1 files changed, 114 insertions, 0 deletions
diff --git a/pkg/crane/append.go b/pkg/crane/append.go
new file mode 100644
index 0000000..f1c2ef6
--- /dev/null
+++ b/pkg/crane/append.go
@@ -0,0 +1,114 @@
+// Copyright 2018 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 crane
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/google/go-containerregistry/internal/windows"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/stream"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+func isWindows(img v1.Image) (bool, error) {
+	cfg, err := img.ConfigFile()
+	if err != nil {
+		return false, err
+	}
+	return cfg != nil && cfg.OS == "windows", nil
+}
+
+// Append reads a layer from path and appends it the the v1.Image base.
+//
+// If the base image is a Windows base image (i.e., its config.OS is
+// "windows"), the contents of the tarballs will be modified to be suitable for
+// a Windows container image.`,
+func Append(base v1.Image, paths ...string) (v1.Image, error) {
+	if base == nil {
+		return nil, fmt.Errorf("invalid argument: base")
+	}
+
+	win, err := isWindows(base)
+	if err != nil {
+		return nil, fmt.Errorf("getting base image: %w", err)
+	}
+
+	baseMediaType, err := base.MediaType()
+
+	if err != nil {
+		return nil, fmt.Errorf("getting base image media type: %w", err)
+	}
+
+	layerType := types.DockerLayer
+
+	if baseMediaType == types.OCIManifestSchema1 {
+		layerType = types.OCILayer
+	}
+
+	layers := make([]v1.Layer, 0, len(paths))
+	for _, path := range paths {
+		layer, err := getLayer(path, layerType)
+		if err != nil {
+			return nil, fmt.Errorf("reading layer %q: %w", path, err)
+		}
+
+		if win {
+			layer, err = windows.Windows(layer)
+			if err != nil {
+				return nil, fmt.Errorf("converting %q for Windows: %w", path, err)
+			}
+		}
+
+		layers = append(layers, layer)
+	}
+
+	return mutate.AppendLayers(base, layers...)
+}
+
+func getLayer(path string, layerType types.MediaType) (v1.Layer, error) {
+	f, err := streamFile(path)
+	if err != nil {
+		return nil, err
+	}
+	if f != nil {
+		return stream.NewLayer(f, stream.WithMediaType(layerType)), nil
+	}
+
+	return tarball.LayerFromFile(path, tarball.WithMediaType(layerType))
+}
+
+// If we're dealing with a named pipe, trying to open it multiple times will
+// fail, so we need to do a streaming upload.
+//
+// returns nil, nil for non-streaming files
+func streamFile(path string) (*os.File, error) {
+	if path == "-" {
+		return os.Stdin, nil
+	}
+	fi, err := os.Stat(path)
+	if err != nil {
+		return nil, err
+	}
+
+	if !fi.Mode().IsRegular() {
+		return os.Open(path)
+	}
+
+	return nil, nil
+}