func TestCancelledDownload(t *testing.T) {
	ldm := NewLayerDownloadManager(&mockLayerStore{make(map[layer.ChainID]*mockLayer)}, maxDownloadConcurrency)

	progressChan := make(chan progress.Progress)
	progressDone := make(chan struct{})

	go func() {
		for range progressChan {
		}
		close(progressDone)
	}()

	ctx, cancel := context.WithCancel(context.Background())

	go func() {
		<-time.After(time.Millisecond)
		cancel()
	}()

	descriptors := downloadDescriptors(nil)
	_, _, err := ldm.Download(ctx, *image.NewRootFS(), descriptors, progress.ChanOutput(progressChan))
	if err != context.Canceled {
		t.Fatal("expected download to be cancelled")
	}

	close(progressChan)
	<-progressDone
}

func (mf *v2ManifestFetcher) pullSchema1(ctx context.Context, ref reference.Named, unverifiedManifest *schema1.SignedManifest) (img *image.Image, manifestDigest digest.Digest, err error) {
	var verifiedManifest *schema1.Manifest
	verifiedManifest, err = verifySchema1Manifest(unverifiedManifest, ref)
	if err != nil {
		return nil, "", err
	}

	// remove duplicate layers and check parent chain validity
	err = fixManifestLayers(verifiedManifest)
	if err != nil {
		return nil, "", err
	}

	// Image history converted to the new format
	var history []image.History

	// Note that the order of this loop is in the direction of bottom-most
	// to top-most, so that the downloads slice gets ordered correctly.
	for i := len(verifiedManifest.FSLayers) - 1; i >= 0; i-- {
		var throwAway struct {
			ThrowAway bool `json:"throwaway,omitempty"`
		}
		if err := json.Unmarshal([]byte(verifiedManifest.History[i].V1Compatibility), &throwAway); err != nil {
			return nil, "", err
		}

		h, err := v1.HistoryFromConfig([]byte(verifiedManifest.History[i].V1Compatibility), throwAway.ThrowAway)
		if err != nil {
			return nil, "", err
		}
		history = append(history, h)
	}

	rootFS := image.NewRootFS()
	configRaw, err := makeRawConfigFromV1Config([]byte(verifiedManifest.History[0].V1Compatibility), rootFS, history)

	config, err := json.Marshal(configRaw)
	if err != nil {
		return nil, "", err
	}

	img, err = image.NewFromJSON(config)
	if err != nil {
		return nil, "", err
	}

	manifestDigest = digest.FromBytes(unverifiedManifest.Canonical)

	return img, manifestDigest, nil
}

func (ic *imageCache) restoreCachedImage(parent, target *image.Image, cfg *containertypes.Config) (image.ID, error) {
	var history []image.History
	rootFS := image.NewRootFS()
	lenHistory := 0
	if parent != nil {
		history = parent.History
		rootFS = parent.RootFS
		lenHistory = len(parent.History)
	}
	history = append(history, target.History[lenHistory])
	if layer := getLayerForHistoryIndex(target, lenHistory); layer != "" {
		rootFS.Append(layer)
	}

	config, err := json.Marshal(&image.Image{
		V1Image: image.V1Image{
			DockerVersion: dockerversion.Version,
			Config:        cfg,
			Architecture:  target.Architecture,
			OS:            target.OS,
			Author:        target.Author,
			Created:       history[len(history)-1].Created,
		},
		RootFS:     rootFS,
		History:    history,
		OSFeatures: target.OSFeatures,
		OSVersion:  target.OSVersion,
	})
	if err != nil {
		return "", errors.Wrap(err, "failed to marshal image config")
	}

	imgID, err := ic.daemon.imageStore.Create(config)
	if err != nil {
		return "", errors.Wrap(err, "failed to create cache image")
	}

	if parent != nil {
		if err := ic.daemon.imageStore.SetParent(imgID, parent.ID()); err != nil {
			return "", errors.Wrapf(err, "failed to set parent for %v to %v", target.ID(), parent.ID())
		}
	}
	return imgID, nil
}

func (mf *v1ManifestFetcher) pullImageJSON(imgID, endpoint string, token []string) (*image.Image, error) {
	imgJSON, _, err := mf.session.GetRemoteImageJSON(imgID, endpoint)
	if err != nil {
		return nil, err
	}
	h, err := v1.HistoryFromConfig(imgJSON, false)
	if err != nil {
		return nil, err
	}
	configRaw, err := makeRawConfigFromV1Config(imgJSON, image.NewRootFS(), []image.History{h})
	if err != nil {
		return nil, err
	}
	config, err := json.Marshal(configRaw)
	if err != nil {
		return nil, err
	}
	img, err := image.NewFromJSON(config)
	if err != nil {
		return nil, err
	}
	return img, nil
}

// Commit creates a new filesystem image from the current state of a container.
// The image can optionally be tagged into a repository.
func (daemon *Daemon) Commit(name string, c *ContainerCommitConfig) (string, error) {
	container, err := daemon.Get(name)
	if err != nil {
		return "", err
	}

