func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string, foreignSrc distribution.Descriptor, progressOutput progress.Output) (layer.Layer, error) {
	// We use system.OpenSequential to use sequential file access on Windows, avoiding
	// depleting the standby list. On Linux, this equates to a regular os.Open.
	rawTar, err := system.OpenSequential(filename)
	if err != nil {
		logrus.Debugf("Error reading embedded tar: %v", err)
		return nil, err
	}
	defer rawTar.Close()

	var r io.Reader
	if progressOutput != nil {
		fileInfo, err := rawTar.Stat()
		if err != nil {
			logrus.Debugf("Error statting file: %v", err)
			return nil, err
		}

		r = progress.NewProgressReader(rawTar, progressOutput, fileInfo.Size(), stringid.TruncateID(id), "Loading layer")
	} else {
		r = rawTar
	}

	inflatedLayerData, err := archive.DecompressStream(r)
	if err != nil {
		return nil, err
	}
	defer inflatedLayerData.Close()

	if ds, ok := l.ls.(layer.DescribableStore); ok {
		return ds.RegisterWithDescriptor(inflatedLayerData, rootFS.ChainID(), foreignSrc)
	}
	return l.ls.Register(inflatedLayerData, rootFS.ChainID())
}

func (pd *v2PushDescriptor) uploadUsingSession(
	ctx context.Context,
	progressOutput progress.Output,
	diffID layer.DiffID,
	layerUpload distribution.BlobWriter,
) (distribution.Descriptor, error) {
	arch, err := pd.layer.TarStream()
	if err != nil {
		return distribution.Descriptor{}, xfer.DoNotRetry{Err: err}
	}

	// don't care if this fails; best effort
	size, _ := pd.layer.DiffSize()

	reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, arch), progressOutput, size, pd.ID(), "Pushing")
	compressedReader, compressionDone := compress(reader)
	defer func() {
		reader.Close()
		<-compressionDone
	}()

	digester := digest.Canonical.New()
	tee := io.TeeReader(compressedReader, digester.Hash())

	nn, err := layerUpload.ReadFrom(tee)
	compressedReader.Close()
	if err != nil {
		return distribution.Descriptor{}, retryOnError(err)
	}

	pushDigest := digester.Digest()
	if _, err := layerUpload.Commit(ctx, distribution.Descriptor{Digest: pushDigest}); err != nil {
		return distribution.Descriptor{}, retryOnError(err)
	}

	logrus.Debugf("uploaded layer %s (%s), %d bytes", diffID, pushDigest, nn)
	progress.Update(progressOutput, pd.ID(), "Pushed")

	// Cache mapping from this layer's DiffID to the blobsum
	if err := pd.v2MetadataService.TagAndAdd(diffID, pd.hmacKey, metadata.V2Metadata{
		Digest:           pushDigest,
		SourceRepository: pd.repoInfo.FullName(),
	}); err != nil {
		return distribution.Descriptor{}, xfer.DoNotRetry{Err: err}
	}

	desc := distribution.Descriptor{
		Digest:    pushDigest,
		MediaType: schema2.MediaTypeLayer,
		Size:      nn,
	}

	pd.pushState.Lock()
	// If Commit succeeded, that's an indication that the remote registry speaks the v2 protocol.
	pd.pushState.confirmedV2 = true
	pd.pushState.remoteLayers[diffID] = desc
	pd.pushState.Unlock()

	return desc, nil
}

func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string, foreignSrc distribution.Descriptor, progressOutput progress.Output) (layer.Layer, error) {
	rawTar, err := os.Open(filename)
	if err != nil {
		logrus.Debugf("Error reading embedded tar: %v", err)
		return nil, err
	}
	defer rawTar.Close()

	var r io.Reader
	if progressOutput != nil {
		fileInfo, err := rawTar.Stat()
		if err != nil {
			logrus.Debugf("Error statting file: %v", err)
			return nil, err
		}

		r = progress.NewProgressReader(rawTar, progressOutput, fileInfo.Size(), stringid.TruncateID(id), "Loading layer")
	} else {
		r = rawTar
	}

	inflatedLayerData, err := archive.DecompressStream(r)
	if err != nil {
		return nil, err
	}
	defer inflatedLayerData.Close()

	if ds, ok := l.ls.(layer.DescribableStore); ok {
		return ds.RegisterWithDescriptor(inflatedLayerData, rootFS.ChainID(), foreignSrc)
	}
	return l.ls.Register(inflatedLayerData, rootFS.ChainID())
}

func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string, progressOutput progress.Output) (layer.Layer, error) {
	rawTar, err := os.Open(filename)
	if err != nil {
		logrus.Debugf("Error reading embedded tar: %v", err)
		return nil, err
	}
	defer rawTar.Close()

