func WriteStatus(requestedTag string, out io.Writer, sf *streamformatter.StreamFormatter, layersDownloaded bool) {
	if layersDownloaded {
		out.Write(sf.FormatStatus("", "Status: Downloaded newer image for %s", requestedTag))
	} else {
		out.Write(sf.FormatStatus("", "Status: Image is up to date for %s", requestedTag))
	}
}

// NewImageC returns a new instance of ImageC
func NewImageC(options Options, strfmtr *streamformatter.StreamFormatter) *ImageC {
	return &ImageC{
		Options:        options,
		sf:             strfmtr,
		progressOutput: strfmtr.NewProgressOutput(options.Outstream, false),
	}
}

func (s *TagStore) pushImageToEndpoint(endpoint string, out io.Writer, remoteName string, imageIDs []string,
	tags map[string][]string, repo *registry.RepositoryData, sf *streamformatter.StreamFormatter, r *registry.Session) error {
	workerCount := len(imageIDs)
	// start a maximum of 5 workers to check if images exist on the specified endpoint.
	if workerCount > 5 {
		workerCount = 5
	}
	var (
		wg           = &sync.WaitGroup{}
		imageData    = make(chan imagePushData, workerCount*2)
		imagesToPush = make(chan string, workerCount*2)
		pushes       = make(chan map[string]struct{}, 1)
	)
	for i := 0; i < workerCount; i++ {
		wg.Add(1)
		go lookupImageOnEndpoint(wg, r, out, sf, imageData, imagesToPush)
	}
	// start a go routine that consumes the images to push
	go func() {
		shouldPush := make(map[string]struct{})
		for id := range imagesToPush {
			shouldPush[id] = struct{}{}
		}
		pushes <- shouldPush
	}()
	for _, id := range imageIDs {
		imageData <- imagePushData{
			id:       id,
			endpoint: endpoint,
			tokens:   repo.Tokens,
		}
	}
	// close the channel to notify the workers that there will be no more images to check.
	close(imageData)
	wg.Wait()
	close(imagesToPush)
	// wait for all the images that require pushes to be collected into a consumable map.
	shouldPush := <-pushes
	// finish by pushing any images and tags to the endpoint.  The order that the images are pushed
	// is very important that is why we are still iterating over the ordered list of imageIDs.
	for _, id := range imageIDs {
		if _, push := shouldPush[id]; push {
			if _, err := s.pushImage(r, out, id, endpoint, repo.Tokens, sf); err != nil {
				// FIXME: Continue on error?
				return err
			}
		}
		for _, tag := range tags[id] {
			out.Write(sf.FormatStatus("", "Pushing tag for rev [%s] on {%s}", stringid.TruncateID(id), endpoint+"repositories/"+remoteName+"/tags/"+tag))
			if err := r.PushRegistryTag(remoteName, id, tag, endpoint); err != nil {
				return err
			}
		}
	}
	return nil
}

// lookupImageOnEndpoint checks the specified endpoint to see if an image exists
// and if it is absent then it sends the image id to the channel to be pushed.
func lookupImageOnEndpoint(wg *sync.WaitGroup, r *registry.Session, out io.Writer, sf *streamformatter.StreamFormatter,
	images chan imagePushData, imagesToPush chan string) {
	defer wg.Done()
	for image := range images {
		if err := r.LookupRemoteImage(image.id, image.endpoint); err != nil {
			logrus.Errorf("Error in LookupRemoteImage: %s", err)
			imagesToPush <- image.id
			continue
		}
		out.Write(sf.FormatStatus("", "Image %s already pushed, skipping", stringid.TruncateID(image.id)))
	}
}

// pushRepository pushes layers that do not already exist on the registry.
func (s *TagStore) pushRepository(r *registry.Session, out io.Writer,
	repoInfo *registry.RepositoryInfo, localRepo map[string]string,
	tag string, sf *streamformatter.StreamFormatter) error {
	logrus.Debugf("Local repo: %s", localRepo)
	out = ioutils.NewWriteFlusher(out)
	imgList, tags, err := s.getImageList(localRepo, tag)
	if err != nil {
		return err
	}
	out.Write(sf.FormatStatus("", "Sending image list"))