	// It is not possible to commit a running container on Windows
	if runtime.GOOS == "windows" && container.IsRunning() {
		return "", fmt.Errorf("Windows does not support commit of a running container")
	}

	if c.Pause && !container.isPaused() {
		daemon.containerPause(container)
		defer daemon.containerUnpause(container)
	}

	if c.MergeConfigs {
		if err := runconfig.Merge(c.Config, container.Config); err != nil {
			return "", err
		}
	}

	rwTar, err := daemon.exportContainerRw(container)
	if err != nil {
		return "", err
	}
	defer func() {
		if rwTar != nil {
			rwTar.Close()
		}
	}()

	var history []image.History
	rootFS := image.NewRootFS()

	if container.ImageID != "" {
		img, err := daemon.imageStore.Get(container.ImageID)
		if err != nil {
			return "", err
		}
		history = img.History
		rootFS = img.RootFS
	}

	l, err := daemon.layerStore.Register(rwTar, rootFS.ChainID())
	if err != nil {
		return "", err
	}
	defer layer.ReleaseAndLog(daemon.layerStore, l)

	h := image.History{
		Author:     c.Author,
		Created:    time.Now().UTC(),
		CreatedBy:  strings.Join(container.Config.Cmd.Slice(), " "),
		Comment:    c.Comment,
		EmptyLayer: true,
	}

	if diffID := l.DiffID(); layer.DigestSHA256EmptyTar != diffID {
		h.EmptyLayer = false
		rootFS.Append(diffID)
	}

	history = append(history, h)

	config, err := json.Marshal(&image.Image{
		V1Image: image.V1Image{
			DockerVersion:   dockerversion.Version,
			Config:          c.Config,
			Architecture:    runtime.GOARCH,
			OS:              runtime.GOOS,
			Container:       container.ID,
			ContainerConfig: *container.Config,
			Author:          c.Author,
			Created:         h.Created,
		},
		RootFS:  rootFS,
		History: history,
	})

	if err != nil {
		return "", err
	}

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

	if container.ImageID != "" {
		if err := daemon.imageStore.SetParent(id, container.ImageID); err != nil {
			return "", err
		}
	}

	if c.Repo != "" {
		newTag, err := reference.WithName(c.Repo) // todo: should move this to API layer
		if err != nil {
//.........这里部分代码省略.........

func (p *v2Puller) pullSchema2(ctx context.Context, ref reference.Named, mfst *schema2.DeserializedManifest) (imageID image.ID, manifestDigest digest.Digest, err error) {
	manifestDigest, err = schema2ManifestDigest(ref, mfst)
	if err != nil {
		return "", "", err
	}

	target := mfst.Target()
	imageID = image.ID(target.Digest)
	if _, err := p.config.ImageStore.Get(imageID); err == nil {
		// If the image already exists locally, no need to pull
		// anything.
		return imageID, manifestDigest, nil
	}

	var descriptors []xfer.DownloadDescriptor

	// Note that the order of this loop is in the direction of bottom-most
	// to top-most, so that the downloads slice gets ordered correctly.
	for _, d := range mfst.Layers {
		layerDescriptor := &v2LayerDescriptor{
			digest:            d.Digest,
			repo:              p.repo,
			repoInfo:          p.repoInfo,
			V2MetadataService: p.V2MetadataService,
			src:               d,
		}

		descriptors = append(descriptors, layerDescriptor)
	}

	configChan := make(chan []byte, 1)
	errChan := make(chan error, 1)
	var cancel func()
	ctx, cancel = context.WithCancel(ctx)

	// Pull the image config
	go func() {
		configJSON, err := p.pullSchema2ImageConfig(ctx, target.Digest)
		if err != nil {
			errChan <- ImageConfigPullError{Err: err}
			cancel()
			return
		}
		configChan <- configJSON
	}()

	var (
		configJSON         []byte       // raw serialized image config
		unmarshalledConfig image.Image  // deserialized image config
		downloadRootFS     image.RootFS // rootFS to use for registering layers.
	)

	// https://github.com/docker/docker/issues/24766 - Err on the side of caution,
	// explicitly blocking images intended for linux from the Windows daemon
	if runtime.GOOS == "windows" && unmarshalledConfig.OS == "linux" {
		return "", "", fmt.Errorf("image operating system %q cannot be used on this platform", unmarshalledConfig.OS)
	}

	downloadRootFS = *image.NewRootFS()

	rootFS, release, err := p.config.DownloadManager.Download(ctx, downloadRootFS, descriptors, p.config.ProgressOutput)
	if err != nil {
		if configJSON != nil {
			// Already received the config
			return "", "", err
		}
		select {
		case err = <-errChan:
			return "", "", err
		default:
			cancel()
			select {
			case <-configChan:
			case <-errChan:
			}
			return "", "", err
		}
	}
	defer release()

	if configJSON == nil {
		configJSON, unmarshalledConfig, err = receiveConfig(configChan, errChan)
		if err != nil {
			return "", "", err
		}
	}

	// The DiffIDs returned in rootFS MUST match those in the config.
	// Otherwise the image config could be referencing layers that aren't
	// included in the manifest.
	if len(rootFS.DiffIDs) != len(unmarshalledConfig.RootFS.DiffIDs) {
		return "", "", errRootFSMismatch
	}

	for i := range rootFS.DiffIDs {
		if rootFS.DiffIDs[i] != unmarshalledConfig.RootFS.DiffIDs[i] {
			return "", "", errRootFSMismatch
		}
	}

//.........这里部分代码省略.........

