xref: /netbsd-src/sys/kern/tty.c (revision 001c68bd94f75ce9270b69227c4199fbf34ee396)
1 /*	$NetBSD: tty.c,v 1.154 2003/06/29 22:31:28 fvdl Exp $	*/
2 
3 /*-
4  * Copyright (c) 1982, 1986, 1990, 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  * (c) UNIX System Laboratories, Inc.
7  * All or some portions of this file are derived from material licensed
8  * to the University of California by American Telephone and Telegraph
9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10  * the permission of UNIX System Laboratories, Inc.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  *    must display the following acknowledgement:
22  *	This product includes software developed by the University of
23  *	California, Berkeley and its contributors.
24  * 4. Neither the name of the University nor the names of its contributors
25  *    may be used to endorse or promote products derived from this software
26  *    without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  *
40  *	@(#)tty.c	8.13 (Berkeley) 1/9/95
41  */
42 
43 #include <sys/cdefs.h>
44 __KERNEL_RCSID(0, "$NetBSD: tty.c,v 1.154 2003/06/29 22:31:28 fvdl Exp $");
45 
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/ioctl.h>
49 #include <sys/proc.h>
50 #define	TTYDEFCHARS
51 #include <sys/tty.h>
52 #undef	TTYDEFCHARS
53 #include <sys/file.h>
54 #include <sys/conf.h>
55 #include <sys/dkstat.h>
56 #include <sys/uio.h>
57 #include <sys/kernel.h>
58 #include <sys/vnode.h>
59 #include <sys/syslog.h>
60 #include <sys/malloc.h>
61 #include <sys/pool.h>
62 #include <sys/signalvar.h>
63 #include <sys/resourcevar.h>
64 #include <sys/poll.h>
65 #include <sys/kprintf.h>
66 #include <sys/namei.h>
67 
68 #include <machine/stdarg.h>
69 
70 static int	ttnread(struct tty *);
71 static void	ttyblock(struct tty *);
72 static void	ttyecho(int, struct tty *);
73 static void	ttyrubo(struct tty *, int);
74 static void	ttyprintf_nolock(struct tty *, const char *fmt, ...)
75     __attribute__((__format__(__printf__,2,3)));
76 static int	proc_compare(struct proc *, struct proc *);
77 
78 /* Symbolic sleep message strings. */
79 const char	ttclos[] = "ttycls";
80 const char	ttopen[] = "ttyopn";
81 const char	ttybg[] = "ttybg";
82 const char	ttyin[] = "ttyin";
83 const char	ttyout[] = "ttyout";
84 
85 /*
86  * Used to determine whether we still have a connection.  This is true in
87  * one of 3 cases:
88  * 1) We have carrier.
89  * 2) It's a locally attached terminal, and we are therefore ignoring carrier.
90  * 3) We're using a flow control mechanism that overloads the carrier signal.
91  */
92 #define	CONNECTED(tp)	(ISSET(tp->t_state, TS_CARR_ON) ||	\
93 			 ISSET(tp->t_cflag, CLOCAL | MDMBUF))
94 
95 /*
96  * Table with character classes and parity. The 8th bit indicates parity,
97  * the 7th bit indicates the character is an alphameric or underscore (for
98  * ALTWERASE), and the low 6 bits indicate delay type.  If the low 6 bits
99  * are 0 then the character needs no special processing on output; classes
100  * other than 0 might be translated or (not currently) require delays.
101  */
102 #define	E	0x00	/* Even parity. */
103 #define	O	0x80	/* Odd parity. */
104 #define	PARITY(c)	(char_type[c] & O)
105 
106 #define	ALPHA	0x40	/* Alpha or underscore. */
107 #define	ISALPHA(c)	(char_type[(c) & TTY_CHARMASK] & ALPHA)
108 
109 #define	CCLASSMASK	0x3f
110 #define	CCLASS(c)	(char_type[c] & CCLASSMASK)
111 
112 #define	BS	BACKSPACE
113 #define	CC	CONTROL
114 #define	CR	RETURN
115 #define	NA	ORDINARY | ALPHA
116 #define	NL	NEWLINE
117 #define	NO	ORDINARY
118 #define	TB	TAB
119 #define	VT	VTAB
120 
121 unsigned char const char_type[] = {
122 	E|CC, O|CC, O|CC, E|CC, O|CC, E|CC, E|CC, O|CC,	/* nul - bel */
123 	O|BS, E|TB, E|NL, O|CC, E|VT, O|CR, O|CC, E|CC,	/* bs - si */
124 	O|CC, E|CC, E|CC, O|CC, E|CC, O|CC, O|CC, E|CC,	/* dle - etb */
125 	E|CC, O|CC, O|CC, E|CC, O|CC, E|CC, E|CC, O|CC,	/* can - us */
126 	O|NO, E|NO, E|NO, O|NO, E|NO, O|NO, O|NO, E|NO,	/* sp - ' */
127 	E|NO, O|NO, O|NO, E|NO, O|NO, E|NO, E|NO, O|NO,	/* ( - / */
128 	E|NA, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA,	/* 0 - 7 */
129 	O|NA, E|NA, E|NO, O|NO, E|NO, O|NO, O|NO, E|NO,	/* 8 - ? */
130 	O|NO, E|NA, E|NA, O|NA, E|NA, O|NA, O|NA, E|NA,	/* @ - G */
131 	E|NA, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA,	/* H - O */
132 	E|NA, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA,	/* P - W */
133 	O|NA, E|NA, E|NA, O|NO, E|NO, O|NO, O|NO, O|NA,	/* X - _ */
134 	E|NO, O|NA, O|NA, E|NA, O|NA, E|NA, E|NA, O|NA,	/* ` - g */
135 	O|NA, E|NA, E|NA, O|NA, E|NA, O|NA, O|NA, E|NA,	/* h - o */
136 	O|NA, E|NA, E|NA, O|NA, E|NA, O|NA, O|NA, E|NA,	/* p - w */
137 	E|NA, O|NA, O|NA, E|NO, O|NO, E|NO, E|NO, O|CC,	/* x - del */
138 	/*
139 	 * Meta chars; should be settable per character set;
140 	 * for now, treat them all as normal characters.
141 	 */
142 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
143 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
144 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
145 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
146 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
147 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
148 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
149 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
150 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
151 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
152 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
153 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
154 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
155 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
156 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
157 	NA,   NA,   NA,   NA,   NA,   NA,   NA,   NA,
158 };
159 #undef	BS
160 #undef	CC
161 #undef	CR
162 #undef	NA
163 #undef	NL
164 #undef	NO
165 #undef	TB
166 #undef	VT
167 
168 /* Macros to clear/set/test flags. */
169 #define	SET(t, f)	(t) |= (f)
170 #define	CLR(t, f)	(t) &= ~((unsigned)(f))
171 #define	ISSET(t, f)	((t) & (f))
172 
173 struct simplelock ttylist_slock = SIMPLELOCK_INITIALIZER;
174 struct ttylist_head ttylist;	/* TAILQ_HEAD */
175 int tty_count;
176 
177 struct pool tty_pool;
178 
179 u_int64_t tk_cancc;
180 u_int64_t tk_nin;
181 u_int64_t tk_nout;
182 u_int64_t tk_rawcc;
183 
184 int
185 ttyopen(struct tty *tp, int dialout, int nonblock)
186 {
187 	int	s, error;
188 
189 	error = 0;
190 
191 	s = spltty();
192 	TTY_LOCK(tp);
193 
194 	if (dialout) {
195 		/*
196 		 * If the device is already open for non-dialout, fail.
197 		 * Otherwise, set TS_DIALOUT to block any pending non-dialout
198 		 * opens.
199 		 */
200 		if (ISSET(tp->t_state, TS_ISOPEN) &&
201 		    !ISSET(tp->t_state, TS_DIALOUT)) {
202 			error = EBUSY;
203 			goto out;
204 		}
205 		SET(tp->t_state, TS_DIALOUT);
206 	} else {
207 		if (!nonblock) {
208 			/*
209 			 * Wait for carrier.  Also wait for any dialout
210 			 * processes to close the tty first.
211 			 */
212 			while (ISSET(tp->t_state, TS_DIALOUT) ||
213 			       !CONNECTED(tp)) {
214 				tp->t_wopen++;
215 				error = ttysleep(tp, &tp->t_rawq,
216 				    TTIPRI | PCATCH, ttopen, 0);
217 				tp->t_wopen--;
218 				if (error)
219 					goto out;
220 			}
221 		} else {
222 			/*
223 			 * Don't allow a non-blocking non-dialout open if the
224 			 * device is already open for dialout.
225 			 */
226 			if (ISSET(tp->t_state, TS_DIALOUT)) {
227 				error = EBUSY;
228 				goto out;
229 			}
230 		}
231 	}
232 
233 out:
234 	TTY_UNLOCK(tp);
235 	splx(s);
236 	return (error);
237 }
238 
239 /*
240  * Initial open of tty, or (re)entry to standard tty line discipline.
241  */
242 int
243 ttylopen(dev_t device, struct tty *tp)
244 {
245 	int	s;
246 
247 	s = spltty();
248 	TTY_LOCK(tp);
249 	tp->t_dev = device;
250 	if (!ISSET(tp->t_state, TS_ISOPEN)) {
251 		SET(tp->t_state, TS_ISOPEN);
252 		memset(&tp->t_winsize, 0, sizeof(tp->t_winsize));
253 #ifdef COMPAT_OLDTTY
254 		tp->t_flags = 0;
255 #endif
256 	}
257 	TTY_UNLOCK(tp);
258 	splx(s);
259 	return (0);
260 }
261 
262 /*
263  * Handle close() on a tty line: flush and set to initial state,
264  * bumping generation number so that pending read/write calls
265  * can detect recycling of the tty.
266  */
267 int
268 ttyclose(struct tty *tp)
269 {
270 	extern struct tty *constty;	/* Temporary virtual console. */
271 	int s;
272 
273 	s = spltty();
274 	TTY_LOCK(tp);
275 
276 	if (constty == tp)
277 		constty = NULL;
278 
279 	ttyflush(tp, FREAD | FWRITE);
280 
281 	tp->t_gen++;
282 	tp->t_pgrp = NULL;
283 	if (tp->t_session != NULL) {
284 		SESSRELE(tp->t_session);
285 		tp->t_session = NULL;
286 	}
287 	tp->t_state = 0;
288 
289 	TTY_UNLOCK(tp);
290 	splx(s);
291 	return (0);
292 }
293 
294 #define	FLUSHQ(q) {							\
295 	if ((q)->c_cc)							\
296 		ndflush(q, (q)->c_cc);					\
297 }
298 
299 /*
300  * This macro is used in canonical mode input processing, where a read
301  * request shall not return unless a 'line delimiter' ('\n') or 'break'
302  * (EOF, EOL, EOL2) character (or a signal) has been received. As EOL2
303  * is an extension to the POSIX.1 defined set of special characters,
304  * recognize it only if IEXTEN is set in the set of local flags.
305  */
306 #define	TTBREAKC(c, lflg)						\
307 	((c) == '\n' || (((c) == cc[VEOF] || (c) == cc[VEOL] ||		\
308 	((c) == cc[VEOL2] && ISSET(lflg, IEXTEN))) && (c) != _POSIX_VDISABLE))
309 
310 
311 
312 /*
313  * ttyinput() helper.
314  * Call at spltty() and with the tty slock held.
315  */
316 static int
317 ttyinput_wlock(int c, struct tty *tp)
318 {
319 	const struct cdevsw *cdev;
320 	int	iflag, lflag, i, error;
321 	u_char	*cc;
322 
323 	/*
324 	 * If input is pending take it first.
