Update vendor

vendor/github.com/google/go-containerregistry/pkg/v1/partial/README.md

@@ -0,0 +1,66 @@
+# `partial`
+
+[![GoDoc](https://godoc.org/github.com/google/go-containerregistry/pkg/v1/partial?status.svg)](https://godoc.org/github.com/google/go-containerregistry/pkg/v1/partial)
+
+## Partial Implementations
+
+There are roughly two kinds of image representations: compressed and uncompressed.
+
+The implementations for these kinds of images are almost identical, with the only
+major difference being how blobs (config and layers) are fetched. This common
+code lives in this package, where you provide a _partial_ implementation of a
+compressed or uncompressed image, and you get back a full `v1.Image` implementation.
+
+### Examples
+
+In a registry, blobs are compressed, so it's easiest to implement a `v1.Image` in terms
+of compressed layers. `remote.remoteImage` does this by implementing `CompressedImageCore`:
+
+```go
+type CompressedImageCore interface {
+	RawConfigFile() ([]byte, error)
+	MediaType() (types.MediaType, error)
+	RawManifest() ([]byte, error)
+	LayerByDigest(v1.Hash) (CompressedLayer, error)
+}
+```
+
+In a tarball, blobs are (often) uncompressed, so it's easiest to implement a `v1.Image` in terms
+of uncompressed layers. `tarball.uncompressedImage` does this by implementing `UncompressedImageCore`:
+
+```go
+type CompressedImageCore interface {
+	RawConfigFile() ([]byte, error)
+	MediaType() (types.MediaType, error)
+	LayerByDiffID(v1.Hash) (UncompressedLayer, error)
+}
+```
+
+## Optional Methods
+
+Where possible, we access some information via optional methods as an optimization.
+
+### [`partial.Descriptor`](https://godoc.org/github.com/google/go-containerregistry/pkg/v1/partial#Descriptor)
+
+There are some properties of a [`Descriptor`](https://github.com/opencontainers/image-spec/blob/master/descriptor.md#properties) that aren't derivable from just image data:
+
+* `MediaType`
+* `Platform`
+* `URLs`
+* `Annotations`
+
+For example, in a `tarball.Image`, there is a `LayerSources` field that contains
+an entire layer descriptor with `URLs` information for foreign layers. This
+information can be passed through to callers by implementing this optional
+`Descriptor` method.
+
+See [`#654`](https://github.com/google/go-containerregistry/pull/654).
+
+### [`partial.UncompressedSize`](https://godoc.org/github.com/google/go-containerregistry/pkg/v1/partial#UncompressedSize)
+
+Usually, you don't need to know the uncompressed size of a layer, since that
+information isn't stored in a config file (just he sha256 is needed); however,
+there are cases where it is very helpful to know the layer size, e.g. when
+writing the uncompressed layer into a tarball.
+
+See [`#655`](https://github.com/google/go-containerregistry/pull/655).

