blob: 46b2a1cc8b54af4caf14971ca24ac95be101a390 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * n_tty.c --- implements the N_TTY line discipline.
Alan Cox4edf1822008-02-08 04:18:44 -08003 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 * This code used to be in tty_io.c, but things are getting hairy
5 * enough that it made sense to split things off. (The N_TTY
6 * processing has changed so much that it's hardly recognizable,
7 * anyway...)
8 *
9 * Note that the open routine for N_TTY is guaranteed never to return
10 * an error. This is because Linux will fall back to setting a line
Alan Cox4edf1822008-02-08 04:18:44 -080011 * to N_TTY if it can not switch to any other line discipline.
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 *
13 * Written by Theodore Ts'o, Copyright 1994.
Alan Cox4edf1822008-02-08 04:18:44 -080014 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
Alan Cox4edf1822008-02-08 04:18:44 -080017 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 * This file may be redistributed under the terms of the GNU General Public
19 * License.
20 *
21 * Reduced memory usage for older ARM systems - Russell King.
22 *
Alan Cox4edf1822008-02-08 04:18:44 -080023 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
Linus Torvalds1da177e2005-04-16 15:20:36 -070024 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25 * who actually finally proved there really was a race.
26 *
27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29 * Also fixed a bug in BLOCKING mode where write_chan returns
30 * EAGAIN
31 */
32
33#include <linux/types.h>
34#include <linux/major.h>
35#include <linux/errno.h>
36#include <linux/signal.h>
37#include <linux/fcntl.h>
38#include <linux/sched.h>
39#include <linux/interrupt.h>
40#include <linux/tty.h>
41#include <linux/timer.h>
42#include <linux/ctype.h>
43#include <linux/mm.h>
44#include <linux/string.h>
45#include <linux/slab.h>
46#include <linux/poll.h>
47#include <linux/bitops.h>
Miloslav Trmac522ed772007-07-15 23:40:56 -070048#include <linux/audit.h>
49#include <linux/file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
51#include <asm/uaccess.h>
52#include <asm/system.h>
53
54/* number of characters left in xmit buffer before select has we have room */
55#define WAKEUP_CHARS 256
56
57/*
58 * This defines the low- and high-watermarks for throttling and
59 * unthrottling the TTY driver. These watermarks are used for
60 * controlling the space in the read buffer.
61 */
62#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
63#define TTY_THRESHOLD_UNTHROTTLE 128
64
65static inline unsigned char *alloc_buf(void)
66{
Al Virob4e3ca12005-10-21 03:22:34 -040067 gfp_t prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
69 if (PAGE_SIZE != N_TTY_BUF_SIZE)
70 return kmalloc(N_TTY_BUF_SIZE, prio);
71 else
72 return (unsigned char *)__get_free_page(prio);
73}
74
75static inline void free_buf(unsigned char *buf)
76{
77 if (PAGE_SIZE != N_TTY_BUF_SIZE)
78 kfree(buf);
79 else
80 free_page((unsigned long) buf);
81}
82
Miloslav Trmac522ed772007-07-15 23:40:56 -070083static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
84 unsigned char __user *ptr)
85{
86 tty_audit_add_data(tty, &x, 1);
87 return put_user(x, ptr);
88}
89
Alan Cox33f0f882006-01-09 20:54:13 -080090/**
91 * n_tty_set__room - receive space
92 * @tty: terminal
93 *
94 * Called by the driver to find out how much data it is
95 * permitted to feed to the line discipline without any being lost
96 * and thus to manage flow control. Not serialized. Answers for the
97 * "instant".
98 */
99
100static void n_tty_set_room(struct tty_struct *tty)
101{
102 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
103
104 /*
105 * If we are doing input canonicalization, and there are no
106 * pending newlines, let characters through without limit, so
107 * that erase characters will be handled. Other excess
108 * characters will be beeped.
109 */
110 if (left <= 0)
111 left = tty->icanon && !tty->canon_data;
112 tty->receive_room = left;
113}
114
115static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116{
117 if (tty->read_cnt < N_TTY_BUF_SIZE) {
118 tty->read_buf[tty->read_head] = c;
119 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
120 tty->read_cnt++;
121 }
122}
123
Alan Cox33f0f882006-01-09 20:54:13 -0800124static void put_tty_queue(unsigned char c, struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125{
126 unsigned long flags;
127 /*
128 * The problem of stomping on the buffers ends here.
129 * Why didn't anyone see this one coming? --AJK
130 */
131 spin_lock_irqsave(&tty->read_lock, flags);
132 put_tty_queue_nolock(c, tty);
133 spin_unlock_irqrestore(&tty->read_lock, flags);
134}
135
136/**
137 * check_unthrottle - allow new receive data
138 * @tty; tty device
139 *
140 * Check whether to call the driver.unthrottle function.
141 * We test the TTY_THROTTLED bit first so that it always
142 * indicates the current state. The decision about whether
143 * it is worth allowing more input has been taken by the caller.
Ingo Molnar70522e12006-03-23 03:00:31 -0800144 * Can sleep, may be called under the atomic_read_lock mutex but
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 * this is not guaranteed.
146 */
Alan Cox4edf1822008-02-08 04:18:44 -0800147
148static void check_unthrottle(struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149{
150 if (tty->count &&
Alan Cox4edf1822008-02-08 04:18:44 -0800151 test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 tty->driver->unthrottle)
153 tty->driver->unthrottle(tty);
154}
155
156/**
157 * reset_buffer_flags - reset buffer state
158 * @tty: terminal to reset
159 *
Alan Cox4edf1822008-02-08 04:18:44 -0800160 * Reset the read buffer counters, clear the flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 * and make sure the driver is unthrottled. Called
162 * from n_tty_open() and n_tty_flush_buffer().
163 */
164static void reset_buffer_flags(struct tty_struct *tty)
165{
166 unsigned long flags;
167
168 spin_lock_irqsave(&tty->read_lock, flags);
169 tty->read_head = tty->read_tail = tty->read_cnt = 0;
170 spin_unlock_irqrestore(&tty->read_lock, flags);
171 tty->canon_head = tty->canon_data = tty->erasing = 0;
172 memset(&tty->read_flags, 0, sizeof tty->read_flags);
Alan Cox33f0f882006-01-09 20:54:13 -0800173 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 check_unthrottle(tty);
175}
176
177/**
178 * n_tty_flush_buffer - clean input queue
179 * @tty: terminal device
180 *
181 * Flush the input buffer. Called when the line discipline is
182 * being closed, when the tty layer wants the buffer flushed (eg
183 * at hangup) or when the N_TTY line discipline internally has to
184 * clean the pending queue (for example some signals).
185 *
186 * FIXME: tty->ctrl_status is not spinlocked and relies on
187 * lock_kernel() still.
