tty.c

早期freebsd实现

		 * Give user character.
		 */
 		error = ureadc(c, uio);
		if (error)
			break;
 		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;
	}
	/*
	 * Look to unblock output now that (presumably)
	 * the input queue has gone down.
	 */
	s = spltty();
	if (ISSET(tp->t_state, TS_TBLOCK) && tp->t_rawq.c_cc < TTYHOG/5) {
		if (cc[VSTART] != _POSIX_VDISABLE &&
		    putc(cc[VSTART], &tp->t_outq) == 0) {
			CLR(tp->t_state, TS_TBLOCK);
			ttstart(tp);
		}
	}
	splx(s);
	return (error);
}

/*
 * 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 + 200)
		while (tp->t_outq.c_cc > hiwat) {
			ttstart(tp);
			if (wait == 0 || curproc->p_siglist != oldsig) {
				splx(s);
				return (0);
			}
			timeout((void (*)__P((void *)))wakeup,
			    (void *)&tp->t_outq, hz);
			SET(tp->t_state, TS_ASLEEP);
			sleep((caddr_t)&tp->t_outq, PZERO - 1);
		}
	splx(s);
	return (1);
}

/*
 * 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;
	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_CARR_ON) &&
	    !ISSET(tp->t_cflag, CLOCAL)) {
		if (ISSET(tp->t_state, TS_ISOPEN)) {
			splx(s);
			return (EIO);
		} else if (flag & IO_NDELAY) {
			splx(s);
			error = EWOULDBLOCK;
			goto out;
		} else {
			/* Sleep awaiting carrier. */
			error = ttysleep(tp,
			    &tp->t_rawq, TTIPRI | PCATCH,ttopen, 0);
			splx(s);
			if (error)
				goto out;
			goto loop;
		}
	}
	splx(s);
	/*
	 * Hang the process if it's in the background.
	 */
	p = curproc;
	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);
		if (error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, ttybg, 0))
			goto out;
		goto loop;
	}
	/*
	 * 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 = min(uio->uio_resid, OBUFSIZ);
			cp = obuf;
			error = uiomove(cp, cc, uio);
			if (error) {
				cc = 0;
				break;
			}
		}
		/*
		 * If nothing fancy need be done, grab those characters we
		 * can handle without any of ttyoutput's processing and
		 * just transfer them to the output q.  For those chars
		 * which require special processing (as indicated by the
		 * bits in char_type), call ttyoutput.  After processing
		 * a hunk of data, look for FLUSHO so ^O's will take effect
		 * immediately.
		 */
		while (cc > 0) {
			if (!ISSET(tp->t_oflag, OPOST))
				ce = cc;
			else {
				ce = cc - scanc((u_int)cc, (u_char *)cp,
				   (u_char *)char_type, CCLASSMASK);
				/*
				 * If ce is zero, then we're processing
				 * a special character through ttyoutput.
				 */
				if (ce == 0) {
					tp->t_rocount = 0;
					if (ttyoutput(*cp, tp) >= 0) {
						/* No Clists, wait a bit. */
						ttstart(tp);
						if (error = ttysleep(tp, &lbolt,
						    TTOPRI | PCATCH, ttybuf, 0))
							break;
						goto loop;
					}
					cp++;
					cc--;
					if (ISSET(tp->t_lflag, FLUSHO) ||
					    tp->t_outq.c_cc > hiwat)
						goto ovhiwat;
					continue;
				}
			}
			/*
			 * A bunch of normal characters have been found.
			 * Transfer them en masse to the output queue and
			 * continue processing at the top of the loop.
			 * If there are any further characters in this
			 * <= OBUFSIZ chunk, the first should be a character
			 * requiring special handling by ttyoutput.
			 */
			tp->t_rocount = 0;
			i = b_to_q(cp, ce, &tp->t_outq);
			ce -= i;
			tp->t_column += ce;
			cp += ce, cc -= ce, tk_nout += ce;
			tp->t_outcc += ce;
			if (i > 0) {
				/* No Clists, wait a bit. */
				ttstart(tp);
				if (error = ttysleep(tp,
				    &lbolt, TTOPRI | PCATCH, ttybuf, 0))
					break;
				goto loop;
			}
			if (ISSET(tp->t_lflag, FLUSHO) ||
			    tp->t_outq.c_cc > hiwat)
				break;
		}
		ttstart(tp);
	}
out:
	/*
	 * If cc is nonzero, we leave the uio structure inconsistent, as the
	 * offset and iov pointers have moved forward, but it doesn't matter
	 * (the call will either return short or restart with a new uio).
	 */
	uio->uio_resid += cc;
	return (error);