vendor/github.com/google/go-containerregistry/pkg/v1/partial/compressed.go

@@ -0,0 +1,163 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package partial
+
+import (
+	"io"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+	"github.com/google/go-containerregistry/pkg/v1/v1util"
+)
+
+// CompressedLayer represents the bare minimum interface a natively
+// compressed layer must implement for us to produce a v1.Layer
+type CompressedLayer interface {
+	// Digest returns the Hash of the compressed layer.
+	Digest() (v1.Hash, error)
+
+	// Compressed returns an io.ReadCloser for the compressed layer contents.
+	Compressed() (io.ReadCloser, error)
+
+	// Size returns the compressed size of the Layer.
+	Size() (int64, error)
+
+	// Returns the mediaType for the compressed Layer
+	MediaType() (types.MediaType, error)
+}
+
+// compressedLayerExtender implements v1.Image using the compressed base properties.
+type compressedLayerExtender struct {
+	CompressedLayer
+}
+
+// Uncompressed implements v1.Layer
+func (cle *compressedLayerExtender) Uncompressed() (io.ReadCloser, error) {
+	r, err := cle.Compressed()
+	if err != nil {
+		return nil, err
+	}
+	return v1util.GunzipReadCloser(r)
+}
+
+// DiffID implements v1.Layer
+func (cle *compressedLayerExtender) DiffID() (v1.Hash, error) {
+	// If our nested CompressedLayer implements DiffID,
+	// then delegate to it instead.
+	if wdi, ok := cle.CompressedLayer.(WithDiffID); ok {
+		return wdi.DiffID()
+	}
+	r, err := cle.Uncompressed()
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	defer r.Close()
+	h, _, err := v1.SHA256(r)
+	return h, err
+}
+
+// CompressedToLayer fills in the missing methods from a CompressedLayer so that it implements v1.Layer
+func CompressedToLayer(ul CompressedLayer) (v1.Layer, error) {
+	return &compressedLayerExtender{ul}, nil
+}
+
+// CompressedImageCore represents the base minimum interface a natively
+// compressed image must implement for us to produce a v1.Image.
+type CompressedImageCore interface {
+	ImageCore
+
+	// RawManifest returns the serialized bytes of the manifest.
+	RawManifest() ([]byte, error)
+
+	// LayerByDigest is a variation on the v1.Image method, which returns
+	// a CompressedLayer instead.
+	LayerByDigest(v1.Hash) (CompressedLayer, error)
+}
+
+// compressedImageExtender implements v1.Image by extending CompressedImageCore with the
+// appropriate methods computed from the minimal core.
+type compressedImageExtender struct {
+	CompressedImageCore
+}
+
+// Assert that our extender type completes the v1.Image interface
+var _ v1.Image = (*compressedImageExtender)(nil)
+
+// Digest implements v1.Image
+func (i *compressedImageExtender) Digest() (v1.Hash, error) {
+	return Digest(i)
+}
+
+// ConfigName implements v1.Image
+func (i *compressedImageExtender) ConfigName() (v1.Hash, error) {
+	return ConfigName(i)
+}
+
+// Layers implements v1.Image
+func (i *compressedImageExtender) Layers() ([]v1.Layer, error) {
+	hs, err := FSLayers(i)
+	if err != nil {
+		return nil, err
+	}
+	ls := make([]v1.Layer, 0, len(hs))
+	for _, h := range hs {
+		l, err := i.LayerByDigest(h)
+		if err != nil {
+			return nil, err
+		}
+		ls = append(ls, l)
+	}
+	return ls, nil
+}
+
+// LayerByDigest implements v1.Image
+func (i *compressedImageExtender) LayerByDigest(h v1.Hash) (v1.Layer, error) {
+	cl, err := i.CompressedImageCore.LayerByDigest(h)
+	if err != nil {
+		return nil, err
+	}
+	return CompressedToLayer(cl)
+}
+
+// LayerByDiffID implements v1.Image
+func (i *compressedImageExtender) LayerByDiffID(h v1.Hash) (v1.Layer, error) {
+	h, err := DiffIDToBlob(i, h)
+	if err != nil {
+		return nil, err
+	}
+	return i.LayerByDigest(h)
+}
+
+// ConfigFile implements v1.Image
+func (i *compressedImageExtender) ConfigFile() (*v1.ConfigFile, error) {
+	return ConfigFile(i)
+}
+
+// Manifest implements v1.Image
+func (i *compressedImageExtender) Manifest() (*v1.Manifest, error) {
+	return Manifest(i)
+}
+
+// Size implements v1.Image
+func (i *compressedImageExtender) Size() (int64, error) {
+	return Size(i)
+}
+
+// CompressedToImage fills in the missing methods from a CompressedImageCore so that it implements v1.Image
+func CompressedToImage(cic CompressedImageCore) (v1.Image, error) {
+	return &compressedImageExtender{
+		CompressedImageCore: cic,
+	}, nil
+}

vendor/github.com/google/go-containerregistry/pkg/v1/partial/doc.go

@@ -0,0 +1,17 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package partial defines methods for building up a v1.Image from
+// minimal subsets that are sufficient for defining a v1.Image.
+package partial

vendor/github.com/google/go-containerregistry/pkg/v1/partial/image.go

@@ -0,0 +1,28 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package partial
+
+import (
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+// ImageCore is the core set of properties without which we cannot build a v1.Image
+type ImageCore interface {
+	// RawConfigFile returns the serialized bytes of this image's config file.
+	RawConfigFile() ([]byte, error)
+
+	// MediaType of this image's manifest.
+	MediaType() (types.MediaType, error)
+}

