func manifestInstanceFromBlob(ctx context.Context, sys *types.SystemContext, src types.ImageSource, manblob []byte, mt string) (genericManifest, error) {
	switch manifest.NormalizedMIMEType(mt) {
	case manifest.DockerV2Schema1MediaType, manifest.DockerV2Schema1SignedMediaType:
		return manifestSchema1FromManifest(manblob)
	case imgspecv1.MediaTypeImageManifest:
		return manifestOCI1FromManifest(src, manblob)
	case manifest.DockerV2Schema2MediaType:
		return manifestSchema2FromManifest(src, manblob)
	case manifest.DockerV2ListMediaType:
		return manifestSchema2FromManifestList(ctx, sys, src, manblob)
	default: // Note that this may not be reachable, manifest.NormalizedMIMEType has a default for unknown values.
		return nil, fmt.Errorf("Unimplemented manifest MIME type %s", mt)
	}
}
func manifestInstanceFromBlob(ctx context.Context, sys *types.SystemContext, src types.ImageSource, manblob []byte, mt string) (genericManifest, error) {
	switch manifest.NormalizedMIMEType(mt) {
	case manifest.DockerV2Schema1MediaType, manifest.DockerV2Schema1SignedMediaType:
		return manifestSchema1FromManifest(manblob)
	case imgspecv1.MediaTypeImageManifest:
		return manifestOCI1FromManifest(src, manblob)
	case manifest.DockerV2Schema2MediaType:
		return manifestSchema2FromManifest(src, manblob)
	case manifest.DockerV2ListMediaType:
		return manifestSchema2FromManifestList(ctx, sys, src, manblob)
	default: // Note that this may not be reachable, manifest.NormalizedMIMEType has a default for unknown values.
		return nil, fmt.Errorf("Unimplemented manifest MIME type %s", mt)
	}
}
// manifestInstanceFromBlob returns a genericManifest implementation for (manblob, mt) in src.
// If manblob is a manifest list, it implicitly chooses an appropriate image from the list.