// https://github.com/git/git/blob/master/Documentation/gitrepository-layout.txt
package dotgit
import (
"crypto/sha1"
"errors"
"fmt"
"io"
"os"
"strings"
"time"
"gopkg.in/src-d/go-git.v4/core"
"gopkg.in/src-d/go-git.v4/formats/idxfile"
"gopkg.in/src-d/go-git.v4/formats/packfile"
"gopkg.in/src-d/go-git.v4/storage/memory"
"gopkg.in/src-d/go-git.v4/utils/fs"
)
const (
suffix = ".git"
packedRefsPath = "packed-refs"
configPath = "config"
objectsPath = "objects"
packPath = "pack"
packExt = ".pack"
idxExt = ".idx"
)
var (
// ErrNotFound is returned by New when the path is not found.
ErrNotFound = errors.New("path not found")
// ErrIdxNotFound is returned by Idxfile when the idx file is not found
ErrIdxNotFound = errors.New("idx file not found")
// ErrPackfileNotFound is returned by Packfile when the packfile is not found
ErrPackfileNotFound = errors.New("packfile not found")
// ErrConfigNotFound is returned by Config when the config is not found
ErrConfigNotFound = errors.New("config file not found")
)
// The DotGit type represents a local git repository on disk. This
// type is not zero-value-safe, use the New function to initialize it.
type DotGit struct {
fs fs.Filesystem
}
// New returns a DotGit value ready to be used. The path argument must
// be the absolute path of a git repository directory (e.g.
// "/foo/bar/.git").
func New(fs fs.Filesystem) *DotGit {
return &DotGit{fs: fs}
}
// Config returns the path of the config file
func (d *DotGit) Config() (fs.File, error) {
return d.fs.Open(configPath)
}
// Refs scans the git directory collecting references, which it returns.
// Symbolic references are resolved and included in the output.
func (d *DotGit) Refs() ([]*core.Reference, error) {
var refs []*core.Reference
if err := d.addRefsFromPackedRefs(&refs); err != nil {
return nil, err
}
if err := d.addRefsFromRefDir(&refs); err != nil {
return nil, err
}
if err := d.addRefFromHEAD(&refs); err != nil {
return nil, err
}
return refs, nil
}
// NewObjectPack return a writer for a new packfile, it saves the packfile to
// disk and also generates and save the index for the given packfile.
func (d *DotGit) NewObjectPack() (*PackWriter, error) {
return newPackWrite(d.fs)
}
// ObjectPacks returns the list of availables packfiles
func (d *DotGit) ObjectPacks() ([]core.Hash, error) {
packDir := d.fs.Join(objectsPath, packPath)
files, err := d.fs.ReadDir(packDir)
if err != nil {
if os.IsNotExist(err) {
return nil, nil
}
return nil, err
}
var packs []core.Hash
for _, f := range files {
if !strings.HasSuffix(f.Name(), packExt) {
continue
}
n := f.Name()
h := core.NewHash(n[5 : len(n)-5]) //pack-(hash).pack
packs = append(packs, h)
}
return packs, nil
}
// ObjectPack returns a fs.File of the given packfile
func (d *DotGit) ObjectPack(hash core.Hash) (fs.File, error) {
file := d.fs.Join(objectsPath, packPath, fmt.Sprintf("pack-%s.pack", hash.String()))
pack, err := d.fs.Open(file)
if err != nil {
if os.IsNotExist(err) {
return nil, ErrPackfileNotFound
}
return nil, err
}
return pack, nil
}
// ObjectPackIdx returns a fs.File of the index file for a given packfile
func (d *DotGit) ObjectPackIdx(hash core.Hash) (fs.File, error) {
file := d.fs.Join(objectsPath, packPath, fmt.Sprintf("pack-%s.idx", hash.String()))
idx, err := d.fs.Open(file)
if err != nil {
if os.IsNotExist(err) {
return nil, ErrPackfileNotFound
}
return nil, err
}
return idx, nil
}
// Objects returns a slice with the hashes of objects found under the
// .git/objects/ directory.
func (d *DotGit) Objects() ([]core.Hash, error) {
files, err := d.fs.ReadDir(objectsPath)
if err != nil {
if os.IsNotExist(err) {
return nil, nil
}
return nil, err
}
var objects []core.Hash
for _, f := range files {
if f.IsDir() && len(f.Name()) == 2 && isHex(f.Name()) {
base := f.Name()
d, err := d.fs.ReadDir(d.fs.Join(objectsPath, base))
if err != nil {
return nil, err
}
for _, o := range d {
objects = append(objects, core.NewHash(base+o.Name()))
}
}
}
return objects, nil
}
// Object return a fs.File poiting the object file, if exists
func (d *DotGit) Object(h core.Hash) (fs.File, error) {
hash := h.String()
file := d.fs.Join(objectsPath, hash[0:2], hash[2:40])
return d.fs.Open(file)
}
func isHex(s string) bool {
for _, b := range []byte(s) {
if isNum(b) {
continue
}
if isHexAlpha(b) {
continue
}
return false
}
return true
}
func isNum(b byte) bool {
return b >= '0' && b <= '9'
}
func isHexAlpha(b byte) bool {
return b >= 'a' && b <= 'f' || b >= 'A' && b <= 'F'
}
type PackWriter struct {
fs fs.Filesystem
sr io.ReadCloser
sw io.WriteCloser
fw fs.File
mw io.Writer
checksum core.Hash
index idxfile.Idxfile
result chan error
}
func newPackWrite(fs fs.Filesystem) (*PackWriter, error) {
temp := sha1.Sum([]byte(time.Now().String()))
filename := fmt.Sprintf(".%x", temp)
fw, err := fs.Create(fs.Join(objectsPath, packPath, filename))
if err != nil {
return nil, err
}
sr, sw := io.Pipe()
writer := &PackWriter{
fs: fs,
fw: fw,
sr: sr,
sw: sw,
mw: io.MultiWriter(sw, fw),
result: make(chan error),
}
go writer.buildIndex()
return writer, nil
}
func (w *PackWriter) buildIndex() {
defer w.sr.Close()
o := memory.NewStorage().ObjectStorage()
s := packfile.NewScannerFromReader(w.sr)
d := packfile.NewDecoder(s, o)
checksum, err := d.Decode()
if err != nil {
w.result <- err
return
}
w.checksum = checksum
w.index.PackfileChecksum = checksum
offsets := d.Offsets()
for h, crc := range d.CRCs() {
w.index.Add(h, uint64(offsets[h]), crc)
}
w.result <- err
}
func (w *PackWriter) Write(p []byte) (int, error) {
return w.mw.Write(p)
}
func (w *PackWriter) Close() error {
defer func() {
close(w.result)
}()
if err := w.fw.Close(); err != nil {
return err
}
if err := w.sw.Close(); err != nil {
return err
}
if err := <-w.result; err != nil {
return err
}
return w.save()
}
func (w *PackWriter) save() error {
base := w.fs.Join(objectsPath, packPath, fmt.Sprintf("pack-%s", w.checksum))
idx, err := w.fs.Create(fmt.Sprintf("%s.idx", base))
if err != nil {
return err
}
if err := w.encodeIdx(idx); err != nil {
return err
}
if err := idx.Close(); err != nil {
return err
}
return w.fs.Rename(w.fw.Filename(), fmt.Sprintf("%s.pack", base))
}
func (w *PackWriter) encodeIdx(writer io.Writer) error {
e := idxfile.NewEncoder(writer)
_, err := e.Encode(&w.index)
return err
}