	inflatedLayerData, err := archive.DecompressStream(rawTar)
	if err != nil {
		return nil, err
	}
	defer inflatedLayerData.Close()

	if progressOutput != nil {
		fileInfo, err := os.Stat(filename)
		if err != nil {
			logrus.Debugf("Error statting file: %v", err)
			return nil, err
		}

		progressReader := progress.NewProgressReader(inflatedLayerData, progressOutput, fileInfo.Size(), stringid.TruncateID(id), "Loading layer")

		return l.ls.Register(progressReader, rootFS.ChainID())
	}
	return l.ls.Register(inflatedLayerData, rootFS.ChainID())
}

func (p *v1Pusher) pushImage(ctx context.Context, v1Image v1Image, ep string) (checksum string, err error) {
	l := v1Image.Layer()
	v1ID := v1Image.V1ID()
	truncID := stringid.TruncateID(l.DiffID().String())

	jsonRaw := v1Image.Config()
	progress.Update(p.config.ProgressOutput, truncID, "Pushing")

	// General rule is to use ID for graph accesses and compatibilityID for
	// calls to session.registry()
	imgData := &registry.ImgData{
		ID: v1ID,
	}

	// Send the json
	if err := p.session.PushImageJSONRegistry(imgData, jsonRaw, ep); err != nil {
		if err == registry.ErrAlreadyExists {
			progress.Update(p.config.ProgressOutput, truncID, "Image already pushed, skipping")
			return "", nil
		}
		return "", err
	}

	arch, err := l.TarStream()
	if err != nil {
		return "", err
	}
	defer arch.Close()

	// don't care if this fails; best effort
	size, _ := l.DiffSize()

	// Send the layer
	logrus.Debugf("rendered layer for %s of [%d] size", v1ID, size)

	reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, arch), p.config.ProgressOutput, size, truncID, "Pushing")
	defer reader.Close()

	checksum, checksumPayload, err := p.session.PushImageLayerRegistry(v1ID, reader, ep, jsonRaw)
	if err != nil {
		return "", err
	}
	imgData.Checksum = checksum
	imgData.ChecksumPayload = checksumPayload
	// Send the checksum
	if err := p.session.PushImageChecksumRegistry(imgData, ep); err != nil {
		return "", err
	}

	if err := p.v1IDService.Set(v1ID, p.repoInfo.Index.Name, l.DiffID()); err != nil {
		logrus.Warnf("Could not set v1 ID mapping: %v", err)
	}

	progress.Update(p.config.ProgressOutput, truncID, "Image successfully pushed")
	return imgData.Checksum, nil
}

// getContextFromURL uses a remote URL as context for a `docker build`. The
// remote resource is downloaded as either a Dockerfile or a tar archive.
// Returns the tar archive used for the context and a path of the
// dockerfile inside the tar.
func getContextFromURL(out io.Writer, remoteURL, dockerfileName string) (io.ReadCloser, string, error) {
	response, err := httputils.Download(remoteURL)
	if err != nil {
		return nil, "", fmt.Errorf("unable to download remote context %s: %v", remoteURL, err)
	}
	progressOutput := streamformatter.NewStreamFormatter().NewProgressOutput(out, true)

	// Pass the response body through a progress reader.
	progReader := progress.NewProgressReader(response.Body, progressOutput, response.ContentLength, "", fmt.Sprintf("Downloading build context from remote url: %s", remoteURL))

	return getContextFromReader(ioutils.NewReadCloserWrapper(progReader, func() error { return response.Body.Close() }), dockerfileName)
}

func (ld *v1LayerDescriptor) Download(ctx context.Context, progressOutput progress.Output) (io.ReadCloser, int64, error) {
	progress.Update(progressOutput, ld.ID(), "Pulling fs layer")
	layerReader, err := ld.session.GetRemoteImageLayer(ld.v1LayerID, ld.endpoint, ld.layerSize)
	if err != nil {
		progress.Update(progressOutput, ld.ID(), "Error pulling dependent layers")
		if uerr, ok := err.(*url.Error); ok {
			err = uerr.Err
		}
		if terr, ok := err.(net.Error); ok && terr.Timeout() {
			return nil, 0, err
		}
		return nil, 0, xfer.DoNotRetry{Err: err}
	}
	*ld.layersDownloaded = true

	ld.tmpFile, err = ioutil.TempFile("", "GetImageBlob")
	if err != nil {
		layerReader.Close()
		return nil, 0, err
	}

	reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, layerReader), progressOutput, ld.layerSize, ld.ID(), "Downloading")
	defer reader.Close()