325 	 */
326 	lflag = tp->t_lflag;
327 	if (ISSET(lflag, PENDIN))
328 		ttypend(tp);
329 	/*
330 	 * Gather stats.
331 	 */
332 	if (ISSET(lflag, ICANON)) {
333 		++tk_cancc;
334 		++tp->t_cancc;
335 	} else {
336 		++tk_rawcc;
337 		++tp->t_rawcc;
338 	}
339 	++tk_nin;
340 
341 	cc = tp->t_cc;
342 
343 	/*
344 	 * Handle exceptional conditions (break, parity, framing).
345 	 */
346 	iflag = tp->t_iflag;
347 	if ((error = (ISSET(c, TTY_ERRORMASK))) != 0) {
348 		CLR(c, TTY_ERRORMASK);
349 		if (ISSET(error, TTY_FE) && c == 0) {		/* Break. */
350 			if (ISSET(iflag, IGNBRK))
351 				return (0);
352 			else if (ISSET(iflag, BRKINT)) {
353 				ttyflush(tp, FREAD | FWRITE);
354 				pgsignal(tp->t_pgrp, SIGINT, 1);
355 				return (0);
356 			} else if (ISSET(iflag, PARMRK))
357 				goto parmrk;
358 		} else if ((ISSET(error, TTY_PE) && ISSET(iflag, INPCK)) ||
359 		    ISSET(error, TTY_FE)) {
360 			if (ISSET(iflag, IGNPAR))
361 				return (0);
362 			else if (ISSET(iflag, PARMRK)) {
363  parmrk:			(void)putc(0377 | TTY_QUOTE, &tp->t_rawq);
364 				(void)putc(0    | TTY_QUOTE, &tp->t_rawq);
365 				(void)putc(c    | TTY_QUOTE, &tp->t_rawq);
366 				return (0);
367 			} else
368 				c = 0;
369 		}
370 	} else if (c == 0377 &&
371 	    ISSET(iflag, ISTRIP|IGNPAR|INPCK|PARMRK) == (INPCK|PARMRK)) {
372 		/* "Escape" a valid character of '\377'. */
373 		(void)putc(0377 | TTY_QUOTE, &tp->t_rawq);
374 		(void)putc(0377 | TTY_QUOTE, &tp->t_rawq);
375 		goto endcase;
376 	}
377 
378 	/*
379 	 * In tandem mode, check high water mark.
380 	 */
381 	if (ISSET(iflag, IXOFF) || ISSET(tp->t_cflag, CHWFLOW))
382 		ttyblock(tp);
383 	if (!ISSET(tp->t_state, TS_TYPEN) && ISSET(iflag, ISTRIP))
384 		CLR(c, 0x80);
385 	if (!ISSET(lflag, EXTPROC)) {
386 		/*
387 		 * Check for literal nexting very first
388 		 */
389 		if (ISSET(tp->t_state, TS_LNCH)) {
390 			SET(c, TTY_QUOTE);
391 			CLR(tp->t_state, TS_LNCH);
392 		}
393 		/*
394 		 * Scan for special characters.  This code
395 		 * is really just a big case statement with
396 		 * non-constant cases.  The bottom of the
397 		 * case statement is labeled ``endcase'', so goto
398 		 * it after a case match, or similar.
399 		 */
400 
401 		/*
402 		 * Control chars which aren't controlled
403 		 * by ICANON, ISIG, or IXON.
404 		 */
405 		if (ISSET(lflag, IEXTEN)) {
406 			if (CCEQ(cc[VLNEXT], c)) {
407 				if (ISSET(lflag, ECHO)) {
408 					if (ISSET(lflag, ECHOE)) {
409 						(void)ttyoutput('^', tp);
410 						(void)ttyoutput('\b', tp);
411 					} else
412 						ttyecho(c, tp);
413 				}
414 				SET(tp->t_state, TS_LNCH);
415 				goto endcase;
416 			}
417 			if (CCEQ(cc[VDISCARD], c)) {
418 				if (ISSET(lflag, FLUSHO))
419 					CLR(tp->t_lflag, FLUSHO);
420 				else {
421 					ttyflush(tp, FWRITE);
422 					ttyecho(c, tp);
423 					if (tp->t_rawq.c_cc + tp->t_canq.c_cc)
424 						ttyretype(tp);
425 					SET(tp->t_lflag, FLUSHO);
426 				}
427 				goto startoutput;
428 			}
429 		}
430 		/*
431 		 * Signals.
432 		 */
433 		if (ISSET(lflag, ISIG)) {
434 			if (CCEQ(cc[VINTR], c) || CCEQ(cc[VQUIT], c)) {
435 				if (!ISSET(lflag, NOFLSH))
436 					ttyflush(tp, FREAD | FWRITE);
437 				ttyecho(c, tp);
438 				pgsignal(tp->t_pgrp,
439 				    CCEQ(cc[VINTR], c) ? SIGINT : SIGQUIT, 1);
440 				goto endcase;
441 			}
442 			if (CCEQ(cc[VSUSP], c)) {
443 				if (!ISSET(lflag, NOFLSH))
444 					ttyflush(tp, FREAD);
445 				ttyecho(c, tp);
446 				pgsignal(tp->t_pgrp, SIGTSTP, 1);
447 				goto endcase;
448 			}
449 		}
450 		/*
451 		 * Handle start/stop characters.
452 		 */
453 		if (ISSET(iflag, IXON)) {
454 			if (CCEQ(cc[VSTOP], c)) {
455 				if (!ISSET(tp->t_state, TS_TTSTOP)) {
456 					SET(tp->t_state, TS_TTSTOP);
457 					cdev = cdevsw_lookup(tp->t_dev);
458 					if (cdev != NULL)
459 						(*cdev->d_stop)(tp, 0);
460 					return (0);
461 				}
462 				if (!CCEQ(cc[VSTART], c))
463 					return (0);
464 				/*
465 				 * if VSTART == VSTOP then toggle
466 				 */
467 				goto endcase;
468 			}
469 			if (CCEQ(cc[VSTART], c))
470 				goto restartoutput;
471 		}
472 		/*
473 		 * IGNCR, ICRNL, & INLCR
474 		 */
475 		if (c == '\r') {
476 			if (ISSET(iflag, IGNCR))
477 				goto endcase;
478 			else if (ISSET(iflag, ICRNL))
479 				c = '\n';
480 		} else if (c == '\n' && ISSET(iflag, INLCR))
481 			c = '\r';
482 	}
483 	if (!ISSET(lflag, EXTPROC) && ISSET(lflag, ICANON)) {
484 		/*
485 		 * From here on down canonical mode character
486 		 * processing takes place.
487 		 */
488 		/*
489 		 * erase (^H / ^?)
490 		 */
491 		if (CCEQ(cc[VERASE], c)) {
492 			if (tp->t_rawq.c_cc)
493 				ttyrub(unputc(&tp->t_rawq), tp);
494 			goto endcase;
495 		}
496 		/*
497 		 * kill (^U)
498 		 */
499 		if (CCEQ(cc[VKILL], c)) {
500 			if (ISSET(lflag, ECHOKE) &&
501 			    tp->t_rawq.c_cc == tp->t_rocount &&
502 			    !ISSET(lflag, ECHOPRT))
503 				while (tp->t_rawq.c_cc)
504 					ttyrub(unputc(&tp->t_rawq), tp);
505 			else {
506 				ttyecho(c, tp);
507 				if (ISSET(lflag, ECHOK) ||
508 				    ISSET(lflag, ECHOKE))
509 					ttyecho('\n', tp);
510 				FLUSHQ(&tp->t_rawq);
511 				tp->t_rocount = 0;
512 			}
513 			CLR(tp->t_state, TS_LOCAL);
514 			goto endcase;
515 		}
516 		/*
517 		 * Extensions to the POSIX.1 GTI set of functions.
518 		 */
519 		if (ISSET(lflag, IEXTEN)) {
520 			/*
521 			 * word erase (^W)
522 			 */
523 			if (CCEQ(cc[VWERASE], c)) {
524 				int alt = ISSET(lflag, ALTWERASE);
525 				int ctype;
526 
527 				/*
528 				 * erase whitespace
529 				 */
530 				while ((c = unputc(&tp->t_rawq)) == ' ' ||
531 				    c == '\t')
532 					ttyrub(c, tp);
533 				if (c == -1)
534 					goto endcase;
535 				/*
536 				 * erase last char of word and remember the
537 				 * next chars type (for ALTWERASE)
538 				 */
539 				ttyrub(c, tp);
540 				c = unputc(&tp->t_rawq);
541 				if (c == -1)
542 					goto endcase;
543 				if (c == ' ' || c == '\t') {
544 					(void)putc(c, &tp->t_rawq);
545 					goto endcase;
546 				}
547 				ctype = ISALPHA(c);
548 				/*
549 				 * erase rest of word
550 				 */
551 				do {
552 					ttyrub(c, tp);
553 					c = unputc(&tp->t_rawq);
554 					if (c == -1)
555 						goto endcase;
556 				} while (c != ' ' && c != '\t' &&
557 				    (alt == 0 || ISALPHA(c) == ctype));
558 				(void)putc(c, &tp->t_rawq);
559 				goto endcase;
560 			}
561 			/*
562 			 * reprint line (^R)
563 			 */
564 			if (CCEQ(cc[VREPRINT], c)) {
565 				ttyretype(tp);
566 				goto endcase;
567 			}
568 			/*
569 			 * ^T - kernel info and generate SIGINFO
570 			 */
571 			if (CCEQ(cc[VSTATUS], c)) {
572 				if (!ISSET(lflag, NOKERNINFO))
573 					ttyinfo(tp);
574 				if (ISSET(lflag, ISIG))
575 					pgsignal(tp->t_pgrp, SIGINFO, 1);
576 				goto endcase;
577 			}
578 		}
579 	}
580 	/*
581 	 * Check for input buffer overflow
582 	 */
583 	if (tp->t_rawq.c_cc + tp->t_canq.c_cc >= TTYHOG) {
584 		if (ISSET(iflag, IMAXBEL)) {
585 			if (tp->t_outq.c_cc < tp->t_hiwat)
586 				(void)ttyoutput(CTRL('g'), tp);
587 		} else
588 			ttyflush(tp, FREAD | FWRITE);
589 		goto endcase;
590 	}
591 	/*
592 	 * Put data char in q for user and
593 	 * wakeup on seeing a line delimiter.
594 	 */
595 	if (putc(c, &tp->t_rawq) >= 0) {
596 		if (!ISSET(lflag, ICANON)) {
597 			ttwakeup(tp);
598 			ttyecho(c, tp);
599 			goto endcase;
600 		}
601 		if (TTBREAKC(c, lflag)) {
602 			tp->t_rocount = 0;
603 			catq(&tp->t_rawq, &tp->t_canq);
604 			ttwakeup(tp);
605 		} else if (tp->t_rocount++ == 0)
606 			tp->t_rocol = tp->t_column;
607 		if (ISSET(tp->t_state, TS_ERASE)) {
608 			/*
609 			 * end of prterase \.../
610 			 */
611 			CLR(tp->t_state, TS_ERASE);
612 			(void)ttyoutput('/', tp);
613 		}
614 		i = tp->t_column;
615 		ttyecho(c, tp);
616 		if (CCEQ(cc[VEOF], c) && ISSET(lflag, ECHO)) {
617 			/*
618 			 * Place the cursor over the '^' of the ^D.
619 			 */
620 			i = min(2, tp->t_column - i);
621 			while (i > 0) {
622 				(void)ttyoutput('\b', tp);
623 				i--;
624 			}
625 		}
626 	}
627  endcase:
628 	/*
629 	 * IXANY means allow any character to restart output.
