update go-git to v4.12.0 - fixes #7248 (#7249)

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/idxfile/idxfile.go

@@ -5,8 +5,9 @@ import (
 	"io"
 	"sort"
 
+	encbin "encoding/binary"
+
 	"gopkg.in/src-d/go-git.v4/plumbing"
-	"gopkg.in/src-d/go-git.v4/utils/binary"
 )
 
 const (
@@ -55,7 +56,8 @@ type MemoryIndex struct {
 	PackfileChecksum [20]byte
 	IdxChecksum      [20]byte
 
-	offsetHash map[int64]plumbing.Hash
+	offsetHash       map[int64]plumbing.Hash
+	offsetHashIsFull bool
 }
 
 var _ Index = (*MemoryIndex)(nil)
@@ -121,31 +123,32 @@ func (idx *MemoryIndex) FindOffset(h plumbing.Hash) (int64, error) {
 		return 0, plumbing.ErrObjectNotFound
 	}
 
-	return idx.getOffset(k, i)
+	offset := idx.getOffset(k, i)
+
+	if !idx.offsetHashIsFull {
+		// Save the offset for reverse lookup
+		if idx.offsetHash == nil {
+			idx.offsetHash = make(map[int64]plumbing.Hash)
+		}
+		idx.offsetHash[int64(offset)] = h
+	}
+
+	return int64(offset), nil
 }
 
 const isO64Mask = uint64(1) << 31
 
-func (idx *MemoryIndex) getOffset(firstLevel, secondLevel int) (int64, error) {
+func (idx *MemoryIndex) getOffset(firstLevel, secondLevel int) uint64 {
 	offset := secondLevel << 2
-	buf := bytes.NewBuffer(idx.Offset32[firstLevel][offset : offset+4])
-	ofs, err := binary.ReadUint32(buf)
-	if err != nil {
-		return -1, err
-	}
+	ofs := encbin.BigEndian.Uint32(idx.Offset32[firstLevel][offset : offset+4])
 
 	if (uint64(ofs) & isO64Mask) != 0 {
 		offset := 8 * (uint64(ofs) & ^isO64Mask)
-		buf := bytes.NewBuffer(idx.Offset64[offset : offset+8])
-		n, err := binary.ReadUint64(buf)
-		if err != nil {
-			return -1, err
-		}
-
-		return int64(n), nil
+		n := encbin.BigEndian.Uint64(idx.Offset64[offset : offset+8])
+		return n
 	}
 
-	return int64(ofs), nil
+	return uint64(ofs)
 }
 
 // FindCRC32 implements the Index interface.
@@ -156,25 +159,34 @@ func (idx *MemoryIndex) FindCRC32(h plumbing.Hash) (uint32, error) {
 		return 0, plumbing.ErrObjectNotFound
 	}
 
-	return idx.getCRC32(k, i)
+	return idx.getCRC32(k, i), nil
 }
 
-func (idx *MemoryIndex) getCRC32(firstLevel, secondLevel int) (uint32, error) {
+func (idx *MemoryIndex) getCRC32(firstLevel, secondLevel int) uint32 {
 	offset := secondLevel << 2
-	buf := bytes.NewBuffer(idx.CRC32[firstLevel][offset : offset+4])
-	return binary.ReadUint32(buf)
+	return encbin.BigEndian.Uint32(idx.CRC32[firstLevel][offset : offset+4])
 }
 
 // FindHash implements the Index interface.
 func (idx *MemoryIndex) FindHash(o int64) (plumbing.Hash, error) {
-	// Lazily generate the reverse offset/hash map if required.
-	if idx.offsetHash == nil {
-		if err := idx.genOffsetHash(); err != nil {
-			return plumbing.ZeroHash, err
+	var hash plumbing.Hash
+	var ok bool
+
+	if idx.offsetHash != nil {
+		if hash, ok = idx.offsetHash[o]; ok {
+			return hash, nil
 		}
 	}
 