188 */
Alan Cox4edf1822008-02-08 04:18:44 -0800189
190static void n_tty_flush_buffer(struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191{
192 /* clear everything and unthrottle the driver */
193 reset_buffer_flags(tty);
Alan Cox4edf1822008-02-08 04:18:44 -0800194
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 if (!tty->link)
196 return;
197
198 if (tty->link->packet) {
199 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
200 wake_up_interruptible(&tty->link->read_wait);
201 }
202}
203
204/**
205 * n_tty_chars_in_buffer - report available bytes
206 * @tty: tty device
207 *
208 * Report the number of characters buffered to be delivered to user
Alan Cox4edf1822008-02-08 04:18:44 -0800209 * at this instant in time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 */
Alan Cox4edf1822008-02-08 04:18:44 -0800211
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
213{
214 unsigned long flags;
215 ssize_t n = 0;
216
217 spin_lock_irqsave(&tty->read_lock, flags);
218 if (!tty->icanon) {
219 n = tty->read_cnt;
220 } else if (tty->canon_data) {
221 n = (tty->canon_head > tty->read_tail) ?
222 tty->canon_head - tty->read_tail :
223 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
224 }
225 spin_unlock_irqrestore(&tty->read_lock, flags);
226 return n;
227}
228
229/**
230 * is_utf8_continuation - utf8 multibyte check
231 * @c: byte to check
232 *
233 * Returns true if the utf8 character 'c' is a multibyte continuation
234 * character. We use this to correctly compute the on screen size
235 * of the character when printing
236 */
Alan Cox4edf1822008-02-08 04:18:44 -0800237
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238static inline int is_utf8_continuation(unsigned char c)
239{
240 return (c & 0xc0) == 0x80;
241}
242
243/**
244 * is_continuation - multibyte check
245 * @c: byte to check
246 *
247 * Returns true if the utf8 character 'c' is a multibyte continuation
248 * character and the terminal is in unicode mode.
249 */
Alan Cox4edf1822008-02-08 04:18:44 -0800250
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251static inline int is_continuation(unsigned char c, struct tty_struct *tty)
252{
253 return I_IUTF8(tty) && is_utf8_continuation(c);
254}
255
256/**
257 * opost - output post processor
258 * @c: character (or partial unicode symbol)
259 * @tty: terminal device
260 *
261 * Perform OPOST processing. Returns -1 when the output device is
262 * full and the character must be retried. Note that Linux currently
263 * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
264 * relevant in the world today. If you ever need them, add them here.
265 *
266 * Called from both the receive and transmit sides and can be called
267 * re-entrantly. Relies on lock_kernel() still.
268 */
Alan Cox4edf1822008-02-08 04:18:44 -0800269
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270static int opost(unsigned char c, struct tty_struct *tty)
271{
272 int space, spaces;
273
274 space = tty->driver->write_room(tty);
275 if (!space)
276 return -1;
277
278 if (O_OPOST(tty)) {
279 switch (c) {
280 case '\n':
281 if (O_ONLRET(tty))
282 tty->column = 0;
283 if (O_ONLCR(tty)) {
284 if (space < 2)
285 return -1;
286 tty->driver->put_char(tty, '\r');
287 tty->column = 0;
288 }
289 tty->canon_column = tty->column;
290 break;
291 case '\r':
292 if (O_ONOCR(tty) && tty->column == 0)
293 return 0;
294 if (O_OCRNL(tty)) {
295 c = '\n';
296 if (O_ONLRET(tty))
297 tty->canon_column = tty->column = 0;
298 break;
299 }
300 tty->canon_column = tty->column = 0;
301 break;
302 case '\t':
303 spaces = 8 - (tty->column & 7);
304 if (O_TABDLY(tty) == XTABS) {
305 if (space < spaces)
306 return -1;
307 tty->column += spaces;
308 tty->driver->write(tty, " ", spaces);
309 return 0;
310 }
311 tty->column += spaces;
312 break;
313 case '\b':
314 if (tty->column > 0)
315 tty->column--;
316 break;
317 default:
318 if (O_OLCUC(tty))
319 c = toupper(c);
320 if (!iscntrl(c) && !is_continuation(c, tty))
321 tty->column++;
322 break;
323 }
324 }
325 tty->driver->put_char(tty, c);
326 return 0;
327}
328
329/**
330 * opost_block - block postprocess
331 * @tty: terminal device
332 * @inbuf: user buffer
333 * @nr: number of bytes
334 *
335 * This path is used to speed up block console writes, among other
336 * things when processing blocks of output data. It handles only
337 * the simple cases normally found and helps to generate blocks of
338 * symbols for the console driver and thus improve performance.
339 *
340 * Called from write_chan under the tty layer write lock.
341 */
Alan Cox4edf1822008-02-08 04:18:44 -0800342
343static ssize_t opost_block(struct tty_struct *tty,
344 const unsigned char *buf, unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345{
346 int space;
347 int i;
348 const unsigned char *cp;
349
350 space = tty->driver->write_room(tty);
351 if (!space)
352 return 0;
353 if (nr > space)
354 nr = space;
355
356 for (i = 0, cp = buf; i < nr; i++, cp++) {
357 switch (*cp) {
358 case '\n':
359 if (O_ONLRET(tty))
360 tty->column = 0;
361 if (O_ONLCR(tty))
362 goto break_out;
363 tty->canon_column = tty->column;
364 break;
365 case '\r':
366 if (O_ONOCR(tty) && tty->column == 0)
367 goto break_out;
368 if (O_OCRNL(tty))
369 goto break_out;
370 tty->canon_column = tty->column = 0;
371 break;
372 case '\t':
373 goto break_out;
374 case '\b':
375 if (tty->column > 0)
376 tty->column--;
377 break;
378 default:
379 if (O_OLCUC(tty))
380 goto break_out;
381 if (!iscntrl(*cp))
382 tty->column++;
383 break;
384 }
385 }
386break_out:
387 if (tty->driver->flush_chars)
388 tty->driver->flush_chars(tty);
Alan Cox4edf1822008-02-08 04:18:44 -0800389 i = tty->driver->write(tty, buf, i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 return i;
391}
392
393
394/**
395 * put_char - write character to driver
396 * @c: character (or part of unicode symbol)
397 * @tty: terminal device
398 *
399 * Queue a byte to the driver layer for output
400 */
Alan Cox4edf1822008-02-08 04:18:44 -0800401
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402static inline void put_char(unsigned char c, struct tty_struct *tty)
403{
404 tty->driver->put_char(tty, c);
405}
406
407/**
408 * echo_char - echo characters
409 * @c: unicode byte to echo
410 * @tty: terminal device
411 *
Alan Cox4edf1822008-02-08 04:18:44 -0800412 * Echo user input back onto the screen. This must be called only when
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 * L_ECHO(tty) is true. Called from the driver receive_buf path.