// Commit creates a new filesystem image from the current state of a container.
// The image can optionally be tagged into a repository.
func (daemon *Daemon) Commit(name string, c *backend.ContainerCommitConfig) (string, error) {
	start := time.Now()
	container, err := daemon.GetContainer(name)
	if err != nil {
		return "", err
	}

	// It is not possible to commit a running container on Windows and on Solaris.
	if (runtime.GOOS == "windows" || runtime.GOOS == "solaris") && container.IsRunning() {
		return "", fmt.Errorf("%+v does not support commit of a running container", runtime.GOOS)
	}

	if c.Pause && !container.IsPaused() {
		daemon.containerPause(container)
		defer daemon.containerUnpause(container)
	}

	newConfig, err := dockerfile.BuildFromConfig(c.Config, c.Changes)
	if err != nil {
		return "", err
	}

	if c.MergeConfigs {
		if err := merge(newConfig, container.Config); err != nil {
			return "", err
		}
	}

	rwTar, err := daemon.exportContainerRw(container)
	if err != nil {
		return "", err
	}
	defer func() {
		if rwTar != nil {
			rwTar.Close()
		}
	}()

	var history []image.History
	rootFS := image.NewRootFS()
	osVersion := ""
	var osFeatures []string

	if container.ImageID != "" {
		img, err := daemon.imageStore.Get(container.ImageID)
		if err != nil {
			return "", err
		}
		history = img.History
		rootFS = img.RootFS
		osVersion = img.OSVersion
		osFeatures = img.OSFeatures
	}

	l, err := daemon.layerStore.Register(rwTar, rootFS.ChainID())
	if err != nil {
		return "", err
	}
	defer layer.ReleaseAndLog(daemon.layerStore, l)

	h := image.History{
		Author:     c.Author,
		Created:    time.Now().UTC(),
		CreatedBy:  strings.Join(container.Config.Cmd, " "),
		Comment:    c.Comment,
		EmptyLayer: true,
	}

	if diffID := l.DiffID(); layer.DigestSHA256EmptyTar != diffID {
		h.EmptyLayer = false
		rootFS.Append(diffID)
	}

	history = append(history, h)

	config, err := json.Marshal(&image.Image{
		V1Image: image.V1Image{
			DockerVersion:   dockerversion.Version,
			Config:          newConfig,
			Architecture:    runtime.GOARCH,
			OS:              runtime.GOOS,
			Container:       container.ID,
			ContainerConfig: *container.Config,
			Author:          c.Author,
			Created:         h.Created,
		},
		RootFS:     rootFS,
		History:    history,
		OSFeatures: osFeatures,
		OSVersion:  osVersion,
	})

	if err != nil {
		return "", err
	}

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

// SquashImage creates a new image with the diff of the specified image and the specified parent.
// This new image contains only the layers from it's parent + 1 extra layer which contains the diff of all the layers in between.
// The existing image(s) is not destroyed.
// If no parent is specified, a new image with the diff of all the specified image's layers merged into a new layer that has no parents.
func (daemon *Daemon) SquashImage(id, parent string) (string, error) {
	img, err := daemon.imageStore.Get(image.ID(id))
	if err != nil {
		return "", err
	}

	var parentImg *image.Image
	var parentChainID layer.ChainID
	if len(parent) != 0 {
		parentImg, err = daemon.imageStore.Get(image.ID(parent))
		if err != nil {
			return "", errors.Wrap(err, "error getting specified parent layer")
		}
		parentChainID = parentImg.RootFS.ChainID()
	} else {
		rootFS := image.NewRootFS()
		parentImg = &image.Image{RootFS: rootFS}
	}

	l, err := daemon.layerStore.Get(img.RootFS.ChainID())
	if err != nil {
		return "", errors.Wrap(err, "error getting image layer")
	}
	defer daemon.layerStore.Release(l)

	ts, err := l.TarStreamFrom(parentChainID)
	if err != nil {
		return "", errors.Wrapf(err, "error getting tar stream to parent")
	}
	defer ts.Close()

	newL, err := daemon.layerStore.Register(ts, parentChainID)
	if err != nil {
		return "", errors.Wrap(err, "error registering layer")
	}
	defer daemon.layerStore.Release(newL)

	var newImage image.Image
	newImage = *img
	newImage.RootFS = nil

	var rootFS image.RootFS
	rootFS = *parentImg.RootFS
	rootFS.DiffIDs = append(rootFS.DiffIDs, newL.DiffID())
	newImage.RootFS = &rootFS

	for i, hi := range newImage.History {
		if i >= len(parentImg.History) {
			hi.EmptyLayer = true
		}
		newImage.History[i] = hi
	}

	now := time.Now()
	var historyComment string
	if len(parent) > 0 {
		historyComment = fmt.Sprintf("merge %s to %s", id, parent)
	} else {
		historyComment = fmt.Sprintf("create new from %s", id)
	}

	newImage.History = append(newImage.History, image.History{
		Created: now,
		Comment: historyComment,
	})
	newImage.Created = now

	b, err := json.Marshal(&newImage)
	if err != nil {
		return "", errors.Wrap(err, "error marshalling image config")
	}

	newImgID, err := daemon.imageStore.Create(b)
	if err != nil {
		return "", errors.Wrap(err, "error creating new image after squash")
	}
	return string(newImgID), nil
}