	_, err = io.Copy(ld.tmpFile, reader)
	if err != nil {
		ld.Close()
		return nil, 0, err
	}

	progress.Update(progressOutput, ld.ID(), "Download complete")

	logrus.Debugf("Downloaded %s to tempfile %s", ld.ID(), ld.tmpFile.Name())

	ld.tmpFile.Seek(0, 0)

	// hand off the temporary file to the download manager, so it will only
	// be closed once
	tmpFile := ld.tmpFile
	ld.tmpFile = nil

	return ioutils.NewReadCloserWrapper(tmpFile, func() error {
		tmpFile.Close()
		err := os.RemoveAll(tmpFile.Name())
		if err != nil {
			logrus.Errorf("Failed to remove temp file: %s", tmpFile.Name())
		}
		return err
	}), ld.layerSize, nil
}

// Build implements Builder. It consumes the docker build API endpoint and sends
// a tar of the specified service build context.
func (d *DaemonBuilder) Build(imageName string, p *project.Project, service project.Service) error {
	if service.Config().Build == "" {
		return fmt.Errorf("Specified service does not have a build section")
	}

	ctx, err := CreateTar(p, service.Name())
	if err != nil {
		return err
	}
	defer ctx.Close()

	var progBuff io.Writer = os.Stdout
	var buildBuff io.Writer = os.Stdout

	// Setup an upload progress bar
	progressOutput := streamformatter.NewStreamFormatter().NewProgressOutput(progBuff, true)

	var body io.Reader = progress.NewProgressReader(ctx, progressOutput, 0, "", "Sending build context to Docker daemon")

	client := d.context.ClientFactory.Create(service)

	logrus.Infof("Building %s...", imageName)

	outFd, isTerminalOut := term.GetFdInfo(os.Stdout)

	response, err := client.ImageBuild(context.Background(), types.ImageBuildOptions{
		Context:     body,
		Tags:        []string{imageName},
		NoCache:     d.context.NoCache,
		Remove:      true,
		Dockerfile:  service.Config().Dockerfile,
		AuthConfigs: d.context.ConfigFile.AuthConfigs,
	})

	err = jsonmessage.DisplayJSONMessagesStream(response.Body, buildBuff, outFd, isTerminalOut, nil)
	if err != nil {
		if jerr, ok := err.(*jsonmessage.JSONError); ok {
			// If no error code is set, default to 1
			if jerr.Code == 0 {
				jerr.Code = 1
			}
			fmt.Fprintf(os.Stderr, "%s%s", progBuff, buildBuff)
			return fmt.Errorf("Status: %s, Code: %d", jerr.Message, jerr.Code)
		}
	}
	return err
}

// WriteImageBlobs writes the image blob to the storage layer
func WriteImageBlobs(images []*ImageWithMeta) error {
	if options.standalone {
		return nil
	}

	// iterate from parent to children
	// so that portlayer can extract each layer
	// on top of previous one
	destination := DestinationDirectory()
	for i := len(images) - 1; i >= 0; i-- {
		image := images[i]

		id := image.Image.ID
		f, err := os.Open(path.Join(destination, id, id+".tar"))
		if err != nil {
			return fmt.Errorf("Failed to open file: %s", err)
		}
		defer f.Close()

		fi, err := f.Stat()
		if err != nil {
			return fmt.Errorf("Failed to stat file: %s", err)
		}

		in := progress.NewProgressReader(
			ioutils.NewCancelReadCloser(context.Background(), f),
			po,
			fi.Size(),
			image.String(),
			"Extracting",
		)
		defer in.Close()

		// Write the image
		err = WriteImage(image, in)
		if err != nil {
			return fmt.Errorf("Failed to write to image store: %s", err)
		}
		progress.Update(po, image.String(), "Pull complete")
	}
	if err := os.RemoveAll(destination); err != nil {
		return fmt.Errorf("Failed to remove download directory: %s", err)
	}
	return nil
}

// Build implements Builder. It consumes the docker build API endpoint and sends
// a tar of the specified service build context.
func (d *DaemonBuilder) Build(ctx context.Context, imageName string) error {
	buildCtx, err := createTar(d.ContextDirectory, d.Dockerfile)
	if err != nil {
		return err
	}
	defer buildCtx.Close()

	var progBuff io.Writer = os.Stdout
	var buildBuff io.Writer = os.Stdout

	// Setup an upload progress bar
	progressOutput := streamformatter.NewStreamFormatter().NewProgressOutput(progBuff, true)

	var body io.Reader = progress.NewProgressReader(buildCtx, progressOutput, 0, "", "Sending build context to Docker daemon")

	logrus.Infof("Building %s...", imageName)

	outFd, isTerminalOut := term.GetFdInfo(os.Stdout)

