xref: /freebsd/sys/kern/tty_ttydisc.c (revision 06c3fb2749bda94cb5201f81ffdb8fa6c3161b2e)
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 static int
116 ttydisc_read_canonical(struct tty *tp, struct uio *uio, int ioflag)
117 {
118 	char breakc[4] = { CNL }; /* enough to hold \n, VEOF and VEOL. */
119 	int error;
120 	size_t clen, flen = 0, n = 1;
121 	unsigned char lastc = _POSIX_VDISABLE;
122 
123 #define BREAK_ADD(c) do { \
124 	if (tp->t_termios.c_cc[c] != _POSIX_VDISABLE)	\
125 		breakc[n++] = tp->t_termios.c_cc[c];	\
126 } while (0)
127 	/* Determine which characters we should trigger on. */
128 	BREAK_ADD(VEOF);
129 	BREAK_ADD(VEOL);
130 #undef BREAK_ADD
131 	breakc[n] = '\0';
132 
133 	do {
134 		error = tty_wait_background(tp, curthread, SIGTTIN);
135 		if (error)
136 			return (error);
137 
138 		/*
139 		 * Quite a tricky case: unlike the old TTY
140 		 * implementation, this implementation copies data back
141 		 * to userspace in large chunks. Unfortunately, we can't
142 		 * calculate the line length on beforehand if it crosses
143 		 * ttyinq_block boundaries, because multiple reads could
144 		 * then make this code read beyond the newline.
145 		 *
146 		 * This is why we limit the read to:
147 		 * - The size the user has requested
148 		 * - The blocksize (done in tty_inq.c)
149 		 * - The amount of bytes until the newline
150 		 *
151 		 * This causes the line length to be recalculated after
152 		 * each block has been copied to userspace. This will
153 		 * cause the TTY layer to return data in chunks using
154 		 * the blocksize (except the first and last blocks).
155 		 */
156 		clen = ttyinq_findchar(&tp->t_inq, breakc, uio->uio_resid,
157 		    &lastc);
158 
159 		/* No more data. */
160 		if (clen == 0) {
161 			if (tp->t_flags & TF_ZOMBIE)
162 				return (0);
163 			else if (ioflag & IO_NDELAY)
164 				return (EWOULDBLOCK);
165 
166 			error = tty_wait(tp, &tp->t_inwait);
167 			if (error)
168 				return (error);
169 			continue;
170 		}
171 
172 		/* Don't send the EOF char back to userspace. */
173 		if (CMP_CC(VEOF, lastc))
174 			flen = 1;
175 
176 		MPASS(flen <= clen);
177 
178 		/* Read and throw away the EOF character. */
179 		error = ttyinq_read_uio(&tp->t_inq, tp, uio, clen, flen);
180 		if (error)
181 			return (error);
182 
183 	} while (uio->uio_resid > 0 && lastc == _POSIX_VDISABLE);
184 
185 	return (0);
186 }
187 
188 static int
189 ttydisc_read_raw_no_timer(struct tty *tp, struct uio *uio, int ioflag)
190 {
191 	size_t vmin = tp->t_termios.c_cc[VMIN];
192 	ssize_t oresid = uio->uio_resid;
193 	int error;
194 
195 	MPASS(tp->t_termios.c_cc[VTIME] == 0);
196 
197 	/*
198 	 * This routine implements the easy cases of read()s while in
199 	 * non-canonical mode, namely case B and D, where we don't have
200 	 * any timers at all.
201 	 */
202 
203 	for (;;) {
204 		error = tty_wait_background(tp, curthread, SIGTTIN);
205 		if (error)
206 			return (error);
207 
208 		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
209 		    uio->uio_resid, 0);
210 		if (error)
211 			return (error);
212 		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
213 			return (0);
214 
215 		/* We have to wait for more. */
216 		if (tp->t_flags & TF_ZOMBIE)
217 			return (0);
218 		else if (ioflag & IO_NDELAY)
219 			return (EWOULDBLOCK);
220 
221 		error = tty_wait(tp, &tp->t_inwait);
222 		if (error)
223 			return (error);
224 	}
225 }
226 
227 static int
228 ttydisc_read_raw_read_timer(struct tty *tp, struct uio *uio, int ioflag,
229     int oresid)
230 {
231 	size_t vmin = MAX(tp->t_termios.c_cc[VMIN], 1);
232 	unsigned int vtime = tp->t_termios.c_cc[VTIME];
233 	struct timeval end, now, left;
234 	int error, hz;
235 
236 	MPASS(tp->t_termios.c_cc[VTIME] != 0);
237 
238 	/* Determine when the read should be expired. */
239 	end.tv_sec = vtime / 10;
240 	end.tv_usec = (vtime % 10) * 100000;
241 	getmicrotime(&now);
242 	timevaladd(&end, &now);
243 
244 	for (;;) {
245 		error = tty_wait_background(tp, curthread, SIGTTIN);
246 		if (error)
247 			return (error);
248 
249 		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
250 		    uio->uio_resid, 0);
251 		if (error)
252 			return (error);
253 		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
254 			return (0);
255 
256 		/* Calculate how long we should wait. */
257 		getmicrotime(&now);
258 		if (timevalcmp(&now, &end, >))
259 			return (0);
260 		left = end;
261 		timevalsub(&left, &now);
262 		hz = tvtohz(&left);
263 
264 		/*
265 		 * We have to wait for more. If the timer expires, we
266 		 * should return a 0-byte read.
