints:    []uint8{pointFormatUncompressed},
 	}
-	serverConfig := *testConfig
+	serverConfig := testConfig.clone()
 	serverConfig.CipherSuites = clientHello.cipherSuites
 	serverConfig.Certificates = make([]Certificate, 1)
 	serverConfig.Certificates[0].Certificate = [][]byte{testECDSACertificate}
 	serverConfig.Certificates[0].PrivateKey = testECDSAPrivateKey
 	serverConfig.BuildNameToCertificate()
 	// First test that it *does* work when the server's key is ECDSA.
-	testClientHello(t, &serverConfig, clientHello)
+	testClientHello(t, serverConfig, clientHello)
 
 	// Now test that switching to an RSA key causes the expected error (and
 	// not an internal error about a signing failure).
 	serverConfig.Certificates = testConfig.Certificates
-	testClientHelloFailure(t, &serverConfig, clientHello, "no cipher suite supported by both client and server")
+	testClientHelloFailure(t, serverConfig, clientHello, "no cipher suite supported by both client and server")
 }
 
 func TestDontSelectRSAWithECDSAKey(t *testing.T) {
 	// Test that, even when both sides support an RSA cipher suite, it
 	// won't be selected if the server's private key doesn't support it.
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 		supportedCurves:    []CurveID{CurveP256},
 		supportedPoints:    []uint8{pointFormatUncompressed},
 	}
-	serverConfig := *testConfig
+	serverConfig := testConfig.clone()
 	serverConfig.CipherSuites = clientHello.cipherSuites
 	// First test that it *does* work when the server's key is RSA.
-	testClientHello(t, &serverConfig, clientHello)
+	testClientHello(t, serverConfig, clientHello)
 
 	// Now test that switching to an ECDSA key causes the expected error
 	// (and not an internal error about a signing failure).
@@ -180,16 +183,16 @@ func TestDontSelectRSAWithECDSAKey(t *testing.T) {
 	serverConfig.Certificates[0].Certificate = [][]byte{testECDSACertificate}
 	serverConfig.Certificates[0].PrivateKey = testECDSAPrivateKey
 	serverConfig.BuildNameToCertificate()
-	testClientHelloFailure(t, &serverConfig, clientHello, "no cipher suite supported by both client and server")
+	testClientHelloFailure(t, serverConfig, clientHello, "no cipher suite supported by both client and server")
 }
 
 func TestRenegotiationExtension(t *testing.T) {
 	clientHello := &clientHelloMsg{
-		vers:                VersionTLS12,
-		compressionMethods:  []uint8{compressionNone},
-		random:              make([]byte, 32),
-		secureRenegotiation: true,
-		cipherSuites:        []uint16{TLS_RSA_WITH_RC4_128_SHA},
+		vers:               VersionTLS12,
+		compressionMethods: []uint8{compressionNone},
+		random:             make([]byte, 32),
+		secureRenegotiationSupported: true,
+		cipherSuites:                 []uint16{TLS_RSA_WITH_RC4_128_SHA},
 	}
 
 	var buf []byte
@@ -226,7 +229,7 @@ func TestRenegotiationExtension(t *testing.T) {
 		t.Fatalf("Failed to parse ServerHello")
 	}
 
-	if !serverHello.secureRenegotiation {
+	if !serverHello.secureRenegotiationSupported {
 		t.Errorf("Secure renegotiation extension was not echoed.")
 	}
 }
@@ -262,9 +265,9 @@ func TestTLS12OnlyCipherSuites(t *testing.T) {
 		reply, clientErr = cli.readHandshake()
 		c.Close()
 	}()
-	config := *testConfig
+	config := testConfig.clone()
 	config.CipherSuites = clientHello.cipherSuites
-	Server(s, &config).Handshake()
+	Server(s, config).Handshake()
 	s.Close()
 	if clientErr != nil {
 		t.Fatal(clientErr)
@@ -396,6 +399,64 @@ func TestSCTHandshake(t *testing.T) {
 	}
 }
 
+func TestCrossVersionResume(t *testing.T) {
+	serverConfig := &Config{
+		CipherSuites: []uint16{TLS_RSA_WITH_AES_128_CBC_SHA},
+		Certificates: testConfig.Certificates,
+	}
+	clientConfig := &Config{
+		CipherSuites:       []uint16{TLS_RSA_WITH_AES_128_CBC_SHA},
+		InsecureSkipVerify: true,
+		ClientSessionCache: NewLRUClientSessionCache(1),
+		ServerName:         "servername",
+	}
+
+	// Establish a session at TLS 1.1.
+	clientConfig.MaxVersion = VersionTLS11
+	_, _, err := testHandshake(clientConfig, serverConfig)
+	if err != nil {
+		t.Fatalf("handshake failed: %s", err)
+	}
+
+	// The client session cache now contains a TLS 1.1 session.
+	state, _, err := testHandshake(clientConfig, serverConfig)
+	if err != nil {
+		t.Fatalf("handshake failed: %s", err)
+	}
+	if !state.DidResume {
+		t.Fatalf("handshake did not resume at the same version")
+	}
+
+	// Test that the server will decline to resume at a lower version.
+	clientConfig.MaxVersion = VersionTLS10
+	state, _, err = testHandshake(clientConfig, serverConfig)
+	if err != nil {
+		t.Fatalf("handshake failed: %s", err)
+	}
+	if state.DidResume {
+		t.Fatalf("handshake resumed at a lower version")
+	}
+
+	// The client session cache now contains a TLS 1.0 session.
+	state, _, err = testHandshake(clientConfig, serverConfig)
+	if err != nil {
+		t.Fatalf("handshake failed: %s", err)
+	}
+	if !state.DidResume {
+		t.Fatalf("handshake did not resume at the same version")
+	}
+
+	// Test that the server will decline to resume at a higher version.
+	clientConfig.MaxVersion = VersionTLS11
+	state, _, err = testHandshake(clientConfig, serverConfig)
+	if err != nil {
+		t.Fatalf("handshake failed: %s", err)
+	}
+	if state.DidResume {
+		t.Fatalf("handshake resumed at a higher version")
+	}
+}
+
 // Note: see comment in handshake_test.go for details of how the reference
 // tests work.
 
@@ -518,16 +579,17 @@ func (test *serverTest) run(t *testing.T, write bool) {
 	server := Server(serverConn, config)
 	connStateChan := make(chan ConnectionState, 1)
 	go func() {
-		var err error
-		if _, err = server.Write([]byte("hello, world\n")); err != nil {
-			t.Logf("Error from Server.Write: %s", err)
-		}
+		_, err := server.Write([]byte("hello, world\n"))
 		if len(test.expectHandshakeErrorIncluding) > 0 {
 			if err == nil {
 				t.Errorf("Error expected, but no error returned")
 			} else if s := err.Error(); !strings.Contains(s, test.expectHandshakeErrorIncluding) {
 				t.Errorf("Error expected containing '%s' but got '%s'", test.expectHandshakeErrorIncluding, s)
 			}
+		} else {
+			if err != nil {
+				t.Logf("Error from Server.Write: '%s'", err)
+			}
 		}
 		server.Close()
 		serverConn.Close()
@@ -670,7 +732,7 @@ func TestHandshakeServerAES256GCMSHA384(t *testing.T) {
 }
 
 func TestHandshakeServerECDHEECDSAAES(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	config.Certificates = make([]Certificate, 1)
 	config.Certificates[0].Certificate = [][]byte{testECDSACertificate}
 	config.Certificates[0].PrivateKey = testECDSAPrivateKey
@@ -679,14 +741,14 @@ func TestHandshakeServerECDHEECDSAAES(t *testing.T) {
 	test := &serverTest{
 		name:    "ECDHE-ECDSA-AES",
 		command: []string{"openssl", "s_client", "-no_ticket", "-cipher", "ECDHE-ECDSA-AES256-SHA"},
-		config:  &config,
+		config:  config,
 	}
 	runServerTestTLS10(t, test)
 	runServerTestTLS12(t, test)
 }
 
 func TestHandshakeServerALPN(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	config.NextProtos = []string{"proto1", "proto2"}
 
 	test := &serverTest{
@@ -694,7 +756,7 @@ func TestHandshakeServerALPN(t *testing.T) {
 		// Note that this needs OpenSSL 1.0.2 because that is the first
 		// version that supports the -alpn flag.
 		command: []string{"openssl", "s_client", "-alpn", "proto2,proto1"},
-		config:  &config,
+		config:  config,
 		validate: func(state ConnectionState) error {
 			// The server's preferences should override the client.
 			if state.NegotiatedProtocol != "proto1" {
@@ -707,7 +769,7 @@ func TestHandshakeServerALPN(t *testing.T) {
 }
 
 func TestHandshakeServerALPNNoMatch(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	config.NextProtos = []string{"proto3"}
 
 	test := &serverTest{
@@ -715,7 +777,7 @@ func TestHandshakeServerALPNNoMatch(t *testing.T) {
 		// Note that this needs OpenSSL 1.0.2 because that is the first
 		// version that supports the -alpn flag.
 		command: []string{"openssl", "s_client", "-alpn", "proto2,proto1"},
-		config:  &config,
+		config:  config,
 		validate: func(state ConnectionState) error {
 			// Rather than reject the connection, Go doesn't select
 			// a protocol when there is no overlap.
@@ -742,7 +804,7 @@ func TestHandshakeServerSNI(t *testing.T) {
 // TestHandshakeServerSNICertForName is similar to TestHandshakeServerSNI, but
 // tests the dynamic GetCertificate method
 func TestHandshakeServerSNIGetCertificate(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 
 	// Replace the NameToCertificate map with a GetCertificate function
 	nameToCert := config.NameToCertificate
@@ -754,7 +816,7 @@ func TestHandshakeServerSNIGetCertificate(t *testing.T) {
 	test := &serverTest{
 		name:    "SNI-GetCertificate",
 		command: []string{"openssl", "s_client", "-no_ticket", "-cipher", "AES128-SHA", "-servername", "snitest.com"},
-		config:  &config,
+		config:  config,
 	}
 	runServerTestTLS12(t, test)
 }
@@ -764,7 +826,7 @@ func TestHandshakeServerSNIGetCertificate(t *testing.T) {
 // GetCertificate method doesn't return a cert, we fall back to what's in
 // the NameToCertificate map.
 func TestHandshakeServerSNIGetCertificateNotFound(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 
 	config.GetCertificate = func(clientHello *ClientHelloInfo) (*Certificate, error) {
 		return nil, nil
@@ -772,7 +834,7 @@ func TestHandshakeServerSNIGetCertificateNotFound(t *testing.T) {
 	test := &serverTest{
 		name:    "SNI-GetCertificateNotFound",
 		command: []string{"openssl", "s_client", "-no_ticket", "-cipher", "AES128-SHA", "-servername", "snitest.com"},
-		config:  &config,
+		config:  config,
 	}
 	runServerTestTLS12(t, test)
 }
@@ -782,18 +844,18 @@ func TestHandshakeServerSNIGetCertificateNotFound(t *testing.T) {
 func TestHandshakeServerSNIGetCertificateError(t *testing.T) {
 	const errMsg = "TestHandshakeServerSNIGetCertificateError error"
 
-	serverConfig := *testConfig
+	serverConfig := testConfig.clone()
 	serverConfig.GetCertificate = func(clientHello *ClientHelloInfo) (*Certificate, error) {
 		return nil, errors.New(errMsg)
 	}
 
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_RSA_WITH_RC4_128_SHA},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 		serverName:         "test",
 	}
-	testClientHelloFailure(t, &serverConfig, clientHello, errMsg)
+	testClientHelloFailure(t, serverConfig, clientHello, errMsg)
 }
 
 // TestHandshakeServerEmptyCertificates tests that GetCertificates is called in
@@ -801,45 +863,45 @@ func TestHandshakeServerSNIGetCertificateError(t *testing.T) {
 func TestHandshakeServerEmptyCertificates(t *testing.T) {
 	const errMsg = "TestHandshakeServerEmptyCertificates error"
 
-	serverConfig := *testConfig
+	serverConfig := testConfig.clone()
 	serverConfig.GetCertificate = func(clientHello *ClientHelloInfo) (*Certificate, error) {
 		return nil, errors.New(errMsg)
 	}
 	serverConfig.Certificates = nil
 
 	clientHello := &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_RSA_WITH_RC4_128_SHA},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 	}
-	testClientHelloFailure(t, &serverConfig, clientHello, errMsg)
+	testClientHelloFailure(t, serverConfig, clientHello, errMsg)
 
 	// With an empty Certificates and a nil GetCertificate, the server
 	// should always return a “no certificates” error.
 	serverConfig.GetCertificate = nil
 
 	clientHello = &clientHelloMsg{
-		vers:               0x0301,
+		vers:               VersionTLS10,
 		cipherSuites:       []uint16{TLS_RSA_WITH_RC4_128_SHA},
-		compressionMethods: []uint8{0},
+		compressionMethods: []uint8{compressionNone},
 	}
-	testClientHelloFailure(t, &serverConfig, clientHello, "no certificates")
+	testClientHelloFailure(t, serverConfig, clientHello, "no certificates")
 }
 
 // TestCipherSuiteCertPreferance ensures that we select an RSA ciphersuite with
 // an RSA certificate and an ECDSA ciphersuite with an ECDSA certificate.
 func TestCipherSuiteCertPreferenceECDSA(t *testing.T) {
-	config := *testConfig
+	config := testConfig.clone()
 	config.CipherSuites = []uint16{TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA}
 	config.PreferServerCipherSuites = true
 
 	test := &serverTest{
 		name:   "CipherSuiteCertPreferenceRSA",
-		config: &config,
+		config: config,
 	}
 	runServerTestTLS12(t, test)
 
-	config = *testConfig
+	config = testConfig.clone()
 	config.CipherSuites = []uint16{TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA}
 	config.Certificates = []Certificate{
 		{
@@ -852,7 +914,7 @@ func TestCipherSuiteCertPreferenceECDSA(t *testing.T) {
 
 	test = &serverTest{
 		name:   "CipherSuiteCertPreferenceECDSA",
-		config: &config,
+		config: config,
 	}
 	runServerTestTLS12(t, test)
 }
@@ -878,12 +940,12 @@ func TestResumptionDisabled(t *testing.T) {
 	sessionFilePath := tempFile("")
 	defer os.Remove(sessionFilePath)
 
-	config := *testConfig
+	config := testConfig.clone()
 
 	test := &serverTest{
 		name:    "IssueTicketPreDisable",
 		command: []string{"openssl", "s_client", "-cipher", "RC4-SHA", "-sess_out", sessionFilePath},
-		config:  &config,
+		config:  config,
 	}
 	runServerTestTLS12(t, test)
 
@@ -892,7 +954,7 @@ func TestResumptionDisabled(t *testing.T) {
 	test = &serverTest{
 		name:    "ResumeDisabled",
 		command: []string{"openssl", "s_client", "-cipher", "RC4-SHA", "-sess_in", sessionFilePath},
-		config:  &config,
+		config:  config,
 	}
 	runServerTestTLS12(t, test)
 
@@ -901,12 +963,12 @@ func TestResumptionDisabled(t *testing.T) {
 }
 
 func TestFallbackSCSV(t *testing.T) {
-	serverConfig := &Config{
+	serverConfig := Config{
 		Certificates: testConfig.Certificates,
 	}
 	test := &serverTest{
 		name:   "FallbackSCSV",
-		config: serverConfig,
+		config: &serverConfig,
 		// OpenSSL 1.0.1j is needed for the -fallback_scsv option.
 		command: []string{"openssl", "s_client", "-fallback_scsv"},
 		expectHandshakeErrorIncluding: "inappropriate protocol fallback",
@@ -991,20 +1053,20 @@ func TestClientAuth(t *testing.T) {
 		defer os.Remove(ecdsaKeyPath)
 	}
 
-	config := *testConfig
+	config := testConfig.clone()
 	config.ClientAuth = RequestClientCert
 
 	test := &serverTest{
 		name:    "ClientAuthRequestedNotGiven",
 		command: []string{"openssl", "s_client", "-no_ticket", "-cipher", "RC4-SHA"},
-		config:  &config,
+		config:  config,
 	}
 	runServerTestTLS12(t, test)
 
 	test = &serverTest{
 		name:              "ClientAuthRequestedAndGiven",
 		command:           []string{"openssl", "s_client", "-no_ticket", "-cipher", "RC4-SHA", "-cert", certPath, "-key", keyPath},
-		config:            &config,
+		config:            config,
 		expectedPeerCerts: []string{clientCertificatePEM},
 	}
 	runServerTestTLS12(t, test)
@@ -1012,7 +1074,7 @@ func TestClientAuth(t *testing.T) {
 	test = &serverTest{
 		name:              "ClientAuthRequestedAndECDSAGiven",
 		command:           []string{"openssl", "s_client", "-no_ticket", "-cipher", "RC4-SHA", "-cert", ecdsaCertPath, "-key", ecdsaKeyPath},
-		config:            &config,
+		config:            config,
 		expectedPeerCerts: []string{clientECDSACertificatePEM},
 	}
 	runServerTestTLS12(t, test)
diff --git a/libgo/go/crypto/tls/key_agreement.go b/libgo/go/crypto/tls/key_agreement.go
index 0e6a7c22624..467efb2bf5c 100644
--- a/libgo/go/crypto/tls/key_agreement.go
+++ b/libgo/go/crypto/tls/key_agreement.go
@@ -51,7 +51,7 @@ func (ka rsaKeyAgreement) processClientKeyExchange(config *Config, cert *Certifi
 	if err != nil {
 		return nil, err
 	}
-	// We don't check the version number in the premaster secret.  For one,
+	// We don't check the version number in the premaster secret. For one,
 	// by checking it, we would leak information about the validity of the
 	// encrypted pre-master secret. Secondly, it provides only a small
 	// benefit against a downgrade attack and some implementations send the
@@ -242,19 +242,19 @@ NextCandidate:
 	case signatureECDSA:
 		_, ok := priv.Public().(*ecdsa.PublicKey)
 		if !ok {
-			return nil, errors.New("ECDHE ECDSA requires an ECDSA server key")
+			return nil, errors.New("tls: ECDHE ECDSA requires an ECDSA server key")
 		}
 	case signatureRSA:
 		_, ok := priv.Public().(*rsa.PublicKey)
 		if !ok {
-			return nil, errors.New("ECDHE RSA requires a RSA server key")
+			return nil, errors.New("tls: ECDHE RSA requires a RSA server key")
 		}
 	default:
-		return nil, errors.New("unknown ECDHE signature algorithm")
+		return nil, errors.New("tls: unknown ECDHE signature algorithm")
 	}
 	sig, err = priv.Sign(config.rand(), digest, hashFunc)
 	if err != nil {
-		return nil, errors.New("failed to sign ECDHE parameters: " + err.Error())
+		return nil, errors.New("tls: failed to sign ECDHE parameters: " + err.Error())
 	}
 
 	skx := new(serverKeyExchangeMsg)
@@ -354,28 +354,28 @@ func (ka *ecdheKeyAgreement) processServerKeyExchange(config *Config, clientHell
 	case signatureECDSA:
 		pubKey, ok := cert.PublicKey.(*ecdsa.PublicKey)
 		if !ok {
-			return errors.New("ECDHE ECDSA requires a ECDSA server public key")
+			return errors.New("tls: ECDHE ECDSA requires a ECDSA server public key")
 		}
 		ecdsaSig := new(ecdsaSignature)
 		if _, err := asn1.Unmarshal(sig, ecdsaSig); err != nil {
 			return err
 		}
 		if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
-			return errors.New("ECDSA signature contained zero or negative values")
+			return errors.New("tls: ECDSA signature contained zero or negative values")
 		}
 		if !ecdsa.Verify(pubKey, digest, ecdsaSig.R, ecdsaSig.S) {
-			return errors.New("ECDSA verification failure")
+			return errors.New("tls: ECDSA verification failure")
 		}
 	case signatureRSA:
 		pubKey, ok := cert.PublicKey.(*rsa.PublicKey)
 		if !ok {
-			return errors.New("ECDHE RSA requires a RSA server public key")
+			return errors.New("tls: ECDHE RSA requires a RSA server public key")
 		}
 		if err := rsa.VerifyPKCS1v15(pubKey, hashFunc, digest, sig); err != nil {
 			return err
 		}
 	default:
-		return errors.New("unknown ECDHE signature algorithm")
+		return errors.New("tls: unknown ECDHE signature algorithm")
 	}
 
 	return nil
@@ -383,7 +383,7 @@ func (ka *ecdheKeyAgreement) processServerKeyExchange(config *Config, clientHell
 
 func (ka *ecdheKeyAgreement) generateClientKeyExchange(config *Config, clientHello *clientHelloMsg, cert *x509.Certificate) ([]byte, *clientKeyExchangeMsg, error) {
 	if ka.curve == nil {
-		return nil, nil, errors.New("missing ServerKeyExchange message")
+		return nil, nil, errors.New("tls: missing ServerKeyExchange message")
 	}
 	priv, mx, my, err := elliptic.GenerateKey(ka.curve, config.rand())
 	if err != nil {
diff --git a/libgo/go/crypto/tls/prf.go b/libgo/go/crypto/tls/prf.go
index 747b817ba32..5833fc19631 100644
--- a/libgo/go/crypto/tls/prf.go
+++ b/libgo/go/crypto/tls/prf.go
@@ -85,7 +85,7 @@ func prf30(result, secret, label, seed []byte) {
 
 	done := 0
 	i := 0
-	// RFC5246 section 6.3 says that the largest PRF output needed is 128
+	// RFC 5246 section 6.3 says that the largest PRF output needed is 128
 	// bytes. Since no more ciphersuites will be added to SSLv3, this will
 	// remain true. Each iteration gives us 16 bytes so 10 iterations will
 	// be sufficient.
diff --git a/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateOnce b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateOnce
new file mode 100644
index 00000000000..00d35f42905
--- /dev/null
+++ b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateOnce
@@ -0,0 +1,251 @@
+>>> Flow 1 (client to server)
+00000000  16 03 01 00 85 01 00 00  81 03 03 00 00 00 00 00  |................|
+00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 22 c0 2f  |............."./|
+00000030  c0 2b c0 30 c0 2c c0 11  c0 07 c0 13 c0 09 c0 14  |.+.0.,..........|
+00000040  c0 0a 00 9c 00 9d 00 05  00 2f 00 35 c0 12 00 0a  |........./.5....|
+00000050  01 00 00 36 00 05 00 05  01 00 00 00 00 00 0a 00  |...6............|
+00000060  08 00 06 00 17 00 18 00  19 00 0b 00 02 01 00 00  |................|
+00000070  0d 00 0e 00 0c 04 01 04  03 05 01 05 03 02 01 02  |................|
+00000080  03 ff 01 00 01 00 00 12  00 00                    |..........|
+>>> Flow 2 (server to client)
+00000000  16 03 03 00 59 02 00 00  55 03 03 fa 71 0e 3c 35  |....Y...U...q.<5|
+00000010  33 cc 51 25 19 cf fe c4  ef c8 2d ec 88 75 a9 1c  |3.Q%......-..u..|
+00000020  6a e4 f3 b4 3d fd 74 cc  e1 71 71 20 de 14 e5 21  |j...=.t..qq ...!|
+00000030  84 17 62 62 4f 44 e7 c2  d6 00 07 d2 63 f8 b0 32  |..bbOD......c..2|
+00000040  e0 12 d3 cb 69 1f d8 ed  5d 43 89 86 c0 2f 00 00  |....i...]C.../..|
+00000050  0d ff 01 00 01 00 00 0b  00 04 03 00 01 02 16 03  |................|
+00000060  03 02 71 0b 00 02 6d 00  02 6a 00 02 67 30 82 02  |..q...m..j..g0..|
+00000070  63 30 82 01 cc a0 03 02  01 02 02 09 00 a2 73 00  |c0............s.|
+00000080  0c 81 00 cb f3 30 0d 06  09 2a 86 48 86 f7 0d 01  |.....0...*.H....|
+00000090  01 0b 05 00 30 2b 31 17  30 15 06 03 55 04 0a 13  |....0+1.0...U...|
+000000a0  0e 47 6f 6f 67 6c 65 20  54 45 53 54 49 4e 47 31  |.Google TESTING1|
+000000b0  10 30 0e 06 03 55 04 03  13 07 47 6f 20 52 6f 6f  |.0...U....Go Roo|
+000000c0  74 30 1e 17 0d 31 35 30  31 30 31 30 30 30 30 30  |t0...15010100000|
+000000d0  30 5a 17 0d 32 35 30 31  30 31 30 30 30 30 30 30  |0Z..250101000000|
+000000e0  5a 30 26 31 17 30 15 06  03 55 04 0a 13 0e 47 6f  |Z0&1.0...U....Go|
+000000f0  6f 67 6c 65 20 54 45 53  54 49 4e 47 31 0b 30 09  |ogle TESTING1.0.|
+00000100  06 03 55 04 03 13 02 47  6f 30 81 9f 30 0d 06 09  |..U....Go0..0...|
+00000110  2a 86 48 86 f7 0d 01 01  01 05 00 03 81 8d 00 30  |*.H............0|
+00000120  81 89 02 81 81 00 af 87  88 f6 20 1b 95 65 6c 14  |.......... ..el.|
+00000130  ab 44 05 af 3b 45 14 e3  b7 6d fd 00 63 4d 95 7f  |.D..;E...m..cM..|
+00000140  fe 6a 62 35 86 c0 4a f9  18 7c f6 aa 25 5e 7a 64  |.jb5..J..|..%^zd|
+00000150  31 66 00 ba f4 8e 92 af  c7 6b d8 76 d4 f3 5f 41  |1f.......k.v.._A|
+00000160  cb 6e 56 15 97 1b 97 c1  3c 12 39 21 66 3d 2b 16  |.nV.....<.9!f=+.|
+00000170  d1 bc db 1c c0 a7 da b7  ca ad ba da cb d5 21 50  |..............!P|
+00000180  ec de 8d ab d1 6b 81 4b  89 02 f3 c4 be c1 6c 89  |.....k.K......l.|
+00000190  b1 44 84 bd 21 d1 04 7d  9d 16 4d f9 82 15 f6 ef  |.D..!..}..M.....|
+000001a0  fa d6 09 47 f2 fb 02 03  01 00 01 a3 81 93 30 81  |...G..........0.|
+000001b0  90 30 0e 06 03 55 1d 0f  01 01 ff 04 04 03 02 05  |.0...U..........|
+000001c0  a0 30 1d 06 03 55 1d 25  04 16 30 14 06 08 2b 06  |.0...U.%..0...+.|
+000001d0  01 05 05 07 03 01 06 08  2b 06 01 05 05 07 03 02  |........+.......|
+000001e0  30 0c 06 03 55 1d 13 01  01 ff 04 02 30 00 30 19  |0...U.......0.0.|
+000001f0  06 03 55 1d 0e 04 12 04  10 12 50 8d 89 6f 1b d1  |..U.......P..o..|
+00000200  dc 54 4d 6e cb 69 5e 06  f4 30 1b 06 03 55 1d 23  |.TMn.i^..0...U.#|
+00000210  04 14 30 12 80 10 bf 3d  b6 a9 66 f2 b8 40 cf ea  |..0....=..f..@..|
+00000220  b4 03 78 48 1a 41 30 19  06 03 55 1d 11 04 12 30  |..xH.A0...U....0|
+00000230  10 82 0e 65 78 61 6d 70  6c 65 2e 67 6f 6c 61 6e  |...example.golan|
+00000240  67 30 0d 06 09 2a 86 48  86 f7 0d 01 01 0b 05 00  |g0...*.H........|
+00000250  03 81 81 00 92 7c af 91  55 12 18 96 59 31 a6 48  |.....|..U...Y1.H|
+00000260  40 d5 2d d5 ee bb 02 a0  f5 c2 1e 7c 9b b3 30 7d  |@.-........|..0}|
+00000270  3c dc 76 da 4f 3d c0 fa  ae 2d 33 24 6b 03 7b 1b  |<.v.O=...-3$k.{.|
+00000280  67 59 11 21 b5 11 bc 77  b9 d9 e0 6e a8 2d 2e 35  |gY.!...w...n.-.5|
+00000290  fa 64 5f 22 3e 63 10 6b  be ff 14 86 6d 0d f0 15  |.d_">c.k....m...|
+000002a0  31 a8 14 38 1e 3b 84 87  2c cb 98 ed 51 76 b9 b1  |1..8.;..,...Qv..|
+000002b0  4f dd db 9b 84 04 86 40  fa 51 dd ba b4 8d eb e3  |O......@.Q......|
+000002c0  46 de 46 b9 4f 86 c7 f9  a4 c2 41 34 ac cc f6 ea  |F.F.O.....A4....|
+000002d0  b0 ab 39 18 16 03 03 00  cd 0c 00 00 c9 03 00 17  |..9.............|
+000002e0  41 04 71 a0 a9 f0 31 52  0b a2 5f 44 b1 48 a6 dc  |A.q...1R.._D.H..|
+000002f0  b7 b8 bb a3 59 13 06 46  73 37 b1 9d f6 5a 42 49  |....Y..Fs7...ZBI|
+00000300  a7 e4 3c 26 64 ed 26 41  f9 76 d5 88 ad b5 2f 12  |..<&d.&A.v..../.|
+00000310  ce 02 34 b8 85 36 ee cd  a1 dc d9 d7 4b ed d2 81  |..4..6......K...|
+00000320  82 1e 04 01 00 80 86 91  0e 05 48 de 2b 45 0a 9d  |..........H.+E..|
+00000330  72 33 44 73 98 f3 0e 0f  4c 0b aa c0 6b 02 34 83  |r3Ds....L...k.4.|
+00000340  0c e1 53 04 89 47 21 22  de 09 5e d0 b3 d9 8b 53  |..S..G!"..^....S|
+00000350  62 b0 bf c6 dd fe d3 ed  d6 2e ac a0 64 9d a4 07  |b...........d...|
+00000360  1f a9 d5 89 5f 62 7f e0  b1 9b e2 ef 3e 36 89 70  |...._b......>6.p|
+00000370  3e 7c 0a e7 8c cb c3 a8  e0 91 d9 bd 6e 3d be 0e  |>|..........n=..|
+00000380  a2 8c ab 46 1b 07 24 40  da a5 e3 0b b1 6a 9f 28  |...F..$@.....j.(|
+00000390  c7 4f e8 d0 a3 57 e1 5c  f2 34 07 aa 77 28 91 a0  |.O...W.\.4..w(..|
+000003a0  7e d6 36 2c c3 1a 16 03  03 00 04 0e 00 00 00     |~.6,...........|
+>>> Flow 3 (client to server)
+00000000  16 03 03 00 46 10 00 00  42 41 04 1e 18 37 ef 0d  |....F...BA...7..|
+00000010  19 51 88 35 75 71 b5 e5  54 5b 12 2e 8f 09 67 fd  |.Q.5uq..T[....g.|
+00000020  a7 24 20 3e b2 56 1c ce  97 28 5e f8 2b 2d 4f 9e  |.$ >.V...(^.+-O.|
+00000030  f1 07 9f 6c 4b 5b 83 56  e2 32 42 e9 58 b6 d7 49  |...lK[.V.2B.X..I|
+00000040  a6 b5 68 1a 41 03 56 6b  dc 5a 89 14 03 03 00 01  |..h.A.Vk.Z......|
+00000050  01 16 03 03 00 28 00 00  00 00 00 00 00 00 53 c5  |.....(........S.|
+00000060  60 30 29 1d 8a 38 57 f3  6d d1 f4 e1 ec 3e 79 d1  |`0)..8W.m....>y.|
+00000070  79 d3 b8 7f 4e 71 41 d6  72 fa c0 cd 53 92        |y...NqA.r...S.|
+>>> Flow 4 (server to client)
+00000000  14 03 03 00 01 01 16 03  03 00 28 86 be df d2 27  |..........(....'|
+00000010  8b 37 77 eb 0b e4 6e 38  5c 27 56 48 bb b5 f2 be  |.7w...n8\'VH....|
+00000020  43 e5 f7 32 d2 d3 a1 d7  4e 6a 3c 76 17 94 c1 b0  |C..2....Nj<v....|
+00000030  06 af 67                                          |..g|
+>>> Flow 5 (client to server)
+00000000  17 03 03 00 1e 00 00 00  00 00 00 00 01 17 22 06  |..............".|
+00000010  f7 50 b5 6f 65 e0 dd f9  b6 bc 50 b7 91 c9 54 5c  |.P.oe.....P...T\|
+00000020  4e 2f cc                                          |N/.|
+>>> Flow 6 (server to client)
+00000000  16 03 03 00 1c 86 be df  d2 27 8b 37 78 c8 e7 d6  |.........'.7x...|
+00000010  4b e4 60 9e 4c b0 28 79  d9 7a 78 58 d8 27 76 18  |K.`.L.(y.zxX.'v.|
+00000020  a3                                                |.|
+>>> Flow 7 (client to server)
+00000000  16 03 03 00 a9 00 00 00  00 00 00 00 02 a7 17 56  |...............V|
+00000010  8e ea 2e fc 76 06 40 b2  fa 10 71 62 68 b9 14 e6  |....v.@...qbh...|
+00000020  09 6d 63 86 d1 6b 87 3a  c4 84 15 77 68 f8 85 ec  |.mc..k.:...wh...|
+00000030  55 49 3c c5 c1 be 24 85  0c 38 4b 66 a8 5f 33 f9  |UI<...$..8Kf._3.|
+00000040  a3 e5 d1 36 fd 25 ba 9d  54 1f 4c df 66 09 a7 08  |...6.%..T.L.f...|
+00000050  8d 7c a4 7e d4 5d c2 11  77 7b 48 7a 32 f7 88 0a  |.|.~.]..w{Hz2...|
+00000060  51 5f 6a 26 e2 11 88 01  5b b6 8e 6a aa 18 79 85  |Q_j&....[..j..y.|
+00000070  6a 0e 31 1f 33 5e 34 fd  e9 1c 84 7c ea 6c 78 5d  |j.1.3^4....|.lx]|
+00000080  0e d2 df c0 8c 92 3d 48  fc 9e 47 18 2a a7 1e e3  |......=H..G.*...|
+00000090  9b 89 6f 30 d0 fd 0a cd  4c b9 d9 89 b6 72 53 54  |..o0....L....rST|
+000000a0  3e 02 c3 d0 68 b0 4e 40  06 86 cd 8e 87 53        |>...h.N@.....S|
+>>> Flow 8 (server to client)
+00000000  16 03 03 00 89 86 be df  d2 27 8b 37 79 29 01 95  |.........'.7y)..|
+00000010  8c 13 0f f0 6e 8b 00 0c  1e 1a 36 73 b6 96 ad e1  |....n.....6s....|
+00000020  40 80 6d 68 f3 41 a9 a1  85 ca 86 81 73 6c fc 49  |@.mh.A......sl.I|
+00000030  b4 61 76 27 0f cd 22 5f  7e a7 c1 e3 13 f6 2e da  |.av'.."_~.......|
+00000040  1a 15 57 1a f1 b0 be 6d  55 44 78 95 62 82 ff 6e  |..W....mUDx.b..n|
+00000050  bb 70 ea 24 2c bf e2 14  48 3a 07 9a 30 3a a8 88  |.p.$,...H:..0:..|
+00000060  8b d6 b4 62 28 cb 30 94  54 f6 9c 15 34 e9 c4 d2  |...b(.0.T...4...|
+00000070  e3 42 cf 79 1f 96 34 f3  4c 9f f2 df 6e 70 4f cd  |.B.y..4.L...npO.|
+00000080  68 ae e2 2c d5 b7 f3 37  86 0a f5 7c af 32 16 03  |h..,...7...|.2..|
+00000090  03 02 89 86 be df d2 27  8b 37 7a 66 a9 20 cf 95  |.......'.7zf. ..|
+000000a0  d1 c9 3c c6 bc 53 16 01  e2 78 7e 2b 4d 45 20 d8  |..<..S...x~+ME .|
+000000b0  be da 93 9f 61 0b 34 25  f8 42 aa 0e b7 c5 a7 7a  |....a.4%.B.....z|
+000000c0  99 23 b5 a5 0b 39 37 48  2d 66 21 8a bd 41 11 e5  |.#...97H-f!..A..|
+000000d0  79 5f 5d c1 9b 4f c2 0c  fc a4 b9 ad 82 7e 7e 5b  |y_]..O.......~~[|
+000000e0  f6 95 46 eb b2 9e 9c 2d  58 7e c7 90 2c c4 7f 1c  |..F....-X~..,...|
+000000f0  cf 32 86 37 ec ab 60 71  ee 82 2b a2 95 61 8f 31  |.2.7..`q..+..a.1|
+00000100  99 2d c7 f4 5f 29 e8 b6  c3 f4 81 4f 2c b6 2c 67  |.-.._).....O,.,g|
+00000110  70 e5 cf d1 00 77 34 28  dc 61 cf e1 78 10 5e 64  |p....w4(.a..x.^d|
+00000120  17 f7 2b 3e 74 2c 8f 42  d5 a8 c2 4e 11 48 0f 0a  |..+>t,.B...N.H..|
+00000130  3f 8a ea 0f 37 f5 da 8f  7f 7c 61 b3 98 d9 69 80  |?...7....|a...i.|
+00000140  b5 1e c6 5c 01 ff e3 8e  45 a1 7a cb ee ea 12 d3  |...\....E.z.....|
+00000150  d7 56 2e 33 8c 55 a5 94  84 f7 a1 a4 fa f3 71 f4  |.V.3.U........q.|
+00000160  a3 15 f0 7e 44 c7 32 65  86 39 93 b7 df ab 6b 94  |...~D.2e.9....k.|
+00000170  df 6d d8 31 72 ba d9 7b  b6 8a 68 b1 c8 da e1 a0  |.m.1r..{..h.....|
+00000180  4f 0f 06 6a 52 78 6e a1  57 2f 2b 6b 10 5b c1 57  |O..jRxn.W/+k.[.W|
+00000190  d0 92 23 bf dc 95 f1 83  66 ce 6f ef c5 22 22 24  |..#.....f.o..""$|
+000001a0  80 bd 2f 38 ff de ec 86  8b ad 81 4e fe 31 65 54  |../8.......N.1eT|
+000001b0  19 94 ce 99 0f 6d 5b 1b  53 ba ad 65 a6 6a f6 27  |.....m[.S..e.j.'|
+000001c0  ba e0 b7 a9 8b 80 18 71  67 f7 6c 35 5f 69 c2 19  |.......qg.l5_i..|
+000001d0  08 27 03 45 5a 58 49 27  cf ec bf 18 e7 60 64 2b  |.'.EZXI'.....`d+|
+000001e0  47 9e 07 1a 49 ef 90 20  c7 f7 69 5c 46 92 ae 65  |G...I.. ..i\F..e|
+000001f0  fa 45 9f 3b a3 4e ed cb  d9 1f d9 26 18 1e bb 58  |.E.;.N.....&...X|
+00000200  16 cd a5 00 df 65 73 39  82 fd 98 29 de 45 8f 70  |.....es9...).E.p|
+00000210  56 e3 c6 0b 18 71 09 92  0e 69 4e b8 e7 23 4f 70  |V....q...iN..#Op|
+00000220  7a 89 06 c7 78 05 04 31  7f 77 5c 68 74 f0 45 76  |z...x..1.w\ht.Ev|
+00000230  e2 56 b2 de 34 e6 79 64  49 9a a8 3a b7 5b 4a d3  |.V..4.ydI..:.[J.|
+00000240  5e 6d 0b f3 fb 6d 0c 2f  61 d0 71 f4 0d ed 60 2f  |^m...m./a.q...`/|
+00000250  61 80 c9 9b b9 e5 89 f2  64 88 52 d6 d3 aa 72 6b  |a.......d.R...rk|
+00000260  66 18 ae e9 df 20 40 15  b5 73 ba ac 50 b1 27 99  |f.... @..s..P.'.|
+00000270  b3 17 97 56 0b 7d 25 8a  64 80 42 5c c8 b8 d5 98  |...V.}%.d.B\....|
+00000280  28 16 2b ce 45 65 3d fc  d8 c6 91 31 c2 d4 09 a3  |(.+.Ee=....1....|
+00000290  cf 92 85 63 36 cb e2 da  a3 66 fb 08 c9 bc 12 23  |...c6....f.....#|
+000002a0  c8 88 7d 46 22 98 40 01  bf fb 58 84 f2 8f ad 83  |..}F".@...X.....|
+000002b0  ed 79 b4 a8 3d e5 92 b7  b8 e1 d0 50 aa be 22 9c  |.y..=......P..".|
+000002c0  9c cb dc bd 65 59 41 3e  6f 53 89 02 30 b1 88 ca  |....eYA>oS..0...|
+000002d0  06 6d 8e b2 a6 75 6a d8  5a 19 65 de 27 c3 bf 70  |.m...uj.Z.e.'..p|
+000002e0  49 64 13 2d 19 5d 7a ec  91 a7 f6 82 92 7d e3 7e  |Id.-.]z......}.~|
+000002f0  d6 65 5b d4 eb ed 58 d7  cd 41 a2 b9 d3 9e e4 a0  |.e[...X..A......|
+00000300  92 bf 88 4f 0e 59 74 66  86 db 72 11 18 ad 81 24  |...O.Ytf..r....$|
+00000310  6e 43 38 24 23 fb db af  92 d8 1a 2d 16 03 03 00  |nC8$#......-....|
+00000320  e5 86 be df d2 27 8b 37  7b ce 01 b6 78 47 7d 3a  |.....'.7{...xG}:|
+00000330  ad 2e 03 8e 78 03 61 da  55 0e d4 fa 87 9d 20 25  |....x.a.U..... %|
+00000340  73 1f 3b 87 7b 02 c1 a3  af ce d5 b9 9e 29 91 1b  |s.;.{........)..|
+00000350  58 13 c9 bc 96 95 88 f8  67 43 03 25 a3 be 5e a6  |X.......gC.%..^.|
+00000360  1d ee 6e 70 4c b5 66 48  3d 7d 1a 58 8e 10 c0 68  |..npL.fH=}.X...h|
+00000370  6b d8 f1 dd 83 c5 d3 c8  81 c5 6d 72 68 50 41 6f  |k.........mrhPAo|
+00000380  f6 20 13 f8 72 fa 82 9a  25 e4 07 10 df b7 39 90  |. ..r...%.....9.|
+00000390  6a d7 d2 d7 a1 1c 31 4e  b6 7c 00 bc 4d b1 a1 ff  |j.....1N.|..M...|
+000003a0  d0 ae 42 b1 2d 3e 8b c9  43 f4 fa fc d4 71 8f 74  |..B.->..C....q.t|
+000003b0  37 23 1b bb 34 4e b6 e4  fe f1 1b ea da 08 e4 12  |7#..4N..........|
+000003c0  fd 50 23 f9 8a 2d 92 eb  f5 2b fc b4 e1 35 87 74  |.P#..-...+...5.t|
+000003d0  44 79 0b df 6a 14 eb 20  17 ab 5b 12 a7 19 a4 4e  |Dy..j.. ..[....N|
+000003e0  94 70 93 57 2d bd c2 54  88 fb 19 b7 82 28 ab db  |.p.W-..T.....(..|
+000003f0  ca a9 19 5d 36 1b d6 fc  7d 41 2c 5b 76 ec 90 72  |...]6...}A,[v..r|
+00000400  47 5b c4 ae 59 a6 16 03  03 00 46 86 be df d2 27  |G[..Y.....F....'|
+00000410  8b 37 7c ed db 59 c6 0b  4e 52 c9 bc 7a 81 ed 20  |.7|..Y..NR..z.. |
+00000420  00 55 02 76 15 49 9b 0b  f2 81 c2 f7 25 51 61 9d  |.U.v.I......%Qa.|
+00000430  48 e3 d2 6f 08 ea 0c 9b  26 cc 3b 52 58 ef a0 1f  |H..o....&.;RX...|
+00000440  09 c3 ca e8 c2 6c 13 86  b1 94 04 f1 65 e2 de 4c  |.....l......e..L|
+00000450  7c                                                |||
+>>> Flow 9 (client to server)
+00000000  16 03 03 02 89 00 00 00  00 00 00 00 03 3c 0f 09  |.............<..|
+00000010  9e dc 39 b8 be ab ca 53  74 05 93 12 a4 e7 bb 56  |..9....St......V|
+00000020  9f e1 9f 2a 09 7d e1 74  89 ee b3 99 3c 91 c6 38  |...*.}.t....<..8|
+00000030  7e 0c 5e 2d 1f 7d bd cd  1a d1 16 ab af 94 08 c6  |~.^-.}..........|
+00000040  74 e3 16 12 0e 9b bc 91  95 6d 01 fd 10 00 12 c6  |t........m......|
+00000050  03 96 92 08 df 50 89 ba  5c 25 ce 31 d8 b1 84 8a  |.....P..\%.1....|
+00000060  7d 6c cf 7f e6 9a e4 08  17 cc b8 f2 c9 8f e8 4b  |}l.............K|
+00000070  ab 44 4f e9 63 8c 93 71  b1 70 4a f4 29 5f ef 45  |.DO.c..q.pJ.)_.E|
+00000080  68 e1 0e 31 a0 4c 96 8c  65 03 f3 48 24 48 d4 d7  |h..1.L..e..H$H..|
+00000090  93 d1 17 39 8d 97 e8 d8  59 08 4b 46 82 cf a3 99  |...9....Y.KF....|
+000000a0  55 36 65 a9 d8 df db d5  65 78 52 38 c2 2a 1e ec  |U6e.....exR8.*..|
+000000b0  65 6a f5 d5 4c 81 0c f6  e6 77 b2 68 d4 6c 32 05  |ej..L....w.h.l2.|
+000000c0  ef f4 ee 0b e1 83 d0 3a  cf a0 06 f2 cc 61 62 5e  |.......:.....ab^|
+000000d0  fa b4 19 c7 e2 99 c1 cf  02 a1 01 3d 6a e0 be 9f  |...........=j...|
+000000e0  82 cd e5 c8 ac e2 3e 6d  0f 60 a4 e9 9b ca cf c9  |......>m.`......|
+000000f0  c1 fe 2d ef 29 ed f9 c3  11 03 9f 76 66 71 ef 24  |..-.)......vfq.$|
+00000100  5f d3 29 aa 6a e1 0c b1  58 7a f3 df 92 e8 61 e2  |_.).j...Xz....a.|
+00000110  41 43 ad 9d 55 a0 b0 a3  20 8d 2c 8f 34 e6 ab d3  |AC..U... .,.4...|
+00000120  37 80 9e cb 27 91 69 0a  ba 33 05 a1 7f 4d 7f 63  |7...'.i..3...M.c|
+00000130  ed 6a c1 72 43 ec 6a 6c  ac b7 87 bb 81 6e 06 fa  |.j.rC.jl.....n..|
+00000140  68 7a c9 33 28 59 ed 74  87 a1 6a 24 06 02 c0 21  |hz.3(Y.t..j$...!|
+00000150  71 b0 27 f9 6e b3 7e 30  e9 e0 df c2 5d 63 2a dd  |q.'.n.~0....]c*.|
+00000160  9d e9 9c 4f 47 66 68 7e  e4 8c 87 b7 f0 a8 3d b8  |...OGfh~......=.|
+00000170  36 39 3e 4c 9f 55 e7 bb  c7 3e 34 36 54 19 41 33  |69>L.U...>46T.A3|
+00000180  61 e6 9a ae c6 91 1d fa  2d 8c 45 95 5f 95 36 79  |a.......-.E._.6y|
+00000190  e9 59 7e 81 cd 7e 9e 01  fe 85 eb c8 ed 4e 93 c6  |.Y~..~.......N..|
+000001a0  53 76 2d 5c 72 50 22 16  04 15 c2 cf 19 07 e6 73  |Sv-\rP"........s|
+000001b0  74 d0 7b bb 68 c3 29 39  bc ab 1b 4c c9 5a 36 73  |t.{.h.)9...L.Z6s|
+000001c0  55 47 7a c8 4a a7 45 fe  f3 a9 94 6e ea ea cc 7d  |UGz.J.E....n...}|
+000001d0  d1 de f4 82 4c 14 84 f0  58 09 56 25 83 7a 23 71  |....L...X.V%.z#q|
+000001e0  a1 63 e3 4e 13 78 68 41  a1 9a 55 ec 9e 37 ee c2  |.c.N.xhA..U..7..|
+000001f0  7d 3f 8f 91 00 30 f2 ca  7b 13 b7 e7 fe 85 c5 aa  |}?...0..{.......|
+00000200  5e e3 97 2c cb d5 13 1e  83 3d c9 2a b1 21 f1 58  |^..,.....=.*.!.X|
+00000210  7d 09 32 31 d6 fd 89 26  ff 72 3c f7 c4 fe 99 33  |}.21...&.r<....3|
+00000220  41 82 76 05 b9 14 b1 b0  3c 41 02 74 a8 1d dd 80  |A.v.....<A.t....|
+00000230  38 67 25 01 39 f7 36 fa  e4 1c 7d 2f c9 7e 21 0a  |8g%.9.6...}/.~!.|
+00000240  30 77 1e ff fc 8a 31 ac  ee 91 f0 2c b1 9a b7 5e  |0w....1....,...^|
+00000250  26 d0 7a 9d b4 9e 53 6b  dd a6 5e 7b f0 45 99 9b  |&.z...Sk..^{.E..|
+00000260  2b 69 90 d4 dd 1a d0 b5  13 90 11 ac 01 f0 2f 94  |+i............/.|
+00000270  5b 59 7e 7a 40 22 3a b0  d4 24 92 7d 94 bf 34 91  |[Y~z@":..$.}..4.|
+00000280  f6 b9 cc c9 e5 de d3 67  6d 83 97 ee 8f 48 16 03  |.......gm....H..|
+00000290  03 00 5e 00 00 00 00 00  00 00 04 dc 6f 41 98 23  |..^.........oA.#|
+000002a0  d7 70 80 24 74 46 c8 45  e1 2f 43 1d b8 66 4d 0a  |.p.$tF.E./C..fM.|
+000002b0  03 0e d6 01 8b 92 f7 76  c1 2c 32 6c 65 60 da ab  |.......v.,2le`..|
+000002c0  0b 12 6d 30 1c cf de e7  ec a7 12 f9 df 6c b4 42  |..m0.........l.B|
+000002d0  e7 d9 6e 6e f3 1c 10 ee  39 47 7f ec 7c ec 68 68  |..nn....9G..|.hh|
+000002e0  e8 b2 70 a2 67 61 e0 b3  68 b5 91 9f 1a e0 c5 af  |..p.ga..h.......|
+000002f0  e3 16 03 03 00 a0 00 00  00 00 00 00 00 05 6b 56  |..............kV|
+00000300  3d 5e 4e f1 2c 30 e2 91  24 5c b1 5f d3 7d 3e dc  |=^N.,0..$\._.}>.|
+00000310  ba 98 e1 9f 72 98 2b 0e  11 07 d1 ea 14 d5 73 25  |....r.+.......s%|
+00000320  d2 cf 8e bc a5 ea 93 a7  32 ab 94 83 1e ea c5 62  |........2......b|
+00000330  06 79 bb ab 4c a0 cf fb  51 3b 7b f0 11 5e ae 50  |.y..L...Q;{..^.P|
+00000340  23 cb ff 86 03 3d a5 66  b9 c4 35 c2 12 f2 98 85  |#....=.f..5.....|
+00000350  77 ba af 3b d5 dd f2 cd  58 09 29 26 08 cd 4a ed  |w..;....X.)&..J.|
+00000360  ac af 57 ab 27 1a 40 ef  10 57 d1 ad 06 34 be ed  |..W.'.@..W...4..|
+00000370  fe 88 1d 09 4a 81 8a da  e7 ef fa 27 71 ab 2b 3f  |....J......'q.+?|
+00000380  21 91 5f 1a dc 50 a4 f0  58 bd aa af 75 4e 25 2a  |!._..P..X...uN%*|
+00000390  2c 55 e5 57 c6 ab 14 03  03 00 19 00 00 00 00 00  |,U.W............|
+000003a0  00 00 06 5d 8a 3e 8e 55  e4 9d c0 6a de 91 c6 96  |...].>.U...j....|
+000003b0  6e 17 54 a5 16 03 03 00  28 00 00 00 00 00 00 00  |n.T.....(.......|
+000003c0  00 d5 45 5d 11 af e2 b6  f1 a8 e5 ed 58 80 54 ce  |..E]........X.T.|
+000003d0  b3 db dc 97 b3 86 c0 83  f9 3b 7c b5 ad 21 f8 cf  |.........;|..!..|
+000003e0  9a                                                |.|
+>>> Flow 10 (server to client)
+00000000  14 03 03 00 19 86 be df  d2 27 8b 37 7d 85 70 b7  |.........'.7}.p.|
+00000010  a7 98 89 36 01 b4 a8 6f  cb 14 0f dd ac 08 16 03  |...6...o........|
+00000020  03 00 28 75 41 a9 ef 1c  88 59 4e 84 15 29 a4 75  |..(uA....YN..).u|
+00000030  e6 66 01 3f a1 b7 ff 69  04 b6 08 99 c9 5e 57 60  |.f.?...i.....^W`|
+00000040  ea 76 21 94 06 e4 32 95  e1 4c d7 17 03 03 00 21  |.v!...2..L.....!|
+00000050  75 41 a9 ef 1c 88 59 4f  c8 5d 4e bd 42 52 ec 50  |uA....YO.]N.BR.P|
+00000060  2f 28 4f 87 da bc f0 df  a8 93 14 b7 6f a0 7f a2  |/(O.........o...|
+00000070  c5                                                |.|
+>>> Flow 11 (client to server)
+00000000  15 03 03 00 1a 00 00 00  00 00 00 00 01 92 8a f2  |................|
+00000010  9a d1 c9 1e 68 15 2d 6b  9a a7 f8 21 78 87 89     |....h.-k...!x..|
diff --git a/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateTwice b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateTwice
new file mode 100644
index 00000000000..185dc6528c9
--- /dev/null
+++ b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateTwice
@@ -0,0 +1,409 @@
+>>> Flow 1 (client to server)
+00000000  16 03 01 00 85 01 00 00  81 03 03 00 00 00 00 00  |................|
+00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 22 c0 2f  |............."./|
+00000030  c0 2b c0 30 c0 2c c0 11  c0 07 c0 13 c0 09 c0 14  |.+.0.,..........|
+00000040  c0 0a 00 9c 00 9d 00 05  00 2f 00 35 c0 12 00 0a  |........./.5....|
+00000050  01 00 00 36 00 05 00 05  01 00 00 00 00 00 0a 00  |...6............|
+00000060  08 00 06 00 17 00 18 00  19 00 0b 00 02 01 00 00  |................|
+00000070  0d 00 0e 00 0c 04 01 04  03 05 01 05 03 02 01 02  |................|
+00000080  03 ff 01 00 01 00 00 12  00 00                    |..........|
+>>> Flow 2 (server to client)
+00000000  16 03 03 00 59 02 00 00  55 03 03 bb b7 b5 ee 8b  |....Y...U.......|
+00000010  b7 92 40 96 01 65 93 09  a0 63 77 b3 35 74 0a 73  |..@..e...cw.5t.s|
+00000020  db e8 4a 9c d4 95 4b 2a  f9 43 1e 20 d6 5a ed d1  |..J...K*.C. .Z..|
+00000030  05 f0 61 aa 45 ae 0e 92  03 87 1b a6 0a 1a 83 a1  |..a.E...........|
+00000040  bd 4f c3 81 79 e8 56 10  5d 08 7b 6d c0 2f 00 00  |.O..y.V.].{m./..|
+00000050  0d ff 01 00 01 00 00 0b  00 04 03 00 01 02 16 03  |................|
+00000060  03 02 71 0b 00 02 6d 00  02 6a 00 02 67 30 82 02  |..q...m..j..g0..|
+00000070  63 30 82 01 cc a0 03 02  01 02 02 09 00 a2 73 00  |c0............s.|
+00000080  0c 81 00 cb f3 30 0d 06  09 2a 86 48 86 f7 0d 01  |.....0...*.H....|
+00000090  01 0b 05 00 30 2b 31 17  30 15 06 03 55 04 0a 13  |....0+1.0...U...|
+000000a0  0e 47 6f 6f 67 6c 65 20  54 45 53 54 49 4e 47 31  |.Google TESTING1|
+000000b0  10 30 0e 06 03 55 04 03  13 07 47 6f 20 52 6f 6f  |.0...U....Go Roo|
+000000c0  74 30 1e 17 0d 31 35 30  31 30 31 30 30 30 30 30  |t0...15010100000|
+000000d0  30 5a 17 0d 32 35 30 31  30 31 30 30 30 30 30 30  |0Z..250101000000|
+000000e0  5a 30 26 31 17 30 15 06  03 55 04 0a 13 0e 47 6f  |Z0&1.0...U....Go|
+000000f0  6f 67 6c 65 20 54 45 53  54 49 4e 47 31 0b 30 09  |ogle TESTING1.0.|
+00000100  06 03 55 04 03 13 02 47  6f 30 81 9f 30 0d 06 09  |..U....Go0..0...|
+00000110  2a 86 48 86 f7 0d 01 01  01 05 00 03 81 8d 00 30  |*.H............0|
+00000120  81 89 02 81 81 00 af 87  88 f6 20 1b 95 65 6c 14  |.......... ..el.|
+00000130  ab 44 05 af 3b 45 14 e3  b7 6d fd 00 63 4d 95 7f  |.D..;E...m..cM..|
+00000140  fe 6a 62 35 86 c0 4a f9  18 7c f6 aa 25 5e 7a 64  |.jb5..J..|..%^zd|
+00000150  31 66 00 ba f4 8e 92 af  c7 6b d8 76 d4 f3 5f 41  |1f.......k.v.._A|
+00000160  cb 6e 56 15 97 1b 97 c1  3c 12 39 21 66 3d 2b 16  |.nV.....<.9!f=+.|
+00000170  d1 bc db 1c c0 a7 da b7  ca ad ba da cb d5 21 50  |..............!P|
+00000180  ec de 8d ab d1 6b 81 4b  89 02 f3 c4 be c1 6c 89  |.....k.K......l.|
+00000190  b1 44 84 bd 21 d1 04 7d  9d 16 4d f9 82 15 f6 ef  |.D..!..}..M.....|
+000001a0  fa d6 09 47 f2 fb 02 03  01 00 01 a3 81 93 30 81  |...G..........0.|
+000001b0  90 30 0e 06 03 55 1d 0f  01 01 ff 04 04 03 02 05  |.0...U..........|
+000001c0  a0 30 1d 06 03 55 1d 25  04 16 30 14 06 08 2b 06  |.0...U.%..0...+.|
+000001d0  01 05 05 07 03 01 06 08  2b 06 01 05 05 07 03 02  |........+.......|
+000001e0  30 0c 06 03 55 1d 13 01  01 ff 04 02 30 00 30 19  |0...U.......0.0.|
+000001f0  06 03 55 1d 0e 04 12 04  10 12 50 8d 89 6f 1b d1  |..U.......P..o..|
+00000200  dc 54 4d 6e cb 69 5e 06  f4 30 1b 06 03 55 1d 23  |.TMn.i^..0...U.#|
+00000210  04 14 30 12 80 10 bf 3d  b6 a9 66 f2 b8 40 cf ea  |..0....=..f..@..|
+00000220  b4 03 78 48 1a 41 30 19  06 03 55 1d 11 04 12 30  |..xH.A0...U....0|
+00000230  10 82 0e 65 78 61 6d 70  6c 65 2e 67 6f 6c 61 6e  |...example.golan|
+00000240  67 30 0d 06 09 2a 86 48  86 f7 0d 01 01 0b 05 00  |g0...*.H........|
+00000250  03 81 81 00 92 7c af 91  55 12 18 96 59 31 a6 48  |.....|..U...Y1.H|
+00000260  40 d5 2d d5 ee bb 02 a0  f5 c2 1e 7c 9b b3 30 7d  |@.-........|..0}|
+00000270  3c dc 76 da 4f 3d c0 fa  ae 2d 33 24 6b 03 7b 1b  |<.v.O=...-3$k.{.|
+00000280  67 59 11 21 b5 11 bc 77  b9 d9 e0 6e a8 2d 2e 35  |gY.!...w...n.-.5|
+00000290  fa 64 5f 22 3e 63 10 6b  be ff 14 86 6d 0d f0 15  |.d_">c.k....m...|
+000002a0  31 a8 14 38 1e 3b 84 87  2c cb 98 ed 51 76 b9 b1  |1..8.;..,...Qv..|
+000002b0  4f dd db 9b 84 04 86 40  fa 51 dd ba b4 8d eb e3  |O......@.Q......|
+000002c0  46 de 46 b9 4f 86 c7 f9  a4 c2 41 34 ac cc f6 ea  |F.F.O.....A4....|
+000002d0  b0 ab 39 18 16 03 03 00  cd 0c 00 00 c9 03 00 17  |..9.............|
+000002e0  41 04 b5 fe 7d 68 cd 5a  b7 bf 61 10 81 dc 92 23  |A...}h.Z..a....#|
+000002f0  d0 82 13 fb 71 6f 39 48  f9 87 f8 f7 a0 3a cd 18  |....qo9H.....:..|
+00000300  85 d7 4d 66 88 9d 39 8d  6d 53 a1 a3 0d 00 b0 0f  |..Mf..9.mS......|
+00000310  14 64 1b 72 2d 89 5c 93  6f 3c ed c9 82 20 3d 2f  |.d.r-.\.o<... =/|
+00000320  d0 7f 04 01 00 80 42 24  14 6e cf 78 ea 30 90 1e  |......B$.n.x.0..|
+00000330  4e 99 bf ca 98 9c 2f 24  98 c2 a2 b3 f8 34 49 22  |N...../$.....4I"|
+00000340  35 16 11 03 79 3b a8 10  a3 fa d8 5e 17 9d f9 50  |5...y;.....^...P|
+00000350  0a 3b 0b b5 b2 0f 90 18  c1 f5 6f 89 84 04 e2 f0  |.;........o.....|
+00000360  b0 04 2f 3e 78 d3 de 31  9e 6e 3b b8 c7 f5 cc 4f  |../>x..1.n;....O|
+00000370  4e ad fe 76 d2 6d 23 31  94 56 b1 d8 df 0d 9b c5  |N..v.m#1.V......|
+00000380  f7 9e 9c a7 2a 47 e4 c8  20 08 fc 6c d5 29 cd 36  |....*G.. ..l.).6|
+00000390  88 83 c5 59 33 6d 1f 0b  f9 98 65 fa cb f7 89 2d  |...Y3m....e....-|
+000003a0  90 3a 40 8a 31 7e 16 03  03 00 04 0e 00 00 00     |.:@.1~.........|
+>>> Flow 3 (client to server)
+00000000  16 03 03 00 46 10 00 00  42 41 04 1e 18 37 ef 0d  |....F...BA...7..|
+00000010  19 51 88 35 75 71 b5 e5  54 5b 12 2e 8f 09 67 fd  |.Q.5uq..T[....g.|
+00000020  a7 24 20 3e b2 56 1c ce  97 28 5e f8 2b 2d 4f 9e  |.$ >.V...(^.+-O.|
+00000030  f1 07 9f 6c 4b 5b 83 56  e2 32 42 e9 58 b6 d7 49  |...lK[.V.2B.X..I|
+00000040  a6 b5 68 1a 41 03 56 6b  dc 5a 89 14 03 03 00 01  |..h.A.Vk.Z......|
+00000050  01 16 03 03 00 28 00 00  00 00 00 00 00 00 fa e7  |.....(..........|
+00000060  ff 47 50 7a 68 0d 20 f6  9f 2a b5 bc f4 21 c1 72  |.GPzh. ..*...!.r|
+00000070  07 4c e5 07 2c 07 e5 1e  d7 fa 07 01 83 68        |.L..,........h|
+>>> Flow 4 (server to client)
+00000000  14 03 03 00 01 01 16 03  03 00 28 b7 93 18 5b 36  |..........(...[6|
+00000010  18 ce 97 17 75 40 15 17  1f 0e 0d 99 fd 66 fa 89  |....u@.......f..|
+00000020  db b7 97 95 a9 45 90 07  6e 82 0e 67 4f 01 58 ec  |.....E..n..gO.X.|
+00000030  94 d7 ad                                          |...|
+>>> Flow 5 (client to server)
+00000000  17 03 03 00 1e 00 00 00  00 00 00 00 01 21 2b 7b  |.............!+{|
+00000010  62 ac e4 37 d6 77 19 89  77 1c 6a ce 40 c1 9d 71  |b..7.w..w.j.@..q|
+00000020  5a 23 f0                                          |Z#.|
+>>> Flow 6 (server to client)
+00000000  16 03 03 00 1c b7 93 18  5b 36 18 ce 98 4a 49 69  |........[6...JIi|
+00000010  f4 dd 35 f2 93 3b c6 4e  d5 25 51 34 38 23 ea 74  |..5..;.N.%Q48#.t|
+00000020  84                                                |.|
+>>> Flow 7 (client to server)
+00000000  16 03 03 00 a9 00 00 00  00 00 00 00 02 65 09 7a  |.............e.z|
+00000010  d5 9b 32 0b cd 10 ea 2c  b6 d8 be ce db 3f a4 38  |..2....,.....?.8|
+00000020  a7 37 a3 95 ed 05 a7 c1  28 69 7a 13 50 07 ab 19  |.7......(iz.P...|
+00000030  52 d7 29 fe 49 80 f0 ef  ea 17 ac 20 f9 62 51 72  |R.).I...... .bQr|
+00000040  8d c0 17 62 03 cf bb 80  f8 6f 1b 74 f1 85 45 96  |...b.....o.t..E.|
+00000050  49 55 56 b0 7a dd 9b 5a  f1 3f 1a e7 96 cd 21 ec  |IUV.z..Z.?....!.|
+00000060  85 6f b9 9d 0f e3 f6 55  9b b8 a7 e1 77 ad 53 0b  |.o.....U....w.S.|
+00000070  98 90 ac 5d cf 31 0f 86  69 04 d8 e9 5e fc ea a8  |...].1..i...^...|
+00000080  a8 b7 a2 d8 0f ea 4f e5  ac f2 b2 c0 59 29 ba 53  |......O.....Y).S|
+00000090  af 1e 81 08 be 02 46 a7  b8 6f 2a b4 86 47 5d 8e  |......F..o*..G].|
+000000a0  72 a6 64 84 7e 76 31 9c  31 fb 59 b7 da 15        |r.d.~v1.1.Y...|
+>>> Flow 8 (server to client)
+00000000  16 03 03 00 89 b7 93 18  5b 36 18 ce 99 4a 72 26  |........[6...Jr&|
+00000010  ab cb a4 70 60 0f 7a 02  62 28 f3 10 54 77 a7 33  |...p`.z.b(..Tw.3|
+00000020  32 a6 29 c8 8d 18 48 8f  9d 45 6e 7e 06 07 ca b3  |2.)...H..En~....|
+00000030  b6 45 eb ac f2 41 f1 d9  19 9e 30 1f c0 18 40 1c  |.E...A....0...@.|
+00000040  55 09 4d f2 23 75 2f 2f  c8 b7 46 63 05 d1 73 c0  |U.M.#u//..Fc..s.|
+00000050  02 71 de 5e 4a 84 92 3d  9a b9 68 62 31 91 7d 23  |.q.^J..=..hb1.}#|
+00000060  43 e3 4b 00 98 2e 01 12  f4 1f fa 4c aa 91 a0 ca  |C.K........L....|
+00000070  9c a0 d9 6b 7f 5c b3 f4  8d e2 3a 54 eb e9 82 44  |...k.\....:T...D|
+00000080  21 54 ac 85 86 39 b8 df  23 64 2a 0c 3e 1d 16 03  |!T...9..#d*.>...|
+00000090  03 02 89 b7 93 18 5b 36  18 ce 9a 1c ae 99 12 58  |......[6.......X|
+000000a0  12 fa ef da 77 04 7f b5  42 68 b1 59 64 50 92 2b  |....w...Bh.YdP.+|
+000000b0  a0 21 b7 b3 4c f8 c2 cc  75 5a d0 85 50 95 f4 1b  |.!..L...uZ..P...|
+000000c0  c9 b2 1f 53 94 4c fd 6d  18 ad 1a 0d 24 9f fb 4c  |...S.L.m....$..L|
+000000d0  19 13 5a 74 f2 e2 59 dd  1b d8 67 bc d9 d0 da ab  |..Zt..Y...g.....|
+000000e0  a7 7f 8e ca e0 09 28 59  18 8d a1 8a c9 c3 2e 76  |......(Y.......v|
+000000f0  b9 0d 2f 56 5f c4 77 07  17 ac 62 26 a1 91 50 ee  |../V_.w...b&..P.|
+00000100  60 45 aa a0 8a d9 1a 13  65 68 c8 cf ca 0c 50 3e  |`E......eh....P>|
+00000110  9f 39 62 02 12 ea b4 ed  e2 6c 0e 28 32 d7 fb ec  |.9b......l.(2...|
+00000120  fc 6d e4 0a 14 1d 88 00  a8 c0 57 1e be 78 fd 18  |.m........W..x..|
+00000130  6e 40 70 37 2e f5 3b 52  59 03 02 bf 27 18 c8 00  |n@p7..;RY...'...|
+00000140  58 8f 5e d8 a8 7c 4c 54  83 4a fe f3 dc f8 19 2a  |X.^..|LT.J.....*|
+00000150  00 ed 96 93 0e e4 45 58  8f 41 99 0d 93 f5 6c a4  |......EX.A....l.|
+00000160  4e 62 f2 4b 9a cb 69 30  5a 4b 36 45 f2 d2 c1 62  |Nb.K..i0ZK6E...b|
+00000170  f9 1c c4 c3 b2 94 b3 17  1a ed d8 57 ba b7 79 a1  |...........W..y.|
+00000180  a2 2e 5a 18 79 36 0b 54  ee 2c 2c 3b 62 96 5d e5  |..Z.y6.T.,,;b.].|
+00000190  3c 74 0e be 52 6f 06 7c  93 05 86 0f d6 1d d0 ee  |<t..Ro.|........|
+000001a0  f9 ac 67 50 a6 d3 36 f7  5f 0b 3f 44 3b fc 4b 79  |..gP..6._.?D;.Ky|
+000001b0  b7 29 04 6c 37 18 2a 04  bf f4 3e 1a 53 f3 93 e5  |.).l7.*...>.S...|
+000001c0  f2 b7 b1 4b ed 19 5a 2f  40 d1 f2 91 49 0b 8b f6  |...K..Z/@...I...|
+000001d0  21 0b 20 01 ce 0f a8 f1  44 3f 5e b1 89 1a 15 9f  |!. .....D?^.....|
+000001e0  4c c5 93 6b 68 93 ab 67  b5 1d 10 fa 22 53 e3 0f  |L..kh..g...."S..|
+000001f0  c7 63 d0 32 b7 52 c6 2e  b7 47 a4 1a b4 ab 35 a9  |.c.2.R...G....5.|
+00000200  b0 0e cd f6 8c e7 54 6c  77 7b 5c 6c c2 b3 02 89  |......Tlw{\l....|
+00000210  74 f7 b1 61 91 dc 01 3a  68 d9 81 78 21 95 b1 67  |t..a...:h..x!..g|
+00000220  36 2d 2a d6 c4 96 0d 7b  e0 44 83 cd 52 e4 05 36  |6-*....{.D..R..6|
+00000230  a4 1d 2a 24 e8 cc 76 d7  66 2f 32 ef 8f 70 ef 26  |..*$..v.f/2..p.&|
+00000240  90 73 2e e6 b4 53 91 13  5b 5e 15 51 15 56 e9 43  |.s...S..[^.Q.V.C|
+00000250  22 9a b6 55 3d 94 00 35  73 41 12 fc 8a 0b fd 89  |"..U=..5sA......|
+00000260  7c 00 14 0d b8 f6 76 d0  ac 33 1d e4 73 49 e9 a2  ||.....v..3..sI..|
+00000270  09 69 e1 f1 a7 92 48 ee  2e fc ef 13 09 7c a7 72  |.i....H......|.r|
+00000280  eb 4c 15 39 17 6e cd 71  c0 e9 48 06 43 09 19 39  |.L.9.n.q..H.C..9|
+00000290  72 b0 9c f8 0e 75 af a8  eb 25 96 36 75 68 16 8f  |r....u...%.6uh..|
+000002a0  e8 f6 66 56 66 63 b0 52  47 74 55 af c8 7a 07 dc  |..fVfc.RGtU..z..|
+000002b0  d0 8b bf 51 6e bc 77 fa  8a 03 43 0c 5a 47 fb c7  |...Qn.w...C.ZG..|
+000002c0  be b3 ef b5 ad 24 48 40  6c 4b 03 41 dd 7c 3e 6e  |.....$H@lK.A.|>n|
+000002d0  25 01 4b 45 ce ad d7 23  3a 6c 33 0b f1 7a 44 07  |%.KE...#:l3..zD.|
+000002e0  7e c8 bd 52 a5 a8 30 91  95 3e 4d 42 07 67 57 fb  |~..R..0..>MB.gW.|
+000002f0  c0 4a ed 9f 76 21 8e df  fb f6 a4 0a 08 1e 5b c6  |.J..v!........[.|
+00000300  3e a3 8c 47 a4 4d 41 2b  e6 8f 42 43 cd ef a8 f1  |>..G.MA+..BC....|
+00000310  88 f2 b3 46 eb 8a 24 a3  98 a2 d7 d2 16 03 03 00  |...F..$.........|
+00000320  e5 b7 93 18 5b 36 18 ce  9b 62 57 ae 22 62 34 88  |....[6...bW."b4.|
+00000330  41 e1 7e 2a 4a 07 b4 b8  aa 80 32 f5 93 4c 58 79  |A.~*J.....2..LXy|
+00000340  82 51 d4 b8 c8 5b d2 99  a3 18 43 aa c2 14 bf 65  |.Q...[....C....e|
+00000350  e8 90 8d 46 69 d5 fa 34  e4 1a 47 06 dc 1a ae e9  |...Fi..4..G.....|
+00000360  40 b2 2e 7e 5e 74 f7 72  4d a9 e2 b7 52 b4 bb dc  |@..~^t.rM...R...|
+00000370  06 e6 50 7e ef 42 8f 72  08 63 f9 ec 9e 13 36 0f  |..P~.B.r.c....6.|
+00000380  d4 95 72 2b ff a5 6d 4b  1b db d6 b3 25 50 f0 dd  |..r+..mK....%P..|
+00000390  e3 89 f5 c1 c0 3f aa 6c  f0 a7 30 5d 56 76 77 b6  |.....?.l..0]Vvw.|
+000003a0  24 8f 93 fd 49 8c 73 1e  f7 5c 5c 3a f3 0d 5e 89  |$...I.s..\\:..^.|
+000003b0  a4 bb 48 8a 82 ed 01 a6  2d eb b1 fe d2 6e 4e 88  |..H.....-....nN.|
+000003c0  1d 06 b6 f5 d8 41 86 40  fe 45 3e ef 35 9b 88 df  |.....A.@.E>.5...|
+000003d0  48 af e0 05 33 4e 13 15  8b b6 5a 8e 5c f8 2a 59  |H...3N....Z.\.*Y|
+000003e0  14 6d 4a 79 75 48 e4 9d  16 4f 6f 65 9c c3 40 1e  |.mJyuH...Ooe..@.|
+000003f0  7c 72 60 ce b9 f8 61 3b  ff 34 81 94 01 aa b3 59  ||r`...a;.4.....Y|
+00000400  72 d2 1e 5f fe 7f 16 03  03 00 46 b7 93 18 5b 36  |r.._......F...[6|
+00000410  18 ce 9c c8 c9 b2 10 f1  39 bb f0 80 a9 0b 68 76  |........9.....hv|
+00000420  2b 60 0b c5 f3 eb 16 72  b5 4c c9 42 96 39 bf c1  |+`.....r.L.B.9..|
+00000430  94 87 f0 47 80 34 11 e2  1c 4c fc 26 d6 4b 00 49  |...G.4...L.&.K.I|
+00000440  ef 73 00 4e ab 61 d6 1f  89 2c 7e f2 5c ea 6b 5c  |.s.N.a...,~.\.k\|
+00000450  50                                                |P|
+>>> Flow 9 (client to server)
+00000000  16 03 03 02 89 00 00 00  00 00 00 00 03 c2 d4 9b  |................|
+00000010  19 c8 b6 76 fb ef e4 b2  f7 97 c7 80 f5 e2 b4 3c  |...v...........<|
+00000020  bd b7 b8 25 da 54 52 a7  f8 38 0d 48 c0 13 19 82  |...%.TR..8.H....|
+00000030  17 3c ff d2 c0 8f bd 76  5d 16 39 db a7 51 3f b1  |.<.....v].9..Q?.|
+00000040  72 b6 59 e4 8c 6c f5 33  de 78 15 8d 64 cf 55 c6  |r.Y..l.3.x..d.U.|
+00000050  47 e3 0b 30 06 e1 6c 2d  e1 e0 7a e1 0a da dd 0d  |G..0..l-..z.....|
+00000060  60 5b 06 28 a8 94 14 a3  cc 91 96 8d 2b 71 af ff  |`[.(........+q..|
+00000070  c2 32 e2 19 77 96 f3 5b  53 3a d3 29 51 c2 54 98  |.2..w..[S:.)Q.T.|
+00000080  f3 00 8e 9a fe ef bb ea  06 27 58 54 3c c8 67 dc  |.........'XT<.g.|
+00000090  f3 41 01 77 de 25 b4 54  53 67 64 41 b3 ae 2b c2  |.A.w.%.TSgdA..+.|
+000000a0  57 cd 74 14 3c 46 a7 70  ec a8 bc 0e 05 46 ce fc  |W.t.<F.p.....F..|
+000000b0  c8 54 4d 23 25 b9 e0 45  fa 1e 1b 2c f1 d0 da 66  |.TM#%..E...,...f|
+000000c0  3c 00 e5 b3 f5 f9 ff 64  75 82 f9 dd c2 3f 42 46  |<......du....?BF|
+000000d0  27 ca 72 a2 f7 6c 4e bf  98 05 e6 99 b5 7b 60 33  |'.r..lN......{`3|
+000000e0  99 e8 7a 7c 91 41 64 cd  96 60 f2 f6 c8 bd 4f 35  |..z|.Ad..`....O5|
+000000f0  5f 6f 43 11 b0 94 3c 98  bc 58 15 7e 52 01 ba cf  |_oC...<..X.~R...|
+00000100  71 f4 0a fb 85 0a 24 13  0c 4a 53 55 77 92 91 cd  |q.....$..JSUw...|
+00000110  ce 39 7e 07 2f 4f ba 47  ca bd 67 5b ce 5a 04 03  |.9~./O.G..g[.Z..|
+00000120  ff 86 0a 82 80 b9 42 b8  4c e3 ce 73 b2 4a 5a 4b  |......B.L..s.JZK|
+00000130  f5 f2 44 d8 e5 01 30 c8  2e ce 4f 62 2d 34 9c d6  |..D...0...Ob-4..|
+00000140  57 20 db 37 20 66 03 b6  4d a7 0f 75 30 d8 ad 2f  |W .7 f..M..u0../|
+00000150  63 f7 4e 24 ec 68 e0 a2  a9 b1 3d 68 e5 c1 8b d8  |c.N$.h....=h....|
+00000160  19 dd 40 33 c6 5c 57 3b  22 5a 9c 24 fe 2f 92 54  |..@3.\W;"Z.$./.T|
+00000170  0f e8 85 74 06 72 59 ab  1d b8 5d 31 91 ed 05 51  |...t.rY...]1...Q|
+00000180  61 c6 43 3d 81 f4 47 c3  80 17 4d 1b 08 c4 85 1b  |a.C=..G...M.....|
+00000190  b7 37 b0 cf 5c 73 5f 56  0f 5a b5 21 21 46 e3 df  |.7..\s_V.Z.!!F..|
+000001a0  e6 cb 9d ac ab 16 c0 b1  b8 2a 4a 5b a7 2d 7a 00  |.........*J[.-z.|
+000001b0  9f 9d 76 57 ab 20 ea 80  8a 7a ca 14 45 d7 4e 1b  |..vW. ...z..E.N.|
+000001c0  c8 7c b8 c6 82 fc 40 b2  b4 7d f1 74 7d b5 2a 90  |.|....@..}.t}.*.|
+000001d0  01 83 d4 d1 26 63 d7 39  69 b1 33 5f 7e 54 de f7  |....&c.9i.3_~T..|
+000001e0  08 3d 62 3b da 57 0d d4  48 99 9a 3e 99 e5 b0 6b  |.=b;.W..H..>...k|
+000001f0  25 45 38 36 aa 7a bb 81  7d 0b dd 1d 50 c4 17 68  |%E86.z..}...P..h|
+00000200  4b a7 f7 2f d8 cd 97 a6  ea 24 9b 34 69 9e 7d ad  |K../.....$.4i.}.|
+00000210  6a 17 23 d8 36 61 cf 85  74 47 18 5b fd cd 72 ac  |j.#.6a..tG.[..r.|
+00000220  c2 a2 b4 53 e3 5d 25 f7  bb b6 95 99 a0 e5 05 38  |...S.]%........8|
+00000230  0a 52 32 f6 7d a6 30 5c  11 6b 8a 7b af ec a2 9b  |.R2.}.0\.k.{....|
+00000240  b8 f1 85 6d a8 b7 79 61  42 60 4a 35 73 fb d5 2c  |...m..yaB`J5s..,|
+00000250  1f 84 5c d9 c9 23 10 e8  a4 2c 56 fd f4 22 1a 7a  |..\..#...,V..".z|
+00000260  f3 b2 c5 69 8b c9 d1 d5  45 c8 65 59 fc ab d9 d3  |...i....E.eY....|
+00000270  7d ab c3 fe bc da 6d a3  cd 0c 83 32 70 65 c7 7f  |}.....m....2pe..|
+00000280  8c 83 c8 97 3e 7f 89 fc  11 7d 1c a5 fd 99 16 03  |....>....}......|
+00000290  03 00 5e 00 00 00 00 00  00 00 04 64 60 91 c0 fd  |..^........d`...|
+000002a0  3a 96 5a ac 5a 13 a9 9a  41 eb a0 6d 51 98 ee a8  |:.Z.Z...A..mQ...|
+000002b0  4d ee 90 c9 3e a5 15 ac  f3 6a c8 56 f3 20 c3 10  |M...>....j.V. ..|
+000002c0  e3 3a d1 ea b0 7d a7 21  ae 2c b1 fa 5c b8 c1 fa  |.:...}.!.,..\...|
+000002d0  d7 97 6e ea fd 09 53 46  db aa e4 39 31 00 c2 bb  |..n...SF...91...|
+000002e0  ad 36 10 cd e9 cb 46 31  7b 66 ee ce 0c a8 f9 c2  |.6....F1{f......|
+000002f0  0a 16 03 03 00 a0 00 00  00 00 00 00 00 05 6d a0  |..............m.|
+00000300  03 60 12 bb 06 89 0c 03  ad f7 36 f3 5c e4 c1 65  |.`........6.\..e|
+00000310  b2 26 c9 f5 87 85 f9 8f  2d 05 43 35 32 d7 0a a0  |.&......-.C52...|
+00000320  e5 16 7a 94 62 15 ed cc  8e 9f e3 10 8d e7 83 a2  |..z.b...........|
+00000330  ea e4 07 49 c9 df 1d 2b  6f b8 0f 67 31 22 44 9b  |...I...+o..g1"D.|
+00000340  65 77 99 78 f9 3e 14 67  3a 90 e5 5a c2 b5 1b ee  |ew.x.>.g:..Z....|
+00000350  db 20 73 8d 85 22 4d 79  6e e9 17 d0 b1 03 58 f3  |. s.."Myn.....X.|
+00000360  cf 1b f5 03 9a 75 1f 7a  3b 49 ee 67 04 da c4 fc  |.....u.z;I.g....|
+00000370  7a 62 a9 ff 26 4f 71 b2  7e e9 c7 78 96 74 1e 63  |zb..&Oq.~..x.t.c|
+00000380  eb 2b 2f 18 1f 19 cf 1e  89 73 39 9e f6 02 3d 31  |.+/......s9...=1|
+00000390  50 65 1f 80 19 26 14 03  03 00 19 00 00 00 00 00  |Pe...&..........|
+000003a0  00 00 06 82 62 df fd 51  9e be 21 0b 22 b6 c1 6d  |....b..Q..!."..m|
+000003b0  5c 90 ea c5 16 03 03 00  28 00 00 00 00 00 00 00  |\.......(.......|
+000003c0  00 d6 5f a7 05 2b 99 cc  7d fb d7 38 5e e3 31 a7  |.._..+..}..8^.1.|
+000003d0  c9 1c bd 7b c7 89 d0 e5  b5 93 78 d1 63 57 d2 76  |...{......x.cW.v|
+000003e0  38                                                |8|
+>>> Flow 10 (server to client)
+00000000  14 03 03 00 19 b7 93 18  5b 36 18 ce 9d 68 22 e1  |........[6...h".|
+00000010  d0 06 aa e5 87 f8 49 bc  38 d7 b9 38 85 97 16 03  |......I.8..8....|
+00000020  03 00 28 24 71 bf 67 14  d6 5e 29 1b de e6 f4 e0  |..($q.g..^).....|
+00000030  33 76 dc 66 c6 95 c0 3a  15 49 99 09 2f cf 6b 6b  |3v.f...:.I../.kk|
+00000040  a1 8f 1a e4 af 8d 1e 7f  02 b1 87 17 03 03 00 21  |...............!|
+00000050  24 71 bf 67 14 d6 5e 2a  61 7b 98 dd e8 52 b0 1e  |$q.g..^*a{...R..|
+00000060  28 46 28 de e2 22 65 6c  66 85 3a 1d bb 9e 76 a2  |(F(.."elf.:...v.|
+00000070  55 16 03 03 00 1c 24 71  bf 67 14 d6 5e 2b bb 84  |U.....$q.g..^+..|
+00000080  6d f0 1c d0 46 89 bb b2  09 96 dd 95 53 bf ac d7  |m...F.......S...|
+00000090  80 f1                                             |..|
+>>> Flow 11 (client to server)
+00000000  16 03 03 00 a9 00 00 00  00 00 00 00 01 61 12 ee  |.............a..|
+00000010  0a f2 5e e2 3d 3d 36 4c  14 10 20 aa 4d 8a 91 e4  |..^.==6L.. .M...|
+00000020  c2 b0 63 68 9e f5 71 b7  a4 ee 75 27 20 8c 2e 21  |..ch..q...u' ..!|
+00000030  f5 57 3d e9 9a 05 da 7b  a5 af 6a 17 10 8b eb 25  |.W=....{..j....%|
+00000040  8a 79 75 07 dc fe f5 7f  a5 e2 63 31 ee 55 ba c0  |.yu.......c1.U..|
+00000050  e6 3d de 03 36 2b 64 19  b1 1a b8 80 09 25 8c dd  |.=..6+d......%..|
+00000060  dd 59 c7 1d e7 40 20 ae  ca a9 b5 14 a7 57 f0 62  |.Y...@ ......W.b|
+00000070  71 88 a3 2c fc a4 50 dc  8b 85 22 20 38 c5 74 ea  |q..,..P..." 8.t.|
+00000080  ac 33 1d a3 c5 5c cc 10  62 fd c5 70 22 fa e3 73  |.3...\..b..p"..s|
+00000090  f3 bf 24 14 0d cb 7c 25  e4 74 6c fe c0 70 5e a0  |..$...|%.tl..p^.|
+000000a0  63 a7 e5 f2 6e d8 71 bd  7d b9 f0 b6 0b 70        |c...n.q.}....p|
+>>> Flow 12 (server to client)
+00000000  16 03 03 00 89 24 71 bf  67 14 d6 5e 2c 55 62 31  |.....$q.g..^,Ub1|
+00000010  5c a3 53 1a c3 2f 89 47  62 33 7e 24 cd ad a9 5b  |\.S../.Gb3~$...[|
+00000020  51 79 d8 08 08 ff 09 3c  41 c7 80 ed ec 5a 7a e4  |Qy.....<A....Zz.|
+00000030  71 e1 17 91 5e c1 80 58  35 c7 27 ca 62 74 cc d8  |q...^..X5.'.bt..|
+00000040  e8 35 86 97 bf 05 73 b9  3f ae 5b af 9a 14 88 4b  |.5....s.?.[....K|
+00000050  f9 6f a4 de 3d 45 c8 7b  0a b1 7a 81 3e 7c 02 b5  |.o..=E.{..z.>|..|
+00000060  e9 43 a5 64 88 59 f6 55  20 d1 09 39 cd 01 46 0f  |.C.d.Y.U ..9..F.|
+00000070  a2 06 f3 2b 45 14 b2 57  21 2c 2f a0 e5 db 02 99  |...+E..W!,/.....|
+00000080  e4 6b 1e 22 99 c9 ae 93  e4 67 89 d1 c6 6d 16 03  |.k.".....g...m..|
+00000090  03 02 89 24 71 bf 67 14  d6 5e 2d ce 6a 42 6b ce  |...$q.g..^-.jBk.|
+000000a0  07 4e ff 40 39 4b 00 c8  14 4c 76 e0 4d 09 41 c3  |.N.@9K...Lv.M.A.|
+000000b0  41 3a ca ac 28 06 01 80  e4 b8 73 a2 fc ea 8d 92  |A:..(.....s.....|
+000000c0  44 0e 43 3e d8 cb 8a 0c  a0 c1 5e 88 6d 6d 80 be  |D.C>......^.mm..|
+000000d0  9c 9f cc 20 7c fa 6f e4  1a a1 39 c2 a8 7d 04 85  |... |.o...9..}..|
+000000e0  75 5d c4 d3 6f df d7 3a  9d 83 c3 74 aa 49 df 34  |u]..o..:...t.I.4|
+000000f0  e0 41 ad a3 80 80 c3 29  44 b9 5f a1 7b 67 89 30  |.A.....)D._.{g.0|
+00000100  04 b0 90 78 6b 82 fe ae  0c eb e1 5a 64 e2 6f de  |...xk......Zd.o.|
+00000110  de 12 db 4f 1f eb 1d a9  66 a1 62 11 ab 54 1f 5d  |...O....f.b..T.]|
+00000120  c2 ce 1e a8 b3 8b 29 08  76 13 a0 67 5b e6 1b 2c  |......).v..g[..,|
+00000130  bd 1b 42 80 a5 09 b0 03  28 df 77 6f a7 d5 2f 85  |..B.....(.wo../.|
+00000140  2b b1 69 81 5c a0 16 16  1c eb b4 61 f1 f7 70 55  |+.i.\......a..pU|
+00000150  ee 64 9d 8f 1a 0b af af  18 f5 da e6 32 ab b2 28  |.d..........2..(|
+00000160  0d a0 ea b4 44 3d a9 f7  1a 84 c1 8f 30 09 41 13  |....D=......0.A.|
+00000170  a3 34 79 a7 6f da 76 59  62 9f d6 82 0f 48 21 64  |.4y.o.vYb....H!d|
+00000180  11 49 53 cd 3a 44 5a dc  8b 97 8a 84 d2 f9 12 77  |.IS.:DZ........w|
+00000190  b3 5b b0 37 58 7a a3 5a  47 9d c7 e4 83 f5 0a 32  |.[.7Xz.ZG......2|
+000001a0  10 39 aa d6 7c 8e 44 eb  a9 fd 0f c0 6a 80 82 21  |.9..|.D.....j..!|
+000001b0  30 d1 36 31 73 38 c5 bd  16 99 71 b5 49 8e 7f df  |0.61s8....q.I...|
+000001c0  f9 64 7f ff 16 3b 68 7c  b5 7c 1f 41 19 36 dd ef  |.d...;h|.|.A.6..|
+000001d0  65 11 b9 91 c4 d4 40 eb  37 94 69 8b 3b 10 56 45  |e.....@.7.i.;.VE|
+000001e0  ee 56 a8 a7 3d 94 17 5c  fe f2 88 c7 fb 78 8e 51  |.V..=..\.....x.Q|
+000001f0  53 a8 bc b3 88 ee 75 42  1d 41 b8 c5 34 d5 9e bc  |S.....uB.A..4...|
+00000200  b4 b7 1c 97 8b 83 d6 3d  97 4b 43 7a 40 3d 63 6e  |.......=.KCz@=cn|
+00000210  cf 57 9a d3 71 6d 54 fe  38 ec 6f d7 c3 aa 1c a8  |.W..qmT.8.o.....|
+00000220  2b f6 34 96 cb 16 da 3e  2d 74 dd f6 1c 33 3c 4e  |+.4....>-t...3<N|
+00000230  25 d9 e3 c5 85 52 c3 ea  22 ea 86 16 84 31 05 a4  |%....R.."....1..|
+00000240  7d 41 00 bd 4a b3 79 93  18 1c a1 e4 78 1c 90 49  |}A..J.y.....x..I|
+00000250  b4 9f bc d3 2d d0 f9 46  da 13 7c f6 88 5e e1 b2  |....-..F..|..^..|
+00000260  5c 41 12 bf 2f 1f b4 c3  13 8c 2f a6 83 c5 86 ba  |\A../...../.....|
+00000270  20 42 21 57 e1 78 82 0e  4b 55 32 c1 f2 6e 4c a2  | B!W.x..KU2..nL.|
+00000280  a7 c7 63 b3 b5 30 49 9d  7a 51 5e 67 38 52 89 ee  |..c..0I.zQ^g8R..|
+00000290  51 16 34 5c f6 b1 04 30  7b f4 b0 f8 88 6c 9d bc  |Q.4\...0{....l..|
+000002a0  32 5d 8b 73 b0 df f6 a2  dd e7 62 94 d7 b7 68 92  |2].s......b...h.|
+000002b0  d6 a6 6a b2 53 75 d8 a7  43 1f 1e a2 c0 4e 6a 84  |..j.Su..C....Nj.|
+000002c0  e7 6d ae 81 82 dc 43 bd  8c 44 6a db ec 37 34 70  |.m....C..Dj..74p|
+000002d0  a0 e3 39 a1 17 d2 b7 53  bc 06 0e 33 3f 91 b3 a6  |..9....S...3?...|
+000002e0  0a d1 43 b0 94 54 bc b9  07 52 40 6e 49 99 ab 09  |..C..T...R@nI...|
+000002f0  3f dc 5d 5f c9 33 59 03  3f cf 7b 47 54 2d 05 4b  |?.]_.3Y.?.{GT-.K|
+00000300  c2 e6 81 f5 2f 58 5d 84  ad 9d 72 cc 3b 09 70 50  |..../X]...r.;.pP|
+00000310  75 f8 c8 b7 9a 3f b7 3e  aa 6a 75 5d 16 03 03 00  |u....?.>.ju]....|
+00000320  e5 24 71 bf 67 14 d6 5e  2e 0b f5 20 45 e5 51 07  |.$q.g..^... E.Q.|
+00000330  98 f0 75 3c 5c f3 16 88  ba e7 76 fe 10 18 41 38  |..u<\.....v...A8|
+00000340  d5 df 7f 8b d3 2e 1c 0a  4c 83 57 fc e5 63 35 68  |........L.W..c5h|
+00000350  6e 23 5b c3 0c 9d f9 ab  f8 3c 86 b6 ec 54 ec 52  |n#[......<...T.R|
+00000360  a4 45 cf 7b 31 a7 04 ef  5b 0b b1 11 50 8c 95 25  |.E.{1...[...P..%|
+00000370  9a 17 9b 4d 65 9c 0b d3  bb 0d 98 10 d9 34 52 7a  |...Me........4Rz|
+00000380  f8 1e 9e 78 cb 41 27 47  31 cb 25 42 90 e9 3c 02  |...x.A'G1.%B..<.|
+00000390  49 17 01 5f 06 d2 f4 58  35 75 d5 9d 54 65 15 0d  |I.._...X5u..Te..|
+000003a0  02 7e 94 fd c8 ac b8 c4  97 1c 9a 1c 9a 23 d5 d3  |.~...........#..|
+000003b0  44 c6 9a dd f9 b4 d1 48  e9 3d a0 5b d4 66 b3 d9  |D......H.=.[.f..|
+000003c0  11 0c d5 6d 0e 06 9c 00  90 30 d7 97 06 dc 0e e2  |...m.....0......|
+000003d0  59 51 7f b5 2e b8 f7 eb  be 66 56 fa 9d a4 92 db  |YQ.......fV.....|
+000003e0  82 3a d9 fc bd da c5 23  f6 2c 7b 36 2f a8 57 8e  |.:.....#.,{6/.W.|
+000003f0  c6 0a 48 50 e3 f4 e7 07  95 48 9b 45 a9 ba cb e0  |..HP.....H.E....|
+00000400  3e ee 10 f9 0e cc 16 03  03 00 46 24 71 bf 67 14  |>.........F$q.g.|
+00000410  d6 5e 2f 97 87 ae b8 b4  fb f1 67 2b e7 0f f4 be  |.^/.......g+....|
+00000420  24 0a f8 4a c0 42 4b 40  d3 ea e7 e0 f7 2a 9b 80  |$..J.BK@.....*..|
+00000430  bb 62 c0 2d d5 f8 52 19  49 d4 4c 45 1d c2 28 e7  |.b.-..R.I.LE..(.|
+00000440  8f fd b2 47 0e 22 d1 e1  b1 33 c1 26 6a fd 3f 9f  |...G."...3.&j.?.|
+00000450  d8                                                |.|
+>>> Flow 13 (client to server)
+00000000  16 03 03 02 89 00 00 00  00 00 00 00 02 32 20 c7  |.............2 .|
+00000010  66 2d 3f e5 9b f9 e0 1c  7c 1f 3e 21 d9 51 af 9a  |f-?.....|.>!.Q..|
+00000020  60 65 99 c7 3e 0b 48 f2  a3 8f eb ea 75 da af 60  |`e..>.H.....u..`|
+00000030  2e 5b ac 7f 9f d1 1f 69  86 18 49 3b 18 a2 e5 c5  |.[.....i..I;....|
+00000040  d0 c7 fe 3e c6 15 3d 5d  04 4d aa 7e 28 e3 20 d3  |...>..=].M.~(. .|
+00000050  55 c2 ed 4f 61 5f cc f9  39 5f 7d 3a 0f f2 81 5d  |U..Oa_..9_}:...]|
+00000060  fd 4e 86 92 12 cd 2b b7  e6 46 49 b7 b8 5f 8f e5  |.N....+..FI.._..|
+00000070  b7 5e 64 2f 13 33 65 1c  c8 c4 38 bd 70 94 23 e9  |.^d/.3e...8.p.#.|
+00000080  b6 57 81 c8 23 d1 57 85  91 c5 bc 5b 33 55 eb f5  |.W..#.W....[3U..|
+00000090  2d b3 76 53 44 e2 e8 66  fe 42 de f8 6f 03 37 d4  |-.vSD..f.B..o.7.|
+000000a0  a0 a4 75 7a 03 7f 00 92  eb 45 2f b8 5d 01 d3 4b  |..uz.....E/.]..K|
+000000b0  e7 ca 2f 5b 3b 20 67 dc  32 2a 4c 06 1b 03 97 c1  |../[; g.2*L.....|
+000000c0  38 40 35 79 31 25 b0 fe  d8 f3 b7 ee 6c ad 62 3e  |8@5y1%......l.b>|
+000000d0  60 d6 96 6a 10 2b 14 8a  9e 72 f4 c9 63 6a 63 14  |`..j.+...r..cjc.|
+000000e0  d1 b0 e4 1f e9 3d 85 9d  ed 11 3f 85 eb fa ca 46  |.....=....?....F|
+000000f0  17 f8 45 d5 65 28 79 8d  63 8e d7 22 40 9f c7 25  |..E.e(y.c.."@..%|
+00000100  ae e0 72 9f 60 70 95 59  99 25 41 1a e6 e9 45 cb  |..r.`p.Y.%A...E.|
+00000110  3d 5a 2e 2d 4d c2 3c f2  3a 01 61 1f 96 d7 78 1a  |=Z.-M.<.:.a...x.|
+00000120  cd 14 bd 87 75 23 10 7f  67 e4 8e fa 0a 9d 5d e9  |....u#..g.....].|
+00000130  12 f8 c7 35 c1 37 4c a4  91 a1 a5 de 79 9a a7 9c  |...5.7L.....y...|
+00000140  ce d2 c9 72 a8 fa a3 27  24 8d 14 4e d7 11 f3 e9  |...r...'$..N....|
+00000150  07 4d 6d 47 92 4d e2 75  9a 71 d0 1e dd 09 61 0e  |.MmG.M.u.q....a.|
+00000160  16 36 84 3a b1 dd 9b f8  09 dd 73 78 ed f7 29 4e  |.6.:......sx..)N|
+00000170  a6 29 b0 31 54 72 ac 4b  7a 49 13 ba 9b ef b6 8b  |.).1Tr.KzI......|
+00000180  48 dd a1 a7 9d 25 0e b7  37 42 5f 70 27 a7 59 40  |H....%..7B_p'.Y@|
+00000190  fe 72 1a 23 3e 71 b7 56  ef ff 02 c0 c9 07 99 20  |.r.#>q.V....... |
+000001a0  19 d2 9e 65 a5 5e f1 15  d3 ec 6e bb b1 c4 bf c0  |...e.^....n.....|
+000001b0  f8 71 19 bc 77 30 93 72  33 eb 1b c0 62 07 5e ca  |.q..w0.r3...b.^.|
+000001c0  4a bf 89 5d 5d 44 23 fb  58 8e 71 b4 58 41 b9 97  |J..]]D#.X.q.XA..|
+000001d0  8b da b6 a0 b6 40 54 46  01 b9 47 79 21 bc 7c f3  |.....@TF..Gy!.|.|
+000001e0  4c 46 a3 92 ce d6 ec ac  3b 5d 6f 19 65 d1 b0 cd  |LF......;]o.e...|
+000001f0  19 cd 2e 9d 6e 7d d3 57  44 c2 dd c6 56 dd e6 2b  |....n}.WD...V..+|
+00000200  06 c6 f1 46 f1 ba ce e6  d9 c8 1e 03 5d b5 15 37  |...F........]..7|
+00000210  9d 8a d2 01 e7 28 33 30  a2 2b a3 42 d1 05 2f e9  |.....(30.+.B../.|
+00000220  7f 50 bf c8 7f 7b f8 c7  7e 12 3f 97 5e d5 1c 34  |.P...{..~.?.^..4|
+00000230  eb bf 2e c2 f0 6b 36 4e  09 c9 73 0e bb 3a cd f8  |.....k6N..s..:..|
+00000240  5f 2a 13 4d f2 92 b3 ae  4f dd 0e 82 a0 58 a9 be  |_*.M....O....X..|
+00000250  2f c1 20 5c 64 48 11 e3  66 18 22 4d ea aa 76 21  |/. \dH..f."M..v!|
+00000260  07 ac 5a f2 14 38 a7 d8  9a 58 f8 92 62 77 3c 59  |..Z..8...X..bw<Y|
+00000270  1a 31 4e 3f 56 55 2b 9f  87 96 9c 7e c5 f0 10 fa  |.1N?VU+....~....|
+00000280  90 a1 0b 9e e4 66 74 99  80 da 58 85 3d bd 16 03  |.....ft...X.=...|
+00000290  03 00 5e 00 00 00 00 00  00 00 03 42 d9 1d 19 27  |..^........B...'|
+000002a0  98 c0 29 9e bc 35 99 e9  e9 de f5 7c b7 2f ce a1  |..)..5.....|./..|
+000002b0  48 fe a9 79 26 c3 f1 74  63 73 3b 8d b7 4c 47 11  |H..y&..tcs;..LG.|
+000002c0  7c ea 6d 09 4c 1c 10 1d  c9 b4 63 d4 5e c4 f1 34  ||.m.L.....c.^..4|
+000002d0  94 63 1c 04 a1 5f d0 65  7c b6 dd 2b a3 1c 1b 5f  |.c..._.e|..+..._|
+000002e0  5c d6 dc 7f e7 df c4 75  ad df cc ae 71 47 64 cc  |\......u....qGd.|
+000002f0  96 16 03 03 00 a0 00 00  00 00 00 00 00 04 61 37  |..............a7|
+00000300  a3 98 54 d1 7c 5d 14 b9  04 72 6e 02 ab 1a 15 2c  |..T.|]...rn....,|
+00000310  93 07 15 ab 56 b1 ac d5  75 75 2e 25 ae 5e 3f fa  |....V...uu.%.^?.|
+00000320  d0 20 ff 9d e0 ef fd 25  ed 4d 60 56 c7 33 07 d0  |. .....%.M`V.3..|
+00000330  57 09 e4 12 bd aa f0 d2  cc de 0d 45 23 ab b6 67  |W..........E#..g|
+00000340  ea d3 bc e1 4d 3a 75 9f  2d bb 53 b4 70 67 ce 63  |....M:u.-.S.pg.c|
+00000350  83 29 fa 27 2b db ea a3  19 be 79 77 cd 75 fb bf  |.).'+.....yw.u..|
+00000360  c1 27 86 a6 a9 27 06 49  e1 77 13 0d e4 78 0c 07  |.'...'.I.w...x..|
+00000370  d4 1c af 76 f4 7b 05 04  5f 0f ec 66 f9 03 3e 81  |...v.{.._..f..>.|
+00000380  41 be 24 5f 43 2a 99 56  06 a9 d7 be ca 62 46 a2  |A.$_C*.V.....bF.|
+00000390  ba e1 a6 8b 1b 0a 14 03  03 00 19 00 00 00 00 00  |................|
+000003a0  00 00 05 f9 8f d4 80 bf  ed b3 38 3a 12 d9 91 b6  |..........8:....|
+000003b0  cf 87 1a 1b 16 03 03 00  28 00 00 00 00 00 00 00  |........(.......|
+000003c0  00 fb 80 da 9a 59 82 9d  d2 35 57 57 dd 76 a1 b1  |.....Y...5WW.v..|
+000003d0  4a dc a5 cb f6 81 3f e3  4d cc 0e 7f 3a 96 85 f3  |J.....?.M...:...|
+000003e0  ea                                                |.|
+>>> Flow 14 (server to client)
+00000000  14 03 03 00 19 24 71 bf  67 14 d6 5e 30 cc 1c 3f  |.....$q.g..^0..?|
+00000010  3c 20 07 b3 c3 79 d0 6e  fd 59 e6 0d 47 fd 16 03  |< ...y.n.Y..G...|
+00000020  03 00 28 54 db a5 f7 3d  b3 18 49 39 e5 59 93 bb  |..(T...=..I9.Y..|
+00000030  64 93 1c ed 46 d6 f8 89  94 45 ba 4a 9e 73 2e cb  |d...F....E.J.s..|
+00000040  03 18 e4 26 6d 33 e3 34  73 d6 fc 17 03 03 00 21  |...&m3.4s......!|
+00000050  54 db a5 f7 3d b3 18 4a  aa 45 38 3b 50 02 44 37  |T...=..J.E8;P.D7|
+00000060  6a d1 3e f9 d3 3b 33 33  d5 84 2d 52 33 7d 68 84  |j.>..;33..-R3}h.|
+00000070  ef                                                |.|
+>>> Flow 15 (client to server)
+00000000  15 03 03 00 1a 00 00 00  00 00 00 00 01 55 5f 94  |.............U_.|
+00000010  25 d0 89 86 cb 8f 33 6f  b7 b6 35 ec 0f 6a 87     |%.....3o..5..j.|
diff --git a/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateTwiceRejected b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateTwiceRejected
new file mode 100644
index 00000000000..fe2fa88a90e
--- /dev/null
+++ b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiateTwiceRejected
@@ -0,0 +1,255 @@
+>>> Flow 1 (client to server)
+00000000  16 03 01 00 85 01 00 00  81 03 03 00 00 00 00 00  |................|
+00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 22 c0 2f  |............."./|
+00000030  c0 2b c0 30 c0 2c c0 11  c0 07 c0 13 c0 09 c0 14  |.+.0.,..........|
+00000040  c0 0a 00 9c 00 9d 00 05  00 2f 00 35 c0 12 00 0a  |........./.5....|
+00000050  01 00 00 36 00 05 00 05  01 00 00 00 00 00 0a 00  |...6............|
+00000060  08 00 06 00 17 00 18 00  19 00 0b 00 02 01 00 00  |................|
+00000070  0d 00 0e 00 0c 04 01 04  03 05 01 05 03 02 01 02  |................|
+00000080  03 ff 01 00 01 00 00 12  00 00                    |..........|
+>>> Flow 2 (server to client)
+00000000  16 03 03 00 59 02 00 00  55 03 03 51 0e b9 8f 73  |....Y...U..Q...s|
+00000010  ec 20 17 90 80 3a 43 7a  bc 19 19 f5 75 c3 76 a6  |. ...:Cz....u.v.|
+00000020  53 53 4b 77 ce dd ca 4b  1b 1e ed 20 8d e5 a7 6f  |SSKw...K... ...o|
+00000030  53 e9 a4 06 4b 01 a6 08  a1 90 e5 da c9 e3 74 b0  |S...K.........t.|
+00000040  87 1f 17 1a 68 d3 f7 ae  39 b8 3e 80 c0 2f 00 00  |....h...9.>../..|
+00000050  0d ff 01 00 01 00 00 0b  00 04 03 00 01 02 16 03  |................|
+00000060  03 02 71 0b 00 02 6d 00  02 6a 00 02 67 30 82 02  |..q...m..j..g0..|
+00000070  63 30 82 01 cc a0 03 02  01 02 02 09 00 a2 73 00  |c0............s.|
+00000080  0c 81 00 cb f3 30 0d 06  09 2a 86 48 86 f7 0d 01  |.....0...*.H....|
+00000090  01 0b 05 00 30 2b 31 17  30 15 06 03 55 04 0a 13  |....0+1.0...U...|
+000000a0  0e 47 6f 6f 67 6c 65 20  54 45 53 54 49 4e 47 31  |.Google TESTING1|
+000000b0  10 30 0e 06 03 55 04 03  13 07 47 6f 20 52 6f 6f  |.0...U....Go Roo|
+000000c0  74 30 1e 17 0d 31 35 30  31 30 31 30 30 30 30 30  |t0...15010100000|
+000000d0  30 5a 17 0d 32 35 30 31  30 31 30 30 30 30 30 30  |0Z..250101000000|
+000000e0  5a 30 26 31 17 30 15 06  03 55 04 0a 13 0e 47 6f  |Z0&1.0...U....Go|
+000000f0  6f 67 6c 65 20 54 45 53  54 49 4e 47 31 0b 30 09  |ogle TESTING1.0.|
+00000100  06 03 55 04 03 13 02 47  6f 30 81 9f 30 0d 06 09  |..U....Go0..0...|
+00000110  2a 86 48 86 f7 0d 01 01  01 05 00 03 81 8d 00 30  |*.H............0|
+00000120  81 89 02 81 81 00 af 87  88 f6 20 1b 95 65 6c 14  |.......... ..el.|
+00000130  ab 44 05 af 3b 45 14 e3  b7 6d fd 00 63 4d 95 7f  |.D..;E...m..cM..|
+00000140  fe 6a 62 35 86 c0 4a f9  18 7c f6 aa 25 5e 7a 64  |.jb5..J..|..%^zd|
+00000150  31 66 00 ba f4 8e 92 af  c7 6b d8 76 d4 f3 5f 41  |1f.......k.v.._A|
+00000160  cb 6e 56 15 97 1b 97 c1  3c 12 39 21 66 3d 2b 16  |.nV.....<.9!f=+.|
+00000170  d1 bc db 1c c0 a7 da b7  ca ad ba da cb d5 21 50  |..............!P|
+00000180  ec de 8d ab d1 6b 81 4b  89 02 f3 c4 be c1 6c 89  |.....k.K......l.|
+00000190  b1 44 84 bd 21 d1 04 7d  9d 16 4d f9 82 15 f6 ef  |.D..!..}..M.....|
+000001a0  fa d6 09 47 f2 fb 02 03  01 00 01 a3 81 93 30 81  |...G..........0.|
+000001b0  90 30 0e 06 03 55 1d 0f  01 01 ff 04 04 03 02 05  |.0...U..........|
+000001c0  a0 30 1d 06 03 55 1d 25  04 16 30 14 06 08 2b 06  |.0...U.%..0...+.|
+000001d0  01 05 05 07 03 01 06 08  2b 06 01 05 05 07 03 02  |........+.......|
+000001e0  30 0c 06 03 55 1d 13 01  01 ff 04 02 30 00 30 19  |0...U.......0.0.|
+000001f0  06 03 55 1d 0e 04 12 04  10 12 50 8d 89 6f 1b d1  |..U.......P..o..|
+00000200  dc 54 4d 6e cb 69 5e 06  f4 30 1b 06 03 55 1d 23  |.TMn.i^..0...U.#|
+00000210  04 14 30 12 80 10 bf 3d  b6 a9 66 f2 b8 40 cf ea  |..0....=..f..@..|
+00000220  b4 03 78 48 1a 41 30 19  06 03 55 1d 11 04 12 30  |..xH.A0...U....0|
+00000230  10 82 0e 65 78 61 6d 70  6c 65 2e 67 6f 6c 61 6e  |...example.golan|
+00000240  67 30 0d 06 09 2a 86 48  86 f7 0d 01 01 0b 05 00  |g0...*.H........|
+00000250  03 81 81 00 92 7c af 91  55 12 18 96 59 31 a6 48  |.....|..U...Y1.H|
+00000260  40 d5 2d d5 ee bb 02 a0  f5 c2 1e 7c 9b b3 30 7d  |@.-........|..0}|
+00000270  3c dc 76 da 4f 3d c0 fa  ae 2d 33 24 6b 03 7b 1b  |<.v.O=...-3$k.{.|
+00000280  67 59 11 21 b5 11 bc 77  b9 d9 e0 6e a8 2d 2e 35  |gY.!...w...n.-.5|
+00000290  fa 64 5f 22 3e 63 10 6b  be ff 14 86 6d 0d f0 15  |.d_">c.k....m...|
+000002a0  31 a8 14 38 1e 3b 84 87  2c cb 98 ed 51 76 b9 b1  |1..8.;..,...Qv..|
+000002b0  4f dd db 9b 84 04 86 40  fa 51 dd ba b4 8d eb e3  |O......@.Q......|
+000002c0  46 de 46 b9 4f 86 c7 f9  a4 c2 41 34 ac cc f6 ea  |F.F.O.....A4....|
+000002d0  b0 ab 39 18 16 03 03 00  cd 0c 00 00 c9 03 00 17  |..9.............|
+000002e0  41 04 5e 2e 43 b7 c2 0f  e8 4a 33 aa b8 d6 04 7f  |A.^.C....J3.....|
+000002f0  2b be a2 e3 6f fa 05 1a  d1 64 a7 d1 ec 45 f9 16  |+...o....d...E..|
+00000300  b7 75 ad f2 52 3e a3 60  67 f8 fb 87 a0 c0 d4 2f  |.u..R>.`g....../|
+00000310  f4 66 c9 dd 38 40 79 5b  16 75 0b 16 6a d8 e5 ad  |.f..8@y[.u..j...|
+00000320  63 f3 04 01 00 80 5e 89  b3 6b f4 a1 35 b3 27 be  |c.....^..k..5.'.|
+00000330  6a d4 39 42 7c ac e2 d4  9f a0 a0 a3 95 22 b5 09  |j.9B|........"..|
+00000340  70 4a 0c 6f cf 7f 69 f9  7d 27 c4 0d e7 b8 9c 82  |pJ.o..i.}'......|
+00000350  c9 0d 1d bb 5c 23 20 eb  ca 09 ca 02 a0 56 27 10  |....\# ......V'.|
+00000360  c5 d6 13 7d cd 05 64 cc  53 20 5d df ac 00 90 7f  |...}..d.S ].....|
+00000370  d7 cd f2 a1 07 9c 06 c2  e6 d1 94 60 d3 c6 97 a6  |...........`....|
+00000380  3c e5 89 67 e7 cc b7 c1  ba 75 dc 17 2b 47 ce 23  |<..g.....u..+G.#|
+00000390  a3 37 3b 3f 32 39 ae 4a  64 17 d2 64 d1 75 23 8a  |.7;?29.Jd..d.u#.|
+000003a0  e3 b4 fa 75 17 72 16 03  03 00 04 0e 00 00 00     |...u.r.........|
+>>> Flow 3 (client to server)
+00000000  16 03 03 00 46 10 00 00  42 41 04 1e 18 37 ef 0d  |....F...BA...7..|
+00000010  19 51 88 35 75 71 b5 e5  54 5b 12 2e 8f 09 67 fd  |.Q.5uq..T[....g.|
+00000020  a7 24 20 3e b2 56 1c ce  97 28 5e f8 2b 2d 4f 9e  |.$ >.V...(^.+-O.|
+00000030  f1 07 9f 6c 4b 5b 83 56  e2 32 42 e9 58 b6 d7 49  |...lK[.V.2B.X..I|
+00000040  a6 b5 68 1a 41 03 56 6b  dc 5a 89 14 03 03 00 01  |..h.A.Vk.Z......|
+00000050  01 16 03 03 00 28 00 00  00 00 00 00 00 00 4f ef  |.....(........O.|
+00000060  08 7c a7 de 53 70 7e 78  fb 08 79 97 1f bd 33 92  |.|..Sp~x..y...3.|
+00000070  c5 46 4d 64 32 bb 94 f0  07 ad 7d 00 86 9e        |.FMd2.....}...|
+>>> Flow 4 (server to client)
+00000000  14 03 03 00 01 01 16 03  03 00 28 59 c3 19 1f ed  |..........(Y....|
+00000010  d1 1b 54 5b 66 81 47 29  9a 77 84 87 a0 bd c5 d4  |..T[f.G).w......|
+00000020  f0 4e e2 11 d3 1d 26 dd  87 7a 55 11 48 37 7f 3a  |.N....&..zU.H7.:|
+00000030  2c fc 62                                          |,.b|
+>>> Flow 5 (client to server)
+00000000  17 03 03 00 1e 00 00 00  00 00 00 00 01 02 12 57  |...............W|
+00000010  9d 64 c5 47 13 95 13 7b  2b 3e e0 f7 ae 49 0f c7  |.d.G...{+>...I..|
+00000020  0e 3a 67                                          |.:g|
+>>> Flow 6 (server to client)
+00000000  16 03 03 00 1c 59 c3 19  1f ed d1 1b 55 ac 23 dc  |.....Y......U.#.|
+00000010  0c 35 65 1e 7a 65 4f 47  13 46 a0 d0 d0 4d 0a 1f  |.5e.zeOG.F...M..|
+00000020  5c                                                |\|
+>>> Flow 7 (client to server)
+00000000  16 03 03 00 a9 00 00 00  00 00 00 00 02 c0 05 0c  |................|
+00000010  76 0a 46 19 16 17 a6 75  af 11 bb 73 37 74 a4 26  |v.F....u...s7t.&|
+00000020  d9 16 93 b8 19 5e 2f 17  52 d1 12 9e 36 90 4e c9  |.....^/.R...6.N.|
+00000030  7a f9 89 75 3b d9 d4 e1  2e cf a0 5d 03 7d cc f6  |z..u;......].}..|
+00000040  73 aa a9 52 c7 65 78 d0  89 6f b1 15 6e f9 9e 55  |s..R.ex..o..n..U|
+00000050  42 9e 22 09 df 97 00 31  b8 73 57 1b 93 ff 0c e7  |B."....1.sW.....|
+00000060  46 29 40 79 a7 c0 de b9  44 93 7b 4d 35 a0 35 65  |F)@y....D.{M5.5e|
+00000070  6e 58 07 90 2b 11 49 26  10 f7 c7 32 f7 8e 6e a7  |nX..+.I&...2..n.|
+00000080  9b 75 ba cb 4a ce f7 f0  f1 31 ca 04 a6 02 d0 62  |.u..J....1.....b|
+00000090  da 9b 8b 27 8e 04 b8 4a  49 0d d6 31 10 93 30 37  |...'...JI..1..07|
+000000a0  ad ea d7 c4 49 98 90 f3  a1 45 f4 69 2e 59        |....I....E.i.Y|
+>>> Flow 8 (server to client)
+00000000  16 03 03 00 89 59 c3 19  1f ed d1 1b 56 c8 38 86  |.....Y......V.8.|
+00000010  22 b6 5f 55 cb 0c e1 40  e6 12 f2 71 d5 09 bc 47  |"._U...@...q...G|
+00000020  ea 83 38 3a 58 f4 34 da  ae 7f 64 fb 8c bc 71 64  |..8:X.4...d...qd|
+00000030  1b aa 84 e4 3e c1 cc c4  a9 05 36 13 5a 9b 1e c0  |....>.....6.Z...|
+00000040  44 cc 86 54 f0 75 b7 d0  aa b0 f0 3a b5 c7 f1 cc  |D..T.u.....:....|
+00000050  1f cd 8e 9e 9e bb 24 23  c3 05 0b a5 1d f3 0b 41  |......$#.......A|
+00000060  41 19 89 1e ee 51 fc b3  e8 e2 6e a8 3f c4 8b ab  |A....Q....n.?...|
+00000070  cb af d9 a1 7e 1c db e7  6c f6 23 71 c6 31 db 40  |....~...l.#q.1.@|
+00000080  a8 a7 08 fb 1a ff 8d 94  53 88 9a 11 73 6a 16 03  |........S...sj..|
+00000090  03 02 89 59 c3 19 1f ed  d1 1b 57 17 dd 9c b5 a5  |...Y......W.....|
+000000a0  89 12 3a 14 61 34 e0 1d  0b 35 d6 3a 6c 09 93 2b  |..:.a4...5.:l..+|
+000000b0  6c 69 ee f4 f3 be fb 42  33 99 fd 9a e6 21 38 68  |li.....B3....!8h|
+000000c0  a6 19 37 43 24 81 ba 35  12 fe ab ed 49 0b 03 54  |..7C$..5....I..T|
+000000d0  11 a7 74 4d bb ba e7 b9  f3 ee 6a 4e 1a 84 2f 03  |..tM......jN../.|
+000000e0  0c d1 28 21 49 84 f4 3c  5b 15 92 07 5c 6a 24 89  |..(!I..<[...\j$.|
+000000f0  00 cf 78 31 76 23 0f 9d  45 3b 93 a5 68 ee 9c 73  |..x1v#..E;..h..s|
+00000100  14 3f 08 30 37 40 4e 8b  a4 02 03 3c 4b 52 74 99  |.?.07@N....<KRt.|
+00000110  0e 9a ec 40 c6 74 16 ef  c5 48 68 33 86 d7 06 57  |...@.t...Hh3...W|
+00000120  bf 8a 6f 3f 41 fe 4d f2  37 0a 1b fd fb 66 55 bd  |..o?A.M.7....fU.|
+00000130  70 4d b0 8c 4f 78 24 eb  1f 8f 22 c7 aa 07 89 04  |pM..Ox$...".....|
+00000140  6a b3 07 15 37 25 21 63  97 39 b1 c1 9b fa 81 5e  |j...7%!c.9.....^|
+00000150  69 c9 c7 4a 9c 5d b3 6a  41 d0 5e b9 f4 d5 5c a1  |i..J.].jA.^...\.|
+00000160  8e 8a ad 58 6e 5c 4f 73  62 38 1c 5f 8d b1 67 63  |...Xn\Osb8._..gc|
+00000170  49 da 4b 4e 83 54 34 8f  8d 12 de 4e 43 4d dc b9  |I.KN.T4....NCM..|
+00000180  02 ab 08 59 db 0b 45 7e  f5 b8 e2 33 f1 04 de 16  |...Y..E~...3....|
+00000190  05 bf b4 2b 07 a1 11 e4  9e 48 f7 52 ab 20 89 04  |...+.....H.R. ..|
+000001a0  a7 44 28 7a 12 6c 19 ab  2f 68 1a d9 26 ec 72 a0  |.D(z.l../h..&.r.|
+000001b0  62 83 48 6f 4b 70 7d 74  3a 43 4f a6 38 37 fe 59  |b.HoKp}t:CO.87.Y|
+000001c0  6e 72 5d 81 7d 2c c7 e1  6b 06 47 41 56 17 2c 25  |nr].},..k.GAV.,%|
+000001d0  06 b1 7f f5 10 0a 31 a3  12 b1 5c 01 2f e0 a6 e4  |......1...\./...|
+000001e0  fa ab d2 0b 02 77 ad ac  f8 54 db 70 20 0a 1f 04  |.....w...T.p ...|
+000001f0  86 a8 32 05 26 ee 7d e0  e9 03 19 cc 8f 67 f5 b6  |..2.&.}......g..|
+00000200  97 fe 06 5e c1 d5 df 25  f5 39 70 64 57 a8 c9 84  |...^...%.9pdW...|
+00000210  8f 0f 25 f8 c8 f9 17 70  e5 00 3c 4a 9f 4b c1 d9  |..%....p..<J.K..|
+00000220  6e b8 1a e4 6d 85 a4 e2  42 44 71 ba 43 9b 03 70  |n...m...BDq.C..p|
+00000230  14 ff 72 5e 5c 69 24 2e  52 0c 73 8b df 50 99 68  |..r^\i$.R.s..P.h|
+00000240  57 81 c1 ed b6 33 fc 74  15 45 fd a2 c4 8c f8 95  |W....3.t.E......|
+00000250  bf 8d 0e 92 91 42 72 77  03 ec c6 f6 9a 02 ca 7d  |.....Brw.......}|
+00000260  3c 87 72 eb 8d 30 3a 5c  b4 03 4a 6d 2e 83 22 c5  |<.r..0:\..Jm..".|
+00000270  e2 4a 95 83 7a 72 72 f2  2a 11 25 4a bd 04 16 ab  |.J..zrr.*.%J....|
+00000280  6a 48 44 2b 99 fb 6f 61  9a 14 4a 42 1e bf d1 82  |jHD+..oa..JB....|
+00000290  db 62 5f ac 1e 6d 1d 1b  0d 4b 9d 8d 3a 84 94 b4  |.b_..m...K..:...|
+000002a0  aa 08 5b 90 7f d2 46 b0  a7 40 f4 55 76 6b 0d 4c  |..[...F..@.Uvk.L|
+000002b0  8e e3 8c fd ed 33 7d 93  f8 d8 c3 db 26 2d db a1  |.....3}.....&-..|
+000002c0  24 bc b0 fb 26 5f ec 13  5f 97 05 bb 5c 3c cc a3  |$...&_.._...\<..|
+000002d0  c2 57 58 cd 2e 70 0c a7  77 c5 e5 e8 0c 42 f2 e0  |.WX..p..w....B..|
+000002e0  1c 11 0f 62 4b 84 49 c2  b7 10 83 2e 16 1c 38 d4  |...bK.I.......8.|
+000002f0  10 f7 ca 71 7a 87 c5 a3  66 d2 98 1e c8 f2 c0 37  |...qz...f......7|
+00000300  0e 28 31 fe 8e 3e f4 03  74 6e 91 42 22 cb 5d 7f  |.(1..>..tn.B".].|
+00000310  d2 22 da 3c f2 a0 2d 09  a9 a5 2d 14 16 03 03 00  |.".<..-...-.....|
+00000320  e5 59 c3 19 1f ed d1 1b  58 3f 19 93 55 cb 19 f8  |.Y......X?..U...|
+00000330  02 1a 43 b3 b2 6c 4e 3e  ee 99 b3 df fd 45 24 ac  |..C..lN>.....E$.|
+00000340  63 e7 45 cc a4 44 ca cf  3a e1 81 88 01 9a b3 64  |c.E..D..:......d|
+00000350  fe 6b 36 57 9f 81 fc 40  8d ef 21 af 00 be 43 f7  |.k6W...@..!...C.|
+00000360  a3 3b a3 fa f0 01 f2 b4  ab 8a d1 a8 14 58 1b 6f  |.;...........X.o|
+00000370  75 01 35 92 54 a7 a6 c1  99 1e 92 d8 87 53 7b 42  |u.5.T........S{B|
+00000380  4a 76 96 5e e9 db bb 4e  f1 d9 bb e6 d2 b0 34 10  |Jv.^...N......4.|
+00000390  1b 4c d5 2c ca af 19 0d  3e 77 ee 77 0e 5f ff e2  |.L.,....>w.w._..|
+000003a0  02 c5 4a f2 ec 0b 7d cf  d1 e7 3c 72 d2 17 4d 6c  |..J...}...<r..Ml|
+000003b0  a7 ca 3a 1b 00 2b 69 17  e5 a9 82 69 49 c2 ff 8a  |..:..+i....iI...|
+000003c0  f1 e8 ab 1b c3 8d da f1  31 ba a6 f4 7c 3c 01 6f  |........1...|<.o|
+000003d0  ed a8 6f e2 4f a3 68 77  b7 54 b5 87 1b 5c 5c fb  |..o.O.hw.T...\\.|
+000003e0  83 bf 48 4d 36 43 d6 f7  0a 48 74 f3 44 9d 43 53  |..HM6C...Ht.D.CS|
+000003f0  f8 54 1b 57 97 24 53 5a  93 e2 e9 33 f0 35 5f 0a  |.T.W.$SZ...3.5_.|
+00000400  0d 4c ce 92 4d c9 16 03  03 00 46 59 c3 19 1f ed  |.L..M.....FY....|
+00000410  d1 1b 59 80 50 fc 3a 56  e0 0b 06 b4 58 39 0c d8  |..Y.P.:V....X9..|
+00000420  4b b1 11 7a bd cf 1c 78  41 62 ee 22 74 61 7d 61  |K..z...xAb."ta}a|
+00000430  91 3d 0a 74 a4 b0 cd 25  70 19 a5 de d8 1b df 12  |.=.t...%p.......|
+00000440  4e b8 71 db ac bc 48 ea  89 32 ec 27 69 02 0d 8b  |N.q...H..2.'i...|
+00000450  83                                                |.|
+>>> Flow 9 (client to server)
+00000000  16 03 03 02 89 00 00 00  00 00 00 00 03 be 8d 55  |...............U|
+00000010  8a 5b 24 10 db e3 f2 11  28 0d 26 cc 1b bc 38 fa  |.[$.....(.&...8.|
+00000020  1c 8c f8 c9 64 55 ec 43  16 f7 ca af 12 a8 1c 09  |....dU.C........|
+00000030  0d b0 47 bc 9f 19 02 91  ab 9d 33 b4 bc 45 f7 4d  |..G.......3..E.M|
+00000040  53 85 4a 91 7e d3 2d dc  d6 02 6e 4a 34 51 99 db  |S.J.~.-...nJ4Q..|
+00000050  f2 a1 8d 34 60 6f 15 6a  f9 4d 7a 03 0b dc f7 c1  |...4`o.j.Mz.....|
+00000060  99 c2 2c b8 4c a1 63 ce  a2 fb 33 0d d6 dd d4 0a  |..,.L.c...3.....|
+00000070  88 0c 1d 5c ea 06 00 33  3a 06 6e 3d 63 b4 d5 0c  |...\...3:.n=c...|
+00000080  9b 69 f0 86 72 db 47 52  3d 61 0b 66 57 8d 7b 67  |.i..r.GR=a.fW.{g|
+00000090  1e 42 aa b8 ca e6 d3 07  56 cf f5 09 14 25 a2 1d  |.B......V....%..|
+000000a0  3b 3e dd 0c 41 ac 66 05  3b db 59 85 9d e2 9f 8b  |;>..A.f.;.Y.....|
+000000b0  21 c0 9a 3b 0b 8e 5b 4b  af ac 73 87 d3 b4 34 b7  |!..;..[K..s...4.|
+000000c0  2e 26 b0 5d 10 3a 2e 00  cc ac 40 b5 72 40 69 fa  |.&.].:....@.r@i.|
+000000d0  11 04 b6 37 38 84 59 76  29 08 f0 0f 0f 79 40 7c  |...78.Yv)....y@||
+000000e0  e4 08 15 b7 58 cd 6c f4  d6 77 d6 f8 cb 1d ca 5c  |....X.l..w.....\|
+000000f0  41 d7 f8 64 63 14 a5 a5  3a 13 ce 55 b4 0a d9 b5  |A..dc...:..U....|
+00000100  34 f9 5e 69 f2 9a 62 88  b9 69 2f 93 08 2c 55 c4  |4.^i..b..i/..,U.|
+00000110  5d 0d cb 92 ac 2c 30 27  83 11 68 9f 74 35 5d 3a  |]....,0'..h.t5]:|
+00000120  96 4c 57 91 95 a8 e7 03  fa b7 ae 8b 94 e3 39 38  |.LW...........98|
+00000130  6d e1 ad b1 f7 26 2c 90  d4 3c eb a5 5e df e4 29  |m....&,..<..^..)|
+00000140  39 ff ba d2 04 f4 b4 9c  fa c2 da 34 bc 04 32 07  |9..........4..2.|
+00000150  db 52 38 fd 92 89 4c e9  50 13 e5 90 e7 f1 88 5e  |.R8...L.P......^|
+00000160  c1 7a 9b fa 6e 1f 99 ce  52 77 0c 03 d8 a6 5d 64  |.z..n...Rw....]d|
+00000170  ab 58 82 93 10 a1 4f 35  ea a3 6d af a9 64 17 3d  |.X....O5..m..d.=|
+00000180  fc a8 d8 9e 7e d7 44 af  2a c1 d6 a8 4d 78 b3 0b  |....~.D.*...Mx..|
+00000190  d1 0b 3d 54 e2 c8 df 84  61 cb 92 1a d8 ce 23 a3  |..=T....a.....#.|
+000001a0  68 f7 af 40 53 09 f0 cc  00 7d 39 83 2c 6d f4 44  |h..@S....}9.,m.D|
+000001b0  d6 95 59 06 0a ef 9c 74  39 b3 70 cb 0a 0c 13 cd  |..Y....t9.p.....|
+000001c0  ec 1f bf 75 93 01 1a 35  68 75 8b 80 15 80 7d a9  |...u...5hu....}.|
+000001d0  d0 25 9a 52 bc 02 bf 71  eb 60 76 2a 74 90 c8 16  |.%.R...q.`v*t...|
+000001e0  80 03 c2 a8 0c be 94 7c  12 b0 ee 45 3a 38 09 5a  |.......|...E:8.Z|
+000001f0  bf 8b ca 78 f3 9e 79 8a  9f 65 57 84 f8 33 79 2a  |...x..y..eW..3y*|
+00000200  f8 8c e0 c8 4b 9e 12 19  b1 3f ba cf 9d db 48 13  |....K....?....H.|
+00000210  b4 b0 53 0e 7a 6b 1d 21  13 45 37 8d 90 75 88 f9  |..S.zk.!.E7..u..|
+00000220  b5 9d 41 d0 ee 95 5f 6a  e5 96 b6 48 ce 3b 43 20  |..A..._j...H.;C |
+00000230  47 15 db eb ba af 6d bf  38 26 e7 ad 86 ba 1e 91  |G.....m.8&......|
+00000240  be 8b df ba 5c 30 6e 3c  13 6a 96 68 13 24 bf 06  |....\0n<.j.h.$..|
+00000250  f1 d2 b0 05 8f 8e 21 7f  6a 09 5f b8 be 0b c5 5f  |......!.j._...._|
+00000260  67 60 94 ec 78 65 6f 70  94 9b 15 82 07 f4 88 fb  |g`..xeop........|
+00000270  a2 94 68 f7 57 0a 9c ec  ab 3f 8f d5 83 ec 6a 24  |..h.W....?....j$|
+00000280  6f 88 4f 22 7f a1 82 cb  ef ec 4c 33 b9 c1 16 03  |o.O"......L3....|
+00000290  03 00 5e 00 00 00 00 00  00 00 04 34 f9 69 a5 83  |..^........4.i..|
+000002a0  c5 86 34 51 f0 07 5b 44  51 36 c1 0d f7 71 c7 1b  |..4Q..[DQ6...q..|
+000002b0  70 27 aa 35 cd c7 10 76  fd 96 27 dc bc 6f 39 ff  |p'.5...v..'..o9.|
+000002c0  f1 a7 de e3 c5 21 70 e9  70 b1 52 d2 f0 be c0 72  |.....!p.p.R....r|
+000002d0  e5 aa 2b 1a 1d a8 8f 10  37 b5 2f c7 b9 32 c8 3c  |..+.....7./..2.<|
+000002e0  7c c8 11 a5 dc aa 84 12  57 f1 ff 3b f9 04 a4 29  ||.......W..;...)|
+000002f0  24 16 03 03 00 a0 00 00  00 00 00 00 00 05 1a 86  |$...............|
+00000300  c7 35 6f 23 c5 38 85 85  0e 31 df 33 1a 42 6e f8  |.5o#.8...1.3.Bn.|
+00000310  c3 f7 81 29 aa 03 85 8c  5a 8a e1 9b 1c d3 6f 7d  |...)....Z.....o}|
+00000320  36 41 45 30 06 2b dd 19  dc 22 9e 9e d4 bc 0e 51  |6AE0.+...".....Q|
+00000330  65 59 e9 7e 1b a1 d1 54  4b 3c 9a 41 de b9 43 98  |eY.~...TK<.A..C.|
+00000340  a5 ef 7a b8 77 69 f7 a5  80 02 d6 46 73 96 89 46  |..z.wi.....Fs..F|
+00000350  43 3a d7 ae 21 64 db 05  b5 7d fc 83 a3 75 ba ad  |C:..!d...}...u..|
+00000360  0d d2 d6 9b 51 3b cb 37  85 46 92 b5 57 eb 2c dc  |....Q;.7.F..W.,.|
+00000370  b2 8f e2 c0 7f 29 bf 5e  bd f0 26 dd 31 e4 31 af  |.....).^..&.1.1.|
+00000380  09 51 e4 26 09 56 a2 f4  5d fc c5 cb c8 da 51 ee  |.Q.&.V..].....Q.|
+00000390  35 2e bb 3e ee bb 14 03  03 00 19 00 00 00 00 00  |5..>............|
+000003a0  00 00 06 b5 3d 07 af c9  3f ad f0 25 b4 5e b9 0f  |....=...?..%.^..|
+000003b0  fa f0 16 48 16 03 03 00  28 00 00 00 00 00 00 00  |...H....(.......|
+000003c0  00 43 54 67 b4 f1 0e 1d  9d 7f ab f7 4c b6 77 3f  |.CTg........L.w?|
+000003d0  d0 17 da 6a 61 75 a8 c8  42 47 fb 2a f7 22 85 02  |...jau..BG.*."..|
+000003e0  b0                                                |.|
+>>> Flow 10 (server to client)
+00000000  14 03 03 00 19 59 c3 19  1f ed d1 1b 5a 9d 51 67  |.....Y......Z.Qg|
+00000010  ff ed 61 fd 01 85 c2 46  f1 26 e1 08 c3 5b 16 03  |..a....F.&...[..|
+00000020  03 00 28 02 08 83 98 20  78 eb a5 8e f5 d3 31 b6  |..(.... x.....1.|
+00000030  6d 4b 3a 9c cd 76 30 ca  92 4b 6c 17 2c d8 c5 d5  |mK:..v0..Kl.,...|
+00000040  7d 59 76 f8 ff 0c 8f f4  f6 fb 81 17 03 03 00 21  |}Yv............!|
+00000050  02 08 83 98 20 78 eb a6  9b c6 07 33 3b 43 e4 5b  |.... x.....3;C.[|
+00000060  c6 d4 31 6e 2b 5b 4a 65  c2 0a df 27 02 a2 3e 3b  |..1n+[Je...'..>;|
+00000070  04 16 03 03 00 1c 02 08  83 98 20 78 eb a7 43 45  |.......... x..CE|
+00000080  df 9b 74 94 81 17 21 b1  7d d5 c0 7a 2b cc 38 a1  |..t...!.}..z+.8.|
+00000090  30 1d                                             |0.|
+>>> Flow 11 (client to server)
+00000000  15 03 03 00 1a 00 00 00  00 00 00 00 01 d6 2b 5a  |..............+Z|
+00000010  7d c9 ba d3 94 cc 45 26  1c 1e 1e 70 39 6c 4e 15  |}.....E&...p9lN.|
+00000020  03 03 00 1a 00 00 00 00  00 00 00 02 fd 76 21 e8  |.............v!.|
+00000030  b5 16 14 43 36 9f 61 14  6d 40 76 e3 14 11        |...C6.a.m@v...|
diff --git a/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiationRejected b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiationRejected
new file mode 100644
index 00000000000..90adc18fe92
--- /dev/null
+++ b/libgo/go/crypto/tls/testdata/Client-TLSv12-RenegotiationRejected
@@ -0,0 +1,97 @@
+>>> Flow 1 (client to server)
+00000000  16 03 01 00 85 01 00 00  81 03 03 00 00 00 00 00  |................|
+00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 22 c0 2f  |............."./|
+00000030  c0 2b c0 30 c0 2c c0 11  c0 07 c0 13 c0 09 c0 14  |.+.0.,..........|
+00000040  c0 0a 00 9c 00 9d 00 05  00 2f 00 35 c0 12 00 0a  |........./.5....|
+00000050  01 00 00 36 00 05 00 05  01 00 00 00 00 00 0a 00  |...6............|
+00000060  08 00 06 00 17 00 18 00  19 00 0b 00 02 01 00 00  |................|
+00000070  0d 00 0e 00 0c 04 01 04  03 05 01 05 03 02 01 02  |................|
+00000080  03 ff 01 00 01 00 00 12  00 00                    |..........|
+>>> Flow 2 (server to client)
+00000000  16 03 03 00 59 02 00 00  55 03 03 b1 7d c5 82 a4  |....Y...U...}...|
+00000010  f7 1d 3a b9 c0 da 13 7c  2f 75 22 a4 5f 2e 58 2a  |..:....|/u"._.X*|
+00000020  39 eb 18 7c bb 0d 98 ba  51 2e 4a 20 41 40 2f 53  |9..|....Q.J A@/S|
+00000030  bc 16 e0 a4 44 07 f0 5e  8f 43 a3 69 87 0b 94 dd  |....D..^.C.i....|
+00000040  60 a0 20 d0 25 e1 a1 a0  b8 0d d8 00 c0 2f 00 00  |`. .%......../..|
+00000050  0d ff 01 00 01 00 00 0b  00 04 03 00 01 02 16 03  |................|
+00000060  03 02 71 0b 00 02 6d 00  02 6a 00 02 67 30 82 02  |..q...m..j..g0..|
+00000070  63 30 82 01 cc a0 03 02  01 02 02 09 00 a2 73 00  |c0............s.|
+00000080  0c 81 00 cb f3 30 0d 06  09 2a 86 48 86 f7 0d 01  |.....0...*.H....|
+00000090  01 0b 05 00 30 2b 31 17  30 15 06 03 55 04 0a 13  |....0+1.0...U...|
+000000a0  0e 47 6f 6f 67 6c 65 20  54 45 53 54 49 4e 47 31  |.Google TESTING1|
+000000b0  10 30 0e 06 03 55 04 03  13 07 47 6f 20 52 6f 6f  |.0...U....Go Roo|
+000000c0  74 30 1e 17 0d 31 35 30  31 30 31 30 30 30 30 30  |t0...15010100000|
+000000d0  30 5a 17 0d 32 35 30 31  30 31 30 30 30 30 30 30  |0Z..250101000000|
+000000e0  5a 30 26 31 17 30 15 06  03 55 04 0a 13 0e 47 6f  |Z0&1.0...U....Go|
+000000f0  6f 67 6c 65 20 54 45 53  54 49 4e 47 31 0b 30 09  |ogle TESTING1.0.|
+00000100  06 03 55 04 03 13 02 47  6f 30 81 9f 30 0d 06 09  |..U....Go0..0...|
+00000110  2a 86 48 86 f7 0d 01 01  01 05 00 03 81 8d 00 30  |*.H............0|
+00000120  81 89 02 81 81 00 af 87  88 f6 20 1b 95 65 6c 14  |.......... ..el.|
+00000130  ab 44 05 af 3b 45 14 e3  b7 6d fd 00 63 4d 95 7f  |.D..;E...m..cM..|
+00000140  fe 6a 62 35 86 c0 4a f9  18 7c f6 aa 25 5e 7a 64  |.jb5..J..|..%^zd|
+00000150  31 66 00 ba f4 8e 92 af  c7 6b d8 76 d4 f3 5f 41  |1f.......k.v.._A|
+00000160  cb 6e 56 15 97 1b 97 c1  3c 12 39 21 66 3d 2b 16  |.nV.....<.9!f=+.|
+00000170  d1 bc db 1c c0 a7 da b7  ca ad ba da cb d5 21 50  |..............!P|
+00000180  ec de 8d ab d1 6b 81 4b  89 02 f3 c4 be c1 6c 89  |.....k.K......l.|
+00000190  b1 44 84 bd 21 d1 04 7d  9d 16 4d f9 82 15 f6 ef  |.D..!..}..M.....|
+000001a0  fa d6 09 47 f2 fb 02 03  01 00 01 a3 81 93 30 81  |...G..........0.|
+000001b0  90 30 0e 06 03 55 1d 0f  01 01 ff 04 04 03 02 05  |.0...U..........|
+000001c0  a0 30 1d 06 03 55 1d 25  04 16 30 14 06 08 2b 06  |.0...U.%..0...+.|
+000001d0  01 05 05 07 03 01 06 08  2b 06 01 05 05 07 03 02  |........+.......|
+000001e0  30 0c 06 03 55 1d 13 01  01 ff 04 02 30 00 30 19  |0...U.......0.0.|
+000001f0  06 03 55 1d 0e 04 12 04  10 12 50 8d 89 6f 1b d1  |..U.......P..o..|
+00000200  dc 54 4d 6e cb 69 5e 06  f4 30 1b 06 03 55 1d 23  |.TMn.i^..0...U.#|
+00000210  04 14 30 12 80 10 bf 3d  b6 a9 66 f2 b8 40 cf ea  |..0....=..f..@..|
+00000220  b4 03 78 48 1a 41 30 19  06 03 55 1d 11 04 12 30  |..xH.A0...U....0|
+00000230  10 82 0e 65 78 61 6d 70  6c 65 2e 67 6f 6c 61 6e  |...example.golan|
+00000240  67 30 0d 06 09 2a 86 48  86 f7 0d 01 01 0b 05 00  |g0...*.H........|
+00000250  03 81 81 00 92 7c af 91  55 12 18 96 59 31 a6 48  |.....|..U...Y1.H|
+00000260  40 d5 2d d5 ee bb 02 a0  f5 c2 1e 7c 9b b3 30 7d  |@.-........|..0}|
+00000270  3c dc 76 da 4f 3d c0 fa  ae 2d 33 24 6b 03 7b 1b  |<.v.O=...-3$k.{.|
+00000280  67 59 11 21 b5 11 bc 77  b9 d9 e0 6e a8 2d 2e 35  |gY.!...w...n.-.5|
+00000290  fa 64 5f 22 3e 63 10 6b  be ff 14 86 6d 0d f0 15  |.d_">c.k....m...|
+000002a0  31 a8 14 38 1e 3b 84 87  2c cb 98 ed 51 76 b9 b1  |1..8.;..,...Qv..|
+000002b0  4f dd db 9b 84 04 86 40  fa 51 dd ba b4 8d eb e3  |O......@.Q......|
+000002c0  46 de 46 b9 4f 86 c7 f9  a4 c2 41 34 ac cc f6 ea  |F.F.O.....A4....|
+000002d0  b0 ab 39 18 16 03 03 00  cd 0c 00 00 c9 03 00 17  |..9.............|
+000002e0  41 04 62 2a a7 2d 1f 7a  8d 7e 8a 9e 84 db df e2  |A.b*.-.z.~......|
+000002f0  7c 35 d8 a1 9f ec 23 ef  c7 c2 9a c5 45 02 6f eb  ||5....#.....E.o.|
+00000300  24 ed 77 e1 ca fe 9a be  06 1e ea 30 5a e7 13 00  |$.w........0Z...|
+00000310  47 52 a4 a2 d8 ee 9d 4e  87 f5 48 83 6f 5d 8e 02  |GR.....N..H.o]..|
+00000320  ff f5 04 01 00 80 19 f6  63 a1 47 d1 cf 4d 28 73  |........c.G..M(s|
+00000330  4e 31 03 78 b5 17 ba 53  64 d0 b8 3f 04 77 9d 6b  |N1.x...Sd..?.w.k|
+00000340  85 d0 d4 1e 02 90 b9 ab  10 dc d7 b1 79 1b 12 80  |............y...|
+00000350  e1 5a 4b 69 80 2d 2a 37  4c fd 72 a9 c3 8e 2a 1f  |.ZKi.-*7L.r...*.|
+00000360  1a 3f 74 49 c6 49 ce 2f  02 58 3f 68 f0 f6 b5 8a  |.?tI.I./.X?h....|
+00000370  16 11 8b 63 15 6a f2 91  f1 74 a8 f0 6d dc 91 0a  |...c.j...t..m...|
+00000380  b4 e2 4e 10 14 1d b9 da  05 29 bf 31 30 ee 7d a5  |..N......).10.}.|
+00000390  75 4e da ff db 43 04 a7  55 4b dd 93 4c 5f 32 be  |uN...C..UK..L_2.|
+000003a0  e9 23 c9 a1 23 86 16 03  03 00 04 0e 00 00 00     |.#..#..........|
+>>> Flow 3 (client to server)
+00000000  16 03 03 00 46 10 00 00  42 41 04 1e 18 37 ef 0d  |....F...BA...7..|
+00000010  19 51 88 35 75 71 b5 e5  54 5b 12 2e 8f 09 67 fd  |.Q.5uq..T[....g.|
+00000020  a7 24 20 3e b2 56 1c ce  97 28 5e f8 2b 2d 4f 9e  |.$ >.V...(^.+-O.|
+00000030  f1 07 9f 6c 4b 5b 83 56  e2 32 42 e9 58 b6 d7 49  |...lK[.V.2B.X..I|
+00000040  a6 b5 68 1a 41 03 56 6b  dc 5a 89 14 03 03 00 01  |..h.A.Vk.Z......|
+00000050  01 16 03 03 00 28 00 00  00 00 00 00 00 00 d4 cb  |.....(..........|
+00000060  e2 c0 1e fe cb b0 d6 fe  da 7c 8f 8c b2 2f f7 c1  |.........|.../..|
+00000070  3d e9 52 6e 70 c1 13 13  87 ff 12 85 6c 2c        |=.Rnp.......l,|
+>>> Flow 4 (server to client)
+00000000  14 03 03 00 01 01 16 03  03 00 28 0a 86 ff b2 73  |..........(....s|
+00000010  35 40 a1 89 9f 21 1f 0b  2f 79 50 70 eb 74 e1 2f  |5@...!../yPp.t./|
+00000020  4d bc 5c 3c 85 0b 60 cc  73 36 e4 08 01 0a 4c 75  |M.\<..`.s6....Lu|
+00000030  0f a2 9c                                          |...|
+>>> Flow 5 (client to server)
+00000000  17 03 03 00 1e 00 00 00  00 00 00 00 01 c9 78 b7  |..............x.|
+00000010  07 d1 a9 95 fc b4 aa 57  16 77 86 fb c7 a9 c6 12  |.......W.w......|
+00000020  bc bd 09                                          |...|
+>>> Flow 6 (server to client)
+00000000  16 03 03 00 1c 0a 86 ff  b2 73 35 40 a2 4d b1 9b  |.........s5@.M..|
+00000010  eb 51 76 71 6b b8 88 fe  21 60 bb 8b 2a cc e3 3e  |.Qvqk...!`..*..>|
+00000020  d5                                                |.|
+>>> Flow 7 (client to server)
+00000000  15 03 03 00 1a 00 00 00  00 00 00 00 02 0e da c6  |................|
+00000010  01 09 cc 0f bb 7d de c9  41 8d 30 b5 d5 b7 f2 15  |.....}..A.0.....|
+00000020  03 03 00 1a 00 00 00 00  00 00 00 03 a7 0e 24 98  |..............$.|
+00000030  32 62 1b a9 98 17 b6 b3  71 af 88 7a a3 6b        |2b......q..z.k|
diff --git a/libgo/go/crypto/tls/ticket.go b/libgo/go/crypto/tls/ticket.go
index 7be50ce68c9..3e7aa93c82a 100644
--- a/libgo/go/crypto/tls/ticket.go
+++ b/libgo/go/crypto/tls/ticket.go
@@ -126,11 +126,7 @@ func (s *sessionState) unmarshal(data []byte) bool {
 		data = data[certLen:]
 	}
 
-	if len(data) > 0 {
-		return false
-	}
-
-	return true
+	return len(data) == 0
 }
 
 func (c *Conn) encryptTicket(state *sessionState) ([]byte, error) {
diff --git a/libgo/go/crypto/tls/tls.go b/libgo/go/crypto/tls/tls.go
index 4bedd7682d3..8eef884a0f1 100644
--- a/libgo/go/crypto/tls/tls.go
+++ b/libgo/go/crypto/tls/tls.go
@@ -47,14 +47,13 @@ type listener struct {
 }
 
 // Accept waits for and returns the next incoming TLS connection.
-// The returned connection c is a *tls.Conn.
-func (l *listener) Accept() (c net.Conn, err error) {
-	c, err = l.Listener.Accept()
+// The returned connection is of type *Conn.
+func (l *listener) Accept() (net.Conn, error) {
+	c, err := l.Listener.Accept()
 	if err != nil {
-		return
+		return nil, err
 	}
-	c = Server(c, l.config)
-	return
+	return Server(c, l.config), nil
 }
 
 // NewListener creates a Listener which accepts connections from an inner
@@ -136,9 +135,9 @@ func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*
 	// from the hostname we're connecting to.
 	if config.ServerName == "" {
 		// Make a copy to avoid polluting argument or default.
-		c := *config
+		c := config.clone()
 		c.ServerName = hostname
-		config = &c
+		config = c
 	}
 
 	conn := Client(rawConn, config)
@@ -171,10 +170,11 @@ func Dial(network, addr string, config *Config) (*Conn, error) {
 	return DialWithDialer(new(net.Dialer), network, addr, config)
 }
 
-// LoadX509KeyPair reads and parses a public/private key pair from a pair of
-// files. The files must contain PEM encoded data. On successful return,
-// Certificate.Leaf will be nil because the parsed form of the certificate is
-// not retained.
+// LoadX509KeyPair reads and parses a public/private key pair from a pair
+// of files. The files must contain PEM encoded data. The certificate file
+// may contain intermediate certificates following the leaf certificate to
+// form a certificate chain. On successful return, Certificate.Leaf will
+// be nil because the parsed form of the certificate is not retained.
 func LoadX509KeyPair(certFile, keyFile string) (Certificate, error) {
 	certPEMBlock, err := ioutil.ReadFile(certFile)
 	if err != nil {
@@ -210,12 +210,12 @@ func X509KeyPair(certPEMBlock, keyPEMBlock []byte) (Certificate, error) {
 
 	if len(cert.Certificate) == 0 {
 		if len(skippedBlockTypes) == 0 {
-			return fail(errors.New("crypto/tls: failed to find any PEM data in certificate input"))
-		} else if len(skippedBlockTypes) == 1 && strings.HasSuffix(skippedBlockTypes[0], "PRIVATE KEY") {
-			return fail(errors.New("crypto/tls: failed to find certificate PEM data in certificate input, but did find a private key; PEM inputs may have been switched"))
-		} else {
-			return fail(fmt.Errorf("crypto/tls: failed to find \"CERTIFICATE\" PEM block in certificate input after skipping PEM blocks of the following types: %v", skippedBlockTypes))
+			return fail(errors.New("tls: failed to find any PEM data in certificate input"))
+		}
+		if len(skippedBlockTypes) == 1 && strings.HasSuffix(skippedBlockTypes[0], "PRIVATE KEY") {
+			return fail(errors.New("tls: failed to find certificate PEM data in certificate input, but did find a private key; PEM inputs may have been switched"))
 		}
+		return fail(fmt.Errorf("tls: failed to find \"CERTIFICATE\" PEM block in certificate input after skipping PEM blocks of the following types: %v", skippedBlockTypes))
 	}
 
 	skippedBlockTypes = skippedBlockTypes[:0]
@@ -224,12 +224,12 @@ func X509KeyPair(certPEMBlock, keyPEMBlock []byte) (Certificate, error) {
 		keyDERBlock, keyPEMBlock = pem.Decode(keyPEMBlock)
 		if keyDERBlock == nil {
 			if len(skippedBlockTypes) == 0 {
-				return fail(errors.New("crypto/tls: failed to find any PEM data in key input"))
-			} else if len(skippedBlockTypes) == 1 && skippedBlockTypes[0] == "CERTIFICATE" {
-				return fail(errors.New("crypto/tls: found a certificate rather than a key in the PEM for the private key"))
-			} else {
-				return fail(fmt.Errorf("crypto/tls: failed to find PEM block with type ending in \"PRIVATE KEY\" in key input after skipping PEM blocks of the following types: %v", skippedBlockTypes))
+				return fail(errors.New("tls: failed to find any PEM data in key input"))
 			}
+			if len(skippedBlockTypes) == 1 && skippedBlockTypes[0] == "CERTIFICATE" {
+				return fail(errors.New("tls: found a certificate rather than a key in the PEM for the private key"))
+			}
+			return fail(fmt.Errorf("tls: failed to find PEM block with type ending in \"PRIVATE KEY\" in key input after skipping PEM blocks of the following types: %v", skippedBlockTypes))
 		}
 		if keyDERBlock.Type == "PRIVATE KEY" || strings.HasSuffix(keyDERBlock.Type, " PRIVATE KEY") {
 			break
@@ -254,22 +254,21 @@ func X509KeyPair(certPEMBlock, keyPEMBlock []byte) (Certificate, error) {
 	case *rsa.PublicKey:
 		priv, ok := cert.PrivateKey.(*rsa.PrivateKey)
 		if !ok {
-			return fail(errors.New("crypto/tls: private key type does not match public key type"))
+			return fail(errors.New("tls: private key type does not match public key type"))
 		}
 		if pub.N.Cmp(priv.N) != 0 {
-			return fail(errors.New("crypto/tls: private key does not match public key"))
+			return fail(errors.New("tls: private key does not match public key"))
 		}
 	case *ecdsa.PublicKey:
 		priv, ok := cert.PrivateKey.(*ecdsa.PrivateKey)
 		if !ok {
-			return fail(errors.New("crypto/tls: private key type does not match public key type"))
-
+			return fail(errors.New("tls: private key type does not match public key type"))
 		}
 		if pub.X.Cmp(priv.X) != 0 || pub.Y.Cmp(priv.Y) != 0 {
-			return fail(errors.New("crypto/tls: private key does not match public key"))
+			return fail(errors.New("tls: private key does not match public key"))
 		}
 	default:
-		return fail(errors.New("crypto/tls: unknown public key algorithm"))
+		return fail(errors.New("tls: unknown public key algorithm"))
 	}
 
 	return cert, nil
@@ -287,12 +286,12 @@ func parsePrivateKey(der []byte) (crypto.PrivateKey, error) {
 		case *rsa.PrivateKey, *ecdsa.PrivateKey:
 			return key, nil
 		default:
-			return nil, errors.New("crypto/tls: found unknown private key type in PKCS#8 wrapping")
+			return nil, errors.New("tls: found unknown private key type in PKCS#8 wrapping")
 		}
 	}
 	if key, err := x509.ParseECPrivateKey(der); err == nil {
 		return key, nil
 	}
 
-	return nil, errors.New("crypto/tls: failed to parse private key")
+	return nil, errors.New("tls: failed to parse private key")
 }
diff --git a/libgo/go/crypto/tls/tls_test.go b/libgo/go/crypto/tls/tls_test.go
index 5cc14278a06..48b46a003a6 100644
--- a/libgo/go/crypto/tls/tls_test.go
+++ b/libgo/go/crypto/tls/tls_test.go
@@ -6,13 +6,19 @@ package tls
 
 import (
 	"bytes"
+	"crypto/x509"
 	"errors"
 	"fmt"
 	"internal/testenv"
 	"io"
+	"math"
+	"math/rand"
 	"net"
+	"os"
+	"reflect"
 	"strings"
 	"testing"
+	"testing/quick"
 	"time"
 )
 
@@ -146,7 +152,7 @@ func TestX509MixedKeyPair(t *testing.T) {
 	}
 }
 
-func newLocalListener(t *testing.T) net.Listener {
+func newLocalListener(t testing.TB) net.Listener {
 	ln, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
 		ln, err = net.Listen("tcp6", "[::1]:0")
@@ -188,18 +194,25 @@ func TestDialTimeout(t *testing.T) {
 		t.Fatal("DialWithTimeout completed successfully")
 	}
 
-	if !strings.Contains(err.Error(), "timed out") {
-		t.Errorf("resulting error not a timeout: %s", err)
+	if !isTimeoutError(err) {
+		t.Errorf("resulting error not a timeout: %v\nType %T: %#v", err, err, err)
 	}
 }
 
+func isTimeoutError(err error) bool {
+	if ne, ok := err.(net.Error); ok {
+		return ne.Timeout()
+	}
+	return false
+}
+
 // tests that Conn.Read returns (non-zero, io.EOF) instead of
 // (non-zero, nil) when a Close (alertCloseNotify) is sitting right
 // behind the application data in the buffer.
 func TestConnReadNonzeroAndEOF(t *testing.T) {
 	// This test is racy: it assumes that after a write to a
 	// localhost TCP connection, the peer TCP connection can
-	// immediately read it.  Because it's racy, we skip this test
+	// immediately read it. Because it's racy, we skip this test
 	// in short mode, and then retry it several times with an
 	// increasing sleep in between our final write (via srv.Close
 	// below) and the following read.
@@ -228,8 +241,8 @@ func testConnReadNonzeroAndEOF(t *testing.T, delay time.Duration) error {
 			srvCh <- nil
 			return
 		}
-		serverConfig := *testConfig
-		srv := Server(sconn, &serverConfig)
+		serverConfig := testConfig.clone()
+		srv := Server(sconn, serverConfig)
 		if err := srv.Handshake(); err != nil {
 			serr = fmt.Errorf("handshake: %v", err)
 			srvCh <- nil
@@ -238,8 +251,8 @@ func testConnReadNonzeroAndEOF(t *testing.T, delay time.Duration) error {
 		srvCh <- srv
 	}()
 
-	clientConfig := *testConfig
-	conn, err := Dial("tcp", ln.Addr().String(), &clientConfig)
+	clientConfig := testConfig.clone()
+	conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -282,8 +295,8 @@ func TestTLSUniqueMatches(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			serverConfig := *testConfig
-			srv := Server(sconn, &serverConfig)
+			serverConfig := testConfig.clone()
+			srv := Server(sconn, serverConfig)
 			if err := srv.Handshake(); err != nil {
 				t.Fatal(err)
 			}
@@ -291,9 +304,9 @@ func TestTLSUniqueMatches(t *testing.T) {
 		}
 	}()
 
-	clientConfig := *testConfig
+	clientConfig := testConfig.clone()
 	clientConfig.ClientSessionCache = NewLRUClientSessionCache(1)
-	conn, err := Dial("tcp", ln.Addr().String(), &clientConfig)
+	conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -302,7 +315,7 @@ func TestTLSUniqueMatches(t *testing.T) {
 	}
 	conn.Close()
 
-	conn, err = Dial("tcp", ln.Addr().String(), &clientConfig)
+	conn, err = Dial("tcp", ln.Addr().String(), clientConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -381,8 +394,8 @@ func TestConnCloseBreakingWrite(t *testing.T) {
 			srvCh <- nil
 			return
 		}
-		serverConfig := *testConfig
-		srv := Server(sconn, &serverConfig)
+		serverConfig := testConfig.clone()
+		srv := Server(sconn, serverConfig)
 		if err := srv.Handshake(); err != nil {
 			serr = fmt.Errorf("handshake: %v", err)
 			srvCh <- nil
@@ -401,8 +414,8 @@ func TestConnCloseBreakingWrite(t *testing.T) {
 		Conn: cconn,
 	}
 
-	clientConfig := *testConfig
-	tconn := Client(conn, &clientConfig)
+	clientConfig := testConfig.clone()
+	tconn := Client(conn, clientConfig)
 	if err := tconn.Handshake(); err != nil {
 		t.Fatal(err)
 	}
@@ -445,6 +458,58 @@ func TestConnCloseBreakingWrite(t *testing.T) {
 	}
 }
 
+func TestClone(t *testing.T) {
+	var c1 Config
+	v := reflect.ValueOf(&c1).Elem()
+
+	rnd := rand.New(rand.NewSource(time.Now().Unix()))
+	typ := v.Type()
+	for i := 0; i < typ.NumField(); i++ {
+		f := v.Field(i)
+		if !f.CanSet() {
+			// unexported field; not cloned.
+			continue
+		}
+
+		// testing/quick can't handle functions or interfaces.
+		fn := typ.Field(i).Name
+		switch fn {
+		case "Rand":
+			f.Set(reflect.ValueOf(io.Reader(os.Stdin)))
+			continue
+		case "Time", "GetCertificate":
+			// DeepEqual can't compare functions.
+			continue
+		case "Certificates":
+			f.Set(reflect.ValueOf([]Certificate{
+				{Certificate: [][]byte{[]byte{'b'}}},
+			}))
+			continue
+		case "NameToCertificate":
+			f.Set(reflect.ValueOf(map[string]*Certificate{"a": nil}))
+			continue
+		case "RootCAs", "ClientCAs":
+			f.Set(reflect.ValueOf(x509.NewCertPool()))
+			continue
+		case "ClientSessionCache":
+			f.Set(reflect.ValueOf(NewLRUClientSessionCache(10)))
+			continue
+		}
+
+		q, ok := quick.Value(f.Type(), rnd)
+		if !ok {
+			t.Fatalf("quick.Value failed on field %s", fn)
+		}
+		f.Set(q)
+	}
+
+	c2 := c1.clone()
+
+	if !reflect.DeepEqual(&c1, c2) {
+		t.Errorf("clone failed to copy a field")
+	}
+}
+
 // changeImplConn is a net.Conn which can change its Write and Close
 // methods.
 type changeImplConn struct {
@@ -466,3 +531,161 @@ func (w *changeImplConn) Close() error {
 	}
 	return w.Conn.Close()
 }
+
+func throughput(b *testing.B, totalBytes int64, dynamicRecordSizingDisabled bool) {
+	ln := newLocalListener(b)
+	defer ln.Close()
+
+	N := b.N
+
+	// Less than 64KB because Windows appears to use a TCP rwin < 64KB.
+	// See Issue #15899.
+	const bufsize = 32 << 10
+
+	go func() {
+		buf := make([]byte, bufsize)
+		for i := 0; i < N; i++ {
+			sconn, err := ln.Accept()
+			if err != nil {
+				// panic rather than synchronize to avoid benchmark overhead
+				// (cannot call b.Fatal in goroutine)
+				panic(fmt.Errorf("accept: %v", err))
+			}
+			serverConfig := testConfig.clone()
+			serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+			srv := Server(sconn, serverConfig)
+			if err := srv.Handshake(); err != nil {
+				panic(fmt.Errorf("handshake: %v", err))
+			}
+			if _, err := io.CopyBuffer(srv, srv, buf); err != nil {
+				panic(fmt.Errorf("copy buffer: %v", err))
+			}
+		}
+	}()
+
+	b.SetBytes(totalBytes)
+	clientConfig := testConfig.clone()
+	clientConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+
+	buf := make([]byte, bufsize)
+	chunks := int(math.Ceil(float64(totalBytes) / float64(len(buf))))
+	for i := 0; i < N; i++ {
+		conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+		if err != nil {
+			b.Fatal(err)
+		}
+		for j := 0; j < chunks; j++ {
+			_, err := conn.Write(buf)
+			if err != nil {
+				b.Fatal(err)
+			}
+			_, err = io.ReadFull(conn, buf)
+			if err != nil {
+				b.Fatal(err)
+			}
+		}
+		conn.Close()
+	}
+}
+
+func BenchmarkThroughput(b *testing.B) {
+	for _, mode := range []string{"Max", "Dynamic"} {
+		for size := 1; size <= 64; size <<= 1 {
+			name := fmt.Sprintf("%sPacket/%dMB", mode, size)
+			b.Run(name, func(b *testing.B) {
+				throughput(b, int64(size<<20), mode == "Max")
+			})
+		}
+	}
+}
+
+type slowConn struct {
+	net.Conn
+	bps int
+}
+
+func (c *slowConn) Write(p []byte) (int, error) {
+	if c.bps == 0 {
+		panic("too slow")
+	}
+	t0 := time.Now()
+	wrote := 0
+	for wrote < len(p) {
+		time.Sleep(100 * time.Microsecond)
+		allowed := int(time.Since(t0).Seconds()*float64(c.bps)) / 8
+		if allowed > len(p) {
+			allowed = len(p)
+		}
+		if wrote < allowed {
+			n, err := c.Conn.Write(p[wrote:allowed])
+			wrote += n
+			if err != nil {
+				return wrote, err
+			}
+		}
+	}
+	return len(p), nil
+}
+
+func latency(b *testing.B, bps int, dynamicRecordSizingDisabled bool) {
+	ln := newLocalListener(b)
+	defer ln.Close()
+
+	N := b.N
+
+	go func() {
+		for i := 0; i < N; i++ {
+			sconn, err := ln.Accept()
+			if err != nil {
+				// panic rather than synchronize to avoid benchmark overhead
+				// (cannot call b.Fatal in goroutine)
+				panic(fmt.Errorf("accept: %v", err))
+			}
+			serverConfig := testConfig.clone()
+			serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+			srv := Server(&slowConn{sconn, bps}, serverConfig)
+			if err := srv.Handshake(); err != nil {
+				panic(fmt.Errorf("handshake: %v", err))
+			}
+			io.Copy(srv, srv)
+		}
+	}()
+
+	clientConfig := testConfig.clone()
+	clientConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
+
+	buf := make([]byte, 16384)
+	peek := make([]byte, 1)
+
+	for i := 0; i < N; i++ {
+		conn, err := Dial("tcp", ln.Addr().String(), clientConfig)
+		if err != nil {
+			b.Fatal(err)
+		}
+		// make sure we're connected and previous connection has stopped
+		if _, err := conn.Write(buf[:1]); err != nil {
+			b.Fatal(err)
+		}
+		if _, err := io.ReadFull(conn, peek); err != nil {
+			b.Fatal(err)
+		}
+		if _, err := conn.Write(buf); err != nil {
+			b.Fatal(err)
+		}
+		if _, err = io.ReadFull(conn, peek); err != nil {
+			b.Fatal(err)
+		}
+		conn.Close()
+	}
+}
+
+func BenchmarkLatency(b *testing.B) {
+	for _, mode := range []string{"Max", "Dynamic"} {
+		for _, kbps := range []int{200, 500, 1000, 2000, 5000} {
+			name := fmt.Sprintf("%sPacket/%dkbps", mode, kbps)
+			b.Run(name, func(b *testing.B) {
+				latency(b, kbps*1000, mode == "Max")
+			})
+		}
+	}
+}
diff --git a/libgo/go/crypto/x509/cert_pool.go b/libgo/go/crypto/x509/cert_pool.go
index 2362e84688d..59ab8871054 100644
--- a/libgo/go/crypto/x509/cert_pool.go
+++ b/libgo/go/crypto/x509/cert_pool.go
@@ -6,6 +6,8 @@ package x509
 
 import (
 	"encoding/pem"
+	"errors"
+	"runtime"
 )
 
 // CertPool is a set of certificates.
@@ -18,12 +20,22 @@ type CertPool struct {
 // NewCertPool returns a new, empty CertPool.
 func NewCertPool() *CertPool {
 	return &CertPool{
-		make(map[string][]int),
-		make(map[string][]int),
-		nil,
+		bySubjectKeyId: make(map[string][]int),
+		byName:         make(map[string][]int),
 	}
 }
 
+// SystemCertPool returns a copy of the system cert pool.
+//
+// Any mutations to the returned pool are not written to disk and do
+// not affect any other pool.
+func SystemCertPool() (*CertPool, error) {
+	if runtime.GOOS == "windows" {
+		return nil, errors.New("crypto/x509: system root pool is not available on Windows")
+	}
+	return loadSystemRoots()
+}
+
 // findVerifiedParents attempts to find certificates in s which have signed the
 // given certificate. If any candidates were rejected then errCert will be set
 // to one of them, arbitrarily, and err will contain the reason that it was
@@ -107,10 +119,10 @@ func (s *CertPool) AppendCertsFromPEM(pemCerts []byte) (ok bool) {
 
 // Subjects returns a list of the DER-encoded subjects of
 // all of the certificates in the pool.
-func (s *CertPool) Subjects() (res [][]byte) {
-	res = make([][]byte, len(s.certs))
+func (s *CertPool) Subjects() [][]byte {
+	res := make([][]byte, len(s.certs))
 	for i, c := range s.certs {
 		res[i] = c.RawSubject
 	}
-	return
+	return res
 }
diff --git a/libgo/go/crypto/x509/pem_decrypt.go b/libgo/go/crypto/x509/pem_decrypt.go
index 49ceadb4366..0388d63e149 100644
--- a/libgo/go/crypto/x509/pem_decrypt.go
+++ b/libgo/go/crypto/x509/pem_decrypt.go
@@ -42,7 +42,7 @@ type rfc1423Algo struct {
 }
 
 // rfc1423Algos holds a slice of the possible ways to encrypt a PEM
-// block.  The ivSize numbers were taken from the OpenSSL source.
+// block. The ivSize numbers were taken from the OpenSSL source.
 var rfc1423Algos = []rfc1423Algo{{
 	cipher:     PEMCipherDES,
 	name:       "DES-CBC",
diff --git a/libgo/go/crypto/x509/pkcs1.go b/libgo/go/crypto/x509/pkcs1.go
index acebe351398..df20a442049 100644
--- a/libgo/go/crypto/x509/pkcs1.go
+++ b/libgo/go/crypto/x509/pkcs1.go
@@ -36,15 +36,14 @@ type pkcs1AdditionalRSAPrime struct {
 }
 
 // ParsePKCS1PrivateKey returns an RSA private key from its ASN.1 PKCS#1 DER encoded form.
-func ParsePKCS1PrivateKey(der []byte) (key *rsa.PrivateKey, err error) {
+func ParsePKCS1PrivateKey(der []byte) (*rsa.PrivateKey, error) {
 	var priv pkcs1PrivateKey
 	rest, err := asn1.Unmarshal(der, &priv)
 	if len(rest) > 0 {
-		err = asn1.SyntaxError{Msg: "trailing data"}
-		return
+		return nil, asn1.SyntaxError{Msg: "trailing data"}
 	}
 	if err != nil {
-		return
+		return nil, err
 	}
 
 	if priv.Version > 1 {
@@ -55,7 +54,7 @@ func ParsePKCS1PrivateKey(der []byte) (key *rsa.PrivateKey, err error) {
 		return nil, errors.New("x509: private key contains zero or negative value")
 	}
 
-	key = new(rsa.PrivateKey)
+	key := new(rsa.PrivateKey)
 	key.PublicKey = rsa.PublicKey{
 		E: priv.E,
 		N: priv.N,
@@ -80,7 +79,7 @@ func ParsePKCS1PrivateKey(der []byte) (key *rsa.PrivateKey, err error) {
 	}
 	key.Precompute()
 
-	return
+	return key, nil
 }
 
 // MarshalPKCS1PrivateKey converts a private key to ASN.1 DER encoded form.
diff --git a/libgo/go/crypto/x509/pkcs8.go b/libgo/go/crypto/x509/pkcs8.go
index ba19989cba1..b304a3f63c9 100644
--- a/libgo/go/crypto/x509/pkcs8.go
+++ b/libgo/go/crypto/x509/pkcs8.go
@@ -13,7 +13,7 @@ import (
 
 // pkcs8 reflects an ASN.1, PKCS#8 PrivateKey. See
 // ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-8/pkcs-8v1_2.asn
-// and RFC5208.
+// and RFC 5208.
 type pkcs8 struct {
 	Version    int
 	Algo       pkix.AlgorithmIdentifier
@@ -21,8 +21,8 @@ type pkcs8 struct {
 	// optional attributes omitted.
 }
 
-// ParsePKCS8PrivateKey parses an unencrypted, PKCS#8 private key. See
-// http://www.rsa.com/rsalabs/node.asp?id=2130 and RFC5208.
+// ParsePKCS8PrivateKey parses an unencrypted, PKCS#8 private key.
+// See RFC 5208.
 func ParsePKCS8PrivateKey(der []byte) (key interface{}, err error) {
 	var privKey pkcs8
 	if _, err := asn1.Unmarshal(der, &privKey); err != nil {
diff --git a/libgo/go/crypto/x509/pkix/pkix.go b/libgo/go/crypto/x509/pkix/pkix.go
index 1b3e3c0440e..faad4061fc7 100644
--- a/libgo/go/crypto/x509/pkix/pkix.go
+++ b/libgo/go/crypto/x509/pkix/pkix.go
@@ -177,7 +177,7 @@ func (certList *CertificateList) HasExpired(now time.Time) bool {
 // 5280, section 5.1.
 type TBSCertificateList struct {
 	Raw                 asn1.RawContent
-	Version             int `asn1:"optional,default:1"`
+	Version             int `asn1:"optional,default:0"`
 	Signature           AlgorithmIdentifier
 	Issuer              RDNSequence
 	ThisUpdate          time.Time
diff --git a/libgo/go/crypto/x509/root.go b/libgo/go/crypto/x509/root.go
index 8aae14e09ee..787d955be47 100644
--- a/libgo/go/crypto/x509/root.go
+++ b/libgo/go/crypto/x509/root.go
@@ -7,11 +7,16 @@ package x509
 import "sync"
 
 var (
-	once        sync.Once
-	systemRoots *CertPool
+	once           sync.Once
+	systemRoots    *CertPool
+	systemRootsErr error
 )
 
 func systemRootsPool() *CertPool {
 	once.Do(initSystemRoots)
 	return systemRoots
 }
+
+func initSystemRoots() {
+	systemRoots, systemRootsErr = loadSystemRoots()
+}
diff --git a/libgo/go/crypto/x509/root_cgo_darwin.go b/libgo/go/crypto/x509/root_cgo_darwin.go
index bf4a5cdfeee..0e2fb357ee9 100644
--- a/libgo/go/crypto/x509/root_cgo_darwin.go
+++ b/libgo/go/crypto/x509/root_cgo_darwin.go
@@ -21,59 +21,91 @@ package x509
 // Note: The CFDataRef returned in pemRoots must be released (using CFRelease) after
 // we've consumed its content.
 int FetchPEMRoots(CFDataRef *pemRoots) {
-	if (pemRoots == NULL) {
-		return -1;
-	}
+	// Get certificates from all domains, not just System, this lets
+	// the user add CAs to their "login" keychain, and Admins to add
+	// to the "System" keychain
+	SecTrustSettingsDomain domains[] = { kSecTrustSettingsDomainSystem,
+					     kSecTrustSettingsDomainAdmin,
+					     kSecTrustSettingsDomainUser };
 
-	CFArrayRef certs = NULL;
-	OSStatus err = SecTrustCopyAnchorCertificates(&certs);
-	if (err != noErr) {
+	int numDomains = sizeof(domains)/sizeof(SecTrustSettingsDomain);
+	if (pemRoots == NULL) {
 		return -1;
 	}
 
 	CFMutableDataRef combinedData = CFDataCreateMutable(kCFAllocatorDefault, 0);
-	int i, ncerts = CFArrayGetCount(certs);
-	for (i = 0; i < ncerts; i++) {
-		CFDataRef data = NULL;
-		SecCertificateRef cert = (SecCertificateRef)CFArrayGetValueAtIndex(certs, i);
-		if (cert == NULL) {
-			continue;
-		}
-
-		// Note: SecKeychainItemExport is deprecated as of 10.7 in favor of SecItemExport.
-		// Once we support weak imports via cgo we should prefer that, and fall back to this
-		// for older systems.
-		err = SecKeychainItemExport(cert, kSecFormatX509Cert, kSecItemPemArmour, NULL, &data);
+	for (int i = 0; i < numDomains; i++) {
+		CFArrayRef certs = NULL;
+		// Only get certificates from domain that are trusted
+		OSStatus err = SecTrustSettingsCopyCertificates(domains[i], &certs);
 		if (err != noErr) {
 			continue;
 		}
 
-		if (data != NULL) {
-			CFDataAppendBytes(combinedData, CFDataGetBytePtr(data), CFDataGetLength(data));
-			CFRelease(data);
-		}
-	}
+		int numCerts = CFArrayGetCount(certs);
+		for (int j = 0; j < numCerts; j++) {
+			CFDataRef data = NULL;
+			CFErrorRef errRef = NULL;
+			SecCertificateRef cert = (SecCertificateRef)CFArrayGetValueAtIndex(certs, j);
+			if (cert == NULL) {
+				continue;
+			}
+			// We only want to add Root CAs, so make sure Subject and Issuer Name match
+			CFDataRef subjectName = SecCertificateCopyNormalizedSubjectContent(cert, &errRef);
+			if (errRef != NULL) {
+				CFRelease(errRef);
+				continue;
+			}
+			CFDataRef issuerName = SecCertificateCopyNormalizedIssuerContent(cert, &errRef);
+			if (errRef != NULL) {
+				CFRelease(subjectName);
+				CFRelease(errRef);
+				continue;
+			}
+			Boolean equal = CFEqual(subjectName, issuerName);
+			CFRelease(subjectName);
+			CFRelease(issuerName);
+			if (!equal) {
+				continue;
+			}
 
-	CFRelease(certs);
+			// Note: SecKeychainItemExport is deprecated as of 10.7 in favor of SecItemExport.
+			// Once we support weak imports via cgo we should prefer that, and fall back to this
+			// for older systems.
+			err = SecKeychainItemExport(cert, kSecFormatX509Cert, kSecItemPemArmour, NULL, &data);
+			if (err != noErr) {
+				continue;
+			}
 
+			if (data != NULL) {
+				CFDataAppendBytes(combinedData, CFDataGetBytePtr(data), CFDataGetLength(data));
+				CFRelease(data);
+			}
+		}
+		CFRelease(certs);
+	}
 	*pemRoots = combinedData;
 	return 0;
 }
 */
 import "C"
-import "unsafe"
+import (
+	"errors"
+	"unsafe"
+)
 
-func initSystemRoots() {
+func loadSystemRoots() (*CertPool, error) {
 	roots := NewCertPool()
 
 	var data C.CFDataRef = nil
 	err := C.FetchPEMRoots(&data)
 	if err == -1 {
-		return
+		// TODO: better error message
+		return nil, errors.New("crypto/x509: failed to load darwin system roots with cgo")
 	}
 
 	defer C.CFRelease(C.CFTypeRef(data))
 	buf := C.GoBytes(unsafe.Pointer(C.CFDataGetBytePtr(data)), C.int(C.CFDataGetLength(data)))
 	roots.AppendCertsFromPEM(buf)
-	systemRoots = roots
+	return roots, nil
 }
diff --git a/libgo/go/crypto/x509/root_darwin_arm_gen.go b/libgo/go/crypto/x509/root_darwin_arm_gen.go
index 5817158c33b..fc2488adc6f 100644
--- a/libgo/go/crypto/x509/root_darwin_arm_gen.go
+++ b/libgo/go/crypto/x509/root_darwin_arm_gen.go
@@ -184,8 +184,9 @@ const header = `
 
 package x509
 
-func initSystemRoots() {
-	systemRoots = NewCertPool()
-	systemRoots.AppendCertsFromPEM([]byte(systemRootsPEM))
+func loadSystemRoots() (*CertPool, error) {
+	p := NewCertPool()
+	p.AppendCertsFromPEM([]byte(systemRootsPEM))
+	return p, nil
 }
 `
diff --git a/libgo/go/crypto/x509/root_darwin_armx.go b/libgo/go/crypto/x509/root_darwin_armx.go
index 37675b48a39..ad1c53d8a42 100644
--- a/libgo/go/crypto/x509/root_darwin_armx.go
+++ b/libgo/go/crypto/x509/root_darwin_armx.go
@@ -10,9 +10,10 @@
 
 package x509
 
-func initSystemRoots() {
-	systemRoots = NewCertPool()
-	systemRoots.AppendCertsFromPEM([]byte(systemRootsPEM))
+func loadSystemRoots() (*CertPool, error) {
+	p := NewCertPool()
+	p.AppendCertsFromPEM([]byte(systemRootsPEM))
+	return p, nil
 }
 
 const systemRootsPEM = `
diff --git a/libgo/go/crypto/x509/root_nocgo_darwin.go b/libgo/go/crypto/x509/root_nocgo_darwin.go
index d00e2576624..2ac4666aff6 100644
--- a/libgo/go/crypto/x509/root_nocgo_darwin.go
+++ b/libgo/go/crypto/x509/root_nocgo_darwin.go
@@ -6,6 +6,6 @@
 
 package x509
 
-func initSystemRoots() {
-	systemRoots, _ = execSecurityRoots()
+func loadSystemRoots() (*CertPool, error) {
+	return execSecurityRoots()
 }
diff --git a/libgo/go/crypto/x509/root_plan9.go b/libgo/go/crypto/x509/root_plan9.go
index 9965caadee3..ebeb7dfccd8 100644
--- a/libgo/go/crypto/x509/root_plan9.go
+++ b/libgo/go/crypto/x509/root_plan9.go
@@ -6,7 +6,10 @@
 
 package x509
 
-import "io/ioutil"
+import (
+	"io/ioutil"
+	"os"
+)
 
 // Possible certificate files; stop after finding one.
 var certFiles = []string{
@@ -17,17 +20,18 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	return nil, nil
 }
 
-func initSystemRoots() {
+func loadSystemRoots() (*CertPool, error) {
 	roots := NewCertPool()
+	var bestErr error
 	for _, file := range certFiles {
 		data, err := ioutil.ReadFile(file)
 		if err == nil {
 			roots.AppendCertsFromPEM(data)
-			systemRoots = roots
-			return
+			return roots, nil
+		}
+		if bestErr == nil || (os.IsNotExist(bestErr) && !os.IsNotExist(err)) {
+			bestErr = err
 		}
 	}
-
-	// All of the files failed to load. systemRoots will be nil which will
-	// trigger a specific error at verification time.
+	return nil, bestErr
 }
diff --git a/libgo/go/crypto/x509/root_unix.go b/libgo/go/crypto/x509/root_unix.go
index 9f06f9dabbe..7bcb3d63d1f 100644
--- a/libgo/go/crypto/x509/root_unix.go
+++ b/libgo/go/crypto/x509/root_unix.go
@@ -6,7 +6,10 @@
 
 package x509
 
-import "io/ioutil"
+import (
+	"io/ioutil"
+	"os"
+)
 
 // Possible directories with certificate files; stop after successfully
 // reading at least one file from a directory.
@@ -19,20 +22,26 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	return nil, nil
 }
 
-func initSystemRoots() {
+func loadSystemRoots() (*CertPool, error) {
 	roots := NewCertPool()
+	var firstErr error
 	for _, file := range certFiles {
 		data, err := ioutil.ReadFile(file)
 		if err == nil {
 			roots.AppendCertsFromPEM(data)
-			systemRoots = roots
-			return
+			return roots, nil
+		}
+		if firstErr == nil && !os.IsNotExist(err) {
+			firstErr = err
 		}
 	}
 
 	for _, directory := range certDirectories {
 		fis, err := ioutil.ReadDir(directory)
 		if err != nil {
+			if firstErr == nil && !os.IsNotExist(err) {
+				firstErr = err
+			}
 			continue
 		}
 		rootsAdded := false
@@ -43,11 +52,9 @@ func initSystemRoots() {
 			}
 		}
 		if rootsAdded {
-			systemRoots = roots
-			return
+			return roots, nil
 		}
 	}
 
-	// All of the files failed to load. systemRoots will be nil which will
-	// trigger a specific error at verification time.
+	return nil, firstErr
 }
diff --git a/libgo/go/crypto/x509/root_windows.go b/libgo/go/crypto/x509/root_windows.go
index 81018b78fe6..392c869012d 100644
--- a/libgo/go/crypto/x509/root_windows.go
+++ b/libgo/go/crypto/x509/root_windows.go
@@ -179,7 +179,7 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	}
 
 	// CertGetCertificateChain will traverse Windows's root stores
-	// in an attempt to build a verified certificate chain.  Once
+	// in an attempt to build a verified certificate chain. Once
 	// it has found a verified chain, it stops. MSDN docs on
 	// CERT_CHAIN_CONTEXT:
 	//
@@ -225,5 +225,4 @@ func (c *Certificate) systemVerify(opts *VerifyOptions) (chains [][]*Certificate
 	return chains, nil
 }
 
-func initSystemRoots() {
-}
+func loadSystemRoots() (*CertPool, error) { return nil, nil }
diff --git a/libgo/go/crypto/x509/sec1.go b/libgo/go/crypto/x509/sec1.go
index 1424dea99e5..33f376c072c 100644
--- a/libgo/go/crypto/x509/sec1.go
+++ b/libgo/go/crypto/x509/sec1.go
@@ -17,9 +17,9 @@ const ecPrivKeyVersion = 1
 
 // ecPrivateKey reflects an ASN.1 Elliptic Curve Private Key Structure.
 // References:
-//   RFC5915
+//   RFC 5915
 //   SEC1 - http://www.secg.org/sec1-v2.pdf
-// Per RFC5915 the NamedCurveOID is marked as ASN.1 OPTIONAL, however in
+// Per RFC 5915 the NamedCurveOID is marked as ASN.1 OPTIONAL, however in
 // most cases it is not.
 type ecPrivateKey struct {
 	Version       int
@@ -29,7 +29,7 @@ type ecPrivateKey struct {
 }
 
 // ParseECPrivateKey parses an ASN.1 Elliptic Curve Private Key Structure.
-func ParseECPrivateKey(der []byte) (key *ecdsa.PrivateKey, err error) {
+func ParseECPrivateKey(der []byte) (*ecdsa.PrivateKey, error) {
 	return parseECPrivateKey(nil, der)
 }
 
diff --git a/libgo/go/crypto/x509/verify.go b/libgo/go/crypto/x509/verify.go
index 27e9bbfbcc6..85c083fbb2c 100644
--- a/libgo/go/crypto/x509/verify.go
+++ b/libgo/go/crypto/x509/verify.go
@@ -117,10 +117,16 @@ func (e UnknownAuthorityError) Error() string {
 }
 
 // SystemRootsError results when we fail to load the system root certificates.
-type SystemRootsError struct{}
+type SystemRootsError struct {
+	Err error
+}
 
-func (SystemRootsError) Error() string {
-	return "x509: failed to load system roots and no roots provided"
+func (se SystemRootsError) Error() string {
+	msg := "x509: failed to load system roots and no roots provided"
+	if se.Err != nil {
+		return msg + "; " + se.Err.Error()
+	}
+	return msg
 }
 
 // errNotParsed is returned when a certificate without ASN.1 contents is
@@ -179,7 +185,7 @@ func (c *Certificate) isValid(certType int, currentChain []*Certificate, opts *V
 	// being valid for encryption only, but no-one noticed. Another
 	// European CA marked its signature keys as not being valid for
 	// signatures. A different CA marked its own trusted root certificate
-	// as being invalid for certificate signing.  Another national CA
+	// as being invalid for certificate signing. Another national CA
 	// distributed a certificate to be used to encrypt data for the
 	// country’s tax authority that was marked as only being usable for
 	// digital signatures but not for encryption. Yet another CA reversed
@@ -240,7 +246,7 @@ func (c *Certificate) Verify(opts VerifyOptions) (chains [][]*Certificate, err e
 	if opts.Roots == nil {
 		opts.Roots = systemRootsPool()
 		if opts.Roots == nil {
-			return nil, SystemRootsError{}
+			return nil, SystemRootsError{systemRootsErr}
 		}
 	}
 
diff --git a/libgo/go/crypto/x509/verify_test.go b/libgo/go/crypto/x509/verify_test.go
index 694c14023b8..bacf7ded29f 100644
--- a/libgo/go/crypto/x509/verify_test.go
+++ b/libgo/go/crypto/x509/verify_test.go
@@ -382,7 +382,7 @@ func testVerify(t *testing.T, useSystemRoots bool) {
 					continue
 				}
 				for k, cert := range chain {
-					if strings.Index(nameToKey(&cert.Subject), expectedChain[k]) == -1 {
+					if !strings.Contains(nameToKey(&cert.Subject), expectedChain[k]) {
 						continue TryNextExpected
 					}
 				}
@@ -650,50 +650,6 @@ um0ABj6y6koQOdjQK/W/7HW/lwLFCRsI3FU34oH7N4RDYiDK51ZLZer+bMEkkySh
 NOsF/5oirpt9P/FlUQqmMGqz9IgcgA38corog14=
 -----END CERTIFICATE-----`
 
-const startComRootSHA256 = `-----BEGIN CERTIFICATE-----
-MIIHhzCCBW+gAwIBAgIBLTANBgkqhkiG9w0BAQsFADB9MQswCQYDVQQGEwJJTDEW
-MBQGA1UEChMNU3RhcnRDb20gTHRkLjErMCkGA1UECxMiU2VjdXJlIERpZ2l0YWwg
-Q2VydGlmaWNhdGUgU2lnbmluZzEpMCcGA1UEAxMgU3RhcnRDb20gQ2VydGlmaWNh
-dGlvbiBBdXRob3JpdHkwHhcNMDYwOTE3MTk0NjM3WhcNMzYwOTE3MTk0NjM2WjB9
-MQswCQYDVQQGEwJJTDEWMBQGA1UEChMNU3RhcnRDb20gTHRkLjErMCkGA1UECxMi
-U2VjdXJlIERpZ2l0YWwgQ2VydGlmaWNhdGUgU2lnbmluZzEpMCcGA1UEAxMgU3Rh
-cnRDb20gQ2VydGlmaWNhdGlvbiBBdXRob3JpdHkwggIiMA0GCSqGSIb3DQEBAQUA
-A4ICDwAwggIKAoICAQDBiNsJvGxGfHiflXu1M5DycmLWwTYgIiRezul38kMKogZk
-pMyONvg45iPwbm2xPN1yo4UcodM9tDMr0y+v/uqwQVlntsQGfQqedIXWeUyAN3rf
-OQVSWff0G0ZDpNKFhdLDcfN1YjS6LIp/Ho/u7TTQEceWzVI9ujPW3U3eCztKS5/C
-Ji/6tRYccjV3yjxd5srhJosaNnZcAdt0FCX+7bWgiA/deMotHweXMAEtcnn6RtYT
-Kqi5pquDSR3l8u/d5AGOGAqPY1MWhWKpDhk6zLVmpsJrdAfkK+F2PrRt2PZE4XNi
-HzvEvqBTViVsUQn3qqvKv3b9bZvzndu/PWa8DFaqr5hIlTpL36dYUNk4dalb6kMM
-Av+Z6+hsTXBbKWWc3apdzK8BMewM69KN6Oqce+Zu9ydmDBpI125C4z/eIT574Q1w
-+2OqqGwaVLRcJXrJosmLFqa7LH4XXgVNWG4SHQHuEhANxjJ/GP/89PrNbpHoNkm+
-Gkhpi8KWTRoSsmkXwQqQ1vp5Iki/untp+HDH+no32NgN0nZPV/+Qt+OR0t3vwmC3
-Zzrd/qqc8NSLf3Iizsafl7b4r4qgEKjZ+xjGtrVcUjyJthkqcwEKDwOzEmDyei+B
-26Nu/yYwl/WL3YlXtq09s68rxbd2AvCl1iuahhQqcvbjM4xdCUsT37uMdBNSSwID
-AQABo4ICEDCCAgwwDwYDVR0TAQH/BAUwAwEB/zAOBgNVHQ8BAf8EBAMCAQYwHQYD
-VR0OBBYEFE4L7xqkQFulF2mHMMo0aEPQQa7yMB8GA1UdIwQYMBaAFE4L7xqkQFul
-F2mHMMo0aEPQQa7yMIIBWgYDVR0gBIIBUTCCAU0wggFJBgsrBgEEAYG1NwEBATCC
-ATgwLgYIKwYBBQUHAgEWImh0dHA6Ly93d3cuc3RhcnRzc2wuY29tL3BvbGljeS5w
-ZGYwNAYIKwYBBQUHAgEWKGh0dHA6Ly93d3cuc3RhcnRzc2wuY29tL2ludGVybWVk
-aWF0ZS5wZGYwgc8GCCsGAQUFBwICMIHCMCcWIFN0YXJ0IENvbW1lcmNpYWwgKFN0
-YXJ0Q29tKSBMdGQuMAMCAQEagZZMaW1pdGVkIExpYWJpbGl0eSwgcmVhZCB0aGUg
-c2VjdGlvbiAqTGVnYWwgTGltaXRhdGlvbnMqIG9mIHRoZSBTdGFydENvbSBDZXJ0
-aWZpY2F0aW9uIEF1dGhvcml0eSBQb2xpY3kgYXZhaWxhYmxlIGF0IGh0dHA6Ly93
-d3cuc3RhcnRzc2wuY29tL3BvbGljeS5wZGYwEQYJYIZIAYb4QgEBBAQDAgAHMDgG
-CWCGSAGG+EIBDQQrFilTdGFydENvbSBGcmVlIFNTTCBDZXJ0aWZpY2F0aW9uIEF1
-dGhvcml0eTANBgkqhkiG9w0BAQsFAAOCAgEAjo/n3JR5fPGFf59Jb2vKXfuM/gTF
-wWLRfUKKvFO3lANmMD+x5wqnUCBVJX92ehQN6wQOQOY+2IirByeDqXWmN3PH/UvS
-Ta0XQMhGvjt/UfzDtgUx3M2FIk5xt/JxXrAaxrqTi3iSSoX4eA+D/i+tLPfkpLst
-0OcNOrg+zvZ49q5HJMqjNTbOx8aHmNrs++myziebiMMEofYLWWivydsQD032ZGNc
-pRJvkrKTlMeIFw6Ttn5ii5B/q06f/ON1FE8qMt9bDeD1e5MNq6HPh+GlBEXoPBKl
-CcWw0bdT82AUuoVpaiF8H3VhFyAXe2w7QSlc4axa0c2Mm+tgHRns9+Ww2vl5GKVF
-P0lDV9LdJNUso/2RjSe15esUBppMeyG7Oq0wBhjA2MFrLH9ZXF2RsXAiV+uKa0hK
-1Q8p7MZAwC+ITGgBF3f0JBlPvfrhsiAhS90a2Cl9qrjeVOwhVYBsHvUwyKMQ5bLm
-KhQxw4UtjJixhlpPiVktucf3HMiKf8CdBUrmQk9io20ppB+Fq9vlgcitKj1MXVuE
-JnHEhV5xJMqlG2zYYdMa4FTbzrqpMrUi9nNBCV24F10OD5mQ1kfabwo6YigUZ4LZ
-8dCAWZvLMdibD4x3TrVoivJs9iQOLWxwxXPR3hTQcY+203sC9uO41Alua551hDnm
-fyWl8kgAwKQB2j8=
------END CERTIFICATE-----`
-
 const smimeLeaf = `-----BEGIN CERTIFICATE-----
 MIIFBjCCA+6gAwIBAgISESFvrjT8XcJTEe6rBlPptILlMA0GCSqGSIb3DQEBBQUA
 MFQxCzAJBgNVBAYTAkJFMRkwFwYDVQQKExBHbG9iYWxTaWduIG52LXNhMSowKAYD
diff --git a/libgo/go/crypto/x509/x509.go b/libgo/go/crypto/x509/x509.go
index d9288bb30e8..9ad3cf23f65 100644
--- a/libgo/go/crypto/x509/x509.go
+++ b/libgo/go/crypto/x509/x509.go
@@ -36,6 +36,12 @@ type pkixPublicKey struct {
 
 // ParsePKIXPublicKey parses a DER encoded public key. These values are
 // typically found in PEM blocks with "BEGIN PUBLIC KEY".
+//
+// Supported key types include RSA, DSA, and ECDSA. Unknown key
+// types result in an error.
+//
+// On success, pub will be of type *rsa.PublicKey, *dsa.PublicKey,
+// or *ecdsa.PublicKey.
 func ParsePKIXPublicKey(derBytes []byte) (pub interface{}, err error) {
 	var pki publicKeyInfo
 	if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
@@ -120,7 +126,7 @@ type certificate struct {
 
 type tbsCertificate struct {
 	Raw                asn1.RawContent
-	Version            int `asn1:"optional,explicit,default:1,tag:0"`
+	Version            int `asn1:"optional,explicit,default:0,tag:0"`
 	SerialNumber       *big.Int
 	SignatureAlgorithm pkix.AlgorithmIdentifier
 	Issuer             asn1.RawValue
@@ -264,7 +270,7 @@ var (
 	oidSignatureSHA384WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 12}
 	oidSignatureSHA512WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 13}
 	oidSignatureDSAWithSHA1     = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 3}
-	oidSignatureDSAWithSHA256   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 4, 3, 2}
+	oidSignatureDSAWithSHA256   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 3, 2}
 	oidSignatureECDSAWithSHA1   = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 1}
 	oidSignatureECDSAWithSHA256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 2}
 	oidSignatureECDSAWithSHA384 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 3}
@@ -635,7 +641,7 @@ var entrustBrokenSPKI = []byte{
 
 // CheckSignatureFrom verifies that the signature on c is a valid signature
 // from parent.
-func (c *Certificate) CheckSignatureFrom(parent *Certificate) (err error) {
+func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
 	// RFC 5280, 4.2.1.9:
 	// "If the basic constraints extension is not present in a version 3
 	// certificate, or the extension is present but the cA boolean is not
@@ -663,7 +669,7 @@ func (c *Certificate) CheckSignatureFrom(parent *Certificate) (err error) {
 
 // CheckSignature verifies that signature is a valid signature over signed from
 // c's public key.
-func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) (err error) {
+func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
 	return checkSignature(algo, signed, signature, c.PublicKey)
 }
 
@@ -731,7 +737,7 @@ func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey
 }
 
 // CheckCRLSignature checks that the signature in crl is from c.
-func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) (err error) {
+func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) error {
 	algo := getSignatureAlgorithmFromOID(crl.SignatureAlgorithm.Algorithm)
 	return c.CheckSignature(algo, crl.TBSCertList.Raw, crl.SignatureValue.RightAlign())
 }
@@ -1127,7 +1133,7 @@ func parseCertificate(in *certificate) (*Certificate, error) {
 				if rest, err := asn1.Unmarshal(e.Value, &keyid); err != nil {
 					return nil, err
 				} else if len(rest) != 0 {
-					return nil, errors.New("x509: trailing data after X.509 authority key-id")
+					return nil, errors.New("x509: trailing data after X.509 key-id")
 				}
 				out.SubjectKeyId = keyid
 
@@ -1581,21 +1587,21 @@ func CreateCertificate(rand io.Reader, template, parent *Certificate, pub, priv
 		return nil, err
 	}
 
-	if len(parent.SubjectKeyId) > 0 {
-		template.AuthorityKeyId = parent.SubjectKeyId
-	}
-
-	extensions, err := buildExtensions(template)
+	asn1Issuer, err := subjectBytes(parent)
 	if err != nil {
 		return
 	}
 
-	asn1Issuer, err := subjectBytes(parent)
+	asn1Subject, err := subjectBytes(template)
 	if err != nil {
 		return
 	}
 
-	asn1Subject, err := subjectBytes(template)
+	if !bytes.Equal(asn1Issuer, asn1Subject) && len(parent.SubjectKeyId) > 0 {
+		template.AuthorityKeyId = parent.SubjectKeyId
+	}
+
+	extensions, err := buildExtensions(template)
 	if err != nil {
 		return
 	}
@@ -1648,7 +1654,7 @@ var pemType = "X509 CRL"
 // encoded CRLs will appear where they should be DER encoded, so this function
 // will transparently handle PEM encoding as long as there isn't any leading
 // garbage.
-func ParseCRL(crlBytes []byte) (certList *pkix.CertificateList, err error) {
+func ParseCRL(crlBytes []byte) (*pkix.CertificateList, error) {
 	if bytes.HasPrefix(crlBytes, pemCRLPrefix) {
 		block, _ := pem.Decode(crlBytes)
 		if block != nil && block.Type == pemType {
@@ -1659,8 +1665,8 @@ func ParseCRL(crlBytes []byte) (certList *pkix.CertificateList, err error) {
 }
 
 // ParseDERCRL parses a DER encoded CRL from the given bytes.
-func ParseDERCRL(derBytes []byte) (certList *pkix.CertificateList, err error) {
-	certList = new(pkix.CertificateList)
+func ParseDERCRL(derBytes []byte) (*pkix.CertificateList, error) {
+	certList := new(pkix.CertificateList)
 	if rest, err := asn1.Unmarshal(derBytes, certList); err != nil {
 		return nil, err
 	} else if len(rest) != 0 {
@@ -1790,6 +1796,9 @@ var oidExtensionRequest = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 14}
 func newRawAttributes(attributes []pkix.AttributeTypeAndValueSET) ([]asn1.RawValue, error) {
 	var rawAttributes []asn1.RawValue
 	b, err := asn1.Marshal(attributes)
+	if err != nil {
+		return nil, err
+	}
 	rest, err := asn1.Unmarshal(b, &rawAttributes)
 	if err != nil {
 		return nil, err
@@ -1847,8 +1856,8 @@ func parseCSRExtensions(rawAttributes []asn1.RawValue) ([]pkix.Extension, error)
 	return ret, nil
 }
 
-// CreateCertificateRequest creates a new certificate based on a template. The
-// following members of template are used: Subject, Attributes,
+// CreateCertificateRequest creates a new certificate request based on a template.
+// The following members of template are used: Subject, Attributes,
 // SignatureAlgorithm, Extensions, DNSNames, EmailAddresses, and IPAddresses.
 // The private key is the private key of the signer.
 //
@@ -2065,7 +2074,7 @@ func parseCertificateRequest(in *certificateRequest) (*CertificateRequest, error
 	return out, nil
 }
 
-// CheckSignature verifies that the signature on c is a valid signature
-func (c *CertificateRequest) CheckSignature() (err error) {
+// CheckSignature reports whether the signature on c is valid.
+func (c *CertificateRequest) CheckSignature() error {
 	return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificateRequest, c.Signature, c.PublicKey)
 }
diff --git a/libgo/go/crypto/x509/x509_test.go b/libgo/go/crypto/x509/x509_test.go
index d1ef0274bc2..c6448d39ab5 100644
--- a/libgo/go/crypto/x509/x509_test.go
+++ b/libgo/go/crypto/x509/x509_test.go
@@ -96,6 +96,17 @@ tAboUGBxTDq3ZroNism3DaMIbKPyYrAqhKov1h5V
 -----END RSA PRIVATE KEY-----
 `
 
+var testPrivateKey *rsa.PrivateKey
+
+func init() {
+	block, _ := pem.Decode([]byte(pemPrivateKey))
+
+	var err error
+	if testPrivateKey, err = ParsePKCS1PrivateKey(block.Bytes); err != nil {
+		panic("Failed to parse private key: " + err.Error())
+	}
+}
+
 func bigFromString(s string) *big.Int {
 	ret := new(big.Int)
 	ret.SetString(s, 10)
@@ -314,12 +325,6 @@ var certBytes = "308203223082028ba00302010202106edf0d9499fd4533dd1297fc42a93be13
 func TestCreateSelfSignedCertificate(t *testing.T) {
 	random := rand.Reader
 
-	block, _ := pem.Decode([]byte(pemPrivateKey))
-	rsaPriv, err := ParsePKCS1PrivateKey(block.Bytes)
-	if err != nil {
-		t.Fatalf("Failed to parse private key: %s", err)
-	}
-
 	ecdsaPriv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
 	if err != nil {
 		t.Fatalf("Failed to generate ECDSA key: %s", err)
@@ -331,9 +336,9 @@ func TestCreateSelfSignedCertificate(t *testing.T) {
 		checkSig  bool
 		sigAlgo   SignatureAlgorithm
 	}{
-		{"RSA/RSA", &rsaPriv.PublicKey, rsaPriv, true, SHA1WithRSA},
-		{"RSA/ECDSA", &rsaPriv.PublicKey, ecdsaPriv, false, ECDSAWithSHA384},
-		{"ECDSA/RSA", &ecdsaPriv.PublicKey, rsaPriv, false, SHA256WithRSA},
+		{"RSA/RSA", &testPrivateKey.PublicKey, testPrivateKey, true, SHA1WithRSA},
+		{"RSA/ECDSA", &testPrivateKey.PublicKey, ecdsaPriv, false, ECDSAWithSHA384},
+		{"ECDSA/RSA", &ecdsaPriv.PublicKey, testPrivateKey, false, SHA256WithRSA},
 		{"ECDSA/ECDSA", &ecdsaPriv.PublicKey, ecdsaPriv, true, ECDSAWithSHA1},
 	}
 
@@ -488,7 +493,7 @@ func TestCreateSelfSignedCertificate(t *testing.T) {
 			t.Errorf("%s: ExtraExtensions didn't override SubjectKeyId", test.name)
 		}
 
-		if bytes.Index(derBytes, extraExtensionData) == -1 {
+		if !bytes.Contains(derBytes, extraExtensionData) {
 			t.Errorf("%s: didn't find extra extension in DER output", test.name)
 		}
 
@@ -874,12 +879,6 @@ const pemCRLBase64 = "LS0tLS1CRUdJTiBYNTA5IENSTC0tLS0tDQpNSUlCOWpDQ0FWOENBUUV3RF
 func TestCreateCertificateRequest(t *testing.T) {
 	random := rand.Reader
 
-	block, _ := pem.Decode([]byte(pemPrivateKey))
-	rsaPriv, err := ParsePKCS1PrivateKey(block.Bytes)
-	if err != nil {
-		t.Fatalf("Failed to parse private key: %s", err)
-	}
-
 	ecdsa256Priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
 	if err != nil {
 		t.Fatalf("Failed to generate ECDSA key: %s", err)
@@ -900,7 +899,7 @@ func TestCreateCertificateRequest(t *testing.T) {
 		priv    interface{}
 		sigAlgo SignatureAlgorithm
 	}{
-		{"RSA", rsaPriv, SHA1WithRSA},
+		{"RSA", testPrivateKey, SHA1WithRSA},
 		{"ECDSA-256", ecdsa256Priv, ECDSAWithSHA1},
 		{"ECDSA-384", ecdsa384Priv, ECDSAWithSHA1},
 		{"ECDSA-521", ecdsa521Priv, ECDSAWithSHA1},
@@ -951,13 +950,7 @@ func TestCreateCertificateRequest(t *testing.T) {
 }
 
 func marshalAndParseCSR(t *testing.T, template *CertificateRequest) *CertificateRequest {
-	block, _ := pem.Decode([]byte(pemPrivateKey))
-	rsaPriv, err := ParsePKCS1PrivateKey(block.Bytes)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	derBytes, err := CreateCertificateRequest(rand.Reader, template, rsaPriv)
+	derBytes, err := CreateCertificateRequest(rand.Reader, template, testPrivateKey)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1113,13 +1106,25 @@ func TestCriticalFlagInCSRRequestedExtensions(t *testing.T) {
 	}
 }
 
-func TestMaxPathLen(t *testing.T) {
-	block, _ := pem.Decode([]byte(pemPrivateKey))
-	rsaPriv, err := ParsePKCS1PrivateKey(block.Bytes)
+// serialiseAndParse generates a self-signed certificate from template and
+// returns a parsed version of it.
+func serialiseAndParse(t *testing.T, template *Certificate) *Certificate {
+	derBytes, err := CreateCertificate(rand.Reader, template, template, &testPrivateKey.PublicKey, testPrivateKey)
 	if err != nil {
-		t.Fatalf("Failed to parse private key: %s", err)
+		t.Fatalf("failed to create certificate: %s", err)
+		return nil
 	}
 
+	cert, err := ParseCertificate(derBytes)
+	if err != nil {
+		t.Fatalf("failed to parse certificate: %s", err)
+		return nil
+	}
+
+	return cert
+}
+
+func TestMaxPathLen(t *testing.T) {
 	template := &Certificate{
 		SerialNumber: big.NewInt(1),
 		Subject: pkix.Name{
@@ -1132,23 +1137,7 @@ func TestMaxPathLen(t *testing.T) {
 		IsCA: true,
 	}
 
-	serialiseAndParse := func(template *Certificate) *Certificate {
-		derBytes, err := CreateCertificate(rand.Reader, template, template, &rsaPriv.PublicKey, rsaPriv)
-		if err != nil {
-			t.Fatalf("failed to create certificate: %s", err)
-			return nil
-		}
-
-		cert, err := ParseCertificate(derBytes)
-		if err != nil {
-			t.Fatalf("failed to parse certificate: %s", err)
-			return nil
-		}
-
-		return cert
-	}
-
-	cert1 := serialiseAndParse(template)
+	cert1 := serialiseAndParse(t, template)
 	if m := cert1.MaxPathLen; m != -1 {
 		t.Errorf("Omitting MaxPathLen didn't turn into -1, got %d", m)
 	}
@@ -1157,7 +1146,7 @@ func TestMaxPathLen(t *testing.T) {
 	}
 
 	template.MaxPathLen = 1
-	cert2 := serialiseAndParse(template)
+	cert2 := serialiseAndParse(t, template)
 	if m := cert2.MaxPathLen; m != 1 {
 		t.Errorf("Setting MaxPathLen didn't work. Got %d but set 1", m)
 	}
@@ -1167,7 +1156,7 @@ func TestMaxPathLen(t *testing.T) {
 
 	template.MaxPathLen = 0
 	template.MaxPathLenZero = true
-	cert3 := serialiseAndParse(template)
+	cert3 := serialiseAndParse(t, template)
 	if m := cert3.MaxPathLen; m != 0 {
 		t.Errorf("Setting MaxPathLenZero didn't work, got %d", m)
 	}
@@ -1176,6 +1165,30 @@ func TestMaxPathLen(t *testing.T) {
 	}
 }
 
+func TestNoAuthorityKeyIdInSelfSignedCert(t *testing.T) {
+	template := &Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject: pkix.Name{
+			CommonName: "Σ Acme Co",
+		},
+		NotBefore: time.Unix(1000, 0),
+		NotAfter:  time.Unix(100000, 0),
+
+		BasicConstraintsValid: true,
+		IsCA:         true,
+		SubjectKeyId: []byte{1, 2, 3, 4},
+	}
+
+	if cert := serialiseAndParse(t, template); len(cert.AuthorityKeyId) != 0 {
+		t.Fatalf("self-signed certificate contained default authority key id")
+	}
+
+	template.AuthorityKeyId = []byte{1, 2, 3, 4}
+	if cert := serialiseAndParse(t, template); len(cert.AuthorityKeyId) == 0 {
+		t.Fatalf("self-signed certificate erased explicit authority key id")
+	}
+}
+
 func TestASN1BitLength(t *testing.T) {
 	tests := []struct {
 		bytes  []byte
diff --git a/libgo/go/database/sql/convert.go b/libgo/go/database/sql/convert.go
index 740fd9d6e7c..99aed2398e2 100644
--- a/libgo/go/database/sql/convert.go
+++ b/libgo/go/database/sql/convert.go
@@ -44,7 +44,7 @@ func driverArgs(ds *driverStmt, args []interface{}) ([]driver.Value, error) {
 	// Let the Stmt convert its own arguments.
 	for n, arg := range args {
 		// First, see if the value itself knows how to convert
-		// itself to a driver type.  For example, a NullString
+		// itself to a driver type. For example, a NullString
 		// struct changing into a string or nil.
 		if svi, ok := arg.(driver.Valuer); ok {
 			sv, err := svi.Value()
@@ -217,7 +217,12 @@ func convertAssign(dest, src interface{}) error {
 
 	dv := reflect.Indirect(dpv)
 	if sv.IsValid() && sv.Type().AssignableTo(dv.Type()) {
-		dv.Set(sv)
+		switch b := src.(type) {
+		case []byte:
+			dv.Set(reflect.ValueOf(cloneBytes(b)))
+		default:
+			dv.Set(sv)
+		}
 		return nil
 	}
 
diff --git a/libgo/go/database/sql/convert_test.go b/libgo/go/database/sql/convert_test.go
index 342875e190c..ab81f2f65a2 100644
--- a/libgo/go/database/sql/convert_test.go
+++ b/libgo/go/database/sql/convert_test.go
@@ -377,3 +377,15 @@ func TestRawBytesAllocs(t *testing.T) {
 		t.Fatalf("allocs = %v; want max 1", n)
 	}
 }
+
+// https://github.com/golang/go/issues/13905
+func TestUserDefinedBytes(t *testing.T) {
+	type userDefinedBytes []byte
+	var u userDefinedBytes
+	v := []byte("foo")
+
+	convertAssign(&u, v)
+	if &u[0] == &v[0] {
+		t.Fatal("userDefinedBytes got potentially dirty driver memory")
+	}
+}
diff --git a/libgo/go/database/sql/driver/driver.go b/libgo/go/database/sql/driver/driver.go
index eca25f29a0a..4dba85a6d34 100644
--- a/libgo/go/database/sql/driver/driver.go
+++ b/libgo/go/database/sql/driver/driver.go
@@ -17,7 +17,7 @@ import "errors"
 //   float64
 //   bool
 //   []byte
-//   string   [*] everywhere except from Rows.Next.
+//   string
 //   time.Time
 type Value interface{}
 
@@ -144,7 +144,7 @@ type Stmt interface {
 // any type to a driver Value.
 type ColumnConverter interface {
 	// ColumnConverter returns a ValueConverter for the provided
-	// column index.  If the type of a specific column isn't known
+	// column index. If the type of a specific column isn't known
 	// or shouldn't be handled specially, DefaultValueConverter
 	// can be returned.
 	ColumnConverter(idx int) ValueConverter
@@ -154,7 +154,7 @@ type ColumnConverter interface {
 type Rows interface {
 	// Columns returns the names of the columns. The number of
 	// columns of the result is inferred from the length of the
-	// slice.  If a particular column name isn't known, an empty
+	// slice. If a particular column name isn't known, an empty
 	// string should be returned for that entry.
 	Columns() []string
 
@@ -165,10 +165,6 @@ type Rows interface {
 	// the provided slice. The provided slice will be the same
 	// size as the Columns() are wide.
 	//
-	// The dest slice may be populated only with
-	// a driver Value type, but excluding string.
-	// All string values must be converted to []byte.
-	//
 	// Next should return io.EOF when there are no more rows.
 	Next(dest []Value) error
 }
diff --git a/libgo/go/database/sql/driver/types.go b/libgo/go/database/sql/driver/types.go
index bc547849897..e480e701a49 100644
--- a/libgo/go/database/sql/driver/types.go
+++ b/libgo/go/database/sql/driver/types.go
@@ -15,7 +15,7 @@ import (
 //
 // Various implementations of ValueConverter are provided by the
 // driver package to provide consistent implementations of conversions
-// between drivers.  The ValueConverters have several uses:
+// between drivers. The ValueConverters have several uses:
 //
 //  * converting from the Value types as provided by the sql package
 //    into a database table's specific column type and making sure it
@@ -172,28 +172,21 @@ func (n NotNull) ConvertValue(v interface{}) (Value, error) {
 }
 
 // IsValue reports whether v is a valid Value parameter type.
-// Unlike IsScanValue, IsValue permits the string type.
 func IsValue(v interface{}) bool {
-	if IsScanValue(v) {
+	if v == nil {
 		return true
 	}
-	if _, ok := v.(string); ok {
+	switch v.(type) {
+	case []byte, bool, float64, int64, string, time.Time:
 		return true
 	}
 	return false
 }
 
-// IsScanValue reports whether v is a valid Value scan type.
-// Unlike IsValue, IsScanValue does not permit the string type.
+// IsScanValue is equivalent to IsValue.
+// It exists for compatibility.
 func IsScanValue(v interface{}) bool {
-	if v == nil {
-		return true
-	}
-	switch v.(type) {
-	case int64, float64, []byte, bool, time.Time:
-		return true
-	}
-	return false
+	return IsValue(v)
 }
 
 // DefaultParameterConverter is the default implementation of
diff --git a/libgo/go/database/sql/fakedb_test.go b/libgo/go/database/sql/fakedb_test.go
index b5ff1213587..5b238bfc5cb 100644
--- a/libgo/go/database/sql/fakedb_test.go
+++ b/libgo/go/database/sql/fakedb_test.go
@@ -37,7 +37,7 @@ var _ = log.Printf
 // named method on fakeStmt to panic.
 //
 // When opening a fakeDriver's database, it starts empty with no
-// tables.  All tables and data are stored in memory only.
+// tables. All tables and data are stored in memory only.
 type fakeDriver struct {
 	mu         sync.Mutex // guards 3 following fields
 	openCount  int        // conn opens
@@ -51,7 +51,6 @@ type fakeDB struct {
 	name string
 
 	mu      sync.Mutex
-	free    []*fakeConn
 	tables  map[string]*table
 	badConn bool
 }
@@ -76,12 +75,6 @@ type row struct {
 	cols []interface{} // must be same size as its table colname + coltype
 }
 
-func (r *row) clone() *row {
-	nrow := &row{cols: make([]interface{}, len(r.cols))}
-	copy(nrow.cols, r.cols)
-	return nrow
-}
-
 type fakeConn struct {
 	db *fakeDB // where to return ourselves to
 
@@ -705,7 +698,7 @@ func (s *fakeStmt) Query(args []driver.Value) (driver.Rows, error) {
 rows:
 	for _, trow := range t.rows {
 		// Process the where clause, skipping non-match rows. This is lazy
-		// and just uses fmt.Sprintf("%v") to test equality.  Good enough
+		// and just uses fmt.Sprintf("%v") to test equality. Good enough
 		// for test code.
 		for widx, wcol := range s.whereCol {
 			idx := t.columnIndex(wcol)
diff --git a/libgo/go/database/sql/sql.go b/libgo/go/database/sql/sql.go
index d8e7cb77af3..09de1c34e82 100644
--- a/libgo/go/database/sql/sql.go
+++ b/libgo/go/database/sql/sql.go
@@ -199,7 +199,7 @@ type Scanner interface {
 	//    time.Time
 	//    nil - for NULL values
 	//
-	// An error should be returned if the value can not be stored
+	// An error should be returned if the value cannot be stored
 	// without loss of information.
 	Scan(src interface{}) error
 }
@@ -718,6 +718,9 @@ func (db *DB) maybeOpenNewConnections() {
 	for numRequests > 0 {
 		db.numOpen++ // optimistically
 		numRequests--
+		if db.closed {
+			return
+		}
 		db.openerCh <- struct{}{}
 	}
 }
@@ -797,7 +800,7 @@ func (db *DB) conn(strategy connReuseStrategy) (*driverConn, error) {
 		return conn, nil
 	}
 
-	// Out of free connections or we were asked not to use one.  If we're not
+	// Out of free connections or we were asked not to use one. If we're not
 	// allowed to open any more connections, make a request and wait.
 	if db.maxOpen > 0 && db.numOpen >= db.maxOpen {
 		// Make the connRequest channel. It's buffered so that the
@@ -838,11 +841,6 @@ func (db *DB) conn(strategy connReuseStrategy) (*driverConn, error) {
 	return dc, nil
 }
 
-var (
-	errConnClosed = errors.New("database/sql: internal sentinel error: conn is closed")
-	errConnBusy   = errors.New("database/sql: internal sentinel error: conn is busy")
-)
-
 // putConnHook is a hook for testing.
 var putConnHook func(*DB, *driverConn)
 
@@ -920,6 +918,9 @@ func (db *DB) putConn(dc *driverConn, err error) {
 // If a connRequest was fulfilled or the *driverConn was placed in the
 // freeConn list, then true is returned, otherwise false is returned.
 func (db *DB) putConnDBLocked(dc *driverConn, err error) bool {
+	if db.closed {
+		return false
+	}
 	if db.maxOpen > 0 && db.numOpen > db.maxOpen {
 		return false
 	}
@@ -1207,7 +1208,7 @@ type Tx struct {
 	// ErrTxDone.
 	done bool
 
-	// All Stmts prepared for this transaction.  These will be closed after the
+	// All Stmts prepared for this transaction. These will be closed after the
 	// transaction has been committed or rolled back.
 	stmts struct {
 		sync.Mutex
@@ -1286,7 +1287,7 @@ func (tx *Tx) Prepare(query string) (*Stmt, error) {
 	// necessary. Or, better: keep a map in DB of query string to
 	// Stmts, and have Stmt.Execute do the right thing and
 	// re-prepare if the Conn in use doesn't have that prepared
-	// statement.  But we'll want to avoid caching the statement
+	// statement. But we'll want to avoid caching the statement
 	// in the case where we only call conn.Prepare implicitly
 	// (such as in db.Exec or tx.Exec), but the caller package
 	// can't be holding a reference to the returned statement.
@@ -1334,7 +1335,7 @@ func (tx *Tx) Prepare(query string) (*Stmt, error) {
 // be used once the transaction has been committed or rolled back.
 func (tx *Tx) Stmt(stmt *Stmt) *Stmt {
 	// TODO(bradfitz): optimize this. Currently this re-prepares
-	// each time.  This is fine for now to illustrate the API but
+	// each time. This is fine for now to illustrate the API but
 	// we should really cache already-prepared statements
 	// per-Conn. See also the big comment in Tx.Prepare.
 
@@ -1441,9 +1442,9 @@ type Stmt struct {
 	closed bool
 
 	// css is a list of underlying driver statement interfaces
-	// that are valid on particular connections.  This is only
+	// that are valid on particular connections. This is only
 	// used if tx == nil and one is found that has idle
-	// connections.  If tx != nil, txsi is always used.
+	// connections. If tx != nil, txsi is always used.
 	css []connStmt
 
 	// lastNumClosed is copied from db.numClosed when Stmt is created
@@ -1741,9 +1742,9 @@ type Rows struct {
 	closeStmt driver.Stmt // if non-nil, statement to Close on close
 }
 
-// Next prepares the next result row for reading with the Scan method.  It
+// Next prepares the next result row for reading with the Scan method. It
 // returns true on success, or false if there is no next result row or an error
-// happened while preparing it.  Err should be consulted to distinguish between
+// happened while preparing it. Err should be consulted to distinguish between
 // the two cases.
 //
 // Every call to Scan, even the first one, must be preceded by a call to Next.
@@ -1898,8 +1899,8 @@ func (r *Row) Scan(dest ...interface{}) error {
 	// the Rows in our defer, when we return from this function.
 	// the contract with the driver.Next(...) interface is that it
 	// can return slices into read-only temporary memory that's
-	// only valid until the next Scan/Close.  But the TODO is that
-	// for a lot of drivers, this copy will be unnecessary.  We
+	// only valid until the next Scan/Close. But the TODO is that
+	// for a lot of drivers, this copy will be unnecessary. We
 	// should provide an optional interface for drivers to
 	// implement to say, "don't worry, the []bytes that I return
 	// from Next will not be modified again." (for instance, if
diff --git a/libgo/go/database/sql/sql_test.go b/libgo/go/database/sql/sql_test.go
index 8ec70d99b02..08df0c7666a 100644
--- a/libgo/go/database/sql/sql_test.go
+++ b/libgo/go/database/sql/sql_test.go
@@ -144,7 +144,7 @@ func closeDB(t testing.TB, db *DB) {
 	count := db.numOpen
 	db.mu.Unlock()
 	if count != 0 {
-		t.Fatalf("%d connections still open after closing DB", db.numOpen)
+		t.Fatalf("%d connections still open after closing DB", count)
 	}
 }
 
@@ -911,7 +911,7 @@ func nullTestRun(t *testing.T, spec nullTestSpec) {
 	if err == nil {
 		// TODO: this test fails, but it's just because
 		// fakeConn implements the optional Execer interface,
-		// so arguably this is the correct behavior.  But
+		// so arguably this is the correct behavior. But
 		// maybe I should flesh out the fakeConn.Exec
 		// implementation so this properly fails.
 		// t.Errorf("expected error inserting nil name with Exec")
@@ -1239,7 +1239,7 @@ func TestPendingConnsAfterErr(t *testing.T) {
 	time.Sleep(10 * time.Millisecond) // make extra sure all workers are blocked
 	close(unblock)                    // let all workers proceed
 
-	const timeout = 100 * time.Millisecond
+	const timeout = 5 * time.Second
 	to := time.NewTimer(timeout)
 	defer to.Stop()
 
@@ -1591,7 +1591,7 @@ func TestStmtCloseOrder(t *testing.T) {
 
 	_, err := db.Query("SELECT|non_existent|name|")
 	if err == nil {
-		t.Fatal("Quering non-existent table should fail")
+		t.Fatal("Querying non-existent table should fail")
 	}
 }
 
@@ -1615,6 +1615,8 @@ func TestManyErrBadConn(t *testing.T) {
 			}
 		}()
 
+		db.mu.Lock()
+		defer db.mu.Unlock()
 		if db.numOpen != nconn {
 			t.Fatalf("unexpected numOpen %d (was expecting %d)", db.numOpen, nconn)
 		} else if len(db.freeConn) != nconn {
diff --git a/libgo/go/debug/dwarf/buf.go b/libgo/go/debug/dwarf/buf.go
index 2ade0bd76ad..24d266db107 100644
--- a/libgo/go/debug/dwarf/buf.go
+++ b/libgo/go/debug/dwarf/buf.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -22,16 +22,16 @@ type buf struct {
 	err    error
 }
 
-// Data format, other than byte order.  This affects the handling of
+// Data format, other than byte order. This affects the handling of
 // certain field formats.
 type dataFormat interface {
-	// DWARF version number.  Zero means unknown.
+	// DWARF version number. Zero means unknown.
 	version() int
 
 	// 64-bit DWARF format?
 	dwarf64() (dwarf64 bool, isKnown bool)
 
-	// Size of an address, in bytes.  Zero means unknown.
+	// Size of an address, in bytes. Zero means unknown.
 	addrsize() int
 }
 
@@ -157,7 +157,7 @@ func (b *buf) addr() uint64 {
 	case 4:
 		return uint64(b.uint32())
 	case 8:
-		return uint64(b.uint64())
+		return b.uint64()
 	}
 	b.error("unknown address size")
 	return 0
diff --git a/libgo/go/debug/dwarf/const.go b/libgo/go/debug/dwarf/const.go
index 2170db1e32d..04d8c506b06 100644
--- a/libgo/go/debug/dwarf/const.go
+++ b/libgo/go/debug/dwarf/const.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/dwarf/entry.go b/libgo/go/debug/dwarf/entry.go
index 5ca86679fa5..80bf14cb22f 100644
--- a/libgo/go/debug/dwarf/entry.go
+++ b/libgo/go/debug/dwarf/entry.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -243,7 +243,7 @@ type Field struct {
 	Class Class
 }
 
-// A Class is the DWARF 4 class of an attibute value.
+// A Class is the DWARF 4 class of an attribute value.
 //
 // In general, a given attribute's value may take on one of several
 // possible classes defined by DWARF, each of which leads to a
@@ -506,7 +506,7 @@ func (b *buf) entry(atab abbrevTable, ubase Offset) *Entry {
 }
 
 // A Reader allows reading Entry structures from a DWARF ``info'' section.
-// The Entry structures are arranged in a tree.  The Reader's Next function
+// The Entry structures are arranged in a tree. The Reader's Next function
 // return successive entries from a pre-order traversal of the tree.
 // If an entry has children, its Children field will be true, and the children
 // follow, terminated by an Entry with Tag 0.
@@ -598,7 +598,7 @@ func (r *Reader) Next() (*Entry, error) {
 }
 
 // SkipChildren skips over the child entries associated with
-// the last Entry returned by Next.  If that Entry did not have
+// the last Entry returned by Next. If that Entry did not have
 // children or Next has not been called, SkipChildren is a no-op.
 func (r *Reader) SkipChildren() {
 	if r.err != nil || !r.lastChildren {
@@ -625,14 +625,134 @@ func (r *Reader) SkipChildren() {
 	}
 }
 
-// clone returns a copy of the reader.  This is used by the typeReader
+// clone returns a copy of the reader. This is used by the typeReader
 // interface.
 func (r *Reader) clone() typeReader {
 	return r.d.Reader()
 }
 
-// offset returns the current buffer offset.  This is used by the
+// offset returns the current buffer offset. This is used by the
 // typeReader interface.
 func (r *Reader) offset() Offset {
 	return r.b.off
 }
+
+// SeekPC returns the Entry for the compilation unit that includes pc,
+// and positions the reader to read the children of that unit.  If pc
+// is not covered by any unit, SeekPC returns ErrUnknownPC and the
+// position of the reader is undefined.
+//
+// Because compilation units can describe multiple regions of the
+// executable, in the worst case SeekPC must search through all the
+// ranges in all the compilation units. Each call to SeekPC starts the
+// search at the compilation unit of the last call, so in general
+// looking up a series of PCs will be faster if they are sorted. If
+// the caller wishes to do repeated fast PC lookups, it should build
+// an appropriate index using the Ranges method.
+func (r *Reader) SeekPC(pc uint64) (*Entry, error) {
+	unit := r.unit
+	for i := 0; i < len(r.d.unit); i++ {
+		if unit >= len(r.d.unit) {
+			unit = 0
+		}
+		r.err = nil
+		r.lastChildren = false
+		r.unit = unit
+		u := &r.d.unit[unit]
+		r.b = makeBuf(r.d, u, "info", u.off, u.data)
+		e, err := r.Next()
+		if err != nil {
+			return nil, err
+		}
+		ranges, err := r.d.Ranges(e)
+		if err != nil {
+			return nil, err
+		}
+		for _, pcs := range ranges {
+			if pcs[0] <= pc && pc < pcs[1] {
+				return e, nil
+			}
+		}
+		unit++
+	}
+	return nil, ErrUnknownPC
+}
+
+// Ranges returns the PC ranges covered by e, a slice of [low,high) pairs.
+// Only some entry types, such as TagCompileUnit or TagSubprogram, have PC
+// ranges; for others, this will return nil with no error.
+func (d *Data) Ranges(e *Entry) ([][2]uint64, error) {
+	var ret [][2]uint64
+
+	low, lowOK := e.Val(AttrLowpc).(uint64)
+
+	var high uint64
+	var highOK bool
+	highField := e.AttrField(AttrHighpc)
+	if highField != nil {
+		switch highField.Class {
+		case ClassAddress:
+			high, highOK = highField.Val.(uint64)
+		case ClassConstant:
+			off, ok := highField.Val.(int64)
+			if ok {
+				high = low + uint64(off)
+				highOK = true
+			}
+		}
+	}
+
+	if lowOK && highOK {
+		ret = append(ret, [2]uint64{low, high})
+	}
+
+	ranges, rangesOK := e.Val(AttrRanges).(int64)
+	if rangesOK && d.ranges != nil {
+		// The initial base address is the lowpc attribute
+		// of the enclosing compilation unit.
+		// Although DWARF specifies the lowpc attribute,
+		// comments in gdb/dwarf2read.c say that some versions
+		// of GCC use the entrypc attribute, so we check that too.
+		var cu *Entry
+		if e.Tag == TagCompileUnit {
+			cu = e
+		} else {
+			i := d.offsetToUnit(e.Offset)
+			if i == -1 {
+				return nil, errors.New("no unit for entry")
+			}
+			u := &d.unit[i]
+			b := makeBuf(d, u, "info", u.off, u.data)
+			cu = b.entry(u.atable, u.base)
+			if b.err != nil {
+				return nil, b.err
+			}
+		}
+
+		var base uint64
+		if cuEntry, cuEntryOK := cu.Val(AttrEntrypc).(uint64); cuEntryOK {
+			base = cuEntry
+		} else if cuLow, cuLowOK := cu.Val(AttrLowpc).(uint64); cuLowOK {
+			base = cuLow
+		}
+
+		u := &d.unit[d.offsetToUnit(e.Offset)]
+		buf := makeBuf(d, u, "ranges", Offset(ranges), d.ranges[ranges:])
+		for len(buf.data) > 0 {
+			low = buf.addr()
+			high = buf.addr()
+
+			if low == 0 && high == 0 {
+				break
+			}
+
+			if low == ^uint64(0)>>uint((8-u.addrsize())*8) {
+				base = high
+			} else {
+				ret = append(ret, [2]uint64{base + low, base + high})
+			}
+		}
+	}
+
+	return ret, nil
+}
diff --git a/libgo/go/debug/dwarf/entry_test.go b/libgo/go/debug/dwarf/entry_test.go
index 8bd2d2a8ad4..58a5d570be5 100644
--- a/libgo/go/debug/dwarf/entry_test.go
+++ b/libgo/go/debug/dwarf/entry_test.go
@@ -6,6 +6,7 @@ package dwarf_test
 
 import (
 	. "debug/dwarf"
+	"reflect"
 	"testing"
 )
 
@@ -34,3 +35,103 @@ func TestSplit(t *testing.T) {
 		t.Fatalf("bad class: have %s, want %s", f.Class, ClassUnknown)
 	}
 }
+
+// wantRange maps from a PC to the ranges of the compilation unit
+// containing that PC.
+type wantRange struct {
+	pc     uint64
+	ranges [][2]uint64
+}
+
+func TestReaderSeek(t *testing.T) {
+	want := []wantRange{
+		{0x40059d, [][2]uint64{{0x40059d, 0x400601}}},
+		{0x400600, [][2]uint64{{0x40059d, 0x400601}}},
+		{0x400601, [][2]uint64{{0x400601, 0x400611}}},
+		{0x4005f0, [][2]uint64{{0x40059d, 0x400601}}}, // loop test
+		{0x10, nil},
+		{0x400611, nil},
+	}
+	testRanges(t, "testdata/line-gcc.elf", want)
+}
+
+func TestRangesSection(t *testing.T) {
+	want := []wantRange{
+		{0x400500, [][2]uint64{{0x400500, 0x400549}, {0x400400, 0x400408}}},
+		{0x400400, [][2]uint64{{0x400500, 0x400549}, {0x400400, 0x400408}}},
+		{0x400548, [][2]uint64{{0x400500, 0x400549}, {0x400400, 0x400408}}},
+		{0x400407, [][2]uint64{{0x400500, 0x400549}, {0x400400, 0x400408}}},
+		{0x400408, nil},
+		{0x400449, nil},
+		{0x4003ff, nil},
+	}
+	testRanges(t, "testdata/ranges.elf", want)
+}
+
+func testRanges(t *testing.T, name string, want []wantRange) {
+	d := elfData(t, name)
+	r := d.Reader()
+	for _, w := range want {
+		entry, err := r.SeekPC(w.pc)
+		if err != nil {
+			if w.ranges != nil {
+				t.Errorf("%s: missing Entry for %#x", name, w.pc)
+			}
+			if err != ErrUnknownPC {
+				t.Errorf("%s: expected ErrUnknownPC for %#x, got %v", name, w.pc, err)
+			}
+			continue
+		}
+
+		ranges, err := d.Ranges(entry)
+		if err != nil {
+			t.Errorf("%s: %v", name, err)
+			continue
+		}
+		if !reflect.DeepEqual(ranges, w.ranges) {
+			t.Errorf("%s: for %#x got %x, expected %x", name, w.pc, ranges, w.ranges)
+		}
+	}
+}
+
+func TestReaderRanges(t *testing.T) {
+	d := elfData(t, "testdata/line-gcc.elf")
+
+	subprograms := []struct {
+		name   string
+		ranges [][2]uint64
+	}{
+		{"f1", [][2]uint64{{0x40059d, 0x4005e7}}},
+		{"main", [][2]uint64{{0x4005e7, 0x400601}}},
+		{"f2", [][2]uint64{{0x400601, 0x400611}}},
+	}
+
+	r := d.Reader()
+	i := 0
+	for entry, err := r.Next(); entry != nil && err == nil; entry, err = r.Next() {
+		if entry.Tag != TagSubprogram {
+			continue
+		}
+
+		if i > len(subprograms) {
+			t.Fatalf("too many subprograms (expected at most %d)", i)
+		}
+
+		if got := entry.Val(AttrName).(string); got != subprograms[i].name {
+			t.Errorf("subprogram %d name is %s, expected %s", i, got, subprograms[i].name)
+		}
+		ranges, err := d.Ranges(entry)
+		if err != nil {
+			t.Errorf("subprogram %d: %v", i, err)
+			continue
+		}
+		if !reflect.DeepEqual(ranges, subprograms[i].ranges) {
+			t.Errorf("subprogram %d ranges are %x, expected %x", i, ranges, subprograms[i].ranges)
+		}
+		i++
+	}
+
+	if i < len(subprograms) {
+		t.Errorf("saw only %d subprograms, expected %d", i, len(subprograms))
+	}
+}
diff --git a/libgo/go/debug/dwarf/line.go b/libgo/go/debug/dwarf/line.go
index ca64bbd7f3b..ed82feef92b 100644
--- a/libgo/go/debug/dwarf/line.go
+++ b/libgo/go/debug/dwarf/line.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -361,7 +361,7 @@ func (r *LineReader) step(entry *LineEntry) bool {
 		// Special opcode [DWARF2 6.2.5.1, DWARF4 6.2.5.1]
 		adjustedOpcode := opcode - r.opcodeBase
 		r.advancePC(adjustedOpcode / r.lineRange)
-		lineDelta := r.lineBase + int(adjustedOpcode)%r.lineRange
+		lineDelta := r.lineBase + adjustedOpcode%r.lineRange
 		r.state.Line += lineDelta
 		goto emit
 	}
diff --git a/libgo/go/debug/dwarf/line_test.go b/libgo/go/debug/dwarf/line_test.go
index 4104b5d49b8..cc363f54785 100644
--- a/libgo/go/debug/dwarf/line_test.go
+++ b/libgo/go/debug/dwarf/line_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/dwarf/open.go b/libgo/go/debug/dwarf/open.go
index c1b3f37aca9..0e9c01c2e98 100644
--- a/libgo/go/debug/dwarf/open.go
+++ b/libgo/go/debug/dwarf/open.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -78,9 +78,9 @@ func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Dat
 	return d, nil
 }
 
-// AddTypes will add one .debug_types section to the DWARF data.  A
+// AddTypes will add one .debug_types section to the DWARF data. A
 // typical object with DWARF version 4 debug info will have multiple
-// .debug_types sections.  The name is used for error reporting only,
+// .debug_types sections. The name is used for error reporting only,
 // and serves to distinguish one .debug_types section from another.
 func (d *Data) AddTypes(name string, types []byte) error {
 	return d.parseTypes(name, types)
diff --git a/libgo/go/debug/dwarf/testdata/ranges.c b/libgo/go/debug/dwarf/testdata/ranges.c
new file mode 100644
index 00000000000..2f208e591c7
--- /dev/null
+++ b/libgo/go/debug/dwarf/testdata/ranges.c
@@ -0,0 +1,25 @@
+// gcc -g -O2 -freorder-blocks-and-partition
+
+const char *arr[10000];
+const char *hot = "hot";
+const char *cold = "cold";
+
+__attribute__((noinline))
+void fn(int path) {
+	int i;
+
+	if (path) {
+		for (i = 0; i < sizeof arr / sizeof arr[0]; i++) {
+			arr[i] = hot;
+		}
+	} else {
+		for (i = 0; i < sizeof arr / sizeof arr[0]; i++) {
+			arr[i] = cold;
+		}
+	}
+}
+
+int main(int argc, char *argv[]) {
+	fn(argc);
+	return 0;
+}
diff --git a/libgo/go/debug/dwarf/testdata/ranges.elf b/libgo/go/debug/dwarf/testdata/ranges.elf
new file mode 100644
index 00000000000..7f54138cffb
--- /dev/null
+++ b/libgo/go/debug/dwarf/testdata/ranges.elf
diff --git a/libgo/go/debug/dwarf/testdata/typedef.c b/libgo/go/debug/dwarf/testdata/typedef.c
index f05f01564ff..4780a0b2bad 100644
--- a/libgo/go/debug/dwarf/testdata/typedef.c
+++ b/libgo/go/debug/dwarf/testdata/typedef.c
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/dwarf/type.go b/libgo/go/debug/dwarf/type.go
index c76a472d78c..9b39078a6fb 100644
--- a/libgo/go/debug/dwarf/type.go
+++ b/libgo/go/debug/dwarf/type.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -356,7 +356,7 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 	}
 
 	// Get Type referred to by Entry's AttrType field.
-	// Set err if error happens.  Not having a type is an error.
+	// Set err if error happens. Not having a type is an error.
 	typeOf := func(e *Entry) Type {
 		tval := e.Val(AttrType)
 		var t Type
@@ -549,7 +549,7 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 					bito = f.ByteOffset * 8
 				}
 				if bito == lastFieldBitOffset && t.Kind != "union" {
-					// Last field was zero width.  Fix array length.
+					// Last field was zero width. Fix array length.
 					// (DWARF writes out 0-length arrays as if they were 1-length arrays.)
 					zeroArray(lastFieldType)
 				}
@@ -560,7 +560,7 @@ func (d *Data) readType(name string, r typeReader, off Offset, typeCache map[Off
 		if t.Kind != "union" {
 			b, ok := e.Val(AttrByteSize).(int64)
 			if ok && b*8 == lastFieldBitOffset {
-				// Final field must be zero width.  Fix array length.
+				// Final field must be zero width. Fix array length.
 				zeroArray(lastFieldType)
 			}
 		}
diff --git a/libgo/go/debug/dwarf/type_test.go b/libgo/go/debug/dwarf/type_test.go
index ad6308deba0..0283466f088 100644
--- a/libgo/go/debug/dwarf/type_test.go
+++ b/libgo/go/debug/dwarf/type_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -34,7 +34,7 @@ var typedefTests = map[string]string{
 }
 
 // As Apple converts gcc to a clang-based front end
-// they keep breaking the DWARF output.  This map lists the
+// they keep breaking the DWARF output. This map lists the
 // conversion from real answer to Apple answer.
 var machoBug = map[string]string{
 	"func(*char, ...) void":                                 "func(*char) void",
diff --git a/libgo/go/debug/dwarf/typeunit.go b/libgo/go/debug/dwarf/typeunit.go
index 0f4e07ebf7c..652e02d9172 100644
--- a/libgo/go/debug/dwarf/typeunit.go
+++ b/libgo/go/debug/dwarf/typeunit.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -9,11 +9,11 @@ import (
 	"strconv"
 )
 
-// Parse the type units stored in a DWARF4 .debug_types section.  Each
+// Parse the type units stored in a DWARF4 .debug_types section. Each
 // type unit defines a single primary type and an 8-byte signature.
 // Other sections may then use formRefSig8 to refer to the type.
 
-// The typeUnit format is a single type with a signature.  It holds
+// The typeUnit format is a single type with a signature. It holds
 // the same data as a compilation unit.
 type typeUnit struct {
 	unit
@@ -76,7 +76,7 @@ func (d *Data) parseTypes(name string, types []byte) error {
 				data:   b.bytes(int(n - (b.off - hdroff))),
 				atable: atable,
 				asize:  int(asize),
-				vers:   int(vers),
+				vers:   vers,
 				is64:   dwarf64,
 			},
 			toff: Offset(toff),
@@ -101,7 +101,7 @@ func (d *Data) sigToType(sig uint64) (Type, error) {
 
 	b := makeBuf(d, tu, tu.name, tu.off, tu.data)
 	r := &typeUnitReader{d: d, tu: tu, b: b}
-	t, err := d.readType(tu.name, r, Offset(tu.toff), make(map[Offset]Type), nil)
+	t, err := d.readType(tu.name, r, tu.toff, make(map[Offset]Type), nil)
 	if err != nil {
 		return nil, err
 	}
diff --git a/libgo/go/debug/dwarf/unit.go b/libgo/go/debug/dwarf/unit.go
index ceb6cdbff32..e45aed7ad1d 100644
--- a/libgo/go/debug/dwarf/unit.go
+++ b/libgo/go/debug/dwarf/unit.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/elf/elf.go b/libgo/go/debug/elf/elf.go
index 6086b54b9f2..6e6c801a49a 100644
--- a/libgo/go/debug/elf/elf.go
+++ b/libgo/go/debug/elf/elf.go
@@ -15,7 +15,7 @@
  *
  * Copyright (c) 1996-1998 John D. Polstra.  All rights reserved.
  * Copyright (c) 2001 David E. O'Brien
- * Portions Copyright 2009 The Go Authors.  All rights reserved.
+ * Portions Copyright 2009 The Go Authors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -1285,7 +1285,7 @@ const (
 	R_MIPS_LITERAL       R_MIPS = 8  /* Reference to literal section  */
 	R_MIPS_GOT16         R_MIPS = 9  /* Reference to global offset table */
 	R_MIPS_PC16          R_MIPS = 10 /* 16 bit PC relative reference */
-	R_MIPS_CALL16        R_MIPS = 11 /* 16 bit call thru glbl offset tbl */
+	R_MIPS_CALL16        R_MIPS = 11 /* 16 bit call through glbl offset tbl */
 	R_MIPS_GPREL32       R_MIPS = 12
 	R_MIPS_SHIFT5        R_MIPS = 16
 	R_MIPS_SHIFT6        R_MIPS = 17
@@ -1725,37 +1725,71 @@ var rppc64Strings = []intName{
 func (i R_PPC64) String() string   { return stringName(uint32(i), rppc64Strings, false) }
 func (i R_PPC64) GoString() string { return stringName(uint32(i), rppc64Strings, true) }
 
-// Relocation types for s390
+// Relocation types for s390x processors.
 type R_390 int
 
 const (
-	R_390_NONE     R_390 = 0
-	R_390_8        R_390 = 1
-	R_390_12       R_390 = 2
-	R_390_16       R_390 = 3
-	R_390_32       R_390 = 4
-	R_390_PC32     R_390 = 5
-	R_390_GOT12    R_390 = 6
-	R_390_GOT32    R_390 = 7
-	R_390_PLT32    R_390 = 8
-	R_390_COPY     R_390 = 9
-	R_390_GLOB_DAT R_390 = 10
-	R_390_JMP_SLOT R_390 = 11
-	R_390_RELATIVE R_390 = 12
-	R_390_GOTOFF   R_390 = 13
-	R_390_GOTPC    R_390 = 14
-	R_390_GOT16    R_390 = 15
-	R_390_PC16     R_390 = 16
-	R_390_PC16DBL  R_390 = 17
-	R_390_PLT16DBL R_390 = 18
-	R_390_PC32DBL  R_390 = 19
-	R_390_PLT32DBL R_390 = 20
-	R_390_GOTPCDBL R_390 = 21
-	R_390_64       R_390 = 22
-	R_390_PC64     R_390 = 23
-	R_390_GOT64    R_390 = 24
-	R_390_PLT64    R_390 = 25
-	R_390_GOTENT   R_390 = 26
+	R_390_NONE        R_390 = 0
+	R_390_8           R_390 = 1
+	R_390_12          R_390 = 2
+	R_390_16          R_390 = 3
+	R_390_32          R_390 = 4
+	R_390_PC32        R_390 = 5
+	R_390_GOT12       R_390 = 6
+	R_390_GOT32       R_390 = 7
+	R_390_PLT32       R_390 = 8
+	R_390_COPY        R_390 = 9
+	R_390_GLOB_DAT    R_390 = 10
+	R_390_JMP_SLOT    R_390 = 11
+	R_390_RELATIVE    R_390 = 12
+	R_390_GOTOFF      R_390 = 13
+	R_390_GOTPC       R_390 = 14
+	R_390_GOT16       R_390 = 15
+	R_390_PC16        R_390 = 16
+	R_390_PC16DBL     R_390 = 17
+	R_390_PLT16DBL    R_390 = 18
+	R_390_PC32DBL     R_390 = 19
+	R_390_PLT32DBL    R_390 = 20
+	R_390_GOTPCDBL    R_390 = 21
+	R_390_64          R_390 = 22
+	R_390_PC64        R_390 = 23
+	R_390_GOT64       R_390 = 24
+	R_390_PLT64       R_390 = 25
+	R_390_GOTENT      R_390 = 26
+	R_390_GOTOFF16    R_390 = 27
+	R_390_GOTOFF64    R_390 = 28
+	R_390_GOTPLT12    R_390 = 29
+	R_390_GOTPLT16    R_390 = 30
+	R_390_GOTPLT32    R_390 = 31
+	R_390_GOTPLT64    R_390 = 32
+	R_390_GOTPLTENT   R_390 = 33
+	R_390_GOTPLTOFF16 R_390 = 34
+	R_390_GOTPLTOFF32 R_390 = 35
+	R_390_GOTPLTOFF64 R_390 = 36
+	R_390_TLS_LOAD    R_390 = 37
+	R_390_TLS_GDCALL  R_390 = 38
+	R_390_TLS_LDCALL  R_390 = 39
+	R_390_TLS_GD32    R_390 = 40
+	R_390_TLS_GD64    R_390 = 41
+	R_390_TLS_GOTIE12 R_390 = 42
+	R_390_TLS_GOTIE32 R_390 = 43
+	R_390_TLS_GOTIE64 R_390 = 44
+	R_390_TLS_LDM32   R_390 = 45
+	R_390_TLS_LDM64   R_390 = 46
+	R_390_TLS_IE32    R_390 = 47
+	R_390_TLS_IE64    R_390 = 48
+	R_390_TLS_IEENT   R_390 = 49
+	R_390_TLS_LE32    R_390 = 50
+	R_390_TLS_LE64    R_390 = 51
+	R_390_TLS_LDO32   R_390 = 52
+	R_390_TLS_LDO64   R_390 = 53
+	R_390_TLS_DTPMOD  R_390 = 54
+	R_390_TLS_DTPOFF  R_390 = 55
+	R_390_TLS_TPOFF   R_390 = 56
+	R_390_20          R_390 = 57
+	R_390_GOT20       R_390 = 58
+	R_390_GOTPLT20    R_390 = 59
+	R_390_TLS_GOTIE20 R_390 = 60
 )
 
 var r390Strings = []intName{
@@ -1786,6 +1820,40 @@ var r390Strings = []intName{
 	{24, "R_390_GOT64"},
 	{25, "R_390_PLT64"},
 	{26, "R_390_GOTENT"},
+	{27, "R_390_GOTOFF16"},
+	{28, "R_390_GOTOFF64"},
+	{29, "R_390_GOTPLT12"},
+	{30, "R_390_GOTPLT16"},
+	{31, "R_390_GOTPLT32"},
+	{32, "R_390_GOTPLT64"},
+	{33, "R_390_GOTPLTENT"},
+	{34, "R_390_GOTPLTOFF16"},
+	{35, "R_390_GOTPLTOFF32"},
+	{36, "R_390_GOTPLTOFF64"},
+	{37, "R_390_TLS_LOAD"},
+	{38, "R_390_TLS_GDCALL"},
+	{39, "R_390_TLS_LDCALL"},
+	{40, "R_390_TLS_GD32"},
+	{41, "R_390_TLS_GD64"},
+	{42, "R_390_TLS_GOTIE12"},
+	{43, "R_390_TLS_GOTIE32"},
+	{44, "R_390_TLS_GOTIE64"},
+	{45, "R_390_TLS_LDM32"},
+	{46, "R_390_TLS_LDM64"},
+	{47, "R_390_TLS_IE32"},
+	{48, "R_390_TLS_IE64"},
+	{49, "R_390_TLS_IEENT"},
+	{50, "R_390_TLS_LE32"},
+	{51, "R_390_TLS_LE64"},
+	{52, "R_390_TLS_LDO32"},
+	{53, "R_390_TLS_LDO64"},
+	{54, "R_390_TLS_DTPMOD"},
+	{55, "R_390_TLS_DTPOFF"},
+	{56, "R_390_TLS_TPOFF"},
+	{57, "R_390_20"},
+	{58, "R_390_GOT20"},
+	{59, "R_390_GOTPLT20"},
+	{60, "R_390_TLS_GOTIE20"},
 }
 
 func (i R_390) String() string   { return stringName(uint32(i), r390Strings, false) }
@@ -1962,7 +2030,7 @@ type Prog32 struct {
 	Align  uint32 /* Alignment in memory and file. */
 }
 
-// ELF32 Dynamic structure.  The ".dynamic" section contains an array of them.
+// ELF32 Dynamic structure. The ".dynamic" section contains an array of them.
 type Dyn32 struct {
 	Tag int32  /* Entry type. */
 	Val uint32 /* Integer/Address value. */
@@ -1992,8 +2060,8 @@ type Rela32 struct {
 	Addend int32  /* Addend. */
 }
 
-func R_SYM32(info uint32) uint32      { return uint32(info >> 8) }
-func R_TYPE32(info uint32) uint32     { return uint32(info & 0xff) }
+func R_SYM32(info uint32) uint32      { return info >> 8 }
+func R_TYPE32(info uint32) uint32     { return info & 0xff }
 func R_INFO32(sym, typ uint32) uint32 { return sym<<8 | typ }
 
 // ELF32 Symbol.
@@ -2063,7 +2131,7 @@ type Prog64 struct {
 	Align  uint64 /* Alignment in memory and file. */
 }
 
-// ELF64 Dynamic structure.  The ".dynamic" section contains an array of them.
+// ELF64 Dynamic structure. The ".dynamic" section contains an array of them.
 type Dyn64 struct {
 	Tag int64  /* Entry type. */
 	Val uint64 /* Integer/address value */
diff --git a/libgo/go/debug/elf/elf_test.go b/libgo/go/debug/elf/elf_test.go
index e3c51bb717b..f8985a89923 100644
--- a/libgo/go/debug/elf/elf_test.go
+++ b/libgo/go/debug/elf/elf_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/elf/file.go b/libgo/go/debug/elf/file.go
index b028772bfbf..c173ea93316 100644
--- a/libgo/go/debug/elf/file.go
+++ b/libgo/go/debug/elf/file.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -269,7 +269,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	switch f.Class {
 	case ELFCLASS32:
 		hdr := new(Header32)
-		sr.Seek(0, os.SEEK_SET)
+		sr.Seek(0, io.SeekStart)
 		if err := binary.Read(sr, f.ByteOrder, hdr); err != nil {
 			return nil, err
 		}
@@ -288,13 +288,13 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		shstrndx = int(hdr.Shstrndx)
 	case ELFCLASS64:
 		hdr := new(Header64)
-		sr.Seek(0, os.SEEK_SET)
+		sr.Seek(0, io.SeekStart)
 		if err := binary.Read(sr, f.ByteOrder, hdr); err != nil {
 			return nil, err
 		}
 		f.Type = Type(hdr.Type)
 		f.Machine = Machine(hdr.Machine)
-		f.Entry = uint64(hdr.Entry)
+		f.Entry = hdr.Entry
 		if v := Version(hdr.Version); v != f.Version {
 			return nil, &FormatError{0, "mismatched ELF version", v}
 		}
@@ -315,7 +315,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	f.Progs = make([]*Prog, phnum)
 	for i := 0; i < phnum; i++ {
 		off := phoff + int64(i)*int64(phentsize)
-		sr.Seek(off, os.SEEK_SET)
+		sr.Seek(off, io.SeekStart)
 		p := new(Prog)
 		switch f.Class {
 		case ELFCLASS32:
@@ -341,12 +341,12 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			p.ProgHeader = ProgHeader{
 				Type:   ProgType(ph.Type),
 				Flags:  ProgFlag(ph.Flags),
-				Off:    uint64(ph.Off),
-				Vaddr:  uint64(ph.Vaddr),
-				Paddr:  uint64(ph.Paddr),
-				Filesz: uint64(ph.Filesz),
-				Memsz:  uint64(ph.Memsz),
-				Align:  uint64(ph.Align),
+				Off:    ph.Off,
+				Vaddr:  ph.Vaddr,
+				Paddr:  ph.Paddr,
+				Filesz: ph.Filesz,
+				Memsz:  ph.Memsz,
+				Align:  ph.Align,
 			}
 		}
 		p.sr = io.NewSectionReader(r, int64(p.Off), int64(p.Filesz))
@@ -359,7 +359,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	names := make([]uint32, shnum)
 	for i := 0; i < shnum; i++ {
 		off := shoff + int64(i)*int64(shentsize)
-		sr.Seek(off, os.SEEK_SET)
+		sr.Seek(off, io.SeekStart)
 		s := new(Section)
 		switch f.Class {
 		case ELFCLASS32:
@@ -374,8 +374,8 @@ func NewFile(r io.ReaderAt) (*File, error) {
 				Addr:      uint64(sh.Addr),
 				Offset:    uint64(sh.Off),
 				FileSize:  uint64(sh.Size),
-				Link:      uint32(sh.Link),
-				Info:      uint32(sh.Info),
+				Link:      sh.Link,
+				Info:      sh.Info,
 				Addralign: uint64(sh.Addralign),
 				Entsize:   uint64(sh.Entsize),
 			}
@@ -388,13 +388,13 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			s.SectionHeader = SectionHeader{
 				Type:      SectionType(sh.Type),
 				Flags:     SectionFlag(sh.Flags),
-				Offset:    uint64(sh.Off),
-				FileSize:  uint64(sh.Size),
-				Addr:      uint64(sh.Addr),
-				Link:      uint32(sh.Link),
-				Info:      uint32(sh.Info),
-				Addralign: uint64(sh.Addralign),
-				Entsize:   uint64(sh.Entsize),
+				Offset:    sh.Off,
+				FileSize:  sh.Size,
+				Addr:      sh.Addr,
+				Link:      sh.Link,
+				Info:      sh.Info,
+				Addralign: sh.Addralign,
+				Entsize:   sh.Entsize,
 			}
 		}
 		s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.FileSize))
@@ -597,7 +597,7 @@ func (f *File) applyRelocations(dst []byte, rels []byte) error {
 	case f.Class == ELFCLASS64 && f.Machine == EM_MIPS:
 		return f.applyRelocationsMIPS64(dst, rels)
 	case f.Class == ELFCLASS64 && f.Machine == EM_S390:
-		return f.applyRelocationsS390x(dst, rels)
+		return f.applyRelocationss390x(dst, rels)
 	default:
 		return errors.New("applyRelocations: not implemented")
 	}
@@ -913,7 +913,7 @@ func (f *File) applyRelocationsMIPS64(dst []byte, rels []byte) error {
 	return nil
 }
 
-func (f *File) applyRelocationsS390x(dst []byte, rels []byte) error {
+func (f *File) applyRelocationss390x(dst []byte, rels []byte) error {
 	// 24 is the size of Rela64.
 	if len(rels)%24 != 0 {
 		return errors.New("length of relocation section is not a multiple of 24")
@@ -924,7 +924,7 @@ func (f *File) applyRelocationsS390x(dst []byte, rels []byte) error {
 		return err
 	}
 
-	b := bytes.NewBuffer(rels)
+	b := bytes.NewReader(rels)
 	var rela Rela64
 
 	for b.Len() > 0 {
@@ -936,18 +936,26 @@ func (f *File) applyRelocationsS390x(dst []byte, rels []byte) error {
 			continue
 		}
 		sym := &symbols[symNo-1]
+		switch SymType(sym.Info & 0xf) {
+		case STT_SECTION, STT_NOTYPE:
+			break
+		default:
+			continue
+		}
 
 		switch t {
 		case R_390_64:
 			if rela.Off+8 >= uint64(len(dst)) || rela.Addend < 0 {
 				continue
 			}
-			f.ByteOrder.PutUint64(dst[rela.Off:rela.Off+8], uint64(rela.Addend)+uint64(sym.Value))
+			val := sym.Value + uint64(rela.Addend)
+			f.ByteOrder.PutUint64(dst[rela.Off:rela.Off+8], val)
 		case R_390_32:
 			if rela.Off+4 >= uint64(len(dst)) || rela.Addend < 0 {
 				continue
 			}
-			f.ByteOrder.PutUint32(dst[rela.Off:rela.Off+4], uint32(rela.Addend)+uint32(sym.Value))
+			val := uint32(sym.Value) + uint32(rela.Addend)
+			f.ByteOrder.PutUint32(dst[rela.Off:rela.Off+4], val)
 		}
 	}
 
diff --git a/libgo/go/debug/elf/file_test.go b/libgo/go/debug/elf/file_test.go
index 5c0df0f1e9e..b189219a556 100644
--- a/libgo/go/debug/elf/file_test.go
+++ b/libgo/go/debug/elf/file_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -473,6 +473,25 @@ var relocationTests = []relocationTest{
 		},
 	},
 	{
+		"testdata/go-relocation-test-gcc531-s390x.obj",
+		[]relocationTestEntry{
+			{0, &dwarf.Entry{
+				Offset:   0xb,
+				Tag:      dwarf.TagCompileUnit,
+				Children: true,
+				Field: []dwarf.Field{
+					{Attr: dwarf.AttrProducer, Val: "GNU C11 5.3.1 20160316 -march=zEC12 -m64 -mzarch -g -fstack-protector-strong", Class: dwarf.ClassString},
+					{Attr: dwarf.AttrLanguage, Val: int64(12), Class: dwarf.ClassConstant},
+					{Attr: dwarf.AttrName, Val: "hello.c", Class: dwarf.ClassString},
+					{Attr: dwarf.AttrCompDir, Val: "/tmp", Class: dwarf.ClassString},
+					{Attr: dwarf.AttrLowpc, Val: uint64(0x0), Class: dwarf.ClassAddress},
+					{Attr: dwarf.AttrHighpc, Val: int64(58), Class: dwarf.ClassConstant},
+					{Attr: dwarf.AttrStmtList, Val: int64(0), Class: dwarf.ClassLinePtr},
+				},
+			}},
+		},
+	},
+	{
 		"testdata/go-relocation-test-gcc493-mips64le.obj",
 		[]relocationTestEntry{
 			{0, &dwarf.Entry{
@@ -636,7 +655,7 @@ func TestCompressedSection(t *testing.T) {
 	// Test Open method and seeking.
 	buf, have, count := make([]byte, len(b)), make([]bool, len(b)), 0
 	sf := sec.Open()
-	if got, err := sf.Seek(0, 2); got != int64(len(b)) || err != nil {
+	if got, err := sf.Seek(0, io.SeekEnd); got != int64(len(b)) || err != nil {
 		t.Fatalf("want seek end %d, got %d error %v", len(b), got, err)
 	}
 	if n, err := sf.Read(buf); n != 0 || err != io.EOF {
@@ -649,11 +668,11 @@ func TestCompressedSection(t *testing.T) {
 		target := rand.Int63n(int64(len(buf)))
 		var offset int64
 		switch whence {
-		case 0:
+		case io.SeekStart:
 			offset = target
-		case 1:
+		case io.SeekCurrent:
 			offset = target - pos
-		case 2:
+		case io.SeekEnd:
 			offset = target - int64(len(buf))
 		}
 		pos, err = sf.Seek(offset, whence)
@@ -669,7 +688,7 @@ func TestCompressedSection(t *testing.T) {
 		if end > int64(len(buf)) {
 			end = int64(len(buf))
 		}
-		n, err := sf.Read(buf[pos:end])
+		n, err := io.ReadFull(sf, buf[pos:end])
 		if err != nil {
 			t.Fatal(err)
 		}
diff --git a/libgo/go/debug/elf/reader.go b/libgo/go/debug/elf/reader.go
index 17b57165bc3..eab437318d6 100644
--- a/libgo/go/debug/elf/reader.go
+++ b/libgo/go/debug/elf/reader.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -63,11 +63,11 @@ func (r *readSeekerFromReader) Read(p []byte) (n int, err error) {
 func (r *readSeekerFromReader) Seek(offset int64, whence int) (int64, error) {
 	var newOffset int64
 	switch whence {
-	case 0:
+	case io.SeekStart:
 		newOffset = offset
-	case 1:
+	case io.SeekCurrent:
 		newOffset = r.offset + offset
-	case 2:
+	case io.SeekEnd:
 		newOffset = r.size + offset
 	default:
 		return 0, os.ErrInvalid
diff --git a/libgo/go/debug/elf/testdata/go-relocation-test-gcc531-s390x.obj b/libgo/go/debug/elf/testdata/go-relocation-test-gcc531-s390x.obj
new file mode 100644
index 00000000000..caacb9b90a5
--- /dev/null
+++ b/libgo/go/debug/elf/testdata/go-relocation-test-gcc531-s390x.obj
diff --git a/libgo/go/debug/elf/testdata/hello-world-core.gz b/libgo/go/debug/elf/testdata/hello-world-core.gz
index 806af6edbc2..6d76ab0934a 100644
--- a/libgo/go/debug/elf/testdata/hello-world-core.gz
+++ b/libgo/go/debug/elf/testdata/hello-world-core.gz
diff --git a/libgo/go/debug/gosym/pclntab.go b/libgo/go/debug/gosym/pclntab.go
index 6620aefb053..e859d5aed50 100644
--- a/libgo/go/debug/gosym/pclntab.go
+++ b/libgo/go/debug/gosym/pclntab.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -53,7 +53,7 @@ const oldQuantum = 1
 func (t *LineTable) parse(targetPC uint64, targetLine int) (b []byte, pc uint64, line int) {
 	// The PC/line table can be thought of as a sequence of
 	//  <pc update>* <line update>
-	// batches.  Each update batch results in a (pc, line) pair,
+	// batches. Each update batch results in a (pc, line) pair,
 	// where line applies to every PC from pc up to but not
 	// including the pc of the next pair.
 	//
@@ -167,7 +167,7 @@ func (t *LineTable) go12Init() {
 	// Check header: 4-byte magic, two zeros, pc quantum, pointer size.
 	t.go12 = -1 // not Go 1.2 until proven otherwise
 	if len(t.Data) < 16 || t.Data[4] != 0 || t.Data[5] != 0 ||
-		(t.Data[6] != 1 && t.Data[6] != 4) || // pc quantum
+		(t.Data[6] != 1 && t.Data[6] != 2 && t.Data[6] != 4) || // pc quantum
 		(t.Data[7] != 4 && t.Data[7] != 8) { // pointer size
 		return
 	}
@@ -207,8 +207,8 @@ func (t *LineTable) go12Funcs() []Func {
 	funcs := make([]Func, n)
 	for i := range funcs {
 		f := &funcs[i]
-		f.Entry = uint64(t.uintptr(t.functab[2*i*int(t.ptrsize):]))
-		f.End = uint64(t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):]))
+		f.Entry = t.uintptr(t.functab[2*i*int(t.ptrsize):])
+		f.End = t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):])
 		info := t.Data[t.uintptr(t.functab[(2*i+1)*int(t.ptrsize):]):]
 		f.LineTable = t
 		f.FrameSize = int(t.binary.Uint32(info[t.ptrsize+2*4:]))
diff --git a/libgo/go/debug/gosym/pclntab_test.go b/libgo/go/debug/gosym/pclntab_test.go
index 8d4aa547a02..9f82e31ae41 100644
--- a/libgo/go/debug/gosym/pclntab_test.go
+++ b/libgo/go/debug/gosym/pclntab_test.go
@@ -1,10 +1,11 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package gosym
 
 import (
+	"bytes"
 	"debug/elf"
 	"internal/testenv"
 	"io/ioutil"
@@ -42,7 +43,22 @@ func dotest(t *testing.T) {
 	if err := cmd.Run(); err != nil {
 		t.Fatal(err)
 	}
-	cmd = exec.Command("go", "tool", "link", "-H", "linux", "-E", "main",
+
+	// stamp .o file as being 'package main' so that go tool link will accept it
+	data, err := ioutil.ReadFile(pclinetestBinary + ".o")
+	if err != nil {
+		t.Fatal(err)
+	}
+	i := bytes.IndexByte(data, '\n')
+	if i < 0 {
+		t.Fatal("bad binary")
+	}
+	data = append(append(data[:i:i], "\nmain"...), data[i:]...)
+	if err := ioutil.WriteFile(pclinetestBinary+".o", data, 0666); err != nil {
+		t.Fatal(err)
+	}
+
+	cmd = exec.Command("go", "tool", "link", "-H", "linux",
 		"-o", pclinetestBinary, pclinetestBinary+".o")
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
@@ -111,8 +127,6 @@ func parse(file string, f *elf.File, t *testing.T) (*elf.File, *Table) {
 	return f, tab
 }
 
-var goarch = os.Getenv("O")
-
 func TestLineFromAline(t *testing.T) {
 	skipIfNotELF(t)
 
@@ -210,6 +224,7 @@ func TestPCLine(t *testing.T) {
 	defer endtest()
 
 	f, tab := crack(pclinetestBinary, t)
+	defer f.Close()
 	text := f.Section(".text")
 	textdat, err := text.Data()
 	if err != nil {
diff --git a/libgo/go/debug/gosym/symtab.go b/libgo/go/debug/gosym/symtab.go
index 46f07833442..f5f99630950 100644
--- a/libgo/go/debug/gosym/symtab.go
+++ b/libgo/go/debug/gosym/symtab.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,7 +8,7 @@
 package gosym
 
 // The table format is a variant of the format used in Plan 9's a.out
-// format, documented at http://plan9.bell-labs.com/magic/man2html/6/a.out.
+// format, documented at https://9p.io/magic/man2html/6/a.out.
 // The best reference for the differences between the Plan 9 format
 // and the Go format is the runtime source, specifically ../../runtime/symtab.c.
 
@@ -40,8 +40,13 @@ func (s *Sym) Static() bool { return s.Type >= 'a' }
 // PackageName returns the package part of the symbol name,
 // or the empty string if there is none.
 func (s *Sym) PackageName() string {
-	if i := strings.Index(s.Name, "."); i != -1 {
-		return s.Name[0:i]
+	pathend := strings.LastIndex(s.Name, "/")
+	if pathend < 0 {
+		pathend = 0
+	}
+
+	if i := strings.Index(s.Name[pathend:], "."); i != -1 {
+		return s.Name[:pathend+i]
 	}
 	return ""
 }
@@ -49,12 +54,16 @@ func (s *Sym) PackageName() string {
 // ReceiverName returns the receiver type name of this symbol,
 // or the empty string if there is none.
 func (s *Sym) ReceiverName() string {
-	l := strings.Index(s.Name, ".")
-	r := strings.LastIndex(s.Name, ".")
+	pathend := strings.LastIndex(s.Name, "/")
+	if pathend < 0 {
+		pathend = 0
+	}
+	l := strings.Index(s.Name[pathend:], ".")
+	r := strings.LastIndex(s.Name[pathend:], ".")
 	if l == -1 || r == -1 || l == r {
 		return ""
 	}
-	return s.Name[l+1 : r]
+	return s.Name[pathend+l+1 : pathend+r]
 }
 
 // BaseName returns the symbol name without the package or receiver name.
@@ -103,7 +112,7 @@ type Obj struct {
  * Symbol tables
  */
 
-// Table represents a Go symbol table.  It stores all of the
+// Table represents a Go symbol table. It stores all of the
 // symbols decoded from the program and provides methods to translate
 // between symbols, names, and addresses.
 type Table struct {
@@ -294,8 +303,8 @@ func NewTable(symtab []byte, pcln *LineTable) (*Table, error) {
 		t.Syms = t.Syms[0 : n+1]
 		ts := &t.Syms[n]
 		ts.Type = s.typ
-		ts.Value = uint64(s.value)
-		ts.GoType = uint64(s.gotype)
+		ts.Value = s.value
+		ts.GoType = s.gotype
 		switch s.typ {
 		default:
 			// rewrite name to use . instead of · (c2 b7)
@@ -353,7 +362,7 @@ func NewTable(symtab []byte, pcln *LineTable) (*Table, error) {
 	}
 
 	// Count text symbols and attach frame sizes, parameters, and
-	// locals to them.  Also, find object file boundaries.
+	// locals to them. Also, find object file boundaries.
 	lastf := 0
 	for i := 0; i < len(t.Syms); i++ {
 		sym := &t.Syms[i]
@@ -503,7 +512,7 @@ func (t *Table) PCToLine(pc uint64) (file string, line int, fn *Func) {
 }
 
 // LineToPC looks up the first program counter on the given line in
-// the named file.  It returns UnknownPathError or UnknownLineError if
+// the named file. It returns UnknownPathError or UnknownLineError if
 // there is an error looking up this line.
 func (t *Table) LineToPC(file string, line int) (pc uint64, fn *Func, err error) {
 	obj, ok := t.Files[file]
diff --git a/libgo/go/debug/gosym/symtab_test.go b/libgo/go/debug/gosym/symtab_test.go
new file mode 100644
index 00000000000..08e86336b8e
--- /dev/null
+++ b/libgo/go/debug/gosym/symtab_test.go
@@ -0,0 +1,43 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gosym
+
+import (
+	"fmt"
+	"testing"
+)
+
+func assertString(t *testing.T, dsc, out, tgt string) {
+	if out != tgt {
+		t.Fatalf("Expected: %q Actual: %q for %s", tgt, out, dsc)
+	}
+}
+
+func TestStandardLibPackage(t *testing.T) {
+	s1 := Sym{Name: "io.(*LimitedReader).Read"}
+	s2 := Sym{Name: "io.NewSectionReader"}
+	assertString(t, fmt.Sprintf("package of %q", s1.Name), s1.PackageName(), "io")
+	assertString(t, fmt.Sprintf("package of %q", s2.Name), s2.PackageName(), "io")
+	assertString(t, fmt.Sprintf("receiver of %q", s1.Name), s1.ReceiverName(), "(*LimitedReader)")
+	assertString(t, fmt.Sprintf("receiver of %q", s2.Name), s2.ReceiverName(), "")
+}
+
+func TestStandardLibPathPackage(t *testing.T) {
+	s1 := Sym{Name: "debug/gosym.(*LineTable).PCToLine"}
+	s2 := Sym{Name: "debug/gosym.NewTable"}
+	assertString(t, fmt.Sprintf("package of %q", s1.Name), s1.PackageName(), "debug/gosym")
+	assertString(t, fmt.Sprintf("package of %q", s2.Name), s2.PackageName(), "debug/gosym")
+	assertString(t, fmt.Sprintf("receiver of %q", s1.Name), s1.ReceiverName(), "(*LineTable)")
+	assertString(t, fmt.Sprintf("receiver of %q", s2.Name), s2.ReceiverName(), "")
+}
+
+func TestRemotePackage(t *testing.T) {
+	s1 := Sym{Name: "github.com/docker/doc.ker/pkg/mflag.(*FlagSet).PrintDefaults"}
+	s2 := Sym{Name: "github.com/docker/doc.ker/pkg/mflag.PrintDefaults"}
+	assertString(t, fmt.Sprintf("package of %q", s1.Name), s1.PackageName(), "github.com/docker/doc.ker/pkg/mflag")
+	assertString(t, fmt.Sprintf("package of %q", s2.Name), s2.PackageName(), "github.com/docker/doc.ker/pkg/mflag")
+	assertString(t, fmt.Sprintf("receiver of %q", s1.Name), s1.ReceiverName(), "(*FlagSet)")
+	assertString(t, fmt.Sprintf("receiver of %q", s2.Name), s2.ReceiverName(), "")
+}
diff --git a/libgo/go/debug/macho/fat.go b/libgo/go/debug/macho/fat.go
index 93b8315263c..6bd730dc0bb 100644
--- a/libgo/go/debug/macho/fat.go
+++ b/libgo/go/debug/macho/fat.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -122,18 +122,18 @@ func NewFatFile(r io.ReaderAt) (*FatFile, error) {
 
 // OpenFat opens the named file using os.Open and prepares it for use as a Mach-O
 // universal binary.
-func OpenFat(name string) (ff *FatFile, err error) {
+func OpenFat(name string) (*FatFile, error) {
 	f, err := os.Open(name)
 	if err != nil {
 		return nil, err
 	}
-	ff, err = NewFatFile(f)
+	ff, err := NewFatFile(f)
 	if err != nil {
 		f.Close()
 		return nil, err
 	}
 	ff.closer = f
-	return
+	return ff, nil
 }
 
 func (ff *FatFile) Close() error {
diff --git a/libgo/go/debug/macho/file.go b/libgo/go/debug/macho/file.go
index a7599aa5b2b..223346f10d7 100644
--- a/libgo/go/debug/macho/file.go
+++ b/libgo/go/debug/macho/file.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -474,7 +474,7 @@ func (f *File) DWARF() (*dwarf.Data, error) {
 	// There are many other DWARF sections, but these
 	// are the ones the debug/dwarf package uses.
 	// Don't bother loading others.
-	var names = [...]string{"abbrev", "info", "line", "str"}
+	var names = [...]string{"abbrev", "info", "line", "ranges", "str"}
 	var dat [len(names)][]byte
 	for i, name := range names {
 		name = "__debug_" + name
@@ -489,8 +489,8 @@ func (f *File) DWARF() (*dwarf.Data, error) {
 		dat[i] = b
 	}
 
-	abbrev, info, line, str := dat[0], dat[1], dat[2], dat[3]
-	return dwarf.New(abbrev, nil, nil, info, line, nil, nil, str)
+	abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4]
+	return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
 }
 
 // ImportedSymbols returns the names of all symbols
diff --git a/libgo/go/debug/macho/file_test.go b/libgo/go/debug/macho/file_test.go
index 4797780ce77..9ff6c5d96e3 100644
--- a/libgo/go/debug/macho/file_test.go
+++ b/libgo/go/debug/macho/file_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/macho/macho.go b/libgo/go/debug/macho/macho.go
index d9678c8eda4..31647536ac5 100644
--- a/libgo/go/debug/macho/macho.go
+++ b/libgo/go/debug/macho/macho.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -291,26 +291,3 @@ func stringName(i uint32, names []intName, goSyntax bool) string {
 	}
 	return strconv.FormatUint(uint64(i), 10)
 }
-
-func flagName(i uint32, names []intName, goSyntax bool) string {
-	s := ""
-	for _, n := range names {
-		if n.i&i == n.i {
-			if len(s) > 0 {
-				s += "+"
-			}
-			if goSyntax {
-				s += "macho."
-			}
-			s += n.s
-			i -= n.i
-		}
-	}
-	if len(s) == 0 {
-		return "0x" + strconv.FormatUint(uint64(i), 16)
-	}
-	if i != 0 {
-		s += "+0x" + strconv.FormatUint(uint64(i), 16)
-	}
-	return s
-}
diff --git a/libgo/go/debug/pe/file.go b/libgo/go/debug/pe/file.go
index 3df4ae73681..3074ba0f506 100644
--- a/libgo/go/debug/pe/file.go
+++ b/libgo/go/debug/pe/file.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,11 +8,9 @@ package pe
 import (
 	"debug/dwarf"
 	"encoding/binary"
-	"errors"
 	"fmt"
 	"io"
 	"os"
-	"strconv"
 )
 
 // A File represents an open PE file.
@@ -20,83 +18,13 @@ type File struct {
 	FileHeader
 	OptionalHeader interface{} // of type *OptionalHeader32 or *OptionalHeader64
 	Sections       []*Section
-	Symbols        []*Symbol
+	Symbols        []*Symbol    // COFF symbols with auxiliary symbol records removed
+	_COFFSymbols   []COFFSymbol // all COFF symbols (including auxiliary symbol records)
+	_StringTable   _StringTable
 
 	closer io.Closer
 }
 
-type SectionHeader struct {
-	Name                 string
-	VirtualSize          uint32
-	VirtualAddress       uint32
-	Size                 uint32
-	Offset               uint32
-	PointerToRelocations uint32
-	PointerToLineNumbers uint32
-	NumberOfRelocations  uint16
-	NumberOfLineNumbers  uint16
-	Characteristics      uint32
-}
-
-type Section struct {
-	SectionHeader
-
-	// Embed ReaderAt for ReadAt method.
-	// Do not embed SectionReader directly
-	// to avoid having Read and Seek.
-	// If a client wants Read and Seek it must use
-	// Open() to avoid fighting over the seek offset
-	// with other clients.
-	io.ReaderAt
-	sr *io.SectionReader
-}
-
-type Symbol struct {
-	Name          string
-	Value         uint32
-	SectionNumber int16
-	Type          uint16
-	StorageClass  uint8
-}
-
-type ImportDirectory struct {
-	OriginalFirstThunk uint32
-	TimeDateStamp      uint32
-	ForwarderChain     uint32
-	Name               uint32
-	FirstThunk         uint32
-
-	dll string
-}
-
-// Data reads and returns the contents of the PE section.
-func (s *Section) Data() ([]byte, error) {
-	dat := make([]byte, s.sr.Size())
-	n, err := s.sr.ReadAt(dat, 0)
-	if n == len(dat) {
-		err = nil
-	}
-	return dat[0:n], err
-}
-
-// Open returns a new ReadSeeker reading the PE section.
-func (s *Section) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) }
-
-type FormatError struct {
-	off int64
-	msg string
-	val interface{}
-}
-
-func (e *FormatError) Error() string {
-	msg := e.msg
-	if e.val != nil {
-		msg += fmt.Sprintf(" '%v'", e.val)
-	}
-	msg += fmt.Sprintf(" in record at byte %#x", e.off)
-	return msg
-}
-
 // Open opens the named file using os.Open and prepares it for use as a PE binary.
 func Open(name string) (*File, error) {
 	f, err := os.Open(name)
@@ -129,6 +57,8 @@ var (
 	sizeofOptionalHeader64 = uint16(binary.Size(OptionalHeader64{}))
 )
 
+// TODO(brainman): add Load function, as a replacement for NewFile, that does not call removeAuxSymbols (for performance)
+
 // NewFile creates a new File for accessing a PE binary in an underlying reader.
 func NewFile(r io.ReaderAt) (*File, error) {
 	f := new(File)
@@ -144,66 +74,42 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		var sign [4]byte
 		r.ReadAt(sign[:], signoff)
 		if !(sign[0] == 'P' && sign[1] == 'E' && sign[2] == 0 && sign[3] == 0) {
-			return nil, errors.New("Invalid PE File Format.")
+			return nil, fmt.Errorf("Invalid PE COFF file signature of %v.", sign)
 		}
 		base = signoff + 4
 	} else {
 		base = int64(0)
 	}
-	sr.Seek(base, os.SEEK_SET)
+	sr.Seek(base, io.SeekStart)
 	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
 		return nil, err
 	}
-	if f.FileHeader.Machine != IMAGE_FILE_MACHINE_UNKNOWN && f.FileHeader.Machine != IMAGE_FILE_MACHINE_AMD64 && f.FileHeader.Machine != IMAGE_FILE_MACHINE_I386 {
-		return nil, errors.New("Invalid PE File Format.")
+	switch f.FileHeader.Machine {
+	case IMAGE_FILE_MACHINE_UNKNOWN, IMAGE_FILE_MACHINE_AMD64, IMAGE_FILE_MACHINE_I386:
+	default:
+		return nil, fmt.Errorf("Unrecognised COFF file header machine value of 0x%x.", f.FileHeader.Machine)
 	}
 
-	var ss []byte
-	if f.FileHeader.NumberOfSymbols > 0 {
-		// Get COFF string table, which is located at the end of the COFF symbol table.
-		sr.Seek(int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols), os.SEEK_SET)
-		var l uint32
-		if err := binary.Read(sr, binary.LittleEndian, &l); err != nil {
-			return nil, err
-		}
-		ss = make([]byte, l)
-		if _, err := r.ReadAt(ss, int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols)); err != nil {
-			return nil, err
-		}
+	var err error
 
-		// Process COFF symbol table.
-		sr.Seek(int64(f.FileHeader.PointerToSymbolTable), os.SEEK_SET)
-		aux := uint8(0)
-		for i := 0; i < int(f.FileHeader.NumberOfSymbols); i++ {
-			cs := new(COFFSymbol)
-			if err := binary.Read(sr, binary.LittleEndian, cs); err != nil {
-				return nil, err
-			}
-			if aux > 0 {
-				aux--
-				continue
-			}
-			var name string
-			if cs.Name[0] == 0 && cs.Name[1] == 0 && cs.Name[2] == 0 && cs.Name[3] == 0 {
-				si := int(binary.LittleEndian.Uint32(cs.Name[4:]))
-				name, _ = getString(ss, si)
-			} else {
-				name = cstring(cs.Name[:])
-			}
-			aux = cs.NumberOfAuxSymbols
-			s := &Symbol{
-				Name:          name,
-				Value:         cs.Value,
-				SectionNumber: cs.SectionNumber,
-				Type:          cs.Type,
-				StorageClass:  cs.StorageClass,
-			}
-			f.Symbols = append(f.Symbols, s)
-		}
+	// Read string table.
+	f._StringTable, err = readStringTable(&f.FileHeader, sr)
+	if err != nil {
+		return nil, err
+	}
+
+	// Read symbol table.
+	f._COFFSymbols, err = readCOFFSymbols(&f.FileHeader, sr)
+	if err != nil {
+		return nil, err
+	}
+	f.Symbols, err = removeAuxSymbols(f._COFFSymbols, f._StringTable)
+	if err != nil {
+		return nil, err
 	}
 
 	// Read optional header.
-	sr.Seek(base, os.SEEK_SET)
+	sr.Seek(base, io.SeekStart)
 	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
 		return nil, err
 	}
@@ -235,12 +141,9 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		if err := binary.Read(sr, binary.LittleEndian, sh); err != nil {
 			return nil, err
 		}
-		var name string
-		if sh.Name[0] == '\x2F' {
-			si, _ := strconv.Atoi(cstring(sh.Name[1:]))
-			name, _ = getString(ss, si)
-		} else {
-			name = cstring(sh.Name[0:])
+		name, err := sh.fullName(f._StringTable)
+		if err != nil {
+			return nil, err
 		}
 		s := new(Section)
 		s.SectionHeader = SectionHeader{
@@ -255,18 +158,34 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			NumberOfLineNumbers:  sh.NumberOfLineNumbers,
 			Characteristics:      sh.Characteristics,
 		}
-		s.sr = io.NewSectionReader(r, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size))
+		r2 := r
+		if sh.PointerToRawData == 0 { // .bss must have all 0s
+			r2 = zeroReaderAt{}
+		}
+		s.sr = io.NewSectionReader(r2, int64(s.SectionHeader.Offset), int64(s.SectionHeader.Size))
 		s.ReaderAt = s.sr
 		f.Sections[i] = s
 	}
+	for i := range f.Sections {
+		var err error
+		f.Sections[i]._Relocs, err = readRelocs(&f.Sections[i].SectionHeader, sr)
+		if err != nil {
+			return nil, err
+		}
+	}
+
 	return f, nil
 }
 
-func cstring(b []byte) string {
-	var i int
-	for i = 0; i < len(b) && b[i] != 0; i++ {
+// zeroReaderAt is ReaderAt that reads 0s.
+type zeroReaderAt struct{}
+
+// ReadAt writes len(p) 0s into p.
+func (w zeroReaderAt) ReadAt(p []byte, off int64) (n int, err error) {
+	for i := range p {
+		p[i] = 0
 	}
-	return string(b[0:i])
+	return len(p), nil
 }
 
 // getString extracts a string from symbol string table.
@@ -298,7 +217,7 @@ func (f *File) DWARF() (*dwarf.Data, error) {
 	// There are many other DWARF sections, but these
 	// are the ones the debug/dwarf package uses.
 	// Don't bother loading others.
-	var names = [...]string{"abbrev", "info", "line", "str"}
+	var names = [...]string{"abbrev", "info", "line", "ranges", "str"}
 	var dat [len(names)][]byte
 	for i, name := range names {
 		name = ".debug_" + name
@@ -316,8 +235,20 @@ func (f *File) DWARF() (*dwarf.Data, error) {
 		dat[i] = b
 	}
 
-	abbrev, info, line, str := dat[0], dat[1], dat[2], dat[3]
-	return dwarf.New(abbrev, nil, nil, info, line, nil, nil, str)
+	abbrev, info, line, ranges, str := dat[0], dat[1], dat[2], dat[3], dat[4]
+	return dwarf.New(abbrev, nil, nil, info, line, nil, ranges, str)
+}
+
+// TODO(brainman): document ImportDirectory once we decide what to do with it.
+
+type ImportDirectory struct {
+	OriginalFirstThunk uint32
+	TimeDateStamp      uint32
+	ForwarderChain     uint32
+	Name               uint32
+	FirstThunk         uint32
+
+	dll string
 }
 
 // ImportedSymbols returns the names of all symbols
@@ -347,6 +278,12 @@ func (f *File) ImportedSymbols() ([]string, error) {
 		}
 		ida = append(ida, dt)
 	}
+	// TODO(brainman): this needs to be rewritten
+	//  ds.Data() return contets of .idata section. Why store in variable called "names"?
+	//  Why we are retrieving it second time? We already have it in "d", and it is not modified anywhere.
+	//  getString does not extracts a string from symbol string table (as getString doco says).
+	//  Why ds.Data() called again and again in the loop?
+	//  Needs test before rewrite.
 	names, _ := ds.Data()
 	var all []string
 	for _, dt := range ida {
@@ -395,3 +332,12 @@ func (f *File) ImportedLibraries() ([]string, error) {
 	// cgo -dynimport don't use this for windows PE, so just return.
 	return nil, nil
 }
+
+// FormatError is unused.
+// The type is retained for compatibility.
+type FormatError struct {
+}
+
+func (e *FormatError) Error() string {
+	return "unknown error"
+}
diff --git a/libgo/go/debug/pe/file_test.go b/libgo/go/debug/pe/file_test.go
index 316a569ede9..964caf56ec7 100644
--- a/libgo/go/debug/pe/file_test.go
+++ b/libgo/go/debug/pe/file_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,6 +6,7 @@ package pe
 
 import (
 	"debug/dwarf"
+	"internal/testenv"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -104,6 +105,41 @@ var fileTests = []fileTest{
 		},
 	},
 	{
+		file: "testdata/gcc-386-mingw-no-symbols-exec",
+		hdr:  FileHeader{0x14c, 0x8, 0x69676572, 0x0, 0x0, 0xe0, 0x30f},
+		opthdr: &OptionalHeader32{0x10b, 0x2, 0x18, 0xe00, 0x1e00, 0x200, 0x1280, 0x1000, 0x2000, 0x400000, 0x1000, 0x200, 0x4, 0x0, 0x1, 0x0, 0x4, 0x0, 0x0, 0x9000, 0x400, 0x5306, 0x3, 0x0, 0x200000, 0x1000, 0x100000, 0x1000, 0x0, 0x10,
+			[16]DataDirectory{
+				{0x0, 0x0},
+				{0x6000, 0x378},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x8004, 0x18},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x60b8, 0x7c},
+				{0x0, 0x0},
+				{0x0, 0x0},
+				{0x0, 0x0},
+			},
+		},
+		sections: []*SectionHeader{
+			{".text", 0xc64, 0x1000, 0xe00, 0x400, 0x0, 0x0, 0x0, 0x0, 0x60500060},
+			{".data", 0x10, 0x2000, 0x200, 0x1200, 0x0, 0x0, 0x0, 0x0, 0xc0300040},
+			{".rdata", 0x134, 0x3000, 0x200, 0x1400, 0x0, 0x0, 0x0, 0x0, 0x40300040},
+			{".eh_fram", 0x3a0, 0x4000, 0x400, 0x1600, 0x0, 0x0, 0x0, 0x0, 0x40300040},
+			{".bss", 0x60, 0x5000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xc0300080},
+			{".idata", 0x378, 0x6000, 0x400, 0x1a00, 0x0, 0x0, 0x0, 0x0, 0xc0300040},
+			{".CRT", 0x18, 0x7000, 0x200, 0x1e00, 0x0, 0x0, 0x0, 0x0, 0xc0300040},
+			{".tls", 0x20, 0x8000, 0x200, 0x2000, 0x0, 0x0, 0x0, 0x0, 0xc0300040},
+		},
+		hasNoDwarfInfo: true,
+	},
+	{
 		file: "testdata/gcc-amd64-mingw-obj",
 		hdr:  FileHeader{0x8664, 0x6, 0x0, 0x198, 0x12, 0x0, 0x4},
 		sections: []*SectionHeader{
@@ -307,3 +343,75 @@ func main() {
 	}
 	t.Fatal("main.main not found")
 }
+
+func TestBSSHasZeros(t *testing.T) {
+	testenv.MustHaveExec(t)
+
+	if runtime.GOOS != "windows" {
+		t.Skip("skipping windows only test")
+	}
+	gccpath, err := exec.LookPath("gcc")
+	if err != nil {
+		t.Skip("skipping test: gcc is missing")
+	}
+
+	tmpdir, err := ioutil.TempDir("", "TestBSSHasZeros")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpdir)
+
+	srcpath := filepath.Join(tmpdir, "a.c")
+	src := `
+#include <stdio.h>
+
+int zero = 0;
+
+int
+main(void)
+{
+	printf("%d\n", zero);
+	return 0;
+}
+`
+	err = ioutil.WriteFile(srcpath, []byte(src), 0644)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	objpath := filepath.Join(tmpdir, "a.obj")
+	cmd := exec.Command(gccpath, "-c", srcpath, "-o", objpath)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed to build object file: %v - %v", err, string(out))
+	}
+
+	f, err := Open(objpath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+
+	var bss *Section
+	for _, sect := range f.Sections {
+		if sect.Name == ".bss" {
+			bss = sect
+			break
+		}
+	}
+	if bss == nil {
+		t.Fatal("could not find .bss section")
+	}
+	data, err := bss.Data()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(data) == 0 {
+		t.Fatalf("%s file .bss section cannot be empty", objpath)
+	}
+	for _, b := range data {
+		if b != 0 {
+			t.Fatalf(".bss section has non zero bytes: %v", data)
+		}
+	}
+}
diff --git a/libgo/go/debug/pe/pe.go b/libgo/go/debug/pe/pe.go
index 8e90b1b513a..8050d59c70d 100644
--- a/libgo/go/debug/pe/pe.go
+++ b/libgo/go/debug/pe/pe.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -86,30 +86,6 @@ type OptionalHeader64 struct {
 	DataDirectory               [16]DataDirectory
 }
 
-type SectionHeader32 struct {
-	Name                 [8]uint8
-	VirtualSize          uint32
-	VirtualAddress       uint32
-	SizeOfRawData        uint32
-	PointerToRawData     uint32
-	PointerToRelocations uint32
-	PointerToLineNumbers uint32
-	NumberOfRelocations  uint16
-	NumberOfLineNumbers  uint16
-	Characteristics      uint32
-}
-
-const COFFSymbolSize = 18
-
-type COFFSymbol struct {
-	Name               [8]uint8
-	Value              uint32
-	SectionNumber      int16
-	Type               uint16
-	StorageClass       uint8
-	NumberOfAuxSymbols uint8
-}
-
 const (
 	IMAGE_FILE_MACHINE_UNKNOWN   = 0x0
 	IMAGE_FILE_MACHINE_AM33      = 0x1d3
diff --git a/libgo/go/debug/pe/section.go b/libgo/go/debug/pe/section.go
new file mode 100644
index 00000000000..8e6690f0820
--- /dev/null
+++ b/libgo/go/debug/pe/section.go
@@ -0,0 +1,111 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"strconv"
+)
+
+// SectionHeader32 represents real PE COFF section header.
+type SectionHeader32 struct {
+	Name                 [8]uint8
+	VirtualSize          uint32
+	VirtualAddress       uint32
+	SizeOfRawData        uint32
+	PointerToRawData     uint32
+	PointerToRelocations uint32
+	PointerToLineNumbers uint32
+	NumberOfRelocations  uint16
+	NumberOfLineNumbers  uint16
+	Characteristics      uint32
+}
+
+// fullName finds real name of section sh. Normally name is stored
+// in sh.Name, but if it is longer then 8 characters, it is stored
+// in COFF string table st instead.
+func (sh *SectionHeader32) fullName(st _StringTable) (string, error) {
+	if sh.Name[0] != '/' {
+		return cstring(sh.Name[:]), nil
+	}
+	i, err := strconv.Atoi(cstring(sh.Name[1:]))
+	if err != nil {
+		return "", err
+	}
+	return st.String(uint32(i))
+}
+
+// TODO(brainman): copy all IMAGE_REL_* consts from ldpe.go here
+
+// _Reloc represents a PE COFF relocation.
+// Each section contains its own relocation list.
+type _Reloc struct {
+	VirtualAddress   uint32
+	SymbolTableIndex uint32
+	Type             uint16
+}
+
+func readRelocs(sh *SectionHeader, r io.ReadSeeker) ([]_Reloc, error) {
+	if sh.NumberOfRelocations <= 0 {
+		return nil, nil
+	}
+	_, err := r.Seek(int64(sh.PointerToRelocations), io.SeekStart)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to %q section relocations: %v", sh.Name, err)
+	}
+	relocs := make([]_Reloc, sh.NumberOfRelocations)
+	err = binary.Read(r, binary.LittleEndian, relocs)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read section relocations: %v", err)
+	}
+	return relocs, nil
+}
+
+// SectionHeader is similar to SectionHeader32 with Name
+// field replaced by Go string.
+type SectionHeader struct {
+	Name                 string
+	VirtualSize          uint32
+	VirtualAddress       uint32
+	Size                 uint32
+	Offset               uint32
+	PointerToRelocations uint32
+	PointerToLineNumbers uint32
+	NumberOfRelocations  uint16
+	NumberOfLineNumbers  uint16
+	Characteristics      uint32
+}
+
+// Section provides access to PE COFF section.
+type Section struct {
+	SectionHeader
+	_Relocs []_Reloc
+
+	// Embed ReaderAt for ReadAt method.
+	// Do not embed SectionReader directly
+	// to avoid having Read and Seek.
+	// If a client wants Read and Seek it must use
+	// Open() to avoid fighting over the seek offset
+	// with other clients.
+	io.ReaderAt
+	sr *io.SectionReader
+}
+
+// Data reads and returns the contents of the PE section s.
+func (s *Section) Data() ([]byte, error) {
+	dat := make([]byte, s.sr.Size())
+	n, err := s.sr.ReadAt(dat, 0)
+	if n == len(dat) {
+		err = nil
+	}
+	return dat[0:n], err
+}
+
+// Open returns a new ReadSeeker reading the PE section s.
+func (s *Section) Open() io.ReadSeeker {
+	return io.NewSectionReader(s.sr, 0, 1<<63-1)
+}
diff --git a/libgo/go/debug/pe/string.go b/libgo/go/debug/pe/string.go
new file mode 100644
index 00000000000..69837f6d019
--- /dev/null
+++ b/libgo/go/debug/pe/string.go
@@ -0,0 +1,66 @@
+// Copyright 2016 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+// cstring converts ASCII byte sequence b to string.
+// It stops once it finds 0 or reaches end of b.
+func cstring(b []byte) string {
+	var i int
+	for i = 0; i < len(b) && b[i] != 0; i++ {
+	}
+	return string(b[:i])
+}
+
+// _StringTable is a COFF string table.
+type _StringTable []byte
+
+func readStringTable(fh *FileHeader, r io.ReadSeeker) (_StringTable, error) {
+	// COFF string table is located right after COFF symbol table.
+	if fh.PointerToSymbolTable <= 0 {
+		return nil, nil
+	}
+	offset := fh.PointerToSymbolTable + COFFSymbolSize*fh.NumberOfSymbols
+	_, err := r.Seek(int64(offset), io.SeekStart)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to string table: %v", err)
+	}
+	var l uint32
+	err = binary.Read(r, binary.LittleEndian, &l)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read string table length: %v", err)
+	}
+	// string table length includes itself
+	if l <= 4 {
+		return nil, nil
+	}
+	l -= 4
+	buf := make([]byte, l)
+	_, err = io.ReadFull(r, buf)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read string table: %v", err)
+	}
+	return _StringTable(buf), nil
+}
+
+// TODO(brainman): decide if start parameter should be int instead of uint32
+
+// String extracts string from COFF string table st at offset start.
+func (st _StringTable) String(start uint32) (string, error) {
+	// start includes 4 bytes of string table length
+	if start < 4 {
+		return "", fmt.Errorf("offset %d is before the start of string table", start)
+	}
+	start -= 4
+	if int(start) > len(st) {
+		return "", fmt.Errorf("offset %d is beyond the end of string table", start)
+	}
+	return cstring(st[start:]), nil
+}
diff --git a/libgo/go/debug/pe/symbol.go b/libgo/go/debug/pe/symbol.go
new file mode 100644
index 00000000000..7b8cbf236be
--- /dev/null
+++ b/libgo/go/debug/pe/symbol.go
@@ -0,0 +1,95 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package pe
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+const COFFSymbolSize = 18
+
+// COFFSymbol represents single COFF symbol table record.
+type COFFSymbol struct {
+	Name               [8]uint8
+	Value              uint32
+	SectionNumber      int16
+	Type               uint16
+	StorageClass       uint8
+	NumberOfAuxSymbols uint8
+}
+
+func readCOFFSymbols(fh *FileHeader, r io.ReadSeeker) ([]COFFSymbol, error) {
+	if fh.NumberOfSymbols <= 0 {
+		return nil, nil
+	}
+	_, err := r.Seek(int64(fh.PointerToSymbolTable), io.SeekStart)
+	if err != nil {
+		return nil, fmt.Errorf("fail to seek to symbol table: %v", err)
+	}
+	syms := make([]COFFSymbol, fh.NumberOfSymbols)
+	err = binary.Read(r, binary.LittleEndian, syms)
+	if err != nil {
+		return nil, fmt.Errorf("fail to read symbol table: %v", err)
+	}
+	return syms, nil
+}
+
+// isSymNameOffset checks symbol name if it is encoded as offset into string table.
+func isSymNameOffset(name [8]byte) (bool, uint32) {
+	if name[0] == 0 && name[1] == 0 && name[2] == 0 && name[3] == 0 {
+		return true, binary.LittleEndian.Uint32(name[4:])
+	}
+	return false, 0
+}
+
+// _FullName finds real name of symbol sym. Normally name is stored
+// in sym.Name, but if it is longer then 8 characters, it is stored
+// in COFF string table st instead.
+func (sym *COFFSymbol) _FullName(st _StringTable) (string, error) {
+	if ok, offset := isSymNameOffset(sym.Name); ok {
+		return st.String(offset)
+	}
+	return cstring(sym.Name[:]), nil
+}
+
+func removeAuxSymbols(allsyms []COFFSymbol, st _StringTable) ([]*Symbol, error) {
+	if len(allsyms) == 0 {
+		return nil, nil
+	}
+	syms := make([]*Symbol, 0)
+	aux := uint8(0)
+	for _, sym := range allsyms {
+		if aux > 0 {
+			aux--
+			continue
+		}
+		name, err := sym._FullName(st)
+		if err != nil {
+			return nil, err
+		}
+		aux = sym.NumberOfAuxSymbols
+		s := &Symbol{
+			Name:          name,
+			Value:         sym.Value,
+			SectionNumber: sym.SectionNumber,
+			Type:          sym.Type,
+			StorageClass:  sym.StorageClass,
+		}
+		syms = append(syms, s)
+	}
+	return syms, nil
+}
+
+// Symbol is similar to COFFSymbol with Name field replaced
+// by Go string. Symbol also does not have NumberOfAuxSymbols.
+type Symbol struct {
+	Name          string
+	Value         uint32
+	SectionNumber int16
+	Type          uint16
+	StorageClass  uint8
+}
diff --git a/libgo/go/debug/pe/testdata/gcc-386-mingw-no-symbols-exec b/libgo/go/debug/pe/testdata/gcc-386-mingw-no-symbols-exec
new file mode 100644
index 00000000000..329dca60b91
--- /dev/null
+++ b/libgo/go/debug/pe/testdata/gcc-386-mingw-no-symbols-exec
diff --git a/libgo/go/debug/plan9obj/file.go b/libgo/go/debug/plan9obj/file.go
index b11ed86f185..c78e35d0008 100644
--- a/libgo/go/debug/plan9obj/file.go
+++ b/libgo/go/debug/plan9obj/file.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/plan9obj/file_test.go b/libgo/go/debug/plan9obj/file_test.go
index cfd7a61d1cd..7e107bca2f5 100644
--- a/libgo/go/debug/plan9obj/file_test.go
+++ b/libgo/go/debug/plan9obj/file_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/debug/plan9obj/plan9obj.go b/libgo/go/debug/plan9obj/plan9obj.go
index af9858562f9..7a194514c2c 100644
--- a/libgo/go/debug/plan9obj/plan9obj.go
+++ b/libgo/go/debug/plan9obj/plan9obj.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/ascii85/ascii85.go b/libgo/go/encoding/ascii85/ascii85.go
index 4d7193873a2..d42eb0ab00a 100644
--- a/libgo/go/encoding/ascii85/ascii85.go
+++ b/libgo/go/encoding/ascii85/ascii85.go
@@ -20,7 +20,7 @@ import (
 //
 // The encoding handles 4-byte chunks, using a special encoding
 // for the last fragment, so Encode is not appropriate for use on
-// individual blocks of a large data stream.  Use NewEncoder() instead.
+// individual blocks of a large data stream. Use NewEncoder() instead.
 //
 // Often, ascii85-encoded data is wrapped in <~ and ~> symbols.
 // Encode does not add these.
@@ -85,7 +85,7 @@ func Encode(dst, src []byte) int {
 // MaxEncodedLen returns the maximum length of an encoding of n source bytes.
 func MaxEncodedLen(n int) int { return (n + 3) / 4 * 5 }
 
-// NewEncoder returns a new ascii85 stream encoder.  Data written to
+// NewEncoder returns a new ascii85 stream encoder. Data written to
 // the returned writer will be encoded and then written to w.
 // Ascii85 encodings operate in 32-bit blocks; when finished
 // writing, the caller must Close the returned encoder to flush any
@@ -294,7 +294,7 @@ func (d *decoder) Read(p []byte) (n int, err error) {
 			}
 		}
 
-		// Out of input, out of decoded output.  Check errors.
+		// Out of input, out of decoded output. Check errors.
 		if d.err != nil {
 			return 0, d.err
 		}
diff --git a/libgo/go/encoding/asn1/asn1.go b/libgo/go/encoding/asn1/asn1.go
index 8bafefd52bb..2b5ad08551e 100644
--- a/libgo/go/encoding/asn1/asn1.go
+++ b/libgo/go/encoding/asn1/asn1.go
@@ -393,7 +393,7 @@ func isPrintable(b byte) bool {
 // byte slice and returns it.
 func parseIA5String(bytes []byte) (ret string, err error) {
 	for _, b := range bytes {
-		if b >= 0x80 {
+		if b >= utf8.RuneSelf {
 			err = SyntaxError{"IA5String contains invalid character"}
 			return
 		}
@@ -461,6 +461,11 @@ func parseTagAndLength(bytes []byte, initOffset int) (ret tagAndLength, offset i
 		if err != nil {
 			return
 		}
+		// Tags should be encoded in minimal form.
+		if ret.tag < 0x1f {
+			err = SyntaxError{"non-minimal tag"}
+			return
+		}
 	}
 	if offset >= len(bytes) {
 		err = SyntaxError{"truncated tag or length"}
diff --git a/libgo/go/encoding/asn1/asn1_test.go b/libgo/go/encoding/asn1/asn1_test.go
index e0e833123b1..f8623fa9a21 100644
--- a/libgo/go/encoding/asn1/asn1_test.go
+++ b/libgo/go/encoding/asn1/asn1_test.go
@@ -364,7 +364,7 @@ var tagAndLengthData = []tagAndLengthTest{
 	{[]byte{0xa0, 0x01}, true, tagAndLength{2, 0, 1, true}},
 	{[]byte{0x02, 0x00}, true, tagAndLength{0, 2, 0, false}},
 	{[]byte{0xfe, 0x00}, true, tagAndLength{3, 30, 0, true}},
-	{[]byte{0x1f, 0x01, 0x00}, true, tagAndLength{0, 1, 0, false}},
+	{[]byte{0x1f, 0x1f, 0x00}, true, tagAndLength{0, 31, 0, false}},
 	{[]byte{0x1f, 0x81, 0x00, 0x00}, true, tagAndLength{0, 128, 0, false}},
 	{[]byte{0x1f, 0x81, 0x80, 0x01, 0x00}, true, tagAndLength{0, 0x4001, 0, false}},
 	{[]byte{0x00, 0x81, 0x80}, true, tagAndLength{0, 0, 128, false}},
@@ -382,6 +382,8 @@ var tagAndLengthData = []tagAndLengthTest{
 	{[]byte{0xa0, 0x81, 0x7f}, false, tagAndLength{}},
 	// Tag numbers which would overflow int32 are rejected. (The value below is 2^31.)
 	{[]byte{0x1f, 0x88, 0x80, 0x80, 0x80, 0x00, 0x00}, false, tagAndLength{}},
+	// Long tag number form may not be used for tags that fit in short form.
+	{[]byte{0x1f, 0x1e, 0x00}, false, tagAndLength{}},
 }
 
 func TestParseTagAndLength(t *testing.T) {
diff --git a/libgo/go/encoding/asn1/marshal.go b/libgo/go/encoding/asn1/marshal.go
index 6e858584a67..30797ef0996 100644
--- a/libgo/go/encoding/asn1/marshal.go
+++ b/libgo/go/encoding/asn1/marshal.go
@@ -17,7 +17,7 @@ import (
 
 // A forkableWriter is an in-memory buffer that can be
 // 'forked' to create new forkableWriters that bracket the
-// original.  After
+// original. After
 //    pre, post := w.fork()
 // the overall sequence of bytes represented is logically w+pre+post.
 type forkableWriter struct {
@@ -315,9 +315,9 @@ func marshalUTCTime(out *forkableWriter, t time.Time) (err error) {
 
 	switch {
 	case 1950 <= year && year < 2000:
-		err = marshalTwoDigits(out, int(year-1900))
+		err = marshalTwoDigits(out, year-1900)
 	case 2000 <= year && year < 2050:
-		err = marshalTwoDigits(out, int(year-2000))
+		err = marshalTwoDigits(out, year-2000)
 	default:
 		return StructuralError{"cannot represent time as UTCTime"}
 	}
@@ -435,7 +435,7 @@ func marshalBody(out *forkableWriter, value reflect.Value, params fieldParameter
 			return out.WriteByte(0)
 		}
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		return marshalInt64(out, int64(v.Int()))
+		return marshalInt64(out, v.Int())
 	case reflect.Struct:
 		t := v.Type()
 
diff --git a/libgo/go/encoding/base32/base32.go b/libgo/go/encoding/base32/base32.go
index 5a9e86919d8..c193e65e1bc 100644
--- a/libgo/go/encoding/base32/base32.go
+++ b/libgo/go/encoding/base32/base32.go
@@ -17,7 +17,7 @@ import (
  */
 
 // An Encoding is a radix 32 encoding/decoding scheme, defined by a
-// 32-character alphabet.  The most common is the "base32" encoding
+// 32-character alphabet. The most common is the "base32" encoding
 // introduced for SASL GSSAPI and standardized in RFC 4648.
 // The alternate "base32hex" encoding is used in DNSSEC.
 type Encoding struct {
@@ -66,7 +66,7 @@ var removeNewlinesMapper = func(r rune) rune {
 //
 // The encoding pads the output to a multiple of 8 bytes,
 // so Encode is not appropriate for use on individual blocks
-// of a large data stream.  Use NewEncoder() instead.
+// of a large data stream. Use NewEncoder() instead.
 func (enc *Encoding) Encode(dst, src []byte) {
 	if len(src) == 0 {
 		return
@@ -208,7 +208,7 @@ func (e *encoder) Close() error {
 	return e.err
 }
 
-// NewEncoder returns a new base32 stream encoder.  Data written to
+// NewEncoder returns a new base32 stream encoder. Data written to
 // the returned writer will be encoded using enc and then written to w.
 // Base32 encodings operate in 5-byte blocks; when finished
 // writing, the caller must Close the returned encoder to flush any
@@ -313,9 +313,9 @@ func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
 	return n, end, nil
 }
 
-// Decode decodes src using the encoding enc.  It writes at most
+// Decode decodes src using the encoding enc. It writes at most
 // DecodedLen(len(src)) bytes to dst and returns the number of bytes
-// written.  If src contains invalid base32 data, it will return the
+// written. If src contains invalid base32 data, it will return the
 // number of bytes successfully written and CorruptInputError.
 // New line characters (\r and \n) are ignored.
 func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
diff --git a/libgo/go/encoding/base32/base32_test.go b/libgo/go/encoding/base32/base32_test.go
index 5a68f06e1c9..66a48a3f6f7 100644
--- a/libgo/go/encoding/base32/base32_test.go
+++ b/libgo/go/encoding/base32/base32_test.go
@@ -171,7 +171,7 @@ func TestDecodeCorrupt(t *testing.T) {
 		_, err := StdEncoding.Decode(dbuf, []byte(tc.input))
 		if tc.offset == -1 {
 			if err != nil {
-				t.Error("Decoder wrongly detected coruption in", tc.input)
+				t.Error("Decoder wrongly detected corruption in", tc.input)
 			}
 			continue
 		}
diff --git a/libgo/go/encoding/base64/base64.go b/libgo/go/encoding/base64/base64.go
index 1bda804c38a..c2116d8a343 100644
--- a/libgo/go/encoding/base64/base64.go
+++ b/libgo/go/encoding/base64/base64.go
@@ -15,7 +15,7 @@ import (
  */
 
 // An Encoding is a radix 64 encoding/decoding scheme, defined by a
-// 64-character alphabet.  The most common encoding is the "base64"
+// 64-character alphabet. The most common encoding is the "base64"
 // encoding defined in RFC 4648 and used in MIME (RFC 2045) and PEM
 // (RFC 1421).  RFC 4648 also defines an alternate encoding, which is
 // the standard encoding with - and _ substituted for + and /.
@@ -89,7 +89,7 @@ var RawURLEncoding = URLEncoding.WithPadding(NoPadding)
 //
 // The encoding pads the output to a multiple of 4 bytes,
 // so Encode is not appropriate for use on individual blocks
-// of a large data stream.  Use NewEncoder() instead.
+// of a large data stream. Use NewEncoder() instead.
 func (enc *Encoding) Encode(dst, src []byte) {
 	if len(src) == 0 {
 		return
@@ -213,7 +213,7 @@ func (e *encoder) Close() error {
 	return e.err
 }
 
-// NewEncoder returns a new base64 stream encoder.  Data written to
+// NewEncoder returns a new base64 stream encoder. Data written to
 // the returned writer will be encoded using enc and then written to w.
 // Base64 encodings operate in 4-byte blocks; when finished
 // writing, the caller must Close the returned encoder to flush any
@@ -328,9 +328,9 @@ func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
 	return n, end, err
 }
 
-// Decode decodes src using the encoding enc.  It writes at most
+// Decode decodes src using the encoding enc. It writes at most
 // DecodedLen(len(src)) bytes to dst and returns the number of bytes
-// written.  If src contains invalid base64 data, it will return the
+// written. If src contains invalid base64 data, it will return the
 // number of bytes successfully written and CorruptInputError.
 // New line characters (\r and \n) are ignored.
 func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
@@ -459,7 +459,7 @@ func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
 func (enc *Encoding) DecodedLen(n int) int {
 	if enc.padChar == NoPadding {
 		// Unpadded data may end with partial block of 2-3 characters.
-		return (n*6 + 7) / 8
+		return n * 6 / 8
 	}
 	// Padded base64 should always be a multiple of 4 characters in length.
 	return n / 4 * 3
diff --git a/libgo/go/encoding/base64/base64_test.go b/libgo/go/encoding/base64/base64_test.go
index fc6a1ea654f..19ddb92f644 100644
--- a/libgo/go/encoding/base64/base64_test.go
+++ b/libgo/go/encoding/base64/base64_test.go
@@ -221,7 +221,7 @@ func TestDecodeCorrupt(t *testing.T) {
 		_, err := StdEncoding.Decode(dbuf, []byte(tc.input))
 		if tc.offset == -1 {
 			if err != nil {
-				t.Error("Decoder wrongly detected coruption in", tc.input)
+				t.Error("Decoder wrongly detected corruption in", tc.input)
 			}
 			continue
 		}
@@ -234,6 +234,51 @@ func TestDecodeCorrupt(t *testing.T) {
 	}
 }
 
+func TestEncodedLen(t *testing.T) {
+	for _, tt := range []struct {
+		enc  *Encoding
+		n    int
+		want int
+	}{
+		{RawStdEncoding, 0, 0},
+		{RawStdEncoding, 1, 2},
+		{RawStdEncoding, 2, 3},
+		{RawStdEncoding, 3, 4},
+		{RawStdEncoding, 7, 10},
+		{StdEncoding, 0, 0},
+		{StdEncoding, 1, 4},
+		{StdEncoding, 2, 4},
+		{StdEncoding, 3, 4},
+		{StdEncoding, 4, 8},
+		{StdEncoding, 7, 12},
+	} {
+		if got := tt.enc.EncodedLen(tt.n); got != tt.want {
+			t.Errorf("EncodedLen(%d): got %d, want %d", tt.n, got, tt.want)
+		}
+	}
+}
+
+func TestDecodedLen(t *testing.T) {
+	for _, tt := range []struct {
+		enc  *Encoding
+		n    int
+		want int
+	}{
+		{RawStdEncoding, 0, 0},
+		{RawStdEncoding, 2, 1},
+		{RawStdEncoding, 3, 2},
+		{RawStdEncoding, 4, 3},
+		{RawStdEncoding, 10, 7},
+		{StdEncoding, 0, 0},
+		{StdEncoding, 4, 3},
+		{StdEncoding, 8, 6},
+	} {
+		if got := tt.enc.DecodedLen(tt.n); got != tt.want {
+			t.Errorf("DecodedLen(%d): got %d, want %d", tt.n, got, tt.want)
+		}
+	}
+}
+
 func TestBig(t *testing.T) {
 	n := 3*1000 + 1
 	raw := make([]byte, n)
diff --git a/libgo/go/encoding/binary/binary.go b/libgo/go/encoding/binary/binary.go
index 1c2577b68de..46c6add062a 100644
--- a/libgo/go/encoding/binary/binary.go
+++ b/libgo/go/encoding/binary/binary.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -48,18 +48,24 @@ var BigEndian bigEndian
 
 type littleEndian struct{}
 
-func (littleEndian) Uint16(b []byte) uint16 { return uint16(b[0]) | uint16(b[1])<<8 }
+func (littleEndian) Uint16(b []byte) uint16 {
+	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint16(b[0]) | uint16(b[1])<<8
+}
 
 func (littleEndian) PutUint16(b []byte, v uint16) {
+	_ = b[1] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v)
 	b[1] = byte(v >> 8)
 }
 
 func (littleEndian) Uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
 }
 
 func (littleEndian) PutUint32(b []byte, v uint32) {
+	_ = b[3] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v)
 	b[1] = byte(v >> 8)
 	b[2] = byte(v >> 16)
@@ -67,11 +73,13 @@ func (littleEndian) PutUint32(b []byte, v uint32) {
 }
 
 func (littleEndian) Uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
 		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
 }
 
 func (littleEndian) PutUint64(b []byte, v uint64) {
+	_ = b[7] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v)
 	b[1] = byte(v >> 8)
 	b[2] = byte(v >> 16)
@@ -88,18 +96,24 @@ func (littleEndian) GoString() string { return "binary.LittleEndian" }
 
 type bigEndian struct{}
 
-func (bigEndian) Uint16(b []byte) uint16 { return uint16(b[1]) | uint16(b[0])<<8 }
+func (bigEndian) Uint16(b []byte) uint16 {
+	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint16(b[1]) | uint16(b[0])<<8
+}
 
 func (bigEndian) PutUint16(b []byte, v uint16) {
+	_ = b[1] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v >> 8)
 	b[1] = byte(v)
 }
 
 func (bigEndian) Uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
 }
 
 func (bigEndian) PutUint32(b []byte, v uint32) {
+	_ = b[3] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v >> 24)
 	b[1] = byte(v >> 16)
 	b[2] = byte(v >> 8)
@@ -107,11 +121,13 @@ func (bigEndian) PutUint32(b []byte, v uint32) {
 }
 
 func (bigEndian) Uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
 	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
 		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
 }
 
 func (bigEndian) PutUint64(b []byte, v uint64) {
+	_ = b[7] // early bounds check to guarantee safety of writes below
 	b[0] = byte(v >> 56)
 	b[1] = byte(v >> 48)
 	b[2] = byte(v >> 40)
@@ -253,7 +269,7 @@ func Write(w io.Writer, order ByteOrder, data interface{}) error {
 		case *uint8:
 			b[0] = *v
 		case uint8:
-			b[0] = byte(v)
+			b[0] = v
 		case []uint8:
 			bs = v
 		case *int16:
diff --git a/libgo/go/encoding/binary/binary_test.go b/libgo/go/encoding/binary/binary_test.go
index 7fd36fa4efa..c0728e943e8 100644
--- a/libgo/go/encoding/binary/binary_test.go
+++ b/libgo/go/encoding/binary/binary_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -266,7 +266,7 @@ func TestBlankFields(t *testing.T) {
 }
 
 // An attempt to read into a struct with an unexported field will
-// panic.  This is probably not the best choice, but at this point
+// panic. This is probably not the best choice, but at this point
 // anything else would be an API change.
 
 type Unexported struct {
@@ -339,6 +339,33 @@ func TestReadTruncated(t *testing.T) {
 	}
 }
 
+func testUint64SmallSliceLengthPanics() (panicked bool) {
+	defer func() {
+		panicked = recover() != nil
+	}()
+	b := [8]byte{1, 2, 3, 4, 5, 6, 7, 8}
+	LittleEndian.Uint64(b[:4])
+	return false
+}
+
+func testPutUint64SmallSliceLengthPanics() (panicked bool) {
+	defer func() {
+		panicked = recover() != nil
+	}()
+	b := [8]byte{}
+	LittleEndian.PutUint64(b[:4], 0x0102030405060708)
+	return false
+}
+
+func TestEarlyBoundsChecks(t *testing.T) {
+	if testUint64SmallSliceLengthPanics() != true {
+		t.Errorf("binary.LittleEndian.Uint64 expected to panic for small slices, but didn't")
+	}
+	if testPutUint64SmallSliceLengthPanics() != true {
+		t.Errorf("binary.LittleEndian.PutUint64 expected to panic for small slices, but didn't")
+	}
+}
+
 type byteSliceReader struct {
 	remain []byte
 }
@@ -373,8 +400,8 @@ func BenchmarkReadStruct(b *testing.B) {
 		Read(bsr, BigEndian, &t)
 	}
 	b.StopTimer()
-	if !reflect.DeepEqual(s, t) {
-		b.Fatal("no match")
+	if b.N > 0 && !reflect.DeepEqual(s, t) {
+		b.Fatalf("struct doesn't match:\ngot  %v;\nwant %v", t, s)
 	}
 }
 
@@ -405,8 +432,8 @@ func BenchmarkReadInts(b *testing.B) {
 		want.Array[i] = 0
 	}
 	b.StopTimer()
-	if !reflect.DeepEqual(ls, want) {
-		panic("no match")
+	if b.N > 0 && !reflect.DeepEqual(ls, want) {
+		b.Fatalf("struct doesn't match:\ngot  %v;\nwant %v", ls, want)
 	}
 }
 
@@ -427,7 +454,7 @@ func BenchmarkWriteInts(b *testing.B) {
 		Write(w, BigEndian, s.Uint64)
 	}
 	b.StopTimer()
-	if !bytes.Equal(buf.Bytes(), big[:30]) {
+	if b.N > 0 && !bytes.Equal(buf.Bytes(), big[:30]) {
 		b.Fatalf("first half doesn't match: %x %x", buf.Bytes(), big[:30])
 	}
 }
diff --git a/libgo/go/encoding/binary/varint.go b/libgo/go/encoding/binary/varint.go
index 3a2dfa3c74e..d7a75f99b16 100644
--- a/libgo/go/encoding/binary/varint.go
+++ b/libgo/go/encoding/binary/varint.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/csv/reader.go b/libgo/go/encoding/csv/reader.go
index a6bb780bf28..a5e03a9f8ef 100644
--- a/libgo/go/encoding/csv/reader.go
+++ b/libgo/go/encoding/csv/reader.go
@@ -3,6 +3,8 @@
 // license that can be found in the LICENSE file.
 
 // Package csv reads and writes comma-separated values (CSV) files.
+// There are many kinds of CSV files; this package supports the format
+// described in RFC 4180.
 //
 // A csv file contains zero or more records of one or more fields per record.
 // Each record is separated by the newline character. The final record may
@@ -14,11 +16,11 @@
 //
 // Carriage returns before newline characters are silently removed.
 //
-// Blank lines are ignored.  A line with only whitespace characters (excluding
+// Blank lines are ignored. A line with only whitespace characters (excluding
 // the ending newline character) is not considered a blank line.
 //
 // Fields which start and stop with the quote character " are called
-// quoted-fields.  The beginning and ending quote are not part of the
+// quoted-fields. The beginning and ending quote are not part of the
 // field.
 //
 // The source:
@@ -84,32 +86,35 @@ var (
 // The exported fields can be changed to customize the details before the
 // first call to Read or ReadAll.
 //
-// Comma is the field delimiter.  It defaults to ','.
 //
-// Comment, if not 0, is the comment character. Lines beginning with the
-// Comment character are ignored.
-//
-// If FieldsPerRecord is positive, Read requires each record to
-// have the given number of fields.  If FieldsPerRecord is 0, Read sets it to
-// the number of fields in the first record, so that future records must
-// have the same field count.  If FieldsPerRecord is negative, no check is
-// made and records may have a variable number of fields.
-//
-// If LazyQuotes is true, a quote may appear in an unquoted field and a
-// non-doubled quote may appear in a quoted field.
-//
-// If TrimLeadingSpace is true, leading white space in a field is ignored.
 type Reader struct {
-	Comma            rune // field delimiter (set to ',' by NewReader)
-	Comment          rune // comment character for start of line
-	FieldsPerRecord  int  // number of expected fields per record
-	LazyQuotes       bool // allow lazy quotes
-	TrailingComma    bool // ignored; here for backwards compatibility
-	TrimLeadingSpace bool // trim leading space
-	line             int
-	column           int
-	r                *bufio.Reader
-	field            bytes.Buffer
+	// Comma is the field delimiter.
+	// It is set to comma (',') by NewReader.
+	Comma rune
+	// Comment, if not 0, is the comment character. Lines beginning with the
+	// Comment character without preceding whitespace are ignored.
+	// With leading whitespace the Comment character becomes part of the
+	// field, even if TrimLeadingSpace is true.
+	Comment rune
+	// FieldsPerRecord is the number of expected fields per record.
+	// If FieldsPerRecord is positive, Read requires each record to
+	// have the given number of fields. If FieldsPerRecord is 0, Read sets it to
+	// the number of fields in the first record, so that future records must
+	// have the same field count. If FieldsPerRecord is negative, no check is
+	// made and records may have a variable number of fields.
+	FieldsPerRecord int
+	// If LazyQuotes is true, a quote may appear in an unquoted field and a
+	// non-doubled quote may appear in a quoted field.
+	LazyQuotes    bool
+	TrailingComma bool // ignored; here for backwards compatibility
+	// If TrimLeadingSpace is true, leading white space in a field is ignored.
+	// This is done even if the field delimiter, Comma, is white space.
+	TrimLeadingSpace bool
+
+	line   int
+	column int
+	r      *bufio.Reader
+	field  bytes.Buffer
 }
 
 // NewReader returns a new Reader that reads from r.
@@ -129,7 +134,7 @@ func (r *Reader) error(err error) error {
 	}
 }
 
-// Read reads one record from r.  The record is a slice of strings with each
+// Read reads one record from r. The record is a slice of strings with each
 // string representing one field.
 func (r *Reader) Read() (record []string, err error) {
 	for {
@@ -177,7 +182,7 @@ func (r *Reader) ReadAll() (records [][]string, err error) {
 func (r *Reader) readRune() (rune, error) {
 	r1, _, err := r.r.ReadRune()
 
-	// Handle \r\n here.  We make the simplifying assumption that
+	// Handle \r\n here. We make the simplifying assumption that
 	// anytime \r is followed by \n that it can be folded to \n.
 	// We will not detect files which contain both \r\n and bare \n.
 	if r1 == '\r' {
@@ -208,13 +213,13 @@ func (r *Reader) skip(delim rune) error {
 
 // parseRecord reads and parses a single csv record from r.
 func (r *Reader) parseRecord() (fields []string, err error) {
-	// Each record starts on a new line.  We increment our line
+	// Each record starts on a new line. We increment our line
 	// number (lines start at 1, not 0) and set column to -1
 	// so as we increment in readRune it points to the character we read.
 	r.line++
 	r.column = -1
 
-	// Peek at the first rune.  If it is an error we are done.
+	// Peek at the first rune. If it is an error we are done.
 	// If we support comments and it is the comment character
 	// then skip to the end of line.
 
@@ -232,7 +237,7 @@ func (r *Reader) parseRecord() (fields []string, err error) {
 	for {
 		haveField, delim, err := r.parseField()
 		if haveField {
-			// If FieldsPerRecord is greater then 0 we can assume the final
+			// If FieldsPerRecord is greater than 0 we can assume the final
 			// length of fields to be equal to FieldsPerRecord.
 			if r.FieldsPerRecord > 0 && fields == nil {
 				fields = make([]string, 0, r.FieldsPerRecord)
@@ -247,8 +252,8 @@ func (r *Reader) parseRecord() (fields []string, err error) {
 	}
 }
 
-// parseField parses the next field in the record.  The read field is
-// located in r.field.  Delim is the first character not part of the field
+// parseField parses the next field in the record. The read field is
+// located in r.field. Delim is the first character not part of the field
 // (r.Comma or '\n').
 func (r *Reader) parseField() (haveField bool, delim rune, err error) {
 	r.field.Reset()
diff --git a/libgo/go/encoding/csv/writer.go b/libgo/go/encoding/csv/writer.go
index 353d91f238f..84b7aa1ed10 100644
--- a/libgo/go/encoding/csv/writer.go
+++ b/libgo/go/encoding/csv/writer.go
@@ -15,7 +15,7 @@ import (
 // A Writer writes records to a CSV encoded file.
 //
 // As returned by NewWriter, a Writer writes records terminated by a
-// newline and uses ',' as the field delimiter.  The exported fields can be
+// newline and uses ',' as the field delimiter. The exported fields can be
 // changed to customize the details before the first call to Write or WriteAll.
 //
 // Comma is the field delimiter.
@@ -37,27 +37,28 @@ func NewWriter(w io.Writer) *Writer {
 
 // Writer writes a single CSV record to w along with any necessary quoting.
 // A record is a slice of strings with each string being one field.
-func (w *Writer) Write(record []string) (err error) {
+func (w *Writer) Write(record []string) error {
 	for n, field := range record {
 		if n > 0 {
-			if _, err = w.w.WriteRune(w.Comma); err != nil {
-				return
+			if _, err := w.w.WriteRune(w.Comma); err != nil {
+				return err
 			}
 		}
 
 		// If we don't have to have a quoted field then just
 		// write out the field and continue to the next field.
 		if !w.fieldNeedsQuotes(field) {
-			if _, err = w.w.WriteString(field); err != nil {
-				return
+			if _, err := w.w.WriteString(field); err != nil {
+				return err
 			}
 			continue
 		}
-		if err = w.w.WriteByte('"'); err != nil {
-			return
+		if err := w.w.WriteByte('"'); err != nil {
+			return err
 		}
 
 		for _, r1 := range field {
+			var err error
 			switch r1 {
 			case '"':
 				_, err = w.w.WriteString(`""`)
@@ -75,20 +76,21 @@ func (w *Writer) Write(record []string) (err error) {
 				_, err = w.w.WriteRune(r1)
 			}
 			if err != nil {
-				return
+				return err
 			}
 		}
 
-		if err = w.w.WriteByte('"'); err != nil {
-			return
+		if err := w.w.WriteByte('"'); err != nil {
+			return err
 		}
 	}
+	var err error
 	if w.UseCRLF {
 		_, err = w.w.WriteString("\r\n")
 	} else {
 		err = w.w.WriteByte('\n')
 	}
-	return
+	return err
 }
 
 // Flush writes any buffered data to the underlying io.Writer.
@@ -104,9 +106,9 @@ func (w *Writer) Error() error {
 }
 
 // WriteAll writes multiple CSV records to w using Write and then calls Flush.
-func (w *Writer) WriteAll(records [][]string) (err error) {
+func (w *Writer) WriteAll(records [][]string) error {
 	for _, record := range records {
-		err = w.Write(record)
+		err := w.Write(record)
 		if err != nil {
 			return err
 		}
@@ -130,7 +132,7 @@ func (w *Writer) fieldNeedsQuotes(field string) bool {
 	if field == "" {
 		return false
 	}
-	if field == `\.` || strings.IndexRune(field, w.Comma) >= 0 || strings.IndexAny(field, "\"\r\n") >= 0 {
+	if field == `\.` || strings.ContainsRune(field, w.Comma) || strings.ContainsAny(field, "\"\r\n") {
 		return true
 	}
 
diff --git a/libgo/go/encoding/encoding.go b/libgo/go/encoding/encoding.go
index 6d218071b7a..cc5a5369966 100644
--- a/libgo/go/encoding/encoding.go
+++ b/libgo/go/encoding/encoding.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/gob/codec_test.go b/libgo/go/encoding/gob/codec_test.go
index 8efcdc78fff..d4002cbccab 100644
--- a/libgo/go/encoding/gob/codec_test.go
+++ b/libgo/go/encoding/gob/codec_test.go
@@ -970,7 +970,7 @@ func TestBadRecursiveType(t *testing.T) {
 	err := NewEncoder(b).Encode(&rec)
 	if err == nil {
 		t.Error("expected error; got none")
-	} else if strings.Index(err.Error(), "recursive") < 0 {
+	} else if !strings.Contains(err.Error(), "recursive") {
 		t.Error("expected recursive type error; got", err)
 	}
 	// Can't test decode easily because we can't encode one, so we can't pass one to a Decoder.
@@ -1253,7 +1253,7 @@ func TestIgnoreInterface(t *testing.T) {
 	if item2.I != item1.I {
 		t.Error("normal int did not decode correctly")
 	}
-	if item2.F != item2.F {
+	if item2.F != item1.F {
 		t.Error("normal float did not decode correctly")
 	}
 }
@@ -1280,7 +1280,7 @@ func TestUnexportedFields(t *testing.T) {
 	if err != nil {
 		t.Fatal("decode error:", err)
 	}
-	if u0.A != u0.A || u0.B != u1.B || u0.D != u1.D {
+	if u0.A != u1.A || u0.B != u1.B || u0.D != u1.D {
 		t.Errorf("u1->u0: expected %v; got %v", u0, u1)
 	}
 	if u1.c != 1234. {
diff --git a/libgo/go/encoding/gob/debug.go b/libgo/go/encoding/gob/debug.go
index 536bbdb5ac6..d69d36f5164 100644
--- a/libgo/go/encoding/gob/debug.go
+++ b/libgo/go/encoding/gob/debug.go
@@ -7,7 +7,7 @@
 
 package gob
 
-// This file is not normally included in the gob package.  Used only for debugging the package itself.
+// This file is not normally included in the gob package. Used only for debugging the package itself.
 // Except for reading uints, it is an implementation of a reader that is independent of
 // the one implemented by Decoder.
 // To enable the Debug function, delete the +build ignore line above and do
@@ -241,7 +241,7 @@ func (deb *debugger) delimitedMessage(indent tab) bool {
 // loadBlock preps us to read a message
 // of the length specified next in the input. It returns
 // the length of the block. The argument tells whether
-// an EOF is acceptable now.  If it is and one is found,
+// an EOF is acceptable now. If it is and one is found,
 // the return value is negative.
 func (deb *debugger) loadBlock(eofOK bool) int {
 	n64, w, err := decodeUintReader(deb.r, deb.tmp) // deb.uint64 will error at EOF
@@ -339,7 +339,7 @@ func (deb *debugger) string() string {
 	return string(b)
 }
 
-// delta returns the field delta at the input point.  The expect argument,
+// delta returns the field delta at the input point. The expect argument,
 // if non-negative, identifies what the value should be.
 func (deb *debugger) delta(expect int) int {
 	delta := int(deb.uint64())
diff --git a/libgo/go/encoding/gob/decode.go b/libgo/go/encoding/gob/decode.go
index 3b0dca86f34..9645dc57906 100644
--- a/libgo/go/encoding/gob/decode.go
+++ b/libgo/go/encoding/gob/decode.go
@@ -216,10 +216,10 @@ func ignoreTwoUints(i *decInstr, state *decoderState, v reflect.Value) {
 }
 
 // Since the encoder writes no zeros, if we arrive at a decoder we have
-// a value to extract and store.  The field number has already been read
+// a value to extract and store. The field number has already been read
 // (it's how we knew to call this decoder).
 // Each decoder is responsible for handling any indirections associated
-// with the data structure.  If any pointer so reached is nil, allocation must
+// with the data structure. If any pointer so reached is nil, allocation must
 // be done.
 
 // decAlloc takes a value and returns a settable value that can
@@ -308,9 +308,9 @@ func decUint64(i *decInstr, state *decoderState, value reflect.Value) {
 }
 
 // Floating-point numbers are transmitted as uint64s holding the bits
-// of the underlying representation.  They are sent byte-reversed, with
+// of the underlying representation. They are sent byte-reversed, with
 // the exponent end coming out first, so integer floating point numbers
-// (for example) transmit more compactly.  This routine does the
+// (for example) transmit more compactly. This routine does the
 // unswizzling.
 func float64FromBits(u uint64) float64 {
 	var v uint64
@@ -332,7 +332,7 @@ func float32FromBits(u uint64, ovfl error) float64 {
 	if av < 0 {
 		av = -av
 	}
-	// +Inf is OK in both 32- and 64-bit floats.  Underflow is always OK.
+	// +Inf is OK in both 32- and 64-bit floats. Underflow is always OK.
 	if math.MaxFloat32 < av && av <= math.MaxFloat64 {
 		error_(ovfl)
 	}
@@ -421,7 +421,7 @@ func ignoreUint8Array(i *decInstr, state *decoderState, value reflect.Value) {
 // Execution engine
 
 // The encoder engine is an array of instructions indexed by field number of the incoming
-// decoder.  It is executed with random access according to field number.
+// decoder. It is executed with random access according to field number.
 type decEngine struct {
 	instr    []decInstr
 	numInstr int // the number of active instructions
@@ -442,7 +442,7 @@ func (dec *Decoder) decodeSingle(engine *decEngine, ut *userTypeInfo, value refl
 }
 
 // decodeStruct decodes a top-level struct and stores it in value.
-// Indir is for the value, not the type.  At the time of the call it may
+// Indir is for the value, not the type. At the time of the call it may
 // differ from ut.indir, which was computed when the engine was built.
 // This state cannot arise for decodeSingle, which is called directly
 // from the user's value, not from the innards of an engine.
@@ -536,7 +536,7 @@ func (dec *Decoder) decodeArrayHelper(state *decoderState, value reflect.Value,
 }
 
 // decodeArray decodes an array and stores it in value.
-// The length is an unsigned integer preceding the elements.  Even though the length is redundant
+// The length is an unsigned integer preceding the elements. Even though the length is redundant
 // (it's part of the type), it's a useful check and is included in the encoding.
 func (dec *Decoder) decodeArray(atyp reflect.Type, state *decoderState, value reflect.Value, elemOp decOp, length int, ovfl error, helper decHelper) {
 	if n := state.decodeUint(); n != uint64(length) {
@@ -645,10 +645,10 @@ func (dec *Decoder) decodeInterface(ityp reflect.Type, state *decoderState, valu
 		errorf("invalid type name length %d: exceeds input size", nr)
 	}
 	n := int(nr)
-	name := string(state.b.Bytes()[:n])
+	name := state.b.Bytes()[:n]
 	state.b.Drop(n)
 	// Allocate the destination interface value.
-	if name == "" {
+	if len(name) == 0 {
 		// Copy the nil interface value to the target.
 		value.Set(reflect.Zero(value.Type()))
 		return
@@ -658,7 +658,7 @@ func (dec *Decoder) decodeInterface(ityp reflect.Type, state *decoderState, valu
 	}
 	// The concrete type must be registered.
 	registerLock.RLock()
-	typ, ok := nameToConcreteType[name]
+	typ, ok := nameToConcreteType[string(name)]
 	registerLock.RUnlock()
 	if !ok {
 		errorf("name not registered for interface: %q", name)
@@ -1075,7 +1075,7 @@ func (dec *Decoder) compileIgnoreSingle(remoteId typeId) (engine *decEngine, err
 	return
 }
 
-// compileDec compiles the decoder engine for a value.  If the value is not a struct,
+// compileDec compiles the decoder engine for a value. If the value is not a struct,
 // it calls out to compileSingle.
 func (dec *Decoder) compileDec(remoteId typeId, ut *userTypeInfo) (engine *decEngine, err error) {
 	defer catchError(&err)
diff --git a/libgo/go/encoding/gob/decoder.go b/libgo/go/encoding/gob/decoder.go
index c453e9ba397..c1829417733 100644
--- a/libgo/go/encoding/gob/decoder.go
+++ b/libgo/go/encoding/gob/decoder.go
@@ -130,9 +130,9 @@ func (dec *Decoder) nextUint() uint64 {
 // decodeTypeSequence parses:
 // TypeSequence
 //	(TypeDefinition DelimitedTypeDefinition*)?
-// and returns the type id of the next value.  It returns -1 at
+// and returns the type id of the next value. It returns -1 at
 // EOF.  Upon return, the remainder of dec.buf is the value to be
-// decoded.  If this is an interface value, it can be ignored by
+// decoded. If this is an interface value, it can be ignored by
 // resetting that buffer.
 func (dec *Decoder) decodeTypeSequence(isInterface bool) typeId {
 	for dec.err == nil {
@@ -150,7 +150,7 @@ func (dec *Decoder) decodeTypeSequence(isInterface bool) typeId {
 		// Type definition for (-id) follows.
 		dec.recvType(-id)
 		// When decoding an interface, after a type there may be a
-		// DelimitedValue still in the buffer.  Skip its count.
+		// DelimitedValue still in the buffer. Skip its count.
 		// (Alternatively, the buffer is empty and the byte count
 		// will be absorbed by recvMessage.)
 		if dec.buf.Len() > 0 {
@@ -177,7 +177,7 @@ func (dec *Decoder) Decode(e interface{}) error {
 	}
 	value := reflect.ValueOf(e)
 	// If e represents a value as opposed to a pointer, the answer won't
-	// get back to the caller.  Make sure it's a pointer.
+	// get back to the caller. Make sure it's a pointer.
 	if value.Type().Kind() != reflect.Ptr {
 		dec.err = errors.New("gob: attempt to decode into a non-pointer")
 		return dec.err
@@ -187,7 +187,7 @@ func (dec *Decoder) Decode(e interface{}) error {
 
 // DecodeValue reads the next value from the input stream.
 // If v is the zero reflect.Value (v.Kind() == Invalid), DecodeValue discards the value.
-// Otherwise, it stores the value into v.  In that case, v must represent
+// Otherwise, it stores the value into v. In that case, v must represent
 // a non-nil pointer to data or be an assignable reflect.Value (v.CanSet())
 // If the input is at EOF, DecodeValue returns io.EOF and
 // does not modify v.
diff --git a/libgo/go/encoding/gob/doc.go b/libgo/go/encoding/gob/doc.go
index cf878f45029..1536574fed2 100644
--- a/libgo/go/encoding/gob/doc.go
+++ b/libgo/go/encoding/gob/doc.go
@@ -17,7 +17,8 @@ Basics
 A stream of gobs is self-describing.  Each data item in the stream is preceded by
 a specification of its type, expressed in terms of a small set of predefined
 types.  Pointers are not transmitted, but the things they point to are
-transmitted; that is, the values are flattened.  Recursive types work fine, but
+transmitted; that is, the values are flattened. Nil pointers are not permitted,
+as they have no value. Recursive types work fine, but
 recursive values (data with cycles) are problematic.  This may change.
 
 To use gobs, create an Encoder and present it with a series of data items as
@@ -254,6 +255,12 @@ In summary, a gob stream looks like
 where * signifies zero or more repetitions and the type id of a value must
 be predefined or be defined before the value in the stream.
 
+Compatibility: Any future changes to the package will endeavor to maintain
+compatibility with streams encoded using previous versions.  That is, any released
+version of this package should be able to decode data written with any previously
+released version, subject to issues such as security fixes. See the Go compatibility
+document for background: https://golang.org/doc/go1compat
+
 See "Gobs of data" for a design discussion of the gob wire format:
 https://blog.golang.org/gobs-of-data
 */
diff --git a/libgo/go/encoding/gob/encode.go b/libgo/go/encoding/gob/encode.go
index 96052ef33b6..50cd6adb463 100644
--- a/libgo/go/encoding/gob/encode.go
+++ b/libgo/go/encoding/gob/encode.go
@@ -96,7 +96,7 @@ func (enc *Encoder) freeEncoderState(e *encoderState) {
 	enc.freeList = e
 }
 
-// Unsigned integers have a two-state encoding.  If the number is less
+// Unsigned integers have a two-state encoding. If the number is less
 // than 128 (0 through 0x7F), its value is written directly.
 // Otherwise the value is written in big-endian byte order preceded
 // by the byte length, negated.
@@ -127,7 +127,7 @@ func (state *encoderState) encodeInt(i int64) {
 	} else {
 		x = uint64(i << 1)
 	}
-	state.encodeUint(uint64(x))
+	state.encodeUint(x)
 }
 
 // encOp is the signature of an encoding operator for a given type.
@@ -152,8 +152,8 @@ func (state *encoderState) update(instr *encInstr) {
 
 // Each encoder for a composite is responsible for handling any
 // indirections associated with the elements of the data structure.
-// If any pointer so reached is nil, no bytes are written.  If the
-// data item is zero, no bytes are written.  Single values - ints,
+// If any pointer so reached is nil, no bytes are written. If the
+// data item is zero, no bytes are written. Single values - ints,
 // strings etc. - are indirected before calling their encoders.
 // Otherwise, the output (for a scalar) is the field number, as an
 // encoded integer, followed by the field data in its appropriate
@@ -203,9 +203,9 @@ func encUint(i *encInstr, state *encoderState, v reflect.Value) {
 
 // floatBits returns a uint64 holding the bits of a floating-point number.
 // Floating-point numbers are transmitted as uint64s holding the bits
-// of the underlying representation.  They are sent byte-reversed, with
+// of the underlying representation. They are sent byte-reversed, with
 // the exponent end coming out first, so integer floating point numbers
-// (for example) transmit more compactly.  This routine does the
+// (for example) transmit more compactly. This routine does the
 // swizzling.
 func floatBits(f float64) uint64 {
 	u := math.Float64bits(f)
@@ -272,7 +272,7 @@ func encStructTerminator(i *encInstr, state *encoderState, v reflect.Value) {
 // Execution engine
 
 // encEngine an array of instructions indexed by field number of the encoding
-// data, typically a struct.  It is executed top to bottom, walking the struct.
+// data, typically a struct. It is executed top to bottom, walking the struct.
 type encEngine struct {
 	instr []encInstr
 }
@@ -297,7 +297,7 @@ func (enc *Encoder) encodeSingle(b *encBuffer, engine *encEngine, value reflect.
 	defer enc.freeEncoderState(state)
 	state.fieldnum = singletonField
 	// There is no surrounding struct to frame the transmission, so we must
-	// generate data even if the item is zero.  To do this, set sendZero.
+	// generate data even if the item is zero. To do this, set sendZero.
 	state.sendZero = true
 	instr := &engine.instr[singletonField]
 	if instr.indir > 0 {
@@ -386,7 +386,7 @@ func (enc *Encoder) encodeMap(b *encBuffer, mv reflect.Value, keyOp, elemOp encO
 // encodeInterface encodes the interface value iv.
 // To send an interface, we send a string identifying the concrete type, followed
 // by the type identifier (which might require defining that type right now), followed
-// by the concrete value.  A nil value gets sent as the empty string for the name,
+// by the concrete value. A nil value gets sent as the empty string for the name,
 // followed by no value.
 func (enc *Encoder) encodeInterface(b *encBuffer, iv reflect.Value) {
 	// Gobs can encode nil interface values but not typed interface
@@ -417,7 +417,7 @@ func (enc *Encoder) encodeInterface(b *encBuffer, iv reflect.Value) {
 	enc.sendTypeDescriptor(enc.writer(), state, ut)
 	// Send the type id.
 	enc.sendTypeId(state, ut)
-	// Encode the value into a new buffer.  Any nested type definitions
+	// Encode the value into a new buffer. Any nested type definitions
 	// should be written to b, before the encoded value.
 	enc.pushWriter(b)
 	data := encBufferPool.Get().(*encBuffer)
diff --git a/libgo/go/encoding/gob/encoder.go b/libgo/go/encoding/gob/encoder.go
index 62d0f42e81a..d6c8fdd9630 100644
--- a/libgo/go/encoding/gob/encoder.go
+++ b/libgo/go/encoding/gob/encoder.go
@@ -170,6 +170,7 @@ func (enc *Encoder) sendType(w io.Writer, state *encoderState, origt reflect.Typ
 
 // Encode transmits the data item represented by the empty interface value,
 // guaranteeing that all necessary type information has been transmitted first.
+// Passing a nil pointer to Encoder will panic, as they cannot be transmitted by gob.
 func (enc *Encoder) Encode(e interface{}) error {
 	return enc.EncodeValue(reflect.ValueOf(e))
 }
@@ -191,7 +192,7 @@ func (enc *Encoder) sendTypeDescriptor(w io.Writer, state *encoderState, ut *use
 			return
 		}
 		// If the type info has still not been transmitted, it means we have
-		// a singleton basic type (int, []byte etc.) at top level.  We don't
+		// a singleton basic type (int, []byte etc.) at top level. We don't
 		// need to send the type info but we do need to update enc.sent.
 		if !sent {
 			info, err := getTypeInfo(ut)
@@ -212,9 +213,8 @@ func (enc *Encoder) sendTypeId(state *encoderState, ut *userTypeInfo) {
 
 // EncodeValue transmits the data item represented by the reflection value,
 // guaranteeing that all necessary type information has been transmitted first.
+// Passing a nil pointer to EncodeValue will panic, as they cannot be transmitted by gob.
 func (enc *Encoder) EncodeValue(value reflect.Value) error {
-	// Gobs contain values. They cannot represent nil pointers, which
-	// have no value to encode.
 	if value.Kind() == reflect.Ptr && value.IsNil() {
 		panic("gob: cannot encode nil pointer of type " + value.Type().String())
 	}
diff --git a/libgo/go/encoding/gob/encoder_test.go b/libgo/go/encoding/gob/encoder_test.go
index 570d79696bb..22090a18a6f 100644
--- a/libgo/go/encoding/gob/encoder_test.go
+++ b/libgo/go/encoding/gob/encoder_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"encoding/hex"
 	"fmt"
+	"io/ioutil"
 	"reflect"
 	"strings"
 	"testing"
@@ -280,7 +281,7 @@ func TestValueError(t *testing.T) {
 	}
 	t4p := &Type4{3}
 	var t4 Type4 // note: not a pointer.
-	if err := encAndDec(t4p, t4); err == nil || strings.Index(err.Error(), "pointer") < 0 {
+	if err := encAndDec(t4p, t4); err == nil || !strings.Contains(err.Error(), "pointer") {
 		t.Error("expected error about pointer; got", err)
 	}
 }
@@ -388,7 +389,7 @@ func TestSingletons(t *testing.T) {
 			t.Errorf("expected error decoding %v: %s", test.in, test.err)
 			continue
 		case err != nil && test.err != "":
-			if strings.Index(err.Error(), test.err) < 0 {
+			if !strings.Contains(err.Error(), test.err) {
 				t.Errorf("wrong error decoding %v: wanted %s, got %v", test.in, test.err, err)
 			}
 			continue
@@ -414,7 +415,7 @@ func TestStructNonStruct(t *testing.T) {
 	var ns NonStruct
 	if err := encAndDec(s, &ns); err == nil {
 		t.Error("should get error for struct/non-struct")
-	} else if strings.Index(err.Error(), "type") < 0 {
+	} else if !strings.Contains(err.Error(), "type") {
 		t.Error("for struct/non-struct expected type error; got", err)
 	}
 	// Now try the other way
@@ -424,7 +425,7 @@ func TestStructNonStruct(t *testing.T) {
 	}
 	if err := encAndDec(ns, &s); err == nil {
 		t.Error("should get error for non-struct/struct")
-	} else if strings.Index(err.Error(), "type") < 0 {
+	} else if !strings.Contains(err.Error(), "type") {
 		t.Error("for non-struct/struct expected type error; got", err)
 	}
 }
@@ -439,8 +440,8 @@ func (this *interfaceIndirectTestT) F() bool {
 	return true
 }
 
-// A version of a bug reported on golang-nuts.  Also tests top-level
-// slice of interfaces.  The issue was registering *T caused T to be
+// A version of a bug reported on golang-nuts. Also tests top-level
+// slice of interfaces. The issue was registering *T caused T to be
 // stored as the concrete type.
 func TestInterfaceIndirect(t *testing.T) {
 	Register(&interfaceIndirectTestT{})
@@ -463,7 +464,7 @@ func TestInterfaceIndirect(t *testing.T) {
 
 // Also, when the ignored object contains an interface value, it may define
 // types. Make sure that skipping the value still defines the types by using
-// the encoder/decoder pair to send a value afterwards.  If an interface
+// the encoder/decoder pair to send a value afterwards. If an interface
 // is sent, its type in the test is always NewType0, so this checks that the
 // encoder and decoder don't skew with respect to type definitions.
 
@@ -603,10 +604,6 @@ type Bug1Elem struct {
 
 type Bug1StructMap map[string]Bug1Elem
 
-func bug1EncDec(in Bug1StructMap, out *Bug1StructMap) error {
-	return nil
-}
-
 func TestMapBug1(t *testing.T) {
 	in := make(Bug1StructMap)
 	in["val1"] = Bug1Elem{"elem1", 1}
@@ -835,30 +832,81 @@ func TestPtrToMapOfMap(t *testing.T) {
 
 // A top-level nil pointer generates a panic with a helpful string-valued message.
 func TestTopLevelNilPointer(t *testing.T) {
-	errMsg := topLevelNilPanic(t)
-	if errMsg == "" {
+	var ip *int
+	encodeErr, panicErr := encodeAndRecover(ip)
+	if encodeErr != nil {
+		t.Fatal("error in encode:", encodeErr)
+	}
+	if panicErr == nil {
 		t.Fatal("top-level nil pointer did not panic")
 	}
+	errMsg := panicErr.Error()
 	if !strings.Contains(errMsg, "nil pointer") {
 		t.Fatal("expected nil pointer error, got:", errMsg)
 	}
 }
 
-func topLevelNilPanic(t *testing.T) (panicErr string) {
+func encodeAndRecover(value interface{}) (encodeErr, panicErr error) {
 	defer func() {
 		e := recover()
-		if err, ok := e.(string); ok {
-			panicErr = err
+		if e != nil {
+			switch err := e.(type) {
+			case error:
+				panicErr = err
+			default:
+				panicErr = fmt.Errorf("%v", err)
+			}
 		}
 	}()
-	var ip *int
-	buf := new(bytes.Buffer)
-	if err := NewEncoder(buf).Encode(ip); err != nil {
-		t.Fatal("error in encode:", err)
-	}
+
+	encodeErr = NewEncoder(ioutil.Discard).Encode(value)
 	return
 }
 
+func TestNilPointerPanics(t *testing.T) {
+	var (
+		nilStringPtr      *string
+		intMap            = make(map[int]int)
+		intMapPtr         = &intMap
+		nilIntMapPtr      *map[int]int
+		zero              int
+		nilBoolChannel    chan bool
+		nilBoolChannelPtr *chan bool
+		nilStringSlice    []string
+		stringSlice       = make([]string, 1)
+		nilStringSlicePtr *[]string
+	)
+
+	testCases := []struct {
+		value     interface{}
+		mustPanic bool
+	}{
+		{nilStringPtr, true},
+		{intMap, false},
+		{intMapPtr, false},
+		{nilIntMapPtr, true},
+		{zero, false},
+		{nilStringSlice, false},
+		{stringSlice, false},
+		{nilStringSlicePtr, true},
+		{nilBoolChannel, false},
+		{nilBoolChannelPtr, true},
+	}
+
+	for _, tt := range testCases {
+		_, panicErr := encodeAndRecover(tt.value)
+		if tt.mustPanic {
+			if panicErr == nil {
+				t.Errorf("expected panic with input %#v, did not panic", tt.value)
+			}
+			continue
+		}
+		if panicErr != nil {
+			t.Fatalf("expected no panic with input %#v, got panic=%v", tt.value, panicErr)
+		}
+	}
+}
+
 func TestNilPointerInsideInterface(t *testing.T) {
 	var ip *int
 	si := struct {
@@ -913,7 +961,7 @@ func TestMutipleEncodingsOfBadType(t *testing.T) {
 // There was an error check comparing the length of the input with the
 // length of the slice being decoded. It was wrong because the next
 // thing in the input might be a type definition, which would lead to
-// an incorrect length check.  This test reproduces the corner case.
+// an incorrect length check. This test reproduces the corner case.
 
 type Z struct {
 }
diff --git a/libgo/go/encoding/gob/error.go b/libgo/go/encoding/gob/error.go
index 92cc0c615e3..8b5265c278f 100644
--- a/libgo/go/encoding/gob/error.go
+++ b/libgo/go/encoding/gob/error.go
@@ -9,7 +9,7 @@ import "fmt"
 // Errors in decoding and encoding are handled using panic and recover.
 // Panics caused by user error (that is, everything except run-time panics
 // such as "index out of bounds" errors) do not leave the file that caused
-// them, but are instead turned into plain error returns.  Encoding and
+// them, but are instead turned into plain error returns. Encoding and
 // decoding functions and methods that do not return an error either use
 // panic to report an error or are guaranteed error-free.
 
@@ -30,7 +30,7 @@ func error_(err error) {
 }
 
 // catchError is meant to be used as a deferred function to turn a panic(gobError) into a
-// plain error.  It overwrites the error return of the function that deferred its call.
+// plain error. It overwrites the error return of the function that deferred its call.
 func catchError(err *error) {
 	if e := recover(); e != nil {
 		ge, ok := e.(gobError)
diff --git a/libgo/go/encoding/gob/gobencdec_test.go b/libgo/go/encoding/gob/gobencdec_test.go
index eb76b481d19..ecc91eef1f8 100644
--- a/libgo/go/encoding/gob/gobencdec_test.go
+++ b/libgo/go/encoding/gob/gobencdec_test.go
@@ -376,7 +376,7 @@ func TestGobEncoderIndirectArrayField(t *testing.T) {
 }
 
 // As long as the fields have the same name and implement the
-// interface, we can cross-connect them.  Not sure it's useful
+// interface, we can cross-connect them. Not sure it's useful
 // and may even be bad but it works and it's hard to prevent
 // without exposing the contents of the object, which would
 // defeat the purpose.
@@ -434,7 +434,7 @@ func TestGobEncoderValueEncoder(t *testing.T) {
 }
 
 // Test that we can use a value then a pointer type of a GobEncoder
-// in the same encoded value.  Bug 4647.
+// in the same encoded value. Bug 4647.
 func TestGobEncoderValueThenPointer(t *testing.T) {
 	v := ValueGobber("forty-two")
 	w := ValueGobber("six-by-nine")
@@ -548,7 +548,7 @@ func TestGobEncoderFieldTypeError(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected decode error for mismatched fields (encoder to non-decoder)")
 	}
-	if strings.Index(err.Error(), "type") < 0 {
+	if !strings.Contains(err.Error(), "type") {
 		t.Fatal("expected type error; got", err)
 	}
 	// Non-encoder to GobDecoder: error
@@ -562,7 +562,7 @@ func TestGobEncoderFieldTypeError(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected decode error for mismatched fields (non-encoder to decoder)")
 	}
-	if strings.Index(err.Error(), "type") < 0 {
+	if !strings.Contains(err.Error(), "type") {
 		t.Fatal("expected type error; got", err)
 	}
 }
diff --git a/libgo/go/encoding/gob/type.go b/libgo/go/encoding/gob/type.go
index cf5cec0703b..c27f7e9707e 100644
--- a/libgo/go/encoding/gob/type.go
+++ b/libgo/go/encoding/gob/type.go
@@ -17,7 +17,7 @@ import (
 )
 
 // userTypeInfo stores the information associated with a type the user has handed
-// to the package.  It's computed once and stored in a map keyed by reflection
+// to the package. It's computed once and stored in a map keyed by reflection
 // type.
 type userTypeInfo struct {
 	user        reflect.Type // the type the user handed us
@@ -44,7 +44,7 @@ var (
 )
 
 // validType returns, and saves, the information associated with user-provided type rt.
-// If the user type is not valid, err will be non-nil.  To be used when the error handler
+// If the user type is not valid, err will be non-nil. To be used when the error handler
 // is not set up.
 func validUserType(rt reflect.Type) (ut *userTypeInfo, err error) {
 	userTypeLock.RLock()
@@ -64,7 +64,7 @@ func validUserType(rt reflect.Type) (ut *userTypeInfo, err error) {
 	ut.base = rt
 	ut.user = rt
 	// A type that is just a cycle of pointers (such as type T *T) cannot
-	// be represented in gobs, which need some concrete data.  We use a
+	// be represented in gobs, which need some concrete data. We use a
 	// cycle detection algorithm from Knuth, Vol 2, Section 3.1, Ex 6,
 	// pp 539-540.  As we step through indirections, run another type at
 	// half speed. If they meet up, there's a cycle.
@@ -493,7 +493,7 @@ func newTypeObject(name string, ut *userTypeInfo, rt reflect.Type) (gobType, err
 		// For arrays, maps, and slices, we set the type id after the elements
 		// are constructed. This is to retain the order of type id allocation after
 		// a fix made to handle recursive types, which changed the order in
-		// which types are built.  Delaying the setting in this way preserves
+		// which types are built. Delaying the setting in this way preserves
 		// type ids while allowing recursive types to be described. Structs,
 		// done below, were already handling recursion correctly so they
 		// assign the top-level id before those of the field.
@@ -597,7 +597,7 @@ func getBaseType(name string, rt reflect.Type) (gobType, error) {
 
 // getType returns the Gob type describing the given reflect.Type.
 // Should be called only when handling GobEncoders/Decoders,
-// which may be pointers.  All other types are handled through the
+// which may be pointers. All other types are handled through the
 // base type, never a pointer.
 // typeLock must be held.
 func getType(name string, ut *userTypeInfo, rt reflect.Type) (gobType, error) {
@@ -642,7 +642,7 @@ func bootstrapType(name string, e interface{}, expect typeId) typeId {
 // For bootstrapping purposes, we assume that the recipient knows how
 // to decode a wireType; it is exactly the wireType struct here, interpreted
 // using the gob rules for sending a structure, except that we assume the
-// ids for wireType and structType etc. are known.  The relevant pieces
+// ids for wireType and structType etc. are known. The relevant pieces
 // are built in encode.go's init() function.
 // To maintain binary compatibility, if you extend this type, always put
 // the new fields last.
@@ -789,7 +789,7 @@ func mustGetTypeInfo(rt reflect.Type) *typeInfo {
 //
 // Note: Since gobs can be stored permanently, it is good design
 // to guarantee the encoding used by a GobEncoder is stable as the
-// software evolves.  For instance, it might make sense for GobEncode
+// software evolves. For instance, it might make sense for GobEncode
 // to include a version number in the encoding.
 type GobEncoder interface {
 	// GobEncode returns a byte slice representing the encoding of the
@@ -838,8 +838,8 @@ func RegisterName(name string, value interface{}) {
 }
 
 // Register records a type, identified by a value for that type, under its
-// internal type name.  That name will identify the concrete type of a value
-// sent or received as an interface variable.  Only types that will be
+// internal type name. That name will identify the concrete type of a value
+// sent or received as an interface variable. Only types that will be
 // transferred as implementations of interface values need to be registered.
 // Expecting to be used only during initialization, it panics if the mapping
 // between types and names is not a bijection.
diff --git a/libgo/go/encoding/hex/hex.go b/libgo/go/encoding/hex/hex.go
index d1fc7024a97..73a25034be1 100644
--- a/libgo/go/encoding/hex/hex.go
+++ b/libgo/go/encoding/hex/hex.go
@@ -18,7 +18,7 @@ const hextable = "0123456789abcdef"
 func EncodedLen(n int) int { return n * 2 }
 
 // Encode encodes src into EncodedLen(len(src))
-// bytes of dst.  As a convenience, it returns the number
+// bytes of dst. As a convenience, it returns the number
 // of bytes written to dst, but this value is always EncodedLen(len(src)).
 // Encode implements hexadecimal encoding.
 func Encode(dst, src []byte) int {
@@ -105,7 +105,7 @@ func Dump(data []byte) string {
 	dumper := Dumper(&buf)
 	dumper.Write(data)
 	dumper.Close()
-	return string(buf.Bytes())
+	return buf.String()
 }
 
 // Dumper returns a WriteCloser that writes a hex dump of all written data to
diff --git a/libgo/go/encoding/json/bench_test.go b/libgo/go/encoding/json/bench_test.go
index ed89d1156ed..cd7380b1efb 100644
--- a/libgo/go/encoding/json/bench_test.go
+++ b/libgo/go/encoding/json/bench_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -158,7 +158,7 @@ func BenchmarkCodeUnmarshal(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		var r codeResponse
 		if err := Unmarshal(codeJSON, &r); err != nil {
-			b.Fatal("Unmmarshal:", err)
+			b.Fatal("Unmarshal:", err)
 		}
 	}
 	b.SetBytes(int64(len(codeJSON)))
@@ -173,7 +173,7 @@ func BenchmarkCodeUnmarshalReuse(b *testing.B) {
 	var r codeResponse
 	for i := 0; i < b.N; i++ {
 		if err := Unmarshal(codeJSON, &r); err != nil {
-			b.Fatal("Unmmarshal:", err)
+			b.Fatal("Unmarshal:", err)
 		}
 	}
 }
diff --git a/libgo/go/encoding/json/decode.go b/libgo/go/encoding/json/decode.go
index 539d952ad68..2eda875bfde 100644
--- a/libgo/go/encoding/json/decode.go
+++ b/libgo/go/encoding/json/decode.go
@@ -29,9 +29,9 @@ import (
 // with the following additional rules:
 //
 // To unmarshal JSON into a pointer, Unmarshal first handles the case of
-// the JSON being the JSON literal null.  In that case, Unmarshal sets
-// the pointer to nil.  Otherwise, Unmarshal unmarshals the JSON into
-// the value pointed at by the pointer.  If the pointer is nil, Unmarshal
+// the JSON being the JSON literal null. In that case, Unmarshal sets
+// the pointer to nil. Otherwise, Unmarshal unmarshals the JSON into
+// the value pointed at by the pointer. If the pointer is nil, Unmarshal
 // allocates a new value for it to point to.
 //
 // To unmarshal JSON into a struct, Unmarshal matches incoming object
@@ -61,10 +61,11 @@ import (
 // If the JSON array is smaller than the Go array,
 // the additional Go array elements are set to zero values.
 //
-// To unmarshal a JSON object into a string-keyed map, Unmarshal first
-// establishes a map to use, If the map is nil, Unmarshal allocates a new map.
-// Otherwise Unmarshal reuses the existing map, keeping existing entries.
-// Unmarshal then stores key-value pairs from the JSON object into the map.
+// To unmarshal a JSON object into a map, Unmarshal first establishes a map to
+// use. If the map is nil, Unmarshal allocates a new map. Otherwise Unmarshal
+// reuses the existing map, keeping existing entries. Unmarshal then stores key-
+// value pairs from the JSON object into the map. The map's key type must
+// either be a string, an integer, or implement encoding.TextUnmarshaler.
 //
 // If a JSON value is not appropriate for a given target type,
 // or if a JSON number overflows the target type, Unmarshal
@@ -96,7 +97,7 @@ func Unmarshal(data []byte, v interface{}) error {
 	return d.unmarshal(v)
 }
 
-// Unmarshaler is the interface implemented by objects
+// Unmarshaler is the interface implemented by types
 // that can unmarshal a JSON description of themselves.
 // The input can be assumed to be a valid encoding of
 // a JSON value. UnmarshalJSON must copy the JSON data
@@ -534,7 +535,7 @@ func (d *decodeState) array(v reflect.Value) {
 
 	if i < v.Len() {
 		if v.Kind() == reflect.Array {
-			// Array.  Zero the rest.
+			// Array. Zero the rest.
 			z := reflect.Zero(v.Type().Elem())
 			for ; i < v.Len(); i++ {
 				v.Index(i).Set(z)
@@ -549,6 +550,7 @@ func (d *decodeState) array(v reflect.Value) {
 }
 
 var nullLiteral = []byte("null")
+var textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
 
 // object consumes an object from d.data[d.off-1:], decoding into the value v.
 // the first byte ('{') of the object has been read already.
@@ -577,16 +579,26 @@ func (d *decodeState) object(v reflect.Value) {
 		return
 	}
 
-	// Check type of target: struct or map[string]T
+	// Check type of target:
+	//   struct or
+	//   map[T1]T2 where T1 is string, an integer type,
+	//             or an encoding.TextUnmarshaler
 	switch v.Kind() {
 	case reflect.Map:
-		// map must have string kind
+		// Map key must either have string kind, have an integer kind,
+		// or be an encoding.TextUnmarshaler.
 		t := v.Type()
-		if t.Key().Kind() != reflect.String {
-			d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
-			d.off--
-			d.next() // skip over { } in input
-			return
+		switch t.Key().Kind() {
+		case reflect.String,
+			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		default:
+			if !reflect.PtrTo(t.Key()).Implements(textUnmarshalerType) {
+				d.saveError(&UnmarshalTypeError{"object", v.Type(), int64(d.off)})
+				d.off--
+				d.next() // skip over { } in input
+				return
+			}
 		}
 		if v.IsNil() {
 			v.Set(reflect.MakeMap(t))
@@ -687,7 +699,37 @@ func (d *decodeState) object(v reflect.Value) {
 		// Write value back to map;
 		// if using struct, subv points into struct already.
 		if v.Kind() == reflect.Map {
-			kv := reflect.ValueOf(key).Convert(v.Type().Key())
+			kt := v.Type().Key()
+			var kv reflect.Value
+			switch {
+			case kt.Kind() == reflect.String:
+				kv = reflect.ValueOf(key).Convert(kt)
+			case reflect.PtrTo(kt).Implements(textUnmarshalerType):
+				kv = reflect.New(v.Type().Key())
+				d.literalStore(item, kv, true)
+				kv = kv.Elem()
+			default:
+				switch kt.Kind() {
+				case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+					s := string(key)
+					n, err := strconv.ParseInt(s, 10, 64)
+					if err != nil || reflect.Zero(kt).OverflowInt(n) {
+						d.saveError(&UnmarshalTypeError{"number " + s, kt, int64(start + 1)})
+						return
+					}
+					kv = reflect.ValueOf(n).Convert(kt)
+				case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+					s := string(key)
+					n, err := strconv.ParseUint(s, 10, 64)
+					if err != nil || reflect.Zero(kt).OverflowUint(n) {
+						d.saveError(&UnmarshalTypeError{"number " + s, kt, int64(start + 1)})
+						return
+					}
+					kv = reflect.ValueOf(n).Convert(kt)
+				default:
+					panic("json: Unexpected key type") // should never occur
+				}
+			}
 			v.SetMapIndex(kv, subv)
 		}
 
@@ -902,7 +944,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 }
 
 // The xxxInterface routines build up a value to be stored
-// in an empty interface.  They are not strictly necessary,
+// in an empty interface. They are not strictly necessary,
 // but they avoid the weight of reflection in this common case.
 
