forked from git-lfs/git-lfs
/
filetools.go
395 lines (341 loc) · 10.9 KB
/
filetools.go
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// Package tools contains other helper functions too small to justify their own package
// NOTE: Subject to change, do not rely on this package from outside git-lfs source
package tools
import (
"bufio"
"encoding/hex"
"fmt"
"io"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"sync/atomic"
"github.com/git-lfs/git-lfs/filepathfilter"
)
// FileOrDirExists determines if a file/dir exists, returns IsDir() results too.
func FileOrDirExists(path string) (exists bool, isDir bool) {
fi, err := os.Stat(path)
if err != nil {
return false, false
} else {
return true, fi.IsDir()
}
}
// FileExists determines if a file (NOT dir) exists.
func FileExists(path string) bool {
ret, isDir := FileOrDirExists(path)
return ret && !isDir
}
// DirExists determines if a dir (NOT file) exists.
func DirExists(path string) bool {
ret, isDir := FileOrDirExists(path)
return ret && isDir
}
// FileExistsOfSize determines if a file exists and is of a specific size.
func FileExistsOfSize(path string, sz int64) bool {
fi, err := os.Stat(path)
if err != nil {
return false
}
return !fi.IsDir() && fi.Size() == sz
}
// ResolveSymlinks ensures that if the path supplied is a symlink, it is
// resolved to the actual concrete path
func ResolveSymlinks(path string) string {
if len(path) == 0 {
return path
}
if resolved, err := filepath.EvalSymlinks(path); err == nil {
return resolved
}
return path
}
// RenameFileCopyPermissions moves srcfile to destfile, replacing destfile if
// necessary and also copying the permissions of destfile if it already exists
func RenameFileCopyPermissions(srcfile, destfile string) error {
info, err := os.Stat(destfile)
if os.IsNotExist(err) {
// no original file
} else if err != nil {
return err
} else {
if err := os.Chmod(srcfile, info.Mode()); err != nil {
return fmt.Errorf("can't set filemode on file %q: %v", srcfile, err)
}
}
if err := os.Rename(srcfile, destfile); err != nil {
return fmt.Errorf("cannot replace %q with %q: %v", destfile, srcfile, err)
}
return nil
}
// CleanPaths splits the given `paths` argument by the delimiter argument, and
// then "cleans" that path according to the path.Clean function (see
// https://golang.org/pkg/path#Clean).
// Note always cleans to '/' path separators regardless of platform (git friendly)
func CleanPaths(paths, delim string) (cleaned []string) {
// If paths is an empty string, splitting it will yield [""], which will
// become the path ".". To avoid this, bail out if trimmed paths
// argument is empty.
if paths = strings.TrimSpace(paths); len(paths) == 0 {
return
}
for _, part := range strings.Split(paths, delim) {
part = strings.TrimSpace(part)
// Remove trailing `/` or `\`, but only the first one.
for _, sep := range []string{`/`, `\`} {
if strings.HasSuffix(part, sep) {
part = strings.TrimSuffix(part, sep)
break
}
}
cleaned = append(cleaned, part)
}
return cleaned
}
// VerifyFileHash reads a file and verifies whether the SHA is correct
// Returns an error if there is a problem
func VerifyFileHash(oid, path string) error {
f, err := os.Open(path)
if err != nil {
return err
}
defer f.Close()
h := NewLfsContentHash()
_, err = io.Copy(h, f)
if err != nil {
return err
}
calcOid := hex.EncodeToString(h.Sum(nil))
if calcOid != oid {
return fmt.Errorf("File %q has an invalid hash %s, expected %s", path, calcOid, oid)
}
return nil
}
// FastWalkCallback is the signature for the callback given to FastWalkGitRepo()
type FastWalkCallback func(parentDir string, info os.FileInfo, err error)
// FastWalkGitRepo is a more optimal implementation of filepath.Walk for a Git
// repo. The callback guaranteed to be called sequentially. The function returns
// once all files and errors have triggered callbacks.
// It differs in the following ways:
// * Uses goroutines to parallelise large dirs and descent into subdirs
// * Does not provide sorted output; parents will always be before children but
// there are no other guarantees. Use parentDir argument in the callback to
// determine absolute path rather than tracking it yourself
// * Automatically ignores any .git directories
// * Respects .gitignore contents and skips ignored files/dirs
//
// rootDir - Absolute path to the top of the repository working directory
func FastWalkGitRepo(rootDir string, cb FastWalkCallback) {
walker := fastWalkWithExcludeFiles(rootDir, ".gitignore")
for file := range walker.ch {
cb(file.ParentDir, file.Info, file.Err)
}
}
// Returned from FastWalk with parent directory context
// This is needed because FastWalk can provide paths out of order so the
// parent dir cannot be implied
type fastWalkInfo struct {
ParentDir string
Info os.FileInfo
Err error
}
type fastWalker struct {
rootDir string
excludeFilename string
ch chan fastWalkInfo
limit int32
cur *int32
wg *sync.WaitGroup
}
// fastWalkWithExcludeFiles walks the contents of a dir, respecting
// include/exclude patterns and also loading new exlude patterns from files
// named excludeFilename in directories walked
//
// rootDir - Absolute path to the top of the repository working directory
func fastWalkWithExcludeFiles(rootDir, excludeFilename string) *fastWalker {
excludePaths := []filepathfilter.Pattern{
filepathfilter.NewPattern(".git"),
filepathfilter.NewPattern("**/.git"),
}
limit, _ := strconv.Atoi(os.Getenv("LFS_FASTWALK_LIMIT"))
if limit < 1 {
limit = runtime.GOMAXPROCS(-1) * 20
}
c := int32(0)
w := &fastWalker{
rootDir: rootDir,
excludeFilename: excludeFilename,
limit: int32(limit),
cur: &c,
ch: make(chan fastWalkInfo, 256),
wg: &sync.WaitGroup{},
}
go func() {
dirFi, err := os.Stat(w.rootDir)
if err != nil {
w.ch <- fastWalkInfo{Err: err}
return
}
w.Walk(true, "", dirFi, excludePaths)
w.Wait()
}()
return w
}
// Walk is the main recursive implementation of fast walk.
