diff --git a/src/pkg/bytes/buffer.go b/src/pkg/bytes/buffer.go index e66ac026e5..066023a3ec 100644 --- a/src/pkg/bytes/buffer.go +++ b/src/pkg/bytes/buffer.go @@ -200,13 +200,16 @@ 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 -// buffer has no data to return, err is io.EOF even if len(p) is zero; +// 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) { b.lastRead = opInvalid if b.off >= len(b.buf) { // Buffer is empty, reset to recover space. b.Truncate(0) + if len(p) == 0 { + return + } return 0, io.EOF } n = copy(p, b.buf[b.off:]) diff --git a/src/pkg/bytes/buffer_test.go b/src/pkg/bytes/buffer_test.go index adb93302a5..d0af11f104 100644 --- a/src/pkg/bytes/buffer_test.go +++ b/src/pkg/bytes/buffer_test.go @@ -373,3 +373,16 @@ func TestReadBytes(t *testing.T) { } } } + +// Was a bug: used to give EOF reading empty slice at EOF. +func TestReadEmptyAtEOF(t *testing.T) { + b := new(Buffer) + slice := make([]byte, 0) + n, err := b.Read(slice) + if err != nil { + t.Errorf("read error: %v", err) + } + if n != 0 { + t.Errorf("wrong count; got %d want 0", n) + } +}