630 	 */
631 	if (ISSET(tp->t_state, TS_TTSTOP) &&
632 	    !ISSET(iflag, IXANY) && cc[VSTART] != cc[VSTOP]) {
633 		return (0);
634 	}
635  restartoutput:
636 	CLR(tp->t_lflag, FLUSHO);
637 	CLR(tp->t_state, TS_TTSTOP);
638  startoutput:
639 	return (ttstart(tp));
640 }
641 
642 /*
643  * Process input of a single character received on a tty.
644  * Must be called at spltty().
645  *
646  * XXX - this is a hack, all drivers must changed to acquire the
647  *	 lock before calling linesw->l_rint()
648  */
649 int
650 ttyinput(int c, struct tty *tp)
651 {
652 	int error;
653 
654 	/*
655 	 * Unless the receiver is enabled, drop incoming data.
656 	 */
657 	if (!ISSET(tp->t_cflag, CREAD))
658 		return (0);
659 
660 	TTY_LOCK(tp);
661 	error = ttyinput_wlock(c, tp);
662 	TTY_UNLOCK(tp);
663 	return (error);
664 }
665 
666 /*
667  * Output a single character on a tty, doing output processing
668  * as needed (expanding tabs, newline processing, etc.).
669  * Returns < 0 if succeeds, otherwise returns char to resend.
670  * Must be recursive.
671  * Call with tty slock held.
672  */
673 int
674 ttyoutput(int c, struct tty *tp)
675 {
676 	long	oflag;
677 	int	col, notout, s;
678 
679 	oflag = tp->t_oflag;
680 	if (!ISSET(oflag, OPOST)) {
681 		tk_nout++;
682 		tp->t_outcc++;
683 		if (!ISSET(tp->t_lflag, FLUSHO) && putc(c, &tp->t_outq))
684 			return (c);
685 		return (-1);
686 	}
687 	/*
688 	 * Do tab expansion if OXTABS is set.  Special case if we do external
689 	 * processing, we don't do the tab expansion because we'll probably
690 	 * get it wrong.  If tab expansion needs to be done, let it happen
691 	 * externally.
692 	 */
693 	CLR(c, ~TTY_CHARMASK);
694 	if (c == '\t' &&
695 	    ISSET(oflag, OXTABS) && !ISSET(tp->t_lflag, EXTPROC)) {
696 		c = 8 - (tp->t_column & 7);
697 		if (ISSET(tp->t_lflag, FLUSHO)) {
698 			notout = 0;
699 		} else {
700 			s = spltty();		/* Don't interrupt tabs. */
701 			notout = b_to_q("        ", c, &tp->t_outq);
702 			c -= notout;
703 			tk_nout += c;
704 			tp->t_outcc += c;
705 			splx(s);
706 		}
707 		tp->t_column += c;
708 		return (notout ? '\t' : -1);
709 	}
710 	if (c == CEOT && ISSET(oflag, ONOEOT))
711 		return (-1);
712 
713 	/*
714 	 * Newline translation: if ONLCR is set,
715 	 * translate newline into "\r\n".
716 	 */
717 	if (c == '\n' && ISSET(tp->t_oflag, ONLCR)) {
718 		tk_nout++;
719 		tp->t_outcc++;
720 		if (!ISSET(tp->t_lflag, FLUSHO) && putc('\r', &tp->t_outq))
721 			return (c);
722 	}
723 	/* If OCRNL is set, translate "\r" into "\n". */
724 	else if (c == '\r' && ISSET(tp->t_oflag, OCRNL))
725 		c = '\n';
726 	/* If ONOCR is set, don't transmit CRs when on column 0. */
727 	else if (c == '\r' && ISSET(tp->t_oflag, ONOCR) && tp->t_column == 0)
728 		return (-1);
729 
730 	tk_nout++;
731 	tp->t_outcc++;
732 	if (!ISSET(tp->t_lflag, FLUSHO) && putc(c, &tp->t_outq))
733 		return (c);
734 
735 	col = tp->t_column;
736 	switch (CCLASS(c)) {
737 	case BACKSPACE:
738 		if (col > 0)
739 			--col;
740 		break;
741 	case CONTROL:
742 		break;
743 	case NEWLINE:
744 		if (ISSET(tp->t_oflag, ONLCR | ONLRET))
745 			col = 0;
746 		break;
747 	case RETURN:
748 		col = 0;
749 		break;
750 	case ORDINARY:
751 		++col;
752 		break;
753 	case TAB:
754 		col = (col + 8) & ~7;
755 		break;
756 	}
757 	tp->t_column = col;
758 	return (-1);
759 }
760 
761 /*
762  * Ioctls for all tty devices.  Called after line-discipline specific ioctl
763  * has been called to do discipline-specific functions and/or reject any
764  * of these ioctl commands.
765  */
766 /* ARGSUSED */
767 int
768 ttioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct proc *p)
769 {
770 	extern struct tty *constty;	/* Temporary virtual console. */
771 	struct linesw	*lp;
772 	int		s, error;
773 	struct nameidata nd;
774 
775 	/* If the ioctl involves modification, hang if in the background. */
776 	switch (cmd) {
777 	case  TIOCFLUSH:
778 	case  TIOCDRAIN:
779 	case  TIOCSBRK:
780 	case  TIOCCBRK:
781 	case  TIOCSTART:
782 	case  TIOCSETA:
783 	case  TIOCSETD:
784 	case  TIOCSLINED:
785 	case  TIOCSETAF:
786 	case  TIOCSETAW:
787 #ifdef notdef
788 	case  TIOCSPGRP:
789 #endif
790 	case  TIOCSTAT:
791 	case  TIOCSTI:
792 	case  TIOCSWINSZ:
793 #ifdef COMPAT_OLDTTY
794 	case  TIOCLBIC:
795 	case  TIOCLBIS:
796 	case  TIOCLSET:
797 	case  TIOCSETC:
798 	case OTIOCSETD:
799 	case  TIOCSETN:
800 	case  TIOCSETP:
801 	case  TIOCSLTC:
802 #endif
803 		while (isbackground(curproc, tp) &&
804 		    p->p_pgrp->pg_jobc && (p->p_flag & P_PPWAIT) == 0 &&
805 		    !sigismasked(p, SIGTTOU)) {
806 			pgsignal(p->p_pgrp, SIGTTOU, 1);
807 			s = spltty();
808 			TTY_LOCK(tp);
809 			error = ttysleep(tp, &lbolt,
810 					 TTOPRI | PCATCH | PNORELOCK, ttybg, 0);
811 			splx(s);
812 			if (error) {
813 				return (error);
814 			}
815 		}
816 		break;
817 	}
818 
819 	switch (cmd) {			/* Process the ioctl. */
820 	case FIOASYNC:			/* set/clear async i/o */
821 		s = spltty();
822 		TTY_LOCK(tp);
823 		if (*(int *)data)
824 			SET(tp->t_state, TS_ASYNC);
825 		else
826 			CLR(tp->t_state, TS_ASYNC);
827 		TTY_UNLOCK(tp);
828 		splx(s);
829 		break;
830 	case FIONBIO:			/* set/clear non-blocking i/o */
831 		break;			/* XXX: delete. */
832 	case FIONREAD:			/* get # bytes to read */
833 		s = spltty();
834 		TTY_LOCK(tp);
835 		*(int *)data = ttnread(tp);
836 		TTY_UNLOCK(tp);
837 		splx(s);
838 		break;
839 	case TIOCEXCL:			/* set exclusive use of tty */
840 		s = spltty();
841 		TTY_LOCK(tp);
842 		SET(tp->t_state, TS_XCLUDE);
843 		splx(s);
844 		TTY_UNLOCK(tp);
845 		break;
846 	case TIOCFLUSH: {		/* flush buffers */
847 		int flags = *(int *)data;
848 
849 		if (flags == 0)
850 			flags = FREAD | FWRITE;
851 		else
852 			flags &= FREAD | FWRITE;
853 		s = spltty();
854 		TTY_LOCK(tp);
855 		ttyflush(tp, flags);
856 		TTY_UNLOCK(tp);
857 		splx(s);
858 		break;
859 	}
860 	case TIOCCONS:			/* become virtual console */
861 		if (*(int *)data) {
862 			if (constty && constty != tp &&
863 			    ISSET(constty->t_state, TS_CARR_ON | TS_ISOPEN) ==
864 			    (TS_CARR_ON | TS_ISOPEN))
865 				return EBUSY;
866 
867 			NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
868 			    "/dev/console", p);
869 			if ((error = namei(&nd)) != 0)
870 				return error;
871 			error = VOP_ACCESS(nd.ni_vp, VREAD, p->p_ucred, p);
872 			vput(nd.ni_vp);
873 			if (error)
874 				return error;
875 
876 			constty = tp;
877 		} else if (tp == constty)
878 			constty = NULL;
879 		break;
880 	case TIOCDRAIN:			/* wait till output drained */
881 		if ((error = ttywait(tp)) != 0)
882 			return (error);
883 		break;
884 	case TIOCGETA: {		/* get termios struct */
885 		struct termios *t = (struct termios *)data;
886 
887 		memcpy(t, &tp->t_termios, sizeof(struct termios));
888 		break;
889 	}
890 	case TIOCGETD:			/* get line discipline */
891 		*(int *)data = tp->t_linesw->l_no;
892 		break;
893 	case TIOCGLINED:
894 		(void)strncpy((char *)data, tp->t_linesw->l_name,
895 		    TTLINEDNAMELEN - 1);
896 		break;
897 	case TIOCGWINSZ:		/* get window size */
898 		*(struct winsize *)data = tp->t_winsize;
899 		break;
900 	case TIOCGPGRP:			/* get pgrp of tty */
901 		if (!isctty(p, tp))
902 			return (ENOTTY);
903 		*(int *)data = tp->t_pgrp ? tp->t_pgrp->pg_id : NO_PGID;
904 		break;
905 	case TIOCGSID:			/* get sid of tty */
906 		if (!isctty(p, tp))
907 			return (ENOTTY);
908 		*(int *)data = tp->t_session->s_sid;
909 		break;
910 #ifdef TIOCHPCL
911 	case TIOCHPCL:			/* hang up on last close */
912 		s = spltty();
913 		TTY_LOCK(tp);
914 		SET(tp->t_cflag, HUPCL);
915 		TTY_UNLOCK(tp);
916 		splx(s);
917 		break;
918 #endif
919 	case TIOCNXCL:			/* reset exclusive use of tty */
920 		s = spltty();
921 		TTY_LOCK(tp);
922 		CLR(tp->t_state, TS_XCLUDE);
923 		TTY_UNLOCK(tp);
924 		splx(s);
925 		break;
926 	case TIOCOUTQ:			/* output queue size */
927 		*(int *)data = tp->t_outq.c_cc;
928 		break;
929 	case TIOCSETA:			/* set termios struct */
930 	case TIOCSETAW:			/* drain output, set */
931 	case TIOCSETAF: {		/* drn out, fls in, set */
932 		struct termios *t = (struct termios *)data;
933 
934 		if (cmd == TIOCSETAW || cmd == TIOCSETAF) {
935 			if ((error = ttywait(tp)) != 0)
936 				return (error);
937 
938 			if (cmd == TIOCSETAF) {
939 				s = spltty();
940 				TTY_LOCK(tp);
941 				ttyflush(tp, FREAD);
942 				TTY_UNLOCK(tp);
943 				splx(s);
944 			}
945 		}
946 
947 		s = spltty();
948 		/*
949 		 * XXXSMP - some drivers call back on us from t_param(), so
950 		 *	    don't take the tty spin lock here.
951 		 *	    require t_param() to unlock upon callback?