267 		 */
268 		if (tp->t_flags & TF_ZOMBIE)
269 			return (0);
270 		else if (ioflag & IO_NDELAY)
271 			return (EWOULDBLOCK);
272 
273 		error = tty_timedwait(tp, &tp->t_inwait, hz);
274 		if (error)
275 			return (error == EWOULDBLOCK ? 0 : error);
276 	}
277 
278 	return (0);
279 }
280 
281 static int
282 ttydisc_read_raw_interbyte_timer(struct tty *tp, struct uio *uio, int ioflag)
283 {
284 	size_t vmin = tp->t_termios.c_cc[VMIN];
285 	ssize_t oresid = uio->uio_resid;
286 	int error;
287 
288 	MPASS(tp->t_termios.c_cc[VMIN] != 0);
289 	MPASS(tp->t_termios.c_cc[VTIME] != 0);
290 
291 	/*
292 	 * When using the interbyte timer, the timer should be started
293 	 * after the first byte has been received. We just call into the
294 	 * generic read timer code after we've received the first byte.
295 	 */
296 
297 	for (;;) {
298 		error = tty_wait_background(tp, curthread, SIGTTIN);
299 		if (error)
300 			return (error);
301 
302 		error = ttyinq_read_uio(&tp->t_inq, tp, uio,
303 		    uio->uio_resid, 0);
304 		if (error)
305 			return (error);
306 		if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
307 			return (0);
308 
309 		/*
310 		 * Not enough data, but we did receive some, which means
311 		 * we'll now start using the interbyte timer.
312 		 */
313 		if (oresid != uio->uio_resid)
314 			break;
315 
316 		/* We have to wait for more. */
317 		if (tp->t_flags & TF_ZOMBIE)
318 			return (0);
319 		else if (ioflag & IO_NDELAY)
320 			return (EWOULDBLOCK);
321 
322 		error = tty_wait(tp, &tp->t_inwait);
323 		if (error)
324 			return (error);
325 	}
326 
327 	return ttydisc_read_raw_read_timer(tp, uio, ioflag, oresid);
328 }
329 
330 int
331 ttydisc_read(struct tty *tp, struct uio *uio, int ioflag)
332 {
333 	int error;
334 
335 	tty_assert_locked(tp);
336 
337 	if (uio->uio_resid == 0)
338 		return (0);
339 
340 	if (CMP_FLAG(l, ICANON))
341 		error = ttydisc_read_canonical(tp, uio, ioflag);
342 	else if (tp->t_termios.c_cc[VTIME] == 0)
343 		error = ttydisc_read_raw_no_timer(tp, uio, ioflag);
344 	else if (tp->t_termios.c_cc[VMIN] == 0)
345 		error = ttydisc_read_raw_read_timer(tp, uio, ioflag,
346 		    uio->uio_resid);
347 	else
348 		error = ttydisc_read_raw_interbyte_timer(tp, uio, ioflag);
349 
350 	if (ttyinq_bytesleft(&tp->t_inq) >= tp->t_inlow ||
351 	    ttyinq_bytescanonicalized(&tp->t_inq) == 0) {
352 		/* Unset the input watermark when we've got enough space. */
353 		tty_hiwat_in_unblock(tp);
354 	}
355 
356 	return (error);
357 }
358 
359 static __inline unsigned int
360 ttydisc_findchar(const char *obstart, unsigned int oblen)
361 {
362 	const char *c = obstart;
363 
364 	while (oblen--) {
365 		if (CTL_VALID(*c))
366 			break;
367 		c++;
368 	}
369 
370 	return (c - obstart);
371 }
372 
373 static int
374 ttydisc_write_oproc(struct tty *tp, char c)
375 {
376 	unsigned int scnt, error;
377 
378 	MPASS(CMP_FLAG(o, OPOST));
379 	MPASS(CTL_VALID(c));
380 
381 #define PRINT_NORMAL() ttyoutq_write_nofrag(&tp->t_outq, &c, 1)
382 	switch (c) {
383 	case CEOF:
384 		/* End-of-text dropping. */
385 		if (CMP_FLAG(o, ONOEOT))
386 			return (0);
387 		return PRINT_NORMAL();
388 
389 	case CERASE2:
390 		/* Handle backspace to fix tab expansion. */
391 		if (PRINT_NORMAL() != 0)
392 			return (-1);
393 		if (tp->t_column > 0)
394 			tp->t_column--;
395 		return (0);
396 
397 	case CTAB:
398 		/* Tab expansion. */
399 		scnt = 8 - (tp->t_column & 7);
400 		if (CMP_FLAG(o, TAB3)) {
401 			error = ttyoutq_write_nofrag(&tp->t_outq,
402 			    "        ", scnt);
403 		} else {
404 			error = PRINT_NORMAL();
405 		}
406 		if (error)
407 			return (-1);
408 
409 		tp->t_column += scnt;
410 		MPASS((tp->t_column % 8) == 0);
411 		return (0);
412 
413 	case CNL:
414 		/* Newline conversion. */
415 		if (CMP_FLAG(o, ONLCR)) {
416 			/* Convert \n to \r\n. */
417 			error = ttyoutq_write_nofrag(&tp->t_outq, "\r\n", 2);
418 		} else {
419 			error = PRINT_NORMAL();
420 		}
421 		if (error)
422 			return (-1);
423 
424 		if (CMP_FLAG(o, ONLCR|ONLRET)) {
425 			tp->t_column = tp->t_writepos = 0;
426 			ttyinq_reprintpos_set(&tp->t_inq);
427 		}
428 		return (0);
429 
430 	case CCR:
431 		/* Carriage return to newline conversion. */
432 		if (CMP_FLAG(o, OCRNL))
433 			c = CNL;
434 		/* Omit carriage returns on column 0. */
435 		if (CMP_FLAG(o, ONOCR) && tp->t_column == 0)
436 			return (0);
437 		if (PRINT_NORMAL() != 0)
438 			return (-1);
439 
440 		tp->t_column = tp->t_writepos = 0;
441 		ttyinq_reprintpos_set(&tp->t_inq);
442 		return (0);
443 	}
444 
445 	/*
446 	 * Invisible control character. Print it, but don't
447 	 * increase the column count.