func (p *v2Puller) pullSchema2(ctx context.Context, ref reference.Named, mfst *schema2.DeserializedManifest) (imageID image.ID, manifestDigest digest.Digest, err error) {
	manifestDigest, err = schema2ManifestDigest(ref, mfst)
	if err != nil {
		return "", "", err
	}

	target := mfst.Target()
	imageID = image.ID(target.Digest)
	if _, err := p.config.ImageStore.Get(imageID); err == nil {
		// If the image already exists locally, no need to pull
		// anything.
		return imageID, manifestDigest, nil
	}

	configChan := make(chan []byte, 1)
	errChan := make(chan error, 1)
	var cancel func()
	ctx, cancel = context.WithCancel(ctx)

	// Pull the image config
	go func() {
		configJSON, err := p.pullSchema2ImageConfig(ctx, target.Digest)
		if err != nil {
			errChan <- err
			cancel()
			return
		}
		configChan <- configJSON
	}()

	var descriptors []xfer.DownloadDescriptor

	// Note that the order of this loop is in the direction of bottom-most
	// to top-most, so that the downloads slice gets ordered correctly.
	for _, d := range mfst.References() {
		layerDescriptor := &v2LayerDescriptor{
			digest:         d.Digest,
			repo:           p.repo,
			blobSumService: p.blobSumService,
		}

		descriptors = append(descriptors, layerDescriptor)
	}

	var (
		configJSON         []byte       // raw serialized image config
		unmarshalledConfig image.Image  // deserialized image config
		downloadRootFS     image.RootFS // rootFS to use for registering layers.
	)
	if runtime.GOOS == "windows" {
		configJSON, unmarshalledConfig, err = receiveConfig(configChan, errChan)
		if err != nil {
			return "", "", err
		}
		if unmarshalledConfig.RootFS == nil {
			return "", "", errors.New("image config has no rootfs section")
		}
		downloadRootFS = *unmarshalledConfig.RootFS
		downloadRootFS.DiffIDs = []layer.DiffID{}
	} else {
		downloadRootFS = *image.NewRootFS()
	}

	rootFS, release, err := p.config.DownloadManager.Download(ctx, downloadRootFS, descriptors, p.config.ProgressOutput)
	if err != nil {
		if configJSON != nil {
			// Already received the config
			return "", "", err
		}
		select {
		case err = <-errChan:
			return "", "", err
		default:
			cancel()
			select {
			case <-configChan:
			case <-errChan:
			}
			return "", "", err
		}
	}
	defer release()

	if configJSON == nil {
		configJSON, unmarshalledConfig, err = receiveConfig(configChan, errChan)
		if err != nil {
			return "", "", err
		}
	}

	// The DiffIDs returned in rootFS MUST match those in the config.
	// Otherwise the image config could be referencing layers that aren't
	// included in the manifest.
	if len(rootFS.DiffIDs) != len(unmarshalledConfig.RootFS.DiffIDs) {
		return "", "", errRootFSMismatch
	}

	for i := range rootFS.DiffIDs {
		if rootFS.DiffIDs[i] != unmarshalledConfig.RootFS.DiffIDs[i] {
			return "", "", errRootFSMismatch
//.........这里部分代码省略.........

func (p *v1Puller) pullImage(ctx context.Context, v1ID, endpoint string, localNameRef reference.Named, layersDownloaded *bool) (err error) {
	var history []string
	history, err = p.session.GetRemoteHistory(v1ID, endpoint)
	if err != nil {
		return err
	}
	if len(history) < 1 {
		return fmt.Errorf("empty history for image %s", v1ID)
	}
	progress.Update(p.config.ProgressOutput, stringid.TruncateID(v1ID), "Pulling dependent layers")

	var (
		descriptors []xfer.DownloadDescriptor
		newHistory  []image.History
		imgJSON     []byte
		imgSize     int64
	)

	// Iterate over layers, in order from bottom-most to top-most. Download
	// config for all layers and create descriptors.
	for i := len(history) - 1; i >= 0; i-- {
		v1LayerID := history[i]
		imgJSON, imgSize, err = p.downloadLayerConfig(v1LayerID, endpoint)
		if err != nil {
			return err
		}

		// Create a new-style config from the legacy configs
		h, err := v1.HistoryFromConfig(imgJSON, false)
		if err != nil {
			return err
		}
		newHistory = append(newHistory, h)

		layerDescriptor := &v1LayerDescriptor{
			v1LayerID:        v1LayerID,
			indexName:        p.repoInfo.Index.Name,
			endpoint:         endpoint,
			v1IDService:      p.v1IDService,
			layersDownloaded: layersDownloaded,
			layerSize:        imgSize,
			session:          p.session,
		}

		descriptors = append(descriptors, layerDescriptor)
	}

	rootFS := image.NewRootFS()
	resultRootFS, release, err := p.config.DownloadManager.Download(ctx, *rootFS, descriptors, p.config.ProgressOutput)
	if err != nil {
		return err
	}
	defer release()

	config, err := v1.MakeConfigFromV1Config(imgJSON, &resultRootFS, newHistory)
	if err != nil {
		return err
	}

	imageID, err := p.config.ImageStore.Create(config)
	if err != nil {
		return err
	}

	if err := p.config.ReferenceStore.AddTag(localNameRef, imageID, true); err != nil {
		return err
	}

	return nil
}

// CreateImageConfig constructs the image metadata from layers that compose the image
func CreateImageConfig(images []*ImageWithMeta, manifest *Manifest) error {

	if len(images) == 0 {
		return nil
	}

	imageLayer := images[0] // the layer that represents the actual image
	image := docker.V1Image{}
	rootFS := docker.NewRootFS()
	history := make([]docker.History, 0, len(images))
	diffIDs := make(map[string]string)
	var size int64