-	hash, ok := idx.offsetHash[o]
+	// Lazily generate the reverse offset/hash map if required.
+	if !idx.offsetHashIsFull || idx.offsetHash == nil {
+		if err := idx.genOffsetHash(); err != nil {
+			return plumbing.ZeroHash, err
+		}
+
+		hash, ok = idx.offsetHash[o]
+	}
+
 	if !ok {
 		return plumbing.ZeroHash, plumbing.ErrObjectNotFound
 	}
@@ -190,23 +202,21 @@ func (idx *MemoryIndex) genOffsetHash() error {
 	}
 
 	idx.offsetHash = make(map[int64]plumbing.Hash, count)
+	idx.offsetHashIsFull = true
 
-	iter, err := idx.Entries()
-	if err != nil {
-		return err
-	}
-
-	for {
-		entry, err := iter.Next()
-		if err != nil {
-			if err == io.EOF {
-				return nil
-			}
-			return err
+	var hash plumbing.Hash
+	i := uint32(0)
+	for firstLevel, fanoutValue := range idx.Fanout {
+		mappedFirstLevel := idx.FanoutMapping[firstLevel]
+		for secondLevel := uint32(0); i < fanoutValue; i++ {
+			copy(hash[:], idx.Names[mappedFirstLevel][secondLevel*objectIDLength:])
+			offset := int64(idx.getOffset(mappedFirstLevel, int(secondLevel)))
+			idx.offsetHash[offset] = hash
+			secondLevel++
 		}
-
-		idx.offsetHash[int64(entry.Offset)] = entry.Hash
 	}
+
+	return nil
 }
 
 // Count implements the Index interface.
@@ -275,22 +285,11 @@ func (i *idxfileEntryIter) Next() (*Entry, error) {
 			continue
 		}
 
+		mappedFirstLevel := i.idx.FanoutMapping[i.firstLevel]
 		entry := new(Entry)
-		ofs := i.secondLevel * objectIDLength
-		copy(entry.Hash[:], i.idx.Names[i.idx.FanoutMapping[i.firstLevel]][ofs:])
-
-		pos := i.idx.FanoutMapping[entry.Hash[0]]
-
-		offset, err := i.idx.getOffset(pos, i.secondLevel)
-		if err != nil {
-			return nil, err
-		}
-		entry.Offset = uint64(offset)
-
-		entry.CRC32, err = i.idx.getCRC32(pos, i.secondLevel)
-		if err != nil {
-			return nil, err
-		}
+		copy(entry.Hash[:], i.idx.Names[mappedFirstLevel][i.secondLevel*objectIDLength:])
+		entry.Offset = i.idx.getOffset(mappedFirstLevel, i.secondLevel)
+		entry.CRC32 = i.idx.getCRC32(mappedFirstLevel, i.secondLevel)
 
 		i.secondLevel++
 		i.total++

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/index/decoder.go

@@ -1,6 +1,7 @@
 package index
 
 import (
+	"bufio"
 	"bytes"
 	"crypto/sha1"
 	"errors"
@@ -42,14 +43,17 @@ type Decoder struct {
 	r         io.Reader
 	hash      hash.Hash
 	lastEntry *Entry
+
+	extReader *bufio.Reader
 }
 
 // NewDecoder returns a new decoder that reads from r.
 func NewDecoder(r io.Reader) *Decoder {
 	h := sha1.New()
 	return &Decoder{
-		r:    io.TeeReader(r, h),
-		hash: h,
+		r:         io.TeeReader(r, h),
+		hash:      h,
+		extReader: bufio.NewReader(nil),
 	}
 }
 
@@ -184,11 +188,9 @@ func (d *Decoder) doReadEntryNameV4() (string, error) {
 
 func (d *Decoder) doReadEntryName(len uint16) (string, error) {
 	name := make([]byte, len)
-	if err := binary.Read(d.r, &name); err != nil {
-		return "", err
-	}
+	_, err := io.ReadFull(d.r, name[:])
 