414 */
415
416static void echo_char(unsigned char c, struct tty_struct *tty)
417{
418 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
419 put_char('^', tty);
420 put_char(c ^ 0100, tty);
421 tty->column += 2;
422 } else
423 opost(c, tty);
424}
425
426static inline void finish_erasing(struct tty_struct *tty)
427{
428 if (tty->erasing) {
429 put_char('/', tty);
430 tty->column++;
431 tty->erasing = 0;
432 }
433}
434
435/**
436 * eraser - handle erase function
437 * @c: character input
438 * @tty: terminal device
439 *
Robert P. J. Day3a4fa0a2007-10-19 23:10:43 +0200440 * Perform erase and necessary output when an erase character is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441 * present in the stream from the driver layer. Handles the complexities
442 * of UTF-8 multibyte symbols.
443 */
Alan Cox4edf1822008-02-08 04:18:44 -0800444
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445static void eraser(unsigned char c, struct tty_struct *tty)
446{
447 enum { ERASE, WERASE, KILL } kill_type;
448 int head, seen_alnums, cnt;
449 unsigned long flags;
450
451 if (tty->read_head == tty->canon_head) {
452 /* opost('\a', tty); */ /* what do you think? */
453 return;
454 }
455 if (c == ERASE_CHAR(tty))
456 kill_type = ERASE;
457 else if (c == WERASE_CHAR(tty))
458 kill_type = WERASE;
459 else {
460 if (!L_ECHO(tty)) {
461 spin_lock_irqsave(&tty->read_lock, flags);
462 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
463 (N_TTY_BUF_SIZE - 1));
464 tty->read_head = tty->canon_head;
465 spin_unlock_irqrestore(&tty->read_lock, flags);
466 return;
467 }
468 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
469 spin_lock_irqsave(&tty->read_lock, flags);
470 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
471 (N_TTY_BUF_SIZE - 1));
472 tty->read_head = tty->canon_head;
473 spin_unlock_irqrestore(&tty->read_lock, flags);
474 finish_erasing(tty);
475 echo_char(KILL_CHAR(tty), tty);
476 /* Add a newline if ECHOK is on and ECHOKE is off. */
477 if (L_ECHOK(tty))
478 opost('\n', tty);
479 return;
480 }
481 kill_type = KILL;
482 }
483
484 seen_alnums = 0;
485 while (tty->read_head != tty->canon_head) {
486 head = tty->read_head;
487
488 /* erase a single possibly multibyte character */
489 do {
490 head = (head - 1) & (N_TTY_BUF_SIZE-1);
491 c = tty->read_buf[head];
492 } while (is_continuation(c, tty) && head != tty->canon_head);
493
494 /* do not partially erase */
495 if (is_continuation(c, tty))
496 break;
497
498 if (kill_type == WERASE) {
499 /* Equivalent to BSD's ALTWERASE. */
500 if (isalnum(c) || c == '_')
501 seen_alnums++;
502 else if (seen_alnums)
503 break;
504 }
505 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
506 spin_lock_irqsave(&tty->read_lock, flags);
507 tty->read_head = head;
508 tty->read_cnt -= cnt;
509 spin_unlock_irqrestore(&tty->read_lock, flags);
510 if (L_ECHO(tty)) {
511 if (L_ECHOPRT(tty)) {
512 if (!tty->erasing) {
513 put_char('\\', tty);
514 tty->column++;
515 tty->erasing = 1;
516 }
517 /* if cnt > 1, output a multi-byte character */
518 echo_char(c, tty);
519 while (--cnt > 0) {
520 head = (head+1) & (N_TTY_BUF_SIZE-1);
521 put_char(tty->read_buf[head], tty);
522 }
523 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
524 echo_char(ERASE_CHAR(tty), tty);
525 } else if (c == '\t') {
526 unsigned int col = tty->canon_column;
527 unsigned long tail = tty->canon_head;
528
529 /* Find the column of the last char. */
530 while (tail != tty->read_head) {
531 c = tty->read_buf[tail];
532 if (c == '\t')
533 col = (col | 7) + 1;
534 else if (iscntrl(c)) {
535 if (L_ECHOCTL(tty))
536 col += 2;
537 } else if (!is_continuation(c, tty))
538 col++;
539 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
540 }
541
542 /* should never happen */
543 if (tty->column > 0x80000000)
Alan Cox4edf1822008-02-08 04:18:44 -0800544 tty->column = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
546 /* Now backup to that column. */
547 while (tty->column > col) {
548 /* Can't use opost here. */
549 put_char('\b', tty);
550 if (tty->column > 0)
551 tty->column--;
552 }
553 } else {
554 if (iscntrl(c) && L_ECHOCTL(tty)) {
555 put_char('\b', tty);
556 put_char(' ', tty);
557 put_char('\b', tty);
558 if (tty->column > 0)
559 tty->column--;
560 }
561 if (!iscntrl(c) || L_ECHOCTL(tty)) {
562 put_char('\b', tty);
563 put_char(' ', tty);
564 put_char('\b', tty);
565 if (tty->column > 0)
566 tty->column--;
567 }
568 }
569 }
570 if (kill_type == ERASE)
571 break;
572 }
573 if (tty->read_head == tty->canon_head)
574 finish_erasing(tty);
575}
576
577/**
578 * isig - handle the ISIG optio
579 * @sig: signal
580 * @tty: terminal
581 * @flush: force flush
582 *
583 * Called when a signal is being sent due to terminal input. This
584 * may caus terminal flushing to take place according to the termios
585 * settings and character used. Called from the driver receive_buf
586 * path so serialized.
587 */
Alan Cox4edf1822008-02-08 04:18:44 -0800588
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589static inline void isig(int sig, struct tty_struct *tty, int flush)
590{
Eric W. Biedermanab521dc2007-02-12 00:53:00 -0800591 if (tty->pgrp)
592 kill_pgrp(tty->pgrp, sig, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 if (flush || !L_NOFLSH(tty)) {
594 n_tty_flush_buffer(tty);
595 if (tty->driver->flush_buffer)
596 tty->driver->flush_buffer(tty);
597 }
598}
599
600/**
601 * n_tty_receive_break - handle break
602 * @tty: terminal
603 *
604 * An RS232 break event has been hit in the incoming bitstream. This
605 * can cause a variety of events depending upon the termios settings.
606 *
607 * Called from the receive_buf path so single threaded.
