diff options
Diffstat (limited to 'plumbing/format/packfile/packfile.go')
| -rw-r--r-- | plumbing/format/packfile/packfile.go | 520 |
1 files changed, 520 insertions, 0 deletions
diff --git a/plumbing/format/packfile/packfile.go b/plumbing/format/packfile/packfile.go new file mode 100644 index 0000000..852a834 --- /dev/null +++ b/plumbing/format/packfile/packfile.go @@ -0,0 +1,520 @@ +package packfile + +import ( + "bytes" + "io" + "os" + + billy "gopkg.in/src-d/go-billy.v4" + "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/storer" +) + +var ( + // ErrInvalidObject is returned by Decode when an invalid object is + // found in the packfile. + ErrInvalidObject = NewError("invalid git object") + // ErrZLib is returned by Decode when there was an error unzipping + // the packfile contents. + ErrZLib = NewError("zlib reading error") +) + +// Packfile allows retrieving information from inside a packfile. +type Packfile struct { + idxfile.Index + fs billy.Filesystem + file billy.File + s *Scanner + deltaBaseCache cache.Object + offsetToType map[int64]plumbing.ObjectType +} + +// NewPackfileWithCache creates a new Packfile with the given object cache. +// If the filesystem is provided, the packfile will return FSObjects, otherwise +// it will return MemoryObjects. +func NewPackfileWithCache( + index idxfile.Index, + fs billy.Filesystem, + file billy.File, + cache cache.Object, +) *Packfile { + s := NewScanner(file) + return &Packfile{ + index, + fs, + file, + s, + cache, + make(map[int64]plumbing.ObjectType), + } +} + +// NewPackfile returns a packfile representation for the given packfile file +// and packfile idx. +// If the filesystem is provided, the packfile will return FSObjects, otherwise +// it will return MemoryObjects. +func NewPackfile(index idxfile.Index, fs billy.Filesystem, file billy.File) *Packfile { + return NewPackfileWithCache(index, fs, file, cache.NewObjectLRUDefault()) +} + +// Get retrieves the encoded object in the packfile with the given hash. +func (p *Packfile) Get(h plumbing.Hash) (plumbing.EncodedObject, error) { + offset, err := p.FindOffset(h) + if err != nil { + return nil, err + } + + return p.GetByOffset(offset) +} + +// GetByOffset retrieves the encoded object from the packfile with 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 := p.s.SeekFromStart(o); err != nil { + if err == io.EOF || isInvalid(err) { + return nil, plumbing.ErrObjectNotFound + } + + return nil, err + } + + return p.nextObject() +} + +func (p *Packfile) nextObjectHeader() (*ObjectHeader, error) { + h, err := p.s.NextObjectHeader() + p.s.pendingObject = nil + return h, err +} + +func (p *Packfile) getObjectData( + h *ObjectHeader, +) (typ plumbing.ObjectType, size int64, err error) { + switch h.Type { + case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject: + typ = h.Type + size = h.Length + case plumbing.REFDeltaObject, plumbing.OFSDeltaObject: + buf := bufPool.Get().(*bytes.Buffer) + buf.Reset() + defer bufPool.Put(buf) + + _, _, err = p.s.NextObject(buf) + if err != nil { + return + } + + delta := buf.Bytes() + _, delta = decodeLEB128(delta) // skip src size + sz, _ := decodeLEB128(delta) + size = int64(sz) + + var offset int64 + if h.Type == plumbing.REFDeltaObject { + offset, err = p.FindOffset(h.Reference) + if err != nil { + return + } + } else { + offset = h.OffsetReference + } + + if baseType, ok := p.offsetToType[offset]; ok { + typ = baseType + } else { + if _, err = p.s.SeekFromStart(offset); err != nil { + return + } + + h, err = p.nextObjectHeader() + if err != nil { + return + } + + typ, _, err = p.getObjectData(h) + if err != nil { + return + } + } + default: + err = ErrInvalidObject.AddDetails("type %q", h.Type) + } + + return +} + +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) + + 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 + default: + return 0, ErrInvalidObject.AddDetails("type %q", h.Type) + } +} + +func (p *Packfile) getObjectType(h *ObjectHeader) (typ plumbing.ObjectType, err error) { + switch h.Type { + case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject: + return h.Type, nil + case plumbing.REFDeltaObject, plumbing.OFSDeltaObject: + var offset int64 + if h.Type == plumbing.REFDeltaObject { + offset, err = p.FindOffset(h.Reference) + if err != nil { + return + } + } else { + offset = h.OffsetReference + } + + if baseType, ok := p.offsetToType[offset]; ok { + typ = baseType + } else { + if _, err = p.s.SeekFromStart(offset); err != nil { + return + } + + h, err = p.nextObjectHeader() + if err != nil { + return + } + + typ, err = p.getObjectType(h) + if err != nil { + return + } + } + default: + err = ErrInvalidObject.AddDetails("type %q", h.Type) + } + + return +} + +func (p *Packfile) nextObject() (plumbing.EncodedObject, error) { + h, err := p.nextObjectHeader() + if err != nil { + if err == io.EOF || isInvalid(err) { + return nil, plumbing.ErrObjectNotFound + } + return nil, err + } + + // If we have no filesystem, we will return a MemoryObject instead + // of an FSObject. + if p.fs == nil { + return p.getNextObject(h) + } + + hash, err := p.FindHash(h.Offset) + if err != nil { + return nil, err + } + + size, err := p.getObjectSize(h) + if err != nil { + return nil, err + } + + typ, err := p.getObjectType(h) + if err != nil { + return nil, err + } + + p.offsetToType[h.Offset] = typ + + return NewFSObject( + hash, + typ, + h.Offset, + size, + p.Index, + p.fs, + p.file.Name(), + p.deltaBaseCache, + ), nil +} + +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 + } + } + + if _, err := p.s.SeekFromStart(offset); err != nil { + return nil, err + } + + h, err := p.nextObjectHeader() + if err != nil { + return nil, err + } + + obj, err := p.getNextObject(h) + if err != nil { + return nil, err + } + + return obj.Reader() +} + +func (p *Packfile) getNextObject(h *ObjectHeader) (plumbing.EncodedObject, error) { + var obj = new(plumbing.MemoryObject) + obj.SetSize(h.Length) + obj.SetType(h.Type) + + var err error + switch h.Type { + case plumbing.CommitObject, plumbing.TreeObject, plumbing.BlobObject, plumbing.TagObject: + err = p.fillRegularObjectContent(obj) + case plumbing.REFDeltaObject: + err = p.fillREFDeltaObjectContent(obj, h.Reference) + case plumbing.OFSDeltaObject: + err = p.fillOFSDeltaObjectContent(obj, h.OffsetReference) + default: + err = ErrInvalidObject.AddDetails("type %q", h.Type) + } + + if err != nil { + return nil, err + } + + return obj, nil +} + +func (p *Packfile) fillRegularObjectContent(obj plumbing.EncodedObject) error { + w, err := obj.Writer() + if err != nil { + return err + } + + _, _, err = p.s.NextObject(w) + p.cachePut(obj) + + return err +} + +func (p *Packfile) fillREFDeltaObjectContent(obj plumbing.EncodedObject, ref plumbing.Hash) error { + buf := bufPool.Get().