bytes.Buffer: read of 0 bytes at EOF shouldn't be an EOF
This corner case arose doing an RPC with a empty-slice payload. Ouch.
R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/5505073
diff --git a/src/pkg/bytes/buffer.go b/src/pkg/bytes/buffer.go
index e66ac02..066023a 100644
--- a/src/pkg/bytes/buffer.go
+++ b/src/pkg/bytes/buffer.go
@@ -200,13 +200,16 @@
// 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 adb9330..d0af11f 100644
--- a/src/pkg/bytes/buffer_test.go
+++ b/src/pkg/bytes/buffer_test.go
@@ -373,3 +373,16 @@
}
}
}
+
+// 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)
+ }
+}
