Enable zstd:chunked support in containers/image

drivers/driver.go

@@ -167,6 +167,40 @@ type Driver interface {
 	LayerIDMapUpdater
 }
 
+// DriverWithDifferOutput is the result of ApplyDiffWithDiffer
+// This API is experimental and can be changed without bumping the major version number.
+type DriverWithDifferOutput struct {
+	Differ             Differ
+	Target             string
+	Size               int64
+	UIDs               []uint32
+	GIDs               []uint32
+	UncompressedDigest digest.Digest
+	Metadata           string
+	BigData            map[string][]byte
+}
+
+// Differ defines the interface for using a custom differ.
+// This API is experimental and can be changed without bumping the major version number.
+type Differ interface {
+	ApplyDiff(dest string, options *archive.TarOptions) (DriverWithDifferOutput, error)
+}
+
+// DriverWithDiffer is the interface for direct diff access.
+// This API is experimental and can be changed without bumping the major version number.
+type DriverWithDiffer interface {
+	Driver
+	// ApplyDiffWithDiffer applies the changes using the callback function.
+	// If id is empty, then a staging directory is created.  The staging directory is guaranteed to be usable with ApplyDiffFromStagingDirectory.
+	ApplyDiffWithDiffer(id, parent string, options *ApplyDiffOpts, differ Differ) (output DriverWithDifferOutput, err error)
+	// ApplyDiffFromStagingDirectory applies the changes using the specified staging directory.
+	ApplyDiffFromStagingDirectory(id, parent, stagingDirectory string, diffOutput *DriverWithDifferOutput, options *ApplyDiffOpts) error
+	// CleanupStagingDirectory cleanups the staging directory.  It can be used to cleanup the staging directory on errors
+	CleanupStagingDirectory(stagingDirectory string) error
+	// DifferTarget gets the location where files are stored for the layer.
+	DifferTarget(id string) (string, error)
+}
+
 // Capabilities defines a list of capabilities a driver may implement.
 // These capabilities are not required; however, they do determine how a
 // graphdriver can be used.

drivers/overlay/overlay.go

@@ -705,6 +705,7 @@ func (d *Driver) Metadata(id string) (map[string]string, error) {
 // is being shutdown. For now, we just have to unmount the bind mounted
 // we had created.
 func (d *Driver) Cleanup() error {
+	_ = os.RemoveAll(d.getStagingDir())
 	return mount.Unmount(d.home)
 }
 
@@ -1490,6 +1491,10 @@ func (f fileGetNilCloser) Close() error {
 	return nil
 }
 
+func (d *Driver) getStagingDir() string {
+	return filepath.Join(d.home, "staging")
+}
+
 // DiffGetter returns a FileGetCloser that can read files from the directory that
 // contains files for the layer differences. Used for direct access for tar-split.
 func (d *Driver) DiffGetter(id string) (graphdriver.FileGetCloser, error) {
@@ -1500,6 +1505,75 @@ func (d *Driver) DiffGetter(id string) (graphdriver.FileGetCloser, error) {
 	return fileGetNilCloser{storage.NewPathFileGetter(p)}, nil
 }
 
+// CleanupStagingDirectory cleanups the staging directory.
+func (d *Driver) CleanupStagingDirectory(stagingDirectory string) error {
+	return os.RemoveAll(stagingDirectory)
+}
+
+// ApplyDiff applies the changes in the new layer using the specified function
+func (d *Driver) ApplyDiffWithDiffer(id, parent string, options *graphdriver.ApplyDiffOpts, differ graphdriver.Differ) (output graphdriver.DriverWithDifferOutput, err error) {
+	var idMappings *idtools.IDMappings
+	if options != nil {
+		idMappings = options.Mappings
+	}
+	if idMappings == nil {
+		idMappings = &idtools.IDMappings{}
+	}
+
+	applyDir := ""
+
+	if id == "" {
+		err := os.MkdirAll(d.getStagingDir(), 0700)
+		if err != nil && !os.IsExist(err) {
+			return graphdriver.DriverWithDifferOutput{}, err
+		}
+		applyDir, err = ioutil.TempDir(d.getStagingDir(), "")
+		if err != nil {
+			return graphdriver.DriverWithDifferOutput{}, err
+		}
+
+	} else {
+		var err error
+		applyDir, err = d.getDiffPath(id)
+		if err != nil {
+			return graphdriver.DriverWithDifferOutput{}, err
+		}
+	}
+
+	logrus.Debugf("Applying differ in %s", applyDir)
+
+	out, err := differ.ApplyDiff(applyDir, &archive.TarOptions{
+		UIDMaps:           idMappings.UIDs(),
+		GIDMaps:           idMappings.GIDs(),
+		IgnoreChownErrors: d.options.ignoreChownErrors,
+		WhiteoutFormat:    d.getWhiteoutFormat(),
+		InUserNS:          rsystem.RunningInUserNS(),
+	})
+	out.Target = applyDir
+	return out, err
+}
+
+// ApplyDiffFromStagingDirectory applies the changes using the specified staging directory.
+func (d *Driver) ApplyDiffFromStagingDirectory(id, parent, stagingDirectory string, diffOutput *graphdriver.DriverWithDifferOutput, options *graphdriver.ApplyDiffOpts) error {
+	if filepath.Dir(stagingDirectory) != d.getStagingDir() {
+		return fmt.Errorf("%q is not a staging directory", stagingDirectory)
+	}
+
+	diff, err := d.getDiffPath(id)
+	if err != nil {
+		return err
+	}
+	if err := os.RemoveAll(diff); err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	return os.Rename(stagingDirectory, diff)
+}
+
+// DifferTarget gets the location where files are stored for the layer.
+func (d *Driver) DifferTarget(id string) (string, error) {
+	return d.getDiffPath(id)
+}
+
 // ApplyDiff applies the new layer into a root
 func (d *Driver) ApplyDiff(id, parent string, options graphdriver.ApplyDiffOpts) (size int64, err error) {
 