 // valueInterface is like value but returns interface{}
diff --git a/libgo/go/encoding/json/decode_test.go b/libgo/go/encoding/json/decode_test.go
index 9546ae459cd..255ff5c66a7 100644
--- a/libgo/go/encoding/json/decode_test.go
+++ b/libgo/go/encoding/json/decode_test.go
@@ -7,10 +7,13 @@ package json
 import (
 	"bytes"
 	"encoding"
+	"errors"
 	"fmt"
 	"image"
+	"math"
 	"net"
 	"reflect"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -52,6 +55,8 @@ type tx struct {
 	x int
 }
 
+type u8 uint8
+
 // A type that can unmarshal itself.
 
 type unmarshaler struct {
@@ -68,16 +73,20 @@ type ustruct struct {
 }
 
 type unmarshalerText struct {
-	T bool
+	A, B string
 }
 
 // needed for re-marshaling tests
-func (u *unmarshalerText) MarshalText() ([]byte, error) {
-	return []byte(""), nil
+func (u unmarshalerText) MarshalText() ([]byte, error) {
+	return []byte(u.A + ":" + u.B), nil
 }
 
 func (u *unmarshalerText) UnmarshalText(b []byte) error {
-	*u = unmarshalerText{true} // All we need to see that UnmarshalText is called.
+	pos := bytes.Index(b, []byte(":"))
+	if pos == -1 {
+		return errors.New("missing separator")
+	}
+	u.A, u.B = string(b[:pos]), string(b[pos+1:])
 	return nil
 }
 
@@ -87,6 +96,29 @@ type ustructText struct {
 	M unmarshalerText
 }
 
+// u8marshal is an integer type that can marshal/unmarshal itself.
+type u8marshal uint8
+
+func (u8 u8marshal) MarshalText() ([]byte, error) {
+	return []byte(fmt.Sprintf("u%d", u8)), nil
+}
+
+var errMissingU8Prefix = errors.New("missing 'u' prefix")
+
+func (u8 *u8marshal) UnmarshalText(b []byte) error {
+	if !bytes.HasPrefix(b, []byte{'u'}) {
+		return errMissingU8Prefix
+	}
+	n, err := strconv.Atoi(string(b[1:]))
+	if err != nil {
+		return err
+	}
+	*u8 = u8marshal(n)
+	return nil
+}
+
+var _ encoding.TextUnmarshaler = (*u8marshal)(nil)
+
 var (
 	um0, um1 unmarshaler // target2 of unmarshaling
 	ump      = &um1
@@ -95,12 +127,16 @@ var (
 	umslicep = new([]unmarshaler)
 	umstruct = ustruct{unmarshaler{true}}
 
-	um0T, um1T unmarshalerText // target2 of unmarshaling
-	umpT       = &um1T
-	umtrueT    = unmarshalerText{true}
-	umsliceT   = []unmarshalerText{{true}}
-	umslicepT  = new([]unmarshalerText)
-	umstructT  = ustructText{unmarshalerText{true}}
+	um0T, um1T   unmarshalerText // target2 of unmarshaling
+	umpType      = &um1T
+	umtrueXY     = unmarshalerText{"x", "y"}
+	umsliceXY    = []unmarshalerText{{"x", "y"}}
+	umslicepType = new([]unmarshalerText)
+	umstructType = new(ustructText)
+	umstructXY   = ustructText{unmarshalerText{"x", "y"}}
+
+	ummapType = map[unmarshalerText]bool{}
+	ummapXY   = map[unmarshalerText]bool{unmarshalerText{"x", "y"}: true}
 )
 
 // Test data structures for anonymous fields.
@@ -202,14 +238,6 @@ type S13 struct {
 	S8
 }
 
-type unmarshalTest struct {
-	in        string
-	ptr       interface{}
-	out       interface{}
-	err       error
-	useNumber bool
-}
-
 type Ambig struct {
 	// Given "hello", the first match should win.
 	First  int `json:"HELLO"`
@@ -225,6 +253,127 @@ type XYZ struct {
 func sliceAddr(x []int) *[]int                 { return &x }
 func mapAddr(x map[string]int) *map[string]int { return &x }
 
+type byteWithMarshalJSON byte
+
+func (b byteWithMarshalJSON) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf(`"Z%.2x"`, byte(b))), nil
+}
+
+func (b *byteWithMarshalJSON) UnmarshalJSON(data []byte) error {
+	if len(data) != 5 || data[0] != '"' || data[1] != 'Z' || data[4] != '"' {
+		return fmt.Errorf("bad quoted string")
+	}
+	i, err := strconv.ParseInt(string(data[2:4]), 16, 8)
+	if err != nil {
+		return fmt.Errorf("bad hex")
+	}
+	*b = byteWithMarshalJSON(i)
+	return nil
+}
+
+type byteWithPtrMarshalJSON byte
+
+func (b *byteWithPtrMarshalJSON) MarshalJSON() ([]byte, error) {
+	return byteWithMarshalJSON(*b).MarshalJSON()
+}
+
+func (b *byteWithPtrMarshalJSON) UnmarshalJSON(data []byte) error {
+	return (*byteWithMarshalJSON)(b).UnmarshalJSON(data)
+}
+
+type byteWithMarshalText byte
+
+func (b byteWithMarshalText) MarshalText() ([]byte, error) {
+	return []byte(fmt.Sprintf(`Z%.2x`, byte(b))), nil
+}
+
+func (b *byteWithMarshalText) UnmarshalText(data []byte) error {
+	if len(data) != 3 || data[0] != 'Z' {
+		return fmt.Errorf("bad quoted string")
+	}
+	i, err := strconv.ParseInt(string(data[1:3]), 16, 8)
+	if err != nil {
+		return fmt.Errorf("bad hex")
+	}
+	*b = byteWithMarshalText(i)
+	return nil
+}
+
+type byteWithPtrMarshalText byte
+
+func (b *byteWithPtrMarshalText) MarshalText() ([]byte, error) {
+	return byteWithMarshalText(*b).MarshalText()
+}
+
+func (b *byteWithPtrMarshalText) UnmarshalText(data []byte) error {
+	return (*byteWithMarshalText)(b).UnmarshalText(data)
+}
+
+type intWithMarshalJSON int
+
+func (b intWithMarshalJSON) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf(`"Z%.2x"`, int(b))), nil
+}
+
+func (b *intWithMarshalJSON) UnmarshalJSON(data []byte) error {
+	if len(data) != 5 || data[0] != '"' || data[1] != 'Z' || data[4] != '"' {
+		return fmt.Errorf("bad quoted string")
+	}
+	i, err := strconv.ParseInt(string(data[2:4]), 16, 8)
+	if err != nil {
+		return fmt.Errorf("bad hex")
+	}
+	*b = intWithMarshalJSON(i)
+	return nil
+}
+
+type intWithPtrMarshalJSON int
+
+func (b *intWithPtrMarshalJSON) MarshalJSON() ([]byte, error) {
+	return intWithMarshalJSON(*b).MarshalJSON()
+}
+
+func (b *intWithPtrMarshalJSON) UnmarshalJSON(data []byte) error {
+	return (*intWithMarshalJSON)(b).UnmarshalJSON(data)
+}
+
+type intWithMarshalText int
+
+func (b intWithMarshalText) MarshalText() ([]byte, error) {
+	return []byte(fmt.Sprintf(`Z%.2x`, int(b))), nil
+}
+
+func (b *intWithMarshalText) UnmarshalText(data []byte) error {
+	if len(data) != 3 || data[0] != 'Z' {
+		return fmt.Errorf("bad quoted string")
+	}
+	i, err := strconv.ParseInt(string(data[1:3]), 16, 8)
+	if err != nil {
+		return fmt.Errorf("bad hex")
+	}
+	*b = intWithMarshalText(i)
+	return nil
+}
+
+type intWithPtrMarshalText int
+
+func (b *intWithPtrMarshalText) MarshalText() ([]byte, error) {
+	return intWithMarshalText(*b).MarshalText()
+}
+
+func (b *intWithPtrMarshalText) UnmarshalText(data []byte) error {
+	return (*intWithMarshalText)(b).UnmarshalText(data)
+}
+
+type unmarshalTest struct {
+	in        string
+	ptr       interface{}
+	out       interface{}
+	err       error
+	useNumber bool
+	golden    bool
+}
+
 var unmarshalTests = []unmarshalTest{
 	// basic types
 	{in: `true`, ptr: new(bool), out: true},
@@ -302,14 +451,81 @@ var unmarshalTests = []unmarshalTest{
 	{in: `{"T":false}`, ptr: &ump, out: &umtrue},
 	{in: `[{"T":false}]`, ptr: &umslice, out: umslice},
 	{in: `[{"T":false}]`, ptr: &umslicep, out: &umslice},
-	{in: `{"M":{"T":false}}`, ptr: &umstruct, out: umstruct},
+	{in: `{"M":{"T":"x:y"}}`, ptr: &umstruct, out: umstruct},
 
 	// UnmarshalText interface test
-	{in: `"X"`, ptr: &um0T, out: umtrueT}, // use "false" so test will fail if custom unmarshaler is not called
-	{in: `"X"`, ptr: &umpT, out: &umtrueT},
-	{in: `["X"]`, ptr: &umsliceT, out: umsliceT},
-	{in: `["X"]`, ptr: &umslicepT, out: &umsliceT},
-	{in: `{"M":"X"}`, ptr: &umstructT, out: umstructT},
+	{in: `"x:y"`, ptr: &um0T, out: umtrueXY},
+	{in: `"x:y"`, ptr: &umpType, out: &umtrueXY},
+	{in: `["x:y"]`, ptr: &umsliceXY, out: umsliceXY},
+	{in: `["x:y"]`, ptr: &umslicepType, out: &umsliceXY},
+	{in: `{"M":"x:y"}`, ptr: umstructType, out: umstructXY},
+
+	// integer-keyed map test
+	{
+		in:  `{"-1":"a","0":"b","1":"c"}`,
+		ptr: new(map[int]string),
+		out: map[int]string{-1: "a", 0: "b", 1: "c"},
+	},
+	{
+		in:  `{"0":"a","10":"c","9":"b"}`,
+		ptr: new(map[u8]string),
+		out: map[u8]string{0: "a", 9: "b", 10: "c"},
+	},
+	{
+		in:  `{"-9223372036854775808":"min","9223372036854775807":"max"}`,
+		ptr: new(map[int64]string),
+		out: map[int64]string{math.MinInt64: "min", math.MaxInt64: "max"},
+	},
+	{
+		in:  `{"18446744073709551615":"max"}`,
+		ptr: new(map[uint64]string),
+		out: map[uint64]string{math.MaxUint64: "max"},
+	},
+	{
+		in:  `{"0":false,"10":true}`,
+		ptr: new(map[uintptr]bool),
+		out: map[uintptr]bool{0: false, 10: true},
+	},
+
+	// Check that MarshalText and UnmarshalText take precedence
+	// over default integer handling in map keys.
+	{
+		in:  `{"u2":4}`,
+		ptr: new(map[u8marshal]int),
+		out: map[u8marshal]int{2: 4},
+	},
+	{
+		in:  `{"2":4}`,
+		ptr: new(map[u8marshal]int),
+		err: errMissingU8Prefix,
+	},
+
+	// integer-keyed map errors
+	{
+		in:  `{"abc":"abc"}`,
+		ptr: new(map[int]string),
+		err: &UnmarshalTypeError{"number abc", reflect.TypeOf(0), 2},
+	},
+	{
+		in:  `{"256":"abc"}`,
+		ptr: new(map[uint8]string),
+		err: &UnmarshalTypeError{"number 256", reflect.TypeOf(uint8(0)), 2},
+	},
+	{
+		in:  `{"128":"abc"}`,
+		ptr: new(map[int8]string),
+		err: &UnmarshalTypeError{"number 128", reflect.TypeOf(int8(0)), 2},
+	},
+	{
+		in:  `{"-1":"abc"}`,
+		ptr: new(map[uint8]string),
+		err: &UnmarshalTypeError{"number -1", reflect.TypeOf(uint8(0)), 2},
+	},
+
+	// Map keys can be encoding.TextUnmarshalers.
+	{in: `{"x:y":true}`, ptr: &ummapType, out: ummapXY},
+	// If multiple values for the same key exists, only the most recent value is used.
+	{in: `{"x:y":false,"x:y":true}`, ptr: &ummapType, out: ummapXY},
 
 	// Overwriting of data.
 	// This is different from package xml, but it's what we've always done.
@@ -426,11 +642,101 @@ var unmarshalTests = []unmarshalTest{
 		out: "hello\ufffd\ufffd\ufffd\ufffd\ufffd\ufffdworld",
 	},
 
-	// issue 8305
+	// Used to be issue 8305, but time.Time implements encoding.TextUnmarshaler so this works now.
 	{
 		in:  `{"2009-11-10T23:00:00Z": "hello world"}`,
 		ptr: &map[time.Time]string{},
-		err: &UnmarshalTypeError{"object", reflect.TypeOf(map[time.Time]string{}), 1},
+		out: map[time.Time]string{time.Date(2009, 11, 10, 23, 0, 0, 0, time.UTC): "hello world"},
+	},
+
+	// issue 8305
+	{
+		in:  `{"2009-11-10T23:00:00Z": "hello world"}`,
+		ptr: &map[Point]string{},
+		err: &UnmarshalTypeError{"object", reflect.TypeOf(map[Point]string{}), 1},
+	},
+	{
+		in:  `{"asdf": "hello world"}`,
+		ptr: &map[unmarshaler]string{},
+		err: &UnmarshalTypeError{"object", reflect.TypeOf(map[unmarshaler]string{}), 1},
+	},
+
+	// related to issue 13783.
+	// Go 1.7 changed marshaling a slice of typed byte to use the methods on the byte type,
+	// similar to marshaling a slice of typed int.
+	// These tests check that, assuming the byte type also has valid decoding methods,
+	// either the old base64 string encoding or the new per-element encoding can be
+	// successfully unmarshaled. The custom unmarshalers were accessible in earlier
+	// versions of Go, even though the custom marshaler was not.
+	{
+		in:  `"AQID"`,
+		ptr: new([]byteWithMarshalJSON),
+		out: []byteWithMarshalJSON{1, 2, 3},
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]byteWithMarshalJSON),
+		out:    []byteWithMarshalJSON{1, 2, 3},
+		golden: true,
+	},
+	{
+		in:  `"AQID"`,
+		ptr: new([]byteWithMarshalText),
+		out: []byteWithMarshalText{1, 2, 3},
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]byteWithMarshalText),
+		out:    []byteWithMarshalText{1, 2, 3},
+		golden: true,
+	},
+	{
+		in:  `"AQID"`,
+		ptr: new([]byteWithPtrMarshalJSON),
+		out: []byteWithPtrMarshalJSON{1, 2, 3},
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]byteWithPtrMarshalJSON),
+		out:    []byteWithPtrMarshalJSON{1, 2, 3},
+		golden: true,
+	},
+	{
+		in:  `"AQID"`,
+		ptr: new([]byteWithPtrMarshalText),
+		out: []byteWithPtrMarshalText{1, 2, 3},
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]byteWithPtrMarshalText),
+		out:    []byteWithPtrMarshalText{1, 2, 3},
+		golden: true,
+	},
+
+	// ints work with the marshaler but not the base64 []byte case
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]intWithMarshalJSON),
+		out:    []intWithMarshalJSON{1, 2, 3},
+		golden: true,
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]intWithMarshalText),
+		out:    []intWithMarshalText{1, 2, 3},
+		golden: true,
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]intWithPtrMarshalJSON),
+		out:    []intWithPtrMarshalJSON{1, 2, 3},
+		golden: true,
+	},
+	{
+		in:     `["Z01","Z02","Z03"]`,
+		ptr:    new([]intWithPtrMarshalText),
+		out:    []intWithPtrMarshalText{1, 2, 3},
+		golden: true,
 	},
 }
 
@@ -565,13 +871,16 @@ func TestUnmarshal(t *testing.T) {
 			continue
 		}
 
-		// Check round trip.
+		// Check round trip also decodes correctly.
 		if tt.err == nil {
 			enc, err := Marshal(v.Interface())
 			if err != nil {
 				t.Errorf("#%d: error re-marshaling: %v", i, err)
 				continue
 			}
+			if tt.golden && !bytes.Equal(enc, in) {
+				t.Errorf("#%d: remarshal mismatch:\nhave: %s\nwant: %s", i, enc, in)
+			}
 			vv := reflect.New(reflect.TypeOf(tt.ptr).Elem())
 			dec = NewDecoder(bytes.NewReader(enc))
 			if tt.useNumber {
@@ -1270,7 +1579,7 @@ func TestSliceOfCustomByte(t *testing.T) {
 		t.Fatal(err)
 	}
 	if !reflect.DeepEqual(a, b) {
-		t.Fatal("expected %v == %v", a, b)
+		t.Fatalf("expected %v == %v", a, b)
 	}
 }
 
diff --git a/libgo/go/encoding/json/encode.go b/libgo/go/encoding/json/encode.go
index 69ac7e03c8d..6bb6de8f079 100644
--- a/libgo/go/encoding/json/encode.go
+++ b/libgo/go/encoding/json/encode.go
@@ -1,9 +1,9 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package json implements encoding and decoding of JSON objects as defined in
-// RFC 4627. The mapping between JSON objects and Go values is described
+// Package json implements encoding and decoding of JSON as defined in
+// RFC 4627. The mapping between JSON and Go values is described
 // in the documentation for the Marshal and Unmarshal functions.
 //
 // See "JSON and Go" for an introduction to this package:
@@ -22,6 +22,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"unicode"
 	"unicode/utf8"
 )
@@ -49,10 +50,11 @@ import (
 // The angle brackets "<" and ">" are escaped to "\u003c" and "\u003e"
 // to keep some browsers from misinterpreting JSON output as HTML.
 // Ampersand "&" is also escaped to "\u0026" for the same reason.
+// This escaping can be disabled using an Encoder with DisableHTMLEscaping.
 //
 // Array and slice values encode as JSON arrays, except that
 // []byte encodes as a base64-encoded string, and a nil slice
-// encodes as the null JSON object.
+// encodes as the null JSON value.
 //
 // Struct values encode as JSON objects. Each exported struct field
 // becomes a member of the object unless
@@ -89,8 +91,8 @@ import (
 //    Int64String int64 `json:",string"`
 //
 // The key name will be used if it's a non-empty string consisting of
-// only Unicode letters, digits, dollar signs, percent signs, hyphens,
-// underscores and slashes.
+// only Unicode letters, digits, and ASCII punctuation except quotation
+// marks, backslash, and comma.
 //
 // Anonymous struct fields are usually marshaled as if their inner exported fields
 // were fields in the outer struct, subject to the usual Go visibility rules amended
@@ -116,27 +118,31 @@ import (
 // an anonymous struct field in both current and earlier versions, give the field
 // a JSON tag of "-".
 //
-// Map values encode as JSON objects.
-// The map's key type must be string; the map keys are used as JSON object
-// keys, subject to the UTF-8 coercion described for string values above.
+// Map values encode as JSON objects. The map's key type must either be a
+// string, an integer type, or implement encoding.TextMarshaler. The map keys
+// are sorted and used as JSON object keys by applying the following rules,
+// subject to the UTF-8 coercion described for string values above:
+//   - string keys are used directly
+//   - encoding.TextMarshalers are marshaled
+//   - integer keys are converted to strings
 //
 // Pointer values encode as the value pointed to.
-// A nil pointer encodes as the null JSON object.
+// A nil pointer encodes as the null JSON value.
 //
 // Interface values encode as the value contained in the interface.
-// A nil interface value encodes as the null JSON object.
+// A nil interface value encodes as the null JSON value.
 //
 // Channel, complex, and function values cannot be encoded in JSON.
 // Attempting to encode such a value causes Marshal to return
 // an UnsupportedTypeError.
 //
 // JSON cannot represent cyclic data structures and Marshal does not
-// handle them.  Passing cyclic structures to Marshal will result in
+// handle them. Passing cyclic structures to Marshal will result in
 // an infinite recursion.
 //
 func Marshal(v interface{}) ([]byte, error) {
 	e := &encodeState{}
-	err := e.marshal(v)
+	err := e.marshal(v, encOpts{escapeHTML: true})
 	if err != nil {
 		return nil, err
 	}
@@ -192,7 +198,7 @@ func HTMLEscape(dst *bytes.Buffer, src []byte) {
 	}
 }
 
-// Marshaler is the interface implemented by objects that
+// Marshaler is the interface implemented by types that
 // can marshal themselves into valid JSON.
 type Marshaler interface {
 	MarshalJSON() ([]byte, error)
@@ -259,7 +265,7 @@ func newEncodeState() *encodeState {
 	return new(encodeState)
 }
 
-func (e *encodeState) marshal(v interface{}) (err error) {
+func (e *encodeState) marshal(v interface{}, opts encOpts) (err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			if _, ok := r.(runtime.Error); ok {
@@ -271,7 +277,7 @@ func (e *encodeState) marshal(v interface{}) (err error) {
 			err = r.(error)
 		}
 	}()
-	e.reflectValue(reflect.ValueOf(v))
+	e.reflectValue(reflect.ValueOf(v), opts)
 	return nil
 }
 
@@ -297,11 +303,18 @@ func isEmptyValue(v reflect.Value) bool {
 	return false
 }
 
-func (e *encodeState) reflectValue(v reflect.Value) {
-	valueEncoder(v)(e, v, false)
+func (e *encodeState) reflectValue(v reflect.Value, opts encOpts) {
+	valueEncoder(v)(e, v, opts)
 }
 
-type encoderFunc func(e *encodeState, v reflect.Value, quoted bool)
+type encOpts struct {
+	// quoted causes primitive fields to be encoded inside JSON strings.
+	quoted bool
+	// escapeHTML causes '<', '>', and '&' to be escaped in JSON strings.
+	escapeHTML bool
+}
+
+type encoderFunc func(e *encodeState, v reflect.Value, opts encOpts)
 
 var encoderCache struct {
 	sync.RWMutex
@@ -325,7 +338,7 @@ func typeEncoder(t reflect.Type) encoderFunc {
 
 	// To deal with recursive types, populate the map with an
 	// indirect func before we build it. This type waits on the
-	// real func (f) to be ready and then calls it.  This indirect
+	// real func (f) to be ready and then calls it. This indirect
 	// func is only used for recursive types.
 	encoderCache.Lock()
 	if encoderCache.m == nil {
@@ -333,9 +346,9 @@ func typeEncoder(t reflect.Type) encoderFunc {
 	}
 	var wg sync.WaitGroup
 	wg.Add(1)
-	encoderCache.m[t] = func(e *encodeState, v reflect.Value, quoted bool) {
+	encoderCache.m[t] = func(e *encodeState, v reflect.Value, opts encOpts) {
 		wg.Wait()
-		f(e, v, quoted)
+		f(e, v, opts)
 	}
 	encoderCache.Unlock()
 
@@ -405,11 +418,11 @@ func newTypeEncoder(t reflect.Type, allowAddr bool) encoderFunc {
 	}
 }
 
-func invalidValueEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func invalidValueEncoder(e *encodeState, v reflect.Value, _ encOpts) {
 	e.WriteString("null")
 }
 
-func marshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func marshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.Kind() == reflect.Ptr && v.IsNil() {
 		e.WriteString("null")
 		return
@@ -418,14 +431,14 @@ func marshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
 	b, err := m.MarshalJSON()
 	if err == nil {
 		// copy JSON into buffer, checking validity.
-		err = compact(&e.Buffer, b, true)
+		err = compact(&e.Buffer, b, opts.escapeHTML)
 	}
 	if err != nil {
 		e.error(&MarshalerError{v.Type(), err})
 	}
 }
 
-func addrMarshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func addrMarshalerEncoder(e *encodeState, v reflect.Value, _ encOpts) {
 	va := v.Addr()
 	if va.IsNil() {
 		e.WriteString("null")
@@ -442,7 +455,7 @@ func addrMarshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
 	}
 }
 
-func textMarshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func textMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.Kind() == reflect.Ptr && v.IsNil() {
 		e.WriteString("null")
 		return
@@ -452,10 +465,10 @@ func textMarshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
 	if err != nil {
 		e.error(&MarshalerError{v.Type(), err})
 	}
-	e.stringBytes(b)
+	e.stringBytes(b, opts.escapeHTML)
 }
 
-func addrTextMarshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func addrTextMarshalerEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	va := v.Addr()
 	if va.IsNil() {
 		e.WriteString("null")
@@ -466,11 +479,11 @@ func addrTextMarshalerEncoder(e *encodeState, v reflect.Value, quoted bool) {
 	if err != nil {
 		e.error(&MarshalerError{v.Type(), err})
 	}
-	e.stringBytes(b)
+	e.stringBytes(b, opts.escapeHTML)
 }
 
-func boolEncoder(e *encodeState, v reflect.Value, quoted bool) {
-	if quoted {
+func boolEncoder(e *encodeState, v reflect.Value, opts encOpts) {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 	if v.Bool() {
@@ -478,46 +491,46 @@ func boolEncoder(e *encodeState, v reflect.Value, quoted bool) {
 	} else {
 		e.WriteString("false")
 	}
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 }
 
-func intEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func intEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	b := strconv.AppendInt(e.scratch[:0], v.Int(), 10)
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 	e.Write(b)
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 }
 
-func uintEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func uintEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	b := strconv.AppendUint(e.scratch[:0], v.Uint(), 10)
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 	e.Write(b)
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 }
 
 type floatEncoder int // number of bits
 
-func (bits floatEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
+func (bits floatEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	f := v.Float()
 	if math.IsInf(f, 0) || math.IsNaN(f) {
 		e.error(&UnsupportedValueError{v, strconv.FormatFloat(f, 'g', -1, int(bits))})
 	}
 	b := strconv.AppendFloat(e.scratch[:0], f, 'g', -1, int(bits))
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 	e.Write(b)
-	if quoted {
+	if opts.quoted {
 		e.WriteByte('"')
 	}
 }
@@ -527,7 +540,7 @@ var (
 	float64Encoder = (floatEncoder(64)).encode
 )
 
-func stringEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func stringEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.Type() == numberType {
 		numStr := v.String()
 		// In Go1.5 the empty string encodes to "0", while this is not a valid number literal
@@ -541,26 +554,26 @@ func stringEncoder(e *encodeState, v reflect.Value, quoted bool) {
 		e.WriteString(numStr)
 		return
 	}
-	if quoted {
+	if opts.quoted {
 		sb, err := Marshal(v.String())
 		if err != nil {
 			e.error(err)
 		}
-		e.string(string(sb))
+		e.string(string(sb), opts.escapeHTML)
 	} else {
-		e.string(v.String())
+		e.string(v.String(), opts.escapeHTML)
 	}
 }
 
-func interfaceEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func interfaceEncoder(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
 	}
-	e.reflectValue(v.Elem())
+	e.reflectValue(v.Elem(), opts)
 }
 
-func unsupportedTypeEncoder(e *encodeState, v reflect.Value, quoted bool) {
+func unsupportedTypeEncoder(e *encodeState, v reflect.Value, _ encOpts) {
 	e.error(&UnsupportedTypeError{v.Type()})
 }
 
@@ -569,7 +582,7 @@ type structEncoder struct {
 	fieldEncs []encoderFunc
 }
 
-func (se *structEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
+func (se *structEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	e.WriteByte('{')
 	first := true
 	for i, f := range se.fields {
@@ -582,9 +595,10 @@ func (se *structEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
 		} else {
 			e.WriteByte(',')
 		}
-		e.string(f.name)
+		e.string(f.name, opts.escapeHTML)
 		e.WriteByte(':')
-		se.fieldEncs[i](e, fv, f.quoted)
+		opts.quoted = f.quoted
+		se.fieldEncs[i](e, fv, opts)
 	}
 	e.WriteByte('}')
 }
@@ -605,34 +619,50 @@ type mapEncoder struct {
 	elemEnc encoderFunc
 }
 
-func (me *mapEncoder) encode(e *encodeState, v reflect.Value, _ bool) {
+func (me *mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
 	}
 	e.WriteByte('{')
-	var sv stringValues = v.MapKeys()
-	sort.Sort(sv)
-	for i, k := range sv {
+
+	// Extract and sort the keys.
+	keys := v.MapKeys()
+	sv := make([]reflectWithString, len(keys))
+	for i, v := range keys {
+		sv[i].v = v
+		if err := sv[i].resolve(); err != nil {
+			e.error(&MarshalerError{v.Type(), err})
+		}
+	}
+	sort.Sort(byString(sv))
+
+	for i, kv := range sv {
 		if i > 0 {
 			e.WriteByte(',')
 		}
-		e.string(k.String())
+		e.string(kv.s, opts.escapeHTML)
 		e.WriteByte(':')
-		me.elemEnc(e, v.MapIndex(k), false)
+		me.elemEnc(e, v.MapIndex(kv.v), opts)
 	}
 	e.WriteByte('}')
 }
 
 func newMapEncoder(t reflect.Type) encoderFunc {
-	if t.Key().Kind() != reflect.String {
-		return unsupportedTypeEncoder
+	switch t.Key().Kind() {
+	case reflect.String,
+		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+	default:
+		if !t.Key().Implements(textMarshalerType) {
+			return unsupportedTypeEncoder
+		}
 	}
 	me := &mapEncoder{typeEncoder(t.Elem())}
 	return me.encode
 }
 
-func encodeByteSlice(e *encodeState, v reflect.Value, _ bool) {
+func encodeByteSlice(e *encodeState, v reflect.Value, _ encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
@@ -659,18 +689,21 @@ type sliceEncoder struct {
 	arrayEnc encoderFunc
 }
 
-func (se *sliceEncoder) encode(e *encodeState, v reflect.Value, _ bool) {
+func (se *sliceEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
 	}
-	se.arrayEnc(e, v, false)
+	se.arrayEnc(e, v, opts)
 }
 
 func newSliceEncoder(t reflect.Type) encoderFunc {
 	// Byte slices get special treatment; arrays don't.
 	if t.Elem().Kind() == reflect.Uint8 {
-		return encodeByteSlice
+		p := reflect.PtrTo(t.Elem())
+		if !p.Implements(marshalerType) && !p.Implements(textMarshalerType) {
+			return encodeByteSlice
+		}
 	}
 	enc := &sliceEncoder{newArrayEncoder(t)}
 	return enc.encode
@@ -680,14 +713,14 @@ type arrayEncoder struct {
 	elemEnc encoderFunc
 }
 
-func (ae *arrayEncoder) encode(e *encodeState, v reflect.Value, _ bool) {
+func (ae *arrayEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	e.WriteByte('[')
 	n := v.Len()
 	for i := 0; i < n; i++ {
 		if i > 0 {
 			e.WriteByte(',')
 		}
-		ae.elemEnc(e, v.Index(i), false)
+		ae.elemEnc(e, v.Index(i), opts)
 	}
 	e.WriteByte(']')
 }
@@ -701,12 +734,12 @@ type ptrEncoder struct {
 	elemEnc encoderFunc
 }
 
-func (pe *ptrEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
+func (pe *ptrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
 	}
-	pe.elemEnc(e, v.Elem(), quoted)
+	pe.elemEnc(e, v.Elem(), opts)
 }
 
 func newPtrEncoder(t reflect.Type) encoderFunc {
@@ -718,11 +751,11 @@ type condAddrEncoder struct {
 	canAddrEnc, elseEnc encoderFunc
 }
 
-func (ce *condAddrEncoder) encode(e *encodeState, v reflect.Value, quoted bool) {
+func (ce *condAddrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.CanAddr() {
-		ce.canAddrEnc(e, v, quoted)
+		ce.canAddrEnc(e, v, opts)
 	} else {
-		ce.elseEnc(e, v, quoted)
+		ce.elseEnc(e, v, opts)
 	}
 }
 
@@ -775,23 +808,50 @@ func typeByIndex(t reflect.Type, index []int) reflect.Type {
 	return t
 }
 
-// stringValues is a slice of reflect.Value holding *reflect.StringValue.
+type reflectWithString struct {
+	v reflect.Value
+	s string
+}
+
+func (w *reflectWithString) resolve() error {
+	if w.v.Kind() == reflect.String {
+		w.s = w.v.String()
+		return nil
+	}
+	if tm, ok := w.v.Interface().(encoding.TextMarshaler); ok {
+		buf, err := tm.MarshalText()
+		w.s = string(buf)
+		return err
+	}
+	switch w.v.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		w.s = strconv.FormatInt(w.v.Int(), 10)
+		return nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		w.s = strconv.FormatUint(w.v.Uint(), 10)
+		return nil
+	}
+	panic("unexpected map key type")
+}
+
+// byString is a slice of reflectWithString where the reflect.Value is either
+// a string or an encoding.TextMarshaler.
 // It implements the methods to sort by string.
-type stringValues []reflect.Value
+type byString []reflectWithString
 
-func (sv stringValues) Len() int           { return len(sv) }
-func (sv stringValues) Swap(i, j int)      { sv[i], sv[j] = sv[j], sv[i] }
-func (sv stringValues) Less(i, j int) bool { return sv.get(i) < sv.get(j) }
-func (sv stringValues) get(i int) string   { return sv[i].String() }
+func (sv byString) Len() int           { return len(sv) }
+func (sv byString) Swap(i, j int)      { sv[i], sv[j] = sv[j], sv[i] }
+func (sv byString) Less(i, j int) bool { return sv[i].s < sv[j].s }
 
 // NOTE: keep in sync with stringBytes below.
-func (e *encodeState) string(s string) int {
+func (e *encodeState) string(s string, escapeHTML bool) int {
 	len0 := e.Len()
 	e.WriteByte('"')
 	start := 0
 	for i := 0; i < len(s); {
 		if b := s[i]; b < utf8.RuneSelf {
-			if 0x20 <= b && b != '\\' && b != '"' && b != '<' && b != '>' && b != '&' {
+			if 0x20 <= b && b != '\\' && b != '"' &&
+				(!escapeHTML || b != '<' && b != '>' && b != '&') {
 				i++
 				continue
 			}
@@ -812,10 +872,11 @@ func (e *encodeState) string(s string) int {
 				e.WriteByte('\\')
 				e.WriteByte('t')
 			default:
-				// This encodes bytes < 0x20 except for \n and \r,
-				// as well as <, > and &. The latter are escaped because they
-				// can lead to security holes when user-controlled strings
-				// are rendered into JSON and served to some browsers.
+				// This encodes bytes < 0x20 except for \t, \n and \r.
+				// If escapeHTML is set, it also escapes <, >, and &
+				// because they can lead to security holes when
+				// user-controlled strings are rendered into JSON
+				// and served to some browsers.
 				e.WriteString(`\u00`)
 				e.WriteByte(hex[b>>4])
 				e.WriteByte(hex[b&0xF])
@@ -861,13 +922,14 @@ func (e *encodeState) string(s string) int {
 }
 
 // NOTE: keep in sync with string above.
-func (e *encodeState) stringBytes(s []byte) int {
+func (e *encodeState) stringBytes(s []byte, escapeHTML bool) int {
 	len0 := e.Len()
 	e.WriteByte('"')
 	start := 0
 	for i := 0; i < len(s); {
 		if b := s[i]; b < utf8.RuneSelf {
-			if 0x20 <= b && b != '\\' && b != '"' && b != '<' && b != '>' && b != '&' {
+			if 0x20 <= b && b != '\\' && b != '"' &&
+				(!escapeHTML || b != '<' && b != '>' && b != '&') {
 				i++
 				continue
 			}
@@ -888,10 +950,11 @@ func (e *encodeState) stringBytes(s []byte) int {
 				e.WriteByte('\\')
 				e.WriteByte('t')
 			default:
-				// This encodes bytes < 0x20 except for \n and \r,
-				// as well as <, >, and &. The latter are escaped because they
-				// can lead to security holes when user-controlled strings
-				// are rendered into JSON and served to some browsers.
+				// This encodes bytes < 0x20 except for \t, \n and \r.
+				// If escapeHTML is set, it also escapes <, >, and &
+				// because they can lead to security holes when
+				// user-controlled strings are rendered into JSON
+				// and served to some browsers.
 				e.WriteString(`\u00`)
 				e.WriteByte(hex[b>>4])
 				e.WriteByte(hex[b&0xF])
@@ -1169,15 +1232,14 @@ func dominantField(fields []field) (field, bool) {
 }
 
 var fieldCache struct {
-	sync.RWMutex
-	m map[reflect.Type][]field
+	value atomic.Value // map[reflect.Type][]field
+	mu    sync.Mutex   // used only by writers
 }
 
 // cachedTypeFields is like typeFields but uses a cache to avoid repeated work.
 func cachedTypeFields(t reflect.Type) []field {
-	fieldCache.RLock()
-	f := fieldCache.m[t]
-	fieldCache.RUnlock()
+	m, _ := fieldCache.value.Load().(map[reflect.Type][]field)
+	f := m[t]
 	if f != nil {
 		return f
 	}
@@ -1189,11 +1251,14 @@ func cachedTypeFields(t reflect.Type) []field {
 		f = []field{}
 	}
 
-	fieldCache.Lock()
-	if fieldCache.m == nil {
-		fieldCache.m = map[reflect.Type][]field{}
+	fieldCache.mu.Lock()
+	m, _ = fieldCache.value.Load().(map[reflect.Type][]field)
+	newM := make(map[reflect.Type][]field, len(m)+1)
+	for k, v := range m {
+		newM[k] = v
 	}
-	fieldCache.m[t] = f
-	fieldCache.Unlock()
+	newM[t] = f
+	fieldCache.value.Store(newM)
+	fieldCache.mu.Unlock()
 	return f
 }
diff --git a/libgo/go/encoding/json/encode_test.go b/libgo/go/encoding/json/encode_test.go
index c00491e00c0..b484022a70e 100644
--- a/libgo/go/encoding/json/encode_test.go
+++ b/libgo/go/encoding/json/encode_test.go
@@ -6,6 +6,7 @@ package json
 
 import (
 	"bytes"
+	"fmt"
 	"math"
 	"reflect"
 	"testing"
@@ -375,41 +376,45 @@ func TestDuplicatedFieldDisappears(t *testing.T) {
 
 func TestStringBytes(t *testing.T) {
 	// Test that encodeState.stringBytes and encodeState.string use the same encoding.
-	es := &encodeState{}
 	var r []rune
 	for i := '\u0000'; i <= unicode.MaxRune; i++ {
 		r = append(r, i)
 	}
 	s := string(r) + "\xff\xff\xffhello" // some invalid UTF-8 too
-	es.string(s)
 
-	esBytes := &encodeState{}
-	esBytes.stringBytes([]byte(s))
+	for _, escapeHTML := range []bool{true, false} {
+		es := &encodeState{}
+		es.string(s, escapeHTML)
 
-	enc := es.Buffer.String()
-	encBytes := esBytes.Buffer.String()
-	if enc != encBytes {
-		i := 0
-		for i < len(enc) && i < len(encBytes) && enc[i] == encBytes[i] {
-			i++
-		}
-		enc = enc[i:]
-		encBytes = encBytes[i:]
-		i = 0
-		for i < len(enc) && i < len(encBytes) && enc[len(enc)-i-1] == encBytes[len(encBytes)-i-1] {
-			i++
-		}
-		enc = enc[:len(enc)-i]
-		encBytes = encBytes[:len(encBytes)-i]
+		esBytes := &encodeState{}
+		esBytes.stringBytes([]byte(s), escapeHTML)
 
-		if len(enc) > 20 {
-			enc = enc[:20] + "..."
-		}
-		if len(encBytes) > 20 {
-			encBytes = encBytes[:20] + "..."
-		}
+		enc := es.Buffer.String()
+		encBytes := esBytes.Buffer.String()
+		if enc != encBytes {
+			i := 0
+			for i < len(enc) && i < len(encBytes) && enc[i] == encBytes[i] {
+				i++
+			}
+			enc = enc[i:]
+			encBytes = encBytes[i:]
+			i = 0
+			for i < len(enc) && i < len(encBytes) && enc[len(enc)-i-1] == encBytes[len(encBytes)-i-1] {
+				i++
+			}
+			enc = enc[:len(enc)-i]
+			encBytes = encBytes[:len(encBytes)-i]
+
+			if len(enc) > 20 {
+				enc = enc[:20] + "..."
+			}
+			if len(encBytes) > 20 {
+				encBytes = encBytes[:20] + "..."
+			}
 
-		t.Errorf("encodings differ at %#q vs %#q", enc, encBytes)
+			t.Errorf("with escapeHTML=%t, encodings differ at %#q vs %#q",
+				escapeHTML, enc, encBytes)
+		}
 	}
 }
 
@@ -536,3 +541,73 @@ func TestEncodeString(t *testing.T) {
 		}
 	}
 }
+
+type jsonbyte byte
+
+func (b jsonbyte) MarshalJSON() ([]byte, error) { return tenc(`{"JB":%d}`, b) }
+
+type textbyte byte
+
+func (b textbyte) MarshalText() ([]byte, error) { return tenc(`TB:%d`, b) }
+
+type jsonint int
+
+func (i jsonint) MarshalJSON() ([]byte, error) { return tenc(`{"JI":%d}`, i) }
+
+type textint int
+
+func (i textint) MarshalText() ([]byte, error) { return tenc(`TI:%d`, i) }
+
+func tenc(format string, a ...interface{}) ([]byte, error) {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, format, a...)
+	return buf.Bytes(), nil
+}
+
+// Issue 13783
+func TestEncodeBytekind(t *testing.T) {
+	testdata := []struct {
+		data interface{}
+		want string
+	}{
+		{byte(7), "7"},
+		{jsonbyte(7), `{"JB":7}`},
+		{textbyte(4), `"TB:4"`},
+		{jsonint(5), `{"JI":5}`},
+		{textint(1), `"TI:1"`},
+		{[]byte{0, 1}, `"AAE="`},
+		{[]jsonbyte{0, 1}, `[{"JB":0},{"JB":1}]`},
+		{[][]jsonbyte{{0, 1}, {3}}, `[[{"JB":0},{"JB":1}],[{"JB":3}]]`},
+		{[]textbyte{2, 3}, `["TB:2","TB:3"]`},
+		{[]jsonint{5, 4}, `[{"JI":5},{"JI":4}]`},
+		{[]textint{9, 3}, `["TI:9","TI:3"]`},
+		{[]int{9, 3}, `[9,3]`},
+	}
+	for _, d := range testdata {
+		js, err := Marshal(d.data)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		got, want := string(js), d.want
+		if got != want {
+			t.Errorf("got %s, want %s", got, want)
+		}
+	}
+}
+
+func TestTextMarshalerMapKeysAreSorted(t *testing.T) {
+	b, err := Marshal(map[unmarshalerText]int{
+		{"x", "y"}: 1,
+		{"y", "x"}: 2,
+		{"a", "z"}: 3,
+		{"z", "a"}: 4,
+	})
+	if err != nil {
+		t.Fatalf("Failed to Marshal text.Marshaler: %v", err)
+	}
+	const want = `{"a:z":3,"x:y":1,"y:x":2,"z:a":4}`
+	if string(b) != want {
+		t.Errorf("Marshal map with text.Marshaler keys: got %#q, want %#q", b, want)
+	}
+}
diff --git a/libgo/go/encoding/json/indent.go b/libgo/go/encoding/json/indent.go
index 7cd9f4db184..fba19548c92 100644
--- a/libgo/go/encoding/json/indent.go
+++ b/libgo/go/encoding/json/indent.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/json/number_test.go b/libgo/go/encoding/json/number_test.go
index 4e63cf9c74e..4b869996388 100644
--- a/libgo/go/encoding/json/number_test.go
+++ b/libgo/go/encoding/json/number_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/json/scanner.go b/libgo/go/encoding/json/scanner.go
index ee6622e8cf8..a6d8706c731 100644
--- a/libgo/go/encoding/json/scanner.go
+++ b/libgo/go/encoding/json/scanner.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -132,7 +132,7 @@ const (
 
 // These values are stored in the parseState stack.
 // They give the current state of a composite value
-// being scanned.  If the parser is inside a nested value
+// being scanned. If the parser is inside a nested value
 // the parseState describes the nested state, outermost at entry 0.
 const (
 	parseObjectKey   = iota // parsing object key (before colon)
diff --git a/libgo/go/encoding/json/scanner_test.go b/libgo/go/encoding/json/scanner_test.go
index 66383ef0ef7..70a28974f78 100644
--- a/libgo/go/encoding/json/scanner_test.go
+++ b/libgo/go/encoding/json/scanner_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/json/stream.go b/libgo/go/encoding/json/stream.go
index 8ddcf4d279e..87f0e57c6cd 100644
--- a/libgo/go/encoding/json/stream.go
+++ b/libgo/go/encoding/json/stream.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -10,7 +10,7 @@ import (
 	"io"
 )
 
-// A Decoder reads and decodes JSON objects from an input stream.
+// A Decoder reads and decodes JSON values from an input stream.
 type Decoder struct {
 	r     io.Reader
 	buf   []byte
@@ -148,7 +148,7 @@ func (dec *Decoder) refill() error {
 		dec.buf = newBuf
 	}
 
-	// Read.  Delay error for next iteration (after scan).
+	// Read. Delay error for next iteration (after scan).
 	n, err := dec.r.Read(dec.buf[len(dec.buf):cap(dec.buf)])
 	dec.buf = dec.buf[0 : len(dec.buf)+n]
 
@@ -164,15 +164,20 @@ func nonSpace(b []byte) bool {
 	return false
 }
 
-// An Encoder writes JSON objects to an output stream.
+// An Encoder writes JSON values to an output stream.
 type Encoder struct {
-	w   io.Writer
-	err error
+	w          io.Writer
+	err        error
+	escapeHTML bool
+
+	indentBuf    *bytes.Buffer
+	indentPrefix string
+	indentValue  string
 }
 
 // NewEncoder returns a new encoder that writes to w.
 func NewEncoder(w io.Writer) *Encoder {
-	return &Encoder{w: w}
+	return &Encoder{w: w, escapeHTML: true}
 }
 
 // Encode writes the JSON encoding of v to the stream,
@@ -185,7 +190,7 @@ func (enc *Encoder) Encode(v interface{}) error {
 		return enc.err
 	}
 	e := newEncodeState()
-	err := e.marshal(v)
+	err := e.marshal(v, encOpts{escapeHTML: enc.escapeHTML})
 	if err != nil {
 		return err
 	}
@@ -198,14 +203,45 @@ func (enc *Encoder) Encode(v interface{}) error {
 	// digits coming.
 	e.WriteByte('\n')
 
-	if _, err = enc.w.Write(e.Bytes()); err != nil {
+	b := e.Bytes()
+	if enc.indentPrefix != "" || enc.indentValue != "" {
+		if enc.indentBuf == nil {
+			enc.indentBuf = new(bytes.Buffer)
+		}
+		enc.indentBuf.Reset()
+		err = Indent(enc.indentBuf, b, enc.indentPrefix, enc.indentValue)
+		if err != nil {
+			return err
+		}
+		b = enc.indentBuf.Bytes()
+	}
+	if _, err = enc.w.Write(b); err != nil {
 		enc.err = err
 	}
 	encodeStatePool.Put(e)
 	return err
 }
 
-// RawMessage is a raw encoded JSON object.
+// SetIndent instructs the encoder to format each subsequent encoded
+// value as if indented by the package-level function Indent(dst, src, prefix, indent).
+// Calling SetIndent("", "") disables indentation.
+func (enc *Encoder) SetIndent(prefix, indent string) {
+	enc.indentPrefix = prefix
+	enc.indentValue = indent
+}
+
+// SetEscapeHTML specifies whether problematic HTML characters
+// should be escaped inside JSON quoted strings.
+// The default behavior is to escape &, <, and > to \u0026, \u003c, and \u003e
+// to avoid certain safety problems that can arise when embedding JSON in HTML.
+//
+// In non-HTML settings where the escaping interferes with the readability
+// of the output, SetEscapeHTML(false) disables this behavior.
+func (enc *Encoder) SetEscapeHTML(on bool) {
+	enc.escapeHTML = on
+}
+
+// RawMessage is a raw encoded JSON value.
 // It implements Marshaler and Unmarshaler and can
 // be used to delay JSON decoding or precompute a JSON encoding.
 type RawMessage []byte
diff --git a/libgo/go/encoding/json/stream_test.go b/libgo/go/encoding/json/stream_test.go
index c2e30408cd8..84edeb187c2 100644
--- a/libgo/go/encoding/json/stream_test.go
+++ b/libgo/go/encoding/json/stream_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -44,6 +44,9 @@ func TestEncoder(t *testing.T) {
 	for i := 0; i <= len(streamTest); i++ {
 		var buf bytes.Buffer
 		enc := NewEncoder(&buf)
+		// Check that enc.SetIndent("", "") turns off indentation.
+		enc.SetIndent(">", ".")
+		enc.SetIndent("", "")
 		for j, v := range streamTest[0:i] {
 			if err := enc.Encode(v); err != nil {
 				t.Fatalf("encode #%d: %v", j, err)
@@ -57,6 +60,69 @@ func TestEncoder(t *testing.T) {
 	}
 }
 
+var streamEncodedIndent = `0.1
+"hello"
+null
+true
+false
+[
+>."a",
+>."b",
+>."c"
+>]
+{
+>."ß": "long s",
+>."K": "Kelvin"
+>}
+3.14
+`
+
+func TestEncoderIndent(t *testing.T) {
+	var buf bytes.Buffer
+	enc := NewEncoder(&buf)
+	enc.SetIndent(">", ".")
+	for _, v := range streamTest {
+		enc.Encode(v)
+	}
+	if have, want := buf.String(), streamEncodedIndent; have != want {
+		t.Error("indented encoding mismatch")
+		diff(t, []byte(have), []byte(want))
+	}
+}
+
+func TestEncoderSetEscapeHTML(t *testing.T) {
+	var c C
+	var ct CText
+	for _, tt := range []struct {
+		name       string
+		v          interface{}
+		wantEscape string
+		want       string
+	}{
+		{"c", c, `"\u003c\u0026\u003e"`, `"<&>"`},
+		{"ct", ct, `"\"\u003c\u0026\u003e\""`, `"\"<&>\""`},
+		{`"<&>"`, "<&>", `"\u003c\u0026\u003e"`, `"<&>"`},
+	} {
+		var buf bytes.Buffer
+		enc := NewEncoder(&buf)
+		if err := enc.Encode(tt.v); err != nil {
+			t.Fatalf("Encode(%s): %s", tt.name, err)
+		}
+		if got := strings.TrimSpace(buf.String()); got != tt.wantEscape {
+			t.Errorf("Encode(%s) = %#q, want %#q", tt.name, got, tt.wantEscape)
+		}
+		buf.Reset()
+		enc.SetEscapeHTML(false)
+		if err := enc.Encode(tt.v); err != nil {
+			t.Fatalf("SetEscapeHTML(false) Encode(%s): %s", tt.name, err)
+		}
+		if got := strings.TrimSpace(buf.String()); got != tt.want {
+			t.Errorf("SetEscapeHTML(false) Encode(%s) = %#q, want %#q",
+				tt.name, got, tt.want)
+		}
+	}
+}
+
 func TestDecoder(t *testing.T) {
 	for i := 0; i <= len(streamTest); i++ {
 		// Use stream without newlines as input,
diff --git a/libgo/go/encoding/json/tagkey_test.go b/libgo/go/encoding/json/tagkey_test.go
index 85bb4ba8377..c1739ea97f7 100644
--- a/libgo/go/encoding/json/tagkey_test.go
+++ b/libgo/go/encoding/json/tagkey_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/json/tags_test.go b/libgo/go/encoding/json/tags_test.go
index 91fb18831e2..8ba8ddd5f80 100644
--- a/libgo/go/encoding/json/tags_test.go
+++ b/libgo/go/encoding/json/tags_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/pem/pem.go b/libgo/go/encoding/pem/pem.go
index 506196b1db9..ff2bed161ad 100644
--- a/libgo/go/encoding/pem/pem.go
+++ b/libgo/go/encoding/pem/pem.go
@@ -150,7 +150,7 @@ func Decode(data []byte) (p *Block, rest []byte) {
 func decodeError(data, rest []byte) (*Block, []byte) {
 	// If we get here then we have rejected a likely looking, but
 	// ultimately invalid PEM block. We need to start over from a new
-	// position.  We have consumed the preamble line and will have consumed
+	// position. We have consumed the preamble line and will have consumed
 	// any lines which could be header lines. However, a valid preamble
 	// line is not a valid header line, therefore we cannot have consumed
 	// the preamble line for the any subsequent block. Thus, we will always
diff --git a/libgo/go/encoding/xml/marshal.go b/libgo/go/encoding/xml/marshal.go
index 8ebd693030e..abb078ce270 100644
--- a/libgo/go/encoding/xml/marshal.go
+++ b/libgo/go/encoding/xml/marshal.go
@@ -26,14 +26,14 @@ const (
 //
 // Marshal handles an array or slice by marshalling each of the elements.
 // Marshal handles a pointer by marshalling the value it points at or, if the
-// pointer is nil, by writing nothing.  Marshal handles an interface value by
+// pointer is nil, by writing nothing. Marshal handles an interface value by
 // marshalling the value it contains or, if the interface value is nil, by
-// writing nothing.  Marshal handles all other data by writing one or more XML
+// writing nothing. Marshal handles all other data by writing one or more XML
 // elements containing the data.
 //
 // The name for the XML elements is taken from, in order of preference:
 //     - the tag on the XMLName field, if the data is a struct
-//     - the value of the XMLName field of type xml.Name
+//     - the value of the XMLName field of type Name
 //     - the tag of the struct field used to obtain the data
 //     - the name of the struct field used to obtain the data
 //     - the name of the marshalled type
@@ -63,7 +63,7 @@ const (
 //       value were part of the outer struct.
 //
 // If a field uses a tag "a>b>c", then the element c will be nested inside
-// parent elements a and b.  Fields that appear next to each other that name
+// parent elements a and b. Fields that appear next to each other that name
 // the same parent will be enclosed in one XML element.
 //
 // See MarshalIndent for an example.
@@ -175,10 +175,9 @@ func (enc *Encoder) EncodeElement(v interface{}, start StartElement) error {
 }
 
 var (
-	begComment   = []byte("<!--")
-	endComment   = []byte("-->")
-	endProcInst  = []byte("?>")
-	endDirective = []byte(">")
+	begComment  = []byte("<!--")
+	endComment  = []byte("-->")
+	endProcInst = []byte("?>")
 )
 
 // EncodeToken writes the given XML token to the stream.
@@ -217,7 +216,7 @@ func (enc *Encoder) EncodeToken(t Token) error {
 		return p.cachedWriteError()
 	case ProcInst:
 		// First token to be encoded which is also a ProcInst with target of xml
-		// is the xml declaration.  The only ProcInst where target of xml is allowed.
+		// is the xml declaration. The only ProcInst where target of xml is allowed.
 		if t.Target == "xml" && p.Buffered() != 0 {
 			return fmt.Errorf("xml: EncodeToken of ProcInst xml target only valid for xml declaration, first token encoded")
 		}
@@ -850,14 +849,14 @@ func (p *printer) marshalStruct(tinfo *typeInfo, val reflect.Value) error {
 			switch k {
 			case reflect.String:
 				s := vf.String()
-				dashDash = strings.Index(s, "--") >= 0
+				dashDash = strings.Contains(s, "--")
 				dashLast = s[len(s)-1] == '-'
 				if !dashDash {
 					p.WriteString(s)
 				}
 			case reflect.Slice:
 				b := vf.Bytes()
-				dashDash = bytes.Index(b, ddBytes) >= 0
+				dashDash = bytes.Contains(b, ddBytes)
 				dashLast = b[len(b)-1] == '-'
 				if !dashDash {
 					p.Write(b)
@@ -949,8 +948,8 @@ type parentStack struct {
 }
 
 // trim updates the XML context to match the longest common prefix of the stack
-// and the given parents.  A closing tag will be written for every parent
-// popped.  Passing a zero slice or nil will close all the elements.
+// and the given parents. A closing tag will be written for every parent
+// popped. Passing a zero slice or nil will close all the elements.
 func (s *parentStack) trim(parents []string) error {
 	split := 0
 	for ; split < len(parents) && split < len(s.stack); split++ {
diff --git a/libgo/go/encoding/xml/read.go b/libgo/go/encoding/xml/read.go
index 77b4c7b4955..937432e3a7e 100644
--- a/libgo/go/encoding/xml/read.go
+++ b/libgo/go/encoding/xml/read.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -27,7 +27,7 @@ import (
 // discarded.
 //
 // Because Unmarshal uses the reflect package, it can only assign
-// to exported (upper case) fields.  Unmarshal uses a case-sensitive
+// to exported (upper case) fields. Unmarshal uses a case-sensitive
 // comparison to match XML element names to tag values and struct
 // field names.
 //
@@ -37,9 +37,9 @@ import (
 //
 //   * If the struct has a field of type []byte or string with tag
 //      ",innerxml", Unmarshal accumulates the raw XML nested inside the
-//      element in that field.  The rest of the rules still apply.
+//      element in that field. The rest of the rules still apply.
 //
-//   * If the struct has a field named XMLName of type xml.Name,
+//   * If the struct has a field named XMLName of type Name,
 //      Unmarshal records the element name in that field.
 //
 //   * If the XMLName field has an associated tag of the form
@@ -59,7 +59,7 @@ import (
 //
 //   * If the XML element contains comments, they are accumulated in
 //      the first struct field that has tag ",comment".  The struct
-//      field may have type []byte or string.  If there is no such
+//      field may have type []byte or string. If there is no such
 //      field, the comments are discarded.
 //
 //   * If the XML element contains a sub-element whose name matches
@@ -102,11 +102,11 @@ import (
 //
 // Unmarshal maps an XML element or attribute value to an integer or
 // floating-point field by setting the field to the result of
-// interpreting the string value in decimal.  There is no check for
+// interpreting the string value in decimal. There is no check for
 // overflow.
 //
-// Unmarshal maps an XML element to an xml.Name by recording the
-// element name.
+// Unmarshal maps an XML element to a Name by recording the element
+// name.
 //
 // Unmarshal maps an XML element to a pointer by setting the pointer
 // to a freshly allocated value and then mapping the element to that value.
@@ -115,13 +115,13 @@ func Unmarshal(data []byte, v interface{}) error {
 	return NewDecoder(bytes.NewReader(data)).Decode(v)
 }
 
-// Decode works like xml.Unmarshal, except it reads the decoder
+// Decode works like Unmarshal, except it reads the decoder
 // stream to find the start element.
 func (d *Decoder) Decode(v interface{}) error {
 	return d.DecodeElement(v, nil)
 }
 
-// DecodeElement works like xml.Unmarshal except that it takes
+// DecodeElement works like Unmarshal except that it takes
 // a pointer to the start XML element to decode into v.
 // It is useful when a client reads some raw XML tokens itself
 // but also wants to defer to Unmarshal for some elements.
diff --git a/libgo/go/encoding/xml/typeinfo.go b/libgo/go/encoding/xml/typeinfo.go
index 6483c8dbe67..70da962ffaa 100644
--- a/libgo/go/encoding/xml/typeinfo.go
+++ b/libgo/go/encoding/xml/typeinfo.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/encoding/xml/xml.go b/libgo/go/encoding/xml/xml.go
index 45f4157318a..9a3b7929559 100644
--- a/libgo/go/encoding/xml/xml.go
+++ b/libgo/go/encoding/xml/xml.go
@@ -219,7 +219,7 @@ func NewDecoder(r io.Reader) *Decoder {
 //
 // Slices of bytes in the returned token data refer to the
 // parser's internal buffer and remain valid only until the next
-// call to Token.  To acquire a copy of the bytes, call CopyToken
+// call to Token. To acquire a copy of the bytes, call CopyToken
 // or the token's Copy method.
 //
 // Token expands self-closing elements such as <br/>
@@ -237,10 +237,11 @@ func NewDecoder(r io.Reader) *Decoder {
 // set to the URL identifying its name space when known.
 // If Token encounters an unrecognized name space prefix,
 // it uses the prefix as the Space rather than report an error.
-func (d *Decoder) Token() (t Token, err error) {
+func (d *Decoder) Token() (Token, error) {
+	var t Token
+	var err error
 	if d.stk != nil && d.stk.kind == stkEOF {
-		err = io.EOF
-		return
+		return nil, io.EOF
 	}
 	if d.nextToken != nil {
 		t = d.nextToken
@@ -249,7 +250,7 @@ func (d *Decoder) Token() (t Token, err error) {
 		if err == io.EOF && d.stk != nil && d.stk.kind != stkEOF {
 			err = d.syntaxError("unexpected EOF")
 		}
-		return
+		return t, err
 	}
 
 	if !d.Strict {
@@ -292,7 +293,7 @@ func (d *Decoder) Token() (t Token, err error) {
 		}
 		t = t1
 	}
-	return
+	return t, err
 }
 
 const xmlURL = "http://www.w3.org/XML/1998/namespace"
@@ -331,7 +332,7 @@ func (d *Decoder) switchToReader(r io.Reader) {
 }
 
 // Parsing state - stack holds old name space translations
-// and the current set of open elements.  The translations to pop when
+// and the current set of open elements. The translations to pop when
 // ending a given tag are *below* it on the stack, which is
 // more work but forced on us by XML.
 type stack struct {
@@ -1229,7 +1230,7 @@ func isNameString(s string) bool {
 
 // These tables were generated by cut and paste from Appendix B of
 // the XML spec at http://www.xml.com/axml/testaxml.htm
-// and then reformatting.  First corresponds to (Letter | '_' | ':')
+// and then reformatting. First corresponds to (Letter | '_' | ':')
 // and second corresponds to NameChar.
 
 var first = &unicode.RangeTable{
diff --git a/libgo/go/encoding/xml/xml_test.go b/libgo/go/encoding/xml/xml_test.go
index 5d5e4bf9709..dad6ed98c1b 100644
--- a/libgo/go/encoding/xml/xml_test.go
+++ b/libgo/go/encoding/xml/xml_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -184,8 +184,6 @@ const nonStrictInput = `
 <tag>&0a;</tag>
 `
 
-var nonStringEntity = map[string]string{"": "oops!", "0a": "oops!"}
-
 var nonStrictTokens = []Token{
 	CharData("\n"),
 	StartElement{Name{"", "tag"}, []Attr{}},
@@ -652,10 +650,6 @@ func TestDisallowedCharacters(t *testing.T) {
 	}
 }
 
-type procInstEncodingTest struct {
-	expect, got string
-}
-
 var procInstTests = []struct {
 	input  string
 	expect [2]string
diff --git a/libgo/go/errors/errors.go b/libgo/go/errors/errors.go
index 3085a7962c2..b8a46921be0 100644
--- a/libgo/go/errors/errors.go
+++ b/libgo/go/errors/errors.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/errors/errors_test.go b/libgo/go/errors/errors_test.go
index 63c05d7185b..cf4df90b695 100644
--- a/libgo/go/errors/errors_test.go
+++ b/libgo/go/errors/errors_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/expvar/expvar.go b/libgo/go/expvar/expvar.go
index 24c2d6b29ab..d5465c518f8 100644
--- a/libgo/go/expvar/expvar.go
+++ b/libgo/go/expvar/expvar.go
@@ -15,7 +15,7 @@
 //	memstats  runtime.Memstats
 //
 // The package is sometimes only imported for the side effect of
-// registering its HTTP handler and the above variables.  To use it
+// registering its HTTP handler and the above variables. To use it
 // this way, link this package into your program:
 //	import _ "expvar"
 //
@@ -38,6 +38,9 @@ import (
 
 // Var is an abstract type for all exported variables.
 type Var interface {
+	// String returns a valid JSON value for the variable.
+	// Types with String methods that do not return valid JSON
+	// (such as time.Time) must not be used as a Var.
 	String() string
 }
 
@@ -218,8 +221,10 @@ type String struct {
 
 func (v *String) String() string {
 	v.mu.RLock()
-	defer v.mu.RUnlock()
-	return strconv.Quote(v.s)
+	s := v.s
+	v.mu.RUnlock()
+	b, _ := json.Marshal(s)
+	return string(b)
 }
 
 func (v *String) Set(value string) {
@@ -258,7 +263,8 @@ func Publish(name string, v Var) {
 	sort.Strings(varKeys)
 }
 
-// Get retrieves a named exported variable.
+// Get retrieves a named exported variable. It returns nil if the name has
+// not been registered.
 func Get(name string) Var {
 	mutex.RLock()
 	defer mutex.RUnlock()
diff --git a/libgo/go/expvar/expvar_test.go b/libgo/go/expvar/expvar_test.go
index 8bc633e4a97..7b1c9dfc4f8 100644
--- a/libgo/go/expvar/expvar_test.go
+++ b/libgo/go/expvar/expvar_test.go
@@ -26,6 +26,14 @@ func RemoveAll() {
 	varKeys = nil
 }
 
+func TestNil(t *testing.T) {
+	RemoveAll()
+	val := Get("missing")
+	if val != nil {
+		t.Errorf("got %v, want nil", val)
+	}
+}
+
 func TestInt(t *testing.T) {
 	RemoveAll()
 	reqs := NewInt("requests")
@@ -134,8 +142,14 @@ func TestString(t *testing.T) {
 		t.Errorf("name.s = %q, want \"Mike\"", name.s)
 	}
 
-	if s := name.String(); s != "\"Mike\"" {
-		t.Errorf("reqs.String() = %q, want \"\"Mike\"\"", s)
+	if s, want := name.String(), `"Mike"`; s != want {
+		t.Errorf("from %q, name.String() = %q, want %q", name.s, s, want)
+	}
+
+	// Make sure we produce safe JSON output.
+	name.Set(`<`)
+	if s, want := name.String(), "\"\\u003c\""; s != want {
+		t.Errorf("from %q, name.String() = %q, want %q", name.s, s, want)
 	}
 }
 
diff --git a/libgo/go/flag/export_test.go b/libgo/go/flag/export_test.go
index 56cda58b36c..12d3dc76dfe 100644
--- a/libgo/go/flag/export_test.go
+++ b/libgo/go/flag/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/flag/flag.go b/libgo/go/flag/flag.go
index 3abc80e9c67..fa0f05e9683 100644
--- a/libgo/go/flag/flag.go
+++ b/libgo/go/flag/flag.go
@@ -68,6 +68,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"reflect"
 	"sort"
 	"strconv"
 	"time"
@@ -261,7 +262,7 @@ const (
 	PanicOnError                         // Call panic with a descriptive error.
 )
 
-// A FlagSet represents a set of defined flags.  The zero value of a FlagSet
+// A FlagSet represents a set of defined flags. The zero value of a FlagSet
 // has no name and has ContinueOnError error handling.
 type FlagSet struct {
 	// Usage is the function called when an error occurs while parsing flags.
@@ -324,7 +325,7 @@ func (f *FlagSet) VisitAll(fn func(*Flag)) {
 }
 
 // VisitAll visits the command-line flags in lexicographical order, calling
-// fn for each.  It visits all flags, even those not set.
+// fn for each. It visits all flags, even those not set.
 func VisitAll(fn func(*Flag)) {
 	CommandLine.VisitAll(fn)
 }
@@ -338,7 +339,7 @@ func (f *FlagSet) Visit(fn func(*Flag)) {
 }
 
 // Visit visits the command-line flags in lexicographical order, calling fn
-// for each.  It visits only those flags that have been set.
+// for each. It visits only those flags that have been set.
 func Visit(fn func(*Flag)) {
 	CommandLine.Visit(fn)
 }
@@ -378,7 +379,21 @@ func Set(name, value string) error {
 
 // isZeroValue guesses whether the string represents the zero
 // value for a flag. It is not accurate but in practice works OK.
-func isZeroValue(value string) bool {
+func isZeroValue(flag *Flag, value string) bool {
+	// Build a zero value of the flag's Value type, and see if the
+	// result of calling its String method equals the value passed in.
+	// This works unless the Value type is itself an interface type.
+	typ := reflect.TypeOf(flag.Value)
+	var z reflect.Value
+	if typ.Kind() == reflect.Ptr {
+		z = reflect.New(typ.Elem())
+	} else {
+		z = reflect.Zero(typ)
+	}
+	if value == z.Interface().(Value).String() {
+		return true
+	}
+
 	switch value {
 	case "false":
 		return true
@@ -449,7 +464,7 @@ func (f *FlagSet) PrintDefaults() {
 			s += "\n    \t"
 		}
 		s += usage
-		if !isZeroValue(flag.DefValue) {
+		if !isZeroValue(flag, flag.DefValue) {
 			if _, ok := flag.Value.(*stringValue); ok {
 				// put quotes on the value
 				s += fmt.Sprintf(" (default %q)", flag.DefValue)
@@ -514,7 +529,7 @@ func (f *FlagSet) NFlag() int { return len(f.actual) }
 // NFlag returns the number of command-line flags that have been set.
 func NFlag() int { return len(CommandLine.actual) }
 
-// Arg returns the i'th argument.  Arg(0) is the first remaining argument
+// Arg returns the i'th argument. Arg(0) is the first remaining argument
 // after flags have been processed. Arg returns an empty string if the
 // requested element does not exist.
 func (f *FlagSet) Arg(i int) string {
@@ -524,7 +539,7 @@ func (f *FlagSet) Arg(i int) string {
 	return f.args[i]
 }
 
-// Arg returns the i'th command-line argument.  Arg(0) is the first remaining argument
+// Arg returns the i'th command-line argument. Arg(0) is the first remaining argument
 // after flags have been processed. Arg returns an empty string if the
 // requested element does not exist.
 func Arg(i int) string {
@@ -890,7 +905,7 @@ func (f *FlagSet) parseOne() (bool, error) {
 }
 
 // Parse parses flag definitions from the argument list, which should not
-// include the command name.  Must be called after all flags in the FlagSet
+// include the command name. Must be called after all flags in the FlagSet
 // are defined and before flags are accessed by the program.
 // The return value will be ErrHelp if -help or -h were set but not defined.
 func (f *FlagSet) Parse(arguments []string) error {
diff --git a/libgo/go/fmt/doc.go b/libgo/go/fmt/doc.go
index 4eea48eb6b0..c312914b44a 100644
--- a/libgo/go/fmt/doc.go
+++ b/libgo/go/fmt/doc.go
@@ -62,7 +62,7 @@
 	For compound objects, the elements are printed using these rules, recursively,
 	laid out like this:
 		struct:             {field0 field1 ...}
-		array, slice:       [elem0  elem1 ...]
+		array, slice:       [elem0 elem1 ...]
 		maps:               map[key1:value1 key2:value2]
 		pointer to above:   &{}, &[], &map[]
 
@@ -95,10 +95,10 @@
 
 	For floating-point values, width sets the minimum width of the field and
 	precision sets the number of places after the decimal, if appropriate,
-	except that for %g/%G it sets the total number of digits. For example,
-	given 123.45 the format %6.2f prints 123.45 while %.4g prints 123.5.
-	The default precision for %e and %f is 6; for %g it is the smallest
-	number of digits necessary to identify the value uniquely.
+	except that for %g/%G precision sets the total number of significant
+	digits. For example, given 12.345 the format %6.3f prints 12.345 while
+	%.3g prints 12.3. The default precision for %e and %f is 6; for %g it
+	is the smallest number of digits necessary to identify the value uniquely.
 
 	For complex numbers, the width and precision apply to the two
 	components independently and the result is parenthesized, so %f applied
@@ -210,7 +210,7 @@
 		Too many arguments: %!(EXTRA type=value)
 			Printf("hi", "guys"):      hi%!(EXTRA string=guys)
 		Too few arguments: %!verb(MISSING)
-			Printf("hi%d"):            hi %!d(MISSING)
+			Printf("hi%d"):            hi%!d(MISSING)
 		Non-int for width or precision: %!(BADWIDTH) or %!(BADPREC)
 			Printf("%*s", 4.5, "hi"):  %!(BADWIDTH)hi
 			Printf("%.*s", 4.5, "hi"): %!(BADPREC)hi
diff --git a/libgo/go/fmt/export_test.go b/libgo/go/fmt/export_test.go
index 89d57ee6ce3..12d5a1130a4 100644
--- a/libgo/go/fmt/export_test.go
+++ b/libgo/go/fmt/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/fmt/fmt_test.go b/libgo/go/fmt/fmt_test.go
index ea6392feb6b..b6582367673 100644
--- a/libgo/go/fmt/fmt_test.go
+++ b/libgo/go/fmt/fmt_test.go
@@ -48,13 +48,18 @@ func TestFmtInterface(t *testing.T) {
 	}
 }
 
-const b32 uint32 = 1<<32 - 1
-const b64 uint64 = 1<<64 - 1
+var (
+	NaN    = math.NaN()
+	posInf = math.Inf(1)
+	negInf = math.Inf(-1)
 
-var array = [5]int{1, 2, 3, 4, 5}
-var iarray = [4]interface{}{1, "hello", 2.5, nil}
-var slice = array[:]
-var islice = iarray[:]
+	intVar = 0
+
+	array  = [5]int{1, 2, 3, 4, 5}
+	iarray = [4]interface{}{1, "hello", 2.5, nil}
+	slice  = array[:]
+	islice = iarray[:]
+)
 
 type A struct {
 	i int
@@ -112,9 +117,11 @@ var bslice = barray[:]
 
 type byteStringer byte
 
-func (byteStringer) String() string { return "X" }
+func (byteStringer) String() string {
+	return "X"
+}
 
-var byteStringerSlice = []byteStringer{97, 98, 99, 100}
+var byteStringerSlice = []byteStringer{'h', 'e', 'l', 'l', 'o'}
 
 type byteFormatter byte
 
@@ -122,9 +129,7 @@ func (byteFormatter) Format(f State, _ rune) {
 	Fprint(f, "X")
 }
 
-var byteFormatterSlice = []byteFormatter{97, 98, 99, 100}
-
-var b byte
+var byteFormatterSlice = []byteFormatter{'h', 'e', 'l', 'l', 'o'}
 
 var fmtTests = []struct {
 	fmt string
@@ -141,6 +146,10 @@ var fmtTests = []struct {
 	{"%x", "abc", "616263"},
 	{"%x", "\xff\xf0\x0f\xff", "fff00fff"},
 	{"%X", "\xff\xf0\x0f\xff", "FFF00FFF"},
+	{"%x", "", ""},
+	{"% x", "", ""},
+	{"%#x", "", ""},
+	{"%# x", "", ""},
 	{"%x", "xyz", "78797a"},
 	{"%X", "xyz", "78797A"},
 	{"% x", "xyz", "78 79 7a"},
@@ -152,10 +161,16 @@ var fmtTests = []struct {
 
 	// basic bytes
 	{"%s", []byte("abc"), "abc"},
+	{"%s", [3]byte{'a', 'b', 'c'}, "abc"},
+	{"%s", &[3]byte{'a', 'b', 'c'}, "&abc"},
 	{"%q", []byte("abc"), `"abc"`},
 	{"%x", []byte("abc"), "616263"},
 	{"%x", []byte("\xff\xf0\x0f\xff"), "fff00fff"},
 	{"%X", []byte("\xff\xf0\x0f\xff"), "FFF00FFF"},
+	{"%x", []byte(""), ""},
+	{"% x", []byte(""), ""},
+	{"%#x", []byte(""), ""},
+	{"%# x", []byte(""), ""},
 	{"%x", []byte("xyz"), "78797a"},
 	{"%X", []byte("xyz"), "78797A"},
 	{"% x", []byte("xyz"), "78 79 7a"},
@@ -166,29 +181,112 @@ var fmtTests = []struct {
 	{"%# X", []byte("xyz"), "0X78 0X79 0X7A"},
 
 	// escaped strings
-	{"%#q", `abc`, "`abc`"},
-	{"%#q", `"`, "`\"`"},
-	{"1 %#q", `\n`, "1 `\\n`"},
-	{"2 %#q", "\n", `2 "\n"`},
-	{"%q", `"`, `"\""`},
-	{"%q", "\a\b\f\r\n\t\v", `"\a\b\f\r\n\t\v"`},
+	{"%q", "", `""`},
+	{"%#q", "", "``"},
+	{"%q", "\"", `"\""`},
+	{"%#q", "\"", "`\"`"},
+	{"%q", "`", `"` + "`" + `"`},
+	{"%#q", "`", `"` + "`" + `"`},
+	{"%q", "\n", `"\n"`},
+	{"%#q", "\n", `"\n"`},
+	{"%q", `\n`, `"\\n"`},
+	{"%#q", `\n`, "`\\n`"},
+	{"%q", "abc", `"abc"`},
+	{"%#q", "abc", "`abc`"},
+	{"%q", "日本語", `"日本語"`},
+	{"%+q", "日本語", `"\u65e5\u672c\u8a9e"`},
+	{"%#q", "日本語", "`日本語`"},
+	{"%#+q", "日本語", "`日本語`"},
+	{"%q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+	{"%+q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+	{"%#q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+	{"%#+q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+	{"%q", "☺", `"☺"`},
+	{"% q", "☺", `"☺"`}, // The space modifier should have no effect.
+	{"%+q", "☺", `"\u263a"`},
+	{"%#q", "☺", "`☺`"},
+	{"%#+q", "☺", "`☺`"},
+	{"%10q", "⌘", `       "⌘"`},
+	{"%+10q", "⌘", `  "\u2318"`},
+	{"%-10q", "⌘", `"⌘"       `},
+	{"%+-10q", "⌘", `"\u2318"  `},
+	{"%010q", "⌘", `0000000"⌘"`},
+	{"%+010q", "⌘", `00"\u2318"`},
+	{"%-010q", "⌘", `"⌘"       `}, // 0 has no effect when - is present.
+	{"%+-010q", "⌘", `"\u2318"  `},
+	{"%#8q", "\n", `    "\n"`},
+	{"%#+8q", "\r", `    "\r"`},
+	{"%#-8q", "\t", "`	`     "},
+	{"%#+-8q", "\b", `"\b"    `},
 	{"%q", "abc\xffdef", `"abc\xffdef"`},
-	{"%q", "\u263a", `"☺"`},
-	{"%+q", "\u263a", `"\u263a"`},
+	{"%+q", "abc\xffdef", `"abc\xffdef"`},
+	{"%#q", "abc\xffdef", `"abc\xffdef"`},
+	{"%#+q", "abc\xffdef", `"abc\xffdef"`},
+	// Runes that are not printable.
 	{"%q", "\U0010ffff", `"\U0010ffff"`},
+	{"%+q", "\U0010ffff", `"\U0010ffff"`},
+	{"%#q", "\U0010ffff", "`􏿿`"},
+	{"%#+q", "\U0010ffff", "`􏿿`"},
+	// Runes that are not valid.
+	{"%q", string(0x110000), `"�"`},
+	{"%+q", string(0x110000), `"\ufffd"`},
+	{"%#q", string(0x110000), "`�`"},
+	{"%#+q", string(0x110000), "`�`"},
+
+	// characters
+	{"%c", uint('x'), "x"},
+	{"%c", 0xe4, "ä"},
+	{"%c", 0x672c, "本"},
+	{"%c", '日', "日"},
+	{"%.0c", '⌘', "⌘"}, // Specifying precision should have no effect.
+	{"%3c", '⌘', "  ⌘"},
+	{"%-3c", '⌘', "⌘  "},
+	// Runes that are not printable.
+	{"%c", '\U00000e00', "\u0e00"},
+	{"%c", '\U0010ffff', "\U0010ffff"},
+	// Runes that are not valid.
+	{"%c", -1, "�"},
+	{"%c", 0xDC80, "�"},
+	{"%c", rune(0x110000), "�"},
+	{"%c", int64(0xFFFFFFFFF), "�"},
+	{"%c", uint64(0xFFFFFFFFF), "�"},
 
 	// escaped characters
-	{"%q", 'x', `'x'`},
-	{"%q", 0, `'\x00'`},
-	{"%q", '\n', `'\n'`},
-	{"%q", '\u0e00', `'\u0e00'`},         // not a printable rune.
-	{"%q", '\U000c2345', `'\U000c2345'`}, // not a printable rune.
-	{"%q", int64(0x7FFFFFFF), `%!q(int64=2147483647)`},
-	{"%q", uint64(0xFFFFFFFF), `%!q(uint64=4294967295)`},
+	{"%q", uint(0), `'\x00'`},
+	{"%+q", uint(0), `'\x00'`},
 	{"%q", '"', `'"'`},
+	{"%+q", '"', `'"'`},
 	{"%q", '\'', `'\''`},
-	{"%q", "\u263a", `"☺"`},
-	{"%+q", "\u263a", `"\u263a"`},
+	{"%+q", '\'', `'\''`},
+	{"%q", '`', "'`'"},
+	{"%+q", '`', "'`'"},
+	{"%q", 'x', `'x'`},
+	{"%+q", 'x', `'x'`},
+	{"%q", 'ÿ', `'ÿ'`},
+	{"%+q", 'ÿ', `'\u00ff'`},
+	{"%q", '\n', `'\n'`},
+	{"%+q", '\n', `'\n'`},
+	{"%q", '☺', `'☺'`},
+	{"%+q", '☺', `'\u263a'`},
+	{"% q", '☺', `'☺'`},  // The space modifier should have no effect.
+	{"%.0q", '☺', `'☺'`}, // Specifying precision should have no effect.
+	{"%10q", '⌘', `       '⌘'`},
+	{"%+10q", '⌘', `  '\u2318'`},
+	{"%-10q", '⌘', `'⌘'       `},
+	{"%+-10q", '⌘', `'\u2318'  `},
+	{"%010q", '⌘', `0000000'⌘'`},
+	{"%+010q", '⌘', `00'\u2318'`},
+	{"%-010q", '⌘', `'⌘'       `}, // 0 has no effect when - is present.
+	{"%+-010q", '⌘', `'\u2318'  `},
+	// Runes that are not printable.
+	{"%q", '\U00000e00', `'\u0e00'`},
+	{"%q", '\U0010ffff', `'\U0010ffff'`},
+	// Runes that are not valid.
+	{"%q", int32(-1), "%!q(int32=-1)"},
+	{"%q", 0xDC80, `'�'`},
+	{"%q", rune(0x110000), "%!q(int32=1114112)"},
+	{"%q", int64(0xFFFFFFFFF), "%!q(int64=68719476735)"},
+	{"%q", uint64(0xFFFFFFFFF), "%!q(uint64=68719476735)"},
 
 	// width
 	{"%5s", "abc", "  abc"},
@@ -199,57 +297,99 @@ var fmtTests = []struct {
 	{"%08q", "abc", `000"abc"`},
 	{"%5s", "abcdefghijklmnopqrstuvwxyz", "abcdefghijklmnopqrstuvwxyz"},
 	{"%.5s", "abcdefghijklmnopqrstuvwxyz", "abcde"},
+	{"%.0s", "日本語日本語", ""},
 	{"%.5s", "日本語日本語", "日本語日本"},
+	{"%.10s", "日本語日本語", "日本語日本語"},
 	{"%.5s", []byte("日本語日本語"), "日本語日本"},
 	{"%.5q", "abcdefghijklmnopqrstuvwxyz", `"abcde"`},
-	{"%.5x", "abcdefghijklmnopqrstuvwxyz", `6162636465`},
+	{"%.5x", "abcdefghijklmnopqrstuvwxyz", "6162636465"},
 	{"%.5q", []byte("abcdefghijklmnopqrstuvwxyz"), `"abcde"`},
-	{"%.5x", []byte("abcdefghijklmnopqrstuvwxyz"), `6162636465`},
+	{"%.5x", []byte("abcdefghijklmnopqrstuvwxyz"), "6162636465"},
 	{"%.3q", "日本語日本語", `"日本語"`},
 	{"%.3q", []byte("日本語日本語"), `"日本語"`},
 	{"%.1q", "日本語", `"日"`},
 	{"%.1q", []byte("日本語"), `"日"`},
-	{"%.1x", "日本語", `e6`},
-	{"%.1X", []byte("日本語"), `E6`},
+	{"%.1x", "日本語", "e6"},
+	{"%.1X", []byte("日本語"), "E6"},
 	{"%10.1q", "日本語日本語", `       "日"`},
-	{"%3c", '⌘', "  ⌘"},
-	{"%5q", '\u2026', `  '…'`},
 	{"%10v", nil, "     <nil>"},
 	{"%-10v", nil, "<nil>     "},
 
 	// integers
-	{"%d", 12345, "12345"},
-	{"%d", -12345, "-12345"},
+	{"%d", uint(12345), "12345"},
+	{"%d", int(-12345), "-12345"},
+	{"%d", ^uint8(0), "255"},
+	{"%d", ^uint16(0), "65535"},
+	{"%d", ^uint32(0), "4294967295"},
+	{"%d", ^uint64(0), "18446744073709551615"},
+	{"%d", int8(-1 << 7), "-128"},
+	{"%d", int16(-1 << 15), "-32768"},
+	{"%d", int32(-1 << 31), "-2147483648"},
+	{"%d", int64(-1 << 63), "-9223372036854775808"},
+	{"%.d", 0, ""},
+	{"%.0d", 0, ""},
+	{"%6.0d", 0, "      "},
+	{"%06.0d", 0, "      "},
+	{"% d", 12345, " 12345"},
+	{"%+d", 12345, "+12345"},
+	{"%+d", -12345, "-12345"},
+	{"%b", 7, "111"},
+	{"%b", -6, "-110"},
+	{"%b", ^uint32(0), "11111111111111111111111111111111"},
+	{"%b", ^uint64(0), "1111111111111111111111111111111111111111111111111111111111111111"},
+	{"%b", int64(-1 << 63), zeroFill("-1", 63, "")},
+	{"%o", 01234, "1234"},
+	{"%#o", 01234, "01234"},
+	{"%o", ^uint32(0), "37777777777"},
+	{"%o", ^uint64(0), "1777777777777777777777"},
+	{"%#X", 0, "0X0"},
+	{"%x", 0x12abcdef, "12abcdef"},
+	{"%X", 0x12abcdef, "12ABCDEF"},
+	{"%x", ^uint32(0), "ffffffff"},
+	{"%X", ^uint64(0), "FFFFFFFFFFFFFFFF"},
+	{"%.20b", 7, "00000000000000000111"},
 	{"%10d", 12345, "     12345"},
 	{"%10d", -12345, "    -12345"},
 	{"%+10d", 12345, "    +12345"},
 	{"%010d", 12345, "0000012345"},
 	{"%010d", -12345, "-000012345"},
-	{"%-10d", 12345, "12345     "},
-	{"%010.3d", 1, "       001"},
-	{"%010.3d", -1, "      -001"},
-	{"%+d", 12345, "+12345"},
-	{"%+d", -12345, "-12345"},
-	{"%+d", 0, "+0"},
-	{"% d", 0, " 0"},
-	{"% d", 12345, " 12345"},
-	{"%.0d", 0, ""},
-	{"%.d", 0, ""},
+	{"%20.8d", 1234, "            00001234"},
+	{"%20.8d", -1234, "           -00001234"},
+	{"%020.8d", 1234, "            00001234"},
+	{"%020.8d", -1234, "           -00001234"},
+	{"%-20.8d", 1234, "00001234            "},
+	{"%-20.8d", -1234, "-00001234           "},
+	{"%-#20.8x", 0x1234abc, "0x01234abc          "},
+	{"%-#20.8X", 0x1234abc, "0X01234ABC          "},
+	{"%-#20.8o", 01234, "00001234            "},
+
+	// Test correct f.intbuf overflow checks.
+	{"%068d", 1, zeroFill("", 68, "1")},
+	{"%068d", -1, zeroFill("-", 67, "1")},
+	{"%#.68x", 42, zeroFill("0x", 68, "2a")},
+	{"%.68d", -42, zeroFill("-", 68, "42")},
+	{"%+.68d", 42, zeroFill("+", 68, "42")},
+	{"% .68d", 42, zeroFill(" ", 68, "42")},
+	{"% +.68d", 42, zeroFill("+", 68, "42")},
 
 	// unicode format
-	{"%U", 0x1, "U+0001"},
-	{"%U", uint(0x1), "U+0001"},
-	{"%.8U", 0x2, "U+00000002"},
-	{"%U", 0x1234, "U+1234"},
-	{"%U", 0x12345, "U+12345"},
-	{"%10.6U", 0xABC, "  U+000ABC"},
-	{"%-10.6U", 0xABC, "U+000ABC  "},
+	{"%U", 0, "U+0000"},
+	{"%U", -1, "U+FFFFFFFFFFFFFFFF"},
 	{"%U", '\n', `U+000A`},
 	{"%#U", '\n', `U+000A`},
-	{"%U", 'x', `U+0078`},
-	{"%#U", 'x', `U+0078 'x'`},
+	{"%+U", 'x', `U+0078`},       // Plus flag should have no effect.
+	{"%# U", 'x', `U+0078 'x'`},  // Space flag should have no effect.
+	{"%#.2U", 'x', `U+0078 'x'`}, // Precisions below 4 should print 4 digits.
 	{"%U", '\u263a', `U+263A`},
 	{"%#U", '\u263a', `U+263A '☺'`},
+	{"%U", '\U0001D6C2', `U+1D6C2`},
+	{"%#U", '\U0001D6C2', `U+1D6C2 '𝛂'`},
+	{"%#14.6U", '⌘', "  U+002318 '⌘'"},
+	{"%#-14.6U", '⌘', "U+002318 '⌘'  "},
+	{"%#014.6U", '⌘', "  U+002318 '⌘'"},
+	{"%#-014.6U", '⌘', "U+002318 '⌘'  "},
+	{"%.68U", uint(42), zeroFill("U+", 68, "2A")},
+	{"%#.68U", '日', zeroFill("U+", 68, "65E5") + " '日'"},
 
 	// floats
 	{"%+.3e", 0.0, "+0.000e+00"},
@@ -259,6 +399,12 @@ var fmtTests = []struct {
 	{"%+.3F", float32(-1.0), "-1.000"},
 	{"%+07.2f", 1.0, "+001.00"},
 	{"%+07.2f", -1.0, "-001.00"},
+	{"%-07.2f", 1.0, "1.00   "},
+	{"%-07.2f", -1.0, "-1.00  "},
+	{"%+-07.2f", 1.0, "+1.00  "},
+	{"%+-07.2f", -1.0, "-1.00  "},
+	{"%-+07.2f", 1.0, "+1.00  "},
+	{"%-+07.2f", -1.0, "-1.00  "},
 	{"%+10.2f", +1.0, "     +1.00"},
 	{"%+10.2f", -1.0, "     -1.00"},
 	{"% .3E", -1.0, "-1.000E+00"},
@@ -270,8 +416,36 @@ var fmtTests = []struct {
 	{"% .3g", 1.0, " 1"},
 	{"%b", float32(1.0), "8388608p-23"},
 	{"%b", 1.0, "4503599627370496p-52"},
+	// Precision has no effect for binary float format.
+	{"%.4b", float32(1.0), "8388608p-23"},
+	{"%.4b", -1.0, "-4503599627370496p-52"},
+	// Test correct f.intbuf boundary checks.
+	{"%.68f", 1.0, zeroFill("1.", 68, "")},
+	{"%.68f", -1.0, zeroFill("-1.", 68, "")},
+	// float infinites and NaNs
+	{"%f", posInf, "+Inf"},
+	{"%.1f", negInf, "-Inf"},
+	{"% f", NaN, " NaN"},
+	{"%20f", posInf, "                +Inf"},
+	{"% 20F", posInf, "                 Inf"},
+	{"% 20e", negInf, "                -Inf"},
+	{"%+20E", negInf, "                -Inf"},
+	{"% +20g", negInf, "                -Inf"},
+	{"%+-20G", posInf, "+Inf                "},
+	{"%20e", NaN, "                 NaN"},
+	{"% +20E", NaN, "                +NaN"},
+	{"% -20g", NaN, " NaN                "},
+	{"%+-20G", NaN, "+NaN                "},
+	// Zero padding does not apply to infinities and NaN.
+	{"%+020e", posInf, "                +Inf"},
+	{"%-020f", negInf, "-Inf                "},
+	{"%-020E", NaN, "NaN                 "},
 
 	// complex values
+	{"%.f", 0i, "(0+0i)"},
+	{"% .f", 0i, "( 0+0i)"},
+	{"%+.f", 0i, "(+0+0i)"},
+	{"% +.f", 0i, "(+0+0i)"},
 	{"%+.3e", 0i, "(+0.000e+00+0.000e+00i)"},
 	{"%+.3f", 0i, "(+0.000+0.000i)"},
 	{"%+.3g", 0i, "(+0+0i)"},
@@ -290,35 +464,33 @@ var fmtTests = []struct {
 	{"%.3f", -1 - 2i, "(-1.000-2.000i)"},
 	{"%.3g", -1 - 2i, "(-1-2i)"},
 	{"% .3E", -1 - 2i, "(-1.000E+00-2.000E+00i)"},
+	{"%+.3g", 1 + 2i, "(+1+2i)"},
 	{"%+.3g", complex64(1 + 2i), "(+1+2i)"},
-	{"%+.3g", complex128(1 + 2i), "(+1+2i)"},
-	{"%b", complex64(1 + 2i), "(8388608p-23+8388608p-22i)"},
 	{"%b", 1 + 2i, "(4503599627370496p-52+4503599627370496p-51i)"},
-
-	// erroneous formats
-	{"", 2, "%!(EXTRA int=2)"},
-	{"%d", "hello", "%!d(string=hello)"},
+	{"%b", complex64(1 + 2i), "(8388608p-23+8388608p-22i)"},
+	// Precision has no effect for binary complex format.
+	{"%.4b", 1 + 2i, "(4503599627370496p-52+4503599627370496p-51i)"},
+	{"%.4b", complex64(1 + 2i), "(8388608p-23+8388608p-22i)"},
+	// complex infinites and NaNs
+	{"%f", complex(posInf, posInf), "(+Inf+Infi)"},
+	{"%f", complex(negInf, negInf), "(-Inf-Infi)"},
+	{"%f", complex(NaN, NaN), "(NaN+NaNi)"},
+	{"%.1f", complex(posInf, posInf), "(+Inf+Infi)"},
+	{"% f", complex(posInf, posInf), "( Inf+Infi)"},
+	{"% f", complex(negInf, negInf), "(-Inf-Infi)"},
+	{"% f", complex(NaN, NaN), "( NaN+NaNi)"},
+	{"%8e", complex(posInf, posInf), "(    +Inf    +Infi)"},
+	{"% 8E", complex(posInf, posInf), "(     Inf    +Infi)"},
+	{"%+8f", complex(negInf, negInf), "(    -Inf    -Infi)"},
+	{"% +8g", complex(negInf, negInf), "(    -Inf    -Infi)"},
+	{"% -8G", complex(NaN, NaN), "( NaN    +NaN    i)"},
+	{"%+-8b", complex(NaN, NaN), "(+NaN    +NaN    i)"},
+	// Zero padding does not apply to infinities and NaN.
+	{"%08f", complex(posInf, posInf), "(    +Inf    +Infi)"},
+	{"%-08g", complex(negInf, negInf), "(-Inf    -Inf    i)"},
+	{"%-08G", complex(NaN, NaN), "(NaN     +NaN    i)"},
 
 	// old test/fmt_test.go
-	{"%d", 1234, "1234"},
-	{"%d", -1234, "-1234"},
-	{"%d", uint(1234), "1234"},
-	{"%d", uint32(b32), "4294967295"},
-	{"%d", uint64(b64), "18446744073709551615"},
-	{"%o", 01234, "1234"},
-	{"%#o", 01234, "01234"},
-	{"%o", uint32(b32), "37777777777"},
-	{"%o", uint64(b64), "1777777777777777777777"},
-	{"%x", 0x1234abcd, "1234abcd"},
-	{"%#x", 0x1234abcd, "0x1234abcd"},
-	{"%x", b32 - 0x1234567, "fedcba98"},
-	{"%X", 0x1234abcd, "1234ABCD"},
-	{"%X", b32 - 0x1234567, "FEDCBA98"},
-	{"%#X", 0, "0X0"},
-	{"%x", b64, "ffffffffffffffff"},
-	{"%b", 7, "111"},
-	{"%b", b64, "1111111111111111111111111111111111111111111111111111111111111111"},
-	{"%b", -6, "-110"},
 	{"%e", 1.0, "1.000000e+00"},
 	{"%e", 1234.5678e3, "1.234568e+06"},
 	{"%e", 1234.5678e-8, "1.234568e-05"},
@@ -345,19 +517,6 @@ var fmtTests = []struct {
 	{"%G", -7.0, "-7"},
 	{"%G", -1e-9, "-1E-09"},
 	{"%G", float32(-1e-9), "-1E-09"},
-	{"%c", 'x', "x"},
-	{"%c", 0xe4, "ä"},
-	{"%c", 0x672c, "本"},
-	{"%c", '日', "日"},
-	{"%20.8d", 1234, "            00001234"},
-	{"%20.8d", -1234, "           -00001234"},
-	{"%20d", 1234, "                1234"},
-	{"%-20.8d", 1234, "00001234            "},
-	{"%-20.8d", -1234, "-00001234           "},
-	{"%-#20.8x", 0x1234abc, "0x01234abc          "},
-	{"%-#20.8X", 0x1234abc, "0X01234ABC          "},
-	{"%-#20.8o", 01234, "00001234            "},
-	{"%.20b", 7, "00000000000000000111"},
 	{"%20.5s", "qwertyuiop", "               qwert"},
 	{"%.5s", "qwertyuiop", "qwert"},
 	{"%-20.5s", "qwertyuiop", "qwert               "},
@@ -377,9 +536,6 @@ var fmtTests = []struct {
 	{"%g", 1.23456789e3, "1234.56789"},
 	{"%g", 1.23456789e-3, "0.00123456789"},
 	{"%g", 1.23456789e20, "1.23456789e+20"},
-	{"%20e", math.Inf(1), "                +Inf"},
-	{"%-20f", math.Inf(-1), "-Inf                "},
-	{"%20g", math.NaN(), "                 NaN"},
 
 	// arrays
 	{"%v", array, "[1 2 3 4 5]"},
@@ -396,13 +552,44 @@ var fmtTests = []struct {
 	{"%v", &slice, "&[1 2 3 4 5]"},
 	{"%v", &islice, "&[1 hello 2.5 <nil>]"},
 	{"%v", &bslice, "&[1 2 3 4 5]"},
-	{"%v", []byte{1}, "[1]"},
-	{"%v", []byte{}, "[]"},
+
+	// byte arrays and slices with %b,%c,%d,%o,%U and %v
+	{"%b", [3]byte{65, 66, 67}, "[1000001 1000010 1000011]"},
+	{"%c", [3]byte{65, 66, 67}, "[A B C]"},
+	{"%d", [3]byte{65, 66, 67}, "[65 66 67]"},
+	{"%o", [3]byte{65, 66, 67}, "[101 102 103]"},
+	{"%U", [3]byte{65, 66, 67}, "[U+0041 U+0042 U+0043]"},
+	{"%v", [3]byte{65, 66, 67}, "[65 66 67]"},
+	{"%v", [1]byte{123}, "[123]"},
+	{"%012v", []byte{}, "[]"},
+	{"%#012v", []byte{}, "[]byte{}"},
+	{"%6v", []byte{1, 11, 111}, "[     1     11    111]"},
+	{"%06v", []byte{1, 11, 111}, "[000001 000011 000111]"},
+	{"%-6v", []byte{1, 11, 111}, "[1      11     111   ]"},
+	{"%-06v", []byte{1, 11, 111}, "[1      11     111   ]"},
+	{"%#v", []byte{1, 11, 111}, "[]byte{0x1, 0xb, 0x6f}"},
+	{"%#6v", []byte{1, 11, 111}, "[]byte{   0x1,    0xb,   0x6f}"},
+	{"%#06v", []byte{1, 11, 111}, "[]byte{0x000001, 0x00000b, 0x00006f}"},
+	{"%#-6v", []byte{1, 11, 111}, "[]byte{0x1   , 0xb   , 0x6f  }"},
+	{"%#-06v", []byte{1, 11, 111}, "[]byte{0x1   , 0xb   , 0x6f  }"},
+	// f.space should and f.plus should not have an effect with %v.
+	{"% v", []byte{1, 11, 111}, "[ 1  11  111]"},
+	{"%+v", [3]byte{1, 11, 111}, "[1 11 111]"},
+	{"%# -6v", []byte{1, 11, 111}, "[]byte{ 0x1  ,  0xb  ,  0x6f }"},
+	{"%#+-6v", [3]byte{1, 11, 111}, "[3]uint8{0x1   , 0xb   , 0x6f  }"},
+	// f.space and f.plus should have an effect with %d.
+	{"% d", []byte{1, 11, 111}, "[ 1  11  111]"},
+	{"%+d", [3]byte{1, 11, 111}, "[+1 +11 +111]"},
+	{"%# -6d", []byte{1, 11, 111}, "[ 1      11     111  ]"},
+	{"%#+-6d", [3]byte{1, 11, 111}, "[+1     +11    +111  ]"},
+
+	// floates with %v
+	{"%v", 1.2345678, "1.2345678"},
+	{"%v", float32(1.2345678), "1.2345678"},
 
 	// complexes with %v
 	{"%v", 1 + 2i, "(1+2i)"},
 	{"%v", complex64(1 + 2i), "(1+2i)"},
-	{"%v", complex128(1 + 2i), "(1+2i)"},
 
 	// structs
 	{"%v", A{1, 2, "a", []int{1, 2}}, `{1 2 a [1 2]}`},
@@ -422,7 +609,7 @@ var fmtTests = []struct {
 
 	// go syntax
 	{"%#v", A{1, 2, "a", []int{1, 2}}, `fmt_test.A{i:1, j:0x2, s:"a", x:[]int{1, 2}}`},
-	{"%#v", &b, "(*uint8)(0xPTR)"},
+	{"%#v", new(byte), "(*uint8)(0xPTR)"},
 	{"%#v", TestFmtInterface, "(func(*testing.T))(0xPTR)"},
 	{"%#v", make(chan int), "(chan int)(0xPTR)"},
 	{"%#v", uint64(1<<64 - 1), "0xffffffffffffffff"},
@@ -442,8 +629,20 @@ var fmtTests = []struct {
 	{"%#v", "foo", `"foo"`},
 	{"%#v", barray, `[5]fmt_test.renamedUint8{0x1, 0x2, 0x3, 0x4, 0x5}`},
 	{"%#v", bslice, `[]fmt_test.renamedUint8{0x1, 0x2, 0x3, 0x4, 0x5}`},
-	{"%#v", []byte(nil), "[]byte(nil)"},
 	{"%#v", []int32(nil), "[]int32(nil)"},
+	{"%#v", 1.2345678, "1.2345678"},
+	{"%#v", float32(1.2345678), "1.2345678"},
+	// Only print []byte and []uint8 as type []byte if they appear at the top level.
+	{"%#v", []byte(nil), "[]byte(nil)"},
+	{"%#v", []uint8(nil), "[]byte(nil)"},
+	{"%#v", []byte{}, "[]byte{}"},
+	{"%#v", []uint8{}, "[]byte{}"},
+	{"%#v", reflect.ValueOf([]byte{}), "[]uint8{}"},
+	{"%#v", reflect.ValueOf([]uint8{}), "[]uint8{}"},
+	{"%#v", &[]byte{}, "&[]uint8{}"},
+	{"%#v", &[]byte{}, "&[]uint8{}"},
+	{"%#v", [3]byte{}, "[3]uint8{0x0, 0x0, 0x0}"},
+	{"%#v", [3]uint8{}, "[3]uint8{0x0, 0x0, 0x0}"},
 
 	// slices with other formats
 	{"%#x", []int{1, 2, 15}, `[0x1 0x2 0xf]`},
@@ -453,30 +652,61 @@ var fmtTests = []struct {
 	{"%q", []string{"a", "b"}, `["a" "b"]`},
 	{"% 02x", []byte{1}, "01"},
 	{"% 02x", []byte{1, 2, 3}, "01 02 03"},
+
 	// Padding with byte slices.
-	{"%x", []byte{}, ""},
-	{"%02x", []byte{}, "00"},
+	{"%2x", []byte{}, "  "},
+	{"%#2x", []byte{}, "  "},
 	{"% 02x", []byte{}, "00"},
-	{"%08x", []byte{0xab}, "000000ab"},
-	{"% 08x", []byte{0xab}, "000000ab"},
-	{"%08x", []byte{0xab, 0xcd}, "0000abcd"},
-	{"% 08x", []byte{0xab, 0xcd}, "000ab cd"},
+	{"%# 02x", []byte{}, "00"},
+	{"%-2x", []byte{}, "  "},
+	{"%-02x", []byte{}, "  "},
 	{"%8x", []byte{0xab}, "      ab"},
 	{"% 8x", []byte{0xab}, "      ab"},
-	{"%8x", []byte{0xab, 0xcd}, "    abcd"},
-	{"% 8x", []byte{0xab, 0xcd}, "   ab cd"},
+	{"%#8x", []byte{0xab}, "    0xab"},
+	{"%# 8x", []byte{0xab}, "    0xab"},
+	{"%08x", []byte{0xab}, "000000ab"},
+	{"% 08x", []byte{0xab}, "000000ab"},
+	{"%#08x", []byte{0xab}, "00000xab"},
+	{"%# 08x", []byte{0xab}, "00000xab"},
+	{"%10x", []byte{0xab, 0xcd}, "      abcd"},
+	{"% 10x", []byte{0xab, 0xcd}, "     ab cd"},
+	{"%#10x", []byte{0xab, 0xcd}, "    0xabcd"},
+	{"%# 10x", []byte{0xab, 0xcd}, " 0xab 0xcd"},
+	{"%010x", []byte{0xab, 0xcd}, "000000abcd"},
+	{"% 010x", []byte{0xab, 0xcd}, "00000ab cd"},
+	{"%#010x", []byte{0xab, 0xcd}, "00000xabcd"},
+	{"%# 010x", []byte{0xab, 0xcd}, "00xab 0xcd"},
+	{"%-10X", []byte{0xab}, "AB        "},
+	{"% -010X", []byte{0xab}, "AB        "},
+	{"%#-10X", []byte{0xab, 0xcd}, "0XABCD    "},
+	{"%# -010X", []byte{0xab, 0xcd}, "0XAB 0XCD "},
 	// Same for strings
-	{"%x", "", ""},
-	{"%02x", "", "00"},
+	{"%2x", "", "  "},
+	{"%#2x", "", "  "},
 	{"% 02x", "", "00"},
-	{"%08x", "\xab", "000000ab"},
-	{"% 08x", "\xab", "000000ab"},
-	{"%08x", "\xab\xcd", "0000abcd"},
-	{"% 08x", "\xab\xcd", "000ab cd"},
+	{"%# 02x", "", "00"},
+	{"%-2x", "", "  "},
+	{"%-02x", "", "  "},
 	{"%8x", "\xab", "      ab"},
 	{"% 8x", "\xab", "      ab"},
-	{"%8x", "\xab\xcd", "    abcd"},
-	{"% 8x", "\xab\xcd", "   ab cd"},
+	{"%#8x", "\xab", "    0xab"},
+	{"%# 8x", "\xab", "    0xab"},
+	{"%08x", "\xab", "000000ab"},
+	{"% 08x", "\xab", "000000ab"},
+	{"%#08x", "\xab", "00000xab"},
+	{"%# 08x", "\xab", "00000xab"},
+	{"%10x", "\xab\xcd", "      abcd"},
+	{"% 10x", "\xab\xcd", "     ab cd"},
+	{"%#10x", "\xab\xcd", "    0xabcd"},
+	{"%# 10x", "\xab\xcd", " 0xab 0xcd"},
+	{"%010x", "\xab\xcd", "000000abcd"},
+	{"% 010x", "\xab\xcd", "00000ab cd"},
+	{"%#010x", "\xab\xcd", "00000xabcd"},
+	{"%# 010x", "\xab\xcd", "00xab 0xcd"},
+	{"%-10X", "\xab", "AB        "},
+	{"% -010X", "\xab", "AB        "},
+	{"%#-10X", "\xab\xcd", "0XABCD    "},
+	{"%# -010X", "\xab\xcd", "0XAB 0XCD "},
 
 	// renamings
 	{"%v", renamedBool(true), "true"},
@@ -495,7 +725,8 @@ var fmtTests = []struct {
 	{"%x", renamedString("thing"), "7468696e67"},
 	{"%d", renamedBytes([]byte{1, 2, 15}), `[1 2 15]`},
 	{"%q", renamedBytes([]byte("hello")), `"hello"`},
-	{"%x", []renamedUint8{'a', 'b', 'c'}, "616263"},
+	{"%x", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, "68656c6c6f"},
+	{"%X", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, "68656C6C6F"},
 	{"%s", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, "hello"},
 	{"%q", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, `"hello"`},
 	{"%v", renamedFloat32(22), "22"},
@@ -513,79 +744,72 @@ var fmtTests = []struct {
 	{"%#v", S{F(7), G(8)}, "fmt_test.S{F:<v=F(7)>, G:GoString(8)}"},
 
 	// %T
+	{"%T", byte(0), "uint8"},
+	{"%T", reflect.ValueOf(nil), "reflect.Value"},
 	{"%T", (4 - 3i), "complex128"},
 	{"%T", renamedComplex128(4 - 3i), "fmt_test.renamedComplex128"},
-	{"%T", intVal, "int"},
-	{"%6T", &intVal, "  *int"},
+	{"%T", intVar, "int"},
+	{"%6T", &intVar, "  *int"},
 	{"%10T", nil, "     <nil>"},
 	{"%-10T", nil, "<nil>     "},
 
-	// %p
-	{"p0=%p", new(int), "p0=0xPTR"},
-	{"p1=%s", &pValue, "p1=String(p)"}, // String method...
-	{"p2=%p", &pValue, "p2=0xPTR"},     // ... not called with %p
-	{"p3=%p", (*int)(nil), "p3=0x0"},
-	{"p4=%#p", new(int), "p4=PTR"},
-
+	// %p with pointers
+	{"%p", (*int)(nil), "0x0"},
+	{"%#p", (*int)(nil), "0"},
+	{"%p", &intVar, "0xPTR"},
+	{"%#p", &intVar, "PTR"},
+	{"%p", &array, "0xPTR"},
+	{"%p", &slice, "0xPTR"},
+	{"%8.2p", (*int)(nil), "    0x00"},
+	{"%-20.16p", &intVar, "0xPTR  "},
 	// %p on non-pointers
 	{"%p", make(chan int), "0xPTR"},
 	{"%p", make(map[int]int), "0xPTR"},
-	{"%p", make([]int, 1), "0xPTR"},
-	{"%p", 27, "%!p(int=27)"}, // not a pointer at all
-
-	// %q on pointers
-	{"%q", (*int)(nil), "%!q(*int=<nil>)"},
-	{"%q", new(int), "%!q(*int=0xPTR)"},
-
-	// %v on pointers formats 0 as <nil>
+	{"%p", func() {}, "0xPTR"},
+	{"%p", 27, "%!p(int=27)"},  // not a pointer at all
+	{"%p", nil, "%!p(<nil>)"},  // nil on its own has no type ...
+	{"%#p", nil, "%!p(<nil>)"}, // ... and hence is not a pointer type.
+	// pointers with specified base
+	{"%b", &intVar, "PTR_b"},
+	{"%d", &intVar, "PTR_d"},
+	{"%o", &intVar, "PTR_o"},
+	{"%x", &intVar, "PTR_x"},
+	{"%X", &intVar, "PTR_X"},
+	// %v on pointers
+	{"%v", nil, "<nil>"},
+	{"%#v", nil, "<nil>"},
 	{"%v", (*int)(nil), "<nil>"},
-	{"%v", new(int), "0xPTR"},
-
-	// %d etc. pointers use specified base.
-	{"%d", new(int), "PTR_d"},
-	{"%o", new(int), "PTR_o"},
-	{"%x", new(int), "PTR_x"},
+	{"%#v", (*int)(nil), "(*int)(nil)"},
+	{"%v", &intVar, "0xPTR"},
+	{"%#v", &intVar, "(*int)(0xPTR)"},
+	{"%8.2v", (*int)(nil), "   <nil>"},
+	{"%-20.16v", &intVar, "0xPTR  "},
+	// string method on pointer
+	{"%s", &pValue, "String(p)"}, // String method...
+	{"%p", &pValue, "0xPTR"},     // ... is not called with %p.
 
 	// %d on Stringer should give integer if possible
 	{"%s", time.Time{}.Month(), "January"},
 	{"%d", time.Time{}.Month(), "1"},
 
 	// erroneous things
+	{"", nil, "%!(EXTRA <nil>)"},
+	{"", 2, "%!(EXTRA int=2)"},
+	{"no args", "hello", "no args%!(EXTRA string=hello)"},
 	{"%s %", "hello", "hello %!(NOVERB)"},
 	{"%s %.2", "hello", "hello %!(NOVERB)"},
-	{"%d", "hello", "%!d(string=hello)"},
-	{"no args", "hello", "no args%!(EXTRA string=hello)"},
-	{"%s", nil, "%!s(<nil>)"},
-	{"%T", nil, "<nil>"},
-	{"%-1", 100, "%!(NOVERB)%!(EXTRA int=100)"},
 	{"%017091901790959340919092959340919017929593813360", 0, "%!(NOVERB)%!(EXTRA int=0)"},
 	{"%184467440737095516170v", 0, "%!(NOVERB)%!(EXTRA int=0)"},
+	// Extra argument errors should format without flags set.
+	{"%010.2", "12345", "%!(NOVERB)%!(EXTRA string=12345)"},
 
 	// The "<nil>" show up because maps are printed by
 	// first obtaining a list of keys and then looking up
-	// each key.  Since NaNs can be map keys but cannot
+	// each key. Since NaNs can be map keys but cannot
 	// be fetched directly, the lookup fails and returns a
 	// zero reflect.Value, which formats as <nil>.
 	// This test is just to check that it shows the two NaNs at all.
-	{"%v", map[float64]int{math.NaN(): 1, math.NaN(): 2}, "map[NaN:<nil> NaN:<nil>]"},
-
-	// Used to crash because nByte didn't allow for a sign.
-	{"%b", int64(-1 << 63), zeroFill("-1", 63, "")},
-
-	// Used to panic.
-	{"%0100d", 1, zeroFill("", 100, "1")},
-	{"%0100d", -1, zeroFill("-", 99, "1")},
-	{"%0.100f", 1.0, zeroFill("1.", 100, "")},
-	{"%0.100f", -1.0, zeroFill("-1.", 100, "")},
-
-	// Used to panic: integer function didn't look at f.prec, f.unicode, f.width or sign.
-	{"%#.80x", 42, "0x0000000000000000000000000000000000000000000000000000000000000000000000000000002a"},
-	{"%.80U", 42, "U+0000000000000000000000000000000000000000000000000000000000000000000000000000002A"},
-	{"%#.80U", '日', "U+000000000000000000000000000000000000000000000000000000000000000000000000000065E5 '日'"},
-	{"%.65d", -44, "-00000000000000000000000000000000000000000000000000000000000000044"},
-	{"%+.65d", 44, "+00000000000000000000000000000000000000000000000000000000000000044"},
-	{"% .65d", 44, " 00000000000000000000000000000000000000000000000000000000000000044"},
-	{"%  +.65d", 44, "+00000000000000000000000000000000000000000000000000000000000000044"},
+	{"%v", map[float64]int{NaN: 1, NaN: 2}, "map[NaN:<nil> NaN:<nil>]"},
 
 	// Comparison of padding rules with C printf.
 	/*
@@ -599,14 +823,16 @@ var fmtTests = []struct {
 			"[%7.2f]",
 			"[% 7.2f]",
 			"[%+7.2f]",
+			"[% +7.2f]",
 			"[%07.2f]",
 			"[% 07.2f]",
 			"[%+07.2f]",
+			"[% +07.2f]"
 		};
 
 		int main(void) {
 			int i;
-			for(i = 0; i < 9; i++) {
+			for(i = 0; i < 11; i++) {
 				printf("%s: ", format[i]);
 				printf(format[i], 1.0);
 				printf(" ");
@@ -622,9 +848,12 @@ var fmtTests = []struct {
 			[%7.2f]: [   1.00] [  -1.00]
 			[% 7.2f]: [   1.00] [  -1.00]
 			[%+7.2f]: [  +1.00] [  -1.00]
+			[% +7.2f]: [  +1.00] [  -1.00]
 			[%07.2f]: [0001.00] [-001.00]
 			[% 07.2f]: [ 001.00] [-001.00]
 			[%+07.2f]: [+001.00] [-001.00]
+			[% +07.2f]: [+001.00] [-001.00]
+
 	*/
 	{"%.2f", 1.0, "1.00"},
 	{"%.2f", -1.0, "-1.00"},
@@ -638,26 +867,35 @@ var fmtTests = []struct {
 	{"% 7.2f", -1.0, "  -1.00"},
 	{"%+7.2f", 1.0, "  +1.00"},
 	{"%+7.2f", -1.0, "  -1.00"},
+	{"% +7.2f", 1.0, "  +1.00"},
+	{"% +7.2f", -1.0, "  -1.00"},
 	{"%07.2f", 1.0, "0001.00"},
 	{"%07.2f", -1.0, "-001.00"},
 	{"% 07.2f", 1.0, " 001.00"},
 	{"% 07.2f", -1.0, "-001.00"},
 	{"%+07.2f", 1.0, "+001.00"},
 	{"%+07.2f", -1.0, "-001.00"},
+	{"% +07.2f", 1.0, "+001.00"},
+	{"% +07.2f", -1.0, "-001.00"},
 
 	// Complex numbers: exhaustively tested in TestComplexFormatting.
 	{"%7.2f", 1 + 2i, "(   1.00  +2.00i)"},
 	{"%+07.2f", -1 - 2i, "(-001.00-002.00i)"},
-	// Zero padding does not apply to infinities.
-	{"%020f", math.Inf(-1), "                -Inf"},
-	{"%020f", math.Inf(+1), "                +Inf"},
-	{"% 020f", math.Inf(-1), "                -Inf"},
-	{"% 020f", math.Inf(+1), "                 Inf"},
-	{"%+020f", math.Inf(-1), "                -Inf"},
-	{"%+020f", math.Inf(+1), "                +Inf"},
-	{"%20f", -1.0, "           -1.000000"},
-	// Make sure we can handle very large widths.
-	{"%0100f", -1.0, zeroFill("-", 99, "1.000000")},
+
+	// Use spaces instead of zero if padding to the right.
+	{"%0-5s", "abc", "abc  "},
+	{"%-05.1f", 1.0, "1.0  "},
+
+	// float and complex formatting should not change the padding width
+	// for other elements. See issue 14642.
+	{"%06v", []interface{}{+10.0, 10}, "[000010 000010]"},
+	{"%06v", []interface{}{-10.0, 10}, "[-00010 000010]"},
+	{"%06v", []interface{}{+10.0 + 10i, 10}, "[(000010+00010i) 000010]"},
+	{"%06v", []interface{}{-10.0 + 10i, 10}, "[(-00010+00010i) 000010]"},
+
+	// integer formatting should not alter padding for other elements.
+	{"%03.6v", []interface{}{1, 2.0, "x"}, "[000001 002 00x]"},
+	{"%03.0v", []interface{}{0, 2.0, "x"}, "[    002 000]"},
 
 	// Complex fmt used to leave the plus flag set for future entries in the array
 	// causing +2+0i and +3+0i instead of 2+0i and 3+0i.
@@ -667,27 +905,6 @@ var fmtTests = []struct {
 	// Incomplete format specification caused crash.
 	{"%.", 3, "%!.(int=3)"},
 
-	// Used to panic with out-of-bounds for very large numeric representations.
-	// nByte is set to handle one bit per uint64 in %b format, with a negative number.
-	// See issue 6777.
-	{"%#064x", 1, zeroFill("0x", 64, "1")},
-	{"%#064x", -1, zeroFill("-0x", 63, "1")},
-	{"%#064b", 1, zeroFill("", 64, "1")},
-	{"%#064b", -1, zeroFill("-", 63, "1")},
-	{"%#064o", 1, zeroFill("", 64, "1")},
-	{"%#064o", -1, zeroFill("-", 63, "1")},
-	{"%#064d", 1, zeroFill("", 64, "1")},
-	{"%#064d", -1, zeroFill("-", 63, "1")},
-	// Test that we handle the crossover above the size of uint64
-	{"%#072x", 1, zeroFill("0x", 72, "1")},
-	{"%#072x", -1, zeroFill("-0x", 71, "1")},
-	{"%#072b", 1, zeroFill("", 72, "1")},
-	{"%#072b", -1, zeroFill("-", 71, "1")},
-	{"%#072o", 1, zeroFill("", 72, "1")},
-	{"%#072o", -1, zeroFill("-", 71, "1")},
-	{"%#072d", 1, zeroFill("", 72, "1")},
-	{"%#072d", -1, zeroFill("-", 71, "1")},
-
 	// Padding for complex numbers. Has been bad, then fixed, then bad again.
 	{"%+10.2f", +104.66 + 440.51i, "(   +104.66   +440.51i)"},
 	{"%+10.2f", -104.66 + 440.51i, "(   -104.66   +440.51i)"},
@@ -699,19 +916,21 @@ var fmtTests = []struct {
 	{"%+010.2f", -104.66 - 440.51i, "(-000104.66-000440.51i)"},
 
 	// []T where type T is a byte with a Stringer method.
-	{"%v", byteStringerSlice, "[X X X X]"},
-	{"%s", byteStringerSlice, "abcd"},
-	{"%q", byteStringerSlice, "\"abcd\""},
-	{"%x", byteStringerSlice, "61626364"},
-	{"%#v", byteStringerSlice, "[]fmt_test.byteStringer{0x61, 0x62, 0x63, 0x64}"},
+	{"%v", byteStringerSlice, "[X X X X X]"},
+	{"%s", byteStringerSlice, "hello"},
+	{"%q", byteStringerSlice, "\"hello\""},
+	{"%x", byteStringerSlice, "68656c6c6f"},
+	{"%X", byteStringerSlice, "68656C6C6F"},
+	{"%#v", byteStringerSlice, "[]fmt_test.byteStringer{0x68, 0x65, 0x6c, 0x6c, 0x6f}"},
 
 	// And the same for Formatter.
-	{"%v", byteFormatterSlice, "[X X X X]"},
-	{"%s", byteFormatterSlice, "abcd"},
-	{"%q", byteFormatterSlice, "\"abcd\""},
-	{"%x", byteFormatterSlice, "61626364"},
+	{"%v", byteFormatterSlice, "[X X X X X]"},
+	{"%s", byteFormatterSlice, "hello"},
+	{"%q", byteFormatterSlice, "\"hello\""},
+	{"%x", byteFormatterSlice, "68656c6c6f"},
+	{"%X", byteFormatterSlice, "68656C6C6F"},
 	// This next case seems wrong, but the docs say the Formatter wins here.
-	{"%#v", byteFormatterSlice, "[]fmt_test.byteFormatter{X, X, X, X}"},
+	{"%#v", byteFormatterSlice, "[]fmt_test.byteFormatter{X, X, X, X, X}"},
 
 	// reflect.Value handled specially in Go 1.5, making it possible to
 	// see inside non-exported fields (which cannot be accessed with Interface()).
@@ -726,6 +945,32 @@ var fmtTests = []struct {
 
 	// invalid reflect.Value doesn't crash.
 	{"%v", reflect.Value{}, "<invalid reflect.Value>"},
+	{"%v", &reflect.Value{}, "<invalid Value>"},
+	{"%v", SI{reflect.Value{}}, "{<invalid Value>}"},
+
+	// Tests to check that not supported verbs generate an error string.
+	{"%☠", nil, "%!☠(<nil>)"},
+	{"%☠", interface{}(nil), "%!☠(<nil>)"},
+	{"%☠", int(0), "%!☠(int=0)"},
+	{"%☠", uint(0), "%!☠(uint=0)"},
+	{"%☠", []byte{0, 1}, "[%!☠(uint8=0) %!☠(uint8=1)]"},
+	{"%☠", []uint8{0, 1}, "[%!☠(uint8=0) %!☠(uint8=1)]"},
+	{"%☠", [1]byte{0}, "[%!☠(uint8=0)]"},
+	{"%☠", [1]uint8{0}, "[%!☠(uint8=0)]"},
+	{"%☠", "hello", "%!☠(string=hello)"},
+	{"%☠", 1.2345678, "%!☠(float64=1.2345678)"},
+	{"%☠", float32(1.2345678), "%!☠(float32=1.2345678)"},
+	{"%☠", 1.2345678 + 1.2345678i, "%!☠(complex128=(1.2345678+1.2345678i))"},
+	{"%☠", complex64(1.2345678 + 1.2345678i), "%!☠(complex64=(1.2345678+1.2345678i))"},
+	{"%☠", &intVar, "%!☠(*int=0xPTR)"},
+	{"%☠", make(chan int), "%!☠(chan int=0xPTR)"},
+	{"%☠", func() {}, "%!☠(func()=0xPTR)"},
+	{"%☠", reflect.ValueOf(renamedInt(0)), "%!☠(fmt_test.renamedInt=0)"},
+	{"%☠", SI{renamedInt(0)}, "{%!☠(fmt_test.renamedInt=0)}"},
+	{"%☠", &[]interface{}{I(1), G(2)}, "&[%!☠(fmt_test.I=1) %!☠(fmt_test.G=2)]"},
+	{"%☠", SI{&[]interface{}{I(1), G(2)}}, "{%!☠(*[]interface {}=&[1 2])}"},
+	{"%☠", reflect.Value{}, "<invalid reflect.Value>"},
+	{"%☠", map[float64]int{NaN: 1}, "map[%!☠(float64=NaN):%!☠(<nil>)]"},
 }
 
 // zeroFill generates zero-filled strings of the specified width. The length
@@ -737,27 +982,37 @@ func zeroFill(prefix string, width int, suffix string) string {
 func TestSprintf(t *testing.T) {
 	for _, tt := range fmtTests {
 		s := Sprintf(tt.fmt, tt.val)
-		if i := strings.Index(tt.out, "PTR"); i >= 0 {
-			pattern := "PTR"
-			chars := "0123456789abcdefABCDEF"
+		i := strings.Index(tt.out, "PTR")
+		if i >= 0 && i < len(s) {
+			var pattern, chars string
 			switch {
-			case strings.HasPrefix(tt.out[i:], "PTR_d"):
-				pattern = "PTR_d"
-				chars = chars[:10]
+			case strings.HasPrefix(tt.out[i:], "PTR_b"):
+				pattern = "PTR_b"
+				chars = "01"
 			case strings.HasPrefix(tt.out[i:], "PTR_o"):
 				pattern = "PTR_o"
-				chars = chars[:8]
+				chars = "01234567"
+			case strings.HasPrefix(tt.out[i:], "PTR_d"):
+				pattern = "PTR_d"
+				chars = "0123456789"
 			case strings.HasPrefix(tt.out[i:], "PTR_x"):
 				pattern = "PTR_x"
+				chars = "0123456789abcdef"
+			case strings.HasPrefix(tt.out[i:], "PTR_X"):
+				pattern = "PTR_X"
+				chars = "0123456789ABCDEF"
+			default:
+				pattern = "PTR"
+				chars = "0123456789abcdefABCDEF"
 			}
-			j := i
-			for ; j < len(s); j++ {
-				c := s[j]
-				if !strings.ContainsRune(chars, rune(c)) {
+			p := s[:i] + pattern
+			for j := i; j < len(s); j++ {
+				if !strings.ContainsRune(chars, rune(s[j])) {
+					p += s[j:]
 					break
 				}
 			}
-			s = s[0:i] + pattern + s[j:]
+			s = p
 		}
 		if s != tt.out {
 			if _, ok := tt.val.(string); ok {
@@ -775,7 +1030,7 @@ func TestSprintf(t *testing.T) {
 // thing as if done by hand with two singleton prints.
 func TestComplexFormatting(t *testing.T) {
 	var yesNo = []bool{true, false}
-	var values = []float64{1, 0, -1, math.Inf(1), math.Inf(-1), math.NaN()}
+	var values = []float64{1, 0, -1, posInf, negInf, NaN}
 	for _, plus := range yesNo {
 		for _, zero := range yesNo {
 			for _, space := range yesNo {
@@ -869,6 +1124,14 @@ func TestReorder(t *testing.T) {
 	}
 }
 
+func BenchmarkSprintfPadding(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%16f", 1.0)
+		}
+	})
+}
+
 func BenchmarkSprintfEmpty(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -885,6 +1148,22 @@ func BenchmarkSprintfString(b *testing.B) {
 	})
 }
 
+func BenchmarkSprintfTruncateString(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%.3s", "日本語日本語日本語")
+		}
+	})
+}
+
+func BenchmarkSprintfQuoteString(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%q", "日本語日本語日本語")
+		}
+	})
+}
+
 func BenchmarkSprintfInt(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -917,6 +1196,66 @@ func BenchmarkSprintfFloat(b *testing.B) {
 	})
 }
 
+func BenchmarkSprintfComplex(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%f", 5.23184+5.23184i)
+		}
+	})
+}
+
+func BenchmarkSprintfBoolean(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%t", true)
+		}
+	})
+}
+
+func BenchmarkSprintfHexString(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("% #x", "0123456789abcdef")
+		}
+	})
+}
+
+func BenchmarkSprintfHexBytes(b *testing.B) {
+	data := []byte("0123456789abcdef")
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("% #x", data)
+		}
+	})
+}
+
+func BenchmarkSprintfBytes(b *testing.B) {
+	data := []byte("0123456789abcdef")
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%v", data)
+		}
+	})
+}
+
+func BenchmarkSprintfStringer(b *testing.B) {
+	stringer := I(12345)
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%v", stringer)
+		}
+	})
+}
+
+func BenchmarkSprintfStructure(b *testing.B) {
+	s := &[]interface{}{SI{12345}, map[int]string{0: "hello"}}
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			Sprintf("%#v", s)
+		}
+	})
+}
+
 func BenchmarkManyArgs(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		var buf bytes.Buffer
diff --git a/libgo/go/fmt/format.go b/libgo/go/fmt/format.go
index 517b18f7d43..023647501a0 100644
--- a/libgo/go/fmt/format.go
+++ b/libgo/go/fmt/format.go
@@ -5,18 +5,13 @@
 package fmt
 
 import (
-	"math"
 	"strconv"
 	"unicode/utf8"
 )
 
 const (
-	// %b of an int64, plus a sign.
-	// Hex can add 0x and we handle it specially.
-	nByte = 65
-
-	ldigits = "0123456789abcdef"
-	udigits = "0123456789ABCDEF"
+	ldigits = "0123456789abcdefx"
+	udigits = "0123456789ABCDEFX"
 )
 
 const (
@@ -24,16 +19,6 @@ const (
 	unsigned = false
 )
 
-var padZeroBytes = make([]byte, nByte)
-var padSpaceBytes = make([]byte, nByte)
-
-func init() {
-	for i := 0; i < nByte; i++ {
-		padZeroBytes[i] = '0'
-		padSpaceBytes[i] = ' '
-	}
-}
-
 // flags placed in a separate struct for easy clearing.
 type fmtFlags struct {
 	widPresent  bool
@@ -42,8 +27,6 @@ type fmtFlags struct {
 	plus        bool
 	sharp       bool
 	space       bool
-	unicode     bool
-	uniQuote    bool // Use 'x'= prefix for %U if printable.
 	zero        bool
 
 	// For the formats %+v %#v, we set the plusV/sharpV flags
@@ -56,12 +39,16 @@ type fmtFlags struct {
 // A fmt is the raw formatter used by Printf etc.
 // It prints into a buffer that must be set up separately.
 type fmt struct {
-	intbuf [nByte]byte
-	buf    *buffer
-	// width, precision
-	wid  int
-	prec int
+	buf *buffer
+
 	fmtFlags
+
+	wid  int // width
+	prec int // precision
+
+	// intbuf is large enought to store %b of an int64 with a sign and
+	// avoids padding at the end of the struct on 32 bit architectures.
+	intbuf [68]byte
 }
 
 func (f *fmt) clearflags() {
@@ -73,176 +60,213 @@ func (f *fmt) init(buf *buffer) {
 	f.clearflags()
 }
 
-// computePadding computes left and right padding widths (only one will be non-zero).
-func (f *fmt) computePadding(width int) (padding []byte, leftWidth, rightWidth int) {
-	left := !f.minus
-	w := f.wid
-	if w < 0 {
-		left = false
-		w = -w
-	}
-	w -= width
-	if w > 0 {
-		if left && f.zero {
-			return padZeroBytes, w, 0
-		}
-		if left {
-			return padSpaceBytes, w, 0
-		} else {
-			// can't be zero padding on the right
-			return padSpaceBytes, 0, w
-		}
-	}
-	return
-}
-
 // writePadding generates n bytes of padding.
-func (f *fmt) writePadding(n int, padding []byte) {
-	for n > 0 {
-		m := n
-		if m > nByte {
-			m = nByte
-		}
-		f.buf.Write(padding[0:m])
-		n -= m
+func (f *fmt) writePadding(n int) {
+	if n <= 0 { // No padding bytes needed.
+		return
 	}
+	buf := *f.buf
+	oldLen := len(buf)
+	newLen := oldLen + n
+	// Make enough room for padding.
+	if newLen > cap(buf) {
+		buf = make(buffer, cap(buf)*2+n)
+		copy(buf, *f.buf)
+	}
+	// Decide which byte the padding should be filled with.
+	padByte := byte(' ')
+	if f.zero {
+		padByte = byte('0')
+	}
+	// Fill padding with padByte.
+	padding := buf[oldLen:newLen]
+	for i := range padding {
+		padding[i] = padByte
+	}
+	*f.buf = buf[:newLen]
 }
 
-// pad appends b to f.buf, padded on left (w > 0) or right (w < 0 or f.minus).
+// pad appends b to f.buf, padded on left (!f.minus) or right (f.minus).
 func (f *fmt) pad(b []byte) {
 	if !f.widPresent || f.wid == 0 {
 		f.buf.Write(b)
 		return
 	}
-	padding, left, right := f.computePadding(utf8.RuneCount(b))
-	if left > 0 {
-		f.writePadding(left, padding)
-	}
-	f.buf.Write(b)
-	if right > 0 {
-		f.writePadding(right, padding)
+	width := f.wid - utf8.RuneCount(b)
+	if !f.minus {
+		// left padding
+		f.writePadding(width)
+		f.buf.Write(b)
+	} else {
+		// right padding
+		f.buf.Write(b)
+		f.writePadding(width)
 	}
 }
 
-// padString appends s to buf, padded on left (w > 0) or right (w < 0 or f.minus).
+// padString appends s to f.buf, padded on left (!f.minus) or right (f.minus).
 func (f *fmt) padString(s string) {
 	if !f.widPresent || f.wid == 0 {
 		f.buf.WriteString(s)
 		return
 	}
-	padding, left, right := f.computePadding(utf8.RuneCountInString(s))
-	if left > 0 {
-		f.writePadding(left, padding)
-	}
-	f.buf.WriteString(s)
-	if right > 0 {
-		f.writePadding(right, padding)
+	width := f.wid - utf8.RuneCountInString(s)
+	if !f.minus {
+		// left padding
+		f.writePadding(width)
+		f.buf.WriteString(s)
+	} else {
+		// right padding
+		f.buf.WriteString(s)
+		f.writePadding(width)
 	}
 }
 
-var (
-	trueBytes  = []byte("true")
-	falseBytes = []byte("false")
-)
-
 // fmt_boolean formats a boolean.
 func (f *fmt) fmt_boolean(v bool) {
 	if v {
-		f.pad(trueBytes)
+		f.padString("true")
 	} else {
-		f.pad(falseBytes)
+		f.padString("false")
 	}
 }
 
-// integer; interprets prec but not wid.  Once formatted, result is sent to pad()
-// and then flags are cleared.
-func (f *fmt) integer(a int64, base uint64, signedness bool, digits string) {
-	// precision of 0 and value of 0 means "print nothing"
-	if f.precPresent && f.prec == 0 && a == 0 {
-		return
+// fmt_unicode formats a uint64 as "U+0078" or with f.sharp set as "U+0078 'x'".
+func (f *fmt) fmt_unicode(u uint64) {
+	buf := f.intbuf[0:]
+
+	// With default precision set the maximum needed buf length is 18
+	// for formatting -1 with %#U ("U+FFFFFFFFFFFFFFFF") which fits
+	// into the already allocated intbuf with a capacity of 68 bytes.
+	prec := 4
+	if f.precPresent && f.prec > 4 {
+		prec = f.prec
+		// Compute space needed for "U+" , number, " '", character, "'".
+		width := 2 + prec + 2 + utf8.UTFMax + 1
+		if width > len(buf) {
+			buf = make([]byte, width)
+		}
 	}
 
-	negative := signedness == signed && a < 0
+	// Format into buf, ending at buf[i]. Formatting numbers is easier right-to-left.
+	i := len(buf)
+
+	// For %#U we want to add a space and a quoted character at the end of the buffer.
+	if f.sharp && u <= utf8.MaxRune && strconv.IsPrint(rune(u)) {
+		i--
+		buf[i] = '\''
+		i -= utf8.RuneLen(rune(u))
+		utf8.EncodeRune(buf[i:], rune(u))
+		i--
+		buf[i] = '\''
+		i--
+		buf[i] = ' '
+	}
+	// Format the Unicode code point u as a hexadecimal number.
+	for u >= 16 {
+		i--
+		buf[i] = udigits[u&0xF]
+		prec--
+		u >>= 4
+	}
+	i--
+	buf[i] = udigits[u]
+	prec--
+	// Add zeros in front of the number until requested precision is reached.
+	for prec > 0 {
+		i--
+		buf[i] = '0'
+		prec--
+	}
+	// Add a leading "U+".
+	i--
+	buf[i] = '+'
+	i--
+	buf[i] = 'U'
+
+	oldZero := f.zero
+	f.zero = false
+	f.pad(buf[i:])
+	f.zero = oldZero
+}
+
+// fmt_integer formats signed and unsigned integers.
+func (f *fmt) fmt_integer(u uint64, base int, isSigned bool, digits string) {
+	negative := isSigned && int64(u) < 0
 	if negative {
-		a = -a
+		u = -u
 	}
 
-	var buf []byte = f.intbuf[0:]
-	if f.widPresent || f.precPresent || f.plus || f.space {
-		width := f.wid + f.prec // Only one will be set, both are positive; this provides the maximum.
-		if base == 16 && f.sharp {
-			// Also adds "0x".
-			width += 2
-		}
-		if f.unicode {
-			// Also adds "U+".
-			width += 2
-			if f.uniQuote {
-				// Also adds " 'x'".
-				width += 1 + 1 + utf8.UTFMax + 1
-			}
-		}
-		if negative || f.plus || f.space {
-			width++
-		}
-		if width > nByte {
+	buf := f.intbuf[0:]
+	// The already allocated f.intbuf with a capacity of 68 bytes
+	// is large enough for integer formatting when no precision or width is set.
+	if f.widPresent || f.precPresent {
+		// Account 3 extra bytes for possible addition of a sign and "0x".
+		width := 3 + f.wid + f.prec // wid and prec are always positive.
+		if width > len(buf) {
 			// We're going to need a bigger boat.
 			buf = make([]byte, width)
 		}
 	}
 
-	// two ways to ask for extra leading zero digits: %.3d or %03d.
-	// apparently the first cancels the second.
+	// Two ways to ask for extra leading zero digits: %.3d or %03d.
+	// If both are specified the f.zero flag is ignored and
+	// padding with spaces is used instead.
 	prec := 0
 	if f.precPresent {
 		prec = f.prec
-		f.zero = false
-	} else if f.zero && f.widPresent && !f.minus && f.wid > 0 {
+		// Precision of 0 and value of 0 means "print nothing" but padding.
+		if prec == 0 && u == 0 {
+			oldZero := f.zero
+			f.zero = false
+			f.writePadding(f.wid)
+			f.zero = oldZero
+			return
+		}
+	} else if f.zero && f.widPresent {
 		prec = f.wid
 		if negative || f.plus || f.space {
 			prec-- // leave room for sign
 		}
 	}
 
-	// format a into buf, ending at buf[i].  (printing is easier right-to-left.)
-	// a is made into unsigned ua.  we could make things
-	// marginally faster by splitting the 32-bit case out into a separate
-	// block but it's not worth the duplication, so ua has 64 bits.
+	// Because printing is easier right-to-left: format u into buf, ending at buf[i].
+	// We could make things marginally faster by splitting the 32-bit case out
+	// into a separate block but it's not worth the duplication, so u has 64 bits.
 	i := len(buf)
-	ua := uint64(a)
-	// use constants for the division and modulo for more efficient code.
-	// switch cases ordered by popularity.
+	// Use constants for the division and modulo for more efficient code.
+	// Switch cases ordered by popularity.
 	switch base {
 	case 10:
-		for ua >= 10 {
+		for u >= 10 {
 			i--
-			next := ua / 10
-			buf[i] = byte('0' + ua - next*10)
-			ua = next
+			next := u / 10
+			buf[i] = byte('0' + u - next*10)
+			u = next
 		}
 	case 16:
-		for ua >= 16 {
+		for u >= 16 {
 			i--
-			buf[i] = digits[ua&0xF]
-			ua >>= 4
+			buf[i] = digits[u&0xF]
+			u >>= 4
 		}
 	case 8:
-		for ua >= 8 {
+		for u >= 8 {
 			i--
-			buf[i] = byte('0' + ua&7)
-			ua >>= 3
+			buf[i] = byte('0' + u&7)
+			u >>= 3
 		}
 	case 2:
-		for ua >= 2 {
+		for u >= 2 {
 			i--
-			buf[i] = byte('0' + ua&1)
-			ua >>= 1
+			buf[i] = byte('0' + u&1)
+			u >>= 1
 		}
 	default:
 		panic("fmt: unknown base; can't happen")
 	}
 	i--
-	buf[i] = digits[ua]
+	buf[i] = digits[u]
 	for i > 0 && prec > len(buf)-i {
 		i--
 		buf[i] = '0'
@@ -257,18 +281,13 @@ func (f *fmt) integer(a int64, base uint64, signedness bool, digits string) {
 				buf[i] = '0'
 			}
 		case 16:
+			// Add a leading 0x or 0X.
 			i--
-			buf[i] = 'x' + digits[10] - 'a'
+			buf[i] = digits[16]
 			i--
 			buf[i] = '0'
 		}
 	}
-	if f.unicode {
-		i--
-		buf[i] = '+'
-		i--
-		buf[i] = 'U'
-	}
 
 	if negative {
 		i--
@@ -281,36 +300,23 @@ func (f *fmt) integer(a int64, base uint64, signedness bool, digits string) {
 		buf[i] = ' '
 	}
 
-	// If we want a quoted char for %#U, move the data up to make room.
-	if f.unicode && f.uniQuote && a >= 0 && a <= utf8.MaxRune && strconv.IsPrint(rune(a)) {
-		runeWidth := utf8.RuneLen(rune(a))
-		width := 1 + 1 + runeWidth + 1 // space, quote, rune, quote
-		copy(buf[i-width:], buf[i:])   // guaranteed to have enough room.
-		i -= width
-		// Now put " 'x'" at the end.
-		j := len(buf) - width
-		buf[j] = ' '
-		j++
-		buf[j] = '\''
-		j++
-		utf8.EncodeRune(buf[j:], rune(a))
-		j += runeWidth
-		buf[j] = '\''
-	}
-
+	// Left padding with zeros has already been handled like precision earlier
+	// or the f.zero flag is ignored due to an explicitly set precision.
+	oldZero := f.zero
+	f.zero = false
 	f.pad(buf[i:])
+	f.zero = oldZero
 }
 
 // truncate truncates the string to the specified precision, if present.
 func (f *fmt) truncate(s string) string {
-	if f.precPresent && f.prec < utf8.RuneCountInString(s) {
+	if f.precPresent {
 		n := f.prec
 		for i := range s {
-			if n == 0 {
-				s = s[:i]
-				break
-			}
 			n--
+			if n < 0 {
+				return s[:i]
+			}
 		}
 	}
 	return s
@@ -324,212 +330,169 @@ func (f *fmt) fmt_s(s string) {
 
 // fmt_sbx formats a string or byte slice as a hexadecimal encoding of its bytes.
 func (f *fmt) fmt_sbx(s string, b []byte, digits string) {
-	n := len(b)
+	length := len(b)
 	if b == nil {
-		n = len(s)
+		// No byte slice present. Assume string s should be encoded.
+		length = len(s)
+	}
+	// Set length to not process more bytes than the precision demands.
+	if f.precPresent && f.prec < length {
+		length = f.prec
+	}
+	// Compute width of the encoding taking into account the f.sharp and f.space flag.
+	width := 2 * length
+	if width > 0 {
+		if f.space {
+			// Each element encoded by two hexadecimals will get a leading 0x or 0X.
+			if f.sharp {
+				width *= 2
+			}
+			// Elements will be separated by a space.
+			width += length - 1
+		} else if f.sharp {
+			// Only a leading 0x or 0X will be added for the whole string.
+			width += 2
+		}
+	} else { // The byte slice or string that should be encoded is empty.
+		if f.widPresent {
+			f.writePadding(f.wid)
+		}
+		return
+	}
+	// Handle padding to the left.
+	if f.widPresent && f.wid > width && !f.minus {
+		f.writePadding(f.wid - width)
 	}
-	x := digits[10] - 'a' + 'x'
-	// TODO: Avoid buffer by pre-padding.
-	var buf []byte
-	for i := 0; i < n; i++ {
-		if i > 0 && f.space {
+	// Write the encoding directly into the output buffer.
+	buf := *f.buf
+	if f.sharp {
+		// Add leading 0x or 0X.
+		buf = append(buf, '0', digits[16])
+	}
+	var c byte
+	for i := 0; i < length; i++ {
+		if f.space && i > 0 {
+			// Separate elements with a space.
 			buf = append(buf, ' ')
+			if f.sharp {
+				// Add leading 0x or 0X for each element.
+				buf = append(buf, '0', digits[16])
+			}
 		}
-		if f.sharp && (f.space || i == 0) {
-			buf = append(buf, '0', x)
-		}
-		var c byte
-		if b == nil {
-			c = s[i]
+		if b != nil {
+			c = b[i] // Take a byte from the input byte slice.
 		} else {
-			c = b[i]
+			c = s[i] // Take a byte from the input string.
 		}
+		// Encode each byte as two hexadecimal digits.
 		buf = append(buf, digits[c>>4], digits[c&0xF])
 	}
-	f.pad(buf)
+	*f.buf = buf
+	// Handle padding to the right.
+	if f.widPresent && f.wid > width && f.minus {
+		f.writePadding(f.wid - width)
+	}
 }
 
 // fmt_sx formats a string as a hexadecimal encoding of its bytes.
 func (f *fmt) fmt_sx(s, digits string) {
-	if f.precPresent && f.prec < len(s) {
-		s = s[:f.prec]
-	}
 	f.fmt_sbx(s, nil, digits)
 }
 
 // fmt_bx formats a byte slice as a hexadecimal encoding of its bytes.
 func (f *fmt) fmt_bx(b []byte, digits string) {
-	if f.precPresent && f.prec < len(b) {
-		b = b[:f.prec]
-	}
 	f.fmt_sbx("", b, digits)
 }
 
 // fmt_q formats a string as a double-quoted, escaped Go string constant.
+// If f.sharp is set a raw (backquoted) string may be returned instead
+// if the string does not contain any control characters other than tab.
 func (f *fmt) fmt_q(s string) {
 	s = f.truncate(s)
-	var quoted string
 	if f.sharp && strconv.CanBackquote(s) {
-		quoted = "`" + s + "`"
+		f.padString("`" + s + "`")
+		return
+	}
+	buf := f.intbuf[:0]
+	if f.plus {
+		f.pad(strconv.AppendQuoteToASCII(buf, s))
 	} else {
-		if f.plus {
-			quoted = strconv.QuoteToASCII(s)
-		} else {
-			quoted = strconv.Quote(s)
-		}
+		f.pad(strconv.AppendQuote(buf, s))
 	}
-	f.padString(quoted)
 }
 
-// fmt_qc formats the integer as a single-quoted, escaped Go character constant.
+// fmt_c formats an integer as a Unicode character.
 // If the character is not valid Unicode, it will print '\ufffd'.
-func (f *fmt) fmt_qc(c int64) {
-	var quoted []byte
+func (f *fmt) fmt_c(c uint64) {
+	r := rune(c)
+	if c > utf8.MaxRune {
+		r = utf8.RuneError
+	}
+	buf := f.intbuf[:0]
+	w := utf8.EncodeRune(buf[:utf8.UTFMax], r)
+	f.pad(buf[:w])
+}
+
+// fmt_qc formats an integer as a single-quoted, escaped Go character constant.
+// If the character is not valid Unicode, it will print '\ufffd'.
+func (f *fmt) fmt_qc(c uint64) {
+	r := rune(c)
+	if c > utf8.MaxRune {
+		r = utf8.RuneError
+	}
+	buf := f.intbuf[:0]
 	if f.plus {
-		quoted = strconv.AppendQuoteRuneToASCII(f.intbuf[0:0], rune(c))
+		f.pad(strconv.AppendQuoteRuneToASCII(buf, r))
 	} else {
-		quoted = strconv.AppendQuoteRune(f.intbuf[0:0], rune(c))
+		f.pad(strconv.AppendQuoteRune(buf, r))
 	}
-	f.pad(quoted)
 }
 
-// floating-point
-
-func doPrec(f *fmt, def int) int {
+// fmt_float formats a float64. It assumes that verb is a valid format specifier
+// for strconv.AppendFloat and therefore fits into a byte.
+func (f *fmt) fmt_float(v float64, size int, verb rune, prec int) {
+	// Explicit precision in format specifier overrules default precision.
 	if f.precPresent {
-		return f.prec
+		prec = f.prec
 	}
-	return def
-}
-
-// formatFloat formats a float64; it is an efficient equivalent to  f.pad(strconv.FormatFloat()...).
-func (f *fmt) formatFloat(v float64, verb byte, prec, n int) {
 	// Format number, reserving space for leading + sign if needed.
-	num := strconv.AppendFloat(f.intbuf[0:1], v, verb, prec, n)
+	num := strconv.AppendFloat(f.intbuf[:1], v, byte(verb), prec, size)
 	if num[1] == '-' || num[1] == '+' {
 		num = num[1:]
 	} else {
 		num[0] = '+'
 	}
-	// Special handling for infinity, which doesn't look like a number so shouldn't be padded with zeros.
-	if math.IsInf(v, 0) {
-		if f.zero {
-			defer func() { f.zero = true }()
-			f.zero = false
-		}
+	// f.space means to add a leading space instead of a "+" sign unless
+	// the sign is explicitly asked for by f.plus.
+	if f.space && num[0] == '+' && !f.plus {
+		num[0] = ' '
 	}
-	// num is now a signed version of the number.
-	// If we're zero padding, want the sign before the leading zeros.
-	// Achieve this by writing the sign out and then padding the unsigned number.
-	if f.zero && f.widPresent && f.wid > len(num) {
-		if f.space && v >= 0 {
-			f.buf.WriteByte(' ') // This is what C does: even with zero, f.space means space.
-			f.wid--
-		} else if f.plus || v < 0 {
-			f.buf.WriteByte(num[0])
-			f.wid--
+	// Special handling for infinities and NaN,
+	// which don't look like a number so shouldn't be padded with zeros.
+	if num[1] == 'I' || num[1] == 'N' {
+		oldZero := f.zero
+		f.zero = false
+		// Remove sign before NaN if not asked for.
+		if num[1] == 'N' && !f.space && !f.plus {
+			num = num[1:]
 		}
-		f.pad(num[1:])
-		return
-	}
-	// f.space says to replace a leading + with a space.
-	if f.space && num[0] == '+' {
-		num[0] = ' '
 		f.pad(num)
+		f.zero = oldZero
 		return
 	}
-	// Now we know the sign is attached directly to the number, if present at all.
-	// We want a sign if asked for, if it's negative, or if it's infinity (+Inf vs. -Inf).
-	if f.plus || num[0] == '-' || math.IsInf(v, 0) {
+	// We want a sign if asked for and if the sign is not positive.
+	if f.plus || num[0] != '+' {
+		// If we're zero padding to the left we want the sign before the leading zeros.
+		// Achieve this by writing the sign out and then padding the unsigned number.
+		if f.zero && f.widPresent && f.wid > len(num) {
+			f.buf.WriteByte(num[0])
+			f.writePadding(f.wid - len(num))
+			f.buf.Write(num[1:])
+			return
+		}
 		f.pad(num)
 		return
 	}
 	// No sign to show and the number is positive; just print the unsigned number.
 	f.pad(num[1:])
 }
-
-// fmt_e64 formats a float64 in the form -1.23e+12.
-func (f *fmt) fmt_e64(v float64) { f.formatFloat(v, 'e', doPrec(f, 6), 64) }
-
-// fmt_E64 formats a float64 in the form -1.23E+12.
-func (f *fmt) fmt_E64(v float64) { f.formatFloat(v, 'E', doPrec(f, 6), 64) }
-
-// fmt_f64 formats a float64 in the form -1.23.
-func (f *fmt) fmt_f64(v float64) { f.formatFloat(v, 'f', doPrec(f, 6), 64) }
-
-// fmt_g64 formats a float64 in the 'f' or 'e' form according to size.
-func (f *fmt) fmt_g64(v float64) { f.formatFloat(v, 'g', doPrec(f, -1), 64) }
-
-// fmt_G64 formats a float64 in the 'f' or 'E' form according to size.
-func (f *fmt) fmt_G64(v float64) { f.formatFloat(v, 'G', doPrec(f, -1), 64) }
-
-// fmt_fb64 formats a float64 in the form -123p3 (exponent is power of 2).
-func (f *fmt) fmt_fb64(v float64) { f.formatFloat(v, 'b', 0, 64) }
-
-// float32
-// cannot defer to float64 versions
-// because it will get rounding wrong in corner cases.
-
-// fmt_e32 formats a float32 in the form -1.23e+12.
-func (f *fmt) fmt_e32(v float32) { f.formatFloat(float64(v), 'e', doPrec(f, 6), 32) }
-
-// fmt_E32 formats a float32 in the form -1.23E+12.
-func (f *fmt) fmt_E32(v float32) { f.formatFloat(float64(v), 'E', doPrec(f, 6), 32) }
-
-// fmt_f32 formats a float32 in the form -1.23.
-func (f *fmt) fmt_f32(v float32) { f.formatFloat(float64(v), 'f', doPrec(f, 6), 32) }
-
-// fmt_g32 formats a float32 in the 'f' or 'e' form according to size.
-func (f *fmt) fmt_g32(v float32) { f.formatFloat(float64(v), 'g', doPrec(f, -1), 32) }
-
-// fmt_G32 formats a float32 in the 'f' or 'E' form according to size.
-func (f *fmt) fmt_G32(v float32) { f.formatFloat(float64(v), 'G', doPrec(f, -1), 32) }
-
-// fmt_fb32 formats a float32 in the form -123p3 (exponent is power of 2).
-func (f *fmt) fmt_fb32(v float32) { f.formatFloat(float64(v), 'b', 0, 32) }
-
-// fmt_c64 formats a complex64 according to the verb.
-func (f *fmt) fmt_c64(v complex64, verb rune) {
-	f.fmt_complex(float64(real(v)), float64(imag(v)), 32, verb)
-}
-
-// fmt_c128 formats a complex128 according to the verb.
-func (f *fmt) fmt_c128(v complex128, verb rune) {
-	f.fmt_complex(real(v), imag(v), 64, verb)
-}
-
-// fmt_complex formats a complex number as (r+ji).
-func (f *fmt) fmt_complex(r, j float64, size int, verb rune) {
-	f.buf.WriteByte('(')
-	oldPlus := f.plus
-	oldSpace := f.space
-	oldWid := f.wid
-	for i := 0; ; i++ {
-		switch verb {
-		case 'b':
-			f.formatFloat(r, 'b', 0, size)
-		case 'e':
-			f.formatFloat(r, 'e', doPrec(f, 6), size)
-		case 'E':
-			f.formatFloat(r, 'E', doPrec(f, 6), size)
-		case 'f', 'F':
-			f.formatFloat(r, 'f', doPrec(f, 6), size)
-		case 'g':
-			f.formatFloat(r, 'g', doPrec(f, -1), size)
-		case 'G':
-			f.formatFloat(r, 'G', doPrec(f, -1), size)
-		}
-		if i != 0 {
-			break
-		}
-		// Imaginary part always has a sign.
-		f.plus = true
-		f.space = false
-		f.wid = oldWid
-		r = j
-	}
-	f.space = oldSpace
-	f.plus = oldPlus
-	f.wid = oldWid
-	f.buf.Write(irparenBytes)
-}
diff --git a/libgo/go/fmt/print.go b/libgo/go/fmt/print.go
index ebfa13e4d37..f8c731656e5 100644
--- a/libgo/go/fmt/print.go
+++ b/libgo/go/fmt/print.go
@@ -13,24 +13,23 @@ import (
 	"unicode/utf8"
 )
 
-// Some constants in the form of bytes, to avoid string overhead.
-// Needlessly fastidious, I suppose.
-var (
-	commaSpaceBytes  = []byte(", ")
-	nilAngleBytes    = []byte("<nil>")
-	nilParenBytes    = []byte("(nil)")
-	nilBytes         = []byte("nil")
-	mapBytes         = []byte("map[")
-	percentBangBytes = []byte("%!")
-	missingBytes     = []byte("(MISSING)")
-	badIndexBytes    = []byte("(BADINDEX)")
-	panicBytes       = []byte("(PANIC=")
-	extraBytes       = []byte("%!(EXTRA ")
-	irparenBytes     = []byte("i)")
-	bytesBytes       = []byte("[]byte{")
-	badWidthBytes    = []byte("%!(BADWIDTH)")
-	badPrecBytes     = []byte("%!(BADPREC)")
-	noVerbBytes      = []byte("%!(NOVERB)")
+// Strings for use with buffer.WriteString.
+// This is less overhead than using buffer.Write with byte arrays.
+const (
+	commaSpaceString  = ", "
+	nilAngleString    = "<nil>"
+	nilParenString    = "(nil)"
+	nilString         = "nil"
+	mapString         = "map["
+	percentBangString = "%!"
+	missingString     = "(MISSING)"
+	badIndexString    = "(BADINDEX)"
+	panicString       = "(PANIC="
+	extraString       = "%!(EXTRA "
+	badWidthString    = "%!(BADWIDTH)"
+	badPrecString     = "%!(BADPREC)"
+	noVerbString      = "%!(NOVERB)"
+	invReflectString  = "<invalid reflect.Value>"
 )
 
 // State represents the printer state passed to custom formatters.
@@ -38,7 +37,7 @@ var (
 // the flags and options for the operand's format specifier.
 type State interface {
 	// Write is the function to call to emit formatted output to be printed.
-	Write(b []byte) (ret int, err error)
+	Write(b []byte) (n int, err error)
 	// Width returns the value of the width option and whether it has been set.
 	Width() (wid int, ok bool)
 	// Precision returns the value of the precision option and whether it has been set.
@@ -75,25 +74,22 @@ type GoStringer interface {
 // Use simple []byte instead of bytes.Buffer to avoid large dependency.
 type buffer []byte
 
-func (b *buffer) Write(p []byte) (n int, err error) {
+func (b *buffer) Write(p []byte) {
 	*b = append(*b, p...)
-	return len(p), nil
 }
 
-func (b *buffer) WriteString(s string) (n int, err error) {
+func (b *buffer) WriteString(s string) {
 	*b = append(*b, s...)
-	return len(s), nil
 }
 
-func (b *buffer) WriteByte(c byte) error {
+func (b *buffer) WriteByte(c byte) {
 	*b = append(*b, c)
-	return nil
 }
 
-func (bp *buffer) WriteRune(r rune) error {
+func (bp *buffer) WriteRune(r rune) {
 	if r < utf8.RuneSelf {
 		*bp = append(*bp, byte(r))
-		return nil
+		return
 	}
 
 	b := *bp
@@ -103,25 +99,29 @@ func (bp *buffer) WriteRune(r rune) error {
 	}
 	w := utf8.EncodeRune(b[n:n+utf8.UTFMax], r)
 	*bp = b[:n+w]
-	return nil
 }
 
+// pp is used to store a printer's state and is reused with sync.Pool to avoid allocations.
 type pp struct {
-	n         int
-	panicking bool
-	erroring  bool // printing an error condition
-	buf       buffer
+	buf buffer
+
 	// arg holds the current item, as an interface{}.
 	arg interface{}
-	// value holds the current item, as a reflect.Value, and will be
-	// the zero Value if the item has not been reflected.
+
+	// value is used instead of arg for reflect values.
 	value reflect.Value
+
+	// fmt is used to format basic items such as integers or strings.
+	fmt fmt
+
 	// reordered records whether the format string used argument reordering.
 	reordered bool
 	// goodArgNum records whether the most recent reordering directive was valid.
 	goodArgNum bool
-	runeBuf    [utf8.UTFMax]byte
-	fmt        fmt
+	// panicking is set by catchPanic to avoid infinite panic, recover, panic, ... recursion.
+	panicking bool
+	// erroring is set when printing an error string to guard against calling handleMethods.
+	erroring bool
 }
 
 var ppFree = sync.Pool{
@@ -139,10 +139,6 @@ func newPrinter() *pp {
 
 // free saves used pp structs in ppFree; avoids an allocation per invocation.
 func (p *pp) free() {
-	// Don't hold on to pp structs with large buffers.
-	if cap(p.buf) > 1024 {
-		return
-	}
 	p.buf = p.buf[:0]
 	p.arg = nil
 	p.value = reflect.Value{}
@@ -158,9 +154,9 @@ func (p *pp) Flag(b int) bool {
 	case '-':
 		return p.fmt.minus
 	case '+':
-		return p.fmt.plus
+		return p.fmt.plus || p.fmt.plusV
 	case '#':
-		return p.fmt.sharp
+		return p.fmt.sharp || p.fmt.sharpV
 	case ' ':
 		return p.fmt.space
 	case '0':
@@ -169,14 +165,11 @@ func (p *pp) Flag(b int) bool {
 	return false
 }
 
-func (p *pp) add(c rune) {
-	p.buf.WriteRune(c)
-}
-
 // Implement Write so we can call Fprintf on a pp (through State), for
 // recursive use in custom verbs.
 func (p *pp) Write(b []byte) (ret int, err error) {
-	return p.buf.Write(b)
+	p.buf.Write(b)
+	return len(b), nil
 }
 
 // These routines end in 'f' and take a format string.
@@ -219,7 +212,7 @@ func Errorf(format string, a ...interface{}) error {
 // It returns the number of bytes written and any write error encountered.
 func Fprint(w io.Writer, a ...interface{}) (n int, err error) {
 	p := newPrinter()
-	p.doPrint(a, false, false)
+	p.doPrint(a)
 	n, err = w.Write(p.buf)
 	p.free()
 	return
@@ -236,7 +229,7 @@ func Print(a ...interface{}) (n int, err error) {
 // Spaces are added between operands when neither is a string.
 func Sprint(a ...interface{}) string {
 	p := newPrinter()
-	p.doPrint(a, false, false)
+	p.doPrint(a)
 	s := string(p.buf)
 	p.free()
 	return s
@@ -251,7 +244,7 @@ func Sprint(a ...interface{}) string {
 // It returns the number of bytes written and any write error encountered.
 func Fprintln(w io.Writer, a ...interface{}) (n int, err error) {
 	p := newPrinter()
-	p.doPrint(a, true, true)
+	p.doPrintln(a)
 	n, err = w.Write(p.buf)
 	p.free()
 	return
@@ -268,7 +261,7 @@ func Println(a ...interface{}) (n int, err error) {
 // Spaces are always added between operands and a newline is appended.
 func Sprintln(a ...interface{}) string {
 	p := newPrinter()
-	p.doPrint(a, true, true)
+	p.doPrintln(a)
 	s := string(p.buf)
 	p.free()
 	return s
@@ -309,7 +302,7 @@ func parsenum(s string, start, end int) (num int, isnum bool, newi int) {
 
 func (p *pp) unknownType(v reflect.Value) {
 	if !v.IsValid() {
-		p.buf.Write(nilAngleBytes)
+		p.buf.WriteString(nilAngleString)
 		return
 	}
 	p.buf.WriteByte('?')
@@ -319,23 +312,22 @@ func (p *pp) unknownType(v reflect.Value) {
 
 func (p *pp) badVerb(verb rune) {
 	p.erroring = true
-	p.add('%')
-	p.add('!')
-	p.add(verb)
-	p.add('(')
+	p.buf.WriteString(percentBangString)
+	p.buf.WriteRune(verb)
+	p.buf.WriteByte('(')
 	switch {
 	case p.arg != nil:
 		p.buf.WriteString(reflect.TypeOf(p.arg).String())
-		p.add('=')
-		p.printArg(p.arg, 'v', 0)
+		p.buf.WriteByte('=')
+		p.printArg(p.arg, 'v')
 	case p.value.IsValid():
 		p.buf.WriteString(p.value.Type().String())
-		p.add('=')
+		p.buf.WriteByte('=')
 		p.printValue(p.value, 'v', 0)
 	default:
-		p.buf.Write(nilAngleBytes)
+		p.buf.WriteString(nilAngleString)
 	}
-	p.add(')')
+	p.buf.WriteByte(')')
 	p.erroring = false
 }
 
@@ -348,162 +340,82 @@ func (p *pp) fmtBool(v bool, verb rune) {
 	}
 }
 
-// fmtC formats a rune for the 'c' format.
-func (p *pp) fmtC(c int64) {
-	r := rune(c) // Check for overflow.
-	if int64(r) != c {
-		r = utf8.RuneError
-	}
-	w := utf8.EncodeRune(p.runeBuf[0:utf8.UTFMax], r)
-	p.fmt.pad(p.runeBuf[0:w])
-}
-
-func (p *pp) fmtInt64(v int64, verb rune) {
-	switch verb {
-	case 'b':
-		p.fmt.integer(v, 2, signed, ldigits)
-	case 'c':
-		p.fmtC(v)
-	case 'd', 'v':
-		p.fmt.integer(v, 10, signed, ldigits)
-	case 'o':
-		p.fmt.integer(v, 8, signed, ldigits)
-	case 'q':
-		if 0 <= v && v <= utf8.MaxRune {
-			p.fmt.fmt_qc(v)
-		} else {
-			p.badVerb(verb)
-		}
-	case 'x':
-		p.fmt.integer(v, 16, signed, ldigits)
-	case 'U':
-		p.fmtUnicode(v)
-	case 'X':
-		p.fmt.integer(v, 16, signed, udigits)
-	default:
-		p.badVerb(verb)
-	}
-}
-
 // fmt0x64 formats a uint64 in hexadecimal and prefixes it with 0x or
 // not, as requested, by temporarily setting the sharp flag.
 func (p *pp) fmt0x64(v uint64, leading0x bool) {
 	sharp := p.fmt.sharp
 	p.fmt.sharp = leading0x
-	p.fmt.integer(int64(v), 16, unsigned, ldigits)
+	p.fmt.fmt_integer(v, 16, unsigned, ldigits)
 	p.fmt.sharp = sharp
 }
 
-// fmtUnicode formats a uint64 in U+1234 form by
-// temporarily turning on the unicode flag and tweaking the precision.
-func (p *pp) fmtUnicode(v int64) {
-	precPresent := p.fmt.precPresent
-	sharp := p.fmt.sharp
-	p.fmt.sharp = false
-	prec := p.fmt.prec
-	if !precPresent {
-		// If prec is already set, leave it alone; otherwise 4 is minimum.
-		p.fmt.prec = 4
-		p.fmt.precPresent = true
-	}
-	p.fmt.unicode = true // turn on U+
-	p.fmt.uniQuote = sharp
-	p.fmt.integer(int64(v), 16, unsigned, udigits)
-	p.fmt.unicode = false
-	p.fmt.uniQuote = false
-	p.fmt.prec = prec
-	p.fmt.precPresent = precPresent
-	p.fmt.sharp = sharp
-}
-
-func (p *pp) fmtUint64(v uint64, verb rune) {
+// fmtInteger formats a signed or unsigned integer.
+func (p *pp) fmtInteger(v uint64, isSigned bool, verb rune) {
 	switch verb {
-	case 'b':
-		p.fmt.integer(int64(v), 2, unsigned, ldigits)
-	case 'c':
-		p.fmtC(int64(v))
-	case 'd':
-		p.fmt.integer(int64(v), 10, unsigned, ldigits)
 	case 'v':
-		if p.fmt.sharpV {
+		if p.fmt.sharpV && !isSigned {
 			p.fmt0x64(v, true)
 		} else {
-			p.fmt.integer(int64(v), 10, unsigned, ldigits)
+			p.fmt.fmt_integer(v, 10, isSigned, ldigits)
 		}
+	case 'd':
+		p.fmt.fmt_integer(v, 10, isSigned, ldigits)
+	case 'b':
+		p.fmt.fmt_integer(v, 2, isSigned, ldigits)
 	case 'o':
-		p.fmt.integer(int64(v), 8, unsigned, ldigits)
+		p.fmt.fmt_integer(v, 8, isSigned, ldigits)
+	case 'x':
+		p.fmt.fmt_integer(v, 16, isSigned, ldigits)
+	case 'X':
+		p.fmt.fmt_integer(v, 16, isSigned, udigits)
+	case 'c':
+		p.fmt.fmt_c(v)
 	case 'q':
-		if 0 <= v && v <= utf8.MaxRune {
-			p.fmt.fmt_qc(int64(v))
+		if v <= utf8.MaxRune {
+			p.fmt.fmt_qc(v)
 		} else {
 			p.badVerb(verb)
 		}
-	case 'x':
-		p.fmt.integer(int64(v), 16, unsigned, ldigits)
-	case 'X':
-		p.fmt.integer(int64(v), 16, unsigned, udigits)
 	case 'U':
-		p.fmtUnicode(int64(v))
+		p.fmt.fmt_unicode(v)
 	default:
 		p.badVerb(verb)
 	}
 }
 
-func (p *pp) fmtFloat32(v float32, verb rune) {
+// fmtFloat formats a float. The default precision for each verb
+// is specified as last argument in the call to fmt_float.
+func (p *pp) fmtFloat(v float64, size int, verb rune) {
 	switch verb {
-	case 'b':
-		p.fmt.fmt_fb32(v)
-	case 'e':
-		p.fmt.fmt_e32(v)
-	case 'E':
-		p.fmt.fmt_E32(v)
-	case 'f', 'F':
-		p.fmt.fmt_f32(v)
-	case 'g', 'v':
-		p.fmt.fmt_g32(v)
-	case 'G':
-		p.fmt.fmt_G32(v)
-	default:
-		p.badVerb(verb)
-	}
-}
-
-func (p *pp) fmtFloat64(v float64, verb rune) {
-	switch verb {
-	case 'b':
-		p.fmt.fmt_fb64(v)
-	case 'e':
-		p.fmt.fmt_e64(v)
-	case 'E':
-		p.fmt.fmt_E64(v)
-	case 'f', 'F':
-		p.fmt.fmt_f64(v)
-	case 'g', 'v':
-		p.fmt.fmt_g64(v)
-	case 'G':
-		p.fmt.fmt_G64(v)
-	default:
-		p.badVerb(verb)
-	}
-}
-
-func (p *pp) fmtComplex64(v complex64, verb rune) {
-	switch verb {
-	case 'b', 'e', 'E', 'f', 'F', 'g', 'G':
-		p.fmt.fmt_c64(v, verb)
 	case 'v':
-		p.fmt.fmt_c64(v, 'g')
+		p.fmt.fmt_float(v, size, 'g', -1)
+	case 'b', 'g', 'G':
+		p.fmt.fmt_float(v, size, verb, -1)
+	case 'f', 'e', 'E':
+		p.fmt.fmt_float(v, size, verb, 6)
+	case 'F':
+		p.fmt.fmt_float(v, size, 'f', 6)
 	default:
 		p.badVerb(verb)
 	}
 }
 
-func (p *pp) fmtComplex128(v complex128, verb rune) {
+// fmtComplex formats a complex number v with
+// r = real(v) and j = imag(v) as (r+ji) using
+// fmtFloat for r and j formatting.
+func (p *pp) fmtComplex(v complex128, size int, verb rune) {
+	// Make sure any unsupported verbs are found before the
+	// calls to fmtFloat to not generate an incorrect error string.
 	switch verb {
-	case 'b', 'e', 'E', 'f', 'F', 'g', 'G':
-		p.fmt.fmt_c128(v, verb)
-	case 'v':
-		p.fmt.fmt_c128(v, 'g')
+	case 'v', 'b', 'g', 'G', 'f', 'F', 'e', 'E':
+		oldPlus := p.fmt.plus
+		p.buf.WriteByte('(')
+		p.fmtFloat(real(v), size/2, verb)
+		// Imaginary part always has a sign.
+		p.fmt.plus = true
+		p.fmtFloat(imag(v), size/2, verb)
+		p.buf.WriteString("i)")
+		p.fmt.plus = oldPlus
 	default:
 		p.badVerb(verb)
 	}
@@ -530,45 +442,33 @@ func (p *pp) fmtString(v string, verb rune) {
 	}
 }
 
-func (p *pp) fmtBytes(v []byte, verb rune, typ reflect.Type, depth int) {
-	if verb == 'v' || verb == 'd' {
+func (p *pp) fmtBytes(v []byte, verb rune, typeString string) {
+	switch verb {
+	case 'v', 'd':
 		if p.fmt.sharpV {
+			p.buf.WriteString(typeString)
 			if v == nil {
-				if typ == nil {
-					p.buf.WriteString("[]byte(nil)")
-				} else {
-					p.buf.WriteString(typ.String())
-					p.buf.Write(nilParenBytes)
-				}
+				p.buf.WriteString(nilParenString)
 				return
 			}
-			if typ == nil {
-				p.buf.Write(bytesBytes)
-			} else {
-				p.buf.WriteString(typ.String())
-				p.buf.WriteByte('{')
+			p.buf.WriteByte('{')
+			for i, c := range v {
+				if i > 0 {
+					p.buf.WriteString(commaSpaceString)
+				}
+				p.fmt0x64(uint64(c), true)
 			}
+			p.buf.WriteByte('}')
 		} else {
 			p.buf.WriteByte('[')
-		}
-		for i, c := range v {
-			if i > 0 {
-				if p.fmt.sharpV {
-					p.buf.Write(commaSpaceBytes)
-				} else {
+			for i, c := range v {
+				if i > 0 {
 					p.buf.WriteByte(' ')
 				}
+				p.fmt.fmt_integer(uint64(c), 10, unsigned, ldigits)
 			}
-			p.printArg(c, 'v', depth+1)
-		}
-		if p.fmt.sharpV {
-			p.buf.WriteByte('}')
-		} else {
 			p.buf.WriteByte(']')
 		}
-		return
-	}
-	switch verb {
 	case 's':
 		p.fmt.fmt_s(string(v))
 	case 'x':
@@ -578,23 +478,11 @@ func (p *pp) fmtBytes(v []byte, verb rune, typ reflect.Type, depth int) {
 	case 'q':
 		p.fmt.fmt_q(string(v))
 	default:
-		p.badVerb(verb)
+		p.printValue(reflect.ValueOf(v), verb, 0)
 	}
 }
 
 func (p *pp) fmtPointer(value reflect.Value, verb rune) {
-	use0x64 := true
-	switch verb {
-	case 'p', 'v':
-		// ok
-	case 'b', 'd', 'o', 'x', 'X':
-		use0x64 = false
-		// ok
-	default:
-		p.badVerb(verb)
-		return
-	}
-
 	var u uintptr
 	switch value.Kind() {
 	case reflect.Chan, reflect.Func, reflect.Map, reflect.Ptr, reflect.Slice, reflect.UnsafePointer:
@@ -604,40 +492,41 @@ func (p *pp) fmtPointer(value reflect.Value, verb rune) {
 		return
 	}
 
-	if p.fmt.sharpV {
-		p.add('(')
-		p.buf.WriteString(value.Type().String())
-		p.add(')')
-		p.add('(')
-		if u == 0 {
-			p.buf.Write(nilBytes)
-		} else {
-			p.fmt0x64(uint64(u), true)
-		}
-		p.add(')')
-	} else if verb == 'v' && u == 0 {
-		p.buf.Write(nilAngleBytes)
-	} else {
-		if use0x64 {
-			p.fmt0x64(uint64(u), !p.fmt.sharp)
+	switch verb {
+	case 'v':
+		if p.fmt.sharpV {
+			p.buf.WriteByte('(')
+			p.buf.WriteString(value.Type().String())
+			p.buf.WriteString(")(")
+			if u == 0 {
+				p.buf.WriteString(nilString)
+			} else {
+				p.fmt0x64(uint64(u), true)
+			}
+			p.buf.WriteByte(')')
 		} else {
-			p.fmtUint64(uint64(u), verb)
+			if u == 0 {
+				p.fmt.padString(nilAngleString)
+			} else {
+				p.fmt0x64(uint64(u), !p.fmt.sharp)
+			}
 		}
+	case 'p':
+		p.fmt0x64(uint64(u), !p.fmt.sharp)
+	case 'b', 'o', 'd', 'x', 'X':
+		p.fmtInteger(uint64(u), unsigned, verb)
+	default:
+		p.badVerb(verb)
 	}
 }
 
-var (
-	intBits     = reflect.TypeOf(0).Bits()
-	uintptrBits = reflect.TypeOf(uintptr(0)).Bits()
-)
-
 func (p *pp) catchPanic(arg interface{}, verb rune) {
 	if err := recover(); err != nil {
 		// If it's a nil pointer, just say "<nil>". The likeliest causes are a
 		// Stringer that fails to guard against nil or a nil pointer for a
 		// value receiver, and in either case, "<nil>" is a nice result.
 		if v := reflect.ValueOf(arg); v.Kind() == reflect.Ptr && v.IsNil() {
-			p.buf.Write(nilAngleBytes)
+			p.buf.WriteString(nilAngleString)
 			return
 		}
 		// Otherwise print a concise panic message. Most of the time the panic
@@ -647,52 +536,23 @@ func (p *pp) catchPanic(arg interface{}, verb rune) {
 			panic(err)
 		}
 		p.fmt.clearflags() // We are done, and for this output we want default behavior.
-		p.buf.Write(percentBangBytes)
-		p.add(verb)
-		p.buf.Write(panicBytes)
+		p.buf.WriteString(percentBangString)
+		p.buf.WriteRune(verb)
+		p.buf.WriteString(panicString)
 		p.panicking = true
-		p.printArg(err, 'v', 0)
+		p.printArg(err, 'v')
 		p.panicking = false
 		p.buf.WriteByte(')')
 	}
 }
 
-// clearSpecialFlags pushes %#v back into the regular flags and returns their old state.
-func (p *pp) clearSpecialFlags() (plusV, sharpV bool) {
-	plusV = p.fmt.plusV
-	if plusV {
-		p.fmt.plus = true
-		p.fmt.plusV = false
-	}
-	sharpV = p.fmt.sharpV
-	if sharpV {
-		p.fmt.sharp = true
-		p.fmt.sharpV = false
-	}
-	return
-}
-
-// restoreSpecialFlags, whose argument should be a call to clearSpecialFlags,
-// restores the setting of the plusV and sharpV flags.
-func (p *pp) restoreSpecialFlags(plusV, sharpV bool) {
-	if plusV {
-		p.fmt.plus = false
-		p.fmt.plusV = true
-	}
-	if sharpV {
-		p.fmt.sharp = false
-		p.fmt.sharpV = true
-	}
-}
-
-func (p *pp) handleMethods(verb rune, depth int) (handled bool) {
+func (p *pp) handleMethods(verb rune) (handled bool) {
 	if p.erroring {
 		return
 	}
 	// Is it a Formatter?
 	if formatter, ok := p.arg.(Formatter); ok {
 		handled = true
-		defer p.restoreSpecialFlags(p.clearSpecialFlags())
 		defer p.catchPanic(p.arg, verb)
 		formatter.Format(p, verb)
 		return
@@ -721,13 +581,13 @@ func (p *pp) handleMethods(verb rune, depth int) (handled bool) {
 			case error:
 				handled = true
 				defer p.catchPanic(p.arg, verb)
-				p.printArg(v.Error(), verb, depth)
+				p.fmtString(v.Error(), verb)
 				return
 
 			case Stringer:
 				handled = true
 				defer p.catchPanic(p.arg, verb)
-				p.printArg(v.String(), verb, depth)
+				p.fmtString(v.String(), verb)
 				return
 			}
 		}
@@ -735,28 +595,29 @@ func (p *pp) handleMethods(verb rune, depth int) (handled bool) {
 	return false
 }
 
-func (p *pp) printArg(arg interface{}, verb rune, depth int) (wasString bool) {
+func (p *pp) printArg(arg interface{}, verb rune) {
 	p.arg = arg
 	p.value = reflect.Value{}
 
 	if arg == nil {
-		if verb == 'T' || verb == 'v' {
-			p.fmt.pad(nilAngleBytes)
-		} else {
+		switch verb {
+		case 'T', 'v':
+			p.fmt.padString(nilAngleString)
+		default:
 			p.badVerb(verb)
 		}
-		return false
+		return
 	}
 
 	// Special processing considerations.
 	// %T (the value's type) and %p (its address) are special; we always do them first.
 	switch verb {
 	case 'T':
-		p.printArg(reflect.TypeOf(arg).String(), 's', 0)
-		return false
+		p.fmt.fmt_s(reflect.TypeOf(arg).String())
+		return
 	case 'p':
-		p.fmtPointer(reflect.ValueOf(arg), verb)
-		return false
+		p.fmtPointer(reflect.ValueOf(arg), 'p')
+		return
 	}
 
 	// Some types can be done without reflection.
@@ -764,137 +625,110 @@ func (p *pp) printArg(arg interface{}, verb rune, depth int) (wasString bool) {
 	case bool:
 		p.fmtBool(f, verb)
 	case float32:
-		p.fmtFloat32(f, verb)
+		p.fmtFloat(float64(f), 32, verb)
 	case float64:
-		p.fmtFloat64(f, verb)
+		p.fmtFloat(f, 64, verb)
 	case complex64:
-		p.fmtComplex64(f, verb)
+		p.fmtComplex(complex128(f), 64, verb)
 	case complex128:
-		p.fmtComplex128(f, verb)
+		p.fmtComplex(f, 128, verb)
 	case int:
-		p.fmtInt64(int64(f), verb)
+		p.fmtInteger(uint64(f), signed, verb)
 	case int8:
-		p.fmtInt64(int64(f), verb)
+		p.fmtInteger(uint64(f), signed, verb)
 	case int16:
-		p.fmtInt64(int64(f), verb)
+		p.fmtInteger(uint64(f), signed, verb)
 	case int32:
-		p.fmtInt64(int64(f), verb)
+		p.fmtInteger(uint64(f), signed, verb)
 	case int64:
-		p.fmtInt64(f, verb)
+		p.fmtInteger(uint64(f), signed, verb)
 	case uint:
-		p.fmtUint64(uint64(f), verb)
+		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint8:
-		p.fmtUint64(uint64(f), verb)
+		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint16:
-		p.fmtUint64(uint64(f), verb)
+		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint32:
-		p.fmtUint64(uint64(f), verb)
+		p.fmtInteger(uint64(f), unsigned, verb)
 	case uint64:
-		p.fmtUint64(f, verb)
+		p.fmtInteger(f, unsigned, verb)
 	case uintptr:
-		p.fmtUint64(uint64(f), verb)
+		p.fmtInteger(uint64(f), unsigned, verb)
 	case string:
 		p.fmtString(f, verb)
-		wasString = verb == 's' || verb == 'v'
 	case []byte:
-		p.fmtBytes(f, verb, nil, depth)
-		wasString = verb == 's'
+		p.fmtBytes(f, verb, "[]byte")
 	case reflect.Value:
-		return p.printReflectValue(f, verb, depth)
+		p.printValue(f, verb, 0)
 	default:
 		// If the type is not simple, it might have methods.
-		if handled := p.handleMethods(verb, depth); handled {
-			return false
+		if !p.handleMethods(verb) {
+			// Need to use reflection, since the type had no
+			// interface methods that could be used for formatting.
+			p.printValue(reflect.ValueOf(f), verb, 0)
 		}
-		// Need to use reflection
-		return p.printReflectValue(reflect.ValueOf(arg), verb, depth)
 	}
-	p.arg = nil
-	return
 }
 
-// printValue is like printArg but starts with a reflect value, not an interface{} value.
-func (p *pp) printValue(value reflect.Value, verb rune, depth int) (wasString bool) {
-	if !value.IsValid() {
-		if verb == 'T' || verb == 'v' {
-			p.buf.Write(nilAngleBytes)
-		} else {
-			p.badVerb(verb)
-		}
-		return false
-	}
-
-	// Special processing considerations.
-	// %T (the value's type) and %p (its address) are special; we always do them first.
-	switch verb {
-	case 'T':
-		p.printArg(value.Type().String(), 's', 0)
-		return false
-	case 'p':
-		p.fmtPointer(value, verb)
-		return false
-	}
+var byteType = reflect.TypeOf(byte(0))
 
-	// Handle values with special methods.
-	// Call always, even when arg == nil, because handleMethods clears p.fmt.plus for us.
-	p.arg = nil // Make sure it's cleared, for safety.
-	if value.CanInterface() {
+// printValue is similar to printArg but starts with a reflect value, not an interface{} value.
+// It does not handle 'p' and 'T' verbs because these should have been already handled by printArg.
+func (p *pp) printValue(value reflect.Value, verb rune, depth int) {
+	// Handle values with special methods if not already handled by printArg (depth == 0).
+	if depth > 0 && value.IsValid() && value.CanInterface() {
 		p.arg = value.Interface()
+		if p.handleMethods(verb) {
+			return
+		}
 	}
-	if handled := p.handleMethods(verb, depth); handled {
-		return false
-	}
-
-	return p.printReflectValue(value, verb, depth)
-}
-
-var byteType = reflect.TypeOf(byte(0))
-
-// printReflectValue is the fallback for both printArg and printValue.
-// It uses reflect to print the value.
-func (p *pp) printReflectValue(value reflect.Value, verb rune, depth int) (wasString bool) {
-	oldValue := p.value
+	p.arg = nil
 	p.value = value
-BigSwitch:
-	switch f := value; f.Kind() {
+
+	switch f := value; value.Kind() {
 	case reflect.Invalid:
-		p.buf.WriteString("<invalid reflect.Value>")
+		if depth == 0 {
+			p.buf.WriteString(invReflectString)
+		} else {
+			switch verb {
+			case 'v':
+				p.buf.WriteString(nilAngleString)
+			default:
+				p.badVerb(verb)
+			}
+		}
 	case reflect.Bool:
 		p.fmtBool(f.Bool(), verb)
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		p.fmtInt64(f.Int(), verb)
+		p.fmtInteger(uint64(f.Int()), signed, verb)
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		p.fmtUint64(f.Uint(), verb)
-	case reflect.Float32, reflect.Float64:
-		if f.Type().Size() == 4 {
-			p.fmtFloat32(float32(f.Float()), verb)
-		} else {
-			p.fmtFloat64(f.Float(), verb)
-		}
-	case reflect.Complex64, reflect.Complex128:
-		if f.Type().Size() == 8 {
-			p.fmtComplex64(complex64(f.Complex()), verb)
-		} else {
-			p.fmtComplex128(f.Complex(), verb)
-		}
+		p.fmtInteger(f.Uint(), unsigned, verb)
+	case reflect.Float32:
+		p.fmtFloat(f.Float(), 32, verb)
+	case reflect.Float64:
+		p.fmtFloat(f.Float(), 64, verb)
+	case reflect.Complex64:
+		p.fmtComplex(f.Complex(), 64, verb)
+	case reflect.Complex128:
+		p.fmtComplex(f.Complex(), 128, verb)
 	case reflect.String:
 		p.fmtString(f.String(), verb)
 	case reflect.Map:
 		if p.fmt.sharpV {
 			p.buf.WriteString(f.Type().String())
 			if f.IsNil() {
-				p.buf.WriteString("(nil)")
-				break
+				p.buf.WriteString(nilParenString)
+				return
 			}
 			p.buf.WriteByte('{')
 		} else {
-			p.buf.Write(mapBytes)
+			p.buf.WriteString(mapString)
 		}
 		keys := f.MapKeys()
 		for i, key := range keys {
 			if i > 0 {
 				if p.fmt.sharpV {
-					p.buf.Write(commaSpaceBytes)
+					p.buf.WriteString(commaSpaceString)
 				} else {
 					p.buf.WriteByte(' ')
 				}
@@ -910,26 +744,24 @@ BigSwitch:
 		}
 	case reflect.Struct:
 		if p.fmt.sharpV {
-			p.buf.WriteString(value.Type().String())
+			p.buf.WriteString(f.Type().String())
 		}
-		p.add('{')
-		v := f
-		t := v.Type()
-		for i := 0; i < v.NumField(); i++ {
+		p.buf.WriteByte('{')
+		for i := 0; i < f.NumField(); i++ {
 			if i > 0 {
 				if p.fmt.sharpV {
-					p.buf.Write(commaSpaceBytes)
+					p.buf.WriteString(commaSpaceString)
 				} else {
 					p.buf.WriteByte(' ')
 				}
 			}
 			if p.fmt.plusV || p.fmt.sharpV {
-				if f := t.Field(i); f.Name != "" {
-					p.buf.WriteString(f.Name)
+				if name := f.Type().Field(i).Name; name != "" {
+					p.buf.WriteString(name)
 					p.buf.WriteByte(':')
 				}
 			}
-			p.printValue(getField(v, i), verb, depth+1)
+			p.printValue(getField(f, i), verb, depth+1)
 		}
 		p.buf.WriteByte('}')
 	case reflect.Interface:
@@ -937,91 +769,79 @@ BigSwitch:
 		if !value.IsValid() {
 			if p.fmt.sharpV {
 				p.buf.WriteString(f.Type().String())
-				p.buf.Write(nilParenBytes)
+				p.buf.WriteString(nilParenString)
 			} else {
-				p.buf.Write(nilAngleBytes)
+				p.buf.WriteString(nilAngleString)
 			}
 		} else {
-			wasString = p.printValue(value, verb, depth+1)
+			p.printValue(value, verb, depth+1)
 		}
 	case reflect.Array, reflect.Slice:
-		// Byte slices are special:
-		// - Handle []byte (== []uint8) with fmtBytes.
-		// - Handle []T, where T is a named byte type, with fmtBytes only
-		//   for the s, q, an x verbs. For other verbs, T might be a
-		//   Stringer, so we use printValue to print each element.
-		if typ := f.Type(); typ.Elem().Kind() == reflect.Uint8 && (typ.Elem() == byteType || verb == 's' || verb == 'q' || verb == 'x') {
-			var bytes []byte
-			if f.Kind() == reflect.Slice {
-				bytes = f.Bytes()
-			} else if f.CanAddr() {
-				bytes = f.Slice(0, f.Len()).Bytes()
-			} else {
-				// We have an array, but we cannot Slice() a non-addressable array,
-				// so we build a slice by hand. This is a rare case but it would be nice
-				// if reflection could help a little more.
-				bytes = make([]byte, f.Len())
-				for i := range bytes {
-					bytes[i] = byte(f.Index(i).Uint())
+		switch verb {
+		case 's', 'q', 'x', 'X':
+			// Handle byte and uint8 slices and arrays special for the above verbs.
+			t := f.Type()
+			if t.Elem().Kind() == reflect.Uint8 {
+				var bytes []byte
+				if f.Kind() == reflect.Slice {
+					bytes = f.Bytes()
+				} else if f.CanAddr() {
+					bytes = f.Slice(0, f.Len()).Bytes()
+				} else {
+					// We have an array, but we cannot Slice() a non-addressable array,
+					// so we build a slice by hand. This is a rare case but it would be nice
+					// if reflection could help a little more.
+					bytes = make([]byte, f.Len())
+					for i := range bytes {
+						bytes[i] = byte(f.Index(i).Uint())
+					}
 				}
+				p.fmtBytes(bytes, verb, t.String())
+				return
 			}
-			p.fmtBytes(bytes, verb, typ, depth)
-			wasString = verb == 's'
-			break
 		}
 		if p.fmt.sharpV {
-			p.buf.WriteString(value.Type().String())
+			p.buf.WriteString(f.Type().String())
 			if f.Kind() == reflect.Slice && f.IsNil() {
-				p.buf.WriteString("(nil)")
-				break
+				p.buf.WriteString(nilParenString)
+				return
+			} else {
+				p.buf.WriteByte('{')
+				for i := 0; i < f.Len(); i++ {
+					if i > 0 {
+						p.buf.WriteString(commaSpaceString)
+					}
+					p.printValue(f.Index(i), verb, depth+1)
+				}
+				p.buf.WriteByte('}')
 			}
-			p.buf.WriteByte('{')
 		} else {
 			p.buf.WriteByte('[')
-		}
-		for i := 0; i < f.Len(); i++ {
-			if i > 0 {
-				if p.fmt.sharpV {
-					p.buf.Write(commaSpaceBytes)
-				} else {
+			for i := 0; i < f.Len(); i++ {
+				if i > 0 {
 					p.buf.WriteByte(' ')
 				}
+				p.printValue(f.Index(i), verb, depth+1)
 			}
-			p.printValue(f.Index(i), verb, depth+1)
-		}
-		if p.fmt.sharpV {
-			p.buf.WriteByte('}')
-		} else {
 			p.buf.WriteByte(']')
 		}
 	case reflect.Ptr:
-		v := f.Pointer()
 		// pointer to array or slice or struct?  ok at top level
 		// but not embedded (avoid loops)
-		if v != 0 && depth == 0 {
+		if depth == 0 && f.Pointer() != 0 {
 			switch a := f.Elem(); a.Kind() {
-			case reflect.Array, reflect.Slice:
-				p.buf.WriteByte('&')
-				p.printValue(a, verb, depth+1)
-				break BigSwitch
-			case reflect.Struct:
-				p.buf.WriteByte('&')
-				p.printValue(a, verb, depth+1)
-				break BigSwitch
-			case reflect.Map:
+			case reflect.Array, reflect.Slice, reflect.Struct, reflect.Map:
 				p.buf.WriteByte('&')
 				p.printValue(a, verb, depth+1)
-				break BigSwitch
+				return
 			}
 		}
 		fallthrough
 	case reflect.Chan, reflect.Func, reflect.UnsafePointer:
-		p.fmtPointer(value, verb)
+		p.fmtPointer(f, verb)
 	default:
 		p.unknownType(f)
 	}
-	p.value = oldValue
-	return wasString
 }
 
 // intFromArg gets the argNumth element of a. On return, isInt reports whether the argument has integer type.
@@ -1098,11 +918,24 @@ func (p *pp) argNumber(argNum int, format string, i int, numArgs int) (newArgNum
 	return argNum, i + wid, ok
 }
 
+func (p *pp) badArgNum(verb rune) {
+	p.buf.WriteString(percentBangString)
+	p.buf.WriteRune(verb)
+	p.buf.WriteString(badIndexString)
+}
+
+func (p *pp) missingArg(verb rune) {
+	p.buf.WriteString(percentBangString)
+	p.buf.WriteRune(verb)
+	p.buf.WriteString(missingString)
+}
+
 func (p *pp) doPrintf(format string, a []interface{}) {
 	end := len(format)
 	argNum := 0         // we process one argument per non-trivial format
 	afterIndex := false // previous item in format was an index like [3].
 	p.reordered = false
+formatLoop:
 	for i := 0; i < end; {
 		p.goodArgNum = true
 		lasti := i
@@ -1122,21 +955,40 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 
 		// Do we have flags?
 		p.fmt.clearflags()
-	F:
+	simpleFormat:
 		for ; i < end; i++ {
-			switch format[i] {
+			c := format[i]
+			switch c {
 			case '#':
 				p.fmt.sharp = true
 			case '0':
-				p.fmt.zero = true
+				p.fmt.zero = !p.fmt.minus // Only allow zero padding to the left.
 			case '+':
 				p.fmt.plus = true
 			case '-':
 				p.fmt.minus = true
+				p.fmt.zero = false // Do not pad with zeros to the right.
 			case ' ':
 				p.fmt.space = true
 			default:
-				break F
+				// Fast path for common case of ascii lower case simple verbs
+				// without precision or width or argument indices.
+				if 'a' <= c && c <= 'z' && argNum < len(a) {
+					if c == 'v' {
+						// Go syntax
+						p.fmt.sharpV = p.fmt.sharp
+						p.fmt.sharp = false
+						// Struct-field syntax
+						p.fmt.plusV = p.fmt.plus
+						p.fmt.plus = false
+					}
+					p.printArg(a[argNum], rune(c))
+					argNum++
+					i++
+					continue formatLoop
+				}
+				// Format is more complex than simple flags and a verb or is malformed.
+				break simpleFormat
 			}
 		}
 
@@ -1149,7 +1001,7 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 			p.fmt.wid, p.fmt.widPresent, argNum = intFromArg(a, argNum)
 
 			if !p.fmt.widPresent {
-				p.buf.Write(badWidthBytes)
+				p.buf.WriteString(badWidthString)
 			}
 
 			// We have a negative width, so take its value and ensure
@@ -1157,6 +1009,7 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 			if p.fmt.wid < 0 {
 				p.fmt.wid = -p.fmt.wid
 				p.fmt.minus = true
+				p.fmt.zero = false // Do not pad with zeros to the right.
 			}
 			afterIndex = false
 		} else {
@@ -1182,7 +1035,7 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 					p.fmt.precPresent = false
 				}
 				if !p.fmt.precPresent {
-					p.buf.Write(badPrecBytes)
+					p.buf.WriteString(badPrecString)
 				}
 				afterIndex = false
 			} else {
@@ -1199,80 +1052,77 @@ func (p *pp) doPrintf(format string, a []interface{}) {
 		}
 
 		if i >= end {
-			p.buf.Write(noVerbBytes)
-			continue
+			p.buf.WriteString(noVerbString)
+			break
 		}
-		c, w := utf8.DecodeRuneInString(format[i:])
+
+		verb, w := utf8.DecodeRuneInString(format[i:])
 		i += w
-		// percent is special - absorbs no operand
-		if c == '%' {
-			p.buf.WriteByte('%') // We ignore width and prec.
-			continue
-		}
-		if !p.goodArgNum {
-			p.buf.Write(percentBangBytes)
-			p.add(c)
-			p.buf.Write(badIndexBytes)
-			continue
-		} else if argNum >= len(a) { // out of operands
-			p.buf.Write(percentBangBytes)
-			p.add(c)
-			p.buf.Write(missingBytes)
-			continue
-		}
-		arg := a[argNum]
-		argNum++
-
-		if c == 'v' {
-			if p.fmt.sharp {
-				// Go syntax. Set the flag in the fmt and clear the sharp flag.
-				p.fmt.sharp = false
-				p.fmt.sharpV = true
-			}
-			if p.fmt.plus {
-				// Struct-field syntax. Set the flag in the fmt and clear the plus flag.
-				p.fmt.plus = false
-				p.fmt.plusV = true
-			}
+
+		switch {
+		case verb == '%': // Percent does not absorb operands and ignores f.wid and f.prec.
+			p.buf.WriteByte('%')
+		case !p.goodArgNum:
+			p.badArgNum(verb)
+		case argNum >= len(a): // No argument left over to print for the current verb.
+			p.missingArg(verb)
+		case verb == 'v':
+			// Go syntax
+			p.fmt.sharpV = p.fmt.sharp
+			p.fmt.sharp = false
+			// Struct-field syntax
+			p.fmt.plusV = p.fmt.plus
+			p.fmt.plus = false
+			fallthrough
+		default:
+			p.printArg(a[argNum], verb)
+			argNum++
 		}
-		p.printArg(arg, c, 0)
 	}
 
 	// Check for extra arguments unless the call accessed the arguments
 	// out of order, in which case it's too expensive to detect if they've all
 	// been used and arguably OK if they're not.
 	if !p.reordered && argNum < len(a) {
-		p.buf.Write(extraBytes)
-		for ; argNum < len(a); argNum++ {
-			arg := a[argNum]
-			if arg != nil {
+		p.fmt.clearflags()
+		p.buf.WriteString(extraString)
+		for i, arg := range a[argNum:] {
+			if i > 0 {
+				p.buf.WriteString(commaSpaceString)
+			}
+			if arg == nil {
+				p.buf.WriteString(nilAngleString)
+			} else {
 				p.buf.WriteString(reflect.TypeOf(arg).String())
 				p.buf.WriteByte('=')
-			}
-			p.printArg(arg, 'v', 0)
-			if argNum+1 < len(a) {
-				p.buf.Write(commaSpaceBytes)
+				p.printArg(arg, 'v')
 			}
 		}
 		p.buf.WriteByte(')')
 	}
 }
 
-func (p *pp) doPrint(a []interface{}, addspace, addnewline bool) {
+func (p *pp) doPrint(a []interface{}) {
 	prevString := false
-	for argNum := 0; argNum < len(a); argNum++ {
-		p.fmt.clearflags()
-		// always add spaces if we're doing Println
-		arg := a[argNum]
-		if argNum > 0 {
-			isString := arg != nil && reflect.TypeOf(arg).Kind() == reflect.String
-			if addspace || !isString && !prevString {
-				p.buf.WriteByte(' ')
-			}
+	for argNum, arg := range a {
+		isString := arg != nil && reflect.TypeOf(arg).Kind() == reflect.String
+		// Add a space between two non-string arguments.
+		if argNum > 0 && !isString && !prevString {
+			p.buf.WriteByte(' ')
 		}
-		prevString = p.printArg(arg, 'v', 0)
+		p.printArg(arg, 'v')
+		prevString = isString
 	}
-	if addnewline {
-		p.buf.WriteByte('\n')
+}
+
+// doPrintln is like doPrint but always adds a space between arguments
+// and a newline after the last argument.
+func (p *pp) doPrintln(a []interface{}) {
+	for argNum, arg := range a {
+		if argNum > 0 {
+			p.buf.WriteByte(' ')
+		}
+		p.printArg(arg, 'v')
 	}
+	p.buf.WriteByte('\n')
 }
diff --git a/libgo/go/fmt/scan.go b/libgo/go/fmt/scan.go
index 4618ed4a827..fdf419795d9 100644
--- a/libgo/go/fmt/scan.go
+++ b/libgo/go/fmt/scan.go
@@ -15,14 +15,6 @@ import (
 	"unicode/utf8"
 )
 
-// runeUnreader is the interface to something that can unread runes.
-// If the object provided to Scan does not satisfy this interface,
-// a local buffer will be used to back up the input, but its contents
-// will be lost when Scan returns.
-type runeUnreader interface {
-	UnreadRune() error
-}
-
 // ScanState represents the scanner state passed to custom scanners.
 // Scanners may do rune-at-a-time scanning or ask the ScanState
 // to discover the next space-delimited token.
@@ -41,7 +33,7 @@ type ScanState interface {
 	// Token skips space in the input if skipSpace is true, then returns the
 	// run of Unicode code points c satisfying f(c).  If f is nil,
 	// !unicode.IsSpace(c) is used; that is, the token will hold non-space
-	// characters.  Newlines are treated appropriately for the operation being
+	// characters. Newlines are treated appropriately for the operation being
 	// performed; see the package documentation for more information.
 	// The returned slice points to shared data that may be overwritten
 	// by the next call to Token, a call to a Scan function using the ScanState
@@ -58,15 +50,15 @@ type ScanState interface {
 
 // Scanner is implemented by any value that has a Scan method, which scans
 // the input for the representation of a value and stores the result in the
-// receiver, which must be a pointer to be useful.  The Scan method is called
+// receiver, which must be a pointer to be useful. The Scan method is called
 // for any argument to Scan, Scanf, or Scanln that implements it.
 type Scanner interface {
 	Scan(state ScanState, verb rune) error
 }
 
 // Scan scans text read from standard input, storing successive
-// space-separated values into successive arguments.  Newlines count
-// as space.  It returns the number of items successfully scanned.
+// space-separated values into successive arguments. Newlines count
+// as space. It returns the number of items successfully scanned.
 // If that is less than the number of arguments, err will report why.
 func Scan(a ...interface{}) (n int, err error) {
 	return Fscan(os.Stdin, a...)
@@ -80,7 +72,7 @@ func Scanln(a ...interface{}) (n int, err error) {
 
 // Scanf scans text read from standard input, storing successive
 // space-separated values into successive arguments as determined by
-// the format.  It returns the number of items successfully scanned.
+// the format. It returns the number of items successfully scanned.
 // If that is less than the number of arguments, err will report why.
 // Newlines in the input must match newlines in the format.
 // The one exception: the verb %c always scans the next rune in the
@@ -101,8 +93,8 @@ func (r *stringReader) Read(b []byte) (n int, err error) {
 }
 
 // Sscan scans the argument string, storing successive space-separated
-// values into successive arguments.  Newlines count as space.  It
-// returns the number of items successfully scanned.  If that is less
+// values into successive arguments. Newlines count as space. It
+// returns the number of items successfully scanned. If that is less
 // than the number of arguments, err will report why.
 func Sscan(str string, a ...interface{}) (n int, err error) {
 	return Fscan((*stringReader)(&str), a...)
@@ -115,7 +107,7 @@ func Sscanln(str string, a ...interface{}) (n int, err error) {
 }
 
 // Sscanf scans the argument string, storing successive space-separated
-// values into successive arguments as determined by the format.  It
+// values into successive arguments as determined by the format. It
 // returns the number of items successfully parsed.
 // Newlines in the input must match newlines in the format.
 func Sscanf(str string, format string, a ...interface{}) (n int, err error) {
@@ -123,8 +115,8 @@ func Sscanf(str string, format string, a ...interface{}) (n int, err error) {
 }
 
 // Fscan scans text read from r, storing successive space-separated
-// values into successive arguments.  Newlines count as space.  It
-// returns the number of items successfully scanned.  If that is less
+// values into successive arguments. Newlines count as space. It
+// returns the number of items successfully scanned. If that is less
 // than the number of arguments, err will report why.
 func Fscan(r io.Reader, a ...interface{}) (n int, err error) {
 	s, old := newScanState(r, true, false)
@@ -143,7 +135,7 @@ func Fscanln(r io.Reader, a ...interface{}) (n int, err error) {
 }
 
 // Fscanf scans text read from r, storing successive space-separated
-// values into successive arguments as determined by the format.  It
+// values into successive arguments as determined by the format. It
 // returns the number of items successfully parsed.
 // Newlines in the input must match newlines in the format.
 func Fscanf(r io.Reader, format string, a ...interface{}) (n int, err error) {
@@ -163,12 +155,10 @@ const eof = -1
 
 // ss is the internal implementation of ScanState.
 type ss struct {
-	rr       io.RuneReader // where to read input
-	buf      buffer        // token accumulator
-	peekRune rune          // one-rune lookahead
-	prevRune rune          // last rune returned by ReadRune
-	count    int           // runes consumed so far.
-	atEOF    bool          // already read EOF
+	rs    io.RuneScanner // where to read input
+	buf   buffer         // token accumulator
+	count int            // runes consumed so far.
+	atEOF bool           // already read EOF
 	ssave
 }
 
@@ -191,23 +181,17 @@ func (s *ss) Read(buf []byte) (n int, err error) {
 }
 
 func (s *ss) ReadRune() (r rune, size int, err error) {
-	if s.peekRune >= 0 {
-		s.count++
-		r = s.peekRune
-		size = utf8.RuneLen(r)
-		s.prevRune = r
-		s.peekRune = -1
-		return
-	}
-	if s.atEOF || s.nlIsEnd && s.prevRune == '\n' || s.count >= s.argLimit {
+	if s.atEOF || s.count >= s.argLimit {
 		err = io.EOF
 		return
 	}
 
-	r, size, err = s.rr.ReadRune()
+	r, size, err = s.rs.ReadRune()
 	if err == nil {
 		s.count++
-		s.prevRune = r
+		if s.nlIsEnd && r == '\n' {
+			s.atEOF = true
+		}
 	} else if err == io.EOF {
 		s.atEOF = true
 	}
@@ -246,12 +230,8 @@ func (s *ss) mustReadRune() (r rune) {
 }
 
 func (s *ss) UnreadRune() error {
-	if u, ok := s.rr.(runeUnreader); ok {
-		u.UnreadRune()
-	} else {
-		s.peekRune = s.prevRune
-	}
-	s.prevRune = -1
+	s.rs.UnreadRune()
+	s.atEOF = false
 	s.count--
 	return nil
 }
@@ -326,13 +306,14 @@ func (s *ss) SkipSpace() {
 }
 
 // readRune is a structure to enable reading UTF-8 encoded code points
-// from an io.Reader.  It is used if the Reader given to the scanner does
-// not already implement io.RuneReader.
+// from an io.Reader. It is used if the Reader given to the scanner does
+// not already implement io.RuneScanner.
 type readRune struct {
-	reader  io.Reader
-	buf     [utf8.UTFMax]byte // used only inside ReadRune
-	pending int               // number of bytes in pendBuf; only >0 for bad UTF-8
-	pendBuf [utf8.UTFMax]byte // bytes left over
+	reader   io.Reader
+	buf      [utf8.UTFMax]byte // used only inside ReadRune
+	pending  int               // number of bytes in pendBuf; only >0 for bad UTF-8
+	pendBuf  [utf8.UTFMax]byte // bytes left over
+	peekRune rune              // if >=0 next rune; when <0 is ^(previous Rune)
 }
 
 // readByte returns the next byte from the input, which may be
@@ -344,33 +325,35 @@ func (r *readRune) readByte() (b byte, err error) {
 		r.pending--
 		return
 	}
-	n, err := io.ReadFull(r.reader, r.pendBuf[0:1])
+	n, err := io.ReadFull(r.reader, r.pendBuf[:1])
 	if n != 1 {
 		return 0, err
 	}
 	return r.pendBuf[0], err
 }
 
-// unread saves the bytes for the next read.
-func (r *readRune) unread(buf []byte) {
-	copy(r.pendBuf[r.pending:], buf)
-	r.pending += len(buf)
-}
-
 // ReadRune returns the next UTF-8 encoded code point from the
 // io.Reader inside r.
 func (r *readRune) ReadRune() (rr rune, size int, err error) {
+	if r.peekRune >= 0 {
+		rr = r.peekRune
+		r.peekRune = ^r.peekRune
+		size = utf8.RuneLen(rr)
+		return
+	}
 	r.buf[0], err = r.readByte()
 	if err != nil {
-		return 0, 0, err
+		return
 	}
 	if r.buf[0] < utf8.RuneSelf { // fast check for common ASCII case
 		rr = rune(r.buf[0])
 		size = 1 // Known to be 1.
+		// Flip the bits of the rune so it's available to UnreadRune.
+		r.peekRune = ^rr
 		return
 	}
 	var n int
-	for n = 1; !utf8.FullRune(r.buf[0:n]); n++ {
+	for n = 1; !utf8.FullRune(r.buf[:n]); n++ {
 		r.buf[n], err = r.readByte()
 		if err != nil {
 			if err == io.EOF {
@@ -380,13 +363,25 @@ func (r *readRune) ReadRune() (rr rune, size int, err error) {
 			return
 		}
 	}
-	rr, size = utf8.DecodeRune(r.buf[0:n])
-	if size < n { // an error
-		r.unread(r.buf[size:n])
+	rr, size = utf8.DecodeRune(r.buf[:n])
+	if size < n { // an error, save the bytes for the next read
+		copy(r.pendBuf[r.pending:], r.buf[size:n])
+		r.pending += n - size
 	}
+	// Flip the bits of the rune so it's available to UnreadRune.
+	r.peekRune = ^rr
 	return
 }
 
+func (r *readRune) UnreadRune() error {
+	if r.peekRune >= 0 {
+		return errors.New("fmt: scanning called UnreadRune with no rune available")
+	}
+	// Reverse bit flip of previously read rune to obtain valid >=0 state.
+	r.peekRune = ^r.peekRune
+	return nil
+}
+
 var ssFree = sync.Pool{
 	New: func() interface{} { return new(ss) },
 }
@@ -394,15 +389,13 @@ var ssFree = sync.Pool{
 // newScanState allocates a new ss struct or grab a cached one.
 func newScanState(r io.Reader, nlIsSpace, nlIsEnd bool) (s *ss, old ssave) {
 	s = ssFree.Get().(*ss)
-	if rr, ok := r.(io.RuneReader); ok {
-		s.rr = rr
+	if rs, ok := r.(io.RuneScanner); ok {
+		s.rs = rs
 	} else {
-		s.rr = &readRune{reader: r}
+		s.rs = &readRune{reader: r, peekRune: -1}
 	}
 	s.nlIsSpace = nlIsSpace
 	s.nlIsEnd = nlIsEnd
-	s.prevRune = -1
-	s.peekRune = -1
 	s.atEOF = false
 	s.limit = hugeWid
 	s.argLimit = hugeWid
@@ -424,7 +417,7 @@ func (s *ss) free(old ssave) {
 		return
 	}
 	s.buf = s.buf[:0]
-	s.rr = nil
+	s.rs = nil
 	ssFree.Put(s)
 }
 
@@ -455,8 +448,8 @@ func (s *ss) skipSpace(stopAtNewline bool) {
 	}
 }
 
-// token returns the next space-delimited string from the input.  It
-// skips white space.  For Scanln, it stops at newlines.  For Scan,
+// token returns the next space-delimited string from the input. It
+// skips white space. For Scanln, it stops at newlines. For Scan,
 // newlines are treated as spaces.
 func (s *ss) token(skipSpace bool, f func(rune) bool) []byte {
 	if skipSpace {
@@ -525,7 +518,7 @@ func (s *ss) notEOF() {
 	s.UnreadRune()
 }
 
-// accept checks the next rune in the input.  If it's a byte (sic) in the string, it puts it in the
+// accept checks the next rune in the input. If it's a byte (sic) in the string, it puts it in the
 // buffer and returns true. Otherwise it return false.
 func (s *ss) accept(ok string) bool {
 	return s.consume(ok, true)
@@ -549,7 +542,7 @@ func (s *ss) scanBool(verb rune) bool {
 	if !s.okVerb(verb, "tv", "boolean") {
 		return false
 	}
-	// Syntax-checking a boolean is annoying.  We're not fastidious about case.
+	// Syntax-checking a boolean is annoying. We're not fastidious about case.
 	switch s.getRune() {
 	case '0':
 		return false
@@ -643,7 +636,7 @@ func (s *ss) scanBasePrefix() (base int, digits string, found bool) {
 }
 
 // scanInt returns the value of the integer represented by the next
-// token, checking for overflow.  Any error is stored in s.err.
+// token, checking for overflow. Any error is stored in s.err.
 func (s *ss) scanInt(verb rune, bitSize int) int64 {
 	if verb == 'c' {
 		return s.scanRune(bitSize)
@@ -676,7 +669,7 @@ func (s *ss) scanInt(verb rune, bitSize int) int64 {
 }
 
 // scanUint returns the value of the unsigned integer represented
-// by the next token, checking for overflow.  Any error is stored in s.err.
+// by the next token, checking for overflow. Any error is stored in s.err.
 func (s *ss) scanUint(verb rune, bitSize int) uint64 {
 	if verb == 'c' {
 		return uint64(s.scanRune(bitSize))
@@ -846,7 +839,7 @@ func (s *ss) quotedString() string {
 		return string(s.buf)
 	case '"':
 		// Double-quoted: Include the quotes and let strconv.Unquote do the backslash escapes.
-		s.buf.WriteRune(quote)
+		s.buf.WriteByte('"')
 		for {
 			r := s.mustReadRune()
 			s.buf.WriteRune(r)
@@ -922,9 +915,14 @@ func (s *ss) hexString() string {
 	return string(s.buf)
 }
 
-const floatVerbs = "beEfFgGv"
+const (
+	floatVerbs = "beEfFgGv"
 
-const hugeWid = 1 << 30
+	hugeWid = 1 << 30
+
+	intBits     = 32 << (^uint(0) >> 63)
+	uintptrBits = 32 << (^uintptr(0) >> 63)
+)
 
 // scanOne scans a single value, deriving the scanner from the type of the argument.
 func (s *ss) scanOne(verb rune, arg interface{}) {
@@ -1142,7 +1140,7 @@ func (s *ss) advance(format string) (i int) {
 }
 
 // doScanf does the real work when scanning with a format string.
-//  At the moment, it handles only pointers to basic types.
+// At the moment, it handles only pointers to basic types.
 func (s *ss) doScanf(format string, a []interface{}) (numProcessed int, err error) {
 	defer errorHandler(&err)
 	end := len(format) - 1
@@ -1155,7 +1153,7 @@ func (s *ss) doScanf(format string, a []interface{}) (numProcessed int, err erro
 		}
 		// Either we failed to advance, we have a percent character, or we ran out of input.
 		if format[i] != '%' {
-			// Can't advance format.  Why not?
+			// Can't advance format. Why not?
 			if w < 0 {
 				s.errorString("input does not match format")
 			}
diff --git a/libgo/go/fmt/scan_test.go b/libgo/go/fmt/scan_test.go
index 7ac74dcb4bd..e36b62e78a8 100644
--- a/libgo/go/fmt/scan_test.go
+++ b/libgo/go/fmt/scan_test.go
@@ -15,6 +15,7 @@ import (
 	"regexp"
 	"strings"
 	"testing"
+	"testing/iotest"
 	"unicode/utf8"
 )
 
@@ -78,12 +79,6 @@ var (
 	renamedComplex128Val renamedComplex128
 )
 
-type FloatTest struct {
-	text string
-	in   float64
-	out  float64
-}
-
 // Xs accepts any non-empty run of the verb character
 type Xs string
 
@@ -124,20 +119,6 @@ func (s *IntString) Scan(state ScanState, verb rune) error {
 
 var intStringVal IntString
 
-// myStringReader implements Read but not ReadRune, allowing us to test our readRune wrapper
-// type that creates something that can read runes given only Read().
-type myStringReader struct {
-	r *strings.Reader
-}
-
-func (s *myStringReader) Read(p []byte) (n int, err error) {
-	return s.r.Read(p)
-}
-
-func newReader(s string) *myStringReader {
-	return &myStringReader{strings.NewReader(s)}
-}
-
 var scanTests = []ScanTest{
 	// Basic types
 	{"T\n", &boolVal, true},  // boolean test vals toggle to be sure they are written
@@ -369,25 +350,38 @@ var multiTests = []ScanfMultiTest{
 	{"%v%v", "FALSE23", args(&truth, &i), args(false, 23), ""},
 }
 
-func testScan(name string, t *testing.T, scan func(r io.Reader, a ...interface{}) (int, error)) {
+var readers = []struct {
+	name string
+	f    func(string) io.Reader
+}{
+	{"StringReader", func(s string) io.Reader {
+		return strings.NewReader(s)
+	}},
+	{"ReaderOnly", func(s string) io.Reader {
+		return struct{ io.Reader }{strings.NewReader(s)}
+	}},
+	{"OneByteReader", func(s string) io.Reader {
+		return iotest.OneByteReader(strings.NewReader(s))
+	}},
+	{"DataErrReader", func(s string) io.Reader {
+		return iotest.DataErrReader(strings.NewReader(s))
+	}},
+}
+
+func testScan(t *testing.T, f func(string) io.Reader, scan func(r io.Reader, a ...interface{}) (int, error)) {
 	for _, test := range scanTests {
-		var r io.Reader
-		if name == "StringReader" {
-			r = strings.NewReader(test.text)
-		} else {
-			r = newReader(test.text)
-		}
+		r := f(test.text)
 		n, err := scan(r, test.in)
 		if err != nil {
 			m := ""
 			if n > 0 {
 				m = Sprintf(" (%d fields ok)", n)
 			}
-			t.Errorf("%s got error scanning %q: %s%s", name, test.text, err, m)
+			t.Errorf("got error scanning %q: %s%s", test.text, err, m)
 			continue
 		}
 		if n != 1 {
-			t.Errorf("%s count error on entry %q: got %d", name, test.text, n)
+			t.Errorf("count error on entry %q: got %d", test.text, n)
 			continue
 		}
 		// The incoming value may be a pointer
@@ -397,25 +391,25 @@ func testScan(name string, t *testing.T, scan func(r io.Reader, a ...interface{}
 		}
 		val := v.Interface()
 		if !reflect.DeepEqual(val, test.out) {
-			t.Errorf("%s scanning %q: expected %#v got %#v, type %T", name, test.text, test.out, val, val)
+			t.Errorf("scanning %q: expected %#v got %#v, type %T", test.text, test.out, val, val)
 		}
 	}
 }
 
 func TestScan(t *testing.T) {
-	testScan("StringReader", t, Fscan)
-}
-
-func TestMyReaderScan(t *testing.T) {
-	testScan("myStringReader", t, Fscan)
+	for _, r := range readers {
+		t.Run(r.name, func(t *testing.T) {
+			testScan(t, r.f, Fscan)
+		})
+	}
 }
 
 func TestScanln(t *testing.T) {
-	testScan("StringReader", t, Fscanln)
-}
-
-func TestMyReaderScanln(t *testing.T) {
-	testScan("myStringReader", t, Fscanln)
+	for _, r := range readers {
+		t.Run(r.name, func(t *testing.T) {
+			testScan(t, r.f, Fscanln)
+		})
+	}
 }
 
 func TestScanf(t *testing.T) {
@@ -506,20 +500,15 @@ func TestInf(t *testing.T) {
 	}
 }
 
-func testScanfMulti(name string, t *testing.T) {
+func testScanfMulti(t *testing.T, f func(string) io.Reader) {
 	sliceType := reflect.TypeOf(make([]interface{}, 1))
 	for _, test := range multiTests {
-		var r io.Reader
-		if name == "StringReader" {
-			r = strings.NewReader(test.text)
-		} else {
-			r = newReader(test.text)
-		}
+		r := f(test.text)
 		n, err := Fscanf(r, test.format, test.in...)
 		if err != nil {
 			if test.err == "" {
 				t.Errorf("got error scanning (%q, %q): %q", test.format, test.text, err)
-			} else if strings.Index(err.Error(), test.err) < 0 {
+			} else if !strings.Contains(err.Error(), test.err) {
 				t.Errorf("got wrong error scanning (%q, %q): %q; expected %q", test.format, test.text, err, test.err)
 			}
 			continue
@@ -545,11 +534,11 @@ func testScanfMulti(name string, t *testing.T) {
 }
 
 func TestScanfMulti(t *testing.T) {
-	testScanfMulti("StringReader", t)
-}
-
-func TestMyReaderScanfMulti(t *testing.T) {
-	testScanfMulti("myStringReader", t)
+	for _, r := range readers {
+		t.Run(r.name, func(t *testing.T) {
+			testScanfMulti(t, r.f)
+		})
+	}
 }
 
 func TestScanMultiple(t *testing.T) {
@@ -613,7 +602,7 @@ func TestScanNotPointer(t *testing.T) {
 	_, err := Fscan(r, a)
 	if err == nil {
 		t.Error("expected error scanning non-pointer")
-	} else if strings.Index(err.Error(), "pointer") < 0 {
+	} else if !strings.Contains(err.Error(), "pointer") {
 		t.Errorf("expected pointer error scanning non-pointer, got: %s", err)
 	}
 }
@@ -623,7 +612,7 @@ func TestScanlnNoNewline(t *testing.T) {
 	_, err := Sscanln("1 x\n", &a)
 	if err == nil {
 		t.Error("expected error scanning string missing newline")
-	} else if strings.Index(err.Error(), "newline") < 0 {
+	} else if !strings.Contains(err.Error(), "newline") {
 		t.Errorf("expected newline error scanning string missing newline, got: %s", err)
 	}
 }
@@ -634,7 +623,7 @@ func TestScanlnWithMiddleNewline(t *testing.T) {
 	_, err := Fscanln(r, &a, &b)
 	if err == nil {
 		t.Error("expected error scanning string with extra newline")
-	} else if strings.Index(err.Error(), "newline") < 0 {
+	} else if !strings.Contains(err.Error(), "newline") {
 		t.Errorf("expected newline error scanning string with extra newline, got: %s", err)
 	}
 }
@@ -767,7 +756,7 @@ func TestUnreadRuneWithBufio(t *testing.T) {
 
 type TwoLines string
 
-// Scan attempts to read two lines into the object.  Scanln should prevent this
+// Scan attempts to read two lines into the object. Scanln should prevent this
 // because it stops at newline; Scan and Scanf should be fine.
 func (t *TwoLines) Scan(state ScanState, verb rune) error {
 	chars := make([]rune, 0, 100)
@@ -824,20 +813,10 @@ func TestMultiLine(t *testing.T) {
 	}
 }
 
-// simpleReader is a strings.Reader that implements only Read, not ReadRune.
-// Good for testing readahead.
-type simpleReader struct {
-	sr *strings.Reader
-}
-
-func (s *simpleReader) Read(b []byte) (n int, err error) {
-	return s.sr.Read(b)
-}
-
 // TestLineByLineFscanf tests that Fscanf does not read past newline. Issue
 // 3481.
 func TestLineByLineFscanf(t *testing.T) {
-	r := &simpleReader{strings.NewReader("1\n2\n")}
+	r := struct{ io.Reader }{strings.NewReader("1\n2\n")}
 	var i, j int
 	n, err := Fscanf(r, "%v\n", &i)
 	if n != 1 || err != nil {
@@ -1001,6 +980,18 @@ func BenchmarkScanRecursiveInt(b *testing.B) {
 	}
 }
 
+func BenchmarkScanRecursiveIntReaderWrapper(b *testing.B) {
+	b.ResetTimer()
+	ints := makeInts(intCount)
+	var r RecursiveInt
+	for i := b.N - 1; i >= 0; i-- {
+		buf := struct{ io.Reader }{strings.NewReader(string(ints))}
+		b.StartTimer()
+		Fscan(buf, &r)
+		b.StopTimer()
+	}
+}
+
 // Issue 9124.
 // %x on bytes couldn't handle non-space bytes terminating the scan.
 func TestHexBytes(t *testing.T) {
diff --git a/libgo/go/go/ast/ast.go b/libgo/go/go/ast/ast.go
index 5ab4283826b..d3dcd7915ba 100644
--- a/libgo/go/go/ast/ast.go
+++ b/libgo/go/go/ast/ast.go
@@ -99,7 +99,7 @@ func (g *CommentGroup) Text() string {
 	}
 	comments := make([]string, len(g.List))
 	for i, c := range g.List {
-		comments[i] = string(c.Text)
+		comments[i] = c.Text
 	}
 
 	lines := make([]string, 0, 10) // most comments are less than 10 lines
@@ -418,7 +418,7 @@ type (
 )
 
 // Pos and End implementations for expression/type nodes.
-//
+
 func (x *BadExpr) Pos() token.Pos  { return x.From }
 func (x *Ident) Pos() token.Pos    { return x.NamePos }
 func (x *Ellipsis) Pos() token.Pos { return x.Ellipsis }
@@ -709,7 +709,7 @@ type (
 )
 
 // Pos and End implementations for statement nodes.
-//
+
 func (s *BadStmt) Pos() token.Pos        { return s.From }
 func (s *DeclStmt) Pos() token.Pos       { return s.Decl.Pos() }
 func (s *EmptyStmt) Pos() token.Pos      { return s.Semicolon }
@@ -854,7 +854,7 @@ type (
 )
 
 // Pos and End implementations for spec nodes.
-//
+
 func (s *ImportSpec) Pos() token.Pos {
 	if s.Name != nil {
 		return s.Name.Pos()
@@ -931,7 +931,7 @@ type (
 )
 
 // Pos and End implementations for declaration nodes.
-//
+
 func (d *BadDecl) Pos() token.Pos  { return d.From }
 func (d *GenDecl) Pos() token.Pos  { return d.TokPos }
 func (d *FuncDecl) Pos() token.Pos { return d.Type.Pos() }
diff --git a/libgo/go/go/ast/commentmap.go b/libgo/go/go/ast/commentmap.go
index ac999d627ce..2a653a60ac9 100644
--- a/libgo/go/go/ast/commentmap.go
+++ b/libgo/go/go/ast/commentmap.go
@@ -267,7 +267,7 @@ func (cmap CommentMap) Filter(node Node) CommentMap {
 }
 
 // Comments returns the list of comment groups in the comment map.
-// The result is sorted is source order.
+// The result is sorted in source order.
 //
 func (cmap CommentMap) Comments() []*CommentGroup {
 	list := make([]*CommentGroup, 0, len(cmap))
diff --git a/libgo/go/go/ast/import.go b/libgo/go/go/ast/import.go
index 5c794c3e798..6b27fe822e5 100644
--- a/libgo/go/go/ast/import.go
+++ b/libgo/go/go/ast/import.go
@@ -31,7 +31,7 @@ func SortImports(fset *token.FileSet, f *File) {
 		specs := d.Specs[:0]
 		for j, s := range d.Specs {
 			if j > i && fset.Position(s.Pos()).Line > 1+fset.Position(d.Specs[j-1].End()).Line {
-				// j begins a new run.  End this one.
+				// j begins a new run. End this one.
 				specs = append(specs, sortSpecs(fset, f, d.Specs[i:j])...)
 				i = j
 			}
diff --git a/libgo/go/go/ast/print.go b/libgo/go/go/ast/print.go
index f15dc11dc05..d86d9ba64b7 100644
--- a/libgo/go/go/ast/print.go
+++ b/libgo/go/go/ast/print.go
@@ -36,8 +36,11 @@ func NotNilFilter(_ string, v reflect.Value) bool {
 // struct fields for which f(fieldname, fieldvalue) is true are
 // printed; all others are filtered from the output. Unexported
 // struct fields are never printed.
-//
-func Fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) (err error) {
+func Fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) error {
+	return fprint(w, fset, x, f)
+}
+
+func fprint(w io.Writer, fset *token.FileSet, x interface{}, f FieldFilter) (err error) {
 	// setup printer
 	p := printer{
 		output: w,
diff --git a/libgo/go/go/ast/resolve.go b/libgo/go/go/ast/resolve.go
index 0406bfc584a..c1830b5e4db 100644
--- a/libgo/go/go/ast/resolve.go
+++ b/libgo/go/go/ast/resolve.go
@@ -56,7 +56,7 @@ func resolve(scope *Scope, ident *Ident) bool {
 // indexed by package id (canonical import path).
 // An Importer must determine the canonical import path and
 // check the map to see if it is already present in the imports map.
-// If so, the Importer can return the map entry.  Otherwise, the
+// If so, the Importer can return the map entry. Otherwise, the
 // Importer should load the package data for the given path into
 // a new *Object (pkg), record pkg in the imports map, and then
 // return pkg.
diff --git a/libgo/go/go/build/build.go b/libgo/go/go/build/build.go
index 2f570c334dc..78e95c14880 100644
--- a/libgo/go/go/build/build.go
+++ b/libgo/go/go/build/build.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -55,8 +55,8 @@ type Context struct {
 	InstallSuffix string
 
 	// By default, Import uses the operating system's file system calls
-	// to read directories and files.  To read from other sources,
-	// callers can set the following functions.  They all have default
+	// to read directories and files. To read from other sources,
+	// callers can set the following functions. They all have default
 	// behaviors that use the local file system, so clients need only set
 	// the functions whose behaviors they wish to change.
 
@@ -87,11 +87,11 @@ type Context struct {
 	// ReadDir returns a slice of os.FileInfo, sorted by Name,
 	// describing the content of the named directory.
 	// If ReadDir is nil, Import uses ioutil.ReadDir.
-	ReadDir func(dir string) (fi []os.FileInfo, err error)
+	ReadDir func(dir string) ([]os.FileInfo, error)
 
 	// OpenFile opens a file (not a directory) for reading.
 	// If OpenFile is nil, Import uses os.Open.
-	OpenFile func(path string) (r io.ReadCloser, err error)
+	OpenFile func(path string) (io.ReadCloser, error)
 }
 
 // joinPath calls ctxt.JoinPath (if not nil) or else filepath.Join.
@@ -303,7 +303,7 @@ func defaultContext() Context {
 	// in all releases >= Go 1.x. Code that requires Go 1.x or later should
 	// say "+build go1.x", and code that should only be built before Go 1.x
 	// (perhaps it is the stub to use in that case) should say "+build !go1.x".
-	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4", "go1.5", "go1.6"}
+	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4", "go1.5", "go1.6", "go1.7"}
 
 	switch os.Getenv("CGO_ENABLED") {
 	case "1":
@@ -335,12 +335,19 @@ type ImportMode uint
 
 const (
 	// If FindOnly is set, Import stops after locating the directory
-	// that should contain the sources for a package.  It does not
+	// that should contain the sources for a package. It does not
 	// read any files in the directory.
 	FindOnly ImportMode = 1 << iota
 
 	// If AllowBinary is set, Import can be satisfied by a compiled
 	// package object without corresponding sources.
+	//
+	// Deprecated:
+	// The supported way to create a compiled-only package is to
+	// write source code containing a //go:binary-only-package comment at
+	// the top of the file. Such a package will be recognized
+	// regardless of this flag setting (because it has source code)
+	// and will have BinaryOnly set to true in the returned Package.
 	AllowBinary
 
 	// If ImportComment is set, parse import comments on package statements.
@@ -381,6 +388,7 @@ type Package struct {
 	PkgObj        string   // installed .a file
 	AllTags       []string // tags that can influence file selection in this directory
 	ConflictDir   string   // this directory shadows Dir in $GOPATH
+	BinaryOnly    bool     // cannot be rebuilt from source (has //go:binary-only-package comment)
 
 	// Source files
 	GoFiles        []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
@@ -391,6 +399,7 @@ type Package struct {
 	CXXFiles       []string // .cc, .cpp and .cxx source files
 	MFiles         []string // .m (Objective-C) source files
 	HFiles         []string // .h, .hh, .hpp and .hxx source files
+	FFiles         []string // .f, .F, .for and .f90 Fortran source files
 	SFiles         []string // .s source files
 	SwigFiles      []string // .swig files
 	SwigCXXFiles   []string // .swigcxx files
@@ -400,6 +409,7 @@ type Package struct {
 	CgoCFLAGS    []string // Cgo CFLAGS directives
 	CgoCPPFLAGS  []string // Cgo CPPFLAGS directives
 	CgoCXXFLAGS  []string // Cgo CXXFLAGS directives
+	CgoFFLAGS    []string // Cgo FFLAGS directives
 	CgoLDFLAGS   []string // Cgo LDFLAGS directives
 	CgoPkgConfig []string // Cgo pkg-config directives
 
@@ -710,7 +720,7 @@ Found:
 			p.InvalidGoFiles = append(p.InvalidGoFiles, name)
 		}
 
-		match, data, filename, err := ctxt.matchFile(p.Dir, name, true, allTags)
+		match, data, filename, err := ctxt.matchFile(p.Dir, name, true, allTags, &p.BinaryOnly)
 		if err != nil {
 			badFile(err)
 			continue
@@ -722,7 +732,7 @@ Found:
 			continue
 		}
 
-		// Going to save the file.  For non-Go files, can stop here.
+		// Going to save the file. For non-Go files, can stop here.
 		switch ext {
 		case ".c":
 			p.CFiles = append(p.CFiles, name)
@@ -736,6 +746,9 @@ Found:
 		case ".h", ".hh", ".hpp", ".hxx":
 			p.HFiles = append(p.HFiles, name)
 			continue
+		case ".f", ".F", ".for", ".f90":
+			p.FFiles = append(p.FFiles, name)
+			continue
 		case ".s":
 			p.SFiles = append(p.SFiles, name)
 			continue
@@ -1021,7 +1034,7 @@ func parseWord(data []byte) (word, rest []byte) {
 // MatchFile considers the name of the file and may use ctxt.OpenFile to
 // read some or all of the file's content.
 func (ctxt *Context) MatchFile(dir, name string) (match bool, err error) {
-	match, _, _, err = ctxt.matchFile(dir, name, false, nil)
+	match, _, _, err = ctxt.matchFile(dir, name, false, nil, nil)
 	return
 }
 
@@ -1033,7 +1046,7 @@ func (ctxt *Context) MatchFile(dir, name string) (match bool, err error) {
 // considers text until the first non-comment.
 // If allTags is non-nil, matchFile records any encountered build tag
 // by setting allTags[tag] = true.
-func (ctxt *Context) matchFile(dir, name string, returnImports bool, allTags map[string]bool) (match bool, data []byte, filename string, err error) {
+func (ctxt *Context) matchFile(dir, name string, returnImports bool, allTags map[string]bool, binaryOnly *bool) (match bool, data []byte, filename string, err error) {
 	if strings.HasPrefix(name, "_") ||
 		strings.HasPrefix(name, ".") {
 		return
@@ -1050,7 +1063,7 @@ func (ctxt *Context) matchFile(dir, name string, returnImports bool, allTags map
 	}
 
 	switch ext {
-	case ".go", ".c", ".cc", ".cxx", ".cpp", ".m", ".s", ".h", ".hh", ".hpp", ".hxx", ".S", ".swig", ".swigcxx":
+	case ".go", ".c", ".cc", ".cxx", ".cpp", ".m", ".s", ".h", ".hh", ".hpp", ".hxx", ".f", ".F", ".f90", ".S", ".swig", ".swigcxx":
 		// tentatively okay - read to make sure
 	case ".syso":
 		// binary, no reading
@@ -1069,7 +1082,11 @@ func (ctxt *Context) matchFile(dir, name string, returnImports bool, allTags map
 
 	if strings.HasSuffix(filename, ".go") {
 		data, err = readImports(f, false, nil)
+		if strings.HasSuffix(filename, "_test.go") {
+			binaryOnly = nil // ignore //go:binary-only-package comments in _test.go files
+		}
 	} else {
+		binaryOnly = nil // ignore //go:binary-only-package comments in non-Go sources
 		data, err = readComments(f)
 	}
 	f.Close()
@@ -1079,7 +1096,7 @@ func (ctxt *Context) matchFile(dir, name string, returnImports bool, allTags map
 	}
 
 	// Look for +build comments to accept or reject the file.
-	if !ctxt.shouldBuild(data, allTags) && !ctxt.UseAllFiles {
+	if !ctxt.shouldBuild(data, allTags, binaryOnly) && !ctxt.UseAllFiles {
 		return
 	}
 
@@ -1108,6 +1125,11 @@ func ImportDir(dir string, mode ImportMode) (*Package, error) {
 
 var slashslash = []byte("//")
 
+// Special comment denoting a binary-only package.
+// See https://golang.org/design/2775-binary-only-packages
+// for more about the design of binary-only packages.
+var binaryOnlyComment = []byte("//go:binary-only-package")
+
 // shouldBuild reports whether it is okay to use this file,
 // The rule is that in the file's leading run of // comments
 // and blank lines, which must be followed by a blank line
@@ -1115,13 +1137,19 @@ var slashslash = []byte("//")
 // lines beginning with '// +build' are taken as build directives.
 //
 // The file is accepted only if each such line lists something
-// matching the file.  For example:
+// matching the file. For example:
 //
 //	// +build windows linux
 //
 // marks the file as applicable only on Windows and Linux.
 //
-func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool) bool {
+// If shouldBuild finds a //go:binary-only-package comment in a file that
+// should be built, it sets *binaryOnly to true. Otherwise it does
+// not change *binaryOnly.
+//
+func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool, binaryOnly *bool) bool {
+	sawBinaryOnly := false
+
 	// Pass 1. Identify leading run of // comments and blank lines,
 	// which must be followed by a blank line.
 	end := 0
@@ -1156,6 +1184,9 @@ func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool) bool {
 		}
 		line = bytes.TrimSpace(line)
 		if bytes.HasPrefix(line, slashslash) {
+			if bytes.Equal(line, binaryOnlyComment) {
+				sawBinaryOnly = true
+			}
 			line = bytes.TrimSpace(line[len(slashslash):])
 			if len(line) > 0 && line[0] == '+' {
 				// Looks like a comment +line.
@@ -1175,6 +1206,10 @@ func (ctxt *Context) shouldBuild(content []byte, allTags map[string]bool) bool {
 		}
 	}
 
+	if binaryOnly != nil && sawBinaryOnly {
+		*binaryOnly = true
+	}
+
 	return allok
 }
 
@@ -1241,6 +1276,8 @@ func (ctxt *Context) saveCgo(filename string, di *Package, cg *ast.CommentGroup)
 			di.CgoCPPFLAGS = append(di.CgoCPPFLAGS, args...)
 		case "CXXFLAGS":
 			di.CgoCXXFLAGS = append(di.CgoCXXFLAGS, args...)
+		case "FFLAGS":
+			di.CgoFFLAGS = append(di.CgoFFLAGS, args...)
 		case "LDFLAGS":
 			di.CgoLDFLAGS = append(di.CgoLDFLAGS, args...)
 		case "pkg-config":
@@ -1256,7 +1293,7 @@ func (ctxt *Context) saveCgo(filename string, di *Package, cg *ast.CommentGroup)
 // the result is safe for the shell.
 func expandSrcDir(str string, srcdir string) (string, bool) {
 	// "\" delimited paths cause safeCgoName to fail
-	// so convert native paths with a different delimeter
+	// so convert native paths with a different delimiter
 	// to "/" before starting (eg: on windows).
 	srcdir = filepath.ToSlash(srcdir)
 
@@ -1292,7 +1329,7 @@ func safeCgoName(s string, spaces bool) bool {
 		safe = safe[len(safeSpaces):]
 	}
 	for i := 0; i < len(s); i++ {
-		if c := s[i]; c < 0x80 && bytes.IndexByte(safe, c) < 0 {
+		if c := s[i]; c < utf8.RuneSelf && bytes.IndexByte(safe, c) < 0 {
 			return false
 		}
 	}
@@ -1305,7 +1342,7 @@ func safeCgoName(s string, spaces bool) bool {
 // Single quotes and double quotes are recognized to prevent splitting within the
 // quoted region, and are removed from the resulting substrings. If a quote in s
 // isn't closed err will be set and r will have the unclosed argument as the
-// last element.  The backslash is used for escaping.
+// last element. The backslash is used for escaping.
 //
 // For example, the following string:
 //
diff --git a/libgo/go/go/build/build_test.go b/libgo/go/go/build/build_test.go
index 4d705b6fb28..9f3c83258c7 100644
--- a/libgo/go/go/build/build_test.go
+++ b/libgo/go/go/build/build_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -152,28 +152,28 @@ func TestShouldBuild(t *testing.T) {
 
 	ctx := &Context{BuildTags: []string{"tag1"}}
 	m := map[string]bool{}
-	if !ctx.shouldBuild([]byte(file1), m) {
+	if !ctx.shouldBuild([]byte(file1), m, nil) {
 		t.Errorf("shouldBuild(file1) = false, want true")
 	}
 	if !reflect.DeepEqual(m, want1) {
-		t.Errorf("shoudBuild(file1) tags = %v, want %v", m, want1)
+		t.Errorf("shouldBuild(file1) tags = %v, want %v", m, want1)
 	}
 
 	m = map[string]bool{}
-	if ctx.shouldBuild([]byte(file2), m) {
-		t.Errorf("shouldBuild(file2) = true, want fakse")
+	if ctx.shouldBuild([]byte(file2), m, nil) {
+		t.Errorf("shouldBuild(file2) = true, want false")
 	}
 	if !reflect.DeepEqual(m, want2) {
-		t.Errorf("shoudBuild(file2) tags = %v, want %v", m, want2)
+		t.Errorf("shouldBuild(file2) tags = %v, want %v", m, want2)
 	}
 
 	m = map[string]bool{}
 	ctx = &Context{BuildTags: nil}
-	if !ctx.shouldBuild([]byte(file3), m) {
+	if !ctx.shouldBuild([]byte(file3), m, nil) {
 		t.Errorf("shouldBuild(file3) = false, want true")
 	}
 	if !reflect.DeepEqual(m, want3) {
-		t.Errorf("shoudBuild(file3) tags = %v, want %v", m, want3)
+		t.Errorf("shouldBuild(file3) tags = %v, want %v", m, want3)
 	}
 }
 
@@ -302,15 +302,14 @@ func TestShellSafety(t *testing.T) {
 }
 
 func TestImportVendor(t *testing.T) {
-	t.Skip("skipping; hpack has moved to internal for now; golang.org/issue/14047")
 	testenv.MustHaveGoBuild(t) // really must just have source
 	ctxt := Default
 	ctxt.GOPATH = ""
-	p, err := ctxt.Import("golang.org/x/net/http2/hpack", filepath.Join(ctxt.GOROOT, "src/net/http"), 0)
+	p, err := ctxt.Import("golang_org/x/net/http2/hpack", filepath.Join(ctxt.GOROOT, "src/net/http"), 0)
 	if err != nil {
-		t.Fatalf("cannot find vendored golang.org/x/net/http2/hpack from net/http directory: %v", err)
+		t.Fatalf("cannot find vendored golang_org/x/net/http2/hpack from net/http directory: %v", err)
 	}
-	want := "vendor/golang.org/x/net/http2/hpack"
+	want := "vendor/golang_org/x/net/http2/hpack"
 	if p.ImportPath != want {
 		t.Fatalf("Import succeeded but found %q, want %q", p.ImportPath, want)
 	}
@@ -336,7 +335,7 @@ func TestImportVendorParentFailure(t *testing.T) {
 	ctxt := Default
 	ctxt.GOPATH = ""
 	// This import should fail because the vendor/golang.org/x/net/http2 directory has no source code.
-	p, err := ctxt.Import("golang.org/x/net/http2", filepath.Join(ctxt.GOROOT, "src/net/http"), 0)
+	p, err := ctxt.Import("golang_org/x/net/http2", filepath.Join(ctxt.GOROOT, "src/net/http"), 0)
 	if err == nil {
 		t.Fatalf("found empty parent in %s", p.Dir)
 	}
diff --git a/libgo/go/go/build/deps_test.go b/libgo/go/go/build/deps_test.go
index c7cd8804da7..5b2529129cc 100644
--- a/libgo/go/go/build/deps_test.go
+++ b/libgo/go/go/build/deps_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -21,7 +21,7 @@ import (
 )
 
 // pkgDeps defines the expected dependencies between packages in
-// the Go source tree.  It is a statement of policy.
+// the Go source tree. It is a statement of policy.
 // Changes should not be made to this map without prior discussion.
 //
 // The map contains two kinds of entries:
@@ -136,11 +136,23 @@ var pkgDeps = map[string][]string{
 	"internal/syscall/unix":             {"L0", "syscall"},
 	"internal/syscall/windows":          {"L0", "syscall", "internal/syscall/windows/sysdll"},
 	"internal/syscall/windows/registry": {"L0", "syscall", "internal/syscall/windows/sysdll", "unicode/utf16"},
-	"time":          {"L0", "syscall", "internal/syscall/windows/registry"},
+	"time": {
+		// "L0" without the "io" package:
+		"errors",
+		"runtime",
+		"runtime/internal/atomic",
+		"sync",
+		"sync/atomic",
+		"unsafe",
+		// Other time dependencies:
+		"internal/syscall/windows/registry",
+		"syscall",
+	},
+
 	"os":            {"L1", "os", "syscall", "time", "internal/syscall/windows"},
 	"path/filepath": {"L2", "os", "syscall"},
 	"io/ioutil":     {"L2", "os", "path/filepath", "time"},
-	"os/exec":       {"L2", "os", "path/filepath", "syscall"},
+	"os/exec":       {"L2", "os", "context", "path/filepath", "syscall"},
 	"os/signal":     {"L2", "os", "syscall"},
 
 	// OS enables basic operating system functionality,
@@ -161,14 +173,14 @@ var pkgDeps = map[string][]string{
 	"regexp":         {"L2", "regexp/syntax"},
 	"regexp/syntax":  {"L2"},
 	"runtime/debug":  {"L2", "fmt", "io/ioutil", "os", "time"},
-	"runtime/pprof":  {"L2", "fmt", "text/tabwriter"},
+	"runtime/pprof":  {"L2", "fmt", "os", "text/tabwriter"},
 	"runtime/trace":  {"L0"},
 	"text/tabwriter": {"L2"},
 
 	"testing":          {"L2", "flag", "fmt", "os", "runtime/debug", "runtime/pprof", "runtime/trace", "time"},
 	"testing/iotest":   {"L2", "log"},
 	"testing/quick":    {"L2", "flag", "fmt", "reflect"},
-	"internal/testenv": {"L2", "os", "testing"},
+	"internal/testenv": {"L2", "OS", "flag", "testing"},
 
 	// L4 is defined as L3+fmt+log+time, because in general once
 	// you're using L3 packages, use of fmt, log, or time is not a big deal.
@@ -215,6 +227,7 @@ var pkgDeps = map[string][]string{
 	"compress/gzip":            {"L4", "compress/flate"},
 	"compress/lzw":             {"L4"},
 	"compress/zlib":            {"L4", "compress/flate"},
+	"context":                  {"errors", "fmt", "reflect", "sync", "time"},
 	"database/sql":             {"L4", "container/list", "database/sql/driver"},
 	"database/sql/driver":      {"L4", "time"},
 	"debug/dwarf":              {"L4"},
@@ -279,7 +292,13 @@ var pkgDeps = map[string][]string{
 	// Basic networking.
 	// Because net must be used by any package that wants to
 	// do networking portably, it must have a small dependency set: just L0+basic os.
-	"net": {"L0", "CGO", "math/rand", "os", "sort", "syscall", "time", "internal/syscall/windows", "internal/singleflight", "internal/race"},
+	"net": {
+		"L0", "CGO",
+		"context", "math/rand", "os", "sort", "syscall", "time",
+		"internal/nettrace",
+		"internal/syscall/windows", "internal/singleflight", "internal/race",
+		"golang_org/x/net/route",
+	},
 
 	// NET enables use of basic network-related packages.
 	"NET": {
@@ -356,11 +375,16 @@ var pkgDeps = map[string][]string{
 	// HTTP, kingpin of dependencies.
 	"net/http": {
 		"L4", "NET", "OS",
-		"compress/gzip", "crypto/tls", "mime/multipart", "runtime/debug",
+		"context", "compress/gzip", "container/list", "crypto/tls",
+		"mime/multipart", "runtime/debug",
 		"net/http/internal",
-		"internal/golang.org/x/net/http2/hpack",
+		"golang_org/x/net/http2/hpack",
+		"golang_org/x/net/lex/httplex",
+		"internal/nettrace",
+		"net/http/httptrace",
 	},
-	"net/http/internal": {"L4"},
+	"net/http/internal":  {"L4"},
+	"net/http/httptrace": {"context", "internal/nettrace", "net", "reflect", "time"},
 
 	// HTTP-using packages.
 	"expvar":             {"L4", "OS", "encoding/json", "net/http"},
@@ -402,21 +426,6 @@ func allowed(pkg string) map[string]bool {
 	return m
 }
 
-var bools = []bool{false, true}
-var geese = []string{"android", "darwin", "dragonfly", "freebsd", "linux", "nacl", "netbsd", "openbsd", "plan9", "solaris", "windows"}
-var goarches = []string{"386", "amd64", "arm", "arm64"}
-
-type osPkg struct {
-	goos, pkg string
-}
-
-// allowedErrors are the operating systems and packages known to contain errors
-// (currently just "no Go source files")
-var allowedErrors = map[osPkg]bool{
-	osPkg{"windows", "log/syslog"}: true,
-	osPkg{"plan9", "log/syslog"}:   true,
-}
-
 // listStdPkgs returns the same list of packages as "go list std".
 func listStdPkgs(goroot string) ([]string, error) {
 	// Based on cmd/go's matchPackages function.
@@ -434,7 +443,7 @@ func listStdPkgs(goroot string) ([]string, error) {
 		}
 
 		name := filepath.ToSlash(path[len(src):])
-		if name == "builtin" || name == "cmd" || strings.Contains(name, ".") {
+		if name == "builtin" || name == "cmd" || strings.Contains(name, "golang_org") {
 			return filepath.SkipDir
 		}
 
diff --git a/libgo/go/go/build/doc.go b/libgo/go/go/build/doc.go
index d436d28b317..9f7ac8f8ac4 100644
--- a/libgo/go/go/build/doc.go
+++ b/libgo/go/go/build/doc.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,7 +8,7 @@
 //
 // The Go path is a list of directory trees containing Go source code.
 // It is consulted to resolve imports that cannot be found in the standard
-// Go tree.  The default path is the value of the GOPATH environment
+// Go tree. The default path is the value of the GOPATH environment
 // variable, interpreted as a path list appropriate to the operating system
 // (on Unix, the variable is a colon-separated string;
 // on Windows, a semicolon-separated string;
@@ -16,7 +16,7 @@
 //
 // Each directory listed in the Go path must have a prescribed structure:
 //
-// The src/ directory holds source code.  The path below 'src' determines
+// The src/ directory holds source code. The path below 'src' determines
 // the import path or executable name.
 //
 // The pkg/ directory holds installed package objects.
@@ -31,9 +31,9 @@
 //
 // The bin/ directory holds compiled commands.
 // Each command is named for its source directory, but only
-// using the final element, not the entire path.  That is, the
+// using the final element, not the entire path. That is, the
 // command with source in DIR/src/foo/quux is installed into
-// DIR/bin/quux, not DIR/bin/foo/quux.  The foo/ is stripped
+// DIR/bin/quux, not DIR/bin/foo/quux. The foo/ is stripped
 // so that you can add DIR/bin to your PATH to get at the
 // installed commands.
 //
@@ -103,6 +103,7 @@
 //	- "go1.4", from Go version 1.4 onward
 //	- "go1.5", from Go version 1.5 onward
 //	- "go1.6", from Go version 1.6 onward
+//	- "go1.7", from Go version 1.7 onward
 //	- any additional words listed in ctxt.BuildTags
 //
 // If a file's name, after stripping the extension and a possible _test suffix,
@@ -138,4 +139,26 @@
 // Using GOOS=android matches build tags and files as for GOOS=linux
 // in addition to android tags and files.
 //
+// Binary-Only Packages
+//
+// It is possible to distribute packages in binary form without including the
+// source code used for compiling the package. To do this, the package must
+// be distributed with a source file not excluded by build constraints and
+// containing a "//go:binary-only-package" comment.
+// Like a build constraint, this comment must appear near the top of the file,
+// preceded only by blank lines and other line comments and with a blank line
+// following the comment, to separate it from the package documentation.
+// Unlike build constraints, this comment is only recognized in non-test
+// Go source files.
+//
+// The minimal source code for a binary-only package is therefore:
+//
+//	//go:binary-only-package
+//
+//	package mypkg
+//
+// The source code may include additional Go code. That code is never compiled
+// but will be processed by tools like godoc and might be useful as end-user
+// documentation.
+//
 package build
diff --git a/libgo/go/go/build/read.go b/libgo/go/go/build/read.go
index 1049ac50d94..29b8cdc7867 100644
--- a/libgo/go/go/build/read.go
+++ b/libgo/go/go/build/read.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,6 +8,7 @@ import (
 	"bufio"
 	"errors"
 	"io"
+	"unicode/utf8"
 )
 
 type importReader struct {
@@ -20,7 +21,7 @@ type importReader struct {
 }
 
 func isIdent(c byte) bool {
-	return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '_' || c >= 0x80
+	return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '_' || c >= utf8.RuneSelf
 }
 
 var (
diff --git a/libgo/go/go/build/read_test.go b/libgo/go/go/build/read_test.go
index 326960bdc91..9cef657e13f 100644
--- a/libgo/go/go/build/read_test.go
+++ b/libgo/go/go/build/read_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/go/build/syslist.go b/libgo/go/go/build/syslist.go
index d800a78f0a1..60c9fbcb74f 100644
--- a/libgo/go/go/build/syslist.go
+++ b/libgo/go/go/build/syslist.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/go/build/syslist_test.go b/libgo/go/go/build/syslist_test.go
index 3be2928f525..7973ff4ee5f 100644
--- a/libgo/go/go/build/syslist_test.go
+++ b/libgo/go/go/build/syslist_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/go/constant/value.go b/libgo/go/go/constant/value.go
index 310814df71c..ab10ae32998 100644
--- a/libgo/go/go/constant/value.go
+++ b/libgo/go/go/constant/value.go
@@ -276,10 +276,10 @@ func smallRat(x *big.Float) bool {
 // MakeUnknown returns the Unknown value.
 func MakeUnknown() Value { return unknownVal{} }
 
-// MakeBool returns the Bool value for x.
+// MakeBool returns the Bool value for b.
 func MakeBool(b bool) Value { return boolVal(b) }
 
-// MakeString returns the String value for x.
+// MakeString returns the String value for s.
 func MakeString(s string) Value { return stringVal(s) }
 
 // MakeInt64 returns the Int value for x.
@@ -308,8 +308,8 @@ func MakeFloat64(x float64) Value {
 
 // MakeFromLiteral returns the corresponding integer, floating-point,
 // imaginary, character, or string value for a Go literal string. The
-// tok value must be one of token.INT, token.FLOAT, toke.IMAG, token.
-// CHAR, or token.STRING. The final argument must be zero.
+// tok value must be one of token.INT, token.FLOAT, token.IMAG,
+// token.CHAR, or token.STRING. The final argument must be zero.
 // If the literal string syntax is invalid, the result is an Unknown.
 func MakeFromLiteral(lit string, tok token.Token, zero uint) Value {
 	if zero != 0 {
diff --git a/libgo/go/go/constant/value_test.go b/libgo/go/go/constant/value_test.go
index dbd96c07a31..8a8a08eaaa1 100644
--- a/libgo/go/go/constant/value_test.go
+++ b/libgo/go/go/constant/value_test.go
@@ -244,6 +244,7 @@ var stringTests = []struct {
 	{"1e9999", "1e+9999", "0x.f8d4a9da224650a8cb2959e10d985ad92adbd44c62917e608b1f24c0e1b76b6f61edffeb15c135a4b601637315f7662f325f82325422b244286a07663c9415d2p+33216"},
 	{"1e-9999", "1e-9999", "0x.83b01ba6d8c0425eec1b21e96f7742d63c2653ed0a024cf8a2f9686df578d7b07d7a83d84df6a2ec70a921d1f6cd5574893a7eda4d28ee719e13a5dce2700759p-33215"},
 	{"2.71828182845904523536028747135266249775724709369995957496696763", "2.71828", "271828182845904523536028747135266249775724709369995957496696763/100000000000000000000000000000000000000000000000000000000000000"},
+	{"0e9999999999", "0", "0"}, // issue #16176
 
 	// Complex
 	{"0i", "(0 + 0i)", "(0 + 0i)"},
diff --git a/libgo/go/go/doc/comment.go b/libgo/go/go/doc/comment.go
index f414ca4090e..ed8eef4c61f 100644
--- a/libgo/go/go/doc/comment.go
+++ b/libgo/go/go/doc/comment.go
@@ -225,7 +225,7 @@ func heading(line string) string {
 	}
 
 	// exclude lines with illegal characters
-	if strings.IndexAny(line, ",.;:!?+*/=()[]{}_^°&§~%#@<\">\\") >= 0 {
+	if strings.ContainsAny(line, ",.;:!?+*/=()[]{}_^°&§~%#@<\">\\") {
 		return ""
 	}
 
@@ -398,7 +398,7 @@ func blocks(text string) []block {
 
 // ToText prepares comment text for presentation in textual output.
 // It wraps paragraphs of text to width or fewer Unicode code points
-// and then prefixes each line with the indent.  In preformatted sections
+// and then prefixes each line with the indent. In preformatted sections
 // (such as program text), it prefixes each non-blank line with preIndent.
 func ToText(w io.Writer, text string, indent, preIndent string, width int) {
 	l := lineWrapper{
diff --git a/libgo/go/go/doc/example.go b/libgo/go/go/doc/example.go
index c414e548ccd..bbf8096ce29 100644
--- a/libgo/go/go/doc/example.go
+++ b/libgo/go/go/doc/example.go
@@ -26,8 +26,9 @@ type Example struct {
 	Play        *ast.File // a whole program version of the example
 	Comments    []*ast.CommentGroup
 	Output      string // expected output
-	EmptyOutput bool   // expect empty output
-	Order       int    // original source code order
+	Unordered   bool
+	EmptyOutput bool // expect empty output
+	Order       int  // original source code order
 }
 
 // Examples returns the examples found in the files, sorted by Name field.
@@ -71,7 +72,7 @@ func Examples(files ...*ast.File) []*Example {
 			if f.Doc != nil {
 				doc = f.Doc.Text()
 			}
-			output, hasOutput := exampleOutput(f.Body, file.Comments)
+			output, unordered, hasOutput := exampleOutput(f.Body, file.Comments)
 			flist = append(flist, &Example{
 				Name:        name[len("Example"):],
 				Doc:         doc,
@@ -79,6 +80,7 @@ func Examples(files ...*ast.File) []*Example {
 				Play:        playExample(file, f.Body),
 				Comments:    file.Comments,
 				Output:      output,
+				Unordered:   unordered,
 				EmptyOutput: output == "" && hasOutput,
 				Order:       len(flist),
 			})
@@ -96,24 +98,27 @@ func Examples(files ...*ast.File) []*Example {
 	return list
 }
 
-var outputPrefix = regexp.MustCompile(`(?i)^[[:space:]]*output:`)
+var outputPrefix = regexp.MustCompile(`(?i)^[[:space:]]*(unordered )?output:`)
 
 // Extracts the expected output and whether there was a valid output comment
-func exampleOutput(b *ast.BlockStmt, comments []*ast.CommentGroup) (output string, ok bool) {
+func exampleOutput(b *ast.BlockStmt, comments []*ast.CommentGroup) (output string, unordered, ok bool) {
 	if _, last := lastComment(b, comments); last != nil {
 		// test that it begins with the correct prefix
 		text := last.Text()
-		if loc := outputPrefix.FindStringIndex(text); loc != nil {
+		if loc := outputPrefix.FindStringSubmatchIndex(text); loc != nil {
+			if loc[2] != -1 {
+				unordered = true
+			}
 			text = text[loc[1]:]
 			// Strip zero or more spaces followed by \n or a single space.
 			text = strings.TrimLeft(text, " ")
 			if len(text) > 0 && text[0] == '\n' {
 				text = text[1:]
 			}
-			return text, true
+			return text, unordered, true
 		}
 	}
-	return "", false // no suitable comment found
+	return "", false, false // no suitable comment found
 }
 
 // isTest tells whether name looks like a test, example, or benchmark.
@@ -255,7 +260,8 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
 		}
 	}
 
-	// Strip "Output:" comment and adjust body end position.
+	// Strip the "Output:" or "Unordered output:" comment and adjust body
+	// end position.
 	body, comments = stripOutputComment(body, comments)
 
 	// Synthesize import declaration.
@@ -318,10 +324,10 @@ func playExampleFile(file *ast.File) *ast.File {
 	return &f
 }
 
-// stripOutputComment finds and removes an "Output:" comment from body
-// and comments, and adjusts the body block's end position.
+// stripOutputComment finds and removes the "Output:" or "Unordered output:"
+// comment from body and comments, and adjusts the body block's end position.
 func stripOutputComment(body *ast.BlockStmt, comments []*ast.CommentGroup) (*ast.BlockStmt, []*ast.CommentGroup) {
-	// Do nothing if no "Output:" comment found.
+	// Do nothing if there is no "Output:" or "Unordered output:" comment.
 	i, last := lastComment(body, comments)
 	if last == nil || !outputPrefix.MatchString(last.Text()) {
 		return body, comments
diff --git a/libgo/go/go/doc/testdata/benchmark.go b/libgo/go/go/doc/testdata/benchmark.go
index 905e49644ad..1d581f057e6 100644
--- a/libgo/go/go/doc/testdata/benchmark.go
+++ b/libgo/go/go/doc/testdata/benchmark.go
@@ -33,7 +33,7 @@ type B struct {
 	result    BenchmarkResult
 }
 
-// StartTimer starts timing a test.  This function is called automatically
+// StartTimer starts timing a test. This function is called automatically
 // before a benchmark starts, but it can also used to resume timing after
 // a call to StopTimer.
 func (b *B) StartTimer() {
@@ -43,7 +43,7 @@ func (b *B) StartTimer() {
 	}
 }
 
-// StopTimer stops timing a test.  This can be used to pause the timer
+// StopTimer stops timing a test. This can be used to pause the timer
 // while performing complex initialization that you don't
 // want to measure.
 func (b *B) StopTimer() {
@@ -134,9 +134,9 @@ func (b *B) run() BenchmarkResult {
 	return b.result
 }
 
-// launch launches the benchmark function.  It gradually increases the number
+// launch launches the benchmark function. It gradually increases the number
 // of benchmark iterations until the benchmark runs for a second in order
-// to get a reasonable measurement.  It prints timing information in this form
+// to get a reasonable measurement. It prints timing information in this form
 //		testing.BenchmarkHello	100000		19 ns/op
 // launch is run by the fun function as a separate goroutine.
 func (b *B) launch() {
diff --git a/libgo/go/go/doc/testdata/testing.0.golden b/libgo/go/go/doc/testdata/testing.0.golden
index f8348f1ac34..83cf37cd3a9 100644
--- a/libgo/go/go/doc/testdata/testing.0.golden
+++ b/libgo/go/go/doc/testdata/testing.0.golden
@@ -78,10 +78,10 @@ TYPES
 	// SetBytes records the number of bytes processed in a single ...
 	func (b *B) SetBytes(n int64)
 
-	// StartTimer starts timing a test.  This function is called ...
+	// StartTimer starts timing a test. This function is called ...
 	func (b *B) StartTimer()
 
-	// StopTimer stops timing a test.  This can be used to pause the ...
+	// StopTimer stops timing a test. This can be used to pause the ...
 	func (b *B) StopTimer()
 
 	// The results of a benchmark run. 
diff --git a/libgo/go/go/doc/testdata/testing.1.golden b/libgo/go/go/doc/testdata/testing.1.golden
index 282bb1015ad..b9d14517a9c 100644
--- a/libgo/go/go/doc/testdata/testing.1.golden
+++ b/libgo/go/go/doc/testdata/testing.1.golden
@@ -25,8 +25,8 @@ VARIABLES
 	// 
 	var (
 		// The short flag requests that tests run more quickly, but its functionality
-		// is provided by test writers themselves.  The testing package is just its
-		// home.  The all.bash installation script sets it to make installation more
+		// is provided by test writers themselves. The testing package is just its
+		// home. The all.bash installation script sets it to make installation more
 		// efficient, but by default the flag is off so a plain "go test" will do a
 		// full test of the package.
 		short	= flag.Bool("test.short", false, "run smaller test suite to save time")
@@ -151,13 +151,13 @@ TYPES
 	// SetBytes records the number of bytes processed in a single ...
 	func (b *B) SetBytes(n int64)
 
-	// StartTimer starts timing a test.  This function is called ...
+	// StartTimer starts timing a test. This function is called ...
 	func (b *B) StartTimer()
 
-	// StopTimer stops timing a test.  This can be used to pause the ...
+	// StopTimer stops timing a test. This can be used to pause the ...
 	func (b *B) StopTimer()
 
-	// launch launches the benchmark function.  It gradually increases ...
+	// launch launches the benchmark function. It gradually increases ...
 	func (b *B) launch()
 
 	// log generates the output. It's always at the same stack depth. 
diff --git a/libgo/go/go/doc/testdata/testing.2.golden b/libgo/go/go/doc/testdata/testing.2.golden
index f8348f1ac34..83cf37cd3a9 100644
--- a/libgo/go/go/doc/testdata/testing.2.golden
+++ b/libgo/go/go/doc/testdata/testing.2.golden
@@ -78,10 +78,10 @@ TYPES
 	// SetBytes records the number of bytes processed in a single ...
 	func (b *B) SetBytes(n int64)
 
-	// StartTimer starts timing a test.  This function is called ...
+	// StartTimer starts timing a test. This function is called ...
 	func (b *B) StartTimer()
 
-	// StopTimer stops timing a test.  This can be used to pause the ...
+	// StopTimer stops timing a test. This can be used to pause the ...
 	func (b *B) StopTimer()
 
 	// The results of a benchmark run. 
diff --git a/libgo/go/go/doc/testdata/testing.go b/libgo/go/go/doc/testdata/testing.go
index 93ed494c32b..52810f7a564 100644
--- a/libgo/go/go/doc/testdata/testing.go
+++ b/libgo/go/go/doc/testdata/testing.go
@@ -22,7 +22,7 @@
 //         }
 //     }
 // The benchmark package will vary b.N until the benchmark function lasts
-// long enough to be timed reliably.  The output
+// long enough to be timed reliably. The output
 //     testing.BenchmarkHello    10000000    282 ns/op
 // means that the loop ran 10000000 times at a speed of 282 ns per loop.
 //
@@ -51,8 +51,8 @@ import (
 
 var (
 	// The short flag requests that tests run more quickly, but its functionality
-	// is provided by test writers themselves.  The testing package is just its
-	// home.  The all.bash installation script sets it to make installation more
+	// is provided by test writers themselves. The testing package is just its
+	// home. The all.bash installation script sets it to make installation more
 	// efficient, but by default the flag is off so a plain "go test" will do a
 	// full test of the package.
 	short = flag.Bool("test.short", false, "run smaller test suite to save time")
@@ -152,9 +152,9 @@ func (c *common) FailNow() {
 	// This previous version duplicated code (those lines are in
 	// tRunner no matter what), but worse the goroutine teardown
 	// implicit in runtime.Goexit was not guaranteed to complete
-	// before the test exited.  If a test deferred an important cleanup
+	// before the test exited. If a test deferred an important cleanup
 	// function (like removing temporary files), there was no guarantee
-	// it would run on a test failure.  Because we send on c.signal during
+	// it would run on a test failure. Because we send on c.signal during
 	// a top-of-stack deferred function now, we know that the send
 	// only happens after any other stacked defers have completed.
 	runtime.Goexit()
diff --git a/libgo/go/go/format/internal.go b/libgo/go/go/format/internal.go
index 9d04878f866..b8b470da8bb 100644
--- a/libgo/go/go/format/internal.go
+++ b/libgo/go/go/format/internal.go
@@ -28,9 +28,9 @@ func parse(fset *token.FileSet, filename string, src []byte, fragmentOk bool) (
 ) {
 	// Try as whole source file.
 	file, err = parser.ParseFile(fset, filename, src, parserMode)
-	// If there's no error, return.  If the error is that the source file didn't begin with a
+	// If there's no error, return. If the error is that the source file didn't begin with a
 	// package line and source fragments are ok, fall through to
-	// try as a source fragment.  Stop and return on any other error.
+	// try as a source fragment. Stop and return on any other error.
 	if err == nil || !fragmentOk || !strings.Contains(err.Error(), "expected 'package'") {
 		return
 	}
@@ -59,7 +59,7 @@ func parse(fset *token.FileSet, filename string, src []byte, fragmentOk bool) (
 
 	// If this is a statement list, make it a source file
 	// by inserting a package clause and turning the list
-	// into a function body.  This handles expressions too.
+	// into a function body. This handles expressions too.
 	// Insert using a ;, not a newline, so that the line numbers
 	// in fsrc match the ones in src. Add an extra '\n' before the '}'
 	// to make sure comments are flushed before the '}'.
diff --git a/libgo/go/go/importer/importer.go b/libgo/go/go/importer/importer.go
index 560b853c391..f655bc1e924 100644
--- a/libgo/go/go/importer/importer.go
+++ b/libgo/go/go/importer/importer.go
@@ -31,7 +31,7 @@ func For(compiler string, lookup Lookup) types.Importer {
 		return make(gcimports)
 
 	case "gccgo":
-		if lookup == nil {
+		if lookup != nil {
 			panic("gccgo importer for custom import path lookup not yet implemented")
 		}
 
diff --git a/libgo/go/go/internal/gccgoimporter/importer.go b/libgo/go/go/internal/gccgoimporter/importer.go
index aa0d01afdf3..19b9c735686 100644
--- a/libgo/go/go/internal/gccgoimporter/importer.go
+++ b/libgo/go/go/internal/gccgoimporter/importer.go
@@ -88,12 +88,6 @@ func openExportFile(fpath string) (reader io.ReadSeeker, closer io.Closer, err e
 	if err != nil {
 		return
 	}
-	// reset to offset 0 - needed on Plan 9 (see issue #11265)
-	// TODO: remove once issue #11265 has been resolved.
-	_, err = f.Seek(0, 0)
-	if err != nil {
-		return
-	}
 
 	var elfreader io.ReaderAt
 	switch string(magic[:]) {
@@ -168,7 +162,7 @@ func GetImporter(searchpaths []string, initmap map[*types.Package]InitData) Impo
 		if err != nil {
 			return
 		}
-		_, err = reader.Seek(0, 0)
+		_, err = reader.Seek(0, io.SeekStart)
 		if err != nil {
 			return
 		}
diff --git a/libgo/go/go/internal/gcimporter/bimport.go b/libgo/go/go/internal/gcimporter/bimport.go
index 68690424a16..75c2d9123e9 100644
--- a/libgo/go/go/internal/gcimporter/bimport.go
+++ b/libgo/go/go/internal/gcimporter/bimport.go
@@ -11,10 +11,34 @@ import (
 	"go/token"
 	"go/types"
 	"sort"
+	"strings"
 	"unicode"
 	"unicode/utf8"
 )
 
+type importer struct {
+	imports map[string]*types.Package
+	data    []byte
+	path    string
+	buf     []byte // for reading strings
+	version string
+
+	// object lists
+	strList       []string         // in order of appearance
+	pkgList       []*types.Package // in order of appearance
+	typList       []types.Type     // in order of appearance
+	trackAllTypes bool
+
+	// position encoding
+	posInfoFormat bool
+	prevFile      string
+	prevLine      int
+
+	// debugging support
+	debugFormat bool
+	read        int // bytes read
+}
+
 // BImportData imports a package from the serialized package data
 // and returns the number of bytes consumed and a reference to the package.
 // If data is obviously malformed, an error is returned but in
@@ -23,11 +47,12 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i
 	p := importer{
 		imports: imports,
 		data:    data,
+		path:    path,
+		strList: []string{""}, // empty string is mapped to 0
 	}
-	p.buf = p.bufarray[:]
 
 	// read low-level encoding format
-	switch format := p.byte(); format {
+	switch format := p.rawByte(); format {
 	case 'c':
 		// compact format - nothing to do
 	case 'd':
@@ -36,75 +61,49 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i
 		return p.read, nil, fmt.Errorf("invalid encoding format in export data: got %q; want 'c' or 'd'", format)
 	}
 
+	p.trackAllTypes = p.rawByte() == 'a'
+
+	p.posInfoFormat = p.int() != 0
+
 	// --- generic export data ---
 
-	if v := p.string(); v != "v0" {
-		return p.read, nil, fmt.Errorf("unknown version: %s", v)
+	p.version = p.string()
+	if p.version != "v0" && p.version != "v1" {
+		return p.read, nil, fmt.Errorf("unknown export data version: %s", p.version)
 	}
 
 	// populate typList with predeclared "known" types
 	p.typList = append(p.typList, predeclared...)
 
 	// read package data
-	// TODO(gri) clean this up
-	i := p.tagOrIndex()
-	if i != packageTag {
-		panic(fmt.Sprintf("package tag expected, got %d", i))
-	}
-	name := p.string()
-	if s := p.string(); s != "" {
-		panic(fmt.Sprintf("empty path expected, got %s", s))
-	}
-	pkg := p.imports[path]
-	if pkg == nil {
-		pkg = types.NewPackage(path, name)
-		p.imports[path] = pkg
-	}
-	p.pkgList = append(p.pkgList, pkg)
-
-	if debug && p.pkgList[0] != pkg {
-		panic("imported packaged not found in pkgList[0]")
-	}
-
-	// read compiler-specific flags
-	p.string() // discard
-
-	// read consts
-	for i := p.int(); i > 0; i-- {
-		name := p.string()
-		typ := p.typ(nil)
-		val := p.value()
-		p.declare(types.NewConst(token.NoPos, pkg, name, typ, val))
-	}
-
-	// read vars
-	for i := p.int(); i > 0; i-- {
-		name := p.string()
-		typ := p.typ(nil)
-		p.declare(types.NewVar(token.NoPos, pkg, name, typ))
-	}
-
-	// read funcs
-	for i := p.int(); i > 0; i-- {
-		name := p.string()
-		sig := p.typ(nil).(*types.Signature)
-		p.int() // read and discard index of inlined function body
-		p.declare(types.NewFunc(token.NoPos, pkg, name, sig))
+	pkg := p.pkg()
+
+	// read objects of phase 1 only (see cmd/compiler/internal/gc/bexport.go)
+	objcount := 0
+	for {
+		tag := p.tagOrIndex()
+		if tag == endTag {
+			break
+		}
+		p.obj(tag)
+		objcount++
 	}
 
-	// read types
-	for i := p.int(); i > 0; i-- {
-		// name is parsed as part of named type and the
-		// type object is added to scope via respective
-		// named type
-		_ = p.typ(nil).(*types.Named)
+	// self-verification
+	if count := p.int(); count != objcount {
+		panic(fmt.Sprintf("got %d objects; want %d", objcount, count))
 	}
 
 	// ignore compiler-specific import data
 
 	// complete interfaces
 	for _, typ := range p.typList {
-		if it, ok := typ.(*types.Interface); ok {
+		// If we only record named types (!p.trackAllTypes),
+		// we must check the underlying types here. If we
+		// track all types, the Underlying() method call is
+		// not needed.
+		// TODO(gri) Remove if p.trackAllTypes is gone.
+		if it, ok := typ.Underlying().(*types.Interface); ok {
 			it.Complete()
 		}
 	}
@@ -120,25 +119,6 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i
 	return p.read, pkg, nil
 }
 
-type importer struct {
-	imports  map[string]*types.Package
-	data     []byte
-	buf      []byte   // for reading strings
-	bufarray [64]byte // initial underlying array for buf, large enough to avoid allocation when compiling std lib
-	pkgList  []*types.Package
-	typList  []types.Type
-
-	debugFormat bool
-	read        int // bytes read
-}
-
-func (p *importer) declare(obj types.Object) {
-	if alt := p.pkgList[0].Scope().Insert(obj); alt != nil {
-		// This can only happen if we import a package a second time.
-		panic(fmt.Sprintf("%s already declared", alt.Name()))
-	}
-}
-
 func (p *importer) pkg() *types.Package {
 	// if the package was seen before, i is its index (>= 0)
 	i := p.tagOrIndex()
@@ -160,22 +140,100 @@ func (p *importer) pkg() *types.Package {
 		panic("empty package name in import")
 	}
 
-	// we should never see an empty import path
-	if path == "" {
-		panic("empty import path")
+	// an empty path denotes the package we are currently importing;
+	// it must be the first package we see
+	if (path == "") != (len(p.pkgList) == 0) {
+		panic(fmt.Sprintf("package path %q for pkg index %d", path, len(p.pkgList)))
 	}
 
 	// if the package was imported before, use that one; otherwise create a new one
+	if path == "" {
+		path = p.path
+	}
 	pkg := p.imports[path]
 	if pkg == nil {
 		pkg = types.NewPackage(path, name)
 		p.imports[path] = pkg
+	} else if pkg.Name() != name {
+		panic(fmt.Sprintf("conflicting names %s and %s for package %q", pkg.Name(), name, path))
 	}
 	p.pkgList = append(p.pkgList, pkg)
 
 	return pkg
 }
 
+func (p *importer) declare(obj types.Object) {
+	pkg := obj.Pkg()
+	if alt := pkg.Scope().Insert(obj); alt != nil {
+		// This could only trigger if we import a (non-type) object a second time.
+		// This should never happen because 1) we only import a package once; and
+		// b) we ignore compiler-specific export data which may contain functions
+		// whose inlined function bodies refer to other functions that were already
+		// imported.
+		// (See also the comment in cmd/compile/internal/gc/bimport.go importer.obj,
+		// switch case importing functions).
+		panic(fmt.Sprintf("inconsistent import:\n\t%v\npreviously imported as:\n\t%v\n", alt, obj))
+	}
+}
+
+func (p *importer) obj(tag int) {
+	switch tag {
+	case constTag:
+		p.pos()
+		pkg, name := p.qualifiedName()
+		typ := p.typ(nil)
+		val := p.value()
+		p.declare(types.NewConst(token.NoPos, pkg, name, typ, val))
+
+	case typeTag:
+		_ = p.typ(nil)
+
+	case varTag:
+		p.pos()
+		pkg, name := p.qualifiedName()
+		typ := p.typ(nil)
+		p.declare(types.NewVar(token.NoPos, pkg, name, typ))
+
+	case funcTag:
+		p.pos()
+		pkg, name := p.qualifiedName()
+		params, isddd := p.paramList()
+		result, _ := p.paramList()
+		sig := types.NewSignature(nil, params, result, isddd)
+		p.declare(types.NewFunc(token.NoPos, pkg, name, sig))
+
+	default:
+		panic(fmt.Sprintf("unexpected object tag %d", tag))
+	}
+}
+
+func (p *importer) pos() {
+	if !p.posInfoFormat {
+		return
+	}
+
+	file := p.prevFile
+	line := p.prevLine
+	if delta := p.int(); delta != 0 {
+		// line changed
+		line += delta
+	} else if n := p.int(); n >= 0 {
+		// file changed
+		file = p.prevFile[:n] + p.string()
+		p.prevFile = file
+		line = p.int()
+	}
+	p.prevLine = line
+
+	// TODO(gri) register new position
+}
+
+func (p *importer) qualifiedName() (pkg *types.Package, name string) {
+	name = p.string()
+	pkg = p.pkg()
+	return
+}
+
 func (p *importer) record(t types.Type) {
 	p.typList = append(p.typList, t)
 }
@@ -205,8 +263,8 @@ func (p *importer) typ(parent *types.Package) types.Type {
 	switch i {
 	case namedTag:
 		// read type object
-		name := p.string()
-		parent = p.pkg()
+		p.pos()
+		parent, name := p.qualifiedName()
 		scope := parent.Scope()
 		obj := scope.Lookup(name)
 
@@ -231,17 +289,27 @@ func (p *importer) typ(parent *types.Package) types.Type {
 		t0.SetUnderlying(p.typ(parent))
 
 		// interfaces don't have associated methods
-		if _, ok := t0.Underlying().(*types.Interface); ok {
+		if types.IsInterface(t0) {
 			return t
 		}
 
 		// read associated methods
 		for i := p.int(); i > 0; i-- {
+			// TODO(gri) replace this with something closer to fieldName
+			p.pos()
 			name := p.string()
+			if !exported(name) {
+				p.pkg()
+			}
+
 			recv, _ := p.paramList() // TODO(gri) do we need a full param list for the receiver?
 			params, isddd := p.paramList()
 			result, _ := p.paramList()
-			p.int() // read and discard index of inlined function body
+
+			if p.version == "v1" {
+				p.int() // nointerface flag - discarded
+			}
+
 			sig := types.NewSignature(recv.At(0), params, result, isddd)
 			t0.AddMethod(types.NewFunc(token.NoPos, parent, name, sig))
 		}
@@ -250,7 +318,9 @@ func (p *importer) typ(parent *types.Package) types.Type {
 
 	case arrayTag:
 		t := new(types.Array)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		n := p.int64()
 		*t = *types.NewArray(p.typ(parent), n)
@@ -258,42 +328,45 @@ func (p *importer) typ(parent *types.Package) types.Type {
 
 	case sliceTag:
 		t := new(types.Slice)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		*t = *types.NewSlice(p.typ(parent))
 		return t
 
 	case dddTag:
 		t := new(dddSlice)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		t.elem = p.typ(parent)
 		return t
 
 	case structTag:
 		t := new(types.Struct)
-		p.record(t)
-
-		n := p.int()
-		fields := make([]*types.Var, n)
-		tags := make([]string, n)
-		for i := range fields {
-			fields[i] = p.field(parent)
-			tags[i] = p.string()
+		if p.trackAllTypes {
+			p.record(t)
 		}
-		*t = *types.NewStruct(fields, tags)
+
+		*t = *types.NewStruct(p.fieldList(parent))
 		return t
 
 	case pointerTag:
 		t := new(types.Pointer)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		*t = *types.NewPointer(p.typ(parent))
 		return t
 
 	case signatureTag:
 		t := new(types.Signature)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		params, isddd := p.paramList()
 		result, _ := p.paramList()
@@ -306,30 +379,26 @@ func (p *importer) typ(parent *types.Package) types.Type {
 		// such cycle must contain a named type which would have been
 		// first defined earlier.
 		n := len(p.typList)
-		p.record(nil)
+		if p.trackAllTypes {
+			p.record(nil)
+		}
 
 		// no embedded interfaces with gc compiler
 		if p.int() != 0 {
 			panic("unexpected embedded interface")
 		}
 
-		// read methods
-		methods := make([]*types.Func, p.int())
-		for i := range methods {
-			pkg, name := p.fieldName(parent)
-			params, isddd := p.paramList()
-			result, _ := p.paramList()
-			sig := types.NewSignature(nil, params, result, isddd)
-			methods[i] = types.NewFunc(token.NoPos, pkg, name, sig)
+		t := types.NewInterface(p.methodList(parent), nil)
+		if p.trackAllTypes {
+			p.typList[n] = t
 		}
-
-		t := types.NewInterface(methods, nil)
-		p.typList[n] = t
 		return t
 
 	case mapTag:
 		t := new(types.Map)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		key := p.typ(parent)
 		val := p.typ(parent)
@@ -338,7 +407,9 @@ func (p *importer) typ(parent *types.Package) types.Type {
 
 	case chanTag:
 		t := new(types.Chan)
-		p.record(t)
+		if p.trackAllTypes {
+			p.record(t)
+		}
 
 		var dir types.ChanDir
 		// tag values must match the constants in cmd/compile/internal/gc/go.go
@@ -361,7 +432,20 @@ func (p *importer) typ(parent *types.Package) types.Type {
 	}
 }
 
+func (p *importer) fieldList(parent *types.Package) (fields []*types.Var, tags []string) {
+	if n := p.int(); n > 0 {
+		fields = make([]*types.Var, n)
+		tags = make([]string, n)
+		for i := range fields {
+			fields[i] = p.field(parent)
+			tags[i] = p.string()
+		}
+	}
+	return
+}
+
 func (p *importer) field(parent *types.Package) *types.Var {
+	p.pos()
 	pkg, name := p.fieldName(parent)
 	typ := p.typ(parent)
 
@@ -383,6 +467,25 @@ func (p *importer) field(parent *types.Package) *types.Var {
 	return types.NewField(token.NoPos, pkg, name, typ, anonymous)
 }
 
+func (p *importer) methodList(parent *types.Package) (methods []*types.Func) {
+	if n := p.int(); n > 0 {
+		methods = make([]*types.Func, n)
+		for i := range methods {
+			methods[i] = p.method(parent)
+		}
+	}
+	return
+}
+
+func (p *importer) method(parent *types.Package) *types.Func {
+	p.pos()
+	pkg, name := p.fieldName(parent)
+	params, isddd := p.paramList()
+	result, _ := p.paramList()
+	sig := types.NewSignature(nil, params, result, isddd)
+	return types.NewFunc(token.NoPos, pkg, name, sig)
+}
+
 func (p *importer) fieldName(parent *types.Package) (*types.Package, string) {
 	pkg := parent
 	if pkg == nil {
@@ -430,18 +533,25 @@ func (p *importer) param(named bool) (*types.Var, bool) {
 		t = types.NewSlice(td.elem)
 	}
 
+	var pkg *types.Package
 	var name string
 	if named {
 		name = p.string()
 		if name == "" {
 			panic("expected named parameter")
 		}
+		if name != "_" {
+			pkg = p.pkg()
+		}
+		if i := strings.Index(name, "·"); i > 0 {
+			name = name[:i] // cut off gc-specific parameter numbering
+		}
 	}
 
 	// read and discard compiler-specific info
 	p.string()
 
-	return types.NewVar(token.NoPos, nil, name, t), isddd
+	return types.NewVar(token.NoPos, pkg, name, t), isddd
 }
 
 func exported(name string) bool {
@@ -546,24 +656,28 @@ func (p *importer) string() string {
 	if p.debugFormat {
 		p.marker('s')
 	}
-
-	if n := int(p.rawInt64()); n > 0 {
-		if cap(p.buf) < n {
-			p.buf = make([]byte, n)
-		} else {
-			p.buf = p.buf[:n]
-		}
-		for i := 0; i < n; i++ {
-			p.buf[i] = p.byte()
-		}
-		return string(p.buf)
+	// if the string was seen before, i is its index (>= 0)
+	// (the empty string is at index 0)
+	i := p.rawInt64()
+	if i >= 0 {
+		return p.strList[i]
 	}
-
-	return ""
+	// otherwise, i is the negative string length (< 0)
+	if n := int(-i); n <= cap(p.buf) {
+		p.buf = p.buf[:n]
+	} else {
+		p.buf = make([]byte, n)
+	}
+	for i := range p.buf {
+		p.buf[i] = p.rawByte()
+	}
+	s := string(p.buf)
+	p.strList = append(p.strList, s)
+	return s
 }
 
 func (p *importer) marker(want byte) {
-	if got := p.byte(); got != want {
+	if got := p.rawByte(); got != want {
 		panic(fmt.Sprintf("incorrect marker: got %c; want %c (pos = %d)", got, want, p.read))
 	}
 
@@ -584,12 +698,13 @@ func (p *importer) rawInt64() int64 {
 
 // needed for binary.ReadVarint in rawInt64
 func (p *importer) ReadByte() (byte, error) {
-	return p.byte(), nil
+	return p.rawByte(), nil
 }
 
 // byte is the bottleneck interface for reading p.data.
 // It unescapes '|' 'S' to '$' and '|' '|' to '|'.
-func (p *importer) byte() byte {
+// rawByte should only be used by low-level decoders.
+func (p *importer) rawByte() byte {
 	b := p.data[0]
 	r := 1
 	if b == '|' {
@@ -615,8 +730,13 @@ func (p *importer) byte() byte {
 
 // Tags. Must be < 0.
 const (
-	// Packages
+	// Objects
 	packageTag = -(iota + 1)
+	constTag
+	typeTag
+	varTag
+	funcTag
+	endTag
 
 	// Types
 	namedTag
@@ -638,6 +758,7 @@ const (
 	fractionTag // not used by gc
 	complexTag
 	stringTag
+	unknownTag // not used by gc (only appears in packages with errors)
 )
 
 var predeclared = []types.Type{
@@ -678,4 +799,15 @@ var predeclared = []types.Type{
 
 	// package unsafe
 	types.Typ[types.UnsafePointer],
+
+	// invalid type
+	types.Typ[types.Invalid], // only appears in packages with errors
+
+	// used internally by gc; never used by this package or in .a files
+	anyType{},
 }
+
+type anyType struct{}
+
+func (t anyType) Underlying() types.Type { return t }
+func (t anyType) String() string         { return "any" }
diff --git a/libgo/go/go/internal/gcimporter/exportdata.go b/libgo/go/go/internal/gcimporter/exportdata.go
index 18bea415ae4..4c0d2fe7616 100644
--- a/libgo/go/go/internal/gcimporter/exportdata.go
+++ b/libgo/go/go/internal/gcimporter/exportdata.go
@@ -52,33 +52,11 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 	if string(line) == "!<arch>\n" {
 		// Archive file. Scan to __.PKGDEF.
 		var name string
-		var size int
-		if name, size, err = readGopackHeader(r); err != nil {
+		if name, _, err = readGopackHeader(r); err != nil {
 			return
 		}
 
-		// Optional leading __.GOSYMDEF or __.SYMDEF.
-		// Read and discard.
-		if name == "__.SYMDEF" || name == "__.GOSYMDEF" {
-			const block = 4096
-			tmp := make([]byte, block)
-			for size > 0 {
-				n := size
-				if n > block {
-					n = block
-				}
-				if _, err = io.ReadFull(r, tmp[:n]); err != nil {
-					return
-				}
-				size -= n
-			}
-
-			if name, _, err = readGopackHeader(r); err != nil {
-				return
-			}
-		}
-
-		// First real entry should be __.PKGDEF.
+		// First entry should be __.PKGDEF.
 		if name != "__.PKGDEF" {
 			err = errors.New("go archive is missing __.PKGDEF")
 			return
diff --git a/libgo/go/go/internal/gcimporter/gcimporter.go b/libgo/go/go/internal/gcimporter/gcimporter.go
index d70ec083c33..2c6e676225f 100644
--- a/libgo/go/go/internal/gcimporter/gcimporter.go
+++ b/libgo/go/go/internal/gcimporter/gcimporter.go
@@ -163,7 +163,7 @@ func Import(packages map[string]*types.Package, path, srcDir string) (pkg *types
 		var data []byte
 		data, err = ioutil.ReadAll(buf)
 		if err == nil {
-			_, pkg, err = BImportData(packages, data, path)
+			_, pkg, err = BImportData(packages, data, id)
 			return
 		}
 	default:
@@ -385,7 +385,7 @@ func (p *parser) getPkg(id, name string) *types.Package {
 		if pname := pkg.Name(); pname == "" {
 			pkg.SetName(name)
 		} else if pname != name {
-			p.errorf("%s package name mismatch: %s (given) vs %s (expected)", pname, name)
+			p.errorf("%s package name mismatch: %s (given) vs %s (expected)", id, pname, name)
 		}
 	}
 	return pkg
@@ -451,7 +451,7 @@ func (p *parser) parseMapType(parent *types.Package) types.Type {
 // For qualified names, the returned package is nil (and not created if
 // it doesn't exist yet) unless materializePkg is set (which creates an
 // unnamed package with valid package path). In the latter case, a
-// subequent import clause is expected to provide a name for the package.
+// subsequent import clause is expected to provide a name for the package.
 //
 func (p *parser) parseName(parent *types.Package, materializePkg bool) (pkg *types.Package, name string) {
 	pkg = parent
diff --git a/libgo/go/go/internal/gcimporter/gcimporter_test.go b/libgo/go/go/internal/gcimporter/gcimporter_test.go
index e56720b0d52..d8c5bcfb1ca 100644
--- a/libgo/go/go/internal/gcimporter/gcimporter_test.go
+++ b/libgo/go/go/internal/gcimporter/gcimporter_test.go
@@ -351,9 +351,9 @@ func TestIssue13898(t *testing.T) {
 	}
 
 	// lookup go/types.Object.Pkg method
-	m, _, _ := types.LookupFieldOrMethod(typ, false, nil, "Pkg")
+	m, index, indirect := types.LookupFieldOrMethod(typ, false, nil, "Pkg")
 	if m == nil {
-		t.Fatal("go/types.Object.Pkg not found")
+		t.Fatalf("go/types.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
 	}
 
 	// the method must belong to go/types
@@ -361,3 +361,67 @@ func TestIssue13898(t *testing.T) {
 		t.Fatalf("found %v; want go/types", m.Pkg())
 	}
 }
+
+func TestIssue15517(t *testing.T) {
+	skipSpecialPlatforms(t)
+
+	// This package only handles gc export data.
+	if runtime.Compiler != "gc" {
+		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
+		return
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	if f := compile(t, "testdata", "p.go"); f != "" {
+		defer os.Remove(f)
+	}
+
+	// Multiple imports of p must succeed without redeclaration errors.
+	// We use an import path that's not cleaned up so that the eventual
+	// file path for the package is different from the package path; this
+	// will expose the error if it is present.
+	//
+	// (Issue: Both the textual and the binary importer used the file path
+	// of the package to be imported as key into the shared packages map.
+	// However, the binary importer then used the package path to identify
+	// the imported package to mark it as complete; effectively marking the
+	// wrong package as complete. By using an "unclean" package path, the
+	// file and package path are different, exposing the problem if present.
+	// The same issue occurs with vendoring.)
+	imports := make(map[string]*types.Package)
+	for i := 0; i < 3; i++ {
+		if _, err := Import(imports, "./././testdata/p", "."); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+func TestIssue15920(t *testing.T) {
+	skipSpecialPlatforms(t)
+
+	// This package only handles gc export data.
+	if runtime.Compiler != "gc" {
+		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
+		return
+	}
+
+	// On windows, we have to set the -D option for the compiler to avoid having a drive
+	// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
+	if runtime.GOOS == "windows" {
+		t.Skip("avoid dealing with relative paths/drive letters on windows")
+	}
+
+	if f := compile(t, "testdata", "issue15920.go"); f != "" {
+		defer os.Remove(f)
+	}
+
+	imports := make(map[string]*types.Package)
+	if _, err := Import(imports, "./testdata/issue15920", "."); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/libgo/go/go/internal/gcimporter/testdata/issue15920.go b/libgo/go/go/internal/gcimporter/testdata/issue15920.go
new file mode 100644
index 00000000000..c70f7d8267b
--- /dev/null
+++ b/libgo/go/go/internal/gcimporter/testdata/issue15920.go
@@ -0,0 +1,11 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+// The underlying type of Error is the underlying type of error.
+// Make sure we can import this again without problems.
+type Error error
+
+func F() Error { return nil }
diff --git a/libgo/go/go/internal/gcimporter/testdata/p.go b/libgo/go/go/internal/gcimporter/testdata/p.go
new file mode 100644
index 00000000000..9e2e7057653
--- /dev/null
+++ b/libgo/go/go/internal/gcimporter/testdata/p.go
@@ -0,0 +1,13 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Input for TestIssue15517
+
+package p
+
+const C = 0
+
+var V int
+
+func F() {}
diff --git a/libgo/go/go/parser/interface.go b/libgo/go/go/parser/interface.go
index c6fd93240af..bff79cab462 100644
--- a/libgo/go/go/parser/interface.go
+++ b/libgo/go/go/parser/interface.go
@@ -73,7 +73,7 @@ const (
 //
 // The mode parameter controls the amount of source text parsed and other
 // optional parser functionality. Position information is recorded in the
-// file set fset.
+// file set fset, which must not be nil.
 //
 // If the source couldn't be read, the returned AST is nil and the error
 // indicates the specific failure. If the source was read but syntax
@@ -82,6 +82,10 @@ const (
 // are returned via a scanner.ErrorList which is sorted by file position.
 //
 func ParseFile(fset *token.FileSet, filename string, src interface{}, mode Mode) (f *ast.File, err error) {
+	if fset == nil {
+		panic("parser.ParseFile: no token.FileSet provided (fset == nil)")
+	}
+
 	// get source
 	text, err := readSource(filename, src)
 	if err != nil {
@@ -125,7 +129,8 @@ func ParseFile(fset *token.FileSet, filename string, src interface{}, mode Mode)
 //
 // If filter != nil, only the files with os.FileInfo entries passing through
 // the filter (and ending in ".go") are considered. The mode bits are passed
-// to ParseFile unchanged. Position information is recorded in fset.
+// to ParseFile unchanged. Position information is recorded in fset, which
+// must not be nil.
 //
 // If the directory couldn't be read, a nil map and the respective error are
 // returned. If a parse error occurred, a non-nil but incomplete map and the
@@ -169,9 +174,14 @@ func ParseDir(fset *token.FileSet, path string, filter func(os.FileInfo) bool, m
 
 // ParseExprFrom is a convenience function for parsing an expression.
 // The arguments have the same meaning as for Parse, but the source must
-// be a valid Go (type or value) expression.
+// be a valid Go (type or value) expression. Specifically, fset must not
+// be nil.
 //
 func ParseExprFrom(fset *token.FileSet, filename string, src interface{}, mode Mode) (ast.Expr, error) {
+	if fset == nil {
+		panic("parser.ParseExprFrom: no token.FileSet provided (fset == nil)")
+	}
+
 	// get source
 	text, err := readSource(filename, src)
 	if err != nil {
diff --git a/libgo/go/go/parser/parser.go b/libgo/go/go/parser/parser.go
index f3a26032eec..d3ef7db31ea 100644
--- a/libgo/go/go/parser/parser.go
+++ b/libgo/go/go/parser/parser.go
@@ -1597,23 +1597,19 @@ func (p *parser) parseBinaryExpr(lhs bool, prec1 int) ast.Expr {
 	}
 
 	x := p.parseUnaryExpr(lhs)
-	for _, prec := p.tokPrec(); prec >= prec1; prec-- {
-		for {
-			op, oprec := p.tokPrec()
-			if oprec != prec {
-				break
-			}
-			pos := p.expect(op)
-			if lhs {
-				p.resolve(x)
-				lhs = false
-			}
-			y := p.parseBinaryExpr(false, prec+1)
-			x = &ast.BinaryExpr{X: p.checkExpr(x), OpPos: pos, Op: op, Y: p.checkExpr(y)}
+	for {
+		op, oprec := p.tokPrec()
+		if oprec < prec1 {
+			return x
+		}
+		pos := p.expect(op)
+		if lhs {
+			p.resolve(x)
+			lhs = false
 		}
+		y := p.parseBinaryExpr(false, oprec+1)
+		x = &ast.BinaryExpr{X: p.checkExpr(x), OpPos: pos, Op: op, Y: p.checkExpr(y)}
 	}
-
-	return x
 }
 
 // If lhs is set and the result is an identifier, it is not resolved.
diff --git a/libgo/go/go/scanner/scanner.go b/libgo/go/go/scanner/scanner.go
index e9476c4dee4..ce660c71d5c 100644
--- a/libgo/go/go/scanner/scanner.go
+++ b/libgo/go/go/scanner/scanner.go
@@ -26,7 +26,7 @@ import (
 type ErrorHandler func(pos token.Position, msg string)
 
 // A Scanner holds the scanner's internal state while processing
-// a given text.  It can be allocated as part of another data
+// a given text. It can be allocated as part of another data
 // structure but must be initialized via Init before use.
 //
 type Scanner struct {
@@ -64,7 +64,7 @@ func (s *Scanner) next() {
 		switch {
 		case r == 0:
 			s.error(s.offset, "illegal character NUL")
-		case r >= 0x80:
+		case r >= utf8.RuneSelf:
 			// not ASCII
 			r, w = utf8.DecodeRune(s.src[s.rdOffset:])
 			if r == utf8.RuneError && w == 1 {
@@ -255,11 +255,11 @@ func (s *Scanner) findLineEnd() bool {
 }
 
 func isLetter(ch rune) bool {
-	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 0x80 && unicode.IsLetter(ch)
+	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= utf8.RuneSelf && unicode.IsLetter(ch)
 }
 
 func isDigit(ch rune) bool {
-	return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch)
+	return '0' <= ch && ch <= '9' || ch >= utf8.RuneSelf && unicode.IsDigit(ch)
 }
 
 func (s *Scanner) scanIdentifier() string {
diff --git a/libgo/go/go/token/position.go b/libgo/go/go/token/position.go
index 33751779a3d..7306083b0dd 100644
--- a/libgo/go/go/token/position.go
+++ b/libgo/go/go/token/position.go
@@ -164,6 +164,7 @@ func (f *File) MergeLine(line int) {
 // Each line offset must be larger than the offset for the previous line
 // and smaller than the file size; otherwise SetLines fails and returns
 // false.
+// Callers must not mutate the provided slice after SetLines returns.
 //
 func (f *File) SetLines(lines []int) bool {
 	// verify validity of lines table
diff --git a/libgo/go/go/types/api_test.go b/libgo/go/go/types/api_test.go
index 97af965c9f6..33cdb5d62c0 100644
--- a/libgo/go/go/types/api_test.go
+++ b/libgo/go/go/types/api_test.go
@@ -573,6 +573,47 @@ func TestInitOrderInfo(t *testing.T) {
 		`, []string{
 			"a = next()", "b = next()", "c = next()", "d = next()", "e = next()", "f = next()", "_ = makeOrder()",
 		}},
+		// test case for issue 10709
+		// TODO(gri) enable once the issue is fixed
+		// {`package p13
+
+		// var (
+		//     v = t.m()
+		//     t = makeT(0)
+		// )
+
+		// type T struct{}
+
+		// func (T) m() int { return 0 }
+
+		// func makeT(n int) T {
+		//     if n > 0 {
+		//         return makeT(n-1)
+		//     }
+		//     return T{}
+		// }`, []string{
+		// 	"t = makeT(0)", "v = t.m()",
+		// }},
+		// test case for issue 10709: same as test before, but variable decls swapped
+		{`package p14
+
+		var (
+		    t = makeT(0)
+		    v = t.m()
+		)
+
+		type T struct{}
+
+		func (T) m() int { return 0 }
+
+		func makeT(n int) T {
+		    if n > 0 {
+		        return makeT(n-1)
+		    }
+		    return T{}
+		}`, []string{
+			"t = makeT(0)", "v = t.m()",
+		}},
 	}
 
 	for _, test := range tests {
@@ -1044,3 +1085,45 @@ func f() {
 		}
 	}
 }
+
+func TestIdentical_issue15173(t *testing.T) {
+	// Identical should allow nil arguments and be symmetric.
+	for _, test := range []struct {
+		x, y Type
+		want bool
+	}{
+		{Typ[Int], Typ[Int], true},
+		{Typ[Int], nil, false},
+		{nil, Typ[Int], false},
+		{nil, nil, true},
+	} {
+		if got := Identical(test.x, test.y); got != test.want {
+			t.Errorf("Identical(%v, %v) = %t", test.x, test.y, got)
+		}
+	}
+}
+
+func TestIssue15305(t *testing.T) {
+	const src = "package p; func f() int16; var _ = f(undef)"
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "issue15305.go", src, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	conf := Config{
+		Error: func(err error) {}, // allow errors
+	}
+	info := &Info{
+		Types: make(map[ast.Expr]TypeAndValue),
+	}
+	conf.Check("p", fset, []*ast.File{f}, info) // ignore result
+	for e, tv := range info.Types {
+		if _, ok := e.(*ast.CallExpr); ok {
+			if tv.Type != Typ[Int16] {
+				t.Errorf("CallExpr has type %v, want int16", tv.Type)
+			}
+			return
+		}
+	}
+	t.Errorf("CallExpr has no type")
+}
diff --git a/libgo/go/go/types/assignments.go b/libgo/go/go/types/assignments.go
index 10ab17b9cf9..6ebf3b5eab0 100644
--- a/libgo/go/go/types/assignments.go
+++ b/libgo/go/go/types/assignments.go
@@ -179,6 +179,14 @@ func (check *Checker) assignVar(lhs ast.Expr, x *operand) Type {
 	case variable, mapindex:
 		// ok
 	default:
+		if sel, ok := z.expr.(*ast.SelectorExpr); ok {
+			var op operand
+			check.expr(&op, sel.X)
+			if op.mode == mapindex {
+				check.errorf(z.pos(), "cannot assign to struct field %s in map", ExprString(z.expr))
+				return nil
+			}
+		}
 		check.errorf(z.pos(), "cannot assign to %s", &z)
 		return nil
 	}
diff --git a/libgo/go/go/types/builtins.go b/libgo/go/go/types/builtins.go
index 803264fb585..0082be9e2e9 100644
--- a/libgo/go/go/types/builtins.go
+++ b/libgo/go/go/types/builtins.go
@@ -366,7 +366,7 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 			} else {
 				// an untyped non-constant argument may appear if
 				// it contains a (yet untyped non-constant) shift
-				// epression: convert it to complex128 which will
+				// expression: convert it to complex128 which will
 				// result in an error (shift of complex value)
 				check.convertUntyped(x, Typ[Complex128])
 				// x should be invalid now, but be conservative and check
diff --git a/libgo/go/go/types/call.go b/libgo/go/go/types/call.go
index 8aeb862993f..45f3e9a6056 100644
--- a/libgo/go/go/types/call.go
+++ b/libgo/go/go/types/call.go
@@ -62,14 +62,12 @@ func (check *Checker) call(x *operand, e *ast.CallExpr) exprKind {
 		}
 
 		arg, n, _ := unpack(func(x *operand, i int) { check.multiExpr(x, e.Args[i]) }, len(e.Args), false)
-		if arg == nil {
+		if arg != nil {
+			check.arguments(x, e, sig, arg, n)
+		} else {
 			x.mode = invalid
-			x.expr = e
-			return statement
 		}
 
-		check.arguments(x, e, sig, arg, n)
-
 		// determine result
 		switch sig.results.Len() {
 		case 0:
@@ -81,6 +79,7 @@ func (check *Checker) call(x *operand, e *ast.CallExpr) exprKind {
 			x.mode = value
 			x.typ = sig.results
 		}
+
 		x.expr = e
 		check.hasCallOrRecv = true
 
diff --git a/libgo/go/go/types/check.go b/libgo/go/go/types/check.go
index bb0b07415e8..0279be0e848 100644
--- a/libgo/go/go/types/check.go
+++ b/libgo/go/go/types/check.go
@@ -215,7 +215,9 @@ func (check *Checker) handleBailout(err *error) {
 }
 
 // Files checks the provided files as part of the checker's package.
-func (check *Checker) Files(files []*ast.File) (err error) {
+func (check *Checker) Files(files []*ast.File) error { return check.checkFiles(files) }
+
+func (check *Checker) checkFiles(files []*ast.File) (err error) {
 	defer check.handleBailout(&err)
 
 	check.initFiles(files)
diff --git a/libgo/go/go/types/decl.go b/libgo/go/go/types/decl.go
index f064f6856f2..1ecfb35f60c 100644
--- a/libgo/go/go/types/decl.go
+++ b/libgo/go/go/types/decl.go
@@ -141,6 +141,14 @@ func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
 	// determine type, if any
 	if typ != nil {
 		obj.typ = check.typ(typ)
+		// We cannot spread the type to all lhs variables if there
+		// are more than one since that would mark them as checked
+		// (see Checker.objDecl) and the assignment of init exprs,
+		// if any, would not be checked.
+		//
+		// TODO(gri) If we have no init expr, we should distribute
+		// a given type otherwise we need to re-evalate the type
+		// expr for each lhs variable, leading to duplicate work.
 	}
 
 	// check initialization
@@ -173,6 +181,17 @@ func (check *Checker) varDecl(obj *Var, lhs []*Var, typ, init ast.Expr) {
 			panic("inconsistent lhs")
 		}
 	}
+
+	// We have multiple variables on the lhs and one init expr.
+	// Make sure all variables have been given the same type if
+	// one was specified, otherwise they assume the type of the
+	// init expression values (was issue #15755).
+	if typ != nil {
+		for _, lhs := range lhs {
+			lhs.typ = obj.typ
+		}
+	}
+
 	check.initVars(lhs, []ast.Expr{init}, token.NoPos)
 }
 
diff --git a/libgo/go/go/types/eval.go b/libgo/go/go/types/eval.go
index 7b42ff1a9d0..831d771d807 100644
--- a/libgo/go/go/types/eval.go
+++ b/libgo/go/go/types/eval.go
@@ -34,7 +34,7 @@ import (
 // level untyped constants will return an untyped type rather then the
 // respective context-specific type.
 //
-func Eval(fset *token.FileSet, pkg *Package, pos token.Pos, expr string) (tv TypeAndValue, err error) {
+func Eval(fset *token.FileSet, pkg *Package, pos token.Pos, expr string) (TypeAndValue, error) {
 	// determine scope
 	var scope *Scope
 	if pkg == nil {
@@ -44,7 +44,7 @@ func Eval(fset *token.FileSet, pkg *Package, pos token.Pos, expr string) (tv Typ
 		scope = pkg.scope
 	} else {
 		// The package scope extent (position information) may be
-		// incorrect (files spread accross a wide range of fset
+		// incorrect (files spread across a wide range of fset
 		// positions) - ignore it and just consider its children
 		// (file scopes).
 		for _, fscope := range pkg.scope.children {
diff --git a/libgo/go/go/types/expr.go b/libgo/go/go/types/expr.go
index f7c4a173785..4430c45d140 100644
--- a/libgo/go/go/types/expr.go
+++ b/libgo/go/go/types/expr.go
@@ -660,10 +660,10 @@ func (check *Checker) shift(x, y *operand, e *ast.BinaryExpr, op token.Token) {
 				return
 			}
 			// rhs must be within reasonable bounds
-			const stupidShift = 1023 - 1 + 52 // so we can express smallestFloat64
+			const shiftBound = 1023 - 1 + 52 // so we can express smallestFloat64
 			s, ok := constant.Uint64Val(yval)
-			if !ok || s > stupidShift {
-				check.invalidOp(y.pos(), "stupid shift count %s", y)
+			if !ok || s > shiftBound {
+				check.invalidOp(y.pos(), "invalid shift count %s", y)
 				x.mode = invalid
 				return
 			}
diff --git a/libgo/go/go/types/hilbert_test.go b/libgo/go/go/types/hilbert_test.go
index bf2a15b26a3..07d5a635e0c 100644
--- a/libgo/go/go/types/hilbert_test.go
+++ b/libgo/go/go/types/hilbert_test.go
@@ -195,19 +195,6 @@ func (g *gen) printProduct(n int) {
 	g.p("}\n\n")
 }
 
-func (g *gen) mulRange(a, b int) {
-	if a > b {
-		g.p("1")
-		return
-	}
-	for i := a; i <= b; i++ {
-		if i > a {
-			g.p("*")
-		}
-		g.p("%d", i)
-	}
-}
-
 func (g *gen) binomials(n int) {
 	g.p(`// Binomials
 const (
diff --git a/libgo/go/go/types/initorder.go b/libgo/go/go/types/initorder.go
index 0fd567b2691..cf9b8709d8d 100644
--- a/libgo/go/go/types/initorder.go
+++ b/libgo/go/go/types/initorder.go
@@ -12,28 +12,43 @@ import (
 // initOrder computes the Info.InitOrder for package variables.
 func (check *Checker) initOrder() {
 	// An InitOrder may already have been computed if a package is
-	// built from several calls to (*Checker).Files.  Clear it.
+	// built from several calls to (*Checker).Files. Clear it.
 	check.Info.InitOrder = check.Info.InitOrder[:0]
 
-	// compute the object dependency graph and
-	// initialize a priority queue with the list
-	// of graph nodes
+	// Compute the transposed object dependency graph and initialize
+	// a priority queue with the list of graph nodes.
 	pq := nodeQueue(dependencyGraph(check.objMap))
 	heap.Init(&pq)
 
 	const debug = false
 	if debug {
-		fmt.Printf("package %s: object dependency graph\n", check.pkg.Name())
+		fmt.Printf("Computing initialization order for %s\n\n", check.pkg)
+		fmt.Println("Object dependency graph:")
+		for obj, d := range check.objMap {
+			if len(d.deps) > 0 {
+				fmt.Printf("\t%s depends on\n", obj.Name())
+				for dep := range d.deps {
+					fmt.Printf("\t\t%s\n", dep.Name())
+				}
+			} else {
+				fmt.Printf("\t%s has no dependencies\n", obj.Name())
+			}
+		}
+		fmt.Println()
+
+		fmt.Println("Transposed object dependency graph:")
 		for _, n := range pq {
-			for _, o := range n.out {
-				fmt.Printf("\t%s -> %s\n", n.obj.Name(), o.obj.Name())
+			fmt.Printf("\t%s depends on %d nodes\n", n.obj.Name(), n.in)
+			for _, out := range n.out {
+				fmt.Printf("\t\t%s is dependent\n", out.obj.Name())
 			}
 		}
 		fmt.Println()
-		fmt.Printf("package %s: initialization order\n", check.pkg.Name())
+
+		fmt.Println("Processing nodes:")
 	}
 
-	// determine initialization order by removing the highest priority node
+	// Determine initialization order by removing the highest priority node
 	// (the one with the fewest dependencies) and its edges from the graph,
 	// repeatedly, until there are no nodes left.
 	// In a valid Go program, those nodes always have zero dependencies (after
@@ -45,6 +60,11 @@ func (check *Checker) initOrder() {
 		// get the next node
 		n := heap.Pop(&pq).(*objNode)
 
+		if debug {
+			fmt.Printf("\t%s (src pos %d) depends on %d nodes now\n",
+				n.obj.Name(), n.obj.order(), n.in)
+		}
+
 		// if n still depends on other nodes, we have a cycle
 		if n.in > 0 {
 			mark++ // mark nodes using a different value each time
@@ -86,14 +106,15 @@ func (check *Checker) initOrder() {
 		}
 		init := &Initializer{infoLhs, info.init}
 		check.Info.InitOrder = append(check.Info.InitOrder, init)
-
-		if debug {
-			fmt.Printf("\t%s\n", init)
-		}
 	}
 
 	if debug {
 		fmt.Println()
+		fmt.Println("Initialization order:")
+		for _, init := range check.Info.InitOrder {
+			fmt.Printf("\t%s\n", init)
+		}
+		fmt.Println()
 	}
 }
 
diff --git a/libgo/go/go/types/labels.go b/libgo/go/go/types/labels.go
index 7364d4dbe68..3b43b4ba05c 100644
--- a/libgo/go/go/types/labels.go
+++ b/libgo/go/go/types/labels.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/go/types/object.go b/libgo/go/go/types/object.go
index b835c6e53e8..707b806d3fc 100644
--- a/libgo/go/go/types/object.go
+++ b/libgo/go/go/types/object.go
@@ -188,7 +188,7 @@ func (obj *Var) Anonymous() bool { return obj.anonymous }
 func (obj *Var) IsField() bool { return obj.isField }
 
 // A Func represents a declared function, concrete method, or abstract
-// (interface) method.  Its Type() is always a *Signature.
+// (interface) method. Its Type() is always a *Signature.
 // An abstract method may belong to many interfaces due to embedding.
 type Func struct {
 	object
diff --git a/libgo/go/go/types/package.go b/libgo/go/go/types/package.go
index 4a432b54960..a588ee73dce 100644
--- a/libgo/go/go/types/package.go
+++ b/libgo/go/go/types/package.go
@@ -55,7 +55,7 @@ func (pkg *Package) MarkComplete() { pkg.complete = true }
 // pkg; the list is in source order. Package unsafe is excluded.
 //
 // If pkg was loaded from export data, Imports includes packages that
-// provide package-level objects referenced by pkg.  This may be more or
+// provide package-level objects referenced by pkg. This may be more or
 // less than the set of packages directly imported by pkg's source code.
 func (pkg *Package) Imports() []*Package { return pkg.imports }
 
diff --git a/libgo/go/go/types/predicates.go b/libgo/go/go/types/predicates.go
index 993c6d290b1..5509069fb63 100644
--- a/libgo/go/go/types/predicates.go
+++ b/libgo/go/go/types/predicates.go
@@ -277,6 +277,8 @@ func identical(x, y Type, p *ifacePair) bool {
 			return x.obj == y.obj
 		}
 
+	case nil:
+
 	default:
 		unreachable()
 	}
diff --git a/libgo/go/go/types/resolver.go b/libgo/go/go/types/resolver.go
index 1536df5bf1b..cb8e72e4a6a 100644
--- a/libgo/go/go/types/resolver.go
+++ b/libgo/go/go/types/resolver.go
@@ -32,7 +32,7 @@ func (d *declInfo) hasInitializer() bool {
 	return d.init != nil || d.fdecl != nil && d.fdecl.Body != nil
 }
 
-// addDep adds obj as a dependency to d.
+// addDep adds obj to the set of objects d's init expression depends on.
 func (d *declInfo) addDep(obj Object) {
 	m := d.deps
 	if m == nil {
@@ -67,7 +67,7 @@ func (check *Checker) arityMatch(s, init *ast.ValueSpec) {
 			// TODO(gri) avoid declared but not used error here
 		} else {
 			// init exprs "inherited"
-			check.errorf(s.Pos(), "extra init expr at %s", init.Pos())
+			check.errorf(s.Pos(), "extra init expr at %s", check.fset.Position(init.Pos()))
 			// TODO(gri) avoid declared but not used error here
 		}
 	case l > r && (init != nil || r != 1):
diff --git a/libgo/go/go/types/return.go b/libgo/go/go/types/return.go
index 66289852147..0c1447f89b3 100644
--- a/libgo/go/go/types/return.go
+++ b/libgo/go/go/types/return.go
@@ -83,8 +83,13 @@ func (check *Checker) isTerminating(s ast.Stmt, label string) bool {
 }
 
 func (check *Checker) isTerminatingList(list []ast.Stmt, label string) bool {
-	n := len(list)
-	return n > 0 && check.isTerminating(list[n-1], label)
+	// trailing empty statements are permitted - skip them
+	for i := len(list) - 1; i >= 0; i-- {
+		if _, ok := list[i].(*ast.EmptyStmt); !ok {
+			return check.isTerminating(list[i], label)
+		}
+	}
+	return false // all statements are empty
 }
 
 func (check *Checker) isTerminatingSwitch(body *ast.BlockStmt, label string) bool {
diff --git a/libgo/go/go/types/scope.go b/libgo/go/go/types/scope.go
index 3502840225f..b5d34d6e655 100644
--- a/libgo/go/go/types/scope.go
+++ b/libgo/go/go/types/scope.go
@@ -31,7 +31,7 @@ type Scope struct {
 }
 
 // NewScope returns a new, empty scope contained in the given parent
-// scope, if any.  The comment is for debugging only.
+// scope, if any. The comment is for debugging only.
 func NewScope(parent *Scope, pos, end token.Pos, comment string) *Scope {
 	s := &Scope{parent, nil, nil, pos, end, comment}
 	// don't add children to Universe scope!
diff --git a/libgo/go/go/types/stdlib_test.go b/libgo/go/go/types/stdlib_test.go
index c63bfbb9a4e..e40734f147f 100644
--- a/libgo/go/go/types/stdlib_test.go
+++ b/libgo/go/go/types/stdlib_test.go
@@ -160,6 +160,7 @@ func TestStdFixed(t *testing.T) {
 		"issue6889.go",  // gc-specific test
 		"issue7746.go",  // large constants - consumes too much memory
 		"issue11362.go", // canonical import path check
+		"issue15002.go", // uses Mmap; testTestDir should consult build tags
 	)
 }
 
@@ -273,13 +274,16 @@ func walkDirs(t *testing.T, dir string) {
 	}
 
 	// typecheck package in directory
-	files, err := pkgFilenames(dir)
-	if err != nil {
-		t.Error(err)
-		return
-	}
-	if files != nil {
-		typecheck(t, dir, files)
+	// but ignore files directly under $GOROOT/src (might be temporary test files).
+	if dir != filepath.Join(runtime.GOROOT(), "src") {
+		files, err := pkgFilenames(dir)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if files != nil {
+			typecheck(t, dir, files)
+		}
 	}
 
 	// traverse subdirectories, but don't walk into testdata
diff --git a/libgo/go/go/types/stmt.go b/libgo/go/go/types/stmt.go
index e0129cf0e09..5764430b1bf 100644
--- a/libgo/go/go/types/stmt.go
+++ b/libgo/go/go/types/stmt.go
@@ -83,9 +83,19 @@ func (check *Checker) simpleStmt(s ast.Stmt) {
 	}
 }
 
+func trimTrailingEmptyStmts(list []ast.Stmt) []ast.Stmt {
+	for i := len(list); i > 0; i-- {
+		if _, ok := list[i-1].(*ast.EmptyStmt); !ok {
+			return list[:i]
+		}
+	}
+	return nil
+}
+
 func (check *Checker) stmtList(ctxt stmtContext, list []ast.Stmt) {
 	ok := ctxt&fallthroughOk != 0
 	inner := ctxt &^ fallthroughOk
+	list = trimTrailingEmptyStmts(list) // trailing empty statements are "invisible" to fallthrough analysis
 	for i, s := range list {
 		inner := inner
 		if ok && i+1 == len(list) {
@@ -113,7 +123,7 @@ func (check *Checker) multipleDefaults(list []ast.Stmt) {
 		}
 		if d != nil {
 			if first != nil {
-				check.errorf(d.Pos(), "multiple defaults (first at %s)", first.Pos())
+				check.errorf(d.Pos(), "multiple defaults (first at %s)", check.fset.Position(first.Pos()))
 			} else {
 				first = d
 			}
@@ -346,7 +356,17 @@ func (check *Checker) stmt(ctxt stmtContext, s ast.Stmt) {
 			check.invalidAST(s.TokPos, "unknown inc/dec operation %s", s.Tok)
 			return
 		}
+
 		var x operand
+		check.expr(&x, s.X)
+		if x.mode == invalid {
+			return
+		}
+		if !isNumeric(x.typ) {
+			check.invalidOp(s.X.Pos(), "%s%s (non-numeric type %s)", s.X, s.Tok, x.typ)
+			return
+		}
+
 		Y := &ast.BasicLit{ValuePos: s.X.Pos(), Kind: token.INT, Value: "1"} // use x's position
 		check.binary(&x, nil, s.X, Y, op)
 		if x.mode == invalid {
diff --git a/libgo/go/go/types/type.go b/libgo/go/go/types/type.go
index d8415f1fdf2..4e00da3212f 100644
--- a/libgo/go/go/types/type.go
+++ b/libgo/go/go/types/type.go
@@ -229,7 +229,7 @@ func NewSignature(recv *Var, params, results *Tuple, variadic bool) *Signature {
 // function.
 //
 // For an abstract method, Recv returns the enclosing interface either
-// as a *Named or an *Interface.  Due to embedding, an interface may
+// as a *Named or an *Interface. Due to embedding, an interface may
 // contain methods whose receiver type is a different interface.
 func (s *Signature) Recv() *Var { return s.recv }
 
diff --git a/libgo/go/go/types/universe.go b/libgo/go/go/types/universe.go
index 40185c1ad42..cc3bd5a370b 100644
--- a/libgo/go/go/types/universe.go
+++ b/libgo/go/go/types/universe.go
@@ -196,7 +196,7 @@ func init() {
 //
 func def(obj Object) {
 	name := obj.Name()
-	if strings.Index(name, " ") >= 0 {
+	if strings.Contains(name, " ") {
 		return // nothing to do
 	}
 	// fix Obj link for named types
diff --git a/libgo/go/internal/golang.org/x/net/http2/hpack/encode.go b/libgo/go/golang_org/x/net/http2/hpack/encode.go
index 80d621cf355..f9bb0339848 100644
--- a/libgo/go/internal/golang.org/x/net/http2/hpack/encode.go
+++ b/libgo/go/golang_org/x/net/http2/hpack/encode.go
@@ -144,7 +144,7 @@ func (e *Encoder) SetMaxDynamicTableSizeLimit(v uint32) {
 
 // shouldIndex reports whether f should be indexed.
 func (e *Encoder) shouldIndex(f HeaderField) bool {
-	return !f.Sensitive && f.size() <= e.dynTab.maxSize
+	return !f.Sensitive && f.Size() <= e.dynTab.maxSize
 }
 
 // appendIndexed appends index i, as encoded in "Indexed Header Field"
diff --git a/libgo/go/internal/golang.org/x/net/http2/hpack/encode_test.go b/libgo/go/golang_org/x/net/http2/hpack/encode_test.go
index 92286f3bad1..92286f3bad1 100644
--- a/libgo/go/internal/golang.org/x/net/http2/hpack/encode_test.go
+++ b/libgo/go/golang_org/x/net/http2/hpack/encode_test.go
diff --git a/libgo/go/internal/golang.org/x/net/http2/hpack/hpack.go b/libgo/go/golang_org/x/net/http2/hpack/hpack.go
index 2ea4949ab08..8aa197ad678 100644
--- a/libgo/go/internal/golang.org/x/net/http2/hpack/hpack.go
+++ b/libgo/go/golang_org/x/net/http2/hpack/hpack.go
@@ -41,6 +41,14 @@ type HeaderField struct {
 	Sensitive bool
 }
 
+// IsPseudo reports whether the header field is an http2 pseudo header.
+// That is, it reports whether it starts with a colon.
+// It is not otherwise guaranteed to be a valid pseudo header field,
+// though.
+func (hf HeaderField) IsPseudo() bool {
+	return len(hf.Name) != 0 && hf.Name[0] == ':'
+}
+
 func (hf HeaderField) String() string {
 	var suffix string
 	if hf.Sensitive {
@@ -49,7 +57,8 @@ func (hf HeaderField) String() string {
 	return fmt.Sprintf("header field %q = %q%s", hf.Name, hf.Value, suffix)
 }
 
-func (hf *HeaderField) size() uint32 {
+// Size returns the size of an entry per RFC 7540 section 5.2.
+func (hf HeaderField) Size() uint32 {
 	// http://http2.github.io/http2-spec/compression.html#rfc.section.4.1
 	// "The size of the dynamic table is the sum of the size of
 	// its entries.  The size of an entry is the sum of its name's
@@ -171,7 +180,7 @@ func (dt *dynamicTable) setMaxSize(v uint32) {
 
 func (dt *dynamicTable) add(f HeaderField) {
 	dt.ents = append(dt.ents, f)
-	dt.size += f.size()
+	dt.size += f.Size()
 	dt.evict()
 }
 
@@ -179,7 +188,7 @@ func (dt *dynamicTable) add(f HeaderField) {
 func (dt *dynamicTable) evict() {
 	base := dt.ents // keep base pointer of slice
 	for dt.size > dt.maxSize {
-		dt.size -= dt.ents[0].size()
+		dt.size -= dt.ents[0].Size()
 		dt.ents = dt.ents[1:]
 	}
 
diff --git a/libgo/go/internal/golang.org/x/net/http2/hpack/hpack_test.go b/libgo/go/golang_org/x/net/http2/hpack/hpack_test.go
index 6dc69f95799..4c7b17bfb14 100644
--- a/libgo/go/internal/golang.org/x/net/http2/hpack/hpack_test.go
+++ b/libgo/go/golang_org/x/net/http2/hpack/hpack_test.go
@@ -524,6 +524,47 @@ func testDecodeSeries(t *testing.T, size uint32, steps []encAndWant) {
 	}
 }
 
+func TestHuffmanDecodeExcessPadding(t *testing.T) {
+	tests := [][]byte{
+		{0xff},                                   // Padding Exceeds 7 bits
+		{0x1f, 0xff},                             // {"a", 1 byte excess padding}
+		{0x1f, 0xff, 0xff},                       // {"a", 2 byte excess padding}
+		{0x1f, 0xff, 0xff, 0xff},                 // {"a", 3 byte excess padding}
+		{0xff, 0x9f, 0xff, 0xff, 0xff},           // {"a", 29 bit excess padding}
+		{'R', 0xbc, '0', 0xff, 0xff, 0xff, 0xff}, // Padding ends on partial symbol.
+	}
+	for i, in := range tests {
+		var buf bytes.Buffer
+		if _, err := HuffmanDecode(&buf, in); err != ErrInvalidHuffman {
+			t.Errorf("test-%d: decode(%q) = %v; want ErrInvalidHuffman", i, in, err)
+		}
+	}
+}
+
+func TestHuffmanDecodeEOS(t *testing.T) {
+	in := []byte{0xff, 0xff, 0xff, 0xff, 0xfc} // {EOS, "?"}
+	var buf bytes.Buffer
+	if _, err := HuffmanDecode(&buf, in); err != ErrInvalidHuffman {
+		t.Errorf("error = %v; want ErrInvalidHuffman", err)
+	}
+}
+
+func TestHuffmanDecodeMaxLengthOnTrailingByte(t *testing.T) {
+	in := []byte{0x00, 0x01} // {"0", "0", "0"}
+	var buf bytes.Buffer
+	if err := huffmanDecode(&buf, 2, in); err != ErrStringLength {
+		t.Errorf("error = %v; want ErrStringLength", err)
+	}
+}
+
+func TestHuffmanDecodeCorruptPadding(t *testing.T) {
+	in := []byte{0x00}
+	var buf bytes.Buffer
+	if _, err := HuffmanDecode(&buf, in); err != ErrInvalidHuffman {
+		t.Errorf("error = %v; want ErrInvalidHuffman", err)
+	}
+}
+
 func TestHuffmanDecode(t *testing.T) {
 	tests := []struct {
 		inHex, want string
diff --git a/libgo/go/internal/golang.org/x/net/http2/hpack/huffman.go b/libgo/go/golang_org/x/net/http2/hpack/huffman.go
index eb4b1f05cd0..8850e394677 100644
--- a/libgo/go/internal/golang.org/x/net/http2/hpack/huffman.go
+++ b/libgo/go/golang_org/x/net/http2/hpack/huffman.go
@@ -48,12 +48,16 @@ var ErrInvalidHuffman = errors.New("hpack: invalid Huffman-encoded data")
 // maxLen bytes will return ErrStringLength.
 func huffmanDecode(buf *bytes.Buffer, maxLen int, v []byte) error {
 	n := rootHuffmanNode
-	cur, nbits := uint(0), uint8(0)
+	// cur is the bit buffer that has not been fed into n.
+	// cbits is the number of low order bits in cur that are valid.
+	// sbits is the number of bits of the symbol prefix being decoded.
+	cur, cbits, sbits := uint(0), uint8(0), uint8(0)
 	for _, b := range v {
 		cur = cur<<8 | uint(b)
-		nbits += 8
-		for nbits >= 8 {
-			idx := byte(cur >> (nbits - 8))
+		cbits += 8
+		sbits += 8
+		for cbits >= 8 {
+			idx := byte(cur >> (cbits - 8))
 			n = n.children[idx]
 			if n == nil {
 				return ErrInvalidHuffman
@@ -63,22 +67,40 @@ func huffmanDecode(buf *bytes.Buffer, maxLen int, v []byte) error {
 					return ErrStringLength
 				}
 				buf.WriteByte(n.sym)
-				nbits -= n.codeLen
+				cbits -= n.codeLen
 				n = rootHuffmanNode
+				sbits = cbits
 			} else {
-				nbits -= 8
+				cbits -= 8
 			}
 		}
 	}
-	for nbits > 0 {
-		n = n.children[byte(cur<<(8-nbits))]
-		if n.children != nil || n.codeLen > nbits {
+	for cbits > 0 {
+		n = n.children[byte(cur<<(8-cbits))]
+		if n == nil {
+			return ErrInvalidHuffman
+		}
+		if n.children != nil || n.codeLen > cbits {
 			break
 		}
+		if maxLen != 0 && buf.Len() == maxLen {
+			return ErrStringLength
+		}
 		buf.WriteByte(n.sym)
-		nbits -= n.codeLen
+		cbits -= n.codeLen
 		n = rootHuffmanNode
+		sbits = cbits
+	}
+	if sbits > 7 {
+		// Either there was an incomplete symbol, or overlong padding.
+		// Both are decoding errors per RFC 7541 section 5.2.
+		return ErrInvalidHuffman
 	}
+	if mask := uint(1<<cbits - 1); cur&mask != mask {
+		// Trailing bits must be a prefix of EOS per RFC 7541 section 5.2.
+		return ErrInvalidHuffman
+	}
+
 	return nil
 }
 
diff --git a/libgo/go/internal/golang.org/x/net/http2/hpack/tables.go b/libgo/go/golang_org/x/net/http2/hpack/tables.go
index b9283a02330..b9283a02330 100644
--- a/libgo/go/internal/golang.org/x/net/http2/hpack/tables.go
+++ b/libgo/go/golang_org/x/net/http2/hpack/tables.go
diff --git a/libgo/go/golang_org/x/net/lex/httplex/httplex.go b/libgo/go/golang_org/x/net/lex/httplex/httplex.go
new file mode 100644
index 00000000000..bd0ec24f444
--- /dev/null
+++ b/libgo/go/golang_org/x/net/lex/httplex/httplex.go
@@ -0,0 +1,312 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package httplex contains rules around lexical matters of various
+// HTTP-related specifications.
+//
+// This package is shared by the standard library (which vendors it)
+// and x/net/http2. It comes with no API stability promise.
+package httplex
+
+import (
+	"strings"
+	"unicode/utf8"
+)
+
+var isTokenTable = [127]bool{
+	'!':  true,
+	'#':  true,
+	'$':  true,
+	'%':  true,
+	'&':  true,
+	'\'': true,
+	'*':  true,
+	'+':  true,
+	'-':  true,
+	'.':  true,
+	'0':  true,
+	'1':  true,
+	'2':  true,
+	'3':  true,
+	'4':  true,
+	'5':  true,
+	'6':  true,
+	'7':  true,
+	'8':  true,
+	'9':  true,
+	'A':  true,
+	'B':  true,
+	'C':  true,
+	'D':  true,
+	'E':  true,
+	'F':  true,
+	'G':  true,
+	'H':  true,
+	'I':  true,
+	'J':  true,
+	'K':  true,
+	'L':  true,
+	'M':  true,
+	'N':  true,
+	'O':  true,
+	'P':  true,
+	'Q':  true,
+	'R':  true,
+	'S':  true,
+	'T':  true,
+	'U':  true,
+	'W':  true,
+	'V':  true,
+	'X':  true,
+	'Y':  true,
+	'Z':  true,
+	'^':  true,
+	'_':  true,
+	'`':  true,
+	'a':  true,
+	'b':  true,
+	'c':  true,
+	'd':  true,
+	'e':  true,
+	'f':  true,
+	'g':  true,
+	'h':  true,
+	'i':  true,
+	'j':  true,
+	'k':  true,
+	'l':  true,
+	'm':  true,
+	'n':  true,
+	'o':  true,
+	'p':  true,
+	'q':  true,
+	'r':  true,
+	's':  true,
+	't':  true,
+	'u':  true,
+	'v':  true,
+	'w':  true,
+	'x':  true,
+	'y':  true,
+	'z':  true,
+	'|':  true,
+	'~':  true,
+}
+
+func IsTokenRune(r rune) bool {
+	i := int(r)
+	return i < len(isTokenTable) && isTokenTable[i]
+}
+
+func isNotToken(r rune) bool {
+	return !IsTokenRune(r)
+}
+
+// HeaderValuesContainsToken reports whether any string in values
+// contains the provided token, ASCII case-insensitively.
+func HeaderValuesContainsToken(values []string, token string) bool {
+	for _, v := range values {
+		if headerValueContainsToken(v, token) {
+			return true
+		}
+	}
+	return false
+}
+
+// isOWS reports whether b is an optional whitespace byte, as defined
+// by RFC 7230 section 3.2.3.
+func isOWS(b byte) bool { return b == ' ' || b == '\t' }
+
+// trimOWS returns x with all optional whitespace removes from the
+// beginning and end.
+func trimOWS(x string) string {
+	// TODO: consider using strings.Trim(x, " \t") instead,
+	// if and when it's fast enough. See issue 10292.
+	// But this ASCII-only code will probably always beat UTF-8
+	// aware code.
+	for len(x) > 0 && isOWS(x[0]) {
+		x = x[1:]
+	}
+	for len(x) > 0 && isOWS(x[len(x)-1]) {
+		x = x[:len(x)-1]
+	}
+	return x
+}
+
+// headerValueContainsToken reports whether v (assumed to be a
+// 0#element, in the ABNF extension described in RFC 7230 section 7)
+// contains token amongst its comma-separated tokens, ASCII
+// case-insensitively.
+func headerValueContainsToken(v string, token string) bool {
+	v = trimOWS(v)
+	if comma := strings.IndexByte(v, ','); comma != -1 {
+		return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token)
+	}
+	return tokenEqual(v, token)
+}
+
+// lowerASCII returns the ASCII lowercase version of b.
+func lowerASCII(b byte) byte {
+	if 'A' <= b && b <= 'Z' {
+		return b + ('a' - 'A')
+	}
+	return b
+}
+
+// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.
+func tokenEqual(t1, t2 string) bool {
+	if len(t1) != len(t2) {
+		return false
+	}
+	for i, b := range t1 {
+		if b >= utf8.RuneSelf {
+			// No UTF-8 or non-ASCII allowed in tokens.
+			return false
+		}
+		if lowerASCII(byte(b)) != lowerASCII(t2[i]) {
+			return false
+		}
+	}
+	return true
+}
+
+// isLWS reports whether b is linear white space, according
+// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
+//      LWS            = [CRLF] 1*( SP | HT )
+func isLWS(b byte) bool { return b == ' ' || b == '\t' }
+
+// isCTL reports whether b is a control byte, according
+// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
+//      CTL            = <any US-ASCII control character
+//                       (octets 0 - 31) and DEL (127)>
+func isCTL(b byte) bool {
+	const del = 0x7f // a CTL
+	return b < ' ' || b == del
+}
+
+// ValidHeaderFieldName reports whether v is a valid HTTP/1.x header name.
+// HTTP/2 imposes the additional restriction that uppercase ASCII
+// letters are not allowed.
+//
+//  RFC 7230 says:
+//   header-field   = field-name ":" OWS field-value OWS
+//   field-name     = token
+//   token          = 1*tchar
+//   tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
+//           "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA
+func ValidHeaderFieldName(v string) bool {
+	if len(v) == 0 {
+		return false
+	}
+	for _, r := range v {
+		if !IsTokenRune(r) {
+			return false
+		}
+	}
+	return true
+}
+
+// ValidHostHeader reports whether h is a valid host header.
+func ValidHostHeader(h string) bool {
+	// The latest spec is actually this:
+	//
+	// http://tools.ietf.org/html/rfc7230#section-5.4
+	//     Host = uri-host [ ":" port ]
+	//
+	// Where uri-host is:
+	//     http://tools.ietf.org/html/rfc3986#section-3.2.2
+	//
+	// But we're going to be much more lenient for now and just
+	// search for any byte that's not a valid byte in any of those
+	// expressions.
+	for i := 0; i < len(h); i++ {
+		if !validHostByte[h[i]] {
+			return false
+		}
+	}
+	return true
+}
+
+// See the validHostHeader comment.
+var validHostByte = [256]bool{
+	'0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true, '7': true,
+	'8': true, '9': true,
+
+	'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true, 'h': true,
+	'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true, 'o': true, 'p': true,
+	'q': true, 'r': true, 's': true, 't': true, 'u': true, 'v': true, 'w': true, 'x': true,
+	'y': true, 'z': true,
+
+	'A': true, 'B': true, 'C': true, 'D': true, 'E': true, 'F': true, 'G': true, 'H': true,
+	'I': true, 'J': true, 'K': true, 'L': true, 'M': true, 'N': true, 'O': true, 'P': true,
+	'Q': true, 'R': true, 'S': true, 'T': true, 'U': true, 'V': true, 'W': true, 'X': true,
+	'Y': true, 'Z': true,
+
+	'!':  true, // sub-delims
+	'$':  true, // sub-delims
+	'%':  true, // pct-encoded (and used in IPv6 zones)
+	'&':  true, // sub-delims
+	'(':  true, // sub-delims
+	')':  true, // sub-delims
+	'*':  true, // sub-delims
+	'+':  true, // sub-delims
+	',':  true, // sub-delims
+	'-':  true, // unreserved
+	'.':  true, // unreserved
+	':':  true, // IPv6address + Host expression's optional port
+	';':  true, // sub-delims
+	'=':  true, // sub-delims
+	'[':  true,
+	'\'': true, // sub-delims
+	']':  true,
+	'_':  true, // unreserved
+	'~':  true, // unreserved
+}
+
+// ValidHeaderFieldValue reports whether v is a valid "field-value" according to
+// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2 :
+//
+//        message-header = field-name ":" [ field-value ]
+//        field-value    = *( field-content | LWS )
+//        field-content  = <the OCTETs making up the field-value
+//                         and consisting of either *TEXT or combinations
+//                         of token, separators, and quoted-string>
+//
+// http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 :
+//
+//        TEXT           = <any OCTET except CTLs,
+//                          but including LWS>
+//        LWS            = [CRLF] 1*( SP | HT )
+//        CTL            = <any US-ASCII control character
+//                         (octets 0 - 31) and DEL (127)>
+//
+// RFC 7230 says:
+//  field-value    = *( field-content / obs-fold )
+//  obj-fold       =  N/A to http2, and deprecated
+//  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]
+//  field-vchar    = VCHAR / obs-text
+//  obs-text       = %x80-FF
+//  VCHAR          = "any visible [USASCII] character"
+//
+// http2 further says: "Similarly, HTTP/2 allows header field values
+// that are not valid. While most of the values that can be encoded
+// will not alter header field parsing, carriage return (CR, ASCII
+// 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII
+// 0x0) might be exploited by an attacker if they are translated
+// verbatim. Any request or response that contains a character not
+// permitted in a header field value MUST be treated as malformed
+// (Section 8.1.2.6). Valid characters are defined by the
+// field-content ABNF rule in Section 3.2 of [RFC7230]."
+//
+// This function does not (yet?) properly handle the rejection of
+// strings that begin or end with SP or HTAB.
+func ValidHeaderFieldValue(v string) bool {
+	for i := 0; i < len(v); i++ {
+		b := v[i]
+		if isCTL(b) && !isLWS(b) {
+			return false
+		}
+	}
+	return true
+}
diff --git a/libgo/go/net/http/lex_test.go b/libgo/go/golang_org/x/net/lex/httplex/httplex_test.go
index 986fda17dcd..c4ace1991b3 100644
--- a/libgo/go/net/http/lex_test.go
+++ b/libgo/go/golang_org/x/net/lex/httplex/httplex_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package http
+package httplex
 
 import (
 	"testing"
@@ -24,7 +24,7 @@ func TestIsToken(t *testing.T) {
 	for i := 0; i <= 130; i++ {
 		r := rune(i)
 		expected := isChar(r) && !isCtl(r) && !isSeparator(r)
-		if isToken(r) != expected {
+		if IsTokenRune(r) != expected {
 			t.Errorf("isToken(0x%x) = %v", r, !expected)
 		}
 	}
@@ -93,7 +93,7 @@ func TestHeaderValuesContainsToken(t *testing.T) {
 		},
 	}
 	for _, tt := range tests {
-		got := headerValuesContainsToken(tt.vals, tt.token)
+		got := HeaderValuesContainsToken(tt.vals, tt.token)
 		if got != tt.want {
 			t.Errorf("headerValuesContainsToken(%q, %q) = %v; want %v", tt.vals, tt.token, got, tt.want)
 		}
diff --git a/libgo/go/golang_org/x/net/route/address.go b/libgo/go/golang_org/x/net/route/address.go
new file mode 100644
index 00000000000..206a8371d43
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/address.go
@@ -0,0 +1,269 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+import "runtime"
+
+// An Addr represents an address associated with packet routing.
+type Addr interface {
+	// Family returns an address family.
+	Family() int
+}
+
+// A LinkAddr represents a link-layer address.
+type LinkAddr struct {
+	Index int    // interface index when attached
+	Name  string // interface name when attached
+	Addr  []byte // link-layer address when attached
+}
+
+// Family implements the Family method of Addr interface.
+func (a *LinkAddr) Family() int { return sysAF_LINK }
+
+func parseLinkAddr(b []byte) (Addr, error) {
+	if len(b) < 8 {
+		return nil, errInvalidAddr
+	}
+	_, a, err := parseKernelLinkAddr(sysAF_LINK, b[4:])
+	if err != nil {
+		return nil, err
+	}
+	a.(*LinkAddr).Index = int(nativeEndian.Uint16(b[2:4]))
+	return a, nil
+}
+
+// parseKernelLinkAddr parses b as a link-layer address in
+// conventional BSD kernel form.
+func parseKernelLinkAddr(_ int, b []byte) (int, Addr, error) {
+	// The encoding looks like the following:
+	// +----------------------------+
+	// | Type             (1 octet) |
+	// +----------------------------+
+	// | Name length      (1 octet) |
+	// +----------------------------+
+	// | Address length   (1 octet) |
+	// +----------------------------+
+	// | Selector length  (1 octet) |
+	// +----------------------------+
+	// | Data            (variable) |
+	// +----------------------------+
+	//
+	// On some platforms, all-bit-one of length field means "don't
+	// care".
+	nlen, alen, slen := int(b[1]), int(b[2]), int(b[3])
+	if nlen == 0xff {
+		nlen = 0
+	}
+	if alen == 0xff {
+		alen = 0
+	}
+	if slen == 0xff {
+		slen = 0
+	}
+	l := 4 + nlen + alen + slen
+	if len(b) < l {
+		return 0, nil, errInvalidAddr
+	}
+	data := b[4:]
+	var name string
+	var addr []byte
+	if nlen > 0 {
+		name = string(data[:nlen])
+		data = data[nlen:]
+	}
+	if alen > 0 {
+		addr = data[:alen]
+		data = data[alen:]
+	}
+	return l, &LinkAddr{Name: name, Addr: addr}, nil
+}
+
+// An Inet4Addr represents an internet address for IPv4.
+type Inet4Addr struct {
+	IP [4]byte // IP address
+}
+
+// Family implements the Family method of Addr interface.
+func (a *Inet4Addr) Family() int { return sysAF_INET }
+
+// An Inet6Addr represents an internet address for IPv6.
+type Inet6Addr struct {
+	IP     [16]byte // IP address
+	ZoneID int      // zone identifier
+}
+
+// Family implements the Family method of Addr interface.
+func (a *Inet6Addr) Family() int { return sysAF_INET6 }
+
+// parseInetAddr parses b as an internet address for IPv4 or IPv6.
+func parseInetAddr(af int, b []byte) (Addr, error) {
+	switch af {
+	case sysAF_INET:
+		if len(b) < 16 {
+			return nil, errInvalidAddr
+		}
+		a := &Inet4Addr{}
+		copy(a.IP[:], b[4:8])
+		return a, nil
+	case sysAF_INET6:
+		if len(b) < 28 {
+			return nil, errInvalidAddr
+		}
+		a := &Inet6Addr{ZoneID: int(nativeEndian.Uint32(b[24:28]))}
+		copy(a.IP[:], b[8:24])
+		if a.IP[0] == 0xfe && a.IP[1]&0xc0 == 0x80 || a.IP[0] == 0xff && (a.IP[1]&0x0f == 0x01 || a.IP[1]&0x0f == 0x02) {
+			// KAME based IPv6 protocol stack usually
+			// embeds the interface index in the
+			// interface-local or link-local address as
+			// the kernel-internal form.
+			id := int(bigEndian.Uint16(a.IP[2:4]))
+			if id != 0 {
+				a.ZoneID = id
+				a.IP[2], a.IP[3] = 0, 0
+			}
+		}
+		return a, nil
+	default:
+		return nil, errInvalidAddr
+	}
+}
+
+// parseKernelInetAddr parses b as an internet address in conventional
+// BSD kernel form.
+func parseKernelInetAddr(af int, b []byte) (int, Addr, error) {
+	// The encoding looks similar to the NLRI encoding.
+	// +----------------------------+
+	// | Length           (1 octet) |
+	// +----------------------------+
+	// | Address prefix  (variable) |
+	// +----------------------------+
+	//
+	// The differences between the kernel form and the NLRI
+	// encoding are:
+	//
+	// - The length field of the kernel form indicates the prefix
+	//   length in bytes, not in bits
+	//
+	// - In the kernel form, zero value of the length field
+	//   doesn't mean 0.0.0.0/0 or ::/0
+	//
+	// - The kernel form appends leading bytes to the prefix field
+	//   to make the <length, prefix> tuple to be conformed with
+	//   the routing message boundary
+	l := int(b[0])
+	if runtime.GOOS == "darwin" {
+		// On Darwn, an address in the kernel form is also
+		// used as a message filler.
+		if l == 0 || len(b) > roundup(l) {
+			l = roundup(l)
+		}
+	} else {
+		l = roundup(l)
+	}
+	if len(b) < l {
+		return 0, nil, errInvalidAddr
+	}
+	// Don't reorder case expressions.
+	// The case expressions for IPv6 must come first.
+	const (
+		off4 = 4 // offset of in_addr
+		off6 = 8 // offset of in6_addr
+	)
+	switch {
+	case b[0] == 28: // size of sockaddr_in6
+		a := &Inet6Addr{}
+		copy(a.IP[:], b[off6:off6+16])
+		return int(b[0]), a, nil
+	case af == sysAF_INET6:
+		a := &Inet6Addr{}
+		if l-1 < off6 {
+			copy(a.IP[:], b[1:l])
+		} else {
+			copy(a.IP[:], b[l-off6:l])
+		}
+		return int(b[0]), a, nil
+	case b[0] == 16: // size of sockaddr_in
+		a := &Inet4Addr{}
+		copy(a.IP[:], b[off4:off4+4])
+		return int(b[0]), a, nil
+	default: // an old fashion, AF_UNSPEC or unknown means AF_INET
+		a := &Inet4Addr{}
+		if l-1 < off4 {
+			copy(a.IP[:], b[1:l])
+		} else {
+			copy(a.IP[:], b[l-off4:l])
+		}
+		return int(b[0]), a, nil
+	}
+}
+
+// A DefaultAddr represents an address of various operating
+// system-specific features.
+type DefaultAddr struct {
+	af  int
+	Raw []byte // raw format of address
+}
+
+// Family implements the Family method of Addr interface.
+func (a *DefaultAddr) Family() int { return a.af }
+
+func parseDefaultAddr(b []byte) (Addr, error) {
+	if len(b) < 2 || len(b) < int(b[0]) {
+		return nil, errInvalidAddr
+	}
+	a := &DefaultAddr{af: int(b[1]), Raw: b[:b[0]]}
+	return a, nil
+}
+
+func parseAddrs(attrs uint, fn func(int, []byte) (int, Addr, error), b []byte) ([]Addr, error) {
+	var as [sysRTAX_MAX]Addr
+	af := int(sysAF_UNSPEC)
+	for i := uint(0); i < sysRTAX_MAX && len(b) >= roundup(0); i++ {
+		if attrs&(1<<i) == 0 {
+			continue
+		}
+		if i <= sysRTAX_BRD {
+			switch b[1] {
+			case sysAF_LINK:
+				a, err := parseLinkAddr(b)
+				if err != nil {
+					return nil, err
+				}
+				as[i] = a
+				b = b[roundup(int(b[0])):]
+			case sysAF_INET, sysAF_INET6:
+				af = int(b[1])
+				a, err := parseInetAddr(af, b)
+				if err != nil {
+					return nil, err
+				}
+				as[i] = a
+				b = b[roundup(int(b[0])):]
+			default:
+				l, a, err := fn(af, b)
+				if err != nil {
+					return nil, err
+				}
+				as[i] = a
+				ll := roundup(l)
+				if len(b) < ll {
+					b = b[l:]
+				} else {
+					b = b[ll:]
+				}
+			}
+		} else {
+			a, err := parseDefaultAddr(b)
+			if err != nil {
+				return nil, err
+			}
+			as[i] = a
+			b = b[roundup(int(b[0])):]
+		}
+	}
+	return as[:], nil
+}
diff --git a/libgo/go/golang_org/x/net/route/address_darwin_test.go b/libgo/go/golang_org/x/net/route/address_darwin_test.go
new file mode 100644
index 00000000000..b86bd3df1f8
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/address_darwin_test.go
@@ -0,0 +1,63 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+import (
+	"reflect"
+	"testing"
+)
+
+type parseAddrsOnDarwinTest struct {
+	attrs uint
+	fn    func(int, []byte) (int, Addr, error)
+	b     []byte
+	as    []Addr
+}
+
+var parseAddrsOnDarwinLittleEndianTests = []parseAddrsOnDarwinTest{
+	{
+		sysRTA_DST | sysRTA_GATEWAY | sysRTA_NETMASK,
+		parseKernelInetAddr,
+		[]byte{
+			0x10, 0x2, 0x0, 0x0, 0xc0, 0xa8, 0x56, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+
+			0x14, 0x12, 0x4, 0x0, 0x6, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0,
+
+			0x7, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+		},
+		[]Addr{
+			&Inet4Addr{IP: [4]byte{192, 168, 86, 0}},
+			&LinkAddr{Index: 4},
+			&Inet4Addr{IP: [4]byte{255, 255, 255, 255}},
+			nil,
+			nil,
+			nil,
+			nil,
+			nil,
+		},
+	},
+}
+
+func TestParseAddrsOnDarwin(t *testing.T) {
+	tests := parseAddrsOnDarwinLittleEndianTests
+	if nativeEndian != littleEndian {
+		t.Skip("no test for non-little endian machine yet")
+	}
+
+	for i, tt := range tests {
+		as, err := parseAddrs(tt.attrs, tt.fn, tt.b)
+		if err != nil {
+			t.Error(i, err)
+			continue
+		}
+		if !reflect.DeepEqual(as, tt.as) {
+			t.Errorf("#%d: got %+v; want %+v", i, as, tt.as)
+			continue
+		}
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/address_test.go b/libgo/go/golang_org/x/net/route/address_test.go
new file mode 100644
index 00000000000..2005ef7c20c
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/address_test.go
@@ -0,0 +1,103 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+import (
+	"reflect"
+	"testing"
+)
+
+type parseAddrsTest struct {
+	attrs uint
+	fn    func(int, []byte) (int, Addr, error)
+	b     []byte
+	as    []Addr
+}
+
+var parseAddrsLittleEndianTests = []parseAddrsTest{
+	{
+		sysRTA_DST | sysRTA_GATEWAY | sysRTA_NETMASK | sysRTA_BRD,
+		parseKernelInetAddr,
+		[]byte{
+			0x38, 0x12, 0x0, 0x0, 0xff, 0xff, 0xff, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+
+			0x38, 0x12, 0x2, 0x0, 0x6, 0x3, 0x6, 0x0,
+			0x65, 0x6d, 0x31, 0x0, 0xc, 0x29, 0x66, 0x2c,
+			0xdc, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+
+			0x10, 0x2, 0x0, 0x0, 0xac, 0x10, 0xdc, 0xb4,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+
+			0x10, 0x2, 0x0, 0x0, 0xac, 0x10, 0xdc, 0xff,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+		},
+		[]Addr{
+			&LinkAddr{Index: 0},
+			&LinkAddr{Index: 2, Name: "em1", Addr: []byte{0x00, 0x0c, 0x29, 0x66, 0x2c, 0xdc}},
+			&Inet4Addr{IP: [4]byte{172, 16, 220, 180}},
+			nil,
+			nil,
+			nil,
+			nil,
+			&Inet4Addr{IP: [4]byte{172, 16, 220, 255}},
+		},
+	},
+	{
+		sysRTA_NETMASK | sysRTA_IFP | sysRTA_IFA,
+		parseKernelInetAddr,
+		[]byte{
+			0x7, 0x0, 0x0, 0x0, 0xff, 0xff, 0xff, 0x0,
+
+			0x18, 0x12, 0xa, 0x0, 0x87, 0x8, 0x0, 0x0,
+			0x76, 0x6c, 0x61, 0x6e, 0x35, 0x36, 0x38, 0x32,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+
+			0x10, 0x2, 0x0, 0x0, 0xa9, 0xfe, 0x0, 0x1,
+			0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+		},
+		[]Addr{
+			nil,
+			nil,
+			&Inet4Addr{IP: [4]byte{255, 255, 255, 0}},
+			nil,
+			&LinkAddr{Index: 10, Name: "vlan5682"},
+			&Inet4Addr{IP: [4]byte{169, 254, 0, 1}},
+			nil,
+			nil,
+		},
+	},
+}
+
+func TestParseAddrs(t *testing.T) {
+	tests := parseAddrsLittleEndianTests
+	if nativeEndian != littleEndian {
+		t.Skip("no test for non-little endian machine yet")
+	}
+
+	for i, tt := range tests {
+		as, err := parseAddrs(tt.attrs, tt.fn, tt.b)
+		if err != nil {
+			t.Error(i, err)
+			continue
+		}
+		as = as[:8] // the list varies between operating systems
+		if !reflect.DeepEqual(as, tt.as) {
+			t.Errorf("#%d: got %+v; want %+v", i, as, tt.as)
+			continue
+		}
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/binary.go b/libgo/go/golang_org/x/net/route/binary.go
new file mode 100644
index 00000000000..4c561631b94
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/binary.go
@@ -0,0 +1,90 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+// This file contains duplicates of encoding/binary package.
+//
+// This package is supposed to be used by the net package of standard
+// library. Therefore a package set used in the package must be the
+// same as net package.
+
+var (
+	littleEndian binaryLittleEndian
+	bigEndian    binaryBigEndian
+)
+
+type binaryByteOrder interface {
+	Uint16([]byte) uint16
+	Uint32([]byte) uint32
+	PutUint16([]byte, uint16)
+	PutUint32([]byte, uint32)
+	Uint64([]byte) uint64
+}
+
+type binaryLittleEndian struct{}
+
+func (binaryLittleEndian) Uint16(b []byte) uint16 {
+	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint16(b[0]) | uint16(b[1])<<8
+}
+
+func (binaryLittleEndian) PutUint16(b []byte, v uint16) {
+	_ = b[1] // early bounds check to guarantee safety of writes below
+	b[0] = byte(v)
+	b[1] = byte(v >> 8)
+}
+
+func (binaryLittleEndian) Uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func (binaryLittleEndian) PutUint32(b []byte, v uint32) {
+	_ = b[3] // early bounds check to guarantee safety of writes below
+	b[0] = byte(v)
+	b[1] = byte(v >> 8)
+	b[2] = byte(v >> 16)
+	b[3] = byte(v >> 24)
+}
+
+func (binaryLittleEndian) Uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+type binaryBigEndian struct{}
+
+func (binaryBigEndian) Uint16(b []byte) uint16 {
+	_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint16(b[1]) | uint16(b[0])<<8
+}
+
+func (binaryBigEndian) PutUint16(b []byte, v uint16) {
+	_ = b[1] // early bounds check to guarantee safety of writes below
+	b[0] = byte(v >> 8)
+	b[1] = byte(v)
+}
+
+func (binaryBigEndian) Uint32(b []byte) uint32 {
+	_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+}
+
+func (binaryBigEndian) PutUint32(b []byte, v uint32) {
+	_ = b[3] // early bounds check to guarantee safety of writes below
+	b[0] = byte(v >> 24)
+	b[1] = byte(v >> 16)
+	b[2] = byte(v >> 8)
+	b[3] = byte(v)
+}
+
+func (binaryBigEndian) Uint64(b []byte) uint64 {
+	_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
+	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
+		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
+}
diff --git a/libgo/go/golang_org/x/net/route/defs_darwin.go b/libgo/go/golang_org/x/net/route/defs_darwin.go
new file mode 100644
index 00000000000..f452ad14ce6
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/defs_darwin.go
@@ -0,0 +1,106 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package route
+
+/*
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+*/
+import "C"
+
+const (
+	sysAF_UNSPEC = C.AF_UNSPEC
+	sysAF_INET   = C.AF_INET
+	sysAF_ROUTE  = C.AF_ROUTE
+	sysAF_LINK   = C.AF_LINK
+	sysAF_INET6  = C.AF_INET6
+
+	sysNET_RT_DUMP    = C.NET_RT_DUMP
+	sysNET_RT_FLAGS   = C.NET_RT_FLAGS
+	sysNET_RT_IFLIST  = C.NET_RT_IFLIST
+	sysNET_RT_STAT    = C.NET_RT_STAT
+	sysNET_RT_TRASH   = C.NET_RT_TRASH
+	sysNET_RT_IFLIST2 = C.NET_RT_IFLIST2
+	sysNET_RT_DUMP2   = C.NET_RT_DUMP2
+	sysNET_RT_MAXID   = C.NET_RT_MAXID
+)
+
+const (
+	sysCTL_MAXNAME = C.CTL_MAXNAME
+
+	sysCTL_UNSPEC  = C.CTL_UNSPEC
+	sysCTL_KERN    = C.CTL_KERN
+	sysCTL_VM      = C.CTL_VM
+	sysCTL_VFS     = C.CTL_VFS
+	sysCTL_NET     = C.CTL_NET
+	sysCTL_DEBUG   = C.CTL_DEBUG
+	sysCTL_HW      = C.CTL_HW
+	sysCTL_MACHDEP = C.CTL_MACHDEP
+	sysCTL_USER    = C.CTL_USER
+	sysCTL_MAXID   = C.CTL_MAXID
+)
+
+const (
+	sysRTM_VERSION = C.RTM_VERSION
+
+	sysRTM_ADD       = C.RTM_ADD
+	sysRTM_DELETE    = C.RTM_DELETE
+	sysRTM_CHANGE    = C.RTM_CHANGE
+	sysRTM_GET       = C.RTM_GET
+	sysRTM_LOSING    = C.RTM_LOSING
+	sysRTM_REDIRECT  = C.RTM_REDIRECT
+	sysRTM_MISS      = C.RTM_MISS
+	sysRTM_LOCK      = C.RTM_LOCK
+	sysRTM_OLDADD    = C.RTM_OLDADD
+	sysRTM_OLDDEL    = C.RTM_OLDDEL
+	sysRTM_RESOLVE   = C.RTM_RESOLVE
+	sysRTM_NEWADDR   = C.RTM_NEWADDR
+	sysRTM_DELADDR   = C.RTM_DELADDR
+	sysRTM_IFINFO    = C.RTM_IFINFO
+	sysRTM_NEWMADDR  = C.RTM_NEWMADDR
+	sysRTM_DELMADDR  = C.RTM_DELMADDR
+	sysRTM_IFINFO2   = C.RTM_IFINFO2
+	sysRTM_NEWMADDR2 = C.RTM_NEWMADDR2
+	sysRTM_GET2      = C.RTM_GET2
+
+	sysRTA_DST     = C.RTA_DST
+	sysRTA_GATEWAY = C.RTA_GATEWAY
+	sysRTA_NETMASK = C.RTA_NETMASK
+	sysRTA_GENMASK = C.RTA_GENMASK
+	sysRTA_IFP     = C.RTA_IFP
+	sysRTA_IFA     = C.RTA_IFA
+	sysRTA_AUTHOR  = C.RTA_AUTHOR
+	sysRTA_BRD     = C.RTA_BRD
+
+	sysRTAX_DST     = C.RTAX_DST
+	sysRTAX_GATEWAY = C.RTAX_GATEWAY
+	sysRTAX_NETMASK = C.RTAX_NETMASK
+	sysRTAX_GENMASK = C.RTAX_GENMASK
+	sysRTAX_IFP     = C.RTAX_IFP
+	sysRTAX_IFA     = C.RTAX_IFA
+	sysRTAX_AUTHOR  = C.RTAX_AUTHOR
+	sysRTAX_BRD     = C.RTAX_BRD
+	sysRTAX_MAX     = C.RTAX_MAX
+)
+
+const (
+	sizeofIfMsghdrDarwin15    = C.sizeof_struct_if_msghdr
+	sizeofIfaMsghdrDarwin15   = C.sizeof_struct_ifa_msghdr
+	sizeofIfmaMsghdrDarwin15  = C.sizeof_struct_ifma_msghdr
+	sizeofIfMsghdr2Darwin15   = C.sizeof_struct_if_msghdr2
+	sizeofIfmaMsghdr2Darwin15 = C.sizeof_struct_ifma_msghdr2
+	sizeofIfDataDarwin15      = C.sizeof_struct_if_data
+	sizeofIfData64Darwin15    = C.sizeof_struct_if_data64
+
+	sizeofRtMsghdrDarwin15  = C.sizeof_struct_rt_msghdr
+	sizeofRtMsghdr2Darwin15 = C.sizeof_struct_rt_msghdr2
+	sizeofRtMetricsDarwin15 = C.sizeof_struct_rt_metrics
+)
diff --git a/libgo/go/golang_org/x/net/route/defs_dragonfly.go b/libgo/go/golang_org/x/net/route/defs_dragonfly.go
new file mode 100644
index 00000000000..c737751d76d
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/defs_dragonfly.go
@@ -0,0 +1,105 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package route
+
+/*
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+*/
+import "C"
+
+const (
+	sysAF_UNSPEC = C.AF_UNSPEC
+	sysAF_INET   = C.AF_INET
+	sysAF_ROUTE  = C.AF_ROUTE
+	sysAF_LINK   = C.AF_LINK
+	sysAF_INET6  = C.AF_INET6
+
+	sysNET_RT_DUMP   = C.NET_RT_DUMP
+	sysNET_RT_FLAGS  = C.NET_RT_FLAGS
+	sysNET_RT_IFLIST = C.NET_RT_IFLIST
+	sysNET_RT_MAXID  = C.NET_RT_MAXID
+)
+
+const (
+	sysCTL_MAXNAME = C.CTL_MAXNAME
+
+	sysCTL_UNSPEC   = C.CTL_UNSPEC
+	sysCTL_KERN     = C.CTL_KERN
+	sysCTL_VM       = C.CTL_VM
+	sysCTL_VFS      = C.CTL_VFS
+	sysCTL_NET      = C.CTL_NET
+	sysCTL_DEBUG    = C.CTL_DEBUG
+	sysCTL_HW       = C.CTL_HW
+	sysCTL_MACHDEP  = C.CTL_MACHDEP
+	sysCTL_USER     = C.CTL_USER
+	sysCTL_P1003_1B = C.CTL_P1003_1B
+	sysCTL_LWKT     = C.CTL_LWKT
+	sysCTL_MAXID    = C.CTL_MAXID
+)
+
+const (
+	sysRTM_VERSION = C.RTM_VERSION
+
+	sysRTM_ADD        = C.RTM_ADD
+	sysRTM_DELETE     = C.RTM_DELETE
+	sysRTM_CHANGE     = C.RTM_CHANGE
+	sysRTM_GET        = C.RTM_GET
+	sysRTM_LOSING     = C.RTM_LOSING
+	sysRTM_REDIRECT   = C.RTM_REDIRECT
+	sysRTM_MISS       = C.RTM_MISS
+	sysRTM_LOCK       = C.RTM_LOCK
+	sysRTM_OLDADD     = C.RTM_OLDADD
+	sysRTM_OLDDEL     = C.RTM_OLDDEL
+	sysRTM_RESOLVE    = C.RTM_RESOLVE
+	sysRTM_NEWADDR    = C.RTM_NEWADDR
+	sysRTM_DELADDR    = C.RTM_DELADDR
+	sysRTM_IFINFO     = C.RTM_IFINFO
+	sysRTM_NEWMADDR   = C.RTM_NEWMADDR
+	sysRTM_DELMADDR   = C.RTM_DELMADDR
+	sysRTM_IFANNOUNCE = C.RTM_IFANNOUNCE
+	sysRTM_IEEE80211  = C.RTM_IEEE80211
+
+	sysRTA_DST     = C.RTA_DST
+	sysRTA_GATEWAY = C.RTA_GATEWAY
+	sysRTA_NETMASK = C.RTA_NETMASK
+	sysRTA_GENMASK = C.RTA_GENMASK
+	sysRTA_IFP     = C.RTA_IFP
+	sysRTA_IFA     = C.RTA_IFA
+	sysRTA_AUTHOR  = C.RTA_AUTHOR
+	sysRTA_BRD     = C.RTA_BRD
+	sysRTA_MPLS1   = C.RTA_MPLS1
+	sysRTA_MPLS2   = C.RTA_MPLS2
+	sysRTA_MPLS3   = C.RTA_MPLS3
+
+	sysRTAX_DST     = C.RTAX_DST
+	sysRTAX_GATEWAY = C.RTAX_GATEWAY
+	sysRTAX_NETMASK = C.RTAX_NETMASK
+	sysRTAX_GENMASK = C.RTAX_GENMASK
+	sysRTAX_IFP     = C.RTAX_IFP
+	sysRTAX_IFA     = C.RTAX_IFA
+	sysRTAX_AUTHOR  = C.RTAX_AUTHOR
+	sysRTAX_BRD     = C.RTAX_BRD
+	sysRTAX_MPLS1   = C.RTAX_MPLS1
+	sysRTAX_MPLS2   = C.RTAX_MPLS2
+	sysRTAX_MPLS3   = C.RTAX_MPLS3
+	sysRTAX_MAX     = C.RTAX_MAX
+)
+
+const (
+	sizeofIfMsghdrDragonFlyBSD4         = C.sizeof_struct_if_msghdr
+	sizeofIfaMsghdrDragonFlyBSD4        = C.sizeof_struct_ifa_msghdr
+	sizeofIfmaMsghdrDragonFlyBSD4       = C.sizeof_struct_ifma_msghdr
+	sizeofIfAnnouncemsghdrDragonFlyBSD4 = C.sizeof_struct_if_announcemsghdr
+
+	sizeofRtMsghdrDragonFlyBSD4  = C.sizeof_struct_rt_msghdr
+	sizeofRtMetricsDragonFlyBSD4 = C.sizeof_struct_rt_metrics
+)
diff --git a/libgo/go/golang_org/x/net/route/defs_freebsd.go b/libgo/go/golang_org/x/net/route/defs_freebsd.go
new file mode 100644
index 00000000000..8f834e81db5
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/defs_freebsd.go
@@ -0,0 +1,329 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package route
+
+/*
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+
+struct if_data_freebsd7 {
+	u_char ifi_type;
+	u_char ifi_physical;
+	u_char ifi_addrlen;
+	u_char ifi_hdrlen;
+	u_char ifi_link_state;
+	u_char ifi_spare_char1;
+	u_char ifi_spare_char2;
+	u_char ifi_datalen;
+	u_long ifi_mtu;
+	u_long ifi_metric;
+	u_long ifi_baudrate;
+	u_long ifi_ipackets;
+	u_long ifi_ierrors;
+	u_long ifi_opackets;
+	u_long ifi_oerrors;
+	u_long ifi_collisions;
+	u_long ifi_ibytes;
+	u_long ifi_obytes;
+	u_long ifi_imcasts;
+	u_long ifi_omcasts;
+	u_long ifi_iqdrops;
+	u_long ifi_noproto;
+	u_long ifi_hwassist;
+	time_t __ifi_epoch;
+	struct timeval __ifi_lastchange;
+};
+
+struct if_data_freebsd8 {
+	u_char ifi_type;
+	u_char ifi_physical;
+	u_char ifi_addrlen;
+	u_char ifi_hdrlen;
+	u_char ifi_link_state;
+	u_char ifi_spare_char1;
+	u_char ifi_spare_char2;
+	u_char ifi_datalen;
+	u_long ifi_mtu;
+	u_long ifi_metric;
+	u_long ifi_baudrate;
+	u_long ifi_ipackets;
+	u_long ifi_ierrors;
+	u_long ifi_opackets;
+	u_long ifi_oerrors;
+	u_long ifi_collisions;
+	u_long ifi_ibytes;
+	u_long ifi_obytes;
+	u_long ifi_imcasts;
+	u_long ifi_omcasts;
+	u_long ifi_iqdrops;
+	u_long ifi_noproto;
+	u_long ifi_hwassist;
+	time_t __ifi_epoch;
+	struct timeval __ifi_lastchange;
+};
+
+struct if_data_freebsd9 {
+	u_char ifi_type;
+	u_char ifi_physical;
+	u_char ifi_addrlen;
+	u_char ifi_hdrlen;
+	u_char ifi_link_state;
+	u_char ifi_spare_char1;
+	u_char ifi_spare_char2;
+	u_char ifi_datalen;
+	u_long ifi_mtu;
+	u_long ifi_metric;
+	u_long ifi_baudrate;
+	u_long ifi_ipackets;
+	u_long ifi_ierrors;
+	u_long ifi_opackets;
+	u_long ifi_oerrors;
+	u_long ifi_collisions;
+	u_long ifi_ibytes;
+	u_long ifi_obytes;
+	u_long ifi_imcasts;
+	u_long ifi_omcasts;
+	u_long ifi_iqdrops;
+	u_long ifi_noproto;
+	u_long ifi_hwassist;
+	time_t __ifi_epoch;
+	struct timeval __ifi_lastchange;
+};
+
+struct if_data_freebsd10 {
+	u_char ifi_type;
+	u_char ifi_physical;
+	u_char ifi_addrlen;
+	u_char ifi_hdrlen;
+	u_char ifi_link_state;
+	u_char ifi_vhid;
+	u_char ifi_baudrate_pf;
+	u_char ifi_datalen;
+	u_long ifi_mtu;
+	u_long ifi_metric;
+	u_long ifi_baudrate;
+	u_long ifi_ipackets;
+	u_long ifi_ierrors;
+	u_long ifi_opackets;
+	u_long ifi_oerrors;
+	u_long ifi_collisions;
+	u_long ifi_ibytes;
+	u_long ifi_obytes;
+	u_long ifi_imcasts;
+	u_long ifi_omcasts;
+	u_long ifi_iqdrops;
+	u_long ifi_noproto;
+	uint64_t ifi_hwassist;
+	time_t __ifi_epoch;
+	struct timeval __ifi_lastchange;
+};
+
+struct if_data_freebsd11 {
+	uint8_t ifi_type;
+	uint8_t ifi_physical;
+	uint8_t ifi_addrlen;
+	uint8_t ifi_hdrlen;
+	uint8_t ifi_link_state;
+	uint8_t ifi_vhid;
+	uint16_t ifi_datalen;
+	uint32_t ifi_mtu;
+	uint32_t ifi_metric;
+	uint64_t ifi_baudrate;
+	uint64_t ifi_ipackets;
+	uint64_t ifi_ierrors;
+	uint64_t ifi_opackets;
+	uint64_t ifi_oerrors;
+	uint64_t ifi_collisions;
+	uint64_t ifi_ibytes;
+	uint64_t ifi_obytes;
+	uint64_t ifi_imcasts;
+	uint64_t ifi_omcasts;
+	uint64_t ifi_iqdrops;
+	uint64_t ifi_oqdrops;
+	uint64_t ifi_noproto;
+	uint64_t ifi_hwassist;
+	union {
+		time_t tt;
+		uint64_t ph;
+	} __ifi_epoch;
+	union {
+		struct timeval tv;
+		struct {
+			uint64_t ph1;
+			uint64_t ph2;
+		} ph;
+	} __ifi_lastchange;
+};
+
+struct if_msghdr_freebsd7 {
+	u_short ifm_msglen;
+	u_char ifm_version;
+	u_char ifm_type;
+	int ifm_addrs;
+	int ifm_flags;
+	u_short ifm_index;
+	struct if_data_freebsd7 ifm_data;
+};
+
+struct if_msghdr_freebsd8 {
+	u_short ifm_msglen;
+	u_char ifm_version;
+	u_char ifm_type;
+	int ifm_addrs;
+	int ifm_flags;
+	u_short ifm_index;
+	struct if_data_freebsd8 ifm_data;
+};
+
+struct if_msghdr_freebsd9 {
+	u_short ifm_msglen;
+	u_char ifm_version;
+	u_char ifm_type;
+	int ifm_addrs;
+	int ifm_flags;
+	u_short ifm_index;
+	struct if_data_freebsd9 ifm_data;
+};
+
+struct if_msghdr_freebsd10 {
+	u_short ifm_msglen;
+	u_char ifm_version;
+	u_char ifm_type;
+	int ifm_addrs;
+	int ifm_flags;
+	u_short ifm_index;
+	struct if_data_freebsd10 ifm_data;
+};
+
+struct if_msghdr_freebsd11 {
+	u_short ifm_msglen;
+	u_char ifm_version;
+	u_char ifm_type;
+	int ifm_addrs;
+	int ifm_flags;
+	u_short ifm_index;
+	struct if_data_freebsd11 ifm_data;
+};
+*/
+import "C"
+
+const (
+	sysAF_UNSPEC = C.AF_UNSPEC
+	sysAF_INET   = C.AF_INET
+	sysAF_ROUTE  = C.AF_ROUTE
+	sysAF_LINK   = C.AF_LINK
+	sysAF_INET6  = C.AF_INET6
+
+	sysNET_RT_DUMP     = C.NET_RT_DUMP
+	sysNET_RT_FLAGS    = C.NET_RT_FLAGS
+	sysNET_RT_IFLIST   = C.NET_RT_IFLIST
+	sysNET_RT_IFMALIST = C.NET_RT_IFMALIST
+	sysNET_RT_IFLISTL  = C.NET_RT_IFLISTL
+)
+
+const (
+	sysCTL_MAXNAME = C.CTL_MAXNAME
+
+	sysCTL_UNSPEC   = C.CTL_UNSPEC
+	sysCTL_KERN     = C.CTL_KERN
+	sysCTL_VM       = C.CTL_VM
+	sysCTL_VFS      = C.CTL_VFS
+	sysCTL_NET      = C.CTL_NET
+	sysCTL_DEBUG    = C.CTL_DEBUG
+	sysCTL_HW       = C.CTL_HW
+	sysCTL_MACHDEP  = C.CTL_MACHDEP
+	sysCTL_USER     = C.CTL_USER
+	sysCTL_P1003_1B = C.CTL_P1003_1B
+)
+
+const (
+	sysRTM_VERSION = C.RTM_VERSION
+
+	sysRTM_ADD        = C.RTM_ADD
+	sysRTM_DELETE     = C.RTM_DELETE
+	sysRTM_CHANGE     = C.RTM_CHANGE
+	sysRTM_GET        = C.RTM_GET
+	sysRTM_LOSING     = C.RTM_LOSING
+	sysRTM_REDIRECT   = C.RTM_REDIRECT
+	sysRTM_MISS       = C.RTM_MISS
+	sysRTM_LOCK       = C.RTM_LOCK
+	sysRTM_RESOLVE    = C.RTM_RESOLVE
+	sysRTM_NEWADDR    = C.RTM_NEWADDR
+	sysRTM_DELADDR    = C.RTM_DELADDR
+	sysRTM_IFINFO     = C.RTM_IFINFO
+	sysRTM_NEWMADDR   = C.RTM_NEWMADDR
+	sysRTM_DELMADDR   = C.RTM_DELMADDR
+	sysRTM_IFANNOUNCE = C.RTM_IFANNOUNCE
+	sysRTM_IEEE80211  = C.RTM_IEEE80211
+
+	sysRTA_DST     = C.RTA_DST
+	sysRTA_GATEWAY = C.RTA_GATEWAY
+	sysRTA_NETMASK = C.RTA_NETMASK
+	sysRTA_GENMASK = C.RTA_GENMASK
+	sysRTA_IFP     = C.RTA_IFP
+	sysRTA_IFA     = C.RTA_IFA
+	sysRTA_AUTHOR  = C.RTA_AUTHOR
+	sysRTA_BRD     = C.RTA_BRD
+
+	sysRTAX_DST     = C.RTAX_DST
+	sysRTAX_GATEWAY = C.RTAX_GATEWAY
+	sysRTAX_NETMASK = C.RTAX_NETMASK
+	sysRTAX_GENMASK = C.RTAX_GENMASK
+	sysRTAX_IFP     = C.RTAX_IFP
+	sysRTAX_IFA     = C.RTAX_IFA
+	sysRTAX_AUTHOR  = C.RTAX_AUTHOR
+	sysRTAX_BRD     = C.RTAX_BRD
+	sysRTAX_MAX     = C.RTAX_MAX
+)
+
+const (
+	sizeofIfMsghdrlFreeBSD10        = C.sizeof_struct_if_msghdrl
+	sizeofIfaMsghdrFreeBSD10        = C.sizeof_struct_ifa_msghdr
+	sizeofIfaMsghdrlFreeBSD10       = C.sizeof_struct_ifa_msghdrl
+	sizeofIfmaMsghdrFreeBSD10       = C.sizeof_struct_ifma_msghdr
+	sizeofIfAnnouncemsghdrFreeBSD10 = C.sizeof_struct_if_announcemsghdr
+
+	sizeofRtMsghdrFreeBSD10  = C.sizeof_struct_rt_msghdr
+	sizeofRtMetricsFreeBSD10 = C.sizeof_struct_rt_metrics
+
+	sizeofIfMsghdrFreeBSD7  = C.sizeof_struct_if_msghdr_freebsd7
+	sizeofIfMsghdrFreeBSD8  = C.sizeof_struct_if_msghdr_freebsd8
+	sizeofIfMsghdrFreeBSD9  = C.sizeof_struct_if_msghdr_freebsd9
+	sizeofIfMsghdrFreeBSD10 = C.sizeof_struct_if_msghdr_freebsd10
+	sizeofIfMsghdrFreeBSD11 = C.sizeof_struct_if_msghdr_freebsd11
+
+	sizeofIfDataFreeBSD7  = C.sizeof_struct_if_data_freebsd7
+	sizeofIfDataFreeBSD8  = C.sizeof_struct_if_data_freebsd8
+	sizeofIfDataFreeBSD9  = C.sizeof_struct_if_data_freebsd9
+	sizeofIfDataFreeBSD10 = C.sizeof_struct_if_data_freebsd10
+	sizeofIfDataFreeBSD11 = C.sizeof_struct_if_data_freebsd11
+
+	sizeofIfMsghdrlFreeBSD10Emu        = C.sizeof_struct_if_msghdrl
+	sizeofIfaMsghdrFreeBSD10Emu        = C.sizeof_struct_ifa_msghdr
+	sizeofIfaMsghdrlFreeBSD10Emu       = C.sizeof_struct_ifa_msghdrl
+	sizeofIfmaMsghdrFreeBSD10Emu       = C.sizeof_struct_ifma_msghdr
+	sizeofIfAnnouncemsghdrFreeBSD10Emu = C.sizeof_struct_if_announcemsghdr
+
+	sizeofRtMsghdrFreeBSD10Emu  = C.sizeof_struct_rt_msghdr
+	sizeofRtMetricsFreeBSD10Emu = C.sizeof_struct_rt_metrics
+
+	sizeofIfMsghdrFreeBSD7Emu  = C.sizeof_struct_if_msghdr_freebsd7
+	sizeofIfMsghdrFreeBSD8Emu  = C.sizeof_struct_if_msghdr_freebsd8
+	sizeofIfMsghdrFreeBSD9Emu  = C.sizeof_struct_if_msghdr_freebsd9
+	sizeofIfMsghdrFreeBSD10Emu = C.sizeof_struct_if_msghdr_freebsd10
+	sizeofIfMsghdrFreeBSD11Emu = C.sizeof_struct_if_msghdr_freebsd11
+
+	sizeofIfDataFreeBSD7Emu  = C.sizeof_struct_if_data_freebsd7
+	sizeofIfDataFreeBSD8Emu  = C.sizeof_struct_if_data_freebsd8
+	sizeofIfDataFreeBSD9Emu  = C.sizeof_struct_if_data_freebsd9
+	sizeofIfDataFreeBSD10Emu = C.sizeof_struct_if_data_freebsd10
+	sizeofIfDataFreeBSD11Emu = C.sizeof_struct_if_data_freebsd11
+)
diff --git a/libgo/go/golang_org/x/net/route/defs_netbsd.go b/libgo/go/golang_org/x/net/route/defs_netbsd.go
new file mode 100644
index 00000000000..b18d85e0165
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/defs_netbsd.go
@@ -0,0 +1,104 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package route
+
+/*
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+*/
+import "C"
+
+const (
+	sysAF_UNSPEC = C.AF_UNSPEC
+	sysAF_INET   = C.AF_INET
+	sysAF_ROUTE  = C.AF_ROUTE
+	sysAF_LINK   = C.AF_LINK
+	sysAF_INET6  = C.AF_INET6
+
+	sysNET_RT_DUMP   = C.NET_RT_DUMP
+	sysNET_RT_FLAGS  = C.NET_RT_FLAGS
+	sysNET_RT_IFLIST = C.NET_RT_IFLIST
+	sysNET_RT_MAXID  = C.NET_RT_MAXID
+)
+
+const (
+	sysCTL_MAXNAME = C.CTL_MAXNAME
+
+	sysCTL_UNSPEC   = C.CTL_UNSPEC
+	sysCTL_KERN     = C.CTL_KERN
+	sysCTL_VM       = C.CTL_VM
+	sysCTL_VFS      = C.CTL_VFS
+	sysCTL_NET      = C.CTL_NET
+	sysCTL_DEBUG    = C.CTL_DEBUG
+	sysCTL_HW       = C.CTL_HW
+	sysCTL_MACHDEP  = C.CTL_MACHDEP
+	sysCTL_USER     = C.CTL_USER
+	sysCTL_DDB      = C.CTL_DDB
+	sysCTL_PROC     = C.CTL_PROC
+	sysCTL_VENDOR   = C.CTL_VENDOR
+	sysCTL_EMUL     = C.CTL_EMUL
+	sysCTL_SECURITY = C.CTL_SECURITY
+	sysCTL_MAXID    = C.CTL_MAXID
+)
+
+const (
+	sysRTM_VERSION = C.RTM_VERSION
+
+	sysRTM_ADD        = C.RTM_ADD
+	sysRTM_DELETE     = C.RTM_DELETE
+	sysRTM_CHANGE     = C.RTM_CHANGE
+	sysRTM_GET        = C.RTM_GET
+	sysRTM_LOSING     = C.RTM_LOSING
+	sysRTM_REDIRECT   = C.RTM_REDIRECT
+	sysRTM_MISS       = C.RTM_MISS
+	sysRTM_LOCK       = C.RTM_LOCK
+	sysRTM_OLDADD     = C.RTM_OLDADD
+	sysRTM_OLDDEL     = C.RTM_OLDDEL
+	sysRTM_RESOLVE    = C.RTM_RESOLVE
+	sysRTM_NEWADDR    = C.RTM_NEWADDR
+	sysRTM_DELADDR    = C.RTM_DELADDR
+	sysRTM_IFANNOUNCE = C.RTM_IFANNOUNCE
+	sysRTM_IEEE80211  = C.RTM_IEEE80211
+	sysRTM_SETGATE    = C.RTM_SETGATE
+	sysRTM_LLINFO_UPD = C.RTM_LLINFO_UPD
+	sysRTM_IFINFO     = C.RTM_IFINFO
+	sysRTM_CHGADDR    = C.RTM_CHGADDR
+
+	sysRTA_DST     = C.RTA_DST
+	sysRTA_GATEWAY = C.RTA_GATEWAY
+	sysRTA_NETMASK = C.RTA_NETMASK
+	sysRTA_GENMASK = C.RTA_GENMASK
+	sysRTA_IFP     = C.RTA_IFP
+	sysRTA_IFA     = C.RTA_IFA
+	sysRTA_AUTHOR  = C.RTA_AUTHOR
+	sysRTA_BRD     = C.RTA_BRD
+	sysRTA_TAG     = C.RTA_TAG
+
+	sysRTAX_DST     = C.RTAX_DST
+	sysRTAX_GATEWAY = C.RTAX_GATEWAY
+	sysRTAX_NETMASK = C.RTAX_NETMASK
+	sysRTAX_GENMASK = C.RTAX_GENMASK
+	sysRTAX_IFP     = C.RTAX_IFP
+	sysRTAX_IFA     = C.RTAX_IFA
+	sysRTAX_AUTHOR  = C.RTAX_AUTHOR
+	sysRTAX_BRD     = C.RTAX_BRD
+	sysRTAX_TAG     = C.RTAX_TAG
+	sysRTAX_MAX     = C.RTAX_MAX
+)
+
+const (
+	sizeofIfMsghdrNetBSD7         = C.sizeof_struct_if_msghdr
+	sizeofIfaMsghdrNetBSD7        = C.sizeof_struct_ifa_msghdr
+	sizeofIfAnnouncemsghdrNetBSD7 = C.sizeof_struct_if_announcemsghdr
+
+	sizeofRtMsghdrNetBSD7  = C.sizeof_struct_rt_msghdr
+	sizeofRtMetricsNetBSD7 = C.sizeof_struct_rt_metrics
+)
diff --git a/libgo/go/golang_org/x/net/route/defs_openbsd.go b/libgo/go/golang_org/x/net/route/defs_openbsd.go
new file mode 100644
index 00000000000..5df7a43bc3e
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/defs_openbsd.go
@@ -0,0 +1,93 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package route
+
+/*
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/route.h>
+*/
+import "C"
+
+const (
+	sysAF_UNSPEC = C.AF_UNSPEC
+	sysAF_INET   = C.AF_INET
+	sysAF_ROUTE  = C.AF_ROUTE
+	sysAF_LINK   = C.AF_LINK
+	sysAF_INET6  = C.AF_INET6
+
+	sysNET_RT_DUMP    = C.NET_RT_DUMP
+	sysNET_RT_FLAGS   = C.NET_RT_FLAGS
+	sysNET_RT_IFLIST  = C.NET_RT_IFLIST
+	sysNET_RT_STATS   = C.NET_RT_STATS
+	sysNET_RT_TABLE   = C.NET_RT_TABLE
+	sysNET_RT_IFNAMES = C.NET_RT_IFNAMES
+	sysNET_RT_MAXID   = C.NET_RT_MAXID
+)
+
+const (
+	sysCTL_MAXNAME = C.CTL_MAXNAME
+
+	sysCTL_UNSPEC  = C.CTL_UNSPEC
+	sysCTL_KERN    = C.CTL_KERN
+	sysCTL_VM      = C.CTL_VM
+	sysCTL_FS      = C.CTL_FS
+	sysCTL_NET     = C.CTL_NET
+	sysCTL_DEBUG   = C.CTL_DEBUG
+	sysCTL_HW      = C.CTL_HW
+	sysCTL_MACHDEP = C.CTL_MACHDEP
+	sysCTL_DDB     = C.CTL_DDB
+	sysCTL_VFS     = C.CTL_VFS
+	sysCTL_MAXID   = C.CTL_MAXID
+)
+
+const (
+	sysRTM_VERSION = C.RTM_VERSION
+
+	sysRTM_ADD        = C.RTM_ADD
+	sysRTM_DELETE     = C.RTM_DELETE
+	sysRTM_CHANGE     = C.RTM_CHANGE
+	sysRTM_GET        = C.RTM_GET
+	sysRTM_LOSING     = C.RTM_LOSING
+	sysRTM_REDIRECT   = C.RTM_REDIRECT
+	sysRTM_MISS       = C.RTM_MISS
+	sysRTM_LOCK       = C.RTM_LOCK
+	sysRTM_RESOLVE    = C.RTM_RESOLVE
+	sysRTM_NEWADDR    = C.RTM_NEWADDR
+	sysRTM_DELADDR    = C.RTM_DELADDR
+	sysRTM_IFINFO     = C.RTM_IFINFO
+	sysRTM_IFANNOUNCE = C.RTM_IFANNOUNCE
+	sysRTM_DESYNC     = C.RTM_DESYNC
+
+	sysRTA_DST     = C.RTA_DST
+	sysRTA_GATEWAY = C.RTA_GATEWAY
+	sysRTA_NETMASK = C.RTA_NETMASK
+	sysRTA_GENMASK = C.RTA_GENMASK
+	sysRTA_IFP     = C.RTA_IFP
+	sysRTA_IFA     = C.RTA_IFA
+	sysRTA_AUTHOR  = C.RTA_AUTHOR
+	sysRTA_BRD     = C.RTA_BRD
+	sysRTA_SRC     = C.RTA_SRC
+	sysRTA_SRCMASK = C.RTA_SRCMASK
+	sysRTA_LABEL   = C.RTA_LABEL
+
+	sysRTAX_DST     = C.RTAX_DST
+	sysRTAX_GATEWAY = C.RTAX_GATEWAY
+	sysRTAX_NETMASK = C.RTAX_NETMASK
+	sysRTAX_GENMASK = C.RTAX_GENMASK
+	sysRTAX_IFP     = C.RTAX_IFP
+	sysRTAX_IFA     = C.RTAX_IFA
+	sysRTAX_AUTHOR  = C.RTAX_AUTHOR
+	sysRTAX_BRD     = C.RTAX_BRD
+	sysRTAX_SRC     = C.RTAX_SRC
+	sysRTAX_SRCMASK = C.RTAX_SRCMASK
+	sysRTAX_LABEL   = C.RTAX_LABEL
+	sysRTAX_MAX     = C.RTAX_MAX
+)
diff --git a/libgo/go/golang_org/x/net/route/interface.go b/libgo/go/golang_org/x/net/route/interface.go
new file mode 100644
index 00000000000..854906d9c42
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/interface.go
@@ -0,0 +1,64 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+// An InterfaceMessage represents an interface message.
+type InterfaceMessage struct {
+	Version int    // message version
+	Type    int    // message type
+	Flags   int    // interface flags
+	Index   int    // interface index
+	Name    string // interface name
+	Addrs   []Addr // addresses
+
+	extOff int    // offset of header extension
+	raw    []byte // raw message
+}
+
+// An InterfaceAddrMessage represents an interface address message.
+type InterfaceAddrMessage struct {
+	Version int    // message version
+	Type    int    // message type
+	Flags   int    // interface flags
+	Index   int    // interface index
+	Addrs   []Addr // addresses
+
+	raw []byte // raw message
+}
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceAddrMessage) Sys() []Sys { return nil }
+
+// An InterfaceMulticastAddrMessage represents an interface multicast
+// address message.
+type InterfaceMulticastAddrMessage struct {
+	Version int    // message version
+	Type    int    // messsage type
+	Flags   int    // interface flags
+	Index   int    // interface index
+	Addrs   []Addr // addresses
+
+	raw []byte // raw message
+}
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceMulticastAddrMessage) Sys() []Sys { return nil }
+
+// An InterfaceAnnounceMessage represents an interface announcement
+// message.
+type InterfaceAnnounceMessage struct {
+	Version int    // message version
+	Type    int    // message type
+	Index   int    // interface index
+	Name    string // interface name
+	What    int    // what type of announcement
+
+	raw []byte // raw message
+}
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceAnnounceMessage) Sys() []Sys { return nil }
diff --git a/libgo/go/golang_org/x/net/route/interface_announce.go b/libgo/go/golang_org/x/net/route/interface_announce.go
new file mode 100644
index 00000000000..520d657b578
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/interface_announce.go
@@ -0,0 +1,32 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build dragonfly freebsd netbsd
+
+package route
+
+func (w *wireFormat) parseInterfaceAnnounceMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < w.bodyOff {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &InterfaceAnnounceMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Index:   int(nativeEndian.Uint16(b[4:6])),
+		What:    int(nativeEndian.Uint16(b[22:24])),
+		raw:     b[:l],
+	}
+	for i := 0; i < 16; i++ {
+		if b[6+i] != 0 {
+			continue
+		}
+		m.Name = string(b[6 : 6+i])
+		break
+	}
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/interface_classic.go b/libgo/go/golang_org/x/net/route/interface_classic.go
new file mode 100644
index 00000000000..ac4e7a6805a
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/interface_classic.go
@@ -0,0 +1,66 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly netbsd
+
+package route
+
+import "runtime"
+
+func (w *wireFormat) parseInterfaceMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < w.bodyOff {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	attrs := uint(nativeEndian.Uint32(b[4:8]))
+	if attrs&sysRTA_IFP == 0 {
+		return nil, nil
+	}
+	m := &InterfaceMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Addrs:   make([]Addr, sysRTAX_MAX),
+		Flags:   int(nativeEndian.Uint32(b[8:12])),
+		Index:   int(nativeEndian.Uint16(b[12:14])),
+		extOff:  w.extOff,
+		raw:     b[:l],
+	}
+	a, err := parseLinkAddr(b[w.bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	m.Addrs[sysRTAX_IFP] = a
+	m.Name = a.(*LinkAddr).Name
+	return m, nil
+}
+
+func (w *wireFormat) parseInterfaceAddrMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < w.bodyOff {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &InterfaceAddrMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[8:12])),
+		raw:     b[:l],
+	}
+	if runtime.GOOS == "netbsd" {
+		m.Index = int(nativeEndian.Uint16(b[16:18]))
+	} else {
+		m.Index = int(nativeEndian.Uint16(b[12:14]))
+	}
+	var err error
+	m.Addrs, err = parseAddrs(uint(nativeEndian.Uint32(b[4:8])), parseKernelInetAddr, b[w.bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/interface_freebsd.go b/libgo/go/golang_org/x/net/route/interface_freebsd.go
new file mode 100644
index 00000000000..c83053915da
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/interface_freebsd.go
@@ -0,0 +1,78 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+func (w *wireFormat) parseInterfaceMessage(typ RIBType, b []byte) (Message, error) {
+	var extOff, bodyOff int
+	if typ == sysNET_RT_IFLISTL {
+		if len(b) < 20 {
+			return nil, errMessageTooShort
+		}
+		extOff = int(nativeEndian.Uint16(b[18:20]))
+		bodyOff = int(nativeEndian.Uint16(b[16:18]))
+	} else {
+		if len(b) < w.bodyOff {
+			return nil, errMessageTooShort
+		}
+		extOff = w.extOff
+		bodyOff = w.bodyOff
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	attrs := uint(nativeEndian.Uint32(b[4:8]))
+	if attrs&sysRTA_IFP == 0 {
+		return nil, nil
+	}
+	m := &InterfaceMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[8:12])),
+		Index:   int(nativeEndian.Uint16(b[12:14])),
+		Addrs:   make([]Addr, sysRTAX_MAX),
+		extOff:  extOff,
+		raw:     b[:l],
+	}
+	a, err := parseLinkAddr(b[bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	m.Addrs[sysRTAX_IFP] = a
+	m.Name = a.(*LinkAddr).Name
+	return m, nil
+}
+
+func (w *wireFormat) parseInterfaceAddrMessage(typ RIBType, b []byte) (Message, error) {
+	var bodyOff int
+	if typ == sysNET_RT_IFLISTL {
+		if len(b) < 24 {
+			return nil, errMessageTooShort
+		}
+		bodyOff = int(nativeEndian.Uint16(b[16:18]))
+	} else {
+		if len(b) < w.bodyOff {
+			return nil, errMessageTooShort
+		}
+		bodyOff = w.bodyOff
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &InterfaceAddrMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[8:12])),
+		Index:   int(nativeEndian.Uint16(b[12:14])),
+		raw:     b[:l],
+	}
+	var err error
+	m.Addrs, err = parseAddrs(uint(nativeEndian.Uint32(b[4:8])), parseKernelInetAddr, b[bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/interface_multicast.go b/libgo/go/golang_org/x/net/route/interface_multicast.go
new file mode 100644
index 00000000000..1e99a9cc64b
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/interface_multicast.go
@@ -0,0 +1,30 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd
+
+package route
+
+func (w *wireFormat) parseInterfaceMulticastAddrMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < w.bodyOff {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &InterfaceMulticastAddrMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[8:12])),
+		Index:   int(nativeEndian.Uint16(b[12:14])),
+		raw:     b[:l],
+	}
+	var err error
+	m.Addrs, err = parseAddrs(uint(nativeEndian.Uint32(b[4:8])), parseKernelInetAddr, b[w.bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/interface_openbsd.go b/libgo/go/golang_org/x/net/route/interface_openbsd.go
new file mode 100644
index 00000000000..24451d8ca12
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/interface_openbsd.go
@@ -0,0 +1,83 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+func (*wireFormat) parseInterfaceMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < 32 {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	attrs := uint(nativeEndian.Uint32(b[12:16]))
+	if attrs&sysRTA_IFP == 0 {
+		return nil, nil
+	}
+	m := &InterfaceMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[16:20])),
+		Index:   int(nativeEndian.Uint16(b[6:8])),
+		Addrs:   make([]Addr, sysRTAX_MAX),
+		raw:     b[:l],
+	}
+	a, err := parseLinkAddr(b[int(nativeEndian.Uint16(b[4:6])):])
+	if err != nil {
+		return nil, err
+	}
+	m.Addrs[sysRTAX_IFP] = a
+	m.Name = a.(*LinkAddr).Name
+	return m, nil
+}
+
+func (*wireFormat) parseInterfaceAddrMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < 24 {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	bodyOff := int(nativeEndian.Uint16(b[4:6]))
+	m := &InterfaceAddrMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[12:16])),
+		Index:   int(nativeEndian.Uint16(b[6:8])),
+		raw:     b[:l],
+	}
+	var err error
+	m.Addrs, err = parseAddrs(uint(nativeEndian.Uint32(b[12:16])), parseKernelInetAddr, b[bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+func (*wireFormat) parseInterfaceAnnounceMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < 26 {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &InterfaceAnnounceMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Index:   int(nativeEndian.Uint16(b[6:8])),
+		What:    int(nativeEndian.Uint16(b[8:10])),
+		raw:     b[:l],
+	}
+	for i := 0; i < 16; i++ {
+		if b[10+i] != 0 {
+			continue
+		}
+		m.Name = string(b[10 : 10+i])
+		break
+	}
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/message.go b/libgo/go/golang_org/x/net/route/message.go
new file mode 100644
index 00000000000..27cbf6b77ac
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/message.go
@@ -0,0 +1,70 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+// A Message represents a routing message.
+//
+// Note: This interface will be changed to support Marshal method in
+// future version.
+type Message interface {
+	// Sys returns operating system-specific information.
+	Sys() []Sys
+}
+
+// A Sys reprensents operating system-specific information.
+type Sys interface {
+	// SysType returns a type of operating system-specific
+	// information.
+	SysType() SysType
+}
+
+// A SysType represents a type of operating system-specific
+// information.
+type SysType int
+
+const (
+	SysMetrics SysType = iota
+	SysStats
+)
+
+// ParseRIB parses b as a routing information base and returns a list
+// of routing messages.
+func ParseRIB(typ RIBType, b []byte) ([]Message, error) {
+	if !typ.parseable() {
+		return nil, errUnsupportedMessage
+	}
+	var msgs []Message
+	nmsgs, nskips := 0, 0
+	for len(b) > 4 {
+		nmsgs++
+		l := int(nativeEndian.Uint16(b[:2]))
+		if b[2] != sysRTM_VERSION {
+			b = b[l:]
+			continue
+		}
+		mtyp := int(b[3])
+		if fn, ok := parseFns[mtyp]; !ok {
+			nskips++
+		} else {
+			m, err := fn(typ, b)
+			if err != nil {
+				return nil, err
+			}
+			if m == nil {
+				nskips++
+			} else {
+				msgs = append(msgs, m)
+			}
+		}
+		b = b[l:]
+	}
+	// We failed to parse any of the messages - version mismatch?
+	if nmsgs != len(msgs)+nskips {
+		return nil, errMessageMismatch
+	}
+	return msgs, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/message_darwin_test.go b/libgo/go/golang_org/x/net/route/message_darwin_test.go
new file mode 100644
index 00000000000..3fdd12df553
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/message_darwin_test.go
@@ -0,0 +1,27 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+import "testing"
+
+func TestFetchAndParseRIBOnDarwin(t *testing.T) {
+	for _, af := range []int{sysAF_UNSPEC, sysAF_INET, sysAF_INET6} {
+		for _, typ := range []RIBType{sysNET_RT_FLAGS, sysNET_RT_DUMP2, sysNET_RT_IFLIST2} {
+			ms, err := fetchAndParseRIB(af, typ)
+			if err != nil {
+				t.Error(err)
+				continue
+			}
+			ss, err := msgs(ms).validate()
+			if err != nil {
+				t.Errorf("%v %d %v", addrFamily(af), typ, err)
+				continue
+			}
+			for _, s := range ss {
+				t.Log(s)
+			}
+		}
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/message_freebsd_test.go b/libgo/go/golang_org/x/net/route/message_freebsd_test.go
new file mode 100644
index 00000000000..785c273f656
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/message_freebsd_test.go
@@ -0,0 +1,106 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+import (
+	"testing"
+	"time"
+	"unsafe"
+)
+
+func TestFetchAndParseRIBOnFreeBSD(t *testing.T) {
+	for _, af := range []int{sysAF_UNSPEC, sysAF_INET, sysAF_INET6} {
+		for _, typ := range []RIBType{sysNET_RT_IFMALIST} {
+			ms, err := fetchAndParseRIB(af, typ)
+			if err != nil {
+				t.Error(err)
+				continue
+			}
+			ss, err := msgs(ms).validate()
+			if err != nil {
+				t.Errorf("%v %d %v", addrFamily(af), typ, err)
+				continue
+			}
+			for _, s := range ss {
+				t.Log(s)
+			}
+		}
+	}
+}
+
+func TestFetchAndParseRIBOnFreeBSD10AndAbove(t *testing.T) {
+	if _, err := FetchRIB(sysAF_UNSPEC, sysNET_RT_IFLISTL, 0); err != nil {
+		t.Skip("NET_RT_IFLISTL not supported")
+	}
+	var p uintptr
+	if kernelAlign != int(unsafe.Sizeof(p)) {
+		t.Skip("NET_RT_IFLIST vs. NET_RT_IFLISTL doesn't work for 386 emulation on amd64")
+	}
+
+	var tests = [2]struct {
+		typ  RIBType
+		b    []byte
+		msgs []Message
+		ss   []string
+	}{
+		{typ: sysNET_RT_IFLIST},
+		{typ: sysNET_RT_IFLISTL},
+	}
+	for _, af := range []int{sysAF_UNSPEC, sysAF_INET, sysAF_INET6} {
+		var lastErr error
+		for i := 0; i < 3; i++ {
+			for j := range tests {
+				var err error
+				if tests[j].b, err = FetchRIB(af, tests[j].typ, 0); err != nil {
+					lastErr = err
+					time.Sleep(10 * time.Millisecond)
+				}
+			}
+			if lastErr == nil {
+				break
+			}
+		}
+		if lastErr != nil {
+			t.Error(af, lastErr)
+			continue
+		}
+		for i := range tests {
+			var err error
+			if tests[i].msgs, err = ParseRIB(tests[i].typ, tests[i].b); err != nil {
+				lastErr = err
+				t.Error(af, err)
+			}
+		}
+		if lastErr != nil {
+			continue
+		}
+		for i := range tests {
+			var err error
+			tests[i].ss, err = msgs(tests[i].msgs).validate()
+			if err != nil {
+				lastErr = err
+				t.Error(af, err)
+			}
+			for _, s := range tests[i].ss {
+				t.Log(s)
+			}
+		}
+		if lastErr != nil {
+			continue
+		}
+		for i := len(tests) - 1; i > 0; i-- {
+			if len(tests[i].ss) != len(tests[i-1].ss) {
+				t.Errorf("got %v; want %v", tests[i].ss, tests[i-1].ss)
+				continue
+			}
+			for j, s1 := range tests[i].ss {
+				s0 := tests[i-1].ss[j]
+				if s1 != s0 {
+					t.Errorf("got %s; want %s", s1, s0)
+				}
+			}
+		}
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/message_test.go b/libgo/go/golang_org/x/net/route/message_test.go
new file mode 100644
index 00000000000..a1263d8f25e
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/message_test.go
@@ -0,0 +1,95 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+import (
+	"os"
+	"syscall"
+	"testing"
+	"time"
+)
+
+func TestFetchAndParseRIB(t *testing.T) {
+	for _, af := range []int{sysAF_UNSPEC, sysAF_INET, sysAF_INET6} {
+		for _, typ := range []RIBType{sysNET_RT_DUMP, sysNET_RT_IFLIST} {
+			ms, err := fetchAndParseRIB(af, typ)
+			if err != nil {
+				t.Error(err)
+				continue
+			}
+			ss, err := msgs(ms).validate()
+			if err != nil {
+				t.Errorf("%v %d %v", addrFamily(af), typ, err)
+				continue
+			}
+			for _, s := range ss {
+				t.Log(s)
+			}
+		}
+	}
+}
+
+func TestMonitorAndParseRIB(t *testing.T) {
+	if testing.Short() || os.Getuid() != 0 {
+		t.Skip("must be root")
+	}
+
+	// We suppose that using an IPv4 link-local address and the
+	// dot1Q ID for Token Ring and FDDI doesn't harm anyone.
+	pv := &propVirtual{addr: "169.254.0.1", mask: "255.255.255.0"}
+	if err := pv.configure(1002); err != nil {
+		t.Skip(err)
+	}
+	if err := pv.setup(); err != nil {
+		t.Skip(err)
+	}
+	pv.teardown()
+
+	s, err := syscall.Socket(syscall.AF_ROUTE, syscall.SOCK_RAW, syscall.AF_UNSPEC)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer syscall.Close(s)
+
+	go func() {
+		b := make([]byte, os.Getpagesize())
+		for {
+			n, err := syscall.Read(s, b)
+			if err != nil {
+				return
+			}
+			ms, err := ParseRIB(0, b[:n])
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			ss, err := msgs(ms).validate()
+			if err != nil {
+				t.Error(err)
+				return
+			}
+			for _, s := range ss {
+				t.Log(s)
+			}
+		}
+	}()
+
+	for _, vid := range []int{1002, 1003, 1004, 1005} {
+		pv := &propVirtual{addr: "169.254.0.1", mask: "255.255.255.0"}
+		if err := pv.configure(vid); err != nil {
+			t.Fatal(err)
+		}
+		if err := pv.setup(); err != nil {
+			t.Fatal(err)
+		}
+		time.Sleep(200 * time.Millisecond)
+		if err := pv.teardown(); err != nil {
+			t.Fatal(err)
+		}
+		time.Sleep(200 * time.Millisecond)
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/route.go b/libgo/go/golang_org/x/net/route/route.go
new file mode 100644
index 00000000000..c986e29ebc9
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/route.go
@@ -0,0 +1,74 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+// Package route provides basic functions for the manipulation of
+// packet routing facilities on BSD variants.
+//
+// The package supports any version of Darwin, any version of
+// DragonFly BSD, FreeBSD 7 through 11, NetBSD 6 and above, and
+// OpenBSD 5.6 and above.
+package route
+
+import (
+	"errors"
+	"os"
+	"syscall"
+)
+
+var (
+	errUnsupportedMessage = errors.New("unsupported message")
+	errMessageMismatch    = errors.New("message mismatch")
+	errMessageTooShort    = errors.New("message too short")
+	errInvalidMessage     = errors.New("invalid message")
+	errInvalidAddr        = errors.New("invalid address")
+)
+
+// A RouteMessage represents a message conveying an address prefix, a
+// nexthop address and an output interface.
+type RouteMessage struct {
+	Version int    // message version
+	Type    int    // message type
+	Flags   int    // route flags
+	Index   int    // interface index when atatched
+	Addrs   []Addr // addresses
+
+	extOff int    // offset of header extension
+	raw    []byte // raw message
+}
+
+// A RIBType reprensents a type of routing information base.
+type RIBType int
+
+const (
+	RIBTypeRoute     RIBType = syscall.NET_RT_DUMP
+	RIBTypeInterface RIBType = syscall.NET_RT_IFLIST
+)
+
+// FetchRIB fetches a routing information base from the operating
+// system.
+//
+// The provided af must be an address family.
+//
+// The provided arg must be a RIBType-specific argument.
+// When RIBType is related to routes, arg might be a set of route
+// flags. When RIBType is related to network interfaces, arg might be
+// an interface index or a set of interface flags. In most cases, zero
+// means a wildcard.
+func FetchRIB(af int, typ RIBType, arg int) ([]byte, error) {
+	mib := [6]int32{sysCTL_NET, sysAF_ROUTE, 0, int32(af), int32(typ), int32(arg)}
+	n := uintptr(0)
+	if err := sysctl(mib[:], nil, &n, nil, 0); err != nil {
+		return nil, os.NewSyscallError("sysctl", err)
+	}
+	if n == 0 {
+		return nil, nil
+	}
+	b := make([]byte, n)
+	if err := sysctl(mib[:], &b[0], &n, nil, 0); err != nil {
+		return nil, os.NewSyscallError("sysctl", err)
+	}
+	return b[:n], nil
+}
diff --git a/libgo/go/golang_org/x/net/route/route_classic.go b/libgo/go/golang_org/x/net/route/route_classic.go
new file mode 100644
index 00000000000..d333c6aa526
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/route_classic.go
@@ -0,0 +1,31 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd
+
+package route
+
+func (w *wireFormat) parseRouteMessage(typ RIBType, b []byte) (Message, error) {
+	if len(b) < w.bodyOff {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &RouteMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[8:12])),
+		Index:   int(nativeEndian.Uint16(b[4:6])),
+		extOff:  w.extOff,
+		raw:     b[:l],
+	}
+	var err error
+	m.Addrs, err = parseAddrs(uint(nativeEndian.Uint32(b[12:16])), parseKernelInetAddr, b[w.bodyOff:])
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/route_openbsd.go b/libgo/go/golang_org/x/net/route/route_openbsd.go
new file mode 100644
index 00000000000..b07862f04d3
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/route_openbsd.go
@@ -0,0 +1,28 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+func (*wireFormat) parseRouteMessage(_ RIBType, b []byte) (Message, error) {
+	if len(b) < 40 {
+		return nil, errMessageTooShort
+	}
+	l := int(nativeEndian.Uint16(b[:2]))
+	if len(b) < l {
+		return nil, errInvalidMessage
+	}
+	m := &RouteMessage{
+		Version: int(b[2]),
+		Type:    int(b[3]),
+		Flags:   int(nativeEndian.Uint32(b[16:20])),
+		Index:   int(nativeEndian.Uint16(b[6:8])),
+		raw:     b[:l],
+	}
+	as, err := parseAddrs(uint(nativeEndian.Uint32(b[12:16])), parseKernelInetAddr, b[int(nativeEndian.Uint16(b[4:6])):])
+	if err != nil {
+		return nil, err
+	}
+	m.Addrs = as
+	return m, nil
+}
diff --git a/libgo/go/golang_org/x/net/route/route_test.go b/libgo/go/golang_org/x/net/route/route_test.go
new file mode 100644
index 00000000000..99f57b712d9
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/route_test.go
@@ -0,0 +1,385 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+	"time"
+)
+
+func (m *RouteMessage) String() string {
+	return fmt.Sprintf("%s", addrAttrs(nativeEndian.Uint32(m.raw[12:16])))
+}
+
+func (m *InterfaceMessage) String() string {
+	var attrs addrAttrs
+	if runtime.GOOS == "openbsd" {
+		attrs = addrAttrs(nativeEndian.Uint32(m.raw[12:16]))
+	} else {
+		attrs = addrAttrs(nativeEndian.Uint32(m.raw[4:8]))
+	}
+	return fmt.Sprintf("%s", attrs)
+}
+
+func (m *InterfaceAddrMessage) String() string {
+	var attrs addrAttrs
+	if runtime.GOOS == "openbsd" {
+		attrs = addrAttrs(nativeEndian.Uint32(m.raw[12:16]))
+	} else {
+		attrs = addrAttrs(nativeEndian.Uint32(m.raw[4:8]))
+	}
+	return fmt.Sprintf("%s", attrs)
+}
+
+func (m *InterfaceMulticastAddrMessage) String() string {
+	return fmt.Sprintf("%s", addrAttrs(nativeEndian.Uint32(m.raw[4:8])))
+}
+
+func (m *InterfaceAnnounceMessage) String() string {
+	what := "<nil>"
+	switch m.What {
+	case 0:
+		what = "arrival"
+	case 1:
+		what = "departure"
+	}
+	return fmt.Sprintf("(%d %s %s)", m.Index, m.Name, what)
+}
+
+func (m *InterfaceMetrics) String() string {
+	return fmt.Sprintf("(type=%d mtu=%d)", m.Type, m.MTU)
+}
+
+func (m *RouteMetrics) String() string {
+	return fmt.Sprintf("(pmtu=%d)", m.PathMTU)
+}
+
+type addrAttrs uint
+
+var addrAttrNames = [...]string{
+	"dst",
+	"gateway",
+	"netmask",
+	"genmask",
+	"ifp",
+	"ifa",
+	"author",
+	"brd",
+	"df:mpls1-n:tag-o:src", // mpls1 for dragonfly, tag for netbsd, src for openbsd
+	"df:mpls2-o:srcmask",   // mpls2 for dragonfly, srcmask for openbsd
+	"df:mpls3-o:label",     // mpls3 for dragonfly, label for openbsd
+}
+
+func (attrs addrAttrs) String() string {
+	var s string
+	for i, name := range addrAttrNames {
+		if attrs&(1<<uint(i)) != 0 {
+			if s != "" {
+				s += "|"
+			}
+			s += name
+		}
+	}
+	if s == "" {
+		return "<nil>"
+	}
+	return s
+}
+
+type msgs []Message
+
+func (ms msgs) validate() ([]string, error) {
+	var ss []string
+	for _, m := range ms {
+		switch m := m.(type) {
+		case *RouteMessage:
+			if err := addrs(m.Addrs).match(addrAttrs(nativeEndian.Uint32(m.raw[12:16]))); err != nil {
+				return nil, err
+			}
+			sys := m.Sys()
+			if sys == nil {
+				return nil, fmt.Errorf("no sys for %s", m.String())
+			}
+			ss = append(ss, m.String()+" "+syss(sys).String()+" "+addrs(m.Addrs).String())
+		case *InterfaceMessage:
+			var attrs addrAttrs
+			if runtime.GOOS == "openbsd" {
+				attrs = addrAttrs(nativeEndian.Uint32(m.raw[12:16]))
+			} else {
+				attrs = addrAttrs(nativeEndian.Uint32(m.raw[4:8]))
+			}
+			if err := addrs(m.Addrs).match(attrs); err != nil {
+				return nil, err
+			}
+			sys := m.Sys()
+			if sys == nil {
+				return nil, fmt.Errorf("no sys for %s", m.String())
+			}
+			ss = append(ss, m.String()+" "+syss(sys).String()+" "+addrs(m.Addrs).String())
+		case *InterfaceAddrMessage:
+			var attrs addrAttrs
+			if runtime.GOOS == "openbsd" {
+				attrs = addrAttrs(nativeEndian.Uint32(m.raw[12:16]))
+			} else {
+				attrs = addrAttrs(nativeEndian.Uint32(m.raw[4:8]))
+			}
+			if err := addrs(m.Addrs).match(attrs); err != nil {
+				return nil, err
+			}
+			ss = append(ss, m.String()+" "+addrs(m.Addrs).String())
+		case *InterfaceMulticastAddrMessage:
+			if err := addrs(m.Addrs).match(addrAttrs(nativeEndian.Uint32(m.raw[4:8]))); err != nil {
+				return nil, err
+			}
+			ss = append(ss, m.String()+" "+addrs(m.Addrs).String())
+		case *InterfaceAnnounceMessage:
+			ss = append(ss, m.String())
+		default:
+			ss = append(ss, fmt.Sprintf("%+v", m))
+		}
+	}
+	return ss, nil
+}
+
+type syss []Sys
+
+func (sys syss) String() string {
+	var s string
+	for _, sy := range sys {
+		switch sy := sy.(type) {
+		case *InterfaceMetrics:
+			if len(s) > 0 {
+				s += " "
+			}
+			s += sy.String()
+		case *RouteMetrics:
+			if len(s) > 0 {
+				s += " "
+			}
+			s += sy.String()
+		}
+	}
+	return s
+}
+
+type addrFamily int
+
+func (af addrFamily) String() string {
+	switch af {
+	case sysAF_UNSPEC:
+		return "unspec"
+	case sysAF_LINK:
+		return "link"
+	case sysAF_INET:
+		return "inet4"
+	case sysAF_INET6:
+		return "inet6"
+	default:
+		return fmt.Sprintf("%d", af)
+	}
+}
+
+const hexDigit = "0123456789abcdef"
+
+type llAddr []byte
+
+func (a llAddr) String() string {
+	if len(a) == 0 {
+		return ""
+	}
+	buf := make([]byte, 0, len(a)*3-1)
+	for i, b := range a {
+		if i > 0 {
+			buf = append(buf, ':')
+		}
+		buf = append(buf, hexDigit[b>>4])
+		buf = append(buf, hexDigit[b&0xF])
+	}
+	return string(buf)
+}
+
+type ipAddr []byte
+
+func (a ipAddr) String() string {
+	if len(a) == 0 {
+		return "<nil>"
+	}
+	if len(a) == 4 {
+		return fmt.Sprintf("%d.%d.%d.%d", a[0], a[1], a[2], a[3])
+	}
+	if len(a) == 16 {
+		return fmt.Sprintf("%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x", a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15])
+	}
+	s := make([]byte, len(a)*2)
+	for i, tn := range a {
+		s[i*2], s[i*2+1] = hexDigit[tn>>4], hexDigit[tn&0xf]
+	}
+	return string(s)
+}
+
+func (a *LinkAddr) String() string {
+	name := a.Name
+	if name == "" {
+		name = "<nil>"
+	}
+	lla := llAddr(a.Addr).String()
+	if lla == "" {
+		lla = "<nil>"
+	}
+	return fmt.Sprintf("(%v %d %s %s)", addrFamily(a.Family()), a.Index, name, lla)
+}
+
+func (a Inet4Addr) String() string {
+	return fmt.Sprintf("(%v %v)", addrFamily(a.Family()), ipAddr(a.IP[:]))
+}
+
+func (a *Inet6Addr) String() string {
+	return fmt.Sprintf("(%v %v %d)", addrFamily(a.Family()), ipAddr(a.IP[:]), a.ZoneID)
+}
+
+func (a *DefaultAddr) String() string {
+	return fmt.Sprintf("(%v %s)", addrFamily(a.Family()), ipAddr(a.Raw[2:]).String())
+}
+
+type addrs []Addr
+
+func (as addrs) String() string {
+	var s string
+	for _, a := range as {
+		if a == nil {
+			continue
+		}
+		if len(s) > 0 {
+			s += " "
+		}
+		switch a := a.(type) {
+		case *LinkAddr:
+			s += a.String()
+		case *Inet4Addr:
+			s += a.String()
+		case *Inet6Addr:
+			s += a.String()
+		case *DefaultAddr:
+			s += a.String()
+		}
+	}
+	if s == "" {
+		return "<nil>"
+	}
+	return s
+}
+
+func (as addrs) match(attrs addrAttrs) error {
+	var ts addrAttrs
+	af := sysAF_UNSPEC
+	for i := range as {
+		if as[i] != nil {
+			ts |= 1 << uint(i)
+		}
+		switch as[i].(type) {
+		case *Inet4Addr:
+			if af == sysAF_UNSPEC {
+				af = sysAF_INET
+			}
+			if af != sysAF_INET {
+				return fmt.Errorf("got %v; want %v", addrs(as), addrFamily(af))
+			}
+		case *Inet6Addr:
+			if af == sysAF_UNSPEC {
+				af = sysAF_INET6
+			}
+			if af != sysAF_INET6 {
+				return fmt.Errorf("got %v; want %v", addrs(as), addrFamily(af))
+			}
+		}
+	}
+	if ts != attrs && ts > attrs {
+		return fmt.Errorf("%v not included in %v", ts, attrs)
+	}
+	return nil
+}
+
+func fetchAndParseRIB(af int, typ RIBType) ([]Message, error) {
+	var err error
+	var b []byte
+	for i := 0; i < 3; i++ {
+		if b, err = FetchRIB(af, typ, 0); err != nil {
+			time.Sleep(10 * time.Millisecond)
+			continue
+		}
+		break
+	}
+	if err != nil {
+		return nil, fmt.Errorf("%v %d %v", addrFamily(af), typ, err)
+	}
+	ms, err := ParseRIB(typ, b)
+	if err != nil {
+		return nil, fmt.Errorf("%v %d %v", addrFamily(af), typ, err)
+	}
+	return ms, nil
+}
+
+type propVirtual struct {
+	name         string
+	addr, mask   string
+	setupCmds    []*exec.Cmd
+	teardownCmds []*exec.Cmd
+}
+
+func (ti *propVirtual) setup() error {
+	for _, cmd := range ti.setupCmds {
+		if err := cmd.Run(); err != nil {
+			ti.teardown()
+			return err
+		}
+	}
+	return nil
+}
+
+func (ti *propVirtual) teardown() error {
+	for _, cmd := range ti.teardownCmds {
+		if err := cmd.Run(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (ti *propVirtual) configure(suffix int) error {
+	if runtime.GOOS == "openbsd" {
+		ti.name = fmt.Sprintf("vether%d", suffix)
+	} else {
+		ti.name = fmt.Sprintf("vlan%d", suffix)
+	}
+	xname, err := exec.LookPath("ifconfig")
+	if err != nil {
+		return err
+	}
+	ti.setupCmds = append(ti.setupCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ifconfig", ti.name, "create"},
+	})
+	if runtime.GOOS == "netbsd" {
+		// NetBSD requires an underlying dot1Q-capable network
+		// interface.
+		ti.setupCmds = append(ti.setupCmds, &exec.Cmd{
+			Path: xname,
+			Args: []string{"ifconfig", ti.name, "vlan", fmt.Sprintf("%d", suffix&0xfff), "vlanif", "wm0"},
+		})
+	}
+	ti.setupCmds = append(ti.setupCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ifconfig", ti.name, "inet", ti.addr, "netmask", ti.mask},
+	})
+	ti.teardownCmds = append(ti.teardownCmds, &exec.Cmd{
+		Path: xname,
+		Args: []string{"ifconfig", ti.name, "destroy"},
+	})
+	return nil
+}
diff --git a/libgo/go/golang_org/x/net/route/sys.go b/libgo/go/golang_org/x/net/route/sys.go
new file mode 100644
index 00000000000..80ca83ae137
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/sys.go
@@ -0,0 +1,40 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+import "unsafe"
+
+var (
+	nativeEndian binaryByteOrder
+	kernelAlign  int
+	parseFns     map[int]parseFn
+)
+
+func init() {
+	i := uint32(1)
+	b := (*[4]byte)(unsafe.Pointer(&i))
+	if b[0] == 1 {
+		nativeEndian = littleEndian
+	} else {
+		nativeEndian = bigEndian
+	}
+	kernelAlign, parseFns = probeRoutingStack()
+}
+
+func roundup(l int) int {
+	if l == 0 {
+		return kernelAlign
+	}
+	return (l + kernelAlign - 1) & ^(kernelAlign - 1)
+}
+
+type parseFn func(RIBType, []byte) (Message, error)
+
+type wireFormat struct {
+	extOff  int // offset of header extension
+	bodyOff int // offset of message body
+}
diff --git a/libgo/go/golang_org/x/net/route/sys_darwin.go b/libgo/go/golang_org/x/net/route/sys_darwin.go
new file mode 100644
index 00000000000..fff3a0fd1db
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/sys_darwin.go
@@ -0,0 +1,80 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+func (typ RIBType) parseable() bool {
+	switch typ {
+	case sysNET_RT_STAT, sysNET_RT_TRASH:
+		return false
+	default:
+		return true
+	}
+}
+
+// A RouteMetrics represents route metrics.
+type RouteMetrics struct {
+	PathMTU int // path maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (rmx *RouteMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *RouteMessage) Sys() []Sys {
+	return []Sys{
+		&RouteMetrics{
+			PathMTU: int(nativeEndian.Uint32(m.raw[m.extOff+4 : m.extOff+8])),
+		},
+	}
+}
+
+// A InterfaceMetrics represents interface metrics.
+type InterfaceMetrics struct {
+	Type int // interface type
+	MTU  int // maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (imx *InterfaceMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceMessage) Sys() []Sys {
+	return []Sys{
+		&InterfaceMetrics{
+			Type: int(m.raw[m.extOff]),
+			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
+		},
+	}
+}
+
+func probeRoutingStack() (int, map[int]parseFn) {
+	rtm := &wireFormat{extOff: 36, bodyOff: sizeofRtMsghdrDarwin15}
+	rtm2 := &wireFormat{extOff: 36, bodyOff: sizeofRtMsghdr2Darwin15}
+	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrDarwin15}
+	ifm2 := &wireFormat{extOff: 32, bodyOff: sizeofIfMsghdr2Darwin15}
+	ifam := &wireFormat{extOff: sizeofIfaMsghdrDarwin15, bodyOff: sizeofIfaMsghdrDarwin15}
+	ifmam := &wireFormat{extOff: sizeofIfmaMsghdrDarwin15, bodyOff: sizeofIfmaMsghdrDarwin15}
+	ifmam2 := &wireFormat{extOff: sizeofIfmaMsghdr2Darwin15, bodyOff: sizeofIfmaMsghdr2Darwin15}
+	// Darwin kernels require 32-bit aligned access to routing facilities.
+	return 4, map[int]parseFn{
+		sysRTM_ADD:       rtm.parseRouteMessage,
+		sysRTM_DELETE:    rtm.parseRouteMessage,
+		sysRTM_CHANGE:    rtm.parseRouteMessage,
+		sysRTM_GET:       rtm.parseRouteMessage,
+		sysRTM_LOSING:    rtm.parseRouteMessage,
+		sysRTM_REDIRECT:  rtm.parseRouteMessage,
+		sysRTM_MISS:      rtm.parseRouteMessage,
+		sysRTM_LOCK:      rtm.parseRouteMessage,
+		sysRTM_RESOLVE:   rtm.parseRouteMessage,
+		sysRTM_NEWADDR:   ifam.parseInterfaceAddrMessage,
+		sysRTM_DELADDR:   ifam.parseInterfaceAddrMessage,
+		sysRTM_IFINFO:    ifm.parseInterfaceMessage,
+		sysRTM_NEWMADDR:  ifmam.parseInterfaceMulticastAddrMessage,
+		sysRTM_DELMADDR:  ifmam.parseInterfaceMulticastAddrMessage,
+		sysRTM_IFINFO2:   ifm2.parseInterfaceMessage,
+		sysRTM_NEWMADDR2: ifmam2.parseInterfaceMulticastAddrMessage,
+		sysRTM_GET2:      rtm2.parseRouteMessage,
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/sys_dragonfly.go b/libgo/go/golang_org/x/net/route/sys_dragonfly.go
new file mode 100644
index 00000000000..da848b3d076
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/sys_dragonfly.go
@@ -0,0 +1,71 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+import "unsafe"
+
+func (typ RIBType) parseable() bool { return true }
+
+// A RouteMetrics represents route metrics.
+type RouteMetrics struct {
+	PathMTU int // path maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (rmx *RouteMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *RouteMessage) Sys() []Sys {
+	return []Sys{
+		&RouteMetrics{
+			PathMTU: int(nativeEndian.Uint64(m.raw[m.extOff+8 : m.extOff+16])),
+		},
+	}
+}
+
+// A InterfaceMetrics represents interface metrics.
+type InterfaceMetrics struct {
+	Type int // interface type
+	MTU  int // maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (imx *InterfaceMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceMessage) Sys() []Sys {
+	return []Sys{
+		&InterfaceMetrics{
+			Type: int(m.raw[m.extOff]),
+			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
+		},
+	}
+}
+
+func probeRoutingStack() (int, map[int]parseFn) {
+	var p uintptr
+	rtm := &wireFormat{extOff: 40, bodyOff: sizeofRtMsghdrDragonFlyBSD4}
+	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrDragonFlyBSD4}
+	ifam := &wireFormat{extOff: sizeofIfaMsghdrDragonFlyBSD4, bodyOff: sizeofIfaMsghdrDragonFlyBSD4}
+	ifmam := &wireFormat{extOff: sizeofIfmaMsghdrDragonFlyBSD4, bodyOff: sizeofIfmaMsghdrDragonFlyBSD4}
+	ifanm := &wireFormat{extOff: sizeofIfAnnouncemsghdrDragonFlyBSD4, bodyOff: sizeofIfAnnouncemsghdrDragonFlyBSD4}
+	return int(unsafe.Sizeof(p)), map[int]parseFn{
+		sysRTM_ADD:        rtm.parseRouteMessage,
+		sysRTM_DELETE:     rtm.parseRouteMessage,
+		sysRTM_CHANGE:     rtm.parseRouteMessage,
+		sysRTM_GET:        rtm.parseRouteMessage,
+		sysRTM_LOSING:     rtm.parseRouteMessage,
+		sysRTM_REDIRECT:   rtm.parseRouteMessage,
+		sysRTM_MISS:       rtm.parseRouteMessage,
+		sysRTM_LOCK:       rtm.parseRouteMessage,
+		sysRTM_RESOLVE:    rtm.parseRouteMessage,
+		sysRTM_NEWADDR:    ifam.parseInterfaceAddrMessage,
+		sysRTM_DELADDR:    ifam.parseInterfaceAddrMessage,
+		sysRTM_IFINFO:     ifm.parseInterfaceMessage,
+		sysRTM_NEWMADDR:   ifmam.parseInterfaceMulticastAddrMessage,
+		sysRTM_DELMADDR:   ifmam.parseInterfaceMulticastAddrMessage,
+		sysRTM_IFANNOUNCE: ifanm.parseInterfaceAnnounceMessage,
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/sys_freebsd.go b/libgo/go/golang_org/x/net/route/sys_freebsd.go
new file mode 100644
index 00000000000..7b05c1a5a05
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/sys_freebsd.go
@@ -0,0 +1,150 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func (typ RIBType) parseable() bool { return true }
+
+// A RouteMetrics represents route metrics.
+type RouteMetrics struct {
+	PathMTU int // path maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (rmx *RouteMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *RouteMessage) Sys() []Sys {
+	if kernelAlign == 8 {
+		return []Sys{
+			&RouteMetrics{
+				PathMTU: int(nativeEndian.Uint64(m.raw[m.extOff+8 : m.extOff+16])),
+			},
+		}
+	}
+	return []Sys{
+		&RouteMetrics{
+			PathMTU: int(nativeEndian.Uint32(m.raw[m.extOff+4 : m.extOff+8])),
+		},
+	}
+}
+
+// A InterfaceMetrics represents interface metrics.
+type InterfaceMetrics struct {
+	Type int // interface type
+	MTU  int // maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (imx *InterfaceMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceMessage) Sys() []Sys {
+	return []Sys{
+		&InterfaceMetrics{
+			Type: int(m.raw[m.extOff]),
+			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
+		},
+	}
+}
+
+func probeRoutingStack() (int, map[int]parseFn) {
+	var p uintptr
+	wordSize := int(unsafe.Sizeof(p))
+	align := int(unsafe.Sizeof(p))
+	// In the case of kern.supported_archs="amd64 i386", we need
+	// to know the underlying kernel's architecture because the
+	// alignment for routing facilities are set at the build time
+	// of the kernel.
+	conf, _ := syscall.Sysctl("kern.conftxt")
+	for i, j := 0, 0; j < len(conf); j++ {
+		if conf[j] != '\n' {
+			continue
+		}
+		s := conf[i:j]
+		i = j + 1
+		if len(s) > len("machine") && s[:len("machine")] == "machine" {
+			s = s[len("machine"):]
+			for k := 0; k < len(s); k++ {
+				if s[k] == ' ' || s[k] == '\t' {
+					s = s[1:]
+				}
+				break
+			}
+			if s == "amd64" {
+				align = 8
+			}
+			break
+		}
+	}
+	var rtm, ifm, ifam, ifmam, ifanm *wireFormat
+	if align != wordSize { // 386 emulation on amd64
+		rtm = &wireFormat{extOff: sizeofRtMsghdrFreeBSD10Emu - sizeofRtMetricsFreeBSD10Emu, bodyOff: sizeofRtMsghdrFreeBSD10Emu}
+		ifm = &wireFormat{extOff: 16}
+		ifam = &wireFormat{extOff: sizeofIfaMsghdrFreeBSD10Emu, bodyOff: sizeofIfaMsghdrFreeBSD10Emu}
+		ifmam = &wireFormat{extOff: sizeofIfmaMsghdrFreeBSD10Emu, bodyOff: sizeofIfmaMsghdrFreeBSD10Emu}
+		ifanm = &wireFormat{extOff: sizeofIfAnnouncemsghdrFreeBSD10Emu, bodyOff: sizeofIfAnnouncemsghdrFreeBSD10Emu}
+	} else {
+		rtm = &wireFormat{extOff: sizeofRtMsghdrFreeBSD10 - sizeofRtMetricsFreeBSD10, bodyOff: sizeofRtMsghdrFreeBSD10}
+		ifm = &wireFormat{extOff: 16}
+		ifam = &wireFormat{extOff: sizeofIfaMsghdrFreeBSD10, bodyOff: sizeofIfaMsghdrFreeBSD10}
+		ifmam = &wireFormat{extOff: sizeofIfmaMsghdrFreeBSD10, bodyOff: sizeofIfmaMsghdrFreeBSD10}
+		ifanm = &wireFormat{extOff: sizeofIfAnnouncemsghdrFreeBSD10, bodyOff: sizeofIfAnnouncemsghdrFreeBSD10}
+	}
+	rel, _ := syscall.SysctlUint32("kern.osreldate")
+	switch {
+	case rel < 800000:
+		if align != wordSize { // 386 emulation on amd64
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD7Emu
+		} else {
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD7
+		}
+	case 800000 <= rel && rel < 900000:
+		if align != wordSize { // 386 emulation on amd64
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD8Emu
+		} else {
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD8
+		}
+	case 900000 <= rel && rel < 1000000:
+		if align != wordSize { // 386 emulation on amd64
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD9Emu
+		} else {
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD9
+		}
+	case 1000000 <= rel && rel < 1100000:
+		if align != wordSize { // 386 emulation on amd64
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD10Emu
+		} else {
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD10
+		}
+	default:
+		if align != wordSize { // 386 emulation on amd64
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD11Emu
+		} else {
+			ifm.bodyOff = sizeofIfMsghdrFreeBSD11
+		}
+	}
+	return align, map[int]parseFn{
+		sysRTM_ADD:        rtm.parseRouteMessage,
+		sysRTM_DELETE:     rtm.parseRouteMessage,
+		sysRTM_CHANGE:     rtm.parseRouteMessage,
+		sysRTM_GET:        rtm.parseRouteMessage,
+		sysRTM_LOSING:     rtm.parseRouteMessage,
+		sysRTM_REDIRECT:   rtm.parseRouteMessage,
+		sysRTM_MISS:       rtm.parseRouteMessage,
+		sysRTM_LOCK:       rtm.parseRouteMessage,
+		sysRTM_RESOLVE:    rtm.parseRouteMessage,
+		sysRTM_NEWADDR:    ifam.parseInterfaceAddrMessage,
+		sysRTM_DELADDR:    ifam.parseInterfaceAddrMessage,
+		sysRTM_IFINFO:     ifm.parseInterfaceMessage,
+		sysRTM_NEWMADDR:   ifmam.parseInterfaceMulticastAddrMessage,
+		sysRTM_DELMADDR:   ifmam.parseInterfaceMulticastAddrMessage,
+		sysRTM_IFANNOUNCE: ifanm.parseInterfaceAnnounceMessage,
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/sys_netbsd.go b/libgo/go/golang_org/x/net/route/sys_netbsd.go
new file mode 100644
index 00000000000..4d8076b518d
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/sys_netbsd.go
@@ -0,0 +1,67 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+func (typ RIBType) parseable() bool { return true }
+
+// A RouteMetrics represents route metrics.
+type RouteMetrics struct {
+	PathMTU int // path maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (rmx *RouteMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *RouteMessage) Sys() []Sys {
+	return []Sys{
+		&RouteMetrics{
+			PathMTU: int(nativeEndian.Uint64(m.raw[m.extOff+8 : m.extOff+16])),
+		},
+	}
+}
+
+// A InterfaceMetrics represents interface metrics.
+type InterfaceMetrics struct {
+	Type int // interface type
+	MTU  int // maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (imx *InterfaceMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceMessage) Sys() []Sys {
+	return []Sys{
+		&InterfaceMetrics{
+			Type: int(m.raw[m.extOff]),
+			MTU:  int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12])),
+		},
+	}
+}
+
+func probeRoutingStack() (int, map[int]parseFn) {
+	rtm := &wireFormat{extOff: 40, bodyOff: sizeofRtMsghdrNetBSD7}
+	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdrNetBSD7}
+	ifam := &wireFormat{extOff: sizeofIfaMsghdrNetBSD7, bodyOff: sizeofIfaMsghdrNetBSD7}
+	ifanm := &wireFormat{extOff: sizeofIfAnnouncemsghdrNetBSD7, bodyOff: sizeofIfAnnouncemsghdrNetBSD7}
+	// NetBSD 6 and above kernels require 64-bit aligned access to
+	// routing facilities.
+	return 8, map[int]parseFn{
+		sysRTM_ADD:        rtm.parseRouteMessage,
+		sysRTM_DELETE:     rtm.parseRouteMessage,
+		sysRTM_CHANGE:     rtm.parseRouteMessage,
+		sysRTM_GET:        rtm.parseRouteMessage,
+		sysRTM_LOSING:     rtm.parseRouteMessage,
+		sysRTM_REDIRECT:   rtm.parseRouteMessage,
+		sysRTM_MISS:       rtm.parseRouteMessage,
+		sysRTM_LOCK:       rtm.parseRouteMessage,
+		sysRTM_RESOLVE:    rtm.parseRouteMessage,
+		sysRTM_NEWADDR:    ifam.parseInterfaceAddrMessage,
+		sysRTM_DELADDR:    ifam.parseInterfaceAddrMessage,
+		sysRTM_IFANNOUNCE: ifanm.parseInterfaceAnnounceMessage,
+		sysRTM_IFINFO:     ifm.parseInterfaceMessage,
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/sys_openbsd.go b/libgo/go/golang_org/x/net/route/sys_openbsd.go
new file mode 100644
index 00000000000..26d04386961
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/sys_openbsd.go
@@ -0,0 +1,72 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package route
+
+import "unsafe"
+
+func (typ RIBType) parseable() bool {
+	switch typ {
+	case sysNET_RT_STATS, sysNET_RT_TABLE:
+		return false
+	default:
+		return true
+	}
+}
+
+// A RouteMetrics represents route metrics.
+type RouteMetrics struct {
+	PathMTU int // path maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (rmx *RouteMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *RouteMessage) Sys() []Sys {
+	return []Sys{
+		&RouteMetrics{
+			PathMTU: int(nativeEndian.Uint32(m.raw[60:64])),
+		},
+	}
+}
+
+// A InterfaceMetrics represents interface metrics.
+type InterfaceMetrics struct {
+	Type int // interface type
+	MTU  int // maximum transmission unit
+}
+
+// SysType implements the SysType method of Sys interface.
+func (imx *InterfaceMetrics) SysType() SysType { return SysMetrics }
+
+// Sys implements the Sys method of Message interface.
+func (m *InterfaceMessage) Sys() []Sys {
+	return []Sys{
+		&InterfaceMetrics{
+			Type: int(m.raw[24]),
+			MTU:  int(nativeEndian.Uint32(m.raw[28:32])),
+		},
+	}
+}
+
+func probeRoutingStack() (int, map[int]parseFn) {
+	var p uintptr
+	nooff := &wireFormat{extOff: -1, bodyOff: -1}
+	return int(unsafe.Sizeof(p)), map[int]parseFn{
+		sysRTM_ADD:        nooff.parseRouteMessage,
+		sysRTM_DELETE:     nooff.parseRouteMessage,
+		sysRTM_CHANGE:     nooff.parseRouteMessage,
+		sysRTM_GET:        nooff.parseRouteMessage,
+		sysRTM_LOSING:     nooff.parseRouteMessage,
+		sysRTM_REDIRECT:   nooff.parseRouteMessage,
+		sysRTM_MISS:       nooff.parseRouteMessage,
+		sysRTM_LOCK:       nooff.parseRouteMessage,
+		sysRTM_RESOLVE:    nooff.parseRouteMessage,
+		sysRTM_NEWADDR:    nooff.parseInterfaceAddrMessage,
+		sysRTM_DELADDR:    nooff.parseInterfaceAddrMessage,
+		sysRTM_IFINFO:     nooff.parseInterfaceMessage,
+		sysRTM_IFANNOUNCE: nooff.parseInterfaceAnnounceMessage,
+	}
+}
diff --git a/libgo/go/golang_org/x/net/route/syscall.go b/libgo/go/golang_org/x/net/route/syscall.go
new file mode 100644
index 00000000000..d136325a30a
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/syscall.go
@@ -0,0 +1,33 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package route
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// TODO: replace with runtime.KeepAlive when available
+//go:noescape
+func keepAlive(p unsafe.Pointer)
+
+var zero uintptr
+
+func sysctl(mib []int32, old *byte, oldlen *uintptr, new *byte, newlen uintptr) error {
+	var p unsafe.Pointer
+	if len(mib) > 0 {
+		p = unsafe.Pointer(&mib[0])
+	} else {
+		p = unsafe.Pointer(&zero)
+	}
+	_, _, errno := syscall.Syscall6(syscall.SYS___SYSCTL, uintptr(p), uintptr(len(mib)), uintptr(unsafe.Pointer(old)), uintptr(unsafe.Pointer(oldlen)), uintptr(unsafe.Pointer(new)), uintptr(newlen))
+	keepAlive(p)
+	if errno != 0 {
+		return error(errno)
+	}
+	return nil
+}
diff --git a/libgo/go/golang_org/x/net/route/zsys_darwin.go b/libgo/go/golang_org/x/net/route/zsys_darwin.go
new file mode 100644
index 00000000000..265b81cd50e
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_darwin.go
@@ -0,0 +1,93 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_darwin.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x11
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x1e
+
+	sysNET_RT_DUMP    = 0x1
+	sysNET_RT_FLAGS   = 0x2
+	sysNET_RT_IFLIST  = 0x3
+	sysNET_RT_STAT    = 0x4
+	sysNET_RT_TRASH   = 0x5
+	sysNET_RT_IFLIST2 = 0x6
+	sysNET_RT_DUMP2   = 0x7
+	sysNET_RT_MAXID   = 0xa
+)
+
+const (
+	sysCTL_MAXNAME = 0xc
+
+	sysCTL_UNSPEC  = 0x0
+	sysCTL_KERN    = 0x1
+	sysCTL_VM      = 0x2
+	sysCTL_VFS     = 0x3
+	sysCTL_NET     = 0x4
+	sysCTL_DEBUG   = 0x5
+	sysCTL_HW      = 0x6
+	sysCTL_MACHDEP = 0x7
+	sysCTL_USER    = 0x8
+	sysCTL_MAXID   = 0x9
+)
+
+const (
+	sysRTM_VERSION = 0x5
+
+	sysRTM_ADD       = 0x1
+	sysRTM_DELETE    = 0x2
+	sysRTM_CHANGE    = 0x3
+	sysRTM_GET       = 0x4
+	sysRTM_LOSING    = 0x5
+	sysRTM_REDIRECT  = 0x6
+	sysRTM_MISS      = 0x7
+	sysRTM_LOCK      = 0x8
+	sysRTM_OLDADD    = 0x9
+	sysRTM_OLDDEL    = 0xa
+	sysRTM_RESOLVE   = 0xb
+	sysRTM_NEWADDR   = 0xc
+	sysRTM_DELADDR   = 0xd
+	sysRTM_IFINFO    = 0xe
+	sysRTM_NEWMADDR  = 0xf
+	sysRTM_DELMADDR  = 0x10
+	sysRTM_IFINFO2   = 0x12
+	sysRTM_NEWMADDR2 = 0x13
+	sysRTM_GET2      = 0x14
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_MAX     = 0x8
+)
+
+const (
+	sizeofIfMsghdrDarwin15    = 0x70
+	sizeofIfaMsghdrDarwin15   = 0x14
+	sizeofIfmaMsghdrDarwin15  = 0x10
+	sizeofIfMsghdr2Darwin15   = 0xa0
+	sizeofIfmaMsghdr2Darwin15 = 0x14
+	sizeofIfDataDarwin15      = 0x60
+	sizeofIfData64Darwin15    = 0x80
+
+	sizeofRtMsghdrDarwin15  = 0x5c
+	sizeofRtMsghdr2Darwin15 = 0x5c
+	sizeofRtMetricsDarwin15 = 0x38
+)
diff --git a/libgo/go/golang_org/x/net/route/zsys_dragonfly.go b/libgo/go/golang_org/x/net/route/zsys_dragonfly.go
new file mode 100644
index 00000000000..dd36dece0f6
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_dragonfly.go
@@ -0,0 +1,92 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_dragonfly.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x11
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x1c
+
+	sysNET_RT_DUMP   = 0x1
+	sysNET_RT_FLAGS  = 0x2
+	sysNET_RT_IFLIST = 0x3
+	sysNET_RT_MAXID  = 0x4
+)
+
+const (
+	sysCTL_MAXNAME = 0xc
+
+	sysCTL_UNSPEC   = 0x0
+	sysCTL_KERN     = 0x1
+	sysCTL_VM       = 0x2
+	sysCTL_VFS      = 0x3
+	sysCTL_NET      = 0x4
+	sysCTL_DEBUG    = 0x5
+	sysCTL_HW       = 0x6
+	sysCTL_MACHDEP  = 0x7
+	sysCTL_USER     = 0x8
+	sysCTL_P1003_1B = 0x9
+	sysCTL_LWKT     = 0xa
+	sysCTL_MAXID    = 0xb
+)
+
+const (
+	sysRTM_VERSION = 0x6
+
+	sysRTM_ADD        = 0x1
+	sysRTM_DELETE     = 0x2
+	sysRTM_CHANGE     = 0x3
+	sysRTM_GET        = 0x4
+	sysRTM_LOSING     = 0x5
+	sysRTM_REDIRECT   = 0x6
+	sysRTM_MISS       = 0x7
+	sysRTM_LOCK       = 0x8
+	sysRTM_OLDADD     = 0x9
+	sysRTM_OLDDEL     = 0xa
+	sysRTM_RESOLVE    = 0xb
+	sysRTM_NEWADDR    = 0xc
+	sysRTM_DELADDR    = 0xd
+	sysRTM_IFINFO     = 0xe
+	sysRTM_NEWMADDR   = 0xf
+	sysRTM_DELMADDR   = 0x10
+	sysRTM_IFANNOUNCE = 0x11
+	sysRTM_IEEE80211  = 0x12
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+	sysRTA_MPLS1   = 0x100
+	sysRTA_MPLS2   = 0x200
+	sysRTA_MPLS3   = 0x400
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_MPLS1   = 0x8
+	sysRTAX_MPLS2   = 0x9
+	sysRTAX_MPLS3   = 0xa
+	sysRTAX_MAX     = 0xb
+)
+
+const (
+	sizeofIfMsghdrDragonFlyBSD4         = 0xb0
+	sizeofIfaMsghdrDragonFlyBSD4        = 0x14
+	sizeofIfmaMsghdrDragonFlyBSD4       = 0x10
+	sizeofIfAnnouncemsghdrDragonFlyBSD4 = 0x18
+
+	sizeofRtMsghdrDragonFlyBSD4  = 0x98
+	sizeofRtMetricsDragonFlyBSD4 = 0x70
+)
diff --git a/libgo/go/golang_org/x/net/route/zsys_freebsd_386.go b/libgo/go/golang_org/x/net/route/zsys_freebsd_386.go
new file mode 100644
index 00000000000..9bac2e3900f
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_freebsd_386.go
@@ -0,0 +1,120 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_freebsd.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x11
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x1c
+
+	sysNET_RT_DUMP     = 0x1
+	sysNET_RT_FLAGS    = 0x2
+	sysNET_RT_IFLIST   = 0x3
+	sysNET_RT_IFMALIST = 0x4
+	sysNET_RT_IFLISTL  = 0x5
+)
+
+const (
+	sysCTL_MAXNAME = 0x18
+
+	sysCTL_UNSPEC   = 0x0
+	sysCTL_KERN     = 0x1
+	sysCTL_VM       = 0x2
+	sysCTL_VFS      = 0x3
+	sysCTL_NET      = 0x4
+	sysCTL_DEBUG    = 0x5
+	sysCTL_HW       = 0x6
+	sysCTL_MACHDEP  = 0x7
+	sysCTL_USER     = 0x8
+	sysCTL_P1003_1B = 0x9
+)
+
+const (
+	sysRTM_VERSION = 0x5
+
+	sysRTM_ADD        = 0x1
+	sysRTM_DELETE     = 0x2
+	sysRTM_CHANGE     = 0x3
+	sysRTM_GET        = 0x4
+	sysRTM_LOSING     = 0x5
+	sysRTM_REDIRECT   = 0x6
+	sysRTM_MISS       = 0x7
+	sysRTM_LOCK       = 0x8
+	sysRTM_RESOLVE    = 0xb
+	sysRTM_NEWADDR    = 0xc
+	sysRTM_DELADDR    = 0xd
+	sysRTM_IFINFO     = 0xe
+	sysRTM_NEWMADDR   = 0xf
+	sysRTM_DELMADDR   = 0x10
+	sysRTM_IFANNOUNCE = 0x11
+	sysRTM_IEEE80211  = 0x12
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_MAX     = 0x8
+)
+
+const (
+	sizeofIfMsghdrlFreeBSD10        = 0x68
+	sizeofIfaMsghdrFreeBSD10        = 0x14
+	sizeofIfaMsghdrlFreeBSD10       = 0x6c
+	sizeofIfmaMsghdrFreeBSD10       = 0x10
+	sizeofIfAnnouncemsghdrFreeBSD10 = 0x18
+
+	sizeofRtMsghdrFreeBSD10  = 0x5c
+	sizeofRtMetricsFreeBSD10 = 0x38
+
+	sizeofIfMsghdrFreeBSD7  = 0x60
+	sizeofIfMsghdrFreeBSD8  = 0x60
+	sizeofIfMsghdrFreeBSD9  = 0x60
+	sizeofIfMsghdrFreeBSD10 = 0x64
+	sizeofIfMsghdrFreeBSD11 = 0xa8
+
+	sizeofIfDataFreeBSD7  = 0x50
+	sizeofIfDataFreeBSD8  = 0x50
+	sizeofIfDataFreeBSD9  = 0x50
+	sizeofIfDataFreeBSD10 = 0x54
+	sizeofIfDataFreeBSD11 = 0x98
+
+	// MODIFIED BY HAND FOR 386 EMULATION ON AMD64
+	// 386 EMULATION USES THE UNDERLYING RAW DATA LAYOUT
+
+	sizeofIfMsghdrlFreeBSD10Emu        = 0xb0
+	sizeofIfaMsghdrFreeBSD10Emu        = 0x14
+	sizeofIfaMsghdrlFreeBSD10Emu       = 0xb0
+	sizeofIfmaMsghdrFreeBSD10Emu       = 0x10
+	sizeofIfAnnouncemsghdrFreeBSD10Emu = 0x18
+
+	sizeofRtMsghdrFreeBSD10Emu  = 0x98
+	sizeofRtMetricsFreeBSD10Emu = 0x70
+
+	sizeofIfMsghdrFreeBSD7Emu  = 0xa8
+	sizeofIfMsghdrFreeBSD8Emu  = 0xa8
+	sizeofIfMsghdrFreeBSD9Emu  = 0xa8
+	sizeofIfMsghdrFreeBSD10Emu = 0xa8
+	sizeofIfMsghdrFreeBSD11Emu = 0xa8
+
+	sizeofIfDataFreeBSD7Emu  = 0x98
+	sizeofIfDataFreeBSD8Emu  = 0x98
+	sizeofIfDataFreeBSD9Emu  = 0x98
+	sizeofIfDataFreeBSD10Emu = 0x98
+	sizeofIfDataFreeBSD11Emu = 0x98
+)
diff --git a/libgo/go/golang_org/x/net/route/zsys_freebsd_amd64.go b/libgo/go/golang_org/x/net/route/zsys_freebsd_amd64.go
new file mode 100644
index 00000000000..b1920d7ac16
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_freebsd_amd64.go
@@ -0,0 +1,117 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_freebsd.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x11
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x1c
+
+	sysNET_RT_DUMP     = 0x1
+	sysNET_RT_FLAGS    = 0x2
+	sysNET_RT_IFLIST   = 0x3
+	sysNET_RT_IFMALIST = 0x4
+	sysNET_RT_IFLISTL  = 0x5
+)
+
+const (
+	sysCTL_MAXNAME = 0x18
+
+	sysCTL_UNSPEC   = 0x0
+	sysCTL_KERN     = 0x1
+	sysCTL_VM       = 0x2
+	sysCTL_VFS      = 0x3
+	sysCTL_NET      = 0x4
+	sysCTL_DEBUG    = 0x5
+	sysCTL_HW       = 0x6
+	sysCTL_MACHDEP  = 0x7
+	sysCTL_USER     = 0x8
+	sysCTL_P1003_1B = 0x9
+)
+
+const (
+	sysRTM_VERSION = 0x5
+
+	sysRTM_ADD        = 0x1
+	sysRTM_DELETE     = 0x2
+	sysRTM_CHANGE     = 0x3
+	sysRTM_GET        = 0x4
+	sysRTM_LOSING     = 0x5
+	sysRTM_REDIRECT   = 0x6
+	sysRTM_MISS       = 0x7
+	sysRTM_LOCK       = 0x8
+	sysRTM_RESOLVE    = 0xb
+	sysRTM_NEWADDR    = 0xc
+	sysRTM_DELADDR    = 0xd
+	sysRTM_IFINFO     = 0xe
+	sysRTM_NEWMADDR   = 0xf
+	sysRTM_DELMADDR   = 0x10
+	sysRTM_IFANNOUNCE = 0x11
+	sysRTM_IEEE80211  = 0x12
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_MAX     = 0x8
+)
+
+const (
+	sizeofIfMsghdrlFreeBSD10        = 0xb0
+	sizeofIfaMsghdrFreeBSD10        = 0x14
+	sizeofIfaMsghdrlFreeBSD10       = 0xb0
+	sizeofIfmaMsghdrFreeBSD10       = 0x10
+	sizeofIfAnnouncemsghdrFreeBSD10 = 0x18
+
+	sizeofRtMsghdrFreeBSD10  = 0x98
+	sizeofRtMetricsFreeBSD10 = 0x70
+
+	sizeofIfMsghdrFreeBSD7  = 0xa8
+	sizeofIfMsghdrFreeBSD8  = 0xa8
+	sizeofIfMsghdrFreeBSD9  = 0xa8
+	sizeofIfMsghdrFreeBSD10 = 0xa8
+	sizeofIfMsghdrFreeBSD11 = 0xa8
+
+	sizeofIfDataFreeBSD7  = 0x98
+	sizeofIfDataFreeBSD8  = 0x98
+	sizeofIfDataFreeBSD9  = 0x98
+	sizeofIfDataFreeBSD10 = 0x98
+	sizeofIfDataFreeBSD11 = 0x98
+
+	sizeofIfMsghdrlFreeBSD10Emu        = 0xb0
+	sizeofIfaMsghdrFreeBSD10Emu        = 0x14
+	sizeofIfaMsghdrlFreeBSD10Emu       = 0xb0
+	sizeofIfmaMsghdrFreeBSD10Emu       = 0x10
+	sizeofIfAnnouncemsghdrFreeBSD10Emu = 0x18
+
+	sizeofRtMsghdrFreeBSD10Emu  = 0x98
+	sizeofRtMetricsFreeBSD10Emu = 0x70
+
+	sizeofIfMsghdrFreeBSD7Emu  = 0xa8
+	sizeofIfMsghdrFreeBSD8Emu  = 0xa8
+	sizeofIfMsghdrFreeBSD9Emu  = 0xa8
+	sizeofIfMsghdrFreeBSD10Emu = 0xa8
+	sizeofIfMsghdrFreeBSD11Emu = 0xa8
+
+	sizeofIfDataFreeBSD7Emu  = 0x98
+	sizeofIfDataFreeBSD8Emu  = 0x98
+	sizeofIfDataFreeBSD9Emu  = 0x98
+	sizeofIfDataFreeBSD10Emu = 0x98
+	sizeofIfDataFreeBSD11Emu = 0x98
+)
diff --git a/libgo/go/golang_org/x/net/route/zsys_freebsd_arm.go b/libgo/go/golang_org/x/net/route/zsys_freebsd_arm.go
new file mode 100644
index 00000000000..a034d6fcbf2
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_freebsd_arm.go
@@ -0,0 +1,117 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_freebsd.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x11
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x1c
+
+	sysNET_RT_DUMP     = 0x1
+	sysNET_RT_FLAGS    = 0x2
+	sysNET_RT_IFLIST   = 0x3
+	sysNET_RT_IFMALIST = 0x4
+	sysNET_RT_IFLISTL  = 0x5
+)
+
+const (
+	sysCTL_MAXNAME = 0x18
+
+	sysCTL_UNSPEC   = 0x0
+	sysCTL_KERN     = 0x1
+	sysCTL_VM       = 0x2
+	sysCTL_VFS      = 0x3
+	sysCTL_NET      = 0x4
+	sysCTL_DEBUG    = 0x5
+	sysCTL_HW       = 0x6
+	sysCTL_MACHDEP  = 0x7
+	sysCTL_USER     = 0x8
+	sysCTL_P1003_1B = 0x9
+)
+
+const (
+	sysRTM_VERSION = 0x5
+
+	sysRTM_ADD        = 0x1
+	sysRTM_DELETE     = 0x2
+	sysRTM_CHANGE     = 0x3
+	sysRTM_GET        = 0x4
+	sysRTM_LOSING     = 0x5
+	sysRTM_REDIRECT   = 0x6
+	sysRTM_MISS       = 0x7
+	sysRTM_LOCK       = 0x8
+	sysRTM_RESOLVE    = 0xb
+	sysRTM_NEWADDR    = 0xc
+	sysRTM_DELADDR    = 0xd
+	sysRTM_IFINFO     = 0xe
+	sysRTM_NEWMADDR   = 0xf
+	sysRTM_DELMADDR   = 0x10
+	sysRTM_IFANNOUNCE = 0x11
+	sysRTM_IEEE80211  = 0x12
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_MAX     = 0x8
+)
+
+const (
+	sizeofIfMsghdrlFreeBSD10        = 0x68
+	sizeofIfaMsghdrFreeBSD10        = 0x14
+	sizeofIfaMsghdrlFreeBSD10       = 0x6c
+	sizeofIfmaMsghdrFreeBSD10       = 0x10
+	sizeofIfAnnouncemsghdrFreeBSD10 = 0x18
+
+	sizeofRtMsghdrFreeBSD10  = 0x5c
+	sizeofRtMetricsFreeBSD10 = 0x38
+
+	sizeofIfMsghdrFreeBSD7  = 0x70
+	sizeofIfMsghdrFreeBSD8  = 0x70
+	sizeofIfMsghdrFreeBSD9  = 0x70
+	sizeofIfMsghdrFreeBSD10 = 0x70
+	sizeofIfMsghdrFreeBSD11 = 0xa8
+
+	sizeofIfDataFreeBSD7  = 0x60
+	sizeofIfDataFreeBSD8  = 0x60
+	sizeofIfDataFreeBSD9  = 0x60
+	sizeofIfDataFreeBSD10 = 0x60
+	sizeofIfDataFreeBSD11 = 0x98
+
+	sizeofIfMsghdrlFreeBSD10Emu        = 0x68
+	sizeofIfaMsghdrFreeBSD10Emu        = 0x14
+	sizeofIfaMsghdrlFreeBSD10Emu       = 0x6c
+	sizeofIfmaMsghdrFreeBSD10Emu       = 0x10
+	sizeofIfAnnouncemsghdrFreeBSD10Emu = 0x18
+
+	sizeofRtMsghdrFreeBSD10Emu  = 0x5c
+	sizeofRtMetricsFreeBSD10Emu = 0x38
+
+	sizeofIfMsghdrFreeBSD7Emu  = 0x70
+	sizeofIfMsghdrFreeBSD8Emu  = 0x70
+	sizeofIfMsghdrFreeBSD9Emu  = 0x70
+	sizeofIfMsghdrFreeBSD10Emu = 0x70
+	sizeofIfMsghdrFreeBSD11Emu = 0xa8
+
+	sizeofIfDataFreeBSD7Emu  = 0x60
+	sizeofIfDataFreeBSD8Emu  = 0x60
+	sizeofIfDataFreeBSD9Emu  = 0x60
+	sizeofIfDataFreeBSD10Emu = 0x60
+	sizeofIfDataFreeBSD11Emu = 0x98
+)
diff --git a/libgo/go/golang_org/x/net/route/zsys_netbsd.go b/libgo/go/golang_org/x/net/route/zsys_netbsd.go
new file mode 100644
index 00000000000..aa4aad1613e
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_netbsd.go
@@ -0,0 +1,91 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_netbsd.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x22
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x18
+
+	sysNET_RT_DUMP   = 0x1
+	sysNET_RT_FLAGS  = 0x2
+	sysNET_RT_IFLIST = 0x5
+	sysNET_RT_MAXID  = 0x6
+)
+
+const (
+	sysCTL_MAXNAME = 0xc
+
+	sysCTL_UNSPEC   = 0x0
+	sysCTL_KERN     = 0x1
+	sysCTL_VM       = 0x2
+	sysCTL_VFS      = 0x3
+	sysCTL_NET      = 0x4
+	sysCTL_DEBUG    = 0x5
+	sysCTL_HW       = 0x6
+	sysCTL_MACHDEP  = 0x7
+	sysCTL_USER     = 0x8
+	sysCTL_DDB      = 0x9
+	sysCTL_PROC     = 0xa
+	sysCTL_VENDOR   = 0xb
+	sysCTL_EMUL     = 0xc
+	sysCTL_SECURITY = 0xd
+	sysCTL_MAXID    = 0xe
+)
+
+const (
+	sysRTM_VERSION = 0x4
+
+	sysRTM_ADD        = 0x1
+	sysRTM_DELETE     = 0x2
+	sysRTM_CHANGE     = 0x3
+	sysRTM_GET        = 0x4
+	sysRTM_LOSING     = 0x5
+	sysRTM_REDIRECT   = 0x6
+	sysRTM_MISS       = 0x7
+	sysRTM_LOCK       = 0x8
+	sysRTM_OLDADD     = 0x9
+	sysRTM_OLDDEL     = 0xa
+	sysRTM_RESOLVE    = 0xb
+	sysRTM_NEWADDR    = 0xc
+	sysRTM_DELADDR    = 0xd
+	sysRTM_IFANNOUNCE = 0x10
+	sysRTM_IEEE80211  = 0x11
+	sysRTM_SETGATE    = 0x12
+	sysRTM_LLINFO_UPD = 0x13
+	sysRTM_IFINFO     = 0x14
+	sysRTM_CHGADDR    = 0x15
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+	sysRTA_TAG     = 0x100
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_TAG     = 0x8
+	sysRTAX_MAX     = 0x9
+)
+
+const (
+	sizeofIfMsghdrNetBSD7         = 0x98
+	sizeofIfaMsghdrNetBSD7        = 0x18
+	sizeofIfAnnouncemsghdrNetBSD7 = 0x18
+
+	sizeofRtMsghdrNetBSD7  = 0x78
+	sizeofRtMetricsNetBSD7 = 0x50
+)
diff --git a/libgo/go/golang_org/x/net/route/zsys_openbsd.go b/libgo/go/golang_org/x/net/route/zsys_openbsd.go
new file mode 100644
index 00000000000..4fadc4e8fa1
--- /dev/null
+++ b/libgo/go/golang_org/x/net/route/zsys_openbsd.go
@@ -0,0 +1,80 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs defs_openbsd.go
+
+package route
+
+const (
+	sysAF_UNSPEC = 0x0
+	sysAF_INET   = 0x2
+	sysAF_ROUTE  = 0x11
+	sysAF_LINK   = 0x12
+	sysAF_INET6  = 0x18
+
+	sysNET_RT_DUMP    = 0x1
+	sysNET_RT_FLAGS   = 0x2
+	sysNET_RT_IFLIST  = 0x3
+	sysNET_RT_STATS   = 0x4
+	sysNET_RT_TABLE   = 0x5
+	sysNET_RT_IFNAMES = 0x6
+	sysNET_RT_MAXID   = 0x7
+)
+
+const (
+	sysCTL_MAXNAME = 0xc
+
+	sysCTL_UNSPEC  = 0x0
+	sysCTL_KERN    = 0x1
+	sysCTL_VM      = 0x2
+	sysCTL_FS      = 0x3
+	sysCTL_NET     = 0x4
+	sysCTL_DEBUG   = 0x5
+	sysCTL_HW      = 0x6
+	sysCTL_MACHDEP = 0x7
+	sysCTL_DDB     = 0x9
+	sysCTL_VFS     = 0xa
+	sysCTL_MAXID   = 0xb
+)
+
+const (
+	sysRTM_VERSION = 0x5
+
+	sysRTM_ADD        = 0x1
+	sysRTM_DELETE     = 0x2
+	sysRTM_CHANGE     = 0x3
+	sysRTM_GET        = 0x4
+	sysRTM_LOSING     = 0x5
+	sysRTM_REDIRECT   = 0x6
+	sysRTM_MISS       = 0x7
+	sysRTM_LOCK       = 0x8
+	sysRTM_RESOLVE    = 0xb
+	sysRTM_NEWADDR    = 0xc
+	sysRTM_DELADDR    = 0xd
+	sysRTM_IFINFO     = 0xe
+	sysRTM_IFANNOUNCE = 0xf
+	sysRTM_DESYNC     = 0x10
+
+	sysRTA_DST     = 0x1
+	sysRTA_GATEWAY = 0x2
+	sysRTA_NETMASK = 0x4
+	sysRTA_GENMASK = 0x8
+	sysRTA_IFP     = 0x10
+	sysRTA_IFA     = 0x20
+	sysRTA_AUTHOR  = 0x40
+	sysRTA_BRD     = 0x80
+	sysRTA_SRC     = 0x100
+	sysRTA_SRCMASK = 0x200
+	sysRTA_LABEL   = 0x400
+
+	sysRTAX_DST     = 0x0
+	sysRTAX_GATEWAY = 0x1
+	sysRTAX_NETMASK = 0x2
+	sysRTAX_GENMASK = 0x3
+	sysRTAX_IFP     = 0x4
+	sysRTAX_IFA     = 0x5
+	sysRTAX_AUTHOR  = 0x6
+	sysRTAX_BRD     = 0x7
+	sysRTAX_SRC     = 0x8
+	sysRTAX_SRCMASK = 0x9
+	sysRTAX_LABEL   = 0xa
+	sysRTAX_MAX     = 0xb
+)
diff --git a/libgo/go/hash/adler32/adler32.go b/libgo/go/hash/adler32/adler32.go
index 0c733f751af..21d6a2e1dc6 100644
--- a/libgo/go/hash/adler32/adler32.go
+++ b/libgo/go/hash/adler32/adler32.go
@@ -42,7 +42,7 @@ func New() hash.Hash32 {
 
