rctl_walk
if (rctl_walk(store_rctls, Pr) != 0)
(void) rctl_walk(rctl_save_walk_cb, fp);
(void) rctl_walk(rctl_walk_cb, NULL);
int rctl_walk(int (*)(const char *, void *), void *);
if (rctl_walk(rctlwalkfunc, (void *)kv_array->data[i].key)
return (rctl_walk(rctl_check, (void *)name) == 1);