OCI source: return error if open blob failed

Signed-off-by: Ye Yin <eyniy@qq.com>

oci/layout/oci_src.go

@@ -70,7 +70,7 @@ func (s *ociImageSource) GetTargetManifest(digest string) ([]byte, string, error
 	return m, manifest.GuessMIMEType(m), nil
 }
 
-// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
+// GetBlob returns a stream for the specified blob, and the blob's size.
 func (s *ociImageSource) GetBlob(digest string) (io.ReadCloser, int64, error) {
 	path, err := s.ref.blobPath(digest)
 	if err != nil {
@@ -79,11 +79,11 @@ func (s *ociImageSource) GetBlob(digest string) (io.ReadCloser, int64, error) {
 
 	r, err := os.Open(path)
 	if err != nil {
-		return nil, 0, nil
+		return nil, 0, err
 	}
 	fi, err := r.Stat()
 	if err != nil {
-		return nil, 0, nil
+		return nil, 0, err
 	}
 	return r, fi.Size(), nil
 }

types/types.go

@@ -186,7 +186,7 @@ type Image interface {
 	// ConfigInfo returns a complete BlobInfo for the separate config object, or a BlobInfo{Digest:""} if there isn't a separate object.
 	// Note that the config object may not exist in the underlying storage in the return value of UpdatedImage! Use ConfigBlob() below.
 	ConfigInfo() BlobInfo
-	// ConfigBlob returns the blob described by ConfigInfo, iff ConfigInfo().Digest != ""; nil otherwise.
+	// ConfigBlob returns the blob described by ConfigInfo, if ConfigInfo().Digest != ""; nil otherwise.
 	// The result is cached; it is OK to call this however often you need.
 	ConfigBlob() ([]byte, error)
 	// LayerInfos returns a list of BlobInfos of layers referenced by this image, in order (the root layer first, and then successive layered layers).