package packfile
import (
"bytes"
"io"
"os"
billy "github.com/go-git/go-billy/v5"
"github.com/go-git/go-git/v5/plumbing"
"github.com/go-git/go-git/v5/plumbing/cache"
"github.com/go-git/go-git/v5/plumbing/format/idxfile"
"github.com/go-git/go-git/v5/plumbing/storer"
"github.com/go-git/go-git/v5/utils/ioutil"
)
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")
)
// When reading small objects from packfile it is beneficial to do so at
// once to exploit the buffered I/O. In many cases the objects are so small
// that they were already loaded to memory when the object header was
// loaded from the packfile. Wrapping in FSObject would cause this buffered
// data to be thrown away and then re-read later, with the additional
// seeking causing reloads from disk. Objects smaller than this threshold
// are now always read into memory and stored in cache instead of being
// wrapped in FSObject.
const smallObjectThreshold = 16 * 1024
// 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.objectAtOffset(offset, h)
}
// 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 {
return nil, err
}
return p.objectAtOffset(o, hash)
}
// GetSizeByOffset retrieves the size of the encoded object from the
// packfile with the given offset.
func (p *Packfile) GetSizeByOffset(o int64) (size int64, err error) {
if _, err := p.s.SeekFromStart(o); err != nil {
if err == io.EOF || isInvalid(err) {
return 0, plumbing.ErrObjectNotFound
}
return 0, err
}
h, err := p.nextObjectHeader()
if err != nil {
return 0, err
}
return p.getObjectSize(h)
}
func (p *Packfile) objectHeaderAtOffset(offset int64) (*ObjectHeader, error) {
h, err := p.s.SeekObjectHeader(offset)
p.s.pendingObject = nil
return h, err
}
func (p *Packfile) nextObjectHeader() (*ObjectHeader, error) {
h, err := p.s.NextObjectHeader()
p.s.pendingObject = nil
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)
defer bufPool.Put(buf)
buf.Reset()
if _, _, err := p.s.NextObject(buf); err != nil {
return 0, err
}
return p.getDeltaObjectSize(buf), 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 {
h, err = p.objectHeaderAtOffset(offset)
if err != nil {
return
}
typ, err = p.getObjectType(h)
if err != nil {
return
}
}
default:
err = ErrInvalidObject.AddDetails("type %q", h.Type)
}
p.offsetToType[h.Offset] = typ
return
}
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) {
return nil, plumbing.ErrObjectNotFound
}
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.getNextMemoryObject(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)
}
// 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 = 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)
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) {
h, err := p.objectHeaderAtOffset(offset)
if err != nil {
return nil, err
}
// 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
}
return obj.Reader()
}
func (p *Packfile) getNextMemoryObject(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
}
p.offsetToType[h.Offset] = obj.Type()
return obj, nil
}
func (p *Packfile) fillRegularObjectContent(obj plumbing.EncodedObject) (err error) {
w, err := obj.Writer()
if err != nil {
return err
}
defer ioutil.CheckClose(w, &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)
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)
if err != nil {
return err
}
}
obj.SetType(base.Type())
err = ApplyDelta(obj, base, buf.Bytes())
p.cachePut(obj)
return err
}
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
}
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 {
return err
}
base, err := p.objectAtOffset(offset, hash)
if err != nil {
return err
}
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
}
// 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)
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
}
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
}
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()
