blob: 708c2b1dbe51068a5d1b91ba27d38d79d0c39308 [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{
Alan Cox39c2e602008-04-30 00:54:18 -0700150 if (tty->count)
151 tty_unthrottle(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152}
153
154/**
155 * reset_buffer_flags - reset buffer state
156 * @tty: terminal to reset
157 *
Alan Cox4edf1822008-02-08 04:18:44 -0800158 * Reset the read buffer counters, clear the flags,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 * and make sure the driver is unthrottled. Called
160 * from n_tty_open() and n_tty_flush_buffer().
161 */
162static void reset_buffer_flags(struct tty_struct *tty)
163{
164 unsigned long flags;
165
166 spin_lock_irqsave(&tty->read_lock, flags);
167 tty->read_head = tty->read_tail = tty->read_cnt = 0;
168 spin_unlock_irqrestore(&tty->read_lock, flags);
169 tty->canon_head = tty->canon_data = tty->erasing = 0;
170 memset(&tty->read_flags, 0, sizeof tty->read_flags);
Alan Cox33f0f882006-01-09 20:54:13 -0800171 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 check_unthrottle(tty);
173}
174
175/**
176 * n_tty_flush_buffer - clean input queue
177 * @tty: terminal device
178 *
179 * Flush the input buffer. Called when the line discipline is
180 * being closed, when the tty layer wants the buffer flushed (eg
181 * at hangup) or when the N_TTY line discipline internally has to
182 * clean the pending queue (for example some signals).
183 *
Alan Cox04f378b2008-04-30 00:53:29 -0700184 * Locking: ctrl_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 */
Alan Cox4edf1822008-02-08 04:18:44 -0800186
187static void n_tty_flush_buffer(struct tty_struct *tty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188{
Alan Cox04f378b2008-04-30 00:53:29 -0700189 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 /* clear everything and unthrottle the driver */
191 reset_buffer_flags(tty);
Alan Cox4edf1822008-02-08 04:18:44 -0800192
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 if (!tty->link)
194 return;
195
Alan Cox04f378b2008-04-30 00:53:29 -0700196 spin_lock_irqsave(&tty->ctrl_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 if (tty->link->packet) {
198 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
199 wake_up_interruptible(&tty->link->read_wait);
200 }
Alan Cox04f378b2008-04-30 00:53:29 -0700201 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202}
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
Alan Cox04f378b2008-04-30 00:53:29 -0700267 * re-entrantly. Relies on lock_kernel() for tty->column state.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 */
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
Alan Coxf34d7a52008-04-30 00:54:13 -0700274 space = tty_write_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 if (!space)
276 return -1;
277
Alan Cox04f378b2008-04-30 00:53:29 -0700278 lock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 if (O_OPOST(tty)) {
280 switch (c) {
281 case '\n':
282 if (O_ONLRET(tty))
283 tty->column = 0;
284 if (O_ONLCR(tty)) {
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200285 if (space < 2) {
286 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 return -1;
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200288 }
Alan Coxf34d7a52008-04-30 00:54:13 -0700289 tty_put_char(tty, '\r');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 tty->column = 0;
291 }
292 tty->canon_column = tty->column;
293 break;
294 case '\r':
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200295 if (O_ONOCR(tty) && tty->column == 0) {
296 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 return 0;
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200298 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 if (O_OCRNL(tty)) {
300 c = '\n';
301 if (O_ONLRET(tty))
302 tty->canon_column = tty->column = 0;
303 break;
304 }
305 tty->canon_column = tty->column = 0;
306 break;
307 case '\t':
308 spaces = 8 - (tty->column & 7);
309 if (O_TABDLY(tty) == XTABS) {
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200310 if (space < spaces) {
311 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 return -1;
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200313 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 tty->column += spaces;
Alan Coxf34d7a52008-04-30 00:54:13 -0700315 tty->ops->write(tty, " ", spaces);
Ingo Molnar487ad7e2008-05-14 17:11:46 +0200316 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 return 0;
318 }
319 tty->column += spaces;
320 break;
321 case '\b':
322 if (tty->column > 0)
323 tty->column--;
324 break;
325 default:
326 if (O_OLCUC(tty))
327 c = toupper(c);
328 if (!iscntrl(c) && !is_continuation(c, tty))
329 tty->column++;
330 break;
331 }
332 }
Alan Coxf34d7a52008-04-30 00:54:13 -0700333 tty_put_char(tty, c);
Alan Cox04f378b2008-04-30 00:53:29 -0700334 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 return 0;
336}
337
338/**
339 * opost_block - block postprocess
340 * @tty: terminal device
341 * @inbuf: user buffer
342 * @nr: number of bytes
343 *
344 * This path is used to speed up block console writes, among other
345 * things when processing blocks of output data. It handles only
346 * the simple cases normally found and helps to generate blocks of
347 * symbols for the console driver and thus improve performance.
