// https://github.com/git/git/blob/master/Documentation/gitrepository-layout.txt
package dotgit
import (
"bufio"
"errors"
"fmt"
"io"
stdioutil "io/ioutil"
"os"
"path/filepath"
"strings"
"time"
"gopkg.in/src-d/go-billy.v4/osfs"
"gopkg.in/src-d/go-git.v4/plumbing"
"gopkg.in/src-d/go-git.v4/utils/ioutil"
"gopkg.in/src-d/go-billy.v4"
)
const (
suffix = ".git"
packedRefsPath = "packed-refs"
configPath = "config"
indexPath = "index"
shallowPath = "shallow"
modulePath = "modules"
objectsPath = "objects"
packPath = "pack"
refsPath = "refs"
tmpPackedRefsPrefix = "._packed-refs"
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")
// ErrPackedRefsDuplicatedRef is returned when a duplicated reference is
// found in the packed-ref file. This is usually the case for corrupted git
// repositories.
ErrPackedRefsDuplicatedRef = errors.New("duplicated ref found in packed-ref file")
// ErrPackedRefsBadFormat is returned when the packed-ref file corrupt.
ErrPackedRefsBadFormat = errors.New("malformed packed-ref")
// ErrSymRefTargetNotFound is returned when a symbolic reference is
// targeting a non-existing object. This usually means the repository
// is corrupt.
ErrSymRefTargetNotFound = errors.New("symbolic reference target 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 billy.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 billy.Filesystem) *DotGit {
return &DotGit{fs: fs}
}
// Initialize creates all the folder scaffolding.
func (d *DotGit) Initialize() error {
mustExists := []string{
d.fs.Join("objects", "info"),
d.fs.Join("objects", "pack"),
d.fs.Join("refs", "heads"),
d.fs.Join("refs", "tags"),
}
for _, path := range mustExists {
_, err := d.fs.Stat(path)
if err == nil {
continue
}
if !os.IsNotExist(err) {
return err
}
if err := d.fs.MkdirAll(path, os.ModeDir|os.ModePerm); err != nil {
return err
}
}
return nil
}
// ConfigWriter returns a file pointer for write to the config file
func (d *DotGit) ConfigWriter() (billy.File, error) {
return d.fs.Create(configPath)
}
// Config returns a file pointer for read to the config file
func (d *DotGit) Config() (billy.File, error) {
return d.fs.Open(configPath)
}
// IndexWriter returns a file pointer for write to the index file
func (d *DotGit) IndexWriter() (billy.File, error) {
return d.fs.Create(indexPath)
}
// Index returns a file pointer for read to the index file
func (d *DotGit) Index() (billy.File, error) {
return d.fs.Open(indexPath)
}
// ShallowWriter returns a file pointer for write to the shallow file
func (d *DotGit) ShallowWriter() (billy.File, error) {
return d.fs.Create(shallowPath)
}
// Shallow returns a file pointer for read to the shallow file
func (d *DotGit) Shallow() (billy.File, error) {
f, err := d.fs.Open(shallowPath)
if err != nil {
if os.IsNotExist(err) {
return nil, nil
}
return nil, err
}
return f, 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() ([]plumbing.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 []plumbing.Hash
for _, f := range files {
if !strings.HasSuffix(f.Name(), packExt) {
continue
}
n := f.Name()
h := plumbing.NewHash(n[5 : len(n)-5]) //pack-(hash).pack
packs = append(packs, h)
}
return packs, nil
}
func (d *DotGit) objectPackPath(hash plumbing.Hash, extension string) string {
return d.fs.Join(objectsPath, packPath, fmt.Sprintf("pack-%s.%s", hash.String(), extension))
}
func (d *DotGit) objectPackOpen(hash plumbing.Hash, extension string) (billy.File, error) {
pack, err := d.fs.Open(d.objectPackPath(hash, extension))
if err != nil {
if os.IsNotExist(err) {
return nil, ErrPackfileNotFound
}
return nil, err
}
return pack, nil
}
// ObjectPack returns a fs.File of the given packfile
func (d *DotGit) ObjectPack(hash plumbing.Hash) (billy.File, error) {
return d.objectPackOpen(hash, `pack`)
}
// ObjectPackIdx returns a fs.File of the index file for a given packfile
func (d *DotGit) ObjectPackIdx(hash plumbing.Hash) (billy.File, error) {
return d.objectPackOpen(hash, `idx`)
}
func (d *DotGit) DeleteOldObjectPackAndIndex(hash plumbing.Hash, t time.Time) error {
path := d.objectPackPath(hash, `pack`)
if !t.IsZero() {
fi, err := d.fs.Stat(path)
if err != nil {
return err
}
// too new, skip deletion.