952 		 */
953 		/* wanted here: TTY_LOCK(tp); */
954 		if (!ISSET(t->c_cflag, CIGNORE)) {
955 			/*
956 			 * Set device hardware.
957 			 */
958 			if (tp->t_param && (error = (*tp->t_param)(tp, t))) {
959 				/* wanted here: TTY_UNLOCK(tp); */
960 				splx(s);
961 				return (error);
962 			} else {
963 				tp->t_cflag = t->c_cflag;
964 				tp->t_ispeed = t->c_ispeed;
965 				tp->t_ospeed = t->c_ospeed;
966 				if (t->c_ospeed == 0 && tp->t_session &&
967 				    tp->t_session->s_leader)
968 					psignal(tp->t_session->s_leader,
969 					    SIGHUP);
970 			}
971 			ttsetwater(tp);
972 		}
973 
974 		/* delayed lock acquiring */TTY_LOCK(tp);
975 		if (cmd != TIOCSETAF) {
976 			if (ISSET(t->c_lflag, ICANON) !=
977 			    ISSET(tp->t_lflag, ICANON)) {
978 				if (ISSET(t->c_lflag, ICANON)) {
979 					SET(tp->t_lflag, PENDIN);
980 					ttwakeup(tp);
981 				} else {
982 					struct clist tq;
983 
984 					catq(&tp->t_rawq, &tp->t_canq);
985 					tq = tp->t_rawq;
986 					tp->t_rawq = tp->t_canq;
987 					tp->t_canq = tq;
988 					CLR(tp->t_lflag, PENDIN);
989 				}
990 			}
991 		}
992 		tp->t_iflag = t->c_iflag;
993 		tp->t_oflag = t->c_oflag;
994 		/*
995 		 * Make the EXTPROC bit read only.
996 		 */
997 		if (ISSET(tp->t_lflag, EXTPROC))
998 			SET(t->c_lflag, EXTPROC);
999 		else
1000 			CLR(t->c_lflag, EXTPROC);
1001 		tp->t_lflag = t->c_lflag | ISSET(tp->t_lflag, PENDIN);
1002 		memcpy(tp->t_cc, t->c_cc, sizeof(t->c_cc));
1003 		TTY_UNLOCK(tp);
1004 		splx(s);
1005 		break;
1006 	}
1007 	case TIOCSETD: {		/* set line discipline */
1008 		int t = *(int *)data;
1009 
1010 		if (t < 0)
1011 			return (EINVAL);
1012 		if (t >= nlinesw)
1013 			return (ENXIO);
1014 		lp = linesw[t];
1015 		goto setldisc;
1016 	}
1017 	case TIOCSLINED: {		/* set line discipline */
1018 		char *name = (char *)data;
1019 		dev_t device;
1020 
1021 		/* Null terminate to prevent buffer overflow */
1022 		name[TTLINEDNAMELEN - 1] = '\0';
1023 		lp = ttyldisc_lookup(name);
1024 
1025  setldisc:
1026 		if (lp == NULL)
1027 			return (ENXIO);
1028 
1029 		if (lp != tp->t_linesw) {
1030 			device = tp->t_dev;
1031 			s = spltty();
1032 			(*tp->t_linesw->l_close)(tp, flag);
1033 			error = (*lp->l_open)(device, tp);
1034 			if (error) {
1035 				(void)(*tp->t_linesw->l_open)(device, tp);
1036 				splx(s);
1037 				return (error);
1038 			}
1039 			tp->t_linesw = lp;
1040 			splx(s);
1041 		}
1042 		break;
1043 	}
1044 	case TIOCSTART:			/* start output, like ^Q */
1045 		s = spltty();
1046 		TTY_LOCK(tp);
1047 		if (ISSET(tp->t_state, TS_TTSTOP) ||
1048 		    ISSET(tp->t_lflag, FLUSHO)) {
1049 			CLR(tp->t_lflag, FLUSHO);
1050 			CLR(tp->t_state, TS_TTSTOP);
1051 			ttstart(tp);
1052 		}
1053 		TTY_UNLOCK(tp);
1054 		splx(s);
1055 		break;
1056 	case TIOCSTI:			/* simulate terminal input */
1057 		if (p->p_ucred->cr_uid && (flag & FREAD) == 0)
1058 			return (EPERM);
1059 		if (p->p_ucred->cr_uid && !isctty(p, tp))
1060 			return (EACCES);
1061 		(*tp->t_linesw->l_rint)(*(u_char *)data, tp);
1062 		break;
1063 	case TIOCSTOP:			/* stop output, like ^S */
1064 	{
1065 		const struct cdevsw *cdev;
1066 		s = spltty();
1067 		TTY_LOCK(tp);
1068 		if (!ISSET(tp->t_state, TS_TTSTOP)) {
1069 			SET(tp->t_state, TS_TTSTOP);
1070 			cdev = cdevsw_lookup(tp->t_dev);
1071 			if (cdev != NULL)
1072 				(*cdev->d_stop)(tp, 0);
1073 		}
1074 		TTY_UNLOCK(tp);
1075 		splx(s);
1076 		break;
1077 	}
1078 	case TIOCSCTTY:			/* become controlling tty */
1079 		/* Session ctty vnode pointer set in vnode layer. */
1080 		if (!SESS_LEADER(p) ||
1081 		    ((p->p_session->s_ttyvp || tp->t_session) &&
1082 		    (tp->t_session != p->p_session)))
1083 			return (EPERM);
1084 
1085 		if (tp->t_session)
1086 			SESSRELE(tp->t_session);
1087 
1088 		SESSHOLD(p->p_session);
1089 		tp->t_session = p->p_session;
1090 		tp->t_pgrp = p->p_pgrp;
1091 		p->p_session->s_ttyp = tp;
1092 		p->p_flag |= P_CONTROLT;
1093 		break;
1094 	case TIOCSPGRP: {		/* set pgrp of tty */
1095 		struct pgrp *pgrp = pgfind(*(int *)data);
1096 
1097 		if (!isctty(p, tp))
1098 			return (ENOTTY);
1099 		else if (pgrp == NULL)
1100 			return (EINVAL);
1101 		else if (pgrp->pg_session != p->p_session)
1102 			return (EPERM);
1103 		tp->t_pgrp = pgrp;
1104 		break;
1105 	}
1106 	case TIOCSTAT:			/* get load avg stats */
1107 		TTY_LOCK(tp);
1108 		ttyinfo(tp);
1109 		TTY_UNLOCK(tp);
1110 		break;
1111 	case TIOCSWINSZ:		/* set window size */
1112 		if (memcmp((caddr_t)&tp->t_winsize, data,
1113 		    sizeof(struct winsize))) {
1114 			tp->t_winsize = *(struct winsize *)data;
1115 			pgsignal(tp->t_pgrp, SIGWINCH, 1);
1116 		}
1117 		break;
1118 	default:
1119 #ifdef COMPAT_OLDTTY
1120 		return (ttcompat(tp, cmd, data, flag, p));
1121 #else
1122 		return (EPASSTHROUGH);
1123 #endif
1124 	}
1125 	return (0);
1126 }
1127 
1128 int
1129 ttpoll(struct tty *tp, int events, struct proc *p)
1130 {
1131 	int	revents, s;
1132 
1133 	revents = 0;
1134 	s = spltty();
1135 	TTY_LOCK(tp);
1136 	if (events & (POLLIN | POLLRDNORM))
1137 		if (ttnread(tp) > 0)
1138 			revents |= events & (POLLIN | POLLRDNORM);
1139 
1140 	if (events & (POLLOUT | POLLWRNORM))
1141 		if (tp->t_outq.c_cc <= tp->t_lowat)
1142 			revents |= events & (POLLOUT | POLLWRNORM);
1143 
1144 	if (events & POLLHUP)
1145 		if (!CONNECTED(tp))
1146 			revents |= POLLHUP;
1147 
1148 	if (revents == 0) {
1149 		if (events & (POLLIN | POLLHUP | POLLRDNORM))
1150 			selrecord(p, &tp->t_rsel);
1151 
1152 		if (events & (POLLOUT | POLLWRNORM))
1153 			selrecord(p, &tp->t_wsel);
1154 	}
1155 
1156 	TTY_UNLOCK(tp);
1157 	splx(s);
1158 	return (revents);
1159 }
1160 
1161 static void
1162 filt_ttyrdetach(struct knote *kn)
1163 {
1164 	struct tty	*tp;
1165 	int		s;
1166 
1167 	tp = kn->kn_hook;
1168 	s = spltty();
1169 	SLIST_REMOVE(&tp->t_rsel.sel_klist, kn, knote, kn_selnext);
1170 	splx(s);
1171 }
1172 
1173 static int
1174 filt_ttyread(struct knote *kn, long hint)
1175 {
1176 	struct tty	*tp;
1177 	int		s;
1178 
1179 	tp = kn->kn_hook;
1180 	s = spltty();
1181 	TTY_LOCK(tp);
1182 	kn->kn_data = ttnread(tp);
1183 	TTY_UNLOCK(tp);
1184 	splx(s);
1185 	return (kn->kn_data > 0);
1186 }
1187 
1188 static void
1189 filt_ttywdetach(struct knote *kn)
1190 {
1191 	struct tty	*tp;
1192 	int		s;
1193 
1194 	tp = kn->kn_hook;
1195 	s = spltty();
1196 	TTY_LOCK(tp);
1197 	SLIST_REMOVE(&tp->t_wsel.sel_klist, kn, knote, kn_selnext);
1198 	TTY_UNLOCK(tp);
1199 	splx(s);
1200 }
1201 
1202 static int
1203 filt_ttywrite(struct knote *kn, long hint)
1204 {
1205 	struct tty	*tp;
1206 	int		canwrite, s;
1207 
1208 	tp = kn->kn_hook;
1209 	s = spltty();
1210 	TTY_LOCK(tp);
1211 	kn->kn_data = tp->t_outq.c_cn - tp->t_outq.c_cc;
1212 	canwrite = (tp->t_outq.c_cc <= tp->t_lowat) && CONNECTED(tp);
1213 	TTY_UNLOCK(tp);
1214 	splx(s);
1215 	return (canwrite);
1216 }
1217 
1218 static const struct filterops ttyread_filtops =
1219 	{ 1, NULL, filt_ttyrdetach, filt_ttyread };
1220 static const struct filterops ttywrite_filtops =
1221 	{ 1, NULL, filt_ttywdetach, filt_ttywrite };
1222 
1223 int
1224 ttykqfilter(dev_t dev, struct knote *kn)
1225 {
1226 	struct tty	*tp;
1227 	struct klist	*klist;
1228 	int		s;
1229 	const struct cdevsw	*cdev;
1230 
1231 	cdev = cdevsw_lookup(dev);
1232 	if (cdev == NULL)
1233 		return (ENXIO);
1234 	tp = (*cdev->d_tty)(dev);
1235 	switch (kn->kn_filter) {
1236 	case EVFILT_READ:
1237 		klist = &tp->t_rsel.sel_klist;
1238 		kn->kn_fop = &ttyread_filtops;
1239 		break;
1240 	case EVFILT_WRITE:
1241 		klist = &tp->t_wsel.sel_klist;
1242 		kn->kn_fop = &ttywrite_filtops;
1243 		break;
1244 	default:
1245 		return (1);
1246 	}
1247 
1248 	kn->kn_hook = tp;
1249 
1250 	s = spltty();
1251 	TTY_LOCK(tp);
1252 	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
1253 	TTY_UNLOCK(tp);
1254 	splx(s);
1255 
1256 	return (0);
1257 }
1258 
1259 /*
1260  * Find the number of chars ready to be read from this tty.
1261  * Call at spltty() and with the tty slock held.