608 */
Alan Cox4edf1822008-02-08 04:18:44 -0800609
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610static inline void n_tty_receive_break(struct tty_struct *tty)
611{
612 if (I_IGNBRK(tty))
613 return;
614 if (I_BRKINT(tty)) {
615 isig(SIGINT, tty, 1);
616 return;
617 }
618 if (I_PARMRK(tty)) {
619 put_tty_queue('\377', tty);
620 put_tty_queue('\0', tty);
621 }
622 put_tty_queue('\0', tty);
623 wake_up_interruptible(&tty->read_wait);
624}
625
626/**
627 * n_tty_receive_overrun - handle overrun reporting
628 * @tty: terminal
629 *
630 * Data arrived faster than we could process it. While the tty
631 * driver has flagged this the bits that were missed are gone
632 * forever.
633 *
634 * Called from the receive_buf path so single threaded. Does not
635 * need locking as num_overrun and overrun_time are function
636 * private.
637 */
Alan Cox4edf1822008-02-08 04:18:44 -0800638
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639static inline void n_tty_receive_overrun(struct tty_struct *tty)
640{
641 char buf[64];
642
643 tty->num_overrun++;
644 if (time_before(tty->overrun_time, jiffies - HZ) ||
645 time_after(tty->overrun_time, jiffies)) {
646 printk(KERN_WARNING "%s: %d input overrun(s)\n",
647 tty_name(tty, buf),
648 tty->num_overrun);
649 tty->overrun_time = jiffies;
650 tty->num_overrun = 0;
651 }
652}
653
654/**
655 * n_tty_receive_parity_error - error notifier
656 * @tty: terminal device
657 * @c: character
658 *
659 * Process a parity error and queue the right data to indicate
Robert P. J. Day3a4fa0a2007-10-19 23:10:43 +0200660 * the error case if necessary. Locking as per n_tty_receive_buf.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 */
662static inline void n_tty_receive_parity_error(struct tty_struct *tty,
663 unsigned char c)
664{
Alan Cox4edf1822008-02-08 04:18:44 -0800665 if (I_IGNPAR(tty))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 if (I_PARMRK(tty)) {
668 put_tty_queue('\377', tty);
669 put_tty_queue('\0', tty);
670 put_tty_queue(c, tty);
671 } else if (I_INPCK(tty))
672 put_tty_queue('\0', tty);
673 else
674 put_tty_queue(c, tty);
675 wake_up_interruptible(&tty->read_wait);
676}
677
678/**
679 * n_tty_receive_char - perform processing
680 * @tty: terminal device
681 * @c: character
682 *
683 * Process an individual character of input received from the driver.
Alan Cox4edf1822008-02-08 04:18:44 -0800684 * This is serialized with respect to itself by the rules for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 * driver above.
686 */
687
688static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
689{
690 unsigned long flags;
691
692 if (tty->raw) {
693 put_tty_queue(c, tty);
694 return;
695 }
Alan Cox4edf1822008-02-08 04:18:44 -0800696
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 if (I_ISTRIP(tty))
698 c &= 0x7f;
699 if (I_IUCLC(tty) && L_IEXTEN(tty))
700 c=tolower(c);
701
Joe Peterson54d2a372008-02-06 01:37:59 -0800702 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
703 ((I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty)) ||
704 c == INTR_CHAR(tty) || c == QUIT_CHAR(tty)))
705 start_tty(tty);
706
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707 if (tty->closing) {
708 if (I_IXON(tty)) {
709 if (c == START_CHAR(tty))
710 start_tty(tty);
711 else if (c == STOP_CHAR(tty))
712 stop_tty(tty);
713 }
714 return;
715 }
716
717 /*
718 * If the previous character was LNEXT, or we know that this
719 * character is not one of the characters that we'll have to
720 * handle specially, do shortcut processing to speed things
721 * up.
722 */
723 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
724 finish_erasing(tty);
725 tty->lnext = 0;
726 if (L_ECHO(tty)) {
727 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
728 put_char('\a', tty); /* beep if no space */
729 return;
730 }
731 /* Record the column of first canon char. */
732 if (tty->canon_head == tty->read_head)
733 tty->canon_column = tty->column;
734 echo_char(c, tty);
735 }
736 if (I_PARMRK(tty) && c == (unsigned char) '\377')
737 put_tty_queue(c, tty);
738 put_tty_queue(c, tty);
739 return;
740 }
Alan Cox4edf1822008-02-08 04:18:44 -0800741
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 if (c == '\r') {
743 if (I_IGNCR(tty))
744 return;
745 if (I_ICRNL(tty))
746 c = '\n';
747 } else if (c == '\n' && I_INLCR(tty))
748 c = '\r';
749 if (I_IXON(tty)) {
750 if (c == START_CHAR(tty)) {
751 start_tty(tty);
752 return;
753 }
754 if (c == STOP_CHAR(tty)) {
755 stop_tty(tty);
756 return;
757 }
758 }
759 if (L_ISIG(tty)) {
760 int signal;
761 signal = SIGINT;
762 if (c == INTR_CHAR(tty))
763 goto send_signal;
764 signal = SIGQUIT;
765 if (c == QUIT_CHAR(tty))
766 goto send_signal;
767 signal = SIGTSTP;
768 if (c == SUSP_CHAR(tty)) {
769send_signal:
Joe Petersonec5b1152008-02-06 01:37:38 -0800770 /*
771 * Echo character, and then send the signal.
772 * Note that we do not use isig() here because we want
773 * the order to be:
774 * 1) flush, 2) echo, 3) signal
775 */
776 if (!L_NOFLSH(tty)) {
777 n_tty_flush_buffer(tty);
778 if (tty->driver->flush_buffer)
779 tty->driver->flush_buffer(tty);
780 }
781 if (L_ECHO(tty))
782 echo_char(c, tty);
783 if (tty->pgrp)
784 kill_pgrp(tty->pgrp, signal, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 return;
786 }
787 }
788 if (tty->icanon) {
789 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
790 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
791 eraser(c, tty);
792 return;
793 }
794 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
795 tty->lnext = 1;
796 if (L_ECHO(tty)) {
797 finish_erasing(tty);
798 if (L_ECHOCTL(tty)) {
799 put_char('^', tty);
800 put_char('\b', tty);
801 }
802 }
803 return;
804 }
805 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
806 L_IEXTEN(tty)) {
807 unsigned long tail = tty->canon_head;
808
809 finish_erasing(tty);
810 echo_char(c, tty);
811 opost('\n', tty);
812 while (tail != tty->read_head) {
813 echo_char(tty->read_buf[tail], tty);
814 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
815 }
816 return;
817 }
818 if (c == '\n') {
819 if (L_ECHO(tty) || L_ECHONL(tty)) {
Roman Zippeld6afe272005-07-07 17:56:55 -0700820 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 put_char('\a', tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 opost('\n', tty);
823 }
824 goto handle_newline;
825 }
826 if (c == EOF_CHAR(tty)) {
Alan Cox4edf1822008-02-08 04:18:44 -0800827 if (tty->canon_head != tty->read_head)
828 set_bit(TTY_PUSH, &tty->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 c = __DISABLED_CHAR;
830 goto handle_newline;
831 }
832 if ((c == EOL_CHAR(tty)) ||
833 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
834 /*
835 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
836 */
837 if (L_ECHO(tty)) {
Roman Zippeld6afe272005-07-07 17:56:55 -0700838 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 put_char('\a', tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840 /* Record the column of first canon char. */
841 if (tty->canon_head == tty->read_head)
842 tty->canon_column = tty->column;
843 echo_char(c, tty);
844 }
845 /*
846 * XXX does PARMRK doubling happen for
847 * EOL_CHAR and EOL2_CHAR?
