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//
// Copyright 2021 The Sigstore Authors.
//
// 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 layout
import (
"fmt"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/google/go-containerregistry/pkg/v1/empty"
"github.com/google/go-containerregistry/pkg/v1/layout"
"github.com/sigstore/cosign/v2/pkg/oci"
)
// WriteSignedImage writes the image and all related signatures, attestations and attachments
func WriteSignedImage(path string, si oci.SignedImage) error {
// First, write an empty index
layoutPath, err := layout.Write(path, empty.Index)
if err != nil {
return err
}
// write the image
if err := appendImage(layoutPath, si, imageAnnotation); err != nil {
return fmt.Errorf("appending signed image: %w", err)
}
return writeSignedEntity(layoutPath, si)
}
// WriteSignedImageIndex writes the image index and all related signatures, attestations and attachments
func WriteSignedImageIndex(path string, si oci.SignedImageIndex) error {
// First, write an empty index
layoutPath, err := layout.Write(path, empty.Index)
if err != nil {
return err
}
// write the image index
if err := layoutPath.AppendIndex(si, layout.WithAnnotations(
map[string]string{kindAnnotation: imageIndexAnnotation},
)); err != nil {
return fmt.Errorf("appending signed image index: %w", err)
}
return writeSignedEntity(layoutPath, si)
}
func writeSignedEntity(path layout.Path, se oci.SignedEntity) error {
// write the signatures
sigs, err := se.Signatures()
if err != nil {
return fmt.Errorf("getting signatures: %w", err)
}
if !isEmpty(sigs) {
if err := appendImage(path, sigs, sigsAnnotation); err != nil {
return fmt.Errorf("appending signatures: %w", err)
}
}
// write attestations
atts, err := se.Attestations()
if err != nil {
return fmt.Errorf("getting atts")
}
if !isEmpty(atts) {
if err := appendImage(path, atts, attsAnnotation); err != nil {
return fmt.Errorf("appending atts: %w", err)
}
}
// TODO (priyawadhwa@) and attachments
return nil
}
// isEmpty returns true if the signatures or attestations are empty
func isEmpty(s oci.Signatures) bool {
ss, _ := s.Get()
return ss == nil
}
func appendImage(path layout.Path, img v1.Image, annotation string) error {
return path.AppendImage(img, layout.WithAnnotations(
map[string]string{kindAnnotation: annotation},
))
}
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