 func (d *digest) Size() int { return Size }
 
-func (d *digest) BlockSize() int { return 1 }
+func (d *digest) BlockSize() int { return 4 }
 
 // Add p to the running checksum d.
 func update(d digest, p []byte) digest {
@@ -52,6 +52,17 @@ func update(d digest, p []byte) digest {
 		if len(p) > nmax {
 			p, q = p[:nmax], p[nmax:]
 		}
+		for len(p) >= 4 {
+			s1 += uint32(p[0])
+			s2 += s1
+			s1 += uint32(p[1])
+			s2 += s1
+			s1 += uint32(p[2])
+			s2 += s1
+			s1 += uint32(p[3])
+			s2 += s1
+			p = p[4:]
+		}
 		for _, x := range p {
 			s1 += uint32(x)
 			s2 += s1
diff --git a/libgo/go/hash/crc32/crc32.go b/libgo/go/hash/crc32/crc32.go
index dc5994885f9..c3ac7b80c3c 100644
--- a/libgo/go/hash/crc32/crc32.go
+++ b/libgo/go/hash/crc32/crc32.go
@@ -20,6 +20,9 @@ import (
 // The size of a CRC-32 checksum in bytes.
 const Size = 4
 
+// Use "slice by 8" when payload >= this value.
+const sliceBy8Cutoff = 16
+
 // Predefined polynomials.
 const (
 	// IEEE is by far and away the most common CRC-32 polynomial.
@@ -45,10 +48,12 @@ type Table [256]uint32
 // Castagnoli table so we can compare against it to find when the caller is
 // using this polynomial.
 var castagnoliTable *Table
+var castagnoliTable8 *slicing8Table
 var castagnoliOnce sync.Once
 
 func castagnoliInit() {
 	castagnoliTable = makeTable(Castagnoli)
+	castagnoliTable8 = makeTable8(Castagnoli)
 }
 
 // IEEETable is the table for the IEEE polynomial.
@@ -146,6 +151,9 @@ func updateSlicingBy8(crc uint32, tab *slicing8Table, p []byte) uint32 {
 		p = p[8:]
 	}
 	crc = ^crc
+	if len(p) == 0 {
+		return crc
+	}
 	return update(crc, &tab[0], p)
 }
 
@@ -178,4 +186,4 @@ func Checksum(data []byte, tab *Table) uint32 { return Update(0, tab, data) }
 
 // ChecksumIEEE returns the CRC-32 checksum of data
 // using the IEEE polynomial.
-func ChecksumIEEE(data []byte) uint32 { return Update(0, IEEETable, data) }
+func ChecksumIEEE(data []byte) uint32 { return updateIEEE(0, data) }
diff --git a/libgo/go/hash/crc32/crc32_amd64.go b/libgo/go/hash/crc32/crc32_amd64.go
index ab4e2b8c8cd..a0180a12dec 100644
--- a/libgo/go/hash/crc32/crc32_amd64.go
+++ b/libgo/go/hash/crc32/crc32_amd64.go
@@ -30,6 +30,10 @@ func updateCastagnoli(crc uint32, p []byte) uint32 {
 	if sse42 {
 		return castagnoliSSE42(crc, p)
 	}
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
+		return updateSlicingBy8(crc, castagnoliTable8, p)
+	}
 	return update(crc, castagnoliTable, p)
 }
 
@@ -44,8 +48,8 @@ func updateIEEE(crc uint32, p []byte) uint32 {
 		return crc
 	}
 
-	// only use slicing-by-8 when input is >= 4KB
-	if len(p) >= 4096 {
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
 		ieeeTable8Once.Do(func() {
 			ieeeTable8 = makeTable8(IEEE)
 		})
diff --git a/libgo/go/hash/crc32/crc32_amd64p32.go b/libgo/go/hash/crc32/crc32_amd64p32.go
index 067fbb162f9..1f6cd346431 100644
--- a/libgo/go/hash/crc32/crc32_amd64p32.go
+++ b/libgo/go/hash/crc32/crc32_amd64p32.go
@@ -22,12 +22,16 @@ func updateCastagnoli(crc uint32, p []byte) uint32 {
 	if sse42 {
 		return castagnoliSSE42(crc, p)
 	}
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
+		return updateSlicingBy8(crc, castagnoliTable8, p)
+	}
 	return update(crc, castagnoliTable, p)
 }
 
 func updateIEEE(crc uint32, p []byte) uint32 {
-	// only use slicing-by-8 when input is >= 4KB
-	if len(p) >= 4096 {
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
 		ieeeTable8Once.Do(func() {
 			ieeeTable8 = makeTable8(IEEE)
 		})
diff --git a/libgo/go/hash/crc32/crc32_generic.go b/libgo/go/hash/crc32/crc32_generic.go
index 8fc11a75db6..10a6367bc90 100644
--- a/libgo/go/hash/crc32/crc32_generic.go
+++ b/libgo/go/hash/crc32/crc32_generic.go
@@ -2,20 +2,24 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build 386 arm arm64 mips64 mips64le ppc64 ppc64le
+// +build !amd64,!amd64p32,!s390x
 
 package crc32
 
-// The file contains the generic version of updateCastagnoli which just calls
-// the software implementation.
+// This file contains the generic version of updateCastagnoli which does
+// slicing-by-8, or uses the fallback for very small sizes.
 
 func updateCastagnoli(crc uint32, p []byte) uint32 {
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
+		return updateSlicingBy8(crc, castagnoliTable8, p)
+	}
 	return update(crc, castagnoliTable, p)
 }
 
 func updateIEEE(crc uint32, p []byte) uint32 {
-	// only use slicing-by-8 when input is >= 4KB
-	if len(p) >= 4096 {
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
 		ieeeTable8Once.Do(func() {
 			ieeeTable8 = makeTable8(IEEE)
 		})
diff --git a/libgo/go/hash/crc32/crc32_s390x.go b/libgo/go/hash/crc32/crc32_s390x.go
new file mode 100644
index 00000000000..2f206903898
--- /dev/null
+++ b/libgo/go/hash/crc32/crc32_s390x.go
@@ -0,0 +1,101 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package crc32
+
+import (
+	"unsafe"
+)
+
+const (
+	vxMinLen    = 64
+	vxAlignment = 16
+	vxAlignMask = vxAlignment - 1
+)
+
+// hasVectorFacility reports whether the machine has the z/Architecture
+// vector facility installed and enabled.
+func hasVectorFacility() bool
+
+var hasVX = hasVectorFacility()
+
+// vectorizedCastagnoli implements CRC32 using vector instructions.
+// It is defined in crc32_s390x.s.
+//go:noescape
+func vectorizedCastagnoli(crc uint32, p []byte) uint32
+
+// vectorizedIEEE implements CRC32 using vector instructions.
+// It is defined in crc32_s390x.s.
+//go:noescape
+func vectorizedIEEE(crc uint32, p []byte) uint32
+
+func genericCastagnoli(crc uint32, p []byte) uint32 {
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
+		return updateSlicingBy8(crc, castagnoliTable8, p)
+	}
+	return update(crc, castagnoliTable, p)
+}
+
+func genericIEEE(crc uint32, p []byte) uint32 {
+	// Use slicing-by-8 on larger inputs.
+	if len(p) >= sliceBy8Cutoff {
+		ieeeTable8Once.Do(func() {
+			ieeeTable8 = makeTable8(IEEE)
+		})
+		return updateSlicingBy8(crc, ieeeTable8, p)
+	}
+	return update(crc, IEEETable, p)
+}
+
+// updateCastagnoli calculates the checksum of p using genericCastagnoli to
+// align the data appropriately for vectorCastagnoli. It avoids using
+// vectorCastagnoli entirely if the length of p is less than or equal to
+// vxMinLen.
+func updateCastagnoli(crc uint32, p []byte) uint32 {
+	// Use vectorized function if vector facility is available and
+	// data length is above threshold.
+	if hasVX && len(p) > vxMinLen {
+		pAddr := uintptr(unsafe.Pointer(&p[0]))
+		if pAddr&vxAlignMask != 0 {
+			prealign := vxAlignment - int(pAddr&vxAlignMask)
+			crc = genericCastagnoli(crc, p[:prealign])
+			p = p[prealign:]
+		}
+		aligned := len(p) & ^vxAlignMask
+		crc = vectorizedCastagnoli(crc, p[:aligned])
+		p = p[aligned:]
+		// process remaining data
+		if len(p) > 0 {
+			crc = genericCastagnoli(crc, p)
+		}
+		return crc
+	}
+	return genericCastagnoli(crc, p)
+}
+
+// updateIEEE calculates the checksum of p using genericIEEE to align the data
+// appropriately for vectorIEEE. It avoids using vectorIEEE entirely if the length
+// of p is less than or equal to vxMinLen.
+func updateIEEE(crc uint32, p []byte) uint32 {
+	// Use vectorized function if vector facility is available and
+	// data length is above threshold.
+	if hasVX && len(p) > vxMinLen {
+		pAddr := uintptr(unsafe.Pointer(&p[0]))
+		if pAddr&vxAlignMask != 0 {
+			prealign := vxAlignment - int(pAddr&vxAlignMask)
+			crc = genericIEEE(crc, p[:prealign])
+			p = p[prealign:]
+		}
+		aligned := len(p) & ^vxAlignMask
+		crc = vectorizedIEEE(crc, p[:aligned])
+		p = p[aligned:]
+		// process remaining data
+		if len(p) > 0 {
+			crc = genericIEEE(crc, p)
+		}
+		return crc
+	}
+	return genericIEEE(crc, p)
+}
diff --git a/libgo/go/hash/crc32/crc32_test.go b/libgo/go/hash/crc32/crc32_test.go
index 1ca3ac2a270..e2b3557828c 100644
--- a/libgo/go/hash/crc32/crc32_test.go
+++ b/libgo/go/hash/crc32/crc32_test.go
@@ -5,6 +5,7 @@
 package crc32
 
 import (
+	"hash"
 	"io"
 	"testing"
 )
@@ -81,49 +82,51 @@ func TestGolden(t *testing.T) {
 	}
 }
 
-func BenchmarkIEEECrc1KB(b *testing.B) {
-	b.SetBytes(1024)
-	data := make([]byte, 1024)
-	for i := range data {
-		data[i] = byte(i)
-	}
-	h := NewIEEE()
-	in := make([]byte, 0, h.Size())
+func BenchmarkIEEECrc40B(b *testing.B) {
+	benchmark(b, NewIEEE(), 40)
+}
 
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		h.Reset()
-		h.Write(data)
-		h.Sum(in)
-	}
+func BenchmarkIEEECrc1KB(b *testing.B) {
+	benchmark(b, NewIEEE(), 1<<10)
 }
 
 func BenchmarkIEEECrc4KB(b *testing.B) {
-	b.SetBytes(4096)
-	data := make([]byte, 4096)
-	for i := range data {
-		data[i] = byte(i)
-	}
-	h := NewIEEE()
-	in := make([]byte, 0, h.Size())
+	benchmark(b, NewIEEE(), 4<<10)
+}
 
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		h.Reset()
-		h.Write(data)
-		h.Sum(in)
-	}
+func BenchmarkIEEECrc32KB(b *testing.B) {
+	benchmark(b, NewIEEE(), 32<<10)
+}
+
+func BenchmarkCastagnoliCrc40B(b *testing.B) {
+	benchmark(b, New(MakeTable(Castagnoli)), 40)
 }
 
 func BenchmarkCastagnoliCrc1KB(b *testing.B) {
-	b.SetBytes(1024)
-	data := make([]byte, 1024)
+	benchmark(b, New(MakeTable(Castagnoli)), 1<<10)
+}
+
+func BenchmarkCastagnoliCrc4KB(b *testing.B) {
+	benchmark(b, New(MakeTable(Castagnoli)), 4<<10)
+}
+
+func BenchmarkCastagnoliCrc32KB(b *testing.B) {
+	benchmark(b, New(MakeTable(Castagnoli)), 32<<10)
+}
+
+func benchmark(b *testing.B, h hash.Hash32, n int64) {
+	b.SetBytes(n)
+	data := make([]byte, n)
 	for i := range data {
 		data[i] = byte(i)
 	}
-	h := New(MakeTable(Castagnoli))
 	in := make([]byte, 0, h.Size())
 
+	// Warm up
+	h.Reset()
+	h.Write(data)
+	h.Sum(in)
+
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		h.Reset()
diff --git a/libgo/go/hash/crc64/crc64.go b/libgo/go/hash/crc64/crc64.go
index 54cc56055e4..e939c2a06ac 100644
--- a/libgo/go/hash/crc64/crc64.go
+++ b/libgo/go/hash/crc64/crc64.go
@@ -24,9 +24,25 @@ const (
 // Table is a 256-word table representing the polynomial for efficient processing.
 type Table [256]uint64
 
+var (
+	slicing8TableISO  = makeSlicingBy8Table(makeTable(ISO))
+	slicing8TableECMA = makeSlicingBy8Table(makeTable(ECMA))
+)
+
 // MakeTable returns a Table constructed from the specified polynomial.
 // The contents of this Table must not be modified.
 func MakeTable(poly uint64) *Table {
+	switch poly {
+	case ISO:
+		return &slicing8TableISO[0]
+	case ECMA:
+		return &slicing8TableECMA[0]
+	default:
+		return makeTable(poly)
+	}
+}
+
+func makeTable(poly uint64) *Table {
 	t := new(Table)
 	for i := 0; i < 256; i++ {
 		crc := uint64(i)
@@ -42,6 +58,19 @@ func MakeTable(poly uint64) *Table {
 	return t
 }
 
+func makeSlicingBy8Table(t *Table) *[8]Table {
+	var helperTable [8]Table
+	helperTable[0] = *t
+	for i := 0; i < 256; i++ {
+		crc := t[i]
+		for j := 1; j < 8; j++ {
+			crc = t[crc&0xff] ^ (crc >> 8)
+			helperTable[j][i] = crc
+		}
+	}
+	return &helperTable
+}
+
 // digest represents the partial evaluation of a checksum.
 type digest struct {
 	crc uint64
@@ -61,6 +90,35 @@ func (d *digest) Reset() { d.crc = 0 }
 
 func update(crc uint64, tab *Table, p []byte) uint64 {
 	crc = ^crc
+	// Table comparison is somewhat expensive, so avoid it for small sizes
+	for len(p) >= 64 {
+		var helperTable *[8]Table
+		if *tab == slicing8TableECMA[0] {
+			helperTable = slicing8TableECMA
+		} else if *tab == slicing8TableISO[0] {
+			helperTable = slicing8TableISO
+			// For smaller sizes creating extended table takes too much time
+		} else if len(p) > 16384 {
+			helperTable = makeSlicingBy8Table(tab)
+		} else {
+			break
+		}
+		// Update using slicing-by-8
+		for len(p) > 8 {
+			crc ^= uint64(p[0]) | uint64(p[1])<<8 | uint64(p[2])<<16 | uint64(p[3])<<24 |
+				uint64(p[4])<<32 | uint64(p[5])<<40 | uint64(p[6])<<48 | uint64(p[7])<<56
+			crc = helperTable[7][crc&0xff] ^
+				helperTable[6][(crc>>8)&0xff] ^
+				helperTable[5][(crc>>16)&0xff] ^
+				helperTable[4][(crc>>24)&0xff] ^
+				helperTable[3][(crc>>32)&0xff] ^
+				helperTable[2][(crc>>40)&0xff] ^
+				helperTable[1][(crc>>48)&0xff] ^
+				helperTable[0][crc>>56]
+			p = p[8:]
+		}
+	}
+	// For reminders or small sizes
 	for _, v := range p {
 		crc = tab[byte(crc)^v] ^ (crc >> 8)
 	}
diff --git a/libgo/go/hash/crc64/crc64_test.go b/libgo/go/hash/crc64/crc64_test.go
index 81a87b56e35..480b150e132 100644
--- a/libgo/go/hash/crc64/crc64_test.go
+++ b/libgo/go/hash/crc64/crc64_test.go
@@ -10,66 +10,75 @@ import (
 )
 
 type test struct {
-	out uint64
-	in  string
+	outISO  uint64
+	outECMA uint64
+	in      string
 }
 
 var golden = []test{
-	{0x0, ""},
-	{0x3420000000000000, "a"},
-	{0x36c4200000000000, "ab"},
-	{0x3776c42000000000, "abc"},
-	{0x336776c420000000, "abcd"},
-	{0x32d36776c4200000, "abcde"},
-	{0x3002d36776c42000, "abcdef"},
-	{0x31b002d36776c420, "abcdefg"},
-	{0xe21b002d36776c4, "abcdefgh"},
-	{0x8b6e21b002d36776, "abcdefghi"},
-	{0x7f5b6e21b002d367, "abcdefghij"},
-	{0x8ec0e7c835bf9cdf, "Discard medicine more than two years old."},
-	{0xc7db1759e2be5ab4, "He who has a shady past knows that nice guys finish last."},
-	{0xfbf9d9603a6fa020, "I wouldn't marry him with a ten foot pole."},
-	{0xeafc4211a6daa0ef, "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
-	{0x3e05b21c7a4dc4da, "The days of the digital watch are numbered.  -Tom Stoppard"},
-	{0x5255866ad6ef28a6, "Nepal premier won't resign."},
-	{0x8a79895be1e9c361, "For every action there is an equal and opposite government program."},
-	{0x8878963a649d4916, "His money is twice tainted: 'taint yours and 'taint mine."},
-	{0xa7b9d53ea87eb82f, "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
-	{0xdb6805c0966a2f9c, "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
-	{0xf3553c65dacdadd2, "size:  a.out:  bad magic"},
-	{0x9d5e034087a676b9, "The major problem is with sendmail.  -Mark Horton"},
-	{0xa6db2d7f8da96417, "Give me a rock, paper and scissors and I will move the world.  CCFestoon"},
-	{0x325e00cd2fe819f9, "If the enemy is within range, then so are you."},
-	{0x88c6600ce58ae4c6, "It's well we cannot hear the screams/That we create in others' dreams."},
-	{0x28c4a3f3b769e078, "You remind me of a TV show, but that's all right: I watch it anyway."},
-	{0xa698a34c9d9f1dca, "C is as portable as Stonehedge!!"},
-	{0xf6c1e2a8c26c5cfc, "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
-	{0xd402559dfe9b70c, "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule"},
-	{0xdb6efff26aa94946, "How can you write a big system without C++?  -Paul Glick"},
+	{0x0, 0x0, ""},
+	{0x3420000000000000, 0x330284772e652b05, "a"},
+	{0x36c4200000000000, 0xbc6573200e84b046, "ab"},
+	{0x3776c42000000000, 0x2cd8094a1a277627, "abc"},
+	{0x336776c420000000, 0x3c9d28596e5960ba, "abcd"},
+	{0x32d36776c4200000, 0x40bdf58fb0895f2, "abcde"},
+	{0x3002d36776c42000, 0xd08e9f8545a700f4, "abcdef"},
+	{0x31b002d36776c420, 0xec20a3a8cc710e66, "abcdefg"},
+	{0xe21b002d36776c4, 0x67b4f30a647a0c59, "abcdefgh"},
+	{0x8b6e21b002d36776, 0x9966f6c89d56ef8e, "abcdefghi"},
+	{0x7f5b6e21b002d367, 0x32093a2ecd5773f4, "abcdefghij"},
+	{0x8ec0e7c835bf9cdf, 0x8a0825223ea6d221, "Discard medicine more than two years old."},
+	{0xc7db1759e2be5ab4, 0x8562c0ac2ab9a00d, "He who has a shady past knows that nice guys finish last."},
+	{0xfbf9d9603a6fa020, 0x3ee2a39c083f38b4, "I wouldn't marry him with a ten foot pole."},
+	{0xeafc4211a6daa0ef, 0x1f603830353e518a, "Free! Free!/A trip/to Mars/for 900/empty jars/Burma Shave"},
+	{0x3e05b21c7a4dc4da, 0x2fd681d7b2421fd, "The days of the digital watch are numbered.  -Tom Stoppard"},
+	{0x5255866ad6ef28a6, 0x790ef2b16a745a41, "Nepal premier won't resign."},
+	{0x8a79895be1e9c361, 0x3ef8f06daccdcddf, "For every action there is an equal and opposite government program."},
+	{0x8878963a649d4916, 0x49e41b2660b106d, "His money is twice tainted: 'taint yours and 'taint mine."},
+	{0xa7b9d53ea87eb82f, 0x561cc0cfa235ac68, "There is no reason for any individual to have a computer in their home. -Ken Olsen, 1977"},
+	{0xdb6805c0966a2f9c, 0xd4fe9ef082e69f59, "It's a tiny change to the code and not completely disgusting. - Bob Manchek"},
+	{0xf3553c65dacdadd2, 0xe3b5e46cd8d63a4d, "size:  a.out:  bad magic"},
+	{0x9d5e034087a676b9, 0x865aaf6b94f2a051, "The major problem is with sendmail.  -Mark Horton"},
+	{0xa6db2d7f8da96417, 0x7eca10d2f8136eb4, "Give me a rock, paper and scissors and I will move the world.  CCFestoon"},
+	{0x325e00cd2fe819f9, 0xd7dd118c98e98727, "If the enemy is within range, then so are you."},
+	{0x88c6600ce58ae4c6, 0x70fb33c119c29318, "It's well we cannot hear the screams/That we create in others' dreams."},
+	{0x28c4a3f3b769e078, 0x57c891e39a97d9b7, "You remind me of a TV show, but that's all right: I watch it anyway."},
+	{0xa698a34c9d9f1dca, 0xa1f46ba20ad06eb7, "C is as portable as Stonehedge!!"},
+	{0xf6c1e2a8c26c5cfc, 0x7ad25fafa1710407, "Even if I could be Shakespeare, I think I should still choose to be Faraday. - A. Huxley"},
+	{0xd402559dfe9b70c, 0x73cef1666185c13f, "The fugacity of a constituent in a mixture of gases at a given temperature is proportional to its mole fraction.  Lewis-Randall Rule"},
+	{0xdb6efff26aa94946, 0xb41858f73c389602, "How can you write a big system without C++?  -Paul Glick"},
+	{0xe7fcf1006b503b61, 0x27db187fc15bbc72, "This is a test of the emergency broadcast system."},
 }
 
-var tab = MakeTable(ISO)
-
 func TestGolden(t *testing.T) {
+	tabISO := MakeTable(ISO)
+	tabECMA := MakeTable(ECMA)
 	for i := 0; i < len(golden); i++ {
 		g := golden[i]
-		c := New(tab)
+		c := New(tabISO)
 		io.WriteString(c, g.in)
 		s := c.Sum64()
-		if s != g.out {
-			t.Errorf("crc64(%s) = 0x%x want 0x%x", g.in, s, g.out)
+		if s != g.outISO {
+			t.Errorf("ISO crc64(%s) = 0x%x want 0x%x", g.in, s, g.outISO)
+			t.FailNow()
+		}
+		c = New(tabECMA)
+		io.WriteString(c, g.in)
+		s = c.Sum64()
+		if s != g.outECMA {
+			t.Errorf("ECMA crc64(%s) = 0x%x want 0x%x", g.in, s, g.outECMA)
 			t.FailNow()
 		}
 	}
 }
 
-func BenchmarkCrc64KB(b *testing.B) {
-	b.SetBytes(1024)
-	data := make([]byte, 1024)
+func bench(b *testing.B, poly uint64, size int64) {
+	b.SetBytes(size)
+	data := make([]byte, size)
 	for i := range data {
 		data[i] = byte(i)
 	}
-	h := New(tab)
+	h := New(MakeTable(poly))
 	in := make([]byte, 0, h.Size())
 
 	b.ResetTimer()
@@ -79,3 +88,24 @@ func BenchmarkCrc64KB(b *testing.B) {
 		h.Sum(in)
 	}
 }
+
+func BenchmarkCrc64(b *testing.B) {
+	b.Run("ISO64KB", func(b *testing.B) {
+		bench(b, ISO, 64<<10)
+	})
+	b.Run("ISO4KB", func(b *testing.B) {
+		bench(b, ISO, 4<<10)
+	})
+	b.Run("ISO1KB", func(b *testing.B) {
+		bench(b, ISO, 1<<10)
+	})
+	b.Run("ECMA64KB", func(b *testing.B) {
+		bench(b, ECMA, 64<<10)
+	})
+	b.Run("Random64KB", func(b *testing.B) {
+		bench(b, 0x777, 64<<10)
+	})
+	b.Run("Random16KB", func(b *testing.B) {
+		bench(b, 0x777, 16<<10)
+	})
+}
diff --git a/libgo/go/html/escape.go b/libgo/go/html/escape.go
index ab6fd1c7b4b..8dd1f4ad2f6 100644
--- a/libgo/go/html/escape.go
+++ b/libgo/go/html/escape.go
@@ -10,10 +10,6 @@ import (
 	"unicode/utf8"
 )
 
-type writer interface {
-	WriteString(string) (int, error)
-}
-
 // These replacements permit compatibility with old numeric entities that
 // assumed Windows-1252 encoding.
 // http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#consume-a-character-reference
@@ -185,7 +181,7 @@ func EscapeString(s string) string {
 
 // UnescapeString unescapes entities like "&lt;" to become "<". It unescapes a
 // larger range of entities than EscapeString escapes. For example, "&aacute;"
-// unescapes to "á", as does "&#225;" and "&xE1;".
+// unescapes to "á", as does "&#225;" and "&#xE1;".
 // UnescapeString(EscapeString(s)) == s always holds, but the converse isn't
 // always true.
 func UnescapeString(s string) string {
diff --git a/libgo/go/html/template/content.go b/libgo/go/html/template/content.go
index 3715ed5c938..2e14bd1231f 100644
--- a/libgo/go/html/template/content.go
+++ b/libgo/go/html/template/content.go
@@ -18,16 +18,28 @@ type (
 	//   4. The CSS3 value production, such as `rgba(0, 0, 255, 127)`.
 	// See http://www.w3.org/TR/css3-syntax/#parsing and
 	// https://web.archive.org/web/20090211114933/http://w3.org/TR/css3-syntax#style
+	//
+	// Use of this type presents a security risk:
+	// the encapsulated content should come from a trusted source,
+	// as it will be included verbatim in the template output.
 	CSS string
 
 	// HTML encapsulates a known safe HTML document fragment.
 	// It should not be used for HTML from a third-party, or HTML with
 	// unclosed tags or comments. The outputs of a sound HTML sanitizer
 	// and a template escaped by this package are fine for use with HTML.
+	//
+	// Use of this type presents a security risk:
+	// the encapsulated content should come from a trusted source,
+	// as it will be included verbatim in the template output.
 	HTML string
 
 	// HTMLAttr encapsulates an HTML attribute from a trusted source,
 	// for example, ` dir="ltr"`.
+	//
+	// Use of this type presents a security risk:
+	// the encapsulated content should come from a trusted source,
+	// as it will be included verbatim in the template output.
 	HTMLAttr string
 
 	// JS encapsulates a known safe EcmaScript5 Expression, for example,
@@ -37,6 +49,15 @@ type (
 	// statement/expression ambiguity as when passing an expression like
 	// "{ foo: bar() }\n['foo']()", which is both a valid Expression and a
 	// valid Program with a very different meaning.
+	//
+	// Use of this type presents a security risk:
+	// the encapsulated content should come from a trusted source,
+	// as it will be included verbatim in the template output.
+	//
+	// Using JS to include valid but untrusted JSON is not safe.
+	// A safe alternative is to parse the JSON with json.Unmarshal and then
+	// pass the resultant object into the template, where it will be
+	// converted to sanitized JSON when presented in a JavaScript context.
 	JS string
 
 	// JSStr encapsulates a sequence of characters meant to be embedded
@@ -46,6 +67,10 @@ type (
 	//                    | EscapeSequence
 	// Note that LineContinuations are not allowed.
 	// JSStr("foo\\nbar") is fine, but JSStr("foo\\\nbar") is not.
+	//
+	// Use of this type presents a security risk:
+	// the encapsulated content should come from a trusted source,
+	// as it will be included verbatim in the template output.
 	JSStr string
 
 	// URL encapsulates a known safe URL or URL substring (see RFC 3986).
@@ -53,6 +78,10 @@ type (
 	// from a trusted source should go in the page, but by default dynamic
 	// `javascript:` URLs are filtered out since they are a frequently
 	// exploited injection vector.
+	//
+	// Use of this type presents a security risk:
+	// the encapsulated content should come from a trusted source,
+	// as it will be included verbatim in the template output.
 	URL string
 )
 
diff --git a/libgo/go/html/template/css.go b/libgo/go/html/template/css.go
index 318464835fa..9154d8636da 100644
--- a/libgo/go/html/template/css.go
+++ b/libgo/go/html/template/css.go
@@ -243,13 +243,13 @@ func cssValueFilter(args ...interface{}) string {
 				return filterFailsafe
 			}
 		default:
-			if c < 0x80 && isCSSNmchar(rune(c)) {
+			if c < utf8.RuneSelf && isCSSNmchar(rune(c)) {
 				id = append(id, c)
 			}
 		}
 	}
 	id = bytes.ToLower(id)
-	if bytes.Index(id, expressionBytes) != -1 || bytes.Index(id, mozBindingBytes) != -1 {
+	if bytes.Contains(id, expressionBytes) || bytes.Contains(id, mozBindingBytes) {
 		return filterFailsafe
 	}
 	return string(b)
diff --git a/libgo/go/html/template/doc.go b/libgo/go/html/template/doc.go
index 1827403aa38..e1e9cad0af7 100644
--- a/libgo/go/html/template/doc.go
+++ b/libgo/go/html/template/doc.go
@@ -166,7 +166,7 @@ that would have been produced if {{.}} was a regular string.
 
 Security Model
 
-http://js-quasis-libraries-and-repl.googlecode.com/svn/trunk/safetemplate.html#problem_definition defines "safe" as used by this package.
+https://rawgit.com/mikesamuel/sanitized-jquery-templates/trunk/safetemplate.html#problem_definition defines "safe" as used by this package.
 
 This package assumes that template authors are trusted, that Execute's data
 parameter is not, and seeks to preserve the properties below in the face
diff --git a/libgo/go/html/template/error.go b/libgo/go/html/template/error.go
index 8f99e1b9624..5637384bd86 100644
--- a/libgo/go/html/template/error.go
+++ b/libgo/go/html/template/error.go
@@ -164,7 +164,7 @@ const (
 	//   different context than an earlier pass, there is no single context.
 	//   In the example, there is missing a quote, so it is not clear
 	//   whether {{.}} is meant to be inside a JS string or in a JS value
-	//   context.  The second iteration would produce something like
+	//   context. The second iteration would produce something like
 	//
 	//     <script>var x = ['firstValue,'secondValue]</script>
 	ErrRangeLoopReentry
diff --git a/libgo/go/html/template/escape.go b/libgo/go/html/template/escape.go
index 3c183405478..8f2fe460de6 100644
--- a/libgo/go/html/template/escape.go
+++ b/libgo/go/html/template/escape.go
@@ -15,8 +15,8 @@ import (
 
 // escapeTemplate rewrites the named template, which must be
 // associated with t, to guarantee that the output of any of the named
-// templates is properly escaped.  If no error is returned, then the named templates have
-// been modified.  Otherwise the named templates have been rendered
+// templates is properly escaped. If no error is returned, then the named templates have
+// been modified. Otherwise the named templates have been rendered
 // unusable.
 func escapeTemplate(tmpl *Template, node parse.Node, name string) error {
 	e := newEscaper(tmpl)
@@ -46,30 +46,30 @@ func escapeTemplate(tmpl *Template, node parse.Node, name string) error {
 
 // funcMap maps command names to functions that render their inputs safe.
 var funcMap = template.FuncMap{
-	"html_template_attrescaper":     attrEscaper,
-	"html_template_commentescaper":  commentEscaper,
-	"html_template_cssescaper":      cssEscaper,
-	"html_template_cssvaluefilter":  cssValueFilter,
-	"html_template_htmlnamefilter":  htmlNameFilter,
-	"html_template_htmlescaper":     htmlEscaper,
-	"html_template_jsregexpescaper": jsRegexpEscaper,
-	"html_template_jsstrescaper":    jsStrEscaper,
-	"html_template_jsvalescaper":    jsValEscaper,
-	"html_template_nospaceescaper":  htmlNospaceEscaper,
-	"html_template_rcdataescaper":   rcdataEscaper,
-	"html_template_urlescaper":      urlEscaper,
-	"html_template_urlfilter":       urlFilter,
-	"html_template_urlnormalizer":   urlNormalizer,
+	"_html_template_attrescaper":     attrEscaper,
+	"_html_template_commentescaper":  commentEscaper,
+	"_html_template_cssescaper":      cssEscaper,
+	"_html_template_cssvaluefilter":  cssValueFilter,
+	"_html_template_htmlnamefilter":  htmlNameFilter,
+	"_html_template_htmlescaper":     htmlEscaper,
+	"_html_template_jsregexpescaper": jsRegexpEscaper,
+	"_html_template_jsstrescaper":    jsStrEscaper,
+	"_html_template_jsvalescaper":    jsValEscaper,
+	"_html_template_nospaceescaper":  htmlNospaceEscaper,
+	"_html_template_rcdataescaper":   rcdataEscaper,
+	"_html_template_urlescaper":      urlEscaper,
+	"_html_template_urlfilter":       urlFilter,
+	"_html_template_urlnormalizer":   urlNormalizer,
 }
 
 // equivEscapers matches contextual escapers to equivalent template builtins.
 var equivEscapers = map[string]string{
-	"html_template_attrescaper":    "html",
-	"html_template_htmlescaper":    "html",
-	"html_template_nospaceescaper": "html",
-	"html_template_rcdataescaper":  "html",
-	"html_template_urlescaper":     "urlquery",
-	"html_template_urlnormalizer":  "urlquery",
+	"_html_template_attrescaper":    "html",
+	"_html_template_htmlescaper":    "html",
+	"_html_template_nospaceescaper": "html",
+	"_html_template_rcdataescaper":  "html",
+	"_html_template_urlescaper":     "urlquery",
+	"_html_template_urlnormalizer":  "urlquery",
 }
 
 // escaper collects type inferences about templates and changes needed to make
@@ -147,17 +147,17 @@ func (e *escaper) escapeAction(c context, n *parse.ActionNode) context {
 	case stateURL, stateCSSDqStr, stateCSSSqStr, stateCSSDqURL, stateCSSSqURL, stateCSSURL:
 		switch c.urlPart {
 		case urlPartNone:
-			s = append(s, "html_template_urlfilter")
+			s = append(s, "_html_template_urlfilter")
 			fallthrough
 		case urlPartPreQuery:
 			switch c.state {
 			case stateCSSDqStr, stateCSSSqStr:
-				s = append(s, "html_template_cssescaper")
+				s = append(s, "_html_template_cssescaper")
 			default:
-				s = append(s, "html_template_urlnormalizer")
+				s = append(s, "_html_template_urlnormalizer")
 			}
 		case urlPartQueryOrFrag:
-			s = append(s, "html_template_urlescaper")
+			s = append(s, "_html_template_urlescaper")
 		case urlPartUnknown:
 			return context{
 				state: stateError,
@@ -167,27 +167,27 @@ func (e *escaper) escapeAction(c context, n *parse.ActionNode) context {
 			panic(c.urlPart.String())
 		}
 	case stateJS:
-		s = append(s, "html_template_jsvalescaper")
+		s = append(s, "_html_template_jsvalescaper")
 		// A slash after a value starts a div operator.
 		c.jsCtx = jsCtxDivOp
 	case stateJSDqStr, stateJSSqStr:
-		s = append(s, "html_template_jsstrescaper")
+		s = append(s, "_html_template_jsstrescaper")
 	case stateJSRegexp:
-		s = append(s, "html_template_jsregexpescaper")
+		s = append(s, "_html_template_jsregexpescaper")
 	case stateCSS:
-		s = append(s, "html_template_cssvaluefilter")
+		s = append(s, "_html_template_cssvaluefilter")
 	case stateText:
-		s = append(s, "html_template_htmlescaper")
+		s = append(s, "_html_template_htmlescaper")
 	case stateRCDATA:
-		s = append(s, "html_template_rcdataescaper")
+		s = append(s, "_html_template_rcdataescaper")
 	case stateAttr:
 		// Handled below in delim check.
 	case stateAttrName, stateTag:
 		c.state = stateAttrName
-		s = append(s, "html_template_htmlnamefilter")
+		s = append(s, "_html_template_htmlnamefilter")
 	default:
 		if isComment(c.state) {
-			s = append(s, "html_template_commentescaper")
+			s = append(s, "_html_template_commentescaper")
 		} else {
 			panic("unexpected state " + c.state.String())
 		}
@@ -196,9 +196,9 @@ func (e *escaper) escapeAction(c context, n *parse.ActionNode) context {
 	case delimNone:
 		// No extra-escaping needed for raw text content.
 	case delimSpaceOrTagEnd:
-		s = append(s, "html_template_nospaceescaper")
+		s = append(s, "_html_template_nospaceescaper")
 	default:
-		s = append(s, "html_template_attrescaper")
+		s = append(s, "_html_template_attrescaper")
 	}
 	e.editActionNode(n, s)
 	return c
@@ -276,22 +276,22 @@ func ensurePipelineContains(p *parse.PipeNode, s []string) {
 // redundantFuncs[a][b] implies that funcMap[b](funcMap[a](x)) == funcMap[a](x)
 // for all x.
 var redundantFuncs = map[string]map[string]bool{
-	"html_template_commentescaper": {
-		"html_template_attrescaper":    true,
-		"html_template_nospaceescaper": true,
-		"html_template_htmlescaper":    true,
+	"_html_template_commentescaper": {
+		"_html_template_attrescaper":    true,
+		"_html_template_nospaceescaper": true,
+		"_html_template_htmlescaper":    true,
 	},
-	"html_template_cssescaper": {
-		"html_template_attrescaper": true,
+	"_html_template_cssescaper": {
+		"_html_template_attrescaper": true,
 	},
-	"html_template_jsregexpescaper": {
-		"html_template_attrescaper": true,
+	"_html_template_jsregexpescaper": {
+		"_html_template_attrescaper": true,
 	},
-	"html_template_jsstrescaper": {
-		"html_template_attrescaper": true,
+	"_html_template_jsstrescaper": {
+		"_html_template_attrescaper": true,
 	},
-	"html_template_urlescaper": {
-		"html_template_urlnormalizer": true,
+	"_html_template_urlescaper": {
+		"_html_template_urlnormalizer": true,
 	},
 }
 
diff --git a/libgo/go/html/template/escape_test.go b/libgo/go/html/template/escape_test.go
index 707394e3b02..023ee57d597 100644
--- a/libgo/go/html/template/escape_test.go
+++ b/libgo/go/html/template/escape_test.go
@@ -990,7 +990,7 @@ func TestErrors(t *testing.T) {
 			}
 			continue
 		}
-		if strings.Index(got, test.err) == -1 {
+		if !strings.Contains(got, test.err) {
 			t.Errorf("input=%q: error\n\t%q\ndoes not contain expected string\n\t%q", test.input, got, test.err)
 			continue
 		}
diff --git a/libgo/go/html/template/examplefiles_test.go b/libgo/go/html/template/examplefiles_test.go
new file mode 100644
index 00000000000..ffca8d5a787
--- /dev/null
+++ b/libgo/go/html/template/examplefiles_test.go
@@ -0,0 +1,228 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package template_test
+
+import (
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"text/template"
+)
+
+// templateFile defines the contents of a template to be stored in a file, for testing.
+type templateFile struct {
+	name     string
+	contents string
+}
+
+func createTestDir(files []templateFile) string {
+	dir, err := ioutil.TempDir("", "template")
+	if err != nil {
+		log.Fatal(err)
+	}
+	for _, file := range files {
+		f, err := os.Create(filepath.Join(dir, file.name))
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer f.Close()
+		_, err = io.WriteString(f, file.contents)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+	return dir
+}
+
+// The following example is duplicated in text/template; keep them in sync.
+
+// Here we demonstrate loading a set of templates from a directory.
+func ExampleTemplate_glob() {
+	// Here we create a temporary directory and populate it with our sample
+	// template definition files; usually the template files would already
+	// exist in some location known to the program.
+	dir := createTestDir([]templateFile{
+		// T0.tmpl is a plain template file that just invokes T1.
+		{"T0.tmpl", `T0 invokes T1: ({{template "T1"}})`},
+		// T1.tmpl defines a template, T1 that invokes T2.
+		{"T1.tmpl", `{{define "T1"}}T1 invokes T2: ({{template "T2"}}){{end}}`},
+		// T2.tmpl defines a template T2.
+		{"T2.tmpl", `{{define "T2"}}This is T2{{end}}`},
+	})
+	// Clean up after the test; another quirk of running as an example.
+	defer os.RemoveAll(dir)
+
+	// pattern is the glob pattern used to find all the template files.
+	pattern := filepath.Join(dir, "*.tmpl")
+
+	// Here starts the example proper.
+	// T0.tmpl is the first name matched, so it becomes the starting template,
+	// the value returned by ParseGlob.
+	tmpl := template.Must(template.ParseGlob(pattern))
+
+	err := tmpl.Execute(os.Stdout, nil)
+	if err != nil {
+		log.Fatalf("template execution: %s", err)
+	}
+	// Output:
+	// T0 invokes T1: (T1 invokes T2: (This is T2))
+}
+
+// Here we demonstrate loading a set of templates from files in different directories
+func ExampleTemplate_parsefiles() {
+	// Here we create different temporary directories and populate them with our sample
+	// template definition files; usually the template files would already
+	// exist in some location known to the program.
+	dir1 := createTestDir([]templateFile{
+		// T1.tmpl is a plain template file that just invokes T2.
+		{"T1.tmpl", `T1 invokes T2: ({{template "T2"}})`},
+	})
+
+	dir2 := createTestDir([]templateFile{
+		// T2.tmpl defines a template T2.
+		{"T2.tmpl", `{{define "T2"}}This is T2{{end}}`},
+	})
+
+	// Clean up after the test; another quirk of running as an example.
+	defer func(dirs ...string) {
+		for _, dir := range dirs {
+			os.RemoveAll(dir)
+		}
+	}(dir1, dir2)
+
+	// Here starts the example proper.
+	// Let's just parse only dir1/T0 and dir2/T2
+	paths := []string{
+		filepath.Join(dir1, "T1.tmpl"),
+		filepath.Join(dir2, "T2.tmpl"),
+	}
+	tmpl := template.Must(template.ParseFiles(paths...))
+
+	err := tmpl.Execute(os.Stdout, nil)
+	if err != nil {
+		log.Fatalf("template execution: %s", err)
+	}
+	// Output:
+	// T1 invokes T2: (This is T2)
+}
+
+// The following example is duplicated in text/template; keep them in sync.
+
+// This example demonstrates one way to share some templates
+// and use them in different contexts. In this variant we add multiple driver
+// templates by hand to an existing bundle of templates.
+func ExampleTemplate_helpers() {
+	// Here we create a temporary directory and populate it with our sample
+	// template definition files; usually the template files would already
+	// exist in some location known to the program.
+	dir := createTestDir([]templateFile{
+		// T1.tmpl defines a template, T1 that invokes T2.
+		{"T1.tmpl", `{{define "T1"}}T1 invokes T2: ({{template "T2"}}){{end}}`},
+		// T2.tmpl defines a template T2.
+		{"T2.tmpl", `{{define "T2"}}This is T2{{end}}`},
+	})
+	// Clean up after the test; another quirk of running as an example.
+	defer os.RemoveAll(dir)
+
+	// pattern is the glob pattern used to find all the template files.
+	pattern := filepath.Join(dir, "*.tmpl")
+
+	// Here starts the example proper.
+	// Load the helpers.
+	templates := template.Must(template.ParseGlob(pattern))
+	// Add one driver template to the bunch; we do this with an explicit template definition.
+	_, err := templates.Parse("{{define `driver1`}}Driver 1 calls T1: ({{template `T1`}})\n{{end}}")
+	if err != nil {
+		log.Fatal("parsing driver1: ", err)
+	}
+	// Add another driver template.
+	_, err = templates.Parse("{{define `driver2`}}Driver 2 calls T2: ({{template `T2`}})\n{{end}}")
+	if err != nil {
+		log.Fatal("parsing driver2: ", err)
+	}
+	// We load all the templates before execution. This package does not require
+	// that behavior but html/template's escaping does, so it's a good habit.
+	err = templates.ExecuteTemplate(os.Stdout, "driver1", nil)
+	if err != nil {
+		log.Fatalf("driver1 execution: %s", err)
+	}
+	err = templates.ExecuteTemplate(os.Stdout, "driver2", nil)
+	if err != nil {
+		log.Fatalf("driver2 execution: %s", err)
+	}
+	// Output:
+	// Driver 1 calls T1: (T1 invokes T2: (This is T2))
+	// Driver 2 calls T2: (This is T2)
+}
+
+// The following example is duplicated in text/template; keep them in sync.
+
+// This example demonstrates how to use one group of driver
+// templates with distinct sets of helper templates.
+func ExampleTemplate_share() {
+	// Here we create a temporary directory and populate it with our sample
+	// template definition files; usually the template files would already
+	// exist in some location known to the program.
+	dir := createTestDir([]templateFile{
+		// T0.tmpl is a plain template file that just invokes T1.
+		{"T0.tmpl", "T0 ({{.}} version) invokes T1: ({{template `T1`}})\n"},
+		// T1.tmpl defines a template, T1 that invokes T2. Note T2 is not defined
+		{"T1.tmpl", `{{define "T1"}}T1 invokes T2: ({{template "T2"}}){{end}}`},
+	})
+	// Clean up after the test; another quirk of running as an example.
+	defer os.RemoveAll(dir)
+
+	// pattern is the glob pattern used to find all the template files.
+	pattern := filepath.Join(dir, "*.tmpl")
+
+	// Here starts the example proper.
+	// Load the drivers.
+	drivers := template.Must(template.ParseGlob(pattern))
+
+	// We must define an implementation of the T2 template. First we clone
+	// the drivers, then add a definition of T2 to the template name space.
+
+	// 1. Clone the helper set to create a new name space from which to run them.
+	first, err := drivers.Clone()
+	if err != nil {
+		log.Fatal("cloning helpers: ", err)
+	}
+	// 2. Define T2, version A, and parse it.
+	_, err = first.Parse("{{define `T2`}}T2, version A{{end}}")
+	if err != nil {
+		log.Fatal("parsing T2: ", err)
+	}
+
+	// Now repeat the whole thing, using a different version of T2.
+	// 1. Clone the drivers.
+	second, err := drivers.Clone()
+	if err != nil {
+		log.Fatal("cloning drivers: ", err)
+	}
+	// 2. Define T2, version B, and parse it.
+	_, err = second.Parse("{{define `T2`}}T2, version B{{end}}")
+	if err != nil {
+		log.Fatal("parsing T2: ", err)
+	}
+
+	// Execute the templates in the reverse order to verify the
+	// first is unaffected by the second.
+	err = second.ExecuteTemplate(os.Stdout, "T0.tmpl", "second")
+	if err != nil {
+		log.Fatalf("second execution: %s", err)
+	}
+	err = first.ExecuteTemplate(os.Stdout, "T0.tmpl", "first")
+	if err != nil {
+		log.Fatalf("first: execution: %s", err)
+	}
+
+	// Output:
+	// T0 (second version) invokes T1: (T1 invokes T2: (T2, version B))
+	// T0 (first version) invokes T1: (T1 invokes T2: (T2, version A))
+}
diff --git a/libgo/go/html/template/template.go b/libgo/go/html/template/template.go
index 96ab268a7f4..063e46d6bf3 100644
--- a/libgo/go/html/template/template.go
+++ b/libgo/go/html/template/template.go
@@ -346,6 +346,11 @@ func Must(t *Template, err error) *Template {
 // the named files. The returned template's name will have the (base) name and
 // (parsed) contents of the first file. There must be at least one file.
 // If an error occurs, parsing stops and the returned *Template is nil.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+// For instance, ParseFiles("a/foo", "b/foo") stores "b/foo" as the template
+// named "foo", while "a/foo" is unavailable.
 func ParseFiles(filenames ...string) (*Template, error) {
 	return parseFiles(nil, filenames...)
 }
@@ -353,6 +358,9 @@ func ParseFiles(filenames ...string) (*Template, error) {
 // ParseFiles parses the named files and associates the resulting templates with
 // t. If an error occurs, parsing stops and the returned template is nil;
 // otherwise it is t. There must be at least one file.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
 func (t *Template) ParseFiles(filenames ...string) (*Template, error) {
 	return parseFiles(t, filenames...)
 }
@@ -399,6 +407,9 @@ func parseFiles(t *Template, filenames ...string) (*Template, error) {
 // returned template will have the (base) name and (parsed) contents of the
 // first file matched by the pattern. ParseGlob is equivalent to calling
 // ParseFiles with the list of files matched by the pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
 func ParseGlob(pattern string) (*Template, error) {
 	return parseGlob(nil, pattern)
 }
@@ -408,6 +419,9 @@ func ParseGlob(pattern string) (*Template, error) {
 // processed by filepath.Glob and must match at least one file. ParseGlob is
 // equivalent to calling t.ParseFiles with the list of files matched by the
 // pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
 func (t *Template) ParseGlob(pattern string) (*Template, error) {
 	return parseGlob(t, pattern)
 }
diff --git a/libgo/go/html/template/template_test.go b/libgo/go/html/template/template_test.go
index 6f70d67de92..46df1f8d495 100644
--- a/libgo/go/html/template/template_test.go
+++ b/libgo/go/html/template/template_test.go
@@ -13,7 +13,7 @@ func TestTemplateClone(t *testing.T) {
 		t.Fatal(err)
 	}
 	if len(clone.Templates()) != len(orig.Templates()) {
-		t.Fatalf("Invalid lenth of t.Clone().Templates()")
+		t.Fatalf("Invalid length of t.Clone().Templates()")
 	}
 
 	const want = "stuff"
diff --git a/libgo/go/html/template/url.go b/libgo/go/html/template/url.go
index 2ca76bf389f..246bfd32cd5 100644
--- a/libgo/go/html/template/url.go
+++ b/libgo/go/html/template/url.go
@@ -17,7 +17,7 @@ func urlFilter(args ...interface{}) string {
 	if t == contentTypeURL {
 		return s
 	}
-	if i := strings.IndexRune(s, ':'); i >= 0 && strings.IndexRune(s[:i], '/') < 0 {
+	if i := strings.IndexRune(s, ':'); i >= 0 && !strings.ContainsRune(s[:i], '/') {
 		protocol := strings.ToLower(s[:i])
 		if protocol != "http" && protocol != "https" && protocol != "mailto" {
 			return "#" + filterFailsafe
diff --git a/libgo/go/image/color/color.go b/libgo/go/image/color/color.go
index cae059b6daa..104433974ea 100644
--- a/libgo/go/image/color/color.go
+++ b/libgo/go/image/color/color.go
@@ -147,7 +147,7 @@ type Model interface {
 func ModelFunc(f func(Color) Color) Model {
 	// Note: using *modelFunc as the implementation
 	// means that callers can still use comparisons
-	// like m == RGBAModel.  This is not possible if
+	// like m == RGBAModel. This is not possible if
 	// we use the func value directly, because funcs
 	// are no longer comparable.
 	return &modelFunc{f}
diff --git a/libgo/go/image/color/palette/gen.go b/libgo/go/image/color/palette/gen.go
index 2b5fdaaf2b3..57718e6a0c5 100644
--- a/libgo/go/image/color/palette/gen.go
+++ b/libgo/go/image/color/palette/gen.go
@@ -89,7 +89,7 @@ func printPlan9(w io.Writer) {
 	fmt.Fprintln(w, "// of continuous tones.")
 	fmt.Fprintln(w, "//")
 	fmt.Fprintln(w, "// This palette was used in the Plan 9 Operating System, described at")
-	fmt.Fprintln(w, "// http://plan9.bell-labs.com/magic/man2html/6/color")
+	fmt.Fprintln(w, "// https://9p.io/magic/man2html/6/color")
 	fmt.Fprintln(w, "var Plan9 = []color.Color{")
 	for _, line := range lines {
 		fmt.Fprintln(w, line)
diff --git a/libgo/go/image/color/palette/palette.go b/libgo/go/image/color/palette/palette.go
index 0bf2c8e1aa5..b6954145204 100644
--- a/libgo/go/image/color/palette/palette.go
+++ b/libgo/go/image/color/palette/palette.go
@@ -19,7 +19,7 @@ import "image/color"
 // of continuous tones.
 //
 // This palette was used in the Plan 9 Operating System, described at
-// http://plan9.bell-labs.com/magic/man2html/6/color
+// https://9p.io/magic/man2html/6/color
 var Plan9 = []color.Color{
 	color.RGBA{0x00, 0x00, 0x00, 0xff},
 	color.RGBA{0x00, 0x00, 0x44, 0xff},
diff --git a/libgo/go/image/color/ycbcr.go b/libgo/go/image/color/ycbcr.go
index 904434f6a3d..3df5d3675d6 100644
--- a/libgo/go/image/color/ycbcr.go
+++ b/libgo/go/image/color/ycbcr.go
@@ -15,24 +15,37 @@ func RGBToYCbCr(r, g, b uint8) (uint8, uint8, uint8) {
 	r1 := int32(r)
 	g1 := int32(g)
 	b1 := int32(b)
+
+	// yy is in range [0,0xff].
 	yy := (19595*r1 + 38470*g1 + 7471*b1 + 1<<15) >> 16
-	cb := (-11056*r1 - 21712*g1 + 32768*b1 + 257<<15) >> 16
-	cr := (32768*r1 - 27440*g1 - 5328*b1 + 257<<15) >> 16
-	if yy < 0 {
-		yy = 0
-	} else if yy > 0xff {
-		yy = 0xff
-	}
-	if cb < 0 {
-		cb = 0
-	} else if cb > 0xff {
-		cb = 0xff
+
+	// The bit twiddling below is equivalent to
+	//
+	// cb := (-11056*r1 - 21712*g1 + 32768*b1 + 257<<15) >> 16
+	// if cb < 0 {
+	//     cb = 0
+	// } else if cb > 0xff {
+	//     cb = ^int32(0)
+	// }
+	//
+	// but uses fewer branches and is faster.
+	// Note that the uint8 type conversion in the return
+	// statement will convert ^int32(0) to 0xff.
+	// The code below to compute cr uses a similar pattern.
+	cb := -11056*r1 - 21712*g1 + 32768*b1 + 257<<15
+	if uint32(cb)&0xff000000 == 0 {
+		cb >>= 16
+	} else {
+		cb = ^(cb >> 31)
 	}
-	if cr < 0 {
-		cr = 0
-	} else if cr > 0xff {
-		cr = 0xff
+
+	cr := 32768*r1 - 27440*g1 - 5328*b1 + 257<<15
+	if uint32(cr)&0xff000000 == 0 {
+		cr >>= 16
+	} else {
+		cr = ^(cr >> 31)
 	}
+
 	return uint8(yy), uint8(cb), uint8(cr)
 }
 
@@ -44,27 +57,44 @@ func YCbCrToRGB(y, cb, cr uint8) (uint8, uint8, uint8) {
 	//	B = Y' + 1.77200*(Cb-128)
 	// http://www.w3.org/Graphics/JPEG/jfif3.pdf says Y but means Y'.
 
-	yy1 := int32(y) * 0x10100 // Convert 0x12 to 0x121200.
+	yy1 := int32(y) * 0x010100 // Convert 0x12 to 0x121200.
 	cb1 := int32(cb) - 128
 	cr1 := int32(cr) - 128
-	r := (yy1 + 91881*cr1) >> 16
-	g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
-	b := (yy1 + 116130*cb1) >> 16
-	if r < 0 {
-		r = 0
-	} else if r > 0xff {
-		r = 0xff
+
+	// The bit twiddling below is equivalent to
+	//
+	// r := (yy1 + 91881*cr1) >> 16
+	// if r < 0 {
+	//     r = 0
+	// } else if r > 0xff {
+	//     r = ^int32(0)
+	// }
+	//
+	// but uses fewer branches and is faster.
+	// Note that the uint8 type conversion in the return
+	// statement will convert ^int32(0) to 0xff.
+	// The code below to compute g and b uses a similar pattern.
+	r := yy1 + 91881*cr1
+	if uint32(r)&0xff000000 == 0 {
+		r >>= 16
+	} else {
+		r = ^(r >> 31)
 	}
-	if g < 0 {
-		g = 0
-	} else if g > 0xff {
-		g = 0xff
+
+	g := yy1 - 22554*cb1 - 46802*cr1
+	if uint32(g)&0xff000000 == 0 {
+		g >>= 16
+	} else {
+		g = ^(g >> 31)
 	}
-	if b < 0 {
-		b = 0
-	} else if b > 0xff {
-		b = 0xff
+
+	b := yy1 + 116130*cb1
+	if uint32(b)&0xff000000 == 0 {
+		b >>= 16
+	} else {
+		b = ^(b >> 31)
 	}
+
 	return uint8(r), uint8(g), uint8(b)
 }
 
@@ -220,10 +250,10 @@ func RGBToCMYK(r, g, b uint8) (uint8, uint8, uint8, uint8) {
 
 // CMYKToRGB converts a CMYK quadruple to an RGB triple.
 func CMYKToRGB(c, m, y, k uint8) (uint8, uint8, uint8) {
-	w := uint32(0xffff - uint32(k)*0x101)
-	r := uint32(0xffff-uint32(c)*0x101) * w / 0xffff
-	g := uint32(0xffff-uint32(m)*0x101) * w / 0xffff
-	b := uint32(0xffff-uint32(y)*0x101) * w / 0xffff
+	w := 0xffff - uint32(k)*0x101
+	r := (0xffff - uint32(c)*0x101) * w / 0xffff
+	g := (0xffff - uint32(m)*0x101) * w / 0xffff
+	b := (0xffff - uint32(y)*0x101) * w / 0xffff
 	return uint8(r >> 8), uint8(g >> 8), uint8(b >> 8)
 }
 
@@ -239,11 +269,11 @@ func (c CMYK) RGBA() (uint32, uint32, uint32, uint32) {
 	// This code is a copy of the CMYKToRGB function above, except that it
 	// returns values in the range [0, 0xffff] instead of [0, 0xff].
 
-	w := uint32(0xffff - uint32(c.K)*0x101)
-	r := uint32(0xffff-uint32(c.C)*0x101) * w / 0xffff
-	g := uint32(0xffff-uint32(c.M)*0x101) * w / 0xffff
-	b := uint32(0xffff-uint32(c.Y)*0x101) * w / 0xffff
-	return uint32(r), uint32(g), uint32(b), 0xffff
+	w := 0xffff - uint32(c.K)*0x101
+	r := (0xffff - uint32(c.C)*0x101) * w / 0xffff
+	g := (0xffff - uint32(c.M)*0x101) * w / 0xffff
+	b := (0xffff - uint32(c.Y)*0x101) * w / 0xffff
+	return r, g, b, 0xffff
 }
 
 // CMYKModel is the Model for CMYK colors.
diff --git a/libgo/go/image/color/ycbcr_test.go b/libgo/go/image/color/ycbcr_test.go
index f5e7cbf3358..561699f4e0e 100644
--- a/libgo/go/image/color/ycbcr_test.go
+++ b/libgo/go/image/color/ycbcr_test.go
@@ -171,3 +171,47 @@ func TestPalette(t *testing.T) {
 		t.Errorf("got %v, want %v", got, want)
 	}
 }
+
+var sink uint8
+
+func BenchmarkYCbCrToRGB(b *testing.B) {
+	// YCbCrToRGB does saturating arithmetic.
+	// Low, middle, and high values can take
+	// different paths through the generated code.
+	b.Run("0", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			sink, sink, sink = YCbCrToRGB(0, 0, 0)
+		}
+	})
+	b.Run("128", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			sink, sink, sink = YCbCrToRGB(128, 128, 128)
+		}
+	})
+	b.Run("255", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			sink, sink, sink = YCbCrToRGB(255, 255, 255)
+		}
+	})
+}
+
+func BenchmarkRGBToYCbCr(b *testing.B) {
+	// RGBToYCbCr does saturating arithmetic.
+	// Different values can take different paths
+	// through the generated code.
+	b.Run("0", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			sink, sink, sink = RGBToYCbCr(0, 0, 0)
+		}
+	})
+	b.Run("Cb", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			sink, sink, sink = RGBToYCbCr(0, 0, 255)
+		}
+	})
+	b.Run("Cr", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			sink, sink, sink = RGBToYCbCr(255, 0, 0)
+		}
+	})
+}
diff --git a/libgo/go/image/decode_test.go b/libgo/go/image/decode_test.go
index d16ef8a1a4d..85e235e729b 100644
--- a/libgo/go/image/decode_test.go
+++ b/libgo/go/image/decode_test.go
@@ -36,6 +36,7 @@ var imageTests = []imageTest{
 	{"testdata/video-001.221212.png", "testdata/video-001.221212.jpeg", 8 << 8},
 	{"testdata/video-001.cmyk.png", "testdata/video-001.cmyk.jpeg", 8 << 8},
 	{"testdata/video-001.rgb.png", "testdata/video-001.rgb.jpeg", 8 << 8},
+	{"testdata/video-001.progressive.truncated.png", "testdata/video-001.progressive.truncated.jpeg", 8 << 8},
 	// Grayscale images.
 	{"testdata/video-005.gray.png", "testdata/video-005.gray.jpeg", 8 << 8},
 	{"testdata/video-005.gray.png", "testdata/video-005.gray.png", 0},
diff --git a/libgo/go/image/draw/draw.go b/libgo/go/image/draw/draw.go
index e47c48d961e..6a16cd39cf8 100644
--- a/libgo/go/image/draw/draw.go
+++ b/libgo/go/image/draw/draw.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -634,10 +634,10 @@ func drawPaletted(dst Image, r image.Rectangle, src image.Image, sp image.Point,
 				if !floydSteinberg {
 					continue
 				}
-				er -= int32(palette[bestIndex][0])
-				eg -= int32(palette[bestIndex][1])
-				eb -= int32(palette[bestIndex][2])
-				ea -= int32(palette[bestIndex][3])
+				er -= palette[bestIndex][0]
+				eg -= palette[bestIndex][1]
+				eb -= palette[bestIndex][2]
+				ea -= palette[bestIndex][3]
 
 			} else {
 				out.R = uint16(er)
diff --git a/libgo/go/image/gif/reader.go b/libgo/go/image/gif/reader.go
index 6a133124ad5..6181a946fad 100644
--- a/libgo/go/image/gif/reader.go
+++ b/libgo/go/image/gif/reader.go
@@ -96,7 +96,7 @@ type decoder struct {
 // blockReader parses the block structure of GIF image data, which
 // comprises (n, (n bytes)) blocks, with 1 <= n <= 255.  It is the
 // reader given to the LZW decoder, which is thus immune to the
-// blocking.  After the LZW decoder completes, there will be a 0-byte
+// blocking. After the LZW decoder completes, there will be a 0-byte
 // block remaining (0, ()), which is consumed when checking that the
 // blockReader is exhausted.
 type blockReader struct {
@@ -178,12 +178,25 @@ func (d *decoder) decode(r io.Reader, configOnly bool) error {
 				}
 				m.Palette = d.globalColorTable
 			}
-			if d.hasTransparentIndex && int(d.transparentIndex) < len(m.Palette) {
+			if d.hasTransparentIndex {
 				if !useLocalColorTable {
 					// Clone the global color table.
 					m.Palette = append(color.Palette(nil), d.globalColorTable...)
 				}
-				m.Palette[d.transparentIndex] = color.RGBA{}
+				if ti := int(d.transparentIndex); ti < len(m.Palette) {
+					m.Palette[ti] = color.RGBA{}
+				} else {
+					// The transparentIndex is out of range, which is an error
+					// according to the spec, but Firefox and Google Chrome
+					// seem OK with this, so we enlarge the palette with
+					// transparent colors. See golang.org/issue/15059.
+					p := make(color.Palette, ti+1)
+					copy(p, m.Palette)
+					for i := len(m.Palette); i < len(p); i++ {
+						p[i] = color.RGBA{}
+					}
+					m.Palette = p
+				}
 			}
 			litWidth, err := d.r.ReadByte()
 			if err != nil {
@@ -210,7 +223,7 @@ func (d *decoder) decode(r io.Reader, configOnly bool) error {
 			// for an image". In practice, though, giflib (a widely used C
 			// library) does not enforce this, so we also accept lzwr returning
 			// io.ErrUnexpectedEOF (meaning that the encoded stream hit io.EOF
-			// before the LZW decoder saw an explict end code), provided that
+			// before the LZW decoder saw an explicit end code), provided that
 			// the io.ReadFull call above successfully read len(m.Pix) bytes.
 			// See https://golang.org/issue/9856 for an example GIF.
 			if n, err := lzwr.Read(d.tmp[:1]); n != 0 || (err != io.EOF && err != io.ErrUnexpectedEOF) {
@@ -349,6 +362,9 @@ func (d *decoder) readGraphicControl() error {
 	if _, err := io.ReadFull(d.r, d.tmp[:6]); err != nil {
 		return fmt.Errorf("gif: can't read graphic control: %s", err)
 	}
+	if d.tmp[0] != 4 {
+		return fmt.Errorf("gif: invalid graphic control extension block size: %d", d.tmp[0])
+	}
 	flags := d.tmp[1]
 	d.disposalMethod = (flags & gcDisposalMethodMask) >> 2
 	d.delayTime = int(d.tmp[2]) | int(d.tmp[3])<<8
@@ -356,6 +372,9 @@ func (d *decoder) readGraphicControl() error {
 		d.transparentIndex = d.tmp[4]
 		d.hasTransparentIndex = true
 	}
+	if d.tmp[5] != 0 {
+		return fmt.Errorf("gif: invalid graphic control extension block terminator: %d", d.tmp[5])
+	}
 	return nil
 }
 
diff --git a/libgo/go/image/gif/reader_test.go b/libgo/go/image/gif/reader_test.go
index c294195b6f7..90c81493cba 100644
--- a/libgo/go/image/gif/reader_test.go
+++ b/libgo/go/image/gif/reader_test.go
@@ -22,12 +22,16 @@ const (
 	trailerStr = "\x3b"
 )
 
-// lzwEncode returns an LZW encoding (with 2-bit literals) of n zeroes.
-func lzwEncode(n int) []byte {
+// lzwEncode returns an LZW encoding (with 2-bit literals) of in.
+func lzwEncode(in []byte) []byte {
 	b := &bytes.Buffer{}
 	w := lzw.NewWriter(b, lzw.LSB, 2)
-	w.Write(make([]byte, n))
-	w.Close()
+	if _, err := w.Write(in); err != nil {
+		panic(err)
+	}
+	if err := w.Close(); err != nil {
+		panic(err)
+	}
 	return b.Bytes()
 }
 
@@ -53,7 +57,7 @@ func TestDecode(t *testing.T) {
 		// byte, and 2-bit LZW literals.
 		b.WriteString("\x2c\x00\x00\x00\x00\x02\x00\x01\x00\x00\x02")
 		if tc.nPix > 0 {
-			enc := lzwEncode(tc.nPix)
+			enc := lzwEncode(make([]byte, tc.nPix))
 			if len(enc) > 0xff {
 				t.Errorf("nPix=%d, extra=%t: compressed length %d is too large", tc.nPix, tc.extra, len(enc))
 				continue
@@ -97,13 +101,13 @@ func TestTransparentIndex(t *testing.T) {
 	for transparentIndex := 0; transparentIndex < 3; transparentIndex++ {
 		if transparentIndex < 2 {
 			// Write the graphic control for the transparent index.
-			b.WriteString("\x21\xf9\x00\x01\x00\x00")
+			b.WriteString("\x21\xf9\x04\x01\x00\x00")
 			b.WriteByte(byte(transparentIndex))
 			b.WriteByte(0)
 		}
 		// Write an image with bounds 2x1, as per TestDecode.
 		b.WriteString("\x2c\x00\x00\x00\x00\x02\x00\x01\x00\x00\x02")
-		enc := lzwEncode(2)
+		enc := lzwEncode([]byte{0x00, 0x00})
 		if len(enc) > 0xff {
 			t.Fatalf("compressed length %d is too large", len(enc))
 		}
@@ -196,21 +200,13 @@ func TestNoPalette(t *testing.T) {
 	b.WriteString(headerStr[:len(headerStr)-3])
 	b.WriteString("\x00\x00\x00") // No global palette.
 
-	// Image descriptor: 2x1, no local palette.
+	// Image descriptor: 2x1, no local palette, and 2-bit LZW literals.
 	b.WriteString("\x2c\x00\x00\x00\x00\x02\x00\x01\x00\x00\x02")
 
 	// Encode the pixels: neither is in range, because there is no palette.
-	pix := []byte{0, 3}
-	enc := &bytes.Buffer{}
-	w := lzw.NewWriter(enc, lzw.LSB, 2)
-	if _, err := w.Write(pix); err != nil {
-		t.Fatalf("Write: %v", err)
-	}
-	if err := w.Close(); err != nil {
-		t.Fatalf("Close: %v", err)
-	}
-	b.WriteByte(byte(len(enc.Bytes())))
-	b.Write(enc.Bytes())
+	enc := lzwEncode([]byte{0x00, 0x03})
+	b.WriteByte(byte(len(enc)))
+	b.Write(enc)
 	b.WriteByte(0x00) // An empty block signifies the end of the image data.
 
 	b.WriteString(trailerStr)
@@ -226,21 +222,13 @@ func TestPixelOutsidePaletteRange(t *testing.T) {
 		b.WriteString(headerStr)
 		b.WriteString(paletteStr)
 
-		// Image descriptor: 2x1, no local palette.
+		// Image descriptor: 2x1, no local palette, and 2-bit LZW literals.
 		b.WriteString("\x2c\x00\x00\x00\x00\x02\x00\x01\x00\x00\x02")
 
 		// Encode the pixels; some pvals trigger the expected error.
-		pix := []byte{pval, pval}
-		enc := &bytes.Buffer{}
-		w := lzw.NewWriter(enc, lzw.LSB, 2)
-		if _, err := w.Write(pix); err != nil {
-			t.Fatalf("Write: %v", err)
-		}
-		if err := w.Close(); err != nil {
-			t.Fatalf("Close: %v", err)
-		}
-		b.WriteByte(byte(len(enc.Bytes())))
-		b.Write(enc.Bytes())
+		enc := lzwEncode([]byte{pval, pval})
+		b.WriteByte(byte(len(enc)))
+		b.Write(enc)
 		b.WriteByte(0x00) // An empty block signifies the end of the image data.
 
 		b.WriteString(trailerStr)
@@ -254,6 +242,36 @@ func TestPixelOutsidePaletteRange(t *testing.T) {
 	}
 }
 
+func TestTransparentPixelOutsidePaletteRange(t *testing.T) {
+	b := &bytes.Buffer{}
+
+	// Manufacture a GIF with a 2 color palette.
+	b.WriteString(headerStr)
+	b.WriteString(paletteStr)
+
+	// Graphic Control Extension: transparency, transparent color index = 3.
+	//
+	// This index, 3, is out of range of the global palette and there is no
+	// local palette in the subsequent image descriptor. This is an error
+	// according to the spec, but Firefox and Google Chrome seem OK with this.
+	//
+	// See golang.org/issue/15059.
+	b.WriteString("\x21\xf9\x04\x01\x00\x00\x03\x00")
+
+	// Image descriptor: 2x1, no local palette, and 2-bit LZW literals.
+	b.WriteString("\x2c\x00\x00\x00\x00\x02\x00\x01\x00\x00\x02")
+
+	// Encode the pixels.
+	enc := lzwEncode([]byte{0x03, 0x03})
+	b.WriteByte(byte(len(enc)))
+	b.Write(enc)
+	b.WriteByte(0x00) // An empty block signifies the end of the image data.
+
+	b.WriteString(trailerStr)
+
+	try(t, b.Bytes(), "")
+}
+
 func TestLoopCount(t *testing.T) {
 	data := []byte("GIF89a000\x00000,0\x00\x00\x00\n\x00" +
 		"\n\x00\x80000000\x02\b\xf01u\xb9\xfdal\x05\x00;")
diff --git a/libgo/go/image/internal/imageutil/gen.go b/libgo/go/image/internal/imageutil/gen.go
index fc1e707f0fd..6792b28a45b 100644
--- a/libgo/go/image/internal/imageutil/gen.go
+++ b/libgo/go/image/internal/imageutil/gen.go
@@ -95,32 +95,51 @@ const sratioCase = `
 			%s
 
 				// This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
-				yy1 := int32(src.Y[yi]) * 0x10100 // Convert 0x12 to 0x121200.
+				yy1 := int32(src.Y[yi]) * 0x010100 // Convert 0x12 to 0x121200.
 				cb1 := int32(src.Cb[ci]) - 128
 				cr1 := int32(src.Cr[ci]) - 128
-				r := (yy1 + 91881*cr1) >> 16
-				g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
-				b := (yy1 + 116130*cb1) >> 16
-				if r < 0 {
-					r = 0
-				} else if r > 255 {
-					r = 255
+
+				// The bit twiddling below is equivalent to
+				//
+				// r := (yy1 + 91881*cr1) >> 16
+				// if r < 0 {
+				//     r = 0
+				// } else if r > 0xff {
+				//     r = ^int32(0)
+				// }
+				//
+				// but uses fewer branches and is faster.
+				// Note that the uint8 type conversion in the return
+				// statement will convert ^int32(0) to 0xff.
+				// The code below to compute g and b uses a similar pattern.
+				r := yy1 + 91881*cr1
+				if uint32(r)&0xff000000 == 0 {
+					r >>= 16
+				} else {
+					r = ^(r >> 31)
 				}
-				if g < 0 {
-					g = 0
-				} else if g > 255 {
-					g = 255
+
+				g := yy1 - 22554*cb1 - 46802*cr1
+				if uint32(g)&0xff000000 == 0 {
+					g >>= 16
+				} else {
+					g = ^(g >> 31)
 				}
-				if b < 0 {
-					b = 0
-				} else if b > 255 {
-					b = 255
+
+				b := yy1 + 116130*cb1
+				if uint32(b)&0xff000000 == 0 {
+					b >>= 16
+				} else {
+					b = ^(b >> 31)
 				}
 
-				dpix[x+0] = uint8(r)
-				dpix[x+1] = uint8(g)
-				dpix[x+2] = uint8(b)
-				dpix[x+3] = 255
+
+				// use a temp slice to hint to the compiler that a single bounds check suffices
+				rgba := dpix[x : x+4 : len(dpix)]
+				rgba[0] = uint8(r)
+				rgba[1] = uint8(g)
+				rgba[2] = uint8(b)
+				rgba[3] = 255
 			}
 		}
 `
diff --git a/libgo/go/image/internal/imageutil/impl.go b/libgo/go/image/internal/imageutil/impl.go
index fd7826d4a97..3696b08e419 100644
--- a/libgo/go/image/internal/imageutil/impl.go
+++ b/libgo/go/image/internal/imageutil/impl.go
@@ -44,32 +44,50 @@ func DrawYCbCr(dst *image.RGBA, r image.Rectangle, src *image.YCbCr, sp image.Po
 			for x := x0; x != x1; x, yi, ci = x+4, yi+1, ci+1 {
 
 				// This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
-				yy1 := int32(src.Y[yi]) * 0x10100 // Convert 0x12 to 0x121200.
+				yy1 := int32(src.Y[yi]) * 0x010100 // Convert 0x12 to 0x121200.
 				cb1 := int32(src.Cb[ci]) - 128
 				cr1 := int32(src.Cr[ci]) - 128
-				r := (yy1 + 91881*cr1) >> 16
-				g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
-				b := (yy1 + 116130*cb1) >> 16
-				if r < 0 {
-					r = 0
-				} else if r > 255 {
-					r = 255
+
+				// The bit twiddling below is equivalent to
+				//
+				// r := (yy1 + 91881*cr1) >> 16
+				// if r < 0 {
+				//     r = 0
+				// } else if r > 0xff {
+				//     r = ^int32(0)
+				// }
+				//
+				// but uses fewer branches and is faster.
+				// Note that the uint8 type conversion in the return
+				// statement will convert ^int32(0) to 0xff.
+				// The code below to compute g and b uses a similar pattern.
+				r := yy1 + 91881*cr1
+				if uint32(r)&0xff000000 == 0 {
+					r >>= 16
+				} else {
+					r = ^(r >> 31)
 				}
-				if g < 0 {
-					g = 0
-				} else if g > 255 {
-					g = 255
+
+				g := yy1 - 22554*cb1 - 46802*cr1
+				if uint32(g)&0xff000000 == 0 {
+					g >>= 16
+				} else {
+					g = ^(g >> 31)
 				}
-				if b < 0 {
-					b = 0
-				} else if b > 255 {
-					b = 255
+
+				b := yy1 + 116130*cb1
+				if uint32(b)&0xff000000 == 0 {
+					b >>= 16
+				} else {
+					b = ^(b >> 31)
 				}
 
-				dpix[x+0] = uint8(r)
-				dpix[x+1] = uint8(g)
-				dpix[x+2] = uint8(b)
-				dpix[x+3] = 255
+				// use a temp slice to hint to the compiler that a single bounds check suffices
+				rgba := dpix[x : x+4 : len(dpix)]
+				rgba[0] = uint8(r)
+				rgba[1] = uint8(g)
+				rgba[2] = uint8(b)
+				rgba[3] = 255
 			}
 		}
 
@@ -83,32 +101,50 @@ func DrawYCbCr(dst *image.RGBA, r image.Rectangle, src *image.YCbCr, sp image.Po
 				ci := ciBase + sx/2
 
 				// This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
-				yy1 := int32(src.Y[yi]) * 0x10100 // Convert 0x12 to 0x121200.
+				yy1 := int32(src.Y[yi]) * 0x010100 // Convert 0x12 to 0x121200.
 				cb1 := int32(src.Cb[ci]) - 128
 				cr1 := int32(src.Cr[ci]) - 128
-				r := (yy1 + 91881*cr1) >> 16
-				g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
-				b := (yy1 + 116130*cb1) >> 16
-				if r < 0 {
-					r = 0
-				} else if r > 255 {
-					r = 255
+
+				// The bit twiddling below is equivalent to
+				//
+				// r := (yy1 + 91881*cr1) >> 16
+				// if r < 0 {
+				//     r = 0
+				// } else if r > 0xff {
+				//     r = ^int32(0)
+				// }
+				//
+				// but uses fewer branches and is faster.
+				// Note that the uint8 type conversion in the return
+				// statement will convert ^int32(0) to 0xff.
+				// The code below to compute g and b uses a similar pattern.
+				r := yy1 + 91881*cr1
+				if uint32(r)&0xff000000 == 0 {
+					r >>= 16
+				} else {
+					r = ^(r >> 31)
 				}
-				if g < 0 {
-					g = 0
-				} else if g > 255 {
-					g = 255
+
+				g := yy1 - 22554*cb1 - 46802*cr1
+				if uint32(g)&0xff000000 == 0 {
+					g >>= 16
+				} else {
+					g = ^(g >> 31)
 				}
-				if b < 0 {
-					b = 0
-				} else if b > 255 {
-					b = 255
+
+				b := yy1 + 116130*cb1
+				if uint32(b)&0xff000000 == 0 {
+					b >>= 16
+				} else {
+					b = ^(b >> 31)
 				}
 
-				dpix[x+0] = uint8(r)
-				dpix[x+1] = uint8(g)
-				dpix[x+2] = uint8(b)
-				dpix[x+3] = 255
+				// use a temp slice to hint to the compiler that a single bounds check suffices
+				rgba := dpix[x : x+4 : len(dpix)]
+				rgba[0] = uint8(r)
+				rgba[1] = uint8(g)
+				rgba[2] = uint8(b)
+				rgba[3] = 255
 			}
 		}
 
@@ -122,32 +158,50 @@ func DrawYCbCr(dst *image.RGBA, r image.Rectangle, src *image.YCbCr, sp image.Po
 				ci := ciBase + sx/2
 
 				// This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
-				yy1 := int32(src.Y[yi]) * 0x10100 // Convert 0x12 to 0x121200.
+				yy1 := int32(src.Y[yi]) * 0x010100 // Convert 0x12 to 0x121200.
 				cb1 := int32(src.Cb[ci]) - 128
 				cr1 := int32(src.Cr[ci]) - 128
-				r := (yy1 + 91881*cr1) >> 16
-				g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
-				b := (yy1 + 116130*cb1) >> 16
-				if r < 0 {
-					r = 0
-				} else if r > 255 {
-					r = 255
+
+				// The bit twiddling below is equivalent to
+				//
+				// r := (yy1 + 91881*cr1) >> 16
+				// if r < 0 {
+				//     r = 0
+				// } else if r > 0xff {
+				//     r = ^int32(0)
+				// }
+				//
+				// but uses fewer branches and is faster.
+				// Note that the uint8 type conversion in the return
+				// statement will convert ^int32(0) to 0xff.
+				// The code below to compute g and b uses a similar pattern.
+				r := yy1 + 91881*cr1
+				if uint32(r)&0xff000000 == 0 {
+					r >>= 16
+				} else {
+					r = ^(r >> 31)
 				}
-				if g < 0 {
-					g = 0
-				} else if g > 255 {
-					g = 255
+
+				g := yy1 - 22554*cb1 - 46802*cr1
+				if uint32(g)&0xff000000 == 0 {
+					g >>= 16
+				} else {
+					g = ^(g >> 31)
 				}
-				if b < 0 {
-					b = 0
-				} else if b > 255 {
-					b = 255
+
+				b := yy1 + 116130*cb1
+				if uint32(b)&0xff000000 == 0 {
+					b >>= 16
+				} else {
+					b = ^(b >> 31)
 				}
 
-				dpix[x+0] = uint8(r)
-				dpix[x+1] = uint8(g)
-				dpix[x+2] = uint8(b)
-				dpix[x+3] = 255
+				// use a temp slice to hint to the compiler that a single bounds check suffices
+				rgba := dpix[x : x+4 : len(dpix)]
+				rgba[0] = uint8(r)
+				rgba[1] = uint8(g)
+				rgba[2] = uint8(b)
+				rgba[3] = 255
 			}
 		}
 
@@ -160,32 +214,50 @@ func DrawYCbCr(dst *image.RGBA, r image.Rectangle, src *image.YCbCr, sp image.Po
 			for x := x0; x != x1; x, yi, ci = x+4, yi+1, ci+1 {
 
 				// This is an inline version of image/color/ycbcr.go's func YCbCrToRGB.
-				yy1 := int32(src.Y[yi]) * 0x10100 // Convert 0x12 to 0x121200.
+				yy1 := int32(src.Y[yi]) * 0x010100 // Convert 0x12 to 0x121200.
 				cb1 := int32(src.Cb[ci]) - 128
 				cr1 := int32(src.Cr[ci]) - 128
-				r := (yy1 + 91881*cr1) >> 16
-				g := (yy1 - 22554*cb1 - 46802*cr1) >> 16
-				b := (yy1 + 116130*cb1) >> 16
-				if r < 0 {
-					r = 0
-				} else if r > 255 {
-					r = 255
+
+				// The bit twiddling below is equivalent to
+				//
+				// r := (yy1 + 91881*cr1) >> 16
+				// if r < 0 {
+				//     r = 0
+				// } else if r > 0xff {
+				//     r = ^int32(0)
+				// }
+				//
+				// but uses fewer branches and is faster.
+				// Note that the uint8 type conversion in the return
+				// statement will convert ^int32(0) to 0xff.
+				// The code below to compute g and b uses a similar pattern.
+				r := yy1 + 91881*cr1
+				if uint32(r)&0xff000000 == 0 {
+					r >>= 16
+				} else {
+					r = ^(r >> 31)
 				}
-				if g < 0 {
-					g = 0
-				} else if g > 255 {
-					g = 255
+
+				g := yy1 - 22554*cb1 - 46802*cr1
+				if uint32(g)&0xff000000 == 0 {
+					g >>= 16
+				} else {
+					g = ^(g >> 31)
 				}
-				if b < 0 {
-					b = 0
-				} else if b > 255 {
-					b = 255
+
+				b := yy1 + 116130*cb1
+				if uint32(b)&0xff000000 == 0 {
+					b >>= 16
+				} else {
+					b = ^(b >> 31)
 				}
 
-				dpix[x+0] = uint8(r)
-				dpix[x+1] = uint8(g)
-				dpix[x+2] = uint8(b)
-				dpix[x+3] = 255
+				// use a temp slice to hint to the compiler that a single bounds check suffices
+				rgba := dpix[x : x+4 : len(dpix)]
+				rgba[0] = uint8(r)
+				rgba[1] = uint8(g)
+				rgba[2] = uint8(b)
+				rgba[3] = 255
 			}
 		}
 
diff --git a/libgo/go/image/jpeg/reader.go b/libgo/go/image/jpeg/reader.go
index adf97abbd1d..c5834219a3e 100644
--- a/libgo/go/image/jpeg/reader.go
+++ b/libgo/go/image/jpeg/reader.go
@@ -641,6 +641,12 @@ func (d *decoder) decode(r io.Reader, configOnly bool) (image.Image, error) {
 			return nil, err
 		}
 	}
+
+	if d.progressive {
+		if err := d.reconstructProgressiveImage(); err != nil {
+			return nil, err
+		}
+	}
 	if d.img1 != nil {
 		return d.img1, nil
 	}
diff --git a/libgo/go/image/jpeg/scan.go b/libgo/go/image/jpeg/scan.go
index 99734c01af0..e1104d27c23 100644
--- a/libgo/go/image/jpeg/scan.go
+++ b/libgo/go/image/jpeg/scan.go
@@ -173,7 +173,6 @@ func (d *decoder) processSOS(n int) error {
 				compIndex := scan[i].compIndex
 				hi := d.comp[compIndex].h
 				vi := d.comp[compIndex].v
-				qt := &d.quant[d.comp[compIndex].tq]
 				for j := 0; j < hi*vi; j++ {
 					// The blocks are traversed one MCU at a time. For 4:2:0 chroma
 					// subsampling, there are four Y 8x8 blocks in every 16x16 MCU.
@@ -286,55 +285,19 @@ func (d *decoder) processSOS(n int) error {
 					}
 
 					if d.progressive {
-						if zigEnd != blockSize-1 || al != 0 {
-							// We haven't completely decoded this 8x8 block. Save the coefficients.
-							d.progCoeffs[compIndex][by*mxx*hi+bx] = b
-							// At this point, we could execute the rest of the loop body to dequantize and
-							// perform the inverse DCT, to save early stages of a progressive image to the
-							// *image.YCbCr buffers (the whole point of progressive encoding), but in Go,
-							// the jpeg.Decode function does not return until the entire image is decoded,
-							// so we "continue" here to avoid wasted computation.
-							continue
-						}
-					}
-
-					// Dequantize, perform the inverse DCT and store the block to the image.
-					for zig := 0; zig < blockSize; zig++ {
-						b[unzig[zig]] *= qt[zig]
+						// Save the coefficients.
+						d.progCoeffs[compIndex][by*mxx*hi+bx] = b
+						// At this point, we could call reconstructBlock to dequantize and perform the
+						// inverse DCT, to save early stages of a progressive image to the *image.YCbCr
+						// buffers (the whole point of progressive encoding), but in Go, the jpeg.Decode
+						// function does not return until the entire image is decoded, so we "continue"
+						// here to avoid wasted computation. Instead, reconstructBlock is called on each
+						// accumulated block by the reconstructProgressiveImage method after all of the
+						// SOS markers are processed.
+						continue
 					}
-					idct(&b)
-					dst, stride := []byte(nil), 0
-					if d.nComp == 1 {
-						dst, stride = d.img1.Pix[8*(by*d.img1.Stride+bx):], d.img1.Stride
-					} else {
-						switch compIndex {
-						case 0:
-							dst, stride = d.img3.Y[8*(by*d.img3.YStride+bx):], d.img3.YStride
-						case 1:
-							dst, stride = d.img3.Cb[8*(by*d.img3.CStride+bx):], d.img3.CStride
-						case 2:
-							dst, stride = d.img3.Cr[8*(by*d.img3.CStride+bx):], d.img3.CStride
-						case 3:
-							dst, stride = d.blackPix[8*(by*d.blackStride+bx):], d.blackStride
-						default:
-							return UnsupportedError("too many components")
-						}
-					}
-					// Level shift by +128, clip to [0, 255], and write to dst.
-					for y := 0; y < 8; y++ {
-						y8 := y * 8
-						yStride := y * stride
-						for x := 0; x < 8; x++ {
-							c := b[y8+x]
-							if c < -128 {
-								c = 0
-							} else if c > 127 {
-								c = 255
-							} else {
-								c += 128
-							}
-							dst[yStride+x] = uint8(c)
-						}
+					if err := d.reconstructBlock(&b, bx, by, int(compIndex)); err != nil {
+						return err
 					}
 				} // for j
 			} // for i
@@ -470,3 +433,70 @@ func (d *decoder) refineNonZeroes(b *block, zig, zigEnd, nz, delta int32) (int32
 	}
 	return zig, nil
 }
+
+func (d *decoder) reconstructProgressiveImage() error {
+	// The h0, mxx, by and bx variables have the same meaning as in the
+	// processSOS method.
+	h0 := d.comp[0].h
+	mxx := (d.width + 8*h0 - 1) / (8 * h0)
+	for i := 0; i < d.nComp; i++ {
+		if d.progCoeffs[i] == nil {
+			continue
+		}
+		v := 8 * d.comp[0].v / d.comp[i].v
+		h := 8 * d.comp[0].h / d.comp[i].h
+		stride := mxx * d.comp[i].h
+		for by := 0; by*v < d.height; by++ {
+			for bx := 0; bx*h < d.width; bx++ {
+				if err := d.reconstructBlock(&d.progCoeffs[i][by*stride+bx], bx, by, i); err != nil {
+					return err
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// reconstructBlock dequantizes, performs the inverse DCT and stores the block
+// to the image.
+func (d *decoder) reconstructBlock(b *block, bx, by, compIndex int) error {
+	qt := &d.quant[d.comp[compIndex].tq]
+	for zig := 0; zig < blockSize; zig++ {
+		b[unzig[zig]] *= qt[zig]
+	}
+	idct(b)
+	dst, stride := []byte(nil), 0
+	if d.nComp == 1 {
+		dst, stride = d.img1.Pix[8*(by*d.img1.Stride+bx):], d.img1.Stride
+	} else {
+		switch compIndex {
+		case 0:
+			dst, stride = d.img3.Y[8*(by*d.img3.YStride+bx):], d.img3.YStride
+		case 1:
+			dst, stride = d.img3.Cb[8*(by*d.img3.CStride+bx):], d.img3.CStride
+		case 2:
+			dst, stride = d.img3.Cr[8*(by*d.img3.CStride+bx):], d.img3.CStride
+		case 3:
+			dst, stride = d.blackPix[8*(by*d.blackStride+bx):], d.blackStride
+		default:
+			return UnsupportedError("too many components")
+		}
+	}
+	// Level shift by +128, clip to [0, 255], and write to dst.
+	for y := 0; y < 8; y++ {
+		y8 := y * 8
+		yStride := y * stride
+		for x := 0; x < 8; x++ {
+			c := b[y8+x]
+			if c < -128 {
+				c = 0
+			} else if c > 127 {
+				c = 255
+			} else {
+				c += 128
+			}
+			dst[yStride+x] = uint8(c)
+		}
+	}
+	return nil
+}
diff --git a/libgo/go/image/png/reader.go b/libgo/go/image/png/reader.go
index 9e6f985f7e2..2dd5ed80736 100644
--- a/libgo/go/image/png/reader.go
+++ b/libgo/go/image/png/reader.go
@@ -717,6 +717,13 @@ func (d *decoder) parseChunk() error {
 	case "IDAT":
 		if d.stage < dsSeenIHDR || d.stage > dsSeenIDAT || (d.stage == dsSeenIHDR && cbPaletted(d.cb)) {
 			return chunkOrderError
+		} else if d.stage == dsSeenIDAT {
+			// Ignore trailing zero-length or garbage IDAT chunks.
+			//
+			// This does not affect valid PNG images that contain multiple IDAT
+			// chunks, since the first call to parseIDAT below will consume all
+			// consecutive IDAT chunks required for decoding the image.
+			break
 		}
 		d.stage = dsSeenIDAT
 		return d.parseIDAT(length)
diff --git a/libgo/go/image/png/reader_test.go b/libgo/go/image/png/reader_test.go
index f058f6b2275..0bc4203acbe 100644
--- a/libgo/go/image/png/reader_test.go
+++ b/libgo/go/image/png/reader_test.go
@@ -350,6 +350,33 @@ func TestIncompleteIDATOnRowBoundary(t *testing.T) {
 	}
 }
 
+func TestTrailingIDATChunks(t *testing.T) {
+	// The following is a valid 1x1 PNG image containing color.Gray{255} and
+	// a trailing zero-length IDAT chunk (see PNG specification section 12.9):
+	const (
+		ihdr      = "\x00\x00\x00\x0dIHDR\x00\x00\x00\x01\x00\x00\x00\x01\x08\x00\x00\x00\x00\x3a\x7e\x9b\x55"
+		idatWhite = "\x00\x00\x00\x0eIDAT\x78\x9c\x62\xfa\x0f\x08\x00\x00\xff\xff\x01\x05\x01\x02\x5a\xdd\x39\xcd"
+		idatZero  = "\x00\x00\x00\x00IDAT\x35\xaf\x06\x1e"
+		iend      = "\x00\x00\x00\x00IEND\xae\x42\x60\x82"
+	)
+	_, err := Decode(strings.NewReader(pngHeader + ihdr + idatWhite + idatZero + iend))
+	if err != nil {
+		t.Fatalf("decoding valid image: %v", err)
+	}
+
+	// Non-zero-length trailing IDAT chunks should be ignored (recoverable error).
+	// The following chunk contains a single pixel with color.Gray{0}.
+	const idatBlack = "\x00\x00\x00\x0eIDAT\x78\x9c\x62\x62\x00\x04\x00\x00\xff\xff\x00\x06\x00\x03\xfa\xd0\x59\xae"
+
+	img, err := Decode(strings.NewReader(pngHeader + ihdr + idatWhite + idatBlack + iend))
+	if err != nil {
+		t.Fatalf("trailing IDAT not ignored: %v", err)
+	}
+	if img.At(0, 0) == (color.Gray{0}) {
+		t.Fatal("decoded image from trailing IDAT chunk")
+	}
+}
+
 func TestMultipletRNSChunks(t *testing.T) {
 	/*
 		The following is a valid 1x1 paletted PNG image with a 1-element palette
diff --git a/libgo/go/image/testdata/video-001.progressive.truncated.jpeg b/libgo/go/image/testdata/video-001.progressive.truncated.jpeg
new file mode 100644
index 00000000000..b5be8bc7639
--- /dev/null
+++ b/libgo/go/image/testdata/video-001.progressive.truncated.jpeg
diff --git a/libgo/go/image/testdata/video-001.progressive.truncated.png b/libgo/go/image/testdata/video-001.progressive.truncated.png
new file mode 100644
index 00000000000..baf19812265
--- /dev/null
+++ b/libgo/go/image/testdata/video-001.progressive.truncated.png
diff --git a/libgo/go/internal/nettrace/nettrace.go b/libgo/go/internal/nettrace/nettrace.go
new file mode 100644
index 00000000000..de3254df589
--- /dev/null
+++ b/libgo/go/internal/nettrace/nettrace.go
@@ -0,0 +1,45 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package nettrace contains internal hooks for tracing activity in
+// the net package. This package is purely internal for use by the
+// net/http/httptrace package and has no stable API exposed to end
+// users.
+package nettrace
+
+// TraceKey is a context.Context Value key. Its associated value should
+// be a *Trace struct.
+type TraceKey struct{}
+
+// LookupIPAltResolverKey is a context.Context Value key used by tests to
+// specify an alternate resolver func.
+// It is not exposed to outsider users. (But see issue 12503)
+// The value should be the same type as lookupIP:
+//     func lookupIP(ctx context.Context, host string) ([]IPAddr, error)
+type LookupIPAltResolverKey struct{}
+
+// Trace contains a set of hooks for tracing events within
+// the net package. Any specific hook may be nil.
+type Trace struct {
+	// DNSStart is called with the hostname of a DNS lookup
+	// before it begins.
+	DNSStart func(name string)
+
+	// DNSDone is called after a DNS lookup completes (or fails).
+	// The coalesced parameter is whether singleflight de-dupped
+	// the call. The addrs are of type net.IPAddr but can't
+	// actually be for circular dependency reasons.
+	DNSDone func(netIPs []interface{}, coalesced bool, err error)
+
+	// ConnectStart is called before a Dial, excluding Dials made
+	// during DNS lookups. In the case of DualStack (Happy Eyeballs)
+	// dialing, this may be called multiple times, from multiple
+	// goroutines.
+	ConnectStart func(network, addr string)
+
+	// ConnectStart is called after a Dial with the results, excluding
+	// Dials made during DNS lookups. It may also be called multiple
+	// times, like ConnectStart.
+	ConnectDone func(network, addr string, err error)
+}
diff --git a/libgo/go/internal/race/doc.go b/libgo/go/internal/race/doc.go
index d6a2243eb8f..8fa44ce6f19 100644
--- a/libgo/go/internal/race/doc.go
+++ b/libgo/go/internal/race/doc.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/internal/race/norace.go b/libgo/go/internal/race/norace.go
index d9049eb1eb3..7ef5912901f 100644
--- a/libgo/go/internal/race/norace.go
+++ b/libgo/go/internal/race/norace.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/internal/race/race.go b/libgo/go/internal/race/race.go
index cb0e773c442..6c721f6f1dd 100644
--- a/libgo/go/internal/race/race.go
+++ b/libgo/go/internal/race/race.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/internal/singleflight/singleflight.go b/libgo/go/internal/singleflight/singleflight.go
index f4cb2d670d4..de81ac87b9f 100644
--- a/libgo/go/internal/singleflight/singleflight.go
+++ b/libgo/go/internal/singleflight/singleflight.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/internal/singleflight/singleflight_test.go b/libgo/go/internal/singleflight/singleflight_test.go
index c0ec0240c72..5e6f1b328e0 100644
--- a/libgo/go/internal/singleflight/singleflight_test.go
+++ b/libgo/go/internal/singleflight/singleflight_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/internal/syscall/unix/getentropy_openbsd.go b/libgo/go/internal/syscall/unix/getentropy_openbsd.go
new file mode 100644
index 00000000000..d5caa8095a6
--- /dev/null
+++ b/libgo/go/internal/syscall/unix/getentropy_openbsd.go
@@ -0,0 +1,25 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package unix
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// getentropy(2)'s syscall number, from /usr/src/sys/kern/syscalls.master
+const entropyTrap uintptr = 7
+
+// GetEntropy calls the OpenBSD getentropy system call.
+func GetEntropy(p []byte) error {
+	_, _, errno := syscall.Syscall(entropyTrap,
+		uintptr(unsafe.Pointer(&p[0])),
+		uintptr(len(p)),
+		0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux.go b/libgo/go/internal/syscall/unix/getrandom_linux.go
index e07557a93ba..0d0d4f115c0 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_386.go b/libgo/go/internal/syscall/unix/getrandom_linux_386.go
index 48c69b4585e..a583896e683 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_386.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_386.go
@@ -1,7 +1,9 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package unix
 
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
 const randomTrap uintptr = 355
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_amd64.go b/libgo/go/internal/syscall/unix/getrandom_linux_amd64.go
index 7175e36e31e..cff0eb6f052 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_amd64.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_amd64.go
@@ -1,7 +1,9 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package unix
 
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
 const randomTrap uintptr = 318
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_arm.go b/libgo/go/internal/syscall/unix/getrandom_linux_arm.go
index c4d6f43d566..92e2492cd03 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_arm.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_arm.go
@@ -1,7 +1,9 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package unix
 
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
 const randomTrap uintptr = 384
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_generic.go b/libgo/go/internal/syscall/unix/getrandom_linux_generic.go
index 0e632dc27a4..8425800b6da 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_generic.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_generic.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,4 +6,11 @@
 
 package unix
 
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
+//
+// This file is named "generic" because at a certain point Linux
+// started standardizing on system call numbers across
+// architectures. So far this means only arm64 uses the standard
+// numbers.
 const randomTrap uintptr = 278
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_mips64x.go b/libgo/go/internal/syscall/unix/getrandom_linux_mips64x.go
index 8531db68b02..b328b8f1f0e 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_mips64x.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_mips64x.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,4 +6,6 @@
 
 package unix
 
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
 const randomTrap uintptr = 5313
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_ppc64x.go b/libgo/go/internal/syscall/unix/getrandom_linux_ppc64x.go
index 6edaba2f145..9b6e9722be9 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux_ppc64x.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_ppc64x.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,4 +6,6 @@
 
 package unix
 
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
 const randomTrap uintptr = 359
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux_s390x.go b/libgo/go/internal/syscall/unix/getrandom_linux_s390x.go
new file mode 100644
index 00000000000..e3bc4ee355c
--- /dev/null
+++ b/libgo/go/internal/syscall/unix/getrandom_linux_s390x.go
@@ -0,0 +1,9 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package unix
+
+// Linux getrandom system call number.
+// See GetRandom in getrandom_linux.go.
+const randomTrap uintptr = 349
diff --git a/libgo/go/internal/syscall/windows/registry/registry_test.go b/libgo/go/internal/syscall/windows/registry/registry_test.go
index a63c42022d1..56069d7684d 100644
--- a/libgo/go/internal/syscall/windows/registry/registry_test.go
+++ b/libgo/go/internal/syscall/windows/registry/registry_test.go
@@ -213,7 +213,7 @@ func enumerateValues(t *testing.T, k registry.Key) {
 		}
 	}
 	for n, v := range haveNames {
-		t.Errorf("value %s (%v) is found while enumerating, but has not been cretaed", n, v)
+		t.Errorf("value %s (%v) is found while enumerating, but has not been created", n, v)
 	}
 }
 
@@ -335,7 +335,7 @@ func testGetValue(t *testing.T, k registry.Key, test ValueTest, size int) {
 	// read data with short buffer
 	gotsize, gottype, err = k.GetValue(test.Name, make([]byte, size-1))
 	if err == nil {
-		t.Errorf("GetValue(%s, [%d]byte) should fail, but suceeded", test.Name, size-1)
+		t.Errorf("GetValue(%s, [%d]byte) should fail, but succeeded", test.Name, size-1)
 		return
 	}
 	if err != registry.ErrShortBuffer {
diff --git a/libgo/go/internal/syscall/windows/registry/syscall.go b/libgo/go/internal/syscall/windows/registry/syscall.go
index 02d985cec90..5426cae9096 100644
--- a/libgo/go/internal/syscall/windows/registry/syscall.go
+++ b/libgo/go/internal/syscall/windows/registry/syscall.go
@@ -8,7 +8,7 @@ package registry
 
 import "syscall"
 
-//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go -systemdll syscall.go
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zsyscall_windows.go syscall.go
 
 const (
 	_REG_OPTION_NON_VOLATILE = 0
diff --git a/libgo/go/internal/syscall/windows/registry/zsyscall_windows.go b/libgo/go/internal/syscall/windows/registry/zsyscall_windows.go
index 7e473d4e1de..62affc0b50b 100644
--- a/libgo/go/internal/syscall/windows/registry/zsyscall_windows.go
+++ b/libgo/go/internal/syscall/windows/registry/zsyscall_windows.go
@@ -2,9 +2,11 @@
 
 package registry
 
-import "unsafe"
-import "syscall"
-import "internal/syscall/windows/sysdll"
+import (
+	"internal/syscall/windows/sysdll"
+	"syscall"
+	"unsafe"
+)
 
 var _ unsafe.Pointer
 
diff --git a/libgo/go/internal/syscall/windows/syscall_windows.go b/libgo/go/internal/syscall/windows/syscall_windows.go
index e6a3f238d88..7b2bc79cebe 100644
--- a/libgo/go/internal/syscall/windows/syscall_windows.go
+++ b/libgo/go/internal/syscall/windows/syscall_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,7 +6,7 @@ package windows
 
 import "syscall"
 
-//go:generate go run ../../../syscall/mksyscall_windows.go -output zsyscall_windows.go -systemdll syscall_windows.go
+//go:generate go run ../../../syscall/mksyscall_windows.go -output zsyscall_windows.go syscall_windows.go
 
 const GAA_FLAG_INCLUDE_PREFIX = 0x00000010
 
diff --git a/libgo/go/internal/syscall/windows/zsyscall_windows.go b/libgo/go/internal/syscall/windows/zsyscall_windows.go
index d599258976b..6929acfa728 100644
--- a/libgo/go/internal/syscall/windows/zsyscall_windows.go
+++ b/libgo/go/internal/syscall/windows/zsyscall_windows.go
@@ -2,9 +2,11 @@
 
 package windows
 
-import "unsafe"
-import "syscall"
-import "internal/syscall/windows/sysdll"
+import (
+	"internal/syscall/windows/sysdll"
+	"syscall"
+	"unsafe"
+)
 
 var _ unsafe.Pointer
 
diff --git a/libgo/go/internal/testenv/testenv.go b/libgo/go/internal/testenv/testenv.go
index 10719084bbb..e76e33956d1 100644
--- a/libgo/go/internal/testenv/testenv.go
+++ b/libgo/go/internal/testenv/testenv.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -11,8 +11,12 @@
 package testenv
 
 import (
+	"flag"
 	"os"
+	"os/exec"
+	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"testing"
 )
@@ -65,6 +69,29 @@ func MustHaveGoRun(t *testing.T) {
 	}
 }
 
+// GoToolPath reports the path to the Go tool.
+// If the tool is unavailable GoToolPath calls t.Skip.
+// If the tool should be available and isn't, GoToolPath calls t.Fatal.
+func GoToolPath(t *testing.T) string {
+	MustHaveGoBuild(t)
+
+	var exeSuffix string
+	if runtime.GOOS == "windows" {
+		exeSuffix = ".exe"
+	}
+
+	path := filepath.Join(runtime.GOROOT(), "bin", "go"+exeSuffix)
+	if _, err := os.Stat(path); err == nil {
+		return path
+	}
+
+	goBin, err := exec.LookPath("go" + exeSuffix)
+	if err != nil {
+		t.Fatalf("cannot find go tool: %v", err)
+	}
+	return goBin
+}
+
 // HasExec reports whether the current system can start new processes
 // using os.StartProcess or (more commonly) exec.Command.
 func HasExec() bool {
@@ -102,3 +129,17 @@ func MustHaveExternalNetwork(t *testing.T) {
 		t.Skipf("skipping test: no external network in -short mode")
 	}
 }
+
+var flaky = flag.Bool("flaky", false, "run known-flaky tests too")
+
+func SkipFlaky(t *testing.T, issue int) {
+	if !*flaky {
+		t.Skipf("skipping known flaky test without the -flaky flag; see golang.org/issue/%d", issue)
+	}
+}
+
+func SkipFlakyNet(t *testing.T) {
+	if v, _ := strconv.ParseBool(os.Getenv("GO_BUILDER_FLAKY_NET")); v {
+		t.Skip("skipping test on builder known to have frequent network failures")
+	}
+}
diff --git a/libgo/go/internal/trace/order.go b/libgo/go/internal/trace/order.go
new file mode 100644
index 00000000000..8ca2da52aa6
--- /dev/null
+++ b/libgo/go/internal/trace/order.go
@@ -0,0 +1,278 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package trace
+
+import (
+	"fmt"
+	"sort"
+)
+
+type eventBatch struct {
+	events   []*Event
+	selected bool
+}
+
+type orderEvent struct {
+	ev    *Event
+	batch int
+	g     uint64
+	init  gState
+	next  gState
+}
+
+type gStatus int
+
+type gState struct {
+	seq    uint64
+	status gStatus
+}
+
+const (
+	gDead gStatus = iota
+	gRunnable
+	gRunning
+	gWaiting
+
+	unordered = ^uint64(0)
+	garbage   = ^uint64(0) - 1
+	noseq     = ^uint64(0)
+	seqinc    = ^uint64(0) - 1
+)
+
+// order1007 merges a set of per-P event batches into a single, consistent stream.
+// The high level idea is as follows. Events within an individual batch are in
+// correct order, because they are emitted by a single P. So we need to produce
+// a correct interleaving of the batches. To do this we take first unmerged event
+// from each batch (frontier). Then choose subset that is "ready" to be merged,
+// that is, events for which all dependencies are already merged. Then we choose
+// event with the lowest timestamp from the subset, merge it and repeat.
+// This approach ensures that we form a consistent stream even if timestamps are
+// incorrect (condition observed on some machines).
+func order1007(m map[int][]*Event) (events []*Event, err error) {
+	pending := 0
+	var batches []*eventBatch
+	for _, v := range m {
+		pending += len(v)
+		batches = append(batches, &eventBatch{v, false})
+	}
+	gs := make(map[uint64]gState)
+	var frontier []orderEvent
+	for ; pending != 0; pending-- {
+		for i, b := range batches {
+			if b.selected || len(b.events) == 0 {
+				continue
+			}
+			ev := b.events[0]
+			g, init, next := stateTransition(ev)
+			if !transitionReady(g, gs[g], init) {
+				continue
+			}
+			frontier = append(frontier, orderEvent{ev, i, g, init, next})
+			b.events = b.events[1:]
+			b.selected = true
+			// Get rid of "Local" events, they are intended merely for ordering.
+			switch ev.Type {
+			case EvGoStartLocal:
+				ev.Type = EvGoStart
+			case EvGoUnblockLocal:
+				ev.Type = EvGoUnblock
+			case EvGoSysExitLocal:
+				ev.Type = EvGoSysExit
+			}
+		}
+		if len(frontier) == 0 {
+			return nil, fmt.Errorf("no consistent ordering of events possible")
+		}
+		sort.Sort(orderEventList(frontier))
+		f := frontier[0]
+		frontier[0] = frontier[len(frontier)-1]
+		frontier = frontier[:len(frontier)-1]
+		events = append(events, f.ev)
+		transition(gs, f.g, f.init, f.next)
+		if !batches[f.batch].selected {
+			panic("frontier batch is not selected")
+		}
+		batches[f.batch].selected = false
+	}
+
+	// At this point we have a consistent stream of events.
+	// Make sure time stamps respect the ordering.
+	// The tests will skip (not fail) the test case if they see this error.
+	if !sort.IsSorted(eventList(events)) {
+		return nil, ErrTimeOrder
+	}
+
+	// The last part is giving correct timestamps to EvGoSysExit events.
+	// The problem with EvGoSysExit is that actual syscall exit timestamp (ev.Args[2])
+	// is potentially acquired long before event emission. So far we've used
+	// timestamp of event emission (ev.Ts).
+	// We could not set ev.Ts = ev.Args[2] earlier, because it would produce
+	// seemingly broken timestamps (misplaced event).
+	// We also can't simply update the timestamp and resort events, because
+	// if timestamps are broken we will misplace the event and later report
+	// logically broken trace (instead of reporting broken timestamps).
+	lastSysBlock := make(map[uint64]int64)
+	for _, ev := range events {
+		switch ev.Type {
+		case EvGoSysBlock, EvGoInSyscall:
+			lastSysBlock[ev.G] = ev.Ts
+		case EvGoSysExit:
+			ts := int64(ev.Args[2])
+			if ts == 0 {
+				continue
+			}
+			block := lastSysBlock[ev.G]
+			if block == 0 {
+				return nil, fmt.Errorf("stray syscall exit")
+			}
+			if ts < block {
+				return nil, ErrTimeOrder
+			}
+			ev.Ts = ts
+		}
+	}
+	sort.Stable(eventList(events))
+
+	return
+}
+
+// stateTransition returns goroutine state (sequence and status) when the event
+// becomes ready for merging (init) and the goroutine state after the event (next).
+func stateTransition(ev *Event) (g uint64, init, next gState) {
+	switch ev.Type {
+	case EvGoCreate:
+		g = ev.Args[0]
+		init = gState{0, gDead}
+		next = gState{1, gRunnable}
+	case EvGoWaiting, EvGoInSyscall:
+		g = ev.G
+		init = gState{1, gRunnable}
+		next = gState{2, gWaiting}
+	case EvGoStart:
+		g = ev.G
+		init = gState{ev.Args[1], gRunnable}
+		next = gState{ev.Args[1] + 1, gRunning}
+	case EvGoStartLocal:
+		// noseq means that this event is ready for merging as soon as
+		// frontier reaches it (EvGoStartLocal is emitted on the same P
+		// as the corresponding EvGoCreate/EvGoUnblock, and thus the latter
+		// is already merged).
+		// seqinc is a stub for cases when event increments g sequence,
+		// but since we don't know current seq we also don't know next seq.
+		g = ev.G
+		init = gState{noseq, gRunnable}
+		next = gState{seqinc, gRunning}
+	case EvGoBlock, EvGoBlockSend, EvGoBlockRecv, EvGoBlockSelect,
+		EvGoBlockSync, EvGoBlockCond, EvGoBlockNet, EvGoSleep, EvGoSysBlock:
+		g = ev.G
+		init = gState{noseq, gRunning}
+		next = gState{noseq, gWaiting}
+	case EvGoSched, EvGoPreempt:
+		g = ev.G
+		init = gState{noseq, gRunning}
+		next = gState{noseq, gRunnable}
+	case EvGoUnblock, EvGoSysExit:
+		g = ev.Args[0]
+		init = gState{ev.Args[1], gWaiting}
+		next = gState{ev.Args[1] + 1, gRunnable}
+	case EvGoUnblockLocal, EvGoSysExitLocal:
+		g = ev.Args[0]
+		init = gState{noseq, gWaiting}
+		next = gState{seqinc, gRunnable}
+	case EvGCStart:
+		g = garbage
+		init = gState{ev.Args[0], gDead}
+		next = gState{ev.Args[0] + 1, gDead}
+	default:
+		// no ordering requirements
+		g = unordered
+	}
+	return
+}
+
+func transitionReady(g uint64, curr, init gState) bool {
+	return g == unordered || (init.seq == noseq || init.seq == curr.seq) && init.status == curr.status
+}
+
+func transition(gs map[uint64]gState, g uint64, init, next gState) {
+	if g == unordered {
+		return
+	}
+	curr := gs[g]
+	if !transitionReady(g, curr, init) {
+		panic("event sequences are broken")
+	}
+	switch next.seq {
+	case noseq:
+		next.seq = curr.seq
+	case seqinc:
+		next.seq = curr.seq + 1
+	}
+	gs[g] = next
+}
+
+// order1005 merges a set of per-P event batches into a single, consistent stream.
+func order1005(m map[int][]*Event) (events []*Event, err error) {
+	for _, batch := range m {
+		events = append(events, batch...)
+	}
+	for _, ev := range events {
+		if ev.Type == EvGoSysExit {
+			// EvGoSysExit emission is delayed until the thread has a P.
+			// Give it the real sequence number and time stamp.
+			ev.seq = int64(ev.Args[1])
+			if ev.Args[2] != 0 {
+				ev.Ts = int64(ev.Args[2])
+			}
+		}
+	}
+	sort.Sort(eventSeqList(events))
+	if !sort.IsSorted(eventList(events)) {
+		return nil, ErrTimeOrder
+	}
+	return
+}
+
+type orderEventList []orderEvent
+
+func (l orderEventList) Len() int {
+	return len(l)
+}
+
+func (l orderEventList) Less(i, j int) bool {
+	return l[i].ev.Ts < l[j].ev.Ts
+}
+
+func (l orderEventList) Swap(i, j int) {
+	l[i], l[j] = l[j], l[i]
+}
+
+type eventList []*Event
+
+func (l eventList) Len() int {
+	return len(l)
+}
+
+func (l eventList) Less(i, j int) bool {
+	return l[i].Ts < l[j].Ts
+}
+
+func (l eventList) Swap(i, j int) {
+	l[i], l[j] = l[j], l[i]
+}
+
+type eventSeqList []*Event
+
+func (l eventSeqList) Len() int {
+	return len(l)
+}
+
+func (l eventSeqList) Less(i, j int) bool {
+	return l[i].seq < l[j].seq
+}
+
+func (l eventSeqList) Swap(i, j int) {
+	l[i], l[j] = l[j], l[i]
+}
diff --git a/libgo/go/internal/trace/parser.go b/libgo/go/internal/trace/parser.go
index 11f9aba6162..c31517f683f 100644
--- a/libgo/go/internal/trace/parser.go
+++ b/libgo/go/internal/trace/parser.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -9,18 +9,19 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"math/rand"
 	"os"
 	"os/exec"
-	"sort"
 	"strconv"
 	"strings"
+	_ "unsafe"
 )
 
 // Event describes one event in the trace.
 type Event struct {
 	Off   int       // offset in input file (for debugging and error reporting)
 	Type  byte      // one of Ev*
-	Seq   int64     // sequence number
+	seq   int64     // sequence number
 	Ts    int64     // timestamp in nanoseconds
 	P     int       // P on which the event happened (can be one of TimerP, NetpollP, SyscallP)
 	G     uint64    // G on which the event happened
@@ -58,24 +59,48 @@ const (
 )
 
 // Parse parses, post-processes and verifies the trace.
-func Parse(r io.Reader) ([]*Event, error) {
-	rawEvents, err := readTrace(r)
+func Parse(r io.Reader, bin string) ([]*Event, error) {
+	ver, events, err := parse(r, bin)
 	if err != nil {
 		return nil, err
 	}
-	events, err := parseEvents(rawEvents)
+	if ver < 1007 && bin == "" {
+		return nil, fmt.Errorf("for traces produced by go 1.6 or below, the binary argument must be provided")
+	}
+	return events, nil
+}
+
+// parse parses, post-processes and verifies the trace. It returns the
+// trace version and the list of events.
+func parse(r io.Reader, bin string) (int, []*Event, error) {
+	ver, rawEvents, strings, err := readTrace(r)
 	if err != nil {
-		return nil, err
+		return 0, nil, err
+	}
+	events, stacks, err := parseEvents(ver, rawEvents, strings)
+	if err != nil {
+		return 0, nil, err
 	}
 	events, err = removeFutile(events)
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}
-	err = postProcessTrace(events)
+	err = postProcessTrace(ver, events)
 	if err != nil {
-		return nil, err
+		return 0, nil, err
 	}
-	return events, nil
+	// Attach stack traces.
+	for _, ev := range events {
+		if ev.StkID != 0 {
+			ev.Stk = stacks[ev.StkID]
+		}
+	}
+	if ver < 1007 && bin != "" {
+		if err := symbolize(events, bin); err != nil {
+			return 0, nil, err
+		}
+	}
+	return ver, events, nil
 }
 
 // rawEvent is a helper type used during parsing.
@@ -87,107 +112,187 @@ type rawEvent struct {
 
 // readTrace does wire-format parsing and verification.
 // It does not care about specific event types and argument meaning.
-func readTrace(r io.Reader) ([]rawEvent, error) {
+func readTrace(r io.Reader) (ver int, events []rawEvent, strings map[uint64]string, err error) {
 	// Read and validate trace header.
 	var buf [16]byte
-	off, err := r.Read(buf[:])
-	if off != 16 || err != nil {
-		return nil, fmt.Errorf("failed to read header: read %v, err %v", off, err)
+	off, err := io.ReadFull(r, buf[:])
+	if err != nil {
+		err = fmt.Errorf("failed to read header: read %v, err %v", off, err)
+		return
+	}
+	ver, err = parseHeader(buf[:])
+	if err != nil {
+		return
 	}
-	if bytes.Compare(buf[:], []byte("go 1.5 trace\x00\x00\x00\x00")) != 0 {
-		return nil, fmt.Errorf("not a trace file")
+	switch ver {
+	case 1005, 1007:
+		break
+	default:
+		err = fmt.Errorf("unsupported trace file version %v.%v (update Go toolchain) %v", ver/1000, ver%1000, ver)
+		return
 	}
 
 	// Read events.
-	var events []rawEvent
+	strings = make(map[uint64]string)
 	for {
 		// Read event type and number of arguments (1 byte).
 		off0 := off
-		n, err := r.Read(buf[:1])
+		var n int
+		n, err = r.Read(buf[:1])
 		if err == io.EOF {
+			err = nil
 			break
 		}
 		if err != nil || n != 1 {
-			return nil, fmt.Errorf("failed to read trace at offset 0x%x: n=%v err=%v", off0, n, err)
+			err = fmt.Errorf("failed to read trace at offset 0x%x: n=%v err=%v", off0, n, err)
+			return
 		}
 		off += n
 		typ := buf[0] << 2 >> 2
-		narg := buf[0] >> 6
+		narg := buf[0]>>6 + 1
+		inlineArgs := byte(4)
+		if ver < 1007 {
+			narg++
+			inlineArgs++
+		}
+		if typ == EvNone || typ >= EvCount || EventDescriptions[typ].minVersion > ver {
+			err = fmt.Errorf("unknown event type %v at offset 0x%x", typ, off0)
+			return
+		}
+		if typ == EvString {
+			// String dictionary entry [ID, length, string].
+			var id uint64
+			id, off, err = readVal(r, off)
+			if err != nil {
+				return
+			}
+			if id == 0 {
+				err = fmt.Errorf("string at offset %d has invalid id 0", off)
+				return
+			}
+			if strings[id] != "" {
+				err = fmt.Errorf("string at offset %d has duplicate id %v", off, id)
+				return
+			}
+			var ln uint64
+			ln, off, err = readVal(r, off)
+			if err != nil {
+				return
+			}
+			if ln == 0 {
+				err = fmt.Errorf("string at offset %d has invalid length 0", off)
+				return
+			}
+			if ln > 1e6 {
+				err = fmt.Errorf("string at offset %d has too large length %v", off, ln)
+				return
+			}
+			buf := make([]byte, ln)
+			var n int
+			n, err = io.ReadFull(r, buf)
+			if err != nil {
+				err = fmt.Errorf("failed to read trace at offset %d: read %v, want %v, error %v", off, n, ln, err)
+				return
+			}
+			off += n
+			strings[id] = string(buf)
+			continue
+		}
 		ev := rawEvent{typ: typ, off: off0}
-		if narg < 3 {
-			for i := 0; i < int(narg)+2; i++ { // sequence number and time stamp are present but not counted in narg
+		if narg < inlineArgs {
+			for i := 0; i < int(narg); i++ {
 				var v uint64
 				v, off, err = readVal(r, off)
 				if err != nil {
-					return nil, err
+					err = fmt.Errorf("failed to read event %v argument at offset %v (%v)", typ, off, err)
+					return
 				}
 				ev.args = append(ev.args, v)
 			}
 		} else {
-			// If narg == 3, the first value is length of the event in bytes.
+			// More than inlineArgs args, the first value is length of the event in bytes.
 			var v uint64
 			v, off, err = readVal(r, off)
 			if err != nil {
-				return nil, err
+				err = fmt.Errorf("failed to read event %v argument at offset %v (%v)", typ, off, err)
+				return
 			}
 			evLen := v
 			off1 := off
 			for evLen > uint64(off-off1) {
 				v, off, err = readVal(r, off)
 				if err != nil {
-					return nil, err
+					err = fmt.Errorf("failed to read event %v argument at offset %v (%v)", typ, off, err)
+					return
 				}
 				ev.args = append(ev.args, v)
 			}
 			if evLen != uint64(off-off1) {
-				return nil, fmt.Errorf("event has wrong length at offset 0x%x: want %v, got %v", off0, evLen, off-off1)
+				err = fmt.Errorf("event has wrong length at offset 0x%x: want %v, got %v", off0, evLen, off-off1)
+				return
 			}
 		}
 		events = append(events, ev)
 	}
-	return events, nil
+	return
+}
+
+// parseHeader parses trace header of the form "go 1.7 trace\x00\x00\x00\x00"
+// and returns parsed version as 1007.
+func parseHeader(buf []byte) (int, error) {
+	if len(buf) != 16 {
+		return 0, fmt.Errorf("bad header length")
+	}
+	if buf[0] != 'g' || buf[1] != 'o' || buf[2] != ' ' ||
+		buf[3] < '1' || buf[3] > '9' ||
+		buf[4] != '.' ||
+		buf[5] < '1' || buf[5] > '9' {
+		return 0, fmt.Errorf("not a trace file")
+	}
+	ver := int(buf[5] - '0')
+	i := 0
+	for ; buf[6+i] >= '0' && buf[6+i] <= '9' && i < 2; i++ {
+		ver = ver*10 + int(buf[6+i]-'0')
+	}
+	ver += int(buf[3]-'0') * 1000
+	if !bytes.Equal(buf[6+i:], []byte(" trace\x00\x00\x00\x00")[:10-i]) {
+		return 0, fmt.Errorf("not a trace file")
+	}
+	return ver, nil
 }
 
 // Parse events transforms raw events into events.
 // It does analyze and verify per-event-type arguments.
-func parseEvents(rawEvents []rawEvent) (events []*Event, err error) {
+func parseEvents(ver int, rawEvents []rawEvent, strings map[uint64]string) (events []*Event, stacks map[uint64][]*Frame, err error) {
 	var ticksPerSec, lastSeq, lastTs int64
 	var lastG, timerGoid uint64
 	var lastP int
 	lastGs := make(map[int]uint64) // last goroutine running on P
-	stacks := make(map[uint64][]*Frame)
+	stacks = make(map[uint64][]*Frame)
+	batches := make(map[int][]*Event) // events by P
 	for _, raw := range rawEvents {
-		if raw.typ == EvNone || raw.typ >= EvCount {
-			err = fmt.Errorf("unknown event type %v at offset 0x%x", raw.typ, raw.off)
-			return
-		}
 		desc := EventDescriptions[raw.typ]
 		if desc.Name == "" {
 			err = fmt.Errorf("missing description for event type %v", raw.typ)
 			return
 		}
-		if raw.typ != EvStack {
-			narg := len(desc.Args)
-			if desc.Stack {
-				narg++
-			}
-			if raw.typ != EvBatch && raw.typ != EvFrequency && raw.typ != EvTimerGoroutine {
-				narg++ // sequence number
-				narg++ // timestamp
-			}
-			if len(raw.args) != narg {
-				err = fmt.Errorf("%v has wrong number of arguments at offset 0x%x: want %v, got %v",
-					desc.Name, raw.off, narg, len(raw.args))
-				return
-			}
+		narg := argNum(raw, ver)
+		if len(raw.args) != narg {
+			err = fmt.Errorf("%v has wrong number of arguments at offset 0x%x: want %v, got %v",
+				desc.Name, raw.off, narg, len(raw.args))
+			return
 		}
 		switch raw.typ {
 		case EvBatch:
 			lastGs[lastP] = lastG
 			lastP = int(raw.args[0])
 			lastG = lastGs[lastP]
-			lastSeq = int64(raw.args[1])
-			lastTs = int64(raw.args[2])
+			if ver < 1007 {
+				lastSeq = int64(raw.args[1])
+				lastTs = int64(raw.args[2])
+			} else {
+				lastTs = int64(raw.args[1])
+			}
 		case EvFrequency:
 			ticksPerSec = int64(raw.args[0])
 			if ticksPerSec <= 0 {
@@ -211,33 +316,53 @@ func parseEvents(rawEvents []rawEvent) (events []*Event, err error) {
 					raw.off, size)
 				return
 			}
-			if uint64(len(raw.args)) != size+2 {
+			want := 2 + 4*size
+			if ver < 1007 {
+				want = 2 + size
+			}
+			if uint64(len(raw.args)) != want {
 				err = fmt.Errorf("EvStack has wrong number of arguments at offset 0x%x: want %v, got %v",
-					raw.off, size+2, len(raw.args))
+					raw.off, want, len(raw.args))
 				return
 			}
 			id := raw.args[0]
 			if id != 0 && size > 0 {
 				stk := make([]*Frame, size)
 				for i := 0; i < int(size); i++ {
-					stk[i] = &Frame{PC: raw.args[i+2]}
+					if ver < 1007 {
+						stk[i] = &Frame{PC: raw.args[2+i]}
+					} else {
+						pc := raw.args[2+i*4+0]
+						fn := raw.args[2+i*4+1]
+						file := raw.args[2+i*4+2]
+						line := raw.args[2+i*4+3]
+						stk[i] = &Frame{PC: pc, Fn: strings[fn], File: strings[file], Line: int(line)}
+					}
 				}
 				stacks[id] = stk
 			}
 		default:
 			e := &Event{Off: raw.off, Type: raw.typ, P: lastP, G: lastG}
-			e.Seq = lastSeq + int64(raw.args[0])
-			e.Ts = lastTs + int64(raw.args[1])
-			lastSeq = e.Seq
-			lastTs = e.Ts
-			for i := range desc.Args {
-				e.Args[i] = raw.args[i+2]
+			var argOffset int
+			if ver < 1007 {
+				e.seq = lastSeq + int64(raw.args[0])
+				e.Ts = lastTs + int64(raw.args[1])
+				lastSeq = e.seq
+				argOffset = 2
+			} else {
+				e.Ts = lastTs + int64(raw.args[0])
+				argOffset = 1
 			}
-			if desc.Stack {
-				e.StkID = raw.args[len(desc.Args)+2]
+			lastTs = e.Ts
+			for i := argOffset; i < narg; i++ {
+				if i == narg-1 && desc.Stack {
+					e.StkID = raw.args[i]
+				} else {
+					e.Args[i-argOffset] = raw.args[i]
+				}
 			}
 			switch raw.typ {
-			case EvGoStart:
+			case EvGoStart, EvGoStartLocal:
 				lastG = e.Args[0]
 				e.G = lastG
 			case EvGCStart, EvGCDone, EvGCScanStart, EvGCScanDone:
@@ -247,45 +372,51 @@ func parseEvents(rawEvents []rawEvent) (events []*Event, err error) {
 				EvGoBlockSelect, EvGoBlockSync, EvGoBlockCond, EvGoBlockNet,
 				EvGoSysBlock:
 				lastG = 0
-			case EvGoSysExit:
-				// EvGoSysExit emission is delayed until the thread has a P.
-				// Give it the real sequence number and time stamp.
-				e.Seq = int64(e.Args[1])
-				if e.Args[2] != 0 {
-					e.Ts = int64(e.Args[2])
-				}
+			case EvGoSysExit, EvGoWaiting, EvGoInSyscall:
+				e.G = e.Args[0]
 			}
-			events = append(events, e)
+			batches[lastP] = append(batches[lastP], e)
 		}
 	}
-	if len(events) == 0 {
+	if len(batches) == 0 {
 		err = fmt.Errorf("trace is empty")
 		return
 	}
-
-	// Attach stack traces.
-	for _, ev := range events {
-		if ev.StkID != 0 {
-			ev.Stk = stacks[ev.StkID]
-		}
-	}
-
-	// Sort by sequence number and translate cpu ticks to real time.
-	sort.Sort(eventList(events))
 	if ticksPerSec == 0 {
 		err = fmt.Errorf("no EvFrequency event")
 		return
 	}
+	if BreakTimestampsForTesting {
+		var batchArr [][]*Event
+		for _, batch := range batches {
+			batchArr = append(batchArr, batch)
+		}
+		for i := 0; i < 5; i++ {
+			batch := batchArr[rand.Intn(len(batchArr))]
+			batch[rand.Intn(len(batch))].Ts += int64(rand.Intn(2000) - 1000)
+		}
+	}
+	if ver < 1007 {
+		events, err = order1005(batches)
+	} else {
+		events, err = order1007(batches)
+	}
+	if err != nil {
+		return
+	}
+
+	// Translate cpu ticks to real time.
 	minTs := events[0].Ts
+	// Use floating point to avoid integer overflows.
+	freq := 1e9 / float64(ticksPerSec)
 	for _, ev := range events {
-		ev.Ts = (ev.Ts - minTs) * 1e9 / ticksPerSec
+		ev.Ts = int64(float64(ev.Ts-minTs) * freq)
 		// Move timers and syscalls to separate fake Ps.
 		if timerGoid != 0 && ev.G == timerGoid && ev.Type == EvGoUnblock {
 			ev.P = TimerP
 		}
 		if ev.Type == EvGoSysExit {
 			ev.P = SyscallP
-			ev.G = ev.Args[0]
 		}
 	}
 
@@ -355,7 +486,7 @@ var ErrTimeOrder = fmt.Errorf("time stamps out of order")
 // The resulting trace is guaranteed to be consistent
 // (for example, a P does not run two Gs at the same time, or a G is indeed
 // blocked before an unblock event).
-func postProcessTrace(events []*Event) error {
+func postProcessTrace(ver int, events []*Event) error {
 	const (
 		gDead = iota
 		gRunnable
@@ -446,19 +577,15 @@ func postProcessTrace(events []*Event) error {
 			p.evSweep.Link = ev
 			p.evSweep = nil
 		case EvGoWaiting:
-			g1 := gs[ev.Args[0]]
-			if g1.state != gRunnable {
-				return fmt.Errorf("g %v is not runnable before EvGoWaiting (offset %v, time %v)", ev.Args[0], ev.Off, ev.Ts)
+			if g.state != gRunnable {
+				return fmt.Errorf("g %v is not runnable before EvGoWaiting (offset %v, time %v)", ev.G, ev.Off, ev.Ts)
 			}
-			g1.state = gWaiting
-			gs[ev.Args[0]] = g1
+			g.state = gWaiting
 		case EvGoInSyscall:
-			g1 := gs[ev.Args[0]]
-			if g1.state != gRunnable {
-				return fmt.Errorf("g %v is not runnable before EvGoInSyscall (offset %v, time %v)", ev.Args[0], ev.Off, ev.Ts)
+			if g.state != gRunnable {
+				return fmt.Errorf("g %v is not runnable before EvGoInSyscall (offset %v, time %v)", ev.G, ev.Off, ev.Ts)
 			}
-			g1.state = gWaiting
-			gs[ev.Args[0]] = g1
+			g.state = gWaiting
 		case EvGoCreate:
 			if err := checkRunning(p, g, ev, true); err != nil {
 				return err
@@ -478,8 +605,12 @@ func postProcessTrace(events []*Event) error {
 			g.evStart = ev
 			p.g = ev.G
 			if g.evCreate != nil {
-				// +1 because symbolizer expects return pc.
-				ev.Stk = []*Frame{{PC: g.evCreate.Args[1] + 1}}
+				if ver < 1007 {
+					// +1 because symbolizer expects return pc.
+					ev.Stk = []*Frame{{PC: g.evCreate.Args[1] + 1}}
+				} else {
+					ev.StkID = g.evCreate.Args[1]
+				}
 				g.evCreate = nil
 			}
 
@@ -565,23 +696,11 @@ func postProcessTrace(events []*Event) error {
 	// TODO(dvyukov): restore stacks for EvGoStart events.
 	// TODO(dvyukov): test that all EvGoStart events has non-nil Link.
 
-	// Last, after all the other consistency checks,
-	// make sure time stamps respect sequence numbers.
-	// The tests will skip (not fail) the test case if they see this error,
-	// so check everything else that could possibly be wrong first.
-	lastTs := int64(0)
-	for _, ev := range events {
-		if ev.Ts < lastTs {
-			return ErrTimeOrder
-		}
-		lastTs = ev.Ts
-	}
-
 	return nil
 }
 
-// symbolizeTrace attaches func/file/line info to stack traces.
-func Symbolize(events []*Event, bin string) error {
+// symbolize attaches func/file/line info to stack traces.
+func symbolize(events []*Event, bin string) error {
 	// First, collect and dedup all pcs.
 	pcs := make(map[uint64]*Frame)
 	for _, ev := range events {
@@ -672,57 +791,81 @@ func readVal(r io.Reader, off0 int) (v uint64, off int, err error) {
 	return 0, 0, fmt.Errorf("bad value at offset 0x%x", off0)
 }
 
-type eventList []*Event
-
-func (l eventList) Len() int {
-	return len(l)
-}
-
-func (l eventList) Less(i, j int) bool {
-	return l[i].Seq < l[j].Seq
+// Print dumps events to stdout. For debugging.
+func Print(events []*Event) {
+	for _, ev := range events {
+		PrintEvent(ev)
+	}
 }
 
-func (l eventList) Swap(i, j int) {
-	l[i], l[j] = l[j], l[i]
+// PrintEvent dumps the event to stdout. For debugging.
+func PrintEvent(ev *Event) {
+	desc := EventDescriptions[ev.Type]
+	fmt.Printf("%v %v p=%v g=%v off=%v", ev.Ts, desc.Name, ev.P, ev.G, ev.Off)
+	for i, a := range desc.Args {
+		fmt.Printf(" %v=%v", a, ev.Args[i])
+	}
+	fmt.Printf("\n")
 }
 
-// Print dumps events to stdout. For debugging.
-func Print(events []*Event) {
-	for _, ev := range events {
-		desc := EventDescriptions[ev.Type]
-		fmt.Printf("%v %v p=%v g=%v off=%v", ev.Ts, desc.Name, ev.P, ev.G, ev.Off)
-		for i, a := range desc.Args {
-			fmt.Printf(" %v=%v", a, ev.Args[i])
+// argNum returns total number of args for the event accounting for timestamps,
+// sequence numbers and differences between trace format versions.
+func argNum(raw rawEvent, ver int) int {
+	desc := EventDescriptions[raw.typ]
+	if raw.typ == EvStack {
+		return len(raw.args)
+	}
+	narg := len(desc.Args)
+	if desc.Stack {
+		narg++
+	}
+	switch raw.typ {
+	case EvBatch, EvFrequency, EvTimerGoroutine:
+		if ver < 1007 {
+			narg++ // there was an unused arg before 1.7
+		}
+	case EvGCStart, EvGoStart, EvGoUnblock:
+		if ver < 1007 {
+			narg-- // 1.7 added an additional seq arg
+		}
+		fallthrough
+	default:
+		narg++ // timestamp
+		if ver < 1007 {
+			narg++ // sequence
 		}
-		fmt.Printf("\n")
 	}
+	return narg
 }
 
+// BreakTimestampsForTesting causes the parser to randomly alter timestamps (for testing of broken cputicks).
+var BreakTimestampsForTesting bool
+
 // Event types in the trace.
 // Verbatim copy from src/runtime/trace.go.
 const (
 	EvNone           = 0  // unused
 	EvBatch          = 1  // start of per-P batch of events [pid, timestamp]
 	EvFrequency      = 2  // contains tracer timer frequency [frequency (ticks per second)]
-	EvStack          = 3  // stack [stack id, number of PCs, array of PCs]
+	EvStack          = 3  // stack [stack id, number of PCs, array of {PC, func string ID, file string ID, line}]
 	EvGomaxprocs     = 4  // current value of GOMAXPROCS [timestamp, GOMAXPROCS, stack id]
 	EvProcStart      = 5  // start of P [timestamp, thread id]
 	EvProcStop       = 6  // stop of P [timestamp]
-	EvGCStart        = 7  // GC start [timestamp, stack id]
+	EvGCStart        = 7  // GC start [timestamp, seq, stack id]
 	EvGCDone         = 8  // GC done [timestamp]
 	EvGCScanStart    = 9  // GC scan start [timestamp]
 	EvGCScanDone     = 10 // GC scan done [timestamp]
 	EvGCSweepStart   = 11 // GC sweep start [timestamp, stack id]
 	EvGCSweepDone    = 12 // GC sweep done [timestamp]
-	EvGoCreate       = 13 // goroutine creation [timestamp, new goroutine id, start PC, stack id]
-	EvGoStart        = 14 // goroutine starts running [timestamp, goroutine id]
+	EvGoCreate       = 13 // goroutine creation [timestamp, new goroutine id, new stack id, stack id]
+	EvGoStart        = 14 // goroutine starts running [timestamp, goroutine id, seq]
 	EvGoEnd          = 15 // goroutine ends [timestamp]
 	EvGoStop         = 16 // goroutine stops (like in select{}) [timestamp, stack]
 	EvGoSched        = 17 // goroutine calls Gosched [timestamp, stack]
 	EvGoPreempt      = 18 // goroutine is preempted [timestamp, stack]
 	EvGoSleep        = 19 // goroutine calls Sleep [timestamp, stack]
 	EvGoBlock        = 20 // goroutine blocks [timestamp, stack]
-	EvGoUnblock      = 21 // goroutine is unblocked [timestamp, goroutine id, stack]
+	EvGoUnblock      = 21 // goroutine is unblocked [timestamp, goroutine id, seq, stack]
 	EvGoBlockSend    = 22 // goroutine blocks on chan send [timestamp, stack]
 	EvGoBlockRecv    = 23 // goroutine blocks on chan recv [timestamp, stack]
 	EvGoBlockSelect  = 24 // goroutine blocks on select [timestamp, stack]
@@ -730,57 +873,66 @@ const (
 	EvGoBlockCond    = 26 // goroutine blocks on Cond [timestamp, stack]
 	EvGoBlockNet     = 27 // goroutine blocks on network [timestamp, stack]
 	EvGoSysCall      = 28 // syscall enter [timestamp, stack]
-	EvGoSysExit      = 29 // syscall exit [timestamp, goroutine id, real timestamp]
+	EvGoSysExit      = 29 // syscall exit [timestamp, goroutine id, seq, real timestamp]
 	EvGoSysBlock     = 30 // syscall blocks [timestamp]
-	EvGoWaiting      = 31 // denotes that goroutine is blocked when tracing starts [goroutine id]
-	EvGoInSyscall    = 32 // denotes that goroutine is in syscall when tracing starts [goroutine id]
-	EvHeapAlloc      = 33 // memstats.heap_alloc change [timestamp, heap_alloc]
+	EvGoWaiting      = 31 // denotes that goroutine is blocked when tracing starts [timestamp, goroutine id]
+	EvGoInSyscall    = 32 // denotes that goroutine is in syscall when tracing starts [timestamp, goroutine id]
+	EvHeapAlloc      = 33 // memstats.heap_live change [timestamp, heap_alloc]
 	EvNextGC         = 34 // memstats.next_gc change [timestamp, next_gc]
 	EvTimerGoroutine = 35 // denotes timer goroutine [timer goroutine id]
 	EvFutileWakeup   = 36 // denotes that the previous wakeup of this goroutine was futile [timestamp]
-	EvCount          = 37
+	EvString         = 37 // string dictionary entry [ID, length, string]
+	EvGoStartLocal   = 38 // goroutine starts running on the same P as the last event [timestamp, goroutine id]
+	EvGoUnblockLocal = 39 // goroutine is unblocked on the same P as the last event [timestamp, goroutine id, stack]
+	EvGoSysExitLocal = 40 // syscall exit on the same P as the last event [timestamp, goroutine id, real timestamp]
+	EvCount          = 41
 )
 
 var EventDescriptions = [EvCount]struct {
-	Name  string
-	Stack bool
-	Args  []string
+	Name       string
+	minVersion int
+	Stack      bool
+	Args       []string
 }{
-	EvNone:           {"None", false, []string{}},
-	EvBatch:          {"Batch", false, []string{"p", "seq", "ticks"}},
-	EvFrequency:      {"Frequency", false, []string{"freq", "unused"}},
-	EvStack:          {"Stack", false, []string{"id", "siz"}},
-	EvGomaxprocs:     {"Gomaxprocs", true, []string{"procs"}},
-	EvProcStart:      {"ProcStart", false, []string{"thread"}},
-	EvProcStop:       {"ProcStop", false, []string{}},
-	EvGCStart:        {"GCStart", true, []string{}},
-	EvGCDone:         {"GCDone", false, []string{}},
-	EvGCScanStart:    {"GCScanStart", false, []string{}},
-	EvGCScanDone:     {"GCScanDone", false, []string{}},
-	EvGCSweepStart:   {"GCSweepStart", true, []string{}},
-	EvGCSweepDone:    {"GCSweepDone", false, []string{}},
-	EvGoCreate:       {"GoCreate", true, []string{"g", "pc"}},
-	EvGoStart:        {"GoStart", false, []string{"g"}},
-	EvGoEnd:          {"GoEnd", false, []string{}},
-	EvGoStop:         {"GoStop", true, []string{}},
-	EvGoSched:        {"GoSched", true, []string{}},
-	EvGoPreempt:      {"GoPreempt", true, []string{}},
-	EvGoSleep:        {"GoSleep", true, []string{}},
-	EvGoBlock:        {"GoBlock", true, []string{}},
-	EvGoUnblock:      {"GoUnblock", true, []string{"g"}},
-	EvGoBlockSend:    {"GoBlockSend", true, []string{}},
-	EvGoBlockRecv:    {"GoBlockRecv", true, []string{}},
-	EvGoBlockSelect:  {"GoBlockSelect", true, []string{}},
-	EvGoBlockSync:    {"GoBlockSync", true, []string{}},
-	EvGoBlockCond:    {"GoBlockCond", true, []string{}},
-	EvGoBlockNet:     {"GoBlockNet", true, []string{}},
-	EvGoSysCall:      {"GoSysCall", true, []string{}},
-	EvGoSysExit:      {"GoSysExit", false, []string{"g", "seq", "ts"}},
-	EvGoSysBlock:     {"GoSysBlock", false, []string{}},
-	EvGoWaiting:      {"GoWaiting", false, []string{"g"}},
-	EvGoInSyscall:    {"GoInSyscall", false, []string{"g"}},
-	EvHeapAlloc:      {"HeapAlloc", false, []string{"mem"}},
-	EvNextGC:         {"NextGC", false, []string{"mem"}},
-	EvTimerGoroutine: {"TimerGoroutine", false, []string{"g", "unused"}},
-	EvFutileWakeup:   {"FutileWakeup", false, []string{}},
+	EvNone:           {"None", 1005, false, []string{}},
+	EvBatch:          {"Batch", 1005, false, []string{"p", "ticks"}}, // in 1.5 format it was {"p", "seq", "ticks"}
+	EvFrequency:      {"Frequency", 1005, false, []string{"freq"}},   // in 1.5 format it was {"freq", "unused"}
+	EvStack:          {"Stack", 1005, false, []string{"id", "siz"}},
+	EvGomaxprocs:     {"Gomaxprocs", 1005, true, []string{"procs"}},
+	EvProcStart:      {"ProcStart", 1005, false, []string{"thread"}},
+	EvProcStop:       {"ProcStop", 1005, false, []string{}},
+	EvGCStart:        {"GCStart", 1005, true, []string{"seq"}}, // in 1.5 format it was {}
+	EvGCDone:         {"GCDone", 1005, false, []string{}},
+	EvGCScanStart:    {"GCScanStart", 1005, false, []string{}},
+	EvGCScanDone:     {"GCScanDone", 1005, false, []string{}},
+	EvGCSweepStart:   {"GCSweepStart", 1005, true, []string{}},
+	EvGCSweepDone:    {"GCSweepDone", 1005, false, []string{}},
+	EvGoCreate:       {"GoCreate", 1005, true, []string{"g", "stack"}},
+	EvGoStart:        {"GoStart", 1005, false, []string{"g", "seq"}}, // in 1.5 format it was {"g"}
+	EvGoEnd:          {"GoEnd", 1005, false, []string{}},
+	EvGoStop:         {"GoStop", 1005, true, []string{}},
+	EvGoSched:        {"GoSched", 1005, true, []string{}},
+	EvGoPreempt:      {"GoPreempt", 1005, true, []string{}},
+	EvGoSleep:        {"GoSleep", 1005, true, []string{}},
+	EvGoBlock:        {"GoBlock", 1005, true, []string{}},
+	EvGoUnblock:      {"GoUnblock", 1005, true, []string{"g", "seq"}}, // in 1.5 format it was {"g"}
+	EvGoBlockSend:    {"GoBlockSend", 1005, true, []string{}},
+	EvGoBlockRecv:    {"GoBlockRecv", 1005, true, []string{}},
+	EvGoBlockSelect:  {"GoBlockSelect", 1005, true, []string{}},
+	EvGoBlockSync:    {"GoBlockSync", 1005, true, []string{}},
+	EvGoBlockCond:    {"GoBlockCond", 1005, true, []string{}},
+	EvGoBlockNet:     {"GoBlockNet", 1005, true, []string{}},
+	EvGoSysCall:      {"GoSysCall", 1005, true, []string{}},
+	EvGoSysExit:      {"GoSysExit", 1005, false, []string{"g", "seq", "ts"}},
+	EvGoSysBlock:     {"GoSysBlock", 1005, false, []string{}},
+	EvGoWaiting:      {"GoWaiting", 1005, false, []string{"g"}},
+	EvGoInSyscall:    {"GoInSyscall", 1005, false, []string{"g"}},
+	EvHeapAlloc:      {"HeapAlloc", 1005, false, []string{"mem"}},
+	EvNextGC:         {"NextGC", 1005, false, []string{"mem"}},
+	EvTimerGoroutine: {"TimerGoroutine", 1005, false, []string{"g"}}, // in 1.5 format it was {"g", "unused"}
+	EvFutileWakeup:   {"FutileWakeup", 1005, false, []string{}},
+	EvString:         {"String", 1007, false, []string{}},
+	EvGoStartLocal:   {"GoStartLocal", 1007, false, []string{"g"}},
+	EvGoUnblockLocal: {"GoUnblockLocal", 1007, true, []string{"g"}},
+	EvGoSysExitLocal: {"GoSysExitLocal", 1007, false, []string{"g", "ts"}},
 }
diff --git a/libgo/go/internal/trace/parser_test.go b/libgo/go/internal/trace/parser_test.go
index fecefc4053a..daad3e3ad7e 100644
--- a/libgo/go/internal/trace/parser_test.go
+++ b/libgo/go/internal/trace/parser_test.go
@@ -5,6 +5,9 @@
 package trace
 
 import (
+	"bytes"
+	"io/ioutil"
+	"path/filepath"
 	"strings"
 	"testing"
 )
@@ -22,9 +25,117 @@ func TestCorruptedInputs(t *testing.T) {
 		"go 1.5 trace\x00\x00\x00\x00\xc3\x0200",
 	}
 	for _, data := range tests {
-		events, err := Parse(strings.NewReader(data))
+		events, err := Parse(strings.NewReader(data), "")
 		if err == nil || events != nil {
-			t.Fatalf("no error on input: %q\n", data)
+			t.Fatalf("no error on input: %q", data)
 		}
 	}
 }
+
+func TestParseCanned(t *testing.T) {
+	files, err := ioutil.ReadDir("./testdata")
+	if err != nil {
+		t.Fatalf("failed to read ./testdata: %v", err)
+	}
+	for _, f := range files {
+		data, err := ioutil.ReadFile(filepath.Join("./testdata", f.Name()))
+		if err != nil {
+			t.Fatalf("failed to read input file: %v", err)
+		}
+		// Instead of Parse that requires a proper binary name for old traces,
+		// we use 'parse' that omits symbol lookup if an empty string is given.
+		_, _, err = parse(bytes.NewReader(data), "")
+		switch {
+		case strings.HasSuffix(f.Name(), "_good"):
+			if err != nil {
+				t.Errorf("failed to parse good trace %v: %v", f.Name(), err)
+			}
+		case strings.HasSuffix(f.Name(), "_unordered"):
+			if err != ErrTimeOrder {
+				t.Errorf("unordered trace is not detected %v: %v", f.Name(), err)
+			}
+		default:
+			t.Errorf("unknown input file suffix: %v", f.Name())
+		}
+	}
+}
+
+func TestParseVersion(t *testing.T) {
+	tests := map[string]int{
+		"go 1.5 trace\x00\x00\x00\x00": 1005,
+		"go 1.7 trace\x00\x00\x00\x00": 1007,
+		"go 1.10 trace\x00\x00\x00":    1010,
+		"go 1.25 trace\x00\x00\x00":    1025,
+		"go 1.234 trace\x00\x00":       1234,
+		"go 1.2345 trace\x00":          -1,
+		"go 0.0 trace\x00\x00\x00\x00": -1,
+		"go a.b trace\x00\x00\x00\x00": -1,
+	}
+	for header, ver := range tests {
+		ver1, err := parseHeader([]byte(header))
+		if ver == -1 {
+			if err == nil {
+				t.Fatalf("no error on input: %q, version %v", header, ver1)
+			}
+		} else {
+			if err != nil {
+				t.Fatalf("failed to parse: %q (%v)", header, err)
+			}
+			if ver != ver1 {
+				t.Fatalf("wrong version: %v, want %v, input: %q", ver1, ver, header)
+			}
+		}
+	}
+}
+
+func TestTimestampOverflow(t *testing.T) {
+	// Test that parser correctly handles large timestamps (long tracing).
+	w := newWriter()
+	w.emit(EvBatch, 0, 0)
+	w.emit(EvFrequency, 1e9)
+	for ts := uint64(1); ts < 1e16; ts *= 2 {
+		w.emit(EvGoCreate, ts, ts, 0, 0)
+	}
+	if _, err := Parse(w, ""); err != nil {
+		t.Fatalf("failed to parse: %v", err)
+	}
+}
+
+type writer struct {
+	bytes.Buffer
+}
+
+func newWriter() *writer {
+	w := new(writer)
+	w.Write([]byte("go 1.7 trace\x00\x00\x00\x00"))
+	return w
+}
+
+func (w *writer) emit(typ byte, args ...uint64) {
+	nargs := byte(len(args)) - 1
+	if nargs > 3 {
+		nargs = 3
+	}
+	buf := []byte{typ | nargs<<6}
+	if nargs == 3 {
+		buf = append(buf, 0)
+	}
+	for _, a := range args {
+		buf = appendVarint(buf, a)
+	}
+	if nargs == 3 {
+		buf[1] = byte(len(buf) - 2)
+	}
+	n, err := w.Write(buf)
+	if n != len(buf) || err != nil {
+		panic("failed to write")
+	}
+}
+
+func appendVarint(buf []byte, v uint64) []byte {
+	for ; v >= 0x80; v >>= 7 {
+		buf = append(buf, 0x80|byte(v))
+	}
+	buf = append(buf, byte(v))
+	return buf
+}
diff --git a/libgo/go/internal/trace/testdata/http_1_5_good b/libgo/go/internal/trace/testdata/http_1_5_good
new file mode 100644
index 00000000000..0736cae6741
--- /dev/null
+++ b/libgo/go/internal/trace/testdata/http_1_5_good
diff --git a/libgo/go/internal/trace/testdata/stress_1_5_good b/libgo/go/internal/trace/testdata/stress_1_5_good
new file mode 100644
index 00000000000..c5055ebd19f
--- /dev/null
+++ b/libgo/go/internal/trace/testdata/stress_1_5_good
diff --git a/libgo/go/internal/trace/testdata/stress_1_5_unordered b/libgo/go/internal/trace/testdata/stress_1_5_unordered
new file mode 100644
index 00000000000..11f7d745ca9
--- /dev/null
+++ b/libgo/go/internal/trace/testdata/stress_1_5_unordered
diff --git a/libgo/go/internal/trace/testdata/stress_start_stop_1_5_good b/libgo/go/internal/trace/testdata/stress_start_stop_1_5_good
new file mode 100644
index 00000000000..72a887b8444
--- /dev/null
+++ b/libgo/go/internal/trace/testdata/stress_start_stop_1_5_good
diff --git a/libgo/go/io/example_test.go b/libgo/go/io/example_test.go
index 412dfb3b921..bf16de8fe23 100644
--- a/libgo/go/io/example_test.go
+++ b/libgo/go/io/example_test.go
@@ -189,7 +189,7 @@ func ExampleSectionReader_Seek() {
 	r := strings.NewReader("some io.Reader stream to be read\n")
 	s := io.NewSectionReader(r, 5, 16)
 
-	if _, err := s.Seek(10, 0); err != nil {
+	if _, err := s.Seek(10, io.SeekStart); err != nil {
 		log.Fatal(err)
 	}
 
diff --git a/libgo/go/io/io.go b/libgo/go/io/io.go
index 8e7855c665f..19d0ae5addb 100644
--- a/libgo/go/io/io.go
+++ b/libgo/go/io/io.go
@@ -16,6 +16,13 @@ import (
 	"errors"
 )
 
+// Seek whence values.
+const (
+	SeekStart   = 0 // seek relative to the origin of the file
+	SeekCurrent = 1 // seek relative to the current offset
+	SeekEnd     = 2 // seek relative to the end
+)
+
 // ErrShortWrite means that a write accepted fewer bytes than requested
 // but failed to return an explicit error.
 var ErrShortWrite = errors.New("short write")
@@ -41,23 +48,23 @@ var ErrNoProgress = errors.New("multiple Read calls return no data or error")
 
 // Reader is the interface that wraps the basic Read method.
 //
-// Read reads up to len(p) bytes into p.  It returns the number of bytes
-// read (0 <= n <= len(p)) and any error encountered.  Even if Read
+// Read reads up to len(p) bytes into p. It returns the number of bytes
+// read (0 <= n <= len(p)) and any error encountered. Even if Read
 // returns n < len(p), it may use all of p as scratch space during the call.
 // If some data is available but not len(p) bytes, Read conventionally
 // returns what is available instead of waiting for more.
 //
 // When Read encounters an error or end-of-file condition after
 // successfully reading n > 0 bytes, it returns the number of
-// bytes read.  It may return the (non-nil) error from the same call
+// bytes read. It may return the (non-nil) error from the same call
 // or return the error (and n == 0) from a subsequent call.
 // An instance of this general case is that a Reader returning
 // a non-zero number of bytes at the end of the input stream may
-// return either err == EOF or err == nil.  The next Read should
+// return either err == EOF or err == nil. The next Read should
 // return 0, EOF.
 //
 // Callers should always process the n > 0 bytes returned before
-// considering the error err.  Doing so correctly handles I/O errors
+// considering the error err. Doing so correctly handles I/O errors
 // that happen after reading some bytes and also both of the
 // allowed EOF behaviors.
 //
@@ -95,10 +102,12 @@ type Closer interface {
 // Seeker is the interface that wraps the basic Seek method.
 //
 // Seek sets the offset for the next Read or Write to offset,
-// interpreted according to whence: 0 means relative to the start of
-// the file, 1 means relative to the current offset, and 2 means
-// relative to the end. Seek returns the new offset relative to the
-// start of the file and an error, if any.
+// interpreted according to whence:
+// SeekStart means relative to the start of the file,
+// SeekCurrent means relative to the current offset, and
+// SeekEnd means relative to the end.
+// Seek returns the new offset relative to the start of the
+// file and an error, if any.
 //
 // Seeking to an offset before the start of the file is an error.
 // Seeking to any positive offset is legal, but the behavior of subsequent
@@ -176,15 +185,15 @@ type WriterTo interface {
 // ReaderAt is the interface that wraps the basic ReadAt method.
 //
 // ReadAt reads len(p) bytes into p starting at offset off in the
-// underlying input source.  It returns the number of bytes
+// underlying input source. It returns the number of bytes
 // read (0 <= n <= len(p)) and any error encountered.
 //
 // When ReadAt returns n < len(p), it returns a non-nil error
-// explaining why more bytes were not returned.  In this respect,
+// explaining why more bytes were not returned. In this respect,
 // ReadAt is stricter than Read.
 //
 // Even if ReadAt returns n < len(p), it may use all of p as scratch
-// space during the call.  If some data is available but not len(p) bytes,
+// space during the call. If some data is available but not len(p) bytes,
 // ReadAt blocks until either all the data is available or an error occurs.
 // In this respect ReadAt is different from Read.
 //
@@ -206,7 +215,7 @@ type ReaderAt interface {
 // WriterAt is the interface that wraps the basic WriteAt method.
 //
 // WriteAt writes len(p) bytes from p to the underlying data stream
-// at offset off.  It returns the number of bytes written from p (0 <= n <= len(p))
+// at offset off. It returns the number of bytes written from p (0 <= n <= len(p))
 // and any error encountered that caused the write to stop early.
 // WriteAt must return a non-nil error if it returns n < len(p).
 //
@@ -226,7 +235,7 @@ type WriterAt interface {
 //
 // ReadByte reads and returns the next byte from the input.
 type ByteReader interface {
-	ReadByte() (c byte, err error)
+	ReadByte() (byte, error)
 }
 
 // ByteScanner is the interface that adds the UnreadByte method to the
@@ -274,6 +283,7 @@ type stringWriter interface {
 
 // WriteString writes the contents of the string s to w, which accepts a slice of bytes.
 // If w implements a WriteString method, it is invoked directly.
+// Otherwise, w.Write is called exactly once.
 func WriteString(w Writer, s string) (n int, err error) {
 	if sw, ok := w.(stringWriter); ok {
 		return sw.WriteString(s)
@@ -335,7 +345,7 @@ func CopyN(dst Writer, src Reader, n int64) (written int64, err error) {
 }
 
 // Copy copies from src to dst until either EOF is reached
-// on src or an error occurs.  It returns the number of bytes
+// on src or an error occurs. It returns the number of bytes
 // copied and the first error encountered while copying, if any.
 //
 // A successful Copy returns err == nil, not err == EOF.
@@ -462,11 +472,11 @@ func (s *SectionReader) Seek(offset int64, whence int) (int64, error) {
 	switch whence {
 	default:
 		return 0, errWhence
-	case 0:
+	case SeekStart:
 		offset += s.base
-	case 1:
+	case SeekCurrent:
 		offset += s.off
-	case 2:
+	case SeekEnd:
 		offset += s.limit
 	}
 	if offset < s.base {
@@ -497,7 +507,7 @@ func (s *SectionReader) Size() int64 { return s.limit - s.base }
 
 // TeeReader returns a Reader that writes to w what it reads from r.
 // All reads from r performed through it are matched with
-// corresponding writes to w.  There is no internal buffering -
+// corresponding writes to w. There is no internal buffering -
 // the write must complete before the read completes.
 // Any error encountered while writing is reported as a read error.
 func TeeReader(r Reader, w Writer) Reader {
diff --git a/libgo/go/io/io_test.go b/libgo/go/io/io_test.go
index e892574b0b5..877e8392e27 100644
--- a/libgo/go/io/io_test.go
+++ b/libgo/go/io/io_test.go
@@ -347,7 +347,7 @@ func TestSectionReader_Seek(t *testing.T) {
 	br := bytes.NewReader([]byte("foo"))
 	sr := NewSectionReader(br, 0, int64(len("foo")))
 
-	for whence := 0; whence <= 2; whence++ {
+	for _, whence := range []int{SeekStart, SeekCurrent, SeekEnd} {
 		for offset := int64(-3); offset <= 4; offset++ {
 			brOff, brErr := br.Seek(offset, whence)
 			srOff, srErr := sr.Seek(offset, whence)
@@ -359,7 +359,7 @@ func TestSectionReader_Seek(t *testing.T) {
 	}
 
 	// And verify we can just seek past the end and get an EOF
-	got, err := sr.Seek(100, 0)
+	got, err := sr.Seek(100, SeekStart)
 	if err != nil || got != 100 {
 		t.Errorf("Seek = %v, %v; want 100, nil", got, err)
 	}
diff --git a/libgo/go/io/ioutil/ioutil.go b/libgo/go/io/ioutil/ioutil.go
index e90a33f99b0..8ecbb2de764 100644
--- a/libgo/go/io/ioutil/ioutil.go
+++ b/libgo/go/io/ioutil/ioutil.go
@@ -63,8 +63,8 @@ func ReadFile(filename string) ([]byte, error) {
 		}
 	}
 	// As initial capacity for readAll, use n + a little extra in case Size is zero,
-	// and to avoid another allocation after Read has filled the buffer.  The readAll
-	// call will read into its allocated internal buffer cheaply.  If the size was
+	// and to avoid another allocation after Read has filled the buffer. The readAll
+	// call will read into its allocated internal buffer cheaply. If the size was
 	// wrong, we'll either waste some space off the end or reallocate as needed, but
 	// in the overwhelmingly common case we'll get it just right.
 	return readAll(f, n+bytes.MinRead)
diff --git a/libgo/go/io/ioutil/tempfile.go b/libgo/go/io/ioutil/tempfile.go
index 61d4a7ad37d..42718cc73d3 100644
--- a/libgo/go/io/ioutil/tempfile.go
+++ b/libgo/go/io/ioutil/tempfile.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -41,8 +41,8 @@ func nextSuffix() string {
 // If dir is the empty string, TempFile uses the default directory
 // for temporary files (see os.TempDir).
 // Multiple programs calling TempFile simultaneously
-// will not choose the same file.  The caller can use f.Name()
-// to find the pathname of the file.  It is the caller's responsibility
+// will not choose the same file. The caller can use f.Name()
+// to find the pathname of the file. It is the caller's responsibility
 // to remove the file when no longer needed.
 func TempFile(dir, prefix string) (f *os.File, err error) {
 	if dir == "" {
@@ -68,10 +68,10 @@ func TempFile(dir, prefix string) (f *os.File, err error) {
 
 // TempDir creates a new temporary directory in the directory dir
 // with a name beginning with prefix and returns the path of the
-// new directory.  If dir is the empty string, TempDir uses the
+// new directory. If dir is the empty string, TempDir uses the
 // default directory for temporary files (see os.TempDir).
 // Multiple programs calling TempDir simultaneously
-// will not choose the same directory.  It is the caller's responsibility
+// will not choose the same directory. It is the caller's responsibility
 // to remove the directory when no longer needed.
 func TempDir(dir, prefix string) (name string, err error) {
 	if dir == "" {
diff --git a/libgo/go/io/multi.go b/libgo/go/io/multi.go
index 16860aa361f..ed05cac9e72 100644
--- a/libgo/go/io/multi.go
+++ b/libgo/go/io/multi.go
@@ -10,6 +10,13 @@ type multiReader struct {
 
 func (mr *multiReader) Read(p []byte) (n int, err error) {
 	for len(mr.readers) > 0 {
+		// Optimization to flatten nested multiReaders (Issue 13558)
+		if len(mr.readers) == 1 {
+			if r, ok := mr.readers[0].(*multiReader); ok {
+				mr.readers = r.readers
+				continue
+			}
+		}
 		n, err = mr.readers[0].Read(p)
 		if n > 0 || err != EOF {
 			if err == EOF {
@@ -25,7 +32,7 @@ func (mr *multiReader) Read(p []byte) (n int, err error) {
 }
 
 // MultiReader returns a Reader that's the logical concatenation of
-// the provided input readers.  They're read sequentially.  Once all
+// the provided input readers. They're read sequentially. Once all
 // inputs have returned EOF, Read will return EOF.  If any of the readers
 // return a non-nil, non-EOF error, Read will return that error.
 func MultiReader(readers ...Reader) Reader {
diff --git a/libgo/go/io/multi_test.go b/libgo/go/io/multi_test.go
index c5d1b9530ea..a434453f6b0 100644
--- a/libgo/go/io/multi_test.go
+++ b/libgo/go/io/multi_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,9 +7,11 @@ package io_test
 import (
 	"bytes"
 	"crypto/sha1"
+	"errors"
 	"fmt"
 	. "io"
 	"io/ioutil"
+	"runtime"
 	"strings"
 	"testing"
 )
@@ -165,3 +167,33 @@ func TestMultiWriterCopy(t *testing.T) {
 		t.Errorf("buf.String() = %q, want %q", buf.String(), "hello world")
 	}
 }
+
+// readerFunc is an io.Reader implemented by the underlying func.
+type readerFunc func(p []byte) (int, error)
+
+func (f readerFunc) Read(p []byte) (int, error) {
+	return f(p)
+}
+
+// Test that MultiReader properly flattens chained multiReaders when Read is called
+func TestMultiReaderFlatten(t *testing.T) {
+	pc := make([]uintptr, 1000) // 1000 should fit the full stack
+	var myDepth = runtime.Callers(0, pc)
+	var readDepth int // will contain the depth from which fakeReader.Read was called
+	var r Reader = MultiReader(readerFunc(func(p []byte) (int, error) {
+		readDepth = runtime.Callers(1, pc)
+		return 0, errors.New("irrelevant")
+	}))
+
+	// chain a bunch of multiReaders
+	for i := 0; i < 100; i++ {
+		r = MultiReader(r)
+	}
+
+	r.Read(nil) // don't care about errors, just want to check the call-depth for Read
+
+	if readDepth != myDepth+2 { // 2 should be multiReader.Read and fakeReader.Read
+		t.Errorf("multiReader did not flatten chained multiReaders: expected readDepth %d, got %d",
+			myDepth+2, readDepth)
+	}
+}
diff --git a/libgo/go/io/pipe.go b/libgo/go/io/pipe.go
index 179515e78d3..7e98cd2eb78 100644
--- a/libgo/go/io/pipe.go
+++ b/libgo/go/io/pipe.go
@@ -15,11 +15,6 @@ import (
 // ErrClosedPipe is the error used for read or write operations on a closed pipe.
 var ErrClosedPipe = errors.New("io: read/write on closed pipe")
 
-type pipeResult struct {
-	n   int
-	err error
-}
-
 // A pipe is the shared pipe structure underlying PipeReader and PipeWriter.
 type pipe struct {
 	rl    sync.Mutex // gates readers one at a time
diff --git a/libgo/go/log/log.go b/libgo/go/log/log.go
index 4cfe5503006..26cdb532dfc 100644
--- a/libgo/go/log/log.go
+++ b/libgo/go/log/log.go
@@ -42,8 +42,8 @@ const (
 )
 
 // A Logger represents an active logging object that generates lines of
-// output to an io.Writer.  Each logging operation makes a single call to
-// the Writer's Write method.  A Logger can be used simultaneously from
+// output to an io.Writer. Each logging operation makes a single call to
+// the Writer's Write method. A Logger can be used simultaneously from
 // multiple goroutines; it guarantees to serialize access to the Writer.
 type Logger struct {
 	mu     sync.Mutex // ensures atomic writes; protects the following fields
@@ -53,7 +53,7 @@ type Logger struct {
 	buf    []byte     // for accumulating text to write
 }
 
-// New creates a new Logger.   The out variable sets the
+// New creates a new Logger. The out variable sets the
 // destination to which log data will be written.
 // The prefix appears at the beginning of each generated log line.
 // The flag argument defines the logging properties.
@@ -134,10 +134,10 @@ func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {
 	}
 }
 
-// Output writes the output for a logging event.  The string s contains
+// Output writes the output for a logging event. The string s contains
 // the text to print after the prefix specified by the flags of the
-// Logger.  A newline is appended if the last character of s is not
-// already a newline.  Calldepth is used to recover the PC and is
+// Logger. A newline is appended if the last character of s is not
+// already a newline. Calldepth is used to recover the PC and is
 // provided for generality, although at the moment on all pre-defined
 // paths it will be 2.
 func (l *Logger) Output(calldepth int, s string) error {
@@ -334,10 +334,10 @@ func Panicln(v ...interface{}) {
 	panic(s)
 }
 
-// Output writes the output for a logging event.  The string s contains
+// Output writes the output for a logging event. The string s contains
 // the text to print after the prefix specified by the flags of the
-// Logger.  A newline is appended if the last character of s is not
-// already a newline.  Calldepth is the count of the number of
+// Logger. A newline is appended if the last character of s is not
+// already a newline. Calldepth is the count of the number of
 // frames to skip when computing the file name and line number
 // if Llongfile or Lshortfile is set; a value of 1 will print the details
 // for the caller of Output.
diff --git a/libgo/go/log/syslog/syslog.go b/libgo/go/log/syslog/syslog.go
index 4bf447626f2..9e888dd1d9d 100644
--- a/libgo/go/log/syslog/syslog.go
+++ b/libgo/go/log/syslog/syslog.go
@@ -85,8 +85,8 @@ type Writer struct {
 }
 
 // This interface and the separate syslog_unix.go file exist for
-// Solaris support as implemented by gccgo.  On Solaris you can not
-// simply open a TCP connection to the syslog daemon.  The gccgo
+// Solaris support as implemented by gccgo. On Solaris you cannot
+// simply open a TCP connection to the syslog daemon. The gccgo
 // sources have a syslog_solaris.go file that implements unixSyslog to
 // return a type that satisfies this interface and simply calls the C
 // library syslog function.
@@ -100,15 +100,15 @@ type netConn struct {
 	conn  net.Conn
 }
 
-// New establishes a new connection to the system log daemon.  Each
+// New establishes a new connection to the system log daemon. Each
 // write to the returned writer sends a log message with the given
 // priority and prefix.
-func New(priority Priority, tag string) (w *Writer, err error) {
+func New(priority Priority, tag string) (*Writer, error) {
 	return Dial("", "", priority, tag)
 }
 
 // Dial establishes a connection to a log daemon by connecting to
-// address raddr on the specified network.  Each write to the returned
+// address raddr on the specified network. Each write to the returned
 // writer sends a log message with the given facility, severity and
 // tag.
 // If network is empty, Dial will connect to the local syslog server.
@@ -187,57 +187,57 @@ func (w *Writer) Close() error {
 
 // Emerg logs a message with severity LOG_EMERG, ignoring the severity
 // passed to New.
-func (w *Writer) Emerg(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_EMERG, m)
+func (w *Writer) Emerg(m string) error {
+	_, err := w.writeAndRetry(LOG_EMERG, m)
 	return err
 }
 
 // Alert logs a message with severity LOG_ALERT, ignoring the severity
 // passed to New.
-func (w *Writer) Alert(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_ALERT, m)
+func (w *Writer) Alert(m string) error {
+	_, err := w.writeAndRetry(LOG_ALERT, m)
 	return err
 }
 
 // Crit logs a message with severity LOG_CRIT, ignoring the severity
 // passed to New.
-func (w *Writer) Crit(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_CRIT, m)
+func (w *Writer) Crit(m string) error {
+	_, err := w.writeAndRetry(LOG_CRIT, m)
 	return err
 }
 
 // Err logs a message with severity LOG_ERR, ignoring the severity
 // passed to New.
-func (w *Writer) Err(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_ERR, m)
+func (w *Writer) Err(m string) error {
+	_, err := w.writeAndRetry(LOG_ERR, m)
 	return err
 }
 
 // Warning logs a message with severity LOG_WARNING, ignoring the
 // severity passed to New.
-func (w *Writer) Warning(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_WARNING, m)
+func (w *Writer) Warning(m string) error {
+	_, err := w.writeAndRetry(LOG_WARNING, m)
 	return err
 }
 
 // Notice logs a message with severity LOG_NOTICE, ignoring the
 // severity passed to New.
-func (w *Writer) Notice(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_NOTICE, m)
+func (w *Writer) Notice(m string) error {
+	_, err := w.writeAndRetry(LOG_NOTICE, m)
 	return err
 }
 
 // Info logs a message with severity LOG_INFO, ignoring the severity
 // passed to New.
-func (w *Writer) Info(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_INFO, m)
+func (w *Writer) Info(m string) error {
+	_, err := w.writeAndRetry(LOG_INFO, m)
 	return err
 }
 
 // Debug logs a message with severity LOG_DEBUG, ignoring the severity
 // passed to New.
-func (w *Writer) Debug(m string) (err error) {
-	_, err = w.writeAndRetry(LOG_DEBUG, m)
+func (w *Writer) Debug(m string) error {
+	_, err := w.writeAndRetry(LOG_DEBUG, m)
 	return err
 }
 
diff --git a/libgo/go/math/acosh.go b/libgo/go/math/acosh.go
index e394008b078..dce21b23507 100644
--- a/libgo/go/math/acosh.go
+++ b/libgo/go/math/acosh.go
@@ -6,7 +6,7 @@ package math
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/e_acosh.c
-// and came with this notice.  The go code is a simplified
+// and came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/all_test.go b/libgo/go/math/all_test.go
index 968a7b18372..d9ea1fdb51a 100644
--- a/libgo/go/math/all_test.go
+++ b/libgo/go/math/all_test.go
@@ -1225,12 +1225,6 @@ var hypotSC = []float64{
 	NaN(),
 }
 
-var vfilogbSC = []float64{
-	Inf(-1),
-	0,
-	Inf(1),
-	NaN(),
-}
 var ilogbSC = []int{
 	MaxInt32,
 	MinInt32,
@@ -1756,7 +1750,6 @@ func tolerance(a, b, e float64) bool {
 	}
 	return d < e
 }
-func kindaclose(a, b float64) bool { return tolerance(a, b, 1e-8) }
 func close(a, b float64) bool      { return tolerance(a, b, 1e-14) }
 func veryclose(a, b float64) bool  { return tolerance(a, b, 4e-16) }
 func soclose(a, b, e float64) bool { return tolerance(a, b, e) }
diff --git a/libgo/go/math/asinh.go b/libgo/go/math/asinh.go
index ff2de0215f5..3b793b0ceaa 100644
--- a/libgo/go/math/asinh.go
+++ b/libgo/go/math/asinh.go
@@ -6,7 +6,7 @@ package math
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/s_asinh.c
-// and came with this notice.  The go code is a simplified
+// and came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/atanh.go b/libgo/go/math/atanh.go
index 113d5c103c0..d59a8474fc0 100644
--- a/libgo/go/math/atanh.go
+++ b/libgo/go/math/atanh.go
@@ -6,7 +6,7 @@ package math
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/e_atanh.c
-// and came with this notice.  The go code is a simplified
+// and came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/big/arith_decl.go b/libgo/go/math/big/arith_decl.go
index 1707aa4e209..5433b6d61d4 100644
--- a/libgo/go/math/big/arith_decl.go
+++ b/libgo/go/math/big/arith_decl.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/math/big/arith_decl_pure.go b/libgo/go/math/big/arith_decl_pure.go
index e760a3816b3..21775ddf3e3 100644
--- a/libgo/go/math/big/arith_decl_pure.go
+++ b/libgo/go/math/big/arith_decl_pure.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/math/big/arith_test.go b/libgo/go/math/big/arith_test.go
index f46a494f175..75862b4951f 100644
--- a/libgo/go/math/big/arith_test.go
+++ b/libgo/go/math/big/arith_test.go
@@ -5,6 +5,7 @@
 package big
 
 import (
+	"fmt"
 	"math/rand"
 	"testing"
 )
@@ -118,28 +119,22 @@ func rndV(n int) []Word {
 	return v
 }
 
-func benchmarkFunVV(b *testing.B, f funVV, n int) {
-	x := rndV(n)
-	y := rndV(n)
-	z := make([]Word, n)
-	b.SetBytes(int64(n * _W))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		f(z, x, y)
+var benchSizes = []int{1, 2, 3, 4, 5, 1e1, 1e2, 1e3, 1e4, 1e5}
+
+func BenchmarkAddVV(b *testing.B) {
+	for _, n := range benchSizes {
+		x := rndV(n)
+		y := rndV(n)
+		z := make([]Word, n)
+		b.Run(fmt.Sprint(n), func(b *testing.B) {
+			b.SetBytes(int64(n * _W))
+			for i := 0; i < b.N; i++ {
+				addVV(z, x, y)
+			}
+		})
 	}
 }
 
-func BenchmarkAddVV_1(b *testing.B)   { benchmarkFunVV(b, addVV, 1) }
-func BenchmarkAddVV_2(b *testing.B)   { benchmarkFunVV(b, addVV, 2) }
-func BenchmarkAddVV_3(b *testing.B)   { benchmarkFunVV(b, addVV, 3) }
-func BenchmarkAddVV_4(b *testing.B)   { benchmarkFunVV(b, addVV, 4) }
-func BenchmarkAddVV_5(b *testing.B)   { benchmarkFunVV(b, addVV, 5) }
-func BenchmarkAddVV_1e1(b *testing.B) { benchmarkFunVV(b, addVV, 1e1) }
-func BenchmarkAddVV_1e2(b *testing.B) { benchmarkFunVV(b, addVV, 1e2) }
-func BenchmarkAddVV_1e3(b *testing.B) { benchmarkFunVV(b, addVV, 1e3) }
-func BenchmarkAddVV_1e4(b *testing.B) { benchmarkFunVV(b, addVV, 1e4) }
-func BenchmarkAddVV_1e5(b *testing.B) { benchmarkFunVV(b, addVV, 1e5) }
-
 type funVW func(z, x []Word, y Word) (c Word)
 type argVW struct {
 	z, x nat
@@ -158,21 +153,6 @@ var sumVW = []argVW{
 	{nat{585}, nat{314}, 271, 0},
 }
 
-var prodVW = []argVW{
-	{},
-	{nat{0}, nat{0}, 0, 0},
-	{nat{0}, nat{_M}, 0, 0},
-	{nat{0}, nat{0}, _M, 0},
-	{nat{1}, nat{1}, 1, 0},
-	{nat{22793}, nat{991}, 23, 0},
-	{nat{0, 0, 0, 22793}, nat{0, 0, 0, 991}, 23, 0},
-	{nat{0, 0, 0, 0}, nat{7893475, 7395495, 798547395, 68943}, 0, 0},
-	{nat{0, 0, 0, 0}, nat{0, 0, 0, 0}, 894375984, 0},
-	{nat{_M << 1 & _M}, nat{_M}, 1 << 1, _M >> (_W - 1)},
-	{nat{_M << 7 & _M}, nat{_M}, 1 << 7, _M >> (_W - 7)},
-	{nat{_M << 7 & _M, _M, _M, _M}, nat{_M, _M, _M, _M}, 1 << 7, _M >> (_W - 7)},
-}
-
 var lshVW = []argVW{
 	{},
 	{nat{0}, nat{0}, 0, 0},
@@ -251,28 +231,20 @@ func TestFunVW(t *testing.T) {
 	}
 }
 
-func benchmarkFunVW(b *testing.B, f funVW, n int) {
-	x := rndV(n)
-	y := rndW()
-	z := make([]Word, n)
-	b.SetBytes(int64(n * _S))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		f(z, x, y)
+func BenchmarkAddVW(b *testing.B) {
+	for _, n := range benchSizes {
+		x := rndV(n)
+		y := rndW()
+		z := make([]Word, n)
+		b.Run(fmt.Sprint(n), func(b *testing.B) {
+			b.SetBytes(int64(n * _S))
+			for i := 0; i < b.N; i++ {
+				addVW(z, x, y)
+			}
+		})
 	}
 }
 
-func BenchmarkAddVW_1(b *testing.B)   { benchmarkFunVW(b, addVW, 1) }
-func BenchmarkAddVW_2(b *testing.B)   { benchmarkFunVW(b, addVW, 2) }
-func BenchmarkAddVW_3(b *testing.B)   { benchmarkFunVW(b, addVW, 3) }
-func BenchmarkAddVW_4(b *testing.B)   { benchmarkFunVW(b, addVW, 4) }
-func BenchmarkAddVW_5(b *testing.B)   { benchmarkFunVW(b, addVW, 5) }
-func BenchmarkAddVW_1e1(b *testing.B) { benchmarkFunVW(b, addVW, 1e1) }
-func BenchmarkAddVW_1e2(b *testing.B) { benchmarkFunVW(b, addVW, 1e2) }
-func BenchmarkAddVW_1e3(b *testing.B) { benchmarkFunVW(b, addVW, 1e3) }
-func BenchmarkAddVW_1e4(b *testing.B) { benchmarkFunVW(b, addVW, 1e4) }
-func BenchmarkAddVW_1e5(b *testing.B) { benchmarkFunVW(b, addVW, 1e5) }
-
 type funVWW func(z, x []Word, y, r Word) (c Word)
 type argVWW struct {
 	z, x nat
@@ -397,28 +369,20 @@ func TestMulAddWWW(t *testing.T) {
 	}
 }
 
-func benchmarkAddMulVVW(b *testing.B, n int) {
-	x := rndV(n)
-	y := rndW()
-	z := make([]Word, n)
-	b.SetBytes(int64(n * _W))
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		addMulVVW(z, x, y)
+func BenchmarkAddMulVVW(b *testing.B) {
+	for _, n := range benchSizes {
+		x := rndV(n)
+		y := rndW()
+		z := make([]Word, n)
+		b.Run(fmt.Sprint(n), func(b *testing.B) {
+			b.SetBytes(int64(n * _W))
+			for i := 0; i < b.N; i++ {
+				addMulVVW(z, x, y)
+			}
+		})
 	}
 }
 
-func BenchmarkAddMulVVW_1(b *testing.B)   { benchmarkAddMulVVW(b, 1) }
-func BenchmarkAddMulVVW_2(b *testing.B)   { benchmarkAddMulVVW(b, 2) }
-func BenchmarkAddMulVVW_3(b *testing.B)   { benchmarkAddMulVVW(b, 3) }
-func BenchmarkAddMulVVW_4(b *testing.B)   { benchmarkAddMulVVW(b, 4) }
-func BenchmarkAddMulVVW_5(b *testing.B)   { benchmarkAddMulVVW(b, 5) }
-func BenchmarkAddMulVVW_1e1(b *testing.B) { benchmarkAddMulVVW(b, 1e1) }
-func BenchmarkAddMulVVW_1e2(b *testing.B) { benchmarkAddMulVVW(b, 1e2) }
-func BenchmarkAddMulVVW_1e3(b *testing.B) { benchmarkAddMulVVW(b, 1e3) }
-func BenchmarkAddMulVVW_1e4(b *testing.B) { benchmarkAddMulVVW(b, 1e4) }
-func BenchmarkAddMulVVW_1e5(b *testing.B) { benchmarkAddMulVVW(b, 1e5) }
-
 func testWordBitLen(t *testing.T, fname string, f func(Word) int) {
 	for i := 0; i <= _W; i++ {
 		x := Word(1) << uint(i-1) // i == 0 => x == 0
@@ -435,23 +399,15 @@ func TestWordBitLen(t *testing.T) {
 }
 
 // runs b.N iterations of bitLen called on a Word containing (1 << nbits)-1.
-func benchmarkBitLenN(b *testing.B, nbits uint) {
-	testword := Word((uint64(1) << nbits) - 1)
-	for i := 0; i < b.N; i++ {
-		bitLen(testword)
+func BenchmarkBitLen(b *testing.B) {
+	// Individual bitLen tests. Numbers chosen to examine both sides
+	// of powers-of-two boundaries.
+	for _, nbits := range []uint{0, 1, 2, 3, 4, 5, 8, 9, 16, 17, 31} {
+		testword := Word((uint64(1) << nbits) - 1)
+		b.Run(fmt.Sprint(nbits), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				bitLen(testword)
+			}
+		})
 	}
 }
-
-// Individual bitLen tests.  Numbers chosen to examine both sides
-// of powers-of-two boundaries.
-func BenchmarkBitLen0(b *testing.B)  { benchmarkBitLenN(b, 0) }
-func BenchmarkBitLen1(b *testing.B)  { benchmarkBitLenN(b, 1) }
-func BenchmarkBitLen2(b *testing.B)  { benchmarkBitLenN(b, 2) }
-func BenchmarkBitLen3(b *testing.B)  { benchmarkBitLenN(b, 3) }
-func BenchmarkBitLen4(b *testing.B)  { benchmarkBitLenN(b, 4) }
-func BenchmarkBitLen5(b *testing.B)  { benchmarkBitLenN(b, 5) }
-func BenchmarkBitLen8(b *testing.B)  { benchmarkBitLenN(b, 8) }
-func BenchmarkBitLen9(b *testing.B)  { benchmarkBitLenN(b, 9) }
-func BenchmarkBitLen16(b *testing.B) { benchmarkBitLenN(b, 16) }
-func BenchmarkBitLen17(b *testing.B) { benchmarkBitLenN(b, 17) }
-func BenchmarkBitLen31(b *testing.B) { benchmarkBitLenN(b, 31) }
diff --git a/libgo/go/math/big/float.go b/libgo/go/math/big/float.go
index b1c748c9a54..7a9c2b3dfb2 100644
--- a/libgo/go/math/big/float.go
+++ b/libgo/go/math/big/float.go
@@ -392,15 +392,13 @@ func (z *Float) round(sbit uint) {
 	// m > 0 implies z.prec > 0 (checked by validate)
 
 	m := uint32(len(z.mant)) // present mantissa length in words
-	bits := m * _W           // present mantissa bits
+	bits := m * _W           // present mantissa bits; bits > 0
 	if bits <= z.prec {
 		// mantissa fits => nothing to do
 		return
 	}
 	// bits > z.prec
 
-	n := (z.prec + (_W - 1)) / _W // mantissa length in words for desired precision
-
 	// Rounding is based on two bits: the rounding bit (rbit) and the
 	// sticky bit (sbit). The rbit is the bit immediately before the
 	// z.prec leading mantissa bits (the "0.5"). The sbit is set if any
@@ -415,111 +413,77 @@ func (z *Float) round(sbit uint) {
 
 	// bits > z.prec: mantissa too large => round
 	r := uint(bits - z.prec - 1) // rounding bit position; r >= 0
-	rbit := z.mant.bit(r)        // rounding bit
+	rbit := z.mant.bit(r) & 1    // rounding bit; be safe and ensure it's a single bit
 	if sbit == 0 {
+		// TODO(gri) if rbit != 0 we don't need to compute sbit for some rounding modes (optimization)
 		sbit = z.mant.sticky(r)
 	}
-	if debugFloat && sbit&^1 != 0 {
-		panic(fmt.Sprintf("invalid sbit %#x", sbit))
-	}
-
-	// convert ToXInf rounding modes
-	mode := z.mode
-	switch mode {
-	case ToNegativeInf:
-		mode = ToZero
-		if z.neg {
-			mode = AwayFromZero
-		}
-	case ToPositiveInf:
-		mode = AwayFromZero
-		if z.neg {
-			mode = ToZero
-		}
-	}
+	sbit &= 1 // be safe and ensure it's a single bit
 
 	// cut off extra words
+	n := (z.prec + (_W - 1)) / _W // mantissa length in words for desired precision
 	if m > n {
 		copy(z.mant, z.mant[m-n:]) // move n last words to front
 		z.mant = z.mant[:n]
 	}
 
-	// determine number of trailing zero bits t
-	t := n*_W - z.prec // 0 <= t < _W
-	lsb := Word(1) << t
-
-	// make rounding decision
-	// TODO(gri) This can be simplified (see Bits.round in bits_test.go).
-	switch mode {
-	case ToZero:
-		// nothing to do
-	case ToNearestEven, ToNearestAway:
-		if rbit == 0 {
-			// rounding bits == 0b0x
-			mode = ToZero
-		} else if sbit == 1 {
-			// rounding bits == 0b11
-			mode = AwayFromZero
-		}
-	case AwayFromZero:
-		if rbit|sbit == 0 {
-			mode = ToZero
-		}
-	default:
-		// ToXInf modes have been converted to ToZero or AwayFromZero
-		panic("unreachable")
-	}
-
-	// round and determine accuracy
-	switch mode {
-	case ToZero:
-		if rbit|sbit != 0 {
-			z.acc = Below
+	// determine number of trailing zero bits (ntz) and compute lsb mask of mantissa's least-significant word
+	ntz := n*_W - z.prec // 0 <= ntz < _W
+	lsb := Word(1) << ntz
+
+	// round if result is inexact
+	if rbit|sbit != 0 {
+		// Make rounding decision: The result mantissa is truncated ("rounded down")
+		// by default. Decide if we need to increment, or "round up", the (unsigned)
+		// mantissa.
+		inc := false
+		switch z.mode {
+		case ToNegativeInf:
+			inc = z.neg
+		case ToZero:
+			// nothing to do
+		case ToNearestEven:
+			inc = rbit != 0 && (sbit != 0 || z.mant[0]&lsb != 0)
+		case ToNearestAway:
+			inc = rbit != 0
+		case AwayFromZero:
+			inc = true
+		case ToPositiveInf:
+			inc = !z.neg
+		default:
+			panic("unreachable")
 		}
 
-	case ToNearestEven, ToNearestAway:
-		if debugFloat && rbit != 1 {
-			panic("internal error in rounding")
-		}
-		if mode == ToNearestEven && sbit == 0 && z.mant[0]&lsb == 0 {
-			z.acc = Below
-			break
-		}
-		// mode == ToNearestAway || sbit == 1 || z.mant[0]&lsb != 0
-		fallthrough
-
-	case AwayFromZero:
-		// add 1 to mantissa
-		if addVW(z.mant, z.mant, lsb) != 0 {
-			// overflow => shift mantissa right by 1 and add msb
-			shrVU(z.mant, z.mant, 1)
-			z.mant[n-1] |= 1 << (_W - 1)
-			// adjust exponent
-			if z.exp < MaxExp {
+		// A positive result (!z.neg) is Above the exact result if we increment,
+		// and it's Below if we truncate (Exact results require no rounding).
+		// For a negative result (z.neg) it is exactly the opposite.
+		z.acc = makeAcc(inc != z.neg)
+
+		if inc {
+			// add 1 to mantissa
+			if addVW(z.mant, z.mant, lsb) != 0 {
+				// mantissa overflow => adjust exponent
+				if z.exp >= MaxExp {
+					// exponent overflow
+					z.form = inf
+					return
+				}
 				z.exp++
-			} else {
-				// exponent overflow
-				z.acc = makeAcc(!z.neg)
-				z.form = inf
-				return
+				// adjust mantissa: divide by 2 to compensate for exponent adjustment
+				shrVU(z.mant, z.mant, 1)
+				// set msb == carry == 1 from the mantissa overflow above
+				const msb = 1 << (_W - 1)
+				z.mant[n-1] |= msb
 			}
 		}
-		z.acc = Above
 	}
 
 	// zero out trailing bits in least-significant word
 	z.mant[0] &^= lsb - 1
 
-	// update accuracy
-	if z.acc != Exact && z.neg {
-		z.acc = -z.acc
-	}
-
 	if debugFloat {
 		z.validate()
 	}
-
-	return
 }
 
 func (z *Float) setBits64(neg bool, x uint64) *Float {
@@ -874,21 +838,43 @@ func (x *Float) Float32() (float32, Accuracy) {
 			emax  = bias              //   127  largest unbiased exponent (normal)
 		)
 
-		// Float mantissa m is 0.5 <= m < 1.0; compute exponent for floatxx mantissa.
-		e := x.exp - 1 // exponent for mantissa m with 1.0 <= m < 2.0
-		p := mbits + 1 // precision of normal float
+		// Float mantissa m is 0.5 <= m < 1.0; compute exponent e for float32 mantissa.
+		e := x.exp - 1 // exponent for normal mantissa m with 1.0 <= m < 2.0
 
-		// If the exponent is too small, we may have a denormal number
-		// in which case we have fewer mantissa bits available: reduce
-		// precision accordingly.
+		// Compute precision p for float32 mantissa.
+		// If the exponent is too small, we have a denormal number before
+		// rounding and fewer than p mantissa bits of precision available
+		// (the exponent remains fixed but the mantissa gets shifted right).
+		p := mbits + 1 // precision of normal float
 		if e < emin {
-			p -= emin - int(e)
-			// Make sure we have at least 1 bit so that we don't
-			// lose numbers rounded up to the smallest denormal.
-			if p < 1 {
-				p = 1
+			// recompute precision
+			p = mbits + 1 - emin + int(e)
+			// If p == 0, the mantissa of x is shifted so much to the right
+			// that its msb falls immediately to the right of the float32
+			// mantissa space. In other words, if the smallest denormal is
+			// considered "1.0", for p == 0, the mantissa value m is >= 0.5.
+			// If m > 0.5, it is rounded up to 1.0; i.e., the smallest denormal.
+			// If m == 0.5, it is rounded down to even, i.e., 0.0.
+			// If p < 0, the mantissa value m is <= "0.25" which is never rounded up.
+			if p < 0 /* m <= 0.25 */ || p == 0 && x.mant.sticky(uint(len(x.mant))*_W-1) == 0 /* m == 0.5 */ {
+				// underflow to ±0
+				if x.neg {
+					var z float32
+					return -z, Above
+				}
+				return 0.0, Below
+			}
+			// otherwise, round up
+			// We handle p == 0 explicitly because it's easy and because
+			// Float.round doesn't support rounding to 0 bits of precision.
+			if p == 0 {
+				if x.neg {
+					return -math.SmallestNonzeroFloat32, Below
+				}
+				return math.SmallestNonzeroFloat32, Above
 			}
 		}
+		// p > 0
 
 		// round
 		var r Float
@@ -898,12 +884,8 @@ func (x *Float) Float32() (float32, Accuracy) {
 
 		// Rounding may have caused r to overflow to ±Inf
 		// (rounding never causes underflows to 0).
-		if r.form == inf {
-			e = emax + 1 // cause overflow below
-		}
-
-		// If the exponent is too large, overflow to ±Inf.
-		if e > emax {
+		// If the exponent is too large, also overflow to ±Inf.
+		if r.form == inf || e > emax {
 			// overflow
 			if x.neg {
 				return float32(math.Inf(-1)), Below
@@ -921,17 +903,12 @@ func (x *Float) Float32() (float32, Accuracy) {
 		// Rounding may have caused a denormal number to
 		// become normal. Check again.
 		if e < emin {
-			// denormal number
-			if e < dmin {
-				// underflow to ±0
-				if x.neg {
-					var z float32
-					return -z, Above
-				}
-				return 0.0, Below
-			}
-			// bexp = 0
-			mant = msb32(r.mant) >> (fbits - r.prec)
+			// denormal number: recompute precision
+			// Since rounding may have at best increased precision
+			// and we have eliminated p <= 0 early, we know p > 0.
+			// bexp == 0 for denormals
+			p = mbits + 1 - emin + int(e)
+			mant = msb32(r.mant) >> uint(fbits-p)
 		} else {
 			// normal number: emin <= e <= emax
 			bexp = uint32(e+bias) << mbits
@@ -981,21 +958,43 @@ func (x *Float) Float64() (float64, Accuracy) {
 			emax  = bias              //  1023  largest unbiased exponent (normal)
 		)
 
-		// Float mantissa m is 0.5 <= m < 1.0; compute exponent for floatxx mantissa.
-		e := x.exp - 1 // exponent for mantissa m with 1.0 <= m < 2.0
-		p := mbits + 1 // precision of normal float
+		// Float mantissa m is 0.5 <= m < 1.0; compute exponent e for float64 mantissa.
+		e := x.exp - 1 // exponent for normal mantissa m with 1.0 <= m < 2.0
 
-		// If the exponent is too small, we may have a denormal number
-		// in which case we have fewer mantissa bits available: reduce
-		// precision accordingly.
+		// Compute precision p for float64 mantissa.
+		// If the exponent is too small, we have a denormal number before
+		// rounding and fewer than p mantissa bits of precision available
+		// (the exponent remains fixed but the mantissa gets shifted right).
+		p := mbits + 1 // precision of normal float
 		if e < emin {
-			p -= emin - int(e)
-			// Make sure we have at least 1 bit so that we don't
-			// lose numbers rounded up to the smallest denormal.
-			if p < 1 {
-				p = 1
+			// recompute precision
+			p = mbits + 1 - emin + int(e)
+			// If p == 0, the mantissa of x is shifted so much to the right
+			// that its msb falls immediately to the right of the float64
+			// mantissa space. In other words, if the smallest denormal is
+			// considered "1.0", for p == 0, the mantissa value m is >= 0.5.
+			// If m > 0.5, it is rounded up to 1.0; i.e., the smallest denormal.
+			// If m == 0.5, it is rounded down to even, i.e., 0.0.
+			// If p < 0, the mantissa value m is <= "0.25" which is never rounded up.
+			if p < 0 /* m <= 0.25 */ || p == 0 && x.mant.sticky(uint(len(x.mant))*_W-1) == 0 /* m == 0.5 */ {
+				// underflow to ±0
+				if x.neg {
+					var z float64
+					return -z, Above
+				}
+				return 0.0, Below
+			}
+			// otherwise, round up
+			// We handle p == 0 explicitly because it's easy and because
+			// Float.round doesn't support rounding to 0 bits of precision.
+			if p == 0 {
+				if x.neg {
+					return -math.SmallestNonzeroFloat64, Below
+				}
+				return math.SmallestNonzeroFloat64, Above
 			}
 		}
+		// p > 0
 
 		// round
 		var r Float
@@ -1005,12 +1004,8 @@ func (x *Float) Float64() (float64, Accuracy) {
 
 		// Rounding may have caused r to overflow to ±Inf
 		// (rounding never causes underflows to 0).
-		if r.form == inf {
-			e = emax + 1 // cause overflow below
-		}
-
-		// If the exponent is too large, overflow to ±Inf.
-		if e > emax {
+		// If the exponent is too large, also overflow to ±Inf.
+		if r.form == inf || e > emax {
 			// overflow
 			if x.neg {
 				return math.Inf(-1), Below
@@ -1028,17 +1023,12 @@ func (x *Float) Float64() (float64, Accuracy) {
 		// Rounding may have caused a denormal number to
 		// become normal. Check again.
 		if e < emin {
-			// denormal number
-			if e < dmin {
-				// underflow to ±0
-				if x.neg {
-					var z float64
-					return -z, Above
-				}
-				return 0.0, Below
-			}
-			// bexp = 0
-			mant = msb64(r.mant) >> (fbits - r.prec)
+			// denormal number: recompute precision
+			// Since rounding may have at best increased precision
+			// and we have eliminated p <= 0 early, we know p > 0.
+			// bexp == 0 for denormals
+			p = mbits + 1 - emin + int(e)
+			mant = msb64(r.mant) >> uint(fbits-p)
 		} else {
 			// normal number: emin <= e <= emax
 			bexp = uint64(e+bias) << mbits
@@ -1427,7 +1417,7 @@ func (z *Float) Add(x, y *Float) *Float {
 	}
 
 	if x.form == finite && y.form == finite {
-		// x + y (commom case)
+		// x + y (common case)
 		z.neg = x.neg
 		if x.neg == y.neg {
 			// x + y == x + y
diff --git a/libgo/go/math/big/float_test.go b/libgo/go/math/big/float_test.go
index d3b214b631d..464619b3380 100644
--- a/libgo/go/math/big/float_test.go
+++ b/libgo/go/math/big/float_test.go
@@ -829,7 +829,7 @@ func TestFloatFloat32(t *testing.T) {
 	}{
 		{"0", 0, Exact},
 
-		// underflow
+		// underflow to zero
 		{"1e-1000", 0, Below},
 		{"0x0.000002p-127", 0, Below},
 		{"0x.0000010p-126", 0, Below},
@@ -843,6 +843,46 @@ func TestFloatFloat32(t *testing.T) {
 		{"1p-149", math.SmallestNonzeroFloat32, Exact},
 		{"0x.fffffep-126", math.Float32frombits(0x7fffff), Exact}, // largest denormal
 
+		// special denormal cases (see issues 14553, 14651)
+		{"0x0.0000001p-126", math.Float32frombits(0x00000000), Below}, // underflow to zero
+		{"0x0.0000008p-126", math.Float32frombits(0x00000000), Below}, // underflow to zero
+		{"0x0.0000010p-126", math.Float32frombits(0x00000000), Below}, // rounded down to even
+		{"0x0.0000011p-126", math.Float32frombits(0x00000001), Above}, // rounded up to smallest denormal
+		{"0x0.0000018p-126", math.Float32frombits(0x00000001), Above}, // rounded up to smallest denormal
+
+		{"0x1.0000000p-149", math.Float32frombits(0x00000001), Exact}, // smallest denormal
+		{"0x0.0000020p-126", math.Float32frombits(0x00000001), Exact}, // smallest denormal
+		{"0x0.fffffe0p-126", math.Float32frombits(0x007fffff), Exact}, // largest denormal
+		{"0x1.0000000p-126", math.Float32frombits(0x00800000), Exact}, // smallest normal
+
+		{"0x0.8p-149", math.Float32frombits(0x000000000), Below}, // rounded down to even
+		{"0x0.9p-149", math.Float32frombits(0x000000001), Above}, // rounded up to smallest denormal
+		{"0x0.ap-149", math.Float32frombits(0x000000001), Above}, // rounded up to smallest denormal
+		{"0x0.bp-149", math.Float32frombits(0x000000001), Above}, // rounded up to smallest denormal
+		{"0x0.cp-149", math.Float32frombits(0x000000001), Above}, // rounded up to smallest denormal
+
+		{"0x1.0p-149", math.Float32frombits(0x000000001), Exact}, // smallest denormal
+		{"0x1.7p-149", math.Float32frombits(0x000000001), Below},
+		{"0x1.8p-149", math.Float32frombits(0x000000002), Above},
+		{"0x1.9p-149", math.Float32frombits(0x000000002), Above},
+
+		{"0x2.0p-149", math.Float32frombits(0x000000002), Exact},
+		{"0x2.8p-149", math.Float32frombits(0x000000002), Below}, // rounded down to even
+		{"0x2.9p-149", math.Float32frombits(0x000000003), Above},
+
+		{"0x3.0p-149", math.Float32frombits(0x000000003), Exact},
+		{"0x3.7p-149", math.Float32frombits(0x000000003), Below},
+		{"0x3.8p-149", math.Float32frombits(0x000000004), Above}, // rounded up to even
+
+		{"0x4.0p-149", math.Float32frombits(0x000000004), Exact},
+		{"0x4.8p-149", math.Float32frombits(0x000000004), Below}, // rounded down to even
+		{"0x4.9p-149", math.Float32frombits(0x000000005), Above},
+
+		// specific case from issue 14553
+		{"0x7.7p-149", math.Float32frombits(0x000000007), Below},
+		{"0x7.8p-149", math.Float32frombits(0x000000008), Above},
+		{"0x7.9p-149", math.Float32frombits(0x000000008), Above},
+
 		// normals
 		{"0x.ffffffp-126", math.Float32frombits(0x00800000), Above}, // rounded up to smallest normal
 		{"1p-126", math.Float32frombits(0x00800000), Exact},         // smallest normal
@@ -881,7 +921,7 @@ func TestFloatFloat32(t *testing.T) {
 			x := makeFloat(tx)
 			out, acc := x.Float32()
 			if !alike32(out, tout) || acc != tacc {
-				t.Errorf("%s: got %g (%#x, %s); want %g (%#x, %s)", tx, out, math.Float32bits(out), acc, test.out, math.Float32bits(test.out), tacc)
+				t.Errorf("%s: got %g (%#08x, %s); want %g (%#08x, %s)", tx, out, math.Float32bits(out), acc, test.out, math.Float32bits(test.out), tacc)
 			}
 
 			// test that x.SetFloat64(float64(f)).Float32() == f
@@ -903,18 +943,48 @@ func TestFloatFloat64(t *testing.T) {
 	}{
 		{"0", 0, Exact},
 
-		// underflow
+		// underflow to zero
 		{"1e-1000", 0, Below},
 		{"0x0.0000000000001p-1023", 0, Below},
 		{"0x0.00000000000008p-1022", 0, Below},
 
 		// denormals
 		{"0x0.0000000000000cp-1022", math.SmallestNonzeroFloat64, Above}, // rounded up to smallest denormal
-		{"0x0.0000000000001p-1022", math.SmallestNonzeroFloat64, Exact},  // smallest denormal
+		{"0x0.00000000000010p-1022", math.SmallestNonzeroFloat64, Exact}, // smallest denormal
 		{"0x.8p-1073", math.SmallestNonzeroFloat64, Exact},
 		{"1p-1074", math.SmallestNonzeroFloat64, Exact},
 		{"0x.fffffffffffffp-1022", math.Float64frombits(0x000fffffffffffff), Exact}, // largest denormal
 
+		// special denormal cases (see issues 14553, 14651)
+		{"0x0.00000000000001p-1022", math.Float64frombits(0x00000000000000000), Below}, // underflow to zero
+		{"0x0.00000000000004p-1022", math.Float64frombits(0x00000000000000000), Below}, // underflow to zero
+		{"0x0.00000000000008p-1022", math.Float64frombits(0x00000000000000000), Below}, // rounded down to even
+		{"0x0.00000000000009p-1022", math.Float64frombits(0x00000000000000001), Above}, // rounded up to smallest denormal
+		{"0x0.0000000000000ap-1022", math.Float64frombits(0x00000000000000001), Above}, // rounded up to smallest denormal
+
+		{"0x0.8p-1074", math.Float64frombits(0x00000000000000000), Below}, // rounded down to even
+		{"0x0.9p-1074", math.Float64frombits(0x00000000000000001), Above}, // rounded up to smallest denormal
+		{"0x0.ap-1074", math.Float64frombits(0x00000000000000001), Above}, // rounded up to smallest denormal
+		{"0x0.bp-1074", math.Float64frombits(0x00000000000000001), Above}, // rounded up to smallest denormal
+		{"0x0.cp-1074", math.Float64frombits(0x00000000000000001), Above}, // rounded up to smallest denormal
+
+		{"0x1.0p-1074", math.Float64frombits(0x00000000000000001), Exact},
+		{"0x1.7p-1074", math.Float64frombits(0x00000000000000001), Below},
+		{"0x1.8p-1074", math.Float64frombits(0x00000000000000002), Above},
+		{"0x1.9p-1074", math.Float64frombits(0x00000000000000002), Above},
+
+		{"0x2.0p-1074", math.Float64frombits(0x00000000000000002), Exact},
+		{"0x2.8p-1074", math.Float64frombits(0x00000000000000002), Below}, // rounded down to even
+		{"0x2.9p-1074", math.Float64frombits(0x00000000000000003), Above},
+
+		{"0x3.0p-1074", math.Float64frombits(0x00000000000000003), Exact},
+		{"0x3.7p-1074", math.Float64frombits(0x00000000000000003), Below},
+		{"0x3.8p-1074", math.Float64frombits(0x00000000000000004), Above}, // rounded up to even
+
+		{"0x4.0p-1074", math.Float64frombits(0x00000000000000004), Exact},
+		{"0x4.8p-1074", math.Float64frombits(0x00000000000000004), Below}, // rounded down to even
+		{"0x4.9p-1074", math.Float64frombits(0x00000000000000005), Above},
+
 		// normals
 		{"0x.fffffffffffff8p-1022", math.Float64frombits(0x0010000000000000), Above}, // rounded up to smallest normal
 		{"1p-1022", math.Float64frombits(0x0010000000000000), Exact},                 // smallest normal
@@ -958,7 +1028,7 @@ func TestFloatFloat64(t *testing.T) {
 			x := makeFloat(tx)
 			out, acc := x.Float64()
 			if !alike64(out, tout) || acc != tacc {
-				t.Errorf("%s: got %g (%#x, %s); want %g (%#x, %s)", tx, out, math.Float64bits(out), acc, test.out, math.Float64bits(test.out), tacc)
+				t.Errorf("%s: got %g (%#016x, %s); want %g (%#016x, %s)", tx, out, math.Float64bits(out), acc, test.out, math.Float64bits(test.out), tacc)
 			}
 
 			// test that x.SetFloat64(f).Float64() == f
diff --git a/libgo/go/math/big/floatconv.go b/libgo/go/math/big/floatconv.go
index 37d5c06a6f3..a884df6fe1c 100644
--- a/libgo/go/math/big/floatconv.go
+++ b/libgo/go/math/big/floatconv.go
@@ -85,7 +85,7 @@ func (z *Float) scan(r io.ByteScanner, base int) (f *Float, b int, err error) {
 	if fcount < 0 {
 		// The mantissa has a "decimal" point ddd.dddd; and
 		// -fcount is the number of digits to the right of '.'.
-		// Adjust relevant exponent accodingly.
+		// Adjust relevant exponent accordingly.
 		d := int64(fcount)
 		switch b {
 		case 10:
diff --git a/libgo/go/math/big/floatconv_test.go b/libgo/go/math/big/floatconv_test.go
index b6f99936082..b2a1ab05fcc 100644
--- a/libgo/go/math/big/floatconv_test.go
+++ b/libgo/go/math/big/floatconv_test.go
@@ -290,6 +290,11 @@ func TestFloat64Text(t *testing.T) {
 		// Issue 2625.
 		{383260575764816448, 'f', 0, "383260575764816448"},
 		{383260575764816448, 'g', -1, "3.8326057576481645e+17"},
+
+		// Issue 15918.
+		{1, 'f', -10, "1"},
+		{1, 'f', -11, "1"},
+		{1, 'f', -12, "1"},
 	} {
 		// The test cases are from the strconv package which tests float64 values.
 		// When formatting values with prec = -1 (shortest representation),
diff --git a/libgo/go/math/big/floatmarsh.go b/libgo/go/math/big/floatmarsh.go
index 44987ee03a6..3725d4b8345 100644
--- a/libgo/go/math/big/floatmarsh.go
+++ b/libgo/go/math/big/floatmarsh.go
@@ -6,7 +6,94 @@
 
 package big
 
-import "fmt"
+import (
+	"encoding/binary"
+	"fmt"
+)
+
+// Gob codec version. Permits backward-compatible changes to the encoding.
+const floatGobVersion byte = 1
+
+// GobEncode implements the gob.GobEncoder interface.
+// The Float value and all its attributes (precision,
+// rounding mode, accuracy) are marshalled.
+func (x *Float) GobEncode() ([]byte, error) {
+	if x == nil {
+		return nil, nil
+	}
+
+	// determine max. space (bytes) required for encoding
+	sz := 1 + 1 + 4 // version + mode|acc|form|neg (3+2+2+1bit) + prec
+	n := 0          // number of mantissa words
+	if x.form == finite {
+		// add space for mantissa and exponent
+		n = int((x.prec + (_W - 1)) / _W) // required mantissa length in words for given precision
+		// actual mantissa slice could be shorter (trailing 0's) or longer (unused bits):
+		// - if shorter, only encode the words present
+		// - if longer, cut off unused words when encoding in bytes
+		//   (in practice, this should never happen since rounding
+		//   takes care of it, but be safe and do it always)
+		if len(x.mant) < n {
+			n = len(x.mant)
+		}
+		// len(x.mant) >= n
+		sz += 4 + n*_S // exp + mant
+	}
+	buf := make([]byte, sz)
+
+	buf[0] = floatGobVersion
+	b := byte(x.mode&7)<<5 | byte((x.acc+1)&3)<<3 | byte(x.form&3)<<1
+	if x.neg {
+		b |= 1
+	}
+	buf[1] = b
+	binary.BigEndian.PutUint32(buf[2:], x.prec)
+
+	if x.form == finite {
+		binary.BigEndian.PutUint32(buf[6:], uint32(x.exp))
+		x.mant[len(x.mant)-n:].bytes(buf[10:]) // cut off unused trailing words
+	}
+
+	return buf, nil
+}
+
+// GobDecode implements the gob.GobDecoder interface.
+// The result is rounded per the precision and rounding mode of
+// z unless z's precision is 0, in which case z is set exactly
+// to the decoded value.
+func (z *Float) GobDecode(buf []byte) error {
+	if len(buf) == 0 {
+		// Other side sent a nil or default value.
+		*z = Float{}
+		return nil
+	}
+
+	if buf[0] != floatGobVersion {
+		return fmt.Errorf("Float.GobDecode: encoding version %d not supported", buf[0])
+	}
+
+	oldPrec := z.prec
+	oldMode := z.mode
+
+	b := buf[1]
+	z.mode = RoundingMode((b >> 5) & 7)
+	z.acc = Accuracy((b>>3)&3) - 1
+	z.form = form((b >> 1) & 3)
+	z.neg = b&1 != 0
+	z.prec = binary.BigEndian.Uint32(buf[2:])
+
+	if z.form == finite {
+		z.exp = int32(binary.BigEndian.Uint32(buf[6:]))
+		z.mant = z.mant.setBytes(buf[10:])
+	}
+
+	if oldPrec != 0 {
+		z.mode = oldMode
+		z.SetPrec(uint(oldPrec))
+	}
+
+	return nil
+}
 
 // MarshalText implements the encoding.TextMarshaler interface.
 // Only the Float value is marshaled (in full precision), other
diff --git a/libgo/go/math/big/floatmarsh_test.go b/libgo/go/math/big/floatmarsh_test.go
index d7ef2fca68f..5bd906ddae4 100644
--- a/libgo/go/math/big/floatmarsh_test.go
+++ b/libgo/go/math/big/floatmarsh_test.go
@@ -5,7 +5,10 @@
 package big
 
 import (
+	"bytes"
+	"encoding/gob"
 	"encoding/json"
+	"io"
 	"testing"
 )
 
@@ -23,6 +26,85 @@ var floatVals = []string{
 	"Inf",
 }
 
+func TestFloatGobEncoding(t *testing.T) {
+	var medium bytes.Buffer
+	enc := gob.NewEncoder(&medium)
+	dec := gob.NewDecoder(&medium)
+	for _, test := range floatVals {
+		for _, sign := range []string{"", "+", "-"} {
+			for _, prec := range []uint{0, 1, 2, 10, 53, 64, 100, 1000} {
+				for _, mode := range []RoundingMode{ToNearestEven, ToNearestAway, ToZero, AwayFromZero, ToNegativeInf, ToPositiveInf} {
+					medium.Reset() // empty buffer for each test case (in case of failures)
+					x := sign + test
+
+					var tx Float
+					_, _, err := tx.SetPrec(prec).SetMode(mode).Parse(x, 0)
+					if err != nil {
+						t.Errorf("parsing of %s (%dbits, %v) failed (invalid test case): %v", x, prec, mode, err)
+						continue
+					}
+
+					// If tx was set to prec == 0, tx.Parse(x, 0) assumes precision 64. Correct it.
+					if prec == 0 {
+						tx.SetPrec(0)
+					}
+
+					if err := enc.Encode(&tx); err != nil {
+						t.Errorf("encoding of %v (%dbits, %v) failed: %v", &tx, prec, mode, err)
+						continue
+					}
+
+					var rx Float
+					if err := dec.Decode(&rx); err != nil {
+						t.Errorf("decoding of %v (%dbits, %v) failed: %v", &tx, prec, mode, err)
+						continue
+					}
+
+					if rx.Cmp(&tx) != 0 {
+						t.Errorf("transmission of %s failed: got %s want %s", x, rx.String(), tx.String())
+						continue
+					}
+
+					if rx.Prec() != prec {
+						t.Errorf("transmission of %s's prec failed: got %d want %d", x, rx.Prec(), prec)
+					}
+
+					if rx.Mode() != mode {
+						t.Errorf("transmission of %s's mode failed: got %s want %s", x, rx.Mode(), mode)
+					}
+
+					if rx.Acc() != tx.Acc() {
+						t.Errorf("transmission of %s's accuracy failed: got %s want %s", x, rx.Acc(), tx.Acc())
+					}
+				}
+			}
+		}
+	}
+}
+
+func TestFloatCorruptGob(t *testing.T) {
+	var buf bytes.Buffer
+	tx := NewFloat(4 / 3).SetPrec(1000).SetMode(ToPositiveInf)
+	if err := gob.NewEncoder(&buf).Encode(tx); err != nil {
+		t.Fatal(err)
+	}
+	b := buf.Bytes()
+
+	var rx Float
+	if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&rx); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := gob.NewDecoder(bytes.NewReader(b[:10])).Decode(&rx); err != io.ErrUnexpectedEOF {
+		t.Errorf("got %v want EOF", err)
+	}
+
+	b[1] = 0
+	if err := gob.NewDecoder(bytes.NewReader(b)).Decode(&rx); err == nil {
+		t.Fatal("got nil want version error")
+	}
+}
+
 func TestFloatJSONEncoding(t *testing.T) {
 	for _, test := range floatVals {
 		for _, sign := range []string{"", "+", "-"} {
diff --git a/libgo/go/math/big/ftoa.go b/libgo/go/math/big/ftoa.go
index c5cdb5eb705..57b16e1ad1f 100644
--- a/libgo/go/math/big/ftoa.go
+++ b/libgo/go/math/big/ftoa.go
@@ -41,8 +41,11 @@ import (
 // x.Prec() mantissa bits.
 // The prec value is ignored for the 'b' or 'p' format.
 func (x *Float) Text(format byte, prec int) string {
-	const extra = 10 // TODO(gri) determine a good/better value here
-	return string(x.Append(make([]byte, 0, prec+extra), format, prec))
+	cap := 10 // TODO(gri) determine a good/better value here
+	if prec > 0 {
+		cap += prec
+	}
+	return string(x.Append(make([]byte, 0, cap), format, prec))
 }
 
 // String formats x like x.Text('g', 10).
@@ -333,9 +336,9 @@ func (x *Float) fmtB(buf []byte) []byte {
 	return strconv.AppendInt(buf, e, 10)
 }
 
-// fmtP appends the string of x in the format 0x." mantissa "p" exponent
-// with a hexadecimal mantissa and a binary exponent, or 0" if x is zero,
-// ad returns the extended buffer.
+// fmtP appends the string of x in the format "0x." mantissa "p" exponent
+// with a hexadecimal mantissa and a binary exponent, or "0" if x is zero,
+// and returns the extended buffer.
 // The mantissa is normalized such that 0.5 <= 0.mantissa < 1.0.
 // The sign of x is ignored, and x must not be an Inf.
 func (x *Float) fmtP(buf []byte) []byte {
@@ -374,12 +377,11 @@ func min(x, y int) int {
 }
 
 // Format implements fmt.Formatter. It accepts all the regular
-// formats for floating-point numbers ('e', 'E', 'f', 'F', 'g',
-// 'G') as well as 'b', 'p', and 'v'. See (*Float).Text for the
-// interpretation of 'b' and 'p'. The 'v' format is handled like
-// 'g'.
+// formats for floating-point numbers ('b', 'e', 'E', 'f', 'F',
+// 'g', 'G') as well as 'p' and 'v'. See (*Float).Text for the
+// interpretation of 'p'. The 'v' format is handled like 'g'.
 // Format also supports specification of the minimum precision
-// in digits, the output field width, as well as the format verbs
+// in digits, the output field width, as well as the format flags
 // '+' and ' ' for sign control, '0' for space or zero padding,
 // and '-' for left or right justification. See the fmt package
 // for details.
diff --git a/libgo/go/math/big/gcd_test.go b/libgo/go/math/big/gcd_test.go
index c0b9f583000..a929bf597f4 100644
--- a/libgo/go/math/big/gcd_test.go
+++ b/libgo/go/math/big/gcd_test.go
@@ -20,13 +20,27 @@ func randInt(r *rand.Rand, size uint) *Int {
 }
 
 func runGCD(b *testing.B, aSize, bSize uint) {
+	b.Run("WithoutXY", func(b *testing.B) {
+		runGCDExt(b, aSize, bSize, false)
+	})
+	b.Run("WithXY", func(b *testing.B) {
+		runGCDExt(b, aSize, bSize, true)
+	})
+}
+
+func runGCDExt(b *testing.B, aSize, bSize uint, calcXY bool) {
 	b.StopTimer()
 	var r = rand.New(rand.NewSource(1234))
 	aa := randInt(r, aSize)
 	bb := randInt(r, bSize)
+	var x, y *Int
+	if calcXY {
+		x = new(Int)
+		y = new(Int)
+	}
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
-		new(Int).GCD(nil, nil, aa, bb)
+		new(Int).GCD(x, y, aa, bb)
 	}
 }
 
diff --git a/libgo/go/math/big/int.go b/libgo/go/math/big/int.go
index 67ab7042ffe..f2a75d1cd50 100644
--- a/libgo/go/math/big/int.go
+++ b/libgo/go/math/big/int.go
@@ -459,11 +459,11 @@ func (z *Int) GCD(x, y, a, b *Int) *Int {
 	q := new(Int)
 	temp := new(Int)
 
+	r := new(Int)
 	for len(B.abs) > 0 {
-		r := new(Int)
 		q, r = q.QuoRem(A, B, r)
 
-		A, B = B, r
+		A, B, r = B, r, A
 
 		temp.Set(X)
 		X.Mul(X, q)
diff --git a/libgo/go/math/big/intconv.go b/libgo/go/math/big/intconv.go
index 56a75f87ae2..daf674aef4e 100644
--- a/libgo/go/math/big/intconv.go
+++ b/libgo/go/math/big/intconv.go
@@ -52,16 +52,16 @@ func writeMultiple(s fmt.State, text string, count int) {
 	}
 }
 
-// Format is a support routine for fmt.Formatter. It accepts
-// the formats 'b' (binary), 'o' (octal), 'd' (decimal), 'x'
-// (lowercase hexadecimal), and 'X' (uppercase hexadecimal).
+// Format implements fmt.Formatter. It accepts the formats
+// 'b' (binary), 'o' (octal), 'd' (decimal), 'x' (lowercase
+// hexadecimal), and 'X' (uppercase hexadecimal).
 // Also supported are the full suite of package fmt's format
-// verbs for integral types, including '+', '-', and ' '
-// for sign control, '#' for leading zero in octal and for
-// hexadecimal, a leading "0x" or "0X" for "%#x" and "%#X"
-// respectively, specification of minimum digits precision,
-// output field width, space or zero padding, and left or
-// right justification.
+// flags for integral types, including '+' and ' ' for sign
+// control, '#' for leading zero in octal and for hexadecimal,
+// a leading "0x" or "0X" for "%#x" and "%#X" respectively,
+// specification of minimum digits precision, output field
+// width, space or zero padding, and '-' for left or right
+// justification.
 //
 func (x *Int) Format(s fmt.State, ch rune) {
 	// determine base
diff --git a/libgo/go/math/big/nat.go b/libgo/go/math/big/nat.go
index 79cf6e07f7f..2e65d2a7ef7 100644
--- a/libgo/go/math/big/nat.go
+++ b/libgo/go/math/big/nat.go
@@ -8,7 +8,10 @@
 
 package big
 
-import "math/rand"
+import (
+	"math/rand"
+	"sync"
+)
 
 // An unsigned integer x of the form
 //
@@ -539,6 +542,21 @@ func (z nat) div(z2, u, v nat) (q, r nat) {
 	return
 }
 
+// getNat returns a nat of len n. The contents may not be zero.
+func getNat(n int) nat {
+	var z nat
+	if v := natPool.Get(); v != nil {
+		z = v.(nat)
+	}
+	return z.make(n)
+}
+
+func putNat(x nat) {
+	natPool.Put(x)
+}
+
+var natPool sync.Pool
+
 // q = (uIn-r)/v, with 0 <= r < y
 // Uses z as storage for q, and u as storage for r if possible.
 // See Knuth, Volume 2, section 4.3.1, Algorithm D.
@@ -557,7 +575,7 @@ func (z nat) divLarge(u, uIn, v nat) (q, r nat) {
 	}
 	q = z.make(m + 1)
 
-	qhatv := make(nat, n+1)
+	qhatv := getNat(n + 1)
 	if alias(u, uIn) || alias(u, v) {
 		u = nil // u is an alias for uIn or v - cannot reuse
 	}
@@ -565,10 +583,11 @@ func (z nat) divLarge(u, uIn, v nat) (q, r nat) {
 	u.clear() // TODO(gri) no need to clear if we allocated a new u
 
 	// D1.
+	var v1 nat
 	shift := nlz(v[n-1])
 	if shift > 0 {
 		// do not modify v, it may be used by another goroutine simultaneously
-		v1 := make(nat, n)
+		v1 = getNat(n)
 		shlVU(v1, v, shift)
 		v = v1
 	}
@@ -609,6 +628,10 @@ func (z nat) divLarge(u, uIn, v nat) (q, r nat) {
 
 		q[j] = qhat
 	}
+	if v1 != nil {
+		putNat(v1)
+	}
+	putNat(qhatv)
 
 	q = q.norm()
 	shrVU(u, u, shift)
@@ -647,7 +670,7 @@ func trailingZeroBits(x Word) uint {
 	// x & -x leaves only the right-most bit set in the word. Let k be the
 	// index of that bit. Since only a single bit is set, the value is two
 	// to the power of k. Multiplying by a power of two is equivalent to
-	// left shifting, in this case by k bits.  The de Bruijn constant is
+	// left shifting, in this case by k bits. The de Bruijn constant is
 	// such that all six bit, consecutive substrings are distinct.
 	// Therefore, if we have a left shifted version of this constant we can
 	// find by how many bits it was shifted by looking at which six bit
@@ -1018,7 +1041,7 @@ func (z nat) expNNWindowed(x, y, m nat) nat {
 		for j := 0; j < _W; j += n {
 			if i != len(y)-1 || j != 0 {
 				// Unrolled loop for significant performance
-				// gain.  Use go test -bench=".*" in crypto/rsa
+				// gain. Use go test -bench=".*" in crypto/rsa
 				// to check performance before making changes.
 				zz = zz.mul(z, z)
 				zz, z = z, zz
diff --git a/libgo/go/math/big/nat_test.go b/libgo/go/math/big/nat_test.go
index 563ccb30523..ebb29856549 100644
--- a/libgo/go/math/big/nat_test.go
+++ b/libgo/go/math/big/nat_test.go
@@ -5,6 +5,7 @@
 package big
 
 import (
+	"fmt"
 	"runtime"
 	"strings"
 	"testing"
@@ -509,24 +510,20 @@ func TestExpNN(t *testing.T) {
 	}
 }
 
-func ExpHelper(b *testing.B, x, y Word) {
-	var z nat
-	for i := 0; i < b.N; i++ {
-		z.expWW(x, y)
+func BenchmarkExp3Power(b *testing.B) {
+	const x = 3
+	for _, y := range []Word{
+		0x10, 0x40, 0x100, 0x400, 0x1000, 0x4000, 0x10000, 0x40000, 0x100000, 0x400000,
+	} {
+		b.Run(fmt.Sprintf("%#x", y), func(b *testing.B) {
+			var z nat
+			for i := 0; i < b.N; i++ {
+				z.expWW(x, y)
+			}
+		})
 	}
 }
 
-func BenchmarkExp3Power0x10(b *testing.B)     { ExpHelper(b, 3, 0x10) }
-func BenchmarkExp3Power0x40(b *testing.B)     { ExpHelper(b, 3, 0x40) }
-func BenchmarkExp3Power0x100(b *testing.B)    { ExpHelper(b, 3, 0x100) }
-func BenchmarkExp3Power0x400(b *testing.B)    { ExpHelper(b, 3, 0x400) }
-func BenchmarkExp3Power0x1000(b *testing.B)   { ExpHelper(b, 3, 0x1000) }
-func BenchmarkExp3Power0x4000(b *testing.B)   { ExpHelper(b, 3, 0x4000) }
-func BenchmarkExp3Power0x10000(b *testing.B)  { ExpHelper(b, 3, 0x10000) }
-func BenchmarkExp3Power0x40000(b *testing.B)  { ExpHelper(b, 3, 0x40000) }
-func BenchmarkExp3Power0x100000(b *testing.B) { ExpHelper(b, 3, 0x100000) }
-func BenchmarkExp3Power0x400000(b *testing.B) { ExpHelper(b, 3, 0x400000) }
-
 func fibo(n int) nat {
 	switch n {
 	case 0:
diff --git a/libgo/go/math/big/natconv.go b/libgo/go/math/big/natconv.go
index d2ce667fb60..44547842c1c 100644
--- a/libgo/go/math/big/natconv.go
+++ b/libgo/go/math/big/natconv.go
@@ -302,7 +302,7 @@ func (x nat) itoa(neg bool, base int) []byte {
 		}
 
 	} else {
-		bb, ndigits := maxPow(Word(b))
+		bb, ndigits := maxPow(b)
 
 		// construct table of successive squares of bb*leafSize to use in subdivisions
 		// result (table != nil) <=> (len(x) > leafSize > 0)
@@ -391,7 +391,7 @@ func (q nat) convertWords(s []byte, b Word, ndigits int, bb Word, table []diviso
 				// this appears to be faster for BenchmarkString10000Base10
 				// and smaller strings (but a bit slower for larger ones)
 				t := r / 10
-				s[i] = '0' + byte(r-t<<3-t-t) // TODO(gri) replace w/ t*10 once compiler produces better code
+				s[i] = '0' + byte(r-t*10)
 				r = t
 			}
 		}
diff --git a/libgo/go/math/big/natconv_test.go b/libgo/go/math/big/natconv_test.go
index 028e5a858eb..79901d18804 100644
--- a/libgo/go/math/big/natconv_test.go
+++ b/libgo/go/math/big/natconv_test.go
@@ -6,6 +6,7 @@ package big
 
 import (
 	"bytes"
+	"fmt"
 	"io"
 	"strings"
 	"testing"
@@ -273,102 +274,58 @@ func BenchmarkStringPiParallel(b *testing.B) {
 	})
 }
 
-func BenchmarkScan10Base2(b *testing.B)     { ScanHelper(b, 2, 10, 10) }
-func BenchmarkScan100Base2(b *testing.B)    { ScanHelper(b, 2, 10, 100) }
-func BenchmarkScan1000Base2(b *testing.B)   { ScanHelper(b, 2, 10, 1000) }
-func BenchmarkScan10000Base2(b *testing.B)  { ScanHelper(b, 2, 10, 10000) }
-func BenchmarkScan100000Base2(b *testing.B) { ScanHelper(b, 2, 10, 100000) }
-
-func BenchmarkScan10Base8(b *testing.B)     { ScanHelper(b, 8, 10, 10) }
-func BenchmarkScan100Base8(b *testing.B)    { ScanHelper(b, 8, 10, 100) }
-func BenchmarkScan1000Base8(b *testing.B)   { ScanHelper(b, 8, 10, 1000) }
-func BenchmarkScan10000Base8(b *testing.B)  { ScanHelper(b, 8, 10, 10000) }
-func BenchmarkScan100000Base8(b *testing.B) { ScanHelper(b, 8, 10, 100000) }
-
-func BenchmarkScan10Base10(b *testing.B)     { ScanHelper(b, 10, 10, 10) }
-func BenchmarkScan100Base10(b *testing.B)    { ScanHelper(b, 10, 10, 100) }
-func BenchmarkScan1000Base10(b *testing.B)   { ScanHelper(b, 10, 10, 1000) }
-func BenchmarkScan10000Base10(b *testing.B)  { ScanHelper(b, 10, 10, 10000) }
-func BenchmarkScan100000Base10(b *testing.B) { ScanHelper(b, 10, 10, 100000) }
-
-func BenchmarkScan10Base16(b *testing.B)     { ScanHelper(b, 16, 10, 10) }
-func BenchmarkScan100Base16(b *testing.B)    { ScanHelper(b, 16, 10, 100) }
-func BenchmarkScan1000Base16(b *testing.B)   { ScanHelper(b, 16, 10, 1000) }
-func BenchmarkScan10000Base16(b *testing.B)  { ScanHelper(b, 16, 10, 10000) }
-func BenchmarkScan100000Base16(b *testing.B) { ScanHelper(b, 16, 10, 100000) }
-
-func ScanHelper(b *testing.B, base int, x, y Word) {
-	b.StopTimer()
-	var z nat
-	z = z.expWW(x, y)
-
-	s := z.utoa(base)
-	if t := itoa(z, base); !bytes.Equal(s, t) {
-		b.Fatalf("scanning: got %s; want %s", s, t)
+func BenchmarkScan(b *testing.B) {
+	const x = 10
+	for _, base := range []int{2, 8, 10, 16} {
+		for _, y := range []Word{10, 100, 1000, 10000, 100000} {
+			b.Run(fmt.Sprintf("%d/Base%d", y, base), func(b *testing.B) {
+				b.StopTimer()
+				var z nat
+				z = z.expWW(x, y)
+
+				s := z.utoa(base)
+				if t := itoa(z, base); !bytes.Equal(s, t) {
+					b.Fatalf("scanning: got %s; want %s", s, t)
+				}
+				b.StartTimer()
+
+				for i := 0; i < b.N; i++ {
+					z.scan(bytes.NewReader(s), base, false)
+				}
+			})
+		}
 	}
-	b.StartTimer()
+}
 
-	for i := 0; i < b.N; i++ {
-		z.scan(bytes.NewReader(s), base, false)
+func BenchmarkString(b *testing.B) {
+	const x = 10
+	for _, base := range []int{2, 8, 10, 16} {
+		for _, y := range []Word{10, 100, 1000, 10000, 100000} {
+			b.Run(fmt.Sprintf("%d/Base%d", y, base), func(b *testing.B) {
+				b.StopTimer()
+				var z nat
+				z = z.expWW(x, y)
+				z.utoa(base) // warm divisor cache
+				b.StartTimer()
+
+				for i := 0; i < b.N; i++ {
+					_ = z.utoa(base)
+				}
+			})
+		}
 	}
 }
 
-func BenchmarkString10Base2(b *testing.B)     { StringHelper(b, 2, 10, 10) }
-func BenchmarkString100Base2(b *testing.B)    { StringHelper(b, 2, 10, 100) }
-func BenchmarkString1000Base2(b *testing.B)   { StringHelper(b, 2, 10, 1000) }
-func BenchmarkString10000Base2(b *testing.B)  { StringHelper(b, 2, 10, 10000) }
-func BenchmarkString100000Base2(b *testing.B) { StringHelper(b, 2, 10, 100000) }
-
-func BenchmarkString10Base8(b *testing.B)     { StringHelper(b, 8, 10, 10) }
-func BenchmarkString100Base8(b *testing.B)    { StringHelper(b, 8, 10, 100) }
-func BenchmarkString1000Base8(b *testing.B)   { StringHelper(b, 8, 10, 1000) }
-func BenchmarkString10000Base8(b *testing.B)  { StringHelper(b, 8, 10, 10000) }
-func BenchmarkString100000Base8(b *testing.B) { StringHelper(b, 8, 10, 100000) }
-
-func BenchmarkString10Base10(b *testing.B)     { StringHelper(b, 10, 10, 10) }
-func BenchmarkString100Base10(b *testing.B)    { StringHelper(b, 10, 10, 100) }
-func BenchmarkString1000Base10(b *testing.B)   { StringHelper(b, 10, 10, 1000) }
-func BenchmarkString10000Base10(b *testing.B)  { StringHelper(b, 10, 10, 10000) }
-func BenchmarkString100000Base10(b *testing.B) { StringHelper(b, 10, 10, 100000) }
-
-func BenchmarkString10Base16(b *testing.B)     { StringHelper(b, 16, 10, 10) }
-func BenchmarkString100Base16(b *testing.B)    { StringHelper(b, 16, 10, 100) }
-func BenchmarkString1000Base16(b *testing.B)   { StringHelper(b, 16, 10, 1000) }
-func BenchmarkString10000Base16(b *testing.B)  { StringHelper(b, 16, 10, 10000) }
-func BenchmarkString100000Base16(b *testing.B) { StringHelper(b, 16, 10, 100000) }
-
-func StringHelper(b *testing.B, base int, x, y Word) {
-	b.StopTimer()
-	var z nat
-	z = z.expWW(x, y)
-	z.utoa(base) // warm divisor cache
-	b.StartTimer()
-
-	for i := 0; i < b.N; i++ {
-		_ = z.utoa(base)
+func BenchmarkLeafSize(b *testing.B) {
+	for n := 0; n <= 16; n++ {
+		b.Run(fmt.Sprint(n), func(b *testing.B) { LeafSizeHelper(b, 10, n) })
+	}
+	// Try some large lengths
+	for _, n := range []int{32, 64} {
+		b.Run(fmt.Sprint(n), func(b *testing.B) { LeafSizeHelper(b, 10, n) })
 	}
 }
 
-func BenchmarkLeafSize0(b *testing.B)  { LeafSizeHelper(b, 10, 0) } // test without splitting
-func BenchmarkLeafSize1(b *testing.B)  { LeafSizeHelper(b, 10, 1) }
-func BenchmarkLeafSize2(b *testing.B)  { LeafSizeHelper(b, 10, 2) }
-func BenchmarkLeafSize3(b *testing.B)  { LeafSizeHelper(b, 10, 3) }
-func BenchmarkLeafSize4(b *testing.B)  { LeafSizeHelper(b, 10, 4) }
-func BenchmarkLeafSize5(b *testing.B)  { LeafSizeHelper(b, 10, 5) }
-func BenchmarkLeafSize6(b *testing.B)  { LeafSizeHelper(b, 10, 6) }
-func BenchmarkLeafSize7(b *testing.B)  { LeafSizeHelper(b, 10, 7) }
-func BenchmarkLeafSize8(b *testing.B)  { LeafSizeHelper(b, 10, 8) }
-func BenchmarkLeafSize9(b *testing.B)  { LeafSizeHelper(b, 10, 9) }
-func BenchmarkLeafSize10(b *testing.B) { LeafSizeHelper(b, 10, 10) }
-func BenchmarkLeafSize11(b *testing.B) { LeafSizeHelper(b, 10, 11) }
-func BenchmarkLeafSize12(b *testing.B) { LeafSizeHelper(b, 10, 12) }
-func BenchmarkLeafSize13(b *testing.B) { LeafSizeHelper(b, 10, 13) }
-func BenchmarkLeafSize14(b *testing.B) { LeafSizeHelper(b, 10, 14) }
-func BenchmarkLeafSize15(b *testing.B) { LeafSizeHelper(b, 10, 15) }
-func BenchmarkLeafSize16(b *testing.B) { LeafSizeHelper(b, 10, 16) }
-func BenchmarkLeafSize32(b *testing.B) { LeafSizeHelper(b, 10, 32) } // try some large lengths
-func BenchmarkLeafSize64(b *testing.B) { LeafSizeHelper(b, 10, 64) }
-
 func LeafSizeHelper(b *testing.B, base, size int) {
 	b.StopTimer()
 	originalLeafSize := leafSize
diff --git a/libgo/go/math/big/rat.go b/libgo/go/math/big/rat.go
index 2cd9ed09388..56ce33d8826 100644
--- a/libgo/go/math/big/rat.go
+++ b/libgo/go/math/big/rat.go
@@ -63,7 +63,7 @@ func (z *Rat) SetFloat64(f float64) *Rat {
 
 // quotToFloat32 returns the non-negative float32 value
 // nearest to the quotient a/b, using round-to-even in
-// halfway cases.  It does not mutate its arguments.
+// halfway cases. It does not mutate its arguments.
 // Preconditions: b is non-zero; a and b have no common factors.
 func quotToFloat32(a, b nat) (f float32, exact bool) {
 	const (
@@ -161,7 +161,7 @@ func quotToFloat32(a, b nat) (f float32, exact bool) {
 
 // quotToFloat64 returns the non-negative float64 value
 // nearest to the quotient a/b, using round-to-even in
-// halfway cases.  It does not mutate its arguments.
+// halfway cases. It does not mutate its arguments.
 // Preconditions: b is non-zero; a and b have no common factors.
 func quotToFloat64(a, b nat) (f float64, exact bool) {
 	const (
diff --git a/libgo/go/math/big/ratconv.go b/libgo/go/math/big/ratconv.go
index 4566ff4e39d..ef2b6750d0c 100644
--- a/libgo/go/math/big/ratconv.go
+++ b/libgo/go/math/big/ratconv.go
@@ -15,7 +15,7 @@ import (
 )
 
 func ratTok(ch rune) bool {
-	return strings.IndexRune("+-/0123456789.eE", ch) >= 0
+	return strings.ContainsRune("+-/0123456789.eE", ch)
 }
 
 // Scan is a support routine for fmt.Scanner. It accepts the formats
@@ -25,7 +25,7 @@ func (z *Rat) Scan(s fmt.ScanState, ch rune) error {
 	if err != nil {
 		return err
 	}
-	if strings.IndexRune("efgEFGv", ch) < 0 {
+	if !strings.ContainsRune("efgEFGv", ch) {
 		return errors.New("Rat.Scan: invalid verb")
 	}
 	if _, ok := z.SetString(string(tok)); !ok {
@@ -88,6 +88,12 @@ func (z *Rat) SetString(s string) (*Rat, bool) {
 		return nil, false
 	}
 
+	// special-case 0 (see also issue #16176)
+	if len(z.a.abs) == 0 {
+		return z, true
+	}
+	// len(z.a.abs) > 0
+
 	// correct exponent
 	if ecorr < 0 {
 		exp += int64(ecorr)
@@ -178,7 +184,7 @@ func scanExponent(r io.ByteScanner, binExpOk bool) (exp int64, base int, err err
 			}
 			break // i > 0
 		}
-		digits = append(digits, byte(ch))
+		digits = append(digits, ch)
 	}
 	// i > 0 => we have at least one digit
 
diff --git a/libgo/go/math/big/ratconv_test.go b/libgo/go/math/big/ratconv_test.go
index da2fdab4cab..35ad6ccea77 100644
--- a/libgo/go/math/big/ratconv_test.go
+++ b/libgo/go/math/big/ratconv_test.go
@@ -48,6 +48,7 @@ var setStringTests = []StringTest{
 	{"53/70893980658822810696", "53/70893980658822810696", true},
 	{"106/141787961317645621392", "53/70893980658822810696", true},
 	{"204211327800791583.81095", "4084226556015831676219/20000", true},
+	{"0e9999999999", "0", true}, // issue #16176
 	{in: "1/0"},
 }
 
@@ -137,7 +138,7 @@ func TestFloatString(t *testing.T) {
 	}
 }
 
-// Test inputs to Rat.SetString.  The prefix "long:" causes the test
+// Test inputs to Rat.SetString. The prefix "long:" causes the test
 // to be skipped in --test.short mode.  (The threshold is about 500us.)
 var float64inputs = []string{
 	// Constants plundered from strconv/testfp.txt.
diff --git a/libgo/go/math/cmplx/cmath_test.go b/libgo/go/math/cmplx/cmath_test.go
index 18d9be81948..d904be880d8 100644
--- a/libgo/go/math/cmplx/cmath_test.go
+++ b/libgo/go/math/cmplx/cmath_test.go
@@ -9,6 +9,9 @@ import (
 	"testing"
 )
 
+// The higher-precision values in vc26 were used to derive the
+// input arguments vc (see also comment below). For reference
+// only (do not delete).
 var vc26 = []complex128{
 	(4.97901192488367350108546816 + 7.73887247457810456552351752i),
 	(7.73887247457810456552351752 - 0.27688005719200159404635997i),
@@ -21,6 +24,7 @@ var vc26 = []complex128{
 	(1.82530809168085506044576505 - 8.68592476857560136238589621i),
 	(-8.68592476857560136238589621 + 4.97901192488367350108546816i),
 }
+
 var vc = []complex128{
 	(4.9790119248836735e+00 + 7.7388724745781045e+00i),
 	(7.7388724745781045e+00 - 2.7688005719200159e-01i),
@@ -448,8 +452,7 @@ func tolerance(a, b, e float64) bool {
 	}
 	return d < e
 }
-func soclose(a, b, e float64) bool { return tolerance(a, b, e) }
-func veryclose(a, b float64) bool  { return tolerance(a, b, 4e-16) }
+func veryclose(a, b float64) bool { return tolerance(a, b, 4e-16) }
 func alike(a, b float64) bool {
 	switch {
 	case a != a && b != b: // math.IsNaN(a) && math.IsNaN(b):
diff --git a/libgo/go/math/cmplx/sqrt.go b/libgo/go/math/cmplx/sqrt.go
index 276be07ae9a..72f81e907cf 100644
--- a/libgo/go/math/cmplx/sqrt.go
+++ b/libgo/go/math/cmplx/sqrt.go
@@ -43,7 +43,7 @@ import "math"
 // Cancelation error in r-x or r+x is avoided by using the
 // identity  2 Re w Im w  =  y.
 //
-// Note that -w is also a square root of z.  The root chosen
+// Note that -w is also a square root of z. The root chosen
 // is always in the right half plane and Im w has the same sign as y.
 //
 // ACCURACY:
diff --git a/libgo/go/math/erf.go b/libgo/go/math/erf.go
index 4cd80f80c3b..8ddd5f9809d 100644
--- a/libgo/go/math/erf.go
+++ b/libgo/go/math/erf.go
@@ -10,7 +10,7 @@ package math
 
 // The original C code and the long comment below are
 // from FreeBSD's /usr/src/lib/msun/src/s_erf.c and
-// came with this notice.  The go code is a simplified
+// came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/exp.go b/libgo/go/math/exp.go
index 51330c21dc8..cbc955d01e4 100644
--- a/libgo/go/math/exp.go
+++ b/libgo/go/math/exp.go
@@ -21,7 +21,7 @@ func Exp(x float64) float64 {
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/e_exp.c
-// and came with this notice.  The go code is a simplified
+// and came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/expm1.go b/libgo/go/math/expm1.go
index b4dcdc52a20..5a962180e5d 100644
--- a/libgo/go/math/expm1.go
+++ b/libgo/go/math/expm1.go
@@ -6,7 +6,7 @@ package math
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/s_expm1.c
-// and came with this notice.  The go code is a simplified
+// and came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/export_test.go b/libgo/go/math/export_test.go
index 02992d70e84..368308e1e5d 100644
--- a/libgo/go/math/export_test.go
+++ b/libgo/go/math/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/math/gamma.go b/libgo/go/math/gamma.go
index 164f54f332b..841ec114a0a 100644
--- a/libgo/go/math/gamma.go
+++ b/libgo/go/math/gamma.go
@@ -21,7 +21,7 @@ package math
 //
 // DESCRIPTION:
 //
-// Returns gamma function of the argument.  The result is
+// Returns gamma function of the argument. The result is
 // correctly signed, and the sign (+1 or -1) is also
 // returned in a global (extern) variable named signgam.
 // This variable is also filled in by the logarithmic gamma
diff --git a/libgo/go/math/j0.go b/libgo/go/math/j0.go
index de7738880e6..cbef7aa7d6e 100644
--- a/libgo/go/math/j0.go
+++ b/libgo/go/math/j0.go
@@ -10,7 +10,7 @@ package math
 
 // The original C code and the long comment below are
 // from FreeBSD's /usr/src/lib/msun/src/e_j0.c and
-// came with this notice.  The go code is a simplified
+// came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/j1.go b/libgo/go/math/j1.go
index c537a72eb25..d359d9072e3 100644
--- a/libgo/go/math/j1.go
+++ b/libgo/go/math/j1.go
@@ -10,7 +10,7 @@ package math
 
 // The original C code and the long comment below are
 // from FreeBSD's /usr/src/lib/msun/src/e_j1.c and
-// came with this notice.  The go code is a simplified
+// came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/jn.go b/libgo/go/math/jn.go
index ffb8a00f50f..721112f77c4 100644
--- a/libgo/go/math/jn.go
+++ b/libgo/go/math/jn.go
@@ -10,7 +10,7 @@ package math
 
 // The original C code and the long comment below are
 // from FreeBSD's /usr/src/lib/msun/src/e_jn.c and
-// came with this notice.  The go code is a simplified
+// came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/lgamma.go b/libgo/go/math/lgamma.go
index 6a02c412d93..19ac3ffafca 100644
--- a/libgo/go/math/lgamma.go
+++ b/libgo/go/math/lgamma.go
@@ -10,7 +10,7 @@ package math
 
 // The original C code and the long comment below are
 // from FreeBSD's /usr/src/lib/msun/src/e_lgamma_r.c and
-// came with this notice.  The go code is a simplified
+// came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/log.go b/libgo/go/math/log.go
index 60b57552d8b..cf242e86fdd 100644
--- a/libgo/go/math/log.go
+++ b/libgo/go/math/log.go
@@ -10,7 +10,7 @@ package math
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/e_log.c
-// and came with this notice.  The go code is a simpler
+// and came with this notice. The go code is a simpler
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/log1p.go b/libgo/go/math/log1p.go
index c8daaaa1c95..6834caedcef 100644
--- a/libgo/go/math/log1p.go
+++ b/libgo/go/math/log1p.go
@@ -6,7 +6,7 @@ package math
 
 // The original C code, the long comment, and the constants
 // below are from FreeBSD's /usr/src/lib/msun/src/s_log1p.c
-// and came with this notice.  The go code is a simplified
+// and came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/modf.go b/libgo/go/math/modf.go
index 5d2f489b709..b59d4b7fd5a 100644
--- a/libgo/go/math/modf.go
+++ b/libgo/go/math/modf.go
@@ -5,7 +5,7 @@
 package math
 
 // Modf returns integer and fractional floating-point numbers
-// that sum to f.  Both values have the same sign as f.
+// that sum to f. Both values have the same sign as f.
 //
 // Special cases are:
 //	Modf(±Inf) = ±Inf, NaN
diff --git a/libgo/go/math/rand/race_test.go b/libgo/go/math/rand/race_test.go
new file mode 100644
index 00000000000..48f6c290b98
--- /dev/null
+++ b/libgo/go/math/rand/race_test.go
@@ -0,0 +1,47 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package rand
+
+import (
+	"sync"
+	"testing"
+)
+
+// TestConcurrent exercises the rand API concurrently, triggering situations
+// where the race detector is likely to detect issues.
+func TestConcurrent(t *testing.T) {
+	const (
+		numRoutines = 10
+		numCycles   = 10
+	)
+	var wg sync.WaitGroup
+	defer wg.Wait()
+	wg.Add(numRoutines)
+	for i := 0; i < numRoutines; i++ {
+		go func(i int) {
+			defer wg.Done()
+			buf := make([]byte, 997)
+			for j := 0; j < numCycles; j++ {
+				var seed int64
+				seed += int64(ExpFloat64())
+				seed += int64(Float32())
+				seed += int64(Float64())
+				seed += int64(Intn(Int()))
+				seed += int64(Int31n(Int31()))
+				seed += int64(Int63n(Int63()))
+				seed += int64(NormFloat64())
+				seed += int64(Uint32())
+				for _, p := range Perm(10) {
+					seed += int64(p)
+				}
+				Read(buf)
+				for _, b := range buf {
+					seed += int64(b)
+				}
+				Seed(int64(i*j) * seed)
+			}
+		}(i)
+	}
+}
diff --git a/libgo/go/math/rand/rand.go b/libgo/go/math/rand/rand.go
index d693bfb52f2..dd8d43cca1c 100644
--- a/libgo/go/math/rand/rand.go
+++ b/libgo/go/math/rand/rand.go
@@ -33,14 +33,32 @@ func NewSource(seed int64) Source {
 // A Rand is a source of random numbers.
 type Rand struct {
 	src Source
+
+	// readVal contains remainder of 63-bit integer used for bytes
+	// generation during most recent Read call.
+	// It is saved so next Read call can start where the previous
+	// one finished.
+	readVal int64
+	// readPos indicates the number of low-order bytes of readVal
+	// that are still valid.
+	readPos int8
 }
 
 // New returns a new Rand that uses random values from src
 // to generate other random values.
-func New(src Source) *Rand { return &Rand{src} }
+func New(src Source) *Rand { return &Rand{src: src} }
 
 // Seed uses the provided seed value to initialize the generator to a deterministic state.
-func (r *Rand) Seed(seed int64) { r.src.Seed(seed) }
+// Seed should not be called concurrently with any other Rand method.
+func (r *Rand) Seed(seed int64) {
+	if lk, ok := r.src.(*lockedSource); ok {
+		lk.seedPos(seed, &r.readPos)
+		return
+	}
+
+	r.src.Seed(seed)
+	r.readPos = 0
+}
 
 // Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
 func (r *Rand) Int63() int64 { return r.src.Int63() }
@@ -160,15 +178,29 @@ func (r *Rand) Perm(n int) []int {
 
 // Read generates len(p) random bytes and writes them into p. It
 // always returns len(p) and a nil error.
+// Read should not be called concurrently with any other Rand method.
 func (r *Rand) Read(p []byte) (n int, err error) {
-	for i := 0; i < len(p); i += 7 {
-		val := r.src.Int63()
-		for j := 0; i+j < len(p) && j < 7; j++ {
-			p[i+j] = byte(val)
-			val >>= 8
+	if lk, ok := r.src.(*lockedSource); ok {
+		return lk.read(p, &r.readVal, &r.readPos)
+	}
+	return read(p, r.Int63, &r.readVal, &r.readPos)
+}
+
+func read(p []byte, int63 func() int64, readVal *int64, readPos *int8) (n int, err error) {
+	pos := *readPos
+	val := *readVal
+	for n = 0; n < len(p); n++ {
+		if pos == 0 {
+			val = int63()
+			pos = 7
 		}
+		p[n] = byte(val)
+		val >>= 8
+		pos--
 	}
-	return len(p), nil
+	*readPos = pos
+	*readVal = val
+	return
 }
 
 /*
@@ -179,7 +211,9 @@ var globalRand = New(&lockedSource{src: NewSource(1)})
 
 // Seed uses the provided seed value to initialize the default Source to a
 // deterministic state. If Seed is not called, the generator behaves as
-// if seeded by Seed(1).
+// if seeded by Seed(1). Seed values that have the same remainder when
+// divided by 2^31-1 generate the same pseudo-random sequence.
+// Seed, unlike the Rand.Seed method, is safe for concurrent use.
 func Seed(seed int64) { globalRand.Seed(seed) }
 
 // Int63 returns a non-negative pseudo-random 63-bit integer as an int64
@@ -226,6 +260,7 @@ func Perm(n int) []int { return globalRand.Perm(n) }
 
 // Read generates len(p) random bytes from the default Source and
 // writes them into p. It always returns len(p) and a nil error.
+// Read, unlike the Rand.Read method, is safe for concurrent use.
 func Read(p []byte) (n int, err error) { return globalRand.Read(p) }
 
 // NormFloat64 returns a normally distributed float64 in the range
@@ -266,3 +301,19 @@ func (r *lockedSource) Seed(seed int64) {
 	r.src.Seed(seed)
 	r.lk.Unlock()
 }
+
+// seedPos implements Seed for a lockedSource without a race condiiton.
+func (r *lockedSource) seedPos(seed int64, readPos *int8) {
+	r.lk.Lock()
+	r.src.Seed(seed)
+	*readPos = 0
+	r.lk.Unlock()
+}
+
+// read implements Read for a lockedSource without a race condition.
+func (r *lockedSource) read(p []byte, readVal *int64, readPos *int8) (n int, err error) {
+	r.lk.Lock()
+	n, err = read(p, r.src.Int63, readVal, readPos)
+	r.lk.Unlock()
+	return
+}
diff --git a/libgo/go/math/rand/rand_test.go b/libgo/go/math/rand/rand_test.go
index 8d68335fdd4..6f312792d0b 100644
--- a/libgo/go/math/rand/rand_test.go
+++ b/libgo/go/math/rand/rand_test.go
@@ -5,13 +5,16 @@
 package rand
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"internal/testenv"
+	"io"
 	"math"
 	"os"
 	"runtime"
 	"testing"
+	"testing/iotest"
 )
 
 const (
@@ -373,7 +376,7 @@ func testReadUniformity(t *testing.T, n int, seed int64) {
 	checkSampleDistribution(t, samples, expected)
 }
 
-func TestRead(t *testing.T) {
+func TestReadUniformity(t *testing.T) {
 	testBufferSizes := []int{
 		2, 4, 7, 64, 1024, 1 << 16, 1 << 20,
 	}
@@ -394,7 +397,42 @@ func TestReadEmpty(t *testing.T) {
 	if n != 0 {
 		t.Errorf("Read into empty buffer returned unexpected n of %d", n)
 	}
+}
+
+func TestReadByOneByte(t *testing.T) {
+	r := New(NewSource(1))
+	b1 := make([]byte, 100)
+	_, err := io.ReadFull(iotest.OneByteReader(r), b1)
+	if err != nil {
+		t.Errorf("read by one byte: %v", err)
+	}
+	r = New(NewSource(1))
+	b2 := make([]byte, 100)
+	_, err = r.Read(b2)
+	if err != nil {
+		t.Errorf("read: %v", err)
+	}
+	if !bytes.Equal(b1, b2) {
+		t.Errorf("read by one byte vs single read:\n%x\n%x", b1, b2)
+	}
+}
 
+func TestReadSeedReset(t *testing.T) {
+	r := New(NewSource(42))
+	b1 := make([]byte, 128)
+	_, err := r.Read(b1)
+	if err != nil {
+		t.Errorf("read: %v", err)
+	}
+	r.Seed(42)
+	b2 := make([]byte, 128)
+	_, err = r.Read(b2)
+	if err != nil {
+		t.Errorf("read: %v", err)
+	}
+	if !bytes.Equal(b1, b2) {
+		t.Errorf("mismatch after re-seed:\n%x\n%x", b1, b2)
+	}
 }
 
 // Benchmarks
diff --git a/libgo/go/math/rand/regress_test.go b/libgo/go/math/rand/regress_test.go
index 9ae53574478..4dd965ce1e3 100644
--- a/libgo/go/math/rand/regress_test.go
+++ b/libgo/go/math/rand/regress_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -342,25 +342,25 @@ var regressGolden = []interface{}{
 	[]int{8, 7, 5, 3, 4, 6, 0, 1, 2},    // Perm(9)
 	[]int{1, 0, 2, 5, 7, 6, 9, 8, 3, 4}, // Perm(10)
 	[]byte{0x1},                         // Read([0])
-	[]byte{0xc0, 0x41, 0xd3, 0xff, 0x12, 0x4, 0x5b},                   // Read([0 0 0 0 0 0 0])
-	[]byte{0x73, 0xc8, 0x6e, 0x4f, 0xf9, 0x5f, 0xf6, 0x62},            // Read([0 0 0 0 0 0 0 0])
-	[]byte{0x4a, 0x2d, 0xb, 0x75, 0xfb, 0x18, 0xd, 0xaf, 0x48},        // Read([0 0 0 0 0 0 0 0 0])
-	[]byte{0x39, 0x46, 0x51, 0x85, 0xf, 0xd4, 0xa1, 0x78, 0x89, 0x2e}, // Read([0 0 0 0 0 0 0 0 0 0])
-	[]byte{0x51}, // Read([0])
-	[]byte{0x4e, 0xe2, 0xd3, 0xd0, 0xd0, 0xde, 0x6b},                   // Read([0 0 0 0 0 0 0])
-	[]byte{0xf8, 0xf9, 0xb4, 0x4c, 0xe8, 0x5f, 0xf0, 0x44},             // Read([0 0 0 0 0 0 0 0])
-	[]byte{0x3b, 0xbf, 0x85, 0x7a, 0xab, 0x99, 0xc5, 0xb2, 0x52},       // Read([0 0 0 0 0 0 0 0 0])
-	[]byte{0xa8, 0xae, 0xb7, 0x9e, 0xf8, 0x56, 0xf6, 0x59, 0xc1, 0x8f}, // Read([0 0 0 0 0 0 0 0 0 0])
-	[]byte{0xc7}, // Read([0])
-	[]byte{0x5f, 0x67, 0xcf, 0xe2, 0x42, 0xcf, 0x3c},                   // Read([0 0 0 0 0 0 0])
-	[]byte{0xc3, 0x54, 0xf3, 0xed, 0xe2, 0xd6, 0xbe, 0xcc},             // Read([0 0 0 0 0 0 0 0])
-	[]byte{0x6a, 0x9f, 0x4a, 0x57, 0x8b, 0xcb, 0x9e, 0xf2, 0xd4},       // Read([0 0 0 0 0 0 0 0 0])
-	[]byte{0x6d, 0x29, 0x97, 0x61, 0xea, 0x9e, 0x4f, 0x5a, 0xa6, 0xae}, // Read([0 0 0 0 0 0 0 0 0 0])
-	[]byte{0xaa}, // Read([0])
-	[]byte{0x20, 0xef, 0xcd, 0x6c, 0xea, 0x84, 0xb6},                   // Read([0 0 0 0 0 0 0])
-	[]byte{0x92, 0x5e, 0x60, 0x7b, 0xe0, 0x63, 0x71, 0x6f},             // Read([0 0 0 0 0 0 0 0])
-	[]byte{0x4, 0x5c, 0x3f, 0x0, 0xf, 0x8a, 0x79, 0x6b, 0xce},          // Read([0 0 0 0 0 0 0 0 0])
-	[]byte{0xaa, 0xca, 0xee, 0xdf, 0xad, 0x5b, 0x50, 0x66, 0x64, 0xe8}, // Read([0 0 0 0 0 0 0 0 0 0])
+	[]byte{0x94, 0xfd, 0xc2, 0xfa, 0x2f, 0xfc, 0xc0},                 // Read([0 0 0 0 0 0 0])
+	[]byte{0x41, 0xd3, 0xff, 0x12, 0x4, 0x5b, 0x73, 0xc8},            // Read([0 0 0 0 0 0 0 0])
+	[]byte{0x6e, 0x4f, 0xf9, 0x5f, 0xf6, 0x62, 0xa5, 0xee, 0xe8},     // Read([0 0 0 0 0 0 0 0 0])
+	[]byte{0x2a, 0xbd, 0xf4, 0x4a, 0x2d, 0xb, 0x75, 0xfb, 0x18, 0xd}, // Read([0 0 0 0 0 0 0 0 0 0])
+	[]byte{0xaf},                                                      // Read([0])
+	[]byte{0x48, 0xa7, 0x9e, 0xe0, 0xb1, 0xd, 0x39},                   // Read([0 0 0 0 0 0 0])
+	[]byte{0x46, 0x51, 0x85, 0xf, 0xd4, 0xa1, 0x78, 0x89},             // Read([0 0 0 0 0 0 0 0])
+	[]byte{0x2e, 0xe2, 0x85, 0xec, 0xe1, 0x51, 0x14, 0x55, 0x78},      // Read([0 0 0 0 0 0 0 0 0])
+	[]byte{0x8, 0x75, 0xd6, 0x4e, 0xe2, 0xd3, 0xd0, 0xd0, 0xde, 0x6b}, // Read([0 0 0 0 0 0 0 0 0 0])
+	[]byte{0xf8}, // Read([0])
+	[]byte{0xf9, 0xb4, 0x4c, 0xe8, 0x5f, 0xf0, 0x44},                   // Read([0 0 0 0 0 0 0])
+	[]byte{0xc6, 0xb1, 0xf8, 0x3b, 0x8e, 0x88, 0x3b, 0xbf},             // Read([0 0 0 0 0 0 0 0])
+	[]byte{0x85, 0x7a, 0xab, 0x99, 0xc5, 0xb2, 0x52, 0xc7, 0x42},       // Read([0 0 0 0 0 0 0 0 0])
+	[]byte{0x9c, 0x32, 0xf3, 0xa8, 0xae, 0xb7, 0x9e, 0xf8, 0x56, 0xf6}, // Read([0 0 0 0 0 0 0 0 0 0])
+	[]byte{0x59},                                                       // Read([0])
+	[]byte{0xc1, 0x8f, 0xd, 0xce, 0xcc, 0x77, 0xc7},                    // Read([0 0 0 0 0 0 0])
+	[]byte{0x5e, 0x7a, 0x81, 0xbf, 0xde, 0x27, 0x5f, 0x67},             // Read([0 0 0 0 0 0 0 0])
+	[]byte{0xcf, 0xe2, 0x42, 0xcf, 0x3c, 0xc3, 0x54, 0xf3, 0xed},       // Read([0 0 0 0 0 0 0 0 0])
+	[]byte{0xe2, 0xd6, 0xbe, 0xcc, 0x4e, 0xa3, 0xae, 0x5e, 0x88, 0x52}, // Read([0 0 0 0 0 0 0 0 0 0])
 	uint32(4059586549),                                                 // Uint32()
 	uint32(1052117029),                                                 // Uint32()
 	uint32(2817310706),                                                 // Uint32()
diff --git a/libgo/go/math/remainder.go b/libgo/go/math/remainder.go
index 98bb04dc794..c6a4c7d741d 100644
--- a/libgo/go/math/remainder.go
+++ b/libgo/go/math/remainder.go
@@ -6,7 +6,7 @@ package math
 
 // The original C code and the comment below are from
 // FreeBSD's /usr/src/lib/msun/src/e_remainder.c and came
-// with this notice.  The go code is a simplified version of
+// with this notice. The go code is a simplified version of
 // the original C.
 //
 // ====================================================
diff --git a/libgo/go/math/sqrt.go b/libgo/go/math/sqrt.go
index 86c04523478..c65c32e8a01 100644
--- a/libgo/go/math/sqrt.go
+++ b/libgo/go/math/sqrt.go
@@ -13,7 +13,7 @@ func Sqrt(x float64) float64 {
 
 // The original C code and the long comment below are
 // from FreeBSD's /usr/src/lib/msun/src/e_sqrt.c and
-// came with this notice.  The go code is a simplified
+// came with this notice. The go code is a simplified
 // version of the original C.
 //
 // ====================================================
@@ -86,7 +86,7 @@ func Sqrt(x float64) float64 {
 //      equal to huge for some floating point number "huge" and "tiny".
 //
 //
-// Notes:  Rounding mode detection omitted.  The constants "mask", "shift",
+// Notes:  Rounding mode detection omitted. The constants "mask", "shift",
 // and "bias" are found in src/math/bits.go
 
 // Sqrt returns the square root of x.
@@ -148,7 +148,3 @@ func sqrt(x float64) float64 {
 	ix = q>>1 + uint64(exp-1+bias)<<shift // significand + biased exponent
 	return Float64frombits(ix)
 }
-
-func sqrtC(f float64, r *float64) {
-	*r = sqrt(f)
-}
diff --git a/libgo/go/mime/encodedword.go b/libgo/go/mime/encodedword.go
index db4b5f4510b..c3ca4bacd13 100644
--- a/libgo/go/mime/encodedword.go
+++ b/libgo/go/mime/encodedword.go
@@ -16,7 +16,7 @@ import (
 	"unicode/utf8"
 )
 
-// A WordEncoder is a RFC 2047 encoded-word encoder.
+// A WordEncoder is an RFC 2047 encoded-word encoder.
 type WordEncoder byte
 
 const (
@@ -71,7 +71,7 @@ const (
 	maxEncodedWordLen = 75
 	// maxContentLen is how much content can be encoded, ignoring the header and
 	// 2-byte footer.
-	maxContentLen = maxEncodedWordLen - len("=?UTF-8?") - len("?=")
+	maxContentLen = maxEncodedWordLen - len("=?UTF-8?q?") - len("?=")
 )
 
 var maxBase64Len = base64.StdEncoding.DecodedLen(maxContentLen)
@@ -89,7 +89,7 @@ func (e WordEncoder) bEncode(buf *bytes.Buffer, charset, s string) {
 
 	var currentLen, last, runeLen int
 	for i := 0; i < len(s); i += runeLen {
-		// Multi-byte characters must not be split accross encoded-words.
+		// Multi-byte characters must not be split across encoded-words.
 		// See RFC 2047, section 5.3.
 		_, runeLen = utf8.DecodeRuneInString(s[i:])
 
@@ -119,7 +119,7 @@ func (e WordEncoder) qEncode(buf *bytes.Buffer, charset, s string) {
 	var currentLen, runeLen int
 	for i := 0; i < len(s); i += runeLen {
 		b := s[i]
-		// Multi-byte characters must not be split accross encoded-words.
+		// Multi-byte characters must not be split across encoded-words.
 		// See RFC 2047, section 5.3.
 		var encLen int
 		if b >= ' ' && b <= '~' && b != '=' && b != '?' && b != '_' {
diff --git a/libgo/go/mime/encodedword_test.go b/libgo/go/mime/encodedword_test.go
index 5fcd7a06dd6..b7ca4d05e3a 100644
--- a/libgo/go/mime/encodedword_test.go
+++ b/libgo/go/mime/encodedword_test.go
@@ -31,10 +31,8 @@ func TestEncodeWord(t *testing.T) {
 		{QEncoding, utf8, strings.Repeat("é", 11), "=?utf-8?q?" + strings.Repeat("=C3=A9", 10) + "?= =?utf-8?q?=C3=A9?="},
 		{QEncoding, iso88591, strings.Repeat("\xe9", 22), "=?iso-8859-1?q?" + strings.Repeat("=E9", 22) + "?="},
 		{QEncoding, utf8, strings.Repeat("\x80", 22), "=?utf-8?q?" + strings.Repeat("=80", 21) + "?= =?utf-8?q?=80?="},
-		{BEncoding, utf8, strings.Repeat("é", 24), "=?utf-8?b?" + strings.Repeat("w6nDqcOp", 8) + "?="},
-		{BEncoding, utf8, strings.Repeat("é", 27), "=?utf-8?b?" + strings.Repeat("w6nDqcOp", 8) + "?= =?utf-8?b?w6nDqcOp?="},
 		{BEncoding, iso88591, strings.Repeat("\xe9", 45), "=?iso-8859-1?b?" + strings.Repeat("6enp", 15) + "?="},
-		{BEncoding, utf8, strings.Repeat("\x80", 51), "=?utf-8?b?" + strings.Repeat("gICA", 16) + "?= =?utf-8?b?gICA?="},
+		{BEncoding, utf8, strings.Repeat("\x80", 48), "=?utf-8?b?" + strings.Repeat("gICA", 15) + "?= =?utf-8?b?gICA?="},
 	}
 
 	for _, test := range tests {
@@ -44,6 +42,37 @@ func TestEncodeWord(t *testing.T) {
 	}
 }
 
+func TestEncodedWordLength(t *testing.T) {
+	tests := []struct {
+		enc WordEncoder
+		src string
+	}{
+		{QEncoding, strings.Repeat("à", 30)},
+		{QEncoding, strings.Repeat("é", 60)},
+		{BEncoding, strings.Repeat("ï", 25)},
+		{BEncoding, strings.Repeat("ô", 37)},
+		{BEncoding, strings.Repeat("\x80", 50)},
+		{QEncoding, "{$firstname} Bienvendio a Apostolica, aquà inicia el camino de tu"},
+	}
+
+	for _, test := range tests {
+		s := test.enc.Encode("utf-8", test.src)
+		wordLen := 0
+		for i := 0; i < len(s); i++ {
+			if s[i] == ' ' {
+				wordLen = 0
+				continue
+			}
+
+			wordLen++
+			if wordLen > maxEncodedWordLen {
+				t.Errorf("Encode(%q) has more than %d characters: %q",
+					test.src, maxEncodedWordLen, s)
+			}
+		}
+	}
+}
+
 func TestDecodeWord(t *testing.T) {
 	tests := []struct {
 		src, exp string
@@ -203,6 +232,6 @@ func BenchmarkQDecodeHeader(b *testing.B) {
 	dec := new(WordDecoder)
 
 	for i := 0; i < b.N; i++ {
-		dec.Decode("=?utf-8?q?=C2=A1Hola,_se=C3=B1or!?=")
+		dec.DecodeHeader("=?utf-8?q?=C2=A1Hola,_se=C3=B1or!?=")
 	}
 }
diff --git a/libgo/go/mime/grammar.go b/libgo/go/mime/grammar.go
index 31b66e8f03a..6a6f71dbd40 100644
--- a/libgo/go/mime/grammar.go
+++ b/libgo/go/mime/grammar.go
@@ -11,7 +11,7 @@ import (
 // isTSpecial reports whether rune is in 'tspecials' as defined by RFC
 // 1521 and RFC 2045.
 func isTSpecial(r rune) bool {
-	return strings.IndexRune(`()<>@,;:\"/[]?=`, r) != -1
+	return strings.ContainsRune(`()<>@,;:\"/[]?=`, r)
 }
 
 // isTokenChar reports whether rune is in 'token' as defined by RFC
diff --git a/libgo/go/mime/mediatype.go b/libgo/go/mime/mediatype.go
index efee65bb00b..18454011273 100644
--- a/libgo/go/mime/mediatype.go
+++ b/libgo/go/mime/mediatype.go
@@ -221,7 +221,7 @@ func isNotTokenChar(r rune) bool {
 
 // consumeToken consumes a token from the beginning of provided
 // string, per RFC 2045 section 5.1 (referenced from 2183), and return
-// the token consumed and the rest of the string.  Returns ("", v) on
+// the token consumed and the rest of the string. Returns ("", v) on
 // failure to consume at least one character.
 func consumeToken(v string) (token, rest string) {
 	notPos := strings.IndexFunc(v, isNotTokenChar)
@@ -237,7 +237,7 @@ func consumeToken(v string) (token, rest string) {
 // consumeValue consumes a "value" per RFC 2045, where a value is
 // either a 'token' or a 'quoted-string'.  On success, consumeValue
 // returns the value consumed (and de-quoted/escaped, if a
-// quoted-string) and the rest of the string.  On failure, returns
+// quoted-string) and the rest of the string. On failure, returns
 // ("", v).
 func consumeValue(v string) (value, rest string) {
 	if v == "" {
diff --git a/libgo/go/mime/multipart/formdata.go b/libgo/go/mime/multipart/formdata.go
index eee53fc8dd0..8085bd3975b 100644
--- a/libgo/go/mime/multipart/formdata.go
+++ b/libgo/go/mime/multipart/formdata.go
@@ -20,7 +20,11 @@ import (
 // a Content-Disposition of "form-data".
 // It stores up to maxMemory bytes of the file parts in memory
 // and the remainder on disk in temporary files.
-func (r *Reader) ReadForm(maxMemory int64) (f *Form, err error) {
+func (r *Reader) ReadForm(maxMemory int64) (*Form, error) {
+	return r.readForm(maxMemory)
+}
+
+func (r *Reader) readForm(maxMemory int64) (_ *Form, err error) {
 	form := &Form{make(map[string][]string), make(map[string][]*FileHeader)}
 	defer func() {
 		if err != nil {
diff --git a/libgo/go/mime/multipart/formdata_test.go b/libgo/go/mime/multipart/formdata_test.go
index 6e2388bafef..1deca0b94df 100644
--- a/libgo/go/mime/multipart/formdata_test.go
+++ b/libgo/go/mime/multipart/formdata_test.go
@@ -88,3 +88,39 @@ Content-Disposition: form-data; name="textb"
 ` + textbValue + `
 --MyBoundary--
 `
+
+func TestReadForm_NoReadAfterEOF(t *testing.T) {
+	maxMemory := int64(32) << 20
+	boundary := `---------------------------8d345eef0d38dc9`
+	body := `
+-----------------------------8d345eef0d38dc9
+Content-Disposition: form-data; name="version"
+
+171
+-----------------------------8d345eef0d38dc9--`
+
+	mr := NewReader(&failOnReadAfterErrorReader{t: t, r: strings.NewReader(body)}, boundary)
+
+	f, err := mr.ReadForm(maxMemory)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("Got: %#v", f)
+}
+
+// failOnReadAfterErrorReader is an io.Reader wrapping r.
+// It fails t if any Read is called after a failing Read.
+type failOnReadAfterErrorReader struct {
+	t      *testing.T
+	r      io.Reader
+	sawErr error
+}
+
+func (r *failOnReadAfterErrorReader) Read(p []byte) (n int, err error) {
+	if r.sawErr != nil {
+		r.t.Fatalf("unexpected Read on Reader after previous read saw error %v", r.sawErr)
+	}
+	n, err = r.r.Read(p)
+	r.sawErr = err
+	return
+}
diff --git a/libgo/go/mime/multipart/multipart.go b/libgo/go/mime/multipart/multipart.go
index 3b746a5e157..205348ca89d 100644
--- a/libgo/go/mime/multipart/multipart.go
+++ b/libgo/go/mime/multipart/multipart.go
@@ -96,7 +96,7 @@ func (p *Part) parseContentDisposition() {
 func NewReader(r io.Reader, boundary string) *Reader {
 	b := []byte("\r\n--" + boundary + "--")
 	return &Reader{
-		bufReader:        bufio.NewReaderSize(r, peekBufferSize),
+		bufReader:        bufio.NewReaderSize(&stickyErrorReader{r: r}, peekBufferSize),
 		nl:               b[:2],
 		nlDashBoundary:   b[:len(b)-2],
 		dashBoundaryDash: b[2:],
@@ -104,6 +104,24 @@ func NewReader(r io.Reader, boundary string) *Reader {
 	}
 }
 
+// stickyErrorReader is an io.Reader which never calls Read on its
+// underlying Reader once an error has been seen. (the io.Reader
+// interface's contract promises nothing about the return values of
+// Read calls after an error, yet this package does do multiple Reads
+// after error)
+type stickyErrorReader struct {
+	r   io.Reader
+	err error
+}
+
+func (r *stickyErrorReader) Read(p []byte) (n int, _ error) {
+	if r.err != nil {
+		return 0, r.err
+	}
+	n, r.err = r.r.Read(p)
+	return n, r.err
+}
+
 func newPart(mr *Reader) (*Part, error) {
 	bp := &Part{
 		Header: make(map[string][]string),
@@ -150,13 +168,13 @@ func (pr partReader) Read(d []byte) (n int, err error) {
 	}()
 	if p.buffer.Len() >= len(d) {
 		// Internal buffer of unconsumed data is large enough for
-		// the read request.  No need to parse more at the moment.
+		// the read request. No need to parse more at the moment.
 		return p.buffer.Read(d)
 	}
 	peek, err := p.mr.bufReader.Peek(peekBufferSize) // TODO(bradfitz): add buffer size accessor
 
 	// Look for an immediate empty part without a leading \r\n
-	// before the boundary separator.  Some MIME code makes empty
+	// before the boundary separator. Some MIME code makes empty
 	// parts like this. Most browsers, however, write the \r\n
 	// before the subsequent boundary even for empty parts and
 	// won't hit this path.
@@ -210,7 +228,7 @@ func (p *Part) Close() error {
 }
 
 // Reader is an iterator over parts in a MIME multipart body.
-// Reader's underlying parser consumes its input as needed.  Seeking
+// Reader's underlying parser consumes its input as needed. Seeking
 // isn't supported.
 type Reader struct {
 	bufReader *bufio.Reader
@@ -310,7 +328,7 @@ func (mr *Reader) isBoundaryDelimiterLine(line []byte) (ret bool) {
 	rest = skipLWSPChar(rest)
 
 	// On the first part, see our lines are ending in \n instead of \r\n
-	// and switch into that mode if so.  This is a violation of the spec,
+	// and switch into that mode if so. This is a violation of the spec,
 	// but occurs in practice.
 	if mr.partsRead == 0 && len(rest) == 1 && rest[0] == '\n' {
 		mr.nl = mr.nl[1:]
diff --git a/libgo/go/mime/multipart/multipart_test.go b/libgo/go/mime/multipart/multipart_test.go
index d06bb4159aa..82a7f86e67c 100644
--- a/libgo/go/mime/multipart/multipart_test.go
+++ b/libgo/go/mime/multipart/multipart_test.go
@@ -446,8 +446,8 @@ type parseTest struct {
 var parseTests = []parseTest{
 	// Actual body from App Engine on a blob upload. The final part (the
 	// Content-Type: message/external-body) is what App Engine replaces
-	// the uploaded file with.  The other form fields (prefixed with
-	// "other" in their form-data name) are unchanged.  A bug was
+	// the uploaded file with. The other form fields (prefixed with
+	// "other" in their form-data name) are unchanged. A bug was
 	// reported with blob uploads failing when the other fields were
 	// empty. This was the MIME POST body that previously failed.
 	{
diff --git a/libgo/go/mime/multipart/writer.go b/libgo/go/mime/multipart/writer.go
index 80960939d62..f82756d5518 100644
--- a/libgo/go/mime/multipart/writer.go
+++ b/libgo/go/mime/multipart/writer.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"io"
 	"net/textproto"
+	"sort"
 	"strings"
 )
 
@@ -94,10 +95,14 @@ func (w *Writer) CreatePart(header textproto.MIMEHeader) (io.Writer, error) {
 	} else {
 		fmt.Fprintf(&b, "--%s\r\n", w.boundary)
 	}
-	// TODO(bradfitz): move this to textproto.MimeHeader.Write(w), have it sort
-	// and clean, like http.Header.Write(w) does.
-	for k, vv := range header {
-		for _, v := range vv {
+
+	keys := make([]string, 0, len(header))
+	for k := range header {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	for _, k := range keys {
+		for _, v := range header[k] {
 			fmt.Fprintf(&b, "%s: %s\r\n", k, v)
 		}
 	}
diff --git a/libgo/go/mime/multipart/writer_test.go b/libgo/go/mime/multipart/writer_test.go
index ba00c97ecee..9670c660a4a 100644
--- a/libgo/go/mime/multipart/writer_test.go
+++ b/libgo/go/mime/multipart/writer_test.go
@@ -7,6 +7,7 @@ package multipart
 import (
 	"bytes"
 	"io/ioutil"
+	"net/textproto"
 	"strings"
 	"testing"
 )
@@ -126,3 +127,32 @@ func TestWriterBoundaryGoroutines(t *testing.T) {
 	w.Boundary()
 	<-done
 }
+
+func TestSortedHeader(t *testing.T) {
+	var buf bytes.Buffer
+	w := NewWriter(&buf)
+	if err := w.SetBoundary("MIMEBOUNDARY"); err != nil {
+		t.Fatalf("Error setting mime boundary: %v", err)
+	}
+
+	header := textproto.MIMEHeader{
+		"A": {"2"},
+		"B": {"5", "7", "6"},
+		"C": {"4"},
+		"M": {"3"},
+		"Z": {"1"},
+	}
+
+	part, err := w.CreatePart(header)
+	if err != nil {
+		t.Fatalf("Unable to create part: %v", err)
+	}
+	part.Write([]byte("foo"))
+
+	w.Close()
+
+	want := "--MIMEBOUNDARY\r\nA: 2\r\nB: 5\r\nB: 7\r\nB: 6\r\nC: 4\r\nM: 3\r\nZ: 1\r\n\r\nfoo\r\n--MIMEBOUNDARY--\r\n"
+	if want != buf.String() {
+		t.Fatalf("\n got: %q\nwant: %q\n", buf.String(), want)
+	}
+}
diff --git a/libgo/go/mime/type_plan9.go b/libgo/go/mime/type_plan9.go
index c3ba186e7c6..14ff9734051 100644
--- a/libgo/go/mime/type_plan9.go
+++ b/libgo/go/mime/type_plan9.go
@@ -21,7 +21,7 @@ func initMimePlan9() {
 }
 
 var typeFiles = []string{
-	"/sys/lib/mimetypes",
+	"/sys/lib/mimetype",
 }
 
 func initMimeForTests() map[string]string {
diff --git a/libgo/go/net/addrselect.go b/libgo/go/net/addrselect.go
index 58ab7d706c6..0b9d160fd43 100644
--- a/libgo/go/net/addrselect.go
+++ b/libgo/go/net/addrselect.go
@@ -203,7 +203,7 @@ func (s *byRFC6724) Less(i, j int) bool {
 		// (e.g., https://golang.org/issue/13283).  Glibc instead only
 		// uses CommonPrefixLen for IPv4 when the source and destination
 		// addresses are on the same subnet, but that requires extra
-		// work to find the netmask for our source addresses.  As a
+		// work to find the netmask for our source addresses. As a
 		// simpler heuristic, we limit its use to when the source and
 		// destination belong to the same special purpose block.
 		if da4 {
diff --git a/libgo/go/net/cgo_android.go b/libgo/go/net/cgo_android.go
index fe9925b840a..ab0368d14b5 100644
--- a/libgo/go/net/cgo_android.go
+++ b/libgo/go/net/cgo_android.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/cgo_bsd.go b/libgo/go/net/cgo_bsd.go
index ae1054b39ad..c1adf20cd90 100644
--- a/libgo/go/net/cgo_bsd.go
+++ b/libgo/go/net/cgo_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/cgo_linux.go b/libgo/go/net/cgo_linux.go
index baf207257fa..36bac3439f8 100644
--- a/libgo/go/net/cgo_linux.go
+++ b/libgo/go/net/cgo_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/cgo_netbsd.go b/libgo/go/net/cgo_netbsd.go
index 8a16871906d..1ce0139237b 100644
--- a/libgo/go/net/cgo_netbsd.go
+++ b/libgo/go/net/cgo_netbsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/cgo_openbsd.go b/libgo/go/net/cgo_openbsd.go
index 183091366cb..4610246561e 100644
--- a/libgo/go/net/cgo_openbsd.go
+++ b/libgo/go/net/cgo_openbsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/cgo_solaris.go b/libgo/go/net/cgo_solaris.go
index 05811c6c252..bd1e8f3ae84 100644
--- a/libgo/go/net/cgo_solaris.go
+++ b/libgo/go/net/cgo_solaris.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/cgo_stub.go b/libgo/go/net/cgo_stub.go
index b86ff7daf19..51259722aec 100644
--- a/libgo/go/net/cgo_stub.go
+++ b/libgo/go/net/cgo_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,6 +6,8 @@
 
 package net
 
+import "context"
+
 func init() { netGo = true }
 
 type addrinfoErrno int
@@ -14,22 +16,22 @@ func (eai addrinfoErrno) Error() string   { return "<nil>" }
 func (eai addrinfoErrno) Temporary() bool { return false }
 func (eai addrinfoErrno) Timeout() bool   { return false }
 
-func cgoLookupHost(name string) (addrs []string, err error, completed bool) {
+func cgoLookupHost(ctx context.Context, name string) (addrs []string, err error, completed bool) {
 	return nil, nil, false
 }
 
-func cgoLookupPort(network, service string) (port int, err error, completed bool) {
+func cgoLookupPort(ctx context.Context, network, service string) (port int, err error, completed bool) {
 	return 0, nil, false
 }
 
-func cgoLookupIP(name string) (addrs []IPAddr, err error, completed bool) {
+func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, completed bool) {
 	return nil, nil, false
 }
 
-func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
+func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error, completed bool) {
 	return "", nil, false
 }
 
-func cgoLookupPTR(addr string) (ptrs []string, err error, completed bool) {
+func cgoLookupPTR(ctx context.Context, addr string) (ptrs []string, err error, completed bool) {
 	return nil, nil, false
 }
diff --git a/libgo/go/net/cgo_unix.go b/libgo/go/net/cgo_unix.go
index f634323ed8b..525c63c18d2 100644
--- a/libgo/go/net/cgo_unix.go
+++ b/libgo/go/net/cgo_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -18,6 +18,7 @@ package net
 */
 
 import (
+	"context"
 	"syscall"
 	"unsafe"
 )
@@ -51,18 +52,31 @@ func (eai addrinfoErrno) Error() string   { return bytePtrToString(libc_gai_stre
 func (eai addrinfoErrno) Temporary() bool { return eai == syscall.EAI_AGAIN }
 func (eai addrinfoErrno) Timeout() bool   { return false }
 
-func cgoLookupHost(name string) (hosts []string, err error, completed bool) {
-	addrs, err, completed := cgoLookupIP(name)
+type portLookupResult struct {
+	port int
+	err  error
+}
+
+type ipLookupResult struct {
+	addrs []IPAddr
+	cname string
+	err   error
+}
+
+type reverseLookupResult struct {
+	names []string
+	err   error
+}
+
+func cgoLookupHost(ctx context.Context, name string) (hosts []string, err error, completed bool) {
+	addrs, err, completed := cgoLookupIP(ctx, name)
 	for _, addr := range addrs {
 		hosts = append(hosts, addr.String())
 	}
 	return
 }
 
-func cgoLookupPort(network, service string) (port int, err error, completed bool) {
-	acquireThread()
-	defer releaseThread()
-
+func cgoLookupPort(ctx context.Context, network, service string) (port int, err error, completed bool) {
 	var hints syscall.Addrinfo
 	switch network {
 	case "": // no hints
@@ -83,11 +97,27 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
 			hints.Ai_family = syscall.AF_INET6
 		}
 	}
+	if ctx.Done() == nil {
+		port, err := cgoLookupServicePort(&hints, network, service)
+		return port, err, true
+	}
+	result := make(chan portLookupResult, 1)
+	go cgoPortLookup(result, &hints, network, service)
+	select {
+	case r := <-result:
+		return r.port, r.err, true
+	case <-ctx.Done():
+		// Since there isn't a portable way to cancel the lookup,
+		// we just let it finish and write to the buffered channel.
+		return 0, mapErr(ctx.Err()), false
+	}
+}
 
+func cgoLookupServicePort(hints *syscall.Addrinfo, network, service string) (port int, err error) {
 	s := syscall.StringBytePtr(service)
 	var res *syscall.Addrinfo
 	syscall.Entersyscall()
-	gerrno := libc_getaddrinfo(nil, s, &hints, &res)
+	gerrno := libc_getaddrinfo(nil, s, hints, &res)
 	syscall.Exitsyscall()
 	if gerrno != 0 {
 		switch gerrno {
@@ -100,7 +130,7 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
 		default:
 			err = addrinfoErrno(gerrno)
 		}
-		return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}, true
+		return 0, &DNSError{Err: err.Error(), Name: network + "/" + service}
 	}
 	defer libc_freeaddrinfo(res)
 
@@ -109,17 +139,22 @@ func cgoLookupPort(network, service string) (port int, err error, completed bool
 		case syscall.AF_INET:
 			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
 			p := (*[2]byte)(unsafe.Pointer(&sa.Port))
-			return int(p[0])<<8 | int(p[1]), nil, true
+			return int(p[0])<<8 | int(p[1]), nil
 		case syscall.AF_INET6:
 			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
 			p := (*[2]byte)(unsafe.Pointer(&sa.Port))
-			return int(p[0])<<8 | int(p[1]), nil, true
+			return int(p[0])<<8 | int(p[1]), nil
 		}
 	}
-	return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}, true
+	return 0, &DNSError{Err: "unknown port", Name: network + "/" + service}
 }
 
-func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, completed bool) {
+func cgoPortLookup(result chan<- portLookupResult, hints *syscall.Addrinfo, network, service string) {
+	port, err := cgoLookupServicePort(hints, network, service)
+	result <- portLookupResult{port, err}
+}
+
+func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error) {
 	acquireThread()
 	defer releaseThread()
 
@@ -152,7 +187,7 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, com
 		default:
 			err = addrinfoErrno(gerrno)
 		}
-		return nil, "", &DNSError{Err: err.Error(), Name: name}, true
+		return nil, "", &DNSError{Err: err.Error(), Name: name}
 	}
 	defer libc_freeaddrinfo(res)
 
@@ -181,17 +216,42 @@ func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, com
 			addrs = append(addrs, addr)
 		}
 	}
-	return addrs, cname, nil, true
+	return addrs, cname, nil
 }
 
-func cgoLookupIP(name string) (addrs []IPAddr, err error, completed bool) {
-	addrs, _, err, completed = cgoLookupIPCNAME(name)
-	return
+func cgoIPLookup(result chan<- ipLookupResult, name string) {
+	addrs, cname, err := cgoLookupIPCNAME(name)
+	result <- ipLookupResult{addrs, cname, err}
 }
 
-func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
-	_, cname, err, completed = cgoLookupIPCNAME(name)
-	return
+func cgoLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error, completed bool) {
+	if ctx.Done() == nil {
+		addrs, _, err = cgoLookupIPCNAME(name)
+		return addrs, err, true
+	}
+	result := make(chan ipLookupResult, 1)
+	go cgoIPLookup(result, name)
+	select {
+	case r := <-result:
+		return r.addrs, r.err, true
+	case <-ctx.Done():
+		return nil, mapErr(ctx.Err()), false
+	}
+}
+
+func cgoLookupCNAME(ctx context.Context, name string) (cname string, err error, completed bool) {
+	if ctx.Done() == nil {
+		_, cname, err = cgoLookupIPCNAME(name)
+		return cname, err, true
+	}
+	result := make(chan ipLookupResult, 1)
+	go cgoIPLookup(result, name)
+	select {
+	case r := <-result:
+		return r.cname, r.err, true
+	case <-ctx.Done():
+		return "", mapErr(ctx.Err()), false
+	}
 }
 
 // These are roughly enough for the following:
@@ -207,10 +267,7 @@ const (
 	maxNameinfoLen = 4096
 )
 
-func cgoLookupPTR(addr string) ([]string, error, bool) {
-	acquireThread()
-	defer releaseThread()
-
+func cgoLookupPTR(ctx context.Context, addr string) (names []string, err error, completed bool) {
 	var zone string
 	ip := parseIPv4(addr)
 	if ip == nil {
@@ -223,9 +280,26 @@ func cgoLookupPTR(addr string) ([]string, error, bool) {
 	if sa == nil {
 		return nil, &DNSError{Err: "invalid address " + ip.String(), Name: addr}, true
 	}
-	var err error
-	var b []byte
+	if ctx.Done() == nil {
+		names, err := cgoLookupAddrPTR(addr, sa, salen)
+		return names, err, true
+	}
+	result := make(chan reverseLookupResult, 1)
+	go cgoReverseLookup(result, addr, sa, salen)
+	select {
+	case r := <-result:
+		return r.names, r.err, true
+	case <-ctx.Done():
+		return nil, mapErr(ctx.Err()), false
+	}
+}
+
+func cgoLookupAddrPTR(addr string, sa *syscall.RawSockaddr, salen syscall.Socklen_t) (names []string, err error) {
+	acquireThread()
+	defer releaseThread()
+
 	var gerrno int
+	var b []byte
 	for l := nameinfoLen; l <= maxNameinfoLen; l *= 2 {
 		b = make([]byte, l)
 		gerrno, err = cgoNameinfoPTR(b, sa, salen)
@@ -242,16 +316,20 @@ func cgoLookupPTR(addr string) ([]string, error, bool) {
 		default:
 			err = addrinfoErrno(gerrno)
 		}
-		return nil, &DNSError{Err: err.Error(), Name: addr}, true
+		return nil, &DNSError{Err: err.Error(), Name: addr}
 	}
-
 	for i := 0; i < len(b); i++ {
 		if b[i] == 0 {
 			b = b[:i]
 			break
 		}
 	}
-	return []string{absDomainName(b)}, nil, true
+	return []string{absDomainName(b)}, nil
+}
+
+func cgoReverseLookup(result chan<- reverseLookupResult, addr string, sa *syscall.RawSockaddr, salen syscall.Socklen_t) {
+	names, err := cgoLookupAddrPTR(addr, sa, salen)
+	result <- reverseLookupResult{names, err}
 }
 
 func cgoSockaddr(ip IP, zone string) (*syscall.RawSockaddr, syscall.Socklen_t) {
diff --git a/libgo/go/net/cgo_unix_test.go b/libgo/go/net/cgo_unix_test.go
index 4d5ab23fd36..e861c7aa1f9 100644
--- a/libgo/go/net/cgo_unix_test.go
+++ b/libgo/go/net/cgo_unix_test.go
@@ -7,18 +7,76 @@
 
 package net
 
-import "testing"
+import (
+	"context"
+	"testing"
+)
 
 func TestCgoLookupIP(t *testing.T) {
-	host := "localhost"
-	_, err, ok := cgoLookupIP(host)
+	ctx := context.Background()
+	_, err, ok := cgoLookupIP(ctx, "localhost")
 	if !ok {
 		t.Errorf("cgoLookupIP must not be a placeholder")
 	}
 	if err != nil {
 		t.Error(err)
 	}
-	if _, err := goLookupIP(host); err != nil {
+}
+
+func TestCgoLookupIPWithCancel(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	_, err, ok := cgoLookupIP(ctx, "localhost")
+	if !ok {
+		t.Errorf("cgoLookupIP must not be a placeholder")
+	}
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestCgoLookupPort(t *testing.T) {
+	ctx := context.Background()
+	_, err, ok := cgoLookupPort(ctx, "tcp", "smtp")
+	if !ok {
+		t.Errorf("cgoLookupPort must not be a placeholder")
+	}
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestCgoLookupPortWithCancel(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	_, err, ok := cgoLookupPort(ctx, "tcp", "smtp")
+	if !ok {
+		t.Errorf("cgoLookupPort must not be a placeholder")
+	}
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestCgoLookupPTR(t *testing.T) {
+	ctx := context.Background()
+	_, err, ok := cgoLookupPTR(ctx, "127.0.0.1")
+	if !ok {
+		t.Errorf("cgoLookupPTR must not be a placeholder")
+	}
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func TestCgoLookupPTRWithCancel(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	_, err, ok := cgoLookupPTR(ctx, "127.0.0.1")
+	if !ok {
+		t.Errorf("cgoLookupPTR must not be a placeholder")
+	}
+	if err != nil {
 		t.Error(err)
 	}
 }
diff --git a/libgo/go/net/conf.go b/libgo/go/net/conf.go
index ddaa978f4f6..eb729167f5b 100644
--- a/libgo/go/net/conf.go
+++ b/libgo/go/net/conf.go
@@ -124,16 +124,17 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 			print("go package net: hostLookupOrder(", hostname, ") = ", ret.String(), "\n")
 		}()
 	}
+	fallbackOrder := hostLookupCgo
 	if c.netGo {
-		return hostLookupFilesDNS
+		fallbackOrder = hostLookupFilesDNS
 	}
 	if c.forceCgoLookupHost || c.resolv.unknownOpt || c.goos == "android" {
-		return hostLookupCgo
+		return fallbackOrder
 	}
 	if byteIndex(hostname, '\\') != -1 || byteIndex(hostname, '%') != -1 {
 		// Don't deal with special form hostnames with backslashes
 		// or '%'.
-		return hostLookupCgo
+		return fallbackOrder
 	}
 
 	// OpenBSD is unique and doesn't use nsswitch.conf.
@@ -154,7 +155,7 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 			return hostLookupDNSFiles
 		}
 		if len(lookup) < 1 || len(lookup) > 2 {
-			return hostLookupCgo
+			return fallbackOrder
 		}
 		switch lookup[0] {
 		case "bind":
@@ -162,7 +163,7 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 				if lookup[1] == "file" {
 					return hostLookupDNSFiles
 				}
-				return hostLookupCgo
+				return fallbackOrder
 			}
 			return hostLookupDNS
 		case "file":
@@ -170,11 +171,11 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 				if lookup[1] == "bind" {
 					return hostLookupFilesDNS
 				}
-				return hostLookupCgo
+				return fallbackOrder
 			}
 			return hostLookupFiles
 		default:
-			return hostLookupCgo
+			return fallbackOrder
 		}
 	}
 
@@ -185,11 +186,11 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 		hostname = hostname[:len(hostname)-1]
 	}
 	if stringsHasSuffixFold(hostname, ".local") {
-		// Per RFC 6762, the ".local" TLD is special.  And
+		// Per RFC 6762, the ".local" TLD is special. And
 		// because Go's native resolver doesn't do mDNS or
 		// similar local resolution mechanisms, assume that
 		// libc might (via Avahi, etc) and use cgo.
-		return hostLookupCgo
+		return fallbackOrder
 	}
 
 	nss := c.nss
@@ -199,7 +200,7 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 	if os.IsNotExist(nss.err) || (nss.err == nil && len(srcs) == 0) {
 		if c.goos == "solaris" {
 			// illumos defaults to "nis [NOTFOUND=return] files"
-			return hostLookupCgo
+			return fallbackOrder
 		}
 		if c.goos == "linux" {
 			// glibc says the default is "dns [!UNAVAIL=return] files"
@@ -212,21 +213,21 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 		// We failed to parse or open nsswitch.conf, so
 		// conservatively assume we should use cgo if it's
 		// available.
-		return hostLookupCgo
+		return fallbackOrder
 	}
 
 	var mdnsSource, filesSource, dnsSource bool
 	var first string
 	for _, src := range srcs {
 		if src.source == "myhostname" {
-			if hasDot {
+			if hostname == "" || hasDot {
 				continue
 			}
-			return hostLookupCgo
+			return fallbackOrder
 		}
 		if src.source == "files" || src.source == "dns" {
 			if !src.standardCriteria() {
-				return hostLookupCgo // non-standard; let libc deal with it.
+				return fallbackOrder // non-standard; let libc deal with it.
 			}
 			if src.source == "files" {
 				filesSource = true
@@ -246,14 +247,14 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 			continue
 		}
 		// Some source we don't know how to deal with.
-		return hostLookupCgo
+		return fallbackOrder
 	}
 
 	// We don't parse mdns.allow files. They're rare. If one
 	// exists, it might list other TLDs (besides .local) or even
 	// '*', so just let libc deal with it.
 	if mdnsSource && c.hasMDNSAllow {
-		return hostLookupCgo
+		return fallbackOrder
 	}
 
 	// Cases where Go can handle it without cgo and C thread
@@ -272,7 +273,7 @@ func (c *conf) hostLookupOrder(hostname string) (ret hostLookupOrder) {
 	}
 
 	// Something weird. Let libc deal with it.
-	return hostLookupCgo
+	return fallbackOrder
 }
 
 // goDebugNetDNS parses the value of the GODEBUG "netdns" value.
diff --git a/libgo/go/net/conf_netcgo.go b/libgo/go/net/conf_netcgo.go
index b66bae37106..abc33cee475 100644
--- a/libgo/go/net/conf_netcgo.go
+++ b/libgo/go/net/conf_netcgo.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/conf_test.go b/libgo/go/net/conf_test.go
index 86904bffde7..ec8814b845b 100644
--- a/libgo/go/net/conf_test.go
+++ b/libgo/go/net/conf_test.go
@@ -32,7 +32,6 @@ func TestConfHostLookupOrder(t *testing.T) {
 	tests := []struct {
 		name      string
 		c         *conf
-		goos      string
 		hostTests []nssHostTest
 	}{
 		{
@@ -48,6 +47,28 @@ func TestConfHostLookupOrder(t *testing.T) {
 			},
 		},
 		{
+			name: "netgo_dns_before_files",
+			c: &conf{
+				netGo:  true,
+				nss:    nssStr("hosts: dns files"),
+				resolv: defaultResolvConf,
+			},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupDNSFiles},
+			},
+		},
+		{
+			name: "netgo_fallback_on_cgo",
+			c: &conf{
+				netGo:  true,
+				nss:    nssStr("hosts: dns files something_custom"),
+				resolv: defaultResolvConf,
+			},
+			hostTests: []nssHostTest{
+				{"x.com", hostLookupFilesDNS},
+			},
+		},
+		{
 			name: "ubuntu_trusty_avahi",
 			c: &conf{
 				nss:    nssStr("hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4"),
@@ -236,6 +257,7 @@ func TestConfHostLookupOrder(t *testing.T) {
 			hostTests: []nssHostTest{
 				{"x.com", hostLookupFilesDNS},
 				{"somehostname", hostLookupCgo},
+				{"", hostLookupFilesDNS}, // Issue 13623
 			},
 		},
 		{
diff --git a/libgo/go/net/conn_test.go b/libgo/go/net/conn_test.go
index 6995c110f20..16cf69ee169 100644
--- a/libgo/go/net/conn_test.go
+++ b/libgo/go/net/conn_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -43,7 +43,7 @@ func TestConnAndListener(t *testing.T) {
 			t.Fatal(err)
 		}
 		defer c.Close()
-		if c.LocalAddr().Network() != network || c.LocalAddr().Network() != network {
+		if c.LocalAddr().Network() != network || c.RemoteAddr().Network() != network {
 			t.Fatalf("got %s->%s; want %s->%s", c.LocalAddr().Network(), c.RemoteAddr().Network(), network, network)
 		}
 		c.SetDeadline(time.Now().Add(someTimeout))
diff --git a/libgo/go/net/dial.go b/libgo/go/net/dial.go
index 193776fe413..55edb433953 100644
--- a/libgo/go/net/dial.go
+++ b/libgo/go/net/dial.go
@@ -1,11 +1,12 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
-	"errors"
+	"context"
+	"internal/nettrace"
 	"time"
 )
 
@@ -61,21 +62,34 @@ type Dialer struct {
 	// Cancel is an optional channel whose closure indicates that
 	// the dial should be canceled. Not all types of dials support
 	// cancelation.
+	//
+	// Deprecated: Use DialContext instead.
 	Cancel <-chan struct{}
 }
 
-// Return either now+Timeout or Deadline, whichever comes first.
-// Or zero, if neither is set.
-func (d *Dialer) deadline(now time.Time) time.Time {
-	if d.Timeout == 0 {
-		return d.Deadline
+func minNonzeroTime(a, b time.Time) time.Time {
+	if a.IsZero() {
+		return b
 	}
-	timeoutDeadline := now.Add(d.Timeout)
-	if d.Deadline.IsZero() || timeoutDeadline.Before(d.Deadline) {
-		return timeoutDeadline
-	} else {
-		return d.Deadline
+	if b.IsZero() || a.Before(b) {
+		return a
+	}
+	return b
+}
+
+// deadline returns the earliest of:
+//   - now+Timeout
+//   - d.Deadline
+//   - the context's deadline
+// Or zero, if none of Timeout, Deadline, or context's deadline is set.
+func (d *Dialer) deadline(ctx context.Context, now time.Time) (earliest time.Time) {
+	if d.Timeout != 0 { // including negative, for historical reasons
+		earliest = now.Add(d.Timeout)
+	}
+	if d, ok := ctx.Deadline(); ok {
+		earliest = minNonzeroTime(earliest, d)
 	}
+	return minNonzeroTime(earliest, d.Deadline)
 }
 
 // partialDeadline returns the deadline to use for a single address,
@@ -110,7 +124,7 @@ func (d *Dialer) fallbackDelay() time.Duration {
 	}
 }
 
-func parseNetwork(net string) (afnet string, proto int, err error) {
+func parseNetwork(ctx context.Context, net string) (afnet string, proto int, err error) {
 	i := last(net, ':')
 	if i < 0 { // no colon
 		switch net {
@@ -129,7 +143,7 @@ func parseNetwork(net string) (afnet string, proto int, err error) {
 		protostr := net[i+1:]
 		proto, i, ok := dtoi(protostr, 0)
 		if !ok || i != len(protostr) {
-			proto, err = lookupProtocol(protostr)
+			proto, err = lookupProtocol(ctx, protostr)
 			if err != nil {
 				return "", 0, err
 			}
@@ -139,8 +153,11 @@ func parseNetwork(net string) (afnet string, proto int, err error) {
 	return "", 0, UnknownNetworkError(net)
 }
 
-func resolveAddrList(op, net, addr string, deadline time.Time) (addrList, error) {
-	afnet, _, err := parseNetwork(net)
+// resolverAddrList resolves addr using hint and returns a list of
+// addresses. The result contains at least one address when error is
+// nil.
+func resolveAddrList(ctx context.Context, op, network, addr string, hint Addr) (addrList, error) {
+	afnet, _, err := parseNetwork(ctx, network)
 	if err != nil {
 		return nil, err
 	}
@@ -149,13 +166,64 @@ func resolveAddrList(op, net, addr string, deadline time.Time) (addrList, error)
 	}
 	switch afnet {
 	case "unix", "unixgram", "unixpacket":
+		// TODO(bradfitz): push down context
 		addr, err := ResolveUnixAddr(afnet, addr)
 		if err != nil {
 			return nil, err
 		}
+		if op == "dial" && hint != nil && addr.Network() != hint.Network() {
+			return nil, &AddrError{Err: "mismatched local address type", Addr: hint.String()}
+		}
 		return addrList{addr}, nil
 	}
-	return internetAddrList(afnet, addr, deadline)
+	addrs, err := internetAddrList(ctx, afnet, addr)
+	if err != nil || op != "dial" || hint == nil {
+		return addrs, err
+	}
+	var (
+		tcp      *TCPAddr
+		udp      *UDPAddr
+		ip       *IPAddr
+		wildcard bool
+	)
+	switch hint := hint.(type) {
+	case *TCPAddr:
+		tcp = hint
+		wildcard = tcp.isWildcard()
+	case *UDPAddr:
+		udp = hint
+		wildcard = udp.isWildcard()
+	case *IPAddr:
+		ip = hint
+		wildcard = ip.isWildcard()
+	}
+	naddrs := addrs[:0]
+	for _, addr := range addrs {
+		if addr.Network() != hint.Network() {
+			return nil, &AddrError{Err: "mismatched local address type", Addr: hint.String()}
+		}
+		switch addr := addr.(type) {
+		case *TCPAddr:
+			if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(tcp.IP) {
+				continue
+			}
+			naddrs = append(naddrs, addr)
+		case *UDPAddr:
+			if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(udp.IP) {
+				continue
+			}
+			naddrs = append(naddrs, addr)
+		case *IPAddr:
+			if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(ip.IP) {
+				continue
+			}
+			naddrs = append(naddrs, addr)
+		}
+	}
+	if len(naddrs) == 0 {
+		return nil, errNoSuitableAddress
+	}
+	return naddrs, nil
 }
 
 // Dial connects to the address on the named network.
@@ -173,8 +241,8 @@ func resolveAddrList(op, net, addr string, deadline time.Time) (addrList, error)
 // If the host is empty, as in ":80", the local system is assumed.
 //
 // Examples:
-//	Dial("tcp", "12.34.56.78:80")
-//	Dial("tcp", "google.com:http")
+//	Dial("tcp", "192.0.2.1:80")
+//	Dial("tcp", "golang.org:http")
 //	Dial("tcp", "[2001:db8::1]:http")
 //	Dial("tcp", "[fe80::1%lo0]:80")
 //	Dial("tcp", ":80")
@@ -184,8 +252,8 @@ func resolveAddrList(op, net, addr string, deadline time.Time) (addrList, error)
 // literal IP address.
 //
 // Examples:
-//	Dial("ip4:1", "127.0.0.1")
-//	Dial("ip6:ospf", "::1")
+//	Dial("ip4:1", "192.0.2.1")
+//	Dial("ip6:ipv6-icmp", "2001:db8::1")
 //
 // For Unix networks, the address must be a file system path.
 func Dial(network, address string) (Conn, error) {
@@ -200,11 +268,10 @@ func DialTimeout(network, address string, timeout time.Duration) (Conn, error) {
 	return d.Dial(network, address)
 }
 
-// dialContext holds common state for all dial operations.
-type dialContext struct {
+// dialParam contains a Dial's parameters and configuration.
+type dialParam struct {
 	Dialer
 	network, address string
-	finalDeadline    time.Time
 }
 
 // Dial connects to the address on the named network.
@@ -212,17 +279,62 @@ type dialContext struct {
 // See func Dial for a description of the network and address
 // parameters.
 func (d *Dialer) Dial(network, address string) (Conn, error) {
-	finalDeadline := d.deadline(time.Now())
-	addrs, err := resolveAddrList("dial", network, address, finalDeadline)
+	return d.DialContext(context.Background(), network, address)
+}
+
+// DialContext connects to the address on the named network using
+// the provided context.
+//
+// The provided Context must be non-nil. If the context expires before
+// the connection is complete, an error is returned. Once successfully
+// connected, any expiration of the context will not affect the
+// connection.
+//
+// See func Dial for a description of the network and address
+// parameters.
+func (d *Dialer) DialContext(ctx context.Context, network, address string) (Conn, error) {
+	if ctx == nil {
+		panic("nil context")
+	}
+	deadline := d.deadline(ctx, time.Now())
+	if !deadline.IsZero() {
+		if d, ok := ctx.Deadline(); !ok || deadline.Before(d) {
+			subCtx, cancel := context.WithDeadline(ctx, deadline)
+			defer cancel()
+			ctx = subCtx
+		}
+	}
+	if oldCancel := d.Cancel; oldCancel != nil {
+		subCtx, cancel := context.WithCancel(ctx)
+		defer cancel()
+		go func() {
+			select {
+			case <-oldCancel:
+				cancel()
+			case <-subCtx.Done():
+			}
+		}()
+		ctx = subCtx
+	}
+
+	// Shadow the nettrace (if any) during resolve so Connect events don't fire for DNS lookups.
+	resolveCtx := ctx
+	if trace, _ := ctx.Value(nettrace.TraceKey{}).(*nettrace.Trace); trace != nil {
+		shadow := *trace
+		shadow.ConnectStart = nil
+		shadow.ConnectDone = nil
+		resolveCtx = context.WithValue(resolveCtx, nettrace.TraceKey{}, &shadow)
+	}
+
+	addrs, err := resolveAddrList(resolveCtx, "dial", network, address, d.LocalAddr)
 	if err != nil {
 		return nil, &OpError{Op: "dial", Net: network, Source: nil, Addr: nil, Err: err}
 	}
 
-	ctx := &dialContext{
-		Dialer:        *d,
-		network:       network,
-		address:       address,
-		finalDeadline: finalDeadline,
+	dp := &dialParam{
+		Dialer:  *d,
+		network: network,
+		address: address,
 	}
 
 	var primaries, fallbacks addrList
@@ -233,116 +345,128 @@ func (d *Dialer) Dial(network, address string) (Conn, error) {
 	}
 
 	var c Conn
-	if len(fallbacks) == 0 {
-		// dialParallel can accept an empty fallbacks list,
-		// but this shortcut avoids the goroutine/channel overhead.
-		c, err = dialSerial(ctx, primaries, nil)
+	if len(fallbacks) > 0 {
+		c, err = dialParallel(ctx, dp, primaries, fallbacks)
 	} else {
-		c, err = dialParallel(ctx, primaries, fallbacks)
+		c, err = dialSerial(ctx, dp, primaries)
+	}
+	if err != nil {
+		return nil, err
 	}
 
-	if d.KeepAlive > 0 && err == nil {
-		if tc, ok := c.(*TCPConn); ok {
-			setKeepAlive(tc.fd, true)
-			setKeepAlivePeriod(tc.fd, d.KeepAlive)
-			testHookSetKeepAlive()
-		}
+	if tc, ok := c.(*TCPConn); ok && d.KeepAlive > 0 {
+		setKeepAlive(tc.fd, true)
+		setKeepAlivePeriod(tc.fd, d.KeepAlive)
+		testHookSetKeepAlive()
 	}
-	return c, err
+	return c, nil
 }
 
 // dialParallel races two copies of dialSerial, giving the first a
 // head start. It returns the first established connection and
 // closes the others. Otherwise it returns an error from the first
 // primary address.
-func dialParallel(ctx *dialContext, primaries, fallbacks addrList) (Conn, error) {
-	results := make(chan dialResult) // unbuffered, so dialSerialAsync can detect race loss & cleanup
-	cancel := make(chan struct{})
-	defer close(cancel)
-
-	// Spawn the primary racer.
-	go dialSerialAsync(ctx, primaries, nil, cancel, results)
-
-	// Spawn the fallback racer.
-	fallbackTimer := time.NewTimer(ctx.fallbackDelay())
-	go dialSerialAsync(ctx, fallbacks, fallbackTimer, cancel, results)
-
-	var primaryErr error
-	for nracers := 2; nracers > 0; nracers-- {
-		res := <-results
-		// If we're still waiting for a connection, then hasten the delay.
-		// Otherwise, disable the Timer and let cancel take over.
-		if fallbackTimer.Stop() && res.error != nil {
-			fallbackTimer.Reset(0)
-		}
-		if res.error == nil {
-			return res.Conn, nil
-		}
-		if res.primary {
-			primaryErr = res.error
-		}
+func dialParallel(ctx context.Context, dp *dialParam, primaries, fallbacks addrList) (Conn, error) {
+	if len(fallbacks) == 0 {
+		return dialSerial(ctx, dp, primaries)
 	}
-	return nil, primaryErr
-}
 
-type dialResult struct {
-	Conn
-	error
-	primary bool
-}
+	returned := make(chan struct{})
+	defer close(returned)
+
+	type dialResult struct {
+		Conn
+		error
+		primary bool
+		done    bool
+	}
+	results := make(chan dialResult) // unbuffered
 
-// dialSerialAsync runs dialSerial after some delay, and returns the
-// resulting connection through a channel. When racing two connections,
-// the primary goroutine uses a nil timer to omit the delay.
-func dialSerialAsync(ctx *dialContext, ras addrList, timer *time.Timer, cancel <-chan struct{}, results chan<- dialResult) {
-	if timer != nil {
-		// We're in the fallback goroutine; sleep before connecting.
+	startRacer := func(ctx context.Context, primary bool) {
+		ras := primaries
+		if !primary {
+			ras = fallbacks
+		}
+		c, err := dialSerial(ctx, dp, ras)
 		select {
-		case <-timer.C:
-		case <-cancel:
-			return
+		case results <- dialResult{Conn: c, error: err, primary: primary, done: true}:
+		case <-returned:
+			if c != nil {
+				c.Close()
+			}
 		}
 	}
-	c, err := dialSerial(ctx, ras, cancel)
-	select {
-	case results <- dialResult{c, err, timer == nil}:
-		// We won the race.
-	case <-cancel:
-		// The other goroutine won the race.
-		if c != nil {
-			c.Close()
+
+	var primary, fallback dialResult
+
+	// Start the main racer.
+	primaryCtx, primaryCancel := context.WithCancel(ctx)
+	defer primaryCancel()
+	go startRacer(primaryCtx, true)
+
+	// Start the timer for the fallback racer.
+	fallbackTimer := time.NewTimer(dp.fallbackDelay())
+	defer fallbackTimer.Stop()
+
+	for {
+		select {
+		case <-fallbackTimer.C:
+			fallbackCtx, fallbackCancel := context.WithCancel(ctx)
+			defer fallbackCancel()
+			go startRacer(fallbackCtx, false)
+
+		case res := <-results:
+			if res.error == nil {
+				return res.Conn, nil
+			}
+			if res.primary {
+				primary = res
+			} else {
+				fallback = res
+			}
+			if primary.done && fallback.done {
+				return nil, primary.error
+			}
+			if res.primary && fallbackTimer.Stop() {
+				// If we were able to stop the timer, that means it
+				// was running (hadn't yet started the fallback), but
+				// we just got an error on the primary path, so start
+				// the fallback immediately (in 0 nanoseconds).
+				fallbackTimer.Reset(0)
+			}
 		}
 	}
 }
 
 // dialSerial connects to a list of addresses in sequence, returning
 // either the first successful connection, or the first error.
-func dialSerial(ctx *dialContext, ras addrList, cancel <-chan struct{}) (Conn, error) {
+func dialSerial(ctx context.Context, dp *dialParam, ras addrList) (Conn, error) {
 	var firstErr error // The error from the first address is most relevant.
 
 	for i, ra := range ras {
 		select {
-		case <-cancel:
-			return nil, &OpError{Op: "dial", Net: ctx.network, Source: ctx.LocalAddr, Addr: ra, Err: errCanceled}
+		case <-ctx.Done():
+			return nil, &OpError{Op: "dial", Net: dp.network, Source: dp.LocalAddr, Addr: ra, Err: mapErr(ctx.Err())}
 		default:
 		}
 
-		partialDeadline, err := partialDeadline(time.Now(), ctx.finalDeadline, len(ras)-i)
+		deadline, _ := ctx.Deadline()
+		partialDeadline, err := partialDeadline(time.Now(), deadline, len(ras)-i)
 		if err != nil {
 			// Ran out of time.
 			if firstErr == nil {
-				firstErr = &OpError{Op: "dial", Net: ctx.network, Source: ctx.LocalAddr, Addr: ra, Err: err}
+				firstErr = &OpError{Op: "dial", Net: dp.network, Source: dp.LocalAddr, Addr: ra, Err: err}
 			}
 			break
 		}
-
-		// dialTCP does not support cancelation (see golang.org/issue/11225),
-		// so if cancel fires, we'll continue trying to connect until the next
-		// timeout, or return a spurious connection for the caller to close.
-		dialer := func(d time.Time) (Conn, error) {
-			return dialSingle(ctx, ra, d)
+		dialCtx := ctx
+		if partialDeadline.Before(deadline) {
+			var cancel context.CancelFunc
+			dialCtx, cancel = context.WithDeadline(ctx, partialDeadline)
+			defer cancel()
 		}
-		c, err := dial(ctx.network, ra, dialer, partialDeadline)
+
+		c, err := dialSingle(dialCtx, dp, ra)
 		if err == nil {
 			return c, nil
 		}
@@ -352,37 +476,43 @@ func dialSerial(ctx *dialContext, ras addrList, cancel <-chan struct{}) (Conn, e
 	}
 
 	if firstErr == nil {
-		firstErr = &OpError{Op: "dial", Net: ctx.network, Source: nil, Addr: nil, Err: errMissingAddress}
+		firstErr = &OpError{Op: "dial", Net: dp.network, Source: nil, Addr: nil, Err: errMissingAddress}
 	}
 	return nil, firstErr
 }
 
 // dialSingle attempts to establish and returns a single connection to
-// the destination address. This must be called through the OS-specific
-// dial function, because some OSes don't implement the deadline feature.
-func dialSingle(ctx *dialContext, ra Addr, deadline time.Time) (c Conn, err error) {
-	la := ctx.LocalAddr
-	if la != nil && la.Network() != ra.Network() {
-		return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: errors.New("mismatched local address type " + la.Network())}
+// the destination address.
+func dialSingle(ctx context.Context, dp *dialParam, ra Addr) (c Conn, err error) {
+	trace, _ := ctx.Value(nettrace.TraceKey{}).(*nettrace.Trace)
+	if trace != nil {
+		raStr := ra.String()
+		if trace.ConnectStart != nil {
+			trace.ConnectStart(dp.network, raStr)
+		}
+		if trace.ConnectDone != nil {
+			defer func() { trace.ConnectDone(dp.network, raStr, err) }()
+		}
 	}
+	la := dp.LocalAddr
 	switch ra := ra.(type) {
 	case *TCPAddr:
 		la, _ := la.(*TCPAddr)
-		c, err = testHookDialTCP(ctx.network, la, ra, deadline, ctx.Cancel)
+		c, err = dialTCP(ctx, dp.network, la, ra)
 	case *UDPAddr:
 		la, _ := la.(*UDPAddr)
-		c, err = dialUDP(ctx.network, la, ra, deadline)
+		c, err = dialUDP(ctx, dp.network, la, ra)
 	case *IPAddr:
 		la, _ := la.(*IPAddr)
-		c, err = dialIP(ctx.network, la, ra, deadline)
+		c, err = dialIP(ctx, dp.network, la, ra)
 	case *UnixAddr:
 		la, _ := la.(*UnixAddr)
-		c, err = dialUnix(ctx.network, la, ra, deadline)
+		c, err = dialUnix(ctx, dp.network, la, ra)
 	default:
-		return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: ctx.address}}
+		return nil, &OpError{Op: "dial", Net: dp.network, Source: la, Addr: ra, Err: &AddrError{Err: "unexpected address type", Addr: dp.address}}
 	}
 	if err != nil {
-		return nil, err // c is non-nil interface containing nil pointer
+		return nil, &OpError{Op: "dial", Net: dp.network, Source: la, Addr: ra, Err: err} // c is non-nil interface containing nil pointer
 	}
 	return c, nil
 }
@@ -395,7 +525,7 @@ func dialSingle(ctx *dialContext, ra Addr, deadline time.Time) (c Conn, err erro
 // instead of just the interface with the given host address.
 // See Dial for more details about address syntax.
 func Listen(net, laddr string) (Listener, error) {
-	addrs, err := resolveAddrList("listen", net, laddr, noDeadline)
+	addrs, err := resolveAddrList(context.Background(), "listen", net, laddr, nil)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: err}
 	}
@@ -422,7 +552,7 @@ func Listen(net, laddr string) (Listener, error) {
 // instead of just the interface with the given host address.
 // See Dial for the syntax of laddr.
 func ListenPacket(net, laddr string) (PacketConn, error) {
-	addrs, err := resolveAddrList("listen", net, laddr, noDeadline)
+	addrs, err := resolveAddrList(context.Background(), "listen", net, laddr, nil)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: err}
 	}
diff --git a/libgo/go/net/dial_gen.go b/libgo/go/net/dial_gen.go
deleted file mode 100644
index a628f714835..00000000000
--- a/libgo/go/net/dial_gen.go
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build windows plan9
-
-package net
-
-import "time"
-
-// dialChannel is the simple pure-Go implementation of dial, still
-// used on operating systems where the deadline hasn't been pushed
-// down into the pollserver. (Plan 9 and some old versions of Windows)
-func dialChannel(net string, ra Addr, dialer func(time.Time) (Conn, error), deadline time.Time) (Conn, error) {
-	if deadline.IsZero() {
-		return dialer(noDeadline)
-	}
-	timeout := deadline.Sub(time.Now())
-	if timeout <= 0 {
-		return nil, &OpError{Op: "dial", Net: net, Source: nil, Addr: ra, Err: errTimeout}
-	}
-	t := time.NewTimer(timeout)
-	defer t.Stop()
-	type racer struct {
-		Conn
-		error
-	}
-	ch := make(chan racer, 1)
-	go func() {
-		testHookDialChannel()
-		c, err := dialer(noDeadline)
-		ch <- racer{c, err}
-	}()
-	select {
-	case <-t.C:
-		return nil, &OpError{Op: "dial", Net: net, Source: nil, Addr: ra, Err: errTimeout}
-	case racer := <-ch:
-		return racer.Conn, racer.error
-	}
-}
diff --git a/libgo/go/net/dial_test.go b/libgo/go/net/dial_test.go
index 2311b108241..8b21e6b0886 100644
--- a/libgo/go/net/dial_test.go
+++ b/libgo/go/net/dial_test.go
@@ -5,6 +5,8 @@
 package net
 
 import (
+	"bufio"
+	"context"
 	"internal/testenv"
 	"io"
 	"net/internal/socktest"
@@ -23,13 +25,12 @@ var prohibitionaryDialArgTests = []struct {
 }
 
 func TestProhibitionaryDialArg(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
 	}
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
 	if !supportsIPv4map {
 		t.Skip("mapping ipv4 address inside ipv6 address not supported")
 	}
@@ -54,56 +55,12 @@ func TestProhibitionaryDialArg(t *testing.T) {
 	}
 }
 
-func TestSelfConnect(t *testing.T) {
-	if runtime.GOOS == "windows" {
-		// TODO(brainman): do not know why it hangs.
-		t.Skip("known-broken test on windows")
-	}
-
-	// Test that Dial does not honor self-connects.
-	// See the comment in DialTCP.
-
-	// Find a port that would be used as a local address.
-	l, err := Listen("tcp", "127.0.0.1:0")
-	if err != nil {
-		t.Fatal(err)
-	}
-	c, err := Dial("tcp", l.Addr().String())
-	if err != nil {
-		t.Fatal(err)
-	}
-	addr := c.LocalAddr().String()
-	c.Close()
-	l.Close()
-
-	// Try to connect to that address repeatedly.
-	n := 100000
-	if testing.Short() {
-		n = 1000
-	}
-	switch runtime.GOOS {
-	case "darwin", "dragonfly", "freebsd", "netbsd", "openbsd", "plan9", "solaris", "windows":
-		// Non-Linux systems take a long time to figure
-		// out that there is nothing listening on localhost.
-		n = 100
-	}
-	for i := 0; i < n; i++ {
-		c, err := DialTimeout("tcp", addr, time.Millisecond)
-		if err == nil {
-			if c.LocalAddr().String() == addr {
-				t.Errorf("#%d: Dial %q self-connect", i, addr)
-			} else {
-				t.Logf("#%d: Dial %q succeeded - possibly racing with other listener", i, addr)
-			}
-			c.Close()
-		}
-	}
-}
-
 func TestDialTimeoutFDLeak(t *testing.T) {
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skipf("%s does not have full support of socktest", runtime.GOOS)
+	case "openbsd":
+		testenv.SkipFlaky(t, 15157)
 	}
 
 	const T = 100 * time.Millisecond
@@ -130,17 +87,14 @@ func TestDialTimeoutFDLeak(t *testing.T) {
 	// socktest.Switch.
 	// It may happen when the Dial call bumps against TCP
 	// simultaneous open. See selfConnect in tcpsock_posix.go.
-	defer func() {
-		sw.Set(socktest.FilterClose, nil)
-		forceCloseSockets()
-	}()
+	defer func() { sw.Set(socktest.FilterClose, nil) }()
 	var mu sync.Mutex
 	var attempts int
 	sw.Set(socktest.FilterClose, func(so *socktest.Status) (socktest.AfterFilter, error) {
 		mu.Lock()
 		attempts++
 		mu.Unlock()
-		return nil, errTimedout
+		return nil, nil
 	})
 
 	const N = 100
@@ -176,6 +130,12 @@ func TestDialerDualStackFDLeak(t *testing.T) {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
 
+	closedPortDelay, expectClosedPortDelay := dialClosedPort()
+	if closedPortDelay > expectClosedPortDelay {
+		t.Errorf("got %v; want <= %v", closedPortDelay, expectClosedPortDelay)
+	}
+
+	before := sw.Sockets()
 	origTestHookLookupIP := testHookLookupIP
 	defer func() { testHookLookupIP = origTestHookLookupIP }()
 	testHookLookupIP = lookupLocalhost
@@ -188,24 +148,19 @@ func TestDialerDualStackFDLeak(t *testing.T) {
 			c.Close()
 		}
 	}
-	dss, err := newDualStackServer([]streamListener{
-		{network: "tcp4", address: "127.0.0.1"},
-		{network: "tcp6", address: "::1"},
-	})
+	dss, err := newDualStackServer()
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer dss.teardown()
 	if err := dss.buildup(handler); err != nil {
+		dss.teardown()
 		t.Fatal(err)
 	}
 
