2016-04-15 Basile Starynkevitch <basile@starynkevitch.net>

	{{merging with even more of GCC 6, using subversion 1.9
	svn merge -r229501:229700 ^/trunk
	}}



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/melt-branch@235005 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 80 insertions, 6 deletions

diff --git a/libgo/go/io/io.go b/libgo/go/io/io.go
index 7507a84929f..8851eaf00ab 100644
--- a/libgo/go/io/io.go
+++ b/libgo/go/io/io.go
@@ -54,7 +54,7 @@ var ErrNoProgress = errors.New("multiple Read calls return no data or error")
 // 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 0, EOF regardless.
+// return 0, EOF.
 //
 // Callers should always process the n > 0 bytes returned before
 // considering the error err.  Doing so correctly handles I/O errors
@@ -273,8 +273,8 @@ type stringWriter interface {
 	WriteString(s string) (n int, err error)
 }
 
-// WriteString writes the contents of the string s to w, which accepts an array of bytes.
-// If w already implements a WriteString method, it is invoked directly.
+// 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.
 func WriteString(w Writer, s string) (n int, err error) {
 	if sw, ok := w.(stringWriter); ok {
 		return sw.WriteString(s)
@@ -348,6 +348,23 @@ func CopyN(dst Writer, src Reader, n int64) (written int64, err error) {
 // Otherwise, if dst implements the ReaderFrom interface,
 // the copy is implemented by calling dst.ReadFrom(src).
 func Copy(dst Writer, src Reader) (written int64, err error) {
+	return copyBuffer(dst, src, nil)
+}
+
+// CopyBuffer is identical to Copy except that it stages through the
+// provided buffer (if one is required) rather than allocating a
+// temporary one. If buf is nil, one is allocated; otherwise if it has
+// zero length, CopyBuffer panics.
+func CopyBuffer(dst Writer, src Reader, buf []byte) (written int64, err error) {
+	if buf != nil && len(buf) == 0 {
+		panic("empty buffer in io.CopyBuffer")
+	}
+	return copyBuffer(dst, src, buf)
+}
+
+// copyBuffer is the actual implementation of Copy and CopyBuffer.
+// if buf is nil, one is allocated.
+func copyBuffer(dst Writer, src Reader, buf []byte) (written int64, err error) {
 	// If the reader has a WriteTo method, use it to do the copy.
 	// Avoids an allocation and a copy.
 	if wt, ok := src.(WriterTo); ok {
@@ -357,7 +374,9 @@ func Copy(dst Writer, src Reader) (written int64, err error) {
 	if rt, ok := dst.(ReaderFrom); ok {
 		return rt.ReadFrom(src)
 	}
-	buf := make([]byte, 32*1024)
+	if buf == nil {
+		buf = make([]byte, 32*1024)
+	}
 	for {
 		nr, er := src.Read(buf)
 		if nr > 0 {
diff --git a/libgo/go/io/io_test.go b/libgo/go/io/io_test.go
index 57db1fbf0bf..e892574b0b5 100644
--- a/libgo/go/io/io_test.go
+++ b/libgo/go/io/io_test.go
@@ -20,7 +20,7 @@ type Buffer struct {
 	WriterTo   // conflicts with and hides bytes.Buffer's WriterTo.
 }
 
-// Simple tests, primarily to verify the ReadFrom and WriteTo callouts inside Copy and CopyN.
+// Simple tests, primarily to verify the ReadFrom and WriteTo callouts inside Copy, CopyBuffer and CopyN.
 
 func TestCopy(t *testing.T) {
 	rb := new(Buffer)
@@ -32,6 +32,26 @@ func TestCopy(t *testing.T) {
 	}
 }
 
+func TestCopyBuffer(t *testing.T) {
+	rb := new(Buffer)
+	wb := new(Buffer)
+	rb.WriteString("hello, world.")
+	CopyBuffer(wb, rb, make([]byte, 1)) // Tiny buffer to keep it honest.
+	if wb.String() != "hello, world." {
+		t.Errorf("CopyBuffer did not work properly")
+	}
+}
+
+func TestCopyBufferNil(t *testing.T) {
+	rb := new(Buffer)
+	wb := new(Buffer)
+	rb.WriteString("hello, world.")
+	CopyBuffer(wb, rb, nil) // Should allocate a buffer.
+	if wb.String() != "hello, world." {
+		t.Errorf("CopyBuffer did not work properly")
+	}
+}
+
 func TestCopyReadFrom(t *testing.T) {
 	rb := new(Buffer)
 	wb := new(bytes.Buffer) // implements ReadFrom.
@@ -78,6 +98,34 @@ func TestCopyPriority(t *testing.T) {
 	}
 }
 
+type zeroErrReader struct {
+	err error
+}
+
+func (r zeroErrReader) Read(p []byte) (int, error) {
+	return copy(p, []byte{0}), r.err
+}
+
+type errWriter struct {
+	err error
+}
+
+func (w errWriter) Write([]byte) (int, error) {
+	return 0, w.err
+}
+
+// In case a Read results in an error with non-zero bytes read, and
+// the subsequent Write also results in an error, the error from Write
+// is returned, as it is the one that prevented progressing further.
+func TestCopyReadErrWriteErr(t *testing.T) {
+	er, ew := errors.New("readError"), errors.New("writeError")
+	r, w := zeroErrReader{err: er}, errWriter{err: ew}
+	n, err := Copy(w, r)
+	if n != 0 || err != ew {
+		t.Errorf("Copy(zeroErrReader, errWriter) = %d, %v; want 0, writeError", n, err)
+	}
+}
+
 func TestCopyN(t *testing.T) {
 	rb := new(Buffer)
 	wb := new(Buffer)
diff --git a/libgo/go/io/ioutil/tempfile.go b/libgo/go/io/ioutil/tempfile.go
index 4a06e9756fb..61d4a7ad37d 100644
--- a/libgo/go/io/ioutil/tempfile.go
+++ b/libgo/go/io/ioutil/tempfile.go
@@ -55,7 +55,9 @@ func TempFile(dir, prefix string) (f *os.File, err error) {
 		f, err = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
 		if os.IsExist(err) {
 			if nconflict++; nconflict > 10 {
+				randmu.Lock()
 				rand = reseed()
+				randmu.Unlock()
 			}
 			continue
 		}
@@ -82,7 +84,9 @@ func TempDir(dir, prefix string) (name string, err error) {
 		err = os.Mkdir(try, 0700)
 		if os.IsExist(err) {
 			if nconflict++; nconflict > 10 {
+				randmu.Lock()
 				rand = reseed()
+				randmu.Unlock()
 			}
 			continue
 		}
diff --git a/libgo/go/io/pipe.go b/libgo/go/io/pipe.go
index f65354a7f25..179515e78d3 100644
--- a/libgo/go/io/pipe.go
+++ b/libgo/go/io/pipe.go
@@ -168,7 +168,10 @@ func (w *PipeWriter) Close() error {
 }
 
 // CloseWithError closes the writer; subsequent reads from the
-// read half of the pipe will return no bytes and the error err.
+// read half of the pipe will return no bytes and the error err,
+// or EOF if err is nil.
+//
+// CloseWithError always returns nil.
 func (w *PipeWriter) CloseWithError(err error) error {
 	w.p.wclose(err)
 	return nil