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// Copyright 2023 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 platform
import (
"fmt"
"strings"
v1 "github.com/google/go-containerregistry/pkg/v1"
"github.com/sigstore/cosign/v2/pkg/oci"
)
type List []struct {
Hash v1.Hash
Platform *v1.Platform
}
func (pl *List) String() string {
r := []string{}
for _, p := range *pl {
r = append(r, p.Platform.String())
}
return strings.Join(r, ", ")
}
func GetIndexPlatforms(idx oci.SignedImageIndex) (List, error) {
im, err := idx.IndexManifest()
if err != nil {
return nil, fmt.Errorf("fetching index manifest: %w", err)
}
platforms := List{}
for _, m := range im.Manifests {
if m.Platform == nil {
continue
}
platforms = append(platforms, struct {
Hash v1.Hash
Platform *v1.Platform
}{m.Digest, m.Platform})
}
return platforms, nil
}
// matchPlatform filters a list of platforms returning only those matching
// a base. "Based" on ko's internal equivalent while it moves to GGCR.
// https://github.com/google/ko/blob/e6a7a37e26d82a8b2bb6df991c5a6cf6b2728794/pkg/build/gobuild.go#L1020
func matchPlatform(base *v1.Platform, list List) List {
ret := List{}
for _, p := range list {
if base.OS != "" && base.OS != p.Platform.OS {
continue
}
if base.Architecture != "" && base.Architecture != p.Platform.Architecture {
continue
}
if base.Variant != "" && base.Variant != p.Platform.Variant {
continue
}
if base.OSVersion != "" && p.Platform.OSVersion != base.OSVersion {
if base.OS != "windows" {
continue
} else { //nolint: revive
if pcount, bcount := strings.Count(base.OSVersion, "."), strings.Count(p.Platform.OSVersion, "."); pcount == 2 && bcount == 3 {
if base.OSVersion != p.Platform.OSVersion[:strings.LastIndex(p.Platform.OSVersion, ".")] {
continue
}
} else {
continue
}
}
}
ret = append(ret, p)
}
return ret
}
func SignedEntityForPlatform(se oci.SignedEntity, platform string) (oci.SignedEntity, error) {
if platform == "" {
// Copy all platforms
return se, nil
}
idx, isIndex := se.(oci.SignedImageIndex)
// We only allow --platform on multiarch indexes
if !isIndex {
return nil, fmt.Errorf("specified reference is not a multiarch image")
}
targetPlatform, err := v1.ParsePlatform(platform)
if err != nil {
return nil, fmt.Errorf("parsing platform: %w", err)
}
platforms, err := GetIndexPlatforms(idx)
if err != nil {
return nil, fmt.Errorf("getting available platforms: %w", err)
}
platforms = matchPlatform(targetPlatform, platforms)
if len(platforms) == 0 {
return nil, fmt.Errorf("unable to find an entity for %s", targetPlatform.String())
}
if len(platforms) > 1 {
return nil, fmt.Errorf(
"platform spec matches more than one image architecture: %s",
platforms.String(),
)
}
nse, err := idx.SignedImage(platforms[0].Hash)
if err != nil {
return nil, fmt.Errorf("searching for %s image: %w", platforms[0].Hash.String(), err)
}
if nse == nil {
return nil, fmt.Errorf("unable to find image %s", platforms[0].Hash.String())
}
return nse, nil
}
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