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// 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 layout
import (
"encoding/json"
"errors"
"fmt"
"io"
"os"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/partial"
"github.com/google/go-containerregistry/pkg/v1/types"
)
var _ v1.ImageIndex = (*layoutIndex)(nil)
type layoutIndex struct {
mediaType types.MediaType
path Path
rawIndex []byte
}
// ImageIndexFromPath is a convenience function which constructs a Path and returns its v1.ImageIndex.
func ImageIndexFromPath(path string) (v1.ImageIndex, error) {
lp, err := FromPath(path)
if err != nil {
return nil, err
}
return lp.ImageIndex()
}
// ImageIndex returns a v1.ImageIndex for the Path.
func (l Path) ImageIndex() (v1.ImageIndex, error) {
rawIndex, err := os.ReadFile(l.path("index.json"))
if err != nil {
return nil, err
}
idx := &layoutIndex{
mediaType: types.OCIImageIndex,
path: l,
rawIndex: rawIndex,
}
return idx, nil
}
func (i *layoutIndex) MediaType() (types.MediaType, error) {
return i.mediaType, nil
}
func (i *layoutIndex) Digest() (v1.Hash, error) {
return partial.Digest(i)
}
func (i *layoutIndex) Size() (int64, error) {
return partial.Size(i)
}
func (i *layoutIndex) IndexManifest() (*v1.IndexManifest, error) {
var index v1.IndexManifest
err := json.Unmarshal(i.rawIndex, &index)
return &index, err
}
func (i *layoutIndex) RawManifest() ([]byte, error) {
return i.rawIndex, nil
}
func (i *layoutIndex) Image(h v1.Hash) (v1.Image, error) {
// Look up the digest in our manifest first to return a better error.
desc, err := i.findDescriptor(h)
if err != nil {
return nil, err
}
if !isExpectedMediaType(desc.MediaType, types.OCIManifestSchema1, types.DockerManifestSchema2) {
return nil, fmt.Errorf("unexpected media type for %v: %s", h, desc.MediaType)
}
img := &layoutImage{
path: i.path,
desc: *desc,
}
return partial.CompressedToImage(img)
}
func (i *layoutIndex) ImageIndex(h v1.Hash) (v1.ImageIndex, error) {
// Look up the digest in our manifest first to return a better error.
desc, err := i.findDescriptor(h)
if err != nil {
return nil, err
}
if !isExpectedMediaType(desc.MediaType, types.OCIImageIndex, types.DockerManifestList) {
return nil, fmt.Errorf("unexpected media type for %v: %s", h, desc.MediaType)
}
rawIndex, err := i.path.Bytes(h)
if err != nil {
return nil, err
}
return &layoutIndex{
mediaType: desc.MediaType,
path: i.path,
rawIndex: rawIndex,
}, nil
}
func (i *layoutIndex) Blob(h v1.Hash) (io.ReadCloser, error) {
return i.path.Blob(h)
}
func (i *layoutIndex) findDescriptor(h v1.Hash) (*v1.Descriptor, error) {
im, err := i.IndexManifest()
if err != nil {
return nil, err
}
if h == (v1.Hash{}) {
if len(im.Manifests) != 1 {
return nil, errors.New("oci layout must contain only a single image to be used with layout.Image")
}
return &(im.Manifests)[0], nil
}
for _, desc := range im.Manifests {
if desc.Digest == h {
return &desc, nil
}
}
return nil, fmt.Errorf("could not find descriptor in index: %s", h)
}
// TODO: Pull this out into methods on types.MediaType? e.g. instead, have:
// * mt.IsIndex()
// * mt.IsImage()
func isExpectedMediaType(mt types.MediaType, expected ...types.MediaType) bool {
for _, allowed := range expected {
if mt == allowed {
return true
}
}
return false
}
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