-	return string(name), nil
+	return string(name), err
 }
 
 // Index entries are padded out to the next 8 byte alignment
@@ -279,20 +281,21 @@ func (d *Decoder) readExtension(idx *Index, header []byte) error {
 	return nil
 }
 
-func (d *Decoder) getExtensionReader() (io.Reader, error) {
+func (d *Decoder) getExtensionReader() (*bufio.Reader, error) {
 	len, err := binary.ReadUint32(d.r)
 	if err != nil {
 		return nil, err
 	}
 
-	return &io.LimitedReader{R: d.r, N: int64(len)}, nil
+	d.extReader.Reset(&io.LimitedReader{R: d.r, N: int64(len)})
+	return d.extReader, nil
 }
 
 func (d *Decoder) readChecksum(expected []byte, alreadyRead [4]byte) error {
 	var h plumbing.Hash
 	copy(h[:4], alreadyRead[:])
 
-	if err := binary.Read(d.r, h[4:]); err != nil {
+	if _, err := io.ReadFull(d.r, h[4:]); err != nil {
 		return err
 	}
 
@@ -326,7 +329,7 @@ func validateHeader(r io.Reader) (version uint32, err error) {
 }
 
 type treeExtensionDecoder struct {
-	r io.Reader
+	r *bufio.Reader
 }
 
 func (d *treeExtensionDecoder) Decode(t *Tree) error {
@@ -386,16 +389,13 @@ func (d *treeExtensionDecoder) readEntry() (*TreeEntry, error) {
 	}
 
 	e.Trees = i
-
-	if err := binary.Read(d.r, &e.Hash); err != nil {
-		return nil, err
-	}
+	_, err = io.ReadFull(d.r, e.Hash[:])
 
 	return e, nil
 }
 
 type resolveUndoDecoder struct {
-	r io.Reader
+	r *bufio.Reader
 }
 
 func (d *resolveUndoDecoder) Decode(ru *ResolveUndo) error {
@@ -433,7 +433,7 @@ func (d *resolveUndoDecoder) readEntry() (*ResolveUndoEntry, error) {
 
 	for s := range e.Stages {
 		var hash plumbing.Hash
-		if err := binary.Read(d.r, hash[:]); err != nil {
+		if _, err := io.ReadFull(d.r, hash[:]); err != nil {
 			return nil, err
 		}
 
@@ -462,7 +462,7 @@ func (d *resolveUndoDecoder) readStage(e *ResolveUndoEntry, s Stage) error {
 }
 
 type endOfIndexEntryDecoder struct {
-	r io.Reader
+	r *bufio.Reader
 }
 
 func (d *endOfIndexEntryDecoder) Decode(e *EndOfIndexEntry) error {
@@ -472,5 +472,6 @@ func (d *endOfIndexEntryDecoder) Decode(e *EndOfIndexEntry) error {
 		return err
 	}
 
-	return binary.Read(d.r, &e.Hash)
+	_, err = io.ReadFull(d.r, e.Hash[:])
+	return err
 }

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/packfile/common.go

@@ -2,6 +2,7 @@ package packfile
 
 import (
 	"bytes"
+	"compress/zlib"
 	"io"
 	"sync"
 
@@ -66,3 +67,12 @@ var bufPool = sync.Pool{
 		return bytes.NewBuffer(nil)
 	},
 }
+
+var zlibInitBytes = []byte{0x78, 0x9c, 0x01, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0x00, 0x01}
+
+var zlibReaderPool = sync.Pool{
+	New: func() interface{} {
+		r, _ := zlib.NewReader(bytes.NewReader(zlibInitBytes))
+		return r
+	},
+}

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/packfile/diff_delta.go

@@ -40,8 +40,8 @@ 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 {
@@ -49,8 +49,8 @@ func getDelta(index *deltaIndex, base, target plumbing.EncodedObject) (plumbing.
 	}
 
 	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) {

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/packfile/packfile.go

@@ -76,20 +76,18 @@ func (p *Packfile) Get(h plumbing.Hash) (plumbing.EncodedObject, error) {
 		return nil, err
 	}
 
