tty.c

来自「基于组件方式开发操作系统的OSKIT源代码」· C语言 代码 · 共 2,414 行 · 第 1/4 页

				 * the checks in ttywait() since the timeout
				 * will save us.
				 */
				SET(tp->t_state, TS_SO_OCOMPLETE);
				ttysleep(tp, TSA_OCOMPLETE(tp), TTOPRI,
					 "ttyfls", hz / 10);
				/*
				 * Don't try sending the stop character again.
				 */
				CLR(tp->t_state, TS_TBLOCK);
				goto again;
			}
#endif
		}
	}
	if (rw & FWRITE) {
		FLUSHQ(&tp->t_outq);
		ttwwakeup(tp);
	}
	splx(s);
}

/*
 * Copy in the default termios characters.
 */
void
termioschars(t)
	struct termios *t;
{

	bcopy(ttydefchars, t->c_cc, sizeof t->c_cc);
}

/*
 * Old interface.
 */
void
ttychars(tp)
	struct tty *tp;
{

	termioschars(&tp->t_termios);
}

/*
 * Handle input high water.  Send stop character for the IXOFF case.  Turn
 * on our input flow control bit and propagate the changes to the driver.
 * XXX the stop character should be put in a special high priority queue.
 */
void
ttyblock(tp)
	struct tty *tp;
{

	SET(tp->t_state, TS_TBLOCK);
	if (ISSET(tp->t_iflag, IXOFF) && tp->t_cc[VSTOP] != _POSIX_VDISABLE &&
	    putc(tp->t_cc[VSTOP], &tp->t_outq) != 0)
		CLR(tp->t_state, TS_TBLOCK);	/* try again later */
	ttstart(tp);
}

/*
 * Handle input low water.  Send start character for the IXOFF case.  Turn
 * off our input flow control bit and propagate the changes to the driver.
 * XXX the start character should be put in a special high priority queue.
 */
static void
ttyunblock(tp)
	struct tty *tp;
{

	CLR(tp->t_state, TS_TBLOCK);
	if (ISSET(tp->t_iflag, IXOFF) && tp->t_cc[VSTART] != _POSIX_VDISABLE &&
	    putc(tp->t_cc[VSTART], &tp->t_outq) != 0)
		SET(tp->t_state, TS_TBLOCK);	/* try again later */
	ttstart(tp);
}

void
ttrstrt(tp_arg)
	void *tp_arg;
{
	struct tty *tp;
	int s;

#ifdef DIAGNOSTIC
	if (tp_arg == NULL)
		panic("ttrstrt");
#endif
	tp = tp_arg;
	s = spltty();

	CLR(tp->t_state, TS_TIMEOUT);
	ttstart(tp);

	splx(s);
}

int
ttstart(tp)
	struct tty *tp;
{

	if (tp->t_oproc != NULL)	/* XXX: Kludge for pty. */
		(*tp->t_oproc)(tp);
	return (0);
}

/*
 * "close" a line discipline
 */
int
ttylclose(tp, flag)
	struct tty *tp;
	int flag;
{

	if (flag & FNONBLOCK || ttywflush(tp))
		ttyflush(tp, FREAD | FWRITE);
	return (0);
}

/*
 * Handle modem control transition on a tty.
 * Flag indicates new state of carrier.
 * Returns 0 if the line should be turned off, otherwise 1.
 */
int
ttymodem(tp, flag)
	register struct tty *tp;
	int flag;
{

	if (ISSET(tp->t_state, TS_CARR_ON) && ISSET(tp->t_cflag, MDMBUF)) {
		/*
		 * MDMBUF: do flow control according to carrier flag
		 * XXX TS_CAR_OFLOW doesn't do anything yet.  TS_TTSTOP
		 * works if IXON and IXANY are clear.
		 */
		if (flag) {
			CLR(tp->t_state, TS_CAR_OFLOW);
			CLR(tp->t_state, TS_TTSTOP);
			ttstart(tp);
		} else if (!ISSET(tp->t_state, TS_CAR_OFLOW)) {
			SET(tp->t_state, TS_CAR_OFLOW);
			SET(tp->t_state, TS_TTSTOP);
#ifdef sun4c						/* XXX */
			(*tp->t_stop)(tp, 0);
#else
			(*cdevsw[major(tp->t_dev)].d_stop)(tp, 0);
#endif
		}
	} else if (flag == 0) {
		/*
		 * Lost carrier.
		 */
		CLR(tp->t_state, TS_CARR_ON);
		if (ISSET(tp->t_state, TS_ISOPEN) &&
		    !ISSET(tp->t_cflag, CLOCAL)) {
			SET(tp->t_state, TS_ZOMBIE);
			CLR(tp->t_state, TS_CONNECTED);
			if (tp->t_session && tp->t_session->s_leader)
				psignal(tp->t_session->s_leader, SIGHUP);
			ttyflush(tp, FREAD | FWRITE);
			return (0);
		}
	} else {
		/*
		 * Carrier now on.
		 */
		SET(tp->t_state, TS_CARR_ON);
		if (!ISSET(tp->t_state, TS_ZOMBIE))
			SET(tp->t_state, TS_CONNECTED);
		wakeup(TSA_CARR_ON(tp));
		ttwakeup(tp);
		ttwwakeup(tp);
	}
	return (1);
}