348 *
Alan Cox04f378b2008-04-30 00:53:29 -0700349 * Called from write_chan under the tty layer write lock. Relies
350 * on lock_kernel for the tty->column state.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 */
Alan Cox4edf1822008-02-08 04:18:44 -0800352
353static ssize_t opost_block(struct tty_struct *tty,
354 const unsigned char *buf, unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355{
356 int space;
357 int i;
358 const unsigned char *cp;
359
Alan Coxf34d7a52008-04-30 00:54:13 -0700360 space = tty_write_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 if (!space)
362 return 0;
363 if (nr > space)
364 nr = space;
365
Alan Cox04f378b2008-04-30 00:53:29 -0700366 lock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 for (i = 0, cp = buf; i < nr; i++, cp++) {
368 switch (*cp) {
369 case '\n':
370 if (O_ONLRET(tty))
371 tty->column = 0;
372 if (O_ONLCR(tty))
373 goto break_out;
374 tty->canon_column = tty->column;
375 break;
376 case '\r':
377 if (O_ONOCR(tty) && tty->column == 0)
378 goto break_out;
379 if (O_OCRNL(tty))
380 goto break_out;
381 tty->canon_column = tty->column = 0;
382 break;
383 case '\t':
384 goto break_out;
385 case '\b':
386 if (tty->column > 0)
387 tty->column--;
388 break;
389 default:
390 if (O_OLCUC(tty))
391 goto break_out;
392 if (!iscntrl(*cp))
393 tty->column++;
394 break;
395 }
396 }
397break_out:
Alan Coxf34d7a52008-04-30 00:54:13 -0700398 if (tty->ops->flush_chars)
399 tty->ops->flush_chars(tty);
400 i = tty->ops->write(tty, buf, i);
Alan Cox04f378b2008-04-30 00:53:29 -0700401 unlock_kernel();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 return i;
403}
404
405
406/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 * echo_char - echo characters
408 * @c: unicode byte to echo
409 * @tty: terminal device
410 *
Alan Cox4edf1822008-02-08 04:18:44 -0800411 * Echo user input back onto the screen. This must be called only when
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 * L_ECHO(tty) is true. Called from the driver receive_buf path.
413 */
414
415static void echo_char(unsigned char c, struct tty_struct *tty)
416{
417 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
Alan Coxf34d7a52008-04-30 00:54:13 -0700418 tty_put_char(tty, '^');
419 tty_put_char(tty, c ^ 0100);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 tty->column += 2;
421 } else
422 opost(c, tty);
423}
424
425static inline void finish_erasing(struct tty_struct *tty)
426{
427 if (tty->erasing) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700428 tty_put_char(tty, '/');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 tty->column++;
430 tty->erasing = 0;
431 }
432}
433
434/**
435 * eraser - handle erase function
436 * @c: character input
437 * @tty: terminal device
438 *
Robert P. J. Day3a4fa0a2007-10-19 23:10:43 +0200439 * Perform erase and necessary output when an erase character is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 * present in the stream from the driver layer. Handles the complexities
441 * of UTF-8 multibyte symbols.
442 */
Alan Cox4edf1822008-02-08 04:18:44 -0800443
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444static void eraser(unsigned char c, struct tty_struct *tty)
445{
446 enum { ERASE, WERASE, KILL } kill_type;
447 int head, seen_alnums, cnt;
448 unsigned long flags;
449
450 if (tty->read_head == tty->canon_head) {
451 /* opost('\a', tty); */ /* what do you think? */
452 return;
453 }
454 if (c == ERASE_CHAR(tty))
455 kill_type = ERASE;
456 else if (c == WERASE_CHAR(tty))
457 kill_type = WERASE;
458 else {
459 if (!L_ECHO(tty)) {
460 spin_lock_irqsave(&tty->read_lock, flags);
461 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
462 (N_TTY_BUF_SIZE - 1));
463 tty->read_head = tty->canon_head;
464 spin_unlock_irqrestore(&tty->read_lock, flags);
465 return;
466 }
467 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
468 spin_lock_irqsave(&tty->read_lock, flags);
469 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
470 (N_TTY_BUF_SIZE - 1));
471 tty->read_head = tty->canon_head;
472 spin_unlock_irqrestore(&tty->read_lock, flags);
473 finish_erasing(tty);
474 echo_char(KILL_CHAR(tty), tty);
475 /* Add a newline if ECHOK is on and ECHOKE is off. */
476 if (L_ECHOK(tty))
477 opost('\n', tty);
478 return;
479 }
480 kill_type = KILL;
481 }
482
483 seen_alnums = 0;
484 while (tty->read_head != tty->canon_head) {
485 head = tty->read_head;
486
487 /* erase a single possibly multibyte character */
488 do {
489 head = (head - 1) & (N_TTY_BUF_SIZE-1);
490 c = tty->read_buf[head];
491 } while (is_continuation(c, tty) && head != tty->canon_head);
492
493 /* do not partially erase */
494 if (is_continuation(c, tty))
495 break;
496
497 if (kill_type == WERASE) {
498 /* Equivalent to BSD's ALTWERASE. */
499 if (isalnum(c) || c == '_')
500 seen_alnums++;
501 else if (seen_alnums)
502 break;
503 }
504 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
505 spin_lock_irqsave(&tty->read_lock, flags);
506 tty->read_head = head;
507 tty->read_cnt -= cnt;
508 spin_unlock_irqrestore(&tty->read_lock, flags);
509 if (L_ECHO(tty)) {
510 if (L_ECHOPRT(tty)) {
511 if (!tty->erasing) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700512 tty_put_char(tty, '\\');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 tty->column++;
514 tty->erasing = 1;
515 }
516 /* if cnt > 1, output a multi-byte character */
517 echo_char(c, tty);
518 while (--cnt > 0) {
519 head = (head+1) & (N_TTY_BUF_SIZE-1);
