1 files changed, 68 insertions, 0 deletions
diff --git a/pkg/v1/static/layer.go b/pkg/v1/static/layer.go
new file mode 100644
index 0000000..a4bbe69
--- /dev/null
+++ b/pkg/v1/static/layer.go
@@ -0,0 +1,68 @@
+// Copyright 2021 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 static
+
+import (
+	"bytes"
+	"io"
+	"sync"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+// NewLayer returns a layer containing the given bytes, with the given mediaType.
+//
+// Contents will not be compressed.
+func NewLayer(b []byte, mt types.MediaType) v1.Layer {
+	return &staticLayer{b: b, mt: mt}
+}
+
+type staticLayer struct {
+	b  []byte
+	mt types.MediaType
+
+	once sync.Once
+	h    v1.Hash
+}
+
+func (l *staticLayer) Digest() (v1.Hash, error) {
+	var err error
+	// Only calculate digest the first time we're asked.
+	l.once.Do(func() {
+		l.h, _, err = v1.SHA256(bytes.NewReader(l.b))
+	})
+	return l.h, err
+}
+
+func (l *staticLayer) DiffID() (v1.Hash, error) {
+	return l.Digest()
+}
+
+func (l *staticLayer) Compressed() (io.ReadCloser, error) {
+	return io.NopCloser(bytes.NewReader(l.b)), nil
+}
+
+func (l *staticLayer) Uncompressed() (io.ReadCloser, error) {
+	return io.NopCloser(bytes.NewReader(l.b)), nil
+}
+
+func (l *staticLayer) Size() (int64, error) {
+	return int64(len(l.b)), nil
+}
+
+func (l *staticLayer) MediaType() (types.MediaType, error) {
+	return l.mt, nil
+}