package fsutil import ( "context" "hash" "io" "os" "path/filepath" "strconv" "sync" "time" "github.com/opencontainers/go-digest" "github.com/pkg/errors" "golang.org/x/sync/errgroup" ) type WriteToFunc func(context.Context, string, io.WriteCloser) error type DiskWriterOpt struct { AsyncDataCb WriteToFunc SyncDataCb WriteToFunc NotifyCb func(ChangeKind, string, os.FileInfo, error) error ContentHasher ContentHasher Filter FilterFunc } type FilterFunc func(*Stat) bool type DiskWriter struct { opt DiskWriterOpt dest string wg sync.WaitGroup ctx context.Context cancel func() eg *errgroup.Group filter FilterFunc } func NewDiskWriter(ctx context.Context, dest string, opt DiskWriterOpt) (*DiskWriter, error) { if opt.SyncDataCb == nil && opt.AsyncDataCb == nil { return nil, errors.New("no data callback specified") } if opt.SyncDataCb != nil && opt.AsyncDataCb != nil { return nil, errors.New("can't specify both sync and async data callbacks") } ctx, cancel := context.WithCancel(ctx) eg, ctx := errgroup.WithContext(ctx) return &DiskWriter{ opt: opt, dest: dest, eg: eg, ctx: ctx, cancel: cancel, filter: opt.Filter, }, nil } func (dw *DiskWriter) Wait(ctx context.Context) error { return dw.eg.Wait() } func (dw *DiskWriter) HandleChange(kind ChangeKind, p string, fi os.FileInfo, err error) (retErr error) { if err != nil { return err } select { case <-dw.ctx.Done(): return dw.ctx.Err() default: } defer func() { if retErr != nil { dw.cancel() } }() destPath := filepath.Join(dw.dest, filepath.FromSlash(p)) if kind == ChangeKindDelete { // todo: no need to validate if diff is trusted but is it always? if err := os.RemoveAll(destPath); err != nil { return errors.Wrapf(err, "failed to remove: %s", destPath) } if dw.opt.NotifyCb != nil { if err := dw.opt.NotifyCb(kind, p, nil, nil); err != nil { return err } } return nil } stat, ok := fi.Sys().(*Stat) if !ok { return errors.Errorf("%s invalid change without stat information", p) } statCopy := *stat if dw.filter != nil { if ok := dw.filter(&statCopy); !ok { return nil } } rename := true oldFi, err := os.Lstat(destPath) if err != nil { if os.IsNotExist(err) { if kind != ChangeKindAdd { return errors.Wrapf(err, "invalid addition: %s", destPath) } rename = false } else { return errors.Wrapf(err, "failed to stat %s", destPath) } } if oldFi != nil && fi.IsDir() && oldFi.IsDir() { if err := rewriteMetadata(destPath, &statCopy); err != nil { return errors.Wrapf(err, "error setting dir metadata for %s", destPath) } return nil } newPath := destPath if rename { newPath = filepath.Join(filepath.Dir(destPath), ".tmp."+nextSuffix()) } isRegularFile := false switch { case fi.IsDir(): if err := os.Mkdir(newPath, fi.Mode()); err != nil { return errors.Wrapf(err, "failed to create dir %s", newPath) } case fi.Mode()&os.ModeDevice != 0 || fi.Mode()&os.ModeNamedPipe != 0: if err := handleTarTypeBlockCharFifo(newPath, &statCopy); err != nil { return errors.Wrapf(err, "failed to create device %s", newPath) } case fi.Mode()&os.ModeSymlink != 0: if err := os.Symlink(statCopy.Linkname, newPath); err != nil { return errors.Wrapf(err, "failed to symlink %s", newPath) } case statCopy.Linkname != "": if err := os.Link(filepath.Join(dw.dest, statCopy.Linkname), newPath); err != nil { return errors.Wrapf(err, "failed to link %s to %s", newPath, statCopy.Linkname) } default: isRegularFile = true file, err := os.OpenFile(newPath, os.O_CREATE|os.O_WRONLY, fi.Mode()) //todo: windows if err != nil { return errors.Wrapf(err, "failed to create %s", newPath) } if dw.opt.SyncDataCb != nil { if err := dw.processChange(ChangeKindAdd, p, fi, file); err != nil { file.Close() return