lib/repo: Add ostree_repo_traverse_commit_union_with_parents

This is a version of ostree_repo_traverse_commit_union that also
remembers where the objects came from, by recording the parent
relationships in a hashtable. This can be used to later find which
commits each object was from, which we want to use in fsck.

Closes: #1533
Approved by: cgwalters

src/libostree/ostree-repo.h

@@ -1112,6 +1112,12 @@ gboolean ostree_repo_static_delta_execute_offline (OstreeRepo
 _OSTREE_PUBLIC
 GHashTable *ostree_repo_traverse_new_reachable (void);
 
+_OSTREE_PUBLIC
+GHashTable *ostree_repo_traverse_new_parents (void);
+
+_OSTREE_PUBLIC
+char ** ostree_repo_traverse_parents_get_commits (GHashTable *parents, GVariant *object);
+
 _OSTREE_PUBLIC
 gboolean ostree_repo_traverse_commit (OstreeRepo         *repo,
                                       const char         *commit_checksum,
@@ -1127,6 +1133,14 @@ gboolean ostree_repo_traverse_commit_union (OstreeRepo         *repo,
                                             GHashTable         *inout_reachable,
                                             GCancellable       *cancellable,
                                             GError            **error);
+_OSTREE_PUBLIC
+gboolean ostree_repo_traverse_commit_union_with_parents (OstreeRepo         *repo,
+                                                         const char         *commit_checksum,
+                                                         int                 maxdepth,
+                                                         GHashTable         *inout_reachable,
+                                                         GHashTable         *inout_parents,
+                                                         GCancellable       *cancellable,
+                                                         GError            **error);
 
 struct _OstreeRepoCommitTraverseIter {
   gboolean initialized;