(*bytes.Buffer) + buf.Reset() + _, _, err := p.s.NextObject(buf) + if err != nil { + return err + } + + base, ok := p.cacheGet(ref) + if !ok { + base, err = p.Get(ref) + if err != nil { + return err + } + } + + 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) + _, _, err := p.s.NextObject(buf) + if err != nil { + return err + } + + var base plumbing.EncodedObject + var ok bool + hash, err := p.FindHash(offset) + if err == nil { + base, ok = p.cacheGet(hash) + } + + if !ok { + base, err = p.GetByOffset(offset) + if err != nil { + return err + } + + p.cachePut(base) + } + + obj.SetType(base.Type()) + err = ApplyDelta(obj, base, buf.Bytes()) + p.cachePut(obj) + + return err +} + +func (p *Packfile) cacheGet(h plumbing.Hash) (plumbing.EncodedObject, bool) { + if p.deltaBaseCache == nil { + return nil, false + } + + return p.deltaBaseCache.Get(h) +} + +func (p *Packfile) cachePut(obj plumbing.EncodedObject) { + if p.deltaBaseCache == nil { + return + } + + p.deltaBaseCache.Put(obj) +} + +// GetAll returns an iterator with all encoded objects in the packfile. +// The iterator returned is not thread-safe, it should be used in the same +// thread as the Packfile instance. +func (p *Packfile) GetAll() (storer.EncodedObjectIter, error) { + return p.GetByType(plumbing.AnyObject) +} + +// GetByType returns all the objects of the given type. +func (p *Packfile) GetByType(typ plumbing.ObjectType) (storer.EncodedObjectIter, error) { + switch typ { + case plumbing.AnyObject, + plumbing.BlobObject, + plumbing.TreeObject, + plumbing.CommitObject, + plumbing.TagObject: + entries, err := p.EntriesByOffset() + if err != nil { + return nil, err + } + + return &objectIter{ + // Easiest way to provide an object decoder is just to pass a Packfile + // instance. To not mess with the seeks, it's a new instance with a + // different scanner but the same cache and offset to hash map for + // reusing as much cache as possible. + p: p, + iter: entries, + typ: typ, + }, nil + default: + return nil, plumbing.ErrInvalidType + } +} + +// ID returns the ID of the packfile, which is the checksum at the end of it. +func (p *Packfile) ID() (plumbing.Hash, error) { + prev, err := p.file.Seek(-20, io.SeekEnd) + if err != nil { + return plumbing.ZeroHash, err + } + + var hash plumbing.Hash + if _, err := io.ReadFull(p.file, hash[:]); err != nil { + return plumbing.ZeroHash, err + } + + if _, err := p.file.Seek(prev, io.SeekStart); err != nil { + return plumbing.ZeroHash, err + } + + return hash, nil +} + +// Close the packfile and its resources. +func (p *Packfile) Close() error { + closer, ok := p.file.(io.Closer) + if !ok { + return nil + } + + return closer.Close() +} + +type objectIter struct { + p *Packfile + typ plumbing.ObjectType + iter idxfile.EntryIter +} + +func (i *objectIter) Next() (plumbing.EncodedObject, error) { + for { + e, err := i.iter.Next() + if err != nil { + return nil, err + } + + obj, err := i.p.GetByOffset(int64(e.Offset)) + if err != nil { + return nil, err + } + + if i.typ == plumbing.AnyObject || obj.Type() == i.typ { + return obj, nil + } + } +} + +func (i *objectIter) ForEach(f func(plumbing.EncodedObject) error) error { + for { + o, err := i.Next() + if err != nil { + if err == io.EOF { + return nil + } + return err + } + + if err := f(o); err != nil { + return err + } + } +} + +func (i *objectIter) Close() { + i.iter.Close() +} + +// isInvalid checks whether an error is an os.PathError with an os.ErrInvalid +// error inside. It also checks for the windows error, which is different from +// os.ErrInvalid. +func isInvalid(err error) bool { + pe, ok := err.(*os.PathError) + if !ok { + return false + } + + errstr := pe.Err.Error() + return errstr == errInvalidUnix || errstr == errInvalidWindows +} + +// errInvalidWindows is the Windows equivalent to os.ErrInvalid +const errInvalidWindows = "The parameter is incorrect." + +var errInvalidUnix = os.ErrInvalid.Error() |