/*
 * Reinput pending characters after state switch
 * call at spltty().
 */
static void
ttypend(tp)
	register struct tty *tp;
{
	struct clist tq;
	register int c;

	CLR(tp->t_lflag, PENDIN);
	SET(tp->t_state, TS_TYPEN);
	/*
	 * XXX this assumes too much about clist internals.  It may even
	 * fail if the cblock slush pool is empty.  We can't allocate more
	 * cblocks here because we are called from an interrupt handler
	 * and clist_alloc_cblocks() can wait.
	 */
	tq = tp->t_rawq;
	bzero(&tp->t_rawq, sizeof tp->t_rawq);
	tp->t_rawq.c_cbmax = tq.c_cbmax;
	tp->t_rawq.c_cbreserved = tq.c_cbreserved;
	while ((c = getc(&tq)) >= 0)
		ttyinput(c, tp);
	CLR(tp->t_state, TS_TYPEN);
}

/*
 * Process a read call on a tty device.
 */
int
ttread(tp, uio, flag)
	register struct tty *tp;
	struct uio *uio;
	int flag;
{
	register struct clist *qp;
	register int c;
	register tcflag_t lflag;
	register cc_t *cc = tp->t_cc;
	register struct proc *p = curproc;
	int s, first, error = 0;
	int has_stime = 0, last_cc = 0;
	long slp = 0;		/* XXX this should be renamed `timo'. */

loop:
	s = spltty();
	lflag = tp->t_lflag;
	/*
	 * take pending input first
	 */
	if (ISSET(lflag, PENDIN)) {
		ttypend(tp);
		splx(s);	/* reduce latency */
		s = spltty();
		lflag = tp->t_lflag;	/* XXX ttypend() clobbers it */
	}

#ifndef OSKIT
	/*
	 * Hang process if it's in the background.
	 */
	if (isbackground(p, tp)) {
		splx(s);
		if ((p->p_sigignore & sigmask(SIGTTIN)) ||
		   (p->p_sigmask & sigmask(SIGTTIN)) ||
		    p->p_flag & P_PPWAIT || p->p_pgrp->pg_jobc == 0)
			return (EIO);
		pgsignal(p->p_pgrp, SIGTTIN, 1);
		error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, "ttybg2", 0);
		if (error)
			return (error);
		goto loop;
	}
#endif /* !OSKIT */

	if (ISSET(tp->t_state, TS_ZOMBIE)) {
		splx(s);
		return (0);	/* EOF */
	}

	/*
	 * If canonical, use the canonical queue,
	 * else use the raw queue.
	 *
	 * (should get rid of clists...)
	 */
	qp = ISSET(lflag, ICANON) ? &tp->t_canq : &tp->t_rawq;

	if (flag & IO_NDELAY) {
		if (qp->c_cc > 0)
			goto read;
		if (!ISSET(lflag, ICANON) && cc[VMIN] == 0) {
			splx(s);
			return (0);
		}
		splx(s);
		return (EWOULDBLOCK);
	}
	if (!ISSET(lflag, ICANON)) {
		int m = cc[VMIN];
		long t = cc[VTIME];
		struct timeval stime, timecopy;
		int x;

		/*
		 * Check each of the four combinations.
		 * (m > 0 && t == 0) is the normal read case.
		 * It should be fairly efficient, so we check that and its
		 * companion case (m == 0 && t == 0) first.
		 * For the other two cases, we compute the target sleep time
		 * into slp.
		 */
		if (t == 0) {
			if (qp->c_cc < m)
				goto sleep;
			if (qp->c_cc > 0)
				goto read;

