Make file descriptors close-on-exec when possible.

This simplifies Emacs a bit, since it no longer needs to worry
about closing file descriptors by hand in some cases.
It also fixes some unlikely races.  Not all such races, as
libraries often open files internally without setting
close-on-exec, but it's an improvement.
* admin/merge-gnulib (GNULIB_MODULES): Add fcntl, pipe2.
(GNULIB_TOOL_FLAGS): Avoid binary-io, close.  Do not avoid fcntl.
* configure.ac (mkostemp): New function to check for.
(PTY_OPEN): Pass O_CLOEXEC to posix_openpt.
* lib/fcntl.c, lib/getdtablesize.c, lib/pipe2.c, m4/fcntl.m4:
* m4/getdtablesize.m4, m4/pipe2.m4: New files, taken from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* nt/gnulib.mk: Remove empty gl_GNULIB_ENABLED_verify section;
otherwise, gnulib-tool complains given close-on-exec changes.
* nt/inc/ms-w32.h (pipe): Remove.
* nt/mingw-cfg.site (ac_cv_func_fcntl, gl_cv_func_fcntl_f_dupfd_cloexec)
(gl_cv_func_fcntl_f_dupfd_works, ac_cv_func_pipe2): New vars.
* src/alloc.c (valid_pointer_p) [!WINDOWSNT]:
* src/callproc.c (Fcall_process) [!MSDOS]:
* src/emacs.c (main) [!DOS_NT]:
* src/nsterm.m (ns_term_init):
* src/process.c (create_process):
Use 'pipe2' with O_CLOEXEC instead of 'pipe'.
* src/emacs.c (Fcall_process_region) [HAVE_MKOSTEMP]:
* src/filelock.c (create_lock_file) [HAVE_MKOSTEMP]:
Prefer mkostemp with O_CLOEXEC to mkstemp.
* src/callproc.c (relocate_fd) [!WINDOWSNT]:
* src/emacs.c (main): Use F_DUPFD_CLOEXEC, not plain F_DUPFD.
No need to use fcntl (..., F_SETFD, FD_CLOEXEC), since we're
now using pipe2.
* src/filelock.c (create_lock_file) [! HAVE_MKOSTEMP]:
Make the resulting file descriptor close-on-exec.
* src/lisp.h, src/lread.c, src/process.c (close_load_descs, close_process_descs):
* src/lread.c (load_descriptor_list, load_descriptor_unwind):
Remove; no longer needed.  All uses removed.
* src/process.c (SOCK_CLOEXEC): Define to 0 if not supplied by system.
(close_on_exec, accept4, process_socket) [!SOCK_CLOEXEC]:
New functions.
(socket) [!SOCK_CLOEXEC]: Supply a substitute.
(Fmake_network_process, Fnetwork_interface_list):
(Fnetwork_interface_info, server_accept_connection):
Make newly-created socket close-on-exec.
* src/sysdep.c (emacs_open, emacs_fopen):
Make new-created descriptor close-on-exec.
* src/w32.c (fcntl): Support F_DUPFD_CLOEXEC well enough for Emacs.
* src/w32.c, src/w32.h (pipe2): Rename from 'pipe', with new flags arg.

Fixes: debbugs:14803

1 files changed, 27 insertions, 3 deletions

diff --git a/lib/gnulib.mk b/lib/gnulib.mk
index 4a84b1db261..9f9ac6c0583 100644
--- a/lib/gnulib.mk
+++ b/lib/gnulib.mk
@@ -21,7 +21,7 @@
 # the same distribution terms as the rest of that program.
 #
 # Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=dup --avoid=fchdir --avoid=fcntl --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=sigprocmask --avoid=sys_types --avoid=threadlib --makefile-name=gnulib.mk --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt c-ctype c-strcase careadlinkat close-stream crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ execinfo faccessat fcntl-h fdatasync fdopendir filemode fstatat fsync getloadavg getopt-gnu gettime gettimeofday ignore-value intprops largefile lstat manywarnings memrchr mktime pselect pthread_sigmask putenv qacl readlink readlinkat sig2str socklen stat-time stdalign stdarg stdbool stdio strftime strtoimax strtoumax symlink sys_stat sys_time time timer-time timespec-add timespec-sub unsetenv utimens warnings
+# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=binary-io --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=sigprocmask --avoid=sys_types --avoid=threadlib --makefile-name=gnulib.mk --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt c-ctype c-strcase careadlinkat close-stream crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ execinfo faccessat fcntl fcntl-h fdatasync fdopendir filemode fstatat fsync getloadavg getopt-gnu gettime gettimeofday ignore-value intprops largefile lstat manywarnings memrchr mktime pipe2 pselect pthread_sigmask putenv qacl readlink readlinkat sig2str socklen stat-time stdalign stdarg stdbool stdio strftime strtoimax strtoumax symlink sys_stat sys_time time timer-time timespec-add timespec-sub unsetenv utimens warnings
 
 
 MOSTLYCLEANFILES += core *.stackdump
@@ -296,6 +296,15 @@ EXTRA_libgnu_a_SOURCES += at-func.c faccessat.c
 
 ## end   gnulib module faccessat
 
+## begin gnulib module fcntl
+
+
+EXTRA_DIST += fcntl.c
+
+EXTRA_libgnu_a_SOURCES += fcntl.c
+
+## end   gnulib module fcntl
+
 ## begin gnulib module fcntl-h
 
 BUILT_SOURCES += fcntl.h
@@ -384,6 +393,17 @@ EXTRA_libgnu_a_SOURCES += fsync.c
 
 ## end   gnulib module fsync
 
+## begin gnulib module getdtablesize
+
+if gl_GNULIB_ENABLED_getdtablesize
+
+endif
+EXTRA_DIST += getdtablesize.c
+
+EXTRA_libgnu_a_SOURCES += getdtablesize.c
+
+## end   gnulib module getdtablesize
+
 ## begin gnulib module getgroups
 
 if gl_GNULIB_ENABLED_getgroups
@@ -568,6 +588,12 @@ EXTRA_DIST += pathmax.h
 
 ## end   gnulib module pathmax
 
+## begin gnulib module pipe2
+
+libgnu_a_SOURCES += pipe2.c
+
+## end   gnulib module pipe2
+
 ## begin gnulib module pselect
 
 
@@ -1704,9 +1730,7 @@ EXTRA_DIST += utimens.h
 
 ## begin gnulib module verify
 
-if gl_GNULIB_ENABLED_verify
 
-endif
 EXTRA_DIST += verify.h
 
 ## end   gnulib module verify