// Sends the file/dir and any contents to the channel so long as it passes the
// include/exclude filter. If a dir, parses any excludeFilename found and updates
// the excludePaths with its content before (parallel) recursing into contents
// Also splits large directories into multiple goroutines.
// Increments waitg.Add(1) for each new goroutine launched internally
//
// workDir - Relative path inside the repository
func (w *fastWalker) Walk(isRoot bool, workDir string, itemFi os.FileInfo,
excludePaths []filepathfilter.Pattern) {
var fullPath string // Absolute path to the current file or dir
var parentWorkDir string // Absolute path to the workDir inside the repository
if isRoot {
fullPath = w.rootDir
} else {
parentWorkDir = join(w.rootDir, workDir)
fullPath = join(parentWorkDir, itemFi.Name())
}
workPath := join(workDir, itemFi.Name())
if !filepathfilter.NewFromPatterns(nil, excludePaths).Allows(workPath) {
return
}
w.ch <- fastWalkInfo{ParentDir: parentWorkDir, Info: itemFi}
if !itemFi.IsDir() {
// Nothing more to do if this is not a dir
return
}
var childWorkDir string
if !isRoot {
childWorkDir = join(workDir, itemFi.Name())
}
if len(w.excludeFilename) > 0 {
possibleExcludeFile := join(fullPath, w.excludeFilename)
var err error
excludePaths, err = loadExcludeFilename(possibleExcludeFile, childWorkDir, excludePaths)
if err != nil {
w.ch <- fastWalkInfo{Err: err}
}
}
// The absolute optimal way to scan would be File.Readdirnames but we
// still need the Stat() to know whether something is a dir, so use
// File.Readdir instead. Means we can provide os.FileInfo to callers like
// filepath.Walk as a bonus.
df, err := os.Open(fullPath)
if err != nil {
w.ch <- fastWalkInfo{Err: err}
return
}
// The number of items in a dir we process in each goroutine
jobSize := 100
for children, err := df.Readdir(jobSize); err == nil; children, err = df.Readdir(jobSize) {
// Parallelise all dirs, and chop large dirs into batches
w.walk(children, func(subitems []os.FileInfo) {
for _, childFi := range subitems {
w.Walk(false, childWorkDir, childFi, excludePaths)
}
})
}
df.Close()
if err != nil && err != io.EOF {
w.ch <- fastWalkInfo{Err: err}
}
}
func (w *fastWalker) walk(children []os.FileInfo, fn func([]os.FileInfo)) {
cur := atomic.AddInt32(w.cur, 1)
if cur > w.limit {
fn(children)
atomic.AddInt32(w.cur, -1)
return
}
w.wg.Add(1)
go func() {
fn(children)
w.wg.Done()
atomic.AddInt32(w.cur, -1)
}()
}
func (w *fastWalker) Wait() {
w.wg.Wait()
close(w.ch)
}
// loadExcludeFilename reads the given file in gitignore format and returns a
// revised array of exclude paths if there are any changes.
// If any changes are made a copy of the array is taken so the original is not
// modified
func loadExcludeFilename(filename, workDir string, excludePaths []filepathfilter.Pattern) ([]filepathfilter.Pattern, error) {
f, err := os.OpenFile(filename, os.O_RDONLY, 0644)
if err != nil {
if os.IsNotExist(err) {
return excludePaths, nil
}
return excludePaths, err
}
defer f.Close()
retPaths := excludePaths
modified := false
scanner := bufio.NewScanner(f)
for scanner.Scan() {
line := strings.TrimSpace(scanner.Text())
// Skip blanks, comments and negations (not supported right now)
if len(line) == 0 || strings.HasPrefix(line, "#") || strings.HasPrefix(line, "!") {
continue
}
if !modified {
// copy on write
retPaths = make([]filepathfilter.Pattern, len(excludePaths))
copy(retPaths, excludePaths)
modified = true
}
path := line
// Add pattern in context if exclude has separator, or no wildcard
// Allow for both styles of separator at this point
if strings.ContainsAny(path, "/\\") ||
!strings.Contains(path, "*") {
path = join(workDir, line)
}
retPaths = append(retPaths, filepathfilter.NewPattern(path))
}
return retPaths, nil
}
func join(paths ...string) string {
ne := make([]string, 0, len(paths))
for _, p := range paths {
if len(p) > 0 {
ne = append(ne, p)
}
}
return strings.Join(ne, "/")
}
// SetFileWriteFlag changes write permissions on a file
// Used to make a file read-only or not. When writeEnabled = false, the write
// bit is removed for all roles. When writeEnabled = true, the behaviour is
// different per platform:
// On Mac & Linux, the write bit is set only on the owner as per default umask.
// All other bits are unaffected.
// On Windows, all the write bits are set since Windows doesn't support Unix permissions.
func SetFileWriteFlag(path string, writeEnabled bool) error {
stat, err := os.Stat(path)
if err != nil {
return err
}
mode := uint32(stat.Mode())
if (writeEnabled && (mode&0200) > 0) ||
(!writeEnabled && (mode&0222) == 0) {
// no change needed
return nil
}
if writeEnabled {
mode = mode | 0200 // set owner write only
// Go's own Chmod makes Windows set all though
} else {
mode = mode &^ 0222 // disable all write
}
return os.Chmod(path, os.FileMode(mode))
}