1262  */
1263 static int
1264 ttnread(struct tty *tp)
1265 {
1266 	int	nread;
1267 
1268 	if (ISSET(tp->t_lflag, PENDIN))
1269 		ttypend(tp);
1270 	nread = tp->t_canq.c_cc;
1271 	if (!ISSET(tp->t_lflag, ICANON)) {
1272 		nread += tp->t_rawq.c_cc;
1273 		if (nread < tp->t_cc[VMIN] && !tp->t_cc[VTIME])
1274 			nread = 0;
1275 	}
1276 	return (nread);
1277 }
1278 
1279 /*
1280  * Wait for output to drain.
1281  */
1282 int
1283 ttywait(struct tty *tp)
1284 {
1285 	int	error, s;
1286 
1287 	error = 0;
1288 	s = spltty();
1289 	TTY_LOCK(tp);
1290 	while ((tp->t_outq.c_cc || ISSET(tp->t_state, TS_BUSY)) &&
1291 	    CONNECTED(tp) && tp->t_oproc) {
1292 		(*tp->t_oproc)(tp);
1293 		SET(tp->t_state, TS_ASLEEP);
1294 		error = ttysleep(tp, &tp->t_outq, TTOPRI | PCATCH, ttyout, 0);
1295 		if (error)
1296 			break;
1297 	}
1298 	TTY_UNLOCK(tp);
1299 	splx(s);
1300 	return (error);
1301 }
1302 
1303 /*
1304  * Flush if successfully wait.
1305  */
1306 int
1307 ttywflush(struct tty *tp)
1308 {
1309 	int	error;
1310 	int	s;
1311 
1312 	if ((error = ttywait(tp)) == 0) {
1313 		s = spltty();
1314 		TTY_LOCK(tp);
1315 		ttyflush(tp, FREAD);
1316 		TTY_UNLOCK(tp);
1317 		splx(s);
1318 	}
1319 	return (error);
1320 }
1321 
1322 /*
1323  * Flush tty read and/or write queues, notifying anyone waiting.
1324  * Call at spltty() and with the tty slock held.
1325  */
1326 void
1327 ttyflush(struct tty *tp, int rw)
1328 {
1329 	const struct cdevsw *cdev;
1330 
1331 	if (rw & FREAD) {
1332 		FLUSHQ(&tp->t_canq);
1333 		FLUSHQ(&tp->t_rawq);
1334 		tp->t_rocount = 0;
1335 		tp->t_rocol = 0;
1336 		CLR(tp->t_state, TS_LOCAL);
1337 		ttwakeup(tp);
1338 	}
1339 	if (rw & FWRITE) {
1340 		CLR(tp->t_state, TS_TTSTOP);
1341 		cdev = cdevsw_lookup(tp->t_dev);
1342 		if (cdev != NULL)
1343 			(*cdev->d_stop)(tp, rw);
1344 		FLUSHQ(&tp->t_outq);
1345 		wakeup((caddr_t)&tp->t_outq);
1346 		selnotify(&tp->t_wsel, 0);
1347 	}
1348 }
1349 
1350 /*
1351  * Copy in the default termios characters.
1352  */
1353 void
1354 ttychars(struct tty *tp)
1355 {
1356 
1357 	memcpy(tp->t_cc, ttydefchars, sizeof(ttydefchars));
1358 }
1359 
1360 /*
1361  * Send stop character on input overflow.
1362  * Call at spltty() and with the tty slock held.
1363  */
1364 static void
1365 ttyblock(struct tty *tp)
1366 {
1367 	int	total;
1368 
1369 	total = tp->t_rawq.c_cc + tp->t_canq.c_cc;
1370 	if (tp->t_rawq.c_cc > TTYHOG) {
1371 		ttyflush(tp, FREAD | FWRITE);
1372 		CLR(tp->t_state, TS_TBLOCK);
1373 	}
1374 	/*
1375 	 * Block further input iff: current input > threshold
1376 	 * AND input is available to user program.
1377 	 */
1378 	if (total >= TTYHOG / 2 &&
1379 	    !ISSET(tp->t_state, TS_TBLOCK) &&
1380 	    (!ISSET(tp->t_lflag, ICANON) || tp->t_canq.c_cc > 0)) {
1381 		if (ISSET(tp->t_iflag, IXOFF) &&
1382 		    tp->t_cc[VSTOP] != _POSIX_VDISABLE &&
1383 		    putc(tp->t_cc[VSTOP], &tp->t_outq) == 0) {
1384 			SET(tp->t_state, TS_TBLOCK);
1385 			ttstart(tp);
1386 		}
1387 		/* Try to block remote output via hardware flow control. */
1388 		if (ISSET(tp->t_cflag, CHWFLOW) && tp->t_hwiflow &&
1389 		    (*tp->t_hwiflow)(tp, 1) != 0)
1390 			SET(tp->t_state, TS_TBLOCK);
1391 	}
1392 }
1393 
1394 /*
1395  * Delayed line discipline output
1396  */
1397 void
1398 ttrstrt(void *tp_arg)
1399 {
1400 	struct tty	*tp;
1401 	int		s;
1402 
1403 #ifdef DIAGNOSTIC
1404 	if (tp_arg == NULL)
1405 		panic("ttrstrt");
1406 #endif
1407 	tp = tp_arg;
1408 	s = spltty();
1409 	TTY_LOCK(tp);
1410 
1411 	CLR(tp->t_state, TS_TIMEOUT);
1412 	ttstart(tp); /* XXX - Shouldn't this be tp->l_start(tp)? */
1413 
1414 	TTY_UNLOCK(tp);
1415 	splx(s);
1416 }
1417 
1418 /*
1419  * start a line discipline
1420  * Always call at spltty() and with tty slock held?
1421  */
1422 int
1423 ttstart(struct tty *tp)
1424 {
1425 
1426 	if (tp->t_oproc != NULL)	/* XXX: Kludge for pty. */
1427 		(*tp->t_oproc)(tp);
1428 	return (0);
1429 }
1430 
1431 /*
1432  * "close" a line discipline
1433  */
1434 int
1435 ttylclose(struct tty *tp, int flag)
1436 {
1437 	int s;
1438 
1439 	if (flag & FNONBLOCK) {
1440 		s = spltty();
1441 		TTY_LOCK(tp);
1442 		ttyflush(tp, FREAD | FWRITE);
1443 		TTY_UNLOCK(tp);
1444 		splx(s);
1445 	} else
1446 		ttywflush(tp);
1447 	return (0);
1448 }
1449 
1450 /*
1451  * Handle modem control transition on a tty.
1452  * Flag indicates new state of carrier.
1453  * Returns 0 if the line should be turned off, otherwise 1.
1454  *
1455  * Must be called at spltty().
1456  */
1457 int
1458 ttymodem(struct tty *tp, int flag)
1459 {
1460 
1461 	TTY_LOCK(tp);
1462 	if (flag == 0) {
1463 		if (ISSET(tp->t_state, TS_CARR_ON)) {
1464 			/*
1465 			 * Lost carrier.
1466 			 */
1467 			CLR(tp->t_state, TS_CARR_ON);
1468 			if (ISSET(tp->t_state, TS_ISOPEN) && !CONNECTED(tp)) {
1469 				if (tp->t_session && tp->t_session->s_leader)
1470 					psignal(tp->t_session->s_leader,
1471 					    SIGHUP);
1472 				ttyflush(tp, FREAD | FWRITE);
1473 				TTY_UNLOCK(tp);
1474 				return (0);
1475 			}
1476 		}
1477 	} else {
1478 		if (!ISSET(tp->t_state, TS_CARR_ON)) {
1479 			/*
1480 			 * Carrier now on.
1481 			 */
1482 			SET(tp->t_state, TS_CARR_ON);
1483 			ttwakeup(tp);
1484 		}
1485 	}
1486 	TTY_UNLOCK(tp);
1487 	return (1);
1488 }
1489 
1490 /*
1491  * Default modem control routine (for other line disciplines).
1492  * Return argument flag, to turn off device on carrier drop.
1493  *
1494  * Must be called at spltty().
1495  */
1496 int
1497 nullmodem(struct tty *tp, int flag)
1498 {
1499 
1500 	TTY_LOCK(tp);
1501 	if (flag)
1502 		SET(tp->t_state, TS_CARR_ON);
1503 	else {
1504 		CLR(tp->t_state, TS_CARR_ON);
1505 		if (!CONNECTED(tp)) {
1506 			if (tp->t_session && tp->t_session->s_leader)
1507 				psignal(tp->t_session->s_leader, SIGHUP);
1508 			TTY_UNLOCK(tp);
1509 			return (0);
1510 		}
1511 	}
1512 	TTY_UNLOCK(tp);
1513 	return (1);
1514 }
1515 
1516 /*
1517  * Reinput pending characters after state switch.
1518  * Call at spltty() and with the tty slock held.
1519  */
1520 void
1521 ttypend(struct tty *tp)
1522 {
1523 	struct clist	tq;
1524 	int		c;
1525 
1526 	CLR(tp->t_lflag, PENDIN);
1527 	SET(tp->t_state, TS_TYPEN);
1528 	tq = tp->t_rawq;
1529 	tp->t_rawq.c_cc = 0;
1530 	tp->t_rawq.c_cf = tp->t_rawq.c_cl = 0;
1531 	while ((c = getc(&tq)) >= 0)
1532 		ttyinput_wlock(c, tp);
1533 	CLR(tp->t_state, TS_TYPEN);
1534 }
1535 
1536 /*
1537  * Process a read call on a tty device.
1538  */
1539 int
1540 ttread(struct tty *tp, struct uio *uio, int flag)
1541 {
1542 	struct clist	*qp;
1543 	u_char		*cc;
1544 	struct proc	*p;
1545 	int		c, s, first, error, has_stime, last_cc;
1546 	long		lflag, slp;
1547 	struct timeval	stime;
1548 
1549 	cc = tp->t_cc;
1550 	p = curproc;
1551 	error = 0;
1552 	has_stime = 0;
1553 	last_cc = 0;
1554 	slp = 0;
1555 
1556  loop:
1557 	s = spltty();
1558 	TTY_LOCK(tp);
1559 	lflag = tp->t_lflag;
1560 	/*
1561 	 * take pending input first
1562 	 */
1563 	if (ISSET(lflag, PENDIN))
1564 		ttypend(tp);
1565 
1566 	/*
1567 	 * Hang process if it's in the background.
1568 	 */
1569 	if (isbackground(p, tp)) {
1570 		if (sigismember(&p->p_sigctx.ps_sigignore, SIGTTIN) ||
1571 		    sigismember(&p->p_sigctx.ps_sigmask, SIGTTIN) ||
1572 		    p->p_flag & P_PPWAIT || p->p_pgrp->pg_jobc == 0) {
1573 			TTY_UNLOCK(tp);
1574 			splx(s);
1575 			return (EIO);
1576 		}
1577 		pgsignal(p->p_pgrp, SIGTTIN, 1);
1578 		error = ttysleep(tp, &lbolt, TTIPRI | PCATCH | PNORELOCK, ttybg, 0);
1579 		splx(s);
1580 		if (error)
1581 			return (error);
1582 		goto loop;
1583 	}
1584 
1585 	if (!ISSET(lflag, ICANON)) {
1586 		int m = cc[VMIN];
1587 		long t = cc[VTIME];
1588 
1589 		qp = &tp->t_rawq;
1590 		/*
1591 		 * Check each of the four combinations.
1592 		 * (m > 0 && t == 0) is the normal read case.
1593 		 * It should be fairly efficient, so we check that and its
1594 		 * companion case (m == 0 && t == 0) first.
1595 		 * For the other two cases, we compute the target sleep time
1596 		 * into slp.