	// step through layers to get command history and diffID from oldest to newest
	for i := len(images) - 1; i >= 0; i-- {
		layer := images[i]
		if err := json.Unmarshal([]byte(layer.meta), &image); err != nil {
			return fmt.Errorf("Failed to unmarshall layer history: %s", err)
		}
		h := docker.History{
			Created:   image.Created,
			Author:    image.Author,
			CreatedBy: strings.Join(image.ContainerConfig.Cmd, " "),
			Comment:   image.Comment,
		}
		history = append(history, h)
		rootFS.DiffIDs = append(rootFS.DiffIDs, dockerLayer.DiffID(layer.diffID))
		diffIDs[layer.diffID] = layer.ID
		size += layer.size
	}

	// result is constructed without unused fields
	result := docker.Image{
		V1Image: docker.V1Image{
			Comment:         image.Comment,
			Created:         image.Created,
			Container:       image.Container,
			ContainerConfig: image.ContainerConfig,
			DockerVersion:   image.DockerVersion,
			Author:          image.Author,
			Config:          image.Config,
			Architecture:    image.Architecture,
			OS:              image.OS,
		},
		RootFS:  rootFS,
		History: history,
	}

	bytes, err := result.MarshalJSON()
	if err != nil {
		return fmt.Errorf("Failed to marshall image metadata: %s", err)
	}

	// calculate image ID
	sum := fmt.Sprintf("%x", sha256.Sum256(bytes))
	log.Infof("Image ID: sha256:%s", sum)

	// prepare metadata
	result.V1Image.Parent = image.Parent
	result.Size = size
	result.V1Image.ID = imageLayer.ID
	metaData := metadata.ImageConfig{
		V1Image: result.V1Image,
		ImageID: sum,
		// TODO: this will change when issue 1186 is
		// implemented -- only populate the digests when pulled by digest
		Digests: []string{manifest.Digest},
		Tags:    []string{options.tag},
		Name:    manifest.Name,
		DiffIDs: diffIDs,
		History: history,
	}

	blob, err := json.Marshal(metaData)
	if err != nil {
		return fmt.Errorf("Failed to marshal image metadata: %s", err)
	}

	// store metadata
	imageLayer.meta = string(blob)

	return nil
}

func (p *v1Puller) pullImage(out io.Writer, v1ID, endpoint string, localNameRef reference.Named) (layersDownloaded bool, err error) {
	var history []string
	history, err = p.session.GetRemoteHistory(v1ID, endpoint)
	if err != nil {
		return false, err
	}
	if len(history) < 1 {
		return false, fmt.Errorf("empty history for image %s", v1ID)
	}
	out.Write(p.sf.FormatProgress(stringid.TruncateID(v1ID), "Pulling dependent layers", nil))
	// FIXME: Try to stream the images?
	// FIXME: Launch the getRemoteImage() in goroutines

	var (
		referencedLayers []layer.Layer
		parentID         layer.ChainID
		newHistory       []image.History
		img              *image.V1Image
		imgJSON          []byte
		imgSize          int64
	)

	defer func() {
		for _, l := range referencedLayers {
			layer.ReleaseAndLog(p.config.LayerStore, l)
		}
	}()

	layersDownloaded = false

	// Iterate over layers from top-most to bottom-most, checking if any
	// already exist on disk.
	var i int
	for i = 0; i != len(history); i++ {
		v1LayerID := history[i]
		// Do we have a mapping for this particular v1 ID on this
		// registry?
		if layerID, err := p.v1IDService.Get(v1LayerID, p.repoInfo.Index.Name); err == nil {
			// Does the layer actually exist
			if l, err := p.config.LayerStore.Get(layerID); err == nil {
				for j := i; j >= 0; j-- {
					logrus.Debugf("Layer already exists: %s", history[j])
					out.Write(p.sf.FormatProgress(stringid.TruncateID(history[j]), "Already exists", nil))
				}
				referencedLayers = append(referencedLayers, l)
				parentID = layerID
				break
			}
		}
	}

	needsDownload := i

	// Iterate over layers, in order from bottom-most to top-most. Download
	// config for all layers, and download actual layer data if needed.
	for i = len(history) - 1; i >= 0; i-- {
		v1LayerID := history[i]
		imgJSON, imgSize, err = p.downloadLayerConfig(out, v1LayerID, endpoint)
		if err != nil {
			return layersDownloaded, err
		}

		img = &image.V1Image{}
		if err := json.Unmarshal(imgJSON, img); err != nil {
			return layersDownloaded, err
		}

		if i < needsDownload {
			l, err := p.downloadLayer(out, v1LayerID, endpoint, parentID, imgSize, &layersDownloaded)

