Golang camlistore-org-pkg-schema.NewFileReader类(方法)实例源码

// Empirically:
//  open for read:   req.Flags == 0
//  open for append: req.Flags == 1
//  open for write:  req.Flags == 1
//  open for read/write (+<)   == 2 (bitmask? of?)
//
// open flags are O_WRONLY (1), O_RDONLY (0), or O_RDWR (2). and also
// bitmaks of O_SYMLINK (0x200000) maybe. (from
// fuse_filehandle_xlate_to_oflags in macosx/kext/fuse_file.h)
func (n *mutFile) Open(req *fuse.OpenRequest, res *fuse.OpenResponse, intr fuse.Intr) (fuse.Handle, fuse.Error) {
	mutFileOpen.Incr()

	log.Printf("mutFile.Open: %v: content: %v dir=%v flags=%v mode=%v", n.permanode, n.content, req.Dir, req.Flags, req.Mode)
	r, err := schema.NewFileReader(n.fs.fetcher, n.content)
	if err != nil {
		mutFileOpenError.Incr()
		log.Printf("mutFile.Open: %v", err)
		return nil, fuse.EIO
	}

	// Turn off the OpenDirectIO bit (on by default in rsc fuse server.go),
	// else append operations don't work for some reason.
	res.Flags &= ^fuse.OpenDirectIO

	// Read-only.
	if req.Flags == 0 {
		mutFileOpenRO.Incr()
		log.Printf("mutFile.Open returning read-only file")
		n := &node{
			fs:      n.fs,
			blobref: n.content,
		}
		return &nodeReader{n: n, fr: r}, nil
	}

	mutFileOpenRW.Incr()
	log.Printf("mutFile.Open returning read-write filehandle")

	defer r.Close()
	return n.newHandle(r)
}

// Empirically:
//  open for read:   req.Flags == 0
//  open for append: req.Flags == 1
//  open for write:  req.Flags == 1
//  open for read/write (+<)   == 2 (bitmask? of?)
//
// open flags are O_WRONLY (1), O_RDONLY (0), or O_RDWR (2). and also
// bitmaks of O_SYMLINK (0x200000) maybe. (from
// fuse_filehandle_xlate_to_oflags in macosx/kext/fuse_file.h)
func (n *roFile) Open(ctx context.Context, req *fuse.OpenRequest, res *fuse.OpenResponse) (fs.Handle, error) {
	roFileOpen.Incr()

	if isWriteFlags(req.Flags) {
		return nil, fuse.EPERM
	}

	log.Printf("roFile.Open: %v: content: %v dir=%v flags=%v", n.permanode, n.content, req.Dir, req.Flags)
	r, err := schema.NewFileReader(n.fs.fetcher, n.content)
	if err != nil {
		roFileOpenError.Incr()
		log.Printf("roFile.Open: %v", err)
		return nil, fuse.EIO
	}

	// Turn off the OpenDirectIO bit (on by default in rsc fuse server.go),
	// else append operations don't work for some reason.
	res.Flags &= ^fuse.OpenDirectIO

	// Read-only.
	nod := &node{
		fs:      n.fs,
		blobref: n.content,
	}
	return &nodeReader{n: nod, fr: r}, nil
}

// Empirically:
//  open for read:   req.Flags == 0
//  open for append: req.Flags == 1
//  open for write:  req.Flags == 1
//  open for read/write (+<)   == 2 (bitmask? of?)
//
// open flags are O_WRONLY (1), O_RDONLY (0), or O_RDWR (2). and also
// bitmaks of O_SYMLINK (0x200000) maybe. (from
// fuse_filehandle_xlate_to_oflags in macosx/kext/fuse_file.h)
func (n *mutFile) Open(req *fuse.OpenRequest, res *fuse.OpenResponse, intr fs.Intr) (fs.Handle, fuse.Error) {
	mutFileOpen.Incr()

	log.Printf("mutFile.Open: %v: content: %v dir=%v flags=%v", n.permanode, n.content, req.Dir, req.Flags)
	r, err := schema.NewFileReader(n.fs.fetcher, n.content)
	if err != nil {
		mutFileOpenError.Incr()
		log.Printf("mutFile.Open: %v", err)
		return nil, fuse.EIO
	}

