1 files changed, 44 insertions, 0 deletions
diff --git a/refs.c b/refs.c
index 1620a53c48..ad883ec4d9 100644
--- a/refs.c
+++ b/refs.c
@@ -1029,3 +1029,47 @@ int ref_is_hidden(const char *refname)
 	}
 	return 0;
 }
+
+const char *find_descendant_ref(const char *dirname,
+				const struct string_list *extras,
+				const struct string_list *skip)
+{
+	int pos;
+
+	if (!extras)
+		return NULL;
+
+	/*
+	 * Look at the place where dirname would be inserted into
+	 * extras. If there is an entry at that position that starts
+	 * with dirname (remember, dirname includes the trailing
+	 * slash) and is not in skip, then we have a conflict.
+	 */
+	for (pos = string_list_find_insert_index(extras, dirname, 0);
+	     pos < extras->nr; pos++) {
+		const char *extra_refname = extras->items[pos].string;
+
+		if (!starts_with(extra_refname, dirname))
+			break;
+
+		if (!skip || !string_list_has_string(skip, extra_refname))
+			return extra_refname;
+	}
+	return NULL;
+}
+
+int rename_ref_available(const char *oldname, const char *newname)
+{
+	struct string_list skip = STRING_LIST_INIT_NODUP;
+	struct strbuf err = STRBUF_INIT;
+	int ret;
+
+	string_list_insert(&skip, oldname);
+	ret = !verify_refname_available(newname, NULL, &skip, &err);
+	if (!ret)
+		error("%s", err.buf);
+
+	string_list_clear(&skip, 0);
+	strbuf_release(&err);
+	return ret;
+}