	response, err := d.Client.ImageBuild(ctx, body, types.ImageBuildOptions{
		Tags:        []string{imageName},
		NoCache:     d.NoCache,
		Remove:      true,
		ForceRemove: d.ForceRemove,
		PullParent:  d.Pull,
		Dockerfile:  d.Dockerfile,
		AuthConfigs: d.AuthConfigs,
	})
	if err != nil {
		return err
	}

	err = jsonmessage.DisplayJSONMessagesStream(response.Body, buildBuff, outFd, isTerminalOut, nil)
	if err != nil {
		if jerr, ok := err.(*jsonmessage.JSONError); ok {
			// If no error code is set, default to 1
			if jerr.Code == 0 {
				jerr.Code = 1
			}
			return fmt.Errorf("Status: %s, Code: %d", jerr.Message, jerr.Code)
		}
	}
	return err
}

// fetch fetches the given URL using ctxhttp. It also streams back the progress bar only when ID is not an empty string.
func (u *URLFetcher) fetchToFile(ctx context.Context, url *url.URL, ID string, po progress.Output) (string, error) {
	rdr, hdrs, err := u.fetch(ctx, url, ID)
	if err != nil {
		return "", err
	}
	defer rdr.Close()

	// stream progress as json and body into a file - only if we have an ID and a Content-Length header
	if contLen := hdrs.Get("Content-Length"); ID != "" && contLen != "" {
		cl, cerr := strconv.ParseInt(contLen, 10, 64)
		if cerr != nil {
			return "", cerr
		}

		if po != nil {
			rdr = progress.NewProgressReader(
				ioutils.NewCancelReadCloser(ctx, rdr), po, cl, ID, "Downloading",
			)
			defer rdr.Close()
		} else {
			rdr = ioutils.NewCancelReadCloser(ctx, rdr)
		}
	}

	// Create a temporary file and stream the res.Body into it
	out, err := ioutil.TempFile(os.TempDir(), ID)
	if err != nil {
		return "", DoNotRetry{Err: err}
	}
	defer out.Close()

	// Stream into it
	_, err = io.Copy(out, rdr)
	if err != nil {
		log.Errorf("Fetch (%s) to file failed to stream to file: %s", url.String(), err)

		// cleanup
		defer os.Remove(out.Name())
		return "", DoNotRetry{Err: err}
	}

	// Return the temporary file name
	return out.Name(), nil
}

// WriteImageBlob writes the image blob to the storage layer
func (ic *ImageC) WriteImageBlob(image *ImageWithMeta, progressOutput progress.Output, cleanup bool) error {
	defer trace.End(trace.Begin(image.Image.ID))

	destination := DestinationDirectory(ic.Options)

	id := image.Image.ID
	log.Infof("Path: %s", path.Join(destination, id, id+".targ"))
	f, err := os.Open(path.Join(destination, id, id+".tar"))
	if err != nil {
		return fmt.Errorf("Failed to open file: %s", err)
	}
	defer f.Close()

	fi, err := f.Stat()
	if err != nil {
		return fmt.Errorf("Failed to stat file: %s", err)
	}

	in := progress.NewProgressReader(
		ioutils.NewCancelReadCloser(context.Background(), f),
		progressOutput,
		fi.Size(),
		image.String(),
		"Extracting",
	)
	defer in.Close()

	// Write the image
	err = WriteImage(ic.Host, image, in)
	if err != nil {
		return fmt.Errorf("Failed to write to image store: %s", err)
	}

	progress.Update(progressOutput, image.String(), "Pull complete")

	if cleanup {
		if err := os.RemoveAll(destination); err != nil {
			return fmt.Errorf("Failed to remove download directory: %s", err)
		}
	}
	return nil
}

func (ld *v1LayerDescriptor) Download(ctx context.Context, progressOutput progress.Output) (io.ReadCloser, int64, error) {
	progress.Update(progressOutput, ld.ID(), "Pulling fs layer")
	layerReader, err := ld.session.GetRemoteImageLayer(ld.v1LayerID, ld.endpoint, ld.layerSize)
	if err != nil {
		progress.Update(progressOutput, ld.ID(), "Error pulling dependent layers")
		if uerr, ok := err.(*url.Error); ok {
			err = uerr.Err
		}
		if terr, ok := err.(net.Error); ok && terr.Timeout() {
			return nil, 0, err
		}
		return nil, 0, xfer.DoNotRetry{Err: err}
	}
	*ld.layersDownloaded = true

	ld.tmpFile, err = ioutil.TempFile("", "GetImageBlob")
	if err != nil {
		layerReader.Close()
		return nil, 0, err
	}

	reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, layerReader), progressOutput, ld.layerSize, ld.ID(), "Downloading")
	defer reader.Close()