-	return p.GetByOffset(offset)
+	return p.objectAtOffset(offset, h)
 }
 
-// GetByOffset retrieves the encoded object from the packfile with the given
+// GetByOffset retrieves the encoded object from the packfile at the given
 // offset.
 func (p *Packfile) GetByOffset(o int64) (plumbing.EncodedObject, error) {
 	hash, err := p.FindHash(o)
-	if err == nil {
-		if obj, ok := p.deltaBaseCache.Get(hash); ok {
-			return obj, nil
-		}
+	if err != nil {
+		return nil, err
 	}
 
-	return p.objectAtOffset(o)
+	return p.objectAtOffset(o, hash)
 }
 
 // GetSizeByOffset retrieves the size of the encoded object from the
@@ -122,23 +120,27 @@ func (p *Packfile) nextObjectHeader() (*ObjectHeader, error) {
 	return h, err
 }
 
+func (p *Packfile) getDeltaObjectSize(buf *bytes.Buffer) int64 {
+	delta := buf.Bytes()
+	_, delta = decodeLEB128(delta) // skip src size
+	sz, _ := decodeLEB128(delta)
+	return int64(sz)
+}
+
 func (p *Packfile) getObjectSize(h *ObjectHeader) (int64, error) {
 	switch h.Type {
 	case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject:
 		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
 		}
 
-		delta := buf.Bytes()
-		_, delta = decodeLEB128(delta) // skip src size
-		sz, _ := decodeLEB128(delta)
-		return int64(sz), nil
+		return p.getDeltaObjectSize(buf), nil
 	default:
 		return 0, ErrInvalidObject.AddDetails("type %q", h.Type)
 	}
@@ -176,10 +178,16 @@ func (p *Packfile) getObjectType(h *ObjectHeader) (typ plumbing.ObjectType, err
 		err = ErrInvalidObject.AddDetails("type %q", h.Type)
 	}
 
+	p.offsetToType[h.Offset] = typ
+
 	return
 }
 
-func (p *Packfile) objectAtOffset(offset int64) (plumbing.EncodedObject, error) {
+func (p *Packfile) objectAtOffset(offset int64, hash plumbing.Hash) (plumbing.EncodedObject, error) {
+	if obj, ok := p.cacheGet(hash); ok {
+		return obj, nil
+	}
+
 	h, err := p.objectHeaderAtOffset(offset)
 	if err != nil {
 		if err == io.EOF || isInvalid(err) {
@@ -188,27 +196,54 @@ func (p *Packfile) objectAtOffset(offset int64) (plumbing.EncodedObject, error)
 		return nil, err
 	}
 
+	return p.getNextObject(h, hash)
+}
+
+func (p *Packfile) getNextObject(h *ObjectHeader, hash plumbing.Hash) (plumbing.EncodedObject, error) {
+	var err error
+
 	// If we have no filesystem, we will return a MemoryObject instead
 	// of an FSObject.
 	if p.fs == nil {
-		return p.getNextObject(h)
+		return p.getNextMemoryObject(h)
 	}
 
-	// If the object is not a delta and it's small enough then read it
-	// completely into memory now since it is already read from disk
-	// into buffer anyway.
-	if h.Length <= smallObjectThreshold && h.Type != plumbing.OFSDeltaObject && h.Type != plumbing.REFDeltaObject {
-		return p.getNextObject(h)
-	}
+	// If the object is small enough then read it completely into memory now since
+	// it is already read from disk into buffer anyway. For delta objects we want
+	// to perform the optimization too, but we have to be careful about applying
+	// small deltas on big objects.
+	var size int64
+	if h.Length <= smallObjectThreshold {
+		if h.Type != plumbing.OFSDeltaObject && h.Type != plumbing.REFDeltaObject {
+			return p.getNextMemoryObject(h)
+		}
 
-	hash, err := p.FindHash(h.Offset)
-	if err != nil {
-		return nil, err
-	}
+		// For delta objects we read the delta data and apply the small object
+		// 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
+		}
 
