xref: /freebsd/sys/kern/tty_ttydisc.c (revision 2e3f49888ec8851bafb22011533217487764fdb0)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
5  * All rights reserved.
6  *
7  * Portions of this software were developed under sponsorship from Snow
8  * B.V., the Netherlands.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/param.h>
33 #include <sys/fcntl.h>
34 #include <sys/filio.h>
35 #include <sys/kernel.h>
36 #include <sys/signal.h>
37 #include <sys/sysctl.h>
38 #include <sys/systm.h>
39 #include <sys/tty.h>
40 #include <sys/ttycom.h>
41 #include <sys/ttydefaults.h>
42 #include <sys/uio.h>
43 #include <sys/vnode.h>
44 
45 #include <teken/teken.h>
46 #include <teken/teken_wcwidth.h>
47 
48 /*
49  * Standard TTYDISC `termios' line discipline.
50  */
51 
52 /* Statistics. */
53 static unsigned long tty_nin = 0;
54 SYSCTL_ULONG(_kern, OID_AUTO, tty_nin, CTLFLAG_RD,
55 	&tty_nin, 0, "Total amount of bytes received");
56 static unsigned long tty_nout = 0;
57 SYSCTL_ULONG(_kern, OID_AUTO, tty_nout, CTLFLAG_RD,
58 	&tty_nout, 0, "Total amount of bytes transmitted");
59 
60 /* termios comparison macro's. */
61 #define	CMP_CC(v,c) (tp->t_termios.c_cc[v] != _POSIX_VDISABLE && \
62 			tp->t_termios.c_cc[v] == (c))
63 #define	CMP_FLAG(field,opt) (tp->t_termios.c_ ## field ## flag & (opt))
64 
65 /* Characters that cannot be modified through c_cc. */
66 #define CTAB	'\t'
67 #define CNL	'\n'
68 #define CCR	'\r'
69 
70 /* Character is a control character. */
71 #define CTL_VALID(c)	((c) == 0x7f || (unsigned char)(c) < 0x20)
72 /* Control character should be processed on echo. */
73 #define CTL_ECHO(c,q)	(!(q) && ((c) == CERASE2 || (c) == CTAB || \
74     (c) == CNL || (c) == CCR))
75 /* Control character should be printed using ^X notation. */
76 #define CTL_PRINT(c,q)	((c) == 0x7f || ((unsigned char)(c) < 0x20 && \
77     ((q) || ((c) != CTAB && (c) != CNL))))
78 /* Character is whitespace. */
79 #define CTL_WHITE(c)	((c) == ' ' || (c) == CTAB)
80 /* Character is alphanumeric. */
81 #define CTL_ALNUM(c)	(((c) >= '0' && (c) <= '9') || \
82     ((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))
83 /* Character is UTF8-encoded. */
84 #define CTL_UTF8(c) (!!((c) & 0x80))
85 /* Character is a UTF8 continuation byte. */
86 #define CTL_UTF8_CONT(c) (((c) & 0xc0) == 0x80)
87 
88 #define	TTY_STACKBUF	256
89 #define UTF8_STACKBUF 4
90 
91 void
92 ttydisc_open(struct tty *tp)
93 {
94 	ttydisc_optimize(tp);
95 }
96 
97 void
98 ttydisc_close(struct tty *tp)
99 {
100 
101 	/* Clean up our flags when leaving the discipline. */
102 	tp->t_flags &= ~(TF_STOPPED|TF_HIWAT|TF_ZOMBIE);
103 	tp->t_termios.c_lflag &= ~FLUSHO;
104 
105 	/*
106 	 * POSIX states that we must drain output and flush input on
107 	 * last close.  Draining has already been done if possible.
108 	 */
109 	tty_flush(tp, FREAD | FWRITE);
110 
111 	if (ttyhook_hashook(tp, close))
112 		ttyhook_close(tp);
113 }
114 
115 /*
116  * Populate our break array; it should likely be at least 4 bytes in size to
117  * allow for \n, VEOF, and VEOL.
118  */
119 static void
120 ttydisc_read_break(struct tty *tp, char *breakc, size_t breaksz)
121 {
122 	size_t n = 0;
123 
124 	MPASS(breaksz != 0);
125 
126 	breakc[n++] = CNL;
127 #define BREAK_ADD(c) do { \
128 	MPASS(n < breaksz - 1);	/* NUL terminated */	\
129 	if (tp->t_termios.c_cc[c] != _POSIX_VDISABLE)	\
130 		breakc[n++] = tp->t_termios.c_cc[c];	\
131 } while (0)
132 	/* Determine which characters we should trigger on. */
133 	BREAK_ADD(VEOF);
134 	BREAK_ADD(VEOL);
135 #undef BREAK_ADD
136 
137 	breakc[n] = '\0';
138 }
139 
140 size_t
141 ttydisc_bytesavail(struct tty *tp)
142 {
143 	size_t clen;
144 	char breakc[4];
145 	unsigned char lastc = _POSIX_VDISABLE;
146 
147 	clen = ttyinq_bytescanonicalized(&tp->t_inq);
148 	if (!CMP_FLAG(l, ICANON) || clen == 0)
149 		return (clen);
150 
151 	ttydisc_read_break(tp, &breakc[0], sizeof(breakc));
152 	clen = ttyinq_findchar(&tp->t_inq, breakc, clen, &lastc);
153 
154 	/*
155 	 * We might have a partial line canonicalized in the input queue if we,
156 	 * for instance, switched to ICANON after taking some input in raw mode.
157 	 * In this case, read(2) will block because we only have a partial line.
158 	 */
159 	if (lastc == _POSIX_VDISABLE)
160 		return (0);
161 
162 	/* If VEOF was our terminal, it must be discarded (not counted). */
163 	if (CMP_CC(VEOF, lastc))
164 		clen--;
165 
166 	return (clen);
167 }
168 
169 void
170 ttydisc_canonicalize(struct tty *tp)
171 {
172 	char breakc[4];
173 
174 	/*
175 	 * If we're in non-canonical mode, it's as easy as just canonicalizing
176 	 * the current partial line.
177 	 */
178 	if (!CMP_FLAG(l, ICANON)) {
179 		ttyinq_canonicalize(&tp->t_inq);
180 		return;
181 	}
182 
183 	/*
184 	 * For canonical mode, we need to rescan the buffer for the last EOL
185 	 * indicator.