-	before := sw.Sockets()
-	const T = 100 * time.Millisecond
 	const N = 10
 	var wg sync.WaitGroup
 	wg.Add(N)
-	d := &Dialer{DualStack: true, Timeout: T}
+	d := &Dialer{DualStack: true, Timeout: 100*time.Millisecond + closedPortDelay}
 	for i := 0; i < N; i++ {
 		go func() {
 			defer wg.Done()
@@ -218,7 +173,7 @@ func TestDialerDualStackFDLeak(t *testing.T) {
 		}()
 	}
 	wg.Wait()
-	time.Sleep(2 * T) // wait for the dial racers to stop
+	dss.teardown()
 	after := sw.Sockets()
 	if len(after) != len(before) {
 		t.Errorf("got %d; want %d", len(after), len(before))
@@ -229,18 +184,18 @@ func TestDialerDualStackFDLeak(t *testing.T) {
 // expected to hang until the timeout elapses. These addresses are reserved
 // for benchmarking by RFC 6890.
 const (
-	slowDst4    = "192.18.0.254"
-	slowDst6    = "2001:2::254"
-	slowTimeout = 1 * time.Second
+	slowDst4 = "198.18.0.254"
+	slowDst6 = "2001:2::254"
 )
 
 // In some environments, the slow IPs may be explicitly unreachable, and fail
 // more quickly than expected. This test hook prevents dialTCP from returning
 // before the deadline.
-func slowDialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-chan struct{}) (*TCPConn, error) {
-	c, err := dialTCP(net, laddr, raddr, deadline, cancel)
+func slowDialTCP(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+	c, err := doDialTCP(ctx, net, laddr, raddr)
 	if ParseIP(slowDst4).Equal(raddr.IP) || ParseIP(slowDst6).Equal(raddr.IP) {
-		time.Sleep(deadline.Sub(time.Now()))
+		// Wait for the deadline, or indefinitely if none exists.
+		<-ctx.Done()
 	}
 	return c, err
 }
@@ -278,9 +233,8 @@ func dialClosedPort() (actual, expected time.Duration) {
 }
 
 func TestDialParallel(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
+
 	if !supportsIPv4 || !supportsIPv6 {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
@@ -294,7 +248,7 @@ func TestDialParallel(t *testing.T) {
 	const fallbackDelay = 200 * time.Millisecond
 
 	// Some cases will run quickly when "connection refused" is fast,
-	// or trigger the fallbackDelay on Windows.  This value holds the
+	// or trigger the fallbackDelay on Windows. This value holds the
 	// lesser of the two delays.
 	var closedPortOrFallbackDelay time.Duration
 	if closedPortDelay < fallbackDelay {
@@ -369,10 +323,7 @@ func TestDialParallel(t *testing.T) {
 	}
 
 	for i, tt := range testCases {
-		dss, err := newDualStackServer([]streamListener{
-			{network: "tcp4", address: "127.0.0.1"},
-			{network: "tcp6", address: "::1"},
-		})
+		dss, err := newDualStackServer()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -389,17 +340,15 @@ func TestDialParallel(t *testing.T) {
 		fallbacks := makeAddrs(tt.fallbacks, dss.port)
 		d := Dialer{
 			FallbackDelay: fallbackDelay,
-			Timeout:       slowTimeout,
-		}
-		ctx := &dialContext{
-			Dialer:        d,
-			network:       "tcp",
-			address:       "?",
-			finalDeadline: d.deadline(time.Now()),
 		}
 		startTime := time.Now()
-		c, err := dialParallel(ctx, primaries, fallbacks)
-		elapsed := time.Now().Sub(startTime)
+		dp := &dialParam{
+			Dialer:  d,
+			network: "tcp",
+			address: "?",
+		}
+		c, err := dialParallel(context.Background(), dp, primaries, fallbacks)
+		elapsed := time.Since(startTime)
 
 		if c != nil {
 			c.Close()
@@ -418,12 +367,30 @@ func TestDialParallel(t *testing.T) {
 		} else if !(elapsed <= expectElapsedMax) {
 			t.Errorf("#%d: got %v; want <= %v", i, elapsed, expectElapsedMax)
 		}
+
+		// Repeat each case, ensuring that it can be canceled quickly.
+		ctx, cancel := context.WithCancel(context.Background())
+		var wg sync.WaitGroup
+		wg.Add(1)
+		go func() {
+			time.Sleep(5 * time.Millisecond)
+			cancel()
+			wg.Done()
+		}()
+		startTime = time.Now()
+		c, err = dialParallel(ctx, dp, primaries, fallbacks)
+		if c != nil {
+			c.Close()
+		}
+		elapsed = time.Now().Sub(startTime)
+		if elapsed > 100*time.Millisecond {
+			t.Errorf("#%d (cancel): got %v; want <= 100ms", i, elapsed)
+		}
+		wg.Wait()
 	}
-	// Wait for any slowDst4/slowDst6 connections to timeout.
-	time.Sleep(slowTimeout * 3 / 2)
 }
 
-func lookupSlowFast(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+func lookupSlowFast(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
 	switch host {
 	case "slow6loopback4":
 		// Returns a slow IPv6 address, and a local IPv4 address.
@@ -432,14 +399,13 @@ func lookupSlowFast(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, e
 			{IP: ParseIP("127.0.0.1")},
 		}, nil
 	default:
-		return fn(host)
+		return fn(ctx, host)
 	}
 }
 
 func TestDialerFallbackDelay(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
+
 	if !supportsIPv4 || !supportsIPv6 {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
@@ -463,8 +429,6 @@ func TestDialerFallbackDelay(t *testing.T) {
 		{true, 200 * time.Millisecond, 200 * time.Millisecond},
 		// The default is 300ms.
 		{true, 0, 300 * time.Millisecond},
-		// This case is last, in order to wait for hanging slowDst6 connections.
-		{false, 0, slowTimeout},
 	}
 
 	handler := func(dss *dualStackServer, ln Listener) {
@@ -476,9 +440,7 @@ func TestDialerFallbackDelay(t *testing.T) {
 			c.Close()
 		}
 	}
-	dss, err := newDualStackServer([]streamListener{
-		{network: "tcp", address: "127.0.0.1"},
-	})
+	dss, err := newDualStackServer()
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -488,7 +450,7 @@ func TestDialerFallbackDelay(t *testing.T) {
 	}
 
 	for i, tt := range testCases {
-		d := &Dialer{DualStack: tt.dualstack, FallbackDelay: tt.delay, Timeout: slowTimeout}
+		d := &Dialer{DualStack: tt.dualstack, FallbackDelay: tt.delay}
 
 		startTime := time.Now()
 		c, err := d.Dial("tcp", JoinHostPort("slow6loopback4", dss.port))
@@ -509,46 +471,78 @@ func TestDialerFallbackDelay(t *testing.T) {
 	}
 }
 
-func TestDialSerialAsyncSpuriousConnection(t *testing.T) {
-	if runtime.GOOS == "plan9" {
-		t.Skip("skipping on plan9; no deadline support, golang.org/issue/11932")
+func TestDialParallelSpuriousConnection(t *testing.T) {
+	if !supportsIPv4 || !supportsIPv6 {
+		t.Skip("both IPv4 and IPv6 are required")
 	}
-	ln, err := newLocalListener("tcp")
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	handler := func(dss *dualStackServer, ln Listener) {
+		// Accept one connection per address.
+		c, err := ln.Accept()
+		if err != nil {
+			t.Fatal(err)
+		}
+		// The client should close itself, without sending data.
+		c.SetReadDeadline(time.Now().Add(1 * time.Second))
+		var b [1]byte
+		if _, err := c.Read(b[:]); err != io.EOF {
+			t.Errorf("got %v; want %v", err, io.EOF)
+		}
+		c.Close()
+		wg.Done()
+	}
+	dss, err := newDualStackServer()
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer ln.Close()
+	defer dss.teardown()
+	if err := dss.buildup(handler); err != nil {
+		t.Fatal(err)
+	}
+
+	const fallbackDelay = 100 * time.Millisecond
+
+	origTestHookDialTCP := testHookDialTCP
+	defer func() { testHookDialTCP = origTestHookDialTCP }()
+	testHookDialTCP = func(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+		// Sleep long enough for Happy Eyeballs to kick in, and inhibit cancelation.
+		// This forces dialParallel to juggle two successful connections.
+		time.Sleep(fallbackDelay * 2)
 
-	d := Dialer{}
-	ctx := &dialContext{
-		Dialer:        d,
-		network:       "tcp",
-		address:       "?",
-		finalDeadline: d.deadline(time.Now()),
+		// Now ignore the provided context (which will be canceled) and use a
+		// different one to make sure this completes with a valid connection,
+		// which we hope to be closed below:
+		return doDialTCP(context.Background(), net, laddr, raddr)
 	}
 
-	results := make(chan dialResult)
-	cancel := make(chan struct{})
+	d := Dialer{
+		FallbackDelay: fallbackDelay,
+	}
+	dp := &dialParam{
+		Dialer:  d,
+		network: "tcp",
+		address: "?",
+	}
 
-	// Spawn a connection in the background.
-	go dialSerialAsync(ctx, addrList{ln.Addr()}, nil, cancel, results)
+	makeAddr := func(ip string) addrList {
+		addr, err := ResolveTCPAddr("tcp", JoinHostPort(ip, dss.port))
+		if err != nil {
+			t.Fatal(err)
+		}
+		return addrList{addr}
+	}
 
-	// Receive it at the server.
-	c, err := ln.Accept()
+	// dialParallel returns one connection (and closes the other.)
+	c, err := dialParallel(context.Background(), dp, makeAddr("127.0.0.1"), makeAddr("::1"))
 	if err != nil {
 		t.Fatal(err)
 	}
-	defer c.Close()
-
-	// Tell dialSerialAsync that someone else won the race.
-	close(cancel)
+	c.Close()
 
-	// The connection should close itself, without sending data.
-	c.SetReadDeadline(time.Now().Add(1 * time.Second))
-	var b [1]byte
-	if _, err := c.Read(b[:]); err != io.EOF {
-		t.Errorf("got %v; want %v", err, io.EOF)
-	}
+	// The server should've seen both connections.
+	wg.Wait()
 }
 
 func TestDialerPartialDeadline(t *testing.T) {
@@ -587,44 +581,125 @@ func TestDialerPartialDeadline(t *testing.T) {
 }
 
 func TestDialerLocalAddr(t *testing.T) {
-	ch := make(chan error, 1)
-	handler := func(ls *localServer, ln Listener) {
-		c, err := ln.Accept()
-		if err != nil {
-			ch <- err
-			return
-		}
-		defer c.Close()
-		ch <- nil
-	}
-	ls, err := newLocalServer("tcp")
-	if err != nil {
-		t.Fatal(err)
+	if !supportsIPv4 || !supportsIPv6 {
+		t.Skip("both IPv4 and IPv6 are required")
 	}
-	defer ls.teardown()
-	if err := ls.buildup(handler); err != nil {
-		t.Fatal(err)
+
+	type test struct {
+		network, raddr string
+		laddr          Addr
+		error
+	}
+	var tests = []test{
+		{"tcp4", "127.0.0.1", nil, nil},
+		{"tcp4", "127.0.0.1", &TCPAddr{}, nil},
+		{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+		{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+		{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, &AddrError{Err: "some error"}},
+		{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, nil},
+		{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, nil},
+		{"tcp4", "127.0.0.1", &TCPAddr{IP: IPv6loopback}, errNoSuitableAddress},
+		{"tcp4", "127.0.0.1", &UDPAddr{}, &AddrError{Err: "some error"}},
+		{"tcp4", "127.0.0.1", &UnixAddr{}, &AddrError{Err: "some error"}},
+
+		{"tcp6", "::1", nil, nil},
+		{"tcp6", "::1", &TCPAddr{}, nil},
+		{"tcp6", "::1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+		{"tcp6", "::1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+		{"tcp6", "::1", &TCPAddr{IP: ParseIP("::")}, nil},
+		{"tcp6", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, errNoSuitableAddress},
+		{"tcp6", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, errNoSuitableAddress},
+		{"tcp6", "::1", &TCPAddr{IP: IPv6loopback}, nil},
+		{"tcp6", "::1", &UDPAddr{}, &AddrError{Err: "some error"}},
+		{"tcp6", "::1", &UnixAddr{}, &AddrError{Err: "some error"}},
+
+		{"tcp", "127.0.0.1", nil, nil},
+		{"tcp", "127.0.0.1", &TCPAddr{}, nil},
+		{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+		{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+		{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, nil},
+		{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, nil},
+		{"tcp", "127.0.0.1", &TCPAddr{IP: IPv6loopback}, errNoSuitableAddress},
+		{"tcp", "127.0.0.1", &UDPAddr{}, &AddrError{Err: "some error"}},
+		{"tcp", "127.0.0.1", &UnixAddr{}, &AddrError{Err: "some error"}},
+
+		{"tcp", "::1", nil, nil},
+		{"tcp", "::1", &TCPAddr{}, nil},
+		{"tcp", "::1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+		{"tcp", "::1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+		{"tcp", "::1", &TCPAddr{IP: ParseIP("::")}, nil},
+		{"tcp", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, errNoSuitableAddress},
+		{"tcp", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, errNoSuitableAddress},
+		{"tcp", "::1", &TCPAddr{IP: IPv6loopback}, nil},
+		{"tcp", "::1", &UDPAddr{}, &AddrError{Err: "some error"}},
+		{"tcp", "::1", &UnixAddr{}, &AddrError{Err: "some error"}},
+	}
+
+	if supportsIPv4map {
+		tests = append(tests, test{
+			"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, nil,
+		})
+	} else {
+		tests = append(tests, test{
+			"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, &AddrError{Err: "some error"},
+		})
 	}
 
-	laddr, err := ResolveTCPAddr(ls.Listener.Addr().Network(), ls.Listener.Addr().String())
-	if err != nil {
-		t.Fatal(err)
+	origTestHookLookupIP := testHookLookupIP
+	defer func() { testHookLookupIP = origTestHookLookupIP }()
+	testHookLookupIP = lookupLocalhost
+	handler := func(ls *localServer, ln Listener) {
+		for {
+			c, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			c.Close()
+		}
 	}
-	laddr.Port = 0
-	d := &Dialer{LocalAddr: laddr}
-	c, err := d.Dial(ls.Listener.Addr().Network(), ls.Addr().String())
-	if err != nil {
-		t.Fatal(err)
+	var err error
+	var lss [2]*localServer
+	for i, network := range []string{"tcp4", "tcp6"} {
+		lss[i], err = newLocalServer(network)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer lss[i].teardown()
+		if err := lss[i].buildup(handler); err != nil {
+			t.Fatal(err)
+		}
 	}
-	defer c.Close()
-	c.Read(make([]byte, 1))
-	err = <-ch
-	if err != nil {
-		t.Error(err)
+
+	for _, tt := range tests {
+		d := &Dialer{LocalAddr: tt.laddr}
+		var addr string
+		ip := ParseIP(tt.raddr)
+		if ip.To4() != nil {
+			addr = lss[0].Listener.Addr().String()
+		}
+		if ip.To16() != nil && ip.To4() == nil {
+			addr = lss[1].Listener.Addr().String()
+		}
+		c, err := d.Dial(tt.network, addr)
+		if err == nil && tt.error != nil || err != nil && tt.error == nil {
+			t.Errorf("%s %v->%s: got %v; want %v", tt.network, tt.laddr, tt.raddr, err, tt.error)
+		}
+		if err != nil {
+			if perr := parseDialError(err); perr != nil {
+				t.Error(perr)
+			}
+			continue
+		}
+		c.Close()
 	}
 }
 
 func TestDialerDualStack(t *testing.T) {
+	// This test is known to be flaky. Don't frighten regular
+	// users about it; only fail on the build dashboard.
+	if testenv.Builder() == "" {
+		testenv.SkipFlaky(t, 13324)
+	}
 	if !supportsIPv4 || !supportsIPv6 {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
@@ -649,10 +724,7 @@ func TestDialerDualStack(t *testing.T) {
 
 	var timeout = 150*time.Millisecond + closedPortDelay
 	for _, dualstack := range []bool{false, true} {
-		dss, err := newDualStackServer([]streamListener{
-			{network: "tcp4", address: "127.0.0.1"},
-			{network: "tcp6", address: "::1"},
-		})
+		dss, err := newDualStackServer()
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -677,7 +749,6 @@ func TestDialerDualStack(t *testing.T) {
 			c.Close()
 		}
 	}
-	time.Sleep(timeout * 3 / 2) // wait for the dial racers to stop
 }
 
 func TestDialerKeepAlive(t *testing.T) {
@@ -719,14 +790,16 @@ func TestDialerKeepAlive(t *testing.T) {
 }
 
 func TestDialCancel(t *testing.T) {
-	if runtime.GOOS == "plan9" || runtime.GOOS == "nacl" {
-		// plan9 is not implemented and nacl doesn't have
-		// external network access.
-		t.Skipf("skipping on %s", runtime.GOOS)
+	switch testenv.Builder() {
+	case "linux-arm64-buildlet":
+		t.Skip("skipping on linux-arm64-buildlet; incompatible network config? issue 15191")
+	case "":
+		testenv.MustHaveExternalNetwork(t)
 	}
-	onGoBuildFarm := testenv.Builder() != ""
-	if testing.Short() && !onGoBuildFarm {
-		t.Skip("skipping in short mode")
+
+	if runtime.GOOS == "nacl" {
+		// nacl doesn't have external network access.
+		t.Skipf("skipping on %s", runtime.GOOS)
 	}
 
 	blackholeIPPort := JoinHostPort(slowDst4, "1234")
@@ -781,3 +854,84 @@ func TestDialCancel(t *testing.T) {
 		}
 	}
 }
+
+func TestCancelAfterDial(t *testing.T) {
+	if testing.Short() {
+		t.Skip("avoiding time.Sleep")
+	}
+
+	ln, err := newLocalListener("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	defer func() {
+		ln.Close()
+		wg.Wait()
+	}()
+
+	// Echo back the first line of each incoming connection.
+	go func() {
+		for {
+			c, err := ln.Accept()
+			if err != nil {
+				break
+			}
+			rb := bufio.NewReader(c)
+			line, err := rb.ReadString('\n')
+			if err != nil {
+				t.Error(err)
+				c.Close()
+				continue
+			}
+			if _, err := c.Write([]byte(line)); err != nil {
+				t.Error(err)
+			}
+			c.Close()
+		}
+		wg.Done()
+	}()
+
+	try := func() {
+		cancel := make(chan struct{})
+		d := &Dialer{Cancel: cancel}
+		c, err := d.Dial("tcp", ln.Addr().String())
+
+		// Immediately after dialing, request cancelation and sleep.
+		// Before Issue 15078 was fixed, this would cause subsequent operations
+		// to fail with an i/o timeout roughly 50% of the time.
+		close(cancel)
+		time.Sleep(10 * time.Millisecond)
+
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer c.Close()
+
+		// Send some data to confirm that the connection is still alive.
+		const message = "echo!\n"
+		if _, err := c.Write([]byte(message)); err != nil {
+			t.Fatal(err)
+		}
+
+		// The server should echo the line, and close the connection.
+		rb := bufio.NewReader(c)
+		line, err := rb.ReadString('\n')
+		if err != nil {
+			t.Fatal(err)
+		}
+		if line != message {
+			t.Errorf("got %q; want %q", line, message)
+		}
+		if _, err := rb.ReadByte(); err != io.EOF {
+			t.Errorf("got %v; want %v", err, io.EOF)
+		}
+	}
+
+	// This bug manifested about 50% of the time, so try it a few times.
+	for i := 0; i < 10; i++ {
+		try()
+	}
+}
diff --git a/libgo/go/net/dnsclient.go b/libgo/go/net/dnsclient.go
index 5dc2a0368ce..f1835b8c060 100644
--- a/libgo/go/net/dnsclient.go
+++ b/libgo/go/net/dnsclient.go
@@ -45,7 +45,7 @@ func answer(name, server string, dns *dnsMsg, qtype uint16) (cname string, addrs
 	}
 	if dns.rcode != dnsRcodeSuccess {
 		// None of the error codes make sense
-		// for the query we sent.  If we didn't get
+		// for the query we sent. If we didn't get
 		// a name error and we didn't get success,
 		// the server is behaving incorrectly or
 		// having temporary trouble.
@@ -161,7 +161,7 @@ func isDomainName(s string) bool {
 	return ok
 }
 
-// absDomainName returns an absoulte domain name which ends with a
+// absDomainName returns an absolute domain name which ends with a
 // trailing dot to match pure Go reverse resolver and all other lookup
 // routines.
 // See golang.org/issue/12189.
diff --git a/libgo/go/net/dnsclient_unix.go b/libgo/go/net/dnsclient_unix.go
index 17188f0024c..8f2dff46751 100644
--- a/libgo/go/net/dnsclient_unix.go
+++ b/libgo/go/net/dnsclient_unix.go
@@ -16,6 +16,7 @@
 package net
 
 import (
+	"context"
 	"errors"
 	"io"
 	"math/rand"
@@ -26,10 +27,10 @@ import (
 
 // A dnsDialer provides dialing suitable for DNS queries.
 type dnsDialer interface {
-	dialDNS(string, string) (dnsConn, error)
+	dialDNS(ctx context.Context, network, addr string) (dnsConn, error)
 }
 
-var testHookDNSDialer = func(d time.Duration) dnsDialer { return &Dialer{Timeout: d} }
+var testHookDNSDialer = func() dnsDialer { return &Dialer{} }
 
 // A dnsConn represents a DNS transport endpoint.
 type dnsConn interface {
@@ -37,46 +38,67 @@ type dnsConn interface {
 
 	SetDeadline(time.Time) error
 
-	// readDNSResponse reads a DNS response message from the DNS
-	// transport endpoint and returns the received DNS response
-	// message.
-	readDNSResponse() (*dnsMsg, error)
+	// dnsRoundTrip executes a single DNS transaction, returning a
+	// DNS response message for the provided DNS query message.
+	dnsRoundTrip(query *dnsMsg) (*dnsMsg, error)
+}
 
-	// writeDNSQuery writes a DNS query message to the DNS
-	// connection endpoint.
-	writeDNSQuery(*dnsMsg) error
+func (c *UDPConn) dnsRoundTrip(query *dnsMsg) (*dnsMsg, error) {
+	return dnsRoundTripUDP(c, query)
 }
 
-func (c *UDPConn) readDNSResponse() (*dnsMsg, error) {
-	b := make([]byte, 512) // see RFC 1035
-	n, err := c.Read(b)
-	if err != nil {
+// dnsRoundTripUDP implements the dnsRoundTrip interface for RFC 1035's
+// "UDP usage" transport mechanism. c should be a packet-oriented connection,
+// such as a *UDPConn.
+func dnsRoundTripUDP(c io.ReadWriter, query *dnsMsg) (*dnsMsg, error) {
+	b, ok := query.Pack()
+	if !ok {
+		return nil, errors.New("cannot marshal DNS message")
+	}
+	if _, err := c.Write(b); err != nil {
 		return nil, err
 	}
-	msg := &dnsMsg{}
-	if !msg.Unpack(b[:n]) {
-		return nil, errors.New("cannot unmarshal DNS message")
+
+	b = make([]byte, 512) // see RFC 1035
+	for {
+		n, err := c.Read(b)
+		if err != nil {
+			return nil, err
+		}
+		resp := &dnsMsg{}
+		if !resp.Unpack(b[:n]) || !resp.IsResponseTo(query) {
+			// Ignore invalid responses as they may be malicious
+			// forgery attempts. Instead continue waiting until
+			// timeout. See golang.org/issue/13281.
+			continue
+		}
+		return resp, nil
 	}
-	return msg, nil
 }
 
-func (c *UDPConn) writeDNSQuery(msg *dnsMsg) error {
-	b, ok := msg.Pack()
+func (c *TCPConn) dnsRoundTrip(out *dnsMsg) (*dnsMsg, error) {
+	return dnsRoundTripTCP(c, out)
+}
+
+// dnsRoundTripTCP implements the dnsRoundTrip interface for RFC 1035's
+// "TCP usage" transport mechanism. c should be a stream-oriented connection,
+// such as a *TCPConn.
+func dnsRoundTripTCP(c io.ReadWriter, query *dnsMsg) (*dnsMsg, error) {
+	b, ok := query.Pack()
 	if !ok {
-		return errors.New("cannot marshal DNS message")
+		return nil, errors.New("cannot marshal DNS message")
 	}
+	l := len(b)
+	b = append([]byte{byte(l >> 8), byte(l)}, b...)
 	if _, err := c.Write(b); err != nil {
-		return err
+		return nil, err
 	}
-	return nil
-}
 
-func (c *TCPConn) readDNSResponse() (*dnsMsg, error) {
-	b := make([]byte, 1280) // 1280 is a reasonable initial size for IP over Ethernet, see RFC 4035
+	b = make([]byte, 1280) // 1280 is a reasonable initial size for IP over Ethernet, see RFC 4035
 	if _, err := io.ReadFull(c, b[:2]); err != nil {
 		return nil, err
 	}
-	l := int(b[0])<<8 | int(b[1])
+	l = int(b[0])<<8 | int(b[1])
 	if l > len(b) {
 		b = make([]byte, l)
 	}
@@ -84,27 +106,17 @@ func (c *TCPConn) readDNSResponse() (*dnsMsg, error) {
 	if err != nil {
 		return nil, err
 	}
-	msg := &dnsMsg{}
-	if !msg.Unpack(b[:n]) {
+	resp := &dnsMsg{}
+	if !resp.Unpack(b[:n]) {
 		return nil, errors.New("cannot unmarshal DNS message")
 	}
-	return msg, nil
-}
-
-func (c *TCPConn) writeDNSQuery(msg *dnsMsg) error {
-	b, ok := msg.Pack()
-	if !ok {
-		return errors.New("cannot marshal DNS message")
+	if !resp.IsResponseTo(query) {
+		return nil, errors.New("invalid DNS response")
 	}
-	l := uint16(len(b))
-	b = append([]byte{byte(l >> 8), byte(l)}, b...)
-	if _, err := c.Write(b); err != nil {
-		return err
-	}
-	return nil
+	return resp, nil
 }
 
-func (d *Dialer) dialDNS(network, server string) (dnsConn, error) {
+func (d *Dialer) dialDNS(ctx context.Context, network, server string) (dnsConn, error) {
 	switch network {
 	case "tcp", "tcp4", "tcp6", "udp", "udp4", "udp6":
 	default:
@@ -115,9 +127,9 @@ func (d *Dialer) dialDNS(network, server string) (dnsConn, error) {
 	// call back here to translate it. The DNS config parser has
 	// already checked that all the cfg.servers[i] are IP
 	// addresses, which Dial will use without a DNS lookup.
-	c, err := d.Dial(network, server)
+	c, err := d.DialContext(ctx, network, server)
 	if err != nil {
-		return nil, err
+		return nil, mapErr(err)
 	}
 	switch network {
 	case "tcp", "tcp4", "tcp6":
@@ -129,8 +141,8 @@ func (d *Dialer) dialDNS(network, server string) (dnsConn, error) {
 }
 
 // exchange sends a query on the connection and hopes for a response.
-func exchange(server, name string, qtype uint16, timeout time.Duration) (*dnsMsg, error) {
-	d := testHookDNSDialer(timeout)
+func exchange(ctx context.Context, server, name string, qtype uint16) (*dnsMsg, error) {
+	d := testHookDNSDialer()
 	out := dnsMsg{
 		dnsMsgHdr: dnsMsgHdr{
 			recursion_desired: true,
@@ -140,24 +152,18 @@ func exchange(server, name string, qtype uint16, timeout time.Duration) (*dnsMsg
 		},
 	}
 	for _, network := range []string{"udp", "tcp"} {
-		c, err := d.dialDNS(network, server)
+		c, err := d.dialDNS(ctx, network, server)
 		if err != nil {
 			return nil, err
 		}
 		defer c.Close()
-		if timeout > 0 {
-			c.SetDeadline(time.Now().Add(timeout))
+		if d, ok := ctx.Deadline(); ok && !d.IsZero() {
+			c.SetDeadline(d)
 		}
 		out.id = uint16(rand.Int()) ^ uint16(time.Now().UnixNano())
-		if err := c.writeDNSQuery(&out); err != nil {
-			return nil, err
-		}
-		in, err := c.readDNSResponse()
+		in, err := c.dnsRoundTrip(&out)
 		if err != nil {
-			return nil, err
-		}
-		if in.id != out.id {
-			return nil, errors.New("DNS message ID mismatch")
+			return nil, mapErr(err)
 		}
 		if in.truncated { // see RFC 5966
 			continue
@@ -169,16 +175,22 @@ func exchange(server, name string, qtype uint16, timeout time.Duration) (*dnsMsg
 
 // Do a lookup for a single name, which must be rooted
 // (otherwise answer will not find the answers).
-func tryOneName(cfg *dnsConfig, name string, qtype uint16) (string, []dnsRR, error) {
+func tryOneName(ctx context.Context, cfg *dnsConfig, name string, qtype uint16) (string, []dnsRR, error) {
 	if len(cfg.servers) == 0 {
 		return "", nil, &DNSError{Err: "no DNS servers", Name: name}
 	}
-	timeout := time.Duration(cfg.timeout) * time.Second
+
+	deadline := time.Now().Add(cfg.timeout)
+	if old, ok := ctx.Deadline(); !ok || deadline.Before(old) {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithDeadline(ctx, deadline)
+		defer cancel()
+	}
+
 	var lastErr error
 	for i := 0; i < cfg.attempts; i++ {
 		for _, server := range cfg.servers {
-			server = JoinHostPort(server, "53")
-			msg, err := exchange(server, name, qtype, timeout)
+			msg, err := exchange(ctx, server, name, qtype)
 			if err != nil {
 				lastErr = &DNSError{
 					Err:    err.Error(),
@@ -190,6 +202,12 @@ func tryOneName(cfg *dnsConfig, name string, qtype uint16) (string, []dnsRR, err
 				}
 				continue
 			}
+			// libresolv continues to the next server when it receives
+			// an invalid referral response. See golang.org/issue/15434.
+			if msg.rcode == dnsRcodeSuccess && !msg.authoritative && !msg.recursion_available && len(msg.answer) == 0 && len(msg.extra) == 0 {
+				lastErr = &DNSError{Err: "lame referral", Name: name, Server: server}
+				continue
+			}
 			cname, rrs, err := answer(name, server, msg, qtype)
 			// If answer errored for rcodes dnsRcodeSuccess or dnsRcodeNameError,
 			// it means the response in msg was not useful and trying another
@@ -229,7 +247,6 @@ type resolverConfig struct {
 	// time to recheck resolv.conf.
 	ch          chan struct{} // guards lastChecked and modTime
 	lastChecked time.Time     // last time resolv.conf was checked
-	modTime     time.Time     // time of resolv.conf modification
 
 	mu        sync.RWMutex // protects dnsConfig
 	dnsConfig *dnsConfig   // parsed resolv.conf structure used in lookups
@@ -239,16 +256,12 @@ var resolvConf resolverConfig
 
 // init initializes conf and is only called via conf.initOnce.
 func (conf *resolverConfig) init() {
-	// Set dnsConfig, modTime, and lastChecked so we don't parse
+	// Set dnsConfig and lastChecked so we don't parse
 	// resolv.conf twice the first time.
 	conf.dnsConfig = systemConf().resolv
 	if conf.dnsConfig == nil {
 		conf.dnsConfig = dnsReadConfig("/etc/resolv.conf")
 	}
-
-	if fi, err := os.Stat("/etc/resolv.conf"); err == nil {
-		conf.modTime = fi.ModTime()
-	}
 	conf.lastChecked = time.Now()
 
 	// Prepare ch so that only one update of resolverConfig may
@@ -274,17 +287,12 @@ func (conf *resolverConfig) tryUpdate(name string) {
 	}
 	conf.lastChecked = now
 
+	var mtime time.Time
 	if fi, err := os.Stat(name); err == nil {
-		if fi.ModTime().Equal(conf.modTime) {
-			return
-		}
-		conf.modTime = fi.ModTime()
-	} else {
-		// If modTime wasn't set prior, assume nothing has changed.
-		if conf.modTime.IsZero() {
-			return
-		}
-		conf.modTime = time.Time{}
+		mtime = fi.ModTime()
+	}
+	if mtime.Equal(conf.dnsConfig.mtime) {
+		return
 	}
 
 	dnsConf := dnsReadConfig(name)
@@ -306,7 +314,7 @@ func (conf *resolverConfig) releaseSema() {
 	<-conf.ch
 }
 
-func lookup(name string, qtype uint16) (cname string, rrs []dnsRR, err error) {
+func lookup(ctx context.Context, name string, qtype uint16) (cname string, rrs []dnsRR, err error) {
 	if !isDomainName(name) {
 		return "", nil, &DNSError{Err: "invalid domain name", Name: name}
 	}
@@ -315,7 +323,7 @@ func lookup(name string, qtype uint16) (cname string, rrs []dnsRR, err error) {
 	conf := resolvConf.dnsConfig
 	resolvConf.mu.RUnlock()
 	for _, fqdn := range conf.nameList(name) {
-		cname, rrs, err = tryOneName(conf, fqdn, qtype)
+		cname, rrs, err = tryOneName(ctx, conf, fqdn, qtype)
 		if err == nil {
 			break
 		}
@@ -329,30 +337,47 @@ func lookup(name string, qtype uint16) (cname string, rrs []dnsRR, err error) {
 	return
 }
 
+// avoidDNS reports whether this is a hostname for which we should not
+// use DNS. Currently this includes only .onion and .local names,
+// per RFC 7686 and RFC 6762, respectively. See golang.org/issue/13705.
+func avoidDNS(name string) bool {
+	if name == "" {
+		return true
+	}
+	if name[len(name)-1] == '.' {
+		name = name[:len(name)-1]
+	}
+	return stringsHasSuffixFold(name, ".onion") || stringsHasSuffixFold(name, ".local")
+}
+
 // nameList returns a list of names for sequential DNS queries.
 func (conf *dnsConfig) nameList(name string) []string {
+	if avoidDNS(name) {
+		return nil
+	}
+
 	// If name is rooted (trailing dot), try only that name.
 	rooted := len(name) > 0 && name[len(name)-1] == '.'
 	if rooted {
 		return []string{name}
 	}
+
+	hasNdots := count(name, '.') >= conf.ndots
+	name += "."
+
 	// Build list of search choices.
 	names := make([]string, 0, 1+len(conf.search))
 	// If name has enough dots, try unsuffixed first.
-	if count(name, '.') >= conf.ndots {
-		names = append(names, name+".")
+	if hasNdots {
+		names = append(names, name)
 	}
 	// Try suffixes.
 	for _, suffix := range conf.search {
-		suffixed := name + "." + suffix
-		if suffixed[len(suffixed)-1] != '.' {
-			suffixed += "."
-		}
-		names = append(names, suffixed)
+		names = append(names, name+suffix)
 	}
 	// Try unsuffixed, if not tried first above.
-	if count(name, '.') < conf.ndots {
-		names = append(names, name+".")
+	if !hasNdots {
+		names = append(names, name)
 	}
 	return names
 }
@@ -392,11 +417,11 @@ func (o hostLookupOrder) String() string {
 // Normally we let cgo use the C library resolver instead of
 // depending on our lookup code, so that Go and C get the same
 // answers.
-func goLookupHost(name string) (addrs []string, err error) {
-	return goLookupHostOrder(name, hostLookupFilesDNS)
+func goLookupHost(ctx context.Context, name string) (addrs []string, err error) {
+	return goLookupHostOrder(ctx, name, hostLookupFilesDNS)
 }
 
-func goLookupHostOrder(name string, order hostLookupOrder) (addrs []string, err error) {
+func goLookupHostOrder(ctx context.Context, name string, order hostLookupOrder) (addrs []string, err error) {
 	if order == hostLookupFilesDNS || order == hostLookupFiles {
 		// Use entries from /etc/hosts if they match.
 		addrs = lookupStaticHost(name)
@@ -404,7 +429,7 @@ func goLookupHostOrder(name string, order hostLookupOrder) (addrs []string, err
 			return
 		}
 	}
-	ips, err := goLookupIPOrder(name, order)
+	ips, err := goLookupIPOrder(ctx, name, order)
 	if err != nil {
 		return
 	}
@@ -430,11 +455,11 @@ func goLookupIPFiles(name string) (addrs []IPAddr) {
 
 // goLookupIP is the native Go implementation of LookupIP.
 // The libc versions are in cgo_*.go.
-func goLookupIP(name string) (addrs []IPAddr, err error) {
-	return goLookupIPOrder(name, hostLookupFilesDNS)
+func goLookupIP(ctx context.Context, name string) (addrs []IPAddr, err error) {
+	return goLookupIPOrder(ctx, name, hostLookupFilesDNS)
 }
 
-func goLookupIPOrder(name string, order hostLookupOrder) (addrs []IPAddr, err error) {
+func goLookupIPOrder(ctx context.Context, name string, order hostLookupOrder) (addrs []IPAddr, err error) {
 	if order == hostLookupFilesDNS || order == hostLookupFiles {
 		addrs = goLookupIPFiles(name)
 		if len(addrs) > 0 || order == hostLookupFiles {
@@ -459,7 +484,7 @@ func goLookupIPOrder(name string, order hostLookupOrder) (addrs []IPAddr, err er
 	for _, fqdn := range conf.nameList(name) {
 		for _, qtype := range qtypes {
 			go func(qtype uint16) {
-				_, rrs, err := tryOneName(conf, fqdn, qtype)
+				_, rrs, err := tryOneName(ctx, conf, fqdn, qtype)
 				lane <- racer{fqdn, rrs, err}
 			}(qtype)
 		}
@@ -502,8 +527,8 @@ func goLookupIPOrder(name string, order hostLookupOrder) (addrs []IPAddr, err er
 // Normally we let cgo use the C library resolver instead of
 // depending on our lookup code, so that Go and C get the same
 // answers.
-func goLookupCNAME(name string) (cname string, err error) {
-	_, rrs, err := lookup(name, dnsTypeCNAME)
+func goLookupCNAME(ctx context.Context, name string) (cname string, err error) {
+	_, rrs, err := lookup(ctx, name, dnsTypeCNAME)
 	if err != nil {
 		return
 	}
@@ -516,7 +541,7 @@ func goLookupCNAME(name string) (cname string, err error) {
 // only if cgoLookupPTR is the stub in cgo_stub.go).
 // Normally we let cgo use the C library resolver instead of depending
 // on our lookup code, so that Go and C get the same answers.
-func goLookupPTR(addr string) ([]string, error) {
+func goLookupPTR(ctx context.Context, addr string) ([]string, error) {
 	names := lookupStaticAddr(addr)
 	if len(names) > 0 {
 		return names, nil
@@ -525,7 +550,7 @@ func goLookupPTR(addr string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	_, rrs, err := lookup(arpa, dnsTypePTR)
+	_, rrs, err := lookup(ctx, arpa, dnsTypePTR)
 	if err != nil {
 		return nil, err
 	}
diff --git a/libgo/go/net/dnsclient_unix_test.go b/libgo/go/net/dnsclient_unix_test.go
index 934f25b2c94..09bbd488660 100644
--- a/libgo/go/net/dnsclient_unix_test.go
+++ b/libgo/go/net/dnsclient_unix_test.go
@@ -7,7 +7,9 @@
 package net
 
 import (
+	"context"
 	"fmt"
+	"internal/testenv"
 	"io/ioutil"
 	"os"
 	"path"
@@ -18,6 +20,9 @@ import (
 	"time"
 )
 
+// Test address from 192.0.2.0/24 block, reserved by RFC 5737 for documentation.
+const TestAddr uint32 = 0xc0000201
+
 var dnsTransportFallbackTests = []struct {
 	server  string
 	name    string
@@ -32,13 +37,12 @@ var dnsTransportFallbackTests = []struct {
 }
 
 func TestDNSTransportFallback(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	for _, tt := range dnsTransportFallbackTests {
-		timeout := time.Duration(tt.timeout) * time.Second
-		msg, err := exchange(tt.server, tt.name, tt.qtype, timeout)
+		ctx, cancel := context.WithTimeout(context.Background(), time.Duration(tt.timeout)*time.Second)
+		defer cancel()
+		msg, err := exchange(ctx, tt.server, tt.name, tt.qtype)
 		if err != nil {
 			t.Error(err)
 			continue
@@ -67,20 +71,20 @@ var specialDomainNameTests = []struct {
 
 	// Name resolution APIs and libraries should recognize the
 	// followings as special and should not send any queries.
-	// Though, we test those names here for verifying nagative
+	// Though, we test those names here for verifying negative
 	// answers at DNS query-response interaction level.
 	{"localhost.", dnsTypeALL, dnsRcodeNameError},
 	{"invalid.", dnsTypeALL, dnsRcodeNameError},
 }
 
 func TestSpecialDomainName(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	server := "8.8.8.8:53"
 	for _, tt := range specialDomainNameTests {
-		msg, err := exchange(server, tt.name, tt.qtype, 3*time.Second)
+		ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+		defer cancel()
+		msg, err := exchange(ctx, server, tt.name, tt.qtype)
 		if err != nil {
 			t.Error(err)
 			continue
@@ -94,6 +98,57 @@ func TestSpecialDomainName(t *testing.T) {
 	}
 }
 
+// Issue 13705: don't try to resolve onion addresses, etc
+func TestAvoidDNSName(t *testing.T) {
+	tests := []struct {
+		name  string
+		avoid bool
+	}{
+		{"foo.com", false},
+		{"foo.com.", false},
+
+		{"foo.onion.", true},
+		{"foo.onion", true},
+		{"foo.ONION", true},
+		{"foo.ONION.", true},
+
+		{"foo.local.", true},
+		{"foo.local", true},
+		{"foo.LOCAL", true},
+		{"foo.LOCAL.", true},
+
+		{"", true}, // will be rejected earlier too
+
+		// Without stuff before onion/local, they're fine to
+		// use DNS. With a search path,
+		// "onion.vegegtables.com" can use DNS. Without a
+		// search path (or with a trailing dot), the queries
+		// are just kinda useless, but don't reveal anything
+		// private.
+		{"local", false},
+		{"onion", false},
+		{"local.", false},
+		{"onion.", false},
+	}
+	for _, tt := range tests {
+		got := avoidDNS(tt.name)
+		if got != tt.avoid {
+			t.Errorf("avoidDNS(%q) = %v; want %v", tt.name, got, tt.avoid)
+		}
+	}
+}
+
+// Issue 13705: don't try to resolve onion addresses, etc
+func TestLookupTorOnion(t *testing.T) {
+	addrs, err := goLookupIP(context.Background(), "foo.onion")
+	if len(addrs) > 0 {
+		t.Errorf("unexpected addresses: %v", addrs)
+	}
+	if err != nil {
+		t.Fatalf("lookup = %v; want nil", err)
+	}
+}
+
 type resolvConfTest struct {
 	dir  string
 	path string
@@ -124,20 +179,20 @@ func (conf *resolvConfTest) writeAndUpdate(lines []string) error {
 		return err
 	}
 	f.Close()
-	if err := conf.forceUpdate(conf.path); err != nil {
+	if err := conf.forceUpdate(conf.path, time.Now().Add(time.Hour)); err != nil {
 		return err
 	}
 	return nil
 }
 
-func (conf *resolvConfTest) forceUpdate(name string) error {
+func (conf *resolvConfTest) forceUpdate(name string, lastChecked time.Time) error {
 	dnsConf := dnsReadConfig(name)
 	conf.mu.Lock()
 	conf.dnsConfig = dnsConf
 	conf.mu.Unlock()
 	for i := 0; i < 5; i++ {
 		if conf.tryAcquireSema() {
-			conf.lastChecked = time.Time{}
+			conf.lastChecked = lastChecked
 			conf.releaseSema()
 			return nil
 		}
@@ -153,7 +208,7 @@ func (conf *resolvConfTest) servers() []string {
 }
 
 func (conf *resolvConfTest) teardown() error {
-	err := conf.forceUpdate("/etc/resolv.conf")
+	err := conf.forceUpdate("/etc/resolv.conf", time.Time{})
 	os.RemoveAll(conf.dir)
 	return err
 }
@@ -166,7 +221,7 @@ var updateResolvConfTests = []struct {
 	{
 		name:    "golang.org",
 		lines:   []string{"nameserver 8.8.8.8"},
-		servers: []string{"8.8.8.8"},
+		servers: []string{"8.8.8.8:53"},
 	},
 	{
 		name:    "",
@@ -176,14 +231,12 @@ var updateResolvConfTests = []struct {
 	{
 		name:    "www.example.com",
 		lines:   []string{"nameserver 8.8.4.4"},
-		servers: []string{"8.8.4.4"},
+		servers: []string{"8.8.4.4:53"},
 	},
 }
 
 func TestUpdateResolvConf(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	conf, err := newResolvConfTest()
 	if err != nil {
@@ -203,7 +256,7 @@ func TestUpdateResolvConf(t *testing.T) {
 			for j := 0; j < N; j++ {
 				go func(name string) {
 					defer wg.Done()
-					ips, err := goLookupIP(name)
+					ips, err := goLookupIP(context.Background(), name)
 					if err != nil {
 						t.Error(err)
 						return
@@ -338,9 +391,7 @@ var goLookupIPWithResolverConfigTests = []struct {
 }
 
 func TestGoLookupIPWithResolverConfig(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	conf, err := newResolvConfTest()
 	if err != nil {
@@ -353,10 +404,15 @@ func TestGoLookupIPWithResolverConfig(t *testing.T) {
 			t.Error(err)
 			continue
 		}
-		conf.tryUpdate(conf.path)
-		addrs, err := goLookupIP(tt.name)
+		addrs, err := goLookupIP(context.Background(), tt.name)
 		if err != nil {
-			if err, ok := err.(*DNSError); !ok || (err.Name != tt.error.(*DNSError).Name || err.Server != tt.error.(*DNSError).Server || err.IsTimeout != tt.error.(*DNSError).IsTimeout) {
+			// This test uses external network connectivity.
+			// We need to take care with errors on both
+			// DNS message exchange layer and DNS
+			// transport layer because goLookupIP may fail
+			// when the IP connectivty on node under test
+			// gets lost during its run.
+			if err, ok := err.(*DNSError); !ok || tt.error != nil && (err.Name != tt.error.(*DNSError).Name || err.Server != tt.error.(*DNSError).Server || err.IsTimeout != tt.error.(*DNSError).IsTimeout) {
 				t.Errorf("got %v; want %v", err, tt.error)
 			}
 			continue
@@ -380,9 +436,7 @@ func TestGoLookupIPWithResolverConfig(t *testing.T) {
 
 // Test that goLookupIPOrder falls back to the host file when no DNS servers are available.
 func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	// Add a config that simulates no dns servers being available.
 	conf, err := newResolvConfTest()
@@ -392,7 +446,6 @@ func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
 	if err := conf.writeAndUpdate([]string{}); err != nil {
 		t.Fatal(err)
 	}
-	conf.tryUpdate(conf.path)
 	// Redirect host file lookups.
 	defer func(orig string) { testHookHostsPath = orig }(testHookHostsPath)
 	testHookHostsPath = "testdata/hosts"
@@ -400,15 +453,15 @@ func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
 	for _, order := range []hostLookupOrder{hostLookupFilesDNS, hostLookupDNSFiles} {
 		name := fmt.Sprintf("order %v", order)
 
-		// First ensure that we get an error when contacting a non-existant host.
-		_, err := goLookupIPOrder("notarealhost", order)
+		// First ensure that we get an error when contacting a non-existent host.
+		_, err := goLookupIPOrder(context.Background(), "notarealhost", order)
 		if err == nil {
 			t.Errorf("%s: expected error while looking up name not in hosts file", name)
 			continue
 		}
 
 		// Now check that we get an address when the name appears in the hosts file.
-		addrs, err := goLookupIPOrder("thor", order) // entry is in "testdata/hosts"
+		addrs, err := goLookupIPOrder(context.Background(), "thor", order) // entry is in "testdata/hosts"
 		if err != nil {
 			t.Errorf("%s: expected to successfully lookup host entry", name)
 			continue
@@ -444,10 +497,10 @@ func TestErrorForOriginalNameWhenSearching(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	d := &fakeDNSConn{}
-	testHookDNSDialer = func(time.Duration) dnsDialer { return d }
+	d := &fakeDNSDialer{}
+	testHookDNSDialer = func() dnsDialer { return d }
 
-	d.rh = func(q *dnsMsg) (*dnsMsg, error) {
+	d.rh = func(s string, q *dnsMsg) (*dnsMsg, error) {
 		r := &dnsMsg{
 			dnsMsgHdr: dnsMsgHdr{
 				id: q.id,
@@ -464,7 +517,7 @@ func TestErrorForOriginalNameWhenSearching(t *testing.T) {
 		return r, nil
 	}
 
-	_, err = goLookupIP(fqdn)
+	_, err = goLookupIP(context.Background(), fqdn)
 	if err == nil {
 		t.Fatal("expected an error")
 	}
@@ -475,19 +528,83 @@ func TestErrorForOriginalNameWhenSearching(t *testing.T) {
 	}
 }
 
+// Issue 15434. If a name server gives a lame referral, continue to the next.
+func TestIgnoreLameReferrals(t *testing.T) {
+	origTestHookDNSDialer := testHookDNSDialer
+	defer func() { testHookDNSDialer = origTestHookDNSDialer }()
+
+	conf, err := newResolvConfTest()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conf.teardown()
+
+	if err := conf.writeAndUpdate([]string{"nameserver 192.0.2.1", "nameserver 192.0.2.2"}); err != nil {
+		t.Fatal(err)
+	}
+
+	d := &fakeDNSDialer{}
+	testHookDNSDialer = func() dnsDialer { return d }
+
+	d.rh = func(s string, q *dnsMsg) (*dnsMsg, error) {
+		t.Log(s, q)
+		r := &dnsMsg{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       q.id,
+				response: true,
+			},
+			question: q.question,
+		}
+
+		if s == "192.0.2.2:53" {
+			r.recursion_available = true
+			if q.question[0].Qtype == dnsTypeA {
+				r.answer = []dnsRR{
+					&dnsRR_A{
+						Hdr: dnsRR_Header{
+							Name:     q.question[0].Name,
+							Rrtype:   dnsTypeA,
+							Class:    dnsClassINET,
+							Rdlength: 4,
+						},
+						A: TestAddr,
+					},
+				}
+			}
+		}
+
+		return r, nil
+	}
+
+	addrs, err := goLookupIP(context.Background(), "www.golang.org")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if got := len(addrs); got != 1 {
+		t.Fatalf("got %d addresses, want 1", got)
+	}
+
+	if got, want := addrs[0].String(), "192.0.2.1"; got != want {
+		t.Fatalf("got address %v, want %v", got, want)
+	}
+}
+
 func BenchmarkGoLookupIP(b *testing.B) {
 	testHookUninstaller.Do(uninstallTestHooks)
+	ctx := context.Background()
 
 	for i := 0; i < b.N; i++ {
-		goLookupIP("www.example.com")
+		goLookupIP(ctx, "www.example.com")
 	}
 }
 
 func BenchmarkGoLookupIPNoSuchHost(b *testing.B) {
 	testHookUninstaller.Do(uninstallTestHooks)
+	ctx := context.Background()
 
 	for i := 0; i < b.N; i++ {
-		goLookupIP("some.nonexistent")
+		goLookupIP(ctx, "some.nonexistent")
 	}
 }
 
@@ -507,22 +624,25 @@ func BenchmarkGoLookupIPWithBrokenNameServer(b *testing.B) {
 	if err := conf.writeAndUpdate(lines); err != nil {
 		b.Fatal(err)
 	}
+	ctx := context.Background()
 
 	for i := 0; i < b.N; i++ {
-		goLookupIP("www.example.com")
+		goLookupIP(ctx, "www.example.com")
 	}
 }
 
-type fakeDNSConn struct {
-	// last query
-	qmu sync.Mutex // guards q
-	q   *dnsMsg
+type fakeDNSDialer struct {
 	// reply handler
-	rh func(*dnsMsg) (*dnsMsg, error)
+	rh func(s string, q *dnsMsg) (*dnsMsg, error)
 }
 
-func (f *fakeDNSConn) dialDNS(n, s string) (dnsConn, error) {
-	return f, nil
+func (f *fakeDNSDialer) dialDNS(_ context.Context, n, s string) (dnsConn, error) {
+	return &fakeDNSConn{f.rh, s}, nil
+}
+
+type fakeDNSConn struct {
+	rh func(s string, q *dnsMsg) (*dnsMsg, error)
+	s  string
 }
 
 func (f *fakeDNSConn) Close() error {
@@ -533,16 +653,74 @@ func (f *fakeDNSConn) SetDeadline(time.Time) error {
 	return nil
 }
 
-func (f *fakeDNSConn) writeDNSQuery(q *dnsMsg) error {
-	f.qmu.Lock()
-	defer f.qmu.Unlock()
-	f.q = q
-	return nil
+func (f *fakeDNSConn) dnsRoundTrip(q *dnsMsg) (*dnsMsg, error) {
+	return f.rh(f.s, q)
 }
 
-func (f *fakeDNSConn) readDNSResponse() (*dnsMsg, error) {
-	f.qmu.Lock()
-	q := f.q
-	f.qmu.Unlock()
-	return f.rh(q)
+// UDP round-tripper algorithm should ignore invalid DNS responses (issue 13281).
+func TestIgnoreDNSForgeries(t *testing.T) {
+	c, s := Pipe()
+	go func() {
+		b := make([]byte, 512)
+		n, err := s.Read(b)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		msg := &dnsMsg{}
+		if !msg.Unpack(b[:n]) {
+			t.Fatal("invalid DNS query")
+		}
+
+		s.Write([]byte("garbage DNS response packet"))
+
+		msg.response = true
+		msg.id++ // make invalid ID
+		b, ok := msg.Pack()
+		if !ok {
+			t.Fatal("failed to pack DNS response")
+		}
+		s.Write(b)
+
+		msg.id-- // restore original ID
+		msg.answer = []dnsRR{
+			&dnsRR_A{
+				Hdr: dnsRR_Header{
+					Name:     "www.example.com.",
+					Rrtype:   dnsTypeA,
+					Class:    dnsClassINET,
+					Rdlength: 4,
+				},
+				A: TestAddr,
+			},
+		}
+
+		b, ok = msg.Pack()
+		if !ok {
+			t.Fatal("failed to pack DNS response")
+		}
+		s.Write(b)
+	}()
+
+	msg := &dnsMsg{
+		dnsMsgHdr: dnsMsgHdr{
+			id: 42,
+		},
+		question: []dnsQuestion{
+			{
+				Name:   "www.example.com.",
+				Qtype:  dnsTypeA,
+				Qclass: dnsClassINET,
+			},
+		},
+	}
+
+	resp, err := dnsRoundTripUDP(c, msg)
+	if err != nil {
+		t.Fatalf("dnsRoundTripUDP failed: %v", err)
+	}
+
+	if got := resp.answer[0].(*dnsRR_A).A; got != TestAddr {
+		t.Errorf("got address %v, want %v", got, TestAddr)
+	}
 }
diff --git a/libgo/go/net/dnsconfig_unix.go b/libgo/go/net/dnsconfig_unix.go
index 6073fdb6d83..aec575e8541 100644
--- a/libgo/go/net/dnsconfig_unix.go
+++ b/libgo/go/net/dnsconfig_unix.go
@@ -8,36 +8,52 @@
 
 package net
 
-var defaultNS = []string{"127.0.0.1", "::1"}
+import (
+	"os"
+	"time"
+)
+
+var (
+	defaultNS   = []string{"127.0.0.1:53", "[::1]:53"}
+	getHostname = os.Hostname // variable for testing
+)
 
 type dnsConfig struct {
-	servers    []string // servers to use
-	search     []string // suffixes to append to local name
-	ndots      int      // number of dots in name to trigger absolute lookup
-	timeout    int      // seconds before giving up on packet
-	attempts   int      // lost packets before giving up on server
-	rotate     bool     // round robin among servers
-	unknownOpt bool     // anything unknown was encountered
-	lookup     []string // OpenBSD top-level database "lookup" order
-	err        error    // any error that occurs during open of resolv.conf
+	servers    []string      // server addresses (in host:port form) to use
+	search     []string      // rooted suffixes to append to local name
+	ndots      int           // number of dots in name to trigger absolute lookup
+	timeout    time.Duration // wait before giving up on a query, including retries
+	attempts   int           // lost packets before giving up on server
+	rotate     bool          // round robin among servers
+	unknownOpt bool          // anything unknown was encountered
+	lookup     []string      // OpenBSD top-level database "lookup" order
+	err        error         // any error that occurs during open of resolv.conf
+	mtime      time.Time     // time of resolv.conf modification
 }
 
 // See resolv.conf(5) on a Linux machine.
-// TODO(rsc): Supposed to call uname() and chop the beginning
-// of the host name to get the default search domain.
 func dnsReadConfig(filename string) *dnsConfig {
 	conf := &dnsConfig{
 		ndots:    1,
-		timeout:  5,
+		timeout:  5 * time.Second,
 		attempts: 2,
 	}
 	file, err := open(filename)
 	if err != nil {
 		conf.servers = defaultNS
+		conf.search = dnsDefaultSearch()
 		conf.err = err
 		return conf
 	}
 	defer file.close()
+	if fi, err := file.file.Stat(); err == nil {
+		conf.mtime = fi.ModTime()
+	} else {
+		conf.servers = defaultNS
+		conf.search = dnsDefaultSearch()
+		conf.err = err
+		return conf
+	}
 	for line, ok := file.readLine(); ok; line, ok = file.readLine() {
 		if len(line) > 0 && (line[0] == ';' || line[0] == '#') {
 			// comment.
@@ -51,24 +67,24 @@ func dnsReadConfig(filename string) *dnsConfig {
 		case "nameserver": // add one name server
 			if len(f) > 1 && len(conf.servers) < 3 { // small, but the standard limit
 				// One more check: make sure server name is
-				// just an IP address.  Otherwise we need DNS
+				// just an IP address. Otherwise we need DNS
 				// to look it up.
 				if parseIPv4(f[1]) != nil {
-					conf.servers = append(conf.servers, f[1])
+					conf.servers = append(conf.servers, JoinHostPort(f[1], "53"))
 				} else if ip, _ := parseIPv6(f[1], true); ip != nil {
-					conf.servers = append(conf.servers, f[1])
+					conf.servers = append(conf.servers, JoinHostPort(f[1], "53"))
 				}
 			}
 
 		case "domain": // set search path to just this domain
 			if len(f) > 1 {
-				conf.search = []string{f[1]}
+				conf.search = []string{ensureRooted(f[1])}
 			}
 
 		case "search": // set search path to given servers
 			conf.search = make([]string, len(f)-1)
 			for i := 0; i < len(conf.search); i++ {
-				conf.search[i] = f[i+1]
+				conf.search[i] = ensureRooted(f[i+1])
 			}
 
 		case "options": // magic options
@@ -85,7 +101,7 @@ func dnsReadConfig(filename string) *dnsConfig {
 					if n < 1 {
 						n = 1
 					}
-					conf.timeout = n
+					conf.timeout = time.Duration(n) * time.Second
 				case hasPrefix(s, "attempts:"):
 					n, _, _ := dtoi(s, 9)
 					if n < 1 {
@@ -112,9 +128,31 @@ func dnsReadConfig(filename string) *dnsConfig {
 	if len(conf.servers) == 0 {
 		conf.servers = defaultNS
 	}
+	if len(conf.search) == 0 {
+		conf.search = dnsDefaultSearch()
+	}
 	return conf
 }
 
+func dnsDefaultSearch() []string {
+	hn, err := getHostname()
+	if err != nil {
+		// best effort
+		return nil
+	}
+	if i := byteIndex(hn, '.'); i >= 0 && i < len(hn)-1 {
+		return []string{ensureRooted(hn[i+1:])}
+	}
+	return nil
+}
+
 func hasPrefix(s, prefix string) bool {
 	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
 }
+
+func ensureRooted(s string) string {
+	if len(s) > 0 && s[len(s)-1] == '.' {
+		return s
+	}
+	return s + "."
+}
diff --git a/libgo/go/net/dnsconfig_unix_test.go b/libgo/go/net/dnsconfig_unix_test.go
index c8eed618904..9fd6dbf982a 100644
--- a/libgo/go/net/dnsconfig_unix_test.go
+++ b/libgo/go/net/dnsconfig_unix_test.go
@@ -7,9 +7,11 @@
 package net
 
 import (
+	"errors"
 	"os"
 	"reflect"
 	"testing"
+	"time"
 )
 
 var dnsReadConfigTests = []struct {
@@ -19,10 +21,10 @@ var dnsReadConfigTests = []struct {
 	{
 		name: "testdata/resolv.conf",
 		want: &dnsConfig{
-			servers:    []string{"8.8.8.8", "2001:4860:4860::8888", "fe80::1%lo0"},
-			search:     []string{"localdomain"},
+			servers:    []string{"8.8.8.8:53", "[2001:4860:4860::8888]:53", "[fe80::1%lo0]:53"},
+			search:     []string{"localdomain."},
 			ndots:      5,
-			timeout:    10,
+			timeout:    10 * time.Second,
 			attempts:   3,
 			rotate:     true,
 			unknownOpt: true, // the "options attempts 3" line
@@ -31,20 +33,20 @@ var dnsReadConfigTests = []struct {
 	{
 		name: "testdata/domain-resolv.conf",
 		want: &dnsConfig{
-			servers:  []string{"8.8.8.8"},
-			search:   []string{"localdomain"},
+			servers:  []string{"8.8.8.8:53"},
+			search:   []string{"localdomain."},
 			ndots:    1,
-			timeout:  5,
+			timeout:  5 * time.Second,
 			attempts: 2,
 		},
 	},
 	{
 		name: "testdata/search-resolv.conf",
 		want: &dnsConfig{
-			servers:  []string{"8.8.8.8"},
-			search:   []string{"test", "invalid"},
+			servers:  []string{"8.8.8.8:53"},
+			search:   []string{"test.", "invalid."},
 			ndots:    1,
-			timeout:  5,
+			timeout:  5 * time.Second,
 			attempts: 2,
 		},
 	},
@@ -53,29 +55,35 @@ var dnsReadConfigTests = []struct {
 		want: &dnsConfig{
 			servers:  defaultNS,
 			ndots:    1,
-			timeout:  5,
+			timeout:  5 * time.Second,
 			attempts: 2,
+			search:   []string{"domain.local."},
 		},
 	},
 	{
 		name: "testdata/openbsd-resolv.conf",
 		want: &dnsConfig{
 			ndots:    1,
-			timeout:  5,
+			timeout:  5 * time.Second,
 			attempts: 2,
 			lookup:   []string{"file", "bind"},
-			servers:  []string{"169.254.169.254", "10.240.0.1"},
+			servers:  []string{"169.254.169.254:53", "10.240.0.1:53"},
 			search:   []string{"c.symbolic-datum-552.internal."},
 		},
 	},
 }
 
 func TestDNSReadConfig(t *testing.T) {
+	origGetHostname := getHostname
+	defer func() { getHostname = origGetHostname }()
+	getHostname = func() (string, error) { return "host.domain.local", nil }
+
 	for _, tt := range dnsReadConfigTests {
 		conf := dnsReadConfig(tt.name)
 		if conf.err != nil {
 			t.Fatal(conf.err)
 		}
+		conf.mtime = time.Time{}
 		if !reflect.DeepEqual(conf, tt.want) {
 			t.Errorf("%s:\ngot: %+v\nwant: %+v", tt.name, conf, tt.want)
 		}
@@ -83,6 +91,10 @@ func TestDNSReadConfig(t *testing.T) {
 }
 
 func TestDNSReadMissingFile(t *testing.T) {
+	origGetHostname := getHostname
+	defer func() { getHostname = origGetHostname }()
+	getHostname = func() (string, error) { return "host.domain.local", nil }
+
 	conf := dnsReadConfig("a-nonexistent-file")
 	if !os.IsNotExist(conf.err) {
 		t.Errorf("missing resolv.conf:\ngot: %v\nwant: %v", conf.err, os.ErrNotExist)
@@ -91,10 +103,54 @@ func TestDNSReadMissingFile(t *testing.T) {
 	want := &dnsConfig{
 		servers:  defaultNS,
 		ndots:    1,
-		timeout:  5,
+		timeout:  5 * time.Second,
 		attempts: 2,
+		search:   []string{"domain.local."},
 	}
 	if !reflect.DeepEqual(conf, want) {
 		t.Errorf("missing resolv.conf:\ngot: %+v\nwant: %+v", conf, want)
 	}
 }
+
+var dnsDefaultSearchTests = []struct {
+	name string
+	err  error
+	want []string
+}{
+	{
+		name: "host.long.domain.local",
+		want: []string{"long.domain.local."},
+	},
+	{
+		name: "host.local",
+		want: []string{"local."},
+	},
+	{
+		name: "host",
+		want: nil,
+	},
+	{
+		name: "host.domain.local",
+		err:  errors.New("errored"),
+		want: nil,
+	},
+	{
+		// ensures we don't return []string{""}
+		// which causes duplicate lookups
+		name: "foo.",
+		want: nil,
+	},
+}
+
+func TestDNSDefaultSearch(t *testing.T) {
+	origGetHostname := getHostname
+	defer func() { getHostname = origGetHostname }()
+
+	for _, tt := range dnsDefaultSearchTests {
+		getHostname = func() (string, error) { return tt.name, tt.err }
+		got := dnsDefaultSearch()
+		if !reflect.DeepEqual(got, tt.want) {
+			t.Errorf("dnsDefaultSearch with hostname %q and error %+v = %q, wanted %q", tt.name, tt.err, got, tt.want)
+		}
+	}
+}
diff --git a/libgo/go/net/dnsmsg.go b/libgo/go/net/dnsmsg.go
index 93078fe8499..afdb44c0ea5 100644
--- a/libgo/go/net/dnsmsg.go
+++ b/libgo/go/net/dnsmsg.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// DNS packet assembly.  See RFC 1035.
+// DNS packet assembly. See RFC 1035.
 //
 // This is intended to support name resolution during Dial.
 // It doesn't have to be blazing fast.
@@ -18,7 +18,7 @@
 // generic pack/unpack routines.
 //
 // TODO(rsc):  There are enough names defined in this file that they're all
-// prefixed with dns.  Perhaps put this in its own package later.
+// prefixed with dns. Perhaps put this in its own package later.
 
 package net
 
@@ -109,7 +109,7 @@ const (
 
 // DNS queries.
 type dnsQuestion struct {
-	Name   string `net:"domain-name"` // `net:"domain-name"` specifies encoding; see packers below
+	Name   string
 	Qtype  uint16
 	Qclass uint16
 }
@@ -124,7 +124,7 @@ func (q *dnsQuestion) Walk(f func(v interface{}, name, tag string) bool) bool {
 // There are many types of messages,
 // but they all share the same header.
 type dnsRR_Header struct {
-	Name     string `net:"domain-name"`
+	Name     string
 	Rrtype   uint16
 	Class    uint16
 	Ttl      uint32
@@ -152,7 +152,7 @@ type dnsRR interface {
 
 type dnsRR_CNAME struct {
 	Hdr   dnsRR_Header
-	Cname string `net:"domain-name"`
+	Cname string
 }
 
 func (rr *dnsRR_CNAME) Header() *dnsRR_Header {
@@ -163,77 +163,10 @@ func (rr *dnsRR_CNAME) Walk(f func(v interface{}, name, tag string) bool) bool {
 	return rr.Hdr.Walk(f) && f(&rr.Cname, "Cname", "domain")
 }
 
-type dnsRR_HINFO struct {
-	Hdr dnsRR_Header
-	Cpu string
-	Os  string
-}
-
-func (rr *dnsRR_HINFO) Header() *dnsRR_Header {
-	return &rr.Hdr
-}
-
-func (rr *dnsRR_HINFO) Walk(f func(v interface{}, name, tag string) bool) bool {
-	return rr.Hdr.Walk(f) && f(&rr.Cpu, "Cpu", "") && f(&rr.Os, "Os", "")
-}
-
-type dnsRR_MB struct {
-	Hdr dnsRR_Header
-	Mb  string `net:"domain-name"`
-}
-
-func (rr *dnsRR_MB) Header() *dnsRR_Header {
-	return &rr.Hdr
-}
-
-func (rr *dnsRR_MB) Walk(f func(v interface{}, name, tag string) bool) bool {
-	return rr.Hdr.Walk(f) && f(&rr.Mb, "Mb", "domain")
-}
-
-type dnsRR_MG struct {
-	Hdr dnsRR_Header
-	Mg  string `net:"domain-name"`
-}
-
-func (rr *dnsRR_MG) Header() *dnsRR_Header {
-	return &rr.Hdr
-}
-
-func (rr *dnsRR_MG) Walk(f func(v interface{}, name, tag string) bool) bool {
-	return rr.Hdr.Walk(f) && f(&rr.Mg, "Mg", "domain")
-}
-
-type dnsRR_MINFO struct {
-	Hdr   dnsRR_Header
-	Rmail string `net:"domain-name"`
-	Email string `net:"domain-name"`
-}
-
-func (rr *dnsRR_MINFO) Header() *dnsRR_Header {
-	return &rr.Hdr
-}
-
-func (rr *dnsRR_MINFO) Walk(f func(v interface{}, name, tag string) bool) bool {
-	return rr.Hdr.Walk(f) && f(&rr.Rmail, "Rmail", "domain") && f(&rr.Email, "Email", "domain")
-}
-
-type dnsRR_MR struct {
-	Hdr dnsRR_Header
-	Mr  string `net:"domain-name"`
-}
-
-func (rr *dnsRR_MR) Header() *dnsRR_Header {
-	return &rr.Hdr
-}
-
-func (rr *dnsRR_MR) Walk(f func(v interface{}, name, tag string) bool) bool {
-	return rr.Hdr.Walk(f) && f(&rr.Mr, "Mr", "domain")
-}
-
 type dnsRR_MX struct {
 	Hdr  dnsRR_Header
 	Pref uint16
-	Mx   string `net:"domain-name"`
+	Mx   string
 }
 
 func (rr *dnsRR_MX) Header() *dnsRR_Header {
@@ -246,7 +179,7 @@ func (rr *dnsRR_MX) Walk(f func(v interface{}, name, tag string) bool) bool {
 
 type dnsRR_NS struct {
 	Hdr dnsRR_Header
-	Ns  string `net:"domain-name"`
+	Ns  string
 }
 
 func (rr *dnsRR_NS) Header() *dnsRR_Header {
@@ -259,7 +192,7 @@ func (rr *dnsRR_NS) Walk(f func(v interface{}, name, tag string) bool) bool {
 
 type dnsRR_PTR struct {
 	Hdr dnsRR_Header
-	Ptr string `net:"domain-name"`
+	Ptr string
 }
 
 func (rr *dnsRR_PTR) Header() *dnsRR_Header {
@@ -272,8 +205,8 @@ func (rr *dnsRR_PTR) Walk(f func(v interface{}, name, tag string) bool) bool {
 
 type dnsRR_SOA struct {
 	Hdr     dnsRR_Header
-	Ns      string `net:"domain-name"`
-	Mbox    string `net:"domain-name"`
+	Ns      string
+	Mbox    string
 	Serial  uint32
 	Refresh uint32
 	Retry   uint32
@@ -315,7 +248,7 @@ func (rr *dnsRR_TXT) Walk(f func(v interface{}, name, tag string) bool) bool {
 		if !f(&txt, "Txt", "") {
 			return false
 		}
-		// more bytes than rr.Hdr.Rdlength said there woudld be
+		// more bytes than rr.Hdr.Rdlength said there would be
 		if rr.Hdr.Rdlength-n < uint16(len(txt))+1 {
 			return false
 		}
@@ -330,7 +263,7 @@ type dnsRR_SRV struct {
 	Priority uint16
 	Weight   uint16
 	Port     uint16
-	Target   string `net:"domain-name"`
+	Target   string
 }
 
 func (rr *dnsRR_SRV) Header() *dnsRR_Header {
@@ -347,7 +280,7 @@ func (rr *dnsRR_SRV) Walk(f func(v interface{}, name, tag string) bool) bool {
 
 type dnsRR_A struct {
 	Hdr dnsRR_Header
-	A   uint32 `net:"ipv4"`
+	A   uint32
 }
 
 func (rr *dnsRR_A) Header() *dnsRR_Header {
@@ -360,7 +293,7 @@ func (rr *dnsRR_A) Walk(f func(v interface{}, name, tag string) bool) bool {
 
 type dnsRR_AAAA struct {
 	Hdr  dnsRR_Header
-	AAAA [16]byte `net:"ipv6"`
+	AAAA [16]byte
 }
 
 func (rr *dnsRR_AAAA) Header() *dnsRR_Header {
@@ -376,17 +309,12 @@ func (rr *dnsRR_AAAA) Walk(f func(v interface{}, name, tag string) bool) bool {
 // All the packers and unpackers take a (msg []byte, off int)
 // and return (off1 int, ok bool).  If they return ok==false, they
 // also return off1==len(msg), so that the next unpacker will
-// also fail.  This lets us avoid checks of ok until the end of a
+// also fail. This lets us avoid checks of ok until the end of a
 // packing sequence.
 
 // Map of constructors for each RR wire type.
 var rr_mk = map[int]func() dnsRR{
 	dnsTypeCNAME: func() dnsRR { return new(dnsRR_CNAME) },
-	dnsTypeHINFO: func() dnsRR { return new(dnsRR_HINFO) },
-	dnsTypeMB:    func() dnsRR { return new(dnsRR_MB) },
-	dnsTypeMG:    func() dnsRR { return new(dnsRR_MG) },
-	dnsTypeMINFO: func() dnsRR { return new(dnsRR_MINFO) },
-	dnsTypeMR:    func() dnsRR { return new(dnsRR_MR) },
 	dnsTypeMX:    func() dnsRR { return new(dnsRR_MX) },
 	dnsTypeNS:    func() dnsRR { return new(dnsRR_NS) },
 	dnsTypePTR:   func() dnsRR { return new(dnsRR_PTR) },
@@ -399,13 +327,20 @@ var rr_mk = map[int]func() dnsRR{
 
 // Pack a domain name s into msg[off:].
 // Domain names are a sequence of counted strings
-// split at the dots.  They end with a zero-length string.
+// split at the dots. They end with a zero-length string.
 func packDomainName(s string, msg []byte, off int) (off1 int, ok bool) {
 	// Add trailing dot to canonicalize name.
 	if n := len(s); n == 0 || s[n-1] != '.' {
 		s += "."
 	}
 
+	// Allow root domain.
+	if s == "." {
+		msg[off] = 0
+		off++
+		return off, true
+	}
+
 	// Each dot ends a segment of the name.
 	// We trade each dot byte for a length byte.
 	// There is also a trailing zero.
@@ -422,8 +357,13 @@ func packDomainName(s string, msg []byte, off int) (off1 int, ok bool) {
 			if i-begin >= 1<<6 { // top two bits of length must be clear
 				return len(msg), false
 			}
+			if i-begin == 0 {
+				return len(msg), false
+			}
+
 			msg[off] = byte(i - begin)
 			off++
+
 			for j := begin; j < i; j++ {
 				msg[off] = s[j]
 				off++
@@ -440,8 +380,8 @@ func packDomainName(s string, msg []byte, off int) (off1 int, ok bool) {
 // In addition to the simple sequences of counted strings above,
 // domain names are allowed to refer to strings elsewhere in the
 // packet, to avoid repeating common suffixes when returning
-// many entries in a single domain.  The pointers are marked
-// by a length byte with the top two bits set.  Ignoring those
+// many entries in a single domain. The pointers are marked
+// by a length byte with the top two bits set. Ignoring those
 // two bits, that byte and the next give a 14 bit offset from msg[0]
 // where we should pick up the trail.
 // Note that if we jump elsewhere in the packet,
@@ -494,6 +434,9 @@ Loop:
 			return "", len(msg), false
 		}
 	}
+	if len(s) == 0 {
+		s = "."
+	}
 	if ptr == 0 {
 		off1 = off
 	}
@@ -803,20 +746,32 @@ func (dns *dnsMsg) Pack() (msg []byte, ok bool) {
 	// Pack it in: header and then the pieces.
 	off := 0
 	off, ok = packStruct(&dh, msg, off)
+	if !ok {
+		return nil, false
+	}
 	for i := 0; i < len(question); i++ {
 		off, ok = packStruct(&question[i], msg, off)
+		if !ok {
+			return nil, false
+		}
 	}
 	for i := 0; i < len(answer); i++ {
 		off, ok = packRR(answer[i], msg, off)
+		if !ok {
+			return nil, false
+		}
 	}
 	for i := 0; i < len(ns); i++ {
 		off, ok = packRR(ns[i], msg, off)
+		if !ok {
+			return nil, false
+		}
 	}
 	for i := 0; i < len(extra); i++ {
 		off, ok = packRR(extra[i], msg, off)
-	}
-	if !ok {
-		return nil, false
+		if !ok {
+			return nil, false
+		}
 	}
 	return msg[0:off], true
 }
@@ -848,6 +803,9 @@ func (dns *dnsMsg) Unpack(msg []byte) bool {
 
 	for i := 0; i < len(dns.question); i++ {
 		off, ok = unpackStruct(&dns.question[i], msg, off)
+		if !ok {
+			return false
+		}
 	}
 	for i := 0; i < int(dh.Ancount); i++ {
 		rec, off, ok = unpackRR(msg, off)
@@ -904,3 +862,23 @@ func (dns *dnsMsg) String() string {
 	}
 	return s
 }
+
+// IsResponseTo reports whether m is an acceptable response to query.
+func (m *dnsMsg) IsResponseTo(query *dnsMsg) bool {
+	if !m.response {
+		return false
+	}
+	if m.id != query.id {
+		return false
+	}
+	if len(m.question) != len(query.question) {
+		return false
+	}
+	for i, q := range m.question {
+		q2 := query.question[i]
+		if !equalASCIILabel(q.Name, q2.Name) || q.Qtype != q2.Qtype || q.Qclass != q2.Qclass {
+			return false
+		}
+	}
+	return true
+}
diff --git a/libgo/go/net/dnsmsg_test.go b/libgo/go/net/dnsmsg_test.go
index 1078d77ceb9..25bd98cff76 100644
--- a/libgo/go/net/dnsmsg_test.go
+++ b/libgo/go/net/dnsmsg_test.go
@@ -10,6 +10,103 @@ import (
 	"testing"
 )
 
+func TestStructPackUnpack(t *testing.T) {
+	want := dnsQuestion{
+		Name:   ".",
+		Qtype:  dnsTypeA,
+		Qclass: dnsClassINET,
+	}
+	buf := make([]byte, 50)
+	n, ok := packStruct(&want, buf, 0)
+	if !ok {
+		t.Fatal("packing failed")
+	}
+	buf = buf[:n]
+	got := dnsQuestion{}
+	n, ok = unpackStruct(&got, buf, 0)
+	if !ok {
+		t.Fatal("unpacking failed")
+	}
+	if n != len(buf) {
+		t.Errorf("unpacked different amount than packed: got n = %d, want = %d", n, len(buf))
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("got = %+v, want = %+v", got, want)
+	}
+}
+
+func TestDomainNamePackUnpack(t *testing.T) {
+	tests := []struct {
+		in   string
+		want string
+		ok   bool
+	}{
+		{"", ".", true},
+		{".", ".", true},
+		{"google..com", "", false},
+		{"google.com", "google.com.", true},
+		{"google..com.", "", false},
+		{"google.com.", "google.com.", true},
+		{".google.com.", "", false},
+		{"www..google.com.", "", false},
+		{"www.google.com.", "www.google.com.", true},
+	}
+
+	for _, test := range tests {
+		buf := make([]byte, 30)
+		n, ok := packDomainName(test.in, buf, 0)
+		if ok != test.ok {
+			t.Errorf("packing of %s: got ok = %t, want = %t", test.in, ok, test.ok)
+			continue
+		}
+		if !test.ok {
+			continue
+		}
+		buf = buf[:n]
+		got, n, ok := unpackDomainName(buf, 0)
+		if !ok {
+			t.Errorf("unpacking for %s failed", test.in)
+			continue
+		}
+		if n != len(buf) {
+			t.Errorf(
+				"unpacked different amount than packed for %s: got n = %d, want = %d",
+				test.in,
+				n,
+				len(buf),
+			)
+		}
+		if got != test.want {
+			t.Errorf("unpacking packing of %s: got = %s, want = %s", test.in, got, test.want)
+		}
+	}
+}
+
+func TestDNSPackUnpack(t *testing.T) {
+	want := dnsMsg{
+		question: []dnsQuestion{{
+			Name:   ".",
+			Qtype:  dnsTypeAAAA,
+			Qclass: dnsClassINET,
+		}},
+		answer: []dnsRR{},
+		ns:     []dnsRR{},
+		extra:  []dnsRR{},
+	}
+	b, ok := want.Pack()
+	if !ok {
+		t.Fatal("packing failed")
+	}
+	var got dnsMsg
+	ok = got.Unpack(b)
+	if !ok {
+		t.Fatal("unpacking failed")
+	}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("got = %+v, want = %+v", got, want)
+	}
+}
+
 func TestDNSParseSRVReply(t *testing.T) {
 	data, err := hex.DecodeString(dnsSRVReply)
 	if err != nil {
@@ -183,6 +280,124 @@ func TestDNSParseTXTCorruptTXTLengthReply(t *testing.T) {
 	}
 }
 
+func TestIsResponseTo(t *testing.T) {
+	// Sample DNS query.
+	query := dnsMsg{
+		dnsMsgHdr: dnsMsgHdr{
+			id: 42,
+		},
+		question: []dnsQuestion{
+			{
+				Name:   "www.example.com.",
+				Qtype:  dnsTypeA,
+				Qclass: dnsClassINET,
+			},
+		},
+	}
+
+	resp := query
+	resp.response = true
+	if !resp.IsResponseTo(&query) {
+		t.Error("got false, want true")
+	}
+
+	badResponses := []dnsMsg{
+		// Different ID.
+		{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       43,
+				response: true,
+			},
+			question: []dnsQuestion{
+				{
+					Name:   "www.example.com.",
+					Qtype:  dnsTypeA,
+					Qclass: dnsClassINET,
+				},
+			},
+		},
+
+		// Different query name.
+		{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       42,
+				response: true,
+			},
+			question: []dnsQuestion{
+				{
+					Name:   "www.google.com.",
+					Qtype:  dnsTypeA,
+					Qclass: dnsClassINET,
+				},
+			},
+		},
+
+		// Different query type.
+		{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       42,
+				response: true,
+			},
+			question: []dnsQuestion{
+				{
+					Name:   "www.example.com.",
+					Qtype:  dnsTypeAAAA,
+					Qclass: dnsClassINET,
+				},
+			},
+		},
+
+		// Different query class.
+		{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       42,
+				response: true,
+			},
+			question: []dnsQuestion{
+				{
+					Name:   "www.example.com.",
+					Qtype:  dnsTypeA,
+					Qclass: dnsClassCSNET,
+				},
+			},
+		},
+
+		// No questions.
+		{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       42,
+				response: true,
+			},
+		},
+
+		// Extra questions.
+		{
+			dnsMsgHdr: dnsMsgHdr{
+				id:       42,
+				response: true,
+			},
+			question: []dnsQuestion{
+				{
+					Name:   "www.example.com.",
+					Qtype:  dnsTypeA,
+					Qclass: dnsClassINET,
+				},
+				{
+					Name:   "www.golang.org.",
+					Qtype:  dnsTypeAAAA,
+					Qclass: dnsClassINET,
+				},
+			},
+		},
+	}
+
+	for i := range badResponses {
+		if badResponses[i].IsResponseTo(&query) {
+			t.Error("%v: got true, want false", i)
+		}
+	}
+}
+
 // Valid DNS SRV reply
 const dnsSRVReply = "0901818000010005000000000c5f786d70702d736572766572045f74637006676f6f67" +
 	"6c6503636f6d0000210001c00c002100010000012c00210014000014950c786d70702d" +
diff --git a/libgo/go/net/dnsname_test.go b/libgo/go/net/dnsname_test.go
index be07dc6a16f..bc777b855e1 100644
--- a/libgo/go/net/dnsname_test.go
+++ b/libgo/go/net/dnsname_test.go
@@ -15,7 +15,7 @@ type dnsNameTest struct {
 }
 
 var dnsNameTests = []dnsNameTest{
-	// RFC2181, section 11.
+	// RFC 2181, section 11.
 	{"_xmpp-server._tcp.google.com", true},
 	{"foo.com", true},
 	{"1foo.com", true},
diff --git a/libgo/go/net/error_plan9_test.go b/libgo/go/net/error_plan9_test.go
index 495ea965343..d7c7f1487fb 100644
--- a/libgo/go/net/error_plan9_test.go
+++ b/libgo/go/net/error_plan9_test.go
@@ -9,6 +9,8 @@ import "syscall"
 var (
 	errTimedout       = syscall.ETIMEDOUT
 	errOpNotSupported = syscall.EPLAN9
+
+	abortedConnRequestErrors []error
 )
 
 func isPlatformError(err error) bool {
diff --git a/libgo/go/net/error_posix_test.go b/libgo/go/net/error_posix_test.go
index 981cc837ba4..b411a378dfc 100644
--- a/libgo/go/net/error_posix_test.go
+++ b/libgo/go/net/error_posix_test.go
@@ -12,16 +12,6 @@ import (
 	"testing"
 )
 
-var (
-	errTimedout       = syscall.ETIMEDOUT
-	errOpNotSupported = syscall.EOPNOTSUPP
-)
-
-func isPlatformError(err error) bool {
-	_, ok := err.(syscall.Errno)
-	return ok
-}
-
 func TestSpuriousENOTAVAIL(t *testing.T) {
 	for _, tt := range []struct {
 		error
diff --git a/libgo/go/net/error_test.go b/libgo/go/net/error_test.go
index 1aab14c4499..d6de5a3e68f 100644
--- a/libgo/go/net/error_test.go
+++ b/libgo/go/net/error_test.go
@@ -5,6 +5,7 @@
 package net
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -91,9 +92,12 @@ second:
 	case *os.SyscallError:
 		nestedErr = err.Err
 		goto third
+	case *os.PathError: // for Plan 9
+		nestedErr = err.Err
+		goto third
 	}
 	switch nestedErr {
-	case errCanceled, errClosing, errMissingAddress:
+	case errCanceled, errClosing, errMissingAddress, errNoSuitableAddress:
 		return nil
 	}
 	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)
@@ -135,7 +139,7 @@ func TestDialError(t *testing.T) {
 
 	origTestHookLookupIP := testHookLookupIP
 	defer func() { testHookLookupIP = origTestHookLookupIP }()
-	testHookLookupIP = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+	testHookLookupIP = func(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
 		return nil, &DNSError{Err: "dial error test", Name: "name", Server: "server", IsTimeout: true}
 	}
 	sw.Set(socktest.FilterConnect, func(so *socktest.Status) (socktest.AfterFilter, error) {
@@ -203,6 +207,58 @@ func TestProtocolDialError(t *testing.T) {
 	}
 }
 
+func TestDialAddrError(t *testing.T) {
+	switch runtime.GOOS {
+	case "nacl", "plan9":
+		t.Skipf("not supported on %s", runtime.GOOS)
+	}
+	if !supportsIPv4 || !supportsIPv6 {
+		t.Skip("both IPv4 and IPv6 are required")
+	}
+
+	for _, tt := range []struct {
+		network string
+		lit     string
+		addr    *TCPAddr
+	}{
+		{"tcp4", "::1", nil},
+		{"tcp4", "", &TCPAddr{IP: IPv6loopback}},
+		// We don't test the {"tcp6", "byte sequence", nil}
+		// case for now because there is no easy way to
+		// control name resolution.
+		{"tcp6", "", &TCPAddr{IP: IP{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef}}},
+	} {
+		var err error
+		var c Conn
+		if tt.lit != "" {
+			c, err = Dial(tt.network, JoinHostPort(tt.lit, "0"))
+		} else {
+			c, err = DialTCP(tt.network, nil, tt.addr)
+		}
+		if err == nil {
+			c.Close()
+			t.Errorf("%s %q/%v: should fail", tt.network, tt.lit, tt.addr)
+			continue
+		}
+		if perr := parseDialError(err); perr != nil {
+			t.Error(perr)
+			continue
+		}
+		aerr, ok := err.(*OpError).Err.(*AddrError)
+		if !ok {
+			t.Errorf("%s %q/%v: should be AddrError: %v", tt.network, tt.lit, tt.addr, err)
+			continue
+		}
+		want := tt.lit
+		if tt.lit == "" {
+			want = tt.addr.IP.String()
+		}
+		if aerr.Addr != want {
+			t.Fatalf("%s: got %q; want %q", tt.network, aerr.Addr, want)
+		}
+	}
+}
+
 var listenErrorTests = []struct {
 	network, address string
 }{
@@ -228,7 +284,7 @@ func TestListenError(t *testing.T) {
 
 	origTestHookLookupIP := testHookLookupIP
 	defer func() { testHookLookupIP = origTestHookLookupIP }()
-	testHookLookupIP = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+	testHookLookupIP = func(_ context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
 		return nil, &DNSError{Err: "listen error test", Name: "name", Server: "server", IsTimeout: true}
 	}
 	sw.Set(socktest.FilterListen, func(so *socktest.Status) (socktest.AfterFilter, error) {
@@ -288,7 +344,7 @@ func TestListenPacketError(t *testing.T) {
 
 	origTestHookLookupIP := testHookLookupIP
 	defer func() { testHookLookupIP = origTestHookLookupIP }()
-	testHookLookupIP = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+	testHookLookupIP = func(_ context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
 		return nil, &DNSError{Err: "listen error test", Name: "name", Server: "server", IsTimeout: true}
 	}
 
@@ -413,7 +469,7 @@ second:
 		goto third
 	}
 	switch nestedErr {
-	case errCanceled, errClosing, errTimeout, ErrWriteToConnected, io.ErrUnexpectedEOF:
+	case errCanceled, errClosing, errMissingAddress, errTimeout, ErrWriteToConnected, io.ErrUnexpectedEOF:
 		return nil
 	}
 	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)
@@ -543,6 +599,9 @@ second:
 	case *os.SyscallError:
 		nestedErr = err.Err
 		goto third
+	case *os.PathError: // for Plan 9
+		nestedErr = err.Err
+		goto third
 	}
 	switch nestedErr {
 	case errClosing, errTimeout:
@@ -703,3 +762,17 @@ func TestFileError(t *testing.T) {
 		ln.Close()
 	}
 }
+
+func parseLookupPortError(nestedErr error) error {
+	if nestedErr == nil {
+		return nil
+	}
+
+	switch nestedErr.(type) {
+	case *AddrError, *DNSError:
+		return nil
+	case *os.PathError: // for Plan 9
+		return nil
+	}
+	return fmt.Errorf("unexpected type on 1st nested level: %T", nestedErr)
+}
diff --git a/libgo/go/net/error_unix_test.go b/libgo/go/net/error_unix_test.go
new file mode 100644
index 00000000000..9ce9e12c5ec
--- /dev/null
+++ b/libgo/go/net/error_unix_test.go
@@ -0,0 +1,34 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9,!windows
+
+package net
+
+import (
+	"os"
+	"syscall"
+)
+
+var (
+	errTimedout       = syscall.ETIMEDOUT
+	errOpNotSupported = syscall.EOPNOTSUPP
+
+	abortedConnRequestErrors = []error{syscall.ECONNABORTED} // see accept in fd_unix.go
+)
+
+func isPlatformError(err error) bool {
+	_, ok := err.(syscall.Errno)
+	return ok
+}
+
+func samePlatformError(err, want error) bool {
+	if op, ok := err.(*OpError); ok {
+		err = op.Err
+	}
+	if sys, ok := err.(*os.SyscallError); ok {
+		err = sys.Err
+	}
+	return err == want
+}
diff --git a/libgo/go/net/error_windows_test.go b/libgo/go/net/error_windows_test.go
new file mode 100644
index 00000000000..834a9de4411
--- /dev/null
+++ b/libgo/go/net/error_windows_test.go
@@ -0,0 +1,19 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import "syscall"
+
+var (
+	errTimedout       = syscall.ETIMEDOUT
+	errOpNotSupported = syscall.EOPNOTSUPP
+
+	abortedConnRequestErrors = []error{syscall.ERROR_NETNAME_DELETED, syscall.WSAECONNRESET} // see accept in fd_windows.go
+)
+
+func isPlatformError(err error) bool {
+	_, ok := err.(syscall.Errno)
+	return ok
+}
diff --git a/libgo/go/net/external_test.go b/libgo/go/net/external_test.go
index d5ff2be20a3..e18b547cac9 100644
--- a/libgo/go/net/external_test.go
+++ b/libgo/go/net/external_test.go
@@ -6,15 +6,15 @@ package net
 
 import (
 	"fmt"
+	"internal/testenv"
 	"io"
 	"strings"
 	"testing"
 )
 
 func TestResolveGoogle(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
+
 	if !supportsIPv4 || !supportsIPv6 || !*testIPv4 || !*testIPv6 {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
@@ -60,9 +60,8 @@ var dialGoogleTests = []struct {
 }
 
 func TestDialGoogle(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
+
 	if !supportsIPv4 || !supportsIPv6 || !*testIPv4 || !*testIPv6 {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
diff --git a/libgo/go/net/fd_mutex.go b/libgo/go/net/fd_mutex.go
index 6d5509d7f2a..4591fd1cac8 100644
--- a/libgo/go/net/fd_mutex.go
+++ b/libgo/go/net/fd_mutex.go
@@ -6,9 +6,9 @@ package net
 
 import "sync/atomic"
 
-// fdMutex is a specialized synchronization primitive
-// that manages lifetime of an fd and serializes access
-// to Read and Write methods on netFD.
+// fdMutex is a specialized synchronization primitive that manages
+// lifetime of an fd and serializes access to Read, Write and Close
+// methods on netFD.
 type fdMutex struct {
 	state uint64
 	rsema uint32
@@ -34,18 +34,21 @@ const (
 	mutexWMask   = (1<<20 - 1) << 43
 )
 
-// Read operations must do RWLock(true)/RWUnlock(true).
-// Write operations must do RWLock(false)/RWUnlock(false).
-// Misc operations must do Incref/Decref. Misc operations include functions like
-// setsockopt and setDeadline. They need to use Incref/Decref to ensure that
-// they operate on the correct fd in presence of a concurrent Close call
-// (otherwise fd can be closed under their feet).
-// Close operation must do IncrefAndClose/Decref.
+// Read operations must do rwlock(true)/rwunlock(true).
+//
+// Write operations must do rwlock(false)/rwunlock(false).
+//
+// Misc operations must do incref/decref.
+// Misc operations include functions like setsockopt and setDeadline.
+// They need to use incref/decref to ensure that they operate on the
+// correct fd in presence of a concurrent close call (otherwise fd can
+// be closed under their feet).
+//
+// Close operations must do increfAndClose/decref.
 
-// RWLock/Incref return whether fd is open.
-// RWUnlock/Decref return whether fd is closed and there are no remaining references.
-
-func (mu *fdMutex) Incref() bool {
+// incref adds a reference to mu.
+// It reports whether mu is available for reading or writing.
+func (mu *fdMutex) incref() bool {
 	for {
 		old := atomic.LoadUint64(&mu.state)
 		if old&mutexClosed != 0 {
@@ -61,7 +64,9 @@ func (mu *fdMutex) Incref() bool {
 	}
 }
 
-func (mu *fdMutex) IncrefAndClose() bool {
+// increfAndClose sets the state of mu to closed.
+// It reports whether there is no remaining reference.
+func (mu *fdMutex) increfAndClose() bool {
 	for {
 		old := atomic.LoadUint64(&mu.state)
 		if old&mutexClosed != 0 {
@@ -90,7 +95,9 @@ func (mu *fdMutex) IncrefAndClose() bool {
 	}
 }
 
-func (mu *fdMutex) Decref() bool {
+// decref removes a reference from mu.
+// It reports whether there is no remaining reference.
+func (mu *fdMutex) decref() bool {
 	for {
 		old := atomic.LoadUint64(&mu.state)
 		if old&mutexRefMask == 0 {
@@ -103,7 +110,9 @@ func (mu *fdMutex) Decref() bool {
 	}
 }
 
-func (mu *fdMutex) RWLock(read bool) bool {
+// lock adds a reference to mu and locks mu.
+// It reports whether mu is available for reading or writing.
+func (mu *fdMutex) rwlock(read bool) bool {
 	var mutexBit, mutexWait, mutexMask uint64
 	var mutexSema *uint32
 	if read {
@@ -146,7 +155,9 @@ func (mu *fdMutex) RWLock(read bool) bool {
 	}
 }
 
-func (mu *fdMutex) RWUnlock(read bool) bool {
+// unlock removes a reference from mu and unlocks mu.
+// It reports whether there is no remaining reference.
+func (mu *fdMutex) rwunlock(read bool) bool {
 	var mutexBit, mutexWait, mutexMask uint64
 	var mutexSema *uint32
 	if read {
@@ -182,3 +193,57 @@ func (mu *fdMutex) RWUnlock(read bool) bool {
 // Implemented in runtime package.
 func runtime_Semacquire(sema *uint32)
 func runtime_Semrelease(sema *uint32)
+
+// incref adds a reference to fd.
+// It returns an error when fd cannot be used.
+func (fd *netFD) incref() error {
+	if !fd.fdmu.incref() {
+		return errClosing
+	}
+	return nil
+}
+
+// decref removes a reference from fd.
+// It also closes fd when the state of fd is set to closed and there
+// is no remaining reference.
+func (fd *netFD) decref() {
+	if fd.fdmu.decref() {
+		fd.destroy()
+	}
+}
+
+// readLock adds a reference to fd and locks fd for reading.
+// It returns an error when fd cannot be used for reading.
+func (fd *netFD) readLock() error {
+	if !fd.fdmu.rwlock(true) {
+		return errClosing
+	}
+	return nil
+}
+
+// readUnlock removes a reference from fd and unlocks fd for reading.
+// It also closes fd when the state of fd is set to closed and there
+// is no remaining reference.
+func (fd *netFD) readUnlock() {
+	if fd.fdmu.rwunlock(true) {
+		fd.destroy()
+	}
+}
+
+// writeLock adds a reference to fd and locks fd for writing.
+// It returns an error when fd cannot be used for writing.
+func (fd *netFD) writeLock() error {
+	if !fd.fdmu.rwlock(false) {
+		return errClosing
+	}
+	return nil
+}
+
+// writeUnlock removes a reference from fd and unlocks fd for writing.
+// It also closes fd when the state of fd is set to closed and there
+// is no remaining reference.
+func (fd *netFD) writeUnlock() {
+	if fd.fdmu.rwunlock(false) {
+		fd.destroy()
+	}
+}
diff --git a/libgo/go/net/fd_mutex_test.go b/libgo/go/net/fd_mutex_test.go
index c34ec59b996..3542c70f9d1 100644
--- a/libgo/go/net/fd_mutex_test.go
+++ b/libgo/go/net/fd_mutex_test.go
@@ -14,44 +14,44 @@ import (
 func TestMutexLock(t *testing.T) {
 	var mu fdMutex
 
-	if !mu.Incref() {
+	if !mu.incref() {
 		t.Fatal("broken")
 	}
-	if mu.Decref() {
+	if mu.decref() {
 		t.Fatal("broken")
 	}
 
-	if !mu.RWLock(true) {
+	if !mu.rwlock(true) {
 		t.Fatal("broken")
 	}
-	if mu.RWUnlock(true) {
+	if mu.rwunlock(true) {
 		t.Fatal("broken")
 	}
 
-	if !mu.RWLock(false) {
+	if !mu.rwlock(false) {
 		t.Fatal("broken")
 	}
-	if mu.RWUnlock(false) {
+	if mu.rwunlock(false) {
 		t.Fatal("broken")
 	}
 }
 
 func TestMutexClose(t *testing.T) {
 	var mu fdMutex
-	if !mu.IncrefAndClose() {
+	if !mu.increfAndClose() {
 		t.Fatal("broken")
 	}
 
-	if mu.Incref() {
+	if mu.incref() {
 		t.Fatal("broken")
 	}
-	if mu.RWLock(true) {
+	if mu.rwlock(true) {
 		t.Fatal("broken")
 	}
-	if mu.RWLock(false) {
+	if mu.rwlock(false) {
 		t.Fatal("broken")
 	}
-	if mu.IncrefAndClose() {
+	if mu.increfAndClose() {
 		t.Fatal("broken")
 	}
 }
@@ -59,10 +59,10 @@ func TestMutexClose(t *testing.T) {
 func TestMutexCloseUnblock(t *testing.T) {
 	c := make(chan bool)
 	var mu fdMutex
-	mu.RWLock(true)
+	mu.rwlock(true)
 	for i := 0; i < 4; i++ {
 		go func() {
-			if mu.RWLock(true) {
+			if mu.rwlock(true) {
 				t.Error("broken")
 				return
 			}
@@ -76,7 +76,7 @@ func TestMutexCloseUnblock(t *testing.T) {
 		t.Fatal("broken")
 	default:
 	}
-	mu.IncrefAndClose() // Must unblock the readers.
+	mu.increfAndClose() // Must unblock the readers.
 	for i := 0; i < 4; i++ {
 		select {
 		case <-c:
@@ -84,10 +84,10 @@ func TestMutexCloseUnblock(t *testing.T) {
 			t.Fatal("broken")
 		}
 	}
-	if mu.Decref() {
+	if mu.decref() {
 		t.Fatal("broken")
 	}
-	if !mu.RWUnlock(true) {
+	if !mu.rwunlock(true) {
 		t.Fatal("broken")
 	}
 }
@@ -103,21 +103,21 @@ func TestMutexPanic(t *testing.T) {
 	}
 
 	var mu fdMutex
-	ensurePanics(func() { mu.Decref() })
-	ensurePanics(func() { mu.RWUnlock(true) })
-	ensurePanics(func() { mu.RWUnlock(false) })
+	ensurePanics(func() { mu.decref() })
+	ensurePanics(func() { mu.rwunlock(true) })
+	ensurePanics(func() { mu.rwunlock(false) })
 
-	ensurePanics(func() { mu.Incref(); mu.Decref(); mu.Decref() })
-	ensurePanics(func() { mu.RWLock(true); mu.RWUnlock(true); mu.RWUnlock(true) })
-	ensurePanics(func() { mu.RWLock(false); mu.RWUnlock(false); mu.RWUnlock(false) })
+	ensurePanics(func() { mu.incref(); mu.decref(); mu.decref() })
+	ensurePanics(func() { mu.rwlock(true); mu.rwunlock(true); mu.rwunlock(true) })
+	ensurePanics(func() { mu.rwlock(false); mu.rwunlock(false); mu.rwunlock(false) })
 
 	// ensure that it's still not broken
-	mu.Incref()
-	mu.Decref()
-	mu.RWLock(true)
-	mu.RWUnlock(true)
-	mu.RWLock(false)
-	mu.RWUnlock(false)
+	mu.incref()
+	mu.decref()
+	mu.rwlock(true)
+	mu.rwunlock(true)
+	mu.rwlock(false)
+	mu.rwunlock(false)
 }
 
 func TestMutexStress(t *testing.T) {
@@ -138,16 +138,16 @@ func TestMutexStress(t *testing.T) {
 			for i := 0; i < N; i++ {
 				switch r.Intn(3) {
 				case 0:
-					if !mu.Incref() {
+					if !mu.incref() {
 						t.Error("broken")
 						return
 					}
-					if mu.Decref() {
+					if mu.decref() {
 						t.Error("broken")
 						return
 					}
 				case 1:
-					if !mu.RWLock(true) {
+					if !mu.rwlock(true) {
 						t.Error("broken")
 						return
 					}
@@ -158,12 +158,12 @@ func TestMutexStress(t *testing.T) {
 					}
 					readState[0]++
 					readState[1]++
-					if mu.RWUnlock(true) {
+					if mu.rwunlock(true) {
 						t.Error("broken")
 						return
 					}
 				case 2:
-					if !mu.RWLock(false) {
+					if !mu.rwlock(false) {
 						t.Error("broken")
 						return
 					}
@@ -174,7 +174,7 @@ func TestMutexStress(t *testing.T) {
 					}
 					writeState[0]++
 					writeState[1]++
-					if mu.RWUnlock(false) {
+					if mu.rwunlock(false) {
 						t.Error("broken")
 						return
 					}
@@ -186,10 +186,10 @@ func TestMutexStress(t *testing.T) {
 	for p := 0; p < P; p++ {
 		<-done
 	}
-	if !mu.IncrefAndClose() {
+	if !mu.increfAndClose() {
 		t.Fatal("broken")
 	}
-	if !mu.Decref() {
+	if !mu.decref() {
 		t.Fatal("broken")
 	}
 }
diff --git a/libgo/go/net/fd_plan9.go b/libgo/go/net/fd_plan9.go
index cec88609d06..7533232dc9b 100644
--- a/libgo/go/net/fd_plan9.go
+++ b/libgo/go/net/fd_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -32,12 +32,6 @@ func sysInit() {
 	netdir = "/net"
 }
 
-func dial(net string, ra Addr, dialer func(time.Time) (Conn, error), deadline time.Time) (Conn, error) {
-	// On plan9, use the relatively inefficient
-	// goroutine-racing implementation.
-	return dialChannel(net, ra, dialer, deadline)
-}
-
 func newFD(net, name string, ctl, data *os.File, laddr, raddr Addr) (*netFD, error) {
 	return &netFD{net: net, n: name, dir: netdir + "/" + net + "/" + name, ctl: ctl, data: data, laddr: laddr, raddr: raddr}, nil
 }
@@ -74,55 +68,6 @@ func (fd *netFD) destroy() {
 	fd.data = nil
 }
 
-// Add a reference to this fd.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) incref() error {
-	if !fd.fdmu.Incref() {
-		return errClosing
-	}
-	return nil
-}
-
-// Remove a reference to this FD and close if we've been asked to do so
-// (and there are no references left).
-func (fd *netFD) decref() {
-	if fd.fdmu.Decref() {
-		fd.destroy()
-	}
-}
-
-// Add a reference to this fd and lock for reading.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) readLock() error {
-	if !fd.fdmu.RWLock(true) {
-		return errClosing
-	}
-	return nil
-}
-
-// Unlock for reading and remove a reference to this FD.
-func (fd *netFD) readUnlock() {
-	if fd.fdmu.RWUnlock(true) {
-		fd.destroy()
-	}
-}
-
-// Add a reference to this fd and lock for writing.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) writeLock() error {
-	if !fd.fdmu.RWLock(false) {
-		return errClosing
-	}
-	return nil
-}
-
-// Unlock for writing and remove a reference to this FD.
-func (fd *netFD) writeUnlock() {
-	if fd.fdmu.RWUnlock(false) {
-		fd.destroy()
-	}
-}
-
 func (fd *netFD) Read(b []byte) (n int, err error) {
 	if !fd.ok() || fd.data == nil {
 		return 0, syscall.EINVAL
@@ -131,7 +76,13 @@ func (fd *netFD) Read(b []byte) (n int, err error) {
 		return 0, err
 	}
 	defer fd.readUnlock()
+	if len(b) == 0 {
+		return 0, nil
+	}
 	n, err = fd.data.Read(b)
+	if isHangup(err) {
+		err = io.EOF
+	}
 	if fd.net == "udp" && err == io.EOF {
 		n = 0
 		err = nil
@@ -165,7 +116,7 @@ func (fd *netFD) closeWrite() error {
 }
 
 func (fd *netFD) Close() error {
-	if !fd.fdmu.IncrefAndClose() {
+	if !fd.fdmu.increfAndClose() {
 		return errClosing
 	}
 	if !fd.ok() {
@@ -206,9 +157,7 @@ func (l *TCPListener) dup() (*os.File, error) {
 }
 
 func (fd *netFD) file(f *os.File, s string) (*os.File, error) {
-	syscall.ForkLock.RLock()
 	dfd, err := syscall.Dup(int(f.Fd()), -1)
-	syscall.ForkLock.RUnlock()
 	if err != nil {
 		return nil, os.NewSyscallError("dup", err)
 	}
@@ -234,3 +183,7 @@ func setReadBuffer(fd *netFD, bytes int) error {
 func setWriteBuffer(fd *netFD, bytes int) error {
 	return syscall.EPLAN9
 }
+
+func isHangup(err error) bool {
+	return err != nil && stringsHasSuffix(err.Error(), "Hangup")
+}
diff --git a/libgo/go/net/fd_poll_nacl.go b/libgo/go/net/fd_poll_nacl.go
index cdf14e32ce8..cda8b82c131 100644
--- a/libgo/go/net/fd_poll_nacl.go
+++ b/libgo/go/net/fd_poll_nacl.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -14,44 +14,44 @@ type pollDesc struct {
 	closing bool
 }
 
-func (pd *pollDesc) Init(fd *netFD) error { pd.fd = fd; return nil }
+func (pd *pollDesc) init(fd *netFD) error { pd.fd = fd; return nil }
 
-func (pd *pollDesc) Close() {}
+func (pd *pollDesc) close() {}
 
-func (pd *pollDesc) Evict() {
+func (pd *pollDesc) evict() {
 	pd.closing = true
 	if pd.fd != nil {
 		syscall.StopIO(pd.fd.sysfd)
 	}
 }
 
-func (pd *pollDesc) Prepare(mode int) error {
+func (pd *pollDesc) prepare(mode int) error {
 	if pd.closing {
 		return errClosing
 	}
 	return nil
 }
 
-func (pd *pollDesc) PrepareRead() error { return pd.Prepare('r') }
+func (pd *pollDesc) prepareRead() error { return pd.prepare('r') }
 
-func (pd *pollDesc) PrepareWrite() error { return pd.Prepare('w') }
+func (pd *pollDesc) prepareWrite() error { return pd.prepare('w') }
 
-func (pd *pollDesc) Wait(mode int) error {
+func (pd *pollDesc) wait(mode int) error {
 	if pd.closing {
 		return errClosing
 	}
 	return errTimeout
 }
 
-func (pd *pollDesc) WaitRead() error { return pd.Wait('r') }
+func (pd *pollDesc) waitRead() error { return pd.wait('r') }
 
-func (pd *pollDesc) WaitWrite() error { return pd.Wait('w') }
+func (pd *pollDesc) waitWrite() error { return pd.wait('w') }
 
-func (pd *pollDesc) WaitCanceled(mode int) {}
+func (pd *pollDesc) waitCanceled(mode int) {}
 
-func (pd *pollDesc) WaitCanceledRead() {}
+func (pd *pollDesc) waitCanceledRead() {}
 
-func (pd *pollDesc) WaitCanceledWrite() {}
+func (pd *pollDesc) waitCanceledWrite() {}
 
 func (fd *netFD) setDeadline(t time.Time) error {
 	return setDeadlineImpl(fd, t, 'r'+'w')
diff --git a/libgo/go/net/fd_poll_runtime.go b/libgo/go/net/fd_poll_runtime.go
index 8522ccebfb3..6c1d095bd7f 100644
--- a/libgo/go/net/fd_poll_runtime.go
+++ b/libgo/go/net/fd_poll_runtime.go
@@ -30,7 +30,7 @@ type pollDesc struct {
 
 var serverInit sync.Once
 
-func (pd *pollDesc) Init(fd *netFD) error {
+func (pd *pollDesc) init(fd *netFD) error {
 	serverInit.Do(runtime_pollServerInit)
 	ctx, errno := runtime_pollOpen(uintptr(fd.sysfd))
 	if errno != 0 {
@@ -40,7 +40,7 @@ func (pd *pollDesc) Init(fd *netFD) error {
 	return nil
 }
 
-func (pd *pollDesc) Close() {
+func (pd *pollDesc) close() {
 	if pd.runtimeCtx == 0 {
 		return
 	}
@@ -49,49 +49,49 @@ func (pd *pollDesc) Close() {
 }
 
 // Evict evicts fd from the pending list, unblocking any I/O running on fd.
-func (pd *pollDesc) Evict() {
+func (pd *pollDesc) evict() {
 	if pd.runtimeCtx == 0 {
 		return
 	}
 	runtime_pollUnblock(pd.runtimeCtx)
 }
 
-func (pd *pollDesc) Prepare(mode int) error {
+func (pd *pollDesc) prepare(mode int) error {
 	res := runtime_pollReset(pd.runtimeCtx, mode)
 	return convertErr(res)
 }
 
-func (pd *pollDesc) PrepareRead() error {
-	return pd.Prepare('r')
+func (pd *pollDesc) prepareRead() error {
+	return pd.prepare('r')
 }
 
-func (pd *pollDesc) PrepareWrite() error {
-	return pd.Prepare('w')
+func (pd *pollDesc) prepareWrite() error {
+	return pd.prepare('w')
 }
 
-func (pd *pollDesc) Wait(mode int) error {
+func (pd *pollDesc) wait(mode int) error {
 	res := runtime_pollWait(pd.runtimeCtx, mode)
 	return convertErr(res)
 }
 
-func (pd *pollDesc) WaitRead() error {
-	return pd.Wait('r')
+func (pd *pollDesc) waitRead() error {
+	return pd.wait('r')
 }
 
-func (pd *pollDesc) WaitWrite() error {
-	return pd.Wait('w')
+func (pd *pollDesc) waitWrite() error {
+	return pd.wait('w')
 }
 
-func (pd *pollDesc) WaitCanceled(mode int) {
+func (pd *pollDesc) waitCanceled(mode int) {
 	runtime_pollWaitCanceled(pd.runtimeCtx, mode)
 }
 
-func (pd *pollDesc) WaitCanceledRead() {
-	pd.WaitCanceled('r')
+func (pd *pollDesc) waitCanceledRead() {
+	pd.waitCanceled('r')
 }
 
-func (pd *pollDesc) WaitCanceledWrite() {
-	pd.WaitCanceled('w')
+func (pd *pollDesc) waitCanceledWrite() {
+	pd.waitCanceled('w')
 }
 
 func convertErr(res int) error {
@@ -120,7 +120,13 @@ func (fd *netFD) setWriteDeadline(t time.Time) error {
 }
 
 func setDeadlineImpl(fd *netFD, t time.Time, mode int) error {
-	d := runtimeNano() + int64(t.Sub(time.Now()))
+	diff := int64(t.Sub(time.Now()))
+	d := runtimeNano() + diff
+	if d <= 0 && diff > 0 {
+		// If the user has a deadline in the future, but the delay calculation
+		// overflows, then set the deadline to the maximum possible value.
+		d = 1<<63 - 1
+	}
 	if t.IsZero() {
 		d = 0
 	}
diff --git a/libgo/go/net/fd_unix.go b/libgo/go/net/fd_unix.go
index ff498c2bff0..6fbb9cbf114 100644
--- a/libgo/go/net/fd_unix.go
+++ b/libgo/go/net/fd_unix.go
@@ -7,12 +7,12 @@
 package net
 
 import (
+	"context"
 	"io"
 	"os"
 	"runtime"
 	"sync/atomic"
 	"syscall"
-	"time"
 )
 
 // Network file descriptor.
@@ -36,16 +36,12 @@ type netFD struct {
 func sysInit() {
 }
 
-func dial(network string, ra Addr, dialer func(time.Time) (Conn, error), deadline time.Time) (Conn, error) {
-	return dialer(deadline)
-}
-
 func newFD(sysfd, family, sotype int, net string) (*netFD, error) {
 	return &netFD{sysfd: sysfd, family: family, sotype: sotype, net: net}, nil
 }
 
 func (fd *netFD) init() error {
-	if err := fd.pd.Init(fd); err != nil {
+	if err := fd.pd.init(fd); err != nil {
 		return err
 	}
 	return nil
@@ -68,15 +64,17 @@ func (fd *netFD) name() string {
 	return fd.net + ":" + ls + "->" + rs
 }
 
-func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-chan struct{}) error {
+func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) error {
 	// Do not need to call fd.writeLock here,
 	// because fd is not yet accessible to user,
 	// so no concurrent operations are possible.
 	switch err := connectFunc(fd.sysfd, ra); err {
 	case syscall.EINPROGRESS, syscall.EALREADY, syscall.EINTR:
 	case nil, syscall.EISCONN:
-		if !deadline.IsZero() && deadline.Before(time.Now()) {
-			return errTimeout
+		select {
+		case <-ctx.Done():
+			return mapErr(ctx.Err())
+		default:
 		}
 		if err := fd.init(); err != nil {
 			return err
@@ -98,23 +96,27 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
 	if err := fd.init(); err != nil {
 		return err
 	}
-	if !deadline.IsZero() {
+	if deadline, _ := ctx.Deadline(); !deadline.IsZero() {
 		fd.setWriteDeadline(deadline)
 		defer fd.setWriteDeadline(noDeadline)
 	}
-	if cancel != nil {
-		done := make(chan bool)
-		defer close(done)
-		go func() {
-			select {
-			case <-cancel:
-				// Force the runtime's poller to immediately give
-				// up waiting for writability.
-				fd.setWriteDeadline(aLongTimeAgo)
-			case <-done:
-			}
-		}()
-	}
+
+	// Wait for the goroutine converting context.Done into a write timeout
+	// to exist, otherwise our caller might cancel the context and
+	// cause fd.setWriteDeadline(aLongTimeAgo) to cancel a successful dial.
+	done := make(chan bool) // must be unbuffered
+	defer func() { done <- true }()
+	go func() {
+		select {
+		case <-ctx.Done():
+			// Force the runtime's poller to immediately give
+			// up waiting for writability.
+			fd.setWriteDeadline(aLongTimeAgo)
+			<-done
+		case <-done:
+		}
+	}()
+
 	for {
 		// Performing multiple connect system calls on a
 		// non-blocking socket under Unix variants does not
@@ -124,10 +126,10 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
 		// SO_ERROR socket option to see if the connection
 		// succeeded or failed. See issue 7474 for further
 		// details.
-		if err := fd.pd.WaitWrite(); err != nil {
+		if err := fd.pd.waitWrite(); err != nil {
 			select {
-			case <-cancel:
-				return errCanceled
+			case <-ctx.Done():
+				return mapErr(ctx.Err())
 			default:
 			}
 			return err
@@ -139,7 +141,16 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
 		switch err := syscall.Errno(nerr); err {
 		case syscall.EINPROGRESS, syscall.EALREADY, syscall.EINTR:
 		case syscall.Errno(0), syscall.EISCONN:
-			return nil
+			if runtime.GOOS != "darwin" {
+				return nil
+			}
+			// See golang.org/issue/14548.
+			// On Darwin, multiple connect system calls on
+			// a non-blocking socket never harm SO_ERROR.
+			switch err := connectFunc(fd.sysfd, ra); err {
+			case nil, syscall.EISCONN:
+				return nil
+			}
 		default:
 			return os.NewSyscallError("getsockopt", err)
 		}
@@ -149,71 +160,22 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
 func (fd *netFD) destroy() {
 	// Poller may want to unregister fd in readiness notification mechanism,
 	// so this must be executed before closeFunc.
-	fd.pd.Close()
+	fd.pd.close()
 	closeFunc(fd.sysfd)
 	fd.sysfd = -1
 	runtime.SetFinalizer(fd, nil)
 }
 
-// Add a reference to this fd.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) incref() error {
-	if !fd.fdmu.Incref() {
-		return errClosing
-	}
-	return nil
-}
-
-// Remove a reference to this FD and close if we've been asked to do so
-// (and there are no references left).
-func (fd *netFD) decref() {
-	if fd.fdmu.Decref() {
-		fd.destroy()
-	}
-}
-
-// Add a reference to this fd and lock for reading.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) readLock() error {
-	if !fd.fdmu.RWLock(true) {
-		return errClosing
-	}
-	return nil
-}
-
-// Unlock for reading and remove a reference to this FD.
-func (fd *netFD) readUnlock() {
-	if fd.fdmu.RWUnlock(true) {
-		fd.destroy()
-	}
-}
-
-// Add a reference to this fd and lock for writing.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) writeLock() error {
-	if !fd.fdmu.RWLock(false) {
-		return errClosing
-	}
-	return nil
-}
-
-// Unlock for writing and remove a reference to this FD.
-func (fd *netFD) writeUnlock() {
-	if fd.fdmu.RWUnlock(false) {
-		fd.destroy()
-	}
-}
-
 func (fd *netFD) Close() error {
-	if !fd.fdmu.IncrefAndClose() {
+	if !fd.fdmu.increfAndClose() {
 		return errClosing
 	}
 	// Unblock any I/O.  Once it all unblocks and returns,
 	// so that it cannot be referring to fd.sysfd anymore,
-	// the final decref will close fd.sysfd.  This should happen
+	// the final decref will close fd.sysfd. This should happen
 	// fairly quickly, since all the I/O is non-blocking, and any
 	// attempts to block in the pollDesc will return errClosing.
-	fd.pd.Evict()
+	fd.pd.evict()
 	fd.decref()
 	return nil
 }
@@ -239,7 +201,15 @@ func (fd *netFD) Read(p []byte) (n int, err error) {
 		return 0, err
 	}
 	defer fd.readUnlock()
-	if err := fd.pd.PrepareRead(); err != nil {
+	if len(p) == 0 {
+		// If the caller wanted a zero byte read, return immediately
+		// without trying. (But after acquiring the readLock.) Otherwise
+		// syscall.Read returns 0, nil and eofError turns that into
+		// io.EOF.
+		// TODO(bradfitz): make it wait for readability? (Issue 15735)
+		return 0, nil
+	}
+	if err := fd.pd.prepareRead(); err != nil {
 		return 0, err
 	}
 	for {
@@ -247,7 +217,7 @@ func (fd *netFD) Read(p []byte) (n int, err error) {
 		if err != nil {
 			n = 0
 			if err == syscall.EAGAIN {
-				if err = fd.pd.WaitRead(); err == nil {
+				if err = fd.pd.waitRead(); err == nil {
 					continue
 				}
 			}
@@ -266,7 +236,7 @@ func (fd *netFD) readFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
 		return 0, nil, err
 	}
 	defer fd.readUnlock()
-	if err := fd.pd.PrepareRead(); err != nil {
+	if err := fd.pd.prepareRead(); err != nil {
 		return 0, nil, err
 	}
 	for {
@@ -274,7 +244,7 @@ func (fd *netFD) readFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
 		if err != nil {
 			n = 0
 			if err == syscall.EAGAIN {
-				if err = fd.pd.WaitRead(); err == nil {
+				if err = fd.pd.waitRead(); err == nil {
 					continue
 				}
 			}
@@ -293,7 +263,7 @@ func (fd *netFD) readMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.S
 		return 0, 0, 0, nil, err
 	}
 	defer fd.readUnlock()
-	if err := fd.pd.PrepareRead(); err != nil {
+	if err := fd.pd.prepareRead(); err != nil {
 		return 0, 0, 0, nil, err
 	}
 	for {
@@ -301,7 +271,7 @@ func (fd *netFD) readMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.S
 		if err != nil {
 			// TODO(dfc) should n and oobn be set to 0
 			if err == syscall.EAGAIN {
-				if err = fd.pd.WaitRead(); err == nil {
+				if err = fd.pd.waitRead(); err == nil {
 					continue
 				}
 			}
@@ -320,7 +290,7 @@ func (fd *netFD) Write(p []byte) (nn int, err error) {
 		return 0, err
 	}
 	defer fd.writeUnlock()
-	if err := fd.pd.PrepareWrite(); err != nil {
+	if err := fd.pd.prepareWrite(); err != nil {
 		return 0, err
 	}
 	for {
@@ -333,7 +303,7 @@ func (fd *netFD) Write(p []byte) (nn int, err error) {
 			break
 		}
 		if err == syscall.EAGAIN {
-			if err = fd.pd.WaitWrite(); err == nil {
+			if err = fd.pd.waitWrite(); err == nil {
 				continue
 			}
 		}
@@ -356,13 +326,13 @@ func (fd *netFD) writeTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
 		return 0, err
 	}
 	defer fd.writeUnlock()
-	if err := fd.pd.PrepareWrite(); err != nil {
+	if err := fd.pd.prepareWrite(); err != nil {
 		return 0, err
 	}
 	for {
 		err = syscall.Sendto(fd.sysfd, p, 0, sa)
 		if err == syscall.EAGAIN {
-			if err = fd.pd.WaitWrite(); err == nil {
+			if err = fd.pd.waitWrite(); err == nil {
 				continue
 			}
 		}
@@ -382,13 +352,13 @@ func (fd *netFD) writeMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oob
 		return 0, 0, err
 	}
 	defer fd.writeUnlock()
-	if err := fd.pd.PrepareWrite(); err != nil {
+	if err := fd.pd.prepareWrite(); err != nil {
 		return 0, 0, err
 	}
 	for {
 		n, err = syscall.SendmsgN(fd.sysfd, p, oob, sa, 0)
 		if err == syscall.EAGAIN {
-			if err = fd.pd.WaitWrite(); err == nil {
+			if err = fd.pd.waitWrite(); err == nil {
 				continue
 			}
 		}
@@ -411,7 +381,7 @@ func (fd *netFD) accept() (netfd *netFD, err error) {
 
 	var s int
 	var rsa syscall.Sockaddr
-	if err = fd.pd.PrepareRead(); err != nil {
+	if err = fd.pd.prepareRead(); err != nil {
 		return nil, err
 	}
 	for {
@@ -423,7 +393,7 @@ func (fd *netFD) accept() (netfd *netFD, err error) {
 			}
 			switch nerr.Err {
 			case syscall.EAGAIN:
-				if err = fd.pd.WaitRead(); err == nil {
+				if err = fd.pd.waitRead(); err == nil {
 					continue
 				}
 			case syscall.ECONNABORTED:
@@ -472,7 +442,7 @@ func dupCloseOnExec(fd int) (newfd int, err error) {
 			// and fcntl there falls back (undocumented)
 			// to doing an ioctl instead, returning EBADF
 			// in this case because fd is not of the
-			// expected device fd type.  Treat it as
+			// expected device fd type. Treat it as
 			// EINVAL instead, so we fall back to the
 			// normal dup path.
 			// TODO: only do this on 10.6 if we can detect 10.6
diff --git a/libgo/go/net/fd_windows.go b/libgo/go/net/fd_windows.go
index fd50d772d60..b0b6769eb3c 100644
--- a/libgo/go/net/fd_windows.go
+++ b/libgo/go/net/fd_windows.go
@@ -5,12 +5,12 @@
 package net
 
 import (
+	"context"
 	"internal/race"
 	"os"
 	"runtime"
 	"sync"
 	"syscall"
-	"time"
 	"unsafe"
 )
 
@@ -42,11 +42,6 @@ func sysInit() {
 		initErr = os.NewSyscallError("wsastartup", e)
 	}
 	canCancelIO = syscall.LoadCancelIoEx() == nil
-	if syscall.LoadGetAddrInfo() == nil {
-		lookupPort = newLookupPort
-		lookupIP = newLookupIP
-	}
-
 	hasLoadSetFileCompletionNotificationModes = syscall.LoadSetFileCompletionNotificationModes() == nil
 	if hasLoadSetFileCompletionNotificationModes {
 		// It's not safe to use FILE_SKIP_COMPLETION_PORT_ON_SUCCESS if non IFS providers are installed:
@@ -69,22 +64,15 @@ func sysInit() {
 	}
 }
 
+// canUseConnectEx reports whether we can use the ConnectEx Windows API call
+// for the given network type.
 func canUseConnectEx(net string) bool {
 	switch net {
-	case "udp", "udp4", "udp6", "ip", "ip4", "ip6":
-		// ConnectEx windows API does not support connectionless sockets.
-		return false
-	}
-	return syscall.LoadConnectEx() == nil
-}
-
-func dial(net string, ra Addr, dialer func(time.Time) (Conn, error), deadline time.Time) (Conn, error) {
-	if !canUseConnectEx(net) {
-		// Use the relatively inefficient goroutine-racing
-		// implementation of DialTimeout.
-		return dialChannel(net, ra, dialer, deadline)
+	case "tcp", "tcp4", "tcp6":
+		return true
 	}
-	return dialer(deadline)
+	// ConnectEx windows API does not support connectionless sockets.
+	return false
 }
 
 // operation contains superset of data necessary to perform all async IO.
@@ -152,7 +140,7 @@ func (s *ioSrv) ProcessRemoteIO() {
 func (s *ioSrv) ExecIO(o *operation, name string, submit func(o *operation) error) (int, error) {
 	fd := o.fd
 	// Notify runtime netpoll about starting IO.
-	err := fd.pd.Prepare(int(o.mode))
+	err := fd.pd.prepare(int(o.mode))
 	if err != nil {
 		return 0, err
 	}
@@ -180,7 +168,7 @@ func (s *ioSrv) ExecIO(o *operation, name string, submit func(o *operation) erro
 		return 0, err
 	}
 	// Wait for our request to complete.
-	err = fd.pd.Wait(int(o.mode))
+	err = fd.pd.wait(int(o.mode))
 	if err == nil {
 		// All is good. Extract our IO results and return.
 		if o.errno != 0 {
@@ -210,7 +198,7 @@ func (s *ioSrv) ExecIO(o *operation, name string, submit func(o *operation) erro
 		<-o.errc
 	}
 	// Wait for cancelation to complete.
-	fd.pd.WaitCanceled(int(o.mode))
+	fd.pd.waitCanceled(int(o.mode))
 	if o.errno != 0 {
 		err = syscall.Errno(o.errno)
 		if err == syscall.ERROR_OPERATION_ABORTED { // IO Canceled
@@ -273,7 +261,7 @@ func newFD(sysfd syscall.Handle, family, sotype int, net string) (*netFD, error)
 }
 
 func (fd *netFD) init() error {
-	if err := fd.pd.Init(fd); err != nil {
+	if err := fd.pd.init(fd); err != nil {
 		return err
 	}
 	if hasLoadSetFileCompletionNotificationModes {
@@ -320,19 +308,20 @@ func (fd *netFD) setAddr(laddr, raddr Addr) {
 	runtime.SetFinalizer(fd, (*netFD).Close)
 }
 
-func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-chan struct{}) error {
+func (fd *netFD) connect(ctx context.Context, la, ra syscall.Sockaddr) error {
 	// Do not need to call fd.writeLock here,
 	// because fd is not yet accessible to user,
 	// so no concurrent operations are possible.
 	if err := fd.init(); err != nil {
 		return err
 	}
-	if !deadline.IsZero() {
+	if deadline, ok := ctx.Deadline(); ok && !deadline.IsZero() {
 		fd.setWriteDeadline(deadline)
 		defer fd.setWriteDeadline(noDeadline)
 	}
 	if !canUseConnectEx(fd.net) {
-		return os.NewSyscallError("connect", connectFunc(fd.sysfd, ra))
+		err := connectFunc(fd.sysfd, ra)
+		return os.NewSyscallError("connect", err)
 	}
 	// ConnectEx windows API requires an unconnected, previously bound socket.
 	if la == nil {
@@ -351,26 +340,30 @@ func (fd *netFD) connect(la, ra syscall.Sockaddr, deadline time.Time, cancel <-c
 	// Call ConnectEx API.
 	o := &fd.wop
 	o.sa = ra
-	if cancel != nil {
-		done := make(chan struct{})
-		defer close(done)
-		go func() {
-			select {
-			case <-cancel:
-				// Force the runtime's poller to immediately give
-				// up waiting for writability.
-				fd.setWriteDeadline(aLongTimeAgo)
-			case <-done:
-			}
-		}()
-	}
+
+	// Wait for the goroutine converting context.Done into a write timeout
+	// to exist, otherwise our caller might cancel the context and
+	// cause fd.setWriteDeadline(aLongTimeAgo) to cancel a successful dial.
+	done := make(chan bool) // must be unbuffered
+	defer func() { done <- true }()
+	go func() {
+		select {
+		case <-ctx.Done():
+			// Force the runtime's poller to immediately give
+			// up waiting for writability.
+			fd.setWriteDeadline(aLongTimeAgo)
+			<-done
+		case <-done:
+		}
+	}()
+
 	_, err := wsrv.ExecIO(o, "ConnectEx", func(o *operation) error {
 		return connectExFunc(o.fd.sysfd, o.sa, nil, 0, nil, &o.o)
 	})
 	if err != nil {
 		select {
-		case <-cancel:
-			return errCanceled
+		case <-ctx.Done():
+			return mapErr(ctx.Err())
 		default:
 			if _, ok := err.(syscall.Errno); ok {
 				err = os.NewSyscallError("connectex", err)
@@ -388,68 +381,19 @@ func (fd *netFD) destroy() {
 	}
 	// Poller may want to unregister fd in readiness notification mechanism,
 	// so this must be executed before closeFunc.
-	fd.pd.Close()
+	fd.pd.close()
 	closeFunc(fd.sysfd)
 	fd.sysfd = syscall.InvalidHandle
 	// no need for a finalizer anymore
 	runtime.SetFinalizer(fd, nil)
 }
 
-// Add a reference to this fd.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) incref() error {
-	if !fd.fdmu.Incref() {
-		return errClosing
-	}
-	return nil
-}
-
-// Remove a reference to this FD and close if we've been asked to do so
-// (and there are no references left).
-func (fd *netFD) decref() {
-	if fd.fdmu.Decref() {
-		fd.destroy()
-	}
-}
-
-// Add a reference to this fd and lock for reading.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) readLock() error {
-	if !fd.fdmu.RWLock(true) {
-		return errClosing
-	}
-	return nil
-}
-
-// Unlock for reading and remove a reference to this FD.
-func (fd *netFD) readUnlock() {
-	if fd.fdmu.RWUnlock(true) {
-		fd.destroy()
-	}
-}
-
-// Add a reference to this fd and lock for writing.
-// Returns an error if the fd cannot be used.
-func (fd *netFD) writeLock() error {
-	if !fd.fdmu.RWLock(false) {
-		return errClosing
-	}
-	return nil
-}
-
-// Unlock for writing and remove a reference to this FD.
-func (fd *netFD) writeUnlock() {
-	if fd.fdmu.RWUnlock(false) {
-		fd.destroy()
-	}
-}
-
 func (fd *netFD) Close() error {
-	if !fd.fdmu.IncrefAndClose() {
+	if !fd.fdmu.increfAndClose() {
 		return errClosing
 	}
 	// unblock pending reader and writer
-	fd.pd.Evict()
+	fd.pd.evict()
 	fd.decref()
 	return nil
 }
@@ -483,7 +427,9 @@ func (fd *netFD) Read(buf []byte) (int, error) {
 	if race.Enabled {
 		race.Acquire(unsafe.Pointer(&ioSync))
 	}
-	err = fd.eofError(n, err)
+	if len(buf) != 0 {
+		err = fd.eofError(n, err)
+	}
 	if _, ok := err.(syscall.Errno); ok {
 		err = os.NewSyscallError("wsarecv", err)
 	}
@@ -579,7 +525,7 @@ func (fd *netFD) acceptOne(rawsa []syscall.RawSockaddrAny, o *operation) (*netFD
 	o.handle = s
 	o.rsan = int32(unsafe.Sizeof(rawsa[0]))
 	_, err = rsrv.ExecIO(o, "AcceptEx", func(o *operation) error {
-		return syscall.AcceptEx(o.fd.sysfd, o.handle, (*byte)(unsafe.Pointer(&rawsa[0])), 0, uint32(o.rsan), uint32(o.rsan), &o.qty, &o.o)
+		return acceptFunc(o.fd.sysfd, o.handle, (*byte)(unsafe.Pointer(&rawsa[0])), 0, uint32(o.rsan), uint32(o.rsan), &o.qty, &o.o)
 	})
 	if err != nil {
 		netfd.Close()
diff --git a/libgo/go/net/file_plan9.go b/libgo/go/net/file_plan9.go
index 892775a024f..2939c09a430 100644
--- a/libgo/go/net/file_plan9.go
+++ b/libgo/go/net/file_plan9.go
@@ -50,9 +50,7 @@ func newFileFD(f *os.File) (net *netFD, err error) {
 	name := comp[2]
 	switch file := comp[n-1]; file {
 	case "ctl", "clone":
-		syscall.ForkLock.RLock()
 		fd, err := syscall.Dup(int(f.Fd()), -1)
-		syscall.ForkLock.RUnlock()
 		if err != nil {
 			return nil, os.NewSyscallError("dup", err)
 		}
@@ -60,7 +58,7 @@ func newFileFD(f *os.File) (net *netFD, err error) {
 
 		dir := netdir + "/" + comp[n-2]
 		ctl = os.NewFile(uintptr(fd), dir+"/"+file)
-		ctl.Seek(0, 0)
+		ctl.Seek(0, io.SeekStart)
 		var buf [16]byte
 		n, err := ctl.Read(buf[:])
 		if err != nil {
diff --git a/libgo/go/net/hook.go b/libgo/go/net/hook.go
index 9ab34c0e36f..d7316ea4383 100644
--- a/libgo/go/net/hook.go
+++ b/libgo/go/net/hook.go
@@ -4,9 +4,19 @@
 
 package net
 
+import "context"
+
 var (
-	testHookDialTCP      = dialTCP
-	testHookHostsPath    = "/etc/hosts"
-	testHookLookupIP     = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) { return fn(host) }
+	// if non-nil, overrides dialTCP.
+	testHookDialTCP func(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error)
+
+	testHookHostsPath = "/etc/hosts"
+	testHookLookupIP  = func(
+		ctx context.Context,
+		fn func(context.Context, string) ([]IPAddr, error),
+		host string,
+	) ([]IPAddr, error) {
+		return fn(ctx, host)
+	}
 	testHookSetKeepAlive = func() {}
 )
diff --git a/libgo/go/net/hook_windows.go b/libgo/go/net/hook_windows.go
index 126b0ebdd10..63ea35ab8c4 100644
--- a/libgo/go/net/hook_windows.go
+++ b/libgo/go/net/hook_windows.go
@@ -13,9 +13,10 @@ var (
 	testHookDialChannel = func() { time.Sleep(time.Millisecond) } // see golang.org/issue/5349
 
 	// Placeholders for socket system calls.
-	socketFunc    func(int, int, int) (syscall.Handle, error)                                               = syscall.Socket
-	closeFunc     func(syscall.Handle) error                                                                = syscall.Closesocket
-	connectFunc   func(syscall.Handle, syscall.Sockaddr) error                                              = syscall.Connect
-	connectExFunc func(syscall.Handle, syscall.Sockaddr, *byte, uint32, *uint32, *syscall.Overlapped) error = syscall.ConnectEx
-	listenFunc    func(syscall.Handle, int) error                                                           = syscall.Listen
+	socketFunc    func(int, int, int) (syscall.Handle, error)                                                             = syscall.Socket
+	closeFunc     func(syscall.Handle) error                                                                              = syscall.Closesocket
+	connectFunc   func(syscall.Handle, syscall.Sockaddr) error                                                            = syscall.Connect
+	connectExFunc func(syscall.Handle, syscall.Sockaddr, *byte, uint32, *uint32, *syscall.Overlapped) error               = syscall.ConnectEx
+	listenFunc    func(syscall.Handle, int) error                                                                         = syscall.Listen
+	acceptFunc    func(syscall.Handle, syscall.Handle, *byte, uint32, uint32, uint32, *uint32, *syscall.Overlapped) error = syscall.AcceptEx
 )
diff --git a/libgo/go/net/hosts.go b/libgo/go/net/hosts.go
index c4de1b6a972..9c101c6ef5b 100644
--- a/libgo/go/net/hosts.go
+++ b/libgo/go/net/hosts.go
@@ -110,7 +110,9 @@ func lookupStaticHost(host string) []string {
 		lowerHost := []byte(host)
 		lowerASCIIBytes(lowerHost)
 		if ips, ok := hosts.byName[absDomainName(lowerHost)]; ok {
-			return ips
+			ipsCp := make([]string, len(ips))
+			copy(ipsCp, ips)
+			return ipsCp
 		}
 	}
 	return nil
@@ -127,7 +129,9 @@ func lookupStaticAddr(addr string) []string {
 	}
 	if len(hosts.byAddr) != 0 {
 		if hosts, ok := hosts.byAddr[addr]; ok {
-			return hosts
+			hostsCp := make([]string, len(hosts))
+			copy(hostsCp, hosts)
+			return hostsCp
 		}
 	}
 	return nil
diff --git a/libgo/go/net/hosts_test.go b/libgo/go/net/hosts_test.go
index 4c67bfa9824..5d6c9cfe190 100644
--- a/libgo/go/net/hosts_test.go
+++ b/libgo/go/net/hosts_test.go
@@ -64,13 +64,17 @@ func TestLookupStaticHost(t *testing.T) {
 	for _, tt := range lookupStaticHostTests {
 		testHookHostsPath = tt.name
 		for _, ent := range tt.ents {
-			ins := []string{ent.in, absDomainName([]byte(ent.in)), strings.ToLower(ent.in), strings.ToUpper(ent.in)}
-			for _, in := range ins {
-				addrs := lookupStaticHost(in)
-				if !reflect.DeepEqual(addrs, ent.out) {
-					t.Errorf("%s, lookupStaticHost(%s) = %v; want %v", tt.name, in, addrs, ent.out)
-				}
-			}
+			testStaticHost(t, tt.name, ent)
+		}
+	}
+}
+
+func testStaticHost(t *testing.T, hostsPath string, ent staticHostEntry) {
+	ins := []string{ent.in, absDomainName([]byte(ent.in)), strings.ToLower(ent.in), strings.ToUpper(ent.in)}
+	for _, in := range ins {
+		addrs := lookupStaticHost(in)
+		if !reflect.DeepEqual(addrs, ent.out) {
+			t.Errorf("%s, lookupStaticHost(%s) = %v; want %v", hostsPath, in, addrs, ent.out)
 		}
 	}
 }
@@ -129,13 +133,43 @@ func TestLookupStaticAddr(t *testing.T) {
 	for _, tt := range lookupStaticAddrTests {
 		testHookHostsPath = tt.name
 		for _, ent := range tt.ents {
-			hosts := lookupStaticAddr(ent.in)
-			for i := range ent.out {
-				ent.out[i] = absDomainName([]byte(ent.out[i]))
-			}
-			if !reflect.DeepEqual(hosts, ent.out) {
-				t.Errorf("%s, lookupStaticAddr(%s) = %v; want %v", tt.name, ent.in, hosts, ent.out)
-			}
+			testStaticAddr(t, tt.name, ent)
 		}
 	}
 }
+
+func testStaticAddr(t *testing.T, hostsPath string, ent staticHostEntry) {
+	hosts := lookupStaticAddr(ent.in)
+	for i := range ent.out {
+		ent.out[i] = absDomainName([]byte(ent.out[i]))
+	}
+	if !reflect.DeepEqual(hosts, ent.out) {
+		t.Errorf("%s, lookupStaticAddr(%s) = %v; want %v", hostsPath, ent.in, hosts, ent.out)
+	}
+}
+
+func TestHostCacheModification(t *testing.T) {
+	// Ensure that programs can't modify the internals of the host cache.
+	// See https://github.com/golang/go/issues/14212.
+	defer func(orig string) { testHookHostsPath = orig }(testHookHostsPath)
+
+	testHookHostsPath = "testdata/ipv4-hosts"
+	ent := staticHostEntry{"localhost", []string{"127.0.0.1", "127.0.0.2", "127.0.0.3"}}
+	testStaticHost(t, testHookHostsPath, ent)
+	// Modify the addresses return by lookupStaticHost.
+	addrs := lookupStaticHost(ent.in)
+	for i := range addrs {
+		addrs[i] += "junk"
+	}
+	testStaticHost(t, testHookHostsPath, ent)
+
+	testHookHostsPath = "testdata/ipv6-hosts"
+	ent = staticHostEntry{"::1", []string{"localhost"}}
+	testStaticAddr(t, testHookHostsPath, ent)
+	// Modify the hosts return by lookupStaticAddr.
+	hosts := lookupStaticAddr(ent.in)
+	for i := range hosts {
+		hosts[i] += "junk"
+	}
+	testStaticAddr(t, testHookHostsPath, ent)
+}
diff --git a/libgo/go/net/http/cgi/host.go b/libgo/go/net/http/cgi/host.go
index 9b4d8754183..58e9f7132a8 100644
--- a/libgo/go/net/http/cgi/host.go
+++ b/libgo/go/net/http/cgi/host.go
@@ -10,7 +10,7 @@
 //
 // Note that using CGI means starting a new process to handle each
 // request, which is typically less efficient than using a
-// long-running server.  This package is intended primarily for
+// long-running server. This package is intended primarily for
 // compatibility with existing systems.
 package cgi
 
@@ -58,6 +58,7 @@ type Handler struct {
 	InheritEnv []string    // environment variables to inherit from host, as "key"
 	Logger     *log.Logger // optional log for errors or nil to use log.Print
 	Args       []string    // optional arguments to pass to child process
+	Stderr     io.Writer   // optional stderr for the child process; nil means os.Stderr
 
 	// PathLocationHandler specifies the root http Handler that
 	// should handle internal redirects when the CGI process
@@ -70,6 +71,13 @@ type Handler struct {
 	PathLocationHandler http.Handler
 }
 
+func (h *Handler) stderr() io.Writer {
+	if h.Stderr != nil {
+		return h.Stderr
+	}
+	return os.Stderr
+}
+
 // removeLeadingDuplicates remove leading duplicate in environments.
 // It's possible to override environment like following.
 //    cgi.Handler{
@@ -145,6 +153,10 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 
 	for k, v := range req.Header {
 		k = strings.Map(upperCaseAndUnderscore, k)
+		if k == "PROXY" {
+			// See Issue 16405
+			continue
+		}
 		joinStr := ", "
 		if k == "COOKIE" {
 			joinStr = "; "
@@ -204,7 +216,7 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 		Args:   append([]string{h.Path}, h.Args...),
 		Dir:    cwd,
 		Env:    env,
-		Stderr: os.Stderr, // for now
+		Stderr: h.stderr(),
 	}
 	if req.ContentLength != 0 {
 		cmd.Stdin = req.Body
diff --git a/libgo/go/net/http/cgi/host_test.go b/libgo/go/net/http/cgi/host_test.go
index fb7d66adb9f..f0583729eba 100644
--- a/libgo/go/net/http/cgi/host_test.go
+++ b/libgo/go/net/http/cgi/host_test.go
@@ -8,6 +8,7 @@ package cgi
 
 import (
 	"bufio"
+	"bytes"
 	"fmt"
 	"io"
 	"net"
@@ -34,15 +35,18 @@ func newRequest(httpreq string) *http.Request {
 	return req
 }
 
-func runCgiTest(t *testing.T, h *Handler, httpreq string, expectedMap map[string]string) *httptest.ResponseRecorder {
+func runCgiTest(t *testing.T, h *Handler,
+	httpreq string,
+	expectedMap map[string]string, checks ...func(reqInfo map[string]string)) *httptest.ResponseRecorder {
 	rw := httptest.NewRecorder()
 	req := newRequest(httpreq)
 	h.ServeHTTP(rw, req)
-	runResponseChecks(t, rw, expectedMap)
+	runResponseChecks(t, rw, expectedMap, checks...)
 	return rw
 }
 
-func runResponseChecks(t *testing.T, rw *httptest.ResponseRecorder, expectedMap map[string]string) {
+func runResponseChecks(t *testing.T, rw *httptest.ResponseRecorder,
+	expectedMap map[string]string, checks ...func(reqInfo map[string]string)) {
 	// Make a map to hold the test map that the CGI returns.
 	m := make(map[string]string)
 	m["_body"] = rw.Body.String()
@@ -80,6 +84,9 @@ readlines:
 			t.Errorf("for key %q got %q; expected %q", key, got, expected)
 		}
 	}
+	for _, check := range checks {
+		check(m)
+	}
 }
 
 var cgiTested, cgiWorks bool
@@ -235,6 +242,31 @@ func TestDupHeaders(t *testing.T) {
 		expectedMap)
 }
 
+// Issue 16405: CGI+http.Transport differing uses of HTTP_PROXY.
+// Verify we don't set the HTTP_PROXY environment variable.
+// Hope nobody was depending on it. It's not a known header, though.
+func TestDropProxyHeader(t *testing.T) {
+	check(t)
+	h := &Handler{
+		Path: "testdata/test.cgi",
+	}
+	expectedMap := map[string]string{
+		"env-REQUEST_URI":     "/myscript/bar?a=b",
+		"env-SCRIPT_FILENAME": "testdata/test.cgi",
+		"env-HTTP_X_FOO":      "a",
+	}
+	runCgiTest(t, h, "GET /myscript/bar?a=b HTTP/1.0\n"+
+		"X-Foo: a\n"+
+		"Proxy: should_be_stripped\n"+
+		"Host: example.com\n\n",
+		expectedMap,
+		func(reqInfo map[string]string) {
+			if v, ok := reqInfo["env-HTTP_PROXY"]; ok {
+				t.Errorf("HTTP_PROXY = %q; should be absent", v)
+			}
+		})
+}
+
 func TestPathInfoNoRoot(t *testing.T) {
 	check(t)
 	h := &Handler{
@@ -501,6 +533,23 @@ func TestEnvOverride(t *testing.T) {
 	runCgiTest(t, h, "GET /test.cgi HTTP/1.0\nHost: example.com\n\n", expectedMap)
 }
 
+func TestHandlerStderr(t *testing.T) {
+	check(t)
+	var stderr bytes.Buffer
+	h := &Handler{
+		Path:   "testdata/test.cgi",
+		Root:   "/test.cgi",
+		Stderr: &stderr,
+	}
+
+	rw := httptest.NewRecorder()
+	req := newRequest("GET /test.cgi?writestderr=1 HTTP/1.0\nHost: example.com\n\n")
+	h.ServeHTTP(rw, req)
+	if got, want := stderr.String(), "Hello, stderr!\n"; got != want {
+		t.Errorf("Stderr = %q; want %q", got, want)
+	}
+}
+
 func TestRemoveLeadingDuplicates(t *testing.T) {
 	tests := []struct {
 		env  []string
diff --git a/libgo/go/net/http/cgi/testdata/test.cgi b/libgo/go/net/http/cgi/testdata/test.cgi
index ec7ee6f3864..667fce217ea 100644
--- a/libgo/go/net/http/cgi/testdata/test.cgi
+++ b/libgo/go/net/http/cgi/testdata/test.cgi
@@ -23,6 +23,10 @@ print "X-CGI-Pid: $$\r\n";
 print "X-Test-Header: X-Test-Value\r\n";
 print "\r\n";
 
+if ($params->{"writestderr"}) {
+    print STDERR "Hello, stderr!\n";
+}
+
 if ($params->{"bigresponse"}) {
     # 17 MB, for OS X: golang.org/issue/4958
     for (1..(17 * 1024)) {
diff --git a/libgo/go/net/http/client.go b/libgo/go/net/http/client.go
index 3106d229da6..993c247eef5 100644
--- a/libgo/go/net/http/client.go
+++ b/libgo/go/net/http/client.go
@@ -44,9 +44,12 @@ type Client struct {
 	// following an HTTP redirect. The arguments req and via are
 	// the upcoming request and the requests made already, oldest
 	// first. If CheckRedirect returns an error, the Client's Get
-	// method returns both the previous Response and
-	// CheckRedirect's error (wrapped in a url.Error) instead of
-	// issuing the Request req.
+	// method returns both the previous Response (with its Body
+	// closed) and CheckRedirect's error (wrapped in a url.Error)
+	// instead of issuing the Request req.
+	// As a special case, if CheckRedirect returns ErrUseLastResponse,
+	// then the most recent response is returned with its body
+	// unclosed, along with a nil error.
 	//
 	// If CheckRedirect is nil, the Client uses its default policy,
 	// which is to stop after 10 consecutive requests.
@@ -110,10 +113,6 @@ type RoundTripper interface {
 	RoundTrip(*Request) (*Response, error)
 }
 
-// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
-// return true if the string includes a port.
-func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
-
 // refererForURL returns a referer without any authentication info or
 // an empty string if lastReq scheme is https and newReq scheme is http.
 func refererForURL(lastReq, newReq *url.URL) string {
@@ -138,14 +137,6 @@ func refererForURL(lastReq, newReq *url.URL) string {
 	return referer
 }
 
-// Used in Send to implement io.ReadCloser by bundling together the
-// bufio.Reader through which we read the response, and the underlying
-// network connection.
-type readClose struct {
-	io.Reader
-	io.Closer
-}
-
 func (c *Client) send(req *Request, deadline time.Time) (*Response, error) {
 	if c.Jar != nil {
 		for _, cookie := range c.Jar.Cookies(req.URL) {
@@ -161,28 +152,33 @@ func (c *Client) send(req *Request, deadline time.Time) (*Response, error) {
 			c.Jar.SetCookies(req.URL, rc)
 		}
 	}
-	return resp, err
+	return resp, nil
 }
 
 // Do sends an HTTP request and returns an HTTP response, following
-// policy (e.g. redirects, cookies, auth) as configured on the client.
+// policy (such as redirects, cookies, auth) as configured on the
+// client.
 //
 // An error is returned if caused by client policy (such as
-// CheckRedirect), or if there was an HTTP protocol error.
-// A non-2xx response doesn't cause an error.
-//
-// When err is nil, resp always contains a non-nil resp.Body.
+// CheckRedirect), or failure to speak HTTP (such as a network
+// connectivity problem). A non-2xx status code doesn't cause an
+// error.
 //
-// Callers should close resp.Body when done reading from it. If
-// resp.Body is not closed, the Client's underlying RoundTripper
-// (typically Transport) may not be able to re-use a persistent TCP
-// connection to the server for a subsequent "keep-alive" request.
+// If the returned error is nil, the Response will contain a non-nil
+// Body which the user is expected to close. If the Body is not
+// closed, the Client's underlying RoundTripper (typically Transport)
+// may not be able to re-use a persistent TCP connection to the server
+// for a subsequent "keep-alive" request.
 //
 // The request Body, if non-nil, will be closed by the underlying
 // Transport, even on errors.
 //
+// On error, any Response can be ignored. A non-nil Response with a
+// non-nil error only occurs when CheckRedirect fails, and even then
+// the returned Response.Body is already closed.
+//
 // Generally Get, Post, or PostForm will be used instead of Do.
-func (c *Client) Do(req *Request) (resp *Response, err error) {
+func (c *Client) Do(req *Request) (*Response, error) {
 	method := valueOrDefault(req.Method, "GET")
 	if method == "GET" || method == "HEAD" {
 		return c.doFollowingRedirects(req, shouldRedirectGet)
@@ -237,7 +233,7 @@ func send(ireq *Request, rt RoundTripper, deadline time.Time) (*Response, error)
 	}
 
 	// Most the callers of send (Get, Post, et al) don't need
-	// Headers, leaving it uninitialized.  We guarantee to the
+	// Headers, leaving it uninitialized. We guarantee to the
 	// Transport that this has been initialized, though.
 	if req.Header == nil {
 		forkReq()
@@ -424,101 +420,125 @@ func (c *Client) Get(url string) (resp *Response, err error) {
 
 func alwaysFalse() bool { return false }
 
-func (c *Client) doFollowingRedirects(ireq *Request, shouldRedirect func(int) bool) (resp *Response, err error) {
-	var base *url.URL
-	redirectChecker := c.CheckRedirect
-	if redirectChecker == nil {
-		redirectChecker = defaultCheckRedirect
+// ErrUseLastResponse can be returned by Client.CheckRedirect hooks to
+// control how redirects are processed. If returned, the next request
+// is not sent and the most recent response is returned with its body
+// unclosed.
+var ErrUseLastResponse = errors.New("net/http: use last response")
+
+// checkRedirect calls either the user's configured CheckRedirect
+// function, or the default.
+func (c *Client) checkRedirect(req *Request, via []*Request) error {
+	fn := c.CheckRedirect
+	if fn == nil {
+		fn = defaultCheckRedirect
 	}
-	var via []*Request
+	return fn(req, via)
+}
 
-	if ireq.URL == nil {
-		ireq.closeBody()
+func (c *Client) doFollowingRedirects(req *Request, shouldRedirect func(int) bool) (*Response, error) {
+	if req.URL == nil {
+		req.closeBody()
 		return nil, errors.New("http: nil Request.URL")
 	}
 
-	req := ireq
-	deadline := c.deadline()
-
-	urlStr := "" // next relative or absolute URL to fetch (after first request)
-	redirectFailed := false
-	for redirect := 0; ; redirect++ {
-		if redirect != 0 {
-			nreq := new(Request)
-			nreq.Cancel = ireq.Cancel
-			nreq.Method = ireq.Method
-			if ireq.Method == "POST" || ireq.Method == "PUT" {
-				nreq.Method = "GET"
+	var (
+		deadline = c.deadline()
+		reqs     []*Request
+		resp     *Response
+	)
+	uerr := func(err error) error {
+		req.closeBody()
+		method := valueOrDefault(reqs[0].Method, "GET")
+		var urlStr string
+		if resp != nil && resp.Request != nil {
+			urlStr = resp.Request.URL.String()
+		} else {
+			urlStr = req.URL.String()
+		}
+		return &url.Error{
+			Op:  method[:1] + strings.ToLower(method[1:]),
+			URL: urlStr,
+			Err: err,
+		}
+	}
+	for {
+		// For all but the first request, create the next
+		// request hop and replace req.
+		if len(reqs) > 0 {
+			loc := resp.Header.Get("Location")
+			if loc == "" {
+				return nil, uerr(fmt.Errorf("%d response missing Location header", resp.StatusCode))
 			}
-			nreq.Header = make(Header)
-			nreq.URL, err = base.Parse(urlStr)
+			u, err := req.URL.Parse(loc)
 			if err != nil {
-				break
+				return nil, uerr(fmt.Errorf("failed to parse Location header %q: %v", loc, err))
 			}
-			if len(via) > 0 {
-				// Add the Referer header.
-				lastReq := via[len(via)-1]
-				if ref := refererForURL(lastReq.URL, nreq.URL); ref != "" {
-					nreq.Header.Set("Referer", ref)
-				}
-
-				err = redirectChecker(nreq, via)
-				if err != nil {
-					redirectFailed = true
-					break
-				}
+			ireq := reqs[0]
+			req = &Request{
+				Method:   ireq.Method,
+				Response: resp,
+				URL:      u,
+				Header:   make(Header),
+				Cancel:   ireq.Cancel,
+				ctx:      ireq.ctx,
 			}
-			req = nreq
-		}
+			if ireq.Method == "POST" || ireq.Method == "PUT" {
+				req.Method = "GET"
+			}
+			// Add the Referer header from the most recent
+			// request URL to the new one, if it's not https->http:
+			if ref := refererForURL(reqs[len(reqs)-1].URL, req.URL); ref != "" {
+				req.Header.Set("Referer", ref)
+			}
+			err = c.checkRedirect(req, reqs)
 
-		urlStr = req.URL.String()
-		if resp, err = c.send(req, deadline); err != nil {
-			if !deadline.IsZero() && !time.Now().Before(deadline) {
-				err = &httpError{
-					err:     err.Error() + " (Client.Timeout exceeded while awaiting headers)",
-					timeout: true,
-				}
+			// Sentinel error to let users select the
+			// previous response, without closing its
+			// body. See Issue 10069.
+			if err == ErrUseLastResponse {
+				return resp, nil
 			}
-			break
-		}
 
-		if shouldRedirect(resp.StatusCode) {
-			// Read the body if small so underlying TCP connection will be re-used.
-			// No need to check for errors: if it fails, Transport won't reuse it anyway.
+			// Close the previous response's body. But
+			// read at least some of the body so if it's
+			// small the underlying TCP connection will be
+			// re-used. No need to check for errors: if it
+			// fails, the Transport won't reuse it anyway.
 			const maxBodySlurpSize = 2 << 10
 			if resp.ContentLength == -1 || resp.ContentLength <= maxBodySlurpSize {
 				io.CopyN(ioutil.Discard, resp.Body, maxBodySlurpSize)
 			}
 			resp.Body.Close()
-			if urlStr = resp.Header.Get("Location"); urlStr == "" {
-				err = fmt.Errorf("%d response missing Location header", resp.StatusCode)
-				break
+
+			if err != nil {
+				// Special case for Go 1 compatibility: return both the response
+				// and an error if the CheckRedirect function failed.
+				// See https://golang.org/issue/3795
+				// The resp.Body has already been closed.
+				ue := uerr(err)
+				ue.(*url.Error).URL = loc
+				return resp, ue
 			}
-			base = req.URL
-			via = append(via, req)
-			continue
 		}
-		return resp, nil
-	}
 
-	method := valueOrDefault(ireq.Method, "GET")
-	urlErr := &url.Error{
-		Op:  method[:1] + strings.ToLower(method[1:]),
-		URL: urlStr,
-		Err: err,
-	}
+		reqs = append(reqs, req)
 
-	if redirectFailed {
-		// Special case for Go 1 compatibility: return both the response
-		// and an error if the CheckRedirect function failed.
-		// See https://golang.org/issue/3795
-		return resp, urlErr
-	}
+		var err error
+		if resp, err = c.send(req, deadline); err != nil {
+			if !deadline.IsZero() && !time.Now().Before(deadline) {
+				err = &httpError{
+					err:     err.Error() + " (Client.Timeout exceeded while awaiting headers)",
+					timeout: true,
+				}
+			}
+			return nil, uerr(err)
+		}
 
-	if resp != nil {
-		resp.Body.Close()
+		if !shouldRedirect(resp.StatusCode) {
+			return resp, nil
+		}
 	}
-	return nil, urlErr
 }
 
 func defaultCheckRedirect(req *Request, via []*Request) error {
diff --git a/libgo/go/net/http/client_test.go b/libgo/go/net/http/client_test.go
index 8939dc8baf9..a9b1948005c 100644
--- a/libgo/go/net/http/client_test.go
+++ b/libgo/go/net/http/client_test.go
@@ -8,6 +8,7 @@ package http_test
 
 import (
 	"bytes"
+	"context"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/base64"
@@ -273,7 +274,7 @@ func TestClientRedirects(t *testing.T) {
 		t.Fatal("didn't see redirect")
 	}
 	if lastReq.Cancel != cancel {
-		t.Errorf("expected lastReq to have the cancel channel set on the inital req")
+		t.Errorf("expected lastReq to have the cancel channel set on the initial req")
 	}
 
 	checkErr = errors.New("no redirects allowed")
@@ -290,6 +291,33 @@ func TestClientRedirects(t *testing.T) {
 	}
 }
 
+func TestClientRedirectContext(t *testing.T) {
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		Redirect(w, r, "/", StatusFound)
+	}))
+	defer ts.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	c := &Client{CheckRedirect: func(req *Request, via []*Request) error {
+		cancel()
+		if len(via) > 2 {
+			return errors.New("too many redirects")
+		}
+		return nil
+	}}
+	req, _ := NewRequest("GET", ts.URL, nil)
+	req = req.WithContext(ctx)
+	_, err := c.Do(req)
+	ue, ok := err.(*url.Error)
+	if !ok {
+		t.Fatalf("got error %T; want *url.Error", err)
+	}
+	if ue.Err != ExportErrRequestCanceled && ue.Err != ExportErrRequestCanceledConn {
+		t.Errorf("url.Error.Err = %v; want errRequestCanceled or errRequestCanceledConn", ue.Err)
+	}
+}
+
 func TestPostRedirects(t *testing.T) {
 	defer afterTest(t)
 	var log struct {
@@ -338,6 +366,44 @@ func TestPostRedirects(t *testing.T) {
 	}
 }
 
+func TestClientRedirectUseResponse(t *testing.T) {
+	defer afterTest(t)
+	const body = "Hello, world."
+	var ts *httptest.Server
+	ts = httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		if strings.Contains(r.URL.Path, "/other") {
+			io.WriteString(w, "wrong body")
+		} else {
+			w.Header().Set("Location", ts.URL+"/other")
+			w.WriteHeader(StatusFound)
+			io.WriteString(w, body)
+		}
+	}))
+	defer ts.Close()
+
+	c := &Client{CheckRedirect: func(req *Request, via []*Request) error {
+		if req.Response == nil {
+			t.Error("expected non-nil Request.Response")
+		}
+		return ErrUseLastResponse
+	}}
+	res, err := c.Get(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.StatusCode != StatusFound {
+		t.Errorf("status = %d; want %d", res.StatusCode, StatusFound)
+	}
+	defer res.Body.Close()
+	slurp, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(slurp) != body {
+		t.Errorf("body = %q; want %q", slurp, body)
+	}
+}
+
 var expectedCookies = []*Cookie{
 	{Name: "ChocolateChip", Value: "tasty"},
 	{Name: "First", Value: "Hit"},
@@ -1140,3 +1206,26 @@ func TestReferer(t *testing.T) {
 		}
 	}
 }
+
+// issue15577Tripper returns a Response with a redirect response
+// header and doesn't populate its Response.Request field.
+type issue15577Tripper struct{}
+
+func (issue15577Tripper) RoundTrip(*Request) (*Response, error) {
+	resp := &Response{
+		StatusCode: 303,
+		Header:     map[string][]string{"Location": {"http://www.example.com/"}},
+		Body:       ioutil.NopCloser(strings.NewReader("")),
+	}
+	return resp, nil
+}
+
+// Issue 15577: don't assume the roundtripper's response populates its Request field.
+func TestClientRedirectResponseWithoutRequest(t *testing.T) {
+	c := &Client{
+		CheckRedirect: func(*Request, []*Request) error { return fmt.Errorf("no redirects!") },
+		Transport:     issue15577Tripper{},
+	}
+	// Check that this doesn't crash:
+	c.Get("http://dummy.tld")
+}
diff --git a/libgo/go/net/http/clientserver_test.go b/libgo/go/net/http/clientserver_test.go
index aa2473a2773..3d1f09cae83 100644
--- a/libgo/go/net/http/clientserver_test.go
+++ b/libgo/go/net/http/clientserver_test.go
@@ -17,6 +17,7 @@ import (
 	"net"
 	. "net/http"
 	"net/http/httptest"
+	"net/http/httputil"
 	"net/url"
 	"os"
 	"reflect"
@@ -43,6 +44,13 @@ func (t *clientServerTest) close() {
 	t.ts.Close()
 }
 
+func (t *clientServerTest) scheme() string {
+	if t.h2 {
+		return "https"
+	}
+	return "http"
+}
+
 const (
 	h1Mode = false
 	h2Mode = true
@@ -147,10 +155,11 @@ type reqFunc func(c *Client, url string) (*Response, error)
 // h12Compare is a test that compares HTTP/1 and HTTP/2 behavior
 // against each other.
 type h12Compare struct {
-	Handler       func(ResponseWriter, *Request)    // required
-	ReqFunc       reqFunc                           // optional
-	CheckResponse func(proto string, res *Response) // optional
-	Opts          []interface{}
+	Handler            func(ResponseWriter, *Request)    // required
+	ReqFunc            reqFunc                           // optional
+	CheckResponse      func(proto string, res *Response) // optional
+	EarlyCheckResponse func(proto string, res *Response) // optional; pre-normalize
+	Opts               []interface{}
 }
 
 func (tt h12Compare) reqFunc() reqFunc {
@@ -176,6 +185,12 @@ func (tt h12Compare) run(t *testing.T) {
 		t.Errorf("HTTP/2 request: %v", err)
 		return
 	}
+
+	if fn := tt.EarlyCheckResponse; fn != nil {
+		fn("HTTP/1.1", res1)
+		fn("HTTP/2.0", res2)
+	}
+
 	tt.normalizeRes(t, res1, "HTTP/1.1")
 	tt.normalizeRes(t, res2, "HTTP/2.0")
 	res1body, res2body := res1.Body, res2.Body
@@ -220,6 +235,7 @@ func (tt h12Compare) normalizeRes(t *testing.T, res *Response, wantProto string)
 		t.Errorf("got %q response; want %q", res.Proto, wantProto)
 	}
 	slurp, err := ioutil.ReadAll(res.Body)
+
 	res.Body.Close()
 	res.Body = slurpResult{
 		ReadCloser: ioutil.NopCloser(bytes.NewReader(slurp)),
@@ -356,7 +372,7 @@ func TestH12_HandlerWritesTooLittle(t *testing.T) {
 }
 
 // Tests that the HTTP/1 and HTTP/2 servers prevent handlers from
-// writing more than they declared.  This test does not test whether
+// writing more than they declared. This test does not test whether
 // the transport deals with too much data, though, since the server
 // doesn't make it possible to send bogus data. For those tests, see
 // transport_test.go (for HTTP/1) or x/net/http2/transport_test.go
@@ -1049,6 +1065,170 @@ func testTransportGCRequest(t *testing.T, h2, body bool) {
 	}
 }
 
+func TestTransportRejectsInvalidHeaders_h1(t *testing.T) {
+	testTransportRejectsInvalidHeaders(t, h1Mode)
+}
+func TestTransportRejectsInvalidHeaders_h2(t *testing.T) {
+	testTransportRejectsInvalidHeaders(t, h2Mode)
+}
+func testTransportRejectsInvalidHeaders(t *testing.T, h2 bool) {
+	defer afterTest(t)
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		fmt.Fprintf(w, "Handler saw headers: %q", r.Header)
+	}))
+	defer cst.close()
+	cst.tr.DisableKeepAlives = true
+
+	tests := []struct {
+		key, val string
+		ok       bool
+	}{
+		{"Foo", "capital-key", true}, // verify h2 allows capital keys
+		{"Foo", "foo\x00bar", false}, // \x00 byte in value not allowed
+		{"Foo", "two\nlines", false}, // \n byte in value not allowed
+		{"bogus\nkey", "v", false},   // \n byte also not allowed in key
+		{"A space", "v", false},      // spaces in keys not allowed
+		{"имя", "v", false},          // key must be ascii
+		{"name", "валю", true},       // value may be non-ascii
+		{"", "v", false},             // key must be non-empty
+		{"k", "", true},              // value may be empty
+	}
+	for _, tt := range tests {
+		dialedc := make(chan bool, 1)
+		cst.tr.Dial = func(netw, addr string) (net.Conn, error) {
+			dialedc <- true
+			return net.Dial(netw, addr)
+		}
+		req, _ := NewRequest("GET", cst.ts.URL, nil)
+		req.Header[tt.key] = []string{tt.val}
+		res, err := cst.c.Do(req)
+		var body []byte
+		if err == nil {
+			body, _ = ioutil.ReadAll(res.Body)
+			res.Body.Close()
+		}
+		var dialed bool
+		select {
+		case <-dialedc:
+			dialed = true
+		default:
+		}
+
+		if !tt.ok && dialed {
+			t.Errorf("For key %q, value %q, transport dialed. Expected local failure. Response was: (%v, %v)\nServer replied with: %s", tt.key, tt.val, res, err, body)
+		} else if (err == nil) != tt.ok {
+			t.Errorf("For key %q, value %q; got err = %v; want ok=%v", tt.key, tt.val, err, tt.ok)
+		}
+	}
+}
+
+// Tests that we support bogus under-100 HTTP statuses, because we historically
+// have. This might change at some point, but not yet in Go 1.6.
+func TestBogusStatusWorks_h1(t *testing.T) { testBogusStatusWorks(t, h1Mode) }
+func TestBogusStatusWorks_h2(t *testing.T) { testBogusStatusWorks(t, h2Mode) }
+func testBogusStatusWorks(t *testing.T, h2 bool) {
+	defer afterTest(t)
+	const code = 7
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.WriteHeader(code)
+	}))
+	defer cst.close()
+
+	res, err := cst.c.Get(cst.ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.StatusCode != code {
+		t.Errorf("StatusCode = %d; want %d", res.StatusCode, code)
+	}
+}
+
+func TestInterruptWithPanic_h1(t *testing.T) { testInterruptWithPanic(t, h1Mode) }
+func TestInterruptWithPanic_h2(t *testing.T) { testInterruptWithPanic(t, h2Mode) }
+func testInterruptWithPanic(t *testing.T, h2 bool) {
+	log.SetOutput(ioutil.Discard) // is noisy otherwise
+	defer log.SetOutput(os.Stderr)
+
+	const msg = "hello"
+	defer afterTest(t)
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		io.WriteString(w, msg)
+		w.(Flusher).Flush()
+		panic("no more")
+	}))
+	defer cst.close()
+	res, err := cst.c.Get(cst.ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer res.Body.Close()
+	slurp, err := ioutil.ReadAll(res.Body)
+	if string(slurp) != msg {
+		t.Errorf("client read %q; want %q", slurp, msg)
+	}
+	if err == nil {
+		t.Errorf("client read all successfully; want some error")
+	}
+}
+
+// Issue 15366
+func TestH12_AutoGzipWithDumpResponse(t *testing.T) {
+	h12Compare{
+		Handler: func(w ResponseWriter, r *Request) {
+			h := w.Header()
+			h.Set("Content-Encoding", "gzip")
+			h.Set("Content-Length", "23")
+			h.Set("Connection", "keep-alive")
+			io.WriteString(w, "\x1f\x8b\b\x00\x00\x00\x00\x00\x00\x00s\xf3\xf7\a\x00\xab'\xd4\x1a\x03\x00\x00\x00")
+		},
+		EarlyCheckResponse: func(proto string, res *Response) {
+			if !res.Uncompressed {
+				t.Errorf("%s: expected Uncompressed to be set", proto)
+			}
+			dump, err := httputil.DumpResponse(res, true)
+			if err != nil {
+				t.Errorf("%s: DumpResponse: %v", proto, err)
+				return
+			}
+			if strings.Contains(string(dump), "Connection: close") {
+				t.Errorf("%s: should not see \"Connection: close\" in dump; got:\n%s", proto, dump)
+			}
+			if !strings.Contains(string(dump), "FOO") {
+				t.Errorf("%s: should see \"FOO\" in response; got:\n%s", proto, dump)
+			}
+		},
+	}.run(t)
+}
+
+// Issue 14607
+func TestCloseIdleConnections_h1(t *testing.T) { testCloseIdleConnections(t, h1Mode) }
+func TestCloseIdleConnections_h2(t *testing.T) { testCloseIdleConnections(t, h2Mode) }
+func testCloseIdleConnections(t *testing.T, h2 bool) {
+	defer afterTest(t)
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.Header().Set("X-Addr", r.RemoteAddr)
+	}))
+	defer cst.close()
+	get := func() string {
+		res, err := cst.c.Get(cst.ts.URL)
+		if err != nil {
+			t.Fatal(err)
+		}
+		res.Body.Close()
+		v := res.Header.Get("X-Addr")
+		if v == "" {
+			t.Fatal("didn't get X-Addr")
+		}
+		return v
+	}
+	a1 := get()
+	cst.tr.CloseIdleConnections()
+	a2 := get()
+	if a1 == a2 {
+		t.Errorf("didn't close connection")
+	}
+}
+
 type noteCloseConn struct {
 	net.Conn
 	closeFunc func()
diff --git a/libgo/go/net/http/cookie.go b/libgo/go/net/http/cookie.go
index 648709dd997..1ea0e9397a3 100644
--- a/libgo/go/net/http/cookie.go
+++ b/libgo/go/net/http/cookie.go
@@ -223,7 +223,7 @@ func readCookies(h Header, filter string) []*Cookie {
 	return cookies
 }
 
-// validCookieDomain returns wheter v is a valid cookie domain-value.
+// validCookieDomain returns whether v is a valid cookie domain-value.
 func validCookieDomain(v string) bool {
 	if isCookieDomainName(v) {
 		return true
diff --git a/libgo/go/net/http/cookie_test.go b/libgo/go/net/http/cookie_test.go
index d474f313476..95e61479a15 100644
--- a/libgo/go/net/http/cookie_test.go
+++ b/libgo/go/net/http/cookie_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/http/cookiejar/punycode.go b/libgo/go/net/http/cookiejar/punycode.go
index ea7ceb5ef3f..a9cc666e8c9 100644
--- a/libgo/go/net/http/cookiejar/punycode.go
+++ b/libgo/go/net/http/cookiejar/punycode.go
@@ -37,7 +37,7 @@ func encode(prefix, s string) (string, error) {
 	delta, n, bias := int32(0), initialN, initialBias
 	b, remaining := int32(0), int32(0)
 	for _, r := range s {
-		if r < 0x80 {
+		if r < utf8.RuneSelf {
 			b++
 			output = append(output, byte(r))
 		} else {
diff --git a/libgo/go/net/http/export_test.go b/libgo/go/net/http/export_test.go
index 52bccbdce31..9c5ba0809ad 100644
--- a/libgo/go/net/http/export_test.go
+++ b/libgo/go/net/http/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -9,22 +9,22 @@ package http
 
 import (
 	"net"
+	"sort"
 	"sync"
 	"time"
 )
 
 var (
-	DefaultUserAgent              = defaultUserAgent
-	NewLoggingConn                = newLoggingConn
-	ExportAppendTime              = appendTime
-	ExportRefererForURL           = refererForURL
-	ExportServerNewConn           = (*Server).newConn
-	ExportCloseWriteAndWait       = (*conn).closeWriteAndWait
-	ExportErrRequestCanceled      = errRequestCanceled
-	ExportErrRequestCanceledConn  = errRequestCanceledConn
-	ExportServeFile               = serveFile
-	ExportHttp2ConfigureTransport = http2ConfigureTransport
-	ExportHttp2ConfigureServer    = http2ConfigureServer
+	DefaultUserAgent             = defaultUserAgent
+	NewLoggingConn               = newLoggingConn
+	ExportAppendTime             = appendTime
+	ExportRefererForURL          = refererForURL
+	ExportServerNewConn          = (*Server).newConn
+	ExportCloseWriteAndWait      = (*conn).closeWriteAndWait
+	ExportErrRequestCanceled     = errRequestCanceled
+	ExportErrRequestCanceledConn = errRequestCanceledConn
+	ExportServeFile              = serveFile
+	ExportHttp2ConfigureServer   = http2ConfigureServer
 )
 
 func init() {
@@ -35,9 +35,8 @@ func init() {
 }
 
 var (
-	SetEnterRoundTripHook  = hookSetter(&testHookEnterRoundTrip)
-	SetTestHookWaitResLoop = hookSetter(&testHookWaitResLoop)
-	SetRoundTripRetried    = hookSetter(&testHookRoundTripRetried)
+	SetEnterRoundTripHook = hookSetter(&testHookEnterRoundTrip)
+	SetRoundTripRetried   = hookSetter(&testHookRoundTripRetried)
 )
 
 func SetReadLoopBeforeNextReadHook(f func()) {
@@ -59,9 +58,9 @@ func SetTestHookServerServe(fn func(*Server, net.Listener)) { testHookServerServ
 
 func NewTestTimeoutHandler(handler Handler, ch <-chan time.Time) Handler {
 	return &timeoutHandler{
-		handler: handler,
-		timeout: func() <-chan time.Time { return ch },
-		// (no body and nil cancelTimer)
+		handler:     handler,
+		testTimeout: ch,
+		// (no body)
 	}
 }
 
@@ -81,21 +80,29 @@ func (t *Transport) IdleConnKeysForTesting() (keys []string) {
 	keys = make([]string, 0)
 	t.idleMu.Lock()
 	defer t.idleMu.Unlock()
-	if t.idleConn == nil {
-		return
-	}
 	for key := range t.idleConn {
 		keys = append(keys, key.String())
 	}
+	sort.Strings(keys)
 	return
 }
 
-func (t *Transport) IdleConnCountForTesting(cacheKey string) int {
+func (t *Transport) IdleConnStrsForTesting() []string {
+	var ret []string
 	t.idleMu.Lock()
 	defer t.idleMu.Unlock()
-	if t.idleConn == nil {
-		return 0
+	for _, conns := range t.idleConn {
+		for _, pc := range conns {
+			ret = append(ret, pc.conn.LocalAddr().String()+"/"+pc.conn.RemoteAddr().String())
+		}
 	}
+	sort.Strings(ret)
+	return ret
+}
+
+func (t *Transport) IdleConnCountForTesting(cacheKey string) int {
+	t.idleMu.Lock()
+	defer t.idleMu.Unlock()
 	for k, conns := range t.idleConn {
 		if k.String() == cacheKey {
 			return len(conns)
@@ -144,3 +151,12 @@ func hookSetter(dst *func()) func(func()) {
 		*dst = fn
 	}
 }
+
+func ExportHttp2ConfigureTransport(t *Transport) error {
+	t2, err := http2configureTransport(t)
+	if err != nil {
+		return err
+	}
+	t.h2transport = t2
+	return nil
+}
diff --git a/libgo/go/net/http/fcgi/fcgi.go b/libgo/go/net/http/fcgi/fcgi.go
index 06bba0488a2..337484139d3 100644
--- a/libgo/go/net/http/fcgi/fcgi.go
+++ b/libgo/go/net/http/fcgi/fcgi.go
@@ -58,8 +58,6 @@ const (
 	statusUnknownRole
 )
 
-const headerLen = 8
-
 type header struct {
 	Version       uint8
 	Type          recType
@@ -158,11 +156,6 @@ func (c *conn) writeRecord(recType recType, reqId uint16, b []byte) error {
 	return err
 }
 
-func (c *conn) writeBeginRequest(reqId uint16, role uint16, flags uint8) error {
-	b := [8]byte{byte(role >> 8), byte(role), flags}
-	return c.writeRecord(typeBeginRequest, reqId, b[:])
-}
-
 func (c *conn) writeEndRequest(reqId uint16, appStatus int, protocolStatus uint8) error {
 	b := make([]byte, 8)
 	binary.BigEndian.PutUint32(b, uint32(appStatus))
diff --git a/libgo/go/net/http/filetransport.go b/libgo/go/net/http/filetransport.go
index 821787e0c4b..32126d7ec0f 100644
--- a/libgo/go/net/http/filetransport.go
+++ b/libgo/go/net/http/filetransport.go
@@ -33,7 +33,7 @@ func NewFileTransport(fs FileSystem) RoundTripper {
 
 func (t fileTransport) RoundTrip(req *Request) (resp *Response, err error) {
 	// We start ServeHTTP in a goroutine, which may take a long
-	// time if the file is large.  The newPopulateResponseWriter
+	// time if the file is large. The newPopulateResponseWriter
 	// call returns a channel which either ServeHTTP or finish()
 	// sends our *Response on, once the *Response itself has been
 	// populated (even if the body itself is still being
diff --git a/libgo/go/net/http/fs.go b/libgo/go/net/http/fs.go
index f61c138c1d9..c7a58a61dff 100644
--- a/libgo/go/net/http/fs.go
+++ b/libgo/go/net/http/fs.go
@@ -34,7 +34,7 @@ import (
 type Dir string
 
 func (d Dir) Open(name string) (File, error) {
-	if filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0 ||
+	if filepath.Separator != '/' && strings.ContainsRune(name, filepath.Separator) ||
 		strings.Contains(name, "\x00") {
 		return nil, errors.New("http: invalid character in file path")
 	}
@@ -96,7 +96,7 @@ func dirList(w ResponseWriter, f File) {
 }
 
 // ServeContent replies to the request using the content in the
-// provided ReadSeeker.  The main benefit of ServeContent over io.Copy
+// provided ReadSeeker. The main benefit of ServeContent over io.Copy
 // is that it handles Range requests properly, sets the MIME type, and
 // handles If-Modified-Since requests.
 //
@@ -108,7 +108,7 @@ func dirList(w ResponseWriter, f File) {
 // never sent in the response.
 //
 // If modtime is not the zero time or Unix epoch, ServeContent
-// includes it in a Last-Modified header in the response.  If the
+// includes it in a Last-Modified header in the response. If the
 // request includes an If-Modified-Since header, ServeContent uses
 // modtime to decide whether the content needs to be sent at all.
 //
@@ -121,11 +121,11 @@ func dirList(w ResponseWriter, f File) {
 // Note that *os.File implements the io.ReadSeeker interface.
 func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker) {
 	sizeFunc := func() (int64, error) {
-		size, err := content.Seek(0, os.SEEK_END)
+		size, err := content.Seek(0, io.SeekEnd)
 		if err != nil {
 			return 0, errSeeker
 		}
-		_, err = content.Seek(0, os.SEEK_SET)
+		_, err = content.Seek(0, io.SeekStart)
 		if err != nil {
 			return 0, errSeeker
 		}
@@ -166,7 +166,7 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 			var buf [sniffLen]byte
 			n, _ := io.ReadFull(content, buf[:])
 			ctype = DetectContentType(buf[:n])
-			_, err := content.Seek(0, os.SEEK_SET) // rewind to output whole file
+			_, err := content.Seek(0, io.SeekStart) // rewind to output whole file
 			if err != nil {
 				Error(w, "seeker can't seek", StatusInternalServerError)
 				return
@@ -196,7 +196,7 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 			// The total number of bytes in all the ranges
 			// is larger than the size of the file by
 			// itself, so this is probably an attack, or a
-			// dumb client.  Ignore the range request.
+			// dumb client. Ignore the range request.
 			ranges = nil
 		}
 		switch {
@@ -213,7 +213,7 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 			// A response to a request for a single range MUST NOT
 			// be sent using the multipart/byteranges media type."
 			ra := ranges[0]
-			if _, err := content.Seek(ra.start, os.SEEK_SET); err != nil {
+			if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
 				Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
 				return
 			}
@@ -236,7 +236,7 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 						pw.CloseWithError(err)
 						return
 					}
-					if _, err := content.Seek(ra.start, os.SEEK_SET); err != nil {
+					if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
 						pw.CloseWithError(err)
 						return
 					}
@@ -291,7 +291,7 @@ func checkLastModified(w ResponseWriter, r *Request, modtime time.Time) bool {
 // checkETag implements If-None-Match and If-Range checks.
 //
 // The ETag or modtime must have been previously set in the
-// ResponseWriter's headers.  The modtime is only compared at second
+// ResponseWriter's headers. The modtime is only compared at second
 // granularity and may be the zero value to mean unknown.
 //
 // The return value is the effective request "Range" header to use and
@@ -336,7 +336,7 @@ func checkETag(w ResponseWriter, r *Request, modtime time.Time) (rangeReq string
 		}
 
 		// TODO(bradfitz): deal with comma-separated or multiple-valued
-		// list of If-None-match values.  For now just handle the common
+		// list of If-None-match values. For now just handle the common
 		// case of a single item.
 		if inm == etag || inm == "*" {
 			h := w.Header()
@@ -393,6 +393,15 @@ func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirec
 		}
 	}
 
+	// redirect if the directory name doesn't end in a slash
+	if d.IsDir() {
+		url := r.URL.Path
+		if url[len(url)-1] != '/' {
+			localRedirect(w, r, path.Base(url)+"/")
+			return
+		}
+	}
+
 	// use contents of index.html for directory, if present
 	if d.IsDir() {
 		index := strings.TrimSuffix(name, "/") + indexPage
@@ -451,7 +460,7 @@ func localRedirect(w ResponseWriter, r *Request, newPath string) {
 // ServeFile replies to the request with the contents of the named
 // file or directory.
 //
-// If the provided file or direcory name is a relative path, it is
+// If the provided file or directory name is a relative path, it is
 // interpreted relative to the current directory and may ascend to parent
 // directories. If the provided name is constructed from user input, it
 // should be sanitized before calling ServeFile. As a precaution, ServeFile
diff --git a/libgo/go/net/http/fs_test.go b/libgo/go/net/http/fs_test.go
index cf5b63c9f75..22be3899223 100644
--- a/libgo/go/net/http/fs_test.go
+++ b/libgo/go/net/http/fs_test.go
@@ -24,7 +24,6 @@ import (
 	"reflect"
 	"regexp"
 	"runtime"
-	"strconv"
 	"strings"
 	"testing"
 	"time"
@@ -39,8 +38,6 @@ type wantRange struct {
 	start, end int64 // range [start,end)
 }
 
-var itoa = strconv.Itoa
-
 var ServeFileRangeTests = []struct {
 	r      string
 	code   int
@@ -508,6 +505,24 @@ func TestServeFileFromCWD(t *testing.T) {
 	}
 }
 
+// Issue 13996
+func TestServeDirWithoutTrailingSlash(t *testing.T) {
+	e := "/testdata/"
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		ServeFile(w, r, ".")
+	}))
+	defer ts.Close()
+	r, err := Get(ts.URL + "/testdata")
+	if err != nil {
+		t.Fatal(err)
+	}
+	r.Body.Close()
+	if g := r.Request.URL.Path; g != e {
+		t.Errorf("got %s, want %s", g, e)
+	}
+}
+
 // Tests that ServeFile doesn't add a Content-Length if a Content-Encoding is
 // specified.
 func TestServeFileWithContentEncoding_h1(t *testing.T) { testServeFileWithContentEncoding(t, h1Mode) }
@@ -963,9 +978,9 @@ func TestLinuxSendfile(t *testing.T) {
 
 	syscalls := "sendfile,sendfile64"
 	switch runtime.GOARCH {
-	case "mips64", "mips64le", "alpha":
-		// mips64 strace doesn't support sendfile64 and will error out
-		// if we specify that with `-e trace='.
+	case "mips64", "mips64le", "s390x", "alpha":
+		// strace on the above platforms doesn't support sendfile64
+		// and will error out if we specify that with `-e trace='.
 		syscalls = "sendfile"
 	}
 
diff --git a/libgo/go/net/http/h2_bundle.go b/libgo/go/net/http/h2_bundle.go
index 4e19b3e71f7..db774554b2c 100644
--- a/libgo/go/net/http/h2_bundle.go
+++ b/libgo/go/net/http/h2_bundle.go
@@ -1,5 +1,5 @@
 // Code generated by golang.org/x/tools/cmd/bundle.
-//go:generate bundle -o h2_bundle.go -prefix http2 -import golang.org/x/net/http2/hpack=internal/golang.org/x/net/http2/hpack golang.org/x/net/http2
+//go:generate bundle -o h2_bundle.go -prefix http2 golang.org/x/net/http2
 
 // Package http2 implements the HTTP/2 protocol.
 //
@@ -20,15 +20,16 @@ import (
 	"bufio"
 	"bytes"
 	"compress/gzip"
+	"context"
 	"crypto/tls"
 	"encoding/binary"
 	"errors"
 	"fmt"
-	"internal/golang.org/x/net/http2/hpack"
 	"io"
 	"io/ioutil"
 	"log"
 	"net"
+	"net/http/httptrace"
 	"net/textproto"
 	"net/url"
 	"os"
@@ -39,6 +40,9 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"golang_org/x/net/http2/hpack"
+	"golang_org/x/net/lex/httplex"
 )
 
 // ClientConnPool manages a pool of HTTP/2 client connections.
@@ -47,6 +51,18 @@ type http2ClientConnPool interface {
 	MarkDead(*http2ClientConn)
 }
 
+// clientConnPoolIdleCloser is the interface implemented by ClientConnPool
+// implementations which can close their idle connections.
+type http2clientConnPoolIdleCloser interface {
+	http2ClientConnPool
+	closeIdleConnections()
+}
+
+var (
+	_ http2clientConnPoolIdleCloser = (*http2clientConnPool)(nil)
+	_ http2clientConnPoolIdleCloser = http2noDialClientConnPool{}
+)
+
 // TODO: use singleflight for dialing and addConnCalls?
 type http2clientConnPool struct {
 	t *http2Transport
@@ -247,6 +263,15 @@ func http2filterOutClientConn(in []*http2ClientConn, exclude *http2ClientConn) [
 	return out
 }
 
+// noDialClientConnPool is an implementation of http2.ClientConnPool
+// which never dials.  We let the HTTP/1.1 client dial and use its TLS
+// connection instead.
+type http2noDialClientConnPool struct{ *http2clientConnPool }
+
+func (p http2noDialClientConnPool) GetClientConn(req *Request, addr string) (*http2ClientConn, error) {
+	return p.getClientConn(req, addr, http2noDialOnMiss)
+}
+
 func http2configureTransport(t1 *Transport) (*http2Transport, error) {
 	connPool := new(http2clientConnPool)
 	t2 := &http2Transport{
@@ -267,7 +292,7 @@ func http2configureTransport(t1 *Transport) (*http2Transport, error) {
 		t1.TLSClientConfig.NextProtos = append(t1.TLSClientConfig.NextProtos, "http/1.1")
 	}
 	upgradeFn := func(authority string, c *tls.Conn) RoundTripper {
-		addr := http2authorityAddr(authority)
+		addr := http2authorityAddr("https", authority)
 		if used, err := connPool.addConnIfNeeded(addr, t2, c); err != nil {
 			go c.Close()
 			return http2erringRoundTripper{err}
@@ -299,15 +324,6 @@ func http2registerHTTPSProtocol(t *Transport, rt RoundTripper) (err error) {
 	return nil
 }
 
-// noDialClientConnPool is an implementation of http2.ClientConnPool
-// which never dials.  We let the HTTP/1.1 client dial and use its TLS
-// connection instead.
-type http2noDialClientConnPool struct{ *http2clientConnPool }
-
-func (p http2noDialClientConnPool) GetClientConn(req *Request, addr string) (*http2ClientConn, error) {
-	return p.getClientConn(req, addr, http2noDialOnMiss)
-}
-
 // noDialH2RoundTripper is a RoundTripper which only tries to complete the request
 // if there's already has a cached connection to the host.
 type http2noDialH2RoundTripper struct{ t *http2Transport }
@@ -403,6 +419,35 @@ func (e http2connError) Error() string {
 	return fmt.Sprintf("http2: connection error: %v: %v", e.Code, e.Reason)
 }
 
+type http2pseudoHeaderError string
+
+func (e http2pseudoHeaderError) Error() string {
+	return fmt.Sprintf("invalid pseudo-header %q", string(e))
+}
+
+type http2duplicatePseudoHeaderError string
+
+func (e http2duplicatePseudoHeaderError) Error() string {
+	return fmt.Sprintf("duplicate pseudo-header %q", string(e))
+}
+
+type http2headerFieldNameError string
+
+func (e http2headerFieldNameError) Error() string {
+	return fmt.Sprintf("invalid header field name %q", string(e))
+}
+
+type http2headerFieldValueError string
+
+func (e http2headerFieldValueError) Error() string {
+	return fmt.Sprintf("invalid header field value %q", string(e))
+}
+
+var (
+	http2errMixPseudoHeaderTypes = errors.New("mix of request and response pseudo headers")
+	http2errPseudoAfterRegular   = errors.New("pseudo header field after regular")
+)
+
 // fixedBuffer is an io.ReadWriter backed by a fixed size buffer.
 // It never allocates, but moves old data as new data is written.
 type http2fixedBuffer struct {
@@ -743,7 +788,7 @@ type http2Frame interface {
 type http2Framer struct {
 	r         io.Reader
 	lastFrame http2Frame
-	errReason string
+	errDetail error
 
 	// lastHeaderStream is non-zero if the last frame was an
 	// unfinished HEADERS/CONTINUATION.
@@ -775,14 +820,33 @@ type http2Framer struct {
 	// to return non-compliant frames or frame orders.
 	// This is for testing and permits using the Framer to test
 	// other HTTP/2 implementations' conformance to the spec.
+	// It is not compatible with ReadMetaHeaders.
 	AllowIllegalReads bool
 
+	// ReadMetaHeaders if non-nil causes ReadFrame to merge
+	// HEADERS and CONTINUATION frames together and return
+	// MetaHeadersFrame instead.
+	ReadMetaHeaders *hpack.Decoder
+
+	// MaxHeaderListSize is the http2 MAX_HEADER_LIST_SIZE.
+	// It's used only if ReadMetaHeaders is set; 0 means a sane default
+	// (currently 16MB)
+	// If the limit is hit, MetaHeadersFrame.Truncated is set true.
+	MaxHeaderListSize uint32
+
 	logReads bool
 
 	debugFramer    *http2Framer // only use for logging written writes
 	debugFramerBuf *bytes.Buffer
 }
 
+func (fr *http2Framer) maxHeaderListSize() uint32 {
+	if fr.MaxHeaderListSize == 0 {
+		return 16 << 20
+	}
+	return fr.MaxHeaderListSize
+}
+
 func (f *http2Framer) startWrite(ftype http2FrameType, flags http2Flags, streamID uint32) {
 
 	f.wbuf = append(f.wbuf[:0],
@@ -879,6 +943,17 @@ func (fr *http2Framer) SetMaxReadFrameSize(v uint32) {
 	fr.maxReadSize = v
 }
 
+// ErrorDetail returns a more detailed error of the last error
+// returned by Framer.ReadFrame. For instance, if ReadFrame
+// returns a StreamError with code PROTOCOL_ERROR, ErrorDetail
+// will say exactly what was invalid. ErrorDetail is not guaranteed
+// to return a non-nil value and like the rest of the http2 package,
+// its return value is not protected by an API compatibility promise.
+// ErrorDetail is reset after the next call to ReadFrame.
+func (fr *http2Framer) ErrorDetail() error {
+	return fr.errDetail
+}
+
 // ErrFrameTooLarge is returned from Framer.ReadFrame when the peer
 // sends a frame that is larger than declared with SetMaxReadFrameSize.
 var http2ErrFrameTooLarge = errors.New("http2: frame too large")
@@ -897,9 +972,10 @@ func http2terminalReadFrameError(err error) bool {
 //
 // If the frame is larger than previously set with SetMaxReadFrameSize, the
 // returned error is ErrFrameTooLarge. Other errors may be of type
-// ConnectionError, StreamError, or anything else from from the underlying
+// ConnectionError, StreamError, or anything else from the underlying
 // reader.
 func (fr *http2Framer) ReadFrame() (http2Frame, error) {
+	fr.errDetail = nil
 	if fr.lastFrame != nil {
 		fr.lastFrame.invalidate()
 	}
@@ -927,6 +1003,9 @@ func (fr *http2Framer) ReadFrame() (http2Frame, error) {
 	if fr.logReads {
 		log.Printf("http2: Framer %p: read %v", fr, http2summarizeFrame(f))
 	}
+	if fh.Type == http2FrameHeaders && fr.ReadMetaHeaders != nil {
+		return fr.readMetaFrame(f.(*http2HeadersFrame))
+	}
 	return f, nil
 }
 
@@ -935,7 +1014,7 @@ func (fr *http2Framer) ReadFrame() (http2Frame, error) {
 // to the peer before hanging up on them. This might help others debug
 // their implementations.
 func (fr *http2Framer) connError(code http2ErrCode, reason string) error {
-	fr.errReason = reason
+	fr.errDetail = errors.New(reason)
 	return http2ConnectionError(code)
 }
 
@@ -1023,7 +1102,14 @@ func http2parseDataFrame(fh http2FrameHeader, payload []byte) (http2Frame, error
 	return f, nil
 }
 
-var http2errStreamID = errors.New("invalid streamid")
+var (
+	http2errStreamID    = errors.New("invalid stream ID")
+	http2errDepStreamID = errors.New("invalid dependent stream ID")
+)
+
+func http2validStreamIDOrZero(streamID uint32) bool {
+	return streamID&(1<<31) == 0
+}
 
 func http2validStreamID(streamID uint32) bool {
 	return streamID != 0 && streamID&(1<<31) == 0
@@ -1389,8 +1475,8 @@ func (f *http2Framer) WriteHeaders(p http2HeadersFrameParam) error {
 	}
 	if !p.Priority.IsZero() {
 		v := p.Priority.StreamDep
-		if !http2validStreamID(v) && !f.AllowIllegalWrites {
-			return errors.New("invalid dependent stream id")
+		if !http2validStreamIDOrZero(v) && !f.AllowIllegalWrites {
+			return http2errDepStreamID
 		}
 		if p.Priority.Exclusive {
 			v |= 1 << 31
@@ -1458,6 +1544,9 @@ func (f *http2Framer) WritePriority(streamID uint32, p http2PriorityParam) error
 	if !http2validStreamID(streamID) && !f.AllowIllegalWrites {
 		return http2errStreamID
 	}
+	if !http2validStreamIDOrZero(p.StreamDep) {
+		return http2errDepStreamID
+	}
 	f.startWrite(http2FramePriority, 0, streamID)
 	v := p.StreamDep
 	if p.Exclusive {
@@ -1669,6 +1758,193 @@ type http2headersEnder interface {
 	HeadersEnded() bool
 }
 
+type http2headersOrContinuation interface {
+	http2headersEnder
+	HeaderBlockFragment() []byte
+}
+
+// A MetaHeadersFrame is the representation of one HEADERS frame and
+// zero or more contiguous CONTINUATION frames and the decoding of
+// their HPACK-encoded contents.
+//
+// This type of frame does not appear on the wire and is only returned
+// by the Framer when Framer.ReadMetaHeaders is set.
+type http2MetaHeadersFrame struct {
+	*http2HeadersFrame
+
+	// Fields are the fields contained in the HEADERS and
+	// CONTINUATION frames. The underlying slice is owned by the
+	// Framer and must not be retained after the next call to
+	// ReadFrame.
+	//
+	// Fields are guaranteed to be in the correct http2 order and
+	// not have unknown pseudo header fields or invalid header
+	// field names or values. Required pseudo header fields may be
+	// missing, however. Use the MetaHeadersFrame.Pseudo accessor
+	// method access pseudo headers.
+	Fields []hpack.HeaderField
+
+	// Truncated is whether the max header list size limit was hit
+	// and Fields is incomplete. The hpack decoder state is still
+	// valid, however.
+	Truncated bool
+}
+
+// PseudoValue returns the given pseudo header field's value.
+// The provided pseudo field should not contain the leading colon.
+func (mh *http2MetaHeadersFrame) PseudoValue(pseudo string) string {
+	for _, hf := range mh.Fields {
+		if !hf.IsPseudo() {
+			return ""
+		}
+		if hf.Name[1:] == pseudo {
+			return hf.Value
+		}
+	}
+	return ""
+}
+
+// RegularFields returns the regular (non-pseudo) header fields of mh.
+// The caller does not own the returned slice.
+func (mh *http2MetaHeadersFrame) RegularFields() []hpack.HeaderField {
+	for i, hf := range mh.Fields {
+		if !hf.IsPseudo() {
+			return mh.Fields[i:]
+		}
+	}
+	return nil
+}
+
+// PseudoFields returns the pseudo header fields of mh.
+// The caller does not own the returned slice.
+func (mh *http2MetaHeadersFrame) PseudoFields() []hpack.HeaderField {
+	for i, hf := range mh.Fields {
+		if !hf.IsPseudo() {
+			return mh.Fields[:i]
+		}
+	}
+	return mh.Fields
+}
+
+func (mh *http2MetaHeadersFrame) checkPseudos() error {
+	var isRequest, isResponse bool
+	pf := mh.PseudoFields()
+	for i, hf := range pf {
+		switch hf.Name {
+		case ":method", ":path", ":scheme", ":authority":
+			isRequest = true
+		case ":status":
+			isResponse = true
+		default:
+			return http2pseudoHeaderError(hf.Name)
+		}
+
+		for _, hf2 := range pf[:i] {
+			if hf.Name == hf2.Name {
+				return http2duplicatePseudoHeaderError(hf.Name)
+			}
+		}
+	}
+	if isRequest && isResponse {
+		return http2errMixPseudoHeaderTypes
+	}
+	return nil
+}
+
+func (fr *http2Framer) maxHeaderStringLen() int {
+	v := fr.maxHeaderListSize()
+	if uint32(int(v)) == v {
+		return int(v)
+	}
+
+	return 0
+}
+
+// readMetaFrame returns 0 or more CONTINUATION frames from fr and
+// merge them into into the provided hf and returns a MetaHeadersFrame
+// with the decoded hpack values.
+func (fr *http2Framer) readMetaFrame(hf *http2HeadersFrame) (*http2MetaHeadersFrame, error) {
+	if fr.AllowIllegalReads {
+		return nil, errors.New("illegal use of AllowIllegalReads with ReadMetaHeaders")
+	}
+	mh := &http2MetaHeadersFrame{
+		http2HeadersFrame: hf,
+	}
+	var remainSize = fr.maxHeaderListSize()
+	var sawRegular bool
+
+	var invalid error // pseudo header field errors
+	hdec := fr.ReadMetaHeaders
+	hdec.SetEmitEnabled(true)
+	hdec.SetMaxStringLength(fr.maxHeaderStringLen())
+	hdec.SetEmitFunc(func(hf hpack.HeaderField) {
+		if !httplex.ValidHeaderFieldValue(hf.Value) {
+			invalid = http2headerFieldValueError(hf.Value)
+		}
+		isPseudo := strings.HasPrefix(hf.Name, ":")
+		if isPseudo {
+			if sawRegular {
+				invalid = http2errPseudoAfterRegular
+			}
+		} else {
+			sawRegular = true
+			if !http2validWireHeaderFieldName(hf.Name) {
+				invalid = http2headerFieldNameError(hf.Name)
+			}
+		}
+
+		if invalid != nil {
+			hdec.SetEmitEnabled(false)
+			return
+		}
+
+		size := hf.Size()
+		if size > remainSize {
+			hdec.SetEmitEnabled(false)
+			mh.Truncated = true
+			return
+		}
+		remainSize -= size
+
+		mh.Fields = append(mh.Fields, hf)
+	})
+
+	defer hdec.SetEmitFunc(func(hf hpack.HeaderField) {})
+
+	var hc http2headersOrContinuation = hf
+	for {
+		frag := hc.HeaderBlockFragment()
+		if _, err := hdec.Write(frag); err != nil {
+			return nil, http2ConnectionError(http2ErrCodeCompression)
+		}
+
+		if hc.HeadersEnded() {
+			break
+		}
+		if f, err := fr.ReadFrame(); err != nil {
+			return nil, err
+		} else {
+			hc = f.(*http2ContinuationFrame)
+		}
+	}
+
+	mh.http2HeadersFrame.headerFragBuf = nil
+	mh.http2HeadersFrame.invalidate()
+
+	if err := hdec.Close(); err != nil {
+		return nil, http2ConnectionError(http2ErrCodeCompression)
+	}
+	if invalid != nil {
+		fr.errDetail = invalid
+		return nil, http2StreamError{mh.StreamID, http2ErrCodeProtocol}
+	}
+	if err := mh.checkPseudos(); err != nil {
+		fr.errDetail = err
+		return nil, http2StreamError{mh.StreamID, http2ErrCodeProtocol}
+	}
+	return mh, nil
+}
+
 func http2summarizeFrame(f http2Frame) string {
 	var buf bytes.Buffer
 	f.Header().writeDebug(&buf)
@@ -1712,7 +1988,111 @@ func http2summarizeFrame(f http2Frame) string {
 	return buf.String()
 }
 
-func http2requestCancel(req *Request) <-chan struct{} { return req.Cancel }
+func http2transportExpectContinueTimeout(t1 *Transport) time.Duration {
+	return t1.ExpectContinueTimeout
+}
+
+// isBadCipher reports whether the cipher is blacklisted by the HTTP/2 spec.
+func http2isBadCipher(cipher uint16) bool {
+	switch cipher {
+	case tls.TLS_RSA_WITH_RC4_128_SHA,
+		tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
+		tls.TLS_RSA_WITH_AES_128_CBC_SHA,
+		tls.TLS_RSA_WITH_AES_256_CBC_SHA,
+		tls.TLS_RSA_WITH_AES_128_GCM_SHA256,
+		tls.TLS_RSA_WITH_AES_256_GCM_SHA384,
+		tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
+		tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+		tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+		tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
+		tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+		tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+		tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:
+
+		return true
+	default:
+		return false
+	}
+}
+
+type http2contextContext interface {
+	context.Context
+}
+
+func http2serverConnBaseContext(c net.Conn, opts *http2ServeConnOpts) (ctx http2contextContext, cancel func()) {
+	ctx, cancel = context.WithCancel(context.Background())
+	ctx = context.WithValue(ctx, LocalAddrContextKey, c.LocalAddr())
+	if hs := opts.baseConfig(); hs != nil {
+		ctx = context.WithValue(ctx, ServerContextKey, hs)
+	}
+	return
+}
+
+func http2contextWithCancel(ctx http2contextContext) (_ http2contextContext, cancel func()) {
+	return context.WithCancel(ctx)
+}
+
+func http2requestWithContext(req *Request, ctx http2contextContext) *Request {
+	return req.WithContext(ctx)
+}
+
+type http2clientTrace httptrace.ClientTrace
+
+func http2reqContext(r *Request) context.Context { return r.Context() }
+
+func http2setResponseUncompressed(res *Response) { res.Uncompressed = true }
+
+func http2traceGotConn(req *Request, cc *http2ClientConn) {
+	trace := httptrace.ContextClientTrace(req.Context())
+	if trace == nil || trace.GotConn == nil {
+		return
+	}
+	ci := httptrace.GotConnInfo{Conn: cc.tconn}
+	cc.mu.Lock()
+	ci.Reused = cc.nextStreamID > 1
+	ci.WasIdle = len(cc.streams) == 0 && ci.Reused
+	if ci.WasIdle && !cc.lastActive.IsZero() {
+		ci.IdleTime = time.Now().Sub(cc.lastActive)
+	}
+	cc.mu.Unlock()
+
+	trace.GotConn(ci)
+}
+
+func http2traceWroteHeaders(trace *http2clientTrace) {
+	if trace != nil && trace.WroteHeaders != nil {
+		trace.WroteHeaders()
+	}
+}
+
+func http2traceGot100Continue(trace *http2clientTrace) {
+	if trace != nil && trace.Got100Continue != nil {
+		trace.Got100Continue()
+	}
+}
+
+func http2traceWait100Continue(trace *http2clientTrace) {
+	if trace != nil && trace.Wait100Continue != nil {
+		trace.Wait100Continue()
+	}
+}
+
+func http2traceWroteRequest(trace *http2clientTrace, err error) {
+	if trace != nil && trace.WroteRequest != nil {
+		trace.WroteRequest(httptrace.WroteRequestInfo{Err: err})
+	}
+}
+
+func http2traceFirstResponseByte(trace *http2clientTrace) {
+	if trace != nil && trace.GotFirstResponseByte != nil {
+		trace.GotFirstResponseByte()
+	}
+}
+
+func http2requestTrace(req *Request) *http2clientTrace {
+	trace := httptrace.ContextClientTrace(req.Context())
+	return (*http2clientTrace)(trace)
+}
 
 var http2DebugGoroutines = os.Getenv("DEBUG_HTTP2_GOROUTINES") == "1"
 
@@ -2070,57 +2450,23 @@ var (
 	http2errInvalidHeaderFieldValue = errors.New("http2: invalid header field value")
 )
 
-// validHeaderFieldName reports whether v is a valid header field name (key).
-//  RFC 7230 says:
-//   header-field   = field-name ":" OWS field-value OWS
-//   field-name     = token
-//   tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
-//           "^" / "_" / "
+// validWireHeaderFieldName reports whether v is a valid header field
+// name (key). See httplex.ValidHeaderName for the base rules.
+//
 // Further, http2 says:
 //   "Just as in HTTP/1.x, header field names are strings of ASCII
 //   characters that are compared in a case-insensitive
 //   fashion. However, header field names MUST be converted to
 //   lowercase prior to their encoding in HTTP/2. "
-func http2validHeaderFieldName(v string) bool {
+func http2validWireHeaderFieldName(v string) bool {
 	if len(v) == 0 {
 		return false
 	}
 	for _, r := range v {
-		if int(r) >= len(http2isTokenTable) || ('A' <= r && r <= 'Z') {
-			return false
-		}
-		if !http2isTokenTable[byte(r)] {
+		if !httplex.IsTokenRune(r) {
 			return false
 		}
-	}
-	return true
-}
-
-// validHeaderFieldValue reports whether v is a valid header field value.
-//
-// RFC 7230 says:
-//  field-value    = *( field-content / obs-fold )
-//  obj-fold       =  N/A to http2, and deprecated
-//  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]
-//  field-vchar    = VCHAR / obs-text
-//  obs-text       = %x80-FF
-//  VCHAR          = "any visible [USASCII] character"
-//
-// http2 further says: "Similarly, HTTP/2 allows header field values
-// that are not valid. While most of the values that can be encoded
-// will not alter header field parsing, carriage return (CR, ASCII
-// 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII
-// 0x0) might be exploited by an attacker if they are translated
-// verbatim. Any request or response that contains a character not
-// permitted in a header field value MUST be treated as malformed
-// (Section 8.1.2.6). Valid characters are defined by the
-// field-content ABNF rule in Section 3.2 of [RFC7230]."
-//
-// This function does not (yet?) properly handle the rejection of
-// strings that begin or end with SP or HTAB.
-func http2validHeaderFieldValue(v string) bool {
-	for i := 0; i < len(v); i++ {
-		if b := v[i]; b < ' ' && b != '\t' || b == 0x7f {
+		if 'A' <= r && r <= 'Z' {
 			return false
 		}
 	}
@@ -2225,7 +2571,7 @@ func http2mustUint31(v int32) uint32 {
 }
 
 // bodyAllowedForStatus reports whether a given response status code
-// permits a body. See RFC2616, section 4.4.
+// permits a body. See RFC 2616, section 4.4.
 func http2bodyAllowedForStatus(status int) bool {
 	switch {
 	case status >= 100 && status <= 199:
@@ -2251,90 +2597,44 @@ func (e *http2httpError) Temporary() bool { return true }
 
 var http2errTimeout error = &http2httpError{msg: "http2: timeout awaiting response headers", timeout: true}
 
-var http2isTokenTable = [127]bool{
-	'!':  true,
-	'#':  true,
-	'$':  true,
-	'%':  true,
-	'&':  true,
-	'\'': true,
-	'*':  true,
-	'+':  true,
-	'-':  true,
-	'.':  true,
-	'0':  true,
-	'1':  true,
-	'2':  true,
-	'3':  true,
-	'4':  true,
-	'5':  true,
-	'6':  true,
-	'7':  true,
-	'8':  true,
-	'9':  true,
-	'A':  true,
-	'B':  true,
-	'C':  true,
-	'D':  true,
-	'E':  true,
-	'F':  true,
-	'G':  true,
-	'H':  true,
-	'I':  true,
-	'J':  true,
-	'K':  true,
-	'L':  true,
-	'M':  true,
-	'N':  true,
-	'O':  true,
-	'P':  true,
-	'Q':  true,
-	'R':  true,
-	'S':  true,
-	'T':  true,
-	'U':  true,
-	'W':  true,
-	'V':  true,
-	'X':  true,
-	'Y':  true,
-	'Z':  true,
-	'^':  true,
-	'_':  true,
-	'`':  true,
-	'a':  true,
-	'b':  true,
-	'c':  true,
-	'd':  true,
-	'e':  true,
-	'f':  true,
-	'g':  true,
-	'h':  true,
-	'i':  true,
-	'j':  true,
-	'k':  true,
-	'l':  true,
-	'm':  true,
-	'n':  true,
-	'o':  true,
-	'p':  true,
-	'q':  true,
-	'r':  true,
-	's':  true,
-	't':  true,
-	'u':  true,
-	'v':  true,
-	'w':  true,
-	'x':  true,
-	'y':  true,
-	'z':  true,
-	'|':  true,
-	'~':  true,
-}
-
 type http2connectionStater interface {
 	ConnectionState() tls.ConnectionState
 }
 
+var http2sorterPool = sync.Pool{New: func() interface{} { return new(http2sorter) }}
+
+type http2sorter struct {
+	v []string // owned by sorter
+}
+
+func (s *http2sorter) Len() int { return len(s.v) }
+
+func (s *http2sorter) Swap(i, j int) { s.v[i], s.v[j] = s.v[j], s.v[i] }
+
+func (s *http2sorter) Less(i, j int) bool { return s.v[i] < s.v[j] }
+
+// Keys returns the sorted keys of h.
+//
+// The returned slice is only valid until s used again or returned to
+// its pool.
+func (s *http2sorter) Keys(h Header) []string {
+	keys := s.v[:0]
+	for k := range h {
+		keys = append(keys, k)
+	}
+	s.v = keys
+	sort.Sort(s)
+	return keys
+}
+
+func (s *http2sorter) SortStrings(ss []string) {
+
+	save := s.v
+	s.v = ss
+	sort.Sort(s)
+	s.v = save
+}
+
 // pipe is a goroutine-safe io.Reader/io.Writer pair.  It's like
 // io.Pipe except there are no PipeReader/PipeWriter halves, and the
 // underlying buffer is an interface. (io.Pipe is always unbuffered)
@@ -2354,6 +2654,12 @@ type http2pipeBuffer interface {
 	io.Reader
 }
 
+func (p *http2pipe) Len() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	return p.b.Len()
+}
+
 // Read waits until data is available and copies bytes
 // from the buffer into p.
 func (p *http2pipe) Read(d []byte) (n int, err error) {
@@ -2653,10 +2959,14 @@ func (o *http2ServeConnOpts) handler() Handler {
 //
 // The opts parameter is optional. If nil, default values are used.
 func (s *http2Server) ServeConn(c net.Conn, opts *http2ServeConnOpts) {
+	baseCtx, cancel := http2serverConnBaseContext(c, opts)
+	defer cancel()
+
 	sc := &http2serverConn{
 		srv:              s,
 		hs:               opts.baseConfig(),
 		conn:             c,
+		baseCtx:          baseCtx,
 		remoteAddrStr:    c.RemoteAddr().String(),
 		bw:               http2newBufferedWriter(c),
 		handler:          opts.handler(),
@@ -2675,13 +2985,14 @@ func (s *http2Server) ServeConn(c net.Conn, opts *http2ServeConnOpts) {
 		serveG:            http2newGoroutineLock(),
 		pushEnabled:       true,
 	}
+
 	sc.flow.add(http2initialWindowSize)
 	sc.inflow.add(http2initialWindowSize)
 	sc.hpackEncoder = hpack.NewEncoder(&sc.headerWriteBuf)
-	sc.hpackDecoder = hpack.NewDecoder(http2initialHeaderTableSize, nil)
-	sc.hpackDecoder.SetMaxStringLength(sc.maxHeaderStringLen())
 
 	fr := http2NewFramer(sc.bw, c)
+	fr.ReadMetaHeaders = hpack.NewDecoder(http2initialHeaderTableSize, nil)
+	fr.MaxHeaderListSize = sc.maxHeaderListSize()
 	fr.SetMaxReadFrameSize(s.maxReadFrameSize())
 	sc.framer = fr
 
@@ -2711,27 +3022,6 @@ func (s *http2Server) ServeConn(c net.Conn, opts *http2ServeConnOpts) {
 	sc.serve()
 }
 
-// isBadCipher reports whether the cipher is blacklisted by the HTTP/2 spec.
-func http2isBadCipher(cipher uint16) bool {
-	switch cipher {
-	case tls.TLS_RSA_WITH_RC4_128_SHA,
-		tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
-		tls.TLS_RSA_WITH_AES_128_CBC_SHA,
-		tls.TLS_RSA_WITH_AES_256_CBC_SHA,
-		tls.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
-		tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
-		tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
-		tls.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
-		tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
-		tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
-		tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA:
-
-		return true
-	default:
-		return false
-	}
-}
-
 func (sc *http2serverConn) rejectConn(err http2ErrCode, debug string) {
 	sc.vlogf("http2: server rejecting conn: %v, %s", err, debug)
 
@@ -2747,8 +3037,8 @@ type http2serverConn struct {
 	conn             net.Conn
 	bw               *http2bufferedWriter // writing to conn
 	handler          Handler
+	baseCtx          http2contextContext
 	framer           *http2Framer
-	hpackDecoder     *hpack.Decoder
 	doneServing      chan struct{}              // closed when serverConn.serve ends
 	readFrameCh      chan http2readFrameResult  // written by serverConn.readFrames
 	wantWriteFrameCh chan http2frameWriteMsg    // from handlers -> serve
@@ -2775,7 +3065,6 @@ type http2serverConn struct {
 	headerTableSize       uint32
 	peerMaxHeaderListSize uint32            // zero means unknown (default)
 	canonHeader           map[string]string // http2-lower-case -> Go-Canonical-Case
-	req                   http2requestParam // non-zero while reading request headers
 	writingFrame          bool              // started write goroutine but haven't heard back on wroteFrameCh
 	needsFrameFlush       bool              // last frame write wasn't a flush
 	writeSched            http2writeScheduler
@@ -2784,21 +3073,13 @@ type http2serverConn struct {
 	goAwayCode            http2ErrCode
 	shutdownTimerCh       <-chan time.Time // nil until used
 	shutdownTimer         *time.Timer      // nil until used
+	freeRequestBodyBuf    []byte           // if non-nil, a free initialWindowSize buffer for getRequestBodyBuf
 
 	// Owned by the writeFrameAsync goroutine:
 	headerWriteBuf bytes.Buffer
 	hpackEncoder   *hpack.Encoder
 }
 
-func (sc *http2serverConn) maxHeaderStringLen() int {
-	v := sc.maxHeaderListSize()
-	if uint32(int(v)) == v {
-		return int(v)
-	}
-
-	return 0
-}
-
 func (sc *http2serverConn) maxHeaderListSize() uint32 {
 	n := sc.hs.MaxHeaderBytes
 	if n <= 0 {
@@ -2811,21 +3092,6 @@ func (sc *http2serverConn) maxHeaderListSize() uint32 {
 	return uint32(n + typicalHeaders*perFieldOverhead)
 }
 
-// requestParam is the state of the next request, initialized over
-// potentially several frames HEADERS + zero or more CONTINUATION
-// frames.
-type http2requestParam struct {
-	// stream is non-nil if we're reading (HEADER or CONTINUATION)
-	// frames for a request (but not DATA).
-	stream            *http2stream
-	header            Header
-	method, path      string
-	scheme, authority string
-	sawRegularHeader  bool  // saw a non-pseudo header already
-	invalidHeader     bool  // an invalid header was seen
-	headerListSize    int64 // actually uint32, but easier math this way
-}
-
 // stream represents a stream. This is the minimal metadata needed by
 // the serve goroutine. Most of the actual stream state is owned by
 // the http.Handler's goroutine in the responseWriter. Because the
@@ -2835,10 +3101,12 @@ type http2requestParam struct {
 // responseWriter's state field.
 type http2stream struct {
 	// immutable:
-	sc   *http2serverConn
-	id   uint32
-	body *http2pipe       // non-nil if expecting DATA frames
-	cw   http2closeWaiter // closed wait stream transitions to closed state
+	sc        *http2serverConn
+	id        uint32
+	body      *http2pipe       // non-nil if expecting DATA frames
+	cw        http2closeWaiter // closed wait stream transitions to closed state
+	ctx       http2contextContext
+	cancelCtx func()
 
 	// owned by serverConn's serve loop:
 	bodyBytes        int64        // body bytes seen so far
@@ -2852,6 +3120,8 @@ type http2stream struct {
 	sentReset        bool // only true once detached from streams map
 	gotReset         bool // only true once detacted from streams map
 	gotTrailerHeader bool // HEADER frame for trailers was seen
+	wroteHeaders     bool // whether we wrote headers (not status 100)
+	reqBuf           []byte
 
 	trailer    Header // accumulated trailers
 	reqTrailer Header // handler's Request.Trailer
@@ -2952,83 +3222,6 @@ func (sc *http2serverConn) condlogf(err error, format string, args ...interface{
 	}
 }
 
-func (sc *http2serverConn) onNewHeaderField(f hpack.HeaderField) {
-	sc.serveG.check()
-	if http2VerboseLogs {
-		sc.vlogf("http2: server decoded %v", f)
-	}
-	switch {
-	case !http2validHeaderFieldValue(f.Value):
-		sc.req.invalidHeader = true
-	case strings.HasPrefix(f.Name, ":"):
-		if sc.req.sawRegularHeader {
-			sc.logf("pseudo-header after regular header")
-			sc.req.invalidHeader = true
-			return
-		}
-		var dst *string
-		switch f.Name {
-		case ":method":
-			dst = &sc.req.method
-		case ":path":
-			dst = &sc.req.path
-		case ":scheme":
-			dst = &sc.req.scheme
-		case ":authority":
-			dst = &sc.req.authority
-		default:
-
-			sc.logf("invalid pseudo-header %q", f.Name)
-			sc.req.invalidHeader = true
-			return
-		}
-		if *dst != "" {
-			sc.logf("duplicate pseudo-header %q sent", f.Name)
-			sc.req.invalidHeader = true
-			return
-		}
-		*dst = f.Value
-	case !http2validHeaderFieldName(f.Name):
-		sc.req.invalidHeader = true
-	default:
-		sc.req.sawRegularHeader = true
-		sc.req.header.Add(sc.canonicalHeader(f.Name), f.Value)
-		const headerFieldOverhead = 32 // per spec
-		sc.req.headerListSize += int64(len(f.Name)) + int64(len(f.Value)) + headerFieldOverhead
-		if sc.req.headerListSize > int64(sc.maxHeaderListSize()) {
-			sc.hpackDecoder.SetEmitEnabled(false)
-		}
-	}
-}
-
-func (st *http2stream) onNewTrailerField(f hpack.HeaderField) {
-	sc := st.sc
-	sc.serveG.check()
-	if http2VerboseLogs {
-		sc.vlogf("http2: server decoded trailer %v", f)
-	}
-	switch {
-	case strings.HasPrefix(f.Name, ":"):
-		sc.req.invalidHeader = true
-		return
-	case !http2validHeaderFieldName(f.Name) || !http2validHeaderFieldValue(f.Value):
-		sc.req.invalidHeader = true
-		return
-	default:
-		key := sc.canonicalHeader(f.Name)
-		if st.trailer != nil {
-			vv := append(st.trailer[key], f.Value)
-			st.trailer[key] = vv
-
-			// arbitrary; TODO: read spec about header list size limits wrt trailers
-			const tooBig = 1000
-			if len(vv) >= tooBig {
-				sc.hpackDecoder.SetEmitEnabled(false)
-			}
-		}
-	}
-}
-
 func (sc *http2serverConn) canonicalHeader(v string) string {
 	sc.serveG.check()
 	cv, ok := http2commonCanonHeader[v]
@@ -3063,10 +3256,11 @@ type http2readFrameResult struct {
 // It's run on its own goroutine.
 func (sc *http2serverConn) readFrames() {
 	gate := make(http2gate)
+	gateDone := gate.Done
 	for {
 		f, err := sc.framer.ReadFrame()
 		select {
-		case sc.readFrameCh <- http2readFrameResult{f, err, gate.Done}:
+		case sc.readFrameCh <- http2readFrameResult{f, err, gateDone}:
 		case <-sc.doneServing:
 			return
 		}
@@ -3290,7 +3484,21 @@ func (sc *http2serverConn) writeFrameFromHandler(wm http2frameWriteMsg) error {
 // If you're not on the serve goroutine, use writeFrameFromHandler instead.
 func (sc *http2serverConn) writeFrame(wm http2frameWriteMsg) {
 	sc.serveG.check()
-	sc.writeSched.add(wm)
+
+	var ignoreWrite bool
+
+	switch wm.write.(type) {
+	case *http2writeResHeaders:
+		wm.stream.wroteHeaders = true
+	case http2write100ContinueHeadersFrame:
+		if wm.stream.wroteHeaders {
+			ignoreWrite = true
+		}
+	}
+
+	if !ignoreWrite {
+		sc.writeSched.add(wm)
+	}
 	sc.scheduleFrameWrite()
 }
 
@@ -3511,10 +3719,8 @@ func (sc *http2serverConn) processFrame(f http2Frame) error {
 	switch f := f.(type) {
 	case *http2SettingsFrame:
 		return sc.processSettings(f)
-	case *http2HeadersFrame:
+	case *http2MetaHeadersFrame:
 		return sc.processHeaders(f)
-	case *http2ContinuationFrame:
-		return sc.processContinuation(f)
 	case *http2WindowUpdateFrame:
 		return sc.processWindowUpdate(f)
 	case *http2PingFrame:
@@ -3579,6 +3785,7 @@ func (sc *http2serverConn) processResetStream(f *http2RSTStreamFrame) error {
 	}
 	if st != nil {
 		st.gotReset = true
+		st.cancelCtx()
 		sc.closeStream(st, http2StreamError{f.StreamID, f.ErrCode})
 	}
 	return nil
@@ -3600,6 +3807,10 @@ func (sc *http2serverConn) closeStream(st *http2stream, err error) {
 	}
 	st.cw.Close()
 	sc.writeSched.forgetStream(st.id)
+	if st.reqBuf != nil {
+
+		sc.freeRequestBodyBuf = st.reqBuf
+	}
 }
 
 func (sc *http2serverConn) processSettings(f *http2SettingsFrame) error {
@@ -3732,7 +3943,7 @@ func (st *http2stream) copyTrailersToHandlerRequest() {
 	}
 }
 
-func (sc *http2serverConn) processHeaders(f *http2HeadersFrame) error {
+func (sc *http2serverConn) processHeaders(f *http2MetaHeadersFrame) error {
 	sc.serveG.check()
 	id := f.Header().StreamID
 	if sc.inGoAway {
@@ -3749,17 +3960,18 @@ func (sc *http2serverConn) processHeaders(f *http2HeadersFrame) error {
 		return st.processTrailerHeaders(f)
 	}
 
-	if id <= sc.maxStreamID || sc.req.stream != nil {
+	if id <= sc.maxStreamID {
 		return http2ConnectionError(http2ErrCodeProtocol)
 	}
+	sc.maxStreamID = id
 
-	if id > sc.maxStreamID {
-		sc.maxStreamID = id
-	}
+	ctx, cancelCtx := http2contextWithCancel(sc.baseCtx)
 	st = &http2stream{
-		sc:    sc,
-		id:    id,
-		state: http2stateOpen,
+		sc:        sc,
+		id:        id,
+		state:     http2stateOpen,
+		ctx:       ctx,
+		cancelCtx: cancelCtx,
 	}
 	if f.StreamEnded() {
 		st.state = http2stateHalfClosedRemote
@@ -3779,50 +3991,6 @@ func (sc *http2serverConn) processHeaders(f *http2HeadersFrame) error {
 	if sc.curOpenStreams == 1 {
 		sc.setConnState(StateActive)
 	}
-	sc.req = http2requestParam{
-		stream: st,
-		header: make(Header),
-	}
-	sc.hpackDecoder.SetEmitFunc(sc.onNewHeaderField)
-	sc.hpackDecoder.SetEmitEnabled(true)
-	return sc.processHeaderBlockFragment(st, f.HeaderBlockFragment(), f.HeadersEnded())
-}
-
-func (st *http2stream) processTrailerHeaders(f *http2HeadersFrame) error {
-	sc := st.sc
-	sc.serveG.check()
-	if st.gotTrailerHeader {
-		return http2ConnectionError(http2ErrCodeProtocol)
-	}
-	st.gotTrailerHeader = true
-	if !f.StreamEnded() {
-		return http2StreamError{st.id, http2ErrCodeProtocol}
-	}
-	sc.resetPendingRequest()
-	return st.processTrailerHeaderBlockFragment(f.HeaderBlockFragment(), f.HeadersEnded())
-}
-
-func (sc *http2serverConn) processContinuation(f *http2ContinuationFrame) error {
-	sc.serveG.check()
-	st := sc.streams[f.Header().StreamID]
-	if st.gotTrailerHeader {
-		return st.processTrailerHeaderBlockFragment(f.HeaderBlockFragment(), f.HeadersEnded())
-	}
-	return sc.processHeaderBlockFragment(st, f.HeaderBlockFragment(), f.HeadersEnded())
-}
-
-func (sc *http2serverConn) processHeaderBlockFragment(st *http2stream, frag []byte, end bool) error {
-	sc.serveG.check()
-	if _, err := sc.hpackDecoder.Write(frag); err != nil {
-		return http2ConnectionError(http2ErrCodeCompression)
-	}
-	if !end {
-		return nil
-	}
-	if err := sc.hpackDecoder.Close(); err != nil {
-		return http2ConnectionError(http2ErrCodeCompression)
-	}
-	defer sc.resetPendingRequest()
 	if sc.curOpenStreams > sc.advMaxStreams {
 
 		if sc.unackedSettings == 0 {
@@ -3833,7 +4001,7 @@ func (sc *http2serverConn) processHeaderBlockFragment(st *http2stream, frag []by
 		return http2StreamError{st.id, http2ErrCodeRefusedStream}
 	}
 
-	rw, req, err := sc.newWriterAndRequest()
+	rw, req, err := sc.newWriterAndRequest(st, f)
 	if err != nil {
 		return err
 	}
@@ -3845,36 +4013,42 @@ func (sc *http2serverConn) processHeaderBlockFragment(st *http2stream, frag []by
 	st.declBodyBytes = req.ContentLength
 
 	handler := sc.handler.ServeHTTP
-	if !sc.hpackDecoder.EmitEnabled() {
+	if f.Truncated {
 
 		handler = http2handleHeaderListTooLong
+	} else if err := http2checkValidHTTP2Request(req); err != nil {
+		handler = http2new400Handler(err)
 	}
 
 	go sc.runHandler(rw, req, handler)
 	return nil
 }
 
-func (st *http2stream) processTrailerHeaderBlockFragment(frag []byte, end bool) error {
+func (st *http2stream) processTrailerHeaders(f *http2MetaHeadersFrame) error {
 	sc := st.sc
 	sc.serveG.check()
-	sc.hpackDecoder.SetEmitFunc(st.onNewTrailerField)
-	if _, err := sc.hpackDecoder.Write(frag); err != nil {
-		return http2ConnectionError(http2ErrCodeCompression)
+	if st.gotTrailerHeader {
+		return http2ConnectionError(http2ErrCodeProtocol)
 	}
-	if !end {
-		return nil
+	st.gotTrailerHeader = true
+	if !f.StreamEnded() {
+		return http2StreamError{st.id, http2ErrCodeProtocol}
 	}
 
-	rp := &sc.req
-	if rp.invalidHeader {
-		return http2StreamError{rp.stream.id, http2ErrCodeProtocol}
+	if len(f.PseudoFields()) > 0 {
+		return http2StreamError{st.id, http2ErrCodeProtocol}
 	}
+	if st.trailer != nil {
+		for _, hf := range f.RegularFields() {
+			key := sc.canonicalHeader(hf.Name)
+			if !http2ValidTrailerHeader(key) {
 
-	err := sc.hpackDecoder.Close()
-	st.endStream()
-	if err != nil {
-		return http2ConnectionError(http2ErrCodeCompression)
+				return http2StreamError{st.id, http2ErrCodeProtocol}
+			}
+			st.trailer[key] = append(st.trailer[key], hf.Value)
+		}
 	}
+	st.endStream()
 	return nil
 }
 
@@ -3912,59 +4086,56 @@ func http2adjustStreamPriority(streams map[uint32]*http2stream, streamID uint32,
 	}
 }
 
-// resetPendingRequest zeros out all state related to a HEADERS frame
-// and its zero or more CONTINUATION frames sent to start a new
-// request.
-func (sc *http2serverConn) resetPendingRequest() {
+func (sc *http2serverConn) newWriterAndRequest(st *http2stream, f *http2MetaHeadersFrame) (*http2responseWriter, *Request, error) {
 	sc.serveG.check()
-	sc.req = http2requestParam{}
-}
 
-func (sc *http2serverConn) newWriterAndRequest() (*http2responseWriter, *Request, error) {
-	sc.serveG.check()
-	rp := &sc.req
-
-	if rp.invalidHeader {
-		return nil, nil, http2StreamError{rp.stream.id, http2ErrCodeProtocol}
-	}
+	method := f.PseudoValue("method")
+	path := f.PseudoValue("path")
+	scheme := f.PseudoValue("scheme")
+	authority := f.PseudoValue("authority")
 
-	isConnect := rp.method == "CONNECT"
+	isConnect := method == "CONNECT"
 	if isConnect {
-		if rp.path != "" || rp.scheme != "" || rp.authority == "" {
-			return nil, nil, http2StreamError{rp.stream.id, http2ErrCodeProtocol}
+		if path != "" || scheme != "" || authority == "" {
+			return nil, nil, http2StreamError{f.StreamID, http2ErrCodeProtocol}
 		}
-	} else if rp.method == "" || rp.path == "" ||
-		(rp.scheme != "https" && rp.scheme != "http") {
+	} else if method == "" || path == "" ||
+		(scheme != "https" && scheme != "http") {
 
-		return nil, nil, http2StreamError{rp.stream.id, http2ErrCodeProtocol}
+		return nil, nil, http2StreamError{f.StreamID, http2ErrCodeProtocol}
 	}
 
-	bodyOpen := rp.stream.state == http2stateOpen
-	if rp.method == "HEAD" && bodyOpen {
+	bodyOpen := !f.StreamEnded()
+	if method == "HEAD" && bodyOpen {
 
-		return nil, nil, http2StreamError{rp.stream.id, http2ErrCodeProtocol}
+		return nil, nil, http2StreamError{f.StreamID, http2ErrCodeProtocol}
 	}
 	var tlsState *tls.ConnectionState // nil if not scheme https
 
-	if rp.scheme == "https" {
+	if scheme == "https" {
 		tlsState = sc.tlsState
 	}
-	authority := rp.authority
+
+	header := make(Header)
+	for _, hf := range f.RegularFields() {
+		header.Add(sc.canonicalHeader(hf.Name), hf.Value)
+	}
+
 	if authority == "" {
-		authority = rp.header.Get("Host")
+		authority = header.Get("Host")
 	}
-	needsContinue := rp.header.Get("Expect") == "100-continue"
+	needsContinue := header.Get("Expect") == "100-continue"
 	if needsContinue {
-		rp.header.Del("Expect")
+		header.Del("Expect")
 	}
 
-	if cookies := rp.header["Cookie"]; len(cookies) > 1 {
-		rp.header.Set("Cookie", strings.Join(cookies, "; "))
+	if cookies := header["Cookie"]; len(cookies) > 1 {
+		header.Set("Cookie", strings.Join(cookies, "; "))
 	}
 
 	// Setup Trailers
 	var trailer Header
-	for _, v := range rp.header["Trailer"] {
+	for _, v := range header["Trailer"] {
 		for _, key := range strings.Split(v, ",") {
 			key = CanonicalHeaderKey(strings.TrimSpace(key))
 			switch key {
@@ -3978,31 +4149,31 @@ func (sc *http2serverConn) newWriterAndRequest() (*http2responseWriter, *Request
 			}
 		}
 	}
-	delete(rp.header, "Trailer")
+	delete(header, "Trailer")
 
 	body := &http2requestBody{
 		conn:          sc,
-		stream:        rp.stream,
+		stream:        st,
 		needsContinue: needsContinue,
 	}
 	var url_ *url.URL
 	var requestURI string
 	if isConnect {
-		url_ = &url.URL{Host: rp.authority}
-		requestURI = rp.authority
+		url_ = &url.URL{Host: authority}
+		requestURI = authority
 	} else {
 		var err error
-		url_, err = url.ParseRequestURI(rp.path)
+		url_, err = url.ParseRequestURI(path)
 		if err != nil {
-			return nil, nil, http2StreamError{rp.stream.id, http2ErrCodeProtocol}
+			return nil, nil, http2StreamError{f.StreamID, http2ErrCodeProtocol}
 		}
-		requestURI = rp.path
+		requestURI = path
 	}
 	req := &Request{
-		Method:     rp.method,
+		Method:     method,
 		URL:        url_,
 		RemoteAddr: sc.remoteAddrStr,
-		Header:     rp.header,
+		Header:     header,
 		RequestURI: requestURI,
 		Proto:      "HTTP/2.0",
 		ProtoMajor: 2,
@@ -4012,12 +4183,16 @@ func (sc *http2serverConn) newWriterAndRequest() (*http2responseWriter, *Request
 		Body:       body,
 		Trailer:    trailer,
 	}
+	req = http2requestWithContext(req, st.ctx)
 	if bodyOpen {
+
+		buf := make([]byte, http2initialWindowSize)
+
 		body.pipe = &http2pipe{
-			b: &http2fixedBuffer{buf: make([]byte, http2initialWindowSize)},
+			b: &http2fixedBuffer{buf: buf},
 		}
 
-		if vv, ok := rp.header["Content-Length"]; ok {
+		if vv, ok := header["Content-Length"]; ok {
 			req.ContentLength, _ = strconv.ParseInt(vv[0], 10, 64)
 		} else {
 			req.ContentLength = -1
@@ -4030,7 +4205,7 @@ func (sc *http2serverConn) newWriterAndRequest() (*http2responseWriter, *Request
 	rws.conn = sc
 	rws.bw = bwSave
 	rws.bw.Reset(http2chunkWriter{rws})
-	rws.stream = rp.stream
+	rws.stream = st
 	rws.req = req
 	rws.body = body
 
@@ -4038,10 +4213,20 @@ func (sc *http2serverConn) newWriterAndRequest() (*http2responseWriter, *Request
 	return rw, req, nil
 }
 
+func (sc *http2serverConn) getRequestBodyBuf() []byte {
+	sc.serveG.check()
+	if buf := sc.freeRequestBodyBuf; buf != nil {
+		sc.freeRequestBodyBuf = nil
+		return buf
+	}
+	return make([]byte, http2initialWindowSize)
+}
+
 // Run on its own goroutine.
 func (sc *http2serverConn) runHandler(rw *http2responseWriter, req *Request, handler func(ResponseWriter, *Request)) {
 	didPanic := true
 	defer func() {
+		rw.rws.stream.cancelCtx()
 		if didPanic {
 			e := recover()
 			// Same as net/http:
@@ -4190,7 +4375,7 @@ type http2requestBody struct {
 
 func (b *http2requestBody) Close() error {
 	if b.pipe != nil {
-		b.pipe.CloseWithError(http2errClosedBody)
+		b.pipe.BreakWithError(http2errClosedBody)
 	}
 	b.closed = true
 	return nil
@@ -4265,9 +4450,9 @@ func (rws *http2responseWriterState) hasTrailers() bool { return len(rws.trailer
 // written in the trailers at the end of the response.
 func (rws *http2responseWriterState) declareTrailer(k string) {
 	k = CanonicalHeaderKey(k)
-	switch k {
-	case "Transfer-Encoding", "Content-Length", "Trailer":
+	if !http2ValidTrailerHeader(k) {
 
+		rws.conn.logf("ignoring invalid trailer %q", k)
 		return
 	}
 	if !http2strSliceContains(rws.trailers, k) {
@@ -4408,7 +4593,12 @@ func (rws *http2responseWriterState) promoteUndeclaredTrailers() {
 		rws.declareTrailer(trailerKey)
 		rws.handlerHeader[CanonicalHeaderKey(trailerKey)] = vv
 	}
-	sort.Strings(rws.trailers)
+
+	if len(rws.trailers) > 1 {
+		sorter := http2sorterPool.Get().(*http2sorter)
+		sorter.SortStrings(rws.trailers)
+		http2sorterPool.Put(sorter)
+	}
 }
 
 func (w *http2responseWriter) Flush() {
@@ -4552,6 +4742,72 @@ func http2foreachHeaderElement(v string, fn func(string)) {
 	}
 }
 
+// From http://httpwg.org/specs/rfc7540.html#rfc.section.8.1.2.2
+var http2connHeaders = []string{
+	"Connection",
+	"Keep-Alive",
+	"Proxy-Connection",
+	"Transfer-Encoding",
+	"Upgrade",
+}
+
+// checkValidHTTP2Request checks whether req is a valid HTTP/2 request,
+// per RFC 7540 Section 8.1.2.2.
+// The returned error is reported to users.
+func http2checkValidHTTP2Request(req *Request) error {
+	for _, h := range http2connHeaders {
+		if _, ok := req.Header[h]; ok {
+			return fmt.Errorf("request header %q is not valid in HTTP/2", h)
+		}
+	}
+	te := req.Header["Te"]
+	if len(te) > 0 && (len(te) > 1 || (te[0] != "trailers" && te[0] != "")) {
+		return errors.New(`request header "TE" may only be "trailers" in HTTP/2`)
+	}
+	return nil
+}
+
+func http2new400Handler(err error) HandlerFunc {
+	return func(w ResponseWriter, r *Request) {
+		Error(w, err.Error(), StatusBadRequest)
+	}
+}
+
+// ValidTrailerHeader reports whether name is a valid header field name to appear
+// in trailers.
+// See: http://tools.ietf.org/html/rfc7230#section-4.1.2
+func http2ValidTrailerHeader(name string) bool {
+	name = CanonicalHeaderKey(name)
+	if strings.HasPrefix(name, "If-") || http2badTrailer[name] {
+		return false
+	}
+	return true
+}
+
+var http2badTrailer = map[string]bool{
+	"Authorization":       true,
+	"Cache-Control":       true,
+	"Connection":          true,
+	"Content-Encoding":    true,
+	"Content-Length":      true,
+	"Content-Range":       true,
+	"Content-Type":        true,
+	"Expect":              true,
+	"Host":                true,
+	"Keep-Alive":          true,
+	"Max-Forwards":        true,
+	"Pragma":              true,
+	"Proxy-Authenticate":  true,
+	"Proxy-Authorization": true,
+	"Proxy-Connection":    true,
+	"Range":               true,
+	"Realm":               true,
+	"Te":                  true,
+	"Trailer":             true,
+	"Transfer-Encoding":   true,
+	"Www-Authenticate":    true,
+}
+
 const (
 	// transportDefaultConnFlow is how many connection-level flow control
 	// tokens we give the server at start-up, past the default 64k.
@@ -4601,6 +4857,10 @@ type http2Transport struct {
 	// uncompressed.
 	DisableCompression bool
 
+	// AllowHTTP, if true, permits HTTP/2 requests using the insecure,
+	// plain-text "http" scheme. Note that this does not enable h2c support.
+	AllowHTTP bool
+
 	// MaxHeaderListSize is the http2 SETTINGS_MAX_HEADER_LIST_SIZE to
 	// send in the initial settings frame. It is how many bytes
 	// of response headers are allow. Unlike the http2 spec, zero here
@@ -4673,11 +4933,14 @@ type http2ClientConn struct {
 	inflow       http2flow  // peer's conn-level flow control
 	closed       bool
 	goAway       *http2GoAwayFrame             // if non-nil, the GoAwayFrame we received
+	goAwayDebug  string                        // goAway frame's debug data, retained as a string
 	streams      map[uint32]*http2clientStream // client-initiated
 	nextStreamID uint32
 	bw           *bufio.Writer
 	br           *bufio.Reader
 	fr           *http2Framer
+	lastActive   time.Time
+
 	// Settings from peer:
 	maxFrameSize         uint32
 	maxConcurrentStreams uint32
@@ -4695,10 +4958,12 @@ type http2ClientConn struct {
 type http2clientStream struct {
 	cc            *http2ClientConn
 	req           *Request
+	trace         *http2clientTrace // or nil
 	ID            uint32
 	resc          chan http2resAndError
 	bufPipe       http2pipe // buffered pipe with the flow-controlled response payload
 	requestedGzip bool
+	on100         func() // optional code to run if get a 100 continue response
 
 	flow        http2flow // guarded by cc.mu
 	inflow      http2flow // guarded by cc.mu
@@ -4712,36 +4977,43 @@ type http2clientStream struct {
 	done chan struct{} // closed when stream remove from cc.streams map; close calls guarded by cc.mu
 
 	// owned by clientConnReadLoop:
-	pastHeaders  bool // got HEADERS w/ END_HEADERS
-	pastTrailers bool // got second HEADERS frame w/ END_HEADERS
+	firstByte    bool // got the first response byte
+	pastHeaders  bool // got first MetaHeadersFrame (actual headers)
+	pastTrailers bool // got optional second MetaHeadersFrame (trailers)
 
 	trailer    Header  // accumulated trailers
 	resTrailer *Header // client's Response.Trailer
 }
 
 // awaitRequestCancel runs in its own goroutine and waits for the user
-// to either cancel a RoundTrip request (using the provided
-// Request.Cancel channel), or for the request to be done (any way it
-// might be removed from the cc.streams map: peer reset, successful
-// completion, TCP connection breakage, etc)
-func (cs *http2clientStream) awaitRequestCancel(cancel <-chan struct{}) {
-	if cancel == nil {
+// to cancel a RoundTrip request, its context to expire, or for the
+// request to be done (any way it might be removed from the cc.streams
+// map: peer reset, successful completion, TCP connection breakage,
+// etc)
+func (cs *http2clientStream) awaitRequestCancel(req *Request) {
+	ctx := http2reqContext(req)
+	if req.Cancel == nil && ctx.Done() == nil {
 		return
 	}
 	select {
-	case <-cancel:
+	case <-req.Cancel:
 		cs.bufPipe.CloseWithError(http2errRequestCanceled)
 		cs.cc.writeStreamReset(cs.ID, http2ErrCodeCancel, nil)
+	case <-ctx.Done():
+		cs.bufPipe.CloseWithError(ctx.Err())
+		cs.cc.writeStreamReset(cs.ID, http2ErrCodeCancel, nil)
 	case <-cs.done:
 	}
 }
 
-// checkReset reports any error sent in a RST_STREAM frame by the
-// server.
-func (cs *http2clientStream) checkReset() error {
+// checkResetOrDone reports any error sent in a RST_STREAM frame by the
+// server, or errStreamClosed if the stream is complete.
+func (cs *http2clientStream) checkResetOrDone() error {
 	select {
 	case <-cs.peerReset:
 		return cs.resetErr
+	case <-cs.done:
+		return http2errStreamClosed
 	default:
 		return nil
 	}
@@ -4789,26 +5061,31 @@ func (t *http2Transport) RoundTrip(req *Request) (*Response, error) {
 
 // authorityAddr returns a given authority (a host/IP, or host:port / ip:port)
 // and returns a host:port. The port 443 is added if needed.
-func http2authorityAddr(authority string) (addr string) {
+func http2authorityAddr(scheme string, authority string) (addr string) {
 	if _, _, err := net.SplitHostPort(authority); err == nil {
 		return authority
 	}
-	return net.JoinHostPort(authority, "443")
+	port := "443"
+	if scheme == "http" {
+		port = "80"
+	}
+	return net.JoinHostPort(authority, port)
 }
 
 // RoundTripOpt is like RoundTrip, but takes options.
 func (t *http2Transport) RoundTripOpt(req *Request, opt http2RoundTripOpt) (*Response, error) {
-	if req.URL.Scheme != "https" {
+	if !(req.URL.Scheme == "https" || (req.URL.Scheme == "http" && t.AllowHTTP)) {
 		return nil, errors.New("http2: unsupported scheme")
 	}
 
-	addr := http2authorityAddr(req.URL.Host)
+	addr := http2authorityAddr(req.URL.Scheme, req.URL.Host)
 	for {
 		cc, err := t.connPool().GetClientConn(req, addr)
 		if err != nil {
 			t.vlogf("http2: Transport failed to get client conn for %s: %v", addr, err)
 			return nil, err
 		}
+		http2traceGotConn(req, cc)
 		res, err := cc.RoundTrip(req)
 		if http2shouldRetryRequest(req, err) {
 			continue
@@ -4825,7 +5102,7 @@ func (t *http2Transport) RoundTripOpt(req *Request, opt http2RoundTripOpt) (*Res
 // connected from previous requests but are now sitting idle.
 // It does not interrupt any connections currently in use.
 func (t *http2Transport) CloseIdleConnections() {
-	if cp, ok := t.connPool().(*http2clientConnPool); ok {
+	if cp, ok := t.connPool().(http2clientConnPoolIdleCloser); ok {
 		cp.closeIdleConnections()
 	}
 }
@@ -4857,8 +5134,12 @@ func (t *http2Transport) newTLSConfig(host string) *tls.Config {
 	if t.TLSClientConfig != nil {
 		*cfg = *t.TLSClientConfig
 	}
-	cfg.NextProtos = []string{http2NextProtoTLS}
-	cfg.ServerName = host
+	if !http2strSliceContains(cfg.NextProtos, http2NextProtoTLS) {
+		cfg.NextProtos = append([]string{http2NextProtoTLS}, cfg.NextProtos...)
+	}
+	if cfg.ServerName == "" {
+		cfg.ServerName = host
+	}
 	return cfg
 }
 
@@ -4898,6 +5179,13 @@ func (t *http2Transport) disableKeepAlives() bool {
 	return t.t1 != nil && t.t1.DisableKeepAlives
 }
 
+func (t *http2Transport) expectContinueTimeout() time.Duration {
+	if t.t1 == nil {
+		return 0
+	}
+	return http2transportExpectContinueTimeout(t.t1)
+}
+
 func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
 	if http2VerboseLogs {
 		t.vlogf("http2: Transport creating client conn to %v", c.RemoteAddr())
@@ -4923,6 +5211,8 @@ func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
 	cc.bw = bufio.NewWriter(http2stickyErrWriter{c, &cc.werr})
 	cc.br = bufio.NewReader(c)
 	cc.fr = http2NewFramer(cc.bw, cc.br)
+	cc.fr.ReadMetaHeaders = hpack.NewDecoder(http2initialHeaderTableSize, nil)
+	cc.fr.MaxHeaderListSize = t.maxHeaderListSize()
 
 	cc.henc = hpack.NewEncoder(&cc.hbuf)
 
@@ -4932,8 +5222,8 @@ func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
 	}
 
 	initialSettings := []http2Setting{
-		http2Setting{ID: http2SettingEnablePush, Val: 0},
-		http2Setting{ID: http2SettingInitialWindowSize, Val: http2transportDefaultStreamFlow},
+		{ID: http2SettingEnablePush, Val: 0},
+		{ID: http2SettingInitialWindowSize, Val: http2transportDefaultStreamFlow},
 	}
 	if max := t.maxHeaderListSize(); max != 0 {
 		initialSettings = append(initialSettings, http2Setting{ID: http2SettingMaxHeaderListSize, Val: max})
@@ -4979,7 +5269,16 @@ func (t *http2Transport) NewClientConn(c net.Conn) (*http2ClientConn, error) {
 func (cc *http2ClientConn) setGoAway(f *http2GoAwayFrame) {
 	cc.mu.Lock()
 	defer cc.mu.Unlock()
+
+	old := cc.goAway
 	cc.goAway = f
+
+	if cc.goAwayDebug == "" {
+		cc.goAwayDebug = string(f.DebugData())
+	}
+	if old != nil && old.ErrCode != http2ErrCodeNo {
+		cc.goAway.ErrCode = old.ErrCode
+	}
 }
 
 func (cc *http2ClientConn) CanTakeNewRequest() bool {
@@ -5093,6 +5392,30 @@ func http2checkConnHeaders(req *Request) error {
 	return nil
 }
 
+func http2bodyAndLength(req *Request) (body io.Reader, contentLen int64) {
+	body = req.Body
+	if body == nil {
+		return nil, 0
+	}
+	if req.ContentLength != 0 {
+		return req.Body, req.ContentLength
+	}
+
+	// We have a body but a zero content length. Test to see if
+	// it's actually zero or just unset.
+	var buf [1]byte
+	n, rerr := io.ReadFull(body, buf[:])
+	if rerr != nil && rerr != io.EOF {
+		return http2errorReader{rerr}, -1
+	}
+	if n == 1 {
+
+		return io.MultiReader(bytes.NewReader(buf[:]), body), -1
+	}
+
+	return nil, 0
+}
+
 func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
 	if err := http2checkConnHeaders(req); err != nil {
 		return nil, err
@@ -5104,67 +5427,62 @@ func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
 	}
 	hasTrailers := trailers != ""
 
-	var body io.Reader = req.Body
-	contentLen := req.ContentLength
-	if req.Body != nil && contentLen == 0 {
-		// Test to see if it's actually zero or just unset.
-		var buf [1]byte
-		n, rerr := io.ReadFull(body, buf[:])
-		if rerr != nil && rerr != io.EOF {
-			contentLen = -1
-			body = http2errorReader{rerr}
-		} else if n == 1 {
-
-			contentLen = -1
-			body = io.MultiReader(bytes.NewReader(buf[:]), body)
-		} else {
-
-			body = nil
-		}
-	}
+	body, contentLen := http2bodyAndLength(req)
+	hasBody := body != nil
 
 	cc.mu.Lock()
+	cc.lastActive = time.Now()
 	if cc.closed || !cc.canTakeNewRequestLocked() {
 		cc.mu.Unlock()
 		return nil, http2errClientConnUnusable
 	}
 
-	cs := cc.newStream()
-	cs.req = req
-	hasBody := body != nil
-
+	// TODO(bradfitz): this is a copy of the logic in net/http. Unify somewhere?
+	var requestedGzip bool
 	if !cc.t.disableCompression() &&
 		req.Header.Get("Accept-Encoding") == "" &&
 		req.Header.Get("Range") == "" &&
 		req.Method != "HEAD" {
 
-		cs.requestedGzip = true
+		requestedGzip = true
 	}
 
-	hdrs := cc.encodeHeaders(req, cs.requestedGzip, trailers, contentLen)
+	hdrs, err := cc.encodeHeaders(req, requestedGzip, trailers, contentLen)
+	if err != nil {
+		cc.mu.Unlock()
+		return nil, err
+	}
+
+	cs := cc.newStream()
+	cs.req = req
+	cs.trace = http2requestTrace(req)
+	cs.requestedGzip = requestedGzip
+	bodyWriter := cc.t.getBodyWriterState(cs, body)
+	cs.on100 = bodyWriter.on100
+
 	cc.wmu.Lock()
 	endStream := !hasBody && !hasTrailers
 	werr := cc.writeHeaders(cs.ID, endStream, hdrs)
 	cc.wmu.Unlock()
+	http2traceWroteHeaders(cs.trace)
 	cc.mu.Unlock()
 
 	if werr != nil {
 		if hasBody {
 			req.Body.Close()
+			bodyWriter.cancel()
 		}
 		cc.forgetStreamID(cs.ID)
 
+		http2traceWroteRequest(cs.trace, werr)
 		return nil, werr
 	}
 
 	var respHeaderTimer <-chan time.Time
-	var bodyCopyErrc chan error // result of body copy
 	if hasBody {
-		bodyCopyErrc = make(chan error, 1)
-		go func() {
-			bodyCopyErrc <- cs.writeRequestBody(body, req.Body)
-		}()
+		bodyWriter.scheduleBodyWrite()
 	} else {
+		http2traceWroteRequest(cs.trace, nil)
 		if d := cc.responseHeaderTimeout(); d != 0 {
 			timer := time.NewTimer(d)
 			defer timer.Stop()
@@ -5173,44 +5491,78 @@ func (cc *http2ClientConn) RoundTrip(req *Request) (*Response, error) {
 	}
 
 	readLoopResCh := cs.resc
-	requestCanceledCh := http2requestCancel(req)
 	bodyWritten := false
+	ctx := http2reqContext(req)
+
+	reFunc := func(re http2resAndError) (*Response, error) {
+		res := re.res
+		if re.err != nil || res.StatusCode > 299 {
+			bodyWriter.cancel()
+			cs.abortRequestBodyWrite(http2errStopReqBodyWrite)
+		}
+		if re.err != nil {
+			cc.forgetStreamID(cs.ID)
+			return nil, re.err
+		}
+		res.Request = req
+		res.TLS = cc.tlsState
+		return res, nil
+	}
 
 	for {
 		select {
 		case re := <-readLoopResCh:
-			res := re.res
-			if re.err != nil || res.StatusCode > 299 {
-
-				cs.abortRequestBodyWrite(http2errStopReqBodyWrite)
-			}
-			if re.err != nil {
-				cc.forgetStreamID(cs.ID)
-				return nil, re.err
-			}
-			res.Request = req
-			res.TLS = cc.tlsState
-			return res, nil
+			return reFunc(re)
 		case <-respHeaderTimer:
 			cc.forgetStreamID(cs.ID)
 			if !hasBody || bodyWritten {
 				cc.writeStreamReset(cs.ID, http2ErrCodeCancel, nil)
 			} else {
+				bodyWriter.cancel()
 				cs.abortRequestBodyWrite(http2errStopReqBodyWriteAndCancel)
 			}
 			return nil, http2errTimeout
-		case <-requestCanceledCh:
+		case <-ctx.Done():
+			select {
+			case re := <-readLoopResCh:
+				return reFunc(re)
+			default:
+			}
+			cc.forgetStreamID(cs.ID)
+			if !hasBody || bodyWritten {
+				cc.writeStreamReset(cs.ID, http2ErrCodeCancel, nil)
+			} else {
+				bodyWriter.cancel()
+				cs.abortRequestBodyWrite(http2errStopReqBodyWriteAndCancel)
+			}
+			return nil, ctx.Err()
+		case <-req.Cancel:
+			select {
+			case re := <-readLoopResCh:
+				return reFunc(re)
+			default:
+			}
 			cc.forgetStreamID(cs.ID)
 			if !hasBody || bodyWritten {
 				cc.writeStreamReset(cs.ID, http2ErrCodeCancel, nil)
 			} else {
+				bodyWriter.cancel()
 				cs.abortRequestBodyWrite(http2errStopReqBodyWriteAndCancel)
 			}
 			return nil, http2errRequestCanceled
 		case <-cs.peerReset:
-
+			select {
+			case re := <-readLoopResCh:
+				return reFunc(re)
+			default:
+			}
 			return nil, cs.resetErr
-		case err := <-bodyCopyErrc:
+		case err := <-bodyWriter.resc:
+			select {
+			case re := <-readLoopResCh:
+				return reFunc(re)
+			default:
+			}
 			if err != nil {
 				return nil, err
 			}
@@ -5268,6 +5620,7 @@ func (cs *http2clientStream) writeRequestBody(body io.Reader, bodyCloser io.Clos
 	defer cc.putFrameScratchBuffer(buf)
 
 	defer func() {
+		http2traceWroteRequest(cs.trace, err)
 
 		cerr := bodyCloser.Close()
 		if err == nil {
@@ -5355,7 +5708,7 @@ func (cs *http2clientStream) awaitFlowControl(maxBytes int) (taken int32, err er
 		if cs.stopReqBody != nil {
 			return 0, cs.stopReqBody
 		}
-		if err := cs.checkReset(); err != nil {
+		if err := cs.checkResetOrDone(); err != nil {
 			return 0, err
 		}
 		if a := cs.flow.available(); a > 0 {
@@ -5382,7 +5735,7 @@ type http2badStringError struct {
 func (e *http2badStringError) Error() string { return fmt.Sprintf("%s %q", e.what, e.str) }
 
 // requires cc.mu be held.
-func (cc *http2ClientConn) encodeHeaders(req *Request, addGzipHeader bool, trailers string, contentLength int64) []byte {
+func (cc *http2ClientConn) encodeHeaders(req *Request, addGzipHeader bool, trailers string, contentLength int64) ([]byte, error) {
 	cc.hbuf.Reset()
 
 	host := req.Host
@@ -5390,6 +5743,17 @@ func (cc *http2ClientConn) encodeHeaders(req *Request, addGzipHeader bool, trail
 		host = req.URL.Host
 	}
 
+	for k, vv := range req.Header {
+		if !httplex.ValidHeaderFieldName(k) {
+			return nil, fmt.Errorf("invalid HTTP header name %q", k)
+		}
+		for _, v := range vv {
+			if !httplex.ValidHeaderFieldValue(v) {
+				return nil, fmt.Errorf("invalid HTTP header value %q for header %q", v, k)
+			}
+		}
+	}
+
 	cc.writeHeader(":authority", host)
 	cc.writeHeader(":method", req.Method)
 	if req.Method != "CONNECT" {
@@ -5407,7 +5771,7 @@ func (cc *http2ClientConn) encodeHeaders(req *Request, addGzipHeader bool, trail
 		case "host", "content-length":
 
 			continue
-		case "connection", "proxy-connection", "transfer-encoding", "upgrade":
+		case "connection", "proxy-connection", "transfer-encoding", "upgrade", "keep-alive":
 
 			continue
 		case "user-agent":
@@ -5434,7 +5798,7 @@ func (cc *http2ClientConn) encodeHeaders(req *Request, addGzipHeader bool, trail
 	if !didUA {
 		cc.writeHeader("user-agent", http2defaultUserAgent)
 	}
-	return cc.hbuf.Bytes()
+	return cc.hbuf.Bytes(), nil
 }
 
 // shouldSendReqContentLength reports whether the http2.Transport should send
@@ -5510,8 +5874,10 @@ func (cc *http2ClientConn) streamByID(id uint32, andRemove bool) *http2clientStr
 	defer cc.mu.Unlock()
 	cs := cc.streams[id]
 	if andRemove && cs != nil && !cc.closed {
+		cc.lastActive = time.Now()
 		delete(cc.streams, id)
 		close(cs.done)
+		cc.cond.Broadcast()
 	}
 	return cs
 }
@@ -5521,15 +5887,6 @@ type http2clientConnReadLoop struct {
 	cc            *http2ClientConn
 	activeRes     map[uint32]*http2clientStream // keyed by streamID
 	closeWhenIdle bool
-
-	hdec *hpack.Decoder
-
-	// Fields reset on each HEADERS:
-	nextRes              *Response
-	sawRegHeader         bool  // saw non-pseudo header
-	reqMalformed         error // non-nil once known to be malformed
-	lastHeaderEndsStream bool
-	headerListSize       int64 // actually uint32, but easier math this way
 }
 
 // readLoop runs in its own goroutine and reads and dispatches frames.
@@ -5538,7 +5895,6 @@ func (cc *http2ClientConn) readLoop() {
 		cc:        cc,
 		activeRes: make(map[uint32]*http2clientStream),
 	}
-	rl.hdec = hpack.NewDecoder(http2initialHeaderTableSize, rl.onNewHeaderField)
 
 	defer rl.cleanup()
 	cc.readerErr = rl.run()
@@ -5549,6 +5905,19 @@ func (cc *http2ClientConn) readLoop() {
 	}
 }
 
+// GoAwayError is returned by the Transport when the server closes the
+// TCP connection after sending a GOAWAY frame.
+type http2GoAwayError struct {
+	LastStreamID uint32
+	ErrCode      http2ErrCode
+	DebugData    string
+}
+
+func (e http2GoAwayError) Error() string {
+	return fmt.Sprintf("http2: server sent GOAWAY and closed the connection; LastStreamID=%v, ErrCode=%v, debug=%q",
+		e.LastStreamID, e.ErrCode, e.DebugData)
+}
+
 func (rl *http2clientConnReadLoop) cleanup() {
 	cc := rl.cc
 	defer cc.tconn.Close()
@@ -5556,10 +5925,18 @@ func (rl *http2clientConnReadLoop) cleanup() {
 	defer close(cc.readerDone)
 
 	err := cc.readerErr
+	cc.mu.Lock()
 	if err == io.EOF {
-		err = io.ErrUnexpectedEOF
+		if cc.goAway != nil {
+			err = http2GoAwayError{
+				LastStreamID: cc.goAway.LastStreamID,
+				ErrCode:      cc.goAway.ErrCode,
+				DebugData:    cc.goAwayDebug,
+			}
+		} else {
+			err = io.ErrUnexpectedEOF
+		}
 	}
-	cc.mu.Lock()
 	for _, cs := range rl.activeRes {
 		cs.bufPipe.CloseWithError(err)
 	}
@@ -5585,8 +5962,10 @@ func (rl *http2clientConnReadLoop) run() error {
 			cc.vlogf("Transport readFrame error: (%T) %v", err, err)
 		}
 		if se, ok := err.(http2StreamError); ok {
-
-			return se
+			if cs := cc.streamByID(se.StreamID, true); cs != nil {
+				rl.endStreamError(cs, cc.fr.errDetail)
+			}
+			continue
 		} else if err != nil {
 			return err
 		}
@@ -5596,13 +5975,10 @@ func (rl *http2clientConnReadLoop) run() error {
 		maybeIdle := false
 
 		switch f := f.(type) {
-		case *http2HeadersFrame:
+		case *http2MetaHeadersFrame:
 			err = rl.processHeaders(f)
 			maybeIdle = true
 			gotReply = true
-		case *http2ContinuationFrame:
-			err = rl.processContinuation(f)
-			maybeIdle = true
 		case *http2DataFrame:
 			err = rl.processData(f)
 			maybeIdle = true
@@ -5632,83 +6008,105 @@ func (rl *http2clientConnReadLoop) run() error {
 	}
 }
 
-func (rl *http2clientConnReadLoop) processHeaders(f *http2HeadersFrame) error {
-	rl.sawRegHeader = false
-	rl.reqMalformed = nil
-	rl.lastHeaderEndsStream = f.StreamEnded()
-	rl.headerListSize = 0
-	rl.nextRes = &Response{
-		Proto:      "HTTP/2.0",
-		ProtoMajor: 2,
-		Header:     make(Header),
-	}
-	rl.hdec.SetEmitEnabled(true)
-	return rl.processHeaderBlockFragment(f.HeaderBlockFragment(), f.StreamID, f.HeadersEnded())
-}
-
-func (rl *http2clientConnReadLoop) processContinuation(f *http2ContinuationFrame) error {
-	return rl.processHeaderBlockFragment(f.HeaderBlockFragment(), f.StreamID, f.HeadersEnded())
-}
-
-func (rl *http2clientConnReadLoop) processHeaderBlockFragment(frag []byte, streamID uint32, finalFrag bool) error {
+func (rl *http2clientConnReadLoop) processHeaders(f *http2MetaHeadersFrame) error {
 	cc := rl.cc
-	streamEnded := rl.lastHeaderEndsStream
-	cs := cc.streamByID(streamID, streamEnded && finalFrag)
+	cs := cc.streamByID(f.StreamID, f.StreamEnded())
 	if cs == nil {
 
 		return nil
 	}
-	if cs.pastHeaders {
-		rl.hdec.SetEmitFunc(func(f hpack.HeaderField) { rl.onNewTrailerField(cs, f) })
-	} else {
-		rl.hdec.SetEmitFunc(rl.onNewHeaderField)
-	}
-	_, err := rl.hdec.Write(frag)
-	if err != nil {
-		return http2ConnectionError(http2ErrCodeCompression)
-	}
-	if finalFrag {
-		if err := rl.hdec.Close(); err != nil {
-			return http2ConnectionError(http2ErrCodeCompression)
-		}
-	}
+	if !cs.firstByte {
+		if cs.trace != nil {
 
-	if !finalFrag {
-		return nil
+			http2traceFirstResponseByte(cs.trace)
+		}
+		cs.firstByte = true
 	}
-
 	if !cs.pastHeaders {
 		cs.pastHeaders = true
 	} else {
+		return rl.processTrailers(cs, f)
+	}
 
-		if cs.pastTrailers {
-
-			return http2ConnectionError(http2ErrCodeProtocol)
+	res, err := rl.handleResponse(cs, f)
+	if err != nil {
+		if _, ok := err.(http2ConnectionError); ok {
+			return err
 		}
-		cs.pastTrailers = true
-		if !streamEnded {
 
-			return http2ConnectionError(http2ErrCodeProtocol)
-		}
-		rl.endStream(cs)
+		cs.cc.writeStreamReset(f.StreamID, http2ErrCodeProtocol, err)
+		cs.resc <- http2resAndError{err: err}
 		return nil
 	}
+	if res == nil {
 
-	if rl.reqMalformed != nil {
-		cs.resc <- http2resAndError{err: rl.reqMalformed}
-		rl.cc.writeStreamReset(cs.ID, http2ErrCodeProtocol, rl.reqMalformed)
 		return nil
 	}
+	if res.Body != http2noBody {
+		rl.activeRes[cs.ID] = cs
+	}
+	cs.resTrailer = &res.Trailer
+	cs.resc <- http2resAndError{res: res}
+	return nil
+}
 
-	res := rl.nextRes
+// may return error types nil, or ConnectionError. Any other error value
+// is a StreamError of type ErrCodeProtocol. The returned error in that case
+// is the detail.
+//
+// As a special case, handleResponse may return (nil, nil) to skip the
+// frame (currently only used for 100 expect continue). This special
+// case is going away after Issue 13851 is fixed.
+func (rl *http2clientConnReadLoop) handleResponse(cs *http2clientStream, f *http2MetaHeadersFrame) (*Response, error) {
+	if f.Truncated {
+		return nil, http2errResponseHeaderListSize
+	}
 
-	if res.StatusCode == 100 {
+	status := f.PseudoValue("status")
+	if status == "" {
+		return nil, errors.New("missing status pseudo header")
+	}
+	statusCode, err := strconv.Atoi(status)
+	if err != nil {
+		return nil, errors.New("malformed non-numeric status pseudo header")
+	}
 
+	if statusCode == 100 {
+		http2traceGot100Continue(cs.trace)
+		if cs.on100 != nil {
+			cs.on100()
+		}
 		cs.pastHeaders = false
-		return nil
+		return nil, nil
+	}
+
+	header := make(Header)
+	res := &Response{
+		Proto:      "HTTP/2.0",
+		ProtoMajor: 2,
+		Header:     header,
+		StatusCode: statusCode,
+		Status:     status + " " + StatusText(statusCode),
+	}
+	for _, hf := range f.RegularFields() {
+		key := CanonicalHeaderKey(hf.Name)
+		if key == "Trailer" {
+			t := res.Trailer
+			if t == nil {
+				t = make(Header)
+				res.Trailer = t
+			}
+			http2foreachHeaderElement(hf.Value, func(v string) {
+				t[CanonicalHeaderKey(v)] = nil
+			})
+		} else {
+			header[key] = append(header[key], hf.Value)
+		}
 	}
 
-	if !streamEnded || cs.req.Method == "HEAD" {
+	streamEnded := f.StreamEnded()
+	isHead := cs.req.Method == "HEAD"
+	if !streamEnded || isHead {
 		res.ContentLength = -1
 		if clens := res.Header["Content-Length"]; len(clens) == 1 {
 			if clen64, err := strconv.ParseInt(clens[0], 10, 64); err == nil {
@@ -5721,27 +6119,50 @@ func (rl *http2clientConnReadLoop) processHeaderBlockFragment(frag []byte, strea
 		}
 	}
 
-	if streamEnded {
+	if streamEnded || isHead {
 		res.Body = http2noBody
-	} else {
-		buf := new(bytes.Buffer)
-		cs.bufPipe = http2pipe{b: buf}
-		cs.bytesRemain = res.ContentLength
-		res.Body = http2transportResponseBody{cs}
-		go cs.awaitRequestCancel(http2requestCancel(cs.req))
-
-		if cs.requestedGzip && res.Header.Get("Content-Encoding") == "gzip" {
-			res.Header.Del("Content-Encoding")
-			res.Header.Del("Content-Length")
-			res.ContentLength = -1
-			res.Body = &http2gzipReader{body: res.Body}
-		}
-		rl.activeRes[cs.ID] = cs
+		return res, nil
 	}
 
-	cs.resTrailer = &res.Trailer
-	cs.resc <- http2resAndError{res: res}
-	rl.nextRes = nil
+	buf := new(bytes.Buffer)
+	cs.bufPipe = http2pipe{b: buf}
+	cs.bytesRemain = res.ContentLength
+	res.Body = http2transportResponseBody{cs}
+	go cs.awaitRequestCancel(cs.req)
+
+	if cs.requestedGzip && res.Header.Get("Content-Encoding") == "gzip" {
+		res.Header.Del("Content-Encoding")
+		res.Header.Del("Content-Length")
+		res.ContentLength = -1
+		res.Body = &http2gzipReader{body: res.Body}
+		http2setResponseUncompressed(res)
+	}
+	return res, nil
+}
+
+func (rl *http2clientConnReadLoop) processTrailers(cs *http2clientStream, f *http2MetaHeadersFrame) error {
+	if cs.pastTrailers {
+
+		return http2ConnectionError(http2ErrCodeProtocol)
+	}
+	cs.pastTrailers = true
+	if !f.StreamEnded() {
+
+		return http2ConnectionError(http2ErrCodeProtocol)
+	}
+	if len(f.PseudoFields()) > 0 {
+
+		return http2ConnectionError(http2ErrCodeProtocol)
+	}
+
+	trailer := make(Header)
+	for _, hf := range f.RegularFields() {
+		key := CanonicalHeaderKey(hf.Name)
+		trailer[key] = append(trailer[key], hf.Value)
+	}
+	cs.trailer = trailer
+
+	rl.endStream(cs)
 	return nil
 }
 
@@ -5792,8 +6213,10 @@ func (b http2transportResponseBody) Read(p []byte) (n int, err error) {
 		cc.inflow.add(connAdd)
 	}
 	if err == nil {
-		if v := cs.inflow.available(); v < http2transportDefaultStreamFlow-http2transportDefaultStreamMinRefresh {
-			streamAdd = http2transportDefaultStreamFlow - v
+
+		v := int(cs.inflow.available()) + cs.bufPipe.Len()
+		if v < http2transportDefaultStreamFlow-http2transportDefaultStreamMinRefresh {
+			streamAdd = int32(http2transportDefaultStreamFlow - v)
 			cs.inflow.add(streamAdd)
 		}
 	}
@@ -5855,6 +6278,7 @@ func (rl *http2clientConnReadLoop) processData(f *http2DataFrame) error {
 		cc.mu.Unlock()
 
 		if _, err := cs.bufPipe.Write(data); err != nil {
+			rl.endStreamError(cs, err)
 			return err
 		}
 	}
@@ -5869,11 +6293,14 @@ var http2errInvalidTrailers = errors.New("http2: invalid trailers")
 
 func (rl *http2clientConnReadLoop) endStream(cs *http2clientStream) {
 
-	err := io.EOF
-	code := cs.copyTrailers
-	if rl.reqMalformed != nil {
-		err = rl.reqMalformed
-		code = nil
+	rl.endStreamError(cs, nil)
+}
+
+func (rl *http2clientConnReadLoop) endStreamError(cs *http2clientStream, err error) {
+	var code func()
+	if err == nil {
+		err = io.EOF
+		code = cs.copyTrailers
 	}
 	cs.bufPipe.closeWithErrorAndCode(err, code)
 	delete(rl.activeRes, cs.ID)
@@ -5997,113 +6424,6 @@ var (
 	http2errPseudoTrailers         = errors.New("http2: invalid pseudo header in trailers")
 )
 
-func (rl *http2clientConnReadLoop) checkHeaderField(f hpack.HeaderField) bool {
-	if rl.reqMalformed != nil {
-		return false
-	}
-
-	const headerFieldOverhead = 32 // per spec
-	rl.headerListSize += int64(len(f.Name)) + int64(len(f.Value)) + headerFieldOverhead
-	if max := rl.cc.t.maxHeaderListSize(); max != 0 && rl.headerListSize > int64(max) {
-		rl.hdec.SetEmitEnabled(false)
-		rl.reqMalformed = http2errResponseHeaderListSize
-		return false
-	}
-
-	if !http2validHeaderFieldValue(f.Value) {
-		rl.reqMalformed = http2errInvalidHeaderFieldValue
-		return false
-	}
-
-	isPseudo := strings.HasPrefix(f.Name, ":")
-	if isPseudo {
-		if rl.sawRegHeader {
-			rl.reqMalformed = errors.New("http2: invalid pseudo header after regular header")
-			return false
-		}
-	} else {
-		if !http2validHeaderFieldName(f.Name) {
-			rl.reqMalformed = http2errInvalidHeaderFieldName
-			return false
-		}
-		rl.sawRegHeader = true
-	}
-
-	return true
-}
-
-// onNewHeaderField runs on the readLoop goroutine whenever a new
-// hpack header field is decoded.
-func (rl *http2clientConnReadLoop) onNewHeaderField(f hpack.HeaderField) {
-	cc := rl.cc
-	if http2VerboseLogs {
-		cc.logf("http2: Transport decoded %v", f)
-	}
-
-	if !rl.checkHeaderField(f) {
-		return
-	}
-
-	isPseudo := strings.HasPrefix(f.Name, ":")
-	if isPseudo {
-		switch f.Name {
-		case ":status":
-			code, err := strconv.Atoi(f.Value)
-			if err != nil {
-				rl.reqMalformed = errors.New("http2: invalid :status")
-				return
-			}
-			rl.nextRes.Status = f.Value + " " + StatusText(code)
-			rl.nextRes.StatusCode = code
-		default:
-
-			rl.reqMalformed = fmt.Errorf("http2: unknown response pseudo header %q", f.Name)
-		}
-		return
-	}
-
-	key := CanonicalHeaderKey(f.Name)
-	if key == "Trailer" {
-		t := rl.nextRes.Trailer
-		if t == nil {
-			t = make(Header)
-			rl.nextRes.Trailer = t
-		}
-		http2foreachHeaderElement(f.Value, func(v string) {
-			t[CanonicalHeaderKey(v)] = nil
-		})
-	} else {
-		rl.nextRes.Header.Add(key, f.Value)
-	}
-}
-
-func (rl *http2clientConnReadLoop) onNewTrailerField(cs *http2clientStream, f hpack.HeaderField) {
-	if http2VerboseLogs {
-		rl.cc.logf("http2: Transport decoded trailer %v", f)
-	}
-	if !rl.checkHeaderField(f) {
-		return
-	}
-	if strings.HasPrefix(f.Name, ":") {
-
-		rl.reqMalformed = http2errPseudoTrailers
-		return
-	}
-
-	key := CanonicalHeaderKey(f.Name)
-
-	// The spec says one must predeclare their trailers but in practice
-	// popular users (which is to say the only user we found) do not so we
-	// violate the spec and accept all of them.
-	const acceptAllTrailers = true
-	if _, ok := (*cs.resTrailer)[key]; ok || acceptAllTrailers {
-		if cs.trailer == nil {
-			cs.trailer = make(Header)
-		}
-		cs.trailer[key] = append(cs.trailer[key], f.Value)
-	}
-}
-
 func (cc *http2ClientConn) logf(format string, args ...interface{}) {
 	cc.t.logf(format, args...)
 }
@@ -6167,6 +6487,79 @@ type http2errorReader struct{ err error }
 
 func (r http2errorReader) Read(p []byte) (int, error) { return 0, r.err }
 
+// bodyWriterState encapsulates various state around the Transport's writing
+// of the request body, particularly regarding doing delayed writes of the body
+// when the request contains "Expect: 100-continue".
+type http2bodyWriterState struct {
+	cs     *http2clientStream
+	timer  *time.Timer   // if non-nil, we're doing a delayed write
+	fnonce *sync.Once    // to call fn with
+	fn     func()        // the code to run in the goroutine, writing the body
+	resc   chan error    // result of fn's execution
+	delay  time.Duration // how long we should delay a delayed write for
+}
+
+func (t *http2Transport) getBodyWriterState(cs *http2clientStream, body io.Reader) (s http2bodyWriterState) {
+	s.cs = cs
+	if body == nil {
+		return
+	}
+	resc := make(chan error, 1)
+	s.resc = resc
+	s.fn = func() {
+		resc <- cs.writeRequestBody(body, cs.req.Body)
+	}
+	s.delay = t.expectContinueTimeout()
+	if s.delay == 0 ||
+		!httplex.HeaderValuesContainsToken(
+			cs.req.Header["Expect"],
+			"100-continue") {
+		return
+	}
+	s.fnonce = new(sync.Once)
+
+	// Arm the timer with a very large duration, which we'll
+	// intentionally lower later. It has to be large now because
+	// we need a handle to it before writing the headers, but the
+	// s.delay value is defined to not start until after the
+	// request headers were written.
+	const hugeDuration = 365 * 24 * time.Hour
+	s.timer = time.AfterFunc(hugeDuration, func() {
+		s.fnonce.Do(s.fn)
+	})
+	return
+}
+
+func (s http2bodyWriterState) cancel() {
+	if s.timer != nil {
+		s.timer.Stop()
+	}
+}
+
+func (s http2bodyWriterState) on100() {
+	if s.timer == nil {
+
+		return
+	}
+	s.timer.Stop()
+	go func() { s.fnonce.Do(s.fn) }()
+}
+
+// scheduleBodyWrite starts writing the body, either immediately (in
+// the common case) or after the delay timeout. It should not be
+// called until after the headers have been written.
+func (s http2bodyWriterState) scheduleBodyWrite() {
+	if s.timer == nil {
+
+		go s.fn()
+		return
+	}
+	http2traceWait100Continue(s.cs.trace)
+	if s.timer.Stop() {
+		s.timer.Reset(s.delay)
+	}
+}
+
 // writeFramer is implemented by any type that is used to write frames.
 type http2writeFramer interface {
 	writeFrame(http2writeContext) error
@@ -6380,24 +6773,22 @@ func (wu http2writeWindowUpdate) writeFrame(ctx http2writeContext) error {
 }
 
 func http2encodeHeaders(enc *hpack.Encoder, h Header, keys []string) {
-
 	if keys == nil {
-		keys = make([]string, 0, len(h))
-		for k := range h {
-			keys = append(keys, k)
-		}
-		sort.Strings(keys)
+		sorter := http2sorterPool.Get().(*http2sorter)
+
+		defer http2sorterPool.Put(sorter)
+		keys = sorter.Keys(h)
 	}
 	for _, k := range keys {
 		vv := h[k]
 		k = http2lowerHeader(k)
-		if !http2validHeaderFieldName(k) {
+		if !http2validWireHeaderFieldName(k) {
 
 			continue
 		}
 		isTE := k == "transfer-encoding"
 		for _, v := range vv {
-			if !http2validHeaderFieldValue(v) {
+			if !httplex.ValidHeaderFieldValue(v) {
 
 				continue
 			}
diff --git a/libgo/go/net/http/header.go b/libgo/go/net/http/header.go
index 049f32f27dc..6343165a840 100644
--- a/libgo/go/net/http/header.go
+++ b/libgo/go/net/http/header.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -25,7 +25,7 @@ func (h Header) Add(key, value string) {
 }
 
 // Set sets the header entries associated with key to
-// the single element value.  It replaces any existing
+// the single element value. It replaces any existing
 // values associated with key.
 func (h Header) Set(key, value string) {
 	textproto.MIMEHeader(h).Set(key, value)
@@ -164,9 +164,9 @@ func (h Header) WriteSubset(w io.Writer, exclude map[string]bool) error {
 }
 
 // CanonicalHeaderKey returns the canonical format of the
-// header key s.  The canonicalization converts the first
+// header key s. The canonicalization converts the first
 // letter and any letter following a hyphen to upper case;
-// the rest are converted to lowercase.  For example, the
+// the rest are converted to lowercase. For example, the
 // canonical key for "accept-encoding" is "Accept-Encoding".
 // If s contains a space or invalid header field bytes, it is
 // returned without modifications.
@@ -186,7 +186,7 @@ func hasToken(v, token string) bool {
 	for sp := 0; sp <= len(v)-len(token); sp++ {
 		// Check that first character is good.
 		// The token is ASCII, so checking only a single byte
-		// is sufficient.  We skip this potential starting
+		// is sufficient. We skip this potential starting
 		// position if both the first byte and its potential
 		// ASCII uppercase equivalent (b|0x20) don't match.
 		// False positives ('^' => '~') are caught by EqualFold.
diff --git a/libgo/go/net/http/header_test.go b/libgo/go/net/http/header_test.go
index 299576ba8cf..5c0de15b731 100644
--- a/libgo/go/net/http/header_test.go
+++ b/libgo/go/net/http/header_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/http/http.go b/libgo/go/net/http/http.go
new file mode 100644
index 00000000000..b34ae41ec51
--- /dev/null
+++ b/libgo/go/net/http/http.go
@@ -0,0 +1,43 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package http
+
+import (
+	"strings"
+
+	"golang_org/x/net/lex/httplex"
+)
+
+// maxInt64 is the effective "infinite" value for the Server and
+// Transport's byte-limiting readers.
+const maxInt64 = 1<<63 - 1
+
+// TODO(bradfitz): move common stuff here. The other files have accumulated
+// generic http stuff in random places.
+
+// contextKey is a value for use with context.WithValue. It's used as
+// a pointer so it fits in an interface{} without allocation.
+type contextKey struct {
+	name string
+}
+
+func (k *contextKey) String() string { return "net/http context value " + k.name }
+
+// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
+// return true if the string includes a port.
+func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
+
+// removeEmptyPort strips the empty port in ":port" to ""
+// as mandated by RFC 3986 Section 6.2.3.
+func removeEmptyPort(host string) string {
+	if hasPort(host) {
+		return strings.TrimSuffix(host, ":")
+	}
+	return host
+}
+
+func isNotToken(r rune) bool {
+	return !httplex.IsTokenRune(r)
+}
diff --git a/libgo/go/net/http/http_test.go b/libgo/go/net/http/http_test.go
index dead3b04542..34da4bbb59e 100644
--- a/libgo/go/net/http/http_test.go
+++ b/libgo/go/net/http/http_test.go
@@ -2,11 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Tests of internal functions with no better homes.
+// Tests of internal functions and things with no better homes.
 
 package http
 
 import (
+	"bytes"
+	"internal/testenv"
+	"os/exec"
 	"reflect"
 	"testing"
 )
@@ -56,3 +59,35 @@ func TestCleanHost(t *testing.T) {
 		}
 	}
 }
+
+// Test that cmd/go doesn't link in the HTTP server.
+//
+// This catches accidental dependencies between the HTTP transport and
+// server code.
+func TestCmdGoNoHTTPServer(t *testing.T) {
+	goBin := testenv.GoToolPath(t)
+	out, err := exec.Command("go", "tool", "nm", goBin).CombinedOutput()
+	if err != nil {
+		t.Fatalf("go tool nm: %v: %s", err, out)
+	}
+	wantSym := map[string]bool{
+		// Verify these exist: (sanity checking this test)
+		"net/http.(*Client).Get":          true,
+		"net/http.(*Transport).RoundTrip": true,
+
+		// Verify these don't exist:
+		"net/http.http2Server":           false,
+		"net/http.(*Server).Serve":       false,
+		"net/http.(*ServeMux).ServeHTTP": false,
+		"net/http.DefaultServeMux":       false,
+	}
+	for sym, want := range wantSym {
+		got := bytes.Contains(out, []byte(sym))
+		if !want && got {
+			t.Errorf("cmd/go unexpectedly links in HTTP server code; found symbol %q in cmd/go", sym)
+		}
+		if want && !got {
+			t.Errorf("expected to find symbol %q in cmd/go; not found", sym)
+		}
+	}
+}
diff --git a/libgo/go/net/http/httptest/httptest.go b/libgo/go/net/http/httptest/httptest.go
new file mode 100644
index 00000000000..e2148a659c1
--- /dev/null
+++ b/libgo/go/net/http/httptest/httptest.go
@@ -0,0 +1,88 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package httptest provides utilities for HTTP testing.
+package httptest
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/tls"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+// NewRequest returns a new incoming server Request, suitable
+// for passing to an http.Handler for testing.
+//
+// The target is the RFC 7230 "request-target": it may be either a
+// path or an absolute URL. If target is an absolute URL, the host name
+// from the URL is used. Otherwise, "example.com" is used.
+//
+// The TLS field is set to a non-nil dummy value if target has scheme
+// "https".
+//
+// The Request.Proto is always HTTP/1.1.
+//
+// An empty method means "GET".
+//
+// The provided body may be nil. If the body is of type *bytes.Reader,
+// *strings.Reader, or *bytes.Buffer, the Request.ContentLength is
+// set.
+//
+// NewRequest panics on error for ease of use in testing, where a
+// panic is acceptable.
+func NewRequest(method, target string, body io.Reader) *http.Request {
+	if method == "" {
+		method = "GET"
+	}
+	req, err := http.ReadRequest(bufio.NewReader(strings.NewReader(method + " " + target + " HTTP/1.0\r\n\r\n")))
+	if err != nil {
+		panic("invalid NewRequest arguments; " + err.Error())
+	}
+
+	// HTTP/1.0 was used above to avoid needing a Host field. Change it to 1.1 here.
+	req.Proto = "HTTP/1.1"
+	req.ProtoMinor = 1
+	req.Close = false
+
+	if body != nil {
+		switch v := body.(type) {
+		case *bytes.Buffer:
+			req.ContentLength = int64(v.Len())
+		case *bytes.Reader:
+			req.ContentLength = int64(v.Len())
+		case *strings.Reader:
+			req.ContentLength = int64(v.Len())
+		default:
+			req.ContentLength = -1
+		}
+		if rc, ok := body.(io.ReadCloser); ok {
+			req.Body = rc
+		} else {
+			req.Body = ioutil.NopCloser(body)
+		}
+	}
+
+	// 192.0.2.0/24 is "TEST-NET" in RFC 5737 for use solely in
+	// documentation and example source code and should not be
+	// used publicly.
+	req.RemoteAddr = "192.0.2.1:1234"
+
+	if req.Host == "" {
+		req.Host = "example.com"
+	}
+
+	if strings.HasPrefix(target, "https://") {
+		req.TLS = &tls.ConnectionState{
+			Version:           tls.VersionTLS12,
+			HandshakeComplete: true,
+			ServerName:        req.Host,
+		}
+	}
+
+	return req
+}
diff --git a/libgo/go/net/http/httptest/httptest_test.go b/libgo/go/net/http/httptest/httptest_test.go
new file mode 100644
index 00000000000..4f9ecbd8bbc
--- /dev/null
+++ b/libgo/go/net/http/httptest/httptest_test.go
@@ -0,0 +1,177 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package httptest
+
+import (
+	"crypto/tls"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestNewRequest(t *testing.T) {
+	tests := [...]struct {
+		method, uri string
+		body        io.Reader
+
+		want     *http.Request
+		wantBody string
+	}{
+		// Empty method means GET:
+		0: {
+			method: "",
+			uri:    "/",
+			body:   nil,
+			want: &http.Request{
+				Method:     "GET",
+				Host:       "example.com",
+				URL:        &url.URL{Path: "/"},
+				Header:     http.Header{},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				RemoteAddr: "192.0.2.1:1234",
+				RequestURI: "/",
+			},
+			wantBody: "",
+		},
+
+		// GET with full URL:
+		1: {
+			method: "GET",
+			uri:    "http://foo.com/path/%2f/bar/",
+			body:   nil,
+			want: &http.Request{
+				Method: "GET",
+				Host:   "foo.com",
+				URL: &url.URL{
+					Scheme:  "http",
+					Path:    "/path///bar/",
+					RawPath: "/path/%2f/bar/",
+					Host:    "foo.com",
+				},
+				Header:     http.Header{},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				RemoteAddr: "192.0.2.1:1234",
+				RequestURI: "http://foo.com/path/%2f/bar/",
+			},
+			wantBody: "",
+		},
+
+		// GET with full https URL:
+		2: {
+			method: "GET",
+			uri:    "https://foo.com/path/",
+			body:   nil,
+			want: &http.Request{
+				Method: "GET",
+				Host:   "foo.com",
+				URL: &url.URL{
+					Scheme: "https",
+					Path:   "/path/",
+					Host:   "foo.com",
+				},
+				Header:     http.Header{},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				RemoteAddr: "192.0.2.1:1234",
+				RequestURI: "https://foo.com/path/",
+				TLS: &tls.ConnectionState{
+					Version:           tls.VersionTLS12,
+					HandshakeComplete: true,
+					ServerName:        "foo.com",
+				},
+			},
+			wantBody: "",
+		},
+
+		// Post with known length
+		3: {
+			method: "POST",
+			uri:    "/",
+			body:   strings.NewReader("foo"),
+			want: &http.Request{
+				Method:        "POST",
+				Host:          "example.com",
+				URL:           &url.URL{Path: "/"},
+				Header:        http.Header{},
+				Proto:         "HTTP/1.1",
+				ContentLength: 3,
+				ProtoMajor:    1,
+				ProtoMinor:    1,
+				RemoteAddr:    "192.0.2.1:1234",
+				RequestURI:    "/",
+			},
+			wantBody: "foo",
+		},
+
+		// Post with unknown length
+		4: {
+			method: "POST",
+			uri:    "/",
+			body:   struct{ io.Reader }{strings.NewReader("foo")},
+			want: &http.Request{
+				Method:        "POST",
+				Host:          "example.com",
+				URL:           &url.URL{Path: "/"},
+				Header:        http.Header{},
+				Proto:         "HTTP/1.1",
+				ContentLength: -1,
+				ProtoMajor:    1,
+				ProtoMinor:    1,
+				RemoteAddr:    "192.0.2.1:1234",
+				RequestURI:    "/",
+			},
+			wantBody: "foo",
+		},
+
+		// OPTIONS *
+		5: {
+			method: "OPTIONS",
+			uri:    "*",
+			want: &http.Request{
+				Method:     "OPTIONS",
+				Host:       "example.com",
+				URL:        &url.URL{Path: "*"},
+				Header:     http.Header{},
+				Proto:      "HTTP/1.1",
+				ProtoMajor: 1,
+				ProtoMinor: 1,
+				RemoteAddr: "192.0.2.1:1234",
+				RequestURI: "*",
+			},
+		},
+	}
+	for i, tt := range tests {
+		got := NewRequest(tt.method, tt.uri, tt.body)
+		slurp, err := ioutil.ReadAll(got.Body)
+		if err != nil {
+			t.Errorf("%d. ReadAll: %v", i, err)
+		}
+		if string(slurp) != tt.wantBody {
+			t.Errorf("%d. Body = %q; want %q", i, slurp, tt.wantBody)
+		}
+		got.Body = nil // before DeepEqual
+		if !reflect.DeepEqual(got.URL, tt.want.URL) {
+			t.Errorf("%d. Request.URL mismatch:\n got: %#v\nwant: %#v", i, got.URL, tt.want.URL)
+		}
+		if !reflect.DeepEqual(got.Header, tt.want.Header) {
+			t.Errorf("%d. Request.Header mismatch:\n got: %#v\nwant: %#v", i, got.Header, tt.want.Header)
+		}
+		if !reflect.DeepEqual(got.TLS, tt.want.TLS) {
+			t.Errorf("%d. Request.TLS mismatch:\n got: %#v\nwant: %#v", i, got.TLS, tt.want.TLS)
+		}
+		if !reflect.DeepEqual(got, tt.want) {
+			t.Errorf("%d. Request mismatch:\n got: %#v\nwant: %#v", i, got, tt.want)
+		}
+	}
+}
diff --git a/libgo/go/net/http/httptest/recorder.go b/libgo/go/net/http/httptest/recorder.go
index 7c51af1867a..0ad26a3d418 100644
--- a/libgo/go/net/http/httptest/recorder.go
+++ b/libgo/go/net/http/httptest/recorder.go
@@ -2,11 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package httptest provides utilities for HTTP testing.
 package httptest
 
 import (
 	"bytes"
+	"io/ioutil"
 	"net/http"
 )
 
@@ -18,6 +18,8 @@ type ResponseRecorder struct {
 	Body      *bytes.Buffer // if non-nil, the bytes.Buffer to append written data to
 	Flushed   bool
 
+	result      *http.Response // cache of Result's return value
+	snapHeader  http.Header    // snapshot of HeaderMap at first Write
 	wroteHeader bool
 }
 
@@ -59,16 +61,15 @@ func (rw *ResponseRecorder) writeHeader(b []byte, str string) {
 		str = str[:512]
 	}
 
-	_, hasType := rw.HeaderMap["Content-Type"]
-	hasTE := rw.HeaderMap.Get("Transfer-Encoding") != ""
+	m := rw.Header()
+
+	_, hasType := m["Content-Type"]
+	hasTE := m.Get("Transfer-Encoding") != ""
 	if !hasType && !hasTE {
 		if b == nil {
 			b = []byte(str)
 		}
-		if rw.HeaderMap == nil {
-			rw.HeaderMap = make(http.Header)
-		}
-		rw.HeaderMap.Set("Content-Type", http.DetectContentType(b))
+		m.Set("Content-Type", http.DetectContentType(b))
 	}
 
 	rw.WriteHeader(200)
@@ -92,12 +93,28 @@ func (rw *ResponseRecorder) WriteString(str string) (int, error) {
 	return len(str), nil
 }
 
-// WriteHeader sets rw.Code.
+// WriteHeader sets rw.Code. After it is called, changing rw.Header
+// will not affect rw.HeaderMap.
 func (rw *ResponseRecorder) WriteHeader(code int) {
-	if !rw.wroteHeader {
-		rw.Code = code
-		rw.wroteHeader = true
+	if rw.wroteHeader {
+		return
+	}
+	rw.Code = code
+	rw.wroteHeader = true
+	if rw.HeaderMap == nil {
+		rw.HeaderMap = make(http.Header)
 	}
+	rw.snapHeader = cloneHeader(rw.HeaderMap)
+}
+
+func cloneHeader(h http.Header) http.Header {
+	h2 := make(http.Header, len(h))
+	for k, vv := range h {
+		vv2 := make([]string, len(vv))
+		copy(vv2, vv)
+		h2[k] = vv2
+	}
+	return h2
 }
 
 // Flush sets rw.Flushed to true.
@@ -107,3 +124,62 @@ func (rw *ResponseRecorder) Flush() {
 	}
 	rw.Flushed = true
 }
+
+// Result returns the response generated by the handler.
+//
+// The returned Response will have at least its StatusCode,
+// Header, Body, and optionally Trailer populated.
+// More fields may be populated in the future, so callers should
+// not DeepEqual the result in tests.
+//
+// The Response.Header is a snapshot of the headers at the time of the
+// first write call, or at the time of this call, if the handler never
+// did a write.
+//
+// Result must only be called after the handler has finished running.
+func (rw *ResponseRecorder) Result() *http.Response {
+	if rw.result != nil {
+		return rw.result
+	}
+	if rw.snapHeader == nil {
+		rw.snapHeader = cloneHeader(rw.HeaderMap)
+	}
+	res := &http.Response{
+		Proto:      "HTTP/1.1",
+		ProtoMajor: 1,
+		ProtoMinor: 1,
+		StatusCode: rw.Code,
+		Header:     rw.snapHeader,
+	}
+	rw.result = res
+	if res.StatusCode == 0 {
+		res.StatusCode = 200
+	}
+	res.Status = http.StatusText(res.StatusCode)
+	if rw.Body != nil {
+		res.Body = ioutil.NopCloser(bytes.NewReader(rw.Body.Bytes()))
+	}
+
+	if trailers, ok := rw.snapHeader["Trailer"]; ok {
+		res.Trailer = make(http.Header, len(trailers))
+		for _, k := range trailers {
+			// TODO: use http2.ValidTrailerHeader, but we can't
+			// get at it easily because it's bundled into net/http
+			// unexported. This is good enough for now:
+			switch k {
+			case "Transfer-Encoding", "Content-Length", "Trailer":
+				// Ignore since forbidden by RFC 2616 14.40.
+				continue
+			}
+			k = http.CanonicalHeaderKey(k)
+			vv, ok := rw.HeaderMap[k]
+			if !ok {
+				continue
+			}
+			vv2 := make([]string, len(vv))
+			copy(vv2, vv)
+			res.Trailer[k] = vv2
+		}
+	}
+	return res
+}
diff --git a/libgo/go/net/http/httptest/recorder_test.go b/libgo/go/net/http/httptest/recorder_test.go
index c29b6d4cf91..d4e7137913e 100644
--- a/libgo/go/net/http/httptest/recorder_test.go
+++ b/libgo/go/net/http/httptest/recorder_test.go
@@ -23,6 +23,14 @@ func TestRecorder(t *testing.T) {
 			return nil
 		}
 	}
+	hasResultStatus := func(wantCode int) checkFunc {
+		return func(rec *ResponseRecorder) error {
+			if rec.Result().StatusCode != wantCode {
+				return fmt.Errorf("Result().StatusCode = %d; want %d", rec.Result().StatusCode, wantCode)
+			}
+			return nil
+		}
+	}
 	hasContents := func(want string) checkFunc {
 		return func(rec *ResponseRecorder) error {
 			if rec.Body.String() != want {
@@ -39,10 +47,49 @@ func TestRecorder(t *testing.T) {
 			return nil
 		}
 	}
-	hasHeader := func(key, want string) checkFunc {
+	hasOldHeader := func(key, want string) checkFunc {
 		return func(rec *ResponseRecorder) error {
 			if got := rec.HeaderMap.Get(key); got != want {
-				return fmt.Errorf("header %s = %q; want %q", key, got, want)
+				return fmt.Errorf("HeaderMap header %s = %q; want %q", key, got, want)
+			}
+			return nil
+		}
+	}
+	hasHeader := func(key, want string) checkFunc {
+		return func(rec *ResponseRecorder) error {
+			if got := rec.Result().Header.Get(key); got != want {
+				return fmt.Errorf("final header %s = %q; want %q", key, got, want)
+			}
+			return nil
+		}
+	}
+	hasNotHeaders := func(keys ...string) checkFunc {
+		return func(rec *ResponseRecorder) error {
+			for _, k := range keys {
+				v, ok := rec.Result().Header[http.CanonicalHeaderKey(k)]
+				if ok {
+					return fmt.Errorf("unexpected header %s with value %q", k, v)
+				}
+			}
+			return nil
+		}
+	}
+	hasTrailer := func(key, want string) checkFunc {
+		return func(rec *ResponseRecorder) error {
+			if got := rec.Result().Trailer.Get(key); got != want {
+				return fmt.Errorf("trailer %s = %q; want %q", key, got, want)
+			}
+			return nil
+		}
+	}
+	hasNotTrailers := func(keys ...string) checkFunc {
+		return func(rec *ResponseRecorder) error {
+			trailers := rec.Result().Trailer
+			for _, k := range keys {
+				_, ok := trailers[http.CanonicalHeaderKey(k)]
+				if ok {
+					return fmt.Errorf("unexpected trailer %s", k)
+				}
 			}
 			return nil
 		}
@@ -130,6 +177,73 @@ func TestRecorder(t *testing.T) {
 			},
 			check(hasHeader("Content-Type", "text/html; charset=utf-8")),
 		},
+		{
+			"Header is not changed after write",
+			func(w http.ResponseWriter, r *http.Request) {
+				hdr := w.Header()
+				hdr.Set("Key", "correct")
+				w.WriteHeader(200)
+				hdr.Set("Key", "incorrect")
+			},
+			check(hasHeader("Key", "correct")),
+		},
+		{
+			"Trailer headers are correctly recorded",
+			func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("Non-Trailer", "correct")
+				w.Header().Set("Trailer", "Trailer-A")
+				w.Header().Add("Trailer", "Trailer-B")
+				w.Header().Add("Trailer", "Trailer-C")
+				io.WriteString(w, "<html>")
+				w.Header().Set("Non-Trailer", "incorrect")
+				w.Header().Set("Trailer-A", "valuea")
+				w.Header().Set("Trailer-C", "valuec")
+				w.Header().Set("Trailer-NotDeclared", "should be omitted")
+			},
+			check(
+				hasStatus(200),
+				hasHeader("Content-Type", "text/html; charset=utf-8"),
+				hasHeader("Non-Trailer", "correct"),
+				hasNotHeaders("Trailer-A", "Trailer-B", "Trailer-C", "Trailer-NotDeclared"),
+				hasTrailer("Trailer-A", "valuea"),
+				hasTrailer("Trailer-C", "valuec"),
+				hasNotTrailers("Non-Trailer", "Trailer-B", "Trailer-NotDeclared"),
+			),
+		},
+		{
+			"Header set without any write", // Issue 15560
+			func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("X-Foo", "1")
+
+				// Simulate somebody using
+				// new(ResponseRecorder) instead of
+				// using the constructor which sets
+				// this to 200
+				w.(*ResponseRecorder).Code = 0
+			},
+			check(
+				hasOldHeader("X-Foo", "1"),
+				hasStatus(0),
+				hasHeader("X-Foo", "1"),
+				hasResultStatus(200),
+			),
+		},
+		{
+			"HeaderMap vs FinalHeaders", // more for Issue 15560
+			func(w http.ResponseWriter, r *http.Request) {
+				h := w.Header()
+				h.Set("X-Foo", "1")
+				w.Write([]byte("hi"))
+				h.Set("X-Foo", "2")
+				h.Set("X-Bar", "2")
+			},
+			check(
+				hasOldHeader("X-Foo", "2"),
+				hasOldHeader("X-Bar", "2"),
+				hasHeader("X-Foo", "1"),
+				hasNotHeaders("X-Bar"),
+			),
+		},
 	}
 	r, _ := http.NewRequest("GET", "http://foo.com/", nil)
 	for _, tt := range tests {
diff --git a/libgo/go/net/http/httptest/server.go b/libgo/go/net/http/httptest/server.go
index bbe323396f5..e27526a937a 100644
--- a/libgo/go/net/http/httptest/server.go
+++ b/libgo/go/net/http/httptest/server.go
@@ -158,7 +158,7 @@ func (s *Server) Close() {
 			// previously-flaky tests) in the case of
 			// socket-late-binding races from the http Client
 			// dialing this server and then getting an idle
-			// connection before the dial completed.  There is thus
+			// connection before the dial completed. There is thus
 			// a connected connection in StateNew with no
 			// associated Request. We only close StateIdle and
 			// StateNew because they're not doing anything. It's
@@ -167,7 +167,7 @@ func (s *Server) Close() {
 			// few milliseconds wasn't liked (early versions of
 			// https://golang.org/cl/15151) so now we just
 			// forcefully close StateNew. The docs for Server.Close say
-			// we wait for "oustanding requests", so we don't close things
+			// we wait for "outstanding requests", so we don't close things
 			// in StateActive.
 			if st == http.StateIdle || st == http.StateNew {
 				s.closeConn(c)
@@ -202,12 +202,10 @@ func (s *Server) logCloseHangDebugInfo() {
 
 // CloseClientConnections closes any open HTTP connections to the test Server.
 func (s *Server) CloseClientConnections() {
-	var conns int
-	ch := make(chan bool)
-
 	s.mu.Lock()
+	nconn := len(s.conns)
+	ch := make(chan struct{}, nconn)
 	for c := range s.conns {
-		conns++
 		s.closeConnChan(c, ch)
 	}
 	s.mu.Unlock()
@@ -220,7 +218,7 @@ func (s *Server) CloseClientConnections() {
 	// in tests.
 	timer := time.NewTimer(5 * time.Second)
 	defer timer.Stop()
-	for i := 0; i < conns; i++ {
+	for i := 0; i < nconn; i++ {
 		select {
 		case <-ch:
 		case <-timer.C:
@@ -294,30 +292,20 @@ func (s *Server) closeConn(c net.Conn) { s.closeConnChan(c, nil) }
 
 // closeConnChan is like closeConn, but takes an optional channel to receive a value
 // when the goroutine closing c is done.
-func (s *Server) closeConnChan(c net.Conn, done chan<- bool) {
+func (s *Server) closeConnChan(c net.Conn, done chan<- struct{}) {
 	if runtime.GOOS == "plan9" {
 		// Go's Plan 9 net package isn't great at unblocking reads when
-		// their underlying TCP connections are closed.  Don't trust
+		// their underlying TCP connections are closed. Don't trust
 		// that that the ConnState state machine will get to
 		// StateClosed. Instead, just go there directly. Plan 9 may leak
 		// resources if the syscall doesn't end up returning. Oh well.
 		s.forgetConn(c)
 	}
 
-	// Somewhere in the chaos of https://golang.org/cl/15151 we found that
-	// some types of conns were blocking in Close too long (or deadlocking?)
-	// and we had to call Close in a goroutine. I (bradfitz) forget what
-	// that was at this point, but I suspect it was *tls.Conns, which
-	// were later fixed in https://golang.org/cl/18572, so this goroutine
-	// is _probably_ unnecessary now. But it's too late in Go 1.6 too remove
-	// it with confidence.
-	// TODO(bradfitz): try to remove it for Go 1.7. (golang.org/issue/14291)
-	go func() {
-		c.Close()
-		if done != nil {
-			done <- true
-		}
-	}()
+	c.Close()
+	if done != nil {
+		done <- struct{}{}
+	}
 }
 
 // forgetConn removes c from the set of tracked conns and decrements it from the
diff --git a/libgo/go/net/http/httptest/server_test.go b/libgo/go/net/http/httptest/server_test.go
index c9606f24198..d032c5983b7 100644
--- a/libgo/go/net/http/httptest/server_test.go
+++ b/libgo/go/net/http/httptest/server_test.go
@@ -53,7 +53,7 @@ func TestGetAfterClose(t *testing.T) {
 	res, err = http.Get(ts.URL)
 	if err == nil {
 		body, _ := ioutil.ReadAll(res.Body)
-		t.Fatalf("Unexected response after close: %v, %v, %s", res.Status, res.Header, body)
+		t.Fatalf("Unexpected response after close: %v, %v, %s", res.Status, res.Header, body)
 	}
 }
 
@@ -95,6 +95,6 @@ func TestServerCloseClientConnections(t *testing.T) {
 	res, err := http.Get(s.URL)
 	if err == nil {
 		res.Body.Close()
-		t.Fatal("Unexpected response: %#v", res)
+		t.Fatalf("Unexpected response: %#v", res)
 	}
 }
diff --git a/libgo/go/net/http/httptrace/trace.go b/libgo/go/net/http/httptrace/trace.go
new file mode 100644
index 00000000000..6f187a7b694
--- /dev/null
+++ b/libgo/go/net/http/httptrace/trace.go
@@ -0,0 +1,226 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.h
+
+// Package httptrace provides mechanisms to trace the events within
+// HTTP client requests.
+package httptrace
+
+import (
+	"context"
+	"internal/nettrace"
+	"net"
+	"reflect"
+	"time"
+)
+
+// unique type to prevent assignment.
+type clientEventContextKey struct{}
+
+// ContextClientTrace returns the ClientTrace associated with the
+// provided context. If none, it returns nil.
+func ContextClientTrace(ctx context.Context) *ClientTrace {
+	trace, _ := ctx.Value(clientEventContextKey{}).(*ClientTrace)
+	return trace
+}
+
+// WithClientTrace returns a new context based on the provided parent
+// ctx. HTTP client requests made with the returned context will use
+// the provided trace hooks, in addition to any previous hooks
+// registered with ctx. Any hooks defined in the provided trace will
+// be called first.
+func WithClientTrace(ctx context.Context, trace *ClientTrace) context.Context {
+	if trace == nil {
+		panic("nil trace")
+	}
+	old := ContextClientTrace(ctx)
+	trace.compose(old)
+
+	ctx = context.WithValue(ctx, clientEventContextKey{}, trace)
+	if trace.hasNetHooks() {
+		nt := &nettrace.Trace{
+			ConnectStart: trace.ConnectStart,
+			ConnectDone:  trace.ConnectDone,
+		}
+		if trace.DNSStart != nil {
+			nt.DNSStart = func(name string) {
+				trace.DNSStart(DNSStartInfo{Host: name})
+			}
+		}
+		if trace.DNSDone != nil {
+			nt.DNSDone = func(netIPs []interface{}, coalesced bool, err error) {
+				addrs := make([]net.IPAddr, len(netIPs))
+				for i, ip := range netIPs {
+					addrs[i] = ip.(net.IPAddr)
+				}
+				trace.DNSDone(DNSDoneInfo{
+					Addrs:     addrs,
+					Coalesced: coalesced,
+					Err:       err,
+				})
+			}
+		}
+		ctx = context.WithValue(ctx, nettrace.TraceKey{}, nt)
+	}
+	return ctx
+}
+
+// ClientTrace is a set of hooks to run at various stages of an HTTP
+// client request. Any particular hook may be nil. Functions may be
+// called concurrently from different goroutines, starting after the
+// call to Transport.RoundTrip and ending either when RoundTrip
+// returns an error, or when the Response.Body is closed.
+type ClientTrace struct {
+	// GetConn is called before a connection is created or
+	// retrieved from an idle pool. The hostPort is the
+	// "host:port" of the target or proxy. GetConn is called even
+	// if there's already an idle cached connection available.
+	GetConn func(hostPort string)
+
+	// GotConn is called after a successful connection is
+	// obtained. There is no hook for failure to obtain a
+	// connection; instead, use the error from
+	// Transport.RoundTrip.
+	GotConn func(GotConnInfo)
+
+	// PutIdleConn is called when the connection is returned to
+	// the idle pool. If err is nil, the connection was
+	// successfully returned to the idle pool. If err is non-nil,
+	// it describes why not. PutIdleConn is not called if
+	// connection reuse is disabled via Transport.DisableKeepAlives.
+	// PutIdleConn is called before the caller's Response.Body.Close
+	// call returns.
+	// For HTTP/2, this hook is not currently used.
+	PutIdleConn func(err error)
+
+	// GotFirstResponseByte is called when the first byte of the response
+	// headers is available.
+	GotFirstResponseByte func()
+
+	// Got100Continue is called if the server replies with a "100
+	// Continue" response.
+	Got100Continue func()
+
+	// DNSStart is called when a DNS lookup begins.
+	DNSStart func(DNSStartInfo)
+
+	// DNSDone is called when a DNS lookup ends.
+	DNSDone func(DNSDoneInfo)
+
+	// ConnectStart is called when a new connection's Dial begins.
+	// If net.Dialer.DualStack (IPv6 "Happy Eyeballs") support is
+	// enabled, this may be called multiple times.
+	ConnectStart func(network, addr string)
+
+	// ConnectDone is called when a new connection's Dial
+	// completes. The provided err indicates whether the
+	// connection completedly successfully.
+	// If net.Dialer.DualStack ("Happy Eyeballs") support is
+	// enabled, this may be called multiple times.
+	ConnectDone func(network, addr string, err error)
+
+	// WroteHeaders is called after the Transport has written
+	// the request headers.
+	WroteHeaders func()
+
+	// Wait100Continue is called if the Request specified
+	// "Expected: 100-continue" and the Transport has written the
+	// request headers but is waiting for "100 Continue" from the
+	// server before writing the request body.
+	Wait100Continue func()
+
+	// WroteRequest is called with the result of writing the
+	// request and any body.
+	WroteRequest func(WroteRequestInfo)
+}
+
+// WroteRequestInfo contains information provided to the WroteRequest
+// hook.
+type WroteRequestInfo struct {
+	// Err is any error encountered while writing the Request.
+	Err error
+}
+
+// compose modifies t such that it respects the previously-registered hooks in old,
+// subject to the composition policy requested in t.Compose.
+func (t *ClientTrace) compose(old *ClientTrace) {
+	if old == nil {
+		return
+	}
+	tv := reflect.ValueOf(t).Elem()
+	ov := reflect.ValueOf(old).Elem()
+	structType := tv.Type()
+	for i := 0; i < structType.NumField(); i++ {
+		tf := tv.Field(i)
+		hookType := tf.Type()
+		if hookType.Kind() != reflect.Func {
+			continue
+		}
+		of := ov.Field(i)
+		if of.IsNil() {
+			continue
+		}
+		if tf.IsNil() {
+			tf.Set(of)
+			continue
+		}
+
+		// Make a copy of tf for tf to call. (Otherwise it
+		// creates a recursive call cycle and stack overflows)
+		tfCopy := reflect.ValueOf(tf.Interface())
+
+		// We need to call both tf and of in some order.
+		newFunc := reflect.MakeFunc(hookType, func(args []reflect.Value) []reflect.Value {
+			tfCopy.Call(args)
+			return of.Call(args)
+		})
+		tv.Field(i).Set(newFunc)
+	}
+}
+
+// DNSStartInfo contains information about a DNS request.
+type DNSStartInfo struct {
+	Host string
+}
+
+// DNSDoneInfo contains information about the results of a DNS lookup.
+type DNSDoneInfo struct {
+	// Addrs are the IPv4 and/or IPv6 addresses found in the DNS
+	// lookup. The contents of the slice should not be mutated.
+	Addrs []net.IPAddr
+
+	// Err is any error that occurred during the DNS lookup.
+	Err error
+
+	// Coalesced is whether the Addrs were shared with another
+	// caller who was doing the same DNS lookup concurrently.
+	Coalesced bool
+}
+
+func (t *ClientTrace) hasNetHooks() bool {
+	if t == nil {
+		return false
+	}
+	return t.DNSStart != nil || t.DNSDone != nil || t.ConnectStart != nil || t.ConnectDone != nil
+}
+
+// GotConnInfo is the argument to the ClientTrace.GotConn function and
+// contains information about the obtained connection.
+type GotConnInfo struct {
+	// Conn is the connection that was obtained. It is owned by
+	// the http.Transport and should not be read, written or
+	// closed by users of ClientTrace.
+	Conn net.Conn
+
+	// Reused is whether this connection has been previously
+	// used for another HTTP request.
+	Reused bool
+
+	// WasIdle is whether this connection was obtained from an
+	// idle pool.
+	WasIdle bool
+
+	// IdleTime reports how long the connection was previously
+	// idle, if WasIdle is true.
+	IdleTime time.Duration
+}
diff --git a/libgo/go/net/http/httptrace/trace_test.go b/libgo/go/net/http/httptrace/trace_test.go
new file mode 100644
index 00000000000..c7eaed83d47
--- /dev/null
+++ b/libgo/go/net/http/httptrace/trace_test.go
@@ -0,0 +1,62 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.h
+
+package httptrace
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestCompose(t *testing.T) {
+	var buf bytes.Buffer
+	var testNum int
+
+	connectStart := func(b byte) func(network, addr string) {
+		return func(network, addr string) {
+			if addr != "addr" {
+				t.Errorf(`%d. args for %q case = %q, %q; want addr of "addr"`, testNum, b, network, addr)
+			}
+			buf.WriteByte(b)
+		}
+	}
+
+	tests := [...]struct {
+		trace, old *ClientTrace
+		want       string
+	}{
+		0: {
+			want: "T",
+			trace: &ClientTrace{
+				ConnectStart: connectStart('T'),
+			},
+		},
+		1: {
+			want: "TO",
+			trace: &ClientTrace{
+				ConnectStart: connectStart('T'),
+			},
+			old: &ClientTrace{ConnectStart: connectStart('O')},
+		},
+		2: {
+			want:  "O",
+			trace: &ClientTrace{},
+			old:   &ClientTrace{ConnectStart: connectStart('O')},
+		},
+	}
+	for i, tt := range tests {
+		testNum = i
+		buf.Reset()
+
+		tr := *tt.trace
+		tr.compose(tt.old)
+		if tr.ConnectStart != nil {
+			tr.ConnectStart("net", "addr")
+		}
+		if got := buf.String(); got != tt.want {
+			t.Errorf("%d. got = %q; want %q", i, got, tt.want)
+		}
+	}
+
+}
diff --git a/libgo/go/net/http/httputil/dump.go b/libgo/go/net/http/httputil/dump.go
index e22cc66dbfc..15116816328 100644
--- a/libgo/go/net/http/httputil/dump.go
+++ b/libgo/go/net/http/httputil/dump.go
@@ -128,7 +128,7 @@ func DumpRequestOut(req *http.Request, body bool) ([]byte, error) {
 
 	// If we used a dummy body above, remove it now.
 	// TODO: if the req.ContentLength is large, we allocate memory
-	// unnecessarily just to slice it off here.  But this is just
+	// unnecessarily just to slice it off here. But this is just
 	// a debug function, so this is acceptable for now. We could
 	// discard the body earlier if this matters.
 	if dummyBody {
@@ -163,18 +163,10 @@ func valueOrDefault(value, def string) string {
 
 var reqWriteExcludeHeaderDump = map[string]bool{
 	"Host":              true, // not in Header map anyway
-	"Content-Length":    true,
 	"Transfer-Encoding": true,
 	"Trailer":           true,
 }
 
-// dumpAsReceived writes req to w in the form as it was received, or
-// at least as accurately as possible from the information retained in
-// the request.
-func dumpAsReceived(req *http.Request, w io.Writer) error {
-	return nil
-}
-
 // DumpRequest returns the given request in its HTTP/1.x wire
 // representation. It should only be used by servers to debug client
 // requests. The returned representation is an approximation only;
@@ -191,7 +183,8 @@ func dumpAsReceived(req *http.Request, w io.Writer) error {
 //
 // The documentation for http.Request.Write details which fields
 // of req are included in the dump.
-func DumpRequest(req *http.Request, body bool) (dump []byte, err error) {
+func DumpRequest(req *http.Request, body bool) ([]byte, error) {
+	var err error
 	save := req.Body
 	if !body || req.Body == nil {
 		req.Body = nil
@@ -239,7 +232,7 @@ func DumpRequest(req *http.Request, body bool) (dump []byte, err error) {
 
 	err = req.Header.WriteSubset(&b, reqWriteExcludeHeaderDump)
 	if err != nil {
-		return
+		return nil, err
 	}
 
 	io.WriteString(&b, "\r\n")
@@ -258,35 +251,42 @@ func DumpRequest(req *http.Request, body bool) (dump []byte, err error) {
 
 	req.Body = save
 	if err != nil {
-		return
+		return nil, err
 	}
-	dump = b.Bytes()
-	return
+	return b.Bytes(), nil
 }
 
-// errNoBody is a sentinel error value used by failureToReadBody so we can detect
-// that the lack of body was intentional.
+// errNoBody is a sentinel error value used by failureToReadBody so we
+// can detect that the lack of body was intentional.
 var errNoBody = errors.New("sentinel error value")
 
 // failureToReadBody is a io.ReadCloser that just returns errNoBody on
-// Read.  It's swapped in when we don't actually want to consume the
-// body, but need a non-nil one, and want to distinguish the error
-// from reading the dummy body.
+// Read. It's swapped in when we don't actually want to consume
+// the body, but need a non-nil one, and want to distinguish the
+// error from reading the dummy body.
 type failureToReadBody struct{}
 
 func (failureToReadBody) Read([]byte) (int, error) { return 0, errNoBody }
 func (failureToReadBody) Close() error             { return nil }
 
+// emptyBody is an instance of empty reader.
 var emptyBody = ioutil.NopCloser(strings.NewReader(""))
 
 // DumpResponse is like DumpRequest but dumps a response.
-func DumpResponse(resp *http.Response, body bool) (dump []byte, err error) {
+func DumpResponse(resp *http.Response, body bool) ([]byte, error) {
 	var b bytes.Buffer
+	var err error
 	save := resp.Body
 	savecl := resp.ContentLength
 
 	if !body {
-		resp.Body = failureToReadBody{}
+		// For content length of zero. Make sure the body is an empty
+		// reader, instead of returning error through failureToReadBody{}.
+		if resp.ContentLength == 0 {
+			resp.Body = emptyBody
+		} else {
+			resp.Body = failureToReadBody{}
+		}
 	} else if resp.Body == nil {
 		resp.Body = emptyBody
 	} else {
diff --git a/libgo/go/net/http/httputil/dump_test.go b/libgo/go/net/http/httputil/dump_test.go
index 46bf521723a..2e980d39f8a 100644
--- a/libgo/go/net/http/httputil/dump_test.go
+++ b/libgo/go/net/http/httputil/dump_test.go
@@ -122,6 +122,10 @@ var dumpTests = []dumpTest{
 				Host:   "post.tld",
 				Path:   "/",
 			},
+			Header: http.Header{
+				"Content-Length": []string{"8193"},
+			},
+
 			ContentLength: 8193,
 			ProtoMajor:    1,
 			ProtoMinor:    1,
@@ -135,6 +139,10 @@ var dumpTests = []dumpTest{
 			"Content-Length: 8193\r\n" +
 			"Accept-Encoding: gzip\r\n\r\n" +
 			strings.Repeat("a", 8193),
+		WantDump: "POST / HTTP/1.1\r\n" +
+			"Host: post.tld\r\n" +
+			"Content-Length: 8193\r\n\r\n" +
+			strings.Repeat("a", 8193),
 	},
 
 	{
@@ -144,6 +152,38 @@ var dumpTests = []dumpTest{
 		WantDump: "GET http://foo.com/ HTTP/1.1\r\n" +
 			"User-Agent: blah\r\n\r\n",
 	},
+
+	// Issue #7215. DumpRequest should return the "Content-Length" when set
+	{
+		Req: *mustReadRequest("POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 3\r\n" +
+			"\r\nkey1=name1&key2=name2"),
+		WantDump: "POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 3\r\n" +
+			"\r\nkey",
+	},
+
+	// Issue #7215. DumpRequest should return the "Content-Length" in ReadRequest
+	{
+		Req: *mustReadRequest("POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 0\r\n" +
+			"\r\nkey1=name1&key2=name2"),
+		WantDump: "POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"Content-Length: 0\r\n\r\n",
+	},
+
+	// Issue #7215. DumpRequest should not return the "Content-Length" if unset
+	{
+		Req: *mustReadRequest("POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n" +
+			"\r\nkey1=name1&key2=name2"),
+		WantDump: "POST /v2/api/?login HTTP/1.1\r\n" +
+			"Host: passport.myhost.com\r\n\r\n",
+	},
 }
 
 func TestDumpRequest(t *testing.T) {
@@ -288,6 +328,27 @@ Transfer-Encoding: chunked
 foo
 0`,
 	},
+	{
+		res: &http.Response{
+			Status:        "200 OK",
+			StatusCode:    200,
+			Proto:         "HTTP/1.1",
+			ProtoMajor:    1,
+			ProtoMinor:    1,
+			ContentLength: 0,
+			Header: http.Header{
+				// To verify if headers are not filtered out.
+				"Foo1": []string{"Bar1"},
+				"Foo2": []string{"Bar2"},
+			},
+			Body: nil,
+		},
+		body: false, // to verify we see 0, not empty.
+		want: `HTTP/1.1 200 OK
+Foo1: Bar1
+Foo2: Bar2
+Content-Length: 0`,
+	},
 }
 
 func TestDumpResponse(t *testing.T) {
diff --git a/libgo/go/net/http/httputil/example_test.go b/libgo/go/net/http/httputil/example_test.go
index 8fb1a2d2792..e8dc962d3e3 100644
--- a/libgo/go/net/http/httputil/example_test.go
+++ b/libgo/go/net/http/httputil/example_test.go
@@ -49,7 +49,7 @@ func ExampleDumpRequest() {
 	fmt.Printf("%s", b)
 
 	// Output:
-	// "POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
+	// "POST / HTTP/1.1\r\nHost: www.example.org\r\nAccept-Encoding: gzip\r\nContent-Length: 75\r\nUser-Agent: Go-http-client/1.1\r\n\r\nGo is a general-purpose language designed with systems programming in mind."
 }
 
 func ExampleDumpRequestOut() {
diff --git a/libgo/go/net/http/httputil/persist.go b/libgo/go/net/http/httputil/persist.go
index 987bcc96ba1..87ddd52cd96 100644
--- a/libgo/go/net/http/httputil/persist.go
+++ b/libgo/go/net/http/httputil/persist.go
@@ -24,17 +24,13 @@ var (
 // ErrPersistEOF (above) reports that the remote side is closed.
 var errClosed = errors.New("i/o operation on closed connection")
 
-// A ServerConn reads requests and sends responses over an underlying
-// connection, until the HTTP keepalive logic commands an end. ServerConn
-// also allows hijacking the underlying connection by calling Hijack
-// to regain control over the connection. ServerConn supports pipe-lining,
-// i.e. requests can be read out of sync (but in the same order) while the
-// respective responses are sent.
+// ServerConn is an artifact of Go's early HTTP implementation.
+// It is low-level, old, and unused by Go's current HTTP stack.
+// We should have deleted it before Go 1.
 //
-// ServerConn is low-level and old. Applications should instead use Server
-// in the net/http package.
+// Deprecated: Use the Server in package net/http instead.
 type ServerConn struct {
-	lk              sync.Mutex // read-write protects the following fields
+	mu              sync.Mutex // read-write protects the following fields
 	c               net.Conn
 	r               *bufio.Reader
 	re, we          error // read/write errors
@@ -45,11 +41,11 @@ type ServerConn struct {
 	pipe textproto.Pipeline
 }
 
-// NewServerConn returns a new ServerConn reading and writing c. If r is not
-// nil, it is the buffer to use when reading c.
+// NewServerConn is an artifact of Go's early HTTP implementation.
+// It is low-level, old, and unused by Go's current HTTP stack.
+// We should have deleted it before Go 1.
 //
-// ServerConn is low-level and old. Applications should instead use Server
-// in the net/http package.
+// Deprecated: Use the Server in package net/http instead.
 func NewServerConn(c net.Conn, r *bufio.Reader) *ServerConn {
 	if r == nil {
 		r = bufio.NewReader(c)
@@ -61,17 +57,17 @@ func NewServerConn(c net.Conn, r *bufio.Reader) *ServerConn {
 // as the read-side bufio which may have some left over data. Hijack may be
 // called before Read has signaled the end of the keep-alive logic. The user
 // should not call Hijack while Read or Write is in progress.
-func (sc *ServerConn) Hijack() (c net.Conn, r *bufio.Reader) {
-	sc.lk.Lock()
-	defer sc.lk.Unlock()
-	c = sc.c
-	r = sc.r
+func (sc *ServerConn) Hijack() (net.Conn, *bufio.Reader) {
+	sc.mu.Lock()
+	defer sc.mu.Unlock()
+	c := sc.c
+	r := sc.r
 	sc.c = nil
 	sc.r = nil
-	return
+	return c, r
 }
 
-// Close calls Hijack and then also closes the underlying connection
+// Close calls Hijack and then also closes the underlying connection.
 func (sc *ServerConn) Close() error {
 	c, _ := sc.Hijack()
 	if c != nil {
@@ -84,7 +80,9 @@ func (sc *ServerConn) Close() error {
 // it is gracefully determined that there are no more requests (e.g. after the
 // first request on an HTTP/1.0 connection, or after a Connection:close on a
 // HTTP/1.1 connection).
-func (sc *ServerConn) Read() (req *http.Request, err error) {
+func (sc *ServerConn) Read() (*http.Request, error) {
+	var req *http.Request
+	var err error
 
 	// Ensure ordered execution of Reads and Writes
 	id := sc.pipe.Next()
@@ -96,29 +94,29 @@ func (sc *ServerConn) Read() (req *http.Request, err error) {
 			sc.pipe.EndResponse(id)
 		} else {
 			// Remember the pipeline id of this request
-			sc.lk.Lock()
+			sc.mu.Lock()
 			sc.pipereq[req] = id
-			sc.lk.Unlock()
+			sc.mu.Unlock()
 		}
 	}()
 
-	sc.lk.Lock()
+	sc.mu.Lock()
 	if sc.we != nil { // no point receiving if write-side broken or closed
-		defer sc.lk.Unlock()
+		defer sc.mu.Unlock()
 		return nil, sc.we
 	}
 	if sc.re != nil {
-		defer sc.lk.Unlock()
+		defer sc.mu.Unlock()
 		return nil, sc.re
 	}
 	if sc.r == nil { // connection closed by user in the meantime
-		defer sc.lk.Unlock()
+		defer sc.mu.Unlock()
 		return nil, errClosed
 	}
 	r := sc.r
 	lastbody := sc.lastbody
 	sc.lastbody = nil
-	sc.lk.Unlock()
+	sc.mu.Unlock()
 
 	// Make sure body is fully consumed, even if user does not call body.Close
 	if lastbody != nil {
@@ -127,16 +125,16 @@ func (sc *ServerConn) Read() (req *http.Request, err error) {
 		// returned.
 		err = lastbody.Close()
 		if err != nil {
-			sc.lk.Lock()
-			defer sc.lk.Unlock()
+			sc.mu.Lock()
+			defer sc.mu.Unlock()
 			sc.re = err
 			return nil, err
 		}
 	}
 
 	req, err = http.ReadRequest(r)
-	sc.lk.Lock()
-	defer sc.lk.Unlock()
+	sc.mu.Lock()
+	defer sc.mu.Unlock()
 	if err != nil {
 		if err == io.ErrUnexpectedEOF {
 			// A close from the opposing client is treated as a
@@ -161,8 +159,8 @@ func (sc *ServerConn) Read() (req *http.Request, err error) {
 // Pending returns the number of unanswered requests
 // that have been received on the connection.
 func (sc *ServerConn) Pending() int {
-	sc.lk.Lock()
-	defer sc.lk.Unlock()
+	sc.mu.Lock()
+	defer sc.mu.Unlock()
 	return sc.nread - sc.nwritten
 }
 
@@ -172,31 +170,31 @@ func (sc *ServerConn) Pending() int {
 func (sc *ServerConn) Write(req *http.Request, resp *http.Response) error {
 
 	// Retrieve the pipeline ID of this request/response pair
-	sc.lk.Lock()
+	sc.mu.Lock()
 	id, ok := sc.pipereq[req]
 	delete(sc.pipereq, req)
 	if !ok {
-		sc.lk.Unlock()
+		sc.mu.Unlock()
 		return ErrPipeline
 	}
-	sc.lk.Unlock()
+	sc.mu.Unlock()
 
 	// Ensure pipeline order
 	sc.pipe.StartResponse(id)
 	defer sc.pipe.EndResponse(id)
 
-	sc.lk.Lock()
+	sc.mu.Lock()
 	if sc.we != nil {
-		defer sc.lk.Unlock()
+		defer sc.mu.Unlock()
 		return sc.we
 	}
 	if sc.c == nil { // connection closed by user in the meantime
-		defer sc.lk.Unlock()
+		defer sc.mu.Unlock()
 		return ErrClosed
 	}
 	c := sc.c
 	if sc.nread <= sc.nwritten {
-		defer sc.lk.Unlock()
+		defer sc.mu.Unlock()
 		return errors.New("persist server pipe count")
 	}
 	if resp.Close {
@@ -205,11 +203,11 @@ func (sc *ServerConn) Write(req *http.Request, resp *http.Response) error {
 		// before signaling.
 		sc.re = ErrPersistEOF
 	}
-	sc.lk.Unlock()
+	sc.mu.Unlock()
 
 	err := resp.Write(c)
-	sc.lk.Lock()
-	defer sc.lk.Unlock()
+	sc.mu.Lock()
+	defer sc.mu.Unlock()
 	if err != nil {
 		sc.we = err
 		return err
@@ -219,15 +217,13 @@ func (sc *ServerConn) Write(req *http.Request, resp *http.Response) error {
 	return nil
 }
 
-// A ClientConn sends request and receives headers over an underlying
-// connection, while respecting the HTTP keepalive logic. ClientConn
-// supports hijacking the connection calling Hijack to
-// regain control of the underlying net.Conn and deal with it as desired.
+// ClientConn is an artifact of Go's early HTTP implementation.
+// It is low-level, old, and unused by Go's current HTTP stack.
+// We should have deleted it before Go 1.
 //
-// ClientConn is low-level and old. Applications should instead use
-// Client or Transport in the net/http package.
+// Deprecated: Use Client or Transport in package net/http instead.
 type ClientConn struct {
-	lk              sync.Mutex // read-write protects the following fields
+	mu              sync.Mutex // read-write protects the following fields
 	c               net.Conn
 	r               *bufio.Reader
 	re, we          error // read/write errors
@@ -239,11 +235,11 @@ type ClientConn struct {
 	writeReq func(*http.Request, io.Writer) error
 }
 
-// NewClientConn returns a new ClientConn reading and writing c.  If r is not
-// nil, it is the buffer to use when reading c.
+// NewClientConn is an artifact of Go's early HTTP implementation.
+// It is low-level, old, and unused by Go's current HTTP stack.
+// We should have deleted it before Go 1.
 //
-// ClientConn is low-level and old. Applications should use Client or
-// Transport in the net/http package.
+// Deprecated: Use the Client or Transport in package net/http instead.
 func NewClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
 	if r == nil {
 		r = bufio.NewReader(c)
@@ -256,11 +252,11 @@ func NewClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
 	}
 }
 
-// NewProxyClientConn works like NewClientConn but writes Requests
-// using Request's WriteProxy method.
+// NewProxyClientConn is an artifact of Go's early HTTP implementation.
+// It is low-level, old, and unused by Go's current HTTP stack.
+// We should have deleted it before Go 1.
 //
-// New code should not use NewProxyClientConn. See Client or
-// Transport in the net/http package instead.
+// Deprecated: Use the Client or Transport in package net/http instead.
 func NewProxyClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
 	cc := NewClientConn(c, r)
 	cc.writeReq = (*http.Request).WriteProxy
@@ -272,8 +268,8 @@ func NewProxyClientConn(c net.Conn, r *bufio.Reader) *ClientConn {
 // called before the user or Read have signaled the end of the keep-alive
 // logic. The user should not call Hijack while Read or Write is in progress.
 func (cc *ClientConn) Hijack() (c net.Conn, r *bufio.Reader) {
-	cc.lk.Lock()
-	defer cc.lk.Unlock()
+	cc.mu.Lock()
+	defer cc.mu.Unlock()
 	c = cc.c
 	r = cc.r
 	cc.c = nil
@@ -281,7 +277,7 @@ func (cc *ClientConn) Hijack() (c net.Conn, r *bufio.Reader) {
 	return
 }
 
-// Close calls Hijack and then also closes the underlying connection
+// Close calls Hijack and then also closes the underlying connection.
 func (cc *ClientConn) Close() error {
 	c, _ := cc.Hijack()
 	if c != nil {
@@ -295,7 +291,8 @@ func (cc *ClientConn) Close() error {
 // keepalive connection is logically closed after this request and the opposing
 // server is informed. An ErrUnexpectedEOF indicates the remote closed the
 // underlying TCP connection, which is usually considered as graceful close.
-func (cc *ClientConn) Write(req *http.Request) (err error) {
+func (cc *ClientConn) Write(req *http.Request) error {
+	var err error
 
 	// Ensure ordered execution of Writes
 	id := cc.pipe.Next()
@@ -307,23 +304,23 @@ func (cc *ClientConn) Write(req *http.Request) (err error) {
 			cc.pipe.EndResponse(id)
 		} else {
 			// Remember the pipeline id of this request
-			cc.lk.Lock()
+			cc.mu.Lock()
 			cc.pipereq[req] = id
-			cc.lk.Unlock()
+			cc.mu.Unlock()
 		}
 	}()
 
-	cc.lk.Lock()
+	cc.mu.Lock()
 	if cc.re != nil { // no point sending if read-side closed or broken
-		defer cc.lk.Unlock()
+		defer cc.mu.Unlock()
 		return cc.re
 	}
 	if cc.we != nil {
-		defer cc.lk.Unlock()
+		defer cc.mu.Unlock()
 		return cc.we
 	}
 	if cc.c == nil { // connection closed by user in the meantime
-		defer cc.lk.Unlock()
+		defer cc.mu.Unlock()
 		return errClosed
 	}
 	c := cc.c
@@ -332,11 +329,11 @@ func (cc *ClientConn) Write(req *http.Request) (err error) {
 		// still might be some pipelined reads
 		cc.we = ErrPersistEOF
 	}
-	cc.lk.Unlock()
+	cc.mu.Unlock()
 
 	err = cc.writeReq(req, c)
-	cc.lk.Lock()
-	defer cc.lk.Unlock()
+	cc.mu.Lock()
+	defer cc.mu.Unlock()
 	if err != nil {
 		cc.we = err
 		return err
@@ -349,8 +346,8 @@ func (cc *ClientConn) Write(req *http.Request) (err error) {
 // Pending returns the number of unanswered requests
 // that have been sent on the connection.
 func (cc *ClientConn) Pending() int {
-	cc.lk.Lock()
-	defer cc.lk.Unlock()
+	cc.mu.Lock()
+	defer cc.mu.Unlock()
 	return cc.nwritten - cc.nread
 }
 
@@ -360,32 +357,32 @@ func (cc *ClientConn) Pending() int {
 // concurrently with Write, but not with another Read.
 func (cc *ClientConn) Read(req *http.Request) (resp *http.Response, err error) {
 	// Retrieve the pipeline ID of this request/response pair
-	cc.lk.Lock()
+	cc.mu.Lock()
 	id, ok := cc.pipereq[req]
 	delete(cc.pipereq, req)
 	if !ok {
-		cc.lk.Unlock()
+		cc.mu.Unlock()
 		return nil, ErrPipeline
 	}
-	cc.lk.Unlock()
+	cc.mu.Unlock()
 
 	// Ensure pipeline order
 	cc.pipe.StartResponse(id)
 	defer cc.pipe.EndResponse(id)
 
-	cc.lk.Lock()
+	cc.mu.Lock()
 	if cc.re != nil {
-		defer cc.lk.Unlock()
+		defer cc.mu.Unlock()
 		return nil, cc.re
 	}
 	if cc.r == nil { // connection closed by user in the meantime
-		defer cc.lk.Unlock()
+		defer cc.mu.Unlock()
 		return nil, errClosed
 	}
 	r := cc.r
 	lastbody := cc.lastbody
 	cc.lastbody = nil
-	cc.lk.Unlock()
+	cc.mu.Unlock()
 
 	// Make sure body is fully consumed, even if user does not call body.Close
 	if lastbody != nil {
@@ -394,16 +391,16 @@ func (cc *ClientConn) Read(req *http.Request) (resp *http.Response, err error) {
 		// returned.
 		err = lastbody.Close()
 		if err != nil {
-			cc.lk.Lock()
-			defer cc.lk.Unlock()
+			cc.mu.Lock()
+			defer cc.mu.Unlock()
 			cc.re = err
 			return nil, err
 		}
 	}
 
 	resp, err = http.ReadResponse(r, req)
-	cc.lk.Lock()
-	defer cc.lk.Unlock()
+	cc.mu.Lock()
+	defer cc.mu.Unlock()
 	if err != nil {
 		cc.re = err
 		return resp, err
@@ -420,10 +417,10 @@ func (cc *ClientConn) Read(req *http.Request) (resp *http.Response, err error) {
 }
 
 // Do is convenience method that writes a request and reads a response.
-func (cc *ClientConn) Do(req *http.Request) (resp *http.Response, err error) {
-	err = cc.Write(req)
+func (cc *ClientConn) Do(req *http.Request) (*http.Response, error) {
+	err := cc.Write(req)
 	if err != nil {
-		return
+		return nil, err
 	}
 	return cc.Read(req)
 }
diff --git a/libgo/go/net/http/httputil/reverseproxy.go b/libgo/go/net/http/httputil/reverseproxy.go
index 54411caeca8..49c120afde1 100644
--- a/libgo/go/net/http/httputil/reverseproxy.go
+++ b/libgo/go/net/http/httputil/reverseproxy.go
@@ -90,6 +90,10 @@ func NewSingleHostReverseProxy(target *url.URL) *ReverseProxy {
 		} else {
 			req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
 		}
+		if _, ok := req.Header["User-Agent"]; !ok {
+			// explicitly disable User-Agent so it's not set to default value
+			req.Header.Set("User-Agent", "")
+		}
 	}
 	return &ReverseProxy{Director: director}
 }
@@ -180,9 +184,9 @@ func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	outreq.ProtoMinor = 1
 	outreq.Close = false
 
-	// Remove hop-by-hop headers to the backend.  Especially
+	// Remove hop-by-hop headers to the backend. Especially
 	// important is "Connection" because we want a persistent
-	// connection, regardless of what the client sent to us.  This
+	// connection, regardless of what the client sent to us. This
 	// is modifying the same underlying map from req (shallow
 	// copied above) so we only copy it if necessary.
 	copiedHeaders := false
@@ -210,7 +214,7 @@ func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	res, err := transport.RoundTrip(outreq)
 	if err != nil {
 		p.logf("http: proxy error: %v", err)
-		rw.WriteHeader(http.StatusInternalServerError)
+		rw.WriteHeader(http.StatusBadGateway)
 		return
 	}
 
@@ -285,13 +289,13 @@ type maxLatencyWriter struct {
 	dst     writeFlusher
 	latency time.Duration
 
-	lk   sync.Mutex // protects Write + Flush
+	mu   sync.Mutex // protects Write + Flush
 	done chan bool
 }
 
 func (m *maxLatencyWriter) Write(p []byte) (int, error) {
-	m.lk.Lock()
-	defer m.lk.Unlock()
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	return m.dst.Write(p)
 }
 
@@ -306,9 +310,9 @@ func (m *maxLatencyWriter) flushLoop() {
 			}
 			return
 		case <-t.C:
-			m.lk.Lock()
+			m.mu.Lock()
 			m.dst.Flush()
-			m.lk.Unlock()
+			m.mu.Unlock()
 		}
 	}
 }
diff --git a/libgo/go/net/http/httputil/reverseproxy_test.go b/libgo/go/net/http/httputil/reverseproxy_test.go
index 0849427b85c..fe7cdb888f5 100644
--- a/libgo/go/net/http/httputil/reverseproxy_test.go
+++ b/libgo/go/net/http/httputil/reverseproxy_test.go
@@ -33,6 +33,11 @@ func TestReverseProxy(t *testing.T) {
 	const backendResponse = "I am the backend"
 	const backendStatus = 404
 	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == "GET" && r.FormValue("mode") == "hangup" {
+			c, _, _ := w.(http.Hijacker).Hijack()
+			c.Close()
+			return
+		}
 		if len(r.TransferEncoding) > 0 {
 			t.Errorf("backend got unexpected TransferEncoding: %v", r.TransferEncoding)
 		}
@@ -69,6 +74,7 @@ func TestReverseProxy(t *testing.T) {
 		t.Fatal(err)
 	}
 	proxyHandler := NewSingleHostReverseProxy(backendURL)
+	proxyHandler.ErrorLog = log.New(ioutil.Discard, "", 0) // quiet for tests
 	frontend := httptest.NewServer(proxyHandler)
 	defer frontend.Close()
 
@@ -113,6 +119,20 @@ func TestReverseProxy(t *testing.T) {
 	if g, e := res.Trailer.Get("X-Trailer"), "trailer_value"; g != e {
 		t.Errorf("Trailer(X-Trailer) = %q ; want %q", g, e)
 	}
+
+	// Test that a backend failing to be reached or one which doesn't return
+	// a response results in a StatusBadGateway.
+	getReq, _ = http.NewRequest("GET", frontend.URL+"/?mode=hangup", nil)
+	getReq.Close = true
+	res, err = http.DefaultClient.Do(getReq)
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Body.Close()
+	if res.StatusCode != http.StatusBadGateway {
+		t.Errorf("request to bad proxy = %v; want 502 StatusBadGateway", res.Status)
+	}
+
 }
 
 func TestXForwardedFor(t *testing.T) {
@@ -328,6 +348,49 @@ func TestNilBody(t *testing.T) {
 	}
 }
 
+// Issue 15524
+func TestUserAgentHeader(t *testing.T) {
+	const explicitUA = "explicit UA"
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/noua" {
+			if c := r.Header.Get("User-Agent"); c != "" {
+				t.Errorf("handler got non-empty User-Agent header %q", c)
+			}
+			return
+		}
+		if c := r.Header.Get("User-Agent"); c != explicitUA {
+			t.Errorf("handler got unexpected User-Agent header %q", c)
+		}
+	}))
+	defer backend.Close()
+	backendURL, err := url.Parse(backend.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	proxyHandler := NewSingleHostReverseProxy(backendURL)
+	proxyHandler.ErrorLog = log.New(ioutil.Discard, "", 0) // quiet for tests
+	frontend := httptest.NewServer(proxyHandler)
+	defer frontend.Close()
+
+	getReq, _ := http.NewRequest("GET", frontend.URL, nil)
+	getReq.Header.Set("User-Agent", explicitUA)
+	getReq.Close = true
+	res, err := http.DefaultClient.Do(getReq)
+	if err != nil {
+		t.Fatalf("Get: %v", err)
+	}
+	res.Body.Close()
+
+	getReq, _ = http.NewRequest("GET", frontend.URL+"/noua", nil)
+	getReq.Header.Set("User-Agent", "")
+	getReq.Close = true
+	res, err = http.DefaultClient.Do(getReq)
+	if err != nil {
+		t.Fatalf("Get: %v", err)
+	}
+	res.Body.Close()
+}
+
 type bufferPool struct {
 	get func() []byte
 	put func([]byte)
diff --git a/libgo/go/net/http/internal/chunked_test.go b/libgo/go/net/http/internal/chunked_test.go
index a136dc99a65..9abe1ab6d9d 100644
--- a/libgo/go/net/http/internal/chunked_test.go
+++ b/libgo/go/net/http/internal/chunked_test.go
@@ -122,7 +122,7 @@ func TestChunkReaderAllocs(t *testing.T) {
 	byter := bytes.NewReader(buf.Bytes())
 	bufr := bufio.NewReader(byter)
 	mallocs := testing.AllocsPerRun(100, func() {
-		byter.Seek(0, 0)
+		byter.Seek(0, io.SeekStart)
 		bufr.Reset(byter)
 		r := NewChunkedReader(bufr)
 		n, err := io.ReadFull(r, readBuf)
diff --git a/libgo/go/net/http/lex.go b/libgo/go/net/http/lex.go
deleted file mode 100644
index 52b6481c14e..00000000000
--- a/libgo/go/net/http/lex.go
+++ /dev/null
@@ -1,183 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package http
-
-import (
-	"strings"
-	"unicode/utf8"
-)
-
-// This file deals with lexical matters of HTTP
-
-var isTokenTable = [127]bool{
-	'!':  true,
-	'#':  true,
-	'$':  true,
-	'%':  true,
-	'&':  true,
-	'\'': true,
-	'*':  true,
-	'+':  true,
-	'-':  true,
-	'.':  true,
-	'0':  true,
-	'1':  true,
-	'2':  true,
-	'3':  true,
-	'4':  true,
-	'5':  true,
-	'6':  true,
-	'7':  true,
-	'8':  true,
-	'9':  true,
-	'A':  true,
-	'B':  true,
-	'C':  true,
-	'D':  true,
-	'E':  true,
-	'F':  true,
-	'G':  true,
-	'H':  true,
-	'I':  true,
-	'J':  true,
-	'K':  true,
-	'L':  true,
-	'M':  true,
-	'N':  true,
-	'O':  true,
-	'P':  true,
-	'Q':  true,
-	'R':  true,
-	'S':  true,
-	'T':  true,
-	'U':  true,
-	'W':  true,
-	'V':  true,
-	'X':  true,
-	'Y':  true,
-	'Z':  true,
-	'^':  true,
-	'_':  true,
-	'`':  true,
-	'a':  true,
-	'b':  true,
-	'c':  true,
-	'd':  true,
-	'e':  true,
-	'f':  true,
-	'g':  true,
-	'h':  true,
-	'i':  true,
-	'j':  true,
-	'k':  true,
-	'l':  true,
-	'm':  true,
-	'n':  true,
-	'o':  true,
-	'p':  true,
-	'q':  true,
-	'r':  true,
-	's':  true,
-	't':  true,
-	'u':  true,
-	'v':  true,
-	'w':  true,
-	'x':  true,
-	'y':  true,
-	'z':  true,
-	'|':  true,
-	'~':  true,
-}
-
-func isToken(r rune) bool {
-	i := int(r)
-	return i < len(isTokenTable) && isTokenTable[i]
-}
-
-func isNotToken(r rune) bool {
-	return !isToken(r)
-}
-
-// headerValuesContainsToken reports whether any string in values
-// contains the provided token, ASCII case-insensitively.
-func headerValuesContainsToken(values []string, token string) bool {
-	for _, v := range values {
-		if headerValueContainsToken(v, token) {
-			return true
-		}
-	}
-	return false
-}
-
-// isOWS reports whether b is an optional whitespace byte, as defined
-// by RFC 7230 section 3.2.3.
-func isOWS(b byte) bool { return b == ' ' || b == '\t' }
-
-// trimOWS returns x with all optional whitespace removes from the
-// beginning and end.
-func trimOWS(x string) string {
-	// TODO: consider using strings.Trim(x, " \t") instead,
-	// if and when it's fast enough. See issue 10292.
-	// But this ASCII-only code will probably always beat UTF-8
-	// aware code.
-	for len(x) > 0 && isOWS(x[0]) {
-		x = x[1:]
-	}
-	for len(x) > 0 && isOWS(x[len(x)-1]) {
-		x = x[:len(x)-1]
-	}
-	return x
-}
-
-// headerValueContainsToken reports whether v (assumed to be a
-// 0#element, in the ABNF extension described in RFC 7230 section 7)
-// contains token amongst its comma-separated tokens, ASCII
-// case-insensitively.
-func headerValueContainsToken(v string, token string) bool {
-	v = trimOWS(v)
-	if comma := strings.IndexByte(v, ','); comma != -1 {
-		return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token)
-	}
-	return tokenEqual(v, token)
-}
-
-// lowerASCII returns the ASCII lowercase version of b.
-func lowerASCII(b byte) byte {
-	if 'A' <= b && b <= 'Z' {
-		return b + ('a' - 'A')
-	}
-	return b
-}
-
-// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.
-func tokenEqual(t1, t2 string) bool {
-	if len(t1) != len(t2) {
-		return false
-	}
-	for i, b := range t1 {
-		if b >= utf8.RuneSelf {
-			// No UTF-8 or non-ASCII allowed in tokens.
-			return false
-		}
-		if lowerASCII(byte(b)) != lowerASCII(t2[i]) {
-			return false
-		}
-	}
-	return true
-}
-
-// isLWS reports whether b is linear white space, according
-// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
-//      LWS            = [CRLF] 1*( SP | HT )
-func isLWS(b byte) bool { return b == ' ' || b == '\t' }
-
-// isCTL reports whether b is a control byte, according
-// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
-//      CTL            = <any US-ASCII control character
-//                       (octets 0 - 31) and DEL (127)>
-func isCTL(b byte) bool {
-	const del = 0x7f // a CTL
-	return b < ' ' || b == del
-}
diff --git a/libgo/go/net/http/main_test.go b/libgo/go/net/http/main_test.go
index 299cd7b2d2f..aea6e12744b 100644
--- a/libgo/go/net/http/main_test.go
+++ b/libgo/go/net/http/main_test.go
@@ -5,7 +5,6 @@
 package http_test
 
 import (
-	"flag"
 	"fmt"
 	"net/http"
 	"os"
@@ -16,8 +15,6 @@ import (
 	"time"
 )
 
-var flaky = flag.Bool("flaky", false, "run known-flaky tests too")
-
 func TestMain(m *testing.M) {
 	v := m.Run()
 	if v == 0 && goroutineLeaked() {
@@ -91,12 +88,6 @@ func setParallel(t *testing.T) {
 	}
 }
 
-func setFlaky(t *testing.T, issue int) {
-	if !*flaky {
-		t.Skipf("skipping known flaky test; see golang.org/issue/%d", issue)
-	}
-}
-
 func afterTest(t testing.TB) {
 	http.DefaultTransport.(*http.Transport).CloseIdleConnections()
 	if testing.Short() {
@@ -129,3 +120,17 @@ func afterTest(t testing.TB) {
 	}
 	t.Errorf("Test appears to have leaked %s:\n%s", bad, stacks)
 }
+
+// waitCondition reports whether fn eventually returned true,
+// checking immediately and then every checkEvery amount,
+// until waitFor has elapsed, at which point it returns false.
+func waitCondition(waitFor, checkEvery time.Duration, fn func() bool) bool {
+	deadline := time.Now().Add(waitFor)
+	for time.Now().Before(deadline) {
+		if fn() {
+			return true
+		}
+		time.Sleep(checkEvery)
+	}
+	return false
+}
diff --git a/libgo/go/net/http/method.go b/libgo/go/net/http/method.go
index b74f9604d34..6f46155069f 100644
--- a/libgo/go/net/http/method.go
+++ b/libgo/go/net/http/method.go
@@ -12,7 +12,7 @@ const (
 	MethodHead    = "HEAD"
 	MethodPost    = "POST"
 	MethodPut     = "PUT"
-	MethodPatch   = "PATCH" // RFC 5741
+	MethodPatch   = "PATCH" // RFC 5789
 	MethodDelete  = "DELETE"
 	MethodConnect = "CONNECT"
 	MethodOptions = "OPTIONS"
diff --git a/libgo/go/net/http/pprof/pprof.go b/libgo/go/net/http/pprof/pprof.go
index 7262c6c1016..05d0890fdf3 100644
--- a/libgo/go/net/http/pprof/pprof.go
+++ b/libgo/go/net/http/pprof/pprof.go
@@ -1,11 +1,9 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Package pprof serves via its HTTP server runtime profiling data
 // in the format expected by the pprof visualization tool.
-// For more information about pprof, see
-// http://code.google.com/p/google-perftools/.
 //
 // The package is typically only imported for the side effect of
 // registering its HTTP handlers.
@@ -15,7 +13,7 @@
 //	import _ "net/http/pprof"
 //
 // If your application is not already running an http server, you
-// need to start one.  Add "net/http" and "log" to your imports and
+// need to start one. Add "net/http" and "log" to your imports and
 // the following code to your main function:
 //
 // 	go func() {
@@ -30,7 +28,8 @@
 //
 //	go tool pprof http://localhost:6060/debug/pprof/profile
 //
-// Or to look at the goroutine blocking profile:
+// Or to look at the goroutine blocking profile, after calling
+// runtime.SetBlockProfileRate in your program:
 //
 //	go tool pprof http://localhost:6060/debug/pprof/block
 //
@@ -118,8 +117,8 @@ func Profile(w http.ResponseWriter, r *http.Request) {
 // Tracing lasts for duration specified in seconds GET parameter, or for 1 second if not specified.
 // The package initialization registers it as /debug/pprof/trace.
 func Trace(w http.ResponseWriter, r *http.Request) {
-	sec, _ := strconv.ParseInt(r.FormValue("seconds"), 10, 64)
-	if sec == 0 {
+	sec, err := strconv.ParseFloat(r.FormValue("seconds"), 64)
+	if sec <= 0 || err != nil {
 		sec = 1
 	}
 
@@ -127,18 +126,16 @@ func Trace(w http.ResponseWriter, r *http.Request) {
 	// because if it does it starts writing.
 	w.Header().Set("Content-Type", "application/octet-stream")
 	w.Write([]byte("tracing not yet supported with gccgo"))
-	/*
-		if err := trace.Start(w); err != nil {
-			// trace.Start failed, so no writes yet.
-			// Can change header back to text content and send error code.
-			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
-			w.WriteHeader(http.StatusInternalServerError)
-			fmt.Fprintf(w, "Could not enable tracing: %s\n", err)
-			return
-		}
-		sleep(w, time.Duration(sec)*time.Second)
-		trace.Stop()
-	*/
+	// if err := trace.Start(w); err != nil {
+	// 	// trace.Start failed, so no writes yet.
+	// 	// Can change header back to text content and send error code.
+	// 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	// 	w.WriteHeader(http.StatusInternalServerError)
+	// 	fmt.Fprintf(w, "Could not enable tracing: %s\n", err)
+	// 	return
+	// }
+	// sleep(w, time.Duration(sec*float64(time.Second)))
+	// trace.Stop()
 }
 
 // Symbol looks up the program counters listed in the request,
@@ -148,11 +145,11 @@ func Symbol(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
 
 	// We have to read the whole POST body before
-	// writing any output.  Buffer the output here.
+	// writing any output. Buffer the output here.
 	var buf bytes.Buffer
 
 	// We don't know how many symbols we have, but we
-	// do have symbol information.  Pprof only cares whether
+	// do have symbol information. Pprof only cares whether
 	// this number is 0 (no symbols available) or > 0.
 	fmt.Fprintf(&buf, "num_symbols: 1\n")
 
diff --git a/libgo/go/net/http/readrequest_test.go b/libgo/go/net/http/readrequest_test.go
index 60e2be41d17..4bf646b0a63 100644
--- a/libgo/go/net/http/readrequest_test.go
+++ b/libgo/go/net/http/readrequest_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -380,6 +380,27 @@ var reqTests = []reqTest{
 		noTrailer,
 		noError,
 	},
+
+	// http2 client preface:
+	{
+		"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n",
+		&Request{
+			Method: "PRI",
+			URL: &url.URL{
+				Path: "*",
+			},
+			Header:        Header{},
+			Proto:         "HTTP/2.0",
+			ProtoMajor:    2,
+			ProtoMinor:    0,
+			RequestURI:    "*",
+			ContentLength: -1,
+			Close:         true,
+		},
+		noBody,
+		noTrailer,
+		noError,
+	},
 }
 
 func TestReadRequest(t *testing.T) {
diff --git a/libgo/go/net/http/request.go b/libgo/go/net/http/request.go
index 8cdab02af5a..dc5559282d0 100644
--- a/libgo/go/net/http/request.go
+++ b/libgo/go/net/http/request.go
@@ -9,6 +9,7 @@ package http
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"crypto/tls"
 	"encoding/base64"
 	"errors"
@@ -17,6 +18,7 @@ import (
 	"io/ioutil"
 	"mime"
 	"mime/multipart"
+	"net/http/httptrace"
 	"net/textproto"
 	"net/url"
 	"strconv"
@@ -247,7 +249,52 @@ type Request struct {
 	// RoundTripper may support Cancel.
 	//
 	// For server requests, this field is not applicable.
+	//
+	// Deprecated: Use the Context and WithContext methods
+	// instead. If a Request's Cancel field and context are both
+	// set, it is undefined whether Cancel is respected.
 	Cancel <-chan struct{}
+
+	// Response is the redirect response which caused this request
+	// to be created. This field is only populated during client
+	// redirects.
+	Response *Response
+
+	// ctx is either the client or server context. It should only
+	// be modified via copying the whole Request using WithContext.
+	// It is unexported to prevent people from using Context wrong
+	// and mutating the contexts held by callers of the same request.
+	ctx context.Context
+}
+
+// Context returns the request's context. To change the context, use
+// WithContext.
+//
+// The returned context is always non-nil; it defaults to the
+// background context.
+//
+// For outgoing client requests, the context controls cancelation.
+//
+// For incoming server requests, the context is canceled when the
+// ServeHTTP method returns. For its associated values, see
+// ServerContextKey and LocalAddrContextKey.
+func (r *Request) Context() context.Context {
+	if r.ctx != nil {
+		return r.ctx
+	}
+	return context.Background()
+}
+
+// WithContext returns a shallow copy of r with its context changed
+// to ctx. The provided ctx must be non-nil.
+func (r *Request) WithContext(ctx context.Context) *Request {
+	if ctx == nil {
+		panic("nil context")
+	}
+	r2 := new(Request)
+	*r2 = *r
+	r2.ctx = ctx
+	return r2
 }
 
 // ProtoAtLeast reports whether the HTTP protocol used
@@ -279,8 +326,8 @@ func (r *Request) Cookie(name string) (*Cookie, error) {
 	return nil, ErrNoCookie
 }
 
-// AddCookie adds a cookie to the request.  Per RFC 6265 section 5.4,
-// AddCookie does not attach more than one Cookie header field.  That
+// AddCookie adds a cookie to the request. Per RFC 6265 section 5.4,
+// AddCookie does not attach more than one Cookie header field. That
 // means all cookies, if any, are written into the same line,
 // separated by semicolon.
 func (r *Request) AddCookie(c *Cookie) {
@@ -343,6 +390,12 @@ func (r *Request) multipartReader() (*multipart.Reader, error) {
 	return multipart.NewReader(r.Body, boundary), nil
 }
 
+// isH2Upgrade reports whether r represents the http2 "client preface"
+// magic string.
+func (r *Request) isH2Upgrade() bool {
+	return r.Method == "PRI" && len(r.Header) == 0 && r.URL.Path == "*" && r.Proto == "HTTP/2.0"
+}
+
 // Return value if nonempty, def otherwise.
 func valueOrDefault(value, def string) string {
 	if value != "" {
@@ -375,7 +428,7 @@ func (r *Request) Write(w io.Writer) error {
 }
 
 // WriteProxy is like Write but writes the request in the form
-// expected by an HTTP proxy.  In particular, WriteProxy writes the
+// expected by an HTTP proxy. In particular, WriteProxy writes the
 // initial Request-URI line of the request with an absolute URI, per
 // section 5.1.2 of RFC 2616, including the scheme and host.
 // In either case, WriteProxy also writes a Host header, using
@@ -390,7 +443,16 @@ var errMissingHost = errors.New("http: Request.Write on Request with no Host or
 
 // extraHeaders may be nil
 // waitForContinue may be nil
-func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, waitForContinue func() bool) error {
+func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, waitForContinue func() bool) (err error) {
+	trace := httptrace.ContextClientTrace(req.Context())
+	if trace != nil && trace.WroteRequest != nil {
+		defer func() {
+			trace.WroteRequest(httptrace.WroteRequestInfo{
+				Err: err,
+			})
+		}()
+	}
+
 	// Find the target host. Prefer the Host: header, but if that
 	// is not given, use the host from the request URL.
 	//
@@ -427,7 +489,7 @@ func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, wai
 		w = bw
 	}
 
-	_, err := fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(req.Method, "GET"), ruri)
+	_, err = fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(req.Method, "GET"), ruri)
 	if err != nil {
 		return err
 	}
@@ -478,6 +540,10 @@ func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, wai
 		return err
 	}
 
+	if trace != nil && trace.WroteHeaders != nil {
+		trace.WroteHeaders()
+	}
+
 	// Flush and wait for 100-continue if expected.
 	if waitForContinue != nil {
 		if bw, ok := w.(*bufio.Writer); ok {
@@ -486,7 +552,9 @@ func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, wai
 				return err
 			}
 		}
-
+		if trace != nil && trace.Wait100Continue != nil {
+			trace.Wait100Continue()
+		}
 		if !waitForContinue() {
 			req.closeBody()
 			return nil
@@ -521,7 +589,7 @@ func cleanHost(in string) string {
 	return in
 }
 
-// removeZone removes IPv6 zone identifer from host.
+// removeZone removes IPv6 zone identifier from host.
 // E.g., "[fe80::1%en0]:8080" to "[fe80::1]:8080"
 func removeZone(host string) string {
 	if !strings.HasPrefix(host, "[") {
@@ -613,6 +681,8 @@ func NewRequest(method, urlStr string, body io.Reader) (*Request, error) {
 	if !ok && body != nil {
 		rc = ioutil.NopCloser(body)
 	}
+	// The host's colon:port should be normalized. See Issue 14836.
+	u.Host = removeEmptyPort(u.Host)
 	req := &Request{
 		Method:     method,
 		URL:        u,
@@ -704,7 +774,9 @@ func putTextprotoReader(r *textproto.Reader) {
 }
 
 // ReadRequest reads and parses an incoming request from b.
-func ReadRequest(b *bufio.Reader) (req *Request, err error) { return readRequest(b, deleteHostHeader) }
+func ReadRequest(b *bufio.Reader) (*Request, error) {
+	return readRequest(b, deleteHostHeader)
+}
 
 // Constants for readRequest's deleteHostHeader parameter.
 const (
@@ -768,13 +840,13 @@ func readRequest(b *bufio.Reader, deleteHostHeader bool) (req *Request, err erro
 	}
 	req.Header = Header(mimeHeader)
 
-	// RFC2616: Must treat
+	// RFC 2616: Must treat
 	//	GET /index.html HTTP/1.1
 	//	Host: www.google.com
 	// and
 	//	GET http://www.google.com/index.html HTTP/1.1
 	//	Host: doesntmatter
-	// the same.  In the second case, any Host line is ignored.
+	// the same. In the second case, any Host line is ignored.
 	req.Host = req.URL.Host
 	if req.Host == "" {
 		req.Host = req.Header.get("Host")
@@ -792,6 +864,16 @@ func readRequest(b *bufio.Reader, deleteHostHeader bool) (req *Request, err erro
 		return nil, err
 	}
 
+	if req.isH2Upgrade() {
+		// Because it's neither chunked, nor declared:
+		req.ContentLength = -1
+
+		// We want to give handlers a chance to hijack the
+		// connection, but we need to prevent the Server from
+		// dealing with the connection further if it's not
+		// hijacked. Set Close to ensure that:
+		req.Close = true
+	}
 	return req, nil
 }
 
@@ -808,57 +890,56 @@ func MaxBytesReader(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser {
 }
 
 type maxBytesReader struct {
-	w       ResponseWriter
-	r       io.ReadCloser // underlying reader
-	n       int64         // max bytes remaining
-	stopped bool
-	sawEOF  bool
+	w   ResponseWriter
+	r   io.ReadCloser // underlying reader
+	n   int64         // max bytes remaining
+	err error         // sticky error
 }
 
 func (l *maxBytesReader) tooLarge() (n int, err error) {
-	if !l.stopped {
-		l.stopped = true
-		if res, ok := l.w.(*response); ok {
-			res.requestTooLarge()
-		}
-	}
-	return 0, errors.New("http: request body too large")
+	l.err = errors.New("http: request body too large")
+	return 0, l.err
 }
 
 func (l *maxBytesReader) Read(p []byte) (n int, err error) {
-	toRead := l.n
-	if l.n == 0 {
-		if l.sawEOF {
-			return l.tooLarge()
-		}
-		// The underlying io.Reader may not return (0, io.EOF)
-		// at EOF if the requested size is 0, so read 1 byte
-		// instead. The io.Reader docs are a bit ambiguous
-		// about the return value of Read when 0 bytes are
-		// requested, and {bytes,strings}.Reader gets it wrong
-		// too (it returns (0, nil) even at EOF).
-		toRead = 1
+	if l.err != nil {
+		return 0, l.err
 	}
-	if int64(len(p)) > toRead {
-		p = p[:toRead]
+	if len(p) == 0 {
+		return 0, nil
+	}
+	// If they asked for a 32KB byte read but only 5 bytes are
+	// remaining, no need to read 32KB. 6 bytes will answer the
+	// question of the whether we hit the limit or go past it.
+	if int64(len(p)) > l.n+1 {
+		p = p[:l.n+1]
 	}
 	n, err = l.r.Read(p)
-	if err == io.EOF {
-		l.sawEOF = true
-	}
-	if l.n == 0 {
-		// If we had zero bytes to read remaining (but hadn't seen EOF)
-		// and we get a byte here, that means we went over our limit.
-		if n > 0 {
-			return l.tooLarge()
-		}
-		return 0, err
+
+	if int64(n) <= l.n {
+		l.n -= int64(n)
+		l.err = err
+		return n, err
 	}
-	l.n -= int64(n)
-	if l.n < 0 {
-		l.n = 0
+
+	n = int(l.n)
+	l.n = 0
+
+	// The server code and client code both use
+	// maxBytesReader. This "requestTooLarge" check is
+	// only used by the server code. To prevent binaries
+	// which only using the HTTP Client code (such as
+	// cmd/go) from also linking in the HTTP server, don't
+	// use a static type assertion to the server
+	// "*response" type. Check this interface instead:
+	type requestTooLarger interface {
+		requestTooLarge()
 	}
-	return
+	if res, ok := l.w.(requestTooLarger); ok {
+		res.requestTooLarge()
+	}
+	l.err = errors.New("http: request body too large")
+	return n, l.err
 }
 
 func (l *maxBytesReader) Close() error {
@@ -995,9 +1076,16 @@ func (r *Request) ParseMultipartForm(maxMemory int64) error {
 	if err != nil {
 		return err
 	}
+
+	if r.PostForm == nil {
+		r.PostForm = make(url.Values)
+	}
 	for k, v := range f.Value {
 		r.Form[k] = append(r.Form[k], v...)
+		// r.PostForm should also be populated. See Issue 9305.
+		r.PostForm[k] = append(r.PostForm[k], v...)
 	}
+
 	r.MultipartForm = f
 
 	return nil
@@ -1086,92 +1174,3 @@ func (r *Request) isReplayable() bool {
 	}
 	return false
 }
-
-func validHostHeader(h string) bool {
-	// The latests spec is actually this:
-	//
-	// http://tools.ietf.org/html/rfc7230#section-5.4
-	//     Host = uri-host [ ":" port ]
-	//
-	// Where uri-host is:
-	//     http://tools.ietf.org/html/rfc3986#section-3.2.2
-	//
-	// But we're going to be much more lenient for now and just
-	// search for any byte that's not a valid byte in any of those
-	// expressions.
-	for i := 0; i < len(h); i++ {
-		if !validHostByte[h[i]] {
-			return false
-		}
-	}
-	return true
-}
-
-// See the validHostHeader comment.
-var validHostByte = [256]bool{
-	'0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true, '7': true,
-	'8': true, '9': true,
-
-	'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true, 'h': true,
-	'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true, 'o': true, 'p': true,
-	'q': true, 'r': true, 's': true, 't': true, 'u': true, 'v': true, 'w': true, 'x': true,
-	'y': true, 'z': true,
-
-	'A': true, 'B': true, 'C': true, 'D': true, 'E': true, 'F': true, 'G': true, 'H': true,
-	'I': true, 'J': true, 'K': true, 'L': true, 'M': true, 'N': true, 'O': true, 'P': true,
-	'Q': true, 'R': true, 'S': true, 'T': true, 'U': true, 'V': true, 'W': true, 'X': true,
-	'Y': true, 'Z': true,
-
-	'!':  true, // sub-delims
-	'$':  true, // sub-delims
-	'%':  true, // pct-encoded (and used in IPv6 zones)
-	'&':  true, // sub-delims
-	'(':  true, // sub-delims
-	')':  true, // sub-delims
-	'*':  true, // sub-delims
-	'+':  true, // sub-delims
-	',':  true, // sub-delims
-	'-':  true, // unreserved
-	'.':  true, // unreserved
-	':':  true, // IPv6address + Host expression's optional port
-	';':  true, // sub-delims
-	'=':  true, // sub-delims
-	'[':  true,
-	'\'': true, // sub-delims
-	']':  true,
-	'_':  true, // unreserved
-	'~':  true, // unreserved
-}
-
-func validHeaderName(v string) bool {
-	if len(v) == 0 {
-		return false
-	}
-	return strings.IndexFunc(v, isNotToken) == -1
-}
-
-// validHeaderValue reports whether v is a valid "field-value" according to
-// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2 :
-//
-//        message-header = field-name ":" [ field-value ]
-//        field-value    = *( field-content | LWS )
-//        field-content  = <the OCTETs making up the field-value
-//                         and consisting of either *TEXT or combinations
-//                         of token, separators, and quoted-string>
-//
-// http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 :
-//
-//        TEXT           = <any OCTET except CTLs,
-//                          but including LWS>
-//        LWS            = [CRLF] 1*( SP | HT )
-//        CTL            = <any US-ASCII control character
-//                         (octets 0 - 31) and DEL (127)>
-func validHeaderValue(v string) bool {
-	for i := 0; i < len(v); i++ {
-		b := v[i]
-		if isCTL(b) && !isLWS(b) {
-			return false
-		}
-	}
-	return true
-}
diff --git a/libgo/go/net/http/request_test.go b/libgo/go/net/http/request_test.go
index 0ecdf85a563..a4c88c02915 100644
--- a/libgo/go/net/http/request_test.go
+++ b/libgo/go/net/http/request_test.go
@@ -99,7 +99,7 @@ type parseContentTypeTest struct {
 
 var parseContentTypeTests = []parseContentTypeTest{
 	{false, stringMap{"Content-Type": {"text/plain"}}},
-	// Empty content type is legal - shoult be treated as
+	// Empty content type is legal - should be treated as
 	// application/octet-stream (RFC 2616, section 7.2.1)
 	{false, stringMap{}},
 	{true, stringMap{"Content-Type": {"text/plain; boundary="}}},
@@ -158,6 +158,68 @@ func TestMultipartReader(t *testing.T) {
 	}
 }
 
+// Issue 9305: ParseMultipartForm should populate PostForm too
+func TestParseMultipartFormPopulatesPostForm(t *testing.T) {
+	postData :=
+		`--xxx
+Content-Disposition: form-data; name="field1"
+
+value1
+--xxx
+Content-Disposition: form-data; name="field2"
+
+value2
+--xxx
+Content-Disposition: form-data; name="file"; filename="file"
+Content-Type: application/octet-stream
+Content-Transfer-Encoding: binary
+
+binary data
+--xxx--
+`
+	req := &Request{
+		Method: "POST",
+		Header: Header{"Content-Type": {`multipart/form-data; boundary=xxx`}},
+		Body:   ioutil.NopCloser(strings.NewReader(postData)),
+	}
+
+	initialFormItems := map[string]string{
+		"language": "Go",
+		"name":     "gopher",
+		"skill":    "go-ing",
+		"field2":   "initial-value2",
+	}
+
+	req.Form = make(url.Values)
+	for k, v := range initialFormItems {
+		req.Form.Add(k, v)
+	}
+
+	err := req.ParseMultipartForm(10000)
+	if err != nil {
+		t.Fatalf("unexpected multipart error %v", err)
+	}
+
+	wantForm := url.Values{
+		"language": []string{"Go"},
+		"name":     []string{"gopher"},
+		"skill":    []string{"go-ing"},
+		"field1":   []string{"value1"},
+		"field2":   []string{"initial-value2", "value2"},
+	}
+	if !reflect.DeepEqual(req.Form, wantForm) {
+		t.Fatalf("req.Form = %v, want %v", req.Form, wantForm)
+	}
+
+	wantPostForm := url.Values{
+		"field1": []string{"value1"},
+		"field2": []string{"value2"},
+	}
+	if !reflect.DeepEqual(req.PostForm, wantPostForm) {
+		t.Fatalf("req.PostForm = %v, want %v", req.PostForm, wantPostForm)
+	}
+}
+
 func TestParseMultipartForm(t *testing.T) {
 	req := &Request{
 		Method: "POST",
@@ -336,11 +398,13 @@ var newRequestHostTests = []struct {
 
 	{"http://192.168.0.1/", "192.168.0.1"},
 	{"http://192.168.0.1:8080/", "192.168.0.1:8080"},
+	{"http://192.168.0.1:/", "192.168.0.1"},
 
 	{"http://[fe80::1]/", "[fe80::1]"},
 	{"http://[fe80::1]:8080/", "[fe80::1]:8080"},
 	{"http://[fe80::1%25en0]/", "[fe80::1%en0]"},
 	{"http://[fe80::1%25en0]:8080/", "[fe80::1%en0]:8080"},
+	{"http://[fe80::1%25en0]:/", "[fe80::1%en0]"},
 }
 
 func TestNewRequestHost(t *testing.T) {
@@ -615,6 +679,46 @@ func TestIssue10884_MaxBytesEOF(t *testing.T) {
 	}
 }
 
+// Issue 14981: MaxBytesReader's return error wasn't sticky. It
+// doesn't technically need to be, but people expected it to be.
+func TestMaxBytesReaderStickyError(t *testing.T) {
+	isSticky := func(r io.Reader) error {
+		var log bytes.Buffer
+		buf := make([]byte, 1000)
+		var firstErr error
+		for {
+			n, err := r.Read(buf)
+			fmt.Fprintf(&log, "Read(%d) = %d, %v\n", len(buf), n, err)
+			if err == nil {
+				continue
+			}
+			if firstErr == nil {
+				firstErr = err
+				continue
+			}
+			if !reflect.DeepEqual(err, firstErr) {
+				return fmt.Errorf("non-sticky error. got log:\n%s", log.Bytes())
+			}
+			t.Logf("Got log: %s", log.Bytes())
+			return nil
+		}
+	}
+	tests := [...]struct {
+		readable int
+		limit    int64
+	}{
+		0: {99, 100},
+		1: {100, 100},
+		2: {101, 100},
+	}
+	for i, tt := range tests {
+		rc := MaxBytesReader(nil, ioutil.NopCloser(bytes.NewReader(make([]byte, tt.readable))), tt.limit)
+		if err := isSticky(rc); err != nil {
+			t.Errorf("%d. error: %v", i, err)
+		}
+	}
+}
+
 func testMissingFile(t *testing.T, req *Request) {
 	f, fh, err := req.FormFile("missing")
 	if f != nil {
diff --git a/libgo/go/net/http/requestwrite_test.go b/libgo/go/net/http/requestwrite_test.go
index cfb95b0a800..2545f6f4c22 100644
--- a/libgo/go/net/http/requestwrite_test.go
+++ b/libgo/go/net/http/requestwrite_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -573,7 +573,7 @@ func TestRequestWriteClosesBody(t *testing.T) {
 		"Transfer-Encoding: chunked\r\n\r\n" +
 		// TODO: currently we don't buffer before chunking, so we get a
 		// single "m" chunk before the other chunks, as this was the 1-byte
-		// read from our MultiReader where we stiched the Body back together
+		// read from our MultiReader where we stitched the Body back together
 		// after sniffing whether the Body was 0 bytes or not.
 		chunk("m") +
 		chunk("y body") +
@@ -604,7 +604,7 @@ func TestRequestWriteError(t *testing.T) {
 	failAfter, writeCount := 0, 0
 	errFail := errors.New("fake write failure")
 
-	// w is the buffered io.Writer to write the request to.  It
+	// w is the buffered io.Writer to write the request to. It
 	// fails exactly once on its Nth Write call, as controlled by
 	// failAfter. It also tracks the number of calls in
 	// writeCount.
diff --git a/libgo/go/net/http/response.go b/libgo/go/net/http/response.go
index c424f61cd00..5450d50c3ce 100644
--- a/libgo/go/net/http/response.go
+++ b/libgo/go/net/http/response.go
@@ -11,6 +11,7 @@ import (
 	"bytes"
 	"crypto/tls"
 	"errors"
+	"fmt"
 	"io"
 	"net/textproto"
 	"net/url"
@@ -33,7 +34,7 @@ type Response struct {
 	ProtoMajor int    // e.g. 1
 	ProtoMinor int    // e.g. 0
 
-	// Header maps header keys to values.  If the response had multiple
+	// Header maps header keys to values. If the response had multiple
 	// headers with the same key, they may be concatenated, with comma
 	// delimiters.  (Section 4.2 of RFC 2616 requires that multiple headers
 	// be semantically equivalent to a comma-delimited sequence.) Values
@@ -57,8 +58,8 @@ type Response struct {
 	// with a "chunked" Transfer-Encoding.
 	Body io.ReadCloser
 
-	// ContentLength records the length of the associated content.  The
-	// value -1 indicates that the length is unknown.  Unless Request.Method
+	// ContentLength records the length of the associated content. The
+	// value -1 indicates that the length is unknown. Unless Request.Method
 	// is "HEAD", values >= 0 indicate that the given number of bytes may
 	// be read from Body.
 	ContentLength int64
@@ -68,10 +69,19 @@ type Response struct {
 	TransferEncoding []string
 
 	// Close records whether the header directed that the connection be
-	// closed after reading Body.  The value is advice for clients: neither
+	// closed after reading Body. The value is advice for clients: neither
 	// ReadResponse nor Response.Write ever closes a connection.
 	Close bool
 
+	// Uncompressed reports whether the response was sent compressed but
+	// was decompressed by the http package. When true, reading from
+	// Body yields the uncompressed content instead of the compressed
+	// content actually set from the server, ContentLength is set to -1,
+	// and the "Content-Length" and "Content-Encoding" fields are deleted
+	// from the responseHeader. To get the original response from
+	// the server, set Transport.DisableCompression to true.
+	Uncompressed bool
+
 	// Trailer maps trailer keys to values in the same
 	// format as Header.
 	//
@@ -86,7 +96,7 @@ type Response struct {
 	// any trailer values sent by the server.
 	Trailer Header
 
-	// The Request that was sent to obtain this Response.
+	// Request is the request that was sent to obtain this Response.
 	// Request's Body is nil (having already been consumed).
 	// This is only populated for Client requests.
 	Request *Request
@@ -108,8 +118,8 @@ func (r *Response) Cookies() []*Cookie {
 var ErrNoLocation = errors.New("http: no Location header in response")
 
 // Location returns the URL of the response's "Location" header,
-// if present.  Relative redirects are resolved relative to
-// the Response's Request.  ErrNoLocation is returned if no
+// if present. Relative redirects are resolved relative to
+// the Response's Request. ErrNoLocation is returned if no
 // Location header is present.
 func (r *Response) Location() (*url.URL, error) {
 	lv := r.Header.Get("Location")
@@ -184,7 +194,7 @@ func ReadResponse(r *bufio.Reader, req *Request) (*Response, error) {
 	return resp, nil
 }
 
-// RFC2616: Should treat
+// RFC 2616: Should treat
 //	Pragma: no-cache
 // like
 //	Cache-Control: no-cache
@@ -203,7 +213,7 @@ func (r *Response) ProtoAtLeast(major, minor int) bool {
 		r.ProtoMajor == major && r.ProtoMinor >= minor
 }
 
-// Write writes r to w in the HTTP/1.n server response format,
+// Write writes r to w in the HTTP/1.x server response format,
 // including the status line, headers, body, and optional trailer.
 //
 // This method consults the following fields of the response r:
@@ -228,11 +238,13 @@ func (r *Response) Write(w io.Writer) error {
 		if !ok {
 			text = "status code " + strconv.Itoa(r.StatusCode)
 		}
+	} else {
+		// Just to reduce stutter, if user set r.Status to "200 OK" and StatusCode to 200.
+		// Not important.
+		text = strings.TrimPrefix(text, strconv.Itoa(r.StatusCode)+" ")
 	}
-	protoMajor, protoMinor := strconv.Itoa(r.ProtoMajor), strconv.Itoa(r.ProtoMinor)
-	statusCode := strconv.Itoa(r.StatusCode) + " "
-	text = strings.TrimPrefix(text, statusCode)
-	if _, err := io.WriteString(w, "HTTP/"+protoMajor+"."+protoMinor+" "+statusCode+text+"\r\n"); err != nil {
+
+	if _, err := fmt.Fprintf(w, "HTTP/%d.%d %03d %s\r\n", r.ProtoMajor, r.ProtoMinor, r.StatusCode, text); err != nil {
 		return err
 	}
 
@@ -265,7 +277,7 @@ func (r *Response) Write(w io.Writer) error {
 	// content-length, the only way to do that is the old HTTP/1.0
 	// way, by noting the EOF with a connection close, so we need
 	// to set Close.
-	if r1.ContentLength == -1 && !r1.Close && r1.ProtoAtLeast(1, 1) && !chunked(r1.TransferEncoding) {
+	if r1.ContentLength == -1 && !r1.Close && r1.ProtoAtLeast(1, 1) && !chunked(r1.TransferEncoding) && !r1.Uncompressed {
 		r1.Close = true
 	}
 
diff --git a/libgo/go/net/http/response_test.go b/libgo/go/net/http/response_test.go
index d8a53400cf2..126da927355 100644
--- a/libgo/go/net/http/response_test.go
+++ b/libgo/go/net/http/response_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -10,6 +10,7 @@ import (
 	"compress/gzip"
 	"crypto/rand"
 	"fmt"
+	"go/ast"
 	"io"
 	"io/ioutil"
 	"net/http/internal"
@@ -505,6 +506,32 @@ some body`,
 
 		"Body here\n",
 	},
+
+	{
+		"HTTP/1.1 200 OK\r\n" +
+			"Content-Encoding: gzip\r\n" +
+			"Content-Length: 23\r\n" +
+			"Connection: keep-alive\r\n" +
+			"Keep-Alive: timeout=7200\r\n\r\n" +
+			"\x1f\x8b\b\x00\x00\x00\x00\x00\x00\x00s\xf3\xf7\a\x00\xab'\xd4\x1a\x03\x00\x00\x00",
+		Response{
+			Status:     "200 OK",
+			StatusCode: 200,
+			Proto:      "HTTP/1.1",
+			ProtoMajor: 1,
+			ProtoMinor: 1,
+			Request:    dummyReq("GET"),
+			Header: Header{
+				"Content-Length":   {"23"},
+				"Content-Encoding": {"gzip"},
+				"Connection":       {"keep-alive"},
+				"Keep-Alive":       {"timeout=7200"},
+			},
+			Close:         false,
+			ContentLength: 23,
+		},
+		"\x1f\x8b\b\x00\x00\x00\x00\x00\x00\x00s\xf3\xf7\a\x00\xab'\xd4\x1a\x03\x00\x00\x00",
+	},
 }
 
 // tests successful calls to ReadResponse, and inspects the returned Response.
@@ -656,10 +683,14 @@ func diff(t *testing.T, prefix string, have, want interface{}) {
 		t.Errorf("%s: type mismatch %v want %v", prefix, hv.Type(), wv.Type())
 	}
 	for i := 0; i < hv.NumField(); i++ {
+		name := hv.Type().Field(i).Name
+		if !ast.IsExported(name) {
+			continue
+		}
 		hf := hv.Field(i).Interface()
 		wf := wv.Field(i).Interface()
 		if !reflect.DeepEqual(hf, wf) {
-			t.Errorf("%s: %s = %v want %v", prefix, hv.Type().Field(i).Name, hf, wf)
+			t.Errorf("%s: %s = %v want %v", prefix, name, hf, wf)
 		}
 	}
 }
diff --git a/libgo/go/net/http/responsewrite_test.go b/libgo/go/net/http/responsewrite_test.go
index 5b8d47ab581..90f6767d96b 100644
--- a/libgo/go/net/http/responsewrite_test.go
+++ b/libgo/go/net/http/responsewrite_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -222,6 +222,39 @@ func TestResponseWrite(t *testing.T) {
 			},
 			"HTTP/1.1 200 OK\r\nConnection: close\r\n\r\nabcdef",
 		},
+
+		// Status code under 100 should be zero-padded to
+		// three digits.  Still bogus, but less bogus. (be
+		// consistent with generating three digits, since the
+		// Transport requires it)
+		{
+			Response{
+				StatusCode: 7,
+				Status:     "license to violate specs",
+				ProtoMajor: 1,
+				ProtoMinor: 0,
+				Request:    dummyReq("GET"),
+				Header:     Header{},
+				Body:       nil,
+			},
+
+			"HTTP/1.0 007 license to violate specs\r\nContent-Length: 0\r\n\r\n",
+		},
+
+		// No stutter.
+		{
+			Response{
+				StatusCode: 123,
+				Status:     "123 Sesame Street",
+				ProtoMajor: 1,
+				ProtoMinor: 0,
+				Request:    dummyReq("GET"),
+				Header:     Header{},
+				Body:       nil,
+			},
+
+			"HTTP/1.0 123 Sesame Street\r\nContent-Length: 0\r\n\r\n",
+		},
 	}
 
 	for i := range respWriteTests {
diff --git a/libgo/go/net/http/serve_test.go b/libgo/go/net/http/serve_test.go
index 384b453ce0a..139ce3eafc7 100644
--- a/libgo/go/net/http/serve_test.go
+++ b/libgo/go/net/http/serve_test.go
@@ -9,7 +9,10 @@ package http_test
 import (
 	"bufio"
 	"bytes"
+	"compress/gzip"
+	"context"
 	"crypto/tls"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"internal/testenv"
@@ -617,7 +620,7 @@ func TestIdentityResponse(t *testing.T) {
 	defer ts.Close()
 
 	// Note: this relies on the assumption (which is true) that
-	// Get sends HTTP/1.1 or greater requests.  Otherwise the
+	// Get sends HTTP/1.1 or greater requests. Otherwise the
 	// server wouldn't have the choice to send back chunked
 	// responses.
 	for _, te := range []string{"", "identity"} {
@@ -713,6 +716,31 @@ func testTCPConnectionCloses(t *testing.T, req string, h Handler) {
 	}
 }
 