448 	 */
449 	return PRINT_NORMAL();
450 #undef PRINT_NORMAL
451 }
452 
453 /*
454  * Just like the old TTY implementation, we need to copy data in chunks
455  * into a temporary buffer. One of the reasons why we need to do this,
456  * is because output processing (only TAB3 though) may allow the buffer
457  * to grow eight times.
458  */
459 int
460 ttydisc_write(struct tty *tp, struct uio *uio, int ioflag)
461 {
462 	char ob[TTY_STACKBUF];
463 	char *obstart;
464 	int error = 0;
465 	unsigned int oblen = 0;
466 
467 	tty_assert_locked(tp);
468 
469 	if (tp->t_flags & TF_ZOMBIE)
470 		return (EIO);
471 
472 	/*
473 	 * We don't need to check whether the process is the foreground
474 	 * process group or if we have a carrier. This is already done
475 	 * in ttydev_write().
476 	 */
477 
478 	while (uio->uio_resid > 0) {
479 		unsigned int nlen;
480 
481 		MPASS(oblen == 0);
482 
483 		if (CMP_FLAG(l, FLUSHO)) {
484 			uio->uio_offset += uio->uio_resid;
485 			uio->uio_resid = 0;
486 			return (0);
487 		}
488 
489 		/* Step 1: read data. */
490 		obstart = ob;
491 		nlen = MIN(uio->uio_resid, sizeof ob);
492 		tty_unlock(tp);
493 		error = uiomove(ob, nlen, uio);
494 		tty_lock(tp);
495 		if (error != 0)
496 			break;
497 		oblen = nlen;
498 
499 		if (tty_gone(tp)) {
500 			error = ENXIO;
501 			break;
502 		}
503 
504 		MPASS(oblen > 0);
505 
506 		/* Step 2: process data. */
507 		do {
508 			unsigned int plen, wlen;
509 
510 			if (CMP_FLAG(l, FLUSHO)) {
511 				uio->uio_offset += uio->uio_resid;
512 				uio->uio_resid = 0;
513 				return (0);
514 			}
515 
516 			/* Search for special characters for post processing. */
517 			if (CMP_FLAG(o, OPOST)) {
518 				plen = ttydisc_findchar(obstart, oblen);
519 			} else {
520 				plen = oblen;
521 			}
522 
523 			if (plen == 0) {
524 				/*
525 				 * We're going to process a character
526 				 * that needs processing
527 				 */
528 				if (ttydisc_write_oproc(tp, *obstart) == 0) {
529 					obstart++;
530 					oblen--;
531 
532 					tp->t_writepos = tp->t_column;
533 					ttyinq_reprintpos_set(&tp->t_inq);
534 					continue;
535 				}
536 			} else {
537 				/* We're going to write regular data. */
538 				wlen = ttyoutq_write(&tp->t_outq, obstart, plen);
539 				obstart += wlen;
540 				oblen -= wlen;
541 				tp->t_column += wlen;
542 
543 				tp->t_writepos = tp->t_column;
544 				ttyinq_reprintpos_set(&tp->t_inq);
545 
546 				if (wlen == plen)
547 					continue;
548 			}
549 
550 			/* Watermark reached. Try to sleep. */
551 			tp->t_flags |= TF_HIWAT_OUT;
552 
553 			if (ioflag & IO_NDELAY) {
554 				error = EWOULDBLOCK;
555 				goto done;
556 			}
557 
558 			/*
559 			 * The driver may write back the data
560 			 * synchronously. Be sure to check the high
561 			 * water mark before going to sleep.
562 			 */
563 			ttydevsw_outwakeup(tp);
564 			if ((tp->t_flags & TF_HIWAT_OUT) == 0)
565 				continue;
566 
567 			error = tty_wait(tp, &tp->t_outwait);
568 			if (error)
569 				goto done;
570 
571 			if (tp->t_flags & TF_ZOMBIE) {
572 				error = EIO;
573 				goto done;
574 			}
575 		} while (oblen > 0);
576 	}
577 
578 done:
579 	if (!tty_gone(tp))
580 		ttydevsw_outwakeup(tp);
581 
582 	/*
583 	 * Add the amount of bytes that we didn't process back to the
584 	 * uio counters. We need to do this to make sure write() doesn't
585 	 * count the bytes we didn't store in the queue.