186 	 */
187 	ttydisc_read_break(tp, &breakc[0], sizeof(breakc));
188 	ttyinq_canonicalize_break(&tp->t_inq, breakc);
189 }
190 
191 static int
192 ttydisc_read_canonical(struct tty *tp, struct uio *uio, int ioflag)
193 {
194 	char breakc[4]; /* enough to hold \n, VEOF and VEOL. */
195 	int error;
196 	size_t clen, flen = 0;
197 	unsigned char lastc = _POSIX_VDISABLE;
198 
199 	ttydisc_read_break(tp, &breakc[0], sizeof(breakc));
200 
201 	do {
202 		error = tty_wait_background(tp, curthread, SIGTTIN);
203 		if (error)
204 			return (error);
205 
206 		/*
207 		 * Quite a tricky case: unlike the old TTY
208 		 * implementation, this implementation copies data back
209 		 * to userspace in large chunks. Unfortunately, we can't
210 		 * calculate the line length on beforehand if it crosses
211 		 * ttyinq_block boundaries, because multiple reads could
212 		 * then make this code read beyond the newline.
213 		 *
214 		 * This is why we limit the read to:
215 		 * - The size the user has requested
216 		 * - The blocksize (done in tty_inq.c)
217 		 * - The amount of bytes until the newline
218 		 *
219 		 * This causes the line length to be recalculated after
220 		 * each block has been copied to userspace. This will
221 		 * cause the TTY layer to return data in chunks using
222 		 * the blocksize (except the first and last blocks).
223 		 */
224 		clen = ttyinq_findchar(&tp->t_inq, breakc, uio->uio_resid + 1,
225 		    &lastc);
226 
227 		/* No more data. */
228 		if (clen == 0) {
229 			if (tp->t_flags & TF_ZOMBIE)
230 				return (0);
231 			else if (ioflag & IO_NDELAY)
232 				return (EWOULDBLOCK);
233 
234 			error = tty_wait(tp, &tp->t_inwait);
235 			if (error)
236 				return (error);
237 			continue;
238 		}
239 
240 		/*
241 		 * Don't send the EOF char back to userspace.  Our above call to
242 		 * ttyinq_findchar overreads by 1 character in case we would
243 		 * otherwise be leaving an EOF for the next read().  We'll trim
244 		 * clen back down to uio_resid whether we find our EOF or not.
245 		 */
246 		if (CMP_CC(VEOF, lastc))
247 			flen = 1;
248 
249 		/*
250 		 * Trim clen back down to the buffer size, since we had
251 		 * intentionally over-read.
252 		 */
253 		clen = MIN(uio->uio_resid + flen, clen);
254 		MPASS(flen <= clen);
255 
256 		/* Read and throw away the EOF character. */
257 		error = ttyinq_read_uio(&tp->t_inq, tp, uio, clen, flen);
258 		if (error)
259 			return (error);
260 
261 	} while (uio->uio_resid > 0 && lastc == _POSIX_VDISABLE);
262 
263 	return (0);
264 }
265 
266 static int
267 ttydisc_read_raw_no_timer(struct tty *tp, struct uio *uio, int ioflag)
268 {
269 	size_t vmin = tp->t_termios.c_cc[VMIN];
270 	ssize_t oresid = uio->uio_resid;
271 	int error;
272 
273 	MPASS(tp->t_termios.c_cc[VTIME] == 0);
274 
275 	/*
276 	 * This routine implements the easy cases of read()s while in
277 	 * non-canonical mode, namely case B and D, where we don't have
278 	 * any timers at all.
279 	 */
280 
281 	for (;;) {
282 		error = tty_wait_background(tp, curthread, SIGTTIN);
283 		if (error)
284 			return (error);
285 
286 		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
287 		    uio->uio_resid, 0);
288 		if (error)
289 			return (error);
290 		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
291 			return (0);
292 
293 		/* We have to wait for more. */
294 		if (tp->t_flags & TF_ZOMBIE)
295 			return (0);
296 		else if (ioflag & IO_NDELAY)
297 			return (EWOULDBLOCK);
298 
299 		error = tty_wait(tp, &tp->t_inwait);
300 		if (error)
301 			return (error);
302 	}
303 }
304 
305 static int
306 ttydisc_read_raw_read_timer(struct tty *tp, struct uio *uio, int ioflag,
307     int oresid)
308 {
309 	size_t vmin = MAX(tp->t_termios.c_cc[VMIN], 1);
310 	unsigned int vtime = tp->t_termios.c_cc[VTIME];
311 	struct timeval end, now, left;
312 	int error, hz;
313 
314 	MPASS(tp->t_termios.c_cc[VTIME] != 0);
315 
316 	/* Determine when the read should be expired. */
317 	end.tv_sec = vtime / 10;
318 	end.tv_usec = (vtime % 10) * 100000;
319 	getmicrotime(&now);
320 	timevaladd(&end, &now);
321 
322 	for (;;) {
323 		error = tty_wait_background(tp, curthread, SIGTTIN);
324 		if (error)
325 			return (error);
326 
327 		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
328 		    uio->uio_resid, 0);
329 		if (error)
330 			return (error);
331 		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
332 			return (0);
333 
334 		/* Calculate how long we should wait. */
335 		getmicrotime(&now);
336 		if (timevalcmp(&now, &end, >))
337 			return (0);
338 		left = end;
339 		timevalsub(&left, &now);
340 		hz = tvtohz(&left);
341 
342 		/*
343 		 * We have to wait for more. If the timer expires, we
344 		 * should return a 0-byte read.
345 		 */
346 		if (tp->t_flags & TF_ZOMBIE)
347 			return (0);
348 		else if (ioflag & IO_NDELAY)
349 			return (EWOULDBLOCK);
350 
351 		error = tty_timedwait(tp, &tp->t_inwait, hz);
352 		if (error)
353 			return (error == EWOULDBLOCK ? 0 : error);
354 	}
355 
356 	return (0);
357 }
358 
359 static int
360 ttydisc_read_raw_interbyte_timer(struct tty *tp, struct uio *uio, int ioflag)
361 {
362 	size_t vmin = tp->t_termios.c_cc[VMIN];
363 	ssize_t oresid = uio->uio_resid;
364 	int error;
365 
366 	MPASS(tp->t_termios.c_cc[VMIN] != 0);
367 	MPASS(tp->t_termios.c_cc[VTIME] != 0);
368 
369 	/*
370 	 * When using the interbyte timer, the timer should be started
371 	 * after the first byte has been received. We just call into the
372 	 * generic read timer code after we've received the first byte.