vendor/github.com/google/go-containerregistry/pkg/v1/partial/index.go

@@ -0,0 +1,85 @@
+// Copyright 2020 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package partial
+
+import (
+	"fmt"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/match"
+)
+
+// FindManifests given a v1.ImageIndex, find the manifests that fit the matcher.
+func FindManifests(index v1.ImageIndex, matcher match.Matcher) ([]v1.Descriptor, error) {
+	// get the actual manifest list
+	indexManifest, err := index.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("unable to get raw index: %v", err)
+	}
+	manifests := []v1.Descriptor{}
+	// try to get the root of our image
+	for _, manifest := range indexManifest.Manifests {
+		if matcher(manifest) {
+			manifests = append(manifests, manifest)
+		}
+	}
+	return manifests, nil
+}
+
+// FindImages given a v1.ImageIndex, find the images that fit the matcher. If a Descriptor
+// matches the provider Matcher, but the referenced item is not an Image, ignores it.
+// Only returns those that match the Matcher and are images.
+func FindImages(index v1.ImageIndex, matcher match.Matcher) ([]v1.Image, error) {
+	matches := []v1.Image{}
+	manifests, err := FindManifests(index, matcher)
+	if err != nil {
+		return nil, err
+	}
+	for _, desc := range manifests {
+		// if it is not an image, ignore it
+		if !desc.MediaType.IsImage() {
+			continue
+		}
+		img, err := index.Image(desc.Digest)
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, img)
+	}
+	return matches, nil
+}
+
+// FindIndexes given a v1.ImageIndex, find the indexes that fit the matcher. If a Descriptor
+// matches the provider Matcher, but the referenced item is not an Index, ignores it.
+// Only returns those that match the Matcher and are indexes.
+func FindIndexes(index v1.ImageIndex, matcher match.Matcher) ([]v1.ImageIndex, error) {
+	matches := []v1.ImageIndex{}
+	manifests, err := FindManifests(index, matcher)
+	if err != nil {
+		return nil, err
+	}
+	for _, desc := range manifests {
+		if !desc.MediaType.IsIndex() {
+			continue
+		}
+		// if it is not an index, ignore it
+		idx, err := index.ImageIndex(desc.Digest)
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, idx)
+	}
+	return matches, nil
+}