if !fi.ModTime().Before(t) {
return nil
}
}
err := d.fs.Remove(path)
if err != nil {
return err
}
return d.fs.Remove(d.objectPackPath(hash, `idx`))
}
// NewObject return a writer for a new object file.
func (d *DotGit) NewObject() (*ObjectWriter, error) {
return newObjectWriter(d.fs)
}
// Objects returns a slice with the hashes of objects found under the
// .git/objects/ directory.
func (d *DotGit) Objects() ([]plumbing.Hash, error) {
var objects []plumbing.Hash
err := d.ForEachObjectHash(func(hash plumbing.Hash) error {
objects = append(objects, hash)
return nil
})
if err != nil {
return nil, err
}
return objects, nil
}
// Objects returns a slice with the hashes of objects found under the
// .git/objects/ directory.
func (d *DotGit) ForEachObjectHash(fun func(plumbing.Hash) error) error {
files, err := d.fs.ReadDir(objectsPath)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
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 err
}
for _, o := range d {
err = fun(plumbing.NewHash(base + o.Name()))
if err != nil {
return err
}
}
}
}
return nil
}
func (d *DotGit) objectPath(h plumbing.Hash) string {
hash := h.String()
return d.fs.Join(objectsPath, hash[0:2], hash[2:40])
}
// Object returns a fs.File pointing the object file, if exists
func (d *DotGit) Object(h plumbing.Hash) (billy.File, error) {
return d.fs.Open(d.objectPath(h))
}
// ObjectStat returns a os.FileInfo pointing the object file, if exists
func (d *DotGit) ObjectStat(h plumbing.Hash) (os.FileInfo, error) {
return d.fs.Stat(d.objectPath(h))
}
// ObjectDelete removes the object file, if exists
func (d *DotGit) ObjectDelete(h plumbing.Hash) error {
return d.fs.Remove(d.objectPath(h))
}
func (d *DotGit) readReferenceFrom(rd io.Reader, name string) (ref *plumbing.Reference, err error) {
b, err := stdioutil.ReadAll(rd)
if err != nil {
return nil, err
}
line := strings.TrimSpace(string(b))
return plumbing.NewReferenceFromStrings(name, line), nil
}
func (d *DotGit) checkReferenceAndTruncate(f billy.File, old *plumbing.Reference) error {
if old == nil {
return nil
}
ref, err := d.readReferenceFrom(f, old.Name().String())
if err != nil {
return err
}
if ref.Hash() != old.Hash() {
return fmt.Errorf("reference has changed concurrently")
}
_, err = f.Seek(0, io.SeekStart)
if err != nil {
return err
}
return f.Truncate(0)
}
func (d *DotGit) SetRef(r, old *plumbing.Reference) error {
var content string
switch r.Type() {
case plumbing.SymbolicReference:
content = fmt.Sprintf("ref: %s\n", r.Target())
case plumbing.HashReference:
content = fmt.Sprintln(r.Hash().String())
}
fileName := r.Name().String()
return d.setRef(fileName, content, old)
}
// Refs scans the git directory collecting references, which it returns.
