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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 partial
import (
"io"
"github.com/google/go-containerregistry/internal/and"
"github.com/google/go-containerregistry/internal/compression"
"github.com/google/go-containerregistry/internal/gzip"
"github.com/google/go-containerregistry/internal/zstd"
comp "github.com/google/go-containerregistry/pkg/compression"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/types"
)
// 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) {
rc, err := cle.Compressed()
if err != nil {
return nil, err
}
// Often, the "compressed" bytes are not actually-compressed.
// Peek at the first two bytes to determine whether it's correct to
// wrap this with gzip.UnzipReadCloser or zstd.UnzipReadCloser.
cp, pr, err := compression.PeekCompression(rc)
if err != nil {
return nil, err
}
prc := &and.ReadCloser{
Reader: pr,
CloseFunc: rc.Close,
}
switch cp {
case comp.GZip:
return gzip.UnzipReadCloser(prc)
case comp.ZStd:
return zstd.UnzipReadCloser(prc)
default:
return prc, nil
}
}
// 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
}
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