plumbing: format/packfile, Fix data race and resource leak.

plumbing/format/packfile/diff_delta.go

@@ -40,17 +40,17 @@ func getDelta(index *deltaIndex, base, target plumbing.EncodedObject) (plumbing.
 	defer tr.Close()
 
 	bb := bufPool.Get().(*bytes.Buffer)
-	bb.Reset()
 	defer bufPool.Put(bb)
+	bb.Reset()
 
 	_, err = bb.ReadFrom(br)
 	if err != nil {
 		return nil, err
 	}
 
 	tb := bufPool.Get().(*bytes.Buffer)
-	tb.Reset()
 	defer bufPool.Put(tb)
+	tb.Reset()
 
 	_, err = tb.ReadFrom(tr)
 	if err != nil {
@@ -77,6 +77,7 @@ func DiffDelta(src, tgt []byte) []byte {
 
 func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte {
 	buf := bufPool.Get().(*bytes.Buffer)
+	defer bufPool.Put(buf)
 	buf.Reset()
 	buf.Write(deltaEncodeSize(len(src)))
 	buf.Write(deltaEncodeSize(len(tgt)))
@@ -86,6 +87,7 @@ func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte {
 	}
 
 	ibuf := bufPool.Get().(*bytes.Buffer)
+	defer bufPool.Put(ibuf)
 	ibuf.Reset()
 	for i := 0; i < len(tgt); i++ {
 		offset, l := index.findMatch(src, tgt, i)
@@ -127,12 +129,9 @@ func diffDelta(index *deltaIndex, src []byte, tgt []byte) []byte {
 	}
 
 	encodeInsertOperation(ibuf, buf)
-	bytes := buf.Bytes()
-
-	bufPool.Put(buf)
-	bufPool.Put(ibuf)
 
-	return bytes
+	// buf.Bytes() is only valid until the next modifying operation on the buffer. Copy it.
+	return append([]byte{}, buf.Bytes()...)
 }
 
 func encodeInsertOperation(ibuf, buf *bytes.Buffer) {

plumbing/format/packfile/packfile.go

@@ -133,8 +133,8 @@ func (p *Packfile) getObjectSize(h *ObjectHeader) (int64, error) {
 		return h.Length, nil
 	case plumbing.REFDeltaObject, plumbing.OFSDeltaObject:
 		buf := bufPool.Get().(*bytes.Buffer)
-		buf.Reset()
 		defer bufPool.Put(buf)
+		buf.Reset()
 
 		if _, _, err := p.s.NextObject(buf); err != nil {
 			return 0, err
@@ -222,11 +222,11 @@ func (p *Packfile) getNextObject(h *ObjectHeader, hash plumbing.Hash) (plumbing.
 		// optimization only if the expanded version of the object still meets
 		// the small object threshold condition.
 		buf := bufPool.Get().(*bytes.Buffer)
+		defer bufPool.Put(buf)
 		buf.Reset()
 		if _, _, err := p.s.NextObject(buf); err != nil {
 			return nil, err
 		}
-		defer bufPool.Put(buf)
 
 		size = p.getDeltaObjectSize(buf)
 		if size <= smallObjectThreshold {
@@ -321,12 +321,12 @@ func (p *Packfile) fillRegularObjectContent(obj plumbing.EncodedObject) error {
 
 func (p *Packfile) fillREFDeltaObjectContent(obj plumbing.EncodedObject, ref plumbing.Hash) error {
 	buf := bufPool.Get().(*bytes.Buffer)
+	defer bufPool.Put(buf)
 	buf.Reset()
 	_, _, err := p.s.NextObject(buf)
 	if err != nil {
 		return err
 	}
-	defer bufPool.Put(buf)
 
 	return p.fillREFDeltaObjectContentWithBuffer(obj, ref, buf)
 }
@@ -351,12 +351,12 @@ func (p *Packfile) fillREFDeltaObjectContentWithBuffer(obj plumbing.EncodedObjec
 
 func (p *Packfile) fillOFSDeltaObjectContent(obj plumbing.EncodedObject, offset int64) error {
 	buf := bufPool.Get().(*bytes.Buffer)
+	defer bufPool.Put(buf)
 	buf.Reset()
 	_, _, err := p.s.NextObject(buf)
 	if err != nil {
 		return err
 	}
-	defer bufPool.Put(buf)
 
 	return p.fillOFSDeltaObjectContentWithBuffer(obj, offset, buf)
 }