Implement git refs API for listing references (branches, tags and other) (#5354)

* Inital routes to git refs api

* Git refs API implementation

* Update swagger

* Fix copyright

* Make swagger happy add basic test

* Fix test

* Fix test again :)

vendor/gopkg.in/src-d/go-git.v4/storage/filesystem/object.go

@@ -0,0 +1,736 @@
+package filesystem
+
+import (
+	"io"
+	"os"
+	"time"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/cache"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/idxfile"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/objfile"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/packfile"
+	"gopkg.in/src-d/go-git.v4/plumbing/storer"
+	"gopkg.in/src-d/go-git.v4/storage/filesystem/dotgit"
+	"gopkg.in/src-d/go-git.v4/utils/ioutil"
+
+	"gopkg.in/src-d/go-billy.v4"
+)
+
+type ObjectStorage struct {
+	options Options
+
+	// deltaBaseCache is an object cache uses to cache delta's bases when
+	deltaBaseCache cache.Object
+
+	dir   *dotgit.DotGit
+	index map[plumbing.Hash]idxfile.Index
+}
+
+// NewObjectStorage creates a new ObjectStorage with the given .git directory and cache.
+func NewObjectStorage(dir *dotgit.DotGit, cache cache.Object) *ObjectStorage {
+	return NewObjectStorageWithOptions(dir, cache, Options{})
+}
+
+// NewObjectStorageWithOptions creates a new ObjectStorage with the given .git directory, cache and extra options
+func NewObjectStorageWithOptions(dir *dotgit.DotGit, cache cache.Object, ops Options) *ObjectStorage {
+	return &ObjectStorage{
+		options:        ops,
+		deltaBaseCache: cache,
+		dir:            dir,
+	}
+}
+
+func (s *ObjectStorage) requireIndex() error {
+	if s.index != nil {
+		return nil
+	}
+
+	s.index = make(map[plumbing.Hash]idxfile.Index)
+	packs, err := s.dir.ObjectPacks()
+	if err != nil {
+		return err
+	}
+
+	for _, h := range packs {
+		if err := s.loadIdxFile(h); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Reindex indexes again all packfiles. Useful if git changed packfiles externally
+func (s *ObjectStorage) Reindex() {
+	s.index = nil
+}
+
+func (s *ObjectStorage) loadIdxFile(h plumbing.Hash) (err error) {
+	f, err := s.dir.ObjectPackIdx(h)
+	if err != nil {
+		return err
+	}
+
+	defer ioutil.CheckClose(f, &err)
+
+	idxf := idxfile.NewMemoryIndex()
+	d := idxfile.NewDecoder(f)
+	if err = d.Decode(idxf); err != nil {
+		return err
+	}
+
+	s.index[h] = idxf
+	return err
+}
+
+func (s *ObjectStorage) NewEncodedObject() plumbing.EncodedObject {
+	return &plumbing.MemoryObject{}
+}
+
+func (s *ObjectStorage) PackfileWriter() (io.WriteCloser, error) {
+	if err := s.requireIndex(); err != nil {
+		return nil, err
+	}
+
+	w, err := s.dir.NewObjectPack()
+	if err != nil {
+		return nil, err
+	}
+
+	w.Notify = func(h plumbing.Hash, writer *idxfile.Writer) {
+		index, err := writer.Index()
+		if err == nil {
+			s.index[h] = index
+		}
+	}
+
+	return w, nil
+}
+
+// SetEncodedObject adds a new object to the storage.
+func (s *ObjectStorage) SetEncodedObject(o plumbing.EncodedObject) (h plumbing.Hash, err error) {
+	if o.Type() == plumbing.OFSDeltaObject || o.Type() == plumbing.REFDeltaObject {
+		return plumbing.ZeroHash, plumbing.ErrInvalidType
+	}
+
+	ow, err := s.dir.NewObject()
+	if err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	defer ioutil.CheckClose(ow, &err)
+
+	or, err := o.Reader()
+	if err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	defer ioutil.CheckClose(or, &err)
+
+	if err = ow.WriteHeader(o.Type(), o.Size()); err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	if _, err = io.Copy(ow, or); err != nil {