			// Note: This needs to be done even in the error case to avoid
			// stale references to the layer.
			if l != nil {
				referencedLayers = append(referencedLayers, l)
			}
			if err != nil {
				return layersDownloaded, err
			}

			parentID = l.ChainID()
		}

		// Create a new-style config from the legacy configs
		h, err := v1.HistoryFromConfig(imgJSON, false)
		if err != nil {
			return layersDownloaded, err
		}
		newHistory = append(newHistory, h)
	}

	rootFS := image.NewRootFS()
	l := referencedLayers[len(referencedLayers)-1]
	for l != nil {
		rootFS.DiffIDs = append([]layer.DiffID{l.DiffID()}, rootFS.DiffIDs...)
		l = l.Parent()
	}

	config, err := v1.MakeConfigFromV1Config(imgJSON, rootFS, newHistory)
	if err != nil {
		return layersDownloaded, err
//.........这里部分代码省略.........

func (p *v2Puller) pullV2Tag(ctx context.Context, ref reference.Named) (tagUpdated bool, err error) {
	tagOrDigest := ""
	if tagged, isTagged := ref.(reference.NamedTagged); isTagged {
		tagOrDigest = tagged.Tag()
	} else if digested, isCanonical := ref.(reference.Canonical); isCanonical {
		tagOrDigest = digested.Digest().String()
	} else {
		return false, fmt.Errorf("internal error: reference has neither a tag nor a digest: %s", ref.String())
	}

	logrus.Debugf("Pulling ref from V2 registry: %q", tagOrDigest)

	manSvc, err := p.repo.Manifests(ctx)
	if err != nil {
		return false, err
	}

	unverifiedManifest, err := manSvc.GetByTag(tagOrDigest)
	if err != nil {
		return false, err
	}
	if unverifiedManifest == nil {
		return false, fmt.Errorf("image manifest does not exist for tag or digest %q", tagOrDigest)
	}

	// If GetByTag succeeded, we can be confident that the registry on
	// the other side speaks the v2 protocol.
	p.confirmedV2 = true

	var verifiedManifest *schema1.Manifest
	verifiedManifest, err = verifyManifest(unverifiedManifest, ref)
	if err != nil {
		return false, err
	}

	rootFS := image.NewRootFS()

	if err := detectBaseLayer(p.config.ImageStore, verifiedManifest, rootFS); err != nil {
		return false, err
	}

	// remove duplicate layers and check parent chain validity
	err = fixManifestLayers(verifiedManifest)
	if err != nil {
		return false, err
	}

	progress.Message(p.config.ProgressOutput, tagOrDigest, "Pulling from "+p.repo.Name())

	var descriptors []xfer.DownloadDescriptor

	// Image history converted to the new format
	var history []image.History

	// Note that the order of this loop is in the direction of bottom-most
	// to top-most, so that the downloads slice gets ordered correctly.
	for i := len(verifiedManifest.FSLayers) - 1; i >= 0; i-- {
		blobSum := verifiedManifest.FSLayers[i].BlobSum

		var throwAway struct {
			ThrowAway bool `json:"throwaway,omitempty"`
		}
		if err := json.Unmarshal([]byte(verifiedManifest.History[i].V1Compatibility), &throwAway); err != nil {
			return false, err
		}

		h, err := v1.HistoryFromConfig([]byte(verifiedManifest.History[i].V1Compatibility), throwAway.ThrowAway)
		if err != nil {
			return false, err
		}
		history = append(history, h)

		if throwAway.ThrowAway {
			continue
		}

		layerDescriptor := &v2LayerDescriptor{
			digest:         blobSum,
			repo:           p.repo,
			blobSumService: p.blobSumService,
		}

		descriptors = append(descriptors, layerDescriptor)
	}

	resultRootFS, release, err := p.config.DownloadManager.Download(ctx, *rootFS, descriptors, p.config.ProgressOutput)
	if err != nil {
		return false, err
	}
	defer release()

	config, err := v1.MakeConfigFromV1Config([]byte(verifiedManifest.History[0].V1Compatibility), &resultRootFS, history)
	if err != nil {
		return false, err
	}

	imageID, err := p.config.ImageStore.Create(config)
	if err != nil {
		return false, err
	}
//.........这里部分代码省略.........

func (p *v2Puller) pullV2Tag(out io.Writer, ref reference.Named) (tagUpdated bool, err error) {
	tagOrDigest := ""
	if tagged, isTagged := ref.(reference.Tagged); isTagged {
		tagOrDigest = tagged.Tag()
	} else if digested, isDigested := ref.(reference.Digested); isDigested {
		tagOrDigest = digested.Digest().String()
	} else {
		return false, fmt.Errorf("internal error: reference has neither a tag nor a digest: %s", ref.String())
	}

	logrus.Debugf("Pulling ref from V2 registry: %q", tagOrDigest)

	manSvc, err := p.repo.Manifests(context.Background())
	if err != nil {
		return false, err
	}

	unverifiedManifest, err := manSvc.GetByTag(tagOrDigest)
	if err != nil {
		return false, err
	}
	if unverifiedManifest == nil {
		return false, fmt.Errorf("image manifest does not exist for tag or digest %q", tagOrDigest)
	}
	var verifiedManifest *schema1.Manifest
	verifiedManifest, err = verifyManifest(unverifiedManifest, ref)
	if err != nil {
		return false, err
	}

	rootFS := image.NewRootFS()

	if err := detectBaseLayer(p.config.ImageStore, verifiedManifest, rootFS); err != nil {
		return false, err
	}