586 	 */
587 	uio->uio_resid += oblen;
588 	return (error);
589 }
590 
591 void
592 ttydisc_optimize(struct tty *tp)
593 {
594 	tty_assert_locked(tp);
595 
596 	if (ttyhook_hashook(tp, rint_bypass)) {
597 		tp->t_flags |= TF_BYPASS;
598 	} else if (ttyhook_hashook(tp, rint)) {
599 		tp->t_flags &= ~TF_BYPASS;
600 	} else if (!CMP_FLAG(i, ICRNL|IGNCR|IMAXBEL|INLCR|ISTRIP|IXON) &&
601 	    (!CMP_FLAG(i, BRKINT) || CMP_FLAG(i, IGNBRK)) &&
602 	    (!CMP_FLAG(i, PARMRK) ||
603 		CMP_FLAG(i, IGNPAR|IGNBRK) == (IGNPAR|IGNBRK)) &&
604 	    !CMP_FLAG(l, ECHO|ICANON|IEXTEN|ISIG|PENDIN)) {
605 		tp->t_flags |= TF_BYPASS;
606 	} else {
607 		tp->t_flags &= ~TF_BYPASS;
608 	}
609 }
610 
611 void
612 ttydisc_modem(struct tty *tp, int open)
613 {
614 
615 	tty_assert_locked(tp);
616 
617 	if (open)
618 		cv_broadcast(&tp->t_dcdwait);
619 
620 	/*
621 	 * Ignore modem status lines when CLOCAL is turned on, but don't
622 	 * enter the zombie state when the TTY isn't opened, because
623 	 * that would cause the TTY to be in zombie state after being
624 	 * opened.
625 	 */
626 	if (!tty_opened(tp) || CMP_FLAG(c, CLOCAL))
627 		return;
628 
629 	if (open == 0) {
630 		/*
631 		 * Lost carrier.
632 		 */
633 		tp->t_flags |= TF_ZOMBIE;
634 
635 		tty_signal_sessleader(tp, SIGHUP);
636 		tty_flush(tp, FREAD|FWRITE);
637 	} else {
638 		/*
639 		 * Carrier is back again.
640 		 */
641 
642 		/* XXX: what should we do here? */
643 	}
644 }
645 
646 static int
647 ttydisc_echo_force(struct tty *tp, char c, int quote)
648 {
649 
650 	if (CMP_FLAG(l, FLUSHO))
651 		return 0;
652 
653 	if (CMP_FLAG(o, OPOST) && CTL_ECHO(c, quote)) {
654 		/*
655 		 * Only perform postprocessing when OPOST is turned on
656 		 * and the character is an unquoted BS/TB/NL/CR.
657 		 */
658 		return ttydisc_write_oproc(tp, c);
659 	} else if (CMP_FLAG(l, ECHOCTL) && CTL_PRINT(c, quote)) {
660 		/*
661 		 * Only use ^X notation when ECHOCTL is turned on and
662 		 * we've got an quoted control character.
663 		 *
664 		 * Print backspaces when echoing an end-of-file.
665 		 */
666 		char ob[4] = "^?\b\b";
667 
668 		/* Print ^X notation. */
669 		if (c != 0x7f)
670 			ob[1] = c + 'A' - 1;
671 
672 		if (!quote && CMP_CC(VEOF, c)) {
673 			return ttyoutq_write_nofrag(&tp->t_outq, ob, 4);
674 		} else {
675 			tp->t_column += 2;
676 			return ttyoutq_write_nofrag(&tp->t_outq, ob, 2);
677 		}
678 	} else {
679 		/* Can just be printed. */
680 		tp->t_column++;
681 		return ttyoutq_write_nofrag(&tp->t_outq, &c, 1);
682 	}
683 }
684 
685 static int
686 ttydisc_echo(struct tty *tp, char c, int quote)
687 {
688 
689 	/*
690 	 * Only echo characters when ECHO is turned on, or ECHONL when
691 	 * the character is an unquoted newline.
692 	 */
693 	if (!CMP_FLAG(l, ECHO) &&
694 	    (!CMP_FLAG(l, ECHONL) || c != CNL || quote))
695 		return (0);
696 
697 	return ttydisc_echo_force(tp, c, quote);
698 }
699 
700 static void
701 ttydisc_reprint_char(void *d, char c, int quote)
702 {
703 	struct tty *tp = d;
704 
705 	ttydisc_echo(tp, c, quote);
706 }
707 
708 static void
709 ttydisc_reprint(struct tty *tp)
710 {
711 	cc_t c;
712 
713 	/* Print  ^R\n, followed by the line. */
714 	c = tp->t_termios.c_cc[VREPRINT];
715 	if (c != _POSIX_VDISABLE)
716 		ttydisc_echo(tp, c, 0);
717 	ttydisc_echo(tp, CNL, 0);
718 	ttyinq_reprintpos_reset(&tp->t_inq);
719 
720 	ttyinq_line_iterate_from_linestart(&tp->t_inq, ttydisc_reprint_char, tp);
721 }
722 
723 struct ttydisc_recalc_length {
724 	struct tty *tp;
725 	unsigned int curlen;
726 };
727 
728 static void
729 ttydisc_recalc_charlength(void *d, char c, int quote)
730 {
731 	struct ttydisc_recalc_length *data = d;
732 	struct tty *tp = data->tp;
733 
734 	if (CTL_PRINT(c, quote)) {
735 		if (CMP_FLAG(l, ECHOCTL))
736 			data->curlen += 2;
737 	} else if (c == CTAB) {
738 		data->curlen += 8 - (data->curlen & 7);
739 	} else {
740 		data->curlen++;
741 	}
742 }
743 
744 static unsigned int
745 ttydisc_recalc_linelength(struct tty *tp)
746 {
747 	struct ttydisc_recalc_length data = { tp, tp->t_writepos };
748 
749 	ttyinq_line_iterate_from_reprintpos(&tp->t_inq,
750 	    ttydisc_recalc_charlength, &data);
751 	return (data.curlen);
752 }
753 
754 static int
755 ttydisc_rubchar(struct tty *tp)
756 {
757 	char c;
758 	int quote;
759 	unsigned int prevpos, tablen;
760 
761 	if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
762 		return (-1);
763 	ttyinq_unputchar(&tp->t_inq);
764 
765 	if (CMP_FLAG(l, ECHO)) {
766 		/*
767 		 * Remove the character from the screen. This is even
768 		 * safe for characters that span multiple characters
769 		 * (tabs, quoted, etc).