373 	 */
374 
375 	for (;;) {
376 		error = tty_wait_background(tp, curthread, SIGTTIN);
377 		if (error)
378 			return (error);
379 
380 		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
381 		    uio->uio_resid, 0);
382 		if (error)
383 			return (error);
384 		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
385 			return (0);
386 
387 		/*
388 		 * Not enough data, but we did receive some, which means
389 		 * we'll now start using the interbyte timer.
390 		 */
391 		if (oresid != uio->uio_resid)
392 			break;
393 
394 		/* We have to wait for more. */
395 		if (tp->t_flags & TF_ZOMBIE)
396 			return (0);
397 		else if (ioflag & IO_NDELAY)
398 			return (EWOULDBLOCK);
399 
400 		error = tty_wait(tp, &tp->t_inwait);
401 		if (error)
402 			return (error);
403 	}
404 
405 	return ttydisc_read_raw_read_timer(tp, uio, ioflag, oresid);
406 }
407 
408 int
409 ttydisc_read(struct tty *tp, struct uio *uio, int ioflag)
410 {
411 	int error;
412 
413 	tty_assert_locked(tp);
414 
415 	if (uio->uio_resid == 0)
416 		return (0);
417 
418 	if (CMP_FLAG(l, ICANON))
419 		error = ttydisc_read_canonical(tp, uio, ioflag);
420 	else if (tp->t_termios.c_cc[VTIME] == 0)
421 		error = ttydisc_read_raw_no_timer(tp, uio, ioflag);
422 	else if (tp->t_termios.c_cc[VMIN] == 0)
423 		error = ttydisc_read_raw_read_timer(tp, uio, ioflag,
424 		    uio->uio_resid);
425 	else
426 		error = ttydisc_read_raw_interbyte_timer(tp, uio, ioflag);
427 
428 	if (ttyinq_bytesleft(&tp->t_inq) >= tp->t_inlow ||
429 	    ttyinq_bytescanonicalized(&tp->t_inq) == 0) {
430 		/* Unset the input watermark when we've got enough space. */
431 		tty_hiwat_in_unblock(tp);
432 	}
433 
434 	return (error);
435 }
436 
437 static __inline unsigned int
438 ttydisc_findchar(const char *obstart, unsigned int oblen)
439 {
440 	const char *c = obstart;
441 
442 	while (oblen--) {
443 		if (CTL_VALID(*c))
444 			break;
445 		c++;
446 	}
447 
448 	return (c - obstart);
449 }
450 
451 static int
452 ttydisc_write_oproc(struct tty *tp, char c)
453 {
454 	unsigned int scnt, error;
455 
456 	MPASS(CMP_FLAG(o, OPOST));
457 	MPASS(CTL_VALID(c));
458 
459 #define PRINT_NORMAL() ttyoutq_write_nofrag(&tp->t_outq, &c, 1)
460 	switch (c) {
461 	case CEOF:
462 		/* End-of-text dropping. */
463 		if (CMP_FLAG(o, ONOEOT))
464 			return (0);
465 		return PRINT_NORMAL();
466 
467 	case CERASE2:
468 		/* Handle backspace to fix tab expansion. */
469 		if (PRINT_NORMAL() != 0)
470 			return (-1);
471 		if (tp->t_column > 0)
472 			tp->t_column--;
473 		return (0);
474 
475 	case CTAB:
476 		/* Tab expansion. */
477 		scnt = 8 - (tp->t_column & 7);
478 		if (CMP_FLAG(o, TAB3)) {
479 			error = ttyoutq_write_nofrag(&tp->t_outq,
480 			    "        ", scnt);
481 		} else {
482 			error = PRINT_NORMAL();
483 		}
484 		if (error)
485 			return (-1);
486 
487 		tp->t_column += scnt;
488 		MPASS((tp->t_column % 8) == 0);
489 		return (0);
490 
491 	case CNL:
492 		/* Newline conversion. */
493 		if (CMP_FLAG(o, ONLCR)) {
494 			/* Convert \n to \r\n. */
495 			error = ttyoutq_write_nofrag(&tp->t_outq, "\r\n", 2);
496 		} else {
497 			error = PRINT_NORMAL();
498 		}
499 		if (error)
500 			return (-1);
501 
502 		if (CMP_FLAG(o, ONLCR|ONLRET)) {
503 			tp->t_column = tp->t_writepos = 0;
504 			ttyinq_reprintpos_set(&tp->t_inq);
505 		}
506 		return (0);
507 
508 	case CCR:
509 		/* Carriage return to newline conversion. */
510 		if (CMP_FLAG(o, OCRNL))
511 			c = CNL;
512 		/* Omit carriage returns on column 0. */
513 		if (CMP_FLAG(o, ONOCR) && tp->t_column == 0)
514 			return (0);
515 		if (PRINT_NORMAL() != 0)
516 			return (-1);
517 
518 		tp->t_column = tp->t_writepos = 0;
519 		ttyinq_reprintpos_set(&tp->t_inq);
520 		return (0);
521 	}
522 
523 	/*
524 	 * Invisible control character. Print it, but don't
525 	 * increase the column count.
526 	 */
527 	return PRINT_NORMAL();
528 #undef PRINT_NORMAL
529 }
530 
531 /*
532  * Just like the old TTY implementation, we need to copy data in chunks
533  * into a temporary buffer. One of the reasons why we need to do this,
534  * is because output processing (only TAB3 though) may allow the buffer
535  * to grow eight times.
536  */
537 int
538 ttydisc_write(struct tty *tp, struct uio *uio, int ioflag)
539 {
540 	char ob[TTY_STACKBUF];
541 	char *obstart;
542 	int error = 0;
543 	unsigned int oblen = 0;
544 
545 	tty_assert_locked(tp);
546 
547 	if (tp->t_flags & TF_ZOMBIE)
548 		return (EIO);
549 
550 	/*
551 	 * We don't need to check whether the process is the foreground
552 	 * process group or if we have a carrier. This is already done
553 	 * in ttydev_write().