+func testTCPConnectionStaysOpen(t *testing.T, req string, handler Handler) {
+	defer afterTest(t)
+	ts := httptest.NewServer(handler)
+	defer ts.Close()
+	conn, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+	br := bufio.NewReader(conn)
+	for i := 0; i < 2; i++ {
+		if _, err := io.WriteString(conn, req); err != nil {
+			t.Fatal(err)
+		}
+		res, err := ReadResponse(br, nil)
+		if err != nil {
+			t.Fatalf("res %d: %v", i+1, err)
+		}
+		if _, err := io.Copy(ioutil.Discard, res.Body); err != nil {
+			t.Fatalf("res %d body copy: %v", i+1, err)
+		}
+		res.Body.Close()
+	}
+}
+
 // TestServeHTTP10Close verifies that HTTP/1.0 requests won't be kept alive.
 func TestServeHTTP10Close(t *testing.T) {
 	testTCPConnectionCloses(t, "GET / HTTP/1.0\r\n\r\n", HandlerFunc(func(w ResponseWriter, r *Request) {
@@ -741,6 +769,61 @@ func TestHandlersCanSetConnectionClose10(t *testing.T) {
 	}))
 }
 
+func TestHTTP2UpgradeClosesConnection(t *testing.T) {
+	testTCPConnectionCloses(t, "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n", HandlerFunc(func(w ResponseWriter, r *Request) {
+		// Nothing. (if not hijacked, the server should close the connection
+		// afterwards)
+	}))
+}
+
+func send204(w ResponseWriter, r *Request) { w.WriteHeader(204) }
+func send304(w ResponseWriter, r *Request) { w.WriteHeader(304) }
+
+// Issue 15647: 204 responses can't have bodies, so HTTP/1.0 keep-alive conns should stay open.
+func TestHTTP10KeepAlive204Response(t *testing.T) {
+	testTCPConnectionStaysOpen(t, "GET / HTTP/1.0\r\nConnection: keep-alive\r\n\r\n", HandlerFunc(send204))
+}
+
+func TestHTTP11KeepAlive204Response(t *testing.T) {
+	testTCPConnectionStaysOpen(t, "GET / HTTP/1.1\r\nHost: foo\r\n\r\n", HandlerFunc(send204))
+}
+
+func TestHTTP10KeepAlive304Response(t *testing.T) {
+	testTCPConnectionStaysOpen(t,
+		"GET / HTTP/1.0\r\nConnection: keep-alive\r\nIf-Modified-Since: Mon, 02 Jan 2006 15:04:05 GMT\r\n\r\n",
+		HandlerFunc(send304))
+}
+
+// Issue 15703
+func TestKeepAliveFinalChunkWithEOF(t *testing.T) {
+	defer afterTest(t)
+	cst := newClientServerTest(t, false /* h1 */, HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.(Flusher).Flush() // force chunked encoding
+		w.Write([]byte("{\"Addr\": \"" + r.RemoteAddr + "\"}"))
+	}))
+	defer cst.close()
+	type data struct {
+		Addr string
+	}
+	var addrs [2]data
+	for i := range addrs {
+		res, err := cst.c.Get(cst.ts.URL)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := json.NewDecoder(res.Body).Decode(&addrs[i]); err != nil {
+			t.Fatal(err)
+		}
+		if addrs[i].Addr == "" {
+			t.Fatal("no address")
+		}
+		res.Body.Close()
+	}
+	if addrs[0] != addrs[1] {
+		t.Fatalf("connection not reused")
+	}
+}
+
 func TestSetsRemoteAddr_h1(t *testing.T) { testSetsRemoteAddr(t, h1Mode) }
 func TestSetsRemoteAddr_h2(t *testing.T) { testSetsRemoteAddr(t, h2Mode) }
 
@@ -984,7 +1067,7 @@ func TestTLSServer(t *testing.T) {
 	defer ts.Close()
 
 	// Connect an idle TCP connection to this server before we run
-	// our real tests.  This idle connection used to block forever
+	// our real tests. This idle connection used to block forever
 	// in the TLS handshake, preventing future connections from
 	// being accepted. It may prevent future accidental blocking
 	// in newConn.
@@ -1024,11 +1107,44 @@ func TestTLSServer(t *testing.T) {
 	})
 }
 
-func TestAutomaticHTTP2_Serve(t *testing.T) {
+// Issue 15908
+func TestAutomaticHTTP2_Serve_NoTLSConfig(t *testing.T) {
+	testAutomaticHTTP2_Serve(t, nil, true)
+}
+
+func TestAutomaticHTTP2_Serve_NonH2TLSConfig(t *testing.T) {
+	testAutomaticHTTP2_Serve(t, &tls.Config{}, false)
+}
+
+func TestAutomaticHTTP2_Serve_H2TLSConfig(t *testing.T) {
+	testAutomaticHTTP2_Serve(t, &tls.Config{NextProtos: []string{"h2"}}, true)
+}
+
+func testAutomaticHTTP2_Serve(t *testing.T, tlsConf *tls.Config, wantH2 bool) {
 	defer afterTest(t)
 	ln := newLocalListener(t)
 	ln.Close() // immediately (not a defer!)
 	var s Server
+	s.TLSConfig = tlsConf
+	if err := s.Serve(ln); err == nil {
+		t.Fatal("expected an error")
+	}
+	gotH2 := s.TLSNextProto["h2"] != nil
+	if gotH2 != wantH2 {
+		t.Errorf("http2 configured = %v; want %v", gotH2, wantH2)
+	}
+}
+
+func TestAutomaticHTTP2_Serve_WithTLSConfig(t *testing.T) {
+	defer afterTest(t)
+	ln := newLocalListener(t)
+	ln.Close() // immediately (not a defer!)
+	var s Server
+	// Set the TLSConfig. In reality, this would be the
+	// *tls.Config given to tls.NewListener.
+	s.TLSConfig = &tls.Config{
+		NextProtos: []string{"h2"},
+	}
 	if err := s.Serve(ln); err == nil {
 		t.Fatal("expected an error")
 	}
@@ -1888,6 +2004,52 @@ func TestTimeoutHandlerRaceHeaderTimeout(t *testing.T) {
 	}
 }
 
+// Issue 14568.
+func TestTimeoutHandlerStartTimerWhenServing(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping sleeping test in -short mode")
+	}
+	defer afterTest(t)
+	var handler HandlerFunc = func(w ResponseWriter, _ *Request) {
+		w.WriteHeader(StatusNoContent)
+	}
+	timeout := 300 * time.Millisecond
+	ts := httptest.NewServer(TimeoutHandler(handler, timeout, ""))
+	defer ts.Close()
+	// Issue was caused by the timeout handler starting the timer when
+	// was created, not when the request. So wait for more than the timeout
+	// to ensure that's not the case.
+	time.Sleep(2 * timeout)
+	res, err := Get(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != StatusNoContent {
+		t.Errorf("got res.StatusCode %d, want %v", res.StatusCode, StatusNoContent)
+	}
+}
+
+// https://golang.org/issue/15948
+func TestTimeoutHandlerEmptyResponse(t *testing.T) {
+	defer afterTest(t)
+	var handler HandlerFunc = func(w ResponseWriter, _ *Request) {
+		// No response.
+	}
+	timeout := 300 * time.Millisecond
+	ts := httptest.NewServer(TimeoutHandler(handler, timeout, ""))
+	defer ts.Close()
+
+	res, err := Get(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer res.Body.Close()
+	if res.StatusCode != StatusOK {
+		t.Errorf("got res.StatusCode %d, want %v", res.StatusCode, StatusOK)
+	}
+}
+
 // Verifies we don't path.Clean() on the wrong parts in redirects.
 func TestRedirectMunging(t *testing.T) {
 	req, _ := NewRequest("GET", "http://example.com/", nil)
@@ -2027,7 +2189,7 @@ func TestHandlerPanicWithHijack(t *testing.T) {
 func testHandlerPanic(t *testing.T, withHijack, h2 bool, panicValue interface{}) {
 	defer afterTest(t)
 	// Unlike the other tests that set the log output to ioutil.Discard
-	// to quiet the output, this test uses a pipe.  The pipe serves three
+	// to quiet the output, this test uses a pipe. The pipe serves three
 	// purposes:
 	//
 	//   1) The log.Print from the http server (generated by the caught
@@ -2060,7 +2222,7 @@ func testHandlerPanic(t *testing.T, withHijack, h2 bool, panicValue interface{})
 	defer cst.close()
 
 	// Do a blocking read on the log output pipe so its logging
-	// doesn't bleed into the next test.  But wait only 5 seconds
+	// doesn't bleed into the next test. But wait only 5 seconds
 	// for it.
 	done := make(chan bool, 1)
 	go func() {
@@ -2205,10 +2367,10 @@ func testRequestBodyLimit(t *testing.T, h2 bool) {
 	nWritten := new(int64)
 	req, _ := NewRequest("POST", cst.ts.URL, io.LimitReader(countReader{neverEnding('a'), nWritten}, limit*200))
 
-	// Send the POST, but don't care it succeeds or not.  The
+	// Send the POST, but don't care it succeeds or not. The
 	// remote side is going to reply and then close the TCP
 	// connection, and HTTP doesn't really define if that's
-	// allowed or not.  Some HTTP clients will get the response
+	// allowed or not. Some HTTP clients will get the response
 	// and some (like ours, currently) will complain that the
 	// request write failed, without reading the response.
 	//
@@ -2650,7 +2812,7 @@ func TestOptions(t *testing.T) {
 }
 
 // Tests regarding the ordering of Write, WriteHeader, Header, and
-// Flush calls.  In Go 1.0, rw.WriteHeader immediately flushed the
+// Flush calls. In Go 1.0, rw.WriteHeader immediately flushed the
 // (*response).header to the wire. In Go 1.1, the actual wire flush is
 // delayed, so we could maybe tack on a Content-Length and better
 // Content-Type after we see more (or all) of the output. To preserve
@@ -3107,7 +3269,7 @@ func testTransportAndServerSharedBodyRace(t *testing.T, h2 bool) {
 
 	const bodySize = 1 << 20
 
-	// errorf is like t.Errorf, but also writes to println.  When
+	// errorf is like t.Errorf, but also writes to println. When
 	// this test fails, it hangs. This helps debugging and I've
 	// added this enough times "temporarily".  It now gets added
 	// full time.
@@ -3829,6 +3991,8 @@ func TestServerValidatesHostHeader(t *testing.T) {
 		host  string
 		want  int
 	}{
+		{"HTTP/0.9", "", 400},
+
 		{"HTTP/1.1", "", 400},
 		{"HTTP/1.1", "Host: \r\n", 200},
 		{"HTTP/1.1", "Host: 1.2.3.4\r\n", 200},
@@ -3851,10 +4015,22 @@ func TestServerValidatesHostHeader(t *testing.T) {
 		{"HTTP/1.0", "", 200},
 		{"HTTP/1.0", "Host: first\r\nHost: second\r\n", 400},
 		{"HTTP/1.0", "Host: \xff\r\n", 400},
+
+		// Make an exception for HTTP upgrade requests:
+		{"PRI * HTTP/2.0", "", 200},
+
+		// But not other HTTP/2 stuff:
+		{"PRI / HTTP/2.0", "", 400},
+		{"GET / HTTP/2.0", "", 400},
+		{"GET / HTTP/3.0", "", 400},
 	}
 	for _, tt := range tests {
 		conn := &testConn{closec: make(chan bool, 1)}
-		io.WriteString(&conn.readBuf, "GET / "+tt.proto+"\r\n"+tt.host+"\r\n")
+		methodTarget := "GET / "
+		if !strings.HasPrefix(tt.proto, "HTTP/") {
+			methodTarget = ""
+		}
+		io.WriteString(&conn.readBuf, methodTarget+tt.proto+"\r\n"+tt.host+"\r\n")
 
 		ln := &oneConnListener{conn}
 		go Serve(ln, HandlerFunc(func(ResponseWriter, *Request) {}))
@@ -3870,6 +4046,45 @@ func TestServerValidatesHostHeader(t *testing.T) {
 	}
 }
 
+func TestServerHandlersCanHandleH2PRI(t *testing.T) {
+	const upgradeResponse = "upgrade here"
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		conn, br, err := w.(Hijacker).Hijack()
+		defer conn.Close()
+		if r.Method != "PRI" || r.RequestURI != "*" {
+			t.Errorf("Got method/target %q %q; want PRI *", r.Method, r.RequestURI)
+			return
+		}
+		if !r.Close {
+			t.Errorf("Request.Close = true; want false")
+		}
+		const want = "SM\r\n\r\n"
+		buf := make([]byte, len(want))
+		n, err := io.ReadFull(br, buf)
+		if err != nil || string(buf[:n]) != want {
+			t.Errorf("Read = %v, %v (%q), want %q", n, err, buf[:n], want)
+			return
+		}
+		io.WriteString(conn, upgradeResponse)
+	}))
+	defer ts.Close()
+
+	c, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatalf("Dial: %v", err)
+	}
+	defer c.Close()
+	io.WriteString(c, "PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n")
+	slurp, err := ioutil.ReadAll(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(slurp) != upgradeResponse {
+		t.Errorf("Handler response = %q; want %q", slurp, upgradeResponse)
+	}
+}
+
 // Test that we validate the valid bytes in HTTP/1 headers.
 // Issue 11207.
 func TestServerValidatesHeaders(t *testing.T) {
@@ -3910,6 +4125,140 @@ func TestServerValidatesHeaders(t *testing.T) {
 	}
 }
 
+func TestServerRequestContextCancel_ServeHTTPDone_h1(t *testing.T) {
+	testServerRequestContextCancel_ServeHTTPDone(t, h1Mode)
+}
+func TestServerRequestContextCancel_ServeHTTPDone_h2(t *testing.T) {
+	testServerRequestContextCancel_ServeHTTPDone(t, h2Mode)
+}
+func testServerRequestContextCancel_ServeHTTPDone(t *testing.T, h2 bool) {
+	defer afterTest(t)
+	ctxc := make(chan context.Context, 1)
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		ctx := r.Context()
+		select {
+		case <-ctx.Done():
+			t.Error("should not be Done in ServeHTTP")
+		default:
+		}
+		ctxc <- ctx
+	}))
+	defer cst.close()
+	res, err := cst.c.Get(cst.ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Body.Close()
+	ctx := <-ctxc
+	select {
+	case <-ctx.Done():
+	default:
+		t.Error("context should be done after ServeHTTP completes")
+	}
+}
+
+func TestServerRequestContextCancel_ConnClose(t *testing.T) {
+	// Currently the context is not canceled when the connection
+	// is closed because we're not reading from the connection
+	// until after ServeHTTP for the previous handler is done.
+	// Until the server code is modified to always be in a read
+	// (Issue 15224), this test doesn't work yet.
+	t.Skip("TODO(bradfitz): this test doesn't yet work; golang.org/issue/15224")
+	defer afterTest(t)
+	inHandler := make(chan struct{})
+	handlerDone := make(chan struct{})
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		close(inHandler)
+		select {
+		case <-r.Context().Done():
+		case <-time.After(3 * time.Second):
+			t.Errorf("timeout waiting for context to be done")
+		}
+		close(handlerDone)
+	}))
+	defer ts.Close()
+	c, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+	io.WriteString(c, "GET / HTTP/1.1\r\nHost: foo\r\n\r\n")
+	select {
+	case <-inHandler:
+	case <-time.After(3 * time.Second):
+		t.Fatalf("timeout waiting to see ServeHTTP get called")
+	}
+	c.Close() // this should trigger the context being done
+
+	select {
+	case <-handlerDone:
+	case <-time.After(3 * time.Second):
+		t.Fatalf("timeout waiting to see ServeHTTP exit")
+	}
+}
+
+func TestServerContext_ServerContextKey_h1(t *testing.T) {
+	testServerContext_ServerContextKey(t, h1Mode)
+}
+func TestServerContext_ServerContextKey_h2(t *testing.T) {
+	testServerContext_ServerContextKey(t, h2Mode)
+}
+func testServerContext_ServerContextKey(t *testing.T, h2 bool) {
+	defer afterTest(t)
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		ctx := r.Context()
+		got := ctx.Value(ServerContextKey)
+		if _, ok := got.(*Server); !ok {
+			t.Errorf("context value = %T; want *http.Server", got)
+		}
+
+		got = ctx.Value(LocalAddrContextKey)
+		if addr, ok := got.(net.Addr); !ok {
+			t.Errorf("local addr value = %T; want net.Addr", got)
+		} else if fmt.Sprint(addr) != r.Host {
+			t.Errorf("local addr = %v; want %v", addr, r.Host)
+		}
+	}))
+	defer cst.close()
+	res, err := cst.c.Get(cst.ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Body.Close()
+}
+
+// https://golang.org/issue/15960
+func TestHandlerSetTransferEncodingChunked(t *testing.T) {
+	defer afterTest(t)
+	ht := newHandlerTest(HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.Header().Set("Transfer-Encoding", "chunked")
+		w.Write([]byte("hello"))
+	}))
+	resp := ht.rawResponse("GET / HTTP/1.1\nHost: foo")
+	const hdr = "Transfer-Encoding: chunked"
+	if n := strings.Count(resp, hdr); n != 1 {
+		t.Errorf("want 1 occurrence of %q in response, got %v\nresponse: %v", hdr, n, resp)
+	}
+}
+
+// https://golang.org/issue/16063
+func TestHandlerSetTransferEncodingGzip(t *testing.T) {
+	defer afterTest(t)
+	ht := newHandlerTest(HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.Header().Set("Transfer-Encoding", "gzip")
+		gz := gzip.NewWriter(w)
+		gz.Write([]byte("hello"))
+		gz.Close()
+	}))
+	resp := ht.rawResponse("GET / HTTP/1.1\nHost: foo")
+	for _, v := range []string{"gzip", "chunked"} {
+		hdr := "Transfer-Encoding: " + v
+		if n := strings.Count(resp, hdr); n != 1 {
+			t.Errorf("want 1 occurrence of %q in response, got %v\nresponse: %v", hdr, n, resp)
+		}
+	}
+}
+
 func BenchmarkClientServer(b *testing.B) {
 	b.ReportAllocs()
 	b.StopTimer()
@@ -4100,7 +4449,7 @@ func BenchmarkClient(b *testing.B) {
 	// Wait for the server process to respond.
 	url := "http://localhost:" + port + "/"
 	for i := 0; i < 100; i++ {
-		time.Sleep(50 * time.Millisecond)
+		time.Sleep(100 * time.Millisecond)
 		if _, err := getNoBody(url); err == nil {
 			break
 		}
@@ -4121,7 +4470,7 @@ func BenchmarkClient(b *testing.B) {
 		if err != nil {
 			b.Fatalf("ReadAll: %v", err)
 		}
-		if bytes.Compare(body, data) != 0 {
+		if !bytes.Equal(body, data) {
 			b.Fatalf("Got body: %q", body)
 		}
 	}
diff --git a/libgo/go/net/http/server.go b/libgo/go/net/http/server.go
index 5e3b6084ae3..7b2b4b2f423 100644
--- a/libgo/go/net/http/server.go
+++ b/libgo/go/net/http/server.go
@@ -2,13 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// HTTP server.  See RFC 2616.
+// HTTP server. See RFC 2616.
 
 package http
 
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"crypto/tls"
 	"errors"
 	"fmt"
@@ -26,14 +27,30 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
+
+	"golang_org/x/net/lex/httplex"
 )
 
-// Errors introduced by the HTTP server.
+// Errors used by the HTTP server.
 var (
-	ErrWriteAfterFlush = errors.New("Conn.Write called after Flush")
-	ErrBodyNotAllowed  = errors.New("http: request method or response status code does not allow body")
-	ErrHijacked        = errors.New("Conn has been hijacked")
-	ErrContentLength   = errors.New("Conn.Write wrote more than the declared Content-Length")
+	// ErrBodyNotAllowed is returned by ResponseWriter.Write calls
+	// when the HTTP method or response code does not permit a
+	// body.
+	ErrBodyNotAllowed = errors.New("http: request method or response status code does not allow body")
+
+	// ErrHijacked is returned by ResponseWriter.Write calls when
+	// the underlying connection has been hijacked using the
+	// Hijacker interfaced.
+	ErrHijacked = errors.New("http: connection has been hijacked")
+
+	// ErrContentLength is returned by ResponseWriter.Write calls
+	// when a Handler set a Content-Length response header with a
+	// declared size and then attempted to write more bytes than
+	// declared.
+	ErrContentLength = errors.New("http: wrote more than the declared Content-Length")
+
+	// Deprecated: ErrWriteAfterFlush is no longer used.
+	ErrWriteAfterFlush = errors.New("unused")
 )
 
 // A Handler responds to an HTTP request.
@@ -50,6 +67,9 @@ var (
 // ResponseWriter. Cautious handlers should read the Request.Body
 // first, and then reply.
 //
+// Except for reading the body, handlers should not modify the
+// provided Request.
+//
 // If ServeHTTP panics, the server (the caller of ServeHTTP) assumes
 // that the effect of the panic was isolated to the active request.
 // It recovers the panic, logs a stack trace to the server error log,
@@ -73,10 +93,24 @@ type ResponseWriter interface {
 	Header() Header
 
 	// Write writes the data to the connection as part of an HTTP reply.
-	// If WriteHeader has not yet been called, Write calls WriteHeader(http.StatusOK)
-	// before writing the data.  If the Header does not contain a
-	// Content-Type line, Write adds a Content-Type set to the result of passing
-	// the initial 512 bytes of written data to DetectContentType.
+	//
+	// If WriteHeader has not yet been called, Write calls
+	// WriteHeader(http.StatusOK) before writing the data. If the Header
+	// does not contain a Content-Type line, Write adds a Content-Type set
+	// to the result of passing the initial 512 bytes of written data to
+	// DetectContentType.
+	//
+	// Depending on the HTTP protocol version and the client, calling
+	// Write or WriteHeader may prevent future reads on the
+	// Request.Body. For HTTP/1.x requests, handlers should read any
+	// needed request body data before writing the response. Once the
+	// headers have been flushed (due to either an explicit Flusher.Flush
+	// call or writing enough data to trigger a flush), the request body
+	// may be unavailable. For HTTP/2 requests, the Go HTTP server permits
+	// handlers to continue to read the request body while concurrently
+	// writing the response. However, such behavior may not be supported
+	// by all HTTP/2 clients. Handlers should read before writing if
+	// possible to maximize compatibility.
 	Write([]byte) (int, error)
 
 	// WriteHeader sends an HTTP response header with status code.
@@ -90,6 +124,10 @@ type ResponseWriter interface {
 // The Flusher interface is implemented by ResponseWriters that allow
 // an HTTP handler to flush buffered data to the client.
 //
+// The default HTTP/1.x and HTTP/2 ResponseWriter implementations
+// support Flusher, but ResponseWriter wrappers may not. Handlers
+// should always test for this ability at runtime.
+//
 // Note that even for ResponseWriters that support Flush,
 // if the client is connected through an HTTP proxy,
 // the buffered data may not reach the client until the response
@@ -101,6 +139,11 @@ type Flusher interface {
 
 // The Hijacker interface is implemented by ResponseWriters that allow
 // an HTTP handler to take over the connection.
+//
+// The default ResponseWriter for HTTP/1.x connections supports
+// Hijacker, but HTTP/2 connections intentionally do not.
+// ResponseWriter wrappers may also not support Hijacker. Handlers
+// should always test for this ability at runtime.
 type Hijacker interface {
 	// Hijack lets the caller take over the connection.
 	// After a call to Hijack(), the HTTP server library
@@ -143,6 +186,20 @@ type CloseNotifier interface {
 	CloseNotify() <-chan bool
 }
 
+var (
+	// ServerContextKey is a context key. It can be used in HTTP
+	// handlers with context.WithValue to access the server that
+	// started the handler. The associated value will be of
+	// type *Server.
+	ServerContextKey = &contextKey{"http-server"}
+
+	// LocalAddrContextKey is a context key. It can be used in
+	// HTTP handlers with context.WithValue to access the address
+	// the local address the connection arrived on.
+	// The associated value will be of type net.Addr.
+	LocalAddrContextKey = &contextKey{"local-addr"}
+)
+
 // A conn represents the server side of an HTTP connection.
 type conn struct {
 	// server is the server on which the connection arrived.
@@ -306,11 +363,14 @@ func (cw *chunkWriter) close() {
 
 // A response represents the server side of an HTTP response.
 type response struct {
-	conn          *conn
-	req           *Request // request for this response
-	reqBody       io.ReadCloser
-	wroteHeader   bool // reply header has been (logically) written
-	wroteContinue bool // 100 Continue response was written
+	conn             *conn
+	req              *Request // request for this response
+	reqBody          io.ReadCloser
+	cancelCtx        context.CancelFunc // when ServeHTTP exits
+	wroteHeader      bool               // reply header has been (logically) written
+	wroteContinue    bool               // 100 Continue response was written
+	wants10KeepAlive bool               // HTTP/1.0 w/ Connection "keep-alive"
+	wantsClose       bool               // HTTP request has Connection "close"
 
 	w  *bufio.Writer // buffers output in chunks to chunkWriter
 	cw chunkWriter
@@ -342,7 +402,7 @@ type response struct {
 	requestBodyLimitHit bool
 
 	// trailers are the headers to be sent after the handler
-	// finishes writing the body.  This field is initialized from
+	// finishes writing the body. This field is initialized from
 	// the Trailer response header when the response header is
 	// written.
 	trailers []string
@@ -497,7 +557,7 @@ type connReader struct {
 }
 
 func (cr *connReader) setReadLimit(remain int64) { cr.remain = remain }
-func (cr *connReader) setInfiniteReadLimit()     { cr.remain = 1<<63 - 1 }
+func (cr *connReader) setInfiniteReadLimit()     { cr.remain = maxInt64 }
 func (cr *connReader) hitReadLimit() bool        { return cr.remain <= 0 }
 
 func (cr *connReader) Read(p []byte) (n int, err error) {
@@ -681,7 +741,7 @@ func appendTime(b []byte, t time.Time) []byte {
 var errTooLarge = errors.New("http: request too large")
 
 // Read next request from connection.
-func (c *conn) readRequest() (w *response, err error) {
+func (c *conn) readRequest(ctx context.Context) (w *response, err error) {
 	if c.hijacked() {
 		return nil, ErrHijacked
 	}
@@ -710,31 +770,39 @@ func (c *conn) readRequest() (w *response, err error) {
 		}
 		return nil, err
 	}
+
+	if !http1ServerSupportsRequest(req) {
+		return nil, badRequestError("unsupported protocol version")
+	}
+
 	c.lastMethod = req.Method
 	c.r.setInfiniteReadLimit()
 
 	hosts, haveHost := req.Header["Host"]
-	if req.ProtoAtLeast(1, 1) && (!haveHost || len(hosts) == 0) {
+	isH2Upgrade := req.isH2Upgrade()
+	if req.ProtoAtLeast(1, 1) && (!haveHost || len(hosts) == 0) && !isH2Upgrade {
 		return nil, badRequestError("missing required Host header")
 	}
 	if len(hosts) > 1 {
 		return nil, badRequestError("too many Host headers")
 	}
-	if len(hosts) == 1 && !validHostHeader(hosts[0]) {
+	if len(hosts) == 1 && !httplex.ValidHostHeader(hosts[0]) {
 		return nil, badRequestError("malformed Host header")
 	}
 	for k, vv := range req.Header {
-		if !validHeaderName(k) {
+		if !httplex.ValidHeaderFieldName(k) {
 			return nil, badRequestError("invalid header name")
 		}
 		for _, v := range vv {
-			if !validHeaderValue(v) {
+			if !httplex.ValidHeaderFieldValue(v) {
 				return nil, badRequestError("invalid header value")
 			}
 		}
 	}
 	delete(req.Header, "Host")
 
+	ctx, cancelCtx := context.WithCancel(ctx)
+	req.ctx = ctx
 	req.RemoteAddr = c.remoteAddr
 	req.TLS = c.tlsState
 	if body, ok := req.Body.(*body); ok {
@@ -743,16 +811,43 @@ func (c *conn) readRequest() (w *response, err error) {
 
 	w = &response{
 		conn:          c,
+		cancelCtx:     cancelCtx,
 		req:           req,
 		reqBody:       req.Body,
 		handlerHeader: make(Header),
 		contentLength: -1,
+
+		// We populate these ahead of time so we're not
+		// reading from req.Header after their Handler starts
+		// and maybe mutates it (Issue 14940)
+		wants10KeepAlive: req.wantsHttp10KeepAlive(),
+		wantsClose:       req.wantsClose(),
+	}
+	if isH2Upgrade {
+		w.closeAfterReply = true
 	}
 	w.cw.res = w
 	w.w = newBufioWriterSize(&w.cw, bufferBeforeChunkingSize)
 	return w, nil
 }
 
+// http1ServerSupportsRequest reports whether Go's HTTP/1.x server
+// supports the given request.
+func http1ServerSupportsRequest(req *Request) bool {
+	if req.ProtoMajor == 1 {
+		return true
+	}
+	// Accept "PRI * HTTP/2.0" upgrade requests, so Handlers can
+	// wire up their own HTTP/2 upgrades.
+	if req.ProtoMajor == 2 && req.ProtoMinor == 0 &&
+		req.Method == "PRI" && req.RequestURI == "*" {
+		return true
+	}
+	// Reject HTTP/0.x, and all other HTTP/2+ requests (which
+	// aren't encoded in ASCII anyway).
+	return false
+}
+
 func (w *response) Header() Header {
 	if w.cw.header == nil && w.wroteHeader && !w.cw.wroteHeader {
 		// Accessing the header between logically writing it
@@ -766,7 +861,7 @@ func (w *response) Header() Header {
 
 // maxPostHandlerReadBytes is the max number of Request.Body bytes not
 // consumed by a handler that the server will read from the client
-// in order to keep a connection alive.  If there are more bytes than
+// in order to keep a connection alive. If there are more bytes than
 // this then the server to be paranoid instead sends a "Connection:
 // close" response.
 //
@@ -855,8 +950,8 @@ func (h extraHeader) Write(w *bufio.Writer) {
 // to cw.res.conn.bufw.
 //
 // p is not written by writeHeader, but is the first chunk of the body
-// that will be written.  It is sniffed for a Content-Type if none is
-// set explicitly.  It's also used to set the Content-Length, if the
+// that will be written. It is sniffed for a Content-Type if none is
+// set explicitly. It's also used to set the Content-Length, if the
 // total body size was small and the handler has already finished
 // running.
 func (cw *chunkWriter) writeHeader(p []byte) {
@@ -911,9 +1006,9 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 	// Exceptions: 304/204/1xx responses never get Content-Length, and if
 	// it was a HEAD request, we don't know the difference between
 	// 0 actual bytes and 0 bytes because the handler noticed it
-	// was a HEAD request and chose not to write anything.  So for
+	// was a HEAD request and chose not to write anything. So for
 	// HEAD, the handler should either write the Content-Length or
-	// write non-zero bytes.  If it's actually 0 bytes and the
+	// write non-zero bytes. If it's actually 0 bytes and the
 	// handler never looked at the Request.Method, we just don't
 	// send a Content-Length header.
 	// Further, we don't send an automatic Content-Length if they
@@ -925,7 +1020,7 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 
 	// If this was an HTTP/1.0 request with keep-alive and we sent a
 	// Content-Length back, we can make this a keep-alive response ...
-	if w.req.wantsHttp10KeepAlive() && keepAlivesEnabled {
+	if w.wants10KeepAlive && keepAlivesEnabled {
 		sentLength := header.get("Content-Length") != ""
 		if sentLength && header.get("Connection") == "keep-alive" {
 			w.closeAfterReply = false
@@ -935,12 +1030,12 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 	// Check for a explicit (and valid) Content-Length header.
 	hasCL := w.contentLength != -1
 
-	if w.req.wantsHttp10KeepAlive() && (isHEAD || hasCL) {
+	if w.wants10KeepAlive && (isHEAD || hasCL || !bodyAllowedForStatus(w.status)) {
 		_, connectionHeaderSet := header["Connection"]
 		if !connectionHeaderSet {
 			setHeader.connection = "keep-alive"
 		}
-	} else if !w.req.ProtoAtLeast(1, 1) || w.req.wantsClose() {
+	} else if !w.req.ProtoAtLeast(1, 1) || w.wantsClose {
 		w.closeAfterReply = true
 	}
 
@@ -965,9 +1060,12 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 	}
 
 	// Per RFC 2616, we should consume the request body before
-	// replying, if the handler hasn't already done so.  But we
+	// replying, if the handler hasn't already done so. But we
 	// don't want to do an unbounded amount of reading here for
 	// DoS reasons, so we only try up to a threshold.
+	// TODO(bradfitz): where does RFC 2616 say that? See Issue 15527
+	// about HTTP/1.x Handlers concurrently reading and writing, like
+	// HTTP/2 handlers can do. Maybe this code should be relaxed?
 	if w.req.ContentLength != 0 && !w.closeAfterReply {
 		var discard, tooBig bool
 
@@ -1009,7 +1107,7 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 					w.closeAfterReply = true
 				}
 			default:
-				// Some other kind of error occured, like a read timeout, or
+				// Some other kind of error occurred, like a read timeout, or
 				// corrupt chunked encoding. In any case, whatever remains
 				// on the wire must not be parsed as another HTTP request.
 				w.closeAfterReply = true
@@ -1069,6 +1167,10 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 			// to avoid closing the connection at EOF.
 			cw.chunking = true
 			setHeader.transferEncoding = "chunked"
+			if hasTE && te == "chunked" {
+				// We will send the chunked Transfer-Encoding header later.
+				delHeader("Transfer-Encoding")
+			}
 		}
 	} else {
 		// HTTP version < 1.1: cannot do chunked transfer
@@ -1148,7 +1250,7 @@ func statusLine(req *Request, code int) string {
 	if proto11 {
 		proto = "HTTP/1.1"
 	}
-	codestring := strconv.Itoa(code)
+	codestring := fmt.Sprintf("%03d", code)
 	text, ok := statusText[code]
 	if !ok {
 		text = "status code " + codestring
@@ -1174,7 +1276,7 @@ func (w *response) bodyAllowed() bool {
 // The Life Of A Write is like this:
 //
 // Handler starts. No header has been sent. The handler can either
-// write a header, or just start writing.  Writing before sending a header
+// write a header, or just start writing. Writing before sending a header
 // sends an implicitly empty 200 OK header.
 //
 // If the handler didn't declare a Content-Length up front, we either
@@ -1200,7 +1302,7 @@ func (w *response) bodyAllowed() bool {
 // initial header contains both a Content-Type and Content-Length.
 // Also short-circuit in (1) when the header's been sent and not in
 // chunking mode, writing directly to (4) instead, if (2) has no
-// buffered data.  More generally, we could short-circuit from (1) to
+// buffered data. More generally, we could short-circuit from (1) to
 // (3) even in chunking mode if the write size from (1) is over some
 // threshold and nothing is in (2).  The answer might be mostly making
 // bufferBeforeChunkingSize smaller and having bufio's fast-paths deal
@@ -1341,7 +1443,7 @@ type closeWriter interface {
 var _ closeWriter = (*net.TCPConn)(nil)
 
 // closeWrite flushes any outstanding data and sends a FIN packet (if
-// client is connected via TCP), signalling that we're done.  We then
+// client is connected via TCP), signalling that we're done. We then
 // pause for a bit, hoping the client processes it before any
 // subsequent RST.
 //
@@ -1355,7 +1457,7 @@ func (c *conn) closeWriteAndWait() {
 }
 
 // validNPN reports whether the proto is not a blacklisted Next
-// Protocol Negotiation protocol.  Empty and built-in protocol types
+// Protocol Negotiation protocol. Empty and built-in protocol types
 // are blacklisted and can't be overridden with alternate
 // implementations.
 func validNPN(proto string) bool {
@@ -1374,13 +1476,13 @@ func (c *conn) setState(nc net.Conn, state ConnState) {
 
 // badRequestError is a literal string (used by in the server in HTML,
 // unescaped) to tell the user why their request was bad. It should
-// be plain text without user info or other embeddded errors.
+// be plain text without user info or other embedded errors.
 type badRequestError string
 
 func (e badRequestError) Error() string { return "Bad Request: " + string(e) }
 
 // Serve a new connection.
-func (c *conn) serve() {
+func (c *conn) serve(ctx context.Context) {
 	c.remoteAddr = c.rwc.RemoteAddr().String()
 	defer func() {
 		if err := recover(); err != nil {
@@ -1417,12 +1519,17 @@ func (c *conn) serve() {
 		}
 	}
 
+	// HTTP/1.x from here on.
+
 	c.r = &connReader{r: c.rwc}
 	c.bufr = newBufioReader(c.r)
 	c.bufw = newBufioWriterSize(checkConnErrorWriter{c}, 4<<10)
 
+	ctx, cancelCtx := context.WithCancel(ctx)
+	defer cancelCtx()
+
 	for {
-		w, err := c.readRequest()
+		w, err := c.readRequest(ctx)
 		if c.r.remain != c.server.initialReadLimitSize() {
 			// If we read any bytes off the wire, we're active.
 			c.setState(c.rwc, StateActive)
@@ -1433,7 +1540,7 @@ func (c *conn) serve() {
 				// able to read this if we're
 				// responding to them and hanging up
 				// while they're still writing their
-				// request.  Undefined behavior.
+				// request. Undefined behavior.
 				io.WriteString(c.rwc, "HTTP/1.1 431 Request Header Fields Too Large\r\nContent-Type: text/plain\r\nConnection: close\r\n\r\n431 Request Header Fields Too Large")
 				c.closeWriteAndWait()
 				return
@@ -1467,9 +1574,10 @@ func (c *conn) serve() {
 		// HTTP cannot have multiple simultaneous active requests.[*]
 		// Until the server replies to this request, it can't read another,
 		// so we might as well run the handler in this goroutine.
-		// [*] Not strictly true: HTTP pipelining.  We could let them all process
+		// [*] Not strictly true: HTTP pipelining. We could let them all process
 		// in parallel even if their responses need to be serialized.
 		serverHandler{c.server}.ServeHTTP(w, w.req)
+		w.cancelCtx()
 		if c.hijacked() {
 			return
 		}
@@ -1488,7 +1596,7 @@ func (w *response) sendExpectationFailed() {
 	// TODO(bradfitz): let ServeHTTP handlers handle
 	// requests with non-standard expectation[s]? Seems
 	// theoretical at best, and doesn't fit into the
-	// current ServeHTTP model anyway.  We'd need to
+	// current ServeHTTP model anyway. We'd need to
 	// make the ResponseWriter an optional
 	// "ExpectReplier" interface or something.
 	//
@@ -1608,7 +1716,7 @@ func requestBodyRemains(rc io.ReadCloser) bool {
 }
 
 // The HandlerFunc type is an adapter to allow the use of
-// ordinary functions as HTTP handlers.  If f is a function
+// ordinary functions as HTTP handlers. If f is a function
 // with the appropriate signature, HandlerFunc(f) is a
 // Handler that calls f.
 type HandlerFunc func(ResponseWriter, *Request)
@@ -1621,6 +1729,8 @@ func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {
 // Helper handlers
 
 // Error replies to the request with the specified error message and HTTP code.
+// It does not otherwise end the request; the caller should ensure no further
+// writes are done to w.
 // The error message should be plain text.
 func Error(w ResponseWriter, error string, code int) {
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
@@ -1709,7 +1819,7 @@ func Redirect(w ResponseWriter, r *Request, urlStr string, code int) {
 	w.Header().Set("Location", urlStr)
 	w.WriteHeader(code)
 
-	// RFC2616 recommends that a short note "SHOULD" be included in the
+	// RFC 2616 recommends that a short note "SHOULD" be included in the
 	// response because older user agents may not understand 301/307.
 	// Shouldn't send the response for POST or HEAD; that leaves GET.
 	if r.Method == "GET" {
@@ -1779,7 +1889,7 @@ func RedirectHandler(url string, code int) Handler {
 // been registered separately.
 //
 // Patterns may optionally begin with a host name, restricting matches to
-// URLs on that host only.  Host-specific patterns take precedence over
+// URLs on that host only. Host-specific patterns take precedence over
 // general patterns, so that a handler might register for the two patterns
 // "/codesearch" and "codesearch.google.com/" without also taking over
 // requests for "http://www.google.com/".
@@ -1800,10 +1910,12 @@ type muxEntry struct {
 }
 
 // NewServeMux allocates and returns a new ServeMux.
-func NewServeMux() *ServeMux { return &ServeMux{m: make(map[string]muxEntry)} }
+func NewServeMux() *ServeMux { return new(ServeMux) }
 
 // DefaultServeMux is the default ServeMux used by Serve.
-var DefaultServeMux = NewServeMux()
+var DefaultServeMux = &defaultServeMux
+
+var defaultServeMux ServeMux
 
 // Does path match pattern?
 func pathMatch(pattern, path string) bool {
@@ -1926,6 +2038,9 @@ func (mux *ServeMux) Handle(pattern string, handler Handler) {
 		panic("http: multiple registrations for " + pattern)
 	}
 
+	if mux.m == nil {
+		mux.m = make(map[string]muxEntry)
+	}
 	mux.m[pattern] = muxEntry{explicit: true, h: handler, pattern: pattern}
 
 	if pattern[0] != '/' {
@@ -1968,7 +2083,7 @@ func HandleFunc(pattern string, handler func(ResponseWriter, *Request)) {
 }
 
 // Serve accepts incoming HTTP connections on the listener l,
-// creating a new service goroutine for each.  The service goroutines
+// creating a new service goroutine for each. The service goroutines
 // read requests and then call handler to reply to them.
 // Handler is typically nil, in which case the DefaultServeMux is used.
 func Serve(l net.Listener, handler Handler) error {
@@ -1979,19 +2094,25 @@ func Serve(l net.Listener, handler Handler) error {
 // A Server defines parameters for running an HTTP server.
 // The zero value for Server is a valid configuration.
 type Server struct {
-	Addr           string        // TCP address to listen on, ":http" if empty
-	Handler        Handler       // handler to invoke, http.DefaultServeMux if nil
-	ReadTimeout    time.Duration // maximum duration before timing out read of the request
-	WriteTimeout   time.Duration // maximum duration before timing out write of the response
-	MaxHeaderBytes int           // maximum size of request headers, DefaultMaxHeaderBytes if 0
-	TLSConfig      *tls.Config   // optional TLS config, used by ListenAndServeTLS
+	Addr         string        // TCP address to listen on, ":http" if empty
+	Handler      Handler       // handler to invoke, http.DefaultServeMux if nil
+	ReadTimeout  time.Duration // maximum duration before timing out read of the request
+	WriteTimeout time.Duration // maximum duration before timing out write of the response
+	TLSConfig    *tls.Config   // optional TLS config, used by ListenAndServeTLS
+
+	// MaxHeaderBytes controls the maximum number of bytes the
+	// server will read parsing the request header's keys and
+	// values, including the request line. It does not limit the
+	// size of the request body.
+	// If zero, DefaultMaxHeaderBytes is used.
+	MaxHeaderBytes int
 
 	// TLSNextProto optionally specifies a function to take over
-	// ownership of the provided TLS connection when an NPN
-	// protocol upgrade has occurred.  The map key is the protocol
+	// ownership of the provided TLS connection when an NPN/ALPN
+	// protocol upgrade has occurred. The map key is the protocol
 	// name negotiated. The Handler argument should be used to
 	// handle HTTP requests and will initialize the Request's TLS
-	// and RemoteAddr if not already set.  The connection is
+	// and RemoteAddr if not already set. The connection is
 	// automatically closed when the function returns.
 	// If TLSNextProto is nil, HTTP/2 support is enabled automatically.
 	TLSNextProto map[string]func(*Server, *tls.Conn, Handler)
@@ -2032,7 +2153,7 @@ const (
 	// For HTTP/2, StateActive fires on the transition from zero
 	// to one active request, and only transitions away once all
 	// active requests are complete. That means that ConnState
-	// can not be used to do per-request work; ConnState only notes
+	// cannot be used to do per-request work; ConnState only notes
 	// the overall state of the connection.
 	StateActive
 
@@ -2100,9 +2221,37 @@ func (srv *Server) ListenAndServe() error {
 
 var testHookServerServe func(*Server, net.Listener) // used if non-nil
 
+// shouldDoServeHTTP2 reports whether Server.Serve should configure
+// automatic HTTP/2. (which sets up the srv.TLSNextProto map)
+func (srv *Server) shouldConfigureHTTP2ForServe() bool {
+	if srv.TLSConfig == nil {
+		// Compatibility with Go 1.6:
+		// If there's no TLSConfig, it's possible that the user just
+		// didn't set it on the http.Server, but did pass it to
+		// tls.NewListener and passed that listener to Serve.
+		// So we should configure HTTP/2 (to set up srv.TLSNextProto)
+		// in case the listener returns an "h2" *tls.Conn.
+		return true
+	}
+	// The user specified a TLSConfig on their http.Server.
+	// In this, case, only configure HTTP/2 if their tls.Config
+	// explicitly mentions "h2". Otherwise http2.ConfigureServer
+	// would modify the tls.Config to add it, but they probably already
+	// passed this tls.Config to tls.NewListener. And if they did,
+	// it's too late anyway to fix it. It would only be potentially racy.
+	// See Issue 15908.
+	return strSliceContains(srv.TLSConfig.NextProtos, http2NextProtoTLS)
+}
+
 // Serve accepts incoming connections on the Listener l, creating a
 // new service goroutine for each. The service goroutines read requests and
 // then call srv.Handler to reply to them.
+//
+// For HTTP/2 support, srv.TLSConfig should be initialized to the
+// provided listener's TLS Config before calling Serve. If
+// srv.TLSConfig is non-nil and doesn't include the string "h2" in
+// Config.NextProtos, HTTP/2 support is not enabled.
+//
 // Serve always returns a non-nil error.
 func (srv *Server) Serve(l net.Listener) error {
 	defer l.Close()
@@ -2110,9 +2259,18 @@ func (srv *Server) Serve(l net.Listener) error {
 		fn(srv, l)
 	}
 	var tempDelay time.Duration // how long to sleep on accept failure
-	if err := srv.setupHTTP2(); err != nil {
-		return err
+
+	if srv.shouldConfigureHTTP2ForServe() {
+		if err := srv.setupHTTP2(); err != nil {
+			return err
+		}
 	}
+
+	// TODO: allow changing base context? can't imagine concrete
+	// use cases yet.
+	baseCtx := context.Background()
+	ctx := context.WithValue(baseCtx, ServerContextKey, srv)
+	ctx = context.WithValue(ctx, LocalAddrContextKey, l.Addr())
 	for {
 		rw, e := l.Accept()
 		if e != nil {
@@ -2134,7 +2292,7 @@ func (srv *Server) Serve(l net.Listener) error {
 		tempDelay = 0
 		c := srv.newConn(rw)
 		c.setState(c.rwc, StateNew) // before Serve can return
-		go c.serve()
+		go c.serve(ctx)
 	}
 }
 
@@ -2309,15 +2467,10 @@ func (srv *Server) onceSetNextProtoDefaults() {
 // TimeoutHandler buffers all Handler writes to memory and does not
 // support the Hijacker or Flusher interfaces.
 func TimeoutHandler(h Handler, dt time.Duration, msg string) Handler {
-	t := time.NewTimer(dt)
 	return &timeoutHandler{
 		handler: h,
 		body:    msg,
-
-		// Effectively storing a *time.Timer, but decomposed
-		// for testing:
-		timeout:     func() <-chan time.Time { return t.C },
-		cancelTimer: t.Stop,
+		dt:      dt,
 	}
 }
 
@@ -2328,12 +2481,11 @@ var ErrHandlerTimeout = errors.New("http: Handler timeout")
 type timeoutHandler struct {
 	handler Handler
 	body    string
+	dt      time.Duration
 
-	// timeout returns the channel of a *time.Timer and
-	// cancelTimer cancels it.  They're stored separately for
-	// testing purposes.
-	timeout     func() <-chan time.Time // returns channel producing a timeout
-	cancelTimer func() bool             // optional
+	// When set, no timer will be created and this channel will
+	// be used instead.
+	testTimeout <-chan time.Time
 }
 
 func (h *timeoutHandler) errorBody() string {
@@ -2344,6 +2496,12 @@ func (h *timeoutHandler) errorBody() string {
 }
 
 func (h *timeoutHandler) ServeHTTP(w ResponseWriter, r *Request) {
+	var t *time.Timer
+	timeout := h.testTimeout
+	if timeout == nil {
+		t = time.NewTimer(h.dt)
+		timeout = t.C
+	}
 	done := make(chan struct{})
 	tw := &timeoutWriter{
 		w: w,
@@ -2361,12 +2519,15 @@ func (h *timeoutHandler) ServeHTTP(w ResponseWriter, r *Request) {
 		for k, vv := range tw.h {
 			dst[k] = vv
 		}
+		if !tw.wroteHeader {
+			tw.code = StatusOK
+		}
 		w.WriteHeader(tw.code)
 		w.Write(tw.wbuf.Bytes())
-		if h.cancelTimer != nil {
-			h.cancelTimer()
+		if t != nil {
+			t.Stop()
 		}
-	case <-h.timeout():
+	case <-timeout:
 		tw.mu.Lock()
 		defer tw.mu.Unlock()
 		w.WriteHeader(StatusServiceUnavailable)
diff --git a/libgo/go/net/http/sniff.go b/libgo/go/net/http/sniff.go
index 18810bad068..0d21b44a560 100644
--- a/libgo/go/net/http/sniff.go
+++ b/libgo/go/net/http/sniff.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -14,8 +14,8 @@ const sniffLen = 512
 
 // DetectContentType implements the algorithm described
 // at http://mimesniff.spec.whatwg.org/ to determine the
-// Content-Type of the given data.  It considers at most the
-// first 512 bytes of data.  DetectContentType always returns
+// Content-Type of the given data. It considers at most the
+// first 512 bytes of data. DetectContentType always returns
 // a valid MIME type: if it cannot determine a more specific one, it
 // returns "application/octet-stream".
 func DetectContentType(data []byte) string {
@@ -91,12 +91,41 @@ var sniffSignatures = []sniffSig{
 		ct:   "image/webp",
 	},
 	&exactSig{[]byte("\x00\x00\x01\x00"), "image/vnd.microsoft.icon"},
-	&exactSig{[]byte("\x4F\x67\x67\x53\x00"), "application/ogg"},
 	&maskedSig{
 		mask: []byte("\xFF\xFF\xFF\xFF\x00\x00\x00\x00\xFF\xFF\xFF\xFF"),
 		pat:  []byte("RIFF\x00\x00\x00\x00WAVE"),
 		ct:   "audio/wave",
 	},
+	&maskedSig{
+		mask: []byte("\xFF\xFF\xFF\xFF\x00\x00\x00\x00\xFF\xFF\xFF\xFF"),
+		pat:  []byte("FORM\x00\x00\x00\x00AIFF"),
+		ct:   "audio/aiff",
+	},
+	&maskedSig{
+		mask: []byte("\xFF\xFF\xFF\xFF"),
+		pat:  []byte(".snd"),
+		ct:   "audio/basic",
+	},
+	&maskedSig{
+		mask: []byte("OggS\x00"),
+		pat:  []byte("\x4F\x67\x67\x53\x00"),
+		ct:   "application/ogg",
+	},
+	&maskedSig{
+		mask: []byte("\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF"),
+		pat:  []byte("MThd\x00\x00\x00\x06"),
+		ct:   "audio/midi",
+	},
+	&maskedSig{
+		mask: []byte("\xFF\xFF\xFF"),
+		pat:  []byte("ID3"),
+		ct:   "audio/mpeg",
+	},
+	&maskedSig{
+		mask: []byte("\xFF\xFF\xFF\xFF\x00\x00\x00\x00\xFF\xFF\xFF\xFF"),
+		pat:  []byte("RIFF\x00\x00\x00\x00AVI "),
+		ct:   "video/avi",
+	},
 	&exactSig{[]byte("\x1A\x45\xDF\xA3"), "video/webm"},
 	&exactSig{[]byte("\x52\x61\x72\x20\x1A\x07\x00"), "application/x-rar-compressed"},
 	&exactSig{[]byte("\x50\x4B\x03\x04"), "application/zip"},
@@ -126,9 +155,15 @@ type maskedSig struct {
 }
 
 func (m *maskedSig) match(data []byte, firstNonWS int) string {
+	// pattern matching algorithm section 6
+	// https://mimesniff.spec.whatwg.org/#pattern-matching-algorithm
+
 	if m.skipWS {
 		data = data[firstNonWS:]
 	}
+	if len(m.pat) != len(m.mask) {
+		return ""
+	}
 	if len(data) < len(m.mask) {
 		return ""
 	}
diff --git a/libgo/go/net/http/sniff_test.go b/libgo/go/net/http/sniff_test.go
index e0085516da3..ac404bfa723 100644
--- a/libgo/go/net/http/sniff_test.go
+++ b/libgo/go/net/http/sniff_test.go
@@ -39,7 +39,18 @@ var sniffTests = []struct {
 	{"GIF 87a", []byte(`GIF87a`), "image/gif"},
 	{"GIF 89a", []byte(`GIF89a...`), "image/gif"},
 
+	// Audio types.
+	{"MIDI audio", []byte("MThd\x00\x00\x00\x06\x00\x01"), "audio/midi"},
+	{"MP3 audio/MPEG audio", []byte("ID3\x03\x00\x00\x00\x00\x0f"), "audio/mpeg"},
+	{"WAV audio #1", []byte("RIFFb\xb8\x00\x00WAVEfmt \x12\x00\x00\x00\x06"), "audio/wave"},
+	{"WAV audio #2", []byte("RIFF,\x00\x00\x00WAVEfmt \x12\x00\x00\x00\x06"), "audio/wave"},
+	{"AIFF audio #1", []byte("FORM\x00\x00\x00\x00AIFFCOMM\x00\x00\x00\x12\x00\x01\x00\x00\x57\x55\x00\x10\x40\x0d\xf3\x34"), "audio/aiff"},
+	{"OGG audio", []byte("OggS\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x7e\x46\x00\x00\x00\x00\x00\x00\x1f\xf6\xb4\xfc\x01\x1e\x01\x76\x6f\x72"), "application/ogg"},
+
+	// Video types.
 	{"MP4 video", []byte("\x00\x00\x00\x18ftypmp42\x00\x00\x00\x00mp42isom<\x06t\xbfmdat"), "video/mp4"},
+	{"AVI video #1", []byte("RIFF,O\n\x00AVI LISTÀ"), "video/avi"},
+	{"AVI video #2", []byte("RIFF,\n\x00\x00AVI LISTÀ"), "video/avi"},
 }
 
 func TestDetectContentType(t *testing.T) {
diff --git a/libgo/go/net/http/status.go b/libgo/go/net/http/status.go
index f3dacab6a92..98645b7d746 100644
--- a/libgo/go/net/http/status.go
+++ b/libgo/go/net/http/status.go
@@ -4,63 +4,79 @@
 
 package http
 
-// HTTP status codes, defined in RFC 2616.
+// HTTP status codes as registered with IANA.
+// See: http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
 const (
-	StatusContinue           = 100
-	StatusSwitchingProtocols = 101
+	StatusContinue           = 100 // RFC 7231, 6.2.1
+	StatusSwitchingProtocols = 101 // RFC 7231, 6.2.2
+	StatusProcessing         = 102 // RFC 2518, 10.1
 
-	StatusOK                   = 200
-	StatusCreated              = 201
-	StatusAccepted             = 202
-	StatusNonAuthoritativeInfo = 203
-	StatusNoContent            = 204
-	StatusResetContent         = 205
-	StatusPartialContent       = 206
+	StatusOK                   = 200 // RFC 7231, 6.3.1
+	StatusCreated              = 201 // RFC 7231, 6.3.2
+	StatusAccepted             = 202 // RFC 7231, 6.3.3
+	StatusNonAuthoritativeInfo = 203 // RFC 7231, 6.3.4
+	StatusNoContent            = 204 // RFC 7231, 6.3.5
+	StatusResetContent         = 205 // RFC 7231, 6.3.6
+	StatusPartialContent       = 206 // RFC 7233, 4.1
+	StatusMultiStatus          = 207 // RFC 4918, 11.1
+	StatusAlreadyReported      = 208 // RFC 5842, 7.1
+	StatusIMUsed               = 226 // RFC 3229, 10.4.1
 
-	StatusMultipleChoices   = 300
-	StatusMovedPermanently  = 301
-	StatusFound             = 302
-	StatusSeeOther          = 303
-	StatusNotModified       = 304
-	StatusUseProxy          = 305
-	StatusTemporaryRedirect = 307
+	StatusMultipleChoices   = 300 // RFC 7231, 6.4.1
+	StatusMovedPermanently  = 301 // RFC 7231, 6.4.2
+	StatusFound             = 302 // RFC 7231, 6.4.3
+	StatusSeeOther          = 303 // RFC 7231, 6.4.4
+	StatusNotModified       = 304 // RFC 7232, 4.1
+	StatusUseProxy          = 305 // RFC 7231, 6.4.5
+	_                       = 306 // RFC 7231, 6.4.6 (Unused)
+	StatusTemporaryRedirect = 307 // RFC 7231, 6.4.7
+	StatusPermanentRedirect = 308 // RFC 7538, 3
 
-	StatusBadRequest                   = 400
-	StatusUnauthorized                 = 401
-	StatusPaymentRequired              = 402
-	StatusForbidden                    = 403
-	StatusNotFound                     = 404
-	StatusMethodNotAllowed             = 405
-	StatusNotAcceptable                = 406
-	StatusProxyAuthRequired            = 407
-	StatusRequestTimeout               = 408
-	StatusConflict                     = 409
-	StatusGone                         = 410
-	StatusLengthRequired               = 411
-	StatusPreconditionFailed           = 412
-	StatusRequestEntityTooLarge        = 413
-	StatusRequestURITooLong            = 414
-	StatusUnsupportedMediaType         = 415
-	StatusRequestedRangeNotSatisfiable = 416
-	StatusExpectationFailed            = 417
-	StatusTeapot                       = 418
-	StatusPreconditionRequired         = 428
-	StatusTooManyRequests              = 429
-	StatusRequestHeaderFieldsTooLarge  = 431
-	StatusUnavailableForLegalReasons   = 451
+	StatusBadRequest                   = 400 // RFC 7231, 6.5.1
+	StatusUnauthorized                 = 401 // RFC 7235, 3.1
+	StatusPaymentRequired              = 402 // RFC 7231, 6.5.2
+	StatusForbidden                    = 403 // RFC 7231, 6.5.3
+	StatusNotFound                     = 404 // RFC 7231, 6.5.4
+	StatusMethodNotAllowed             = 405 // RFC 7231, 6.5.5
+	StatusNotAcceptable                = 406 // RFC 7231, 6.5.6
+	StatusProxyAuthRequired            = 407 // RFC 7235, 3.2
+	StatusRequestTimeout               = 408 // RFC 7231, 6.5.7
+	StatusConflict                     = 409 // RFC 7231, 6.5.8
+	StatusGone                         = 410 // RFC 7231, 6.5.9
+	StatusLengthRequired               = 411 // RFC 7231, 6.5.10
+	StatusPreconditionFailed           = 412 // RFC 7232, 4.2
+	StatusRequestEntityTooLarge        = 413 // RFC 7231, 6.5.11
+	StatusRequestURITooLong            = 414 // RFC 7231, 6.5.12
+	StatusUnsupportedMediaType         = 415 // RFC 7231, 6.5.13
+	StatusRequestedRangeNotSatisfiable = 416 // RFC 7233, 4.4
+	StatusExpectationFailed            = 417 // RFC 7231, 6.5.14
+	StatusTeapot                       = 418 // RFC 7168, 2.3.3
+	StatusUnprocessableEntity          = 422 // RFC 4918, 11.2
+	StatusLocked                       = 423 // RFC 4918, 11.3
+	StatusFailedDependency             = 424 // RFC 4918, 11.4
+	StatusUpgradeRequired              = 426 // RFC 7231, 6.5.15
+	StatusPreconditionRequired         = 428 // RFC 6585, 3
+	StatusTooManyRequests              = 429 // RFC 6585, 4
+	StatusRequestHeaderFieldsTooLarge  = 431 // RFC 6585, 5
+	StatusUnavailableForLegalReasons   = 451 // RFC 7725, 3
 
-	StatusInternalServerError           = 500
-	StatusNotImplemented                = 501
-	StatusBadGateway                    = 502
-	StatusServiceUnavailable            = 503
-	StatusGatewayTimeout                = 504
-	StatusHTTPVersionNotSupported       = 505
-	StatusNetworkAuthenticationRequired = 511
+	StatusInternalServerError           = 500 // RFC 7231, 6.6.1
+	StatusNotImplemented                = 501 // RFC 7231, 6.6.2
+	StatusBadGateway                    = 502 // RFC 7231, 6.6.3
+	StatusServiceUnavailable            = 503 // RFC 7231, 6.6.4
+	StatusGatewayTimeout                = 504 // RFC 7231, 6.6.5
+	StatusHTTPVersionNotSupported       = 505 // RFC 7231, 6.6.6
+	StatusVariantAlsoNegotiates         = 506 // RFC 2295, 8.1
+	StatusInsufficientStorage           = 507 // RFC 4918, 11.5
+	StatusLoopDetected                  = 508 // RFC 5842, 7.2
+	StatusNotExtended                   = 510 // RFC 2774, 7
+	StatusNetworkAuthenticationRequired = 511 // RFC 6585, 6
 )
 
 var statusText = map[int]string{
 	StatusContinue:           "Continue",
 	StatusSwitchingProtocols: "Switching Protocols",
+	StatusProcessing:         "Processing",
 
 	StatusOK:                   "OK",
 	StatusCreated:              "Created",
@@ -69,6 +85,9 @@ var statusText = map[int]string{
 	StatusNoContent:            "No Content",
 	StatusResetContent:         "Reset Content",
 	StatusPartialContent:       "Partial Content",
+	StatusMultiStatus:          "Multi-Status",
+	StatusAlreadyReported:      "Already Reported",
+	StatusIMUsed:               "IM Used",
 
 	StatusMultipleChoices:   "Multiple Choices",
 	StatusMovedPermanently:  "Moved Permanently",
@@ -77,6 +96,7 @@ var statusText = map[int]string{
 	StatusNotModified:       "Not Modified",
 	StatusUseProxy:          "Use Proxy",
 	StatusTemporaryRedirect: "Temporary Redirect",
+	StatusPermanentRedirect: "Permanent Redirect",
 
 	StatusBadRequest:                   "Bad Request",
 	StatusUnauthorized:                 "Unauthorized",
@@ -97,6 +117,10 @@ var statusText = map[int]string{
 	StatusRequestedRangeNotSatisfiable: "Requested Range Not Satisfiable",
 	StatusExpectationFailed:            "Expectation Failed",
 	StatusTeapot:                       "I'm a teapot",
+	StatusUnprocessableEntity:          "Unprocessable Entity",
+	StatusLocked:                       "Locked",
+	StatusFailedDependency:             "Failed Dependency",
+	StatusUpgradeRequired:              "Upgrade Required",
 	StatusPreconditionRequired:         "Precondition Required",
 	StatusTooManyRequests:              "Too Many Requests",
 	StatusRequestHeaderFieldsTooLarge:  "Request Header Fields Too Large",
@@ -108,6 +132,10 @@ var statusText = map[int]string{
 	StatusServiceUnavailable:            "Service Unavailable",
 	StatusGatewayTimeout:                "Gateway Timeout",
 	StatusHTTPVersionNotSupported:       "HTTP Version Not Supported",
+	StatusVariantAlsoNegotiates:         "Variant Also Negotiates",
+	StatusInsufficientStorage:           "Insufficient Storage",
+	StatusLoopDetected:                  "Loop Detected",
+	StatusNotExtended:                   "Not Extended",
 	StatusNetworkAuthenticationRequired: "Network Authentication Required",
 }
 
diff --git a/libgo/go/net/http/transfer.go b/libgo/go/net/http/transfer.go
index 6e59af8f6f4..c653467098c 100644
--- a/libgo/go/net/http/transfer.go
+++ b/libgo/go/net/http/transfer.go
@@ -17,6 +17,8 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+
+	"golang_org/x/net/lex/httplex"
 )
 
 // ErrLineTooLong is returned when reading request or response bodies
@@ -276,7 +278,7 @@ func (t *transferReader) protoAtLeast(m, n int) bool {
 }
 
 // bodyAllowedForStatus reports whether a given response status code
-// permits a body.  See RFC2616, section 4.4.
+// permits a body. See RFC 2616, section 4.4.
 func bodyAllowedForStatus(status int) bool {
 	switch {
 	case status >= 100 && status <= 199:
@@ -368,7 +370,7 @@ func readTransfer(msg interface{}, r *bufio.Reader) (err error) {
 
 	// If there is no Content-Length or chunked Transfer-Encoding on a *Response
 	// and the status is not 1xx, 204 or 304, then the body is unbounded.
-	// See RFC2616, section 4.4.
+	// See RFC 2616, section 4.4.
 	switch msg.(type) {
 	case *Response:
 		if realLength == -1 &&
@@ -379,7 +381,7 @@ func readTransfer(msg interface{}, r *bufio.Reader) (err error) {
 		}
 	}
 
-	// Prepare body reader.  ContentLength < 0 means chunked encoding
+	// Prepare body reader. ContentLength < 0 means chunked encoding
 	// or close connection when finished, since multipart is not supported yet
 	switch {
 	case chunked(t.TransferEncoding):
@@ -558,21 +560,19 @@ func fixLength(isResponse bool, status int, requestMethod string, header Header,
 func shouldClose(major, minor int, header Header, removeCloseHeader bool) bool {
 	if major < 1 {
 		return true
-	} else if major == 1 && minor == 0 {
-		vv := header["Connection"]
-		if headerValuesContainsToken(vv, "close") || !headerValuesContainsToken(vv, "keep-alive") {
-			return true
-		}
-		return false
-	} else {
-		if headerValuesContainsToken(header["Connection"], "close") {
-			if removeCloseHeader {
-				header.Del("Connection")
-			}
-			return true
-		}
 	}
-	return false
+
+	conv := header["Connection"]
+	hasClose := httplex.HeaderValuesContainsToken(conv, "close")
+	if major == 1 && minor == 0 {
+		return hasClose || !httplex.HeaderValuesContainsToken(conv, "keep-alive")
+	}
+
+	if hasClose && removeCloseHeader {
+		header.Del("Connection")
+	}
+
+	return hasClose
 }
 
 // Parse the trailer header
@@ -729,11 +729,11 @@ func (b *body) readTrailer() error {
 	}
 
 	// Make sure there's a header terminator coming up, to prevent
-	// a DoS with an unbounded size Trailer.  It's not easy to
+	// a DoS with an unbounded size Trailer. It's not easy to
 	// slip in a LimitReader here, as textproto.NewReader requires
-	// a concrete *bufio.Reader.  Also, we can't get all the way
+	// a concrete *bufio.Reader. Also, we can't get all the way
 	// back up to our conn's LimitedReader that *might* be backing
-	// this bufio.Reader.  Instead, a hack: we iteratively Peek up
+	// this bufio.Reader. Instead, a hack: we iteratively Peek up
 	// to the bufio.Reader's max size, looking for a double CRLF.
 	// This limits the trailer to the underlying buffer size, typically 4kB.
 	if !seeUpcomingDoubleCRLF(b.r) {
diff --git a/libgo/go/net/http/transport.go b/libgo/go/net/http/transport.go
index baf71d5e85e..9164d0d827c 100644
--- a/libgo/go/net/http/transport.go
+++ b/libgo/go/net/http/transport.go
@@ -12,17 +12,22 @@ package http
 import (
 	"bufio"
 	"compress/gzip"
+	"container/list"
+	"context"
 	"crypto/tls"
 	"errors"
 	"fmt"
 	"io"
 	"log"
 	"net"
+	"net/http/httptrace"
 	"net/url"
 	"os"
 	"strings"
 	"sync"
 	"time"
+
+	"golang_org/x/net/lex/httplex"
 )
 
 // DefaultTransport is the default implementation of Transport and is
@@ -32,10 +37,12 @@ import (
 // $no_proxy) environment variables.
 var DefaultTransport RoundTripper = &Transport{
 	Proxy: ProxyFromEnvironment,
-	Dial: (&net.Dialer{
+	DialContext: (&net.Dialer{
 		Timeout:   30 * time.Second,
 		KeepAlive: 30 * time.Second,
-	}).Dial,
+	}).DialContext,
+	MaxIdleConns:          100,
+	IdleConnTimeout:       90 * time.Second,
 	TLSHandshakeTimeout:   10 * time.Second,
 	ExpectContinueTimeout: 1 * time.Second,
 }
@@ -63,9 +70,10 @@ const DefaultMaxIdleConnsPerHost = 2
 // See the package docs for more about HTTP/2.
 type Transport struct {
 	idleMu     sync.Mutex
-	wantIdle   bool // user has requested to close all idle conns
-	idleConn   map[connectMethodKey][]*persistConn
+	wantIdle   bool                                // user has requested to close all idle conns
+	idleConn   map[connectMethodKey][]*persistConn // most recently used at end
 	idleConnCh map[connectMethodKey]chan *persistConn
+	idleLRU    connLRU
 
 	reqMu       sync.Mutex
 	reqCanceler map[*Request]func()
@@ -79,9 +87,16 @@ type Transport struct {
 	// If Proxy is nil or returns a nil *URL, no proxy is used.
 	Proxy func(*Request) (*url.URL, error)
 
-	// Dial specifies the dial function for creating unencrypted
-	// TCP connections.
-	// If Dial is nil, net.Dial is used.
+	// DialContext specifies the dial function for creating unencrypted TCP connections.
+	// If DialContext is nil (and the deprecated Dial below is also nil),
+	// then the transport dials using package net.
+	DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
+
+	// Dial specifies the dial function for creating unencrypted TCP connections.
+	//
+	// Deprecated: Use DialContext instead, which allows the transport
+	// to cancel dials as soon as they are no longer needed.
+	// If both are set, DialContext takes priority.
 	Dial func(network, addr string) (net.Conn, error)
 
 	// DialTLS specifies an optional dial function for creating
@@ -117,11 +132,21 @@ type Transport struct {
 	// uncompressed.
 	DisableCompression bool
 
+	// MaxIdleConns controls the maximum number of idle (keep-alive)
+	// connections across all hosts. Zero means no limit.
+	MaxIdleConns int
+
 	// MaxIdleConnsPerHost, if non-zero, controls the maximum idle
-	// (keep-alive) to keep per-host.  If zero,
+	// (keep-alive) connections to keep per-host. If zero,
 	// DefaultMaxIdleConnsPerHost is used.
 	MaxIdleConnsPerHost int
 
+	// IdleConnTimeout is the maximum amount of time an idle
+	// (keep-alive) connection will remain idle before closing
+	// itself.
+	// Zero means no limit.
+	IdleConnTimeout time.Duration
+
 	// ResponseHeaderTimeout, if non-zero, specifies the amount of
 	// time to wait for a server's response headers after fully
 	// writing the request (including its body, if any). This
@@ -137,7 +162,7 @@ type Transport struct {
 
 	// TLSNextProto specifies how the Transport switches to an
 	// alternate protocol (such as HTTP/2) after a TLS NPN/ALPN
-	// protocol negotiation.  If Transport dials an TLS connection
+	// protocol negotiation. If Transport dials an TLS connection
 	// with a non-empty protocol name and TLSNextProto contains a
 	// map entry for that key (such as "h2"), then the func is
 	// called with the request's authority (such as "example.com"
@@ -146,13 +171,18 @@ type Transport struct {
 	// If TLSNextProto is nil, HTTP/2 support is enabled automatically.
 	TLSNextProto map[string]func(authority string, c *tls.Conn) RoundTripper
 
+	// MaxResponseHeaderBytes specifies a limit on how many
+	// response bytes are allowed in the server's response
+	// header.
+	//
+	// Zero means to use a default limit.
+	MaxResponseHeaderBytes int64
+
 	// nextProtoOnce guards initialization of TLSNextProto and
 	// h2transport (via onceSetNextProtoDefaults)
 	nextProtoOnce sync.Once
 	h2transport   *http2Transport // non-nil if http2 wired up
 
-	// TODO: tunable on global max cached connections
-	// TODO: tunable on timeout on cached connections
 	// TODO: tunable on max per-host TCP dials in flight (Issue 13957)
 }
 
@@ -167,25 +197,34 @@ func (t *Transport) onceSetNextProtoDefaults() {
 		// Transport.
 		return
 	}
-	if t.TLSClientConfig != nil {
-		// Be conservative for now (for Go 1.6) at least and
-		// don't automatically enable http2 if they've
-		// specified a custom TLS config. Let them opt-in
-		// themselves via http2.ConfigureTransport so we don't
-		// surprise them by modifying their tls.Config.
-		// Issue 14275.
-		return
-	}
-	if t.ExpectContinueTimeout != 0 {
-		// Unsupported in http2, so disable http2 for now.
-		// Issue 13851.
+	if t.TLSClientConfig != nil || t.Dial != nil || t.DialTLS != nil {
+		// Be conservative and don't automatically enable
+		// http2 if they've specified a custom TLS config or
+		// custom dialers. Let them opt-in themselves via
+		// http2.ConfigureTransport so we don't surprise them
+		// by modifying their tls.Config. Issue 14275.
 		return
 	}
 	t2, err := http2configureTransport(t)
 	if err != nil {
 		log.Printf("Error enabling Transport HTTP/2 support: %v", err)
-	} else {
-		t.h2transport = t2
+		return
+	}
+	t.h2transport = t2
+
+	// Auto-configure the http2.Transport's MaxHeaderListSize from
+	// the http.Transport's MaxResponseHeaderBytes. They don't
+	// exactly mean the same thing, but they're close.
+	//
+	// TODO: also add this to x/net/http2.Configure Transport, behind
+	// a +build go1.7 build tag:
+	if limit1 := t.MaxResponseHeaderBytes; limit1 != 0 && t2.MaxHeaderListSize == 0 {
+		const h2max = 1<<32 - 1
+		if limit1 >= h2max {
+			t2.MaxHeaderListSize = h2max
+		} else {
+			t2.MaxHeaderListSize = uint32(limit1)
+		}
 	}
 }
 
@@ -212,6 +251,9 @@ func ProxyFromEnvironment(req *Request) (*url.URL, error) {
 	}
 	if proxy == "" {
 		proxy = httpProxyEnv.Get()
+		if proxy != "" && os.Getenv("REQUEST_METHOD") != "" {
+			return nil, errors.New("net/http: refusing to use HTTP_PROXY value in CGI environment; see golang.org/s/cgihttpproxy")
+		}
 	}
 	if proxy == "" {
 		return nil, nil
@@ -245,8 +287,9 @@ func ProxyURL(fixedURL *url.URL) func(*Request) (*url.URL, error) {
 // transportRequest is a wrapper around a *Request that adds
 // optional extra headers to write.
 type transportRequest struct {
-	*Request        // original request, not to be mutated
-	extra    Header // extra headers to write, or nil
+	*Request                        // original request, not to be mutated
+	extra    Header                 // extra headers to write, or nil
+	trace    *httptrace.ClientTrace // optional
 }
 
 func (tr *transportRequest) extraHeaders() Header {
@@ -262,6 +305,9 @@ func (tr *transportRequest) extraHeaders() Header {
 // and redirects), see Get, Post, and the Client type.
 func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 	t.nextProtoOnce.Do(t.onceSetNextProtoDefaults)
+	ctx := req.Context()
+	trace := httptrace.ContextClientTrace(ctx)
+
 	if req.URL == nil {
 		req.closeBody()
 		return nil, errors.New("http: nil Request.URL")
@@ -270,18 +316,32 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 		req.closeBody()
 		return nil, errors.New("http: nil Request.Header")
 	}
+	scheme := req.URL.Scheme
+	isHTTP := scheme == "http" || scheme == "https"
+	if isHTTP {
+		for k, vv := range req.Header {
+			if !httplex.ValidHeaderFieldName(k) {
+				return nil, fmt.Errorf("net/http: invalid header field name %q", k)
+			}
+			for _, v := range vv {
+				if !httplex.ValidHeaderFieldValue(v) {
+					return nil, fmt.Errorf("net/http: invalid header field value %q for key %v", v, k)
+				}
+			}
+		}
+	}
 	// TODO(bradfitz): switch to atomic.Value for this map instead of RWMutex
 	t.altMu.RLock()
-	altRT := t.altProto[req.URL.Scheme]
+	altRT := t.altProto[scheme]
 	t.altMu.RUnlock()
 	if altRT != nil {
 		if resp, err := altRT.RoundTrip(req); err != ErrSkipAltProtocol {
 			return resp, err
 		}
 	}
-	if s := req.URL.Scheme; s != "http" && s != "https" {
+	if !isHTTP {
 		req.closeBody()
-		return nil, &badStringError{"unsupported protocol scheme", s}
+		return nil, &badStringError{"unsupported protocol scheme", scheme}
 	}
 	if req.Method != "" && !validMethod(req.Method) {
 		return nil, fmt.Errorf("net/http: invalid method %q", req.Method)
@@ -293,7 +353,7 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 
 	for {
 		// treq gets modified by roundTrip, so we need to recreate for each retry.
-		treq := &transportRequest{Request: req}
+		treq := &transportRequest{Request: req, trace: trace}
 		cm, err := t.connectMethodForRequest(treq)
 		if err != nil {
 			req.closeBody()
@@ -302,9 +362,9 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 
 		// Get the cached or newly-created connection to either the
 		// host (for http or https), the http proxy, or the http proxy
-		// pre-CONNECTed to https server.  In any case, we'll be ready
+		// pre-CONNECTed to https server. In any case, we'll be ready
 		// to send it requests.
-		pconn, err := t.getConn(req, cm)
+		pconn, err := t.getConn(treq, cm)
 		if err != nil {
 			t.setReqCanceler(req, nil)
 			req.closeBody()
@@ -322,46 +382,47 @@ func (t *Transport) RoundTrip(req *Request) (*Response, error) {
 		if err == nil {
 			return resp, nil
 		}
-		if err := checkTransportResend(err, req, pconn); err != nil {
+		if !pconn.shouldRetryRequest(req, err) {
 			return nil, err
 		}
 		testHookRoundTripRetried()
 	}
 }
 
-// checkTransportResend checks whether a failed HTTP request can be
-// resent on a new connection. The non-nil input error is the error from
-// roundTrip, which might be wrapped in a beforeRespHeaderError error.
-//
-// The return value is err or the unwrapped error inside a
-// beforeRespHeaderError.
-func checkTransportResend(err error, req *Request, pconn *persistConn) error {
-	brhErr, ok := err.(beforeRespHeaderError)
-	if !ok {
-		return err
+// shouldRetryRequest reports whether we should retry sending a failed
+// HTTP request on a new connection. The non-nil input error is the
+// error from roundTrip.
+func (pc *persistConn) shouldRetryRequest(req *Request, err error) bool {
+	if err == errMissingHost {
+		// User error.
+		return false
 	}
-	err = brhErr.error // unwrap the custom error in case we return it
-	if err != errMissingHost && pconn.isReused() && req.isReplayable() {
-		// If we try to reuse a connection that the server is in the process of
-		// closing, we may end up successfully writing out our request (or a
-		// portion of our request) only to find a connection error when we try to
-		// read from (or finish writing to) the socket.
-
-		// There can be a race between the socket pool checking whether a socket
-		// is still connected, receiving the FIN, and sending/reading data on a
-		// reused socket. If we receive the FIN between the connectedness check
-		// and writing/reading from the socket, we may first learn the socket is
-		// disconnected when we get a ERR_SOCKET_NOT_CONNECTED. This will most
-		// likely happen when trying to retrieve its IP address. See
-		// http://crbug.com/105824 for more details.
-
-		// We resend a request only if we reused a keep-alive connection and did
-		// not yet receive any header data. This automatically prevents an
-		// infinite resend loop because we'll run out of the cached keep-alive
-		// connections eventually.
-		return nil
+	if !pc.isReused() {
+		// This was a fresh connection. There's no reason the server
+		// should've hung up on us.
+		//
+		// Also, if we retried now, we could loop forever
+		// creating new connections and retrying if the server
+		// is just hanging up on us because it doesn't like
+		// our request (as opposed to sending an error).
+		return false
 	}
-	return err
+	if !req.isReplayable() {
+		// Don't retry non-idempotent requests.
+
+		// TODO: swap the nothingWrittenError and isReplayable checks,
+		// putting the "if nothingWrittenError => return true" case
+		// first, per golang.org/issue/15723
+		return false
+	}
+	if _, ok := err.(nothingWrittenError); ok {
+		// We never wrote anything, so it's safe to retry.
+		return true
+	}
+	if err == errServerClosedIdle || err == errServerClosedConn {
+		return true
+	}
+	return false // conservatively
 }
 
 // ErrSkipAltProtocol is a sentinel error value defined by Transport.RegisterProtocol.
@@ -400,6 +461,7 @@ func (t *Transport) CloseIdleConnections() {
 	t.idleConn = nil
 	t.idleConnCh = nil
 	t.wantIdle = true
+	t.idleLRU = connLRU{}
 	t.idleMu.Unlock()
 	for _, conns := range m {
 		for _, pconn := range conns {
@@ -414,7 +476,7 @@ func (t *Transport) CloseIdleConnections() {
 // CancelRequest cancels an in-flight request by closing its connection.
 // CancelRequest should only be called after RoundTrip has returned.
 //
-// Deprecated: Use Request.Cancel instead. CancelRequest can not cancel
+// Deprecated: Use Request.Cancel instead. CancelRequest cannot cancel
 // HTTP/2 requests.
 func (t *Transport) CancelRequest(req *Request) {
 	t.reqMu.Lock()
@@ -500,9 +562,12 @@ var (
 	errConnBroken         = errors.New("http: putIdleConn: connection is in bad state")
 	errWantIdle           = errors.New("http: putIdleConn: CloseIdleConnections was called")
 	errTooManyIdle        = errors.New("http: putIdleConn: too many idle connections")
+	errTooManyIdleHost    = errors.New("http: putIdleConn: too many idle connections for host")
 	errCloseIdleConns     = errors.New("http: CloseIdleConnections called")
 	errReadLoopExiting    = errors.New("http: persistConn.readLoop exiting")
-	errServerClosedIdle   = errors.New("http: server closed idle conn")
+	errServerClosedIdle   = errors.New("http: server closed idle connection")
+	errServerClosedConn   = errors.New("http: server closed connection")
+	errIdleConnTimeout    = errors.New("http: idle connection timeout")
 )
 
 func (t *Transport) putOrCloseIdleConn(pconn *persistConn) {
@@ -511,6 +576,13 @@ func (t *Transport) putOrCloseIdleConn(pconn *persistConn) {
 	}
 }
 
+func (t *Transport) maxIdleConnsPerHost() int {
+	if v := t.MaxIdleConnsPerHost; v != 0 {
+		return v
+	}
+	return DefaultMaxIdleConnsPerHost
+}
+
 // tryPutIdleConn adds pconn to the list of idle persistent connections awaiting
 // a new request.
 // If pconn is no longer needed or not in a good state, tryPutIdleConn returns
@@ -523,13 +595,11 @@ func (t *Transport) tryPutIdleConn(pconn *persistConn) error {
 	if pconn.isBroken() {
 		return errConnBroken
 	}
-	key := pconn.cacheKey
-	max := t.MaxIdleConnsPerHost
-	if max == 0 {
-		max = DefaultMaxIdleConnsPerHost
-	}
 	pconn.markReused()
+	key := pconn.cacheKey
+
 	t.idleMu.Lock()
+	defer t.idleMu.Unlock()
 
 	waitingDialer := t.idleConnCh[key]
 	select {
@@ -537,9 +607,8 @@ func (t *Transport) tryPutIdleConn(pconn *persistConn) error {
 		// We're done with this pconn and somebody else is
 		// currently waiting for a conn of this type (they're
 		// actively dialing, but this conn is ready
-		// first). Chrome calls this socket late binding.  See
+		// first). Chrome calls this socket late binding. See
 		// https://insouciant.org/tech/connection-management-in-chromium/
-		t.idleMu.Unlock()
 		return nil
 	default:
 		if waitingDialer != nil {
@@ -549,23 +618,35 @@ func (t *Transport) tryPutIdleConn(pconn *persistConn) error {
 		}
 	}
 	if t.wantIdle {
-		t.idleMu.Unlock()
 		return errWantIdle
 	}
 	if t.idleConn == nil {
 		t.idleConn = make(map[connectMethodKey][]*persistConn)
 	}
-	if len(t.idleConn[key]) >= max {
-		t.idleMu.Unlock()
-		return errTooManyIdle
+	idles := t.idleConn[key]
+	if len(idles) >= t.maxIdleConnsPerHost() {
+		return errTooManyIdleHost
 	}
-	for _, exist := range t.idleConn[key] {
+	for _, exist := range idles {
 		if exist == pconn {
 			log.Fatalf("dup idle pconn %p in freelist", pconn)
 		}
 	}
-	t.idleConn[key] = append(t.idleConn[key], pconn)
-	t.idleMu.Unlock()
+	t.idleConn[key] = append(idles, pconn)
+	t.idleLRU.add(pconn)
+	if t.MaxIdleConns != 0 && t.idleLRU.len() > t.MaxIdleConns {
+		oldest := t.idleLRU.removeOldest()
+		oldest.close(errTooManyIdle)
+		t.removeIdleConnLocked(oldest)
+	}
+	if t.IdleConnTimeout > 0 {
+		if pconn.idleTimer != nil {
+			pconn.idleTimer.Reset(t.IdleConnTimeout)
+		} else {
+			pconn.idleTimer = time.AfterFunc(t.IdleConnTimeout, pconn.closeConnIfStillIdle)
+		}
+	}
+	pconn.idleAt = time.Now()
 	return nil
 }
 
@@ -591,29 +672,75 @@ func (t *Transport) getIdleConnCh(cm connectMethod) chan *persistConn {
 	return ch
 }
 
-func (t *Transport) getIdleConn(cm connectMethod) (pconn *persistConn) {
+func (t *Transport) getIdleConn(cm connectMethod) (pconn *persistConn, idleSince time.Time) {
 	key := cm.key()
 	t.idleMu.Lock()
 	defer t.idleMu.Unlock()
-	if t.idleConn == nil {
-		return nil
-	}
 	for {
 		pconns, ok := t.idleConn[key]
 		if !ok {
-			return nil
+			return nil, time.Time{}
 		}
 		if len(pconns) == 1 {
 			pconn = pconns[0]
 			delete(t.idleConn, key)
 		} else {
-			// 2 or more cached connections; pop last
-			// TODO: queue?
+			// 2 or more cached connections; use the most
+			// recently used one at the end.
 			pconn = pconns[len(pconns)-1]
 			t.idleConn[key] = pconns[:len(pconns)-1]
 		}
-		if !pconn.isBroken() {
-			return
+		t.idleLRU.remove(pconn)
+		if pconn.isBroken() {
+			// There is a tiny window where this is
+			// possible, between the connecting dying and
+			// the persistConn readLoop calling
+			// Transport.removeIdleConn. Just skip it and
+			// carry on.
+			continue
+		}
+		if pconn.idleTimer != nil && !pconn.idleTimer.Stop() {
+			// We picked this conn at the ~same time it
+			// was expiring and it's trying to close
+			// itself in another goroutine. Don't use it.
+			continue
+		}
+		return pconn, pconn.idleAt
+	}
+}
+
+// removeIdleConn marks pconn as dead.
+func (t *Transport) removeIdleConn(pconn *persistConn) {
+	t.idleMu.Lock()
+	defer t.idleMu.Unlock()
+	t.removeIdleConnLocked(pconn)
+}
+
+// t.idleMu must be held.
+func (t *Transport) removeIdleConnLocked(pconn *persistConn) {
+	if pconn.idleTimer != nil {
+		pconn.idleTimer.Stop()
+	}
+	t.idleLRU.remove(pconn)
+	key := pconn.cacheKey
+	pconns, _ := t.idleConn[key]
+	switch len(pconns) {
+	case 0:
+		// Nothing
+	case 1:
+		if pconns[0] == pconn {
+			delete(t.idleConn, key)
+		}
+	default:
+		for i, v := range pconns {
+			if v != pconn {
+				continue
+			}
+			// Slide down, keeping most recently-used
+			// conns at the end.
+			copy(pconns[i:], pconns[i+1:])
+			t.idleConn[key] = pconns[:len(pconns)-1]
+			break
 		}
 	}
 }
@@ -650,7 +777,12 @@ func (t *Transport) replaceReqCanceler(r *Request, fn func()) bool {
 	return true
 }
 
-func (t *Transport) dial(network, addr string) (net.Conn, error) {
+var zeroDialer net.Dialer
+
+func (t *Transport) dial(ctx context.Context, network, addr string) (net.Conn, error) {
+	if t.DialContext != nil {
+		return t.DialContext(ctx, network, addr)
+	}
 	if t.Dial != nil {
 		c, err := t.Dial(network, addr)
 		if c == nil && err == nil {
@@ -658,15 +790,24 @@ func (t *Transport) dial(network, addr string) (net.Conn, error) {
 		}
 		return c, err
 	}
-	return net.Dial(network, addr)
+	return zeroDialer.DialContext(ctx, network, addr)
 }
 
 // getConn dials and creates a new persistConn to the target as
-// specified in the connectMethod.  This includes doing a proxy CONNECT
+// specified in the connectMethod. This includes doing a proxy CONNECT
 // and/or setting up TLS.  If this doesn't return an error, the persistConn
 // is ready to write requests to.
-func (t *Transport) getConn(req *Request, cm connectMethod) (*persistConn, error) {
-	if pc := t.getIdleConn(cm); pc != nil {
+func (t *Transport) getConn(treq *transportRequest, cm connectMethod) (*persistConn, error) {
+	req := treq.Request
+	trace := treq.trace
+	ctx := req.Context()
+	if trace != nil && trace.GetConn != nil {
+		trace.GetConn(cm.addr())
+	}
+	if pc, idleSince := t.getIdleConn(cm); pc != nil {
+		if trace != nil && trace.GotConn != nil {
+			trace.GotConn(pc.gotIdleConnTrace(idleSince))
+		}
 		// set request canceler to some non-nil function so we
 		// can detect whether it was cleared between now and when
 		// we enter roundTrip
@@ -699,7 +840,7 @@ func (t *Transport) getConn(req *Request, cm connectMethod) (*persistConn, error
 	t.setReqCanceler(req, func() { close(cancelc) })
 
 	go func() {
-		pc, err := t.dialConn(cm)
+		pc, err := t.dialConn(ctx, cm)
 		dialc <- dialRes{pc, err}
 	}()
 
@@ -707,7 +848,26 @@ func (t *Transport) getConn(req *Request, cm connectMethod) (*persistConn, error
 	select {
 	case v := <-dialc:
 		// Our dial finished.
-		return v.pc, v.err
+		if v.pc != nil {
+			if trace != nil && trace.GotConn != nil && v.pc.alt == nil {
+				trace.GotConn(httptrace.GotConnInfo{Conn: v.pc.conn})
+			}
+			return v.pc, nil
+		}
+		// Our dial failed. See why to return a nicer error
+		// value.
+		select {
+		case <-req.Cancel:
+		case <-req.Context().Done():
+		case <-cancelc:
+		default:
+			// It wasn't an error due to cancelation, so
+			// return the original error message:
+			return nil, v.err
+		}
+		// It was an error due to cancelation, so prioritize that
+		// error value. (Issue 16049)
+		return nil, errRequestCanceledConn
 	case pc := <-idleConnCh:
 		// Another request finished first and its net.Conn
 		// became available before our dial. Or somebody
@@ -715,24 +875,31 @@ func (t *Transport) getConn(req *Request, cm connectMethod) (*persistConn, error
 		// But our dial is still going, so give it away
 		// when it finishes:
 		handlePendingDial()
+		if trace != nil && trace.GotConn != nil {
+			trace.GotConn(httptrace.GotConnInfo{Conn: pc.conn, Reused: pc.isReused()})
+		}
 		return pc, nil
 	case <-req.Cancel:
 		handlePendingDial()
 		return nil, errRequestCanceledConn
+	case <-req.Context().Done():
+		handlePendingDial()
+		return nil, errRequestCanceledConn
 	case <-cancelc:
 		handlePendingDial()
 		return nil, errRequestCanceledConn
 	}
 }
 
-func (t *Transport) dialConn(cm connectMethod) (*persistConn, error) {
+func (t *Transport) dialConn(ctx context.Context, cm connectMethod) (*persistConn, error) {
 	pconn := &persistConn{
-		t:          t,
-		cacheKey:   cm.key(),
-		reqch:      make(chan requestAndChan, 1),
-		writech:    make(chan writeRequest, 1),
-		closech:    make(chan struct{}),
-		writeErrCh: make(chan error, 1),
+		t:             t,
+		cacheKey:      cm.key(),
+		reqch:         make(chan requestAndChan, 1),
+		writech:       make(chan writeRequest, 1),
+		closech:       make(chan struct{}),
+		writeErrCh:    make(chan error, 1),
+		writeLoopDone: make(chan struct{}),
 	}
 	tlsDial := t.DialTLS != nil && cm.targetScheme == "https" && cm.proxyURL == nil
 	if tlsDial {
@@ -755,7 +922,7 @@ func (t *Transport) dialConn(cm connectMethod) (*persistConn, error) {
 			pconn.tlsState = &cs
 		}
 	} else {
-		conn, err := t.dial("tcp", cm.addr())
+		conn, err := t.dial(ctx, "tcp", cm.addr())
 		if err != nil {
 			if cm.proxyURL != nil {
 				err = fmt.Errorf("http: error connecting to proxy %s: %v", cm.proxyURL, err)
@@ -848,13 +1015,29 @@ func (t *Transport) dialConn(cm connectMethod) (*persistConn, error) {
 		}
 	}
 
-	pconn.br = bufio.NewReader(noteEOFReader{pconn.conn, &pconn.sawEOF})
-	pconn.bw = bufio.NewWriter(pconn.conn)
+	pconn.br = bufio.NewReader(pconn)
+	pconn.bw = bufio.NewWriter(persistConnWriter{pconn})
 	go pconn.readLoop()
 	go pconn.writeLoop()
 	return pconn, nil
 }
 
+// persistConnWriter is the io.Writer written to by pc.bw.
+// It accumulates the number of bytes written to the underlying conn,
+// so the retry logic can determine whether any bytes made it across
+// the wire.
+// This is exactly 1 pointer field wide so it can go into an interface
+// without allocation.
+type persistConnWriter struct {
+	pc *persistConn
+}
+
+func (w persistConnWriter) Write(p []byte) (n int, err error) {
+	n, err = w.pc.conn.Write(p)
+	w.pc.nwrite += int64(n)
+	return
+}
+
 // useProxy reports whether requests to addr should use a proxy,
 // according to the NO_PROXY or no_proxy environment variable.
 // addr is always a canonicalAddr with a host and port.
@@ -978,28 +1161,36 @@ func (k connectMethodKey) String() string {
 // (but may be used for non-keep-alive requests as well)
 type persistConn struct {
 	// alt optionally specifies the TLS NextProto RoundTripper.
-	// This is used for HTTP/2 today and future protocol laters.
+	// This is used for HTTP/2 today and future protocols later.
 	// If it's non-nil, the rest of the fields are unused.
 	alt RoundTripper
 
-	t        *Transport
-	cacheKey connectMethodKey
-	conn     net.Conn
-	tlsState *tls.ConnectionState
-	br       *bufio.Reader       // from conn
-	sawEOF   bool                // whether we've seen EOF from conn; owned by readLoop
-	bw       *bufio.Writer       // to conn
-	reqch    chan requestAndChan // written by roundTrip; read by readLoop
-	writech  chan writeRequest   // written by roundTrip; read by writeLoop
-	closech  chan struct{}       // closed when conn closed
-	isProxy  bool
+	t         *Transport
+	cacheKey  connectMethodKey
+	conn      net.Conn
+	tlsState  *tls.ConnectionState
+	br        *bufio.Reader       // from conn
+	bw        *bufio.Writer       // to conn
+	nwrite    int64               // bytes written
+	reqch     chan requestAndChan // written by roundTrip; read by readLoop
+	writech   chan writeRequest   // written by roundTrip; read by writeLoop
+	closech   chan struct{}       // closed when conn closed
+	isProxy   bool
+	sawEOF    bool  // whether we've seen EOF from conn; owned by readLoop
+	readLimit int64 // bytes allowed to be read; owned by readLoop
 	// writeErrCh passes the request write error (usually nil)
 	// from the writeLoop goroutine to the readLoop which passes
 	// it off to the res.Body reader, which then uses it to decide
 	// whether or not a connection can be reused. Issue 7569.
 	writeErrCh chan error
 
-	lk                   sync.Mutex // guards following fields
+	writeLoopDone chan struct{} // closed when write loop ends
+
+	// Both guarded by Transport.idleMu:
+	idleAt    time.Time   // time it last become idle
+	idleTimer *time.Timer // holding an AfterFunc to close it
+
+	mu                   sync.Mutex // guards following fields
 	numExpectedResponses int
 	closed               error // set non-nil when conn is closed, before closech is closed
 	broken               bool  // an error has happened on this connection; marked broken so it's not reused.
@@ -1011,45 +1202,153 @@ type persistConn struct {
 	mutateHeaderFunc func(Header)
 }
 
+func (pc *persistConn) maxHeaderResponseSize() int64 {
+	if v := pc.t.MaxResponseHeaderBytes; v != 0 {
+		return v
+	}
+	return 10 << 20 // conservative default; same as http2
+}
+
+func (pc *persistConn) Read(p []byte) (n int, err error) {
+	if pc.readLimit <= 0 {
+		return 0, fmt.Errorf("read limit of %d bytes exhausted", pc.maxHeaderResponseSize())
+	}
+	if int64(len(p)) > pc.readLimit {
+		p = p[:pc.readLimit]
+	}
+	n, err = pc.conn.Read(p)
+	if err == io.EOF {
+		pc.sawEOF = true
+	}
+	pc.readLimit -= int64(n)
+	return
+}
+
 // isBroken reports whether this connection is in a known broken state.
 func (pc *persistConn) isBroken() bool {
-	pc.lk.Lock()
-	b := pc.broken
-	pc.lk.Unlock()
+	pc.mu.Lock()
+	b := pc.closed != nil
+	pc.mu.Unlock()
 	return b
 }
 
 // isCanceled reports whether this connection was closed due to CancelRequest.
 func (pc *persistConn) isCanceled() bool {
-	pc.lk.Lock()
-	defer pc.lk.Unlock()
+	pc.mu.Lock()
+	defer pc.mu.Unlock()
 	return pc.canceled
 }
 
 // isReused reports whether this connection is in a known broken state.
 func (pc *persistConn) isReused() bool {
-	pc.lk.Lock()
+	pc.mu.Lock()
 	r := pc.reused
-	pc.lk.Unlock()
+	pc.mu.Unlock()
 	return r
 }
 
+func (pc *persistConn) gotIdleConnTrace(idleAt time.Time) (t httptrace.GotConnInfo) {
+	pc.mu.Lock()
+	defer pc.mu.Unlock()
+	t.Reused = pc.reused
+	t.Conn = pc.conn
+	t.WasIdle = true
+	if !idleAt.IsZero() {
+		t.IdleTime = time.Since(idleAt)
+	}
+	return
+}
+
 func (pc *persistConn) cancelRequest() {
-	pc.lk.Lock()
-	defer pc.lk.Unlock()
+	pc.mu.Lock()
+	defer pc.mu.Unlock()
 	pc.canceled = true
 	pc.closeLocked(errRequestCanceled)
 }
 
+// closeConnIfStillIdle closes the connection if it's still sitting idle.
+// This is what's called by the persistConn's idleTimer, and is run in its
+// own goroutine.
+func (pc *persistConn) closeConnIfStillIdle() {
+	t := pc.t
+	t.idleMu.Lock()
+	defer t.idleMu.Unlock()
+	if _, ok := t.idleLRU.m[pc]; !ok {
+		// Not idle.
+		return
+	}
+	t.removeIdleConnLocked(pc)
+	pc.close(errIdleConnTimeout)
+}
+
+// mapRoundTripErrorFromReadLoop maps the provided readLoop error into
+// the error value that should be returned from persistConn.roundTrip.
+//
+// The startBytesWritten value should be the value of pc.nwrite before the roundTrip
+// started writing the request.
+func (pc *persistConn) mapRoundTripErrorFromReadLoop(startBytesWritten int64, err error) (out error) {
+	if err == nil {
+		return nil
+	}
+	if pc.isCanceled() {
+		return errRequestCanceled
+	}
+	if err == errServerClosedIdle || err == errServerClosedConn {
+		return err
+	}
+	if pc.isBroken() {
+		<-pc.writeLoopDone
+		if pc.nwrite == startBytesWritten {
+			return nothingWrittenError{err}
+		}
+	}
+	return err
+}
+
+// mapRoundTripErrorAfterClosed returns the error value to be propagated
+// up to Transport.RoundTrip method when persistConn.roundTrip sees
+// its pc.closech channel close, indicating the persistConn is dead.
+// (after closech is closed, pc.closed is valid).
+func (pc *persistConn) mapRoundTripErrorAfterClosed(startBytesWritten int64) error {
+	if pc.isCanceled() {
+		return errRequestCanceled
+	}
+	err := pc.closed
+	if err == errServerClosedIdle || err == errServerClosedConn {
+		// Don't decorate
+		return err
+	}
+
+	// Wait for the writeLoop goroutine to terminated, and then
+	// see if we actually managed to write anything. If not, we
+	// can retry the request.
+	<-pc.writeLoopDone
+	if pc.nwrite == startBytesWritten {
+		return nothingWrittenError{err}
+	}
+
+	return fmt.Errorf("net/http: HTTP/1.x transport connection broken: %v", err)
+
+}
+
 func (pc *persistConn) readLoop() {
 	closeErr := errReadLoopExiting // default value, if not changed below
-	defer func() { pc.close(closeErr) }()
+	defer func() {
+		pc.close(closeErr)
+		pc.t.removeIdleConn(pc)
+	}()
 
-	tryPutIdleConn := func() bool {
+	tryPutIdleConn := func(trace *httptrace.ClientTrace) bool {
 		if err := pc.t.tryPutIdleConn(pc); err != nil {
 			closeErr = err
+			if trace != nil && trace.PutIdleConn != nil && err != errKeepAlivesDisabled {
+				trace.PutIdleConn(err)
+			}
 			return false
 		}
+		if trace != nil && trace.PutIdleConn != nil {
+			trace.PutIdleConn(nil)
+		}
 		return true
 	}
 
@@ -1066,27 +1365,33 @@ func (pc *persistConn) readLoop() {
 
 	alive := true
 	for alive {
+		pc.readLimit = pc.maxHeaderResponseSize()
 		_, err := pc.br.Peek(1)
-		if err != nil {
-			err = beforeRespHeaderError{err}
-		}
 
-		pc.lk.Lock()
+		pc.mu.Lock()
 		if pc.numExpectedResponses == 0 {
 			pc.readLoopPeekFailLocked(err)
-			pc.lk.Unlock()
+			pc.mu.Unlock()
 			return
 		}
-		pc.lk.Unlock()
+		pc.mu.Unlock()
 
 		rc := <-pc.reqch
+		trace := httptrace.ContextClientTrace(rc.req.Context())
 
 		var resp *Response
 		if err == nil {
-			resp, err = pc.readResponse(rc)
+			resp, err = pc.readResponse(rc, trace)
+		} else {
+			err = errServerClosedConn
+			closeErr = err
 		}
 
 		if err != nil {
+			if pc.readLimit <= 0 {
+				err = fmt.Errorf("net/http: server response headers exceeded %d bytes; aborted", pc.maxHeaderResponseSize())
+			}
+
 			// If we won't be able to retry this request later (from the
 			// roundTrip goroutine), mark it as done now.
 			// BEFORE the send on rc.ch, as the client might re-use the
@@ -1094,7 +1399,7 @@ func (pc *persistConn) readLoop() {
 			// t.setReqCanceler from this persistConn while the Transport
 			// potentially spins up a different persistConn for the
 			// caller's subsequent request.
-			if checkTransportResend(err, rc.req, pc) != nil {
+			if !pc.shouldRetryRequest(rc.req, err) {
 				pc.t.setReqCanceler(rc.req, nil)
 			}
 			select {
@@ -1104,10 +1409,11 @@ func (pc *persistConn) readLoop() {
 			}
 			return
 		}
+		pc.readLimit = maxInt64 // effictively no limit for response bodies
 
-		pc.lk.Lock()
+		pc.mu.Lock()
 		pc.numExpectedResponses--
-		pc.lk.Unlock()
+		pc.mu.Unlock()
 
 		hasBody := rc.req.Method != "HEAD" && resp.ContentLength != 0
 
@@ -1130,7 +1436,7 @@ func (pc *persistConn) readLoop() {
 			alive = alive &&
 				!pc.sawEOF &&
 				pc.wroteRequest() &&
-				tryPutIdleConn()
+				tryPutIdleConn(trace)
 
 			select {
 			case rc.ch <- responseAndError{res: resp}:
@@ -1145,25 +1451,33 @@ func (pc *persistConn) readLoop() {
 			continue
 		}
 
-		if rc.addedGzip {
-			maybeUngzipResponse(resp)
+		waitForBodyRead := make(chan bool, 2)
+		body := &bodyEOFSignal{
+			body: resp.Body,
+			earlyCloseFn: func() error {
+				waitForBodyRead <- false
+				return nil
+
+			},
+			fn: func(err error) error {
+				isEOF := err == io.EOF
+				waitForBodyRead <- isEOF
+				if isEOF {
+					<-eofc // see comment above eofc declaration
+				} else if err != nil && pc.isCanceled() {
+					return errRequestCanceled
+				}
+				return err
+			},
 		}
-		resp.Body = &bodyEOFSignal{body: resp.Body}
 
-		waitForBodyRead := make(chan bool, 2)
-		resp.Body.(*bodyEOFSignal).earlyCloseFn = func() error {
-			waitForBodyRead <- false
-			return nil
-		}
-		resp.Body.(*bodyEOFSignal).fn = func(err error) error {
-			isEOF := err == io.EOF
-			waitForBodyRead <- isEOF
-			if isEOF {
-				<-eofc // see comment above eofc declaration
-			} else if err != nil && pc.isCanceled() {
-				return errRequestCanceled
-			}
-			return err
+		resp.Body = body
+		if rc.addedGzip && resp.Header.Get("Content-Encoding") == "gzip" {
+			resp.Body = &gzipReader{body: body}
+			resp.Header.Del("Content-Encoding")
+			resp.Header.Del("Content-Length")
+			resp.ContentLength = -1
+			resp.Uncompressed = true
 		}
 
 		select {
@@ -1182,13 +1496,16 @@ func (pc *persistConn) readLoop() {
 				bodyEOF &&
 				!pc.sawEOF &&
 				pc.wroteRequest() &&
-				tryPutIdleConn()
+				tryPutIdleConn(trace)
 			if bodyEOF {
 				eofc <- struct{}{}
 			}
 		case <-rc.req.Cancel:
 			alive = false
 			pc.t.CancelRequest(rc.req)
+		case <-rc.req.Context().Done():
+			alive = false
+			pc.t.CancelRequest(rc.req)
 		case <-pc.closech:
 			alive = false
 		}
@@ -1197,15 +1514,6 @@ func (pc *persistConn) readLoop() {
 	}
 }
 
-func maybeUngzipResponse(resp *Response) {
-	if resp.Header.Get("Content-Encoding") == "gzip" {
-		resp.Header.Del("Content-Encoding")
-		resp.Header.Del("Content-Length")
-		resp.ContentLength = -1
-		resp.Body = &gzipReader{body: resp.Body}
-	}
-}
-
 func (pc *persistConn) readLoopPeekFailLocked(peekErr error) {
 	if pc.closed != nil {
 		return
@@ -1224,19 +1532,29 @@ func (pc *persistConn) readLoopPeekFailLocked(peekErr error) {
 
 // readResponse reads an HTTP response (or two, in the case of "Expect:
 // 100-continue") from the server. It returns the final non-100 one.
-func (pc *persistConn) readResponse(rc requestAndChan) (resp *Response, err error) {
+// trace is optional.
+func (pc *persistConn) readResponse(rc requestAndChan, trace *httptrace.ClientTrace) (resp *Response, err error) {
+	if trace != nil && trace.GotFirstResponseByte != nil {
+		if peek, err := pc.br.Peek(1); err == nil && len(peek) == 1 {
+			trace.GotFirstResponseByte()
+		}
+	}
 	resp, err = ReadResponse(pc.br, rc.req)
 	if err != nil {
 		return
 	}
 	if rc.continueCh != nil {
 		if resp.StatusCode == 100 {
+			if trace != nil && trace.Got100Continue != nil {
+				trace.Got100Continue()
+			}
 			rc.continueCh <- struct{}{}
 		} else {
 			close(rc.continueCh)
 		}
 	}
 	if resp.StatusCode == 100 {
+		pc.readLimit = pc.maxHeaderResponseSize() // reset the limit
 		resp, err = ReadResponse(pc.br, rc.req)
 		if err != nil {
 			return
@@ -1268,24 +1586,33 @@ func (pc *persistConn) waitForContinue(continueCh <-chan struct{}) func() bool {
 	}
 }
 
+// nothingWrittenError wraps a write errors which ended up writing zero bytes.
+type nothingWrittenError struct {
+	error
+}
+
 func (pc *persistConn) writeLoop() {
+	defer close(pc.writeLoopDone)
 	for {
 		select {
 		case wr := <-pc.writech:
-			if pc.isBroken() {
-				wr.ch <- errors.New("http: can't write HTTP request on broken connection")
-				continue
-			}
+			startBytesWritten := pc.nwrite
 			err := wr.req.Request.write(pc.bw, pc.isProxy, wr.req.extra, pc.waitForContinue(wr.continueCh))
 			if err == nil {
 				err = pc.bw.Flush()
 			}
 			if err != nil {
-				pc.markBroken()
 				wr.req.Request.closeBody()
+				if pc.nwrite == startBytesWritten {
+					err = nothingWrittenError{err}
+				}
 			}
 			pc.writeErrCh <- err // to the body reader, which might recycle us
 			wr.ch <- err         // to the roundTrip function
+			if err != nil {
+				pc.close(err)
+				return
+			}
 		case <-pc.closech:
 			return
 		}
@@ -1331,9 +1658,9 @@ type requestAndChan struct {
 	req *Request
 	ch  chan responseAndError // unbuffered; always send in select on callerGone
 
-	// did the Transport (as opposed to the client code) add an
-	// Accept-Encoding gzip header? only if it we set it do
-	// we transparently decode the gzip.
+	// whether the Transport (as opposed to the user client code)
+	// added the Accept-Encoding gzip header. If the Transport
+	// set it, only then do we transparently decode the gzip.
 	addedGzip bool
 
 	// Optional blocking chan for Expect: 100-continue (for send).
@@ -1353,7 +1680,7 @@ type writeRequest struct {
 	req *transportRequest
 	ch  chan<- error
 
-	// Optional blocking chan for Expect: 100-continue (for recieve).
+	// Optional blocking chan for Expect: 100-continue (for receive).
 	// If not nil, writeLoop blocks sending request body until
 	// it receives from this chan.
 	continueCh <-chan struct{}
@@ -1369,7 +1696,6 @@ func (e *httpError) Timeout() bool   { return e.timeout }
 func (e *httpError) Temporary() bool { return true }
 
 var errTimeout error = &httpError{err: "net/http: timeout awaiting response headers", timeout: true}
-var errClosed error = &httpError{err: "net/http: server closed connection before response was received"}
 var errRequestCanceled = errors.New("net/http: request canceled")
 var errRequestCanceledConn = errors.New("net/http: request canceled while waiting for connection") // TODO: unify?
 
@@ -1387,22 +1713,16 @@ var (
 	testHookReadLoopBeforeNextRead             = nop
 )
 
-// beforeRespHeaderError is used to indicate when an IO error has occurred before
-// any header data was received.
-type beforeRespHeaderError struct {
-	error
-}
-
 func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err error) {
 	testHookEnterRoundTrip()
 	if !pc.t.replaceReqCanceler(req.Request, pc.cancelRequest) {
 		pc.t.putOrCloseIdleConn(pc)
 		return nil, errRequestCanceled
 	}
-	pc.lk.Lock()
+	pc.mu.Lock()
 	pc.numExpectedResponses++
 	headerFn := pc.mutateHeaderFunc
-	pc.lk.Unlock()
+	pc.mu.Unlock()
 
 	if headerFn != nil {
 		headerFn(req.extraHeaders())
@@ -1448,6 +1768,7 @@ func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err err
 	// Write the request concurrently with waiting for a response,
 	// in case the server decides to reply before reading our full
 	// request body.
+	startBytesWritten := pc.nwrite
 	writeErrCh := make(chan error, 1)
 	pc.writech <- writeRequest{req, writeErrCh, continueCh}
 
@@ -1472,7 +1793,7 @@ WaitResponse:
 				if pc.isCanceled() {
 					err = errRequestCanceled
 				}
-				re = responseAndError{err: beforeRespHeaderError{err}}
+				re = responseAndError{err: err}
 				pc.close(fmt.Errorf("write error: %v", err))
 				break WaitResponse
 			}
@@ -1482,26 +1803,21 @@ WaitResponse:
 				respHeaderTimer = timer.C
 			}
 		case <-pc.closech:
-			var err error
-			if pc.isCanceled() {
-				err = errRequestCanceled
-			} else {
-				err = beforeRespHeaderError{fmt.Errorf("net/http: HTTP/1 transport connection broken: %v", pc.closed)}
-			}
-			re = responseAndError{err: err}
+			re = responseAndError{err: pc.mapRoundTripErrorAfterClosed(startBytesWritten)}
 			break WaitResponse
 		case <-respHeaderTimer:
 			pc.close(errTimeout)
 			re = responseAndError{err: errTimeout}
 			break WaitResponse
 		case re = <-resc:
-			if re.err != nil && pc.isCanceled() {
-				re.err = errRequestCanceled
-			}
+			re.err = pc.mapRoundTripErrorFromReadLoop(startBytesWritten, re.err)
 			break WaitResponse
 		case <-cancelChan:
 			pc.t.CancelRequest(req.Request)
 			cancelChan = nil
+		case <-req.Context().Done():
+			pc.t.CancelRequest(req.Request)
+			cancelChan = nil
 		}
 	}
 
@@ -1514,21 +1830,12 @@ WaitResponse:
 	return re.res, re.err
 }
 
-// markBroken marks a connection as broken (so it's not reused).
-// It differs from close in that it doesn't close the underlying
-// connection for use when it's still being read.
-func (pc *persistConn) markBroken() {
-	pc.lk.Lock()
-	defer pc.lk.Unlock()
-	pc.broken = true
-}
-
 // markReused marks this connection as having been successfully used for a
 // request and response.
 func (pc *persistConn) markReused() {
-	pc.lk.Lock()
+	pc.mu.Lock()
 	pc.reused = true
-	pc.lk.Unlock()
+	pc.mu.Unlock()
 }
 
 // close closes the underlying TCP connection and closes
@@ -1537,8 +1844,8 @@ func (pc *persistConn) markReused() {
 // The provided err is only for testing and debugging; in normal
 // circumstances it should never be seen by users.
 func (pc *persistConn) close(err error) {
-	pc.lk.Lock()
-	defer pc.lk.Unlock()
+	pc.mu.Lock()
+	defer pc.mu.Unlock()
 	pc.closeLocked(err)
 }
 
@@ -1554,7 +1861,7 @@ func (pc *persistConn) closeLocked(err error) {
 			// handlePendingDial's putOrCloseIdleConn when
 			// it turns out the abandoned connection in
 			// flight ended up negotiating an alternate
-			// protocol.  We don't use the connection
+			// protocol. We don't use the connection
 			// freelist for http2. That's done by the
 			// alternate protocol's RoundTripper.
 		} else {
@@ -1579,7 +1886,11 @@ func canonicalAddr(url *url.URL) string {
 	return addr
 }
 
-// bodyEOFSignal wraps a ReadCloser but runs fn (if non-nil) at most
+// bodyEOFSignal is used by the HTTP/1 transport when reading response
+// bodies to make sure we see the end of a response body before
+// proceeding and reading on the connection again.
+//
+// It wraps a ReadCloser but runs fn (if non-nil) at most
 // once, right before its final (error-producing) Read or Close call
 // returns. fn should return the new error to return from Read or Close.
 //
@@ -1595,12 +1906,14 @@ type bodyEOFSignal struct {
 	earlyCloseFn func() error      // optional alt Close func used if io.EOF not seen
 }
 
+var errReadOnClosedResBody = errors.New("http: read on closed response body")
+
 func (es *bodyEOFSignal) Read(p []byte) (n int, err error) {
 	es.mu.Lock()
 	closed, rerr := es.closed, es.rerr
 	es.mu.Unlock()
 	if closed {
-		return 0, errors.New("http: read on closed response body")
+		return 0, errReadOnClosedResBody
 	}
 	if rerr != nil {
 		return 0, rerr
@@ -1645,16 +1958,29 @@ func (es *bodyEOFSignal) condfn(err error) error {
 // gzipReader wraps a response body so it can lazily
 // call gzip.NewReader on the first call to Read
 type gzipReader struct {
-	body io.ReadCloser // underlying Response.Body
-	zr   io.Reader     // lazily-initialized gzip reader
+	body *bodyEOFSignal // underlying HTTP/1 response body framing
+	zr   *gzip.Reader   // lazily-initialized gzip reader
+	zerr error          // any error from gzip.NewReader; sticky
 }
 
 func (gz *gzipReader) Read(p []byte) (n int, err error) {
 	if gz.zr == nil {
-		gz.zr, err = gzip.NewReader(gz.body)
-		if err != nil {
-			return 0, err
+		if gz.zerr == nil {
+			gz.zr, gz.zerr = gzip.NewReader(gz.body)
 		}
+		if gz.zerr != nil {
+			return 0, gz.zerr
+		}
+	}
+
+	gz.body.mu.Lock()
+	if gz.body.closed {
+		err = errReadOnClosedResBody
+	}
+	gz.body.mu.Unlock()
+
+	if err != nil {
+		return 0, err
 	}
 	return gz.zr.Read(p)
 }
@@ -1674,19 +2000,6 @@ func (tlsHandshakeTimeoutError) Timeout() bool   { return true }
 func (tlsHandshakeTimeoutError) Temporary() bool { return true }
 func (tlsHandshakeTimeoutError) Error() string   { return "net/http: TLS handshake timeout" }
 
-type noteEOFReader struct {
-	r      io.Reader
-	sawEOF *bool
-}
-
-func (nr noteEOFReader) Read(p []byte) (n int, err error) {
-	n, err = nr.r.Read(p)
-	if err == io.EOF {
-		*nr.sawEOF = true
-	}
-	return
-}
-
 // fakeLocker is a sync.Locker which does nothing. It's used to guard
 // test-only fields when not under test, to avoid runtime atomic
 // overhead.
@@ -1695,17 +2008,6 @@ type fakeLocker struct{}
 func (fakeLocker) Lock()   {}
 func (fakeLocker) Unlock() {}
 
-func isNetWriteError(err error) bool {
-	switch e := err.(type) {
-	case *url.Error:
-		return isNetWriteError(e.Err)
-	case *net.OpError:
-		return e.Op == "write"
-	default:
-		return false
-	}
-}
-
 // cloneTLSConfig returns a shallow clone of the exported
 // fields of cfg, ignoring the unexported sync.Once, which
 // contains a mutex and must not be copied.
@@ -1722,25 +2024,27 @@ func cloneTLSConfig(cfg *tls.Config) *tls.Config {
 		return &tls.Config{}
 	}
 	return &tls.Config{
-		Rand:                     cfg.Rand,
-		Time:                     cfg.Time,
-		Certificates:             cfg.Certificates,
-		NameToCertificate:        cfg.NameToCertificate,
-		GetCertificate:           cfg.GetCertificate,
-		RootCAs:                  cfg.RootCAs,
-		NextProtos:               cfg.NextProtos,
-		ServerName:               cfg.ServerName,
-		ClientAuth:               cfg.ClientAuth,
-		ClientCAs:                cfg.ClientCAs,
-		InsecureSkipVerify:       cfg.InsecureSkipVerify,
-		CipherSuites:             cfg.CipherSuites,
-		PreferServerCipherSuites: cfg.PreferServerCipherSuites,
-		SessionTicketsDisabled:   cfg.SessionTicketsDisabled,
-		SessionTicketKey:         cfg.SessionTicketKey,
-		ClientSessionCache:       cfg.ClientSessionCache,
-		MinVersion:               cfg.MinVersion,
-		MaxVersion:               cfg.MaxVersion,
-		CurvePreferences:         cfg.CurvePreferences,
+		Rand:                        cfg.Rand,
+		Time:                        cfg.Time,
+		Certificates:                cfg.Certificates,
+		NameToCertificate:           cfg.NameToCertificate,
+		GetCertificate:              cfg.GetCertificate,
+		RootCAs:                     cfg.RootCAs,
+		NextProtos:                  cfg.NextProtos,
+		ServerName:                  cfg.ServerName,
+		ClientAuth:                  cfg.ClientAuth,
+		ClientCAs:                   cfg.ClientCAs,
+		InsecureSkipVerify:          cfg.InsecureSkipVerify,
+		CipherSuites:                cfg.CipherSuites,
+		PreferServerCipherSuites:    cfg.PreferServerCipherSuites,
+		SessionTicketsDisabled:      cfg.SessionTicketsDisabled,
+		SessionTicketKey:            cfg.SessionTicketKey,
+		ClientSessionCache:          cfg.ClientSessionCache,
+		MinVersion:                  cfg.MinVersion,
+		MaxVersion:                  cfg.MaxVersion,
+		CurvePreferences:            cfg.CurvePreferences,
+		DynamicRecordSizingDisabled: cfg.DynamicRecordSizingDisabled,
+		Renegotiation:               cfg.Renegotiation,
 	}
 }
 
@@ -1753,22 +2057,63 @@ func cloneTLSClientConfig(cfg *tls.Config) *tls.Config {
 		return &tls.Config{}
 	}
 	return &tls.Config{
-		Rand:                     cfg.Rand,
-		Time:                     cfg.Time,
-		Certificates:             cfg.Certificates,
-		NameToCertificate:        cfg.NameToCertificate,
-		GetCertificate:           cfg.GetCertificate,
-		RootCAs:                  cfg.RootCAs,
-		NextProtos:               cfg.NextProtos,
-		ServerName:               cfg.ServerName,
-		ClientAuth:               cfg.ClientAuth,
-		ClientCAs:                cfg.ClientCAs,
-		InsecureSkipVerify:       cfg.InsecureSkipVerify,
-		CipherSuites:             cfg.CipherSuites,
-		PreferServerCipherSuites: cfg.PreferServerCipherSuites,
-		ClientSessionCache:       cfg.ClientSessionCache,
-		MinVersion:               cfg.MinVersion,
-		MaxVersion:               cfg.MaxVersion,
-		CurvePreferences:         cfg.CurvePreferences,
+		Rand:                        cfg.Rand,
+		Time:                        cfg.Time,
+		Certificates:                cfg.Certificates,
+		NameToCertificate:           cfg.NameToCertificate,
+		GetCertificate:              cfg.GetCertificate,
+		RootCAs:                     cfg.RootCAs,
+		NextProtos:                  cfg.NextProtos,
+		ServerName:                  cfg.ServerName,
+		ClientAuth:                  cfg.ClientAuth,
+		ClientCAs:                   cfg.ClientCAs,
+		InsecureSkipVerify:          cfg.InsecureSkipVerify,
+		CipherSuites:                cfg.CipherSuites,
+		PreferServerCipherSuites:    cfg.PreferServerCipherSuites,
+		ClientSessionCache:          cfg.ClientSessionCache,
+		MinVersion:                  cfg.MinVersion,
+		MaxVersion:                  cfg.MaxVersion,
+		CurvePreferences:            cfg.CurvePreferences,
+		DynamicRecordSizingDisabled: cfg.DynamicRecordSizingDisabled,
+		Renegotiation:               cfg.Renegotiation,
 	}
 }
+
+type connLRU struct {
+	ll *list.List // list.Element.Value type is of *persistConn
+	m  map[*persistConn]*list.Element
+}
+
+// add adds pc to the head of the linked list.
+func (cl *connLRU) add(pc *persistConn) {
+	if cl.ll == nil {
+		cl.ll = list.New()
+		cl.m = make(map[*persistConn]*list.Element)
+	}
+	ele := cl.ll.PushFront(pc)
+	if _, ok := cl.m[pc]; ok {
+		panic("persistConn was already in LRU")
+	}
+	cl.m[pc] = ele
+}
+
+func (cl *connLRU) removeOldest() *persistConn {
+	ele := cl.ll.Back()
+	pc := ele.Value.(*persistConn)
+	cl.ll.Remove(ele)
+	delete(cl.m, pc)
+	return pc
+}
+
+// remove removes pc from cl.
+func (cl *connLRU) remove(pc *persistConn) {
+	if ele, ok := cl.m[pc]; ok {
+		cl.ll.Remove(ele)
+		delete(cl.m, pc)
+	}
+}
+
+// len returns the number of items in the cache.
+func (cl *connLRU) len() int {
+	return len(cl.m)
+}
diff --git a/libgo/go/net/http/transport_internal_test.go b/libgo/go/net/http/transport_internal_test.go
new file mode 100644
index 00000000000..a157d906300
--- /dev/null
+++ b/libgo/go/net/http/transport_internal_test.go
@@ -0,0 +1,69 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// White-box tests for transport.go (in package http instead of http_test).
+
+package http
+
+import (
+	"errors"
+	"net"
+	"testing"
+)
+
+// Issue 15446: incorrect wrapping of errors when server closes an idle connection.
+func TestTransportPersistConnReadLoopEOF(t *testing.T) {
+	ln := newLocalListener(t)
+	defer ln.Close()
+
+	connc := make(chan net.Conn, 1)
+	go func() {
+		defer close(connc)
+		c, err := ln.Accept()
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		connc <- c
+	}()
+
+	tr := new(Transport)
+	req, _ := NewRequest("GET", "http://"+ln.Addr().String(), nil)
+	treq := &transportRequest{Request: req}
+	cm := connectMethod{targetScheme: "http", targetAddr: ln.Addr().String()}
+	pc, err := tr.getConn(treq, cm)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer pc.close(errors.New("test over"))
+
+	conn := <-connc
+	if conn == nil {
+		// Already called t.Error in the accept goroutine.
+		return
+	}
+	conn.Close() // simulate the server hanging up on the client
+
+	_, err = pc.roundTrip(treq)
+	if err != errServerClosedConn && err != errServerClosedIdle {
+		t.Fatalf("roundTrip = %#v, %v; want errServerClosedConn or errServerClosedIdle", err, err)
+	}
+
+	<-pc.closech
+	err = pc.closed
+	if err != errServerClosedConn && err != errServerClosedIdle {
+		t.Fatalf("pc.closed = %#v, %v; want errServerClosedConn or errServerClosedIdle", err, err)
+	}
+}
+
+func newLocalListener(t *testing.T) net.Listener {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		ln, err = net.Listen("tcp6", "[::1]:0")
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return ln
+}
diff --git a/libgo/go/net/http/transport_test.go b/libgo/go/net/http/transport_test.go
index 0c901b30a44..72b98f16d7e 100644
--- a/libgo/go/net/http/transport_test.go
+++ b/libgo/go/net/http/transport_test.go
@@ -13,16 +13,20 @@ import (
 	"bufio"
 	"bytes"
 	"compress/gzip"
+	"context"
 	"crypto/rand"
 	"crypto/tls"
 	"errors"
 	"fmt"
+	"internal/nettrace"
+	"internal/testenv"
 	"io"
 	"io/ioutil"
 	"log"
 	"net"
 	. "net/http"
 	"net/http/httptest"
+	"net/http/httptrace"
 	"net/http/httputil"
 	"net/http/internal"
 	"net/url"
@@ -379,8 +383,8 @@ func TestTransportMaxPerHostIdleConns(t *testing.T) {
 		}
 	}))
 	defer ts.Close()
-	maxIdleConns := 2
-	tr := &Transport{DisableKeepAlives: false, MaxIdleConnsPerHost: maxIdleConns}
+	maxIdleConnsPerHost := 2
+	tr := &Transport{DisableKeepAlives: false, MaxIdleConnsPerHost: maxIdleConnsPerHost}
 	c := &Client{Transport: tr}
 
 	// Start 3 outstanding requests and wait for the server to get them.
@@ -425,14 +429,65 @@ func TestTransportMaxPerHostIdleConns(t *testing.T) {
 
 	resch <- "res2"
 	<-donech
-	if e, g := 2, tr.IdleConnCountForTesting(cacheKey); e != g {
-		t.Errorf("after second response, expected %d idle conns; got %d", e, g)
+	if g, w := tr.IdleConnCountForTesting(cacheKey), 2; g != w {
+		t.Errorf("after second response, idle conns = %d; want %d", g, w)
 	}
 
 	resch <- "res3"
 	<-donech
-	if e, g := maxIdleConns, tr.IdleConnCountForTesting(cacheKey); e != g {
-		t.Errorf("after third response, still expected %d idle conns; got %d", e, g)
+	if g, w := tr.IdleConnCountForTesting(cacheKey), maxIdleConnsPerHost; g != w {
+		t.Errorf("after third response, idle conns = %d; want %d", g, w)
+	}
+}
+
+func TestTransportRemovesDeadIdleConnections(t *testing.T) {
+	if runtime.GOOS == "plan9" {
+		t.Skip("skipping test; see https://golang.org/issue/15464")
+	}
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		io.WriteString(w, r.RemoteAddr)
+	}))
+	defer ts.Close()
+
+	tr := &Transport{}
+	defer tr.CloseIdleConnections()
+	c := &Client{Transport: tr}
+
+	doReq := func(name string) string {
+		// Do a POST instead of a GET to prevent the Transport's
+		// idempotent request retry logic from kicking in...
+		res, err := c.Post(ts.URL, "", nil)
+		if err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+		if res.StatusCode != 200 {
+			t.Fatalf("%s: %v", name, res.Status)
+		}
+		defer res.Body.Close()
+		slurp, err := ioutil.ReadAll(res.Body)
+		if err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+		return string(slurp)
+	}
+
+	first := doReq("first")
+	keys1 := tr.IdleConnKeysForTesting()
+
+	ts.CloseClientConnections()
+
+	var keys2 []string
+	if !waitCondition(3*time.Second, 50*time.Millisecond, func() bool {
+		keys2 = tr.IdleConnKeysForTesting()
+		return len(keys2) == 0
+	}) {
+		t.Fatalf("Transport didn't notice idle connection's death.\nbefore: %q\n after: %q\n", keys1, keys2)
+	}
+
+	second := doReq("second")
+	if first == second {
+		t.Errorf("expected a different connection between requests. got %q both times", first)
 	}
 }
 
@@ -478,7 +533,7 @@ func TestTransportServerClosingUnexpectedly(t *testing.T) {
 
 	// This test has an expected race. Sleeping for 25 ms prevents
 	// it on most fast machines, causing the next fetch() call to
-	// succeed quickly.  But if we do get errors, fetch() will retry 5
+	// succeed quickly. But if we do get errors, fetch() will retry 5
 	// times with some delays between.
 	time.Sleep(25 * time.Millisecond)
 
@@ -518,7 +573,7 @@ func TestStressSurpriseServerCloses(t *testing.T) {
 	// after each request completes, regardless of whether it failed.
 	// If these are too high, OS X exhausts its ephemeral ports
 	// and hangs waiting for them to transition TCP states. That's
-	// not what we want to test.  TODO(bradfitz): use an io.Pipe
+	// not what we want to test. TODO(bradfitz): use an io.Pipe
 	// dialer for this test instead?
 	const (
 		numClients    = 20
@@ -853,7 +908,7 @@ func TestTransportExpect100Continue(t *testing.T) {
 		{path: "/100", body: []byte("hello"), sent: 5, status: 200},       // Got 100 followed by 200, entire body is sent.
 		{path: "/200", body: []byte("hello"), sent: 0, status: 200},       // Got 200 without 100. body isn't sent.
 		{path: "/500", body: []byte("hello"), sent: 0, status: 500},       // Got 500 without 100. body isn't sent.
-		{path: "/keepalive", body: []byte("hello"), sent: 0, status: 500}, // Althogh without Connection:close, body isn't sent.
+		{path: "/keepalive", body: []byte("hello"), sent: 0, status: 500}, // Although without Connection:close, body isn't sent.
 		{path: "/timeout", body: []byte("hello"), sent: 5, status: 200},   // Timeout exceeded and entire body is sent.
 	}
 
@@ -923,7 +978,9 @@ func TestTransportGzipRecursive(t *testing.T) {
 	}))
 	defer ts.Close()
 
-	c := &Client{Transport: &Transport{}}
+	tr := &Transport{}
+	defer tr.CloseIdleConnections()
+	c := &Client{Transport: tr}
 	res, err := c.Get(ts.URL)
 	if err != nil {
 		t.Fatal(err)
@@ -968,6 +1025,17 @@ func TestTransportGzipShort(t *testing.T) {
 	}
 }
 
+// Wait until number of goroutines is no greater than nmax, or time out.
+func waitNumGoroutine(nmax int) int {
+	nfinal := runtime.NumGoroutine()
+	for ntries := 10; ntries > 0 && nfinal > nmax; ntries-- {
+		time.Sleep(50 * time.Millisecond)
+		runtime.GC()
+		nfinal = runtime.NumGoroutine()
+	}
+	return nfinal
+}
+
 // tests that persistent goroutine connections shut down when no longer desired.
 func TestTransportPersistConnLeak(t *testing.T) {
 	setParallel(t)
@@ -1019,14 +1087,11 @@ func TestTransportPersistConnLeak(t *testing.T) {
 	}
 
 	tr.CloseIdleConnections()
-	time.Sleep(100 * time.Millisecond)
-	runtime.GC()
-	runtime.GC() // even more.
-	nfinal := runtime.NumGoroutine()
+	nfinal := waitNumGoroutine(n0 + 5)
 
 	growth := nfinal - n0
 
-	// We expect 0 or 1 extra goroutine, empirically.  Allow up to 5.
+	// We expect 0 or 1 extra goroutine, empirically. Allow up to 5.
 	// Previously we were leaking one per numReq.
 	if int(growth) > 5 {
 		t.Logf("goroutine growth: %d -> %d -> %d (delta: %d)", n0, nhigh, nfinal, growth)
@@ -1061,13 +1126,11 @@ func TestTransportPersistConnLeakShortBody(t *testing.T) {
 	}
 	nhigh := runtime.NumGoroutine()
 	tr.CloseIdleConnections()
-	time.Sleep(400 * time.Millisecond)
-	runtime.GC()
-	nfinal := runtime.NumGoroutine()
+	nfinal := waitNumGoroutine(n0 + 5)
 
 	growth := nfinal - n0
 
-	// We expect 0 or 1 extra goroutine, empirically.  Allow up to 5.
+	// We expect 0 or 1 extra goroutine, empirically. Allow up to 5.
 	// Previously we were leaking one per numReq.
 	t.Logf("goroutine growth: %d -> %d -> %d (delta: %d)", n0, nhigh, nfinal, growth)
 	if int(growth) > 5 {
@@ -1103,8 +1166,8 @@ func TestTransportIdleConnCrash(t *testing.T) {
 }
 
 // Test that the transport doesn't close the TCP connection early,
-// before the response body has been read.  This was a regression
-// which sadly lacked a triggering test.  The large response body made
+// before the response body has been read. This was a regression
+// which sadly lacked a triggering test. The large response body made
 // the old race easier to trigger.
 func TestIssue3644(t *testing.T) {
 	defer afterTest(t)
@@ -1199,7 +1262,7 @@ func TestTransportConcurrency(t *testing.T) {
 
 	// Due to the Transport's "socket late binding" (see
 	// idleConnCh in transport.go), the numReqs HTTP requests
-	// below can finish with a dial still outstanding.  To keep
+	// below can finish with a dial still outstanding. To keep
 	// the leak checker happy, keep track of pending dials and
 	// wait for them to finish (and be closed or returned to the
 	// idle pool) before we close idle connections.
@@ -1617,7 +1680,13 @@ func TestCancelRequestWithChannel(t *testing.T) {
 	}
 }
 
-func TestCancelRequestWithChannelBeforeDo(t *testing.T) {
+func TestCancelRequestWithChannelBeforeDo_Cancel(t *testing.T) {
+	testCancelRequestWithChannelBeforeDo(t, false)
+}
+func TestCancelRequestWithChannelBeforeDo_Context(t *testing.T) {
+	testCancelRequestWithChannelBeforeDo(t, true)
+}
+func testCancelRequestWithChannelBeforeDo(t *testing.T, withCtx bool) {
 	setParallel(t)
 	defer afterTest(t)
 	unblockc := make(chan bool)
@@ -1638,9 +1707,15 @@ func TestCancelRequestWithChannelBeforeDo(t *testing.T) {
 	c := &Client{Transport: tr}
 
 	req, _ := NewRequest("GET", ts.URL, nil)
-	ch := make(chan struct{})
-	req.Cancel = ch
-	close(ch)
+	if withCtx {
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+		req = req.WithContext(ctx)
+	} else {
+		ch := make(chan struct{})
+		req.Cancel = ch
+		close(ch)
+	}
 
 	_, err := c.Do(req)
 	if err == nil || !strings.Contains(err.Error(), "canceled") {
@@ -1985,7 +2060,8 @@ type proxyFromEnvTest struct {
 
 	env      string // HTTP_PROXY
 	httpsenv string // HTTPS_PROXY
-	noenv    string // NO_RPXY
+	noenv    string // NO_PROXY
+	reqmeth  string // REQUEST_METHOD
 
 	want    string
 	wanterr error
@@ -2009,6 +2085,10 @@ func (t proxyFromEnvTest) String() string {
 		space()
 		fmt.Fprintf(&buf, "no_proxy=%q", t.noenv)
 	}
+	if t.reqmeth != "" {
+		space()
+		fmt.Fprintf(&buf, "request_method=%q", t.reqmeth)
+	}
 	req := "http://example.com"
 	if t.req != "" {
 		req = t.req
@@ -2032,6 +2112,12 @@ var proxyFromEnvTests = []proxyFromEnvTest{
 	{req: "https://secure.tld/", env: "http.proxy.tld", httpsenv: "secure.proxy.tld", want: "http://secure.proxy.tld"},
 	{req: "https://secure.tld/", env: "http.proxy.tld", httpsenv: "https://secure.proxy.tld", want: "https://secure.proxy.tld"},
 
+	// Issue 16405: don't use HTTP_PROXY in a CGI environment,
+	// where HTTP_PROXY can be attacker-controlled.
+	{env: "http://10.1.2.3:8080", reqmeth: "POST",
+		want:    "<nil>",
+		wanterr: errors.New("net/http: refusing to use HTTP_PROXY value in CGI environment; see golang.org/s/cgihttpproxy")},
+
 	{want: "<nil>"},
 
 	{noenv: "example.com", req: "http://example.com/", env: "proxy", want: "<nil>"},
@@ -2047,6 +2133,7 @@ func TestProxyFromEnvironment(t *testing.T) {
 		os.Setenv("HTTP_PROXY", tt.env)
 		os.Setenv("HTTPS_PROXY", tt.httpsenv)
 		os.Setenv("NO_PROXY", tt.noenv)
+		os.Setenv("REQUEST_METHOD", tt.reqmeth)
 		ResetCachedEnvironment()
 		reqURL := tt.req
 		if reqURL == "" {
@@ -2208,7 +2295,7 @@ func TestTransportTLSHandshakeTimeout(t *testing.T) {
 // Trying to repro golang.org/issue/3514
 func TestTLSServerClosesConnection(t *testing.T) {
 	defer afterTest(t)
-	setFlaky(t, 7634)
+	testenv.SkipFlaky(t, 7634)
 
 	closedc := make(chan bool, 1)
 	ts := httptest.NewTLSServer(HandlerFunc(func(w ResponseWriter, r *Request) {
@@ -2273,7 +2360,7 @@ func TestTLSServerClosesConnection(t *testing.T) {
 }
 
 // byteFromChanReader is an io.Reader that reads a single byte at a
-// time from the channel.  When the channel is closed, the reader
+// time from the channel. When the channel is closed, the reader
 // returns io.EOF.
 type byteFromChanReader chan byte
 
@@ -2405,7 +2492,7 @@ func (plan9SleepReader) Read(p []byte) (int, error) {
 		// After the fix to unblock TCP Reads in
 		// https://golang.org/cl/15941, this sleep is required
 		// on plan9 to make sure TCP Writes before an
-		// immediate TCP close go out on the wire.  On Plan 9,
+		// immediate TCP close go out on the wire. On Plan 9,
 		// it seems that a hangup of a TCP connection with
 		// queued data doesn't send the queued data first.
 		// https://golang.org/issue/9554
@@ -2424,7 +2511,7 @@ func (f closerFunc) Close() error { return f() }
 // from (or finish writing to) the socket.
 //
 // NOTE: we resend a request only if the request is idempotent, we reused a
-// keep-alive connection, and we haven't yet received any header data.  This
+// keep-alive connection, and we haven't yet received any header data. This
 // automatically prevents an infinite resend loop because we'll run out of the
 // cached keep-alive connections eventually.
 func TestRetryIdempotentRequestsOnError(t *testing.T) {
@@ -2888,6 +2975,11 @@ func TestTransportAutomaticHTTP2(t *testing.T) {
 	testTransportAutoHTTP(t, &Transport{}, true)
 }
 
+// golang.org/issue/14391: also check DefaultTransport
+func TestTransportAutomaticHTTP2_DefaultTransport(t *testing.T) {
+	testTransportAutoHTTP(t, DefaultTransport.(*Transport), true)
+}
+
 func TestTransportAutomaticHTTP2_TLSNextProto(t *testing.T) {
 	testTransportAutoHTTP(t, &Transport{
 		TLSNextProto: make(map[string]func(string, *tls.Conn) RoundTripper),
@@ -2903,6 +2995,21 @@ func TestTransportAutomaticHTTP2_TLSConfig(t *testing.T) {
 func TestTransportAutomaticHTTP2_ExpectContinueTimeout(t *testing.T) {
 	testTransportAutoHTTP(t, &Transport{
 		ExpectContinueTimeout: 1 * time.Second,
+	}, true)
+}
+
+func TestTransportAutomaticHTTP2_Dial(t *testing.T) {
+	var d net.Dialer
+	testTransportAutoHTTP(t, &Transport{
+		Dial: d.Dial,
+	}, false)
+}
+
+func TestTransportAutomaticHTTP2_DialTLS(t *testing.T) {
+	testTransportAutoHTTP(t, &Transport{
+		DialTLS: func(network, addr string) (net.Conn, error) {
+			panic("unused")
+		},
 	}, false)
 }
 
@@ -3033,6 +3140,377 @@ func TestNoCrashReturningTransportAltConn(t *testing.T) {
 	<-handledPendingDial
 }
 
+func TestTransportReuseConnection_Gzip_Chunked(t *testing.T) {
+	testTransportReuseConnection_Gzip(t, true)
+}
+
+func TestTransportReuseConnection_Gzip_ContentLength(t *testing.T) {
+	testTransportReuseConnection_Gzip(t, false)
+}
+
+// Make sure we re-use underlying TCP connection for gzipped responses too.
+func testTransportReuseConnection_Gzip(t *testing.T, chunked bool) {
+	defer afterTest(t)
+	addr := make(chan string, 2)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		addr <- r.RemoteAddr
+		w.Header().Set("Content-Encoding", "gzip")
+		if chunked {
+			w.(Flusher).Flush()
+		}
+		w.Write(rgz) // arbitrary gzip response
+	}))
+	defer ts.Close()
+
+	tr := &Transport{}
+	defer tr.CloseIdleConnections()
+	c := &Client{Transport: tr}
+	for i := 0; i < 2; i++ {
+		res, err := c.Get(ts.URL)
+		if err != nil {
+			t.Fatal(err)
+		}
+		buf := make([]byte, len(rgz))
+		if n, err := io.ReadFull(res.Body, buf); err != nil {
+			t.Errorf("%d. ReadFull = %v, %v", i, n, err)
+		}
+		// Note: no res.Body.Close call. It should work without it,
+		// since the flate.Reader's internal buffering will hit EOF
+		// and that should be sufficient.
+	}
+	a1, a2 := <-addr, <-addr
+	if a1 != a2 {
+		t.Fatalf("didn't reuse connection")
+	}
+}
+
+func TestTransportResponseHeaderLength(t *testing.T) {
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		if r.URL.Path == "/long" {
+			w.Header().Set("Long", strings.Repeat("a", 1<<20))
+		}
+	}))
+	defer ts.Close()
+
+	tr := &Transport{
+		MaxResponseHeaderBytes: 512 << 10,
+	}
+	defer tr.CloseIdleConnections()
+	c := &Client{Transport: tr}
+	if res, err := c.Get(ts.URL); err != nil {
+		t.Fatal(err)
+	} else {
+		res.Body.Close()
+	}
+
+	res, err := c.Get(ts.URL + "/long")
+	if err == nil {
+		defer res.Body.Close()
+		var n int64
+		for k, vv := range res.Header {
+			for _, v := range vv {
+				n += int64(len(k)) + int64(len(v))
+			}
+		}
+		t.Fatalf("Unexpected success. Got %v and %d bytes of response headers", res.Status, n)
+	}
+	if want := "server response headers exceeded 524288 bytes"; !strings.Contains(err.Error(), want) {
+		t.Errorf("got error: %v; want %q", err, want)
+	}
+}
+
+func TestTransportEventTrace(t *testing.T)    { testTransportEventTrace(t, h1Mode, false) }
+func TestTransportEventTrace_h2(t *testing.T) { testTransportEventTrace(t, h2Mode, false) }
+
+// test a non-nil httptrace.ClientTrace but with all hooks set to zero.
+func TestTransportEventTrace_NoHooks(t *testing.T)    { testTransportEventTrace(t, h1Mode, true) }
+func TestTransportEventTrace_NoHooks_h2(t *testing.T) { testTransportEventTrace(t, h2Mode, true) }
+
+func testTransportEventTrace(t *testing.T, h2 bool, noHooks bool) {
+	defer afterTest(t)
+	const resBody = "some body"
+	gotWroteReqEvent := make(chan struct{})
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		if _, err := ioutil.ReadAll(r.Body); err != nil {
+			t.Error(err)
+		}
+		if !noHooks {
+			select {
+			case <-gotWroteReqEvent:
+			case <-time.After(5 * time.Second):
+				t.Error("timeout waiting for WroteRequest event")
+			}
+		}
+		io.WriteString(w, resBody)
+	}))
+	defer cst.close()
+
+	cst.tr.ExpectContinueTimeout = 1 * time.Second
+
+	var mu sync.Mutex
+	var buf bytes.Buffer
+	logf := func(format string, args ...interface{}) {
+		mu.Lock()
+		defer mu.Unlock()
+		fmt.Fprintf(&buf, format, args...)
+		buf.WriteByte('\n')
+	}
+
+	addrStr := cst.ts.Listener.Addr().String()
+	ip, port, err := net.SplitHostPort(addrStr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Install a fake DNS server.
+	ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, host string) ([]net.IPAddr, error) {
+		if host != "dns-is-faked.golang" {
+			t.Errorf("unexpected DNS host lookup for %q", host)
+			return nil, nil
+		}
+		return []net.IPAddr{{IP: net.ParseIP(ip)}}, nil
+	})
+
+	req, _ := NewRequest("POST", cst.scheme()+"://dns-is-faked.golang:"+port, strings.NewReader("some body"))
+	trace := &httptrace.ClientTrace{
+		GetConn:              func(hostPort string) { logf("Getting conn for %v ...", hostPort) },
+		GotConn:              func(ci httptrace.GotConnInfo) { logf("got conn: %+v", ci) },
+		GotFirstResponseByte: func() { logf("first response byte") },
+		PutIdleConn:          func(err error) { logf("PutIdleConn = %v", err) },
+		DNSStart:             func(e httptrace.DNSStartInfo) { logf("DNS start: %+v", e) },
+		DNSDone:              func(e httptrace.DNSDoneInfo) { logf("DNS done: %+v", e) },
+		ConnectStart:         func(network, addr string) { logf("ConnectStart: Connecting to %s %s ...", network, addr) },
+		ConnectDone: func(network, addr string, err error) {
+			if err != nil {
+				t.Errorf("ConnectDone: %v", err)
+			}
+			logf("ConnectDone: connected to %s %s = %v", network, addr, err)
+		},
+		Wait100Continue: func() { logf("Wait100Continue") },
+		Got100Continue:  func() { logf("Got100Continue") },
+		WroteRequest: func(e httptrace.WroteRequestInfo) {
+			close(gotWroteReqEvent)
+			logf("WroteRequest: %+v", e)
+		},
+	}
+	if noHooks {
+		// zero out all func pointers, trying to get some path to crash
+		*trace = httptrace.ClientTrace{}
+	}
+	req = req.WithContext(httptrace.WithClientTrace(ctx, trace))
+
+	req.Header.Set("Expect", "100-continue")
+	res, err := cst.c.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	logf("got roundtrip.response")
+	slurp, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	logf("consumed body")
+	if string(slurp) != resBody || res.StatusCode != 200 {
+		t.Fatalf("Got %q, %v; want %q, 200 OK", slurp, res.Status, resBody)
+	}
+	res.Body.Close()
+
+	if noHooks {
+		// Done at this point. Just testing a full HTTP
+		// requests can happen with a trace pointing to a zero
+		// ClientTrace, full of nil func pointers.
+		return
+	}
+
+	got := buf.String()
+	wantOnce := func(sub string) {
+		if strings.Count(got, sub) != 1 {
+			t.Errorf("expected substring %q exactly once in output.", sub)
+		}
+	}
+	wantOnceOrMore := func(sub string) {
+		if strings.Count(got, sub) == 0 {
+			t.Errorf("expected substring %q at least once in output.", sub)
+		}
+	}
+	wantOnce("Getting conn for dns-is-faked.golang:" + port)
+	wantOnce("DNS start: {Host:dns-is-faked.golang}")
+	wantOnce("DNS done: {Addrs:[{IP:" + ip + " Zone:}] Err:<nil> Coalesced:false}")
+	wantOnce("got conn: {")
+	wantOnceOrMore("Connecting to tcp " + addrStr)
+	wantOnceOrMore("connected to tcp " + addrStr + " = <nil>")
+	wantOnce("Reused:false WasIdle:false IdleTime:0s")
+	wantOnce("first response byte")
+	if !h2 {
+		wantOnce("PutIdleConn = <nil>")
+	}
+	wantOnce("Wait100Continue")
+	wantOnce("Got100Continue")
+	wantOnce("WroteRequest: {Err:<nil>}")
+	if strings.Contains(got, " to udp ") {
+		t.Errorf("should not see UDP (DNS) connections")
+	}
+	if t.Failed() {
+		t.Errorf("Output:\n%s", got)
+	}
+}
+
+func TestTransportEventTraceRealDNS(t *testing.T) {
+	defer afterTest(t)
+	tr := &Transport{}
+	defer tr.CloseIdleConnections()
+	c := &Client{Transport: tr}
+
+	var mu sync.Mutex
+	var buf bytes.Buffer
+	logf := func(format string, args ...interface{}) {
+		mu.Lock()
+		defer mu.Unlock()
+		fmt.Fprintf(&buf, format, args...)
+		buf.WriteByte('\n')
+	}
+
+	req, _ := NewRequest("GET", "http://dns-should-not-resolve.golang:80", nil)
+	trace := &httptrace.ClientTrace{
+		DNSStart:     func(e httptrace.DNSStartInfo) { logf("DNSStart: %+v", e) },
+		DNSDone:      func(e httptrace.DNSDoneInfo) { logf("DNSDone: %+v", e) },
+		ConnectStart: func(network, addr string) { logf("ConnectStart: %s %s", network, addr) },
+		ConnectDone:  func(network, addr string, err error) { logf("ConnectDone: %s %s %v", network, addr, err) },
+	}
+	req = req.WithContext(httptrace.WithClientTrace(context.Background(), trace))
+
+	resp, err := c.Do(req)
+	if err == nil {
+		resp.Body.Close()
+		t.Fatal("expected error during DNS lookup")
+	}
+
+	got := buf.String()
+	wantSub := func(sub string) {
+		if !strings.Contains(got, sub) {
+			t.Errorf("expected substring %q in output.", sub)
+		}
+	}
+	wantSub("DNSStart: {Host:dns-should-not-resolve.golang}")
+	wantSub("DNSDone: {Addrs:[] Err:")
+	if strings.Contains(got, "ConnectStart") || strings.Contains(got, "ConnectDone") {
+		t.Errorf("should not see Connect events")
+	}
+	if t.Failed() {
+		t.Errorf("Output:\n%s", got)
+	}
+}
+
+func TestTransportMaxIdleConns(t *testing.T) {
+	defer afterTest(t)
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		// No body for convenience.
+	}))
+	defer ts.Close()
+	tr := &Transport{
+		MaxIdleConns: 4,
+	}
+	defer tr.CloseIdleConnections()
+
+	ip, port, err := net.SplitHostPort(ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	c := &Client{Transport: tr}
+	ctx := context.WithValue(context.Background(), nettrace.LookupIPAltResolverKey{}, func(ctx context.Context, host string) ([]net.IPAddr, error) {
+		return []net.IPAddr{{IP: net.ParseIP(ip)}}, nil
+	})
+
+	hitHost := func(n int) {
+		req, _ := NewRequest("GET", fmt.Sprintf("http://host-%d.dns-is-faked.golang:"+port, n), nil)
+		req = req.WithContext(ctx)
+		res, err := c.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		res.Body.Close()
+	}
+	for i := 0; i < 4; i++ {
+		hitHost(i)
+	}
+	want := []string{
+		"|http|host-0.dns-is-faked.golang:" + port,
+		"|http|host-1.dns-is-faked.golang:" + port,
+		"|http|host-2.dns-is-faked.golang:" + port,
+		"|http|host-3.dns-is-faked.golang:" + port,
+	}
+	if got := tr.IdleConnKeysForTesting(); !reflect.DeepEqual(got, want) {
+		t.Fatalf("idle conn keys mismatch.\n got: %q\nwant: %q\n", got, want)
+	}
+
+	// Now hitting the 5th host should kick out the first host:
+	hitHost(4)
+	want = []string{
+		"|http|host-1.dns-is-faked.golang:" + port,
+		"|http|host-2.dns-is-faked.golang:" + port,
+		"|http|host-3.dns-is-faked.golang:" + port,
+		"|http|host-4.dns-is-faked.golang:" + port,
+	}
+	if got := tr.IdleConnKeysForTesting(); !reflect.DeepEqual(got, want) {
+		t.Fatalf("idle conn keys mismatch after 5th host.\n got: %q\nwant: %q\n", got, want)
+	}
+}
+
+func TestTransportIdleConnTimeout(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+	defer afterTest(t)
+
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		// No body for convenience.
+	}))
+	defer ts.Close()
+
+	const timeout = 1 * time.Second
+	tr := &Transport{
+		IdleConnTimeout: timeout,
+	}
+	defer tr.CloseIdleConnections()
+	c := &Client{Transport: tr}
+
+	var conn string
+	doReq := func(n int) {
+		req, _ := NewRequest("GET", ts.URL, nil)
+		req = req.WithContext(httptrace.WithClientTrace(context.Background(), &httptrace.ClientTrace{
+			PutIdleConn: func(err error) {
+				if err != nil {
+					t.Errorf("failed to keep idle conn: %v", err)
+				}
+			},
+		}))
+		res, err := c.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		res.Body.Close()
+		conns := tr.IdleConnStrsForTesting()
+		if len(conns) != 1 {
+			t.Fatalf("req %v: unexpected number of idle conns: %q", n, conns)
+		}
+		if conn == "" {
+			conn = conns[0]
+		}
+		if conn != conns[0] {
+			t.Fatalf("req %v: cached connection changed; expected the same one throughout the test", n)
+		}
+	}
+	for i := 0; i < 3; i++ {
+		doReq(i)
+		time.Sleep(timeout / 2)
+	}
+	time.Sleep(timeout * 3 / 2)
+	if got := tr.IdleConnStrsForTesting(); len(got) != 0 {
+		t.Errorf("idle conns = %q; want none", got)
+	}
+}
+
 var errFakeRoundTrip = errors.New("fake roundtrip")
 
 type funcRoundTripper func()
diff --git a/libgo/go/net/interface.go b/libgo/go/net/interface.go
index 9c7b5da8fe9..52b857c65f1 100644
--- a/libgo/go/net/interface.go
+++ b/libgo/go/net/interface.go
@@ -1,10 +1,14 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
-import "errors"
+import (
+	"errors"
+	"sync"
+	"time"
+)
 
 var (
 	errInvalidInterface         = errors.New("invalid network interface")
@@ -15,7 +19,7 @@ var (
 )
 
 // Interface represents a mapping between network interface name
-// and index.  It also represents network interface facility
+// and index. It also represents network interface facility
 // information.
 type Interface struct {
 	Index        int          // positive integer that starts at one, zero is never used
@@ -88,9 +92,12 @@ func (ifi *Interface) MulticastAddrs() ([]Addr, error) {
 func Interfaces() ([]Interface, error) {
 	ift, err := interfaceTable(0)
 	if err != nil {
-		err = &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
+		return nil, &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
 	}
-	return ift, err
+	if len(ift) != 0 {
+		zoneCache.update(ift)
+	}
+	return ift, nil
 }
 
 // InterfaceAddrs returns a list of the system's network interface
@@ -137,6 +144,9 @@ func InterfaceByName(name string) (*Interface, error) {
 	if err != nil {
 		return nil, &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: err}
 	}
+	if len(ift) != 0 {
+		zoneCache.update(ift)
+	}
 	for _, ifi := range ift {
 		if name == ifi.Name {
 			return &ifi, nil
@@ -144,3 +154,68 @@ func InterfaceByName(name string) (*Interface, error) {
 	}
 	return nil, &OpError{Op: "route", Net: "ip+net", Source: nil, Addr: nil, Err: errNoSuchInterface}
 }
+
+// An ipv6ZoneCache represents a cache holding partial network
+// interface information. It is used for reducing the cost of IPv6
+// addressing scope zone resolution.
+type ipv6ZoneCache struct {
+	sync.RWMutex                // guard the following
+	lastFetched  time.Time      // last time routing information was fetched
+	toIndex      map[string]int // interface name to its index
+	toName       map[int]string // interface index to its name
+}
+
+var zoneCache = ipv6ZoneCache{
+	toIndex: make(map[string]int),
+	toName:  make(map[int]string),
+}
+
+func (zc *ipv6ZoneCache) update(ift []Interface) {
+	zc.Lock()
+	defer zc.Unlock()
+	now := time.Now()
+	if zc.lastFetched.After(now.Add(-60 * time.Second)) {
+		return
+	}
+	zc.lastFetched = now
+	if len(ift) == 0 {
+		var err error
+		if ift, err = interfaceTable(0); err != nil {
+			return
+		}
+	}
+	zc.toIndex = make(map[string]int, len(ift))
+	zc.toName = make(map[int]string, len(ift))
+	for _, ifi := range ift {
+		zc.toIndex[ifi.Name] = ifi.Index
+		zc.toName[ifi.Index] = ifi.Name
+	}
+}
+
+func zoneToString(zone int) string {
+	if zone == 0 {
+		return ""
+	}
+	zoneCache.update(nil)
+	zoneCache.RLock()
+	defer zoneCache.RUnlock()
+	name, ok := zoneCache.toName[zone]
+	if !ok {
+		name = uitoa(uint(zone))
+	}
+	return name
+}
+
+func zoneToInt(zone string) int {
+	if zone == "" {
+		return 0
+	}
+	zoneCache.update(nil)
+	zoneCache.RLock()
+	defer zoneCache.RUnlock()
+	index, ok := zoneCache.toIndex[zone]
+	if !ok {
+		index, _, _ = dtoi(zone, 0)
+	}
+	return index
+}
diff --git a/libgo/go/net/interface_bsd.go b/libgo/go/net/interface_bsd.go
index 208f37f9fd3..35b1c268159 100644
--- a/libgo/go/net/interface_bsd.go
+++ b/libgo/go/net/interface_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,74 +7,54 @@
 package net
 
 import (
-	"os"
 	"syscall"
-	"unsafe"
+
+	"golang_org/x/net/route"
 )
 
 // If the ifindex is zero, interfaceTable returns mappings of all
-// network interfaces.  Otherwise it returns a mapping of a specific
+// network interfaces. Otherwise it returns a mapping of a specific
 // interface.
 func interfaceTable(ifindex int) ([]Interface, error) {
-	tab, err := syscall.RouteRIB(syscall.NET_RT_IFLIST, ifindex)
+	msgs, err := interfaceMessages(ifindex)
 	if err != nil {
-		return nil, os.NewSyscallError("routerib", err)
+		return nil, err
 	}
-	msgs, err := syscall.ParseRoutingMessage(tab)
-	if err != nil {
-		return nil, os.NewSyscallError("parseroutingmessage", err)
+	n := len(msgs)
+	if ifindex != 0 {
+		n = 1
 	}
-	return parseInterfaceTable(ifindex, msgs)
-}
-
-func parseInterfaceTable(ifindex int, msgs []syscall.RoutingMessage) ([]Interface, error) {
-	var ift []Interface
-loop:
+	ift := make([]Interface, n)
+	n = 0
 	for _, m := range msgs {
 		switch m := m.(type) {
-		case *syscall.InterfaceMessage:
-			if ifindex == 0 || ifindex == int(m.Header.Index) {
-				ifi, err := newLink(m)
-				if err != nil {
-					return nil, err
-				}
-				ift = append(ift, *ifi)
-				if ifindex == int(m.Header.Index) {
-					break loop
+		case *route.InterfaceMessage:
+			if ifindex != 0 && ifindex != m.Index {
+				continue
+			}
+			ift[n].Index = m.Index
+			ift[n].Name = m.Name
+			ift[n].Flags = linkFlags(m.Flags)
+			if sa, ok := m.Addrs[syscall.RTAX_IFP].(*route.LinkAddr); ok && len(sa.Addr) > 0 {
+				ift[n].HardwareAddr = make([]byte, len(sa.Addr))
+				copy(ift[n].HardwareAddr, sa.Addr)
+			}
+			for _, sys := range m.Sys() {
+				if imx, ok := sys.(*route.InterfaceMetrics); ok {
+					ift[n].MTU = imx.MTU
+					break
 				}
 			}
+			n++
+			if ifindex == m.Index {
+				return ift[:n], nil
+			}
 		}
 	}
-	return ift, nil
-}
-
-func newLink(m *syscall.InterfaceMessage) (*Interface, error) {
-	sas, err := syscall.ParseRoutingSockaddr(m)
-	if err != nil {
-		return nil, os.NewSyscallError("parseroutingsockaddr", err)
-	}
-	ifi := &Interface{Index: int(m.Header.Index), Flags: linkFlags(m.Header.Flags)}
-	sa, _ := sas[syscall.RTAX_IFP].(*syscall.SockaddrDatalink)
-	if sa != nil {
-		// NOTE: SockaddrDatalink.Data is minimum work area,
-		// can be larger.
-		m.Data = m.Data[unsafe.Offsetof(sa.Data):]
-		var name [syscall.IFNAMSIZ]byte
-		for i := 0; i < int(sa.Nlen); i++ {
-			name[i] = byte(m.Data[i])
-		}
-		ifi.Name = string(name[:sa.Nlen])
-		ifi.MTU = int(m.Header.Data.Mtu)
-		addr := make([]byte, sa.Alen)
-		for i := 0; i < int(sa.Alen); i++ {
-			addr[i] = byte(m.Data[int(sa.Nlen)+i])
-		}
-		ifi.HardwareAddr = addr[:sa.Alen]
-	}
-	return ifi, nil
+	return ift[:n], nil
 }
 
-func linkFlags(rawFlags int32) Flags {
+func linkFlags(rawFlags int) Flags {
 	var f Flags
 	if rawFlags&syscall.IFF_UP != 0 {
 		f |= FlagUp
@@ -95,81 +75,44 @@ func linkFlags(rawFlags int32) Flags {
 }
 
 // If the ifi is nil, interfaceAddrTable returns addresses for all
-// network interfaces.  Otherwise it returns addresses for a specific
+// network interfaces. Otherwise it returns addresses for a specific
 // interface.
 func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
 	index := 0
 	if ifi != nil {
 		index = ifi.Index
 	}
-	tab, err := syscall.RouteRIB(syscall.NET_RT_IFLIST, index)
-	if err != nil {
-		return nil, os.NewSyscallError("routerib", err)
-	}
-	msgs, err := syscall.ParseRoutingMessage(tab)
+	msgs, err := interfaceMessages(index)
 	if err != nil {
-		return nil, os.NewSyscallError("parseroutingmessage", err)
+		return nil, err
 	}
-	var ift []Interface
-	if index == 0 {
-		ift, err = parseInterfaceTable(index, msgs)
-		if err != nil {
-			return nil, err
-		}
-	}
-	var ifat []Addr
+	ifat := make([]Addr, 0, len(msgs))
 	for _, m := range msgs {
 		switch m := m.(type) {
-		case *syscall.InterfaceAddrMessage:
-			if index == 0 || index == int(m.Header.Index) {
-				if index == 0 {
-					var err error
-					ifi, err = interfaceByIndex(ift, int(m.Header.Index))
-					if err != nil {
-						return nil, err
-					}
-				}
-				ifa, err := newAddr(ifi, m)
-				if err != nil {
-					return nil, err
-				}
-				if ifa != nil {
-					ifat = append(ifat, ifa)
-				}
+		case *route.InterfaceAddrMessage:
+			if index != 0 && index != m.Index {
+				continue
+			}
+			var mask IPMask
+			switch sa := m.Addrs[syscall.RTAX_NETMASK].(type) {
+			case *route.Inet4Addr:
+				mask = IPv4Mask(sa.IP[0], sa.IP[1], sa.IP[2], sa.IP[3])
+			case *route.Inet6Addr:
+				mask = make(IPMask, IPv6len)
+				copy(mask, sa.IP[:])
+			}
+			var ip IP
+			switch sa := m.Addrs[syscall.RTAX_IFA].(type) {
+			case *route.Inet4Addr:
+				ip = IPv4(sa.IP[0], sa.IP[1], sa.IP[2], sa.IP[3])
+			case *route.Inet6Addr:
+				ip = make(IP, IPv6len)
+				copy(ip, sa.IP[:])
+			}
+			if ip != nil && mask != nil { // NetBSD may contain route.LinkAddr
+				ifat = append(ifat, &IPNet{IP: ip, Mask: mask})
 			}
 		}
 	}
 	return ifat, nil
 }
-
-func newAddr(ifi *Interface, m *syscall.InterfaceAddrMessage) (*IPNet, error) {
-	sas, err := syscall.ParseRoutingSockaddr(m)
-	if err != nil {
-		return nil, os.NewSyscallError("parseroutingsockaddr", err)
-	}
-	ifa := &IPNet{}
-	switch sa := sas[syscall.RTAX_NETMASK].(type) {
-	case *syscall.SockaddrInet4:
-		ifa.Mask = IPv4Mask(sa.Addr[0], sa.Addr[1], sa.Addr[2], sa.Addr[3])
-	case *syscall.SockaddrInet6:
-		ifa.Mask = make(IPMask, IPv6len)
-		copy(ifa.Mask, sa.Addr[:])
-	}
-	switch sa := sas[syscall.RTAX_IFA].(type) {
-	case *syscall.SockaddrInet4:
-		ifa.IP = IPv4(sa.Addr[0], sa.Addr[1], sa.Addr[2], sa.Addr[3])
-	case *syscall.SockaddrInet6:
-		ifa.IP = make(IP, IPv6len)
-		copy(ifa.IP, sa.Addr[:])
-		// NOTE: KAME based IPv6 protcol stack usually embeds
-		// the interface index in the interface-local or
-		// link-local address as the kernel-internal form.
-		if ifa.IP.IsLinkLocalUnicast() {
-			ifa.IP[2], ifa.IP[3] = 0, 0
-		}
-	}
-	if ifa.IP == nil || ifa.Mask == nil {
-		return nil, nil // Sockaddrs contain syscall.SockaddrDatalink on NetBSD
-	}
-	return ifa, nil
-}
diff --git a/libgo/go/net/interface_bsdvar.go b/libgo/go/net/interface_bsdvar.go
new file mode 100644
index 00000000000..0b84ca37d4a
--- /dev/null
+++ b/libgo/go/net/interface_bsdvar.go
@@ -0,0 +1,28 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build dragonfly netbsd openbsd
+
+package net
+
+import (
+	"syscall"
+
+	"golang_org/x/net/route"
+)
+
+func interfaceMessages(ifindex int) ([]route.Message, error) {
+	rib, err := route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_IFLIST, ifindex)
+	if err != nil {
+		return nil, err
+	}
+	return route.ParseRIB(syscall.NET_RT_IFLIST, rib)
+}
+
+// interfaceMulticastAddrTable returns addresses for a specific
+// interface.
+func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
+	// TODO(mikio): Implement this like other platforms.
+	return nil, nil
+}
diff --git a/libgo/go/net/interface_darwin.go b/libgo/go/net/interface_darwin.go
index b7a333849d1..2ec8e1cc6ef 100644
--- a/libgo/go/net/interface_darwin.go
+++ b/libgo/go/net/interface_darwin.go
@@ -1,62 +1,53 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
-	"os"
 	"syscall"
+
+	"golang_org/x/net/route"
 )
 
+func interfaceMessages(ifindex int) ([]route.Message, error) {
+	rib, err := route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_IFLIST, ifindex)
+	if err != nil {
+		return nil, err
+	}
+	return route.ParseRIB(syscall.NET_RT_IFLIST, rib)
+}
+
 // interfaceMulticastAddrTable returns addresses for a specific
 // interface.
 func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
-	tab, err := syscall.RouteRIB(syscall.NET_RT_IFLIST2, ifi.Index)
+	rib, err := route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_IFLIST2, ifi.Index)
 	if err != nil {
-		return nil, os.NewSyscallError("routerib", err)
+		return nil, err
 	}
-	msgs, err := syscall.ParseRoutingMessage(tab)
+	msgs, err := route.ParseRIB(syscall.NET_RT_IFLIST2, rib)
 	if err != nil {
-		return nil, os.NewSyscallError("parseroutingmessage", err)
+		return nil, err
 	}
-	var ifmat []Addr
+	ifmat := make([]Addr, 0, len(msgs))
 	for _, m := range msgs {
 		switch m := m.(type) {
-		case *syscall.InterfaceMulticastAddrMessage:
-			if ifi.Index == int(m.Header.Index) {
-				ifma, err := newMulticastAddr(ifi, m)
-				if err != nil {
-					return nil, err
-				}
-				if ifma != nil {
-					ifmat = append(ifmat, ifma)
-				}
+		case *route.InterfaceMulticastAddrMessage:
+			if ifi.Index != m.Index {
+				continue
+			}
+			var ip IP
+			switch sa := m.Addrs[syscall.RTAX_IFA].(type) {
+			case *route.Inet4Addr:
+				ip = IPv4(sa.IP[0], sa.IP[1], sa.IP[2], sa.IP[3])
+			case *route.Inet6Addr:
+				ip = make(IP, IPv6len)
+				copy(ip, sa.IP[:])
+			}
+			if ip != nil {
+				ifmat = append(ifmat, &IPAddr{IP: ip})
 			}
 		}
 	}
 	return ifmat, nil
 }
-
-func newMulticastAddr(ifi *Interface, m *syscall.InterfaceMulticastAddrMessage) (*IPAddr, error) {
-	sas, err := syscall.ParseRoutingSockaddr(m)
-	if err != nil {
-		return nil, os.NewSyscallError("parseroutingsockaddr", err)
-	}
-	switch sa := sas[syscall.RTAX_IFA].(type) {
-	case *syscall.SockaddrInet4:
-		return &IPAddr{IP: IPv4(sa.Addr[0], sa.Addr[1], sa.Addr[2], sa.Addr[3])}, nil
-	case *syscall.SockaddrInet6:
-		ifma := IPAddr{IP: make(IP, IPv6len)}
-		copy(ifma.IP, sa.Addr[:])
-		// NOTE: KAME based IPv6 protcol stack usually embeds
-		// the interface index in the interface-local or
-		// link-local address as the kernel-internal form.
-		if ifma.IP.IsInterfaceLocalMulticast() || ifma.IP.IsLinkLocalMulticast() {
-			ifma.IP[2], ifma.IP[3] = 0, 0
-		}
-		return &ifma, nil
-	default:
-		return nil, nil
-	}
-}
diff --git a/libgo/go/net/interface_dragonfly.go b/libgo/go/net/interface_dragonfly.go
deleted file mode 100644
index c9ce5a7ac15..00000000000
--- a/libgo/go/net/interface_dragonfly.go
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package net
-
-// interfaceMulticastAddrTable returns addresses for a specific
-// interface.
-func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
-	// TODO(mikio): Implement this like other platforms.
-	return nil, nil
-}
diff --git a/libgo/go/net/interface_freebsd.go b/libgo/go/net/interface_freebsd.go
index c42d90b7403..8a7d6f67c03 100644
--- a/libgo/go/net/interface_freebsd.go
+++ b/libgo/go/net/interface_freebsd.go
@@ -1,62 +1,58 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
-	"os"
 	"syscall"
+
+	"golang_org/x/net/route"
 )
 
+func interfaceMessages(ifindex int) ([]route.Message, error) {
+	typ := route.RIBType(syscall.NET_RT_IFLISTL)
+	rib, err := route.FetchRIB(syscall.AF_UNSPEC, typ, ifindex)
+	if err != nil {
+		typ = route.RIBType(syscall.NET_RT_IFLIST)
+		rib, err = route.FetchRIB(syscall.AF_UNSPEC, typ, ifindex)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return route.ParseRIB(typ, rib)
+}
+
 // interfaceMulticastAddrTable returns addresses for a specific
 // interface.
 func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
-	tab, err := syscall.RouteRIB(syscall.NET_RT_IFMALIST, ifi.Index)
+	rib, err := route.FetchRIB(syscall.AF_UNSPEC, syscall.NET_RT_IFMALIST, ifi.Index)
 	if err != nil {
-		return nil, os.NewSyscallError("routerib", err)
+		return nil, err
 	}
-	msgs, err := syscall.ParseRoutingMessage(tab)
+	msgs, err := route.ParseRIB(syscall.NET_RT_IFMALIST, rib)
 	if err != nil {
-		return nil, os.NewSyscallError("parseroutingmessage", err)
+		return nil, err
 	}
-	var ifmat []Addr
+	ifmat := make([]Addr, 0, len(msgs))
 	for _, m := range msgs {
 		switch m := m.(type) {
-		case *syscall.InterfaceMulticastAddrMessage:
-			if ifi.Index == int(m.Header.Index) {
-				ifma, err := newMulticastAddr(ifi, m)
-				if err != nil {
-					return nil, err
-				}
-				if ifma != nil {
-					ifmat = append(ifmat, ifma)
-				}
+		case *route.InterfaceMulticastAddrMessage:
+			if ifi.Index != m.Index {
+				continue
+			}
+			var ip IP
+			switch sa := m.Addrs[syscall.RTAX_IFA].(type) {
+			case *route.Inet4Addr:
+				ip = IPv4(sa.IP[0], sa.IP[1], sa.IP[2], sa.IP[3])
+			case *route.Inet6Addr:
+				ip = make(IP, IPv6len)
+				copy(ip, sa.IP[:])
+			}
+			if ip != nil {
+				ifmat = append(ifmat, &IPAddr{IP: ip})
 			}
 		}
 	}
 	return ifmat, nil
 }
-
-func newMulticastAddr(ifi *Interface, m *syscall.InterfaceMulticastAddrMessage) (*IPAddr, error) {
-	sas, err := syscall.ParseRoutingSockaddr(m)
-	if err != nil {
-		return nil, os.NewSyscallError("parseroutingsockaddr", err)
-	}
-	switch sa := sas[syscall.RTAX_IFA].(type) {
-	case *syscall.SockaddrInet4:
-		return &IPAddr{IP: IPv4(sa.Addr[0], sa.Addr[1], sa.Addr[2], sa.Addr[3])}, nil
-	case *syscall.SockaddrInet6:
-		ifma := IPAddr{IP: make(IP, IPv6len)}
-		copy(ifma.IP, sa.Addr[:])
-		// NOTE: KAME based IPv6 protcol stack usually embeds
-		// the interface index in the interface-local or
-		// link-local address as the kernel-internal form.
-		if ifma.IP.IsInterfaceLocalMulticast() || ifma.IP.IsLinkLocalMulticast() {
-			ifma.IP[2], ifma.IP[3] = 0, 0
-		}
-		return &ifma, nil
-	default:
-		return nil, nil
-	}
-}
diff --git a/libgo/go/net/interface_linux.go b/libgo/go/net/interface_linux.go
index ef2042920ed..5e391b28b0f 100644
--- a/libgo/go/net/interface_linux.go
+++ b/libgo/go/net/interface_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -11,7 +11,7 @@ import (
 )
 
 // If the ifindex is zero, interfaceTable returns mappings of all
-// network interfaces.  Otherwise it returns a mapping of a specific
+// network interfaces. Otherwise it returns a mapping of a specific
 // interface.
 func interfaceTable(ifindex int) ([]Interface, error) {
 	tab, err := syscall.NetlinkRIB(syscall.RTM_GETLINK, syscall.AF_UNSPEC)
@@ -115,7 +115,7 @@ func linkFlags(rawFlags uint32) Flags {
 }
 
 // If the ifi is nil, interfaceAddrTable returns addresses for all
-// network interfaces.  Otherwise it returns addresses for a specific
+// network interfaces. Otherwise it returns addresses for a specific
 // interface.
 func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
 	tab, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
diff --git a/libgo/go/net/interface_netbsd.go b/libgo/go/net/interface_netbsd.go
deleted file mode 100644
index c9ce5a7ac15..00000000000
--- a/libgo/go/net/interface_netbsd.go
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package net
-
-// interfaceMulticastAddrTable returns addresses for a specific
-// interface.
-func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
-	// TODO(mikio): Implement this like other platforms.
-	return nil, nil
-}
diff --git a/libgo/go/net/interface_openbsd.go b/libgo/go/net/interface_openbsd.go
deleted file mode 100644
index c9ce5a7ac15..00000000000
--- a/libgo/go/net/interface_openbsd.go
+++ /dev/null
@@ -1,12 +0,0 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package net
-
-// interfaceMulticastAddrTable returns addresses for a specific
-// interface.
-func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
-	// TODO(mikio): Implement this like other platforms.
-	return nil, nil
-}
diff --git a/libgo/go/net/interface_stub.go b/libgo/go/net/interface_stub.go
index c38fb7f7651..f64174c62ee 100644
--- a/libgo/go/net/interface_stub.go
+++ b/libgo/go/net/interface_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,14 +7,14 @@
 package net
 
 // If the ifindex is zero, interfaceTable returns mappings of all
-// network interfaces.  Otherwise it returns a mapping of a specific
+// network interfaces. Otherwise it returns a mapping of a specific
 // interface.
 func interfaceTable(ifindex int) ([]Interface, error) {
 	return nil, nil
 }
 
 // If the ifi is nil, interfaceAddrTable returns addresses for all
-// network interfaces.  Otherwise it returns addresses for a specific
+// network interfaces. Otherwise it returns addresses for a specific
 // interface.
 func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
 	return nil, nil
diff --git a/libgo/go/net/interface_test.go b/libgo/go/net/interface_test.go
index 7bdd9241503..4c695b902a2 100644
--- a/libgo/go/net/interface_test.go
+++ b/libgo/go/net/interface_test.go
@@ -1,17 +1,18 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"fmt"
 	"reflect"
 	"runtime"
 	"testing"
 )
 
 // loopbackInterface returns an available logical network interface
-// for loopback tests.  It returns nil if no suitable interface is
+// for loopback tests. It returns nil if no suitable interface is
 // found.
 func loopbackInterface() *Interface {
 	ift, err := Interfaces()
@@ -47,20 +48,11 @@ func ipv6LinkLocalUnicastAddr(ifi *Interface) string {
 	return ""
 }
 
-type routeStats struct {
-	loop  int // # of active loopback interfaces
-	other int // # of active other interfaces
-
-	uni4, uni6     int // # of active connected unicast, anycast routes
-	multi4, multi6 int // # of active connected multicast route clones
-}
-
 func TestInterfaces(t *testing.T) {
 	ift, err := Interfaces()
 	if err != nil {
 		t.Fatal(err)
 	}
-	var stats routeStats
 	for _, ifi := range ift {
 		ifxi, err := InterfaceByIndex(ifi.Index)
 		if err != nil {
@@ -76,56 +68,7 @@ func TestInterfaces(t *testing.T) {
 		if !reflect.DeepEqual(ifxn, &ifi) {
 			t.Errorf("got %v; want %v", ifxn, ifi)
 		}
-		t.Logf("%q: flags %q, ifindex %v, mtu %v", ifi.Name, ifi.Flags.String(), ifi.Index, ifi.MTU)
-		t.Logf("hardware address %q", ifi.HardwareAddr.String())
-		if ifi.Flags&FlagUp != 0 {
-			if ifi.Flags&FlagLoopback != 0 {
-				stats.loop++
-			} else {
-				stats.other++
-			}
-		}
-		n4, n6 := testInterfaceAddrs(t, &ifi)
-		stats.uni4 += n4
-		stats.uni6 += n6
-		n4, n6 = testInterfaceMulticastAddrs(t, &ifi)
-		stats.multi4 += n4
-		stats.multi6 += n6
-	}
-	switch runtime.GOOS {
-	case "nacl", "plan9", "solaris":
-	default:
-		// Test the existence of connected unicast routes for
-		// IPv4.
-		if supportsIPv4 && stats.loop+stats.other > 0 && stats.uni4 == 0 {
-			t.Errorf("num IPv4 unicast routes = 0; want >0; summary: %+v", stats)
-		}
-		// Test the existence of connected unicast routes for
-		// IPv6. We can assume the existence of ::1/128 when
-		// at least one looopback interface is installed.
-		if supportsIPv6 && stats.loop > 0 && stats.uni6 == 0 {
-			t.Errorf("num IPv6 unicast routes = 0; want >0; summary: %+v", stats)
-		}
-	}
-	switch runtime.GOOS {
-	case "dragonfly", "nacl", "netbsd", "openbsd", "plan9", "solaris":
-	default:
-		// Test the existence of connected multicast route
-		// clones for IPv4. Unlike IPv6, IPv4 multicast
-		// capability is not a mandatory feature, and so this
-		// test is disabled.
-		//if supportsIPv4 && stats.loop > 0 && stats.uni4 > 1 && stats.multi4 == 0 {
-		//	t.Errorf("num IPv4 multicast route clones = 0; want >0; summary: %+v", stats)
-		//}
-		// Test the existence of connected multicast route
-		// clones for IPv6. Some platform never uses loopback
-		// interface as the nexthop for multicast routing.
-		// We can assume the existence of connected multicast
-		// route clones when at least two connected unicast
-		// routes, ::1/128 and other, are installed.
-		if supportsIPv6 && stats.loop > 0 && stats.uni6 > 1 && stats.multi6 == 0 {
-			t.Errorf("num IPv6 multicast route clones = 0; want >0; summary: %+v", stats)
-		}
+		t.Logf("%s: flags=%v index=%d mtu=%d hwaddr=%v", ifi.Name, ifi.Flags, ifi.Index, ifi.MTU, ifi.HardwareAddr)
 	}
 }
 
@@ -134,132 +77,217 @@ func TestInterfaceAddrs(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	var stats routeStats
-	for _, ifi := range ift {
-		if ifi.Flags&FlagUp != 0 {
-			if ifi.Flags&FlagLoopback != 0 {
-				stats.loop++
-			} else {
-				stats.other++
-			}
-		}
-	}
+	ifStats := interfaceStats(ift)
 	ifat, err := InterfaceAddrs()
 	if err != nil {
 		t.Fatal(err)
 	}
-	stats.uni4, stats.uni6 = testAddrs(t, ifat)
-	// Test the existence of connected unicast routes for IPv4.
-	if supportsIPv4 && stats.loop+stats.other > 0 && stats.uni4 == 0 {
-		t.Errorf("num IPv4 unicast routes = 0; want >0; summary: %+v", stats)
+	uniStats, err := validateInterfaceUnicastAddrs(ifat)
+	if err != nil {
+		t.Fatal(err)
 	}
-	// Test the existence of connected unicast routes for IPv6.
-	// We can assume the existence of ::1/128 when at least one
-	// looopback interface is installed.
-	if supportsIPv6 && stats.loop > 0 && stats.uni6 == 0 {
-		t.Errorf("num IPv6 unicast routes = 0; want >0; summary: %+v", stats)
+	if err := checkUnicastStats(ifStats, uniStats); err != nil {
+		t.Fatal(err)
 	}
 }
 
-func testInterfaceAddrs(t *testing.T, ifi *Interface) (naf4, naf6 int) {
-	ifat, err := ifi.Addrs()
+func TestInterfaceUnicastAddrs(t *testing.T) {
+	ift, err := Interfaces()
+	if err != nil {
+		t.Fatal(err)
+	}
+	ifStats := interfaceStats(ift)
 	if err != nil {
 		t.Fatal(err)
 	}
-	return testAddrs(t, ifat)
+	var uniStats routeStats
+	for _, ifi := range ift {
+		ifat, err := ifi.Addrs()
+		if err != nil {
+			t.Fatal(ifi, err)
+		}
+		stats, err := validateInterfaceUnicastAddrs(ifat)
+		if err != nil {
+			t.Fatal(ifi, err)
+		}
+		uniStats.ipv4 += stats.ipv4
+		uniStats.ipv6 += stats.ipv6
+	}
+	if err := checkUnicastStats(ifStats, &uniStats); err != nil {
+		t.Fatal(err)
+	}
 }
 
-func testInterfaceMulticastAddrs(t *testing.T, ifi *Interface) (nmaf4, nmaf6 int) {
-	ifmat, err := ifi.MulticastAddrs()
+func TestInterfaceMulticastAddrs(t *testing.T) {
+	ift, err := Interfaces()
+	if err != nil {
+		t.Fatal(err)
+	}
+	ifStats := interfaceStats(ift)
+	ifat, err := InterfaceAddrs()
+	if err != nil {
+		t.Fatal(err)
+	}
+	uniStats, err := validateInterfaceUnicastAddrs(ifat)
 	if err != nil {
 		t.Fatal(err)
 	}
-	return testMulticastAddrs(t, ifmat)
+	var multiStats routeStats
+	for _, ifi := range ift {
+		ifmat, err := ifi.MulticastAddrs()
+		if err != nil {
+			t.Fatal(ifi, err)
+		}
+		stats, err := validateInterfaceMulticastAddrs(ifmat)
+		if err != nil {
+			t.Fatal(ifi, err)
+		}
+		multiStats.ipv4 += stats.ipv4
+		multiStats.ipv6 += stats.ipv6
+	}
+	if err := checkMulticastStats(ifStats, uniStats, &multiStats); err != nil {
+		t.Fatal(err)
+	}
 }
 
-func testAddrs(t *testing.T, ifat []Addr) (naf4, naf6 int) {
+type ifStats struct {
+	loop  int // # of active loopback interfaces
+	other int // # of active other interfaces
+}
+
+func interfaceStats(ift []Interface) *ifStats {
+	var stats ifStats
+	for _, ifi := range ift {
+		if ifi.Flags&FlagUp != 0 {
+			if ifi.Flags&FlagLoopback != 0 {
+				stats.loop++
+			} else {
+				stats.other++
+			}
+		}
+	}
+	return &stats
+}
+
+type routeStats struct {
+	ipv4, ipv6 int // # of active connected unicast, anycast or multicast routes
+}
+
+func validateInterfaceUnicastAddrs(ifat []Addr) (*routeStats, error) {
+	// Note: BSD variants allow assigning any IPv4/IPv6 address
+	// prefix to IP interface. For example,
+	//   - 0.0.0.0/0 through 255.255.255.255/32
+	//   - ::/0 through ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff/128
+	// In other words, there is no tightly-coupled combination of
+	// interface address prefixes and connected routes.
+	stats := new(routeStats)
 	for _, ifa := range ifat {
 		switch ifa := ifa.(type) {
 		case *IPNet:
-			if ifa == nil || ifa.IP == nil || ifa.IP.IsUnspecified() || ifa.IP.IsMulticast() || ifa.Mask == nil {
-				t.Errorf("unexpected value: %#v", ifa)
-				continue
+			if ifa == nil || ifa.IP == nil || ifa.IP.IsMulticast() || ifa.Mask == nil {
+				return nil, fmt.Errorf("unexpected value: %#v", ifa)
 			}
 			if len(ifa.IP) != IPv6len {
-				t.Errorf("should be internal representation either IPv6 or IPv6 IPv4-mapped address: %#v", ifa)
-				continue
+				return nil, fmt.Errorf("should be internal representation either IPv6 or IPv4-mapped IPv6 address: %#v", ifa)
 			}
 			prefixLen, maxPrefixLen := ifa.Mask.Size()
 			if ifa.IP.To4() != nil {
 				if 0 >= prefixLen || prefixLen > 8*IPv4len || maxPrefixLen != 8*IPv4len {
-					t.Errorf("unexpected prefix length: %d/%d", prefixLen, maxPrefixLen)
-					continue
+					return nil, fmt.Errorf("unexpected prefix length: %d/%d for %#v", prefixLen, maxPrefixLen, ifa)
 				}
 				if ifa.IP.IsLoopback() && (prefixLen != 8 && prefixLen != 8*IPv4len) { // see RFC 1122
-					t.Errorf("unexpected prefix length for IPv4 loopback: %d/%d", prefixLen, maxPrefixLen)
-					continue
+					return nil, fmt.Errorf("unexpected prefix length: %d/%d for %#v", prefixLen, maxPrefixLen, ifa)
 				}
-				naf4++
+				stats.ipv4++
 			}
 			if ifa.IP.To16() != nil && ifa.IP.To4() == nil {
 				if 0 >= prefixLen || prefixLen > 8*IPv6len || maxPrefixLen != 8*IPv6len {
-					t.Errorf("unexpected prefix length: %d/%d", prefixLen, maxPrefixLen)
-					continue
+					return nil, fmt.Errorf("unexpected prefix length: %d/%d for %#v", prefixLen, maxPrefixLen, ifa)
 				}
 				if ifa.IP.IsLoopback() && prefixLen != 8*IPv6len { // see RFC 4291
-					t.Errorf("unexpected prefix length for IPv6 loopback: %d/%d", prefixLen, maxPrefixLen)
-					continue
+					return nil, fmt.Errorf("unexpected prefix length: %d/%d for %#v", prefixLen, maxPrefixLen, ifa)
 				}
-				naf6++
+				stats.ipv6++
 			}
-			t.Logf("interface address %q", ifa.String())
 		case *IPAddr:
-			if ifa == nil || ifa.IP == nil || ifa.IP.IsUnspecified() || ifa.IP.IsMulticast() {
-				t.Errorf("unexpected value: %#v", ifa)
-				continue
+			if ifa == nil || ifa.IP == nil || ifa.IP.IsMulticast() {
+				return nil, fmt.Errorf("unexpected value: %#v", ifa)
 			}
 			if len(ifa.IP) != IPv6len {
-				t.Errorf("should be internal representation either IPv6 or IPv6 IPv4-mapped address: %#v", ifa)
-				continue
+				return nil, fmt.Errorf("should be internal representation either IPv6 or IPv4-mapped IPv6 address: %#v", ifa)
 			}
 			if ifa.IP.To4() != nil {
-				naf4++
+				stats.ipv4++
 			}
 			if ifa.IP.To16() != nil && ifa.IP.To4() == nil {
-				naf6++
+				stats.ipv6++
 			}
-			t.Logf("interface address %s", ifa.String())
 		default:
-			t.Errorf("unexpected type: %T", ifa)
+			return nil, fmt.Errorf("unexpected type: %T", ifa)
 		}
 	}
-	return
+	return stats, nil
 }
 
-func testMulticastAddrs(t *testing.T, ifmat []Addr) (nmaf4, nmaf6 int) {
-	for _, ifma := range ifmat {
-		switch ifma := ifma.(type) {
+func validateInterfaceMulticastAddrs(ifat []Addr) (*routeStats, error) {
+	stats := new(routeStats)
+	for _, ifa := range ifat {
+		switch ifa := ifa.(type) {
 		case *IPAddr:
-			if ifma == nil || ifma.IP == nil || ifma.IP.IsUnspecified() || !ifma.IP.IsMulticast() {
-				t.Errorf("unexpected value: %+v", ifma)
-				continue
+			if ifa == nil || ifa.IP == nil || ifa.IP.IsUnspecified() || !ifa.IP.IsMulticast() {
+				return nil, fmt.Errorf("unexpected value: %#v", ifa)
 			}
-			if len(ifma.IP) != IPv6len {
-				t.Errorf("should be internal representation either IPv6 or IPv6 IPv4-mapped address: %#v", ifma)
-				continue
+			if len(ifa.IP) != IPv6len {
+				return nil, fmt.Errorf("should be internal representation either IPv6 or IPv4-mapped IPv6 address: %#v", ifa)
 			}
-			if ifma.IP.To4() != nil {
-				nmaf4++
+			if ifa.IP.To4() != nil {
+				stats.ipv4++
 			}
-			if ifma.IP.To16() != nil && ifma.IP.To4() == nil {
-				nmaf6++
+			if ifa.IP.To16() != nil && ifa.IP.To4() == nil {
+				stats.ipv6++
 			}
-			t.Logf("joined group address %q", ifma.String())
 		default:
-			t.Errorf("unexpected type: %T", ifma)
+			return nil, fmt.Errorf("unexpected type: %T", ifa)
+		}
+	}
+	return stats, nil
+}
+
+func checkUnicastStats(ifStats *ifStats, uniStats *routeStats) error {
+	// Test the existence of connected unicast routes for IPv4.
+	if supportsIPv4 && ifStats.loop+ifStats.other > 0 && uniStats.ipv4 == 0 {
+		return fmt.Errorf("num IPv4 unicast routes = 0; want >0; summary: %+v, %+v", ifStats, uniStats)
+	}
+	// Test the existence of connected unicast routes for IPv6.
+	// We can assume the existence of ::1/128 when at least one
+	// loopback interface is installed.
+	if supportsIPv6 && ifStats.loop > 0 && uniStats.ipv6 == 0 {
+		return fmt.Errorf("num IPv6 unicast routes = 0; want >0; summary: %+v, %+v", ifStats, uniStats)
+	}
+	return nil
+}
+
+func checkMulticastStats(ifStats *ifStats, uniStats, multiStats *routeStats) error {
+	switch runtime.GOOS {
+	case "dragonfly", "nacl", "netbsd", "openbsd", "plan9", "solaris":
+	default:
+		// Test the existence of connected multicast route
+		// clones for IPv4. Unlike IPv6, IPv4 multicast
+		// capability is not a mandatory feature, and so IPv4
+		// multicast validation is ignored and we only check
+		// IPv6 below.
+		//
+		// Test the existence of connected multicast route
+		// clones for IPv6. Some platform never uses loopback
+		// interface as the nexthop for multicast routing.
+		// We can assume the existence of connected multicast
+		// route clones when at least two connected unicast
+		// routes, ::1/128 and other, are installed.
+		if supportsIPv6 && ifStats.loop > 0 && uniStats.ipv6 > 1 && multiStats.ipv6 == 0 {
+			return fmt.Errorf("num IPv6 multicast route clones = 0; want >0; summary: %+v, %+v, %+v", ifStats, uniStats, multiStats)
 		}
 	}
-	return
+	return nil
 }
 
 func BenchmarkInterfaces(b *testing.B) {
diff --git a/libgo/go/net/interface_windows.go b/libgo/go/net/interface_windows.go
index 4d6bcdf4c76..8b976e585f3 100644
--- a/libgo/go/net/interface_windows.go
+++ b/libgo/go/net/interface_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -61,7 +61,7 @@ func adapterAddresses() ([]*windows.IpAdapterAddresses, error) {
 }
 
 // If the ifindex is zero, interfaceTable returns mappings of all
-// network interfaces.  Otherwise it returns a mapping of a specific
+// network interfaces. Otherwise it returns a mapping of a specific
 // interface.
 func interfaceTable(ifindex int) ([]Interface, error) {
 	aas, err := adapterAddresses()
@@ -116,7 +116,7 @@ func interfaceTable(ifindex int) ([]Interface, error) {
 }
 
 // If the ifi is nil, interfaceAddrTable returns addresses for all
-// network interfaces.  Otherwise it returns addresses for a specific
+// network interfaces. Otherwise it returns addresses for a specific
 // interface.
 func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
 	aas, err := adapterAddresses()
diff --git a/libgo/go/net/internal/socktest/switch.go b/libgo/go/net/internal/socktest/switch.go
index 8bef06b97c8..3c37b6ff807 100644
--- a/libgo/go/net/internal/socktest/switch.go
+++ b/libgo/go/net/internal/socktest/switch.go
@@ -121,7 +121,7 @@ const (
 	FilterSocket        FilterType = iota // for Socket
 	FilterConnect                         // for Connect or ConnectEx
 	FilterListen                          // for Listen
-	FilterAccept                          // for Accept or Accept4
+	FilterAccept                          // for Accept, Accept4 or AcceptEx
 	FilterGetsockoptInt                   // for GetsockoptInt
 	FilterClose                           // for Close or Closesocket
 )
diff --git a/libgo/go/net/internal/socktest/sys_windows.go b/libgo/go/net/internal/socktest/sys_windows.go
index e61bf2be605..2e3d2bc7fce 100644
--- a/libgo/go/net/internal/socktest/sys_windows.go
+++ b/libgo/go/net/internal/socktest/sys_windows.go
@@ -154,3 +154,33 @@ func (sw *Switch) Listen(s syscall.Handle, backlog int) (err error) {
 	sw.stats.getLocked(so.Cookie).Listened++
 	return nil
 }
+
+// AcceptEx wraps syscall.AcceptEx.
+func (sw *Switch) AcceptEx(ls syscall.Handle, as syscall.Handle, b *byte, rxdatalen uint32, laddrlen uint32, raddrlen uint32, rcvd *uint32, overlapped *syscall.Overlapped) error {
+	so := sw.sockso(ls)
+	if so == nil {
+		return syscall.AcceptEx(ls, as, b, rxdatalen, laddrlen, raddrlen, rcvd, overlapped)
+	}
+	sw.fmu.RLock()
+	f, _ := sw.fltab[FilterAccept]
+	sw.fmu.RUnlock()
+
+	af, err := f.apply(so)
+	if err != nil {
+		return err
+	}
+	so.Err = syscall.AcceptEx(ls, as, b, rxdatalen, laddrlen, raddrlen, rcvd, overlapped)
+	if err = af.apply(so); err != nil {
+		return err
+	}
+
+	sw.smu.Lock()
+	defer sw.smu.Unlock()
+	if so.Err != nil {
+		sw.stats.getLocked(so.Cookie).AcceptFailed++
+		return so.Err
+	}
+	nso := sw.addLocked(as, so.Cookie.Family(), so.Cookie.Type(), so.Cookie.Protocol())
+	sw.stats.getLocked(nso.Cookie).Accepted++
+	return nil
+}
diff --git a/libgo/go/net/ip.go b/libgo/go/net/ip.go
index cc004d60729..d0c82630b57 100644
--- a/libgo/go/net/ip.go
+++ b/libgo/go/net/ip.go
@@ -252,9 +252,11 @@ func (ip IP) Mask(mask IPMask) IP {
 }
 
 // String returns the string form of the IP address ip.
-// If the address is an IPv4 address, the string representation
-// is dotted decimal ("74.125.19.99").  Otherwise the representation
-// is IPv6 ("2001:4860:0:2001::68").
+// It returns one of 4 forms:
+//   - "<nil>", if ip has length 0
+//   - dotted decimal ("192.0.2.1"), if ip is an IPv4 or IP4-mapped IPv6 address
+//   - IPv6 ("2001:db8::1"), if ip is a valid IPv6 address
+//   - the hexadecimal form of ip, without punctuation, if no other cases apply
 func (ip IP) String() string {
 	p := ip
 
@@ -270,7 +272,7 @@ func (ip IP) String() string {
 			uitoa(uint(p4[3]))
 	}
 	if len(p) != IPv6len {
-		return "?"
+		return "?" + hexString(ip)
 	}
 
 	// Find longest run of zeros.
@@ -312,6 +314,14 @@ func (ip IP) String() string {
 	return string(b)
 }
 
+func hexString(b []byte) string {
+	s := make([]byte, len(b)*2)
+	for i, tn := range b {
+		s[i*2], s[i*2+1] = hexDigit[tn>>4], hexDigit[tn&0xf]
+	}
+	return string(s)
+}
+
 // ipEmptyString is like ip.String except that it returns
 // an empty string when ip is unset.
 func ipEmptyString(ip IP) string {
@@ -328,7 +338,7 @@ func (ip IP) MarshalText() ([]byte, error) {
 		return []byte(""), nil
 	}
 	if len(ip) != IPv4len && len(ip) != IPv6len {
-		return nil, &AddrError{Err: "invalid IP address", Addr: ip.String()}
+		return nil, &AddrError{Err: "invalid IP address", Addr: hexString(ip)}
 	}
 	return []byte(ip.String()), nil
 }
@@ -377,6 +387,10 @@ func bytesEqual(x, y []byte) bool {
 	return true
 }
 
+func (ip IP) matchAddrFamily(x IP) bool {
+	return ip.To4() != nil && x.To4() != nil || ip.To16() != nil && ip.To4() == nil && x.To16() != nil && x.To4() == nil
+}
+
 // If mask is a sequence of 1 bits followed by 0 bits,
 // return the number of 1 bits.
 func simpleMaskLength(mask IPMask) int {
@@ -422,11 +436,7 @@ func (m IPMask) String() string {
 	if len(m) == 0 {
 		return "<nil>"
 	}
-	buf := make([]byte, len(m)*2)
-	for i, b := range m {
-		buf[i*2], buf[i*2+1] = hexDigit[b>>4], hexDigit[b&0xf]
-	}
-	return string(buf)
+	return hexString(m)
 }
 
 func networkNumberAndMask(n *IPNet) (ip IP, m IPMask) {
@@ -473,12 +483,12 @@ func (n *IPNet) Contains(ip IP) bool {
 // Network returns the address's network name, "ip+net".
 func (n *IPNet) Network() string { return "ip+net" }
 
-// String returns the CIDR notation of n like "192.168.100.1/24"
-// or "2001:DB8::/48" as defined in RFC 4632 and RFC 4291.
+// String returns the CIDR notation of n like "192.0.2.1/24"
+// or "2001:db8::/48" as defined in RFC 4632 and RFC 4291.
 // If the mask is not in the canonical form, it returns the
 // string which consists of an IP address, followed by a slash
 // character and a mask expressed as hexadecimal form with no
-// punctuation like "192.168.100.1/c000ff00".
+// punctuation like "198.51.100.1/c000ff00".
 func (n *IPNet) String() string {
 	nn, m := networkNumberAndMask(n)
 	if nn == nil || m == nil {
@@ -631,8 +641,8 @@ func parseIPv6(s string, zoneAllowed bool) (ip IP, zone string) {
 }
 
 // ParseIP parses s as an IP address, returning the result.
-// The string s can be in dotted decimal ("74.125.19.99")
-// or IPv6 ("2001:4860:0:2001::68") form.
+// The string s can be in dotted decimal ("192.0.2.1")
+// or IPv6 ("2001:db8::68") form.
 // If s is not a valid textual representation of an IP address,
 // ParseIP returns nil.
 func ParseIP(s string) IP {
@@ -649,12 +659,12 @@ func ParseIP(s string) IP {
 }
 
 // ParseCIDR parses s as a CIDR notation IP address and mask,
-// like "192.168.100.1/24" or "2001:DB8::/48", as defined in
+// like "192.0.2.0/24" or "2001:db8::/32", as defined in
 // RFC 4632 and RFC 4291.
 //
 // It returns the IP address and the network implied by the IP
-// and mask.  For example, ParseCIDR("192.168.100.1/16") returns
-// the IP address 192.168.100.1 and the network 192.168.0.0/16.
+// and mask. For example, ParseCIDR("198.51.100.1/24") returns
+// the IP address 198.51.100.1 and the network 198.51.100.0/24.
 func ParseCIDR(s string) (IP, *IPNet, error) {
 	i := byteIndex(s, '/')
 	if i < 0 {
diff --git a/libgo/go/net/ip_test.go b/libgo/go/net/ip_test.go
index 3d95a73c097..b6ac26da05b 100644
--- a/libgo/go/net/ip_test.go
+++ b/libgo/go/net/ip_test.go
@@ -5,6 +5,7 @@
 package net
 
 import (
+	"bytes"
 	"reflect"
 	"runtime"
 	"testing"
@@ -124,30 +125,119 @@ func TestMarshalEmptyIP(t *testing.T) {
 }
 
 var ipStringTests = []struct {
-	in  IP
-	out string // see RFC 5952
+	in  IP     // see RFC 791 and RFC 4291
+	str string // see RFC 791, RFC 4291 and RFC 5952
+	byt []byte
+	error
 }{
-	{IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0x1, 0x23, 0, 0x12, 0, 0x1}, "2001:db8::123:12:1"},
-	{IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x1}, "2001:db8::1"},
-	{IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0x1, 0, 0, 0, 0x1, 0, 0, 0, 0x1}, "2001:db8:0:1:0:1:0:1"},
-	{IP{0x20, 0x1, 0xd, 0xb8, 0, 0x1, 0, 0, 0, 0x1, 0, 0, 0, 0x1, 0, 0}, "2001:db8:1:0:1:0:1:0"},
-	{IP{0x20, 0x1, 0, 0, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0x1}, "2001::1:0:0:1"},
-	{IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0}, "2001:db8:0:0:1::"},
-	{IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0x1}, "2001:db8::1:0:0:1"},
-	{IP{0x20, 0x1, 0xD, 0xB8, 0, 0, 0, 0, 0, 0xA, 0, 0xB, 0, 0xC, 0, 0xD}, "2001:db8::a:b:c:d"},
-	{IPv4(192, 168, 0, 1), "192.168.0.1"},
-	{nil, ""},
+	// IPv4 address
+	{
+		IP{192, 0, 2, 1},
+		"192.0.2.1",
+		[]byte("192.0.2.1"),
+		nil,
+	},
+	{
+		IP{0, 0, 0, 0},
+		"0.0.0.0",
+		[]byte("0.0.0.0"),
+		nil,
+	},
+
+	// IPv4-mapped IPv6 address
+	{
+		IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 192, 0, 2, 1},
+		"192.0.2.1",
+		[]byte("192.0.2.1"),
+		nil,
+	},
+	{
+		IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 0, 0, 0, 0},
+		"0.0.0.0",
+		[]byte("0.0.0.0"),
+		nil,
+	},
+
+	// IPv6 address
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0x1, 0x23, 0, 0x12, 0, 0x1},
+		"2001:db8::123:12:1",
+		[]byte("2001:db8::123:12:1"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x1},
+		"2001:db8::1",
+		[]byte("2001:db8::1"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0x1, 0, 0, 0, 0x1, 0, 0, 0, 0x1},
+		"2001:db8:0:1:0:1:0:1",
+		[]byte("2001:db8:0:1:0:1:0:1"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0x1, 0, 0, 0, 0x1, 0, 0, 0, 0x1, 0, 0},
+		"2001:db8:1:0:1:0:1:0",
+		[]byte("2001:db8:1:0:1:0:1:0"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0, 0, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0x1},
+		"2001::1:0:0:1",
+		[]byte("2001::1:0:0:1"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0},
+		"2001:db8:0:0:1::",
+		[]byte("2001:db8:0:0:1::"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0x1, 0, 0, 0, 0, 0, 0x1},
+		"2001:db8::1:0:0:1",
+		[]byte("2001:db8::1:0:0:1"),
+		nil,
+	},
+	{
+		IP{0x20, 0x1, 0xd, 0xb8, 0, 0, 0, 0, 0, 0xa, 0, 0xb, 0, 0xc, 0, 0xd},
+		"2001:db8::a:b:c:d",
+		[]byte("2001:db8::a:b:c:d"),
+		nil,
+	},
+	{
+		IPv6unspecified,
+		"::",
+		[]byte("::"),
+		nil,
+	},
+
+	// IP wildcard equivalent address in Dial/Listen API
+	{
+		nil,
+		"<nil>",
+		nil,
+		nil,
+	},
+
+	// Opaque byte sequence
+	{
+		IP{0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef},
+		"?0123456789abcdef",
+		nil,
+		&AddrError{Err: "invalid IP address", Addr: "0123456789abcdef"},
+	},
 }
 
 func TestIPString(t *testing.T) {
 	for _, tt := range ipStringTests {
-		if tt.in != nil {
-			if out := tt.in.String(); out != tt.out {
-				t.Errorf("IP.String(%v) = %q, want %q", tt.in, out, tt.out)
-			}
+		if out := tt.in.String(); out != tt.str {
+			t.Errorf("IP.String(%v) = %q, want %q", tt.in, out, tt.str)
 		}
-		if out, err := tt.in.MarshalText(); string(out) != tt.out || err != nil {
-			t.Errorf("IP.MarshalText(%v) = %q, %v, want %q, nil", tt.in, out, err, tt.out)
+		if out, err := tt.in.MarshalText(); !bytes.Equal(out, tt.byt) || !reflect.DeepEqual(err, tt.error) {
+			t.Errorf("IP.MarshalText(%v) = %v, %v, want %v, %v", tt.in, out, err, tt.byt, tt.error)
 		}
 	}
 }
@@ -379,8 +469,8 @@ var splitJoinTests = []struct {
 	{"", "0", ":0"},
 
 	{"google.com", "https%foo", "google.com:https%foo"}, // Go 1.0 behavior
-	{"127.0.0.1", "", "127.0.0.1:"},                     // Go 1.0 behaviour
-	{"www.google.com", "", "www.google.com:"},           // Go 1.0 behaviour
+	{"127.0.0.1", "", "127.0.0.1:"},                     // Go 1.0 behavior
+	{"www.google.com", "", "www.google.com:"},           // Go 1.0 behavior
 }
 
 var splitFailureTests = []struct {
@@ -421,13 +511,16 @@ func TestSplitHostPort(t *testing.T) {
 		}
 	}
 	for _, tt := range splitFailureTests {
-		if _, _, err := SplitHostPort(tt.hostPort); err == nil {
+		if host, port, err := SplitHostPort(tt.hostPort); err == nil {
 			t.Errorf("SplitHostPort(%q) should have failed", tt.hostPort)
 		} else {
 			e := err.(*AddrError)
 			if e.Err != tt.err {
 				t.Errorf("SplitHostPort(%q) = _, _, %q; want %q", tt.hostPort, e.Err, tt.err)
 			}
+			if host != "" || port != "" {
+				t.Errorf("SplitHostPort(%q) = %q, %q, err; want %q, %q, err on failure", tt.hostPort, host, port, "", "")
+			}
 		}
 	}
 }
diff --git a/libgo/go/net/iprawsock.go b/libgo/go/net/iprawsock.go
index f02df7fa8d1..173b3cb4114 100644
--- a/libgo/go/net/iprawsock.go
+++ b/libgo/go/net/iprawsock.go
@@ -1,9 +1,14 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
+import (
+	"context"
+	"syscall"
+)
+
 // IPAddr represents the address of an IP end point.
 type IPAddr struct {
 	IP   IP
@@ -45,7 +50,7 @@ func ResolveIPAddr(net, addr string) (*IPAddr, error) {
 	if net == "" { // a hint wildcard for Go 1.0 undocumented behavior
 		net = "ip"
 	}
-	afnet, _, err := parseNetwork(net)
+	afnet, _, err := parseNetwork(context.Background(), net)
 	if err != nil {
 		return nil, err
 	}
@@ -54,9 +59,136 @@ func ResolveIPAddr(net, addr string) (*IPAddr, error) {
 	default:
 		return nil, UnknownNetworkError(net)
 	}
-	addrs, err := internetAddrList(afnet, addr, noDeadline)
+	addrs, err := internetAddrList(context.Background(), afnet, addr)
 	if err != nil {
 		return nil, err
 	}
 	return addrs.first(isIPv4).(*IPAddr), nil
 }
+
+// IPConn is the implementation of the Conn and PacketConn interfaces
+// for IP network connections.
+type IPConn struct {
+	conn
+}
+
+// ReadFromIP reads an IP packet from c, copying the payload into b.
+// It returns the number of bytes copied into b and the return address
+// that was on the packet.
+//
+// ReadFromIP can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetReadDeadline.
+func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
+	if !c.ok() {
+		return 0, nil, syscall.EINVAL
+	}
+	n, addr, err := c.readFrom(b)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return n, addr, err
+}
+
+// ReadFrom implements the PacketConn ReadFrom method.
+func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
+	if !c.ok() {
+		return 0, nil, syscall.EINVAL
+	}
+	n, addr, err := c.readFrom(b)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	if addr == nil {
+		return n, nil, err
+	}
+	return n, addr, err
+}
+
+// ReadMsgIP reads a packet from c, copying the payload into b and the
+// associated out-of-band data into oob. It returns the number of
+// bytes copied into b, the number of bytes copied into oob, the flags
+// that were set on the packet and the source address of the packet.
+func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
+	if !c.ok() {
+		return 0, 0, 0, nil, syscall.EINVAL
+	}
+	n, oobn, flags, addr, err = c.readMsg(b, oob)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return
+}
+
+// WriteToIP writes an IP packet to addr via c, copying the payload
+// from b.
+//
+// WriteToIP can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetWriteDeadline. On packet-oriented connections, write timeouts
+// are rare.
+func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	n, err := c.writeTo(b, addr)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	}
+	return n, err
+}
+
+// WriteTo implements the PacketConn WriteTo method.
+func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	a, ok := addr.(*IPAddr)
+	if !ok {
+		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
+	}
+	n, err := c.writeTo(b, a)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
+	}
+	return n, err
+}
+
+// WriteMsgIP writes a packet to addr via c, copying the payload from
+// b and the associated out-of-band data from oob. It returns the
+// number of payload and out-of-band bytes written.
+func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
+	if !c.ok() {
+		return 0, 0, syscall.EINVAL
+	}
+	n, oobn, err = c.writeMsg(b, oob, addr)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	}
+	return
+}
+
+func newIPConn(fd *netFD) *IPConn { return &IPConn{conn{fd}} }
+
+// DialIP connects to the remote address raddr on the network protocol
+// netProto, which must be "ip", "ip4", or "ip6" followed by a colon
+// and a protocol number or name.
+func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
+	c, err := dialIP(context.Background(), netProto, laddr, raddr)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
+
+// ListenIP listens for incoming IP packets addressed to the local
+// address laddr. The returned connection's ReadFrom and WriteTo
+// methods can be used to receive and send IP packets with per-packet
+// addressing.
+func ListenIP(netProto string, laddr *IPAddr) (*IPConn, error) {
+	c, err := listenIP(context.Background(), netProto, laddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
diff --git a/libgo/go/net/iprawsock_plan9.go b/libgo/go/net/iprawsock_plan9.go
index b027adc53a7..6aebea169ca 100644
--- a/libgo/go/net/iprawsock_plan9.go
+++ b/libgo/go/net/iprawsock_plan9.go
@@ -1,82 +1,34 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"context"
 	"syscall"
-	"time"
 )
 
-// IPConn is the implementation of the Conn and PacketConn interfaces
-// for IP network connections.
-type IPConn struct {
-	conn
+func (c *IPConn) readFrom(b []byte) (int, *IPAddr, error) {
+	return 0, nil, syscall.EPLAN9
 }
 
-// ReadFromIP reads an IP packet from c, copying the payload into b.
-// It returns the number of bytes copied into b and the return address
-// that was on the packet.
-//
-// ReadFromIP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetReadDeadline.
-func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
-	return 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (c *IPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
+	return 0, 0, 0, nil, syscall.EPLAN9
 }
 
-// ReadFrom implements the PacketConn ReadFrom method.
-func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
-	return 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (c *IPConn) writeTo(b []byte, addr *IPAddr) (int, error) {
+	return 0, syscall.EPLAN9
 }
 
-// ReadMsgIP reads a packet from c, copying the payload into b and the
-// associated out-of-band data into oob.  It returns the number of
-// bytes copied into b, the number of bytes copied into oob, the flags
-// that were set on the packet and the source address of the packet.
-func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
-	return 0, 0, 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (c *IPConn) writeMsg(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
+	return 0, 0, syscall.EPLAN9
 }
 
-// WriteToIP writes an IP packet to addr via c, copying the payload
-// from b.
-//
-// WriteToIP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetWriteDeadline.  On packet-oriented connections, write timeouts
-// are rare.
-func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
-	return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EPLAN9}
+func dialIP(ctx context.Context, netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
+	return nil, syscall.EPLAN9
 }
 
-// WriteTo implements the PacketConn WriteTo method.
-func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
-	return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr, Err: syscall.EPLAN9}
-}
-
-// WriteMsgIP writes a packet to addr via c, copying the payload from
-// b and the associated out-of-band data from oob.  It returns the
-// number of payload and out-of-band bytes written.
-func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
-	return 0, 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EPLAN9}
-}
-
-// DialIP connects to the remote address raddr on the network protocol
-// netProto, which must be "ip", "ip4", or "ip6" followed by a colon
-// and a protocol number or name.
-func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
-	return dialIP(netProto, laddr, raddr, noDeadline)
-}
-
-func dialIP(netProto string, laddr, raddr *IPAddr, deadline time.Time) (*IPConn, error) {
-	return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: syscall.EPLAN9}
-}
-
-// ListenIP listens for incoming IP packets addressed to the local
-// address laddr.  The returned connection's ReadFrom and WriteTo
-// methods can be used to receive and send IP packets with per-packet
-// addressing.
-func ListenIP(netProto string, laddr *IPAddr) (*IPConn, error) {
-	return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: syscall.EPLAN9}
+func listenIP(ctx context.Context, netProto string, laddr *IPAddr) (*IPConn, error) {
+	return nil, syscall.EPLAN9
 }
diff --git a/libgo/go/net/iprawsock_posix.go b/libgo/go/net/iprawsock_posix.go
index 93fee3e232e..3e0b060a8a4 100644
--- a/libgo/go/net/iprawsock_posix.go
+++ b/libgo/go/net/iprawsock_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,8 +7,8 @@
 package net
 
 import (
+	"context"
 	"syscall"
-	"time"
 )
 
 // BUG(mikio): On every POSIX platform, reads from the "ip4" network
@@ -50,25 +50,7 @@ func (a *IPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, 0, a.Zone)
 }
 
-// IPConn is the implementation of the Conn and PacketConn interfaces
-// for IP network connections.
-type IPConn struct {
-	conn
-}
-
-func newIPConn(fd *netFD) *IPConn { return &IPConn{conn{fd}} }
-
-// ReadFromIP reads an IP packet from c, copying the payload into b.
-// It returns the number of bytes copied into b and the return address
-// that was on the packet.
-//
-// ReadFromIP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetReadDeadline.
-func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
+func (c *IPConn) readFrom(b []byte) (int, *IPAddr, error) {
 	// TODO(cw,rsc): consider using readv if we know the family
 	// type to avoid the header trim/copy
 	var addr *IPAddr
@@ -80,9 +62,6 @@ func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
 	case *syscall.SockaddrInet6:
 		addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
 	}
-	if err != nil {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
 	return n, addr, err
 }
 
@@ -101,26 +80,7 @@ func stripIPv4Header(n int, b []byte) int {
 	return n - l
 }
 
-// ReadFrom implements the PacketConn ReadFrom method.
-func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
-	n, addr, err := c.ReadFromIP(b)
-	if addr == nil {
-		return n, nil, err
-	}
-	return n, addr, err
-}
-
-// ReadMsgIP reads a packet from c, copying the payload into b and the
-// associated out-of-band data into oob.  It returns the number of
-// bytes copied into b, the number of bytes copied into oob, the flags
-// that were set on the packet and the source address of the packet.
-func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
-	if !c.ok() {
-		return 0, 0, 0, nil, syscall.EINVAL
-	}
+func (c *IPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
 	var sa syscall.Sockaddr
 	n, oobn, flags, sa, err = c.fd.readMsg(b, oob)
 	switch sa := sa.(type) {
@@ -129,121 +89,70 @@ func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err
 	case *syscall.SockaddrInet6:
 		addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
 	}
-	if err != nil {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
 	return
 }
 
-// WriteToIP writes an IP packet to addr via c, copying the payload
-// from b.
-//
-// WriteToIP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetWriteDeadline.  On packet-oriented connections, write timeouts
-// are rare.
-func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
+func (c *IPConn) writeTo(b []byte, addr *IPAddr) (int, error) {
 	if c.fd.isConnected {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
+		return 0, ErrWriteToConnected
 	}
 	if addr == nil {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
+		return 0, errMissingAddress
 	}
 	sa, err := addr.sockaddr(c.fd.family)
 	if err != nil {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
-	}
-	n, err := c.fd.writeTo(b, sa)
-	if err != nil {
-		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
-	}
-	return n, err
-}
-
-// WriteTo implements the PacketConn WriteTo method.
-func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
-	a, ok := addr.(*IPAddr)
-	if !ok {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
+		return 0, err
 	}
-	return c.WriteToIP(b, a)
+	return c.fd.writeTo(b, sa)
 }
 
-// WriteMsgIP writes a packet to addr via c, copying the payload from
-// b and the associated out-of-band data from oob.  It returns the
-// number of payload and out-of-band bytes written.
-func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
-	if !c.ok() {
-		return 0, 0, syscall.EINVAL
-	}
+func (c *IPConn) writeMsg(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
 	if c.fd.isConnected {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
+		return 0, 0, ErrWriteToConnected
 	}
 	if addr == nil {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
-	}
-	var sa syscall.Sockaddr
-	sa, err = addr.sockaddr(c.fd.family)
-	if err != nil {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+		return 0, 0, errMissingAddress
 	}
-	n, oobn, err = c.fd.writeMsg(b, oob, sa)
+	sa, err := addr.sockaddr(c.fd.family)
 	if err != nil {
-		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+		return 0, 0, err
 	}
-	return
-}
-
-// DialIP connects to the remote address raddr on the network protocol
-// netProto, which must be "ip", "ip4", or "ip6" followed by a colon
-// and a protocol number or name.
-func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
-	return dialIP(netProto, laddr, raddr, noDeadline)
+	return c.fd.writeMsg(b, oob, sa)
 }
 
-func dialIP(netProto string, laddr, raddr *IPAddr, deadline time.Time) (*IPConn, error) {
-	net, proto, err := parseNetwork(netProto)
+func dialIP(ctx context.Context, netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
+	network, proto, err := parseNetwork(ctx, netProto)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
-	switch net {
+	switch network {
 	case "ip", "ip4", "ip6":
 	default:
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(netProto)}
+		return nil, UnknownNetworkError(netProto)
 	}
 	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+		return nil, errMissingAddress
 	}
-	fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_RAW, proto, "dial", noCancel)
+	fd, err := internetSocket(ctx, network, laddr, raddr, syscall.SOCK_RAW, proto, "dial")
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newIPConn(fd), nil
 }
 
-// ListenIP listens for incoming IP packets addressed to the local
-// address laddr.  The returned connection's ReadFrom and WriteTo
-// methods can be used to receive and send IP packets with per-packet
-// addressing.
-func ListenIP(netProto string, laddr *IPAddr) (*IPConn, error) {
-	net, proto, err := parseNetwork(netProto)
+func listenIP(ctx context.Context, netProto string, laddr *IPAddr) (*IPConn, error) {
+	network, proto, err := parseNetwork(ctx, netProto)
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: err}
+		return nil, err
 	}
-	switch net {
+	switch network {
 	case "ip", "ip4", "ip6":
 	default:
-		return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(netProto)}
+		return nil, UnknownNetworkError(netProto)
 	}
-	fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_RAW, proto, "listen", noCancel)
+	fd, err := internetSocket(ctx, network, laddr, nil, syscall.SOCK_RAW, proto, "listen")
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newIPConn(fd), nil
 }
diff --git a/libgo/go/net/ipraw_test.go b/libgo/go/net/iprawsock_test.go
index 5d86a9d0316..29cd4b6fd0d 100644
--- a/libgo/go/net/ipraw_test.go
+++ b/libgo/go/net/iprawsock_test.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/ipsock.go b/libgo/go/net/ipsock.go
index 55f697f622e..24daf173ace 100644
--- a/libgo/go/net/ipsock.go
+++ b/libgo/go/net/ipsock.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,8 +7,7 @@
 package net
 
 import (
-	"errors"
-	"time"
+	"context"
 )
 
 var (
@@ -22,7 +21,7 @@ var (
 
 	// supportsIPv4map reports whether the platform supports
 	// mapping an IPv4 address inside an IPv6 address at transport
-	// layer protocols.  See RFC 4291, RFC 4038 and RFC 3493.
+	// layer protocols. See RFC 4291, RFC 4038 and RFC 3493.
 	supportsIPv4map bool
 )
 
@@ -73,8 +72,6 @@ func (addrs addrList) partition(strategy func(Addr) bool) (primaries, fallbacks
 	return
 }
 
-var errNoSuitableAddress = errors.New("no suitable address found")
-
 // filterAddrList applies a filter to a list of IP addresses,
 // yielding a list of Addr objects. Known filters are nil, ipv4only,
 // and ipv6only. It returns every address when the filter is nil.
@@ -106,73 +103,65 @@ func ipv6only(addr IPAddr) bool {
 
 // SplitHostPort splits a network address of the form "host:port",
 // "[host]:port" or "[ipv6-host%zone]:port" into host or
-// ipv6-host%zone and port.  A literal address or host name for IPv6
+// ipv6-host%zone and port. A literal address or host name for IPv6
 // must be enclosed in square brackets, as in "[::1]:80",
 // "[ipv6-host]:http" or "[ipv6-host%zone]:80".
 func SplitHostPort(hostport string) (host, port string, err error) {
+	const (
+		missingPort   = "missing port in address"
+		tooManyColons = "too many colons in address"
+	)
+	addrErr := func(addr, why string) (host, port string, err error) {
+		return "", "", &AddrError{Err: why, Addr: addr}
+	}
 	j, k := 0, 0
 
 	// The port starts after the last colon.
 	i := last(hostport, ':')
 	if i < 0 {
-		goto missingPort
+		return addrErr(hostport, missingPort)
 	}
 
 	if hostport[0] == '[' {
 		// Expect the first ']' just before the last ':'.
 		end := byteIndex(hostport, ']')
 		if end < 0 {
-			err = &AddrError{Err: "missing ']' in address", Addr: hostport}
-			return
+			return addrErr(hostport, "missing ']' in address")
 		}
 		switch end + 1 {
 		case len(hostport):
 			// There can't be a ':' behind the ']' now.
-			goto missingPort
+			return addrErr(hostport, missingPort)
 		case i:
 			// The expected result.
 		default:
 			// Either ']' isn't followed by a colon, or it is
 			// followed by a colon that is not the last one.
 			if hostport[end+1] == ':' {
-				goto tooManyColons
+				return addrErr(hostport, tooManyColons)
 			}
-			goto missingPort
+			return addrErr(hostport, missingPort)
 		}
 		host = hostport[1:end]
 		j, k = 1, end+1 // there can't be a '[' resp. ']' before these positions
 	} else {
 		host = hostport[:i]
 		if byteIndex(host, ':') >= 0 {
-			goto tooManyColons
+			return addrErr(hostport, tooManyColons)
 		}
 		if byteIndex(host, '%') >= 0 {
-			goto missingBrackets
+			return addrErr(hostport, "missing brackets in address")
 		}
 	}
 	if byteIndex(hostport[j:], '[') >= 0 {
-		err = &AddrError{Err: "unexpected '[' in address", Addr: hostport}
-		return
+		return addrErr(hostport, "unexpected '[' in address")
 	}
 	if byteIndex(hostport[k:], ']') >= 0 {
-		err = &AddrError{Err: "unexpected ']' in address", Addr: hostport}
-		return
+		return addrErr(hostport, "unexpected ']' in address")
 	}
 
 	port = hostport[i+1:]
-	return
-
-missingPort:
-	err = &AddrError{Err: "missing port in address", Addr: hostport}
-	return
-
-tooManyColons:
-	err = &AddrError{Err: "too many colons in address", Addr: hostport}
-	return
-
-missingBrackets:
-	err = &AddrError{Err: "missing brackets in address", Addr: hostport}
-	return
+	return host, port, nil
 }
 
 func splitHostZone(s string) (host, zone string) {
@@ -201,7 +190,7 @@ func JoinHostPort(host, port string) string {
 // address or a DNS name, and returns a list of internet protocol
 // family addresses. The result contains at least one address when
 // error is nil.
-func internetAddrList(net, addr string, deadline time.Time) (addrList, error) {
+func internetAddrList(ctx context.Context, net, addr string) (addrList, error) {
 	var (
 		err        error
 		host, port string
@@ -249,7 +238,7 @@ func internetAddrList(net, addr string, deadline time.Time) (addrList, error) {
 		return addrList{inetaddr(IPAddr{IP: ip, Zone: zone})}, nil
 	}
 	// Try as a DNS name.
-	ips, err := lookupIPDeadline(host, deadline)
+	ips, err := lookupIPContext(ctx, host)
 	if err != nil {
 		return nil, err
 	}
@@ -262,24 +251,3 @@ func internetAddrList(net, addr string, deadline time.Time) (addrList, error) {
 	}
 	return filterAddrList(filter, ips, inetaddr)
 }
-
-func zoneToString(zone int) string {
-	if zone == 0 {
-		return ""
-	}
-	if ifi, err := InterfaceByIndex(zone); err == nil {
-		return ifi.Name
-	}
-	return uitoa(uint(zone))
-}
-
-func zoneToInt(zone string) int {
-	if zone == "" {
-		return 0
-	}
-	if ifi, err := InterfaceByName(zone); err == nil {
-		return ifi.Index
-	}
-	n, _, _ := dtoi(zone, 0)
-	return n
-}
diff --git a/libgo/go/net/ipsock_plan9.go b/libgo/go/net/ipsock_plan9.go
index 9da6ec3053b..2b84683eeb5 100644
--- a/libgo/go/net/ipsock_plan9.go
+++ b/libgo/go/net/ipsock_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,6 +7,7 @@
 package net
 
 import (
+	"context"
 	"os"
 	"syscall"
 )
@@ -39,8 +40,8 @@ func probeIPv4Stack() bool {
 	return probe(netdir+"/iproute", "4i")
 }
 
-// probeIPv6Stack returns two boolean values.  If the first boolean
-// value is true, kernel supports basic IPv6 functionality.  If the
+// probeIPv6Stack returns two boolean values. If the first boolean
+// value is true, kernel supports basic IPv6 functionality. If the
 // second boolean value is true, kernel supports IPv6 IPv4-mapping.
 func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 	// Plan 9 uses IPv6 natively, see ip(3).
@@ -99,7 +100,7 @@ func readPlan9Addr(proto, filename string) (addr Addr, err error) {
 	return addr, nil
 }
 
-func startPlan9(net string, addr Addr) (ctl *os.File, dest, proto, name string, err error) {
+func startPlan9(ctx context.Context, net string, addr Addr) (ctl *os.File, dest, proto, name string, err error) {
 	var (
 		ip   IP
 		port int
@@ -118,7 +119,7 @@ func startPlan9(net string, addr Addr) (ctl *os.File, dest, proto, name string,
 		return
 	}
 
-	clone, dest, err := queryCS1(proto, ip, port)
+	clone, dest, err := queryCS1(ctx, proto, ip, port)
 	if err != nil {
 		return
 	}
@@ -135,8 +136,8 @@ func startPlan9(net string, addr Addr) (ctl *os.File, dest, proto, name string,
 	return f, dest, proto, string(buf[:n]), nil
 }
 
-func netErr(e error) {
-	oe, ok := e.(*OpError)
+func fixErr(err error) {
+	oe, ok := err.(*OpError)
 	if !ok {
 		return
 	}
@@ -165,46 +166,71 @@ func netErr(e error) {
 	}
 }
 
-func dialPlan9(net string, laddr, raddr Addr) (fd *netFD, err error) {
-	defer func() { netErr(err) }()
-	f, dest, proto, name, err := startPlan9(net, raddr)
+func dialPlan9(ctx context.Context, net string, laddr, raddr Addr) (fd *netFD, err error) {
+	defer func() { fixErr(err) }()
+	type res struct {
+		fd  *netFD
+		err error
+	}
+	resc := make(chan res)
+	go func() {
+		testHookDialChannel()
+		fd, err := dialPlan9Blocking(ctx, net, laddr, raddr)
+		select {
+		case resc <- res{fd, err}:
+		case <-ctx.Done():
+			if fd != nil {
+				fd.Close()
+			}
+		}
+	}()
+	select {
+	case res := <-resc:
+		return res.fd, res.err
+	case <-ctx.Done():
+		return nil, mapErr(ctx.Err())
+	}
+}
+
+func dialPlan9Blocking(ctx context.Context, net string, laddr, raddr Addr) (fd *netFD, err error) {
+	f, dest, proto, name, err := startPlan9(ctx, net, raddr)
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	_, err = f.WriteString("connect " + dest)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "dial", Net: f.Name(), Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	data, err := os.OpenFile(netdir+"/"+proto+"/"+name+"/data", os.O_RDWR, 0)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	laddr, err = readPlan9Addr(proto, netdir+"/"+proto+"/"+name+"/local")
 	if err != nil {
 		data.Close()
 		f.Close()
-		return nil, &OpError{Op: "dial", Net: proto, Source: laddr, Addr: raddr, Err: err}
+		return nil, err
 	}
 	return newFD(proto, name, f, data, laddr, raddr)
 }
 
-func listenPlan9(net string, laddr Addr) (fd *netFD, err error) {
-	defer func() { netErr(err) }()
-	f, dest, proto, name, err := startPlan9(net, laddr)
+func listenPlan9(ctx context.Context, net string, laddr Addr) (fd *netFD, err error) {
+	defer func() { fixErr(err) }()
+	f, dest, proto, name, err := startPlan9(ctx, net, laddr)
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	_, err = f.WriteString("announce " + dest)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "announce", Net: proto, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	laddr, err = readPlan9Addr(proto, netdir+"/"+proto+"/"+name+"/local")
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	return newFD(proto, name, f, nil, laddr, nil)
 }
@@ -214,32 +240,32 @@ func (fd *netFD) netFD() (*netFD, error) {
 }
 
 func (fd *netFD) acceptPlan9() (nfd *netFD, err error) {
-	defer func() { netErr(err) }()
+	defer func() { fixErr(err) }()
 	if err := fd.readLock(); err != nil {
 		return nil, err
 	}
 	defer fd.readUnlock()
 	f, err := os.Open(fd.dir + "/listen")
 	if err != nil {
-		return nil, &OpError{Op: "accept", Net: fd.dir + "/listen", Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	var buf [16]byte
 	n, err := f.Read(buf[:])
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "accept", Net: fd.dir + "/listen", Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	name := string(buf[:n])
 	data, err := os.OpenFile(netdir+"/"+fd.net+"/"+name+"/data", os.O_RDWR, 0)
 	if err != nil {
 		f.Close()
-		return nil, &OpError{Op: "accept", Net: fd.net, Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	raddr, err := readPlan9Addr(fd.net, netdir+"/"+fd.net+"/"+name+"/remote")
 	if err != nil {
 		data.Close()
 		f.Close()
-		return nil, &OpError{Op: "accept", Net: fd.net, Source: nil, Addr: fd.laddr, Err: err}
+		return nil, err
 	}
 	return newFD(fd.net, name, f, data, fd.laddr, raddr)
 }
diff --git a/libgo/go/net/ipsock_posix.go b/libgo/go/net/ipsock_posix.go
index 2bddd46a156..abe90ac0e61 100644
--- a/libgo/go/net/ipsock_posix.go
+++ b/libgo/go/net/ipsock_posix.go
@@ -1,17 +1,15 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
 
-// Internet protocol family sockets for POSIX
-
 package net
 
 import (
+	"context"
 	"runtime"
 	"syscall"
-	"time"
 )
 
 // BUG(rsc,mikio): On DragonFly BSD and OpenBSD, listening on the
@@ -35,15 +33,15 @@ func probeIPv4Stack() bool {
 // Should we try to use the IPv4 socket interface if we're
 // only dealing with IPv4 sockets?  As long as the host system
 // understands IPv6, it's okay to pass IPv4 addresses to the IPv6
-// interface.  That simplifies our code and is most general.
+// interface. That simplifies our code and is most general.
 // Unfortunately, we need to run on kernels built without IPv6
-// support too.  So probe the kernel to figure it out.
+// support too. So probe the kernel to figure it out.
 //
 // probeIPv6Stack probes both basic IPv6 capability and IPv6 IPv4-
 // mapping capability which is controlled by IPV6_V6ONLY socket
 // option and/or kernel state "net.inet6.ip6.v6only".
-// It returns two boolean values.  If the first boolean value is
-// true, kernel supports basic IPv6 functionality.  If the second
+// It returns two boolean values. If the first boolean value is
+// true, kernel supports basic IPv6 functionality. If the second
 // boolean value is true, kernel supports IPv6 IPv4-mapping.
 func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 	var probes = []struct {
@@ -52,7 +50,7 @@ func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 	}{
 		// IPv6 communication capability
 		{laddr: TCPAddr{IP: ParseIP("::1")}, value: 1},
-		// IPv6 IPv4-mapped address communication capability
+		// IPv4-mapped IPv6 address communication capability
 		{laddr: TCPAddr{IP: IPv4(127, 0, 0, 1)}, value: 0},
 	}
 	var supps [2]bool
@@ -61,7 +59,7 @@ func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 		// Some released versions of DragonFly BSD pretend to
 		// accept IPV6_V6ONLY=0 successfully, but the state
 		// still stays IPV6_V6ONLY=1. Eventually DragonFly BSD
-		// stops preteding, but the transition period would
+		// stops pretending, but the transition period would
 		// cause unpredictable behavior and we need to avoid
 		// it.
 		//
@@ -93,8 +91,8 @@ func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
 }
 
 // favoriteAddrFamily returns the appropriate address family to
-// the given net, laddr, raddr and mode.  At first it figures
-// address family out from the net.  If mode indicates "listen"
+// the given net, laddr, raddr and mode. At first it figures
+// address family out from the net. If mode indicates "listen"
 // and laddr is a wildcard, it assumes that the user wants to
 // make a passive connection with a wildcard address family, both
 // AF_INET and AF_INET6, and a wildcard address like following:
@@ -155,10 +153,9 @@ func favoriteAddrFamily(net string, laddr, raddr sockaddr, mode string) (family
 }
 
 // Internet sockets (TCP, UDP, IP)
-
-func internetSocket(net string, laddr, raddr sockaddr, deadline time.Time, sotype, proto int, mode string, cancel <-chan struct{}) (fd *netFD, err error) {
+func internetSocket(ctx context.Context, net string, laddr, raddr sockaddr, sotype, proto int, mode string) (fd *netFD, err error) {
 	family, ipv6only := favoriteAddrFamily(net, laddr, raddr, mode)
-	return socket(net, family, sotype, proto, ipv6only, laddr, raddr, deadline, cancel)
+	return socket(ctx, net, family, sotype, proto, ipv6only, laddr, raddr)
 }
 
 func ipToSockaddr(family int, ip IP, port int, zone string) (syscall.Sockaddr, error) {
@@ -167,34 +164,35 @@ func ipToSockaddr(family int, ip IP, port int, zone string) (syscall.Sockaddr, e
 		if len(ip) == 0 {
 			ip = IPv4zero
 		}
-		if ip = ip.To4(); ip == nil {
+		ip4 := ip.To4()
+		if ip4 == nil {
 			return nil, &AddrError{Err: "non-IPv4 address", Addr: ip.String()}
 		}
-		sa := new(syscall.SockaddrInet4)
-		for i := 0; i < IPv4len; i++ {
-			sa.Addr[i] = ip[i]
-		}
-		sa.Port = port
+		sa := &syscall.SockaddrInet4{Port: port}
+		copy(sa.Addr[:], ip4)
 		return sa, nil
 	case syscall.AF_INET6:
-		if len(ip) == 0 {
-			ip = IPv6zero
-		}
-		// IPv4 callers use 0.0.0.0 to mean "announce on any available address".
-		// In IPv6 mode, Linux treats that as meaning "announce on 0.0.0.0",
-		// which it refuses to do.  Rewrite to the IPv6 unspecified address.
-		if ip.Equal(IPv4zero) {
+		// In general, an IP wildcard address, which is either
+		// "0.0.0.0" or "::", means the entire IP addressing
+		// space. For some historical reason, it is used to
+		// specify "any available address" on some operations
+		// of IP node.
+		//
+		// When the IP node supports IPv4-mapped IPv6 address,
+		// we allow an listener to listen to the wildcard
+		// address of both IP addressing spaces by specifying
+		// IPv6 wildcard address.
+		if len(ip) == 0 || ip.Equal(IPv4zero) {
 			ip = IPv6zero
 		}
-		if ip = ip.To16(); ip == nil {
+		// We accept any IPv6 address including IPv4-mapped
+		// IPv6 address.
+		ip6 := ip.To16()
+		if ip6 == nil {
 			return nil, &AddrError{Err: "non-IPv6 address", Addr: ip.String()}
 		}
-		sa := new(syscall.SockaddrInet6)
-		for i := 0; i < IPv6len; i++ {
-			sa.Addr[i] = ip[i]
-		}
-		sa.Port = port
-		sa.ZoneId = uint32(zoneToInt(zone))
+		sa := &syscall.SockaddrInet6{Port: port, ZoneId: uint32(zoneToInt(zone))}
+		copy(sa.Addr[:], ip6)
 		return sa, nil
 	}
 	return nil, &AddrError{Err: "invalid address family", Addr: ip.String()}
diff --git a/libgo/go/net/listen_test.go b/libgo/go/net/listen_test.go
index 51ffe672388..6037f3600df 100644
--- a/libgo/go/net/listen_test.go
+++ b/libgo/go/net/listen_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,6 +8,7 @@ package net
 
 import (
 	"fmt"
+	"internal/testenv"
 	"os"
 	"runtime"
 	"syscall"
@@ -157,7 +158,7 @@ var dualStackTCPListenerTests = []struct {
 	network2, address2 string // second listener
 	xerr               error  // expected error value, nil or other
 }{
-	// Test cases and expected results for the attemping 2nd listen on the same port
+	// Test cases and expected results for the attempting 2nd listen on the same port
 	// 1st listen                2nd listen                 darwin  freebsd  linux  openbsd
 	// ------------------------------------------------------------------------------------
 	// "tcp"  ""                 "tcp"  ""                    -        -       -       -
@@ -216,9 +217,12 @@ var dualStackTCPListenerTests = []struct {
 // TestDualStackTCPListener tests both single and double listen
 // to a test listener with various address families, different
 // listening address and same port.
+//
+// On DragonFly BSD, we expect the kernel version of node under test
+// to be greater than or equal to 4.4.
 func TestDualStackTCPListener(t *testing.T) {
 	switch runtime.GOOS {
-	case "dragonfly", "nacl", "plan9": // re-enable on dragonfly once the new IP control block management has landed
+	case "nacl", "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
 	}
 	if !supportsIPv4 || !supportsIPv6 {
@@ -301,11 +305,14 @@ var dualStackUDPListenerTests = []struct {
 }
 
 // TestDualStackUDPListener tests both single and double listen
-// to a test listener with various address families, differnet
+// to a test listener with various address families, different
 // listening address and same port.
+//
+// On DragonFly BSD, we expect the kernel version of node under test
+// to be greater than or equal to 4.4.
 func TestDualStackUDPListener(t *testing.T) {
 	switch runtime.GOOS {
-	case "dragonfly", "nacl", "plan9": // re-enable on dragonfly once the new IP control block management has landed
+	case "nacl", "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
 	}
 	if !supportsIPv4 || !supportsIPv6 {
@@ -477,13 +484,12 @@ func checkDualStackAddrFamily(fd *netFD) error {
 }
 
 func TestWildWildcardListener(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
 	}
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
 
 	defer func() {
 		if p := recover(); p != nil {
@@ -521,12 +527,17 @@ var ipv4MulticastListenerTests = []struct {
 // test listener with same address family, same group address and same
 // port.
 func TestIPv4MulticastListener(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	switch runtime.GOOS {
 	case "android", "nacl", "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
 	case "solaris":
 		t.Skipf("not supported on solaris, see golang.org/issue/7399")
 	}
+	if !supportsIPv4 {
+		t.Skip("IPv4 is not supported")
+	}
 
 	closer := func(cs []*UDPConn) {
 		for _, c := range cs {
@@ -542,7 +553,7 @@ func TestIPv4MulticastListener(t *testing.T) {
 		// routing stuff for finding out an appropriate
 		// nexthop containing both network and link layer
 		// adjacencies.
-		if ifi == nil && (testing.Short() || !*testExternal) {
+		if ifi == nil || !*testIPv4 {
 			continue
 		}
 		for _, tt := range ipv4MulticastListenerTests {
@@ -591,6 +602,8 @@ var ipv6MulticastListenerTests = []struct {
 // test listener with same address family, same group address and same
 // port.
 func TestIPv6MulticastListener(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
@@ -598,7 +611,7 @@ func TestIPv6MulticastListener(t *testing.T) {
 		t.Skipf("not supported on solaris, see issue 7399")
 	}
 	if !supportsIPv6 {
-		t.Skip("ipv6 is not supported")
+		t.Skip("IPv6 is not supported")
 	}
 	if os.Getuid() != 0 {
 		t.Skip("must be root")
@@ -618,7 +631,7 @@ func TestIPv6MulticastListener(t *testing.T) {
 		// routing stuff for finding out an appropriate
 		// nexthop containing both network and link layer
 		// adjacencies.
-		if ifi == nil && (testing.Short() || !*testExternal || !*testIPv6) {
+		if ifi == nil && !*testIPv6 {
 			continue
 		}
 		for _, tt := range ipv6MulticastListenerTests {
diff --git a/libgo/go/net/lookup.go b/libgo/go/net/lookup.go
index 7aa111ba929..c169e9e902c 100644
--- a/libgo/go/net/lookup.go
+++ b/libgo/go/net/lookup.go
@@ -1,12 +1,13 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"context"
+	"internal/nettrace"
 	"internal/singleflight"
-	"time"
 )
 
 // protocols contains minimal mappings between internet protocol
@@ -33,7 +34,7 @@ func LookupHost(host string) (addrs []string, err error) {
 	if ip := ParseIP(host); ip != nil {
 		return []string{host}, nil
 	}
-	return lookupHost(host)
+	return lookupHost(context.Background(), host)
 }
 
 // LookupIP looks up host using the local resolver.
@@ -47,7 +48,7 @@ func LookupIP(host string) (ips []IP, err error) {
 	if ip := ParseIP(host); ip != nil {
 		return []IP{ip}, nil
 	}
-	addrs, err := lookupIPMerge(host)
+	addrs, err := lookupIPMerge(context.Background(), host)
 	if err != nil {
 		return
 	}
@@ -63,9 +64,9 @@ var lookupGroup singleflight.Group
 // lookupIPMerge wraps lookupIP, but makes sure that for any given
 // host, only one lookup is in-flight at a time. The returned memory
 // is always owned by the caller.
-func lookupIPMerge(host string) (addrs []IPAddr, err error) {
+func lookupIPMerge(ctx context.Context, host string) (addrs []IPAddr, err error) {
 	addrsi, err, shared := lookupGroup.Do(host, func() (interface{}, error) {
-		return testHookLookupIP(lookupIP, host)
+		return testHookLookupIP(ctx, lookupIP, host)
 	})
 	return lookupIPReturn(addrsi, err, shared)
 }
@@ -85,52 +86,65 @@ func lookupIPReturn(addrsi interface{}, err error, shared bool) ([]IPAddr, error
 	return addrs, nil
 }
 
-// lookupIPDeadline looks up a hostname with a deadline.
-func lookupIPDeadline(host string, deadline time.Time) (addrs []IPAddr, err error) {
-	if deadline.IsZero() {
-		return lookupIPMerge(host)
+// ipAddrsEface returns an empty interface slice of addrs.
+func ipAddrsEface(addrs []IPAddr) []interface{} {
+	s := make([]interface{}, len(addrs))
+	for i, v := range addrs {
+		s[i] = v
 	}
+	return s
+}
 
-	// We could push the deadline down into the name resolution
-	// functions.  However, the most commonly used implementation
-	// calls getaddrinfo, which has no timeout.
-
-	timeout := deadline.Sub(time.Now())
-	if timeout <= 0 {
-		return nil, errTimeout
+// lookupIPContext looks up a hostname with a context.
+//
+// TODO(bradfitz): rename this function. All the other
+// build-tag-specific lookupIP funcs also take a context now, so this
+// name is no longer great. Maybe make this lookupIPMerge and ditch
+// the other one, making its callers call this instead with a
+// context.Background().
+func lookupIPContext(ctx context.Context, host string) (addrs []IPAddr, err error) {
+	trace, _ := ctx.Value(nettrace.TraceKey{}).(*nettrace.Trace)
+	if trace != nil && trace.DNSStart != nil {
+		trace.DNSStart(host)
+	}
+	// The underlying resolver func is lookupIP by default but it
+	// can be overridden by tests. This is needed by net/http, so it
+	// uses a context key instead of unexported variables.
+	resolverFunc := lookupIP
+	if alt, _ := ctx.Value(nettrace.LookupIPAltResolverKey{}).(func(context.Context, string) ([]IPAddr, error)); alt != nil {
+		resolverFunc = alt
 	}
-	t := time.NewTimer(timeout)
-	defer t.Stop()
 
 	ch := lookupGroup.DoChan(host, func() (interface{}, error) {
-		return testHookLookupIP(lookupIP, host)
+		return testHookLookupIP(ctx, resolverFunc, host)
 	})
 
 	select {
-	case <-t.C:
-		// The DNS lookup timed out for some reason.  Force
+	case <-ctx.Done():
+		// The DNS lookup timed out for some reason. Force
 		// future requests to start the DNS lookup again
 		// rather than waiting for the current lookup to
-		// complete.  See issue 8602.
+		// complete. See issue 8602.
+		err := mapErr(ctx.Err())
 		lookupGroup.Forget(host)
-
-		return nil, errTimeout
-
+		if trace != nil && trace.DNSDone != nil {
+			trace.DNSDone(nil, false, err)
+		}
+		return nil, err
 	case r := <-ch:
+		if trace != nil && trace.DNSDone != nil {
+			addrs, _ := r.Val.([]IPAddr)
+			trace.DNSDone(ipAddrsEface(addrs), r.Shared, r.Err)
+		}
 		return lookupIPReturn(r.Val, r.Err, r.Shared)
 	}
 }
 
 // LookupPort looks up the port for the given network and service.
 func LookupPort(network, service string) (port int, err error) {
-	if service == "" {
-		// Lock in the legacy behavior that an empty string
-		// means port 0. See Issue 13610.
-		return 0, nil
-	}
-	port, _, ok := dtoi(service, 0)
-	if !ok && port != big && port != -big {
-		port, err = lookupPort(network, service)
+	port, needsLookup := parsePort(service)
+	if needsLookup {
+		port, err = lookupPort(context.Background(), network, service)
 		if err != nil {
 			return 0, err
 		}
@@ -146,39 +160,39 @@ func LookupPort(network, service string) (port int, err error) {
 // LookupHost or LookupIP directly; both take care of resolving
 // the canonical name as part of the lookup.
 func LookupCNAME(name string) (cname string, err error) {
-	return lookupCNAME(name)
+	return lookupCNAME(context.Background(), name)
 }
 
 // LookupSRV tries to resolve an SRV query of the given service,
-// protocol, and domain name.  The proto is "tcp" or "udp".
+// protocol, and domain name. The proto is "tcp" or "udp".
 // The returned records are sorted by priority and randomized
 // by weight within a priority.
 //
 // LookupSRV constructs the DNS name to look up following RFC 2782.
-// That is, it looks up _service._proto.name.  To accommodate services
+// That is, it looks up _service._proto.name. To accommodate services
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
 func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
-	return lookupSRV(service, proto, name)
+	return lookupSRV(context.Background(), service, proto, name)
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
 func LookupMX(name string) (mxs []*MX, err error) {
-	return lookupMX(name)
+	return lookupMX(context.Background(), name)
 }
 
 // LookupNS returns the DNS NS records for the given domain name.
 func LookupNS(name string) (nss []*NS, err error) {
-	return lookupNS(name)
+	return lookupNS(context.Background(), name)
 }
 
 // LookupTXT returns the DNS TXT records for the given domain name.
 func LookupTXT(name string) (txts []string, err error) {
-	return lookupTXT(name)
+	return lookupTXT(context.Background(), name)
 }
 
 // LookupAddr performs a reverse lookup for the given address, returning a list
 // of names mapping to that address.
 func LookupAddr(addr string) (names []string, err error) {
-	return lookupAddr(addr)
+	return lookupAddr(context.Background(), addr)
 }
diff --git a/libgo/go/net/lookup_plan9.go b/libgo/go/net/lookup_plan9.go
index a33162882b7..3f7af2a1747 100644
--- a/libgo/go/net/lookup_plan9.go
+++ b/libgo/go/net/lookup_plan9.go
@@ -1,22 +1,24 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"context"
 	"errors"
+	"io"
 	"os"
 )
 
-func query(filename, query string, bufSize int) (res []string, err error) {
+func query(ctx context.Context, filename, query string, bufSize int) (res []string, err error) {
 	file, err := os.OpenFile(filename, os.O_RDWR, 0)
 	if err != nil {
 		return
 	}
 	defer file.Close()
 
-	_, err = file.Seek(0, 0)
+	_, err = file.Seek(0, io.SeekStart)
 	if err != nil {
 		return
 	}
@@ -24,7 +26,7 @@ func query(filename, query string, bufSize int) (res []string, err error) {
 	if err != nil {
 		return
 	}
-	_, err = file.Seek(0, 0)
+	_, err = file.Seek(0, io.SeekStart)
 	if err != nil {
 		return
 	}
@@ -39,7 +41,7 @@ func query(filename, query string, bufSize int) (res []string, err error) {
 	return
 }
 
-func queryCS(net, host, service string) (res []string, err error) {
+func queryCS(ctx context.Context, net, host, service string) (res []string, err error) {
 	switch net {
 	case "tcp4", "tcp6":
 		net = "tcp"
@@ -49,15 +51,15 @@ func queryCS(net, host, service string) (res []string, err error) {
 	if host == "" {
 		host = "*"
 	}
-	return query(netdir+"/cs", net+"!"+host+"!"+service, 128)
+	return query(ctx, netdir+"/cs", net+"!"+host+"!"+service, 128)
 }
 
-func queryCS1(net string, ip IP, port int) (clone, dest string, err error) {
+func queryCS1(ctx context.Context, net string, ip IP, port int) (clone, dest string, err error) {
 	ips := "*"
 	if len(ip) != 0 && !ip.IsUnspecified() {
 		ips = ip.String()
 	}
-	lines, err := queryCS(net, ips, itoa(port))
+	lines, err := queryCS(ctx, net, ips, itoa(port))
 	if err != nil {
 		return
 	}
@@ -69,8 +71,8 @@ func queryCS1(net string, ip IP, port int) (clone, dest string, err error) {
 	return
 }
 
-func queryDNS(addr string, typ string) (res []string, err error) {
-	return query(netdir+"/dns", addr+" "+typ, 1024)
+func queryDNS(ctx context.Context, addr string, typ string) (res []string, err error) {
+	return query(ctx, netdir+"/dns", addr+" "+typ, 1024)
 }
 
 // toLower returns a lower-case version of in. Restricting us to
@@ -96,8 +98,8 @@ func toLower(in string) string {
 
 // lookupProtocol looks up IP protocol name and returns
 // the corresponding protocol number.
-func lookupProtocol(name string) (proto int, err error) {
-	lines, err := query(netdir+"/cs", "!protocol="+toLower(name), 128)
+func lookupProtocol(ctx context.Context, name string) (proto int, err error) {
+	lines, err := query(ctx, netdir+"/cs", "!protocol="+toLower(name), 128)
 	if err != nil {
 		return 0, err
 	}
@@ -115,10 +117,10 @@ func lookupProtocol(name string) (proto int, err error) {
 	return 0, UnknownNetworkError(name)
 }
 
-func lookupHost(host string) (addrs []string, err error) {
+func lookupHost(ctx context.Context, host string) (addrs []string, err error) {
 	// Use netdir/cs instead of netdir/dns because cs knows about
 	// host names in local network (e.g. from /lib/ndb/local)
-	lines, err := queryCS("net", host, "1")
+	lines, err := queryCS(ctx, "net", host, "1")
 	if err != nil {
 		return
 	}
@@ -146,8 +148,8 @@ loop:
 	return
 }
 
-func lookupIP(host string) (addrs []IPAddr, err error) {
-	lits, err := LookupHost(host)
+func lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
+	lits, err := lookupHost(ctx, host)
 	if err != nil {
 		return
 	}
@@ -161,14 +163,14 @@ func lookupIP(host string) (addrs []IPAddr, err error) {
 	return
 }
 
-func lookupPort(network, service string) (port int, err error) {
+func lookupPort(ctx context.Context, network, service string) (port int, err error) {
 	switch network {
 	case "tcp4", "tcp6":
 		network = "tcp"
 	case "udp4", "udp6":
 		network = "udp"
 	}
-	lines, err := queryCS(network, "127.0.0.1", service)
+	lines, err := queryCS(ctx, network, "127.0.0.1", service)
 	if err != nil {
 		return
 	}
@@ -190,8 +192,8 @@ func lookupPort(network, service string) (port int, err error) {
 	return 0, unknownPortError
 }
 
-func lookupCNAME(name string) (cname string, err error) {
-	lines, err := queryDNS(name, "cname")
+func lookupCNAME(ctx context.Context, name string) (cname string, err error) {
+	lines, err := queryDNS(ctx, name, "cname")
 	if err != nil {
 		return
 	}
@@ -203,14 +205,14 @@ func lookupCNAME(name string) (cname string, err error) {
 	return "", errors.New("bad response from ndb/dns")
 }
 
-func lookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
+func lookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []*SRV, err error) {
 	var target string
 	if service == "" && proto == "" {
 		target = name
 	} else {
 		target = "_" + service + "._" + proto + "." + name
 	}
-	lines, err := queryDNS(target, "srv")
+	lines, err := queryDNS(ctx, target, "srv")
 	if err != nil {
 		return
 	}
@@ -232,8 +234,8 @@ func lookupSRV(service, proto, name string) (cname string, addrs []*SRV, err err
 	return
 }
 
-func lookupMX(name string) (mx []*MX, err error) {
-	lines, err := queryDNS(name, "mx")
+func lookupMX(ctx context.Context, name string) (mx []*MX, err error) {
+	lines, err := queryDNS(ctx, name, "mx")
 	if err != nil {
 		return
 	}
@@ -250,8 +252,8 @@ func lookupMX(name string) (mx []*MX, err error) {
 	return
 }
 
-func lookupNS(name string) (ns []*NS, err error) {
-	lines, err := queryDNS(name, "ns")
+func lookupNS(ctx context.Context, name string) (ns []*NS, err error) {
+	lines, err := queryDNS(ctx, name, "ns")
 	if err != nil {
 		return
 	}
@@ -265,8 +267,8 @@ func lookupNS(name string) (ns []*NS, err error) {
 	return
 }
 
-func lookupTXT(name string) (txt []string, err error) {
-	lines, err := queryDNS(name, "txt")
+func lookupTXT(ctx context.Context, name string) (txt []string, err error) {
+	lines, err := queryDNS(ctx, name, "txt")
 	if err != nil {
 		return
 	}
@@ -278,12 +280,12 @@ func lookupTXT(name string) (txt []string, err error) {
 	return
 }
 
-func lookupAddr(addr string) (name []string, err error) {
+func lookupAddr(ctx context.Context, addr string) (name []string, err error) {
 	arpa, err := reverseaddr(addr)
 	if err != nil {
 		return
 	}
-	lines, err := queryDNS(arpa, "ptr")
+	lines, err := queryDNS(ctx, arpa, "ptr")
 	if err != nil {
 		return
 	}
diff --git a/libgo/go/net/lookup_stub.go b/libgo/go/net/lookup_stub.go
index 5636198f881..bd096b39652 100644
--- a/libgo/go/net/lookup_stub.go
+++ b/libgo/go/net/lookup_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,44 +6,47 @@
 
 package net
 
-import "syscall"
+import (
+	"context"
+	"syscall"
+)
 
-func lookupProtocol(name string) (proto int, err error) {
+func lookupProtocol(ctx context.Context, name string) (proto int, err error) {
 	return 0, syscall.ENOPROTOOPT
 }
 
-func lookupHost(host string) (addrs []string, err error) {
+func lookupHost(ctx context.Context, host string) (addrs []string, err error) {
 	return nil, syscall.ENOPROTOOPT
 }
 
-func lookupIP(host string) (addrs []IPAddr, err error) {
+func lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
 	return nil, syscall.ENOPROTOOPT
 }
 
-func lookupPort(network, service string) (port int, err error) {
+func lookupPort(ctx context.Context, network, service string) (port int, err error) {
 	return 0, syscall.ENOPROTOOPT
 }
 
-func lookupCNAME(name string) (cname string, err error) {
+func lookupCNAME(ctx context.Context, name string) (cname string, err error) {
 	return "", syscall.ENOPROTOOPT
 }
 
-func lookupSRV(service, proto, name string) (cname string, srvs []*SRV, err error) {
+func lookupSRV(ctx context.Context, service, proto, name string) (cname string, srvs []*SRV, err error) {
 	return "", nil, syscall.ENOPROTOOPT
 }
 
-func lookupMX(name string) (mxs []*MX, err error) {
+func lookupMX(ctx context.Context, name string) (mxs []*MX, err error) {
 	return nil, syscall.ENOPROTOOPT
 }
 
-func lookupNS(name string) (nss []*NS, err error) {
+func lookupNS(ctx context.Context, name string) (nss []*NS, err error) {
 	return nil, syscall.ENOPROTOOPT
 }
 
-func lookupTXT(name string) (txts []string, err error) {
+func lookupTXT(ctx context.Context, name string) (txts []string, err error) {
 	return nil, syscall.ENOPROTOOPT
 }
 
-func lookupAddr(addr string) (ptrs []string, err error) {
+func lookupAddr(ctx context.Context, addr string) (ptrs []string, err error) {
 	return nil, syscall.ENOPROTOOPT
 }
diff --git a/libgo/go/net/lookup_test.go b/libgo/go/net/lookup_test.go
index 439496ac81d..b3aeb85afbc 100644
--- a/libgo/go/net/lookup_test.go
+++ b/libgo/go/net/lookup_test.go
@@ -6,6 +6,7 @@ package net
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"internal/testenv"
 	"runtime"
@@ -14,7 +15,7 @@ import (
 	"time"
 )
 
-func lookupLocalhost(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+func lookupLocalhost(ctx context.Context, fn func(context.Context, string) ([]IPAddr, error), host string) ([]IPAddr, error) {
 	switch host {
 	case "localhost":
 		return []IPAddr{
@@ -22,7 +23,7 @@ func lookupLocalhost(fn func(string) ([]IPAddr, error), host string) ([]IPAddr,
 			{IP: IPv6loopback},
 		}, nil
 	default:
-		return fn(host)
+		return fn(ctx, host)
 	}
 }
 
@@ -58,9 +59,10 @@ var lookupGoogleSRVTests = []struct {
 }
 
 func TestLookupGoogleSRV(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -68,6 +70,7 @@ func TestLookupGoogleSRV(t *testing.T) {
 	for _, tt := range lookupGoogleSRVTests {
 		cname, srvs, err := LookupSRV(tt.service, tt.proto, tt.name)
 		if err != nil {
+			testenv.SkipFlakyNet(t)
 			t.Fatal(err)
 		}
 		if len(srvs) == 0 {
@@ -92,9 +95,10 @@ var lookupGmailMXTests = []struct {
 }
 
 func TestLookupGmailMX(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -123,9 +127,10 @@ var lookupGmailNSTests = []struct {
 }
 
 func TestLookupGmailNS(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -133,6 +138,7 @@ func TestLookupGmailNS(t *testing.T) {
 	for _, tt := range lookupGmailNSTests {
 		nss, err := LookupNS(tt.name)
 		if err != nil {
+			testenv.SkipFlakyNet(t)
 			t.Fatal(err)
 		}
 		if len(nss) == 0 {
@@ -154,9 +160,10 @@ var lookupGmailTXTTests = []struct {
 }
 
 func TestLookupGmailTXT(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -188,9 +195,10 @@ var lookupGooglePublicDNSAddrTests = []struct {
 }
 
 func TestLookupGooglePublicDNSAddr(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !supportsIPv6 || !*testIPv4 || !*testIPv6 {
 		t.Skip("both IPv4 and IPv6 are required")
 	}
@@ -243,9 +251,10 @@ var lookupIANACNAMETests = []struct {
 }
 
 func TestLookupIANACNAME(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -269,9 +278,10 @@ var lookupGoogleHostTests = []struct {
 }
 
 func TestLookupGoogleHost(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -300,9 +310,10 @@ var lookupGoogleIPTests = []struct {
 }
 
 func TestLookupGoogleIP(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -360,22 +371,38 @@ func TestReverseAddress(t *testing.T) {
 	}
 }
 
-func TestLookupIPDeadline(t *testing.T) {
+func TestDNSFlood(t *testing.T) {
 	if !*testDNSFlood {
 		t.Skip("test disabled; use -dnsflood to enable")
 	}
 
-	const N = 5000
+	var N = 5000
+	if runtime.GOOS == "darwin" {
+		// On Darwin this test consumes kernel threads much
+		// than other platforms for some reason.
+		// When we monitor the number of allocated Ms by
+		// observing on runtime.newm calls, we can see that it
+		// easily reaches the per process ceiling
+		// kern.num_threads when CGO_ENABLED=1 and
+		// GODEBUG=netdns=go.
+		N = 500
+	}
+
 	const timeout = 3 * time.Second
+	ctxHalfTimeout, cancel := context.WithTimeout(context.Background(), timeout/2)
+	defer cancel()
+	ctxTimeout, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
 	c := make(chan error, 2*N)
 	for i := 0; i < N; i++ {
 		name := fmt.Sprintf("%d.net-test.golang.org", i)
 		go func() {
-			_, err := lookupIPDeadline(name, time.Now().Add(timeout/2))
+			_, err := lookupIPContext(ctxHalfTimeout, name)
 			c <- err
 		}()
 		go func() {
-			_, err := lookupIPDeadline(name, time.Now().Add(timeout))
+			_, err := lookupIPContext(ctxTimeout, name)
 			c <- err
 		}()
 	}
@@ -426,6 +453,10 @@ func TestLookupDotsWithLocalSource(t *testing.T) {
 		t.Skip("IPv4 is required")
 	}
 
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
+	}
+
 	for i, fn := range []func() func(){forceGoDNS, forceCgoDNS} {
 		fixup := fn()
 		if fixup == nil {
@@ -463,9 +494,10 @@ func TestLookupDotsWithLocalSource(t *testing.T) {
 }
 
 func TestLookupDotsWithRemoteSource(t *testing.T) {
-	if testing.Short() && testenv.Builder() == "" || !*testExternal {
-		t.Skip("avoid external network")
+	if testenv.Builder() == "" {
+		testenv.MustHaveExternalNetwork(t)
 	}
+
 	if !supportsIPv4 || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -483,6 +515,7 @@ func TestLookupDotsWithRemoteSource(t *testing.T) {
 func testDots(t *testing.T, mode string) {
 	names, err := LookupAddr("8.8.8.8") // Google dns server
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupAddr(8.8.8.8): %v (mode=%v)", err, mode)
 	} else {
 		for _, name := range names {
@@ -494,12 +527,16 @@ func testDots(t *testing.T, mode string) {
 	}
 
 	cname, err := LookupCNAME("www.mit.edu")
-	if err != nil || !strings.HasSuffix(cname, ".") {
-		t.Errorf("LookupCNAME(www.mit.edu) = %v, %v, want cname ending in . with trailing dot (mode=%v)", cname, err, mode)
+	if err != nil {
+		testenv.SkipFlakyNet(t)
+		t.Errorf("LookupCNAME(www.mit.edu, mode=%v): %v", mode, err)
+	} else if !strings.HasSuffix(cname, ".") {
+		t.Errorf("LookupCNAME(www.mit.edu) = %v, want cname ending in . with trailing dot (mode=%v)", cname, mode)
 	}
 
 	mxs, err := LookupMX("google.com")
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupMX(google.com): %v (mode=%v)", err, mode)
 	} else {
 		for _, mx := range mxs {
@@ -512,6 +549,7 @@ func testDots(t *testing.T, mode string) {
 
 	nss, err := LookupNS("google.com")
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupNS(google.com): %v (mode=%v)", err, mode)
 	} else {
 		for _, ns := range nss {
@@ -524,6 +562,7 @@ func testDots(t *testing.T, mode string) {
 
 	cname, srvs, err := LookupSRV("xmpp-server", "tcp", "google.com")
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupSRV(xmpp-server, tcp, google.com): %v (mode=%v)", err, mode)
 	} else {
 		if !strings.HasSuffix(cname, ".google.com.") {
@@ -574,61 +613,60 @@ func srvString(srvs []*SRV) string {
 	return buf.String()
 }
 
-var lookupPortTests = []struct {
-	network string
-	name    string
-	port    int
-	ok      bool
-}{
-	{"tcp", "0", 0, true},
-	{"tcp", "echo", 7, true},
-	{"tcp", "discard", 9, true},
-	{"tcp", "systat", 11, true},
-	{"tcp", "daytime", 13, true},
-	{"tcp", "chargen", 19, true},
-	{"tcp", "ftp-data", 20, true},
-	{"tcp", "ftp", 21, true},
-	{"tcp", "telnet", 23, true},
-	{"tcp", "smtp", 25, true},
-	{"tcp", "time", 37, true},
-	{"tcp", "domain", 53, true},
-	{"tcp", "finger", 79, true},
-	{"tcp", "42", 42, true},
-
-	{"udp", "0", 0, true},
-	{"udp", "echo", 7, true},
-	{"udp", "tftp", 69, true},
-	{"udp", "bootpc", 68, true},
-	{"udp", "bootps", 67, true},
-	{"udp", "domain", 53, true},
-	{"udp", "ntp", 123, true},
-	{"udp", "snmp", 161, true},
-	{"udp", "syslog", 514, true},
-	{"udp", "42", 42, true},
-
-	{"--badnet--", "zzz", 0, false},
-	{"tcp", "--badport--", 0, false},
-	{"tcp", "-1", 0, false},
-	{"tcp", "65536", 0, false},
-	{"udp", "-1", 0, false},
-	{"udp", "65536", 0, false},
-
-	// Issue 13610: LookupPort("tcp", "")
-	{"tcp", "", 0, true},
-	{"tcp6", "", 0, true},
-	{"tcp4", "", 0, true},
-	{"udp", "", 0, true},
-}
-
 func TestLookupPort(t *testing.T) {
+	// See http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml
+	//
+	// Please be careful about adding new mappings for testings.
+	// There are platforms having incomplete mappings for
+	// restricted resource access and security reasons.
+	type test struct {
+		network string
+		name    string
+		port    int
+		ok      bool
+	}
+	var tests = []test{
+		{"tcp", "0", 0, true},
+		{"udp", "0", 0, true},
+		{"udp", "domain", 53, true},
+
+		{"--badnet--", "zzz", 0, false},
+		{"tcp", "--badport--", 0, false},
+		{"tcp", "-1", 0, false},
+		{"tcp", "65536", 0, false},
+		{"udp", "-1", 0, false},
+		{"udp", "65536", 0, false},
+		{"tcp", "123456789", 0, false},
+
+		// Issue 13610: LookupPort("tcp", "")
+		{"tcp", "", 0, true},
+		{"tcp4", "", 0, true},
+		{"tcp6", "", 0, true},
+		{"udp", "", 0, true},
+		{"udp4", "", 0, true},
+		{"udp6", "", 0, true},
+	}
+
 	switch runtime.GOOS {
 	case "nacl":
 		t.Skipf("not supported on %s", runtime.GOOS)
+	case "android":
+		if netGo {
+			t.Skipf("not supported on %s without cgo; see golang.org/issues/14576", runtime.GOOS)
+		}
+	default:
+		tests = append(tests, test{"tcp", "http", 80, true})
 	}
 
-	for _, tt := range lookupPortTests {
-		if port, err := LookupPort(tt.network, tt.name); port != tt.port || (err == nil) != tt.ok {
-			t.Errorf("LookupPort(%q, %q) = %d, %v; want %d", tt.network, tt.name, port, err, tt.port)
+	for _, tt := range tests {
+		port, err := LookupPort(tt.network, tt.name)
+		if port != tt.port || (err == nil) != tt.ok {
+			t.Errorf("LookupPort(%q, %q) = %d, %v; want %d, error=%t", tt.network, tt.name, port, err, tt.port, !tt.ok)
+		}
+		if err != nil {
+			if perr := parseLookupPortError(err); perr != nil {
+				t.Error(perr)
+			}
 		}
 	}
 }
diff --git a/libgo/go/net/lookup_unix.go b/libgo/go/net/lookup_unix.go
index a64da8bcb50..15397e8105a 100644
--- a/libgo/go/net/lookup_unix.go
+++ b/libgo/go/net/lookup_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,7 +6,10 @@
 
 package net
 
-import "sync"
+import (
+	"context"
+	"sync"
+)
 
 var onceReadProtocols sync.Once
 
@@ -40,7 +43,7 @@ func readProtocols() {
 
 // lookupProtocol looks up IP protocol name in /etc/protocols and
 // returns correspondent protocol number.
-func lookupProtocol(name string) (int, error) {
+func lookupProtocol(_ context.Context, name string) (int, error) {
 	onceReadProtocols.Do(readProtocols)
 	proto, found := protocols[name]
 	if !found {
@@ -49,56 +52,61 @@ func lookupProtocol(name string) (int, error) {
 	return proto, nil
 }
 
-func lookupHost(host string) (addrs []string, err error) {
+func lookupHost(ctx context.Context, host string) (addrs []string, err error) {
 	order := systemConf().hostLookupOrder(host)
 	if order == hostLookupCgo {
-		if addrs, err, ok := cgoLookupHost(host); ok {
+		if addrs, err, ok := cgoLookupHost(ctx, host); ok {
 			return addrs, err
 		}
 		// cgo not available (or netgo); fall back to Go's DNS resolver
 		order = hostLookupFilesDNS
 	}
-	return goLookupHostOrder(host, order)
+	return goLookupHostOrder(ctx, host, order)
 }
 
-func lookupIP(host string) (addrs []IPAddr, err error) {
+func lookupIP(ctx context.Context, host string) (addrs []IPAddr, err error) {
 	order := systemConf().hostLookupOrder(host)
 	if order == hostLookupCgo {
-		if addrs, err, ok := cgoLookupIP(host); ok {
+		if addrs, err, ok := cgoLookupIP(ctx, host); ok {
 			return addrs, err
 		}
 		// cgo not available (or netgo); fall back to Go's DNS resolver
 		order = hostLookupFilesDNS
 	}
-	return goLookupIPOrder(host, order)
+	return goLookupIPOrder(ctx, host, order)
 }
 
-func lookupPort(network, service string) (int, error) {
+func lookupPort(ctx context.Context, network, service string) (int, error) {
+	// TODO: use the context if there ever becomes a need. Related
+	// is issue 15321. But port lookup generally just involves
+	// local files, and the os package has no context support. The
+	// files might be on a remote filesystem, though. This should
+	// probably race goroutines if ctx != context.Background().
 	if systemConf().canUseCgo() {
-		if port, err, ok := cgoLookupPort(network, service); ok {
+		if port, err, ok := cgoLookupPort(ctx, network, service); ok {
 			return port, err
 		}
 	}
 	return goLookupPort(network, service)
 }
 
-func lookupCNAME(name string) (string, error) {
+func lookupCNAME(ctx context.Context, name string) (string, error) {
 	if systemConf().canUseCgo() {
-		if cname, err, ok := cgoLookupCNAME(name); ok {
+		if cname, err, ok := cgoLookupCNAME(ctx, name); ok {
 			return cname, err
 		}
 	}
-	return goLookupCNAME(name)
+	return goLookupCNAME(ctx, name)
 }
 
-func lookupSRV(service, proto, name string) (string, []*SRV, error) {
+func lookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
 	var target string
 	if service == "" && proto == "" {
 		target = name
 	} else {
 		target = "_" + service + "._" + proto + "." + name
 	}
-	cname, rrs, err := lookup(target, dnsTypeSRV)
+	cname, rrs, err := lookup(ctx, target, dnsTypeSRV)
 	if err != nil {
 		return "", nil, err
 	}
@@ -111,8 +119,8 @@ func lookupSRV(service, proto, name string) (string, []*SRV, error) {
 	return cname, srvs, nil
 }
 
-func lookupMX(name string) ([]*MX, error) {
-	_, rrs, err := lookup(name, dnsTypeMX)
+func lookupMX(ctx context.Context, name string) ([]*MX, error) {
+	_, rrs, err := lookup(ctx, name, dnsTypeMX)
 	if err != nil {
 		return nil, err
 	}
@@ -125,8 +133,8 @@ func lookupMX(name string) ([]*MX, error) {
 	return mxs, nil
 }
 
-func lookupNS(name string) ([]*NS, error) {
-	_, rrs, err := lookup(name, dnsTypeNS)
+func lookupNS(ctx context.Context, name string) ([]*NS, error) {
+	_, rrs, err := lookup(ctx, name, dnsTypeNS)
 	if err != nil {
 		return nil, err
 	}
@@ -137,8 +145,8 @@ func lookupNS(name string) ([]*NS, error) {
 	return nss, nil
 }
 
-func lookupTXT(name string) ([]string, error) {
-	_, rrs, err := lookup(name, dnsTypeTXT)
+func lookupTXT(ctx context.Context, name string) ([]string, error) {
+	_, rrs, err := lookup(ctx, name, dnsTypeTXT)
 	if err != nil {
 		return nil, err
 	}
@@ -149,11 +157,11 @@ func lookupTXT(name string) ([]string, error) {
 	return txts, nil
 }
 
-func lookupAddr(addr string) ([]string, error) {
+func lookupAddr(ctx context.Context, addr string) ([]string, error) {
 	if systemConf().canUseCgo() {
-		if ptrs, err, ok := cgoLookupPTR(addr); ok {
+		if ptrs, err, ok := cgoLookupPTR(ctx, addr); ok {
 			return ptrs, err
 		}
 	}
-	return goLookupPTR(addr)
+	return goLookupPTR(ctx, addr)
 }
diff --git a/libgo/go/net/lookup_windows.go b/libgo/go/net/lookup_windows.go
index 13edc264e82..5f65c2d00d4 100644
--- a/libgo/go/net/lookup_windows.go
+++ b/libgo/go/net/lookup_windows.go
@@ -5,17 +5,13 @@
 package net
 
 import (
+	"context"
 	"os"
 	"runtime"
 	"syscall"
 	"unsafe"
 )
 
-var (
-	lookupPort = oldLookupPort
-	lookupIP   = oldLookupIP
-)
-
 func getprotobyname(name string) (proto int, err error) {
 	p, err := syscall.GetProtoByName(name)
 	if err != nil {
@@ -25,34 +21,41 @@ func getprotobyname(name string) (proto int, err error) {
 }
 
 // lookupProtocol looks up IP protocol name and returns correspondent protocol number.
-func lookupProtocol(name string) (int, error) {
+func lookupProtocol(ctx context.Context, name string) (int, error) {
 	// GetProtoByName return value is stored in thread local storage.
 	// Start new os thread before the call to prevent races.
 	type result struct {
 		proto int
 		err   error
 	}
-	ch := make(chan result)
+	ch := make(chan result) // unbuffered
 	go func() {
 		acquireThread()
 		defer releaseThread()
 		runtime.LockOSThread()
 		defer runtime.UnlockOSThread()
 		proto, err := getprotobyname(name)
-		ch <- result{proto: proto, err: err}
+		select {
+		case ch <- result{proto: proto, err: err}:
+		case <-ctx.Done():
+		}
 	}()
-	r := <-ch
-	if r.err != nil {
-		if proto, ok := protocols[name]; ok {
-			return proto, nil
+	select {
+	case r := <-ch:
+		if r.err != nil {
+			if proto, ok := protocols[name]; ok {
+				return proto, nil
+			}
+			r.err = &DNSError{Err: r.err.Error(), Name: name}
 		}
-		r.err = &DNSError{Err: r.err.Error(), Name: name}
+		return r.proto, r.err
+	case <-ctx.Done():
+		return 0, mapErr(ctx.Err())
 	}
-	return r.proto, r.err
 }
 
-func lookupHost(name string) ([]string, error) {
-	ips, err := LookupIP(name)
+func lookupHost(ctx context.Context, name string) ([]string, error) {
+	ips, err := lookupIP(ctx, name)
 	if err != nil {
 		return nil, err
 	}
@@ -63,121 +66,67 @@ func lookupHost(name string) ([]string, error) {
 	return addrs, nil
 }
 
-func gethostbyname(name string) (addrs []IPAddr, err error) {
-	// caller already acquired thread
-	h, err := syscall.GetHostByName(name)
-	if err != nil {
-		return nil, os.NewSyscallError("gethostbyname", err)
-	}
-	switch h.AddrType {
-	case syscall.AF_INET:
-		i := 0
-		addrs = make([]IPAddr, 100) // plenty of room to grow
-		for p := (*[100](*[4]byte))(unsafe.Pointer(h.AddrList)); i < cap(addrs) && p[i] != nil; i++ {
-			addrs[i] = IPAddr{IP: IPv4(p[i][0], p[i][1], p[i][2], p[i][3])}
-		}
-		addrs = addrs[0:i]
-	default: // TODO(vcc): Implement non IPv4 address lookups.
-		return nil, syscall.EWINDOWS
-	}
-	return addrs, nil
-}
+func lookupIP(ctx context.Context, name string) ([]IPAddr, error) {
+	// TODO(bradfitz,brainman): use ctx?
 
-func oldLookupIP(name string) ([]IPAddr, error) {
-	// GetHostByName return value is stored in thread local storage.
-	// Start new os thread before the call to prevent races.
-	type result struct {
+	type ret struct {
 		addrs []IPAddr
 		err   error
 	}
-	ch := make(chan result)
+	ch := make(chan ret, 1)
 	go func() {
 		acquireThread()
 		defer releaseThread()
-		runtime.LockOSThread()
-		defer runtime.UnlockOSThread()
-		addrs, err := gethostbyname(name)
-		ch <- result{addrs: addrs, err: err}
-	}()
-	r := <-ch
-	if r.err != nil {
-		r.err = &DNSError{Err: r.err.Error(), Name: name}
-	}
-	return r.addrs, r.err
-}
-
-func newLookupIP(name string) ([]IPAddr, error) {
-	acquireThread()
-	defer releaseThread()
-	hints := syscall.AddrinfoW{
-		Family:   syscall.AF_UNSPEC,
-		Socktype: syscall.SOCK_STREAM,
-		Protocol: syscall.IPPROTO_IP,
-	}
-	var result *syscall.AddrinfoW
-	e := syscall.GetAddrInfoW(syscall.StringToUTF16Ptr(name), nil, &hints, &result)
-	if e != nil {
-		return nil, &DNSError{Err: os.NewSyscallError("getaddrinfow", e).Error(), Name: name}
-	}
-	defer syscall.FreeAddrInfoW(result)
-	addrs := make([]IPAddr, 0, 5)
-	for ; result != nil; result = result.Next {
-		addr := unsafe.Pointer(result.Addr)
-		switch result.Family {
-		case syscall.AF_INET:
-			a := (*syscall.RawSockaddrInet4)(addr).Addr
-			addrs = append(addrs, IPAddr{IP: IPv4(a[0], a[1], a[2], a[3])})
-		case syscall.AF_INET6:
-			a := (*syscall.RawSockaddrInet6)(addr).Addr
-			zone := zoneToString(int((*syscall.RawSockaddrInet6)(addr).Scope_id))
-			addrs = append(addrs, IPAddr{IP: IP{a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15]}, Zone: zone})
-		default:
-			return nil, &DNSError{Err: syscall.EWINDOWS.Error(), Name: name}
+		hints := syscall.AddrinfoW{
+			Family:   syscall.AF_UNSPEC,
+			Socktype: syscall.SOCK_STREAM,
+			Protocol: syscall.IPPROTO_IP,
 		}
-	}
-	return addrs, nil
-}
-
-func getservbyname(network, service string) (int, error) {
-	acquireThread()
-	defer releaseThread()
-	switch network {
-	case "tcp4", "tcp6":
-		network = "tcp"
-	case "udp4", "udp6":
-		network = "udp"
-	}
-	s, err := syscall.GetServByName(service, network)
-	if err != nil {
-		return 0, os.NewSyscallError("getservbyname", err)
-	}
-	return int(syscall.Ntohs(s.Port)), nil
-}
-
-func oldLookupPort(network, service string) (int, error) {
-	// GetServByName return value is stored in thread local storage.
-	// Start new os thread before the call to prevent races.
-	type result struct {
-		port int
-		err  error
-	}
-	ch := make(chan result)
-	go func() {
-		acquireThread()
-		defer releaseThread()
-		runtime.LockOSThread()
-		defer runtime.UnlockOSThread()
-		port, err := getservbyname(network, service)
-		ch <- result{port: port, err: err}
+		var result *syscall.AddrinfoW
+		e := syscall.GetAddrInfoW(syscall.StringToUTF16Ptr(name), nil, &hints, &result)
+		if e != nil {
+			ch <- ret{err: &DNSError{Err: os.NewSyscallError("getaddrinfow", e).Error(), Name: name}}
+		}
+		defer syscall.FreeAddrInfoW(result)
+		addrs := make([]IPAddr, 0, 5)
+		for ; result != nil; result = result.Next {
+			addr := unsafe.Pointer(result.Addr)
+			switch result.Family {
+			case syscall.AF_INET:
+				a := (*syscall.RawSockaddrInet4)(addr).Addr
+				addrs = append(addrs, IPAddr{IP: IPv4(a[0], a[1], a[2], a[3])})
+			case syscall.AF_INET6:
+				a := (*syscall.RawSockaddrInet6)(addr).Addr
+				zone := zoneToString(int((*syscall.RawSockaddrInet6)(addr).Scope_id))
+				addrs = append(addrs, IPAddr{IP: IP{a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10], a[11], a[12], a[13], a[14], a[15]}, Zone: zone})
+			default:
+				ch <- ret{err: &DNSError{Err: syscall.EWINDOWS.Error(), Name: name}}
+			}
+		}
+		ch <- ret{addrs: addrs}
 	}()
-	r := <-ch
-	if r.err != nil {
-		r.err = &DNSError{Err: r.err.Error(), Name: network + "/" + service}
+	select {
+	case r := <-ch:
+		return r.addrs, r.err
+	case <-ctx.Done():
+		// TODO(bradfitz,brainman): cancel the ongoing
+		// GetAddrInfoW? It would require conditionally using
+		// GetAddrInfoEx with lpOverlapped, which requires
+		// Windows 8 or newer. I guess we'll need oldLookupIP,
+		// newLookupIP, and newerLookUP.
+		//
+		// For now we just let it finish and write to the
+		// buffered channel.
+		return nil, &DNSError{
+			Name:      name,
+			Err:       ctx.Err().Error(),
+			IsTimeout: ctx.Err() == context.DeadlineExceeded,
+		}
 	}
-	return r.port, r.err
 }
 
-func newLookupPort(network, service string) (int, error) {
+func lookupPort(ctx context.Context, network, service string) (int, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	var stype int32
@@ -213,7 +162,8 @@ func newLookupPort(network, service string) (int, error) {
 	return 0, &DNSError{Err: syscall.EINVAL.Error(), Name: network + "/" + service}
 }
 
-func lookupCNAME(name string) (string, error) {
+func lookupCNAME(ctx context.Context, name string) (string, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	var r *syscall.DNSRecord
@@ -233,7 +183,8 @@ func lookupCNAME(name string) (string, error) {
 	return absDomainName([]byte(cname)), nil
 }
 
-func lookupSRV(service, proto, name string) (string, []*SRV, error) {
+func lookupSRV(ctx context.Context, service, proto, name string) (string, []*SRV, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	var target string
@@ -258,7 +209,8 @@ func lookupSRV(service, proto, name string) (string, []*SRV, error) {
 	return absDomainName([]byte(target)), srvs, nil
 }
 
-func lookupMX(name string) ([]*MX, error) {
+func lookupMX(ctx context.Context, name string) ([]*MX, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	var r *syscall.DNSRecord
@@ -277,7 +229,8 @@ func lookupMX(name string) ([]*MX, error) {
 	return mxs, nil
 }
 
-func lookupNS(name string) ([]*NS, error) {
+func lookupNS(ctx context.Context, name string) ([]*NS, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	var r *syscall.DNSRecord
@@ -295,7 +248,8 @@ func lookupNS(name string) ([]*NS, error) {
 	return nss, nil
 }
 
-func lookupTXT(name string) ([]string, error) {
+func lookupTXT(ctx context.Context, name string) ([]string, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	var r *syscall.DNSRecord
@@ -316,7 +270,8 @@ func lookupTXT(name string) ([]string, error) {
 	return txts, nil
 }
 
-func lookupAddr(addr string) ([]string, error) {
+func lookupAddr(ctx context.Context, addr string) ([]string, error) {
+	// TODO(bradfitz): finish ctx plumbing. Nothing currently depends on this.
 	acquireThread()
 	defer releaseThread()
 	arpa, err := reverseaddr(addr)
diff --git a/libgo/go/net/mac.go b/libgo/go/net/mac.go
index 93f0b091219..f3b1694735c 100644
--- a/libgo/go/net/mac.go
+++ b/libgo/go/net/mac.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/mac_test.go b/libgo/go/net/mac_test.go
index 1ec6b287ac3..2630d190479 100644
--- a/libgo/go/net/mac_test.go
+++ b/libgo/go/net/mac_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/mail/message.go b/libgo/go/net/mail/message.go
index 923630c49ce..0c000697f7b 100644
--- a/libgo/go/net/mail/message.go
+++ b/libgo/go/net/mail/message.go
@@ -5,13 +5,15 @@
 /*
 Package mail implements parsing of mail messages.
 
-For the most part, this package follows the syntax as specified by RFC 5322.
+For the most part, this package follows the syntax as specified by RFC 5322 and
+extended by RFC 6532.
 Notable divergences:
 	* Obsolete address formats are not parsed, including addresses with
 	  embedded route information.
 	* Group addresses are not parsed.
 	* The full range of spacing (the CFWS syntax element) is not supported,
 	  such as breaking addresses across lines.
+	* No unicode normalization is performed.
 */
 package mail
 
@@ -26,6 +28,7 @@ import (
 	"net/textproto"
 	"strings"
 	"time"
+	"unicode/utf8"
 )
 
 var debug = debugT(false)
@@ -138,7 +141,7 @@ type Address struct {
 
 // Parses a single RFC 5322 address, e.g. "Barry Gibbs <bg@example.com>"
 func ParseAddress(address string) (*Address, error) {
-	return (&addrParser{s: address}).parseAddress()
+	return (&addrParser{s: address}).parseSingleAddress()
 }
 
 // ParseAddressList parses the given string as a list of addresses.
@@ -155,7 +158,7 @@ type AddressParser struct {
 // Parse parses a single RFC 5322 address of the
 // form "Gogh Fir <gf@example.com>" or "foo@example.com".
 func (p *AddressParser) Parse(address string) (*Address, error) {
-	return (&addrParser{s: address, dec: p.WordDecoder}).parseAddress()
+	return (&addrParser{s: address, dec: p.WordDecoder}).parseSingleAddress()
 }
 
 // ParseList parses the given string as a list of comma-separated addresses
@@ -168,7 +171,6 @@ func (p *AddressParser) ParseList(list string) ([]*Address, error) {
 // If the address's name contains non-ASCII characters
 // the name will be rendered according to RFC 2047.
 func (a *Address) String() string {
-
 	// Format address local@domain
 	at := strings.LastIndex(a.Address, "@")
 	var local, domain string
@@ -181,15 +183,12 @@ func (a *Address) String() string {
 	}
 
 	// Add quotes if needed
-	// TODO: rendering quoted local part and rendering printable name
-	//       should be merged in helper function.
 	quoteLocal := false
-	for i := 0; i < len(local); i++ {
-		ch := local[i]
-		if isAtext(ch, false) {
+	for i, r := range local {
+		if isAtext(r, false) {
 			continue
 		}
-		if ch == '.' {
+		if r == '.' {
 			// Dots are okay if they are surrounded by atext.
 			// We only need to check that the previous byte is
 			// not a dot, and this isn't the end of the string.
@@ -213,25 +212,16 @@ func (a *Address) String() string {
 
 	// If every character is printable ASCII, quoting is simple.
 	allPrintable := true
-	for i := 0; i < len(a.Name); i++ {
+	for _, r := range a.Name {
 		// isWSP here should actually be isFWS,
 		// but we don't support folding yet.
-		if !isVchar(a.Name[i]) && !isWSP(a.Name[i]) {
+		if !isVchar(r) && !isWSP(r) || isMultibyte(r) {
 			allPrintable = false
 			break
 		}
 	}
 	if allPrintable {
-		b := bytes.NewBufferString(`"`)
-		for i := 0; i < len(a.Name); i++ {
-			if !isQtext(a.Name[i]) && !isWSP(a.Name[i]) {
-				b.WriteByte('\\')
-			}
-			b.WriteByte(a.Name[i])
-		}
-		b.WriteString(`" `)
-		b.WriteString(s)
-		return b.String()
+		return quoteString(a.Name) + " " + s
 	}
 
 	// Text in an encoded-word in a display-name must not contain certain
@@ -269,6 +259,18 @@ func (p *addrParser) parseAddressList() ([]*Address, error) {
 	return list, nil
 }
 
+func (p *addrParser) parseSingleAddress() (*Address, error) {
+	addr, err := p.parseAddress()
+	if err != nil {
+		return nil, err
+	}
+	p.skipSpace()
+	if !p.empty() {
+		return nil, fmt.Errorf("mail: expected single address, got %q", p.s)
+	}
+	return addr, nil
+}
+
 // parseAddress parses a single RFC 5322 address at the start of p.
 func (p *addrParser) parseAddress() (addr *Address, err error) {
 	debug.Printf("parseAddress: %q", p.s)
@@ -416,29 +418,48 @@ func (p *addrParser) consumePhrase() (phrase string, err error) {
 func (p *addrParser) consumeQuotedString() (qs string, err error) {
 	// Assume first byte is '"'.
 	i := 1
-	qsb := make([]byte, 0, 10)
+	qsb := make([]rune, 0, 10)
+
+	escaped := false
+
 Loop:
 	for {
-		if i >= p.len() {
+		r, size := utf8.DecodeRuneInString(p.s[i:])
+
+		switch {
+		case size == 0:
 			return "", errors.New("mail: unclosed quoted-string")
-		}
-		switch c := p.s[i]; {
-		case c == '"':
-			break Loop
-		case c == '\\':
-			if i+1 == p.len() {
-				return "", errors.New("mail: unclosed quoted-string")
+
+		case size == 1 && r == utf8.RuneError:
+			return "", fmt.Errorf("mail: invalid utf-8 in quoted-string: %q", p.s)
+
+		case escaped:
+			//  quoted-pair = ("\" (VCHAR / WSP))
+
+			if !isVchar(r) && !isWSP(r) {
+				return "", fmt.Errorf("mail: bad character in quoted-string: %q", r)
 			}
-			qsb = append(qsb, p.s[i+1])
-			i += 2
-		case isQtext(c), c == ' ':
+
+			qsb = append(qsb, r)
+			escaped = false
+
+		case isQtext(r) || isWSP(r):
 			// qtext (printable US-ASCII excluding " and \), or
 			// FWS (almost; we're ignoring CRLF)
-			qsb = append(qsb, c)
-			i++
+			qsb = append(qsb, r)
+
+		case r == '"':
+			break Loop
+
+		case r == '\\':
+			escaped = true
+
 		default:
-			return "", fmt.Errorf("mail: bad character in quoted-string: %q", c)
+			return "", fmt.Errorf("mail: bad character in quoted-string: %q", r)
+
 		}
+
+		i += size
 	}
 	p.s = p.s[i+1:]
 	if len(qsb) == 0 {
@@ -447,26 +468,34 @@ Loop:
 	return string(qsb), nil
 }
 
-var errNonASCII = errors.New("mail: unencoded non-ASCII text in address")
-
 // consumeAtom parses an RFC 5322 atom at the start of p.
 // If dot is true, consumeAtom parses an RFC 5322 dot-atom instead.
 // If permissive is true, consumeAtom will not fail on
 // leading/trailing/double dots in the atom (see golang.org/issue/4938).
 func (p *addrParser) consumeAtom(dot bool, permissive bool) (atom string, err error) {
-	if c := p.peek(); !isAtext(c, false) {
-		if c > 127 {
-			return "", errNonASCII
+	i := 0
+
+Loop:
+	for {
+		r, size := utf8.DecodeRuneInString(p.s[i:])
+
+		switch {
+		case size == 1 && r == utf8.RuneError:
+			return "", fmt.Errorf("mail: invalid utf-8 in address: %q", p.s)
+
+		case size == 0 || !isAtext(r, dot):
+			break Loop
+
+		default:
+			i += size
+
 		}
-		return "", errors.New("mail: invalid string")
-	}
-	i := 1
-	for ; i < p.len() && isAtext(p.s[i], dot); i++ {
 	}
-	if i < p.len() && p.s[i] > 127 {
-		return "", errNonASCII
+
+	if i == 0 {
+		return "", errors.New("mail: invalid string")
 	}
-	atom, p.s = string(p.s[:i]), p.s[i:]
+	atom, p.s = p.s[:i], p.s[i:]
 	if !permissive {
 		if strings.HasPrefix(atom, ".") {
 			return "", errors.New("mail: leading dot in atom")
@@ -536,54 +565,58 @@ func (e charsetError) Error() string {
 	return fmt.Sprintf("charset not supported: %q", string(e))
 }
 
-var atextChars = []byte("ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
-	"abcdefghijklmnopqrstuvwxyz" +
-	"0123456789" +
-	"!#$%&'*+-/=?^_`{|}~")
-
-// isAtext reports whether c is an RFC 5322 atext character.
+// isAtext reports whether r is an RFC 5322 atext character.
 // If dot is true, period is included.
-func isAtext(c byte, dot bool) bool {
-	if dot && c == '.' {
-		return true
+func isAtext(r rune, dot bool) bool {
+	switch r {
+	case '.':
+		return dot
+
+	case '(', ')', '<', '>', '[', ']', ':', ';', '@', '\\', ',', '"': // RFC 5322 3.2.3. specials
+		return false
 	}
-	return bytes.IndexByte(atextChars, c) >= 0
+	return isVchar(r)
 }
 
-// isQtext reports whether c is an RFC 5322 qtext character.
-func isQtext(c byte) bool {
+// isQtext reports whether r is an RFC 5322 qtext character.
+func isQtext(r rune) bool {
 	// Printable US-ASCII, excluding backslash or quote.
-	if c == '\\' || c == '"' {
+	if r == '\\' || r == '"' {
 		return false
 	}
-	return '!' <= c && c <= '~'
+	return isVchar(r)
 }
 
-// quoteString renders a string as a RFC5322 quoted-string.
+// quoteString renders a string as an RFC 5322 quoted-string.
 func quoteString(s string) string {
 	var buf bytes.Buffer
 	buf.WriteByte('"')
-	for _, c := range s {
-		ch := byte(c)
-		if isQtext(ch) || isWSP(ch) {
-			buf.WriteByte(ch)
-		} else if isVchar(ch) {
+	for _, r := range s {
+		if isQtext(r) || isWSP(r) {
+			buf.WriteRune(r)
+		} else if isVchar(r) {
 			buf.WriteByte('\\')
-			buf.WriteByte(ch)
+			buf.WriteRune(r)
 		}
 	}
 	buf.WriteByte('"')
 	return buf.String()
 }
 
-// isVchar reports whether c is an RFC 5322 VCHAR character.
-func isVchar(c byte) bool {
+// isVchar reports whether r is an RFC 5322 VCHAR character.
+func isVchar(r rune) bool {
 	// Visible (printing) characters.
-	return '!' <= c && c <= '~'
+	return '!' <= r && r <= '~' || isMultibyte(r)
+}
+
+// isMultibyte reports whether r is a multi-byte UTF-8 character
+// as supported by RFC 6532
+func isMultibyte(r rune) bool {
+	return r >= utf8.RuneSelf
 }
 
-// isWSP reports whether c is a WSP (white space).
-// WSP is a space or horizontal tab (RFC5234 Appendix B).
-func isWSP(c byte) bool {
-	return c == ' ' || c == '\t'
+// isWSP reports whether r is a WSP (white space).
+// WSP is a space or horizontal tab (RFC 5234 Appendix B).
+func isWSP(r rune) bool {
+	return r == ' ' || r == '\t'
 }
diff --git a/libgo/go/net/mail/message_test.go b/libgo/go/net/mail/message_test.go
index 4e718e26367..bbbba6b584a 100644
--- a/libgo/go/net/mail/message_test.go
+++ b/libgo/go/net/mail/message_test.go
@@ -92,7 +92,7 @@ func TestDateParsing(t *testing.T) {
 			"Fri, 21 Nov 1997 09:55:06 -0600",
 			time.Date(1997, 11, 21, 9, 55, 6, 0, time.FixedZone("", -6*60*60)),
 		},
-		// RFC5322, Appendix A.6.2
+		// RFC 5322, Appendix A.6.2
 		// Obsolete date.
 		{
 			"21 Nov 97 09:55:06 GMT",
@@ -120,18 +120,24 @@ func TestDateParsing(t *testing.T) {
 }
 
 func TestAddressParsingError(t *testing.T) {
-	const txt = "=?iso-8859-2?Q?Bogl=E1rka_Tak=E1cs?= <unknown@gmail.com>"
-	_, err := ParseAddress(txt)
-	if err == nil || !strings.Contains(err.Error(), "charset not supported") {
-		t.Errorf(`mail.ParseAddress(%q) err: %q, want ".*charset not supported.*"`, txt, err)
+	mustErrTestCases := [...]struct {
+		text        string
+		wantErrText string
+	}{
+		0: {"=?iso-8859-2?Q?Bogl=E1rka_Tak=E1cs?= <unknown@gmail.com>", "charset not supported"},
+		1: {"a@gmail.com b@gmail.com", "expected single address"},
+		2: {string([]byte{0xed, 0xa0, 0x80}) + " <micro@example.net>", "invalid utf-8 in address"},
+		3: {"\"" + string([]byte{0xed, 0xa0, 0x80}) + "\" <half-surrogate@example.com>", "invalid utf-8 in quoted-string"},
+		4: {"\"\\" + string([]byte{0x80}) + "\" <escaped-invalid-unicode@example.net>", "invalid utf-8 in quoted-string"},
+		5: {"\"\x00\" <null@example.net>", "bad character in quoted-string"},
+		6: {"\"\\\x00\" <escaped-null@example.net>", "bad character in quoted-string"},
 	}
-}
 
-func TestAddressParsingErrorUnquotedNonASCII(t *testing.T) {
-	const txt = "µ <micro@example.net>"
-	_, err := ParseAddress(txt)
-	if err == nil || !strings.Contains(err.Error(), "unencoded non-ASCII text in address") {
-		t.Errorf(`mail.ParseAddress(%q) err: %q, want ".*unencoded non-ASCII text in address.*"`, txt, err)
+	for i, tc := range mustErrTestCases {
+		_, err := ParseAddress(tc.text)
+		if err == nil || !strings.Contains(err.Error(), tc.wantErrText) {
+			t.Errorf(`mail.ParseAddress(%q) #%d want %q, got %v`, tc.text, i, tc.wantErrText, err)
+		}
 	}
 }
 
@@ -264,6 +270,46 @@ func TestAddressParsing(t *testing.T) {
 				},
 			},
 		},
+		// RFC 6532 3.2.3, qtext /= UTF8-non-ascii
+		{
+			`"Gø Pher" <gopher@example.com>`,
+			[]*Address{
+				{
+					Name:    `Gø Pher`,
+					Address: "gopher@example.com",
+				},
+			},
+		},
+		// RFC 6532 3.2, atext /= UTF8-non-ascii
+		{
+			`µ <micro@example.com>`,
+			[]*Address{
+				{
+					Name:    `µ`,
+					Address: "micro@example.com",
+				},
+			},
+		},
+		// RFC 6532 3.2.2, local address parts allow UTF-8
+		{
+			`Micro <µ@example.com>`,
+			[]*Address{
+				{
+					Name:    `Micro`,
+					Address: "µ@example.com",
+				},
+			},
+		},
+		// RFC 6532 3.2.4, domains parts allow UTF-8
+		{
+			`Micro <micro@µ.example.com>`,
+			[]*Address{
+				{
+					Name:    `Micro`,
+					Address: "micro@µ.example.com",
+				},
+			},
+		},
 	}
 	for _, test := range tests {
 		if len(test.exp) == 1 {
@@ -515,6 +561,11 @@ func TestAddressString(t *testing.T) {
 			&Address{Name: "world?=", Address: "hello@world.com"},
 			`"world?=" <hello@world.com>`,
 		},
+		{
+			// should q-encode even for invalid utf-8.
+			&Address{Name: string([]byte{0xed, 0xa0, 0x80}), Address: "invalid-utf8@example.net"},
+			"=?utf-8?q?=ED=A0=80?= <invalid-utf8@example.net>",
+		},
 	}
 	for _, test := range tests {
 		s := test.addr.String()
@@ -610,7 +661,6 @@ func TestAddressParsingAndFormatting(t *testing.T) {
 		`< @example.com>`,
 		`<""test""blah""@example.com>`,
 		`<""@0>`,
-		"<\"\t0\"@0>",
 	}
 
 	for _, test := range badTests {
diff --git a/libgo/go/net/main_conf_test.go b/libgo/go/net/main_conf_test.go
new file mode 100644
index 00000000000..9875ceaf1fb
--- /dev/null
+++ b/libgo/go/net/main_conf_test.go
@@ -0,0 +1,38 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !nacl,!plan9,!windows
+
+package net
+
+// forceGoDNS forces the resolver configuration to use the pure Go resolver
+// and returns a fixup function to restore the old settings.
+func forceGoDNS() func() {
+	c := systemConf()
+	oldGo := c.netGo
+	oldCgo := c.netCgo
+	fixup := func() {
+		c.netGo = oldGo
+		c.netCgo = oldCgo
+	}
+	c.netGo = true
+	c.netCgo = false
+	return fixup
+}
+
+// forceCgoDNS forces the resolver configuration to use the cgo resolver
+// and returns a fixup function to restore the old settings.
+// (On non-Unix systems forceCgoDNS returns nil.)
+func forceCgoDNS() func() {
+	c := systemConf()
+	oldGo := c.netGo
+	oldCgo := c.netCgo
+	fixup := func() {
+		c.netGo = oldGo
+		c.netCgo = oldCgo
+	}
+	c.netGo = false
+	c.netCgo = true
+	return fixup
+}
diff --git a/libgo/go/net/non_unix_test.go b/libgo/go/net/main_noconf_test.go
index db3427e7cb4..489477bc97c 100644
--- a/libgo/go/net/non_unix_test.go
+++ b/libgo/go/net/main_noconf_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,7 +8,7 @@ package net
 
 import "runtime"
 
-// See unix_test.go for what these (don't) do.
+// See main_conf_test.go for what these (don't) do.
 func forceGoDNS() func() {
 	switch runtime.GOOS {
 	case "plan9", "windows":
@@ -18,5 +18,5 @@ func forceGoDNS() func() {
 	}
 }
 
-// See unix_test.go for what these (don't) do.
+// See main_conf_test.go for what these (don't) do.
 func forceCgoDNS() func() { return nil }
diff --git a/libgo/go/net/main_plan9_test.go b/libgo/go/net/main_plan9_test.go
index 94501cada9a..2bc5be88be6 100644
--- a/libgo/go/net/main_plan9_test.go
+++ b/libgo/go/net/main_plan9_test.go
@@ -8,6 +8,7 @@ func installTestHooks() {}
 
 func uninstallTestHooks() {}
 
+// forceCloseSockets must be called only from TestMain.
 func forceCloseSockets() {}
 
 func enableSocketConnect() {}
diff --git a/libgo/go/net/main_test.go b/libgo/go/net/main_test.go
index f3f8b1a9002..7573ded93bd 100644
--- a/libgo/go/net/main_test.go
+++ b/libgo/go/net/main_test.go
@@ -26,8 +26,6 @@ var (
 var (
 	testDNSFlood = flag.Bool("dnsflood", false, "whether to test DNS query flooding")
 
-	testExternal = flag.Bool("external", true, "allow use of external networks during long test")
-
 	// If external IPv4 connectivity exists, we can try dialing
 	// non-node/interface local scope IPv4 addresses.
 	// On Windows, Lookup APIs may not return IPv4-related
diff --git a/libgo/go/net/main_unix_test.go b/libgo/go/net/main_unix_test.go
index bfb4cd0065c..0cc129f34dd 100644
--- a/libgo/go/net/main_unix_test.go
+++ b/libgo/go/net/main_unix_test.go
@@ -45,6 +45,7 @@ func uninstallTestHooks() {
 	}
 }
 
+// forceCloseSockets must be called only from TestMain.
 func forceCloseSockets() {
 	for s := range sw.Sockets() {
 		closeFunc(s)
diff --git a/libgo/go/net/main_windows_test.go b/libgo/go/net/main_windows_test.go
index 2d829743ec5..6ea318c2a5f 100644
--- a/libgo/go/net/main_windows_test.go
+++ b/libgo/go/net/main_windows_test.go
@@ -11,6 +11,7 @@ var (
 	origConnect     = connectFunc
 	origConnectEx   = connectExFunc
 	origListen      = listenFunc
+	origAccept      = acceptFunc
 )
 
 func installTestHooks() {
@@ -19,6 +20,7 @@ func installTestHooks() {
 	connectFunc = sw.Connect
 	connectExFunc = sw.ConnectEx
 	listenFunc = sw.Listen
+	acceptFunc = sw.AcceptEx
 }
 
 func uninstallTestHooks() {
@@ -27,8 +29,10 @@ func uninstallTestHooks() {
 	connectFunc = origConnect
 	connectExFunc = origConnectEx
 	listenFunc = origListen
+	acceptFunc = origAccept
 }
 
+// forceCloseSockets must be called only from TestMain.
 func forceCloseSockets() {
 	for s := range sw.Sockets() {
 		closeFunc(s)
diff --git a/libgo/go/net/mockserver_test.go b/libgo/go/net/mockserver_test.go
index dd6f4df3b9c..766de6a815b 100644
--- a/libgo/go/net/mockserver_test.go
+++ b/libgo/go/net/mockserver_test.go
@@ -30,10 +30,20 @@ func testUnixAddr() string {
 
 func newLocalListener(network string) (Listener, error) {
 	switch network {
-	case "tcp", "tcp4", "tcp6":
+	case "tcp":
+		if supportsIPv4 {
+			if ln, err := Listen("tcp4", "127.0.0.1:0"); err == nil {
+				return ln, nil
+			}
+		}
+		if supportsIPv6 {
+			return Listen("tcp6", "[::1]:0")
+		}
+	case "tcp4":
 		if supportsIPv4 {
 			return Listen("tcp4", "127.0.0.1:0")
 		}
+	case "tcp6":
 		if supportsIPv6 {
 			return Listen("tcp6", "[::1]:0")
 		}
@@ -142,13 +152,6 @@ func (dss *dualStackServer) buildup(handler func(*dualStackServer, Listener)) er
 	return nil
 }
 
-func (dss *dualStackServer) putConn(c Conn) error {
-	dss.cmu.Lock()
-	dss.cs = append(dss.cs, c)
-	dss.cmu.Unlock()
-	return nil
-}
-
 func (dss *dualStackServer) teardownNetwork(network string) error {
 	dss.lnmu.Lock()
 	for i := range dss.lns {
@@ -181,28 +184,24 @@ func (dss *dualStackServer) teardown() error {
 	return nil
 }
 
-func newDualStackServer(lns []streamListener) (*dualStackServer, error) {
-	dss := &dualStackServer{lns: lns, port: "0"}
-	for i := range dss.lns {
-		ln, err := Listen(dss.lns[i].network, JoinHostPort(dss.lns[i].address, dss.port))
-		if err != nil {
-			for _, ln := range dss.lns[:i] {
-				ln.Listener.Close()
-			}
-			return nil, err
-		}
-		dss.lns[i].Listener = ln
-		dss.lns[i].done = make(chan bool)
-		if dss.port == "0" {
-			if _, dss.port, err = SplitHostPort(ln.Addr().String()); err != nil {
-				for _, ln := range dss.lns {
-					ln.Listener.Close()
-				}
-				return nil, err
-			}
-		}
+func newDualStackServer() (*dualStackServer, error) {
+	lns, err := newDualStackListener()
+	if err != nil {
+		return nil, err
+	}
+	_, port, err := SplitHostPort(lns[0].Addr().String())
+	if err != nil {
+		lns[0].Close()
+		lns[1].Close()
+		return nil, err
 	}
-	return dss, nil
+	return &dualStackServer{
+		lns: []streamListener{
+			{network: "tcp4", address: lns[0].Addr().String(), Listener: lns[0], done: make(chan bool)},
+			{network: "tcp6", address: lns[1].Addr().String(), Listener: lns[1], done: make(chan bool)},
+		},
+		port: port,
+	}, nil
 }
 
 func transponder(ln Listener, ch chan<- error) {
@@ -225,7 +224,7 @@ func transponder(ln Listener, ch chan<- error) {
 	defer c.Close()
 
 	network := ln.Addr().Network()
-	if c.LocalAddr().Network() != network || c.LocalAddr().Network() != network {
+	if c.LocalAddr().Network() != network || c.RemoteAddr().Network() != network {
 		ch <- fmt.Errorf("got %v->%v; expected %v->%v", c.LocalAddr().Network(), c.RemoteAddr().Network(), network, network)
 		return
 	}
@@ -333,10 +332,18 @@ func timeoutTransmitter(c Conn, d, min, max time.Duration, ch chan<- error) {
 
 func newLocalPacketListener(network string) (PacketConn, error) {
 	switch network {
-	case "udp", "udp4", "udp6":
+	case "udp":
+		if supportsIPv4 {
+			return ListenPacket("udp4", "127.0.0.1:0")
+		}
+		if supportsIPv6 {
+			return ListenPacket("udp6", "[::1]:0")
+		}
+	case "udp4":
 		if supportsIPv4 {
 			return ListenPacket("udp4", "127.0.0.1:0")
 		}
+	case "udp6":
 		if supportsIPv6 {
 			return ListenPacket("udp6", "[::1]:0")
 		}
diff --git a/libgo/go/net/net.go b/libgo/go/net/net.go
index d9d23fae8f6..d6812d1ef05 100644
--- a/libgo/go/net/net.go
+++ b/libgo/go/net/net.go
@@ -14,7 +14,7 @@ the same interfaces and similar Dial and Listen functions.
 
 The Dial function connects to a server:
 
-	conn, err := net.Dial("tcp", "google.com:80")
+	conn, err := net.Dial("tcp", "golang.org:80")
 	if err != nil {
 		// handle error
 	}
@@ -79,6 +79,7 @@ On Windows, the resolver always uses C library functions, such as GetAddrInfo an
 package net
 
 import (
+	"context"
 	"errors"
 	"io"
 	"os"
@@ -297,7 +298,7 @@ func (c *conn) File() (f *os.File, err error) {
 // Multiple goroutines may invoke methods on a PacketConn simultaneously.
 type PacketConn interface {
 	// ReadFrom reads a packet from the connection,
-	// copying the payload into b.  It returns the number of
+	// copying the payload into b. It returns the number of
 	// bytes copied into b and the return address that
 	// was on the packet.
 	// ReadFrom can be made to time out and return
@@ -364,6 +365,9 @@ type Error interface {
 
 // Various errors contained in OpError.
 var (
+	// For connection setup operations.
+	errNoSuitableAddress = errors.New("no suitable address found")
+
 	// For connection setup and write operations.
 	errMissingAddress = errors.New("missing address")
 
@@ -374,6 +378,22 @@ var (
 	ErrWriteToConnected       = errors.New("use of WriteTo with pre-connected connection")
 )
 
+// mapErr maps from the context errors to the historical internal net
+// error values.
+//
+// TODO(bradfitz): get rid of this after adjusting tests and making
+// context.DeadlineExceeded implement net.Error?
+func mapErr(err error) error {
+	switch err {
+	case context.Canceled:
+		return errCanceled
+	case context.DeadlineExceeded:
+		return errTimeout
+	default:
+		return err
+	}
+}
+
 // OpError is the error type usually returned by functions in the net
 // package. It describes the operation, network type, and address of
 // an error.
diff --git a/libgo/go/net/net_test.go b/libgo/go/net/net_test.go
index cd62b4373eb..b2f825daffc 100644
--- a/libgo/go/net/net_test.go
+++ b/libgo/go/net/net_test.go
@@ -6,6 +6,7 @@ package net
 
 import (
 	"io"
+	"net/internal/socktest"
 	"os"
 	"runtime"
 	"testing"
@@ -304,3 +305,112 @@ func TestListenCloseListen(t *testing.T) {
 	}
 	t.Fatalf("failed to listen/close/listen on same address after %d tries", maxTries)
 }
+
+// See golang.org/issue/6163, golang.org/issue/6987.
+func TestAcceptIgnoreAbortedConnRequest(t *testing.T) {
+	switch runtime.GOOS {
+	case "plan9":
+		t.Skipf("%s does not have full support of socktest", runtime.GOOS)
+	}
+
+	syserr := make(chan error)
+	go func() {
+		defer close(syserr)
+		for _, err := range abortedConnRequestErrors {
+			syserr <- err
+		}
+	}()
+	sw.Set(socktest.FilterAccept, func(so *socktest.Status) (socktest.AfterFilter, error) {
+		if err, ok := <-syserr; ok {
+			return nil, err
+		}
+		return nil, nil
+	})
+	defer sw.Set(socktest.FilterAccept, nil)
+
+	operr := make(chan error, 1)
+	handler := func(ls *localServer, ln Listener) {
+		defer close(operr)
+		c, err := ln.Accept()
+		if err != nil {
+			if perr := parseAcceptError(err); perr != nil {
+				operr <- perr
+			}
+			operr <- err
+			return
+		}
+		c.Close()
+	}
+	ls, err := newLocalServer("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ls.teardown()
+	if err := ls.buildup(handler); err != nil {
+		t.Fatal(err)
+	}
+
+	c, err := Dial(ls.Listener.Addr().Network(), ls.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.Close()
+
+	for err := range operr {
+		t.Error(err)
+	}
+}
+
+func TestZeroByteRead(t *testing.T) {
+	for _, network := range []string{"tcp", "unix", "unixpacket"} {
+		if !testableNetwork(network) {
+			t.Logf("skipping %s test", network)
+			continue
+		}
+
+		ln, err := newLocalListener(network)
+		if err != nil {
+			t.Fatal(err)
+		}
+		connc := make(chan Conn, 1)
+		go func() {
+			defer ln.Close()
+			c, err := ln.Accept()
+			if err != nil {
+				t.Error(err)
+			}
+			connc <- c // might be nil
+		}()
+		c, err := Dial(network, ln.Addr().String())
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer c.Close()
+		sc := <-connc
+		if sc == nil {
+			continue
+		}
+		defer sc.Close()
+
+		if runtime.GOOS == "windows" {
+			// A zero byte read on Windows caused a wait for readability first.
+			// Rather than change that behavior, satisfy it in this test.
+			// See Issue 15735.
+			go io.WriteString(sc, "a")
+		}
+
+		n, err := c.Read(nil)
+		if n != 0 || err != nil {
+			t.Errorf("%s: zero byte client read = %v, %v; want 0, nil", network, n, err)
+		}
+
+		if runtime.GOOS == "windows" {
+			// Same as comment above.
+			go io.WriteString(c, "a")
+		}
+		n, err = sc.Read(nil)
+		if n != 0 || err != nil {
+			t.Errorf("%s: zero byte server read = %v, %v; want 0, nil", network, n, err)
+		}
+	}
+}
diff --git a/libgo/go/net/packetconn_test.go b/libgo/go/net/packetconn_test.go
index 7f3ea8a2d0c..7d504890217 100644
--- a/libgo/go/net/packetconn_test.go
+++ b/libgo/go/net/packetconn_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/parse.go b/libgo/go/net/parse.go
index 80836a108c9..2c6b98ad9bc 100644
--- a/libgo/go/net/parse.go
+++ b/libgo/go/net/parse.go
@@ -106,14 +106,14 @@ func splitAtBytes(s string, t string) []string {
 	for i := 0; i < len(s); i++ {
 		if byteIndex(t, s[i]) >= 0 {
 			if last < i {
-				a[n] = string(s[last:i])
+				a[n] = s[last:i]
 				n++
 			}
 			last = i + 1
 		}
 	}
 	if last < len(s) {
-		a[n] = string(s[last:])
+		a[n] = s[last:]
 		n++
 	}
 	return a[0:n]
diff --git a/libgo/go/net/pipe.go b/libgo/go/net/pipe.go
index 5fc830b7408..37e552f54e5 100644
--- a/libgo/go/net/pipe.go
+++ b/libgo/go/net/pipe.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/pipe_test.go b/libgo/go/net/pipe_test.go
index 60c39205932..e3172d882fb 100644
--- a/libgo/go/net/pipe_test.go
+++ b/libgo/go/net/pipe_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/platform_test.go b/libgo/go/net/platform_test.go
index 76c53138cdd..2a14095cc28 100644
--- a/libgo/go/net/platform_test.go
+++ b/libgo/go/net/platform_test.go
@@ -5,6 +5,7 @@
 package net
 
 import (
+	"internal/testenv"
 	"os"
 	"runtime"
 	"strings"
@@ -110,7 +111,7 @@ func testableListenArgs(network, address, client string) bool {
 	}
 
 	// Test wildcard IP addresses.
-	if wildcard && (testing.Short() || !*testExternal) {
+	if wildcard && !testenv.HasExternalNetwork() {
 		return false
 	}
 
diff --git a/libgo/go/net/port.go b/libgo/go/net/port.go
new file mode 100644
index 00000000000..8e1321afa44
--- /dev/null
+++ b/libgo/go/net/port.go
@@ -0,0 +1,62 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+// parsePort parses service as a decimal interger and returns the
+// corresponding value as port. It is the caller's responsibility to
+// parse service as a non-decimal integer when needsLookup is true.
+//
+// Some system resolvers will return a valid port number when given a number
+// over 65536 (see https://github.com/golang/go/issues/11715). Alas, the parser
+// can't bail early on numbers > 65536. Therefore reasonably large/small
+// numbers are parsed in full and rejected if invalid.
+func parsePort(service string) (port int, needsLookup bool) {
+	if service == "" {
+		// Lock in the legacy behavior that an empty string
+		// means port 0. See golang.org/issue/13610.
+		return 0, false
+	}
+	const (
+		max    = uint32(1<<32 - 1)
+		cutoff = uint32(1 << 30)
+	)
+	neg := false
+	if service[0] == '+' {
+		service = service[1:]
+	} else if service[0] == '-' {
+		neg = true
+		service = service[1:]
+	}
+	var n uint32
+	for _, d := range service {
+		if '0' <= d && d <= '9' {
+			d -= '0'
+		} else {
+			return 0, true
+		}
+		if n >= cutoff {
+			n = max
+			break
+		}
+		n *= 10
+		nn := n + uint32(d)
+		if nn < n || nn > max {
+			n = max
+			break
+		}
+		n = nn
+	}
+	if !neg && n >= cutoff {
+		port = int(cutoff - 1)
+	} else if neg && n > cutoff {
+		port = int(cutoff)
+	} else {
+		port = int(n)
+	}
+	if neg {
+		port = -port
+	}
+	return port, false
+}
diff --git a/libgo/go/net/port_test.go b/libgo/go/net/port_test.go
new file mode 100644
index 00000000000..e0bdb4247d3
--- /dev/null
+++ b/libgo/go/net/port_test.go
@@ -0,0 +1,52 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import "testing"
+
+var parsePortTests = []struct {
+	service     string
+	port        int
+	needsLookup bool
+}{
+	{"", 0, false},
+
+	// Decimal number literals
+	{"-1073741825", -1 << 30, false},
+	{"-1073741824", -1 << 30, false},
+	{"-1073741823", -(1<<30 - 1), false},
+	{"-123456789", -123456789, false},
+	{"-1", -1, false},
+	{"-0", 0, false},
+	{"0", 0, false},
+	{"+0", 0, false},
+	{"+1", 1, false},
+	{"65535", 65535, false},
+	{"65536", 65536, false},
+	{"123456789", 123456789, false},
+	{"1073741822", 1<<30 - 2, false},
+	{"1073741823", 1<<30 - 1, false},
+	{"1073741824", 1<<30 - 1, false},
+	{"1073741825", 1<<30 - 1, false},
+
+	// Others
+	{"abc", 0, true},
+	{"9pfs", 0, true},
+	{"123badport", 0, true},
+	{"bad123port", 0, true},
+	{"badport123", 0, true},
+	{"123456789badport", 0, true},
+	{"-2147483649badport", 0, true},
+	{"2147483649badport", 0, true},
+}
+
+func TestParsePort(t *testing.T) {
+	// The following test cases are cribbed from the strconv
+	for _, tt := range parsePortTests {
+		if port, needsLookup := parsePort(tt.service); port != tt.port || needsLookup != tt.needsLookup {
+			t.Errorf("parsePort(%q) = %d, %t; want %d, %t", tt.service, port, needsLookup, tt.port, tt.needsLookup)
+		}
+	}
+}
diff --git a/libgo/go/net/protoconn_test.go b/libgo/go/net/protoconn_test.go
index c6ef23b0e18..23589d3ca87 100644
--- a/libgo/go/net/protoconn_test.go
+++ b/libgo/go/net/protoconn_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/rpc/client.go b/libgo/go/net/rpc/client.go
index d0c4a69214e..862fb1ae0c1 100644
--- a/libgo/go/net/rpc/client.go
+++ b/libgo/go/net/rpc/client.go
@@ -55,7 +55,7 @@ type Client struct {
 // reading of RPC responses for the client side of an RPC session.
 // The client calls WriteRequest to write a request to the connection
 // and calls ReadResponseHeader and ReadResponseBody in pairs
-// to read responses.  The client calls Close when finished with the
+// to read responses. The client calls Close when finished with the
 // connection. ReadResponseBody may be called with a nil
 // argument to force the body of the response to be read and then
 // discarded.
@@ -173,7 +173,7 @@ func (call *Call) done() {
 	case call.Done <- call:
 		// ok
 	default:
-		// We don't want to block here.  It is the caller's responsibility to make
+		// We don't want to block here. It is the caller's responsibility to make
 		// sure the channel has enough buffer space. See comment in Go().
 		if debugLog {
 			log.Println("rpc: discarding Call reply due to insufficient Done chan capacity")
@@ -285,9 +285,9 @@ func (client *Client) Close() error {
 	return client.codec.Close()
 }
 
-// Go invokes the function asynchronously.  It returns the Call structure representing
-// the invocation.  The done channel will signal when the call is complete by returning
-// the same Call object.  If done is nil, Go will allocate a new channel.
+// Go invokes the function asynchronously. It returns the Call structure representing
+// the invocation. The done channel will signal when the call is complete by returning
+// the same Call object. If done is nil, Go will allocate a new channel.
 // If non-nil, done must be buffered or Go will deliberately crash.
 func (client *Client) Go(serviceMethod string, args interface{}, reply interface{}, done chan *Call) *Call {
 	call := new(Call)
@@ -299,7 +299,7 @@ func (client *Client) Go(serviceMethod string, args interface{}, reply interface
 	} else {
 		// If caller passes done != nil, it must arrange that
 		// done has enough buffer for the number of simultaneous
-		// RPCs that will be using that channel.  If the channel
+		// RPCs that will be using that channel. If the channel
 		// is totally unbuffered, it's best not to run at all.
 		if cap(done) == 0 {
 			log.Panic("rpc: done channel is unbuffered")
diff --git a/libgo/go/net/rpc/jsonrpc/all_test.go b/libgo/go/net/rpc/jsonrpc/all_test.go
index a433a365e88..b811d3c0c7c 100644
--- a/libgo/go/net/rpc/jsonrpc/all_test.go
+++ b/libgo/go/net/rpc/jsonrpc/all_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/rpc/jsonrpc/client.go b/libgo/go/net/rpc/jsonrpc/client.go
index 2194f212574..da1b8165fc7 100644
--- a/libgo/go/net/rpc/jsonrpc/client.go
+++ b/libgo/go/net/rpc/jsonrpc/client.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/rpc/jsonrpc/server.go b/libgo/go/net/rpc/jsonrpc/server.go
index e6d37cfa64f..40e4e6f2aa5 100644
--- a/libgo/go/net/rpc/jsonrpc/server.go
+++ b/libgo/go/net/rpc/jsonrpc/server.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -110,7 +110,7 @@ func (c *serverCodec) WriteResponse(r *rpc.Response, x interface{}) error {
 	c.mutex.Unlock()
 
 	if b == nil {
-		// Invalid request so no id.  Use JSON null.
+		// Invalid request so no id. Use JSON null.
 		b = &null
 	}
 	resp := serverResponse{Id: b}
diff --git a/libgo/go/net/rpc/server.go b/libgo/go/net/rpc/server.go
index c4d4479958a..cff32413a34 100644
--- a/libgo/go/net/rpc/server.go
+++ b/libgo/go/net/rpc/server.go
@@ -143,8 +143,8 @@ const (
 	DefaultDebugPath = "/debug/rpc"
 )
 
-// Precompute the reflect type for error.  Can't use error directly
-// because Typeof takes an empty interface value.  This is annoying.
+// Precompute the reflect type for error. Can't use error directly
+// because Typeof takes an empty interface value. This is annoying.
 var typeOfError = reflect.TypeOf((*error)(nil)).Elem()
 
 type methodType struct {
@@ -162,7 +162,7 @@ type service struct {
 	method map[string]*methodType // registered methods
 }
 
-// Request is a header written before every RPC call.  It is used internally
+// Request is a header written before every RPC call. It is used internally
 // but documented here as an aid to debugging, such as when analyzing
 // network traffic.
 type Request struct {
@@ -171,7 +171,7 @@ type Request struct {
 	next          *Request // for free list in Server
 }
 
-// Response is a header written before every RPC return.  It is used internally
+// Response is a header written before every RPC return. It is used internally
 // but documented here as an aid to debugging, such as when analyzing
 // network traffic.
 type Response struct {
@@ -442,7 +442,7 @@ func (c *gobServerCodec) Close() error {
 // ServeConn blocks, serving the connection until the client hangs up.
 // The caller typically invokes ServeConn in a go statement.
 // ServeConn uses the gob wire format (see package gob) on the
-// connection.  To use an alternate codec, use ServeCodec.
+// connection. To use an alternate codec, use ServeCodec.
 func (server *Server) ServeConn(conn io.ReadWriteCloser) {
 	buf := bufio.NewWriter(conn)
 	srv := &gobServerCodec{
@@ -583,7 +583,7 @@ func (server *Server) readRequestHeader(codec ServerCodec) (service *service, mt
 		return
 	}
 
-	// We read the header successfully.  If we see an error now,
+	// We read the header successfully. If we see an error now,
 	// we can still recover and move on to the next request.
 	keepReading = true
 
@@ -638,7 +638,7 @@ func RegisterName(name string, rcvr interface{}) error {
 // RPC responses for the server side of an RPC session.
 // The server calls ReadRequestHeader and ReadRequestBody in pairs
 // to read requests from the connection, and it calls WriteResponse to
-// write a response back.  The server calls Close when finished with the
+// write a response back. The server calls Close when finished with the
 // connection. ReadRequestBody may be called with a nil
 // argument to force the body of the request to be read and discarded.
 type ServerCodec interface {
@@ -654,7 +654,7 @@ type ServerCodec interface {
 // ServeConn blocks, serving the connection until the client hangs up.
 // The caller typically invokes ServeConn in a go statement.
 // ServeConn uses the gob wire format (see package gob) on the
-// connection.  To use an alternate codec, use ServeCodec.
+// connection. To use an alternate codec, use ServeCodec.
 func ServeConn(conn io.ReadWriteCloser) {
 	DefaultServer.ServeConn(conn)
 }
diff --git a/libgo/go/net/rpc/server_test.go b/libgo/go/net/rpc/server_test.go
index 8871c88133c..d04271d99c2 100644
--- a/libgo/go/net/rpc/server_test.go
+++ b/libgo/go/net/rpc/server_test.go
@@ -183,7 +183,7 @@ func testRPC(t *testing.T, addr string) {
 	err = client.Call("Arith.Unknown", args, reply)
 	if err == nil {
 		t.Error("expected error calling unknown service")
-	} else if strings.Index(err.Error(), "method") < 0 {
+	} else if !strings.Contains(err.Error(), "method") {
 		t.Error("expected error about method; got", err)
 	}
 
@@ -226,7 +226,7 @@ func testRPC(t *testing.T, addr string) {
 	err = client.Call("Arith.Add", reply, reply) // args, reply would be the correct thing to use
 	if err == nil {
 		t.Error("expected error calling Arith.Add with wrong arg type")
-	} else if strings.Index(err.Error(), "type") < 0 {
+	} else if !strings.Contains(err.Error(), "type") {
 		t.Error("expected error about type; got", err)
 	}
 
@@ -657,6 +657,9 @@ func benchmarkEndToEnd(dial func() (*Client, error), b *testing.B) {
 }
 
 func benchmarkEndToEndAsync(dial func() (*Client, error), b *testing.B) {
+	if b.N == 0 {
+		return
+	}
 	const MaxConcurrentCalls = 100
 	once.Do(startServer)
 	client, err := dial()
diff --git a/libgo/go/net/sendfile_dragonfly.go b/libgo/go/net/sendfile_dragonfly.go
index a9cf3fe9517..d4b825c3705 100644
--- a/libgo/go/net/sendfile_dragonfly.go
+++ b/libgo/go/net/sendfile_dragonfly.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -53,7 +53,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 	// use the current position of the file -- if you pass it offset 0, it starts
 	// from offset 0. There's no way to tell it "start from current position", so
 	// we have to manage that explicitly.
-	pos, err := f.Seek(0, os.SEEK_CUR)
+	pos, err := f.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return 0, err, false
 	}
@@ -81,7 +81,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 			break
 		}
 		if err1 == syscall.EAGAIN {
-			if err1 = c.pd.WaitWrite(); err1 == nil {
+			if err1 = c.pd.waitWrite(); err1 == nil {
 				continue
 			}
 		}
diff --git a/libgo/go/net/sendfile_freebsd.go b/libgo/go/net/sendfile_freebsd.go
index d0bf6034c18..18cbb27b533 100644
--- a/libgo/go/net/sendfile_freebsd.go
+++ b/libgo/go/net/sendfile_freebsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -53,7 +53,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 	// use the current position of the file -- if you pass it offset 0, it starts
 	// from offset 0. There's no way to tell it "start from current position", so
 	// we have to manage that explicitly.
-	pos, err := f.Seek(0, os.SEEK_CUR)
+	pos, err := f.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return 0, err, false
 	}
@@ -81,7 +81,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 			break
 		}
 		if err1 == syscall.EAGAIN {
-			if err1 = c.pd.WaitWrite(); err1 == nil {
+			if err1 = c.pd.waitWrite(); err1 == nil {
 				continue
 			}
 		}
diff --git a/libgo/go/net/sendfile_linux.go b/libgo/go/net/sendfile_linux.go
index 5ca41c39eb5..7e741f97941 100644
--- a/libgo/go/net/sendfile_linux.go
+++ b/libgo/go/net/sendfile_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -57,7 +57,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 			break
 		}
 		if err1 == syscall.EAGAIN {
-			if err1 = c.pd.WaitWrite(); err1 == nil {
+			if err1 = c.pd.waitWrite(); err1 == nil {
 				continue
 			}
 		}
diff --git a/libgo/go/net/sendfile_solaris.go b/libgo/go/net/sendfile_solaris.go
index f6833813fd0..add70c3147e 100644
--- a/libgo/go/net/sendfile_solaris.go
+++ b/libgo/go/net/sendfile_solaris.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -26,8 +26,6 @@ const maxSendfileSize int = 4 << 20
 //
 // if handled == false, sendFile performed no work.
 func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
-	return // Solaris sendfile is disabled until Issue 13892 is understood and fixed
-
 	// Solaris uses 0 as the "until EOF" value. If you pass in more bytes than the
 	// file contains, it will loop back to the beginning ad nauseam until it's sent
 	// exactly the number of bytes told to. As such, we need to know exactly how many
@@ -59,7 +57,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 	// use the current position of the file -- if you pass it offset 0, it starts
 	// from offset 0. There's no way to tell it "start from current position", so
 	// we have to manage that explicitly.
-	pos, err := f.Seek(0, os.SEEK_CUR)
+	pos, err := f.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return 0, err, false
 	}
@@ -78,6 +76,13 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 		}
 		pos1 := pos
 		n, err1 := syscall.Sendfile(dst, src, &pos1, n)
+		if err1 == syscall.EAGAIN || err1 == syscall.EINTR {
+			// partial write may have occurred
+			if n = int(pos1 - pos); n == 0 {
+				// nothing more to write
+				err1 = nil
+			}
+		}
 		if n > 0 {
 			pos += int64(n)
 			written += int64(n)
@@ -87,7 +92,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 			break
 		}
 		if err1 == syscall.EAGAIN {
-			if err1 = c.pd.WaitWrite(); err1 == nil {
+			if err1 = c.pd.waitWrite(); err1 == nil {
 				continue
 			}
 		}
diff --git a/libgo/go/net/sendfile_stub.go b/libgo/go/net/sendfile_stub.go
index a0760b4e526..905f1d6cef2 100644
--- a/libgo/go/net/sendfile_stub.go
+++ b/libgo/go/net/sendfile_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sendfile_test.go b/libgo/go/net/sendfile_test.go
new file mode 100644
index 00000000000..2255e7c4785
--- /dev/null
+++ b/libgo/go/net/sendfile_test.go
@@ -0,0 +1,90 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package net
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"testing"
+)
+
+const (
+	twain       = "testdata/Mark.Twain-Tom.Sawyer.txt"
+	twainLen    = 387851
+	twainSHA256 = "461eb7cb2d57d293fc680c836464c9125e4382be3596f7d415093ae9db8fcb0e"
+)
+
+func TestSendfile(t *testing.T) {
+	ln, err := newLocalListener("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+
+	errc := make(chan error, 1)
+	go func(ln Listener) {
+		// Wait for a connection.
+		conn, err := ln.Accept()
+		if err != nil {
+			errc <- err
+			close(errc)
+			return
+		}
+
+		go func() {
+			defer close(errc)
+			defer conn.Close()
+
+			f, err := os.Open(twain)
+			if err != nil {
+				errc <- err
+				return
+			}
+			defer f.Close()
+
+			// Return file data using io.Copy, which should use
+			// sendFile if available.
+			sbytes, err := io.Copy(conn, f)
+			if err != nil {
+				errc <- err
+				return
+			}
+
+			if sbytes != twainLen {
+				errc <- fmt.Errorf("sent %d bytes; expected %d", sbytes, twainLen)
+				return
+			}
+		}()
+	}(ln)
+
+	// Connect to listener to retrieve file and verify digest matches
+	// expected.
+	c, err := Dial("tcp", ln.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	h := sha256.New()
+	rbytes, err := io.Copy(h, c)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if rbytes != twainLen {
+		t.Errorf("received %d bytes; expected %d", rbytes, twainLen)
+	}
+
+	if res := hex.EncodeToString(h.Sum(nil)); res != twainSHA256 {
+		t.Error("retrieved data hash did not match")
+	}
+
+	for err := range errc {
+		t.Error(err)
+	}
+}
diff --git a/libgo/go/net/sendfile_windows.go b/libgo/go/net/sendfile_windows.go
index f3f3b54b886..bc0b7fb5b25 100644
--- a/libgo/go/net/sendfile_windows.go
+++ b/libgo/go/net/sendfile_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -18,7 +18,7 @@ import (
 //
 // if handled == false, sendFile performed no work.
 //
-// Note that sendfile for windows does not suppport >2GB file.
+// Note that sendfile for windows does not support >2GB file.
 func sendFile(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
 	var n int64 = 0 // by default, copy until EOF
 
diff --git a/libgo/go/net/smtp/smtp.go b/libgo/go/net/smtp/smtp.go
index 09883503222..9e04dd7c82b 100644
--- a/libgo/go/net/smtp/smtp.go
+++ b/libgo/go/net/smtp/smtp.go
@@ -8,6 +8,11 @@
 //	AUTH      RFC 2554
 //	STARTTLS  RFC 3207
 // Additional extensions may be handled by clients.
+//
+// The smtp package is frozen and not accepting new features.
+// Some external packages provide more functionality. See:
+//
+//   https://godoc.org/?q=smtp
 package smtp
 
 import (
@@ -83,8 +88,8 @@ func (c *Client) hello() error {
 
 // Hello sends a HELO or EHLO to the server as the given host name.
 // Calling this method is only necessary if the client needs control
-// over the host name used.  The client will introduce itself as "localhost"
-// automatically otherwise.  If Hello is called, it must be called before
+// over the host name used. The client will introduce itself as "localhost"
+// automatically otherwise. If Hello is called, it must be called before
 // any of the other methods.
 func (c *Client) Hello(localName string) error {
 	if c.didHello {
@@ -265,7 +270,7 @@ func (d *dataCloser) Close() error {
 
 // Data issues a DATA command to the server and returns a writer that
 // can be used to write the mail headers and body. The caller should
-// close the writer before calling any more methods on c.  A call to
+// close the writer before calling any more methods on c. A call to
 // Data must be preceded by one or more calls to Rcpt.
 func (c *Client) Data() (io.WriteCloser, error) {
 	_, _, err := c.cmd(354, "DATA")
@@ -287,7 +292,7 @@ var testHookStartTLS func(*tls.Config) // nil, except for tests
 //
 // The msg parameter should be an RFC 822-style email with headers
 // first, a blank line, and then the message body. The lines of msg
-// should be CRLF terminated.  The msg headers should usually include
+// should be CRLF terminated. The msg headers should usually include
 // fields such as "From", "To", "Subject", and "Cc".  Sending "Bcc"
 // messages is accomplished by including an email address in the to
 // parameter but not including it in the msg headers.
diff --git a/libgo/go/net/sock_bsd.go b/libgo/go/net/sock_bsd.go
index 6c37109f5e4..4e0e9e01f2c 100644
--- a/libgo/go/net/sock_bsd.go
+++ b/libgo/go/net/sock_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sock_linux.go b/libgo/go/net/sock_linux.go
index cc5ce153b36..e2732c59a57 100644
--- a/libgo/go/net/sock_linux.go
+++ b/libgo/go/net/sock_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sock_plan9.go b/libgo/go/net/sock_plan9.go
index 88d9ed15cf1..9367ad8fa78 100644
--- a/libgo/go/net/sock_plan9.go
+++ b/libgo/go/net/sock_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sock_posix.go b/libgo/go/net/sock_posix.go
index 46767215672..c3af27b596f 100644
--- a/libgo/go/net/sock_posix.go
+++ b/libgo/go/net/sock_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,9 +7,9 @@
 package net
 
 import (
+	"context"
 	"os"
 	"syscall"
-	"time"
 )
 
 // A sockaddr represents a TCP, UDP, IP or Unix network endpoint
@@ -34,7 +34,7 @@ type sockaddr interface {
 
 // socket returns a network file descriptor that is ready for
 // asynchronous I/O using the network poller.
-func socket(net string, family, sotype, proto int, ipv6only bool, laddr, raddr sockaddr, deadline time.Time, cancel <-chan struct{}) (fd *netFD, err error) {
+func socket(ctx context.Context, net string, family, sotype, proto int, ipv6only bool, laddr, raddr sockaddr) (fd *netFD, err error) {
 	s, err := sysSocket(family, sotype, proto)
 	if err != nil {
 		return nil, err
@@ -86,7 +86,7 @@ func socket(net string, family, sotype, proto int, ipv6only bool, laddr, raddr s
 			return fd, nil
 		}
 	}
-	if err := fd.dial(laddr, raddr, deadline, cancel); err != nil {
+	if err := fd.dial(ctx, laddr, raddr); err != nil {
 		fd.Close()
 		return nil, err
 	}
@@ -117,7 +117,7 @@ func (fd *netFD) addrFunc() func(syscall.Sockaddr) Addr {
 	return func(syscall.Sockaddr) Addr { return nil }
 }
 
-func (fd *netFD) dial(laddr, raddr sockaddr, deadline time.Time, cancel <-chan struct{}) error {
+func (fd *netFD) dial(ctx context.Context, laddr, raddr sockaddr) error {
 	var err error
 	var lsa syscall.Sockaddr
 	if laddr != nil {
@@ -134,7 +134,7 @@ func (fd *netFD) dial(laddr, raddr sockaddr, deadline time.Time, cancel <-chan s
 		if rsa, err = raddr.sockaddr(fd.family); err != nil {
 			return err
 		}
-		if err := fd.connect(lsa, rsa, deadline, cancel); err != nil {
+		if err := fd.connect(ctx, lsa, rsa); err != nil {
 			return err
 		}
 		fd.isConnected = true
diff --git a/libgo/go/net/sock_stub.go b/libgo/go/net/sock_stub.go
index ed6b0894893..5ac1e864f7f 100644
--- a/libgo/go/net/sock_stub.go
+++ b/libgo/go/net/sock_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sock_windows.go b/libgo/go/net/sock_windows.go
index 888e70bb8e9..89a3ca42585 100644
--- a/libgo/go/net/sock_windows.go
+++ b/libgo/go/net/sock_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockopt_bsd.go b/libgo/go/net/sockopt_bsd.go
index 52b2a5debc5..734a1093d68 100644
--- a/libgo/go/net/sockopt_bsd.go
+++ b/libgo/go/net/sockopt_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -27,7 +27,7 @@ func setDefaultSockopts(s, family, sotype int, ipv6only bool) error {
 	}
 	if supportsIPv4map && family == syscall.AF_INET6 && sotype != syscall.SOCK_RAW {
 		// Allow both IP versions even if the OS default
-		// is otherwise.  Note that some operating systems
+		// is otherwise. Note that some operating systems
 		// never admit this option.
 		syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, boolint(ipv6only))
 	}
diff --git a/libgo/go/net/sockopt_linux.go b/libgo/go/net/sockopt_linux.go
index 54c20b1409b..0f70b12407b 100644
--- a/libgo/go/net/sockopt_linux.go
+++ b/libgo/go/net/sockopt_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,7 +12,7 @@ import (
 func setDefaultSockopts(s, family, sotype int, ipv6only bool) error {
 	if family == syscall.AF_INET6 && sotype != syscall.SOCK_RAW {
 		// Allow both IP versions even if the OS default
-		// is otherwise.  Note that some operating systems
+		// is otherwise. Note that some operating systems
 		// never admit this option.
 		syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, boolint(ipv6only))
 	}
diff --git a/libgo/go/net/sockopt_plan9.go b/libgo/go/net/sockopt_plan9.go
index 8bc689b6c29..02468cda970 100644
--- a/libgo/go/net/sockopt_plan9.go
+++ b/libgo/go/net/sockopt_plan9.go
@@ -1,9 +1,11 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
+import "syscall"
+
 func setKeepAlive(fd *netFD, keepalive bool) error {
 	if keepalive {
 		_, e := fd.ctl.WriteAt([]byte("keepalive"), 0)
@@ -11,3 +13,7 @@ func setKeepAlive(fd *netFD, keepalive bool) error {
 	}
 	return nil
 }
+
+func setLinger(fd *netFD, sec int) error {
+	return syscall.EPLAN9
+}
diff --git a/libgo/go/net/sockopt_posix.go b/libgo/go/net/sockopt_posix.go
index 1654d1b85e4..cd3d5622894 100644
--- a/libgo/go/net/sockopt_posix.go
+++ b/libgo/go/net/sockopt_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockopt_solaris.go b/libgo/go/net/sockopt_solaris.go
index 54c20b1409b..0f70b12407b 100644
--- a/libgo/go/net/sockopt_solaris.go
+++ b/libgo/go/net/sockopt_solaris.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,7 +12,7 @@ import (
 func setDefaultSockopts(s, family, sotype int, ipv6only bool) error {
 	if family == syscall.AF_INET6 && sotype != syscall.SOCK_RAW {
 		// Allow both IP versions even if the OS default
-		// is otherwise.  Note that some operating systems
+		// is otherwise. Note that some operating systems
 		// never admit this option.
 		syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, boolint(ipv6only))
 	}
diff --git a/libgo/go/net/sockopt_stub.go b/libgo/go/net/sockopt_stub.go
index de5ee0bb63c..7e9e560e059 100644
--- a/libgo/go/net/sockopt_stub.go
+++ b/libgo/go/net/sockopt_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockopt_windows.go b/libgo/go/net/sockopt_windows.go
index cb64a40c695..80174265212 100644
--- a/libgo/go/net/sockopt_windows.go
+++ b/libgo/go/net/sockopt_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,7 +12,7 @@ import (
 func setDefaultSockopts(s syscall.Handle, family, sotype int, ipv6only bool) error {
 	if family == syscall.AF_INET6 && sotype != syscall.SOCK_RAW {
 		// Allow both IP versions even if the OS default
-		// is otherwise.  Note that some operating systems
+		// is otherwise. Note that some operating systems
 		// never admit this option.
 		syscall.SetsockoptInt(s, syscall.IPPROTO_IPV6, syscall.IPV6_V6ONLY, boolint(ipv6only))
 	}
diff --git a/libgo/go/net/sockoptip_bsd.go b/libgo/go/net/sockoptip_bsd.go
index 2199e480d42..b15c6396ba1 100644
--- a/libgo/go/net/sockoptip_bsd.go
+++ b/libgo/go/net/sockoptip_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockoptip_linux.go b/libgo/go/net/sockoptip_linux.go
index a69b778e4d1..c1dcc911c73 100644
--- a/libgo/go/net/sockoptip_linux.go
+++ b/libgo/go/net/sockoptip_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockoptip_posix.go b/libgo/go/net/sockoptip_posix.go
index c2579be9114..d50886003eb 100644
--- a/libgo/go/net/sockoptip_posix.go
+++ b/libgo/go/net/sockoptip_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockoptip_stub.go b/libgo/go/net/sockoptip_stub.go
index 32ec5ddb859..f698687514d 100644
--- a/libgo/go/net/sockoptip_stub.go
+++ b/libgo/go/net/sockoptip_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/sockoptip_windows.go b/libgo/go/net/sockoptip_windows.go
index 7b11f207aaf..916debebc6f 100644
--- a/libgo/go/net/sockoptip_windows.go
+++ b/libgo/go/net/sockoptip_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsock.go b/libgo/go/net/tcpsock.go
index 8765affd462..7cffcc58cbb 100644
--- a/libgo/go/net/tcpsock.go
+++ b/libgo/go/net/tcpsock.go
@@ -1,9 +1,17 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
+import (
+	"context"
+	"io"
+	"os"
+	"syscall"
+	"time"
+)
+
 // TCPAddr represents the address of a TCP end point.
 type TCPAddr struct {
 	IP   IP
@@ -53,9 +61,234 @@ func ResolveTCPAddr(net, addr string) (*TCPAddr, error) {
 	default:
 		return nil, UnknownNetworkError(net)
 	}
-	addrs, err := internetAddrList(net, addr, noDeadline)
+	addrs, err := internetAddrList(context.Background(), net, addr)
 	if err != nil {
 		return nil, err
 	}
 	return addrs.first(isIPv4).(*TCPAddr), nil
 }
+
+// TCPConn is an implementation of the Conn interface for TCP network
+// connections.
+type TCPConn struct {
+	conn
+}
+
+// ReadFrom implements the io.ReaderFrom ReadFrom method.
+func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	n, err := c.readFrom(r)
+	if err != nil && err != io.EOF {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return n, err
+}
+
+// CloseRead shuts down the reading side of the TCP connection.
+// Most callers should just use Close.
+func (c *TCPConn) CloseRead() error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := c.fd.closeRead(); err != nil {
+		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// CloseWrite shuts down the writing side of the TCP connection.
+// Most callers should just use Close.
+func (c *TCPConn) CloseWrite() error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := c.fd.closeWrite(); err != nil {
+		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetLinger sets the behavior of Close on a connection which still
+// has data waiting to be sent or to be acknowledged.
+//
+// If sec < 0 (the default), the operating system finishes sending the
+// data in the background.
+//
+// If sec == 0, the operating system discards any unsent or
+// unacknowledged data.
+//
+// If sec > 0, the data is sent in the background as with sec < 0. On
+// some operating systems after sec seconds have elapsed any remaining
+// unsent data may be discarded.
+func (c *TCPConn) SetLinger(sec int) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setLinger(c.fd, sec); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetKeepAlive sets whether the operating system should send
+// keepalive messages on the connection.
+func (c *TCPConn) SetKeepAlive(keepalive bool) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setKeepAlive(c.fd, keepalive); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetKeepAlivePeriod sets period between keep alives.
+func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setKeepAlivePeriod(c.fd, d); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// SetNoDelay controls whether the operating system should delay
+// packet transmission in hopes of sending fewer packets (Nagle's
+// algorithm).  The default is true (no delay), meaning that data is
+// sent as soon as possible after a Write.
+func (c *TCPConn) SetNoDelay(noDelay bool) error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := setNoDelay(c.fd, noDelay); err != nil {
+		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+func newTCPConn(fd *netFD) *TCPConn {
+	c := &TCPConn{conn{fd}}
+	setNoDelay(c.fd, true)
+	return c
+}
+
+// DialTCP connects to the remote address raddr on the network net,
+// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
+// used as the local address for the connection.
+func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+	switch net {
+	case "tcp", "tcp4", "tcp6":
+	default:
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if raddr == nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+	}
+	c, err := dialTCP(context.Background(), net, laddr, raddr)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
+
+// TCPListener is a TCP network listener. Clients should typically
+// use variables of type Listener instead of assuming TCP.
+type TCPListener struct {
+	fd *netFD
+}
+
+// AcceptTCP accepts the next incoming call and returns the new
+// connection.
+func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	c, err := l.accept()
+	if err != nil {
+		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return c, nil
+}
+
+// Accept implements the Accept method in the Listener interface; it
+// waits for the next call and returns a generic Conn.
+func (l *TCPListener) Accept() (Conn, error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	c, err := l.accept()
+	if err != nil {
+		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return c, nil
+}
+
+// Close stops listening on the TCP address.
+// Already Accepted connections are not closed.
+func (l *TCPListener) Close() error {
+	if !l.ok() {
+		return syscall.EINVAL
+	}
+	if err := l.close(); err != nil {
+		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return nil
+}
+
+// Addr returns the listener's network address, a *TCPAddr.
+// The Addr returned is shared by all invocations of Addr, so
+// do not modify it.
+func (l *TCPListener) Addr() Addr { return l.fd.laddr }
+
+// SetDeadline sets the deadline associated with the listener.
+// A zero time value disables the deadline.
+func (l *TCPListener) SetDeadline(t time.Time) error {
+	if !l.ok() {
+		return syscall.EINVAL
+	}
+	if err := l.fd.setDeadline(t); err != nil {
+		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return nil
+}
+
+// File returns a copy of the underlying os.File, set to blocking
+// mode. It is the caller's responsibility to close f when finished.
+// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
+func (l *TCPListener) File() (f *os.File, err error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	f, err = l.file()
+	if err != nil {
+		return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return
+}
+
+// ListenTCP announces on the TCP address laddr and returns a TCP
+// listener. Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
+// port of 0, ListenTCP will choose an available port. The caller can
+// use the Addr method of TCPListener to retrieve the chosen address.
+func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
+	switch net {
+	case "tcp", "tcp4", "tcp6":
+	default:
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if laddr == nil {
+		laddr = &TCPAddr{}
+	}
+	ln, err := listenTCP(context.Background(), net, laddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
+	}
+	return ln, nil
+}
diff --git a/libgo/go/net/tcpsock_plan9.go b/libgo/go/net/tcpsock_plan9.go
index afccbfe8a74..d2860607f8b 100644
--- a/libgo/go/net/tcpsock_plan9.go
+++ b/libgo/go/net/tcpsock_plan9.go
@@ -1,230 +1,73 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"context"
 	"io"
 	"os"
-	"syscall"
-	"time"
 )
 
-// TCPConn is an implementation of the Conn interface for TCP network
-// connections.
-type TCPConn struct {
-	conn
+func (c *TCPConn) readFrom(r io.Reader) (int64, error) {
+	return genericReadFrom(c, r)
 }
 
-func newTCPConn(fd *netFD) *TCPConn {
-	return &TCPConn{conn{fd}}
-}
-
-// ReadFrom implements the io.ReaderFrom ReadFrom method.
-func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
-	n, err := genericReadFrom(c, r)
-	if err != nil && err != io.EOF {
-		err = &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return n, err
-}
-
-// CloseRead shuts down the reading side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseRead() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeRead()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+func dialTCP(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+	if testHookDialTCP != nil {
+		return testHookDialTCP(ctx, net, laddr, raddr)
 	}
-	return err
-}
-
-// CloseWrite shuts down the writing side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseWrite() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeWrite()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// SetLinger sets the behavior of Close on a connection which still
-// has data waiting to be sent or to be acknowledged.
-//
-// If sec < 0 (the default), the operating system finishes sending the
-// data in the background.
-//
-// If sec == 0, the operating system discards any unsent or
-// unacknowledged data.
-//
-// If sec > 0, the data is sent in the background as with sec < 0. On
-// some operating systems after sec seconds have elapsed any remaining
-// unsent data may be discarded.
-func (c *TCPConn) SetLinger(sec int) error {
-	return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
-}
-
-// SetKeepAlive sets whether the operating system should send
-// keepalive messages on the connection.
-func (c *TCPConn) SetKeepAlive(keepalive bool) error {
-	if !c.ok() {
-		return syscall.EPLAN9
-	}
-	if err := setKeepAlive(c.fd, keepalive); err != nil {
-		return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetKeepAlivePeriod sets period between keep alives.
-func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
-	if !c.ok() {
-		return syscall.EPLAN9
-	}
-	if err := setKeepAlivePeriod(c.fd, d); err != nil {
-		return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetNoDelay controls whether the operating system should delay
-// packet transmission in hopes of sending fewer packets (Nagle's
-// algorithm).  The default is true (no delay), meaning that data is
-// sent as soon as possible after a Write.
-func (c *TCPConn) SetNoDelay(noDelay bool) error {
-	return &OpError{Op: "set", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
-}
-
-// DialTCP connects to the remote address raddr on the network net,
-// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
-// used as the local address for the connection.
-func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
-	return dialTCP(net, laddr, raddr, noDeadline, noCancel)
+	return doDialTCP(ctx, net, laddr, raddr)
 }
 
-func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-chan struct{}) (*TCPConn, error) {
-	if !deadline.IsZero() {
-		panic("net.dialTCP: deadline not implemented on Plan 9")
-	}
-	// TODO(bradfitz,0intro): also use the cancel channel.
+func doDialTCP(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
 	switch net {
 	case "tcp", "tcp4", "tcp6":
 	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+		return nil, UnknownNetworkError(net)
 	}
 	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+		return nil, errMissingAddress
 	}
-	fd, err := dialPlan9(net, laddr, raddr)
+	fd, err := dialPlan9(ctx, net, laddr, raddr)
 	if err != nil {
 		return nil, err
 	}
 	return newTCPConn(fd), nil
 }
 
-// TCPListener is a TCP network listener.  Clients should typically
-// use variables of type Listener instead of assuming TCP.
-type TCPListener struct {
-	fd *netFD
-}
+func (ln *TCPListener) ok() bool { return ln != nil && ln.fd != nil && ln.fd.ctl != nil }
 
-// AcceptTCP accepts the next incoming call and returns the new
-// connection.
-func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return nil, syscall.EINVAL
-	}
-	fd, err := l.fd.acceptPlan9()
+func (ln *TCPListener) accept() (*TCPConn, error) {
+	fd, err := ln.fd.acceptPlan9()
 	if err != nil {
 		return nil, err
 	}
 	return newTCPConn(fd), nil
 }
 
-// Accept implements the Accept method in the Listener interface; it
-// waits for the next call and returns a generic Conn.
-func (l *TCPListener) Accept() (Conn, error) {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return nil, syscall.EINVAL
+func (ln *TCPListener) close() error {
+	if _, err := ln.fd.ctl.WriteString("hangup"); err != nil {
+		ln.fd.ctl.Close()
+		return err
 	}
-	c, err := l.AcceptTCP()
-	if err != nil {
-		return nil, err
-	}
-	return c, nil
-}
-
-// Close stops listening on the TCP address.
-// Already Accepted connections are not closed.
-func (l *TCPListener) Close() error {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return syscall.EINVAL
-	}
-	if _, err := l.fd.ctl.WriteString("hangup"); err != nil {
-		l.fd.ctl.Close()
-		return &OpError{Op: "close", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	err := l.fd.ctl.Close()
-	if err != nil {
-		err = &OpError{Op: "close", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return err
-}
-
-// Addr returns the listener's network address, a *TCPAddr.
-// The Addr returned is shared by all invocations of Addr, so
-// do not modify it.
-func (l *TCPListener) Addr() Addr { return l.fd.laddr }
-
-// SetDeadline sets the deadline associated with the listener.
-// A zero time value disables the deadline.
-func (l *TCPListener) SetDeadline(t time.Time) error {
-	if l == nil || l.fd == nil || l.fd.ctl == nil {
-		return syscall.EINVAL
-	}
-	if err := l.fd.setDeadline(t); err != nil {
-		return &OpError{Op: "set", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
+	if err := ln.fd.ctl.Close(); err != nil {
+		return err
 	}
 	return nil
 }
 
-// File returns a copy of the underlying os.File, set to blocking
-// mode.  It is the caller's responsibility to close f when finished.
-// Closing l does not affect f, and closing f does not affect l.
-//
-// The returned os.File's file descriptor is different from the
-// connection's.  Attempting to change properties of the original
-// using this duplicate may or may not have the desired effect.
-func (l *TCPListener) File() (f *os.File, err error) {
-	f, err = l.dup()
+func (ln *TCPListener) file() (*os.File, error) {
+	f, err := ln.dup()
 	if err != nil {
-		err = &OpError{Op: "file", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: err}
+		return nil, err
 	}
-	return
+	return f, nil
 }
 
-// ListenTCP announces on the TCP address laddr and returns a TCP
-// listener.  Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
-// port of 0, ListenTCP will choose an available port.  The caller can
-// use the Addr method of TCPListener to retrieve the chosen address.
-func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
-	switch net {
-	case "tcp", "tcp4", "tcp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		laddr = &TCPAddr{}
-	}
-	fd, err := listenPlan9(net, laddr)
+func listenTCP(ctx context.Context, network string, laddr *TCPAddr) (*TCPListener, error) {
+	fd, err := listenPlan9(ctx, network, laddr)
 	if err != nil {
 		return nil, err
 	}
diff --git a/libgo/go/net/tcpsock_posix.go b/libgo/go/net/tcpsock_posix.go
index 0e12d543002..c9a8b6808ea 100644
--- a/libgo/go/net/tcpsock_posix.go
+++ b/libgo/go/net/tcpsock_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,10 +7,10 @@
 package net
 
 import (
+	"context"
 	"io"
 	"os"
 	"syscall"
-	"time"
 )
 
 func sockaddrToTCP(sa syscall.Sockaddr) Addr {
@@ -40,151 +40,38 @@ func (a *TCPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, a.Port, a.Zone)
 }
 
-// TCPConn is an implementation of the Conn interface for TCP network
-// connections.
-type TCPConn struct {
-	conn
-}
-
-func newTCPConn(fd *netFD) *TCPConn {
-	c := &TCPConn{conn{fd}}
-	setNoDelay(c.fd, true)
-	return c
-}
-
-// ReadFrom implements the io.ReaderFrom ReadFrom method.
-func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
+func (c *TCPConn) readFrom(r io.Reader) (int64, error) {
 	if n, err, handled := sendFile(c.fd, r); handled {
-		if err != nil && err != io.EOF {
-			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-		}
 		return n, err
 	}
-	n, err := genericReadFrom(c, r)
-	if err != nil && err != io.EOF {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return n, err
-}
-
-// CloseRead shuts down the reading side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseRead() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeRead()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// CloseWrite shuts down the writing side of the TCP connection.
-// Most callers should just use Close.
-func (c *TCPConn) CloseWrite() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeWrite()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
+	return genericReadFrom(c, r)
 }
 
-// SetLinger sets the behavior of Close on a connection which still
-// has data waiting to be sent or to be acknowledged.
-//
-// If sec < 0 (the default), the operating system finishes sending the
-// data in the background.
-//
-// If sec == 0, the operating system discards any unsent or
-// unacknowledged data.
-//
-// If sec > 0, the data is sent in the background as with sec < 0. On
-// some operating systems after sec seconds have elapsed any remaining
-// unsent data may be discarded.
-func (c *TCPConn) SetLinger(sec int) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setLinger(c.fd, sec); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+func dialTCP(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+	if testHookDialTCP != nil {
+		return testHookDialTCP(ctx, net, laddr, raddr)
 	}
-	return nil
+	return doDialTCP(ctx, net, laddr, raddr)
 }
 
-// SetKeepAlive sets whether the operating system should send
-// keepalive messages on the connection.
-func (c *TCPConn) SetKeepAlive(keepalive bool) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setKeepAlive(c.fd, keepalive); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetKeepAlivePeriod sets period between keep alives.
-func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setKeepAlivePeriod(c.fd, d); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// SetNoDelay controls whether the operating system should delay
-// packet transmission in hopes of sending fewer packets (Nagle's
-// algorithm).  The default is true (no delay), meaning that data is
-// sent as soon as possible after a Write.
-func (c *TCPConn) SetNoDelay(noDelay bool) error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	if err := setNoDelay(c.fd, noDelay); err != nil {
-		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return nil
-}
-
-// DialTCP connects to the remote address raddr on the network net,
-// which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is
-// used as the local address for the connection.
-func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
-	switch net {
-	case "tcp", "tcp4", "tcp6":
-	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
-	}
-	return dialTCP(net, laddr, raddr, noDeadline, noCancel)
-}
-
-func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-chan struct{}) (*TCPConn, error) {
-	fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_STREAM, 0, "dial", cancel)
+func doDialTCP(ctx context.Context, net string, laddr, raddr *TCPAddr) (*TCPConn, error) {
+	fd, err := internetSocket(ctx, net, laddr, raddr, syscall.SOCK_STREAM, 0, "dial")
 
 	// TCP has a rarely used mechanism called a 'simultaneous connection' in
 	// which Dial("tcp", addr1, addr2) run on the machine at addr1 can
 	// connect to a simultaneous Dial("tcp", addr2, addr1) run on the machine
-	// at addr2, without either machine executing Listen.  If laddr == nil,
+	// at addr2, without either machine executing Listen. If laddr == nil,
 	// it means we want the kernel to pick an appropriate originating local
-	// address.  Some Linux kernels cycle blindly through a fixed range of
-	// local ports, regardless of destination port.  If a kernel happens to
+	// address. Some Linux kernels cycle blindly through a fixed range of
+	// local ports, regardless of destination port. If a kernel happens to
 	// pick local port 50001 as the source for a Dial("tcp", "", "localhost:50001"),
 	// then the Dial will succeed, having simultaneously connected to itself.
 	// This can only happen when we are letting the kernel pick a port (laddr == nil)
 	// and when there is no listener for the destination address.
-	// It's hard to argue this is anything other than a kernel bug.  If we
+	// It's hard to argue this is anything other than a kernel bug. If we
 	// see this happen, rather than expose the buggy effect to users, we
-	// close the fd and try again.  If it happens twice more, we relent and
-	// use the result.  See also:
+	// close the fd and try again. If it happens twice more, we relent and
+	// use the result. See also:
 	//	https://golang.org/issue/2690
 	//	http://stackoverflow.com/questions/4949858/
 	//
@@ -198,11 +85,11 @@ func dialTCP(net string, laddr, raddr *TCPAddr, deadline time.Time, cancel <-cha
 		if err == nil {
 			fd.Close()
 		}
-		fd, err = internetSocket(net, laddr, raddr, deadline, syscall.SOCK_STREAM, 0, "dial", cancel)
+		fd, err = internetSocket(ctx, net, laddr, raddr, syscall.SOCK_STREAM, 0, "dial")
 	}
 
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newTCPConn(fd), nil
 }
@@ -239,96 +126,32 @@ func spuriousENOTAVAIL(err error) bool {
 	return err == syscall.EADDRNOTAVAIL
 }
 
-// TCPListener is a TCP network listener.  Clients should typically
-// use variables of type Listener instead of assuming TCP.
-type TCPListener struct {
-	fd *netFD
-}
-
-// AcceptTCP accepts the next incoming call and returns the new
-// connection.
-func (l *TCPListener) AcceptTCP() (*TCPConn, error) {
-	if l == nil || l.fd == nil {
-		return nil, syscall.EINVAL
-	}
-	fd, err := l.fd.accept()
-	if err != nil {
-		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return newTCPConn(fd), nil
-}
+func (ln *TCPListener) ok() bool { return ln != nil && ln.fd != nil }
 
-// Accept implements the Accept method in the Listener interface; it
-// waits for the next call and returns a generic Conn.
-func (l *TCPListener) Accept() (Conn, error) {
-	c, err := l.AcceptTCP()
+func (ln *TCPListener) accept() (*TCPConn, error) {
+	fd, err := ln.fd.accept()
 	if err != nil {
 		return nil, err
 	}
-	return c, nil
-}
-
-// Close stops listening on the TCP address.
-// Already Accepted connections are not closed.
-func (l *TCPListener) Close() error {
-	if l == nil || l.fd == nil {
-		return syscall.EINVAL
-	}
-	err := l.fd.Close()
-	if err != nil {
-		err = &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return err
+	return newTCPConn(fd), nil
 }
 
-// Addr returns the listener's network address, a *TCPAddr.
-// The Addr returned is shared by all invocations of Addr, so
-// do not modify it.
-func (l *TCPListener) Addr() Addr { return l.fd.laddr }
-
-// SetDeadline sets the deadline associated with the listener.
-// A zero time value disables the deadline.
-func (l *TCPListener) SetDeadline(t time.Time) error {
-	if l == nil || l.fd == nil {
-		return syscall.EINVAL
-	}
-	if err := l.fd.setDeadline(t); err != nil {
-		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
-	}
-	return nil
+func (ln *TCPListener) close() error {
+	return ln.fd.Close()
 }
 
-// File returns a copy of the underlying os.File, set to blocking
-// mode.  It is the caller's responsibility to close f when finished.
-// Closing l does not affect f, and closing f does not affect l.
-//
-// The returned os.File's file descriptor is different from the
-// connection's.  Attempting to change properties of the original
-// using this duplicate may or may not have the desired effect.
-func (l *TCPListener) File() (f *os.File, err error) {
-	f, err = l.fd.dup()
+func (ln *TCPListener) file() (*os.File, error) {
+	f, err := ln.fd.dup()
 	if err != nil {
-		err = &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+		return nil, err
 	}
-	return
+	return f, nil
 }
 
-// ListenTCP announces on the TCP address laddr and returns a TCP
-// listener.  Net must be "tcp", "tcp4", or "tcp6".  If laddr has a
-// port of 0, ListenTCP will choose an available port.  The caller can
-// use the Addr method of TCPListener to retrieve the chosen address.
-func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) {
-	switch net {
-	case "tcp", "tcp4", "tcp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		laddr = &TCPAddr{}
-	}
-	fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_STREAM, 0, "listen", noCancel)
+func listenTCP(ctx context.Context, network string, laddr *TCPAddr) (*TCPListener, error) {
+	fd, err := internetSocket(ctx, network, laddr, nil, syscall.SOCK_STREAM, 0, "listen")
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	return &TCPListener{fd}, nil
 }
diff --git a/libgo/go/net/tcp_test.go b/libgo/go/net/tcpsock_test.go
index 9da6f6cdd05..a8d93b02642 100644
--- a/libgo/go/net/tcp_test.go
+++ b/libgo/go/net/tcpsock_test.go
@@ -5,6 +5,7 @@
 package net
 
 import (
+	"internal/testenv"
 	"io"
 	"reflect"
 	"runtime"
@@ -345,9 +346,7 @@ var tcpListenerNameTests = []struct {
 }
 
 func TestTCPListenerName(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	for _, tt := range tcpListenerNameTests {
 		ln, err := ListenTCP(tt.net, tt.laddr)
@@ -363,9 +362,8 @@ func TestTCPListenerName(t *testing.T) {
 }
 
 func TestIPv6LinkLocalUnicastTCP(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
+
 	if !supportsIPv6 {
 		t.Skip("IPv6 is not supported")
 	}
@@ -461,7 +459,6 @@ func TestTCPConcurrentAccept(t *testing.T) {
 }
 
 func TestTCPReadWriteAllocs(t *testing.T) {
-	t.Skip("skipping test on gccgo until escape analysis is turned on")
 	switch runtime.GOOS {
 	case "nacl", "windows":
 		// NaCl needs to allocate pseudo file descriptor
@@ -503,7 +500,8 @@ func TestTCPReadWriteAllocs(t *testing.T) {
 			t.Fatal(err)
 		}
 	})
-	if allocs > 0 {
+	// For gccgo changed "> 0" to "> 7".
+	if allocs > 7 {
 		t.Fatalf("got %v; want 0", allocs)
 	}
 }
@@ -589,3 +587,50 @@ func TestTCPStress(t *testing.T) {
 	ln.Close()
 	<-done
 }
+
+func TestTCPSelfConnect(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		// TODO(brainman): do not know why it hangs.
+		t.Skip("known-broken test on windows")
+	}
+
+	ln, err := newLocalListener("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var d Dialer
+	c, err := d.Dial(ln.Addr().Network(), ln.Addr().String())
+	if err != nil {
+		ln.Close()
+		t.Fatal(err)
+	}
+	network := c.LocalAddr().Network()
+	laddr := *c.LocalAddr().(*TCPAddr)
+	c.Close()
+	ln.Close()
+
+	// Try to connect to that address repeatedly.
+	n := 100000
+	if testing.Short() {
+		n = 1000
+	}
+	switch runtime.GOOS {
+	case "darwin", "dragonfly", "freebsd", "netbsd", "openbsd", "plan9", "solaris", "windows":
+		// Non-Linux systems take a long time to figure
+		// out that there is nothing listening on localhost.
+		n = 100
+	}
+	for i := 0; i < n; i++ {
+		d.Timeout = time.Millisecond
+		c, err := d.Dial(network, laddr.String())
+		if err == nil {
+			addr := c.LocalAddr().(*TCPAddr)
+			if addr.Port == laddr.Port || addr.IP.Equal(laddr.IP) {
+				t.Errorf("Dial %v should fail", addr)
+			} else {
+				t.Logf("Dial %v succeeded - possibly racing with other listener", addr)
+			}
+			c.Close()
+		}
+	}
+}
diff --git a/libgo/go/net/tcpsock_unix_test.go b/libgo/go/net/tcpsock_unix_test.go
new file mode 100644
index 00000000000..c07f7d7889b
--- /dev/null
+++ b/libgo/go/net/tcpsock_unix_test.go
@@ -0,0 +1,79 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin
+
+package net
+
+import (
+	"runtime"
+	"sync"
+	"syscall"
+	"testing"
+	"time"
+)
+
+// See golang.org/issue/14548.
+func TestTCPSupriousConnSetupCompletion(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
+
+	ln, err := newLocalListener("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func(ln Listener) {
+		defer wg.Done()
+		for {
+			c, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			wg.Add(1)
+			go func(c Conn) {
+				var b [1]byte
+				c.Read(b[:])
+				c.Close()
+				wg.Done()
+			}(c)
+		}
+	}(ln)
+
+	attempts := int(1e4) // larger is better
+	wg.Add(attempts)
+	throttle := make(chan struct{}, runtime.GOMAXPROCS(-1)*2)
+	for i := 0; i < attempts; i++ {
+		throttle <- struct{}{}
+		go func(i int) {
+			defer func() {
+				<-throttle
+				wg.Done()
+			}()
+			d := Dialer{Timeout: 50 * time.Millisecond}
+			c, err := d.Dial(ln.Addr().Network(), ln.Addr().String())
+			if err != nil {
+				if perr := parseDialError(err); perr != nil {
+					t.Errorf("#%d: %v", i, err)
+				}
+				return
+			}
+			var b [1]byte
+			if _, err := c.Write(b[:]); err != nil {
+				if perr := parseWriteError(err); perr != nil {
+					t.Errorf("#%d: %v", i, err)
+				}
+				if samePlatformError(err, syscall.ENOTCONN) {
+					t.Errorf("#%d: %v", i, err)
+				}
+			}
+			c.Close()
+		}(i)
+	}
+
+	ln.Close()
+	wg.Wait()
+}
diff --git a/libgo/go/net/tcpsockopt_darwin.go b/libgo/go/net/tcpsockopt_darwin.go
index 1f1609088ba..0d1310eaf9e 100644
--- a/libgo/go/net/tcpsockopt_darwin.go
+++ b/libgo/go/net/tcpsockopt_darwin.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_dragonfly.go b/libgo/go/net/tcpsockopt_dragonfly.go
index 0aa213239d1..7cc716bad10 100644
--- a/libgo/go/net/tcpsockopt_dragonfly.go
+++ b/libgo/go/net/tcpsockopt_dragonfly.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_openbsd.go b/libgo/go/net/tcpsockopt_openbsd.go
index 041e1786a92..10e1bef3e5a 100644
--- a/libgo/go/net/tcpsockopt_openbsd.go
+++ b/libgo/go/net/tcpsockopt_openbsd.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_plan9.go b/libgo/go/net/tcpsockopt_plan9.go
index 157282abd34..fb568718573 100644
--- a/libgo/go/net/tcpsockopt_plan9.go
+++ b/libgo/go/net/tcpsockopt_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,9 +7,14 @@
 package net
 
 import (
+	"syscall"
 	"time"
 )
 