	// Read-only.
	if !isWriteFlags(req.Flags) {
		mutFileOpenRO.Incr()
		log.Printf("mutFile.Open returning read-only file")
		n := &node{
			fs:      n.fs,
			blobref: n.content,
		}
		return &nodeReader{n: n, fr: r}, nil
	}

	mutFileOpenRW.Incr()
	log.Printf("mutFile.Open returning read-write filehandle")

	defer r.Close()
	return n.newHandle(r)
}

func (dh *DownloadHandler) fileInfo(req *http.Request, file blob.Ref) (fi fileInfo, packed bool, err error) {
	// Fast path for blobpacked.
	fi, ok := fileInfoPacked(dh.Search, dh.Fetcher, req, file)
	if debugPack {
		log.Printf("download.go: fileInfoPacked: ok=%v, %+v", ok, fi)
	}
	if ok {
		return fi, true, nil
	}
	fr, err := schema.NewFileReader(dh.blobSource(), file)
	if err != nil {
		return
	}
	mime := dh.ForceMIME
	if mime == "" {
		mime = magic.MIMETypeFromReaderAt(fr)
	}
	if mime == "" {
		mime = "application/octet-stream"
	}
	return fileInfo{
		mime:  mime,
		name:  fr.FileName(),
		size:  fr.Size(),
		rs:    fr,
		close: fr.Close,
	}, false, nil
}

func (ih *ImageHandler) scaleImage(fileRef blob.Ref) (*formatAndImage, error) {
	fr, err := schema.NewFileReader(ih.storageSeekFetcher(), fileRef)
	if err != nil {
		return nil, err
	}
	defer fr.Close()

	var buf bytes.Buffer
	scaleImageGateSlurp.Start()
	n, err := io.Copy(&buf, fr)
	scaleImageGateSlurp.Done()
	imageBytesFetchedVar.Add(n)

	if err != nil {
		return nil, fmt.Errorf("image resize: error reading image %s: %v", fileRef, err)
	}

	scaleImageGateResize.Start()
	defer scaleImageGateResize.Done()

	i, imConfig, err := images.Decode(bytes.NewReader(buf.Bytes()),
		&images.DecodeOpts{MaxWidth: ih.MaxWidth, MaxHeight: ih.MaxHeight})
	if err != nil {
		return nil, err
	}
	b := i.Bounds()
	format := imConfig.Format

	useBytesUnchanged := !imConfig.Modified &&
		format != "cr2" // always recompress CR2 files

	isSquare := b.Dx() == b.Dy()
	if ih.Square && !isSquare {
		useBytesUnchanged = false
		i = squareImage(i)
		b = i.Bounds()
	}

	if !useBytesUnchanged {
		// Encode as a new image
		buf.Reset()
		switch format {
		case "png":
			err = png.Encode(&buf, i)
		case "cr":
			// Recompress CR2 files as JPEG
			format = "jpeg"
			fallthrough
		default:
			err = jpeg.Encode(&buf, i, &jpeg.Options{
				Quality: 90,
			})
		}
		if err != nil {
			return nil, err
		}
	}
	return &formatAndImage{format: format, image: buf.Bytes()}, nil
}

func (dh *DownloadHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request, file blob.Ref) {
	if req.Method != "GET" && req.Method != "HEAD" {
		http.Error(rw, "Invalid download method", 400)
		return
	}
	if req.Header.Get("If-Modified-Since") != "" {
		// Immutable, so any copy's a good copy.
		rw.WriteHeader(http.StatusNotModified)
		return
	}

	fr, err := schema.NewFileReader(dh.blobSource(), file)
	if err != nil {
		http.Error(rw, "Can't serve file: "+err.Error(), 500)
		return
	}
	defer fr.Close()

	schema := fr.FileSchema()
	h := rw.Header()
	h.Set("Content-Length", fmt.Sprintf("%d", schema.SumPartsSize()))
	h.Set("Expires", time.Now().Add(oneYear).Format(http.TimeFormat))

	mimeType := magic.MIMETypeFromReaderAt(fr)
	if dh.ForceMime != "" {
		mimeType = dh.ForceMime
	}
	if mimeType == "" {
		mimeType = "application/octet-stream"
	}
	h.Set("Content-Type", mimeType)
	if mimeType == "application/octet-stream" {
		// Chrome seems to silently do nothing on
		// application/octet-stream unless this is set.
		// Maybe it's confused by lack of URL it recognizes
		// along with lack of mime type?
		rw.Header().Set("Content-Disposition", "attachment; filename=file-"+file.String()+".dat")
	}