770 		 */
771 		if (tp->t_writepos >= tp->t_column) {
772 			/* Retype the sentence. */
773 			ttydisc_reprint(tp);
774 		} else if (CMP_FLAG(l, ECHOE)) {
775 			if (CTL_PRINT(c, quote)) {
776 				/* Remove ^X formatted chars. */
777 				if (CMP_FLAG(l, ECHOCTL)) {
778 					tp->t_column -= 2;
779 					ttyoutq_write_nofrag(&tp->t_outq,
780 					    "\b\b  \b\b", 6);
781 				}
782 			} else if (c == ' ') {
783 				/* Space character needs no rubbing. */
784 				tp->t_column -= 1;
785 				ttyoutq_write_nofrag(&tp->t_outq, "\b", 1);
786 			} else if (c == CTAB) {
787 				/*
788 				 * Making backspace work with tabs is
789 				 * quite hard. Recalculate the length of
790 				 * this character and remove it.
791 				 *
792 				 * Because terminal settings could be
793 				 * changed while the line is being
794 				 * inserted, the calculations don't have
795 				 * to be correct. Make sure we keep the
796 				 * tab length within proper bounds.
797 				 */
798 				prevpos = ttydisc_recalc_linelength(tp);
799 				if (prevpos >= tp->t_column)
800 					tablen = 1;
801 				else
802 					tablen = tp->t_column - prevpos;
803 				if (tablen > 8)
804 					tablen = 8;
805 
806 				tp->t_column = prevpos;
807 				ttyoutq_write_nofrag(&tp->t_outq,
808 				    "\b\b\b\b\b\b\b\b", tablen);
809 				return (0);
810 			} else if ((tp->t_termios.c_iflag & IUTF8) != 0 &&
811 			    CTL_UTF8(c)) {
812 				uint8_t bytes[UTF8_STACKBUF] = { 0 };
813 				int curidx = UTF8_STACKBUF - 1, cwidth = 1,
814 				    nb = 0;
815 				teken_char_t codepoint;
816 
817 				/* Save current byte. */
818 				bytes[curidx] = c;
819 				curidx--;
820 				nb++;
821 				/* Loop back through inq until we hit the
822 				 * leading byte. */
823 				while (CTL_UTF8_CONT(c) && nb < UTF8_STACKBUF) {
824 					/*
825 					 * Check if we've reached the beginning
826 					 * of the line.
827 					 */
828 					if (ttyinq_peekchar(&tp->t_inq, &c,
829 					    &quote) != 0)
830 						break;
831 					ttyinq_unputchar(&tp->t_inq);
832 					bytes[curidx] = c;
833 					curidx--;
834 					nb++;
835 				}
836 				/*
837 				 * Shift array so that the leading
838 				 * byte ends up at idx 0.
839 				 */
840 				if (nb < UTF8_STACKBUF)
841 					memmove(&bytes[0], &bytes[curidx + 1],
842 					    nb * sizeof(uint8_t));
843 				/* Check for malformed UTF8 characters. */
844 				if (nb == UTF8_STACKBUF &&
845 				    CTL_UTF8_CONT(bytes[0])) {
846 					/*
847 					 * Place all bytes back into the inq and
848 					 * delete the last byte only.
849 					 */
850 					ttyinq_write(&tp->t_inq, bytes,
851 					    UTF8_STACKBUF, 0);
852 					ttyinq_unputchar(&tp->t_inq);
853 				} else {
854 					/* Find codepoint and width. */
855 					codepoint =
856 					    teken_utf8_bytes_to_codepoint(bytes,
857 						nb);
858 					if (codepoint ==
859 						TEKEN_UTF8_INVALID_CODEPOINT ||
860 					    (cwidth = teken_wcwidth(
861 						 codepoint)) == -1) {
862 						/*
863 						 * Place all bytes back into the
864 						 * inq and fall back to
865 						 * default behaviour.
866 						 */
867 						cwidth = 1;
868 						ttyinq_write(&tp->t_inq, bytes,
869 						    nb, 0);
870 						ttyinq_unputchar(&tp->t_inq);
871 					}
872 				}
873 				tp->t_column -= cwidth;
874 				/*
875 				 * Delete character by punching
876 				 * 'cwidth' spaces over it.
877 				 */
878 				if (cwidth == 1)
879 					ttyoutq_write_nofrag(&tp->t_outq,
880 					    "\b \b", 3);
881 				else if (cwidth == 2)
882 					ttyoutq_write_nofrag(&tp->t_outq,
883 					    "\b\b  \b\b", 6);
884 			} else {
885 				/*
886 				 * Remove a regular character by
887 				 * punching a space over it.
888 				 */
889 				tp->t_column -= 1;
890 				ttyoutq_write_nofrag(&tp->t_outq, "\b \b", 3);
891 			}
892 		} else {
893 			/* Don't print spaces. */
894 			ttydisc_echo(tp, tp->t_termios.c_cc[VERASE], 0);
895 		}
896 	}
897 
898 	return (0);
899 }
900 
901 static void
902 ttydisc_rubword(struct tty *tp)
903 {
904 	char c;
905 	int quote, alnum;
906 
907 	/* Strip whitespace first. */
908 	for (;;) {
909 		if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
910 			return;
911 		if (!CTL_WHITE(c))
912 			break;
913 		ttydisc_rubchar(tp);
914 	}
915 
916 	/*
917 	 * Record whether the last character from the previous iteration
918 	 * was alphanumeric or not. We need this to implement ALTWERASE.