vendor/github.com/google/go-containerregistry/pkg/v1/partial/uncompressed.go

@@ -0,0 +1,223 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package partial
+
+import (
+	"bytes"
+	"io"
+	"sync"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+	"github.com/google/go-containerregistry/pkg/v1/v1util"
+)
+
+// UncompressedLayer represents the bare minimum interface a natively
+// uncompressed layer must implement for us to produce a v1.Layer
+type UncompressedLayer interface {
+	// DiffID returns the Hash of the uncompressed layer.
+	DiffID() (v1.Hash, error)
+
+	// Uncompressed returns an io.ReadCloser for the uncompressed layer contents.
+	Uncompressed() (io.ReadCloser, error)
+
+	// Returns the mediaType for the compressed Layer
+	MediaType() (types.MediaType, error)
+}
+
+// uncompressedLayerExtender implements v1.Image using the uncompressed base properties.
+type uncompressedLayerExtender struct {
+	UncompressedLayer
+	// Memoize size/hash so that the methods aren't twice as
+	// expensive as doing this manually.
+	hash          v1.Hash
+	size          int64
+	hashSizeError error
+	once          sync.Once
+}
+
+// Compressed implements v1.Layer
+func (ule *uncompressedLayerExtender) Compressed() (io.ReadCloser, error) {
+	u, err := ule.Uncompressed()
+	if err != nil {
+		return nil, err
+	}
+	return v1util.GzipReadCloser(u), nil
+}
+
+// Digest implements v1.Layer
+func (ule *uncompressedLayerExtender) Digest() (v1.Hash, error) {
+	ule.calcSizeHash()
+	return ule.hash, ule.hashSizeError
+}
+
+// Size implements v1.Layer
+func (ule *uncompressedLayerExtender) Size() (int64, error) {
+	ule.calcSizeHash()
+	return ule.size, ule.hashSizeError
+}
+
+func (ule *uncompressedLayerExtender) calcSizeHash() {
+	ule.once.Do(func() {
+		var r io.ReadCloser
+		r, ule.hashSizeError = ule.Compressed()
+		if ule.hashSizeError != nil {
+			return
+		}
+		defer r.Close()
+		ule.hash, ule.size, ule.hashSizeError = v1.SHA256(r)
+	})
+}
+
+// UncompressedToLayer fills in the missing methods from an UncompressedLayer so that it implements v1.Layer
+func UncompressedToLayer(ul UncompressedLayer) (v1.Layer, error) {
+	return &uncompressedLayerExtender{UncompressedLayer: ul}, nil
+}
+
+// UncompressedImageCore represents the bare minimum interface a natively
+// uncompressed image must implement for us to produce a v1.Image
+type UncompressedImageCore interface {
+	ImageCore
+
+	// LayerByDiffID is a variation on the v1.Image method, which returns
+	// an UncompressedLayer instead.
+	LayerByDiffID(v1.Hash) (UncompressedLayer, error)
+}
+
+// UncompressedToImage fills in the missing methods from an UncompressedImageCore so that it implements v1.Image.
+func UncompressedToImage(uic UncompressedImageCore) (v1.Image, error) {
+	return &uncompressedImageExtender{
+		UncompressedImageCore: uic,
+	}, nil
+}
+
+// uncompressedImageExtender implements v1.Image by extending UncompressedImageCore with the
+// appropriate methods computed from the minimal core.
+type uncompressedImageExtender struct {
+	UncompressedImageCore
+
+	lock     sync.Mutex
+	manifest *v1.Manifest
+}
+
+// Assert that our extender type completes the v1.Image interface
+var _ v1.Image = (*uncompressedImageExtender)(nil)
+
+// Digest implements v1.Image
+func (i *uncompressedImageExtender) Digest() (v1.Hash, error) {
+	return Digest(i)
+}
+
+// Manifest implements v1.Image
+func (i *uncompressedImageExtender) Manifest() (*v1.Manifest, error) {
+	i.lock.Lock()
+	defer i.lock.Unlock()
+	if i.manifest != nil {
+		return i.manifest, nil
+	}
+
+	b, err := i.RawConfigFile()
+	if err != nil {
+		return nil, err
+	}
+
+	cfgHash, cfgSize, err := v1.SHA256(bytes.NewReader(b))
+	if err != nil {
+		return nil, err
+	}
+
+	m := &v1.Manifest{
+		SchemaVersion: 2,
+		MediaType:     types.DockerManifestSchema2,
+		Config: v1.Descriptor{
+			MediaType: types.DockerConfigJSON,
+			Size:      cfgSize,
+			Digest:    cfgHash,
+		},
+	}
+
+	ls, err := i.Layers()
+	if err != nil {
+		return nil, err
+	}
+
+	m.Layers = make([]v1.Descriptor, len(ls))
+	for i, l := range ls {
+		desc, err := Descriptor(l)
+		if err != nil {
+			return nil, err
+		}
+
+		m.Layers[i] = *desc
+	}
+
+	i.manifest = m
+	return i.manifest, nil
+}
+
+// RawManifest implements v1.Image
+func (i *uncompressedImageExtender) RawManifest() ([]byte, error) {
+	return RawManifest(i)
+}
+
+// Size implements v1.Image
+func (i *uncompressedImageExtender) Size() (int64, error) {
+	return Size(i)
+}
+
+// ConfigName implements v1.Image
+func (i *uncompressedImageExtender) ConfigName() (v1.Hash, error) {
+	return ConfigName(i)
+}
+
+// ConfigFile implements v1.Image
+func (i *uncompressedImageExtender) ConfigFile() (*v1.ConfigFile, error) {
+	return ConfigFile(i)
+}
+
+// Layers implements v1.Image
+func (i *uncompressedImageExtender) Layers() ([]v1.Layer, error) {
+	diffIDs, err := DiffIDs(i)
+	if err != nil {
+		return nil, err
+	}
+	ls := make([]v1.Layer, 0, len(diffIDs))
+	for _, h := range diffIDs {
+		l, err := i.LayerByDiffID(h)
+		if err != nil {
+			return nil, err
+		}
+		ls = append(ls, l)
+	}
+	return ls, nil
+}
+
+// LayerByDiffID implements v1.Image
+func (i *uncompressedImageExtender) LayerByDiffID(diffID v1.Hash) (v1.Layer, error) {
+	ul, err := i.UncompressedImageCore.LayerByDiffID(diffID)
+	if err != nil {
+		return nil, err
+	}
+	return UncompressedToLayer(ul)
+}
+
+// LayerByDigest implements v1.Image
+func (i *uncompressedImageExtender) LayerByDigest(h v1.Hash) (v1.Layer, error) {
+	diffID, err := BlobToDiffID(i, h)
+	if err != nil {
+		return nil, err
+	}
+	return i.LayerByDiffID(diffID)
+}

