WIP support multiple different images

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

docker/internal/tarfile/writer.go

@@ -143,24 +143,51 @@ func (w *Writer) addLegacyTags(lastLayerID string, repoTags []reference.NamedTag
 	}
 }
 
+// checkManifestItemsMatch checks that a and b describe the same image,
+// and returns an error if that’s not the case (which should never happen).
+func checkManifestItemsMatch(a, b *ManifestItem) error {
+	if a.Config != b.Config {
+		return fmt.Errorf("Internal error: Trying to reuse ManifestItem values with configs %#v vs. %#v", a.Config, b.Config)
+	}
+	if len(a.Layers) != len(b.Layers) {
+		return fmt.Errorf("Internal error: Trying to reuse ManifestItem values with layers %#v vs. %#v", a.Layers, b.Layers)
+	}
+	for i := range a.Layers {
+		if a.Layers[i] != b.Layers[i] {
+			return fmt.Errorf("Internal error: Trying to reuse ManifestItem values with layers[i] %#v vs. %#v", a.Layers[i], b.Layers[i])
+		}
+	}
+	// Ignore RepoTags, that will be built later.
+	// Ignore Parent and LayerSources, which we don’t set to anything meaningful.
+	return nil
+}
+
 // addManifestTags records that repoTags point to (configPath, layerPaths)
 func (w *Writer) addManifestTags(configPath string, layerPaths []string, repoTags []reference.NamedTagged) error {
 	var item *ManifestItem
+	newItem := ManifestItem{
+		Config:       configPath,
+		RepoTags:     []string{},
+		Layers:       layerPaths,
+		Parent:       "", // We don’t have this information
+		LayerSources: nil,
+	}
 	if i, ok := w.manifestByConfig[configPath]; ok {
-		// FIXME: compare Layers array
 		item = &w.manifest[i]
+		if err := checkManifestItemsMatch(item, &newItem); err != nil {
+			return err
+		}
 	} else {
 		i := len(w.manifest)
-		w.manifest = append(w.manifest, ManifestItem{
-			Config:       configPath,
-			RepoTags:     []string{},
-			Layers:       layerPaths,
-			Parent:       "",
-			LayerSources: nil,
-		})
+		w.manifestByConfig[configPath] = i
+		w.manifest = append(w.manifest, newItem)
 		item = &w.manifest[i]
 	}
 
+	knownRepoTags := map[string]struct{}{}
+	for _, repoTag := range item.RepoTags {
+		knownRepoTags[repoTag] = struct{}{}
+	}
 	for _, tag := range repoTags {
 		// For github.com/docker/docker consumers, this works just as well as
 		//   refString := ref.String()
@@ -179,8 +206,11 @@ func (w *Writer) addManifestTags(configPath string, layerPaths []string, repoTag
 		// See https://github.com/containers/image/issues/72 for a more detailed
 		// analysis and explanation.
 		refString := fmt.Sprintf("%s:%s", tag.Name(), tag.Tag())
-		// FIXME: Only if it does not already exist?
-		item.RepoTags = append(item.RepoTags, refString)
+
+		if _, ok := knownRepoTags[refString]; !ok {
+			item.RepoTags = append(item.RepoTags, refString)
+			knownRepoTags[refString] = struct{}{}
+		}
 	}
 
 	return nil