1597 		 */
1598 		if (t == 0) {
1599 			if (qp->c_cc < m)
1600 				goto sleep;
1601 			goto read;
1602 		}
1603 		t *= 100000;		/* time in us */
1604 #define	diff(t1, t2) (((t1).tv_sec - (t2).tv_sec) * 1000000 + \
1605 			 ((t1).tv_usec - (t2).tv_usec))
1606 		if (m > 0) {
1607 			if (qp->c_cc <= 0)
1608 				goto sleep;
1609 			if (qp->c_cc >= m)
1610 				goto read;
1611 			if (!has_stime) {
1612 				/* first character, start timer */
1613 				has_stime = 1;
1614 				stime = time;
1615 				slp = t;
1616 			} else if (qp->c_cc > last_cc) {
1617 				/* got a character, restart timer */
1618 				stime = time;
1619 				slp = t;
1620 			} else {
1621 				/* nothing, check expiration */
1622 				slp = t - diff(time, stime);
1623 			}
1624 		} else {	/* m == 0 */
1625 			if (qp->c_cc > 0)
1626 				goto read;
1627 			if (!has_stime) {
1628 				has_stime = 1;
1629 				stime = time;
1630 				slp = t;
1631 			} else
1632 				slp = t - diff(time, stime);
1633 		}
1634 		last_cc = qp->c_cc;
1635 #undef diff
1636 		if (slp > 0) {
1637 			/*
1638 			 * Rounding down may make us wake up just short
1639 			 * of the target, so we round up.
1640 			 * The formula is ceiling(slp * hz/1000000).
1641 			 * 32-bit arithmetic is enough for hz < 169.
1642 			 *
1643 			 * Also, use plain wakeup() not ttwakeup().
1644 			 */
1645 			slp = (long) (((u_long)slp * hz) + 999999) / 1000000;
1646 			goto sleep;
1647 		}
1648 	} else if ((qp = &tp->t_canq)->c_cc <= 0) {
1649 		int	carrier;
1650 
1651  sleep:
1652 		/*
1653 		 * If there is no input, sleep on rawq
1654 		 * awaiting hardware receipt and notification.
1655 		 * If we have data, we don't need to check for carrier.
1656 		 */
1657 		carrier = CONNECTED(tp);
1658 		if (!carrier && ISSET(tp->t_state, TS_ISOPEN)) {
1659 			TTY_UNLOCK(tp);
1660 			splx(s);
1661 			return (0);	/* EOF */
1662 		}
1663 		if (flag & IO_NDELAY) {
1664 			TTY_UNLOCK(tp);
1665 			splx(s);
1666 			return (EWOULDBLOCK);
1667 		}
1668 		error = ttysleep(tp, &tp->t_rawq, TTIPRI | PCATCH | PNORELOCK,
1669 		    carrier ? ttyin : ttopen, slp);
1670 		splx(s);
1671 		/* VMIN == 0: any quantity read satisfies */
1672 		if (cc[VMIN] == 0 && error == EWOULDBLOCK)
1673 			return (0);
1674 		if (error && error != EWOULDBLOCK)
1675 			return (error);
1676 		goto loop;
1677 	}
1678  read:
1679 	TTY_UNLOCK(tp);
1680 	splx(s);
1681 
1682 	/*
1683 	 * Input present, check for input mapping and processing.
1684 	 */
1685 	first = 1;
1686 	while ((c = getc(qp)) >= 0) {
1687 		/*
1688 		 * delayed suspend (^Y)
1689 		 */
1690 		if (CCEQ(cc[VDSUSP], c) &&
1691 		    ISSET(lflag, IEXTEN|ISIG) == (IEXTEN|ISIG)) {
1692 			pgsignal(tp->t_pgrp, SIGTSTP, 1);
1693 			if (first) {
1694 				TTY_LOCK(tp);
1695 				error = ttysleep(tp, &lbolt,
1696 				    TTIPRI | PCATCH | PNORELOCK, ttybg, 0);
1697 				if (error)
1698 					break;
1699 				goto loop;
1700 			}
1701 			break;
1702 		}
1703 		/*
1704 		 * Interpret EOF only in canonical mode.
1705 		 */
1706 		if (CCEQ(cc[VEOF], c) && ISSET(lflag, ICANON))
1707 			break;
1708 		/*
1709 		 * Give user character.
1710 		 */
1711  		error = ureadc(c, uio);
1712 		if (error)
1713 			break;
1714  		if (uio->uio_resid == 0)
1715 			break;
1716 		/*
1717 		 * In canonical mode check for a "break character"
1718 		 * marking the end of a "line of input".
1719 		 */
1720 		if (ISSET(lflag, ICANON) && TTBREAKC(c, lflag))
1721 			break;
1722 		first = 0;
1723 	}
1724 	/*
1725 	 * Look to unblock output now that (presumably)
1726 	 * the input queue has gone down.
1727 	 */
1728 	s = spltty();
1729 	TTY_LOCK(tp);
1730 	if (ISSET(tp->t_state, TS_TBLOCK) && tp->t_rawq.c_cc < TTYHOG / 5) {
1731 		if (ISSET(tp->t_iflag, IXOFF) &&
1732 		    cc[VSTART] != _POSIX_VDISABLE &&
1733 		    putc(cc[VSTART], &tp->t_outq) == 0) {
1734 			CLR(tp->t_state, TS_TBLOCK);
1735 			ttstart(tp);
1736 		}
1737 		/* Try to unblock remote output via hardware flow control. */
1738 		if (ISSET(tp->t_cflag, CHWFLOW) && tp->t_hwiflow &&
1739 		    (*tp->t_hwiflow)(tp, 0) != 0)
1740 			CLR(tp->t_state, TS_TBLOCK);
1741 	}
1742 	TTY_UNLOCK(tp);
1743 	splx(s);
1744 	return (error);
1745 }
1746 
1747 /*
1748  * Check the output queue on tp for space for a kernel message (from uprintf
1749  * or tprintf).  Allow some space over the normal hiwater mark so we don't
1750  * lose messages due to normal flow control, but don't let the tty run amok.
1751  * Sleeps here are not interruptible, but we return prematurely if new signals
1752  * arrive.
1753  * Call with tty slock held.
1754  */
1755 static int
1756 ttycheckoutq_wlock(struct tty *tp, int wait)
1757 {
1758 	int	hiwat, s, error;
1759 
1760 	hiwat = tp->t_hiwat;
1761 	s = spltty();
1762 	if (tp->t_outq.c_cc > hiwat + 200)
1763 		while (tp->t_outq.c_cc > hiwat) {
1764 			ttstart(tp);
1765 			if (wait == 0) {
1766 				splx(s);
1767 				return (0);
1768 			}
1769 			SET(tp->t_state, TS_ASLEEP);
1770 			error = ltsleep(&tp->t_outq, (PZERO - 1) | PCATCH,
1771 			    "ttckoutq", hz, &tp->t_slock);
1772 			if (error == EINTR)
1773 				wait = 0;
1774 		}
1775 
1776 	splx(s);
1777 	return (1);
1778 }
1779 
1780 int
1781 ttycheckoutq(struct tty *tp, int wait)
1782 {
1783 	int	r, s;
1784 
1785 	s = spltty();
1786 	TTY_LOCK(tp);
1787 	r = ttycheckoutq_wlock(tp, wait);
1788 	TTY_UNLOCK(tp);
1789 	splx(s);
1790 	return (r);
1791 }
1792 
1793 /*
1794  * Process a write call on a tty device.
1795  */
1796 int
1797 ttwrite(struct tty *tp, struct uio *uio, int flag)
1798 {
1799 	u_char		*cp;
1800 	struct proc	*p;
1801 	int		cc, ce, i, hiwat, error, s;
1802 	size_t		cnt;
1803 	u_char		obuf[OBUFSIZ];
1804 
1805 	cp = NULL;
1806 	hiwat = tp->t_hiwat;
1807 	cnt = uio->uio_resid;
1808 	error = 0;
1809 	cc = 0;
1810  loop:
1811 	s = spltty();
1812 	TTY_LOCK(tp);
1813 	if (!CONNECTED(tp)) {
1814 		if (ISSET(tp->t_state, TS_ISOPEN)) {
1815 			TTY_UNLOCK(tp);
1816 			splx(s);
1817 			return (EIO);
1818 		} else if (flag & IO_NDELAY) {
1819 			TTY_UNLOCK(tp);
1820 			splx(s);
1821 			error = EWOULDBLOCK;
1822 			goto out;
1823 		} else {
1824 			/* Sleep awaiting carrier. */
1825 			error = ttysleep(tp,
1826 			    &tp->t_rawq, TTIPRI | PCATCH | PNORELOCK, ttopen, 0);
1827 			splx(s);
1828 			if (error)
1829 				goto out;
1830 			goto loop;
1831 		}
1832 	}
1833 	TTY_UNLOCK(tp);
1834 	splx(s);
1835 	/*
1836 	 * Hang the process if it's in the background.
1837 	 */
1838 	p = curproc;
1839 	if (isbackground(p, tp) &&
1840 	    ISSET(tp->t_lflag, TOSTOP) && (p->p_flag & P_PPWAIT) == 0 &&
1841 	    !sigismember(&p->p_sigctx.ps_sigignore, SIGTTOU) &&
1842 	    !sigismember(&p->p_sigctx.ps_sigmask, SIGTTOU)) {
1843 		if (p->p_pgrp->pg_jobc == 0) {
1844 			error = EIO;
1845 			goto out;
1846 		}
1847 		pgsignal(p->p_pgrp, SIGTTOU, 1);
1848 		s = spltty();
1849 		TTY_LOCK(tp);
1850 		error = ttysleep(tp, &lbolt, TTIPRI | PCATCH | PNORELOCK, ttybg, 0);
1851 		splx(s);
1852 		if (error)
1853 			goto out;
1854 		goto loop;
1855 	}
1856 	/*
1857 	 * Process the user's data in at most OBUFSIZ chunks.  Perform any
1858 	 * output translation.  Keep track of high water mark, sleep on
1859 	 * overflow awaiting device aid in acquiring new space.
1860 	 */
1861 	while (uio->uio_resid > 0 || cc > 0) {
1862 		if (ISSET(tp->t_lflag, FLUSHO)) {
1863 			TTY_UNLOCK(tp);
1864 			uio->uio_resid = 0;
1865 			return (0);
1866 		}
1867 		if (tp->t_outq.c_cc > hiwat)
1868 			goto ovhiwat;
1869 		/*
1870 		 * Grab a hunk of data from the user, unless we have some
1871 		 * leftover from last time.
1872 		 */
1873 		if (cc == 0) {
1874 			cc = min(uio->uio_resid, OBUFSIZ);
1875 			cp = obuf;
1876 			error = uiomove(cp, cc, uio);
1877 			if (error) {
1878 				cc = 0;
1879 				goto out;
1880 			}
1881 		}
1882 		/*
1883 		 * If nothing fancy need be done, grab those characters we
1884 		 * can handle without any of ttyoutput's processing and
1885 		 * just transfer them to the output q.  For those chars
1886 		 * which require special processing (as indicated by the
1887 		 * bits in char_type), call ttyoutput.  After processing
1888 		 * a hunk of data, look for FLUSHO so ^O's will take effect
1889 		 * immediately.
1890 		 */
1891 		s = spltty();
1892 		TTY_LOCK(tp);
1893 		while (cc > 0) {
1894 			if (!ISSET(tp->t_oflag, OPOST))
1895 				ce = cc;
1896 			else {
1897 				ce = cc - scanc((u_int)cc, cp, char_type,
1898 				    CCLASSMASK);
1899 				/*
1900 				 * If ce is zero, then we're processing
1901 				 * a special character through ttyoutput.