+func setNoDelay(fd *netFD, noDelay bool) error {
+	return syscall.EPLAN9
+}
+
 // Set keep alive period.
 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
 	cmd := "keepalive " + itoa(int(d/time.Millisecond))
diff --git a/libgo/go/net/tcpsockopt_posix.go b/libgo/go/net/tcpsockopt_posix.go
index 0abf3f97f6b..805b56b5c76 100644
--- a/libgo/go/net/tcpsockopt_posix.go
+++ b/libgo/go/net/tcpsockopt_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_solaris.go b/libgo/go/net/tcpsockopt_solaris.go
index eaab6b6787b..347c17d7e27 100644
--- a/libgo/go/net/tcpsockopt_solaris.go
+++ b/libgo/go/net/tcpsockopt_solaris.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors. All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_stub.go b/libgo/go/net/tcpsockopt_stub.go
index b413a764d82..19c83e6a5fa 100644
--- a/libgo/go/net/tcpsockopt_stub.go
+++ b/libgo/go/net/tcpsockopt_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_unix.go b/libgo/go/net/tcpsockopt_unix.go
index c8970d1b574..8d44fb20954 100644
--- a/libgo/go/net/tcpsockopt_unix.go
+++ b/libgo/go/net/tcpsockopt_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/tcpsockopt_windows.go b/libgo/go/net/tcpsockopt_windows.go
index ae2d7c8f182..45a4dca5257 100644
--- a/libgo/go/net/tcpsockopt_windows.go
+++ b/libgo/go/net/tcpsockopt_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/testdata/Mark.Twain-Tom.Sawyer.txt b/libgo/go/net/testdata/Mark.Twain-Tom.Sawyer.txt
new file mode 100644
index 00000000000..c9106fd522c
--- /dev/null
+++ b/libgo/go/net/testdata/Mark.Twain-Tom.Sawyer.txt
@@ -0,0 +1,8465 @@
+Produced by David Widger. The previous edition was updated by Jose
+Menendez.
+
+
+
+
+
+                   THE ADVENTURES OF TOM SAWYER
+                                BY
+                            MARK TWAIN
+                     (Samuel Langhorne Clemens)
+
+
+
+
+                           P R E F A C E
+
+MOST of the adventures recorded in this book really occurred; one or
+two were experiences of my own, the rest those of boys who were
+schoolmates of mine. Huck Finn is drawn from life; Tom Sawyer also, but
+not from an individual--he is a combination of the characteristics of
+three boys whom I knew, and therefore belongs to the composite order of
+architecture.
+
+The odd superstitions touched upon were all prevalent among children
+and slaves in the West at the period of this story--that is to say,
+thirty or forty years ago.
+
+Although my book is intended mainly for the entertainment of boys and
+girls, I hope it will not be shunned by men and women on that account,
+for part of my plan has been to try to pleasantly remind adults of what
+they once were themselves, and of how they felt and thought and talked,
+and what queer enterprises they sometimes engaged in.
+
+                                                            THE AUTHOR.
+
+HARTFORD, 1876.
+
+
+
+                          T O M   S A W Y E R
+
+
+
+CHAPTER I
+
+"TOM!"
+
+No answer.
+
+"TOM!"
+
+No answer.
+
+"What's gone with that boy,  I wonder? You TOM!"
+
+No answer.
+
+The old lady pulled her spectacles down and looked over them about the
+room; then she put them up and looked out under them. She seldom or
+never looked THROUGH them for so small a thing as a boy; they were her
+state pair, the pride of her heart, and were built for "style," not
+service--she could have seen through a pair of stove-lids just as well.
+She looked perplexed for a moment, and then said, not fiercely, but
+still loud enough for the furniture to hear:
+
+"Well, I lay if I get hold of you I'll--"
+
+She did not finish, for by this time she was bending down and punching
+under the bed with the broom, and so she needed breath to punctuate the
+punches with. She resurrected nothing but the cat.
+
+"I never did see the beat of that boy!"
+
+She went to the open door and stood in it and looked out among the
+tomato vines and "jimpson" weeds that constituted the garden. No Tom.
+So she lifted up her voice at an angle calculated for distance and
+shouted:
+
+"Y-o-u-u TOM!"
+
+There was a slight noise behind her and she turned just in time to
+seize a small boy by the slack of his roundabout and arrest his flight.
+
+"There! I might 'a' thought of that closet. What you been doing in
+there?"
+
+"Nothing."
+
+"Nothing! Look at your hands. And look at your mouth. What IS that
+truck?"
+
+"I don't know, aunt."
+
+"Well, I know. It's jam--that's what it is. Forty times I've said if
+you didn't let that jam alone I'd skin you. Hand me that switch."
+
+The switch hovered in the air--the peril was desperate--
+
+"My! Look behind you, aunt!"
+
+The old lady whirled round, and snatched her skirts out of danger. The
+lad fled on the instant, scrambled up the high board-fence, and
+disappeared over it.
+
+His aunt Polly stood surprised a moment, and then broke into a gentle
+laugh.
+
+"Hang the boy, can't I never learn anything? Ain't he played me tricks
+enough like that for me to be looking out for him by this time? But old
+fools is the biggest fools there is. Can't learn an old dog new tricks,
+as the saying is. But my goodness, he never plays them alike, two days,
+and how is a body to know what's coming? He 'pears to know just how
+long he can torment me before I get my dander up, and he knows if he
+can make out to put me off for a minute or make me laugh, it's all down
+again and I can't hit him a lick. I ain't doing my duty by that boy,
+and that's the Lord's truth, goodness knows. Spare the rod and spile
+the child, as the Good Book says. I'm a laying up sin and suffering for
+us both, I know. He's full of the Old Scratch, but laws-a-me! he's my
+own dead sister's boy, poor thing, and I ain't got the heart to lash
+him, somehow. Every time I let him off, my conscience does hurt me so,
+and every time I hit him my old heart most breaks. Well-a-well, man
+that is born of woman is of few days and full of trouble, as the
+Scripture says, and I reckon it's so. He'll play hookey this evening, *
+and [* Southwestern for "afternoon"] I'll just be obleeged to make him
+work, to-morrow, to punish him. It's mighty hard to make him work
+Saturdays, when all the boys is having holiday, but he hates work more
+than he hates anything else, and I've GOT to do some of my duty by him,
+or I'll be the ruination of the child."
+
+Tom did play hookey, and he had a very good time. He got back home
+barely in season to help Jim, the small colored boy, saw next-day's
+wood and split the kindlings before supper--at least he was there in
+time to tell his adventures to Jim while Jim did three-fourths of the
+work. Tom's younger brother (or rather half-brother) Sid was already
+through with his part of the work (picking up chips), for he was a
+quiet boy, and had no adventurous, troublesome ways.
+
+While Tom was eating his supper, and stealing sugar as opportunity
+offered, Aunt Polly asked him questions that were full of guile, and
+very deep--for she wanted to trap him into damaging revealments. Like
+many other simple-hearted souls, it was her pet vanity to believe she
+was endowed with a talent for dark and mysterious diplomacy, and she
+loved to contemplate her most transparent devices as marvels of low
+cunning. Said she:
+
+"Tom, it was middling warm in school, warn't it?"
+
+"Yes'm."
+
+"Powerful warm, warn't it?"
+
+"Yes'm."
+
+"Didn't you want to go in a-swimming, Tom?"
+
+A bit of a scare shot through Tom--a touch of uncomfortable suspicion.
+He searched Aunt Polly's face, but it told him nothing. So he said:
+
+"No'm--well, not very much."
+
+The old lady reached out her hand and felt Tom's shirt, and said:
+
+"But you ain't too warm now, though." And it flattered her to reflect
+that she had discovered that the shirt was dry without anybody knowing
+that that was what she had in her mind. But in spite of her, Tom knew
+where the wind lay, now. So he forestalled what might be the next move:
+
+"Some of us pumped on our heads--mine's damp yet. See?"
+
+Aunt Polly was vexed to think she had overlooked that bit of
+circumstantial evidence, and missed a trick. Then she had a new
+inspiration:
+
+"Tom, you didn't have to undo your shirt collar where I sewed it, to
+pump on your head, did you? Unbutton your jacket!"
+
+The trouble vanished out of Tom's face. He opened his jacket. His
+shirt collar was securely sewed.
+
+"Bother! Well, go 'long with you. I'd made sure you'd played hookey
+and been a-swimming. But I forgive ye, Tom. I reckon you're a kind of a
+singed cat, as the saying is--better'n you look. THIS time."
+
+She was half sorry her sagacity had miscarried, and half glad that Tom
+had stumbled into obedient conduct for once.
+
+But Sidney said:
+
+"Well, now, if I didn't think you sewed his collar with white thread,
+but it's black."
+
+"Why, I did sew it with white! Tom!"
+
+But Tom did not wait for the rest. As he went out at the door he said:
+
+"Siddy, I'll lick you for that."
+
+In a safe place Tom examined two large needles which were thrust into
+the lapels of his jacket, and had thread bound about them--one needle
+carried white thread and the other black. He said:
+
+"She'd never noticed if it hadn't been for Sid. Confound it! sometimes
+she sews it with white, and sometimes she sews it with black. I wish to
+geeminy she'd stick to one or t'other--I can't keep the run of 'em. But
+I bet you I'll lam Sid for that. I'll learn him!"
+
+He was not the Model Boy of the village. He knew the model boy very
+well though--and loathed him.
+
+Within two minutes, or even less, he had forgotten all his troubles.
+Not because his troubles were one whit less heavy and bitter to him
+than a man's are to a man, but because a new and powerful interest bore
+them down and drove them out of his mind for the time--just as men's
+misfortunes are forgotten in the excitement of new enterprises. This
+new interest was a valued novelty in whistling, which he had just
+acquired from a negro, and he was suffering to practise it undisturbed.
+It consisted in a peculiar bird-like turn, a sort of liquid warble,
+produced by touching the tongue to the roof of the mouth at short
+intervals in the midst of the music--the reader probably remembers how
+to do it, if he has ever been a boy. Diligence and attention soon gave
+him the knack of it, and he strode down the street with his mouth full
+of harmony and his soul full of gratitude. He felt much as an
+astronomer feels who has discovered a new planet--no doubt, as far as
+strong, deep, unalloyed pleasure is concerned, the advantage was with
+the boy, not the astronomer.
+
+The summer evenings were long. It was not dark, yet. Presently Tom
+checked his whistle. A stranger was before him--a boy a shade larger
+than himself. A new-comer of any age or either sex was an impressive
+curiosity in the poor little shabby village of St. Petersburg. This boy
+was well dressed, too--well dressed on a week-day. This was simply
+astounding. His cap was a dainty thing, his close-buttoned blue cloth
+roundabout was new and natty, and so were his pantaloons. He had shoes
+on--and it was only Friday. He even wore a necktie, a bright bit of
+ribbon. He had a citified air about him that ate into Tom's vitals. The
+more Tom stared at the splendid marvel, the higher he turned up his
+nose at his finery and the shabbier and shabbier his own outfit seemed
+to him to grow. Neither boy spoke. If one moved, the other moved--but
+only sidewise, in a circle; they kept face to face and eye to eye all
+the time. Finally Tom said:
+
+"I can lick you!"
+
+"I'd like to see you try it."
+
+"Well, I can do it."
+
+"No you can't, either."
+
+"Yes I can."
+
+"No you can't."
+
+"I can."
+
+"You can't."
+
+"Can!"
+
+"Can't!"
+
+An uncomfortable pause. Then Tom said:
+
+"What's your name?"
+
+"'Tisn't any of your business, maybe."
+
+"Well I 'low I'll MAKE it my business."
+
+"Well why don't you?"
+
+"If you say much, I will."
+
+"Much--much--MUCH. There now."
+
+"Oh, you think you're mighty smart, DON'T you? I could lick you with
+one hand tied behind me, if I wanted to."
+
+"Well why don't you DO it? You SAY you can do it."
+
+"Well I WILL, if you fool with me."
+
+"Oh yes--I've seen whole families in the same fix."
+
+"Smarty! You think you're SOME, now, DON'T you? Oh, what a hat!"
+
+"You can lump that hat if you don't like it. I dare you to knock it
+off--and anybody that'll take a dare will suck eggs."
+
+"You're a liar!"
+
+"You're another."
+
+"You're a fighting liar and dasn't take it up."
+
+"Aw--take a walk!"
+
+"Say--if you give me much more of your sass I'll take and bounce a
+rock off'n your head."
+
+"Oh, of COURSE you will."
+
+"Well I WILL."
+
+"Well why don't you DO it then? What do you keep SAYING you will for?
+Why don't you DO it? It's because you're afraid."
+
+"I AIN'T afraid."
+
+"You are."
+
+"I ain't."
+
+"You are."
+
+Another pause, and more eying and sidling around each other. Presently
+they were shoulder to shoulder. Tom said:
+
+"Get away from here!"
+
+"Go away yourself!"
+
+"I won't."
+
+"I won't either."
+
+So they stood, each with a foot placed at an angle as a brace, and
+both shoving with might and main, and glowering at each other with
+hate. But neither could get an advantage. After struggling till both
+were hot and flushed, each relaxed his strain with watchful caution,
+and Tom said:
+
+"You're a coward and a pup. I'll tell my big brother on you, and he
+can thrash you with his little finger, and I'll make him do it, too."
+
+"What do I care for your big brother? I've got a brother that's bigger
+than he is--and what's more, he can throw him over that fence, too."
+[Both brothers were imaginary.]
+
+"That's a lie."
+
+"YOUR saying so don't make it so."
+
+Tom drew a line in the dust with his big toe, and said:
+
+"I dare you to step over that, and I'll lick you till you can't stand
+up. Anybody that'll take a dare will steal sheep."
+
+The new boy stepped over promptly, and said:
+
+"Now you said you'd do it, now let's see you do it."
+
+"Don't you crowd me now; you better look out."
+
+"Well, you SAID you'd do it--why don't you do it?"
+
+"By jingo! for two cents I WILL do it."
+
+The new boy took two broad coppers out of his pocket and held them out
+with derision. Tom struck them to the ground. In an instant both boys
+were rolling and tumbling in the dirt, gripped together like cats; and
+for the space of a minute they tugged and tore at each other's hair and
+clothes, punched and scratched each other's nose, and covered
+themselves with dust and glory. Presently the confusion took form, and
+through the fog of battle Tom appeared, seated astride the new boy, and
+pounding him with his fists. "Holler 'nuff!" said he.
+
+The boy only struggled to free himself. He was crying--mainly from rage.
+
+"Holler 'nuff!"--and the pounding went on.
+
+At last the stranger got out a smothered "'Nuff!" and Tom let him up
+and said:
+
+"Now that'll learn you. Better look out who you're fooling with next
+time."
+
+The new boy went off brushing the dust from his clothes, sobbing,
+snuffling, and occasionally looking back and shaking his head and
+threatening what he would do to Tom the "next time he caught him out."
+To which Tom responded with jeers, and started off in high feather, and
+as soon as his back was turned the new boy snatched up a stone, threw
+it and hit him between the shoulders and then turned tail and ran like
+an antelope. Tom chased the traitor home, and thus found out where he
+lived. He then held a position at the gate for some time, daring the
+enemy to come outside, but the enemy only made faces at him through the
+window and declined. At last the enemy's mother appeared, and called
+Tom a bad, vicious, vulgar child, and ordered him away. So he went
+away; but he said he "'lowed" to "lay" for that boy.
+
+He got home pretty late that night, and when he climbed cautiously in
+at the window, he uncovered an ambuscade, in the person of his aunt;
+and when she saw the state his clothes were in her resolution to turn
+his Saturday holiday into captivity at hard labor became adamantine in
+its firmness.
+
+
+
+CHAPTER II
+
+SATURDAY morning was come, and all the summer world was bright and
+fresh, and brimming with life. There was a song in every heart; and if
+the heart was young the music issued at the lips. There was cheer in
+every face and a spring in every step. The locust-trees were in bloom
+and the fragrance of the blossoms filled the air. Cardiff Hill, beyond
+the village and above it, was green with vegetation and it lay just far
+enough away to seem a Delectable Land, dreamy, reposeful, and inviting.
+
+Tom appeared on the sidewalk with a bucket of whitewash and a
+long-handled brush. He surveyed the fence, and all gladness left him and
+a deep melancholy settled down upon his spirit. Thirty yards of board
+fence nine feet high. Life to him seemed hollow, and existence but a
+burden. Sighing, he dipped his brush and passed it along the topmost
+plank; repeated the operation; did it again; compared the insignificant
+whitewashed streak with the far-reaching continent of unwhitewashed
+fence, and sat down on a tree-box discouraged. Jim came skipping out at
+the gate with a tin pail, and singing Buffalo Gals. Bringing water from
+the town pump had always been hateful work in Tom's eyes, before, but
+now it did not strike him so. He remembered that there was company at
+the pump. White, mulatto, and negro boys and girls were always there
+waiting their turns, resting, trading playthings, quarrelling,
+fighting, skylarking. And he remembered that although the pump was only
+a hundred and fifty yards off, Jim never got back with a bucket of
+water under an hour--and even then somebody generally had to go after
+him. Tom said:
+
+"Say, Jim, I'll fetch the water if you'll whitewash some."
+
+Jim shook his head and said:
+
+"Can't, Mars Tom. Ole missis, she tole me I got to go an' git dis
+water an' not stop foolin' roun' wid anybody. She say she spec' Mars
+Tom gwine to ax me to whitewash, an' so she tole me go 'long an' 'tend
+to my own business--she 'lowed SHE'D 'tend to de whitewashin'."
+
+"Oh, never you mind what she said, Jim. That's the way she always
+talks. Gimme the bucket--I won't be gone only a a minute. SHE won't
+ever know."
+
+"Oh, I dasn't, Mars Tom. Ole missis she'd take an' tar de head off'n
+me. 'Deed she would."
+
+"SHE! She never licks anybody--whacks 'em over the head with her
+thimble--and who cares for that, I'd like to know. She talks awful, but
+talk don't hurt--anyways it don't if she don't cry. Jim, I'll give you
+a marvel. I'll give you a white alley!"
+
+Jim began to waver.
+
+"White alley, Jim! And it's a bully taw."
+
+"My! Dat's a mighty gay marvel, I tell you! But Mars Tom I's powerful
+'fraid ole missis--"
+
+"And besides, if you will I'll show you my sore toe."
+
+Jim was only human--this attraction was too much for him. He put down
+his pail, took the white alley, and bent over the toe with absorbing
+interest while the bandage was being unwound. In another moment he was
+flying down the street with his pail and a tingling rear, Tom was
+whitewashing with vigor, and Aunt Polly was retiring from the field
+with a slipper in her hand and triumph in her eye.
+
+But Tom's energy did not last. He began to think of the fun he had
+planned for this day, and his sorrows multiplied. Soon the free boys
+would come tripping along on all sorts of delicious expeditions, and
+they would make a world of fun of him for having to work--the very
+thought of it burnt him like fire. He got out his worldly wealth and
+examined it--bits of toys, marbles, and trash; enough to buy an
+exchange of WORK, maybe, but not half enough to buy so much as half an
+hour of pure freedom. So he returned his straitened means to his
+pocket, and gave up the idea of trying to buy the boys. At this dark
+and hopeless moment an inspiration burst upon him! Nothing less than a
+great, magnificent inspiration.
+
+He took up his brush and went tranquilly to work. Ben Rogers hove in
+sight presently--the very boy, of all boys, whose ridicule he had been
+dreading. Ben's gait was the hop-skip-and-jump--proof enough that his
+heart was light and his anticipations high. He was eating an apple, and
+giving a long, melodious whoop, at intervals, followed by a deep-toned
+ding-dong-dong, ding-dong-dong, for he was personating a steamboat. As
+he drew near, he slackened speed, took the middle of the street, leaned
+far over to starboard and rounded to ponderously and with laborious
+pomp and circumstance--for he was personating the Big Missouri, and
+considered himself to be drawing nine feet of water. He was boat and
+captain and engine-bells combined, so he had to imagine himself
+standing on his own hurricane-deck giving the orders and executing them:
+
+"Stop her, sir! Ting-a-ling-ling!" The headway ran almost out, and he
+drew up slowly toward the sidewalk.
+
+"Ship up to back! Ting-a-ling-ling!" His arms straightened and
+stiffened down his sides.
+
+"Set her back on the stabboard! Ting-a-ling-ling! Chow! ch-chow-wow!
+Chow!" His right hand, meantime, describing stately circles--for it was
+representing a forty-foot wheel.
+
+"Let her go back on the labboard! Ting-a-lingling! Chow-ch-chow-chow!"
+The left hand began to describe circles.
+
+"Stop the stabboard! Ting-a-ling-ling! Stop the labboard! Come ahead
+on the stabboard! Stop her! Let your outside turn over slow!
+Ting-a-ling-ling! Chow-ow-ow! Get out that head-line! LIVELY now!
+Come--out with your spring-line--what're you about there! Take a turn
+round that stump with the bight of it! Stand by that stage, now--let her
+go! Done with the engines, sir! Ting-a-ling-ling! SH'T! S'H'T! SH'T!"
+(trying the gauge-cocks).
+
+Tom went on whitewashing--paid no attention to the steamboat. Ben
+stared a moment and then said: "Hi-YI! YOU'RE up a stump, ain't you!"
+
+No answer. Tom surveyed his last touch with the eye of an artist, then
+he gave his brush another gentle sweep and surveyed the result, as
+before. Ben ranged up alongside of him. Tom's mouth watered for the
+apple, but he stuck to his work. Ben said:
+
+"Hello, old chap, you got to work, hey?"
+
+Tom wheeled suddenly and said:
+
+"Why, it's you, Ben! I warn't noticing."
+
+"Say--I'm going in a-swimming, I am. Don't you wish you could? But of
+course you'd druther WORK--wouldn't you? Course you would!"
+
+Tom contemplated the boy a bit, and said:
+
+"What do you call work?"
+
+"Why, ain't THAT work?"
+
+Tom resumed his whitewashing, and answered carelessly:
+
+"Well, maybe it is, and maybe it ain't. All I know, is, it suits Tom
+Sawyer."
+
+"Oh come, now, you don't mean to let on that you LIKE it?"
+
+The brush continued to move.
+
+"Like it? Well, I don't see why I oughtn't to like it. Does a boy get
+a chance to whitewash a fence every day?"
+
+That put the thing in a new light. Ben stopped nibbling his apple. Tom
+swept his brush daintily back and forth--stepped back to note the
+effect--added a touch here and there--criticised the effect again--Ben
+watching every move and getting more and more interested, more and more
+absorbed. Presently he said:
+
+"Say, Tom, let ME whitewash a little."
+
+Tom considered, was about to consent; but he altered his mind:
+
+"No--no--I reckon it wouldn't hardly do, Ben. You see, Aunt Polly's
+awful particular about this fence--right here on the street, you know
+--but if it was the back fence I wouldn't mind and SHE wouldn't. Yes,
+she's awful particular about this fence; it's got to be done very
+careful; I reckon there ain't one boy in a thousand, maybe two
+thousand, that can do it the way it's got to be done."
+
+"No--is that so? Oh come, now--lemme just try. Only just a little--I'd
+let YOU, if you was me, Tom."
+
+"Ben, I'd like to, honest injun; but Aunt Polly--well, Jim wanted to
+do it, but she wouldn't let him; Sid wanted to do it, and she wouldn't
+let Sid. Now don't you see how I'm fixed? If you was to tackle this
+fence and anything was to happen to it--"
+
+"Oh, shucks, I'll be just as careful. Now lemme try. Say--I'll give
+you the core of my apple."
+
+"Well, here--No, Ben, now don't. I'm afeard--"
+
+"I'll give you ALL of it!"
+
+Tom gave up the brush with reluctance in his face, but alacrity in his
+heart. And while the late steamer Big Missouri worked and sweated in
+the sun, the retired artist sat on a barrel in the shade close by,
+dangled his legs, munched his apple, and planned the slaughter of more
+innocents. There was no lack of material; boys happened along every
+little while; they came to jeer, but remained to whitewash. By the time
+Ben was fagged out, Tom had traded the next chance to Billy Fisher for
+a kite, in good repair; and when he played out, Johnny Miller bought in
+for a dead rat and a string to swing it with--and so on, and so on,
+hour after hour. And when the middle of the afternoon came, from being
+a poor poverty-stricken boy in the morning, Tom was literally rolling
+in wealth. He had besides the things before mentioned, twelve marbles,
+part of a jews-harp, a piece of blue bottle-glass to look through, a
+spool cannon, a key that wouldn't unlock anything, a fragment of chalk,
+a glass stopper of a decanter, a tin soldier, a couple of tadpoles, six
+fire-crackers, a kitten with only one eye, a brass doorknob, a
+dog-collar--but no dog--the handle of a knife, four pieces of
+orange-peel, and a dilapidated old window sash.
+
+He had had a nice, good, idle time all the while--plenty of company
+--and the fence had three coats of whitewash on it! If he hadn't run out
+of whitewash he would have bankrupted every boy in the village.
+
+Tom said to himself that it was not such a hollow world, after all. He
+had discovered a great law of human action, without knowing it--namely,
+that in order to make a man or a boy covet a thing, it is only
+necessary to make the thing difficult to attain. If he had been a great
+and wise philosopher, like the writer of this book, he would now have
+comprehended that Work consists of whatever a body is OBLIGED to do,
+and that Play consists of whatever a body is not obliged to do. And
+this would help him to understand why constructing artificial flowers
+or performing on a tread-mill is work, while rolling ten-pins or
+climbing Mont Blanc is only amusement. There are wealthy gentlemen in
+England who drive four-horse passenger-coaches twenty or thirty miles
+on a daily line, in the summer, because the privilege costs them
+considerable money; but if they were offered wages for the service,
+that would turn it into work and then they would resign.
+
+The boy mused awhile over the substantial change which had taken place
+in his worldly circumstances, and then wended toward headquarters to
+report.
+
+
+
+CHAPTER III
+
+TOM presented himself before Aunt Polly, who was sitting by an open
+window in a pleasant rearward apartment, which was bedroom,
+breakfast-room, dining-room, and library, combined. The balmy summer
+air, the restful quiet, the odor of the flowers, and the drowsing murmur
+of the bees had had their effect, and she was nodding over her knitting
+--for she had no company but the cat, and it was asleep in her lap. Her
+spectacles were propped up on her gray head for safety. She had thought
+that of course Tom had deserted long ago, and she wondered at seeing him
+place himself in her power again in this intrepid way. He said: "Mayn't
+I go and play now, aunt?"
+
+"What, a'ready? How much have you done?"
+
+"It's all done, aunt."
+
+"Tom, don't lie to me--I can't bear it."
+
+"I ain't, aunt; it IS all done."
+
+Aunt Polly placed small trust in such evidence. She went out to see
+for herself; and she would have been content to find twenty per cent.
+of Tom's statement true. When she found the entire fence whitewashed,
+and not only whitewashed but elaborately coated and recoated, and even
+a streak added to the ground, her astonishment was almost unspeakable.
+She said:
+
+"Well, I never! There's no getting round it, you can work when you're
+a mind to, Tom." And then she diluted the compliment by adding, "But
+it's powerful seldom you're a mind to, I'm bound to say. Well, go 'long
+and play; but mind you get back some time in a week, or I'll tan you."
+
+She was so overcome by the splendor of his achievement that she took
+him into the closet and selected a choice apple and delivered it to
+him, along with an improving lecture upon the added value and flavor a
+treat took to itself when it came without sin through virtuous effort.
+And while she closed with a happy Scriptural flourish, he "hooked" a
+doughnut.
+
+Then he skipped out, and saw Sid just starting up the outside stairway
+that led to the back rooms on the second floor. Clods were handy and
+the air was full of them in a twinkling. They raged around Sid like a
+hail-storm; and before Aunt Polly could collect her surprised faculties
+and sally to the rescue, six or seven clods had taken personal effect,
+and Tom was over the fence and gone. There was a gate, but as a general
+thing he was too crowded for time to make use of it. His soul was at
+peace, now that he had settled with Sid for calling attention to his
+black thread and getting him into trouble.
+
+Tom skirted the block, and came round into a muddy alley that led by
+the back of his aunt's cow-stable. He presently got safely beyond the
+reach of capture and punishment, and hastened toward the public square
+of the village, where two "military" companies of boys had met for
+conflict, according to previous appointment. Tom was General of one of
+these armies, Joe Harper (a bosom friend) General of the other. These
+two great commanders did not condescend to fight in person--that being
+better suited to the still smaller fry--but sat together on an eminence
+and conducted the field operations by orders delivered through
+aides-de-camp. Tom's army won a great victory, after a long and
+hard-fought battle. Then the dead were counted, prisoners exchanged,
+the terms of the next disagreement agreed upon, and the day for the
+necessary battle appointed; after which the armies fell into line and
+marched away, and Tom turned homeward alone.
+
+As he was passing by the house where Jeff Thatcher lived, he saw a new
+girl in the garden--a lovely little blue-eyed creature with yellow hair
+plaited into two long-tails, white summer frock and embroidered
+pantalettes. The fresh-crowned hero fell without firing a shot. A
+certain Amy Lawrence vanished out of his heart and left not even a
+memory of herself behind. He had thought he loved her to distraction;
+he had regarded his passion as adoration; and behold it was only a poor
+little evanescent partiality. He had been months winning her; she had
+confessed hardly a week ago; he had been the happiest and the proudest
+boy in the world only seven short days, and here in one instant of time
+she had gone out of his heart like a casual stranger whose visit is
+done.
+
+He worshipped this new angel with furtive eye, till he saw that she
+had discovered him; then he pretended he did not know she was present,
+and began to "show off" in all sorts of absurd boyish ways, in order to
+win her admiration. He kept up this grotesque foolishness for some
+time; but by-and-by, while he was in the midst of some dangerous
+gymnastic performances, he glanced aside and saw that the little girl
+was wending her way toward the house. Tom came up to the fence and
+leaned on it, grieving, and hoping she would tarry yet awhile longer.
+She halted a moment on the steps and then moved toward the door. Tom
+heaved a great sigh as she put her foot on the threshold. But his face
+lit up, right away, for she tossed a pansy over the fence a moment
+before she disappeared.
+
+The boy ran around and stopped within a foot or two of the flower, and
+then shaded his eyes with his hand and began to look down street as if
+he had discovered something of interest going on in that direction.
+Presently he picked up a straw and began trying to balance it on his
+nose, with his head tilted far back; and as he moved from side to side,
+in his efforts, he edged nearer and nearer toward the pansy; finally
+his bare foot rested upon it, his pliant toes closed upon it, and he
+hopped away with the treasure and disappeared round the corner. But
+only for a minute--only while he could button the flower inside his
+jacket, next his heart--or next his stomach, possibly, for he was not
+much posted in anatomy, and not hypercritical, anyway.
+
+He returned, now, and hung about the fence till nightfall, "showing
+off," as before; but the girl never exhibited herself again, though Tom
+comforted himself a little with the hope that she had been near some
+window, meantime, and been aware of his attentions. Finally he strode
+home reluctantly, with his poor head full of visions.
+
+All through supper his spirits were so high that his aunt wondered
+"what had got into the child." He took a good scolding about clodding
+Sid, and did not seem to mind it in the least. He tried to steal sugar
+under his aunt's very nose, and got his knuckles rapped for it. He said:
+
+"Aunt, you don't whack Sid when he takes it."
+
+"Well, Sid don't torment a body the way you do. You'd be always into
+that sugar if I warn't watching you."
+
+Presently she stepped into the kitchen, and Sid, happy in his
+immunity, reached for the sugar-bowl--a sort of glorying over Tom which
+was wellnigh unbearable. But Sid's fingers slipped and the bowl dropped
+and broke. Tom was in ecstasies. In such ecstasies that he even
+controlled his tongue and was silent. He said to himself that he would
+not speak a word, even when his aunt came in, but would sit perfectly
+still till she asked who did the mischief; and then he would tell, and
+there would be nothing so good in the world as to see that pet model
+"catch it." He was so brimful of exultation that he could hardly hold
+himself when the old lady came back and stood above the wreck
+discharging lightnings of wrath from over her spectacles. He said to
+himself, "Now it's coming!" And the next instant he was sprawling on
+the floor! The potent palm was uplifted to strike again when Tom cried
+out:
+
+"Hold on, now, what 'er you belting ME for?--Sid broke it!"
+
+Aunt Polly paused, perplexed, and Tom looked for healing pity. But
+when she got her tongue again, she only said:
+
+"Umf! Well, you didn't get a lick amiss, I reckon. You been into some
+other audacious mischief when I wasn't around, like enough."
+
+Then her conscience reproached her, and she yearned to say something
+kind and loving; but she judged that this would be construed into a
+confession that she had been in the wrong, and discipline forbade that.
+So she kept silence, and went about her affairs with a troubled heart.
+Tom sulked in a corner and exalted his woes. He knew that in her heart
+his aunt was on her knees to him, and he was morosely gratified by the
+consciousness of it. He would hang out no signals, he would take notice
+of none. He knew that a yearning glance fell upon him, now and then,
+through a film of tears, but he refused recognition of it. He pictured
+himself lying sick unto death and his aunt bending over him beseeching
+one little forgiving word, but he would turn his face to the wall, and
+die with that word unsaid. Ah, how would she feel then? And he pictured
+himself brought home from the river, dead, with his curls all wet, and
+his sore heart at rest. How she would throw herself upon him, and how
+her tears would fall like rain, and her lips pray God to give her back
+her boy and she would never, never abuse him any more! But he would lie
+there cold and white and make no sign--a poor little sufferer, whose
+griefs were at an end. He so worked upon his feelings with the pathos
+of these dreams, that he had to keep swallowing, he was so like to
+choke; and his eyes swam in a blur of water, which overflowed when he
+winked, and ran down and trickled from the end of his nose. And such a
+luxury to him was this petting of his sorrows, that he could not bear
+to have any worldly cheeriness or any grating delight intrude upon it;
+it was too sacred for such contact; and so, presently, when his cousin
+Mary danced in, all alive with the joy of seeing home again after an
+age-long visit of one week to the country, he got up and moved in
+clouds and darkness out at one door as she brought song and sunshine in
+at the other.
+
+He wandered far from the accustomed haunts of boys, and sought
+desolate places that were in harmony with his spirit. A log raft in the
+river invited him, and he seated himself on its outer edge and
+contemplated the dreary vastness of the stream, wishing, the while,
+that he could only be drowned, all at once and unconsciously, without
+undergoing the uncomfortable routine devised by nature. Then he thought
+of his flower. He got it out, rumpled and wilted, and it mightily
+increased his dismal felicity. He wondered if she would pity him if she
+knew? Would she cry, and wish that she had a right to put her arms
+around his neck and comfort him? Or would she turn coldly away like all
+the hollow world? This picture brought such an agony of pleasurable
+suffering that he worked it over and over again in his mind and set it
+up in new and varied lights, till he wore it threadbare. At last he
+rose up sighing and departed in the darkness.
+
+About half-past nine or ten o'clock he came along the deserted street
+to where the Adored Unknown lived; he paused a moment; no sound fell
+upon his listening ear; a candle was casting a dull glow upon the
+curtain of a second-story window. Was the sacred presence there? He
+climbed the fence, threaded his stealthy way through the plants, till
+he stood under that window; he looked up at it long, and with emotion;
+then he laid him down on the ground under it, disposing himself upon
+his back, with his hands clasped upon his breast and holding his poor
+wilted flower. And thus he would die--out in the cold world, with no
+shelter over his homeless head, no friendly hand to wipe the
+death-damps from his brow, no loving face to bend pityingly over him
+when the great agony came. And thus SHE would see him when she looked
+out upon the glad morning, and oh! would she drop one little tear upon
+his poor, lifeless form, would she heave one little sigh to see a bright
+young life so rudely blighted, so untimely cut down?
+
+The window went up, a maid-servant's discordant voice profaned the
+holy calm, and a deluge of water drenched the prone martyr's remains!
+
+The strangling hero sprang up with a relieving snort. There was a whiz
+as of a missile in the air, mingled with the murmur of a curse, a sound
+as of shivering glass followed, and a small, vague form went over the
+fence and shot away in the gloom.
+
+Not long after, as Tom, all undressed for bed, was surveying his
+drenched garments by the light of a tallow dip, Sid woke up; but if he
+had any dim idea of making any "references to allusions," he thought
+better of it and held his peace, for there was danger in Tom's eye.
+
+Tom turned in without the added vexation of prayers, and Sid made
+mental note of the omission.
+
+
+
+CHAPTER IV
+
+THE sun rose upon a tranquil world, and beamed down upon the peaceful
+village like a benediction. Breakfast over, Aunt Polly had family
+worship: it began with a prayer built from the ground up of solid
+courses of Scriptural quotations, welded together with a thin mortar of
+originality; and from the summit of this she delivered a grim chapter
+of the Mosaic Law, as from Sinai.
+
+Then Tom girded up his loins, so to speak, and went to work to "get
+his verses." Sid had learned his lesson days before. Tom bent all his
+energies to the memorizing of five verses, and he chose part of the
+Sermon on the Mount, because he could find no verses that were shorter.
+At the end of half an hour Tom had a vague general idea of his lesson,
+but no more, for his mind was traversing the whole field of human
+thought, and his hands were busy with distracting recreations. Mary
+took his book to hear him recite, and he tried to find his way through
+the fog:
+
+"Blessed are the--a--a--"
+
+"Poor"--
+
+"Yes--poor; blessed are the poor--a--a--"
+
+"In spirit--"
+
+"In spirit; blessed are the poor in spirit, for they--they--"
+
+"THEIRS--"
+
+"For THEIRS. Blessed are the poor in spirit, for theirs is the kingdom
+of heaven. Blessed are they that mourn, for they--they--"
+
+"Sh--"
+
+"For they--a--"
+
+"S, H, A--"
+
+"For they S, H--Oh, I don't know what it is!"
+
+"SHALL!"
+
+"Oh, SHALL! for they shall--for they shall--a--a--shall mourn--a--a--
+blessed are they that shall--they that--a--they that shall mourn, for
+they shall--a--shall WHAT? Why don't you tell me, Mary?--what do you
+want to be so mean for?"
+
+"Oh, Tom, you poor thick-headed thing, I'm not teasing you. I wouldn't
+do that. You must go and learn it again. Don't you be discouraged, Tom,
+you'll manage it--and if you do, I'll give you something ever so nice.
+There, now, that's a good boy."
+
+"All right! What is it, Mary, tell me what it is."
+
+"Never you mind, Tom. You know if I say it's nice, it is nice."
+
+"You bet you that's so, Mary. All right, I'll tackle it again."
+
+And he did "tackle it again"--and under the double pressure of
+curiosity and prospective gain he did it with such spirit that he
+accomplished a shining success. Mary gave him a brand-new "Barlow"
+knife worth twelve and a half cents; and the convulsion of delight that
+swept his system shook him to his foundations. True, the knife would
+not cut anything, but it was a "sure-enough" Barlow, and there was
+inconceivable grandeur in that--though where the Western boys ever got
+the idea that such a weapon could possibly be counterfeited to its
+injury is an imposing mystery and will always remain so, perhaps. Tom
+contrived to scarify the cupboard with it, and was arranging to begin
+on the bureau, when he was called off to dress for Sunday-school.
+
+Mary gave him a tin basin of water and a piece of soap, and he went
+outside the door and set the basin on a little bench there; then he
+dipped the soap in the water and laid it down; turned up his sleeves;
+poured out the water on the ground, gently, and then entered the
+kitchen and began to wipe his face diligently on the towel behind the
+door. But Mary removed the towel and said:
+
+"Now ain't you ashamed, Tom. You mustn't be so bad. Water won't hurt
+you."
+
+Tom was a trifle disconcerted. The basin was refilled, and this time
+he stood over it a little while, gathering resolution; took in a big
+breath and began. When he entered the kitchen presently, with both eyes
+shut and groping for the towel with his hands, an honorable testimony
+of suds and water was dripping from his face. But when he emerged from
+the towel, he was not yet satisfactory, for the clean territory stopped
+short at his chin and his jaws, like a mask; below and beyond this line
+there was a dark expanse of unirrigated soil that spread downward in
+front and backward around his neck. Mary took him in hand, and when she
+was done with him he was a man and a brother, without distinction of
+color, and his saturated hair was neatly brushed, and its short curls
+wrought into a dainty and symmetrical general effect. [He privately
+smoothed out the curls, with labor and difficulty, and plastered his
+hair close down to his head; for he held curls to be effeminate, and
+his own filled his life with bitterness.] Then Mary got out a suit of
+his clothing that had been used only on Sundays during two years--they
+were simply called his "other clothes"--and so by that we know the
+size of his wardrobe. The girl "put him to rights" after he had dressed
+himself; she buttoned his neat roundabout up to his chin, turned his
+vast shirt collar down over his shoulders, brushed him off and crowned
+him with his speckled straw hat. He now looked exceedingly improved and
+uncomfortable. He was fully as uncomfortable as he looked; for there
+was a restraint about whole clothes and cleanliness that galled him. He
+hoped that Mary would forget his shoes, but the hope was blighted; she
+coated them thoroughly with tallow, as was the custom, and brought them
+out. He lost his temper and said he was always being made to do
+everything he didn't want to do. But Mary said, persuasively:
+
+"Please, Tom--that's a good boy."
+
+So he got into the shoes snarling. Mary was soon ready, and the three
+children set out for Sunday-school--a place that Tom hated with his
+whole heart; but Sid and Mary were fond of it.
+
+Sabbath-school hours were from nine to half-past ten; and then church
+service. Two of the children always remained for the sermon
+voluntarily, and the other always remained too--for stronger reasons.
+The church's high-backed, uncushioned pews would seat about three
+hundred persons; the edifice was but a small, plain affair, with a sort
+of pine board tree-box on top of it for a steeple. At the door Tom
+dropped back a step and accosted a Sunday-dressed comrade:
+
+"Say, Billy, got a yaller ticket?"
+
+"Yes."
+
+"What'll you take for her?"
+
+"What'll you give?"
+
+"Piece of lickrish and a fish-hook."
+
+"Less see 'em."
+
+Tom exhibited. They were satisfactory, and the property changed hands.
+Then Tom traded a couple of white alleys for three red tickets, and
+some small trifle or other for a couple of blue ones. He waylaid other
+boys as they came, and went on buying tickets of various colors ten or
+fifteen minutes longer. He entered the church, now, with a swarm of
+clean and noisy boys and girls, proceeded to his seat and started a
+quarrel with the first boy that came handy. The teacher, a grave,
+elderly man, interfered; then turned his back a moment and Tom pulled a
+boy's hair in the next bench, and was absorbed in his book when the boy
+turned around; stuck a pin in another boy, presently, in order to hear
+him say "Ouch!" and got a new reprimand from his teacher. Tom's whole
+class were of a pattern--restless, noisy, and troublesome. When they
+came to recite their lessons, not one of them knew his verses
+perfectly, but had to be prompted all along. However, they worried
+through, and each got his reward--in small blue tickets, each with a
+passage of Scripture on it; each blue ticket was pay for two verses of
+the recitation. Ten blue tickets equalled a red one, and could be
+exchanged for it; ten red tickets equalled a yellow one; for ten yellow
+tickets the superintendent gave a very plainly bound Bible (worth forty
+cents in those easy times) to the pupil. How many of my readers would
+have the industry and application to memorize two thousand verses, even
+for a Dore Bible? And yet Mary had acquired two Bibles in this way--it
+was the patient work of two years--and a boy of German parentage had
+won four or five. He once recited three thousand verses without
+stopping; but the strain upon his mental faculties was too great, and
+he was little better than an idiot from that day forth--a grievous
+misfortune for the school, for on great occasions, before company, the
+superintendent (as Tom expressed it) had always made this boy come out
+and "spread himself." Only the older pupils managed to keep their
+tickets and stick to their tedious work long enough to get a Bible, and
+so the delivery of one of these prizes was a rare and noteworthy
+circumstance; the successful pupil was so great and conspicuous for
+that day that on the spot every scholar's heart was fired with a fresh
+ambition that often lasted a couple of weeks. It is possible that Tom's
+mental stomach had never really hungered for one of those prizes, but
+unquestionably his entire being had for many a day longed for the glory
+and the eclat that came with it.
+
+In due course the superintendent stood up in front of the pulpit, with
+a closed hymn-book in his hand and his forefinger inserted between its
+leaves, and commanded attention. When a Sunday-school superintendent
+makes his customary little speech, a hymn-book in the hand is as
+necessary as is the inevitable sheet of music in the hand of a singer
+who stands forward on the platform and sings a solo at a concert
+--though why, is a mystery: for neither the hymn-book nor the sheet of
+music is ever referred to by the sufferer. This superintendent was a
+slim creature of thirty-five, with a sandy goatee and short sandy hair;
+he wore a stiff standing-collar whose upper edge almost reached his
+ears and whose sharp points curved forward abreast the corners of his
+mouth--a fence that compelled a straight lookout ahead, and a turning
+of the whole body when a side view was required; his chin was propped
+on a spreading cravat which was as broad and as long as a bank-note,
+and had fringed ends; his boot toes were turned sharply up, in the
+fashion of the day, like sleigh-runners--an effect patiently and
+laboriously produced by the young men by sitting with their toes
+pressed against a wall for hours together. Mr. Walters was very earnest
+of mien, and very sincere and honest at heart; and he held sacred
+things and places in such reverence, and so separated them from worldly
+matters, that unconsciously to himself his Sunday-school voice had
+acquired a peculiar intonation which was wholly absent on week-days. He
+began after this fashion:
+
+"Now, children, I want you all to sit up just as straight and pretty
+as you can and give me all your attention for a minute or two. There
+--that is it. That is the way good little boys and girls should do. I see
+one little girl who is looking out of the window--I am afraid she
+thinks I am out there somewhere--perhaps up in one of the trees making
+a speech to the little birds. [Applausive titter.] I want to tell you
+how good it makes me feel to see so many bright, clean little faces
+assembled in a place like this, learning to do right and be good." And
+so forth and so on. It is not necessary to set down the rest of the
+oration. It was of a pattern which does not vary, and so it is familiar
+to us all.
+
+The latter third of the speech was marred by the resumption of fights
+and other recreations among certain of the bad boys, and by fidgetings
+and whisperings that extended far and wide, washing even to the bases
+of isolated and incorruptible rocks like Sid and Mary. But now every
+sound ceased suddenly, with the subsidence of Mr. Walters' voice, and
+the conclusion of the speech was received with a burst of silent
+gratitude.
+
+A good part of the whispering had been occasioned by an event which
+was more or less rare--the entrance of visitors: lawyer Thatcher,
+accompanied by a very feeble and aged man; a fine, portly, middle-aged
+gentleman with iron-gray hair; and a dignified lady who was doubtless
+the latter's wife. The lady was leading a child. Tom had been restless
+and full of chafings and repinings; conscience-smitten, too--he could
+not meet Amy Lawrence's eye, he could not brook her loving gaze. But
+when he saw this small new-comer his soul was all ablaze with bliss in
+a moment. The next moment he was "showing off" with all his might
+--cuffing boys, pulling hair, making faces--in a word, using every art
+that seemed likely to fascinate a girl and win her applause. His
+exaltation had but one alloy--the memory of his humiliation in this
+angel's garden--and that record in sand was fast washing out, under
+the waves of happiness that were sweeping over it now.
+
+The visitors were given the highest seat of honor, and as soon as Mr.
+Walters' speech was finished, he introduced them to the school. The
+middle-aged man turned out to be a prodigious personage--no less a one
+than the county judge--altogether the most august creation these
+children had ever looked upon--and they wondered what kind of material
+he was made of--and they half wanted to hear him roar, and were half
+afraid he might, too. He was from Constantinople, twelve miles away--so
+he had travelled, and seen the world--these very eyes had looked upon
+the county court-house--which was said to have a tin roof. The awe
+which these reflections inspired was attested by the impressive silence
+and the ranks of staring eyes. This was the great Judge Thatcher,
+brother of their own lawyer. Jeff Thatcher immediately went forward, to
+be familiar with the great man and be envied by the school. It would
+have been music to his soul to hear the whisperings:
+
+"Look at him, Jim! He's a going up there. Say--look! he's a going to
+shake hands with him--he IS shaking hands with him! By jings, don't you
+wish you was Jeff?"
+
+Mr. Walters fell to "showing off," with all sorts of official
+bustlings and activities, giving orders, delivering judgments,
+discharging directions here, there, everywhere that he could find a
+target. The librarian "showed off"--running hither and thither with his
+arms full of books and making a deal of the splutter and fuss that
+insect authority delights in. The young lady teachers "showed off"
+--bending sweetly over pupils that were lately being boxed, lifting
+pretty warning fingers at bad little boys and patting good ones
+lovingly. The young gentlemen teachers "showed off" with small
+scoldings and other little displays of authority and fine attention to
+discipline--and most of the teachers, of both sexes, found business up
+at the library, by the pulpit; and it was business that frequently had
+to be done over again two or three times (with much seeming vexation).
+The little girls "showed off" in various ways, and the little boys
+"showed off" with such diligence that the air was thick with paper wads
+and the murmur of scufflings. And above it all the great man sat and
+beamed a majestic judicial smile upon all the house, and warmed himself
+in the sun of his own grandeur--for he was "showing off," too.
+
+There was only one thing wanting to make Mr. Walters' ecstasy
+complete, and that was a chance to deliver a Bible-prize and exhibit a
+prodigy. Several pupils had a few yellow tickets, but none had enough
+--he had been around among the star pupils inquiring. He would have given
+worlds, now, to have that German lad back again with a sound mind.
+
+And now at this moment, when hope was dead, Tom Sawyer came forward
+with nine yellow tickets, nine red tickets, and ten blue ones, and
+demanded a Bible. This was a thunderbolt out of a clear sky. Walters
+was not expecting an application from this source for the next ten
+years. But there was no getting around it--here were the certified
+checks, and they were good for their face. Tom was therefore elevated
+to a place with the Judge and the other elect, and the great news was
+announced from headquarters. It was the most stunning surprise of the
+decade, and so profound was the sensation that it lifted the new hero
+up to the judicial one's altitude, and the school had two marvels to
+gaze upon in place of one. The boys were all eaten up with envy--but
+those that suffered the bitterest pangs were those who perceived too
+late that they themselves had contributed to this hated splendor by
+trading tickets to Tom for the wealth he had amassed in selling
+whitewashing privileges. These despised themselves, as being the dupes
+of a wily fraud, a guileful snake in the grass.
+
+The prize was delivered to Tom with as much effusion as the
+superintendent could pump up under the circumstances; but it lacked
+somewhat of the true gush, for the poor fellow's instinct taught him
+that there was a mystery here that could not well bear the light,
+perhaps; it was simply preposterous that this boy had warehoused two
+thousand sheaves of Scriptural wisdom on his premises--a dozen would
+strain his capacity, without a doubt.
+
+Amy Lawrence was proud and glad, and she tried to make Tom see it in
+her face--but he wouldn't look. She wondered; then she was just a grain
+troubled; next a dim suspicion came and went--came again; she watched;
+a furtive glance told her worlds--and then her heart broke, and she was
+jealous, and angry, and the tears came and she hated everybody. Tom
+most of all (she thought).
+
+Tom was introduced to the Judge; but his tongue was tied, his breath
+would hardly come, his heart quaked--partly because of the awful
+greatness of the man, but mainly because he was her parent. He would
+have liked to fall down and worship him, if it were in the dark. The
+Judge put his hand on Tom's head and called him a fine little man, and
+asked him what his name was. The boy stammered, gasped, and got it out:
+
+"Tom."
+
+"Oh, no, not Tom--it is--"
+
+"Thomas."
+
+"Ah, that's it. I thought there was more to it, maybe. That's very
+well. But you've another one I daresay, and you'll tell it to me, won't
+you?"
+
+"Tell the gentleman your other name, Thomas," said Walters, "and say
+sir. You mustn't forget your manners."
+
+"Thomas Sawyer--sir."
+
+"That's it! That's a good boy. Fine boy. Fine, manly little fellow.
+Two thousand verses is a great many--very, very great many. And you
+never can be sorry for the trouble you took to learn them; for
+knowledge is worth more than anything there is in the world; it's what
+makes great men and good men; you'll be a great man and a good man
+yourself, some day, Thomas, and then you'll look back and say, It's all
+owing to the precious Sunday-school privileges of my boyhood--it's all
+owing to my dear teachers that taught me to learn--it's all owing to
+the good superintendent, who encouraged me, and watched over me, and
+gave me a beautiful Bible--a splendid elegant Bible--to keep and have
+it all for my own, always--it's all owing to right bringing up! That is
+what you will say, Thomas--and you wouldn't take any money for those
+two thousand verses--no indeed you wouldn't. And now you wouldn't mind
+telling me and this lady some of the things you've learned--no, I know
+you wouldn't--for we are proud of little boys that learn. Now, no
+doubt you know the names of all the twelve disciples. Won't you tell us
+the names of the first two that were appointed?"
+
+Tom was tugging at a button-hole and looking sheepish. He blushed,
+now, and his eyes fell. Mr. Walters' heart sank within him. He said to
+himself, it is not possible that the boy can answer the simplest
+question--why DID the Judge ask him? Yet he felt obliged to speak up
+and say:
+
+"Answer the gentleman, Thomas--don't be afraid."
+
+Tom still hung fire.
+
+"Now I know you'll tell me," said the lady. "The names of the first
+two disciples were--"
+
+"DAVID AND GOLIAH!"
+
+Let us draw the curtain of charity over the rest of the scene.
+
+
+
+CHAPTER V
+
+ABOUT half-past ten the cracked bell of the small church began to
+ring, and presently the people began to gather for the morning sermon.
+The Sunday-school children distributed themselves about the house and
+occupied pews with their parents, so as to be under supervision. Aunt
+Polly came, and Tom and Sid and Mary sat with her--Tom being placed
+next the aisle, in order that he might be as far away from the open
+window and the seductive outside summer scenes as possible. The crowd
+filed up the aisles: the aged and needy postmaster, who had seen better
+days; the mayor and his wife--for they had a mayor there, among other
+unnecessaries; the justice of the peace; the widow Douglass, fair,
+smart, and forty, a generous, good-hearted soul and well-to-do, her
+hill mansion the only palace in the town, and the most hospitable and
+much the most lavish in the matter of festivities that St. Petersburg
+could boast; the bent and venerable Major and Mrs. Ward; lawyer
+Riverson, the new notable from a distance; next the belle of the
+village, followed by a troop of lawn-clad and ribbon-decked young
+heart-breakers; then all the young clerks in town in a body--for they
+had stood in the vestibule sucking their cane-heads, a circling wall of
+oiled and simpering admirers, till the last girl had run their gantlet;
+and last of all came the Model Boy, Willie Mufferson, taking as heedful
+care of his mother as if she were cut glass. He always brought his
+mother to church, and was the pride of all the matrons. The boys all
+hated him, he was so good. And besides, he had been "thrown up to them"
+so much. His white handkerchief was hanging out of his pocket behind, as
+usual on Sundays--accidentally. Tom had no handkerchief, and he looked
+upon boys who had as snobs.
+
+The congregation being fully assembled, now, the bell rang once more,
+to warn laggards and stragglers, and then a solemn hush fell upon the
+church which was only broken by the tittering and whispering of the
+choir in the gallery. The choir always tittered and whispered all
+through service. There was once a church choir that was not ill-bred,
+but I have forgotten where it was, now. It was a great many years ago,
+and I can scarcely remember anything about it, but I think it was in
+some foreign country.
+
+The minister gave out the hymn, and read it through with a relish, in
+a peculiar style which was much admired in that part of the country.
+His voice began on a medium key and climbed steadily up till it reached
+a certain point, where it bore with strong emphasis upon the topmost
+word and then plunged down as if from a spring-board:
+
+  Shall I be car-ri-ed toe the skies, on flow'ry BEDS of ease,
+
+  Whilst others fight to win the prize, and sail thro' BLOODY seas?
+
+He was regarded as a wonderful reader. At church "sociables" he was
+always called upon to read poetry; and when he was through, the ladies
+would lift up their hands and let them fall helplessly in their laps,
+and "wall" their eyes, and shake their heads, as much as to say, "Words
+cannot express it; it is too beautiful, TOO beautiful for this mortal
+earth."
+
+After the hymn had been sung, the Rev. Mr. Sprague turned himself into
+a bulletin-board, and read off "notices" of meetings and societies and
+things till it seemed that the list would stretch out to the crack of
+doom--a queer custom which is still kept up in America, even in cities,
+away here in this age of abundant newspapers. Often, the less there is
+to justify a traditional custom, the harder it is to get rid of it.
+
+And now the minister prayed. A good, generous prayer it was, and went
+into details: it pleaded for the church, and the little children of the
+church; for the other churches of the village; for the village itself;
+for the county; for the State; for the State officers; for the United
+States; for the churches of the United States; for Congress; for the
+President; for the officers of the Government; for poor sailors, tossed
+by stormy seas; for the oppressed millions groaning under the heel of
+European monarchies and Oriental despotisms; for such as have the light
+and the good tidings, and yet have not eyes to see nor ears to hear
+withal; for the heathen in the far islands of the sea; and closed with
+a supplication that the words he was about to speak might find grace
+and favor, and be as seed sown in fertile ground, yielding in time a
+grateful harvest of good. Amen.
+
+There was a rustling of dresses, and the standing congregation sat
+down. The boy whose history this book relates did not enjoy the prayer,
+he only endured it--if he even did that much. He was restive all
+through it; he kept tally of the details of the prayer, unconsciously
+--for he was not listening, but he knew the ground of old, and the
+clergyman's regular route over it--and when a little trifle of new
+matter was interlarded, his ear detected it and his whole nature
+resented it; he considered additions unfair, and scoundrelly. In the
+midst of the prayer a fly had lit on the back of the pew in front of
+him and tortured his spirit by calmly rubbing its hands together,
+embracing its head with its arms, and polishing it so vigorously that
+it seemed to almost part company with the body, and the slender thread
+of a neck was exposed to view; scraping its wings with its hind legs
+and smoothing them to its body as if they had been coat-tails; going
+through its whole toilet as tranquilly as if it knew it was perfectly
+safe. As indeed it was; for as sorely as Tom's hands itched to grab for
+it they did not dare--he believed his soul would be instantly destroyed
+if he did such a thing while the prayer was going on. But with the
+closing sentence his hand began to curve and steal forward; and the
+instant the "Amen" was out the fly was a prisoner of war. His aunt
+detected the act and made him let it go.
+
+The minister gave out his text and droned along monotonously through
+an argument that was so prosy that many a head by and by began to nod
+--and yet it was an argument that dealt in limitless fire and brimstone
+and thinned the predestined elect down to a company so small as to be
+hardly worth the saving. Tom counted the pages of the sermon; after
+church he always knew how many pages there had been, but he seldom knew
+anything else about the discourse. However, this time he was really
+interested for a little while. The minister made a grand and moving
+picture of the assembling together of the world's hosts at the
+millennium when the lion and the lamb should lie down together and a
+little child should lead them. But the pathos, the lesson, the moral of
+the great spectacle were lost upon the boy; he only thought of the
+conspicuousness of the principal character before the on-looking
+nations; his face lit with the thought, and he said to himself that he
+wished he could be that child, if it was a tame lion.
+
+Now he lapsed into suffering again, as the dry argument was resumed.
+Presently he bethought him of a treasure he had and got it out. It was
+a large black beetle with formidable jaws--a "pinchbug," he called it.
+It was in a percussion-cap box. The first thing the beetle did was to
+take him by the finger. A natural fillip followed, the beetle went
+floundering into the aisle and lit on its back, and the hurt finger
+went into the boy's mouth. The beetle lay there working its helpless
+legs, unable to turn over. Tom eyed it, and longed for it; but it was
+safe out of his reach. Other people uninterested in the sermon found
+relief in the beetle, and they eyed it too. Presently a vagrant poodle
+dog came idling along, sad at heart, lazy with the summer softness and
+the quiet, weary of captivity, sighing for change. He spied the beetle;
+the drooping tail lifted and wagged. He surveyed the prize; walked
+around it; smelt at it from a safe distance; walked around it again;
+grew bolder, and took a closer smell; then lifted his lip and made a
+gingerly snatch at it, just missing it; made another, and another;
+began to enjoy the diversion; subsided to his stomach with the beetle
+between his paws, and continued his experiments; grew weary at last,
+and then indifferent and absent-minded. His head nodded, and little by
+little his chin descended and touched the enemy, who seized it. There
+was a sharp yelp, a flirt of the poodle's head, and the beetle fell a
+couple of yards away, and lit on its back once more. The neighboring
+spectators shook with a gentle inward joy, several faces went behind
+fans and handkerchiefs, and Tom was entirely happy. The dog looked
+foolish, and probably felt so; but there was resentment in his heart,
+too, and a craving for revenge. So he went to the beetle and began a
+wary attack on it again; jumping at it from every point of a circle,
+lighting with his fore-paws within an inch of the creature, making even
+closer snatches at it with his teeth, and jerking his head till his
+ears flapped again. But he grew tired once more, after a while; tried
+to amuse himself with a fly but found no relief; followed an ant
+around, with his nose close to the floor, and quickly wearied of that;
+yawned, sighed, forgot the beetle entirely, and sat down on it. Then
+there was a wild yelp of agony and the poodle went sailing up the
+aisle; the yelps continued, and so did the dog; he crossed the house in
+front of the altar; he flew down the other aisle; he crossed before the
+doors; he clamored up the home-stretch; his anguish grew with his
+progress, till presently he was but a woolly comet moving in its orbit
+with the gleam and the speed of light. At last the frantic sufferer
+sheered from its course, and sprang into its master's lap; he flung it
+out of the window, and the voice of distress quickly thinned away and
+died in the distance.
+
+By this time the whole church was red-faced and suffocating with
+suppressed laughter, and the sermon had come to a dead standstill. The
+discourse was resumed presently, but it went lame and halting, all
+possibility of impressiveness being at an end; for even the gravest
+sentiments were constantly being received with a smothered burst of
+unholy mirth, under cover of some remote pew-back, as if the poor
+parson had said a rarely facetious thing. It was a genuine relief to
+the whole congregation when the ordeal was over and the benediction
+pronounced.
+
+Tom Sawyer went home quite cheerful, thinking to himself that there
+was some satisfaction about divine service when there was a bit of
+variety in it. He had but one marring thought; he was willing that the
+dog should play with his pinchbug, but he did not think it was upright
+in him to carry it off.
+
+
+
+CHAPTER VI
+
+MONDAY morning found Tom Sawyer miserable. Monday morning always found
+him so--because it began another week's slow suffering in school. He
+generally began that day with wishing he had had no intervening
+holiday, it made the going into captivity and fetters again so much
+more odious.
+
+Tom lay thinking. Presently it occurred to him that he wished he was
+sick; then he could stay home from school. Here was a vague
+possibility. He canvassed his system. No ailment was found, and he
+investigated again. This time he thought he could detect colicky
+symptoms, and he began to encourage them with considerable hope. But
+they soon grew feeble, and presently died wholly away. He reflected
+further. Suddenly he discovered something. One of his upper front teeth
+was loose. This was lucky; he was about to begin to groan, as a
+"starter," as he called it, when it occurred to him that if he came
+into court with that argument, his aunt would pull it out, and that
+would hurt. So he thought he would hold the tooth in reserve for the
+present, and seek further. Nothing offered for some little time, and
+then he remembered hearing the doctor tell about a certain thing that
+laid up a patient for two or three weeks and threatened to make him
+lose a finger. So the boy eagerly drew his sore toe from under the
+sheet and held it up for inspection. But now he did not know the
+necessary symptoms. However, it seemed well worth while to chance it,
+so he fell to groaning with considerable spirit.
+
+But Sid slept on unconscious.
+
+Tom groaned louder, and fancied that he began to feel pain in the toe.
+
+No result from Sid.
+
+Tom was panting with his exertions by this time. He took a rest and
+then swelled himself up and fetched a succession of admirable groans.
+
+Sid snored on.
+
+Tom was aggravated. He said, "Sid, Sid!" and shook him. This course
+worked well, and Tom began to groan again. Sid yawned, stretched, then
+brought himself up on his elbow with a snort, and began to stare at
+Tom. Tom went on groaning. Sid said:
+
+"Tom! Say, Tom!" [No response.] "Here, Tom! TOM! What is the matter,
+Tom?" And he shook him and looked in his face anxiously.
+
+Tom moaned out:
+
+"Oh, don't, Sid. Don't joggle me."
+
+"Why, what's the matter, Tom? I must call auntie."
+
+"No--never mind. It'll be over by and by, maybe. Don't call anybody."
+
+"But I must! DON'T groan so, Tom, it's awful. How long you been this
+way?"
+
+"Hours. Ouch! Oh, don't stir so, Sid, you'll kill me."
+
+"Tom, why didn't you wake me sooner? Oh, Tom, DON'T! It makes my
+flesh crawl to hear you. Tom, what is the matter?"
+
+"I forgive you everything, Sid. [Groan.] Everything you've ever done
+to me. When I'm gone--"
+
+"Oh, Tom, you ain't dying, are you? Don't, Tom--oh, don't. Maybe--"
+
+"I forgive everybody, Sid. [Groan.] Tell 'em so, Sid. And Sid, you
+give my window-sash and my cat with one eye to that new girl that's
+come to town, and tell her--"
+
+But Sid had snatched his clothes and gone. Tom was suffering in
+reality, now, so handsomely was his imagination working, and so his
+groans had gathered quite a genuine tone.
+
+Sid flew down-stairs and said:
+
+"Oh, Aunt Polly, come! Tom's dying!"
+
+"Dying!"
+
+"Yes'm. Don't wait--come quick!"
+
+"Rubbage! I don't believe it!"
+
+But she fled up-stairs, nevertheless, with Sid and Mary at her heels.
+And her face grew white, too, and her lip trembled. When she reached
+the bedside she gasped out:
+
+"You, Tom! Tom, what's the matter with you?"
+
+"Oh, auntie, I'm--"
+
+"What's the matter with you--what is the matter with you, child?"
+
+"Oh, auntie, my sore toe's mortified!"
+
+The old lady sank down into a chair and laughed a little, then cried a
+little, then did both together. This restored her and she said:
+
+"Tom, what a turn you did give me. Now you shut up that nonsense and
+climb out of this."
+
+The groans ceased and the pain vanished from the toe. The boy felt a
+little foolish, and he said:
+
+"Aunt Polly, it SEEMED mortified, and it hurt so I never minded my
+tooth at all."
+
+"Your tooth, indeed! What's the matter with your tooth?"
+
+"One of them's loose, and it aches perfectly awful."
+
+"There, there, now, don't begin that groaning again. Open your mouth.
+Well--your tooth IS loose, but you're not going to die about that.
+Mary, get me a silk thread, and a chunk of fire out of the kitchen."
+
+Tom said:
+
+"Oh, please, auntie, don't pull it out. It don't hurt any more. I wish
+I may never stir if it does. Please don't, auntie. I don't want to stay
+home from school."
+
+"Oh, you don't, don't you? So all this row was because you thought
+you'd get to stay home from school and go a-fishing? Tom, Tom, I love
+you so, and you seem to try every way you can to break my old heart
+with your outrageousness." By this time the dental instruments were
+ready. The old lady made one end of the silk thread fast to Tom's tooth
+with a loop and tied the other to the bedpost. Then she seized the
+chunk of fire and suddenly thrust it almost into the boy's face. The
+tooth hung dangling by the bedpost, now.
+
+But all trials bring their compensations. As Tom wended to school
+after breakfast, he was the envy of every boy he met because the gap in
+his upper row of teeth enabled him to expectorate in a new and
+admirable way. He gathered quite a following of lads interested in the
+exhibition; and one that had cut his finger and had been a centre of
+fascination and homage up to this time, now found himself suddenly
+without an adherent, and shorn of his glory. His heart was heavy, and
+he said with a disdain which he did not feel that it wasn't anything to
+spit like Tom Sawyer; but another boy said, "Sour grapes!" and he
+wandered away a dismantled hero.
+
+Shortly Tom came upon the juvenile pariah of the village, Huckleberry
+Finn, son of the town drunkard. Huckleberry was cordially hated and
+dreaded by all the mothers of the town, because he was idle and lawless
+and vulgar and bad--and because all their children admired him so, and
+delighted in his forbidden society, and wished they dared to be like
+him. Tom was like the rest of the respectable boys, in that he envied
+Huckleberry his gaudy outcast condition, and was under strict orders
+not to play with him. So he played with him every time he got a chance.
+Huckleberry was always dressed in the cast-off clothes of full-grown
+men, and they were in perennial bloom and fluttering with rags. His hat
+was a vast ruin with a wide crescent lopped out of its brim; his coat,
+when he wore one, hung nearly to his heels and had the rearward buttons
+far down the back; but one suspender supported his trousers; the seat
+of the trousers bagged low and contained nothing, the fringed legs
+dragged in the dirt when not rolled up.
+
+Huckleberry came and went, at his own free will. He slept on doorsteps
+in fine weather and in empty hogsheads in wet; he did not have to go to
+school or to church, or call any being master or obey anybody; he could
+go fishing or swimming when and where he chose, and stay as long as it
+suited him; nobody forbade him to fight; he could sit up as late as he
+pleased; he was always the first boy that went barefoot in the spring
+and the last to resume leather in the fall; he never had to wash, nor
+put on clean clothes; he could swear wonderfully. In a word, everything
+that goes to make life precious that boy had. So thought every
+harassed, hampered, respectable boy in St. Petersburg.
+
+Tom hailed the romantic outcast:
+
+"Hello, Huckleberry!"
+
+"Hello yourself, and see how you like it."
+
+"What's that you got?"
+
+"Dead cat."
+
+"Lemme see him, Huck. My, he's pretty stiff. Where'd you get him?"
+
+"Bought him off'n a boy."
+
+"What did you give?"
+
+"I give a blue ticket and a bladder that I got at the slaughter-house."
+
+"Where'd you get the blue ticket?"
+
+"Bought it off'n Ben Rogers two weeks ago for a hoop-stick."
+
+"Say--what is dead cats good for, Huck?"
+
+"Good for? Cure warts with."
+
+"No! Is that so? I know something that's better."
+
+"I bet you don't. What is it?"
+
+"Why, spunk-water."
+
+"Spunk-water! I wouldn't give a dern for spunk-water."
+
+"You wouldn't, wouldn't you? D'you ever try it?"
+
+"No, I hain't. But Bob Tanner did."
+
+"Who told you so!"
+
+"Why, he told Jeff Thatcher, and Jeff told Johnny Baker, and Johnny
+told Jim Hollis, and Jim told Ben Rogers, and Ben told a nigger, and
+the nigger told me. There now!"
+
+"Well, what of it? They'll all lie. Leastways all but the nigger. I
+don't know HIM. But I never see a nigger that WOULDN'T lie. Shucks! Now
+you tell me how Bob Tanner done it, Huck."
+
+"Why, he took and dipped his hand in a rotten stump where the
+rain-water was."
+
+"In the daytime?"
+
+"Certainly."
+
+"With his face to the stump?"
+
+"Yes. Least I reckon so."
+
+"Did he say anything?"
+
+"I don't reckon he did. I don't know."
+
+"Aha! Talk about trying to cure warts with spunk-water such a blame
+fool way as that! Why, that ain't a-going to do any good. You got to go
+all by yourself, to the middle of the woods, where you know there's a
+spunk-water stump, and just as it's midnight you back up against the
+stump and jam your hand in and say:
+
+  'Barley-corn, barley-corn, injun-meal shorts,
+   Spunk-water, spunk-water, swaller these warts,'
+
+and then walk away quick, eleven steps, with your eyes shut, and then
+turn around three times and walk home without speaking to anybody.
+Because if you speak the charm's busted."
+
+"Well, that sounds like a good way; but that ain't the way Bob Tanner
+done."
+
+"No, sir, you can bet he didn't, becuz he's the wartiest boy in this
+town; and he wouldn't have a wart on him if he'd knowed how to work
+spunk-water. I've took off thousands of warts off of my hands that way,
+Huck. I play with frogs so much that I've always got considerable many
+warts. Sometimes I take 'em off with a bean."
+
+"Yes, bean's good. I've done that."
+
+"Have you? What's your way?"
+
+"You take and split the bean, and cut the wart so as to get some
+blood, and then you put the blood on one piece of the bean and take and
+dig a hole and bury it 'bout midnight at the crossroads in the dark of
+the moon, and then you burn up the rest of the bean. You see that piece
+that's got the blood on it will keep drawing and drawing, trying to
+fetch the other piece to it, and so that helps the blood to draw the
+wart, and pretty soon off she comes."
+
+"Yes, that's it, Huck--that's it; though when you're burying it if you
+say 'Down bean; off wart; come no more to bother me!' it's better.
+That's the way Joe Harper does, and he's been nearly to Coonville and
+most everywheres. But say--how do you cure 'em with dead cats?"
+
+"Why, you take your cat and go and get in the graveyard 'long about
+midnight when somebody that was wicked has been buried; and when it's
+midnight a devil will come, or maybe two or three, but you can't see
+'em, you can only hear something like the wind, or maybe hear 'em talk;
+and when they're taking that feller away, you heave your cat after 'em
+and say, 'Devil follow corpse, cat follow devil, warts follow cat, I'm
+done with ye!' That'll fetch ANY wart."
+
+"Sounds right. D'you ever try it, Huck?"
+
+"No, but old Mother Hopkins told me."
+
+"Well, I reckon it's so, then. Becuz they say she's a witch."
+
+"Say! Why, Tom, I KNOW she is. She witched pap. Pap says so his own
+self. He come along one day, and he see she was a-witching him, so he
+took up a rock, and if she hadn't dodged, he'd a got her. Well, that
+very night he rolled off'n a shed wher' he was a layin drunk, and broke
+his arm."
+
+"Why, that's awful. How did he know she was a-witching him?"
+
+"Lord, pap can tell, easy. Pap says when they keep looking at you
+right stiddy, they're a-witching you. Specially if they mumble. Becuz
+when they mumble they're saying the Lord's Prayer backards."
+
+"Say, Hucky, when you going to try the cat?"
+
+"To-night. I reckon they'll come after old Hoss Williams to-night."
+
+"But they buried him Saturday. Didn't they get him Saturday night?"
+
+"Why, how you talk! How could their charms work till midnight?--and
+THEN it's Sunday. Devils don't slosh around much of a Sunday, I don't
+reckon."
+
+"I never thought of that. That's so. Lemme go with you?"
+
+"Of course--if you ain't afeard."
+
+"Afeard! 'Tain't likely. Will you meow?"
+
+"Yes--and you meow back, if you get a chance. Last time, you kep' me
+a-meowing around till old Hays went to throwing rocks at me and says
+'Dern that cat!' and so I hove a brick through his window--but don't
+you tell."
+
+"I won't. I couldn't meow that night, becuz auntie was watching me,
+but I'll meow this time. Say--what's that?"
+
+"Nothing but a tick."
+
+"Where'd you get him?"
+
+"Out in the woods."
+
+"What'll you take for him?"
+
+"I don't know. I don't want to sell him."
+
+"All right. It's a mighty small tick, anyway."
+
+"Oh, anybody can run a tick down that don't belong to them. I'm
+satisfied with it. It's a good enough tick for me."
+
+"Sho, there's ticks a plenty. I could have a thousand of 'em if I
+wanted to."
+
+"Well, why don't you? Becuz you know mighty well you can't. This is a
+pretty early tick, I reckon. It's the first one I've seen this year."
+
+"Say, Huck--I'll give you my tooth for him."
+
+"Less see it."
+
+Tom got out a bit of paper and carefully unrolled it. Huckleberry
+viewed it wistfully. The temptation was very strong. At last he said:
+
+"Is it genuwyne?"
+
+Tom lifted his lip and showed the vacancy.
+
+"Well, all right," said Huckleberry, "it's a trade."
+
+Tom enclosed the tick in the percussion-cap box that had lately been
+the pinchbug's prison, and the boys separated, each feeling wealthier
+than before.
+
+When Tom reached the little isolated frame schoolhouse, he strode in
+briskly, with the manner of one who had come with all honest speed.
+He hung his hat on a peg and flung himself into his seat with
+business-like alacrity. The master, throned on high in his great
+splint-bottom arm-chair, was dozing, lulled by the drowsy hum of study.
+The interruption roused him.
+
+"Thomas Sawyer!"
+
+Tom knew that when his name was pronounced in full, it meant trouble.
+
+"Sir!"
+
+"Come up here. Now, sir, why are you late again, as usual?"
+
+Tom was about to take refuge in a lie, when he saw two long tails of
+yellow hair hanging down a back that he recognized by the electric
+sympathy of love; and by that form was THE ONLY VACANT PLACE on the
+girls' side of the schoolhouse. He instantly said:
+
+"I STOPPED TO TALK WITH HUCKLEBERRY FINN!"
+
+The master's pulse stood still, and he stared helplessly. The buzz of
+study ceased. The pupils wondered if this foolhardy boy had lost his
+mind. The master said:
+
+"You--you did what?"
+
+"Stopped to talk with Huckleberry Finn."
+
+There was no mistaking the words.
+
+"Thomas Sawyer, this is the most astounding confession I have ever
+listened to. No mere ferule will answer for this offence. Take off your
+jacket."
+
+The master's arm performed until it was tired and the stock of
+switches notably diminished. Then the order followed:
+
+"Now, sir, go and sit with the girls! And let this be a warning to you."
+
+The titter that rippled around the room appeared to abash the boy, but
+in reality that result was caused rather more by his worshipful awe of
+his unknown idol and the dread pleasure that lay in his high good
+fortune. He sat down upon the end of the pine bench and the girl
+hitched herself away from him with a toss of her head. Nudges and winks
+and whispers traversed the room, but Tom sat still, with his arms upon
+the long, low desk before him, and seemed to study his book.
+
+By and by attention ceased from him, and the accustomed school murmur
+rose upon the dull air once more. Presently the boy began to steal
+furtive glances at the girl. She observed it, "made a mouth" at him and
+gave him the back of her head for the space of a minute. When she
+cautiously faced around again, a peach lay before her. She thrust it
+away. Tom gently put it back. She thrust it away again, but with less
+animosity. Tom patiently returned it to its place. Then she let it
+remain. Tom scrawled on his slate, "Please take it--I got more." The
+girl glanced at the words, but made no sign. Now the boy began to draw
+something on the slate, hiding his work with his left hand. For a time
+the girl refused to notice; but her human curiosity presently began to
+manifest itself by hardly perceptible signs. The boy worked on,
+apparently unconscious. The girl made a sort of noncommittal attempt to
+see, but the boy did not betray that he was aware of it. At last she
+gave in and hesitatingly whispered:
+
+"Let me see it."
+
+Tom partly uncovered a dismal caricature of a house with two gable
+ends to it and a corkscrew of smoke issuing from the chimney. Then the
+girl's interest began to fasten itself upon the work and she forgot
+everything else. When it was finished, she gazed a moment, then
+whispered:
+
+"It's nice--make a man."
+
+The artist erected a man in the front yard, that resembled a derrick.
+He could have stepped over the house; but the girl was not
+hypercritical; she was satisfied with the monster, and whispered:
+
+"It's a beautiful man--now make me coming along."
+
+Tom drew an hour-glass with a full moon and straw limbs to it and
+armed the spreading fingers with a portentous fan. The girl said:
+
+"It's ever so nice--I wish I could draw."
+
+"It's easy," whispered Tom, "I'll learn you."
+
+"Oh, will you? When?"
+
+"At noon. Do you go home to dinner?"
+
+"I'll stay if you will."
+
+"Good--that's a whack. What's your name?"
+
+"Becky Thatcher. What's yours? Oh, I know. It's Thomas Sawyer."
+
+"That's the name they lick me by. I'm Tom when I'm good. You call me
+Tom, will you?"
+
+"Yes."
+
+Now Tom began to scrawl something on the slate, hiding the words from
+the girl. But she was not backward this time. She begged to see. Tom
+said:
+
+"Oh, it ain't anything."
+
+"Yes it is."
+
+"No it ain't. You don't want to see."
+
+"Yes I do, indeed I do. Please let me."
+
+"You'll tell."
+
+"No I won't--deed and deed and double deed won't."
+
+"You won't tell anybody at all? Ever, as long as you live?"
+
+"No, I won't ever tell ANYbody. Now let me."
+
+"Oh, YOU don't want to see!"
+
+"Now that you treat me so, I WILL see." And she put her small hand
+upon his and a little scuffle ensued, Tom pretending to resist in
+earnest but letting his hand slip by degrees till these words were
+revealed: "I LOVE YOU."
+
+"Oh, you bad thing!" And she hit his hand a smart rap, but reddened
+and looked pleased, nevertheless.
+
+Just at this juncture the boy felt a slow, fateful grip closing on his
+ear, and a steady lifting impulse. In that wise he was borne across the
+house and deposited in his own seat, under a peppering fire of giggles
+from the whole school. Then the master stood over him during a few
+awful moments, and finally moved away to his throne without saying a
+word. But although Tom's ear tingled, his heart was jubilant.
+
+As the school quieted down Tom made an honest effort to study, but the
+turmoil within him was too great. In turn he took his place in the
+reading class and made a botch of it; then in the geography class and
+turned lakes into mountains, mountains into rivers, and rivers into
+continents, till chaos was come again; then in the spelling class, and
+got "turned down," by a succession of mere baby words, till he brought
+up at the foot and yielded up the pewter medal which he had worn with
+ostentation for months.
+
+
+
+CHAPTER VII
+
+THE harder Tom tried to fasten his mind on his book, the more his
+ideas wandered. So at last, with a sigh and a yawn, he gave it up. It
+seemed to him that the noon recess would never come. The air was
+utterly dead. There was not a breath stirring. It was the sleepiest of
+sleepy days. The drowsing murmur of the five and twenty studying
+scholars soothed the soul like the spell that is in the murmur of bees.
+Away off in the flaming sunshine, Cardiff Hill lifted its soft green
+sides through a shimmering veil of heat, tinted with the purple of
+distance; a few birds floated on lazy wing high in the air; no other
+living thing was visible but some cows, and they were asleep. Tom's
+heart ached to be free, or else to have something of interest to do to
+pass the dreary time. His hand wandered into his pocket and his face
+lit up with a glow of gratitude that was prayer, though he did not know
+it. Then furtively the percussion-cap box came out. He released the
+tick and put him on the long flat desk. The creature probably glowed
+with a gratitude that amounted to prayer, too, at this moment, but it
+was premature: for when he started thankfully to travel off, Tom turned
+him aside with a pin and made him take a new direction.
+
+Tom's bosom friend sat next him, suffering just as Tom had been, and
+now he was deeply and gratefully interested in this entertainment in an
+instant. This bosom friend was Joe Harper. The two boys were sworn
+friends all the week, and embattled enemies on Saturdays. Joe took a
+pin out of his lapel and began to assist in exercising the prisoner.
+The sport grew in interest momently. Soon Tom said that they were
+interfering with each other, and neither getting the fullest benefit of
+the tick. So he put Joe's slate on the desk and drew a line down the
+middle of it from top to bottom.
+
+"Now," said he, "as long as he is on your side you can stir him up and
+I'll let him alone; but if you let him get away and get on my side,
+you're to leave him alone as long as I can keep him from crossing over."
+
+"All right, go ahead; start him up."
+
+The tick escaped from Tom, presently, and crossed the equator. Joe
+harassed him awhile, and then he got away and crossed back again. This
+change of base occurred often. While one boy was worrying the tick with
+absorbing interest, the other would look on with interest as strong,
+the two heads bowed together over the slate, and the two souls dead to
+all things else. At last luck seemed to settle and abide with Joe. The
+tick tried this, that, and the other course, and got as excited and as
+anxious as the boys themselves, but time and again just as he would
+have victory in his very grasp, so to speak, and Tom's fingers would be
+twitching to begin, Joe's pin would deftly head him off, and keep
+possession. At last Tom could stand it no longer. The temptation was
+too strong. So he reached out and lent a hand with his pin. Joe was
+angry in a moment. Said he:
+
+"Tom, you let him alone."
+
+"I only just want to stir him up a little, Joe."
+
+"No, sir, it ain't fair; you just let him alone."
+
+"Blame it, I ain't going to stir him much."
+
+"Let him alone, I tell you."
+
+"I won't!"
+
+"You shall--he's on my side of the line."
+
+"Look here, Joe Harper, whose is that tick?"
+
+"I don't care whose tick he is--he's on my side of the line, and you
+sha'n't touch him."
+
+"Well, I'll just bet I will, though. He's my tick and I'll do what I
+blame please with him, or die!"
+
+A tremendous whack came down on Tom's shoulders, and its duplicate on
+Joe's; and for the space of two minutes the dust continued to fly from
+the two jackets and the whole school to enjoy it. The boys had been too
+absorbed to notice the hush that had stolen upon the school awhile
+before when the master came tiptoeing down the room and stood over
+them. He had contemplated a good part of the performance before he
+contributed his bit of variety to it.
+
+When school broke up at noon, Tom flew to Becky Thatcher, and
+whispered in her ear:
+
+"Put on your bonnet and let on you're going home; and when you get to
+the corner, give the rest of 'em the slip, and turn down through the
+lane and come back. I'll go the other way and come it over 'em the same
+way."
+
+So the one went off with one group of scholars, and the other with
+another. In a little while the two met at the bottom of the lane, and
+when they reached the school they had it all to themselves. Then they
+sat together, with a slate before them, and Tom gave Becky the pencil
+and held her hand in his, guiding it, and so created another surprising
+house. When the interest in art began to wane, the two fell to talking.
+Tom was swimming in bliss. He said:
+
+"Do you love rats?"
+
+"No! I hate them!"
+
+"Well, I do, too--LIVE ones. But I mean dead ones, to swing round your
+head with a string."
+
+"No, I don't care for rats much, anyway. What I like is chewing-gum."
+
+"Oh, I should say so! I wish I had some now."
+
+"Do you? I've got some. I'll let you chew it awhile, but you must give
+it back to me."
+
+That was agreeable, so they chewed it turn about, and dangled their
+legs against the bench in excess of contentment.
+
+"Was you ever at a circus?" said Tom.
+
+"Yes, and my pa's going to take me again some time, if I'm good."
+
+"I been to the circus three or four times--lots of times. Church ain't
+shucks to a circus. There's things going on at a circus all the time.
+I'm going to be a clown in a circus when I grow up."
+
+"Oh, are you! That will be nice. They're so lovely, all spotted up."
+
+"Yes, that's so. And they get slathers of money--most a dollar a day,
+Ben Rogers says. Say, Becky, was you ever engaged?"
+
+"What's that?"
+
+"Why, engaged to be married."
+
+"No."
+
+"Would you like to?"
+
+"I reckon so. I don't know. What is it like?"
+
+"Like? Why it ain't like anything. You only just tell a boy you won't
+ever have anybody but him, ever ever ever, and then you kiss and that's
+all. Anybody can do it."
+
+"Kiss? What do you kiss for?"
+
+"Why, that, you know, is to--well, they always do that."
+
+"Everybody?"
+
+"Why, yes, everybody that's in love with each other. Do you remember
+what I wrote on the slate?"
+
+"Ye--yes."
+
+"What was it?"
+
+"I sha'n't tell you."
+
+"Shall I tell YOU?"
+
+"Ye--yes--but some other time."
+
+"No, now."
+
+"No, not now--to-morrow."
+
+"Oh, no, NOW. Please, Becky--I'll whisper it, I'll whisper it ever so
+easy."
+
+Becky hesitating, Tom took silence for consent, and passed his arm
+about her waist and whispered the tale ever so softly, with his mouth
+close to her ear. And then he added:
+
+"Now you whisper it to me--just the same."
+
+She resisted, for a while, and then said:
+
+"You turn your face away so you can't see, and then I will. But you
+mustn't ever tell anybody--WILL you, Tom? Now you won't, WILL you?"
+
+"No, indeed, indeed I won't. Now, Becky."
+
+He turned his face away. She bent timidly around till her breath
+stirred his curls and whispered, "I--love--you!"
+
+Then she sprang away and ran around and around the desks and benches,
+with Tom after her, and took refuge in a corner at last, with her
+little white apron to her face. Tom clasped her about her neck and
+pleaded:
+
+"Now, Becky, it's all done--all over but the kiss. Don't you be afraid
+of that--it ain't anything at all. Please, Becky." And he tugged at her
+apron and the hands.
+
+By and by she gave up, and let her hands drop; her face, all glowing
+with the struggle, came up and submitted. Tom kissed the red lips and
+said:
+
+"Now it's all done, Becky. And always after this, you know, you ain't
+ever to love anybody but me, and you ain't ever to marry anybody but
+me, ever never and forever. Will you?"
+
+"No, I'll never love anybody but you, Tom, and I'll never marry
+anybody but you--and you ain't to ever marry anybody but me, either."
+
+"Certainly. Of course. That's PART of it. And always coming to school
+or when we're going home, you're to walk with me, when there ain't
+anybody looking--and you choose me and I choose you at parties, because
+that's the way you do when you're engaged."
+
+"It's so nice. I never heard of it before."
+
+"Oh, it's ever so gay! Why, me and Amy Lawrence--"
+
+The big eyes told Tom his blunder and he stopped, confused.
+
+"Oh, Tom! Then I ain't the first you've ever been engaged to!"
+
+The child began to cry. Tom said:
+
+"Oh, don't cry, Becky, I don't care for her any more."
+
+"Yes, you do, Tom--you know you do."
+
+Tom tried to put his arm about her neck, but she pushed him away and
+turned her face to the wall, and went on crying. Tom tried again, with
+soothing words in his mouth, and was repulsed again. Then his pride was
+up, and he strode away and went outside. He stood about, restless and
+uneasy, for a while, glancing at the door, every now and then, hoping
+she would repent and come to find him. But she did not. Then he began
+to feel badly and fear that he was in the wrong. It was a hard struggle
+with him to make new advances, now, but he nerved himself to it and
+entered. She was still standing back there in the corner, sobbing, with
+her face to the wall. Tom's heart smote him. He went to her and stood a
+moment, not knowing exactly how to proceed. Then he said hesitatingly:
+
+"Becky, I--I don't care for anybody but you."
+
+No reply--but sobs.
+
+"Becky"--pleadingly. "Becky, won't you say something?"
+
+More sobs.
+
+Tom got out his chiefest jewel, a brass knob from the top of an
+andiron, and passed it around her so that she could see it, and said:
+
+"Please, Becky, won't you take it?"
+
+She struck it to the floor. Then Tom marched out of the house and over
+the hills and far away, to return to school no more that day. Presently
+Becky began to suspect. She ran to the door; he was not in sight; she
+flew around to the play-yard; he was not there. Then she called:
+
+"Tom! Come back, Tom!"
+
+She listened intently, but there was no answer. She had no companions
+but silence and loneliness. So she sat down to cry again and upbraid
+herself; and by this time the scholars began to gather again, and she
+had to hide her griefs and still her broken heart and take up the cross
+of a long, dreary, aching afternoon, with none among the strangers
+about her to exchange sorrows with.
+
+
+
+CHAPTER VIII
+
+TOM dodged hither and thither through lanes until he was well out of
+the track of returning scholars, and then fell into a moody jog. He
+crossed a small "branch" two or three times, because of a prevailing
+juvenile superstition that to cross water baffled pursuit. Half an hour
+later he was disappearing behind the Douglas mansion on the summit of
+Cardiff Hill, and the schoolhouse was hardly distinguishable away off
+in the valley behind him. He entered a dense wood, picked his pathless
+way to the centre of it, and sat down on a mossy spot under a spreading
+oak. There was not even a zephyr stirring; the dead noonday heat had
+even stilled the songs of the birds; nature lay in a trance that was
+broken by no sound but the occasional far-off hammering of a
+woodpecker, and this seemed to render the pervading silence and sense
+of loneliness the more profound. The boy's soul was steeped in
+melancholy; his feelings were in happy accord with his surroundings. He
+sat long with his elbows on his knees and his chin in his hands,
+meditating. It seemed to him that life was but a trouble, at best, and
+he more than half envied Jimmy Hodges, so lately released; it must be
+very peaceful, he thought, to lie and slumber and dream forever and
+ever, with the wind whispering through the trees and caressing the
+grass and the flowers over the grave, and nothing to bother and grieve
+about, ever any more. If he only had a clean Sunday-school record he
+could be willing to go, and be done with it all. Now as to this girl.
+What had he done? Nothing. He had meant the best in the world, and been
+treated like a dog--like a very dog. She would be sorry some day--maybe
+when it was too late. Ah, if he could only die TEMPORARILY!
+
+But the elastic heart of youth cannot be compressed into one
+constrained shape long at a time. Tom presently began to drift
+insensibly back into the concerns of this life again. What if he turned
+his back, now, and disappeared mysteriously? What if he went away--ever
+so far away, into unknown countries beyond the seas--and never came
+back any more! How would she feel then! The idea of being a clown
+recurred to him now, only to fill him with disgust. For frivolity and
+jokes and spotted tights were an offense, when they intruded themselves
+upon a spirit that was exalted into the vague august realm of the
+romantic. No, he would be a soldier, and return after long years, all
+war-worn and illustrious. No--better still, he would join the Indians,
+and hunt buffaloes and go on the warpath in the mountain ranges and the
+trackless great plains of the Far West, and away in the future come
+back a great chief, bristling with feathers, hideous with paint, and
+prance into Sunday-school, some drowsy summer morning, with a
+bloodcurdling war-whoop, and sear the eyeballs of all his companions
+with unappeasable envy. But no, there was something gaudier even than
+this. He would be a pirate! That was it! NOW his future lay plain
+before him, and glowing with unimaginable splendor. How his name would
+fill the world, and make people shudder! How gloriously he would go
+plowing the dancing seas, in his long, low, black-hulled racer, the
+Spirit of the Storm, with his grisly flag flying at the fore! And at
+the zenith of his fame, how he would suddenly appear at the old village
+and stalk into church, brown and weather-beaten, in his black velvet
+doublet and trunks, his great jack-boots, his crimson sash, his belt
+bristling with horse-pistols, his crime-rusted cutlass at his side, his
+slouch hat with waving plumes, his black flag unfurled, with the skull
+and crossbones on it, and hear with swelling ecstasy the whisperings,
+"It's Tom Sawyer the Pirate!--the Black Avenger of the Spanish Main!"
+
+Yes, it was settled; his career was determined. He would run away from
+home and enter upon it. He would start the very next morning. Therefore
+he must now begin to get ready. He would collect his resources
+together. He went to a rotten log near at hand and began to dig under
+one end of it with his Barlow knife. He soon struck wood that sounded
+hollow. He put his hand there and uttered this incantation impressively:
+
+"What hasn't come here, come! What's here, stay here!"
+
+Then he scraped away the dirt, and exposed a pine shingle. He took it
+up and disclosed a shapely little treasure-house whose bottom and sides
+were of shingles. In it lay a marble. Tom's astonishment was boundless!
+He scratched his head with a perplexed air, and said:
+
+"Well, that beats anything!"
+
+Then he tossed the marble away pettishly, and stood cogitating. The
+truth was, that a superstition of his had failed, here, which he and
+all his comrades had always looked upon as infallible. If you buried a
+marble with certain necessary incantations, and left it alone a
+fortnight, and then opened the place with the incantation he had just
+used, you would find that all the marbles you had ever lost had
+gathered themselves together there, meantime, no matter how widely they
+had been separated. But now, this thing had actually and unquestionably
+failed. Tom's whole structure of faith was shaken to its foundations.
+He had many a time heard of this thing succeeding but never of its
+failing before. It did not occur to him that he had tried it several
+times before, himself, but could never find the hiding-places
+afterward. He puzzled over the matter some time, and finally decided
+that some witch had interfered and broken the charm. He thought he
+would satisfy himself on that point; so he searched around till he
+found a small sandy spot with a little funnel-shaped depression in it.
+He laid himself down and put his mouth close to this depression and
+called--
+
+"Doodle-bug, doodle-bug, tell me what I want to know! Doodle-bug,
+doodle-bug, tell me what I want to know!"
+
+The sand began to work, and presently a small black bug appeared for a
+second and then darted under again in a fright.
+
+"He dasn't tell! So it WAS a witch that done it. I just knowed it."
+
+He well knew the futility of trying to contend against witches, so he
+gave up discouraged. But it occurred to him that he might as well have
+the marble he had just thrown away, and therefore he went and made a
+patient search for it. But he could not find it. Now he went back to
+his treasure-house and carefully placed himself just as he had been
+standing when he tossed the marble away; then he took another marble
+from his pocket and tossed it in the same way, saying:
+
+"Brother, go find your brother!"
+
+He watched where it stopped, and went there and looked. But it must
+have fallen short or gone too far; so he tried twice more. The last
+repetition was successful. The two marbles lay within a foot of each
+other.
+
+Just here the blast of a toy tin trumpet came faintly down the green
+aisles of the forest. Tom flung off his jacket and trousers, turned a
+suspender into a belt, raked away some brush behind the rotten log,
+disclosing a rude bow and arrow, a lath sword and a tin trumpet, and in
+a moment had seized these things and bounded away, barelegged, with
+fluttering shirt. He presently halted under a great elm, blew an
+answering blast, and then began to tiptoe and look warily out, this way
+and that. He said cautiously--to an imaginary company:
+
+"Hold, my merry men! Keep hid till I blow."
+
+Now appeared Joe Harper, as airily clad and elaborately armed as Tom.
+Tom called:
+
+"Hold! Who comes here into Sherwood Forest without my pass?"
+
+"Guy of Guisborne wants no man's pass. Who art thou that--that--"
+
+"Dares to hold such language," said Tom, prompting--for they talked
+"by the book," from memory.
+
+"Who art thou that dares to hold such language?"
+
+"I, indeed! I am Robin Hood, as thy caitiff carcase soon shall know."
+
+"Then art thou indeed that famous outlaw? Right gladly will I dispute
+with thee the passes of the merry wood. Have at thee!"
+
+They took their lath swords, dumped their other traps on the ground,
+struck a fencing attitude, foot to foot, and began a grave, careful
+combat, "two up and two down." Presently Tom said:
+
+"Now, if you've got the hang, go it lively!"
+
+So they "went it lively," panting and perspiring with the work. By and
+by Tom shouted:
+
+"Fall! fall! Why don't you fall?"
+
+"I sha'n't! Why don't you fall yourself? You're getting the worst of
+it."
+
+"Why, that ain't anything. I can't fall; that ain't the way it is in
+the book. The book says, 'Then with one back-handed stroke he slew poor
+Guy of Guisborne.' You're to turn around and let me hit you in the
+back."
+
+There was no getting around the authorities, so Joe turned, received
+the whack and fell.
+
+"Now," said Joe, getting up, "you got to let me kill YOU. That's fair."
+
+"Why, I can't do that, it ain't in the book."
+
+"Well, it's blamed mean--that's all."
+
+"Well, say, Joe, you can be Friar Tuck or Much the miller's son, and
+lam me with a quarter-staff; or I'll be the Sheriff of Nottingham and
+you be Robin Hood a little while and kill me."
+
+This was satisfactory, and so these adventures were carried out. Then
+Tom became Robin Hood again, and was allowed by the treacherous nun to
+bleed his strength away through his neglected wound. And at last Joe,
+representing a whole tribe of weeping outlaws, dragged him sadly forth,
+gave his bow into his feeble hands, and Tom said, "Where this arrow
+falls, there bury poor Robin Hood under the greenwood tree." Then he
+shot the arrow and fell back and would have died, but he lit on a
+nettle and sprang up too gaily for a corpse.
+
+The boys dressed themselves, hid their accoutrements, and went off
+grieving that there were no outlaws any more, and wondering what modern
+civilization could claim to have done to compensate for their loss.
+They said they would rather be outlaws a year in Sherwood Forest than
+President of the United States forever.
+
+
+
+CHAPTER IX
+
+AT half-past nine, that night, Tom and Sid were sent to bed, as usual.
+They said their prayers, and Sid was soon asleep. Tom lay awake and
+waited, in restless impatience. When it seemed to him that it must be
+nearly daylight, he heard the clock strike ten! This was despair. He
+would have tossed and fidgeted, as his nerves demanded, but he was
+afraid he might wake Sid. So he lay still, and stared up into the dark.
+Everything was dismally still. By and by, out of the stillness, little,
+scarcely perceptible noises began to emphasize themselves. The ticking
+of the clock began to bring itself into notice. Old beams began to
+crack mysteriously. The stairs creaked faintly. Evidently spirits were
+abroad. A measured, muffled snore issued from Aunt Polly's chamber. And
+now the tiresome chirping of a cricket that no human ingenuity could
+locate, began. Next the ghastly ticking of a deathwatch in the wall at
+the bed's head made Tom shudder--it meant that somebody's days were
+numbered. Then the howl of a far-off dog rose on the night air, and was
+answered by a fainter howl from a remoter distance. Tom was in an
+agony. At last he was satisfied that time had ceased and eternity
+begun; he began to doze, in spite of himself; the clock chimed eleven,
+but he did not hear it. And then there came, mingling with his
+half-formed dreams, a most melancholy caterwauling. The raising of a
+neighboring window disturbed him. A cry of "Scat! you devil!" and the
+crash of an empty bottle against the back of his aunt's woodshed
+brought him wide awake, and a single minute later he was dressed and
+out of the window and creeping along the roof of the "ell" on all
+fours. He "meow'd" with caution once or twice, as he went; then jumped
+to the roof of the woodshed and thence to the ground. Huckleberry Finn
+was there, with his dead cat. The boys moved off and disappeared in the
+gloom. At the end of half an hour they were wading through the tall
+grass of the graveyard.
+
+It was a graveyard of the old-fashioned Western kind. It was on a
+hill, about a mile and a half from the village. It had a crazy board
+fence around it, which leaned inward in places, and outward the rest of
+the time, but stood upright nowhere. Grass and weeds grew rank over the
+whole cemetery. All the old graves were sunken in, there was not a
+tombstone on the place; round-topped, worm-eaten boards staggered over
+the graves, leaning for support and finding none. "Sacred to the memory
+of" So-and-So had been painted on them once, but it could no longer
+have been read, on the most of them, now, even if there had been light.
+
+A faint wind moaned through the trees, and Tom feared it might be the
+spirits of the dead, complaining at being disturbed. The boys talked
+little, and only under their breath, for the time and the place and the
+pervading solemnity and silence oppressed their spirits. They found the
+sharp new heap they were seeking, and ensconced themselves within the
+protection of three great elms that grew in a bunch within a few feet
+of the grave.
+
+Then they waited in silence for what seemed a long time. The hooting
+of a distant owl was all the sound that troubled the dead stillness.
+Tom's reflections grew oppressive. He must force some talk. So he said
+in a whisper:
+
+"Hucky, do you believe the dead people like it for us to be here?"
+
+Huckleberry whispered:
+
+"I wisht I knowed. It's awful solemn like, AIN'T it?"
+
+"I bet it is."
+
+There was a considerable pause, while the boys canvassed this matter
+inwardly. Then Tom whispered:
+
+"Say, Hucky--do you reckon Hoss Williams hears us talking?"
+
+"O' course he does. Least his sperrit does."
+
+Tom, after a pause:
+
+"I wish I'd said Mister Williams. But I never meant any harm.
+Everybody calls him Hoss."
+
+"A body can't be too partic'lar how they talk 'bout these-yer dead
+people, Tom."
+
+This was a damper, and conversation died again.
+
+Presently Tom seized his comrade's arm and said:
+
+"Sh!"
+
+"What is it, Tom?" And the two clung together with beating hearts.
+
+"Sh! There 'tis again! Didn't you hear it?"
+
+"I--"
+
+"There! Now you hear it."
+
+"Lord, Tom, they're coming! They're coming, sure. What'll we do?"
+
+"I dono. Think they'll see us?"
+
+"Oh, Tom, they can see in the dark, same as cats. I wisht I hadn't
+come."
+
+"Oh, don't be afeard. I don't believe they'll bother us. We ain't
+doing any harm. If we keep perfectly still, maybe they won't notice us
+at all."
+
+"I'll try to, Tom, but, Lord, I'm all of a shiver."
+
+"Listen!"
+
+The boys bent their heads together and scarcely breathed. A muffled
+sound of voices floated up from the far end of the graveyard.
+
+"Look! See there!" whispered Tom. "What is it?"
+
+"It's devil-fire. Oh, Tom, this is awful."
+
+Some vague figures approached through the gloom, swinging an
+old-fashioned tin lantern that freckled the ground with innumerable
+little spangles of light. Presently Huckleberry whispered with a
+shudder:
+
+"It's the devils sure enough. Three of 'em! Lordy, Tom, we're goners!
+Can you pray?"
+
+"I'll try, but don't you be afeard. They ain't going to hurt us. 'Now
+I lay me down to sleep, I--'"
+
+"Sh!"
+
+"What is it, Huck?"
+
+"They're HUMANS! One of 'em is, anyway. One of 'em's old Muff Potter's
+voice."
+
+"No--'tain't so, is it?"
+
+"I bet I know it. Don't you stir nor budge. He ain't sharp enough to
+notice us. Drunk, the same as usual, likely--blamed old rip!"
+
+"All right, I'll keep still. Now they're stuck. Can't find it. Here
+they come again. Now they're hot. Cold again. Hot again. Red hot!
+They're p'inted right, this time. Say, Huck, I know another o' them
+voices; it's Injun Joe."
+
+"That's so--that murderin' half-breed! I'd druther they was devils a
+dern sight. What kin they be up to?"
+
+The whisper died wholly out, now, for the three men had reached the
+grave and stood within a few feet of the boys' hiding-place.
+
+"Here it is," said the third voice; and the owner of it held the
+lantern up and revealed the face of young Doctor Robinson.
+
+Potter and Injun Joe were carrying a handbarrow with a rope and a
+couple of shovels on it. They cast down their load and began to open
+the grave. The doctor put the lantern at the head of the grave and came
+and sat down with his back against one of the elm trees. He was so
+close the boys could have touched him.
+
+"Hurry, men!" he said, in a low voice; "the moon might come out at any
+moment."
+
+They growled a response and went on digging. For some time there was
+no noise but the grating sound of the spades discharging their freight
+of mould and gravel. It was very monotonous. Finally a spade struck
+upon the coffin with a dull woody accent, and within another minute or
+two the men had hoisted it out on the ground. They pried off the lid
+with their shovels, got out the body and dumped it rudely on the
+ground. The moon drifted from behind the clouds and exposed the pallid
+face. The barrow was got ready and the corpse placed on it, covered
+with a blanket, and bound to its place with the rope. Potter took out a
+large spring-knife and cut off the dangling end of the rope and then
+said:
+
+"Now the cussed thing's ready, Sawbones, and you'll just out with
+another five, or here she stays."
+
+"That's the talk!" said Injun Joe.
+
+"Look here, what does this mean?" said the doctor. "You required your
+pay in advance, and I've paid you."
+
+"Yes, and you done more than that," said Injun Joe, approaching the
+doctor, who was now standing. "Five years ago you drove me away from
+your father's kitchen one night, when I come to ask for something to
+eat, and you said I warn't there for any good; and when I swore I'd get
+even with you if it took a hundred years, your father had me jailed for
+a vagrant. Did you think I'd forget? The Injun blood ain't in me for
+nothing. And now I've GOT you, and you got to SETTLE, you know!"
+
+He was threatening the doctor, with his fist in his face, by this
+time. The doctor struck out suddenly and stretched the ruffian on the
+ground. Potter dropped his knife, and exclaimed:
+
+"Here, now, don't you hit my pard!" and the next moment he had
+grappled with the doctor and the two were struggling with might and
+main, trampling the grass and tearing the ground with their heels.
+Injun Joe sprang to his feet, his eyes flaming with passion, snatched
+up Potter's knife, and went creeping, catlike and stooping, round and
+round about the combatants, seeking an opportunity. All at once the
+doctor flung himself free, seized the heavy headboard of Williams'
+grave and felled Potter to the earth with it--and in the same instant
+the half-breed saw his chance and drove the knife to the hilt in the
+young man's breast. He reeled and fell partly upon Potter, flooding him
+with his blood, and in the same moment the clouds blotted out the
+dreadful spectacle and the two frightened boys went speeding away in
+the dark.
+
+Presently, when the moon emerged again, Injun Joe was standing over
+the two forms, contemplating them. The doctor murmured inarticulately,
+gave a long gasp or two and was still. The half-breed muttered:
+
+"THAT score is settled--damn you."
+
+Then he robbed the body. After which he put the fatal knife in
+Potter's open right hand, and sat down on the dismantled coffin. Three
+--four--five minutes passed, and then Potter began to stir and moan. His
+hand closed upon the knife; he raised it, glanced at it, and let it
+fall, with a shudder. Then he sat up, pushing the body from him, and
+gazed at it, and then around him, confusedly. His eyes met Joe's.
+
+"Lord, how is this, Joe?" he said.
+
+"It's a dirty business," said Joe, without moving.
+
+"What did you do it for?"
+
+"I! I never done it!"
+
+"Look here! That kind of talk won't wash."
+
+Potter trembled and grew white.
+
+"I thought I'd got sober. I'd no business to drink to-night. But it's
+in my head yet--worse'n when we started here. I'm all in a muddle;
+can't recollect anything of it, hardly. Tell me, Joe--HONEST, now, old
+feller--did I do it? Joe, I never meant to--'pon my soul and honor, I
+never meant to, Joe. Tell me how it was, Joe. Oh, it's awful--and him
+so young and promising."
+
+"Why, you two was scuffling, and he fetched you one with the headboard
+and you fell flat; and then up you come, all reeling and staggering
+like, and snatched the knife and jammed it into him, just as he fetched
+you another awful clip--and here you've laid, as dead as a wedge til
+now."
+
+"Oh, I didn't know what I was a-doing. I wish I may die this minute if
+I did. It was all on account of the whiskey and the excitement, I
+reckon. I never used a weepon in my life before, Joe. I've fought, but
+never with weepons. They'll all say that. Joe, don't tell! Say you
+won't tell, Joe--that's a good feller. I always liked you, Joe, and
+stood up for you, too. Don't you remember? You WON'T tell, WILL you,
+Joe?" And the poor creature dropped on his knees before the stolid
+murderer, and clasped his appealing hands.
+
+"No, you've always been fair and square with me, Muff Potter, and I
+won't go back on you. There, now, that's as fair as a man can say."
+
+"Oh, Joe, you're an angel. I'll bless you for this the longest day I
+live." And Potter began to cry.
+
+"Come, now, that's enough of that. This ain't any time for blubbering.
+You be off yonder way and I'll go this. Move, now, and don't leave any
+tracks behind you."
+
+Potter started on a trot that quickly increased to a run. The
+half-breed stood looking after him. He muttered:
+
+"If he's as much stunned with the lick and fuddled with the rum as he
+had the look of being, he won't think of the knife till he's gone so
+far he'll be afraid to come back after it to such a place by himself
+--chicken-heart!"
+
+Two or three minutes later the murdered man, the blanketed corpse, the
+lidless coffin, and the open grave were under no inspection but the
+moon's. The stillness was complete again, too.
+
+
+
+CHAPTER X
+
+THE two boys flew on and on, toward the village, speechless with
+horror. They glanced backward over their shoulders from time to time,
+apprehensively, as if they feared they might be followed. Every stump
+that started up in their path seemed a man and an enemy, and made them
+catch their breath; and as they sped by some outlying cottages that lay
+near the village, the barking of the aroused watch-dogs seemed to give
+wings to their feet.
+
+"If we can only get to the old tannery before we break down!"
+whispered Tom, in short catches between breaths. "I can't stand it much
+longer."
+
+Huckleberry's hard pantings were his only reply, and the boys fixed
+their eyes on the goal of their hopes and bent to their work to win it.
+They gained steadily on it, and at last, breast to breast, they burst
+through the open door and fell grateful and exhausted in the sheltering
+shadows beyond. By and by their pulses slowed down, and Tom whispered:
+
+"Huckleberry, what do you reckon'll come of this?"
+
+"If Doctor Robinson dies, I reckon hanging'll come of it."
+
+"Do you though?"
+
+"Why, I KNOW it, Tom."
+
+Tom thought a while, then he said:
+
+"Who'll tell? We?"
+
+"What are you talking about? S'pose something happened and Injun Joe
+DIDN'T hang? Why, he'd kill us some time or other, just as dead sure as
+we're a laying here."
+
+"That's just what I was thinking to myself, Huck."
+
+"If anybody tells, let Muff Potter do it, if he's fool enough. He's
+generally drunk enough."
+
+Tom said nothing--went on thinking. Presently he whispered:
+
+"Huck, Muff Potter don't know it. How can he tell?"
+
+"What's the reason he don't know it?"
+
+"Because he'd just got that whack when Injun Joe done it. D'you reckon
+he could see anything? D'you reckon he knowed anything?"
+
+"By hokey, that's so, Tom!"
+
+"And besides, look-a-here--maybe that whack done for HIM!"
+
+"No, 'taint likely, Tom. He had liquor in him; I could see that; and
+besides, he always has. Well, when pap's full, you might take and belt
+him over the head with a church and you couldn't phase him. He says so,
+his own self. So it's the same with Muff Potter, of course. But if a
+man was dead sober, I reckon maybe that whack might fetch him; I dono."
+
+After another reflective silence, Tom said:
+
+"Hucky, you sure you can keep mum?"
+
+"Tom, we GOT to keep mum. You know that. That Injun devil wouldn't
+make any more of drownding us than a couple of cats, if we was to
+squeak 'bout this and they didn't hang him. Now, look-a-here, Tom, less
+take and swear to one another--that's what we got to do--swear to keep
+mum."
+
+"I'm agreed. It's the best thing. Would you just hold hands and swear
+that we--"
+
+"Oh no, that wouldn't do for this. That's good enough for little
+rubbishy common things--specially with gals, cuz THEY go back on you
+anyway, and blab if they get in a huff--but there orter be writing
+'bout a big thing like this. And blood."
+
+Tom's whole being applauded this idea. It was deep, and dark, and
+awful; the hour, the circumstances, the surroundings, were in keeping
+with it. He picked up a clean pine shingle that lay in the moonlight,
+took a little fragment of "red keel" out of his pocket, got the moon on
+his work, and painfully scrawled these lines, emphasizing each slow
+down-stroke by clamping his tongue between his teeth, and letting up
+the pressure on the up-strokes. [See next page.]
+
+   "Huck Finn and
+    Tom Sawyer swears
+    they will keep mum
+    about This and They
+    wish They may Drop
+    down dead in Their
+    Tracks if They ever
+    Tell and Rot."
+
+Huckleberry was filled with admiration of Tom's facility in writing,
+and the sublimity of his language. He at once took a pin from his lapel
+and was going to prick his flesh, but Tom said:
+
+"Hold on! Don't do that. A pin's brass. It might have verdigrease on
+it."
+
+"What's verdigrease?"
+
+"It's p'ison. That's what it is. You just swaller some of it once
+--you'll see."
+
+So Tom unwound the thread from one of his needles, and each boy
+pricked the ball of his thumb and squeezed out a drop of blood. In
+time, after many squeezes, Tom managed to sign his initials, using the
+ball of his little finger for a pen. Then he showed Huckleberry how to
+make an H and an F, and the oath was complete. They buried the shingle
+close to the wall, with some dismal ceremonies and incantations, and
+the fetters that bound their tongues were considered to be locked and
+the key thrown away.
+
+A figure crept stealthily through a break in the other end of the
+ruined building, now, but they did not notice it.
+
+"Tom," whispered Huckleberry, "does this keep us from EVER telling
+--ALWAYS?"
+
+"Of course it does. It don't make any difference WHAT happens, we got
+to keep mum. We'd drop down dead--don't YOU know that?"
+
+"Yes, I reckon that's so."
+
+They continued to whisper for some little time. Presently a dog set up
+a long, lugubrious howl just outside--within ten feet of them. The boys
+clasped each other suddenly, in an agony of fright.
+
+"Which of us does he mean?" gasped Huckleberry.
+
+"I dono--peep through the crack. Quick!"
+
+"No, YOU, Tom!"
+
+"I can't--I can't DO it, Huck!"
+
+"Please, Tom. There 'tis again!"
+
+"Oh, lordy, I'm thankful!" whispered Tom. "I know his voice. It's Bull
+Harbison." *
+
+[* If Mr. Harbison owned a slave named Bull, Tom would have spoken of
+him as "Harbison's Bull," but a son or a dog of that name was "Bull
+Harbison."]
+
+"Oh, that's good--I tell you, Tom, I was most scared to death; I'd a
+bet anything it was a STRAY dog."
+
+The dog howled again. The boys' hearts sank once more.
+
+"Oh, my! that ain't no Bull Harbison!" whispered Huckleberry. "DO, Tom!"
+
+Tom, quaking with fear, yielded, and put his eye to the crack. His
+whisper was hardly audible when he said:
+
+"Oh, Huck, IT S A STRAY DOG!"
+
+"Quick, Tom, quick! Who does he mean?"
+
+"Huck, he must mean us both--we're right together."
+
+"Oh, Tom, I reckon we're goners. I reckon there ain't no mistake 'bout
+where I'LL go to. I been so wicked."
+
+"Dad fetch it! This comes of playing hookey and doing everything a
+feller's told NOT to do. I might a been good, like Sid, if I'd a tried
+--but no, I wouldn't, of course. But if ever I get off this time, I lay
+I'll just WALLER in Sunday-schools!" And Tom began to snuffle a little.
+
+"YOU bad!" and Huckleberry began to snuffle too. "Consound it, Tom
+Sawyer, you're just old pie, 'longside o' what I am. Oh, LORDY, lordy,
+lordy, I wisht I only had half your chance."
+
+Tom choked off and whispered:
+
+"Look, Hucky, look! He's got his BACK to us!"
+
+Hucky looked, with joy in his heart.
+
+"Well, he has, by jingoes! Did he before?"
+
+"Yes, he did. But I, like a fool, never thought. Oh, this is bully,
+you know. NOW who can he mean?"
+
+The howling stopped. Tom pricked up his ears.
+
+"Sh! What's that?" he whispered.
+
+"Sounds like--like hogs grunting. No--it's somebody snoring, Tom."
+
+"That IS it! Where 'bouts is it, Huck?"
+
+"I bleeve it's down at 'tother end. Sounds so, anyway. Pap used to
+sleep there, sometimes, 'long with the hogs, but laws bless you, he
+just lifts things when HE snores. Besides, I reckon he ain't ever
+coming back to this town any more."
+
+The spirit of adventure rose in the boys' souls once more.
+
+"Hucky, do you das't to go if I lead?"
+
+"I don't like to, much. Tom, s'pose it's Injun Joe!"
+
+Tom quailed. But presently the temptation rose up strong again and the
+boys agreed to try, with the understanding that they would take to
+their heels if the snoring stopped. So they went tiptoeing stealthily
+down, the one behind the other. When they had got to within five steps
+of the snorer, Tom stepped on a stick, and it broke with a sharp snap.
+The man moaned, writhed a little, and his face came into the moonlight.
+It was Muff Potter. The boys' hearts had stood still, and their hopes
+too, when the man moved, but their fears passed away now. They tiptoed
+out, through the broken weather-boarding, and stopped at a little
+distance to exchange a parting word. That long, lugubrious howl rose on
+the night air again! They turned and saw the strange dog standing
+within a few feet of where Potter was lying, and FACING Potter, with
+his nose pointing heavenward.
+
+"Oh, geeminy, it's HIM!" exclaimed both boys, in a breath.
+
+"Say, Tom--they say a stray dog come howling around Johnny Miller's
+house, 'bout midnight, as much as two weeks ago; and a whippoorwill
+come in and lit on the banisters and sung, the very same evening; and
+there ain't anybody dead there yet."
+
+"Well, I know that. And suppose there ain't. Didn't Gracie Miller fall
+in the kitchen fire and burn herself terrible the very next Saturday?"
+
+"Yes, but she ain't DEAD. And what's more, she's getting better, too."
+
+"All right, you wait and see. She's a goner, just as dead sure as Muff
+Potter's a goner. That's what the niggers say, and they know all about
+these kind of things, Huck."
+
+Then they separated, cogitating. When Tom crept in at his bedroom
+window the night was almost spent. He undressed with excessive caution,
+and fell asleep congratulating himself that nobody knew of his
+escapade. He was not aware that the gently-snoring Sid was awake, and
+had been so for an hour.
+
+When Tom awoke, Sid was dressed and gone. There was a late look in the
+light, a late sense in the atmosphere. He was startled. Why had he not
+been called--persecuted till he was up, as usual? The thought filled
+him with bodings. Within five minutes he was dressed and down-stairs,
+feeling sore and drowsy. The family were still at table, but they had
+finished breakfast. There was no voice of rebuke; but there were
+averted eyes; there was a silence and an air of solemnity that struck a
+chill to the culprit's heart. He sat down and tried to seem gay, but it
+was up-hill work; it roused no smile, no response, and he lapsed into
+silence and let his heart sink down to the depths.
+
+After breakfast his aunt took him aside, and Tom almost brightened in
+the hope that he was going to be flogged; but it was not so. His aunt
+wept over him and asked him how he could go and break her old heart so;
+and finally told him to go on, and ruin himself and bring her gray
+hairs with sorrow to the grave, for it was no use for her to try any
+more. This was worse than a thousand whippings, and Tom's heart was
+sorer now than his body. He cried, he pleaded for forgiveness, promised
+to reform over and over again, and then received his dismissal, feeling
+that he had won but an imperfect forgiveness and established but a
+feeble confidence.
+
+He left the presence too miserable to even feel revengeful toward Sid;
+and so the latter's prompt retreat through the back gate was
+unnecessary. He moped to school gloomy and sad, and took his flogging,
+along with Joe Harper, for playing hookey the day before, with the air
+of one whose heart was busy with heavier woes and wholly dead to
+trifles. Then he betook himself to his seat, rested his elbows on his
+desk and his jaws in his hands, and stared at the wall with the stony
+stare of suffering that has reached the limit and can no further go.
+His elbow was pressing against some hard substance. After a long time
+he slowly and sadly changed his position, and took up this object with
+a sigh. It was in a paper. He unrolled it. A long, lingering, colossal
+sigh followed, and his heart broke. It was his brass andiron knob!
+
+This final feather broke the camel's back.
+
+
+
+CHAPTER XI
+
+CLOSE upon the hour of noon the whole village was suddenly electrified
+with the ghastly news. No need of the as yet undreamed-of telegraph;
+the tale flew from man to man, from group to group, from house to
+house, with little less than telegraphic speed. Of course the
+schoolmaster gave holiday for that afternoon; the town would have
+thought strangely of him if he had not.
+
+A gory knife had been found close to the murdered man, and it had been
+recognized by somebody as belonging to Muff Potter--so the story ran.
+And it was said that a belated citizen had come upon Potter washing
+himself in the "branch" about one or two o'clock in the morning, and
+that Potter had at once sneaked off--suspicious circumstances,
+especially the washing which was not a habit with Potter. It was also
+said that the town had been ransacked for this "murderer" (the public
+are not slow in the matter of sifting evidence and arriving at a
+verdict), but that he could not be found. Horsemen had departed down
+all the roads in every direction, and the Sheriff "was confident" that
+he would be captured before night.
+
+All the town was drifting toward the graveyard. Tom's heartbreak
+vanished and he joined the procession, not because he would not a
+thousand times rather go anywhere else, but because an awful,
+unaccountable fascination drew him on. Arrived at the dreadful place,
+he wormed his small body through the crowd and saw the dismal
+spectacle. It seemed to him an age since he was there before. Somebody
+pinched his arm. He turned, and his eyes met Huckleberry's. Then both
+looked elsewhere at once, and wondered if anybody had noticed anything
+in their mutual glance. But everybody was talking, and intent upon the
+grisly spectacle before them.
+
+"Poor fellow!" "Poor young fellow!" "This ought to be a lesson to
+grave robbers!" "Muff Potter'll hang for this if they catch him!" This
+was the drift of remark; and the minister said, "It was a judgment; His
+hand is here."
+
+Now Tom shivered from head to heel; for his eye fell upon the stolid
+face of Injun Joe. At this moment the crowd began to sway and struggle,
+and voices shouted, "It's him! it's him! he's coming himself!"
+
+"Who? Who?" from twenty voices.
+
+"Muff Potter!"
+
+"Hallo, he's stopped!--Look out, he's turning! Don't let him get away!"
+
+People in the branches of the trees over Tom's head said he wasn't
+trying to get away--he only looked doubtful and perplexed.
+
+"Infernal impudence!" said a bystander; "wanted to come and take a
+quiet look at his work, I reckon--didn't expect any company."
+
+The crowd fell apart, now, and the Sheriff came through,
+ostentatiously leading Potter by the arm. The poor fellow's face was
+haggard, and his eyes showed the fear that was upon him. When he stood
+before the murdered man, he shook as with a palsy, and he put his face
+in his hands and burst into tears.
+
+"I didn't do it, friends," he sobbed; "'pon my word and honor I never
+done it."
+
+"Who's accused you?" shouted a voice.
+
+This shot seemed to carry home. Potter lifted his face and looked
+around him with a pathetic hopelessness in his eyes. He saw Injun Joe,
+and exclaimed:
+
+"Oh, Injun Joe, you promised me you'd never--"
+
+"Is that your knife?" and it was thrust before him by the Sheriff.
+
+Potter would have fallen if they had not caught him and eased him to
+the ground. Then he said:
+
+"Something told me 't if I didn't come back and get--" He shuddered;
+then waved his nerveless hand with a vanquished gesture and said, "Tell
+'em, Joe, tell 'em--it ain't any use any more."
+
+Then Huckleberry and Tom stood dumb and staring, and heard the
+stony-hearted liar reel off his serene statement, they expecting every
+moment that the clear sky would deliver God's lightnings upon his head,
+and wondering to see how long the stroke was delayed. And when he had
+finished and still stood alive and whole, their wavering impulse to
+break their oath and save the poor betrayed prisoner's life faded and
+vanished away, for plainly this miscreant had sold himself to Satan and
+it would be fatal to meddle with the property of such a power as that.
+
+"Why didn't you leave? What did you want to come here for?" somebody
+said.
+
+"I couldn't help it--I couldn't help it," Potter moaned. "I wanted to
+run away, but I couldn't seem to come anywhere but here." And he fell
+to sobbing again.
+
+Injun Joe repeated his statement, just as calmly, a few minutes
+afterward on the inquest, under oath; and the boys, seeing that the
+lightnings were still withheld, were confirmed in their belief that Joe
+had sold himself to the devil. He was now become, to them, the most
+balefully interesting object they had ever looked upon, and they could
+not take their fascinated eyes from his face.
+
+They inwardly resolved to watch him nights, when opportunity should
+offer, in the hope of getting a glimpse of his dread master.
+
+Injun Joe helped to raise the body of the murdered man and put it in a
+wagon for removal; and it was whispered through the shuddering crowd
+that the wound bled a little! The boys thought that this happy
+circumstance would turn suspicion in the right direction; but they were
+disappointed, for more than one villager remarked:
+
+"It was within three feet of Muff Potter when it done it."
+
+Tom's fearful secret and gnawing conscience disturbed his sleep for as
+much as a week after this; and at breakfast one morning Sid said:
+
+"Tom, you pitch around and talk in your sleep so much that you keep me
+awake half the time."
+
+Tom blanched and dropped his eyes.
+
+"It's a bad sign," said Aunt Polly, gravely. "What you got on your
+mind, Tom?"
+
+"Nothing. Nothing 't I know of." But the boy's hand shook so that he
+spilled his coffee.
+
+"And you do talk such stuff," Sid said. "Last night you said, 'It's
+blood, it's blood, that's what it is!' You said that over and over. And
+you said, 'Don't torment me so--I'll tell!' Tell WHAT? What is it
+you'll tell?"
+
+Everything was swimming before Tom. There is no telling what might
+have happened, now, but luckily the concern passed out of Aunt Polly's
+face and she came to Tom's relief without knowing it. She said:
+
+"Sho! It's that dreadful murder. I dream about it most every night
+myself. Sometimes I dream it's me that done it."
+
+Mary said she had been affected much the same way. Sid seemed
+satisfied. Tom got out of the presence as quick as he plausibly could,
+and after that he complained of toothache for a week, and tied up his
+jaws every night. He never knew that Sid lay nightly watching, and
+frequently slipped the bandage free and then leaned on his elbow
+listening a good while at a time, and afterward slipped the bandage
+back to its place again. Tom's distress of mind wore off gradually and
+the toothache grew irksome and was discarded. If Sid really managed to
+make anything out of Tom's disjointed mutterings, he kept it to himself.
+
+It seemed to Tom that his schoolmates never would get done holding
+inquests on dead cats, and thus keeping his trouble present to his
+mind. Sid noticed that Tom never was coroner at one of these inquiries,
+though it had been his habit to take the lead in all new enterprises;
+he noticed, too, that Tom never acted as a witness--and that was
+strange; and Sid did not overlook the fact that Tom even showed a
+marked aversion to these inquests, and always avoided them when he
+could. Sid marvelled, but said nothing. However, even inquests went out
+of vogue at last, and ceased to torture Tom's conscience.
+
+Every day or two, during this time of sorrow, Tom watched his
+opportunity and went to the little grated jail-window and smuggled such
+small comforts through to the "murderer" as he could get hold of. The
+jail was a trifling little brick den that stood in a marsh at the edge
+of the village, and no guards were afforded for it; indeed, it was
+seldom occupied. These offerings greatly helped to ease Tom's
+conscience.
+
+The villagers had a strong desire to tar-and-feather Injun Joe and
+ride him on a rail, for body-snatching, but so formidable was his
+character that nobody could be found who was willing to take the lead
+in the matter, so it was dropped. He had been careful to begin both of
+his inquest-statements with the fight, without confessing the
+grave-robbery that preceded it; therefore it was deemed wisest not
+to try the case in the courts at present.
+
+
+
+CHAPTER XII
+
+ONE of the reasons why Tom's mind had drifted away from its secret
+troubles was, that it had found a new and weighty matter to interest
+itself about. Becky Thatcher had stopped coming to school. Tom had
+struggled with his pride a few days, and tried to "whistle her down the
+wind," but failed. He began to find himself hanging around her father's
+house, nights, and feeling very miserable. She was ill. What if she
+should die! There was distraction in the thought. He no longer took an
+interest in war, nor even in piracy. The charm of life was gone; there
+was nothing but dreariness left. He put his hoop away, and his bat;
+there was no joy in them any more. His aunt was concerned. She began to
+try all manner of remedies on him. She was one of those people who are
+infatuated with patent medicines and all new-fangled methods of
+producing health or mending it. She was an inveterate experimenter in
+these things. When something fresh in this line came out she was in a
+fever, right away, to try it; not on herself, for she was never ailing,
+but on anybody else that came handy. She was a subscriber for all the
+"Health" periodicals and phrenological frauds; and the solemn ignorance
+they were inflated with was breath to her nostrils. All the "rot" they
+contained about ventilation, and how to go to bed, and how to get up,
+and what to eat, and what to drink, and how much exercise to take, and
+what frame of mind to keep one's self in, and what sort of clothing to
+wear, was all gospel to her, and she never observed that her
+health-journals of the current month customarily upset everything they
+had recommended the month before. She was as simple-hearted and honest
+as the day was long, and so she was an easy victim. She gathered
+together her quack periodicals and her quack medicines, and thus armed
+with death, went about on her pale horse, metaphorically speaking, with
+"hell following after." But she never suspected that she was not an
+angel of healing and the balm of Gilead in disguise, to the suffering
+neighbors.
+
+The water treatment was new, now, and Tom's low condition was a
+windfall to her. She had him out at daylight every morning, stood him
+up in the woodshed and drowned him with a deluge of cold water; then
+she scrubbed him down with a towel like a file, and so brought him to;
+then she rolled him up in a wet sheet and put him away under blankets
+till she sweated his soul clean and "the yellow stains of it came
+through his pores"--as Tom said.
+
+Yet notwithstanding all this, the boy grew more and more melancholy
+and pale and dejected. She added hot baths, sitz baths, shower baths,
+and plunges. The boy remained as dismal as a hearse. She began to
+assist the water with a slim oatmeal diet and blister-plasters. She
+calculated his capacity as she would a jug's, and filled him up every
+day with quack cure-alls.
+
+Tom had become indifferent to persecution by this time. This phase
+filled the old lady's heart with consternation. This indifference must
+be broken up at any cost. Now she heard of Pain-killer for the first
+time. She ordered a lot at once. She tasted it and was filled with
+gratitude. It was simply fire in a liquid form. She dropped the water
+treatment and everything else, and pinned her faith to Pain-killer. She
+gave Tom a teaspoonful and watched with the deepest anxiety for the
+result. Her troubles were instantly at rest, her soul at peace again;
+for the "indifference" was broken up. The boy could not have shown a
+wilder, heartier interest, if she had built a fire under him.
+
+Tom felt that it was time to wake up; this sort of life might be
+romantic enough, in his blighted condition, but it was getting to have
+too little sentiment and too much distracting variety about it. So he
+thought over various plans for relief, and finally hit pon that of
+professing to be fond of Pain-killer. He asked for it so often that he
+became a nuisance, and his aunt ended by telling him to help himself
+and quit bothering her. If it had been Sid, she would have had no
+misgivings to alloy her delight; but since it was Tom, she watched the
+bottle clandestinely. She found that the medicine did really diminish,
+but it did not occur to her that the boy was mending the health of a
+crack in the sitting-room floor with it.
+
+One day Tom was in the act of dosing the crack when his aunt's yellow
+cat came along, purring, eying the teaspoon avariciously, and begging
+for a taste. Tom said:
+
+"Don't ask for it unless you want it, Peter."
+
+But Peter signified that he did want it.
+
+"You better make sure."
+
+Peter was sure.
+
+"Now you've asked for it, and I'll give it to you, because there ain't
+anything mean about me; but if you find you don't like it, you mustn't
+blame anybody but your own self."
+
+Peter was agreeable. So Tom pried his mouth open and poured down the
+Pain-killer. Peter sprang a couple of yards in the air, and then
+delivered a war-whoop and set off round and round the room, banging
+against furniture, upsetting flower-pots, and making general havoc.
+Next he rose on his hind feet and pranced around, in a frenzy of
+enjoyment, with his head over his shoulder and his voice proclaiming
+his unappeasable happiness. Then he went tearing around the house again
+spreading chaos and destruction in his path. Aunt Polly entered in time
+to see him throw a few double summersets, deliver a final mighty
+hurrah, and sail through the open window, carrying the rest of the
+flower-pots with him. The old lady stood petrified with astonishment,
+peering over her glasses; Tom lay on the floor expiring with laughter.
+
+"Tom, what on earth ails that cat?"
+
+"I don't know, aunt," gasped the boy.
+
+"Why, I never see anything like it. What did make him act so?"
+
+"Deed I don't know, Aunt Polly; cats always act so when they're having
+a good time."
+
+"They do, do they?" There was something in the tone that made Tom
+apprehensive.
+
+"Yes'm. That is, I believe they do."
+
+"You DO?"
+
+"Yes'm."
+
+The old lady was bending down, Tom watching, with interest emphasized
+by anxiety. Too late he divined her "drift." The handle of the telltale
+teaspoon was visible under the bed-valance. Aunt Polly took it, held it
+up. Tom winced, and dropped his eyes. Aunt Polly raised him by the
+usual handle--his ear--and cracked his head soundly with her thimble.
+
+"Now, sir, what did you want to treat that poor dumb beast so, for?"
+
+"I done it out of pity for him--because he hadn't any aunt."
+
+"Hadn't any aunt!--you numskull. What has that got to do with it?"
+
+"Heaps. Because if he'd had one she'd a burnt him out herself! She'd a
+roasted his bowels out of him 'thout any more feeling than if he was a
+human!"
+
+Aunt Polly felt a sudden pang of remorse. This was putting the thing
+in a new light; what was cruelty to a cat MIGHT be cruelty to a boy,
+too. She began to soften; she felt sorry. Her eyes watered a little,
+and she put her hand on Tom's head and said gently:
+
+"I was meaning for the best, Tom. And, Tom, it DID do you good."
+
+Tom looked up in her face with just a perceptible twinkle peeping
+through his gravity.
+
+"I know you was meaning for the best, aunty, and so was I with Peter.
+It done HIM good, too. I never see him get around so since--"
+
+"Oh, go 'long with you, Tom, before you aggravate me again. And you
+try and see if you can't be a good boy, for once, and you needn't take
+any more medicine."
+
+Tom reached school ahead of time. It was noticed that this strange
+thing had been occurring every day latterly. And now, as usual of late,
+he hung about the gate of the schoolyard instead of playing with his
+comrades. He was sick, he said, and he looked it. He tried to seem to
+be looking everywhere but whither he really was looking--down the road.
+Presently Jeff Thatcher hove in sight, and Tom's face lighted; he gazed
+a moment, and then turned sorrowfully away. When Jeff arrived, Tom
+accosted him; and "led up" warily to opportunities for remark about
+Becky, but the giddy lad never could see the bait. Tom watched and
+watched, hoping whenever a frisking frock came in sight, and hating the
+owner of it as soon as he saw she was not the right one. At last frocks
+ceased to appear, and he dropped hopelessly into the dumps; he entered
+the empty schoolhouse and sat down to suffer. Then one more frock
+passed in at the gate, and Tom's heart gave a great bound. The next
+instant he was out, and "going on" like an Indian; yelling, laughing,
+chasing boys, jumping over the fence at risk of life and limb, throwing
+handsprings, standing on his head--doing all the heroic things he could
+conceive of, and keeping a furtive eye out, all the while, to see if
+Becky Thatcher was noticing. But she seemed to be unconscious of it
+all; she never looked. Could it be possible that she was not aware that
+he was there? He carried his exploits to her immediate vicinity; came
+war-whooping around, snatched a boy's cap, hurled it to the roof of the
+schoolhouse, broke through a group of boys, tumbling them in every
+direction, and fell sprawling, himself, under Becky's nose, almost
+upsetting her--and she turned, with her nose in the air, and he heard
+her say: "Mf! some people think they're mighty smart--always showing
+off!"
+
+Tom's cheeks burned. He gathered himself up and sneaked off, crushed
+and crestfallen.
+
+
+
+CHAPTER XIII
+
+TOM'S mind was made up now. He was gloomy and desperate. He was a
+forsaken, friendless boy, he said; nobody loved him; when they found
+out what they had driven him to, perhaps they would be sorry; he had
+tried to do right and get along, but they would not let him; since
+nothing would do them but to be rid of him, let it be so; and let them
+blame HIM for the consequences--why shouldn't they? What right had the
+friendless to complain? Yes, they had forced him to it at last: he
+would lead a life of crime. There was no choice.
+
+By this time he was far down Meadow Lane, and the bell for school to
+"take up" tinkled faintly upon his ear. He sobbed, now, to think he
+should never, never hear that old familiar sound any more--it was very
+hard, but it was forced on him; since he was driven out into the cold
+world, he must submit--but he forgave them. Then the sobs came thick
+and fast.
+
+Just at this point he met his soul's sworn comrade, Joe Harper
+--hard-eyed, and with evidently a great and dismal purpose in his heart.
+Plainly here were "two souls with but a single thought." Tom, wiping
+his eyes with his sleeve, began to blubber out something about a
+resolution to escape from hard usage and lack of sympathy at home by
+roaming abroad into the great world never to return; and ended by
+hoping that Joe would not forget him.
+
+But it transpired that this was a request which Joe had just been
+going to make of Tom, and had come to hunt him up for that purpose. His
+mother had whipped him for drinking some cream which he had never
+tasted and knew nothing about; it was plain that she was tired of him
+and wished him to go; if she felt that way, there was nothing for him
+to do but succumb; he hoped she would be happy, and never regret having
+driven her poor boy out into the unfeeling world to suffer and die.
+
+As the two boys walked sorrowing along, they made a new compact to
+stand by each other and be brothers and never separate till death
+relieved them of their troubles. Then they began to lay their plans.
+Joe was for being a hermit, and living on crusts in a remote cave, and
+dying, some time, of cold and want and grief; but after listening to
+Tom, he conceded that there were some conspicuous advantages about a
+life of crime, and so he consented to be a pirate.
+
+Three miles below St. Petersburg, at a point where the Mississippi
+River was a trifle over a mile wide, there was a long, narrow, wooded
+island, with a shallow bar at the head of it, and this offered well as
+a rendezvous. It was not inhabited; it lay far over toward the further
+shore, abreast a dense and almost wholly unpeopled forest. So Jackson's
+Island was chosen. Who were to be the subjects of their piracies was a
+matter that did not occur to them. Then they hunted up Huckleberry
+Finn, and he joined them promptly, for all careers were one to him; he
+was indifferent. They presently separated to meet at a lonely spot on
+the river-bank two miles above the village at the favorite hour--which
+was midnight. There was a small log raft there which they meant to
+capture. Each would bring hooks and lines, and such provision as he
+could steal in the most dark and mysterious way--as became outlaws. And
+before the afternoon was done, they had all managed to enjoy the sweet
+glory of spreading the fact that pretty soon the town would "hear
+something." All who got this vague hint were cautioned to "be mum and
+wait."
+
+About midnight Tom arrived with a boiled ham and a few trifles,
+and stopped in a dense undergrowth on a small bluff overlooking the
+meeting-place. It was starlight, and very still. The mighty river lay
+like an ocean at rest. Tom listened a moment, but no sound disturbed the
+quiet. Then he gave a low, distinct whistle. It was answered from under
+the bluff. Tom whistled twice more; these signals were answered in the
+same way. Then a guarded voice said:
+
+"Who goes there?"
+
+"Tom Sawyer, the Black Avenger of the Spanish Main. Name your names."
+
+"Huck Finn the Red-Handed, and Joe Harper the Terror of the Seas." Tom
+had furnished these titles, from his favorite literature.
+
+"'Tis well. Give the countersign."
+
+Two hoarse whispers delivered the same awful word simultaneously to
+the brooding night:
+
+"BLOOD!"
+
+Then Tom tumbled his ham over the bluff and let himself down after it,
+tearing both skin and clothes to some extent in the effort. There was
+an easy, comfortable path along the shore under the bluff, but it
+lacked the advantages of difficulty and danger so valued by a pirate.
+
+The Terror of the Seas had brought a side of bacon, and had about worn
+himself out with getting it there. Finn the Red-Handed had stolen a
+skillet and a quantity of half-cured leaf tobacco, and had also brought
+a few corn-cobs to make pipes with. But none of the pirates smoked or
+"chewed" but himself. The Black Avenger of the Spanish Main said it
+would never do to start without some fire. That was a wise thought;
+matches were hardly known there in that day. They saw a fire
+smouldering upon a great raft a hundred yards above, and they went
+stealthily thither and helped themselves to a chunk. They made an
+imposing adventure of it, saying, "Hist!" every now and then, and
+suddenly halting with finger on lip; moving with hands on imaginary
+dagger-hilts; and giving orders in dismal whispers that if "the foe"
+stirred, to "let him have it to the hilt," because "dead men tell no
+tales." They knew well enough that the raftsmen were all down at the
+village laying in stores or having a spree, but still that was no
+excuse for their conducting this thing in an unpiratical way.
+
+They shoved off, presently, Tom in command, Huck at the after oar and
+Joe at the forward. Tom stood amidships, gloomy-browed, and with folded
+arms, and gave his orders in a low, stern whisper:
+
+"Luff, and bring her to the wind!"
+
+"Aye-aye, sir!"
+
+"Steady, steady-y-y-y!"
+
+"Steady it is, sir!"
+
+"Let her go off a point!"
+
+"Point it is, sir!"
+
+As the boys steadily and monotonously drove the raft toward mid-stream
+it was no doubt understood that these orders were given only for
+"style," and were not intended to mean anything in particular.
+
+"What sail's she carrying?"
+
+"Courses, tops'ls, and flying-jib, sir."
+
+"Send the r'yals up! Lay out aloft, there, half a dozen of ye
+--foretopmaststuns'l! Lively, now!"
+
+"Aye-aye, sir!"
+
+"Shake out that maintogalans'l! Sheets and braces! NOW my hearties!"
+
+"Aye-aye, sir!"
+
+"Hellum-a-lee--hard a port! Stand by to meet her when she comes! Port,
+port! NOW, men! With a will! Stead-y-y-y!"
+
+"Steady it is, sir!"
+
+The raft drew beyond the middle of the river; the boys pointed her
+head right, and then lay on their oars. The river was not high, so
+there was not more than a two or three mile current. Hardly a word was
+said during the next three-quarters of an hour. Now the raft was
+passing before the distant town. Two or three glimmering lights showed
+where it lay, peacefully sleeping, beyond the vague vast sweep of
+star-gemmed water, unconscious of the tremendous event that was happening.
+The Black Avenger stood still with folded arms, "looking his last" upon
+the scene of his former joys and his later sufferings, and wishing
+"she" could see him now, abroad on the wild sea, facing peril and death
+with dauntless heart, going to his doom with a grim smile on his lips.
+It was but a small strain on his imagination to remove Jackson's Island
+beyond eyeshot of the village, and so he "looked his last" with a
+broken and satisfied heart. The other pirates were looking their last,
+too; and they all looked so long that they came near letting the
+current drift them out of the range of the island. But they discovered
+the danger in time, and made shift to avert it. About two o'clock in
+the morning the raft grounded on the bar two hundred yards above the
+head of the island, and they waded back and forth until they had landed
+their freight. Part of the little raft's belongings consisted of an old
+sail, and this they spread over a nook in the bushes for a tent to
+shelter their provisions; but they themselves would sleep in the open
+air in good weather, as became outlaws.
+
+They built a fire against the side of a great log twenty or thirty
+steps within the sombre depths of the forest, and then cooked some
+bacon in the frying-pan for supper, and used up half of the corn "pone"
+stock they had brought. It seemed glorious sport to be feasting in that
+wild, free way in the virgin forest of an unexplored and uninhabited
+island, far from the haunts of men, and they said they never would
+return to civilization. The climbing fire lit up their faces and threw
+its ruddy glare upon the pillared tree-trunks of their forest temple,
+and upon the varnished foliage and festooning vines.
+
+When the last crisp slice of bacon was gone, and the last allowance of
+corn pone devoured, the boys stretched themselves out on the grass,
+filled with contentment. They could have found a cooler place, but they
+would not deny themselves such a romantic feature as the roasting
+camp-fire.
+
+"AIN'T it gay?" said Joe.
+
+"It's NUTS!" said Tom. "What would the boys say if they could see us?"
+
+"Say? Well, they'd just die to be here--hey, Hucky!"
+
+"I reckon so," said Huckleberry; "anyways, I'm suited. I don't want
+nothing better'n this. I don't ever get enough to eat, gen'ally--and
+here they can't come and pick at a feller and bullyrag him so."
+
+"It's just the life for me," said Tom. "You don't have to get up,
+mornings, and you don't have to go to school, and wash, and all that
+blame foolishness. You see a pirate don't have to do ANYTHING, Joe,
+when he's ashore, but a hermit HE has to be praying considerable, and
+then he don't have any fun, anyway, all by himself that way."
+
+"Oh yes, that's so," said Joe, "but I hadn't thought much about it,
+you know. I'd a good deal rather be a pirate, now that I've tried it."
+
+"You see," said Tom, "people don't go much on hermits, nowadays, like
+they used to in old times, but a pirate's always respected. And a
+hermit's got to sleep on the hardest place he can find, and put
+sackcloth and ashes on his head, and stand out in the rain, and--"
+
+"What does he put sackcloth and ashes on his head for?" inquired Huck.
+
+"I dono. But they've GOT to do it. Hermits always do. You'd have to do
+that if you was a hermit."
+
+"Dern'd if I would," said Huck.
+
+"Well, what would you do?"
+
+"I dono. But I wouldn't do that."
+
+"Why, Huck, you'd HAVE to. How'd you get around it?"
+
+"Why, I just wouldn't stand it. I'd run away."
+
+"Run away! Well, you WOULD be a nice old slouch of a hermit. You'd be
+a disgrace."
+
+The Red-Handed made no response, being better employed. He had
+finished gouging out a cob, and now he fitted a weed stem to it, loaded
+it with tobacco, and was pressing a coal to the charge and blowing a
+cloud of fragrant smoke--he was in the full bloom of luxurious
+contentment. The other pirates envied him this majestic vice, and
+secretly resolved to acquire it shortly. Presently Huck said:
+
+"What does pirates have to do?"
+
+Tom said:
+
+"Oh, they have just a bully time--take ships and burn them, and get
+the money and bury it in awful places in their island where there's
+ghosts and things to watch it, and kill everybody in the ships--make
+'em walk a plank."
+
+"And they carry the women to the island," said Joe; "they don't kill
+the women."
+
+"No," assented Tom, "they don't kill the women--they're too noble. And
+the women's always beautiful, too.
+
+"And don't they wear the bulliest clothes! Oh no! All gold and silver
+and di'monds," said Joe, with enthusiasm.
+
+"Who?" said Huck.
+
+"Why, the pirates."
+
+Huck scanned his own clothing forlornly.
+
+"I reckon I ain't dressed fitten for a pirate," said he, with a
+regretful pathos in his voice; "but I ain't got none but these."
+
+But the other boys told him the fine clothes would come fast enough,
+after they should have begun their adventures. They made him understand
+that his poor rags would do to begin with, though it was customary for
+wealthy pirates to start with a proper wardrobe.
+
+Gradually their talk died out and drowsiness began to steal upon the
+eyelids of the little waifs. The pipe dropped from the fingers of the
+Red-Handed, and he slept the sleep of the conscience-free and the
+weary. The Terror of the Seas and the Black Avenger of the Spanish Main
+had more difficulty in getting to sleep. They said their prayers
+inwardly, and lying down, since there was nobody there with authority
+to make them kneel and recite aloud; in truth, they had a mind not to
+say them at all, but they were afraid to proceed to such lengths as
+that, lest they might call down a sudden and special thunderbolt from
+heaven. Then at once they reached and hovered upon the imminent verge
+of sleep--but an intruder came, now, that would not "down." It was
+conscience. They began to feel a vague fear that they had been doing
+wrong to run away; and next they thought of the stolen meat, and then
+the real torture came. They tried to argue it away by reminding
+conscience that they had purloined sweetmeats and apples scores of
+times; but conscience was not to be appeased by such thin
+plausibilities; it seemed to them, in the end, that there was no
+getting around the stubborn fact that taking sweetmeats was only
+"hooking," while taking bacon and hams and such valuables was plain
+simple stealing--and there was a command against that in the Bible. So
+they inwardly resolved that so long as they remained in the business,
+their piracies should not again be sullied with the crime of stealing.
+Then conscience granted a truce, and these curiously inconsistent
+pirates fell peacefully to sleep.
+
+
+
+CHAPTER XIV
+
+WHEN Tom awoke in the morning, he wondered where he was. He sat up and
+rubbed his eyes and looked around. Then he comprehended. It was the
+cool gray dawn, and there was a delicious sense of repose and peace in
+the deep pervading calm and silence of the woods. Not a leaf stirred;
+not a sound obtruded upon great Nature's meditation. Beaded dewdrops
+stood upon the leaves and grasses. A white layer of ashes covered the
+fire, and a thin blue breath of smoke rose straight into the air. Joe
+and Huck still slept.
+
+Now, far away in the woods a bird called; another answered; presently
+the hammering of a woodpecker was heard. Gradually the cool dim gray of
+the morning whitened, and as gradually sounds multiplied and life
+manifested itself. The marvel of Nature shaking off sleep and going to
+work unfolded itself to the musing boy. A little green worm came
+crawling over a dewy leaf, lifting two-thirds of his body into the air
+from time to time and "sniffing around," then proceeding again--for he
+was measuring, Tom said; and when the worm approached him, of its own
+accord, he sat as still as a stone, with his hopes rising and falling,
+by turns, as the creature still came toward him or seemed inclined to
+go elsewhere; and when at last it considered a painful moment with its
+curved body in the air and then came decisively down upon Tom's leg and
+began a journey over him, his whole heart was glad--for that meant that
+he was going to have a new suit of clothes--without the shadow of a
+doubt a gaudy piratical uniform. Now a procession of ants appeared,
+from nowhere in particular, and went about their labors; one struggled
+manfully by with a dead spider five times as big as itself in its arms,
+and lugged it straight up a tree-trunk. A brown spotted lady-bug
+climbed the dizzy height of a grass blade, and Tom bent down close to
+it and said, "Lady-bug, lady-bug, fly away home, your house is on fire,
+your children's alone," and she took wing and went off to see about it
+--which did not surprise the boy, for he knew of old that this insect was
+credulous about conflagrations, and he had practised upon its
+simplicity more than once. A tumblebug came next, heaving sturdily at
+its ball, and Tom touched the creature, to see it shut its legs against
+its body and pretend to be dead. The birds were fairly rioting by this
+time. A catbird, the Northern mocker, lit in a tree over Tom's head,
+and trilled out her imitations of her neighbors in a rapture of
+enjoyment; then a shrill jay swept down, a flash of blue flame, and
+stopped on a twig almost within the boy's reach, cocked his head to one
+side and eyed the strangers with a consuming curiosity; a gray squirrel
+and a big fellow of the "fox" kind came skurrying along, sitting up at
+intervals to inspect and chatter at the boys, for the wild things had
+probably never seen a human being before and scarcely knew whether to
+be afraid or not. All Nature was wide awake and stirring, now; long
+lances of sunlight pierced down through the dense foliage far and near,
+and a few butterflies came fluttering upon the scene.
+
+Tom stirred up the other pirates and they all clattered away with a
+shout, and in a minute or two were stripped and chasing after and
+tumbling over each other in the shallow limpid water of the white
+sandbar. They felt no longing for the little village sleeping in the
+distance beyond the majestic waste of water. A vagrant current or a
+slight rise in the river had carried off their raft, but this only
+gratified them, since its going was something like burning the bridge
+between them and civilization.
+
+They came back to camp wonderfully refreshed, glad-hearted, and
+ravenous; and they soon had the camp-fire blazing up again. Huck found
+a spring of clear cold water close by, and the boys made cups of broad
+oak or hickory leaves, and felt that water, sweetened with such a
+wildwood charm as that, would be a good enough substitute for coffee.
+While Joe was slicing bacon for breakfast, Tom and Huck asked him to
+hold on a minute; they stepped to a promising nook in the river-bank
+and threw in their lines; almost immediately they had reward. Joe had
+not had time to get impatient before they were back again with some
+handsome bass, a couple of sun-perch and a small catfish--provisions
+enough for quite a family. They fried the fish with the bacon, and were
+astonished; for no fish had ever seemed so delicious before. They did
+not know that the quicker a fresh-water fish is on the fire after he is
+caught the better he is; and they reflected little upon what a sauce
+open-air sleeping, open-air exercise, bathing, and a large ingredient
+of hunger make, too.
+
+They lay around in the shade, after breakfast, while Huck had a smoke,
+and then went off through the woods on an exploring expedition. They
+tramped gayly along, over decaying logs, through tangled underbrush,
+among solemn monarchs of the forest, hung from their crowns to the
+ground with a drooping regalia of grape-vines. Now and then they came
+upon snug nooks carpeted with grass and jeweled with flowers.
+
+They found plenty of things to be delighted with, but nothing to be
+astonished at. They discovered that the island was about three miles
+long and a quarter of a mile wide, and that the shore it lay closest to
+was only separated from it by a narrow channel hardly two hundred yards
+wide. They took a swim about every hour, so it was close upon the
+middle of the afternoon when they got back to camp. They were too
+hungry to stop to fish, but they fared sumptuously upon cold ham, and
+then threw themselves down in the shade to talk. But the talk soon
+began to drag, and then died. The stillness, the solemnity that brooded
+in the woods, and the sense of loneliness, began to tell upon the
+spirits of the boys. They fell to thinking. A sort of undefined longing
+crept upon them. This took dim shape, presently--it was budding
+homesickness. Even Finn the Red-Handed was dreaming of his doorsteps
+and empty hogsheads. But they were all ashamed of their weakness, and
+none was brave enough to speak his thought.
+
+For some time, now, the boys had been dully conscious of a peculiar
+sound in the distance, just as one sometimes is of the ticking of a
+clock which he takes no distinct note of. But now this mysterious sound
+became more pronounced, and forced a recognition. The boys started,
+glanced at each other, and then each assumed a listening attitude.
+There was a long silence, profound and unbroken; then a deep, sullen
+boom came floating down out of the distance.
+
+"What is it!" exclaimed Joe, under his breath.
+
+"I wonder," said Tom in a whisper.
+
+"'Tain't thunder," said Huckleberry, in an awed tone, "becuz thunder--"
+
+"Hark!" said Tom. "Listen--don't talk."
+
+They waited a time that seemed an age, and then the same muffled boom
+troubled the solemn hush.
+
+"Let's go and see."
+
+They sprang to their feet and hurried to the shore toward the town.
+They parted the bushes on the bank and peered out over the water. The
+little steam ferryboat was about a mile below the village, drifting
+with the current. Her broad deck seemed crowded with people. There were
+a great many skiffs rowing about or floating with the stream in the
+neighborhood of the ferryboat, but the boys could not determine what
+the men in them were doing. Presently a great jet of white smoke burst
+from the ferryboat's side, and as it expanded and rose in a lazy cloud,
+that same dull throb of sound was borne to the listeners again.
+
+"I know now!" exclaimed Tom; "somebody's drownded!"
+
+"That's it!" said Huck; "they done that last summer, when Bill Turner
+got drownded; they shoot a cannon over the water, and that makes him
+come up to the top. Yes, and they take loaves of bread and put
+quicksilver in 'em and set 'em afloat, and wherever there's anybody
+that's drownded, they'll float right there and stop."
+
+"Yes, I've heard about that," said Joe. "I wonder what makes the bread
+do that."
+
+"Oh, it ain't the bread, so much," said Tom; "I reckon it's mostly
+what they SAY over it before they start it out."
+
+"But they don't say anything over it," said Huck. "I've seen 'em and
+they don't."
+
+"Well, that's funny," said Tom. "But maybe they say it to themselves.
+Of COURSE they do. Anybody might know that."
+
+The other boys agreed that there was reason in what Tom said, because
+an ignorant lump of bread, uninstructed by an incantation, could not be
+expected to act very intelligently when set upon an errand of such
+gravity.
+
+"By jings, I wish I was over there, now," said Joe.
+
+"I do too" said Huck "I'd give heaps to know who it is."
+
+The boys still listened and watched. Presently a revealing thought
+flashed through Tom's mind, and he exclaimed:
+
+"Boys, I know who's drownded--it's us!"
+
+They felt like heroes in an instant. Here was a gorgeous triumph; they
+were missed; they were mourned; hearts were breaking on their account;
+tears were being shed; accusing memories of unkindness to these poor
+lost lads were rising up, and unavailing regrets and remorse were being
+indulged; and best of all, the departed were the talk of the whole
+town, and the envy of all the boys, as far as this dazzling notoriety
+was concerned. This was fine. It was worth while to be a pirate, after
+all.
+
+As twilight drew on, the ferryboat went back to her accustomed
+business and the skiffs disappeared. The pirates returned to camp. They
+were jubilant with vanity over their new grandeur and the illustrious
+trouble they were making. They caught fish, cooked supper and ate it,
+and then fell to guessing at what the village was thinking and saying
+about them; and the pictures they drew of the public distress on their
+account were gratifying to look upon--from their point of view. But
+when the shadows of night closed them in, they gradually ceased to
+talk, and sat gazing into the fire, with their minds evidently
+wandering elsewhere. The excitement was gone, now, and Tom and Joe
+could not keep back thoughts of certain persons at home who were not
+enjoying this fine frolic as much as they were. Misgivings came; they
+grew troubled and unhappy; a sigh or two escaped, unawares. By and by
+Joe timidly ventured upon a roundabout "feeler" as to how the others
+might look upon a return to civilization--not right now, but--
+
+Tom withered him with derision! Huck, being uncommitted as yet, joined
+in with Tom, and the waverer quickly "explained," and was glad to get
+out of the scrape with as little taint of chicken-hearted homesickness
+clinging to his garments as he could. Mutiny was effectually laid to
+rest for the moment.
+
+As the night deepened, Huck began to nod, and presently to snore. Joe
+followed next. Tom lay upon his elbow motionless, for some time,
+watching the two intently. At last he got up cautiously, on his knees,
+and went searching among the grass and the flickering reflections flung
+by the camp-fire. He picked up and inspected several large
+semi-cylinders of the thin white bark of a sycamore, and finally chose
+two which seemed to suit him. Then he knelt by the fire and painfully
+wrote something upon each of these with his "red keel"; one he rolled up
+and put in his jacket pocket, and the other he put in Joe's hat and
+removed it to a little distance from the owner. And he also put into the
+hat certain schoolboy treasures of almost inestimable value--among them
+a lump of chalk, an India-rubber ball, three fishhooks, and one of that
+kind of marbles known as a "sure 'nough crystal." Then he tiptoed his
+way cautiously among the trees till he felt that he was out of hearing,
+and straightway broke into a keen run in the direction of the sandbar.
+
+
+
+CHAPTER XV
+
+A FEW minutes later Tom was in the shoal water of the bar, wading
+toward the Illinois shore. Before the depth reached his middle he was
+half-way over; the current would permit no more wading, now, so he
+struck out confidently to swim the remaining hundred yards. He swam
+quartering upstream, but still was swept downward rather faster than he
+had expected. However, he reached the shore finally, and drifted along
+till he found a low place and drew himself out. He put his hand on his
+jacket pocket, found his piece of bark safe, and then struck through
+the woods, following the shore, with streaming garments. Shortly before
+ten o'clock he came out into an open place opposite the village, and
+saw the ferryboat lying in the shadow of the trees and the high bank.
+Everything was quiet under the blinking stars. He crept down the bank,
+watching with all his eyes, slipped into the water, swam three or four
+strokes and climbed into the skiff that did "yawl" duty at the boat's
+stern. He laid himself down under the thwarts and waited, panting.
+
+Presently the cracked bell tapped and a voice gave the order to "cast
+off." A minute or two later the skiff's head was standing high up,
+against the boat's swell, and the voyage was begun. Tom felt happy in
+his success, for he knew it was the boat's last trip for the night. At
+the end of a long twelve or fifteen minutes the wheels stopped, and Tom
+slipped overboard and swam ashore in the dusk, landing fifty yards
+downstream, out of danger of possible stragglers.
+
+He flew along unfrequented alleys, and shortly found himself at his
+aunt's back fence. He climbed over, approached the "ell," and looked in
+at the sitting-room window, for a light was burning there. There sat
+Aunt Polly, Sid, Mary, and Joe Harper's mother, grouped together,
+talking. They were by the bed, and the bed was between them and the
+door. Tom went to the door and began to softly lift the latch; then he
+pressed gently and the door yielded a crack; he continued pushing
+cautiously, and quaking every time it creaked, till he judged he might
+squeeze through on his knees; so he put his head through and began,
+warily.
+
+"What makes the candle blow so?" said Aunt Polly. Tom hurried up.
+"Why, that door's open, I believe. Why, of course it is. No end of
+strange things now. Go 'long and shut it, Sid."
+
+Tom disappeared under the bed just in time. He lay and "breathed"
+himself for a time, and then crept to where he could almost touch his
+aunt's foot.
+
+"But as I was saying," said Aunt Polly, "he warn't BAD, so to say
+--only mischEEvous. Only just giddy, and harum-scarum, you know. He
+warn't any more responsible than a colt. HE never meant any harm, and
+he was the best-hearted boy that ever was"--and she began to cry.
+
+"It was just so with my Joe--always full of his devilment, and up to
+every kind of mischief, but he was just as unselfish and kind as he
+could be--and laws bless me, to think I went and whipped him for taking
+that cream, never once recollecting that I throwed it out myself
+because it was sour, and I never to see him again in this world, never,
+never, never, poor abused boy!" And Mrs. Harper sobbed as if her heart
+would break.
+
+"I hope Tom's better off where he is," said Sid, "but if he'd been
+better in some ways--"
+
+"SID!" Tom felt the glare of the old lady's eye, though he could not
+see it. "Not a word against my Tom, now that he's gone! God'll take
+care of HIM--never you trouble YOURself, sir! Oh, Mrs. Harper, I don't
+know how to give him up! I don't know how to give him up! He was such a
+comfort to me, although he tormented my old heart out of me, 'most."
+
+"The Lord giveth and the Lord hath taken away--Blessed be the name of
+the Lord! But it's so hard--Oh, it's so hard! Only last Saturday my
+Joe busted a firecracker right under my nose and I knocked him
+sprawling. Little did I know then, how soon--Oh, if it was to do over
+again I'd hug him and bless him for it."
+
+"Yes, yes, yes, I know just how you feel, Mrs. Harper, I know just
+exactly how you feel. No longer ago than yesterday noon, my Tom took
+and filled the cat full of Pain-killer, and I did think the cretur
+would tear the house down. And God forgive me, I cracked Tom's head
+with my thimble, poor boy, poor dead boy. But he's out of all his
+troubles now. And the last words I ever heard him say was to reproach--"
+
+But this memory was too much for the old lady, and she broke entirely
+down. Tom was snuffling, now, himself--and more in pity of himself than
+anybody else. He could hear Mary crying, and putting in a kindly word
+for him from time to time. He began to have a nobler opinion of himself
+than ever before. Still, he was sufficiently touched by his aunt's
+grief to long to rush out from under the bed and overwhelm her with
+joy--and the theatrical gorgeousness of the thing appealed strongly to
+his nature, too, but he resisted and lay still.
+
+He went on listening, and gathered by odds and ends that it was
+conjectured at first that the boys had got drowned while taking a swim;
+then the small raft had been missed; next, certain boys said the
+missing lads had promised that the village should "hear something"
+soon; the wise-heads had "put this and that together" and decided that
+the lads had gone off on that raft and would turn up at the next town
+below, presently; but toward noon the raft had been found, lodged
+against the Missouri shore some five or six miles below the village
+--and then hope perished; they must be drowned, else hunger would have
+driven them home by nightfall if not sooner. It was believed that the
+search for the bodies had been a fruitless effort merely because the
+drowning must have occurred in mid-channel, since the boys, being good
+swimmers, would otherwise have escaped to shore. This was Wednesday
+night. If the bodies continued missing until Sunday, all hope would be
+given over, and the funerals would be preached on that morning. Tom
+shuddered.
+
+Mrs. Harper gave a sobbing good-night and turned to go. Then with a
+mutual impulse the two bereaved women flung themselves into each
+other's arms and had a good, consoling cry, and then parted. Aunt Polly
+was tender far beyond her wont, in her good-night to Sid and Mary. Sid
+snuffled a bit and Mary went off crying with all her heart.
+
+Aunt Polly knelt down and prayed for Tom so touchingly, so
+appealingly, and with such measureless love in her words and her old
+trembling voice, that he was weltering in tears again, long before she
+was through.
+
+He had to keep still long after she went to bed, for she kept making
+broken-hearted ejaculations from time to time, tossing unrestfully, and
+turning over. But at last she was still, only moaning a little in her
+sleep. Now the boy stole out, rose gradually by the bedside, shaded the
+candle-light with his hand, and stood regarding her. His heart was full
+of pity for her. He took out his sycamore scroll and placed it by the
+candle. But something occurred to him, and he lingered considering. His
+face lighted with a happy solution of his thought; he put the bark
+hastily in his pocket. Then he bent over and kissed the faded lips, and
+straightway made his stealthy exit, latching the door behind him.
+
+He threaded his way back to the ferry landing, found nobody at large
+there, and walked boldly on board the boat, for he knew she was
+tenantless except that there was a watchman, who always turned in and
+slept like a graven image. He untied the skiff at the stern, slipped
+into it, and was soon rowing cautiously upstream. When he had pulled a
+mile above the village, he started quartering across and bent himself
+stoutly to his work. He hit the landing on the other side neatly, for
+this was a familiar bit of work to him. He was moved to capture the
+skiff, arguing that it might be considered a ship and therefore
+legitimate prey for a pirate, but he knew a thorough search would be
+made for it and that might end in revelations. So he stepped ashore and
+entered the woods.
+
+He sat down and took a long rest, torturing himself meanwhile to keep
+awake, and then started warily down the home-stretch. The night was far
+spent. It was broad daylight before he found himself fairly abreast the
+island bar. He rested again until the sun was well up and gilding the
+great river with its splendor, and then he plunged into the stream. A
+little later he paused, dripping, upon the threshold of the camp, and
+heard Joe say:
+
+"No, Tom's true-blue, Huck, and he'll come back. He won't desert. He
+knows that would be a disgrace to a pirate, and Tom's too proud for
+that sort of thing. He's up to something or other. Now I wonder what?"
+
+"Well, the things is ours, anyway, ain't they?"
+
+"Pretty near, but not yet, Huck. The writing says they are if he ain't
+back here to breakfast."
+
+"Which he is!" exclaimed Tom, with fine dramatic effect, stepping
+grandly into camp.
+
+A sumptuous breakfast of bacon and fish was shortly provided, and as
+the boys set to work upon it, Tom recounted (and adorned) his
+adventures. They were a vain and boastful company of heroes when the
+tale was done. Then Tom hid himself away in a shady nook to sleep till
+noon, and the other pirates got ready to fish and explore.
+
+
+
+CHAPTER XVI
+
+AFTER dinner all the gang turned out to hunt for turtle eggs on the
+bar. They went about poking sticks into the sand, and when they found a
+soft place they went down on their knees and dug with their hands.
+Sometimes they would take fifty or sixty eggs out of one hole. They
+were perfectly round white things a trifle smaller than an English
+walnut. They had a famous fried-egg feast that night, and another on
+Friday morning.
+
+After breakfast they went whooping and prancing out on the bar, and
+chased each other round and round, shedding clothes as they went, until
+they were naked, and then continued the frolic far away up the shoal
+water of the bar, against the stiff current, which latter tripped their
+legs from under them from time to time and greatly increased the fun.
+And now and then they stooped in a group and splashed water in each
+other's faces with their palms, gradually approaching each other, with
+averted faces to avoid the strangling sprays, and finally gripping and
+struggling till the best man ducked his neighbor, and then they all
+went under in a tangle of white legs and arms and came up blowing,
+sputtering, laughing, and gasping for breath at one and the same time.
+
+When they were well exhausted, they would run out and sprawl on the
+dry, hot sand, and lie there and cover themselves up with it, and by
+and by break for the water again and go through the original
+performance once more. Finally it occurred to them that their naked
+skin represented flesh-colored "tights" very fairly; so they drew a
+ring in the sand and had a circus--with three clowns in it, for none
+would yield this proudest post to his neighbor.
+
+Next they got their marbles and played "knucks" and "ring-taw" and
+"keeps" till that amusement grew stale. Then Joe and Huck had another
+swim, but Tom would not venture, because he found that in kicking off
+his trousers he had kicked his string of rattlesnake rattles off his
+ankle, and he wondered how he had escaped cramp so long without the
+protection of this mysterious charm. He did not venture again until he
+had found it, and by that time the other boys were tired and ready to
+rest. They gradually wandered apart, dropped into the "dumps," and fell
+to gazing longingly across the wide river to where the village lay
+drowsing in the sun. Tom found himself writing "BECKY" in the sand with
+his big toe; he scratched it out, and was angry with himself for his
+weakness. But he wrote it again, nevertheless; he could not help it. He
+erased it once more and then took himself out of temptation by driving
+the other boys together and joining them.
+
+But Joe's spirits had gone down almost beyond resurrection. He was so
+homesick that he could hardly endure the misery of it. The tears lay
+very near the surface. Huck was melancholy, too. Tom was downhearted,
+but tried hard not to show it. He had a secret which he was not ready
+to tell, yet, but if this mutinous depression was not broken up soon,
+he would have to bring it out. He said, with a great show of
+cheerfulness:
+
+"I bet there's been pirates on this island before, boys. We'll explore
+it again. They've hid treasures here somewhere. How'd you feel to light
+on a rotten chest full of gold and silver--hey?"
+
+But it roused only faint enthusiasm, which faded out, with no reply.
+Tom tried one or two other seductions; but they failed, too. It was
+discouraging work. Joe sat poking up the sand with a stick and looking
+very gloomy. Finally he said:
+
+"Oh, boys, let's give it up. I want to go home. It's so lonesome."
+
+"Oh no, Joe, you'll feel better by and by," said Tom. "Just think of
+the fishing that's here."
+
+"I don't care for fishing. I want to go home."
+
+"But, Joe, there ain't such another swimming-place anywhere."
+
+"Swimming's no good. I don't seem to care for it, somehow, when there
+ain't anybody to say I sha'n't go in. I mean to go home."
+
+"Oh, shucks! Baby! You want to see your mother, I reckon."
+
+"Yes, I DO want to see my mother--and you would, too, if you had one.
+I ain't any more baby than you are." And Joe snuffled a little.
+
+"Well, we'll let the cry-baby go home to his mother, won't we, Huck?
+Poor thing--does it want to see its mother? And so it shall. You like
+it here, don't you, Huck? We'll stay, won't we?"
+
+Huck said, "Y-e-s"--without any heart in it.
+
+"I'll never speak to you again as long as I live," said Joe, rising.
+"There now!" And he moved moodily away and began to dress himself.
+
+"Who cares!" said Tom. "Nobody wants you to. Go 'long home and get
+laughed at. Oh, you're a nice pirate. Huck and me ain't cry-babies.
+We'll stay, won't we, Huck? Let him go if he wants to. I reckon we can
+get along without him, per'aps."
+
+But Tom was uneasy, nevertheless, and was alarmed to see Joe go
+sullenly on with his dressing. And then it was discomforting to see
+Huck eying Joe's preparations so wistfully, and keeping up such an
+ominous silence. Presently, without a parting word, Joe began to wade
+off toward the Illinois shore. Tom's heart began to sink. He glanced at
+Huck. Huck could not bear the look, and dropped his eyes. Then he said:
+
+"I want to go, too, Tom. It was getting so lonesome anyway, and now
+it'll be worse. Let's us go, too, Tom."
+
+"I won't! You can all go, if you want to. I mean to stay."
+
+"Tom, I better go."
+
+"Well, go 'long--who's hendering you."
+
+Huck began to pick up his scattered clothes. He said:
+
+"Tom, I wisht you'd come, too. Now you think it over. We'll wait for
+you when we get to shore."
+
+"Well, you'll wait a blame long time, that's all."
+
+Huck started sorrowfully away, and Tom stood looking after him, with a
+strong desire tugging at his heart to yield his pride and go along too.
+He hoped the boys would stop, but they still waded slowly on. It
+suddenly dawned on Tom that it was become very lonely and still. He
+made one final struggle with his pride, and then darted after his
+comrades, yelling:
+
+"Wait! Wait! I want to tell you something!"
+
+They presently stopped and turned around. When he got to where they
+were, he began unfolding his secret, and they listened moodily till at
+last they saw the "point" he was driving at, and then they set up a
+war-whoop of applause and said it was "splendid!" and said if he had
+told them at first, they wouldn't have started away. He made a plausible
+excuse; but his real reason had been the fear that not even the secret
+would keep them with him any very great length of time, and so he had
+meant to hold it in reserve as a last seduction.
+
+The lads came gayly back and went at their sports again with a will,
+chattering all the time about Tom's stupendous plan and admiring the
+genius of it. After a dainty egg and fish dinner, Tom said he wanted to
+learn to smoke, now. Joe caught at the idea and said he would like to
+try, too. So Huck made pipes and filled them. These novices had never
+smoked anything before but cigars made of grape-vine, and they "bit"
+the tongue, and were not considered manly anyway.
+
+Now they stretched themselves out on their elbows and began to puff,
+charily, and with slender confidence. The smoke had an unpleasant
+taste, and they gagged a little, but Tom said:
+
+"Why, it's just as easy! If I'd a knowed this was all, I'd a learnt
+long ago."
+
+"So would I," said Joe. "It's just nothing."
+
+"Why, many a time I've looked at people smoking, and thought well I
+wish I could do that; but I never thought I could," said Tom.
+
+"That's just the way with me, hain't it, Huck? You've heard me talk
+just that way--haven't you, Huck? I'll leave it to Huck if I haven't."
+
+"Yes--heaps of times," said Huck.
+
+"Well, I have too," said Tom; "oh, hundreds of times. Once down by the
+slaughter-house. Don't you remember, Huck? Bob Tanner was there, and
+Johnny Miller, and Jeff Thatcher, when I said it. Don't you remember,
+Huck, 'bout me saying that?"
+
+"Yes, that's so," said Huck. "That was the day after I lost a white
+alley. No, 'twas the day before."
+
+"There--I told you so," said Tom. "Huck recollects it."
+
+"I bleeve I could smoke this pipe all day," said Joe. "I don't feel
+sick."
+
+"Neither do I," said Tom. "I could smoke it all day. But I bet you
+Jeff Thatcher couldn't."
+
+"Jeff Thatcher! Why, he'd keel over just with two draws. Just let him
+try it once. HE'D see!"
+
+"I bet he would. And Johnny Miller--I wish could see Johnny Miller
+tackle it once."
+
+"Oh, don't I!" said Joe. "Why, I bet you Johnny Miller couldn't any
+more do this than nothing. Just one little snifter would fetch HIM."
+
+"'Deed it would, Joe. Say--I wish the boys could see us now."
+
+"So do I."
+
+"Say--boys, don't say anything about it, and some time when they're
+around, I'll come up to you and say, 'Joe, got a pipe? I want a smoke.'
+And you'll say, kind of careless like, as if it warn't anything, you'll
+say, 'Yes, I got my OLD pipe, and another one, but my tobacker ain't
+very good.' And I'll say, 'Oh, that's all right, if it's STRONG
+enough.' And then you'll out with the pipes, and we'll light up just as
+ca'm, and then just see 'em look!"
+
+"By jings, that'll be gay, Tom! I wish it was NOW!"
+
+"So do I! And when we tell 'em we learned when we was off pirating,
+won't they wish they'd been along?"
+
+"Oh, I reckon not! I'll just BET they will!"
+
+So the talk ran on. But presently it began to flag a trifle, and grow
+disjointed. The silences widened; the expectoration marvellously
+increased. Every pore inside the boys' cheeks became a spouting
+fountain; they could scarcely bail out the cellars under their tongues
+fast enough to prevent an inundation; little overflowings down their
+throats occurred in spite of all they could do, and sudden retchings
+followed every time. Both boys were looking very pale and miserable,
+now. Joe's pipe dropped from his nerveless fingers. Tom's followed.
+Both fountains were going furiously and both pumps bailing with might
+and main. Joe said feebly:
+
+"I've lost my knife. I reckon I better go and find it."
+
+Tom said, with quivering lips and halting utterance:
+
+"I'll help you. You go over that way and I'll hunt around by the
+spring. No, you needn't come, Huck--we can find it."
+
+So Huck sat down again, and waited an hour. Then he found it lonesome,
+and went to find his comrades. They were wide apart in the woods, both
+very pale, both fast asleep. But something informed him that if they
+had had any trouble they had got rid of it.
+
+They were not talkative at supper that night. They had a humble look,
+and when Huck prepared his pipe after the meal and was going to prepare
+theirs, they said no, they were not feeling very well--something they
+ate at dinner had disagreed with them.
+
+About midnight Joe awoke, and called the boys. There was a brooding
+oppressiveness in the air that seemed to bode something. The boys
+huddled themselves together and sought the friendly companionship of
+the fire, though the dull dead heat of the breathless atmosphere was
+stifling. They sat still, intent and waiting. The solemn hush
+continued. Beyond the light of the fire everything was swallowed up in
+the blackness of darkness. Presently there came a quivering glow that
+vaguely revealed the foliage for a moment and then vanished. By and by
+another came, a little stronger. Then another. Then a faint moan came
+sighing through the branches of the forest and the boys felt a fleeting
+breath upon their cheeks, and shuddered with the fancy that the Spirit
+of the Night had gone by. There was a pause. Now a weird flash turned
+night into day and showed every little grass-blade, separate and
+distinct, that grew about their feet. And it showed three white,
+startled faces, too. A deep peal of thunder went rolling and tumbling
+down the heavens and lost itself in sullen rumblings in the distance. A
+sweep of chilly air passed by, rustling all the leaves and snowing the
+flaky ashes broadcast about the fire. Another fierce glare lit up the
+forest and an instant crash followed that seemed to rend the tree-tops
+right over the boys' heads. They clung together in terror, in the thick
+gloom that followed. A few big rain-drops fell pattering upon the
+leaves.
+
+"Quick! boys, go for the tent!" exclaimed Tom.
+
+They sprang away, stumbling over roots and among vines in the dark, no
+two plunging in the same direction. A furious blast roared through the
+trees, making everything sing as it went. One blinding flash after
+another came, and peal on peal of deafening thunder. And now a
+drenching rain poured down and the rising hurricane drove it in sheets
+along the ground. The boys cried out to each other, but the roaring
+wind and the booming thunder-blasts drowned their voices utterly.
+However, one by one they straggled in at last and took shelter under
+the tent, cold, scared, and streaming with water; but to have company
+in misery seemed something to be grateful for. They could not talk, the
+old sail flapped so furiously, even if the other noises would have
+allowed them. The tempest rose higher and higher, and presently the
+sail tore loose from its fastenings and went winging away on the blast.
+The boys seized each others' hands and fled, with many tumblings and
+bruises, to the shelter of a great oak that stood upon the river-bank.
+Now the battle was at its highest. Under the ceaseless conflagration of
+lightning that flamed in the skies, everything below stood out in
+clean-cut and shadowless distinctness: the bending trees, the billowy
+river, white with foam, the driving spray of spume-flakes, the dim
+outlines of the high bluffs on the other side, glimpsed through the
+drifting cloud-rack and the slanting veil of rain. Every little while
+some giant tree yielded the fight and fell crashing through the younger
+growth; and the unflagging thunder-peals came now in ear-splitting
+explosive bursts, keen and sharp, and unspeakably appalling. The storm
+culminated in one matchless effort that seemed likely to tear the island
+to pieces, burn it up, drown it to the tree-tops, blow it away, and
+deafen every creature in it, all at one and the same moment. It was a
+wild night for homeless young heads to be out in.
+
+But at last the battle was done, and the forces retired with weaker
+and weaker threatenings and grumblings, and peace resumed her sway. The
+boys went back to camp, a good deal awed; but they found there was
+still something to be thankful for, because the great sycamore, the
+shelter of their beds, was a ruin, now, blasted by the lightnings, and
+they were not under it when the catastrophe happened.
+
+Everything in camp was drenched, the camp-fire as well; for they were
+but heedless lads, like their generation, and had made no provision
+against rain. Here was matter for dismay, for they were soaked through
+and chilled. They were eloquent in their distress; but they presently
+discovered that the fire had eaten so far up under the great log it had
+been built against (where it curved upward and separated itself from
+the ground), that a handbreadth or so of it had escaped wetting; so
+they patiently wrought until, with shreds and bark gathered from the
+under sides of sheltered logs, they coaxed the fire to burn again. Then
+they piled on great dead boughs till they had a roaring furnace, and
+were glad-hearted once more. They dried their boiled ham and had a
+feast, and after that they sat by the fire and expanded and glorified
+their midnight adventure until morning, for there was not a dry spot to
+sleep on, anywhere around.
+
+As the sun began to steal in upon the boys, drowsiness came over them,
+and they went out on the sandbar and lay down to sleep. They got
+scorched out by and by, and drearily set about getting breakfast. After
+the meal they felt rusty, and stiff-jointed, and a little homesick once
+more. Tom saw the signs, and fell to cheering up the pirates as well as
+he could. But they cared nothing for marbles, or circus, or swimming,
+or anything. He reminded them of the imposing secret, and raised a ray
+of cheer. While it lasted, he got them interested in a new device. This
+was to knock off being pirates, for a while, and be Indians for a
+change. They were attracted by this idea; so it was not long before
+they were stripped, and striped from head to heel with black mud, like
+so many zebras--all of them chiefs, of course--and then they went
+tearing through the woods to attack an English settlement.
+
+By and by they separated into three hostile tribes, and darted upon
+each other from ambush with dreadful war-whoops, and killed and scalped
+each other by thousands. It was a gory day. Consequently it was an
+extremely satisfactory one.
+
+They assembled in camp toward supper-time, hungry and happy; but now a
+difficulty arose--hostile Indians could not break the bread of
+hospitality together without first making peace, and this was a simple
+impossibility without smoking a pipe of peace. There was no other
+process that ever they had heard of. Two of the savages almost wished
+they had remained pirates. However, there was no other way; so with
+such show of cheerfulness as they could muster they called for the pipe
+and took their whiff as it passed, in due form.
+
+And behold, they were glad they had gone into savagery, for they had
+gained something; they found that they could now smoke a little without
+having to go and hunt for a lost knife; they did not get sick enough to
+be seriously uncomfortable. They were not likely to fool away this high
+promise for lack of effort. No, they practised cautiously, after
+supper, with right fair success, and so they spent a jubilant evening.
+They were prouder and happier in their new acquirement than they would
+have been in the scalping and skinning of the Six Nations. We will
+leave them to smoke and chatter and brag, since we have no further use
+for them at present.
+
+
+
+CHAPTER XVII
+
+BUT there was no hilarity in the little town that same tranquil
+Saturday afternoon. The Harpers, and Aunt Polly's family, were being
+put into mourning, with great grief and many tears. An unusual quiet
+possessed the village, although it was ordinarily quiet enough, in all
+conscience. The villagers conducted their concerns with an absent air,
+and talked little; but they sighed often. The Saturday holiday seemed a
+burden to the children. They had no heart in their sports, and
+gradually gave them up.
+
+In the afternoon Becky Thatcher found herself moping about the
+deserted schoolhouse yard, and feeling very melancholy. But she found
+nothing there to comfort her. She soliloquized:
+
+"Oh, if I only had a brass andiron-knob again! But I haven't got
+anything now to remember him by." And she choked back a little sob.
+
+Presently she stopped, and said to herself:
+
+"It was right here. Oh, if it was to do over again, I wouldn't say
+that--I wouldn't say it for the whole world. But he's gone now; I'll
+never, never, never see him any more."
+
+This thought broke her down, and she wandered away, with tears rolling
+down her cheeks. Then quite a group of boys and girls--playmates of
+Tom's and Joe's--came by, and stood looking over the paling fence and
+talking in reverent tones of how Tom did so-and-so the last time they
+saw him, and how Joe said this and that small trifle (pregnant with
+awful prophecy, as they could easily see now!)--and each speaker
+pointed out the exact spot where the lost lads stood at the time, and
+then added something like "and I was a-standing just so--just as I am
+now, and as if you was him--I was as close as that--and he smiled, just
+this way--and then something seemed to go all over me, like--awful, you
+know--and I never thought what it meant, of course, but I can see now!"
+
+Then there was a dispute about who saw the dead boys last in life, and
+many claimed that dismal distinction, and offered evidences, more or
+less tampered with by the witness; and when it was ultimately decided
+who DID see the departed last, and exchanged the last words with them,
+the lucky parties took upon themselves a sort of sacred importance, and
+were gaped at and envied by all the rest. One poor chap, who had no
+other grandeur to offer, said with tolerably manifest pride in the
+remembrance:
+
+"Well, Tom Sawyer he licked me once."
+
+But that bid for glory was a failure. Most of the boys could say that,
+and so that cheapened the distinction too much. The group loitered
+away, still recalling memories of the lost heroes, in awed voices.
+
+When the Sunday-school hour was finished, the next morning, the bell
+began to toll, instead of ringing in the usual way. It was a very still
+Sabbath, and the mournful sound seemed in keeping with the musing hush
+that lay upon nature. The villagers began to gather, loitering a moment
+in the vestibule to converse in whispers about the sad event. But there
+was no whispering in the house; only the funereal rustling of dresses
+as the women gathered to their seats disturbed the silence there. None
+could remember when the little church had been so full before. There
+was finally a waiting pause, an expectant dumbness, and then Aunt Polly
+entered, followed by Sid and Mary, and they by the Harper family, all
+in deep black, and the whole congregation, the old minister as well,
+rose reverently and stood until the mourners were seated in the front
+pew. There was another communing silence, broken at intervals by
+muffled sobs, and then the minister spread his hands abroad and prayed.
+A moving hymn was sung, and the text followed: "I am the Resurrection
+and the Life."
+
+As the service proceeded, the clergyman drew such pictures of the
+graces, the winning ways, and the rare promise of the lost lads that
+every soul there, thinking he recognized these pictures, felt a pang in
+remembering that he had persistently blinded himself to them always
+before, and had as persistently seen only faults and flaws in the poor
+boys. The minister related many a touching incident in the lives of the
+departed, too, which illustrated their sweet, generous natures, and the
+people could easily see, now, how noble and beautiful those episodes
+were, and remembered with grief that at the time they occurred they had
+seemed rank rascalities, well deserving of the cowhide. The
+congregation became more and more moved, as the pathetic tale went on,
+till at last the whole company broke down and joined the weeping
+mourners in a chorus of anguished sobs, the preacher himself giving way
+to his feelings, and crying in the pulpit.
+
+There was a rustle in the gallery, which nobody noticed; a moment
+later the church door creaked; the minister raised his streaming eyes
+above his handkerchief, and stood transfixed! First one and then
+another pair of eyes followed the minister's, and then almost with one
+impulse the congregation rose and stared while the three dead boys came
+marching up the aisle, Tom in the lead, Joe next, and Huck, a ruin of
+drooping rags, sneaking sheepishly in the rear! They had been hid in
+the unused gallery listening to their own funeral sermon!
+
+Aunt Polly, Mary, and the Harpers threw themselves upon their restored
+ones, smothered them with kisses and poured out thanksgivings, while
+poor Huck stood abashed and uncomfortable, not knowing exactly what to
+do or where to hide from so many unwelcoming eyes. He wavered, and
+started to slink away, but Tom seized him and said:
+
+"Aunt Polly, it ain't fair. Somebody's got to be glad to see Huck."
+
+"And so they shall. I'm glad to see him, poor motherless thing!" And
+the loving attentions Aunt Polly lavished upon him were the one thing
+capable of making him more uncomfortable than he was before.
+
+Suddenly the minister shouted at the top of his voice: "Praise God
+from whom all blessings flow--SING!--and put your hearts in it!"
+
+And they did. Old Hundred swelled up with a triumphant burst, and
+while it shook the rafters Tom Sawyer the Pirate looked around upon the
+envying juveniles about him and confessed in his heart that this was
+the proudest moment of his life.
+
+As the "sold" congregation trooped out they said they would almost be
+willing to be made ridiculous again to hear Old Hundred sung like that
+once more.
+
+Tom got more cuffs and kisses that day--according to Aunt Polly's
+varying moods--than he had earned before in a year; and he hardly knew
+which expressed the most gratefulness to God and affection for himself.
+
+
+
+CHAPTER XVIII
+
+THAT was Tom's great secret--the scheme to return home with his
+brother pirates and attend their own funerals. They had paddled over to
+the Missouri shore on a log, at dusk on Saturday, landing five or six
+miles below the village; they had slept in the woods at the edge of the
+town till nearly daylight, and had then crept through back lanes and
+alleys and finished their sleep in the gallery of the church among a
+chaos of invalided benches.
+
+At breakfast, Monday morning, Aunt Polly and Mary were very loving to
+Tom, and very attentive to his wants. There was an unusual amount of
+talk. In the course of it Aunt Polly said:
+
+"Well, I don't say it wasn't a fine joke, Tom, to keep everybody
+suffering 'most a week so you boys had a good time, but it is a pity
+you could be so hard-hearted as to let me suffer so. If you could come
+over on a log to go to your funeral, you could have come over and give
+me a hint some way that you warn't dead, but only run off."
+
+"Yes, you could have done that, Tom," said Mary; "and I believe you
+would if you had thought of it."
+
+"Would you, Tom?" said Aunt Polly, her face lighting wistfully. "Say,
+now, would you, if you'd thought of it?"
+
+"I--well, I don't know. 'Twould 'a' spoiled everything."
+
+"Tom, I hoped you loved me that much," said Aunt Polly, with a grieved
+tone that discomforted the boy. "It would have been something if you'd
+cared enough to THINK of it, even if you didn't DO it."
+
+"Now, auntie, that ain't any harm," pleaded Mary; "it's only Tom's
+giddy way--he is always in such a rush that he never thinks of
+anything."
+
+"More's the pity. Sid would have thought. And Sid would have come and
+DONE it, too. Tom, you'll look back, some day, when it's too late, and
+wish you'd cared a little more for me when it would have cost you so
+little."
+
+"Now, auntie, you know I do care for you," said Tom.
+
+"I'd know it better if you acted more like it."
+
+"I wish now I'd thought," said Tom, with a repentant tone; "but I
+dreamt about you, anyway. That's something, ain't it?"
+
+"It ain't much--a cat does that much--but it's better than nothing.
+What did you dream?"
+
+"Why, Wednesday night I dreamt that you was sitting over there by the
+bed, and Sid was sitting by the woodbox, and Mary next to him."
+
+"Well, so we did. So we always do. I'm glad your dreams could take
+even that much trouble about us."
+
+"And I dreamt that Joe Harper's mother was here."
+
+"Why, she was here! Did you dream any more?"
+
+"Oh, lots. But it's so dim, now."
+
+"Well, try to recollect--can't you?"
+
+"Somehow it seems to me that the wind--the wind blowed the--the--"
+
+"Try harder, Tom! The wind did blow something. Come!"
+
+Tom pressed his fingers on his forehead an anxious minute, and then
+said:
+
+"I've got it now! I've got it now! It blowed the candle!"
+
+"Mercy on us! Go on, Tom--go on!"
+
+"And it seems to me that you said, 'Why, I believe that that door--'"
+
+"Go ON, Tom!"
+
+"Just let me study a moment--just a moment. Oh, yes--you said you
+believed the door was open."
+
+"As I'm sitting here, I did! Didn't I, Mary! Go on!"
+
+"And then--and then--well I won't be certain, but it seems like as if
+you made Sid go and--and--"
+
+"Well? Well? What did I make him do, Tom? What did I make him do?"
+
+"You made him--you--Oh, you made him shut it."
+
+"Well, for the land's sake! I never heard the beat of that in all my
+days! Don't tell ME there ain't anything in dreams, any more. Sereny
+Harper shall know of this before I'm an hour older. I'd like to see her
+get around THIS with her rubbage 'bout superstition. Go on, Tom!"
+
+"Oh, it's all getting just as bright as day, now. Next you said I
+warn't BAD, only mischeevous and harum-scarum, and not any more
+responsible than--than--I think it was a colt, or something."
+
+"And so it was! Well, goodness gracious! Go on, Tom!"
+
+"And then you began to cry."
+
+"So I did. So I did. Not the first time, neither. And then--"
+
+"Then Mrs. Harper she began to cry, and said Joe was just the same,
+and she wished she hadn't whipped him for taking cream when she'd
+throwed it out her own self--"
+
+"Tom! The sperrit was upon you! You was a prophesying--that's what you
+was doing! Land alive, go on, Tom!"
+
+"Then Sid he said--he said--"
+
+"I don't think I said anything," said Sid.
+
+"Yes you did, Sid," said Mary.
+
+"Shut your heads and let Tom go on! What did he say, Tom?"
+
+"He said--I THINK he said he hoped I was better off where I was gone
+to, but if I'd been better sometimes--"
+
+"THERE, d'you hear that! It was his very words!"
+
+"And you shut him up sharp."
+
+"I lay I did! There must 'a' been an angel there. There WAS an angel
+there, somewheres!"
+
+"And Mrs. Harper told about Joe scaring her with a firecracker, and
+you told about Peter and the Painkiller--"
+
+"Just as true as I live!"
+
+"And then there was a whole lot of talk 'bout dragging the river for
+us, and 'bout having the funeral Sunday, and then you and old Miss
+Harper hugged and cried, and she went."
+
+"It happened just so! It happened just so, as sure as I'm a-sitting in
+these very tracks. Tom, you couldn't told it more like if you'd 'a'
+seen it! And then what? Go on, Tom!"
+
+"Then I thought you prayed for me--and I could see you and hear every
+word you said. And you went to bed, and I was so sorry that I took and
+wrote on a piece of sycamore bark, 'We ain't dead--we are only off
+being pirates,' and put it on the table by the candle; and then you
+looked so good, laying there asleep, that I thought I went and leaned
+over and kissed you on the lips."
+
+"Did you, Tom, DID you! I just forgive you everything for that!" And
+she seized the boy in a crushing embrace that made him feel like the
+guiltiest of villains.
+
+"It was very kind, even though it was only a--dream," Sid soliloquized
+just audibly.
+
+"Shut up, Sid! A body does just the same in a dream as he'd do if he
+was awake. Here's a big Milum apple I've been saving for you, Tom, if
+you was ever found again--now go 'long to school. I'm thankful to the
+good God and Father of us all I've got you back, that's long-suffering
+and merciful to them that believe on Him and keep His word, though
+goodness knows I'm unworthy of it, but if only the worthy ones got His
+blessings and had His hand to help them over the rough places, there's
+few enough would smile here or ever enter into His rest when the long
+night comes. Go 'long Sid, Mary, Tom--take yourselves off--you've
+hendered me long enough."
+
+The children left for school, and the old lady to call on Mrs. Harper
+and vanquish her realism with Tom's marvellous dream. Sid had better
+judgment than to utter the thought that was in his mind as he left the
+house. It was this: "Pretty thin--as long a dream as that, without any
+mistakes in it!"
+
+What a hero Tom was become, now! He did not go skipping and prancing,
+but moved with a dignified swagger as became a pirate who felt that the
+public eye was on him. And indeed it was; he tried not to seem to see
+the looks or hear the remarks as he passed along, but they were food
+and drink to him. Smaller boys than himself flocked at his heels, as
+proud to be seen with him, and tolerated by him, as if he had been the
+drummer at the head of a procession or the elephant leading a menagerie
+into town. Boys of his own size pretended not to know he had been away
+at all; but they were consuming with envy, nevertheless. They would
+have given anything to have that swarthy suntanned skin of his, and his
+glittering notoriety; and Tom would not have parted with either for a
+circus.
+
+At school the children made so much of him and of Joe, and delivered
+such eloquent admiration from their eyes, that the two heroes were not
+long in becoming insufferably "stuck-up." They began to tell their
+adventures to hungry listeners--but they only began; it was not a thing
+likely to have an end, with imaginations like theirs to furnish
+material. And finally, when they got out their pipes and went serenely
+puffing around, the very summit of glory was reached.
+
+Tom decided that he could be independent of Becky Thatcher now. Glory
+was sufficient. He would live for glory. Now that he was distinguished,
+maybe she would be wanting to "make up." Well, let her--she should see
+that he could be as indifferent as some other people. Presently she
+arrived. Tom pretended not to see her. He moved away and joined a group
+of boys and girls and began to talk. Soon he observed that she was
+tripping gayly back and forth with flushed face and dancing eyes,
+pretending to be busy chasing schoolmates, and screaming with laughter
+when she made a capture; but he noticed that she always made her
+captures in his vicinity, and that she seemed to cast a conscious eye
+in his direction at such times, too. It gratified all the vicious
+vanity that was in him; and so, instead of winning him, it only "set
+him up" the more and made him the more diligent to avoid betraying that
+he knew she was about. Presently she gave over skylarking, and moved
+irresolutely about, sighing once or twice and glancing furtively and
+wistfully toward Tom. Then she observed that now Tom was talking more
+particularly to Amy Lawrence than to any one else. She felt a sharp
+pang and grew disturbed and uneasy at once. She tried to go away, but
+her feet were treacherous, and carried her to the group instead. She
+said to a girl almost at Tom's elbow--with sham vivacity:
+
+"Why, Mary Austin! you bad girl, why didn't you come to Sunday-school?"
+
+"I did come--didn't you see me?"
+
+"Why, no! Did you? Where did you sit?"
+
+"I was in Miss Peters' class, where I always go. I saw YOU."
+
+"Did you? Why, it's funny I didn't see you. I wanted to tell you about
+the picnic."
+
+"Oh, that's jolly. Who's going to give it?"
+
+"My ma's going to let me have one."
+
+"Oh, goody; I hope she'll let ME come."
+
+"Well, she will. The picnic's for me. She'll let anybody come that I
+want, and I want you."
+
+"That's ever so nice. When is it going to be?"
+
+"By and by. Maybe about vacation."
+
+"Oh, won't it be fun! You going to have all the girls and boys?"
+
+"Yes, every one that's friends to me--or wants to be"; and she glanced
+ever so furtively at Tom, but he talked right along to Amy Lawrence
+about the terrible storm on the island, and how the lightning tore the
+great sycamore tree "all to flinders" while he was "standing within
+three feet of it."
+
+"Oh, may I come?" said Grace Miller.
+
+"Yes."
+
+"And me?" said Sally Rogers.
+
+"Yes."
+
+"And me, too?" said Susy Harper. "And Joe?"
+
+"Yes."
+
+And so on, with clapping of joyful hands till all the group had begged
+for invitations but Tom and Amy. Then Tom turned coolly away, still
+talking, and took Amy with him. Becky's lips trembled and the tears
+came to her eyes; she hid these signs with a forced gayety and went on
+chattering, but the life had gone out of the picnic, now, and out of
+everything else; she got away as soon as she could and hid herself and
+had what her sex call "a good cry." Then she sat moody, with wounded
+pride, till the bell rang. She roused up, now, with a vindictive cast
+in her eye, and gave her plaited tails a shake and said she knew what
+SHE'D do.
+
+At recess Tom continued his flirtation with Amy with jubilant
+self-satisfaction. And he kept drifting about to find Becky and lacerate
+her with the performance. At last he spied her, but there was a sudden
+falling of his mercury. She was sitting cosily on a little bench behind
+the schoolhouse looking at a picture-book with Alfred Temple--and so
+absorbed were they, and their heads so close together over the book,
+that they did not seem to be conscious of anything in the world besides.
+Jealousy ran red-hot through Tom's veins. He began to hate himself for
+throwing away the chance Becky had offered for a reconciliation. He
+called himself a fool, and all the hard names he could think of. He
+wanted to cry with vexation. Amy chatted happily along, as they walked,
+for her heart was singing, but Tom's tongue had lost its function. He
+did not hear what Amy was saying, and whenever she paused expectantly he
+could only stammer an awkward assent, which was as often misplaced as
+otherwise. He kept drifting to the rear of the schoolhouse, again and
+again, to sear his eyeballs with the hateful spectacle there. He could
+not help it. And it maddened him to see, as he thought he saw, that
+Becky Thatcher never once suspected that he was even in the land of the
+living. But she did see, nevertheless; and she knew she was winning her
+fight, too, and was glad to see him suffer as she had suffered.
+
+Amy's happy prattle became intolerable. Tom hinted at things he had to
+attend to; things that must be done; and time was fleeting. But in
+vain--the girl chirped on. Tom thought, "Oh, hang her, ain't I ever
+going to get rid of her?" At last he must be attending to those
+things--and she said artlessly that she would be "around" when school
+let out. And he hastened away, hating her for it.
+
+"Any other boy!" Tom thought, grating his teeth. "Any boy in the whole
+town but that Saint Louis smarty that thinks he dresses so fine and is
+aristocracy! Oh, all right, I licked you the first day you ever saw
+this town, mister, and I'll lick you again! You just wait till I catch
+you out! I'll just take and--"
+
+And he went through the motions of thrashing an imaginary boy
+--pummelling the air, and kicking and gouging. "Oh, you do, do you? You
+holler 'nough, do you? Now, then, let that learn you!" And so the
+imaginary flogging was finished to his satisfaction.
+
+Tom fled home at noon. His conscience could not endure any more of
+Amy's grateful happiness, and his jealousy could bear no more of the
+other distress. Becky resumed her picture inspections with Alfred, but
+as the minutes dragged along and no Tom came to suffer, her triumph
+began to cloud and she lost interest; gravity and absent-mindedness
+followed, and then melancholy; two or three times she pricked up her
+ear at a footstep, but it was a false hope; no Tom came. At last she
+grew entirely miserable and wished she hadn't carried it so far. When
+poor Alfred, seeing that he was losing her, he did not know how, kept
+exclaiming: "Oh, here's a jolly one! look at this!" she lost patience
+at last, and said, "Oh, don't bother me! I don't care for them!" and
+burst into tears, and got up and walked away.
+
+Alfred dropped alongside and was going to try to comfort her, but she
+said:
+
+"Go away and leave me alone, can't you! I hate you!"
+
+So the boy halted, wondering what he could have done--for she had said
+she would look at pictures all through the nooning--and she walked on,
+crying. Then Alfred went musing into the deserted schoolhouse. He was
+humiliated and angry. He easily guessed his way to the truth--the girl
+had simply made a convenience of him to vent her spite upon Tom Sawyer.
+He was far from hating Tom the less when this thought occurred to him.
+He wished there was some way to get that boy into trouble without much
+risk to himself. Tom's spelling-book fell under his eye. Here was his
+opportunity. He gratefully opened to the lesson for the afternoon and
+poured ink upon the page.
+
+Becky, glancing in at a window behind him at the moment, saw the act,
+and moved on, without discovering herself. She started homeward, now,
+intending to find Tom and tell him; Tom would be thankful and their
+troubles would be healed. Before she was half way home, however, she
+had changed her mind. The thought of Tom's treatment of her when she
+was talking about her picnic came scorching back and filled her with
+shame. She resolved to let him get whipped on the damaged
+spelling-book's account, and to hate him forever, into the bargain.
+
+
+
+CHAPTER XIX
+
+TOM arrived at home in a dreary mood, and the first thing his aunt
+said to him showed him that he had brought his sorrows to an
+unpromising market:
+
+"Tom, I've a notion to skin you alive!"
+
+"Auntie, what have I done?"
+
+"Well, you've done enough. Here I go over to Sereny Harper, like an
+old softy, expecting I'm going to make her believe all that rubbage
+about that dream, when lo and behold you she'd found out from Joe that
+you was over here and heard all the talk we had that night. Tom, I
+don't know what is to become of a boy that will act like that. It makes
+me feel so bad to think you could let me go to Sereny Harper and make
+such a fool of myself and never say a word."
+
+This was a new aspect of the thing. His smartness of the morning had
+seemed to Tom a good joke before, and very ingenious. It merely looked
+mean and shabby now. He hung his head and could not think of anything
+to say for a moment. Then he said:
+
+"Auntie, I wish I hadn't done it--but I didn't think."
+
+"Oh, child, you never think. You never think of anything but your own
+selfishness. You could think to come all the way over here from
+Jackson's Island in the night to laugh at our troubles, and you could
+think to fool me with a lie about a dream; but you couldn't ever think
+to pity us and save us from sorrow."
+
+"Auntie, I know now it was mean, but I didn't mean to be mean. I
+didn't, honest. And besides, I didn't come over here to laugh at you
+that night."
+
+"What did you come for, then?"
+
+"It was to tell you not to be uneasy about us, because we hadn't got
+drownded."
+
+"Tom, Tom, I would be the thankfullest soul in this world if I could
+believe you ever had as good a thought as that, but you know you never
+did--and I know it, Tom."
+
+"Indeed and 'deed I did, auntie--I wish I may never stir if I didn't."
+
+"Oh, Tom, don't lie--don't do it. It only makes things a hundred times
+worse."
+
+"It ain't a lie, auntie; it's the truth. I wanted to keep you from
+grieving--that was all that made me come."
+
+"I'd give the whole world to believe that--it would cover up a power
+of sins, Tom. I'd 'most be glad you'd run off and acted so bad. But it
+ain't reasonable; because, why didn't you tell me, child?"
+
+"Why, you see, when you got to talking about the funeral, I just got
+all full of the idea of our coming and hiding in the church, and I
+couldn't somehow bear to spoil it. So I just put the bark back in my
+pocket and kept mum."
+
+"What bark?"
+
+"The bark I had wrote on to tell you we'd gone pirating. I wish, now,
+you'd waked up when I kissed you--I do, honest."
+
+The hard lines in his aunt's face relaxed and a sudden tenderness
+dawned in her eyes.
+
+"DID you kiss me, Tom?"
+
+"Why, yes, I did."
+
+"Are you sure you did, Tom?"
+
+"Why, yes, I did, auntie--certain sure."
+
+"What did you kiss me for, Tom?"
+
+"Because I loved you so, and you laid there moaning and I was so sorry."
+
+The words sounded like truth. The old lady could not hide a tremor in
+her voice when she said:
+
+"Kiss me again, Tom!--and be off with you to school, now, and don't
+bother me any more."
+
+The moment he was gone, she ran to a closet and got out the ruin of a
+jacket which Tom had gone pirating in. Then she stopped, with it in her
+hand, and said to herself:
+
+"No, I don't dare. Poor boy, I reckon he's lied about it--but it's a
+blessed, blessed lie, there's such a comfort come from it. I hope the
+Lord--I KNOW the Lord will forgive him, because it was such
+goodheartedness in him to tell it. But I don't want to find out it's a
+lie. I won't look."
+
+She put the jacket away, and stood by musing a minute. Twice she put
+out her hand to take the garment again, and twice she refrained. Once
+more she ventured, and this time she fortified herself with the
+thought: "It's a good lie--it's a good lie--I won't let it grieve me."
+So she sought the jacket pocket. A moment later she was reading Tom's
+piece of bark through flowing tears and saying: "I could forgive the
+boy, now, if he'd committed a million sins!"
+
+
+
+CHAPTER XX
+
+THERE was something about Aunt Polly's manner, when she kissed Tom,
+that swept away his low spirits and made him lighthearted and happy
+again. He started to school and had the luck of coming upon Becky
+Thatcher at the head of Meadow Lane. His mood always determined his
+manner. Without a moment's hesitation he ran to her and said:
+
+"I acted mighty mean to-day, Becky, and I'm so sorry. I won't ever,
+ever do that way again, as long as ever I live--please make up, won't
+you?"
+
+The girl stopped and looked him scornfully in the face:
+
+"I'll thank you to keep yourself TO yourself, Mr. Thomas Sawyer. I'll
+never speak to you again."
+
+She tossed her head and passed on. Tom was so stunned that he had not
+even presence of mind enough to say "Who cares, Miss Smarty?" until the
+right time to say it had gone by. So he said nothing. But he was in a
+fine rage, nevertheless. He moped into the schoolyard wishing she were
+a boy, and imagining how he would trounce her if she were. He presently
+encountered her and delivered a stinging remark as he passed. She
+hurled one in return, and the angry breach was complete. It seemed to
+Becky, in her hot resentment, that she could hardly wait for school to
+"take in," she was so impatient to see Tom flogged for the injured
+spelling-book. If she had had any lingering notion of exposing Alfred
+Temple, Tom's offensive fling had driven it entirely away.
+
+Poor girl, she did not know how fast she was nearing trouble herself.
+The master, Mr. Dobbins, had reached middle age with an unsatisfied
+ambition. The darling of his desires was, to be a doctor, but poverty
+had decreed that he should be nothing higher than a village
+schoolmaster. Every day he took a mysterious book out of his desk and
+absorbed himself in it at times when no classes were reciting. He kept
+that book under lock and key. There was not an urchin in school but was
+perishing to have a glimpse of it, but the chance never came. Every boy
+and girl had a theory about the nature of that book; but no two
+theories were alike, and there was no way of getting at the facts in
+the case. Now, as Becky was passing by the desk, which stood near the
+door, she noticed that the key was in the lock! It was a precious
+moment. She glanced around; found herself alone, and the next instant
+she had the book in her hands. The title-page--Professor Somebody's
+ANATOMY--carried no information to her mind; so she began to turn the
+leaves. She came at once upon a handsomely engraved and colored
+frontispiece--a human figure, stark naked. At that moment a shadow fell
+on the page and Tom Sawyer stepped in at the door and caught a glimpse
+of the picture. Becky snatched at the book to close it, and had the
+hard luck to tear the pictured page half down the middle. She thrust
+the volume into the desk, turned the key, and burst out crying with
+shame and vexation.
+
+"Tom Sawyer, you are just as mean as you can be, to sneak up on a
+person and look at what they're looking at."
+
+"How could I know you was looking at anything?"
+
+"You ought to be ashamed of yourself, Tom Sawyer; you know you're
+going to tell on me, and oh, what shall I do, what shall I do! I'll be
+whipped, and I never was whipped in school."
+
+Then she stamped her little foot and said:
+
+"BE so mean if you want to! I know something that's going to happen.
+You just wait and you'll see! Hateful, hateful, hateful!"--and she
+flung out of the house with a new explosion of crying.
+
+Tom stood still, rather flustered by this onslaught. Presently he said
+to himself:
+
+"What a curious kind of a fool a girl is! Never been licked in school!
+Shucks! What's a licking! That's just like a girl--they're so
+thin-skinned and chicken-hearted. Well, of course I ain't going to tell
+old Dobbins on this little fool, because there's other ways of getting
+even on her, that ain't so mean; but what of it? Old Dobbins will ask
+who it was tore his book. Nobody'll answer. Then he'll do just the way
+he always does--ask first one and then t'other, and when he comes to the
+right girl he'll know it, without any telling. Girls' faces always tell
+on them. They ain't got any backbone. She'll get licked. Well, it's a
+kind of a tight place for Becky Thatcher, because there ain't any way
+out of it." Tom conned the thing a moment longer, and then added: "All
+right, though; she'd like to see me in just such a fix--let her sweat it
+out!"
+
+Tom joined the mob of skylarking scholars outside. In a few moments
+the master arrived and school "took in." Tom did not feel a strong
+interest in his studies. Every time he stole a glance at the girls'
+side of the room Becky's face troubled him. Considering all things, he
+did not want to pity her, and yet it was all he could do to help it. He
+could get up no exultation that was really worthy the name. Presently
+the spelling-book discovery was made, and Tom's mind was entirely full
+of his own matters for a while after that. Becky roused up from her
+lethargy of distress and showed good interest in the proceedings. She
+did not expect that Tom could get out of his trouble by denying that he
+spilt the ink on the book himself; and she was right. The denial only
+seemed to make the thing worse for Tom. Becky supposed she would be
+glad of that, and she tried to believe she was glad of it, but she
+found she was not certain. When the worst came to the worst, she had an
+impulse to get up and tell on Alfred Temple, but she made an effort and
+forced herself to keep still--because, said she to herself, "he'll tell
+about me tearing the picture sure. I wouldn't say a word, not to save
+his life!"
+
+Tom took his whipping and went back to his seat not at all
+broken-hearted, for he thought it was possible that he had unknowingly
+upset the ink on the spelling-book himself, in some skylarking bout--he
+had denied it for form's sake and because it was custom, and had stuck
+to the denial from principle.
+
+A whole hour drifted by, the master sat nodding in his throne, the air
+was drowsy with the hum of study. By and by, Mr. Dobbins straightened
+himself up, yawned, then unlocked his desk, and reached for his book,
+but seemed undecided whether to take it out or leave it. Most of the
+pupils glanced up languidly, but there were two among them that watched
+his movements with intent eyes. Mr. Dobbins fingered his book absently
+for a while, then took it out and settled himself in his chair to read!
+Tom shot a glance at Becky. He had seen a hunted and helpless rabbit
+look as she did, with a gun levelled at its head. Instantly he forgot
+his quarrel with her. Quick--something must be done! done in a flash,
+too! But the very imminence of the emergency paralyzed his invention.
+Good!--he had an inspiration! He would run and snatch the book, spring
+through the door and fly. But his resolution shook for one little
+instant, and the chance was lost--the master opened the volume. If Tom
+only had the wasted opportunity back again! Too late. There was no help
+for Becky now, he said. The next moment the master faced the school.
+Every eye sank under his gaze. There was that in it which smote even
+the innocent with fear. There was silence while one might count ten
+--the master was gathering his wrath. Then he spoke: "Who tore this book?"
+
+There was not a sound. One could have heard a pin drop. The stillness
+continued; the master searched face after face for signs of guilt.
+
+"Benjamin Rogers, did you tear this book?"
+
+A denial. Another pause.
+
+"Joseph Harper, did you?"
+
+Another denial. Tom's uneasiness grew more and more intense under the
+slow torture of these proceedings. The master scanned the ranks of
+boys--considered a while, then turned to the girls:
+
+"Amy Lawrence?"
+
+A shake of the head.
+
+"Gracie Miller?"
+
+The same sign.
+
+"Susan Harper, did you do this?"
+
+Another negative. The next girl was Becky Thatcher. Tom was trembling
+from head to foot with excitement and a sense of the hopelessness of
+the situation.
+
+"Rebecca Thatcher" [Tom glanced at her face--it was white with terror]
+--"did you tear--no, look me in the face" [her hands rose in appeal]
+--"did you tear this book?"
+
+A thought shot like lightning through Tom's brain. He sprang to his
+feet and shouted--"I done it!"
+
+The school stared in perplexity at this incredible folly. Tom stood a
+moment, to gather his dismembered faculties; and when he stepped
+forward to go to his punishment the surprise, the gratitude, the
+adoration that shone upon him out of poor Becky's eyes seemed pay
+enough for a hundred floggings. Inspired by the splendor of his own
+act, he took without an outcry the most merciless flaying that even Mr.
+Dobbins had ever administered; and also received with indifference the
+added cruelty of a command to remain two hours after school should be
+dismissed--for he knew who would wait for him outside till his
+captivity was done, and not count the tedious time as loss, either.
+
+Tom went to bed that night planning vengeance against Alfred Temple;
+for with shame and repentance Becky had told him all, not forgetting
+her own treachery; but even the longing for vengeance had to give way,
+soon, to pleasanter musings, and he fell asleep at last with Becky's
+latest words lingering dreamily in his ear--
+
+"Tom, how COULD you be so noble!"
+
+
+
+CHAPTER XXI
+
+VACATION was approaching. The schoolmaster, always severe, grew
+severer and more exacting than ever, for he wanted the school to make a
+good showing on "Examination" day. His rod and his ferule were seldom
+idle now--at least among the smaller pupils. Only the biggest boys, and
+young ladies of eighteen and twenty, escaped lashing. Mr. Dobbins'
+lashings were very vigorous ones, too; for although he carried, under
+his wig, a perfectly bald and shiny head, he had only reached middle
+age, and there was no sign of feebleness in his muscle. As the great
+day approached, all the tyranny that was in him came to the surface; he
+seemed to take a vindictive pleasure in punishing the least
+shortcomings. The consequence was, that the smaller boys spent their
+days in terror and suffering and their nights in plotting revenge. They
+threw away no opportunity to do the master a mischief. But he kept
+ahead all the time. The retribution that followed every vengeful
+success was so sweeping and majestic that the boys always retired from
+the field badly worsted. At last they conspired together and hit upon a
+plan that promised a dazzling victory. They swore in the sign-painter's
+boy, told him the scheme, and asked his help. He had his own reasons
+for being delighted, for the master boarded in his father's family and
+had given the boy ample cause to hate him. The master's wife would go
+on a visit to the country in a few days, and there would be nothing to
+interfere with the plan; the master always prepared himself for great
+occasions by getting pretty well fuddled, and the sign-painter's boy
+said that when the dominie had reached the proper condition on
+Examination Evening he would "manage the thing" while he napped in his
+chair; then he would have him awakened at the right time and hurried
+away to school.
+
+In the fulness of time the interesting occasion arrived. At eight in
+the evening the schoolhouse was brilliantly lighted, and adorned with
+wreaths and festoons of foliage and flowers. The master sat throned in
+his great chair upon a raised platform, with his blackboard behind him.
+He was looking tolerably mellow. Three rows of benches on each side and
+six rows in front of him were occupied by the dignitaries of the town
+and by the parents of the pupils. To his left, back of the rows of
+citizens, was a spacious temporary platform upon which were seated the
+scholars who were to take part in the exercises of the evening; rows of
+small boys, washed and dressed to an intolerable state of discomfort;
+rows of gawky big boys; snowbanks of girls and young ladies clad in
+lawn and muslin and conspicuously conscious of their bare arms, their
+grandmothers' ancient trinkets, their bits of pink and blue ribbon and
+the flowers in their hair. All the rest of the house was filled with
+non-participating scholars.
+
+The exercises began. A very little boy stood up and sheepishly
+recited, "You'd scarce expect one of my age to speak in public on the
+stage," etc.--accompanying himself with the painfully exact and
+spasmodic gestures which a machine might have used--supposing the
+machine to be a trifle out of order. But he got through safely, though
+cruelly scared, and got a fine round of applause when he made his
+manufactured bow and retired.
+
+A little shamefaced girl lisped, "Mary had a little lamb," etc.,
+performed a compassion-inspiring curtsy, got her meed of applause, and
+sat down flushed and happy.
+
+Tom Sawyer stepped forward with conceited confidence and soared into
+the unquenchable and indestructible "Give me liberty or give me death"
+speech, with fine fury and frantic gesticulation, and broke down in the
+middle of it. A ghastly stage-fright seized him, his legs quaked under
+him and he was like to choke. True, he had the manifest sympathy of the
+house but he had the house's silence, too, which was even worse than
+its sympathy. The master frowned, and this completed the disaster. Tom
+struggled awhile and then retired, utterly defeated. There was a weak
+attempt at applause, but it died early.
+
+"The Boy Stood on the Burning Deck" followed; also "The Assyrian Came
+Down," and other declamatory gems. Then there were reading exercises,
+and a spelling fight. The meagre Latin class recited with honor. The
+prime feature of the evening was in order, now--original "compositions"
+by the young ladies. Each in her turn stepped forward to the edge of
+the platform, cleared her throat, held up her manuscript (tied with
+dainty ribbon), and proceeded to read, with labored attention to
+"expression" and punctuation. The themes were the same that had been
+illuminated upon similar occasions by their mothers before them, their
+grandmothers, and doubtless all their ancestors in the female line
+clear back to the Crusades. "Friendship" was one; "Memories of Other
+Days"; "Religion in History"; "Dream Land"; "The Advantages of
+Culture"; "Forms of Political Government Compared and Contrasted";
+"Melancholy"; "Filial Love"; "Heart Longings," etc., etc.
+
+A prevalent feature in these compositions was a nursed and petted
+melancholy; another was a wasteful and opulent gush of "fine language";
+another was a tendency to lug in by the ears particularly prized words
+and phrases until they were worn entirely out; and a peculiarity that
+conspicuously marked and marred them was the inveterate and intolerable
+sermon that wagged its crippled tail at the end of each and every one
+of them. No matter what the subject might be, a brain-racking effort
+was made to squirm it into some aspect or other that the moral and
+religious mind could contemplate with edification. The glaring
+insincerity of these sermons was not sufficient to compass the
+banishment of the fashion from the schools, and it is not sufficient
+to-day; it never will be sufficient while the world stands, perhaps.
+There is no school in all our land where the young ladies do not feel
+obliged to close their compositions with a sermon; and you will find
+that the sermon of the most frivolous and the least religious girl in
+the school is always the longest and the most relentlessly pious. But
+enough of this. Homely truth is unpalatable.
+
+Let us return to the "Examination." The first composition that was
+read was one entitled "Is this, then, Life?" Perhaps the reader can
+endure an extract from it:
+
+  "In the common walks of life, with what delightful
+   emotions does the youthful mind look forward to some
+   anticipated scene of festivity! Imagination is busy
+   sketching rose-tinted pictures of joy. In fancy, the
+   voluptuous votary of fashion sees herself amid the
+   festive throng, 'the observed of all observers.' Her
+   graceful form, arrayed in snowy robes, is whirling
+   through the mazes of the joyous dance; her eye is
+   brightest, her step is lightest in the gay assembly.
+
+  "In such delicious fancies time quickly glides by,
+   and the welcome hour arrives for her entrance into
+   the Elysian world, of which she has had such bright
+   dreams. How fairy-like does everything appear to
+   her enchanted vision! Each new scene is more charming
+   than the last. But after a while she finds that
+   beneath this goodly exterior, all is vanity, the
+   flattery which once charmed her soul, now grates
+   harshly upon her ear; the ball-room has lost its
+   charms; and with wasted health and imbittered heart,
+   she turns away with the conviction that earthly
+   pleasures cannot satisfy the longings of the soul!"
+
+And so forth and so on. There was a buzz of gratification from time to
+time during the reading, accompanied by whispered ejaculations of "How
+sweet!" "How eloquent!" "So true!" etc., and after the thing had closed
+with a peculiarly afflicting sermon the applause was enthusiastic.
+
+Then arose a slim, melancholy girl, whose face had the "interesting"
+paleness that comes of pills and indigestion, and read a "poem." Two
+stanzas of it will do:
+
+   "A MISSOURI MAIDEN'S FAREWELL TO ALABAMA
+
+   "Alabama, good-bye! I love thee well!
+      But yet for a while do I leave thee now!
+    Sad, yes, sad thoughts of thee my heart doth swell,
+      And burning recollections throng my brow!
+    For I have wandered through thy flowery woods;
+      Have roamed and read near Tallapoosa's stream;
+    Have listened to Tallassee's warring floods,
+      And wooed on Coosa's side Aurora's beam.
+
+   "Yet shame I not to bear an o'er-full heart,
+      Nor blush to turn behind my tearful eyes;
+    'Tis from no stranger land I now must part,
+      'Tis to no strangers left I yield these sighs.
+    Welcome and home were mine within this State,
+      Whose vales I leave--whose spires fade fast from me
+    And cold must be mine eyes, and heart, and tete,
+      When, dear Alabama! they turn cold on thee!"
+
+There were very few there who knew what "tete" meant, but the poem was
+very satisfactory, nevertheless.
+
+Next appeared a dark-complexioned, black-eyed, black-haired young
+lady, who paused an impressive moment, assumed a tragic expression, and
+began to read in a measured, solemn tone:
+
+  "A VISION
+
+   "Dark and tempestuous was night. Around the
+   throne on high not a single star quivered; but
+   the deep intonations of the heavy thunder
+   constantly vibrated upon the ear; whilst the
+   terrific lightning revelled in angry mood
+   through the cloudy chambers of heaven, seeming
+   to scorn the power exerted over its terror by
+   the illustrious Franklin! Even the boisterous
+   winds unanimously came forth from their mystic
+   homes, and blustered about as if to enhance by
+   their aid the wildness of the scene.
+
+   "At such a time, so dark, so dreary, for human
+   sympathy my very spirit sighed; but instead thereof,
+
+   "'My dearest friend, my counsellor, my comforter
+   and guide--My joy in grief, my second bliss
+   in joy,' came to my side. She moved like one of
+   those bright beings pictured in the sunny walks
+   of fancy's Eden by the romantic and young, a
+   queen of beauty unadorned save by her own
+   transcendent loveliness. So soft was her step, it
+   failed to make even a sound, and but for the
+   magical thrill imparted by her genial touch, as
+   other unobtrusive beauties, she would have glided
+   away un-perceived--unsought. A strange sadness
+   rested upon her features, like icy tears upon
+   the robe of December, as she pointed to the
+   contending elements without, and bade me contemplate
+   the two beings presented."
+
+This nightmare occupied some ten pages of manuscript and wound up with
+a sermon so destructive of all hope to non-Presbyterians that it took
+the first prize. This composition was considered to be the very finest
+effort of the evening. The mayor of the village, in delivering the
+prize to the author of it, made a warm speech in which he said that it
+was by far the most "eloquent" thing he had ever listened to, and that
+Daniel Webster himself might well be proud of it.
+
+It may be remarked, in passing, that the number of compositions in
+which the word "beauteous" was over-fondled, and human experience
+referred to as "life's page," was up to the usual average.
+
+Now the master, mellow almost to the verge of geniality, put his chair
+aside, turned his back to the audience, and began to draw a map of
+America on the blackboard, to exercise the geography class upon. But he
+made a sad business of it with his unsteady hand, and a smothered
+titter rippled over the house. He knew what the matter was, and set
+himself to right it. He sponged out lines and remade them; but he only
+distorted them more than ever, and the tittering was more pronounced.
+He threw his entire attention upon his work, now, as if determined not
+to be put down by the mirth. He felt that all eyes were fastened upon
+him; he imagined he was succeeding, and yet the tittering continued; it
+even manifestly increased. And well it might. There was a garret above,
+pierced with a scuttle over his head; and down through this scuttle
+came a cat, suspended around the haunches by a string; she had a rag
+tied about her head and jaws to keep her from mewing; as she slowly
+descended she curved upward and clawed at the string, she swung
+downward and clawed at the intangible air. The tittering rose higher
+and higher--the cat was within six inches of the absorbed teacher's
+head--down, down, a little lower, and she grabbed his wig with her
+desperate claws, clung to it, and was snatched up into the garret in an
+instant with her trophy still in her possession! And how the light did
+blaze abroad from the master's bald pate--for the sign-painter's boy
+had GILDED it!
+
+That broke up the meeting. The boys were avenged. Vacation had come.
+
+   NOTE:--The pretended "compositions" quoted in
+   this chapter are taken without alteration from a
+   volume entitled "Prose and Poetry, by a Western
+   Lady"--but they are exactly and precisely after
+   the schoolgirl pattern, and hence are much
+   happier than any mere imitations could be.
+
+
+
+CHAPTER XXII
+
+TOM joined the new order of Cadets of Temperance, being attracted by
+the showy character of their "regalia." He promised to abstain from
+smoking, chewing, and profanity as long as he remained a member. Now he
+found out a new thing--namely, that to promise not to do a thing is the
+surest way in the world to make a body want to go and do that very
+thing. Tom soon found himself tormented with a desire to drink and
+swear; the desire grew to be so intense that nothing but the hope of a
+chance to display himself in his red sash kept him from withdrawing
+from the order. Fourth of July was coming; but he soon gave that up
+--gave it up before he had worn his shackles over forty-eight hours--and
+fixed his hopes upon old Judge Frazer, justice of the peace, who was
+apparently on his deathbed and would have a big public funeral, since
+he was so high an official. During three days Tom was deeply concerned
+about the Judge's condition and hungry for news of it. Sometimes his
+hopes ran high--so high that he would venture to get out his regalia
+and practise before the looking-glass. But the Judge had a most
+discouraging way of fluctuating. At last he was pronounced upon the
+mend--and then convalescent. Tom was disgusted; and felt a sense of
+injury, too. He handed in his resignation at once--and that night the
+Judge suffered a relapse and died. Tom resolved that he would never
+trust a man like that again.
+
+The funeral was a fine thing. The Cadets paraded in a style calculated
+to kill the late member with envy. Tom was a free boy again, however
+--there was something in that. He could drink and swear, now--but found
+to his surprise that he did not want to. The simple fact that he could,
+took the desire away, and the charm of it.
+
+Tom presently wondered to find that his coveted vacation was beginning
+to hang a little heavily on his hands.
+
+He attempted a diary--but nothing happened during three days, and so
+he abandoned it.
+
+The first of all the negro minstrel shows came to town, and made a
+sensation. Tom and Joe Harper got up a band of performers and were
+happy for two days.
+
+Even the Glorious Fourth was in some sense a failure, for it rained
+hard, there was no procession in consequence, and the greatest man in
+the world (as Tom supposed), Mr. Benton, an actual United States
+Senator, proved an overwhelming disappointment--for he was not
+twenty-five feet high, nor even anywhere in the neighborhood of it.
+
+A circus came. The boys played circus for three days afterward in
+tents made of rag carpeting--admission, three pins for boys, two for
+girls--and then circusing was abandoned.
+
+A phrenologist and a mesmerizer came--and went again and left the
+village duller and drearier than ever.
+
+There were some boys-and-girls' parties, but they were so few and so
+delightful that they only made the aching voids between ache the harder.
+
+Becky Thatcher was gone to her Constantinople home to stay with her
+parents during vacation--so there was no bright side to life anywhere.
+
+The dreadful secret of the murder was a chronic misery. It was a very
+cancer for permanency and pain.
+
+Then came the measles.
+
+During two long weeks Tom lay a prisoner, dead to the world and its
+happenings. He was very ill, he was interested in nothing. When he got
+upon his feet at last and moved feebly down-town, a melancholy change
+had come over everything and every creature. There had been a
+"revival," and everybody had "got religion," not only the adults, but
+even the boys and girls. Tom went about, hoping against hope for the
+sight of one blessed sinful face, but disappointment crossed him
+everywhere. He found Joe Harper studying a Testament, and turned sadly
+away from the depressing spectacle. He sought Ben Rogers, and found him
+visiting the poor with a basket of tracts. He hunted up Jim Hollis, who
+called his attention to the precious blessing of his late measles as a
+warning. Every boy he encountered added another ton to his depression;
+and when, in desperation, he flew for refuge at last to the bosom of
+Huckleberry Finn and was received with a Scriptural quotation, his
+heart broke and he crept home and to bed realizing that he alone of all
+the town was lost, forever and forever.
+
+And that night there came on a terrific storm, with driving rain,
+awful claps of thunder and blinding sheets of lightning. He covered his
+head with the bedclothes and waited in a horror of suspense for his
+doom; for he had not the shadow of a doubt that all this hubbub was
+about him. He believed he had taxed the forbearance of the powers above
+to the extremity of endurance and that this was the result. It might
+have seemed to him a waste of pomp and ammunition to kill a bug with a
+battery of artillery, but there seemed nothing incongruous about the
+getting up such an expensive thunderstorm as this to knock the turf
+from under an insect like himself.
+
+By and by the tempest spent itself and died without accomplishing its
+object. The boy's first impulse was to be grateful, and reform. His
+second was to wait--for there might not be any more storms.
+
+The next day the doctors were back; Tom had relapsed. The three weeks
+he spent on his back this time seemed an entire age. When he got abroad
+at last he was hardly grateful that he had been spared, remembering how
+lonely was his estate, how companionless and forlorn he was. He drifted
+listlessly down the street and found Jim Hollis acting as judge in a
+juvenile court that was trying a cat for murder, in the presence of her
+victim, a bird. He found Joe Harper and Huck Finn up an alley eating a
+stolen melon. Poor lads! they--like Tom--had suffered a relapse.
+
+
+
+CHAPTER XXIII
+
+AT last the sleepy atmosphere was stirred--and vigorously: the murder
+trial came on in the court. It became the absorbing topic of village
+talk immediately. Tom could not get away from it. Every reference to
+the murder sent a shudder to his heart, for his troubled conscience and
+fears almost persuaded him that these remarks were put forth in his
+hearing as "feelers"; he did not see how he could be suspected of
+knowing anything about the murder, but still he could not be
+comfortable in the midst of this gossip. It kept him in a cold shiver
+all the time. He took Huck to a lonely place to have a talk with him.
+It would be some relief to unseal his tongue for a little while; to
+divide his burden of distress with another sufferer. Moreover, he
+wanted to assure himself that Huck had remained discreet.
+
+"Huck, have you ever told anybody about--that?"
+
+"'Bout what?"
+
+"You know what."
+
+"Oh--'course I haven't."
+
+"Never a word?"
+
+"Never a solitary word, so help me. What makes you ask?"
+
+"Well, I was afeard."
+
+"Why, Tom Sawyer, we wouldn't be alive two days if that got found out.
+YOU know that."
+
+Tom felt more comfortable. After a pause:
+
+"Huck, they couldn't anybody get you to tell, could they?"
+
+"Get me to tell? Why, if I wanted that half-breed devil to drownd me
+they could get me to tell. They ain't no different way."
+
+"Well, that's all right, then. I reckon we're safe as long as we keep
+mum. But let's swear again, anyway. It's more surer."
+
+"I'm agreed."
+
+So they swore again with dread solemnities.
+
+"What is the talk around, Huck? I've heard a power of it."
+
+"Talk? Well, it's just Muff Potter, Muff Potter, Muff Potter all the
+time. It keeps me in a sweat, constant, so's I want to hide som'ers."
+
+"That's just the same way they go on round me. I reckon he's a goner.
+Don't you feel sorry for him, sometimes?"
+
+"Most always--most always. He ain't no account; but then he hain't
+ever done anything to hurt anybody. Just fishes a little, to get money
+to get drunk on--and loafs around considerable; but lord, we all do
+that--leastways most of us--preachers and such like. But he's kind of
+good--he give me half a fish, once, when there warn't enough for two;
+and lots of times he's kind of stood by me when I was out of luck."
+
+"Well, he's mended kites for me, Huck, and knitted hooks on to my
+line. I wish we could get him out of there."
+
+"My! we couldn't get him out, Tom. And besides, 'twouldn't do any
+good; they'd ketch him again."
+
+"Yes--so they would. But I hate to hear 'em abuse him so like the
+dickens when he never done--that."
+
+"I do too, Tom. Lord, I hear 'em say he's the bloodiest looking
+villain in this country, and they wonder he wasn't ever hung before."
+
+"Yes, they talk like that, all the time. I've heard 'em say that if he
+was to get free they'd lynch him."
+
+"And they'd do it, too."
+
+The boys had a long talk, but it brought them little comfort. As the
+twilight drew on, they found themselves hanging about the neighborhood
+of the little isolated jail, perhaps with an undefined hope that
+something would happen that might clear away their difficulties. But
+nothing happened; there seemed to be no angels or fairies interested in
+this luckless captive.
+
+The boys did as they had often done before--went to the cell grating
+and gave Potter some tobacco and matches. He was on the ground floor
+and there were no guards.
+
+His gratitude for their gifts had always smote their consciences
+before--it cut deeper than ever, this time. They felt cowardly and
+treacherous to the last degree when Potter said:
+
+"You've been mighty good to me, boys--better'n anybody else in this
+town. And I don't forget it, I don't. Often I says to myself, says I,
+'I used to mend all the boys' kites and things, and show 'em where the
+good fishin' places was, and befriend 'em what I could, and now they've
+all forgot old Muff when he's in trouble; but Tom don't, and Huck
+don't--THEY don't forget him, says I, 'and I don't forget them.' Well,
+boys, I done an awful thing--drunk and crazy at the time--that's the
+only way I account for it--and now I got to swing for it, and it's
+right. Right, and BEST, too, I reckon--hope so, anyway. Well, we won't
+talk about that. I don't want to make YOU feel bad; you've befriended
+me. But what I want to say, is, don't YOU ever get drunk--then you won't
+ever get here. Stand a litter furder west--so--that's it; it's a prime
+comfort to see faces that's friendly when a body's in such a muck of
+trouble, and there don't none come here but yourn. Good friendly
+faces--good friendly faces. Git up on one another's backs and let me
+touch 'em. That's it. Shake hands--yourn'll come through the bars, but
+mine's too big. Little hands, and weak--but they've helped Muff Potter
+a power, and they'd help him more if they could."
+
+Tom went home miserable, and his dreams that night were full of
+horrors. The next day and the day after, he hung about the court-room,
+drawn by an almost irresistible impulse to go in, but forcing himself
+to stay out. Huck was having the same experience. They studiously
+avoided each other. Each wandered away, from time to time, but the same
+dismal fascination always brought them back presently. Tom kept his
+ears open when idlers sauntered out of the court-room, but invariably
+heard distressing news--the toils were closing more and more
+relentlessly around poor Potter. At the end of the second day the
+village talk was to the effect that Injun Joe's evidence stood firm and
+unshaken, and that there was not the slightest question as to what the
+jury's verdict would be.
+
+Tom was out late, that night, and came to bed through the window. He
+was in a tremendous state of excitement. It was hours before he got to
+sleep. All the village flocked to the court-house the next morning, for
+this was to be the great day. Both sexes were about equally represented
+in the packed audience. After a long wait the jury filed in and took
+their places; shortly afterward, Potter, pale and haggard, timid and
+hopeless, was brought in, with chains upon him, and seated where all
+the curious eyes could stare at him; no less conspicuous was Injun Joe,
+stolid as ever. There was another pause, and then the judge arrived and
+the sheriff proclaimed the opening of the court. The usual whisperings
+among the lawyers and gathering together of papers followed. These
+details and accompanying delays worked up an atmosphere of preparation
+that was as impressive as it was fascinating.
+
+Now a witness was called who testified that he found Muff Potter
+washing in the brook, at an early hour of the morning that the murder
+was discovered, and that he immediately sneaked away. After some
+further questioning, counsel for the prosecution said:
+
+"Take the witness."
+
+The prisoner raised his eyes for a moment, but dropped them again when
+his own counsel said:
+
+"I have no questions to ask him."
+
+The next witness proved the finding of the knife near the corpse.
+Counsel for the prosecution said:
+
+"Take the witness."
+
+"I have no questions to ask him," Potter's lawyer replied.
+
+A third witness swore he had often seen the knife in Potter's
+possession.
+
+"Take the witness."
+
+Counsel for Potter declined to question him. The faces of the audience
+began to betray annoyance. Did this attorney mean to throw away his
+client's life without an effort?
+
+Several witnesses deposed concerning Potter's guilty behavior when
+brought to the scene of the murder. They were allowed to leave the
+stand without being cross-questioned.
+
+Every detail of the damaging circumstances that occurred in the
+graveyard upon that morning which all present remembered so well was
+brought out by credible witnesses, but none of them were cross-examined
+by Potter's lawyer. The perplexity and dissatisfaction of the house
+expressed itself in murmurs and provoked a reproof from the bench.
+Counsel for the prosecution now said:
+
+"By the oaths of citizens whose simple word is above suspicion, we
+have fastened this awful crime, beyond all possibility of question,
+upon the unhappy prisoner at the bar. We rest our case here."
+
+A groan escaped from poor Potter, and he put his face in his hands and
+rocked his body softly to and fro, while a painful silence reigned in
+the court-room. Many men were moved, and many women's compassion
+testified itself in tears. Counsel for the defence rose and said:
+
+"Your honor, in our remarks at the opening of this trial, we
+foreshadowed our purpose to prove that our client did this fearful deed
+while under the influence of a blind and irresponsible delirium
+produced by drink. We have changed our mind. We shall not offer that
+plea." [Then to the clerk:] "Call Thomas Sawyer!"
+
+A puzzled amazement awoke in every face in the house, not even
+excepting Potter's. Every eye fastened itself with wondering interest
+upon Tom as he rose and took his place upon the stand. The boy looked
+wild enough, for he was badly scared. The oath was administered.
+
+"Thomas Sawyer, where were you on the seventeenth of June, about the
+hour of midnight?"
+
+Tom glanced at Injun Joe's iron face and his tongue failed him. The
+audience listened breathless, but the words refused to come. After a
+few moments, however, the boy got a little of his strength back, and
+managed to put enough of it into his voice to make part of the house
+hear:
+
+"In the graveyard!"
+
+"A little bit louder, please. Don't be afraid. You were--"
+
+"In the graveyard."
+
+A contemptuous smile flitted across Injun Joe's face.
+
+"Were you anywhere near Horse Williams' grave?"
+
+"Yes, sir."
+
+"Speak up--just a trifle louder. How near were you?"
+
+"Near as I am to you."
+
+"Were you hidden, or not?"
+
+"I was hid."
+
+"Where?"
+
+"Behind the elms that's on the edge of the grave."
+
+Injun Joe gave a barely perceptible start.
+
+"Any one with you?"
+
+"Yes, sir. I went there with--"
+
+"Wait--wait a moment. Never mind mentioning your companion's name. We
+will produce him at the proper time. Did you carry anything there with
+you."
+
+Tom hesitated and looked confused.
+
+"Speak out, my boy--don't be diffident. The truth is always
+respectable. What did you take there?"
+
+"Only a--a--dead cat."
+
+There was a ripple of mirth, which the court checked.
+
+"We will produce the skeleton of that cat. Now, my boy, tell us
+everything that occurred--tell it in your own way--don't skip anything,
+and don't be afraid."
+
+Tom began--hesitatingly at first, but as he warmed to his subject his
+words flowed more and more easily; in a little while every sound ceased
+but his own voice; every eye fixed itself upon him; with parted lips
+and bated breath the audience hung upon his words, taking no note of
+time, rapt in the ghastly fascinations of the tale. The strain upon
+pent emotion reached its climax when the boy said:
+
+"--and as the doctor fetched the board around and Muff Potter fell,
+Injun Joe jumped with the knife and--"
+
+Crash! Quick as lightning the half-breed sprang for a window, tore his
+way through all opposers, and was gone!
+
+
+
+CHAPTER XXIV
+
+TOM was a glittering hero once more--the pet of the old, the envy of
+the young. His name even went into immortal print, for the village
+paper magnified him. There were some that believed he would be
+President, yet, if he escaped hanging.
+
+As usual, the fickle, unreasoning world took Muff Potter to its bosom
+and fondled him as lavishly as it had abused him before. But that sort
+of conduct is to the world's credit; therefore it is not well to find
+fault with it.
+
+Tom's days were days of splendor and exultation to him, but his nights
+were seasons of horror. Injun Joe infested all his dreams, and always
+with doom in his eye. Hardly any temptation could persuade the boy to
+stir abroad after nightfall. Poor Huck was in the same state of
+wretchedness and terror, for Tom had told the whole story to the lawyer
+the night before the great day of the trial, and Huck was sore afraid
+that his share in the business might leak out, yet, notwithstanding
+Injun Joe's flight had saved him the suffering of testifying in court.
+The poor fellow had got the attorney to promise secrecy, but what of
+that? Since Tom's harassed conscience had managed to drive him to the
+lawyer's house by night and wring a dread tale from lips that had been
+sealed with the dismalest and most formidable of oaths, Huck's
+confidence in the human race was well-nigh obliterated.
+
+Daily Muff Potter's gratitude made Tom glad he had spoken; but nightly
+he wished he had sealed up his tongue.
+
+Half the time Tom was afraid Injun Joe would never be captured; the
+other half he was afraid he would be. He felt sure he never could draw
+a safe breath again until that man was dead and he had seen the corpse.
+
+Rewards had been offered, the country had been scoured, but no Injun
+Joe was found. One of those omniscient and awe-inspiring marvels, a
+detective, came up from St. Louis, moused around, shook his head,
+looked wise, and made that sort of astounding success which members of
+that craft usually achieve. That is to say, he "found a clew." But you
+can't hang a "clew" for murder, and so after that detective had got
+through and gone home, Tom felt just as insecure as he was before.
+
+The slow days drifted on, and each left behind it a slightly lightened
+weight of apprehension.
+
+
+
+CHAPTER XXV
+
+THERE comes a time in every rightly-constructed boy's life when he has
+a raging desire to go somewhere and dig for hidden treasure. This
+desire suddenly came upon Tom one day. He sallied out to find Joe
+Harper, but failed of success. Next he sought Ben Rogers; he had gone
+fishing. Presently he stumbled upon Huck Finn the Red-Handed. Huck
+would answer. Tom took him to a private place and opened the matter to
+him confidentially. Huck was willing. Huck was always willing to take a
+hand in any enterprise that offered entertainment and required no
+capital, for he had a troublesome superabundance of that sort of time
+which is not money. "Where'll we dig?" said Huck.
+
+"Oh, most anywhere."
+
+"Why, is it hid all around?"
+
+"No, indeed it ain't. It's hid in mighty particular places, Huck
+--sometimes on islands, sometimes in rotten chests under the end of a
+limb of an old dead tree, just where the shadow falls at midnight; but
+mostly under the floor in ha'nted houses."
+
+"Who hides it?"
+
+"Why, robbers, of course--who'd you reckon? Sunday-school
+sup'rintendents?"
+
+"I don't know. If 'twas mine I wouldn't hide it; I'd spend it and have
+a good time."
+
+"So would I. But robbers don't do that way. They always hide it and
+leave it there."
+
+"Don't they come after it any more?"
+
+"No, they think they will, but they generally forget the marks, or
+else they die. Anyway, it lays there a long time and gets rusty; and by
+and by somebody finds an old yellow paper that tells how to find the
+marks--a paper that's got to be ciphered over about a week because it's
+mostly signs and hy'roglyphics."
+
+"Hyro--which?"
+
+"Hy'roglyphics--pictures and things, you know, that don't seem to mean
+anything."
+
+"Have you got one of them papers, Tom?"
+
+"No."
+
+"Well then, how you going to find the marks?"
+
+"I don't want any marks. They always bury it under a ha'nted house or
+on an island, or under a dead tree that's got one limb sticking out.
+Well, we've tried Jackson's Island a little, and we can try it again
+some time; and there's the old ha'nted house up the Still-House branch,
+and there's lots of dead-limb trees--dead loads of 'em."
+
+"Is it under all of them?"
+
+"How you talk! No!"
+
+"Then how you going to know which one to go for?"
+
+"Go for all of 'em!"
+
+"Why, Tom, it'll take all summer."
+
+"Well, what of that? Suppose you find a brass pot with a hundred
+dollars in it, all rusty and gray, or rotten chest full of di'monds.
+How's that?"
+
+Huck's eyes glowed.
+
+"That's bully. Plenty bully enough for me. Just you gimme the hundred
+dollars and I don't want no di'monds."
+
+"All right. But I bet you I ain't going to throw off on di'monds. Some
+of 'em's worth twenty dollars apiece--there ain't any, hardly, but's
+worth six bits or a dollar."
+
+"No! Is that so?"
+
+"Cert'nly--anybody'll tell you so. Hain't you ever seen one, Huck?"
+
+"Not as I remember."
+
+"Oh, kings have slathers of them."
+
+"Well, I don' know no kings, Tom."
+
+"I reckon you don't. But if you was to go to Europe you'd see a raft
+of 'em hopping around."
+
+"Do they hop?"
+
+"Hop?--your granny! No!"
+
+"Well, what did you say they did, for?"
+
+"Shucks, I only meant you'd SEE 'em--not hopping, of course--what do
+they want to hop for?--but I mean you'd just see 'em--scattered around,
+you know, in a kind of a general way. Like that old humpbacked Richard."
+
+"Richard? What's his other name?"
+
+"He didn't have any other name. Kings don't have any but a given name."
+
+"No?"
+
+"But they don't."
+
+"Well, if they like it, Tom, all right; but I don't want to be a king
+and have only just a given name, like a nigger. But say--where you
+going to dig first?"
+
+"Well, I don't know. S'pose we tackle that old dead-limb tree on the
+hill t'other side of Still-House branch?"
+
+"I'm agreed."
+
+So they got a crippled pick and a shovel, and set out on their
+three-mile tramp. They arrived hot and panting, and threw themselves
+down in the shade of a neighboring elm to rest and have a smoke.
+
+"I like this," said Tom.
+
+"So do I."
+
+"Say, Huck, if we find a treasure here, what you going to do with your
+share?"
+
+"Well, I'll have pie and a glass of soda every day, and I'll go to
+every circus that comes along. I bet I'll have a gay time."
+
+"Well, ain't you going to save any of it?"
+
+"Save it? What for?"
+
+"Why, so as to have something to live on, by and by."
+
+"Oh, that ain't any use. Pap would come back to thish-yer town some
+day and get his claws on it if I didn't hurry up, and I tell you he'd
+clean it out pretty quick. What you going to do with yourn, Tom?"
+
+"I'm going to buy a new drum, and a sure-'nough sword, and a red
+necktie and a bull pup, and get married."
+
+"Married!"
+
+"That's it."
+
+"Tom, you--why, you ain't in your right mind."
+
+"Wait--you'll see."
+
+"Well, that's the foolishest thing you could do. Look at pap and my
+mother. Fight! Why, they used to fight all the time. I remember, mighty
+well."
+
+"That ain't anything. The girl I'm going to marry won't fight."
+
+"Tom, I reckon they're all alike. They'll all comb a body. Now you
+better think 'bout this awhile. I tell you you better. What's the name
+of the gal?"
+
+"It ain't a gal at all--it's a girl."
+
+"It's all the same, I reckon; some says gal, some says girl--both's
+right, like enough. Anyway, what's her name, Tom?"
+
+"I'll tell you some time--not now."
+
+"All right--that'll do. Only if you get married I'll be more lonesomer
+than ever."
+
+"No you won't. You'll come and live with me. Now stir out of this and
+we'll go to digging."
+
+They worked and sweated for half an hour. No result. They toiled
+another half-hour. Still no result. Huck said:
+
+"Do they always bury it as deep as this?"
+
+"Sometimes--not always. Not generally. I reckon we haven't got the
+right place."
+
+So they chose a new spot and began again. The labor dragged a little,
+but still they made progress. They pegged away in silence for some
+time. Finally Huck leaned on his shovel, swabbed the beaded drops from
+his brow with his sleeve, and said:
+
+"Where you going to dig next, after we get this one?"
+
+"I reckon maybe we'll tackle the old tree that's over yonder on
+Cardiff Hill back of the widow's."
+
+"I reckon that'll be a good one. But won't the widow take it away from
+us, Tom? It's on her land."
+
+"SHE take it away! Maybe she'd like to try it once. Whoever finds one
+of these hid treasures, it belongs to him. It don't make any difference
+whose land it's on."
+
+That was satisfactory. The work went on. By and by Huck said:
+
+"Blame it, we must be in the wrong place again. What do you think?"
+
+"It is mighty curious, Huck. I don't understand it. Sometimes witches
+interfere. I reckon maybe that's what's the trouble now."
+
+"Shucks! Witches ain't got no power in the daytime."
+
+"Well, that's so. I didn't think of that. Oh, I know what the matter
+is! What a blamed lot of fools we are! You got to find out where the
+shadow of the limb falls at midnight, and that's where you dig!"
+
+"Then consound it, we've fooled away all this work for nothing. Now
+hang it all, we got to come back in the night. It's an awful long way.
+Can you get out?"
+
+"I bet I will. We've got to do it to-night, too, because if somebody
+sees these holes they'll know in a minute what's here and they'll go
+for it."
+
+"Well, I'll come around and maow to-night."
+
+"All right. Let's hide the tools in the bushes."
+
+The boys were there that night, about the appointed time. They sat in
+the shadow waiting. It was a lonely place, and an hour made solemn by
+old traditions. Spirits whispered in the rustling leaves, ghosts lurked
+in the murky nooks, the deep baying of a hound floated up out of the
+distance, an owl answered with his sepulchral note. The boys were
+subdued by these solemnities, and talked little. By and by they judged
+that twelve had come; they marked where the shadow fell, and began to
+dig. Their hopes commenced to rise. Their interest grew stronger, and
+their industry kept pace with it. The hole deepened and still deepened,
+but every time their hearts jumped to hear the pick strike upon
+something, they only suffered a new disappointment. It was only a stone
+or a chunk. At last Tom said:
+
+"It ain't any use, Huck, we're wrong again."
+
+"Well, but we CAN'T be wrong. We spotted the shadder to a dot."
+
+"I know it, but then there's another thing."
+
+"What's that?".
+
+"Why, we only guessed at the time. Like enough it was too late or too
+early."
+
+Huck dropped his shovel.
+
+"That's it," said he. "That's the very trouble. We got to give this
+one up. We can't ever tell the right time, and besides this kind of
+thing's too awful, here this time of night with witches and ghosts
+a-fluttering around so. I feel as if something's behind me all the time;
+and I'm afeard to turn around, becuz maybe there's others in front
+a-waiting for a chance. I been creeping all over, ever since I got here."
+
+"Well, I've been pretty much so, too, Huck. They most always put in a
+dead man when they bury a treasure under a tree, to look out for it."
+
+"Lordy!"
+
+"Yes, they do. I've always heard that."
+
+"Tom, I don't like to fool around much where there's dead people. A
+body's bound to get into trouble with 'em, sure."
+
+"I don't like to stir 'em up, either. S'pose this one here was to
+stick his skull out and say something!"
+
+"Don't Tom! It's awful."
+
+"Well, it just is. Huck, I don't feel comfortable a bit."
+
+"Say, Tom, let's give this place up, and try somewheres else."
+
+"All right, I reckon we better."
+
+"What'll it be?"
+
+Tom considered awhile; and then said:
+
+"The ha'nted house. That's it!"
+
+"Blame it, I don't like ha'nted houses, Tom. Why, they're a dern sight
+worse'n dead people. Dead people might talk, maybe, but they don't come
+sliding around in a shroud, when you ain't noticing, and peep over your
+shoulder all of a sudden and grit their teeth, the way a ghost does. I
+couldn't stand such a thing as that, Tom--nobody could."
+
+"Yes, but, Huck, ghosts don't travel around only at night. They won't
+hender us from digging there in the daytime."
+
+"Well, that's so. But you know mighty well people don't go about that
+ha'nted house in the day nor the night."
+
+"Well, that's mostly because they don't like to go where a man's been
+murdered, anyway--but nothing's ever been seen around that house except
+in the night--just some blue lights slipping by the windows--no regular
+ghosts."
+
+"Well, where you see one of them blue lights flickering around, Tom,
+you can bet there's a ghost mighty close behind it. It stands to
+reason. Becuz you know that they don't anybody but ghosts use 'em."
+
+"Yes, that's so. But anyway they don't come around in the daytime, so
+what's the use of our being afeard?"
+
+"Well, all right. We'll tackle the ha'nted house if you say so--but I
+reckon it's taking chances."
+
+They had started down the hill by this time. There in the middle of
+the moonlit valley below them stood the "ha'nted" house, utterly
+isolated, its fences gone long ago, rank weeds smothering the very
+doorsteps, the chimney crumbled to ruin, the window-sashes vacant, a
+corner of the roof caved in. The boys gazed awhile, half expecting to
+see a blue light flit past a window; then talking in a low tone, as
+befitted the time and the circumstances, they struck far off to the
+right, to give the haunted house a wide berth, and took their way
+homeward through the woods that adorned the rearward side of Cardiff
+Hill.
+
+
+
+CHAPTER XXVI
+
+ABOUT noon the next day the boys arrived at the dead tree; they had
+come for their tools. Tom was impatient to go to the haunted house;
+Huck was measurably so, also--but suddenly said:
+
+"Lookyhere, Tom, do you know what day it is?"
+
+Tom mentally ran over the days of the week, and then quickly lifted
+his eyes with a startled look in them--
+
+"My! I never once thought of it, Huck!"
+
+"Well, I didn't neither, but all at once it popped onto me that it was
+Friday."
+
+"Blame it, a body can't be too careful, Huck. We might 'a' got into an
+awful scrape, tackling such a thing on a Friday."
+
+"MIGHT! Better say we WOULD! There's some lucky days, maybe, but
+Friday ain't."
+
+"Any fool knows that. I don't reckon YOU was the first that found it
+out, Huck."
+
+"Well, I never said I was, did I? And Friday ain't all, neither. I had
+a rotten bad dream last night--dreampt about rats."
+
+"No! Sure sign of trouble. Did they fight?"
+
+"No."
+
+"Well, that's good, Huck. When they don't fight it's only a sign that
+there's trouble around, you know. All we got to do is to look mighty
+sharp and keep out of it. We'll drop this thing for to-day, and play.
+Do you know Robin Hood, Huck?"
+
+"No. Who's Robin Hood?"
+
+"Why, he was one of the greatest men that was ever in England--and the
+best. He was a robber."
+
+"Cracky, I wisht I was. Who did he rob?"
+
+"Only sheriffs and bishops and rich people and kings, and such like.
+But he never bothered the poor. He loved 'em. He always divided up with
+'em perfectly square."
+
+"Well, he must 'a' been a brick."
+
+"I bet you he was, Huck. Oh, he was the noblest man that ever was.
+They ain't any such men now, I can tell you. He could lick any man in
+England, with one hand tied behind him; and he could take his yew bow
+and plug a ten-cent piece every time, a mile and a half."
+
+"What's a YEW bow?"
+
+"I don't know. It's some kind of a bow, of course. And if he hit that
+dime only on the edge he would set down and cry--and curse. But we'll
+play Robin Hood--it's nobby fun. I'll learn you."
+
+"I'm agreed."
+
+So they played Robin Hood all the afternoon, now and then casting a
+yearning eye down upon the haunted house and passing a remark about the
+morrow's prospects and possibilities there. As the sun began to sink
+into the west they took their way homeward athwart the long shadows of
+the trees and soon were buried from sight in the forests of Cardiff
+Hill.
+
+On Saturday, shortly after noon, the boys were at the dead tree again.
+They had a smoke and a chat in the shade, and then dug a little in
+their last hole, not with great hope, but merely because Tom said there
+were so many cases where people had given up a treasure after getting
+down within six inches of it, and then somebody else had come along and
+turned it up with a single thrust of a shovel. The thing failed this
+time, however, so the boys shouldered their tools and went away feeling
+that they had not trifled with fortune, but had fulfilled all the
+requirements that belong to the business of treasure-hunting.
+
+When they reached the haunted house there was something so weird and
+grisly about the dead silence that reigned there under the baking sun,
+and something so depressing about the loneliness and desolation of the
+place, that they were afraid, for a moment, to venture in. Then they
+crept to the door and took a trembling peep. They saw a weed-grown,
+floorless room, unplastered, an ancient fireplace, vacant windows, a
+ruinous staircase; and here, there, and everywhere hung ragged and
+abandoned cobwebs. They presently entered, softly, with quickened
+pulses, talking in whispers, ears alert to catch the slightest sound,
+and muscles tense and ready for instant retreat.
+
+In a little while familiarity modified their fears and they gave the
+place a critical and interested examination, rather admiring their own
+boldness, and wondering at it, too. Next they wanted to look up-stairs.
+This was something like cutting off retreat, but they got to daring
+each other, and of course there could be but one result--they threw
+their tools into a corner and made the ascent. Up there were the same
+signs of decay. In one corner they found a closet that promised
+mystery, but the promise was a fraud--there was nothing in it. Their
+courage was up now and well in hand. They were about to go down and
+begin work when--
+
+"Sh!" said Tom.
+
+"What is it?" whispered Huck, blanching with fright.
+
+"Sh!... There!... Hear it?"
+
+"Yes!... Oh, my! Let's run!"
+
+"Keep still! Don't you budge! They're coming right toward the door."
+
+The boys stretched themselves upon the floor with their eyes to
+knot-holes in the planking, and lay waiting, in a misery of fear.
+
+"They've stopped.... No--coming.... Here they are. Don't whisper
+another word, Huck. My goodness, I wish I was out of this!"
+
+Two men entered. Each boy said to himself: "There's the old deaf and
+dumb Spaniard that's been about town once or twice lately--never saw
+t'other man before."
+
+"T'other" was a ragged, unkempt creature, with nothing very pleasant
+in his face. The Spaniard was wrapped in a serape; he had bushy white
+whiskers; long white hair flowed from under his sombrero, and he wore
+green goggles. When they came in, "t'other" was talking in a low voice;
+they sat down on the ground, facing the door, with their backs to the
+wall, and the speaker continued his remarks. His manner became less
+guarded and his words more distinct as he proceeded:
+
+"No," said he, "I've thought it all over, and I don't like it. It's
+dangerous."
+
+"Dangerous!" grunted the "deaf and dumb" Spaniard--to the vast
+surprise of the boys. "Milksop!"
+
+This voice made the boys gasp and quake. It was Injun Joe's! There was
+silence for some time. Then Joe said:
+
+"What's any more dangerous than that job up yonder--but nothing's come
+of it."
+
+"That's different. Away up the river so, and not another house about.
+'Twon't ever be known that we tried, anyway, long as we didn't succeed."
+
+"Well, what's more dangerous than coming here in the daytime!--anybody
+would suspicion us that saw us."
+
+"I know that. But there warn't any other place as handy after that
+fool of a job. I want to quit this shanty. I wanted to yesterday, only
+it warn't any use trying to stir out of here, with those infernal boys
+playing over there on the hill right in full view."
+
+"Those infernal boys" quaked again under the inspiration of this
+remark, and thought how lucky it was that they had remembered it was
+Friday and concluded to wait a day. They wished in their hearts they
+had waited a year.
+
+The two men got out some food and made a luncheon. After a long and
+thoughtful silence, Injun Joe said:
+
+"Look here, lad--you go back up the river where you belong. Wait there
+till you hear from me. I'll take the chances on dropping into this town
+just once more, for a look. We'll do that 'dangerous' job after I've
+spied around a little and think things look well for it. Then for
+Texas! We'll leg it together!"
+
+This was satisfactory. Both men presently fell to yawning, and Injun
+Joe said:
+
+"I'm dead for sleep! It's your turn to watch."
+
+He curled down in the weeds and soon began to snore. His comrade
+stirred him once or twice and he became quiet. Presently the watcher
+began to nod; his head drooped lower and lower, both men began to snore
+now.
+
+The boys drew a long, grateful breath. Tom whispered:
+
+"Now's our chance--come!"
+
+Huck said:
+
+"I can't--I'd die if they was to wake."
+
+Tom urged--Huck held back. At last Tom rose slowly and softly, and
+started alone. But the first step he made wrung such a hideous creak
+from the crazy floor that he sank down almost dead with fright. He
+never made a second attempt. The boys lay there counting the dragging
+moments till it seemed to them that time must be done and eternity
+growing gray; and then they were grateful to note that at last the sun
+was setting.
+
+Now one snore ceased. Injun Joe sat up, stared around--smiled grimly
+upon his comrade, whose head was drooping upon his knees--stirred him
+up with his foot and said:
+
+"Here! YOU'RE a watchman, ain't you! All right, though--nothing's
+happened."
+
+"My! have I been asleep?"
+
+"Oh, partly, partly. Nearly time for us to be moving, pard. What'll we
+do with what little swag we've got left?"
+
+"I don't know--leave it here as we've always done, I reckon. No use to
+take it away till we start south. Six hundred and fifty in silver's
+something to carry."
+
+"Well--all right--it won't matter to come here once more."
+
+"No--but I'd say come in the night as we used to do--it's better."
+
+"Yes: but look here; it may be a good while before I get the right
+chance at that job; accidents might happen; 'tain't in such a very good
+place; we'll just regularly bury it--and bury it deep."
+
+"Good idea," said the comrade, who walked across the room, knelt down,
+raised one of the rearward hearth-stones and took out a bag that
+jingled pleasantly. He subtracted from it twenty or thirty dollars for
+himself and as much for Injun Joe, and passed the bag to the latter,
+who was on his knees in the corner, now, digging with his bowie-knife.
+
+The boys forgot all their fears, all their miseries in an instant.
+With gloating eyes they watched every movement. Luck!--the splendor of
+it was beyond all imagination! Six hundred dollars was money enough to
+make half a dozen boys rich! Here was treasure-hunting under the
+happiest auspices--there would not be any bothersome uncertainty as to
+where to dig. They nudged each other every moment--eloquent nudges and
+easily understood, for they simply meant--"Oh, but ain't you glad NOW
+we're here!"
+
+Joe's knife struck upon something.
+
+"Hello!" said he.
+
+"What is it?" said his comrade.
+
+"Half-rotten plank--no, it's a box, I believe. Here--bear a hand and
+we'll see what it's here for. Never mind, I've broke a hole."
+
+He reached his hand in and drew it out--
+
+"Man, it's money!"
+
+The two men examined the handful of coins. They were gold. The boys
+above were as excited as themselves, and as delighted.
+
+Joe's comrade said:
+
+"We'll make quick work of this. There's an old rusty pick over amongst
+the weeds in the corner the other side of the fireplace--I saw it a
+minute ago."
+
+He ran and brought the boys' pick and shovel. Injun Joe took the pick,
+looked it over critically, shook his head, muttered something to
+himself, and then began to use it. The box was soon unearthed. It was
+not very large; it was iron bound and had been very strong before the
+slow years had injured it. The men contemplated the treasure awhile in
+blissful silence.
+
+"Pard, there's thousands of dollars here," said Injun Joe.
+
+"'Twas always said that Murrel's gang used to be around here one
+summer," the stranger observed.
+
+"I know it," said Injun Joe; "and this looks like it, I should say."
+
+"Now you won't need to do that job."
+
+The half-breed frowned. Said he:
+
+"You don't know me. Least you don't know all about that thing. 'Tain't
+robbery altogether--it's REVENGE!" and a wicked light flamed in his
+eyes. "I'll need your help in it. When it's finished--then Texas. Go
+home to your Nance and your kids, and stand by till you hear from me."
+
+"Well--if you say so; what'll we do with this--bury it again?"
+
+"Yes. [Ravishing delight overhead.] NO! by the great Sachem, no!
+[Profound distress overhead.] I'd nearly forgot. That pick had fresh
+earth on it! [The boys were sick with terror in a moment.] What
+business has a pick and a shovel here? What business with fresh earth
+on them? Who brought them here--and where are they gone? Have you heard
+anybody?--seen anybody? What! bury it again and leave them to come and
+see the ground disturbed? Not exactly--not exactly. We'll take it to my
+den."
+
+"Why, of course! Might have thought of that before. You mean Number
+One?"
+
+"No--Number Two--under the cross. The other place is bad--too common."
+
+"All right. It's nearly dark enough to start."
+
+Injun Joe got up and went about from window to window cautiously
+peeping out. Presently he said:
+
+"Who could have brought those tools here? Do you reckon they can be
+up-stairs?"
+
+The boys' breath forsook them. Injun Joe put his hand on his knife,
+halted a moment, undecided, and then turned toward the stairway. The
+boys thought of the closet, but their strength was gone. The steps came
+creaking up the stairs--the intolerable distress of the situation woke
+the stricken resolution of the lads--they were about to spring for the
+closet, when there was a crash of rotten timbers and Injun Joe landed
+on the ground amid the debris of the ruined stairway. He gathered
+himself up cursing, and his comrade said:
+
+"Now what's the use of all that? If it's anybody, and they're up
+there, let them STAY there--who cares? If they want to jump down, now,
+and get into trouble, who objects? It will be dark in fifteen minutes
+--and then let them follow us if they want to. I'm willing. In my
+opinion, whoever hove those things in here caught a sight of us and
+took us for ghosts or devils or something. I'll bet they're running
+yet."
+
+Joe grumbled awhile; then he agreed with his friend that what daylight
+was left ought to be economized in getting things ready for leaving.
+Shortly afterward they slipped out of the house in the deepening
+twilight, and moved toward the river with their precious box.
+
+Tom and Huck rose up, weak but vastly relieved, and stared after them
+through the chinks between the logs of the house. Follow? Not they.
+They were content to reach ground again without broken necks, and take
+the townward track over the hill. They did not talk much. They were too
+much absorbed in hating themselves--hating the ill luck that made them
+take the spade and the pick there. But for that, Injun Joe never would
+have suspected. He would have hidden the silver with the gold to wait
+there till his "revenge" was satisfied, and then he would have had the
+misfortune to find that money turn up missing. Bitter, bitter luck that
+the tools were ever brought there!
+
+They resolved to keep a lookout for that Spaniard when he should come
+to town spying out for chances to do his revengeful job, and follow him
+to "Number Two," wherever that might be. Then a ghastly thought
+occurred to Tom.
+
+"Revenge? What if he means US, Huck!"
+
+"Oh, don't!" said Huck, nearly fainting.
+
+They talked it all over, and as they entered town they agreed to
+believe that he might possibly mean somebody else--at least that he
+might at least mean nobody but Tom, since only Tom had testified.
+
+Very, very small comfort it was to Tom to be alone in danger! Company
+would be a palpable improvement, he thought.
+
+
+
+CHAPTER XXVII
+
+THE adventure of the day mightily tormented Tom's dreams that night.
+Four times he had his hands on that rich treasure and four times it
+wasted to nothingness in his fingers as sleep forsook him and
+wakefulness brought back the hard reality of his misfortune. As he lay
+in the early morning recalling the incidents of his great adventure, he
+noticed that they seemed curiously subdued and far away--somewhat as if
+they had happened in another world, or in a time long gone by. Then it
+occurred to him that the great adventure itself must be a dream! There
+was one very strong argument in favor of this idea--namely, that the
+quantity of coin he had seen was too vast to be real. He had never seen
+as much as fifty dollars in one mass before, and he was like all boys
+of his age and station in life, in that he imagined that all references
+to "hundreds" and "thousands" were mere fanciful forms of speech, and
+that no such sums really existed in the world. He never had supposed
+for a moment that so large a sum as a hundred dollars was to be found
+in actual money in any one's possession. If his notions of hidden
+treasure had been analyzed, they would have been found to consist of a
+handful of real dimes and a bushel of vague, splendid, ungraspable
+dollars.
+
+But the incidents of his adventure grew sensibly sharper and clearer
+under the attrition of thinking them over, and so he presently found
+himself leaning to the impression that the thing might not have been a
+dream, after all. This uncertainty must be swept away. He would snatch
+a hurried breakfast and go and find Huck. Huck was sitting on the
+gunwale of a flatboat, listlessly dangling his feet in the water and
+looking very melancholy. Tom concluded to let Huck lead up to the
+subject. If he did not do it, then the adventure would be proved to
+have been only a dream.
+
+"Hello, Huck!"
+
+"Hello, yourself."
+
+Silence, for a minute.
+
+"Tom, if we'd 'a' left the blame tools at the dead tree, we'd 'a' got
+the money. Oh, ain't it awful!"
+
+"'Tain't a dream, then, 'tain't a dream! Somehow I most wish it was.
+Dog'd if I don't, Huck."
+
+"What ain't a dream?"
+
+"Oh, that thing yesterday. I been half thinking it was."
+
+"Dream! If them stairs hadn't broke down you'd 'a' seen how much dream
+it was! I've had dreams enough all night--with that patch-eyed Spanish
+devil going for me all through 'em--rot him!"
+
+"No, not rot him. FIND him! Track the money!"
+
+"Tom, we'll never find him. A feller don't have only one chance for
+such a pile--and that one's lost. I'd feel mighty shaky if I was to see
+him, anyway."
+
+"Well, so'd I; but I'd like to see him, anyway--and track him out--to
+his Number Two."
+
+"Number Two--yes, that's it. I been thinking 'bout that. But I can't
+make nothing out of it. What do you reckon it is?"
+
+"I dono. It's too deep. Say, Huck--maybe it's the number of a house!"
+
+"Goody!... No, Tom, that ain't it. If it is, it ain't in this
+one-horse town. They ain't no numbers here."
+
+"Well, that's so. Lemme think a minute. Here--it's the number of a
+room--in a tavern, you know!"
+
+"Oh, that's the trick! They ain't only two taverns. We can find out
+quick."
+
+"You stay here, Huck, till I come."
+
+Tom was off at once. He did not care to have Huck's company in public
+places. He was gone half an hour. He found that in the best tavern, No.
+2 had long been occupied by a young lawyer, and was still so occupied.
+In the less ostentatious house, No. 2 was a mystery. The
+tavern-keeper's young son said it was kept locked all the time, and he
+never saw anybody go into it or come out of it except at night; he did
+not know any particular reason for this state of things; had had some
+little curiosity, but it was rather feeble; had made the most of the
+mystery by entertaining himself with the idea that that room was
+"ha'nted"; had noticed that there was a light in there the night before.
+
+"That's what I've found out, Huck. I reckon that's the very No. 2
+we're after."
+
+"I reckon it is, Tom. Now what you going to do?"
+
+"Lemme think."
+
+Tom thought a long time. Then he said:
+
+"I'll tell you. The back door of that No. 2 is the door that comes out
+into that little close alley between the tavern and the old rattle trap
+of a brick store. Now you get hold of all the door-keys you can find,
+and I'll nip all of auntie's, and the first dark night we'll go there
+and try 'em. And mind you, keep a lookout for Injun Joe, because he
+said he was going to drop into town and spy around once more for a
+chance to get his revenge. If you see him, you just follow him; and if
+he don't go to that No. 2, that ain't the place."
+
+"Lordy, I don't want to foller him by myself!"
+
+"Why, it'll be night, sure. He mightn't ever see you--and if he did,
+maybe he'd never think anything."
+
+"Well, if it's pretty dark I reckon I'll track him. I dono--I dono.
+I'll try."
+
+"You bet I'll follow him, if it's dark, Huck. Why, he might 'a' found
+out he couldn't get his revenge, and be going right after that money."
+
+"It's so, Tom, it's so. I'll foller him; I will, by jingoes!"
+
+"Now you're TALKING! Don't you ever weaken, Huck, and I won't."
+
+
+
+CHAPTER XXVIII
+
+THAT night Tom and Huck were ready for their adventure. They hung
+about the neighborhood of the tavern until after nine, one watching the
+alley at a distance and the other the tavern door. Nobody entered the
+alley or left it; nobody resembling the Spaniard entered or left the
+tavern door. The night promised to be a fair one; so Tom went home with
+the understanding that if a considerable degree of darkness came on,
+Huck was to come and "maow," whereupon he would slip out and try the
+keys. But the night remained clear, and Huck closed his watch and
+retired to bed in an empty sugar hogshead about twelve.
+
+Tuesday the boys had the same ill luck. Also Wednesday. But Thursday
+night promised better. Tom slipped out in good season with his aunt's
+old tin lantern, and a large towel to blindfold it with. He hid the
+lantern in Huck's sugar hogshead and the watch began. An hour before
+midnight the tavern closed up and its lights (the only ones
+thereabouts) were put out. No Spaniard had been seen. Nobody had
+entered or left the alley. Everything was auspicious. The blackness of
+darkness reigned, the perfect stillness was interrupted only by
+occasional mutterings of distant thunder.
+
+Tom got his lantern, lit it in the hogshead, wrapped it closely in the
+towel, and the two adventurers crept in the gloom toward the tavern.
+Huck stood sentry and Tom felt his way into the alley. Then there was a
+season of waiting anxiety that weighed upon Huck's spirits like a
+mountain. He began to wish he could see a flash from the lantern--it
+would frighten him, but it would at least tell him that Tom was alive
+yet. It seemed hours since Tom had disappeared. Surely he must have
+fainted; maybe he was dead; maybe his heart had burst under terror and
+excitement. In his uneasiness Huck found himself drawing closer and
+closer to the alley; fearing all sorts of dreadful things, and
+momentarily expecting some catastrophe to happen that would take away
+his breath. There was not much to take away, for he seemed only able to
+inhale it by thimblefuls, and his heart would soon wear itself out, the
+way it was beating. Suddenly there was a flash of light and Tom came
+tearing by him: "Run!" said he; "run, for your life!"
+
+He needn't have repeated it; once was enough; Huck was making thirty
+or forty miles an hour before the repetition was uttered. The boys
+never stopped till they reached the shed of a deserted slaughter-house
+at the lower end of the village. Just as they got within its shelter
+the storm burst and the rain poured down. As soon as Tom got his breath
+he said:
+
+"Huck, it was awful! I tried two of the keys, just as soft as I could;
+but they seemed to make such a power of racket that I couldn't hardly
+get my breath I was so scared. They wouldn't turn in the lock, either.
+Well, without noticing what I was doing, I took hold of the knob, and
+open comes the door! It warn't locked! I hopped in, and shook off the
+towel, and, GREAT CAESAR'S GHOST!"
+
+"What!--what'd you see, Tom?"
+
+"Huck, I most stepped onto Injun Joe's hand!"
+
+"No!"
+
+"Yes! He was lying there, sound asleep on the floor, with his old
+patch on his eye and his arms spread out."
+
+"Lordy, what did you do? Did he wake up?"
+
+"No, never budged. Drunk, I reckon. I just grabbed that towel and
+started!"
+
+"I'd never 'a' thought of the towel, I bet!"
+
+"Well, I would. My aunt would make me mighty sick if I lost it."
+
+"Say, Tom, did you see that box?"
+
+"Huck, I didn't wait to look around. I didn't see the box, I didn't
+see the cross. I didn't see anything but a bottle and a tin cup on the
+floor by Injun Joe; yes, I saw two barrels and lots more bottles in the
+room. Don't you see, now, what's the matter with that ha'nted room?"
+
+"How?"
+
+"Why, it's ha'nted with whiskey! Maybe ALL the Temperance Taverns have
+got a ha'nted room, hey, Huck?"
+
+"Well, I reckon maybe that's so. Who'd 'a' thought such a thing? But
+say, Tom, now's a mighty good time to get that box, if Injun Joe's
+drunk."
+
+"It is, that! You try it!"
+
+Huck shuddered.
+
+"Well, no--I reckon not."
+
+"And I reckon not, Huck. Only one bottle alongside of Injun Joe ain't
+enough. If there'd been three, he'd be drunk enough and I'd do it."
+
+There was a long pause for reflection, and then Tom said:
+
+"Lookyhere, Huck, less not try that thing any more till we know Injun
+Joe's not in there. It's too scary. Now, if we watch every night, we'll
+be dead sure to see him go out, some time or other, and then we'll
+snatch that box quicker'n lightning."
+
+"Well, I'm agreed. I'll watch the whole night long, and I'll do it
+every night, too, if you'll do the other part of the job."
+
+"All right, I will. All you got to do is to trot up Hooper Street a
+block and maow--and if I'm asleep, you throw some gravel at the window
+and that'll fetch me."
+
+"Agreed, and good as wheat!"
+
+"Now, Huck, the storm's over, and I'll go home. It'll begin to be
+daylight in a couple of hours. You go back and watch that long, will
+you?"
+
+"I said I would, Tom, and I will. I'll ha'nt that tavern every night
+for a year! I'll sleep all day and I'll stand watch all night."
+
+"That's all right. Now, where you going to sleep?"
+
+"In Ben Rogers' hayloft. He lets me, and so does his pap's nigger man,
+Uncle Jake. I tote water for Uncle Jake whenever he wants me to, and
+any time I ask him he gives me a little something to eat if he can
+spare it. That's a mighty good nigger, Tom. He likes me, becuz I don't
+ever act as if I was above him. Sometime I've set right down and eat
+WITH him. But you needn't tell that. A body's got to do things when
+he's awful hungry he wouldn't want to do as a steady thing."
+
+"Well, if I don't want you in the daytime, I'll let you sleep. I won't
+come bothering around. Any time you see something's up, in the night,
+just skip right around and maow."
+
+
+
+CHAPTER XXIX
+
+THE first thing Tom heard on Friday morning was a glad piece of news
+--Judge Thatcher's family had come back to town the night before. Both
+Injun Joe and the treasure sunk into secondary importance for a moment,
+and Becky took the chief place in the boy's interest. He saw her and
+they had an exhausting good time playing "hi-spy" and "gully-keeper"
+with a crowd of their school-mates. The day was completed and crowned
+in a peculiarly satisfactory way: Becky teased her mother to appoint
+the next day for the long-promised and long-delayed picnic, and she
+consented. The child's delight was boundless; and Tom's not more
+moderate. The invitations were sent out before sunset, and straightway
+the young folks of the village were thrown into a fever of preparation
+and pleasurable anticipation. Tom's excitement enabled him to keep
+awake until a pretty late hour, and he had good hopes of hearing Huck's
+"maow," and of having his treasure to astonish Becky and the picnickers
+with, next day; but he was disappointed. No signal came that night.
+
+Morning came, eventually, and by ten or eleven o'clock a giddy and
+rollicking company were gathered at Judge Thatcher's, and everything
+was ready for a start. It was not the custom for elderly people to mar
+the picnics with their presence. The children were considered safe
+enough under the wings of a few young ladies of eighteen and a few
+young gentlemen of twenty-three or thereabouts. The old steam ferryboat
+was chartered for the occasion; presently the gay throng filed up the
+main street laden with provision-baskets. Sid was sick and had to miss
+the fun; Mary remained at home to entertain him. The last thing Mrs.
+Thatcher said to Becky, was:
+
+"You'll not get back till late. Perhaps you'd better stay all night
+with some of the girls that live near the ferry-landing, child."
+
+"Then I'll stay with Susy Harper, mamma."
+
+"Very well. And mind and behave yourself and don't be any trouble."
+
+Presently, as they tripped along, Tom said to Becky:
+
+"Say--I'll tell you what we'll do. 'Stead of going to Joe Harper's
+we'll climb right up the hill and stop at the Widow Douglas'. She'll
+have ice-cream! She has it most every day--dead loads of it. And she'll
+be awful glad to have us."
+
+"Oh, that will be fun!"
+
+Then Becky reflected a moment and said:
+
+"But what will mamma say?"
+
+"How'll she ever know?"
+
+The girl turned the idea over in her mind, and said reluctantly:
+
+"I reckon it's wrong--but--"
+
+"But shucks! Your mother won't know, and so what's the harm? All she
+wants is that you'll be safe; and I bet you she'd 'a' said go there if
+she'd 'a' thought of it. I know she would!"
+
+The Widow Douglas' splendid hospitality was a tempting bait. It and
+Tom's persuasions presently carried the day. So it was decided to say
+nothing anybody about the night's programme. Presently it occurred to
+Tom that maybe Huck might come this very night and give the signal. The
+thought took a deal of the spirit out of his anticipations. Still he
+could not bear to give up the fun at Widow Douglas'. And why should he
+give it up, he reasoned--the signal did not come the night before, so
+why should it be any more likely to come to-night? The sure fun of the
+evening outweighed the uncertain treasure; and, boy-like, he determined
+to yield to the stronger inclination and not allow himself to think of
+the box of money another time that day.
+
+Three miles below town the ferryboat stopped at the mouth of a woody
+hollow and tied up. The crowd swarmed ashore and soon the forest
+distances and craggy heights echoed far and near with shoutings and
+laughter. All the different ways of getting hot and tired were gone
+through with, and by-and-by the rovers straggled back to camp fortified
+with responsible appetites, and then the destruction of the good things
+began. After the feast there was a refreshing season of rest and chat
+in the shade of spreading oaks. By-and-by somebody shouted:
+
+"Who's ready for the cave?"
+
+Everybody was. Bundles of candles were procured, and straightway there
+was a general scamper up the hill. The mouth of the cave was up the
+hillside--an opening shaped like a letter A. Its massive oaken door
+stood unbarred. Within was a small chamber, chilly as an ice-house, and
+walled by Nature with solid limestone that was dewy with a cold sweat.
+It was romantic and mysterious to stand here in the deep gloom and look
+out upon the green valley shining in the sun. But the impressiveness of
+the situation quickly wore off, and the romping began again. The moment
+a candle was lighted there was a general rush upon the owner of it; a
+struggle and a gallant defence followed, but the candle was soon
+knocked down or blown out, and then there was a glad clamor of laughter
+and a new chase. But all things have an end. By-and-by the procession
+went filing down the steep descent of the main avenue, the flickering
+rank of lights dimly revealing the lofty walls of rock almost to their
+point of junction sixty feet overhead. This main avenue was not more
+than eight or ten feet wide. Every few steps other lofty and still
+narrower crevices branched from it on either hand--for McDougal's cave
+was but a vast labyrinth of crooked aisles that ran into each other and
+out again and led nowhere. It was said that one might wander days and
+nights together through its intricate tangle of rifts and chasms, and
+never find the end of the cave; and that he might go down, and down,
+and still down, into the earth, and it was just the same--labyrinth
+under labyrinth, and no end to any of them. No man "knew" the cave.
+That was an impossible thing. Most of the young men knew a portion of
+it, and it was not customary to venture much beyond this known portion.
+Tom Sawyer knew as much of the cave as any one.
+
+The procession moved along the main avenue some three-quarters of a
+mile, and then groups and couples began to slip aside into branch
+avenues, fly along the dismal corridors, and take each other by
+surprise at points where the corridors joined again. Parties were able
+to elude each other for the space of half an hour without going beyond
+the "known" ground.
+
+By-and-by, one group after another came straggling back to the mouth
+of the cave, panting, hilarious, smeared from head to foot with tallow
+drippings, daubed with clay, and entirely delighted with the success of
+the day. Then they were astonished to find that they had been taking no
+note of time and that night was about at hand. The clanging bell had
+been calling for half an hour. However, this sort of close to the day's
+adventures was romantic and therefore satisfactory. When the ferryboat
+with her wild freight pushed into the stream, nobody cared sixpence for
+the wasted time but the captain of the craft.
+
+Huck was already upon his watch when the ferryboat's lights went
+glinting past the wharf. He heard no noise on board, for the young
+people were as subdued and still as people usually are who are nearly
+tired to death. He wondered what boat it was, and why she did not stop
+at the wharf--and then he dropped her out of his mind and put his
+attention upon his business. The night was growing cloudy and dark. Ten
+o'clock came, and the noise of vehicles ceased, scattered lights began
+to wink out, all straggling foot-passengers disappeared, the village
+betook itself to its slumbers and left the small watcher alone with the
+silence and the ghosts. Eleven o'clock came, and the tavern lights were
+put out; darkness everywhere, now. Huck waited what seemed a weary long
+time, but nothing happened. His faith was weakening. Was there any use?
+Was there really any use? Why not give it up and turn in?
+
+A noise fell upon his ear. He was all attention in an instant. The
+alley door closed softly. He sprang to the corner of the brick store.
+The next moment two men brushed by him, and one seemed to have
+something under his arm. It must be that box! So they were going to
+remove the treasure. Why call Tom now? It would be absurd--the men
+would get away with the box and never be found again. No, he would
+stick to their wake and follow them; he would trust to the darkness for
+security from discovery. So communing with himself, Huck stepped out
+and glided along behind the men, cat-like, with bare feet, allowing
+them to keep just far enough ahead not to be invisible.
+
+They moved up the river street three blocks, then turned to the left
+up a cross-street. They went straight ahead, then, until they came to
+the path that led up Cardiff Hill; this they took. They passed by the
+old Welshman's house, half-way up the hill, without hesitating, and
+still climbed upward. Good, thought Huck, they will bury it in the old
+quarry. But they never stopped at the quarry. They passed on, up the
+summit. They plunged into the narrow path between the tall sumach
+bushes, and were at once hidden in the gloom. Huck closed up and
+shortened his distance, now, for they would never be able to see him.
+He trotted along awhile; then slackened his pace, fearing he was
+gaining too fast; moved on a piece, then stopped altogether; listened;
+no sound; none, save that he seemed to hear the beating of his own
+heart. The hooting of an owl came over the hill--ominous sound! But no
+footsteps. Heavens, was everything lost! He was about to spring with
+winged feet, when a man cleared his throat not four feet from him!
+Huck's heart shot into his throat, but he swallowed it again; and then
+he stood there shaking as if a dozen agues had taken charge of him at
+once, and so weak that he thought he must surely fall to the ground. He
+knew where he was. He knew he was within five steps of the stile
+leading into Widow Douglas' grounds. Very well, he thought, let them
+bury it there; it won't be hard to find.
+
+Now there was a voice--a very low voice--Injun Joe's:
+
+"Damn her, maybe she's got company--there's lights, late as it is."
+
+"I can't see any."
+
+This was that stranger's voice--the stranger of the haunted house. A
+deadly chill went to Huck's heart--this, then, was the "revenge" job!
+His thought was, to fly. Then he remembered that the Widow Douglas had
+been kind to him more than once, and maybe these men were going to
+murder her. He wished he dared venture to warn her; but he knew he
+didn't dare--they might come and catch him. He thought all this and
+more in the moment that elapsed between the stranger's remark and Injun
+Joe's next--which was--
+
+"Because the bush is in your way. Now--this way--now you see, don't
+you?"
+
+"Yes. Well, there IS company there, I reckon. Better give it up."
+
+"Give it up, and I just leaving this country forever! Give it up and
+maybe never have another chance. I tell you again, as I've told you
+before, I don't care for her swag--you may have it. But her husband was
+rough on me--many times he was rough on me--and mainly he was the
+justice of the peace that jugged me for a vagrant. And that ain't all.
+It ain't a millionth part of it! He had me HORSEWHIPPED!--horsewhipped
+in front of the jail, like a nigger!--with all the town looking on!
+HORSEWHIPPED!--do you understand? He took advantage of me and died. But
+I'll take it out of HER."
+
+"Oh, don't kill her! Don't do that!"
+
+"Kill? Who said anything about killing? I would kill HIM if he was
+here; but not her. When you want to get revenge on a woman you don't
+kill her--bosh! you go for her looks. You slit her nostrils--you notch
+her ears like a sow!"
+
+"By God, that's--"
+
+"Keep your opinion to yourself! It will be safest for you. I'll tie
+her to the bed. If she bleeds to death, is that my fault? I'll not cry,
+if she does. My friend, you'll help me in this thing--for MY sake
+--that's why you're here--I mightn't be able alone. If you flinch, I'll
+kill you. Do you understand that? And if I have to kill you, I'll kill
+her--and then I reckon nobody'll ever know much about who done this
+business."
+
+"Well, if it's got to be done, let's get at it. The quicker the
+better--I'm all in a shiver."
+
+"Do it NOW? And company there? Look here--I'll get suspicious of you,
+first thing you know. No--we'll wait till the lights are out--there's
+no hurry."
+
+Huck felt that a silence was going to ensue--a thing still more awful
+than any amount of murderous talk; so he held his breath and stepped
+gingerly back; planted his foot carefully and firmly, after balancing,
+one-legged, in a precarious way and almost toppling over, first on one
+side and then on the other. He took another step back, with the same
+elaboration and the same risks; then another and another, and--a twig
+snapped under his foot! His breath stopped and he listened. There was
+no sound--the stillness was perfect. His gratitude was measureless. Now
+he turned in his tracks, between the walls of sumach bushes--turned
+himself as carefully as if he were a ship--and then stepped quickly but
+cautiously along. When he emerged at the quarry he felt secure, and so
+he picked up his nimble heels and flew. Down, down he sped, till he
+reached the Welshman's. He banged at the door, and presently the heads
+of the old man and his two stalwart sons were thrust from windows.
+
+"What's the row there? Who's banging? What do you want?"
+
+"Let me in--quick! I'll tell everything."
+
+"Why, who are you?"
+
+"Huckleberry Finn--quick, let me in!"
+
+"Huckleberry Finn, indeed! It ain't a name to open many doors, I
+judge! But let him in, lads, and let's see what's the trouble."
+
+"Please don't ever tell I told you," were Huck's first words when he
+got in. "Please don't--I'd be killed, sure--but the widow's been good
+friends to me sometimes, and I want to tell--I WILL tell if you'll
+promise you won't ever say it was me."
+
+"By George, he HAS got something to tell, or he wouldn't act so!"
+exclaimed the old man; "out with it and nobody here'll ever tell, lad."
+
+Three minutes later the old man and his sons, well armed, were up the
+hill, and just entering the sumach path on tiptoe, their weapons in
+their hands. Huck accompanied them no further. He hid behind a great
+bowlder and fell to listening. There was a lagging, anxious silence,
+and then all of a sudden there was an explosion of firearms and a cry.
+
+Huck waited for no particulars. He sprang away and sped down the hill
+as fast as his legs could carry him.
+
+
+
+CHAPTER XXX
+
+AS the earliest suspicion of dawn appeared on Sunday morning, Huck
+came groping up the hill and rapped gently at the old Welshman's door.
+The inmates were asleep, but it was a sleep that was set on a
+hair-trigger, on account of the exciting episode of the night. A call
+came from a window:
+
+"Who's there!"
+
+Huck's scared voice answered in a low tone:
+
+"Please let me in! It's only Huck Finn!"
+
+"It's a name that can open this door night or day, lad!--and welcome!"
+
+These were strange words to the vagabond boy's ears, and the
+pleasantest he had ever heard. He could not recollect that the closing
+word had ever been applied in his case before. The door was quickly
+unlocked, and he entered. Huck was given a seat and the old man and his
+brace of tall sons speedily dressed themselves.
+
+"Now, my boy, I hope you're good and hungry, because breakfast will be
+ready as soon as the sun's up, and we'll have a piping hot one, too
+--make yourself easy about that! I and the boys hoped you'd turn up and
+stop here last night."
+
+"I was awful scared," said Huck, "and I run. I took out when the
+pistols went off, and I didn't stop for three mile. I've come now becuz
+I wanted to know about it, you know; and I come before daylight becuz I
+didn't want to run across them devils, even if they was dead."
+
+"Well, poor chap, you do look as if you'd had a hard night of it--but
+there's a bed here for you when you've had your breakfast. No, they
+ain't dead, lad--we are sorry enough for that. You see we knew right
+where to put our hands on them, by your description; so we crept along
+on tiptoe till we got within fifteen feet of them--dark as a cellar
+that sumach path was--and just then I found I was going to sneeze. It
+was the meanest kind of luck! I tried to keep it back, but no use
+--'twas bound to come, and it did come! I was in the lead with my pistol
+raised, and when the sneeze started those scoundrels a-rustling to get
+out of the path, I sung out, 'Fire boys!' and blazed away at the place
+where the rustling was. So did the boys. But they were off in a jiffy,
+those villains, and we after them, down through the woods. I judge we
+never touched them. They fired a shot apiece as they started, but their
+bullets whizzed by and didn't do us any harm. As soon as we lost the
+sound of their feet we quit chasing, and went down and stirred up the
+constables. They got a posse together, and went off to guard the river
+bank, and as soon as it is light the sheriff and a gang are going to
+beat up the woods. My boys will be with them presently. I wish we had
+some sort of description of those rascals--'twould help a good deal.
+But you couldn't see what they were like, in the dark, lad, I suppose?"
+
+"Oh yes; I saw them down-town and follered them."
+
+"Splendid! Describe them--describe them, my boy!"
+
+"One's the old deaf and dumb Spaniard that's ben around here once or
+twice, and t'other's a mean-looking, ragged--"
+
+"That's enough, lad, we know the men! Happened on them in the woods
+back of the widow's one day, and they slunk away. Off with you, boys,
+and tell the sheriff--get your breakfast to-morrow morning!"
+
+The Welshman's sons departed at once. As they were leaving the room
+Huck sprang up and exclaimed:
+
+"Oh, please don't tell ANYbody it was me that blowed on them! Oh,
+please!"
+
+"All right if you say it, Huck, but you ought to have the credit of
+what you did."
+
+"Oh no, no! Please don't tell!"
+
+When the young men were gone, the old Welshman said:
+
+"They won't tell--and I won't. But why don't you want it known?"
+
+Huck would not explain, further than to say that he already knew too
+much about one of those men and would not have the man know that he
+knew anything against him for the whole world--he would be killed for
+knowing it, sure.
+
+The old man promised secrecy once more, and said:
+
+"How did you come to follow these fellows, lad? Were they looking
+suspicious?"
+
+Huck was silent while he framed a duly cautious reply. Then he said:
+
+"Well, you see, I'm a kind of a hard lot,--least everybody says so,
+and I don't see nothing agin it--and sometimes I can't sleep much, on
+account of thinking about it and sort of trying to strike out a new way
+of doing. That was the way of it last night. I couldn't sleep, and so I
+come along up-street 'bout midnight, a-turning it all over, and when I
+got to that old shackly brick store by the Temperance Tavern, I backed
+up agin the wall to have another think. Well, just then along comes
+these two chaps slipping along close by me, with something under their
+arm, and I reckoned they'd stole it. One was a-smoking, and t'other one
+wanted a light; so they stopped right before me and the cigars lit up
+their faces and I see that the big one was the deaf and dumb Spaniard,
+by his white whiskers and the patch on his eye, and t'other one was a
+rusty, ragged-looking devil."
+
+"Could you see the rags by the light of the cigars?"
+
+This staggered Huck for a moment. Then he said:
+
+"Well, I don't know--but somehow it seems as if I did."
+
+"Then they went on, and you--"
+
+"Follered 'em--yes. That was it. I wanted to see what was up--they
+sneaked along so. I dogged 'em to the widder's stile, and stood in the
+dark and heard the ragged one beg for the widder, and the Spaniard
+swear he'd spile her looks just as I told you and your two--"
+
+"What! The DEAF AND DUMB man said all that!"
+
+Huck had made another terrible mistake! He was trying his best to keep
+the old man from getting the faintest hint of who the Spaniard might
+be, and yet his tongue seemed determined to get him into trouble in
+spite of all he could do. He made several efforts to creep out of his
+scrape, but the old man's eye was upon him and he made blunder after
+blunder. Presently the Welshman said:
+
+"My boy, don't be afraid of me. I wouldn't hurt a hair of your head
+for all the world. No--I'd protect you--I'd protect you. This Spaniard
+is not deaf and dumb; you've let that slip without intending it; you
+can't cover that up now. You know something about that Spaniard that
+you want to keep dark. Now trust me--tell me what it is, and trust me
+--I won't betray you."
+
+Huck looked into the old man's honest eyes a moment, then bent over
+and whispered in his ear:
+
+"'Tain't a Spaniard--it's Injun Joe!"
+
+The Welshman almost jumped out of his chair. In a moment he said:
+
+"It's all plain enough, now. When you talked about notching ears and
+slitting noses I judged that that was your own embellishment, because
+white men don't take that sort of revenge. But an Injun! That's a
+different matter altogether."
+
+During breakfast the talk went on, and in the course of it the old man
+said that the last thing which he and his sons had done, before going
+to bed, was to get a lantern and examine the stile and its vicinity for
+marks of blood. They found none, but captured a bulky bundle of--
+
+"Of WHAT?"
+
+If the words had been lightning they could not have leaped with a more
+stunning suddenness from Huck's blanched lips. His eyes were staring
+wide, now, and his breath suspended--waiting for the answer. The
+Welshman started--stared in return--three seconds--five seconds--ten
+--then replied:
+
+"Of burglar's tools. Why, what's the MATTER with you?"
+
+Huck sank back, panting gently, but deeply, unutterably grateful. The
+Welshman eyed him gravely, curiously--and presently said:
+
+"Yes, burglar's tools. That appears to relieve you a good deal. But
+what did give you that turn? What were YOU expecting we'd found?"
+
+Huck was in a close place--the inquiring eye was upon him--he would
+have given anything for material for a plausible answer--nothing
+suggested itself--the inquiring eye was boring deeper and deeper--a
+senseless reply offered--there was no time to weigh it, so at a venture
+he uttered it--feebly:
+
+"Sunday-school books, maybe."
+
+Poor Huck was too distressed to smile, but the old man laughed loud
+and joyously, shook up the details of his anatomy from head to foot,
+and ended by saying that such a laugh was money in a-man's pocket,
+because it cut down the doctor's bill like everything. Then he added:
+
+"Poor old chap, you're white and jaded--you ain't well a bit--no
+wonder you're a little flighty and off your balance. But you'll come
+out of it. Rest and sleep will fetch you out all right, I hope."
+
+Huck was irritated to think he had been such a goose and betrayed such
+a suspicious excitement, for he had dropped the idea that the parcel
+brought from the tavern was the treasure, as soon as he had heard the
+talk at the widow's stile. He had only thought it was not the treasure,
+however--he had not known that it wasn't--and so the suggestion of a
+captured bundle was too much for his self-possession. But on the whole
+he felt glad the little episode had happened, for now he knew beyond
+all question that that bundle was not THE bundle, and so his mind was
+at rest and exceedingly comfortable. In fact, everything seemed to be
+drifting just in the right direction, now; the treasure must be still
+in No. 2, the men would be captured and jailed that day, and he and Tom
+could seize the gold that night without any trouble or any fear of
+interruption.
+
+Just as breakfast was completed there was a knock at the door. Huck
+jumped for a hiding-place, for he had no mind to be connected even
+remotely with the late event. The Welshman admitted several ladies and
+gentlemen, among them the Widow Douglas, and noticed that groups of
+citizens were climbing up the hill--to stare at the stile. So the news
+had spread. The Welshman had to tell the story of the night to the
+visitors. The widow's gratitude for her preservation was outspoken.
+
+"Don't say a word about it, madam. There's another that you're more
+beholden to than you are to me and my boys, maybe, but he don't allow
+me to tell his name. We wouldn't have been there but for him."
+
+Of course this excited a curiosity so vast that it almost belittled
+the main matter--but the Welshman allowed it to eat into the vitals of
+his visitors, and through them be transmitted to the whole town, for he
+refused to part with his secret. When all else had been learned, the
+widow said:
+
+"I went to sleep reading in bed and slept straight through all that
+noise. Why didn't you come and wake me?"
+
+"We judged it warn't worth while. Those fellows warn't likely to come
+again--they hadn't any tools left to work with, and what was the use of
+waking you up and scaring you to death? My three negro men stood guard
+at your house all the rest of the night. They've just come back."
+
+More visitors came, and the story had to be told and retold for a
+couple of hours more.
+
+There was no Sabbath-school during day-school vacation, but everybody
+was early at church. The stirring event was well canvassed. News came
+that not a sign of the two villains had been yet discovered. When the
+sermon was finished, Judge Thatcher's wife dropped alongside of Mrs.
+Harper as she moved down the aisle with the crowd and said:
+
+"Is my Becky going to sleep all day? I just expected she would be
+tired to death."
+
+"Your Becky?"
+
+"Yes," with a startled look--"didn't she stay with you last night?"
+
+"Why, no."
+
+Mrs. Thatcher turned pale, and sank into a pew, just as Aunt Polly,
+talking briskly with a friend, passed by. Aunt Polly said:
+
+"Good-morning, Mrs. Thatcher. Good-morning, Mrs. Harper. I've got a
+boy that's turned up missing. I reckon my Tom stayed at your house last
+night--one of you. And now he's afraid to come to church. I've got to
+settle with him."
+
+Mrs. Thatcher shook her head feebly and turned paler than ever.
+
+"He didn't stay with us," said Mrs. Harper, beginning to look uneasy.
+A marked anxiety came into Aunt Polly's face.
+
+"Joe Harper, have you seen my Tom this morning?"
+
+"No'm."
+
+"When did you see him last?"
+
+Joe tried to remember, but was not sure he could say. The people had
+stopped moving out of church. Whispers passed along, and a boding
+uneasiness took possession of every countenance. Children were
+anxiously questioned, and young teachers. They all said they had not
+noticed whether Tom and Becky were on board the ferryboat on the
+homeward trip; it was dark; no one thought of inquiring if any one was
+missing. One young man finally blurted out his fear that they were
+still in the cave! Mrs. Thatcher swooned away. Aunt Polly fell to
+crying and wringing her hands.
+
+The alarm swept from lip to lip, from group to group, from street to
+street, and within five minutes the bells were wildly clanging and the
+whole town was up! The Cardiff Hill episode sank into instant
+insignificance, the burglars were forgotten, horses were saddled,
+skiffs were manned, the ferryboat ordered out, and before the horror
+was half an hour old, two hundred men were pouring down highroad and
+river toward the cave.
+
+All the long afternoon the village seemed empty and dead. Many women
+visited Aunt Polly and Mrs. Thatcher and tried to comfort them. They
+cried with them, too, and that was still better than words. All the
+tedious night the town waited for news; but when the morning dawned at
+last, all the word that came was, "Send more candles--and send food."
+Mrs. Thatcher was almost crazed; and Aunt Polly, also. Judge Thatcher
+sent messages of hope and encouragement from the cave, but they
+conveyed no real cheer.
+
+The old Welshman came home toward daylight, spattered with
+candle-grease, smeared with clay, and almost worn out. He found Huck
+still in the bed that had been provided for him, and delirious with
+fever. The physicians were all at the cave, so the Widow Douglas came
+and took charge of the patient. She said she would do her best by him,
+because, whether he was good, bad, or indifferent, he was the Lord's,
+and nothing that was the Lord's was a thing to be neglected. The
+Welshman said Huck had good spots in him, and the widow said:
+
+"You can depend on it. That's the Lord's mark. He don't leave it off.
+He never does. Puts it somewhere on every creature that comes from his
+hands."
+
+Early in the forenoon parties of jaded men began to straggle into the
+village, but the strongest of the citizens continued searching. All the
+news that could be gained was that remotenesses of the cavern were
+being ransacked that had never been visited before; that every corner
+and crevice was going to be thoroughly searched; that wherever one
+wandered through the maze of passages, lights were to be seen flitting
+hither and thither in the distance, and shoutings and pistol-shots sent
+their hollow reverberations to the ear down the sombre aisles. In one
+place, far from the section usually traversed by tourists, the names
+"BECKY & TOM" had been found traced upon the rocky wall with
+candle-smoke, and near at hand a grease-soiled bit of ribbon. Mrs.
+Thatcher recognized the ribbon and cried over it. She said it was the
+last relic she should ever have of her child; and that no other memorial
+of her could ever be so precious, because this one parted latest from
+the living body before the awful death came. Some said that now and
+then, in the cave, a far-away speck of light would glimmer, and then a
+glorious shout would burst forth and a score of men go trooping down the
+echoing aisle--and then a sickening disappointment always followed; the
+children were not there; it was only a searcher's light.
+
+Three dreadful days and nights dragged their tedious hours along, and
+the village sank into a hopeless stupor. No one had heart for anything.
+The accidental discovery, just made, that the proprietor of the
+Temperance Tavern kept liquor on his premises, scarcely fluttered the
+public pulse, tremendous as the fact was. In a lucid interval, Huck
+feebly led up to the subject of taverns, and finally asked--dimly
+dreading the worst--if anything had been discovered at the Temperance
+Tavern since he had been ill.
+
+"Yes," said the widow.
+
+Huck started up in bed, wild-eyed:
+
+"What? What was it?"
+
+"Liquor!--and the place has been shut up. Lie down, child--what a turn
+you did give me!"
+
+"Only tell me just one thing--only just one--please! Was it Tom Sawyer
+that found it?"
+
+The widow burst into tears. "Hush, hush, child, hush! I've told you
+before, you must NOT talk. You are very, very sick!"
+
+Then nothing but liquor had been found; there would have been a great
+powwow if it had been the gold. So the treasure was gone forever--gone
+forever! But what could she be crying about? Curious that she should
+cry.
+
+These thoughts worked their dim way through Huck's mind, and under the
+weariness they gave him he fell asleep. The widow said to herself:
+
+"There--he's asleep, poor wreck. Tom Sawyer find it! Pity but somebody
+could find Tom Sawyer! Ah, there ain't many left, now, that's got hope
+enough, or strength enough, either, to go on searching."
+
+
+
+CHAPTER XXXI
+
+NOW to return to Tom and Becky's share in the picnic. They tripped
+along the murky aisles with the rest of the company, visiting the
+familiar wonders of the cave--wonders dubbed with rather
+over-descriptive names, such as "The Drawing-Room," "The Cathedral,"
+"Aladdin's Palace," and so on. Presently the hide-and-seek frolicking
+began, and Tom and Becky engaged in it with zeal until the exertion
+began to grow a trifle wearisome; then they wandered down a sinuous
+avenue holding their candles aloft and reading the tangled web-work of
+names, dates, post-office addresses, and mottoes with which the rocky
+walls had been frescoed (in candle-smoke). Still drifting along and
+talking, they scarcely noticed that they were now in a part of the cave
+whose walls were not frescoed. They smoked their own names under an
+overhanging shelf and moved on. Presently they came to a place where a
+little stream of water, trickling over a ledge and carrying a limestone
+sediment with it, had, in the slow-dragging ages, formed a laced and
+ruffled Niagara in gleaming and imperishable stone. Tom squeezed his
+small body behind it in order to illuminate it for Becky's
+gratification. He found that it curtained a sort of steep natural
+stairway which was enclosed between narrow walls, and at once the
+ambition to be a discoverer seized him. Becky responded to his call,
+and they made a smoke-mark for future guidance, and started upon their
+quest. They wound this way and that, far down into the secret depths of
+the cave, made another mark, and branched off in search of novelties to
+tell the upper world about. In one place they found a spacious cavern,
+from whose ceiling depended a multitude of shining stalactites of the
+length and circumference of a man's leg; they walked all about it,
+wondering and admiring, and presently left it by one of the numerous
+passages that opened into it. This shortly brought them to a bewitching
+spring, whose basin was incrusted with a frostwork of glittering
+crystals; it was in the midst of a cavern whose walls were supported by
+many fantastic pillars which had been formed by the joining of great
+stalactites and stalagmites together, the result of the ceaseless
+water-drip of centuries. Under the roof vast knots of bats had packed
+themselves together, thousands in a bunch; the lights disturbed the
+creatures and they came flocking down by hundreds, squeaking and
+darting furiously at the candles. Tom knew their ways and the danger of
+this sort of conduct. He seized Becky's hand and hurried her into the
+first corridor that offered; and none too soon, for a bat struck
+Becky's light out with its wing while she was passing out of the
+cavern. The bats chased the children a good distance; but the fugitives
+plunged into every new passage that offered, and at last got rid of the
+perilous things. Tom found a subterranean lake, shortly, which
+stretched its dim length away until its shape was lost in the shadows.
+He wanted to explore its borders, but concluded that it would be best
+to sit down and rest awhile, first. Now, for the first time, the deep
+stillness of the place laid a clammy hand upon the spirits of the
+children. Becky said:
+
+"Why, I didn't notice, but it seems ever so long since I heard any of
+the others."
+
+"Come to think, Becky, we are away down below them--and I don't know
+how far away north, or south, or east, or whichever it is. We couldn't
+hear them here."
+
+Becky grew apprehensive.
+
+"I wonder how long we've been down here, Tom? We better start back."
+
+"Yes, I reckon we better. P'raps we better."
+
+"Can you find the way, Tom? It's all a mixed-up crookedness to me."
+
+"I reckon I could find it--but then the bats. If they put our candles
+out it will be an awful fix. Let's try some other way, so as not to go
+through there."
+
+"Well. But I hope we won't get lost. It would be so awful!" and the
+girl shuddered at the thought of the dreadful possibilities.
+
+They started through a corridor, and traversed it in silence a long
+way, glancing at each new opening, to see if there was anything
+familiar about the look of it; but they were all strange. Every time
+Tom made an examination, Becky would watch his face for an encouraging
+sign, and he would say cheerily:
+
+"Oh, it's all right. This ain't the one, but we'll come to it right
+away!"
+
+But he felt less and less hopeful with each failure, and presently
+began to turn off into diverging avenues at sheer random, in desperate
+hope of finding the one that was wanted. He still said it was "all
+right," but there was such a leaden dread at his heart that the words
+had lost their ring and sounded just as if he had said, "All is lost!"
+Becky clung to his side in an anguish of fear, and tried hard to keep
+back the tears, but they would come. At last she said:
+
+"Oh, Tom, never mind the bats, let's go back that way! We seem to get
+worse and worse off all the time."
+
+"Listen!" said he.
+
+Profound silence; silence so deep that even their breathings were
+conspicuous in the hush. Tom shouted. The call went echoing down the
+empty aisles and died out in the distance in a faint sound that
+resembled a ripple of mocking laughter.
+
+"Oh, don't do it again, Tom, it is too horrid," said Becky.
+
+"It is horrid, but I better, Becky; they might hear us, you know," and
+he shouted again.
+
+The "might" was even a chillier horror than the ghostly laughter, it
+so confessed a perishing hope. The children stood still and listened;
+but there was no result. Tom turned upon the back track at once, and
+hurried his steps. It was but a little while before a certain
+indecision in his manner revealed another fearful fact to Becky--he
+could not find his way back!
+
+"Oh, Tom, you didn't make any marks!"
+
+"Becky, I was such a fool! Such a fool! I never thought we might want
+to come back! No--I can't find the way. It's all mixed up."
+
+"Tom, Tom, we're lost! we're lost! We never can get out of this awful
+place! Oh, why DID we ever leave the others!"
+
+She sank to the ground and burst into such a frenzy of crying that Tom
+was appalled with the idea that she might die, or lose her reason. He
+sat down by her and put his arms around her; she buried her face in his
+bosom, she clung to him, she poured out her terrors, her unavailing
+regrets, and the far echoes turned them all to jeering laughter. Tom
+begged her to pluck up hope again, and she said she could not. He fell
+to blaming and abusing himself for getting her into this miserable
+situation; this had a better effect. She said she would try to hope
+again, she would get up and follow wherever he might lead if only he
+would not talk like that any more. For he was no more to blame than
+she, she said.
+
+So they moved on again--aimlessly--simply at random--all they could do
+was to move, keep moving. For a little while, hope made a show of
+reviving--not with any reason to back it, but only because it is its
+nature to revive when the spring has not been taken out of it by age
+and familiarity with failure.
+
+By-and-by Tom took Becky's candle and blew it out. This economy meant
+so much! Words were not needed. Becky understood, and her hope died
+again. She knew that Tom had a whole candle and three or four pieces in
+his pockets--yet he must economize.
+
+By-and-by, fatigue began to assert its claims; the children tried to
+pay attention, for it was dreadful to think of sitting down when time
+was grown to be so precious, moving, in some direction, in any
+direction, was at least progress and might bear fruit; but to sit down
+was to invite death and shorten its pursuit.
+
+At last Becky's frail limbs refused to carry her farther. She sat
+down. Tom rested with her, and they talked of home, and the friends
+there, and the comfortable beds and, above all, the light! Becky cried,
+and Tom tried to think of some way of comforting her, but all his
+encouragements were grown threadbare with use, and sounded like
+sarcasms. Fatigue bore so heavily upon Becky that she drowsed off to
+sleep. Tom was grateful. He sat looking into her drawn face and saw it
+grow smooth and natural under the influence of pleasant dreams; and
+by-and-by a smile dawned and rested there. The peaceful face reflected
+somewhat of peace and healing into his own spirit, and his thoughts
+wandered away to bygone times and dreamy memories. While he was deep in
+his musings, Becky woke up with a breezy little laugh--but it was
+stricken dead upon her lips, and a groan followed it.
+
+"Oh, how COULD I sleep! I wish I never, never had waked! No! No, I
+don't, Tom! Don't look so! I won't say it again."
+
+"I'm glad you've slept, Becky; you'll feel rested, now, and we'll find
+the way out."
+
+"We can try, Tom; but I've seen such a beautiful country in my dream.
+I reckon we are going there."
+
+"Maybe not, maybe not. Cheer up, Becky, and let's go on trying."
+
+They rose up and wandered along, hand in hand and hopeless. They tried
+to estimate how long they had been in the cave, but all they knew was
+that it seemed days and weeks, and yet it was plain that this could not
+be, for their candles were not gone yet. A long time after this--they
+could not tell how long--Tom said they must go softly and listen for
+dripping water--they must find a spring. They found one presently, and
+Tom said it was time to rest again. Both were cruelly tired, yet Becky
+said she thought she could go a little farther. She was surprised to
+hear Tom dissent. She could not understand it. They sat down, and Tom
+fastened his candle to the wall in front of them with some clay.
+Thought was soon busy; nothing was said for some time. Then Becky broke
+the silence:
+
+"Tom, I am so hungry!"
+
+Tom took something out of his pocket.
+
+"Do you remember this?" said he.
+
+Becky almost smiled.
+
+"It's our wedding-cake, Tom."
+
+"Yes--I wish it was as big as a barrel, for it's all we've got."
+
+"I saved it from the picnic for us to dream on, Tom, the way grown-up
+people do with wedding-cake--but it'll be our--"
+
+She dropped the sentence where it was. Tom divided the cake and Becky
+ate with good appetite, while Tom nibbled at his moiety. There was
+abundance of cold water to finish the feast with. By-and-by Becky
+suggested that they move on again. Tom was silent a moment. Then he
+said:
+
+"Becky, can you bear it if I tell you something?"
+
+Becky's face paled, but she thought she could.
+
+"Well, then, Becky, we must stay here, where there's water to drink.
+That little piece is our last candle!"
+
+Becky gave loose to tears and wailings. Tom did what he could to
+comfort her, but with little effect. At length Becky said:
+
+"Tom!"
+
+"Well, Becky?"
+
+"They'll miss us and hunt for us!"
+
+"Yes, they will! Certainly they will!"
+
+"Maybe they're hunting for us now, Tom."
+
+"Why, I reckon maybe they are. I hope they are."
+
+"When would they miss us, Tom?"
+
+"When they get back to the boat, I reckon."
+
+"Tom, it might be dark then--would they notice we hadn't come?"
+
+"I don't know. But anyway, your mother would miss you as soon as they
+got home."
+
+A frightened look in Becky's face brought Tom to his senses and he saw
+that he had made a blunder. Becky was not to have gone home that night!
+The children became silent and thoughtful. In a moment a new burst of
+grief from Becky showed Tom that the thing in his mind had struck hers
+also--that the Sabbath morning might be half spent before Mrs. Thatcher
+discovered that Becky was not at Mrs. Harper's.
+
+The children fastened their eyes upon their bit of candle and watched
+it melt slowly and pitilessly away; saw the half inch of wick stand
+alone at last; saw the feeble flame rise and fall, climb the thin
+column of smoke, linger at its top a moment, and then--the horror of
+utter darkness reigned!
+
+How long afterward it was that Becky came to a slow consciousness that
+she was crying in Tom's arms, neither could tell. All that they knew
+was, that after what seemed a mighty stretch of time, both awoke out of
+a dead stupor of sleep and resumed their miseries once more. Tom said
+it might be Sunday, now--maybe Monday. He tried to get Becky to talk,
+but her sorrows were too oppressive, all her hopes were gone. Tom said
+that they must have been missed long ago, and no doubt the search was
+going on. He would shout and maybe some one would come. He tried it;
+but in the darkness the distant echoes sounded so hideously that he
+tried it no more.
+
+The hours wasted away, and hunger came to torment the captives again.
+A portion of Tom's half of the cake was left; they divided and ate it.
+But they seemed hungrier than before. The poor morsel of food only
+whetted desire.
+
+By-and-by Tom said:
+
+"SH! Did you hear that?"
+
+Both held their breath and listened. There was a sound like the
+faintest, far-off shout. Instantly Tom answered it, and leading Becky
+by the hand, started groping down the corridor in its direction.
+Presently he listened again; again the sound was heard, and apparently
+a little nearer.
+
+"It's them!" said Tom; "they're coming! Come along, Becky--we're all
+right now!"
+
+The joy of the prisoners was almost overwhelming. Their speed was
+slow, however, because pitfalls were somewhat common, and had to be
+guarded against. They shortly came to one and had to stop. It might be
+three feet deep, it might be a hundred--there was no passing it at any
+rate. Tom got down on his breast and reached as far down as he could.
+No bottom. They must stay there and wait until the searchers came. They
+listened; evidently the distant shoutings were growing more distant! a
+moment or two more and they had gone altogether. The heart-sinking
+misery of it! Tom whooped until he was hoarse, but it was of no use. He
+talked hopefully to Becky; but an age of anxious waiting passed and no
+sounds came again.
+
+The children groped their way back to the spring. The weary time
+dragged on; they slept again, and awoke famished and woe-stricken. Tom
+believed it must be Tuesday by this time.
+
+Now an idea struck him. There were some side passages near at hand. It
+would be better to explore some of these than bear the weight of the
+heavy time in idleness. He took a kite-line from his pocket, tied it to
+a projection, and he and Becky started, Tom in the lead, unwinding the
+line as he groped along. At the end of twenty steps the corridor ended
+in a "jumping-off place." Tom got down on his knees and felt below, and
+then as far around the corner as he could reach with his hands
+conveniently; he made an effort to stretch yet a little farther to the
+right, and at that moment, not twenty yards away, a human hand, holding
+a candle, appeared from behind a rock! Tom lifted up a glorious shout,
+and instantly that hand was followed by the body it belonged to--Injun
+Joe's! Tom was paralyzed; he could not move. He was vastly gratified
+the next moment, to see the "Spaniard" take to his heels and get
+himself out of sight. Tom wondered that Joe had not recognized his
+voice and come over and killed him for testifying in court. But the
+echoes must have disguised the voice. Without doubt, that was it, he
+reasoned. Tom's fright weakened every muscle in his body. He said to
+himself that if he had strength enough to get back to the spring he
+would stay there, and nothing should tempt him to run the risk of
+meeting Injun Joe again. He was careful to keep from Becky what it was
+he had seen. He told her he had only shouted "for luck."
+
+But hunger and wretchedness rise superior to fears in the long run.
+Another tedious wait at the spring and another long sleep brought
+changes. The children awoke tortured with a raging hunger. Tom believed
+that it must be Wednesday or Thursday or even Friday or Saturday, now,
+and that the search had been given over. He proposed to explore another
+passage. He felt willing to risk Injun Joe and all other terrors. But
+Becky was very weak. She had sunk into a dreary apathy and would not be
+roused. She said she would wait, now, where she was, and die--it would
+not be long. She told Tom to go with the kite-line and explore if he
+chose; but she implored him to come back every little while and speak
+to her; and she made him promise that when the awful time came, he
+would stay by her and hold her hand until all was over.
+
+Tom kissed her, with a choking sensation in his throat, and made a
+show of being confident of finding the searchers or an escape from the
+cave; then he took the kite-line in his hand and went groping down one
+of the passages on his hands and knees, distressed with hunger and sick
+with bodings of coming doom.
+
+
+
+CHAPTER XXXII
+
+TUESDAY afternoon came, and waned to the twilight. The village of St.
+Petersburg still mourned. The lost children had not been found. Public
+prayers had been offered up for them, and many and many a private
+prayer that had the petitioner's whole heart in it; but still no good
+news came from the cave. The majority of the searchers had given up the
+quest and gone back to their daily avocations, saying that it was plain
+the children could never be found. Mrs. Thatcher was very ill, and a
+great part of the time delirious. People said it was heartbreaking to
+hear her call her child, and raise her head and listen a whole minute
+at a time, then lay it wearily down again with a moan. Aunt Polly had
+drooped into a settled melancholy, and her gray hair had grown almost
+white. The village went to its rest on Tuesday night, sad and forlorn.
+
+Away in the middle of the night a wild peal burst from the village
+bells, and in a moment the streets were swarming with frantic half-clad
+people, who shouted, "Turn out! turn out! they're found! they're
+found!" Tin pans and horns were added to the din, the population massed
+itself and moved toward the river, met the children coming in an open
+carriage drawn by shouting citizens, thronged around it, joined its
+homeward march, and swept magnificently up the main street roaring
+huzzah after huzzah!
+
+The village was illuminated; nobody went to bed again; it was the
+greatest night the little town had ever seen. During the first half-hour
+a procession of villagers filed through Judge Thatcher's house, seized
+the saved ones and kissed them, squeezed Mrs. Thatcher's hand, tried to
+speak but couldn't--and drifted out raining tears all over the place.
+
+Aunt Polly's happiness was complete, and Mrs. Thatcher's nearly so. It
+would be complete, however, as soon as the messenger dispatched with
+the great news to the cave should get the word to her husband. Tom lay
+upon a sofa with an eager auditory about him and told the history of
+the wonderful adventure, putting in many striking additions to adorn it
+withal; and closed with a description of how he left Becky and went on
+an exploring expedition; how he followed two avenues as far as his
+kite-line would reach; how he followed a third to the fullest stretch of
+the kite-line, and was about to turn back when he glimpsed a far-off
+speck that looked like daylight; dropped the line and groped toward it,
+pushed his head and shoulders through a small hole, and saw the broad
+Mississippi rolling by! And if it had only happened to be night he would
+not have seen that speck of daylight and would not have explored that
+passage any more! He told how he went back for Becky and broke the good
+news and she told him not to fret her with such stuff, for she was
+tired, and knew she was going to die, and wanted to. He described how he
+labored with her and convinced her; and how she almost died for joy when
+she had groped to where she actually saw the blue speck of daylight; how
+he pushed his way out at the hole and then helped her out; how they sat
+there and cried for gladness; how some men came along in a skiff and Tom
+hailed them and told them their situation and their famished condition;
+how the men didn't believe the wild tale at first, "because," said they,
+"you are five miles down the river below the valley the cave is in"
+--then took them aboard, rowed to a house, gave them supper, made them
+rest till two or three hours after dark and then brought them home.
+
+Before day-dawn, Judge Thatcher and the handful of searchers with him
+were tracked out, in the cave, by the twine clews they had strung
+behind them, and informed of the great news.
+
+Three days and nights of toil and hunger in the cave were not to be
+shaken off at once, as Tom and Becky soon discovered. They were
+bedridden all of Wednesday and Thursday, and seemed to grow more and
+more tired and worn, all the time. Tom got about, a little, on
+Thursday, was down-town Friday, and nearly as whole as ever Saturday;
+but Becky did not leave her room until Sunday, and then she looked as
+if she had passed through a wasting illness.
+
+Tom learned of Huck's sickness and went to see him on Friday, but
+could not be admitted to the bedroom; neither could he on Saturday or
+Sunday. He was admitted daily after that, but was warned to keep still
+about his adventure and introduce no exciting topic. The Widow Douglas
+stayed by to see that he obeyed. At home Tom learned of the Cardiff
+Hill event; also that the "ragged man's" body had eventually been found
+in the river near the ferry-landing; he had been drowned while trying
+to escape, perhaps.
+
+About a fortnight after Tom's rescue from the cave, he started off to
+visit Huck, who had grown plenty strong enough, now, to hear exciting
+talk, and Tom had some that would interest him, he thought. Judge
+Thatcher's house was on Tom's way, and he stopped to see Becky. The
+Judge and some friends set Tom to talking, and some one asked him
+ironically if he wouldn't like to go to the cave again. Tom said he
+thought he wouldn't mind it. The Judge said:
+
+"Well, there are others just like you, Tom, I've not the least doubt.
+But we have taken care of that. Nobody will get lost in that cave any
+more."
+
+"Why?"
+
+"Because I had its big door sheathed with boiler iron two weeks ago,
+and triple-locked--and I've got the keys."
+
+Tom turned as white as a sheet.
+
+"What's the matter, boy! Here, run, somebody! Fetch a glass of water!"
+
+The water was brought and thrown into Tom's face.
+
+"Ah, now you're all right. What was the matter with you, Tom?"
+
+"Oh, Judge, Injun Joe's in the cave!"
+
+
+
+CHAPTER XXXIII
+
+WITHIN a few minutes the news had spread, and a dozen skiff-loads of
+men were on their way to McDougal's cave, and the ferryboat, well
+filled with passengers, soon followed. Tom Sawyer was in the skiff that
+bore Judge Thatcher.
+
+When the cave door was unlocked, a sorrowful sight presented itself in
+the dim twilight of the place. Injun Joe lay stretched upon the ground,
+dead, with his face close to the crack of the door, as if his longing
+eyes had been fixed, to the latest moment, upon the light and the cheer
+of the free world outside. Tom was touched, for he knew by his own
+experience how this wretch had suffered. His pity was moved, but
+nevertheless he felt an abounding sense of relief and security, now,
+which revealed to him in a degree which he had not fully appreciated
+before how vast a weight of dread had been lying upon him since the day
+he lifted his voice against this bloody-minded outcast.
+
+Injun Joe's bowie-knife lay close by, its blade broken in two. The
+great foundation-beam of the door had been chipped and hacked through,
+with tedious labor; useless labor, too, it was, for the native rock
+formed a sill outside it, and upon that stubborn material the knife had
+wrought no effect; the only damage done was to the knife itself. But if
+there had been no stony obstruction there the labor would have been
+useless still, for if the beam had been wholly cut away Injun Joe could
+not have squeezed his body under the door, and he knew it. So he had
+only hacked that place in order to be doing something--in order to pass
+the weary time--in order to employ his tortured faculties. Ordinarily
+one could find half a dozen bits of candle stuck around in the crevices
+of this vestibule, left there by tourists; but there were none now. The
+prisoner had searched them out and eaten them. He had also contrived to
+catch a few bats, and these, also, he had eaten, leaving only their
+claws. The poor unfortunate had starved to death. In one place, near at
+hand, a stalagmite had been slowly growing up from the ground for ages,
+builded by the water-drip from a stalactite overhead. The captive had
+broken off the stalagmite, and upon the stump had placed a stone,
+wherein he had scooped a shallow hollow to catch the precious drop
+that fell once in every three minutes with the dreary regularity of a
+clock-tick--a dessertspoonful once in four and twenty hours. That drop
+was falling when the Pyramids were new; when Troy fell; when the
+foundations of Rome were laid; when Christ was crucified; when the
+Conqueror created the British empire; when Columbus sailed; when the
+massacre at Lexington was "news." It is falling now; it will still be
+falling when all these things shall have sunk down the afternoon of
+history, and the twilight of tradition, and been swallowed up in the
+thick night of oblivion. Has everything a purpose and a mission? Did
+this drop fall patiently during five thousand years to be ready for
+this flitting human insect's need? and has it another important object
+to accomplish ten thousand years to come? No matter. It is many and
+many a year since the hapless half-breed scooped out the stone to catch
+the priceless drops, but to this day the tourist stares longest at that
+pathetic stone and that slow-dropping water when he comes to see the
+wonders of McDougal's cave. Injun Joe's cup stands first in the list of
+the cavern's marvels; even "Aladdin's Palace" cannot rival it.
+
+Injun Joe was buried near the mouth of the cave; and people flocked
+there in boats and wagons from the towns and from all the farms and
+hamlets for seven miles around; they brought their children, and all
+sorts of provisions, and confessed that they had had almost as
+satisfactory a time at the funeral as they could have had at the
+hanging.
+
+This funeral stopped the further growth of one thing--the petition to
+the governor for Injun Joe's pardon. The petition had been largely
+signed; many tearful and eloquent meetings had been held, and a
+committee of sappy women been appointed to go in deep mourning and wail
+around the governor, and implore him to be a merciful ass and trample
+his duty under foot. Injun Joe was believed to have killed five
+citizens of the village, but what of that? If he had been Satan himself
+there would have been plenty of weaklings ready to scribble their names
+to a pardon-petition, and drip a tear on it from their permanently
+impaired and leaky water-works.
+
+The morning after the funeral Tom took Huck to a private place to have
+an important talk. Huck had learned all about Tom's adventure from the
+Welshman and the Widow Douglas, by this time, but Tom said he reckoned
+there was one thing they had not told him; that thing was what he
+wanted to talk about now. Huck's face saddened. He said:
+
+"I know what it is. You got into No. 2 and never found anything but
+whiskey. Nobody told me it was you; but I just knowed it must 'a' ben
+you, soon as I heard 'bout that whiskey business; and I knowed you
+hadn't got the money becuz you'd 'a' got at me some way or other and
+told me even if you was mum to everybody else. Tom, something's always
+told me we'd never get holt of that swag."
+
+"Why, Huck, I never told on that tavern-keeper. YOU know his tavern
+was all right the Saturday I went to the picnic. Don't you remember you
+was to watch there that night?"
+
+"Oh yes! Why, it seems 'bout a year ago. It was that very night that I
+follered Injun Joe to the widder's."
+
+"YOU followed him?"
+
+"Yes--but you keep mum. I reckon Injun Joe's left friends behind him,
+and I don't want 'em souring on me and doing me mean tricks. If it
+hadn't ben for me he'd be down in Texas now, all right."
+
+Then Huck told his entire adventure in confidence to Tom, who had only
+heard of the Welshman's part of it before.
+
+"Well," said Huck, presently, coming back to the main question,
+"whoever nipped the whiskey in No. 2, nipped the money, too, I reckon
+--anyways it's a goner for us, Tom."
+
+"Huck, that money wasn't ever in No. 2!"
+
+"What!" Huck searched his comrade's face keenly. "Tom, have you got on
+the track of that money again?"
+
+"Huck, it's in the cave!"
+
+Huck's eyes blazed.
+
+"Say it again, Tom."
+
+"The money's in the cave!"
+
+"Tom--honest injun, now--is it fun, or earnest?"
+
+"Earnest, Huck--just as earnest as ever I was in my life. Will you go
+in there with me and help get it out?"
+
+"I bet I will! I will if it's where we can blaze our way to it and not
+get lost."
+
+"Huck, we can do that without the least little bit of trouble in the
+world."
+
+"Good as wheat! What makes you think the money's--"
+
+"Huck, you just wait till we get in there. If we don't find it I'll
+agree to give you my drum and every thing I've got in the world. I
+will, by jings."
+
+"All right--it's a whiz. When do you say?"
+
+"Right now, if you say it. Are you strong enough?"
+
+"Is it far in the cave? I ben on my pins a little, three or four days,
+now, but I can't walk more'n a mile, Tom--least I don't think I could."
+
+"It's about five mile into there the way anybody but me would go,
+Huck, but there's a mighty short cut that they don't anybody but me
+know about. Huck, I'll take you right to it in a skiff. I'll float the
+skiff down there, and I'll pull it back again all by myself. You
+needn't ever turn your hand over."
+
+"Less start right off, Tom."
+
+"All right. We want some bread and meat, and our pipes, and a little
+bag or two, and two or three kite-strings, and some of these
+new-fangled things they call lucifer matches. I tell you, many's
+the time I wished I had some when I was in there before."
+
+A trifle after noon the boys borrowed a small skiff from a citizen who
+was absent, and got under way at once. When they were several miles
+below "Cave Hollow," Tom said:
+
+"Now you see this bluff here looks all alike all the way down from the
+cave hollow--no houses, no wood-yards, bushes all alike. But do you see
+that white place up yonder where there's been a landslide? Well, that's
+one of my marks. We'll get ashore, now."
+
+They landed.
+
+"Now, Huck, where we're a-standing you could touch that hole I got out
+of with a fishing-pole. See if you can find it."
+
+Huck searched all the place about, and found nothing. Tom proudly
+marched into a thick clump of sumach bushes and said:
+
+"Here you are! Look at it, Huck; it's the snuggest hole in this
+country. You just keep mum about it. All along I've been wanting to be
+a robber, but I knew I'd got to have a thing like this, and where to
+run across it was the bother. We've got it now, and we'll keep it
+quiet, only we'll let Joe Harper and Ben Rogers in--because of course
+there's got to be a Gang, or else there wouldn't be any style about it.
+Tom Sawyer's Gang--it sounds splendid, don't it, Huck?"
+
+"Well, it just does, Tom. And who'll we rob?"
+
+"Oh, most anybody. Waylay people--that's mostly the way."
+
+"And kill them?"
+
+"No, not always. Hive them in the cave till they raise a ransom."
+
+"What's a ransom?"
+
+"Money. You make them raise all they can, off'n their friends; and
+after you've kept them a year, if it ain't raised then you kill them.
+That's the general way. Only you don't kill the women. You shut up the
+women, but you don't kill them. They're always beautiful and rich, and
+awfully scared. You take their watches and things, but you always take
+your hat off and talk polite. They ain't anybody as polite as robbers
+--you'll see that in any book. Well, the women get to loving you, and
+after they've been in the cave a week or two weeks they stop crying and
+after that you couldn't get them to leave. If you drove them out they'd
+turn right around and come back. It's so in all the books."
+
+"Why, it's real bully, Tom. I believe it's better'n to be a pirate."
+
+"Yes, it's better in some ways, because it's close to home and
+circuses and all that."
+
+By this time everything was ready and the boys entered the hole, Tom
+in the lead. They toiled their way to the farther end of the tunnel,
+then made their spliced kite-strings fast and moved on. A few steps
+brought them to the spring, and Tom felt a shudder quiver all through
+him. He showed Huck the fragment of candle-wick perched on a lump of
+clay against the wall, and described how he and Becky had watched the
+flame struggle and expire.
+
+The boys began to quiet down to whispers, now, for the stillness and
+gloom of the place oppressed their spirits. They went on, and presently
+entered and followed Tom's other corridor until they reached the
+"jumping-off place." The candles revealed the fact that it was not
+really a precipice, but only a steep clay hill twenty or thirty feet
+high. Tom whispered:
+
+"Now I'll show you something, Huck."
+
+He held his candle aloft and said:
+
+"Look as far around the corner as you can. Do you see that? There--on
+the big rock over yonder--done with candle-smoke."
+
+"Tom, it's a CROSS!"
+
+"NOW where's your Number Two? 'UNDER THE CROSS,' hey? Right yonder's
+where I saw Injun Joe poke up his candle, Huck!"
+
+Huck stared at the mystic sign awhile, and then said with a shaky voice:
+
+"Tom, less git out of here!"
+
+"What! and leave the treasure?"
+
+"Yes--leave it. Injun Joe's ghost is round about there, certain."
+
+"No it ain't, Huck, no it ain't. It would ha'nt the place where he
+died--away out at the mouth of the cave--five mile from here."
+
+"No, Tom, it wouldn't. It would hang round the money. I know the ways
+of ghosts, and so do you."
+
+Tom began to fear that Huck was right. Misgivings gathered in his
+mind. But presently an idea occurred to him--
+
+"Lookyhere, Huck, what fools we're making of ourselves! Injun Joe's
+ghost ain't a going to come around where there's a cross!"
+
+The point was well taken. It had its effect.
+
+"Tom, I didn't think of that. But that's so. It's luck for us, that
+cross is. I reckon we'll climb down there and have a hunt for that box."
+
+Tom went first, cutting rude steps in the clay hill as he descended.
+Huck followed. Four avenues opened out of the small cavern which the
+great rock stood in. The boys examined three of them with no result.
+They found a small recess in the one nearest the base of the rock, with
+a pallet of blankets spread down in it; also an old suspender, some
+bacon rind, and the well-gnawed bones of two or three fowls. But there
+was no money-box. The lads searched and researched this place, but in
+vain. Tom said:
+
+"He said UNDER the cross. Well, this comes nearest to being under the
+cross. It can't be under the rock itself, because that sets solid on
+the ground."
+
+They searched everywhere once more, and then sat down discouraged.
+Huck could suggest nothing. By-and-by Tom said:
+
+"Lookyhere, Huck, there's footprints and some candle-grease on the
+clay about one side of this rock, but not on the other sides. Now,
+what's that for? I bet you the money IS under the rock. I'm going to
+dig in the clay."
+
+"That ain't no bad notion, Tom!" said Huck with animation.
+
+Tom's "real Barlow" was out at once, and he had not dug four inches
+before he struck wood.
+
+"Hey, Huck!--you hear that?"
+
+Huck began to dig and scratch now. Some boards were soon uncovered and
+removed. They had concealed a natural chasm which led under the rock.
+Tom got into this and held his candle as far under the rock as he
+could, but said he could not see to the end of the rift. He proposed to
+explore. He stooped and passed under; the narrow way descended
+gradually. He followed its winding course, first to the right, then to
+the left, Huck at his heels. Tom turned a short curve, by-and-by, and
+exclaimed:
+
+"My goodness, Huck, lookyhere!"
+
+It was the treasure-box, sure enough, occupying a snug little cavern,
+along with an empty powder-keg, a couple of guns in leather cases, two
+or three pairs of old moccasins, a leather belt, and some other rubbish
+well soaked with the water-drip.
+
+"Got it at last!" said Huck, ploughing among the tarnished coins with
+his hand. "My, but we're rich, Tom!"
+
+"Huck, I always reckoned we'd get it. It's just too good to believe,
+but we HAVE got it, sure! Say--let's not fool around here. Let's snake
+it out. Lemme see if I can lift the box."
+
+It weighed about fifty pounds. Tom could lift it, after an awkward
+fashion, but could not carry it conveniently.
+
+"I thought so," he said; "THEY carried it like it was heavy, that day
+at the ha'nted house. I noticed that. I reckon I was right to think of
+fetching the little bags along."
+
+The money was soon in the bags and the boys took it up to the cross
+rock.
+
+"Now less fetch the guns and things," said Huck.
+
+"No, Huck--leave them there. They're just the tricks to have when we
+go to robbing. We'll keep them there all the time, and we'll hold our
+orgies there, too. It's an awful snug place for orgies."
+
+"What orgies?"
+
+"I dono. But robbers always have orgies, and of course we've got to
+have them, too. Come along, Huck, we've been in here a long time. It's
+getting late, I reckon. I'm hungry, too. We'll eat and smoke when we
+get to the skiff."
+
+They presently emerged into the clump of sumach bushes, looked warily
+out, found the coast clear, and were soon lunching and smoking in the
+skiff. As the sun dipped toward the horizon they pushed out and got
+under way. Tom skimmed up the shore through the long twilight, chatting
+cheerily with Huck, and landed shortly after dark.
+
+"Now, Huck," said Tom, "we'll hide the money in the loft of the
+widow's woodshed, and I'll come up in the morning and we'll count it
+and divide, and then we'll hunt up a place out in the woods for it
+where it will be safe. Just you lay quiet here and watch the stuff till
+I run and hook Benny Taylor's little wagon; I won't be gone a minute."
+
+He disappeared, and presently returned with the wagon, put the two
+small sacks into it, threw some old rags on top of them, and started
+off, dragging his cargo behind him. When the boys reached the
+Welshman's house, they stopped to rest. Just as they were about to move
+on, the Welshman stepped out and said:
+
+"Hallo, who's that?"
+
+"Huck and Tom Sawyer."
+
+"Good! Come along with me, boys, you are keeping everybody waiting.
+Here--hurry up, trot ahead--I'll haul the wagon for you. Why, it's not
+as light as it might be. Got bricks in it?--or old metal?"
+
+"Old metal," said Tom.
+
+"I judged so; the boys in this town will take more trouble and fool
+away more time hunting up six bits' worth of old iron to sell to the
+foundry than they would to make twice the money at regular work. But
+that's human nature--hurry along, hurry along!"
+
+The boys wanted to know what the hurry was about.
+
+"Never mind; you'll see, when we get to the Widow Douglas'."
+
+Huck said with some apprehension--for he was long used to being
+falsely accused:
+
+"Mr. Jones, we haven't been doing nothing."
+
+The Welshman laughed.
+
+"Well, I don't know, Huck, my boy. I don't know about that. Ain't you
+and the widow good friends?"
+
+"Yes. Well, she's ben good friends to me, anyway."
+
+"All right, then. What do you want to be afraid for?"
+
+This question was not entirely answered in Huck's slow mind before he
+found himself pushed, along with Tom, into Mrs. Douglas' drawing-room.
+Mr. Jones left the wagon near the door and followed.
+
+The place was grandly lighted, and everybody that was of any
+consequence in the village was there. The Thatchers were there, the
+Harpers, the Rogerses, Aunt Polly, Sid, Mary, the minister, the editor,
+and a great many more, and all dressed in their best. The widow
+received the boys as heartily as any one could well receive two such
+looking beings. They were covered with clay and candle-grease. Aunt
+Polly blushed crimson with humiliation, and frowned and shook her head
+at Tom. Nobody suffered half as much as the two boys did, however. Mr.
+Jones said:
+
+"Tom wasn't at home, yet, so I gave him up; but I stumbled on him and
+Huck right at my door, and so I just brought them along in a hurry."
+
+"And you did just right," said the widow. "Come with me, boys."
+
+She took them to a bedchamber and said:
+
+"Now wash and dress yourselves. Here are two new suits of clothes
+--shirts, socks, everything complete. They're Huck's--no, no thanks,
+Huck--Mr. Jones bought one and I the other. But they'll fit both of you.
+Get into them. We'll wait--come down when you are slicked up enough."
+
+Then she left.
+
+
+
+CHAPTER XXXIV
+
+HUCK said: "Tom, we can slope, if we can find a rope. The window ain't
+high from the ground."
+
+"Shucks! what do you want to slope for?"
+
+"Well, I ain't used to that kind of a crowd. I can't stand it. I ain't
+going down there, Tom."
+
+"Oh, bother! It ain't anything. I don't mind it a bit. I'll take care
+of you."
+
+Sid appeared.
+
+"Tom," said he, "auntie has been waiting for you all the afternoon.
+Mary got your Sunday clothes ready, and everybody's been fretting about
+you. Say--ain't this grease and clay, on your clothes?"
+
+"Now, Mr. Siddy, you jist 'tend to your own business. What's all this
+blow-out about, anyway?"
+
+"It's one of the widow's parties that she's always having. This time
+it's for the Welshman and his sons, on account of that scrape they
+helped her out of the other night. And say--I can tell you something,
+if you want to know."
+
+"Well, what?"
+
+"Why, old Mr. Jones is going to try to spring something on the people
+here to-night, but I overheard him tell auntie to-day about it, as a
+secret, but I reckon it's not much of a secret now. Everybody knows
+--the widow, too, for all she tries to let on she don't. Mr. Jones was
+bound Huck should be here--couldn't get along with his grand secret
+without Huck, you know!"
+
+"Secret about what, Sid?"
+
+"About Huck tracking the robbers to the widow's. I reckon Mr. Jones
+was going to make a grand time over his surprise, but I bet you it will
+drop pretty flat."
+
+Sid chuckled in a very contented and satisfied way.
+
+"Sid, was it you that told?"
+
+"Oh, never mind who it was. SOMEBODY told--that's enough."
+
+"Sid, there's only one person in this town mean enough to do that, and
+that's you. If you had been in Huck's place you'd 'a' sneaked down the
+hill and never told anybody on the robbers. You can't do any but mean
+things, and you can't bear to see anybody praised for doing good ones.
+There--no thanks, as the widow says"--and Tom cuffed Sid's ears and
+helped him to the door with several kicks. "Now go and tell auntie if
+you dare--and to-morrow you'll catch it!"
+
+Some minutes later the widow's guests were at the supper-table, and a
+dozen children were propped up at little side-tables in the same room,
+after the fashion of that country and that day. At the proper time Mr.
+Jones made his little speech, in which he thanked the widow for the
+honor she was doing himself and his sons, but said that there was
+another person whose modesty--
+
+And so forth and so on. He sprung his secret about Huck's share in the
+adventure in the finest dramatic manner he was master of, but the
+surprise it occasioned was largely counterfeit and not as clamorous and
+effusive as it might have been under happier circumstances. However,
+the widow made a pretty fair show of astonishment, and heaped so many
+compliments and so much gratitude upon Huck that he almost forgot the
+nearly intolerable discomfort of his new clothes in the entirely
+intolerable discomfort of being set up as a target for everybody's gaze
+and everybody's laudations.
+
+The widow said she meant to give Huck a home under her roof and have
+him educated; and that when she could spare the money she would start
+him in business in a modest way. Tom's chance was come. He said:
+
+"Huck don't need it. Huck's rich."
+
+Nothing but a heavy strain upon the good manners of the company kept
+back the due and proper complimentary laugh at this pleasant joke. But
+the silence was a little awkward. Tom broke it:
+
+"Huck's got money. Maybe you don't believe it, but he's got lots of
+it. Oh, you needn't smile--I reckon I can show you. You just wait a
+minute."
+
+Tom ran out of doors. The company looked at each other with a
+perplexed interest--and inquiringly at Huck, who was tongue-tied.
+
+"Sid, what ails Tom?" said Aunt Polly. "He--well, there ain't ever any
+making of that boy out. I never--"
+
+Tom entered, struggling with the weight of his sacks, and Aunt Polly
+did not finish her sentence. Tom poured the mass of yellow coin upon
+the table and said:
+
+"There--what did I tell you? Half of it's Huck's and half of it's mine!"
+
+The spectacle took the general breath away. All gazed, nobody spoke
+for a moment. Then there was a unanimous call for an explanation. Tom
+said he could furnish it, and he did. The tale was long, but brimful of
+interest. There was scarcely an interruption from any one to break the
+charm of its flow. When he had finished, Mr. Jones said:
+
+"I thought I had fixed up a little surprise for this occasion, but it
+don't amount to anything now. This one makes it sing mighty small, I'm
+willing to allow."
+
+The money was counted. The sum amounted to a little over twelve
+thousand dollars. It was more than any one present had ever seen at one
+time before, though several persons were there who were worth
+considerably more than that in property.
+
+
+
+CHAPTER XXXV
+
+THE reader may rest satisfied that Tom's and Huck's windfall made a
+mighty stir in the poor little village of St. Petersburg. So vast a
+sum, all in actual cash, seemed next to incredible. It was talked
+about, gloated over, glorified, until the reason of many of the
+citizens tottered under the strain of the unhealthy excitement. Every
+"haunted" house in St. Petersburg and the neighboring villages was
+dissected, plank by plank, and its foundations dug up and ransacked for
+hidden treasure--and not by boys, but men--pretty grave, unromantic
+men, too, some of them. Wherever Tom and Huck appeared they were
+courted, admired, stared at. The boys were not able to remember that
+their remarks had possessed weight before; but now their sayings were
+treasured and repeated; everything they did seemed somehow to be
+regarded as remarkable; they had evidently lost the power of doing and
+saying commonplace things; moreover, their past history was raked up
+and discovered to bear marks of conspicuous originality. The village
+paper published biographical sketches of the boys.
+
+The Widow Douglas put Huck's money out at six per cent., and Judge
+Thatcher did the same with Tom's at Aunt Polly's request. Each lad had
+an income, now, that was simply prodigious--a dollar for every week-day
+in the year and half of the Sundays. It was just what the minister got
+--no, it was what he was promised--he generally couldn't collect it. A
+dollar and a quarter a week would board, lodge, and school a boy in
+those old simple days--and clothe him and wash him, too, for that
+matter.
+
+Judge Thatcher had conceived a great opinion of Tom. He said that no
+commonplace boy would ever have got his daughter out of the cave. When
+Becky told her father, in strict confidence, how Tom had taken her
+whipping at school, the Judge was visibly moved; and when she pleaded
+grace for the mighty lie which Tom had told in order to shift that
+whipping from her shoulders to his own, the Judge said with a fine
+outburst that it was a noble, a generous, a magnanimous lie--a lie that
+was worthy to hold up its head and march down through history breast to
+breast with George Washington's lauded Truth about the hatchet! Becky
+thought her father had never looked so tall and so superb as when he
+walked the floor and stamped his foot and said that. She went straight
+off and told Tom about it.
+
+Judge Thatcher hoped to see Tom a great lawyer or a great soldier some
+day. He said he meant to look to it that Tom should be admitted to the
+National Military Academy and afterward trained in the best law school
+in the country, in order that he might be ready for either career or
+both.
+
+Huck Finn's wealth and the fact that he was now under the Widow
+Douglas' protection introduced him into society--no, dragged him into
+it, hurled him into it--and his sufferings were almost more than he
+could bear. The widow's servants kept him clean and neat, combed and
+brushed, and they bedded him nightly in unsympathetic sheets that had
+not one little spot or stain which he could press to his heart and know
+for a friend. He had to eat with a knife and fork; he had to use
+napkin, cup, and plate; he had to learn his book, he had to go to
+church; he had to talk so properly that speech was become insipid in
+his mouth; whithersoever he turned, the bars and shackles of
+civilization shut him in and bound him hand and foot.
+
+He bravely bore his miseries three weeks, and then one day turned up
+missing. For forty-eight hours the widow hunted for him everywhere in
+great distress. The public were profoundly concerned; they searched
+high and low, they dragged the river for his body. Early the third
+morning Tom Sawyer wisely went poking among some old empty hogsheads
+down behind the abandoned slaughter-house, and in one of them he found
+the refugee. Huck had slept there; he had just breakfasted upon some
+stolen odds and ends of food, and was lying off, now, in comfort, with
+his pipe. He was unkempt, uncombed, and clad in the same old ruin of
+rags that had made him picturesque in the days when he was free and
+happy. Tom routed him out, told him the trouble he had been causing,
+and urged him to go home. Huck's face lost its tranquil content, and
+took a melancholy cast. He said:
+
+"Don't talk about it, Tom. I've tried it, and it don't work; it don't
+work, Tom. It ain't for me; I ain't used to it. The widder's good to
+me, and friendly; but I can't stand them ways. She makes me get up just
+at the same time every morning; she makes me wash, they comb me all to
+thunder; she won't let me sleep in the woodshed; I got to wear them
+blamed clothes that just smothers me, Tom; they don't seem to any air
+git through 'em, somehow; and they're so rotten nice that I can't set
+down, nor lay down, nor roll around anywher's; I hain't slid on a
+cellar-door for--well, it 'pears to be years; I got to go to church and
+sweat and sweat--I hate them ornery sermons! I can't ketch a fly in
+there, I can't chaw. I got to wear shoes all Sunday. The widder eats by
+a bell; she goes to bed by a bell; she gits up by a bell--everything's
+so awful reg'lar a body can't stand it."
+
+"Well, everybody does that way, Huck."
+
+"Tom, it don't make no difference. I ain't everybody, and I can't
+STAND it. It's awful to be tied up so. And grub comes too easy--I don't
+take no interest in vittles, that way. I got to ask to go a-fishing; I
+got to ask to go in a-swimming--dern'd if I hain't got to ask to do
+everything. Well, I'd got to talk so nice it wasn't no comfort--I'd got
+to go up in the attic and rip out awhile, every day, to git a taste in
+my mouth, or I'd a died, Tom. The widder wouldn't let me smoke; she
+wouldn't let me yell, she wouldn't let me gape, nor stretch, nor
+scratch, before folks--" [Then with a spasm of special irritation and
+injury]--"And dad fetch it, she prayed all the time! I never see such a
+woman! I HAD to shove, Tom--I just had to. And besides, that school's
+going to open, and I'd a had to go to it--well, I wouldn't stand THAT,
+Tom. Looky here, Tom, being rich ain't what it's cracked up to be. It's
+just worry and worry, and sweat and sweat, and a-wishing you was dead
+all the time. Now these clothes suits me, and this bar'l suits me, and
+I ain't ever going to shake 'em any more. Tom, I wouldn't ever got into
+all this trouble if it hadn't 'a' ben for that money; now you just take
+my sheer of it along with your'n, and gimme a ten-center sometimes--not
+many times, becuz I don't give a dern for a thing 'thout it's tollable
+hard to git--and you go and beg off for me with the widder."
+
+"Oh, Huck, you know I can't do that. 'Tain't fair; and besides if
+you'll try this thing just a while longer you'll come to like it."
+
+"Like it! Yes--the way I'd like a hot stove if I was to set on it long
+enough. No, Tom, I won't be rich, and I won't live in them cussed
+smothery houses. I like the woods, and the river, and hogsheads, and
+I'll stick to 'em, too. Blame it all! just as we'd got guns, and a
+cave, and all just fixed to rob, here this dern foolishness has got to
+come up and spile it all!"
+
+Tom saw his opportunity--
+
+"Lookyhere, Huck, being rich ain't going to keep me back from turning
+robber."
+
+"No! Oh, good-licks; are you in real dead-wood earnest, Tom?"
+
+"Just as dead earnest as I'm sitting here. But Huck, we can't let you
+into the gang if you ain't respectable, you know."
+
+Huck's joy was quenched.
+
+"Can't let me in, Tom? Didn't you let me go for a pirate?"
+
+"Yes, but that's different. A robber is more high-toned than what a
+pirate is--as a general thing. In most countries they're awful high up
+in the nobility--dukes and such."
+
+"Now, Tom, hain't you always ben friendly to me? You wouldn't shet me
+out, would you, Tom? You wouldn't do that, now, WOULD you, Tom?"
+
+"Huck, I wouldn't want to, and I DON'T want to--but what would people
+say? Why, they'd say, 'Mph! Tom Sawyer's Gang! pretty low characters in
+it!' They'd mean you, Huck. You wouldn't like that, and I wouldn't."
+
+Huck was silent for some time, engaged in a mental struggle. Finally
+he said:
+
+"Well, I'll go back to the widder for a month and tackle it and see if
+I can come to stand it, if you'll let me b'long to the gang, Tom."
+
+"All right, Huck, it's a whiz! Come along, old chap, and I'll ask the
+widow to let up on you a little, Huck."
+
+"Will you, Tom--now will you? That's good. If she'll let up on some of
+the roughest things, I'll smoke private and cuss private, and crowd
+through or bust. When you going to start the gang and turn robbers?"
+
+"Oh, right off. We'll get the boys together and have the initiation
+to-night, maybe."
+
+"Have the which?"
+
+"Have the initiation."
+
+"What's that?"
+
+"It's to swear to stand by one another, and never tell the gang's
+secrets, even if you're chopped all to flinders, and kill anybody and
+all his family that hurts one of the gang."
+
+"That's gay--that's mighty gay, Tom, I tell you."
+
+"Well, I bet it is. And all that swearing's got to be done at
+midnight, in the lonesomest, awfulest place you can find--a ha'nted
+house is the best, but they're all ripped up now."
+
+"Well, midnight's good, anyway, Tom."
+
+"Yes, so it is. And you've got to swear on a coffin, and sign it with
+blood."
+
+"Now, that's something LIKE! Why, it's a million times bullier than
+pirating. I'll stick to the widder till I rot, Tom; and if I git to be
+a reg'lar ripper of a robber, and everybody talking 'bout it, I reckon
+she'll be proud she snaked me in out of the wet."
+
+
+
+CONCLUSION
+
+SO endeth this chronicle. It being strictly a history of a BOY, it
+must stop here; the story could not go much further without becoming
+the history of a MAN. When one writes a novel about grown people, he
+knows exactly where to stop--that is, with a marriage; but when he
+writes of juveniles, he must stop where he best can.
+
+Most of the characters that perform in this book still live, and are
+prosperous and happy. Some day it may seem worth while to take up the
+story of the younger ones again and see what sort of men and women they
+turned out to be; therefore it will be wisest not to reveal any of that
+part of their lives at present.
diff --git a/libgo/go/net/textproto/header.go b/libgo/go/net/textproto/header.go
index 7fb32f8045e..2e2752a7558 100644
--- a/libgo/go/net/textproto/header.go
+++ b/libgo/go/net/textproto/header.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -16,7 +16,7 @@ func (h MIMEHeader) Add(key, value string) {
 }
 
 // Set sets the header entries associated with key to
-// the single element value.  It replaces any existing
+// the single element value. It replaces any existing
 // values associated with key.
 func (h MIMEHeader) Set(key, value string) {
 	h[CanonicalMIMEHeaderKey(key)] = []string{value}
@@ -24,7 +24,7 @@ func (h MIMEHeader) Set(key, value string) {
 
 // Get gets the first value associated with the given key.
 // If there are no values associated with the key, Get returns "".
-// Get is a convenience method.  For more complex queries,
+// Get is a convenience method. For more complex queries,
 // access the map directly.
 func (h MIMEHeader) Get(key string) string {
 	if h == nil {
diff --git a/libgo/go/net/textproto/pipeline.go b/libgo/go/net/textproto/pipeline.go
index ca50eddac38..2e283218b50 100644
--- a/libgo/go/net/textproto/pipeline.go
+++ b/libgo/go/net/textproto/pipeline.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -66,8 +66,8 @@ func (p *Pipeline) EndResponse(id uint) {
 }
 
 // A sequencer schedules a sequence of numbered events that must
-// happen in order, one after the other.  The event numbering must start
-// at 0 and increment without skipping.  The event number wraps around
+// happen in order, one after the other. The event numbering must start
+// at 0 and increment without skipping. The event number wraps around
 // safely as long as there are not 2^32 simultaneous events pending.
 type sequencer struct {
 	mu   sync.Mutex
diff --git a/libgo/go/net/textproto/reader.go b/libgo/go/net/textproto/reader.go
index 91bbb573043..e07d1d62e09 100644
--- a/libgo/go/net/textproto/reader.go
+++ b/libgo/go/net/textproto/reader.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -71,7 +71,7 @@ func (r *Reader) readLineSlice() ([]byte, error) {
 // ReadContinuedLine reads a possibly continued line from r,
 // eliding the final trailing ASCII white space.
 // Lines after the first are considered continuations if they
-// begin with a space or tab character.  In the returned data,
+// begin with a space or tab character. In the returned data,
 // continuation lines are separated from the previous line
 // only by a single space: the newline and leading white space
 // are removed.
@@ -204,7 +204,7 @@ func parseCodeLine(line string, expectCode int) (code int, continued bool, messa
 // ReadCodeLine reads a response code line of the form
 //	code message
 // where code is a three-digit status code and the message
-// extends to the rest of the line.  An example of such a line is:
+// extends to the rest of the line. An example of such a line is:
 //	220 plan9.bell-labs.com ESMTP
 //
 // If the prefix of the status does not match the digits in expectCode,
@@ -366,7 +366,7 @@ func (d *dotReader) Read(b []byte) (n int, err error) {
 				d.state = stateBeginLine
 				break
 			}
-			// Not part of \r\n.  Emit saved \r
+			// Not part of \r\n. Emit saved \r
 			br.UnreadByte()
 			c = '\r'
 			d.state = stateData
@@ -552,9 +552,9 @@ func (r *Reader) upcomingHeaderNewlines() (n int) {
 }
 
 // CanonicalMIMEHeaderKey returns the canonical format of the
-// MIME header key s.  The canonicalization converts the first
+// MIME header key s. The canonicalization converts the first
 // letter and any letter following a hyphen to upper case;
-// the rest are converted to lowercase.  For example, the
+// the rest are converted to lowercase. For example, the
 // canonical key for "accept-encoding" is "Accept-Encoding".
 // MIME header keys are assumed to be ASCII only.
 // If s contains a space or invalid header field bytes, it is
@@ -581,18 +581,14 @@ func CanonicalMIMEHeaderKey(s string) string {
 const toLower = 'a' - 'A'
 
 // validHeaderFieldByte reports whether b is a valid byte in a header
-// field key. This is actually stricter than RFC 7230, which says:
+// field name. RFC 7230 says:
+//   header-field   = field-name ":" OWS field-value OWS
+//   field-name     = token
 //   tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
 //           "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA
 //   token = 1*tchar
-// TODO: revisit in Go 1.6+ and possibly expand this. But note that many
-// servers have historically dropped '_' to prevent ambiguities when mapping
-// to CGI environment variables.
 func validHeaderFieldByte(b byte) bool {
-	return ('A' <= b && b <= 'Z') ||
-		('a' <= b && b <= 'z') ||
-		('0' <= b && b <= '9') ||
-		b == '-'
+	return int(b) < len(isTokenTable) && isTokenTable[b]
 }
 
 // canonicalMIMEHeaderKey is like CanonicalMIMEHeaderKey but is
@@ -682,3 +678,85 @@ func init() {
 		commonHeader[v] = v
 	}
 }
+
+// isTokenTable is a copy of net/http/lex.go's isTokenTable.
+// See https://httpwg.github.io/specs/rfc7230.html#rule.token.separators
+var isTokenTable = [127]bool{
+	'!':  true,
+	'#':  true,
+	'$':  true,
+	'%':  true,
+	'&':  true,
+	'\'': true,
+	'*':  true,
+	'+':  true,
+	'-':  true,
+	'.':  true,
+	'0':  true,
+	'1':  true,
+	'2':  true,
+	'3':  true,
+	'4':  true,
+	'5':  true,
+	'6':  true,
+	'7':  true,
+	'8':  true,
+	'9':  true,
+	'A':  true,
+	'B':  true,
+	'C':  true,
+	'D':  true,
+	'E':  true,
+	'F':  true,
+	'G':  true,
+	'H':  true,
+	'I':  true,
+	'J':  true,
+	'K':  true,
+	'L':  true,
+	'M':  true,
+	'N':  true,
+	'O':  true,
+	'P':  true,
+	'Q':  true,
+	'R':  true,
+	'S':  true,
+	'T':  true,
+	'U':  true,
+	'W':  true,
+	'V':  true,
+	'X':  true,
+	'Y':  true,
+	'Z':  true,
+	'^':  true,
+	'_':  true,
+	'`':  true,
+	'a':  true,
+	'b':  true,
+	'c':  true,
+	'd':  true,
+	'e':  true,
+	'f':  true,
+	'g':  true,
+	'h':  true,
+	'i':  true,
+	'j':  true,
+	'k':  true,
+	'l':  true,
+	'm':  true,
+	'n':  true,
+	'o':  true,
+	'p':  true,
+	'q':  true,
+	'r':  true,
+	's':  true,
+	't':  true,
+	'u':  true,
+	'v':  true,
+	'w':  true,
+	'x':  true,
+	'y':  true,
+	'z':  true,
+	'|':  true,
+	'~':  true,
+}
diff --git a/libgo/go/net/textproto/reader_test.go b/libgo/go/net/textproto/reader_test.go
index 93d7939bb5f..0c53d48b74a 100644
--- a/libgo/go/net/textproto/reader_test.go
+++ b/libgo/go/net/textproto/reader_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -25,6 +25,12 @@ var canonicalHeaderKeyTests = []canonicalHeaderKeyTest{
 	{"user-agent", "User-Agent"},
 	{"USER-AGENT", "User-Agent"},
 
+	// Other valid tchar bytes in tokens:
+	{"foo-bar_baz", "Foo-Bar_baz"},
+	{"foo-bar$baz", "Foo-Bar$baz"},
+	{"foo-bar~baz", "Foo-Bar~baz"},
+	{"foo-bar*baz", "Foo-Bar*baz"},
+
 	// Non-ASCII or anything with spaces or non-token chars is unchanged:
 	{"üser-agenT", "üser-agenT"},
 	{"a B", "a B"},
diff --git a/libgo/go/net/textproto/textproto.go b/libgo/go/net/textproto/textproto.go
index 026eb026b1d..8fd781e7775 100644
--- a/libgo/go/net/textproto/textproto.go
+++ b/libgo/go/net/textproto/textproto.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -87,7 +87,7 @@ func Dial(network, addr string) (*Conn, error) {
 }
 
 // Cmd is a convenience method that sends a command after
-// waiting its turn in the pipeline.  The command text is the
+// waiting its turn in the pipeline. The command text is the
 // result of formatting format with args and appending \r\n.
 // Cmd returns the id of the command, for use with StartResponse and EndResponse.
 //
diff --git a/libgo/go/net/textproto/writer.go b/libgo/go/net/textproto/writer.go
index 03e2fd658e4..1bc5974c6c2 100644
--- a/libgo/go/net/textproto/writer.go
+++ b/libgo/go/net/textproto/writer.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -36,7 +36,7 @@ func (w *Writer) PrintfLine(format string, args ...interface{}) error {
 // DotWriter returns a writer that can be used to write a dot-encoding to w.
 // It takes care of inserting leading dots when necessary,
 // translating line-ending \n into \r\n, and adding the final .\r\n line
-// when the DotWriter is closed.  The caller should close the
+// when the DotWriter is closed. The caller should close the
 // DotWriter before the next call to a method on w.
 //
 // See the documentation for Reader's DotReader method for details about dot-encoding.
diff --git a/libgo/go/net/textproto/writer_test.go b/libgo/go/net/textproto/writer_test.go
index e03ab5e15f6..ac03669fa2d 100644
--- a/libgo/go/net/textproto/writer_test.go
+++ b/libgo/go/net/textproto/writer_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/net/timeout_test.go b/libgo/go/net/timeout_test.go
index 98e3164fb98..ed26f2a4aff 100644
--- a/libgo/go/net/timeout_test.go
+++ b/libgo/go/net/timeout_test.go
@@ -5,7 +5,9 @@
 package net
 
 import (
+	"context"
 	"fmt"
+	"internal/testenv"
 	"io"
 	"io/ioutil"
 	"net/internal/socktest"
@@ -26,6 +28,8 @@ var dialTimeoutTests = []struct {
 	{-5 * time.Second, 0, -5 * time.Second, 100 * time.Millisecond},
 	{0, -5 * time.Second, -5 * time.Second, 100 * time.Millisecond},
 	{-5 * time.Second, 5 * time.Second, -5 * time.Second, 100 * time.Millisecond}, // timeout over deadline
+	{-1 << 63, 0, time.Second, 100 * time.Millisecond},
+	{0, -1 << 63, time.Second, 100 * time.Millisecond},
 
 	{50 * time.Millisecond, 0, 100 * time.Millisecond, time.Second},
 	{0, 50 * time.Millisecond, 100 * time.Millisecond, time.Second},
@@ -38,19 +42,6 @@ func TestDialTimeout(t *testing.T) {
 	defer func() { testHookDialChannel = origTestHookDialChannel }()
 	defer sw.Set(socktest.FilterConnect, nil)
 
-	// Avoid tracking open-close jitterbugs between netFD and
-	// socket that leads to confusion of information inside
-	// socktest.Switch.
-	// It may happen when the Dial call bumps against TCP
-	// simultaneous open. See selfConnect in tcpsock_posix.go.
-	defer func() {
-		sw.Set(socktest.FilterClose, nil)
-		forceCloseSockets()
-	}()
-	sw.Set(socktest.FilterClose, func(so *socktest.Status) (socktest.AfterFilter, error) {
-		return nil, errTimedout
-	})
-
 	for i, tt := range dialTimeoutTests {
 		switch runtime.GOOS {
 		case "plan9", "windows":
@@ -99,6 +90,56 @@ func TestDialTimeout(t *testing.T) {
 	}
 }
 
+var dialTimeoutMaxDurationTests = []struct {
+	timeout time.Duration
+	delta   time.Duration // for deadline
+}{
+	// Large timeouts that will overflow an int64 unix nanos.
+	{1<<63 - 1, 0},
+	{0, 1<<63 - 1},
+}
+
+func TestDialTimeoutMaxDuration(t *testing.T) {
+	if runtime.GOOS == "openbsd" {
+		testenv.SkipFlaky(t, 15157)
+	}
+
+	ln, err := newLocalListener("tcp")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+
+	for i, tt := range dialTimeoutMaxDurationTests {
+		ch := make(chan error)
+		max := time.NewTimer(250 * time.Millisecond)
+		defer max.Stop()
+		go func() {
+			d := Dialer{Timeout: tt.timeout}
+			if tt.delta != 0 {
+				d.Deadline = time.Now().Add(tt.delta)
+			}
+			c, err := d.Dial(ln.Addr().Network(), ln.Addr().String())
+			if err == nil {
+				c.Close()
+			}
+			ch <- err
+		}()
+
+		select {
+		case <-max.C:
+			t.Fatalf("#%d: Dial didn't return in an expected time", i)
+		case err := <-ch:
+			if perr := parseDialError(err); perr != nil {
+				t.Error(perr)
+			}
+			if err != nil {
+				t.Errorf("#%d: %v", i, err)
+			}
+		}
+	}
+}
+
 var acceptTimeoutTests = []struct {
 	timeout time.Duration
 	xerrs   [2]error // expected errors in transition
@@ -124,10 +165,13 @@ func TestAcceptTimeout(t *testing.T) {
 	}
 	defer ln.Close()
 
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
 	for i, tt := range acceptTimeoutTests {
 		if tt.timeout < 0 {
 			go func() {
-				c, err := Dial(ln.Addr().Network(), ln.Addr().String())
+				var d Dialer
+				c, err := d.DialContext(ctx, ln.Addr().Network(), ln.Addr().String())
 				if err != nil {
 					t.Error(err)
 					return
@@ -261,8 +305,6 @@ var readTimeoutTests = []struct {
 }
 
 func TestReadTimeout(t *testing.T) {
-	t.Parallel()
-
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skipf("not supported on %s", runtime.GOOS)
diff --git a/libgo/go/net/udpsock.go b/libgo/go/net/udpsock.go
index 9292133aeb8..980f67c81f9 100644
--- a/libgo/go/net/udpsock.go
+++ b/libgo/go/net/udpsock.go
@@ -1,9 +1,14 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
+import (
+	"context"
+	"syscall"
+)
+
 // UDPAddr represents the address of a UDP end point.
 type UDPAddr struct {
 	IP   IP
@@ -53,9 +58,185 @@ func ResolveUDPAddr(net, addr string) (*UDPAddr, error) {
 	default:
 		return nil, UnknownNetworkError(net)
 	}
-	addrs, err := internetAddrList(net, addr, noDeadline)
+	addrs, err := internetAddrList(context.Background(), net, addr)
 	if err != nil {
 		return nil, err
 	}
 	return addrs.first(isIPv4).(*UDPAddr), nil
 }
+
+// UDPConn is the implementation of the Conn and PacketConn interfaces
+// for UDP network connections.
+type UDPConn struct {
+	conn
+}
+
+// ReadFromUDP reads a UDP packet from c, copying the payload into b.
+// It returns the number of bytes copied into b and the return address
+// that was on the packet.
+//
+// ReadFromUDP can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetReadDeadline.
+func (c *UDPConn) ReadFromUDP(b []byte) (int, *UDPAddr, error) {
+	if !c.ok() {
+		return 0, nil, syscall.EINVAL
+	}
+	n, addr, err := c.readFrom(b)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return n, addr, err
+}
+
+// ReadFrom implements the PacketConn ReadFrom method.
+func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
+	if !c.ok() {
+		return 0, nil, syscall.EINVAL
+	}
+	n, addr, err := c.readFrom(b)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	if addr == nil {
+		return n, nil, err
+	}
+	return n, addr, err
+}
+
+// ReadMsgUDP reads a packet from c, copying the payload into b and
+// the associated out-of-band data into oob. It returns the number
+// of bytes copied into b, the number of bytes copied into oob, the
+// flags that were set on the packet and the source address of the
+// packet.
+func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
+	if !c.ok() {
+		return 0, 0, 0, nil, syscall.EINVAL
+	}
+	n, oobn, flags, addr, err = c.readMsg(b, oob)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return
+}
+
+// WriteToUDP writes a UDP packet to addr via c, copying the payload
+// from b.
+//
+// WriteToUDP can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetWriteDeadline. On packet-oriented connections, write timeouts
+// are rare.
+func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	n, err := c.writeTo(b, addr)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	}
+	return n, err
+}
+
+// WriteTo implements the PacketConn WriteTo method.
+func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	a, ok := addr.(*UDPAddr)
+	if !ok {
+		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
+	}
+	n, err := c.writeTo(b, a)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
+	}
+	return n, err
+}
+
+// WriteMsgUDP writes a packet to addr via c if c isn't connected, or
+// to c's remote destination address if c is connected (in which case
+// addr must be nil).  The payload is copied from b and the associated
+// out-of-band data is copied from oob. It returns the number of
+// payload and out-of-band bytes written.
+func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
+	if !c.ok() {
+		return 0, 0, syscall.EINVAL
+	}
+	n, oobn, err = c.writeMsg(b, oob, addr)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	}
+	return
+}
+
+func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
+
+// DialUDP connects to the remote address raddr on the network net,
+// which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is
+// used as the local address for the connection.
+func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
+	switch net {
+	case "udp", "udp4", "udp6":
+	default:
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if raddr == nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
+	}
+	c, err := dialUDP(context.Background(), net, laddr, raddr)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
+
+// ListenUDP listens for incoming UDP packets addressed to the local
+// address laddr. Net must be "udp", "udp4", or "udp6".  If laddr has
+// a port of 0, ListenUDP will choose an available port.
+// The LocalAddr method of the returned UDPConn can be used to
+// discover the port. The returned connection's ReadFrom and WriteTo
+// methods can be used to receive and send UDP packets with per-packet
+// addressing.
+func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
+	switch net {
+	case "udp", "udp4", "udp6":
+	default:
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if laddr == nil {
+		laddr = &UDPAddr{}
+	}
+	c, err := listenUDP(context.Background(), net, laddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
+
+// ListenMulticastUDP listens for incoming multicast UDP packets
+// addressed to the group address gaddr on the interface ifi.
+// Network must be "udp", "udp4" or "udp6".
+// ListenMulticastUDP uses the system-assigned multicast interface
+// when ifi is nil, although this is not recommended because the
+// assignment depends on platforms and sometimes it might require
+// routing configuration.
+//
+// ListenMulticastUDP is just for convenience of simple, small
+// applications. There are golang.org/x/net/ipv4 and
+// golang.org/x/net/ipv6 packages for general purpose uses.
+func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
+	switch network {
+	case "udp", "udp4", "udp6":
+	default:
+		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
+	}
+	if gaddr == nil || gaddr.IP == nil {
+		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
+	}
+	c, err := listenMulticastUDP(context.Background(), network, ifi, gaddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
diff --git a/libgo/go/net/udpsock_plan9.go b/libgo/go/net/udpsock_plan9.go
index 1ba57a227e9..666f20622f6 100644
--- a/libgo/go/net/udpsock_plan9.go
+++ b/libgo/go/net/udpsock_plan9.go
@@ -1,42 +1,24 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"context"
 	"errors"
 	"os"
 	"syscall"
-	"time"
 )
 
-// UDPConn is the implementation of the Conn and PacketConn interfaces
-// for UDP network connections.
-type UDPConn struct {
-	conn
-}
-
-func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
-
-// ReadFromUDP reads a UDP packet from c, copying the payload into b.
-// It returns the number of bytes copied into b and the return address
-// that was on the packet.
-//
-// ReadFromUDP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetReadDeadline.
-func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
-	if !c.ok() || c.fd.data == nil {
-		return 0, nil, syscall.EINVAL
-	}
+func (c *UDPConn) readFrom(b []byte) (n int, addr *UDPAddr, err error) {
 	buf := make([]byte, udpHeaderSize+len(b))
-	m, err := c.fd.data.Read(buf)
+	m, err := c.fd.Read(buf)
 	if err != nil {
-		return 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+		return 0, nil, err
 	}
 	if m < udpHeaderSize {
-		return 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: errors.New("short read reading UDP header")}
+		return 0, nil, errors.New("short read reading UDP header")
 	}
 	buf = buf[:m]
 
@@ -45,36 +27,13 @@ func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
 	return n, &UDPAddr{IP: h.raddr, Port: int(h.rport)}, nil
 }
 
-// ReadFrom implements the PacketConn ReadFrom method.
-func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
-	return c.ReadFromUDP(b)
+func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
+	return 0, 0, 0, nil, syscall.EPLAN9
 }
 
-// ReadMsgUDP reads a packet from c, copying the payload into b and
-// the associated out-of-band data into oob.  It returns the number
-// of bytes copied into b, the number of bytes copied into oob, the
-// flags that were set on the packet and the source address of the
-// packet.
-func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
-	return 0, 0, 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
-}
-
-// WriteToUDP writes a UDP packet to addr via c, copying the payload
-// from b.
-//
-// WriteToUDP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetWriteDeadline.  On packet-oriented connections, write timeouts
-// are rare.
-func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
-	if !c.ok() || c.fd.data == nil {
-		return 0, syscall.EINVAL
-	}
+func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
 	if addr == nil {
-		return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
+		return 0, errMissingAddress
 	}
 	h := new(udpHeader)
 	h.raddr = addr.IP.To16()
@@ -86,53 +45,18 @@ func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
 	buf := make([]byte, udpHeaderSize+len(b))
 	i := copy(buf, h.Bytes())
 	copy(buf[i:], b)
-	if _, err := c.fd.data.Write(buf); err != nil {
-		return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	if _, err := c.fd.Write(buf); err != nil {
+		return 0, err
 	}
 	return len(b), nil
 }
 
-// WriteTo implements the PacketConn WriteTo method.
-func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
-	a, ok := addr.(*UDPAddr)
-	if !ok {
-		return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
-	}
-	return c.WriteToUDP(b, a)
+func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
+	return 0, 0, syscall.EPLAN9
 }
 
-// WriteMsgUDP writes a packet to addr via c if c isn't connected, or
-// to c's remote destination address if c is connected (in which case
-// addr must be nil).  The payload is copied from b and the associated
-// out-of-band data is copied from oob.  It returns the number of
-// payload and out-of-band bytes written.
-func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
-	return 0, 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EPLAN9}
-}
-
-// DialUDP connects to the remote address raddr on the network net,
-// which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is
-// used as the local address for the connection.
-func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
-	return dialUDP(net, laddr, raddr, noDeadline)
-}
-
-func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, error) {
-	if !deadline.IsZero() {
-		panic("net.dialUDP: deadline not implemented on Plan 9")
-	}
-	switch net {
-	case "udp", "udp4", "udp6":
-	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
-	}
-	fd, err := dialPlan9(net, laddr, raddr)
+func dialUDP(ctx context.Context, net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
+	fd, err := dialPlan9(ctx, net, laddr, raddr)
 	if err != nil {
 		return nil, err
 	}
@@ -167,49 +91,23 @@ func unmarshalUDPHeader(b []byte) (*udpHeader, []byte) {
 	return h, b
 }
 
-// ListenUDP listens for incoming UDP packets addressed to the local
-// address laddr.  Net must be "udp", "udp4", or "udp6".  If laddr has
-// a port of 0, ListenUDP will choose an available port.
-// The LocalAddr method of the returned UDPConn can be used to
-// discover the port.  The returned connection's ReadFrom and WriteTo
-// methods can be used to receive and send UDP packets with per-packet
-// addressing.
-func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
-	switch net {
-	case "udp", "udp4", "udp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		laddr = &UDPAddr{}
-	}
-	l, err := listenPlan9(net, laddr)
+func listenUDP(ctx context.Context, network string, laddr *UDPAddr) (*UDPConn, error) {
+	l, err := listenPlan9(ctx, network, laddr)
 	if err != nil {
 		return nil, err
 	}
 	_, err = l.ctl.WriteString("headers")
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	l.data, err = os.OpenFile(l.dir+"/data", os.O_RDWR, 0)
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	fd, err := l.netFD()
 	return newUDPConn(fd), err
 }
 
-// ListenMulticastUDP listens for incoming multicast UDP packets
-// addressed to the group address gaddr on the interface ifi.
-// Network must be "udp", "udp4" or "udp6".
-// ListenMulticastUDP uses the system-assigned multicast interface
-// when ifi is nil, although this is not recommended because the
-// assignment depends on platforms and sometimes it might require
-// routing configuration.
-//
-// ListenMulticastUDP is just for convenience of simple, small
-// applications. There are golang.org/x/net/ipv4 and
-// golang.org/x/net/ipv6 packages for general purpose uses.
-func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
-	return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: syscall.EPLAN9}
+func listenMulticastUDP(ctx context.Context, network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
+	return nil, syscall.EPLAN9
 }
diff --git a/libgo/go/net/udpsock_posix.go b/libgo/go/net/udpsock_posix.go
index 932c6ce713f..4924801ebb2 100644
--- a/libgo/go/net/udpsock_posix.go
+++ b/libgo/go/net/udpsock_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,8 +7,8 @@
 package net
 
 import (
+	"context"
 	"syscall"
-	"time"
 )
 
 func sockaddrToUDP(sa syscall.Sockaddr) Addr {
@@ -38,25 +38,7 @@ func (a *UDPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, a.Port, a.Zone)
 }
 
-// UDPConn is the implementation of the Conn and PacketConn interfaces
-// for UDP network connections.
-type UDPConn struct {
-	conn
-}
-
-func newUDPConn(fd *netFD) *UDPConn { return &UDPConn{conn{fd}} }
-
-// ReadFromUDP reads a UDP packet from c, copying the payload into b.
-// It returns the number of bytes copied into b and the return address
-// that was on the packet.
-//
-// ReadFromUDP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetReadDeadline.
-func (c *UDPConn) ReadFromUDP(b []byte) (int, *UDPAddr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
+func (c *UDPConn) readFrom(b []byte) (int, *UDPAddr, error) {
 	var addr *UDPAddr
 	n, sa, err := c.fd.readFrom(b)
 	switch sa := sa.(type) {
@@ -65,33 +47,10 @@ func (c *UDPConn) ReadFromUDP(b []byte) (int, *UDPAddr, error) {
 	case *syscall.SockaddrInet6:
 		addr = &UDPAddr{IP: sa.Addr[0:], Port: sa.Port, Zone: zoneToString(int(sa.ZoneId))}
 	}
-	if err != nil {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return n, addr, err
-}
-
-// ReadFrom implements the PacketConn ReadFrom method.
-func (c *UDPConn) ReadFrom(b []byte) (int, Addr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
-	n, addr, err := c.ReadFromUDP(b)
-	if addr == nil {
-		return n, nil, err
-	}
 	return n, addr, err
 }
 
-// ReadMsgUDP reads a packet from c, copying the payload into b and
-// the associated out-of-band data into oob.  It returns the number
-// of bytes copied into b, the number of bytes copied into oob, the
-// flags that were set on the packet and the source address of the
-// packet.
-func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
-	if !c.ok() {
-		return 0, 0, 0, nil, syscall.EINVAL
-	}
+func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error) {
 	var sa syscall.Sockaddr
 	n, oobn, flags, sa, err = c.fd.readMsg(b, oob)
 	switch sa := sa.(type) {
@@ -100,159 +59,68 @@ func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr,
 	case *syscall.SockaddrInet6:
 		addr = &UDPAddr{IP: sa.Addr[0:], Port: sa.Port, Zone: zoneToString(int(sa.ZoneId))}
 	}
-	if err != nil {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
 	return
 }
 
-// WriteToUDP writes a UDP packet to addr via c, copying the payload
-// from b.
-//
-// WriteToUDP can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetWriteDeadline.  On packet-oriented connections, write timeouts
-// are rare.
-func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (int, error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
+func (c *UDPConn) writeTo(b []byte, addr *UDPAddr) (int, error) {
 	if c.fd.isConnected {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
+		return 0, ErrWriteToConnected
 	}
 	if addr == nil {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
+		return 0, errMissingAddress
 	}
 	sa, err := addr.sockaddr(c.fd.family)
 	if err != nil {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
-	}
-	n, err := c.fd.writeTo(b, sa)
-	if err != nil {
-		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+		return 0, err
 	}
-	return n, err
+	return c.fd.writeTo(b, sa)
 }
 
-// WriteTo implements the PacketConn WriteTo method.
-func (c *UDPConn) WriteTo(b []byte, addr Addr) (int, error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
-	a, ok := addr.(*UDPAddr)
-	if !ok {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
-	}
-	return c.WriteToUDP(b, a)
-}
-
-// WriteMsgUDP writes a packet to addr via c if c isn't connected, or
-// to c's remote destination address if c is connected (in which case
-// addr must be nil).  The payload is copied from b and the associated
-// out-of-band data is copied from oob.  It returns the number of
-// payload and out-of-band bytes written.
-func (c *UDPConn) WriteMsgUDP(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
-	if !c.ok() {
-		return 0, 0, syscall.EINVAL
-	}
+func (c *UDPConn) writeMsg(b, oob []byte, addr *UDPAddr) (n, oobn int, err error) {
 	if c.fd.isConnected && addr != nil {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
+		return 0, 0, ErrWriteToConnected
 	}
 	if !c.fd.isConnected && addr == nil {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: errMissingAddress}
+		return 0, 0, errMissingAddress
 	}
-	var sa syscall.Sockaddr
-	sa, err = addr.sockaddr(c.fd.family)
-	if err != nil {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
-	}
-	n, oobn, err = c.fd.writeMsg(b, oob, sa)
+	sa, err := addr.sockaddr(c.fd.family)
 	if err != nil {
-		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+		return 0, 0, err
 	}
-	return
-}
-
-// DialUDP connects to the remote address raddr on the network net,
-// which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is
-// used as the local address for the connection.
-func DialUDP(net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
-	switch net {
-	case "udp", "udp4", "udp6":
-	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if raddr == nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
-	}
-	return dialUDP(net, laddr, raddr, noDeadline)
+	return c.fd.writeMsg(b, oob, sa)
 }
 
-func dialUDP(net string, laddr, raddr *UDPAddr, deadline time.Time) (*UDPConn, error) {
-	fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_DGRAM, 0, "dial", noCancel)
+func dialUDP(ctx context.Context, net string, laddr, raddr *UDPAddr) (*UDPConn, error) {
+	fd, err := internetSocket(ctx, net, laddr, raddr, syscall.SOCK_DGRAM, 0, "dial")
 	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newUDPConn(fd), nil
 }
 
-// ListenUDP listens for incoming UDP packets addressed to the local
-// address laddr.  Net must be "udp", "udp4", or "udp6".  If laddr has
-// a port of 0, ListenUDP will choose an available port.
-// The LocalAddr method of the returned UDPConn can be used to
-// discover the port.  The returned connection's ReadFrom and WriteTo
-// methods can be used to receive and send UDP packets with per-packet
-// addressing.
-func ListenUDP(net string, laddr *UDPAddr) (*UDPConn, error) {
-	switch net {
-	case "udp", "udp4", "udp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		laddr = &UDPAddr{}
-	}
-	fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_DGRAM, 0, "listen", noCancel)
+func listenUDP(ctx context.Context, network string, laddr *UDPAddr) (*UDPConn, error) {
+	fd, err := internetSocket(ctx, network, laddr, nil, syscall.SOCK_DGRAM, 0, "listen")
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr, Err: err}
+		return nil, err
 	}
 	return newUDPConn(fd), nil
 }
 
-// ListenMulticastUDP listens for incoming multicast UDP packets
-// addressed to the group address gaddr on the interface ifi.
-// Network must be "udp", "udp4" or "udp6".
-// ListenMulticastUDP uses the system-assigned multicast interface
-// when ifi is nil, although this is not recommended because the
-// assignment depends on platforms and sometimes it might require
-// routing configuration.
-//
-// ListenMulticastUDP is just for convenience of simple, small
-// applications. There are golang.org/x/net/ipv4 and
-// golang.org/x/net/ipv6 packages for general purpose uses.
-func ListenMulticastUDP(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
-	switch network {
-	case "udp", "udp4", "udp6":
-	default:
-		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: UnknownNetworkError(network)}
-	}
-	if gaddr == nil || gaddr.IP == nil {
-		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr.opAddr(), Err: errMissingAddress}
-	}
-	fd, err := internetSocket(network, gaddr, nil, noDeadline, syscall.SOCK_DGRAM, 0, "listen", noCancel)
+func listenMulticastUDP(ctx context.Context, network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error) {
+	fd, err := internetSocket(ctx, network, gaddr, nil, syscall.SOCK_DGRAM, 0, "listen")
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: gaddr, Err: err}
+		return nil, err
 	}
 	c := newUDPConn(fd)
 	if ip4 := gaddr.IP.To4(); ip4 != nil {
 		if err := listenIPv4MulticastUDP(c, ifi, ip4); err != nil {
 			c.Close()
-			return nil, &OpError{Op: "listen", Net: network, Source: c.fd.laddr, Addr: &IPAddr{IP: ip4}, Err: err}
+			return nil, err
 		}
 	} else {
 		if err := listenIPv6MulticastUDP(c, ifi, gaddr.IP); err != nil {
 			c.Close()
-			return nil, &OpError{Op: "listen", Net: network, Source: c.fd.laddr, Addr: &IPAddr{IP: gaddr.IP}, Err: err}
+			return nil, err
 		}
 	}
 	return c, nil
diff --git a/libgo/go/net/udp_test.go b/libgo/go/net/udpsock_test.go
index b25f96a3fd3..29d769c5a58 100644
--- a/libgo/go/net/udp_test.go
+++ b/libgo/go/net/udpsock_test.go
@@ -1,16 +1,54 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"internal/testenv"
 	"reflect"
 	"runtime"
 	"testing"
 	"time"
 )
 
+func BenchmarkUDP6LinkLocalUnicast(b *testing.B) {
+	testHookUninstaller.Do(uninstallTestHooks)
+
+	if !supportsIPv6 {
+		b.Skip("IPv6 is not supported")
+	}
+	ifi := loopbackInterface()
+	if ifi == nil {
+		b.Skip("loopback interface not found")
+	}
+	lla := ipv6LinkLocalUnicastAddr(ifi)
+	if lla == "" {
+		b.Skip("IPv6 link-local unicast address not found")
+	}
+
+	c1, err := ListenPacket("udp6", JoinHostPort(lla+"%"+ifi.Name, "0"))
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer c1.Close()
+	c2, err := ListenPacket("udp6", JoinHostPort(lla+"%"+ifi.Name, "0"))
+	if err != nil {
+		b.Fatal(err)
+	}
+	defer c2.Close()
+
+	var buf [1]byte
+	for i := 0; i < b.N; i++ {
+		if _, err := c1.WriteTo(buf[:], c2.LocalAddr()); err != nil {
+			b.Fatal(err)
+		}
+		if _, _, err := c2.ReadFrom(buf[:]); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
 type resolveUDPAddrTest struct {
 	network       string
 	litAddrOrName string
@@ -178,9 +216,7 @@ var udpConnLocalNameTests = []struct {
 }
 
 func TestUDPConnLocalName(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	for _, tt := range udpConnLocalNameTests {
 		c, err := ListenUDP(tt.net, tt.laddr)
@@ -234,9 +270,8 @@ func TestUDPConnLocalAndRemoteNames(t *testing.T) {
 }
 
 func TestIPv6LinkLocalUnicastUDP(t *testing.T) {
-	if testing.Short() || !*testExternal {
-		t.Skip("avoid external network")
-	}
+	testenv.MustHaveExternalNetwork(t)
+
 	if !supportsIPv6 {
 		t.Skip("IPv6 is not supported")
 	}
@@ -356,7 +391,7 @@ func TestUDPZeroByteBuffer(t *testing.T) {
 		switch err {
 		case nil: // ReadFrom succeeds
 		default: // Read may timeout, it depends on the platform
-			if nerr, ok := err.(Error); (!ok || !nerr.Timeout()) && runtime.GOOS != "windows" { // Windows retruns WSAEMSGSIZ
+			if nerr, ok := err.(Error); (!ok || !nerr.Timeout()) && runtime.GOOS != "windows" { // Windows returns WSAEMSGSIZ
 				t.Fatal(err)
 			}
 		}
diff --git a/libgo/go/net/unixsock.go b/libgo/go/net/unixsock.go
index eb91d0d6309..bacdaa41d90 100644
--- a/libgo/go/net/unixsock.go
+++ b/libgo/go/net/unixsock.go
@@ -1,9 +1,16 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
+import (
+	"context"
+	"os"
+	"syscall"
+	"time"
+)
+
 // UnixAddr represents the address of a Unix domain socket end point.
 type UnixAddr struct {
 	Name string
@@ -45,3 +52,268 @@ func ResolveUnixAddr(net, addr string) (*UnixAddr, error) {
 		return nil, UnknownNetworkError(net)
 	}
 }
+
+// UnixConn is an implementation of the Conn interface for connections
+// to Unix domain sockets.
+type UnixConn struct {
+	conn
+}
+
+// CloseRead shuts down the reading side of the Unix domain connection.
+// Most callers should just use Close.
+func (c *UnixConn) CloseRead() error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := c.fd.closeRead(); err != nil {
+		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// CloseWrite shuts down the writing side of the Unix domain connection.
+// Most callers should just use Close.
+func (c *UnixConn) CloseWrite() error {
+	if !c.ok() {
+		return syscall.EINVAL
+	}
+	if err := c.fd.closeWrite(); err != nil {
+		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return nil
+}
+
+// ReadFromUnix reads a packet from c, copying the payload into b. It
+// returns the number of bytes copied into b and the source address of
+// the packet.
+//
+// ReadFromUnix can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetReadDeadline.
+func (c *UnixConn) ReadFromUnix(b []byte) (int, *UnixAddr, error) {
+	if !c.ok() {
+		return 0, nil, syscall.EINVAL
+	}
+	n, addr, err := c.readFrom(b)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return n, addr, err
+}
+
+// ReadFrom implements the PacketConn ReadFrom method.
+func (c *UnixConn) ReadFrom(b []byte) (int, Addr, error) {
+	if !c.ok() {
+		return 0, nil, syscall.EINVAL
+	}
+	n, addr, err := c.readFrom(b)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	if addr == nil {
+		return n, nil, err
+	}
+	return n, addr, err
+}
+
+// ReadMsgUnix reads a packet from c, copying the payload into b and
+// the associated out-of-band data into oob. It returns the number of
+// bytes copied into b, the number of bytes copied into oob, the flags
+// that were set on the packet, and the source address of the packet.
+func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
+	if !c.ok() {
+		return 0, 0, 0, nil, syscall.EINVAL
+	}
+	n, oobn, flags, addr, err = c.readMsg(b, oob)
+	if err != nil {
+		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
+	}
+	return
+}
+
+// WriteToUnix writes a packet to addr via c, copying the payload from b.
+//
+// WriteToUnix can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetWriteDeadline. On packet-oriented connections, write timeouts
+// are rare.
+func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	n, err := c.writeTo(b, addr)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	}
+	return n, err
+}
+
+// WriteTo implements the PacketConn WriteTo method.
+func (c *UnixConn) WriteTo(b []byte, addr Addr) (int, error) {
+	if !c.ok() {
+		return 0, syscall.EINVAL
+	}
+	a, ok := addr.(*UnixAddr)
+	if !ok {
+		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
+	}
+	n, err := c.writeTo(b, a)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
+	}
+	return n, err
+}
+
+// WriteMsgUnix writes a packet to addr via c, copying the payload
+// from b and the associated out-of-band data from oob. It returns
+// the number of payload and out-of-band bytes written.
+func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
+	if !c.ok() {
+		return 0, 0, syscall.EINVAL
+	}
+	n, oobn, err = c.writeMsg(b, oob, addr)
+	if err != nil {
+		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
+	}
+	return
+}
+
+func newUnixConn(fd *netFD) *UnixConn { return &UnixConn{conn{fd}} }
+
+// DialUnix connects to the remote address raddr on the network net,
+// which must be "unix", "unixgram" or "unixpacket".  If laddr is not
+// nil, it is used as the local address for the connection.
+func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
+	switch net {
+	case "unix", "unixgram", "unixpacket":
+	default:
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	c, err := dialUnix(context.Background(), net, laddr, raddr)
+	if err != nil {
+		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
+
+// UnixListener is a Unix domain socket listener. Clients should
+// typically use variables of type Listener instead of assuming Unix
+// domain sockets.
+type UnixListener struct {
+	fd     *netFD
+	path   string
+	unlink bool
+}
+
+func (ln *UnixListener) ok() bool { return ln != nil && ln.fd != nil }
+
+// AcceptUnix accepts the next incoming call and returns the new
+// connection.
+func (l *UnixListener) AcceptUnix() (*UnixConn, error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	c, err := l.accept()
+	if err != nil {
+		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return c, nil
+}
+
+// Accept implements the Accept method in the Listener interface.
+// Returned connections will be of type *UnixConn.
+func (l *UnixListener) Accept() (Conn, error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	c, err := l.accept()
+	if err != nil {
+		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return c, nil
+}
+
+// Close stops listening on the Unix address. Already accepted
+// connections are not closed.
+func (l *UnixListener) Close() error {
+	if !l.ok() {
+		return syscall.EINVAL
+	}
+	if err := l.close(); err != nil {
+		return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return nil
+}
+
+// Addr returns the listener's network address.
+// The Addr returned is shared by all invocations of Addr, so
+// do not modify it.
+func (l *UnixListener) Addr() Addr { return l.fd.laddr }
+
+// SetDeadline sets the deadline associated with the listener.
+// A zero time value disables the deadline.
+func (l *UnixListener) SetDeadline(t time.Time) error {
+	if !l.ok() {
+		return syscall.EINVAL
+	}
+	if err := l.fd.setDeadline(t); err != nil {
+		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return nil
+}
+
+// File returns a copy of the underlying os.File, set to blocking
+// mode. It is the caller's responsibility to close f when finished.
+// Closing l does not affect f, and closing f does not affect l.
+//
+// The returned os.File's file descriptor is different from the
+// connection's. Attempting to change properties of the original
+// using this duplicate may or may not have the desired effect.
+func (l *UnixListener) File() (f *os.File, err error) {
+	if !l.ok() {
+		return nil, syscall.EINVAL
+	}
+	f, err = l.file()
+	if err != nil {
+		err = &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+	}
+	return
+}
+
+// ListenUnix announces on the Unix domain socket laddr and returns a
+// Unix listener. The network net must be "unix" or "unixpacket".
+func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
+	switch net {
+	case "unix", "unixpacket":
+	default:
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if laddr == nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: errMissingAddress}
+	}
+	ln, err := listenUnix(context.Background(), net, laddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
+	}
+	return ln, nil
+}
+
+// ListenUnixgram listens for incoming Unix datagram packets addressed
+// to the local address laddr. The network net must be "unixgram".
+// The returned connection's ReadFrom and WriteTo methods can be used
+// to receive and send packets with per-packet addressing.
+func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
+	switch net {
+	case "unixgram":
+	default:
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
+	}
+	if laddr == nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: errMissingAddress}
+	}
+	c, err := listenUnixgram(context.Background(), net, laddr)
+	if err != nil {
+		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
+	}
+	return c, nil
+}
diff --git a/libgo/go/net/unixsock_plan9.go b/libgo/go/net/unixsock_plan9.go
index 84b6b600f66..e70eb211bbf 100644
--- a/libgo/go/net/unixsock_plan9.go
+++ b/libgo/go/net/unixsock_plan9.go
@@ -1,147 +1,51 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package net
 
 import (
+	"context"
 	"os"
 	"syscall"
-	"time"
 )
 
-// UnixConn is an implementation of the Conn interface for connections
-// to Unix domain sockets.
-type UnixConn struct {
-	conn
+func (c *UnixConn) readFrom(b []byte) (int, *UnixAddr, error) {
+	return 0, nil, syscall.EPLAN9
 }
 
-// ReadFromUnix reads a packet from c, copying the payload into b.  It
-// returns the number of bytes copied into b and the source address of
-// the packet.
-//
-// ReadFromUnix can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetReadDeadline.
-func (c *UnixConn) ReadFromUnix(b []byte) (int, *UnixAddr, error) {
-	return 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (c *UnixConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
+	return 0, 0, 0, nil, syscall.EPLAN9
 }
 
-// ReadFrom implements the PacketConn ReadFrom method.
-func (c *UnixConn) ReadFrom(b []byte) (int, Addr, error) {
-	return 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (c *UnixConn) writeTo(b []byte, addr *UnixAddr) (int, error) {
+	return 0, syscall.EPLAN9
 }
 
-// ReadMsgUnix reads a packet from c, copying the payload into b and
-// the associated out-of-band data into oob.  It returns the number of
-// bytes copied into b, the number of bytes copied into oob, the flags
-// that were set on the packet, and the source address of the packet.
-func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
-	return 0, 0, 0, nil, &OpError{Op: "read", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (c *UnixConn) writeMsg(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
+	return 0, 0, syscall.EPLAN9
 }
 
-// WriteToUnix writes a packet to addr via c, copying the payload from b.
-//
-// WriteToUnix can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetWriteDeadline.  On packet-oriented connections, write timeouts
-// are rare.
-func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (int, error) {
-	return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EPLAN9}
+func dialUnix(ctx context.Context, network string, laddr, raddr *UnixAddr) (*UnixConn, error) {
+	return nil, syscall.EPLAN9
 }
 
-// WriteTo implements the PacketConn WriteTo method.
-func (c *UnixConn) WriteTo(b []byte, addr Addr) (int, error) {
-	return 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr, Err: syscall.EPLAN9}
+func (ln *UnixListener) accept() (*UnixConn, error) {
+	return nil, syscall.EPLAN9
 }
 
-// WriteMsgUnix writes a packet to addr via c, copying the payload
-// from b and the associated out-of-band data from oob.  It returns
-// the number of payload and out-of-band bytes written.
-func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
-	return 0, 0, &OpError{Op: "write", Net: c.fd.dir, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EPLAN9}
+func (ln *UnixListener) close() error {
+	return syscall.EPLAN9
 }
 
-// CloseRead shuts down the reading side of the Unix domain connection.
-// Most callers should just use Close.
-func (c *UnixConn) CloseRead() error {
-	return &OpError{Op: "close", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func (ln *UnixListener) file() (*os.File, error) {
+	return nil, syscall.EPLAN9
 }
 
-// CloseWrite shuts down the writing side of the Unix domain connection.
-// Most callers should just use Close.
-func (c *UnixConn) CloseWrite() error {
-	return &OpError{Op: "close", Net: c.fd.dir, Source: c.fd.laddr, Addr: c.fd.raddr, Err: syscall.EPLAN9}
+func listenUnix(ctx context.Context, network string, laddr *UnixAddr) (*UnixListener, error) {
+	return nil, syscall.EPLAN9
 }
 
-// DialUnix connects to the remote address raddr on the network net,
-// which must be "unix", "unixgram" or "unixpacket".  If laddr is not
-// nil, it is used as the local address for the connection.
-func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
-	return dialUnix(net, laddr, raddr, noDeadline)
-}
-
-func dialUnix(net string, laddr, raddr *UnixAddr, deadline time.Time) (*UnixConn, error) {
-	return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: syscall.EPLAN9}
-}
-
-// UnixListener is a Unix domain socket listener.  Clients should
-// typically use variables of type Listener instead of assuming Unix
-// domain sockets.
-type UnixListener struct {
-	fd *netFD
-}
-
-// ListenUnix announces on the Unix domain socket laddr and returns a
-// Unix listener.  The network net must be "unix" or "unixpacket".
-func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
-	return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: syscall.EPLAN9}
-}
-
-// AcceptUnix accepts the next incoming call and returns the new
-// connection.
-func (l *UnixListener) AcceptUnix() (*UnixConn, error) {
-	return nil, &OpError{Op: "accept", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: syscall.EPLAN9}
-}
-
-// Accept implements the Accept method in the Listener interface; it
-// waits for the next call and returns a generic Conn.
-func (l *UnixListener) Accept() (Conn, error) {
-	return nil, &OpError{Op: "accept", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: syscall.EPLAN9}
-}
-
-// Close stops listening on the Unix address.  Already accepted
-// connections are not closed.
-func (l *UnixListener) Close() error {
-	return &OpError{Op: "close", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: syscall.EPLAN9}
-}
-
-// Addr returns the listener's network address.
-// The Addr returned is shared by all invocations of Addr, so
-// do not modify it.
-func (l *UnixListener) Addr() Addr { return nil }
-
-// SetDeadline sets the deadline associated with the listener.
-// A zero time value disables the deadline.
-func (l *UnixListener) SetDeadline(t time.Time) error {
-	return &OpError{Op: "set", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: syscall.EPLAN9}
-}
-
-// File returns a copy of the underlying os.File, set to blocking
-// mode.  It is the caller's responsibility to close f when finished.
-// Closing l does not affect f, and closing f does not affect l.
-//
-// The returned os.File's file descriptor is different from the
-// connection's.  Attempting to change properties of the original
-// using this duplicate may or may not have the desired effect.
-func (l *UnixListener) File() (*os.File, error) {
-	return nil, &OpError{Op: "file", Net: l.fd.dir, Source: nil, Addr: l.fd.laddr, Err: syscall.EPLAN9}
-}
-
-// ListenUnixgram listens for incoming Unix datagram packets addressed
-// to the local address laddr.  The network net must be "unixgram".
-// The returned connection's ReadFrom and WriteTo methods can be used
-// to receive and send packets with per-packet addressing.
-func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
-	return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: syscall.EPLAN9}
+func listenUnixgram(ctx context.Context, network string, laddr *UnixAddr) (*UnixConn, error) {
+	return nil, syscall.EPLAN9
 }
diff --git a/libgo/go/net/unixsock_posix.go b/libgo/go/net/unixsock_posix.go
index fb2397e26f2..5f0999c4c27 100644
--- a/libgo/go/net/unixsock_posix.go
+++ b/libgo/go/net/unixsock_posix.go
@@ -1,4 +1,4 @@
-// Copyright 2009 The Go Authors.  All rights reserved.
+// Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,13 +7,13 @@
 package net
 
 import (
+	"context"
 	"errors"
 	"os"
 	"syscall"
-	"time"
 )
 
-func unixSocket(net string, laddr, raddr sockaddr, mode string, deadline time.Time) (*netFD, error) {
+func unixSocket(ctx context.Context, net string, laddr, raddr sockaddr, mode string) (*netFD, error) {
 	var sotype int
 	switch net {
 	case "unix":
@@ -42,7 +42,7 @@ func unixSocket(net string, laddr, raddr sockaddr, mode string, deadline time.Ti
 		return nil, errors.New("unknown mode: " + mode)
 	}
 
-	fd, err := socket(net, syscall.AF_UNIX, sotype, 0, false, laddr, raddr, deadline, noCancel)
+	fd, err := socket(ctx, net, syscall.AF_UNIX, sotype, 0, false, laddr, raddr)
 	if err != nil {
 		return nil, err
 	}
@@ -94,25 +94,7 @@ func (a *UnixAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return &syscall.SockaddrUnix{Name: a.Name}, nil
 }
 
-// UnixConn is an implementation of the Conn interface for connections
-// to Unix domain sockets.
-type UnixConn struct {
-	conn
-}
-
-func newUnixConn(fd *netFD) *UnixConn { return &UnixConn{conn{fd}} }
-
-// ReadFromUnix reads a packet from c, copying the payload into b.  It
-// returns the number of bytes copied into b and the source address of
-// the packet.
-//
-// ReadFromUnix can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetReadDeadline.
-func (c *UnixConn) ReadFromUnix(b []byte) (int, *UnixAddr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
+func (c *UnixConn) readFrom(b []byte) (int, *UnixAddr, error) {
 	var addr *UnixAddr
 	n, sa, err := c.fd.readFrom(b)
 	switch sa := sa.(type) {
@@ -121,211 +103,66 @@ func (c *UnixConn) ReadFromUnix(b []byte) (int, *UnixAddr, error) {
 			addr = &UnixAddr{Name: sa.Name, Net: sotypeToNet(c.fd.sotype)}
 		}
 	}
-	if err != nil {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return n, addr, err
-}
-
-// ReadFrom implements the PacketConn ReadFrom method.
-func (c *UnixConn) ReadFrom(b []byte) (int, Addr, error) {
-	if !c.ok() {
-		return 0, nil, syscall.EINVAL
-	}
-	n, addr, err := c.ReadFromUnix(b)
-	if addr == nil {
-		return n, nil, err
-	}
 	return n, addr, err
 }
 
-// ReadMsgUnix reads a packet from c, copying the payload into b and
-// the associated out-of-band data into oob.  It returns the number of
-// bytes copied into b, the number of bytes copied into oob, the flags
-// that were set on the packet, and the source address of the packet.
-func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
-	if !c.ok() {
-		return 0, 0, 0, nil, syscall.EINVAL
-	}
-	n, oobn, flags, sa, err := c.fd.readMsg(b, oob)
+func (c *UnixConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
+	var sa syscall.Sockaddr
+	n, oobn, flags, sa, err = c.fd.readMsg(b, oob)
 	switch sa := sa.(type) {
 	case *syscall.SockaddrUnix:
 		if sa.Name != "" {
 			addr = &UnixAddr{Name: sa.Name, Net: sotypeToNet(c.fd.sotype)}
 		}
 	}
-	if err != nil {
-		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
 	return
 }
 
-// WriteToUnix writes a packet to addr via c, copying the payload from b.
-//
-// WriteToUnix can be made to time out and return an error with
-// Timeout() == true after a fixed time limit; see SetDeadline and
-// SetWriteDeadline.  On packet-oriented connections, write timeouts
-// are rare.
-func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (int, error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
+func (c *UnixConn) writeTo(b []byte, addr *UnixAddr) (int, error) {
 	if c.fd.isConnected {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
+		return 0, ErrWriteToConnected
 	}
 	if addr == nil {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
+		return 0, errMissingAddress
 	}
 	if addr.Net != sotypeToNet(c.fd.sotype) {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EAFNOSUPPORT}
+		return 0, syscall.EAFNOSUPPORT
 	}
 	sa := &syscall.SockaddrUnix{Name: addr.Name}
-	n, err := c.fd.writeTo(b, sa)
-	if err != nil {
-		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
-	}
-	return n, err
-}
-
-// WriteTo implements the PacketConn WriteTo method.
-func (c *UnixConn) WriteTo(b []byte, addr Addr) (n int, err error) {
-	if !c.ok() {
-		return 0, syscall.EINVAL
-	}
-	a, ok := addr.(*UnixAddr)
-	if !ok {
-		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
-	}
-	return c.WriteToUnix(b, a)
+	return c.fd.writeTo(b, sa)
 }
 
-// WriteMsgUnix writes a packet to addr via c, copying the payload
-// from b and the associated out-of-band data from oob.  It returns
-// the number of payload and out-of-band bytes written.
-func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
-	if !c.ok() {
-		return 0, 0, syscall.EINVAL
-	}
+func (c *UnixConn) writeMsg(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
 	if c.fd.sotype == syscall.SOCK_DGRAM && c.fd.isConnected {
-		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
+		return 0, 0, ErrWriteToConnected
 	}
 	var sa syscall.Sockaddr
 	if addr != nil {
 		if addr.Net != sotypeToNet(c.fd.sotype) {
-			return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: syscall.EAFNOSUPPORT}
+			return 0, 0, syscall.EAFNOSUPPORT
 		}
 		sa = &syscall.SockaddrUnix{Name: addr.Name}
 	}
-	n, oobn, err = c.fd.writeMsg(b, oob, sa)
-	if err != nil {
-		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
-	}
-	return
-}
-
-// CloseRead shuts down the reading side of the Unix domain connection.
-// Most callers should just use Close.
-func (c *UnixConn) CloseRead() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeRead()
-	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
+	return c.fd.writeMsg(b, oob, sa)
 }
 
-// CloseWrite shuts down the writing side of the Unix domain connection.
-// Most callers should just use Close.
-func (c *UnixConn) CloseWrite() error {
-	if !c.ok() {
-		return syscall.EINVAL
-	}
-	err := c.fd.closeWrite()
+func dialUnix(ctx context.Context, net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
+	fd, err := unixSocket(ctx, net, laddr, raddr, "dial")
 	if err != nil {
-		err = &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
-	}
-	return err
-}
-
-// DialUnix connects to the remote address raddr on the network net,
-// which must be "unix", "unixgram" or "unixpacket".  If laddr is not
-// nil, it is used as the local address for the connection.
-func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
-	switch net {
-	case "unix", "unixgram", "unixpacket":
-	default:
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	return dialUnix(net, laddr, raddr, noDeadline)
-}
-
-func dialUnix(net string, laddr, raddr *UnixAddr, deadline time.Time) (*UnixConn, error) {
-	fd, err := unixSocket(net, laddr, raddr, "dial", deadline)
-	if err != nil {
-		return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
-	}
-	return newUnixConn(fd), nil
-}
-
-// UnixListener is a Unix domain socket listener.  Clients should
-// typically use variables of type Listener instead of assuming Unix
-// domain sockets.
-type UnixListener struct {
-	fd     *netFD
-	path   string
-	unlink bool
-}
-
-// ListenUnix announces on the Unix domain socket laddr and returns a
-// Unix listener.  The network net must be "unix" or "unixpacket".
-func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
-	switch net {
-	case "unix", "unixpacket":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: errMissingAddress}
-	}
-	fd, err := unixSocket(net, laddr, nil, "listen", noDeadline)
-	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
-	}
-	return &UnixListener{fd: fd, path: fd.laddr.String(), unlink: true}, nil
-}
-
-// AcceptUnix accepts the next incoming call and returns the new
-// connection.
-func (l *UnixListener) AcceptUnix() (*UnixConn, error) {
-	if l == nil || l.fd == nil {
-		return nil, syscall.EINVAL
-	}
-	fd, err := l.fd.accept()
-	if err != nil {
-		return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+		return nil, err
 	}
 	return newUnixConn(fd), nil
 }
 
-// Accept implements the Accept method in the Listener interface; it
-// waits for the next call and returns a generic Conn.
-func (l *UnixListener) Accept() (c Conn, err error) {
-	c1, err := l.AcceptUnix()
+func (ln *UnixListener) accept() (*UnixConn, error) {
+	fd, err := ln.fd.accept()
 	if err != nil {
 		return nil, err
 	}
-	return c1, nil
+	return newUnixConn(fd), nil
 }
 
-// Close stops listening on the Unix address.  Already accepted
-// connections are not closed.
-func (l *UnixListener) Close() error {
-	if l == nil || l.fd == nil {
-		return syscall.EINVAL
-	}
-
+func (ln *UnixListener) close() error {
 	// The operating system doesn't clean up
 	// the file that announcing created, so
 	// we have to clean it up ourselves.
@@ -334,66 +171,34 @@ func (l *UnixListener) Close() error {
 	// and replaced our socket name already--
 	// but this sequence (remove then close)
 	// is at least compatible with the auto-remove
-	// sequence in ListenUnix.  It's only non-Go
+	// sequence in ListenUnix. It's only non-Go
 	// programs that can mess us up.
-	if l.path[0] != '@' && l.unlink {
-		syscall.Unlink(l.path)
-	}
-	err := l.fd.Close()
-	if err != nil {
-		err = &OpError{Op: "close", Net: l.fd.net, Source: l.fd.laddr, Addr: l.fd.raddr, Err: err}
+	if ln.path[0] != '@' && ln.unlink {
+		syscall.Unlink(ln.path)
 	}
-	return err
+	return ln.fd.Close()
 }
 
-// Addr returns the listener's network address.
-// The Addr returned is shared by all invocations of Addr, so
-// do not modify it.
-func (l *UnixListener) Addr() Addr { return l.fd.laddr }
-
-// SetDeadline sets the deadline associated with the listener.
-// A zero time value disables the deadline.
-func (l *UnixListener) SetDeadline(t time.Time) error {
-	if l == nil || l.fd == nil {
-		return syscall.EINVAL
-	}
-	if err := l.fd.setDeadline(t); err != nil {
-		return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+func (ln *UnixListener) file() (*os.File, error) {
+	f, err := ln.fd.dup()
+	if err != nil {
+		return nil, err
 	}
-	return nil
+	return f, nil
 }
 
-// File returns a copy of the underlying os.File, set to blocking
-// mode.  It is the caller's responsibility to close f when finished.
-// Closing l does not affect f, and closing f does not affect l.
-//
-// The returned os.File's file descriptor is different from the
-// connection's.  Attempting to change properties of the original
-// using this duplicate may or may not have the desired effect.
-func (l *UnixListener) File() (f *os.File, err error) {
-	f, err = l.fd.dup()
+func listenUnix(ctx context.Context, network string, laddr *UnixAddr) (*UnixListener, error) {
+	fd, err := unixSocket(ctx, network, laddr, nil, "listen")
 	if err != nil {
-		err = &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err}
+		return nil, err
 	}
-	return
+	return &UnixListener{fd: fd, path: fd.laddr.String(), unlink: true}, nil
 }
 
-// ListenUnixgram listens for incoming Unix datagram packets addressed
-// to the local address laddr.  The network net must be "unixgram".
-// The returned connection's ReadFrom and WriteTo methods can be used
-// to receive and send packets with per-packet addressing.
-func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
-	switch net {
-	case "unixgram":
-	default:
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)}
-	}
-	if laddr == nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: errMissingAddress}
-	}
-	fd, err := unixSocket(net, laddr, nil, "listen", noDeadline)
+func listenUnixgram(ctx context.Context, network string, laddr *UnixAddr) (*UnixConn, error) {
+	fd, err := unixSocket(ctx, network, laddr, nil, "listen")
 	if err != nil {
-		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err}
+		return nil, err
 	}
 	return newUnixConn(fd), nil
 }
diff --git a/libgo/go/net/unix_test.go b/libgo/go/net/unixsock_test.go
index f0c583068ec..f0f88ed37b2 100644
--- a/libgo/go/net/unix_test.go
+++ b/libgo/go/net/unixsock_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,6 +8,7 @@ package net
 
 import (
 	"bytes"
+	"internal/testenv"
 	"os"
 	"reflect"
 	"runtime"
@@ -20,6 +21,9 @@ func TestReadUnixgramWithUnnamedSocket(t *testing.T) {
 	if !testableNetwork("unixgram") {
 		t.Skip("unixgram test")
 	}
+	if runtime.GOOS == "openbsd" {
+		testenv.SkipFlaky(t, 15157)
+	}
 
 	addr := testUnixAddr()
 	la, err := ResolveUnixAddr("unixgram", addr)
@@ -440,34 +444,3 @@ func TestUnixUnlink(t *testing.T) {
 		t.Fatal("closing unix listener did not remove unix socket")
 	}
 }
-
-// forceGoDNS forces the resolver configuration to use the pure Go resolver
-// and returns a fixup function to restore the old settings.
-func forceGoDNS() func() {
-	c := systemConf()
-	oldGo := c.netGo
-	oldCgo := c.netCgo
-	fixup := func() {
-		c.netGo = oldGo
-		c.netCgo = oldCgo
-	}
-	c.netGo = true
-	c.netCgo = false
-	return fixup
-}
-
-// forceCgoDNS forces the resolver configuration to use the cgo resolver
-// and returns a fixup function to restore the old settings.
-// (On non-Unix systems forceCgoDNS returns nil.)
-func forceCgoDNS() func() {
-	c := systemConf()
-	oldGo := c.netGo
-	oldCgo := c.netCgo
-	fixup := func() {
-		c.netGo = oldGo
-		c.netCgo = oldCgo
-	}
-	c.netGo = false
-	c.netCgo = true
-	return fixup
-}
diff --git a/libgo/go/net/url/url.go b/libgo/go/net/url/url.go
index 1a93e3496ed..30e92779370 100644
--- a/libgo/go/net/url/url.go
+++ b/libgo/go/net/url/url.go
@@ -3,9 +3,13 @@
 // license that can be found in the LICENSE file.
 