Alan Coxf34d7a52008-04-30 00:54:13 -0700520 tty_put_char(tty, tty->read_buf[head]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 }
522 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
523 echo_char(ERASE_CHAR(tty), tty);
524 } else if (c == '\t') {
525 unsigned int col = tty->canon_column;
526 unsigned long tail = tty->canon_head;
527
528 /* Find the column of the last char. */
529 while (tail != tty->read_head) {
530 c = tty->read_buf[tail];
531 if (c == '\t')
532 col = (col | 7) + 1;
533 else if (iscntrl(c)) {
534 if (L_ECHOCTL(tty))
535 col += 2;
536 } else if (!is_continuation(c, tty))
537 col++;
538 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
539 }
540
541 /* should never happen */
542 if (tty->column > 0x80000000)
Alan Cox4edf1822008-02-08 04:18:44 -0800543 tty->column = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544
545 /* Now backup to that column. */
546 while (tty->column > col) {
547 /* Can't use opost here. */
Alan Coxf34d7a52008-04-30 00:54:13 -0700548 tty_put_char(tty, '\b');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 if (tty->column > 0)
550 tty->column--;
551 }
552 } else {
553 if (iscntrl(c) && L_ECHOCTL(tty)) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700554 tty_put_char(tty, '\b');
555 tty_put_char(tty, ' ');
556 tty_put_char(tty, '\b');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557 if (tty->column > 0)
558 tty->column--;
559 }
560 if (!iscntrl(c) || L_ECHOCTL(tty)) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700561 tty_put_char(tty, '\b');
562 tty_put_char(tty, ' ');
563 tty_put_char(tty, '\b');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 if (tty->column > 0)
565 tty->column--;
566 }
567 }
568 }
569 if (kill_type == ERASE)
570 break;
571 }
572 if (tty->read_head == tty->canon_head)
573 finish_erasing(tty);
574}
575
576/**
577 * isig - handle the ISIG optio
578 * @sig: signal
579 * @tty: terminal
580 * @flush: force flush
581 *
582 * Called when a signal is being sent due to terminal input. This
583 * may caus terminal flushing to take place according to the termios
584 * settings and character used. Called from the driver receive_buf
585 * path so serialized.
586 */
Alan Cox4edf1822008-02-08 04:18:44 -0800587
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588static inline void isig(int sig, struct tty_struct *tty, int flush)
589{
Eric W. Biedermanab521dc2007-02-12 00:53:00 -0800590 if (tty->pgrp)
591 kill_pgrp(tty->pgrp, sig, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 if (flush || !L_NOFLSH(tty)) {
593 n_tty_flush_buffer(tty);
Alan Coxf34d7a52008-04-30 00:54:13 -0700594 tty_driver_flush_buffer(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 }
596}
597
598/**
599 * n_tty_receive_break - handle break
600 * @tty: terminal
601 *
602 * An RS232 break event has been hit in the incoming bitstream. This
603 * can cause a variety of events depending upon the termios settings.
604 *
605 * Called from the receive_buf path so single threaded.
606 */
Alan Cox4edf1822008-02-08 04:18:44 -0800607
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608static inline void n_tty_receive_break(struct tty_struct *tty)
609{
610 if (I_IGNBRK(tty))
611 return;
612 if (I_BRKINT(tty)) {
613 isig(SIGINT, tty, 1);
614 return;
615 }
616 if (I_PARMRK(tty)) {
617 put_tty_queue('\377', tty);
618 put_tty_queue('\0', tty);
619 }
620 put_tty_queue('\0', tty);
621 wake_up_interruptible(&tty->read_wait);
622}
623
624/**
625 * n_tty_receive_overrun - handle overrun reporting
626 * @tty: terminal
627 *
628 * Data arrived faster than we could process it. While the tty
629 * driver has flagged this the bits that were missed are gone
630 * forever.
631 *
632 * Called from the receive_buf path so single threaded. Does not
633 * need locking as num_overrun and overrun_time are function
634 * private.
635 */
Alan Cox4edf1822008-02-08 04:18:44 -0800636
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637static inline void n_tty_receive_overrun(struct tty_struct *tty)
638{
639 char buf[64];
640
641 tty->num_overrun++;
642 if (time_before(tty->overrun_time, jiffies - HZ) ||
643 time_after(tty->overrun_time, jiffies)) {
644 printk(KERN_WARNING "%s: %d input overrun(s)\n",
645 tty_name(tty, buf),
646 tty->num_overrun);
647 tty->overrun_time = jiffies;
648 tty->num_overrun = 0;
649 }
650}
651
652/**
653 * n_tty_receive_parity_error - error notifier
654 * @tty: terminal device
655 * @c: character
656 *
657 * Process a parity error and queue the right data to indicate
Robert P. J. Day3a4fa0a2007-10-19 23:10:43 +0200658 * the error case if necessary. Locking as per n_tty_receive_buf.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 */
660static inline void n_tty_receive_parity_error(struct tty_struct *tty,
661 unsigned char c)
662{
Alan Cox4edf1822008-02-08 04:18:44 -0800663 if (I_IGNPAR(tty))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 if (I_PARMRK(tty)) {
666 put_tty_queue('\377', tty);
667 put_tty_queue('\0', tty);
668 put_tty_queue(c, tty);
669 } else if (I_INPCK(tty))
670 put_tty_queue('\0', tty);
671 else
672 put_tty_queue(c, tty);
673 wake_up_interruptible(&tty->read_wait);
674}
675
676/**
677 * n_tty_receive_char - perform processing
678 * @tty: terminal device
679 * @c: character
680 *
681 * Process an individual character of input received from the driver.
Alan Cox4edf1822008-02-08 04:18:44 -0800682 * This is serialized with respect to itself by the rules for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 * driver above.