			/* m, t and qp->c_cc are all 0.  0 is enough input. */
			splx(s);
			return (0);
		}
		t *= 100000;		/* time in us */
#define diff(t1, t2) (((t1).tv_sec - (t2).tv_sec) * 1000000 + \
			 ((t1).tv_usec - (t2).tv_usec))
		if (m > 0) {
			if (qp->c_cc <= 0)
				goto sleep;
			if (qp->c_cc >= m)
				goto read;
			x = splclock();
			timecopy = time;
			splx(x);
			if (!has_stime) {
				/* first character, start timer */
				has_stime = 1;
				stime = timecopy;
				slp = t;
			} else if (qp->c_cc > last_cc) {
				/* got a character, restart timer */
				stime = timecopy;
				slp = t;
			} else {
				/* nothing, check expiration */
				slp = t - diff(timecopy, stime);
				if (slp <= 0)
					goto read;
			}
			last_cc = qp->c_cc;
		} else {	/* m == 0 */
			if (qp->c_cc > 0)
				goto read;
			x = splclock();
			timecopy = time;
			splx(x);
			if (!has_stime) {
				has_stime = 1;
				stime = timecopy;
				slp = t;
			} else {
				slp = t - diff(timecopy, stime);
				if (slp <= 0) {
					/* Timed out, but 0 is enough input. */
					splx(s);
					return (0);
				}
			}
		}
#undef diff
		/*
		 * Rounding down may make us wake up just short
		 * of the target, so we round up.
		 * The formula is ceiling(slp * hz/1000000).
		 * 32-bit arithmetic is enough for hz < 169.
		 * XXX see hzto() for how to avoid overflow if hz
		 * is large (divide by `tick' and/or arrange to
		 * use hzto() if hz is large).
		 */
		slp = (long) (((u_long)slp * hz) + 999999) / 1000000;
		goto sleep;
	}
	if (qp->c_cc <= 0) {
sleep:
		/*
		 * There is no input, or not enough input and we can block.
		 */
		error = ttysleep(tp, TSA_HUP_OR_INPUT(tp), TTIPRI | PCATCH,
				 ISSET(tp->t_state, TS_CONNECTED) ?
				 "ttyin" : "ttyhup", (int)slp);
		splx(s);
		if (error == EWOULDBLOCK)
			error = 0;
		else if (error)
			return (error);
		/*
		 * XXX what happens if another process eats some input
		 * while we are asleep (not just here)?  It would be
		 * safest to detect changes and reset our state variables
		 * (has_stime and last_cc).
		 */
		slp = 0;
		goto loop;
	}
read:
	splx(s);
	/*
	 * Input present, check for input mapping and processing.
	 */
	first = 1;
	if (ISSET(lflag, ICANON | ISIG))
		goto slowcase;
	for (;;) {
		char ibuf[IBUFSIZ];
		int icc;

		icc = imin(uio->uio_resid, IBUFSIZ);
		icc = q_to_b(qp, ibuf, icc);
		if (icc <= 0) {
			if (first)
				goto loop;
			break;
		}
		error = uiomove(ibuf, icc, uio);
		/*
		 * XXX if there was an error then we should ungetc() the
		 * unmoved chars and reduce icc here.
		 */
#if NSNP > 0
		if (ISSET(tp->t_lflag, ECHO) &&
		    ISSET(tp->t_state, TS_SNOOP) && tp->t_sc != NULL)
			snpin((struct snoop *)tp->t_sc, ibuf, icc);
#endif
		if (error)
			break;
 		if (uio->uio_resid == 0)
			break;
		first = 0;
	}
	goto out;
slowcase:
	for (;;) {
		c = getc(qp);
		if (c < 0) {
			if (first)
				goto loop;
			break;
		}
		/*
		 * delayed suspend (^Y)
		 */
		if (CCEQ(cc[VDSUSP], c) && ISSET(lflag, ISIG)) {
			pgsignal(tp->t_pgrp, SIGTSTP, 1);
			if (first) {
				error = ttysleep(tp, &lbolt, TTIPRI | PCATCH,
						 "ttybg3", 0);
				if (error)
					break;
				goto loop;
			}
			break;
		}
		/*
		 * Interpret EOF only in canonical mode.
		 */
		if (CCEQ(cc[VEOF], c) && ISSET(lflag, ICANON))
			break;
		/*
		 * Give user character.
		 */
 		error = ureadc(c, uio);
		if (error)
			/* XXX should ungetc(c, qp). */
			break;
#if NSNP > 0
		/*
		 * Only snoop directly on input in echo mode.  Non-echoed
		 * input will be snooped later iff the application echoes it.
		 */
		if (ISSET(tp->t_lflag, ECHO) &&
		    ISSET(tp->t_state, TS_SNOOP) && tp->t_sc != NULL)
			snpinc((struct snoop *)tp->t_sc, (char)c);
#endif
 		if (uio->uio_resid == 0)
			break;
		/*
		 * In canonical mode check for a "break character"
		 * marking the end of a "line of input".
		 */
		if (ISSET(lflag, ICANON) && TTBREAKC(c))
			break;
		first = 0;
	}