554 	 */
555 
556 	while (uio->uio_resid > 0) {
557 		unsigned int nlen;
558 
559 		MPASS(oblen == 0);
560 
561 		if (CMP_FLAG(l, FLUSHO)) {
562 			uio->uio_offset += uio->uio_resid;
563 			uio->uio_resid = 0;
564 			return (0);
565 		}
566 
567 		/* Step 1: read data. */
568 		obstart = ob;
569 		nlen = MIN(uio->uio_resid, sizeof ob);
570 		tty_unlock(tp);
571 		error = uiomove(ob, nlen, uio);
572 		tty_lock(tp);
573 		if (error != 0)
574 			break;
575 		oblen = nlen;
576 
577 		if (tty_gone(tp)) {
578 			error = ENXIO;
579 			break;
580 		}
581 
582 		MPASS(oblen > 0);
583 
584 		/* Step 2: process data. */
585 		do {
586 			unsigned int plen, wlen;
587 
588 			if (CMP_FLAG(l, FLUSHO)) {
589 				uio->uio_offset += uio->uio_resid;
590 				uio->uio_resid = 0;
591 				return (0);
592 			}
593 
594 			/* Search for special characters for post processing. */
595 			if (CMP_FLAG(o, OPOST)) {
596 				plen = ttydisc_findchar(obstart, oblen);
597 			} else {
598 				plen = oblen;
599 			}
600 
601 			if (plen == 0) {
602 				/*
603 				 * We're going to process a character
604 				 * that needs processing
605 				 */
606 				if (ttydisc_write_oproc(tp, *obstart) == 0) {
607 					obstart++;
608 					oblen--;
609 
610 					tp->t_writepos = tp->t_column;
611 					ttyinq_reprintpos_set(&tp->t_inq);
612 					continue;
613 				}
614 			} else {
615 				/* We're going to write regular data. */
616 				wlen = ttyoutq_write(&tp->t_outq, obstart, plen);
617 				obstart += wlen;
618 				oblen -= wlen;
619 				tp->t_column += wlen;
620 
621 				tp->t_writepos = tp->t_column;
622 				ttyinq_reprintpos_set(&tp->t_inq);
623 
624 				if (wlen == plen)
625 					continue;
626 			}
627 
628 			/* Watermark reached. Try to sleep. */
629 			tp->t_flags |= TF_HIWAT_OUT;
630 
631 			if (ioflag & IO_NDELAY) {
632 				error = EWOULDBLOCK;
633 				goto done;
634 			}
635 
636 			/*
637 			 * The driver may write back the data
638 			 * synchronously. Be sure to check the high
639 			 * water mark before going to sleep.
640 			 */
641 			ttydevsw_outwakeup(tp);
642 			if ((tp->t_flags & TF_HIWAT_OUT) == 0)
643 				continue;
644 
645 			error = tty_wait(tp, &tp->t_outwait);
646 			if (error)
647 				goto done;
648 
649 			if (tp->t_flags & TF_ZOMBIE) {
650 				error = EIO;
651 				goto done;
652 			}
653 		} while (oblen > 0);
654 	}
655 
656 done:
657 	if (!tty_gone(tp))
658 		ttydevsw_outwakeup(tp);
659 
660 	/*
661 	 * Add the amount of bytes that we didn't process back to the
662 	 * uio counters. We need to do this to make sure write() doesn't
663 	 * count the bytes we didn't store in the queue.
664 	 */
665 	uio->uio_resid += oblen;
666 	return (error);
667 }
668 
669 void
670 ttydisc_optimize(struct tty *tp)
671 {
672 	tty_assert_locked(tp);
673 
674 	if (ttyhook_hashook(tp, rint_bypass)) {
675 		tp->t_flags |= TF_BYPASS;
676 	} else if (ttyhook_hashook(tp, rint)) {
677 		tp->t_flags &= ~TF_BYPASS;
678 	} else if (!CMP_FLAG(i, ICRNL|IGNCR|IMAXBEL|INLCR|ISTRIP|IXON) &&
679 	    (!CMP_FLAG(i, BRKINT) || CMP_FLAG(i, IGNBRK)) &&
680 	    (!CMP_FLAG(i, PARMRK) ||
681 		CMP_FLAG(i, IGNPAR|IGNBRK) == (IGNPAR|IGNBRK)) &&
682 	    !CMP_FLAG(l, ECHO|ICANON|IEXTEN|ISIG|PENDIN)) {
683 		tp->t_flags |= TF_BYPASS;
684 	} else {
685 		tp->t_flags &= ~TF_BYPASS;
686 	}
687 }
688 
689 void
690 ttydisc_modem(struct tty *tp, int open)
691 {
692 
693 	tty_assert_locked(tp);
694 
695 	if (open)
696 		cv_broadcast(&tp->t_dcdwait);
697 
698 	/*
699 	 * Ignore modem status lines when CLOCAL is turned on, but don't
700 	 * enter the zombie state when the TTY isn't opened, because
701 	 * that would cause the TTY to be in zombie state after being
702 	 * opened.
703 	 */
704 	if (!tty_opened(tp) || CMP_FLAG(c, CLOCAL))
705 		return;
706 
707 	if (open == 0) {
708 		/*
709 		 * Lost carrier.
710 		 */
711 		tp->t_flags |= TF_ZOMBIE;
712 
713 		tty_signal_sessleader(tp, SIGHUP);
714 		tty_flush(tp, FREAD|FWRITE);
715 	} else {
716 		/*
717 		 * Carrier is back again.
718 		 */
719 
720 		/* XXX: what should we do here? */
721 	}
722 }
723 
724 static int
725 ttydisc_echo_force(struct tty *tp, char c, int quote)
726 {
727 
728 	if (CMP_FLAG(l, FLUSHO))
729 		return 0;
730 
731 	if (CMP_FLAG(o, OPOST) && CTL_ECHO(c, quote)) {
732 		/*
733 		 * Only perform postprocessing when OPOST is turned on
734 		 * and the character is an unquoted BS/TB/NL/CR.
735 		 */
736 		return ttydisc_write_oproc(tp, c);
737 	} else if (CMP_FLAG(l, ECHOCTL) && CTL_PRINT(c, quote)) {
738 		/*
739 		 * Only use ^X notation when ECHOCTL is turned on and
740 		 * we've got an quoted control character.
741 		 *
742 		 * Print backspaces when echoing an end-of-file.