684 */
685
686static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
687{
688 unsigned long flags;
689
690 if (tty->raw) {
691 put_tty_queue(c, tty);
692 return;
693 }
Alan Cox4edf1822008-02-08 04:18:44 -0800694
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 if (I_ISTRIP(tty))
696 c &= 0x7f;
697 if (I_IUCLC(tty) && L_IEXTEN(tty))
698 c=tolower(c);
699
Joe Peterson54d2a372008-02-06 01:37:59 -0800700 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
701 ((I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty)) ||
Joe Peterson575537b2008-04-30 00:53:30 -0700702 c == INTR_CHAR(tty) || c == QUIT_CHAR(tty) || c == SUSP_CHAR(tty)))
Joe Peterson54d2a372008-02-06 01:37:59 -0800703 start_tty(tty);
704
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 if (tty->closing) {
706 if (I_IXON(tty)) {
707 if (c == START_CHAR(tty))
708 start_tty(tty);
709 else if (c == STOP_CHAR(tty))
710 stop_tty(tty);
711 }
712 return;
713 }
714
715 /*
716 * If the previous character was LNEXT, or we know that this
717 * character is not one of the characters that we'll have to
718 * handle specially, do shortcut processing to speed things
719 * up.
720 */
721 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
722 finish_erasing(tty);
723 tty->lnext = 0;
724 if (L_ECHO(tty)) {
725 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700726 tty_put_char(tty, '\a'); /* beep if no space */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 return;
728 }
729 /* Record the column of first canon char. */
730 if (tty->canon_head == tty->read_head)
731 tty->canon_column = tty->column;
732 echo_char(c, tty);
733 }
734 if (I_PARMRK(tty) && c == (unsigned char) '\377')
735 put_tty_queue(c, tty);
736 put_tty_queue(c, tty);
737 return;
738 }
Alan Cox4edf1822008-02-08 04:18:44 -0800739
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 if (I_IXON(tty)) {
741 if (c == START_CHAR(tty)) {
742 start_tty(tty);
743 return;
744 }
745 if (c == STOP_CHAR(tty)) {
746 stop_tty(tty);
747 return;
748 }
749 }
Joe Peterson575537b2008-04-30 00:53:30 -0700750
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 if (L_ISIG(tty)) {
752 int signal;
753 signal = SIGINT;
754 if (c == INTR_CHAR(tty))
755 goto send_signal;
756 signal = SIGQUIT;
757 if (c == QUIT_CHAR(tty))
758 goto send_signal;
759 signal = SIGTSTP;
760 if (c == SUSP_CHAR(tty)) {
761send_signal:
Joe Petersonec5b1152008-02-06 01:37:38 -0800762 /*
763 * Echo character, and then send the signal.
764 * Note that we do not use isig() here because we want
765 * the order to be:
766 * 1) flush, 2) echo, 3) signal
767 */
768 if (!L_NOFLSH(tty)) {
769 n_tty_flush_buffer(tty);
Alan Coxf34d7a52008-04-30 00:54:13 -0700770 tty_driver_flush_buffer(tty);
Joe Petersonec5b1152008-02-06 01:37:38 -0800771 }
772 if (L_ECHO(tty))
773 echo_char(c, tty);
774 if (tty->pgrp)
775 kill_pgrp(tty->pgrp, signal, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 return;
777 }
778 }
Joe Peterson575537b2008-04-30 00:53:30 -0700779
780 if (c == '\r') {
781 if (I_IGNCR(tty))
782 return;
783 if (I_ICRNL(tty))
784 c = '\n';
785 } else if (c == '\n' && I_INLCR(tty))
786 c = '\r';
787
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 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)) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700799 tty_put_char(tty, '^');
800 tty_put_char(tty, '\b');
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 }
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)
Alan Coxf34d7a52008-04-30 00:54:13 -0700821 tty_put_char(tty, '\a');
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)
Alan Coxf34d7a52008-04-30 00:54:13 -0700839 tty_put_char(tty, '\a');
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) {
Alan Coxf34d7a52008-04-30 00:54:13 -0700869 tty_put_char(tty, '\a'); /* beep if no space */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 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 }
Alan Coxf34d7a52008-04-30 00:54:13 -0700973 if (tty->ops->flush_chars)
974 tty->ops->flush_chars(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 }
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 Cox39c2e602008-04-30 00:54:18 -0700990 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
991 tty_throttle(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992}
993
994int is_ignored(int sig)
995{
996 return (sigismember(&current->blocked, sig) ||
Alan Cox4edf1822008-02-08 04:18:44 -0800997 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998}
999
1000/**
1001 * n_tty_set_termios - termios data changed
1002 * @tty: terminal
1003 * @old: previous data
1004 *
1005 * Called by the tty layer when the user changes termios flags so
1006 * that the line discipline can plan ahead. This function cannot sleep
Alan Cox4edf1822008-02-08 04:18:44 -08001007 * and is protected from re-entry by the tty layer. The user is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008 * guaranteed that this function will not be re-entered or in progress
1009 * when the ldisc is closed.