	_, err = io.Copy(ld.tmpFile, reader)
	if err != nil {
		ld.Close()
		return nil, 0, err
	}

	progress.Update(progressOutput, ld.ID(), "Download complete")

	logrus.Debugf("Downloaded %s to tempfile %s", ld.ID(), ld.tmpFile.Name())

	ld.tmpFile.Seek(0, 0)
	return ld.tmpFile, ld.layerSize, nil
}

// ImportImage imports an image, getting the archived layer data either from
// inConfig (if src is "-"), or from a URI specified in src. Progress output is
// written to outStream. Repository and tag names can optionally be given in
// the repo and tag arguments, respectively.
func (daemon *Daemon) ImportImage(src string, repository, tag string, msg string, inConfig io.ReadCloser, outStream io.Writer, changes []string) error {
	var (
		sf     = streamformatter.NewJSONStreamFormatter()
		rc     io.ReadCloser
		resp   *http.Response
		newRef reference.Named
	)

	if repository != "" {
		var err error
		newRef, err = reference.ParseNamed(repository)
		if err != nil {
			return err
		}

		if _, isCanonical := newRef.(reference.Canonical); isCanonical {
			return errors.New("cannot import digest reference")
		}

		if tag != "" {
			newRef, err = reference.WithTag(newRef, tag)
			if err != nil {
				return err
			}
		}
	}

	config, err := dockerfile.BuildFromConfig(&container.Config{}, changes)
	if err != nil {
		return err
	}
	if src == "-" {
		rc = inConfig
	} else {
		inConfig.Close()
		u, err := url.Parse(src)
		if err != nil {
			return err
		}
		if u.Scheme == "" {
			u.Scheme = "http"
			u.Host = src
			u.Path = ""
		}
		outStream.Write(sf.FormatStatus("", "Downloading from %s", u))
		resp, err = httputils.Download(u.String())
		if err != nil {
			return err
		}
		progressOutput := sf.NewProgressOutput(outStream, true)
		rc = progress.NewProgressReader(resp.Body, progressOutput, resp.ContentLength, "", "Importing")
	}

	defer rc.Close()
	if len(msg) == 0 {
		msg = "Imported from " + src
	}

	inflatedLayerData, err := archive.DecompressStream(rc)
	if err != nil {
		return err
	}
	// TODO: support windows baselayer?
	l, err := daemon.layerStore.Register(inflatedLayerData, "")
	if err != nil {
		return err
	}
	defer layer.ReleaseAndLog(daemon.layerStore, l)

	created := time.Now().UTC()
	imgConfig, err := json.Marshal(&image.Image{
		V1Image: image.V1Image{
			DockerVersion: dockerversion.Version,
			Config:        config,
			Architecture:  runtime.GOARCH,
			OS:            runtime.GOOS,
			Created:       created,
			Comment:       msg,
		},
		RootFS: &image.RootFS{
			Type:    "layers",
			DiffIDs: []layer.DiffID{l.DiffID()},
		},
		History: []image.History{{
			Created: created,
			Comment: msg,
		}},
	})
	if err != nil {
		return err
	}

	id, err := daemon.imageStore.Create(imgConfig)
	if err != nil {
		return err
	}
//.........这里部分代码省略.........

// Build will build all images in the Parity setup
func (c *DockerCompose) Build() error {
	log.Stage("Bulding containers")
	base := "Dockerfile"
	cwd, _ := os.Getwd()
	baseVersion := c.generateContainerVersion(cwd, base)
	imageName := fmt.Sprintf("%s:%s", c.ImageName, baseVersion)
	client, _ := dockerclient2.NewEnvClient()

	log.Step("Checking if image %s exists locally", imageName)
	if images, err := client.ImageList(context.Background(), types.ImageListOptions{MatchName: imageName}); err == nil {
		for _, i := range images {
			log.Info("Found image: %s", i.ID)
			return nil
		}
	}

	log.Step("Image %s not found locally, pulling", imageName)
	client.ImagePull(context.Background(), types.ImagePullOptions{ImageID: imageName}, nil)

	log.Step("Image %s not found anywhere, building", imageName)

	ctx, err := c.CreateTar(".", "Dockerfile")
	if err != nil {
		return err
	}
	defer ctx.Close()

	var progBuff io.Writer = os.Stdout
	var buildBuff io.Writer = os.Stdout

	// Setup an upload progress bar
	progressOutput := streamformatter.NewStreamFormatter().NewProgressOutput(progBuff, true)

	var body io.Reader = progress.NewProgressReader(ctx, progressOutput, 0, "", "Sending build context to Docker daemon")

	logrus.Infof("Building %s...", imageName)

	outFd, isTerminalOut := term.GetFdInfo(os.Stdout)