743 		 */
744 		char ob[4] = "^?\b\b";
745 
746 		/* Print ^X notation. */
747 		if (c != 0x7f)
748 			ob[1] = c + 'A' - 1;
749 
750 		if (!quote && CMP_CC(VEOF, c)) {
751 			return ttyoutq_write_nofrag(&tp->t_outq, ob, 4);
752 		} else {
753 			tp->t_column += 2;
754 			return ttyoutq_write_nofrag(&tp->t_outq, ob, 2);
755 		}
756 	} else {
757 		/* Can just be printed. */
758 		tp->t_column++;
759 		return ttyoutq_write_nofrag(&tp->t_outq, &c, 1);
760 	}
761 }
762 
763 static int
764 ttydisc_echo(struct tty *tp, char c, int quote)
765 {
766 
767 	/*
768 	 * Only echo characters when ECHO is turned on, or ECHONL when
769 	 * the character is an unquoted newline.
770 	 */
771 	if (!CMP_FLAG(l, ECHO) &&
772 	    (!CMP_FLAG(l, ECHONL) || c != CNL || quote))
773 		return (0);
774 
775 	return ttydisc_echo_force(tp, c, quote);
776 }
777 
778 static void
779 ttydisc_reprint_char(void *d, char c, int quote)
780 {
781 	struct tty *tp = d;
782 
783 	ttydisc_echo(tp, c, quote);
784 }
785 
786 static void
787 ttydisc_reprint(struct tty *tp)
788 {
789 	cc_t c;
790 
791 	/* Print  ^R\n, followed by the line. */
792 	c = tp->t_termios.c_cc[VREPRINT];
793 	if (c != _POSIX_VDISABLE)
794 		ttydisc_echo(tp, c, 0);
795 	ttydisc_echo(tp, CNL, 0);
796 	ttyinq_reprintpos_reset(&tp->t_inq);
797 
798 	ttyinq_line_iterate_from_linestart(&tp->t_inq, ttydisc_reprint_char, tp);
799 }
800 
801 struct ttydisc_recalc_length {
802 	struct tty *tp;
803 	unsigned int curlen;
804 };
805 
806 static void
807 ttydisc_recalc_charlength(void *d, char c, int quote)
808 {
809 	struct ttydisc_recalc_length *data = d;
810 	struct tty *tp = data->tp;
811 
812 	if (CTL_PRINT(c, quote)) {
813 		if (CMP_FLAG(l, ECHOCTL))
814 			data->curlen += 2;
815 	} else if (c == CTAB) {
816 		data->curlen += 8 - (data->curlen & 7);
817 	} else {
818 		data->curlen++;
819 	}
820 }
821 
822 static unsigned int
823 ttydisc_recalc_linelength(struct tty *tp)
824 {
825 	struct ttydisc_recalc_length data = { tp, tp->t_writepos };
826 
827 	ttyinq_line_iterate_from_reprintpos(&tp->t_inq,
828 	    ttydisc_recalc_charlength, &data);
829 	return (data.curlen);
830 }
831 
832 static int
833 ttydisc_rubchar(struct tty *tp)
834 {
835 	char c;
836 	int quote;
837 	unsigned int prevpos, tablen;
838 
839 	if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
840 		return (-1);
841 	ttyinq_unputchar(&tp->t_inq);
842 
843 	if (CMP_FLAG(l, ECHO)) {
844 		/*
845 		 * Remove the character from the screen. This is even
846 		 * safe for characters that span multiple characters
847 		 * (tabs, quoted, etc).
848 		 */
849 		if (tp->t_writepos >= tp->t_column) {
850 			/* Retype the sentence. */
851 			ttydisc_reprint(tp);
852 		} else if (CMP_FLAG(l, ECHOE)) {
853 			if (CTL_PRINT(c, quote)) {
854 				/* Remove ^X formatted chars. */
855 				if (CMP_FLAG(l, ECHOCTL)) {
856 					tp->t_column -= 2;
857 					ttyoutq_write_nofrag(&tp->t_outq,
858 					    "\b\b  \b\b", 6);
859 				}
860 			} else if (c == ' ') {
861 				/* Space character needs no rubbing. */
862 				tp->t_column -= 1;
863 				ttyoutq_write_nofrag(&tp->t_outq, "\b", 1);
864 			} else if (c == CTAB) {
865 				/*
866 				 * Making backspace work with tabs is
867 				 * quite hard. Recalculate the length of
868 				 * this character and remove it.
869 				 *
870 				 * Because terminal settings could be
871 				 * changed while the line is being
872 				 * inserted, the calculations don't have
873 				 * to be correct. Make sure we keep the
874 				 * tab length within proper bounds.
875 				 */
876 				prevpos = ttydisc_recalc_linelength(tp);
877 				if (prevpos >= tp->t_column)
878 					tablen = 1;
879 				else
880 					tablen = tp->t_column - prevpos;
881 				if (tablen > 8)
882 					tablen = 8;
883 
884 				tp->t_column = prevpos;
885 				ttyoutq_write_nofrag(&tp->t_outq,
886 				    "\b\b\b\b\b\b\b\b", tablen);
887 				return (0);
888 			} else if ((tp->t_termios.c_iflag & IUTF8) != 0 &&
889 			    CTL_UTF8(c)) {
890 				uint8_t bytes[UTF8_STACKBUF] = { 0 };
891 				int curidx = UTF8_STACKBUF - 1, cwidth = 1,
892 				    nb = 0;
893 				teken_char_t codepoint;
894 
895 				/* Save current byte. */
896 				bytes[curidx] = c;
897 				curidx--;
898 				nb++;
899 				/* Loop back through inq until we hit the
900 				 * leading byte. */
901 				while (CTL_UTF8_CONT(c) && nb < UTF8_STACKBUF) {
902 					/*
903 					 * Check if we've reached the beginning
904 					 * of the line.
905 					 */
906 					if (ttyinq_peekchar(&tp->t_inq, &c,
907 					    &quote) != 0)
908 						break;
909 					ttyinq_unputchar(&tp->t_inq);
910 					bytes[curidx] = c;
911 					curidx--;
912 					nb++;
913 				}
914 				/*
915 				 * Shift array so that the leading
916 				 * byte ends up at idx 0.
917 				 */
918 				if (nb < UTF8_STACKBUF)
919 					memmove(&bytes[0], &bytes[curidx + 1],
920 					    nb * sizeof(uint8_t));
921 				/* Check for malformed UTF8 characters. */
922 				if (nb == UTF8_STACKBUF &&
923 				    CTL_UTF8_CONT(bytes[0])) {
924 					/*
925 					 * Place all bytes back into the inq and
926 					 * delete the last byte only.