	if req.Method == "HEAD" && req.FormValue("verifycontents") != "" {
		vbr, ok := blob.Parse(req.FormValue("verifycontents"))
		if !ok {
			return
		}
		hash := vbr.Hash()
		if hash == nil {
			return
		}
		io.Copy(hash, fr) // ignore errors, caught later
		if vbr.HashMatches(hash) {
			rw.Header().Set("X-Camli-Contents", vbr.String())
		}
		return
	}

	http.ServeContent(rw, req, "", time.Now(), fr)
}

func (ih *ImageHandler) cached(br *blobref.BlobRef) (fr *schema.FileReader, err error) {
	fetchSeeker := blobref.SeekerFromStreamingFetcher(ih.Cache)
	fr, err = schema.NewFileReader(fetchSeeker, br)
	if err != nil {
		return nil, err
	}
	if imageDebug {
		log.Printf("Image Cache: hit: %v\n", br)
	}
	return fr, nil
}

// cached returns a FileReader for the given file schema blobref.
// The FileReader should be closed when done reading.
func (ih *ImageHandler) cached(fileRef blob.Ref) (*schema.FileReader, error) {
	fetchSeeker := blob.SeekerFromStreamingFetcher(ih.Cache)
	fr, err := schema.NewFileReader(fetchSeeker, fileRef)
	if err != nil {
		return nil, err
	}
	if imageDebug {
		log.Printf("Image Cache: hit: %v\n", fileRef)
	}
	return fr, nil
}

func (ih *ImageHandler) scaleImage(buf *bytes.Buffer, file blob.Ref) (format string, err error) {
	fr, err := schema.NewFileReader(ih.storageSeekFetcher(), file)
	if err != nil {
		return format, err
	}
	defer fr.Close()

	_, err = io.Copy(buf, fr)
	if err != nil {
		return format, fmt.Errorf("image resize: error reading image %s: %v", file, err)
	}
	i, imConfig, err := images.Decode(bytes.NewReader(buf.Bytes()),
		&images.DecodeOpts{MaxWidth: ih.MaxWidth, MaxHeight: ih.MaxHeight})
	if err != nil {
		return format, err
	}
	b := i.Bounds()
	format = imConfig.Format

	useBytesUnchanged := !imConfig.Modified &&
		format != "cr2" // always recompress CR2 files

	isSquare := b.Dx() == b.Dy()
	if ih.Square && !isSquare {
		useBytesUnchanged = false
		i = squareImage(i)
		b = i.Bounds()
	}

	if !useBytesUnchanged {
		// Encode as a new image
		buf.Reset()
		switch format {
		case "png":
			err = png.Encode(buf, i)
		case "cr":
			// Recompress CR2 files as JPEG
			format = "jpeg"
			fallthrough
		default:
			err = jpeg.Encode(buf, i, nil)
		}
		if err != nil {
			return format, err
		}
	}
	return format, nil
}

func (s *storage) packFile(fileRef blob.Ref) (err error) {
	s.Logf("Packing file %s ...", fileRef)
	defer func() {
		if err == nil {
			s.Logf("Packed file %s", fileRef)
		} else {
			s.Logf("Error packing file %s: %v", fileRef, err)
		}
	}()

	fr, err := schema.NewFileReader(s, fileRef)
	if err != nil {
		return err
	}
	return newPacker(s, fileRef, fr).pack()
}

// serveRef gets the file at ref from fetcher and serves its contents.
// It is used by Service as a one time handler to serve to the thumbnail child process on localhost.
func serveRef(rw http.ResponseWriter, req *http.Request, ref blob.Ref, fetcher blob.Fetcher) {

	if !httputil.IsGet(req) {
		http.Error(rw, "Invalid download method.", 400)
		return
	}

	if !httputil.IsLocalhost(req) {
		http.Error(rw, "Forbidden.", 403)
		return
	}

	parts := strings.Split(req.URL.Path, "/")
	if len(parts) < 2 {
		http.Error(rw, "Malformed GET URL.", 400)
		return
	}

	blobRef, ok := blob.Parse(parts[1])
	if !ok {
		http.Error(rw, "Malformed GET URL.", 400)
		return
	}