1010 */
Alan Cox4edf1822008-02-08 04:18:44 -08001011
1012static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013{
1014 if (!tty)
1015 return;
Alan Cox4edf1822008-02-08 04:18:44 -08001016
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 tty->icanon = (L_ICANON(tty) != 0);
1018 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1019 tty->raw = 1;
1020 tty->real_raw = 1;
Alan Cox33f0f882006-01-09 20:54:13 -08001021 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 return;
1023 }
1024 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1025 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1026 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1027 I_PARMRK(tty)) {
1028 memset(tty->process_char_map, 0, 256/8);
1029
1030 if (I_IGNCR(tty) || I_ICRNL(tty))
1031 set_bit('\r', tty->process_char_map);
1032 if (I_INLCR(tty))
1033 set_bit('\n', tty->process_char_map);
1034
1035 if (L_ICANON(tty)) {
1036 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1037 set_bit(KILL_CHAR(tty), tty->process_char_map);
1038 set_bit(EOF_CHAR(tty), tty->process_char_map);
1039 set_bit('\n', tty->process_char_map);
1040 set_bit(EOL_CHAR(tty), tty->process_char_map);
1041 if (L_IEXTEN(tty)) {
1042 set_bit(WERASE_CHAR(tty),
1043 tty->process_char_map);
1044 set_bit(LNEXT_CHAR(tty),
1045 tty->process_char_map);
1046 set_bit(EOL2_CHAR(tty),
1047 tty->process_char_map);
1048 if (L_ECHO(tty))
1049 set_bit(REPRINT_CHAR(tty),
1050 tty->process_char_map);
1051 }
1052 }
1053 if (I_IXON(tty)) {
1054 set_bit(START_CHAR(tty), tty->process_char_map);
1055 set_bit(STOP_CHAR(tty), tty->process_char_map);
1056 }
1057 if (L_ISIG(tty)) {
1058 set_bit(INTR_CHAR(tty), tty->process_char_map);
1059 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1060 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1061 }
1062 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1063 tty->raw = 0;
1064 tty->real_raw = 0;
1065 } else {
1066 tty->raw = 1;
1067 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1068 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1069 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1070 tty->real_raw = 1;
1071 else
1072 tty->real_raw = 0;
1073 }
Alan Cox33f0f882006-01-09 20:54:13 -08001074 n_tty_set_room(tty);
Alan Coxf34d7a52008-04-30 00:54:13 -07001075 /* The termios change make the tty ready for I/O */
1076 wake_up_interruptible(&tty->write_wait);
1077 wake_up_interruptible(&tty->read_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078}
1079
1080/**
1081 * n_tty_close - close the ldisc for this tty
1082 * @tty: device
1083 *
Alan Cox4edf1822008-02-08 04:18:44 -08001084 * Called from the terminal layer when this line discipline is
1085 * being shut down, either because of a close or becsuse of a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086 * discipline change. The function will not be called while other
1087 * ldisc methods are in progress.
1088 */
Alan Cox4edf1822008-02-08 04:18:44 -08001089
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090static void n_tty_close(struct tty_struct *tty)
1091{
1092 n_tty_flush_buffer(tty);
1093 if (tty->read_buf) {
1094 free_buf(tty->read_buf);
1095 tty->read_buf = NULL;
1096 }
1097}
1098
1099/**
1100 * n_tty_open - open an ldisc
1101 * @tty: terminal to open
1102 *
Alan Cox4edf1822008-02-08 04:18:44 -08001103 * Called when this line discipline is being attached to the
Linus Torvalds1da177e2005-04-16 15:20:36 -07001104 * terminal device. Can sleep. Called serialized so that no
1105 * other events will occur in parallel. No further open will occur
1106 * until a close.
1107 */
1108
1109static int n_tty_open(struct tty_struct *tty)
1110{
1111 if (!tty)
1112 return -EINVAL;
1113
1114 /* This one is ugly. Currently a malloc failure here can panic */
1115 if (!tty->read_buf) {
1116 tty->read_buf = alloc_buf();
1117 if (!tty->read_buf)
1118 return -ENOMEM;
1119 }
1120 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1121 reset_buffer_flags(tty);
1122 tty->column = 0;
1123 n_tty_set_termios(tty, NULL);
1124 tty->minimum_to_wake = 1;
1125 tty->closing = 0;
1126 return 0;
1127}
1128
1129static inline int input_available_p(struct tty_struct *tty, int amt)
1130{
1131 if (tty->icanon) {
1132 if (tty->canon_data)
1133 return 1;
1134 } else if (tty->read_cnt >= (amt ? amt : 1))
1135 return 1;
1136
1137 return 0;
1138}
1139
1140/**
1141 * copy_from_read_buf - copy read data directly
1142 * @tty: terminal device
1143 * @b: user data
1144 * @nr: size of data
1145 *
1146 * Helper function to speed up read_chan. It is only called when
1147 * ICANON is off; it copies characters straight from the tty queue to
1148 * user space directly. It can be profitably called twice; once to
1149 * drain the space from the tail pointer to the (physical) end of the
1150 * buffer, and once to drain the space from the (physical) beginning of
1151 * the buffer to head pointer.
