Have compareImageDestinationManifestEqual return a *copySingleImageRe…

…sult on a match

... so that the caller doesn't have to assemble it. Using a pointer-or-nil eliminates
a separate boolean.

Signed-off-by: Miloslav Trmač <[email protected]>

copy/single.go

@@ -179,19 +179,15 @@ func (c *copier) copySingleImage(ctx context.Context, unparsedImage *image.Unpar
 
  logrus.Debugf("Checking if we can skip copying: has signatures=%t, OCI encryption=%t, no manifest updates=%t", shouldUpdateSigs, destRequiresOciEncryption, noPendingManifestUpdates)
  if !shouldUpdateSigs && !destRequiresOciEncryption && noPendingManifestUpdates {
- isSrcDestManifestEqual, retManifest, retManifestType, retManifestDigest, err := ic.compareImageDestinationManifestEqual(ctx, targetInstance)
+ matchedResult, err := ic.compareImageDestinationManifestEqual(ctx, targetInstance)
  if err != nil {
  logrus.Warnf("Failed to compare destination image manifest: %v", err)
  return copySingleImageResult{}, err
  }
 
- if isSrcDestManifestEqual {
+ if matchedResult != nil {
  c.Printf("Skipping: image already present at destination\n")
- return copySingleImageResult{
- manifest: retManifest,
- manifestMIMEType: retManifestType,
- manifestDigest: retManifestDigest,
- }, nil
+ return *matchedResult, nil
  }
  }
  }
@@ -336,38 +332,42 @@ func (ic *imageCopier) noPendingManifestUpdates() bool {
 }
 
 // compareImageDestinationManifestEqual compares the source and destination image manifests (reading the manifest from the
-// (possibly remote) destination). Returning true and the destination's manifest, type and digest if they compare equal.
-func (ic *imageCopier) compareImageDestinationManifestEqual(ctx context.Context, targetInstance *digest.Digest) (bool, []byte, string, digest.Digest, error) {
+// (possibly remote) destination). If they are equal, it returns a full copySingleImageResult, nil otherwise.
+func (ic *imageCopier) compareImageDestinationManifestEqual(ctx context.Context, targetInstance *digest.Digest) (*copySingleImageResult, error) {
  srcManifestDigest, err := manifest.Digest(ic.src.ManifestBlob)
  if err != nil {
- return false, nil, "", "", fmt.Errorf("calculating manifest digest: %w", err)
+ return nil, fmt.Errorf("calculating manifest digest: %w", err)
  }
 
  destImageSource, err := ic.c.dest.Reference().NewImageSource(ctx, ic.c.options.DestinationCtx)
  if err != nil {
  logrus.Debugf("Unable to create destination image %s source: %v", ic.c.dest.Reference(), err)
- return false, nil, "", "", nil
+ return nil, nil
  }
  defer destImageSource.Close()
 
  destManifest, destManifestType, err := destImageSource.GetManifest(ctx, targetInstance)
  if err != nil {
  logrus.Debugf("Unable to get destination image %s/%s manifest: %v", destImageSource, targetInstance, err)
- return false, nil, "", "", nil
+ return nil, nil
  }
 
  destManifestDigest, err := manifest.Digest(destManifest)
  if err != nil {
- return false, nil, "", "", fmt.Errorf("calculating manifest digest: %w", err)
+ return nil, fmt.Errorf("calculating manifest digest: %w", err)
  }
 
  logrus.Debugf("Comparing source and destination manifest digests: %v vs. %v", srcManifestDigest, destManifestDigest)
  if srcManifestDigest != destManifestDigest {
- return false, nil, "", "", nil
+ return nil, nil
  }
 
  // Destination and source manifests, types and digests should all be equivalent
- return true, destManifest, destManifestType, destManifestDigest, nil
+ return &copySingleImageResult{
+ manifest: destManifest,
+ manifestMIMEType: destManifestType,
+ manifestDigest: srcManifestDigest,
+ }, nil
 }
 
 // copyLayers copies layers from ic.src/ic.c.rawSource to dest, using and updating ic.manifestUpdates if necessary and ic.cannotModifyManifestReason == "".