	// only serves its ref
	if blobRef != ref {
		log.Printf("videothumbnail: access to %v forbidden; wrong blobref for handler", blobRef)
		http.Error(rw, "Forbidden.", 403)
		return
	}

	rw.Header().Set("Content-Type", "application/octet-stream")

	fr, err := schema.NewFileReader(fetcher, ref)
	if err != nil {
		httputil.ServeError(rw, req, err)
		return
	}
	defer fr.Close()

	http.ServeContent(rw, req, "", time.Now(), fr)
}

func (ih *ImageHandler) newFileReader(fileRef blob.Ref) (io.ReadCloser, error) {
	fi, ok := fileInfoPacked(ih.Search, ih.Fetcher, nil, fileRef)
	if debugPack {
		log.Printf("pkg/server/image.go: fileInfoPacked: ok=%v, %+v", ok, fi)
	}
	if ok {
		// This would be less gross if fileInfoPacked just
		// returned an io.ReadCloser, but then the download
		// handler would need more invasive changes for
		// ServeContent. So tolerate this for now.
		return struct {
			io.Reader
			io.Closer
		}{
			fi.rs,
			types.CloseFunc(fi.close),
		}, nil
	}
	// Default path, not going through blobpacked's fast path:
	return schema.NewFileReader(ih.Fetcher, fileRef)
}

func TestStorage(t *testing.T) {
	store, ref := storageAndBlobRef(t)
	fr, err := schema.NewFileReader(store, ref)
	if err != nil {
		t.Fatal(err)
	}
	inFile, err := os.Open(testFilepath)
	if err != nil {
		t.Fatal(err)
	}
	data, err := ioutil.ReadAll(inFile)
	if err != nil {
		t.Fatal(err)
	}
	bd, err := ioutil.ReadAll(fr)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(bd, data) {
		t.Error("expected to be the same")
	}
}

// vivify verifies that all the chunks for the file described by fileblob are on the blobserver.
// It makes a planned permanode, signs it, and uploads it. It finally makes a camliContent claim
// on that permanode for fileblob, signs it, and uploads it to the blobserver.
func vivify(blobReceiver blobserver.BlobReceiveConfiger, fileblob blob.SizedRef) error {
	sf, ok := blobReceiver.(blob.StreamingFetcher)
	if !ok {
		return fmt.Errorf("BlobReceiver is not a StreamingFetcher")
	}
	fetcher := blob.SeekerFromStreamingFetcher(sf)
	fr, err := schema.NewFileReader(fetcher, fileblob.Ref)
	if err != nil {
		return fmt.Errorf("Filereader error for blobref %v: %v", fileblob.Ref.String(), err)
	}
	defer fr.Close()

	h := sha1.New()
	n, err := io.Copy(h, fr)
	if err != nil {
		return fmt.Errorf("Could not read all file of blobref %v: %v", fileblob.Ref.String(), err)
	}
	if n != fr.Size() {
		return fmt.Errorf("Could not read all file of blobref %v. Wanted %v, got %v", fileblob.Ref.String(), fr.Size(), n)
	}

	config := blobReceiver.Config()
	if config == nil {
		return errors.New("blobReceiver has no config")
	}
	hf := config.HandlerFinder
	if hf == nil {
		return errors.New("blobReceiver config has no HandlerFinder")
	}
	JSONSignRoot, sh, err := hf.FindHandlerByType("jsonsign")
	if err != nil || sh == nil {
		return errors.New("jsonsign handler not found")
	}
	sigHelper, ok := sh.(*signhandler.Handler)
	if !ok {
		return errors.New("handler is not a JSON signhandler")
	}
	discoMap := sigHelper.DiscoveryMap(JSONSignRoot)
	publicKeyBlobRef, ok := discoMap["publicKeyBlobRef"].(string)
	if !ok {
		return fmt.Errorf("Discovery: json decoding error: %v", err)
	}