	// Publish latest and specific version
	response, err := client.ImageBuild(context.Background(), types.ImageBuildOptions{
		Context:    body,
		Tags:       []string{imageName, fmt.Sprintf("%s:latest", c.ImageName)},
		NoCache:    false,
		Remove:     true,
		Dockerfile: "Dockerfile",
	})

	if err != nil {
		log.Error(err.Error())
		return err
	}

	err = jsonmessage.DisplayJSONMessagesStream(response.Body, buildBuff, outFd, isTerminalOut, nil)
	if err != nil {
		if jerr, ok := err.(*jsonmessage.JSONError); ok {
			// If no error code is set, default to 1
			if jerr.Code == 0 {
				jerr.Code = 1
			}
			fmt.Fprintf(os.Stderr, "%s%s", progBuff, buildBuff)
			return fmt.Errorf("Status: %s, Code: %d", jerr.Message, jerr.Code)
		}
	}

	return err
}

//.........这里部分代码省略.........
				default:
				}

				retries++
				if _, isDNR := err.(DoNotRetry); isDNR || retries == maxDownloadAttempts {
					logrus.Errorf("Download failed: %v", err)
					d.err = err
					return
				}

				logrus.Errorf("Download failed, retrying: %v", err)
				delay := retries * 5
				ticker := time.NewTicker(time.Second)

			selectLoop:
				for {
					progress.Updatef(progressOutput, descriptor.ID(), "Retrying in %d second%s", delay, (map[bool]string{true: "s"})[delay != 1])
					select {
					case <-ticker.C:
						delay--
						if delay == 0 {
							ticker.Stop()
							break selectLoop
						}
					case <-d.Transfer.Context().Done():
						ticker.Stop()
						d.err = errors.New("download cancelled during retry delay")
						return
					}

				}
			}

			close(inactive)

			if parentDownload != nil {
				select {
				case <-d.Transfer.Context().Done():
					d.err = errors.New("layer registration cancelled")
					downloadReader.Close()
					return
				case <-parentDownload.Done():
				}

				l, err := parentDownload.result()
				if err != nil {
					d.err = err
					downloadReader.Close()
					return
				}
				parentLayer = l.ChainID()
			}

			reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(d.Transfer.Context(), downloadReader), progressOutput, size, descriptor.ID(), "Extracting")
			defer reader.Close()

			inflatedLayerData, err := archive.DecompressStream(reader)
			if err != nil {
				d.err = fmt.Errorf("could not get decompression stream: %v", err)
				return
			}

			var src distribution.Descriptor
			if fs, ok := descriptor.(distribution.Describable); ok {
				src = fs.Descriptor()
			}
			if ds, ok := d.layerStore.(layer.DescribableStore); ok {
				d.layer, err = ds.RegisterWithDescriptor(inflatedLayerData, parentLayer, src)
			} else {
				d.layer, err = d.layerStore.Register(inflatedLayerData, parentLayer)
			}
			if err != nil {
				select {
				case <-d.Transfer.Context().Done():
					d.err = errors.New("layer registration cancelled")
				default:
					d.err = fmt.Errorf("failed to register layer: %v", err)
				}
				return
			}

			progress.Update(progressOutput, descriptor.ID(), "Pull complete")
			withRegistered, hasRegistered := descriptor.(DownloadDescriptorWithRegistered)
			if hasRegistered {
				withRegistered.Registered(d.layer.DiffID())
			}

			// Doesn't actually need to be its own goroutine, but
			// done like this so we can defer close(c).
			go func() {
				<-d.Transfer.Released()
				if d.layer != nil {
					layer.ReleaseAndLog(d.layerStore, d.layer)
				}
			}()
		}()

		return d
	}
}

func (b *Builder) download(srcURL string) (fi builder.FileInfo, err error) {
	// get filename from URL
	u, err := url.Parse(srcURL)
	if err != nil {
		return
	}
	path := filepath.FromSlash(u.Path) // Ensure in platform semantics
	if strings.HasSuffix(path, string(os.PathSeparator)) {
		path = path[:len(path)-1]
	}
	parts := strings.Split(path, string(os.PathSeparator))
	filename := parts[len(parts)-1]
	if filename == "" {
		err = fmt.Errorf("cannot determine filename from url: %s", u)
		return
	}

	// Initiate the download
	resp, err := httputils.Download(srcURL)
	if err != nil {
		return
	}

