+/*
+ * Register the specified ref_store to be the one that should be used
+ * for submodule (or the main repository if submodule is NULL). It is
+ * a fatal error to call this function twice for the same submodule.
+ */
+static void register_ref_store(struct ref_store *refs, const char *submodule)
+{
+ if (!submodule) {
+ if (main_ref_store)
+ die("BUG: main_ref_store initialized twice");
+
+ refs->next = NULL;
+ main_ref_store = refs;
+ } else {
+ if (lookup_ref_store(submodule))
+ die("BUG: ref_store for submodule '%s' initialized twice",
+ submodule);
+
+ refs->next = submodule_ref_stores;
+ submodule_ref_stores = refs;
+ }
+}
+