errors.go

@@ -53,4 +53,6 @@ var (
 	ErrSizeUnknown = types.ErrSizeUnknown
 	// ErrStoreIsReadOnly is returned when the caller makes a call to a read-only store that would require modifying its contents.
 	ErrStoreIsReadOnly = types.ErrStoreIsReadOnly
+	// ErrNotSupported is returned when the requested functionality is not supported.
+	ErrNotSupported = types.ErrNotSupported
 )

layers.go

@@ -247,6 +247,19 @@ type LayerStore interface {
 	// applies its changes to a specified layer.
 	ApplyDiff(to string, diff io.Reader) (int64, error)
 
+	// ApplyDiffWithDiffer applies the changes through the differ callback function.
+	// If to is the empty string, then a staging directory is created by the driver.
+	ApplyDiffWithDiffer(to string, options *drivers.ApplyDiffOpts, differ drivers.Differ) (*drivers.DriverWithDifferOutput, error)
+
+	// CleanupStagingDirectory cleanups the staging directory.  It can be used to cleanup the staging directory on errors
+	CleanupStagingDirectory(stagingDirectory string) error
+
+	// ApplyDiffFromStagingDirectory uses stagingDirectory to create the diff.
+	ApplyDiffFromStagingDirectory(id, stagingDirectory string, diffOutput *drivers.DriverWithDifferOutput, options *drivers.ApplyDiffOpts) error
+
+	// DifferTarget gets the location where files are stored for the layer.
+	DifferTarget(id string) (string, error)
+
 	// LoadLocked wraps Load in a locked state. This means it loads the store
 	// and cleans-up invalid layers if needed.
 	LoadLocked() error
@@ -1553,6 +1566,93 @@ func (r *layerStore) ApplyDiff(to string, diff io.Reader) (size int64, err error
 	return size, err
 }
 
+func (r *layerStore) DifferTarget(id string) (string, error) {
+	ddriver, ok := r.driver.(drivers.DriverWithDiffer)
+	if !ok {
+		return "", ErrNotSupported
+	}
+	layer, ok := r.lookup(id)
+	if !ok {
+		return "", ErrLayerUnknown
+	}
+	return ddriver.DifferTarget(layer.ID)
+}
+
+func (r *layerStore) ApplyDiffFromStagingDirectory(id, stagingDirectory string, diffOutput *drivers.DriverWithDifferOutput, options *drivers.ApplyDiffOpts) error {
+	ddriver, ok := r.driver.(drivers.DriverWithDiffer)
+	if !ok {
+		return ErrNotSupported
+	}
+	layer, ok := r.lookup(id)
+	if !ok {
+		return ErrLayerUnknown
+	}
+	if options == nil {
+		options = &drivers.ApplyDiffOpts{
+			Mappings:   r.layerMappings(layer),
+			MountLabel: layer.MountLabel,
+		}
+	}
+	err := ddriver.ApplyDiffFromStagingDirectory(layer.ID, layer.Parent, stagingDirectory, diffOutput, options)
+	if err != nil {
+		return err
+	}
+	layer.UIDs = diffOutput.UIDs
+	layer.GIDs = diffOutput.GIDs
+	layer.UncompressedDigest = diffOutput.UncompressedDigest
+	layer.UncompressedSize = diffOutput.Size
+	layer.Metadata = diffOutput.Metadata
+	if err = r.Save(); err != nil {
+		return err
+	}
+	for k, v := range diffOutput.BigData {
+		if err := r.SetBigData(id, k, bytes.NewReader(v)); err != nil {
+			r.Delete(id)
+			return err
+		}
+	}
+	return err
+}
+
+func (r *layerStore) ApplyDiffWithDiffer(to string, options *drivers.ApplyDiffOpts, differ drivers.Differ) (*drivers.DriverWithDifferOutput, error) {
+	ddriver, ok := r.driver.(drivers.DriverWithDiffer)
+	if !ok {
+		return nil, ErrNotSupported
+	}
+
+	if to == "" {
+		output, err := ddriver.ApplyDiffWithDiffer("", "", options, differ)
+		return &output, err
+	}
+
+	layer, ok := r.lookup(to)
+	if !ok {
+		return nil, ErrLayerUnknown
+	}
+	if options == nil {
+		options = &drivers.ApplyDiffOpts{
+			Mappings:   r.layerMappings(layer),
+			MountLabel: layer.MountLabel,
+		}
+	}
+	output, err := ddriver.ApplyDiffWithDiffer(layer.ID, layer.Parent, options, differ)
+	if err != nil {
+		return nil, err
+	}
+	layer.UIDs = output.UIDs
+	layer.GIDs = output.GIDs
+	err = r.Save()
+	return &output, err
+}
+
+func (r *layerStore) CleanupStagingDirectory(stagingDirectory string) error {
+	ddriver, ok := r.driver.(drivers.DriverWithDiffer)
+	if !ok {
+		return ErrNotSupported
+	}
+	return ddriver.CleanupStagingDirectory(stagingDirectory)
+}
+
 func (r *layerStore) layersByDigestMap(m map[digest.Digest][]string, d digest.Digest) ([]Layer, error) {
 	var layers []Layer
 	for _, layerID := range m[d] {