919 	 */
920 	alnum = CTL_ALNUM(c);
921 	for (;;) {
922 		ttydisc_rubchar(tp);
923 
924 		if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
925 			return;
926 		if (CTL_WHITE(c))
927 			return;
928 		if (CMP_FLAG(l, ALTWERASE) && CTL_ALNUM(c) != alnum)
929 			return;
930 	}
931 }
932 
933 int
934 ttydisc_rint(struct tty *tp, char c, int flags)
935 {
936 	int signal, quote = 0;
937 	char ob[3] = { 0xff, 0x00 };
938 	size_t ol;
939 
940 	tty_assert_locked(tp);
941 
942 	atomic_add_long(&tty_nin, 1);
943 
944 	if (ttyhook_hashook(tp, rint))
945 		return ttyhook_rint(tp, c, flags);
946 
947 	if (tp->t_flags & TF_BYPASS)
948 		goto processed;
949 
950 	if (flags) {
951 		if (flags & TRE_BREAK) {
952 			if (CMP_FLAG(i, IGNBRK)) {
953 				/* Ignore break characters. */
954 				return (0);
955 			} else if (CMP_FLAG(i, BRKINT)) {
956 				/* Generate SIGINT on break. */
957 				tty_flush(tp, FREAD|FWRITE);
958 				tty_signal_pgrp(tp, SIGINT);
959 				return (0);
960 			} else {
961 				/* Just print it. */
962 				goto parmrk;
963 			}
964 		} else if (flags & TRE_FRAMING ||
965 		    (flags & TRE_PARITY && CMP_FLAG(i, INPCK))) {
966 			if (CMP_FLAG(i, IGNPAR)) {
967 				/* Ignore bad characters. */
968 				return (0);
969 			} else {
970 				/* Just print it. */
971 				goto parmrk;
972 			}
973 		}
974 	}
975 
976 	/* Allow any character to perform a wakeup. */
977 	if (CMP_FLAG(i, IXANY)) {
978 		tp->t_flags &= ~TF_STOPPED;
979 		tp->t_termios.c_lflag &= ~FLUSHO;
980 	}
981 
982 	/* Remove the top bit. */
983 	if (CMP_FLAG(i, ISTRIP))
984 		c &= ~0x80;
985 
986 	/* Skip input processing when we want to print it literally. */
987 	if (tp->t_flags & TF_LITERAL) {
988 		tp->t_flags &= ~TF_LITERAL;
989 		quote = 1;
990 		goto processed;
991 	}
992 
993 	/* Special control characters that are implementation dependent. */
994 	if (CMP_FLAG(l, IEXTEN)) {
995 		/* Accept the next character as literal. */
996 		if (CMP_CC(VLNEXT, c)) {
997 			if (CMP_FLAG(l, ECHO)) {
998 				if (CMP_FLAG(l, ECHOE))
999 					ttyoutq_write_nofrag(&tp->t_outq, "^\b", 2);
1000 				else
1001 					ttydisc_echo(tp, c, 0);
1002 			}
1003 			tp->t_flags |= TF_LITERAL;
1004 			return (0);
1005 		}
1006 		/* Discard processing */
1007 		if (CMP_CC(VDISCARD, c)) {
1008 			if (CMP_FLAG(l, FLUSHO)) {
1009 				tp->t_termios.c_lflag &= ~FLUSHO;
1010 			} else {
1011 				tty_flush(tp, FWRITE);
1012 				ttydisc_echo(tp, c, 0);
1013 				if (tp->t_inq.ti_end > 0)
1014 					ttydisc_reprint(tp);
1015 				tp->t_termios.c_lflag |= FLUSHO;
1016 			}
1017 		}
1018 	}
1019 
1020 	/*
1021 	 * Handle signal processing.
1022 	 */
1023 	if (CMP_FLAG(l, ISIG)) {
1024 		if (CMP_FLAG(l, ICANON|IEXTEN) == (ICANON|IEXTEN)) {
1025 			if (CMP_CC(VSTATUS, c)) {
1026 				tty_signal_pgrp(tp, SIGINFO);
1027 				return (0);
1028 			}
1029 		}
1030 
1031 		/*
1032 		 * When compared to the old implementation, this
1033 		 * implementation also flushes the output queue. POSIX
1034 		 * is really brief about this, but does makes us assume
1035 		 * we have to do so.
1036 		 */
1037 		signal = 0;
1038 		if (CMP_CC(VINTR, c)) {
1039 			signal = SIGINT;
1040 		} else if (CMP_CC(VQUIT, c)) {
1041 			signal = SIGQUIT;
1042 		} else if (CMP_CC(VSUSP, c)) {
1043 			signal = SIGTSTP;
1044 		}
1045 
1046 		if (signal != 0) {
1047 			/*
1048 			 * Echo the character before signalling the
1049 			 * processes.
1050 			 */
1051 			if (!CMP_FLAG(l, NOFLSH))
1052 				tty_flush(tp, FREAD|FWRITE);
1053 			ttydisc_echo(tp, c, 0);
1054 			tty_signal_pgrp(tp, signal);
1055 			return (0);
1056 		}
1057 	}
1058 
1059 	/*
1060 	 * Handle start/stop characters.
1061 	 */
1062 	if (CMP_FLAG(i, IXON)) {
1063 		if (CMP_CC(VSTOP, c)) {
1064 			/* Stop it if we aren't stopped yet. */
1065 			if ((tp->t_flags & TF_STOPPED) == 0) {
1066 				tp->t_flags |= TF_STOPPED;
1067 				return (0);
1068 			}
1069 			/*
1070 			 * Fallthrough:
1071 			 * When VSTART == VSTOP, we should make this key
1072 			 * toggle it.