+		return plumbing.ZeroHash, err
+	}
+
+	return o.Hash(), err
+}
+
+// HasEncodedObject returns nil if the object exists, without actually
+// reading the object data from storage.
+func (s *ObjectStorage) HasEncodedObject(h plumbing.Hash) (err error) {
+	// Check unpacked objects
+	f, err := s.dir.Object(h)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return err
+		}
+		// Fall through to check packed objects.
+	} else {
+		defer ioutil.CheckClose(f, &err)
+		return nil
+	}
+
+	// Check packed objects.
+	if err := s.requireIndex(); err != nil {
+		return err
+	}
+	_, _, offset := s.findObjectInPackfile(h)
+	if offset == -1 {
+		return plumbing.ErrObjectNotFound
+	}
+	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) {
+	obj, err := s.getFromUnpacked(h)
+	if err == plumbing.ErrObjectNotFound {
+		obj, err = s.getFromPackfile(h, false)
+	}
+
+	// If the error is still object not found, check if it's a shared object
+	// repository.
+	if err == plumbing.ErrObjectNotFound {
+		dotgits, e := s.dir.Alternates()
+		if e == nil {
+			// Create a new object storage with the DotGit(s) and check for the
+			// required hash object. Skip when not found.
+			for _, dg := range dotgits {
+				o := NewObjectStorage(dg, s.deltaBaseCache)
+				enobj, enerr := o.EncodedObject(t, h)
+				if enerr != nil {
+					continue
+				}
+				return enobj, nil
+			}
+		}
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	if plumbing.AnyObject != t && obj.Type() != t {
+		return nil, plumbing.ErrObjectNotFound
+	}
+
+	return obj, nil
+}
+
+// DeltaObject returns the object with the given hash, by searching for
+// it in the packfile and the git object directories.
+func (s *ObjectStorage) DeltaObject(t plumbing.ObjectType,
+	h plumbing.Hash) (plumbing.EncodedObject, error) {
+	obj, err := s.getFromUnpacked(h)
+	if err == plumbing.ErrObjectNotFound {
+		obj, err = s.getFromPackfile(h, true)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	if plumbing.AnyObject != t && obj.Type() != t {
+		return nil, plumbing.ErrObjectNotFound
+	}
+
+	return obj, nil
+}
+
+func (s *ObjectStorage) getFromUnpacked(h plumbing.Hash) (obj plumbing.EncodedObject, err error) {
+	f, err := s.dir.Object(h)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, plumbing.ErrObjectNotFound
+		}
+
+		return nil, err
+	}
+
+	defer ioutil.CheckClose(f, &err)
+
+	obj = s.NewEncodedObject()
+	r, err := objfile.NewReader(f)
+	if err != nil {
+		return nil, err
+	}
+
+	defer ioutil.CheckClose(r, &err)
+
+	t, size, err := r.Header()
+	if err != nil {
+		return nil, err
+	}
+
+	obj.SetType(t)
+	obj.SetSize(size)
+	w, err := obj.Writer()
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = io.Copy(w, r)
+	return obj, err
+}
+
+// Get returns the object with the given hash, by searching for it in
+// the packfile.
+func (s *ObjectStorage) getFromPackfile(h plumbing.Hash, canBeDelta bool) (
+	plumbing.EncodedObject, error) {
+
+	if err := s.requireIndex(); err != nil {
+		return nil, err
+	}
+
+	pack, hash, offset := s.findObjectInPackfile(h)
+	if offset == -1 {
+		return nil, plumbing.ErrObjectNotFound
+	}
+
+	f, err := s.dir.ObjectPack(pack)
+	if err != nil {
+		return nil, err
+	}
+
+	if !s.options.KeepDescriptors {
+		defer ioutil.CheckClose(f, &err)
+	}
+
+	idx := s.index[pack]
+	if canBeDelta {
+		return s.decodeDeltaObjectAt(f, idx, offset, hash)
+	}
+
+	return s.decodeObjectAt(f, idx, offset)
+}
+
+func (s *ObjectStorage) decodeObjectAt(
+	f billy.File,
+	idx idxfile.Index,
+	offset int64,
+) (plumbing.EncodedObject, error) {