1902 				 */
1903 				if (ce == 0) {
1904 					tp->t_rocount = 0;
1905 					if (ttyoutput(*cp, tp) >= 0) {
1906 						/* out of space */
1907 						TTY_UNLOCK(tp);
1908 						splx(s);
1909 						goto overfull;
1910 					}
1911 					cp++;
1912 					cc--;
1913 					if (ISSET(tp->t_lflag, FLUSHO) ||
1914 					    tp->t_outq.c_cc > hiwat) {
1915 						TTY_UNLOCK(tp);
1916 						splx(s);
1917 						goto ovhiwat;
1918 					}
1919 					continue;
1920 				}
1921 			}
1922 			/*
1923 			 * A bunch of normal characters have been found.
1924 			 * Transfer them en masse to the output queue and
1925 			 * continue processing at the top of the loop.
1926 			 * If there are any further characters in this
1927 			 * <= OBUFSIZ chunk, the first should be a character
1928 			 * requiring special handling by ttyoutput.
1929 			 */
1930 			tp->t_rocount = 0;
1931 			i = b_to_q(cp, ce, &tp->t_outq);
1932 			ce -= i;
1933 			tp->t_column += ce;
1934 			cp += ce, cc -= ce, tk_nout += ce;
1935 			tp->t_outcc += ce;
1936 			if (i > 0) {
1937 				/* out of space */
1938 				TTY_UNLOCK(tp);
1939 				splx(s);
1940 				goto overfull;
1941 			}
1942 			if (ISSET(tp->t_lflag, FLUSHO) ||
1943 			    tp->t_outq.c_cc > hiwat)
1944 				break;
1945 		}
1946 		TTY_UNLOCK(tp);
1947 		splx(s);
1948 		ttstart(tp);
1949 	}
1950 
1951  out:
1952 	/*
1953 	 * If cc is nonzero, we leave the uio structure inconsistent, as the
1954 	 * offset and iov pointers have moved forward, but it doesn't matter
1955 	 * (the call will either return short or restart with a new uio).
1956 	 */
1957 	uio->uio_resid += cc;
1958 	return (error);
1959 
1960  overfull:
1961 	/*
1962 	 * Since we are using ring buffers, if we can't insert any more into
1963 	 * the output queue, we can assume the ring is full and that someone
1964 	 * forgot to set the high water mark correctly.  We set it and then
1965 	 * proceed as normal.
1966 	 */
1967 	hiwat = tp->t_outq.c_cc - 1;
1968 
1969  ovhiwat:
1970 	ttstart(tp);
1971 	s = spltty();
1972 	TTY_LOCK(tp);
1973 	/*
1974 	 * This can only occur if FLUSHO is set in t_lflag,
1975 	 * or if ttstart/oproc is synchronous (or very fast).
1976 	 */
1977 	if (tp->t_outq.c_cc <= hiwat) {
1978 		TTY_UNLOCK(tp);
1979 		splx(s);
1980 		goto loop;
1981 	}
1982 	if (flag & IO_NDELAY) {
1983 		TTY_UNLOCK(tp);
1984 		splx(s);
1985 		error = (uio->uio_resid == cnt) ? EWOULDBLOCK : 0;
1986 		goto out;
1987 	}
1988 	SET(tp->t_state, TS_ASLEEP);
1989 	error = ttysleep(tp, &tp->t_outq, TTOPRI | PCATCH | PNORELOCK, ttyout, 0);
1990 	splx(s);
1991 	if (error)
1992 		goto out;
1993 	goto loop;
1994 }
1995 
1996 /*
1997  * Rubout one character from the rawq of tp
1998  * as cleanly as possible.
1999  * Called with tty slock held.
2000  */
2001 void
2002 ttyrub(int c, struct tty *tp)
2003 {
2004 	u_char	*cp;
2005 	int	savecol, tabc, s;
2006 
2007 	if (!ISSET(tp->t_lflag, ECHO) || ISSET(tp->t_lflag, EXTPROC))
2008 		return;
2009 	CLR(tp->t_lflag, FLUSHO);
2010 	if (ISSET(tp->t_lflag, ECHOE)) {
2011 		if (tp->t_rocount == 0) {
2012 			/*
2013 			 * Screwed by ttwrite; retype
2014 			 */
2015 			ttyretype(tp);
2016 			return;
2017 		}
2018 		if (c == ('\t' | TTY_QUOTE) || c == ('\n' | TTY_QUOTE))
2019 			ttyrubo(tp, 2);
2020 		else {
2021 			CLR(c, ~TTY_CHARMASK);
2022 			switch (CCLASS(c)) {
2023 			case ORDINARY:
2024 				ttyrubo(tp, 1);
2025 				break;
2026 			case BACKSPACE:
2027 			case CONTROL:
2028 			case NEWLINE:
2029 			case RETURN:
2030 			case VTAB:
2031 				if (ISSET(tp->t_lflag, ECHOCTL))
2032 					ttyrubo(tp, 2);
2033 				break;
2034 			case TAB:
2035 				if (tp->t_rocount < tp->t_rawq.c_cc) {
2036 					ttyretype(tp);
2037 					return;
2038 				}
2039 				s = spltty();
2040 				savecol = tp->t_column;
2041 				SET(tp->t_state, TS_CNTTB);
2042 				SET(tp->t_lflag, FLUSHO);
2043 				tp->t_column = tp->t_rocol;
2044 				for (cp = firstc(&tp->t_rawq, &tabc); cp;
2045 				    cp = nextc(&tp->t_rawq, cp, &tabc))
2046 					ttyecho(tabc, tp);
2047 				CLR(tp->t_lflag, FLUSHO);
2048 				CLR(tp->t_state, TS_CNTTB);
2049 				splx(s);
2050 
2051 				/* savecol will now be length of the tab. */
2052 				savecol -= tp->t_column;
2053 				tp->t_column += savecol;
2054 				if (savecol > 8)
2055 					savecol = 8;	/* overflow screw */
2056 				while (--savecol >= 0)
2057 					(void)ttyoutput('\b', tp);
2058 				break;
2059 			default:			/* XXX */
2060 #define	PANICSTR	"ttyrub: would panic c = %d, val = %d\n"
2061 				(void)printf(PANICSTR, c, CCLASS(c));
2062 #ifdef notdef
2063 				panic(PANICSTR, c, CCLASS(c));
2064 #endif
2065 			}
2066 		}
2067 	} else if (ISSET(tp->t_lflag, ECHOPRT)) {
2068 		if (!ISSET(tp->t_state, TS_ERASE)) {
2069 			SET(tp->t_state, TS_ERASE);
2070 			(void)ttyoutput('\\', tp);
2071 		}
2072 		ttyecho(c, tp);
2073 	} else
2074 		ttyecho(tp->t_cc[VERASE], tp);
2075 	--tp->t_rocount;
2076 }
2077 
2078 /*
2079  * Back over cnt characters, erasing them.
2080  * Called with tty slock held.
2081  */
2082 static void
2083 ttyrubo(struct tty *tp, int cnt)
2084 {
2085 
2086 	while (cnt-- > 0) {
2087 		(void)ttyoutput('\b', tp);
2088 		(void)ttyoutput(' ', tp);
2089 		(void)ttyoutput('\b', tp);
2090 	}
2091 }
2092 
2093 /*
2094  * ttyretype --
2095  *	Reprint the rawq line.  Note, it is assumed that c_cc has already
2096  *	been checked.
2097  *
2098  * Called with tty slock held.
2099  */
2100 void
2101 ttyretype(struct tty *tp)
2102 {
2103 	u_char	*cp;
2104 	int	s, c;
2105 
2106 	/* Echo the reprint character. */
2107 	if (tp->t_cc[VREPRINT] != _POSIX_VDISABLE)
2108 		ttyecho(tp->t_cc[VREPRINT], tp);
2109 
2110 	(void)ttyoutput('\n', tp);
2111 
2112 	s = spltty();
2113 	for (cp = firstc(&tp->t_canq, &c); cp; cp = nextc(&tp->t_canq, cp, &c))
2114 		ttyecho(c, tp);
2115 	for (cp = firstc(&tp->t_rawq, &c); cp; cp = nextc(&tp->t_rawq, cp, &c))
2116 		ttyecho(c, tp);
2117 	CLR(tp->t_state, TS_ERASE);
2118 	splx(s);
2119 
2120 	tp->t_rocount = tp->t_rawq.c_cc;
2121 	tp->t_rocol = 0;
2122 }
2123 
2124 /*
2125  * Echo a typed character to the terminal.
2126  * Called with tty slock held.
2127  */
2128 static void
2129 ttyecho(int c, struct tty *tp)
2130 {
2131 
2132 	if (!ISSET(tp->t_state, TS_CNTTB))
2133 		CLR(tp->t_lflag, FLUSHO);
2134 	if ((!ISSET(tp->t_lflag, ECHO) &&
2135 	    (!ISSET(tp->t_lflag, ECHONL) || c != '\n')) ||
2136 	    ISSET(tp->t_lflag, EXTPROC))
2137 		return;
2138 	if (((ISSET(tp->t_lflag, ECHOCTL) &&
2139 	    (ISSET(c, TTY_CHARMASK) <= 037 && c != '\t' && c != '\n')) ||
2140 	    ISSET(c, TTY_CHARMASK) == 0177)) {
2141 		(void)ttyoutput('^', tp);
2142 		CLR(c, ~TTY_CHARMASK);
2143 		if (c == 0177)
2144 			c = '?';
2145 		else
2146 			c += 'A' - 1;
2147 	}
2148 	(void)ttyoutput(c, tp);
2149 }
2150 
2151 /*
2152  * Wake up any readers on a tty.
2153  * Called with tty slock held.
2154  */
2155 void
2156 ttwakeup(struct tty *tp)
2157 {
2158 
2159 	selnotify(&tp->t_rsel, 0);
2160 	if (ISSET(tp->t_state, TS_ASYNC))
2161 		pgsignal(tp->t_pgrp, SIGIO, 1);
2162 	wakeup((caddr_t)&tp->t_rawq);
2163 }
2164 
2165 /*
2166  * Look up a code for a specified speed in a conversion table;
2167  * used by drivers to map software speed values to hardware parameters.
2168  */
2169 int
2170 ttspeedtab(int speed, struct speedtab *table)
2171 {
2172 
2173 	for (; table->sp_speed != -1; table++)
2174 		if (table->sp_speed == speed)
2175 			return (table->sp_code);
2176 	return (-1);
2177 }
2178 
2179 /*
2180  * Set tty hi and low water marks.
2181  *
2182  * Try to arrange the dynamics so there's about one second
2183  * from hi to low water.
2184  */
2185 void
2186 ttsetwater(struct tty *tp)
2187 {
2188 	int	cps, x;
2189 
2190 #define	CLAMP(x, h, l)	((x) > h ? h : ((x) < l) ? l : (x))
2191 
2192 	cps = tp->t_ospeed / 10;
2193 	tp->t_lowat = x = CLAMP(cps / 2, TTMAXLOWAT, TTMINLOWAT);
2194 	x += cps;
2195 	x = CLAMP(x, TTMAXHIWAT, TTMINHIWAT);
2196 	tp->t_hiwat = roundup(x, CBSIZE);
2197 #undef	CLAMP
2198 }
2199 
2200 /*
2201  * Report on state of foreground process group.
2202  * Call with tty slock held.