848 */
849 if (I_PARMRK(tty) && c == (unsigned char) '\377')
850 put_tty_queue(c, tty);
851
Alan Cox4edf1822008-02-08 04:18:44 -0800852handle_newline:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 spin_lock_irqsave(&tty->read_lock, flags);
854 set_bit(tty->read_head, tty->read_flags);
855 put_tty_queue_nolock(c, tty);
856 tty->canon_head = tty->read_head;
857 tty->canon_data++;
858 spin_unlock_irqrestore(&tty->read_lock, flags);
859 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
860 if (waitqueue_active(&tty->read_wait))
861 wake_up_interruptible(&tty->read_wait);
862 return;
863 }
864 }
Alan Cox4edf1822008-02-08 04:18:44 -0800865
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 finish_erasing(tty);
867 if (L_ECHO(tty)) {
868 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
869 put_char('\a', tty); /* beep if no space */
870 return;
871 }
872 if (c == '\n')
873 opost('\n', tty);
874 else {
875 /* Record the column of first canon char. */
876 if (tty->canon_head == tty->read_head)
877 tty->canon_column = tty->column;
878 echo_char(c, tty);
879 }
880 }
881
882 if (I_PARMRK(tty) && c == (unsigned char) '\377')
883 put_tty_queue(c, tty);
884
885 put_tty_queue(c, tty);
Alan Cox4edf1822008-02-08 04:18:44 -0800886}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888
889/**
890 * n_tty_write_wakeup - asynchronous I/O notifier
891 * @tty: tty device
892 *
893 * Required for the ptys, serial driver etc. since processes
894 * that attach themselves to the master and rely on ASYNC
895 * IO must be woken up
896 */
897
898static void n_tty_write_wakeup(struct tty_struct *tty)
899{
Alan Cox4edf1822008-02-08 04:18:44 -0800900 if (tty->fasync) {
901 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
903 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904}
905
906/**
907 * n_tty_receive_buf - data receive
908 * @tty: terminal device
909 * @cp: buffer
910 * @fp: flag buffer
911 * @count: characters
912 *
913 * Called by the terminal driver when a block of characters has
914 * been received. This function must be called from soft contexts
915 * not from interrupt context. The driver is responsible for making
916 * calls one at a time and in order (or using flush_to_ldisc)
917 */
Alan Cox4edf1822008-02-08 04:18:44 -0800918
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
920 char *fp, int count)
921{
922 const unsigned char *p;
923 char *f, flags = TTY_NORMAL;
924 int i;
925 char buf[64];
926 unsigned long cpuflags;
927
928 if (!tty->read_buf)
929 return;
930
931 if (tty->real_raw) {
932 spin_lock_irqsave(&tty->read_lock, cpuflags);
933 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
934 N_TTY_BUF_SIZE - tty->read_head);
935 i = min(count, i);
936 memcpy(tty->read_buf + tty->read_head, cp, i);
937 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
938 tty->read_cnt += i;
939 cp += i;
940 count -= i;
941
942 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
943 N_TTY_BUF_SIZE - tty->read_head);
944 i = min(count, i);
945 memcpy(tty->read_buf + tty->read_head, cp, i);
946 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
947 tty->read_cnt += i;
948 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
949 } else {
Alan Cox4edf1822008-02-08 04:18:44 -0800950 for (i = count, p = cp, f = fp; i; i--, p++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700951 if (f)
952 flags = *f++;
953 switch (flags) {
954 case TTY_NORMAL:
955 n_tty_receive_char(tty, *p);
956 break;
957 case TTY_BREAK:
958 n_tty_receive_break(tty);
959 break;
960 case TTY_PARITY:
961 case TTY_FRAME:
962 n_tty_receive_parity_error(tty, *p);
963 break;
964 case TTY_OVERRUN:
965 n_tty_receive_overrun(tty);
966 break;
967 default:
Alan Cox4edf1822008-02-08 04:18:44 -0800968 printk(KERN_ERR "%s: unknown flag %d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 tty_name(tty, buf), flags);
970 break;
971 }
972 }
973 if (tty->driver->flush_chars)
974 tty->driver->flush_chars(tty);
975 }
976
Alan Cox33f0f882006-01-09 20:54:13 -0800977 n_tty_set_room(tty);
978
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
980 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
981 if (waitqueue_active(&tty->read_wait))
982 wake_up_interruptible(&tty->read_wait);
983 }
984
985 /*
986 * Check the remaining room for the input canonicalization
987 * mode. We don't want to throttle the driver if we're in
988 * canonical mode and don't have a newline yet!
989 */
Alan Cox33f0f882006-01-09 20:54:13 -0800990 if (tty->receive_room < TTY_THRESHOLD_THROTTLE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 /* check TTY_THROTTLED first so it indicates our state */
992 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
993 tty->driver->throttle)
994 tty->driver->throttle(tty);
995 }
996}
997
998int is_ignored(int sig)
999{
1000 return (sigismember(&current->blocked, sig) ||
Alan Cox4edf1822008-02-08 04:18:44 -08001001 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002}
1003
1004/**
1005 * n_tty_set_termios - termios data changed
1006 * @tty: terminal
1007 * @old: previous data
1008 *
1009 * Called by the tty layer when the user changes termios flags so
1010 * that the line discipline can plan ahead. This function cannot sleep
Alan Cox4edf1822008-02-08 04:18:44 -08001011 * and is protected from re-entry by the tty layer. The user is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 * guaranteed that this function will not be re-entered or in progress
1013 * when the ldisc is closed.