	// The file schema must have a modtime to vivify, as the modtime is used for all three of:
	// 1) the permanode's signature
	// 2) the camliContent attribute claim's "claimDate"
	// 3) the signature time of 2)
	claimDate, err := time.Parse(time.RFC3339, fr.FileSchema().UnixMtime)
	if err != nil {
		return fmt.Errorf("While parsing modtime for file %v: %v", fr.FileSchema().FileName, err)
	}

	permanodeBB := schema.NewHashPlannedPermanode(h)
	permanodeBB.SetSigner(blob.MustParse(publicKeyBlobRef))
	permanodeBB.SetClaimDate(claimDate)
	permanodeSigned, err := sigHelper.Sign(permanodeBB)
	if err != nil {
		return fmt.Errorf("Signing permanode %v: %v", permanodeSigned, err)
	}
	permanodeRef := blob.SHA1FromString(permanodeSigned)
	_, err = blobserver.ReceiveNoHash(blobReceiver, permanodeRef, strings.NewReader(permanodeSigned))
	if err != nil {
		return fmt.Errorf("While uploading signed permanode %v, %v: %v", permanodeRef, permanodeSigned, err)
	}

	contentClaimBB := schema.NewSetAttributeClaim(permanodeRef, "camliContent", fileblob.Ref.String())
	contentClaimBB.SetSigner(blob.MustParse(publicKeyBlobRef))
	contentClaimBB.SetClaimDate(claimDate)
	contentClaimSigned, err := sigHelper.Sign(contentClaimBB)
	if err != nil {
		return fmt.Errorf("Signing camliContent claim: %v", err)
	}
	contentClaimRef := blob.SHA1FromString(contentClaimSigned)
	_, err = blobserver.ReceiveNoHash(blobReceiver, contentClaimRef, strings.NewReader(contentClaimSigned))
	if err != nil {
		return fmt.Errorf("While uploading signed camliContent claim %v, %v: %v", contentClaimRef, contentClaimSigned, err)
	}
	return nil
}

func main() {
	client.AddFlags()
	flag.Parse()

	if *flagVersion {
		fmt.Fprintf(os.Stderr, "camget version: %s\n", buildinfo.Version())
		return
	}

	if *flagGraph && flag.NArg() != 1 {
		log.Fatalf("The --graph option requires exactly one parameter.")
	}

	var cl *client.Client
	var items []*blobref.BlobRef

	if *flagShared != "" {
		if client.ExplicitServer() != "" {
			log.Fatal("Can't use --shared with an explicit blobserver; blobserver is implicit from the --shared URL.")
		}
		if flag.NArg() != 0 {
			log.Fatal("No arguments permitted when using --shared")
		}
		cl1, target, err := client.NewFromShareRoot(*flagShared,
			client.OptionInsecure(*flagInsecureTLS))
		if err != nil {
			log.Fatal(err)
		}
		cl = cl1
		items = append(items, target)
	} else {
		cl = client.NewOrFail()
		for n := 0; n < flag.NArg(); n++ {
			arg := flag.Arg(n)
			br := blobref.Parse(arg)
			if br == nil {
				log.Fatalf("Failed to parse argument %q as a blobref.", arg)
			}
			items = append(items, br)
		}
	}

	cl.InsecureTLS = *flagInsecureTLS
	tr := cl.TransportForConfig(&client.TransportConfig{
		Verbose: *flagHTTP,
	})
	httpStats, _ := tr.(*httputil.StatsTransport)
	cl.SetHTTPClient(&http.Client{Transport: tr})

	diskCacheFetcher, err := cacher.NewDiskCache(cl)
	if err != nil {
		log.Fatalf("Error setting up local disk cache: %v", err)
	}
	defer diskCacheFetcher.Clean()
	if *flagVerbose {
		log.Printf("Using temp blob cache directory %s", diskCacheFetcher.Root)
	}

	for _, br := range items {
		if *flagGraph {
			printGraph(diskCacheFetcher, br)
			return
		}
		if *flagCheck {
			// TODO: do HEAD requests checking if the blobs exists.
			log.Fatal("not implemented")
			return
		}
		if *flagOutput == "-" {
			var rc io.ReadCloser
			var err error
			if *flagContents {
				rc, err = schema.NewFileReader(diskCacheFetcher, br)
				if err == nil {
					rc.(*schema.FileReader).LoadAllChunks()
				}
			} else {
				rc, err = fetch(diskCacheFetcher, br)
			}
			if err != nil {
				log.Fatal(err)
			}
			defer rc.Close()
			if _, err := io.Copy(os.Stdout, rc); err != nil {
				log.Fatalf("Failed reading %q: %v", br, err)
			}
		} else {
			if err := smartFetch(diskCacheFetcher, *flagOutput, br); err != nil {
				log.Fatal(err)
			}
		}
	}

