Add Untag() to oci.Store.

Signed-off-by: Francis Laniel <[email protected]>

content/oci/oci.go

@@ -238,6 +238,38 @@ func (s *Store) Resolve(ctx context.Context, reference string) (ocispec.Descript
 	return desc, nil
 }
 
+func (s *Store) Untag(ctx context.Context, reference string) error {
+	s.sync.RLock()
+	defer s.sync.RUnlock()
+
+	if reference == "" {
+		return errdef.ErrMissingReference
+	}
+
+	// attempt resolving manifest
+	_, err := s.tagResolver.Resolve(ctx, reference)
+	if err != nil {
+		if errors.Is(err, errdef.ErrNotFound) {
+			// attempt resolving blob
+			_, err := resolveBlob(os.DirFS(s.root), reference)
+			if err != nil {
+				return err
+			}
+		}
+		return err
+	}
+
+	return s.untag(reference)
+}
+
+func (s *Store) untag(reference string) error {
+	s.tagResolver.Untag(reference)
+	if s.AutoSaveIndex {
+		return s.saveIndex()
+	}
+	return nil
+}
+
 // Predecessors returns the nodes directly pointing to the current node.
 // Predecessors returns nil without error if the node does not exists in the
 // store.