forked from containers/image
/
directory_src.go
96 lines (85 loc) · 3.58 KB
/
directory_src.go
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package directory
import (
"context"
"io"
"io/ioutil"
"os"
"github.com/containers/image/manifest"
"github.com/containers/image/types"
"github.com/opencontainers/go-digest"
"github.com/pkg/errors"
)
type dirImageSource struct {
ref dirReference
}
// newImageSource returns an ImageSource reading from an existing directory.
// The caller must call .Close() on the returned ImageSource.
func newImageSource(ref dirReference) types.ImageSource {
return &dirImageSource{ref}
}
// Reference returns the reference used to set up this source, _as specified by the user_
// (not as the image itself, or its underlying storage, claims). This can be used e.g. to determine which public keys are trusted for this image.
func (s *dirImageSource) Reference() types.ImageReference {
return s.ref
}
// Close removes resources associated with an initialized ImageSource, if any.
func (s *dirImageSource) Close() error {
return nil
}
// 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).
// It may use a remote (= slow) service.
// If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve (when the primary manifest is a manifest list);
// this never happens if the primary manifest is not a manifest list (e.g. if the source never returns manifest lists).
func (s *dirImageSource) GetManifest(ctx context.Context, instanceDigest *digest.Digest) ([]byte, string, error) {
if instanceDigest != nil {
return nil, "", errors.Errorf(`Getting target manifest not supported by "dir:"`)
}
m, err := ioutil.ReadFile(s.ref.manifestPath())
if err != nil {
return nil, "", err
}
return m, manifest.GuessMIMEType(m), err
}
// HasThreadSafeGetBlob indicates whether GetBlob can be executed concurrently.
func (s *dirImageSource) HasThreadSafeGetBlob() bool {
return false
}
// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
// The Digest field in BlobInfo is guaranteed to be provided, Size may be -1 and MediaType may be optionally provided.
// May update BlobInfoCache, preferably after it knows for certain that a blob truly exists at a specific location.
func (s *dirImageSource) GetBlob(ctx context.Context, info types.BlobInfo, cache types.BlobInfoCache) (io.ReadCloser, int64, error) {
r, err := os.Open(s.ref.layerPath(info.Digest))
if err != nil {
return nil, -1, err
}
fi, err := r.Stat()
if err != nil {
return nil, -1, err
}
return r, fi.Size(), nil
}
// GetSignatures returns the image's signatures. It may use a remote (= slow) service.
// If instanceDigest is not nil, it contains a digest of the specific manifest instance to retrieve signatures for
// (when the primary manifest is a manifest list); this never happens if the primary manifest is not a manifest list
// (e.g. if the source never returns manifest lists).
func (s *dirImageSource) GetSignatures(ctx context.Context, instanceDigest *digest.Digest) ([][]byte, error) {
if instanceDigest != nil {
return nil, errors.Errorf(`Manifests lists are not supported by "dir:"`)
}
signatures := [][]byte{}
for i := 0; ; i++ {
signature, err := ioutil.ReadFile(s.ref.signaturePath(i))
if err != nil {
if os.IsNotExist(err) {
break
}
return nil, err
}
signatures = append(signatures, signature)
}
return signatures, nil
}
// LayerInfosForCopy() returns updated layer info that should be used when copying, in preference to values in the manifest, if specified.
func (s *dirImageSource) LayerInfosForCopy(ctx context.Context) ([]types.BlobInfo, error) {
return nil, nil
}