	if *flagVerbose {
		log.Printf("HTTP requests: %d\n", httpStats.Requests())
	}
}

// smartFetch the things that blobs point to, not just blobs.
func smartFetch(src blobref.StreamingFetcher, targ string, br *blobref.BlobRef) error {
	rc, err := fetch(src, br)
	if err != nil {
		return err
	}
	defer rc.Close()

	sniffer := index.NewBlobSniffer(br)
	_, err = io.CopyN(sniffer, rc, sniffSize)
	if err != nil && err != io.EOF {
		return err
	}

	sniffer.Parse()
	blob, ok := sniffer.SchemaBlob()

	if !ok {
		if *flagVerbose {
			log.Printf("Fetching opaque data %v into %q", br, targ)
		}

		// opaque data - put it in a file
		f, err := os.Create(targ)
		if err != nil {
			return fmt.Errorf("opaque: %v", err)
		}
		defer f.Close()
		body, _ := sniffer.Body()
		r := io.MultiReader(bytes.NewReader(body), rc)
		_, err = io.Copy(f, r)
		return err
	}

	switch blob.Type() {
	case "directory":
		dir := filepath.Join(targ, blob.FileName())
		if *flagVerbose {
			log.Printf("Fetching directory %v into %s", br, dir)
		}
		if err := os.MkdirAll(dir, blob.FileMode()); err != nil {
			return err
		}
		if err := setFileMeta(dir, blob); err != nil {
			log.Print(err)
		}
		entries := blob.DirectoryEntries()
		if entries == nil {
			return fmt.Errorf("bad entries blobref in dir %v", blob.BlobRef())
		}
		return smartFetch(src, dir, entries)
	case "static-set":
		if *flagVerbose {
			log.Printf("Fetching directory entries %v into %s", br, targ)
		}

		// directory entries
		const numWorkers = 10
		type work struct {
			br   *blobref.BlobRef
			errc chan<- error
		}
		members := blob.StaticSetMembers()
		workc := make(chan work, len(members))
		defer close(workc)
		for i := 0; i < numWorkers; i++ {
			go func() {
				for wi := range workc {
					wi.errc <- smartFetch(src, targ, wi.br)
				}
			}()
		}
		var errcs []<-chan error
		for _, mref := range members {
			errc := make(chan error, 1)
			errcs = append(errcs, errc)
			workc <- work{mref, errc}
		}
		for _, errc := range errcs {
			if err := <-errc; err != nil {
				return err
			}
		}
		return nil
	case "file":
		seekFetcher := blobref.SeekerFromStreamingFetcher(src)
		fr, err := schema.NewFileReader(seekFetcher, br)
		if err != nil {
			return fmt.Errorf("NewFileReader: %v", err)
		}
		fr.LoadAllChunks()
		defer fr.Close()

		name := filepath.Join(targ, blob.FileName())

		if fi, err := os.Stat(name); err == nil && fi.Size() == fi.Size() {
			if *flagVerbose {
				log.Printf("Skipping %s; already exists.", name)
				return nil
			}
//.........这里部分代码省略.........

// vivify verifies that all the chunks for the file described by fileblob are on the blobserver.
// It makes a planned permanode, signs it, and uploads it. It finally makes a camliContent claim
// on that permanode for fileblob, signs it, and uploads it to the blobserver.
func vivify(blobReceiver blobserver.BlobReceiveConfiger, fileblob blobref.SizedBlobRef) error {
	sf, ok := blobReceiver.(blobref.StreamingFetcher)
	if !ok {
		return fmt.Errorf("BlobReceiver is not a StreamingFetcher")
	}
	fetcher := blobref.SeekerFromStreamingFetcher(sf)
	fr, err := schema.NewFileReader(fetcher, fileblob.BlobRef)
	if err != nil {
		return fmt.Errorf("Filereader error for blobref %v: %v", fileblob.BlobRef.String(), err)
	}
	defer fr.Close()

	h := sha1.New()
	n, err := io.Copy(h, fr)
	if err != nil {
		return fmt.Errorf("Could not read all file of blobref %v: %v", fileblob.BlobRef.String(), err)
	}
	if n != fr.Size() {
		return fmt.Errorf("Could not read all file of blobref %v. Wanted %v, got %v", fileblob.BlobRef.String(), fr.Size(), n)
	}