ovhiwat:
	ttstart(tp);
	s = spltty();
	/*
	 * This can only occur if FLUSHO is set in t_lflag,
	 * or if ttstart/oproc is synchronous (or very fast).
	 */
	if (tp->t_outq.c_cc <= hiwat) {
		splx(s);
		goto loop;
	}
	if (flag & IO_NDELAY) {
		splx(s);
		uio->uio_resid += cc;
		return (uio->uio_resid == cnt ? EWOULDBLOCK : 0);
	}
	SET(tp->t_state, TS_ASLEEP);
	error = ttysleep(tp, &tp->t_outq, TTOPRI | PCATCH, ttyout, 0);
	splx(s);
	if (error)
		goto out;
	goto loop;
}

/*
 * Rubout one character from the rawq of tp
 * as cleanly as possible.
 */
void
ttyrub(c, tp)
	register int c;
	register struct tty *tp;
{
	register char *cp;
	register int savecol;
	int tabc, s;

	if (!ISSET(tp->t_lflag, ECHO) || ISSET(tp->t_lflag, EXTPROC))
		return;
	CLR(tp->t_lflag, FLUSHO);
	if (ISSET(tp->t_lflag, ECHOE)) {
		if (tp->t_rocount == 0) {
			/*
			 * Screwed by ttwrite; retype
			 */
			ttyretype(tp);
			return;
		}
		if (c == ('\t' | TTY_QUOTE) || c == ('\n' | TTY_QUOTE))
			ttyrubo(tp, 2);
		else {
			CLR(c, ~TTY_CHARMASK);
			switch (CCLASS(c)) {
			case ORDINARY:
				ttyrubo(tp, 1);
				break;
			case BACKSPACE:
			case CONTROL:
			case NEWLINE:
			case RETURN:
			case VTAB:
				if (ISSET(tp->t_lflag, ECHOCTL))
					ttyrubo(tp, 2);
				break;
			case TAB:
				if (tp->t_rocount < tp->t_rawq.c_cc) {
					ttyretype(tp);
					return;
				}
				s = spltty();
				savecol = tp->t_column;
				SET(tp->t_state, TS_CNTTB);
				SET(tp->t_lflag, FLUSHO);
				tp->t_column = tp->t_rocol;
				cp = tp->t_rawq.c_cf;
				if (cp)
					tabc = *cp;	/* XXX FIX NEXTC */
				for (; cp; cp = nextc(&tp->t_rawq, cp, &tabc))
					ttyecho(tabc, tp);
				CLR(tp->t_lflag, FLUSHO);
				CLR(tp->t_state, TS_CNTTB);
				splx(s);

				/* savecol will now be length of the tab. */
				savecol -= tp->t_column;
				tp->t_column += savecol;
				if (savecol > 8)
					savecol = 8;	/* overflow screw */
				while (--savecol >= 0)
					(void)ttyoutput('\b', tp);
				break;
			default:			/* XXX */
#define	PANICSTR	"ttyrub: would panic c = %d, val = %d\n"
				(void)printf(PANICSTR, c, CCLASS(c));
#ifdef notdef
				panic(PANICSTR, c, CCLASS(c));
#endif
			}
		}
	} else if (ISSET(tp->t_lflag, ECHOPRT)) {
		if (!ISSET(tp->t_state, TS_ERASE)) {
			SET(tp->t_state, TS_ERASE);
			(void)ttyoutput('\\', tp);
		}
		ttyecho(c, tp);
	} else
		ttyecho(tp->t_cc[VERASE], tp);
	--tp->t_rocount;
}

/*
 * Back over cnt characters, erasing them.
 */
static void
ttyrubo(tp, cnt)
	register struct tty *tp;
	int cnt;
{

	while (cnt-- > 0) {
		(void)ttyoutput('\b', tp);
		(void)ttyoutput(' ', tp);
		(void)ttyoutput('\b', tp);
	}
}

/*
 * ttyretype --
 *	Reprint the rawq line.  Note, it is assumed that c_cc has already
 *	been checked.
 */
void
ttyretype(tp)
	register struct tty *tp;
{
	register char *cp;
	int s, c;

	/* Echo the reprint character. */
	if (tp->t_cc[VREPRINT] != _POSIX_VDISABLE)
		ttyecho(tp->t_cc[VREPRINT], tp);