err } break } if err := file.Close(); err != nil { return errors.Wrapf(err, "failed to close %s", newPath) } } if err := rewriteMetadata(newPath, &statCopy); err != nil { return errors.Wrapf(err, "error setting metadata for %s", newPath) } if rename { if oldFi.IsDir() != fi.IsDir() { if err := os.RemoveAll(destPath); err != nil { return errors.Wrapf(err, "failed to remove %s", destPath) } } if err := os.Rename(newPath, destPath); err != nil { return errors.Wrapf(err, "failed to rename %s to %s", newPath, destPath) } } if isRegularFile { if dw.opt.AsyncDataCb != nil { dw.requestAsyncFileData(p, destPath, fi) } } else { return dw.processChange(kind, p, fi, nil) } return nil } func (dw *DiskWriter) requestAsyncFileData(p, dest string, fi os.FileInfo) { // todo: limit worker threads dw.eg.Go(func() error { if err := dw.processChange(ChangeKindAdd, p, fi, &lazyFileWriter{ dest: dest, }); err != nil { return err } return chtimes(dest, fi.ModTime().UnixNano()) // TODO: parent dirs }) } func (dw *DiskWriter) processChange(kind ChangeKind, p string, fi os.FileInfo, w io.WriteCloser) error { origw := w var hw *hashedWriter if dw.opt.NotifyCb != nil { var err error if hw, err = newHashWriter(dw.opt.ContentHasher, fi, w); err != nil { return err } w = hw } if origw != nil { fn := dw.opt.SyncDataCb if fn == nil && dw.opt.AsyncDataCb != nil { fn = dw.opt.AsyncDataCb } if err := fn(dw.ctx, p, w); err != nil { return err } } else { if hw != nil { hw.Close() } } if hw != nil { return dw.opt.NotifyCb(kind, p, hw, nil) } return nil } type hashedWriter struct { os.FileInfo io.Writer h hash.Hash w io.WriteCloser dgst digest.Digest } func newHashWriter(ch ContentHasher, fi os.FileInfo, w io.WriteCloser) (*hashedWriter, error) { stat, ok := fi.Sys().(*Stat) if !ok { return nil, errors.Errorf("invalid change without stat information") } h, err := ch(stat) if err != nil { return nil, err } hw := &hashedWriter{ FileInfo: fi, Writer: io.MultiWriter(w, h), h: h, w: w, } return hw, nil } func (hw *hashedWriter) Close() error { hw.dgst = digest.NewDigest(digest.SHA256, hw.h) if hw.w != nil { return hw.w.Close() } return nil } func (hw *hashedWriter) Digest() digest.Digest { return hw.dgst } type lazyFileWriter struct { dest string ctx context.Context f *os.File fileMode *os.FileMode } func (lfw *lazyFileWriter) Write(dt []byte) (int, error) { if lfw.f == nil { file, err := os.OpenFile(lfw.dest, os.O_WRONLY, 0) //todo: windows if os.IsPermission(err) { // retry after chmod fi, er := os.Stat(lfw.dest) if er == nil { mode := fi.Mode() lfw.fileMode = &mode er = os.Chmod(lfw.dest, mode|0222) if er == nil { file, err = os.OpenFile(lfw.dest, os.O_WRONLY, 0) } } } if err != nil { return 0, errors.Wrapf(err, "failed to open %s", lfw.dest) } lfw.f = file } return lfw.f.Write(dt) } func (lfw *lazyFileWriter) Close() error { var err error if lfw.f != nil { err = lfw.f.Close() } if err == nil && lfw.fileMode != nil { err = os.Chmod(lfw.dest, *lfw.fileMode) } return err } func mkdev(major int64, minor int64) uint32 { return uint32(((minor & 0xfff00) << 12) | ((major & 0xfff) << 8) | (minor & 0xff)) } // Random number state. // We generate random temporary file names so that there's a good // chance the file doesn't exist yet - keeps the number of tries in // TempFile to a minimum. var rand uint32 var randmu sync.Mutex func reseed() uint32 { return uint32(time.Now().UnixNano() + int64(os.Getpid())) } func nextSuffix() string { randmu.Lock() r := rand if r == 0 { r = reseed() } r = r*1664525 + 1013904223 // constants from Numerical Recipes rand = r randmu.Unlock() return strconv.Itoa(int(1e9 + r%1e9))[1:] }