1 files changed, 57 insertions, 0 deletions
diff --git a/internal/legacy/copy.go b/internal/legacy/copy.go
new file mode 100644
index 0000000..10467ba
--- /dev/null
+++ b/internal/legacy/copy.go
@@ -0,0 +1,57 @@
+// Copyright 2019 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package legacy provides methods for interacting with legacy image formats.
+package legacy
+
+import (
+	"bytes"
+	"encoding/json"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+// CopySchema1 allows `[g]crane cp` to work with old images without adding
+// full support for schema 1 images to this package.
+func CopySchema1(desc *remote.Descriptor, srcRef, dstRef name.Reference, opts ...remote.Option) error {
+	m := schema1{}
+	if err := json.NewDecoder(bytes.NewReader(desc.Manifest)).Decode(&m); err != nil {
+		return err
+	}
+
+	for _, layer := range m.FSLayers {
+		src := srcRef.Context().Digest(layer.BlobSum)
+		dst := dstRef.Context().Digest(layer.BlobSum)
+
+		blob, err := remote.Layer(src, opts...)
+		if err != nil {
+			return err
+		}
+
+		if err := remote.WriteLayer(dst.Context(), blob, opts...); err != nil {
+			return err
+		}
+	}
+
+	return remote.Put(dstRef, desc, opts...)
+}
+
+type fslayer struct {
+	BlobSum string `json:"blobSum"`
+}
+
+type schema1 struct {
+	FSLayers []fslayer `json:"fsLayers"`
+}