1014 */
Alan Cox4edf1822008-02-08 04:18:44 -08001015
1016static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017{
1018 if (!tty)
1019 return;
Alan Cox4edf1822008-02-08 04:18:44 -08001020
Linus Torvalds1da177e2005-04-16 15:20:36 -07001021 tty->icanon = (L_ICANON(tty) != 0);
1022 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1023 tty->raw = 1;
1024 tty->real_raw = 1;
Alan Cox33f0f882006-01-09 20:54:13 -08001025 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 return;
1027 }
1028 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1029 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1030 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1031 I_PARMRK(tty)) {
1032 memset(tty->process_char_map, 0, 256/8);
1033
1034 if (I_IGNCR(tty) || I_ICRNL(tty))
1035 set_bit('\r', tty->process_char_map);
1036 if (I_INLCR(tty))
1037 set_bit('\n', tty->process_char_map);
1038
1039 if (L_ICANON(tty)) {
1040 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1041 set_bit(KILL_CHAR(tty), tty->process_char_map);
1042 set_bit(EOF_CHAR(tty), tty->process_char_map);
1043 set_bit('\n', tty->process_char_map);
1044 set_bit(EOL_CHAR(tty), tty->process_char_map);
1045 if (L_IEXTEN(tty)) {
1046 set_bit(WERASE_CHAR(tty),
1047 tty->process_char_map);
1048 set_bit(LNEXT_CHAR(tty),
1049 tty->process_char_map);
1050 set_bit(EOL2_CHAR(tty),
1051 tty->process_char_map);
1052 if (L_ECHO(tty))
1053 set_bit(REPRINT_CHAR(tty),
1054 tty->process_char_map);
1055 }
1056 }
1057 if (I_IXON(tty)) {
1058 set_bit(START_CHAR(tty), tty->process_char_map);
1059 set_bit(STOP_CHAR(tty), tty->process_char_map);
1060 }
1061 if (L_ISIG(tty)) {
1062 set_bit(INTR_CHAR(tty), tty->process_char_map);
1063 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1064 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1065 }
1066 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1067 tty->raw = 0;
1068 tty->real_raw = 0;
1069 } else {
1070 tty->raw = 1;
1071 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1072 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1073 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1074 tty->real_raw = 1;
1075 else
1076 tty->real_raw = 0;
1077 }
Alan Cox33f0f882006-01-09 20:54:13 -08001078 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079}
1080
1081/**
1082 * n_tty_close - close the ldisc for this tty
1083 * @tty: device
1084 *
Alan Cox4edf1822008-02-08 04:18:44 -08001085 * Called from the terminal layer when this line discipline is
1086 * being shut down, either because of a close or becsuse of a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 * discipline change. The function will not be called while other
1088 * ldisc methods are in progress.
1089 */
Alan Cox4edf1822008-02-08 04:18:44 -08001090
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091static void n_tty_close(struct tty_struct *tty)
1092{
1093 n_tty_flush_buffer(tty);
1094 if (tty->read_buf) {
1095 free_buf(tty->read_buf);
1096 tty->read_buf = NULL;
1097 }
1098}
1099
1100/**
1101 * n_tty_open - open an ldisc
1102 * @tty: terminal to open
1103 *
Alan Cox4edf1822008-02-08 04:18:44 -08001104 * Called when this line discipline is being attached to the
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 * terminal device. Can sleep. Called serialized so that no
1106 * other events will occur in parallel. No further open will occur
1107 * until a close.
1108 */
1109
1110static int n_tty_open(struct tty_struct *tty)
1111{
1112 if (!tty)
1113 return -EINVAL;
1114
1115 /* This one is ugly. Currently a malloc failure here can panic */
1116 if (!tty->read_buf) {
1117 tty->read_buf = alloc_buf();
1118 if (!tty->read_buf)
1119 return -ENOMEM;
1120 }
1121 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1122 reset_buffer_flags(tty);
1123 tty->column = 0;
1124 n_tty_set_termios(tty, NULL);
1125 tty->minimum_to_wake = 1;
1126 tty->closing = 0;
1127 return 0;
1128}
1129
1130static inline int input_available_p(struct tty_struct *tty, int amt)
1131{
1132 if (tty->icanon) {
1133 if (tty->canon_data)
1134 return 1;
1135 } else if (tty->read_cnt >= (amt ? amt : 1))
1136 return 1;
1137
1138 return 0;
1139}
1140
1141/**
1142 * copy_from_read_buf - copy read data directly
1143 * @tty: terminal device
1144 * @b: user data
1145 * @nr: size of data
1146 *
1147 * Helper function to speed up read_chan. It is only called when
1148 * ICANON is off; it copies characters straight from the tty queue to
1149 * user space directly. It can be profitably called twice; once to
1150 * drain the space from the tail pointer to the (physical) end of the
1151 * buffer, and once to drain the space from the (physical) beginning of
1152 * the buffer to head pointer.
1153 *
Paul Fulghum817d6d32006-06-28 04:26:47 -07001154 * Called under the tty->atomic_read_lock sem
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155 *
1156 */
Alan Cox4edf1822008-02-08 04:18:44 -08001157
Alan Cox33f0f882006-01-09 20:54:13 -08001158static int copy_from_read_buf(struct tty_struct *tty,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 unsigned char __user **b,
1160 size_t *nr)
1161
1162{
1163 int retval;
1164 size_t n;
1165 unsigned long flags;
1166
1167 retval = 0;
1168 spin_lock_irqsave(&tty->read_lock, flags);
1169 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1170 n = min(*nr, n);
1171 spin_unlock_irqrestore(&tty->read_lock, flags);
1172 if (n) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1174 n -= retval;
Miloslav Trmac522ed772007-07-15 23:40:56 -07001175 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 spin_lock_irqsave(&tty->read_lock, flags);
1177 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1178 tty->read_cnt -= n;
1179 spin_unlock_irqrestore(&tty->read_lock, flags);
1180 *b += n;
1181 *nr -= n;
1182 }
1183 return retval;
1184}
1185
Alan Cox4edf1822008-02-08 04:18:44 -08001186extern ssize_t redirected_tty_write(struct file *, const char *,
1187 size_t, loff_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188
1189/**
1190 * job_control - check job control
1191 * @tty: tty
1192 * @file: file handle
1193 *
1194 * Perform job control management checks on this file/tty descriptor
Alan Cox4edf1822008-02-08 04:18:44 -08001195 * and if appropriate send any needed signals and return a negative
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196 * error code if action should be taken.