	imageIndex := s.createImageIndex(imgList, tags)
	logrus.Debugf("Preparing to push %s with the following images and tags", localRepo)
	for _, data := range imageIndex {
		logrus.Debugf("Pushing ID: %s with Tag: %s", data.ID, data.Tag)
	}
	// Register all the images in a repository with the registry
	// If an image is not in this list it will not be associated with the repository
	repoData, err := r.PushImageJSONIndex(repoInfo.RemoteName, imageIndex, false, nil)
	if err != nil {
		return err
	}
	nTag := 1
	if tag == "" {
		nTag = len(localRepo)
	}
	out.Write(sf.FormatStatus("", "Pushing repository %s (%d tags)", repoInfo.CanonicalName, nTag))
	// push the repository to each of the endpoints only if it does not exist.
	for _, endpoint := range repoData.Endpoints {
		if err := s.pushImageToEndpoint(endpoint, out, repoInfo.RemoteName, imgList, tags, repoData, sf, r); err != nil {
			return err
		}
	}
	_, err = r.PushImageJSONIndex(repoInfo.RemoteName, imageIndex, true, repoData.Endpoints)
	return err
}

func (s *TagStore) pushImage(r *registry.Session, out io.Writer, imgID, ep string, token []string, sf *streamformatter.StreamFormatter) (checksum string, err error) {
	out = ioutils.NewWriteFlusher(out)
	jsonRaw, err := s.graph.RawJSON(imgID)
	if err != nil {
		return "", fmt.Errorf("Cannot retrieve the path for {%s}: %s", imgID, err)
	}
	out.Write(sf.FormatProgress(stringid.TruncateID(imgID), "Pushing", nil))

	imgData := &registry.ImgData{
		ID: imgID,
	}

	// Send the json
	if err := r.PushImageJSONRegistry(imgData, jsonRaw, ep); err != nil {
		if err == registry.ErrAlreadyExists {
			out.Write(sf.FormatProgress(stringid.TruncateID(imgData.ID), "Image already pushed, skipping", nil))
			return "", nil
		}
		return "", err
	}

	layerData, err := s.graph.TempLayerArchive(imgID, sf, out)
	if err != nil {
		return "", fmt.Errorf("Failed to generate layer archive: %s", err)
	}
	defer os.RemoveAll(layerData.Name())

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

	checksum, checksumPayload, err := r.PushImageLayerRegistry(imgData.ID,
		progressreader.New(progressreader.Config{
			In:        layerData,
			Out:       out,
			Formatter: sf,
			Size:      int(layerData.Size),
			NewLines:  false,
			ID:        stringid.TruncateID(imgData.ID),
			Action:    "Pushing",
		}), ep, jsonRaw)
	if err != nil {
		return "", err
	}
	imgData.Checksum = checksum
	imgData.ChecksumPayload = checksumPayload
	// Send the checksum
	if err := r.PushImageChecksumRegistry(imgData, ep); err != nil {
		return "", err
	}

	out.Write(sf.FormatProgress(stringid.TruncateID(imgData.ID), "Image successfully pushed", nil))
	return imgData.Checksum, nil
}

// PushV2Image pushes the image content to the v2 registry, first buffering the contents to disk
func (s *TagStore) pushV2Image(r *registry.Session, img *image.Image, endpoint *registry.Endpoint, imageName string, sf *streamformatter.StreamFormatter, out io.Writer, auth *registry.RequestAuthorization) (string, error) {
	out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Buffering to Disk", nil))

	image, err := s.graph.Get(img.ID)
	if err != nil {
		return "", err
	}
	arch, err := image.TarLayer()
	if err != nil {
		return "", err
	}
	defer arch.Close()

	tf, err := s.graph.newTempFile()
	if err != nil {
		return "", err
	}
	defer func() {
		tf.Close()
		os.Remove(tf.Name())
	}()

	h := sha256.New()
	size, err := bufferToFile(tf, io.TeeReader(arch, h))
	if err != nil {
		return "", err
	}
	dgst := digest.NewDigest("sha256", h)

