1 files changed, 85 insertions, 0 deletions
diff --git a/pkg/v1/partial/index.go b/pkg/v1/partial/index.go
new file mode 100644
index 0000000..f17f274
--- /dev/null
+++ b/pkg/v1/partial/index.go
@@ -0,0 +1,85 @@
+// Copyright 2020 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 partial
+
+import (
+	"fmt"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/match"
+)
+
+// FindManifests given a v1.ImageIndex, find the manifests that fit the matcher.
+func FindManifests(index v1.ImageIndex, matcher match.Matcher) ([]v1.Descriptor, error) {
+	// get the actual manifest list
+	indexManifest, err := index.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("unable to get raw index: %w", err)
+	}
+	manifests := []v1.Descriptor{}
+	// try to get the root of our image
+	for _, manifest := range indexManifest.Manifests {
+		if matcher(manifest) {
+			manifests = append(manifests, manifest)
+		}
+	}
+	return manifests, nil
+}
+
+// FindImages given a v1.ImageIndex, find the images that fit the matcher. If a Descriptor
+// matches the provider Matcher, but the referenced item is not an Image, ignores it.
+// Only returns those that match the Matcher and are images.
+func FindImages(index v1.ImageIndex, matcher match.Matcher) ([]v1.Image, error) {
+	matches := []v1.Image{}
+	manifests, err := FindManifests(index, matcher)
+	if err != nil {
+		return nil, err
+	}
+	for _, desc := range manifests {
+		// if it is not an image, ignore it
+		if !desc.MediaType.IsImage() {
+			continue
+		}
+		img, err := index.Image(desc.Digest)
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, img)
+	}
+	return matches, nil
+}
+
+// FindIndexes given a v1.ImageIndex, find the indexes that fit the matcher. If a Descriptor
+// matches the provider Matcher, but the referenced item is not an Index, ignores it.
+// Only returns those that match the Matcher and are indexes.
+func FindIndexes(index v1.ImageIndex, matcher match.Matcher) ([]v1.ImageIndex, error) {
+	matches := []v1.ImageIndex{}
+	manifests, err := FindManifests(index, matcher)
+	if err != nil {
+		return nil, err
+	}
+	for _, desc := range manifests {
+		if !desc.MediaType.IsIndex() {
+			continue
+		}
+		// if it is not an index, ignore it
+		idx, err := index.ImageIndex(desc.Digest)
+		if err != nil {
+			return nil, err
+		}
+		matches = append(matches, idx)
+	}
+	return matches, nil
+}