1 files changed, 223 insertions, 0 deletions
diff --git a/pkg/v1/partial/uncompressed.go b/pkg/v1/partial/uncompressed.go
new file mode 100644
index 0000000..df20d3a
--- /dev/null
+++ b/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"
+
+	"github.com/google/go-containerregistry/internal/gzip"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+// 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 gzip.ReadCloser(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)
+}