-	size, err := p.getObjectSize(h)
-	if err != nil {
-		return nil, err
+		size = p.getDeltaObjectSize(buf)
+		if size <= smallObjectThreshold {
+			var obj = new(plumbing.MemoryObject)
+			obj.SetSize(size)
+			if h.Type == plumbing.REFDeltaObject {
+				err = p.fillREFDeltaObjectContentWithBuffer(obj, h.Reference, buf)
+			} else {
+				err = p.fillOFSDeltaObjectContentWithBuffer(obj, h.OffsetReference, buf)
+			}
+			return obj, err
+		}
+	} else {
+		size, err = p.getObjectSize(h)
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	typ, err := p.getObjectType(h)
@@ -231,25 +266,14 @@ func (p *Packfile) objectAtOffset(offset int64) (plumbing.EncodedObject, error)
 }
 
 func (p *Packfile) getObjectContent(offset int64) (io.ReadCloser, error) {
-	ref, err := p.FindHash(offset)
-	if err == nil {
-		obj, ok := p.cacheGet(ref)
-		if ok {
-			reader, err := obj.Reader()
-			if err != nil {
-				return nil, err
-			}
-
-			return reader, nil
-		}
-	}
-
 	h, err := p.objectHeaderAtOffset(offset)
 	if err != nil {
 		return nil, err
 	}
 
-	obj, err := p.getNextObject(h)
+	// getObjectContent is called from FSObject, so we have to explicitly
+	// get memory object here to avoid recursive cycle
+	obj, err := p.getNextMemoryObject(h)
 	if err != nil {
 		return nil, err
 	}
@@ -257,7 +281,7 @@ func (p *Packfile) getObjectContent(offset int64) (io.ReadCloser, error) {
 	return obj.Reader()
 }
 
-func (p *Packfile) getNextObject(h *ObjectHeader) (plumbing.EncodedObject, error) {
+func (p *Packfile) getNextMemoryObject(h *ObjectHeader) (plumbing.EncodedObject, error) {
 	var obj = new(plumbing.MemoryObject)
 	obj.SetSize(h.Length)
 	obj.SetType(h.Type)
@@ -278,6 +302,8 @@ func (p *Packfile) getNextObject(h *ObjectHeader) (plumbing.EncodedObject, error
 		return nil, err
 	}
 
+	p.offsetToType[h.Offset] = obj.Type()
+
 	return obj, nil
 }
 
@@ -295,12 +321,19 @@ 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
 	}
 
+	return p.fillREFDeltaObjectContentWithBuffer(obj, ref, buf)
+}
+
+func (p *Packfile) fillREFDeltaObjectContentWithBuffer(obj plumbing.EncodedObject, ref plumbing.Hash, buf *bytes.Buffer) error {
+	var err error
+
 	base, ok := p.cacheGet(ref)
 	if !ok {
 		base, err = p.Get(ref)
@@ -312,30 +345,31 @@ func (p *Packfile) fillREFDeltaObjectContent(obj plumbing.EncodedObject, ref plu
 	obj.SetType(base.Type())
 	err = ApplyDelta(obj, base, buf.Bytes())
 	p.cachePut(obj)
-	bufPool.Put(buf)
 
 	return err
 }
 
 func (p *Packfile) fillOFSDeltaObjectContent(obj plumbing.EncodedObject, offset int64) error {
-	buf := bytes.NewBuffer(nil)
+	buf := bufPool.Get().(*bytes.Buffer)
+	defer bufPool.Put(buf)
+	buf.Reset()
 	_, _, err := p.s.NextObject(buf)
 	if err != nil {
 		return err
 	}
 
-	var base plumbing.EncodedObject
-	var ok bool
+	return p.fillOFSDeltaObjectContentWithBuffer(obj, offset, buf)
+}
+
+func (p *Packfile) fillOFSDeltaObjectContentWithBuffer(obj plumbing.EncodedObject, offset int64, buf *bytes.Buffer) error {
 	hash, err := p.FindHash(offset)
-	if err == nil {
-		base, ok = p.cacheGet(hash)
+	if err != nil {
+		return err
 	}
 
