-gint collection_add(CollectionData *cd, FileData *fd, gint sorted);
-gint collection_add_check(CollectionData *cd, FileData *fd, gint sorted, gint must_exist);
-gint collection_insert(CollectionData *cd, FileData *fd, CollectInfo *insert_ci, gint sorted);
-gint collection_remove(CollectionData *cd, FileData *fd);
+gboolean collection_add(CollectionData *cd, FileData *fd, gboolean sorted);
+gboolean collection_add_check(CollectionData *cd, FileData *fd, gboolean sorted, gboolean must_exist);
+gboolean collection_insert(CollectionData *cd, FileData *fd, CollectInfo *insert_ci, gboolean sorted);
+gboolean collection_remove(CollectionData *cd, FileData *fd);