vendor/github.com/google/go-containerregistry/pkg/v1/partial/with.go

@@ -0,0 +1,382 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package partial
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+// WithRawConfigFile defines the subset of v1.Image used by these helper methods
+type WithRawConfigFile interface {
+	// RawConfigFile returns the serialized bytes of this image's config file.
+	RawConfigFile() ([]byte, error)
+}
+
+// ConfigFile is a helper for implementing v1.Image
+func ConfigFile(i WithRawConfigFile) (*v1.ConfigFile, error) {
+	b, err := i.RawConfigFile()
+	if err != nil {
+		return nil, err
+	}
+	return v1.ParseConfigFile(bytes.NewReader(b))
+}
+
+// ConfigName is a helper for implementing v1.Image
+func ConfigName(i WithRawConfigFile) (v1.Hash, error) {
+	b, err := i.RawConfigFile()
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	h, _, err := v1.SHA256(bytes.NewReader(b))
+	return h, err
+}
+
+type configLayer struct {
+	hash    v1.Hash
+	content []byte
+}
+
+// Digest implements v1.Layer
+func (cl *configLayer) Digest() (v1.Hash, error) {
+	return cl.hash, nil
+}
+
+// DiffID implements v1.Layer
+func (cl *configLayer) DiffID() (v1.Hash, error) {
+	return cl.hash, nil
+}
+
+// Uncompressed implements v1.Layer
+func (cl *configLayer) Uncompressed() (io.ReadCloser, error) {
+	return ioutil.NopCloser(bytes.NewBuffer(cl.content)), nil
+}
+
+// Compressed implements v1.Layer
+func (cl *configLayer) Compressed() (io.ReadCloser, error) {
+	return ioutil.NopCloser(bytes.NewBuffer(cl.content)), nil
+}
+
+// Size implements v1.Layer
+func (cl *configLayer) Size() (int64, error) {
+	return int64(len(cl.content)), nil
+}
+
+func (cl *configLayer) MediaType() (types.MediaType, error) {
+	// Defaulting this to OCIConfigJSON as it should remain
+	// backwards compatible with DockerConfigJSON
+	return types.OCIConfigJSON, nil
+}
+
+var _ v1.Layer = (*configLayer)(nil)
+
+// ConfigLayer implements v1.Layer from the raw config bytes.
+// This is so that clients (e.g. remote) can access the config as a blob.
+func ConfigLayer(i WithRawConfigFile) (v1.Layer, error) {
+	h, err := ConfigName(i)
+	if err != nil {
+		return nil, err
+	}
+	rcfg, err := i.RawConfigFile()
+	if err != nil {
+		return nil, err
+	}
+	return &configLayer{
+		hash:    h,
+		content: rcfg,
+	}, nil
+}
+
+// WithConfigFile defines the subset of v1.Image used by these helper methods
+type WithConfigFile interface {
+	// ConfigFile returns this image's config file.
+	ConfigFile() (*v1.ConfigFile, error)
+}
+
+// DiffIDs is a helper for implementing v1.Image
+func DiffIDs(i WithConfigFile) ([]v1.Hash, error) {
+	cfg, err := i.ConfigFile()
+	if err != nil {
+		return nil, err
+	}
+	return cfg.RootFS.DiffIDs, nil
+}
+
+// RawConfigFile is a helper for implementing v1.Image
+func RawConfigFile(i WithConfigFile) ([]byte, error) {
+	cfg, err := i.ConfigFile()
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(cfg)
+}
+
+// WithRawManifest defines the subset of v1.Image used by these helper methods
+type WithRawManifest interface {
+	// RawManifest returns the serialized bytes of this image's config file.
+	RawManifest() ([]byte, error)
+}
+
+// Digest is a helper for implementing v1.Image
+func Digest(i WithRawManifest) (v1.Hash, error) {
+	mb, err := i.RawManifest()
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	digest, _, err := v1.SHA256(bytes.NewReader(mb))