-	if !ok {
-		base, err = p.GetByOffset(offset)
-		if err != nil {
-			return err
-		}
+	base, err := p.objectAtOffset(offset, hash)
+	if err != nil {
+		return err
 	}
 
 	obj.SetType(base.Type())
@@ -414,6 +448,11 @@ func (p *Packfile) ID() (plumbing.Hash, error) {
 	return hash, nil
 }
 
+// Scanner returns the packfile's Scanner
+func (p *Packfile) Scanner() *Scanner {
+	return p.s
+}
+
 // Close the packfile and its resources.
 func (p *Packfile) Close() error {
 	closer, ok := p.file.(io.Closer)
@@ -437,14 +476,50 @@ func (i *objectIter) Next() (plumbing.EncodedObject, error) {
 			return nil, err
 		}
 
-		obj, err := i.p.GetByOffset(int64(e.Offset))
+		if i.typ != plumbing.AnyObject {
+			if typ, ok := i.p.offsetToType[int64(e.Offset)]; ok {
+				if typ != i.typ {
+					continue
+				}
+			} else if obj, ok := i.p.cacheGet(e.Hash); ok {
+				if obj.Type() != i.typ {
+					i.p.offsetToType[int64(e.Offset)] = obj.Type()
+					continue
+				}
+				return obj, nil
+			} else {
+				h, err := i.p.objectHeaderAtOffset(int64(e.Offset))
+				if err != nil {
+					return nil, err
+				}
+
+				if h.Type == plumbing.REFDeltaObject || h.Type == plumbing.OFSDeltaObject {
+					typ, err := i.p.getObjectType(h)
+					if err != nil {
+						return nil, err
+					}
+					if typ != i.typ {
+						i.p.offsetToType[int64(e.Offset)] = typ
+						continue
+					}
+					// getObjectType will seek in the file so we cannot use getNextObject safely
+					return i.p.objectAtOffset(int64(e.Offset), e.Hash)
+				} else {
+					if h.Type != i.typ {
+						i.p.offsetToType[int64(e.Offset)] = h.Type
+						continue
+					}
+					return i.p.getNextObject(h, e.Hash)
+				}
+			}
+		}
+
+		obj, err := i.p.objectAtOffset(int64(e.Offset), e.Hash)
 		if err != nil {
 			return nil, err
 		}
 
-		if i.typ == plumbing.AnyObject || obj.Type() == i.typ {
-			return obj, nil
-		}
+		return obj, nil
 	}
 }
 

vendor/gopkg.in/src-d/go-git.v4/plumbing/format/packfile/scanner.go

@@ -39,8 +39,7 @@ type ObjectHeader struct {
 }
 
 type Scanner struct {
-	r   reader
-	zr  readerResetter
+	r   *scannerReader
 	crc hash.Hash32
 
 	// pendingObject is used to detect if an object has been read, or still
@@ -56,19 +55,27 @@ type Scanner struct {
 // NewScanner returns a new Scanner based on a reader, if the given reader
 // implements io.ReadSeeker the Scanner will be also Seekable
 func NewScanner(r io.Reader) *Scanner {
-	seeker, ok := r.(io.ReadSeeker)
-	if !ok {
-		seeker = &trackableReader{Reader: r}
-	}
+	_, ok := r.(io.ReadSeeker)
 
 	crc := crc32.NewIEEE()
 	return &Scanner{
-		r:          newTeeReader(newByteReadSeeker(seeker), crc),
+		r:          newScannerReader(r, crc),
 		crc:        crc,
 		IsSeekable: ok,
 	}
 }
 
