LVLc
cur_state == LVLb || cur_state == LVLc)
(void) sigaddset(&act.sa_mask, LVLc);
(void) sigaction(LVLc, &act, NULL);
{ LVLc, MASKc, 'c', 0 }
cur_state != LVLb && cur_state != LVLc)
cur_state == LVLc) {
new_state == LVLc) {