	config := blobReceiver.Config()
	if config == nil {
		return errors.New("blobReceiver has no config")
	}
	hf := config.HandlerFinder
	if hf == nil {
		return errors.New("blobReceiver config has no HandlerFinder")
	}
	JSONSignRoot, sh, err := hf.FindHandlerByType("jsonsign")
	// TODO(mpl): second check should not be necessary, and yet it happens. Figure it out.
	if err != nil || sh == nil {
		return errors.New("jsonsign handler not found")
	}
	sigHelper, ok := sh.(*signhandler.Handler)
	if !ok {
		return errors.New("handler is not a JSON signhandler")
	}
	discoMap := sigHelper.DiscoveryMap(JSONSignRoot)
	publicKeyBlobRef, ok := discoMap["publicKeyBlobRef"].(string)
	if !ok {
		return fmt.Errorf("Discovery: json decoding error: %v", err)
	}

	unsigned := schema.NewHashPlannedPermanode(h)
	unsigned["camliSigner"] = publicKeyBlobRef
	signed, err := sigHelper.SignMap(unsigned)
	if err != nil {
		return fmt.Errorf("Signing permanode %v: %v", signed, err)
	}
	signedPerm := blobref.SHA1FromString(signed)
	_, err = blobReceiver.ReceiveBlob(signedPerm, strings.NewReader(signed))
	if err != nil {
		return fmt.Errorf("While uploading signed permanode %v: %v", signed, err)
	}

	contentAttr := schema.NewSetAttributeClaim(signedPerm, "camliContent", fileblob.BlobRef.String())
	claimDate, err := time.Parse(time.RFC3339, fr.FileSchema().UnixMtime)
	contentAttr.SetClaimDate(claimDate)
	contentAttr["camliSigner"] = publicKeyBlobRef
	signed, err = sigHelper.SignMap(contentAttr)
	if err != nil {
		return fmt.Errorf("Signing camliContent claim: %v", err)
	}
	signedClaim := blobref.SHA1FromString(signed)
	_, err = blobReceiver.ReceiveBlob(signedClaim, strings.NewReader(signed))
	if err != nil {
		return fmt.Errorf("While uploading signed camliContent claim %v: %v", signed, err)
	}
	return nil
}

func (ih *ImageHandler) scaleImage(fileRef blob.Ref) (*formatAndImage, error) {
	fr, err := schema.NewFileReader(ih.Fetcher, fileRef)
	if err != nil {
		return nil, err
	}
	defer fr.Close()

	sr := types.NewStatsReader(imageBytesFetchedVar, fr)
	sr, conf, err := imageConfigFromReader(sr)
	if err != nil {
		return nil, err
	}

	// TODO(wathiede): build a size table keyed by conf.ColorModel for
	// common color models for a more exact size estimate.

	// This value is an estimate of the memory required to decode an image.
	// PNGs range from 1-64 bits per pixel (not all of which are supported by
	// the Go standard parser). JPEGs encoded in YCbCr 4:4:4 are 3 byte/pixel.
	// For all other JPEGs this is an overestimate.  For GIFs it is 3x larger
	// than needed.  How accurate this estimate is depends on the mix of
	// images being resized concurrently.
	ramSize := int64(conf.Width) * int64(conf.Height) * 3

	if err = ih.resizeSem.Acquire(ramSize); err != nil {
		return nil, err
	}
	defer ih.resizeSem.Release(ramSize)

	i, imConfig, err := images.Decode(sr, &images.DecodeOpts{
		MaxWidth:  ih.MaxWidth,
		MaxHeight: ih.MaxHeight,
	})
	if err != nil {
		return nil, err
	}
	b := i.Bounds()
	format := imConfig.Format

	isSquare := b.Dx() == b.Dy()
	if ih.Square && !isSquare {
		i = squareImage(i)
		b = i.Bounds()
	}