+func (s *Scanner) Reset(r io.Reader) {
+	_, ok := r.(io.ReadSeeker)
+
+	s.r.Reset(r)
+	s.crc.Reset()
+	s.IsSeekable = ok
+	s.pendingObject = nil
+	s.version = 0
+	s.objects = 0
+}
+
 // Header reads the whole packfile header (signature, version and object count).
 // It returns the version and the object count and performs checks on the
 // validity of the signature and the version fields.
@@ -182,8 +189,7 @@ func (s *Scanner) NextObjectHeader() (*ObjectHeader, error) {
 // nextObjectHeader returns the ObjectHeader for the next object in the reader
 // without the Offset field
 func (s *Scanner) nextObjectHeader() (*ObjectHeader, error) {
-	defer s.Flush()
-
+	s.r.Flush()
 	s.crc.Reset()
 
 	h := &ObjectHeader{}
@@ -304,35 +310,29 @@ func (s *Scanner) readLength(first byte) (int64, error) {
 // NextObject writes the content of the next object into the reader, returns
 // the number of bytes written, the CRC32 of the content and an error, if any
 func (s *Scanner) NextObject(w io.Writer) (written int64, crc32 uint32, err error) {
-	defer s.crc.Reset()
-
 	s.pendingObject = nil
 	written, err = s.copyObject(w)
-	s.Flush()
+
+	s.r.Flush()
 	crc32 = s.crc.Sum32()
+	s.crc.Reset()
+
 	return
 }
 
 // ReadRegularObject reads and write a non-deltified object
 // from it zlib stream in an object entry in the packfile.
 func (s *Scanner) copyObject(w io.Writer) (n int64, err error) {
-	if s.zr == nil {
-		var zr io.ReadCloser
-		zr, err = zlib.NewReader(s.r)
-		if err != nil {
-			return 0, fmt.Errorf("zlib initialization error: %s", err)
-		}
+	zr := zlibReaderPool.Get().(io.ReadCloser)
+	defer zlibReaderPool.Put(zr)
 
-		s.zr = zr.(readerResetter)
-	} else {
-		if err = s.zr.Reset(s.r, nil); err != nil {
-			return 0, fmt.Errorf("zlib reset error: %s", err)
-		}
+	if err = zr.(zlib.Resetter).Reset(s.r, nil); err != nil {
+		return 0, fmt.Errorf("zlib reset error: %s", err)
 	}
 
-	defer ioutil.CheckClose(s.zr, &err)
+	defer ioutil.CheckClose(zr, &err)
 	buf := byteSlicePool.Get().([]byte)
-	n, err = io.CopyBuffer(w, s.zr, buf)
+	n, err = io.CopyBuffer(w, zr, buf)
 	byteSlicePool.Put(buf)
 	return
 }
@@ -378,110 +378,89 @@ func (s *Scanner) Close() error {
 	return err
 }
 
-// Flush finishes writing the buffer to crc hasher in case we are using
-// a teeReader. Otherwise it is a no-op.
+// Flush is a no-op (deprecated)
 func (s *Scanner) Flush() error {
-	tee, ok := s.r.(*teeReader)
-	if ok {
-		return tee.Flush()
-	}
 	return nil
 }
 
-type trackableReader struct {
-	count int64
-	io.Reader
+// scannerReader has the following characteristics:
+// - Provides an io.SeekReader impl for bufio.Reader, when the underlying
+//   reader supports it.
+// - Keeps track of the current read position, for when the underlying reader
+//   isn't an io.SeekReader, but we still want to know the current offset.
+// - Writes to the hash writer what it reads, with the aid of a smaller buffer.
+//   The buffer helps avoid a performance penality for performing small writes
+//   to the crc32 hash writer.
+type scannerReader struct {
+	reader io.Reader
+	crc    io.Writer
+	rbuf   *bufio.Reader
+	wbuf   *bufio.Writer
+	offset int64
 }
 