 // Package url parses URLs and implements query escaping.
-// See RFC 3986.
 package url
 
+// See RFC 3986. This package generally follows RFC 3986, except where
+// it deviates for compatibility reasons. When sending changes, first
+// search old issues for history on decisions. Unit tests should also
+// contain references to issue numbers with details.
+
 import (
 	"bytes"
 	"errors"
@@ -307,14 +311,15 @@ func escape(s string, mode encoding) string {
 // construct a URL struct directly and set the Opaque field instead of Path.
 // These still work as well.
 type URL struct {
-	Scheme   string
-	Opaque   string    // encoded opaque data
-	User     *Userinfo // username and password information
-	Host     string    // host or host:port
-	Path     string
-	RawPath  string // encoded path hint (Go 1.5 and later only; see EscapedPath method)
-	RawQuery string // encoded query values, without '?'
-	Fragment string // fragment for references, without '#'
+	Scheme     string
+	Opaque     string    // encoded opaque data
+	User       *Userinfo // username and password information
+	Host       string    // host or host:port
+	Path       string
+	RawPath    string // encoded path hint (Go 1.5 and later only; see EscapedPath method)
+	ForceQuery bool   // append a query ('?') even if RawQuery is empty
+	RawQuery   string // encoded query values, without '?'
+	Fragment   string // fragment for references, without '#'
 }
 
 // User returns a Userinfo containing the provided username
@@ -410,10 +415,11 @@ func split(s string, c string, cutc bool) (string, string) {
 
 // Parse parses rawurl into a URL structure.
 // The rawurl may be relative or absolute.
-func Parse(rawurl string) (url *URL, err error) {
+func Parse(rawurl string) (*URL, error) {
 	// Cut off #frag
 	u, frag := split(rawurl, "#", true)
-	if url, err = parse(u, false); err != nil {
+	url, err := parse(u, false)
+	if err != nil {
 		return nil, err
 	}
 	if frag == "" {
@@ -425,16 +431,16 @@ func Parse(rawurl string) (url *URL, err error) {
 	return url, nil
 }
 
-// ParseRequestURI parses rawurl into a URL structure.  It assumes that
+// ParseRequestURI parses rawurl into a URL structure. It assumes that
 // rawurl was received in an HTTP request, so the rawurl is interpreted
 // only as an absolute URI or an absolute path.
 // The string rawurl is assumed not to have a #fragment suffix.
 // (Web browsers strip #fragment before sending the URL to a web server.)
-func ParseRequestURI(rawurl string) (url *URL, err error) {
+func ParseRequestURI(rawurl string) (*URL, error) {
 	return parse(rawurl, true)
 }
 
-// parse parses a URL from a string in one of two contexts.  If
+// parse parses a URL from a string in one of two contexts. If
 // viaRequest is true, the URL is assumed to have arrived via an HTTP request,
 // in which case only absolute URLs or path-absolute relative URLs are allowed.
 // If viaRequest is false, all forms of relative URLs are allowed.
@@ -459,7 +465,12 @@ func parse(rawurl string, viaRequest bool) (url *URL, err error) {
 	}
 	url.Scheme = strings.ToLower(url.Scheme)
 
-	rest, url.RawQuery = split(rest, "?", true)
+	if strings.HasSuffix(rest, "?") && strings.Count(rest, "?") == 1 {
+		url.ForceQuery = true
+		rest = rest[:len(rest)-1]
+	} else {
+		rest, url.RawQuery = split(rest, "?", true)
+	}
 
 	if !strings.HasPrefix(rest, "/") {
 		if url.Scheme != "" {
@@ -511,7 +522,7 @@ func parseAuthority(authority string) (user *Userinfo, host string, err error) {
 		return nil, host, nil
 	}
 	userinfo := authority[:i]
-	if strings.Index(userinfo, ":") < 0 {
+	if !strings.Contains(userinfo, ":") {
 		if userinfo, err = unescape(userinfo, encodeUserPassword); err != nil {
 			return nil, "", err
 		}
@@ -684,7 +695,7 @@ func (u *URL) String() string {
 		}
 		buf.WriteString(path)
 	}
-	if u.RawQuery != "" {
+	if u.ForceQuery || u.RawQuery != "" {
 		buf.WriteByte('?')
 		buf.WriteString(u.RawQuery)
 	}
@@ -709,8 +720,8 @@ func (v Values) Get(key string) string {
 	if v == nil {
 		return ""
 	}
-	vs, ok := v[key]
-	if !ok || len(vs) == 0 {
+	vs := v[key]
+	if len(vs) == 0 {
 		return ""
 	}
 	return vs[0]
@@ -738,10 +749,10 @@ func (v Values) Del(key string) {
 // ParseQuery always returns a non-nil map containing all the
 // valid query parameters found; err describes the first decoding error
 // encountered, if any.
-func ParseQuery(query string) (m Values, err error) {
-	m = make(Values)
-	err = parseQuery(m, query)
-	return
+func ParseQuery(query string) (Values, error) {
+	m := make(Values)
+	err := parseQuery(m, query)
+	return m, err
 }
 
 func parseQuery(m Values, query string) (err error) {
@@ -845,8 +856,8 @@ func (u *URL) IsAbs() bool {
 	return u.Scheme != ""
 }
 
-// Parse parses a URL in the context of the receiver.  The provided URL
-// may be relative or absolute.  Parse returns nil, err on parse
+// Parse parses a URL in the context of the receiver. The provided URL
+// may be relative or absolute. Parse returns nil, err on parse
 // failure, otherwise its return value is the same as ResolveReference.
 func (u *URL) Parse(ref string) (*URL, error) {
 	refurl, err := Parse(ref)
@@ -858,7 +869,7 @@ func (u *URL) Parse(ref string) (*URL, error) {
 
 // ResolveReference resolves a URI reference to an absolute URI from
 // an absolute base URI, per RFC 3986 Section 5.2.  The URI reference
-// may be relative or absolute.  ResolveReference always returns a new
+// may be relative or absolute. ResolveReference always returns a new
 // URL instance, even if the returned URL is identical to either the
 // base or reference. If ref is an absolute URL, then ResolveReference
 // ignores base and returns a copy of ref.
@@ -913,7 +924,7 @@ func (u *URL) RequestURI() string {
 			result = u.Scheme + ":" + result
 		}
 	}
-	if u.RawQuery != "" {
+	if u.ForceQuery || u.RawQuery != "" {
 		result += "?" + u.RawQuery
 	}
 	return result
diff --git a/libgo/go/net/url/url_test.go b/libgo/go/net/url/url_test.go
index d3f8487bd7c..7560f22c4a1 100644
--- a/libgo/go/net/url/url_test.go
+++ b/libgo/go/net/url/url_test.go
@@ -72,6 +72,28 @@ var urltests = []URLTest{
 		},
 		"ftp://john%20doe@www.google.com/",
 	},
+	// empty query
+	{
+		"http://www.google.com/?",
+		&URL{
+			Scheme:     "http",
+			Host:       "www.google.com",
+			Path:       "/",
+			ForceQuery: true,
+		},
+		"",
+	},
+	// query ending in question mark (Issue 14573)
+	{
+		"http://www.google.com/?foo=bar?",
+		&URL{
+			Scheme:   "http",
+			Host:     "www.google.com",
+			Path:     "/",
+			RawQuery: "foo=bar?",
+		},
+		"",
+	},
 	// query
 	{
 		"http://www.google.com/?q=go+language",
@@ -553,8 +575,8 @@ func ufmt(u *URL) string {
 			pass = p
 		}
 	}
-	return fmt.Sprintf("opaque=%q, scheme=%q, user=%#v, pass=%#v, host=%q, path=%q, rawpath=%q, rawq=%q, frag=%q",
-		u.Opaque, u.Scheme, user, pass, u.Host, u.Path, u.RawPath, u.RawQuery, u.Fragment)
+	return fmt.Sprintf("opaque=%q, scheme=%q, user=%#v, pass=%#v, host=%q, path=%q, rawpath=%q, rawq=%q, frag=%q, forcequery=%v",
+		u.Opaque, u.Scheme, user, pass, u.Host, u.Path, u.RawPath, u.RawQuery, u.Fragment, u.ForceQuery)
 }
 
 func DoTest(t *testing.T, parse func(string) (*URL, error), name string, tests []URLTest) {
@@ -589,7 +611,7 @@ func BenchmarkString(b *testing.B) {
 			g = u.String()
 		}
 		b.StopTimer()
-		if w := tt.roundtrip; g != w {
+		if w := tt.roundtrip; b.N > 0 && g != w {
 			b.Errorf("Parse(%q).String() == %q, want %q", tt.in, g, w)
 		}
 	}
@@ -874,11 +896,13 @@ var resolveReferenceTests = []struct {
 	// Absolute URL references
 	{"http://foo.com?a=b", "https://bar.com/", "https://bar.com/"},
 	{"http://foo.com/", "https://bar.com/?a=b", "https://bar.com/?a=b"},
+	{"http://foo.com/", "https://bar.com/?", "https://bar.com/?"},
 	{"http://foo.com/bar", "mailto:foo@example.com", "mailto:foo@example.com"},
 
 	// Path-absolute references
 	{"http://foo.com/bar", "/baz", "http://foo.com/baz"},
 	{"http://foo.com/bar?a=b#f", "/baz", "http://foo.com/baz"},
+	{"http://foo.com/bar?a=b", "/baz?", "http://foo.com/baz?"},
 	{"http://foo.com/bar?a=b", "/baz?c=d", "http://foo.com/baz?c=d"},
 
 	// Scheme-relative
@@ -1217,6 +1241,15 @@ var requritests = []RequestURITest{
 		},
 		"//foo",
 	},
+	{
+		&URL{
+			Scheme:     "http",
+			Host:       "example.com",
+			Path:       "/foo",
+			ForceQuery: true,
+		},
+		"/foo?",
+	},
 }
 
 func TestRequestURI(t *testing.T) {
diff --git a/libgo/go/os/doc.go b/libgo/go/os/doc.go
index 869a28a8a4e..0313eac234d 100644
--- a/libgo/go/os/doc.go
+++ b/libgo/go/os/doc.go
@@ -77,14 +77,14 @@ func (p *ProcessState) Success() bool {
 }
 
 // Sys returns system-dependent exit information about
-// the process.  Convert it to the appropriate underlying
+// the process. Convert it to the appropriate underlying
 // type, such as syscall.WaitStatus on Unix, to access its contents.
 func (p *ProcessState) Sys() interface{} {
 	return p.sys()
 }
 
 // SysUsage returns system-dependent resource usage information about
-// the exited process.  Convert it to the appropriate underlying
+// the exited process. Convert it to the appropriate underlying
 // type, such as *syscall.Rusage on Unix, to access its contents.
 // (On Unix, *syscall.Rusage matches struct rusage as defined in the
 // getrusage(2) manual page.)
@@ -112,7 +112,7 @@ func Hostname() (name string, err error) {
 // nil error. If it encounters an error before the end of the
 // directory, Readdir returns the FileInfo read until that point
 // and a non-nil error.
-func (f *File) Readdir(n int) (fi []FileInfo, err error) {
+func (f *File) Readdir(n int) ([]FileInfo, error) {
 	if f == nil {
 		return nil, ErrInvalid
 	}
diff --git a/libgo/go/os/env.go b/libgo/go/os/env.go
index a4ede15e613..4a147144c3e 100644
--- a/libgo/go/os/env.go
+++ b/libgo/go/os/env.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -27,7 +27,7 @@ func Expand(s string, mapping func(string) string) string {
 }
 
 // ExpandEnv replaces ${var} or $var in the string according to the values
-// of the current environment variables.  References to undefined
+// of the current environment variables. References to undefined
 // variables are replaced by the empty string.
 func ExpandEnv(s string) string {
 	return Expand(s, Getenv)
@@ -49,7 +49,7 @@ func isAlphaNum(c uint8) bool {
 }
 
 // getShellName returns the name that begins the string and the number of bytes
-// consumed to extract it.  If the name is enclosed in {}, it's part of a ${}
+// consumed to extract it. If the name is enclosed in {}, it's part of a ${}
 // expansion and two more bytes are needed than the length of the name.
 func getShellName(s string) (string, int) {
 	switch {
diff --git a/libgo/go/os/error_test.go b/libgo/go/os/error_test.go
index 5477e7ecbdb..a47c1732cb8 100644
--- a/libgo/go/os/error_test.go
+++ b/libgo/go/os/error_test.go
@@ -80,11 +80,13 @@ func checkErrorPredicate(predName string, pred func(error) bool, err error) stri
 	return ""
 }
 
-var isExistTests = []struct {
+type isExistTest struct {
 	err   error
 	is    bool
 	isnot bool
-}{
+}
+
+var isExistTests = []isExistTest{
 	{&os.PathError{Err: os.ErrInvalid}, false, false},
 	{&os.PathError{Err: os.ErrPermission}, false, false},
 	{&os.PathError{Err: os.ErrExist}, true, false},
@@ -109,10 +111,12 @@ func TestIsExist(t *testing.T) {
 	}
 }
 
-var isPermissionTests = []struct {
+type isPermissionTest struct {
 	err  error
 	want bool
-}{
+}
+
+var isPermissionTests = []isPermissionTest{
 	{nil, false},
 	{&os.PathError{Err: os.ErrPermission}, true},
 	{&os.SyscallError{Err: os.ErrPermission}, true},
diff --git a/libgo/go/os/error_unix.go b/libgo/go/os/error_unix.go
index c6002279da6..3c78eb4dd2f 100644
--- a/libgo/go/os/error_unix.go
+++ b/libgo/go/os/error_unix.go
@@ -19,7 +19,7 @@ func isExist(err error) bool {
 	case *SyscallError:
 		err = pe.Err
 	}
-	return err == syscall.EEXIST || err == ErrExist
+	return err == syscall.EEXIST || err == syscall.ENOTEMPTY || err == ErrExist
 }
 
 func isNotExist(err error) bool {
diff --git a/libgo/go/os/error_unix_test.go b/libgo/go/os/error_unix_test.go
new file mode 100644
index 00000000000..76fe015b221
--- /dev/null
+++ b/libgo/go/os/error_unix_test.go
@@ -0,0 +1,39 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+
+package os_test
+
+import (
+	"os"
+	"syscall"
+)
+
+func init() {
+	isExistTests = append(isExistTests,
+		isExistTest{err: &os.PathError{Err: syscall.EEXIST}, is: true, isnot: false},
+		isExistTest{err: &os.PathError{Err: syscall.ENOTEMPTY}, is: true, isnot: false},
+
+		isExistTest{err: &os.LinkError{Err: syscall.EEXIST}, is: true, isnot: false},
+		isExistTest{err: &os.LinkError{Err: syscall.ENOTEMPTY}, is: true, isnot: false},
+
+		isExistTest{err: &os.SyscallError{Err: syscall.EEXIST}, is: true, isnot: false},
+		isExistTest{err: &os.SyscallError{Err: syscall.ENOTEMPTY}, is: true, isnot: false},
+	)
+	isPermissionTests = append(isPermissionTests,
+		isPermissionTest{err: &os.PathError{Err: syscall.EACCES}, want: true},
+		isPermissionTest{err: &os.PathError{Err: syscall.EPERM}, want: true},
+		isPermissionTest{err: &os.PathError{Err: syscall.EEXIST}, want: false},
+
+		isPermissionTest{err: &os.LinkError{Err: syscall.EACCES}, want: true},
+		isPermissionTest{err: &os.LinkError{Err: syscall.EPERM}, want: true},
+		isPermissionTest{err: &os.LinkError{Err: syscall.EEXIST}, want: false},
+
+		isPermissionTest{err: &os.SyscallError{Err: syscall.EACCES}, want: true},
+		isPermissionTest{err: &os.SyscallError{Err: syscall.EPERM}, want: true},
+		isPermissionTest{err: &os.SyscallError{Err: syscall.EEXIST}, want: false},
+	)
+
+}
diff --git a/libgo/go/os/error_windows_test.go b/libgo/go/os/error_windows_test.go
new file mode 100644
index 00000000000..427dfdb962c
--- /dev/null
+++ b/libgo/go/os/error_windows_test.go
@@ -0,0 +1,35 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows
+
+package os_test
+
+import (
+	"os"
+	"syscall"
+)
+
+func init() {
+	const _ERROR_BAD_NETPATH = syscall.Errno(53)
+
+	isExistTests = append(isExistTests,
+		isExistTest{err: &os.PathError{Err: syscall.ERROR_FILE_NOT_FOUND}, is: false, isnot: true},
+		isExistTest{err: &os.LinkError{Err: syscall.ERROR_FILE_NOT_FOUND}, is: false, isnot: true},
+		isExistTest{err: &os.SyscallError{Err: syscall.ERROR_FILE_NOT_FOUND}, is: false, isnot: true},
+
+		isExistTest{err: &os.PathError{Err: _ERROR_BAD_NETPATH}, is: false, isnot: true},
+		isExistTest{err: &os.LinkError{Err: _ERROR_BAD_NETPATH}, is: false, isnot: true},
+		isExistTest{err: &os.SyscallError{Err: _ERROR_BAD_NETPATH}, is: false, isnot: true},
+
+		isExistTest{err: &os.PathError{Err: syscall.ERROR_PATH_NOT_FOUND}, is: false, isnot: true},
+		isExistTest{err: &os.LinkError{Err: syscall.ERROR_PATH_NOT_FOUND}, is: false, isnot: true},
+		isExistTest{err: &os.SyscallError{Err: syscall.ERROR_PATH_NOT_FOUND}, is: false, isnot: true},
+	)
+	isPermissionTests = append(isPermissionTests,
+		isPermissionTest{err: &os.PathError{Err: syscall.ERROR_ACCESS_DENIED}, want: true},
+		isPermissionTest{err: &os.LinkError{Err: syscall.ERROR_ACCESS_DENIED}, want: true},
+		isPermissionTest{err: &os.SyscallError{Err: syscall.ERROR_ACCESS_DENIED}, want: true},
+	)
+}
diff --git a/libgo/go/os/exec.go b/libgo/go/os/exec.go
index 15e95b91722..bf3249864d3 100644
--- a/libgo/go/os/exec.go
+++ b/libgo/go/os/exec.go
@@ -6,6 +6,7 @@ package os
 
 import (
 	"runtime"
+	"sync"
 	"sync/atomic"
 	"syscall"
 )
@@ -13,8 +14,9 @@ import (
 // Process stores the information about a process created by StartProcess.
 type Process struct {
 	Pid    int
-	handle uintptr // handle is accessed atomically on Windows
-	isdone uint32  // process has been successfully waited on, non zero if true
+	handle uintptr      // handle is accessed atomically on Windows
+	isdone uint32       // process has been successfully waited on, non zero if true
+	sigMu  sync.RWMutex // avoid race between wait and signal
 }
 
 func newProcess(pid int, handle uintptr) *Process {
@@ -41,10 +43,10 @@ type ProcAttr struct {
 	// new process in the form returned by Environ.
 	// If it is nil, the result of Environ will be used.
 	Env []string
-	// Files specifies the open files inherited by the new process.  The
+	// Files specifies the open files inherited by the new process. The
 	// first three entries correspond to standard input, standard output, and
-	// standard error.  An implementation may support additional entries,
-	// depending on the underlying operating system.  A nil entry corresponds
+	// standard error. An implementation may support additional entries,
+	// depending on the underlying operating system. A nil entry corresponds
 	// to that file being closed when the process starts.
 	Files []*File
 
diff --git a/libgo/go/os/exec/exec.go b/libgo/go/os/exec/exec.go
index 340ebd498b7..d2c1b17e509 100644
--- a/libgo/go/os/exec/exec.go
+++ b/libgo/go/os/exec/exec.go
@@ -13,6 +13,7 @@ package exec
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"io"
 	"os"
@@ -102,13 +103,15 @@ type Cmd struct {
 	// available after a call to Wait or Run.
 	ProcessState *os.ProcessState
 
-	lookPathErr     error // LookPath error, if any.
-	finished        bool  // when Wait was called
+	ctx             context.Context // nil means none
+	lookPathErr     error           // LookPath error, if any.
+	finished        bool            // when Wait was called
 	childFiles      []*os.File
 	closeAfterStart []io.Closer
 	closeAfterWait  []io.Closer
 	goroutine       []func() error
 	errch           chan error // one send per goroutine
+	waitDone        chan struct{}
 }
 
 // Command returns the Cmd struct to execute the named program with
@@ -138,6 +141,20 @@ func Command(name string, arg ...string) *Cmd {
 	return cmd
 }
 
+// CommandContext is like Command but includes a context.
+//
+// The provided context is used to kill the process (by calling
+// os.Process.Kill) if the context becomes done before the command
+// completes on its own.
+func CommandContext(ctx context.Context, name string, arg ...string) *Cmd {
+	if ctx == nil {
+		panic("nil Context")
+	}
+	cmd := Command(name, arg...)
+	cmd.ctx = ctx
+	return cmd
+}
+
 // interfaceEqual protects against panics from doing equality tests on
 // two interfaces with non-comparable underlying types.
 func interfaceEqual(a, b interface{}) bool {
@@ -310,6 +327,15 @@ func (c *Cmd) Start() error {
 	if c.Process != nil {
 		return errors.New("exec: already started")
 	}
+	if c.ctx != nil {
+		select {
+		case <-c.ctx.Done():
+			c.closeDescriptors(c.closeAfterStart)
+			c.closeDescriptors(c.closeAfterWait)
+			return c.ctx.Err()
+		default:
+		}
+	}
 
 	type F func(*Cmd) (*os.File, error)
 	for _, setupFd := range []F{(*Cmd).stdin, (*Cmd).stdout, (*Cmd).stderr} {
@@ -345,6 +371,17 @@ func (c *Cmd) Start() error {
 		}(fn)
 	}
 
+	if c.ctx != nil {
+		c.waitDone = make(chan struct{})
+		go func() {
+			select {
+			case <-c.ctx.Done():
+				c.Process.Kill()
+			case <-c.waitDone:
+			}
+		}()
+	}
+
 	return nil
 }
 
@@ -393,7 +430,11 @@ func (c *Cmd) Wait() error {
 		return errors.New("exec: Wait was already called")
 	}
 	c.finished = true
+
 	state, err := c.Process.Wait()
+	if c.waitDone != nil {
+		close(c.waitDone)
+	}
 	c.ProcessState = state
 
 	var copyError error
diff --git a/libgo/go/os/exec/exec_test.go b/libgo/go/os/exec/exec_test.go
index 1576e8f1567..3a866a99550 100644
--- a/libgo/go/os/exec/exec_test.go
+++ b/libgo/go/os/exec/exec_test.go
@@ -10,6 +10,7 @@ package exec_test
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"fmt"
 	"internal/testenv"
 	"io"
@@ -28,12 +29,16 @@ import (
 	"time"
 )
 
-func helperCommand(t *testing.T, s ...string) *exec.Cmd {
+func helperCommandContext(t *testing.T, ctx context.Context, s ...string) (cmd *exec.Cmd) {
 	testenv.MustHaveExec(t)
 
 	cs := []string{"-test.run=TestHelperProcess", "--"}
 	cs = append(cs, s...)
-	cmd := exec.Command(os.Args[0], cs...)
+	if ctx != nil {
+		cmd = exec.CommandContext(ctx, os.Args[0], cs...)
+	} else {
+		cmd = exec.Command(os.Args[0], cs...)
+	}
 	cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
 	path := os.Getenv("LD_LIBRARY_PATH")
 	if path != "" {
@@ -42,6 +47,10 @@ func helperCommand(t *testing.T, s ...string) *exec.Cmd {
 	return cmd
 }
 
+func helperCommand(t *testing.T, s ...string) *exec.Cmd {
+	return helperCommandContext(t, nil, s...)
+}
+
 func TestEcho(t *testing.T) {
 	bs, err := helperCommand(t, "echo", "foo bar", "baz").Output()
 	if err != nil {
@@ -345,7 +354,7 @@ func TestExtraFilesFDShuffle(t *testing.T) {
 	//
 	// We want to test that FDs in the child do not get overwritten
 	// by one another as this shuffle occurs. The original implementation
-	// was buggy in that in some data dependent cases it would ovewrite
+	// was buggy in that in some data dependent cases it would overwrite
 	// stderr in the child with one of the ExtraFile members.
 	// Testing for this case is difficult because it relies on using
 	// the same FD values as that case. In particular, an FD of 3
@@ -483,7 +492,7 @@ func TestExtraFiles(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Write: %v", err)
 	}
-	_, err = tf.Seek(0, os.SEEK_SET)
+	_, err = tf.Seek(0, io.SeekStart)
 	if err != nil {
 		t.Fatalf("Seek: %v", err)
 	}
@@ -663,10 +672,6 @@ func TestHelperProcess(*testing.T) {
 			// the cloned file descriptors that result from opening
 			// /dev/urandom.
 			// https://golang.org/issue/3955
-		case "plan9":
-			// TODO(0intro): Determine why Plan 9 is leaking
-			// file descriptors.
-			// https://golang.org/issue/7118
 		case "solaris":
 			// TODO(aram): This fails on Solaris because libc opens
 			// its own files, as it sees fit. Darwin does the same,
@@ -701,7 +706,7 @@ func TestHelperProcess(*testing.T) {
 		}
 		// Referring to fd3 here ensures that it is not
 		// garbage collected, and therefore closed, while
-		// executing the wantfd loop above.  It doesn't matter
+		// executing the wantfd loop above. It doesn't matter
 		// what we do with fd3 as long as we refer to it;
 		// closing it is the easy choice.
 		fd3.Close()
@@ -839,3 +844,111 @@ func TestOutputStderrCapture(t *testing.T) {
 		t.Errorf("ExitError.Stderr = %q; want %q", got, want)
 	}
 }
+
+func TestContext(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	c := helperCommandContext(t, ctx, "pipetest")
+	stdin, err := c.StdinPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	stdout, err := c.StdoutPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := c.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := stdin.Write([]byte("O:hi\n")); err != nil {
+		t.Fatal(err)
+	}
+	buf := make([]byte, 5)
+	n, err := io.ReadFull(stdout, buf)
+	if n != len(buf) || err != nil || string(buf) != "O:hi\n" {
+		t.Fatalf("ReadFull = %d, %v, %q", n, err, buf[:n])
+	}
+	waitErr := make(chan error, 1)
+	go func() {
+		waitErr <- c.Wait()
+	}()
+	cancel()
+	select {
+	case err := <-waitErr:
+		if err == nil {
+			t.Fatal("expected Wait failure")
+		}
+	case <-time.After(3 * time.Second):
+		t.Fatal("timeout waiting for child process death")
+	}
+}
+
+func TestContextCancel(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	c := helperCommandContext(t, ctx, "cat")
+
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.Stdin = r
+
+	stdout, err := c.StdoutPipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	readDone := make(chan struct{})
+	go func() {
+		defer close(readDone)
+		var a [1024]byte
+		for {
+			n, err := stdout.Read(a[:])
+			if err != nil {
+				if err != io.EOF {
+					t.Errorf("unexpected read error: %v", err)
+				}
+				return
+			}
+			t.Logf("%s", a[:n])
+		}
+	}()
+
+	if err := c.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := r.Close(); err != nil {
+		t.Fatal(err)
+	}
+
+	if _, err := io.WriteString(w, "echo"); err != nil {
+		t.Fatal(err)
+	}
+
+	cancel()
+
+	// Calling cancel should have killed the process, so writes
+	// should now fail.  Give the process a little while to die.
+	start := time.Now()
+	for {
+		if _, err := io.WriteString(w, "echo"); err != nil {
+			break
+		}
+		if time.Since(start) > time.Second {
+			t.Fatal("cancelling context did not stop program")
+		}
+		time.Sleep(time.Millisecond)
+	}
+
+	if err := w.Close(); err != nil {
+		t.Error("error closing write end of pipe: %v", err)
+	}
+	<-readDone
+
+	if err := c.Wait(); err == nil {
+		t.Error("program unexpectedly exited successfully")
+	} else {
+		t.Logf("exit status: %v", err)
+	}
+}
diff --git a/libgo/go/os/exec/lp_plan9.go b/libgo/go/os/exec/lp_plan9.go
index 5aa8a54ed81..142f87ed32b 100644
--- a/libgo/go/os/exec/lp_plan9.go
+++ b/libgo/go/os/exec/lp_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,6 +7,7 @@ package exec
 import (
 	"errors"
 	"os"
+	"path/filepath"
 	"strings"
 )
 
@@ -44,9 +45,10 @@ func LookPath(file string) (string, error) {
 	}
 
 	path := os.Getenv("path")
-	for _, dir := range strings.Split(path, "\000") {
-		if err := findExecutable(dir + "/" + file); err == nil {
-			return dir + "/" + file, nil
+	for _, dir := range filepath.SplitList(path) {
+		path := filepath.Join(dir, file)
+		if err := findExecutable(path); err == nil {
+			return path, nil
 		}
 	}
 	return "", &Error{file, ErrNotFound}
diff --git a/libgo/go/os/exec/lp_unix.go b/libgo/go/os/exec/lp_unix.go
index 3f895d5b3ba..7a302752a89 100644
--- a/libgo/go/os/exec/lp_unix.go
+++ b/libgo/go/os/exec/lp_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -9,6 +9,7 @@ package exec
 import (
 	"errors"
 	"os"
+	"path/filepath"
 	"strings"
 )
 
@@ -42,16 +43,13 @@ func LookPath(file string) (string, error) {
 		}
 		return "", &Error{file, err}
 	}
-	pathenv := os.Getenv("PATH")
-	if pathenv == "" {
-		return "", &Error{file, ErrNotFound}
-	}
-	for _, dir := range strings.Split(pathenv, ":") {
+	path := os.Getenv("PATH")
+	for _, dir := range filepath.SplitList(path) {
 		if dir == "" {
 			// Unix shell semantics: path element "" means "."
 			dir = "."
 		}
-		path := dir + "/" + file
+		path := filepath.Join(dir, file)
 		if err := findExecutable(path); err == nil {
 			return path, nil
 		}
diff --git a/libgo/go/os/exec/lp_unix_test.go b/libgo/go/os/exec/lp_unix_test.go
index 051db664a89..d467acf5dba 100644
--- a/libgo/go/os/exec/lp_unix_test.go
+++ b/libgo/go/os/exec/lp_unix_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/os/exec/lp_windows.go b/libgo/go/os/exec/lp_windows.go
index c3efd67e9e1..793d4d98b3a 100644
--- a/libgo/go/os/exec/lp_windows.go
+++ b/libgo/go/os/exec/lp_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -7,6 +7,7 @@ package exec
 import (
 	"errors"
 	"os"
+	"path/filepath"
 	"strings"
 )
 
@@ -46,7 +47,7 @@ func findExecutable(file string, exts []string) (string, error) {
 			return f, nil
 		}
 	}
-	return ``, os.ErrNotExist
+	return "", os.ErrNotExist
 }
 
 // LookPath searches for an executable binary named file
@@ -55,69 +56,38 @@ func findExecutable(file string, exts []string) (string, error) {
 // LookPath also uses PATHEXT environment variable to match
 // a suitable candidate.
 // The result may be an absolute path or a path relative to the current directory.
-func LookPath(file string) (f string, err error) {
+func LookPath(file string) (string, error) {
+	var exts []string
 	x := os.Getenv(`PATHEXT`)
-	if x == `` {
-		x = `.COM;.EXE;.BAT;.CMD`
-	}
-	exts := []string{}
-	for _, e := range strings.Split(strings.ToLower(x), `;`) {
-		if e == "" {
-			continue
-		}
-		if e[0] != '.' {
-			e = "." + e
-		}
-		exts = append(exts, e)
-	}
-	if strings.IndexAny(file, `:\/`) != -1 {
-		if f, err = findExecutable(file, exts); err == nil {
-			return
-		}
-		return ``, &Error{file, err}
-	}
-	if f, err = findExecutable(`.\`+file, exts); err == nil {
-		return
-	}
-	if pathenv := os.Getenv(`PATH`); pathenv != `` {
-		for _, dir := range splitList(pathenv) {
-			if f, err = findExecutable(dir+`\`+file, exts); err == nil {
-				return
+	if x != "" {
+		for _, e := range strings.Split(strings.ToLower(x), `;`) {
+			if e == "" {
+				continue
 			}
+			if e[0] != '.' {
+				e = "." + e
+			}
+			exts = append(exts, e)
 		}
+	} else {
+		exts = []string{".com", ".exe", ".bat", ".cmd"}
 	}
-	return ``, &Error{file, ErrNotFound}
-}
 
-func splitList(path string) []string {
-	// The same implementation is used in SplitList in path/filepath;
-	// consider changing path/filepath when changing this.
-
-	if path == "" {
-		return []string{}
-	}
-
-	// Split path, respecting but preserving quotes.
-	list := []string{}
-	start := 0
-	quo := false
-	for i := 0; i < len(path); i++ {
-		switch c := path[i]; {
-		case c == '"':
-			quo = !quo
-		case c == os.PathListSeparator && !quo:
-			list = append(list, path[start:i])
-			start = i + 1
+	if strings.ContainsAny(file, `:\/`) {
+		if f, err := findExecutable(file, exts); err == nil {
+			return f, nil
+		} else {
+			return "", &Error{file, err}
 		}
 	}
-	list = append(list, path[start:])
-
-	// Remove quotes.
-	for i, s := range list {
-		if strings.Contains(s, `"`) {
-			list[i] = strings.Replace(s, `"`, ``, -1)
+	if f, err := findExecutable(filepath.Join(".", file), exts); err == nil {
+		return f, nil
+	}
+	path := os.Getenv("path")
+	for _, dir := range filepath.SplitList(path) {
+		if f, err := findExecutable(filepath.Join(dir, file), exts); err == nil {
+			return f, nil
 		}
 	}
-
-	return list
+	return "", &Error{file, ErrNotFound}
 }
diff --git a/libgo/go/os/exec_posix.go b/libgo/go/os/exec_posix.go
index 94dd04beb23..3cf38b68add 100644
--- a/libgo/go/os/exec_posix.go
+++ b/libgo/go/os/exec_posix.go
@@ -21,7 +21,7 @@ var (
 func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
 	// If there is no SysProcAttr (ie. no Chroot or changed
 	// UID/GID), double-check existence of the directory we want
-	// to chdir into.  We can make the error clearer this way.
+	// to chdir into. We can make the error clearer this way.
 	if attr != nil && attr.Sys == nil && attr.Dir != "" {
 		if _, err := Stat(attr.Dir); err != nil {
 			pe := err.(*PathError)
diff --git a/libgo/go/os/exec_unix.go b/libgo/go/os/exec_unix.go
index ed97f85e22f..c4999db57f0 100644
--- a/libgo/go/os/exec_unix.go
+++ b/libgo/go/os/exec_unix.go
@@ -17,6 +17,22 @@ func (p *Process) wait() (ps *ProcessState, err error) {
 	if p.Pid == -1 {
 		return nil, syscall.EINVAL
 	}
+
+	// If we can block until Wait4 will succeed immediately, do so.
+	ready, err := p.blockUntilWaitable()
+	if err != nil {
+		return nil, err
+	}
+	if ready {
+		// Mark the process done now, before the call to Wait4,
+		// so that Process.signal will not send a signal.
+		p.setDone()
+		// Acquire a write lock on sigMu to wait for any
+		// active call to the signal method to complete.
+		p.sigMu.Lock()
+		p.sigMu.Unlock()
+	}
+
 	var status syscall.WaitStatus
 	var rusage syscall.Rusage
 	pid1, e := syscall.Wait4(p.Pid, &status, 0, &rusage)
@@ -43,6 +59,8 @@ func (p *Process) signal(sig Signal) error {
 	if p.Pid == 0 {
 		return errors.New("os: process not initialized")
 	}
+	p.sigMu.RLock()
+	defer p.sigMu.RUnlock()
 	if p.done() {
 		return errFinished
 	}
diff --git a/libgo/go/os/exec_windows.go b/libgo/go/os/exec_windows.go
index 3264271b2e9..72b5a931999 100644
--- a/libgo/go/os/exec_windows.go
+++ b/libgo/go/os/exec_windows.go
@@ -104,7 +104,7 @@ func init() {
 	defer syscall.LocalFree(syscall.Handle(uintptr(unsafe.Pointer(argv))))
 	Args = make([]string, argc)
 	for i, v := range (*argv)[:argc] {
-		Args[i] = string(syscall.UTF16ToString((*v)[:]))
+		Args[i] = syscall.UTF16ToString((*v)[:])
 	}
 }
 
diff --git a/libgo/go/os/export_test.go b/libgo/go/os/export_test.go
index 9fa7936ae63..d735aeea611 100644
--- a/libgo/go/os/export_test.go
+++ b/libgo/go/os/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/os/file.go b/libgo/go/os/file.go
index 4f8e3f3450c..e546441497b 100644
--- a/libgo/go/os/file.go
+++ b/libgo/go/os/file.go
@@ -46,6 +46,10 @@ func (f *File) Name() string { return f.name }
 
 // Stdin, Stdout, and Stderr are open Files pointing to the standard input,
 // standard output, and standard error file descriptors.
+//
+// Note that the Go runtime writes to standard error for panics and crashes;
+// closing Stderr may cause those messages to go elsewhere, perhaps
+// to a file opened later.
 var (
 	Stdin  = NewFile(uintptr(syscall.Stdin), "/dev/stdin")
 	Stdout = NewFile(uintptr(syscall.Stdout), "/dev/stdout")
@@ -66,6 +70,8 @@ const (
 )
 
 // Seek whence values.
+//
+// Deprecated: Use io.SeekStart, io.SeekCurrent, and io.SeekEnd.
 const (
 	SEEK_SET int = 0 // seek relative to the origin of the file
 	SEEK_CUR int = 1 // seek relative to the current offset
@@ -236,7 +242,7 @@ func (f *File) Chdir() error {
 	return nil
 }
 
-// Open opens the named file for reading.  If successful, methods on
+// Open opens the named file for reading. If successful, methods on
 // the returned file can be used for reading; the associated file
 // descriptor has mode O_RDONLY.
 // If there is an error, it will be of type *PathError.
diff --git a/libgo/go/os/file_plan9.go b/libgo/go/os/file_plan9.go
index c83fa028b99..9edb6bc0747 100644
--- a/libgo/go/os/file_plan9.go
+++ b/libgo/go/os/file_plan9.go
@@ -5,6 +5,7 @@
 package os
 
 import (
+	"io"
 	"runtime"
 	"syscall"
 	"time"
@@ -75,8 +76,8 @@ func syscallMode(i FileMode) (o uint32) {
 }
 
 // OpenFile is the generalized open call; most users will use Open
-// or Create instead.  It opens the named file with specified flag
-// (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
+// or Create instead. It opens the named file with specified flag
+// (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
 // methods on the returned File can be used for I/O.
 // If there is an error, it will be of type *PathError.
 func OpenFile(name string, flag int, perm FileMode) (*File, error) {
@@ -123,7 +124,7 @@ func OpenFile(name string, flag int, perm FileMode) (*File, error) {
 	}
 
 	if append {
-		if _, e = syscall.Seek(fd, 0, SEEK_END); e != nil {
+		if _, e = syscall.Seek(fd, 0, io.SeekEnd); e != nil {
 			return nil, &PathError{"seek", name, e}
 		}
 	}
@@ -145,11 +146,9 @@ func (file *file) close() error {
 		return ErrInvalid
 	}
 	var err error
-	syscall.ForkLock.RLock()
 	if e := syscall.Close(file.fd); e != nil {
 		err = &PathError{"close", file.name, e}
 	}
-	syscall.ForkLock.RUnlock()
 	file.fd = -1 // so it can't be closed again
 
 	// no need for a finalizer anymore
@@ -419,12 +418,9 @@ func Chtimes(name string, atime time.Time, mtime time.Time) error {
 func Pipe() (r *File, w *File, err error) {
 	var p [2]int
 
-	syscall.ForkLock.RLock()
 	if e := syscall.Pipe(p[0:]); e != nil {
-		syscall.ForkLock.RUnlock()
 		return nil, nil, NewSyscallError("pipe", e)
 	}
-	syscall.ForkLock.RUnlock()
 
 	return NewFile(uintptr(p[0]), "|0"), NewFile(uintptr(p[1]), "|1"), nil
 }
diff --git a/libgo/go/os/file_unix.go b/libgo/go/os/file_unix.go
index c3119cd459f..5d6c8afe112 100644
--- a/libgo/go/os/file_unix.go
+++ b/libgo/go/os/file_unix.go
@@ -78,8 +78,8 @@ func epipecheck(file *File, e error) {
 const DevNull = "/dev/null"
 
 // OpenFile is the generalized open call; most users will use Open
-// or Create instead.  It opens the named file with specified flag
-// (O_RDONLY etc.) and perm, (0666 etc.) if applicable.  If successful,
+// or Create instead. It opens the named file with specified flag
+// (O_RDONLY etc.) and perm, (0666 etc.) if applicable. If successful,
 // methods on the returned File can be used for I/O.
 // If there is an error, it will be of type *PathError.
 func OpenFile(name string, flag int, perm FileMode) (*File, error) {
@@ -114,7 +114,7 @@ func OpenFile(name string, flag int, perm FileMode) (*File, error) {
 	}
 
 	// There's a race here with fork/exec, which we are
-	// content to live with.  See ../syscall/exec_unix.go.
+	// content to live with. See ../syscall/exec_unix.go.
 	if !supportsCloseOnExec {
 		syscall.CloseOnExec(r)
 	}
@@ -187,7 +187,7 @@ func Stat(name string) (FileInfo, error) {
 
 // Lstat returns a FileInfo describing the named file.
 // If the file is a symbolic link, the returned FileInfo
-// describes the symbolic link.  Lstat makes no attempt to follow the link.
+// describes the symbolic link. Lstat makes no attempt to follow the link.
 // If there is an error, it will be of type *PathError.
 func Lstat(name string) (FileInfo, error) {
 	var fs fileStat
@@ -322,7 +322,7 @@ func Remove(name string) error {
 
 	// Both failed: figure out which error to return.
 	// OS X and Linux differ on whether unlink(dir)
-	// returns EISDIR, so can't use that.  However,
+	// returns EISDIR, so can't use that. However,
 	// both agree that rmdir(file) returns ENOTDIR,
 	// so we can use that to decide which error is real.
 	// Rmdir might also return ENOTDIR if given a bad
diff --git a/libgo/go/os/getwd.go b/libgo/go/os/getwd.go
index d5da53b34bf..4c3c0d94cb0 100644
--- a/libgo/go/os/getwd.go
+++ b/libgo/go/os/getwd.go
@@ -20,7 +20,7 @@ var getwdCache struct {
 var useSyscallwd = func(error) bool { return true }
 
 // Getwd returns a rooted path name corresponding to the
-// current directory.  If the current directory can be
+// current directory. If the current directory can be
 // reached via multiple paths (due to symbolic links),
 // Getwd may return any one of them.
 func Getwd() (dir string, err error) {
@@ -74,7 +74,7 @@ func Getwd() (dir string, err error) {
 	}
 
 	// General algorithm: find name in parent
-	// and then find name of parent.  Each iteration
+	// and then find name of parent. Each iteration
 	// adds /name to the beginning of dir.
 	dir = ""
 	for parent := ".."; ; parent = "../" + parent {
diff --git a/libgo/go/os/os_test.go b/libgo/go/os/os_test.go
index 5497704e167..abc638e2fab 100644
--- a/libgo/go/os/os_test.go
+++ b/libgo/go/os/os_test.go
@@ -45,10 +45,10 @@ var sysdir = func() *sysDir {
 	switch runtime.GOOS {
 	case "android":
 		return &sysDir{
-			"/system/framework",
+			"/system/lib",
 			[]string{
-				"ext.jar",
-				"framework.jar",
+				"libmedia.so",
+				"libpowermanager.so",
 			},
 		}
 	case "darwin":
@@ -536,7 +536,7 @@ func TestReaddirStatFailures(t *testing.T) {
 		return s
 	}
 
-	if got, want := names(mustReadDir("inital readdir")),
+	if got, want := names(mustReadDir("initial readdir")),
 		[]string{"good1", "good2", "x"}; !reflect.DeepEqual(got, want) {
 		t.Errorf("initial readdir got %q; want %q", got, want)
 	}
@@ -1180,14 +1180,14 @@ func TestSeek(t *testing.T) {
 		out    int64
 	}
 	var tests = []test{
-		{0, 1, int64(len(data))},
-		{0, 0, 0},
-		{5, 0, 5},
-		{0, 2, int64(len(data))},
-		{0, 0, 0},
-		{-1, 2, int64(len(data)) - 1},
-		{1 << 33, 0, 1 << 33},
-		{1 << 33, 2, 1<<33 + int64(len(data))},
+		{0, io.SeekCurrent, int64(len(data))},
+		{0, io.SeekStart, 0},
+		{5, io.SeekStart, 5},
+		{0, io.SeekEnd, int64(len(data))},
+		{0, io.SeekStart, 0},
+		{-1, io.SeekEnd, int64(len(data)) - 1},
+		{1 << 33, io.SeekStart, 1 << 33},
+		{1 << 33, io.SeekEnd, 1<<33 + int64(len(data))},
 	}
 	for i, tt := range tests {
 		off, err := f.Seek(tt.in, tt.whence)
@@ -1273,15 +1273,19 @@ func TestOpenNoName(t *testing.T) {
 	}
 }
 
-func run(t *testing.T, cmd []string) string {
+func runBinHostname(t *testing.T) string {
 	// Run /bin/hostname and collect output.
 	r, w, err := Pipe()
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer r.Close()
-	p, err := StartProcess("/bin/hostname", []string{"hostname"}, &ProcAttr{Files: []*File{nil, w, Stderr}})
+	const path = "/bin/hostname"
+	p, err := StartProcess(path, []string{"hostname"}, &ProcAttr{Files: []*File{nil, w, Stderr}})
 	if err != nil {
+		if _, err := Stat(path); IsNotExist(err) {
+			t.Skipf("skipping test; test requires %s but it does not exist", path)
+		}
 		t.Fatal(err)
 	}
 	w.Close()
@@ -1301,7 +1305,7 @@ func run(t *testing.T, cmd []string) string {
 		output = output[0 : n-1]
 	}
 	if output == "" {
-		t.Fatalf("%v produced no output", cmd)
+		t.Fatalf("/bin/hostname produced no output")
 	}
 
 	return output
@@ -1343,7 +1347,7 @@ func TestHostname(t *testing.T) {
 	if err != nil {
 		t.Fatalf("%v", err)
 	}
-	want := run(t, []string{"/bin/hostname"})
+	want := runBinHostname(t)
 	if hostname != want {
 		i := strings.Index(hostname, ".")
 		if i < 0 || hostname[0:i] != want {
@@ -1370,6 +1374,38 @@ func TestReadAt(t *testing.T) {
 	}
 }
 
+// Verify that ReadAt doesn't affect seek offset.
+// In the Plan 9 kernel, there used to be a bug in the implementation of
+// the pread syscall, where the channel offset was erroneously updated after
+// calling pread on a file.
+func TestReadAtOffset(t *testing.T) {
+	f := newFile("TestReadAtOffset", t)
+	defer Remove(f.Name())
+	defer f.Close()
+
+	const data = "hello, world\n"
+	io.WriteString(f, data)
+
+	f.Seek(0, 0)
+	b := make([]byte, 5)
+
+	n, err := f.ReadAt(b, 7)
+	if err != nil || n != len(b) {
+		t.Fatalf("ReadAt 7: %d, %v", n, err)
+	}
+	if string(b) != "world" {
+		t.Fatalf("ReadAt 7: have %q want %q", string(b), "world")
+	}
+
+	n, err = f.Read(b)
+	if err != nil || n != len(b) {
+		t.Fatalf("Read: %d, %v", n, err)
+	}
+	if string(b) != "hello" {
+		t.Fatalf("Read: have %q want %q", string(b), "hello")
+	}
+}
+
 func TestWriteAt(t *testing.T) {
 	f := newFile("TestWriteAt", t)
 	defer Remove(f.Name())
@@ -1577,6 +1613,42 @@ func TestStatDirModeExec(t *testing.T) {
 	}
 }
 
+func TestStatStdin(t *testing.T) {
+	switch runtime.GOOS {
+	case "android", "plan9":
+		t.Skipf("%s doesn't have /bin/sh", runtime.GOOS)
+	}
+
+	testenv.MustHaveExec(t)
+
+	if Getenv("GO_WANT_HELPER_PROCESS") == "1" {
+		st, err := Stdin.Stat()
+		if err != nil {
+			t.Fatalf("Stat failed: %v", err)
+		}
+		fmt.Println(st.Mode() & ModeNamedPipe)
+		Exit(0)
+	}
+
+	var cmd *osexec.Cmd
+	if runtime.GOOS == "windows" {
+		cmd = osexec.Command("cmd", "/c", "echo output | "+Args[0]+" -test.run=TestStatStdin")
+	} else {
+		cmd = osexec.Command("/bin/sh", "-c", "echo output | "+Args[0]+" -test.run=TestStatStdin")
+	}
+	cmd.Env = append(Environ(), "GO_WANT_HELPER_PROCESS=1")
+
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("Failed to spawn child process: %v %q", err, string(output))
+	}
+
+	// result will be like "prw-rw-rw"
+	if len(output) < 1 || output[0] != 'p' {
+		t.Fatalf("Child process reports stdin is not pipe '%v'", string(output))
+	}
+}
+
 func TestReadAtEOF(t *testing.T) {
 	f := newFile("TestReadAtEOF", t)
 	defer Remove(f.Name())
@@ -1684,7 +1756,7 @@ var nilFileMethodTests = []struct {
 	{"ReadAt", func(f *File) error { _, err := f.ReadAt(make([]byte, 0), 0); return err }},
 	{"Readdir", func(f *File) error { _, err := f.Readdir(1); return err }},
 	{"Readdirnames", func(f *File) error { _, err := f.Readdirnames(1); return err }},
-	{"Seek", func(f *File) error { _, err := f.Seek(0, 0); return err }},
+	{"Seek", func(f *File) error { _, err := f.Seek(0, io.SeekStart); return err }},
 	{"Stat", func(f *File) error { _, err := f.Stat(); return err }},
 	{"Sync", func(f *File) error { return f.Sync() }},
 	{"Truncate", func(f *File) error { return f.Truncate(0) }},
diff --git a/libgo/go/os/os_unix_test.go b/libgo/go/os/os_unix_test.go
index d02e07b478a..5c10154760c 100644
--- a/libgo/go/os/os_unix_test.go
+++ b/libgo/go/os/os_unix_test.go
@@ -39,7 +39,7 @@ func TestChown(t *testing.T) {
 	}
 	// Use TempDir() to make sure we're on a local file system,
 	// so that the group ids returned by Getgroups will be allowed
-	// on the file.  On NFS, the Getgroups groups are
+	// on the file. On NFS, the Getgroups groups are
 	// basically useless.
 	f := newFile("TestChown", t)
 	defer Remove(f.Name())
@@ -50,7 +50,7 @@ func TestChown(t *testing.T) {
 	}
 
 	// Can't change uid unless root, but can try
-	// changing the group id.  First try our current group.
+	// changing the group id. First try our current group.
 	gid := Getgid()
 	t.Log("gid:", gid)
 	if err = Chown(f.Name(), -1, gid); err != nil {
@@ -86,7 +86,7 @@ func TestFileChown(t *testing.T) {
 	}
 	// Use TempDir() to make sure we're on a local file system,
 	// so that the group ids returned by Getgroups will be allowed
-	// on the file.  On NFS, the Getgroups groups are
+	// on the file. On NFS, the Getgroups groups are
 	// basically useless.
 	f := newFile("TestFileChown", t)
 	defer Remove(f.Name())
@@ -97,7 +97,7 @@ func TestFileChown(t *testing.T) {
 	}
 
 	// Can't change uid unless root, but can try
-	// changing the group id.  First try our current group.
+	// changing the group id. First try our current group.
 	gid := Getgid()
 	t.Log("gid:", gid)
 	if err = f.Chown(-1, gid); err != nil {
@@ -133,7 +133,7 @@ func TestLchown(t *testing.T) {
 	}
 	// Use TempDir() to make sure we're on a local file system,
 	// so that the group ids returned by Getgroups will be allowed
-	// on the file.  On NFS, the Getgroups groups are
+	// on the file. On NFS, the Getgroups groups are
 	// basically useless.
 	f := newFile("TestLchown", t)
 	defer Remove(f.Name())
@@ -145,12 +145,15 @@ func TestLchown(t *testing.T) {
 
 	linkname := f.Name() + "2"
 	if err := Symlink(f.Name(), linkname); err != nil {
+		if runtime.GOOS == "android" && IsPermission(err) {
+			t.Skip("skipping test on Android; permission error creating symlink")
+		}
 		t.Fatalf("link %s -> %s: %v", f.Name(), linkname, err)
 	}
 	defer Remove(linkname)
 
 	// Can't change uid unless root, but can try
-	// changing the group id.  First try our current group.
+	// changing the group id. First try our current group.
 	gid := Getgid()
 	t.Log("gid:", gid)
 	if err = Lchown(linkname, -1, gid); err != nil {
diff --git a/libgo/go/os/path.go b/libgo/go/os/path.go
index 84a3be3348f..146d7b69548 100644
--- a/libgo/go/os/path.go
+++ b/libgo/go/os/path.go
@@ -61,7 +61,7 @@ func MkdirAll(path string, perm FileMode) error {
 
 // RemoveAll removes path and any children it contains.
 // It removes everything it can but returns the first error
-// it encounters.  If the path does not exist, RemoveAll
+// it encounters. If the path does not exist, RemoveAll
 // returns nil (no error).
 func RemoveAll(path string) error {
 	// Simple case: if Remove works, we're done.
diff --git a/libgo/go/os/path_test.go b/libgo/go/os/path_test.go
index b4531314d04..51dc25bb230 100644
--- a/libgo/go/os/path_test.go
+++ b/libgo/go/os/path_test.go
@@ -147,7 +147,7 @@ func TestRemoveAll(t *testing.T) {
 		// No error checking here: either RemoveAll
 		// will or won't be able to remove dpath;
 		// either way we want to see if it removes fpath
-		// and path/zzz.  Reasons why RemoveAll might
+		// and path/zzz. Reasons why RemoveAll might
 		// succeed in removing dpath as well include:
 		//	* running as root
 		//	* running on a file system without permissions (FAT)
diff --git a/libgo/go/os/pipe_test.go b/libgo/go/os/pipe_test.go
index 82b792eac49..74cce80ee4b 100644
--- a/libgo/go/os/pipe_test.go
+++ b/libgo/go/os/pipe_test.go
@@ -88,7 +88,7 @@ func TestStdPipe(t *testing.T) {
 	}
 }
 
-// This is a helper for TestStdPipe.  It's not a test in itself.
+// This is a helper for TestStdPipe. It's not a test in itself.
 func TestStdPipeHelper(t *testing.T) {
 	if os.Getenv("GO_TEST_STD_PIPE_HELPER_SIGNAL") != "" {
 		signal.Notify(make(chan os.Signal, 1), syscall.SIGPIPE)
diff --git a/libgo/go/os/signal/doc.go b/libgo/go/os/signal/doc.go
index 80e66cffe53..73b01a2764d 100644
--- a/libgo/go/os/signal/doc.go
+++ b/libgo/go/os/signal/doc.go
@@ -11,7 +11,7 @@ package on Windows and Plan 9, see below.
 Types of signals
 
 The signals SIGKILL and SIGSTOP may not be caught by a program, and
-therefore can not be affected by this package.
+therefore cannot be affected by this package.
 
 Synchronous signals are signals triggered by errors in program
 execution: SIGBUS, SIGFPE, and SIGSEGV. These are only considered
@@ -205,8 +205,8 @@ before raising the signal.
 Windows
 
 On Windows a ^C (Control-C) or ^BREAK (Control-Break) normally cause
-the program to exit. If Notify is called for os.SIGINT, ^C or ^BREAK
-will cause os.SIGINT to be sent on the channel, and the program will
+the program to exit. If Notify is called for os.Interrupt, ^C or ^BREAK
+will cause os.Interrupt to be sent on the channel, and the program will
 not exit. If Reset is called, or Stop is called on all channels passed
 to Notify, then the default behavior will be restored.
 
diff --git a/libgo/go/os/signal/signal.go b/libgo/go/os/signal/signal.go
index 2e6f1866583..c1376daaea6 100644
--- a/libgo/go/os/signal/signal.go
+++ b/libgo/go/os/signal/signal.go
@@ -79,7 +79,7 @@ func Ignore(sig ...os.Signal) {
 //
 // Package signal will not block sending to c: the caller must ensure
 // that c has sufficient buffer space to keep up with the expected
-// signal rate.  For a channel used for notification of just one signal value,
+// signal rate. For a channel used for notification of just one signal value,
 // a buffer of size 1 is sufficient.
 //
 // It is allowed to call Notify multiple times with the same channel:
diff --git a/libgo/go/os/signal/signal_test.go b/libgo/go/os/signal/signal_test.go
index 56d786e5015..406102c663b 100644
--- a/libgo/go/os/signal/signal_test.go
+++ b/libgo/go/os/signal/signal_test.go
@@ -139,6 +139,19 @@ func testCancel(t *testing.T, ignore bool) {
 		Reset(syscall.SIGWINCH, syscall.SIGHUP)
 	}
 
+	// At this point we do not expect any further signals on c1.
+	// However, it is just barely possible that the initial SIGWINCH
+	// at the start of this function was delivered after we called
+	// Notify on c1. In that case the waitSig for SIGWINCH may have
+	// picked up that initial SIGWINCH, and the second SIGWINCH may
+	// then have been delivered on the channel. This sequence of events
+	// may have caused issue 15661.
+	// So, read any possible signal from the channel now.
+	select {
+	case <-c1:
+	default:
+	}
+
 	// Send this process a SIGWINCH. It should be ignored.
 	syscall.Kill(syscall.Getpid(), syscall.SIGWINCH)
 
diff --git a/libgo/go/os/stat_dragonfly.go b/libgo/go/os/stat_dragonfly.go
index 69e63230eb3..217bc6726d2 100644
--- a/libgo/go/os/stat_dragonfly.go
+++ b/libgo/go/os/stat_dragonfly.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtim)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
@@ -42,7 +42,7 @@ func fillFileStatFromSys(fs *fileStat, name string) {
 }
 
 func timespecToTime(ts syscall.Timespec) time.Time {
-	return time.Unix(int64(ts.Sec), int64(ts.Nsec))
+	return time.Unix(ts.Sec, ts.Nsec)
 }
 
 // For testing.
diff --git a/libgo/go/os/stat_nacl.go b/libgo/go/os/stat_nacl.go
index d3bed14e430..0c53f2faa43 100644
--- a/libgo/go/os/stat_nacl.go
+++ b/libgo/go/os/stat_nacl.go
@@ -11,7 +11,7 @@ import (
 
 func fillFileStatFromSys(fs *fileStat, name string) {
 	fs.name = basename(name)
-	fs.size = int64(fs.sys.Size)
+	fs.size = fs.sys.Size
 	fs.modTime = timespecToTime(fs.sys.Mtime, fs.sys.MtimeNsec)
 	fs.mode = FileMode(fs.sys.Mode & 0777)
 	switch fs.sys.Mode & syscall.S_IFMT {
diff --git a/libgo/go/os/stat_plan9.go b/libgo/go/os/stat_plan9.go
index fa4bd83aefb..96f056c1117 100644
--- a/libgo/go/os/stat_plan9.go
+++ b/libgo/go/os/stat_plan9.go
@@ -20,7 +20,7 @@ func sameFile(fs1, fs2 *fileStat) bool {
 func fileInfoFromStat(d *syscall.Dir) FileInfo {
 	fs := &fileStat{
 		name:    d.Name,
-		size:    int64(d.Length),
+		size:    d.Length,
 		modTime: time.Unix(int64(d.Mtime), 0),
 		sys:     d,
 	}
@@ -100,7 +100,7 @@ func Stat(name string) (FileInfo, error) {
 
 // Lstat returns a FileInfo describing the named file.
 // If the file is a symbolic link, the returned FileInfo
-// describes the symbolic link.  Lstat makes no attempt to follow the link.
+// describes the symbolic link. Lstat makes no attempt to follow the link.
 // If there is an error, it will be of type *PathError.
 func Lstat(name string) (FileInfo, error) {
 	return Stat(name)
diff --git a/libgo/go/os/str.go b/libgo/go/os/str.go
index d3e03e98495..cba9fa3e8d4 100644
--- a/libgo/go/os/str.go
+++ b/libgo/go/os/str.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Simple converions to avoid depending on strconv.
+// Simple conversions to avoid depending on strconv.
 
 package os
 
diff --git a/libgo/go/os/types.go b/libgo/go/os/types.go
index 9d6f8e13d6f..12b593fa1eb 100644
--- a/libgo/go/os/types.go
+++ b/libgo/go/os/types.go
@@ -25,7 +25,7 @@ type FileInfo interface {
 // A FileMode represents a file's mode and permission bits.
 // The bits have the same definition on all systems, so that
 // information about files can be moved from one system
-// to another portably.  Not all bits apply to all systems.
+// to another portably. Not all bits apply to all systems.
 // The only required bit is ModeDir for directories.
 type FileMode uint32
 
diff --git a/libgo/go/os/types_windows.go b/libgo/go/os/types_windows.go
index 7b2e54698c3..ad4e863fcbb 100644
--- a/libgo/go/os/types_windows.go
+++ b/libgo/go/os/types_windows.go
@@ -14,6 +14,7 @@ import (
 type fileStat struct {
 	name string
 	sys  syscall.Win32FileAttributeData
+	pipe bool
 
 	// used to implement SameFile
 	sync.Mutex
@@ -42,6 +43,9 @@ func (fs *fileStat) Mode() (m FileMode) {
 	if fs.sys.FileAttributes&syscall.FILE_ATTRIBUTE_REPARSE_POINT != 0 {
 		m |= ModeSymlink
 	}
+	if fs.pipe {
+		m |= ModeNamedPipe
+	}
 	return m
 }
 
@@ -69,7 +73,7 @@ func (fs *fileStat) loadFileId() error {
 	}
 	defer syscall.CloseHandle(h)
 	var i syscall.ByHandleFileInformation
-	err = syscall.GetFileInformationByHandle(syscall.Handle(h), &i)
+	err = syscall.GetFileInformationByHandle(h, &i)
 	if err != nil {
 		return err
 	}
diff --git a/libgo/go/os/user/decls_solaris.go b/libgo/go/os/user/decls_solaris.go
index 788a00f0661..969b48c9e80 100644
--- a/libgo/go/os/user/decls_solaris.go
+++ b/libgo/go/os/user/decls_solaris.go
@@ -16,3 +16,9 @@ func libc_getpwnam_r(name *byte, pwd *syscall.Passwd, buf *byte, buflen syscall.
 
 //extern __posix_getpwuid_r
 func libc_getpwuid_r(uid syscall.Uid_t, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int
+
+//extern __posix_getgrnam_r
+func libc_getgrnam_r(name *byte, grp *syscall.Group, buf *byte, buflen syscall.Size_t, result **syscall.Group) int
+
+//extern __posix_getgrgid_r
+func libc_getgrgid_r(gid syscall.Gid_t, grp *syscall.group, buf *byte, buflen syscall.Size_t, result **syscall.group) int
diff --git a/libgo/go/os/user/decls_unix.go b/libgo/go/os/user/decls_unix.go
index f76e4c9bdfc..c2eb51e5bb4 100644
--- a/libgo/go/os/user/decls_unix.go
+++ b/libgo/go/os/user/decls_unix.go
@@ -16,3 +16,12 @@ func libc_getpwnam_r(name *byte, pwd *syscall.Passwd, buf *byte, buflen syscall.
 
 //extern getpwuid_r
 func libc_getpwuid_r(uid syscall.Uid_t, pwd *syscall.Passwd, buf *byte, buflen syscall.Size_t, result **syscall.Passwd) int
+
+//extern getgrnam_r
+func libc_getgrnam_r(name *byte, grp *syscall.Group, buf *byte, buflen syscall.Size_t, result **syscall.Group) int
+
+//extern getgrgid_r
+func libc_getgrgid_r(gid syscall.Gid_t, grp *syscall.Group, buf *byte, buflen syscall.Size_t, result **syscall.Group) int
+
+//extern getgrouplist
+func libc_getgrouplist(user *byte, group syscall.Gid_t, groups *syscall.Gid_t, ngroups *int32) int
diff --git a/libgo/go/os/user/listgroups_solaris.go b/libgo/go/os/user/listgroups_solaris.go
new file mode 100644
index 00000000000..28a8a78dbbc
--- /dev/null
+++ b/libgo/go/os/user/listgroups_solaris.go
@@ -0,0 +1,17 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build cgo
+
+// Even though this file requires no C, it is used to provide a
+// listGroup stub because all the other Solaris calls work.  Otherwise,
+// this stub will conflict with the lookup_stubs.go fallback.
+
+package user
+
+import "fmt"
+
+func listGroups(u *User) ([]string, error) {
+	return nil, fmt.Errorf("user: list groups for %s: not supported on Solaris", u.Username)
+}
diff --git a/libgo/go/os/user/listgroups_unix.go b/libgo/go/os/user/listgroups_unix.go
new file mode 100644
index 00000000000..8b2b13d563f
--- /dev/null
+++ b/libgo/go/os/user/listgroups_unix.go
@@ -0,0 +1,57 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build dragonfly darwin freebsd !android,linux netbsd openbsd
+
+package user
+
+import (
+	"fmt"
+	"strconv"
+	"syscall"
+)
+
+/*
+#include <unistd.h>
+#include <sys/types.h>
+#include <stdlib.h>
+*/
+
+func listGroups(u *User) ([]string, error) {
+	ug, err := strconv.Atoi(u.Gid)
+	if err != nil {
+		return nil, fmt.Errorf("user: list groups for %s: invalid gid %q", u.Username, u.Gid)
+	}
+	userGID := syscall.Gid_t(ug)
+	nameC, err := syscall.BytePtrFromString(u.Username)
+	if err != nil {
+		return nil, fmt.Errorf("user: invalid user name %q: %v", strconv.Quote(u.Username), err)
+	}
+
+	n := int32(256)
+	gidsC := make([]syscall.Gid_t, n)
+	syscall.Entersyscall()
+	rv := libc_getgrouplist(nameC, userGID, &gidsC[0], &n)
+	syscall.Exitsyscall()
+	if rv == -1 {
+		// More than initial buffer, but now n contains the correct size.
+		const maxGroups = 2048
+		if n > maxGroups {
+			return nil, fmt.Errorf("user: list groups for %s: member of more than %d groups", u.Username, maxGroups)
+		}
+		gidsC = make([]syscall.Gid_t, n)
+		syscall.Entersyscall()
+		rv := libc_getgrouplist(nameC, userGID, &gidsC[0], &n)
+		syscall.Exitsyscall()
+		if rv == -1 {
+			return nil, fmt.Errorf("user: list groups for %s failed (changed groups?)", u.Username)
+		}
+	}
+	gidsC = gidsC[:n]
+	gids := make([]string, 0, n)
+	for _, g := range gidsC[:n] {
+		gids = append(gids, strconv.Itoa(int(g)))
+	}
+	return gids, nil
+}
diff --git a/libgo/go/os/user/lookup.go b/libgo/go/os/user/lookup.go
index 09f00c7bdb4..3b4421badd5 100644
--- a/libgo/go/os/user/lookup.go
+++ b/libgo/go/os/user/lookup.go
@@ -12,11 +12,28 @@ func Current() (*User, error) {
 // Lookup looks up a user by username. If the user cannot be found, the
 // returned error is of type UnknownUserError.
 func Lookup(username string) (*User, error) {
-	return lookup(username)
+	return lookupUser(username)
 }
 
 // LookupId looks up a user by userid. If the user cannot be found, the
 // returned error is of type UnknownUserIdError.
 func LookupId(uid string) (*User, error) {
-	return lookupId(uid)
+	return lookupUserId(uid)
+}
+
+// LookupGroup looks up a group by name. If the group cannot be found, the
+// returned error is of type UnknownGroupError.
+func LookupGroup(name string) (*Group, error) {
+	return lookupGroup(name)
+}
+
+// LookupGroupId looks up a group by groupid. If the group cannot be found, the
+// returned error is of type UnknownGroupIdError.
+func LookupGroupId(gid string) (*Group, error) {
+	return lookupGroupId(gid)
+}
+
+// GroupIds returns the list of group IDs that the user is a member of.
+func (u *User) GroupIds() ([]string, error) {
+	return listGroups(u)
 }
diff --git a/libgo/go/os/user/lookup_android.go b/libgo/go/os/user/lookup_android.go
new file mode 100644
index 00000000000..b1be3dc1931
--- /dev/null
+++ b/libgo/go/os/user/lookup_android.go
@@ -0,0 +1,38 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build android
+
+package user
+
+import "errors"
+
+func init() {
+	userImplemented = false
+	groupImplemented = false
+}
+
+func current() (*User, error) {
+	return nil, errors.New("user: Current not implemented on android")
+}
+
+func lookupUser(string) (*User, error) {
+	return nil, errors.New("user: Lookup not implemented on android")
+}
+
+func lookupUserId(string) (*User, error) {
+	return nil, errors.New("user: LookupId not implemented on android")
+}
+
+func lookupGroup(string) (*Group, error) {
+	return nil, errors.New("user: LookupGroup not implemented on android")
+}
+
+func lookupGroupId(string) (*Group, error) {
+	return nil, errors.New("user: LookupGroupId not implemented on android")
+}
+
+func listGroups(*User) ([]string, error) {
+	return nil, errors.New("user: GroupIds not implemented on android")
+}
diff --git a/libgo/go/os/user/lookup_plan9.go b/libgo/go/os/user/lookup_plan9.go
index f7ef3482b7e..ea3ce0bc7cf 100644
--- a/libgo/go/os/user/lookup_plan9.go
+++ b/libgo/go/os/user/lookup_plan9.go
@@ -18,6 +18,10 @@ const (
 	userFile = "/dev/user"
 )
 
+func init() {
+	groupImplemented = false
+}
+
 func current() (*User, error) {
 	ubytes, err := ioutil.ReadFile(userFile)
 	if err != nil {
@@ -37,10 +41,22 @@ func current() (*User, error) {
 	return u, nil
 }
 
-func lookup(username string) (*User, error) {
+func lookupUser(username string) (*User, error) {
+	return nil, syscall.EPLAN9
+}
+
+func lookupUserId(uid string) (*User, error) {
+	return nil, syscall.EPLAN9
+}
+
+func lookupGroup(groupname string) (*Group, error) {
+	return nil, syscall.EPLAN9
+}
+
+func lookupGroupId(string) (*Group, error) {
 	return nil, syscall.EPLAN9
 }
 
-func lookupId(uid string) (*User, error) {
+func listGroups(*User) ([]string, error) {
 	return nil, syscall.EPLAN9
 }
diff --git a/libgo/go/os/user/lookup_stubs.go b/libgo/go/os/user/lookup_stubs.go
index 4fb0e3c6edd..ebf24f79dee 100644
--- a/libgo/go/os/user/lookup_stubs.go
+++ b/libgo/go/os/user/lookup_stubs.go
@@ -2,27 +2,83 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !cgo,!windows,!plan9 android
+// +build !cgo,!windows,!plan9,!android
 
 package user
 
 import (
+	"errors"
 	"fmt"
+	"os"
 	"runtime"
+	"strconv"
 )
 
 func init() {
-	implemented = false
+	userImplemented = false
+	groupImplemented = false
 }
 
 func current() (*User, error) {
-	return nil, fmt.Errorf("user: Current not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+	u := &User{
+		Uid:      currentUID(),
+		Gid:      currentGID(),
+		Username: os.Getenv("USER"),
+		Name:     "", // ignored
+		HomeDir:  os.Getenv("HOME"),
+	}
+	if runtime.GOOS == "nacl" {
+		if u.Uid == "" {
+			u.Uid = "1"
+		}
+		if u.Username == "" {
+			u.Username = "nacl"
+		}
+		if u.HomeDir == "" {
+			u.HomeDir = "/home/nacl"
+		}
+	}
+	// cgo isn't available, but if we found the minimum information
+	// without it, use it:
+	if u.Uid != "" && u.Username != "" && u.HomeDir != "" {
+		return u, nil
+	}
+	return u, fmt.Errorf("user: Current not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
 }
 
-func lookup(username string) (*User, error) {
-	return nil, fmt.Errorf("user: Lookup not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+func lookupUser(username string) (*User, error) {
+	return nil, errors.New("user: Lookup requires cgo")
 }
 
-func lookupId(uid string) (*User, error) {
-	return nil, fmt.Errorf("user: LookupId not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+func lookupUserId(uid string) (*User, error) {
+	return nil, errors.New("user: LookupId requires cgo")
+}
+
+func lookupGroup(groupname string) (*Group, error) {
+	return nil, errors.New("user: LookupGroup requires cgo")
+}
+
+func lookupGroupId(string) (*Group, error) {
+	return nil, errors.New("user: LookupGroupId requires cgo")
+}
+
+func listGroups(*User) ([]string, error) {
+	return nil, errors.New("user: GroupIds requires cgo")
+}
+
+func currentUID() string {
+	if id := os.Getuid(); id >= 0 {
+		return strconv.Itoa(id)
+	}
+	// Note: Windows returns -1, but this file isn't used on
+	// Windows anyway, so this empty return path shouldn't be
+	// used.
+	return ""
+}
+
+func currentGID() string {
+	if id := os.Getgid(); id >= 0 {
+		return strconv.Itoa(id)
+	}
+	return ""
 }
diff --git a/libgo/go/os/user/lookup_unix.go b/libgo/go/os/user/lookup_unix.go
index bebb9e8f2b0..8881366cf9f 100644
--- a/libgo/go/os/user/lookup_unix.go
+++ b/libgo/go/os/user/lookup_unix.go
@@ -15,24 +15,6 @@ import (
 	"unsafe"
 )
 
-/*
-#cgo solaris CFLAGS: -D_POSIX_PTHREAD_SEMANTICS
-#include <unistd.h>
-#include <sys/types.h>
-#include <pwd.h>
-#include <stdlib.h>
-
-static int mygetpwuid_r(int uid, struct passwd *pwd,
-	char *buf, size_t buflen, struct passwd **result) {
-	return getpwuid_r(uid, pwd, buf, buflen, result);
-}
-
-static int mygetpwnam_r(const char *name, struct passwd *pwd,
-	char *buf, size_t buflen, struct passwd **result) {
-	return getpwnam_r(name, pwd, buf, buflen, result);
-}
-*/
-
 // bytePtrToString takes a NUL-terminated array of bytes and convert
 // it to a Go string.
 func bytePtrToString(p *byte) string {
@@ -45,58 +27,77 @@ func bytePtrToString(p *byte) string {
 }
 
 func current() (*User, error) {
-	return lookupUnix(syscall.Getuid(), "", false)
+	return lookupUnixUid(syscall.Getuid())
 }
 
-func lookup(username string) (*User, error) {
-	return lookupUnix(-1, username, true)
+func lookupUser(username string) (*User, error) {
+	var pwd syscall.Passwd
+	var result *syscall.Passwd
+	p := syscall.StringBytePtr(username)
+
+	buf := alloc(userBuffer)
+	defer buf.free()
+
+	err := retryWithBuffer(buf, func() syscall.Errno {
+		syscall.Entersyscall()
+		rv := libc_getpwnam_r(p,
+			&pwd,
+			buf.ptr,
+			buf.size,
+			&result)
+		syscall.Exitsyscall()
+		if rv != 0 {
+			return syscall.GetErrno()
+		}
+		return 0
+	})
+	if err != nil {
+		return nil, fmt.Errorf("user: lookup username %s: %v", username, err)
+	}
+	if result == nil {
+		return nil, UnknownUserError(username)
+	}
+	return buildUser(&pwd), err
 }
 
-func lookupId(uid string) (*User, error) {
+func lookupUserId(uid string) (*User, error) {
 	i, e := strconv.Atoi(uid)
 	if e != nil {
 		return nil, e
 	}
-	return lookupUnix(i, "", false)
+	return lookupUnixUid(i)
 }
 
-func lookupUnix(uid int, username string, lookupByName bool) (*User, error) {
+func lookupUnixUid(uid int) (*User, error) {
 	var pwd syscall.Passwd
 	var result *syscall.Passwd
 
-	// FIXME: Should let buf grow if necessary.
-	const bufSize = 1024
-	buf := make([]byte, bufSize)
-	if lookupByName {
-		nameC := syscall.StringBytePtr(username)
-		syscall.Entersyscall()
-		rv := libc_getpwnam_r(nameC,
-			&pwd,
-			&buf[0],
-			bufSize,
-			&result)
-		syscall.Exitsyscall()
-		if rv != 0 {
-			return nil, fmt.Errorf("user: lookup username %s: %s", username, syscall.GetErrno())
-		}
-		if result == nil {
-			return nil, UnknownUserError(username)
-		}
-	} else {
+	buf := alloc(userBuffer)
+	defer buf.free()
+
+	err := retryWithBuffer(buf, func() syscall.Errno {
 		syscall.Entersyscall()
 		rv := libc_getpwuid_r(syscall.Uid_t(uid),
 			&pwd,
-			&buf[0],
-			bufSize,
+			buf.ptr,
+			buf.size,
 			&result)
 		syscall.Exitsyscall()
 		if rv != 0 {
-			return nil, fmt.Errorf("user: lookup userid %d: %s", uid, syscall.GetErrno())
-		}
-		if result == nil {
-			return nil, UnknownUserIdError(uid)
+			return syscall.GetErrno()
 		}
+		return 0
+	})
+	if err != nil {
+		return nil, fmt.Errorf("user: lookup userid %d: %v", uid, err)
+	}
+	if result == nil {
+		return nil, UnknownUserIdError(uid)
 	}
+	return buildUser(&pwd), nil
+}
+
+func buildUser(pwd *syscall.Passwd) *User {
 	u := &User{
 		Uid:      strconv.Itoa(int(pwd.Pw_uid)),
 		Gid:      strconv.Itoa(int(pwd.Pw_gid)),
@@ -104,12 +105,162 @@ func lookupUnix(uid int, username string, lookupByName bool) (*User, error) {
 		Name:     bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_gecos))),
 		HomeDir:  bytePtrToString((*byte)(unsafe.Pointer(pwd.Pw_dir))),
 	}
-	// The pw_gecos field isn't quite standardized.  Some docs
+	// The pw_gecos field isn't quite standardized. Some docs
 	// say: "It is expected to be a comma separated list of
 	// personal data where the first item is the full name of the
 	// user."
 	if i := strings.Index(u.Name, ","); i >= 0 {
 		u.Name = u.Name[:i]
 	}
-	return u, nil
+	return u
+}
+
+func currentGroup() (*Group, error) {
+	return lookupUnixGid(syscall.Getgid())
+}
+
+func lookupGroup(groupname string) (*Group, error) {
+	var grp syscall.Group
+	var result *syscall.Group
+
+	buf := alloc(groupBuffer)
+	defer buf.free()
+	p := syscall.StringBytePtr(groupname)
+
+	err := retryWithBuffer(buf, func() syscall.Errno {
+		syscall.Entersyscall()
+		rv := libc_getgrnam_r(p,
+			&grp,
+			buf.ptr,
+			buf.size,
+			&result)
+		syscall.Exitsyscall()
+		if rv != 0 {
+			return syscall.GetErrno()
+		}
+		return 0
+	})
+	if err != nil {
+		return nil, fmt.Errorf("user: lookup groupname %s: %v", groupname, err)
+	}
+	if result == nil {
+		return nil, UnknownGroupError(groupname)
+	}
+	return buildGroup(&grp), nil
+}
+
+func lookupGroupId(gid string) (*Group, error) {
+	i, e := strconv.Atoi(gid)
+	if e != nil {
+		return nil, e
+	}
+	return lookupUnixGid(i)
+}
+
+func lookupUnixGid(gid int) (*Group, error) {
+	var grp syscall.Group
+	var result *syscall.Group
+
+	buf := alloc(groupBuffer)
+	defer buf.free()
+
+	err := retryWithBuffer(buf, func() syscall.Errno {
+		syscall.Entersyscall()
+		rv := libc_getgrgid_r(syscall.Gid_t(gid),
+			&grp,
+			buf.ptr,
+			buf.size,
+			&result)
+		syscall.Exitsyscall()
+		if rv != 0 {
+			return syscall.GetErrno()
+		}
+		return 0
+	})
+	if err != nil {
+		return nil, fmt.Errorf("user: lookup groupid %d: %v", gid, err)
+	}
+	if result == nil {
+		return nil, UnknownGroupIdError(strconv.Itoa(gid))
+	}
+	return buildGroup(&grp), nil
+}
+
+func buildGroup(grp *syscall.Group) *Group {
+	g := &Group{
+		Gid:  strconv.Itoa(int(grp.Gr_gid)),
+		Name: bytePtrToString((*byte)(unsafe.Pointer(grp.Gr_name))),
+	}
+	return g
+}
+
+type bufferKind int
+
+const (
+	userBuffer  = bufferKind(syscall.SC_GETPW_R_SIZE_MAX)
+	groupBuffer = bufferKind(syscall.SC_GETGR_R_SIZE_MAX)
+)
+
+func (k bufferKind) initialSize() syscall.Size_t {
+	sz, _ := syscall.Sysconf(int(k))
+	if sz == -1 {
+		// DragonFly and FreeBSD do not have _SC_GETPW_R_SIZE_MAX.
+		// Additionally, not all Linux systems have it, either. For
+		// example, the musl libc returns -1.
+		return 1024
+	}
+	if !isSizeReasonable(int64(sz)) {
+		// Truncate.  If this truly isn't enough, retryWithBuffer will error on the first run.
+		return maxBufferSize
+	}
+	return syscall.Size_t(sz)
+}
+
+type memBuffer struct {
+	ptr  *byte
+	size syscall.Size_t
+}
+
+func alloc(kind bufferKind) *memBuffer {
+	sz := kind.initialSize()
+	b := make([]byte, sz)
+	return &memBuffer{
+		ptr:  &b[0],
+		size: sz,
+	}
+}
+
+func (mb *memBuffer) resize(newSize syscall.Size_t) {
+	b := make([]byte, newSize)
+	mb.ptr = &b[0]
+	mb.size = newSize
+}
+
+func (mb *memBuffer) free() {
+	mb.ptr = nil
+}
+
+// retryWithBuffer repeatedly calls f(), increasing the size of the
+// buffer each time, until f succeeds, fails with a non-ERANGE error,
+// or the buffer exceeds a reasonable limit.
+func retryWithBuffer(buf *memBuffer, f func() syscall.Errno) error {
+	for {
+		errno := f()
+		if errno == 0 {
+			return nil
+		} else if errno != syscall.ERANGE {
+			return errno
+		}
+		newSize := buf.size * 2
+		if !isSizeReasonable(int64(newSize)) {
+			return fmt.Errorf("internal buffer exceeds %d bytes", maxBufferSize)
+		}
+		buf.resize(newSize)
+	}
+}
+
+const maxBufferSize = 1 << 20
+
+func isSizeReasonable(sz int64) bool {
+	return sz > 0 && sz <= maxBufferSize
 }
diff --git a/libgo/go/os/user/lookup_windows.go b/libgo/go/os/user/lookup_windows.go
index 99c325ff010..4e36a5c2bfa 100644
--- a/libgo/go/os/user/lookup_windows.go
+++ b/libgo/go/os/user/lookup_windows.go
@@ -5,11 +5,16 @@
 package user
 
 import (
+	"errors"
 	"fmt"
 	"syscall"
 	"unsafe"
 )
 
+func init() {
+	groupImplemented = false
+}
+
 func isDomainJoined() (bool, error) {
 	var domain *uint16
 	var status uint32
@@ -61,7 +66,7 @@ func lookupFullName(domain, username, domainAndUser string) (string, error) {
 	if err == nil {
 		return name, nil
 	}
-	// domain worked neigher as a domain nor as a server
+	// domain worked neither as a domain nor as a server
 	// could be domain server unavailable
 	// pretend username is fullname
 	return username, nil
@@ -129,7 +134,7 @@ func newUserFromSid(usid *syscall.SID) (*User, error) {
 	return newUser(usid, gid, dir)
 }
 
-func lookup(username string) (*User, error) {
+func lookupUser(username string) (*User, error) {
 	sid, _, t, e := syscall.LookupSID("", username)
 	if e != nil {
 		return nil, e
@@ -140,10 +145,22 @@ func lookup(username string) (*User, error) {
 	return newUserFromSid(sid)
 }
 
-func lookupId(uid string) (*User, error) {
+func lookupUserId(uid string) (*User, error) {
 	sid, e := syscall.StringToSid(uid)
 	if e != nil {
 		return nil, e
 	}
 	return newUserFromSid(sid)
 }
+
+func lookupGroup(groupname string) (*Group, error) {
+	return nil, errors.New("user: LookupGroup not implemented on windows")
+}
+
+func lookupGroupId(string) (*Group, error) {
+	return nil, errors.New("user: LookupGroupId not implemented on windows")
+}
+
+func listGroups(*User) ([]string, error) {
+	return nil, errors.New("user: GroupIds not implemented on windows")
+}
diff --git a/libgo/go/os/user/user.go b/libgo/go/os/user/user.go
index e8680fe5465..7b44397afb3 100644
--- a/libgo/go/os/user/user.go
+++ b/libgo/go/os/user/user.go
@@ -9,23 +9,35 @@ import (
 	"strconv"
 )
 
-var implemented = true // set to false by lookup_stubs.go's init
+var (
+	userImplemented  = true // set to false by lookup_stubs.go's init
+	groupImplemented = true // set to false by lookup_stubs.go's init
+)
 
 // User represents a user account.
 //
-// On posix systems Uid and Gid contain a decimal number
+// On POSIX systems Uid and Gid contain a decimal number
 // representing uid and gid. On windows Uid and Gid
 // contain security identifier (SID) in a string format.
 // On Plan 9, Uid, Gid, Username, and Name will be the
 // contents of /dev/user.
 type User struct {
-	Uid      string // user id
-	Gid      string // primary group id
+	Uid      string // user ID
+	Gid      string // primary group ID
 	Username string
 	Name     string
 	HomeDir  string
 }
 
+// Group represents a grouping of users.
+//
+// On POSIX systems Gid contains a decimal number
+// representing the group ID.
+type Group struct {
+	Gid  string // group ID
+	Name string // group name
+}
+
 // UnknownUserIdError is returned by LookupId when
 // a user cannot be found.
 type UnknownUserIdError int
@@ -41,3 +53,19 @@ type UnknownUserError string
 func (e UnknownUserError) Error() string {
 	return "user: unknown user " + string(e)
 }
+
+// UnknownGroupIdError is returned by LookupGroupId when
+// a group cannot be found.
+type UnknownGroupIdError string
+
+func (e UnknownGroupIdError) Error() string {
+	return "group: unknown groupid " + string(e)
+}
+
+// UnknownGroupError is returned by LookupGroup when
+// a group cannot be found.
+type UnknownGroupError string
+
+func (e UnknownGroupError) Error() string {
+	return "group: unknown group " + string(e)
+}
diff --git a/libgo/go/os/user/user_test.go b/libgo/go/os/user/user_test.go
index 9d9420e8090..9d8d94d8dae 100644
--- a/libgo/go/os/user/user_test.go
+++ b/libgo/go/os/user/user_test.go
@@ -9,18 +9,19 @@ import (
 	"testing"
 )
 
-func check(t *testing.T) {
-	if !implemented {
+func checkUser(t *testing.T) {
+	if !userImplemented {
 		t.Skip("user: not implemented; skipping tests")
 	}
 }
 
 func TestCurrent(t *testing.T) {
-	check(t)
-
+	if runtime.GOOS == "android" {
+		t.Skipf("skipping on %s", runtime.GOOS)
+	}
 	u, err := Current()
 	if err != nil {
-		t.Fatalf("Current: %v", err)
+		t.Fatalf("Current: %v (got %#v)", err, u)
 	}
 	if u.HomeDir == "" {
 		t.Errorf("didn't get a HomeDir")
@@ -53,7 +54,7 @@ func compare(t *testing.T, want, got *User) {
 }
 
 func TestLookup(t *testing.T) {
-	check(t)
+	checkUser(t)
 
 	if runtime.GOOS == "plan9" {
 		t.Skipf("Lookup not implemented on %q", runtime.GOOS)
@@ -71,7 +72,7 @@ func TestLookup(t *testing.T) {
 }
 
 func TestLookupId(t *testing.T) {
-	check(t)
+	checkUser(t)
 
 	if runtime.GOOS == "plan9" {
 		t.Skipf("LookupId not implemented on %q", runtime.GOOS)
@@ -87,3 +88,64 @@ func TestLookupId(t *testing.T) {
 	}
 	compare(t, want, got)
 }
+
+func checkGroup(t *testing.T) {
+	if !groupImplemented {
+		t.Skip("user: group not implemented; skipping test")
+	}
+}
+
+func TestLookupGroup(t *testing.T) {
+	checkGroup(t)
+	user, err := Current()
+	if err != nil {
+		t.Fatalf("Current(): %v", err)
+	}
+
+	g1, err := LookupGroupId(user.Gid)
+	if err != nil {
+		// NOTE(rsc): Maybe the group isn't defined. That's fine.
+		// On my OS X laptop, rsc logs in with group 5000 even
+		// though there's no name for group 5000. Such is Unix.
+		t.Logf("LookupGroupId(%q): %v", user.Gid, err)
+		return
+	}
+	if g1.Gid != user.Gid {
+		t.Errorf("LookupGroupId(%q).Gid = %s; want %s", user.Gid, g1.Gid, user.Gid)
+	}
+
+	g2, err := LookupGroup(g1.Name)
+	if err != nil {
+		t.Fatalf("LookupGroup(%q): %v", g1.Name, err)
+	}
+	if g1.Gid != g2.Gid || g1.Name != g2.Name {
+		t.Errorf("LookupGroup(%q) = %+v; want %+v", g1.Name, g2, g1)
+	}
+}
+
+func TestGroupIds(t *testing.T) {
+	checkGroup(t)
+	if runtime.GOOS == "solaris" {
+		t.Skip("skipping GroupIds, see golang.org/issue/14709")
+	}
+	user, err := Current()
+	if err != nil {
+		t.Fatalf("Current(): %v", err)
+	}
+	gids, err := user.GroupIds()
+	if err != nil {
+		t.Fatalf("%+v.GroupIds(): %v", user, err)
+	}
+	if !containsID(gids, user.Gid) {
+		t.Errorf("%+v.GroupIds() = %v; does not contain user GID %s", user, gids, user.Gid)
+	}
+}
+
+func containsID(ids []string, id string) bool {
+	for _, x := range ids {
+		if x == id {
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/os/wait_unimp.go b/libgo/go/os/wait_unimp.go
new file mode 100644
index 00000000000..7059e59ab24
--- /dev/null
+++ b/libgo/go/os/wait_unimp.go
@@ -0,0 +1,16 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build dragonfly nacl netbsd openbsd solaris
+
+package os
+
+// blockUntilWaitable attempts to block until a call to p.Wait will
+// succeed immediately, and returns whether it has done so.
+// It does not actually call p.Wait.
+// This version is used on systems that do not implement waitid,
+// or where we have not implemented it yet.
+func (p *Process) blockUntilWaitable() (bool, error) {
+	return false, nil
+}
diff --git a/libgo/go/os/wait_wait6.go b/libgo/go/os/wait_wait6.go
new file mode 100644
index 00000000000..7f4780ae2d0
--- /dev/null
+++ b/libgo/go/os/wait_wait6.go
@@ -0,0 +1,40 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build freebsd
+
+package os
+
+import (
+	"runtime"
+	"syscall"
+)
+
+const _P_PID = 0
+
+// blockUntilWaitable attempts to block until a call to p.Wait will
+// succeed immediately, and returns whether it has done so.
+// It does not actually call p.Wait.
+func (p *Process) blockUntilWaitable() (bool, error) {
+	var errno syscall.Errno
+	// The arguments on 32-bit FreeBSD look like the following:
+	// - freebsd32_wait6_args{ idtype, id1, id2, status, options, wrusage, info } or
+	// - freebsd32_wait6_args{ idtype, pad, id1, id2, status, options, wrusage, info } when PAD64_REQUIRED=1 on ARM, MIPS or PowerPC
+	if runtime.GOARCH == "386" {
+		_, _, errno = syscall.Syscall9(syscall.SYS_WAIT6, _P_PID, uintptr(p.Pid), 0, 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0, 0, 0)
+	} else if runtime.GOARCH == "arm" {
+		_, _, errno = syscall.Syscall9(syscall.SYS_WAIT6, _P_PID, 0, uintptr(p.Pid), 0, 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0, 0)
+	} else {
+		_, _, errno = syscall.Syscall6(syscall.SYS_WAIT6, _P_PID, uintptr(p.Pid), 0, syscall.WEXITED|syscall.WNOWAIT, 0, 0)
+	}
+	if errno != 0 {
+		// The wait6 system call is supported only on FreeBSD
+		// 9.3 and above, so it may return an ENOSYS error.
+		if errno == syscall.ENOSYS {
+			return false, nil
+		}
+		return false, NewSyscallError("wait6", errno)
+	}
+	return true, nil
+}
diff --git a/libgo/go/os/wait_waitid.go b/libgo/go/os/wait_waitid.go
new file mode 100644
index 00000000000..5dbd7f97662
--- /dev/null
+++ b/libgo/go/os/wait_waitid.go
@@ -0,0 +1,34 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin linux
+
+package os
+
+import (
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+const _P_PID = 1
+
+// blockUntilWaitable attempts to block until a call to p.Wait will
+// succeed immediately, and returns whether it has done so.
+// It does not actually call p.Wait.
+func (p *Process) blockUntilWaitable() (bool, error) {
+	// The waitid system call expects a pointer to a siginfo_t,
+	// which is 128 bytes on all GNU/Linux systems.
+	// On Darwin, it requires greater than or equal to 64 bytes
+	// for darwin/{386,arm} and 104 bytes for darwin/amd64.
+	// We don't care about the values it returns.
+	var siginfo [128]byte
+	psig := &siginfo[0]
+	_, _, e := syscall.Syscall6(syscall.SYS_WAITID, _P_PID, uintptr(p.Pid), uintptr(unsafe.Pointer(psig)), syscall.WEXITED|syscall.WNOWAIT, 0, 0)
+	runtime.KeepAlive(psig)
+	if e != 0 {
+		return false, NewSyscallError("waitid", e)
+	}
+	return true, nil
+}
diff --git a/libgo/go/path/example_test.go b/libgo/go/path/example_test.go
index ca18b32305e..88b76557f2b 100644
--- a/libgo/go/path/example_test.go
+++ b/libgo/go/path/example_test.go
@@ -56,7 +56,14 @@ func ExampleIsAbs() {
 
 func ExampleJoin() {
 	fmt.Println(path.Join("a", "b", "c"))
-	// Output: a/b/c
+	fmt.Println(path.Join("a", "b/c"))
+	fmt.Println(path.Join("a/b", "c"))
+	fmt.Println(path.Join("a/b", "/c"))
+	// Output:
+	// a/b/c
+	// a/b/c
+	// a/b/c
+	// a/b/c
 }
 
 func ExampleSplit() {
diff --git a/libgo/go/path/filepath/example_unix_test.go b/libgo/go/path/filepath/example_unix_test.go
index 893be1b1988..cd8233ceb6a 100644
--- a/libgo/go/path/filepath/example_unix_test.go
+++ b/libgo/go/path/filepath/example_unix_test.go
@@ -65,3 +65,17 @@ func ExampleSplit() {
 	// 	dir: "/usr/local//"
 	// 	file: "go"
 }
+
+func ExampleJoin() {
+	fmt.Println("On Unix:")
+	fmt.Println(filepath.Join("a", "b", "c"))
+	fmt.Println(filepath.Join("a", "b/c"))
+	fmt.Println(filepath.Join("a/b", "c"))
+	fmt.Println(filepath.Join("a/b", "/c"))
+	// Output:
+	// On Unix:
+	// a/b/c
+	// a/b/c
+	// a/b/c
+	// a/b/c
+}
diff --git a/libgo/go/path/filepath/export_windows_test.go b/libgo/go/path/filepath/export_windows_test.go
new file mode 100644
index 00000000000..8ca007f70aa
--- /dev/null
+++ b/libgo/go/path/filepath/export_windows_test.go
@@ -0,0 +1,7 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package filepath
+
+var ToNorm = toNorm
diff --git a/libgo/go/path/filepath/match.go b/libgo/go/path/filepath/match.go
index 89f16de355e..9fa68f578d0 100644
--- a/libgo/go/path/filepath/match.go
+++ b/libgo/go/path/filepath/match.go
@@ -49,7 +49,7 @@ Pattern:
 		star, chunk, pattern = scanChunk(pattern)
 		if star && chunk == "" {
 			// Trailing * matches rest of string unless it has a /.
-			return strings.Index(name, string(Separator)) < 0, nil
+			return !strings.Contains(name, string(Separator)), nil
 		}
 		// Look for match at current position.
 		t, ok, err := matchChunk(chunk, name)
@@ -240,19 +240,21 @@ func Glob(pattern string) (matches []string, err error) {
 	}
 
 	dir, file := Split(pattern)
-	switch dir {
-	case "":
-		dir = "."
-	case string(Separator):
-		// nothing
-	default:
-		dir = dir[0 : len(dir)-1] // chop off trailing separator
+	if runtime.GOOS == "windows" {
+		dir = cleanGlobPathWindows(dir)
+	} else {
+		dir = cleanGlobPath(dir)
 	}
 
 	if !hasMeta(dir) {
 		return glob(dir, file, nil)
 	}
 
+	// Prevent infinite recursion. See issue 15879.
+	if dir == pattern {
+		return nil, ErrBadPattern
+	}
+
 	var m []string
 	m, err = Glob(dir)
 	if err != nil {
@@ -267,6 +269,35 @@ func Glob(pattern string) (matches []string, err error) {
 	return
 }
 
+// cleanGlobPath prepares path for glob matching.
+func cleanGlobPath(path string) string {
+	switch path {
+	case "":
+		return "."
+	case string(Separator):
+		// do nothing to the path
+		return path
+	default:
+		return path[0 : len(path)-1] // chop off trailing separator
+	}
+}
+
+// cleanGlobPathWindows is windows version of cleanGlobPath.
+func cleanGlobPathWindows(path string) string {
+	vollen := volumeNameLen(path)
+	switch {
+	case path == "":
+		return "."
+	case vollen+1 == len(path) && os.IsPathSeparator(path[len(path)-1]): // /, \, C:\ and C:/
+		// do nothing to the path
+		return path
+	case vollen == len(path) && len(path) == 2: // C:
+		return path + "." // convert C: into C:.
+	default:
+		return path[0 : len(path)-1] // chop off trailing separator
+	}
+}
+
 // glob searches for files matching pattern in the directory dir
 // and appends them to matches. If the directory cannot be
 // opened, it returns the existing matches. New matches are
@@ -305,5 +336,5 @@ func glob(dir, pattern string, matches []string) (m []string, e error) {
 // recognized by Match.
 func hasMeta(path string) bool {
 	// TODO(niemeyer): Should other magic characters be added here?
-	return strings.IndexAny(path, "*?[") >= 0
+	return strings.ContainsAny(path, "*?[")
 }
diff --git a/libgo/go/path/filepath/match_test.go b/libgo/go/path/filepath/match_test.go
index 209c67f30fd..102eb1ce092 100644
--- a/libgo/go/path/filepath/match_test.go
+++ b/libgo/go/path/filepath/match_test.go
@@ -5,10 +5,12 @@
 package filepath_test
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	. "path/filepath"
 	"runtime"
+	"sort"
 	"strings"
 	"testing"
 )
@@ -88,7 +90,7 @@ func TestMatch(t *testing.T) {
 		pattern := tt.pattern
 		s := tt.s
 		if runtime.GOOS == "windows" {
-			if strings.Index(pattern, "\\") >= 0 {
+			if strings.Contains(pattern, "\\") {
 				// no escape allowed on windows.
 				continue
 			}
@@ -158,6 +160,12 @@ func TestGlobError(t *testing.T) {
 	}
 }
 
+func TestGlobUNC(t *testing.T) {
+	// Just make sure this runs without crashing for now.
+	// See issue 15879.
+	Glob(`\\?\C:\*`)
+}
+
 var globSymlinkTests = []struct {
 	path, dest string
 	brokenLink bool
@@ -210,3 +218,164 @@ func TestGlobSymlink(t *testing.T) {
 		}
 	}
 }
+
+type globTest struct {
+	pattern string
+	matches []string
+}
+
+func (test *globTest) buildWant(root string) []string {
+	want := make([]string, 0)
+	for _, m := range test.matches {
+		want = append(want, root+FromSlash(m))
+	}
+	sort.Strings(want)
+	return want
+}
+
+func (test *globTest) globAbs(root, rootPattern string) error {
+	p := FromSlash(rootPattern + `\` + test.pattern)
+	have, err := Glob(p)
+	if err != nil {
+		return err
+	}
+	sort.Strings(have)
+	want := test.buildWant(root + `\`)
+	if strings.Join(want, "_") == strings.Join(have, "_") {
+		return nil
+	}
+	return fmt.Errorf("Glob(%q) returns %q, but %q expected", p, have, want)
+}
+
+func (test *globTest) globRel(root string) error {
+	p := root + FromSlash(test.pattern)
+	have, err := Glob(p)
+	if err != nil {
+		return err
+	}
+	sort.Strings(have)
+	want := test.buildWant(root)
+	if strings.Join(want, "_") == strings.Join(have, "_") {
+		return nil
+	}
+	// try also matching version without root prefix
+	wantWithNoRoot := test.buildWant("")
+	if strings.Join(wantWithNoRoot, "_") == strings.Join(have, "_") {
+		return nil
+	}
+	return fmt.Errorf("Glob(%q) returns %q, but %q expected", p, have, want)
+}
+
+func TestWindowsGlob(t *testing.T) {
+	if runtime.GOOS != "windows" {
+		t.Skipf("skipping windows specific test")
+	}
+
+	tmpDir, err := ioutil.TempDir("", "TestWindowsGlob")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	// /tmp may itself be a symlink
+	tmpDir, err = EvalSymlinks(tmpDir)
+	if err != nil {
+		t.Fatal("eval symlink for tmp dir:", err)
+	}
+
+	if len(tmpDir) < 3 {
+		t.Fatalf("tmpDir path %q is too short", tmpDir)
+	}
+	if tmpDir[1] != ':' {
+		t.Fatalf("tmpDir path %q must have drive letter in it", tmpDir)
+	}
+
+	dirs := []string{
+		"a",
+		"b",
+		"dir/d/bin",
+	}
+	files := []string{
+		"dir/d/bin/git.exe",
+	}
+	for _, dir := range dirs {
+		err := os.MkdirAll(Join(tmpDir, dir), 0777)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, file := range files {
+		err := ioutil.WriteFile(Join(tmpDir, file), nil, 0666)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	tests := []globTest{
+		{"a", []string{"a"}},
+		{"b", []string{"b"}},
+		{"c", []string{}},
+		{"*", []string{"a", "b", "dir"}},
+		{"d*", []string{"dir"}},
+		{"*i*", []string{"dir"}},
+		{"*r", []string{"dir"}},
+		{"?ir", []string{"dir"}},
+		{"?r", []string{}},
+		{"d*/*/bin/git.exe", []string{"dir/d/bin/git.exe"}},
+	}
+
+	// test absolute paths
+	for _, test := range tests {
+		var p string
+		err = test.globAbs(tmpDir, tmpDir)
+		if err != nil {
+			t.Error(err)
+		}
+		// test C:\*Documents and Settings\...
+		p = tmpDir
+		p = strings.Replace(p, `:\`, `:\*`, 1)
+		err = test.globAbs(tmpDir, p)
+		if err != nil {
+			t.Error(err)
+		}
+		// test C:\Documents and Settings*\...
+		p = tmpDir
+		p = strings.Replace(p, `:\`, `:`, 1)
+		p = strings.Replace(p, `\`, `*\`, 1)
+		p = strings.Replace(p, `:`, `:\`, 1)
+		err = test.globAbs(tmpDir, p)
+		if err != nil {
+			t.Error(err)
+		}
+	}
+
+	// test relative paths
+	wd, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = os.Chdir(tmpDir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() {
+		err := os.Chdir(wd)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}()
+	for _, test := range tests {
+		err := test.globRel("")
+		if err != nil {
+			t.Error(err)
+		}
+		err = test.globRel(`.\`)
+		if err != nil {
+			t.Error(err)
+		}
+		err = test.globRel(tmpDir[:2]) // C:
+		if err != nil {
+			t.Error(err)
+		}
+	}
+}
diff --git a/libgo/go/path/filepath/path.go b/libgo/go/path/filepath/path.go
index dd6f3e7a994..0dc559cdd67 100644
--- a/libgo/go/path/filepath/path.go
+++ b/libgo/go/path/filepath/path.go
@@ -4,9 +4,6 @@
 
 // Package filepath implements utility routines for manipulating filename paths
 // in a way compatible with the target operating system-defined file paths.
-//
-// Functions in this package replace any occurrences of the slash ('/') character
-// with os.PathSeparator when returning paths unless otherwise specified.
 package filepath
 
 import (
@@ -61,7 +58,7 @@ const (
 )
 
 // Clean returns the shortest path name equivalent to path
-// by purely lexical processing.  It applies the following rules
+// by purely lexical processing. It applies the following rules
 // iteratively until no further processing can be done:
 //
 //	1. Replace multiple Separator elements with a single one.
@@ -75,12 +72,14 @@ const (
 // The returned path ends in a slash only if it represents a root directory,
 // such as "/" on Unix or `C:\` on Windows.
 //
+// Finally, any occurrences of slash are replaced by Separator.
+//
 // If the result of this process is an empty string, Clean
 // returns the string ".".
 //
 // See also Rob Pike, ``Lexical File Names in Plan 9 or
 // Getting Dot-Dot Right,''
-// http://plan9.bell-labs.com/sys/doc/lexnames.html
+// https://9p.io/sys/doc/lexnames.html
 func Clean(path string) string {
 	originalPath := path
 	volLen := volumeNameLen(path)
@@ -198,7 +197,7 @@ func Split(path string) (dir, file string) {
 }
 
 // Join joins any number of path elements into a single path, adding
-// a Separator if necessary. The result is Cleaned, in particular
+// a Separator if necessary. Join calls Clean on the result; in particular,
 // all empty strings are ignored.
 // On Windows, the result is a UNC path if and only if the first path
 // element is a UNC path.
@@ -223,14 +222,16 @@ func Ext(path string) string {
 // links.
 // If path is relative the result will be relative to the current directory,
 // unless one of the components is an absolute symbolic link.
+// EvalSymlinks calls Clean on the result.
 func EvalSymlinks(path string) (string, error) {
 	return evalSymlinks(path)
 }
 
 // Abs returns an absolute representation of path.
 // If the path is not absolute it will be joined with the current
-// working directory to turn it into an absolute path.  The absolute
+// working directory to turn it into an absolute path. The absolute
 // path name for a given file is not guaranteed to be unique.
+// Abs calls Clean on the result.
 func Abs(path string) (string, error) {
 	return abs(path)
 }
@@ -253,6 +254,7 @@ func unixAbs(path string) (string, error) {
 // even if basepath and targpath share no elements.
 // An error is returned if targpath can't be made relative to basepath or if
 // knowing the current working directory would be necessary to compute it.
+// Rel calls Clean on the result.
 func Rel(basepath, targpath string) (string, error) {
 	baseVol := VolumeName(basepath)
 	targVol := VolumeName(targpath)
@@ -442,7 +444,7 @@ func Base(path string) string {
 }
 
 // Dir returns all but the last element of path, typically the path's directory.
-// After dropping the final element, the path is Cleaned and trailing
+// After dropping the final element, Dir calls Clean on the path and trailing
 // slashes are removed.
 // If the path is empty, Dir returns ".".
 // If the path consists entirely of separators, Dir returns a single separator.
diff --git a/libgo/go/path/filepath/path_test.go b/libgo/go/path/filepath/path_test.go
index 10ea795e90e..4d5e3bdcb6d 100644
--- a/libgo/go/path/filepath/path_test.go
+++ b/libgo/go/path/filepath/path_test.go
@@ -452,7 +452,7 @@ func TestWalk(t *testing.T) {
 	checkMarks(t, true)
 	errors = errors[0:0]
 
-	// Test permission errors.  Only possible if we're not root
+	// Test permission errors. Only possible if we're not root
 	// and only on some file systems (AFS, FAT).  To avoid errors during
 	// all.bash on those file systems, skip during go test -short.
 	if os.Getuid() > 0 && !testing.Short() {
@@ -1018,7 +1018,7 @@ func TestAbs(t *testing.T) {
 		vol := filepath.VolumeName(root)
 		var extra []string
 		for _, path := range absTests {
-			if strings.Index(path, "$") != -1 {
+			if strings.Contains(path, "$") {
 				continue
 			}
 			path = vol + path
diff --git a/libgo/go/path/filepath/path_windows.go b/libgo/go/path/filepath/path_windows.go
index ef6e7ca93f4..41c57df7386 100644
--- a/libgo/go/path/filepath/path_windows.go
+++ b/libgo/go/path/filepath/path_windows.go
@@ -121,7 +121,7 @@ func join(elem []string) string {
 // joinNonEmpty is like join, but it assumes that the first element is non-empty.
 func joinNonEmpty(elem []string) string {
 	if len(elem[0]) == 2 && elem[0][1] == ':' {
-		// First element is drive leter without terminating slash.
+		// First element is drive letter without terminating slash.
 		// Keep path relative to current directory on that drive.
 		return Clean(elem[0] + strings.Join(elem[1:], string(Separator)))
 	}
diff --git a/libgo/go/path/filepath/symlink.go b/libgo/go/path/filepath/symlink.go
index bc287c5ecb3..f627a94ddb9 100644
--- a/libgo/go/path/filepath/symlink.go
+++ b/libgo/go/path/filepath/symlink.go
@@ -100,7 +100,7 @@ func walkSymlinks(path string) (string, error) {
 			return "", err
 		}
 		if runtime.GOOS == "windows" {
-			// walkLinks(".", ...) always retuns "." on unix.
+			// walkLinks(".", ...) always returns "." on unix.
 			// But on windows it returns symlink target, if current
 			// directory is a symlink. Stop the walk, if symlink
 			// target is not absolute path, and return "."
diff --git a/libgo/go/path/filepath/symlink_windows.go b/libgo/go/path/filepath/symlink_windows.go
index eb48367ec2b..243352819e0 100644
--- a/libgo/go/path/filepath/symlink_windows.go
+++ b/libgo/go/path/filepath/symlink_windows.go
@@ -5,45 +5,82 @@
 package filepath
 
 import (
+	"strings"
 	"syscall"
 )
 
-func toShort(path string) (string, error) {
-	p, err := syscall.UTF16FromString(path)
+// normVolumeName is like VolumeName, but makes drive letter upper case.
+// result of EvalSymlinks must be unique, so we have
+// EvalSymlinks(`c:\a`) == EvalSymlinks(`C:\a`).
+func normVolumeName(path string) string {
+	volume := VolumeName(path)
+
+	if len(volume) > 2 { // isUNC
+		return volume
+	}
+
+	return strings.ToUpper(volume)
+}
+
+// normBase retruns the last element of path.
+func normBase(path string) (string, error) {
+	p, err := syscall.UTF16PtrFromString(path)
 	if err != nil {
 		return "", err
 	}
-	b := p // GetShortPathName says we can reuse buffer
-	n := uint32(len(b))
-	for {
-		n, err = syscall.GetShortPathName(&p[0], &b[0], uint32(len(b)))
-		if err != nil {
-			return "", err
-		}
-		if n <= uint32(len(b)) {
-			return syscall.UTF16ToString(b[:n]), nil
-		}
-		b = make([]uint16, n)
-	}
-}
 
-func toLong(path string) (string, error) {
-	p, err := syscall.UTF16FromString(path)
+	var data syscall.Win32finddata
+
+	h, err := syscall.FindFirstFile(p, &data)
 	if err != nil {
 		return "", err
 	}
-	b := p // GetLongPathName says we can reuse buffer
-	n := uint32(len(b))
+	syscall.FindClose(h)
+
+	return syscall.UTF16ToString(data.FileName[:]), nil
+}
+
+func toNorm(path string, base func(string) (string, error)) (string, error) {
+	if path == "" {
+		return path, nil
+	}
+
+	path = Clean(path)
+
+	volume := normVolumeName(path)
+	path = path[len(volume):]
+
+	// skip special cases
+	if path == "." || path == `\` {
+		return volume + path, nil
+	}
+
+	var normPath string
+
 	for {
-		n, err = syscall.GetLongPathName(&p[0], &b[0], uint32(len(b)))
+		name, err := base(volume + path)
 		if err != nil {
 			return "", err
 		}
-		if n <= uint32(len(b)) {
-			return syscall.UTF16ToString(b[:n]), nil
+
+		normPath = name + `\` + normPath
+
+		i := strings.LastIndexByte(path, Separator)
+		if i == -1 {
+			break
+		}
+		if i == 0 { // `\Go` or `C:\Go`
+			normPath = `\` + normPath
+
+			break
 		}
-		b = make([]uint16, n)
+
+		path = path[:i]
 	}
+
+	normPath = normPath[:len(normPath)-1] // remove trailing '\'
+
+	return volume + normPath, nil
 }
 
 func evalSymlinks(path string) (string, error) {
@@ -51,20 +88,5 @@ func evalSymlinks(path string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	p, err := toShort(path)
-	if err != nil {
-		return "", err
-	}
-	p, err = toLong(p)
-	if err != nil {
-		return "", err
-	}
-	// syscall.GetLongPathName does not change the case of the drive letter,
-	// but the result of EvalSymlinks must be unique, so we have
-	// EvalSymlinks(`c:\a`) == EvalSymlinks(`C:\a`).
-	// Make drive letter upper case.
-	if len(p) >= 2 && p[1] == ':' && 'a' <= p[0] && p[0] <= 'z' {
-		p = string(p[0]+'A'-'a') + p[1:]
-	}
-	return Clean(p), nil
+	return toNorm(path, normBase)
 }
diff --git a/libgo/go/path/match.go b/libgo/go/path/match.go
index 75dd3b38e7c..8d9aa513b18 100644
--- a/libgo/go/path/match.go
+++ b/libgo/go/path/match.go
@@ -43,7 +43,7 @@ Pattern:
 		star, chunk, pattern = scanChunk(pattern)
 		if star && chunk == "" {
 			// Trailing * matches rest of string unless it has a /.
-			return strings.Index(name, "/") < 0, nil
+			return !strings.Contains(name, "/"), nil
 		}
 		// Look for match at current position.
 		t, ok, err := matchChunk(chunk, name)
diff --git a/libgo/go/path/path.go b/libgo/go/path/path.go
index 01071a9a826..c1d4d8aced3 100644
--- a/libgo/go/path/path.go
+++ b/libgo/go/path/path.go
@@ -48,7 +48,7 @@ func (b *lazybuf) string() string {
 }
 
 // Clean returns the shortest path name equivalent to path
-// by purely lexical processing.  It applies the following rules
+// by purely lexical processing. It applies the following rules
 // iteratively until no further processing can be done:
 //
 //	1. Replace multiple slashes with a single slash.
@@ -65,7 +65,7 @@ func (b *lazybuf) string() string {
 //
 // See also Rob Pike, ``Lexical File Names in Plan 9 or
 // Getting Dot-Dot Right,''
-// http://plan9.bell-labs.com/sys/doc/lexnames.html
+// https://9p.io/sys/doc/lexnames.html
 func Clean(path string) string {
 	if path == "" {
 		return "."
diff --git a/libgo/go/path/path_test.go b/libgo/go/path/path_test.go
index 512d936e457..600ff08797c 100644
--- a/libgo/go/path/path_test.go
+++ b/libgo/go/path/path_test.go
@@ -138,15 +138,9 @@ var jointests = []JoinTest{
 	{[]string{"", ""}, ""},
 }
 
-// join takes a []string and passes it to Join.
-func join(elem []string, args ...string) string {
-	args = elem
-	return Join(args...)
-}
-
 func TestJoin(t *testing.T) {
 	for _, test := range jointests {
-		if p := join(test.elem); p != test.path {
+		if p := Join(test.elem...); p != test.path {
 			t.Errorf("join(%q) = %q, want %q", test.elem, p, test.path)
 		}
 	}
diff --git a/libgo/go/reflect/all_test.go b/libgo/go/reflect/all_test.go
index b8e7cd883cb..7045e448ea3 100644
--- a/libgo/go/reflect/all_test.go
+++ b/libgo/go/reflect/all_test.go
@@ -21,6 +21,8 @@ import (
 	"sync"
 	"testing"
 	"time"
+	"unicode"
+	"unicode/utf8"
 	"unsafe"
 )
 
@@ -44,16 +46,12 @@ type pair struct {
 	s string
 }
 
-func isDigit(c uint8) bool { return '0' <= c && c <= '9' }
-
 func assert(t *testing.T, s, want string) {
 	if s != want {
 		t.Errorf("have %#q want %#q", s, want)
 	}
 }
 
-func typestring(i interface{}) string { return TypeOf(i).String() }
-
 var typeTests = []pair{
 	{struct{ x int }{}, "int"},
 	{struct{ x int8 }{}, "int8"},
@@ -1891,32 +1889,6 @@ type Tbigp [2]uintptr
 
 func (p *Tbigp) M(x int, b byte) (byte, int) { return b, x + int(p[0]) + int(p[1]) }
 
-// Again, with an unexported method.
-
-type tsmallv byte
-
-func (v tsmallv) m(x int, b byte) (byte, int) { return b, x + int(v) }
-
-type tsmallp byte
-
-func (p *tsmallp) m(x int, b byte) (byte, int) { return b, x + int(*p) }
-
-type twordv uintptr
-
-func (v twordv) m(x int, b byte) (byte, int) { return b, x + int(v) }
-
-type twordp uintptr
-
-func (p *twordp) m(x int, b byte) (byte, int) { return b, x + int(*p) }
-
-type tbigv [2]uintptr
-
-func (v tbigv) m(x int, b byte) (byte, int) { return b, x + int(v[0]) + int(v[1]) }
-
-type tbigp [2]uintptr
-
-func (p *tbigp) m(x int, b byte) (byte, int) { return b, x + int(p[0]) + int(p[1]) }
-
 type tinter interface {
 	m(int, byte) (byte, int)
 }
@@ -1960,7 +1932,6 @@ func TestMethod5(t *testing.T) {
 	}
 
 	var TinterType = TypeOf(new(Tinter)).Elem()
-	var tinterType = TypeOf(new(tinter)).Elem()
 
 	CheckI := func(name string, i interface{}, inc int) {
 		v := ValueOf(i)
@@ -2002,39 +1973,6 @@ func TestMethod5(t *testing.T) {
 	CheckI("t1", t1, 40)
 	CheckI("&t1", &t1, 40)
 
-	methodShouldPanic := func(name string, i interface{}) {
-		v := ValueOf(i)
-		m := v.Method(0)
-		shouldPanic(func() { m.Call([]Value{ValueOf(1000), ValueOf(byte(99))}) })
-		shouldPanic(func() { m.Interface() })
-
-		v = v.Convert(tinterType)
-		m = v.Method(0)
-		shouldPanic(func() { m.Call([]Value{ValueOf(1000), ValueOf(byte(99))}) })
-		shouldPanic(func() { m.Interface() })
-	}
-
-	_sv := tsmallv(1)
-	methodShouldPanic("_sv", _sv)
-	methodShouldPanic("&_sv", &_sv)
-
-	_sp := tsmallp(2)
-	methodShouldPanic("&_sp", &_sp)
-
-	_wv := twordv(3)
-	methodShouldPanic("_wv", _wv)
-	methodShouldPanic("&_wv", &_wv)
-
-	_wp := twordp(4)
-	methodShouldPanic("&_wp", &_wp)
-
-	_bv := tbigv([2]uintptr{5, 6})
-	methodShouldPanic("_bv", _bv)
-	methodShouldPanic("&_bv", &_bv)
-
-	_bp := tbigp([2]uintptr{7, 8})
-	methodShouldPanic("&_bp", &_bp)
-
 	var tnil Tinter
 	vnil := ValueOf(&tnil).Elem()
 	shouldPanic(func() { vnil.Method(0) })
@@ -2323,6 +2261,8 @@ func TestImportPath(t *testing.T) {
 		{TypeOf((*int64)(nil)), ""},
 		{TypeOf(map[string]int{}), ""},
 		{TypeOf((*error)(nil)).Elem(), ""},
+		{TypeOf((*Point)(nil)), ""},
+		{TypeOf((*Point)(nil)).Elem(), "reflect_test"},
 	}
 	for _, test := range tests {
 		if path := test.t.PkgPath(); path != test.path {
@@ -2331,6 +2271,33 @@ func TestImportPath(t *testing.T) {
 	}
 }
 
+func TestFieldPkgPath(t *testing.T) {
+	typ := TypeOf(struct {
+		Exported   string
+		unexported string
+		OtherPkgFields
+	}{})
+	for _, test := range []struct {
+		index     []int
+		pkgPath   string
+		anonymous bool
+	}{
+		{[]int{0}, "", false},             // Exported
+		{[]int{1}, "reflect_test", false}, // unexported
+		{[]int{2}, "", true},              // OtherPkgFields
+		{[]int{2, 0}, "", false},          // OtherExported
+		{[]int{2, 1}, "reflect", false},   // otherUnexported
+	} {
+		f := typ.FieldByIndex(test.index)
+		if got, want := f.PkgPath, test.pkgPath; got != want {
+			t.Errorf("Field(%d).PkgPath = %q, want %q", test.index, got, want)
+		}
+		if got, want := f.Anonymous, test.anonymous; got != want {
+			t.Errorf("Field(%d).Anonymous = %v, want %v", test.index, got, want)
+		}
+	}
+}
+
 func TestVariadicType(t *testing.T) {
 	// Test example from Type documentation.
 	var f func(x int, y ...float64)
@@ -2363,14 +2330,14 @@ type outer struct {
 	inner
 }
 
-func (*inner) m() {}
-func (*outer) m() {}
+func (*inner) M() {}
+func (*outer) M() {}
 
 func TestNestedMethods(t *testing.T) {
 	t.Skip("fails on gccgo due to function wrappers")
 	typ := TypeOf((*outer)(nil))
-	if typ.NumMethod() != 1 || typ.Method(0).Func.Pointer() != ValueOf((*outer).m).Pointer() {
-		t.Errorf("Wrong method table for outer: (m=%p)", (*outer).m)
+	if typ.NumMethod() != 1 || typ.Method(0).Func.Pointer() != ValueOf((*outer).M).Pointer() {
+		t.Errorf("Wrong method table for outer: (M=%p)", (*outer).M)
 		for i := 0; i < typ.NumMethod(); i++ {
 			m := typ.Method(i)
 			t.Errorf("\t%d: %s %#x\n", i, m.Name, m.Func.Pointer())
@@ -2378,6 +2345,25 @@ func TestNestedMethods(t *testing.T) {
 	}
 }
 
+type unexp struct{}
+
+func (*unexp) f() (int32, int8) { return 7, 7 }
+func (*unexp) g() (int64, int8) { return 8, 8 }
+
+type unexpI interface {
+	f() (int32, int8)
+}
+
+var unexpi unexpI = new(unexp)
+
+func TestUnexportedMethods(t *testing.T) {
+	typ := TypeOf(unexpi)
+
+	if got := typ.NumMethod(); got != 0 {
+		t.Errorf("NumMethod=%d, want 0 satisfied methods", got)
+	}
+}
+
 type InnerInt struct {
 	X int
 }
@@ -2419,6 +2405,17 @@ func TestEmbeddedMethods(t *testing.T) {
 	}
 }
 
+type FuncDDD func(...interface{}) error
+
+func (f FuncDDD) M() {}
+
+func TestNumMethodOnDDD(t *testing.T) {
+	rv := ValueOf((FuncDDD)(nil))
+	if n := rv.NumMethod(); n != 1 {
+		t.Fatalf("NumMethod()=%d, want 1", n)
+	}
+}
+
 func TestPtrTo(t *testing.T) {
 	var i int
 
@@ -2861,12 +2858,11 @@ func TestUnexported(t *testing.T) {
 	isValid(v.Elem().Field(1))
 	isValid(v.Elem().FieldByName("x"))
 	isValid(v.Elem().FieldByName("y"))
-	isValid(v.Type().Method(0).Func)
 	shouldPanic(func() { v.Elem().Field(0).Interface() })
 	shouldPanic(func() { v.Elem().Field(1).Interface() })
 	shouldPanic(func() { v.Elem().FieldByName("x").Interface() })
 	shouldPanic(func() { v.Elem().FieldByName("y").Interface() })
-	shouldPanic(func() { v.Type().Method(0).Func.Interface() })
+	shouldPanic(func() { v.Type().Method(0) })
 }
 
 func TestSetPanic(t *testing.T) {
@@ -3846,6 +3842,9 @@ func TestSliceOf(t *testing.T) {
 	// check construction and use of type not in binary
 	type T int
 	st := SliceOf(TypeOf(T(1)))
+	if got, want := st.String(), "[]reflect_test.T"; got != want {
+		t.Errorf("SliceOf(T(1)).String()=%q, want %q", got, want)
+	}
 	v := MakeSlice(st, 10, 10)
 	runtime.GC()
 	for i := 0; i < v.Len(); i++ {
@@ -3910,6 +3909,591 @@ func TestSliceOfGC(t *testing.T) {
 	}
 }
 
+func TestStructOf(t *testing.T) {
+	// check construction and use of type not in binary
+	fields := []StructField{
+		StructField{
+			Name: "S",
+			Tag:  "s",
+			Type: TypeOf(""),
+		},
+		StructField{
+			Name: "X",
+			Tag:  "x",
+			Type: TypeOf(byte(0)),
+		},
+		StructField{
+			Name: "Y",
+			Type: TypeOf(uint64(0)),
+		},
+		StructField{
+			Name: "Z",
+			Type: TypeOf([3]uint16{}),
+		},
+	}
+
+	st := StructOf(fields)
+	v := New(st).Elem()
+	runtime.GC()
+	v.FieldByName("X").Set(ValueOf(byte(2)))
+	v.FieldByIndex([]int{1}).Set(ValueOf(byte(1)))
+	runtime.GC()
+
+	s := fmt.Sprint(v.Interface())
+	want := `{ 1 0 [0 0 0]}`
+	if s != want {
+		t.Errorf("constructed struct = %s, want %s", s, want)
+	}
+	const stStr = `struct { S string "s"; X uint8 "x"; Y uint64; Z [3]uint16 }`
+	if got, want := st.String(), stStr; got != want {
+		t.Errorf("StructOf(fields).String()=%q, want %q", got, want)
+	}
+
+	// check the size, alignment and field offsets
+	stt := TypeOf(struct {
+		String string
+		X      byte
+		Y      uint64
+		Z      [3]uint16
+	}{})
+	if st.Size() != stt.Size() {
+		t.Errorf("constructed struct size = %v, want %v", st.Size(), stt.Size())
+	}
+	if st.Align() != stt.Align() {
+		t.Errorf("constructed struct align = %v, want %v", st.Align(), stt.Align())
+	}
+	if st.FieldAlign() != stt.FieldAlign() {
+		t.Errorf("constructed struct field align = %v, want %v", st.FieldAlign(), stt.FieldAlign())
+	}
+	for i := 0; i < st.NumField(); i++ {
+		o1 := st.Field(i).Offset
+		o2 := stt.Field(i).Offset
+		if o1 != o2 {
+			t.Errorf("constructed struct field %v offset = %v, want %v", i, o1, o2)
+		}
+	}
+
+	// check duplicate names
+	shouldPanic(func() {
+		StructOf([]StructField{
+			StructField{Name: "string", Type: TypeOf("")},
+			StructField{Name: "string", Type: TypeOf("")},
+		})
+	})
+	shouldPanic(func() {
+		StructOf([]StructField{
+			StructField{Type: TypeOf("")},
+			StructField{Name: "string", Type: TypeOf("")},
+		})
+	})
+	shouldPanic(func() {
+		StructOf([]StructField{
+			StructField{Type: TypeOf("")},
+			StructField{Type: TypeOf("")},
+		})
+	})
+	// check that type already in binary is found
+	checkSameType(t, Zero(StructOf(fields[2:3])).Interface(), struct{ Y uint64 }{})
+}
+
+func TestStructOfExportRules(t *testing.T) {
+	type S1 struct{}
+	type s2 struct{}
+	type ΦType struct{}
+	type φType struct{}
+
+	testPanic := func(i int, mustPanic bool, f func()) {
+		defer func() {
+			err := recover()
+			if err == nil && mustPanic {
+				t.Errorf("test-%d did not panic", i)
+			}
+			if err != nil && !mustPanic {
+				t.Errorf("test-%d panicked: %v\n", i, err)
+			}
+		}()
+		f()
+	}
+
+	for i, test := range []struct {
+		field     StructField
+		mustPanic bool
+		exported  bool
+	}{
+		{
+			field:     StructField{Name: "", Type: TypeOf(S1{})},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf((*S1)(nil))},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf(s2{})},
+			mustPanic: false,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf((*s2)(nil))},
+			mustPanic: false,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf(S1{}), PkgPath: "other/pkg"},
+			mustPanic: true,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf((*S1)(nil)), PkgPath: "other/pkg"},
+			mustPanic: true,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf(s2{}), PkgPath: "other/pkg"},
+			mustPanic: true,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf((*s2)(nil)), PkgPath: "other/pkg"},
+			mustPanic: true,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "S", Type: TypeOf(S1{})},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "S", Type: TypeOf((*S1)(nil))},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "S", Type: TypeOf(s2{})},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "S", Type: TypeOf((*s2)(nil))},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf(S1{})},
+			mustPanic: true,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf((*S1)(nil))},
+			mustPanic: true,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf(s2{})},
+			mustPanic: true,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf((*s2)(nil))},
+			mustPanic: true,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf(S1{}), PkgPath: "other/pkg"},
+			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf((*S1)(nil)), PkgPath: "other/pkg"},
+			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf(s2{}), PkgPath: "other/pkg"},
+			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "s", Type: TypeOf((*s2)(nil)), PkgPath: "other/pkg"},
+			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf(ΦType{})},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf(φType{})},
+			mustPanic: false,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "Φ", Type: TypeOf(0)},
+			mustPanic: false,
+			exported:  true,
+		},
+		{
+			field:     StructField{Name: "φ", Type: TypeOf(0)},
+			mustPanic: false,
+			exported:  false,
+		},
+	} {
+		testPanic(i, test.mustPanic, func() {
+			typ := StructOf([]StructField{test.field})
+			if typ == nil {
+				t.Errorf("test-%d: error creating struct type", i)
+				return
+			}
+			field := typ.Field(0)
+			n := field.Name
+			if n == "" {
+				n = field.Type.Name()
+			}
+			exported := isExported(n)
+			if exported != test.exported {
+				t.Errorf("test-%d: got exported=%v want exported=%v", i, exported, test.exported)
+			}
+		})
+	}
+}
+
+// isExported reports whether name is an exported Go symbol
+// (that is, whether it begins with an upper-case letter).
+//
+func isExported(name string) bool {
+	ch, _ := utf8.DecodeRuneInString(name)
+	return unicode.IsUpper(ch)
+}
+
+func TestStructOfGC(t *testing.T) {
+	type T *uintptr
+	tt := TypeOf(T(nil))
+	fields := []StructField{
+		{Name: "X", Type: tt},
+		{Name: "Y", Type: tt},
+	}
+	st := StructOf(fields)
+
+	const n = 10000
+	var x []interface{}
+	for i := 0; i < n; i++ {
+		v := New(st).Elem()
+		for j := 0; j < v.NumField(); j++ {
+			p := new(uintptr)
+			*p = uintptr(i*n + j)
+			v.Field(j).Set(ValueOf(p).Convert(tt))
+		}
+		x = append(x, v.Interface())
+	}
+	runtime.GC()
+
+	for i, xi := range x {
+		v := ValueOf(xi)
+		for j := 0; j < v.NumField(); j++ {
+			k := v.Field(j).Elem().Interface()
+			if k != uintptr(i*n+j) {
+				t.Errorf("lost x[%d].%c = %d, want %d", i, "XY"[j], k, i*n+j)
+			}
+		}
+	}
+}
+
+func TestStructOfAlg(t *testing.T) {
+	st := StructOf([]StructField{{Name: "X", Tag: "x", Type: TypeOf(int(0))}})
+	v1 := New(st).Elem()
+	v2 := New(st).Elem()
+	if !DeepEqual(v1.Interface(), v1.Interface()) {
+		t.Errorf("constructed struct %v not equal to itself", v1.Interface())
+	}
+	v1.FieldByName("X").Set(ValueOf(int(1)))
+	if i1, i2 := v1.Interface(), v2.Interface(); DeepEqual(i1, i2) {
+		t.Errorf("constructed structs %v and %v should not be equal", i1, i2)
+	}
+
+	st = StructOf([]StructField{{Name: "X", Tag: "x", Type: TypeOf([]int(nil))}})
+	v1 = New(st).Elem()
+	shouldPanic(func() { _ = v1.Interface() == v1.Interface() })
+}
+
+func TestStructOfGenericAlg(t *testing.T) {
+	st1 := StructOf([]StructField{
+		{Name: "X", Tag: "x", Type: TypeOf(int64(0))},
+		{Name: "Y", Type: TypeOf(string(""))},
+	})
+	st := StructOf([]StructField{
+		{Name: "S0", Type: st1},
+		{Name: "S1", Type: st1},
+	})
+
+	for _, table := range []struct {
+		rt  Type
+		idx []int
+	}{
+		{
+			rt:  st,
+			idx: []int{0, 1},
+		},
+		{
+			rt:  st1,
+			idx: []int{1},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf([0]int{})},
+					{Name: "YY", Type: TypeOf("")},
+				},
+			),
+			idx: []int{1},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf([0]int{})},
+					{Name: "YY", Type: TypeOf("")},
+					{Name: "ZZ", Type: TypeOf([2]int{})},
+				},
+			),
+			idx: []int{1},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf([1]int{})},
+					{Name: "YY", Type: TypeOf("")},
+				},
+			),
+			idx: []int{1},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf([1]int{})},
+					{Name: "YY", Type: TypeOf("")},
+					{Name: "ZZ", Type: TypeOf([1]int{})},
+				},
+			),
+			idx: []int{1},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf([2]int{})},
+					{Name: "YY", Type: TypeOf("")},
+					{Name: "ZZ", Type: TypeOf([2]int{})},
+				},
+			),
+			idx: []int{1},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf(int64(0))},
+					{Name: "YY", Type: TypeOf(byte(0))},
+					{Name: "ZZ", Type: TypeOf("")},
+				},
+			),
+			idx: []int{2},
+		},
+		{
+			rt: StructOf(
+				[]StructField{
+					{Name: "XX", Type: TypeOf(int64(0))},
+					{Name: "YY", Type: TypeOf(int64(0))},
+					{Name: "ZZ", Type: TypeOf("")},
+					{Name: "AA", Type: TypeOf([1]int64{})},
+				},
+			),
+			idx: []int{2},
+		},
+	} {
+		v1 := New(table.rt).Elem()
+		v2 := New(table.rt).Elem()
+
+		if !DeepEqual(v1.Interface(), v1.Interface()) {
+			t.Errorf("constructed struct %v not equal to itself", v1.Interface())
+		}
+
+		v1.FieldByIndex(table.idx).Set(ValueOf("abc"))
+		v2.FieldByIndex(table.idx).Set(ValueOf("def"))
+		if i1, i2 := v1.Interface(), v2.Interface(); DeepEqual(i1, i2) {
+			t.Errorf("constructed structs %v and %v should not be equal", i1, i2)
+		}
+
+		abc := "abc"
+		v1.FieldByIndex(table.idx).Set(ValueOf(abc))
+		val := "+" + abc + "-"
+		v2.FieldByIndex(table.idx).Set(ValueOf(val[1:4]))
+		if i1, i2 := v1.Interface(), v2.Interface(); !DeepEqual(i1, i2) {
+			t.Errorf("constructed structs %v and %v should be equal", i1, i2)
+		}
+
+		// Test hash
+		m := MakeMap(MapOf(table.rt, TypeOf(int(0))))
+		m.SetMapIndex(v1, ValueOf(1))
+		if i1, i2 := v1.Interface(), v2.Interface(); !m.MapIndex(v2).IsValid() {
+			t.Errorf("constructed structs %#v and %#v have different hashes", i1, i2)
+		}
+
+		v2.FieldByIndex(table.idx).Set(ValueOf("abc"))
+		if i1, i2 := v1.Interface(), v2.Interface(); !DeepEqual(i1, i2) {
+			t.Errorf("constructed structs %v and %v should be equal", i1, i2)
+		}
+
+		if i1, i2 := v1.Interface(), v2.Interface(); !m.MapIndex(v2).IsValid() {
+			t.Errorf("constructed structs %v and %v have different hashes", i1, i2)
+		}
+	}
+}
+
+/*
+gccgo does not use the same directiface settings as gc.
+
+func TestStructOfDirectIface(t *testing.T) {
+	{
+		type T struct{ X [1]*byte }
+		i1 := Zero(TypeOf(T{})).Interface()
+		v1 := ValueOf(&i1).Elem()
+		p1 := v1.InterfaceData()[1]
+
+		i2 := Zero(StructOf([]StructField{
+			{
+				Name: "X",
+				Type: ArrayOf(1, TypeOf((*int8)(nil))),
+			},
+		})).Interface()
+		v2 := ValueOf(&i2).Elem()
+		p2 := v2.InterfaceData()[1]
+
+		if p1 != 0 {
+			t.Errorf("got p1=%v. want=%v", p1, nil)
+		}
+
+		if p2 != 0 {
+			t.Errorf("got p2=%v. want=%v", p2, nil)
+		}
+	}
+	{
+		type T struct{ X [0]*byte }
+		i1 := Zero(TypeOf(T{})).Interface()
+		v1 := ValueOf(&i1).Elem()
+		p1 := v1.InterfaceData()[1]
+
+		i2 := Zero(StructOf([]StructField{
+			{
+				Name: "X",
+				Type: ArrayOf(0, TypeOf((*int8)(nil))),
+			},
+		})).Interface()
+		v2 := ValueOf(&i2).Elem()
+		p2 := v2.InterfaceData()[1]
+
+		if p1 == 0 {
+			t.Errorf("got p1=%v. want=not-%v", p1, nil)
+		}
+
+		if p2 == 0 {
+			t.Errorf("got p2=%v. want=not-%v", p2, nil)
+		}
+	}
+}
+*/
+
+type StructI int
+
+func (i StructI) Get() int { return int(i) }
+
+type StructIPtr int
+
+func (i *StructIPtr) Get() int { return int(*i) }
+
+/*
+gccgo does not yet support StructOf with methods.
+
+func TestStructOfWithInterface(t *testing.T) {
+	const want = 42
+	type Iface interface {
+		Get() int
+	}
+	for i, table := range []struct {
+		typ  Type
+		val  Value
+		impl bool
+	}{
+		{
+			typ:  TypeOf(StructI(want)),
+			val:  ValueOf(StructI(want)),
+			impl: true,
+		},
+		{
+			typ: PtrTo(TypeOf(StructI(want))),
+			val: ValueOf(func() interface{} {
+				v := StructI(want)
+				return &v
+			}()),
+			impl: true,
+		},
+		{
+			typ: PtrTo(TypeOf(StructIPtr(want))),
+			val: ValueOf(func() interface{} {
+				v := StructIPtr(want)
+				return &v
+			}()),
+			impl: true,
+		},
+		{
+			typ:  TypeOf(StructIPtr(want)),
+			val:  ValueOf(StructIPtr(want)),
+			impl: false,
+		},
+		// {
+		//	typ:  TypeOf((*Iface)(nil)).Elem(), // FIXME(sbinet): fix method.ifn/tfn
+		//	val:  ValueOf(StructI(want)),
+		//	impl: true,
+		// },
+	} {
+		rt := StructOf(
+			[]StructField{
+				{
+					Name:    "",
+					PkgPath: "",
+					Type:    table.typ,
+				},
+			},
+		)
+		rv := New(rt).Elem()
+		rv.Field(0).Set(table.val)
+
+		if _, ok := rv.Interface().(Iface); ok != table.impl {
+			if table.impl {
+				t.Errorf("test-%d: type=%v fails to implement Iface.\n", i, table.typ)
+			} else {
+				t.Errorf("test-%d: type=%v should NOT implement Iface\n", i, table.typ)
+			}
+			continue
+		}
+
+		if !table.impl {
+			continue
+		}
+
+		v := rv.Interface().(Iface).Get()
+		if v != want {
+			t.Errorf("test-%d: x.Get()=%v. want=%v\n", i, v, want)
+		}
+
+		fct := rv.MethodByName("Get")
+		out := fct.Call(nil)
+		if !DeepEqual(out[0].Interface(), want) {
+			t.Errorf("test-%d: x.Get()=%v. want=%v\n", i, out[0].Interface(), want)
+		}
+	}
+}
+*/
+
 func TestChanOf(t *testing.T) {
 	// check construction and use of type not in binary
 	type T string
@@ -4116,7 +4700,7 @@ func TestFuncOf(t *testing.T) {
 		if len(args) != 1 {
 			t.Errorf("args == %v, want exactly one arg", args)
 		} else if args[0].Type() != TypeOf(K("")) {
-			t.Errorf("args[0] is type %v, want %v", args[0].Type, TypeOf(K("")))
+			t.Errorf("args[0] is type %v, want %v", args[0].Type(), TypeOf(K("")))
 		} else if args[0].String() != "gopher" {
 			t.Errorf("args[0] = %q, want %q", args[0].String(), "gopher")
 		}
@@ -4128,7 +4712,7 @@ func TestFuncOf(t *testing.T) {
 	if len(outs) != 1 {
 		t.Fatalf("v.Call returned %v, want exactly one result", outs)
 	} else if outs[0].Type() != TypeOf(V(0)) {
-		t.Fatalf("c.Call[0] is type %v, want %v", outs[0].Type, TypeOf(V(0)))
+		t.Fatalf("c.Call[0] is type %v, want %v", outs[0].Type(), TypeOf(V(0)))
 	}
 	f := outs[0].Float()
 	if f != 3.14 {
@@ -4479,7 +5063,7 @@ func TestFieldByIndexNil(t *testing.T) {
 // off the stack into the frame will store an *Inner there, and then if a garbage collection
 // happens to scan that argument frame before it is discarded, it will scan the *Inner
 // memory as if it were an *Outer. If the two have different memory layouts, the
-// collection will intepret the memory incorrectly.
+// collection will interpret the memory incorrectly.
 //
 // One such possible incorrect interpretation is to treat two arbitrary memory words
 // (Inner.P1 and Inner.P2 below) as an interface (Outer.R below). Because interpreting
@@ -4555,7 +5139,7 @@ func useStack(n int) {
 
 type Impl struct{}
 
-func (Impl) f() {}
+func (Impl) F() {}
 
 func TestValueString(t *testing.T) {
 	rv := ValueOf(Impl{})
@@ -4589,6 +5173,41 @@ func TestLargeGCProg(t *testing.T) {
 	fv.Call([]Value{ValueOf([256]*byte{})})
 }
 
+func fieldIndexRecover(t Type, i int) (recovered interface{}) {
+	defer func() {
+		recovered = recover()
+	}()
+
+	t.Field(i)
+	return
+}
+
+// Issue 15046.
+func TestTypeFieldOutOfRangePanic(t *testing.T) {
+	typ := TypeOf(struct{ X int }{10})
+	testIndices := [...]struct {
+		i         int
+		mustPanic bool
+	}{
+		0: {-2, true},
+		1: {0, false},
+		2: {1, true},
+		3: {1 << 10, true},
+	}
+	for i, tt := range testIndices {
+		recoveredErr := fieldIndexRecover(typ, tt.i)
+		if tt.mustPanic {
+			if recoveredErr == nil {
+				t.Errorf("#%d: fieldIndex %d expected to panic", i, tt.i)
+			}
+		} else {
+			if recoveredErr != nil {
+				t.Errorf("#%d: got err=%v, expected no panic", i, recoveredErr)
+			}
+		}
+	}
+}
+
 // Issue 9179.
 func TestCallGC(t *testing.T) {
 	f := func(a, b, c, d, e string) {
@@ -4716,7 +5335,7 @@ func init() {
 			2 * PtrSize,
 			[]byte{1},
 			[]byte{1},
-			// Note: this one is tricky, as the receiver is not a pointer.  But we
+			// Note: this one is tricky, as the receiver is not a pointer. But we
 			// pass the receiver by reference to the autogenerated pointer-receiver
 			// version of the function.
 		})
@@ -4768,6 +5387,9 @@ func verifyGCBitsSlice(t *testing.T, typ Type, cap int, bits []byte) {
 	for len(bits) > 2 && bits[len(bits)-1] == 0 {
 		bits = bits[:len(bits)-1]
 	}
+	if len(bits) == 2 && bits[0] == 0 && bits[1] == 0 {
+		bits = bits[:0]
+	}
 	if !bytes.Equal(heapBits, bits) {
 		t.Errorf("heapBits incorrect for make(%v, 0, %v)\nhave %v\nwant %v", typ, cap, heapBits, bits)
 	}
@@ -5027,6 +5649,140 @@ func TestChanAlloc(t *testing.T) {
 		t.Errorf("allocs per chan send/recv: want 1 got %f", allocs)
 	}
 	// Note: there is one allocation in reflect.recv which seems to be
-	// a limitation of escape analysis.  If that is ever fixed the
+	// a limitation of escape analysis. If that is ever fixed the
 	// allocs < 0.5 condition will trigger and this test should be fixed.
 }
+
+type TheNameOfThisTypeIsExactly255BytesLongSoWhenTheCompilerPrependsTheReflectTestPackageNameAndExtraStarTheLinkerRuntimeAndReflectPackagesWillHaveToCorrectlyDecodeTheSecondLengthByte0123456789_0123456789_0123456789_0123456789_0123456789_012345678 int
+
+type nameTest struct {
+	v    interface{}
+	want string
+}
+
+var nameTests = []nameTest{
+	{(*int32)(nil), "int32"},
+	{(*D1)(nil), "D1"},
+	{(*[]D1)(nil), ""},
+	{(*chan D1)(nil), ""},
+	{(*func() D1)(nil), ""},
+	{(*<-chan D1)(nil), ""},
+	{(*chan<- D1)(nil), ""},
+	{(*interface{})(nil), ""},
+	{(*interface {
+		F()
+	})(nil), ""},
+	{(*TheNameOfThisTypeIsExactly255BytesLongSoWhenTheCompilerPrependsTheReflectTestPackageNameAndExtraStarTheLinkerRuntimeAndReflectPackagesWillHaveToCorrectlyDecodeTheSecondLengthByte0123456789_0123456789_0123456789_0123456789_0123456789_012345678)(nil), "TheNameOfThisTypeIsExactly255BytesLongSoWhenTheCompilerPrependsTheReflectTestPackageNameAndExtraStarTheLinkerRuntimeAndReflectPackagesWillHaveToCorrectlyDecodeTheSecondLengthByte0123456789_0123456789_0123456789_0123456789_0123456789_012345678"},
+}
+
+func TestNames(t *testing.T) {
+	for _, test := range nameTests {
+		typ := TypeOf(test.v).Elem()
+		if got := typ.Name(); got != test.want {
+			t.Errorf("%v Name()=%q, want %q", typ, got, test.want)
+		}
+	}
+}
+
+/*
+gccgo doesn't really record whether a type is exported.
+It's not in the reflect API anyhow.
+
+func TestExported(t *testing.T) {
+	type ΦExported struct{}
+	type φUnexported struct{}
+	type BigP *big
+	type P int
+	type p *P
+	type P2 p
+	type p3 p
+
+	type exportTest struct {
+		v    interface{}
+		want bool
+	}
+	exportTests := []exportTest{
+		{D1{}, true},
+		{(*D1)(nil), true},
+		{big{}, false},
+		{(*big)(nil), false},
+		{(BigP)(nil), true},
+		{(*BigP)(nil), true},
+		{ΦExported{}, true},
+		{φUnexported{}, false},
+		{P(0), true},
+		{(p)(nil), false},
+		{(P2)(nil), true},
+		{(p3)(nil), false},
+	}
+
+	for i, test := range exportTests {
+		typ := TypeOf(test.v)
+		if got := IsExported(typ); got != test.want {
+			t.Errorf("%d: %s exported=%v, want %v", i, typ.Name(), got, test.want)
+		}
+	}
+}
+*/
+
+type embed struct {
+	EmbedWithUnexpMeth
+}
+
+/*
+func TestNameBytesAreAligned(t *testing.T) {
+	typ := TypeOf(embed{})
+	b := FirstMethodNameBytes(typ)
+	v := uintptr(unsafe.Pointer(b))
+	if v%unsafe.Alignof((*byte)(nil)) != 0 {
+		t.Errorf("reflect.name.bytes pointer is not aligned: %x", v)
+	}
+}
+*/
+
+func TestTypeStrings(t *testing.T) {
+	type stringTest struct {
+		typ  Type
+		want string
+	}
+	stringTests := []stringTest{
+		{TypeOf(func(int) {}), "func(int)"},
+		{FuncOf([]Type{TypeOf(int(0))}, nil, false), "func(int)"},
+		{TypeOf(XM{}), "reflect_test.XM"},
+		{TypeOf(new(XM)), "*reflect_test.XM"},
+		{TypeOf(new(XM).String), "func() string"},
+		{TypeOf(new(XM)).Method(0).Type, "func(*reflect_test.XM) string"},
+	}
+
+	for i, test := range stringTests {
+		if got, want := test.typ.String(), test.want; got != want {
+			t.Errorf("type %d String()=%q, want %q", i, got, want)
+		}
+	}
+}
+
+/*
+gccgo does not have resolveReflectName.
+
+func TestOffsetLock(t *testing.T) {
+	var wg sync.WaitGroup
+	for i := 0; i < 4; i++ {
+		i := i
+		wg.Add(1)
+		go func() {
+			for j := 0; j < 50; j++ {
+				ResolveReflectName(fmt.Sprintf("OffsetLockName:%d:%d", i, j))
+			}
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}
+*/
+
+func BenchmarkNew(b *testing.B) {
+	v := TypeOf(XM{})
+	for i := 0; i < b.N; i++ {
+		New(v)
+	}
+}
diff --git a/libgo/go/reflect/deepequal.go b/libgo/go/reflect/deepequal.go
index 3743e8042d3..9770358ae77 100644
--- a/libgo/go/reflect/deepequal.go
+++ b/libgo/go/reflect/deepequal.go
@@ -9,7 +9,7 @@ package reflect
 import "unsafe"
 
 // During deepValueEqual, must keep track of checks that are
-// in progress.  The comparison algorithm assumes that all
+// in progress. The comparison algorithm assumes that all
 // checks in progress are true when it reencounters them.
 // Visited comparisons are stored in a map indexed by visit.
 type visit struct {
diff --git a/libgo/go/reflect/example_test.go b/libgo/go/reflect/example_test.go
index 8ebf9765b8d..9e2b9b3e972 100644
--- a/libgo/go/reflect/example_test.go
+++ b/libgo/go/reflect/example_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -67,6 +67,34 @@ func ExampleStructTag() {
 	// blue gopher
 }
 
+func ExampleStructTag_Lookup() {
+	type S struct {
+		F0 string `alias:"field_0"`
+		F1 string `alias:""`
+		F2 string
+	}
+
+	s := S{}
+	st := reflect.TypeOf(s)
+	for i := 0; i < st.NumField(); i++ {
+		field := st.Field(i)
+		if alias, ok := field.Tag.Lookup("alias"); ok {
+			if alias == "" {
+				fmt.Println("(blank)")
+			} else {
+				fmt.Println(alias)
+			}
+		} else {
+			fmt.Println("(not specified)")
+		}
+	}
+
+	// Output:
+	// field_0
+	// (blank)
+	// (not specified)
+}
+
 func ExampleTypeOf() {
 	// As interface types are only used for static typing, a
 	// common idiom to find the reflection Type for an interface
diff --git a/libgo/go/reflect/export_test.go b/libgo/go/reflect/export_test.go
index bdbd60074ac..a06e8d0a944 100644
--- a/libgo/go/reflect/export_test.go
+++ b/libgo/go/reflect/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -41,3 +41,45 @@ func MapBucketOf(x, y Type) Type {
 func CachedBucketOf(m Type) Type {
 	return nil
 }
+
+type EmbedWithUnexpMeth struct{}
+
+func (EmbedWithUnexpMeth) f() {}
+
+type pinUnexpMeth interface {
+	f()
+}
+
+var pinUnexpMethI = pinUnexpMeth(EmbedWithUnexpMeth{})
+
+/*
+func FirstMethodNameBytes(t Type) *byte {
+	_ = pinUnexpMethI
+
+	ut := t.uncommon()
+	if ut == nil {
+		panic("type has no methods")
+	}
+	m := ut.methods()[0]
+	mname := t.(*rtype).nameOff(m.name)
+	if *mname.data(0)&(1<<2) == 0 {
+		panic("method name does not have pkgPath *string")
+	}
+	return mname.bytes
+}
+*/
+
+type OtherPkgFields struct {
+	OtherExported   int
+	otherUnexported int
+}
+
+func IsExported(t Type) bool {
+	return t.PkgPath() == ""
+}
+
+/*
+func ResolveReflectName(s string) {
+	resolveReflectName(newName(s, "", "", false))
+}
+*/
diff --git a/libgo/go/reflect/makefunc.go b/libgo/go/reflect/makefunc.go
index 7ec277b864a..543a335d841 100644
--- a/libgo/go/reflect/makefunc.go
+++ b/libgo/go/reflect/makefunc.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/reflect/set_test.go b/libgo/go/reflect/set_test.go
index 85dc55e6812..bc35c78e1bb 100644
--- a/libgo/go/reflect/set_test.go
+++ b/libgo/go/reflect/set_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -194,11 +194,13 @@ var assignableTests = []struct {
 	{new(*int), new(IntPtr), true},
 	{new(IntPtr), new(*int), true},
 	{new(IntPtr), new(IntPtr1), false},
+	{new(Ch), new(<-chan interface{}), true},
 	// test runs implementsTests too
 }
 
 type IntPtr *int
 type IntPtr1 *int
+type Ch <-chan interface{}
 
 func TestAssignableTo(t *testing.T) {
 	for _, tt := range append(assignableTests, implementsTests...) {
diff --git a/libgo/go/reflect/type.go b/libgo/go/reflect/type.go
index 88da632584c..d89f15631ac 100644
--- a/libgo/go/reflect/type.go
+++ b/libgo/go/reflect/type.go
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // Package reflect implements run-time reflection, allowing a program to
-// manipulate objects with arbitrary types.  The typical use is to take a value
+// manipulate objects with arbitrary types. The typical use is to take a value
 // with static type interface{} and extract its dynamic type information by
 // calling TypeOf, which returns a Type.
 //
@@ -24,10 +24,10 @@ import (
 
 // Type is the representation of a Go type.
 //
-// Not all methods apply to all kinds of types.  Restrictions,
+// Not all methods apply to all kinds of types. Restrictions,
 // if any, are noted in the documentation for each method.
 // Use the Kind method to find out the kind of type before
-// calling kind-specific methods.  Calling a method
+// calling kind-specific methods. Calling a method
 // inappropriate to the kind of type causes a run-time panic.
 type Type interface {
 	// Methods applicable to all types.
@@ -80,7 +80,7 @@ type Type interface {
 	// String returns a string representation of the type.
 	// The string representation may use shortened package names
 	// (e.g., base64 instead of "encoding/base64") and is not
-	// guaranteed to be unique among types.  To test for equality,
+	// guaranteed to be unique among types. To test for equality,
 	// compare the Types directly.
 	String() string
 
@@ -124,7 +124,7 @@ type Type interface {
 	ChanDir() ChanDir
 
 	// IsVariadic reports whether a function type's final input parameter
-	// is a "..." parameter.  If so, t.In(t.NumIn() - 1) returns the parameter's
+	// is a "..." parameter. If so, t.In(t.NumIn() - 1) returns the parameter's
 	// implicit actual type []T.
 	//
 	// For concreteness, if t represents func(x int, y ... float64), then
@@ -147,7 +147,7 @@ type Type interface {
 	Field(i int) StructField
 
 	// FieldByIndex returns the nested field corresponding
-	// to the index sequence.  It is equivalent to calling Field
+	// to the index sequence. It is equivalent to calling Field
 	// successively for each index i.
 	// It panics if the type's Kind is not Struct.
 	FieldByIndex(index []int) StructField
@@ -389,7 +389,7 @@ const (
 type Method struct {
 	// Name is the method name.
 	// PkgPath is the package path that qualifies a lower case (unexported)
-	// method name.  It is empty for upper case (exported) method names.
+	// method name. It is empty for upper case (exported) method names.
 	// The combination of PkgPath and Name uniquely identifies a method
 	// in a method set.
 	// See https://golang.org/ref/spec#Uniqueness_of_identifiers
@@ -509,6 +509,21 @@ func (t *uncommonType) Method(i int) (m Method) {
 	if t == nil || i < 0 || i >= len(t.methods) {
 		panic("reflect: Method index out of range")
 	}
+	found := false
+	for mi := range t.methods {
+		if t.methods[mi].pkgPath == nil {
+			if i == 0 {
+				i = mi
+				found = true
+				break
+			}
+			i--
+		}
+	}
+	if !found {
+		panic("reflect: Method index out of range")
+	}
+
 	p := &t.methods[i]
 	if p.name != nil {
 		m.Name = *p.name
@@ -531,7 +546,13 @@ func (t *uncommonType) NumMethod() int {
 	if t == nil {
 		return 0
 	}
-	return len(t.methods)
+	c := 0
+	for i := range t.methods {
+		if t.methods[i].pkgPath == nil {
+			c++
+		}
+	}
+	return c
 }
 
 func (t *uncommonType) MethodByName(name string) (m Method, ok bool) {
@@ -541,7 +562,7 @@ func (t *uncommonType) MethodByName(name string) (m Method, ok bool) {
 	var p *method
 	for i := range t.methods {
 		p = &t.methods[i]
-		if p.name != nil && *p.name == name {
+		if p.pkgPath == nil && p.name != nil && *p.name == name {
 			return t.Method(i), true
 		}
 	}
@@ -758,7 +779,7 @@ type StructField struct {
 	// Name is the field name.
 	Name string
 	// PkgPath is the package path that qualifies a lower case (unexported)
-	// field name.  It is empty for upper case (exported) field names.
+	// field name. It is empty for upper case (exported) field names.
 	// See https://golang.org/ref/spec#Uniqueness_of_identifiers
 	PkgPath string
 
@@ -782,8 +803,20 @@ type StructTag string
 // Get returns the value associated with key in the tag string.
 // If there is no such key in the tag, Get returns the empty string.
 // If the tag does not have the conventional format, the value
-// returned by Get is unspecified.
+// returned by Get is unspecified. To determine whether a tag is
+// explicitly set to the empty string, use Lookup.
 func (tag StructTag) Get(key string) string {
+	v, _ := tag.Lookup(key)
+	return v
+}
+
+// Lookup returns the value associated with key in the tag string.
+// If the key is present in the tag the value (which may be empty)
+// is returned. Otherwise the returned value will be the empty string.
+// The ok return value reports whether the value was explicitly set in
+// the tag string. If the tag does not have the conventional format,
+// the value returned by Lookup is unspecified.
+func (tag StructTag) Lookup(key string) (value string, ok bool) {
 	// When modifying this code, also update the validateStructTag code
 	// in golang.org/x/tools/cmd/vet/structtag.go.
 
@@ -831,16 +864,16 @@ func (tag StructTag) Get(key string) string {
 			if err != nil {
 				break
 			}
-			return value
+			return value, true
 		}
 	}
-	return ""
+	return "", false
 }
 
 // Field returns the i'th struct field.
 func (t *structType) Field(i int) (f StructField) {
 	if i < 0 || i >= len(t.fields) {
-		return
+		panic("reflect: Field index out of bounds")
 	}
 	p := &t.fields[i]
 	f.Type = toType(p.typ)
@@ -863,12 +896,12 @@ func (t *structType) Field(i int) (f StructField) {
 	f.Offset = p.offset
 
 	// NOTE(rsc): This is the only allocation in the interface
-	// presented by a reflect.Type.  It would be nice to avoid,
+	// presented by a reflect.Type. It would be nice to avoid,
 	// at least in the common cases, but we need to make sure
 	// that misbehaving clients of reflect cannot affect other
-	// uses of reflect.  One possibility is CL 5371098, but we
+	// uses of reflect. One possibility is CL 5371098, but we
 	// postponed that ugliness until there is a demonstrated
-	// need for the performance.  This is issue 2320.
+	// need for the performance. This is issue 2320.
 	f.Index = []int{i}
 	return
 }
@@ -1082,11 +1115,7 @@ func (t *rtype) ptrTo() *rtype {
 		return p
 	}
 
-	// Otherwise, synthesize one.
-	// This only happens for pointers with no methods.
-	// We keep the mapping in a map on the side, because
-	// this operation is rare and a separate map lets us keep
-	// the type structures in read-only memory.
+	// Check the cache.
 	ptrMap.RLock()
 	if m := ptrMap.m; m != nil {
 		if p := m[t]; p != nil {
@@ -1095,6 +1124,7 @@ func (t *rtype) ptrTo() *rtype {
 		}
 	}
 	ptrMap.RUnlock()
+
 	ptrMap.Lock()
 	if ptrMap.m == nil {
 		ptrMap.m = make(map[*rtype]*ptrType)
@@ -1762,7 +1792,7 @@ func needKeyUpdate(t *rtype) bool {
 
 // Make sure these routines stay in sync with ../../runtime/hashmap.go!
 // These types exist only for GC, so we only fill out GC relevant info.
-// Currently, that's just size and the GC program.  We also fill in string
+// Currently, that's just size and the GC program. We also fill in string
 // for possible debugging use.
 const (
 	bucketSize uintptr = 8
@@ -1866,7 +1896,7 @@ func bucketOf(ktyp, etyp *rtype) *rtype {
 }
 
 // Take the GC program for "t" and append it to the GC program "gc".
-func appendGCProgram(gc []uintptr, t *rtype) []uintptr {
+func appendGCProgram(gc []uintptr, t *rtype, offset uintptr) []uintptr {
 	p := t.gc
 	p = unsafe.Pointer(uintptr(p) + unsafe.Sizeof(uintptr(0))) // skip size
 loop:
@@ -1888,7 +1918,11 @@ loop:
 			panic("unknown GC program op for " + *t.string + ": " + strconv.FormatUint(*(*uint64)(p), 10))
 		}
 		for i := 0; i < argcnt+1; i++ {
-			gc = append(gc, *(*uintptr)(p))
+			v := *(*uintptr)(p)
+			if i == 1 {
+				v += offset
+			}
+			gc = append(gc, v)
 			p = unsafe.Pointer(uintptr(p) + unsafe.Sizeof(uintptr(0)))
 		}
 	}
@@ -1997,8 +2031,247 @@ func SliceOf(t Type) Type {
 	return cachePut(ckey, &slice.rtype)
 }
 
-// See cmd/compile/internal/gc/reflect.go for derivation of constant.
-const maxPtrmaskBytes = 2048
+// The structLookupCache caches StructOf lookups.
+// StructOf does not share the common lookupCache since we need to pin
+// the memory associated with *structTypeFixedN.
+var structLookupCache struct {
+	sync.RWMutex
+	m map[uint32][]interface {
+		common() *rtype
+	} // keyed by hash calculated in StructOf
+}
+
+// StructOf returns the struct type containing fields.
+// The Offset and Index fields are ignored and computed as they would be
+// by the compiler.
+//
+// StructOf currently does not generate wrapper methods for embedded fields.
+// This limitation may be lifted in a future version.
+func StructOf(fields []StructField) Type {
+	var (
+		hash     = uint32(0)
+		size     uintptr
+		typalign int8
+
+		fs   = make([]structField, len(fields))
+		repr = make([]byte, 0, 64)
+		fset = map[string]struct{}{} // fields' names
+
+		hasPtr = false // records whether at least one struct-field is a pointer
+	)
+
+	repr = append(repr, "struct {"...)
+	for i, field := range fields {
+		if field.Type == nil {
+			panic("reflect.StructOf: field " + strconv.Itoa(i) + " has no type")
+		}
+		f := runtimeStructField(field)
+		ft := f.typ
+		if ft.pointers() {
+			hasPtr = true
+		}
+
+		name := ""
+		// Update string and hash
+		hash = (hash << 1) + ft.hash
+		if f.name != nil {
+			name = *f.name
+			repr = append(repr, (" " + name)...)
+		} else {
+			// Embedded field
+			repr = append(repr, " ?"...)
+			if f.typ.Kind() == Ptr {
+				// Embedded ** and *interface{} are illegal
+				elem := ft.Elem()
+				if k := elem.Kind(); k == Ptr || k == Interface {
+					panic("reflect.StructOf: illegal anonymous field type " + ft.String())
+				}
+				name = elem.String()
+			} else {
+				name = ft.String()
+			}
+			// TODO(sbinet) check for syntactically impossible type names?
+
+			switch f.typ.Kind() {
+			case Interface:
+				ift := (*interfaceType)(unsafe.Pointer(ft))
+				if len(ift.methods) > 0 {
+					panic("reflect.StructOf: embedded field with methods not supported")
+				}
+			case Ptr:
+				ptr := (*ptrType)(unsafe.Pointer(ft))
+				if unt := ptr.uncommon(); unt != nil {
+					if len(unt.methods) > 0 {
+						panic("reflect.StructOf: embedded field with methods not supported")
+					}
+				}
+				if unt := ptr.elem.uncommon(); unt != nil {
+					if len(unt.methods) > 0 {
+						panic("reflect.StructOf: embedded field with methods not supported")
+					}
+				}
+			default:
+				if unt := ft.uncommon(); unt != nil {
+					if len(unt.methods) > 0 {
+						panic("reflect.StructOf: embedded field with methods not supported")
+					}
+				}
+			}
+		}
+		if _, dup := fset[name]; dup {
+			panic("reflect.StructOf: duplicate field " + name)
+		}
+		fset[name] = struct{}{}
+
+		repr = append(repr, (" " + ft.String())...)
+		if f.tag != nil {
+			repr = append(repr, (" " + strconv.Quote(*f.tag))...)
+		}
+		if i < len(fields)-1 {
+			repr = append(repr, ';')
+		}
+
+		f.offset = align(size, uintptr(ft.fieldAlign))
+		if int8(ft.fieldAlign) > typalign {
+			typalign = int8(ft.fieldAlign)
+		}
+		size = f.offset + ft.size
+
+		fs[i] = f
+	}
+
+	if len(fs) > 0 {
+		repr = append(repr, ' ')
+	}
+	repr = append(repr, '}')
+	hash <<= 2
+	str := string(repr)
+
+	// Round the size up to be a multiple of the alignment.
+	size = align(size, uintptr(typalign))
+
+	// Make the struct type.
+	var istruct interface{} = struct{}{}
+	prototype := *(**structType)(unsafe.Pointer(&istruct))
+	typ := new(structType)
+	*typ = *prototype
+	typ.fields = fs
+
+	// Look in cache
+	structLookupCache.RLock()
+	for _, st := range structLookupCache.m[hash] {
+		t := st.common()
+		if haveIdenticalUnderlyingType(&typ.rtype, t) {
+			structLookupCache.RUnlock()
+			return t
+		}
+	}
+	structLookupCache.RUnlock()
+
+	// not in cache, lock and retry
+	structLookupCache.Lock()
+	defer structLookupCache.Unlock()
+	if structLookupCache.m == nil {
+		structLookupCache.m = make(map[uint32][]interface {
+			common() *rtype
+		})
+	}
+	for _, st := range structLookupCache.m[hash] {
+		t := st.common()
+		if haveIdenticalUnderlyingType(&typ.rtype, t) {
+			return t
+		}
+	}
+
+	typ.string = &str
+	typ.hash = hash
+	typ.size = size
+	typ.align = typalign
+	typ.fieldAlign = uint8(typalign)
+	if !hasPtr {
+		typ.kind |= kindNoPointers
+		gc := [...]uintptr{size, _GC_END}
+		typ.gc = unsafe.Pointer(&gc[0])
+	} else {
+		typ.kind &^= kindNoPointers
+		gc := []uintptr{size}
+		for _, ft := range fs {
+			gc = appendGCProgram(gc, ft.typ, ft.offset)
+		}
+		gc = append(gc, _GC_END)
+		typ.gc = unsafe.Pointer(&gc[0])
+	}
+
+	typ.hashfn = func(p unsafe.Pointer, size uintptr) uintptr {
+		ret := uintptr(0)
+		for i, ft := range typ.fields {
+			if i > 0 {
+				ret *= 33
+			}
+			o := unsafe.Pointer(uintptr(p) + ft.offset)
+			ret += ft.typ.hashfn(o, ft.typ.size)
+		}
+		return ret
+	}
+
+	typ.equalfn = func(p, q unsafe.Pointer, size uintptr) bool {
+		for _, ft := range typ.fields {
+			pi := unsafe.Pointer(uintptr(p) + ft.offset)
+			qi := unsafe.Pointer(uintptr(q) + ft.offset)
+			if !ft.typ.equalfn(pi, qi, ft.typ.size) {
+				return false
+			}
+		}
+		return true
+	}
+
+	typ.kind &^= kindDirectIface
+	typ.uncommonType = nil
+	typ.ptrToThis = nil
+
+	structLookupCache.m[hash] = append(structLookupCache.m[hash], typ)
+	return &typ.rtype
+}
+
+func runtimeStructField(field StructField) structField {
+	var name *string
+	if field.Name == "" {
+		t := field.Type.(*rtype)
+		if t.Kind() == Ptr {
+			t = t.Elem().(*rtype)
+		}
+	} else if field.PkgPath == "" {
+		s := field.Name
+		name = &s
+		b0 := s[0]
+		if ('a' <= b0 && b0 <= 'z') || b0 == '_' {
+			panic("reflect.StructOf: field \"" + field.Name + "\" is unexported but has no PkgPath")
+		}
+	}
+
+	var pkgPath *string
+	if field.PkgPath != "" {
+		s := field.PkgPath
+		pkgPath = &s
+		// This could work with gccgo but we panic to be
+		// compatible with gc.
+		panic("reflect: creating a name with a package path is not supported")
+	}
+
+	var tag *string
+	if field.Tag != "" {
+		s := string(field.Tag)
+		tag = &s
+	}
+
+	return structField{
+		name:    name,
+		pkgPath: pkgPath,
+		typ:     field.Type.common(),
+		tag:     tag,
+		offset:  0,
+	}
+}
 
 // ArrayOf returns the array type with the given count and element type.
 // For example, if t represents int, ArrayOf(5, t) represents [5]int.
@@ -2037,6 +2310,7 @@ func ArrayOf(count int, elem Type) Type {
 	array.hash = typ.hash + 1 + 13
 
 	array.elem = typ
+	array.ptrToThis = nil
 	max := ^uintptr(0) / typ.size
 	if uintptr(count) > max {
 		panic("reflect.ArrayOf: array size would exceed virtual address space")
@@ -2048,7 +2322,6 @@ func ArrayOf(count int, elem Type) Type {
 	array.align = typ.align
 	array.fieldAlign = typ.fieldAlign
 	array.uncommonType = nil
-	array.ptrToThis = nil
 	array.len = uintptr(count)
 	array.slice = slice.(*rtype)
 
@@ -2067,7 +2340,7 @@ func ArrayOf(count int, elem Type) Type {
 
 	default:
 		gc := []uintptr{array.size, _GC_ARRAY_START, 0, uintptr(count), typ.size}
-		gc = appendGCProgram(gc, typ)
+		gc = appendGCProgram(gc, typ, 0)
 		gc = append(gc, _GC_ARRAY_NEXT, _GC_END)
 		array.gc = unsafe.Pointer(&gc[0])
 	}
diff --git a/libgo/go/reflect/value.go b/libgo/go/reflect/value.go
index 75944a6e532..1d1887693d3 100644
--- a/libgo/go/reflect/value.go
+++ b/libgo/go/reflect/value.go
@@ -11,14 +11,13 @@ import (
 )
 
 const ptrSize = 4 << (^uintptr(0) >> 63) // unsafe.Sizeof(uintptr(0)) but an ideal const
-const cannotSet = "cannot set value obtained from unexported struct field"
 
 // Value is the reflection interface to a Go value.
 //
-// Not all methods apply to all kinds of values.  Restrictions,
+// Not all methods apply to all kinds of values. Restrictions,
 // if any, are noted in the documentation for each method.
 // Use the Kind method to find out the kind of value before
-// calling kind-specific methods.  Calling a method
+// calling kind-specific methods. Calling a method
 // inappropriate to the kind of type causes a run time panic.
 //
 // The zero Value represents no value.
@@ -57,7 +56,7 @@ type Value struct {
 	flag
 
 	// A method value represents a curried method invocation
-	// like r.Read for some receiver r.  The typ+val+flag bits describe
+	// like r.Read for some receiver r. The typ+val+flag bits describe
 	// the receiver r, but the flag's Kind bits say Func (methods are
 	// functions), and the top bits of the flag give the method number
 	// in r's type's method table.
@@ -116,14 +115,14 @@ func packEface(v Value) interface{} {
 		}
 		e.word = ptr
 	case v.flag&flagIndir != 0:
-		// Value is indirect, but interface is direct.  We need
+		// Value is indirect, but interface is direct. We need
 		// to load the data at v.ptr into the interface data word.
 		e.word = *(*unsafe.Pointer)(v.ptr)
 	default:
 		// Value is direct, and so is the interface.
 		e.word = v.ptr
 	}
-	// Now, fill in the type portion.  We're very careful here not
+	// Now, fill in the type portion. We're very careful here not
 	// to have any operation between the e.word and e.typ assignments
 	// that would let the garbage collector observe the partially-built
 	// interface value.
@@ -147,7 +146,7 @@ func unpackEface(i interface{}) Value {
 }
 
 // A ValueError occurs when a Value method is invoked on
-// a Value that does not support it.  Such cases are documented
+// a Value that does not support it. Such cases are documented
 // in the description of each method.
 type ValueError struct {
 	Method string
@@ -269,7 +268,7 @@ func (v Value) runes() []rune {
 }
 
 // CanAddr reports whether the value's address can be obtained with Addr.
-// Such values are called addressable.  A value is addressable if it is
+// Such values are called addressable. A value is addressable if it is
 // an element of a slice, an element of an addressable array,
 // a field of an addressable struct, or the result of dereferencing a pointer.
 // If CanAddr returns false, calling Addr will panic.
@@ -500,7 +499,7 @@ func methodReceiver(op string, v Value, methodIndex int) (rcvrtype, t *rtype, fn
 	return
 }
 
-// v is a method receiver.  Store at p the word which is used to
+// v is a method receiver. Store at p the word which is used to
 // encode that receiver at the start of the argument list.
 // Reflect uses the "interface" calling convention for
 // methods, which always uses one word to record the receiver.
@@ -541,7 +540,7 @@ func (v Value) Cap() int {
 	case Array:
 		return v.typ.Len()
 	case Chan:
-		return int(chancap(v.pointer()))
+		return chancap(v.pointer())
 	case Slice:
 		// Slice is always bigger than a word; assume flagIndir.
 		return (*sliceHeader)(v.ptr).Cap
@@ -760,7 +759,7 @@ func (v Value) Int() int64 {
 	case Int32:
 		return int64(*(*int32)(p))
 	case Int64:
-		return int64(*(*int64)(p))
+		return *(*int64)(p)
 	}
 	panic(&ValueError{"reflect.Value.Int", v.kind()})
 }
@@ -909,9 +908,9 @@ func (v Value) MapIndex(key Value) Value {
 
 	// Do not require key to be exported, so that DeepEqual
 	// and other programs can use all the keys returned by
-	// MapKeys as arguments to MapIndex.  If either the map
+	// MapKeys as arguments to MapIndex. If either the map
 	// or the key is unexported, though, the result will be
-	// considered unexported.  This is consistent with the
+	// considered unexported. This is consistent with the
 	// behavior for structs, which allow read but not write
 	// of unexported fields.
 	key = key.assignTo("reflect.Value.MapIndex", tt.key, nil)
@@ -963,7 +962,7 @@ func (v Value) MapKeys() []Value {
 		key := mapiterkey(it)
 		if key == nil {
 			// Someone deleted an entry from the map since we
-			// called maplen above.  It's a data race, but nothing
+			// called maplen above. It's a data race, but nothing
 			// we can do about it.
 			break
 		}
@@ -1110,7 +1109,7 @@ func (v Value) OverflowUint(x uint64) bool {
 // result is zero if and only if v is a nil func Value.
 //
 // If v's Kind is Slice, the returned pointer is to the first
-// element of the slice.  If the slice is nil the returned value
+// element of the slice. If the slice is nil the returned value
 // is 0.  If the slice is empty but non-nil the return value is non-zero.
 func (v Value) Pointer() uintptr {
 	// TODO: deprecate
@@ -1311,7 +1310,7 @@ func (v Value) SetCap(n int) {
 	v.mustBeAssignable()
 	v.mustBe(Slice)
 	s := (*sliceHeader)(v.ptr)
-	if n < int(s.Len) || n > int(s.Cap) {
+	if n < s.Len || n > s.Cap {
 		panic("reflect: slice capacity out of range in SetCap")
 	}
 	s.Cap = n
@@ -1413,7 +1412,7 @@ func (v Value) Slice(i, j int) Value {
 	case Slice:
 		typ = (*sliceType)(unsafe.Pointer(v.typ))
 		s := (*sliceHeader)(v.ptr)
-		base = unsafe.Pointer(s.Data)
+		base = s.Data
 		cap = s.Cap
 
 	case String:
@@ -1585,7 +1584,7 @@ func (v Value) Uint() uint64 {
 	case Uint32:
 		return uint64(*(*uint32)(p))
 	case Uint64:
-		return uint64(*(*uint64)(p))
+		return *(*uint64)(p)
 	case Uintptr:
 		return uint64(*(*uintptr)(p))
 	}
@@ -1751,13 +1750,13 @@ func Copy(dst, src Value) int {
 // A runtimeSelect is a single case passed to rselect.
 // This must match ../runtime/select.go:/runtimeSelect
 type runtimeSelect struct {
-	dir uintptr        // 0, SendDir, or RecvDir
+	dir SelectDir      // SelectSend, SelectRecv or SelectDefault
 	typ *rtype         // channel type
 	ch  unsafe.Pointer // channel
 	val unsafe.Pointer // ptr to data (SendDir) or ptr to receive buffer (RecvDir)
 }
 
-// rselect runs a select.  It returns the index of the chosen case.
+// rselect runs a select. It returns the index of the chosen case.
 // If the case was a receive, val is filled in with the received value.
 // The conventional OK bool indicates whether the receive corresponds
 // to a sent value.
@@ -1814,7 +1813,7 @@ func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
 	haveDefault := false
 	for i, c := range cases {
 		rc := &runcases[i]
-		rc.dir = uintptr(c.Dir)
+		rc.dir = c.Dir
 		switch c.Dir {
 		default:
 			panic("reflect.Select: invalid Dir")
@@ -1877,7 +1876,7 @@ func Select(cases []SelectCase) (chosen int, recv Value, recvOK bool) {
 	}
 
 	chosen, recvOK = rselect(runcases)
-	if runcases[chosen].dir == uintptr(SelectRecv) {
+	if runcases[chosen].dir == SelectRecv {
 		tt := (*chanType)(unsafe.Pointer(runcases[chosen].typ))
 		t := tt.elem
 		p := runcases[chosen].val
@@ -1954,14 +1953,14 @@ func Indirect(v Value) Value {
 }
 
 // ValueOf returns a new Value initialized to the concrete value
-// stored in the interface i.  ValueOf(nil) returns the zero Value.
+// stored in the interface i. ValueOf(nil) returns the zero Value.
 func ValueOf(i interface{}) Value {
 	if i == nil {
 		return Value{}
 	}
 
 	// TODO: Maybe allow contents of a Value to live on the stack.
-	// For now we make the contents always escape to the heap.  It
+	// For now we make the contents always escape to the heap. It
 	// makes life easier in a few places (see chanrecv/mapassign
 	// comment below).
 	escapes(i)
@@ -1987,7 +1986,7 @@ func Zero(typ Type) Value {
 }
 
 // New returns a Value representing a pointer to a new zero value
-// for the specified type.  That is, the returned Value's Type is PtrTo(typ).
+// for the specified type. That is, the returned Value's Type is PtrTo(typ).
 func New(typ Type) Value {
 	if typ == nil {
 		panic("reflect: New(nil)")
@@ -2142,13 +2141,13 @@ func makeInt(f flag, bits uint64, t Type) Value {
 	ptr := unsafe_New(typ)
 	switch typ.size {
 	case 1:
-		*(*uint8)(unsafe.Pointer(ptr)) = uint8(bits)
+		*(*uint8)(ptr) = uint8(bits)
 	case 2:
-		*(*uint16)(unsafe.Pointer(ptr)) = uint16(bits)
+		*(*uint16)(ptr) = uint16(bits)
 	case 4:
-		*(*uint32)(unsafe.Pointer(ptr)) = uint32(bits)
+		*(*uint32)(ptr) = uint32(bits)
 	case 8:
-		*(*uint64)(unsafe.Pointer(ptr)) = bits
+		*(*uint64)(ptr) = bits
 	}
 	return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
 }
@@ -2160,9 +2159,9 @@ func makeFloat(f flag, v float64, t Type) Value {
 	ptr := unsafe_New(typ)
 	switch typ.size {
 	case 4:
-		*(*float32)(unsafe.Pointer(ptr)) = float32(v)
+		*(*float32)(ptr) = float32(v)
 	case 8:
-		*(*float64)(unsafe.Pointer(ptr)) = v
+		*(*float64)(ptr) = v
 	}
 	return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
 }
@@ -2174,9 +2173,9 @@ func makeComplex(f flag, v complex128, t Type) Value {
 	ptr := unsafe_New(typ)
 	switch typ.size {
 	case 8:
-		*(*complex64)(unsafe.Pointer(ptr)) = complex64(v)
+		*(*complex64)(ptr) = complex64(v)
 	case 16:
-		*(*complex128)(unsafe.Pointer(ptr)) = v
+		*(*complex128)(ptr) = v
 	}
 	return Value{typ, ptr, f | flagIndir | flag(typ.Kind())}
 }
@@ -2320,7 +2319,7 @@ func chanclose(ch unsafe.Pointer)
 func chanlen(ch unsafe.Pointer) int
 
 // Note: some of the noescape annotations below are technically a lie,
-// but safe in the context of this package.  Functions like chansend
+// but safe in the context of this package. Functions like chansend
 // and mapassign don't escape the referent, but may escape anything
 // the referent points to (they do shallow copies of the referent).
 // It is safe in this package because the referent may only point
diff --git a/libgo/go/regexp/backtrack.go b/libgo/go/regexp/backtrack.go
index fd95604fe44..29f624b54c7 100644
--- a/libgo/go/regexp/backtrack.go
+++ b/libgo/go/regexp/backtrack.go
@@ -36,7 +36,6 @@ type bitState struct {
 
 	end     int
 	cap     []int
-	input   input
 	jobs    []job
 	visited []uint32
 }
@@ -146,7 +145,7 @@ func (m *machine) tryBacktrack(b *bitState, i input, pc uint32, pos int) bool {
 		// Optimization: rather than push and pop,
 		// code that is going to Push and continue
 		// the loop simply updates ip, p, and arg
-		// and jumps to CheckAndLoop.  We have to
+		// and jumps to CheckAndLoop. We have to
 		// do the ShouldVisit check that Push
 		// would have, but we avoid the stack
 		// manipulation.
@@ -254,7 +253,6 @@ func (m *machine) tryBacktrack(b *bitState, i input, pc uint32, pos int) bool {
 
 			}
 			panic("bad arg in InstCapture")
-			continue
 
 		case syntax.InstEmptyWidth:
 			if syntax.EmptyOp(inst.Arg)&^i.context(pos) != 0 {
@@ -299,7 +297,6 @@ func (m *machine) tryBacktrack(b *bitState, i input, pc uint32, pos int) bool {
 			// Otherwise, continue on in hope of a longer match.
 			continue
 		}
-		panic("unreachable")
 	}
 
 	return m.matched
diff --git a/libgo/go/regexp/exec.go b/libgo/go/regexp/exec.go
index 518272092ae..4fd61b5d8d1 100644
--- a/libgo/go/regexp/exec.go
+++ b/libgo/go/regexp/exec.go
@@ -19,7 +19,7 @@ type queue struct {
 // A entry is an entry on a queue.
 // It holds both the instruction pc and the actual thread.
 // Some queue entries are just place holders so that the machine
-// knows it has considered that pc.  Such entries have t == nil.
+// knows it has considered that pc. Such entries have t == nil.
 type entry struct {
 	pc uint32
 	t  *thread
@@ -107,14 +107,6 @@ func (m *machine) alloc(i *syntax.Inst) *thread {
 	return t
 }
 
-// free returns t to the free pool.
-func (m *machine) free(t *thread) {
-	m.inputBytes.str = nil
-	m.inputString.str = ""
-	m.inputReader.r = nil
-	m.pool = append(m.pool, t)
-}
-
 // match runs the machine over the input starting at pos.
 // It reports whether a match was found.
 // If so, m.matchcap holds the submatch information.
@@ -192,7 +184,6 @@ func (m *machine) match(i input, pos int) bool {
 func (m *machine) clear(q *queue) {
 	for _, d := range q.dense {
 		if d.t != nil {
-			// m.free(d.t)
 			m.pool = append(m.pool, d.t)
 		}
 	}
@@ -213,7 +204,6 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos int, c rune, nextCond sy
 			continue
 		}
 		if longest && m.matched && len(t.cap) > 0 && m.matchcap[0] < t.cap[0] {
-			// m.free(t)
 			m.pool = append(m.pool, t)
 			continue
 		}
@@ -232,7 +222,6 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos int, c rune, nextCond sy
 				// First-match mode: cut off all lower-priority threads.
 				for _, d := range runq.dense[j+1:] {
 					if d.t != nil {
-						// m.free(d.t)
 						m.pool = append(m.pool, d.t)
 					}
 				}
@@ -253,7 +242,6 @@ func (m *machine) step(runq, nextq *queue, pos, nextPos int, c rune, nextCond sy
 			t = m.add(nextq, i.Out, nextPos, t.cap, nextCond, t)
 		}
 		if t != nil {
-			// m.free(t)
 			m.pool = append(m.pool, t)
 		}
 	}
diff --git a/libgo/go/regexp/exec_test.go b/libgo/go/regexp/exec_test.go
index 4872cb3def4..69f187e38a8 100644
--- a/libgo/go/regexp/exec_test.go
+++ b/libgo/go/regexp/exec_test.go
@@ -22,7 +22,7 @@ import (
 // considered during RE2's exhaustive tests, which run all possible
 // regexps over a given set of atoms and operators, up to a given
 // complexity, over all possible strings over a given alphabet,
-// up to a given size.  Rather than try to link with RE2, we read a
+// up to a given size. Rather than try to link with RE2, we read a
 // log file containing the test cases and the expected matches.
 // The log file, re2-exhaustive.txt, is generated by running 'make log'
 // in the open source RE2 distribution https://github.com/google/re2/.
@@ -41,21 +41,21 @@ import (
 //	-;0-3 0-1 1-2 2-3
 //
 // The stanza begins by defining a set of strings, quoted
-// using Go double-quote syntax, one per line.  Then the
+// using Go double-quote syntax, one per line. Then the
 // regexps section gives a sequence of regexps to run on
-// the strings.  In the block that follows a regexp, each line
+// the strings. In the block that follows a regexp, each line
 // gives the semicolon-separated match results of running
 // the regexp on the corresponding string.
 // Each match result is either a single -, meaning no match, or a
 // space-separated sequence of pairs giving the match and
-// submatch indices.  An unmatched subexpression formats
+// submatch indices. An unmatched subexpression formats
 // its pair as a single - (not illustrated above).  For now
 // each regexp run produces two match results, one for a
 // ``full match'' that restricts the regexp to matching the entire
 // string or nothing, and one for a ``partial match'' that gives
 // the leftmost first match found in the string.
 //
-// Lines beginning with # are comments.  Lines beginning with
+// Lines beginning with # are comments. Lines beginning with
 // a capital letter are test names printed during RE2's test suite
 // and are echoed into t but otherwise ignored.
 //
@@ -155,9 +155,9 @@ func testRE2(t *testing.T, file string) {
 			if !isSingleBytes(text) && strings.Contains(re.String(), `\B`) {
 				// RE2's \B considers every byte position,
 				// so it sees 'not word boundary' in the
-				// middle of UTF-8 sequences.  This package
+				// middle of UTF-8 sequences. This package
 				// only considers the positions between runes,
-				// so it disagrees.  Skip those cases.
+				// so it disagrees. Skip those cases.
 				continue
 			}
 			res := strings.Split(line, ";")
@@ -409,7 +409,7 @@ Reading:
 		//     h	REG_MULTIREF		multiple digit backref
 		//     i	REG_ICASE		ignore case
 		//     j	REG_SPAN		. matches \n
-		//     k	REG_ESCAPE		\ to ecape [...] delimiter
+		//     k	REG_ESCAPE		\ to escape [...] delimiter
 		//     l	REG_LEFT		implicit ^...
 		//     m	REG_MINIMAL		minimal match
 		//     n	REG_NEWLINE		explicit \n match
@@ -658,47 +658,42 @@ func makeText(n int) []byte {
 	return text
 }
 
-func benchmark(b *testing.B, re string, n int) {
-	r := MustCompile(re)
-	t := makeText(n)
-	b.ResetTimer()
-	b.SetBytes(int64(n))
-	for i := 0; i < b.N; i++ {
-		if r.Match(t) {
-			b.Fatal("match!")
+func BenchmarkMatch(b *testing.B) {
+	for _, data := range benchData {
+		r := MustCompile(data.re)
+		for _, size := range benchSizes {
+			t := makeText(size.n)
+			b.Run(data.name+"/"+size.name, func(b *testing.B) {
+				b.SetBytes(int64(size.n))
+				for i := 0; i < b.N; i++ {
+					if r.Match(t) {
+						b.Fatal("match!")
+					}
+				}
+			})
 		}
 	}
 }
 
-const (
-	easy0  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
-	easy1  = "A[AB]B[BC]C[CD]D[DE]E[EF]F[FG]G[GH]H[HI]I[IJ]J$"
-	medium = "[XYZ]ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
-	hard   = "[ -~]*ABCDEFGHIJKLMNOPQRSTUVWXYZ$"
-	parens = "([ -~])*(A)(B)(C)(D)(E)(F)(G)(H)(I)(J)(K)(L)(M)" +
-		"(N)(O)(P)(Q)(R)(S)(T)(U)(V)(W)(X)(Y)(Z)$"
-)
+var benchData = []struct{ name, re string }{
+	{"Easy0", "ABCDEFGHIJKLMNOPQRSTUVWXYZ$"},
+	{"Easy0i", "(?i)ABCDEFGHIJklmnopqrstuvwxyz$"},
+	{"Easy1", "A[AB]B[BC]C[CD]D[DE]E[EF]F[FG]G[GH]H[HI]I[IJ]J$"},
+	{"Medium", "[XYZ]ABCDEFGHIJKLMNOPQRSTUVWXYZ$"},
+	{"Hard", "[ -~]*ABCDEFGHIJKLMNOPQRSTUVWXYZ$"},
+	{"Hard1", "ABCD|CDEF|EFGH|GHIJ|IJKL|KLMN|MNOP|OPQR|QRST|STUV|UVWX|WXYZ"},
+}
 
-func BenchmarkMatchEasy0_32(b *testing.B)   { benchmark(b, easy0, 32<<0) }
-func BenchmarkMatchEasy0_1K(b *testing.B)   { benchmark(b, easy0, 1<<10) }
-func BenchmarkMatchEasy0_32K(b *testing.B)  { benchmark(b, easy0, 32<<10) }
-func BenchmarkMatchEasy0_1M(b *testing.B)   { benchmark(b, easy0, 1<<20) }
-func BenchmarkMatchEasy0_32M(b *testing.B)  { benchmark(b, easy0, 32<<20) }
-func BenchmarkMatchEasy1_32(b *testing.B)   { benchmark(b, easy1, 32<<0) }
-func BenchmarkMatchEasy1_1K(b *testing.B)   { benchmark(b, easy1, 1<<10) }
-func BenchmarkMatchEasy1_32K(b *testing.B)  { benchmark(b, easy1, 32<<10) }
-func BenchmarkMatchEasy1_1M(b *testing.B)   { benchmark(b, easy1, 1<<20) }
-func BenchmarkMatchEasy1_32M(b *testing.B)  { benchmark(b, easy1, 32<<20) }
-func BenchmarkMatchMedium_32(b *testing.B)  { benchmark(b, medium, 32<<0) }
-func BenchmarkMatchMedium_1K(b *testing.B)  { benchmark(b, medium, 1<<10) }
-func BenchmarkMatchMedium_32K(b *testing.B) { benchmark(b, medium, 32<<10) }
-func BenchmarkMatchMedium_1M(b *testing.B)  { benchmark(b, medium, 1<<20) }
-func BenchmarkMatchMedium_32M(b *testing.B) { benchmark(b, medium, 32<<20) }
-func BenchmarkMatchHard_32(b *testing.B)    { benchmark(b, hard, 32<<0) }
-func BenchmarkMatchHard_1K(b *testing.B)    { benchmark(b, hard, 1<<10) }
-func BenchmarkMatchHard_32K(b *testing.B)   { benchmark(b, hard, 32<<10) }
-func BenchmarkMatchHard_1M(b *testing.B)    { benchmark(b, hard, 1<<20) }
-func BenchmarkMatchHard_32M(b *testing.B)   { benchmark(b, hard, 32<<20) }
+var benchSizes = []struct {
+	name string
+	n    int
+}{
+	{"32", 32},
+	{"1K", 1 << 10},
+	{"32K", 32 << 10},
+	{"1M", 1 << 20},
+	{"32M", 32 << 20},
+}
 
 func TestLongest(t *testing.T) {
 	re, err := Compile(`a(|b)`)
diff --git a/libgo/go/regexp/onepass.go b/libgo/go/regexp/onepass.go
index 2ce3902388b..49919548201 100644
--- a/libgo/go/regexp/onepass.go
+++ b/libgo/go/regexp/onepass.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -33,7 +33,7 @@ type onePassInst struct {
 }
 
 // OnePassPrefix returns a literal string that all matches for the
-// regexp must start with.  Complete is true if the prefix
+// regexp must start with. Complete is true if the prefix
 // is the entire match. Pc is the index of the last rune instruction
 // in the string. The OnePassPrefix skips over the mandatory
 // EmptyBeginText
@@ -450,7 +450,7 @@ func makeOnePass(p *onePassProg) *onePassProg {
 	for !instQueue.empty() {
 		visitQueue.clear()
 		pc := instQueue.next()
-		if !check(uint32(pc), m) {
+		if !check(pc, m) {
 			p = notOnePass
 			break
 		}
diff --git a/libgo/go/regexp/onepass_test.go b/libgo/go/regexp/onepass_test.go
index 8202ebefa59..f4e336c43ba 100644
--- a/libgo/go/regexp/onepass_test.go
+++ b/libgo/go/regexp/onepass_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -133,8 +133,6 @@ func TestMergeRuneSet(t *testing.T) {
 	}
 }
 
-const noStr = `!`
-
 var onePass = &onePassProg{}
 
 var onePassTests = []struct {
diff --git a/libgo/go/regexp/regexp.go b/libgo/go/regexp/regexp.go
index d7d0edb993f..fe3db9f78b0 100644
--- a/libgo/go/regexp/regexp.go
+++ b/libgo/go/regexp/regexp.go
@@ -22,14 +22,14 @@
 // All characters are UTF-8-encoded code points.
 //
 // There are 16 methods of Regexp that match a regular expression and identify
-// the matched text.  Their names are matched by this regular expression:
+// the matched text. Their names are matched by this regular expression:
 //
 //	Find(All)?(String)?(Submatch)?(Index)?
 //
 // If 'All' is present, the routine matches successive non-overlapping
-// matches of the entire expression.  Empty matches abutting a preceding
-// match are ignored.  The return value is a slice containing the successive
-// return values of the corresponding non-'All' routine.  These routines take
+// matches of the entire expression. Empty matches abutting a preceding
+// match are ignored. The return value is a slice containing the successive
+// return values of the corresponding non-'All' routine. These routines take
 // an extra integer argument, n; if n >= 0, the function returns at most n
 // matches/submatches.
 //
@@ -45,9 +45,9 @@
 //
 // If 'Index' is present, matches and submatches are identified by byte index
 // pairs within the input string: result[2*n:2*n+1] identifies the indexes of
-// the nth submatch.  The pair for n==0 identifies the match of the entire
-// expression.  If 'Index' is not present, the match is identified by the
-// text of the match/submatch.  If an index is negative, it means that
+// the nth submatch. The pair for n==0 identifies the match of the entire
+// expression. If 'Index' is not present, the match is identified by the
+// text of the match/submatch. If an index is negative, it means that
 // subexpression did not match any string in the input.
 //
 // There is also a subset of the methods that can be applied to text read
@@ -55,7 +55,7 @@
 //
 //	MatchReader, FindReaderIndex, FindReaderSubmatchIndex
 //
-// This set may grow.  Note that regular expression matches may need to
+// This set may grow. Note that regular expression matches may need to
 // examine text beyond the text returned by a match, so the methods that
 // match text from a RuneReader may read arbitrarily far into the input
 // before returning.
@@ -75,12 +75,18 @@ import (
 	"unicode/utf8"
 )
 
-var debug = false
-
 // Regexp is the representation of a compiled regular expression.
 // A Regexp is safe for concurrent use by multiple goroutines.
 type Regexp struct {
 	// read-only after Compile
+	regexpRO
+
+	// cache of machines for running regexp
+	mu      sync.Mutex
+	machine []*machine
+}
+
+type regexpRO struct {
 	expr           string         // as passed to Compile
 	prog           *syntax.Prog   // compiled program
 	onepass        *onePassProg   // onepass program or nil
@@ -93,10 +99,6 @@ type Regexp struct {
 	numSubexp      int
 	subexpNames    []string
 	longest        bool
-
-	// cache of machines for running regexp
-	mu      sync.Mutex
-	machine []*machine
 }
 
 // String returns the source text used to compile the regular expression.
@@ -109,10 +111,11 @@ func (re *Regexp) String() string {
 // When using a Regexp in multiple goroutines, giving each goroutine
 // its own copy helps to avoid lock contention.
 func (re *Regexp) Copy() *Regexp {
-	r := *re
-	r.mu = sync.Mutex{}
-	r.machine = nil
-	return &r
+	// It is not safe to copy Regexp by value
+	// since it contains a sync.Mutex.
+	return &Regexp{
+		regexpRO: re.regexpRO,
+	}
 }
 
 // Compile parses a regular expression and returns, if successful,
@@ -174,13 +177,15 @@ func compile(expr string, mode syntax.Flags, longest bool) (*Regexp, error) {
 		return nil, err
 	}
 	regexp := &Regexp{
-		expr:        expr,
-		prog:        prog,
-		onepass:     compileOnePass(prog),
-		numSubexp:   maxCap,
-		subexpNames: capNames,
-		cond:        prog.StartCond(),
-		longest:     longest,
+		regexpRO: regexpRO{
+			expr:        expr,
+			prog:        prog,
+			onepass:     compileOnePass(prog),
+			numSubexp:   maxCap,
+			subexpNames: capNames,
+			cond:        prog.StartCond(),
+			longest:     longest,
+		},
 	}
 	if regexp.onepass == notOnePass {
 		regexp.prefix, regexp.prefixComplete = prog.Prefix()
@@ -258,10 +263,10 @@ func (re *Regexp) NumSubexp() int {
 }
 
 // SubexpNames returns the names of the parenthesized subexpressions
-// in this Regexp.  The name for the first sub-expression is names[1],
+// in this Regexp. The name for the first sub-expression is names[1],
 // so that if m is a match slice, the name for m[i] is SubexpNames()[i].
 // Since the Regexp as a whole cannot be named, names[0] is always
-// the empty string.  The slice should not be modified.
+// the empty string. The slice should not be modified.
 func (re *Regexp) SubexpNames() []string {
 	return re.subexpNames
 }
@@ -394,7 +399,7 @@ func (i *inputReader) context(pos int) syntax.EmptyOp {
 }
 
 // LiteralPrefix returns a literal string that must begin any match
-// of the regular expression re.  It returns the boolean true if the
+// of the regular expression re. It returns the boolean true if the
 // literal string comprises the entire regular expression.
 func (re *Regexp) LiteralPrefix() (prefix string, complete bool) {
 	return re.prefix, re.prefixComplete
@@ -417,7 +422,7 @@ func (re *Regexp) Match(b []byte) bool {
 }
 
 // MatchReader checks whether a textual regular expression matches the text
-// read by the RuneReader.  More complicated queries need to use Compile and
+// read by the RuneReader. More complicated queries need to use Compile and
 // the full Regexp interface.
 func MatchReader(pattern string, r io.RuneReader) (matched bool, err error) {
 	re, err := Compile(pattern)
@@ -428,7 +433,7 @@ func MatchReader(pattern string, r io.RuneReader) (matched bool, err error) {
 }
 
 // MatchString checks whether a textual regular expression
-// matches a string.  More complicated queries need
+// matches a string. More complicated queries need
 // to use Compile and the full Regexp interface.
 func MatchString(pattern string, s string) (matched bool, err error) {
 	re, err := Compile(pattern)
@@ -439,7 +444,7 @@ func MatchString(pattern string, s string) (matched bool, err error) {
 }
 
 // Match checks whether a textual regular expression
-// matches a byte slice.  More complicated queries need
+// matches a byte slice. More complicated queries need
 // to use Compile and the full Regexp interface.
 func Match(pattern string, b []byte) (matched bool, err error) {
 	re, err := Compile(pattern)
@@ -450,11 +455,11 @@ func Match(pattern string, b []byte) (matched bool, err error) {
 }
 
 // ReplaceAllString returns a copy of src, replacing matches of the Regexp
-// with the replacement string repl.  Inside repl, $ signs are interpreted as
+// with the replacement string repl. Inside repl, $ signs are interpreted as
 // in Expand, so for instance $1 represents the text of the first submatch.
 func (re *Regexp) ReplaceAllString(src, repl string) string {
 	n := 2
-	if strings.Index(repl, "$") >= 0 {
+	if strings.Contains(repl, "$") {
 		n = 2 * (re.numSubexp + 1)
 	}
 	b := re.replaceAll(nil, src, n, func(dst []byte, match []int) []byte {
@@ -464,7 +469,7 @@ func (re *Regexp) ReplaceAllString(src, repl string) string {
 }
 
 // ReplaceAllLiteralString returns a copy of src, replacing matches of the Regexp
-// with the replacement string repl.  The replacement repl is substituted directly,
+// with the replacement string repl. The replacement repl is substituted directly,
 // without using Expand.
 func (re *Regexp) ReplaceAllLiteralString(src, repl string) string {
 	return string(re.replaceAll(nil, src, 2, func(dst []byte, match []int) []byte {
@@ -474,7 +479,7 @@ func (re *Regexp) ReplaceAllLiteralString(src, repl string) string {
 
 // ReplaceAllStringFunc returns a copy of src in which all matches of the
 // Regexp have been replaced by the return value of function repl applied
-// to the matched substring.  The replacement returned by repl is substituted
+// to the matched substring. The replacement returned by repl is substituted
 // directly, without using Expand.
 func (re *Regexp) ReplaceAllStringFunc(src string, repl func(string) string) string {
 	b := re.replaceAll(nil, src, 2, func(dst []byte, match []int) []byte {
@@ -530,7 +535,7 @@ func (re *Regexp) replaceAll(bsrc []byte, src string, nmatch int, repl func(dst
 			searchPos += width
 		} else if searchPos+1 > a[1] {
 			// This clause is only needed at the end of the input
-			// string.  In that case, DecodeRuneInString returns width=0.
+			// string. In that case, DecodeRuneInString returns width=0.
 			searchPos++
 		} else {
 			searchPos = a[1]
@@ -548,7 +553,7 @@ func (re *Regexp) replaceAll(bsrc []byte, src string, nmatch int, repl func(dst
 }
 
 // ReplaceAll returns a copy of src, replacing matches of the Regexp
-// with the replacement text repl.  Inside repl, $ signs are interpreted as
+// with the replacement text repl. Inside repl, $ signs are interpreted as
 // in Expand, so for instance $1 represents the text of the first submatch.
 func (re *Regexp) ReplaceAll(src, repl []byte) []byte {
 	n := 2
@@ -566,7 +571,7 @@ func (re *Regexp) ReplaceAll(src, repl []byte) []byte {
 }
 
 // ReplaceAllLiteral returns a copy of src, replacing matches of the Regexp
-// with the replacement bytes repl.  The replacement repl is substituted directly,
+// with the replacement bytes repl. The replacement repl is substituted directly,
 // without using Expand.
 func (re *Regexp) ReplaceAllLiteral(src, repl []byte) []byte {
 	return re.replaceAll(src, "", 2, func(dst []byte, match []int) []byte {
@@ -576,7 +581,7 @@ func (re *Regexp) ReplaceAllLiteral(src, repl []byte) []byte {
 
 // ReplaceAllFunc returns a copy of src in which all matches of the
 // Regexp have been replaced by the return value of function repl applied
-// to the matched byte slice.  The replacement returned by repl is substituted
+// to the matched byte slice. The replacement returned by repl is substituted
 // directly, without using Expand.
 func (re *Regexp) ReplaceAllFunc(src []byte, repl func([]byte) []byte) []byte {
 	return re.replaceAll(src, "", 2, func(dst []byte, match []int) []byte {
@@ -592,7 +597,7 @@ func special(b byte) bool {
 
 // QuoteMeta returns a string that quotes all regular expression metacharacters
 // inside the argument text; the returned string is a regular expression matching
-// the literal text.  For example, QuoteMeta(`[foo]`) returns `\[foo\]`.
+// the literal text. For example, QuoteMeta(`[foo]`) returns `\[foo\]`.
 func QuoteMeta(s string) string {
 	b := make([]byte, 2*len(s))
 
@@ -684,7 +689,7 @@ func (re *Regexp) Find(b []byte) []byte {
 }
 
 // FindIndex returns a two-element slice of integers defining the location of
-// the leftmost match in b of the regular expression.  The match itself is at
+// the leftmost match in b of the regular expression. The match itself is at
 // b[loc[0]:loc[1]].
 // A return value of nil indicates no match.
 func (re *Regexp) FindIndex(b []byte) (loc []int) {
@@ -696,9 +701,9 @@ func (re *Regexp) FindIndex(b []byte) (loc []int) {
 }
 
 // FindString returns a string holding the text of the leftmost match in s of the regular
-// expression.  If there is no match, the return value is an empty string,
+// expression. If there is no match, the return value is an empty string,
 // but it will also be empty if the regular expression successfully matches
-// an empty string.  Use FindStringIndex or FindStringSubmatch if it is
+// an empty string. Use FindStringIndex or FindStringSubmatch if it is
 // necessary to distinguish these cases.
 func (re *Regexp) FindString(s string) string {
 	a := re.doExecute(nil, nil, s, 0, 2)
@@ -709,7 +714,7 @@ func (re *Regexp) FindString(s string) string {
 }
 
 // FindStringIndex returns a two-element slice of integers defining the
-// location of the leftmost match in s of the regular expression.  The match
+// location of the leftmost match in s of the regular expression. The match
 // itself is at s[loc[0]:loc[1]].
 // A return value of nil indicates no match.
 func (re *Regexp) FindStringIndex(s string) (loc []int) {
@@ -722,7 +727,7 @@ func (re *Regexp) FindStringIndex(s string) (loc []int) {
 
 // FindReaderIndex returns a two-element slice of integers defining the
 // location of the leftmost match of the regular expression in text read from
-// the RuneReader.  The match text was found in the input stream at
+// the RuneReader. The match text was found in the input stream at
 // byte offset loc[0] through loc[1]-1.
 // A return value of nil indicates no match.
 func (re *Regexp) FindReaderIndex(r io.RuneReader) (loc []int) {
@@ -754,14 +759,14 @@ func (re *Regexp) FindSubmatch(b []byte) [][]byte {
 
 // Expand appends template to dst and returns the result; during the
 // append, Expand replaces variables in the template with corresponding
-// matches drawn from src.  The match slice should have been returned by
+// matches drawn from src. The match slice should have been returned by
 // FindSubmatchIndex.
 //
 // In the template, a variable is denoted by a substring of the form
 // $name or ${name}, where name is a non-empty sequence of letters,
-// digits, and underscores.  A purely numeric name like $1 refers to
+// digits, and underscores. A purely numeric name like $1 refers to
 // the submatch with the corresponding index; other names refer to
-// capturing parentheses named with the (?P<name>...) syntax.  A
+// capturing parentheses named with the (?P<name>...) syntax. A
 // reference to an out of range or unmatched index or a name that is not
 // present in the regular expression is replaced with an empty slice.
 //
@@ -920,7 +925,7 @@ func (re *Regexp) FindStringSubmatchIndex(s string) []int {
 // FindReaderSubmatchIndex returns a slice holding the index pairs
 // identifying the leftmost match of the regular expression of text read by
 // the RuneReader, and the matches, if any, of its subexpressions, as defined
-// by the 'Submatch' and 'Index' descriptions in the package comment.  A
+// by the 'Submatch' and 'Index' descriptions in the package comment. A
 // return value of nil indicates no match.
 func (re *Regexp) FindReaderSubmatchIndex(r io.RuneReader) []int {
 	return re.pad(re.doExecute(r, nil, "", 0, re.prog.NumCap))
diff --git a/libgo/go/regexp/syntax/compile.go b/libgo/go/regexp/syntax/compile.go
index 95f6f15698d..83e53ba6ca0 100644
--- a/libgo/go/regexp/syntax/compile.go
+++ b/libgo/go/regexp/syntax/compile.go
@@ -8,11 +8,11 @@ import "unicode"
 
 // A patchList is a list of instruction pointers that need to be filled in (patched).
 // Because the pointers haven't been filled in yet, we can reuse their storage
-// to hold the list.  It's kind of sleazy, but works well in practice.
+// to hold the list. It's kind of sleazy, but works well in practice.
 // See http://swtch.com/~rsc/regexp/regexp1.html for inspiration.
 //
 // These aren't really pointers: they're integers, so we can reinterpret them
-// this way without using package unsafe.  A value l denotes
+// this way without using package unsafe. A value l denotes
 // p.inst[l>>1].Out (l&1==0) or .Arg (l&1==1).
 // l == 0 denotes the empty list, okay because we start every program
 // with a fail instruction, so we'll never want to point at its output link.
diff --git a/libgo/go/regexp/syntax/doc.go b/libgo/go/regexp/syntax/doc.go
index e5e71f14f59..efc0b435711 100644
--- a/libgo/go/regexp/syntax/doc.go
+++ b/libgo/go/regexp/syntax/doc.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -66,7 +66,7 @@ Grouping:
 
 Empty strings:
   ^              at beginning of text or line (flag m=true)
-  $              at end of text (like \z not \Z) or line (flag m=true)
+  $              at end of text (like \z not Perl's \Z) or line (flag m=true)
   \A             at beginning of text
   \b             at ASCII word boundary (\w on one side and \W, \A, or \z on the other)
   \B             not at ASCII word boundary
diff --git a/libgo/go/regexp/syntax/parse.go b/libgo/go/regexp/syntax/parse.go
index f38bbf66e3c..7b8be55ddb1 100644
--- a/libgo/go/regexp/syntax/parse.go
+++ b/libgo/go/regexp/syntax/parse.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -141,9 +141,9 @@ func (p *parser) push(re *Regexp) *Regexp {
 }
 
 // maybeConcat implements incremental concatenation
-// of literal runes into string nodes.  The parser calls this
+// of literal runes into string nodes. The parser calls this
 // before each push, so only the top fragment of the stack
-// might need processing.  Since this is called before a push,
+// might need processing. Since this is called before a push,
 // the topmost literal is no longer subject to operators like *
 // (Otherwise ab* would turn into (ab)*.)
 // If r >= 0 and there's a node left over, maybeConcat uses it
@@ -600,7 +600,7 @@ func (p *parser) leadingString(re *Regexp) ([]rune, Flags) {
 }
 
 // removeLeadingString removes the first n leading runes
-// from the beginning of re.  It returns the replacement for re.
+// from the beginning of re. It returns the replacement for re.
 func (p *parser) removeLeadingString(re *Regexp, n int) *Regexp {
 	if re.Op == OpConcat && len(re.Sub) > 0 {
 		// Removing a leading string in a concatenation
@@ -957,11 +957,11 @@ func (p *parser) parsePerlFlags(s string) (rest string, err error) {
 	// Perl 5.10 gave in and implemented the Python version too,
 	// but they claim that the last two are the preferred forms.
 	// PCRE and languages based on it (specifically, PHP and Ruby)
-	// support all three as well.  EcmaScript 4 uses only the Python form.
+	// support all three as well. EcmaScript 4 uses only the Python form.
 	//
 	// In both the open source world (via Code Search) and the
 	// Google source tree, (?P<expr>name) is the dominant form,
-	// so that's the one we implement.  One is enough.
+	// so that's the one we implement. One is enough.
 	if len(t) > 4 && t[2] == 'P' && t[3] == '<' {
 		// Pull out name.
 		end := strings.IndexRune(t, '>')
@@ -989,7 +989,7 @@ func (p *parser) parsePerlFlags(s string) (rest string, err error) {
 		return t[end+1:], nil
 	}
 
-	// Non-capturing group.  Might also twiddle Perl flags.
+	// Non-capturing group. Might also twiddle Perl flags.
 	var c rune
 	t = t[2:] // skip (?
 	flags := p.flags
@@ -1257,7 +1257,7 @@ Switch:
 		if c < utf8.RuneSelf && !isalnum(c) {
 			// Escaped non-word characters are always themselves.
 			// PCRE is not quite so rigorous: it accepts things like
-			// \q, but we don't.  We once rejected \_, but too many
+			// \q, but we don't. We once rejected \_, but too many
 			// programs and people insist on using it, so allow \_.
 			return c, t, nil
 		}
@@ -1292,7 +1292,7 @@ Switch:
 		if c == '{' {
 			// Any number of digits in braces.
 			// Perl accepts any text at all; it ignores all text
-			// after the first non-hex digit.  We require only hex digits,
+			// after the first non-hex digit. We require only hex digits,
 			// and at least one.
 			nhex := 0
 			r = 0
@@ -1333,10 +1333,10 @@ Switch:
 		}
 		return x*16 + y, t, nil
 
-	// C escapes.  There is no case 'b', to avoid misparsing
+	// C escapes. There is no case 'b', to avoid misparsing
 	// the Perl word-boundary \b as the C backspace \b
-	// when in POSIX mode.  In Perl, /\b/ means word-boundary
-	// but /[\b]/ means backspace.  We don't support that.
+	// when in POSIX mode. In Perl, /\b/ means word-boundary
+	// but /[\b]/ means backspace. We don't support that.
 	// If you want a backspace, embed a literal backspace
 	// character or use \x08.
 	case 'a':
@@ -1377,7 +1377,7 @@ type charGroup struct {
 }
 
 // parsePerlClassEscape parses a leading Perl character class escape like \d
-// from the beginning of s.  If one is present, it appends the characters to r
+// from the beginning of s. If one is present, it appends the characters to r
 // and returns the new slice r and the remainder of the string.
 func (p *parser) parsePerlClassEscape(s string, r []rune) (out []rune, rest string) {
 	if p.flags&PerlX == 0 || len(s) < 2 || s[0] != '\\' {
@@ -1391,7 +1391,7 @@ func (p *parser) parsePerlClassEscape(s string, r []rune) (out []rune, rest stri
 }
 
 // parseNamedClass parses a leading POSIX named character class like [:alnum:]
-// from the beginning of s.  If one is present, it appends the characters to r
+// from the beginning of s. If one is present, it appends the characters to r
 // and returns the new slice r and the remainder of the string.
 func (p *parser) parseNamedClass(s string, r []rune) (out []rune, rest string, err error) {
 	if len(s) < 2 || s[0] != '[' || s[1] != ':' {
@@ -1454,7 +1454,7 @@ func unicodeTable(name string) (*unicode.RangeTable, *unicode.RangeTable) {
 }
 
 // parseUnicodeClass parses a leading Unicode character class like \p{Han}
-// from the beginning of s.  If one is present, it appends the characters to r
+// from the beginning of s. If one is present, it appends the characters to r
 // and returns the new slice r and the remainder of the string.
 func (p *parser) parseUnicodeClass(s string, r []rune) (out []rune, rest string, err error) {
 	if p.flags&UnicodeGroups == 0 || len(s) < 2 || s[0] != '\\' || s[1] != 'p' && s[1] != 'P' {
@@ -1692,7 +1692,7 @@ const (
 	// minimum and maximum runes involved in folding.
 	// checked during test.
 	minFold = 0x0041
-	maxFold = 0x118df
+	maxFold = 0x1e943
 )
 
 // appendFoldedRange returns the result of appending the range lo-hi
@@ -1718,7 +1718,7 @@ func appendFoldedRange(r []rune, lo, hi rune) []rune {
 		hi = maxFold
 	}
 
-	// Brute force.  Depend on appendRange to coalesce ranges on the fly.
+	// Brute force. Depend on appendRange to coalesce ranges on the fly.
 	for c := lo; c <= hi; c++ {
 		r = appendRange(r, c, c)
 		f := unicode.SimpleFold(c)
diff --git a/libgo/go/regexp/syntax/parse_test.go b/libgo/go/regexp/syntax/parse_test.go
index 5ca54bbe1eb..dd6529f7c8c 100644
--- a/libgo/go/regexp/syntax/parse_test.go
+++ b/libgo/go/regexp/syntax/parse_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/regexp/syntax/prog.go b/libgo/go/regexp/syntax/prog.go
index ae6db31a441..c32ae8d9fac 100644
--- a/libgo/go/regexp/syntax/prog.go
+++ b/libgo/go/regexp/syntax/prog.go
@@ -144,7 +144,7 @@ func (i *Inst) op() InstOp {
 }
 
 // Prefix returns a literal string that all matches for the
-// regexp must start with.  Complete is true if the prefix
+// regexp must start with. Complete is true if the prefix
 // is the entire match.
 func (p *Prog) Prefix() (prefix string, complete bool) {
 	i, _ := p.skipNop(uint32(p.Start))
@@ -164,7 +164,7 @@ func (p *Prog) Prefix() (prefix string, complete bool) {
 }
 
 // StartCond returns the leading empty-width conditions that must
-// be true in any match.  It returns ^EmptyOp(0) if no matches are possible.
+// be true in any match. It returns ^EmptyOp(0) if no matches are possible.
 func (p *Prog) StartCond() EmptyOp {
 	var flag EmptyOp
 	pc := uint32(p.Start)
diff --git a/libgo/go/regexp/syntax/regexp.go b/libgo/go/regexp/syntax/regexp.go
index 75822cf981e..0fe9269f255 100644
--- a/libgo/go/regexp/syntax/regexp.go
+++ b/libgo/go/regexp/syntax/regexp.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -139,7 +139,7 @@ func writeRegexp(b *bytes.Buffer, re *Regexp) {
 		if len(re.Rune) == 0 {
 			b.WriteString(`^\x00-\x{10FFFF}`)
 		} else if re.Rune[0] == 0 && re.Rune[len(re.Rune)-1] == unicode.MaxRune {
-			// Contains 0 and MaxRune.  Probably a negated class.
+			// Contains 0 and MaxRune. Probably a negated class.
 			// Print the gaps.
 			b.WriteRune('^')
 			for i := 1; i < len(re.Rune)-1; i += 2 {
@@ -252,7 +252,7 @@ const meta = `\.+*?()|[]{}^$`
 
 func escape(b *bytes.Buffer, r rune, force bool) {
 	if unicode.IsPrint(r) {
-		if strings.IndexRune(meta, r) >= 0 || force {
+		if strings.ContainsRune(meta, r) || force {
 			b.WriteRune('\\')
 		}
 		b.WriteRune(r)
diff --git a/libgo/go/regexp/syntax/simplify.go b/libgo/go/regexp/syntax/simplify.go
index 72390417bbe..e4393251399 100644
--- a/libgo/go/regexp/syntax/simplify.go
+++ b/libgo/go/regexp/syntax/simplify.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,7 +8,7 @@ package syntax
 // and with various other simplifications, such as rewriting /(?:a+)+/ to /a+/.
 // The resulting regexp will execute correctly but its string representation
 // will not produce the same parse tree, because capturing parentheses
-// may have been duplicated or removed.  For example, the simplified form
+// may have been duplicated or removed. For example, the simplified form
 // for /(x){1,2}/ is /(x)(x)?/ but both parentheses capture as $1.
 // The returned regexp may share structure with or be the original.
 func (re *Regexp) Simplify() *Regexp {
@@ -117,13 +117,13 @@ func (re *Regexp) Simplify() *Regexp {
 }
 
 // simplify1 implements Simplify for the unary OpStar,
-// OpPlus, and OpQuest operators.  It returns the simple regexp
+// OpPlus, and OpQuest operators. It returns the simple regexp
 // equivalent to
 //
 //	Regexp{Op: op, Flags: flags, Sub: {sub}}
 //
 // under the assumption that sub is already simple, and
-// without first allocating that structure.  If the regexp
+// without first allocating that structure. If the regexp
 // to be returned turns out to be equivalent to re, simplify1
 // returns re instead.
 //
diff --git a/libgo/go/regexp/syntax/simplify_test.go b/libgo/go/regexp/syntax/simplify_test.go
index 5d0f1dea5e7..9877db3d0a3 100644
--- a/libgo/go/regexp/syntax/simplify_test.go
+++ b/libgo/go/regexp/syntax/simplify_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -59,7 +59,7 @@ var simplifyTests = []struct {
 	{`a{0,1}`, `a?`},
 	// The next three are illegible because Simplify inserts (?:)
 	// parens instead of () parens to avoid creating extra
-	// captured subexpressions.  The comments show a version with fewer parens.
+	// captured subexpressions. The comments show a version with fewer parens.
 	{`(a){0,2}`, `(?:(a)(a)?)?`},                       //       (aa?)?
 	{`(a){0,4}`, `(?:(a)(?:(a)(?:(a)(a)?)?)?)?`},       //   (a(a(aa?)?)?)?
 	{`(a){2,6}`, `(a)(a)(?:(a)(?:(a)(?:(a)(a)?)?)?)?`}, // aa(a(a(aa?)?)?)?
@@ -117,7 +117,7 @@ var simplifyTests = []struct {
 	// Empty string as a regular expression.
 	// The empty string must be preserved inside parens in order
 	// to make submatches work right, so these tests are less
-	// interesting than they might otherwise be.  String inserts
+	// interesting than they might otherwise be. String inserts
 	// explicit (?:) in place of non-parenthesized empty strings,
 	// to make them easier to spot for other parsers.
 	{`(a|b|)`, `([a-b]|(?:))`},
diff --git a/libgo/go/runtime/append_test.go b/libgo/go/runtime/append_test.go
index a67dc9b4948..6b8968e382d 100644
--- a/libgo/go/runtime/append_test.go
+++ b/libgo/go/runtime/append_test.go
@@ -3,10 +3,59 @@
 // license that can be found in the LICENSE file.
 package runtime_test
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+)
 
 const N = 20
 
+func BenchmarkMakeSlice(b *testing.B) {
+	var x []byte
+	for i := 0; i < b.N; i++ {
+		x = make([]byte, 32)
+		_ = x
+	}
+}
+
+func BenchmarkGrowSliceBytes(b *testing.B) {
+	b.StopTimer()
+	var x = make([]byte, 9)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		_ = append([]byte(nil), x...)
+	}
+}
+
+func BenchmarkGrowSliceInts(b *testing.B) {
+	b.StopTimer()
+	var x = make([]int, 9)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		_ = append([]int(nil), x...)
+	}
+}
+
+func BenchmarkGrowSlicePtr(b *testing.B) {
+	b.StopTimer()
+	var x = make([]*byte, 9)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		_ = append([]*byte(nil), x...)
+	}
+}
+
+type struct24 struct{ a, b, c int64 }
+
+func BenchmarkGrowSliceStruct24Bytes(b *testing.B) {
+	b.StopTimer()
+	var x = make([]struct24, 9)
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		_ = append([]struct24(nil), x...)
+	}
+}
+
 func BenchmarkAppend(b *testing.B) {
 	b.StopTimer()
 	x := make([]int, 0, N)
@@ -38,75 +87,37 @@ func BenchmarkAppendGrowString(b *testing.B) {
 	}
 }
 
-func benchmarkAppendBytes(b *testing.B, length int) {
-	b.StopTimer()
-	x := make([]byte, 0, N)
-	y := make([]byte, length)
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		x = x[0:0]
-		x = append(x, y...)
+func BenchmarkAppendSlice(b *testing.B) {
+	for _, length := range []int{1, 4, 7, 8, 15, 16, 32} {
+		b.Run(fmt.Sprint(length, "Bytes"), func(b *testing.B) {
+			x := make([]byte, 0, N)
+			y := make([]byte, length)
+			for i := 0; i < b.N; i++ {
+				x = x[0:0]
+				x = append(x, y...)
+			}
+		})
 	}
 }
 
-func BenchmarkAppend1Byte(b *testing.B) {
-	benchmarkAppendBytes(b, 1)
-}
-
-func BenchmarkAppend4Bytes(b *testing.B) {
-	benchmarkAppendBytes(b, 4)
-}
-
-func BenchmarkAppend7Bytes(b *testing.B) {
-	benchmarkAppendBytes(b, 7)
-}
-
-func BenchmarkAppend8Bytes(b *testing.B) {
-	benchmarkAppendBytes(b, 8)
-}
-
-func BenchmarkAppend15Bytes(b *testing.B) {
-	benchmarkAppendBytes(b, 15)
-}
-
-func BenchmarkAppend16Bytes(b *testing.B) {
-	benchmarkAppendBytes(b, 16)
-}
-
-func BenchmarkAppend32Bytes(b *testing.B) {
-	benchmarkAppendBytes(b, 32)
-}
-
-func benchmarkAppendStr(b *testing.B, str string) {
-	b.StopTimer()
-	x := make([]byte, 0, N)
-	b.StartTimer()
-	for i := 0; i < b.N; i++ {
-		x = x[0:0]
-		x = append(x, str...)
+func BenchmarkAppendStr(b *testing.B) {
+	for _, str := range []string{
+		"1",
+		"1234",
+		"12345678",
+		"1234567890123456",
+		"12345678901234567890123456789012",
+	} {
+		b.Run(fmt.Sprint(len(str), "Bytes"), func(b *testing.B) {
+			x := make([]byte, 0, N)
+			for i := 0; i < b.N; i++ {
+				x = x[0:0]
+				x = append(x, str...)
+			}
+		})
 	}
 }
 
-func BenchmarkAppendStr1Byte(b *testing.B) {
-	benchmarkAppendStr(b, "1")
-}
-
-func BenchmarkAppendStr4Bytes(b *testing.B) {
-	benchmarkAppendStr(b, "1234")
-}
-
-func BenchmarkAppendStr8Bytes(b *testing.B) {
-	benchmarkAppendStr(b, "12345678")
-}
-
-func BenchmarkAppendStr16Bytes(b *testing.B) {
-	benchmarkAppendStr(b, "1234567890123456")
-}
-
-func BenchmarkAppendStr32Bytes(b *testing.B) {
-	benchmarkAppendStr(b, "12345678901234567890123456789012")
-}
-
 func BenchmarkAppendSpecialCase(b *testing.B) {
 	b.StopTimer()
 	x := make([]int, 0, N)
@@ -149,42 +160,153 @@ func TestAppendOverlap(t *testing.T) {
 	}
 }
 
-func benchmarkCopySlice(b *testing.B, l int) {
-	s := make([]byte, l)
-	buf := make([]byte, 4096)
-	var n int
-	for i := 0; i < b.N; i++ {
-		n = copy(buf, s)
+func BenchmarkCopy(b *testing.B) {
+	for _, l := range []int{1, 2, 4, 8, 12, 16, 32, 128, 1024} {
+		buf := make([]byte, 4096)
+		b.Run(fmt.Sprint(l, "Byte"), func(b *testing.B) {
+			s := make([]byte, l)
+			var n int
+			for i := 0; i < b.N; i++ {
+				n = copy(buf, s)
+			}
+			b.SetBytes(int64(n))
+		})
+		b.Run(fmt.Sprint(l, "String"), func(b *testing.B) {
+			s := string(make([]byte, l))
+			var n int
+			for i := 0; i < b.N; i++ {
+				n = copy(buf, s)
+			}
+			b.SetBytes(int64(n))
+		})
 	}
-	b.SetBytes(int64(n))
 }
 
-func benchmarkCopyStr(b *testing.B, l int) {
-	s := string(make([]byte, l))
-	buf := make([]byte, 4096)
-	var n int
-	for i := 0; i < b.N; i++ {
-		n = copy(buf, s)
-	}
-	b.SetBytes(int64(n))
-}
-
-func BenchmarkCopy1Byte(b *testing.B)    { benchmarkCopySlice(b, 1) }
-func BenchmarkCopy2Byte(b *testing.B)    { benchmarkCopySlice(b, 2) }
-func BenchmarkCopy4Byte(b *testing.B)    { benchmarkCopySlice(b, 4) }
-func BenchmarkCopy8Byte(b *testing.B)    { benchmarkCopySlice(b, 8) }
-func BenchmarkCopy12Byte(b *testing.B)   { benchmarkCopySlice(b, 12) }
-func BenchmarkCopy16Byte(b *testing.B)   { benchmarkCopySlice(b, 16) }
-func BenchmarkCopy32Byte(b *testing.B)   { benchmarkCopySlice(b, 32) }
-func BenchmarkCopy128Byte(b *testing.B)  { benchmarkCopySlice(b, 128) }
-func BenchmarkCopy1024Byte(b *testing.B) { benchmarkCopySlice(b, 1024) }
-
-func BenchmarkCopy1String(b *testing.B)    { benchmarkCopyStr(b, 1) }
-func BenchmarkCopy2String(b *testing.B)    { benchmarkCopyStr(b, 2) }
-func BenchmarkCopy4String(b *testing.B)    { benchmarkCopyStr(b, 4) }
-func BenchmarkCopy8String(b *testing.B)    { benchmarkCopyStr(b, 8) }
-func BenchmarkCopy12String(b *testing.B)   { benchmarkCopyStr(b, 12) }
-func BenchmarkCopy16String(b *testing.B)   { benchmarkCopyStr(b, 16) }
-func BenchmarkCopy32String(b *testing.B)   { benchmarkCopyStr(b, 32) }
-func BenchmarkCopy128String(b *testing.B)  { benchmarkCopyStr(b, 128) }
-func BenchmarkCopy1024String(b *testing.B) { benchmarkCopyStr(b, 1024) }
+var (
+	sByte []byte
+	s1Ptr []uintptr
+	s2Ptr [][2]uintptr
+	s3Ptr [][3]uintptr
+	s4Ptr [][4]uintptr
+)
+
+// BenchmarkAppendInPlace tests the performance of append
+// when the result is being written back to the same slice.
+// In order for the in-place optimization to occur,
+// the slice must be referred to by address;
+// using a global is an easy way to trigger that.
+// We test the "grow" and "no grow" paths separately,
+// but not the "normal" (occasionally grow) path,
+// because it is a blend of the other two.
+// We use small numbers and small sizes in an attempt
+// to avoid benchmarking memory allocation and copying.
+// We use scalars instead of pointers in an attempt
+// to avoid benchmarking the write barriers.
+// We benchmark four common sizes (byte, pointer, string/interface, slice),
+// and one larger size.
+func BenchmarkAppendInPlace(b *testing.B) {
+	b.Run("NoGrow", func(b *testing.B) {
+		const C = 128
+
+		b.Run("Byte", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				sByte = make([]byte, C)
+				for j := 0; j < C; j++ {
+					sByte = append(sByte, 0x77)
+				}
+			}
+		})
+
+		b.Run("1Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s1Ptr = make([]uintptr, C)
+				for j := 0; j < C; j++ {
+					s1Ptr = append(s1Ptr, 0x77)
+				}
+			}
+		})
+
+		b.Run("2Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s2Ptr = make([][2]uintptr, C)
+				for j := 0; j < C; j++ {
+					s2Ptr = append(s2Ptr, [2]uintptr{0x77, 0x88})
+				}
+			}
+		})
+
+		b.Run("3Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s3Ptr = make([][3]uintptr, C)
+				for j := 0; j < C; j++ {
+					s3Ptr = append(s3Ptr, [3]uintptr{0x77, 0x88, 0x99})
+				}
+			}
+		})
+
+		b.Run("4Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s4Ptr = make([][4]uintptr, C)
+				for j := 0; j < C; j++ {
+					s4Ptr = append(s4Ptr, [4]uintptr{0x77, 0x88, 0x99, 0xAA})
+				}
+			}
+		})
+
+	})
+
+	b.Run("Grow", func(b *testing.B) {
+		const C = 5
+
+		b.Run("Byte", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				sByte = make([]byte, 0)
+				for j := 0; j < C; j++ {
+					sByte = append(sByte, 0x77)
+					sByte = sByte[:cap(sByte)]
+				}
+			}
+		})
+
+		b.Run("1Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s1Ptr = make([]uintptr, 0)
+				for j := 0; j < C; j++ {
+					s1Ptr = append(s1Ptr, 0x77)
+					s1Ptr = s1Ptr[:cap(s1Ptr)]
+				}
+			}
+		})
+
+		b.Run("2Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s2Ptr = make([][2]uintptr, 0)
+				for j := 0; j < C; j++ {
+					s2Ptr = append(s2Ptr, [2]uintptr{0x77, 0x88})
+					s2Ptr = s2Ptr[:cap(s2Ptr)]
+				}
+			}
+		})
+
+		b.Run("3Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s3Ptr = make([][3]uintptr, 0)
+				for j := 0; j < C; j++ {
+					s3Ptr = append(s3Ptr, [3]uintptr{0x77, 0x88, 0x99})
+					s3Ptr = s3Ptr[:cap(s3Ptr)]
+				}
+			}
+		})
+
+		b.Run("4Ptr", func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				s4Ptr = make([][4]uintptr, 0)
+				for j := 0; j < C; j++ {
+					s4Ptr = append(s4Ptr, [4]uintptr{0x77, 0x88, 0x99, 0xAA})
+					s4Ptr = s4Ptr[:cap(s4Ptr)]
+				}
+			}
+		})
+
+	})
+}
diff --git a/libgo/go/runtime/callers_test.go b/libgo/go/runtime/callers_test.go
new file mode 100644
index 00000000000..ad83f9969c4
--- /dev/null
+++ b/libgo/go/runtime/callers_test.go
@@ -0,0 +1,83 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"runtime"
+	"strings"
+	"testing"
+)
+
+func f1(pan bool) []uintptr {
+	return f2(pan) // line 14
+}
+
+func f2(pan bool) []uintptr {
+	return f3(pan) // line 18
+}
+
+func f3(pan bool) []uintptr {
+	if pan {
+		panic("f3") // line 23
+	}
+	ret := make([]uintptr, 20)
+	return ret[:runtime.Callers(0, ret)] // line 26
+}
+
+func testCallers(t *testing.T, pcs []uintptr, pan bool) {
+	m := make(map[string]int, len(pcs))
+	frames := runtime.CallersFrames(pcs)
+	for {
+		frame, more := frames.Next()
+		if frame.Function != "" {
+			m[frame.Function] = frame.Line
+		}
+		if !more {
+			break
+		}
+	}
+
+	var seen []string
+	for k := range m {
+		seen = append(seen, k)
+	}
+	t.Logf("functions seen: %s", strings.Join(seen, " "))
+
+	var f3Line int
+	if pan {
+		f3Line = 23
+	} else {
+		f3Line = 26
+	}
+	want := []struct {
+		name string
+		line int
+	}{
+		{"f1", 14},
+		{"f2", 18},
+		{"f3", f3Line},
+	}
+	for _, w := range want {
+		if got := m["runtime_test."+w.name]; got != w.line {
+			t.Errorf("%s is line %d, want %d", w.name, got, w.line)
+		}
+	}
+}
+
+func TestCallers(t *testing.T) {
+	testCallers(t, f1(false), false)
+}
+
+func TestCallersPanic(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatal("did not panic")
+		}
+		pcs := make([]uintptr, 20)
+		pcs = pcs[:runtime.Callers(0, pcs)]
+		testCallers(t, pcs, true)
+	}()
+	f1(true)
+}
diff --git a/libgo/go/runtime/cgo_mips64x.go b/libgo/go/runtime/cgo_mips64x.go
new file mode 100644
index 00000000000..f718e929126
--- /dev/null
+++ b/libgo/go/runtime/cgo_mips64x.go
@@ -0,0 +1,12 @@
+// Copyright 2016 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build mips64 mips64le
+
+package runtime
+
+// crosscall1 calls into the runtime to set up the registers the
+// Go runtime expects and so the symbol it calls needs to be exported
+// for external linking to work.
+//go:cgo_export_static _cgo_reginit
diff --git a/libgo/go/runtime/cgo_mmap.go b/libgo/go/runtime/cgo_mmap.go
index c0396bdde51..a23cc79b7e3 100644
--- a/libgo/go/runtime/cgo_mmap.go
+++ b/libgo/go/runtime/cgo_mmap.go
@@ -1,8 +1,8 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Support for memory sanitizer.  See runtime/cgo/mmap.go.
+// Support for memory sanitizer. See runtime/cgo/mmap.go.
 
 // +build linux,amd64
 
@@ -32,10 +32,10 @@ func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) uns
 	return sysMmap(addr, n, prot, flags, fd, off)
 }
 
-// sysMmap calls the mmap system call.  It is implemented in assembly.
+// sysMmap calls the mmap system call. It is implemented in assembly.
 func sysMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer
 
 // cgoMmap calls the mmap function in the runtime/cgo package on the
 // callCgoMmap calls the mmap function in the runtime/cgo package
-// using the GCC calling convention.  It is implemented in assembly.
+// using the GCC calling convention. It is implemented in assembly.
 func callCgoMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) uintptr
diff --git a/libgo/go/runtime/cgo_ppc64x.go b/libgo/go/runtime/cgo_ppc64x.go
index 6a1b3bb4172..fb2da32c7e0 100644
--- a/libgo/go/runtime/cgo_ppc64x.go
+++ b/libgo/go/runtime/cgo_ppc64x.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/cgocheck.go b/libgo/go/runtime/cgocheck.go
index aebce1506d1..2d064145a41 100644
--- a/libgo/go/runtime/cgocheck.go
+++ b/libgo/go/runtime/cgocheck.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -89,17 +89,25 @@ func cgoCheckSliceCopy(typ *_type, dst, src slice, n int) {
 }
 
 // cgoCheckTypedBlock checks the block of memory at src, for up to size bytes,
-// and throws if it finds a Go pointer.  The type of the memory is typ,
+// and throws if it finds a Go pointer. The type of the memory is typ,
 // and src is off bytes into that type.
 //go:nosplit
 //go:nowritebarrier
 func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
+	// Anything past typ.ptrdata is not a pointer.
+	if typ.ptrdata <= off {
+		return
+	}
+	if ptrdataSize := typ.ptrdata - off; size > ptrdataSize {
+		size = ptrdataSize
+	}
+
 	if typ.kind&kindGCProg == 0 {
 		cgoCheckBits(src, typ.gcdata, off, size)
 		return
 	}
 
-	// The type has a GC program.  Try to find GC bits somewhere else.
+	// The type has a GC program. Try to find GC bits somewhere else.
 	for datap := &firstmoduledata; datap != nil; datap = datap.next {
 		if cgoInRange(src, datap.data, datap.edata) {
 			doff := uintptr(src) - datap.data
@@ -148,8 +156,8 @@ func cgoCheckTypedBlock(typ *_type, src unsafe.Pointer, off, size uintptr) {
 }
 
 // cgoCheckBits checks the block of memory at src, for up to size
-// bytes, and throws if it finds a Go pointer.  The gcbits mark each
-// pointer value.  The src pointer is off bytes into the gcbits.
+// bytes, and throws if it finds a Go pointer. The gcbits mark each
+// pointer value. The src pointer is off bytes into the gcbits.
 //go:nosplit
 //go:nowritebarrier
 func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
@@ -184,15 +192,24 @@ func cgoCheckBits(src unsafe.Pointer, gcbits *byte, off, size uintptr) {
 
 // cgoCheckUsingType is like cgoCheckTypedBlock, but is a last ditch
 // fall back to look for pointers in src using the type information.
-// We only this when looking at a value on the stack when the type
+// We only use this when looking at a value on the stack when the type
 // uses a GC program, because otherwise it's more efficient to use the
-// GC bits.  This is called on the system stack.
+// GC bits. This is called on the system stack.
 //go:nowritebarrier
 //go:systemstack
 func cgoCheckUsingType(typ *_type, src unsafe.Pointer, off, size uintptr) {
 	if typ.kind&kindNoPointers != 0 {
 		return
 	}
+
+	// Anything past typ.ptrdata is not a pointer.
+	if typ.ptrdata <= off {
+		return
+	}
+	if ptrdataSize := typ.ptrdata - off; size > ptrdataSize {
+		size = ptrdataSize
+	}
+
 	if typ.kind&kindGCProg == 0 {
 		cgoCheckBits(src, typ.gcdata, off, size)
 		return
diff --git a/libgo/go/runtime/chan_test.go b/libgo/go/runtime/chan_test.go
index 6553509457d..4bd061dbc7b 100644
--- a/libgo/go/runtime/chan_test.go
+++ b/libgo/go/runtime/chan_test.go
@@ -578,7 +578,7 @@ func TestSelectDuplicateChannel(t *testing.T) {
 		}
 		e <- 9
 	}()
-	time.Sleep(time.Millisecond) // make sure goroutine A gets qeueued first on c
+	time.Sleep(time.Millisecond) // make sure goroutine A gets queued first on c
 
 	// goroutine B
 	go func() {
@@ -591,6 +591,84 @@ func TestSelectDuplicateChannel(t *testing.T) {
 	c <- 8 // wake up B.  This operation used to fail because c.recvq was corrupted (it tries to wake up an already running G instead of B)
 }
 
+var selectSink interface{}
+
+func TestSelectStackAdjust(t *testing.T) {
+	// Test that channel receive slots that contain local stack
+	// pointers are adjusted correctly by stack shrinking.
+	c := make(chan *int)
+	d := make(chan *int)
+	ready1 := make(chan bool)
+	ready2 := make(chan bool)
+
+	f := func(ready chan bool, dup bool) {
+		// Temporarily grow the stack to 10K.
+		stackGrowthRecursive((10 << 10) / (128 * 8))
+
+		// We're ready to trigger GC and stack shrink.
+		ready <- true
+
+		val := 42
+		var cx *int
+		cx = &val
+
+		var c2 chan *int
+		var d2 chan *int
+		if dup {
+			c2 = c
+			d2 = d
+		}
+
+		// Receive from d. cx won't be affected.
+		select {
+		case cx = <-c:
+		case <-c2:
+		case <-d:
+		case <-d2:
+		}
+
+		// Check that pointer in cx was adjusted correctly.
+		if cx != &val {
+			t.Error("cx no longer points to val")
+		} else if val != 42 {
+			t.Error("val changed")
+		} else {
+			*cx = 43
+			if val != 43 {
+				t.Error("changing *cx failed to change val")
+			}
+		}
+		ready <- true
+	}
+
+	go f(ready1, false)
+	go f(ready2, true)
+
+	// Let the goroutines get into the select.
+	<-ready1
+	<-ready2
+	time.Sleep(10 * time.Millisecond)
+
+	// Force concurrent GC a few times.
+	var before, after runtime.MemStats
+	runtime.ReadMemStats(&before)
+	for i := 0; i < 100; i++ {
+		selectSink = new([1 << 20]byte)
+		runtime.ReadMemStats(&after)
+		if after.NumGC-before.NumGC >= 2 {
+			goto done
+		}
+	}
+	t.Fatal("failed to trigger concurrent GC")
+done:
+	selectSink = nil
+
+	// Wake selects.
+	close(d)
+	<-ready1
+	<-ready2
+}
+
 func BenchmarkChanNonblocking(b *testing.B) {
 	myc := make(chan int)
 	b.RunParallel(func(pb *testing.PB) {
@@ -721,7 +799,7 @@ func BenchmarkChanContended(b *testing.B) {
 	})
 }
 
-func BenchmarkChanSync(b *testing.B) {
+func benchmarkChanSync(b *testing.B, work int) {
 	const CallsPerSched = 1000
 	procs := 2
 	N := int32(b.N / CallsPerSched / procs * procs)
@@ -737,10 +815,14 @@ func BenchmarkChanSync(b *testing.B) {
 				for g := 0; g < CallsPerSched; g++ {
 					if i%2 == 0 {
 						<-myc
+						localWork(work)
 						myc <- 0
+						localWork(work)
 					} else {
 						myc <- 0
+						localWork(work)
 						<-myc
+						localWork(work)
 					}
 				}
 			}
@@ -752,6 +834,14 @@ func BenchmarkChanSync(b *testing.B) {
 	}
 }
 
+func BenchmarkChanSync(b *testing.B) {
+	benchmarkChanSync(b, 0)
+}
+
+func BenchmarkChanSyncWork(b *testing.B) {
+	benchmarkChanSync(b, 1000)
+}
+
 func benchmarkChanProdCons(b *testing.B, chanSize, localWork int) {
 	const CallsPerSched = 1000
 	procs := runtime.GOMAXPROCS(-1)
@@ -925,3 +1015,18 @@ func BenchmarkChanPopular(b *testing.B) {
 	}
 	wg.Wait()
 }
+
+var (
+	alwaysFalse = false
+	workSink    = 0
+)
+
+func localWork(w int) {
+	foo := 0
+	for i := 0; i < w; i++ {
+		foo /= (foo + 1)
+	}
+	if alwaysFalse {
+		workSink += foo
+	}
+}
diff --git a/libgo/go/runtime/chanbarrier_test.go b/libgo/go/runtime/chanbarrier_test.go
index 770b850f874..b6029fb0445 100644
--- a/libgo/go/runtime/chanbarrier_test.go
+++ b/libgo/go/runtime/chanbarrier_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/compiler.go b/libgo/go/runtime/compiler.go
index b04be6181a7..02787ec5580 100644
--- a/libgo/go/runtime/compiler.go
+++ b/libgo/go/runtime/compiler.go
@@ -1,11 +1,11 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package runtime
 
 // Compiler is the name of the compiler toolchain that built the
-// running binary.  Known toolchains are:
+// running binary. Known toolchains are:
 //
 //	gc      Also known as cmd/compile.
 //	gccgo   The gccgo front end, part of the GCC compiler suite.
diff --git a/libgo/go/runtime/crash_cgo_test.go b/libgo/go/runtime/crash_cgo_test.go
index d7b367f941f..2504bd0f415 100644
--- a/libgo/go/runtime/crash_cgo_test.go
+++ b/libgo/go/runtime/crash_cgo_test.go
@@ -7,10 +7,15 @@
 package runtime_test
 
 import (
+	"bytes"
+	"fmt"
+	"internal/testenv"
+	"os"
 	"os/exec"
 	"runtime"
 	"strings"
 	"testing"
+	"time"
 )
 
 func TestCgoCrashHandler(t *testing.T) {
@@ -46,6 +51,8 @@ func TestCgoCallbackGC(t *testing.T) {
 			t.Skip("see golang.org/issue/11990")
 		case runtime.GOOS == "linux" && runtime.GOARCH == "arm":
 			t.Skip("too slow for arm builders")
+		case runtime.GOOS == "linux" && (runtime.GOARCH == "mips64" || runtime.GOARCH == "mips64le"):
+			t.Skip("too slow for mips64x builders")
 		}
 	}
 	got := runTestProg(t, "testprogcgo", "CgoCallbackGC")
@@ -147,3 +154,137 @@ func TestEnsureDropM(t *testing.T) {
 		t.Errorf("expected %q, got %v", want, got)
 	}
 }
+
+// Test for issue 14387.
+// Test that the program that doesn't need any cgo pointer checking
+// takes about the same amount of time with it as without it.
+func TestCgoCheckBytes(t *testing.T) {
+	// Make sure we don't count the build time as part of the run time.
+	testenv.MustHaveGoBuild(t)
+	exe, err := buildTestProg(t, "testprogcgo")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Try it 10 times to avoid flakiness.
+	const tries = 10
+	var tot1, tot2 time.Duration
+	for i := 0; i < tries; i++ {
+		cmd := testEnv(exec.Command(exe, "CgoCheckBytes"))
+		cmd.Env = append(cmd.Env, "GODEBUG=cgocheck=0", fmt.Sprintf("GO_CGOCHECKBYTES_TRY=%d", i))
+
+		start := time.Now()
+		cmd.Run()
+		d1 := time.Since(start)
+
+		cmd = testEnv(exec.Command(exe, "CgoCheckBytes"))
+		cmd.Env = append(cmd.Env, fmt.Sprintf("GO_CGOCHECKBYTES_TRY=%d", i))
+
+		start = time.Now()
+		cmd.Run()
+		d2 := time.Since(start)
+
+		if d1*20 > d2 {
+			// The slow version (d2) was less than 20 times
+			// slower than the fast version (d1), so OK.
+			return
+		}
+
+		tot1 += d1
+		tot2 += d2
+	}
+
+	t.Errorf("cgo check too slow: got %v, expected at most %v", tot2/tries, (tot1/tries)*20)
+}
+
+func TestCgoPanicDeadlock(t *testing.T) {
+	// test issue 14432
+	got := runTestProg(t, "testprogcgo", "CgoPanicDeadlock")
+	want := "panic: cgo error\n\n"
+	if !strings.HasPrefix(got, want) {
+		t.Fatalf("output does not start with %q:\n%s", want, got)
+	}
+}
+
+func TestCgoCCodeSIGPROF(t *testing.T) {
+	got := runTestProg(t, "testprogcgo", "CgoCCodeSIGPROF")
+	want := "OK\n"
+	if got != want {
+		t.Errorf("expected %q got %v", want, got)
+	}
+}
+
+func TestCgoCrashTraceback(t *testing.T) {
+	if runtime.GOOS != "linux" || runtime.GOARCH != "amd64" {
+		t.Skipf("not yet supported on %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+	got := runTestProg(t, "testprogcgo", "CrashTraceback")
+	for i := 1; i <= 3; i++ {
+		if !strings.Contains(got, fmt.Sprintf("cgo symbolizer:%d", i)) {
+			t.Errorf("missing cgo symbolizer:%d", i)
+		}
+	}
+}
+
+func TestCgoTracebackContext(t *testing.T) {
+	got := runTestProg(t, "testprogcgo", "TracebackContext")
+	want := "OK\n"
+	if got != want {
+		t.Errorf("expected %q got %v", want, got)
+	}
+}
+
+func testCgoPprof(t *testing.T, buildArg, runArg string) {
+	if runtime.GOOS != "linux" || runtime.GOARCH != "amd64" {
+		t.Skipf("not yet supported on %s/%s", runtime.GOOS, runtime.GOARCH)
+	}
+	testenv.MustHaveGoRun(t)
+
+	exe, err := buildTestProg(t, "testprogcgo", buildArg)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := testEnv(exec.Command(exe, runArg)).CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+	fn := strings.TrimSpace(string(got))
+	defer os.Remove(fn)
+
+	cmd := testEnv(exec.Command("go", "tool", "pprof", "-top", "-nodecount=1", exe, fn))
+
+	found := false
+	for i, e := range cmd.Env {
+		if strings.HasPrefix(e, "PPROF_TMPDIR=") {
+			cmd.Env[i] = "PPROF_TMPDIR=" + os.TempDir()
+			found = true
+			break
+		}
+	}
+	if !found {
+		cmd.Env = append(cmd.Env, "PPROF_TMPDIR="+os.TempDir())
+	}
+
+	top, err := cmd.CombinedOutput()
+	t.Logf("%s", top)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Contains(top, []byte("cpuHog")) {
+		t.Error("missing cpuHog in pprof output")
+	}
+}
+
+func TestCgoPprof(t *testing.T) {
+	testCgoPprof(t, "", "CgoPprof")
+}
+
+func TestCgoPprofPIE(t *testing.T) {
+	testCgoPprof(t, "-ldflags=-extldflags=-pie", "CgoPprof")
+}
+
+func TestCgoPprofThread(t *testing.T) {
+	testCgoPprof(t, "", "CgoPprofThread")
+}
diff --git a/libgo/go/runtime/crash_nonunix_test.go b/libgo/go/runtime/crash_nonunix_test.go
new file mode 100644
index 00000000000..2ce995c0691
--- /dev/null
+++ b/libgo/go/runtime/crash_nonunix_test.go
@@ -0,0 +1,13 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows plan9 nacl
+
+package runtime_test
+
+import "os"
+
+// sigquit is the signal to send to kill a hanging testdata program.
+// On Unix we send SIGQUIT, but on non-Unix we only have os.Kill.
+var sigquit = os.Kill
diff --git a/libgo/go/runtime/crash_test.go b/libgo/go/runtime/crash_test.go
index 5f0e77b0dc3..a2f7ff7dec8 100644
--- a/libgo/go/runtime/crash_test.go
+++ b/libgo/go/runtime/crash_test.go
@@ -5,6 +5,7 @@
 package runtime_test
 
 import (
+	"bytes"
 	"fmt"
 	"internal/testenv"
 	"io/ioutil"
@@ -13,9 +14,11 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strconv"
 	"strings"
 	"sync"
 	"testing"
+	"time"
 )
 
 var toRemove []string
@@ -65,11 +68,48 @@ func runTestProg(t *testing.T, binary, name string) string {
 	if err != nil {
 		t.Fatal(err)
 	}
-	got, _ := testEnv(exec.Command(exe, name)).CombinedOutput()
-	return string(got)
+
+	cmd := testEnv(exec.Command(exe, name))
+	var b bytes.Buffer
+	cmd.Stdout = &b
+	cmd.Stderr = &b
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("starting %s %s: %v", binary, name, err)
+	}
+
+	// If the process doesn't complete within 1 minute,
+	// assume it is hanging and kill it to get a stack trace.
+	p := cmd.Process
+	done := make(chan bool)
+	go func() {
+		scale := 1
+		// This GOARCH/GOOS test is copied from cmd/dist/test.go.
+		// TODO(iant): Have cmd/dist update the environment variable.
+		if runtime.GOARCH == "arm" || runtime.GOOS == "windows" {
+			scale = 2
+		}
+		if s := os.Getenv("GO_TEST_TIMEOUT_SCALE"); s != "" {
+			if sc, err := strconv.Atoi(s); err == nil {
+				scale = sc
+			}
+		}
+
+		select {
+		case <-done:
+		case <-time.After(time.Duration(scale) * time.Minute):
+			p.Signal(sigquit)
+		}
+	}()
+
+	if err := cmd.Wait(); err != nil {
+		t.Logf("%s %s exit status: %v", binary, name, err)
+	}
+	close(done)
+
+	return b.String()
 }
 
-func buildTestProg(t *testing.T, binary string) (string, error) {
+func buildTestProg(t *testing.T, binary string, flags ...string) (string, error) {
 	checkStaleRuntime(t)
 
 	testprog.Lock()
@@ -86,23 +126,27 @@ func buildTestProg(t *testing.T, binary string) (string, error) {
 	if testprog.target == nil {
 		testprog.target = make(map[string]buildexe)
 	}
-	target, ok := testprog.target[binary]
+	name := binary
+	if len(flags) > 0 {
+		name += "_" + strings.Join(flags, "_")
+	}
+	target, ok := testprog.target[name]
 	if ok {
 		return target.exe, target.err
 	}
 
-	exe := filepath.Join(testprog.dir, binary+".exe")
-	cmd := exec.Command("go", "build", "-o", exe)
+	exe := filepath.Join(testprog.dir, name+".exe")
+	cmd := exec.Command("go", append([]string{"build", "-o", exe}, flags...)...)
 	cmd.Dir = "testdata/" + binary
 	out, err := testEnv(cmd).CombinedOutput()
 	if err != nil {
 		exe = ""
-		target.err = fmt.Errorf("building %s: %v\n%s", binary, err, out)
-		testprog.target[binary] = target
+		target.err = fmt.Errorf("building %s %v: %v\n%s", binary, flags, err, out)
+		testprog.target[name] = target
 		return "", target.err
 	}
 	target.exe = exe
-	testprog.target[binary] = target
+	testprog.target[name] = target
 	return exe, nil
 }
 
@@ -273,6 +317,52 @@ func TestGoexitInPanic(t *testing.T) {
 	}
 }
 
+// Issue 14965: Runtime panics should be of type runtime.Error
+func TestRuntimePanicWithRuntimeError(t *testing.T) {
+	testCases := [...]func(){
+		0: func() {
+			var m map[uint64]bool
+			m[1234] = true
+		},
+		1: func() {
+			ch := make(chan struct{})
+			close(ch)
+			close(ch)
+		},
+		2: func() {
+			var ch = make(chan struct{})
+			close(ch)
+			ch <- struct{}{}
+		},
+		3: func() {
+			var s = make([]int, 2)
+			_ = s[2]
+		},
+		4: func() {
+			n := -1
+			_ = make(chan bool, n)
+		},
+		5: func() {
+			close((chan bool)(nil))
+		},
+	}
+
+	for i, fn := range testCases {
+		got := panicValue(fn)
+		if _, ok := got.(runtime.Error); !ok {
+			t.Errorf("test #%d: recovered value %v(type %T) does not implement runtime.Error", i, got, got)
+		}
+	}
+}
+
+func panicValue(fn func()) (recovered interface{}) {
+	defer func() {
+		recovered = recover()
+	}()
+	fn()
+	return
+}
+
 func TestPanicAfterGoexit(t *testing.T) {
 	// an uncaught panic should still work after goexit
 	output := runTestProg(t, "testprog", "PanicAfterGoexit")
@@ -294,9 +384,9 @@ func TestRecoverBeforePanicAfterGoexit(t *testing.T) {
 	// 1. defer a function that recovers
 	// 2. defer a function that panics
 	// 3. call goexit
-	// Goexit should run the #2 defer.  Its panic
+	// Goexit should run the #2 defer. Its panic
 	// should be caught by the #1 defer, and execution
-	// should resume in the caller.  Like the Goexit
+	// should resume in the caller. Like the Goexit
 	// never happened!
 	defer func() {
 		r := recover()
@@ -336,3 +426,59 @@ func TestPanicTraceback(t *testing.T) {
 		output = output[idx[1]:]
 	}
 }
+
+func testPanicDeadlock(t *testing.T, name string, want string) {
+	// test issue 14432
+	output := runTestProg(t, "testprog", name)
+	if !strings.HasPrefix(output, want) {
+		t.Fatalf("output does not start with %q:\n%s", want, output)
+	}
+}
+
+func TestPanicDeadlockGosched(t *testing.T) {
+	testPanicDeadlock(t, "GoschedInPanic", "panic: errorThatGosched\n\n")
+}
+
+func TestPanicDeadlockSyscall(t *testing.T) {
+	testPanicDeadlock(t, "SyscallInPanic", "1\n2\npanic: 3\n\n")
+}
+
+func TestMemPprof(t *testing.T) {
+	testenv.MustHaveGoRun(t)
+
+	exe, err := buildTestProg(t, "testprog")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := testEnv(exec.Command(exe, "MemProf")).CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+	fn := strings.TrimSpace(string(got))
+	defer os.Remove(fn)
+
+	cmd := testEnv(exec.Command("go", "tool", "pprof", "-alloc_space", "-top", exe, fn))
+
+	found := false
+	for i, e := range cmd.Env {
+		if strings.HasPrefix(e, "PPROF_TMPDIR=") {
+			cmd.Env[i] = "PPROF_TMPDIR=" + os.TempDir()
+			found = true
+			break
+		}
+	}
+	if !found {
+		cmd.Env = append(cmd.Env, "PPROF_TMPDIR="+os.TempDir())
+	}
+
+	top, err := cmd.CombinedOutput()
+	t.Logf("%s", top)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Contains(top, []byte("MemProf")) {
+		t.Error("missing MemProf in pprof output")
+	}
+}
diff --git a/libgo/go/runtime/crash_unix_test.go b/libgo/go/runtime/crash_unix_test.go
index 771b303f6ee..6e4d04bd200 100644
--- a/libgo/go/runtime/crash_unix_test.go
+++ b/libgo/go/runtime/crash_unix_test.go
@@ -19,6 +19,10 @@ import (
 	"testing"
 )
 
+// sigquit is the signal to send to kill a hanging testdata program.
+// Send SIGQUIT to get a stack trace.
+var sigquit = syscall.SIGQUIT
+
 func TestCrashDumpsAllThreads(t *testing.T) {
 	switch runtime.GOOS {
 	case "darwin", "dragonfly", "freebsd", "linux", "netbsd", "openbsd", "solaris":
@@ -149,10 +153,6 @@ func loop(i int, c chan bool) {
 
 func TestSignalExitStatus(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
-	switch runtime.GOOS {
-	case "netbsd", "solaris":
-		t.Skipf("skipping on %s; see https://golang.org/issue/14063", runtime.GOOS)
-	}
 	exe, err := buildTestProg(t, "testprog")
 	if err != nil {
 		t.Fatal(err)
diff --git a/libgo/go/runtime/debug.go b/libgo/go/runtime/debug.go
index 0c915a2a768..56d19d7a4cf 100644
--- a/libgo/go/runtime/debug.go
+++ b/libgo/go/runtime/debug.go
@@ -17,7 +17,7 @@ func LockOSThread()
 func UnlockOSThread()
 
 // GOMAXPROCS sets the maximum number of CPUs that can be executing
-// simultaneously and returns the previous setting.  If n < 1, it does not
+// simultaneously and returns the previous setting. If n < 1, it does not
 // change the current setting.
 // The number of logical CPUs on the local machine can be queried with NumCPU.
 // This call will go away when the scheduler improves.
diff --git a/libgo/go/runtime/debug/garbage.go b/libgo/go/runtime/debug/garbage.go
index 0f8a44c4c63..8d52837a44a 100644
--- a/libgo/go/runtime/debug/garbage.go
+++ b/libgo/go/runtime/debug/garbage.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -149,7 +149,13 @@ func SetPanicOnFault(enabled bool) bool
 
 // WriteHeapDump writes a description of the heap and the objects in
 // it to the given file descriptor.
-// The heap dump format is defined at https://golang.org/s/go13heapdump.
+//
+// WriteHeapDump suspends the execution of all goroutines until the heap
+// dump is completely written.  Thus, the file descriptor must not be
+// connected to a pipe or socket whose other end is in the same Go
+// process; instead, use a temporary file or network socket.
+//
+// The heap dump format is defined at https://golang.org/s/go15heapdump.
 func WriteHeapDump(fd uintptr)
 
 // SetTraceback sets the amount of detail printed by the runtime in
diff --git a/libgo/go/runtime/debug/garbage_test.go b/libgo/go/runtime/debug/garbage_test.go
index 21bf6eb5582..3d07cbbe45f 100644
--- a/libgo/go/runtime/debug/garbage_test.go
+++ b/libgo/go/runtime/debug/garbage_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/debug/heapdump_test.go b/libgo/go/runtime/debug/heapdump_test.go
index 5761c015b8e..7d5b950895d 100644
--- a/libgo/go/runtime/debug/heapdump_test.go
+++ b/libgo/go/runtime/debug/heapdump_test.go
@@ -38,7 +38,7 @@ type Obj struct {
 }
 
 func objfin(x *Obj) {
-	println("finalized", x)
+	//println("finalized", x)
 }
 
 func TestWriteHeapDumpFinalizers(t *testing.T) {
diff --git a/libgo/go/runtime/debug/stack_test.go b/libgo/go/runtime/debug/stack_test.go
index 0f769ee6cab..5f9f60c94f3 100644
--- a/libgo/go/runtime/debug/stack_test.go
+++ b/libgo/go/runtime/debug/stack_test.go
@@ -57,7 +57,7 @@ func TestStack(t *testing.T) {
 }
 
 func check(t *testing.T, line, has string) {
-	if strings.Index(line, has) < 0 {
+	if !strings.Contains(line, has) {
 		t.Errorf("expected %q in %q", has, line)
 	}
 }
diff --git a/libgo/go/runtime/defs_linux_s390x.go b/libgo/go/runtime/defs_linux_s390x.go
new file mode 100644
index 00000000000..5f55d5a8894
--- /dev/null
+++ b/libgo/go/runtime/defs_linux_s390x.go
@@ -0,0 +1,167 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+const (
+	_EINTR  = 0x4
+	_EAGAIN = 0xb
+	_ENOMEM = 0xc
+
+	_PROT_NONE  = 0x0
+	_PROT_READ  = 0x1
+	_PROT_WRITE = 0x2
+	_PROT_EXEC  = 0x4
+
+	_MAP_ANON    = 0x20
+	_MAP_PRIVATE = 0x2
+	_MAP_FIXED   = 0x10
+
+	_MADV_DONTNEED   = 0x4
+	_MADV_HUGEPAGE   = 0xe
+	_MADV_NOHUGEPAGE = 0xf
+
+	_SA_RESTART = 0x10000000
+	_SA_ONSTACK = 0x8000000
+	_SA_SIGINFO = 0x4
+
+	_SIGHUP    = 0x1
+	_SIGINT    = 0x2
+	_SIGQUIT   = 0x3
+	_SIGILL    = 0x4
+	_SIGTRAP   = 0x5
+	_SIGABRT   = 0x6
+	_SIGBUS    = 0x7
+	_SIGFPE    = 0x8
+	_SIGKILL   = 0x9
+	_SIGUSR1   = 0xa
+	_SIGSEGV   = 0xb
+	_SIGUSR2   = 0xc
+	_SIGPIPE   = 0xd
+	_SIGALRM   = 0xe
+	_SIGSTKFLT = 0x10
+	_SIGCHLD   = 0x11
+	_SIGCONT   = 0x12
+	_SIGSTOP   = 0x13
+	_SIGTSTP   = 0x14
+	_SIGTTIN   = 0x15
+	_SIGTTOU   = 0x16
+	_SIGURG    = 0x17
+	_SIGXCPU   = 0x18
+	_SIGXFSZ   = 0x19
+	_SIGVTALRM = 0x1a
+	_SIGPROF   = 0x1b
+	_SIGWINCH  = 0x1c
+	_SIGIO     = 0x1d
+	_SIGPWR    = 0x1e
+	_SIGSYS    = 0x1f
+
+	_FPE_INTDIV = 0x1
+	_FPE_INTOVF = 0x2
+	_FPE_FLTDIV = 0x3
+	_FPE_FLTOVF = 0x4
+	_FPE_FLTUND = 0x5
+	_FPE_FLTRES = 0x6
+	_FPE_FLTINV = 0x7
+	_FPE_FLTSUB = 0x8
+
+	_BUS_ADRALN = 0x1
+	_BUS_ADRERR = 0x2
+	_BUS_OBJERR = 0x3
+
+	_SEGV_MAPERR = 0x1
+	_SEGV_ACCERR = 0x2
+
+	_ITIMER_REAL    = 0x0
+	_ITIMER_VIRTUAL = 0x1
+	_ITIMER_PROF    = 0x2
+
+	_EPOLLIN       = 0x1
+	_EPOLLOUT      = 0x4
+	_EPOLLERR      = 0x8
+	_EPOLLHUP      = 0x10
+	_EPOLLRDHUP    = 0x2000
+	_EPOLLET       = 0x80000000
+	_EPOLL_CLOEXEC = 0x80000
+	_EPOLL_CTL_ADD = 0x1
+	_EPOLL_CTL_DEL = 0x2
+	_EPOLL_CTL_MOD = 0x3
+)
+
+type timespec struct {
+	tv_sec  int64
+	tv_nsec int64
+}
+
+func (ts *timespec) set_sec(x int64) {
+	ts.tv_sec = x
+}
+
+func (ts *timespec) set_nsec(x int32) {
+	ts.tv_nsec = int64(x)
+}
+
+type timeval struct {
+	tv_sec  int64
+	tv_usec int64
+}
+
+func (tv *timeval) set_usec(x int32) {
+	tv.tv_usec = int64(x)
+}
+
+type sigactiont struct {
+	sa_handler  uintptr
+	sa_flags    uint64
+	sa_restorer uintptr
+	sa_mask     uint64
+}
+
+type siginfo struct {
+	si_signo int32
+	si_errno int32
+	si_code  int32
+	// below here is a union; si_addr is the only field we use
+	si_addr uint64
+}
+
+type itimerval struct {
+	it_interval timeval
+	it_value    timeval
+}
+
+type epollevent struct {
+	events    uint32
+	pad_cgo_0 [4]byte
+	data      [8]byte // unaligned uintptr
+}
+
+const (
+	_O_RDONLY    = 0x0
+	_O_CLOEXEC   = 0x80000
+	_SA_RESTORER = 0
+)
+
+type sigaltstackt struct {
+	ss_sp    *byte
+	ss_flags int32
+	ss_size  uintptr
+}
+
+type sigcontext struct {
+	psw_mask uint64
+	psw_addr uint64
+	gregs    [16]uint64
+	aregs    [16]uint32
+	fpc      uint32
+	fpregs   [16]uint64
+}
+
+type ucontext struct {
+	uc_flags    uint64
+	uc_link     *ucontext
+	uc_stack    sigaltstackt
+	uc_mcontext sigcontext
+	uc_sigmask  uint64
+}
diff --git a/libgo/go/runtime/defs_plan9_arm.go b/libgo/go/runtime/defs_plan9_arm.go
new file mode 100644
index 00000000000..9c700ae1c0b
--- /dev/null
+++ b/libgo/go/runtime/defs_plan9_arm.go
@@ -0,0 +1,63 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+const _PAGESIZE = 0x1000
+
+type ureg struct {
+	r0   uint32 /* general registers */
+	r1   uint32 /* ... */
+	r2   uint32 /* ... */
+	r3   uint32 /* ... */
+	r4   uint32 /* ... */
+	r5   uint32 /* ... */
+	r6   uint32 /* ... */
+	r7   uint32 /* ... */
+	r8   uint32 /* ... */
+	r9   uint32 /* ... */
+	r10  uint32 /* ... */
+	r11  uint32 /* ... */
+	r12  uint32 /* ... */
+	sp   uint32
+	link uint32 /* ... */
+	trap uint32 /* trap type */
+	psr  uint32
+	pc   uint32 /* interrupted addr */
+}
+
+type sigctxt struct {
+	u *ureg
+}
+
+func (c *sigctxt) pc() uintptr { return uintptr(c.u.pc) }
+func (c *sigctxt) sp() uintptr { return uintptr(c.u.sp) }
+func (c *sigctxt) lr() uintptr { return uintptr(c.u.link) }
+
+func (c *sigctxt) setpc(x uintptr)  { c.u.pc = uint32(x) }
+func (c *sigctxt) setsp(x uintptr)  { c.u.sp = uint32(x) }
+func (c *sigctxt) setlr(x uintptr)  { c.u.link = uint32(x) }
+func (c *sigctxt) savelr(x uintptr) { c.u.r0 = uint32(x) }
+
+func dumpregs(u *ureg) {
+	print("r0    ", hex(u.r0), "\n")
+	print("r1    ", hex(u.r1), "\n")
+	print("r2    ", hex(u.r2), "\n")
+	print("r3    ", hex(u.r3), "\n")
+	print("r4    ", hex(u.r4), "\n")
+	print("r5    ", hex(u.r5), "\n")
+	print("r6    ", hex(u.r6), "\n")
+	print("r7    ", hex(u.r7), "\n")
+	print("r8    ", hex(u.r8), "\n")
+	print("r9    ", hex(u.r9), "\n")
+	print("r10   ", hex(u.r10), "\n")
+	print("r11   ", hex(u.r11), "\n")
+	print("r12   ", hex(u.r12), "\n")
+	print("sp    ", hex(u.sp), "\n")
+	print("link  ", hex(u.link), "\n")
+	print("pc    ", hex(u.pc), "\n")
+	print("psr   ", hex(u.psr), "\n")
+}
+
+func sigpanictramp()
diff --git a/libgo/go/runtime/error.go b/libgo/go/runtime/error.go
index c4621b6f858..b9c73655255 100644
--- a/libgo/go/runtime/error.go
+++ b/libgo/go/runtime/error.go
@@ -101,11 +101,6 @@ func (e errorString) Error() string {
 	return "runtime error: " + string(e)
 }
 
-// For calling from C.
-func NewErrorString(s string, ret *interface{}) {
-	*ret = errorString(s)
-}
-
 // An errorCString represents a runtime error described by a single C string.
 // Not "type errorCString uintptr" because of http://golang.org/issue/7084.
 type errorCString struct{ cstr uintptr }
@@ -123,6 +118,17 @@ func NewErrorCString(s uintptr, ret *interface{}) {
 	*ret = errorCString{s}
 }
 
+// plainError represents a runtime error described a string without
+// the prefix "runtime error: " after invoking errorString.Error().
+// See Issue #14965.
+type plainError string
+
+func (e plainError) RuntimeError() {}
+
+func (e plainError) Error() string {
+	return string(e)
+}
+
 type stringer interface {
 	String() string
 }
@@ -152,5 +158,5 @@ func Printany(i interface{}) {
 
 // called from generated code
 func panicwrap(pkg, typ, meth string) {
-	panic("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer")
+	panic(plainError("value method " + pkg + "." + typ + "." + meth + " called using nil *" + typ + " pointer"))
 }
diff --git a/libgo/go/runtime/export_arm_test.go b/libgo/go/runtime/export_arm_test.go
index 446d26465c8..b8a89fc0d22 100644
--- a/libgo/go/runtime/export_arm_test.go
+++ b/libgo/go/runtime/export_arm_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/export_linux_test.go b/libgo/go/runtime/export_linux_test.go
index 4e76600e207..183a6eeee2a 100644
--- a/libgo/go/runtime/export_linux_test.go
+++ b/libgo/go/runtime/export_linux_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/export_mmap_test.go b/libgo/go/runtime/export_mmap_test.go
index 07b0a56e09e..7bde44dc430 100644
--- a/libgo/go/runtime/export_mmap_test.go
+++ b/libgo/go/runtime/export_mmap_test.go
@@ -1,4 +1,4 @@
-// Copyright 2016 The Go Authors.  All rights reserved.
+// Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/export_test.go b/libgo/go/runtime/export_test.go
index fd328a1d363..7ba217eb782 100644
--- a/libgo/go/runtime/export_test.go
+++ b/libgo/go/runtime/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -117,6 +117,113 @@ func Close(fd int32) int32 {
 	return close(fd)
 }
 
+/*
+func RunSchedLocalQueueTest() {
+	_p_ := new(p)
+	gs := make([]g, len(_p_.runq))
+	for i := 0; i < len(_p_.runq); i++ {
+		if g, _ := runqget(_p_); g != nil {
+			throw("runq is not empty initially")
+		}
+		for j := 0; j < i; j++ {
+			runqput(_p_, &gs[i], false)
+		}
+		for j := 0; j < i; j++ {
+			if g, _ := runqget(_p_); g != &gs[i] {
+				print("bad element at iter ", i, "/", j, "\n")
+				throw("bad element")
+			}
+		}
+		if g, _ := runqget(_p_); g != nil {
+			throw("runq is not empty afterwards")
+		}
+	}
+}
+
+func RunSchedLocalQueueStealTest() {
+	p1 := new(p)
+	p2 := new(p)
+	gs := make([]g, len(p1.runq))
+	for i := 0; i < len(p1.runq); i++ {
+		for j := 0; j < i; j++ {
+			gs[j].sig = 0
+			runqput(p1, &gs[j], false)
+		}
+		gp := runqsteal(p2, p1, true)
+		s := 0
+		if gp != nil {
+			s++
+			gp.sig++
+		}
+		for {
+			gp, _ = runqget(p2)
+			if gp == nil {
+				break
+			}
+			s++
+			gp.sig++
+		}
+		for {
+			gp, _ = runqget(p1)
+			if gp == nil {
+				break
+			}
+			gp.sig++
+		}
+		for j := 0; j < i; j++ {
+			if gs[j].sig != 1 {
+				print("bad element ", j, "(", gs[j].sig, ") at iter ", i, "\n")
+				throw("bad element")
+			}
+		}
+		if s != i/2 && s != i/2+1 {
+			print("bad steal ", s, ", want ", i/2, " or ", i/2+1, ", iter ", i, "\n")
+			throw("bad steal")
+		}
+	}
+}
+
+func RunSchedLocalQueueEmptyTest(iters int) {
+	// Test that runq is not spuriously reported as empty.
+	// Runq emptiness affects scheduling decisions and spurious emptiness
+	// can lead to underutilization (both runnable Gs and idle Ps coexist
+	// for arbitrary long time).
+	done := make(chan bool, 1)
+	p := new(p)
+	gs := make([]g, 2)
+	ready := new(uint32)
+	for i := 0; i < iters; i++ {
+		*ready = 0
+		next0 := (i & 1) == 0
+		next1 := (i & 2) == 0
+		runqput(p, &gs[0], next0)
+		go func() {
+			for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
+			}
+			if runqempty(p) {
+				println("next:", next0, next1)
+				throw("queue is empty")
+			}
+			done <- true
+		}()
+		for atomic.Xadd(ready, 1); atomic.Load(ready) != 2; {
+		}
+		runqput(p, &gs[1], next1)
+		runqget(p)
+		<-done
+		runqget(p)
+	}
+}
+
+var StringHash = stringHash
+var BytesHash = bytesHash
+var Int32Hash = int32Hash
+var Int64Hash = int64Hash
+var EfaceHash = efaceHash
+var IfaceHash = ifaceHash
+var MemclrBytes = memclrBytes
+*/
+
 //extern read
 func read(fd int32, buf unsafe.Pointer, size int32) int32
 
@@ -181,3 +288,24 @@ var ForceGCPeriod = &forcegcperiod
 // the "environment" traceback level, so later calls to
 // debug.SetTraceback (e.g., from testing timeouts) can't lower it.
 func SetTracebackEnv(level string)
+
+/*
+var ReadUnaligned32 = readUnaligned32
+var ReadUnaligned64 = readUnaligned64
+
+func CountPagesInUse() (pagesInUse, counted uintptr) {
+	stopTheWorld("CountPagesInUse")
+
+	pagesInUse = uintptr(mheap_.pagesInUse)
+
+	for _, s := range h_allspans {
+		if s.state == mSpanInUse {
+			counted += s.npages
+		}
+	}
+
+	startTheWorld()
+
+	return
+}
+*/
diff --git a/libgo/go/runtime/export_windows_test.go b/libgo/go/runtime/export_windows_test.go
index 7b269ecccb4..536b398fd7a 100644
--- a/libgo/go/runtime/export_windows_test.go
+++ b/libgo/go/runtime/export_windows_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,7 +8,11 @@ package runtime
 
 import "unsafe"
 
-var TestingWER = &testingWER
+var (
+	TestingWER              = &testingWER
+	OsYield                 = osyield
+	TimeBeginPeriodRetValue = &timeBeginPeriodRetValue
+)
 
 func NumberOfProcessors() int32 {
 	var info systeminfo
diff --git a/libgo/go/runtime/extern.go b/libgo/go/runtime/extern.go
index eca54a75145..fbbf56ced70 100644
--- a/libgo/go/runtime/extern.go
+++ b/libgo/go/runtime/extern.go
@@ -82,6 +82,21 @@ It is a comma-separated list of name=val pairs setting these named variables:
 	If the line ends with "(forced)", this GC was forced by a
 	runtime.GC() call and all phases are STW.
 
+	Setting gctrace to any value > 0 also causes the garbage collector
+	to emit a summary when memory is released back to the system.
+	This process of returning memory to the system is called scavenging.
+	The format of this summary is subject to change.
+	Currently it is:
+		scvg#: # MB released  printed only if non-zero
+		scvg#: inuse: # idle: # sys: # released: # consumed: # (MB)
+	where the fields are as follows:
+		scvg#        the scavenge cycle number, incremented at each scavenge
+		inuse: #     MB used or partially used spans
+		idle: #      MB spans pending scavenging
+		sys: #       MB mapped from the system
+		released: #  MB released to the system
+		consumed: #  MB allocated from the system
+
 	memprofilerate: setting memprofilerate=X will update the value of runtime.MemProfileRate.
 	When set to 0 memory profiling is disabled.  Refer to the description of
 	MemProfileRate for the default value.
@@ -156,65 +171,34 @@ func Gosched()
 func Goexit()
 
 // Caller reports file and line number information about function invocations on
-// the calling goroutine's stack.  The argument skip is the number of stack frames
+// the calling goroutine's stack. The argument skip is the number of stack frames
 // to ascend, with 0 identifying the caller of Caller.  (For historical reasons the
 // meaning of skip differs between Caller and Callers.) The return values report the
 // program counter, file name, and line number within the file of the corresponding
 // call.  The boolean ok is false if it was not possible to recover the information.
 func Caller(skip int) (pc uintptr, file string, line int, ok bool)
 
-// Callers fills the slice pc with the program counters of function invocations
-// on the calling goroutine's stack.  The argument skip is the number of stack frames
+// Callers fills the slice pc with the return program counters of function invocations
+// on the calling goroutine's stack. The argument skip is the number of stack frames
 // to skip before recording in pc, with 0 identifying the frame for Callers itself and
 // 1 identifying the caller of Callers.
 // It returns the number of entries written to pc.
 func Callers(skip int, pc []uintptr) int
 
-type Func struct {
-	opaque struct{} // unexported field to disallow conversions
-}
-
-// FuncForPC returns a *Func describing the function that contains the
-// given program counter address, or else nil.
-func FuncForPC(pc uintptr) *Func
-
-// Name returns the name of the function.
-func (f *Func) Name() string {
-	return funcname_go(f)
-}
-
-// Entry returns the entry address of the function.
-func (f *Func) Entry() uintptr {
-	return funcentry_go(f)
-}
-
-// FileLine returns the file name and line number of the
-// source code corresponding to the program counter pc.
-// The result will not be accurate if pc is not a program
-// counter within f.
-func (f *Func) FileLine(pc uintptr) (file string, line int) {
-	return funcline_go(f, pc)
-}
-
-// implemented in symtab.c
-func funcline_go(*Func, uintptr) (string, int)
-func funcname_go(*Func) string
-func funcentry_go(*Func) uintptr
-
-// SetFinalizer sets the finalizer associated with x to f.
-// When the garbage collector finds an unreachable block
+// SetFinalizer sets the finalizer associated with obj to the provided
+// finalizer function. When the garbage collector finds an unreachable block
 // with an associated finalizer, it clears the association and runs
-// f(x) in a separate goroutine.  This makes x reachable again, but
-// now without an associated finalizer.  Assuming that SetFinalizer
+// finalizer(obj) in a separate goroutine. This makes obj reachable again,
+// but now without an associated finalizer. Assuming that SetFinalizer
 // is not called again, the next time the garbage collector sees
-// that x is unreachable, it will free x.
+// that obj is unreachable, it will free obj.
 //
-// SetFinalizer(x, nil) clears any finalizer associated with x.
+// SetFinalizer(obj, nil) clears any finalizer associated with obj.
 //
-// The argument x must be a pointer to an object allocated by
+// The argument obj must be a pointer to an object allocated by
 // calling new or by taking the address of a composite literal.
-// The argument f must be a function that takes a single argument
-// to which x's type can be assigned, and can have arbitrary ignored return
+// The argument finalizer must be a function that takes a single argument
+// to which obj's type can be assigned, and can have arbitrary ignored return
 // values. If either of these is not true, SetFinalizer aborts the
 // program.
 //
@@ -226,8 +210,8 @@ func funcentry_go(*Func) uintptr
 // is not guaranteed to run, because there is no ordering that
 // respects the dependencies.
 //
-// The finalizer for x is scheduled to run at some arbitrary time after
-// x becomes unreachable.
+// The finalizer for obj is scheduled to run at some arbitrary time after
+// obj becomes unreachable.
 // There is no guarantee that finalizers will run before a program exits,
 // so typically they are useful only for releasing non-memory resources
 // associated with an object during a long-running program.
@@ -237,13 +221,56 @@ func funcentry_go(*Func) uintptr
 // to depend on a finalizer to flush an in-memory I/O buffer such as a
 // bufio.Writer, because the buffer would not be flushed at program exit.
 //
-// It is not guaranteed that a finalizer will run if the size of *x is
+// It is not guaranteed that a finalizer will run if the size of *obj is
 // zero bytes.
 //
+// It is not guaranteed that a finalizer will run for objects allocated
+// in initializers for package-level variables. Such objects may be
+// linker-allocated, not heap-allocated.
+//
+// A finalizer may run as soon as an object becomes unreachable.
+// In order to use finalizers correctly, the program must ensure that
+// the object is reachable until it is no longer required.
+// Objects stored in global variables, or that can be found by tracing
+// pointers from a global variable, are reachable. For other objects,
+// pass the object to a call of the KeepAlive function to mark the
+// last point in the function where the object must be reachable.
+//
+// For example, if p points to a struct that contains a file descriptor d,
+// and p has a finalizer that closes that file descriptor, and if the last
+// use of p in a function is a call to syscall.Write(p.d, buf, size), then
+// p may be unreachable as soon as the program enters syscall.Write. The
+// finalizer may run at that moment, closing p.d, causing syscall.Write
+// to fail because it is writing to a closed file descriptor (or, worse,
+// to an entirely different file descriptor opened by a different goroutine).
+// To avoid this problem, call runtime.KeepAlive(p) after the call to
+// syscall.Write.
+//
 // A single goroutine runs all finalizers for a program, sequentially.
 // If a finalizer must run for a long time, it should do so by starting
 // a new goroutine.
-func SetFinalizer(x, f interface{})
+func SetFinalizer(obj interface{}, finalizer interface{})
+
+// KeepAlive marks its argument as currently reachable.
+// This ensures that the object is not freed, and its finalizer is not run,
+// before the point in the program where KeepAlive is called.
+//
+// A very simplified example showing where KeepAlive is required:
+// 	type File struct { d int }
+// 	d, err := syscall.Open("/file/path", syscall.O_RDONLY, 0)
+// 	// ... do something if err != nil ...
+// 	p := &File{d}
+// 	runtime.SetFinalizer(p, func(p *File) { syscall.Close(p.d) })
+// 	var buf [10]byte
+// 	n, err := syscall.Read(p.d, buf[:])
+// 	// Ensure p is not finalized until Read returns.
+// 	runtime.KeepAlive(p)
+// 	// No more uses of p after this point.
+//
+// Without the KeepAlive call, the finalizer could run at the start of
+// syscall.Read, closing the file descriptor before syscall.Read makes
+// the actual system call.
+func KeepAlive(interface{})
 
 func getgoroot() string
 
@@ -270,7 +297,7 @@ func Version() string {
 const GOOS string = theGoos
 
 // GOARCH is the running program's architecture target:
-// 386, amd64, arm, arm64, ppc64, ppc64le.
+// 386, amd64, arm, or s390x.
 const GOARCH string = theGoarch
 
 // GCCGOTOOLDIR is the Tool Dir for the gccgo build
diff --git a/libgo/go/runtime/fastlog2_test.go b/libgo/go/runtime/fastlog2_test.go
index 8f92dc66942..6e9fcd4d45e 100644
--- a/libgo/go/runtime/fastlog2_test.go
+++ b/libgo/go/runtime/fastlog2_test.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/gc_test.go b/libgo/go/runtime/gc_test.go
index 71d46561e03..11035c321ab 100644
--- a/libgo/go/runtime/gc_test.go
+++ b/libgo/go/runtime/gc_test.go
@@ -477,4 +477,21 @@ func testIfaceEqual(x interface{}) {
 	}
 }
 
+func TestPageAccounting(t *testing.T) {
+	// Grow the heap in small increments. This used to drop the
+	// pages-in-use count below zero because of a rounding
+	// mismatch (golang.org/issue/15022).
+	const blockSize = 64 << 10
+	blocks := make([]*[blockSize]byte, (64<<20)/blockSize)
+	for i := range blocks {
+		blocks[i] = new([blockSize]byte)
+	}
+
+	// Check that the running page count matches reality.
+	pagesInUse, counted := runtime.CountPagesInUse()
+	if pagesInUse != counted {
+		t.Fatalf("mheap_.pagesInUse is %d, but direct count is %d", pagesInUse, counted)
+	}
+}
+
 */
diff --git a/libgo/go/runtime/gcinfo_test.go b/libgo/go/runtime/gcinfo_test.go
index d3262a656c5..2253d93a0ac 100644
--- a/libgo/go/runtime/gcinfo_test.go
+++ b/libgo/go/runtime/gcinfo_test.go
@@ -45,14 +45,14 @@ func TestGCInfo(t *testing.T) {
 
 func verifyGCInfo(t *testing.T, name string, p interface{}, mask0 []byte) {
 	mask := runtime.GCMask(p)
-	if bytes.Compare(mask, mask0) != 0 {
+	if !bytes.Equal(mask, mask0) {
 		t.Errorf("bad GC program for %v:\nwant %+v\ngot  %+v", name, mask0, mask)
 		return
 	}
 }
 
 func padDead(mask []byte) []byte {
-	// Because the dead bit isn't encoded until the third word,
+	// Because the dead bit isn't encoded in the second word,
 	// and because on 32-bit systems a one-word allocation
 	// uses a two-word block, the pointer info for a one-word
 	// object needs to be expanded to include an extra scalar
@@ -67,6 +67,9 @@ func trimDead(mask []byte) []byte {
 	for len(mask) > 2 && mask[len(mask)-1] == typeScalar {
 		mask = mask[:len(mask)-1]
 	}
+	if len(mask) == 2 && mask[0] == typeScalar && mask[1] == typeScalar {
+		mask = mask[:0]
+	}
 	return mask
 }
 
@@ -130,7 +133,7 @@ func infoBigStruct() []byte {
 			typeScalar, typeScalar, typeScalar, typeScalar, // t int; y uint16; u uint64
 			typePointer, typeScalar, // i string
 		}
-	case "arm64", "amd64", "mips64", "mips64le", "ppc64", "ppc64le":
+	case "arm64", "amd64", "mips64", "mips64le", "ppc64", "ppc64le", "s390x":
 		return []byte{
 			typePointer,                        // q *int
 			typeScalar, typeScalar, typeScalar, // w byte; e [17]byte
diff --git a/libgo/go/runtime/lfstack_64bit.go b/libgo/go/runtime/lfstack_64bit.go
new file mode 100644
index 00000000000..5367f08c561
--- /dev/null
+++ b/libgo/go/runtime/lfstack_64bit.go
@@ -0,0 +1,48 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x
+
+package runtime
+
+import "unsafe"
+
+const (
+	// addrBits is the number of bits needed to represent a virtual address.
+	//
+	// In Linux the user address space for each architecture is limited as
+	// follows (taken from the processor.h file for the architecture):
+	//
+	// Architecture  Name              Maximum Value (exclusive)
+	// ---------------------------------------------------------------------
+	// arm64         TASK_SIZE_64      Depends on configuration.
+	// ppc64{,le}    TASK_SIZE_USER64  0x400000000000UL (46 bit addresses)
+	// mips64{,le}   TASK_SIZE64       0x010000000000UL (40 bit addresses)
+	// s390x         TASK_SIZE         0x020000000000UL (41 bit addresses)
+	//
+	// These values may increase over time.
+	//
+	// On AMD64, virtual addresses are 48-bit numbers sign extended to 64.
+	// We shift the address left 16 to eliminate the sign extended part and make
+	// room in the bottom for the count.
+	addrBits = 48
+
+	// In addition to the 16 bits taken from the top, we can take 3 from the
+	// bottom, because node must be pointer-aligned, giving a total of 19 bits
+	// of count.
+	cntBits = 64 - addrBits + 3
+)
+
+func lfstackPack(node *lfnode, cnt uintptr) uint64 {
+	return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
+}
+
+func lfstackUnpack(val uint64) *lfnode {
+	if GOARCH == "amd64" {
+		// amd64 systems can place the stack above the VA hole, so we need to sign extend
+		// val before unpacking.
+		return (*lfnode)(unsafe.Pointer(uintptr(int64(val) >> cntBits << 3)))
+	}
+	return (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
+}
diff --git a/libgo/go/runtime/lfstack_linux_mips64x.go b/libgo/go/runtime/lfstack_linux_mips64x.go
deleted file mode 100644
index 49b65585f42..00000000000
--- a/libgo/go/runtime/lfstack_linux_mips64x.go
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build mips64 mips64le
-// +build linux
-
-package runtime
-
-import "unsafe"
-
-// On mips64, Linux limits the user address space to 40 bits (see
-// TASK_SIZE64 in the Linux kernel).  This has grown over time,
-// so here we allow 48 bit addresses.
-//
-// In addition to the 16 bits taken from the top, we can take 3 from the
-// bottom, because node must be pointer-aligned, giving a total of 19 bits
-// of count.
-const (
-	addrBits = 48
-	cntBits  = 64 - addrBits + 3
-)
-
-func lfstackPack(node *lfnode, cnt uintptr) uint64 {
-	return uint64(uintptr(unsafe.Pointer(node)))<<(64-addrBits) | uint64(cnt&(1<<cntBits-1))
-}
-
-func lfstackUnpack(val uint64) (node *lfnode, cnt uintptr) {
-	node = (*lfnode)(unsafe.Pointer(uintptr(val >> cntBits << 3)))
-	cnt = uintptr(val & (1<<cntBits - 1))
-	return
-}
diff --git a/libgo/go/runtime/map_test.go b/libgo/go/runtime/map_test.go
index ed0347a453a..95200a47481 100644
--- a/libgo/go/runtime/map_test.go
+++ b/libgo/go/runtime/map_test.go
@@ -329,6 +329,22 @@ func TestBigItems(t *testing.T) {
 	}
 }
 
+func TestMapHugeZero(t *testing.T) {
+	type T [4000]byte
+	m := map[int]T{}
+	x := m[0]
+	if x != (T{}) {
+		t.Errorf("map value not zero")
+	}
+	y, ok := m[0]
+	if ok {
+		t.Errorf("map value should be missing")
+	}
+	if y != (T{}) {
+		t.Errorf("map value not zero")
+	}
+}
+
 type empty struct {
 }
 
diff --git a/libgo/go/runtime/mmap.go b/libgo/go/runtime/mmap.go
index a0768428b40..53617e41e4a 100644
--- a/libgo/go/runtime/mmap.go
+++ b/libgo/go/runtime/mmap.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,5 +12,8 @@ package runtime
 
 import "unsafe"
 
-// mmap calls the mmap system call.  It is implemented in assembly.
+// mmap calls the mmap system call. It is implemented in assembly.
+// We only pass the lower 32 bits of file offset to the
+// assembly routine; the higher bits (if required), should be provided
+// by the assembly routine as 0.
 func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer
diff --git a/libgo/go/runtime/msan.go b/libgo/go/runtime/msan.go
index 4dbdf05b21c..7177c8e611b 100644
--- a/libgo/go/runtime/msan.go
+++ b/libgo/go/runtime/msan.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -24,10 +24,10 @@ func MSanWrite(addr unsafe.Pointer, len int) {
 const msanenabled = true
 
 // If we are running on the system stack, the C program may have
-// marked part of that stack as uninitialized.  We don't instrument
+// marked part of that stack as uninitialized. We don't instrument
 // the runtime, but operations like a slice copy can call msanread
-// anyhow for values on the stack.  Just ignore msanread when running
-// on the system stack.  The other msan functions are fine.
+// anyhow for values on the stack. Just ignore msanread when running
+// on the system stack. The other msan functions are fine.
 func msanread(addr unsafe.Pointer, sz uintptr) {
 	g := getg()
 	if g == g.m.g0 || g == g.m.gsignal {
diff --git a/libgo/go/runtime/msan0.go b/libgo/go/runtime/msan0.go
index e2067206976..117c5e5789c 100644
--- a/libgo/go/runtime/msan0.go
+++ b/libgo/go/runtime/msan0.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/mstkbar.go b/libgo/go/runtime/mstkbar.go
index 016625ae925..1bf9d573b70 100644
--- a/libgo/go/runtime/mstkbar.go
+++ b/libgo/go/runtime/mstkbar.go
@@ -214,14 +214,15 @@ func gcInstallStackBarrier(gp *g, frame *stkframe) bool {
 }
 
 // gcRemoveStackBarriers removes all stack barriers installed in gp's stack.
+//
+// gp's stack barriers must be locked.
+//
 //go:nowritebarrier
 func gcRemoveStackBarriers(gp *g) {
 	if debugStackBarrier && gp.stkbarPos != 0 {
 		print("hit ", gp.stkbarPos, " stack barriers, goid=", gp.goid, "\n")
 	}
 
-	gcLockStackBarriers(gp)
-
 	// Remove stack barriers that we didn't hit.
 	for _, stkbar := range gp.stkbar[gp.stkbarPos:] {
 		gcRemoveStackBarrier(gp, stkbar)
@@ -231,8 +232,6 @@ func gcRemoveStackBarriers(gp *g) {
 	// adjust them.
 	gp.stkbarPos = 0
 	gp.stkbar = gp.stkbar[:0]
-
-	gcUnlockStackBarriers(gp)
 }
 
 // gcRemoveStackBarrier removes a single stack barrier. It is the
@@ -258,6 +257,31 @@ func gcRemoveStackBarrier(gp *g, stkbar stkbar) {
 	*lrPtr = sys.Uintreg(stkbar.savedLRVal)
 }
 
+// gcTryRemoveAllStackBarriers tries to remove stack barriers from all
+// Gs in gps. It is best-effort and efficient. If it can't remove
+// barriers from a G immediately, it will simply skip it.
+func gcTryRemoveAllStackBarriers(gps []*g) {
+	for _, gp := range gps {
+	retry:
+		for {
+			switch s := readgstatus(gp); s {
+			default:
+				break retry
+
+			case _Grunnable, _Gsyscall, _Gwaiting:
+				if !castogscanstatus(gp, s, s|_Gscan) {
+					continue
+				}
+				gcLockStackBarriers(gp)
+				gcRemoveStackBarriers(gp)
+				gcUnlockStackBarriers(gp)
+				restartg(gp)
+				break retry
+			}
+		}
+	}
+}
+
 // gcPrintStkbars prints the stack barriers of gp for debugging. It
 // places a "@@@" marker at gp.stkbarPos. If marker >= 0, it will also
 // place a "==>" marker before the marker'th entry.
diff --git a/libgo/go/runtime/norace_test.go b/libgo/go/runtime/norace_test.go
index 3681bf190d2..e9b39b2f455 100644
--- a/libgo/go/runtime/norace_test.go
+++ b/libgo/go/runtime/norace_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// The file contains tests that can not run under race detector for some reason.
+// The file contains tests that cannot run under race detector for some reason.
 // +build !race
 
 package runtime_test
diff --git a/libgo/go/runtime/os1_linux_generic.go b/libgo/go/runtime/os1_linux_generic.go
deleted file mode 100644
index 2c8b743aeb0..00000000000
--- a/libgo/go/runtime/os1_linux_generic.go
+++ /dev/null
@@ -1,27 +0,0 @@
-// Copyright 2009 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build !mips64
-// +build !mips64le
-// +build linux
-
-package runtime
-
-var sigset_all = sigset{^uint32(0), ^uint32(0)}
-
-func sigaddset(mask *sigset, i int) {
-	(*mask)[(i-1)/32] |= 1 << ((uint32(i) - 1) & 31)
-}
-
-func sigdelset(mask *sigset, i int) {
-	(*mask)[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
-}
-
-func sigfillset(mask *uint64) {
-	*mask = ^uint64(0)
-}
-
-func sigcopyset(mask *sigset, m sigmask) {
-	copy((*mask)[:], m[:])
-}
diff --git a/libgo/go/runtime/os1_linux_mips64x.go b/libgo/go/runtime/os1_linux_mips64x.go
deleted file mode 100644
index 701e9791026..00000000000
--- a/libgo/go/runtime/os1_linux_mips64x.go
+++ /dev/null
@@ -1,26 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build mips64 mips64le
-// +build linux
-
-package runtime
-
-var sigset_all = sigset{^uint64(0), ^uint64(0)}
-
-func sigaddset(mask *sigset, i int) {
-	(*mask)[(i-1)/64] |= 1 << ((uint32(i) - 1) & 63)
-}
-
-func sigdelset(mask *sigset, i int) {
-	(*mask)[(i-1)/64] &^= 1 << ((uint32(i) - 1) & 63)
-}
-
-func sigfillset(mask *[2]uint64) {
-	(*mask)[0], (*mask)[1] = ^uint64(0), ^uint64(0)
-}
-
-func sigcopyset(mask *sigset, m sigmask) {
-	(*mask)[0] = uint64(m[0]) | uint64(m[1])<<32
-}
diff --git a/libgo/go/runtime/os2_linux_mips64x.go b/libgo/go/runtime/os2_linux_mips64x.go
deleted file mode 100644
index 9a6a92a87d3..00000000000
--- a/libgo/go/runtime/os2_linux_mips64x.go
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build linux
-// +build mips64 mips64le
-
-package runtime
-
-const (
-	_SS_DISABLE  = 2
-	_NSIG        = 65
-	_SI_USER     = 0
-	_SIG_BLOCK   = 1
-	_SIG_UNBLOCK = 2
-	_SIG_SETMASK = 3
-	_RLIMIT_AS   = 6
-)
-
-type sigset [2]uint64
-
-type rlimit struct {
-	rlim_cur uintptr
-	rlim_max uintptr
-}
diff --git a/libgo/go/runtime/os2_linux_generic.go b/libgo/go/runtime/os_linux_generic.go
index 01e6c8a5ec8..a16d1407761 100644
--- a/libgo/go/runtime/os2_linux_generic.go
+++ b/libgo/go/runtime/os_linux_generic.go
@@ -4,6 +4,7 @@
 
 // +build !mips64
 // +build !mips64le
+// +build !s390x
 // +build linux
 
 package runtime
@@ -27,3 +28,21 @@ type rlimit struct {
 	rlim_cur uintptr
 	rlim_max uintptr
 }
+
+var sigset_all = sigset{^uint32(0), ^uint32(0)}
+
+func sigaddset(mask *sigset, i int) {
+	(*mask)[(i-1)/32] |= 1 << ((uint32(i) - 1) & 31)
+}
+
+func sigdelset(mask *sigset, i int) {
+	(*mask)[(i-1)/32] &^= 1 << ((uint32(i) - 1) & 31)
+}
+
+func sigfillset(mask *uint64) {
+	*mask = ^uint64(0)
+}
+
+func sigcopyset(mask *sigset, m sigmask) {
+	copy((*mask)[:], m[:])
+}
diff --git a/libgo/go/runtime/os_linux_mips64x.go b/libgo/go/runtime/os_linux_mips64x.go
index 4d2e9e8a20a..8039b2fac9b 100644
--- a/libgo/go/runtime/os_linux_mips64x.go
+++ b/libgo/go/runtime/os_linux_mips64x.go
@@ -2,13 +2,24 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build mips64 mips64le
 // +build linux
+// +build mips64 mips64le
 
 package runtime
 
 var randomNumber uint32
 
+func archauxv(tag, val uintptr) {
+	switch tag {
+	case _AT_RANDOM:
+		// sysargs filled in startupRandomData, but that
+		// pointer may not be word aligned, so we must treat
+		// it as a byte array.
+		randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 |
+			uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24
+	}
+}
+
 //go:nosplit
 func cputicks() int64 {
 	// Currently cputicks() is used in blocking profiler and to seed fastrand1().
@@ -16,3 +27,38 @@ func cputicks() int64 {
 	// randomNumber provides better seeding of fastrand1.
 	return nanotime() + int64(randomNumber)
 }
+
+const (
+	_SS_DISABLE  = 2
+	_NSIG        = 65
+	_SI_USER     = 0
+	_SIG_BLOCK   = 1
+	_SIG_UNBLOCK = 2
+	_SIG_SETMASK = 3
+	_RLIMIT_AS   = 6
+)
+
+type sigset [2]uint64
+
+type rlimit struct {
+	rlim_cur uintptr
+	rlim_max uintptr
+}
+
+var sigset_all = sigset{^uint64(0), ^uint64(0)}
+
+func sigaddset(mask *sigset, i int) {
+	(*mask)[(i-1)/64] |= 1 << ((uint32(i) - 1) & 63)
+}
+
+func sigdelset(mask *sigset, i int) {
+	(*mask)[(i-1)/64] &^= 1 << ((uint32(i) - 1) & 63)
+}
+
+func sigfillset(mask *[2]uint64) {
+	(*mask)[0], (*mask)[1] = ^uint64(0), ^uint64(0)
+}
+
+func sigcopyset(mask *sigset, m sigmask) {
+	(*mask)[0] = uint64(m[0]) | uint64(m[1])<<32
+}
diff --git a/libgo/go/runtime/os_linux_noauxv.go b/libgo/go/runtime/os_linux_noauxv.go
new file mode 100644
index 00000000000..22522dd803d
--- /dev/null
+++ b/libgo/go/runtime/os_linux_noauxv.go
@@ -0,0 +1,10 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !amd64,!arm,!arm64,!mips64,!mips64le
+
+package runtime
+
+func archauxv(tag, val uintptr) {
+}
diff --git a/libgo/go/runtime/os_linux_s390x.go b/libgo/go/runtime/os_linux_s390x.go
new file mode 100644
index 00000000000..e659dff7169
--- /dev/null
+++ b/libgo/go/runtime/os_linux_s390x.go
@@ -0,0 +1,46 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+const (
+	_SS_DISABLE  = 2
+	_NSIG        = 65
+	_SI_USER     = 0
+	_SIG_BLOCK   = 0
+	_SIG_UNBLOCK = 1
+	_SIG_SETMASK = 2
+	_RLIMIT_AS   = 9
+)
+
+type sigset uint64
+
+type rlimit struct {
+	rlim_cur uintptr
+	rlim_max uintptr
+}
+
+var sigset_all = sigset(^uint64(0))
+
+func sigaddset(mask *sigset, i int) {
+	if i > 64 {
+		throw("unexpected signal greater than 64")
+	}
+	*mask |= 1 << (uint(i) - 1)
+}
+
+func sigdelset(mask *sigset, i int) {
+	if i > 64 {
+		throw("unexpected signal greater than 64")
+	}
+	*mask &^= 1 << (uint(i) - 1)
+}
+
+func sigfillset(mask *uint64) {
+	*mask = ^uint64(0)
+}
+
+func sigcopyset(mask *sigset, m sigmask) {
+	*mask = sigset(uint64(m[0]) | uint64(m[1])<<32)
+}
diff --git a/libgo/go/runtime/os_netbsd_386.go b/libgo/go/runtime/os_netbsd_386.go
new file mode 100644
index 00000000000..037f7e36dc6
--- /dev/null
+++ b/libgo/go/runtime/os_netbsd_386.go
@@ -0,0 +1,16 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import "unsafe"
+
+func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
+	// Machine dependent mcontext initialisation for LWP.
+	mc.__gregs[_REG_EIP] = uint32(funcPC(lwp_tramp))
+	mc.__gregs[_REG_UESP] = uint32(uintptr(stk))
+	mc.__gregs[_REG_EBX] = uint32(uintptr(unsafe.Pointer(mp)))
+	mc.__gregs[_REG_EDX] = uint32(uintptr(unsafe.Pointer(gp)))
+	mc.__gregs[_REG_ESI] = uint32(fn)
+}
diff --git a/libgo/go/runtime/os_netbsd_amd64.go b/libgo/go/runtime/os_netbsd_amd64.go
new file mode 100644
index 00000000000..5118b0c4ffd
--- /dev/null
+++ b/libgo/go/runtime/os_netbsd_amd64.go
@@ -0,0 +1,16 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import "unsafe"
+
+func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
+	// Machine dependent mcontext initialisation for LWP.
+	mc.__gregs[_REG_RIP] = uint64(funcPC(lwp_tramp))
+	mc.__gregs[_REG_RSP] = uint64(uintptr(stk))
+	mc.__gregs[_REG_R8] = uint64(uintptr(unsafe.Pointer(mp)))
+	mc.__gregs[_REG_R9] = uint64(uintptr(unsafe.Pointer(gp)))
+	mc.__gregs[_REG_R12] = uint64(fn)
+}
diff --git a/libgo/go/runtime/os_plan9_arm.go b/libgo/go/runtime/os_plan9_arm.go
new file mode 100644
index 00000000000..30cde8f74b0
--- /dev/null
+++ b/libgo/go/runtime/os_plan9_arm.go
@@ -0,0 +1,17 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+func checkgoarm() {
+	return // TODO(minux)
+}
+
+//go:nosplit
+func cputicks() int64 {
+	// Currently cputicks() is used in blocking profiler and to seed runtime·fastrand1().
+	// runtime·nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
+	// TODO: need more entropy to better seed fastrand1.
+	return nanotime()
+}
diff --git a/libgo/go/runtime/parfor_test.go b/libgo/go/runtime/parfor_test.go
deleted file mode 100644
index 5d22aecc9bb..00000000000
--- a/libgo/go/runtime/parfor_test.go
+++ /dev/null
@@ -1,128 +0,0 @@
-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// The race detector does not understand ParFor synchronization.
-// +build !race
-
-package runtime_test
-
-import (
-	. "runtime"
-	"testing"
-)
-
-// Simple serial sanity test for parallelfor.
-func TestParFor(t *testing.T) {
-	const P = 1
-	const N = 20
-	data := make([]uint64, N)
-	for i := uint64(0); i < N; i++ {
-		data[i] = i
-	}
-	desc := NewParFor(P)
-	ParForSetup(desc, P, N, true, func(desc *ParFor, i uint32) {
-		data[i] = data[i]*data[i] + 1
-	})
-	ParForDo(desc)
-	for i := uint64(0); i < N; i++ {
-		if data[i] != i*i+1 {
-			t.Fatalf("Wrong element %d: %d", i, data[i])
-		}
-	}
-}
-
-// Test that nonblocking parallelfor does not block.
-func TestParFor2(t *testing.T) {
-	const P = 7
-	const N = 1003
-	data := make([]uint64, N)
-	for i := uint64(0); i < N; i++ {
-		data[i] = i
-	}
-	desc := NewParFor(P)
-	ParForSetup(desc, P, N, false, func(desc *ParFor, i uint32) {
-		data[i] = data[i]*data[i] + 1
-	})
-	for p := 0; p < P; p++ {
-		ParForDo(desc)
-	}
-	for i := uint64(0); i < N; i++ {
-		if data[i] != i*i+1 {
-			t.Fatalf("Wrong element %d: %d", i, data[i])
-		}
-	}
-}
-
-// Test that iterations are properly distributed.
-func TestParForSetup(t *testing.T) {
-	const P = 11
-	const N = 101
-	desc := NewParFor(P)
-	for n := uint32(0); n < N; n++ {
-		for p := uint32(1); p <= P; p++ {
-			ParForSetup(desc, p, n, true, func(desc *ParFor, i uint32) {})
-			sum := uint32(0)
-			size0 := uint32(0)
-			end0 := uint32(0)
-			for i := uint32(0); i < p; i++ {
-				begin, end := ParForIters(desc, i)
-				size := end - begin
-				sum += size
-				if i == 0 {
-					size0 = size
-					if begin != 0 {
-						t.Fatalf("incorrect begin: %d (n=%d, p=%d)", begin, n, p)
-					}
-				} else {
-					if size != size0 && size != size0+1 {
-						t.Fatalf("incorrect size: %d/%d (n=%d, p=%d)", size, size0, n, p)
-					}
-					if begin != end0 {
-						t.Fatalf("incorrect begin/end: %d/%d (n=%d, p=%d)", begin, end0, n, p)
-					}
-				}
-				end0 = end
-			}
-			if sum != n {
-				t.Fatalf("incorrect sum: %d/%d (p=%d)", sum, n, p)
-			}
-		}
-	}
-}
-
-// Test parallel parallelfor.
-func TestParForParallel(t *testing.T) {
-	N := uint64(1e7)
-	if testing.Short() {
-		N /= 10
-	}
-	data := make([]uint64, N)
-	for i := uint64(0); i < N; i++ {
-		data[i] = i
-	}
-	P := GOMAXPROCS(-1)
-	c := make(chan bool, P)
-	desc := NewParFor(uint32(P))
-	ParForSetup(desc, uint32(P), uint32(N), false, func(desc *ParFor, i uint32) {
-		data[i] = data[i]*data[i] + 1
-	})
-	for p := 1; p < P; p++ {
-		go func() {
-			ParForDo(desc)
-			c <- true
-		}()
-	}
-	ParForDo(desc)
-	for p := 1; p < P; p++ {
-		<-c
-	}
-	for i := uint64(0); i < N; i++ {
-		if data[i] != i*i+1 {
-			t.Fatalf("Wrong element %d: %d", i, data[i])
-		}
-	}
-
-	data, desc = nil, nil
-	GC()
-}
diff --git a/libgo/go/runtime/pprof/mprof_test.go b/libgo/go/runtime/pprof/mprof_test.go
index bfa7b3b4747..54daefa23d7 100644
--- a/libgo/go/runtime/pprof/mprof_test.go
+++ b/libgo/go/runtime/pprof/mprof_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/pprof/pprof.go b/libgo/go/runtime/pprof/pprof.go
index 18e99366fb3..d2e5b63fedb 100644
--- a/libgo/go/runtime/pprof/pprof.go
+++ b/libgo/go/runtime/pprof/pprof.go
@@ -1,11 +1,11 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Package pprof writes runtime profiling data in the format expected
 // by the pprof visualization tool.
 // For more information about pprof, see
-// http://code.google.com/p/google-perftools/.
+// http://github.com/google/pprof/.
 package pprof
 
 import (
@@ -13,6 +13,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"os"
 	"runtime"
 	"sort"
 	"strings"
@@ -31,7 +32,7 @@ import (
 //
 // A Profile's methods can be called from multiple goroutines simultaneously.
 //
-// Each Profile has a unique name.  A few profiles are predefined:
+// Each Profile has a unique name. A few profiles are predefined:
 //
 //	goroutine    - stack traces of all current goroutines
 //	heap         - a sampling of all heap allocations
@@ -48,7 +49,7 @@ import (
 // all known allocations. This exception helps mainly in programs running
 // without garbage collection enabled, usually for debugging purposes.
 //
-// The CPU profile is not available as a Profile.  It has a special API,
+// The CPU profile is not available as a Profile. It has a special API,
 // the StartCPUProfile and StopCPUProfile functions, because it streams
 // output to a writer during profiling.
 //
@@ -173,11 +174,11 @@ func (p *Profile) Count() int {
 // Add adds the current execution stack to the profile, associated with value.
 // Add stores value in an internal map, so value must be suitable for use as
 // a map key and will not be garbage collected until the corresponding
-// call to Remove.  Add panics if the profile already contains a stack for value.
+// call to Remove. Add panics if the profile already contains a stack for value.
 //
 // The skip parameter has the same meaning as runtime.Caller's skip
-// and controls where the stack trace begins.  Passing skip=0 begins the
-// trace in the function calling Add.  For example, given this
+// and controls where the stack trace begins. Passing skip=0 begins the
+// trace in the function calling Add. For example, given this
 // execution stack:
 //
 //	Add
@@ -266,7 +267,7 @@ func (x stackProfile) Less(i, j int) bool {
 }
 
 // A countProfile is a set of stack traces to be printed as counts
-// grouped by stack trace.  There are multiple implementations:
+// grouped by stack trace. There are multiple implementations:
 // all that matters is that we can find out how many traces there are
 // and obtain each trace in turn.
 type countProfile interface {
@@ -296,22 +297,25 @@ func printCountProfile(w io.Writer, debug int, name string, p countProfile) erro
 		}
 		return buf.String()
 	}
-	m := map[string]int{}
+	count := map[string]int{}
+	index := map[string]int{}
+	var keys []string
 	n := p.Len()
 	for i := 0; i < n; i++ {
-		m[key(p.Stack(i))]++
+		k := key(p.Stack(i))
+		if count[k] == 0 {
+			index[k] = i
+			keys = append(keys, k)
+		}
+		count[k]++
 	}
 
-	// Print stacks, listing count on first occurrence of a unique stack.
-	for i := 0; i < n; i++ {
-		stk := p.Stack(i)
-		s := key(stk)
-		if count := m[s]; count != 0 {
-			fmt.Fprintf(w, "%d %s\n", count, s)
-			if debug > 0 {
-				printStackRecord(w, stk, false)
-			}
-			delete(m, s)
+	sort.Sort(&keysByCount{keys, count})
+
+	for _, k := range keys {
+		fmt.Fprintf(w, "%d %s\n", count[k], k)
+		if debug > 0 {
+			printStackRecord(w, p.Stack(index[k]), false)
 		}
 	}
 
@@ -321,49 +325,56 @@ func printCountProfile(w io.Writer, debug int, name string, p countProfile) erro
 	return b.Flush()
 }
 
+// keysByCount sorts keys with higher counts first, breaking ties by key string order.
+type keysByCount struct {
+	keys  []string
+	count map[string]int
+}
+
+func (x *keysByCount) Len() int      { return len(x.keys) }
+func (x *keysByCount) Swap(i, j int) { x.keys[i], x.keys[j] = x.keys[j], x.keys[i] }
+func (x *keysByCount) Less(i, j int) bool {
+	ki, kj := x.keys[i], x.keys[j]
+	ci, cj := x.count[ki], x.count[kj]
+	if ci != cj {
+		return ci > cj
+	}
+	return ki < kj
+}
+
 // printStackRecord prints the function + source line information
 // for a single stack trace.
 func printStackRecord(w io.Writer, stk []uintptr, allFrames bool) {
 	show := allFrames
-	wasPanic := false
-	for i, pc := range stk {
-		f := runtime.FuncForPC(pc)
-		if f == nil {
-			show = true
-			fmt.Fprintf(w, "#\t%#x\n", pc)
-			wasPanic = false
-		} else {
-			tracepc := pc
-			// Back up to call instruction.
-			if i > 0 && pc > f.Entry() && !wasPanic {
-				if runtime.GOARCH == "386" || runtime.GOARCH == "amd64" {
-					tracepc--
-				} else if runtime.GOARCH == "s390" || runtime.GOARCH == "s390x" {
-					// only works if function was called
-					// with the brasl instruction (or a
-					// different 6-byte instruction).
-					tracepc -= 6
-				} else {
-					tracepc -= 4 // arm, etc
-				}
-			}
-			file, line := f.FileLine(tracepc)
-			name := f.Name()
-			// Hide runtime.goexit and any runtime functions at the beginning.
-			// This is useful mainly for allocation traces.
-			wasPanic = name == "runtime.gopanic"
-			if name == "runtime.goexit" || !show && (strings.HasPrefix(name, "runtime.") || strings.HasPrefix(name, "runtime_")) {
-				continue
-			}
-			if !show && !strings.Contains(name, ".") && strings.HasPrefix(name, "__go_") {
-				continue
-			}
-			if !show && name == "" {
-				// This can happen due to http://gcc.gnu.org/PR65797.
-				continue
+	frames := runtime.CallersFrames(stk)
+	for {
+		frame, more := frames.Next()
+		name := frame.Function
+
+		// Hide runtime.goexit and any runtime functions at the beginning.
+		// This is useful mainly for allocation traces.
+		skip := name == "runtime.goexit"
+		if !show {
+			switch {
+			case strings.HasPrefix(name, "runtime."):
+				skip = true
+			case strings.HasPrefix(name, "runtime_"):
+				skip = true
+			case !strings.Contains(name, ".") && strings.HasPrefix(name, "__go_"):
+				skip = true
 			}
+		}
+
+		if !show && name == "" {
+			// This can happen due to http://gcc.gnu.org/PR65797.
+		} else if name == "" {
+			fmt.Fprintf(w, "#\t%#x\n", frame.PC)
+		} else if !skip {
 			show = true
-			fmt.Fprintf(w, "#\t%#x\t%s+%#x\t%s:%d\n", pc, name, pc-f.Entry(), file, line)
+			fmt.Fprintf(w, "#\t%#x\t%s+%#x\t%s:%d\n", frame.PC, name, frame.PC-frame.Entry, frame.File, frame.Line)
+		}
+		if !more {
+			break
 		}
 	}
 	if !show {
@@ -486,7 +497,6 @@ func writeHeap(w io.Writer, debug int) error {
 	fmt.Fprintf(w, "# NextGC = %d\n", s.NextGC)
 	fmt.Fprintf(w, "# PauseNs = %d\n", s.PauseNs)
 	fmt.Fprintf(w, "# NumGC = %d\n", s.NumGC)
-	fmt.Fprintf(w, "# EnableGC = %v\n", s.EnableGC)
 	fmt.Fprintf(w, "# DebugGC = %v\n", s.DebugGC)
 
 	if tw != nil {
@@ -521,7 +531,7 @@ func writeGoroutine(w io.Writer, debug int) error {
 
 func writeGoroutineStacks(w io.Writer) error {
 	// We don't know how big the buffer needs to be to collect
-	// all the goroutines.  Start with 1 MB and try a few times, doubling each time.
+	// all the goroutines. Start with 1 MB and try a few times, doubling each time.
 	// Give up and use a truncated trace if 64 MB is not enough.
 	buf := make([]byte, 1<<20)
 	for i := 0; ; i++ {
@@ -584,7 +594,7 @@ var cpu struct {
 // Go code built with -buildmode=c-archive or -buildmode=c-shared.
 // StartCPUProfile relies on the SIGPROF signal, but that signal will
 // be delivered to the main program's SIGPROF signal handler (if any)
-// not to the one used by Go.  To make it work, call os/signal.Notify
+// not to the one used by Go. To make it work, call os/signal.Notify
 // for syscall.SIGPROF, but note that doing so may break any profiling
 // being done by the main program.
 func StartCPUProfile(w io.Writer) error {
@@ -595,7 +605,7 @@ func StartCPUProfile(w io.Writer) error {
 	// 100 Hz is a reasonable choice: it is frequent enough to
 	// produce useful data, rare enough not to bog down the
 	// system, and a nice round number to make it easy to
-	// convert sample counts to seconds.  Instead of requiring
+	// convert sample counts to seconds. Instead of requiring
 	// each client to specify the frequency, we hard code it.
 	const hz = 100
 
@@ -622,6 +632,42 @@ func profileWriter(w io.Writer) {
 		}
 		w.Write(data)
 	}
+
+	// We are emitting the legacy profiling format, which permits
+	// a memory map following the CPU samples. The memory map is
+	// simply a copy of the GNU/Linux /proc/self/maps file. The
+	// profiler uses the memory map to map PC values in shared
+	// libraries to a shared library in the filesystem, in order
+	// to report the correct function and, if the shared library
+	// has debug info, file/line. This is particularly useful for
+	// PIE (position independent executables) as on ELF systems a
+	// PIE is simply an executable shared library.
+	//
+	// Because the profiling format expects the memory map in
+	// GNU/Linux format, we only do this on GNU/Linux for now. To
+	// add support for profiling PIE on other ELF-based systems,
+	// it may be necessary to map the system-specific mapping
+	// information to the GNU/Linux format. For a reasonably
+	// portable C++ version, see the FillProcSelfMaps function in
+	// https://github.com/gperftools/gperftools/blob/master/src/base/sysinfo.cc
+	//
+	// The code that parses this mapping for the pprof tool is
+	// ParseMemoryMap in cmd/internal/pprof/legacy_profile.go, but
+	// don't change that code, as similar code exists in other
+	// (non-Go) pprof readers. Change this code so that that code works.
+	//
+	// We ignore errors reading or copying the memory map; the
+	// profile is likely usable without it, and we have no good way
+	// to report errors.
+	if runtime.GOOS == "linux" {
+		f, err := os.Open("/proc/self/maps")
+		if err == nil {
+			io.WriteString(w, "\nMAPPED_LIBRARIES:\n")
+			io.Copy(w, f)
+			f.Close()
+		}
+	}
+
 	cpu.done <- true
 }
 
diff --git a/libgo/go/runtime/pprof/pprof_test.go b/libgo/go/runtime/pprof/pprof_test.go
index e384e11eda0..1692d4210b7 100644
--- a/libgo/go/runtime/pprof/pprof_test.go
+++ b/libgo/go/runtime/pprof/pprof_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -86,10 +86,14 @@ func TestCPUProfileMultithreaded(t *testing.T) {
 	})
 }
 
-func parseProfile(t *testing.T, bytes []byte, f func(uintptr, []uintptr)) {
+func parseProfile(t *testing.T, valBytes []byte, f func(uintptr, []uintptr)) {
 	// Convert []byte to []uintptr.
-	l := len(bytes) / int(unsafe.Sizeof(uintptr(0)))
-	val := *(*[]uintptr)(unsafe.Pointer(&bytes))
+	l := len(valBytes)
+	if i := bytes.Index(valBytes, []byte("\nMAPPED_LIBRARIES:\n")); i >= 0 {
+		l = i
+	}
+	l /= int(unsafe.Sizeof(uintptr(0)))
+	val := *(*[]uintptr)(unsafe.Pointer(&valBytes))
 	val = val[:l]
 
 	// 5 for the header, 3 for the trailer.
@@ -389,7 +393,7 @@ func TestStackBarrierProfiling(t *testing.T) {
 			args = append(args, "-test.short")
 		}
 		cmd := exec.Command(os.Args[0], args...)
-		cmd.Env = append([]string{"GODEBUG=gcstackbarrierall=1", "GOGC=1"}, os.Environ()...)
+		cmd.Env = append([]string{"GODEBUG=gcstackbarrierall=1", "GOGC=1", "GOTRACEBACK=system"}, os.Environ()...)
 		if out, err := cmd.CombinedOutput(); err != nil {
 			t.Fatalf("subprocess failed with %v:\n%s", err, out)
 		}
@@ -495,6 +499,10 @@ func TestBlockProfile(t *testing.T) {
 		t.Fatalf("Bad profile header:\n%v", prof)
 	}
 
+	if strings.HasSuffix(prof, "#\t0x0\n\n") {
+		t.Errorf("Useless 0 suffix:\n%v", prof)
+	}
+
 	for _, test := range tests {
 		if !regexp.MustCompile(strings.Replace(test.re, "\t", "\t+", -1)).MatchString(prof) {
 			t.Fatalf("Bad %v entry, expect:\n%v\ngot:\n%v", test.name, test.re, prof)
@@ -532,15 +540,20 @@ func blockChanClose() {
 }
 
 func blockSelectRecvAsync() {
+	const numTries = 3
 	c := make(chan bool, 1)
 	c2 := make(chan bool, 1)
 	go func() {
-		time.Sleep(blockDelay)
-		c <- true
+		for i := 0; i < numTries; i++ {
+			time.Sleep(blockDelay)
+			c <- true
+		}
 	}()
-	select {
-	case <-c:
-	case <-c2:
+	for i := 0; i < numTries; i++ {
+		select {
+		case <-c:
+		case <-c2:
+		}
 	}
 }
 
@@ -580,3 +593,53 @@ func blockCond() {
 	c.Wait()
 	mu.Unlock()
 }
+
+func func1(c chan int) { <-c }
+func func2(c chan int) { <-c }
+func func3(c chan int) { <-c }
+func func4(c chan int) { <-c }
+
+func TestGoroutineCounts(t *testing.T) {
+	if runtime.Compiler == "gccgo" {
+		t.Skip("goroutine stacks not supported on gccgo")
+	}
+	if runtime.GOOS == "openbsd" {
+		testenv.SkipFlaky(t, 15156)
+	}
+	c := make(chan int)
+	for i := 0; i < 100; i++ {
+		if i%10 == 0 {
+			go func1(c)
+			continue
+		}
+		if i%2 == 0 {
+			go func2(c)
+			continue
+		}
+		go func3(c)
+	}
+	time.Sleep(10 * time.Millisecond) // let goroutines block on channel
+
+	var w bytes.Buffer
+	Lookup("goroutine").WriteTo(&w, 1)
+	prof := w.String()
+
+	if !containsInOrder(prof, "\n50 @ ", "\n40 @", "\n10 @", "\n1 @") {
+		t.Errorf("expected sorted goroutine counts:\n%s", prof)
+	}
+
+	close(c)
+
+	time.Sleep(10 * time.Millisecond) // let goroutines exit
+}
+
+func containsInOrder(s string, all ...string) bool {
+	for _, t := range all {
+		i := strings.Index(s, t)
+		if i < 0 {
+			return false
+		}
+		s = s[i+len(t):]
+	}
+	return true
+}
diff --git a/libgo/go/runtime/print.go b/libgo/go/runtime/print.go
index f789f890835..32626c1e9df 100644
--- a/libgo/go/runtime/print.go
+++ b/libgo/go/runtime/print.go
@@ -209,7 +209,7 @@ func printstring(s string) {
 func printslice(s []byte) {
 	sp := (*slice)(unsafe.Pointer(&s))
 	print("[", len(s), "/", cap(s), "]")
-	printpointer(unsafe.Pointer(sp.array))
+	printpointer(sp.array)
 }
 
 func printeface(e eface) {
diff --git a/libgo/go/runtime/proc_runtime_test.go b/libgo/go/runtime/proc_runtime_test.go
new file mode 100644
index 00000000000..d56f9b14636
--- /dev/null
+++ b/libgo/go/runtime/proc_runtime_test.go
@@ -0,0 +1,35 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+// Proc unit tests. In runtime package so can use runtime guts.
+
+package runtime
+
+func RunStealOrderTest() {
+	var ord randomOrder
+	for procs := 1; procs <= 64; procs++ {
+		ord.reset(uint32(procs))
+		if procs >= 3 && len(ord.coprimes) < 2 {
+			panic("too few coprimes")
+		}
+		for co := 0; co < len(ord.coprimes); co++ {
+			enum := ord.start(uint32(co))
+			checked := make([]bool, procs)
+			for p := 0; p < procs; p++ {
+				x := enum.position()
+				if checked[x] {
+					println("procs:", procs, "inc:", enum.inc)
+					panic("duplicate during enumeration")
+				}
+				checked[x] = true
+				enum.next()
+			}
+			if !enum.done() {
+				panic("not done")
+			}
+		}
+	}
+}
diff --git a/libgo/go/runtime/proc_test.go b/libgo/go/runtime/proc_test.go
index 37adad570b7..cc390174a74 100644
--- a/libgo/go/runtime/proc_test.go
+++ b/libgo/go/runtime/proc_test.go
@@ -178,7 +178,14 @@ func testGoroutineParallelism2(t *testing.T, load, netpoll bool) {
 		}
 		if netpoll {
 			// Enable netpoller, affects schedler behavior.
-			ln, err := net.Listen("tcp", "localhost:0")
+			laddr := "localhost:0"
+			if runtime.GOOS == "android" {
+				// On some Android devices, there are no records for localhost,
+				// see https://golang.org/issues/14486.
+				// Don't use 127.0.0.1 for every case, it won't work on IPv6-only systems.
+				laddr = "127.0.0.1:0"
+			}
+			ln, err := net.Listen("tcp", laddr)
 			if err != nil {
 				defer ln.Close() // yup, defer in a loop
 			}
@@ -339,6 +346,14 @@ func TestGCFairness(t *testing.T) {
 	}
 }
 
+func TestGCFairness2(t *testing.T) {
+	output := runTestProg(t, "testprog", "GCFairness2")
+	want := "OK\n"
+	if output != want {
+		t.Fatalf("want %s, got %s\n", want, output)
+	}
+}
+
 func TestNumGoroutine(t *testing.T) {
 	output := runTestProg(t, "testprog", "NumGoroutine")
 	want := "1\n"
@@ -423,6 +438,9 @@ func TestPingPongHog(t *testing.T) {
 }
 
 func BenchmarkPingPongHog(b *testing.B) {
+	if b.N == 0 {
+		return
+	}
 	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
 
 	// Create a CPU hog
@@ -550,6 +568,26 @@ func TestSchedLocalQueueSteal(t *testing.T) {
 }
 */
 
+/*
+func TestSchedLocalQueueEmpty(t *testing.T) {
+	if runtime.NumCPU() == 1 {
+		// Takes too long and does not trigger the race.
+		t.Skip("skipping on uniprocessor")
+	}
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
+
+	// If runtime triggers a forced GC during this test then it will deadlock,
+	// since the goroutines can't be stopped/preempted during spin wait.
+	defer debug.SetGCPercent(debug.SetGCPercent(-1))
+
+	iters := int(1e5)
+	if testing.Short() {
+		iters = 1e2
+	}
+	runtime.RunSchedLocalQueueEmptyTest(iters)
+}
+*/
+
 func benchmarkStackGrowth(b *testing.B, rec int) {
 	b.RunParallel(func(pb *testing.PB) {
 		for pb.Next() {
@@ -686,3 +724,9 @@ func matmult(done chan<- struct{}, A, B, C Matrix, i0, i1, j0, j1, k0, k1, thres
 		done <- struct{}{}
 	}
 }
+
+/*
+func TestStealOrder(t *testing.T) {
+	runtime.RunStealOrderTest()
+}
+*/
diff --git a/libgo/go/runtime/race/race_linux_test.go b/libgo/go/runtime/race/race_linux_test.go
new file mode 100644
index 00000000000..c00ce4d3dfc
--- /dev/null
+++ b/libgo/go/runtime/race/race_linux_test.go
@@ -0,0 +1,37 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux,race
+
+package race_test
+
+import (
+	"sync/atomic"
+	"syscall"
+	"testing"
+	"unsafe"
+)
+
+func TestAtomicMmap(t *testing.T) {
+	// Test that atomic operations work on "external" memory. Previously they crashed (#16206).
+	// Also do a sanity correctness check: under race detector atomic operations
+	// are implemented inside of race runtime.
+	mem, err := syscall.Mmap(-1, 0, 1<<20, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
+	if err != nil {
+		t.Fatalf("mmap failed: %v", err)
+	}
+	defer syscall.Munmap(mem)
+	a := (*uint64)(unsafe.Pointer(&mem[0]))
+	if *a != 0 {
+		t.Fatalf("bad atomic value: %v, want 0", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 1 {
+		t.Fatalf("bad atomic value: %v, want 1", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 2 {
+		t.Fatalf("bad atomic value: %v, want 2", *a)
+	}
+}
diff --git a/libgo/go/runtime/race/race_windows_test.go b/libgo/go/runtime/race/race_windows_test.go
new file mode 100644
index 00000000000..307a1ea6c0d
--- /dev/null
+++ b/libgo/go/runtime/race/race_windows_test.go
@@ -0,0 +1,46 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows,race
+
+package race_test
+
+import (
+	"sync/atomic"
+	"syscall"
+	"testing"
+	"unsafe"
+)
+
+func TestAtomicMmap(t *testing.T) {
+	// Test that atomic operations work on "external" memory. Previously they crashed (#16206).
+	// Also do a sanity correctness check: under race detector atomic operations
+	// are implemented inside of race runtime.
+	kernel32 := syscall.NewLazyDLL("kernel32.dll")
+	VirtualAlloc := kernel32.NewProc("VirtualAlloc")
+	VirtualFree := kernel32.NewProc("VirtualFree")
+	const (
+		MEM_COMMIT     = 0x00001000
+		MEM_RESERVE    = 0x00002000
+		MEM_RELEASE    = 0x8000
+		PAGE_READWRITE = 0x04
+	)
+	mem, _, err := syscall.Syscall6(VirtualAlloc.Addr(), 4, 0, 1<<20, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE, 0, 0)
+	if err != 0 {
+		t.Fatalf("VirtualAlloc failed: %v", err)
+	}
+	defer syscall.Syscall(VirtualFree.Addr(), 3, mem, 1<<20, MEM_RELEASE)
+	a := (*uint64)(unsafe.Pointer(mem))
+	if *a != 0 {
+		t.Fatalf("bad atomic value: %v, want 0", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 1 {
+		t.Fatalf("bad atomic value: %v, want 1", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 2 {
+		t.Fatalf("bad atomic value: %v, want 2", *a)
+	}
+}
diff --git a/libgo/go/runtime/runtime-lldb_test.go b/libgo/go/runtime/runtime-lldb_test.go
index 2bd91c1ec03..4c379b9cdc2 100644
--- a/libgo/go/runtime/runtime-lldb_test.go
+++ b/libgo/go/runtime/runtime-lldb_test.go
@@ -232,7 +232,7 @@ func verifyAranges(t *testing.T, byteorder binary.ByteOrder, data io.ReadSeeker)
 		SegmentSize uint8
 	}
 	for {
-		offset, err := data.Seek(0, 1)
+		offset, err := data.Seek(0, io.SeekCurrent)
 		if err != nil {
 			t.Fatalf("Seek error: %v", err)
 		}
@@ -246,7 +246,7 @@ func verifyAranges(t *testing.T, byteorder binary.ByteOrder, data io.ReadSeeker)
 		if lastTupleOffset%tupleSize != 0 {
 			t.Fatalf("Invalid arange length %d, (addr %d, seg %d)", header.UnitLength, header.AddressSize, header.SegmentSize)
 		}
-		if _, err = data.Seek(lastTupleOffset, 0); err != nil {
+		if _, err = data.Seek(lastTupleOffset, io.SeekStart); err != nil {
 			t.Fatalf("Seek error: %v", err)
 		}
 		buf := make([]byte, tupleSize)
diff --git a/libgo/go/runtime/runtime_mmap_test.go b/libgo/go/runtime/runtime_mmap_test.go
index 3995305052b..97b44e2660d 100644
--- a/libgo/go/runtime/runtime_mmap_test.go
+++ b/libgo/go/runtime/runtime_mmap_test.go
@@ -1,4 +1,4 @@
-// Copyright 2016 The Go Authors.  All rights reserved.
+// Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/runtime_test.go b/libgo/go/runtime/runtime_test.go
index a520f563475..2ea2dc22b6f 100644
--- a/libgo/go/runtime/runtime_test.go
+++ b/libgo/go/runtime/runtime_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -104,7 +104,7 @@ func TestStopCPUProfilingWithProfilerOff(t *testing.T) {
 // of the larger addresses must themselves be invalid addresses.
 // We might get unlucky and the OS might have mapped one of these
 // addresses, but probably not: they're all in the first page, very high
-// adderesses that normally an OS would reserve for itself, or malformed
+// addresses that normally an OS would reserve for itself, or malformed
 // addresses. Even so, we might have to remove one or two on different
 // systems. We will see.
 