	// Prepare file in a tmp dir
	tmpDir, err := ioutils.TempDir("", "docker-remote")
	if err != nil {
		return
	}
	defer func() {
		if err != nil {
			os.RemoveAll(tmpDir)
		}
	}()
	tmpFileName := filepath.Join(tmpDir, filename)
	tmpFile, err := os.OpenFile(tmpFileName, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
	if err != nil {
		return
	}

	stdoutFormatter := b.Stdout.(*streamformatter.StdoutFormatter)
	progressOutput := stdoutFormatter.StreamFormatter.NewProgressOutput(stdoutFormatter.Writer, true)
	progressReader := progress.NewProgressReader(resp.Body, progressOutput, resp.ContentLength, "", "Downloading")
	// Download and dump result to tmp file
	if _, err = io.Copy(tmpFile, progressReader); err != nil {
		tmpFile.Close()
		return
	}
	fmt.Fprintln(b.Stdout)
	// ignoring error because the file was already opened successfully
	tmpFileSt, err := tmpFile.Stat()
	if err != nil {
		return
	}
	tmpFile.Close()

	// Set the mtime to the Last-Modified header value if present
	// Otherwise just remove atime and mtime
	mTime := time.Time{}

	lastMod := resp.Header.Get("Last-Modified")
	if lastMod != "" {
		// If we can't parse it then just let it default to 'zero'
		// otherwise use the parsed time value
		if parsedMTime, err := http.ParseTime(lastMod); err == nil {
			mTime = parsedMTime
		}
	}

	if err = system.Chtimes(tmpFileName, mTime, mTime); err != nil {
		return
	}

	// Calc the checksum, even if we're using the cache
	r, err := archive.Tar(tmpFileName, archive.Uncompressed)
	if err != nil {
		return
	}
	tarSum, err := tarsum.NewTarSum(r, true, tarsum.Version1)
	if err != nil {
		return
	}
	if _, err = io.Copy(ioutil.Discard, tarSum); err != nil {
		return
	}
	hash := tarSum.Sum(nil)
	r.Close()
	return &builder.HashedFileInfo{FileInfo: builder.PathFileInfo{FileInfo: tmpFileSt, FilePath: tmpFileName}, FileHash: hash}, nil
}

func (ld *v2LayerDescriptor) Download(ctx context.Context, progressOutput progress.Output) (io.ReadCloser, int64, error) {
	logrus.Debugf("pulling blob %q", ld.digest)

	blobs := ld.repo.Blobs(ctx)

	layerDownload, err := blobs.Open(ctx, ld.digest)
	if err != nil {
		logrus.Debugf("Error statting layer: %v", err)
		if err == distribution.ErrBlobUnknown {
			return nil, 0, xfer.DoNotRetry{Err: err}
		}
		return nil, 0, retryOnError(err)
	}

	size, err := layerDownload.Seek(0, os.SEEK_END)
	if err != nil {
		// Seek failed, perhaps because there was no Content-Length
		// header. This shouldn't fail the download, because we can
		// still continue without a progress bar.
		size = 0
	} else {
		// Restore the seek offset at the beginning of the stream.
		_, err = layerDownload.Seek(0, os.SEEK_SET)
		if err != nil {
			return nil, 0, err
		}
	}

	reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, layerDownload), progressOutput, size, ld.ID(), "Downloading")
	defer reader.Close()

	verifier, err := digest.NewDigestVerifier(ld.digest)
	if err != nil {
		return nil, 0, xfer.DoNotRetry{Err: err}
	}

	tmpFile, err := ioutil.TempFile("", "GetImageBlob")
	if err != nil {
		return nil, 0, xfer.DoNotRetry{Err: err}
	}

	_, err = io.Copy(tmpFile, io.TeeReader(reader, verifier))
	if err != nil {
		return nil, 0, retryOnError(err)
	}

	progress.Update(progressOutput, ld.ID(), "Verifying Checksum")

	if !verifier.Verified() {
		err = fmt.Errorf("filesystem layer verification failed for digest %s", ld.digest)
		logrus.Error(err)
		tmpFile.Close()
		if err := os.RemoveAll(tmpFile.Name()); err != nil {
			logrus.Errorf("Failed to remove temp file: %s", tmpFile.Name())
		}

		return nil, 0, xfer.DoNotRetry{Err: err}
	}

	progress.Update(progressOutput, ld.ID(), "Download complete")

	logrus.Debugf("Downloaded %s to tempfile %s", ld.ID(), tmpFile.Name())

	tmpFile.Seek(0, 0)
	return ioutils.NewReadCloserWrapper(tmpFile, tmpFileCloser(tmpFile)), size, nil
}

func (pd *v2PushDescriptor) Upload(ctx context.Context, progressOutput progress.Output) (digest.Digest, error) {
	diffID := pd.DiffID()

	logrus.Debugf("Pushing layer: %s", diffID)