	(void)ttyoutput('\n', tp);

	/*
	 * XXX
	 * FIX: NEXTC IS BROKEN - DOESN'T CHECK QUOTE
	 * BIT OF FIRST CHAR.
	 */
	s = spltty();
	for (cp = tp->t_canq.c_cf, c = (cp != NULL ? *cp : 0);
	    cp != NULL; cp = nextc(&tp->t_canq, cp, &c))
		ttyecho(c, tp);
	for (cp = tp->t_rawq.c_cf, c = (cp != NULL ? *cp : 0);
	    cp != NULL; cp = nextc(&tp->t_rawq, cp, &c))
		ttyecho(c, tp);
	CLR(tp->t_state, TS_ERASE);
	splx(s);

	tp->t_rocount = tp->t_rawq.c_cc;
	tp->t_rocol = 0;
}

/*
 * Echo a typed character to the terminal.
 */
static void
ttyecho(c, tp)
	register int c;
	register struct tty *tp;
{

	if (!ISSET(tp->t_state, TS_CNTTB))
		CLR(tp->t_lflag, FLUSHO);
	if ((!ISSET(tp->t_lflag, ECHO) &&
	    (!ISSET(tp->t_lflag, ECHONL) || c == '\n')) ||
	    ISSET(tp->t_lflag, EXTPROC))
		return;
	if (ISSET(tp->t_lflag, ECHOCTL) &&
	    (ISSET(c, TTY_CHARMASK) <= 037 && c != '\t' && c != '\n' ||
	    ISSET(c, TTY_CHARMASK) == 0177)) {
		(void)ttyoutput('^', tp);
		CLR(c, ~TTY_CHARMASK);
		if (c == 0177)
			c = '?';
		else
			c += 'A' - 1;
	}
	(void)ttyoutput(c, tp);
}

/*
 * Wake up any readers on a tty.
 */
void
ttwakeup(tp)
	register struct tty *tp;
{

	selwakeup(&tp->t_rsel);
	if (ISSET(tp->t_state, TS_ASYNC))
		pgsignal(tp->t_pgrp, SIGIO, 1);
	wakeup((caddr_t)&tp->t_rawq);
}

/*
 * Look up a code for a specified speed in a conversion table;
 * used by drivers to map software speed values to hardware parameters.
 */
int
ttspeedtab(speed, table)
	int speed;
	register struct speedtab *table;
{

	for ( ; table->sp_speed != -1; table++)
		if (table->sp_speed == speed)
			return (table->sp_code);
	return (-1);
}

/*
 * Set tty hi and low water marks.
 *
 * Try to arrange the dynamics so there's about one second
 * from hi to low water.
 *
 */
void
ttsetwater(tp)
	struct tty *tp;
{
	register int cps, x;

#define CLAMP(x, h, l)	((x) > h ? h : ((x) < l) ? l : (x))

	cps = tp->t_ospeed / 10;
	tp->t_lowat = x = CLAMP(cps / 2, TTMAXLOWAT, TTMINLOWAT);
	x += cps;
	x = CLAMP(x, TTMAXHIWAT, TTMINHIWAT);
	tp->t_hiwat = roundup(x, CBSIZE);
#undef	CLAMP
}

/*
 * Report on state of foreground process group.
 */
void
ttyinfo(tp)
	register struct tty *tp;
{
	register struct proc *p, *pick;
	struct timeval utime, stime;
	int tmp;

	if (ttycheckoutq(tp,0) == 0)
		return;

	/* Print load average. */
	tmp = (averunnable.ldavg[0] * 100 + FSCALE / 2) >> FSHIFT;
	ttyprintf(tp, "load: %d.%02d ", tmp / 100, tmp % 100);

	if (tp->t_session == NULL)
		ttyprintf(tp, "not a controlling terminal\n");
	else if (tp->t_pgrp == NULL)
		ttyprintf(tp, "no foreground process group\n");
	else if ((p = tp->t_pgrp->pg_mem) == NULL)
		ttyprintf(tp, "empty foreground process group\n");
	else {
		/* Pick interesting process. */
		for (pick = NULL; p != NULL; p = p->p_pgrpnxt)
			if (proc_compare(pick, p))
				pick = p;

		ttyprintf(tp, " cmd: %s %d [%s] ", pick->p_comm, pick->p_pid,
		    pick->p_stat == SRUN ? "running" :
		    pick->p_wmesg ? pick->p_wmesg : "iowait");

		calcru(pick, &utime, &stime, NULL);

