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package packfile
import (
"bytes"
"io"
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"
)
// Packfile allows retrieving information from inside a packfile.
type Packfile struct {
idxfile.Index
billy.File
s *Scanner
deltaBaseCache cache.Object
offsetToHash map[int64]plumbing.Hash
}
// NewPackfile returns a packfile representation for the given packfile file
// and packfile idx.
func NewPackfile(index idxfile.Index, file billy.File) *Packfile {
s := NewScanner(file)
return &Packfile{
index,
file,
s,
cache.NewObjectLRUDefault(),
make(map[int64]plumbing.Hash),
}
}
// 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) {
if h, ok := p.offsetToHash[o]; ok {
if obj, ok := p.deltaBaseCache.Get(h); ok {
return obj, nil
}
}
if _, err := p.s.SeekFromStart(o); err != nil {
return nil, err
}
return p.nextObject()
}
func (p *Packfile) nextObject() (plumbing.EncodedObject, error) {
h, err := p.s.NextObjectHeader()
if err != nil {
return nil, err
}
obj := new(plumbing.MemoryObject)
obj.SetSize(h.Length)
obj.SetType(h.Type)
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 obj, err
}
p.offsetToHash[h.Offset] = obj.Hash()
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)
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
h, ok := p.offsetToHash[offset]
if ok {
base, ok = p.cacheGet(h)
}
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) {
s := NewScanner(p.File)
_, count, err := s.Header()
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.
d: &Packfile{p.Index, nil, s, p.deltaBaseCache, p.offsetToHash},
count: int(count),
}, nil
}
// ID returns the ID of the packfile, which is the checksum at the end of it.
func (p *Packfile) ID() (plumbing.Hash, error) {
if _, err := p.File.Seek(-20, io.SeekEnd); err != nil {
return plumbing.ZeroHash, err
}
var hash plumbing.Hash
if _, err := io.ReadFull(p.File, hash[:]); err != nil {
return plumbing.ZeroHash, err
}
return hash, nil
}
// Close the packfile and its resources.
func (p *Packfile) Close() error {
return p.File.Close()
}
type objectDecoder interface {
nextObject() (plumbing.EncodedObject, error)
}
type objectIter struct {
d objectDecoder
count int
pos int
}
func (i *objectIter) Next() (plumbing.EncodedObject, error) {
if i.pos >= i.count {
return nil, io.EOF
}
i.pos++
return i.d.nextObject()
}
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.pos = i.count
}
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