	// Encode as a new image
	var buf bytes.Buffer
	switch format {
	case "png":
		err = png.Encode(&buf, i)
	case "cr2":
		// Recompress CR2 files as JPEG
		format = "jpeg"
		fallthrough
	default:
		err = jpeg.Encode(&buf, i, &jpeg.Options{
			Quality: 90,
		})
	}
	if err != nil {
		return nil, err
	}

	return &formatAndImage{format: format, image: buf.Bytes()}, nil
}

func (dh *DownloadHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request, file *blobref.BlobRef) {
	if req.Method != "GET" && req.Method != "HEAD" {
		http.Error(rw, "Invalid download method", 400)
		return
	}

	fr, err := schema.NewFileReader(dh.storageSeekFetcher(), file)
	if err != nil {
		http.Error(rw, "Can't serve file: "+err.Error(), 500)
		return
	}
	defer fr.Close()

	schema := fr.FileSchema()
	rw.Header().Set("Content-Length", fmt.Sprintf("%d", schema.SumPartsSize()))

	mimeType, reader := magic.MimeTypeFromReader(fr)
	if dh.ForceMime != "" {
		mimeType = dh.ForceMime
	}
	if mimeType == "" {
		mimeType = "application/octet-stream"
	}
	rw.Header().Set("Content-Type", mimeType)
	if mimeType == "application/octet-stream" {
		// Chrome seems to silently do nothing on
		// application/octet-stream unless this is set.
		// Maybe it's confused by lack of URL it recognizes
		// along with lack of mime type?
		rw.Header().Set("Content-Disposition", "attachment; filename=file-"+file.String()+".dat")
	}

	if req.Method == "HEAD" {
		vbr := blobref.Parse(req.FormValue("verifycontents"))
		if vbr == nil {
			return
		}
		hash := vbr.Hash()
		if hash == nil {
			return
		}
		io.Copy(hash, reader) // ignore errors, caught later
		if vbr.HashMatches(hash) {
			rw.Header().Set("X-Camli-Contents", vbr.String())
		}
		return
	}

	n, err := io.Copy(rw, reader)
	log.Printf("For %q request of %s: copied %d, %v", req.Method, req.URL.Path, n, err)
	if err != nil {
		log.Printf("error serving download of file schema %s: %v", file, err)
		return
	}
	if size := schema.SumPartsSize(); n != int64(size) {
		log.Printf("error serving download of file schema %s: sent %d, expected size of %d",
			file, n, size)
		return
	}

}

// smartFetch the things that blobs point to, not just blobs.
func smartFetch(cl *client.Client, targ string, br *blobref.BlobRef) error {
	if *flagVerbose {
		log.Printf("Fetching %v into %q", br, targ)
	}

	rc, err := fetch(cl, br)
	if err != nil {
		return err
	}
	defer rc.Close()

	sniffer := new(index.BlobSniffer)
	_, err = io.CopyN(sniffer, rc, sniffSize)
	if err != nil && err != io.EOF {
		return err
	}

	sniffer.Parse()
	sc, ok := sniffer.Superset()

	if !ok {
		// opaque data - put it in a file
		f, err := os.Create(targ)
		if err != nil {
			return fmt.Errorf("opaque: %v", err)
		}
		defer f.Close()
		body, _ := sniffer.Body()
		r := io.MultiReader(bytes.NewBuffer(body), rc)
		_, err = io.Copy(f, r)
		return err
	}

	sc.BlobRef = br

	switch sc.Type {
	case "directory":
		dir := filepath.Join(targ, sc.FileName)
		if err := os.MkdirAll(dir, sc.FileMode()); err != nil {
			return err
		}
		if err := setFileMeta(dir, sc); err != nil {
			log.Print(err)
		}
		entries := blobref.Parse(sc.Entries)
		if entries == nil {
			return fmt.Errorf("bad entries blobref: %v", sc.Entries)
		}
		return smartFetch(cl, dir, entries)
	case "static-set":
		// directory entries
		for _, m := range sc.Members {
			dref := blobref.Parse(m)
			if dref == nil {
				return fmt.Errorf("bad member blobref: %v", m)
			}
			if err := smartFetch(cl, targ, dref); err != nil {
				return err
			}
		}
		return nil
	case "file":
		name := filepath.Join(targ, sc.FileName)
		f, err := os.Create(name)
		if err != nil {
			return fmt.Errorf("file type: %v", err)
		}
		defer f.Close()
		seekFetcher := blobref.SeekerFromStreamingFetcher(cl)
		fr, err := schema.NewFileReader(seekFetcher, br)
		if err != nil {
			return fmt.Errorf("NewFileReader: %v", err)
		}
		defer fr.Close()

		if err := setFileMeta(name, sc); err != nil {
			log.Print(err)
		}
		return nil
	default:
		return errors.New("unknown blob type: " + sc.Type)
	}
	panic("unreachable")
}