		/* Print user time. */
		ttyprintf(tp, "%d.%02du ",
		    utime.tv_sec, (utime.tv_usec + 5000) / 10000);

		/* Print system time. */
		ttyprintf(tp, "%d.%02ds ",
		    stime.tv_sec, (stime.tv_usec + 5000) / 10000);

#define	pgtok(a)	(((a) * NBPG) / 1024)
		/* Print percentage cpu, resident set size. */
		tmp = pick->p_pctcpu * 10000 + FSCALE / 2 >> FSHIFT;
		ttyprintf(tp, "%d%% %dk\n",
		    tmp / 100,
		    pick->p_stat == SIDL || pick->p_stat == SZOMB ? 0 :
#ifdef pmap_resident_count
			pgtok(pmap_resident_count(&pick->p_vmspace->vm_pmap))
#else
			pgtok(pick->p_vmspace->vm_rssize)
#endif
			);
	}
	tp->t_rocount = 0;	/* so pending input will be retyped if BS */
}

/*
 * Returns 1 if p2 is "better" than p1
 *
 * The algorithm for picking the "interesting" process is thus:
 *
 *	1) Only foreground processes are eligible - implied.
 *	2) Runnable processes are favored over anything else.  The runner
 *	   with the highest cpu utilization is picked (p_estcpu).  Ties are
 *	   broken by picking the highest pid.
 *	3) The sleeper with the shortest sleep time is next.  With ties,
 *	   we pick out just "short-term" sleepers (P_SINTR == 0).
 *	4) Further ties are broken by picking the highest pid.
 */
#define ISRUN(p)	(((p)->p_stat == SRUN) || ((p)->p_stat == SIDL))
#define TESTAB(a, b)    ((a)<<1 | (b))
#define ONLYA   2
#define ONLYB   1
#define BOTH    3

static int
proc_compare(p1, p2)
	register struct proc *p1, *p2;
{

	if (p1 == NULL)
		return (1);
	/*
	 * see if at least one of them is runnable
	 */
	switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
	case ONLYA:
		return (0);
	case ONLYB:
		return (1);
	case BOTH:
		/*
		 * tie - favor one with highest recent cpu utilization
		 */
		if (p2->p_estcpu > p1->p_estcpu)
			return (1);
		if (p1->p_estcpu > p2->p_estcpu)
			return (0);
		return (p2->p_pid > p1->p_pid);	/* tie - return highest pid */
	}
	/*
 	 * weed out zombies
	 */
	switch (TESTAB(p1->p_stat == SZOMB, p2->p_stat == SZOMB)) {
	case ONLYA:
		return (1);
	case ONLYB:
		return (0);
	case BOTH:
		return (p2->p_pid > p1->p_pid); /* tie - return highest pid */
	}
	/*
	 * pick the one with the smallest sleep time
	 */
	if (p2->p_slptime > p1->p_slptime)
		return (0);
	if (p1->p_slptime > p2->p_slptime)
		return (1);
	/*
	 * favor one sleeping in a non-interruptible sleep
	 */
	if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
		return (1);
	if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
		return (0);
	return (p2->p_pid > p1->p_pid);		/* tie - return highest pid */
}

/*
 * Output char to tty; console putchar style.
 */
int
tputchar(c, tp)
	int c;
	struct tty *tp;
{
	register int s;

	s = spltty();
	if (ISSET(tp->t_state,
	    TS_CARR_ON | TS_ISOPEN) != (TS_CARR_ON | TS_ISOPEN)) {
		splx(s);
		return (-1);
	}
	if (c == '\n')
		(void)ttyoutput('\r', tp);
	(void)ttyoutput(c, tp);
	ttstart(tp);
	splx(s);
	return (0);
}

/*
 * Sleep on chan, returning ERESTART if tty changed while we napped and
 * returning any errors (e.g. EINTR/ETIMEDOUT) reported by tsleep.  If
 * the tty is revoked, restarting a pending call will redo validation done
 * at the start of the call.
 */
int
ttysleep(tp, chan, pri, wmesg, timo)
	struct tty *tp;
	void *chan;
	int pri, timo;
	char *wmesg;
{
	int error;
	short gen;

	gen = tp->t_gen;
	if (error = tsleep(chan, pri, wmesg, timo))
		return (error);
	return (tp->t_gen == gen ? 0 : ERESTART);
}