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

	if err := r.PutV2ImageBlob(endpoint, imageName, dgst.Algorithm(), dgst.Hex(),
		progressreader.New(progressreader.Config{
			In:        tf,
			Out:       out,
			Formatter: sf,
			Size:      int(size),
			NewLines:  false,
			ID:        stringid.TruncateID(img.ID),
			Action:    "Pushing",
		}), auth); err != nil {
		out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Image push failed", nil))
		return "", err
	}
	out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Image successfully pushed", nil))
	return dgst.String(), nil
}

func (s *TagStore) pullV2Tag(r *registry.Session, out io.Writer, endpoint *registry.Endpoint, repoInfo *registry.RepositoryInfo, tag string, sf *streamformatter.StreamFormatter, auth *registry.RequestAuthorization) (bool, error) {
	logrus.Debugf("Pulling tag from V2 registry: %q", tag)

	remoteDigest, manifestBytes, err := r.GetV2ImageManifest(endpoint, repoInfo.RemoteName, tag, auth)
	if err != nil {
		return false, err
	}

	// loadManifest ensures that the manifest payload has the expected digest
	// if the tag is a digest reference.
	localDigest, manifest, verified, err := s.loadManifest(manifestBytes, tag, remoteDigest)
	if err != nil {
		return false, fmt.Errorf("error verifying manifest: %s", err)
	}

	if verified {
		logrus.Printf("Image manifest for %s has been verified", utils.ImageReference(repoInfo.CanonicalName, tag))
	}
	out.Write(sf.FormatStatus(tag, "Pulling from %s", repoInfo.CanonicalName))

	// downloadInfo is used to pass information from download to extractor
	type downloadInfo struct {
		imgJSON    []byte
		img        *image.Image
		digest     digest.Digest
		tmpFile    *os.File
		length     int64
		downloaded bool
		err        chan error
	}

	downloads := make([]downloadInfo, len(manifest.FSLayers))

	for i := len(manifest.FSLayers) - 1; i >= 0; i-- {
		var (
			sumStr  = manifest.FSLayers[i].BlobSum
			imgJSON = []byte(manifest.History[i].V1Compatibility)
		)

		img, err := image.NewImgJSON(imgJSON)
		if err != nil {
			return false, fmt.Errorf("failed to parse json: %s", err)
		}
		downloads[i].img = img

		// Check if exists
		if s.graph.Exists(img.ID) {
			logrus.Debugf("Image already exists: %s", img.ID)
			continue
		}

		dgst, err := digest.ParseDigest(sumStr)
		if err != nil {
			return false, err
		}
		downloads[i].digest = dgst

		out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Pulling fs layer", nil))

		downloadFunc := func(di *downloadInfo) error {
			logrus.Debugf("pulling blob %q to V1 img %s", sumStr, img.ID)

			if c, err := s.poolAdd("pull", "img:"+img.ID); err != nil {
				if c != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Layer already being pulled by another client. Waiting.", nil))
					<-c
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Download complete", nil))
				} else {
					logrus.Debugf("Image (id: %s) pull is already running, skipping: %v", img.ID, err)
				}
			} else {
				defer s.poolRemove("pull", "img:"+img.ID)
				tmpFile, err := ioutil.TempFile("", "GetV2ImageBlob")
				if err != nil {
					return err
				}

				r, l, err := r.GetV2ImageBlobReader(endpoint, repoInfo.RemoteName, di.digest, auth)
				if err != nil {
					return err
				}
				defer r.Close()

				verifier, err := digest.NewDigestVerifier(di.digest)
				if err != nil {
					return err
				}

				if _, err := io.Copy(tmpFile, progressreader.New(progressreader.Config{
					In:        ioutil.NopCloser(io.TeeReader(r, verifier)),
					Out:       out,
					Formatter: sf,
					Size:      int(l),
					NewLines:  false,
					ID:        stringid.TruncateID(img.ID),
					Action:    "Downloading",
				})); err != nil {
					return fmt.Errorf("unable to copy v2 image blob data: %s", err)
				}

//.........这里部分代码省略.........

func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint string, token []string, sf *streamformatter.StreamFormatter) (bool, error) {
	history, err := r.GetRemoteHistory(imgID, endpoint)
	if err != nil {
		return false, err
	}
	out.Write(sf.FormatProgress(stringid.TruncateID(imgID), "Pulling dependent layers", nil))
	// FIXME: Try to stream the images?
	// FIXME: Launch the getRemoteImage() in goroutines

	layersDownloaded := false
	for i := len(history) - 1; i >= 0; i-- {
		id := history[i]

