98 lines
2.4 KiB
Go
98 lines
2.4 KiB
Go
package layout
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import (
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"encoding/json"
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"io"
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"io/ioutil"
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"os"
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"github.com/containers/image/types"
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"github.com/opencontainers/go-digest"
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imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
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)
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type ociImageSource struct {
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ref ociReference
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}
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// newImageSource returns an ImageSource for reading from an existing directory.
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func newImageSource(ref ociReference) types.ImageSource {
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return &ociImageSource{ref: ref}
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}
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// Reference returns the reference used to set up this source.
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func (s *ociImageSource) Reference() types.ImageReference {
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return s.ref
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}
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// Close removes resources associated with an initialized ImageSource, if any.
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func (s *ociImageSource) Close() error {
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return nil
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}
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// GetManifest returns the image's manifest along with its MIME type (which may be empty when it can't be determined but the manifest is available).
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// It may use a remote (= slow) service.
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func (s *ociImageSource) GetManifest() ([]byte, string, error) {
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descriptorPath := s.ref.descriptorPath(s.ref.tag)
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data, err := ioutil.ReadFile(descriptorPath)
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if err != nil {
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return nil, "", err
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}
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desc := imgspecv1.Descriptor{}
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err = json.Unmarshal(data, &desc)
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if err != nil {
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return nil, "", err
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}
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manifestPath, err := s.ref.blobPath(digest.Digest(desc.Digest))
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if err != nil {
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return nil, "", err
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}
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m, err := ioutil.ReadFile(manifestPath)
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if err != nil {
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return nil, "", err
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}
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return m, desc.MediaType, nil
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}
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func (s *ociImageSource) GetTargetManifest(digest digest.Digest) ([]byte, string, error) {
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manifestPath, err := s.ref.blobPath(digest)
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if err != nil {
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return nil, "", err
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}
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m, err := ioutil.ReadFile(manifestPath)
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if err != nil {
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return nil, "", err
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}
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// XXX: GetTargetManifest means that we don't have the context of what
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// mediaType the manifest has. In OCI this means that we don't know
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// what reference it came from, so we just *assume* that its
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// MediaTypeImageManifest.
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return m, imgspecv1.MediaTypeImageManifest, nil
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}
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// GetBlob returns a stream for the specified blob, and the blob's size.
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func (s *ociImageSource) GetBlob(info types.BlobInfo) (io.ReadCloser, int64, error) {
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path, err := s.ref.blobPath(info.Digest)
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if err != nil {
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return nil, 0, err
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}
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r, err := os.Open(path)
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if err != nil {
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return nil, 0, err
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}
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fi, err := r.Stat()
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if err != nil {
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return nil, 0, err
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}
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return r, fi.Size(), nil
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}
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func (s *ociImageSource) GetSignatures() ([][]byte, error) {
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return [][]byte{}, nil
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}
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