// Symbolic references are resolved and included in the output.
func (d *DotGit) Refs() ([]*plumbing.Reference, error) {
var refs []*plumbing.Reference
var seen = make(map[plumbing.ReferenceName]bool)
if err := d.addRefsFromRefDir(&refs, seen); err != nil {
return nil, err
}
if err := d.addRefsFromPackedRefs(&refs, seen); err != nil {
return nil, err
}
if err := d.addRefFromHEAD(&refs); err != nil {
return nil, err
}
return refs, nil
}
// Ref returns the reference for a given reference name.
func (d *DotGit) Ref(name plumbing.ReferenceName) (*plumbing.Reference, error) {
ref, err := d.readReferenceFile(".", name.String())
if err == nil {
return ref, nil
}
return d.packedRef(name)
}
func (d *DotGit) findPackedRefsInFile(f billy.File) ([]*plumbing.Reference, error) {
s := bufio.NewScanner(f)
var refs []*plumbing.Reference
for s.Scan() {
ref, err := d.processLine(s.Text())
if err != nil {
return nil, err
}
if ref != nil {
refs = append(refs, ref)
}
}
return refs, s.Err()
}
func (d *DotGit) findPackedRefs() ([]*plumbing.Reference, error) {
f, err := d.fs.Open(packedRefsPath)
if err != nil {
if os.IsNotExist(err) {
return nil, nil
}
return nil, err
}
defer ioutil.CheckClose(f, &err)
return d.findPackedRefsInFile(f)
}
func (d *DotGit) packedRef(name plumbing.ReferenceName) (*plumbing.Reference, error) {
refs, err := d.findPackedRefs()
if err != nil {
return nil, err
}
for _, ref := range refs {
if ref.Name() == name {
return ref, nil
}
}
return nil, plumbing.ErrReferenceNotFound
}
// RemoveRef removes a reference by name.
func (d *DotGit) RemoveRef(name plumbing.ReferenceName) error {
path := d.fs.Join(".", name.String())
_, err := d.fs.Stat(path)
if err == nil {
err = d.fs.Remove(path)
// Drop down to remove it from the packed refs file, too.
}
if err != nil && !os.IsNotExist(err) {
return err
}
return d.rewritePackedRefsWithoutRef(name)
}
func (d *DotGit) addRefsFromPackedRefs(refs *[]*plumbing.Reference, seen map[plumbing.ReferenceName]bool) (err error) {
packedRefs, err := d.findPackedRefs()
if err != nil {
return err
}
for _, ref := range packedRefs {
if !seen[ref.Name()] {
*refs = append(*refs, ref)
seen[ref.Name()] = true
}
}
return nil
}
func (d *DotGit) addRefsFromPackedRefsFile(refs *[]*plumbing.Reference, f billy.File, seen map[plumbing.ReferenceName]bool) (err error) {
packedRefs, err := d.findPackedRefsInFile(f)
if err != nil {
return err
}
for _, ref := range packedRefs {
if !seen[ref.Name()] {
*refs = append(*refs, ref)
seen[ref.Name()] = true
}
}
return nil
}
func (d *DotGit) openAndLockPackedRefs(doCreate bool) (
pr billy.File, err error) {
var f billy.File
defer func() {
if err != nil && f != nil {
ioutil.CheckClose(f, &err)
}
}()
// File mode is retrieved from a constant defined in the target specific
// files (dotgit_rewrite_packed_refs_*). Some modes are not available
// in all filesystems.
openFlags := openAndLockPackedRefsMode
if doCreate {
openFlags |= os.O_CREATE
}
// Keep trying to open and lock the file until we're sure the file
// didn't change between the open and the lock.