	// remove duplicate layers and check parent chain validity
	err = fixManifestLayers(verifiedManifest)
	if err != nil {
		return false, err
	}

	out.Write(p.sf.FormatStatus(tagOrDigest, "Pulling from %s", p.repo.Name()))

	var downloads []*downloadInfo

	defer func() {
		for _, d := range downloads {
			p.config.Pool.removeWithError(d.poolKey, err)
			if d.tmpFile != nil {
				d.tmpFile.Close()
				if err := os.RemoveAll(d.tmpFile.Name()); err != nil {
					logrus.Errorf("Failed to remove temp file: %s", d.tmpFile.Name())
				}
			}
		}
	}()

	// Image history converted to the new format
	var history []image.History

	poolKey := "v2layer:"
	notFoundLocally := false

	// Note that the order of this loop is in the direction of bottom-most
	// to top-most, so that the downloads slice gets ordered correctly.
	for i := len(verifiedManifest.FSLayers) - 1; i >= 0; i-- {
		blobSum := verifiedManifest.FSLayers[i].BlobSum
		poolKey += blobSum.String()

		var throwAway struct {
			ThrowAway bool `json:"throwaway,omitempty"`
		}
		if err := json.Unmarshal([]byte(verifiedManifest.History[i].V1Compatibility), &throwAway); err != nil {
			return false, err
		}

		h, err := v1.HistoryFromConfig([]byte(verifiedManifest.History[i].V1Compatibility), throwAway.ThrowAway)
		if err != nil {
			return false, err
		}
		history = append(history, h)

		if throwAway.ThrowAway {
			continue
		}

		// Do we have a layer on disk corresponding to the set of
		// blobsums up to this point?
		if !notFoundLocally {
			notFoundLocally = true
			diffID, err := p.blobSumService.GetDiffID(blobSum)
			if err == nil {
				rootFS.Append(diffID)
				if l, err := p.config.LayerStore.Get(rootFS.ChainID()); err == nil {
					notFoundLocally = false
					logrus.Debugf("Layer already exists: %s", blobSum.String())
					out.Write(p.sf.FormatProgress(stringid.TruncateID(blobSum.String()), "Already exists", nil))
					defer layer.ReleaseAndLog(p.config.LayerStore, l)
					continue
//.........这里部分代码省略.........

func (p *v2Puller) pullSchema2(ctx context.Context, ref reference.Named, mfst *schema2.DeserializedManifest) (id digest.Digest, manifestDigest digest.Digest, err error) {
	manifestDigest, err = schema2ManifestDigest(ref, mfst)
	if err != nil {
		return "", "", err
	}

	target := mfst.Target()
	if _, err := p.config.ImageStore.Get(target.Digest); err == nil {
		// If the image already exists locally, no need to pull
		// anything.
		return target.Digest, manifestDigest, nil
	}

	var descriptors []xfer.DownloadDescriptor

	// Note that the order of this loop is in the direction of bottom-most
	// to top-most, so that the downloads slice gets ordered correctly.
	for _, d := range mfst.Layers {
		layerDescriptor := &v2LayerDescriptor{
			digest:            d.Digest,
			repo:              p.repo,
			repoInfo:          p.repoInfo,
			V2MetadataService: p.V2MetadataService,
			src:               d,
		}

		descriptors = append(descriptors, layerDescriptor)
	}

	configChan := make(chan []byte, 1)
	errChan := make(chan error, 1)
	var cancel func()
	ctx, cancel = context.WithCancel(ctx)

	// Pull the image config
	go func() {
		configJSON, err := p.pullSchema2Config(ctx, target.Digest)
		if err != nil {
			errChan <- ImageConfigPullError{Err: err}
			cancel()
			return
		}
		configChan <- configJSON
	}()

	var (
		configJSON       []byte        // raw serialized image config
		downloadedRootFS *image.RootFS // rootFS from registered layers
		configRootFS     *image.RootFS // rootFS from configuration
	)

	// https://github.com/docker/docker/issues/24766 - Err on the side of caution,
	// explicitly blocking images intended for linux from the Windows daemon. On
	// Windows, we do this before the attempt to download, effectively serialising
	// the download slightly slowing it down. We have to do it this way, as
	// chances are the download of layers itself would fail due to file names
	// which aren't suitable for NTFS. At some point in the future, if a similar
	// check to block Windows images being pulled on Linux is implemented, it
	// may be necessary to perform the same type of serialisation.
	if runtime.GOOS == "windows" {
		configJSON, configRootFS, err = receiveConfig(p.config.ImageStore, configChan, errChan)
		if err != nil {
			return "", "", err
		}

		if configRootFS == nil {
			return "", "", errRootFSInvalid
		}
	}

	if p.config.DownloadManager != nil {
		downloadRootFS := *image.NewRootFS()
		rootFS, release, err := p.config.DownloadManager.Download(ctx, downloadRootFS, descriptors, p.config.ProgressOutput)
		if err != nil {
			if configJSON != nil {
				// Already received the config
				return "", "", err
			}
			select {
			case err = <-errChan:
				return "", "", err
			default:
				cancel()
				select {
				case <-configChan:
				case <-errChan:
				}
				return "", "", err
			}
		}
		if release != nil {
			defer release()
		}

		downloadedRootFS = &rootFS
	}

	if configJSON == nil {
		configJSON, configRootFS, err = receiveConfig(p.config.ImageStore, configChan, errChan)
		if err != nil {
//.........这里部分代码省略.........