1073 			 */
1074 			if (!CMP_CC(VSTART, c))
1075 				return (0);
1076 		}
1077 		if (CMP_CC(VSTART, c)) {
1078 			tp->t_flags &= ~TF_STOPPED;
1079 			return (0);
1080 		}
1081 	}
1082 
1083 	/* Conversion of CR and NL. */
1084 	switch (c) {
1085 	case CCR:
1086 		if (CMP_FLAG(i, IGNCR))
1087 			return (0);
1088 		if (CMP_FLAG(i, ICRNL))
1089 			c = CNL;
1090 		break;
1091 	case CNL:
1092 		if (CMP_FLAG(i, INLCR))
1093 			c = CCR;
1094 		break;
1095 	}
1096 
1097 	/* Canonical line editing. */
1098 	if (CMP_FLAG(l, ICANON)) {
1099 		if (CMP_CC(VERASE, c) || CMP_CC(VERASE2, c)) {
1100 			ttydisc_rubchar(tp);
1101 			return (0);
1102 		} else if (CMP_CC(VKILL, c)) {
1103 			while (ttydisc_rubchar(tp) == 0);
1104 			return (0);
1105 		} else if (CMP_FLAG(l, IEXTEN)) {
1106 			if (CMP_CC(VWERASE, c)) {
1107 				ttydisc_rubword(tp);
1108 				return (0);
1109 			} else if (CMP_CC(VREPRINT, c)) {
1110 				ttydisc_reprint(tp);
1111 				return (0);
1112 			}
1113 		}
1114 	}
1115 
1116 processed:
1117 	if (CMP_FLAG(i, PARMRK) && (unsigned char)c == 0xff) {
1118 		/* Print 0xff 0xff. */
1119 		ob[1] = 0xff;
1120 		ol = 2;
1121 		quote = 1;
1122 	} else {
1123 		ob[0] = c;
1124 		ol = 1;
1125 	}
1126 
1127 	goto print;
1128 
1129 parmrk:
1130 	if (CMP_FLAG(i, PARMRK)) {
1131 		/* Prepend 0xff 0x00 0x.. */
1132 		ob[2] = c;
1133 		ol = 3;
1134 		quote = 1;
1135 	} else {
1136 		ob[0] = c;
1137 		ol = 1;
1138 	}
1139 
1140 print:
1141 	/* See if we can store this on the input queue. */
1142 	if (ttyinq_write_nofrag(&tp->t_inq, ob, ol, quote) != 0) {
1143 		if (CMP_FLAG(i, IMAXBEL))
1144 			ttyoutq_write_nofrag(&tp->t_outq, "\a", 1);
1145 
1146 		/*
1147 		 * Prevent a deadlock here. It may be possible that a
1148 		 * user has entered so much data, there is no data
1149 		 * available to read(), but the buffers are full anyway.
1150 		 *
1151 		 * Only enter the high watermark if the device driver
1152 		 * can actually transmit something.
1153 		 */
1154 		if (ttyinq_bytescanonicalized(&tp->t_inq) == 0)
1155 			return (0);
1156 
1157 		tty_hiwat_in_block(tp);
1158 		return (-1);
1159 	}
1160 
1161 	/*
1162 	 * In raw mode, we canonicalize after receiving a single
1163 	 * character. Otherwise, we canonicalize when we receive a
1164 	 * newline, VEOL or VEOF, but only when it isn't quoted.
1165 	 */
1166 	if (!CMP_FLAG(l, ICANON) ||
1167 	    (!quote && (c == CNL || CMP_CC(VEOL, c) || CMP_CC(VEOF, c)))) {
1168 		ttyinq_canonicalize(&tp->t_inq);
1169 	}
1170 
1171 	ttydisc_echo(tp, c, quote);
1172 
1173 	return (0);
1174 }
1175 
1176 size_t
1177 ttydisc_rint_simple(struct tty *tp, const void *buf, size_t len)
1178 {
1179 	const char *cbuf;
1180 
1181 	if (ttydisc_can_bypass(tp))
1182 		return (ttydisc_rint_bypass(tp, buf, len));
1183 
1184 	for (cbuf = buf; len-- > 0; cbuf++) {
1185 		if (ttydisc_rint(tp, *cbuf, 0) != 0)
1186 			break;
1187 	}
1188 
1189 	return (cbuf - (const char *)buf);
1190 }
1191 
1192 size_t
1193 ttydisc_rint_bypass(struct tty *tp, const void *buf, size_t len)
1194 {
1195 	size_t ret;
1196 
1197 	tty_assert_locked(tp);
1198 
1199 	MPASS(tp->t_flags & TF_BYPASS);
1200 
1201 	atomic_add_long(&tty_nin, len);
1202 
1203 	if (ttyhook_hashook(tp, rint_bypass))
1204 		return ttyhook_rint_bypass(tp, buf, len);
1205 
1206 	ret = ttyinq_write(&tp->t_inq, buf, len, 0);
1207 	ttyinq_canonicalize(&tp->t_inq);
1208 	if (ret < len)
1209 		tty_hiwat_in_block(tp);
1210 
1211 	return (ret);
1212 }
1213 
1214 void
1215 ttydisc_rint_done(struct tty *tp)
1216 {
1217 
1218 	tty_assert_locked(tp);
1219 
1220 	if (ttyhook_hashook(tp, rint_done))
1221 		ttyhook_rint_done(tp);
1222 
1223 	/* Wake up readers. */
1224 	tty_wakeup(tp, FREAD);
1225 	/* Wake up driver for echo. */
1226 	ttydevsw_outwakeup(tp);
1227 }
1228 
1229 size_t
1230 ttydisc_rint_poll(struct tty *tp)
1231 {
1232 	size_t l;
1233 
1234 	tty_assert_locked(tp);
1235 
1236 	if (ttyhook_hashook(tp, rint_poll))
1237 		return ttyhook_rint_poll(tp);
1238 
1239 	/*
1240 	 * XXX: Still allow character input when there's no space in the
1241 	 * buffers, but we haven't entered the high watermark. This is
1242 	 * to allow backspace characters to be inserted when in
1243 	 * canonical mode.
