Crypto library movement and changes to content helper interfaces

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

images/image.go

@@ -64,9 +64,6 @@ type DeleteOptions struct {
 // DeleteOpt allows configuring a delete operation
 type DeleteOpt func(context.Context, *DeleteOptions) error
 
-// LayerFilter allows to select Layers by certain criteria
-type LayerFilter func(desc ocispec.Descriptor) bool
-
 // SynchronousDelete is used to indicate that an image deletion and removal of
 // the image resources should occur synchronously before returning a result.
 func SynchronousDelete() DeleteOpt {
@@ -89,14 +86,6 @@ type Store interface {
 	Delete(ctx context.Context, name string, opts ...DeleteOpt) error
 }
 
-type cryptoOp int
-
-const (
-	cryptoOpEncrypt    cryptoOp = iota
-	cryptoOpDecrypt             = iota
-	cryptoOpUnwrapOnly          = iota
-)
-
 // TODO(stevvooe): Many of these functions make strong platform assumptions,
 // which are untrue in a lot of cases. More refactoring must be done here to
 // make this work in all cases.
@@ -408,7 +397,7 @@ func RootFS(ctx context.Context, provider content.Provider, configDesc ocispec.D
 func IsCompressedDiff(ctx context.Context, mediaType string) (bool, error) {
 	switch mediaType {
 	case ocispec.MediaTypeImageLayer, MediaTypeDockerSchema2Layer:
-	case ocispec.MediaTypeImageLayerGzip, MediaTypeDockerSchema2LayerGzip, MediaTypeDockerSchema2LayerGzipEnc:
+	case ocispec.MediaTypeImageLayerGzip, MediaTypeDockerSchema2LayerGzip:
 		return true, nil
 	default:
 		// Still apply all generic media types *.tar[.+]gzip and *.tar
@@ -447,13 +436,17 @@ func GetImageLayerDescriptors(ctx context.Context, cs content.Store, desc ocispe
 		for _, child := range children {
 			var tmp []ocispec.Descriptor
 
-			if isDescriptorALayer(child) {
+			switch child.MediaType {
+			case MediaTypeDockerSchema2LayerGzip, MediaTypeDockerSchema2Layer,
+				ocispec.MediaTypeImageLayerGzip, ocispec.MediaTypeImageLayer,
+				MediaTypeDockerSchema2LayerGzipEnc, MediaTypeDockerSchema2LayerEnc:
 				tdesc := child
 				tdesc.Platform = platform
 				tmp = append(tmp, tdesc)
-			} else {
+			default:
 				tmp, err = GetImageLayerDescriptors(ctx, cs, child)
 			}
+
 			if err != nil {
 				return []ocispec.Descriptor{}, err
 			}