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package fs
import (
"bufio"
"bytes"
"crypto/sha256"
"encoding/hex"
"errors"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
"github.com/git-lfs/git-lfs/v3/tools"
"github.com/git-lfs/git-lfs/v3/tr"
"github.com/rubyist/tracerx"
)
var (
oidRE = regexp.MustCompile(`\A[[:alnum:]]{64}`)
EmptyObjectSHA256 = hex.EncodeToString(sha256.New().Sum(nil))
)
// Environment is a copy of a subset of the interface
// github.com/git-lfs/git-lfs/config.Environment.
//
// For more information, see config/environment.go.
type Environment interface {
Get(key string) (val string, ok bool)
}
// Object represents a locally stored LFS object.
type Object struct {
Oid string
Size int64
}
type Filesystem struct {
GitStorageDir string // parent of objects/lfs (may be same as GitDir but may not)
LFSStorageDir string // parent of lfs objects and tmp dirs. Default: ".git/lfs"
ReferenceDirs []string // alternative local media dirs (relative to clone reference repo)
lfsobjdir string
tmpdir string
logdir string
repoPerms os.FileMode
mu sync.Mutex
}
func (f *Filesystem) EachObject(fn func(Object) error) error {
var eachErr error
tools.FastWalkDir(f.LFSObjectDir(), func(parentDir string, info os.FileInfo, err error) {
if err != nil {
eachErr = err
return
}
if eachErr != nil || info.IsDir() {
return
}
if oidRE.MatchString(info.Name()) {
fn(Object{Oid: info.Name(), Size: info.Size()})
}
})
return eachErr
}
func (f *Filesystem) ObjectExists(oid string, size int64) bool {
if size == 0 {
return true
}
return tools.FileExistsOfSize(f.ObjectPathname(oid), size)
}
func (f *Filesystem) ObjectPath(oid string) (string, error) {
if len(oid) < 4 {
return "", errors.New(tr.Tr.Get("too short object ID: %q", oid))
}
if oid == EmptyObjectSHA256 {
return os.DevNull, nil
}
dir := f.localObjectDir(oid)
if err := tools.MkdirAll(dir, f); err != nil {
return "", errors.New(tr.Tr.Get("error trying to create local storage directory in %q: %s", dir, err))
}
return filepath.Join(dir, oid), nil
}
func (f *Filesystem) ObjectPathname(oid string) string {
if oid == EmptyObjectSHA256 {
return os.DevNull
}
return filepath.Join(f.localObjectDir(oid), oid)
}
func (f *Filesystem) DecodePathname(path string) string {
return string(DecodePathBytes([]byte(path)))
}
func (f *Filesystem) RepositoryPermissions(executable bool) os.FileMode {
if executable {
return tools.ExecutablePermissions(f.repoPerms)
}
return f.repoPerms
}
/**
* Revert non ascii characters escaped by git or windows (as octal sequences \000) back to bytes.
*/
func DecodePathBytes(path []byte) []byte {
var expression = regexp.MustCompile(`\\[0-9]{3}`)
var buffer bytes.Buffer
// strip quotes if any
if len(path) > 2 && path[0] == '"' && path[len(path)-1] == '"' {
path = path[1 : len(path)-1]
}
base := 0
for _, submatches := range expression.FindAllSubmatchIndex(path, -1) {
buffer.Write(path[base:submatches[0]])
match := string(path[submatches[0]+1 : submatches[0]+4])
k, err := strconv.ParseUint(match, 8, 64)
if err != nil {
return path
} // abort on error
buffer.Write([]byte{byte(k)})
base = submatches[1]
}
buffer.Write(path[base:len(path)])
return buffer.Bytes()
}
func (f *Filesystem) localObjectDir(oid string) string {
return filepath.Join(f.LFSObjectDir(), oid[0:2], oid[2:4])
}
func (f *Filesystem) ObjectReferencePaths(oid string) []string {
if len(f.ReferenceDirs) == 0 {
return nil
}
var paths []string
for _, ref := range f.ReferenceDirs {
paths = append(paths, filepath.Join(ref, oid[0:2], oid[2:4], oid))
}
return paths
}
func (f *Filesystem) LFSObjectDir() string {
f.mu.Lock()
defer f.mu.Unlock()
if len(f.lfsobjdir) == 0 {
f.lfsobjdir = filepath.Join(f.LFSStorageDir, "objects")
tools.MkdirAll(f.lfsobjdir, f)
}
return f.lfsobjdir
}
func (f *Filesystem) LogDir() string {
f.mu.Lock()
defer f.mu.Unlock()
if len(f.logdir) == 0 {
f.logdir = filepath.Join(f.LFSStorageDir, "logs")
tools.MkdirAll(f.logdir, f)
}
return f.logdir
}
func (f *Filesystem) TempDir() string {
f.mu.Lock()
defer f.mu.Unlock()
if len(f.tmpdir) == 0 {
f.tmpdir = filepath.Join(f.LFSStorageDir, "tmp")
tools.MkdirAll(f.tmpdir, f)
}
return f.tmpdir
}
func (f *Filesystem) Cleanup() error {
if f == nil {
return nil
}
return f.cleanupTmp()
}
// New initializes a new *Filesystem with the given directories. gitdir is the
// path to the bare repo, workdir is the path to the repository working
// directory, and lfsdir is the optional path to the `.git/lfs` directory.