1152 *
Paul Fulghum817d6d32006-06-28 04:26:47 -07001153 * Called under the tty->atomic_read_lock sem
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154 *
1155 */
Alan Cox4edf1822008-02-08 04:18:44 -08001156
Alan Cox33f0f882006-01-09 20:54:13 -08001157static int copy_from_read_buf(struct tty_struct *tty,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 unsigned char __user **b,
1159 size_t *nr)
1160
1161{
1162 int retval;
1163 size_t n;
1164 unsigned long flags;
1165
1166 retval = 0;
1167 spin_lock_irqsave(&tty->read_lock, flags);
1168 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1169 n = min(*nr, n);
1170 spin_unlock_irqrestore(&tty->read_lock, flags);
1171 if (n) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1173 n -= retval;
Miloslav Trmac522ed772007-07-15 23:40:56 -07001174 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 spin_lock_irqsave(&tty->read_lock, flags);
1176 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1177 tty->read_cnt -= n;
1178 spin_unlock_irqrestore(&tty->read_lock, flags);
1179 *b += n;
1180 *nr -= n;
1181 }
1182 return retval;
1183}
1184
Al Virocc4191d2008-03-29 03:08:48 +00001185extern ssize_t redirected_tty_write(struct file *, const char __user *,
Alan Cox4edf1822008-02-08 04:18:44 -08001186 size_t, loff_t *);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187
1188/**
1189 * job_control - check job control
1190 * @tty: tty
1191 * @file: file handle
1192 *
1193 * Perform job control management checks on this file/tty descriptor
Alan Cox4edf1822008-02-08 04:18:44 -08001194 * and if appropriate send any needed signals and return a negative
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 * error code if action should be taken.
Alan Cox04f378b2008-04-30 00:53:29 -07001196 *
1197 * FIXME:
1198 * Locking: None - redirected write test is safe, testing
1199 * current->signal should possibly lock current->sighand
1200 * pgrp locking ?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 */
Alan Cox4edf1822008-02-08 04:18:44 -08001202
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203static int job_control(struct tty_struct *tty, struct file *file)
1204{
1205 /* Job control check -- must be done at start and after
1206 every sleep (POSIX.1 7.1.1.4). */
1207 /* NOTE: not yet done after every sleep pending a thorough
1208 check of the logic of this change. -- jlc */
1209 /* don't stop on /dev/console */
1210 if (file->f_op->write != redirected_tty_write &&
1211 current->signal->tty == tty) {
Eric W. Biedermanab521dc2007-02-12 00:53:00 -08001212 if (!tty->pgrp)
Alan Cox4edf1822008-02-08 04:18:44 -08001213 printk(KERN_ERR "read_chan: no tty->pgrp!\n");
Eric W. Biedermanab521dc2007-02-12 00:53:00 -08001214 else if (task_pgrp(current) != tty->pgrp) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 if (is_ignored(SIGTTIN) ||
Eric W. Biederman3e7cd6c2007-02-12 00:52:58 -08001216 is_current_pgrp_orphaned())
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217 return -EIO;
Eric W. Biedermanab521dc2007-02-12 00:53:00 -08001218 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
Oleg Nesterov040b6362007-06-01 00:46:53 -07001219 set_thread_flag(TIF_SIGPENDING);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 return -ERESTARTSYS;
1221 }
1222 }
1223 return 0;
1224}
Alan Cox4edf1822008-02-08 04:18:44 -08001225
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226
1227/**
1228 * read_chan - read function for tty
1229 * @tty: tty device
1230 * @file: file object
1231 * @buf: userspace buffer pointer
1232 * @nr: size of I/O
1233 *
1234 * Perform reads for the line discipline. We are guaranteed that the
1235 * line discipline will not be closed under us but we may get multiple
1236 * parallel readers and must handle this ourselves. We may also get
1237 * a hangup. Always called in user context, may sleep.
1238 *
1239 * This code must be sure never to sleep through a hangup.
1240 */
Alan Cox4edf1822008-02-08 04:18:44 -08001241
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242static ssize_t read_chan(struct tty_struct *tty, struct file *file,
1243 unsigned char __user *buf, size_t nr)
1244{
1245 unsigned char __user *b = buf;
1246 DECLARE_WAITQUEUE(wait, current);
1247 int c;
1248 int minimum, time;
1249 ssize_t retval = 0;
1250 ssize_t size;
1251 long timeout;
1252 unsigned long flags;
Alan Cox04f378b2008-04-30 00:53:29 -07001253 int packet;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254
1255do_it_again:
1256
1257 if (!tty->read_buf) {
Alan Cox4edf1822008-02-08 04:18:44 -08001258 printk(KERN_ERR "n_tty_read_chan: read_buf == NULL?!?\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259 return -EIO;
1260 }
1261
1262 c = job_control(tty, file);
Alan Cox4edf1822008-02-08 04:18:44 -08001263 if (c < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 return c;
Alan Cox4edf1822008-02-08 04:18:44 -08001265
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266 minimum = time = 0;
1267 timeout = MAX_SCHEDULE_TIMEOUT;
1268 if (!tty->icanon) {
1269 time = (HZ / 10) * TIME_CHAR(tty);
1270 minimum = MIN_CHAR(tty);
1271 if (minimum) {
1272 if (time)
1273 tty->minimum_to_wake = 1;
1274 else if (!waitqueue_active(&tty->read_wait) ||
1275 (tty->minimum_to_wake > minimum))
1276 tty->minimum_to_wake = minimum;
1277 } else {
1278 timeout = 0;
1279 if (time) {
1280 timeout = time;
1281 time = 0;
1282 }
1283 tty->minimum_to_wake = minimum = 1;
1284 }
1285 }
1286
1287 /*
1288 * Internal serialization of reads.
