libimage: preserve optional name when pulling from OCI transport

When pulling from an OCI source, make sure to preseve the optional name.
For instance, a `podman pull oci:/tmp/foo:quay.io/foo/bar:latest` should
pull the image and name it `quay.io/foo/bar:latest`.

While at it, also fix a bug when pulling an OCI without the optional
name.  Previously, we used the path to name the image which will error
in most cases due to invalid characters (e.g., capital ones).  Hence,
apply the same trick as for the `dir` transport and generate a sha.

Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

common/libimage/pull.go

@@ -230,8 +230,18 @@ func (r *Runtime) copyFromDefault(ctx context.Context, ref types.ImageReference,
 
 	case ociTransport.Transport.Name():
 		split := strings.SplitN(ref.StringWithinTransport(), ":", 2)
-		storageName = toLocalImageName(split[0])
-		imageName = storageName
+		if len(split) == 1 || split[1] == "" {
+			// Same trick as for the dir transport: we cannot use
+			// the path to a directory as the name.
+			storageName, err = getImageID(ctx, ref, nil)
+			if err != nil {
+				return nil, err
+			}
+			imageName = "sha256:" + storageName[1:]
+		} else { // If the OCI-reference includes an image reference, use it
+			storageName = split[1]
+			imageName = storageName
+		}
 
 	case ociArchiveTransport.Transport.Name():
 		manifestDescriptor, err := ociArchiveTransport.LoadManifestDescriptorWithContext(r.SystemContext(), ref)

common/libimage/pull_test.go

@@ -220,3 +220,52 @@ func TestShortNameAndIDconflict(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, busybox[0].ID(), img.ID())
 }
+
+func TestPullOCINoReference(t *testing.T) {
+	// Exercise pulling from the OCI transport and make sure that a
+	// specified reference is preserved in the image name.
+
+	busybox := "docker.io/library/busybox:latest"
+	runtime, cleanup := testNewRuntime(t)
+	defer cleanup()
+	ctx := context.Background()
+	pullOptions := &PullOptions{}
+	pullOptions.Writer = os.Stdout
+
+	images, err := runtime.Pull(ctx, busybox, config.PullPolicyAlways, pullOptions)
+	require.NoError(t, err)
+	require.Len(t, images, 1)
+
+	// Push one image without the optional reference
+	ociPathNoRef := "oci:" + t.TempDir() + "noRef"
+	_, err = runtime.Push(ctx, busybox, ociPathNoRef, nil)
+	require.NoError(t, err)
+
+	// Push another image _with_ the optional reference which allows for
+	// preserving the name.
+	ociPathWithRef := "oci:" + t.TempDir() + "withRef:" + busybox
+	_, err = runtime.Push(ctx, busybox, ociPathWithRef, nil)
+	require.NoError(t, err)
+
+	_, errors := runtime.RemoveImages(ctx, []string{busybox}, nil)
+	require.Nil(t, errors)
+
+	images, err = runtime.Pull(ctx, ociPathNoRef, config.PullPolicyAlways, pullOptions)
+	require.NoError(t, err)
+	require.Len(t, images, 1)
+
+	exists, err := runtime.Exists(busybox) // busybox does not exist
+	require.NoError(t, err)
+	require.False(t, exists)
+
+	names := images[0].Names() // The image has no names (i.e., <none>)
+	require.Nil(t, names)
+
+	images, err = runtime.Pull(ctx, ociPathWithRef, config.PullPolicyAlways, pullOptions)
+	require.NoError(t, err)
+	require.Len(t, images, 1)
+
+	exists, err = runtime.Exists(busybox) // busybox does exist now
+	require.NoError(t, err)
+	require.True(t, exists)
+}