+	return digest, err
+}
+
+// Manifest is a helper for implementing v1.Image
+func Manifest(i WithRawManifest) (*v1.Manifest, error) {
+	b, err := i.RawManifest()
+	if err != nil {
+		return nil, err
+	}
+	return v1.ParseManifest(bytes.NewReader(b))
+}
+
+// WithManifest defines the subset of v1.Image used by these helper methods
+type WithManifest interface {
+	// Manifest returns this image's Manifest object.
+	Manifest() (*v1.Manifest, error)
+}
+
+// RawManifest is a helper for implementing v1.Image
+func RawManifest(i WithManifest) ([]byte, error) {
+	m, err := i.Manifest()
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(m)
+}
+
+// Size is a helper for implementing v1.Image
+func Size(i WithRawManifest) (int64, error) {
+	b, err := i.RawManifest()
+	if err != nil {
+		return -1, err
+	}
+	return int64(len(b)), nil
+}
+
+// FSLayers is a helper for implementing v1.Image
+func FSLayers(i WithManifest) ([]v1.Hash, error) {
+	m, err := i.Manifest()
+	if err != nil {
+		return nil, err
+	}
+	fsl := make([]v1.Hash, len(m.Layers))
+	for i, l := range m.Layers {
+		fsl[i] = l.Digest
+	}
+	return fsl, nil
+}
+
+// BlobSize is a helper for implementing v1.Image
+func BlobSize(i WithManifest, h v1.Hash) (int64, error) {
+	d, err := BlobDescriptor(i, h)
+	if err != nil {
+		return -1, err
+	}
+	return d.Size, nil
+}
+
+// BlobDescriptor is a helper for implementing v1.Image
+func BlobDescriptor(i WithManifest, h v1.Hash) (*v1.Descriptor, error) {
+	m, err := i.Manifest()
+	if err != nil {
+		return nil, err
+	}
+
+	if m.Config.Digest == h {
+		return &m.Config, nil
+	}
+
+	for _, l := range m.Layers {
+		if l.Digest == h {
+			return &l, nil
+		}
+	}
+	return nil, fmt.Errorf("blob %v not found", h)
+}
+
+// WithManifestAndConfigFile defines the subset of v1.Image used by these helper methods
+type WithManifestAndConfigFile interface {
+	WithConfigFile
+
+	// Manifest returns this image's Manifest object.
+	Manifest() (*v1.Manifest, error)
+}
+
+// BlobToDiffID is a helper for mapping between compressed
+// and uncompressed blob hashes.
+func BlobToDiffID(i WithManifestAndConfigFile, h v1.Hash) (v1.Hash, error) {
+	blobs, err := FSLayers(i)
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	diffIDs, err := DiffIDs(i)
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	if len(blobs) != len(diffIDs) {
+		return v1.Hash{}, fmt.Errorf("mismatched fs layers (%d) and diff ids (%d)", len(blobs), len(diffIDs))
+	}
+	for i, blob := range blobs {
+		if blob == h {
+			return diffIDs[i], nil
+		}
+	}
+	return v1.Hash{}, fmt.Errorf("unknown blob %v", h)
+}
+
+// DiffIDToBlob is a helper for mapping between uncompressed
+// and compressed blob hashes.
+func DiffIDToBlob(wm WithManifestAndConfigFile, h v1.Hash) (v1.Hash, error) {
+	blobs, err := FSLayers(wm)
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	diffIDs, err := DiffIDs(wm)
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	if len(blobs) != len(diffIDs) {
+		return v1.Hash{}, fmt.Errorf("mismatched fs layers (%d) and diff ids (%d)", len(blobs), len(diffIDs))
+	}
+	for i, diffID := range diffIDs {
+		if diffID == h {
+			return blobs[i], nil
+		}
+	}
+	return v1.Hash{}, fmt.Errorf("unknown diffID %v", h)
+}
+
+// WithDiffID defines the subset of v1.Layer for exposing the DiffID method.
