1 files changed, 97 insertions, 8 deletions

diff --git a/storage/filesystem/object.go b/storage/filesystem/object.go
index 9eb085f..6cd2d4c 100644
--- a/storage/filesystem/object.go
+++ b/storage/filesystem/object.go
@@ -160,6 +160,79 @@ func (s *ObjectStorage) HasEncodedObject(h plumbing.Hash) (err error) {
 	return nil
 }
 
+func (s *ObjectStorage) encodedObjectSizeFromUnpacked(h plumbing.Hash) (
+	size int64, err error) {
+	f, err := s.dir.Object(h)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return 0, plumbing.ErrObjectNotFound
+		}
+
+		return 0, err
+	}
+
+	r, err := objfile.NewReader(f)
+	if err != nil {
+		return 0, err
+	}
+	defer ioutil.CheckClose(r, &err)
+
+	_, size, err = r.Header()
+	return size, err
+}
+
+func (s *ObjectStorage) encodedObjectSizeFromPackfile(h plumbing.Hash) (
+	size int64, err error) {
+	if err := s.requireIndex(); err != nil {
+		return 0, err
+	}
+
+	pack, _, offset := s.findObjectInPackfile(h)
+	if offset == -1 {
+		return 0, plumbing.ErrObjectNotFound
+	}
+
+	f, err := s.dir.ObjectPack(pack)
+	if err != nil {
+		return 0, err
+	}
+	defer ioutil.CheckClose(f, &err)
+
+	idx := s.index[pack]
+	hash, err := idx.FindHash(offset)
+	if err == nil {
+		obj, ok := s.deltaBaseCache.Get(hash)
+		if ok {
+			return obj.Size(), nil
+		}
+	} else if err != nil && err != plumbing.ErrObjectNotFound {
+		return 0, err
+	}
+
+	var p *packfile.Packfile
+	if s.deltaBaseCache != nil {
+		p = packfile.NewPackfileWithCache(idx, s.dir.Fs(), f, s.deltaBaseCache)
+	} else {
+		p = packfile.NewPackfile(idx, s.dir.Fs(), f)
+	}
+
+	return p.GetSizeByOffset(offset)
+}
+
+// EncodedObjectSize returns the plaintext size of the given object,
+// without actually reading the full object data from storage.
+func (s *ObjectStorage) EncodedObjectSize(h plumbing.Hash) (
+	size int64, err error) {
+	size, err = s.encodedObjectSizeFromUnpacked(h)
+	if err != nil && err != plumbing.ErrObjectNotFound {
+		return 0, err
+	} else if err == nil {
+		return size, nil
+	}
+
+	return s.encodedObjectSizeFromPackfile(h)
+}
+
 // EncodedObject returns the object with the given hash, by searching for it in
 // the packfile and the git object directories.
 func (s *ObjectStorage) EncodedObject(t plumbing.ObjectType, h plumbing.Hash) (plumbing.EncodedObject, error) {
@@ -396,7 +469,10 @@ func (s *ObjectStorage) IterEncodedObjects(t plumbing.ObjectType) (storer.Encode
 	return storer.NewMultiEncodedObjectIter(iters), nil
 }
 
-func (s *ObjectStorage) buildPackfileIters(t plumbing.ObjectType, seen map[plumbing.Hash]struct{}) (storer.EncodedObjectIter, error) {
+func (s *ObjectStorage) buildPackfileIters(
+	t plumbing.ObjectType,
+	seen map[plumbing.Hash]struct{},
+) (storer.EncodedObjectIter, error) {
 	if err := s.requireIndex(); err != nil {
 		return nil, err
 	}
@@ -412,7 +488,10 @@ func (s *ObjectStorage) buildPackfileIters(t plumbing.ObjectType, seen map[plumb
 			if err != nil {
 				return nil, err
 			}
-			return newPackfileIter(s.dir.Fs(), pack, t, seen, s.index[h], s.deltaBaseCache)
+			return newPackfileIter(
+				s.dir.Fs(), pack, t, seen, s.index[h],
+				s.deltaBaseCache, s.options.KeepDescriptors,
+			)
 		},
 	}, nil
 }
@@ -473,16 +552,21 @@ type packfileIter struct {
 	pack billy.File
 	iter storer.EncodedObjectIter
 	seen map[plumbing.Hash]struct{}
+
+	// tells whether the pack file should be left open after iteration or not
+	keepPack bool
 }
 
 // NewPackfileIter returns a new EncodedObjectIter for the provided packfile
 // and object type. Packfile and index file will be closed after they're
-// used.
+// used. If keepPack is true the packfile won't be closed after the iteration
+// finished.
 func NewPackfileIter(
 	fs billy.Filesystem,
 	f billy.File,
 	idxFile billy.File,
 	t plumbing.ObjectType,
+	keepPack bool,
 ) (storer.EncodedObjectIter, error) {
 	idx := idxfile.NewMemoryIndex()
 	if err := idxfile.NewDecoder(idxFile).Decode(idx); err != nil {
@@ -493,7 +577,8 @@ func NewPackfileIter(
 		return nil, err
 	}
 
-	return newPackfileIter(fs, f, t, make(map[plumbing.Hash]struct{}), idx, nil)
+	seen := make(map[plumbing.Hash]struct{})
+	return newPackfileIter(fs, f, t, seen, idx, nil, keepPack)
 }
 
 func newPackfileIter(
@@ -503,6 +588,7 @@ func newPackfileIter(
 	seen map[plumbing.Hash]struct{},
 	index idxfile.Index,
 	cache cache.Object,
+	keepPack bool,
 ) (storer.EncodedObjectIter, error) {
 	var p *packfile.Packfile
 	if cache != nil {
@@ -517,9 +603,10 @@ func newPackfileIter(
 	}
 
 	return &packfileIter{
-		pack: f,
-		iter: iter,
-		seen: seen,
+		pack:     f,
+		iter:     iter,
+		seen:     seen,
+		keepPack: keepPack,
 	}, nil
 }
 
@@ -557,7 +644,9 @@ func (iter *packfileIter) ForEach(cb func(plumbing.EncodedObject) error) error {
 
 func (iter *packfileIter) Close() {
 	iter.iter.Close()
-	_ = iter.pack.Close()
+	if !iter.keepPack {
+		_ = iter.pack.Close()
+	}
 }
 
 type objectsIter struct {