out:
	/*
	 * Look to unblock input now that (presumably)
	 * the input queue has gone down.
	 */
	s = spltty();
	if (ISSET(tp->t_state, TS_TBLOCK) &&
	    tp->t_rawq.c_cc + tp->t_canq.c_cc <= I_LOW_WATER)
		ttyunblock(tp);
	splx(s);

	return (error);
}

#ifndef OSKIT
/*
 * Check the output queue on tp for space for a kernel message (from uprintf
 * or tprintf).  Allow some space over the normal hiwater mark so we don't
 * lose messages due to normal flow control, but don't let the tty run amok.
 * Sleeps here are not interruptible, but we return prematurely if new signals
 * arrive.
 */
int
ttycheckoutq(tp, wait)
	register struct tty *tp;
	int wait;
{
	int hiwat, s, oldsig;

	hiwat = tp->t_hiwat;
	s = spltty();
	oldsig = wait ? curproc->p_siglist : 0;
	if (tp->t_outq.c_cc > hiwat + OBUFSIZ + 100)
		while (tp->t_outq.c_cc > hiwat) {
			ttstart(tp);
			if (tp->t_outq.c_cc <= hiwat)
				break;
			if (wait == 0 || curproc->p_siglist != oldsig) {
				splx(s);
				return (0);
			}
			SET(tp->t_state, TS_SO_OLOWAT);
			tsleep(TSA_OLOWAT(tp), PZERO - 1, "ttoutq", hz);
		}
	splx(s);
	return (1);
}
#endif /* !OSKIT */

/*
 * Process a write call on a tty device.
 */
int
ttwrite(tp, uio, flag)
	register struct tty *tp;
	register struct uio *uio;
	int flag;
{
	register char *cp = NULL;
	register int cc, ce;
	register struct proc *p;
	int i, hiwat, cnt, error, s;
	char obuf[OBUFSIZ];

	hiwat = tp->t_hiwat;
	cnt = uio->uio_resid;
	error = 0;
	cc = 0;
loop:
	s = spltty();
	if (ISSET(tp->t_state, TS_ZOMBIE)) {
		splx(s);
		if (uio->uio_resid == cnt)
			error = EIO;
		goto out;
	}
	if (!ISSET(tp->t_state, TS_CONNECTED)) {
		if (flag & IO_NDELAY) {
			splx(s);
			error = EWOULDBLOCK;
			goto out;
		}
		error = ttysleep(tp, TSA_CARR_ON(tp), TTIPRI | PCATCH,
				 "ttydcd", 0);
		splx(s);
		if (error)
			goto out;
		goto loop;
	}
	splx(s);
	/*
	 * Hang the process if it's in the background.
	 */
	p = curproc;
#ifndef OSKIT
	if (isbackground(p, tp) &&
	    ISSET(tp->t_lflag, TOSTOP) && (p->p_flag & P_PPWAIT) == 0 &&
	    (p->p_sigignore & sigmask(SIGTTOU)) == 0 &&
	    (p->p_sigmask & sigmask(SIGTTOU)) == 0 &&
	     p->p_pgrp->pg_jobc) {
		pgsignal(p->p_pgrp, SIGTTOU, 1);
		error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, "ttybg4", 0);
		if (error)
			goto out;
		goto loop;
	}
#endif /* !OSKIT */
	/*
	 * Process the user's data in at most OBUFSIZ chunks.  Perform any
	 * output translation.  Keep track of high water mark, sleep on
	 * overflow awaiting device aid in acquiring new space.
	 */
	while (uio->uio_resid > 0 || cc > 0) {
		if (ISSET(tp->t_lflag, FLUSHO)) {
			uio->uio_resid = 0;
			return (0);
		}
		if (tp->t_outq.c_cc > hiwat)
			goto ovhiwat;
		/*
		 * Grab a hunk of data from the user, unless we have some
		 * leftover from last time.
		 */
		if (cc == 0) {
			cc = imin(uio->uio_resid, OBUFSIZ);
			cp = obuf;
			error = uiomove(cp, cc, uio);
			if (error) {
				cc = 0;