+type WithDiffID interface {
+	DiffID() (v1.Hash, error)
+}
+
+// withDescriptor allows partial layer implementations to provide a layer
+// descriptor to the partial image manifest builder. This allows partial
+// uncompressed layers to provide foreign layer metadata like URLs to the
+// uncompressed image manifest.
+type withDescriptor interface {
+	Descriptor() (*v1.Descriptor, error)
+}
+
+// Describable represents something for which we can produce a v1.Descriptor.
+type Describable interface {
+	Digest() (v1.Hash, error)
+	MediaType() (types.MediaType, error)
+	Size() (int64, error)
+}
+
+// Descriptor returns a v1.Descriptor given a Describable. It also encodes
+// some logic for unwrapping things that have been wrapped by
+// CompressedToLayer, UncompressedToLayer, CompressedToImage, or
+// UncompressedToImage.
+func Descriptor(d Describable) (*v1.Descriptor, error) {
+	// If Describable implements Descriptor itself, return that.
+	if wd, ok := d.(withDescriptor); ok {
+		return wd.Descriptor()
+	}
+
+	// Otherwise, try to unwrap any partial implementations to see
+	// if the wrapped struct implements Descriptor.
+	if ule, ok := d.(*uncompressedLayerExtender); ok {
+		if wd, ok := ule.UncompressedLayer.(withDescriptor); ok {
+			return wd.Descriptor()
+		}
+	}
+	if cle, ok := d.(*compressedLayerExtender); ok {
+		if wd, ok := cle.CompressedLayer.(withDescriptor); ok {
+			return wd.Descriptor()
+		}
+	}
+	if uie, ok := d.(*uncompressedImageExtender); ok {
+		if wd, ok := uie.UncompressedImageCore.(withDescriptor); ok {
+			return wd.Descriptor()
+		}
+	}
+	if cie, ok := d.(*compressedImageExtender); ok {
+		if wd, ok := cie.CompressedImageCore.(withDescriptor); ok {
+			return wd.Descriptor()
+		}
+	}
+
+	// If all else fails, compute the descriptor from the individual methods.
+	var (
+		desc v1.Descriptor
+		err  error
+	)
+
+	if desc.Size, err = d.Size(); err != nil {
+		return nil, err
+	}
+	if desc.Digest, err = d.Digest(); err != nil {
+		return nil, err
+	}
+	if desc.MediaType, err = d.MediaType(); err != nil {
+		return nil, err
+	}
+
+	return &desc, nil
+}
+
+type withUncompressedSize interface {
+	UncompressedSize() (int64, error)
+}
+
+// UncompressedSize returns the size of the Uncompressed layer. If the
+// underlying implementation doesn't implement UncompressedSize directly,
+// this will compute the uncompressedSize by reading everything returned
+// by Compressed(). This is potentially expensive and may consume the contents
+// for streaming layers.
+func UncompressedSize(l v1.Layer) (int64, error) {
+	// If the layer implements UncompressedSize itself, return that.
+	if wus, ok := l.(withUncompressedSize); ok {
+		return wus.UncompressedSize()
+	}
+
+	// Otherwise, try to unwrap any partial implementations to see
+	// if the wrapped struct implements UncompressedSize.
+	if ule, ok := l.(*uncompressedLayerExtender); ok {
+		if wus, ok := ule.UncompressedLayer.(withUncompressedSize); ok {
+			return wus.UncompressedSize()
+		}
+	}
+	if cle, ok := l.(*compressedLayerExtender); ok {
+		if wus, ok := cle.CompressedLayer.(withUncompressedSize); ok {
+			return wus.UncompressedSize()
+		}
+	}
+
+	// The layer doesn't implement UncompressedSize, we need to compute it.
+	rc, err := l.Uncompressed()
+	if err != nil {
+		return -1, err
+	}
+	defer rc.Close()
+
+	return io.Copy(ioutil.Discard, rc)
+}