LVLb
cur_state == LVLb || cur_state == LVLc)
(void) sigaddset(&act.sa_mask, LVLb);
(void) sigaction(LVLb, &act, NULL);
{ LVLb, MASKb, 'b', 0 },
cur_state != LVLb && cur_state != LVLc)
} else if (cur_state == LVLa || cur_state == LVLb ||
new_state == LVLb ||