1 files changed, 203 insertions, 0 deletions
diff --git a/pkg/v1/daemon/image.go b/pkg/v1/daemon/image.go
new file mode 100644
index 0000000..55ba833
--- /dev/null
+++ b/pkg/v1/daemon/image.go
@@ -0,0 +1,203 @@
+// 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 daemon
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"sync"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+type image struct {
+	ref          name.Reference
+	opener       *imageOpener
+	tarballImage v1.Image
+	id           *v1.Hash
+
+	once sync.Once
+	err  error
+}
+
+type imageOpener struct {
+	ref name.Reference
+	ctx context.Context
+
+	buffered bool
+	client   Client
+
+	once  sync.Once
+	bytes []byte
+	err   error
+}
+
+func (i *imageOpener) saveImage() (io.ReadCloser, error) {
+	return i.client.ImageSave(i.ctx, []string{i.ref.Name()})
+}
+
+func (i *imageOpener) bufferedOpener() (io.ReadCloser, error) {
+	// Store the tarball in memory and return a new reader into the bytes each time we need to access something.
+	i.once.Do(func() {
+		i.bytes, i.err = func() ([]byte, error) {
+			rc, err := i.saveImage()
+			if err != nil {
+				return nil, err
+			}
+			defer rc.Close()
+
+			return io.ReadAll(rc)
+		}()
+	})
+
+	// Wrap the bytes in a ReadCloser so it looks like an opened file.
+	return io.NopCloser(bytes.NewReader(i.bytes)), i.err
+}
+
+func (i *imageOpener) opener() tarball.Opener {
+	if i.buffered {
+		return i.bufferedOpener
+	}
+
+	// To avoid storing the tarball in memory, do a save every time we need to access something.
+	return i.saveImage
+}
+
+// Image provides access to an image reference from the Docker daemon,
+// applying functional options to the underlying imageOpener before
+// resolving the reference into a v1.Image.
+func Image(ref name.Reference, options ...Option) (v1.Image, error) {
+	o, err := makeOptions(options...)
+	if err != nil {
+		return nil, err
+	}
+
+	i := &imageOpener{
+		ref:      ref,
+		buffered: o.buffered,
+		client:   o.client,
+		ctx:      o.ctx,
+	}
+
+	img := &image{
+		ref:    ref,
+		opener: i,
+	}
+
+	// Eagerly fetch Image ID to ensure it actually exists.
+	// https://github.com/google/go-containerregistry/issues/1186
+	id, err := img.ConfigName()
+	if err != nil {
+		return nil, err
+	}
+	img.id = &id
+
+	return img, nil
+}
+
+func (i *image) initialize() error {
+	// Don't re-initialize tarball if already initialized.
+	if i.tarballImage == nil {
+		i.once.Do(func() {
+			i.tarballImage, i.err = tarball.Image(i.opener.opener(), nil)
+		})
+	}
+	return i.err
+}
+
+func (i *image) Layers() ([]v1.Layer, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.Layers()
+}
+
+func (i *image) MediaType() (types.MediaType, error) {
+	if err := i.initialize(); err != nil {
+		return "", err
+	}
+	return i.tarballImage.MediaType()
+}
+
+func (i *image) Size() (int64, error) {
+	if err := i.initialize(); err != nil {
+		return 0, err
+	}
+	return i.tarballImage.Size()
+}
+
+func (i *image) ConfigName() (v1.Hash, error) {
+	if i.id != nil {
+		return *i.id, nil
+	}
+	res, _, err := i.opener.client.ImageInspectWithRaw(i.opener.ctx, i.ref.String())
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	return v1.NewHash(res.ID)
+}
+
+func (i *image) ConfigFile() (*v1.ConfigFile, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.ConfigFile()
+}
+
+func (i *image) RawConfigFile() ([]byte, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.RawConfigFile()
+}
+
+func (i *image) Digest() (v1.Hash, error) {
+	if err := i.initialize(); err != nil {
+		return v1.Hash{}, err
+	}
+	return i.tarballImage.Digest()
+}
+
+func (i *image) Manifest() (*v1.Manifest, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.Manifest()
+}
+
+func (i *image) RawManifest() ([]byte, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.RawManifest()
+}
+
+func (i *image) LayerByDigest(h v1.Hash) (v1.Layer, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.LayerByDigest(h)
+}
+
+func (i *image) LayerByDiffID(h v1.Hash) (v1.Layer, error) {
+	if err := i.initialize(); err != nil {
+		return nil, err
+	}
+	return i.tarballImage.LayerByDiffID(h)
+}