-// Read reads up to len(p) bytes into p.
-func (r *trackableReader) Read(p []byte) (n int, err error) {
-	n, err = r.Reader.Read(p)
-	r.count += int64(n)
-
-	return
-}
-
-// Seek only supports io.SeekCurrent, any other operation fails
-func (r *trackableReader) Seek(offset int64, whence int) (int64, error) {
-	if whence != io.SeekCurrent {
-		return -1, ErrSeekNotSupported
+func newScannerReader(r io.Reader, h io.Writer) *scannerReader {
+	sr := &scannerReader{
+		rbuf: bufio.NewReader(nil),
+		wbuf: bufio.NewWriterSize(nil, 64),
+		crc:  h,
 	}
+	sr.Reset(r)
 
-	return r.count, nil
+	return sr
 }
 
-func newByteReadSeeker(r io.ReadSeeker) *bufferedSeeker {
-	return &bufferedSeeker{
-		r:      r,
-		Reader: *bufio.NewReader(r),
+func (r *scannerReader) Reset(reader io.Reader) {
+	r.reader = reader
+	r.rbuf.Reset(r.reader)
+	r.wbuf.Reset(r.crc)
+
+	r.offset = 0
+	if seeker, ok := r.reader.(io.ReadSeeker); ok {
+		r.offset, _ = seeker.Seek(0, io.SeekCurrent)
 	}
 }
 
-type bufferedSeeker struct {
-	r io.ReadSeeker
-	bufio.Reader
-}
+func (r *scannerReader) Read(p []byte) (n int, err error) {
+	n, err = r.rbuf.Read(p)
 
-func (r *bufferedSeeker) Seek(offset int64, whence int) (int64, error) {
-	if whence == io.SeekCurrent && offset == 0 {
-		current, err := r.r.Seek(offset, whence)
-		if err != nil {
-			return current, err
-		}
-
-		return current - int64(r.Buffered()), nil
-	}
-
-	defer r.Reader.Reset(r.r)
-	return r.r.Seek(offset, whence)
-}
-
-type readerResetter interface {
-	io.ReadCloser
-	zlib.Resetter
-}
-
-type reader interface {
-	io.Reader
-	io.ByteReader
-	io.Seeker
-}
-
-type teeReader struct {
-	reader
-	w         hash.Hash32
-	bufWriter *bufio.Writer
-}
-
-func newTeeReader(r reader, h hash.Hash32) *teeReader {
-	return &teeReader{
-		reader:    r,
-		w:         h,
-		bufWriter: bufio.NewWriter(h),
-	}
-}
-
-func (r *teeReader) Read(p []byte) (n int, err error) {
-	r.Flush()
-
-	n, err = r.reader.Read(p)
-	if n > 0 {
-		if n, err := r.w.Write(p[:n]); err != nil {
-			return n, err
-		}
+	r.offset += int64(n)
+	if _, err := r.wbuf.Write(p[:n]); err != nil {
+		return n, err
 	}
 	return
 }
 
-func (r *teeReader) ReadByte() (b byte, err error) {
-	b, err = r.reader.ReadByte()
+func (r *scannerReader) ReadByte() (b byte, err error) {
+	b, err = r.rbuf.ReadByte()
 	if err == nil {
-		return b, r.bufWriter.WriteByte(b)
+		r.offset++
+		return b, r.wbuf.WriteByte(b)
 	}
-
 	return
 }
 
-func (r *teeReader) Flush() (err error) {
-	return r.bufWriter.Flush()
+func (r *scannerReader) Flush() error {
+	return r.wbuf.Flush()
+}
+
+// Seek seeks to a location. If the underlying reader is not an io.ReadSeeker,
+// then only whence=io.SeekCurrent is supported, any other operation fails.
+func (r *scannerReader) Seek(offset int64, whence int) (int64, error) {
+	var err error
+
+	if seeker, ok := r.reader.(io.ReadSeeker); !ok {
+		if whence != io.SeekCurrent || offset != 0 {
+			return -1, ErrSeekNotSupported
+		}
+	} else {
+		if whence == io.SeekCurrent && offset == 0 {
+			return r.offset, nil
+		}
+
+		r.offset, err = seeker.Seek(offset, whence)
+		r.rbuf.Reset(r.reader)
+	}
+
+	return r.offset, err
 }