		// ensure no two downloads of the same layer happen at the same time
		if c, err := s.poolAdd("pull", "layer:"+id); err != nil {
			logrus.Debugf("Image (id: %s) pull is already running, skipping: %v", id, err)
			<-c
		}
		defer s.poolRemove("pull", "layer:"+id)

		if !s.graph.Exists(id) {
			out.Write(sf.FormatProgress(stringid.TruncateID(id), "Pulling metadata", nil))
			var (
				imgJSON []byte
				imgSize int
				err     error
				img     *image.Image
			)
			retries := 5
			for j := 1; j <= retries; j++ {
				imgJSON, imgSize, err = r.GetRemoteImageJSON(id, endpoint)
				if err != nil && j == retries {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layersDownloaded, err
				} else if err != nil {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				}
				img, err = image.NewImgJSON(imgJSON)
				layersDownloaded = true
				if err != nil && j == retries {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layersDownloaded, fmt.Errorf("Failed to parse json: %s", err)
				} else if err != nil {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else {
					break
				}
			}

			for j := 1; j <= retries; j++ {
				// Get the layer
				status := "Pulling fs layer"
				if j > 1 {
					status = fmt.Sprintf("Pulling fs layer [retries: %d]", j)
				}
				out.Write(sf.FormatProgress(stringid.TruncateID(id), status, nil))
				layer, err := r.GetRemoteImageLayer(img.ID, endpoint, int64(imgSize))
				if uerr, ok := err.(*url.Error); ok {
					err = uerr.Err
				}
				if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else if err != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error pulling dependent layers", nil))
					return layersDownloaded, err
				}
				layersDownloaded = true
				defer layer.Close()

				err = s.graph.Register(img,
					progressreader.New(progressreader.Config{
						In:        layer,
						Out:       out,
						Formatter: sf,
						Size:      imgSize,
						NewLines:  false,
						ID:        stringid.TruncateID(id),
						Action:    "Downloading",
					}))
				if terr, ok := err.(net.Error); ok && terr.Timeout() && j < retries {
					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
					continue
				} else if err != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(id), "Error downloading dependent layers", nil))
					return layersDownloaded, err
				} else {
					break
				}
			}
		}
		out.Write(sf.FormatProgress(stringid.TruncateID(id), "Download complete", nil))
	}
	return layersDownloaded, nil
}

func (s *TagStore) pullRepository(r *registry.Session, out io.Writer, repoInfo *registry.RepositoryInfo, askedTag string, sf *streamformatter.StreamFormatter) error {
	out.Write(sf.FormatStatus("", "Pulling repository %s", repoInfo.CanonicalName))

	repoData, err := r.GetRepositoryData(repoInfo.RemoteName)
	if err != nil {
		if strings.Contains(err.Error(), "HTTP code: 404") {
			return fmt.Errorf("Error: image %s not found", utils.ImageReference(repoInfo.RemoteName, askedTag))
		}
		// Unexpected HTTP error
		return err
	}

	logrus.Debugf("Retrieving the tag list")
	tagsList, err := r.GetRemoteTags(repoData.Endpoints, repoInfo.RemoteName)
	if err != nil {
		logrus.Errorf("unable to get remote tags: %s", err)
		return err
	}

	for tag, id := range tagsList {
		repoData.ImgList[id] = &registry.ImgData{
			ID:       id,
			Tag:      tag,
			Checksum: "",
		}
	}

	logrus.Debugf("Registering tags")
	// If no tag has been specified, pull them all
	if askedTag == "" {
		for tag, id := range tagsList {
			repoData.ImgList[id].Tag = tag
		}
	} else {
		// Otherwise, check that the tag exists and use only that one
		id, exists := tagsList[askedTag]
		if !exists {
			return fmt.Errorf("Tag %s not found in repository %s", askedTag, repoInfo.CanonicalName)
		}
		repoData.ImgList[id].Tag = askedTag
	}

	errors := make(chan error)

	layersDownloaded := false
	for _, image := range repoData.ImgList {
		downloadImage := func(img *registry.ImgData) {
			if askedTag != "" && img.Tag != askedTag {
				errors <- nil
				return
			}

			if img.Tag == "" {
				logrus.Debugf("Image (id: %s) present in this repository but untagged, skipping", img.ID)
				errors <- nil
				return
			}