for {
f, err = d.fs.OpenFile(packedRefsPath, openFlags, 0600)
if err != nil {
if os.IsNotExist(err) && !doCreate {
return nil, nil
}
return nil, err
}
fi, err := d.fs.Stat(packedRefsPath)
if err != nil {
return nil, err
}
mtime := fi.ModTime()
err = f.Lock()
if err != nil {
return nil, err
}
fi, err = d.fs.Stat(packedRefsPath)
if err != nil {
return nil, err
}
if mtime.Equal(fi.ModTime()) {
break
}
// The file has changed since we opened it. Close and retry.
err = f.Close()
if err != nil {
return nil, err
}
}
return f, nil
}
func (d *DotGit) rewritePackedRefsWithoutRef(name plumbing.ReferenceName) (err error) {
pr, err := d.openAndLockPackedRefs(false)
if err != nil {
return err
}
if pr == nil {
return nil
}
defer ioutil.CheckClose(pr, &err)
// Creating the temp file in the same directory as the target file
// improves our chances for rename operation to be atomic.
tmp, err := d.fs.TempFile("", tmpPackedRefsPrefix)
if err != nil {
return err
}
tmpName := tmp.Name()
defer func() {
ioutil.CheckClose(tmp, &err)
_ = d.fs.Remove(tmpName) // don't check err, we might have renamed it
}()
s := bufio.NewScanner(pr)
found := false
for s.Scan() {
line := s.Text()
ref, err := d.processLine(line)
if err != nil {
return err
}
if ref != nil && ref.Name() == name {
found = true
continue
}
if _, err := fmt.Fprintln(tmp, line); err != nil {
return err
}
}
if err := s.Err(); err != nil {
return err
}
if !found {
return nil
}
return d.rewritePackedRefsWhileLocked(tmp, pr)
}
// process lines from a packed-refs file
func (d *DotGit) processLine(line string) (*plumbing.Reference, error) {
if len(line) == 0 {
return nil, nil
}
switch line[0] {
case '#': // comment - ignore
return nil, nil
case '^': // annotated tag commit of the previous line - ignore
return nil, nil
default:
ws := strings.Split(line, " ") // hash then ref
if len(ws) != 2 {
return nil, ErrPackedRefsBadFormat
}
return plumbing.NewReferenceFromStrings(ws[1], ws[0]), nil
}
}
func (d *DotGit) addRefsFromRefDir(refs *[]*plumbing.Reference, seen map[plumbing.ReferenceName]bool) error {
return d.walkReferencesTree(refs, []string{refsPath}, seen)
}
func (d *DotGit) walkReferencesTree(refs *[]*plumbing.Reference, relPath []string, seen map[plumbing.ReferenceName]bool) error {
files, err := d.fs.ReadDir(d.fs.Join(relPath...))
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
for _, f := range files {
newRelPath := append(append([]string(nil), relPath...), f.Name())
if f.IsDir() {
if err = d.walkReferencesTree(refs, newRelPath, seen); err != nil {
return err
}
continue
}
ref, err := d.readReferenceFile(".", strings.Join(newRelPath, "/"))
if err != nil {
return err
}
if ref != nil && !seen[ref.Name()] {
*refs = append(*refs, ref)
seen[ref.Name()] = true
}
}
return nil
}
func (d *DotGit) addRefFromHEAD(refs *[]*plumbing.Reference) error {
ref, err := d.readReferenceFile(".", "HEAD")
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
*refs = append(*refs, ref)
return nil
}
func (d *DotGit) readReferenceFile(path, name string) (ref *plumbing.Reference, err error) {
path = d.fs.Join(path, d.fs.Join(strings.Split(name, "/")...))
f, err := d.fs.Open(path)
if err != nil {
return nil, err
}
defer ioutil.CheckClose(f, &err)
return d.readReferenceFrom(f, name)
}
func (d *DotGit) CountLooseRefs() (int, error) {
var refs []*plumbing.Reference
var seen = make(map[plumbing.ReferenceName]bool)
if err := d.addRefsFromRefDir(&refs, seen); err != nil {
return 0, err
}
return len(refs), nil
}
// PackRefs packs all loose refs into the packed-refs file.