func (l *tarexporter) legacyLoadImage(oldID, sourceDir string, loadedMap map[string]image.ID, progressOutput progress.Output) error {
	if _, loaded := loadedMap[oldID]; loaded {
		return nil
	}
	configPath, err := safePath(sourceDir, filepath.Join(oldID, legacyConfigFileName))
	if err != nil {
		return err
	}
	imageJSON, err := ioutil.ReadFile(configPath)
	if err != nil {
		logrus.Debugf("Error reading json: %v", err)
		return err
	}

	var img struct{ Parent string }
	if err := json.Unmarshal(imageJSON, &img); err != nil {
		return err
	}

	var parentID image.ID
	if img.Parent != "" {
		for {
			var loaded bool
			if parentID, loaded = loadedMap[img.Parent]; !loaded {
				if err := l.legacyLoadImage(img.Parent, sourceDir, loadedMap, progressOutput); err != nil {
					return err
				}
			} else {
				break
			}
		}
	}

	// todo: try to connect with migrate code
	rootFS := image.NewRootFS()
	var history []image.History

	if parentID != "" {
		parentImg, err := l.is.Get(parentID)
		if err != nil {
			return err
		}

		rootFS = parentImg.RootFS
		history = parentImg.History
	}

	layerPath, err := safePath(sourceDir, filepath.Join(oldID, legacyLayerFileName))
	if err != nil {
		return err
	}
	newLayer, err := l.loadLayer(layerPath, *rootFS, oldID, progressOutput)
	if err != nil {
		return err
	}
	rootFS.Append(newLayer.DiffID())

	h, err := v1.HistoryFromConfig(imageJSON, false)
	if err != nil {
		return err
	}
	history = append(history, h)

	config, err := v1.MakeConfigFromV1Config(imageJSON, rootFS, history)
	if err != nil {
		return err
	}
	imgID, err := l.is.Create(config)
	if err != nil {
		return err
	}

	metadata, err := l.ls.Release(newLayer)
	layer.LogReleaseMetadata(metadata)
	if err != nil {
		return err
	}

	if parentID != "" {
		if err := l.is.SetParent(imgID, parentID); err != nil {
			return err
		}
	}

	loadedMap[oldID] = imgID
	return nil
}

func restoreCustomImage(is image.Store, ls layer.Store, rs reference.Store) error {
	type graphDriverStore interface {
		GraphDriver() graphdriver.Driver
	}

	gds, ok := ls.(graphDriverStore)
	if !ok {
		return nil
	}

	driver := gds.GraphDriver()
	wd, ok := driver.(*windows.Driver)
	if !ok {
		return nil
	}

	imageInfos, err := wd.GetCustomImageInfos()
	if err != nil {
		return err
	}

	// Convert imageData to valid image configuration
	for i := range imageInfos {
		name := strings.ToLower(imageInfos[i].Name)

		type registrar interface {
			RegisterDiffID(graphID string, size int64) (layer.Layer, error)
		}
		r, ok := ls.(registrar)
		if !ok {
			return errors.New("Layerstore doesn't support RegisterDiffID")
		}
		if _, err := r.RegisterDiffID(imageInfos[i].ID, imageInfos[i].Size); err != nil {
			return err
		}
		// layer is intentionally not released

		rootFS := image.NewRootFS()
		rootFS.BaseLayer = filepath.Base(imageInfos[i].Path)

		// Create history for base layer
		config, err := json.Marshal(&image.Image{
			V1Image: image.V1Image{
				DockerVersion: dockerversion.Version,
				Architecture:  runtime.GOARCH,
				OS:            runtime.GOOS,
				Created:       imageInfos[i].CreatedTime,
			},
			RootFS:  rootFS,
			History: []image.History{},
		})

		named, err := reference.ParseNamed(name)
		if err != nil {
			return err
		}

		ref, err := reference.WithTag(named, imageInfos[i].Version)
		if err != nil {
			return err
		}

		id, err := is.Create(config)
		if err != nil {
			return err
		}

		if err := rs.AddTag(ref, id, true); err != nil {
			return err
		}

		logrus.Debugf("Registered base layer %s as %s", ref, id)
	}
	return nil
}

func migrateImage(id, root string, ls graphIDRegistrar, is image.Store, ms metadata.Store, mappings map[string]image.ID) (err error) {
	defer func() {
		if err != nil {
			logrus.Errorf("migration failed for %v, err: %v", id, err)
		}
	}()

	jsonFile := filepath.Join(root, graphDirName, id, "json")
	imageJSON, err := ioutil.ReadFile(jsonFile)
	if err != nil {
		return err
	}
	var parent struct {
		Parent   string
		ParentID digest.Digest `json:"parent_id"`
	}
	if err := json.Unmarshal(imageJSON, &parent); err != nil {
		return err
	}
	if parent.Parent == &q