// repoPerms is the permissions for directories in the repository.
func New(env Environment, gitdir, workdir, lfsdir string, repoPerms os.FileMode) *Filesystem {
fs := &Filesystem{
GitStorageDir: resolveGitStorageDir(gitdir),
}
fs.ReferenceDirs = resolveReferenceDirs(env, fs.GitStorageDir)
if len(lfsdir) == 0 {
lfsdir = "lfs"
}
if filepath.IsAbs(lfsdir) {
fs.LFSStorageDir = lfsdir
} else {
fs.LFSStorageDir = filepath.Join(fs.GitStorageDir, lfsdir)
}
fs.repoPerms = repoPerms
return fs
}
func resolveReferenceDirs(env Environment, gitStorageDir string) []string {
var references []string
envAlternates, ok := env.Get("GIT_ALTERNATE_OBJECT_DIRECTORIES")
if ok {
splits := strings.Split(envAlternates, string(os.PathListSeparator))
for _, split := range splits {
if dir, ok := existsAlternate(split); ok {
references = append(references, dir)
}
}
}
cloneReferencePath := filepath.Join(gitStorageDir, "objects", "info", "alternates")
if tools.FileExists(cloneReferencePath) {
f, err := os.Open(cloneReferencePath)
if err != nil {
tracerx.Printf("could not open %s: %s",
cloneReferencePath, err)
return nil
}
defer f.Close()
scanner := bufio.NewScanner(f)
for scanner.Scan() {
text := strings.TrimSpace(scanner.Text())
if len(text) == 0 || strings.HasPrefix(text, "#") {
continue
}
if dir, ok := existsAlternate(text); ok {
references = append(references, dir)
}
}
if err := scanner.Err(); err != nil {
tracerx.Printf("could not scan %s: %s",
cloneReferencePath, err)
}
}
return references
}
// existsAlternate takes an object directory given in "objs" (read as a single,
// line from .git/objects/info/alternates). If that is a satisfiable alternates
// directory (i.e., it exists), the directory is returned along with "true". If
// not, the empty string and false is returned instead.
func existsAlternate(objs string) (string, bool) {
objs = strings.TrimSpace(objs)
if strings.HasPrefix(objs, "\"") {
var err error
unquote := strings.LastIndex(objs, "\"")
if unquote == 0 {
return "", false
}
objs, err = strconv.Unquote(objs[:unquote+1])
if err != nil {
return "", false
}
}
storage := filepath.Join(filepath.Dir(objs), "lfs", "objects")
if tools.DirExists(storage) {
return storage, true
}
return "", false
}
// From a git dir, get the location that objects are to be stored (we will store lfs alongside)
// Sometimes there is an additional level of redirect on the .git folder by way of a commondir file
// before you find object storage, e.g. 'git worktree' uses this. It redirects to gitdir either by GIT_DIR
// (during setup) or .git/git-dir: (during use), but this only contains the index etc, the objects
// are found in another git dir via 'commondir'.
func resolveGitStorageDir(gitDir string) string {
commondirpath := filepath.Join(gitDir, "commondir")
if tools.FileExists(commondirpath) && !tools.DirExists(filepath.Join(gitDir, "objects")) {
// no git-dir: prefix in commondir
storage, err := processGitRedirectFile(commondirpath, "")
if err == nil {
return storage
}
}
return gitDir
}
func processGitRedirectFile(file, prefix string) (string, error) {
data, err := os.ReadFile(file)
if err != nil {
return "", err
}
contents := string(data)
var dir string
if len(prefix) > 0 {
if !strings.HasPrefix(contents, prefix) {
// Prefix required & not found
return "", nil
}
dir = strings.TrimSpace(contents[len(prefix):])
} else {
dir = strings.TrimSpace(contents)
}
if !filepath.IsAbs(dir) {
// The .git file contains a relative path.
// Create an absolute path based on the directory the .git file is located in.
dir = filepath.Join(filepath.Dir(file), dir)
}
return dir, nil
}
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