1197 */
Alan Cox4edf1822008-02-08 04:18:44 -08001198
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199static int job_control(struct tty_struct *tty, struct file *file)
1200{
1201 /* Job control check -- must be done at start and after
1202 every sleep (POSIX.1 7.1.1.4). */
1203 /* NOTE: not yet done after every sleep pending a thorough
1204 check of the logic of this change. -- jlc */
1205 /* don't stop on /dev/console */
1206 if (file->f_op->write != redirected_tty_write &&
1207 current->signal->tty == tty) {
Eric W. Biedermanab521dc2007-02-12 00:53:00 -08001208 if (!tty->pgrp)
Alan Cox4edf1822008-02-08 04:18:44 -08001209 printk(KERN_ERR "read_chan: no tty->pgrp!\n");
Eric W. Biedermanab521dc2007-02-12 00:53:00 -08001210 else if (task_pgrp(current) != tty->pgrp) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211 if (is_ignored(SIGTTIN) ||
Eric W. Biederman3e7cd6c2007-02-12 00:52:58 -08001212 is_current_pgrp_orphaned())
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213 return -EIO;
Eric W. Biedermanab521dc2007-02-12 00:53:00 -08001214 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
Oleg Nesterov040b6362007-06-01 00:46:53 -07001215 set_thread_flag(TIF_SIGPENDING);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 return -ERESTARTSYS;
1217 }
1218 }
1219 return 0;
1220}
Alan Cox4edf1822008-02-08 04:18:44 -08001221
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222
1223/**
1224 * read_chan - read function for tty
1225 * @tty: tty device
1226 * @file: file object
1227 * @buf: userspace buffer pointer
1228 * @nr: size of I/O
1229 *
1230 * Perform reads for the line discipline. We are guaranteed that the
1231 * line discipline will not be closed under us but we may get multiple
1232 * parallel readers and must handle this ourselves. We may also get
1233 * a hangup. Always called in user context, may sleep.
1234 *
1235 * This code must be sure never to sleep through a hangup.
1236 */
Alan Cox4edf1822008-02-08 04:18:44 -08001237
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238static ssize_t read_chan(struct tty_struct *tty, struct file *file,
1239 unsigned char __user *buf, size_t nr)
1240{
1241 unsigned char __user *b = buf;
1242 DECLARE_WAITQUEUE(wait, current);
1243 int c;
1244 int minimum, time;
1245 ssize_t retval = 0;
1246 ssize_t size;
1247 long timeout;
1248 unsigned long flags;
1249
1250do_it_again:
1251
1252 if (!tty->read_buf) {
Alan Cox4edf1822008-02-08 04:18:44 -08001253 printk(KERN_ERR "n_tty_read_chan: read_buf == NULL?!?\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 return -EIO;
1255 }
1256
1257 c = job_control(tty, file);
Alan Cox4edf1822008-02-08 04:18:44 -08001258 if (c < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259 return c;
Alan Cox4edf1822008-02-08 04:18:44 -08001260
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 minimum = time = 0;
1262 timeout = MAX_SCHEDULE_TIMEOUT;
1263 if (!tty->icanon) {
1264 time = (HZ / 10) * TIME_CHAR(tty);
1265 minimum = MIN_CHAR(tty);
1266 if (minimum) {
1267 if (time)
1268 tty->minimum_to_wake = 1;
1269 else if (!waitqueue_active(&tty->read_wait) ||
1270 (tty->minimum_to_wake > minimum))
1271 tty->minimum_to_wake = minimum;
1272 } else {
1273 timeout = 0;
1274 if (time) {
1275 timeout = time;
1276 time = 0;
1277 }
1278 tty->minimum_to_wake = minimum = 1;
1279 }
1280 }
1281
1282 /*
1283 * Internal serialization of reads.
1284 */
1285 if (file->f_flags & O_NONBLOCK) {
Ingo Molnar70522e12006-03-23 03:00:31 -08001286 if (!mutex_trylock(&tty->atomic_read_lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287 return -EAGAIN;
Alan Cox4edf1822008-02-08 04:18:44 -08001288 } else {
Ingo Molnar70522e12006-03-23 03:00:31 -08001289 if (mutex_lock_interruptible(&tty->atomic_read_lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 return -ERESTARTSYS;
1291 }
1292
1293 add_wait_queue(&tty->read_wait, &wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 while (nr) {
1295 /* First test for status change. */
1296 if (tty->packet && tty->link->ctrl_status) {
1297 unsigned char cs;
1298 if (b != buf)
1299 break;
1300 cs = tty->link->ctrl_status;
1301 tty->link->ctrl_status = 0;
Miloslav Trmac522ed772007-07-15 23:40:56 -07001302 if (tty_put_user(tty, cs, b++)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 retval = -EFAULT;
1304 b--;
1305 break;
1306 }
1307 nr--;
1308 break;
1309 }
1310 /* This statement must be first before checking for input
1311 so that any interrupt will set the state back to
1312 TASK_RUNNING. */
1313 set_current_state(TASK_INTERRUPTIBLE);
Alan Cox4edf1822008-02-08 04:18:44 -08001314
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1316 ((minimum - (b - buf)) >= 1))
1317 tty->minimum_to_wake = (minimum - (b - buf));
Alan Cox4edf1822008-02-08 04:18:44 -08001318
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 if (!input_available_p(tty, 0)) {
1320 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1321 retval = -EIO;
1322 break;
1323 }
1324 if (tty_hung_up_p(file))
1325 break;
1326 if (!timeout)
1327 break;
1328 if (file->f_flags & O_NONBLOCK) {
1329 retval = -EAGAIN;
1330 break;
1331 }
1332 if (signal_pending(current)) {
1333 retval = -ERESTARTSYS;
1334 break;
1335 }
Alan Cox33f0f882006-01-09 20:54:13 -08001336 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337 timeout = schedule_timeout(timeout);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 continue;
1339 }
1340 __set_current_state(TASK_RUNNING);
1341
1342 /* Deal with packet mode. */
1343 if (tty->packet && b == buf) {
Miloslav Trmac522ed772007-07-15 23:40:56 -07001344 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 retval = -EFAULT;
1346 b--;
1347 break;
1348 }
1349 nr--;
1350 }
1351
1352 if (tty->icanon) {
1353 /* N.B. avoid overrun if nr == 0 */
1354 while (nr && tty->read_cnt) {
Alan Cox4edf1822008-02-08 04:18:44 -08001355 int eol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356
1357 eol = test_and_clear_bit(tty->read_tail,
1358 tty->read_flags);
1359 c = tty->read_buf[tty->read_tail];
1360 spin_lock_irqsave(&tty->read_lock, flags);
1361 tty->read_tail = ((tty->read_tail+1) &
1362 (N_TTY_BUF_SIZE-1));
1363 tty->read_cnt--;
1364 if (eol) {
1365 /* this test should be redundant:
1366 * we shouldn't be reading data if
1367 * canon_data is 0
1368 */
1369 if (--tty->canon_data < 0)
1370 tty->canon_data = 0;
1371 }
1372 spin_unlock_irqrestore(&tty->read_lock, flags);
1373
1374 if (!eol || (c != __DISABLED_CHAR)) {
Miloslav Trmac522ed772007-07-15 23:40:56 -07001375 if (tty_put_user(tty, c, b++)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 retval = -EFAULT;
1377 b--;
1378 break;
1379 }
1380 nr--;
1381 }
Miloslav Trmac522ed772007-07-15 23:40:56 -07001382 if (eol) {
1383 tty_audit_push(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 break;
Miloslav Trmac522ed772007-07-15 23:40:56 -07001385 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386 }
1387 if (retval)
1388 break;
1389 } else {
1390 int uncopied;
1391 uncopied = copy_from_read_buf(tty, &b, &nr);
1392 uncopied += copy_from_read_buf(tty, &b, &nr);
1393 if (uncopied) {
1394 retval = -EFAULT;
1395 break;
1396 }
1397 }
1398
1399 /* If there is enough space in the read buffer now, let the
1400 * low-level driver know. We use n_tty_chars_in_buffer() to
1401 * check the buffer, as it now knows about canonical mode.