1289 */
1290 if (file->f_flags & O_NONBLOCK) {
Ingo Molnar70522e12006-03-23 03:00:31 -08001291 if (!mutex_trylock(&tty->atomic_read_lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292 return -EAGAIN;
Alan Cox4edf1822008-02-08 04:18:44 -08001293 } else {
Ingo Molnar70522e12006-03-23 03:00:31 -08001294 if (mutex_lock_interruptible(&tty->atomic_read_lock))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 return -ERESTARTSYS;
1296 }
Alan Cox04f378b2008-04-30 00:53:29 -07001297 packet = tty->packet;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298
1299 add_wait_queue(&tty->read_wait, &wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 while (nr) {
1301 /* First test for status change. */
Alan Cox04f378b2008-04-30 00:53:29 -07001302 if (packet && tty->link->ctrl_status) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 unsigned char cs;
1304 if (b != buf)
1305 break;
Alan Cox04f378b2008-04-30 00:53:29 -07001306 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 cs = tty->link->ctrl_status;
1308 tty->link->ctrl_status = 0;
Alan Cox04f378b2008-04-30 00:53:29 -07001309 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
Miloslav Trmac522ed772007-07-15 23:40:56 -07001310 if (tty_put_user(tty, cs, b++)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 retval = -EFAULT;
1312 b--;
1313 break;
1314 }
1315 nr--;
1316 break;
1317 }
1318 /* This statement must be first before checking for input
1319 so that any interrupt will set the state back to
1320 TASK_RUNNING. */
1321 set_current_state(TASK_INTERRUPTIBLE);
Alan Cox4edf1822008-02-08 04:18:44 -08001322
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1324 ((minimum - (b - buf)) >= 1))
1325 tty->minimum_to_wake = (minimum - (b - buf));
Alan Cox4edf1822008-02-08 04:18:44 -08001326
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 if (!input_available_p(tty, 0)) {
1328 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1329 retval = -EIO;
1330 break;
1331 }
1332 if (tty_hung_up_p(file))
1333 break;
1334 if (!timeout)
1335 break;
1336 if (file->f_flags & O_NONBLOCK) {
1337 retval = -EAGAIN;
1338 break;
1339 }
1340 if (signal_pending(current)) {
1341 retval = -ERESTARTSYS;
1342 break;
1343 }
Alan Cox04f378b2008-04-30 00:53:29 -07001344 /* FIXME: does n_tty_set_room need locking ? */
Alan Cox33f0f882006-01-09 20:54:13 -08001345 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 timeout = schedule_timeout(timeout);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 continue;
1348 }
1349 __set_current_state(TASK_RUNNING);
1350
1351 /* Deal with packet mode. */
Alan Cox04f378b2008-04-30 00:53:29 -07001352 if (packet && b == buf) {
Miloslav Trmac522ed772007-07-15 23:40:56 -07001353 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 retval = -EFAULT;
1355 b--;
1356 break;
1357 }
1358 nr--;
1359 }
1360
1361 if (tty->icanon) {
1362 /* N.B. avoid overrun if nr == 0 */
1363 while (nr && tty->read_cnt) {
Alan Cox4edf1822008-02-08 04:18:44 -08001364 int eol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365
1366 eol = test_and_clear_bit(tty->read_tail,
1367 tty->read_flags);
1368 c = tty->read_buf[tty->read_tail];
1369 spin_lock_irqsave(&tty->read_lock, flags);
1370 tty->read_tail = ((tty->read_tail+1) &
1371 (N_TTY_BUF_SIZE-1));
1372 tty->read_cnt--;
1373 if (eol) {
1374 /* this test should be redundant:
1375 * we shouldn't be reading data if
1376 * canon_data is 0
1377 */
1378 if (--tty->canon_data < 0)
1379 tty->canon_data = 0;
1380 }
1381 spin_unlock_irqrestore(&tty->read_lock, flags);
1382
1383 if (!eol || (c != __DISABLED_CHAR)) {
Miloslav Trmac522ed772007-07-15 23:40:56 -07001384 if (tty_put_user(tty, c, b++)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 retval = -EFAULT;
1386 b--;
1387 break;
1388 }
1389 nr--;
1390 }
Miloslav Trmac522ed772007-07-15 23:40:56 -07001391 if (eol) {
1392 tty_audit_push(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 break;
Miloslav Trmac522ed772007-07-15 23:40:56 -07001394 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 }
1396 if (retval)
1397 break;
1398 } else {
1399 int uncopied;
Alan Cox04f378b2008-04-30 00:53:29 -07001400 /* The copy function takes the read lock and handles
1401 locking internally for this case */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 uncopied = copy_from_read_buf(tty, &b, &nr);
1403 uncopied += copy_from_read_buf(tty, &b, &nr);
1404 if (uncopied) {
1405 retval = -EFAULT;
1406 break;
1407 }
1408 }
1409
1410 /* If there is enough space in the read buffer now, let the
1411 * low-level driver know. We use n_tty_chars_in_buffer() to
1412 * check the buffer, as it now knows about canonical mode.
1413 * Otherwise, if the driver is throttled and the line is
1414 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1415 * we won't get any more characters.
1416 */
Paul Mackerras289a1e92006-06-12 12:16:26 +10001417 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1418 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 check_unthrottle(tty);
Paul Mackerras289a1e92006-06-12 12:16:26 +10001420 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
1422 if (b - buf >= minimum)
1423 break;
1424 if (time)
1425 timeout = time;
1426 }
Ingo Molnar70522e12006-03-23 03:00:31 -08001427 mutex_unlock(&tty->atomic_read_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 remove_wait_queue(&tty->read_wait, &wait);
1429
1430 if (!waitqueue_active(&tty->read_wait))
1431 tty->minimum_to_wake = minimum;
1432
1433 __set_current_state(TASK_RUNNING);
1434 size = b - buf;
1435 if (size) {
1436 retval = size;
1437 if (nr)
Alan Cox4edf1822008-02-08 04:18:44 -08001438 clear_bit(TTY_PUSH, &tty->flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1440 goto do_it_again;
1441
Alan Cox33f0f882006-01-09 20:54:13 -08001442 n_tty_set_room(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 return retval;
1444}
1445
1446/**
1447 * write_chan - write function for tty
1448 * @tty: tty device
1449 * @file: file object
1450 * @buf: userspace buffer pointer
1451 * @nr: size of I/O
1452 *
1453 * Write function of the terminal device. This is serialized with
1454 * respect to other write callers but not to termios changes, reads
1455 * and other such events. We must be careful with N_TTY as the receive
1456 * code will echo characters, thus calling driver write methods.