			// ensure no two downloads of the same image happen at the same time
			if c, err := s.poolAdd("pull", "img:"+img.ID); err != nil {
				if c != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Layer already being pulled by another client. Waiting.", nil))
					<-c
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Download complete", nil))
				} else {
					logrus.Debugf("Image (id: %s) pull is already running, skipping: %v", img.ID, err)
				}
				errors <- nil
				return
			}
			defer s.poolRemove("pull", "img:"+img.ID)

			out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s", img.Tag, repoInfo.CanonicalName), nil))
			success := false
			var lastErr, err error
			var isDownloaded bool
			for _, ep := range repoInfo.Index.Mirrors {
				// Ensure endpoint is v1
				ep = ep + "v1/"
				out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, mirror: %s", img.Tag, repoInfo.CanonicalName, ep), nil))
				if isDownloaded, err = s.pullImage(r, out, img.ID, ep, repoData.Tokens, sf); err != nil {
					// Don't report errors when pulling from mirrors.
					logrus.Debugf("Error pulling image (%s) from %s, mirror: %s, %s", img.Tag, repoInfo.CanonicalName, ep, err)
					continue
				}
				layersDownloaded = layersDownloaded || isDownloaded
				success = true
				break
			}
			if !success {
				for _, ep := range repoData.Endpoints {
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, endpoint: %s", img.Tag, repoInfo.CanonicalName, ep), nil))
					if isDownloaded, err = s.pullImage(r, out, img.ID, ep, repoData.Tokens, sf); err != nil {
						// It's not ideal that only the last error is returned, it would be better to concatenate the errors.
						// As the error is also given to the output stream the user will see the error.
						lastErr = err
						out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), fmt.Sprintf("Error pulling image (%s) from %s, endpoint: %s, %s", img.Tag, repoInfo.CanonicalName, ep, err), nil))
						continue
					}
					layersDownloaded = layersDownloaded || isDownloaded
//.........这里部分代码省略.........

func (s *TagStore) pushV2Repository(r *registry.Session, localRepo Repository, out io.Writer, repoInfo *registry.RepositoryInfo, tag string, sf *streamformatter.StreamFormatter) error {
	endpoint, err := r.V2RegistryEndpoint(repoInfo.Index)
	if err != nil {
		if repoInfo.Index.Official {
			logrus.Debugf("Unable to push to V2 registry, falling back to v1: %s", err)
			return ErrV2RegistryUnavailable
		}
		return fmt.Errorf("error getting registry endpoint: %s", err)
	}

	tags, err := s.getImageTags(localRepo, tag)
	if err != nil {
		return err
	}
	if len(tags) == 0 {
		return fmt.Errorf("No tags to push for %s", repoInfo.LocalName)
	}

	auth, err := r.GetV2Authorization(endpoint, repoInfo.RemoteName, false)
	if err != nil {
		return fmt.Errorf("error getting authorization: %s", err)
	}

	for _, tag := range tags {
		logrus.Debugf("Pushing repository: %s:%s", repoInfo.CanonicalName, tag)

		layerId, exists := localRepo[tag]
		if !exists {
			return fmt.Errorf("tag does not exist: %s", tag)
		}

		layer, err := s.graph.Get(layerId)
		if err != nil {
			return err
		}

		m := &registry.ManifestData{
			SchemaVersion: 1,
			Name:          repoInfo.RemoteName,
			Tag:           tag,
			Architecture:  layer.Architecture,
		}
		var metadata runconfig.Config
		if layer.Config != nil {
			metadata = *layer.Config
		}

		layersSeen := make(map[string]bool)
		layers := []*image.Image{layer}
		for ; layer != nil; layer, err = s.graph.GetParent(layer) {
			if err != nil {
				return err
			}

			if layersSeen[layer.ID] {
				break
			}
			layers = append(layers, layer)
			layersSeen[layer.ID] = true
		}
		m.FSLayers = make([]*registry.FSLayer, len(layers))
		m.History = make([]*registry.ManifestHistory, len(layers))

