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