//
// This implementation only works under the assumption that the view
// of the file system won't be updated during this operation. This
// strategy would not work on a general file system though, without
// locking each loose reference and checking it again before deleting
// the file, because otherwise an updated reference could sneak in and
// then be deleted by the packed-refs process. Alternatively, every
// ref update could also lock packed-refs, so only one lock is
// required during ref-packing. But that would worsen performance in
// the common case.
//
// TODO: add an "all" boolean like the `git pack-refs --all` flag.
// When `all` is false, it would only pack refs that have already been
// packed, plus all tags.
func (d *DotGit) PackRefs() (err error) {
// Lock packed-refs, and create it if it doesn't exist yet.
f, err := d.openAndLockPackedRefs(true)
if err != nil {
return err
}
defer ioutil.CheckClose(f, &err)
// Gather all refs using addRefsFromRefDir and addRefsFromPackedRefs.
var refs []*plumbing.Reference
seen := make(map[plumbing.ReferenceName]bool)
if err := d.addRefsFromRefDir(&refs, seen); err != nil {
return err
}
if len(refs) == 0 {
// Nothing to do!
return nil
}
numLooseRefs := len(refs)
if err := d.addRefsFromPackedRefsFile(&refs, f, seen); err != nil {
return err
}
// Write them all to a new temp packed-refs file.
tmp, err := d.fs.TempFile("", tmpPackedRefsPrefix)
if err != nil {
return err
}
tmpName := tmp.Name()
defer func() {
ioutil.CheckClose(tmp, &err)
_ = d.fs.Remove(tmpName) // don't check err, we might have renamed it
}()
w := bufio.NewWriter(tmp)
for _, ref := range refs {
_, err := w.WriteString(ref.String() + "\n")
if err != nil {
return err
}
}
err = w.Flush()
if err != nil {
return err
}
// Rename the temp packed-refs file.
err = d.rewritePackedRefsWhileLocked(tmp, f)
if err != nil {
return err
}
// Delete all the loose refs, while still holding the packed-refs
// lock.
for _, ref := range refs[:numLooseRefs] {
path := d.fs.Join(".", ref.Name().String())
err = d.fs.Remove(path)
if err != nil && !os.IsNotExist(err) {
return err
}
}
return nil
}
// Module return a billy.Filesystem pointing to the module folder
func (d *DotGit) Module(name string) (billy.Filesystem, error) {
return d.fs.Chroot(d.fs.Join(modulePath, name))
}
// Alternates returns DotGit(s) based off paths in objects/info/alternates if
// available. This can be used to checks if it's a shared repository.
func (d *DotGit) Alternates() ([]*DotGit, error) {
altpath := d.fs.Join("objects", "info", "alternates")
f, err := d.fs.Open(altpath)
if err != nil {
return nil, err
}
defer f.Close()
var alternates []*DotGit
// Read alternate paths line-by-line and create DotGit objects.
scanner := bufio.NewScanner(f)
for scanner.Scan() {
path := scanner.Text()
if !filepath.IsAbs(path) {
// For relative paths, we can perform an internal conversion to
// slash so that they work cross-platform.
slashPath := filepath.ToSlash(path)
// If the path is not absolute, it must be relative to object
// database (.git/objects/info).
// https://www.kernel.org/pub/software/scm/git/docs/gitrepository-layout.html
// Hence, derive a path relative to DotGit's root.
// "../../../reponame/.git/" -> "../../reponame/.git"
// Remove the first ../
relpath := filepath.Join(strings.Split(slashPath, "/")[1:]...)
normalPath := filepath.FromSlash(relpath)
path = filepath.Join(d.fs.Root(), normalPath)
}
fs := osfs.New(filepath.Dir(path))
alternates = append(alternates, New(fs))
}
if err = scanner.Err(); err != nil {
return nil, err
}
return alternates, nil
}
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'
}