+	hash, err := idx.FindHash(offset)
+	if err == nil {
+		obj, ok := s.deltaBaseCache.Get(hash)
+		if ok {
+			return obj, nil
+		}
+	}
+
+	if err != nil && err != plumbing.ErrObjectNotFound {
+		return nil, 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.GetByOffset(offset)
+}
+
+func (s *ObjectStorage) decodeDeltaObjectAt(
+	f billy.File,
+	idx idxfile.Index,
+	offset int64,
+	hash plumbing.Hash,
+) (plumbing.EncodedObject, error) {
+	if _, err := f.Seek(0, io.SeekStart); err != nil {
+		return nil, err
+	}
+
+	p := packfile.NewScanner(f)
+	if _, err := p.SeekFromStart(offset); err != nil {
+		return nil, err
+	}
+
+	header, err := p.NextObjectHeader()
+	if err != nil {
+		return nil, err
+	}
+
+	var (
+		base plumbing.Hash
+	)
+
+	switch header.Type {
+	case plumbing.REFDeltaObject:
+		base = header.Reference
+	case plumbing.OFSDeltaObject:
+		base, err = idx.FindHash(header.OffsetReference)
+		if err != nil {
+			return nil, err
+		}
+	default:
+		return s.decodeObjectAt(f, idx, offset)
+	}
+
+	obj := &plumbing.MemoryObject{}
+	obj.SetType(header.Type)
+	w, err := obj.Writer()
+	if err != nil {
+		return nil, err
+	}
+
+	if _, _, err := p.NextObject(w); err != nil {
+		return nil, err
+	}
+
+	return newDeltaObject(obj, hash, base, header.Length), nil
+}
+
+func (s *ObjectStorage) findObjectInPackfile(h plumbing.Hash) (plumbing.Hash, plumbing.Hash, int64) {
+	for packfile, index := range s.index {
+		offset, err := index.FindOffset(h)
+		if err == nil {
+			return packfile, h, offset
+		}
+	}
+
+	return plumbing.ZeroHash, plumbing.ZeroHash, -1
+}
+
+// IterEncodedObjects returns an iterator for all the objects in the packfile
+// with the given type.
+func (s *ObjectStorage) IterEncodedObjects(t plumbing.ObjectType) (storer.EncodedObjectIter, error) {
+	objects, err := s.dir.Objects()
+	if err != nil {
+		return nil, err
+	}
+
+	seen := make(map[plumbing.Hash]struct{})
+	var iters []storer.EncodedObjectIter
+	if len(objects) != 0 {
+		iters = append(iters, &objectsIter{s: s, t: t, h: objects})
+		seen = hashListAsMap(objects)
+	}
+
+	packi, err := s.buildPackfileIters(t, seen)
+	if err != nil {
+		return nil, err
+	}
+
+	iters = append(iters, packi)
+	return storer.NewMultiEncodedObjectIter(iters), nil
+}
+
+func (s *ObjectStorage) buildPackfileIters(
+	t plumbing.ObjectType,
+	seen map[plumbing.Hash]struct{},
+) (storer.EncodedObjectIter, error) {
+	if err := s.requireIndex(); err != nil {
+		return nil, err
+	}
+
+	packs, err := s.dir.ObjectPacks()
+	if err != nil {
+		return nil, err
+	}
+	return &lazyPackfilesIter{
+		hashes: packs,
+		open: func(h plumbing.Hash) (storer.EncodedObjectIter, error) {
+			pack, err := s.dir.ObjectPack(h)
+			if err != nil {
+				return nil, err
+			}
+			return newPackfileIter(
+				s.dir.Fs(), pack, t, seen, s.index[h],
+				s.deltaBaseCache, s.options.KeepDescriptors,
+			)
+		},
+	}, nil
+}
+
+// Close closes all opened files.
+func (s *ObjectStorage) Close() error {
+	return s.dir.Close()
+}
+
+type lazyPackfilesIter struct {
+	hashes []plumbing.Hash
+	open   func(h plumbing.Hash) (storer.EncodedObjectIter, error)
+	cur    storer.EncodedObjectIter
+}
+
+func (it *lazyPackfilesIter) Next() (plumbing.EncodedObject, error) {
+	for {
+		if it.cur == nil {
+			if len(it.hashes) == 0 {
+				return nil, io.EOF
+			}
+			h := it.hashes[0]
+			it.hashes = it.hashes[1:]
+
+			sub, err := it.open(h)
+			if err == io.EOF {
+				continue
+			} else if err != nil {
+				return nil, err
+			}
+			it.cur = sub
+		}
+		ob, err := it.cur.Next()
+		if err == io.EOF {
+			it.cur.Close()
