fownsignal
fownsignal(pid, SIGIO, 0, 0, NULL);
fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
fownsignal(so->so_pgid, SIGURG, POLL_PRI, POLLPRI|POLLRDBAND, so);
fownsignal(so->so_pgid, SIGIO, code, band, so);
fownsignal(d->bd_pgid, SIGIO, 0, 0, NULL);
fownsignal(sc->sc_pgid, SIGIO, a, b, NULL);
fownsignal(tp->tun_pgid, SIGIO, POLL_HUP, 0, NULL);
fownsignal(tp->tun_pgid, SIGIO, POLL_IN, POLLIN|POLLRDNORM,
fownsignal(tp->tun_pgid, SIGIO, POLL_OUT, POLLOUT|POLLWRNORM,
void fownsignal(pid_t, int, int, int, void *);