2203  */
2204 void
2205 ttyinfo(struct tty *tp)
2206 {
2207 	struct lwp	*l;
2208 	struct proc	*p, *pick;
2209 	struct timeval	utime, stime;
2210 	int		tmp;
2211 
2212 	if (ttycheckoutq_wlock(tp, 0) == 0)
2213 		return;
2214 
2215 	/* Print load average. */
2216 	tmp = (averunnable.ldavg[0] * 100 + FSCALE / 2) >> FSHIFT;
2217 	ttyprintf_nolock(tp, "load: %d.%02d ", tmp / 100, tmp % 100);
2218 
2219 	if (tp->t_session == NULL)
2220 		ttyprintf_nolock(tp, "not a controlling terminal\n");
2221 	else if (tp->t_pgrp == NULL)
2222 		ttyprintf_nolock(tp, "no foreground process group\n");
2223 	else if ((p = LIST_FIRST(&tp->t_pgrp->pg_members)) == 0)
2224 		ttyprintf_nolock(tp, "empty foreground process group\n");
2225 	else {
2226 		/* Pick interesting process. */
2227 		for (pick = NULL; p != NULL; p = LIST_NEXT(p, p_pglist))
2228 			if (proc_compare(pick, p))
2229 				pick = p;
2230 
2231 		ttyprintf_nolock(tp, " cmd: %s %d [", pick->p_comm, pick->p_pid);
2232 		LIST_FOREACH(l, &pick->p_lwps, l_sibling)
2233 		    ttyprintf_nolock(tp, "%s%s",
2234 		    l->l_stat == LSONPROC ? "running" :
2235 		    l->l_stat == LSRUN ? "runnable" :
2236 		    l->l_wmesg ? l->l_wmesg : "iowait",
2237 			(LIST_NEXT(l, l_sibling) != NULL) ? " " : "] ");
2238 
2239 		calcru(pick, &utime, &stime, NULL);
2240 
2241 		/* Round up and print user time. */
2242 		utime.tv_usec += 5000;
2243 		if (utime.tv_usec >= 1000000) {
2244 			utime.tv_sec += 1;
2245 			utime.tv_usec -= 1000000;
2246 		}
2247 		ttyprintf_nolock(tp, "%ld.%02ldu ", (long int)utime.tv_sec,
2248 		    (long int)utime.tv_usec / 10000);
2249 
2250 		/* Round up and print system time. */
2251 		stime.tv_usec += 5000;
2252 		if (stime.tv_usec >= 1000000) {
2253 			stime.tv_sec += 1;
2254 			stime.tv_usec -= 1000000;
2255 		}
2256 		ttyprintf_nolock(tp, "%ld.%02lds ", (long int)stime.tv_sec,
2257 		    (long int)stime.tv_usec / 10000);
2258 
2259 #define	pgtok(a)	(((u_long) ((a) * PAGE_SIZE) / 1024))
2260 		/* Print percentage cpu. */
2261 		tmp = (pick->p_pctcpu * 10000 + FSCALE / 2) >> FSHIFT;
2262 		ttyprintf_nolock(tp, "%d%% ", tmp / 100);
2263 
2264 		/* Print resident set size. */
2265 		if (pick->p_stat == SIDL || P_ZOMBIE(pick))
2266 			tmp = 0;
2267 		else {
2268 			struct vmspace *vm = pick->p_vmspace;
2269 			tmp = pgtok(vm_resident_count(vm));
2270 		}
2271 		ttyprintf_nolock(tp, "%dk\n", tmp);
2272 	}
2273 	tp->t_rocount = 0;	/* so pending input will be retyped if BS */
2274 }
2275 
2276 /*
2277  * Returns 1 if p2 is "better" than p1
2278  *
2279  * The algorithm for picking the "interesting" process is thus:
2280  *
2281  *	1) Only foreground processes are eligible - implied.
2282  *	2) Runnable processes are favored over anything else.  The runner
2283  *	   with the highest cpu utilization is picked (p_estcpu).  Ties are
2284  *	   broken by picking the highest pid.
2285  *	3) The sleeper with the shortest sleep time is next.  With ties,
2286  *	   we pick out just "short-term" sleepers (P_SINTR == 0).
2287  *	4) Further ties are broken by picking the highest pid.
2288  */
2289 #define	ISRUN(p)	((p)->p_nrlwps > 0)
2290 #define	TESTAB(a, b)	((a)<<1 | (b))
2291 #define	ONLYA	2
2292 #define	ONLYB	1
2293 #define	BOTH	3
2294 
2295 static int
2296 proc_compare(struct proc *p1, struct proc *p2)
2297 {
2298 
2299 	if (p1 == NULL)
2300 		return (1);
2301 	/*
2302 	 * see if at least one of them is runnable
2303 	 */
2304 	switch (TESTAB(ISRUN(p1), ISRUN(p2))) {
2305 	case ONLYA:
2306 		return (0);
2307 	case ONLYB:
2308 		return (1);
2309 	case BOTH:
2310 		/*
2311 		 * tie - favor one with highest recent cpu utilization
2312 		 */
2313 		if (p2->p_estcpu > p1->p_estcpu)
2314 			return (1);
2315 		if (p1->p_estcpu > p2->p_estcpu)
2316 			return (0);
2317 		return (p2->p_pid > p1->p_pid);	/* tie - return highest pid */
2318 	}
2319 	/*
2320  	 * weed out zombies
2321 	 */
2322 	switch (TESTAB(P_ZOMBIE(p1), P_ZOMBIE(p2))) {
2323 	case ONLYA:
2324 		return (1);
2325 	case ONLYB:
2326 		return (0);
2327 	case BOTH:
2328 		return (p2->p_pid > p1->p_pid);	/* tie - return highest pid */
2329 	}
2330 #if 0 /* XXX NJWLWP */
2331 	/*
2332 	 * pick the one with the smallest sleep time
2333 	 */
2334 	if (p2->p_slptime > p1->p_slptime)
2335 		return (0);
2336 	if (p1->p_slptime > p2->p_slptime)
2337 		return (1);
2338 	/*
2339 	 * favor one sleeping in a non-interruptible sleep
2340 	 */
2341 	if (p1->p_flag & P_SINTR && (p2->p_flag & P_SINTR) == 0)
2342 		return (1);
2343 	if (p2->p_flag & P_SINTR && (p1->p_flag & P_SINTR) == 0)
2344 		return (0);
2345 #endif
2346 	return (p2->p_pid > p1->p_pid);		/* tie - return highest pid */
2347 }
2348 
2349 /*
2350  * Output char to tty; console putchar style.
2351  * Can be called with tty lock held through kprintf() machinery..
2352  */
2353 int
2354 tputchar(int c, int flags, struct tty *tp)
2355 {
2356 	int s, r = 0;
2357 
2358 	s = spltty();
2359 	if ((flags & NOLOCK) == 0)
2360 		simple_lock(&tp->t_slock);
2361 	if (!CONNECTED(tp)) {
2362 		r = -1;
2363 		goto out;
2364 	}
2365 	if (c == '\n')
2366 		(void)ttyoutput('\r', tp);
2367 	(void)ttyoutput(c, tp);
2368 	ttstart(tp);
2369 out:
2370 	if ((flags & NOLOCK) == 0)
2371 		TTY_UNLOCK(tp);
2372 	splx(s);
2373 	return (r);
2374 }
2375 
2376 /*
2377  * Sleep on chan, returning ERESTART if tty changed while we napped and
2378  * returning any errors (e.g. EINTR/ETIMEDOUT) reported by tsleep.  If
2379  * the tty is revoked, restarting a pending call will redo validation done
2380  * at the start of the call.
2381  *
2382  * Must be called with the tty slock held.
2383  */
2384 int
2385 ttysleep(struct tty *tp, void *chan, int pri, const char *wmesg, int timo)
2386 {
2387 	int	error;
2388 	short	gen;
2389 
2390 	gen = tp->t_gen;
2391 	if ((error = ltsleep(chan, pri, wmesg, timo, &tp->t_slock)) != 0)
2392 		return (error);
2393 	return (tp->t_gen == gen ? 0 : ERESTART);
2394 }
2395 
2396 /*
2397  * Initialise the global tty list.
2398  */
2399 void
2400 tty_init(void)
2401 {
2402 
2403 	ttyldisc_init();
2404 
2405 	TAILQ_INIT(&ttylist);
2406 	tty_count = 0;
2407 
2408 	pool_init(&tty_pool, sizeof(struct tty), 0, 0, 0, "ttypl",
2409 	    &pool_allocator_nointr);
2410 }
2411 
2412 /*
2413  * Attach a tty to the tty list.
2414  *
2415  * This should be called ONLY once per real tty (including pty's).
2416  * eg, on the sparc, the keyboard and mouse have struct tty's that are
2417  * distinctly NOT usable as tty's, and thus should not be attached to
2418  * the ttylist.  This is why this call is not done from ttymalloc().
2419  *
2420  * Device drivers should attach tty's at a similar time that they are
2421  * ttymalloc()'ed, or, for the case of statically allocated struct tty's
2422  * either in the attach or (first) open routine.
2423  */
2424 void
2425 tty_attach(struct tty *tp)
2426 {
2427 
2428 	simple_lock(&ttylist_slock);
2429 	TAILQ_INSERT_TAIL(&ttylist, tp, tty_link);
2430 	++tty_count;
2431 	simple_unlock(&ttylist_slock);
2432 }
2433 
2434 /*
2435  * Remove a tty from the tty list.
2436  */
2437 void
2438 tty_detach(struct tty *tp)
2439 {
2440 
2441 	simple_lock(&ttylist_slock);
2442 	--tty_count;
2443 #ifdef DIAGNOSTIC
2444 	if (tty_count < 0)
2445 		panic("tty_detach: tty_count < 0");
2446 #endif
2447 	TAILQ_REMOVE(&ttylist, tp, tty_link);
2448 	simple_unlock(&ttylist_slock);
2449 }
2450 
2451 /*
2452  * Allocate a tty structure and its associated buffers.
2453  */
2454 struct tty *
2455 ttymalloc(void)
2456 {
2457 	struct tty	*tp;
2458 
2459 	tp = pool_get(&tty_pool, PR_WAITOK);
2460 	memset(tp, 0, sizeof(*tp));
2461 	simple_lock_init(&tp->t_slock);
2462 	callout_init(&tp->t_rstrt_ch);
2463 	/* XXX: default to 1024 chars for now */
2464 	clalloc(&tp->t_rawq, 1024, 1);
2465 	clalloc(&tp->t_canq, 1024, 1);
2466 	/* output queue doesn't need quoting */
2467 	clalloc(&tp->t_outq, 1024, 0);
2468 	/* Set default line discipline. */
2469 	tp->t_linesw = linesw[0];
2470 	return (tp);
2471 }
2472 
2473 /*
2474  * Free a tty structure and its buffers.
2475  *
2476  * Be sure to call tty_detach() for any tty that has been
2477  * tty_attach()ed.
2478  */
2479 void
2480 ttyfree(struct tty *tp)
2481 {
2482 
2483 	callout_stop(&tp->t_rstrt_ch);
2484 	clfree(&tp->t_rawq);
2485 	clfree(&tp->t_canq);
2486 	clfree(&tp->t_outq);
2487 	pool_put(&tty_pool, tp);
2488 }
2489 
2490 /*
2491  * ttyprintf_nolock: send a message to a specific tty, without locking.
2492  *
2493  * => should be used only by tty driver or anything that knows the
2494  *    underlying tty will not be revoked(2)'d away.  [otherwise,
2495  *    use tprintf]
2496  */
2497 static void
2498 ttyprintf_nolock(struct tty *tp, const char *fmt, ...)
2499 {
2500 	va_list ap;
2501 
2502 	/* No mutex needed; going to process TTY. */
2503 	va_start(ap, fmt);
2504 	kprintf(fmt, TOTTY|NOLOCK, tp, NULL, ap);
2505 	va_end(ap);
2506 }
2507