927 					 */
928 					ttyinq_write(&tp->t_inq, bytes,
929 					    UTF8_STACKBUF, 0);
930 					ttyinq_unputchar(&tp->t_inq);
931 				} else {
932 					/* Find codepoint and width. */
933 					codepoint =
934 					    teken_utf8_bytes_to_codepoint(bytes,
935 						nb);
936 					if (codepoint ==
937 						TEKEN_UTF8_INVALID_CODEPOINT ||
938 					    (cwidth = teken_wcwidth(
939 						 codepoint)) == -1) {
940 						/*
941 						 * Place all bytes back into the
942 						 * inq and fall back to
943 						 * default behaviour.
944 						 */
945 						cwidth = 1;
946 						ttyinq_write(&tp->t_inq, bytes,
947 						    nb, 0);
948 						ttyinq_unputchar(&tp->t_inq);
949 					}
950 				}
951 				tp->t_column -= cwidth;
952 				/*
953 				 * Delete character by punching
954 				 * 'cwidth' spaces over it.
955 				 */
956 				if (cwidth == 1)
957 					ttyoutq_write_nofrag(&tp->t_outq,
958 					    "\b \b", 3);
959 				else if (cwidth == 2)
960 					ttyoutq_write_nofrag(&tp->t_outq,
961 					    "\b\b  \b\b", 6);
962 			} else {
963 				/*
964 				 * Remove a regular character by
965 				 * punching a space over it.
966 				 */
967 				tp->t_column -= 1;
968 				ttyoutq_write_nofrag(&tp->t_outq, "\b \b", 3);
969 			}
970 		} else {
971 			/* Don't print spaces. */
972 			ttydisc_echo(tp, tp->t_termios.c_cc[VERASE], 0);
973 		}
974 	}
975 
976 	return (0);
977 }
978 
979 static void
980 ttydisc_rubword(struct tty *tp)
981 {
982 	char c;
983 	int quote, alnum;
984 
985 	/* Strip whitespace first. */
986 	for (;;) {
987 		if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
988 			return;
989 		if (!CTL_WHITE(c))
990 			break;
991 		ttydisc_rubchar(tp);
992 	}
993 
994 	/*
995 	 * Record whether the last character from the previous iteration
996 	 * was alphanumeric or not. We need this to implement ALTWERASE.
997 	 */
998 	alnum = CTL_ALNUM(c);
999 	for (;;) {
1000 		ttydisc_rubchar(tp);
1001 
1002 		if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
1003 			return;
1004 		if (CTL_WHITE(c))
1005 			return;
1006 		if (CMP_FLAG(l, ALTWERASE) && CTL_ALNUM(c) != alnum)
1007 			return;
1008 	}
1009 }
1010 
1011 int
1012 ttydisc_rint(struct tty *tp, char c, int flags)
1013 {
1014 	int signal, quote = 0;
1015 	char ob[3] = { 0xff, 0x00 };
1016 	size_t ol;
1017 
1018 	tty_assert_locked(tp);
1019 
1020 	atomic_add_long(&tty_nin, 1);
1021 
1022 	if (ttyhook_hashook(tp, rint))
1023 		return ttyhook_rint(tp, c, flags);
1024 
1025 	if (tp->t_flags & TF_BYPASS)
1026 		goto processed;
1027 
1028 	if (flags) {
1029 		if (flags & TRE_BREAK) {
1030 			if (CMP_FLAG(i, IGNBRK)) {
1031 				/* Ignore break characters. */
1032 				return (0);
1033 			} else if (CMP_FLAG(i, BRKINT)) {
1034 				/* Generate SIGINT on break. */
1035 				tty_flush(tp, FREAD|FWRITE);
1036 				tty_signal_pgrp(tp, SIGINT);
1037 				return (0);
1038 			} else {
1039 				/* Just print it. */
1040 				goto parmrk;
1041 			}
1042 		} else if (flags & TRE_FRAMING ||
1043 		    (flags & TRE_PARITY && CMP_FLAG(i, INPCK))) {
1044 			if (CMP_FLAG(i, IGNPAR)) {
1045 				/* Ignore bad characters. */
1046 				return (0);
1047 			} else {
1048 				/* Just print it. */
1049 				goto parmrk;
1050 			}
1051 		}
1052 	}
1053 
1054 	/* Allow any character to perform a wakeup. */
1055 	if (CMP_FLAG(i, IXANY)) {
1056 		tp->t_flags &= ~TF_STOPPED;
1057 		tp->t_termios.c_lflag &= ~FLUSHO;
1058 	}
1059 
1060 	/* Remove the top bit. */
1061 	if (CMP_FLAG(i, ISTRIP))
1062 		c &= ~0x80;
1063 
1064 	/* Skip input processing when we want to print it literally. */
1065 	if (tp->t_flags & TF_LITERAL) {
1066 		tp->t_flags &= ~TF_LITERAL;
1067 		quote = 1;
1068 		goto processed;
1069 	}
1070 
1071 	/* Special control characters that are implementation dependent. */
1072 	if (CMP_FLAG(l, IEXTEN)) {
1073 		/* Accept the next character as literal. */
1074 		if (CMP_CC(VLNEXT, c)) {
1075 			if (CMP_FLAG(l, ECHO)) {
1076 				if (CMP_FLAG(l, ECHOE))
1077 					ttyoutq_write_nofrag(&tp->t_outq, "^\b", 2);
1078 				else
1079 					ttydisc_echo(tp, c, 0);
1080 			}
1081 			tp->t_flags |= TF_LITERAL;
1082 			return (0);
1083 		}
1084 		/* Discard processing */
1085 		if (CMP_CC(VDISCARD, c)) {
1086 			if (CMP_FLAG(l, FLUSHO)) {
1087 				tp->t_termios.c_lflag &= ~FLUSHO;
1088 			} else {
1089 				tty_flush(tp, FWRITE);
1090 				ttydisc_echo(tp, c, 0);
1091 				if (tp->t_inq.ti_end > 0)
1092 					ttydisc_reprint(tp);
1093 				tp->t_termios.c_lflag |= FLUSHO;
1094 			}
1095 		}
1096 	}
1097 
1098 	/*
1099 	 * Handle signal processing.