1402 * Otherwise, if the driver is throttled and the line is
1403 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1404 * we won't get any more characters.
1405 */
Paul Mackerras289a1e92006-06-12 12:16:26 +10001406 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1407 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 check_unthrottle(tty);
Paul Mackerras289a1e92006-06-12 12:16:26 +10001409 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410
1411 if (b - buf >= minimum)
1412 break;
1413 if (time)
1414 timeout = time;
1415 }
Ingo Molnar70522e12006-03-23 03:00:31 -08001416 mutex_unlock(&tty->atomic_read_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 remove_wait_queue(&tty->read_wait, &wait);
1418
1419 if (!waitqueue_active(&tty->read_wait))
1420 tty->minimum_to_wake = minimum;
1421
1422 __set_current_state(TASK_RUNNING);
1423 size = b - buf;
1424 if (size) {
1425 retval = size;
1426 if (nr)
Alan Cox4edf1822008-02-08 04:18:44 -08001427 clear_bit(TTY_PUSH, &tty->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1429 goto do_it_again;
1430
Alan Cox33f0f882006-01-09 20:54:13 -08001431 n_tty_set_room(tty);
1432
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 return retval;
1434}
1435
1436/**
1437 * write_chan - write function for tty
1438 * @tty: tty device
1439 * @file: file object
1440 * @buf: userspace buffer pointer
1441 * @nr: size of I/O
1442 *
1443 * Write function of the terminal device. This is serialized with
1444 * respect to other write callers but not to termios changes, reads
1445 * and other such events. We must be careful with N_TTY as the receive
1446 * code will echo characters, thus calling driver write methods.
1447 *
1448 * This code must be sure never to sleep through a hangup.
1449 */
Alan Cox4edf1822008-02-08 04:18:44 -08001450
1451static ssize_t write_chan(struct tty_struct *tty, struct file *file,
1452 const unsigned char *buf, size_t nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453{
1454 const unsigned char *b = buf;
1455 DECLARE_WAITQUEUE(wait, current);
1456 int c;
1457 ssize_t retval = 0;
1458
1459 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1460 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1461 retval = tty_check_change(tty);
1462 if (retval)
1463 return retval;
1464 }
1465
1466 add_wait_queue(&tty->write_wait, &wait);
1467 while (1) {
1468 set_current_state(TASK_INTERRUPTIBLE);
1469 if (signal_pending(current)) {
1470 retval = -ERESTARTSYS;
1471 break;
1472 }
1473 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1474 retval = -EIO;
1475 break;
1476 }
1477 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1478 while (nr > 0) {
1479 ssize_t num = opost_block(tty, b, nr);
1480 if (num < 0) {
1481 if (num == -EAGAIN)
1482 break;
1483 retval = num;
1484 goto break_out;
1485 }
1486 b += num;
1487 nr -= num;
1488 if (nr == 0)
1489 break;
1490 c = *b;
1491 if (opost(c, tty) < 0)
1492 break;
1493 b++; nr--;
1494 }
1495 if (tty->driver->flush_chars)
1496 tty->driver->flush_chars(tty);
1497 } else {
Roman Zippeld6afe272005-07-07 17:56:55 -07001498 while (nr > 0) {
1499 c = tty->driver->write(tty, b, nr);
1500 if (c < 0) {
1501 retval = c;
1502 goto break_out;
1503 }
1504 if (!c)
1505 break;
1506 b += c;
1507 nr -= c;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 }
1510 if (!nr)
1511 break;
1512 if (file->f_flags & O_NONBLOCK) {
1513 retval = -EAGAIN;
1514 break;
1515 }
1516 schedule();
1517 }
1518break_out:
1519 __set_current_state(TASK_RUNNING);
1520 remove_wait_queue(&tty->write_wait, &wait);
1521 return (b - buf) ? b - buf : retval;
1522}
1523
1524/**
1525 * normal_poll - poll method for N_TTY
1526 * @tty: terminal device
1527 * @file: file accessing it
1528 * @wait: poll table
1529 *
1530 * Called when the line discipline is asked to poll() for data or
1531 * for special events. This code is not serialized with respect to
1532 * other events save open/close.
1533 *
1534 * This code must be sure never to sleep through a hangup.
1535 * Called without the kernel lock held - fine
1536 *
1537 * FIXME: if someone changes the VMIN or discipline settings for the
1538 * terminal while another process is in poll() the poll does not
1539 * recompute the new limits. Possibly set_termios should issue
1540 * a read wakeup to fix this bug.
1541 */
Alan Cox4edf1822008-02-08 04:18:44 -08001542
1543static unsigned int normal_poll(struct tty_struct *tty, struct file *file,
1544 poll_table *wait)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545{
1546 unsigned int mask = 0;
1547
1548 poll_wait(file, &tty->read_wait, wait);
1549 poll_wait(file, &tty->write_wait, wait);
1550 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1551 mask |= POLLIN | POLLRDNORM;
1552 if (tty->packet && tty->link->ctrl_status)
1553 mask |= POLLPRI | POLLIN | POLLRDNORM;
1554 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1555 mask |= POLLHUP;
1556 if (tty_hung_up_p(file))
1557 mask |= POLLHUP;
1558 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1559 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1560 tty->minimum_to_wake = MIN_CHAR(tty);
1561 else
1562 tty->minimum_to_wake = 1;
1563 }
Alan Cox9c1729d2007-07-15 23:39:43 -07001564 if (!tty_is_writelocked(tty) &&
1565 tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566 tty->driver->write_room(tty) > 0)
1567 mask |= POLLOUT | POLLWRNORM;
1568 return mask;
1569}
1570
1571struct tty_ldisc tty_ldisc_N_TTY = {
Paul Fulghume10cc1d2007-05-10 22:22:50 -07001572 .magic = TTY_LDISC_MAGIC,
1573 .name = "n_tty",
1574 .open = n_tty_open,
1575 .close = n_tty_close,
1576 .flush_buffer = n_tty_flush_buffer,
1577 .chars_in_buffer = n_tty_chars_in_buffer,
1578 .read = read_chan,
1579 .write = write_chan,
1580 .ioctl = n_tty_ioctl,
1581 .set_termios = n_tty_set_termios,
1582 .poll = normal_poll,
1583 .receive_buf = n_tty_receive_buf,
1584 .write_wakeup = n_tty_write_wakeup
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585};
1586