		// Schema version 1 requires layer ordering from top to root
		for i, layer := range layers {
			logrus.Debugf("Pushing layer: %s", layer.ID)

			if layer.Config != nil && metadata.Image != layer.ID {
				if err := runconfig.Merge(&metadata, layer.Config); err != nil {
					return err
				}
			}
			jsonData, err := s.graph.RawJSON(layer.ID)
			if err != nil {
				return fmt.Errorf("cannot retrieve the path for %s: %s", layer.ID, err)
			}

			var exists bool
			dgst, err := s.graph.GetDigest(layer.ID)
			if err != nil {
				if err != ErrDigestNotSet {
					return fmt.Errorf("error getting image checksum: %s", err)
				}
			} else {
				// Call mount blob
				exists, err = r.HeadV2ImageBlob(endpoint, repoInfo.RemoteName, dgst, auth)
				if err != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(layer.ID), "Image push failed", nil))
					return err
				}
			}
			if !exists {
				if pushDigest, err := s.pushV2Image(r, layer, endpoint, repoInfo.RemoteName, sf, out, auth); err != nil {
					return err
				} else if pushDigest != dgst {
					// Cache new checksum
					if err := s.graph.SetDigest(layer.ID, pushDigest); err != nil {
						return err
					}
					dgst = pushDigest
//.........这里部分代码省略.........

func (s *TagStore) pullV2Tag(eng *engine.Engine, r *registry.Session, out io.Writer, endpoint *registry.Endpoint, repoInfo *registry.RepositoryInfo, tag string, sf *streamformatter.StreamFormatter, parallel bool, auth *registry.RequestAuthorization) (bool, error) {
	logrus.Debugf("Pulling tag from V2 registry: %q", tag)

	manifestBytes, manifestDigest, err := r.GetV2ImageManifest(endpoint, repoInfo.RemoteName, tag, auth)
	if err != nil {
		return false, err
	}

	// loadManifest ensures that the manifest payload has the expected digest
	// if the tag is a digest reference.
	manifest, verified, err := s.loadManifest(eng, manifestBytes, manifestDigest, tag)
	if err != nil {
		return false, fmt.Errorf("error verifying manifest: %s", err)
	}

	if err := checkValidManifest(manifest); err != nil {
		return false, err
	}

	if verified {
		logrus.Printf("Image manifest for %s has been verified", utils.ImageReference(repoInfo.CanonicalName, tag))
	}
	out.Write(sf.FormatStatus(tag, "Pulling from %s", repoInfo.CanonicalName))

	downloads := make([]downloadInfo, len(manifest.FSLayers))

	for i := len(manifest.FSLayers) - 1; i >= 0; i-- {
		var (
			sumStr  = manifest.FSLayers[i].BlobSum
			imgJSON = []byte(manifest.History[i].V1Compatibility)
		)

		img, err := image.NewImgJSON(imgJSON)
		if err != nil {
			return false, fmt.Errorf("failed to parse json: %s", err)
		}
		downloads[i].img = img

		// Check if exists
		if s.graph.Exists(img.ID) {
			logrus.Debugf("Image already exists: %s", img.ID)
			continue
		}

		dgst, err := digest.ParseDigest(sumStr)
		if err != nil {
			return false, err
		}
		downloads[i].digest = dgst

		out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Pulling fs layer", nil))

		downloadFunc := func(di *downloadInfo) error {
			logrus.Debugf("pulling blob %q to V1 img %s", sumStr, img.ID)

			if c, err := s.poolAdd("pull", "img:"+img.ID); err != nil {
				if c != nil {
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Layer already being pulled by another client. Waiting.", nil))
					<-c
					out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Download complete", nil))
				} else {
					logrus.Debugf("Image (id: %s) pull is already running, skipping: %v", img.ID, err)
				}
			} else {
				defer s.poolRemove("pull", "img:"+img.ID)
				tmpFile, err := ioutil.TempFile("", "GetV2ImageBlob")
				if err != nil {
					return err
				}

				r, l, err := r.GetV2ImageBlobReader(endpoint, repoInfo.RemoteName, di.digest, auth)
				if err != nil {
					return err
				}
				defer r.Close()

				verifier, err := digest.NewDigestVerifier(di.digest)
				if err != nil {
					return err
				}

				if _, err := io.Copy(tmpFile, progressreader.New(progressreader.Config{
					In:        ioutil.NopCloser(io.TeeReader(r, verifier)),
					Out:       out,
					Formatter: sf,
					Size:      int(l),
					NewLines:  false,
					ID:        stringid.TruncateID(img.ID),
					Action:    "Downloading",
				})); err != nil {
					return fmt.Errorf("unable to copy v2 image blob data: %s", err)
				}

				out.Write(sf.FormatProgress(stringid.TruncateID(img.ID), "Verifying Checksum", nil))

				if !verifier.Verified() {
					logrus.Infof("Image verification failed: checksum mismatch for %q", di.digest.String())
					verified = false
				}

//.........这里部分代码省略.........