Improve image ID lookup for pulled images

- Use the image's repo, not just the digest, to be more precise
  when zstd:chunked ambiguities are involved
- Remove the multi-platform lookup code, it is never used

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

libimage/pull.go

@@ -25,7 +25,6 @@ import (
 	"github.com/containers/image/v5/transports/alltransports"
 	"github.com/containers/image/v5/types"
 	"github.com/containers/storage"
-	digest "github.com/opencontainers/go-digest"
 	ociSpec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/sirupsen/logrus"
 )
@@ -457,52 +456,38 @@ func (r *Runtime) copyFromRegistry(ctx context.Context, ref types.ImageReference
 	return pulledIDs, nil
 }
 
-// imageIDForManifest() parses the manifest of the copied image and then looks
-// up the ID of the matching image.  There's a small slice of time, between
-// when we copy the image into local storage and when we go to look for it
-// using the name that we gave it when we copied it, when the name we wanted to
-// assign to the image could have been moved, but the image's ID will remain
-// the same until it is deleted.
-func (r *Runtime) imageIDForManifest(manifestBytes []byte, sys *types.SystemContext) (string, error) {
-	var imageDigest digest.Digest
-	manifestType := manifest.GuessMIMEType(manifestBytes)
-	if manifest.MIMETypeIsMultiImage(manifestType) {
-		list, err := manifest.ListFromBlob(manifestBytes, manifestType)
-		if err != nil {
-			return "", fmt.Errorf("parsing manifest list: %w", err)
-		}
-		d, err := list.ChooseInstance(sys)
-		if err != nil {
-			return "", fmt.Errorf("choosing instance from manifest list: %w", err)
-		}
-		imageDigest = d
-	} else {
-		d, err := manifest.Digest(manifestBytes)
-		if err != nil {
-			return "", errors.New("digesting manifest")
-		}
-		imageDigest = d
+// imageIDForPulledImage makes a best-effort guess at an image ID for
+// a just-pulled image written to destName, where the pull returned manifestBytes
+func (r *Runtime) imageIDForPulledImage(destName reference.Named, manifestBytes []byte) (string, error) {
+	// The caller, copySingleImageFromRegistry, never triggers a multi-platform copy, so manifestBytes
+	// is always a single-platform manifest instance.
+	manifestDigest, err := manifest.Digest(manifestBytes)
+	if err != nil {
+		return "", err
 	}
-	images, err := r.store.ImagesByDigest(imageDigest)
+	destDigestedName, err := reference.WithDigest(reference.TrimNamed(destName), manifestDigest)
 	if err != nil {
-		return "", fmt.Errorf("listing images by manifest digest: %w", err)
+		return "", err
 	}
-
-	// If you have additionStores defined and the same image stored in
-	// both storage and additional store, it can be output twice.
-	//
-	// Worse, with zstd:chunked partial pulls, the same image can have several
+	storeRef, err := storageTransport.Transport.NewStoreReference(r.store, destDigestedName, "")
+	if err != nil {
+		return "", err
+	}
+	// With zstd:chunked partial pulls, the same image can have several
 	// different IDs, depending on which layers of the image were pulled using the
 	// partial pull (are identified by TOC, not by uncompressed digest).
 	//
 	// At this point, from just the manifest digest, we can’t tell which image
 	// is the one that was actually pulled. (They should all have the same contents
 	// unless the image author is malicious.)
-	// So just return the first matching image ID.
-	if len(images) == 0 {
-		return "", fmt.Errorf("identifying new image by manifest digest: %w", storage.ErrImageUnknown)
+	//
+	// FIXME: To return an accurate value, c/image would need to return the image ID,
+	// not just manifestBytes.
+	_, image, err := storageTransport.ResolveReference(storeRef)
+	if err != nil {
+		return "", fmt.Errorf("looking up a just-pulled image: %w", err)
 	}
-	return images[0].ID, nil
+	return image.ID, nil
 }
 
 // copySingleImageFromRegistry pulls the specified, possibly unqualified, name
@@ -702,7 +687,7 @@ func (r *Runtime) copySingleImageFromRegistry(ctx context.Context, imageName str
 		}
 
 		logrus.Debugf("Pulled candidate %s successfully", candidateString)
-		ids, err := r.imageIDForManifest(manifestBytes, sys)
+		ids, err := r.imageIDForPulledImage(candidate.Value, manifestBytes)
 		if err != nil {
 			return "", err
 		}