1100 	 */
1101 	if (CMP_FLAG(l, ISIG)) {
1102 		if (CMP_FLAG(l, ICANON|IEXTEN) == (ICANON|IEXTEN)) {
1103 			if (CMP_CC(VSTATUS, c)) {
1104 				tty_signal_pgrp(tp, SIGINFO);
1105 				return (0);
1106 			}
1107 		}
1108 
1109 		/*
1110 		 * When compared to the old implementation, this
1111 		 * implementation also flushes the output queue. POSIX
1112 		 * is really brief about this, but does makes us assume
1113 		 * we have to do so.
1114 		 */
1115 		signal = 0;
1116 		if (CMP_CC(VINTR, c)) {
1117 			signal = SIGINT;
1118 		} else if (CMP_CC(VQUIT, c)) {
1119 			signal = SIGQUIT;
1120 		} else if (CMP_CC(VSUSP, c)) {
1121 			signal = SIGTSTP;
1122 		}
1123 
1124 		if (signal != 0) {
1125 			/*
1126 			 * Echo the character before signalling the
1127 			 * processes.
1128 			 */
1129 			if (!CMP_FLAG(l, NOFLSH))
1130 				tty_flush(tp, FREAD|FWRITE);
1131 			ttydisc_echo(tp, c, 0);
1132 			tty_signal_pgrp(tp, signal);
1133 			return (0);
1134 		}
1135 	}
1136 
1137 	/*
1138 	 * Handle start/stop characters.
1139 	 */
1140 	if (CMP_FLAG(i, IXON)) {
1141 		if (CMP_CC(VSTOP, c)) {
1142 			/* Stop it if we aren't stopped yet. */
1143 			if ((tp->t_flags & TF_STOPPED) == 0) {
1144 				tp->t_flags |= TF_STOPPED;
1145 				return (0);
1146 			}
1147 			/*
1148 			 * Fallthrough:
1149 			 * When VSTART == VSTOP, we should make this key
1150 			 * toggle it.
1151 			 */
1152 			if (!CMP_CC(VSTART, c))
1153 				return (0);
1154 		}
1155 		if (CMP_CC(VSTART, c)) {
1156 			tp->t_flags &= ~TF_STOPPED;
1157 			return (0);
1158 		}
1159 	}
1160 
1161 	/* Conversion of CR and NL. */
1162 	switch (c) {
1163 	case CCR:
1164 		if (CMP_FLAG(i, IGNCR))
1165 			return (0);
1166 		if (CMP_FLAG(i, ICRNL))
1167 			c = CNL;
1168 		break;
1169 	case CNL:
1170 		if (CMP_FLAG(i, INLCR))
1171 			c = CCR;
1172 		break;
1173 	}
1174 
1175 	/* Canonical line editing. */
1176 	if (CMP_FLAG(l, ICANON)) {
1177 		if (CMP_CC(VERASE, c) || CMP_CC(VERASE2, c)) {
1178 			ttydisc_rubchar(tp);
1179 			return (0);
1180 		} else if (CMP_CC(VKILL, c)) {
1181 			while (ttydisc_rubchar(tp) == 0);
1182 			return (0);
1183 		} else if (CMP_FLAG(l, IEXTEN)) {
1184 			if (CMP_CC(VWERASE, c)) {
1185 				ttydisc_rubword(tp);
1186 				return (0);
1187 			} else if (CMP_CC(VREPRINT, c)) {
1188 				ttydisc_reprint(tp);
1189 				return (0);
1190 			}
1191 		}
1192 	}
1193 
1194 processed:
1195 	if (CMP_FLAG(i, PARMRK) && (unsigned char)c == 0xff) {
1196 		/* Print 0xff 0xff. */
1197 		ob[1] = 0xff;
1198 		ol = 2;
1199 		quote = 1;
1200 	} else {
1201 		ob[0] = c;
1202 		ol = 1;
1203 	}
1204 
1205 	goto print;
1206 
1207 parmrk:
1208 	if (CMP_FLAG(i, PARMRK)) {
1209 		/* Prepend 0xff 0x00 0x.. */
1210 		ob[2] = c;
1211 		ol = 3;
1212 		quote = 1;
1213 	} else {
1214 		ob[0] = c;
1215 		ol = 1;
1216 	}
1217 
1218 print:
1219 	/* See if we can store this on the input queue. */
1220 	if (ttyinq_write_nofrag(&tp->t_inq, ob, ol, quote) != 0) {
1221 		if (CMP_FLAG(i, IMAXBEL))
1222 			ttyoutq_write_nofrag(&tp->t_outq, "\a", 1);
1223 
1224 		/*
1225 		 * Prevent a deadlock here. It may be possible that a
1226 		 * user has entered so much data, there is no data
1227 		 * available to read(), but the buffers are full anyway.
1228 		 *
1229 		 * Only enter the high watermark if the device driver
1230 		 * can actually transmit something.
1231 		 */
1232 		if (ttyinq_bytescanonicalized(&tp->t_inq) == 0)
1233 			return (0);
1234 
1235 		tty_hiwat_in_block(tp);
1236 		return (-1);
1237 	}
1238 
1239 	/*
1240 	 * In raw mode, we canonicalize after receiving a single
1241 	 * character. Otherwise, we canonicalize when we receive a
1242 	 * newline, VEOL or VEOF, but only when it isn't quoted.