1457 *
1458 * This code must be sure never to sleep through a hangup.
1459 */
Alan Cox4edf1822008-02-08 04:18:44 -08001460
1461static ssize_t write_chan(struct tty_struct *tty, struct file *file,
1462 const unsigned char *buf, size_t nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463{
1464 const unsigned char *b = buf;
1465 DECLARE_WAITQUEUE(wait, current);
1466 int c;
1467 ssize_t retval = 0;
1468
1469 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1470 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1471 retval = tty_check_change(tty);
1472 if (retval)
1473 return retval;
1474 }
1475
1476 add_wait_queue(&tty->write_wait, &wait);
1477 while (1) {
1478 set_current_state(TASK_INTERRUPTIBLE);
1479 if (signal_pending(current)) {
1480 retval = -ERESTARTSYS;
1481 break;
1482 }
1483 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1484 retval = -EIO;
1485 break;
1486 }
1487 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1488 while (nr > 0) {
1489 ssize_t num = opost_block(tty, b, nr);
1490 if (num < 0) {
1491 if (num == -EAGAIN)
1492 break;
1493 retval = num;
1494 goto break_out;
1495 }
1496 b += num;
1497 nr -= num;
1498 if (nr == 0)
1499 break;
1500 c = *b;
1501 if (opost(c, tty) < 0)
1502 break;
1503 b++; nr--;
1504 }
Alan Coxf34d7a52008-04-30 00:54:13 -07001505 if (tty->ops->flush_chars)
1506 tty->ops->flush_chars(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 } else {
Roman Zippeld6afe272005-07-07 17:56:55 -07001508 while (nr > 0) {
Alan Coxf34d7a52008-04-30 00:54:13 -07001509 c = tty->ops->write(tty, b, nr);
Roman Zippeld6afe272005-07-07 17:56:55 -07001510 if (c < 0) {
1511 retval = c;
1512 goto break_out;
1513 }
1514 if (!c)
1515 break;
1516 b += c;
1517 nr -= c;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 }
1520 if (!nr)
1521 break;
1522 if (file->f_flags & O_NONBLOCK) {
1523 retval = -EAGAIN;
1524 break;
1525 }
1526 schedule();
1527 }
1528break_out:
1529 __set_current_state(TASK_RUNNING);
1530 remove_wait_queue(&tty->write_wait, &wait);
1531 return (b - buf) ? b - buf : retval;
1532}
1533
1534/**
1535 * normal_poll - poll method for N_TTY
1536 * @tty: terminal device
1537 * @file: file accessing it
1538 * @wait: poll table
1539 *
1540 * Called when the line discipline is asked to poll() for data or
1541 * for special events. This code is not serialized with respect to
1542 * other events save open/close.
1543 *
1544 * This code must be sure never to sleep through a hangup.
1545 * Called without the kernel lock held - fine
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 */
Alan Cox4edf1822008-02-08 04:18:44 -08001547
1548static unsigned int normal_poll(struct tty_struct *tty, struct file *file,
1549 poll_table *wait)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550{
1551 unsigned int mask = 0;
1552
1553 poll_wait(file, &tty->read_wait, wait);
1554 poll_wait(file, &tty->write_wait, wait);
1555 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1556 mask |= POLLIN | POLLRDNORM;
1557 if (tty->packet && tty->link->ctrl_status)
1558 mask |= POLLPRI | POLLIN | POLLRDNORM;
1559 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1560 mask |= POLLHUP;
1561 if (tty_hung_up_p(file))
1562 mask |= POLLHUP;
1563 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1564 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1565 tty->minimum_to_wake = MIN_CHAR(tty);
1566 else
1567 tty->minimum_to_wake = 1;
1568 }
Alan Coxf34d7a52008-04-30 00:54:13 -07001569 if (tty->ops->write && !tty_is_writelocked(tty) &&
1570 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
1571 tty_write_room(tty) > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572 mask |= POLLOUT | POLLWRNORM;
1573 return mask;
1574}
1575
Alan Coxa352def2008-07-16 21:53:12 +01001576struct tty_ldisc_ops tty_ldisc_N_TTY = {
Paul Fulghume10cc1d2007-05-10 22:22:50 -07001577 .magic = TTY_LDISC_MAGIC,
1578 .name = "n_tty",
1579 .open = n_tty_open,
1580 .close = n_tty_close,
1581 .flush_buffer = n_tty_flush_buffer,
1582 .chars_in_buffer = n_tty_chars_in_buffer,
1583 .read = read_chan,
1584 .write = write_chan,
1585 .ioctl = n_tty_ioctl,
1586 .set_termios = n_tty_set_termios,
1587 .poll = normal_poll,
1588 .receive_buf = n_tty_receive_buf,
1589 .write_wakeup = n_tty_write_wakeup
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590};
1591