@@ -249,8 +249,8 @@ func TestBadOpen(t *testing.T) {
 	if GOOS == "windows" || GOOS == "nacl" {
 		t.Skip("skipping OS that doesn't have open/read/write/close")
 	}
-	// make sure we get the correct error code if open fails.  Same for
-	// read/write/close on the resulting -1 fd.  See issue 10052.
+	// make sure we get the correct error code if open fails. Same for
+	// read/write/close on the resulting -1 fd. See issue 10052.
 	nonfile := []byte("/notreallyafile")
 	fd := Open(&nonfile[0], 0, 0)
 	if fd != -1 {
diff --git a/libgo/go/runtime/runtime_unix_test.go b/libgo/go/runtime/runtime_unix_test.go
index cfec3326bd7..e91216365ef 100644
--- a/libgo/go/runtime/runtime_unix_test.go
+++ b/libgo/go/runtime/runtime_unix_test.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/signal2_unix.go b/libgo/go/runtime/signal2_unix.go
index 3fe625f83cc..b1371699407 100644
--- a/libgo/go/runtime/signal2_unix.go
+++ b/libgo/go/runtime/signal2_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,7 +12,7 @@ import "unsafe"
 func sigfwd(fn uintptr, sig uint32, info *siginfo, ctx unsafe.Pointer)
 
 // Determines if the signal should be handled by Go and if not, forwards the
-// signal to the handler that was installed before Go's.  Returns whether the
+// signal to the handler that was installed before Go's. Returns whether the
 // signal was forwarded.
 // This is called by the signal handler, and the world may be stopped.
 //go:nosplit
@@ -54,7 +54,7 @@ func sigfwdgo(sig uint32, info *siginfo, ctx unsafe.Pointer) bool {
 	if c.sigcode() == _SI_USER || flags&_SigPanic == 0 {
 		return false
 	}
-	// Determine if the signal occurred inside Go code.  We test that:
+	// Determine if the signal occurred inside Go code. We test that:
 	//   (1) we were in a goroutine (i.e., m.curg != nil), and
 	//   (2) we weren't in CGO (i.e., m.curg.syscallsp == 0).
 	g := getg()
diff --git a/libgo/go/runtime/signal_linux_mips64x.go b/libgo/go/runtime/signal_linux_mips64x.go
index 671b9167b83..0f590e49eab 100644
--- a/libgo/go/runtime/signal_linux_mips64x.go
+++ b/libgo/go/runtime/signal_linux_mips64x.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/signal_linux_s390x.go b/libgo/go/runtime/signal_linux_s390x.go
new file mode 100644
index 00000000000..155d3a326f5
--- /dev/null
+++ b/libgo/go/runtime/signal_linux_s390x.go
@@ -0,0 +1,208 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import (
+	"runtime/internal/sys"
+	"unsafe"
+)
+
+type sigctxt struct {
+	info *siginfo
+	ctxt unsafe.Pointer
+}
+
+func (c *sigctxt) regs() *sigcontext {
+	return (*sigcontext)(unsafe.Pointer(&(*ucontext)(c.ctxt).uc_mcontext))
+}
+func (c *sigctxt) r0() uint64      { return c.regs().gregs[0] }
+func (c *sigctxt) r1() uint64      { return c.regs().gregs[1] }
+func (c *sigctxt) r2() uint64      { return c.regs().gregs[2] }
+func (c *sigctxt) r3() uint64      { return c.regs().gregs[3] }
+func (c *sigctxt) r4() uint64      { return c.regs().gregs[4] }
+func (c *sigctxt) r5() uint64      { return c.regs().gregs[5] }
+func (c *sigctxt) r6() uint64      { return c.regs().gregs[6] }
+func (c *sigctxt) r7() uint64      { return c.regs().gregs[7] }
+func (c *sigctxt) r8() uint64      { return c.regs().gregs[8] }
+func (c *sigctxt) r9() uint64      { return c.regs().gregs[9] }
+func (c *sigctxt) r10() uint64     { return c.regs().gregs[10] }
+func (c *sigctxt) r11() uint64     { return c.regs().gregs[11] }
+func (c *sigctxt) r12() uint64     { return c.regs().gregs[12] }
+func (c *sigctxt) r13() uint64     { return c.regs().gregs[13] }
+func (c *sigctxt) r14() uint64     { return c.regs().gregs[14] }
+func (c *sigctxt) r15() uint64     { return c.regs().gregs[15] }
+func (c *sigctxt) link() uint64    { return c.regs().gregs[14] }
+func (c *sigctxt) sp() uint64      { return c.regs().gregs[15] }
+func (c *sigctxt) pc() uint64      { return c.regs().psw_addr }
+func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
+func (c *sigctxt) sigaddr() uint64 { return c.info.si_addr }
+
+func (c *sigctxt) set_r0(x uint64)      { c.regs().gregs[0] = x }
+func (c *sigctxt) set_r13(x uint64)     { c.regs().gregs[13] = x }
+func (c *sigctxt) set_link(x uint64)    { c.regs().gregs[14] = x }
+func (c *sigctxt) set_sp(x uint64)      { c.regs().gregs[15] = x }
+func (c *sigctxt) set_pc(x uint64)      { c.regs().psw_addr = x }
+func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
+func (c *sigctxt) set_sigaddr(x uint64) {
+	*(*uintptr)(add(unsafe.Pointer(c.info), 2*sys.PtrSize)) = uintptr(x)
+}
+
+func dumpregs(c *sigctxt) {
+	print("r0   ", hex(c.r0()), "\t")
+	print("r1   ", hex(c.r1()), "\n")
+	print("r2   ", hex(c.r2()), "\t")
+	print("r3   ", hex(c.r3()), "\n")
+	print("r4   ", hex(c.r4()), "\t")
+	print("r5   ", hex(c.r5()), "\n")
+	print("r6   ", hex(c.r6()), "\t")
+	print("r7   ", hex(c.r7()), "\n")
+	print("r8   ", hex(c.r8()), "\t")
+	print("r9   ", hex(c.r9()), "\n")
+	print("r10  ", hex(c.r10()), "\t")
+	print("r11  ", hex(c.r11()), "\n")
+	print("r12  ", hex(c.r12()), "\t")
+	print("r13  ", hex(c.r13()), "\n")
+	print("r14  ", hex(c.r14()), "\t")
+	print("r15  ", hex(c.r15()), "\n")
+	print("pc   ", hex(c.pc()), "\t")
+	print("link ", hex(c.link()), "\n")
+}
+
+var crashing int32
+
+// May run during STW, so write barriers are not allowed.
+//
+//go:nowritebarrierrec
+func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
+	_g_ := getg()
+	c := &sigctxt{info, ctxt}
+
+	if sig == _SIGPROF {
+		sigprof(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp, _g_.m)
+		return
+	}
+	flags := int32(_SigThrow)
+	if sig < uint32(len(sigtable)) {
+		flags = sigtable[sig].flags
+	}
+	if c.sigcode() != _SI_USER && flags&_SigPanic != 0 {
+		// Make it look like a call to the signal func.
+		// Have to pass arguments out of band since
+		// augmenting the stack frame would break
+		// the unwinding code.
+		gp.sig = sig
+		gp.sigcode0 = uintptr(c.sigcode())
+		gp.sigcode1 = uintptr(c.sigaddr())
+		gp.sigpc = uintptr(c.pc())
+
+		// We arrange link, and pc to pretend the panicking
+		// function calls sigpanic directly.
+		// Always save LINK to stack so that panics in leaf
+		// functions are correctly handled. This smashes
+		// the stack frame but we're not going back there
+		// anyway.
+		sp := c.sp() - sys.MinFrameSize
+		c.set_sp(sp)
+		*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
+
+		pc := uintptr(gp.sigpc)
+
+		// If we don't recognize the PC as code
+		// but we do recognize the link register as code,
+		// then assume this was a call to non-code and treat like
+		// pc == 0, to make unwinding show the context.
+		if pc != 0 && findfunc(pc) == nil && findfunc(uintptr(c.link())) != nil {
+			pc = 0
+		}
+
+		// Don't bother saving PC if it's zero, which is
+		// probably a call to a nil func: the old link register
+		// is more useful in the stack trace.
+		if pc != 0 {
+			c.set_link(uint64(pc))
+		}
+
+		// In case we are panicking from external C code
+		c.set_r0(0)
+		c.set_r13(uint64(uintptr(unsafe.Pointer(gp))))
+		c.set_pc(uint64(funcPC(sigpanic)))
+		return
+	}
+
+	if c.sigcode() == _SI_USER || flags&_SigNotify != 0 {
+		if sigsend(sig) {
+			return
+		}
+	}
+
+	if c.sigcode() == _SI_USER && signal_ignored(sig) {
+		return
+	}
+
+	if flags&_SigKill != 0 {
+		dieFromSignal(int32(sig))
+	}
+
+	if flags&_SigThrow == 0 {
+		return
+	}
+
+	_g_.m.throwing = 1
+	_g_.m.caughtsig.set(gp)
+
+	if crashing == 0 {
+		startpanic()
+	}
+
+	if sig < uint32(len(sigtable)) {
+		print(sigtable[sig].name, "\n")
+	} else {
+		print("Signal ", sig, "\n")
+	}
+
+	print("PC=", hex(c.pc()), " m=", _g_.m.id, "\n")
+	if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
+		print("signal arrived during cgo execution\n")
+		gp = _g_.m.lockedg
+	}
+	print("\n")
+
+	level, _, docrash := gotraceback()
+	if level > 0 {
+		goroutineheader(gp)
+		tracebacktrap(uintptr(c.pc()), uintptr(c.sp()), uintptr(c.link()), gp)
+		if crashing > 0 && gp != _g_.m.curg && _g_.m.curg != nil && readgstatus(_g_.m.curg)&^_Gscan == _Grunning {
+			// tracebackothers on original m skipped this one; trace it now.
+			goroutineheader(_g_.m.curg)
+			traceback(^uintptr(0), ^uintptr(0), 0, gp)
+		} else if crashing == 0 {
+			tracebackothers(gp)
+			print("\n")
+		}
+		dumpregs(c)
+	}
+
+	if docrash {
+		crashing++
+		if crashing < sched.mcount {
+			// There are other m's that need to dump their stacks.
+			// Relay SIGQUIT to the next m by sending it to the current process.
+			// All m's that have already received SIGQUIT have signal masks blocking
+			// receipt of any signals, so the SIGQUIT will go to an m that hasn't seen it yet.
+			// When the last m receives the SIGQUIT, it will fall through to the call to
+			// crash below. Just in case the relaying gets botched, each m involved in
+			// the relay sleeps for 5 seconds and then does the crash/exit itself.
+			// In expected operation, the last m has received the SIGQUIT and run
+			// crash/exit and the process is gone, all long before any of the
+			// 5-second sleeps have finished.
+			print("\n-----\n\n")
+			raiseproc(_SIGQUIT)
+			usleep(5 * 1000 * 1000)
+		}
+		crash()
+	}
+
+	exit(2)
+}
diff --git a/libgo/go/runtime/signal_mips64x.go b/libgo/go/runtime/signal_mips64x.go
index 77c27148e86..4dbeb42fe5c 100644
--- a/libgo/go/runtime/signal_mips64x.go
+++ b/libgo/go/runtime/signal_mips64x.go
@@ -88,7 +88,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 		c.set_sp(sp)
 		*(*uint64)(unsafe.Pointer(uintptr(sp))) = c.link()
 
-		pc := uintptr(gp.sigpc)
+		pc := gp.sigpc
 
 		// If we don't recognize the PC as code
 		// but we do recognize the link register as code,
diff --git a/libgo/go/runtime/signal_sigtramp.go b/libgo/go/runtime/signal_sigtramp.go
index 00ab03846e1..dbbbcd0392b 100644
--- a/libgo/go/runtime/signal_sigtramp.go
+++ b/libgo/go/runtime/signal_sigtramp.go
@@ -18,7 +18,15 @@ func sigtrampgo(sig uint32, info *siginfo, ctx unsafe.Pointer) {
 	}
 	g := getg()
 	if g == nil {
-		badsignal(uintptr(sig))
+		if sig == _SIGPROF {
+			// Ignore profiling signals that arrive on
+			// non-Go threads. On some systems they will
+			// be handled directly by the signal handler,
+			// by calling sigprofNonGo, in which case we won't
+			// get here anyhow.
+			return
+		}
+		badsignal(uintptr(sig), &sigctxt{info, ctx})
 		return
 	}
 
@@ -29,12 +37,12 @@ func sigtrampgo(sig uint32, info *siginfo, ctx unsafe.Pointer) {
 		sigaltstack(nil, &st)
 		if st.ss_flags&_SS_DISABLE != 0 {
 			setg(nil)
-			cgocallback(unsafe.Pointer(funcPC(noSignalStack)), noescape(unsafe.Pointer(&sig)), unsafe.Sizeof(sig))
+			cgocallback(unsafe.Pointer(funcPC(noSignalStack)), noescape(unsafe.Pointer(&sig)), unsafe.Sizeof(sig), 0)
 		}
 		stsp := uintptr(unsafe.Pointer(st.ss_sp))
 		if sp < stsp || sp >= stsp+st.ss_size {
 			setg(nil)
-			cgocallback(unsafe.Pointer(funcPC(sigNotOnStack)), noescape(unsafe.Pointer(&sig)), unsafe.Sizeof(sig))
+			cgocallback(unsafe.Pointer(funcPC(sigNotOnStack)), noescape(unsafe.Pointer(&sig)), unsafe.Sizeof(sig), 0)
 		}
 		g.m.gsignal.stack.lo = stsp
 		g.m.gsignal.stack.hi = stsp + st.ss_size
diff --git a/libgo/go/runtime/sigtab_linux_generic.go b/libgo/go/runtime/sigtab_linux_generic.go
index 32c40c4768e..ea36bf36452 100644
--- a/libgo/go/runtime/sigtab_linux_generic.go
+++ b/libgo/go/runtime/sigtab_linux_generic.go
@@ -45,7 +45,7 @@ var sigtable = [...]sigTabT{
 	/* 28 */ {_SigNotify, "SIGWINCH: window size change"},
 	/* 29 */ {_SigNotify, "SIGIO: i/o now possible"},
 	/* 30 */ {_SigNotify, "SIGPWR: power failure restart"},
-	/* 31 */ {_SigNotify, "SIGSYS: bad system call"},
+	/* 31 */ {_SigThrow, "SIGSYS: bad system call"},
 	/* 32 */ {_SigSetStack + _SigUnblock, "signal 32"}, /* SIGCANCEL; see issue 6997 */
 	/* 33 */ {_SigSetStack + _SigUnblock, "signal 33"}, /* SIGSETXID; see issues 3871, 9400, 12498 */
 	/* 34 */ {_SigNotify, "signal 34"},
diff --git a/libgo/go/runtime/sigtab_linux_mips64x.go b/libgo/go/runtime/sigtab_linux_mips64x.go
index dbd50f7b1f6..201fe3deeb7 100644
--- a/libgo/go/runtime/sigtab_linux_mips64x.go
+++ b/libgo/go/runtime/sigtab_linux_mips64x.go
@@ -25,7 +25,7 @@ var sigtable = [...]sigTabT{
 	/* 9 */ {0, "SIGKILL: kill"},
 	/* 10 */ {_SigPanic + _SigUnblock, "SIGBUS: bus error"},
 	/* 11 */ {_SigPanic + _SigUnblock, "SIGSEGV: segmentation violation"},
-	/* 12 */ {_SigNotify, "SIGSYS: bad system call"},
+	/* 12 */ {_SigThrow, "SIGSYS: bad system call"},
 	/* 13 */ {_SigNotify, "SIGPIPE: write to broken pipe"},
 	/* 14 */ {_SigNotify, "SIGALRM: alarm clock"},
 	/* 15 */ {_SigNotify + _SigKill, "SIGTERM: termination"},
diff --git a/libgo/go/runtime/stack.go b/libgo/go/runtime/stack.go
index 81059965d96..8398a101fd8 100644
--- a/libgo/go/runtime/stack.go
+++ b/libgo/go/runtime/stack.go
@@ -93,7 +93,7 @@ const (
 	_StackGuard = 720*sys.StackGuardMultiplier + _StackSystem
 
 	// After a stack split check the SP is allowed to be this
-	// many bytes below the stack guard.  This saves an instruction
+	// many bytes below the stack guard. This saves an instruction
 	// in the checking sequence for tiny frames.
 	_StackSmall = 128
 
@@ -127,7 +127,6 @@ const (
 
 const (
 	uintptrMask = 1<<(8*sys.PtrSize) - 1
-	poisonStack = uintptrMask & 0x6868686868686868
 
 	// Goroutine preemption request.
 	// Stored into g->stackguard0 to cause split stack check failure.
@@ -155,9 +154,6 @@ var stackLarge struct {
 	free [_MHeapMap_Bits]mSpanList // free lists by log_2(s.npages)
 }
 
-// Cached value of haveexperiment("framepointer")
-var framepointer_enabled bool
-
 func stackinit() {
 	if _StackCacheSize&_PageMask != 0 {
 		throw("cache size must be a multiple of page size")
@@ -180,57 +176,57 @@ func stacklog2(n uintptr) int {
 	return log2
 }
 
-// Allocates a stack from the free pool.  Must be called with
+// Allocates a stack from the free pool. Must be called with
 // stackpoolmu held.
 func stackpoolalloc(order uint8) gclinkptr {
 	list := &stackpool[order]
 	s := list.first
 	if s == nil {
-		// no free stacks.  Allocate another span worth.
+		// no free stacks. Allocate another span worth.
 		s = mheap_.allocStack(_StackCacheSize >> _PageShift)
 		if s == nil {
 			throw("out of memory")
 		}
-		if s.ref != 0 {
-			throw("bad ref")
+		if s.allocCount != 0 {
+			throw("bad allocCount")
 		}
-		if s.freelist.ptr() != nil {
-			throw("bad freelist")
+		if s.stackfreelist.ptr() != nil {
+			throw("bad stackfreelist")
 		}
 		for i := uintptr(0); i < _StackCacheSize; i += _FixedStack << order {
-			x := gclinkptr(uintptr(s.start)<<_PageShift + i)
-			x.ptr().next = s.freelist
-			s.freelist = x
+			x := gclinkptr(s.base() + i)
+			x.ptr().next = s.stackfreelist
+			s.stackfreelist = x
 		}
 		list.insert(s)
 	}
-	x := s.freelist
+	x := s.stackfreelist
 	if x.ptr() == nil {
 		throw("span has no free stacks")
 	}
-	s.freelist = x.ptr().next
-	s.ref++
-	if s.freelist.ptr() == nil {
+	s.stackfreelist = x.ptr().next
+	s.allocCount++
+	if s.stackfreelist.ptr() == nil {
 		// all stacks in s are allocated.
 		list.remove(s)
 	}
 	return x
 }
 
-// Adds stack x to the free pool.  Must be called with stackpoolmu held.
+// Adds stack x to the free pool. Must be called with stackpoolmu held.
 func stackpoolfree(x gclinkptr, order uint8) {
 	s := mheap_.lookup(unsafe.Pointer(x))
 	if s.state != _MSpanStack {
 		throw("freeing stack not in a stack span")
 	}
-	if s.freelist.ptr() == nil {
+	if s.stackfreelist.ptr() == nil {
 		// s will now have a free stack
 		stackpool[order].insert(s)
 	}
-	x.ptr().next = s.freelist
-	s.freelist = x
-	s.ref--
-	if gcphase == _GCoff && s.ref == 0 {
+	x.ptr().next = s.stackfreelist
+	s.stackfreelist = x
+	s.allocCount--
+	if gcphase == _GCoff && s.allocCount == 0 {
 		// Span is completely free. Return it to the heap
 		// immediately if we're sweeping.
 		//
@@ -247,13 +243,15 @@ func stackpoolfree(x gclinkptr, order uint8) {
 		//
 		// By not freeing, we prevent step #4 until GC is done.
 		stackpool[order].remove(s)
-		s.freelist = 0
+		s.stackfreelist = 0
 		mheap_.freeStack(s)
 	}
 }
 
 // stackcacherefill/stackcacherelease implement a global pool of stack segments.
 // The pool is required to prevent unlimited growth of per-thread caches.
+//
+//go:systemstack
 func stackcacherefill(c *mcache, order uint8) {
 	if stackDebug >= 1 {
 		print("stackcacherefill order=", order, "\n")
@@ -275,6 +273,7 @@ func stackcacherefill(c *mcache, order uint8) {
 	c.stackcache[order].size = size
 }
 
+//go:systemstack
 func stackcacherelease(c *mcache, order uint8) {
 	if stackDebug >= 1 {
 		print("stackcacherelease order=", order, "\n")
@@ -293,6 +292,7 @@ func stackcacherelease(c *mcache, order uint8) {
 	c.stackcache[order].size = size
 }
 
+//go:systemstack
 func stackcache_clear(c *mcache) {
 	if stackDebug >= 1 {
 		print("stackcache clear\n")
@@ -311,6 +311,12 @@ func stackcache_clear(c *mcache) {
 	unlock(&stackpoolmu)
 }
 
+// stackalloc allocates an n byte stack.
+//
+// stackalloc must run on the system stack because it uses per-P
+// resources and must not split the stack.
+//
+//go:systemstack
 func stackalloc(n uint32) (stack, []stkbar) {
 	// Stackalloc must be called on scheduler stack, so that we
 	// never try to grow the stack during the code that stackalloc runs.
@@ -391,7 +397,7 @@ func stackalloc(n uint32) (stack, []stkbar) {
 				throw("out of memory")
 			}
 		}
-		v = unsafe.Pointer(s.start << _PageShift)
+		v = unsafe.Pointer(s.base())
 	}
 
 	if raceenabled {
@@ -408,6 +414,12 @@ func stackalloc(n uint32) (stack, []stkbar) {
 	return stack{uintptr(v), uintptr(v) + top}, *(*[]stkbar)(unsafe.Pointer(&stkbarSlice))
 }
 
+// stackfree frees an n byte stack allocation at stk.
+//
+// stackfree must run on the system stack because it uses per-P
+// resources and must not split the stack.
+//
+//go:systemstack
 func stackfree(stk stack, n uintptr) {
 	gp := getg()
 	v := unsafe.Pointer(stk.lo)
@@ -456,7 +468,7 @@ func stackfree(stk stack, n uintptr) {
 	} else {
 		s := mheap_.lookup(v)
 		if s.state != _MSpanStack {
-			println(hex(s.start<<_PageShift), v)
+			println(hex(s.base()), v)
 			throw("bad span state")
 		}
 		if gcphase == _GCoff {
@@ -516,20 +528,23 @@ type adjustinfo struct {
 	old   stack
 	delta uintptr // ptr distance from old to new stack (newbase - oldbase)
 	cache pcvalueCache
+
+	// sghi is the highest sudog.elem on the stack.
+	sghi uintptr
 }
 
 // Adjustpointer checks whether *vpp is in the old stack described by adjinfo.
 // If so, it rewrites *vpp to point into the new stack.
 func adjustpointer(adjinfo *adjustinfo, vpp unsafe.Pointer) {
-	pp := (*unsafe.Pointer)(vpp)
+	pp := (*uintptr)(vpp)
 	p := *pp
 	if stackDebug >= 4 {
-		print("        ", pp, ":", p, "\n")
+		print("        ", pp, ":", hex(p), "\n")
 	}
-	if adjinfo.old.lo <= uintptr(p) && uintptr(p) < adjinfo.old.hi {
-		*pp = add(p, adjinfo.delta)
+	if adjinfo.old.lo <= p && p < adjinfo.old.hi {
+		*pp = p + adjinfo.delta
 		if stackDebug >= 3 {
-			print("        adjust ptr ", pp, ":", p, " -> ", *pp, "\n")
+			print("        adjust ptr ", pp, ":", hex(p), " -> ", hex(*pp), "\n")
 		}
 	}
 }
@@ -563,15 +578,22 @@ func adjustpointers(scanp unsafe.Pointer, cbv *bitvector, adjinfo *adjustinfo, f
 	minp := adjinfo.old.lo
 	maxp := adjinfo.old.hi
 	delta := adjinfo.delta
-	num := uintptr(bv.n)
+	num := bv.n
+	// If this frame might contain channel receive slots, use CAS
+	// to adjust pointers. If the slot hasn't been received into
+	// yet, it may contain stack pointers and a concurrent send
+	// could race with adjusting those pointers. (The sent value
+	// itself can never contain stack pointers.)
+	useCAS := uintptr(scanp) < adjinfo.sghi
 	for i := uintptr(0); i < num; i++ {
 		if stackDebug >= 4 {
 			print("        ", add(scanp, i*sys.PtrSize), ":", ptrnames[ptrbit(&bv, i)], ":", hex(*(*uintptr)(add(scanp, i*sys.PtrSize))), " # ", i, " ", bv.bytedata[i/8], "\n")
 		}
 		if ptrbit(&bv, i) == 1 {
 			pp := (*uintptr)(add(scanp, i*sys.PtrSize))
+		retry:
 			p := *pp
-			if f != nil && 0 < p && p < _PageSize && debug.invalidptr != 0 || p == poisonStack {
+			if f != nil && 0 < p && p < _PageSize && debug.invalidptr != 0 {
 				// Looks like a junk value in a pointer slot.
 				// Live analysis wrong?
 				getg().m.traceback = 2
@@ -582,7 +604,14 @@ func adjustpointers(scanp unsafe.Pointer, cbv *bitvector, adjinfo *adjustinfo, f
 				if stackDebug >= 3 {
 					print("adjust ptr ", p, " ", funcname(f), "\n")
 				}
-				*pp = p + delta
+				if useCAS {
+					ppu := (*unsafe.Pointer)(unsafe.Pointer(pp))
+					if !atomic.Casp1(ppu, unsafe.Pointer(p), unsafe.Pointer(p+delta)) {
+						goto retry
+					}
+				} else {
+					*pp = p + delta
+				}
 			}
 		}
 	}
@@ -617,8 +646,8 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 	// Adjust local variables if stack frame has been allocated.
 	size := frame.varp - frame.sp
 	var minsize uintptr
-	switch sys.TheChar {
-	case '7':
+	switch sys.ArchFamily {
+	case sys.ARM64:
 		minsize = sys.SpAlign
 	default:
 		minsize = sys.MinFrameSize
@@ -645,7 +674,7 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 	}
 
 	// Adjust saved base pointer if there is one.
-	if sys.TheChar == '6' && frame.argp-frame.varp == 2*sys.RegSize {
+	if sys.ArchFamily == sys.AMD64 && frame.argp-frame.varp == 2*sys.RegSize {
 		if !framepointer_enabled {
 			print("runtime: found space for saved base pointer, but no framepointer experiment\n")
 			print("argp=", hex(frame.argp), " varp=", hex(frame.varp), "\n")
@@ -665,7 +694,7 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
 		} else {
 			stackmap := (*stackmap)(funcdata(f, _FUNCDATA_ArgsPointerMaps))
 			if stackmap == nil || stackmap.n <= 0 {
-				print("runtime: frame ", funcname(f), " untyped args ", frame.argp, "+", uintptr(frame.arglen), "\n")
+				print("runtime: frame ", funcname(f), " untyped args ", frame.argp, "+", frame.arglen, "\n")
 				throw("missing stackmap")
 			}
 			if pcdata < 0 || pcdata >= stackmap.n {
@@ -727,9 +756,76 @@ func fillstack(stk stack, b byte) {
 	}
 }
 
+func findsghi(gp *g, stk stack) uintptr {
+	var sghi uintptr
+	for sg := gp.waiting; sg != nil; sg = sg.waitlink {
+		p := uintptr(sg.elem) + uintptr(sg.c.elemsize)
+		if stk.lo <= p && p < stk.hi && p > sghi {
+			sghi = p
+		}
+		p = uintptr(unsafe.Pointer(sg.selectdone)) + unsafe.Sizeof(sg.selectdone)
+		if stk.lo <= p && p < stk.hi && p > sghi {
+			sghi = p
+		}
+	}
+	return sghi
+}
+
+// syncadjustsudogs adjusts gp's sudogs and copies the part of gp's
+// stack they refer to while synchronizing with concurrent channel
+// operations. It returns the number of bytes of stack copied.
+func syncadjustsudogs(gp *g, used uintptr, adjinfo *adjustinfo) uintptr {
+	if gp.waiting == nil {
+		return 0
+	}
+
+	// Lock channels to prevent concurrent send/receive.
+	// It's important that we *only* do this for async
+	// copystack; otherwise, gp may be in the middle of
+	// putting itself on wait queues and this would
+	// self-deadlock.
+	var lastc *hchan
+	for sg := gp.waiting; sg != nil; sg = sg.waitlink {
+		if sg.c != lastc {
+			lock(&sg.c.lock)
+		}
+		lastc = sg.c
+	}
+
+	// Adjust sudogs.
+	adjustsudogs(gp, adjinfo)
+
+	// Copy the part of the stack the sudogs point in to
+	// while holding the lock to prevent races on
+	// send/receive slots.
+	var sgsize uintptr
+	if adjinfo.sghi != 0 {
+		oldBot := adjinfo.old.hi - used
+		newBot := oldBot + adjinfo.delta
+		sgsize = adjinfo.sghi - oldBot
+		memmove(unsafe.Pointer(newBot), unsafe.Pointer(oldBot), sgsize)
+	}
+
+	// Unlock channels.
+	lastc = nil
+	for sg := gp.waiting; sg != nil; sg = sg.waitlink {
+		if sg.c != lastc {
+			unlock(&sg.c.lock)
+		}
+		lastc = sg.c
+	}
+
+	return sgsize
+}
+
 // Copies gp's stack to a new stack of a different size.
 // Caller must have changed gp status to Gcopystack.
-func copystack(gp *g, newsize uintptr) {
+//
+// If sync is true, this is a self-triggered stack growth and, in
+// particular, no other G may be writing to gp's stack (e.g., via a
+// channel operation). If sync is false, copystack protects against
+// concurrent channel operations.
+func copystack(gp *g, newsize uintptr, sync bool) {
 	if gp.syscallsp != 0 {
 		throw("stack growth not allowed in system call")
 	}
@@ -748,28 +844,46 @@ func copystack(gp *g, newsize uintptr) {
 		print("copystack gp=", gp, " [", hex(old.lo), " ", hex(old.hi-used), " ", hex(old.hi), "]/", gp.stackAlloc, " -> [", hex(new.lo), " ", hex(new.hi-used), " ", hex(new.hi), "]/", newsize, "\n")
 	}
 
-	// Disallow sigprof scans of this stack and block if there's
-	// one in progress.
-	gcLockStackBarriers(gp)
-
-	// adjust pointers in the to-be-copied frames
+	// Compute adjustment.
 	var adjinfo adjustinfo
 	adjinfo.old = old
 	adjinfo.delta = new.hi - old.hi
-	gentraceback(^uintptr(0), ^uintptr(0), 0, gp, 0, nil, 0x7fffffff, adjustframe, noescape(unsafe.Pointer(&adjinfo)), 0)
 
-	// adjust other miscellaneous things that have pointers into stacks.
+	// Adjust sudogs, synchronizing with channel ops if necessary.
+	ncopy := used
+	if sync {
+		adjustsudogs(gp, &adjinfo)
+	} else {
+		// sudogs can point in to the stack. During concurrent
+		// shrinking, these areas may be written to. Find the
+		// highest such pointer so we can handle everything
+		// there and below carefully. (This shouldn't be far
+		// from the bottom of the stack, so there's little
+		// cost in handling everything below it carefully.)
+		adjinfo.sghi = findsghi(gp, old)
+
+		// Synchronize with channel ops and copy the part of
+		// the stack they may interact with.
+		ncopy -= syncadjustsudogs(gp, used, &adjinfo)
+	}
+
+	// Copy the stack (or the rest of it) to the new location
+	memmove(unsafe.Pointer(new.hi-ncopy), unsafe.Pointer(old.hi-ncopy), ncopy)
+
+	// Disallow sigprof scans of this stack and block if there's
+	// one in progress.
+	gcLockStackBarriers(gp)
+
+	// Adjust remaining structures that have pointers into stacks.
+	// We have to do most of these before we traceback the new
+	// stack because gentraceback uses them.
 	adjustctxt(gp, &adjinfo)
 	adjustdefers(gp, &adjinfo)
 	adjustpanics(gp, &adjinfo)
-	adjustsudogs(gp, &adjinfo)
 	adjuststkbar(gp, &adjinfo)
-
-	// copy the stack to the new location
-	if stackPoisonCopy != 0 {
-		fillstack(new, 0xfb)
+	if adjinfo.sghi != 0 {
+		adjinfo.sghi += adjinfo.delta
 	}
-	memmove(unsafe.Pointer(new.hi-used), unsafe.Pointer(old.hi-used), used)
 
 	// copy old stack barriers to new stack barrier array
 	newstkbar = newstkbar[:len(gp.stkbar)]
@@ -784,6 +898,9 @@ func copystack(gp *g, newsize uintptr) {
 	gp.stkbar = newstkbar
 	gp.stktopsp += adjinfo.delta
 
+	// Adjust pointers in the new stack.
+	gentraceback(^uintptr(0), ^uintptr(0), 0, gp, 0, nil, 0x7fffffff, adjustframe, noescape(unsafe.Pointer(&adjinfo)), 0)
+
 	gcUnlockStackBarriers(gp)
 
 	// free old stack
@@ -868,16 +985,11 @@ func newstack() {
 		}
 	}
 
-	// The goroutine must be executing in order to call newstack,
-	// so it must be Grunning (or Gscanrunning).
-	casgstatus(gp, _Grunning, _Gwaiting)
-	gp.waitreason = "stack growth"
-
 	if gp.stack.lo == 0 {
 		throw("missing stack in newstack")
 	}
 	sp := gp.sched.sp
-	if sys.TheChar == '6' || sys.TheChar == '8' {
+	if sys.ArchFamily == sys.AMD64 || sys.ArchFamily == sys.I386 {
 		// The call to morestack cost a word.
 		sp -= sys.PtrSize
 	}
@@ -907,6 +1019,8 @@ func newstack() {
 		if thisg.m.p == 0 && thisg.m.locks == 0 {
 			throw("runtime: g is running but p is not")
 		}
+		// Synchronize with scang.
+		casgstatus(gp, _Grunning, _Gwaiting)
 		if gp.preemptscan {
 			for !castogscanstatus(gp, _Gwaiting, _Gscanwaiting) {
 				// Likely to be racing with the GC as
@@ -916,12 +1030,19 @@ func newstack() {
 				// return.
 			}
 			if !gp.gcscandone {
-				scanstack(gp)
+				// gcw is safe because we're on the
+				// system stack.
+				gcw := &gp.m.p.ptr().gcw
+				scanstack(gp, gcw)
+				if gcBlackenPromptly {
+					gcw.dispose()
+				}
 				gp.gcscandone = true
 			}
 			gp.preemptscan = false
 			gp.preempt = false
 			casfrom_Gscanstatus(gp, _Gscanwaiting, _Gwaiting)
+			// This clears gcscanvalid.
 			casgstatus(gp, _Gwaiting, _Grunning)
 			gp.stackguard0 = gp.stack.lo + _StackGuard
 			gogo(&gp.sched) // never return
@@ -940,11 +1061,13 @@ func newstack() {
 		throw("stack overflow")
 	}
 
-	casgstatus(gp, _Gwaiting, _Gcopystack)
+	// The goroutine must be executing in order to call newstack,
+	// so it must be Grunning (or Gscanrunning).
+	casgstatus(gp, _Grunning, _Gcopystack)
 
 	// The concurrent GC will not scan the stack while we are doing the copy since
 	// the gp is in a Gcopystack status.
-	copystack(gp, uintptr(newsize))
+	copystack(gp, uintptr(newsize), true)
 	if stackDebug >= 1 {
 		print("stack grow done\n")
 	}
@@ -971,8 +1094,10 @@ func gostartcallfn(gobuf *gobuf, fv *funcval) {
 
 // Maybe shrink the stack being used by gp.
 // Called at garbage collection time.
+// gp must be stopped, but the world need not be.
 func shrinkstack(gp *g) {
-	if readgstatus(gp) == _Gdead {
+	gstatus := readgstatus(gp)
+	if gstatus&^_Gscan == _Gdead {
 		if gp.stack.lo != 0 {
 			// Free whole stack - it will get reallocated
 			// if G is used again.
@@ -987,6 +1112,9 @@ func shrinkstack(gp *g) {
 	if gp.stack.lo == 0 {
 		throw("missing stack in shrinkstack")
 	}
+	if gstatus&_Gscan == 0 {
+		throw("bad status in shrinkstack")
+	}
 
 	if debug.gcshrinkstackoff > 0 {
 		return
@@ -1022,9 +1150,7 @@ func shrinkstack(gp *g) {
 		print("shrinking stack ", oldsize, "->", newsize, "\n")
 	}
 
-	oldstatus := casgcopystack(gp)
-	copystack(gp, newsize)
-	casgstatus(gp, _Gcopystack, oldstatus)
+	copystack(gp, newsize, false)
 }
 
 // freeStackSpans frees unused stack spans at the end of GC.
@@ -1036,9 +1162,9 @@ func freeStackSpans() {
 		list := &stackpool[order]
 		for s := list.first; s != nil; {
 			next := s.next
-			if s.ref == 0 {
+			if s.allocCount == 0 {
 				list.remove(s)
-				s.freelist = 0
+				s.stackfreelist = 0
 				mheap_.freeStack(s)
 			}
 			s = next
diff --git a/libgo/go/runtime/string_test.go b/libgo/go/runtime/string_test.go
index 64abd57d28c..f9411c00161 100644
--- a/libgo/go/runtime/string_test.go
+++ b/libgo/go/runtime/string_test.go
@@ -9,6 +9,10 @@ import (
 	"testing"
 )
 
+// Strings and slices that don't escape and fit into tmpBuf are stack allocated,
+// which defeats using AllocsPerRun to test other optimizations.
+const sizeNoStack = 100
+
 func BenchmarkCompareStringEqual(b *testing.B) {
 	bytes := []byte("Hello Gophers!")
 	s1, s2 := string(bytes), string(bytes)
@@ -101,6 +105,17 @@ func BenchmarkRuneIterate2(b *testing.B) {
 	}
 }
 
+func BenchmarkArrayEqual(b *testing.B) {
+	a1 := [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
+	a2 := [16]byte{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		if a1 != a2 {
+			b.Fatal("not equal")
+		}
+	}
+}
+
 /*
 func TestStringW(t *testing.T) {
 	strings := []string{
@@ -150,7 +165,7 @@ func TestGostringnocopy(t *testing.T) {
 */
 
 func TestCompareTempString(t *testing.T) {
-	s := "foo"
+	s := strings.Repeat("x", sizeNoStack)
 	b := []byte(s)
 	n := testing.AllocsPerRun(1000, func() {
 		if string(b) != s {
@@ -161,7 +176,8 @@ func TestCompareTempString(t *testing.T) {
 			t.Fatalf("strings are not equal: '%v' and '%v'", string(b), s)
 		}
 	})
-	if n != 0 {
+	// was n != 0, changed for gccgo.
+	if n > 2 {
 		t.Fatalf("want 0 allocs, got %v", n)
 	}
 }
@@ -213,7 +229,7 @@ func TestIntStringAllocs(t *testing.T) {
 }
 
 func TestRangeStringCast(t *testing.T) {
-	s := "abc"
+	s := strings.Repeat("x", sizeNoStack)
 	n := testing.AllocsPerRun(1000, func() {
 		for i, c := range []byte(s) {
 			if c != s[i] {
@@ -221,22 +237,41 @@ func TestRangeStringCast(t *testing.T) {
 			}
 		}
 	})
-	if n != 0 {
+	// was n != 0, changed for gccgo.
+	if n > 1 {
 		t.Fatalf("want 0 allocs, got %v", n)
 	}
 }
 
+func isZeroed(b []byte) bool {
+	for _, x := range b {
+		if x != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+func isZeroedR(r []rune) bool {
+	for _, x := range r {
+		if x != 0 {
+			return false
+		}
+	}
+	return true
+}
+
 func TestString2Slice(t *testing.T) {
 	// Make sure we don't return slices that expose
 	// an unzeroed section of stack-allocated temp buf
-	// between len and cap.  See issue 14232.
+	// between len and cap. See issue 14232.
 	s := "foož"
 	b := ([]byte)(s)
-	if cap(b) != 5 {
-		t.Errorf("want cap of 5, got %d", cap(b))
+	if !isZeroed(b[len(b):cap(b)]) {
+		t.Errorf("extra bytes not zeroed")
 	}
 	r := ([]rune)(s)
-	if cap(r) != 4 {
-		t.Errorf("want cap of 4, got %d", cap(r))
+	if !isZeroedR(r[len(r):cap(r)]) {
+		t.Errorf("extra runes not zeroed")
 	}
 }
diff --git a/libgo/go/runtime/symtab.go b/libgo/go/runtime/symtab.go
new file mode 100644
index 00000000000..7b76f11f3a6
--- /dev/null
+++ b/libgo/go/runtime/symtab.go
@@ -0,0 +1,129 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+// Frames may be used to get function/file/line information for a
+// slice of PC values returned by Callers.
+type Frames struct {
+	callers []uintptr
+
+	// The last PC we saw.
+	last uintptr
+
+	// The number of times we've seen last.
+	lastCount int
+}
+
+// Frame is the information returned by Frames for each call frame.
+type Frame struct {
+	// Program counter for this frame; multiple frames may have
+	// the same PC value.
+	PC uintptr
+
+	// Func for this frame; may be nil for non-Go code or fully
+	// inlined functions.
+	Func *Func
+
+	// Function name, file name, and line number for this call frame.
+	// May be the empty string or zero if not known.
+	// If Func is not nil then Function == Func.Name().
+	Function string
+	File     string
+	Line     int
+
+	// Entry point for the function; may be zero if not known.
+	// If Func is not nil then Entry == Func.Entry().
+	Entry uintptr
+}
+
+// CallersFrames takes a slice of PC values returned by Callers and
+// prepares to return function/file/line information.
+// Do not change the slice until you are done with the Frames.
+func CallersFrames(callers []uintptr) *Frames {
+	return &Frames{callers: callers}
+}
+
+// Next returns frame information for the next caller.
+// If more is false, there are no more callers (the Frame value is valid).
+func (ci *Frames) Next() (frame Frame, more bool) {
+	if len(ci.callers) == 0 {
+		return Frame{}, false
+	}
+
+	pc := ci.callers[0]
+	ci.callers = ci.callers[1:]
+
+	i := 0
+	if pc == ci.last {
+		ci.lastCount++
+		i = ci.lastCount
+	} else {
+		ci.last = pc
+		ci.lastCount = 0
+	}
+	more = len(ci.callers) > 0
+
+	f, file, line := funcframe(pc, i)
+	if f == nil {
+		return Frame{}, more
+	}
+
+	entry := f.Entry()
+	xpc := pc
+	if xpc > entry {
+		xpc--
+	}
+
+	function := f.Name()
+
+	frame = Frame{
+		PC:       xpc,
+		Func:     f,
+		Function: function,
+		File:     file,
+		Line:     line,
+		Entry:    entry,
+	}
+
+	return frame, more
+}
+
+// NOTE: Func does not expose the actual unexported fields, because we return *Func
+// values to users, and we want to keep them from being able to overwrite the data
+// with (say) *f = Func{}.
+// All code operating on a *Func must call raw to get the *_func instead.
+
+// A Func represents a Go function in the running binary.
+type Func struct {
+	opaque struct{} // unexported field to disallow conversions
+}
+
+// FuncForPC returns a *Func describing the function that contains the
+// given program counter address, or else nil.
+func FuncForPC(pc uintptr) *Func
+
+// Name returns the name of the function.
+func (f *Func) Name() string {
+	return funcname_go(f)
+}
+
+// Entry returns the entry address of the function.
+func (f *Func) Entry() uintptr {
+	return funcentry_go(f)
+}
+
+// FileLine returns the file name and line number of the
+// source code corresponding to the program counter pc.
+// The result will not be accurate if pc is not a program
+// counter within f.
+func (f *Func) FileLine(pc uintptr) (file string, line int) {
+	return funcline_go(f, pc)
+}
+
+// implemented in symtab.c
+func funcline_go(*Func, uintptr) (string, int)
+func funcname_go(*Func) string
+func funcentry_go(*Func) uintptr
+func funcframe(uintptr, int) (*Func, string, int)
diff --git a/libgo/go/runtime/sys_s390x.go b/libgo/go/runtime/sys_s390x.go
new file mode 100644
index 00000000000..2aa81e75c06
--- /dev/null
+++ b/libgo/go/runtime/sys_s390x.go
@@ -0,0 +1,45 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import "unsafe"
+
+// adjust Gobuf as if it executed a call to fn with context ctxt
+// and then did an immediate Gosave.
+func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
+	if buf.lr != 0 {
+		throw("invalid use of gostartcall")
+	}
+	buf.lr = buf.pc
+	buf.pc = uintptr(fn)
+	buf.ctxt = ctxt
+}
+
+// Called to rewind context saved during morestack back to beginning of function.
+// To help us, the linker emits a jmp back to the beginning right after the
+// call to morestack. We just have to decode and apply that jump.
+func rewindmorestack(buf *gobuf) {
+	var inst uint64
+	if buf.pc&1 == 0 && buf.pc != 0 {
+		inst = *(*uint64)(unsafe.Pointer(buf.pc))
+		switch inst >> 48 {
+		case 0xa7f4: // BRC (branch relative on condition) instruction.
+			inst >>= 32
+			inst &= 0xFFFF
+			offset := int64(int16(inst))
+			offset <<= 1
+			buf.pc += uintptr(offset)
+			return
+		case 0xc0f4: // BRCL (branch relative on condition long) instruction.
+			inst >>= 16
+			inst = inst & 0xFFFFFFFF
+			inst = (inst << 1) & 0xFFFFFFFF
+			buf.pc += uintptr(int32(inst))
+			return
+		}
+	}
+	print("runtime: pc=", hex(buf.pc), " ", hex(inst), "\n")
+	throw("runtime: misuse of rewindmorestack")
+}
diff --git a/libgo/go/runtime/testdata/testprog/crash.go b/libgo/go/runtime/testdata/testprog/crash.go
index 3d7c7c6aabc..4d83132198d 100644
--- a/libgo/go/runtime/testdata/testprog/crash.go
+++ b/libgo/go/runtime/testdata/testprog/crash.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprog/deadlock.go b/libgo/go/runtime/testdata/testprog/deadlock.go
index 73fbf6224df..c938fcfb569 100644
--- a/libgo/go/runtime/testdata/testprog/deadlock.go
+++ b/libgo/go/runtime/testdata/testprog/deadlock.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -30,6 +30,8 @@ func init() {
 	register("PanicAfterGoexit", PanicAfterGoexit)
 	register("RecoveredPanicAfterGoexit", RecoveredPanicAfterGoexit)
 	register("PanicTraceback", PanicTraceback)
+	register("GoschedInPanic", GoschedInPanic)
+	register("SyscallInPanic", SyscallInPanic)
 }
 
 func SimpleDeadlock() {
@@ -152,6 +154,29 @@ func GoexitInPanic() {
 	runtime.Goexit()
 }
 
+type errorThatGosched struct{}
+
+func (errorThatGosched) Error() string {
+	runtime.Gosched()
+	return "errorThatGosched"
+}
+
+func GoschedInPanic() {
+	panic(errorThatGosched{})
+}
+
+type errorThatPrint struct{}
+
+func (errorThatPrint) Error() string {
+	fmt.Println("1")
+	fmt.Println("2")
+	return "3"
+}
+
+func SyscallInPanic() {
+	panic(errorThatPrint{})
+}
+
 func PanicAfterGoexit() {
 	defer func() {
 		panic("hello")
diff --git a/libgo/go/runtime/testdata/testprog/gc.go b/libgo/go/runtime/testdata/testprog/gc.go
index 9bb367c0d15..a0c1f82b56b 100644
--- a/libgo/go/runtime/testdata/testprog/gc.go
+++ b/libgo/go/runtime/testdata/testprog/gc.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -8,11 +8,14 @@ import (
 	"fmt"
 	"os"
 	"runtime"
+	"runtime/debug"
+	"sync/atomic"
 	"time"
 )
 
 func init() {
 	register("GCFairness", GCFairness)
+	register("GCFairness2", GCFairness2)
 	register("GCSys", GCSys)
 }
 
@@ -72,3 +75,35 @@ func GCFairness() {
 	time.Sleep(10 * time.Millisecond)
 	fmt.Println("OK")
 }
+
+func GCFairness2() {
+	// Make sure user code can't exploit the GC's high priority
+	// scheduling to make scheduling of user code unfair. See
+	// issue #15706.
+	runtime.GOMAXPROCS(1)
+	debug.SetGCPercent(1)
+	var count [3]int64
+	var sink [3]interface{}
+	for i := range count {
+		go func(i int) {
+			for {
+				sink[i] = make([]byte, 1024)
+				atomic.AddInt64(&count[i], 1)
+			}
+		}(i)
+	}
+	// Note: If the unfairness is really bad, it may not even get
+	// past the sleep.
+	//
+	// If the scheduling rules change, this may not be enough time
+	// to let all goroutines run, but for now we cycle through
+	// them rapidly.
+	time.Sleep(30 * time.Millisecond)
+	for i := range count {
+		if atomic.LoadInt64(&count[i]) == 0 {
+			fmt.Printf("goroutine %d did not run\n", i)
+			return
+		}
+	}
+	fmt.Println("OK")
+}
diff --git a/libgo/go/runtime/testdata/testprog/main.go b/libgo/go/runtime/testdata/testprog/main.go
index 9c227bbf819..ae491a2a978 100644
--- a/libgo/go/runtime/testdata/testprog/main.go
+++ b/libgo/go/runtime/testdata/testprog/main.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprog/memprof.go b/libgo/go/runtime/testdata/testprog/memprof.go
new file mode 100644
index 00000000000..a22fee61d78
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprog/memprof.go
@@ -0,0 +1,49 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"runtime"
+	"runtime/pprof"
+)
+
+func init() {
+	register("MemProf", MemProf)
+}
+
+var memProfBuf bytes.Buffer
+var memProfStr string
+
+func MemProf() {
+	for i := 0; i < 1000; i++ {
+		fmt.Fprintf(&memProfBuf, "%*d\n", i, i)
+	}
+	memProfStr = memProfBuf.String()
+
+	runtime.GC()
+
+	f, err := ioutil.TempFile("", "memprof")
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	if err := pprof.WriteHeapProfile(f); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	name := f.Name()
+	if err := f.Close(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	fmt.Println(name)
+}
diff --git a/libgo/go/runtime/testdata/testprog/misc.go b/libgo/go/runtime/testdata/testprog/misc.go
index 237680fc87e..7ccd389c944 100644
--- a/libgo/go/runtime/testdata/testprog/misc.go
+++ b/libgo/go/runtime/testdata/testprog/misc.go
@@ -1,4 +1,4 @@
-// Copyright 2016 The Go Authors.  All rights reserved.
+// Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprog/signal.go b/libgo/go/runtime/testdata/testprog/signal.go
index ac2d3e8f6c0..2ccbada57b3 100644
--- a/libgo/go/runtime/testdata/testprog/signal.go
+++ b/libgo/go/runtime/testdata/testprog/signal.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,7 +6,10 @@
 
 package main
 
-import "syscall"
+import (
+	"syscall"
+	"time"
+)
 
 func init() {
 	register("SignalExitStatus", SignalExitStatus)
@@ -14,4 +17,13 @@ func init() {
 
 func SignalExitStatus() {
 	syscall.Kill(syscall.Getpid(), syscall.SIGTERM)
+
+	// Should die immediately, but we've seen flakiness on various
+	// systems (see issue 14063). It's possible that the signal is
+	// being delivered to a different thread and we are returning
+	// and exiting before that thread runs again. Give the program
+	// a little while to die to make sure we pick up the signal
+	// before we return and exit the program. The time here
+	// shouldn't matter--we'll never really sleep this long.
+	time.Sleep(time.Second)
 }
diff --git a/libgo/go/runtime/testdata/testprog/stringconcat.go b/libgo/go/runtime/testdata/testprog/stringconcat.go
index 9dddf1969f4..f233e662065 100644
--- a/libgo/go/runtime/testdata/testprog/stringconcat.go
+++ b/libgo/go/runtime/testdata/testprog/stringconcat.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprog/syscall_windows.go b/libgo/go/runtime/testdata/testprog/syscall_windows.go
index 73165be187b..6e6782e987a 100644
--- a/libgo/go/runtime/testdata/testprog/syscall_windows.go
+++ b/libgo/go/runtime/testdata/testprog/syscall_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/aprof.go b/libgo/go/runtime/testdata/testprogcgo/aprof.go
new file mode 100644
index 00000000000..aabca9e1ebd
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprogcgo/aprof.go
@@ -0,0 +1,53 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Test that SIGPROF received in C code does not crash the process
+// looking for the C code's func pointer.
+
+// The test fails when the function is the first C function.
+// The exported functions are the first C functions, so we use that.
+
+// extern void GoNop();
+import "C"
+
+import (
+	"bytes"
+	"fmt"
+	"runtime/pprof"
+	"time"
+)
+
+func init() {
+	register("CgoCCodeSIGPROF", CgoCCodeSIGPROF)
+}
+
+//export GoNop
+func GoNop() {}
+
+func CgoCCodeSIGPROF() {
+	c := make(chan bool)
+	go func() {
+		<-c
+		start := time.Now()
+		for i := 0; i < 1e7; i++ {
+			if i%1000 == 0 {
+				if time.Since(start) > time.Second {
+					break
+				}
+			}
+			C.GoNop()
+		}
+		c <- true
+	}()
+
+	var buf bytes.Buffer
+	pprof.StartCPUProfile(&buf)
+	c <- true
+	<-c
+	pprof.StopCPUProfile()
+
+	fmt.Println("OK")
+}
diff --git a/libgo/go/runtime/testdata/testprogcgo/callback.go b/libgo/go/runtime/testdata/testprogcgo/callback.go
index 10e248a1590..7d9d68ddd11 100644
--- a/libgo/go/runtime/testdata/testprogcgo/callback.go
+++ b/libgo/go/runtime/testdata/testprogcgo/callback.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/cgo.go b/libgo/go/runtime/testdata/testprogcgo/cgo.go
index cf1af8268ca..870d4efdead 100644
--- a/libgo/go/runtime/testdata/testprogcgo/cgo.go
+++ b/libgo/go/runtime/testdata/testprogcgo/cgo.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -6,17 +6,22 @@ package main
 
 /*
 void foo1(void) {}
+void foo2(void* p) {}
 */
 import "C"
 import (
 	"fmt"
+	"os"
 	"runtime"
+	"strconv"
 	"time"
+	"unsafe"
 )
 
 func init() {
 	register("CgoSignalDeadlock", CgoSignalDeadlock)
 	register("CgoTraceback", CgoTraceback)
+	register("CgoCheckBytes", CgoCheckBytes)
 }
 
 func CgoSignalDeadlock() {
@@ -78,3 +83,18 @@ func CgoTraceback() {
 	runtime.Stack(buf, true)
 	fmt.Printf("OK\n")
 }
+
+func CgoCheckBytes() {
+	try, _ := strconv.Atoi(os.Getenv("GO_CGOCHECKBYTES_TRY"))
+	if try <= 0 {
+		try = 1
+	}
+	b := make([]byte, 1e6*try)
+	start := time.Now()
+	for i := 0; i < 1e3*try; i++ {
+		C.foo2(unsafe.Pointer(&b[0]))
+		if time.Since(start) > time.Second {
+			break
+		}
+	}
+}
diff --git a/libgo/go/runtime/testdata/testprogcgo/crash.go b/libgo/go/runtime/testdata/testprogcgo/crash.go
index 3d7c7c6aabc..4d83132198d 100644
--- a/libgo/go/runtime/testdata/testprogcgo/crash.go
+++ b/libgo/go/runtime/testdata/testprogcgo/crash.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/deadlock.go b/libgo/go/runtime/testdata/testprogcgo/deadlock.go
new file mode 100644
index 00000000000..2cc68a89279
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprogcgo/deadlock.go
@@ -0,0 +1,30 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+/*
+char *geterror() {
+	return "cgo error";
+}
+*/
+import "C"
+import (
+	"fmt"
+)
+
+func init() {
+	register("CgoPanicDeadlock", CgoPanicDeadlock)
+}
+
+type cgoError struct{}
+
+func (cgoError) Error() string {
+	fmt.Print("") // necessary to trigger the deadlock
+	return C.GoString(C.geterror())
+}
+
+func CgoPanicDeadlock() {
+	panic(cgoError{})
+}
diff --git a/libgo/go/runtime/testdata/testprogcgo/dll_windows.go b/libgo/go/runtime/testdata/testprogcgo/dll_windows.go
index a0647ef2125..aed2410a456 100644
--- a/libgo/go/runtime/testdata/testprogcgo/dll_windows.go
+++ b/libgo/go/runtime/testdata/testprogcgo/dll_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/dropm.go b/libgo/go/runtime/testdata/testprogcgo/dropm.go
index 75984ea75f3..9e782f504fe 100644
--- a/libgo/go/runtime/testdata/testprogcgo/dropm.go
+++ b/libgo/go/runtime/testdata/testprogcgo/dropm.go
@@ -1,4 +1,4 @@
-// Copyright 2016 The Go Authors.  All rights reserved.
+// Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/dropm_stub.go b/libgo/go/runtime/testdata/testprogcgo/dropm_stub.go
index 4c3f46ade40..f7f142c1fdd 100644
--- a/libgo/go/runtime/testdata/testprogcgo/dropm_stub.go
+++ b/libgo/go/runtime/testdata/testprogcgo/dropm_stub.go
@@ -1,4 +1,4 @@
-// Copyright 2016 The Go Authors.  All rights reserved.
+// Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/exec.go b/libgo/go/runtime/testdata/testprogcgo/exec.go
index 8dc1d517c6e..2e948401c87 100644
--- a/libgo/go/runtime/testdata/testprogcgo/exec.go
+++ b/libgo/go/runtime/testdata/testprogcgo/exec.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/main.go b/libgo/go/runtime/testdata/testprogcgo/main.go
index 9c227bbf819..ae491a2a978 100644
--- a/libgo/go/runtime/testdata/testprogcgo/main.go
+++ b/libgo/go/runtime/testdata/testprogcgo/main.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/pprof.go b/libgo/go/runtime/testdata/testprogcgo/pprof.go
new file mode 100644
index 00000000000..cb30ec5b250
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprogcgo/pprof.go
@@ -0,0 +1,97 @@
+// Copyright 2016 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// Run a slow C function saving a CPU profile.
+
+/*
+#include <stdint.h>
+
+int salt1;
+int salt2;
+
+void cpuHog() {
+	int foo = salt1;
+	int i;
+
+	for (i = 0; i < 100000; i++) {
+		if (foo > 0) {
+			foo *= foo;
+		} else {
+			foo *= foo + 1;
+		}
+	}
+	salt2 = foo;
+}
+
+static int cpuHogCount;
+
+struct cgoTracebackArg {
+	uintptr_t  context;
+	uintptr_t  sigContext;
+	uintptr_t* buf;
+	uintptr_t  max;
+};
+
+// pprofCgoTraceback is passed to runtime.SetCgoTraceback.
+// For testing purposes it pretends that all CPU hits in C code are in cpuHog.
+void pprofCgoTraceback(void* parg) {
+	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
+	arg->buf[0] = (uintptr_t)(cpuHog) + 0x10;
+	arg->buf[1] = 0;
+	++cpuHogCount;
+}
+
+// getCpuHogCount fetches the number of times we've seen cpuHog in the
+// traceback.
+int getCpuHogCount() {
+	return cpuHogCount;
+}
+*/
+import "C"
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"time"
+	"unsafe"
+)
+
+func init() {
+	register("CgoPprof", CgoPprof)
+}
+
+func CgoPprof() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoTraceback), nil, nil)
+
+	f, err := ioutil.TempFile("", "prof")
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	if err := pprof.StartCPUProfile(f); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	t0 := time.Now()
+	for C.getCpuHogCount() < 2 && time.Since(t0) < time.Second {
+		C.cpuHog()
+	}
+
+	pprof.StopCPUProfile()
+
+	name := f.Name()
+	if err := f.Close(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	fmt.Println(name)
+}
diff --git a/libgo/go/runtime/testdata/testprogcgo/threadpanic.go b/libgo/go/runtime/testdata/testprogcgo/threadpanic.go
index 3c9baba71a2..f9b48a9026d 100644
--- a/libgo/go/runtime/testdata/testprogcgo/threadpanic.go
+++ b/libgo/go/runtime/testdata/testprogcgo/threadpanic.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/threadpprof.go b/libgo/go/runtime/testdata/testprogcgo/threadpprof.go
new file mode 100644
index 00000000000..fdeee6910dd
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprogcgo/threadpprof.go
@@ -0,0 +1,112 @@
+// Copyright 2016 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !plan9,!windows
+
+package main
+
+// Run a slow C function saving a CPU profile.
+
+/*
+#include <stdint.h>
+#include <time.h>
+#include <pthread.h>
+
+int threadSalt1;
+int threadSalt2;
+
+void cpuHogThread() {
+	int foo = threadSalt1;
+	int i;
+
+	for (i = 0; i < 100000; i++) {
+		if (foo > 0) {
+			foo *= foo;
+		} else {
+			foo *= foo + 1;
+		}
+	}
+	threadSalt2 = foo;
+}
+
+static int cpuHogThreadCount;
+
+struct cgoTracebackArg {
+	uintptr_t  context;
+	uintptr_t  sigContext;
+	uintptr_t* buf;
+	uintptr_t  max;
+};
+
+static void *pprofThread(void* p) {
+	time_t start;
+
+	(void)p;
+	start = time(NULL);
+	while (__sync_add_and_fetch(&cpuHogThreadCount, 0) < 2 && time(NULL) - start < 2) {
+		cpuHogThread();
+	}
+}
+
+
+// pprofCgoThreadTraceback is passed to runtime.SetCgoTraceback.
+// For testing purposes it pretends that all CPU hits in C code are in cpuHog.
+void pprofCgoThreadTraceback(void* parg) {
+	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
+	arg->buf[0] = (uintptr_t)(cpuHogThread) + 0x10;
+	arg->buf[1] = 0;
+	__sync_add_and_fetch(&cpuHogThreadCount, 1);
+}
+
+// getCPUHogThreadCount fetches the number of times we've seen cpuHogThread
+// in the traceback.
+int getCPUHogThreadCount() {
+	return __sync_add_and_fetch(&cpuHogThreadCount, 0);
+}
+*/
+import "C"
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"time"
+	"unsafe"
+)
+
+func init() {
+	register("CgoPprofThread", CgoPprofThread)
+}
+
+func CgoPprofThread() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.pprofCgoThreadTraceback), nil, nil)
+
+	f, err := ioutil.TempFile("", "prof")
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	if err := pprof.StartCPUProfile(f); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	t0 := time.Now()
+	for C.getCPUHogThreadCount() < 2 && time.Since(t0) < time.Second {
+		time.Sleep(100 * time.Millisecond)
+	}
+
+	pprof.StopCPUProfile()
+
+	name := f.Name()
+	if err := f.Close(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(2)
+	}
+
+	fmt.Println(name)
+}
diff --git a/libgo/go/runtime/testdata/testprogcgo/threadprof.go b/libgo/go/runtime/testdata/testprogcgo/threadprof.go
index 03e35d2a9e3..a77479dfad1 100644
--- a/libgo/go/runtime/testdata/testprogcgo/threadprof.go
+++ b/libgo/go/runtime/testdata/testprogcgo/threadprof.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprogcgo/traceback.go b/libgo/go/runtime/testdata/testprogcgo/traceback.go
new file mode 100644
index 00000000000..e8b0a04556a
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprogcgo/traceback.go
@@ -0,0 +1,81 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// This program will crash.
+// We want the stack trace to include the C functions.
+// We use a fake traceback, and a symbolizer that dumps a string we recognize.
+
+/*
+#cgo CFLAGS: -g -O0
+
+#include <stdint.h>
+
+char *p;
+
+static int f3() {
+	*p = 0;
+	return 0;
+}
+
+static int f2() {
+	return f3();
+}
+
+static int f1() {
+	return f2();
+}
+
+struct cgoTracebackArg {
+	uintptr_t  context;
+	uintptr_t  sigContext;
+	uintptr_t* buf;
+	uintptr_t  max;
+};
+
+struct cgoSymbolizerArg {
+	uintptr_t   pc;
+	const char* file;
+	uintptr_t   lineno;
+	const char* func;
+	uintptr_t   entry;
+	uintptr_t   more;
+	uintptr_t   data;
+};
+
+void cgoTraceback(void* parg) {
+	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
+	arg->buf[0] = 1;
+	arg->buf[1] = 2;
+	arg->buf[2] = 3;
+	arg->buf[3] = 0;
+}
+
+void cgoSymbolizer(void* parg) {
+	struct cgoSymbolizerArg* arg = (struct cgoSymbolizerArg*)(parg);
+	if (arg->pc != arg->data + 1) {
+		arg->file = "unexpected data";
+	} else {
+		arg->file = "cgo symbolizer";
+	}
+	arg->lineno = arg->data + 1;
+	arg->data++;
+}
+*/
+import "C"
+
+import (
+	"runtime"
+	"unsafe"
+)
+
+func init() {
+	register("CrashTraceback", CrashTraceback)
+}
+
+func CrashTraceback() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.cgoTraceback), nil, unsafe.Pointer(C.cgoSymbolizer))
+	C.f1()
+}
diff --git a/libgo/go/runtime/testdata/testprogcgo/tracebackctxt.go b/libgo/go/runtime/testdata/testprogcgo/tracebackctxt.go
new file mode 100644
index 00000000000..51fa4ad25c3
--- /dev/null
+++ b/libgo/go/runtime/testdata/testprogcgo/tracebackctxt.go
@@ -0,0 +1,107 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// The __attribute__((weak)) used below doesn't seem to work on Windows.
+
+package main
+
+// Test the context argument to SetCgoTraceback.
+// Use fake context, traceback, and symbolizer functions.
+
+/*
+// Defined in tracebackctxt_c.c.
+extern void C1(void);
+extern void C2(void);
+extern void tcContext(void*);
+extern void tcTraceback(void*);
+extern void tcSymbolizer(void*);
+extern int getContextCount(void);
+*/
+import "C"
+
+import (
+	"fmt"
+	"runtime"
+	"unsafe"
+)
+
+func init() {
+	register("TracebackContext", TracebackContext)
+}
+
+var tracebackOK bool
+
+func TracebackContext() {
+	runtime.SetCgoTraceback(0, unsafe.Pointer(C.tcTraceback), unsafe.Pointer(C.tcContext), unsafe.Pointer(C.tcSymbolizer))
+	C.C1()
+	if got := C.getContextCount(); got != 0 {
+		fmt.Printf("at end contextCount == %d, expected 0\n", got)
+		tracebackOK = false
+	}
+	if tracebackOK {
+		fmt.Println("OK")
+	}
+}
+
+//export G1
+func G1() {
+	C.C2()
+}
+
+//export G2
+func G2() {
+	pc := make([]uintptr, 32)
+	n := runtime.Callers(0, pc)
+	cf := runtime.CallersFrames(pc[:n])
+	var frames []runtime.Frame
+	for {
+		frame, more := cf.Next()
+		frames = append(frames, frame)
+		if !more {
+			break
+		}
+	}
+
+	want := []struct {
+		function string
+		line     int
+	}{
+		{"main.G2", 0},
+		{"cFunction", 0x10200},
+		{"cFunction", 0x200},
+		{"cFunction", 0x10201},
+		{"cFunction", 0x201},
+		{"main.G1", 0},
+		{"cFunction", 0x10100},
+		{"cFunction", 0x100},
+		{"main.TracebackContext", 0},
+	}
+
+	ok := true
+	i := 0
+wantLoop:
+	for _, w := range want {
+		for ; i < len(frames); i++ {
+			if w.function == frames[i].Function {
+				if w.line != 0 && w.line != frames[i].Line {
+					fmt.Printf("found function %s at wrong line %#x (expected %#x)\n", w.function, frames[i].Line, w.line)
+					ok = false
+				}
+				i++
+				continue wantLoop
+			}
+		}
+		fmt.Printf("did not find function %s in\n", w.function)
+		for _, f := range frames {
+			fmt.Println(f)
+		}
+		ok = false
+		break
+	}
+	tracebackOK = ok
+	if got := C.getContextCount(); got != 2 {
+		fmt.Printf("at bottom contextCount == %d, expected 2\n", got)
+		tracebackOK = false
+	}
+}
diff --git a/libgo/go/runtime/testdata/testprognet/main.go b/libgo/go/runtime/testdata/testprognet/main.go
index 9c227bbf819..ae491a2a978 100644
--- a/libgo/go/runtime/testdata/testprognet/main.go
+++ b/libgo/go/runtime/testdata/testprognet/main.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprognet/net.go b/libgo/go/runtime/testdata/testprognet/net.go
index c1a7f3f1321..714b10162e3 100644
--- a/libgo/go/runtime/testdata/testprognet/net.go
+++ b/libgo/go/runtime/testdata/testprognet/net.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/testdata/testprognet/signal.go b/libgo/go/runtime/testdata/testprognet/signal.go
index 24d142403e8..a1559fe6163 100644
--- a/libgo/go/runtime/testdata/testprognet/signal.go
+++ b/libgo/go/runtime/testdata/testprognet/signal.go
@@ -1,4 +1,4 @@
-// Copyright 2016 The Go Authors.  All rights reserved.
+// Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/runtime/vlrt.go b/libgo/go/runtime/vlrt.go
index 6370732ca0d..cd37828ae4c 100644
--- a/libgo/go/runtime/vlrt.go
+++ b/libgo/go/runtime/vlrt.go
@@ -1,7 +1,7 @@
 // Inferno's libkern/vlrt-arm.c
 // http://code.google.com/p/inferno-os/source/browse/libkern/vlrt-arm.c
 //
-//         Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
+//         Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
 //         Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
 //         Portions Copyright 2009 The Go Authors. All rights reserved.
 //
@@ -195,7 +195,6 @@ func dodiv(n, d uint64) (q, r uint64) {
 	if GOARCH == "arm" {
 		// arm doesn't have a division instruction, so
 		// slowdodiv is the best that we can do.
-		// TODO: revisit for arm64.
 		return slowdodiv(n, d)
 	}
 
diff --git a/libgo/go/sort/search.go b/libgo/go/sort/search.go
index de8178ff484..b9640a40aff 100644
--- a/libgo/go/sort/search.go
+++ b/libgo/go/sort/search.go
@@ -8,10 +8,10 @@ package sort
 
 // Search uses binary search to find and return the smallest index i
 // in [0, n) at which f(i) is true, assuming that on the range [0, n),
-// f(i) == true implies f(i+1) == true.  That is, Search requires that
+// f(i) == true implies f(i+1) == true. That is, Search requires that
 // f is false for some (possibly empty) prefix of the input range [0, n)
 // and then true for the (possibly empty) remainder; Search returns
-// the first true index.  If there is no such index, Search returns n.
+// the first true index. If there is no such index, Search returns n.
 // (Note that the "not found" return value is not -1 as in, for instance,
 // strings.Index.)
 // Search calls f(i) only for i in the range [0, n).
@@ -85,7 +85,7 @@ func SearchInts(a []int, x int) int {
 }
 
 // SearchFloat64s searches for x in a sorted slice of float64s and returns the index
-// as specified by Search.  The return value is the index to insert x if x is not
+// as specified by Search. The return value is the index to insert x if x is not
 // present (it could be len(a)).
 // The slice must be sorted in ascending order.
 //
@@ -94,7 +94,7 @@ func SearchFloat64s(a []float64, x float64) int {
 }
 
 // SearchStrings searches for x in a sorted slice of strings and returns the index
-// as specified by Search.  The return value is the index to insert x if x is not
+// as specified by Search. The return value is the index to insert x if x is not
 // present (it could be len(a)).
 // The slice must be sorted in ascending order.
 //
diff --git a/libgo/go/sort/search_test.go b/libgo/go/sort/search_test.go
index 4265b9520a6..e75508dbda1 100644
--- a/libgo/go/sort/search_test.go
+++ b/libgo/go/sort/search_test.go
@@ -148,7 +148,7 @@ func BenchmarkSearchWrappers(b *testing.B) {
 }
 
 // Abstract exhaustive test: all sizes up to 100,
-// all possible return values.  If there are any small
+// all possible return values. If there are any small
 // corner cases, this test exercises them.
 func TestSearchExhaustive(t *testing.T) {
 	for size := 0; size <= 100; size++ {
diff --git a/libgo/go/sort/sort.go b/libgo/go/sort/sort.go
index ac8f4a661fc..d07a0c27b84 100644
--- a/libgo/go/sort/sort.go
+++ b/libgo/go/sort/sort.go
@@ -7,7 +7,7 @@
 package sort
 
 // A type, typically a collection, that satisfies sort.Interface can be
-// sorted by the routines in this package.  The methods require that the
+// sorted by the routines in this package. The methods require that the
 // elements of the collection be enumerated by an integer index.
 type Interface interface {
 	// Len is the number of elements in the collection.
@@ -19,13 +19,6 @@ type Interface interface {
 	Swap(i, j int)
 }
 
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
 // Insertion sort
 func insertionSort(data Interface, a, b int) {
 	for i := a + 1; i < b; i++ {
@@ -119,15 +112,15 @@ func doPivot(data Interface, lo, hi int) (midlo, midhi int) {
 	pivot := lo
 	a, c := lo+1, hi-1
 
-	for ; a != c && data.Less(a, pivot); a++ {
+	for ; a < c && data.Less(a, pivot); a++ {
 	}
 	b := a
 	for {
-		for ; b != c && !data.Less(pivot, b); b++ { // data[b] <= pivot
+		for ; b < c && !data.Less(pivot, b); b++ { // data[b] <= pivot
 		}
-		for ; b != c && data.Less(pivot, c-1); c-- { // data[c-1] > pivot
+		for ; b < c && data.Less(pivot, c-1); c-- { // data[c-1] > pivot
 		}
-		if b == c {
+		if b >= c {
 			break
 		}
 		// data[b] > pivot; data[c-1] <= pivot
@@ -167,11 +160,11 @@ func doPivot(data Interface, lo, hi int) (midlo, midhi int) {
 		//	data[a <= i < b] unexamined
 		//	data[b <= i < c] = pivot
 		for {
-			for ; a != b && !data.Less(b-1, pivot); b-- { // data[b] == pivot
+			for ; a < b && !data.Less(b-1, pivot); b-- { // data[b] == pivot
 			}
-			for ; a != b && data.Less(a, pivot); a++ { // data[a] < pivot
+			for ; a < b && data.Less(a, pivot); a++ { // data[a] < pivot
 			}
-			if a == b {
+			if a >= b {
 				break
 			}
 			// data[a] == pivot; data[b-1] < pivot
@@ -315,7 +308,7 @@ func StringsAreSorted(a []string) bool { return IsSorted(StringSlice(a)) }
 
 // Notes on stable sorting:
 // The used algorithms are simple and provable correct on all input and use
-// only logarithmic additional stack space.  They perform well if compared
+// only logarithmic additional stack space. They perform well if compared
 // experimentally to other stable in-place sorting algorithms.
 //
 // Remarks on other algorithms evaluated:
@@ -335,7 +328,7 @@ func StringsAreSorted(a []string) bool { return IsSorted(StringSlice(a)) }
 //    unstable or rely on enough different elements in each step to encode the
 //    performed block rearrangements. See also "In-Place Merging Algorithms",
 //    Denham Coates-Evely, Department of Computer Science, Kings College,
-//    January 2004 and the reverences in there.
+//    January 2004 and the references in there.
 //  - Often "optimal" algorithms are optimal in the number of assignments
 //    but Interface has only Swap as operation.
 
diff --git a/libgo/go/sort/sort_test.go b/libgo/go/sort/sort_test.go
index 6c36f30e0ee..60fac2d6951 100644
--- a/libgo/go/sort/sort_test.go
+++ b/libgo/go/sort/sort_test.go
@@ -109,6 +109,43 @@ func TestReverseSortIntSlice(t *testing.T) {
 	}
 }
 
+type nonDeterministicTestingData struct {
+	r *rand.Rand
+}
+
+func (t *nonDeterministicTestingData) Len() int {
+	return 500
+}
+func (t *nonDeterministicTestingData) Less(i, j int) bool {
+	if i < 0 || j < 0 || i >= t.Len() || j >= t.Len() {
+		panic("nondeterministic comparison out of bounds")
+	}
+	return t.r.Float32() < 0.5
+}
+func (t *nonDeterministicTestingData) Swap(i, j int) {
+	if i < 0 || j < 0 || i >= t.Len() || j >= t.Len() {
+		panic("nondeterministic comparison out of bounds")
+	}
+}
+
+func TestNonDeterministicComparison(t *testing.T) {
+	// Ensure that sort.Sort does not panic when Less returns inconsistent results.
+	// See https://golang.org/issue/14377.
+	defer func() {
+		if r := recover(); r != nil {
+			t.Error(r)
+		}
+	}()
+
+	td := &nonDeterministicTestingData{
+		r: rand.New(rand.NewSource(0)),
+	}
+
+	for i := 0; i < 10; i++ {
+		Sort(td)
+	}
+}
+
 func BenchmarkSortString1K(b *testing.B) {
 	b.StopTimer()
 	for i := 0; i < b.N; i++ {
@@ -469,10 +506,10 @@ func TestStability(t *testing.T) {
 	data.initB()
 	Stable(data)
 	if !IsSorted(data) {
-		t.Errorf("Stable shuffeled sorted %d ints (order)", n)
+		t.Errorf("Stable shuffled sorted %d ints (order)", n)
 	}
 	if !data.inOrder() {
-		t.Errorf("Stable shuffeled sorted %d ints (stability)", n)
+		t.Errorf("Stable shuffled sorted %d ints (stability)", n)
 	}
 
 	// sorted reversed
diff --git a/libgo/go/strconv/atob.go b/libgo/go/strconv/atob.go
index d0cb097213f..879ceb385ed 100644
--- a/libgo/go/strconv/atob.go
+++ b/libgo/go/strconv/atob.go
@@ -7,7 +7,7 @@ package strconv
 // ParseBool returns the boolean value represented by the string.
 // It accepts 1, t, T, TRUE, true, True, 0, f, F, FALSE, false, False.
 // Any other value returns an error.
-func ParseBool(str string) (value bool, err error) {
+func ParseBool(str string) (bool, error) {
 	switch str {
 	case "1", "t", "T", "true", "TRUE", "True":
 		return true, nil
diff --git a/libgo/go/strconv/atof.go b/libgo/go/strconv/atof.go
index a4f4862dba9..fdcb8b3d7a5 100644
--- a/libgo/go/strconv/atof.go
+++ b/libgo/go/strconv/atof.go
@@ -245,7 +245,9 @@ func readFloat(s string) (mantissa uint64, exp int, neg, trunc, ok bool) {
 		return
 	}
 
-	exp = dp - ndMant
+	if mantissa != 0 {
+		exp = dp - ndMant
+	}
 	ok = true
 	return
 
@@ -534,11 +536,10 @@ func atof64(s string) (f float64, err error) {
 // If s is syntactically well-formed but is more than 1/2 ULP
 // away from the largest floating point number of the given size,
 // ParseFloat returns f = ±Inf, err.Err = ErrRange.
-func ParseFloat(s string, bitSize int) (f float64, err error) {
+func ParseFloat(s string, bitSize int) (float64, error) {
 	if bitSize == 32 {
-		f1, err1 := atof32(s)
-		return float64(f1), err1
+		f, err := atof32(s)
+		return float64(f), err
 	}
-	f1, err1 := atof64(s)
-	return f1, err1
+	return atof64(s)
 }
diff --git a/libgo/go/strconv/atof_test.go b/libgo/go/strconv/atof_test.go
index ba4933218b0..0a89c3e0bfa 100644
--- a/libgo/go/strconv/atof_test.go
+++ b/libgo/go/strconv/atof_test.go
@@ -42,6 +42,30 @@ var atoftests = []atofTest{
 	{"1e-20", "1e-20", nil},
 	{"625e-3", "0.625", nil},
 
+	// zeros
+	{"0", "0", nil},
+	{"0e0", "0", nil},
+	{"-0e0", "-0", nil},
+	{"+0e0", "0", nil},
+	{"0e-0", "0", nil},
+	{"-0e-0", "-0", nil},
+	{"+0e-0", "0", nil},
+	{"0e+0", "0", nil},
+	{"-0e+0", "-0", nil},
+	{"+0e+0", "0", nil},
+	{"0e+01234567890123456789", "0", nil},
+	{"0.00e-01234567890123456789", "0", nil},
+	{"-0e+01234567890123456789", "-0", nil},
+	{"-0.00e-01234567890123456789", "-0", nil},
+	{"0e291", "0", nil}, // issue 15364
+	{"0e292", "0", nil}, // issue 15364
+	{"0e347", "0", nil}, // issue 15364
+	{"0e348", "0", nil}, // issue 15364
+	{"-0e291", "-0", nil},
+	{"-0e292", "-0", nil},
+	{"-0e347", "-0", nil},
+	{"-0e348", "-0", nil},
+
 	// NaNs
 	{"nan", "NaN", nil},
 	{"NaN", "NaN", nil},
@@ -196,7 +220,7 @@ var (
 
 func init() {
 	// The atof routines return NumErrors wrapping
-	// the error and the string.  Convert the table above.
+	// the error and the string. Convert the table above.
 	for i := range atoftests {
 		test := &atoftests[i]
 		if test.err != nil {
diff --git a/libgo/go/strconv/atoi.go b/libgo/go/strconv/atoi.go
index 965e3a218fd..a236de421c6 100644
--- a/libgo/go/strconv/atoi.go
+++ b/libgo/go/strconv/atoi.go
@@ -39,7 +39,9 @@ const IntSize = intSize
 const maxUint64 = (1<<64 - 1)
 
 // ParseUint is like ParseInt but for unsigned numbers.
-func ParseUint(s string, base int, bitSize int) (n uint64, err error) {
+func ParseUint(s string, base int, bitSize int) (uint64, error) {
+	var n uint64
+	var err error
 	var cutoff, maxVal uint64
 
 	if bitSize == 0 {
@@ -136,16 +138,16 @@ Error:
 }
 
 // ParseInt interprets a string s in the given base (2 to 36) and
-// returns the corresponding value i.  If base == 0, the base is
+// returns the corresponding value i. If base == 0, the base is
 // implied by the string's prefix: base 16 for "0x", base 8 for
 // "0", and base 10 otherwise.
 //
 // The bitSize argument specifies the integer type
-// that the result must fit into.  Bit sizes 0, 8, 16, 32, and 64
+// that the result must fit into. Bit sizes 0, 8, 16, 32, and 64
 // correspond to int, int8, int16, int32, and int64.
 //
 // The errors that ParseInt returns have concrete type *NumError
-// and include err.Num = s.  If s is empty or contains invalid
+// and include err.Num = s. If s is empty or contains invalid
 // digits, err.Err = ErrSyntax and the returned value is 0;
 // if the value corresponding to s cannot be represented by a
 // signed integer of the given size, err.Err = ErrRange and the
@@ -195,8 +197,8 @@ func ParseInt(s string, base int, bitSize int) (i int64, err error) {
 	return n, nil
 }
 
-// Atoi is shorthand for ParseInt(s, 10, 0).
-func Atoi(s string) (i int, err error) {
+// Atoi returns the result of ParseInt(s, 10, 0) converted to type int.
+func Atoi(s string) (int, error) {
 	i64, err := ParseInt(s, 10, 0)
 	return int(i64), err
 }
diff --git a/libgo/go/strconv/atoi_test.go b/libgo/go/strconv/atoi_test.go
index bd6a6a01fa1..d608505da21 100644
--- a/libgo/go/strconv/atoi_test.go
+++ b/libgo/go/strconv/atoi_test.go
@@ -196,7 +196,7 @@ var numErrorTests = []numErrorTest{
 
 func init() {
 	// The atoi routines return NumErrors wrapping
-	// the error and the string.  Convert the tables above.
+	// the error and the string. Convert the tables above.
 	for i := range atoui64tests {
 		test := &atoui64tests[i]
 		if test.err != nil {
diff --git a/libgo/go/strconv/extfloat.go b/libgo/go/strconv/extfloat.go
index 019b4eebdc9..7033e96c39e 100644
--- a/libgo/go/strconv/extfloat.go
+++ b/libgo/go/strconv/extfloat.go
@@ -311,9 +311,9 @@ func (f *extFloat) AssignDecimal(mantissa uint64, exp10 int, neg bool, trunc boo
 	var extrabits uint
 	if f.exp <= denormalExp {
 		// f.mant * 2^f.exp is smaller than 2^(flt.bias+1).
-		extrabits = uint(63 - flt.mantbits + 1 + uint(denormalExp-f.exp))
+		extrabits = 63 - flt.mantbits + 1 + uint(denormalExp-f.exp)
 	} else {
-		extrabits = uint(63 - flt.mantbits)
+		extrabits = 63 - flt.mantbits
 	}
 
 	halfway := uint64(1) << (extrabits - 1)
diff --git a/libgo/go/strconv/fp_test.go b/libgo/go/strconv/fp_test.go
index 6de2f8bc6f2..39dd9c4a581 100644
--- a/libgo/go/strconv/fp_test.go
+++ b/libgo/go/strconv/fp_test.go
@@ -41,7 +41,7 @@ func myatof64(s string) (f float64, ok bool) {
 		}
 		v := float64(n)
 		// We expect that v*pow2(e) fits in a float64,
-		// but pow2(e) by itself may not.  Be careful.
+		// but pow2(e) by itself may not. Be careful.
 		if e <= -1000 {
 			v *= pow2(-1000)
 			e += 1000
diff --git a/libgo/go/strconv/ftoa.go b/libgo/go/strconv/ftoa.go
index 9ff5d1056aa..8b3d33e4e77 100644
--- a/libgo/go/strconv/ftoa.go
+++ b/libgo/go/strconv/ftoa.go
@@ -23,7 +23,7 @@ var float32info = floatInfo{23, 8, -127}
 var float64info = floatInfo{52, 11, -1023}
 
 // FormatFloat converts the floating-point number f to a string,
-// according to the format fmt and precision prec.  It rounds the
+// according to the format fmt and precision prec. It rounds the
 // result assuming that the original was obtained from a floating-point
 // value of bitSize bits (32 for float32, 64 for float64).
 //
diff --git a/libgo/go/strconv/ftoa_test.go b/libgo/go/strconv/ftoa_test.go
index 0b9f0feafa6..1d25242ff3f 100644
--- a/libgo/go/strconv/ftoa_test.go
+++ b/libgo/go/strconv/ftoa_test.go
@@ -183,59 +183,50 @@ func TestFtoaRandom(t *testing.T) {
 	}
 }
 
-func BenchmarkFormatFloatDecimal(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		FormatFloat(33909, 'g', -1, 64)
-	}
+var ftoaBenches = []struct {
+	name    string
+	float   float64
+	fmt     byte
+	prec    int
+	bitSize int
+}{
+	{"Decimal", 33909, 'g', -1, 64},
+	{"Float", 339.7784, 'g', -1, 64},
+	{"Exp", -5.09e75, 'g', -1, 64},
+	{"NegExp", -5.11e-95, 'g', -1, 64},
+
+	{"Big", 123456789123456789123456789, 'g', -1, 64},
+	{"BinaryExp", -1, 'b', -1, 64},
+
+	{"32Integer", 33909, 'g', -1, 32},
+	{"32ExactFraction", 3.375, 'g', -1, 32},
+	{"32Point", 339.7784, 'g', -1, 32},
+	{"32Exp", -5.09e25, 'g', -1, 32},
+	{"32NegExp", -5.11e-25, 'g', -1, 32},
+
+	{"64Fixed1", 123456, 'e', 3, 64},
+	{"64Fixed2", 123.456, 'e', 3, 64},
+	{"64Fixed3", 1.23456e+78, 'e', 3, 64},
+	{"64Fixed4", 1.23456e-78, 'e', 3, 64},
 }
 
 func BenchmarkFormatFloat(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		FormatFloat(339.7784, 'g', -1, 64)
-	}
-}
-
-func BenchmarkFormatFloatExp(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		FormatFloat(-5.09e75, 'g', -1, 64)
-	}
-}
-
-func BenchmarkFormatFloatNegExp(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		FormatFloat(-5.11e-95, 'g', -1, 64)
-	}
-}
-
-func BenchmarkFormatFloatBig(b *testing.B) {
-	for i := 0; i < b.N; i++ {
-		FormatFloat(123456789123456789123456789, 'g', -1, 64)
+	for _, c := range ftoaBenches {
+		b.Run(c.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				FormatFloat(c.float, c.fmt, c.prec, c.bitSize)
+			}
+		})
 	}
 }
 
-func benchmarkAppendFloat(b *testing.B, f float64, fmt byte, prec, bitSize int) {
+func BenchmarkAppendFloat(b *testing.B) {
 	dst := make([]byte, 30)
-	for i := 0; i < b.N; i++ {
-		AppendFloat(dst[:0], f, fmt, prec, bitSize)
+	for _, c := range ftoaBenches {
+		b.Run(c.name, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				AppendFloat(dst[:0], c.float, c.fmt, c.prec, c.bitSize)
+			}
+		})
 	}
 }
-
-func BenchmarkAppendFloatDecimal(b *testing.B) { benchmarkAppendFloat(b, 33909, 'g', -1, 64) }
-func BenchmarkAppendFloat(b *testing.B)        { benchmarkAppendFloat(b, 339.7784, 'g', -1, 64) }
-func BenchmarkAppendFloatExp(b *testing.B)     { benchmarkAppendFloat(b, -5.09e75, 'g', -1, 64) }
-func BenchmarkAppendFloatNegExp(b *testing.B)  { benchmarkAppendFloat(b, -5.11e-95, 'g', -1, 64) }
-func BenchmarkAppendFloatBig(b *testing.B) {
-	benchmarkAppendFloat(b, 123456789123456789123456789, 'g', -1, 64)
-}
-func BenchmarkAppendFloatBinaryExp(b *testing.B) { benchmarkAppendFloat(b, -1, 'b', -1, 64) }
-
-func BenchmarkAppendFloat32Integer(b *testing.B)       { benchmarkAppendFloat(b, 33909, 'g', -1, 32) }
-func BenchmarkAppendFloat32ExactFraction(b *testing.B) { benchmarkAppendFloat(b, 3.375, 'g', -1, 32) }
-func BenchmarkAppendFloat32Point(b *testing.B)         { benchmarkAppendFloat(b, 339.7784, 'g', -1, 32) }
-func BenchmarkAppendFloat32Exp(b *testing.B)           { benchmarkAppendFloat(b, -5.09e25, 'g', -1, 32) }
-func BenchmarkAppendFloat32NegExp(b *testing.B)        { benchmarkAppendFloat(b, -5.11e-25, 'g', -1, 32) }
-
-func BenchmarkAppendFloat64Fixed1(b *testing.B) { benchmarkAppendFloat(b, 123456, 'e', 3, 64) }
-func BenchmarkAppendFloat64Fixed2(b *testing.B) { benchmarkAppendFloat(b, 123.456, 'e', 3, 64) }
-func BenchmarkAppendFloat64Fixed3(b *testing.B) { benchmarkAppendFloat(b, 1.23456e+78, 'e', 3, 64) }
-func BenchmarkAppendFloat64Fixed4(b *testing.B) { benchmarkAppendFloat(b, 1.23456e-78, 'e', 3, 64) }
diff --git a/libgo/go/strconv/isprint.go b/libgo/go/strconv/isprint.go
index 20a02dec33f..a30d8d8b59c 100644
--- a/libgo/go/strconv/isprint.go
+++ b/libgo/go/strconv/isprint.go
@@ -7,7 +7,7 @@
 
 package strconv
 
-// (470+136+73)*2 + (342)*4 = 2726 bytes
+// (462+139+82)*2 + (378)*4 = 2878 bytes
 
 var isPrint16 = []uint16{
 	0x0020, 0x007e,
@@ -26,8 +26,8 @@ var isPrint16 = []uint16{
 	0x0800, 0x082d,
 	0x0830, 0x085b,
 	0x085e, 0x085e,
-	0x08a0, 0x08b4,
-	0x08e3, 0x098c,
+	0x08a0, 0x08bd,
+	0x08d4, 0x098c,
 	0x098f, 0x0990,
 	0x0993, 0x09b2,
 	0x09b6, 0x09b9,
@@ -83,11 +83,9 @@ var isPrint16 = []uint16{
 	0x0cde, 0x0ce3,
 	0x0ce6, 0x0cf2,
 	0x0d01, 0x0d3a,
-	0x0d3d, 0x0d4e,
-	0x0d57, 0x0d57,
-	0x0d5f, 0x0d63,
-	0x0d66, 0x0d75,
-	0x0d79, 0x0d7f,
+	0x0d3d, 0x0d4f,
+	0x0d54, 0x0d63,
+	0x0d66, 0x0d7f,
 	0x0d82, 0x0d96,
 	0x0d9a, 0x0dbd,
 	0x0dc0, 0x0dc6,
@@ -153,11 +151,11 @@ var isPrint16 = []uint16{
 	0x1b80, 0x1bf3,
 	0x1bfc, 0x1c37,
 	0x1c3b, 0x1c49,
-	0x1c4d, 0x1c7f,
+	0x1c4d, 0x1c88,
 	0x1cc0, 0x1cc7,
 	0x1cd0, 0x1cf9,
 	0x1d00, 0x1df5,
-	0x1dfc, 0x1f15,
+	0x1dfb, 0x1f15,
 	0x1f18, 0x1f1d,
 	0x1f20, 0x1f45,
 	0x1f48, 0x1f4d,
@@ -172,8 +170,7 @@ var isPrint16 = []uint16{
 	0x20a0, 0x20be,
 	0x20d0, 0x20f0,
 	0x2100, 0x218b,
-	0x2190, 0x23fa,
-	0x2400, 0x2426,
+	0x2190, 0x2426,
 	0x2440, 0x244a,
 	0x2460, 0x2b73,
 	0x2b76, 0x2b95,
@@ -186,7 +183,7 @@ var isPrint16 = []uint16{
 	0x2d30, 0x2d67,
 	0x2d6f, 0x2d70,
 	0x2d7f, 0x2d96,
-	0x2da0, 0x2e42,
+	0x2da0, 0x2e44,
 	0x2e80, 0x2ef3,
 	0x2f00, 0x2fd5,
 	0x2ff0, 0x2ffb,
@@ -201,12 +198,11 @@ var isPrint16 = []uint16{
 	0xa490, 0xa4c6,
 	0xa4d0, 0xa62b,
 	0xa640, 0xa6f7,
-	0xa700, 0xa7ad,
-	0xa7b0, 0xa7b7,
+	0xa700, 0xa7b7,
 	0xa7f7, 0xa82b,
 	0xa830, 0xa839,
 	0xa840, 0xa877,
-	0xa880, 0xa8c4,
+	0xa880, 0xa8c5,
 	0xa8ce, 0xa8d9,
 	0xa8e0, 0xa8fd,
 	0xa900, 0xa953,
@@ -258,6 +254,8 @@ var isNotPrint16 = []uint16{
 	0x0590,
 	0x06dd,
 	0x083f,
+	0x08b5,
+	0x08e2,
 	0x0984,
 	0x09a9,
 	0x09b1,
@@ -294,7 +292,6 @@ var isNotPrint16 = []uint16{
 	0x0c45,
 	0x0c49,
 	0x0c57,
-	0x0c80,
 	0x0c84,
 	0x0c8d,
 	0x0c91,
@@ -354,6 +351,7 @@ var isNotPrint16 = []uint16{
 	0x1fdc,
 	0x1ff5,
 	0x208f,
+	0x23ff,
 	0x2bc9,
 	0x2c2f,
 	0x2c5f,
@@ -371,6 +369,7 @@ var isNotPrint16 = []uint16{
 	0x318f,
 	0x321f,
 	0x32ff,
+	0xa7af,
 	0xa9ce,
 	0xa9ff,
 	0xab27,
@@ -392,8 +391,7 @@ var isPrint32 = []uint32{
 	0x010080, 0x0100fa,
 	0x010100, 0x010102,
 	0x010107, 0x010133,
-	0x010137, 0x01018c,
-	0x010190, 0x01019b,
+	0x010137, 0x01019b,
 	0x0101a0, 0x0101a0,
 	0x0101d0, 0x0101fd,
 	0x010280, 0x01029c,
@@ -406,6 +404,8 @@ var isPrint32 = []uint32{
 	0x0103c8, 0x0103d5,
 	0x010400, 0x01049d,
 	0x0104a0, 0x0104a9,
+	0x0104b0, 0x0104d3,
+	0x0104d8, 0x0104fb,
 	0x010500, 0x010527,
 	0x010530, 0x010563,
 	0x01056f, 0x01056f,
@@ -451,7 +451,7 @@ var isPrint32 = []uint32{
 	0x011150, 0x011176,
 	0x011180, 0x0111cd,
 	0x0111d0, 0x0111f4,
-	0x011200, 0x01123d,
+	0x011200, 0x01123e,
 	0x011280, 0x0112a9,
 	0x0112b0, 0x0112ea,
 	0x0112f0, 0x0112f9,
@@ -466,12 +466,14 @@ var isPrint32 = []uint32{
 	0x01135d, 0x011363,
 	0x011366, 0x01136c,
 	0x011370, 0x011374,
+	0x011400, 0x01145d,
 	0x011480, 0x0114c7,
 	0x0114d0, 0x0114d9,
 	0x011580, 0x0115b5,
 	0x0115b8, 0x0115dd,
 	0x011600, 0x011644,
 	0x011650, 0x011659,
+	0x011660, 0x01166c,
 	0x011680, 0x0116b7,
 	0x0116c0, 0x0116c9,
 	0x011700, 0x011719,
@@ -480,6 +482,10 @@ var isPrint32 = []uint32{
 	0x0118a0, 0x0118f2,
 	0x0118ff, 0x0118ff,
 	0x011ac0, 0x011af8,
+	0x011c00, 0x011c45,
+	0x011c50, 0x011c6c,
+	0x011c70, 0x011c8f,
+	0x011c92, 0x011cb6,
 	0x012000, 0x012399,
 	0x012400, 0x012474,
 	0x012480, 0x012543,
@@ -496,6 +502,9 @@ var isPrint32 = []uint32{
 	0x016f00, 0x016f44,
 	0x016f50, 0x016f7e,
 	0x016f8f, 0x016f9f,
+	0x016fe0, 0x016fe0,
+	0x017000, 0x0187ec,
+	0x018800, 0x018af2,
 	0x01b000, 0x01b001,
 	0x01bc00, 0x01bc6a,
 	0x01bc70, 0x01bc7c,
@@ -518,8 +527,13 @@ var isPrint32 = []uint32{
 	0x01d6a8, 0x01d7cb,
 	0x01d7ce, 0x01da8b,
 	0x01da9b, 0x01daaf,
+	0x01e000, 0x01e018,
+	0x01e01b, 0x01e02a,
 	0x01e800, 0x01e8c4,
 	0x01e8c7, 0x01e8d6,
+	0x01e900, 0x01e94a,
+	0x01e950, 0x01e959,
+	0x01e95e, 0x01e95f,
 	0x01ee00, 0x01ee24,
 	0x01ee27, 0x01ee3b,
 	0x01ee42, 0x01ee42,
@@ -534,14 +548,14 @@ var isPrint32 = []uint32{
 	0x01f0b1, 0x01f0f5,
 	0x01f100, 0x01f10c,
 	0x01f110, 0x01f16b,
-	0x01f170, 0x01f19a,
+	0x01f170, 0x01f1ac,
 	0x01f1e6, 0x01f202,
-	0x01f210, 0x01f23a,
+	0x01f210, 0x01f23b,
 	0x01f240, 0x01f248,
 	0x01f250, 0x01f251,
-	0x01f300, 0x01f6d0,
+	0x01f300, 0x01f6d2,
 	0x01f6e0, 0x01f6ec,
-	0x01f6f0, 0x01f6f3,
+	0x01f6f0, 0x01f6f6,
 	0x01f700, 0x01f773,
 	0x01f780, 0x01f7d4,
 	0x01f800, 0x01f80b,
@@ -549,8 +563,11 @@ var isPrint32 = []uint32{
 	0x01f850, 0x01f859,
 	0x01f860, 0x01f887,
 	0x01f890, 0x01f8ad,
-	0x01f910, 0x01f918,
-	0x01f980, 0x01f984,
+	0x01f910, 0x01f927,
+	0x01f930, 0x01f930,
+	0x01f933, 0x01f94b,
+	0x01f950, 0x01f95e,
+	0x01f980, 0x01f991,
 	0x01f9c0, 0x01f9c0,
 	0x020000, 0x02a6d6,
 	0x02a700, 0x02b734,
@@ -565,6 +582,7 @@ var isNotPrint32 = []uint16{ // add 0x10000 to each entry
 	0x0027,
 	0x003b,
 	0x003e,
+	0x018f,
 	0x039e,
 	0x0809,
 	0x0836,
@@ -585,6 +603,11 @@ var isNotPrint32 = []uint16{ // add 0x10000 to each entry
 	0x1329,
 	0x1331,
 	0x1334,
+	0x145a,
+	0x145c,
+	0x1c09,
+	0x1c37,
+	0x1ca8,
 	0x246f,
 	0x6a5f,
 	0x6b5a,
@@ -603,6 +626,9 @@ var isNotPrint32 = []uint16{ // add 0x10000 to each entry
 	0xd545,
 	0xd551,
 	0xdaa0,
+	0xe007,
+	0xe022,
+	0xe025,
 	0xee04,
 	0xee20,
 	0xee23,
@@ -632,8 +658,8 @@ var isNotPrint32 = []uint16{ // add 0x10000 to each entry
 	0xf0c0,
 	0xf0d0,
 	0xf12f,
-	0xf57a,
-	0xf5a4,
+	0xf91f,
+	0xf93f,
 }
 
 // isGraphic lists the graphic runes not matched by IsPrint.
diff --git a/libgo/go/strconv/makeisprint.go b/libgo/go/strconv/makeisprint.go
index 514258060e5..0a3e5b20cce 100644
--- a/libgo/go/strconv/makeisprint.go
+++ b/libgo/go/strconv/makeisprint.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/strconv/quote.go b/libgo/go/strconv/quote.go
index 40d0667551a..becfe1df075 100644
--- a/libgo/go/strconv/quote.go
+++ b/libgo/go/strconv/quote.go
@@ -6,15 +6,19 @@
 
 package strconv
 
-import (
-	"unicode/utf8"
-)
+import "unicode/utf8"
 
 const lowerhex = "0123456789abcdef"
 
 func quoteWith(s string, quote byte, ASCIIonly, graphicOnly bool) string {
-	var runeTmp [utf8.UTFMax]byte
-	buf := make([]byte, 0, 3*len(s)/2) // Try to avoid more allocations.
+	return string(appendQuotedWith(make([]byte, 0, 3*len(s)/2), s, quote, ASCIIonly, graphicOnly))
+}
+
+func quoteRuneWith(r rune, quote byte, ASCIIonly, graphicOnly bool) string {
+	return string(appendQuotedRuneWith(nil, r, quote, ASCIIonly, graphicOnly))
+}
+
+func appendQuotedWith(buf []byte, s string, quote byte, ASCIIonly, graphicOnly bool) []byte {
 	buf = append(buf, quote)
 	for width := 0; len(s) > 0; s = s[width:] {
 		r := rune(s[0])
@@ -28,64 +32,79 @@ func quoteWith(s string, quote byte, ASCIIonly, graphicOnly bool) string {
 			buf = append(buf, lowerhex[s[0]&0xF])
 			continue
 		}
-		if r == rune(quote) || r == '\\' { // always backslashed
-			buf = append(buf, '\\')
+		buf = appendEscapedRune(buf, r, width, quote, ASCIIonly, graphicOnly)
+	}
+	buf = append(buf, quote)
+	return buf
+}
+
+func appendQuotedRuneWith(buf []byte, r rune, quote byte, ASCIIonly, graphicOnly bool) []byte {
+	buf = append(buf, quote)
+	if !utf8.ValidRune(r) {
+		r = utf8.RuneError
+	}
+	buf = appendEscapedRune(buf, r, utf8.RuneLen(r), quote, ASCIIonly, graphicOnly)
+	buf = append(buf, quote)
+	return buf
+}
+
+func appendEscapedRune(buf []byte, r rune, width int, quote byte, ASCIIonly, graphicOnly bool) []byte {
+	var runeTmp [utf8.UTFMax]byte
+	if r == rune(quote) || r == '\\' { // always backslashed
+		buf = append(buf, '\\')
+		buf = append(buf, byte(r))
+		return buf
+	}
+	if ASCIIonly {
+		if r < utf8.RuneSelf && IsPrint(r) {
 			buf = append(buf, byte(r))
-			continue
+			return buf
 		}
-		if ASCIIonly {
-			if r < utf8.RuneSelf && IsPrint(r) {
-				buf = append(buf, byte(r))
-				continue
+	} else if IsPrint(r) || graphicOnly && isInGraphicList(r) {
+		n := utf8.EncodeRune(runeTmp[:], r)
+		buf = append(buf, runeTmp[:n]...)
+		return buf
+	}
+	switch r {
+	case '\a':
+		buf = append(buf, `\a`...)
+	case '\b':
+		buf = append(buf, `\b`...)
+	case '\f':
+		buf = append(buf, `\f`...)
+	case '\n':
+		buf = append(buf, `\n`...)
+	case '\r':
+		buf = append(buf, `\r`...)
+	case '\t':
+		buf = append(buf, `\t`...)
+	case '\v':
+		buf = append(buf, `\v`...)
+	default:
+		switch {
+		case r < ' ':
+			buf = append(buf, `\x`...)
+			buf = append(buf, lowerhex[byte(r)>>4])
+			buf = append(buf, lowerhex[byte(r)&0xF])
+		case r > utf8.MaxRune:
+			r = 0xFFFD
+			fallthrough
+		case r < 0x10000:
+			buf = append(buf, `\u`...)
+			for s := 12; s >= 0; s -= 4 {
+				buf = append(buf, lowerhex[r>>uint(s)&0xF])
 			}
-		} else if IsPrint(r) || graphicOnly && isInGraphicList(r) {
-			n := utf8.EncodeRune(runeTmp[:], r)
-			buf = append(buf, runeTmp[:n]...)
-			continue
-		}
-		switch r {
-		case '\a':
-			buf = append(buf, `\a`...)
-		case '\b':
-			buf = append(buf, `\b`...)
-		case '\f':
-			buf = append(buf, `\f`...)
-		case '\n':
-			buf = append(buf, `\n`...)
-		case '\r':
-			buf = append(buf, `\r`...)
-		case '\t':
-			buf = append(buf, `\t`...)
-		case '\v':
-			buf = append(buf, `\v`...)
 		default:
-			switch {
-			case r < ' ':
-				buf = append(buf, `\x`...)
-				buf = append(buf, lowerhex[s[0]>>4])
-				buf = append(buf, lowerhex[s[0]&0xF])
-			case r > utf8.MaxRune:
-				r = 0xFFFD
-				fallthrough
-			case r < 0x10000:
-				buf = append(buf, `\u`...)
-				for s := 12; s >= 0; s -= 4 {
-					buf = append(buf, lowerhex[r>>uint(s)&0xF])
-				}
-			default:
-				buf = append(buf, `\U`...)
-				for s := 28; s >= 0; s -= 4 {
-					buf = append(buf, lowerhex[r>>uint(s)&0xF])
-				}
+			buf = append(buf, `\U`...)
+			for s := 28; s >= 0; s -= 4 {
+				buf = append(buf, lowerhex[r>>uint(s)&0xF])
 			}
 		}
 	}
-	buf = append(buf, quote)
-	return string(buf)
-
+	return buf
 }
 
-// Quote returns a double-quoted Go string literal representing s.  The
+// Quote returns a double-quoted Go string literal representing s. The
 // returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
 // control characters and non-printable characters as defined by
 // IsPrint.
@@ -96,7 +115,7 @@ func Quote(s string) string {
 // AppendQuote appends a double-quoted Go string literal representing s,
 // as generated by Quote, to dst and returns the extended buffer.
 func AppendQuote(dst []byte, s string) []byte {
-	return append(dst, Quote(s)...)
+	return appendQuotedWith(dst, s, '"', false, false)
 }
 
 // QuoteToASCII returns a double-quoted Go string literal representing s.
@@ -109,7 +128,7 @@ func QuoteToASCII(s string) string {
 // AppendQuoteToASCII appends a double-quoted Go string literal representing s,
 // as generated by QuoteToASCII, to dst and returns the extended buffer.
 func AppendQuoteToASCII(dst []byte, s string) []byte {
-	return append(dst, QuoteToASCII(s)...)
+	return appendQuotedWith(dst, s, '"', true, false)
 }
 
 // QuoteToGraphic returns a double-quoted Go string literal representing s.
@@ -122,21 +141,20 @@ func QuoteToGraphic(s string) string {
 // AppendQuoteToGraphic appends a double-quoted Go string literal representing s,
 // as generated by QuoteToGraphic, to dst and returns the extended buffer.
 func AppendQuoteToGraphic(dst []byte, s string) []byte {
-	return append(dst, QuoteToGraphic(s)...)
+	return appendQuotedWith(dst, s, '"', false, true)
 }
 
 // QuoteRune returns a single-quoted Go character literal representing the
 // rune. The returned string uses Go escape sequences (\t, \n, \xFF, \u0100)
 // for control characters and non-printable characters as defined by IsPrint.
 func QuoteRune(r rune) string {
-	// TODO: avoid the allocation here.
-	return quoteWith(string(r), '\'', false, false)
+	return quoteRuneWith(r, '\'', false, false)
 }
 
 // AppendQuoteRune appends a single-quoted Go character literal representing the rune,
 // as generated by QuoteRune, to dst and returns the extended buffer.
 func AppendQuoteRune(dst []byte, r rune) []byte {
-	return append(dst, QuoteRune(r)...)
+	return appendQuotedRuneWith(dst, r, '\'', false, false)
 }
 
 // QuoteRuneToASCII returns a single-quoted Go character literal representing
@@ -144,14 +162,13 @@ func AppendQuoteRune(dst []byte, r rune) []byte {
 // \u0100) for non-ASCII characters and non-printable characters as defined
 // by IsPrint.
 func QuoteRuneToASCII(r rune) string {
-	// TODO: avoid the allocation here.
-	return quoteWith(string(r), '\'', true, false)
+	return quoteRuneWith(r, '\'', true, false)
 }
 
 // AppendQuoteRuneToASCII appends a single-quoted Go character literal representing the rune,
 // as generated by QuoteRuneToASCII, to dst and returns the extended buffer.
 func AppendQuoteRuneToASCII(dst []byte, r rune) []byte {
-	return append(dst, QuoteRuneToASCII(r)...)
+	return appendQuotedRuneWith(dst, r, '\'', true, false)
 }
 
 // QuoteRuneToGraphic returns a single-quoted Go character literal representing
@@ -159,14 +176,13 @@ func AppendQuoteRuneToASCII(dst []byte, r rune) []byte {
 // \u0100) for non-ASCII characters and non-printable characters as defined
 // by IsGraphic.
 func QuoteRuneToGraphic(r rune) string {
-	// TODO: avoid the allocation here.
-	return quoteWith(string(r), '\'', false, true)
+	return quoteRuneWith(r, '\'', false, true)
 }
 
 // AppendQuoteRuneToGraphic appends a single-quoted Go character literal representing the rune,
 // as generated by QuoteRuneToGraphic, to dst and returns the extended buffer.
 func AppendQuoteRuneToGraphic(dst []byte, r rune) []byte {
-	return append(dst, QuoteRuneToGraphic(r)...)
+	return appendQuotedRuneWith(dst, r, '\'', false, true)
 }
 
 // CanBackquote reports whether the string s can be represented
@@ -331,7 +347,7 @@ func UnquoteChar(s string, quote byte) (value rune, multibyte bool, tail string,
 // that s quotes.  (If s is single-quoted, it would be a Go
 // character literal; Unquote returns the corresponding
 // one-character string.)
-func Unquote(s string) (t string, err error) {
+func Unquote(s string) (string, error) {
 	n := len(s)
 	if n < 2 {
 		return "", ErrSyntax
diff --git a/libgo/go/strconv/quote_test.go b/libgo/go/strconv/quote_test.go
index 3e8ec2c98f3..10735e316c7 100644
--- a/libgo/go/strconv/quote_test.go
+++ b/libgo/go/strconv/quote_test.go
@@ -89,6 +89,34 @@ func TestQuoteToGraphic(t *testing.T) {
 	}
 }
 
+func BenchmarkQuote(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Quote("\a\b\f\r\n\t\v\a\b\f\r\n\t\v\a\b\f\r\n\t\v")
+	}
+}
+
+func BenchmarkQuoteRune(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		QuoteRune('\a')
+	}
+}
+
+var benchQuoteBuf []byte
+
+func BenchmarkAppendQuote(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		benchQuoteBuf = AppendQuote(benchQuoteBuf[:0], "\a\b\f\r\n\t\v\a\b\f\r\n\t\v\a\b\f\r\n\t\v")
+	}
+}
+
+var benchQuoteRuneBuf []byte
+
+func BenchmarkAppendQuoteRune(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		benchQuoteRuneBuf = AppendQuoteRune(benchQuoteRuneBuf[:0], '\a')
+	}
+}
+
 type quoteRuneTest struct {
 	in      rune
 	out     string
diff --git a/libgo/go/strings/compare.go b/libgo/go/strings/compare.go
index b84dddea74e..1fe6b8d89a3 100644
--- a/libgo/go/strings/compare.go
+++ b/libgo/go/strings/compare.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/strings/compare_test.go b/libgo/go/strings/compare_test.go
index 68fc88e1431..bc12e421b0d 100644
--- a/libgo/go/strings/compare_test.go
+++ b/libgo/go/strings/compare_test.go
@@ -56,7 +56,7 @@ func TestCompareStrings(t *testing.T) {
 	a := make([]byte, n+1)
 	b := make([]byte, n+1)
 	for len := 0; len < 128; len++ {
-		// randomish but deterministic data.  No 0 or 255.
+		// randomish but deterministic data. No 0 or 255.
 		for i := 0; i < len; i++ {
 			a[i] = byte(1 + 31*i%254)
 			b[i] = byte(1 + 31*i%254)
diff --git a/libgo/go/strings/reader.go b/libgo/go/strings/reader.go
index 7a872fbcb08..6c1a5064c0d 100644
--- a/libgo/go/strings/reader.go
+++ b/libgo/go/strings/reader.go
@@ -35,9 +35,6 @@ func (r *Reader) Len() int {
 func (r *Reader) Size() int64 { return int64(len(r.s)) }
 
 func (r *Reader) Read(b []byte) (n int, err error) {
-	if len(b) == 0 {
-		return 0, nil
-	}
 	if r.i >= int64(len(r.s)) {
 		return 0, io.EOF
 	}
@@ -62,14 +59,14 @@ func (r *Reader) ReadAt(b []byte, off int64) (n int, err error) {
 	return
 }
 
-func (r *Reader) ReadByte() (b byte, err error) {
+func (r *Reader) ReadByte() (byte, error) {
 	r.prevRune = -1
 	if r.i >= int64(len(r.s)) {
 		return 0, io.EOF
 	}
-	b = r.s[r.i]
+	b := r.s[r.i]
 	r.i++
-	return
+	return b, nil
 }
 
 func (r *Reader) UnreadByte() error {
@@ -110,11 +107,11 @@ func (r *Reader) Seek(offset int64, whence int) (int64, error) {
 	r.prevRune = -1
 	var abs int64
 	switch whence {
-	case 0:
+	case io.SeekStart:
 		abs = offset
-	case 1:
-		abs = int64(r.i) + offset
-	case 2:
+	case io.SeekCurrent:
+		abs = r.i + offset
+	case io.SeekEnd:
 		abs = int64(len(r.s)) + offset
 	default:
 		return 0, errors.New("strings.Reader.Seek: invalid whence")
@@ -145,6 +142,9 @@ func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	return
 }
 
+// Reset resets the Reader to be reading from s.
+func (r *Reader) Reset(s string) { *r = Reader{s, 0, -1} }
+
 // NewReader returns a new Reader reading from s.
 // It is similar to bytes.NewBufferString but more efficient and read-only.
 func NewReader(s string) *Reader { return &Reader{s, 0, -1} }
diff --git a/libgo/go/strings/reader_test.go b/libgo/go/strings/reader_test.go
index 5003a37be48..bf40eb1a31e 100644
--- a/libgo/go/strings/reader_test.go
+++ b/libgo/go/strings/reader_test.go
@@ -9,7 +9,6 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"os"
 	"strings"
 	"sync"
 	"testing"
@@ -23,17 +22,18 @@ func TestReader(t *testing.T) {
 		n       int
 		want    string
 		wantpos int64
+		readerr error
 		seekerr string
 	}{
-		{seek: os.SEEK_SET, off: 0, n: 20, want: "0123456789"},
-		{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
-		{seek: os.SEEK_SET, off: -1, seekerr: "strings.Reader.Seek: negative position"},
-		{seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
-		{seek: os.SEEK_SET, n: 5, want: "01234"},
-		{seek: os.SEEK_CUR, n: 5, want: "56789"},
-		{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
+		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
+		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
+		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
+		{seek: io.SeekStart, off: -1, seekerr: "strings.Reader.Seek: negative position"},
+		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},
+		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1, readerr: io.EOF},
+		{seek: io.SeekStart, n: 5, want: "01234"},
+		{seek: io.SeekCurrent, n: 5, want: "56789"},
+		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
 	}
 
 	for i, tt := range tests {
@@ -51,8 +51,8 @@ func TestReader(t *testing.T) {
 		}
 		buf := make([]byte, tt.n)
 		n, err := r.Read(buf)
-		if err != nil {
-			t.Errorf("%d. read = %v", i, err)
+		if err != tt.readerr {
+			t.Errorf("%d. read = %v; want %v", i, err, tt.readerr)
 			continue
 		}
 		got := string(buf[:n])
@@ -64,7 +64,7 @@ func TestReader(t *testing.T) {
 
 func TestReadAfterBigSeek(t *testing.T) {
 	r := strings.NewReader("0123456789")
-	if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+	if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
 		t.Fatal(err)
 	}
 	if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
@@ -170,3 +170,23 @@ func TestReaderLenSize(t *testing.T) {
 		t.Errorf("Size = %d; want 3", r.Size())
 	}
 }
+
+func TestReaderReset(t *testing.T) {
+	r := strings.NewReader("世界")
+	if _, _, err := r.ReadRune(); err != nil {
+		t.Errorf("ReadRune: unexpected error: %v", err)
+	}
+
+	const want = "abcdef"
+	r.Reset(want)
+	if err := r.UnreadRune(); err == nil {
+		t.Errorf("UnreadRune: expected error, got nil")
+	}
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Errorf("ReadAll: unexpected error: %v", err)
+	}
+	if got := string(buf); got != want {
+		t.Errorf("ReadAll: got %q, want %q", got, want)
+	}
+}
diff --git a/libgo/go/strings/strings.go b/libgo/go/strings/strings.go
index 37d5647ffd6..919e8c8354e 100644
--- a/libgo/go/strings/strings.go
+++ b/libgo/go/strings/strings.go
@@ -12,32 +12,25 @@ import (
 	"unicode/utf8"
 )
 
-// explode splits s into an array of UTF-8 sequences, one per Unicode character (still strings) up to a maximum of n (n < 0 means no limit).
-// Invalid UTF-8 sequences become correct encodings of U+FFF8.
+// explode splits s into a slice of UTF-8 strings,
+// one string per Unicode character up to a maximum of n (n < 0 means no limit).
+// Invalid UTF-8 sequences become correct encodings of U+FFFD.
 func explode(s string, n int) []string {
-	if n == 0 {
-		return nil
-	}
 	l := utf8.RuneCountInString(s)
-	if n <= 0 || n > l {
+	if n < 0 || n > l {
 		n = l
 	}
 	a := make([]string, n)
-	var size int
-	var ch rune
-	i, cur := 0, 0
-	for ; i+1 < n; i++ {
-		ch, size = utf8.DecodeRuneInString(s[cur:])
+	for i := 0; i < n-1; i++ {
+		ch, size := utf8.DecodeRuneInString(s)
+		a[i] = s[:size]
+		s = s[size:]
 		if ch == utf8.RuneError {
 			a[i] = string(utf8.RuneError)
-		} else {
-			a[i] = s[cur : cur+size]
 		}
-		cur += size
 	}
-	// add the rest, if there is any
-	if cur < len(s) {
-		a[i] = s[cur:]
+	if n > 0 {
+		a[n-1] = s
 	}
 	return a
 }
@@ -346,7 +339,7 @@ func FieldsFunc(s string, f func(rune) bool) []string {
 	return a
 }
 
-// Join concatenates the elements of a to create a single string.   The separator string
+// Join concatenates the elements of a to create a single string. The separator string
 // sep is placed between elements in the resulting string.
 func Join(a []string, sep string) string {
 	if len(a) == 0 {
@@ -384,8 +377,8 @@ func HasSuffix(s, suffix string) bool {
 // dropped from the string with no replacement.
 func Map(mapping func(rune) rune, s string) string {
 	// In the worst case, the string can grow when mapped, making
-	// things unpleasant.  But it's so rare we barge in assuming it's
-	// fine.  It could also shrink but that falls out naturally.
+	// things unpleasant. But it's so rare we barge in assuming it's
+	// fine. It could also shrink but that falls out naturally.
 	maxbytes := len(s) // length of b
 	nbytes := 0        // number of bytes encoded in b
 	// The output buffer b is initialized on demand, the first
@@ -714,7 +707,7 @@ func EqualFold(s, t string) bool {
 			return false
 		}
 
-		// General case.  SimpleFold(x) returns the next equivalent rune > x
+		// General case. SimpleFold(x) returns the next equivalent rune > x
 		// or wraps around to smaller values.
 		r := unicode.SimpleFold(sr)
 		for r != sr && r < tr {
@@ -726,6 +719,6 @@ func EqualFold(s, t string) bool {
 		return false
 	}
 
-	// One string is empty.  Are both?
+	// One string is empty. Are both?
 	return s == t
 }
diff --git a/libgo/go/strings/strings_amd64.go b/libgo/go/strings/strings_amd64.go
index 376113f0a22..55bf2d2f6fc 100644
--- a/libgo/go/strings/strings_amd64.go
+++ b/libgo/go/strings/strings_amd64.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/strings/strings_decl.go b/libgo/go/strings/strings_decl.go
index 810a696af27..3bae8448c3d 100644
--- a/libgo/go/strings/strings_decl.go
+++ b/libgo/go/strings/strings_decl.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/strings/strings_generic.go b/libgo/go/strings/strings_generic.go
index 811cb803168..d356f50f877 100644
--- a/libgo/go/strings/strings_generic.go
+++ b/libgo/go/strings/strings_generic.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/strings/strings_test.go b/libgo/go/strings/strings_test.go
index 49f55fe38c7..fcef761da79 100644
--- a/libgo/go/strings/strings_test.go
+++ b/libgo/go/strings/strings_test.go
@@ -190,6 +190,43 @@ func TestLastIndexByte(t *testing.T) {
 	}
 }
 
+func simpleIndex(s, sep string) int {
+	n := len(sep)
+	for i := n; i <= len(s); i++ {
+		if s[i-n:i] == sep {
+			return i - n
+		}
+	}
+	return -1
+}
+
+func TestIndexRandom(t *testing.T) {
+	const chars = "abcdefghijklmnopqrstuvwxyz0123456789"
+	for times := 0; times < 10; times++ {
+		for strLen := 5 + rand.Intn(5); strLen < 140; strLen += 10 { // Arbitrary
+			s1 := make([]byte, strLen)
+			for i := range s1 {
+				s1[i] = chars[rand.Intn(len(chars))]
+			}
+			s := string(s1)
+			for i := 0; i < 50; i++ {
+				begin := rand.Intn(len(s) + 1)
+				end := begin + rand.Intn(len(s)+1-begin)
+				sep := s[begin:end]
+				if i%4 == 0 {
+					pos := rand.Intn(len(sep) + 1)
+					sep = sep[:pos] + "A" + sep[pos:]
+				}
+				want := simpleIndex(s, sep)
+				res := Index(s, sep)
+				if res != want {
+					t.Errorf("Index(%s,%s) = %d; want %d", s, sep, res, want)
+				}
+			}
+		}
+	}
+}
+
 var indexRuneTests = []struct {
 	s    string
 	rune rune
@@ -256,31 +293,6 @@ func BenchmarkIndexByte(b *testing.B) {
 	}
 }
 
-var explodetests = []struct {
-	s string
-	n int
-	a []string
-}{
-	{"", -1, []string{}},
-	{abcd, 4, []string{"a", "b", "c", "d"}},
-	{faces, 3, []string{"☺", "☻", "☹"}},
-	{abcd, 2, []string{"a", "bcd"}},
-}
-
-func TestExplode(t *testing.T) {
-	for _, tt := range explodetests {
-		a := SplitN(tt.s, "", tt.n)
-		if !eq(a, tt.a) {
-			t.Errorf("explode(%q, %d) = %v; want %v", tt.s, tt.n, a, tt.a)
-			continue
-		}
-		s := Join(a, "")
-		if s != tt.s {
-			t.Errorf(`Join(explode(%q, %d), "") = %q`, tt.s, tt.n, s)
-		}
-	}
-}
-
 type SplitTest struct {
 	s   string
 	sep string
@@ -289,19 +301,23 @@ type SplitTest struct {
 }
 
 var splittests = []SplitTest{
+	{"", "", -1, []string{}},
+	{abcd, "", 2, []string{"a", "bcd"}},
+	{abcd, "", 4, []string{"a", "b", "c", "d"}},
+	{abcd, "", -1, []string{"a", "b", "c", "d"}},
+	{faces, "", -1, []string{"☺", "☻", "☹"}},
+	{faces, "", 3, []string{"☺", "☻", "☹"}},
+	{faces, "", 17, []string{"☺", "☻", "☹"}},
+	{"☺�☹", "", -1, []string{"☺", "�", "☹"}},
 	{abcd, "a", 0, nil},
 	{abcd, "a", -1, []string{"", "bcd"}},
 	{abcd, "z", -1, []string{"abcd"}},
-	{abcd, "", -1, []string{"a", "b", "c", "d"}},
 	{commas, ",", -1, []string{"1", "2", "3", "4"}},
 	{dots, "...", -1, []string{"1", ".2", ".3", ".4"}},
 	{faces, "☹", -1, []string{"☺☻", ""}},
 	{faces, "~", -1, []string{faces}},
-	{faces, "", -1, []string{"☺", "☻", "☹"}},
 	{"1 2 3 4", " ", 3, []string{"1", "2", "3 4"}},
 	{"1 2", " ", 3, []string{"1", "2"}},
-	{"123", "", 2, []string{"1", "23"}},
-	{"123", "", 17, []string{"1", "2", "3"}},
 }
 
 func TestSplit(t *testing.T) {
@@ -492,7 +508,7 @@ func rot13(r rune) rune {
 func TestMap(t *testing.T) {
 	// Run a couple of awful growth/shrinkage tests
 	a := tenRunes('a')
-	// 1.  Grow.  This triggers two reallocations in Map.
+	// 1.  Grow. This triggers two reallocations in Map.
 	maxRune := func(rune) rune { return unicode.MaxRune }
 	m := Map(maxRune, a)
 	expect := tenRunes(unicode.MaxRune)
@@ -973,7 +989,7 @@ var UnreadRuneErrorTests = []struct {
 	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
 	{"ReadByte", func(r *Reader) { r.ReadByte() }},
 	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
-	{"Seek", func(r *Reader) { r.Seek(0, 1) }},
+	{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
 	{"WriteTo", func(r *Reader) { r.WriteTo(&bytes.Buffer{}) }},
 }
 
@@ -1057,6 +1073,70 @@ var ContainsTests = []struct {
 	{"abc", "bcd", false},
 	{"abc", "", true},
 	{"", "a", false},
+
+	// cases to cover code in runtime/asm_amd64.s:indexShortStr
+	// 2-byte needle
+	{"xxxxxx", "01", false},
+	{"01xxxx", "01", true},
+	{"xx01xx", "01", true},
+	{"xxxx01", "01", true},
+	{"01xxxxx"[1:], "01", false},
+	{"xxxxx01"[:6], "01", false},
+	// 3-byte needle
+	{"xxxxxxx", "012", false},
+	{"012xxxx", "012", true},
+	{"xx012xx", "012", true},
+	{"xxxx012", "012", true},
+	{"012xxxxx"[1:], "012", false},
+	{"xxxxx012"[:7], "012", false},
+	// 4-byte needle
+	{"xxxxxxxx", "0123", false},
+	{"0123xxxx", "0123", true},
+	{"xx0123xx", "0123", true},
+	{"xxxx0123", "0123", true},
+	{"0123xxxxx"[1:], "0123", false},
+	{"xxxxx0123"[:8], "0123", false},
+	// 5-7-byte needle
+	{"xxxxxxxxx", "01234", false},
+	{"01234xxxx", "01234", true},
+	{"xx01234xx", "01234", true},
+	{"xxxx01234", "01234", true},
+	{"01234xxxxx"[1:], "01234", false},
+	{"xxxxx01234"[:9], "01234", false},
+	// 8-byte needle
+	{"xxxxxxxxxxxx", "01234567", false},
+	{"01234567xxxx", "01234567", true},
+	{"xx01234567xx", "01234567", true},
+	{"xxxx01234567", "01234567", true},
+	{"01234567xxxxx"[1:], "01234567", false},
+	{"xxxxx01234567"[:12], "01234567", false},
+	// 9-15-byte needle
+	{"xxxxxxxxxxxxx", "012345678", false},
+	{"012345678xxxx", "012345678", true},
+	{"xx012345678xx", "012345678", true},
+	{"xxxx012345678", "012345678", true},
+	{"012345678xxxxx"[1:], "012345678", false},
+	{"xxxxx012345678"[:13], "012345678", false},
+	// 16-byte needle
+	{"xxxxxxxxxxxxxxxxxxxx", "0123456789ABCDEF", false},
+	{"0123456789ABCDEFxxxx", "0123456789ABCDEF", true},
+	{"xx0123456789ABCDEFxx", "0123456789ABCDEF", true},
+	{"xxxx0123456789ABCDEF", "0123456789ABCDEF", true},
+	{"0123456789ABCDEFxxxxx"[1:], "0123456789ABCDEF", false},
+	{"xxxxx0123456789ABCDEF"[:20], "0123456789ABCDEF", false},
+	// 17-31-byte needle
+	{"xxxxxxxxxxxxxxxxxxxxx", "0123456789ABCDEFG", false},
+	{"0123456789ABCDEFGxxxx", "0123456789ABCDEFG", true},
+	{"xx0123456789ABCDEFGxx", "0123456789ABCDEFG", true},
+	{"xxxx0123456789ABCDEFG", "0123456789ABCDEFG", true},
+	{"0123456789ABCDEFGxxxxx"[1:], "0123456789ABCDEFG", false},
+	{"xxxxx0123456789ABCDEFG"[:21], "0123456789ABCDEFG", false},
+
+	// partial match cases
+	{"xx01x", "012", false},                             // 3
+	{"xx0123x", "01234", false},                         // 5-7
+	{"xx01234567x", "012345678", false},                 // 9-15
+	{"xx0123456789ABCDEFx", "0123456789ABCDEFG", false}, // 17-31, issue 15679
 }
 
 func TestContains(t *testing.T) {
diff --git a/libgo/go/sync/atomic/64bit_arm.go b/libgo/go/sync/atomic/64bit_arm.go
index b98e60827e4..4ef11747bb5 100644
--- a/libgo/go/sync/atomic/64bit_arm.go
+++ b/libgo/go/sync/atomic/64bit_arm.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/sync/atomic/atomic_test.go b/libgo/go/sync/atomic/atomic_test.go
index 6dae0fd8e72..5a33d7fac0d 100644
--- a/libgo/go/sync/atomic/atomic_test.go
+++ b/libgo/go/sync/atomic/atomic_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -747,7 +747,7 @@ func TestStorePointer(t *testing.T) {
 // (Is the function atomic?)
 //
 // For each function, we write a "hammer" function that repeatedly
-// uses the atomic operation to add 1 to a value.  After running
+// uses the atomic operation to add 1 to a value. After running
 // multiple hammers in parallel, check that we end with the correct
 // total.
 // Swap can't add 1, so it uses a different scheme.
diff --git a/libgo/go/sync/atomic/doc.go b/libgo/go/sync/atomic/doc.go
index 10fb8c9177c..302ff43070a 100644
--- a/libgo/go/sync/atomic/doc.go
+++ b/libgo/go/sync/atomic/doc.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/sync/atomic/value.go b/libgo/go/sync/atomic/value.go
index ab3aa112854..30abf726344 100644
--- a/libgo/go/sync/atomic/value.go
+++ b/libgo/go/sync/atomic/value.go
@@ -12,7 +12,11 @@ import (
 // Values can be created as part of other data structures.
 // The zero value for a Value returns nil from Load.
 // Once Store has been called, a Value must not be copied.
+//
+// A Value must not be copied after first use.
 type Value struct {
+	noCopy noCopy
+
 	v interface{}
 }
 
@@ -83,3 +87,13 @@ func (v *Value) Store(x interface{}) {
 // Disable/enable preemption, implemented in runtime.
 func runtime_procPin()
 func runtime_procUnpin()
+
+// noCopy may be embedded into structs which must not be copied
+// after the first use.
+//
+// See https://github.com/golang/go/issues/8005#issuecomment-190753527
+// for details.
+type noCopy struct{}
+
+// Lock is a no-op used by -copylocks checker from `go vet`.
+func (*noCopy) Lock() {}
diff --git a/libgo/go/sync/atomic/value_test.go b/libgo/go/sync/atomic/value_test.go
index 382dc6854d1..fd90451dd83 100644
--- a/libgo/go/sync/atomic/value_test.go
+++ b/libgo/go/sync/atomic/value_test.go
@@ -86,6 +86,11 @@ func TestValueConcurrent(t *testing.T) {
 		{complex(0, 0), complex(1, 2), complex(3, 4), complex(5, 6)},
 	}
 	p := 4 * runtime.GOMAXPROCS(0)
+	N := int(1e5)
+	if testing.Short() {
+		p /= 2
+		N = 1e3
+	}
 	for _, test := range tests {
 		var v Value
 		done := make(chan bool)
@@ -93,7 +98,7 @@ func TestValueConcurrent(t *testing.T) {
 			go func() {
 				r := rand.New(rand.NewSource(rand.Int63()))
 			loop:
-				for j := 0; j < 1e5; j++ {
+				for j := 0; j < N; j++ {
 					x := test[r.Intn(len(test))]
 					v.Store(x)
 					x = v.Load()
diff --git a/libgo/go/sync/cond.go b/libgo/go/sync/cond.go
index 0aefcda9084..c070d9d84ef 100644
--- a/libgo/go/sync/cond.go
+++ b/libgo/go/sync/cond.go
@@ -5,7 +5,6 @@
 package sync
 
 import (
-	"internal/race"
 	"sync/atomic"
 	"unsafe"
 )
@@ -21,11 +20,12 @@ import (
 // A Cond can be created as part of other structures.
 // A Cond must not be copied after first use.
 type Cond struct {
+	noCopy noCopy
+
 	// L is held while observing or changing the condition
 	L Locker
 
-	sema    syncSema
-	waiters uint32 // number of waiters
+	notify  notifyList
 	checker copyChecker
 }
 
@@ -35,13 +35,13 @@ func NewCond(l Locker) *Cond {
 }
 
 // Wait atomically unlocks c.L and suspends execution
-// of the calling goroutine.  After later resuming execution,
-// Wait locks c.L before returning.  Unlike in other systems,
+// of the calling goroutine. After later resuming execution,
+// Wait locks c.L before returning. Unlike in other systems,
 // Wait cannot return unless awoken by Broadcast or Signal.
 //
 // Because c.L is not locked when Wait first resumes, the caller
 // typically cannot assume that the condition is true when
-// Wait returns.  Instead, the caller should Wait in a loop:
+// Wait returns. Instead, the caller should Wait in a loop:
 //
 //    c.L.Lock()
 //    for !condition() {
@@ -52,15 +52,9 @@ func NewCond(l Locker) *Cond {
 //
 func (c *Cond) Wait() {
 	c.checker.check()
-	if race.Enabled {
-		race.Disable()
-	}
-	atomic.AddUint32(&c.waiters, 1)
-	if race.Enabled {
-		race.Enable()
-	}
+	t := runtime_notifyListAdd(&c.notify)
 	c.L.Unlock()
-	runtime_Syncsemacquire(&c.sema)
+	runtime_notifyListWait(&c.notify, t)
 	c.L.Lock()
 }
 
@@ -69,7 +63,8 @@ func (c *Cond) Wait() {
 // It is allowed but not required for the caller to hold c.L
 // during the call.
 func (c *Cond) Signal() {
-	c.signalImpl(false)
+	c.checker.check()
+	runtime_notifyListNotifyOne(&c.notify)
 }
 
 // Broadcast wakes all goroutines waiting on c.
@@ -77,34 +72,8 @@ func (c *Cond) Signal() {
 // It is allowed but not required for the caller to hold c.L
 // during the call.
 func (c *Cond) Broadcast() {
-	c.signalImpl(true)
-}
-
-func (c *Cond) signalImpl(all bool) {
 	c.checker.check()
-	if race.Enabled {
-		race.Disable()
-	}
-	for {
-		old := atomic.LoadUint32(&c.waiters)
-		if old == 0 {
-			if race.Enabled {
-				race.Enable()
-			}
-			return
-		}
-		new := old - 1
-		if all {
-			new = 0
-		}
-		if atomic.CompareAndSwapUint32(&c.waiters, old, new) {
-			if race.Enabled {
-				race.Enable()
-			}
-			runtime_Syncsemrelease(&c.sema, old-new)
-			return
-		}
-	}
+	runtime_notifyListNotifyAll(&c.notify)
 }
 
 // copyChecker holds back pointer to itself to detect object copying.
@@ -117,3 +86,13 @@ func (c *copyChecker) check() {
 		panic("sync.Cond is copied")
 	}
 }
+
+// noCopy may be embedded into structs which must not be copied
+// after the first use.
+//
+// See https://github.com/golang/go/issues/8005#issuecomment-190753527
+// for details.
+type noCopy struct{}
+
+// Lock is a no-op used by -copylocks checker from `go vet`.
+func (*noCopy) Lock() {}
diff --git a/libgo/go/sync/cond_test.go b/libgo/go/sync/cond_test.go
index 467c80621de..7b0729571ce 100644
--- a/libgo/go/sync/cond_test.go
+++ b/libgo/go/sync/cond_test.go
@@ -8,6 +8,7 @@ import (
 
 	"runtime"
 	"testing"
+	"time"
 )
 
 func TestCondSignal(t *testing.T) {
@@ -183,6 +184,64 @@ func TestRace(t *testing.T) {
 	<-done
 }
 
+func TestCondSignalStealing(t *testing.T) {
+	for iters := 0; iters < 1000; iters++ {
+		var m Mutex
+		cond := NewCond(&m)
+
+		// Start a waiter.
+		ch := make(chan struct{})
+		go func() {
+			m.Lock()
+			ch <- struct{}{}
+			cond.Wait()
+			m.Unlock()
+
+			ch <- struct{}{}
+		}()
+
+		<-ch
+		m.Lock()
+		m.Unlock()
+
+		// We know that the waiter is in the cond.Wait() call because we
+		// synchronized with it, then acquired/released the mutex it was
+		// holding when we synchronized.
+		//
+		// Start two goroutines that will race: one will broadcast on
+		// the cond var, the other will wait on it.
+		//
+		// The new waiter may or may not get notified, but the first one
+		// has to be notified.
+		done := false
+		go func() {
+			cond.Broadcast()
+		}()
+
+		go func() {
+			m.Lock()
+			for !done {
+				cond.Wait()
+			}
+			m.Unlock()
+		}()
+
+		// Check that the first waiter does get signaled.
+		select {
+		case <-ch:
+		case <-time.After(2 * time.Second):
+			t.Fatalf("First waiter didn't get broadcast.")
+		}
+
+		// Release the second waiter in case it didn't get the
+		// broadcast.
+		m.Lock()
+		done = true
+		m.Unlock()
+		cond.Broadcast()
+	}
+}
+
 func TestCondCopy(t *testing.T) {
 	defer func() {
 		err := recover()
diff --git a/libgo/go/sync/export_test.go b/libgo/go/sync/export_test.go
index fa5983a2d1e..6ed38dad89d 100644
--- a/libgo/go/sync/export_test.go
+++ b/libgo/go/sync/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/sync/mutex.go b/libgo/go/sync/mutex.go
index eb526144c52..90892793f0a 100644
--- a/libgo/go/sync/mutex.go
+++ b/libgo/go/sync/mutex.go
@@ -3,8 +3,8 @@
 // license that can be found in the LICENSE file.
 
 // Package sync provides basic synchronization primitives such as mutual
-// exclusion locks.  Other than the Once and WaitGroup types, most are intended
-// for use by low-level library routines.  Higher-level synchronization is
+// exclusion locks. Other than the Once and WaitGroup types, most are intended
+// for use by low-level library routines. Higher-level synchronization is
 // better done via channels and communication.
 //
 // Values containing the types defined in this package should not be copied.
@@ -19,6 +19,8 @@ import (
 // A Mutex is a mutual exclusion lock.
 // Mutexes can be created as part of other structures;
 // the zero value for a Mutex is an unlocked mutex.
+//
+// A Mutex must not be copied after first use.
 type Mutex struct {
 	state int32
 	sema  uint32
diff --git a/libgo/go/sync/once.go b/libgo/go/sync/once.go
index 10b42fddc2f..d8ef952ea54 100644
--- a/libgo/go/sync/once.go
+++ b/libgo/go/sync/once.go
@@ -18,10 +18,10 @@ type Once struct {
 // first time for this instance of Once. In other words, given
 // 	var once Once
 // if once.Do(f) is called multiple times, only the first call will invoke f,
-// even if f has a different value in each invocation.  A new instance of
+// even if f has a different value in each invocation. A new instance of
 // Once is required for each function to execute.
 //
-// Do is intended for initialization that must be run exactly once.  Since f
+// Do is intended for initialization that must be run exactly once. Since f
 // is niladic, it may be necessary to use a function literal to capture the
 // arguments to a function to be invoked by Do:
 // 	config.once.Do(func() { config.init(filename) })
diff --git a/libgo/go/sync/pool.go b/libgo/go/sync/pool.go
index 381af0bead5..bf29d88c5cb 100644
--- a/libgo/go/sync/pool.go
+++ b/libgo/go/sync/pool.go
@@ -40,7 +40,10 @@ import (
 // that scenario. It is more efficient to have such objects implement their own
 // free list.
 //
+// A Pool must not be copied after first use.
 type Pool struct {
+	noCopy noCopy
+
 	local     unsafe.Pointer // local fixed-size per-P pool, actual type is [P]poolLocal
 	localSize uintptr        // size of the local array
 
@@ -149,7 +152,7 @@ func (p *Pool) getSlow() (x interface{}) {
 func (p *Pool) pin() *poolLocal {
 	pid := runtime_procPin()
 	// In pinSlow we store to localSize and then to local, here we load in opposite order.
-	// Since we've disabled preemption, GC can not happen in between.
+	// Since we've disabled preemption, GC cannot happen in between.
 	// Thus here we must observe local at least as large localSize.
 	// We can observe a newer/larger local, it is fine (we must observe its zero-initialized-ness).
 	s := atomic.LoadUintptr(&p.localSize) // load-acquire
@@ -179,8 +182,8 @@ func (p *Pool) pinSlow() *poolLocal {
 	// If GOMAXPROCS changes between GCs, we re-allocate the array and lose the old one.
 	size := runtime.GOMAXPROCS(0)
 	local := make([]poolLocal, size)
-	atomic.StorePointer((*unsafe.Pointer)(&p.local), unsafe.Pointer(&local[0])) // store-release
-	atomic.StoreUintptr(&p.localSize, uintptr(size))                            // store-release
+	atomic.StorePointer(&p.local, unsafe.Pointer(&local[0])) // store-release
+	atomic.StoreUintptr(&p.localSize, uintptr(size))         // store-release
 	return &local[pid]
 }
 
diff --git a/libgo/go/sync/runtime.go b/libgo/go/sync/runtime.go
index c66d2deb4c8..96c56c85224 100644
--- a/libgo/go/sync/runtime.go
+++ b/libgo/go/sync/runtime.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -19,24 +19,33 @@ func runtime_Semacquire(s *uint32)
 // library and should not be used directly.
 func runtime_Semrelease(s *uint32)
 
-// Approximation of syncSema in runtime/sema.go.
-type syncSema struct {
-	lock uintptr
-	head unsafe.Pointer
-	tail unsafe.Pointer
+// Approximation of notifyList in runtime/sema.go. Size and alignment must
+// agree.
+type notifyList struct {
+	wait   uint32
+	notify uint32
+	lock   uintptr
+	head   unsafe.Pointer
+	tail   unsafe.Pointer
 }
 
-// Syncsemacquire waits for a pairing Syncsemrelease on the same semaphore s.
-func runtime_Syncsemacquire(s *syncSema)
+// See runtime/sema.go for documentation.
+func runtime_notifyListAdd(l *notifyList) uint32
 
-// Syncsemrelease waits for n pairing Syncsemacquire on the same semaphore s.
-func runtime_Syncsemrelease(s *syncSema, n uint32)
+// See runtime/sema.go for documentation.
+func runtime_notifyListWait(l *notifyList, t uint32)
 
-// Ensure that sync and runtime agree on size of syncSema.
-func runtime_Syncsemcheck(size uintptr)
+// See runtime/sema.go for documentation.
+func runtime_notifyListNotifyAll(l *notifyList)
+
+// See runtime/sema.go for documentation.
+func runtime_notifyListNotifyOne(l *notifyList)
+
+// Ensure that sync and runtime agree on size of notifyList.
+func runtime_notifyListCheck(size uintptr)
 func init() {
-	var s syncSema
-	runtime_Syncsemcheck(unsafe.Sizeof(s))
+	var n notifyList
+	runtime_notifyListCheck(unsafe.Sizeof(n))
 }
 
 // Active spinning runtime support.
diff --git a/libgo/go/sync/runtime_sema_test.go b/libgo/go/sync/runtime_sema_test.go
index 5b7dd3df3f0..a2382f46554 100644
--- a/libgo/go/sync/runtime_sema_test.go
+++ b/libgo/go/sync/runtime_sema_test.go
@@ -25,6 +25,9 @@ func BenchmarkSemaUncontended(b *testing.B) {
 }
 
 func benchmarkSema(b *testing.B, block, work bool) {
+	if b.N == 0 {
+		return
+	}
 	sem := uint32(0)
 	if block {
 		done := make(chan bool)
diff --git a/libgo/go/sync/rwmutex.go b/libgo/go/sync/rwmutex.go
index d438c93c88e..6734360e37a 100644
--- a/libgo/go/sync/rwmutex.go
+++ b/libgo/go/sync/rwmutex.go
@@ -11,11 +11,17 @@ import (
 )
 
 // An RWMutex is a reader/writer mutual exclusion lock.
-// The lock can be held by an arbitrary number of readers
-// or a single writer.
-// RWMutexes can be created as part of other
-// structures; the zero value for a RWMutex is
-// an unlocked mutex.
+// The lock can be held by an arbitrary number of readers or a single writer.
+// RWMutexes can be created as part of other structures;
+// the zero value for a RWMutex is an unlocked mutex.
+//
+// An RWMutex must not be copied after first use.
+//
+// If a goroutine holds a RWMutex for reading, it must not expect this or any
+// other goroutine to be able to also take the read lock until the first read
+// lock is released. In particular, this prohibits recursive read locking.
+// This is to ensure that the lock eventually becomes available;
+// a blocked Lock call excludes new readers from acquiring the lock.
 type RWMutex struct {
 	w           Mutex  // held if there are pending writers
 	writerSem   uint32 // semaphore for writers to wait for completing readers
@@ -71,9 +77,6 @@ func (rw *RWMutex) RUnlock() {
 // Lock locks rw for writing.
 // If the lock is already locked for reading or writing,
 // Lock blocks until the lock is available.
-// To ensure that the lock eventually becomes available,
-// a blocked Lock call excludes new readers from acquiring
-// the lock.
 func (rw *RWMutex) Lock() {
 	if race.Enabled {
 		_ = rw.w.state
@@ -94,11 +97,11 @@ func (rw *RWMutex) Lock() {
 	}
 }
 
-// Unlock unlocks rw for writing.  It is a run-time error if rw is
+// Unlock unlocks rw for writing. It is a run-time error if rw is
 // not locked for writing on entry to Unlock.
 //
 // As with Mutexes, a locked RWMutex is not associated with a particular
-// goroutine.  One goroutine may RLock (Lock) an RWMutex and then
+// goroutine. One goroutine may RLock (Lock) an RWMutex and then
 // arrange for another goroutine to RUnlock (Unlock) it.
 func (rw *RWMutex) Unlock() {
 	if race.Enabled {
diff --git a/libgo/go/sync/waitgroup.go b/libgo/go/sync/waitgroup.go
index c77fec306c0..b386e1fec2b 100644
--- a/libgo/go/sync/waitgroup.go
+++ b/libgo/go/sync/waitgroup.go
@@ -12,10 +12,14 @@ import (
 
 // A WaitGroup waits for a collection of goroutines to finish.
 // The main goroutine calls Add to set the number of
-// goroutines to wait for.  Then each of the goroutines
-// runs and calls Done when finished.  At the same time,
+// goroutines to wait for. Then each of the goroutines
+// runs and calls Done when finished. At the same time,
 // Wait can be used to block until all goroutines have finished.
+//
+// A WaitGroup must not be copied after first use.
 type WaitGroup struct {
+	noCopy noCopy
+
 	// 64-bit value: high 32 bits are counter, low 32 bits are waiter count.
 	// 64-bit atomic operations require 64-bit alignment, but 32-bit
 	// compilers do not ensure it. So we allocate 12 bytes and then use
diff --git a/libgo/go/syscall/bpf_bsd.go b/libgo/go/syscall/bpf_bsd.go
index cc6c1e77c50..8b587559edb 100644
--- a/libgo/go/syscall/bpf_bsd.go
+++ b/libgo/go/syscall/bpf_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,14 +12,17 @@ import (
 	"unsafe"
 )
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfStmt(code, k int) *BpfInsn {
 	return &BpfInsn{Code: uint16(code), K: uint32(k)}
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfJump(code, k, jt, jf int) *BpfInsn {
 	return &BpfInsn{Code: uint16(code), Jt: uint8(jt), Jf: uint8(jf), K: uint32(k)}
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfBuflen(fd int) (int, error) {
 	var l int
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGBLEN, uintptr(unsafe.Pointer(&l)))
@@ -29,6 +32,7 @@ func BpfBuflen(fd int) (int, error) {
 	return l, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfBuflen(fd, l int) (int, error) {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSBLEN, uintptr(unsafe.Pointer(&l)))
 	if err != 0 {
@@ -37,6 +41,7 @@ func SetBpfBuflen(fd, l int) (int, error) {
 	return l, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfDatalink(fd int) (int, error) {
 	var t int
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGDLT, uintptr(unsafe.Pointer(&t)))
@@ -46,6 +51,7 @@ func BpfDatalink(fd int) (int, error) {
 	return t, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfDatalink(fd, t int) (int, error) {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSDLT, uintptr(unsafe.Pointer(&t)))
 	if err != 0 {
@@ -54,6 +60,7 @@ func SetBpfDatalink(fd, t int) (int, error) {
 	return t, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfPromisc(fd, m int) error {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCPROMISC, uintptr(unsafe.Pointer(&m)))
 	if err != 0 {
@@ -62,6 +69,7 @@ func SetBpfPromisc(fd, m int) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func FlushBpf(fd int) error {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCFLUSH, 0)
 	if err != 0 {
@@ -75,6 +83,7 @@ type ivalue struct {
 	value int16
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfInterface(fd int, name string) (string, error) {
 	var iv ivalue
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGETIF, uintptr(unsafe.Pointer(&iv)))
@@ -84,6 +93,7 @@ func BpfInterface(fd int, name string) (string, error) {
 	return name, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfInterface(fd int, name string) error {
 	var iv ivalue
 	copy(iv.name[:], []byte(name))
@@ -94,6 +104,7 @@ func SetBpfInterface(fd int, name string) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfTimeout(fd int) (*Timeval, error) {
 	var tv Timeval
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGRTIMEOUT, uintptr(unsafe.Pointer(&tv)))
@@ -103,6 +114,7 @@ func BpfTimeout(fd int) (*Timeval, error) {
 	return &tv, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfTimeout(fd int, tv *Timeval) error {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSRTIMEOUT, uintptr(unsafe.Pointer(tv)))
 	if err != 0 {
@@ -111,6 +123,7 @@ func SetBpfTimeout(fd int, tv *Timeval) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfStats(fd int) (*BpfStat, error) {
 	var s BpfStat
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGSTATS, uintptr(unsafe.Pointer(&s)))
@@ -120,6 +133,7 @@ func BpfStats(fd int) (*BpfStat, error) {
 	return &s, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfImmediate(fd, m int) error {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCIMMEDIATE, uintptr(unsafe.Pointer(&m)))
 	if err != 0 {
@@ -128,6 +142,7 @@ func SetBpfImmediate(fd, m int) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpf(fd int, i []BpfInsn) error {
 	var p BpfProgram
 	p.Len = uint32(len(i))
@@ -139,6 +154,7 @@ func SetBpf(fd int, i []BpfInsn) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func CheckBpfVersion(fd int) error {
 	var v BpfVersion
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCVERSION, uintptr(unsafe.Pointer(&v)))
@@ -151,6 +167,7 @@ func CheckBpfVersion(fd int) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func BpfHeadercmpl(fd int) (int, error) {
 	var f int
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCGHDRCMPLT, uintptr(unsafe.Pointer(&f)))
@@ -160,6 +177,7 @@ func BpfHeadercmpl(fd int) (int, error) {
 	return f, nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetBpfHeadercmpl(fd, f int) error {
 	_, _, err := Syscall(SYS_IOCTL, uintptr(fd), BIOCSHDRCMPLT, uintptr(unsafe.Pointer(&f)))
 	if err != 0 {
diff --git a/libgo/go/syscall/creds_test.go b/libgo/go/syscall/creds_test.go
index b4a14ff4dd9..7c6ab1de1de 100644
--- a/libgo/go/syscall/creds_test.go
+++ b/libgo/go/syscall/creds_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/dir_plan9.go b/libgo/go/syscall/dir_plan9.go
index 697bf5499c3..15b267411cb 100644
--- a/libgo/go/syscall/dir_plan9.go
+++ b/libgo/go/syscall/dir_plan9.go
@@ -184,6 +184,7 @@ func gbit8(b []byte) (uint8, []byte) {
 }
 
 // gbit16 reads a 16-bit number in little-endian order from b and returns it with the remaining slice of b.
+//go:nosplit
 func gbit16(b []byte) (uint16, []byte) {
 	return uint16(b[0]) | uint16(b[1])<<8, b[2:]
 }
diff --git a/libgo/go/syscall/env_plan9.go b/libgo/go/syscall/env_plan9.go
index cbf7f410925..9a8a837e7d3 100644
--- a/libgo/go/syscall/env_plan9.go
+++ b/libgo/go/syscall/env_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/env_unix.go b/libgo/go/syscall/env_unix.go
index b5ded9c763c..5bf3336ce5a 100644
--- a/libgo/go/syscall/env_unix.go
+++ b/libgo/go/syscall/env_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/env_windows.go b/libgo/go/syscall/env_windows.go
index 1cb475428d7..3f751678ccb 100644
--- a/libgo/go/syscall/env_windows.go
+++ b/libgo/go/syscall/env_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/errors_plan9.go b/libgo/go/syscall/errors_plan9.go
index d7634c995ed..6952562c69c 100644
--- a/libgo/go/syscall/errors_plan9.go
+++ b/libgo/go/syscall/errors_plan9.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/exec_bsd.go b/libgo/go/syscall/exec_bsd.go
index 75126730f59..ab0750d0b6b 100644
--- a/libgo/go/syscall/exec_bsd.go
+++ b/libgo/go/syscall/exec_bsd.go
@@ -31,7 +31,7 @@ func runtime_AfterFork()
 // If a dup or exec fails, write the errno error to pipe.
 // (Pipe is close-on-exec so if exec succeeds, it will be closed.)
 // In the child, this function must not acquire any locks, because
-// they might have been locked at the time of the fork.  This means
+// they might have been locked at the time of the fork. This means
 // no rescheduling, no malloc calls, and no new stack segments.
 // For the same reason compiler does not race instrument it.
 // The calls to RawSyscall are okay because they are assembly
@@ -181,6 +181,9 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	}
 	for i = 0; i < len(fd); i++ {
 		if fd[i] >= 0 && fd[i] < int(i) {
+			if nextfd == pipe { // don't stomp on pipe
+				nextfd++
+			}
 			err1 = raw_dup2(fd[i], nextfd)
 			if err1 != 0 {
 				goto childerror
@@ -188,9 +191,6 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 			raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
 			fd[i] = nextfd
 			nextfd++
-			if nextfd == pipe { // don't stomp on pipe
-				nextfd++
-			}
 		}
 	}
 
diff --git a/libgo/go/syscall/exec_linux.go b/libgo/go/syscall/exec_linux.go
index 6987bc1f4ec..581a9886dcf 100644
--- a/libgo/go/syscall/exec_linux.go
+++ b/libgo/go/syscall/exec_linux.go
@@ -23,20 +23,21 @@ type SysProcIDMap struct {
 }
 
 type SysProcAttr struct {
-	Chroot      string         // Chroot.
-	Credential  *Credential    // Credential.
-	Ptrace      bool           // Enable tracing.
-	Setsid      bool           // Create session.
-	Setpgid     bool           // Set process group ID to Pgid, or, if Pgid == 0, to new pid.
-	Setctty     bool           // Set controlling terminal to fd Ctty (only meaningful if Setsid is set)
-	Noctty      bool           // Detach fd 0 from controlling terminal
-	Ctty        int            // Controlling TTY fd
-	Foreground  bool           // Place child's process group in foreground. (Implies Setpgid. Uses Ctty as fd of controlling TTY)
-	Pgid        int            // Child's process group ID if Setpgid.
-	Pdeathsig   Signal         // Signal that the process will get when its parent dies (Linux only)
-	Cloneflags  uintptr        // Flags for clone calls (Linux only)
-	UidMappings []SysProcIDMap // User ID mappings for user namespaces.
-	GidMappings []SysProcIDMap // Group ID mappings for user namespaces.
+	Chroot       string         // Chroot.
+	Credential   *Credential    // Credential.
+	Ptrace       bool           // Enable tracing.
+	Setsid       bool           // Create session.
+	Setpgid      bool           // Set process group ID to Pgid, or, if Pgid == 0, to new pid.
+	Setctty      bool           // Set controlling terminal to fd Ctty (only meaningful if Setsid is set)
+	Noctty       bool           // Detach fd 0 from controlling terminal
+	Ctty         int            // Controlling TTY fd
+	Foreground   bool           // Place child's process group in foreground. (Implies Setpgid. Uses Ctty as fd of controlling TTY)
+	Pgid         int            // Child's process group ID if Setpgid.
+	Pdeathsig    Signal         // Signal that the process will get when its parent dies (Linux only)
+	Cloneflags   uintptr        // Flags for clone calls (Linux only)
+	Unshareflags uintptr        // Flags for unshare calls (Linux only)
+	UidMappings  []SysProcIDMap // User ID mappings for user namespaces.
+	GidMappings  []SysProcIDMap // Group ID mappings for user namespaces.
 	// GidMappingsEnableSetgroups enabling setgroups syscall.
 	// If false, then setgroups syscall will be disabled for the child process.
 	// This parameter is no-op if GidMappings == nil. Otherwise for unprivileged
@@ -52,7 +53,7 @@ func runtime_AfterFork()
 // If a dup or exec fails, write the errno error to pipe.
 // (Pipe is close-on-exec so if exec succeeds, it will be closed.)
 // In the child, this function must not acquire any locks, because
-// they might have been locked at the time of the fork.  This means
+// they might have been locked at the time of the fork. This means
 // no rescheduling, no malloc calls, and no new stack segments.
 // For the same reason compiler does not race instrument it.
 // The calls to RawSyscall are okay because they are assembly
@@ -192,11 +193,25 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 		}
 	}
 
+	// Unshare
+	if sys.Unshareflags != 0 {
+		_, _, err1 = RawSyscall(SYS_UNSHARE, sys.Unshareflags, 0, 0)
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
 	// User and groups
 	if cred := sys.Credential; cred != nil {
 		ngroups := len(cred.Groups)
+		var groups unsafe.Pointer
 		if ngroups > 0 {
-			groups := unsafe.Pointer(&cred.Groups[0])
+			groups = unsafe.Pointer(&cred.Groups[0])
+		}
+		// Don't call setgroups in case of user namespace, gid mappings
+		// and disabled setgroups, because otherwise unprivileged user namespace
+		// will fail with any non-empty SysProcAttr.Credential.
+		if !(sys.GidMappings != nil && !sys.GidMappingsEnableSetgroups && ngroups == 0) {
 			err1 = raw_setgroups(ngroups, groups)
 			if err1 != 0 {
 				goto childerror
@@ -253,6 +268,9 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	}
 	for i = 0; i < len(fd); i++ {
 		if fd[i] >= 0 && fd[i] < int(i) {
+			if nextfd == pipe { // don't stomp on pipe
+				nextfd++
+			}
 			err1 = raw_dup2(fd[i], nextfd)
 			if err1 != 0 {
 				goto childerror
@@ -260,9 +278,6 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 			raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
 			fd[i] = nextfd
 			nextfd++
-			if nextfd == pipe { // don't stomp on pipe
-				nextfd++
-			}
 		}
 	}
 
diff --git a/libgo/go/syscall/exec_linux_test.go b/libgo/go/syscall/exec_linux_test.go
index 6d319411840..aaffa067bcf 100644
--- a/libgo/go/syscall/exec_linux_test.go
+++ b/libgo/go/syscall/exec_linux_test.go
@@ -26,11 +26,14 @@ func isChrooted(t *testing.T) bool {
 	return root.Sys().(*syscall.Stat_t).Ino != 2
 }
 
-func whoamiCmd(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd {
+func checkUserNS(t *testing.T) {
 	if _, err := os.Stat("/proc/self/ns/user"); err != nil {
 		if os.IsNotExist(err) {
 			t.Skip("kernel doesn't support user namespaces")
 		}
+		if os.IsPermission(err) {
+			t.Skip("unable to test user namespaces due to permissions")
+		}
 		t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
 	}
 	if isChrooted(t) {
@@ -53,6 +56,10 @@ func whoamiCmd(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd {
 	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
 		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
 	}
+}
+
+func whoamiCmd(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd {
+	checkUserNS(t)
 	cmd := exec.Command("whoami")
 	cmd.SysProcAttr = &syscall.SysProcAttr{
 		Cloneflags: syscall.CLONE_NEWUSER,
@@ -122,3 +129,121 @@ func TestEmptyCredGroupsDisableSetgroups(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestUnshare(t *testing.T) {
+	// Make sure we are running as root so we have permissions to use unshare
+	// and create a network namespace.
+	if os.Getuid() != 0 {
+		t.Skip("kernel prohibits unshare in unprivileged process, unless using user namespace")
+	}
+
+	// When running under the Go continuous build, skip tests for
+	// now when under Kubernetes. (where things are root but not quite)
+	// Both of these are our own environment variables.
+	// See Issue 12815.
+	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
+		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
+	}
+
+	path := "/proc/net/dev"
+	if _, err := os.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			t.Skip("kernel doesn't support proc filesystem")
+		}
+		if os.IsPermission(err) {
+			t.Skip("unable to test proc filesystem due to permissions")
+		}
+		t.Fatal(err)
+	}
+	if _, err := os.Stat("/proc/self/ns/net"); err != nil {
+		if os.IsNotExist(err) {
+			t.Skip("kernel doesn't support net namespace")
+		}
+		t.Fatal(err)
+	}
+
+	cmd := exec.Command("cat", path)
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Unshareflags: syscall.CLONE_NEWNET,
+	}
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
+	}
+
+	// Check there is only the local network interface
+	sout := strings.TrimSpace(string(out))
+	if !strings.Contains(sout, "lo:") {
+		t.Fatalf("Expected lo network interface to exist, got %s", sout)
+	}
+
+	lines := strings.Split(sout, "\n")
+	if len(lines) != 3 {
+		t.Fatalf("Expected 3 lines of output, got %d", len(lines))
+	}
+}
+
+func TestGroupCleanup(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("we need root for credential")
+	}
+	cmd := exec.Command("id")
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Credential: &syscall.Credential{
+			Uid: 0,
+			Gid: 0,
+		},
+	}
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
+	}
+	strOut := strings.TrimSpace(string(out))
+	expected := "uid=0(root) gid=0(root) groups=0(root)"
+	// Just check prefix because some distros reportedly output a
+	// context parameter; see https://golang.org/issue/16224.
+	if !strings.HasPrefix(strOut, expected) {
+		t.Errorf("id command output: %q, expected prefix: %q", strOut, expected)
+	}
+}
+
+func TestGroupCleanupUserNamespace(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("we need root for credential")
+	}
+	checkUserNS(t)
+	cmd := exec.Command("id")
+	uid, gid := os.Getuid(), os.Getgid()
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Cloneflags: syscall.CLONE_NEWUSER,
+		Credential: &syscall.Credential{
+			Uid: uint32(uid),
+			Gid: uint32(gid),
+		},
+		UidMappings: []syscall.SysProcIDMap{
+			{ContainerID: 0, HostID: uid, Size: 1},
+		},
+		GidMappings: []syscall.SysProcIDMap{
+			{ContainerID: 0, HostID: gid, Size: 1},
+		},
+	}
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
+	}
+	strOut := strings.TrimSpace(string(out))
+
+	// Strings we've seen in the wild.
+	expected := []string{
+		"uid=0(root) gid=0(root) groups=0(root)",
+		"uid=0(root) gid=0(root) groups=0(root),65534(nobody)",
+		"uid=0(root) gid=0(root) groups=0(root),65534(nogroup)",
+		"uid=0(root) gid=0(root) groups=0(root),65534",
+	}
+	for _, e := range expected {
+		if strOut == e {
+			return
+		}
+	}
+	t.Errorf("id command output: %q, expected one of %q", strOut, expected)
+}
diff --git a/libgo/go/syscall/exec_unix.go b/libgo/go/syscall/exec_unix.go
index 3b772e6ddb5..3018b43d72e 100644
--- a/libgo/go/syscall/exec_unix.go
+++ b/libgo/go/syscall/exec_unix.go
@@ -68,31 +68,31 @@ import (
 // Lock synchronizing creation of new file descriptors with fork.
 //
 // We want the child in a fork/exec sequence to inherit only the
-// file descriptors we intend.  To do that, we mark all file
+// file descriptors we intend. To do that, we mark all file
 // descriptors close-on-exec and then, in the child, explicitly
 // unmark the ones we want the exec'ed program to keep.
 // Unix doesn't make this easy: there is, in general, no way to
-// allocate a new file descriptor close-on-exec.  Instead you
+// allocate a new file descriptor close-on-exec. Instead you
 // have to allocate the descriptor and then mark it close-on-exec.
 // If a fork happens between those two events, the child's exec
 // will inherit an unwanted file descriptor.
 //
 // This lock solves that race: the create new fd/mark close-on-exec
 // operation is done holding ForkLock for reading, and the fork itself
-// is done holding ForkLock for writing.  At least, that's the idea.
+// is done holding ForkLock for writing. At least, that's the idea.
 // There are some complications.
 //
 // Some system calls that create new file descriptors can block
 // for arbitrarily long times: open on a hung NFS server or named
-// pipe, accept on a socket, and so on.  We can't reasonably grab
+// pipe, accept on a socket, and so on. We can't reasonably grab
 // the lock across those operations.
 //
 // It is worse to inherit some file descriptors than others.
 // If a non-malicious child accidentally inherits an open ordinary file,
-// that's not a big deal.  On the other hand, if a long-lived child
+// that's not a big deal. On the other hand, if a long-lived child
 // accidentally inherits the write end of a pipe, then the reader
 // of that pipe will not see EOF until that child exits, potentially
-// causing the parent program to hang.  This is a common problem
+// causing the parent program to hang. This is a common problem
 // in threaded C programs that use popen.
 //
 // Luckily, the file descriptors that are most important not to
@@ -102,13 +102,13 @@ import (
 // The rules for which file descriptor-creating operations use the
 // ForkLock are as follows:
 //
-// 1) Pipe.    Does not block.  Use the ForkLock.
-// 2) Socket.  Does not block.  Use the ForkLock.
-// 3) Accept.  If using non-blocking mode, use the ForkLock.
+// 1) Pipe. Does not block. Use the ForkLock.
+// 2) Socket. Does not block. Use the ForkLock.
+// 3) Accept. If using non-blocking mode, use the ForkLock.
 //             Otherwise, live with the race.
-// 4) Open.    Can block.  Use O_CLOEXEC if available (GNU/Linux).
+// 4) Open. Can block. Use O_CLOEXEC if available (GNU/Linux).
 //             Otherwise, live with the race.
-// 5) Dup.     Does not block.  Use the ForkLock.
+// 5) Dup. Does not block. Use the ForkLock.
 //             On GNU/Linux, could use fcntl F_DUPFD_CLOEXEC
 //             instead of the ForkLock, but only for dup(fd, -1).
 
@@ -154,7 +154,7 @@ func SetNonblock(fd int, nonblocking bool) (err error) {
 	if nonblocking {
 		flag |= O_NONBLOCK
 	} else {
-		flag &= ^O_NONBLOCK
+		flag &^= O_NONBLOCK
 	}
 	_, err = fcntl(fd, F_SETFL, flag)
 	return err
diff --git a/libgo/go/syscall/export_test.go b/libgo/go/syscall/export_test.go
index c9774622c87..55c09e667e2 100644
--- a/libgo/go/syscall/export_test.go
+++ b/libgo/go/syscall/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/libcall_posix.go b/libgo/go/syscall/libcall_posix.go
index d3580a1bc0c..84bbeda4127 100644
--- a/libgo/go/syscall/libcall_posix.go
+++ b/libgo/go/syscall/libcall_posix.go
@@ -399,3 +399,17 @@ func NsecToTimeval(nsec int64) (tv Timeval) {
 
 //sys	Tcsetattr(fd int, actions int, p *Termios) (err error)
 //tcsetattr(fd _C_int, actions _C_int, p *Termios) _C_int
+
+//sys	sysconf(name int) (ret int64, err error)
+//sysconf(name _C_int) _C_long
+
+func Sysconf(name int) (ret int64, err error) {
+	// If an option is not available, sysconf returns -1 without
+	// changing errno.  Detect this case and return err == nil.
+	SetErrno(0)
+	ret, err = sysconf(name)
+	if err == Errno(0) {
+		err = nil
+	}
+	return ret, err
+}
diff --git a/libgo/go/syscall/lsf_linux.go b/libgo/go/syscall/lsf_linux.go
index 48ba191c6da..16b702a9840 100644
--- a/libgo/go/syscall/lsf_linux.go
+++ b/libgo/go/syscall/lsf_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -10,14 +10,17 @@ import (
 	"unsafe"
 )
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func LsfStmt(code, k int) *SockFilter {
 	return &SockFilter{Code: uint16(code), K: uint32(k)}
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func LsfJump(code, k, jt, jf int) *SockFilter {
 	return &SockFilter{Code: uint16(code), Jt: uint8(jt), Jf: uint8(jf), K: uint32(k)}
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func LsfSocket(ifindex, proto int) (int, error) {
 	var lsall SockaddrLinklayer
 	s, e := Socket(AF_PACKET, SOCK_RAW, proto)
@@ -41,6 +44,7 @@ type iflags struct {
 	flags uint16
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func SetLsfPromisc(name string, m bool) error {
 	s, e := Socket(AF_INET, SOCK_DGRAM, 0)
 	if e != nil {
@@ -56,7 +60,7 @@ func SetLsfPromisc(name string, m bool) error {
 	if m {
 		ifl.flags |= uint16(IFF_PROMISC)
 	} else {
-		ifl.flags &= ^uint16(IFF_PROMISC)
+		ifl.flags &^= uint16(IFF_PROMISC)
 	}
 	_, _, ep = Syscall(SYS_IOCTL, uintptr(s), SIOCSIFFLAGS, uintptr(unsafe.Pointer(&ifl)))
 	if ep != 0 {
@@ -65,6 +69,7 @@ func SetLsfPromisc(name string, m bool) error {
 	return nil
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func AttachLsf(fd int, i []SockFilter) error {
 	var p SockFprog
 	p.Len = uint16(len(i))
@@ -72,6 +77,7 @@ func AttachLsf(fd int, i []SockFilter) error {
 	return setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, unsafe.Pointer(&p), Socklen_t(unsafe.Sizeof(p)))
 }
 
+// Deprecated: Use golang.org/x/net/bpf instead.
 func DetachLsf(fd int) error {
 	var dummy int
 	return setsockopt(fd, SOL_SOCKET, SO_DETACH_FILTER, unsafe.Pointer(&dummy), Socklen_t(unsafe.Sizeof(dummy)))
diff --git a/libgo/go/syscall/msan.go b/libgo/go/syscall/msan.go
index edd8d1ebd56..baaad6df984 100644
--- a/libgo/go/syscall/msan.go
+++ b/libgo/go/syscall/msan.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/msan0.go b/libgo/go/syscall/msan0.go
index 7617494e86d..ff10be9d25d 100644
--- a/libgo/go/syscall/msan0.go
+++ b/libgo/go/syscall/msan0.go
@@ -1,4 +1,4 @@
-// Copyright 2015 The Go Authors.  All rights reserved.
+// Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/netlink_linux.go b/libgo/go/syscall/netlink_linux.go
index 1b73dce8274..26b30403a1a 100644
--- a/libgo/go/syscall/netlink_linux.go
+++ b/libgo/go/syscall/netlink_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/route_bsd.go b/libgo/go/syscall/route_bsd.go
index c635a1385e2..b364eeaba5d 100644
--- a/libgo/go/syscall/route_bsd.go
+++ b/libgo/go/syscall/route_bsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -138,7 +138,7 @@ func parseNetworkLayerAddr(b []byte, family byte) (Sockaddr, error) {
 	//
 	// - The kernel form appends leading bytes to the prefix field
 	//   to make the <length, prefix> tuple to be conformed with
-	//   the routing messeage boundary
+	//   the routing message boundary
 	l := int(rsaAlignOf(int(b[0])))
 	if len(b) < l {
 		return nil, EINVAL
@@ -176,6 +176,8 @@ func parseNetworkLayerAddr(b []byte, family byte) (Sockaddr, error) {
 // RouteRIB returns routing information base, as known as RIB,
 // which consists of network facility information, states and
 // parameters.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 func RouteRIB(facility, param int) ([]byte, error) {
 	mib := []_C_int{CTL_NET, AF_ROUTE, 0, 0, _C_int(facility), _C_int(param)}
 	// Find size.
@@ -194,6 +196,8 @@ func RouteRIB(facility, param int) ([]byte, error) {
 }
 
 // RoutingMessage represents a routing message.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type RoutingMessage interface {
 	sockaddr() ([]Sockaddr, error)
 }
@@ -208,6 +212,8 @@ type anyMessage struct {
 
 // RouteMessage represents a routing message containing routing
 // entries.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type RouteMessage struct {
 	Header RtMsghdr
 	Data   []byte
@@ -252,6 +258,8 @@ func (m *RouteMessage) sockaddr() ([]Sockaddr, error) {
 
 // InterfaceMessage represents a routing message containing
 // network interface entries.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceMessage struct {
 	Header IfMsghdr
 	Data   []byte
@@ -272,6 +280,8 @@ func (m *InterfaceMessage) sockaddr() ([]Sockaddr, error) {
 
 // InterfaceAddrMessage represents a routing message containing
 // network interface address entries.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceAddrMessage struct {
 	Header IfaMsghdr
 	Data   []byte
@@ -316,6 +326,8 @@ func (m *InterfaceAddrMessage) sockaddr() ([]Sockaddr, error) {
 
 // ParseRoutingMessage parses b as routing messages and returns the
 // slice containing the RoutingMessage interfaces.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 func ParseRoutingMessage(b []byte) (msgs []RoutingMessage, err error) {
 	nmsgs, nskips := 0, 0
 	for len(b) >= anyMessageLen {
@@ -341,6 +353,8 @@ func ParseRoutingMessage(b []byte) (msgs []RoutingMessage, err error) {
 
 // ParseRoutingSockaddr parses msg's payload as raw sockaddrs and
 // returns the slice containing the Sockaddr interfaces.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 func ParseRoutingSockaddr(msg RoutingMessage) ([]Sockaddr, error) {
 	sas, err := msg.sockaddr()
 	if err != nil {
diff --git a/libgo/go/syscall/route_bsd_test.go b/libgo/go/syscall/route_bsd_test.go
deleted file mode 100644
index 74d11f9f0a5..00000000000
--- a/libgo/go/syscall/route_bsd_test.go
+++ /dev/null
@@ -1,260 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build darwin dragonfly freebsd netbsd openbsd
-
-package syscall_test
-
-import (
-	"fmt"
-	"net"
-	"os"
-	"syscall"
-	"testing"
-	"time"
-)
-
-func TestRouteRIB(t *testing.T) {
-	for _, facility := range []int{syscall.NET_RT_DUMP, syscall.NET_RT_IFLIST} {
-		for _, param := range []int{syscall.AF_UNSPEC, syscall.AF_INET, syscall.AF_INET6} {
-			var err error
-			var b []byte
-			// The VM allocator wrapper functions can
-			// return ENOMEM easily.
-			for i := 0; i < 3; i++ {
-				b, err = syscall.RouteRIB(facility, param)
-				if err != nil {
-					time.Sleep(5 * time.Millisecond)
-					continue
-				}
-				break
-			}
-			if err != nil {
-				t.Error(facility, param, err)
-				continue
-			}
-			msgs, err := syscall.ParseRoutingMessage(b)
-			if err != nil {
-				t.Error(facility, param, err)
-				continue
-			}
-			var ipv4loopback, ipv6loopback bool
-			for _, m := range msgs {
-				flags, err := parseRoutingMessageHeader(m)
-				if err != nil {
-					t.Error(err)
-					continue
-				}
-				sas, err := parseRoutingSockaddrs(m)
-				if err != nil {
-					t.Error(err)
-					continue
-				}
-				if flags&(syscall.RTA_DST|syscall.RTA_IFA) != 0 {
-					sa := sas[syscall.RTAX_DST]
-					if sa == nil {
-						sa = sas[syscall.RTAX_IFA]
-					}
-					switch sa := sa.(type) {
-					case *syscall.SockaddrInet4:
-						if net.IP(sa.Addr[:]).IsLoopback() {
-							ipv4loopback = true
-						}
-					case *syscall.SockaddrInet6:
-						if net.IP(sa.Addr[:]).IsLoopback() {
-							ipv6loopback = true
-						}
-					}
-				}
-				t.Log(facility, param, flags, sockaddrs(sas))
-			}
-			if param == syscall.AF_UNSPEC && len(msgs) > 0 && !ipv4loopback && !ipv6loopback {
-				t.Errorf("no loopback facility found: ipv4/ipv6=%v/%v, %v", ipv4loopback, ipv6loopback, len(msgs))
-				continue
-			}
-		}
-	}
-}
-
-func TestRouteMonitor(t *testing.T) {
-	if testing.Short() || os.Getuid() != 0 {
-		t.Skip("must be root")
-	}
-
-	s, err := syscall.Socket(syscall.AF_ROUTE, syscall.SOCK_RAW, syscall.AF_UNSPEC)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer syscall.Close(s)
-
-	tmo := time.After(30 * time.Second)
-	go func() {
-		b := make([]byte, os.Getpagesize())
-		for {
-			n, err := syscall.Read(s, b)
-			if err != nil {
-				return
-			}
-			msgs, err := syscall.ParseRoutingMessage(b[:n])
-			if err != nil {
-				t.Error(err)
-				return
-			}
-			for _, m := range msgs {
-				flags, err := parseRoutingMessageHeader(m)
-				if err != nil {
-					t.Error(err)
-					continue
-				}
-				sas, err := parseRoutingSockaddrs(m)
-				if err != nil {
-					t.Error(err)
-					continue
-				}
-				t.Log(flags, sockaddrs(sas))
-			}
-		}
-	}()
-	<-tmo
-}
-
-var parseInterfaceMessageTests = []*syscall.InterfaceMessage{
-	// with link-layer address
-	{
-		Header: syscall.IfMsghdr{Version: syscall.RTM_VERSION, Addrs: syscall.RTA_IFP},
-		Data: []uint8{
-			0x11, 0x12, 0x2, 0x0, 0x6, 0x3, 0x6, 0x0,
-			0x77, 0x6d, 0x31, 0x01, 0x23, 0x45, 0xab, 0xcd,
-			0xef, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
-		},
-	},
-	// without link-layer address
-	{
-		Header: syscall.IfMsghdr{Version: syscall.RTM_VERSION, Addrs: syscall.RTA_IFP},
-		Data: []uint8{
-			0xe, 0x12, 0x4, 0x0, 0xf5, 0x6, 0x0, 0x0,
-			0x70, 0x66, 0x6c, 0x6f, 0x67, 0x30, 0x0, 0x0,
-		},
-	},
-	// no data
-	{
-		Header: syscall.IfMsghdr{Version: syscall.RTM_VERSION, Addrs: syscall.RTA_IFP},
-		Data: []uint8{
-			0x8, 0xa, 0xb, 0xc, 0xd, 0x0, 0x0, 0x0,
-		},
-	},
-}
-
-func TestParseInterfaceMessage(t *testing.T) {
-	for i, tt := range parseInterfaceMessageTests {
-		if _, err := syscall.ParseRoutingSockaddr(tt); err != nil {
-			t.Errorf("#%d: %v", i, err)
-		}
-	}
-}
-
-type addrFamily byte
-
-func (f addrFamily) String() string {
-	switch f {
-	case syscall.AF_UNSPEC:
-		return "unspec"
-	case syscall.AF_LINK:
-		return "link"
-	case syscall.AF_INET:
-		return "inet4"
-	case syscall.AF_INET6:
-		return "inet6"
-	default:
-		return fmt.Sprintf("unknown %d", f)
-	}
-}
-
-type addrFlags uint32
-
-var addrFlagNames = [...]string{
-	"dst",
-	"gateway",
-	"netmask",
-	"genmask",
-	"ifp",
-	"ifa",
-	"author",
-	"brd",
-	"mpls1,tag,src", // sockaddr_mpls=dragonfly,netbsd, sockaddr_in/in6=openbsd
-	"mpls2,srcmask", // sockaddr_mpls=dragonfly, sockaddr_in/in6=openbsd
-	"mpls3,label",   // sockaddr_mpls=dragonfly, sockaddr_rtlabel=openbsd
-}
-
-func (f addrFlags) String() string {
-	var s string
-	for i, name := range addrFlagNames {
-		if f&(1<<uint(i)) != 0 {
-			if s != "" {
-				s += "|"
-			}
-			s += name
-		}
-	}
-	if s == "" {
-		return "<nil>"
-	}
-	return s
-}
-
-type sockaddrs []syscall.Sockaddr
-
-func (sas sockaddrs) String() string {
-	var s string
-	for _, sa := range sas {
-		if sa == nil {
-			continue
-		}
-		if len(s) > 0 {
-			s += " "
-		}
-		switch sa := sa.(type) {
-		case *syscall.SockaddrDatalink:
-			s += fmt.Sprintf("[%v/%v/%v t/n/a/s=%v/%v/%v/%v]", sa.Len, addrFamily(sa.Family), sa.Index, sa.Type, sa.Nlen, sa.Alen, sa.Slen)
-		case *syscall.SockaddrInet4:
-			s += fmt.Sprintf("%v", net.IP(sa.Addr[:]).To4())
-		case *syscall.SockaddrInet6:
-			s += fmt.Sprintf("%v", net.IP(sa.Addr[:]).To16())
-		}
-	}
-	if s == "" {
-		return "<nil>"
-	}
-	return s
-}
-
-func (sas sockaddrs) match(flags addrFlags) error {
-	var f addrFlags
-	family := syscall.AF_UNSPEC
-	for i := range sas {
-		if sas[i] != nil {
-			f |= 1 << uint(i)
-		}
-		switch sas[i].(type) {
-		case *syscall.SockaddrInet4:
-			if family == syscall.AF_UNSPEC {
-				family = syscall.AF_INET
-			}
-			if family != syscall.AF_INET {
-				return fmt.Errorf("got %v; want %v", sockaddrs(sas), family)
-			}
-		case *syscall.SockaddrInet6:
-			if family == syscall.AF_UNSPEC {
-				family = syscall.AF_INET6
-			}
-			if family != syscall.AF_INET6 {
-				return fmt.Errorf("got %v; want %v", sockaddrs(sas), family)
-			}
-		}
-	}
-	if f != flags {
-		return fmt.Errorf("got %v; want %v", f, flags)
-	}
-	return nil
-}
diff --git a/libgo/go/syscall/route_darwin.go b/libgo/go/syscall/route_darwin.go
index 89bca12f3e1..b0636ed07ce 100644
--- a/libgo/go/syscall/route_darwin.go
+++ b/libgo/go/syscall/route_darwin.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -26,6 +26,8 @@ func (any *anyMessage) toRoutingMessage(b []byte) RoutingMessage {
 
 // InterfaceMulticastAddrMessage represents a routing message
 // containing network interface address entries.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceMulticastAddrMessage struct {
 	Header IfmaMsghdr2
 	Data   []byte
diff --git a/libgo/go/syscall/route_dragonfly.go b/libgo/go/syscall/route_dragonfly.go
index 5226f7f2e4c..b562400be8b 100644
--- a/libgo/go/syscall/route_dragonfly.go
+++ b/libgo/go/syscall/route_dragonfly.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -31,6 +31,8 @@ func (any *anyMessage) toRoutingMessage(b []byte) RoutingMessage {
 
 // InterfaceAnnounceMessage represents a routing message containing
 // network interface arrival and departure information.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceAnnounceMessage struct {
 	Header IfAnnounceMsghdr
 }
@@ -39,6 +41,8 @@ func (m *InterfaceAnnounceMessage) sockaddr() ([]Sockaddr, error) { return nil,
 
 // InterfaceMulticastAddrMessage represents a routing message
 // containing network interface address entries.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceMulticastAddrMessage struct {
 	Header IfmaMsghdr
 	Data   []byte
diff --git a/libgo/go/syscall/route_freebsd.go b/libgo/go/syscall/route_freebsd.go
index 0e181038555..2c2de7474a4 100644
--- a/libgo/go/syscall/route_freebsd.go
+++ b/libgo/go/syscall/route_freebsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -53,6 +53,8 @@ func (any *anyMessage) toRoutingMessage(b []byte) RoutingMessage {
 
 // InterfaceAnnounceMessage represents a routing message containing
 // network interface arrival and departure information.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceAnnounceMessage struct {
 	Header IfAnnounceMsghdr
 }
@@ -61,6 +63,8 @@ func (m *InterfaceAnnounceMessage) sockaddr() ([]Sockaddr, error) { return nil,
 
 // InterfaceMulticastAddrMessage represents a routing message
 // containing network interface address entries.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceMulticastAddrMessage struct {
 	Header IfmaMsghdr
 	Data   []byte
diff --git a/libgo/go/syscall/route_ifma_test.go b/libgo/go/syscall/route_ifma_test.go
deleted file mode 100644
index af2b67dc244..00000000000
--- a/libgo/go/syscall/route_ifma_test.go
+++ /dev/null
@@ -1,74 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build darwin dragonfly freebsd
-
-package syscall_test
-
-import (
-	"fmt"
-	"syscall"
-)
-
-func parseRoutingMessageHeader(m syscall.RoutingMessage) (addrFlags, error) {
-	switch m := m.(type) {
-	case *syscall.RouteMessage:
-		errno := syscall.Errno(uintptr(m.Header.Errno))
-		if errno != 0 {
-			return 0, fmt.Errorf("%T: %v, %#v", m, errno, m.Header)
-		}
-		return addrFlags(m.Header.Addrs), nil
-	case *syscall.InterfaceMessage:
-		return addrFlags(m.Header.Addrs), nil
-	case *syscall.InterfaceAddrMessage:
-		return addrFlags(m.Header.Addrs), nil
-	case *syscall.InterfaceMulticastAddrMessage:
-		return addrFlags(m.Header.Addrs), nil
-	default:
-		panic(fmt.Sprintf("unknown routing message type: %T", m))
-	}
-}
-
-func parseRoutingSockaddrs(m syscall.RoutingMessage) ([]syscall.Sockaddr, error) {
-	switch m := m.(type) {
-	case *syscall.RouteMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	case *syscall.InterfaceMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	case *syscall.InterfaceAddrMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	case *syscall.InterfaceMulticastAddrMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	default:
-		panic(fmt.Sprintf("unknown routing message type: %T", m))
-	}
-}
diff --git a/libgo/go/syscall/route_netbsd.go b/libgo/go/syscall/route_netbsd.go
index d605ffa30f8..a10c8b65d9d 100644
--- a/libgo/go/syscall/route_netbsd.go
+++ b/libgo/go/syscall/route_netbsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -28,6 +28,8 @@ func (any *anyMessage) toRoutingMessage(b []byte) RoutingMessage {
 
 // InterfaceAnnounceMessage represents a routing message containing
 // network interface arrival and departure information.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceAnnounceMessage struct {
 	Header IfAnnounceMsghdr
 }
diff --git a/libgo/go/syscall/route_noifma_test.go b/libgo/go/syscall/route_noifma_test.go
deleted file mode 100644
index 19d5d8ebbf2..00000000000
--- a/libgo/go/syscall/route_noifma_test.go
+++ /dev/null
@@ -1,63 +0,0 @@
-// Copyright 2015 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build netbsd openbsd
-
-package syscall_test
-
-import (
-	"fmt"
-	"syscall"
-)
-
-func parseRoutingMessageHeader(m syscall.RoutingMessage) (addrFlags, error) {
-	switch m := m.(type) {
-	case *syscall.RouteMessage:
-		errno := syscall.Errno(uintptr(m.Header.Errno))
-		if errno != 0 {
-			return 0, fmt.Errorf("%T: %v, %#v", m, errno, m.Header)
-		}
-		return addrFlags(m.Header.Addrs), nil
-	case *syscall.InterfaceMessage:
-		return addrFlags(m.Header.Addrs), nil
-	case *syscall.InterfaceAddrMessage:
-		return addrFlags(m.Header.Addrs), nil
-	default:
-		panic(fmt.Sprintf("unknown routing message type: %T", m))
-	}
-}
-
-func parseRoutingSockaddrs(m syscall.RoutingMessage) ([]syscall.Sockaddr, error) {
-	switch m := m.(type) {
-	case *syscall.RouteMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	case *syscall.InterfaceMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	case *syscall.InterfaceAddrMessage:
-		sas, err := syscall.ParseRoutingSockaddr(m)
-		if err != nil {
-			return nil, fmt.Errorf("%T: %v, %#v", m, err, m.Data)
-		}
-		if err = sockaddrs(sas).match(addrFlags(m.Header.Addrs)); err != nil {
-			return nil, err
-		}
-		return sas, nil
-	default:
-		panic(fmt.Sprintf("unknown routing message type: %T", m))
-	}
-}
diff --git a/libgo/go/syscall/route_openbsd.go b/libgo/go/syscall/route_openbsd.go
index 7804a08910e..fe173adda88 100644
--- a/libgo/go/syscall/route_openbsd.go
+++ b/libgo/go/syscall/route_openbsd.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -28,6 +28,8 @@ func (any *anyMessage) toRoutingMessage(b []byte) RoutingMessage {
 
 // InterfaceAnnounceMessage represents a routing message containing
 // network interface arrival and departure information.
+//
+// Deprecated: Use golang.org/x/net/route instead.
 type InterfaceAnnounceMessage struct {
 	Header IfAnnounceMsghdr
 }
diff --git a/libgo/go/syscall/security_windows.go b/libgo/go/syscall/security_windows.go
index 1625b07ae4b..e2a9dc5f9df 100644
--- a/libgo/go/syscall/security_windows.go
+++ b/libgo/go/syscall/security_windows.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/sockcmsg_linux.go b/libgo/go/syscall/sockcmsg_linux.go
index a2e26a1f471..5a56b25bebb 100644
--- a/libgo/go/syscall/sockcmsg_linux.go
+++ b/libgo/go/syscall/sockcmsg_linux.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/syscall/sockcmsg_unix.go b/libgo/go/syscall/sockcmsg_unix.go
index bf32c987a9c..b25f8476394 100644
--- a/libgo/go/syscall/sockcmsg_unix.go
+++ b/libgo/go/syscall/sockcmsg_unix.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -70,7 +70,7 @@ func ParseSocketControlMessage(b []byte) ([]SocketControlMessage, error) {
 
 func socketControlMessageHeaderAndData(b []byte) (*Cmsghdr, []byte, error) {
 	h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
-	if h.Len < SizeofCmsghdr || int(h.Len) > len(b) {
+	if h.Len < SizeofCmsghdr || uint64(h.Len) > uint64(len(b)) {
 		return nil, nil, EINVAL
 	}
 	return h, b[cmsgAlignOf(SizeofCmsghdr):h.Len], nil
diff --git a/libgo/go/syscall/syscall.go b/libgo/go/syscall/syscall.go
index 7d42ad5dcec..bb63e227cf9 100644
--- a/libgo/go/syscall/syscall.go
+++ b/libgo/go/syscall/syscall.go
@@ -3,10 +3,10 @@
 // license that can be found in the LICENSE file.
 
 // Package syscall contains an interface to the low-level operating system
-// primitives.  The details vary depending on the underlying system, and
+// primitives. The details vary depending on the underlying system, and
 // by default, godoc will display the syscall documentation for the current
-// system.  If you want godoc to display syscall documentation for another
-// system, set $GOOS and $GOARCH to the desired system.  For example, if
+// system. If you want godoc to display syscall documentation for another
+// system, set $GOOS and $GOARCH to the desired system. For example, if
 // you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
 // to freebsd and $GOARCH to arm.
 // The primary use of syscall is inside other packages that provide a more
diff --git a/libgo/go/syscall/syscall_test.go b/libgo/go/syscall/syscall_test.go
index 846c4873d28..0a0b8b7a26d 100644
--- a/libgo/go/syscall/syscall_test.go
+++ b/libgo/go/syscall/syscall_test.go
@@ -6,6 +6,8 @@ package syscall_test
 
 import (
 	"fmt"
+	"internal/testenv"
+	"os"
 	"syscall"
 	"testing"
 )
@@ -45,3 +47,15 @@ func TestItoa(t *testing.T) {
 		t.Fatalf("itoa(%d) = %s, want %s", i, s, f)
 	}
 }
+
+// Check that permuting child process fds doesn't interfere with
+// reporting of fork/exec status. See Issue 14979.
+func TestExecErrPermutedFds(t *testing.T) {
+	testenv.MustHaveExec(t)
+
+	attr := &os.ProcAttr{Files: []*os.File{os.Stdin, os.Stderr, os.Stdout}}
+	_, err := os.StartProcess("/", []string{"/"}, attr)
+	if err == nil {
+		t.Fatalf("StartProcess of invalid program returned err = nil")
+	}
+}
diff --git a/libgo/go/syscall/syscall_unix_test.go b/libgo/go/syscall/syscall_unix_test.go
index c7b4560b76b..80544f33192 100644
--- a/libgo/go/syscall/syscall_unix_test.go
+++ b/libgo/go/syscall/syscall_unix_test.go
@@ -10,6 +10,7 @@ import (
 	"flag"
 	"fmt"
 	"internal/testenv"
+	"io"
 	"io/ioutil"
 	"net"
 	"os"
@@ -244,7 +245,7 @@ func passFDChild() {
 	}
 
 	f.Write([]byte("Hello from child process!\n"))
-	f.Seek(0, 0)
+	f.Seek(0, io.SeekStart)
 
 	rights := syscall.UnixRights(int(f.Fd()))
 	dummyByte := []byte("x")
@@ -344,7 +345,7 @@ func TestRlimit(t *testing.T) {
 }
 
 func TestSeekFailure(t *testing.T) {
-	_, err := syscall.Seek(-1, 0, 0)
+	_, err := syscall.Seek(-1, 0, io.SeekStart)
 	if err == nil {
 		t.Fatalf("Seek(-1, 0, 0) did not fail")
 	}
diff --git a/libgo/go/testing/allocs.go b/libgo/go/testing/allocs.go
index 9ec47bd4602..1eeb2d4802c 100644
--- a/libgo/go/testing/allocs.go
+++ b/libgo/go/testing/allocs.go
@@ -1,4 +1,4 @@
-// Copyright 2013 The Go Authors.  All rights reserved.
+// Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -12,7 +12,7 @@ import (
 // Although the return value has type float64, it will always be an integral value.
 //
 // To compute the number of allocations, the function will first be run once as
-// a warm-up.  The average number of allocations over the specified number of
+// a warm-up. The average number of allocations over the specified number of
 // runs will then be measured and returned.
 //
 // AllocsPerRun sets GOMAXPROCS to 1 during its measurement and will restore
diff --git a/libgo/go/testing/allocs_test.go b/libgo/go/testing/allocs_test.go
index ec17daa2b1d..5b346aaf838 100644
--- a/libgo/go/testing/allocs_test.go
+++ b/libgo/go/testing/allocs_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/testing/benchmark.go b/libgo/go/testing/benchmark.go
index 85178c2f867..5d58b85e78a 100644
--- a/libgo/go/testing/benchmark.go
+++ b/libgo/go/testing/benchmark.go
@@ -14,7 +14,7 @@ import (
 	"time"
 )
 
-var matchBenchmarks = flag.String("test.bench", "", "regular expression to select benchmarks to run")
+var matchBenchmarks = flag.String("test.bench", "", "regular expression per path component to select benchmarks to run")
 var benchTime = flag.Duration("test.benchtime", 1*time.Second, "approximate run time for each benchmark")
 var benchmarkMemory = flag.Bool("test.benchmem", false, "print memory allocations for benchmarks")
 
@@ -46,13 +46,17 @@ type InternalBenchmark struct {
 // affecting benchmark results.
 type B struct {
 	common
+	context          *benchContext
 	N                int
 	previousN        int           // number of iterations in the previous run
 	previousDuration time.Duration // total duration of the previous run
-	benchmark        InternalBenchmark
+	benchFunc        func(b *B)
+	benchTime        time.Duration
 	bytes            int64
+	missingBytes     bool // one of the subbenchmarks does not have bytes set.
 	timerOn          bool
 	showAllocResult  bool
+	hasSub           bool
 	result           BenchmarkResult
 	parallelism      int // RunParallel creates parallelism*GOMAXPROCS goroutines
 	// The initial states of memStats.Mallocs and memStats.TotalAlloc.
@@ -63,7 +67,7 @@ type B struct {
 	netBytes  uint64
 }
 
-// StartTimer starts timing a test.  This function is called automatically
+// StartTimer starts timing a test. This function is called automatically
 // before a benchmark starts, but it can also used to resume timing after
 // a call to StopTimer.
 func (b *B) StartTimer() {
@@ -76,7 +80,7 @@ func (b *B) StartTimer() {
 	}
 }
 
-// StopTimer stops timing a test.  This can be used to pause the timer
+// StopTimer stops timing a test. This can be used to pause the timer
 // while performing complex initialization that you don't
 // want to measure.
 func (b *B) StopTimer() {
@@ -132,7 +136,7 @@ func (b *B) runN(n int) {
 	b.parallelism = 1
 	b.ResetTimer()
 	b.StartTimer()
-	b.benchmark.F(b)
+	b.benchFunc(b)
 	b.StopTimer()
 	b.previousN = n
 	b.previousDuration = b.duration
@@ -185,32 +189,78 @@ func roundUp(n int) int {
 	}
 }
 
-// run times the benchmark function in a separate goroutine.
+// run1 runs the first iteration of benchFunc. It returns whether more
+// iterations of this benchmarks should be run.
+func (b *B) run1() bool {
+	if ctx := b.context; ctx != nil {
+		// Extend maxLen, if needed.
+		if n := len(b.name) + ctx.extLen + 1; n > ctx.maxLen {
+			ctx.maxLen = n + 8 // Add additional slack to avoid too many jumps in size.
+		}
+	}
+	go func() {
+		// Signal that we're done whether we return normally
+		// or by FailNow's runtime.Goexit.
+		defer func() {
+			b.signal <- true
+		}()
+
+		b.runN(1)
+	}()
+	<-b.signal
+	if b.failed {
+		fmt.Fprintf(b.w, "--- FAIL: %s\n%s", b.name, b.output)
+		return false
+	}
+	// Only print the output if we know we are not going to proceed.
+	// Otherwise it is printed in processBench.
+	if b.hasSub || b.finished {
+		tag := "BENCH"
+		if b.skipped {
+			tag = "SKIP"
+		}
+		if b.chatty && (len(b.output) > 0 || b.finished) {
+			b.trimOutput()
+			fmt.Fprintf(b.w, "--- %s: %s\n%s", tag, b.name, b.output)
+		}
+		return false
+	}
+	return true
+}
+
+// run executes the benchmark in a separate goroutine, including all of its
+// subbenchmarks. b must not have subbenchmarks.
 func (b *B) run() BenchmarkResult {
+	if b.context != nil {
+		// Running go test --test.bench
+		b.context.processBench(b) // Must call doBench.
+	} else {
+		// Running func Benchmark.
+		b.doBench()
+	}
+	return b.result
+}
+
+func (b *B) doBench() BenchmarkResult {
 	go b.launch()
 	<-b.signal
 	return b.result
 }
 
-// launch launches the benchmark function.  It gradually increases the number
+// launch launches the benchmark function. It gradually increases the number
 // of benchmark iterations until the benchmark runs for the requested benchtime.
-// It prints timing information in this form
-//		testing.BenchmarkHello	100000		19 ns/op
-// launch is run by the run function as a separate goroutine.
+// launch is run by the doBench function as a separate goroutine.
+// run1 must have been called on b.
 func (b *B) launch() {
-	// Run the benchmark for a single iteration in case it's expensive.
-	n := 1
-
 	// Signal that we're done whether we return normally
 	// or by FailNow's runtime.Goexit.
 	defer func() {
-		b.signal <- b
+		b.signal <- true
 	}()
 
-	b.runN(n)
 	// Run the benchmark for at least the specified amount of time.
-	d := *benchTime
-	for !b.failed && b.duration < d && n < 1e9 {
+	d := b.benchTime
+	for n := 1; !b.failed && b.duration < d && n < 1e9; {
 		last := n
 		// Predict required iterations.
 		if b.nsPerOp() == 0 {
@@ -299,12 +349,23 @@ func benchmarkName(name string, n int) string {
 	return name
 }
 
+type benchContext struct {
+	match *matcher
+
+	maxLen int // The largest recorded benchmark name.
+	extLen int // Maximum extension length.
+}
+
 // An internal function but exported because it is cross-package; part of the implementation
 // of the "go test" command.
 func RunBenchmarks(matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) {
+	runBenchmarksInternal(matchString, benchmarks)
+}
+
+func runBenchmarksInternal(matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) bool {
 	// If no flag was specified, don't run benchmarks.
 	if len(*matchBenchmarks) == 0 {
-		return
+		return true
 	}
 	// Collect matching benchmarks and determine longest name.
 	maxprocs := 1
@@ -313,59 +374,144 @@ func RunBenchmarks(matchString func(pat, str string) (bool, error), benchmarks [
 			maxprocs = procs
 		}
 	}
-	maxlen := 0
+	ctx := &benchContext{
+		match:  newMatcher(matchString, *matchBenchmarks, "-test.bench"),
+		extLen: len(benchmarkName("", maxprocs)),
+	}
 	var bs []InternalBenchmark
 	for _, Benchmark := range benchmarks {
-		matched, err := matchString(*matchBenchmarks, Benchmark.Name)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.bench: %s\n", err)
-			os.Exit(1)
-		}
-		if matched {
+		if _, matched := ctx.match.fullName(nil, Benchmark.Name); matched {
 			bs = append(bs, Benchmark)
 			benchName := benchmarkName(Benchmark.Name, maxprocs)
-			if l := len(benchName); l > maxlen {
-				maxlen = l
+			if l := len(benchName) + ctx.extLen + 1; l > ctx.maxLen {
+				ctx.maxLen = l
 			}
 		}
 	}
-	for _, Benchmark := range bs {
-		for _, procs := range cpuList {
-			runtime.GOMAXPROCS(procs)
-			b := &B{
+	main := &B{
+		common: common{
+			name:   "Main",
+			w:      os.Stdout,
+			chatty: *chatty,
+		},
+		benchFunc: func(b *B) {
+			for _, Benchmark := range bs {
+				b.Run(Benchmark.Name, Benchmark.F)
+			}
+		},
+		benchTime: *benchTime,
+		context:   ctx,
+	}
+	main.runN(1)
+	return !main.failed
+}
+
+// processBench runs bench b for the configured CPU counts and prints the results.
+func (ctx *benchContext) processBench(b *B) {
+	for i, procs := range cpuList {
+		runtime.GOMAXPROCS(procs)
+		benchName := benchmarkName(b.name, procs)
+		fmt.Fprintf(b.w, "%-*s\t", ctx.maxLen, benchName)
+		// Recompute the running time for all but the first iteration.
+		if i > 0 {
+			b = &B{
 				common: common{
-					signal: make(chan interface{}),
+					signal: make(chan bool),
+					name:   b.name,
+					w:      b.w,
+					chatty: b.chatty,
 				},
-				benchmark: Benchmark,
-			}
-			benchName := benchmarkName(Benchmark.Name, procs)
-			fmt.Printf("%-*s\t", maxlen, benchName)
-			r := b.run()
-			if b.failed {
-				// The output could be very long here, but probably isn't.
-				// We print it all, regardless, because we don't want to trim the reason
-				// the benchmark failed.
-				fmt.Printf("--- FAIL: %s\n%s", benchName, b.output)
-				continue
-			}
-			results := r.String()
-			if *benchmarkMemory || b.showAllocResult {
-				results += "\t" + r.MemString()
-			}
-			fmt.Println(results)
-			// Unlike with tests, we ignore the -chatty flag and always print output for
-			// benchmarks since the output generation time will skew the results.
-			if len(b.output) > 0 {
-				b.trimOutput()
-				fmt.Printf("--- BENCH: %s\n%s", benchName, b.output)
-			}
-			if p := runtime.GOMAXPROCS(-1); p != procs {
-				fmt.Fprintf(os.Stderr, "testing: %s left GOMAXPROCS set to %d\n", benchName, p)
+				benchFunc: b.benchFunc,
+				benchTime: b.benchTime,
 			}
+			b.run1()
+		}
+		r := b.doBench()
+		if b.failed {
+			// The output could be very long here, but probably isn't.
+			// We print it all, regardless, because we don't want to trim the reason
+			// the benchmark failed.
+			fmt.Fprintf(b.w, "--- FAIL: %s\n%s", benchName, b.output)
+			continue
+		}
+		results := r.String()
+		if *benchmarkMemory || b.showAllocResult {
+			results += "\t" + r.MemString()
+		}
+		fmt.Fprintln(b.w, results)
+		// Unlike with tests, we ignore the -chatty flag and always print output for
+		// benchmarks since the output generation time will skew the results.
+		if len(b.output) > 0 {
+			b.trimOutput()
+			fmt.Fprintf(b.w, "--- BENCH: %s\n%s", benchName, b.output)
+		}
+		if p := runtime.GOMAXPROCS(-1); p != procs {
+			fmt.Fprintf(os.Stderr, "testing: %s left GOMAXPROCS set to %d\n", benchName, p)
 		}
 	}
 }
 
+// Run benchmarks f as a subbenchmark with the given name. It reports
+// whether there were any failures.
+//
+// A subbenchmark is like any other benchmark. A benchmark that calls Run at
+// least once will not be measured itself and will be called once with N=1.
+func (b *B) Run(name string, f func(b *B)) bool {
+	// Since b has subbenchmarks, we will no longer run it as a benchmark itself.
+	// Release the lock and acquire it on exit to ensure locks stay paired.
+	b.hasSub = true
+	benchmarkLock.Unlock()
+	defer benchmarkLock.Lock()
+
+	benchName, ok := b.name, true
+	if b.context != nil {
+		benchName, ok = b.context.match.fullName(&b.common, name)
+	}
+	if !ok {
+		return true
+	}
+	sub := &B{
+		common: common{
+			signal: make(chan bool),
+			name:   benchName,
+			parent: &b.common,
+			level:  b.level + 1,
+			w:      b.w,
+			chatty: b.chatty,
+		},
+		benchFunc: f,
+		benchTime: b.benchTime,
+		context:   b.context,
+	}
+	if sub.run1() {
+		sub.run()
+	}
+	b.add(sub.result)
+	return !sub.failed
+}
+
+// add simulates running benchmarks in sequence in a single iteration. It is
+// used to give some meaningful results in case func Benchmark is used in
+// combination with Run.
+func (b *B) add(other BenchmarkResult) {
+	r := &b.result
+	// The aggregated BenchmarkResults resemble running all subbenchmarks as
+	// in sequence in a single benchmark.
+	r.N = 1
+	r.T += time.Duration(other.NsPerOp())
+	if other.Bytes == 0 {
+		// Summing Bytes is meaningless in aggregate if not all subbenchmarks
+		// set it.
+		b.missingBytes = true
+		r.Bytes = 0
+	}
+	if !b.missingBytes {
+		r.Bytes += other.Bytes
+	}
+	r.MemAllocs += uint64(other.AllocsPerOp())
+	r.MemBytes += uint64(other.AllocedBytesPerOp())
+}
+
 // trimOutput shortens the output from a benchmark, which can be very long.
 func (b *B) trimOutput() {
 	// The output is likely to appear multiple times because the benchmark
@@ -416,8 +562,11 @@ func (pb *PB) Next() bool {
 // The body function will be run in each goroutine. It should set up any
 // goroutine-local state and then iterate until pb.Next returns false.
 // It should not use the StartTimer, StopTimer, or ResetTimer functions,
-// because they have global effect.
+// because they have global effect. It should also not call Run.
 func (b *B) RunParallel(body func(*PB)) {
+	if b.N == 0 {
+		return // Nothing to do when probing.
+	}
 	// Calculate grain size as number of iterations that take ~100µs.
 	// 100µs is enough to amortize the overhead and provide sufficient
 	// dynamic load balancing.
@@ -466,12 +615,24 @@ func (b *B) SetParallelism(p int) {
 
 // Benchmark benchmarks a single function. Useful for creating
 // custom benchmarks that do not use the "go test" command.
+//
+// If f calls Run, the result will be an estimate of running all its
+// subbenchmarks that don't call Run in sequence in a single benchmark.
 func Benchmark(f func(b *B)) BenchmarkResult {
 	b := &B{
 		common: common{
-			signal: make(chan interface{}),
+			signal: make(chan bool),
+			w:      discard{},
 		},
-		benchmark: InternalBenchmark{"", f},
+		benchFunc: f,
+		benchTime: *benchTime,
+	}
+	if !b.run1() {
+		return BenchmarkResult{}
 	}
 	return b.run()
 }
+
+type discard struct{}
+
+func (discard) Write(b []byte) (n int, err error) { return len(b), nil }
diff --git a/libgo/go/testing/example.go b/libgo/go/testing/example.go
index 30baf27030a..fd8343f3bfc 100644
--- a/libgo/go/testing/example.go
+++ b/libgo/go/testing/example.go
@@ -9,14 +9,16 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"sort"
 	"strings"
 	"time"
 )
 
 type InternalExample struct {
-	Name   string
-	F      func()
-	Output string
+	Name      string
+	F         func()
+	Output    string
+	Unordered bool
 }
 
 func RunExamples(matchString func(pat, str string) (bool, error), examples []InternalExample) (ok bool) {
@@ -41,6 +43,12 @@ func RunExamples(matchString func(pat, str string) (bool, error), examples []Int
 	return
 }
 
+func sortLines(output string) string {
+	lines := strings.Split(output, "\n")
+	sort.Strings(lines)
+	return strings.Join(lines, "\n")
+}
+
 func runExample(eg InternalExample) (ok bool) {
 	if *chatty {
 		fmt.Printf("=== RUN   %s\n", eg.Name)
@@ -80,8 +88,16 @@ func runExample(eg InternalExample) (ok bool) {
 
 		var fail string
 		err := recover()
-		if g, e := strings.TrimSpace(out), strings.TrimSpace(eg.Output); g != e && err == nil {
-			fail = fmt.Sprintf("got:\n%s\nwant:\n%s\n", g, e)
+		got := strings.TrimSpace(out)
+		want := strings.TrimSpace(eg.Output)
+		if eg.Unordered {
+			if sortLines(got) != sortLines(want) && err == nil {
+				fail = fmt.Sprintf("got:\n%s\nwant (unordered):\n%s\n", out, eg.Output)
+			}
+		} else {
+			if got != want && err == nil {
+				fail = fmt.Sprintf("got:\n%s\nwant:\n%s\n", got, want)
+			}
 		}
 		if fail != "" || err != nil {
 			fmt.Printf("--- FAIL: %s (%s)\n%s", eg.Name, dstr, fail)
diff --git a/libgo/go/testing/iotest/reader.go b/libgo/go/testing/iotest/reader.go
index a5bccca9063..8d82018fd6c 100644
--- a/libgo/go/testing/iotest/reader.go
+++ b/libgo/go/testing/iotest/reader.go
@@ -71,7 +71,7 @@ func (r *dataErrReader) Read(p []byte) (n int, err error) {
 var ErrTimeout = errors.New("timeout")
 
 // TimeoutReader returns ErrTimeout on the second read
-// with no data.  Subsequent calls to read succeed.
+// with no data. Subsequent calls to read succeed.
 func TimeoutReader(r io.Reader) io.Reader { return &timeoutReader{r, 0} }
 
 type timeoutReader struct {
diff --git a/libgo/go/testing/match.go b/libgo/go/testing/match.go
new file mode 100644
index 00000000000..77510357602
--- /dev/null
+++ b/libgo/go/testing/match.go
@@ -0,0 +1,167 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testing
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+// matcher sanitizes, uniques, and filters names of subtests and subbenchmarks.
+type matcher struct {
+	filter    []string
+	matchFunc func(pat, str string) (bool, error)
+
+	mu       sync.Mutex
+	subNames map[string]int64
+}
+
+// TODO: fix test_main to avoid race and improve caching, also allowing to
+// eliminate this Mutex.
+var matchMutex sync.Mutex
+
+func newMatcher(matchString func(pat, str string) (bool, error), patterns, name string) *matcher {
+	var filter []string
+	if patterns != "" {
+		filter = splitRegexp(patterns)
+		for i, s := range filter {
+			filter[i] = rewrite(s)
+		}
+		// Verify filters before doing any processing.
+		for i, s := range filter {
+			if _, err := matchString(s, "non-empty"); err != nil {
+				fmt.Fprintf(os.Stderr, "testing: invalid regexp for element %d of %s (%q): %s\n", i, name, s, err)
+				os.Exit(1)
+			}
+		}
+	}
+	return &matcher{
+		filter:    filter,
+		matchFunc: matchString,
+		subNames:  map[string]int64{},
+	}
+}
+
+func (m *matcher) fullName(c *common, subname string) (name string, ok bool) {
+	name = subname
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	if c != nil && c.level > 0 {
+		name = m.unique(c.name, rewrite(subname))
+	}
+
+	matchMutex.Lock()
+	defer matchMutex.Unlock()
+
+	// We check the full array of paths each time to allow for the case that
+	// a pattern contains a '/'.
+	for i, s := range strings.Split(name, "/") {
+		if i >= len(m.filter) {
+			break
+		}
+		if ok, _ := m.matchFunc(m.filter[i], s); !ok {
+			return name, false
+		}
+	}
+	return name, true
+}
+
+func splitRegexp(s string) []string {
+	a := make([]string, 0, strings.Count(s, "/"))
+	cs := 0
+	cp := 0
+	for i := 0; i < len(s); {
+		switch s[i] {
+		case '[':
+			cs++
+		case ']':
+			if cs--; cs < 0 { // An unmatched ']' is legal.
+				cs = 0
+			}
+		case '(':
+			if cs == 0 {
+				cp++
+			}
+		case ')':
+			if cs == 0 {
+				cp--
+			}
+		case '\\':
+			i++
+		case '/':
+			if cs == 0 && cp == 0 {
+				a = append(a, s[:i])
+				s = s[i+1:]
+				i = 0
+				continue
+			}
+		}
+		i++
+	}
+	return append(a, s)
+}
+
+// unique creates a unique name for the given parent and subname by affixing it
+// with one ore more counts, if necessary.
+func (m *matcher) unique(parent, subname string) string {
+	name := fmt.Sprintf("%s/%s", parent, subname)
+	empty := subname == ""
+	for {
+		next, exists := m.subNames[name]
+		if !empty && !exists {
+			m.subNames[name] = 1 // next count is 1
+			return name
+		}
+		// Name was already used. We increment with the count and append a
+		// string with the count.
+		m.subNames[name] = next + 1
+
+		// Add a count to guarantee uniqueness.
+		name = fmt.Sprintf("%s#%02d", name, next)
+		empty = false
+	}
+}
+
+// rewrite rewrites a subname to having only printable characters and no white
+// space.
+func rewrite(s string) string {
+	b := []byte{}
+	for _, r := range s {
+		switch {
+		case isSpace(r):
+			b = append(b, '_')
+		case !strconv.IsPrint(r):
+			s := strconv.QuoteRune(r)
+			b = append(b, s[1:len(s)-1]...)
+		default:
+			b = append(b, string(r)...)
+		}
+	}
+	return string(b)
+}
+
+func isSpace(r rune) bool {
+	if r < 0x2000 {
+		switch r {
+		// Note: not the same as Unicode Z class.
+		case '\t', '\n', '\v', '\f', '\r', ' ', 0x85, 0xA0, 0x1680:
+			return true
+		}
+	} else {
+		if r <= 0x200a {
+			return true
+		}
+		switch r {
+		case 0x2028, 0x2029, 0x202f, 0x205f, 0x3000:
+			return true
+		}
+	}
+	return false
+}
diff --git a/libgo/go/testing/match_test.go b/libgo/go/testing/match_test.go
new file mode 100644
index 00000000000..8c1c5f4452c
--- /dev/null
+++ b/libgo/go/testing/match_test.go
@@ -0,0 +1,185 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testing
+
+import (
+	"reflect"
+	"regexp"
+	"unicode"
+)
+
+// Verify that our IsSpace agrees with unicode.IsSpace.
+func TestIsSpace(t *T) {
+	n := 0
+	for r := rune(0); r <= unicode.MaxRune; r++ {
+		if isSpace(r) != unicode.IsSpace(r) {
+			t.Errorf("IsSpace(%U)=%t incorrect", r, isSpace(r))
+			n++
+			if n > 10 {
+				return
+			}
+		}
+	}
+}
+
+func TestSplitRegexp(t *T) {
+	res := func(s ...string) []string { return s }
+	testCases := []struct {
+		pattern string
+		result  []string
+	}{
+		// Correct patterns
+		// If a regexp pattern is correct, all split regexps need to be correct
+		// as well.
+		{"", res("")},
+		{"/", res("", "")},
+		{"//", res("", "", "")},
+		{"A", res("A")},
+		{"A/B", res("A", "B")},
+		{"A/B/", res("A", "B", "")},
+		{"/A/B/", res("", "A", "B", "")},
+		{"[A]/(B)", res("[A]", "(B)")},
+		{"[/]/[/]", res("[/]", "[/]")},
+		{"[/]/[:/]", res("[/]", "[:/]")},
+		{"/]", res("", "]")},
+		{"]/", res("]", "")},
+		{"]/[/]", res("]", "[/]")},
+		{`([)/][(])`, res(`([)/][(])`)},
+		{"[(]/[)]", res("[(]", "[)]")},
+
+		// Faulty patterns
+		// Errors in original should produce at least one faulty regexp in results.
+		{")/", res(")/")},
+		{")/(/)", res(")/(", ")")},
+		{"a[/)b", res("a[/)b")},
+		{"(/]", res("(/]")},
+		{"(/", res("(/")},
+		{"[/]/[/", res("[/]", "[/")},
+		{`\p{/}`, res(`\p{`, "}")},
+		{`\p/`, res(`\p`, "")},
+		{`[[:/:]]`, res(`[[:/:]]`)},
+	}
+	for _, tc := range testCases {
+		a := splitRegexp(tc.pattern)
+		if !reflect.DeepEqual(a, tc.result) {
+			t.Errorf("splitRegexp(%q) = %#v; want %#v", tc.pattern, a, tc.result)
+		}
+
+		// If there is any error in the pattern, one of the returned subpatterns
+		// needs to have an error as well.
+		if _, err := regexp.Compile(tc.pattern); err != nil {
+			ok := true
+			for _, re := range a {
+				if _, err := regexp.Compile(re); err != nil {
+					ok = false
+				}
+			}
+			if ok {
+				t.Errorf("%s: expected error in any of %q", tc.pattern, a)
+			}
+		}
+	}
+}
+
+func TestMatcher(t *T) {
+	testCases := []struct {
+		pattern     string
+		parent, sub string
+		ok          bool
+	}{
+		// Behavior without subtests.
+		{"", "", "TestFoo", true},
+		{"TestFoo", "", "TestFoo", true},
+		{"TestFoo/", "", "TestFoo", true},
+		{"TestFoo/bar/baz", "", "TestFoo", true},
+		{"TestFoo", "", "TestBar", false},
+		{"TestFoo/", "", "TestBar", false},
+		{"TestFoo/bar/baz", "", "TestBar/bar/baz", false},
+
+		// with subtests
+		{"", "TestFoo", "x", true},
+		{"TestFoo", "TestFoo", "x", true},
+		{"TestFoo/", "TestFoo", "x", true},
+		{"TestFoo/bar/baz", "TestFoo", "bar", true},
+		// Subtest with a '/' in its name still allows for copy and pasted names
+		// to match.
+		{"TestFoo/bar/baz", "TestFoo", "bar/baz", true},
+		{"TestFoo/bar/baz", "TestFoo/bar", "baz", true},
+		{"TestFoo/bar/baz", "TestFoo", "x", false},
+		{"TestFoo", "TestBar", "x", false},
+		{"TestFoo/", "TestBar", "x", false},
+		{"TestFoo/bar/baz", "TestBar", "x/bar/baz", false},
+
+		// subtests only
+		{"", "TestFoo", "x", true},
+		{"/", "TestFoo", "x", true},
+		{"./", "TestFoo", "x", true},
+		{"./.", "TestFoo", "x", true},
+		{"/bar/baz", "TestFoo", "bar", true},
+		{"/bar/baz", "TestFoo", "bar/baz", true},
+		{"//baz", "TestFoo", "bar/baz", true},
+		{"//", "TestFoo", "bar/baz", true},
+		{"/bar/baz", "TestFoo/bar", "baz", true},
+		{"//foo", "TestFoo", "bar/baz", false},
+		{"/bar/baz", "TestFoo", "x", false},
+		{"/bar/baz", "TestBar", "x/bar/baz", false},
+	}
+
+	for _, tc := range testCases {
+		m := newMatcher(regexp.MatchString, tc.pattern, "-test.run")
+
+		parent := &common{name: tc.parent}
+		if tc.parent != "" {
+			parent.level = 1
+		}
+		if n, ok := m.fullName(parent, tc.sub); ok != tc.ok {
+			t.Errorf("for pattern %q, fullName(parent=%q, sub=%q) = %q, ok %v; want ok %v",
+				tc.pattern, tc.parent, tc.sub, n, ok, tc.ok)
+		}
+	}
+}
+
+func TestNaming(t *T) {
+	m := newMatcher(regexp.MatchString, "", "")
+
+	parent := &common{name: "x", level: 1} // top-level test.
+
+	// Rig the matcher with some preloaded values.
+	m.subNames["x/b"] = 1000
+
+	testCases := []struct {
+		name, want string
+	}{
+		// Uniqueness
+		{"", "x/#00"},
+		{"", "x/#01"},
+
+		{"t", "x/t"},
+		{"t", "x/t#01"},
+		{"t", "x/t#02"},
+
+		{"a#01", "x/a#01"}, // user has subtest with this name.
+		{"a", "x/a"},       // doesn't conflict with this name.
+		{"a", "x/a#01#01"}, // conflict, add disambiguating string.
+		{"a", "x/a#02"},    // This string is claimed now, so resume
+		{"a", "x/a#03"},    // with counting.
+		{"a#02", "x/a#02#01"},
+
+		{"b", "x/b#1000"}, // rigged, see above
+		{"b", "x/b#1001"},
+
+		// // Sanitizing
+		{"A:1 B:2", "x/A:1_B:2"},
+		{"s\t\r\u00a0", "x/s___"},
+		{"\x01", `x/\x01`},
+		{"\U0010ffff", `x/\U0010ffff`},
+	}
+
+	for i, tc := range testCases {
+		if got, _ := m.fullName(parent, tc.name); got != tc.want {
+			t.Errorf("%d:%s: got %q; want %q", i, tc.name, got, tc.want)
+		}
+	}
+}
diff --git a/libgo/go/testing/quick/quick.go b/libgo/go/testing/quick/quick.go
index 187195c7590..798d41aa7d1 100644
--- a/libgo/go/testing/quick/quick.go
+++ b/libgo/go/testing/quick/quick.go
@@ -239,8 +239,8 @@ func (s *CheckEqualError) Error() string {
 }
 
 // Check looks for an input to f, any function that returns bool,
-// such that f returns false.  It calls f repeatedly, with arbitrary
-// values for each argument.  If f returns false on a given input,
+// such that f returns false. It calls f repeatedly, with arbitrary
+// values for each argument. If f returns false on a given input,
 // Check returns that input as a *CheckError.
 // For example:
 //
@@ -253,24 +253,21 @@ func (s *CheckEqualError) Error() string {
 // 			t.Error(err)
 // 		}
 // 	}
-func Check(f interface{}, config *Config) (err error) {
+func Check(f interface{}, config *Config) error {
 	if config == nil {
 		config = &defaultConfig
 	}
 
 	fVal, fType, ok := functionAndType(f)
 	if !ok {
-		err = SetupError("argument is not a function")
-		return
+		return SetupError("argument is not a function")
 	}
 
 	if fType.NumOut() != 1 {
-		err = SetupError("function does not return one value")
-		return
+		return SetupError("function does not return one value")
 	}
 	if fType.Out(0).Kind() != reflect.Bool {
-		err = SetupError("function does not return a bool")
-		return
+		return SetupError("function does not return a bool")
 	}
 
 	arguments := make([]reflect.Value, fType.NumIn())
@@ -278,43 +275,39 @@ func Check(f interface{}, config *Config) (err error) {
 	maxCount := config.getMaxCount()
 
 	for i := 0; i < maxCount; i++ {
-		err = arbitraryValues(arguments, fType, config, rand)
+		err := arbitraryValues(arguments, fType, config, rand)
 		if err != nil {
-			return
+			return err
 		}
 
 		if !fVal.Call(arguments)[0].Bool() {
-			err = &CheckError{i + 1, toInterfaces(arguments)}
-			return
+			return &CheckError{i + 1, toInterfaces(arguments)}
 		}
 	}
 
-	return
+	return nil
 }
 
 // CheckEqual looks for an input on which f and g return different results.
 // It calls f and g repeatedly with arbitrary values for each argument.
 // If f and g return different answers, CheckEqual returns a *CheckEqualError
 // describing the input and the outputs.
-func CheckEqual(f, g interface{}, config *Config) (err error) {
+func CheckEqual(f, g interface{}, config *Config) error {
 	if config == nil {
 		config = &defaultConfig
 	}
 
 	x, xType, ok := functionAndType(f)
 	if !ok {
-		err = SetupError("f is not a function")
-		return
+		return SetupError("f is not a function")
 	}
 	y, yType, ok := functionAndType(g)
 	if !ok {
-		err = SetupError("g is not a function")
-		return
+		return SetupError("g is not a function")
 	}
 
 	if xType != yType {
-		err = SetupError("functions have different types")
-		return
+		return SetupError("functions have different types")
 	}
 
 	arguments := make([]reflect.Value, xType.NumIn())
@@ -322,21 +315,20 @@ func CheckEqual(f, g interface{}, config *Config) (err error) {
 	maxCount := config.getMaxCount()
 
 	for i := 0; i < maxCount; i++ {
-		err = arbitraryValues(arguments, xType, config, rand)
+		err := arbitraryValues(arguments, xType, config, rand)
 		if err != nil {
-			return
+			return err
 		}
 
 		xOut := toInterfaces(x.Call(arguments))
 		yOut := toInterfaces(y.Call(arguments))
 
 		if !reflect.DeepEqual(xOut, yOut) {
-			err = &CheckEqualError{CheckError{i + 1, toInterfaces(arguments)}, xOut, yOut}
-			return
+			return &CheckEqualError{CheckError{i + 1, toInterfaces(arguments)}, xOut, yOut}
 		}
 	}
 
-	return
+	return nil
 }
 
 // arbitraryValues writes Values to args such that args contains Values
diff --git a/libgo/go/testing/sub_test.go b/libgo/go/testing/sub_test.go
new file mode 100644
index 00000000000..2a24aaacfd7
--- /dev/null
+++ b/libgo/go/testing/sub_test.go
@@ -0,0 +1,517 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testing
+
+import (
+	"bytes"
+	"regexp"
+	"strings"
+	"sync/atomic"
+	"time"
+)
+
+func TestTestContext(t *T) {
+	const (
+		add1 = 0
+		done = 1
+	)
+	// After each of the calls are applied to the context, the
+	type call struct {
+		typ int // run or done
+		// result from applying the call
+		running int
+		waiting int
+		started bool
+	}
+	testCases := []struct {
+		max int
+		run []call
+	}{{
+		max: 1,
+		run: []call{
+			{typ: add1, running: 1, waiting: 0, started: true},
+			{typ: done, running: 0, waiting: 0, started: false},
+		},
+	}, {
+		max: 1,
+		run: []call{
+			{typ: add1, running: 1, waiting: 0, started: true},
+			{typ: add1, running: 1, waiting: 1, started: false},
+			{typ: done, running: 1, waiting: 0, started: true},
+			{typ: done, running: 0, waiting: 0, started: false},
+			{typ: add1, running: 1, waiting: 0, started: true},
+		},
+	}, {
+		max: 3,
+		run: []call{
+			{typ: add1, running: 1, waiting: 0, started: true},
+			{typ: add1, running: 2, waiting: 0, started: true},
+			{typ: add1, running: 3, waiting: 0, started: true},
+			{typ: add1, running: 3, waiting: 1, started: false},
+			{typ: add1, running: 3, waiting: 2, started: false},
+			{typ: add1, running: 3, waiting: 3, started: false},
+			{typ: done, running: 3, waiting: 2, started: true},
+			{typ: add1, running: 3, waiting: 3, started: false},
+			{typ: done, running: 3, waiting: 2, started: true},
+			{typ: done, running: 3, waiting: 1, started: true},
+			{typ: done, running: 3, waiting: 0, started: true},
+			{typ: done, running: 2, waiting: 0, started: false},
+			{typ: done, running: 1, waiting: 0, started: false},
+			{typ: done, running: 0, waiting: 0, started: false},
+		},
+	}}
+	for i, tc := range testCases {
+		ctx := &testContext{
+			startParallel: make(chan bool),
+			maxParallel:   tc.max,
+		}
+		for j, call := range tc.run {
+			doCall := func(f func()) chan bool {
+				done := make(chan bool)
+				go func() {
+					f()
+					done <- true
+				}()
+				return done
+			}
+			started := false
+			switch call.typ {
+			case add1:
+				signal := doCall(ctx.waitParallel)
+				select {
+				case <-signal:
+					started = true
+				case ctx.startParallel <- true:
+					<-signal
+				}
+			case done:
+				signal := doCall(ctx.release)
+				select {
+				case <-signal:
+				case <-ctx.startParallel:
+					started = true
+					<-signal
+				}
+			}
+			if started != call.started {
+				t.Errorf("%d:%d:started: got %v; want %v", i, j, started, call.started)
+			}
+			if ctx.running != call.running {
+				t.Errorf("%d:%d:running: got %v; want %v", i, j, ctx.running, call.running)
+			}
+			if ctx.numWaiting != call.waiting {
+				t.Errorf("%d:%d:waiting: got %v; want %v", i, j, ctx.numWaiting, call.waiting)
+			}
+		}
+	}
+}
+
+func TestTRun(t *T) {
+	realTest := t
+	testCases := []struct {
+		desc   string
+		ok     bool
+		maxPar int
+		chatty bool
+		output string
+		f      func(*T)
+	}{{
+		desc:   "failnow skips future sequential and parallel tests at same level",
+		ok:     false,
+		maxPar: 1,
+		output: `
+--- FAIL: failnow skips future sequential and parallel tests at same level (N.NNs)
+    --- FAIL: failnow skips future sequential and parallel tests at same level/#00 (N.NNs)
+    `,
+		f: func(t *T) {
+			ranSeq := false
+			ranPar := false
+			t.Run("", func(t *T) {
+				t.Run("par", func(t *T) {
+					t.Parallel()
+					ranPar = true
+				})
+				t.Run("seq", func(t *T) {
+					ranSeq = true
+				})
+				t.FailNow()
+				t.Run("seq", func(t *T) {
+					realTest.Error("test must be skipped")
+				})
+				t.Run("par", func(t *T) {
+					t.Parallel()
+					realTest.Error("test must be skipped.")
+				})
+			})
+			if !ranPar {
+				realTest.Error("parallel test was not run")
+			}
+			if !ranSeq {
+				realTest.Error("sequential test was not run")
+			}
+		},
+	}, {
+		desc:   "failure in parallel test propagates upwards",
+		ok:     false,
+		maxPar: 1,
+		output: `
+--- FAIL: failure in parallel test propagates upwards (N.NNs)
+    --- FAIL: failure in parallel test propagates upwards/#00 (N.NNs)
+        --- FAIL: failure in parallel test propagates upwards/#00/par (N.NNs)
+		`,
+		f: func(t *T) {
+			t.Run("", func(t *T) {
+				t.Parallel()
+				t.Run("par", func(t *T) {
+					t.Parallel()
+					t.Fail()
+				})
+			})
+		},
+	}, {
+		desc:   "skipping without message, chatty",
+		ok:     true,
+		chatty: true,
+		output: `
+=== RUN   skipping without message, chatty
+--- SKIP: skipping without message, chatty (N.NNs)`,
+		f: func(t *T) { t.SkipNow() },
+	}, {
+		desc:   "chatty with recursion",
+		ok:     true,
+		chatty: true,
+		output: `
+=== RUN   chatty with recursion
+=== RUN   chatty with recursion/#00
+=== RUN   chatty with recursion/#00/#00
+--- PASS: chatty with recursion (N.NNs)
+    --- PASS: chatty with recursion/#00 (N.NNs)
+        --- PASS: chatty with recursion/#00/#00 (N.NNs)`,
+		f: func(t *T) {
+			t.Run("", func(t *T) {
+				t.Run("", func(t *T) {})
+			})
+		},
+	}, {
+		desc: "skipping without message, not chatty",
+		ok:   true,
+		f:    func(t *T) { t.SkipNow() },
+	}, {
+		desc: "skipping after error",
+		output: `
+--- FAIL: skipping after error (N.NNs)
+	sub_test.go:NNN: an error
+	sub_test.go:NNN: skipped`,
+		f: func(t *T) {
+			t.Error("an error")
+			t.Skip("skipped")
+		},
+	}, {
+		desc:   "use Run to locally synchronize parallelism",
+		ok:     true,
+		maxPar: 1,
+		f: func(t *T) {
+			var count uint32
+			t.Run("waitGroup", func(t *T) {
+				for i := 0; i < 4; i++ {
+					t.Run("par", func(t *T) {
+						t.Parallel()
+						atomic.AddUint32(&count, 1)
+					})
+				}
+			})
+			if count != 4 {
+				t.Errorf("count was %d; want 4", count)
+			}
+		},
+	}, {
+		desc: "alternate sequential and parallel",
+		// Sequential tests should partake in the counting of running threads.
+		// Otherwise, if one runs parallel subtests in sequential tests that are
+		// itself subtests of parallel tests, the counts can get askew.
+		ok:     true,
+		maxPar: 1,
+		f: func(t *T) {
+			t.Run("a", func(t *T) {
+				t.Parallel()
+				t.Run("b", func(t *T) {
+					// Sequential: ensure running count is decremented.
+					t.Run("c", func(t *T) {
+						t.Parallel()
+					})
+
+				})
+			})
+		},
+	}, {
+		desc: "alternate sequential and parallel 2",
+		// Sequential tests should partake in the counting of running threads.
+		// Otherwise, if one runs parallel subtests in sequential tests that are
+		// itself subtests of parallel tests, the counts can get askew.
+		ok:     true,
+		maxPar: 2,
+		f: func(t *T) {
+			for i := 0; i < 2; i++ {
+				t.Run("a", func(t *T) {
+					t.Parallel()
+					time.Sleep(time.Nanosecond)
+					for i := 0; i < 2; i++ {
+						t.Run("b", func(t *T) {
+							time.Sleep(time.Nanosecond)
+							for i := 0; i < 2; i++ {
+								t.Run("c", func(t *T) {
+									t.Parallel()
+									time.Sleep(time.Nanosecond)
+								})
+							}
+
+						})
+					}
+				})
+			}
+		},
+	}, {
+		desc:   "stress test",
+		ok:     true,
+		maxPar: 4,
+		f: func(t *T) {
+			t.Parallel()
+			for i := 0; i < 12; i++ {
+				t.Run("a", func(t *T) {
+					t.Parallel()
+					time.Sleep(time.Nanosecond)
+					for i := 0; i < 12; i++ {
+						t.Run("b", func(t *T) {
+							time.Sleep(time.Nanosecond)
+							for i := 0; i < 12; i++ {
+								t.Run("c", func(t *T) {
+									t.Parallel()
+									time.Sleep(time.Nanosecond)
+									t.Run("d1", func(t *T) {})
+									t.Run("d2", func(t *T) {})
+									t.Run("d3", func(t *T) {})
+									t.Run("d4", func(t *T) {})
+								})
+							}
+						})
+					}
+				})
+			}
+		},
+	}, {
+		desc:   "skip output",
+		ok:     true,
+		maxPar: 4,
+		f: func(t *T) {
+			t.Skip()
+		},
+	}, {
+		desc:   "panic on goroutine fail after test exit",
+		ok:     false,
+		maxPar: 4,
+		f: func(t *T) {
+			ch := make(chan bool)
+			t.Run("", func(t *T) {
+				go func() {
+					<-ch
+					defer func() {
+						if r := recover(); r == nil {
+							realTest.Errorf("expected panic")
+						}
+						ch <- true
+					}()
+					t.Errorf("failed after success")
+				}()
+			})
+			ch <- true
+			<-ch
+		},
+	}}
+	for _, tc := range testCases {
+		ctx := newTestContext(tc.maxPar, newMatcher(regexp.MatchString, "", ""))
+		buf := &bytes.Buffer{}
+		root := &T{
+			common: common{
+				signal: make(chan bool),
+				name:   "Test",
+				w:      buf,
+				chatty: tc.chatty,
+			},
+			context: ctx,
+		}
+		ok := root.Run(tc.desc, tc.f)
+		ctx.release()
+
+		if ok != tc.ok {
+			t.Errorf("%s:ok: got %v; want %v", tc.desc, ok, tc.ok)
+		}
+		if ok != !root.Failed() {
+			t.Errorf("%s:root failed: got %v; want %v", tc.desc, !ok, root.Failed())
+		}
+		if ctx.running != 0 || ctx.numWaiting != 0 {
+			t.Errorf("%s:running and waiting non-zero: got %d and %d", tc.desc, ctx.running, ctx.numWaiting)
+		}
+		got := strings.TrimSpace(buf.String())
+		want := strings.TrimSpace(tc.output)
+		re := makeRegexp(want)
+		if ok, err := regexp.MatchString(re, got); !ok || err != nil {
+			t.Errorf("%s:ouput:\ngot:\n%s\nwant:\n%s", tc.desc, got, want)
+		}
+	}
+}
+
+func TestBRun(t *T) {
+	work := func(b *B) {
+		for i := 0; i < b.N; i++ {
+			time.Sleep(time.Nanosecond)
+		}
+	}
+	testCases := []struct {
+		desc   string
+		failed bool
+		chatty bool
+		output string
+		f      func(*B)
+	}{{
+		desc: "simulate sequential run of subbenchmarks.",
+		f: func(b *B) {
+			b.Run("", func(b *B) { work(b) })
+			time1 := b.result.NsPerOp()
+			b.Run("", func(b *B) { work(b) })
+			time2 := b.result.NsPerOp()
+			if time1 >= time2 {
+				t.Errorf("no time spent in benchmark t1 >= t2 (%d >= %d)", time1, time2)
+			}
+		},
+	}, {
+		desc: "bytes set by all benchmarks",
+		f: func(b *B) {
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			if b.result.Bytes != 20 {
+				t.Errorf("bytes: got: %d; want 20", b.result.Bytes)
+			}
+		},
+	}, {
+		desc: "bytes set by some benchmarks",
+		// In this case the bytes result is meaningless, so it must be 0.
+		f: func(b *B) {
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			b.Run("", func(b *B) { work(b) })
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			if b.result.Bytes != 0 {
+				t.Errorf("bytes: got: %d; want 0", b.result.Bytes)
+			}
+		},
+	}, {
+		desc:   "failure carried over to root",
+		failed: true,
+		output: "--- FAIL: root",
+		f:      func(b *B) { b.Fail() },
+	}, {
+		desc:   "skipping without message, chatty",
+		chatty: true,
+		output: "--- SKIP: root",
+		f:      func(b *B) { b.SkipNow() },
+	}, {
+		desc:   "skipping with message, chatty",
+		chatty: true,
+		output: `
+--- SKIP: root
+	sub_test.go:NNN: skipping`,
+		f: func(b *B) { b.Skip("skipping") },
+	}, {
+		desc:   "chatty with recursion",
+		chatty: true,
+		f: func(b *B) {
+			b.Run("", func(b *B) {
+				b.Run("", func(b *B) {})
+			})
+		},
+	}, {
+		desc: "skipping without message, not chatty",
+		f:    func(b *B) { b.SkipNow() },
+	}, {
+		desc:   "skipping after error",
+		failed: true,
+		output: `
+--- FAIL: root
+	sub_test.go:NNN: an error
+	sub_test.go:NNN: skipped`,
+		f: func(b *B) {
+			b.Error("an error")
+			b.Skip("skipped")
+		},
+	}, {
+		desc: "memory allocation",
+		f: func(b *B) {
+			const bufSize = 256
+			alloc := func(b *B) {
+				var buf [bufSize]byte
+				for i := 0; i < b.N; i++ {
+					_ = append([]byte(nil), buf[:]...)
+				}
+			}
+			b.Run("", func(b *B) { alloc(b) })
+			b.Run("", func(b *B) { alloc(b) })
+			// runtime.MemStats sometimes reports more allocations than the
+			// benchmark is responsible for. Luckily the point of this test is
+			// to ensure that the results are not underreported, so we can
+			// simply verify the lower bound.
+			if got := b.result.MemAllocs; got < 2 {
+				t.Errorf("MemAllocs was %v; want 2", got)
+			}
+			if got := b.result.MemBytes; got < 2*bufSize {
+				t.Errorf("MemBytes was %v; want %v", got, 2*bufSize)
+			}
+		},
+	}}
+	for _, tc := range testCases {
+		var ok bool
+		buf := &bytes.Buffer{}
+		// This is almost like the Benchmark function, except that we override
+		// the benchtime and catch the failure result of the subbenchmark.
+		root := &B{
+			common: common{
+				signal: make(chan bool),
+				name:   "root",
+				w:      buf,
+				chatty: tc.chatty,
+			},
+			benchFunc: func(b *B) { ok = b.Run("test", tc.f) }, // Use Run to catch failure.
+			benchTime: time.Microsecond,
+		}
+		root.runN(1)
+		if ok != !tc.failed {
+			t.Errorf("%s:ok: got %v; want %v", tc.desc, ok, !tc.failed)
+		}
+		if !ok != root.Failed() {
+			t.Errorf("%s:root failed: got %v; want %v", tc.desc, !ok, root.Failed())
+		}
+		// All tests are run as subtests
+		if root.result.N != 1 {
+			t.Errorf("%s: N for parent benchmark was %d; want 1", tc.desc, root.result.N)
+		}
+		got := strings.TrimSpace(buf.String())
+		want := strings.TrimSpace(tc.output)
+		re := makeRegexp(want)
+		if ok, err := regexp.MatchString(re, got); !ok || err != nil {
+			t.Errorf("%s:ouput:\ngot:\n%s\nwant:\n%s", tc.desc, got, want)
+		}
+	}
+}
+
+func makeRegexp(s string) string {
+	s = strings.Replace(s, ":NNN:", `:\d\d\d:`, -1)
+	s = strings.Replace(s, "(N.NNs)", `\(\d*\.\d*s\)`, -1)
+	return s
+}
+
+func TestBenchmarkOutput(t *T) {
+	// Ensure Benchmark initialized common.w by invoking it with an error and
+	// normal case.
+	Benchmark(func(b *B) { b.Error("do not print this output") })
+	Benchmark(func(b *B) {})
+}
diff --git a/libgo/go/testing/testing.go b/libgo/go/testing/testing.go
index bcbe8f15c55..5a3a9aba218 100644
--- a/libgo/go/testing/testing.go
+++ b/libgo/go/testing/testing.go
@@ -45,7 +45,7 @@
 //
 // The benchmark function must run the target code b.N times.
 // During benchmark execution, b.N is adjusted until the benchmark function lasts
-// long enough to be timed reliably.  The output
+// long enough to be timed reliably. The output
 //     BenchmarkHello    10000000    282 ns/op
 // means that the loop ran 10000000 times at a speed of 282 ns per loop.
 //
@@ -118,6 +118,61 @@
 // example function, at least one other function, type, variable, or constant
 // declaration, and no test or benchmark functions.
 //
+// Subtests and Sub-benchmarks
+//
+// The Run methods of T and B allow defining subtests and sub-benchmarks,
+// without having to define separate functions for each. This enables uses
+// like table-driven benchmarks and creating hierarchical tests.
+// It also provides a way to share common setup and tear-down code:
+//
+//     func TestFoo(t *testing.T) {
+//         // <setup code>
+//         t.Run("A=1", func(t *testing.T) { ... })
+//         t.Run("A=2", func(t *testing.T) { ... })
+//         t.Run("B=1", func(t *testing.T) { ... })
+//         // <tear-down code>
+//     }
+//
+// Each subtest and sub-benchmark has a unique name: the combination of the name
+// of the top-level test and the sequence of names passed to Run, separated by
+// slashes, with an optional trailing sequence number for disambiguation.
+//
+// The argument to the -run and -bench command-line flags is a slash-separated
+// list of regular expressions that match each name element in turn.
+// For example:
+//
+//     go test -run Foo     # Run top-level tests matching "Foo".
+//     go test -run Foo/A=  # Run subtests of Foo matching "A=".
+//     go test -run /A=1    # Run all subtests of a top-level test matching "A=1".
+//
+// Subtests can also be used to control parallelism. A parent test will only
+// complete once all of its subtests complete. In this example, all tests are
+// run in parallel with each other, and only with each other, regardless of
+// other top-level tests that may be defined:
+//
+//     func TestGroupedParallel(t *testing.T) {
+//         for _, tc := range tests {
+//             tc := tc // capture range variable
+//             t.Run(tc.Name, func(t *testing.T) {
+//                 t.Parallel()
+//                 ...
+//             })
+//         }
+//     }
+//
+// Run does not return until parallel subtests have completed, providing a way
+// to clean up after a group of parallel tests:
+//
+//     func TestTeardownParallel(t *testing.T) {
+//         // This Run will not return until the parallel tests finish.
+//         t.Run("group", func(t *testing.T) {
+//             t.Run("Test1", parallelTest1)
+//             t.Run("Test2", parallelTest2)
+//             t.Run("Test3", parallelTest3)
+//         })
+//         // <tear-down code>
+//     }
+//
 // Main
 //
 // It is sometimes necessary for a test program to do extra setup or teardown
@@ -147,6 +202,7 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
+	"io"
 	"os"
 	"runtime"
 	"runtime/debug"
@@ -159,8 +215,8 @@ import (
 
 var (
 	// The short flag requests that tests run more quickly, but its functionality
-	// is provided by test writers themselves.  The testing package is just its
-	// home.  The all.bash installation script sets it to make installation more
+	// is provided by test writers themselves. The testing package is just its
+	// home. The all.bash installation script sets it to make installation more
 	// efficient, but by default the flag is off so a plain "go test" will do a
 	// full test of the package.
 	short = flag.Bool("test.short", false, "run smaller test suite to save time")
@@ -194,16 +250,23 @@ var (
 // common holds the elements common between T and B and
 // captures common methods such as Errorf.
 type common struct {
-	mu       sync.RWMutex // guards output and failed
+	mu       sync.RWMutex // guards output, failed, and done.
 	output   []byte       // Output generated by test or benchmark.
+	w        io.Writer    // For flushToParent.
+	chatty   bool         // A copy of the chatty flag.
 	failed   bool         // Test or benchmark has failed.
 	skipped  bool         // Test of benchmark has been skipped.
-	finished bool
+	finished bool         // Test function has completed.
+	done     bool         // Test is finished and all subtests have completed.
 
+	parent   *common
+	level    int       // Nesting depth of test or benchmark.
+	name     string    // Name of test or benchmark.
 	start    time.Time // Time test or benchmark started
 	duration time.Duration
-	self     interface{}      // To be sent on signal channel when done.
-	signal   chan interface{} // Output for serial tests.
+	barrier  chan bool // To signal parallel subtests they may start.
+	signal   chan bool // To signal a test is done.
+	sub      []*T      // Queue of subtests to be run in parallel.
 }
 
 // Short reports whether the -test.short flag is set.
@@ -250,6 +313,44 @@ func decorate(s string) string {
 	return buf.String()
 }
 
+// flushToParent writes c.output to the parent after first writing the header
+// with the given format and arguments.
+func (c *common) flushToParent(format string, args ...interface{}) {
+	p := c.parent
+	p.mu.Lock()
+	defer p.mu.Unlock()
+
+	fmt.Fprintf(p.w, format, args...)
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	io.Copy(p.w, bytes.NewReader(c.output))
+	c.output = c.output[:0]
+}
+
+type indenter struct {
+	c *common
+}
+
+func (w indenter) Write(b []byte) (n int, err error) {
+	n = len(b)
+	for len(b) > 0 {
+		end := bytes.IndexByte(b, '\n')
+		if end == -1 {
+			end = len(b)
+		} else {
+			end++
+		}
+		// An indent of 4 spaces will neatly align the dashes with the status
+		// indicator of the parent.
+		const indent = "    "
+		w.c.output = append(w.c.output, indent...)
+		w.c.output = append(w.c.output, b[:end]...)
+		b = b[end:]
+	}
+	return
+}
+
 // fmtDuration returns a string representing d in the form "87.00s".
 func fmtDuration(d time.Duration) string {
 	return fmt.Sprintf("%.2fs", d.Seconds())
@@ -281,7 +382,7 @@ var _ TB = (*T)(nil)
 var _ TB = (*B)(nil)
 
 // T is a type passed to Test functions to manage test state and support formatted test logs.
-// Logs are accumulated during execution and dumped to standard error when done.
+// Logs are accumulated during execution and dumped to standard output when done.
 //
 // A test ends when its Test function returns or calls any of the methods
 // FailNow, Fatal, Fatalf, SkipNow, Skip, or Skipf. Those methods, as well as
@@ -292,17 +393,23 @@ var _ TB = (*B)(nil)
 // may be called simultaneously from multiple goroutines.
 type T struct {
 	common
-	name          string // Name of test.
-	isParallel    bool
-	startParallel chan bool // Parallel tests will wait on this.
+	isParallel bool
+	context    *testContext // For running tests and subtests.
 }
 
 func (c *common) private() {}
 
 // Fail marks the function as having failed but continues execution.
 func (c *common) Fail() {
+	if c.parent != nil {
+		c.parent.Fail()
+	}
 	c.mu.Lock()
 	defer c.mu.Unlock()
+	// c.done needs to be locked to synchronize checks to c.done in parent tests.
+	if c.done {
+		panic("Fail in goroutine after " + c.name + " has completed")
+	}
 	c.failed = true
 }
 
@@ -336,9 +443,9 @@ func (c *common) FailNow() {
 	// This previous version duplicated code (those lines are in
 	// tRunner no matter what), but worse the goroutine teardown
 	// implicit in runtime.Goexit was not guaranteed to complete
-	// before the test exited.  If a test deferred an important cleanup
+	// before the test exited. If a test deferred an important cleanup
 	// function (like removing temporary files), there was no guarantee
-	// it would run on a test failure.  Because we send on c.signal during
+	// it would run on a test failure. Because we send on c.signal during
 	// a top-of-stack deferred function now, we know that the send
 	// only happens after any other stacked defers have completed.
 	c.finished = true
@@ -436,8 +543,13 @@ func (t *T) Parallel() {
 	// in the test duration. Record the elapsed time thus far and reset the
 	// timer afterwards.
 	t.duration += time.Since(t.start)
-	t.signal <- (*T)(nil) // Release main testing loop
-	<-t.startParallel     // Wait for serial tests to finish
+
+	// Add to the list of tests to be released by the parent.
+	t.parent.sub = append(t.parent.sub, t)
+
+	t.signal <- true   // Release calling test.
+	<-t.parent.barrier // Wait for the parent test to complete.
+	t.context.waitParallel()
 	t.start = time.Now()
 }
 
@@ -448,8 +560,8 @@ type InternalTest struct {
 	F    func(*T)
 }
 
-func tRunner(t *T, test *InternalTest) {
-	// When this goroutine is done, either because test.F(t)
+func tRunner(t *T, fn func(t *T)) {
+	// When this goroutine is done, either because fn(t)
 	// returned normally or because a test failure triggered
 	// a call to runtime.Goexit, record the duration and send
 	// a signal saying that the test is done.
@@ -465,14 +577,130 @@ func tRunner(t *T, test *InternalTest) {
 			t.report()
 			panic(err)
 		}
-		t.signal <- t
+
+		if len(t.sub) > 0 {
+			// Run parallel subtests.
+			// Decrease the running count for this test.
+			t.context.release()
+			// Release the parallel subtests.
+			close(t.barrier)
+			// Wait for subtests to complete.
+			for _, sub := range t.sub {
+				<-sub.signal
+			}
+			if !t.isParallel {
+				// Reacquire the count for sequential tests. See comment in Run.
+				t.context.waitParallel()
+			}
+		} else if t.isParallel {
+			// Only release the count for this test if it was run as a parallel
+			// test. See comment in Run method.
+			t.context.release()
+		}
+		t.report() // Report after all subtests have finished.
+
+		// Do not lock t.done to allow race detector to detect race in case
+		// the user does not appropriately synchronizes a goroutine.
+		t.done = true
+		t.signal <- true
 	}()
 
 	t.start = time.Now()
-	test.F(t)
+	fn(t)
 	t.finished = true
 }
 
+// Run runs f as a subtest of t called name. It reports whether f succeeded.
+// Run will block until all its parallel subtests have completed.
+func (t *T) Run(name string, f func(t *T)) bool {
+	testName, ok := t.context.match.fullName(&t.common, name)
+	if !ok {
+		return true
+	}
+	t = &T{
+		common: common{
+			barrier: make(chan bool),
+			signal:  make(chan bool),
+			name:    testName,
+			parent:  &t.common,
+			level:   t.level + 1,
+			chatty:  t.chatty,
+		},
+		context: t.context,
+	}
+	t.w = indenter{&t.common}
+
+	if t.chatty {
+		// Print directly to root's io.Writer so there is no delay.
+		root := t.parent
+		for ; root.parent != nil; root = root.parent {
+		}
+		fmt.Fprintf(root.w, "=== RUN   %s\n", t.name)
+	}
+	// Instead of reducing the running count of this test before calling the
+	// tRunner and increasing it afterwards, we rely on tRunner keeping the
+	// count correct. This ensures that a sequence of sequential tests runs
+	// without being preempted, even when their parent is a parallel test. This
+	// may especially reduce surprises if *parallel == 1.
+	go tRunner(t, f)
+	<-t.signal
+	return !t.failed
+}
+
+// testContext holds all fields that are common to all tests. This includes
+// synchronization primitives to run at most *parallel tests.
+type testContext struct {
+	match *matcher
+
+	mu sync.Mutex
+
+	// Channel used to signal tests that are ready to be run in parallel.
+	startParallel chan bool
+
+	// running is the number of tests currently running in parallel.
+	// This does not include tests that are waiting for subtests to complete.
+	running int
+
+	// numWaiting is the number tests waiting to be run in parallel.
+	numWaiting int
+
+	// maxParallel is a copy of the parallel flag.
+	maxParallel int
+}
+
+func newTestContext(maxParallel int, m *matcher) *testContext {
+	return &testContext{
+		match:         m,
+		startParallel: make(chan bool),
+		maxParallel:   maxParallel,
+		running:       1, // Set the count to 1 for the main (sequential) test.
+	}
+}
+
+func (c *testContext) waitParallel() {
+	c.mu.Lock()
+	if c.running < c.maxParallel {
+		c.running++
+		c.mu.Unlock()
+		return
+	}
+	c.numWaiting++
+	c.mu.Unlock()
+	<-c.startParallel
+}
+
+func (c *testContext) release() {
+	c.mu.Lock()
+	if c.numWaiting == 0 {
+		c.running--
+		c.mu.Unlock()
+		return
+	}
+	c.numWaiting--
+	c.mu.Unlock()
+	c.startParallel <- true // Pick a waiting test to be run.
+}
+
 // An internal function but exported because it is cross-package; part of the implementation
 // of the "go test" command.
 func Main(matchString func(pat, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample) {
@@ -514,27 +742,29 @@ func (m *M) Run() int {
 	testOk := RunTests(m.matchString, m.tests)
 	exampleOk := RunExamples(m.matchString, m.examples)
 	stopAlarm()
-	if !testOk || !exampleOk {
+	if !testOk || !exampleOk || !runBenchmarksInternal(m.matchString, m.benchmarks) {
 		fmt.Println("FAIL")
 		after()
 		return 1
 	}
 	fmt.Println("PASS")
-	RunBenchmarks(m.matchString, m.benchmarks)
 	after()
 	return 0
 }
 
 func (t *T) report() {
+	if t.parent == nil {
+		return
+	}
 	dstr := fmtDuration(t.duration)
-	format := "--- %s: %s (%s)\n%s"
+	format := "--- %s: %s (%s)\n"
 	if t.Failed() {
-		fmt.Printf(format, "FAIL", t.name, dstr, t.output)
-	} else if *chatty {
+		t.flushToParent(format, "FAIL", t.name, dstr)
+	} else if t.chatty {
 		if t.Skipped() {
-			fmt.Printf(format, "SKIP", t.name, dstr, t.output)
+			t.flushToParent(format, "SKIP", t.name, dstr)
 		} else {
-			fmt.Printf(format, "PASS", t.name, dstr, t.output)
+			t.flushToParent(format, "PASS", t.name, dstr)
 		}
 	}
 }
@@ -547,63 +777,26 @@ func RunTests(matchString func(pat, str string) (bool, error), tests []InternalT
 	}
 	for _, procs := range cpuList {
 		runtime.GOMAXPROCS(procs)
-		// We build a new channel tree for each run of the loop.
-		// collector merges in one channel all the upstream signals from parallel tests.
-		// If all tests pump to the same channel, a bug can occur where a test
-		// kicks off a goroutine that Fails, yet the test still delivers a completion signal,
-		// which skews the counting.
-		var collector = make(chan interface{})
-
-		numParallel := 0
-		startParallel := make(chan bool)
-
-		for i := 0; i < len(tests); i++ {
-			matched, err := matchString(*match, tests[i].Name)
-			if err != nil {
-				fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.run: %s\n", err)
-				os.Exit(1)
-			}
-			if !matched {
-				continue
-			}
-			testName := tests[i].Name
-			t := &T{
-				common: common{
-					signal: make(chan interface{}),
-				},
-				name:          testName,
-				startParallel: startParallel,
-			}
-			t.self = t
-			if *chatty {
-				fmt.Printf("=== RUN   %s\n", t.name)
-			}
-			go tRunner(t, &tests[i])
-			out := (<-t.signal).(*T)
-			if out == nil { // Parallel run.
-				go func() {
-					collector <- <-t.signal
-				}()
-				numParallel++
-				continue
-			}
-			t.report()
-			ok = ok && !out.Failed()
+		ctx := newTestContext(*parallel, newMatcher(matchString, *match, "-test.run"))
+		t := &T{
+			common: common{
+				signal:  make(chan bool),
+				barrier: make(chan bool),
+				w:       os.Stdout,
+				chatty:  *chatty,
+			},
+			context: ctx,
 		}
-
-		running := 0
-		for numParallel+running > 0 {
-			if running < *parallel && numParallel > 0 {
-				startParallel <- true
-				running++
-				numParallel--
-				continue
+		tRunner(t, func(t *T) {
+			for _, test := range tests {
+				t.Run(test.Name, test.F)
 			}
-			t := (<-collector).(*T)
-			t.report()
-			ok = ok && !t.Failed()
-			running--
-		}
+			// Run catching the signal rather than the tRunner as a separate
+			// goroutine to avoid adding a goroutine during the sequential
+			// phase as this pollutes the stacktrace output when aborting.
+			go func() { <-t.signal }()
+		})
+		ok = ok && !t.Failed()
 	}
 	return
 }
diff --git a/libgo/go/testing/testing_test.go b/libgo/go/testing/testing_test.go
index 87a5c16d6ed..45e44683b43 100644
--- a/libgo/go/testing/testing_test.go
+++ b/libgo/go/testing/testing_test.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The Go Authors.  All rights reserved.
+// Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/text/scanner/example_test.go b/libgo/go/text/scanner/example_test.go
index f8b51b7322b..f48c31daa0a 100644
--- a/libgo/go/text/scanner/example_test.go
+++ b/libgo/go/text/scanner/example_test.go
@@ -19,6 +19,7 @@ func Example() {
 		someParsable = text
 	}`
 	var s scanner.Scanner
+	s.Filename = "example"
 	s.Init(strings.NewReader(src))
 	var tok rune
 	for tok != scanner.EOF {
@@ -27,14 +28,14 @@ func Example() {
 	}
 
 	// Output:
-	// At position 3:4 : if
-	// At position 3:6 : a
-	// At position 3:8 : >
-	// At position 3:11 : 10
-	// At position 3:13 : {
-	// At position 4:15 : someParsable
-	// At position 4:17 : =
-	// At position 4:22 : text
-	// At position 5:3 : }
-	// At position 5:3 :
+	// At position example:3:4 : if
+	// At position example:3:6 : a
+	// At position example:3:8 : >
+	// At position example:3:11 : 10
+	// At position example:3:13 : {
+	// At position example:4:15 : someParsable
+	// At position example:4:17 : =
+	// At position example:4:22 : text
+	// At position example:5:3 : }
+	// At position example:5:3 :
 }
diff --git a/libgo/go/text/scanner/scanner.go b/libgo/go/text/scanner/scanner.go
index 0155800f34a..e085f8a7d95 100644
--- a/libgo/go/text/scanner/scanner.go
+++ b/libgo/go/text/scanner/scanner.go
@@ -4,12 +4,12 @@
 
 // Package scanner provides a scanner and tokenizer for UTF-8-encoded text.
 // It takes an io.Reader providing the source, which then can be tokenized
-// through repeated calls to the Scan function.  For compatibility with
+// through repeated calls to the Scan function. For compatibility with
 // existing tools, the NUL character is not allowed. If the first character
 // in the source is a UTF-8 encoded byte order mark (BOM), it is discarded.
 //
 // By default, a Scanner skips white space and Go comments and recognizes all
-// literals as defined by the Go language specification.  It may be
+// literals as defined by the Go language specification. It may be
 // customized to recognize only a subset of those literals and to recognize
 // different identifier and white space characters.
 package scanner
@@ -37,14 +37,11 @@ func (pos *Position) IsValid() bool { return pos.Line > 0 }
 
 func (pos Position) String() string {
 	s := pos.Filename
-	if pos.IsValid() {
-		if s != "" {
-			s += ":"
-		}
-		s += fmt.Sprintf("%d:%d", pos.Line, pos.Column)
-	}
 	if s == "" {
-		s = "???"
+		s = "<input>"
+	}
+	if pos.IsValid() {
+		s += fmt.Sprintf(":%d:%d", pos.Line, pos.Column)
 	}
 	return s
 }
diff --git a/libgo/go/text/scanner/scanner_test.go b/libgo/go/text/scanner/scanner_test.go
index 798bed7e92a..3e92d659ca0 100644
--- a/libgo/go/text/scanner/scanner_test.go
+++ b/libgo/go/text/scanner/scanner_test.go
@@ -451,37 +451,37 @@ func testError(t *testing.T, src, pos, msg string, tok rune) {
 }
 
 func TestError(t *testing.T) {
-	testError(t, "\x00", "1:1", "illegal character NUL", 0)
-	testError(t, "\x80", "1:1", "illegal UTF-8 encoding", utf8.RuneError)
-	testError(t, "\xff", "1:1", "illegal UTF-8 encoding", utf8.RuneError)
-
-	testError(t, "a\x00", "1:2", "illegal character NUL", Ident)
-	testError(t, "ab\x80", "1:3", "illegal UTF-8 encoding", Ident)
-	testError(t, "abc\xff", "1:4", "illegal UTF-8 encoding", Ident)
-
-	testError(t, `"a`+"\x00", "1:3", "illegal character NUL", String)
-	testError(t, `"ab`+"\x80", "1:4", "illegal UTF-8 encoding", String)
-	testError(t, `"abc`+"\xff", "1:5", "illegal UTF-8 encoding", String)
-
-	testError(t, "`a"+"\x00", "1:3", "illegal character NUL", String)
-	testError(t, "`ab"+"\x80", "1:4", "illegal UTF-8 encoding", String)
-	testError(t, "`abc"+"\xff", "1:5", "illegal UTF-8 encoding", String)
-
-	testError(t, `'\"'`, "1:3", "illegal char escape", Char)
-	testError(t, `"\'"`, "1:3", "illegal char escape", String)
-
-	testError(t, `01238`, "1:6", "illegal octal number", Int)
-	testError(t, `01238123`, "1:9", "illegal octal number", Int)
-	testError(t, `0x`, "1:3", "illegal hexadecimal number", Int)
-	testError(t, `0xg`, "1:3", "illegal hexadecimal number", Int)
-	testError(t, `'aa'`, "1:4", "illegal char literal", Char)
-
-	testError(t, `'`, "1:2", "literal not terminated", Char)
-	testError(t, `'`+"\n", "1:2", "literal not terminated", Char)
-	testError(t, `"abc`, "1:5", "literal not terminated", String)
-	testError(t, `"abc`+"\n", "1:5", "literal not terminated", String)
-	testError(t, "`abc\n", "2:1", "literal not terminated", String)
-	testError(t, `/*/`, "1:4", "comment not terminated", EOF)
+	testError(t, "\x00", "<input>:1:1", "illegal character NUL", 0)
+	testError(t, "\x80", "<input>:1:1", "illegal UTF-8 encoding", utf8.RuneError)
+	testError(t, "\xff", "<input>:1:1", "illegal UTF-8 encoding", utf8.RuneError)
+
+	testError(t, "a\x00", "<input>:1:2", "illegal character NUL", Ident)
+	testError(t, "ab\x80", "<input>:1:3", "illegal UTF-8 encoding", Ident)
+	testError(t, "abc\xff", "<input>:1:4", "illegal UTF-8 encoding", Ident)
+
+	testError(t, `"a`+"\x00", "<input>:1:3", "illegal character NUL", String)
+	testError(t, `"ab`+"\x80", "<input>:1:4", "illegal UTF-8 encoding", String)
+	testError(t, `"abc`+"\xff", "<input>:1:5", "illegal UTF-8 encoding", String)
+
+	testError(t, "`a"+"\x00", "<input>:1:3", "illegal character NUL", String)
+	testError(t, "`ab"+"\x80", "<input>:1:4", "illegal UTF-8 encoding", String)
+	testError(t, "`abc"+"\xff", "<input>:1:5", "illegal UTF-8 encoding", String)
+
+	testError(t, `'\"'`, "<input>:1:3", "illegal char escape", Char)
+	testError(t, `"\'"`, "<input>:1:3", "illegal char escape", String)
+
+	testError(t, `01238`, "<input>:1:6", "illegal octal number", Int)
+	testError(t, `01238123`, "<input>:1:9", "illegal octal number", Int)
+	testError(t, `0x`, "<input>:1:3", "illegal hexadecimal number", Int)
+	testError(t, `0xg`, "<input>:1:3", "illegal hexadecimal number", Int)
+	testError(t, `'aa'`, "<input>:1:4", "illegal char literal", Char)
+
+	testError(t, `'`, "<input>:1:2", "literal not terminated", Char)
+	testError(t, `'`+"\n", "<input>:1:2", "literal not terminated", Char)
+	testError(t, `"abc`, "<input>:1:5", "literal not terminated", String)
+	testError(t, `"abc`+"\n", "<input>:1:5", "literal not terminated", String)
+	testError(t, "`abc\n", "<input>:2:1", "literal not terminated", String)
+	testError(t, `/*/`, "<input>:1:4", "comment not terminated", EOF)
 }
 
 // An errReader returns (0, err) where err is not io.EOF.
diff --git a/libgo/go/text/tabwriter/example_test.go b/libgo/go/text/tabwriter/example_test.go
index 20443cb1ffb..422ec117adb 100644
--- a/libgo/go/text/tabwriter/example_test.go
+++ b/libgo/go/text/tabwriter/example_test.go
@@ -36,3 +36,38 @@ func ExampleWriter_Init() {
 	//     a     b       c         d.
 	//   123 12345 1234567 123456789.
 }
+
+func Example_elastic() {
+	// Observe how the b's and the d's, despite appearing in the
+	// second cell of each line, belong to different columns.
+	w := tabwriter.NewWriter(os.Stdout, 0, 0, 1, '.', tabwriter.AlignRight|tabwriter.Debug)
+	fmt.Fprintln(w, "a\tb\tc")
+	fmt.Fprintln(w, "aa\tbb\tcc")
+	fmt.Fprintln(w, "aaa\t") // trailing tab
+	fmt.Fprintln(w, "aaaa\tdddd\teeee")
+	w.Flush()
+
+	// output:
+	// ....a|..b|c
+	// ...aa|.bb|cc
+	// ..aaa|
+	// .aaaa|.dddd|eeee
+}
+
+func Example_trailingTab() {
+	// Observe that the third line has no trailing tab,
+	// so its final cell is not part of an aligned column.
+	const padding = 3
+	w := tabwriter.NewWriter(os.Stdout, 0, 0, padding, '-', tabwriter.AlignRight|tabwriter.Debug)
+	fmt.Fprintln(w, "a\tb\taligned\t")
+	fmt.Fprintln(w, "aa\tbb\taligned\t")
+	fmt.Fprintln(w, "aaa\tbbb\tunaligned") // no trailing tab
+	fmt.Fprintln(w, "aaaa\tbbbb\taligned\t")
+	w.Flush()
+
+	// output:
+	// ------a|------b|---aligned|
+	// -----aa|-----bb|---aligned|
+	// ----aaa|----bbb|unaligned
+	// ---aaaa|---bbbb|---aligned|
+}
diff --git a/libgo/go/text/tabwriter/tabwriter.go b/libgo/go/text/tabwriter/tabwriter.go
index c0c32d5deca..796e1e86995 100644
--- a/libgo/go/text/tabwriter/tabwriter.go
+++ b/libgo/go/text/tabwriter/tabwriter.go
@@ -33,18 +33,32 @@ type cell struct {
 // A Writer is a filter that inserts padding around tab-delimited
 // columns in its input to align them in the output.
 //
-// The Writer treats incoming bytes as UTF-8 encoded text consisting
-// of cells terminated by (horizontal or vertical) tabs or line
-// breaks (newline or formfeed characters). Cells in adjacent lines
-// constitute a column. The Writer inserts padding as needed to
-// make all cells in a column have the same width, effectively
-// aligning the columns. It assumes that all characters have the
-// same width except for tabs for which a tabwidth must be specified.
-// Note that cells are tab-terminated, not tab-separated: trailing
-// non-tab text at the end of a line does not form a column cell.
+// The Writer treats incoming bytes as UTF-8-encoded text consisting
+// of cells terminated by horizontal ('\t') or vertical ('\v') tabs,
+// and newline ('\n') or formfeed ('\f') characters; both newline and
+// formfeed act as line breaks.
+//
+// Tab-terminated cells in contiguous lines constitute a column. The
+// Writer inserts padding as needed to make all cells in a column have
+// the same width, effectively aligning the columns. It assumes that
+// all characters have the same width, except for tabs for which a
+// tabwidth must be specified. Column cells must be tab-terminated, not
+// tab-separated: non-tab terminated trailing text at the end of a line
+// forms a cell but that cell is not part of an aligned column.
+// For instance, in this example (where | stands for a horizontal tab):
+//
+//	aaaa|bbb|d
+//	aa  |b  |dd
+//	a   |
+//	aa  |cccc|eee
+//
+// the b and c are in distinct columns (the b column is not contiguous
+// all the way). The d and e are not in a column at all (there's no
+// terminating tab, nor would the column be contiguous).
 //
 // The Writer assumes that all Unicode code points have the same width;
-// this may not be true in some fonts.
+// this may not be true in some fonts or if the string contains combining
+// characters.
 //
 // If DiscardEmptyColumns is set, empty columns that are terminated
 // entirely by vertical (or "soft") tabs are discarded. Columns
@@ -64,9 +78,9 @@ type cell struct {
 // width of the escaped text is always computed excluding the Escape
 // characters.
 //
-// The formfeed character ('\f') acts like a newline but it also
-// terminates all columns in the current line (effectively calling
-// Flush). Cells in the next line start new columns. Unless found
+// The formfeed character acts like a newline but it also terminates
+// all columns in the current line (effectively calling Flush). Tab-
+// terminated cells in the next line start new columns. Unless found
 // inside an HTML tag or inside an escaped text segment, formfeed
 // characters appear as newlines in the output.
 //
@@ -448,8 +462,11 @@ func handlePanic(err *error, op string) {
 // that any data buffered in the Writer is written to output. Any
 // incomplete escape sequence at the end is considered
 // complete for formatting purposes.
-//
-func (b *Writer) Flush() (err error) {
+func (b *Writer) Flush() error {
+	return b.flush()
+}
+
+func (b *Writer) flush() (err error) {
 	defer b.reset() // even in the presence of errors
 	defer handlePanic(&err, "Flush")
 
@@ -464,8 +481,7 @@ func (b *Writer) Flush() (err error) {
 
 	// format contents of buffer
 	b.format(0, 0, len(b.lines))
-
-	return
+	return nil
 }
 
 var hbar = []byte("---\n")
diff --git a/libgo/go/text/template/doc.go b/libgo/go/text/template/doc.go
index df8c95f8c89..fe59e3f74e8 100644
--- a/libgo/go/text/template/doc.go
+++ b/libgo/go/text/template/doc.go
@@ -74,8 +74,9 @@ data, defined in detail in the corresponding sections that follow.
 /*
 
 	{{pipeline}}
-		The default textual representation of the value of the pipeline
-		is copied to the output.
+		The default textual representation (the same as would be
+		printed by fmt.Print) of the value of the pipeline is copied
+		to the output.
 
 	{{if pipeline}} T1 {{end}}
 		If the value of the pipeline is empty, no output is generated;
@@ -220,7 +221,7 @@ value (argument) or a function or method call, possibly with multiple arguments:
 		Functions and function names are described below.
 
 A pipeline may be "chained" by separating a sequence of commands with pipeline
-characters '|'. In a chained pipeline, the result of the each command is
+characters '|'. In a chained pipeline, the result of each command is
 passed as the last argument of the following command. The output of the final
 command in the pipeline is the value of the pipeline.
 
diff --git a/libgo/go/text/template/exec.go b/libgo/go/text/template/exec.go
index efe1817173f..8e5ad93ca6b 100644
--- a/libgo/go/text/template/exec.go
+++ b/libgo/go/text/template/exec.go
@@ -15,14 +15,21 @@ import (
 	"text/template/parse"
 )
 
+// maxExecDepth specifies the maximum stack depth of templates within
+// templates. This limit is only practically reached by accidentally
+// recursive template invocations. This limit allows us to return
+// an error instead of triggering a stack overflow.
+const maxExecDepth = 100000
+
 // state represents the state of an execution. It's not part of the
 // template so that multiple executions of the same template
 // can execute in parallel.
 type state struct {
-	tmpl *Template
-	wr   io.Writer
-	node parse.Node // current node, for errors
-	vars []variable // push-down stack of variable values.
+	tmpl  *Template
+	wr    io.Writer
+	node  parse.Node // current node, for errors
+	vars  []variable // push-down stack of variable values.
+	depth int        // the height of the stack of executing templates.
 }
 
 // variable holds the dynamic value of a variable such as $, $x etc.
@@ -164,7 +171,11 @@ func (t *Template) ExecuteTemplate(wr io.Writer, name string, data interface{})
 // execution stops, but partial results may already have been written to
 // the output writer.
 // A template may be executed safely in parallel.
-func (t *Template) Execute(wr io.Writer, data interface{}) (err error) {
+func (t *Template) Execute(wr io.Writer, data interface{}) error {
+	return t.execute(wr, data)
+}
+
+func (t *Template) execute(wr io.Writer, data interface{}) (err error) {
 	defer errRecover(&err)
 	value := reflect.ValueOf(data)
 	state := &state{
@@ -359,9 +370,13 @@ func (s *state) walkTemplate(dot reflect.Value, t *parse.TemplateNode) {
 	if tmpl == nil {
 		s.errorf("template %q not defined", t.Name)
 	}
+	if s.depth == maxExecDepth {
+		s.errorf("exceeded maximum template depth (%v)", maxExecDepth)
+	}
 	// Variables declared by the pipeline persist.
 	dot = s.evalPipeline(dot, t.Pipe)
 	newState := *s
+	newState.depth++
 	newState.tmpl = tmpl
 	// No dynamic scoping: template invocations inherit no variables.
 	newState.vars = []variable{{"$", dot}}
@@ -436,7 +451,7 @@ func (s *state) evalCommand(dot reflect.Value, cmd *parse.CommandNode, final ref
 
 // idealConstant is called to return the value of a number in a context where
 // we don't know the type. In that case, the syntax of the number tells us
-// its type, and we use Go rules to resolve.  Note there is no such thing as
+// its type, and we use Go rules to resolve. Note there is no such thing as
 // a uint ideal constant in this situation - the value must be of int type.
 func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
 	// These are ideal constants but we don't know the type
@@ -446,7 +461,7 @@ func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
 	switch {
 	case constant.IsComplex:
 		return reflect.ValueOf(constant.Complex128) // incontrovertible.
-	case constant.IsFloat && !isHexConstant(constant.Text) && strings.IndexAny(constant.Text, ".eE") >= 0:
+	case constant.IsFloat && !isHexConstant(constant.Text) && strings.ContainsAny(constant.Text, ".eE"):
 		return reflect.ValueOf(constant.Float64)
 	case constant.IsInt:
 		n := int(constant.Int64)
@@ -534,14 +549,14 @@ func (s *state) evalField(dot reflect.Value, fieldName string, node parse.Node,
 		return s.evalCall(dot, method, node, fieldName, args, final)
 	}
 	hasArgs := len(args) > 1 || final.IsValid()
-	// It's not a method; must be a field of a struct or an element of a map. The receiver must not be nil.
-	if isNil {
-		s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
-	}
+	// It's not a method; must be a field of a struct or an element of a map.
 	switch receiver.Kind() {
 	case reflect.Struct:
 		tField, ok := receiver.Type().FieldByName(fieldName)
 		if ok {
+			if isNil {
+				s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
+			}
 			field := receiver.FieldByIndex(tField.Index)
 			if tField.PkgPath != "" { // field is unexported
 				s.errorf("%s is an unexported field of struct type %s", fieldName, typ)
@@ -552,8 +567,10 @@ func (s *state) evalField(dot reflect.Value, fieldName string, node parse.Node,
 			}
 			return field
 		}
-		s.errorf("%s is not a field of struct type %s", fieldName, typ)
 	case reflect.Map:
+		if isNil {
+			s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
+		}
 		// If it's a map, attempt to use the field name as a key.
 		nameVal := reflect.ValueOf(fieldName)
 		if nameVal.Type().AssignableTo(receiver.Type().Key()) {
@@ -584,7 +601,7 @@ var (
 )
 
 // evalCall executes a function or method call. If it's a method, fun already has the receiver bound, so
-// it looks just like a function call.  The arg list, if non-nil, includes (in the manner of the shell), arg[0]
+// it looks just like a function call. The arg list, if non-nil, includes (in the manner of the shell), arg[0]
 // as the function itself.
 func (s *state) evalCall(dot, fun reflect.Value, node parse.Node, name string, args []parse.Node, final reflect.Value) reflect.Value {
 	if args != nil {
diff --git a/libgo/go/text/template/exec_test.go b/libgo/go/text/template/exec_test.go
index e507e917fe5..3ef065edcfd 100644
--- a/libgo/go/text/template/exec_test.go
+++ b/libgo/go/text/template/exec_test.go
@@ -1280,3 +1280,33 @@ func TestBlock(t *testing.T) {
 		t.Errorf("got %q, want %q", got, want2)
 	}
 }
+
+// Check that calling an invalid field on nil pointer prints
+// a field error instead of a distracting nil pointer error.
+// https://golang.org/issue/15125
+func TestMissingFieldOnNil(t *testing.T) {
+	tmpl := Must(New("tmpl").Parse("{{.MissingField}}"))
+	var d *T
+	err := tmpl.Execute(ioutil.Discard, d)
+	got := "<nil>"
+	if err != nil {
+		got = err.Error()
+	}
+	want := "can't evaluate field MissingField in type *template.T"
+	if !strings.HasSuffix(got, want) {
+		t.Errorf("got error %q, want %q", got, want)
+	}
+}
+
+func TestMaxExecDepth(t *testing.T) {
+	tmpl := Must(New("tmpl").Parse(`{{template "tmpl" .}}`))
+	err := tmpl.Execute(ioutil.Discard, nil)
+	got := "<nil>"
+	if err != nil {
+		got = err.Error()
+	}
+	const want = "exceeded maximum template depth"
+	if !strings.Contains(got, want) {
+		t.Errorf("got error %q; want %q", got, want)
+	}
+}
diff --git a/libgo/go/text/template/funcs.go b/libgo/go/text/template/funcs.go
index 49e9e7419a4..cd0b82b243d 100644
--- a/libgo/go/text/template/funcs.go
+++ b/libgo/go/text/template/funcs.go
@@ -142,7 +142,7 @@ func prepareArg(value reflect.Value, argType reflect.Type) (reflect.Value, error
 // Indexing.
 
 // index returns the result of indexing its first argument by the following
-// arguments.  Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
+// arguments. Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
 // indexed item must be a map, slice, or array.
 func index(item interface{}, indices ...interface{}) (interface{}, error) {
 	v := reflect.ValueOf(item)
@@ -322,7 +322,6 @@ const (
 	complexKind
 	intKind
 	floatKind
-	integerKind
 	stringKind
 	uintKind
 )
@@ -515,7 +514,7 @@ func HTMLEscape(w io.Writer, b []byte) {
 // HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.
 func HTMLEscapeString(s string) string {
 	// Avoid allocation if we can.
-	if strings.IndexAny(s, `'"&<>`) < 0 {
+	if !strings.ContainsAny(s, `'"&<>`) {
 		return s
 	}
 	var b bytes.Buffer
diff --git a/libgo/go/text/template/helper.go b/libgo/go/text/template/helper.go
index 787ca62e5f3..9e0200c3525 100644
--- a/libgo/go/text/template/helper.go
+++ b/libgo/go/text/template/helper.go
@@ -29,6 +29,11 @@ func Must(t *Template, err error) *Template {
 // the named files. The returned template's name will have the base name and
 // parsed contents of the first file. There must be at least one file.
 // If an error occurs, parsing stops and the returned *Template is nil.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+// For instance, ParseFiles("a/foo", "b/foo") stores "b/foo" as the template
+// named "foo", while "a/foo" is unavailable.
 func ParseFiles(filenames ...string) (*Template, error) {
 	return parseFiles(nil, filenames...)
 }
@@ -41,6 +46,9 @@ func ParseFiles(filenames ...string) (*Template, error) {
 // of the (base) names of the files. If it does not, depending on t's
 // contents before calling ParseFiles, t.Execute may fail. In that
 // case use t.ExecuteTemplate to execute a valid template.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
 func (t *Template) ParseFiles(filenames ...string) (*Template, error) {
 	t.init()
 	return parseFiles(t, filenames...)
@@ -88,6 +96,9 @@ func parseFiles(t *Template, filenames ...string) (*Template, error) {
 // returned template will have the (base) name and (parsed) contents of the
 // first file matched by the pattern. ParseGlob is equivalent to calling
 // ParseFiles with the list of files matched by the pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
 func ParseGlob(pattern string) (*Template, error) {
 	return parseGlob(nil, pattern)
 }
@@ -97,6 +108,9 @@ func ParseGlob(pattern string) (*Template, error) {
 // processed by filepath.Glob and must match at least one file. ParseGlob is
 // equivalent to calling t.ParseFiles with the list of files matched by the
 // pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
 func (t *Template) ParseGlob(pattern string) (*Template, error) {
 	t.init()
 	return parseGlob(t, pattern)
diff --git a/libgo/go/text/template/multi_test.go b/libgo/go/text/template/multi_test.go
index a8342f50aa5..c8723cb7a8b 100644
--- a/libgo/go/text/template/multi_test.go
+++ b/libgo/go/text/template/multi_test.go
@@ -4,7 +4,7 @@
 
 package template
 
-// Tests for mulitple-template parsing and execution.
+// Tests for multiple-template parsing and execution.
 
 import (
 	"bytes"
diff --git a/libgo/go/text/template/parse/lex.go b/libgo/go/text/template/parse/lex.go
index ea93e051425..079c0ea6f71 100644
--- a/libgo/go/text/template/parse/lex.go
+++ b/libgo/go/text/template/parse/lex.go
@@ -155,7 +155,7 @@ func (l *lexer) ignore() {
 
 // accept consumes the next rune if it's from the valid set.
 func (l *lexer) accept(valid string) bool {
-	if strings.IndexRune(valid, l.next()) >= 0 {
+	if strings.ContainsRune(valid, l.next()) {
 		return true
 	}
 	l.backup()
@@ -164,7 +164,7 @@ func (l *lexer) accept(valid string) bool {
 
 // acceptRun consumes a run of runes from the valid set.
 func (l *lexer) acceptRun(valid string) {
-	for strings.IndexRune(valid, l.next()) >= 0 {
+	for strings.ContainsRune(valid, l.next()) {
 	}
 	l.backup()
 }
diff --git a/libgo/go/text/template/parse/parse.go b/libgo/go/text/template/parse/parse.go
index dc56cf7aa0c..86705e5a379 100644
--- a/libgo/go/text/template/parse/parse.go
+++ b/libgo/go/text/template/parse/parse.go
@@ -48,12 +48,12 @@ func (t *Tree) Copy() *Tree {
 // templates described in the argument string. The top-level template will be
 // given the specified name. If an error is encountered, parsing stops and an
 // empty map is returned with the error.
-func Parse(name, text, leftDelim, rightDelim string, funcs ...map[string]interface{}) (treeSet map[string]*Tree, err error) {
-	treeSet = make(map[string]*Tree)
+func Parse(name, text, leftDelim, rightDelim string, funcs ...map[string]interface{}) (map[string]*Tree, error) {
+	treeSet := make(map[string]*Tree)
 	t := New(name)
 	t.text = text
-	_, err = t.Parse(text, leftDelim, rightDelim, treeSet, funcs...)
-	return
+	_, err := t.Parse(text, leftDelim, rightDelim, treeSet, funcs...)
+	return treeSet, err
 }
 
 // next returns the next token.
@@ -556,7 +556,7 @@ func (t *Tree) blockControl() Node {
 
 // Template:
 //	{{template stringValue pipeline}}
-// Template keyword is past.  The name must be something that can evaluate
+// Template keyword is past. The name must be something that can evaluate
 // to a string.
 func (t *Tree) templateControl() Node {
 	const context = "template clause"
diff --git a/libgo/go/text/template/parse/parse_test.go b/libgo/go/text/template/parse/parse_test.go
index b4512d31600..9d856bcb3df 100644
--- a/libgo/go/text/template/parse/parse_test.go
+++ b/libgo/go/text/template/parse/parse_test.go
@@ -76,7 +76,7 @@ var numberTests = []numberTest{
 
 func TestNumberParse(t *testing.T) {
 	for _, test := range numberTests {
-		// If fmt.Sscan thinks it's complex, it's complex.  We can't trust the output
+		// If fmt.Sscan thinks it's complex, it's complex. We can't trust the output
 		// because imaginary comes out as a number.
 		var c complex128
 		typ := itemNumber
diff --git a/libgo/go/time/example_test.go b/libgo/go/time/example_test.go
index f76fdcd4d03..4170d5110d0 100644
--- a/libgo/go/time/example_test.go
+++ b/libgo/go/time/example_test.go
@@ -1,4 +1,4 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
+// Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/time/format.go b/libgo/go/time/format.go
index e616feb048f..c2ae7930203 100644
--- a/libgo/go/time/format.go
+++ b/libgo/go/time/format.go
@@ -23,7 +23,7 @@ import "errors"
 // compatibility with fixed-width Unix time formats.
 //
 // A decimal point followed by one or more zeros represents a fractional
-// second, printed to the given number of decimal places.  A decimal point
+// second, printed to the given number of decimal places. A decimal point
 // followed by one or more nines represents a fractional second, printed to
 // the given number of decimal places, with trailing zeros removed.
 // When parsing (only), the input may contain a fractional second
@@ -37,7 +37,7 @@ import "errors"
 //	-07    ±hh
 // Replacing the sign in the format with a Z triggers
 // the ISO 8601 behavior of printing Z instead of an
-// offset for the UTC zone.  Thus:
+// offset for the UTC zone. Thus:
 //	Z0700  Z or ±hhmm
 //	Z07:00 Z or ±hh:mm
 //	Z07    Z or ±hh
@@ -51,6 +51,9 @@ import "errors"
 // use of "GMT" in that case.
 // In general RFC1123Z should be used instead of RFC1123 for servers
 // that insist on that format, and RFC3339 should be preferred for new protocols.
+// RFC822, RFC822Z, RFC1123, and RFC1123Z are useful for formatting;
+// when used with time.Parse they do not accept all the time formats
+// permitted by the RFCs.
 const (
 	ANSIC       = "Mon Jan _2 15:04:05 2006"
 	UnixDate    = "Mon Jan _2 15:04:05 MST 2006"
@@ -551,7 +554,7 @@ func (t Time) AppendFormat(b []byte, layout string) []byte {
 				b = append(b, "am"...)
 			}
 		case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumColonTZ, stdNumSecondsTz, stdNumShortTZ, stdNumColonSecondsTZ:
-			// Ugly special case.  We cheat and take the "Z" variants
+			// Ugly special case. We cheat and take the "Z" variants
 			// to mean "the time zone as formatted for ISO 8601".
 			if offset == 0 && (std == stdISO8601TZ || std == stdISO8601ColonTZ || std == stdISO8601SecondsTZ || std == stdISO8601ShortTZ || std == stdISO8601ColonSecondsTZ) {
 				b = append(b, 'Z')
diff --git a/libgo/go/time/format_test.go b/libgo/go/time/format_test.go
index a2592e2ceb5..ed5509b3021 100644
--- a/libgo/go/time/format_test.go
+++ b/libgo/go/time/format_test.go
@@ -449,7 +449,7 @@ func TestParseErrors(t *testing.T) {
 		_, err := Parse(test.format, test.value)
 		if err == nil {
 			t.Errorf("expected error for %q %q", test.format, test.value)
-		} else if strings.Index(err.Error(), test.expect) < 0 {
+		} else if !strings.Contains(err.Error(), test.expect) {
 			t.Errorf("expected error with %q for %q %q; got %s", test.expect, test.format, test.value, err)
 		}
 	}
diff --git a/libgo/go/time/genzabbrs.go b/libgo/go/time/genzabbrs.go
index 9eb0728a42e..6281f73ce4a 100644
--- a/libgo/go/time/genzabbrs.go
+++ b/libgo/go/time/genzabbrs.go
@@ -30,7 +30,7 @@ var filename = flag.String("output", "zoneinfo_abbrs_windows.go", "output file n
 // getAbbrs finds timezone abbreviations (standard and daylight saving time)
 // for location l.
 func getAbbrs(l *time.Location) (st, dt string) {
-	t := time.Date(time.Now().Year(), 0, 0, 0, 0, 0, 0, l)
+	t := time.Date(time.Now().Year(), 0, 1, 0, 0, 0, 0, l)
 	abbr1, off1 := t.Zone()
 	for i := 0; i < 12; i++ {
 		t = t.AddDate(0, 1, 0)
diff --git a/libgo/go/time/sleep.go b/libgo/go/time/sleep.go
index e7a2ee20598..73114f5eecd 100644
--- a/libgo/go/time/sleep.go
+++ b/libgo/go/time/sleep.go
@@ -24,7 +24,7 @@ type runtimeTimer struct {
 
 // when is a helper function for setting the 'when' field of a runtimeTimer.
 // It returns what the time will be, in nanoseconds, Duration d in the future.
-// If d is negative, it is ignored.  If the returned value would be less than
+// If d is negative, it is ignored. If the returned value would be less than
 // zero because of an overflow, MaxInt64 is returned.
 func when(d Duration) int64 {
 	if d <= 0 {
@@ -54,6 +54,14 @@ type Timer struct {
 // expired or been stopped.
 // Stop does not close the channel, to prevent a read from the channel succeeding
 // incorrectly.
+//
+// To prevent the timer firing after a call to Stop,
+// check the return value and drain the channel. For example:
+// 	if !t.Stop() {
+// 		<-t.C
+// 	}
+// This cannot be done concurrent to other receives from the Timer's
+// channel.
 func (t *Timer) Stop() bool {
 	if t.r.f == nil {
 		panic("time: Stop called on uninitialized Timer")
@@ -80,6 +88,20 @@ func NewTimer(d Duration) *Timer {
 // Reset changes the timer to expire after duration d.
 // It returns true if the timer had been active, false if the timer had
 // expired or been stopped.
+//
+// To reuse an active timer, always call its Stop method first and—if it had
+// expired—drain the value from its channel. For example:
+// 	if !t.Stop() {
+// 		<-t.C
+// 	}
+// 	t.Reset(d)
+// This should not be done concurrent to other receives from the Timer's
+// channel.
+//
+// Note that it is not possible to use Reset's return value correctly, as there
+// is a race condition between draining the channel and the new timer expiring.
+// Reset should always be used in concert with Stop, as described above.
+// The return value exists to preserve compatibility with existing programs.
 func (t *Timer) Reset(d Duration) bool {
 	if t.r.f == nil {
 		panic("time: Reset called on uninitialized Timer")
@@ -106,6 +128,9 @@ func sendTime(c interface{}, seq uintptr) {
 // After waits for the duration to elapse and then sends the current time
 // on the returned channel.
 // It is equivalent to NewTimer(d).C.
+// The underlying Timer is not recovered by the garbage collector
+// until the timer fires. If efficiency is a concern, use NewTimer
+// instead and call Timer.Stop if the timer is no longer needed.
 func After(d Duration) <-chan Time {
 	return NewTimer(d).C
 }
diff --git a/libgo/go/time/sys_plan9.go b/libgo/go/time/sys_plan9.go
index 8484729448e..11365a791f7 100644
--- a/libgo/go/time/sys_plan9.go
+++ b/libgo/go/time/sys_plan9.go
@@ -55,9 +55,9 @@ func closefd(fd uintptr) {
 }
 
 func preadn(fd uintptr, buf []byte, off int) error {
-	whence := 0
+	whence := seekStart
 	if off < 0 {
-		whence = 2
+		whence = seekEnd
 	}
 	if _, err := syscall.Seek(int(fd), int64(off), whence); err != nil {
 		return err
diff --git a/libgo/go/time/sys_unix.go b/libgo/go/time/sys_unix.go
index e592415daa5..91d54c9ffd0 100644
--- a/libgo/go/time/sys_unix.go
+++ b/libgo/go/time/sys_unix.go
@@ -55,9 +55,9 @@ func closefd(fd uintptr) {
 }
 
 func preadn(fd uintptr, buf []byte, off int) error {
-	whence := 0
+	whence := seekStart
 	if off < 0 {
-		whence = 2
+		whence = seekEnd
 	}
 	if _, err := syscall.Seek(int(fd), int64(off), whence); err != nil {
 		return err
diff --git a/libgo/go/time/sys_windows.go b/libgo/go/time/sys_windows.go
index de63b4bf4bb..a4a068f7849 100644
--- a/libgo/go/time/sys_windows.go
+++ b/libgo/go/time/sys_windows.go
@@ -52,9 +52,9 @@ func closefd(fd uintptr) {
 }
 
 func preadn(fd uintptr, buf []byte, off int) error {
-	whence := 0
+	whence := seekStart
 	if off < 0 {
-		whence = 2
+		whence = seekEnd
 	}
 	if _, err := syscall.Seek(syscall.Handle(fd), int64(off), whence); err != nil {
 		return err
diff --git a/libgo/go/time/tick.go b/libgo/go/time/tick.go
index 196e8ac61a6..3d693206a53 100644
--- a/libgo/go/time/tick.go
+++ b/libgo/go/time/tick.go
@@ -39,7 +39,7 @@ func NewTicker(d Duration) *Ticker {
 	return t
 }
 
-// Stop turns off a ticker.  After Stop, no more ticks will be sent.
+// Stop turns off a ticker. After Stop, no more ticks will be sent.
 // Stop does not close the channel, to prevent a read from the channel succeeding
 // incorrectly.
 func (t *Ticker) Stop() {
@@ -50,6 +50,7 @@ func (t *Ticker) Stop() {
 // channel only. While Tick is useful for clients that have no need to shut down
 // the Ticker, be aware that without a way to shut it down the underlying
 // Ticker cannot be recovered by the garbage collector; it "leaks".
+// Unlike NewTicker, Tick will return nil if d <= 0.
 func Tick(d Duration) <-chan Time {
 	if d <= 0 {
 		return nil
diff --git a/libgo/go/time/tick_test.go b/libgo/go/time/tick_test.go
index 32f4740ad93..2ab77f60255 100644
--- a/libgo/go/time/tick_test.go
+++ b/libgo/go/time/tick_test.go
@@ -35,7 +35,7 @@ func TestTicker(t *testing.T) {
 	}
 }
 
-// Test that a bug tearing down a ticker has been fixed.  This routine should not deadlock.
+// Test that a bug tearing down a ticker has been fixed. This routine should not deadlock.
 func TestTeardown(t *testing.T) {
 	Delta := 100 * Millisecond
 	if testing.Short() {
diff --git a/libgo/go/time/time.go b/libgo/go/time/time.go
index ef4ba5842de..c31de357d58 100644
--- a/libgo/go/time/time.go
+++ b/libgo/go/time/time.go
@@ -12,8 +12,8 @@ import "errors"
 // A Time represents an instant in time with nanosecond precision.
 //
 // Programs using times should typically store and pass them as values,
-// not pointers.  That is, time variables and struct fields should be of
-// type time.Time, not *time.Time.  A Time value can be used by
+// not pointers. That is, time variables and struct fields should be of
+// type time.Time, not *time.Time. A Time value can be used by
 // multiple goroutines simultaneously.
 //
 // Time instants can be compared using the Before, After, and Equal methods.
@@ -146,7 +146,7 @@ func (d Weekday) String() string { return days[d] }
 // 00:00:00 UTC, which would be 12-31-(-1) 19:00:00 in New York.
 //
 // The zero Time value does not force a specific epoch for the time
-// representation.  For example, to use the Unix epoch internally, we
+// representation. For example, to use the Unix epoch internally, we
 // could define that to distinguish a zero value from Jan 1 1970, that
 // time would be represented by sec=-1, nsec=1e9.  However, it does
 // suggest a representation, namely using 1-1-1 00:00:00 UTC as the
@@ -155,17 +155,17 @@ func (d Weekday) String() string { return days[d] }
 // The Add and Sub computations are oblivious to the choice of epoch.
 //
 // The presentation computations - year, month, minute, and so on - all
-// rely heavily on division and modulus by positive constants.  For
+// rely heavily on division and modulus by positive constants. For
 // calendrical calculations we want these divisions to round down, even
 // for negative values, so that the remainder is always positive, but
 // Go's division (like most hardware division instructions) rounds to
-// zero.  We can still do those computations and then adjust the result
+// zero. We can still do those computations and then adjust the result
 // for a negative numerator, but it's annoying to write the adjustment
-// over and over.  Instead, we can change to a different epoch so long
+// over and over. Instead, we can change to a different epoch so long
 // ago that all the times we care about will be positive, and then round
-// to zero and round down coincide.  These presentation routines already
+// to zero and round down coincide. These presentation routines already
 // have to add the zone offset, so adding the translation to the
-// alternate epoch is cheap.  For example, having a non-negative time t
+// alternate epoch is cheap. For example, having a non-negative time t
 // means that we can write
 //
 //	sec = t % 60
@@ -181,9 +181,9 @@ func (d Weekday) String() string { return days[d] }
 //
 // The calendar runs on an exact 400 year cycle: a 400-year calendar
 // printed for 1970-2469 will apply as well to 2370-2769.  Even the days
-// of the week match up.  It simplifies the computations to choose the
+// of the week match up. It simplifies the computations to choose the
 // cycle boundaries so that the exceptional years are always delayed as
-// long as possible.  That means choosing a year equal to 1 mod 400, so
+// long as possible. That means choosing a year equal to 1 mod 400, so
 // that the first leap year is the 4th year, the first missed leap year
 // is the 100th year, and the missed missed leap year is the 400th year.
 // So we'd prefer instead to print a calendar for 2001-2400 and reuse it
@@ -209,7 +209,7 @@ func (d Weekday) String() string { return days[d] }
 // routines would then be invalid when displaying the epoch in time zones
 // west of UTC, since it is year 0.  It doesn't seem tenable to say that
 // printing the zero time correctly isn't supported in half the time
-// zones.  By comparison, it's reasonable to mishandle some times in
+// zones. By comparison, it's reasonable to mishandle some times in
 // the year -292277022399.
 //
 // All this is opaque to clients of the API and can be changed if a
@@ -225,9 +225,6 @@ const (
 	// Assumed by the unixToInternal computation below.
 	internalYear = 1
 
-	// The year of the zero Unix time.
-	unixYear = 1970
-
 	// Offsets to convert between internal and absolute or Unix times.
 	absoluteToInternal int64 = (absoluteZeroYear - internalYear) * 365.2425 * secondsPerDay
 	internalToAbsolute       = -absoluteToInternal
@@ -425,7 +422,7 @@ func (t Time) YearDay() int {
 }
 
 // A Duration represents the elapsed time between two instants
-// as an int64 nanosecond count.  The representation limits the
+// as an int64 nanosecond count. The representation limits the
 // largest representable duration to approximately 290 years.
 type Duration int64
 
@@ -434,7 +431,7 @@ const (
 	maxDuration Duration = 1<<63 - 1
 )
 
-// Common durations.  There is no definition for units of Day or larger
+// Common durations. There is no definition for units of Day or larger
 // to avoid confusion across daylight savings time zone transitions.
 //
 // To count the number of units in a Duration, divide:
@@ -455,10 +452,9 @@ const (
 )
 
 // String returns a string representing the duration in the form "72h3m0.5s".
-// Leading zero units are omitted.  As a special case, durations less than one
+// Leading zero units are omitted. As a special case, durations less than one
 // second format use a smaller unit (milli-, micro-, or nanoseconds) to ensure
-// that the leading digit is non-zero.  The zero duration formats as 0,
-// with no unit.
+// that the leading digit is non-zero. The zero duration formats as 0s.
 func (d Duration) String() string {
 	// Largest time is 2540400h10m10.000000000s
 	var buf [32]byte
@@ -479,7 +475,7 @@ func (d Duration) String() string {
 		w--
 		switch {
 		case u == 0:
-			return "0"
+			return "0s"
 		case u < uint64(Microsecond):
 			// print nanoseconds
 			prec = 0
@@ -609,7 +605,7 @@ func (d Duration) Hours() float64 {
 // Add returns the time t+d.
 func (t Time) Add(d Duration) Time {
 	t.sec += int64(d / 1e9)
-	nsec := int32(t.nsec) + int32(d%1e9)
+	nsec := t.nsec + int32(d%1e9)
 	if nsec >= 1e9 {
 		t.sec++
 		nsec -= 1e9
@@ -626,7 +622,7 @@ func (t Time) Add(d Duration) Time {
 // will be returned.
 // To compute t-d for a duration d, use t.Add(-d).
 func (t Time) Sub(u Time) Duration {
-	d := Duration(t.sec-u.sec)*Second + Duration(int32(t.nsec)-int32(u.nsec))
+	d := Duration(t.sec-u.sec)*Second + Duration(t.nsec-u.nsec)
 	// Check for overflow or underflow.
 	switch {
 	case u.Add(d).Equal(t):
@@ -749,7 +745,7 @@ func absDate(abs uint64, full bool) (year int, month Month, day int, yday int) {
 }
 
 // daysBefore[m] counts the number of days in a non-leap year
-// before month m begins.  There is an entry for m=12, counting
+// before month m begins. There is an entry for m=12, counting
 // the number of days before January of next year (365).
 var daysBefore = [...]int32{
 	0,
@@ -945,10 +941,11 @@ func (t Time) MarshalJSON() ([]byte, error) {
 
 // UnmarshalJSON implements the json.Unmarshaler interface.
 // The time is expected to be a quoted string in RFC 3339 format.
-func (t *Time) UnmarshalJSON(data []byte) (err error) {
+func (t *Time) UnmarshalJSON(data []byte) error {
 	// Fractional seconds are handled implicitly by Parse.
+	var err error
 	*t, err = Parse(`"`+RFC3339+`"`, string(data))
-	return
+	return err
 }
 
 // MarshalText implements the encoding.TextMarshaler interface.
@@ -964,10 +961,11 @@ func (t Time) MarshalText() ([]byte, error) {
 
 // UnmarshalText implements the encoding.TextUnmarshaler interface.
 // The time is expected to be in RFC 3339 format.
-func (t *Time) UnmarshalText(data []byte) (err error) {
+func (t *Time) UnmarshalText(data []byte) error {
 	// Fractional seconds are handled implicitly by Parse.
+	var err error
 	*t, err = Parse(RFC3339, string(data))
-	return
+	return err
 }
 
 // Unix returns the local Time corresponding to the given Unix time,
@@ -1019,7 +1017,7 @@ func norm(hi, lo, base int) (nhi, nlo int) {
 //
 // A daylight savings time transition skips or repeats times.
 // For example, in the United States, March 13, 2011 2:15am never occurred,
-// while November 6, 2011 1:15am occurred twice.  In such cases, the
+// while November 6, 2011 1:15am occurred twice. In such cases, the
 // choice of time zone, and therefore the time, is not well-defined.
 // Date returns a time that is correct in one of the two zones involved
 // in the transition, but it does not guarantee which.
@@ -1126,7 +1124,7 @@ func (t Time) Round(d Duration) Time {
 // but it's still here in case we change our minds.
 func div(t Time, d Duration) (qmod2 int, r Duration) {
 	neg := false
-	nsec := int32(t.nsec)
+	nsec := t.nsec
 	if t.sec < 0 {
 		// Operate on absolute value.
 		neg = true
@@ -1160,7 +1158,7 @@ func div(t Time, d Duration) (qmod2 int, r Duration) {
 		tmp := (sec >> 32) * 1e9
 		u1 := tmp >> 32
 		u0 := tmp << 32
-		tmp = uint64(sec&0xFFFFFFFF) * 1e9
+		tmp = (sec & 0xFFFFFFFF) * 1e9
 		u0x, u0 := u0, u0+tmp
 		if u0 < u0x {
 			u1++
diff --git a/libgo/go/time/time_test.go b/libgo/go/time/time_test.go
index a925e98a838..b7ebb372967 100644
--- a/libgo/go/time/time_test.go
+++ b/libgo/go/time/time_test.go
@@ -22,7 +22,7 @@ import (
 // the subsequent tests fail.
 func TestZoneData(t *testing.T) {
 	lt := Now()
-	// PST is 8 hours west, PDT is 7 hours west.  We could use the name but it's not unique.
+	// PST is 8 hours west, PDT is 7 hours west. We could use the name but it's not unique.
 	if name, off := lt.Zone(); off != -8*60*60 && off != -7*60*60 {
 		t.Errorf("Unable to find US Pacific time zone data for testing; time zone is %q offset %d", name, off)
 		t.Error("Likely problem: the time zone files have not been installed.")
@@ -533,7 +533,7 @@ var durationTests = []struct {
 	str string
 	d   Duration
 }{
-	{"0", 0},
+	{"0s", 0},
 	{"1ns", 1 * Nanosecond},
 	{"1.1µs", 1100 * Nanosecond},
 	{"2.2ms", 2200 * Microsecond},
diff --git a/libgo/go/time/zoneinfo_abbrs_windows.go b/libgo/go/time/zoneinfo_abbrs_windows.go
index 51a1a2f66d8..344a891d1a4 100644
--- a/libgo/go/time/zoneinfo_abbrs_windows.go
+++ b/libgo/go/time/zoneinfo_abbrs_windows.go
@@ -22,9 +22,10 @@ var abbrs = map[string]abbr{
 	"Namibia Standard Time":           {"WAT", "WAST"},   // Africa/Windhoek
 	"Alaskan Standard Time":           {"AKST", "AKDT"},  // America/Anchorage
 	"Paraguay Standard Time":          {"PYT", "PYST"},   // America/Asuncion
-	"Bahia Standard Time":             {"BRT", "BRST"},   // America/Bahia
+	"Bahia Standard Time":             {"BRT", "BRT"},    // America/Bahia
 	"SA Pacific Standard Time":        {"COT", "COT"},    // America/Bogota
 	"Argentina Standard Time":         {"ART", "ART"},    // America/Buenos_Aires
+	"Eastern Standard Time (Mexico)":  {"EST", "EST"},    // America/Cancun
 	"Venezuela Standard Time":         {"VET", "VET"},    // America/Caracas
 	"SA Eastern Standard Time":        {"GFT", "GFT"},    // America/Cayenne
 	"Central Standard Time":           {"CST", "CDT"},    // America/Chicago
@@ -38,21 +39,22 @@ var abbrs = map[string]abbr{
 	"SA Western Standard Time":        {"BOT", "BOT"},    // America/La_Paz
 	"Pacific Standard Time":           {"PST", "PDT"},    // America/Los_Angeles
 	"Central Standard Time (Mexico)":  {"CST", "CDT"},    // America/Mexico_City
-	"Montevideo Standard Time":        {"UYT", "UYST"},   // America/Montevideo
+	"Montevideo Standard Time":        {"UYT", "UYT"},    // America/Montevideo
 	"Eastern Standard Time":           {"EST", "EDT"},    // America/New_York
 	"US Mountain Standard Time":       {"MST", "MST"},    // America/Phoenix
 	"Canada Central Standard Time":    {"CST", "CST"},    // America/Regina
-	"Pacific Standard Time (Mexico)":  {"PST", "PDT"},    // America/Santa_Isabel
 	"Pacific SA Standard Time":        {"CLT", "CLST"},   // America/Santiago
 	"E. South America Standard Time":  {"BRT", "BRST"},   // America/Sao_Paulo
 	"Newfoundland Standard Time":      {"NST", "NDT"},    // America/St_Johns
-	"Central Asia Standard Time":      {"ALMT", "ALMT"},  // Asia/Almaty
+	"Central Asia Standard Time":      {"+06", "+06"},    // Asia/Almaty
 	"Jordan Standard Time":            {"EET", "EEST"},   // Asia/Amman
 	"Arabic Standard Time":            {"AST", "AST"},    // Asia/Baghdad
-	"Azerbaijan Standard Time":        {"AZT", "AZST"},   // Asia/Baku
+	"Azerbaijan Standard Time":        {"AZT", "AZT"},    // Asia/Baku
 	"SE Asia Standard Time":           {"ICT", "ICT"},    // Asia/Bangkok
+	"Altai Standard Time":             {"+06", "+07"},    // Asia/Barnaul
 	"Middle East Standard Time":       {"EET", "EEST"},   // Asia/Beirut
 	"India Standard Time":             {"IST", "IST"},    // Asia/Calcutta
+	"Transbaikal Standard Time":       {"IRKT", "YAKT"},  // Asia/Chita
 	"Sri Lanka Standard Time":         {"IST", "IST"},    // Asia/Colombo
 	"Syria Standard Time":             {"EET", "EEST"},   // Asia/Damascus
 	"Bangladesh Standard Time":        {"BDT", "BDT"},    // Asia/Dhaka
@@ -60,22 +62,26 @@ var abbrs = map[string]abbr{
 	"North Asia East Standard Time":   {"IRKT", "IRKT"},  // Asia/Irkutsk
 	"Israel Standard Time":            {"IST", "IDT"},    // Asia/Jerusalem
 	"Afghanistan Standard Time":       {"AFT", "AFT"},    // Asia/Kabul
+	"Russia Time Zone 11":             {"PETT", "PETT"},  // Asia/Kamchatka
 	"Pakistan Standard Time":          {"PKT", "PKT"},    // Asia/Karachi
 	"Nepal Standard Time":             {"NPT", "NPT"},    // Asia/Katmandu
 	"North Asia Standard Time":        {"KRAT", "KRAT"},  // Asia/Krasnoyarsk
 	"Magadan Standard Time":           {"MAGT", "MAGT"},  // Asia/Magadan
 	"N. Central Asia Standard Time":   {"NOVT", "NOVT"},  // Asia/Novosibirsk
+	"North Korea Standard Time":       {"KST", "KST"},    // Asia/Pyongyang
 	"Myanmar Standard Time":           {"MMT", "MMT"},    // Asia/Rangoon
 	"Arab Standard Time":              {"AST", "AST"},    // Asia/Riyadh
+	"Sakhalin Standard Time":          {"SAKT", "SAKT"},  // Asia/Sakhalin
 	"Korea Standard Time":             {"KST", "KST"},    // Asia/Seoul
 	"China Standard Time":             {"CST", "CST"},    // Asia/Shanghai
 	"Singapore Standard Time":         {"SGT", "SGT"},    // Asia/Singapore
+	"Russia Time Zone 10":             {"SRET", "SRET"},  // Asia/Srednekolymsk
 	"Taipei Standard Time":            {"CST", "CST"},    // Asia/Taipei
 	"West Asia Standard Time":         {"UZT", "UZT"},    // Asia/Tashkent
 	"Georgian Standard Time":          {"GET", "GET"},    // Asia/Tbilisi
 	"Iran Standard Time":              {"IRST", "IRDT"},  // Asia/Tehran
 	"Tokyo Standard Time":             {"JST", "JST"},    // Asia/Tokyo
-	"Ulaanbaatar Standard Time":       {"ULAT", "ULAT"},  // Asia/Ulaanbaatar
+	"Ulaanbaatar Standard Time":       {"ULAT", "ULAST"}, // Asia/Ulaanbaatar
 	"Vladivostok Standard Time":       {"VLAT", "VLAT"},  // Asia/Vladivostok
 	"Yakutsk Standard Time":           {"YAKT", "YAKT"},  // Asia/Yakutsk
 	"Ekaterinburg Standard Time":      {"YEKT", "YEKT"},  // Asia/Yekaterinburg
@@ -83,31 +89,35 @@ var abbrs = map[string]abbr{
 	"Azores Standard Time":            {"AZOT", "AZOST"}, // Atlantic/Azores
 	"Cape Verde Standard Time":        {"CVT", "CVT"},    // Atlantic/Cape_Verde
 	"Greenwich Standard Time":         {"GMT", "GMT"},    // Atlantic/Reykjavik
-	"Cen. Australia Standard Time":    {"CST", "CST"},    // Australia/Adelaide
-	"E. Australia Standard Time":      {"EST", "EST"},    // Australia/Brisbane
-	"AUS Central Standard Time":       {"CST", "CST"},    // Australia/Darwin
-	"Tasmania Standard Time":          {"EST", "EST"},    // Australia/Hobart
-	"W. Australia Standard Time":      {"WST", "WST"},    // Australia/Perth
-	"AUS Eastern Standard Time":       {"EST", "EST"},    // Australia/Sydney
+	"Cen. Australia Standard Time":    {"ACST", "ACDT"},  // Australia/Adelaide
+	"E. Australia Standard Time":      {"AEST", "AEST"},  // Australia/Brisbane
+	"AUS Central Standard Time":       {"ACST", "ACST"},  // Australia/Darwin
+	"Tasmania Standard Time":          {"AEST", "AEDT"},  // Australia/Hobart
+	"W. Australia Standard Time":      {"AWST", "AWST"},  // Australia/Perth
+	"AUS Eastern Standard Time":       {"AEST", "AEDT"},  // Australia/Sydney
 	"UTC":                            {"GMT", "GMT"},       // Etc/GMT
 	"UTC-11":                         {"GMT+11", "GMT+11"}, // Etc/GMT+11
 	"Dateline Standard Time":         {"GMT+12", "GMT+12"}, // Etc/GMT+12
 	"UTC-02":                         {"GMT+2", "GMT+2"},   // Etc/GMT+2
 	"UTC+12":                         {"GMT-12", "GMT-12"}, // Etc/GMT-12
+	"Astrakhan Standard Time":        {"+03", "+04"},       // Europe/Astrakhan
 	"W. Europe Standard Time":        {"CET", "CEST"},      // Europe/Berlin
 	"GTB Standard Time":              {"EET", "EEST"},      // Europe/Bucharest
 	"Central Europe Standard Time":   {"CET", "CEST"},      // Europe/Budapest
+	"E. Europe Standard Time":        {"EET", "EEST"},      // Europe/Chisinau
 	"Turkey Standard Time":           {"EET", "EEST"},      // Europe/Istanbul
-	"Kaliningrad Standard Time":      {"FET", "FET"},       // Europe/Kaliningrad
+	"Kaliningrad Standard Time":      {"EET", "EET"},       // Europe/Kaliningrad
 	"FLE Standard Time":              {"EET", "EEST"},      // Europe/Kiev
 	"GMT Standard Time":              {"GMT", "BST"},       // Europe/London
+	"Belarus Standard Time":          {"MSK", "MSK"},       // Europe/Minsk
 	"Russian Standard Time":          {"MSK", "MSK"},       // Europe/Moscow
 	"Romance Standard Time":          {"CET", "CEST"},      // Europe/Paris
+	"Russia Time Zone 3":             {"SAMT", "SAMT"},     // Europe/Samara
 	"Central European Standard Time": {"CET", "CEST"},      // Europe/Warsaw
 	"Mauritius Standard Time":        {"MUT", "MUT"},       // Indian/Mauritius
-	"Samoa Standard Time":            {"WST", "WST"},       // Pacific/Apia
+	"Samoa Standard Time":            {"WSST", "WSDT"},     // Pacific/Apia
 	"New Zealand Standard Time":      {"NZST", "NZDT"},     // Pacific/Auckland
-	"Fiji Standard Time":             {"FJT", "FJT"},       // Pacific/Fiji
+	"Fiji Standard Time":             {"FJT", "FJST"},      // Pacific/Fiji
 	"Central Pacific Standard Time":  {"SBT", "SBT"},       // Pacific/Guadalcanal
 	"Hawaiian Standard Time":         {"HST", "HST"},       // Pacific/Honolulu
 	"Line Islands Standard Time":     {"LINT", "LINT"},     // Pacific/Kiritimati
diff --git a/libgo/go/time/zoneinfo_read.go b/libgo/go/time/zoneinfo_read.go
index de9ebb41c82..19cd40d8477 100644
--- a/libgo/go/time/zoneinfo_read.go
+++ b/libgo/go/time/zoneinfo_read.go
@@ -11,6 +11,13 @@ package time
 
 import "errors"
 
+// Copies of io.Seek* constants to avoid importing "io":
+const (
+	seekStart   = 0
+	seekCurrent = 1
+	seekEnd     = 2
+)
+
 // Simple I/O interface to binary blob of data.
 type data struct {
 	p     []byte
@@ -210,10 +217,10 @@ func loadZoneFile(dir, name string) (l *Location, err error) {
 	return loadZoneData(buf)
 }
 
-// There are 500+ zoneinfo files.  Rather than distribute them all
+// There are 500+ zoneinfo files. Rather than distribute them all
 // individually, we ship them in an uncompressed zip file.
 // Used this way, the zip file format serves as a commonly readable
-// container for the individual small files.  We choose zip over tar
+// container for the individual small files. We choose zip over tar
 // because zip files have a contiguous table of contents, making
 // individual file lookups faster, and because the per-file overhead
 // in a zip file is considerably less than tar's 512 bytes.
diff --git a/libgo/go/time/zoneinfo_test.go b/libgo/go/time/zoneinfo_test.go
index ede5330f5cc..5b6a4dc4e4e 100644
--- a/libgo/go/time/zoneinfo_test.go
+++ b/libgo/go/time/zoneinfo_test.go
@@ -20,7 +20,7 @@ func TestVersion3(t *testing.T) {
 }
 
 // Test that we get the correct results for times before the first
-// transition time.  To do this we explicitly check early dates in a
+// transition time. To do this we explicitly check early dates in a
 // couple of specific timezones.
 func TestFirstZone(t *testing.T) {
 	t.Skip("gccgo does not use the zip file")
@@ -64,3 +64,12 @@ func TestFirstZone(t *testing.T) {
 		}
 	}
 }
+
+func TestLocationNames(t *testing.T) {
+	if time.Local.String() != "Local" {
+		t.Errorf(`invalid Local location name: got %q want "Local"`, time.Local)
+	}
+	if time.UTC.String() != "UTC" {
+		t.Errorf(`invalid UTC location name: got %q want "UTC"`, time.UTC)
+	}
+}
diff --git a/libgo/go/time/zoneinfo_unix.go b/libgo/go/time/zoneinfo_unix.go
index 5fc669e478d..6c7aafff77b 100644
--- a/libgo/go/time/zoneinfo_unix.go
+++ b/libgo/go/time/zoneinfo_unix.go
@@ -18,8 +18,12 @@ import (
 )
 
 func initTestingZone() {
-	syscall.Setenv("TZ", "America/Los_Angeles")
-	initLocal()
+	z, err := loadLocation("America/Los_Angeles")
+	if err != nil {
+		panic("cannot load America/Los_Angeles for testing: " + err.Error())
+	}
+	z.name = "Local"
+	localLoc = *z
 }
 
 // Many systems use /usr/share/zoneinfo, Solaris 2 has
diff --git a/libgo/go/time/zoneinfo_windows.go b/libgo/go/time/zoneinfo_windows.go
index bcb8ccd5632..a6546f54b86 100644
--- a/libgo/go/time/zoneinfo_windows.go
+++ b/libgo/go/time/zoneinfo_windows.go
@@ -83,7 +83,7 @@ func extractCAPS(desc string) string {
 	var short []rune
 	for _, c := range desc {
 		if 'A' <= c && c <= 'Z' {
-			short = append(short, rune(c))
+			short = append(short, c)
 		}
 	}
 	return string(short)
@@ -140,6 +140,8 @@ func pseudoUnix(year int, d *syscall.Systemtime) int64 {
 func initLocalFromTZI(i *syscall.Timezoneinformation) {
 	l := &localLoc
 
+	l.name = "Local"
+
 	nzone := 1
 	if i.StandardDate.Month > 0 {
 		nzone++
diff --git a/libgo/go/unicode/graphic.go b/libgo/go/unicode/graphic.go
index 81eae3e7623..ca6241949a2 100644
--- a/libgo/go/unicode/graphic.go
+++ b/libgo/go/unicode/graphic.go
@@ -45,7 +45,7 @@ func IsGraphic(r rune) bool {
 // IsPrint reports whether the rune is defined as printable by Go. Such
 // characters include letters, marks, numbers, punctuation, symbols, and the
 // ASCII space character, from categories L, M, N, P, S and the ASCII space
-// character.  This categorization is the same as IsGraphic except that the
+// character. This categorization is the same as IsGraphic except that the
 // only spacing character is ASCII space, U+0020.
 func IsPrint(r rune) bool {
 	if uint32(r) <= MaxLatin1 {
diff --git a/libgo/go/unicode/letter.go b/libgo/go/unicode/letter.go
index 7fe4241eddf..8aec920d22f 100644
--- a/libgo/go/unicode/letter.go
+++ b/libgo/go/unicode/letter.go
@@ -27,7 +27,7 @@ type RangeTable struct {
 	LatinOffset int // number of entries in R16 with Hi <= MaxLatin1
 }
 
-// Range16 represents of a range of 16-bit Unicode code points.  The range runs from Lo to Hi
+// Range16 represents of a range of 16-bit Unicode code points. The range runs from Lo to Hi
 // inclusive and has the specified stride.
 type Range16 struct {
 	Lo     uint16
@@ -36,7 +36,7 @@ type Range16 struct {
 }
 
 // Range32 represents of a range of Unicode code points and is used when one or
-// more of the values will not fit in 16 bits.  The range runs from Lo to Hi
+// more of the values will not fit in 16 bits. The range runs from Lo to Hi
 // inclusive and has the specified stride. Lo and Hi must always be >= 1<<16.
 type Range32 struct {
 	Lo     uint32
@@ -48,10 +48,10 @@ type Range32 struct {
 // code point to one code point) case conversion.
 // The range runs from Lo to Hi inclusive, with a fixed stride of 1.  Deltas
 // are the number to add to the code point to reach the code point for a
-// different case for that character.  They may be negative.  If zero, it
+// different case for that character. They may be negative. If zero, it
 // means the character is in the corresponding case. There is a special
 // case representing sequences of alternating corresponding Upper and Lower
-// pairs.  It appears with a fixed Delta of
+// pairs. It appears with a fixed Delta of
 //	{UpperLower, UpperLower, UpperLower}
 // The constant UpperLower has an otherwise impossible delta value.
 type CaseRange struct {
@@ -217,7 +217,7 @@ func to(_case int, r rune, caseRange []CaseRange) rune {
 		m := lo + (hi-lo)/2
 		cr := caseRange[m]
 		if rune(cr.Lo) <= r && r <= rune(cr.Hi) {
-			delta := rune(cr.Delta[_case])
+			delta := cr.Delta[_case]
 			if delta > MaxRune {
 				// In an Upper-Lower sequence, which always starts with
 				// an UpperCase letter, the real deltas always look like:
@@ -307,7 +307,7 @@ func (special SpecialCase) ToLower(r rune) rune {
 	return r1
 }
 
-// caseOrbit is defined in tables.go as []foldPair.  Right now all the
+// caseOrbit is defined in tables.go as []foldPair. Right now all the
 // entries fit in uint16, so use uint16.  If that changes, compilation
 // will fail (the constants in the composite literal will not fit in uint16)
 // and the types here can change to uint32.
@@ -317,7 +317,7 @@ type foldPair struct {
 }
 
 // SimpleFold iterates over Unicode code points equivalent under
-// the Unicode-defined simple case folding.  Among the code points
+// the Unicode-defined simple case folding. Among the code points
 // equivalent to rune (including rune itself), SimpleFold returns the
 // smallest rune > r if one exists, or else the smallest rune >= 0.
 //
@@ -332,6 +332,10 @@ type foldPair struct {
 //	SimpleFold('1') = '1'
 //
 func SimpleFold(r rune) rune {
+	if int(r) < len(asciiFold) {
+		return rune(asciiFold[r])
+	}
+
 	// Consult caseOrbit table for special cases.
 	lo := 0
 	hi := len(caseOrbit)
@@ -347,7 +351,7 @@ func SimpleFold(r rune) rune {
 		return rune(caseOrbit[lo].To)
 	}
 
-	// No folding specified.  This is a one- or two-element
+	// No folding specified. This is a one- or two-element
 	// equivalence class containing rune and ToLower(rune)
 	// and ToUpper(rune) if they are different from rune.
 	if l := ToLower(r); l != r {
diff --git a/libgo/go/unicode/letter_test.go b/libgo/go/unicode/letter_test.go
index a40b412f66d..0eb9ee95b08 100644
--- a/libgo/go/unicode/letter_test.go
+++ b/libgo/go/unicode/letter_test.go
@@ -73,7 +73,6 @@ var letterTest = []rune{
 	0x1200,
 	0x1312,
 	0x1401,
-	0x1885,
 	0x2c00,
 	0xa800,
 	0xf900,
@@ -94,6 +93,7 @@ var notletterTest = []rune{
 	0x375,
 	0x619,
 	0x700,
+	0x1885,
 	0xfffe,
 	0x1ffff,
 	0x10ffff,
diff --git a/libgo/go/unicode/script_test.go b/libgo/go/unicode/script_test.go
index 935c225c376..1fe4581e6c2 100644
--- a/libgo/go/unicode/script_test.go
+++ b/libgo/go/unicode/script_test.go
@@ -18,10 +18,12 @@ type T struct {
 // mostly to discover when new scripts and categories arise.
 var inTest = []T{
 	{0x11711, "Ahom"},
+	{0x1e900, "Adlam"},
 	{0x14646, "Anatolian_Hieroglyphs"},
 	{0x06e2, "Arabic"},
 	{0x0567, "Armenian"},
 	{0x10b20, "Avestan"},
+	{0x11c00, "Bhaiksuki"},
 	{0x1b37, "Balinese"},
 	{0xa6af, "Bamum"},
 	{0x16ada, "Bassa_Vah"},
@@ -89,6 +91,7 @@ var inTest = []T{
 	{0x0d42, "Malayalam"},
 	{0x0843, "Mandaic"},
 	{0x10ac8, "Manichaean"},
+	{0x11cB6, "Marchen"},
 	{0xabd0, "Meetei_Mayek"},
 	{0x1e800, "Mende_Kikakui"},
 	{0x1099f, "Meroitic_Hieroglyphs"},
@@ -100,6 +103,7 @@ var inTest = []T{
 	{0x11293, "Multani"},
 	{0x104c, "Myanmar"},
 	{0x10880, "Nabataean"},
+	{0x11400, "Newa"},
 	{0x19c3, "New_Tai_Lue"},
 	{0x07f8, "Nko"},
 	{0x169b, "Ogham"},
@@ -112,6 +116,7 @@ var inTest = []T{
 	{0x10a6f, "Old_South_Arabian"},
 	{0x10c20, "Old_Turkic"},
 	{0x0b3e, "Oriya"},
+	{0x104d9, "Osage"},
 	{0x10491, "Osmanya"},
 	{0x16b2b, "Pahawh_Hmong"},
 	{0x10876, "Palmyrene"},
@@ -139,6 +144,7 @@ var inTest = []T{
 	{0xaadc, "Tai_Viet"},
 	{0x116c9, "Takri"},
 	{0x0bbf, "Tamil"},
+	{0x17000, "Tangut"},
 	{0x0c55, "Telugu"},
 	{0x07a7, "Thaana"},
 	{0x0e46, "Thai"},
@@ -220,9 +226,11 @@ var inPropTest = []T{
 	{0x216F, "Other_Uppercase"},
 	{0x0027, "Pattern_Syntax"},
 	{0x0020, "Pattern_White_Space"},
+	{0x06DD, "Prepended_Concatenation_Mark"},
 	{0x300D, "Quotation_Mark"},
 	{0x2EF3, "Radical"},
-	{0x061F, "STerm"},
+	{0x061F, "STerm"}, // Deprecated alias of Sentence_Terminal
+	{0x061F, "Sentence_Terminal"},
 	{0x2071, "Soft_Dotted"},
 	{0x003A, "Terminal_Punctuation"},
 	{0x9FC3, "Unified_Ideograph"},
diff --git a/libgo/go/unicode/tables.go b/libgo/go/unicode/tables.go
index 8bb42062f9e..15fecd954f1 100644
--- a/libgo/go/unicode/tables.go
+++ b/libgo/go/unicode/tables.go
@@ -3,13 +3,13 @@
 // license that can be found in the LICENSE file.
 
 // Generated by running
-//	maketables --tables=all --data=http://www.unicode.org/Public/8.0.0/ucd/UnicodeData.txt --casefolding=http://www.unicode.org/Public/8.0.0/ucd/CaseFolding.txt
+//	maketables --tables=all --data=http://www.unicode.org/Public/9.0.0/ucd/UnicodeData.txt --casefolding=http://www.unicode.org/Public/9.0.0/ucd/CaseFolding.txt
 // DO NOT EDIT
 
 package unicode
 
 // Version is the Unicode edition from which the tables are derived.
-const Version = "8.0.0"
+const Version = "9.0.0"
 
 // Categories is the set of Unicode category tables.
 var Categories = map[string]*RangeTable{
@@ -58,8 +58,9 @@ var _C = &RangeTable{
 		{0x00ad, 0x0600, 1363},
 		{0x0601, 0x0605, 1},
 		{0x061c, 0x06dd, 193},
-		{0x070f, 0x180e, 4351},
-		{0x200b, 0x200f, 1},
+		{0x070f, 0x08e2, 467},
+		{0x180e, 0x200b, 2045},
+		{0x200c, 0x200f, 1},
 		{0x202a, 0x202e, 1},
 		{0x2060, 0x2064, 1},
 		{0x2066, 0x206f, 1},
@@ -92,8 +93,9 @@ var _Cf = &RangeTable{
 		{0x00ad, 0x0600, 1363},
 		{0x0601, 0x0605, 1},
 		{0x061c, 0x06dd, 193},
-		{0x070f, 0x180e, 4351},
-		{0x200b, 0x200f, 1},
+		{0x070f, 0x08e2, 467},
+		{0x180e, 0x200b, 2045},
+		{0x200c, 0x200f, 1},
 		{0x202a, 0x202e, 1},
 		{0x2060, 0x2064, 1},
 		{0x2066, 0x206f, 1},
@@ -171,6 +173,7 @@ var _L = &RangeTable{
 		{0x0828, 0x0840, 24},
 		{0x0841, 0x0858, 1},
 		{0x08a0, 0x08b4, 1},
+		{0x08b6, 0x08bd, 1},
 		{0x0904, 0x0939, 1},
 		{0x093d, 0x0950, 19},
 		{0x0958, 0x0961, 1},
@@ -231,7 +234,8 @@ var _L = &RangeTable{
 		{0x0c3d, 0x0c58, 27},
 		{0x0c59, 0x0c5a, 1},
 		{0x0c60, 0x0c61, 1},
-		{0x0c85, 0x0c8c, 1},
+		{0x0c80, 0x0c85, 5},
+		{0x0c86, 0x0c8c, 1},
 		{0x0c8e, 0x0c90, 1},
 		{0x0c92, 0x0ca8, 1},
 		{0x0caa, 0x0cb3, 1},
@@ -242,8 +246,9 @@ var _L = &RangeTable{
 		{0x0d05, 0x0d0c, 1},
 		{0x0d0e, 0x0d10, 1},
 		{0x0d12, 0x0d3a, 1},
-		{0x0d3d, 0x0d5f, 17},
-		{0x0d60, 0x0d61, 1},
+		{0x0d3d, 0x0d4e, 17},
+		{0x0d54, 0x0d56, 1},
+		{0x0d5f, 0x0d61, 1},
 		{0x0d7a, 0x0d7f, 1},
 		{0x0d85, 0x0d96, 1},
 		{0x0d9a, 0x0db1, 1},
@@ -317,7 +322,8 @@ var _L = &RangeTable{
 		{0x1780, 0x17b3, 1},
 		{0x17d7, 0x17dc, 5},
 		{0x1820, 0x1877, 1},
-		{0x1880, 0x18a8, 1},
+		{0x1880, 0x1884, 1},
+		{0x1887, 0x18a8, 1},
 		{0x18aa, 0x18b0, 6},
 		{0x18b1, 0x18f5, 1},
 		{0x1900, 0x191e, 1},
@@ -336,6 +342,7 @@ var _L = &RangeTable{
 		{0x1c00, 0x1c23, 1},
 		{0x1c4d, 0x1c4f, 1},
 		{0x1c5a, 0x1c7d, 1},
+		{0x1c80, 0x1c88, 1},
 		{0x1ce9, 0x1cec, 1},
 		{0x1cee, 0x1cf1, 1},
 		{0x1cf5, 0x1cf6, 1},
@@ -412,7 +419,7 @@ var _L = &RangeTable{
 		{0xa6a0, 0xa6e5, 1},
 		{0xa717, 0xa71f, 1},
 		{0xa722, 0xa788, 1},
-		{0xa78b, 0xa7ad, 1},
+		{0xa78b, 0xa7ae, 1},
 		{0xa7b0, 0xa7b7, 1},
 		{0xa7f7, 0xa801, 1},
 		{0xa803, 0xa805, 1},
@@ -498,6 +505,8 @@ var _L = &RangeTable{
 		{0x103a0, 0x103c3, 1},
 		{0x103c8, 0x103cf, 1},
 		{0x10400, 0x1049d, 1},
+		{0x104b0, 0x104d3, 1},
+		{0x104d8, 0x104fb, 1},
 		{0x10500, 0x10527, 1},
 		{0x10530, 0x10563, 1},
 		{0x10600, 0x10736, 1},
@@ -557,6 +566,8 @@ var _L = &RangeTable{
 		{0x11335, 0x11339, 1},
 		{0x1133d, 0x11350, 19},
 		{0x1135d, 0x11361, 1},
+		{0x11400, 0x11434, 1},
+		{0x11447, 0x1144a, 1},
 		{0x11480, 0x114af, 1},
 		{0x114c4, 0x114c5, 1},
 		{0x114c7, 0x11580, 185},
@@ -569,6 +580,10 @@ var _L = &RangeTable{
 		{0x118a0, 0x118df, 1},
 		{0x118ff, 0x11ac0, 449},
 		{0x11ac1, 0x11af8, 1},
+		{0x11c00, 0x11c08, 1},
+		{0x11c0a, 0x11c2e, 1},
+		{0x11c40, 0x11c72, 50},
+		{0x11c73, 0x11c8f, 1},
 		{0x12000, 0x12399, 1},
 		{0x12480, 0x12543, 1},
 		{0x13000, 0x1342e, 1},
@@ -583,6 +598,9 @@ var _L = &RangeTable{
 		{0x16f00, 0x16f44, 1},
 		{0x16f50, 0x16f93, 67},
 		{0x16f94, 0x16f9f, 1},
+		{0x16fe0, 0x17000, 32},
+		{0x17001, 0x187ec, 1},
+		{0x18800, 0x18af2, 1},
 		{0x1b000, 0x1b001, 1},
 		{0x1bc00, 0x1bc6a, 1},
 		{0x1bc70, 0x1bc7c, 1},
@@ -619,6 +637,7 @@ var _L = &RangeTable{
 		{0x1d7aa, 0x1d7c2, 1},
 		{0x1d7c4, 0x1d7cb, 1},
 		{0x1e800, 0x1e8c4, 1},
+		{0x1e900, 0x1e943, 1},
 		{0x1ee00, 0x1ee03, 1},
 		{0x1ee05, 0x1ee1f, 1},
 		{0x1ee21, 0x1ee22, 1},
@@ -706,6 +725,7 @@ var _Ll = &RangeTable{
 		{0x04cf, 0x052f, 2},
 		{0x0561, 0x0587, 1},
 		{0x13f8, 0x13fd, 1},
+		{0x1c80, 0x1c88, 1},
 		{0x1d00, 0x1d2b, 1},
 		{0x1d6b, 0x1d77, 1},
 		{0x1d79, 0x1d9a, 1},
@@ -773,6 +793,7 @@ var _Ll = &RangeTable{
 	},
 	R32: []Range32{
 		{0x10428, 0x1044f, 1},
+		{0x104d8, 0x104fb, 1},
 		{0x10cc0, 0x10cf2, 1},
 		{0x118c0, 0x118df, 1},
 		{0x1d41a, 0x1d433, 1},
@@ -802,7 +823,8 @@ var _Ll = &RangeTable{
 		{0x1d78a, 0x1d78f, 1},
 		{0x1d7aa, 0x1d7c2, 1},
 		{0x1d7c4, 0x1d7c9, 1},
-		{0x1d7cb, 0x1d7cb, 1},
+		{0x1d7cb, 0x1e922, 4439},
+		{0x1e923, 0x1e943, 1},
 	},
 	LatinOffset: 4,
 }
@@ -854,6 +876,7 @@ var _Lm = &RangeTable{
 		{0x16b40, 0x16b40, 1},
 		{0x16b41, 0x16b43, 1},
 		{0x16f93, 0x16f9f, 1},
+		{0x16fe0, 0x16fe0, 1},
 	},
 }
 
@@ -880,6 +903,7 @@ var _Lo = &RangeTable{
 		{0x0800, 0x0815, 1},
 		{0x0840, 0x0858, 1},
 		{0x08a0, 0x08b4, 1},
+		{0x08b6, 0x08bd, 1},
 		{0x0904, 0x0939, 1},
 		{0x093d, 0x0950, 19},
 		{0x0958, 0x0961, 1},
@@ -940,7 +964,8 @@ var _Lo = &RangeTable{
 		{0x0c3d, 0x0c58, 27},
 		{0x0c59, 0x0c5a, 1},
 		{0x0c60, 0x0c61, 1},
-		{0x0c85, 0x0c8c, 1},
+		{0x0c80, 0x0c85, 5},
+		{0x0c86, 0x0c8c, 1},
 		{0x0c8e, 0x0c90, 1},
 		{0x0c92, 0x0ca8, 1},
 		{0x0caa, 0x0cb3, 1},
@@ -951,8 +976,9 @@ var _Lo = &RangeTable{
 		{0x0d05, 0x0d0c, 1},
 		{0x0d0e, 0x0d10, 1},
 		{0x0d12, 0x0d3a, 1},
-		{0x0d3d, 0x0d5f, 17},
-		{0x0d60, 0x0d61, 1},
+		{0x0d3d, 0x0d4e, 17},
+		{0x0d54, 0x0d56, 1},
+		{0x0d5f, 0x0d61, 1},
 		{0x0d7a, 0x0d7f, 1},
 		{0x0d85, 0x0d96, 1},
 		{0x0d9a, 0x0db1, 1},
@@ -1022,7 +1048,8 @@ var _Lo = &RangeTable{
 		{0x17dc, 0x1820, 68},
 		{0x1821, 0x1842, 1},
 		{0x1844, 0x1877, 1},
-		{0x1880, 0x18a8, 1},
+		{0x1880, 0x1884, 1},
+		{0x1887, 0x18a8, 1},
 		{0x18aa, 0x18b0, 6},
 		{0x18b1, 0x18f5, 1},
 		{0x1900, 0x191e, 1},
@@ -1211,6 +1238,8 @@ var _Lo = &RangeTable{
 		{0x11335, 0x11339, 1},
 		{0x1133d, 0x11350, 19},
 		{0x1135d, 0x11361, 1},
+		{0x11400, 0x11434, 1},
+		{0x11447, 0x1144a, 1},
 		{0x11480, 0x114af, 1},
 		{0x114c4, 0x114c5, 1},
 		{0x114c7, 0x11580, 185},
@@ -1222,6 +1251,10 @@ var _Lo = &RangeTable{
 		{0x11700, 0x11719, 1},
 		{0x118ff, 0x11ac0, 449},
 		{0x11ac1, 0x11af8, 1},
+		{0x11c00, 0x11c08, 1},
+		{0x11c0a, 0x11c2e, 1},
+		{0x11c40, 0x11c72, 50},
+		{0x11c73, 0x11c8f, 1},
 		{0x12000, 0x12399, 1},
 		{0x12480, 0x12543, 1},
 		{0x13000, 0x1342e, 1},
@@ -1233,9 +1266,11 @@ var _Lo = &RangeTable{
 		{0x16b63, 0x16b77, 1},
 		{0x16b7d, 0x16b8f, 1},
 		{0x16f00, 0x16f44, 1},
-		{0x16f50, 0x1b000, 16560},
-		{0x1b001, 0x1bc00, 3071},
-		{0x1bc01, 0x1bc6a, 1},
+		{0x16f50, 0x17000, 176},
+		{0x17001, 0x187ec, 1},
+		{0x18800, 0x18af2, 1},
+		{0x1b000, 0x1b001, 1},
+		{0x1bc00, 0x1bc6a, 1},
 		{0x1bc70, 0x1bc7c, 1},
 		{0x1bc80, 0x1bc88, 1},
 		{0x1bc90, 0x1bc99, 1},
@@ -1386,13 +1421,14 @@ var _Lu = &RangeTable{
 		{0xa78b, 0xa78d, 2},
 		{0xa790, 0xa792, 2},
 		{0xa796, 0xa7aa, 2},
-		{0xa7ab, 0xa7ad, 1},
+		{0xa7ab, 0xa7ae, 1},
 		{0xa7b0, 0xa7b4, 1},
 		{0xa7b6, 0xff21, 22379},
 		{0xff22, 0xff3a, 1},
 	},
 	R32: []Range32{
 		{0x10400, 0x10427, 1},
+		{0x104b0, 0x104d3, 1},
 		{0x10c80, 0x10cb2, 1},
 		{0x118a0, 0x118bf, 1},
 		{0x1d400, 0x1d419, 1},
@@ -1424,7 +1460,8 @@ var _Lu = &RangeTable{
 		{0x1d71c, 0x1d734, 1},
 		{0x1d756, 0x1d76e, 1},
 		{0x1d790, 0x1d7a8, 1},
-		{0x1d7ca, 0x1d7ca, 1},
+		{0x1d7ca, 0x1e900, 4406},
+		{0x1e901, 0x1e921, 1},
 	},
 	LatinOffset: 3,
 }
@@ -1453,6 +1490,7 @@ var _M = &RangeTable{
 		{0x0825, 0x0827, 1},
 		{0x0829, 0x082d, 1},
 		{0x0859, 0x085b, 1},
+		{0x08d4, 0x08e1, 1},
 		{0x08e3, 0x0903, 1},
 		{0x093a, 0x093c, 1},
 		{0x093e, 0x094f, 1},
@@ -1546,6 +1584,7 @@ var _M = &RangeTable{
 		{0x17b4, 0x17d3, 1},
 		{0x17dd, 0x180b, 46},
 		{0x180c, 0x180d, 1},
+		{0x1885, 0x1886, 1},
 		{0x18a9, 0x1920, 119},
 		{0x1921, 0x192b, 1},
 		{0x1930, 0x193b, 1},
@@ -1567,7 +1606,7 @@ var _M = &RangeTable{
 		{0x1cf3, 0x1cf4, 1},
 		{0x1cf8, 0x1cf9, 1},
 		{0x1dc0, 0x1df5, 1},
-		{0x1dfc, 0x1dff, 1},
+		{0x1dfb, 0x1dff, 1},
 		{0x20d0, 0x20f0, 1},
 		{0x2cef, 0x2cf1, 1},
 		{0x2d7f, 0x2de0, 97},
@@ -1582,7 +1621,7 @@ var _M = &RangeTable{
 		{0xa80b, 0xa823, 24},
 		{0xa824, 0xa827, 1},
 		{0xa880, 0xa881, 1},
-		{0xa8b4, 0xa8c4, 1},
+		{0xa8b4, 0xa8c5, 1},
 		{0xa8e0, 0xa8f1, 1},
 		{0xa926, 0xa92d, 1},
 		{0xa947, 0xa953, 1},
@@ -1626,7 +1665,8 @@ var _M = &RangeTable{
 		{0x111b3, 0x111c0, 1},
 		{0x111ca, 0x111cc, 1},
 		{0x1122c, 0x11237, 1},
-		{0x112df, 0x112ea, 1},
+		{0x1123e, 0x112df, 161},
+		{0x112e0, 0x112ea, 1},
 		{0x11300, 0x11303, 1},
 		{0x1133c, 0x1133e, 2},
 		{0x1133f, 0x11344, 1},
@@ -1636,6 +1676,7 @@ var _M = &RangeTable{
 		{0x11363, 0x11366, 3},
 		{0x11367, 0x1136c, 1},
 		{0x11370, 0x11374, 1},
+		{0x11435, 0x11446, 1},
 		{0x114b0, 0x114c3, 1},
 		{0x115af, 0x115b5, 1},
 		{0x115b8, 0x115c0, 1},
@@ -1643,6 +1684,10 @@ var _M = &RangeTable{
 		{0x11630, 0x11640, 1},
 		{0x116ab, 0x116b7, 1},
 		{0x1171d, 0x1172b, 1},
+		{0x11c2f, 0x11c36, 1},
+		{0x11c38, 0x11c3f, 1},
+		{0x11c92, 0x11ca7, 1},
+		{0x11ca9, 0x11cb6, 1},
 		{0x16af0, 0x16af4, 1},
 		{0x16b30, 0x16b36, 1},
 		{0x16f51, 0x16f7e, 1},
@@ -1659,7 +1704,13 @@ var _M = &RangeTable{
 		{0x1da75, 0x1da84, 15},
 		{0x1da9b, 0x1da9f, 1},
 		{0x1daa1, 0x1daaf, 1},
+		{0x1e000, 0x1e006, 1},
+		{0x1e008, 0x1e018, 1},
+		{0x1e01b, 0x1e021, 1},
+		{0x1e023, 0x1e024, 1},
+		{0x1e026, 0x1e02a, 1},
 		{0x1e8d0, 0x1e8d6, 1},
+		{0x1e944, 0x1e94a, 1},
 		{0xe0100, 0xe01ef, 1},
 	},
 }
@@ -1781,7 +1832,10 @@ var _Mc = &RangeTable{
 		{0x11347, 0x11348, 1},
 		{0x1134b, 0x1134d, 1},
 		{0x11357, 0x11362, 11},
-		{0x11363, 0x114b0, 333},
+		{0x11363, 0x11435, 210},
+		{0x11436, 0x11437, 1},
+		{0x11440, 0x11441, 1},
+		{0x11445, 0x114b0, 107},
 		{0x114b1, 0x114b2, 1},
 		{0x114b9, 0x114bb, 2},
 		{0x114bc, 0x114be, 1},
@@ -1795,7 +1849,10 @@ var _Mc = &RangeTable{
 		{0x116ae, 0x116af, 1},
 		{0x116b6, 0x11720, 106},
 		{0x11721, 0x11726, 5},
-		{0x16f51, 0x16f7e, 1},
+		{0x11c2f, 0x11c3e, 15},
+		{0x11ca9, 0x11cb1, 8},
+		{0x11cb4, 0x16f51, 21149},
+		{0x16f52, 0x16f7e, 1},
 		{0x1d165, 0x1d166, 1},
 		{0x1d16d, 0x1d172, 1},
 	},
@@ -1835,6 +1892,7 @@ var _Mn = &RangeTable{
 		{0x0825, 0x0827, 1},
 		{0x0829, 0x082d, 1},
 		{0x0859, 0x085b, 1},
+		{0x08d4, 0x08e1, 1},
 		{0x08e3, 0x0902, 1},
 		{0x093a, 0x093c, 2},
 		{0x0941, 0x0948, 1},
@@ -1913,6 +1971,7 @@ var _Mn = &RangeTable{
 		{0x17ca, 0x17d3, 1},
 		{0x17dd, 0x180b, 46},
 		{0x180c, 0x180d, 1},
+		{0x1885, 0x1886, 1},
 		{0x18a9, 0x1920, 119},
 		{0x1921, 0x1922, 1},
 		{0x1927, 0x1928, 1},
@@ -1946,7 +2005,7 @@ var _Mn = &RangeTable{
 		{0x1ced, 0x1cf4, 7},
 		{0x1cf8, 0x1cf9, 1},
 		{0x1dc0, 0x1df5, 1},
-		{0x1dfc, 0x1dff, 1},
+		{0x1dfb, 0x1dff, 1},
 		{0x20d0, 0x20dc, 1},
 		{0x20e1, 0x20e5, 4},
 		{0x20e6, 0x20f0, 1},
@@ -1962,7 +2021,8 @@ var _Mn = &RangeTable{
 		{0xa802, 0xa806, 4},
 		{0xa80b, 0xa825, 26},
 		{0xa826, 0xa8c4, 158},
-		{0xa8e0, 0xa8f1, 1},
+		{0xa8c5, 0xa8e0, 27},
+		{0xa8e1, 0xa8f1, 1},
 		{0xa926, 0xa92d, 1},
 		{0xa947, 0xa951, 1},
 		{0xa980, 0xa982, 1},
@@ -2006,13 +2066,17 @@ var _Mn = &RangeTable{
 		{0x111ca, 0x111cc, 1},
 		{0x1122f, 0x11231, 1},
 		{0x11234, 0x11236, 2},
-		{0x11237, 0x112df, 168},
-		{0x112e3, 0x112ea, 1},
+		{0x11237, 0x1123e, 7},
+		{0x112df, 0x112e3, 4},
+		{0x112e4, 0x112ea, 1},
 		{0x11300, 0x11301, 1},
 		{0x1133c, 0x11340, 4},
 		{0x11366, 0x1136c, 1},
 		{0x11370, 0x11374, 1},
-		{0x114b3, 0x114b8, 1},
+		{0x11438, 0x1143f, 1},
+		{0x11442, 0x11444, 1},
+		{0x11446, 0x114b3, 109},
+		{0x114b4, 0x114b8, 1},
 		{0x114ba, 0x114bf, 5},
 		{0x114c0, 0x114c2, 2},
 		{0x114c3, 0x115b2, 239},
@@ -2029,6 +2093,13 @@ var _Mn = &RangeTable{
 		{0x1171e, 0x1171f, 1},
 		{0x11722, 0x11725, 1},
 		{0x11727, 0x1172b, 1},
+		{0x11c30, 0x11c36, 1},
+		{0x11c38, 0x11c3d, 1},
+		{0x11c3f, 0x11c92, 83},
+		{0x11c93, 0x11ca7, 1},
+		{0x11caa, 0x11cb0, 1},
+		{0x11cb2, 0x11cb3, 1},
+		{0x11cb5, 0x11cb6, 1},
 		{0x16af0, 0x16af4, 1},
 		{0x16b30, 0x16b36, 1},
 		{0x16f8f, 0x16f92, 1},
@@ -2043,7 +2114,13 @@ var _Mn = &RangeTable{
 		{0x1da75, 0x1da84, 15},
 		{0x1da9b, 0x1da9f, 1},
 		{0x1daa1, 0x1daaf, 1},
+		{0x1e000, 0x1e006, 1},
+		{0x1e008, 0x1e018, 1},
+		{0x1e01b, 0x1e021, 1},
+		{0x1e023, 0x1e024, 1},
+		{0x1e026, 0x1e02a, 1},
 		{0x1e8d0, 0x1e8d6, 1},
+		{0x1e944, 0x1e94a, 1},
 		{0xe0100, 0xe01ef, 1},
 	},
 }
@@ -2068,7 +2145,8 @@ var _N = &RangeTable{
 		{0x0c66, 0x0c6f, 1},
 		{0x0c78, 0x0c7e, 1},
 		{0x0ce6, 0x0cef, 1},
-		{0x0d66, 0x0d75, 1},
+		{0x0d58, 0x0d5e, 1},
+		{0x0d66, 0x0d78, 1},
 		{0x0de6, 0x0def, 1},
 		{0x0e50, 0x0e59, 1},
 		{0x0ed0, 0x0ed9, 1},
@@ -2148,11 +2226,13 @@ var _N = &RangeTable{
 		{0x111d0, 0x111d9, 1},
 		{0x111e1, 0x111f4, 1},
 		{0x112f0, 0x112f9, 1},
+		{0x11450, 0x11459, 1},
 		{0x114d0, 0x114d9, 1},
 		{0x11650, 0x11659, 1},
 		{0x116c0, 0x116c9, 1},
 		{0x11730, 0x1173b, 1},
 		{0x118e0, 0x118f2, 1},
+		{0x11c50, 0x11c6c, 1},
 		{0x12400, 0x1246e, 1},
 		{0x16a60, 0x16a69, 1},
 		{0x16b50, 0x16b59, 1},
@@ -2160,6 +2240,7 @@ var _N = &RangeTable{
 		{0x1d360, 0x1d371, 1},
 		{0x1d7ce, 0x1d7ff, 1},
 		{0x1e8c7, 0x1e8cf, 1},
+		{0x1e950, 0x1e959, 1},
 		{0x1f100, 0x1f10c, 1},
 	},
 	LatinOffset: 4,
@@ -2212,14 +2293,17 @@ var _Nd = &RangeTable{
 		{0x11136, 0x1113f, 1},
 		{0x111d0, 0x111d9, 1},
 		{0x112f0, 0x112f9, 1},
+		{0x11450, 0x11459, 1},
 		{0x114d0, 0x114d9, 1},
 		{0x11650, 0x11659, 1},
 		{0x116c0, 0x116c9, 1},
 		{0x11730, 0x11739, 1},
 		{0x118e0, 0x118e9, 1},
+		{0x11c50, 0x11c59, 1},
 		{0x16a60, 0x16a69, 1},
 		{0x16b50, 0x16b59, 1},
 		{0x1d7ce, 0x1d7ff, 1},
+		{0x1e950, 0x1e959, 1},
 	},
 	LatinOffset: 1,
 }
@@ -2251,7 +2335,8 @@ var _No = &RangeTable{
 		{0x0b72, 0x0b77, 1},
 		{0x0bf0, 0x0bf2, 1},
 		{0x0c78, 0x0c7e, 1},
-		{0x0d70, 0x0d75, 1},
+		{0x0d58, 0x0d5e, 1},
+		{0x0d70, 0x0d78, 1},
 		{0x0f2a, 0x0f33, 1},
 		{0x1369, 0x137c, 1},
 		{0x17f0, 0x17f9, 1},
@@ -2299,6 +2384,7 @@ var _No = &RangeTable{
 		{0x111e1, 0x111f4, 1},
 		{0x1173a, 0x1173b, 1},
 		{0x118ea, 0x118f2, 1},
+		{0x11c5a, 0x11c6c, 1},
 		{0x16b5b, 0x16b61, 1},
 		{0x1d360, 0x1d371, 1},
 		{0x1e8c7, 0x1e8cf, 1},
@@ -2385,7 +2471,7 @@ var _P = &RangeTable{
 		{0x2cfe, 0x2cff, 1},
 		{0x2d70, 0x2e00, 144},
 		{0x2e01, 0x2e2e, 1},
-		{0x2e30, 0x2e42, 1},
+		{0x2e30, 0x2e44, 1},
 		{0x3001, 0x3003, 1},
 		{0x3008, 0x3011, 1},
 		{0x3014, 0x301f, 1},
@@ -2441,16 +2527,23 @@ var _P = &RangeTable{
 		{0x111cd, 0x111db, 14},
 		{0x111dd, 0x111df, 1},
 		{0x11238, 0x1123d, 1},
-		{0x112a9, 0x114c6, 541},
-		{0x115c1, 0x115d7, 1},
+		{0x112a9, 0x1144b, 418},
+		{0x1144c, 0x1144f, 1},
+		{0x1145b, 0x1145d, 2},
+		{0x114c6, 0x115c1, 251},
+		{0x115c2, 0x115d7, 1},
 		{0x11641, 0x11643, 1},
+		{0x11660, 0x1166c, 1},
 		{0x1173c, 0x1173e, 1},
+		{0x11c41, 0x11c45, 1},
+		{0x11c70, 0x11c71, 1},
 		{0x12470, 0x12474, 1},
 		{0x16a6e, 0x16a6f, 1},
 		{0x16af5, 0x16b37, 66},
 		{0x16b38, 0x16b3b, 1},
 		{0x16b44, 0x1bc9f, 20827},
 		{0x1da87, 0x1da8b, 1},
+		{0x1e95e, 0x1e95f, 1},
 	},
 	LatinOffset: 11,
 }
@@ -2605,7 +2698,8 @@ var _Po = &RangeTable{
 		{0x2e2b, 0x2e2e, 1},
 		{0x2e30, 0x2e39, 1},
 		{0x2e3c, 0x2e3f, 1},
-		{0x2e41, 0x3001, 448},
+		{0x2e41, 0x2e43, 2},
+		{0x2e44, 0x3001, 445},
 		{0x3002, 0x3003, 1},
 		{0x303d, 0x30fb, 190},
 		{0xa4fe, 0xa4ff, 1},
@@ -2661,16 +2755,23 @@ var _Po = &RangeTable{
 		{0x111cd, 0x111db, 14},
 		{0x111dd, 0x111df, 1},
 		{0x11238, 0x1123d, 1},
-		{0x112a9, 0x114c6, 541},
-		{0x115c1, 0x115d7, 1},
+		{0x112a9, 0x1144b, 418},
+		{0x1144c, 0x1144f, 1},
+		{0x1145b, 0x1145d, 2},
+		{0x114c6, 0x115c1, 251},
+		{0x115c2, 0x115d7, 1},
 		{0x11641, 0x11643, 1},
+		{0x11660, 0x1166c, 1},
 		{0x1173c, 0x1173e, 1},
+		{0x11c41, 0x11c45, 1},
+		{0x11c70, 0x11c71, 1},
 		{0x12470, 0x12474, 1},
 		{0x16a6e, 0x16a6f, 1},
 		{0x16af5, 0x16b37, 66},
 		{0x16b38, 0x16b3b, 1},
 		{0x16b44, 0x1bc9f, 20827},
 		{0x1da87, 0x1da8b, 1},
+		{0x1e95e, 0x1e95f, 1},
 	},
 	LatinOffset: 8,
 }
@@ -2736,9 +2837,9 @@ var _S = &RangeTable{
 		{0x09fa, 0x09fb, 1},
 		{0x0af1, 0x0b70, 127},
 		{0x0bf3, 0x0bfa, 1},
-		{0x0c7f, 0x0d79, 250},
-		{0x0e3f, 0x0f01, 194},
-		{0x0f02, 0x0f03, 1},
+		{0x0c7f, 0x0d4f, 208},
+		{0x0d79, 0x0e3f, 198},
+		{0x0f01, 0x0f03, 1},
 		{0x0f13, 0x0f15, 2},
 		{0x0f16, 0x0f17, 1},
 		{0x0f1a, 0x0f1f, 1},
@@ -2778,7 +2879,7 @@ var _S = &RangeTable{
 		{0x218b, 0x2190, 5},
 		{0x2191, 0x2307, 1},
 		{0x230c, 0x2328, 1},
-		{0x232b, 0x23fa, 1},
+		{0x232b, 0x23fe, 1},
 		{0x2400, 0x2426, 1},
 		{0x2440, 0x244a, 1},
 		{0x249c, 0x24e9, 1},
@@ -2839,8 +2940,8 @@ var _S = &RangeTable{
 	R32: []Range32{
 		{0x10137, 0x1013f, 1},
 		{0x10179, 0x10189, 1},
-		{0x1018c, 0x10190, 4},
-		{0x10191, 0x1019b, 1},
+		{0x1018c, 0x1018e, 1},
+		{0x10190, 0x1019b, 1},
 		{0x101a0, 0x101d0, 48},
 		{0x101d1, 0x101fc, 1},
 		{0x10877, 0x10878, 1},
@@ -2876,16 +2977,14 @@ var _S = &RangeTable{
 		{0x1f0d1, 0x1f0f5, 1},
 		{0x1f110, 0x1f12e, 1},
 		{0x1f130, 0x1f16b, 1},
-		{0x1f170, 0x1f19a, 1},
+		{0x1f170, 0x1f1ac, 1},
 		{0x1f1e6, 0x1f202, 1},
-		{0x1f210, 0x1f23a, 1},
+		{0x1f210, 0x1f23b, 1},
 		{0x1f240, 0x1f248, 1},
 		{0x1f250, 0x1f251, 1},
-		{0x1f300, 0x1f579, 1},
-		{0x1f57b, 0x1f5a3, 1},
-		{0x1f5a5, 0x1f6d0, 1},
+		{0x1f300, 0x1f6d2, 1},
 		{0x1f6e0, 0x1f6ec, 1},
-		{0x1f6f0, 0x1f6f3, 1},
+		{0x1f6f0, 0x1f6f6, 1},
 		{0x1f700, 0x1f773, 1},
 		{0x1f780, 0x1f7d4, 1},
 		{0x1f800, 0x1f80b, 1},
@@ -2893,8 +2992,13 @@ var _S = &RangeTable{
 		{0x1f850, 0x1f859, 1},
 		{0x1f860, 0x1f887, 1},
 		{0x1f890, 0x1f8ad, 1},
-		{0x1f910, 0x1f918, 1},
-		{0x1f980, 0x1f984, 1},
+		{0x1f910, 0x1f91e, 1},
+		{0x1f920, 0x1f927, 1},
+		{0x1f930, 0x1f933, 3},
+		{0x1f934, 0x1f93e, 1},
+		{0x1f940, 0x1f94b, 1},
+		{0x1f950, 0x1f95e, 1},
+		{0x1f980, 0x1f991, 1},
 		{0x1f9c0, 0x1f9c0, 1},
 	},
 	LatinOffset: 10,
@@ -3020,8 +3124,8 @@ var _So = &RangeTable{
 		{0x09fa, 0x0b70, 374},
 		{0x0bf3, 0x0bf8, 1},
 		{0x0bfa, 0x0c7f, 133},
-		{0x0d79, 0x0f01, 392},
-		{0x0f02, 0x0f03, 1},
+		{0x0d4f, 0x0d79, 42},
+		{0x0f01, 0x0f03, 1},
 		{0x0f13, 0x0f15, 2},
 		{0x0f16, 0x0f17, 1},
 		{0x0f1a, 0x0f1f, 1},
@@ -3063,7 +3167,7 @@ var _So = &RangeTable{
 		{0x232b, 0x237b, 1},
 		{0x237d, 0x239a, 1},
 		{0x23b4, 0x23db, 1},
-		{0x23e2, 0x23fa, 1},
+		{0x23e2, 0x23fe, 1},
 		{0x2400, 0x2426, 1},
 		{0x2440, 0x244a, 1},
 		{0x249c, 0x24e9, 1},
@@ -3116,8 +3220,8 @@ var _So = &RangeTable{
 		{0x10137, 0x10137, 1},
 		{0x10138, 0x1013f, 1},
 		{0x10179, 0x10189, 1},
-		{0x1018c, 0x10190, 4},
-		{0x10191, 0x1019b, 1},
+		{0x1018c, 0x1018e, 1},
+		{0x10190, 0x1019b, 1},
 		{0x101a0, 0x101d0, 48},
 		{0x101d1, 0x101fc, 1},
 		{0x10877, 0x10878, 1},
@@ -3147,17 +3251,15 @@ var _So = &RangeTable{
 		{0x1f0d1, 0x1f0f5, 1},
 		{0x1f110, 0x1f12e, 1},
 		{0x1f130, 0x1f16b, 1},
-		{0x1f170, 0x1f19a, 1},
+		{0x1f170, 0x1f1ac, 1},
 		{0x1f1e6, 0x1f202, 1},
-		{0x1f210, 0x1f23a, 1},
+		{0x1f210, 0x1f23b, 1},
 		{0x1f240, 0x1f248, 1},
 		{0x1f250, 0x1f251, 1},
 		{0x1f300, 0x1f3fa, 1},
-		{0x1f400, 0x1f579, 1},
-		{0x1f57b, 0x1f5a3, 1},
-		{0x1f5a5, 0x1f6d0, 1},
+		{0x1f400, 0x1f6d2, 1},
 		{0x1f6e0, 0x1f6ec, 1},
-		{0x1f6f0, 0x1f6f3, 1},
+		{0x1f6f0, 0x1f6f6, 1},
 		{0x1f700, 0x1f773, 1},
 		{0x1f780, 0x1f7d4, 1},
 		{0x1f800, 0x1f80b, 1},
@@ -3165,8 +3267,13 @@ var _So = &RangeTable{
 		{0x1f850, 0x1f859, 1},
 		{0x1f860, 0x1f887, 1},
 		{0x1f890, 0x1f8ad, 1},
-		{0x1f910, 0x1f918, 1},
-		{0x1f980, 0x1f984, 1},
+		{0x1f910, 0x1f91e, 1},
+		{0x1f920, 0x1f927, 1},
+		{0x1f930, 0x1f933, 3},
+		{0x1f934, 0x1f93e, 1},
+		{0x1f940, 0x1f94b, 1},
+		{0x1f950, 0x1f95e, 1},
+		{0x1f980, 0x1f991, 1},
 		{0x1f9c0, 0x1f9c0, 1},
 	},
 	LatinOffset: 2,
@@ -3259,11 +3366,12 @@ var (
 )
 
 // Generated by running
-//	maketables --scripts=all --url=http://www.unicode.org/Public/8.0.0/ucd/
+//	maketables --scripts=all --url=http://www.unicode.org/Public/9.0.0/ucd/
 // DO NOT EDIT
 
 // Scripts is the set of Unicode script tables.
 var Scripts = map[string]*RangeTable{
+	"Adlam":                  Adlam,
 	"Ahom":                   Ahom,
 	"Anatolian_Hieroglyphs":  Anatolian_Hieroglyphs,
 	"Arabic":                 Arabic,
@@ -3274,6 +3382,7 @@ var Scripts = map[string]*RangeTable{
 	"Bassa_Vah":              Bassa_Vah,
 	"Batak":                  Batak,
 	"Bengali":                Bengali,
+	"Bhaiksuki":              Bhaiksuki,
 	"Bopomofo":               Bopomofo,
 	"Brahmi":                 Brahmi,
 	"Braille":                Braille,
@@ -3335,6 +3444,7 @@ var Scripts = map[string]*RangeTable{
 	"Malayalam":              Malayalam,
 	"Mandaic":                Mandaic,
 	"Manichaean":             Manichaean,
+	"Marchen":                Marchen,
 	"Meetei_Mayek":           Meetei_Mayek,
 	"Mende_Kikakui":          Mende_Kikakui,
 	"Meroitic_Cursive":       Meroitic_Cursive,
@@ -3347,6 +3457,7 @@ var Scripts = map[string]*RangeTable{
 	"Myanmar":                Myanmar,
 	"Nabataean":              Nabataean,
 	"New_Tai_Lue":            New_Tai_Lue,
+	"Newa":                   Newa,
 	"Nko":                    Nko,
 	"Ogham":                  Ogham,
 	"Ol_Chiki":               Ol_Chiki,
@@ -3358,6 +3469,7 @@ var Scripts = map[string]*RangeTable{
 	"Old_South_Arabian":      Old_South_Arabian,
 	"Old_Turkic":             Old_Turkic,
 	"Oriya":                  Oriya,
+	"Osage":                  Osage,
 	"Osmanya":                Osmanya,
 	"Pahawh_Hmong":           Pahawh_Hmong,
 	"Palmyrene":              Palmyrene,
@@ -3385,6 +3497,7 @@ var Scripts = map[string]*RangeTable{
 	"Tai_Viet":               Tai_Viet,
 	"Takri":                  Takri,
 	"Tamil":                  Tamil,
+	"Tangut":                 Tangut,
 	"Telugu":                 Telugu,
 	"Thaana":                 Thaana,
 	"Thai":                   Thai,
@@ -3397,6 +3510,15 @@ var Scripts = map[string]*RangeTable{
 	"Yi":                     Yi,
 }
 
+var _Adlam = &RangeTable{
+	R16: []Range16{},
+	R32: []Range32{
+		{0x1e900, 0x1e94a, 1},
+		{0x1e950, 0x1e959, 1},
+		{0x1e95e, 0x1e95f, 1},
+	},
+}
+
 var _Ahom = &RangeTable{
 	R16: []Range16{},
 	R32: []Range32{
@@ -3426,6 +3548,8 @@ var _Arabic = &RangeTable{
 		{0x06de, 0x06ff, 1},
 		{0x0750, 0x077f, 1},
 		{0x08a0, 0x08b4, 1},
+		{0x08b6, 0x08bd, 1},
+		{0x08d4, 0x08e1, 1},
 		{0x08e3, 0x08ff, 1},
 		{0xfb50, 0xfbc1, 1},
 		{0xfbd3, 0xfd3d, 1},
@@ -3543,6 +3667,16 @@ var _Bengali = &RangeTable{
 	},
 }
 
+var _Bhaiksuki = &RangeTable{
+	R16: []Range16{},
+	R32: []Range32{
+		{0x11c00, 0x11c08, 1},
+		{0x11c0a, 0x11c36, 1},
+		{0x11c38, 0x11c45, 1},
+		{0x11c50, 0x11c6c, 1},
+	},
+}
+
 var _Bopomofo = &RangeTable{
 	R16: []Range16{
 		{0x02ea, 0x02eb, 1},
@@ -3649,6 +3783,7 @@ var _Common = &RangeTable{
 		{0x061f, 0x061f, 1},
 		{0x0640, 0x0640, 1},
 		{0x06dd, 0x06dd, 1},
+		{0x08e2, 0x08e2, 1},
 		{0x0964, 0x0965, 1},
 		{0x0e3f, 0x0e3f, 1},
 		{0x0fd5, 0x0fd8, 1},
@@ -3674,7 +3809,7 @@ var _Common = &RangeTable{
 		{0x2133, 0x214d, 1},
 		{0x214f, 0x215f, 1},
 		{0x2189, 0x218b, 1},
-		{0x2190, 0x23fa, 1},
+		{0x2190, 0x23fe, 1},
 		{0x2400, 0x2426, 1},
 		{0x2440, 0x244a, 1},
 		{0x2460, 0x27ff, 1},
@@ -3684,7 +3819,7 @@ var _Common = &RangeTable{
 		{0x2bbd, 0x2bc8, 1},
 		{0x2bca, 0x2bd1, 1},
 		{0x2bec, 0x2bef, 1},
-		{0x2e00, 0x2e42, 1},
+		{0x2e00, 0x2e44, 1},
 		{0x2ff0, 0x2ffb, 1},
 		{0x3000, 0x3004, 1},
 		{0x3006, 0x3006, 1},
@@ -3768,17 +3903,15 @@ var _Common = &RangeTable{
 		{0x1f100, 0x1f10c, 1},
 		{0x1f110, 0x1f12e, 1},
 		{0x1f130, 0x1f16b, 1},
-		{0x1f170, 0x1f19a, 1},
+		{0x1f170, 0x1f1ac, 1},
 		{0x1f1e6, 0x1f1ff, 1},
 		{0x1f201, 0x1f202, 1},
-		{0x1f210, 0x1f23a, 1},
+		{0x1f210, 0x1f23b, 1},
 		{0x1f240, 0x1f248, 1},
 		{0x1f250, 0x1f251, 1},
-		{0x1f300, 0x1f579, 1},
-		{0x1f57b, 0x1f5a3, 1},
-		{0x1f5a5, 0x1f6d0, 1},
+		{0x1f300, 0x1f6d2, 1},
 		{0x1f6e0, 0x1f6ec, 1},
-		{0x1f6f0, 0x1f6f3, 1},
+		{0x1f6f0, 0x1f6f6, 1},
 		{0x1f700, 0x1f773, 1},
 		{0x1f780, 0x1f7d4, 1},
 		{0x1f800, 0x1f80b, 1},
@@ -3786,8 +3919,13 @@ var _Common = &RangeTable{
 		{0x1f850, 0x1f859, 1},
 		{0x1f860, 0x1f887, 1},
 		{0x1f890, 0x1f8ad, 1},
-		{0x1f910, 0x1f918, 1},
-		{0x1f980, 0x1f984, 1},
+		{0x1f910, 0x1f91e, 1},
+		{0x1f920, 0x1f927, 1},
+		{0x1f930, 0x1f930, 1},
+		{0x1f933, 0x1f93e, 1},
+		{0x1f940, 0x1f94b, 1},
+		{0x1f950, 0x1f95e, 1},
+		{0x1f980, 0x1f991, 1},
 		{0x1f9c0, 0x1f9c0, 1},
 		{0xe0001, 0xe0001, 1},
 		{0xe0020, 0xe007f, 1},
@@ -3829,6 +3967,7 @@ var _Cyrillic = &RangeTable{
 	R16: []Range16{
 		{0x0400, 0x0484, 1},
 		{0x0487, 0x052f, 1},
+		{0x1c80, 0x1c88, 1},
 		{0x1d2b, 0x1d2b, 1},
 		{0x1d78, 0x1d78, 1},
 		{0x2de0, 0x2dff, 1},
@@ -3933,6 +4072,13 @@ var _Glagolitic = &RangeTable{
 		{0x2c00, 0x2c2e, 1},
 		{0x2c30, 0x2c5e, 1},
 	},
+	R32: []Range32{
+		{0x1e000, 0x1e006, 1},
+		{0x1e008, 0x1e018, 1},
+		{0x1e01b, 0x1e021, 1},
+		{0x1e023, 0x1e024, 1},
+		{0x1e026, 0x1e02a, 1},
+	},
 }
 
 var _Gothic = &RangeTable{
@@ -4000,7 +4146,7 @@ var _Greek = &RangeTable{
 		{0xab65, 0xab65, 1},
 	},
 	R32: []Range32{
-		{0x10140, 0x1018c, 1},
+		{0x10140, 0x1018e, 1},
 		{0x101a0, 0x101a0, 1},
 		{0x1d200, 0x1d245, 1},
 	},
@@ -4151,7 +4297,7 @@ var _Inherited = &RangeTable{
 		{0x1cf4, 0x1cf4, 1},
 		{0x1cf8, 0x1cf9, 1},
 		{0x1dc0, 0x1df5, 1},
-		{0x1dfc, 0x1dff, 1},
+		{0x1dfb, 0x1dff, 1},
 		{0x200c, 0x200d, 1},
 		{0x20d0, 0x20f0, 1},
 		{0x302a, 0x302d, 1},
@@ -4203,7 +4349,7 @@ var _Kaithi = &RangeTable{
 
 var _Kannada = &RangeTable{
 	R16: []Range16{
-		{0x0c81, 0x0c83, 1},
+		{0x0c80, 0x0c83, 1},
 		{0x0c85, 0x0c8c, 1},
 		{0x0c8e, 0x0c90, 1},
 		{0x0c92, 0x0ca8, 1},
@@ -4269,7 +4415,7 @@ var _Khojki = &RangeTable{
 	R16: []Range16{},
 	R32: []Range32{
 		{0x11200, 0x11211, 1},
-		{0x11213, 0x1123d, 1},
+		{0x11213, 0x1123e, 1},
 	},
 }
 
@@ -4329,7 +4475,7 @@ var _Latin = &RangeTable{
 		{0x2160, 0x2188, 1},
 		{0x2c60, 0x2c7f, 1},
 		{0xa722, 0xa787, 1},
-		{0xa78b, 0xa7ad, 1},
+		{0xa78b, 0xa7ae, 1},
 		{0xa7b0, 0xa7b7, 1},
 		{0xa7f7, 0xa7ff, 1},
 		{0xab30, 0xab5a, 1},
@@ -4417,11 +4563,9 @@ var _Malayalam = &RangeTable{
 		{0x0d12, 0x0d3a, 1},
 		{0x0d3d, 0x0d44, 1},
 		{0x0d46, 0x0d48, 1},
-		{0x0d4a, 0x0d4e, 1},
-		{0x0d57, 0x0d57, 1},
-		{0x0d5f, 0x0d63, 1},
-		{0x0d66, 0x0d75, 1},
-		{0x0d79, 0x0d7f, 1},
+		{0x0d4a, 0x0d4f, 1},
+		{0x0d54, 0x0d63, 1},
+		{0x0d66, 0x0d7f, 1},
 	},
 }
 
@@ -4440,6 +4584,15 @@ var _Manichaean = &RangeTable{
 	},
 }
 
+var _Marchen = &RangeTable{
+	R16: []Range16{},
+	R32: []Range32{
+		{0x11c70, 0x11c8f, 1},
+		{0x11c92, 0x11ca7, 1},
+		{0x11ca9, 0x11cb6, 1},
+	},
+}
+
 var _Meetei_Mayek = &RangeTable{
 	R16: []Range16{
 		{0xaae0, 0xaaf6, 1},
@@ -4498,6 +4651,9 @@ var _Mongolian = &RangeTable{
 		{0x1820, 0x1877, 1},
 		{0x1880, 0x18aa, 1},
 	},
+	R32: []Range32{
+		{0x11660, 0x1166c, 1},
+	},
 }
 
 var _Mro = &RangeTable{
@@ -4545,6 +4701,15 @@ var _New_Tai_Lue = &RangeTable{
 	},
 }
 
+var _Newa = &RangeTable{
+	R16: []Range16{},
+	R32: []Range32{
+		{0x11400, 0x11459, 1},
+		{0x1145b, 0x1145b, 1},
+		{0x1145d, 0x1145d, 1},
+	},
+}
+
 var _Nko = &RangeTable{
 	R16: []Range16{
 		{0x07c0, 0x07fa, 1},
@@ -4634,6 +4799,14 @@ var _Oriya = &RangeTable{
 	},
 }
 
+var _Osage = &RangeTable{
+	R16: []Range16{},
+	R32: []Range32{
+		{0x104b0, 0x104d3, 1},
+		{0x104d8, 0x104fb, 1},
+	},
+}
+
 var _Osmanya = &RangeTable{
 	R16: []Range16{},
 	R32: []Range32{
@@ -4713,7 +4886,7 @@ var _Samaritan = &RangeTable{
 
 var _Saurashtra = &RangeTable{
 	R16: []Range16{
-		{0xa880, 0xa8c4, 1},
+		{0xa880, 0xa8c5, 1},
 		{0xa8ce, 0xa8d9, 1},
 	},
 }
@@ -4867,6 +5040,15 @@ var _Tamil = &RangeTable{
 	},
 }
 
+var _Tangut = &RangeTable{
+	R16: []Range16{},
+	R32: []Range32{
+		{0x16fe0, 0x16fe0, 1},
+		{0x17000, 0x187ec, 1},
+		{0x18800, 0x18af2, 1},
+	},
+}
+
 var _Telugu = &RangeTable{
 	R16: []Range16{
 		{0x0c00, 0x0c03, 1},
@@ -4957,6 +5139,7 @@ var _Yi = &RangeTable{
 
 // These variables have type *RangeTable.
 var (
+	Adlam                  = _Adlam                  // Adlam is the set of Unicode characters in script Adlam.
 	Ahom                   = _Ahom                   // Ahom is the set of Unicode characters in script Ahom.
 	Anatolian_Hieroglyphs  = _Anatolian_Hieroglyphs  // Anatolian_Hieroglyphs is the set of Unicode characters in script Anatolian_Hieroglyphs.
 	Arabic                 = _Arabic                 // Arabic is the set of Unicode characters in script Arabic.
@@ -4967,6 +5150,7 @@ var (
 	Bassa_Vah              = _Bassa_Vah              // Bassa_Vah is the set of Unicode characters in script Bassa_Vah.
 	Batak                  = _Batak                  // Batak is the set of Unicode characters in script Batak.
 	Bengali                = _Bengali                // Bengali is the set of Unicode characters in script Bengali.
+	Bhaiksuki              = _Bhaiksuki              // Bhaiksuki is the set of Unicode characters in script Bhaiksuki.
 	Bopomofo               = _Bopomofo               // Bopomofo is the set of Unicode characters in script Bopomofo.
 	Brahmi                 = _Brahmi                 // Brahmi is the set of Unicode characters in script Brahmi.
 	Braille                = _Braille                // Braille is the set of Unicode characters in script Braille.
@@ -5028,6 +5212,7 @@ var (
 	Malayalam              = _Malayalam              // Malayalam is the set of Unicode characters in script Malayalam.
 	Mandaic                = _Mandaic                // Mandaic is the set of Unicode characters in script Mandaic.
 	Manichaean             = _Manichaean             // Manichaean is the set of Unicode characters in script Manichaean.
+	Marchen                = _Marchen                // Marchen is the set of Unicode characters in script Marchen.
 	Meetei_Mayek           = _Meetei_Mayek           // Meetei_Mayek is the set of Unicode characters in script Meetei_Mayek.
 	Mende_Kikakui          = _Mende_Kikakui          // Mende_Kikakui is the set of Unicode characters in script Mende_Kikakui.
 	Meroitic_Cursive       = _Meroitic_Cursive       // Meroitic_Cursive is the set of Unicode characters in script Meroitic_Cursive.
@@ -5040,6 +5225,7 @@ var (
 	Myanmar                = _Myanmar                // Myanmar is the set of Unicode characters in script Myanmar.
 	Nabataean              = _Nabataean              // Nabataean is the set of Unicode characters in script Nabataean.
 	New_Tai_Lue            = _New_Tai_Lue            // New_Tai_Lue is the set of Unicode characters in script New_Tai_Lue.
+	Newa                   = _Newa                   // Newa is the set of Unicode characters in script Newa.
 	Nko                    = _Nko                    // Nko is the set of Unicode characters in script Nko.
 	Ogham                  = _Ogham                  // Ogham is the set of Unicode characters in script Ogham.
 	Ol_Chiki               = _Ol_Chiki               // Ol_Chiki is the set of Unicode characters in script Ol_Chiki.
@@ -5051,6 +5237,7 @@ var (
 	Old_South_Arabian      = _Old_South_Arabian      // Old_South_Arabian is the set of Unicode characters in script Old_South_Arabian.
 	Old_Turkic             = _Old_Turkic             // Old_Turkic is the set of Unicode characters in script Old_Turkic.
 	Oriya                  = _Oriya                  // Oriya is the set of Unicode characters in script Oriya.
+	Osage                  = _Osage                  // Osage is the set of Unicode characters in script Osage.
 	Osmanya                = _Osmanya                // Osmanya is the set of Unicode characters in script Osmanya.
 	Pahawh_Hmong           = _Pahawh_Hmong           // Pahawh_Hmong is the set of Unicode characters in script Pahawh_Hmong.
 	Palmyrene              = _Palmyrene              // Palmyrene is the set of Unicode characters in script Palmyrene.
@@ -5078,6 +5265,7 @@ var (
 	Tai_Viet               = _Tai_Viet               // Tai_Viet is the set of Unicode characters in script Tai_Viet.
 	Takri                  = _Takri                  // Takri is the set of Unicode characters in script Takri.
 	Tamil                  = _Tamil                  // Tamil is the set of Unicode characters in script Tamil.
+	Tangut                 = _Tangut                 // Tangut is the set of Unicode characters in script Tangut.
 	Telugu                 = _Telugu                 // Telugu is the set of Unicode characters in script Telugu.
 	Thaana                 = _Thaana                 // Thaana is the set of Unicode characters in script Thaana.
 	Thai                   = _Thai                   // Thai is the set of Unicode characters in script Thai.
@@ -5091,7 +5279,7 @@ var (
 )
 
 // Generated by running
-//	maketables --props=all --url=http://www.unicode.org/Public/8.0.0/ucd/
+//	maketables --props=all --url=http://www.unicode.org/Public/9.0.0/ucd/
 // DO NOT EDIT
 
 // Properties is the set of Unicode property tables.
@@ -5120,9 +5308,11 @@ var Properties = map[string]*RangeTable{
 	"Other_Uppercase":                    Other_Uppercase,
 	"Pattern_Syntax":                     Pattern_Syntax,
 	"Pattern_White_Space":                Pattern_White_Space,
+	"Prepended_Concatenation_Mark":       Prepended_Concatenation_Mark,
 	"Quotation_Mark":                     Quotation_Mark,
 	"Radical":                            Radical,
-	"STerm":                              STerm,
+	"Sentence_Terminal":                  Sentence_Terminal,
+	"STerm":                              Sentence_Terminal,
 	"Soft_Dotted":                        Soft_Dotted,
 	"Terminal_Punctuation":               Terminal_Punctuation,
 	"Unified_Ideograph":                  Unified_Ideograph,
@@ -5187,7 +5377,6 @@ var _Deprecated = &RangeTable{
 	},
 	R32: []Range32{
 		{0xe0001, 0xe0001, 1},
-		{0xe007f, 0xe007f, 1},
 	},
 }
 
@@ -5329,11 +5518,14 @@ var _Diacritic = &RangeTable{
 		{0x1134d, 0x1134d, 1},
 		{0x11366, 0x1136c, 1},
 		{0x11370, 0x11374, 1},
+		{0x11442, 0x11442, 1},
+		{0x11446, 0x11446, 1},
 		{0x114c2, 0x114c3, 1},
 		{0x115bf, 0x115c0, 1},
 		{0x1163f, 0x1163f, 1},
 		{0x116b6, 0x116b7, 1},
 		{0x1172b, 0x1172b, 1},
+		{0x11c3f, 0x11c3f, 1},
 		{0x16af0, 0x16af4, 1},
 		{0x16f8f, 0x16f9f, 1},
 		{0x1d167, 0x1d169, 1},
@@ -5342,6 +5534,8 @@ var _Diacritic = &RangeTable{
 		{0x1d185, 0x1d18b, 1},
 		{0x1d1aa, 0x1d1ad, 1},
 		{0x1e8d0, 0x1e8d6, 1},
+		{0x1e944, 0x1e946, 1},
+		{0x1e948, 0x1e94a, 1},
 	},
 	LatinOffset: 6,
 }
@@ -5376,6 +5570,8 @@ var _Extender = &RangeTable{
 		{0x1135d, 0x1135d, 1},
 		{0x115c6, 0x115c8, 1},
 		{0x16b42, 0x16b43, 1},
+		{0x16fe0, 0x16fe0, 1},
+		{0x1e944, 0x1e946, 1},
 	},
 	LatinOffset: 1,
 }
@@ -5432,6 +5628,8 @@ var _Ideographic = &RangeTable{
 		{0xfa70, 0xfad9, 1},
 	},
 	R32: []Range32{
+		{0x17000, 0x187ec, 1},
+		{0x18800, 0x18af2, 1},
 		{0x20000, 0x2a6d6, 1},
 		{0x2a700, 0x2b734, 1},
 		{0x2b740, 0x2b81d, 1},
@@ -5506,6 +5704,7 @@ var _Other_Alphabetic = &RangeTable{
 		{0x081b, 0x0823, 1},
 		{0x0825, 0x0827, 1},
 		{0x0829, 0x082c, 1},
+		{0x08d4, 0x08df, 1},
 		{0x08e3, 0x08e9, 1},
 		{0x08f0, 0x0903, 1},
 		{0x093a, 0x093b, 1},
@@ -5591,6 +5790,7 @@ var _Other_Alphabetic = &RangeTable{
 		{0x1752, 0x1753, 1},
 		{0x1772, 0x1773, 1},
 		{0x17b6, 0x17c8, 1},
+		{0x1885, 0x1886, 1},
 		{0x18a9, 0x18a9, 1},
 		{0x1920, 0x192b, 1},
 		{0x1930, 0x1938, 1},
@@ -5613,6 +5813,7 @@ var _Other_Alphabetic = &RangeTable{
 		{0xa823, 0xa827, 1},
 		{0xa880, 0xa881, 1},
 		{0xa8b4, 0xa8c3, 1},
+		{0xa8c5, 0xa8c5, 1},
 		{0xa926, 0xa92a, 1},
 		{0xa947, 0xa952, 1},
 		{0xa980, 0xa983, 1},
@@ -5644,6 +5845,7 @@ var _Other_Alphabetic = &RangeTable{
 		{0x111b3, 0x111bf, 1},
 		{0x1122c, 0x11234, 1},
 		{0x11237, 0x11237, 1},
+		{0x1123e, 0x1123e, 1},
 		{0x112df, 0x112e8, 1},
 		{0x11300, 0x11303, 1},
 		{0x1133e, 0x11344, 1},
@@ -5651,6 +5853,8 @@ var _Other_Alphabetic = &RangeTable{
 		{0x1134b, 0x1134c, 1},
 		{0x11357, 0x11357, 1},
 		{0x11362, 0x11363, 1},
+		{0x11435, 0x11441, 1},
+		{0x11443, 0x11445, 1},
 		{0x114b0, 0x114c1, 1},
 		{0x115af, 0x115b5, 1},
 		{0x115b8, 0x115be, 1},
@@ -5659,9 +5863,19 @@ var _Other_Alphabetic = &RangeTable{
 		{0x11640, 0x11640, 1},
 		{0x116ab, 0x116b5, 1},
 		{0x1171d, 0x1172a, 1},
+		{0x11c2f, 0x11c36, 1},
+		{0x11c38, 0x11c3e, 1},
+		{0x11c92, 0x11ca7, 1},
+		{0x11ca9, 0x11cb6, 1},
 		{0x16b30, 0x16b36, 1},
 		{0x16f51, 0x16f7e, 1},
 		{0x1bc9e, 0x1bc9e, 1},
+		{0x1e000, 0x1e006, 1},
+		{0x1e008, 0x1e018, 1},
+		{0x1e01b, 0x1e021, 1},
+		{0x1e023, 0x1e024, 1},
+		{0x1e026, 0x1e02a, 1},
+		{0x1e947, 0x1e947, 1},
 		{0x1f130, 0x1f149, 1},
 		{0x1f150, 0x1f169, 1},
 		{0x1f170, 0x1f189, 1},
@@ -5700,7 +5914,7 @@ var _Other_Grapheme_Extend = &RangeTable{
 		{0x0d57, 0x0d57, 1},
 		{0x0dcf, 0x0dcf, 1},
 		{0x0ddf, 0x0ddf, 1},
-		{0x200c, 0x200d, 1},
+		{0x200c, 0x200c, 1},
 		{0x302e, 0x302f, 1},
 		{0xff9e, 0xff9f, 1},
 	},
@@ -5712,6 +5926,7 @@ var _Other_Grapheme_Extend = &RangeTable{
 		{0x115af, 0x115af, 1},
 		{0x1d165, 0x1d165, 1},
 		{0x1d16e, 0x1d172, 1},
+		{0xe0020, 0xe007f, 1},
 	},
 }
 
@@ -5727,6 +5942,7 @@ var _Other_ID_Continue = &RangeTable{
 
 var _Other_ID_Start = &RangeTable{
 	R16: []Range16{
+		{0x1885, 0x1886, 1},
 		{0x2118, 0x2118, 1},
 		{0x212e, 0x212e, 1},
 		{0x309b, 0x309c, 1},
@@ -5958,6 +6174,18 @@ var _Pattern_White_Space = &RangeTable{
 	LatinOffset: 3,
 }
 
+var _Prepended_Concatenation_Mark = &RangeTable{
+	R16: []Range16{
+		{0x0600, 0x0605, 1},
+		{0x06dd, 0x06dd, 1},
+		{0x070f, 0x070f, 1},
+		{0x08e2, 0x08e2, 1},
+	},
+	R32: []Range32{
+		{0x110bd, 0x110bd, 1},
+	},
+}
+
 var _Quotation_Mark = &RangeTable{
 	R16: []Range16{
 		{0x0022, 0x0022, 1},
@@ -5985,7 +6213,7 @@ var _Radical = &RangeTable{
 	},
 }
 
-var _STerm = &RangeTable{
+var _Sentence_Terminal = &RangeTable{
 	R16: []Range16{
 		{0x0021, 0x0021, 1},
 		{0x002e, 0x002e, 1},
@@ -6043,10 +6271,12 @@ var _STerm = &RangeTable{
 		{0x11238, 0x11239, 1},
 		{0x1123b, 0x1123c, 1},
 		{0x112a9, 0x112a9, 1},
+		{0x1144b, 0x1144c, 1},
 		{0x115c2, 0x115c3, 1},
 		{0x115c9, 0x115d7, 1},
 		{0x11641, 0x11642, 1},
 		{0x1173c, 0x1173e, 1},
+		{0x11c41, 0x11c42, 1},
 		{0x16a6e, 0x16a6f, 1},
 		{0x16af5, 0x16af5, 1},
 		{0x16b37, 0x16b38, 1},
@@ -6179,10 +6409,14 @@ var _Terminal_Punctuation = &RangeTable{
 		{0x111de, 0x111df, 1},
 		{0x11238, 0x1123c, 1},
 		{0x112a9, 0x112a9, 1},
+		{0x1144b, 0x1144d, 1},
+		{0x1145b, 0x1145b, 1},
 		{0x115c2, 0x115c5, 1},
 		{0x115c9, 0x115d7, 1},
 		{0x11641, 0x11642, 1},
 		{0x1173c, 0x1173e, 1},
+		{0x11c41, 0x11c43, 1},
+		{0x11c71, 0x11c71, 1},
 		{0x12470, 0x12474, 1},
 		{0x16a6e, 0x16a6f, 1},
 		{0x16af5, 0x16af5, 1},
@@ -6266,9 +6500,11 @@ var (
 	Other_Uppercase                    = _Other_Uppercase                    // Other_Uppercase is the set of Unicode characters with property Other_Uppercase.
 	Pattern_Syntax                     = _Pattern_Syntax                     // Pattern_Syntax is the set of Unicode characters with property Pattern_Syntax.
 	Pattern_White_Space                = _Pattern_White_Space                // Pattern_White_Space is the set of Unicode characters with property Pattern_White_Space.
+	Prepended_Concatenation_Mark       = _Prepended_Concatenation_Mark       // Prepended_Concatenation_Mark is the set of Unicode characters with property Prepended_Concatenation_Mark.
 	Quotation_Mark                     = _Quotation_Mark                     // Quotation_Mark is the set of Unicode characters with property Quotation_Mark.
 	Radical                            = _Radical                            // Radical is the set of Unicode characters with property Radical.
-	STerm                              = _STerm                              // STerm is the set of Unicode characters with property STerm.
+	STerm                              = _Sentence_Terminal                  // STerm is an alias for Sentence_Terminal.
+	Sentence_Terminal                  = _Sentence_Terminal                  // Sentence_Terminal is the set of Unicode characters with property Sentence_Terminal.
 	Soft_Dotted                        = _Soft_Dotted                        // Soft_Dotted is the set of Unicode characters with property Soft_Dotted.
 	Terminal_Punctuation               = _Terminal_Punctuation               // Terminal_Punctuation is the set of Unicode characters with property Terminal_Punctuation.
 	Unified_Ideograph                  = _Unified_Ideograph                  // Unified_Ideograph is the set of Unicode characters with property Unified_Ideograph.
@@ -6277,7 +6513,7 @@ var (
 )
 
 // Generated by running
-//	maketables --data=http://www.unicode.org/Public/8.0.0/ucd/UnicodeData.txt --casefolding=http://www.unicode.org/Public/8.0.0/ucd/CaseFolding.txt
+//	maketables --data=http://www.unicode.org/Public/9.0.0/ucd/UnicodeData.txt --casefolding=http://www.unicode.org/Public/9.0.0/ucd/CaseFolding.txt
 // DO NOT EDIT
 
 // CaseRanges is the table describing case mappings for all letters with
@@ -6383,6 +6619,7 @@ var _CaseRanges = []CaseRange{
 	{0x0266, 0x0266, d{42308, 0, 42308}},
 	{0x0268, 0x0268, d{-209, 0, -209}},
 	{0x0269, 0x0269, d{-211, 0, -211}},
+	{0x026A, 0x026A, d{42308, 0, 42308}},
 	{0x026B, 0x026B, d{10743, 0, 10743}},
 	{0x026C, 0x026C, d{42305, 0, 42305}},
 	{0x026F, 0x026F, d{-211, 0, -211}},
@@ -6453,6 +6690,14 @@ var _CaseRanges = []CaseRange{
 	{0x13A0, 0x13EF, d{0, 38864, 0}},
 	{0x13F0, 0x13F5, d{0, 8, 0}},
 	{0x13F8, 0x13FD, d{-8, 0, -8}},
+	{0x1C80, 0x1C80, d{-6254, 0, -6254}},
+	{0x1C81, 0x1C81, d{-6253, 0, -6253}},
+	{0x1C82, 0x1C82, d{-6244, 0, -6244}},
+	{0x1C83, 0x1C84, d{-6242, 0, -6242}},
+	{0x1C85, 0x1C85, d{-6243, 0, -6243}},
+	{0x1C86, 0x1C86, d{-6236, 0, -6236}},
+	{0x1C87, 0x1C87, d{-6181, 0, -6181}},
+	{0x1C88, 0x1C88, d{35266, 0, 35266}},
 	{0x1D79, 0x1D79, d{35332, 0, 35332}},
 	{0x1D7D, 0x1D7D, d{3814, 0, 3814}},
 	{0x1E00, 0x1E95, d{UpperLower, UpperLower, UpperLower}},
@@ -6559,6 +6804,7 @@ var _CaseRanges = []CaseRange{
 	{0xA7AB, 0xA7AB, d{0, -42319, 0}},
 	{0xA7AC, 0xA7AC, d{0, -42315, 0}},
 	{0xA7AD, 0xA7AD, d{0, -42305, 0}},
+	{0xA7AE, 0xA7AE, d{0, -42308, 0}},
 	{0xA7B0, 0xA7B0, d{0, -42258, 0}},
 	{0xA7B1, 0xA7B1, d{0, -42282, 0}},
 	{0xA7B2, 0xA7B2, d{0, -42261, 0}},
@@ -6570,10 +6816,14 @@ var _CaseRanges = []CaseRange{
 	{0xFF41, 0xFF5A, d{-32, 0, -32}},
 	{0x10400, 0x10427, d{0, 40, 0}},
 	{0x10428, 0x1044F, d{-40, 0, -40}},
+	{0x104B0, 0x104D3, d{0, 40, 0}},
+	{0x104D8, 0x104FB, d{-40, 0, -40}},
 	{0x10C80, 0x10CB2, d{0, 64, 0}},
 	{0x10CC0, 0x10CF2, d{-64, 0, -64}},
 	{0x118A0, 0x118BF, d{0, 32, 0}},
 	{0x118C0, 0x118DF, d{-32, 0, -32}},
+	{0x1E900, 0x1E921, d{0, 34, 0}},
+	{0x1E922, 0x1E943, d{-34, 0, -34}},
 }
 var properties = [MaxLatin1 + 1]uint8{
 	0x00: pC,       // '\x00'
@@ -6834,6 +7084,137 @@ var properties = [MaxLatin1 + 1]uint8{
 	0xFF: pLl | pp, // 'ÿ'
 }
 
+var asciiFold = [MaxASCII + 1]uint16{
+	0x0000,
+	0x0001,
+	0x0002,
+	0x0003,
+	0x0004,
+	0x0005,
+	0x0006,
+	0x0007,
+	0x0008,
+	0x0009,
+	0x000A,
+	0x000B,
+	0x000C,
+	0x000D,
+	0x000E,
+	0x000F,
+	0x0010,
+	0x0011,
+	0x0012,
+	0x0013,
+	0x0014,
+	0x0015,
+	0x0016,
+	0x0017,
+	0x0018,
+	0x0019,
+	0x001A,
+	0x001B,
+	0x001C,
+	0x001D,
+	0x001E,
+	0x001F,
+	0x0020,
+	0x0021,
+	0x0022,
+	0x0023,
+	0x0024,
+	0x0025,
+	0x0026,
+	0x0027,
+	0x0028,
+	0x0029,
+	0x002A,
+	0x002B,
+	0x002C,
+	0x002D,
+	0x002E,
+	0x002F,
+	0x0030,
+	0x0031,
+	0x0032,
+	0x0033,
+	0x0034,
+	0x0035,
+	0x0036,
+	0x0037,
+	0x0038,
+	0x0039,
+	0x003A,
+	0x003B,
+	0x003C,
+	0x003D,
+	0x003E,
+	0x003F,
+	0x0040,
+	0x0061,
+	0x0062,
+	0x0063,
+	0x0064,
+	0x0065,
+	0x0066,
+	0x0067,
+	0x0068,
+	0x0069,
+	0x006A,
+	0x006B,
+	0x006C,
+	0x006D,
+	0x006E,
+	0x006F,
+	0x0070,
+	0x0071,
+	0x0072,
+	0x0073,
+	0x0074,
+	0x0075,
+	0x0076,
+	0x0077,
+	0x0078,
+	0x0079,
+	0x007A,
+	0x005B,
+	0x005C,
+	0x005D,
+	0x005E,
+	0x005F,
+	0x0060,
+	0x0041,
+	0x0042,
+	0x0043,
+	0x0044,
+	0x0045,
+	0x0046,
+	0x0047,
+	0x0048,
+	0x0049,
+	0x004A,
+	0x212A,
+	0x004C,
+	0x004D,
+	0x004E,
+	0x004F,
+	0x0050,
+	0x0051,
+	0x0052,
+	0x017F,
+	0x0054,
+	0x0055,
+	0x0056,
+	0x0057,
+	0x0058,
+	0x0059,
+	0x005A,
+	0x007B,
+	0x007C,
+	0x007D,
+	0x007E,
+	0x007F,
+}
+
 var caseOrbit = []foldPair{
 	{0x004B, 0x006B},
 	{0x0053, 0x0073},
@@ -6890,6 +7271,29 @@ var caseOrbit = []foldPair{
 	{0x03F1, 0x03A1},
 	{0x03F4, 0x0398},
 	{0x03F5, 0x0395},
+	{0x0412, 0x0432},
+	{0x0414, 0x0434},
+	{0x041E, 0x043E},
+	{0x0421, 0x0441},
+	{0x0422, 0x0442},
+	{0x042A, 0x044A},
+	{0x0432, 0x1C80},
+	{0x0434, 0x1C81},
+	{0x043E, 0x1C82},
+	{0x0441, 0x1C83},
+	{0x0442, 0x1C84},
+	{0x044A, 0x1C86},
+	{0x0462, 0x0463},
+	{0x0463, 0x1C87},
+	{0x1C80, 0x0412},
+	{0x1C81, 0x0414},
+	{0x1C82, 0x041E},
+	{0x1C83, 0x0421},
+	{0x1C84, 0x1C85},
+	{0x1C85, 0x0422},
+	{0x1C86, 0x042A},
+	{0x1C87, 0x0462},
+	{0x1C88, 0xA64A},
 	{0x1E60, 0x1E61},
 	{0x1E61, 0x1E9B},
 	{0x1E9B, 0x1E60},
@@ -6898,6 +7302,8 @@ var caseOrbit = []foldPair{
 	{0x2126, 0x03A9},
 	{0x212A, 0x004B},
 	{0x212B, 0x00C5},
+	{0xA64A, 0xA64B},
+	{0xA64B, 0x1C88},
 }
 
 // FoldCategory maps a category name to a table of
@@ -7041,15 +7447,17 @@ var foldLl = &RangeTable{
 		{0xa78b, 0xa78d, 2},
 		{0xa790, 0xa792, 2},
 		{0xa796, 0xa7aa, 2},
-		{0xa7ab, 0xa7ad, 1},
+		{0xa7ab, 0xa7ae, 1},
 		{0xa7b0, 0xa7b4, 1},
 		{0xa7b6, 0xff21, 22379},
 		{0xff22, 0xff3a, 1},
 	},
 	R32: []Range32{
 		{0x10400, 0x10427, 1},
+		{0x104b0, 0x104d3, 1},
 		{0x10c80, 0x10cb2, 1},
 		{0x118a0, 0x118bf, 1},
+		{0x1e900, 0x1e921, 1},
 	},
 	LatinOffset: 3,
 }
@@ -7108,11 +7516,10 @@ var foldLu = &RangeTable{
 		{0x025c, 0x0260, 4},
 		{0x0261, 0x0265, 2},
 		{0x0266, 0x0268, 2},
-		{0x0269, 0x026b, 2},
-		{0x026c, 0x026f, 3},
-		{0x0271, 0x0272, 1},
-		{0x0275, 0x027d, 8},
-		{0x0280, 0x0283, 3},
+		{0x0269, 0x026c, 1},
+		{0x026f, 0x0271, 2},
+		{0x0272, 0x0275, 3},
+		{0x027d, 0x0283, 3},
 		{0x0287, 0x028c, 1},
 		{0x0292, 0x029d, 11},
 		{0x029e, 0x0345, 167},
@@ -7133,6 +7540,7 @@ var foldLu = &RangeTable{
 		{0x04cf, 0x052f, 2},
 		{0x0561, 0x0586, 1},
 		{0x13f8, 0x13fd, 1},
+		{0x1c80, 0x1c88, 1},
 		{0x1d79, 0x1d7d, 4},
 		{0x1e01, 0x1e95, 2},
 		{0x1e9b, 0x1ea1, 6},
@@ -7175,8 +7583,10 @@ var foldLu = &RangeTable{
 	},
 	R32: []Range32{
 		{0x10428, 0x1044f, 1},
+		{0x104d8, 0x104fb, 1},
 		{0x10cc0, 0x10cf2, 1},
 		{0x118c0, 0x118df, 1},
+		{0x1e922, 0x1e943, 1},
 	},
 	LatinOffset: 4,
 }
@@ -7201,7 +7611,7 @@ var foldMn = &RangeTable{
 // If there is no entry for a script name, there are no such points.
 var FoldScript = map[string]*RangeTable{}
 
-// Range entries: 3546 16-bit, 1306 32-bit, 4852 total.
-// Range bytes: 21276 16-bit, 15672 32-bit, 36948 total.
+// Range entries: 3576 16-bit, 1454 32-bit, 5030 total.
+// Range bytes: 21456 16-bit, 17448 32-bit, 38904 total.
 
-// Fold orbit bytes: 63 pairs, 252 bytes
+// Fold orbit bytes: 88 pairs, 352 bytes
diff --git a/libgo/go/unicode/utf16/export_test.go b/libgo/go/unicode/utf16/export_test.go
index 306247e48f1..e0c57f52aef 100644
--- a/libgo/go/unicode/utf16/export_test.go
+++ b/libgo/go/unicode/utf16/export_test.go
@@ -1,4 +1,4 @@
-// Copyright 2012 The Go Authors.  All rights reserved.
+// Copyright 2012 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
diff --git a/libgo/go/unicode/utf16/utf16.go b/libgo/go/unicode/utf16/utf16.go
index b497500778e..1a881aa7695 100644
--- a/libgo/go/unicode/utf16/utf16.go
+++ b/libgo/go/unicode/utf16/utf16.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -36,7 +36,7 @@ func IsSurrogate(r rune) bool {
 // the Unicode replacement code point U+FFFD.
 func DecodeRune(r1, r2 rune) rune {
 	if surr1 <= r1 && r1 < surr2 && surr2 <= r2 && r2 < surr3 {
-		return (r1-surr1)<<10 | (r2 - surr2) + 0x10000
+		return (r1-surr1)<<10 | (r2 - surr2) + surrSelf
 	}
 	return replacementChar
 }
@@ -45,7 +45,7 @@ func DecodeRune(r1, r2 rune) rune {
 // If the rune is not a valid Unicode code point or does not need encoding,
 // EncodeRune returns U+FFFD, U+FFFD.
 func EncodeRune(r rune) (r1, r2 rune) {
-	if r < surrSelf || r > maxRune || IsSurrogate(r) {
+	if r < surrSelf || r > maxRune {
 		return replacementChar, replacementChar
 	}
 	r -= surrSelf
@@ -65,20 +65,22 @@ func Encode(s []rune) []uint16 {
 	n = 0
 	for _, v := range s {
 		switch {
-		case v < 0, surr1 <= v && v < surr3, v > maxRune:
-			v = replacementChar
-			fallthrough
-		case v < surrSelf:
+		case 0 <= v && v < surr1, surr3 <= v && v < surrSelf:
+			// normal rune
 			a[n] = uint16(v)
 			n++
-		default:
+		case surrSelf <= v && v <= maxRune:
+			// needs surrogate sequence
 			r1, r2 := EncodeRune(v)
 			a[n] = uint16(r1)
 			a[n+1] = uint16(r2)
 			n += 2
+		default:
+			a[n] = uint16(replacementChar)
+			n++
 		}
 	}
-	return a[0:n]
+	return a[:n]
 }
 
 // Decode returns the Unicode code point sequence represented
@@ -88,21 +90,19 @@ func Decode(s []uint16) []rune {
 	n := 0
 	for i := 0; i < len(s); i++ {
 		switch r := s[i]; {
+		case r < surr1, surr3 <= r:
+			// normal rune
+			a[n] = rune(r)
 		case surr1 <= r && r < surr2 && i+1 < len(s) &&
 			surr2 <= s[i+1] && s[i+1] < surr3:
 			// valid surrogate sequence
 			a[n] = DecodeRune(rune(r), rune(s[i+1]))
 			i++
-			n++
-		case surr1 <= r && r < surr3:
+		default:
 			// invalid surrogate sequence
 			a[n] = replacementChar
-			n++
-		default:
-			// normal rune
-			a[n] = rune(r)
-			n++
 		}
+		n++
 	}
-	return a[0:n]
+	return a[:n]
 }
diff --git a/libgo/go/unicode/utf16/utf16_test.go b/libgo/go/unicode/utf16/utf16_test.go
index 3dca472bbe2..d258f0bc7b1 100644
--- a/libgo/go/unicode/utf16/utf16_test.go
+++ b/libgo/go/unicode/utf16/utf16_test.go
@@ -1,4 +1,4 @@
-// Copyright 2010 The Go Authors.  All rights reserved.
+// Copyright 2010 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -147,3 +147,56 @@ func TestIsSurrogate(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkDecodeValidASCII(b *testing.B) {
+	// "hello world"
+	data := []uint16{104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100}
+	for i := 0; i < b.N; i++ {
+		Decode(data)
+	}
+}
+
+func BenchmarkDecodeValidJapaneseChars(b *testing.B) {
+	// "日本語日本語日本語"
+	data := []uint16{26085, 26412, 35486, 26085, 26412, 35486, 26085, 26412, 35486}
+	for i := 0; i < b.N; i++ {
+		Decode(data)
+	}
+}
+
+func BenchmarkDecodeRune(b *testing.B) {
+	rs := make([]rune, 10)
+	// U+1D4D0 to U+1D4D4: MATHEMATICAL BOLD SCRIPT CAPITAL LETTERS
+	for i, u := range []rune{'𝓐', '𝓑', '𝓒', '𝓓', '𝓔'} {
+		rs[2*i], rs[2*i+1] = EncodeRune(u)
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		for j := 0; j < 5; j++ {
+			DecodeRune(rs[2*j], rs[2*j+1])
+		}
+	}
+}
+
+func BenchmarkEncodeValidASCII(b *testing.B) {
+	data := []rune{'h', 'e', 'l', 'l', 'o'}
+	for i := 0; i < b.N; i++ {
+		Encode(data)
+	}
+}
+
+func BenchmarkEncodeValidJapaneseChars(b *testing.B) {
+	data := []rune{'日', '本', '語'}
+	for i := 0; i < b.N; i++ {
+		Encode(data)
+	}
+}
+
+func BenchmarkEncodeRune(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, u := range []rune{'𝓐', '𝓑', '𝓒', '𝓓', '𝓔'} {
+			EncodeRune(u)
+		}
+	}
+}
diff --git a/libgo/go/unicode/utf8/utf8.go b/libgo/go/unicode/utf8/utf8.go
index bbaf14aab8f..9d35be6c065 100644
--- a/libgo/go/unicode/utf8/utf8.go
+++ b/libgo/go/unicode/utf8/utf8.go
@@ -341,7 +341,7 @@ func RuneLen(r rune) int {
 // EncodeRune writes into p (which must be large enough) the UTF-8 encoding of the rune.
 // It returns the number of bytes written.
 func EncodeRune(p []byte, r rune) int {
-	// Negative values are erroneous.  Making it unsigned addresses the problem.
+	// Negative values are erroneous. Making it unsigned addresses the problem.
 	switch i := uint32(r); {
 	case i <= rune1Max:
 		p[0] = byte(r)
@@ -367,7 +367,7 @@ func EncodeRune(p []byte, r rune) int {
 	}
 }
 
-// RuneCount returns the number of runes in p.  Erroneous and short
+// RuneCount returns the number of runes in p. Erroneous and short
 // encodings are treated as single runes of width 1 byte.
 func RuneCount(p []byte) int {
 	np := len(p)
@@ -441,7 +441,7 @@ func RuneCountInString(s string) (n int) {
 }
 
 // RuneStart reports whether the byte could be the first byte of an encoded,
-// possibly invalid rune.  Second and subsequent bytes always have the top two
+// possibly invalid rune. Second and subsequent bytes always have the top two
 // bits set to 10.
 func RuneStart(b byte) bool { return b&0xC0 != 0x80 }
 
diff --git a/libgo/merge.sh b/libgo/merge.sh
index 24f63d9df6b..373937cf796 100755
--- a/libgo/merge.sh
+++ b/libgo/merge.sh
@@ -137,15 +137,7 @@ merge_c() {
   fi
 }
 
-if test -f VERSION; then
-  if ! cmp -s ${NEWDIR}/VERSION VERSION; then
-    cp ${NEWDIR}/VERSION .
-  fi
-else
-  if test -f ${NEWDIR}/VERSION; then
-    cp ${NEWDIR}/VERSION .
-  fi
-fi
+echo ${rev} > VERSION
 
 (cd ${NEWDIR}/src && find . -name '*.go' -print) | while read f; do
   oldfile=${OLDDIR}/src/$f
diff --git a/libgo/mksysinfo.sh b/libgo/mksysinfo.sh
index 1271e1a550f..026bef2dbf9 100755
--- a/libgo/mksysinfo.sh
+++ b/libgo/mksysinfo.sh
@@ -97,6 +97,7 @@ cat > sysinfo.c <<EOF
 #include <unistd.h>
 #include <netdb.h>
 #include <pwd.h>
+#include <grp.h>
 #if defined(HAVE_LINUX_FILTER_H)
 #include <linux/filter.h>
 #endif
@@ -428,6 +429,10 @@ if ! grep '^const AF_LOCAL ' ${OUT} >/dev/null 2>&1; then
   fi
 fi
 
+# sysconf constants.
+grep '^const __SC' gen-sysinfo.go |
+  sed -e 's/^\(const \)__\(SC[^= ]*\)\(.*\)$/\1\2 = __\2/' >> ${OUT}
+
 # pathconf constants.
 grep '^const __PC' gen-sysinfo.go |
   sed -e 's/^\(const \)__\(PC[^= ]*\)\(.*\)$/\1\2 = __\2/' >> ${OUT}
@@ -906,6 +911,12 @@ grep '^type _passwd ' gen-sysinfo.go | \
       -e 's/ pw_/ Pw_/g' \
     >> ${OUT}
 
+# The group struct.
+grep '^type _group ' gen-sysinfo.go | \
+    sed -e 's/_group/Group/' \
+      -e 's/ gr_/ Gr_/g' \
+    >> ${OUT}
+
 # The ioctl flags for the controlling TTY.
 grep '^const _TIOC' gen-sysinfo.go | \
     grep -v '_val =' | \
diff --git a/libgo/runtime/chan.goc b/libgo/runtime/chan.goc
index 0cc823d8ac7..44402d4481e 100644
--- a/libgo/runtime/chan.goc
+++ b/libgo/runtime/chan.goc
@@ -948,7 +948,7 @@ sclose:
 typedef struct runtimeSelect runtimeSelect;
 struct runtimeSelect
 {
-	uintptr dir;
+	intgo dir;
 	ChanType *typ;
 	Hchan *ch;
 	byte *val;
diff --git a/libgo/runtime/chan.h b/libgo/runtime/chan.h
index 70b0b9d9090..473f365b921 100644
--- a/libgo/runtime/chan.h
+++ b/libgo/runtime/chan.h
@@ -17,6 +17,7 @@ struct	SudoG
 	SudoG*	link;
 	int64	releasetime;
 	byte*	elem;		// data element
+	uint32  ticket;
 };
 
 struct	WaitQ
diff --git a/libgo/runtime/go-caller.c b/libgo/runtime/go-caller.c
index d6901e07377..2a24a50f731 100644
--- a/libgo/runtime/go-caller.c
+++ b/libgo/runtime/go-caller.c
@@ -25,6 +25,7 @@ struct caller
   String fn;
   String file;
   intgo line;
+  intgo index;
 };
 
 /* Collect file/line information for a PC value.  If this is called
@@ -45,6 +46,12 @@ callback (void *data, uintptr_t pc __attribute__ ((unused)),
   c->file = runtime_gostringnocopy ((const byte *) filename);
   c->line = lineno;
 
+  if (c->index == 0)
+    return 1;
+
+  if (c->index > 0)
+    --c->index;
+
   return 0;
 }
 
@@ -102,14 +109,17 @@ __go_get_backtrace_state ()
   return back_state;
 }
 
-/* Return function/file/line information for PC.  */
+/* Return function/file/line information for PC.  The index parameter
+   is the entry on the stack of inlined functions; -1 means the last
+   one.  */
 
 _Bool
-__go_file_line (uintptr pc, String *fn, String *file, intgo *line)
+__go_file_line (uintptr pc, int index, String *fn, String *file, intgo *line)
 {
   struct caller c;
 
   runtime_memclr (&c, sizeof c);
+  c.index = index;
   backtrace_pcinfo (__go_get_backtrace_state (), pc, callback,
 		    error_callback, &c);
   *fn = c.fn;
@@ -186,7 +196,7 @@ FuncForPC (uintptr_t pc)
   intgo line;
   uintptr_t val;
 
-  if (!__go_file_line (pc, &fn, &file, &line))
+  if (!__go_file_line (pc, -1, &fn, &file, &line))
     return NULL;
 
   ret = (Func *) runtime_malloc (sizeof (*ret));
@@ -219,7 +229,7 @@ runtime_funcline_go (Func *f __attribute__((unused)), uintptr targetpc)
   struct funcline_go_return ret;
   String fn;
 
-  if (!__go_file_line (targetpc, &fn, &ret.retfile,  &ret.retline))
+  if (!__go_file_line (targetpc, -1, &fn, &ret.retfile,  &ret.retline))
     runtime_memclr (&ret, sizeof ret);
   return ret;
 }
@@ -245,3 +255,45 @@ runtime_funcentry_go (Func *f)
 {
   return f->entry;
 }
+
+/* Look up file and line information for Frames.Next.  */
+
+struct funcframe_return
+{
+  Func* retfunc;
+  String retfile;
+  intgo retline;
+};
+
+struct funcframe_return
+runtime_funcframe (uintptr pc, int index)
+  __asm__ (GOSYM_PREFIX "runtime.funcframe");
+
+struct funcframe_return
+runtime_funcframe (uintptr pc, int index)
+{
+  struct funcframe_return ret;
+  String fn;
+  Func* func;
+  uintptr_t val;
+
+  // Subtract 1 from PC to undo the 1 we added in callback in go-callers.c.
+  --pc;
+
+  if (!__go_file_line (pc, index, &fn, &ret.retfile, &ret.retline))
+    runtime_memclr (&ret, sizeof ret);
+  else
+    {
+      func = (Func *) runtime_malloc (sizeof (*func));
+      func->name = fn;
+
+      if (__go_symbol_value (pc, &val))
+	func->entry = val;
+      else
+	func->entry = 0;
+
+      ret.retfunc = func;
+    }
+
+  return ret;
+}
diff --git a/libgo/runtime/malloc.goc b/libgo/runtime/malloc.goc
index 0d8629277f8..c111a0eeefd 100644
--- a/libgo/runtime/malloc.goc
+++ b/libgo/runtime/malloc.goc
@@ -996,3 +996,7 @@ badfunc:
 throw:
 	runtime_throw("runtime.SetFinalizer");
 }
+
+func KeepAlive(x Eface) {
+	USED(x);
+}
diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
index c6ac972bd41..defb0a59bb1 100644
--- a/libgo/runtime/proc.c
+++ b/libgo/runtime/proc.c
@@ -686,7 +686,7 @@ runtime_printcreatedby(G *g)
 		String file;
 		intgo line;
 
-		if(__go_file_line(g->gopc - 1, &fn, &file, &line)) {
+		if(__go_file_line(g->gopc - 1, -1, &fn, &file, &line)) {
 			runtime_printf("created by %S\n", fn);
 			runtime_printf("\t%S:%D\n", file, (int64) line);
 		}
diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h
index 73c46e9117f..ba5eab78c78 100644
--- a/libgo/runtime/runtime.h
+++ b/libgo/runtime/runtime.h
@@ -835,7 +835,7 @@ extern uintptr runtime_stacks_sys;
 
 struct backtrace_state;
 extern struct backtrace_state *__go_get_backtrace_state(void);
-extern _Bool __go_file_line(uintptr, String*, String*, intgo *);
+extern _Bool __go_file_line(uintptr, int, String*, String*, intgo *);
 extern byte* runtime_progname();
 extern void runtime_main(void*);
 extern uint32 runtime_in_callers;
diff --git a/libgo/runtime/sema.goc b/libgo/runtime/sema.goc
index 50f0e973d70..b49c7b71051 100644
--- a/libgo/runtime/sema.goc
+++ b/libgo/runtime/sema.goc
@@ -19,6 +19,7 @@
 
 package sync
 #include "runtime.h"
+#include "chan.h"
 #include "arch.h"
 
 typedef struct SemaWaiter SemaWaiter;
@@ -98,6 +99,13 @@ cansemacquire(uint32 volatile *addr)
 	return 0;
 }
 
+static void readyWithTime(SudoG* s, int traceskip __attribute__ ((unused))) {
+	if (s->releasetime != 0) {
+		s->releasetime = runtime_cputicks();
+	}
+	runtime_ready(s->g);
+}
+
 void
 runtime_semacquire(uint32 volatile *addr, bool profile)
 {
@@ -297,3 +305,167 @@ func runtime_Syncsemrelease(s *SyncSema, n uint32) {
 	} else
 		runtime_unlock(s);
 }
+
+// notifyList is a ticket-based notification list used to implement sync.Cond.
+//
+// It must be kept in sync with the sync package.
+typedef struct {
+	// wait is the ticket number of the next waiter. It is atomically
+	// incremented outside the lock.
+	uint32 wait;
+
+	// notify is the ticket number of the next waiter to be notified. It can
+	// be read outside the lock, but is only written to with lock held.
+	//
+	// Both wait & notify can wrap around, and such cases will be correctly
+	// handled as long as their "unwrapped" difference is bounded by 2^31.
+	// For this not to be the case, we'd need to have 2^31+ goroutines
+	// blocked on the same condvar, which is currently not possible.
+	uint32 notify;
+
+	// List of parked waiters.
+	Lock lock;
+	SudoG* head;
+	SudoG* tail;
+} notifyList;
+
+// less checks if a < b, considering a & b running counts that may overflow the
+// 32-bit range, and that their "unwrapped" difference is always less than 2^31.
+static bool less(uint32 a, uint32 b) {
+	return (int32)(a-b) < 0;
+}
+
+// notifyListAdd adds the caller to a notify list such that it can receive
+// notifications. The caller must eventually call notifyListWait to wait for
+// such a notification, passing the returned ticket number.
+//go:linkname notifyListAdd sync.runtime_notifyListAdd
+func runtime_notifyListAdd(l *notifyList) (r uint32) {
+	// This may be called concurrently, for example, when called from
+	// sync.Cond.Wait while holding a RWMutex in read mode.
+	r = runtime_xadd(&l->wait, 1) - 1;
+}
+
+// notifyListWait waits for a notification. If one has been sent since
+// notifyListAdd was called, it returns immediately. Otherwise, it blocks.
+//go:linkname notifyListWait sync.runtime_notifyListWait
+func runtime_notifyListWait(l *notifyList, t uint32) {
+	SudoG s;
+	int64 t0;
+
+	runtime_lock(&l->lock);
+
+	// Return right away if this ticket has already been notified.
+	if (less(t, l->notify)) {
+		runtime_unlock(&l->lock);
+		return;
+	}
+
+	// Enqueue itself.
+	runtime_memclr(&s, sizeof(s));
+	s.g = runtime_g();
+	s.ticket = t;
+	s.releasetime = 0;
+	t0 = 0;
+	if (runtime_blockprofilerate > 0) {
+		t0 = runtime_cputicks();
+		s.releasetime = -1;
+	}
+	if (l->tail == nil) {
+		l->head = &s;
+	} else {
+		l->tail->link = &s;
+	}
+	l->tail = &s;
+	runtime_parkunlock(&l->lock, "semacquire");
+	if (t0 != 0) {
+		runtime_blockevent(s.releasetime-t0, 2);
+	}
+}
+
+// notifyListNotifyAll notifies all entries in the list.
+//go:linkname notifyListNotifyAll sync.runtime_notifyListNotifyAll
+func runtime_notifyListNotifyAll(l *notifyList) {
+	SudoG *s;
+
+	// Fast-path: if there are no new waiters since the last notification
+	// we don't need to acquire the lock.
+	if (runtime_atomicload(&l->wait) == runtime_atomicload(&l->notify)) {
+		return;
+	}
+
+	// Pull the list out into a local variable, waiters will be readied
+	// outside the lock.
+	runtime_lock(&l->lock);
+	s = l->head;
+	l->head = nil;
+	l->tail = nil;
+
+	// Update the next ticket to be notified. We can set it to the current
+	// value of wait because any previous waiters are already in the list
+	// or will notice that they have already been notified when trying to
+	// add themselves to the list.
+	runtime_atomicstore(&l->notify, runtime_atomicload(&l->wait));
+	runtime_unlock(&l->lock);
+
+	// Go through the local list and ready all waiters.
+	while (s != nil) {
+		SudoG* next = s->link;
+		s->link = nil;
+		readyWithTime(s, 4);
+		s = next;
+	}
+}
+
+// notifyListNotifyOne notifies one entry in the list.
+//go:linkname notifyListNotifyOne sync.runtime_notifyListNotifyOne
+func runtime_notifyListNotifyOne(l *notifyList) {
+	uint32 t;
+	SudoG *p;
+	SudoG *s;
+
+	// Fast-path: if there are no new waiters since the last notification
+	// we don't need to acquire the lock at all.
+	if (runtime_atomicload(&l->wait) == runtime_atomicload(&l->notify)) {
+		return;
+	}
+
+	runtime_lock(&l->lock);
+
+	// Re-check under the lock if we need to do anything.
+	t = l->notify;
+	if (t == runtime_atomicload(&l->wait)) {
+		runtime_unlock(&l->lock);
+		return;
+	}
+
+	// Update the next notify ticket number, and try to find the G that
+	// needs to be notified. If it hasn't made it to the list yet we won't
+	// find it, but it won't park itself once it sees the new notify number.
+	runtime_atomicstore(&l->notify, t+1);
+	for (p = nil, s = l->head; s != nil; p = s, s = s->link) {
+		if (s->ticket == t) {
+			SudoG *n = s->link;
+			if (p != nil) {
+				p->link = n;
+			} else {
+				l->head = n;
+			}
+			if (n == nil) {
+				l->tail = p;
+			}
+			runtime_unlock(&l->lock);
+			s->link = nil;
+			readyWithTime(s, 4);
+			return;
+		}
+	}
+	runtime_unlock(&l->lock);
+}
+
+//go:linkname notifyListCheck sync.runtime_notifyListCheck
+func runtime_notifyListCheck(sz uintptr) {
+	if (sz != sizeof(notifyList)) {
+		runtime_printf("runtime: bad notifyList size\n");
+		runtime_throw("bad notifyList size");
+	}
+}