1243 	 */
1244 	if (!CMP_FLAG(l, ICANON) ||
1245 	    (!quote && (c == CNL || CMP_CC(VEOL, c) || CMP_CC(VEOF, c)))) {
1246 		ttyinq_canonicalize(&tp->t_inq);
1247 	}
1248 
1249 	ttydisc_echo(tp, c, quote);
1250 
1251 	return (0);
1252 }
1253 
1254 size_t
1255 ttydisc_rint_simple(struct tty *tp, const void *buf, size_t len)
1256 {
1257 	const char *cbuf;
1258 
1259 	if (ttydisc_can_bypass(tp))
1260 		return (ttydisc_rint_bypass(tp, buf, len));
1261 
1262 	for (cbuf = buf; len-- > 0; cbuf++) {
1263 		if (ttydisc_rint(tp, *cbuf, 0) != 0)
1264 			break;
1265 	}
1266 
1267 	return (cbuf - (const char *)buf);
1268 }
1269 
1270 size_t
1271 ttydisc_rint_bypass(struct tty *tp, const void *buf, size_t len)
1272 {
1273 	size_t ret;
1274 
1275 	tty_assert_locked(tp);
1276 
1277 	MPASS(tp->t_flags & TF_BYPASS);
1278 
1279 	atomic_add_long(&tty_nin, len);
1280 
1281 	if (ttyhook_hashook(tp, rint_bypass))
1282 		return ttyhook_rint_bypass(tp, buf, len);
1283 
1284 	ret = ttyinq_write(&tp->t_inq, buf, len, 0);
1285 	ttyinq_canonicalize(&tp->t_inq);
1286 	if (ret < len)
1287 		tty_hiwat_in_block(tp);
1288 
1289 	return (ret);
1290 }
1291 
1292 void
1293 ttydisc_rint_done(struct tty *tp)
1294 {
1295 
1296 	tty_assert_locked(tp);
1297 
1298 	if (ttyhook_hashook(tp, rint_done))
1299 		ttyhook_rint_done(tp);
1300 
1301 	/* Wake up readers. */
1302 	tty_wakeup(tp, FREAD);
1303 	/* Wake up driver for echo. */
1304 	ttydevsw_outwakeup(tp);
1305 }
1306 
1307 size_t
1308 ttydisc_rint_poll(struct tty *tp)
1309 {
1310 	size_t l;
1311 
1312 	tty_assert_locked(tp);
1313 
1314 	if (ttyhook_hashook(tp, rint_poll))
1315 		return ttyhook_rint_poll(tp);
1316 
1317 	/*
1318 	 * XXX: Still allow character input when there's no space in the
1319 	 * buffers, but we haven't entered the high watermark. This is
1320 	 * to allow backspace characters to be inserted when in
1321 	 * canonical mode.
1322 	 */
1323 	l = ttyinq_bytesleft(&tp->t_inq);
1324 	if (l == 0 && (tp->t_flags & TF_HIWAT_IN) == 0)
1325 		return (1);
1326 
1327 	return (l);
1328 }
1329 
1330 static void
1331 ttydisc_wakeup_watermark(struct tty *tp)
1332 {
1333 	size_t c;
1334 
1335 	c = ttyoutq_bytesleft(&tp->t_outq);
1336 	if (tp->t_flags & TF_HIWAT_OUT) {
1337 		/* Only allow us to run when we're below the watermark. */
1338 		if (c < tp->t_outlow)
1339 			return;
1340 
1341 		/* Reset the watermark. */
1342 		tp->t_flags &= ~TF_HIWAT_OUT;
1343 	} else {
1344 		/* Only run when we have data at all. */
1345 		if (c == 0)
1346 			return;
1347 	}
1348 	tty_wakeup(tp, FWRITE);
1349 }
1350 
1351 size_t
1352 ttydisc_getc(struct tty *tp, void *buf, size_t len)
1353 {
1354 
1355 	tty_assert_locked(tp);
1356 
1357 	if (tp->t_flags & TF_STOPPED)
1358 		return (0);
1359 
1360 	if (ttyhook_hashook(tp, getc_inject))
1361 		return ttyhook_getc_inject(tp, buf, len);
1362 
1363 	len = ttyoutq_read(&tp->t_outq, buf, len);
1364 
1365 	if (ttyhook_hashook(tp, getc_capture))
1366 		ttyhook_getc_capture(tp, buf, len);
1367 
1368 	ttydisc_wakeup_watermark(tp);
1369 	atomic_add_long(&tty_nout, len);
1370 
1371 	return (len);
1372 }
1373 
1374 int
1375 ttydisc_getc_uio(struct tty *tp, struct uio *uio)
1376 {
1377 	int error = 0;
1378 	ssize_t obytes = uio->uio_resid;
1379 	size_t len;
1380 	char buf[TTY_STACKBUF];
1381 
1382 	tty_assert_locked(tp);
1383 
1384 	if (tp->t_flags & TF_STOPPED)
1385 		return (0);
1386 
1387 	/*
1388 	 * When a TTY hook is attached, we cannot perform unbuffered
1389 	 * copying to userspace. Just call ttydisc_getc() and
1390 	 * temporarily store data in a shadow buffer.
1391 	 */
1392 	if (ttyhook_hashook(tp, getc_capture) ||
1393 	    ttyhook_hashook(tp, getc_inject)) {
1394 		while (uio->uio_resid > 0) {
1395 			/* Read to shadow buffer. */
1396 			len = ttydisc_getc(tp, buf,
1397 			    MIN(uio->uio_resid, sizeof buf));
1398 			if (len == 0)
1399 				break;
1400 
1401 			/* Copy to userspace. */
1402 			tty_unlock(tp);
1403 			error = uiomove(buf, len, uio);
1404 			tty_lock(tp);
1405 
1406 			if (error != 0)
1407 				break;
1408 		}
1409 	} else {
1410 		error = ttyoutq_read_uio(&tp->t_outq, tp, uio);
1411 
1412 		ttydisc_wakeup_watermark(tp);
1413 		atomic_add_long(&tty_nout, obytes - uio->uio_resid);
1414 	}
1415 
1416 	return (error);
1417 }
1418 
1419 size_t
1420 ttydisc_getc_poll(struct tty *tp)
1421 {
1422 
1423 	tty_assert_locked(tp);
1424 
1425 	if (tp->t_flags & TF_STOPPED)
1426 		return (0);
1427 
1428 	if (ttyhook_hashook(tp, getc_poll))
1429 		return ttyhook_getc_poll(tp);
1430 
1431 	return ttyoutq_bytesused(&tp->t_outq);
1432 }
1433 
1434 /*
1435  * XXX: not really related to the TTYDISC, but we'd better put
1436  * tty_putchar() here, because we need to perform proper output
1437  * processing.
1438  */
1439 
1440 int
1441 tty_putstrn(struct tty *tp, const char *p, size_t n)
1442 {
1443 	size_t i;
1444 
1445 	tty_assert_locked(tp);
1446 
1447 	if (tty_gone(tp))
1448 		return (-1);
1449 
1450 	for (i = 0; i < n; i++)
1451 		ttydisc_echo_force(tp, p[i], 0);
1452 
1453 	tp->t_writepos = tp->t_column;
1454 	ttyinq_reprintpos_set(&tp->t_inq);
1455 
1456 	ttydevsw_outwakeup(tp);
1457 	return (0);
1458 }
1459 
1460 int
1461 tty_putchar(struct tty *tp, char c)
1462 {
1463 	return (tty_putstrn(tp, &c, 1));
1464 }
1465