ubi_get_num_by_path
err = ubi_get_num_by_path(name, &cur_ubi_num, &cur_vol_id);
error = ubi_get_num_by_path(pathname, &ubi_num, &vol_id);
int ubi_get_num_by_path(const char *pathname, int *ubi_num, int *vol_id);