+			it.cur = nil
+			continue
+		} else if err != nil {
+			return nil, err
+		}
+		return ob, nil
+	}
+}
+
+func (it *lazyPackfilesIter) ForEach(cb func(plumbing.EncodedObject) error) error {
+	return storer.ForEachIterator(it, cb)
+}
+
+func (it *lazyPackfilesIter) Close() {
+	if it.cur != nil {
+		it.cur.Close()
+		it.cur = nil
+	}
+	it.hashes = nil
+}
+
+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. 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 {
+		return nil, err
+	}
+
+	if err := idxFile.Close(); err != nil {
+		return nil, err
+	}
+
+	seen := make(map[plumbing.Hash]struct{})
+	return newPackfileIter(fs, f, t, seen, idx, nil, keepPack)
+}
+
+func newPackfileIter(
+	fs billy.Filesystem,
+	f billy.File,
+	t plumbing.ObjectType,
+	seen map[plumbing.Hash]struct{},
+	index idxfile.Index,
+	cache cache.Object,
+	keepPack bool,
+) (storer.EncodedObjectIter, error) {
+	var p *packfile.Packfile
+	if cache != nil {
+		p = packfile.NewPackfileWithCache(index, fs, f, cache)
+	} else {
+		p = packfile.NewPackfile(index, fs, f)
+	}
+
+	iter, err := p.GetByType(t)
+	if err != nil {
+		return nil, err
+	}
+
+	return &packfileIter{
+		pack:     f,
+		iter:     iter,
+		seen:     seen,
+		keepPack: keepPack,
+	}, nil
+}
+
+func (iter *packfileIter) Next() (plumbing.EncodedObject, error) {
+	for {
+		obj, err := iter.iter.Next()
+		if err != nil {
+			return nil, err
+		}
+
+		if _, ok := iter.seen[obj.Hash()]; ok {
+			continue
+		}
+
+		return obj, nil
+	}
+}
+
+func (iter *packfileIter) ForEach(cb func(plumbing.EncodedObject) error) error {
+	for {
+		o, err := iter.Next()
+		if err != nil {
+			if err == io.EOF {
+				iter.Close()
+				return nil
+			}
+			return err
+		}
+
+		if err := cb(o); err != nil {
+			return err
+		}
+	}
+}
+
+func (iter *packfileIter) Close() {
+	iter.iter.Close()
+	if !iter.keepPack {
+		_ = iter.pack.Close()
+	}
+}
+
+type objectsIter struct {
+	s *ObjectStorage
+	t plumbing.ObjectType
+	h []plumbing.Hash
+}
+
+func (iter *objectsIter) Next() (plumbing.EncodedObject, error) {
+	if len(iter.h) == 0 {
+		return nil, io.EOF
+	}
+
+	obj, err := iter.s.getFromUnpacked(iter.h[0])
+	iter.h = iter.h[1:]
+
+	if err != nil {
+		return nil, err
+	}
+
+	if iter.t != plumbing.AnyObject && iter.t != obj.Type() {
+		return iter.Next()
+	}
+
+	return obj, err
+}
+
+func (iter *objectsIter) ForEach(cb func(plumbing.EncodedObject) error) error {
+	for {
+		o, err := iter.Next()
+		if err != nil {
+			if err == io.EOF {
+				return nil
+			}
+			return err
+		}
+
+		if err := cb(o); err != nil {
+			return err
+		}
+	}
+}
+
+func (iter *objectsIter) Close() {
+	iter.h = []plumbing.Hash{}
+}
+
+func hashListAsMap(l []plumbing.Hash) map[plumbing.Hash]struct{} {
+	m := make(map[plumbing.Hash]struct{}, len(l))
+	for _, h := range l {
+		m[h] = struct{}{}
+	}
+	return m
+}
+
+func (s *ObjectStorage) ForEachObjectHash(fun func(plumbing.Hash) error) error {
+	err := s.dir.ForEachObjectHash(fun)
+	if err == storer.ErrStop {
+		return nil
+	}
+	return err
+}
+
+func (s *ObjectStorage) LooseObjectTime(hash plumbing.Hash) (time.Time, error) {
+	fi, err := s.dir.ObjectStat(hash)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return fi.ModTime(), nil
+}
+
+func (s *ObjectStorage) DeleteLooseObject(hash plumbing.Hash) error {
+	return s.dir.ObjectDelete(hash)
+}
+
+func (s *ObjectStorage) ObjectPacks() ([]plumbing.Hash, error) {
+	return s.dir.ObjectPacks()
+}
+
+func (s *ObjectStorage) DeleteOldObjectPackAndIndex(h plumbing.Hash, t time.Time) error {
+	return s.dir.DeleteOldObjectPackAndIndex(h, t)
+}