	// Do we have any blobsums associated with this layer's DiffID?
	possibleBlobsums, err := pd.blobSumService.GetBlobSums(diffID)
	if err == nil {
		dgst, exists, err := blobSumAlreadyExists(ctx, possibleBlobsums, pd.repo, pd.layersPushed)
		if err != nil {
			progress.Update(progressOutput, pd.ID(), "Image push failed")
			return "", retryOnError(err)
		}
		if exists {
			progress.Update(progressOutput, pd.ID(), "Layer already exists")
			return dgst, nil
		}
	}

	// if digest was empty or not saved, or if blob does not exist on the remote repository,
	// then push the blob.
	bs := pd.repo.Blobs(ctx)

	// Send the layer
	layerUpload, err := bs.Create(ctx)
	if err != nil {
		return "", retryOnError(err)
	}
	defer layerUpload.Close()

	arch, err := pd.layer.TarStream()
	if err != nil {
		return "", xfer.DoNotRetry{Err: err}
	}

	// don't care if this fails; best effort
	size, _ := pd.layer.DiffSize()

	reader := progress.NewProgressReader(ioutils.NewCancelReadCloser(ctx, arch), progressOutput, size, pd.ID(), "Pushing")
	defer reader.Close()
	compressedReader := compress(reader)

	digester := digest.Canonical.New()
	tee := io.TeeReader(compressedReader, digester.Hash())

	nn, err := layerUpload.ReadFrom(tee)
	compressedReader.Close()
	if err != nil {
		return "", retryOnError(err)
	}

	pushDigest := digester.Digest()
	if _, err := layerUpload.Commit(ctx, distribution.Descriptor{Digest: pushDigest}); err != nil {
		return "", retryOnError(err)
	}

	// If Commit succeded, that's an indication that the remote registry
	// speaks the v2 protocol.
	*pd.confirmedV2 = true

	logrus.Debugf("uploaded layer %s (%s), %d bytes", diffID, pushDigest, nn)
	progress.Update(progressOutput, pd.ID(), "Pushed")

	// Cache mapping from this layer's DiffID to the blobsum
	if err := pd.blobSumService.Add(diffID, pushDigest); err != nil {
		return "", xfer.DoNotRetry{Err: err}
	}

	pd.layersPushed.Lock()
	pd.layersPushed.layersPushed[pushDigest] = true
	pd.layersPushed.Unlock()

	return pushDigest, nil
}

// ImportImage imports an image, getting the archived layer data either from
// inConfig (if src is "-"), or from a URI specified in src. Progress output is
// written to outStream. Repository and tag names can optionally be given in
// the repo and tag arguments, respectively.
func (daemon *Daemon) ImportImage(src string, newRef reference.Named, msg string, inConfig io.ReadCloser, outStream io.Writer, config *runconfig.Config) error {
	var (
		sf      = streamformatter.NewJSONStreamFormatter()
		archive io.ReadCloser
		resp    *http.Response
	)

	if src == "-" {
		archive = inConfig
	} else {
		inConfig.Close()
		u, err := url.Parse(src)
		if err != nil {
			return err
		}
		if u.Scheme == "" {
			u.Scheme = "http"
			u.Host = src
			u.Path = ""
		}
		outStream.Write(sf.FormatStatus("", "Downloading from %s", u))
		resp, err = httputils.Download(u.String())
		if err != nil {
			return err
		}
		progressOutput := sf.NewProgressOutput(outStream, true)
		archive = progress.NewProgressReader(resp.Body, progressOutput, resp.ContentLength, "", "Importing")
	}

	defer archive.Close()
	if len(msg) == 0 {
		msg = "Imported from " + src
	}
	// TODO: support windows baselayer?
	l, err := daemon.layerStore.Register(archive, "")
	if err != nil {
		return err
	}
	defer layer.ReleaseAndLog(daemon.layerStore, l)

	created := time.Now().UTC()
	imgConfig, err := json.Marshal(&image.Image{
		V1Image: image.V1Image{
			DockerVersion: dockerversion.Version,
			Config:        config,
			Architecture:  runtime.GOARCH,
			OS:            runtime.GOOS,
			Created:       created,
			Comment:       msg,
		},
		RootFS: &image.RootFS{
			Type:    "layers",
			DiffIDs: []layer.DiffID{l.DiffID()},
		},
		History: []image.History{{
			Created: created,
			Comment: msg,
		}},
	})
	if err != nil {
		return err
	}

	id, err := daemon.imageStore.Create(imgConfig)
	if err != nil {
		return err
	}

	// FIXME: connect with commit code and call refstore directly
	if newRef != nil {
		if err := daemon.TagImage(newRef, id.String()); err != nil {
			return err
		}
	}

	outStream.Write(sf.FormatStatus("", id.String()))
	daemon.EventsService.Log("import", id.String(), "")
	return nil
}