1244 	 */
1245 	l = ttyinq_bytesleft(&tp->t_inq);
1246 	if (l == 0 && (tp->t_flags & TF_HIWAT_IN) == 0)
1247 		return (1);
1248 
1249 	return (l);
1250 }
1251 
1252 static void
1253 ttydisc_wakeup_watermark(struct tty *tp)
1254 {
1255 	size_t c;
1256 
1257 	c = ttyoutq_bytesleft(&tp->t_outq);
1258 	if (tp->t_flags & TF_HIWAT_OUT) {
1259 		/* Only allow us to run when we're below the watermark. */
1260 		if (c < tp->t_outlow)
1261 			return;
1262 
1263 		/* Reset the watermark. */
1264 		tp->t_flags &= ~TF_HIWAT_OUT;
1265 	} else {
1266 		/* Only run when we have data at all. */
1267 		if (c == 0)
1268 			return;
1269 	}
1270 	tty_wakeup(tp, FWRITE);
1271 }
1272 
1273 size_t
1274 ttydisc_getc(struct tty *tp, void *buf, size_t len)
1275 {
1276 
1277 	tty_assert_locked(tp);
1278 
1279 	if (tp->t_flags & TF_STOPPED)
1280 		return (0);
1281 
1282 	if (ttyhook_hashook(tp, getc_inject))
1283 		return ttyhook_getc_inject(tp, buf, len);
1284 
1285 	len = ttyoutq_read(&tp->t_outq, buf, len);
1286 
1287 	if (ttyhook_hashook(tp, getc_capture))
1288 		ttyhook_getc_capture(tp, buf, len);
1289 
1290 	ttydisc_wakeup_watermark(tp);
1291 	atomic_add_long(&tty_nout, len);
1292 
1293 	return (len);
1294 }
1295 
1296 int
1297 ttydisc_getc_uio(struct tty *tp, struct uio *uio)
1298 {
1299 	int error = 0;
1300 	ssize_t obytes = uio->uio_resid;
1301 	size_t len;
1302 	char buf[TTY_STACKBUF];
1303 
1304 	tty_assert_locked(tp);
1305 
1306 	if (tp->t_flags & TF_STOPPED)
1307 		return (0);
1308 
1309 	/*
1310 	 * When a TTY hook is attached, we cannot perform unbuffered
1311 	 * copying to userspace. Just call ttydisc_getc() and
1312 	 * temporarily store data in a shadow buffer.
1313 	 */
1314 	if (ttyhook_hashook(tp, getc_capture) ||
1315 	    ttyhook_hashook(tp, getc_inject)) {
1316 		while (uio->uio_resid > 0) {
1317 			/* Read to shadow buffer. */
1318 			len = ttydisc_getc(tp, buf,
1319 			    MIN(uio->uio_resid, sizeof buf));
1320 			if (len == 0)
1321 				break;
1322 
1323 			/* Copy to userspace. */
1324 			tty_unlock(tp);
1325 			error = uiomove(buf, len, uio);
1326 			tty_lock(tp);
1327 
1328 			if (error != 0)
1329 				break;
1330 		}
1331 	} else {
1332 		error = ttyoutq_read_uio(&tp->t_outq, tp, uio);
1333 
1334 		ttydisc_wakeup_watermark(tp);
1335 		atomic_add_long(&tty_nout, obytes - uio->uio_resid);
1336 	}
1337 
1338 	return (error);
1339 }
1340 
1341 size_t
1342 ttydisc_getc_poll(struct tty *tp)
1343 {
1344 
1345 	tty_assert_locked(tp);
1346 
1347 	if (tp->t_flags & TF_STOPPED)
1348 		return (0);
1349 
1350 	if (ttyhook_hashook(tp, getc_poll))
1351 		return ttyhook_getc_poll(tp);
1352 
1353 	return ttyoutq_bytesused(&tp->t_outq);
1354 }
1355 
1356 /*
1357  * XXX: not really related to the TTYDISC, but we'd better put
1358  * tty_putchar() here, because we need to perform proper output
1359  * processing.
1360  */
1361 
1362 int
1363 tty_putstrn(struct tty *tp, const char *p, size_t n)
1364 {
1365 	size_t i;
1366 
1367 	tty_assert_locked(tp);
1368 
1369 	if (tty_gone(tp))
1370 		return (-1);
1371 
1372 	for (i = 0; i < n; i++)
1373 		ttydisc_echo_force(tp, p[i], 0);
1374 
1375 	tp->t_writepos = tp->t_column;
1376 	ttyinq_reprintpos_set(&tp->t_inq);
1377 
1378 	ttydevsw_outwakeup(tp);
1379 	return (0);
1380 }
1381 
1382 int
1383 tty_putchar(struct tty *tp, char c)
1384 {
1385 	return (tty_putstrn(tp, &c, 1));
1386 }
1387