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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * n_tty.c --- implements the N_TTY line discipline. | |
3 | * | |
4 | * 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 | |
11 | * to N_TTY if it can not switch to any other line discipline. | |
12 | * | |
13 | * Written by Theodore Ts'o, Copyright 1994. | |
14 | * | |
15 | * This file also contains code originally written by Linus Torvalds, | |
16 | * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994. | |
17 | * | |
18 | * 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 | * | |
23 | * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of | |
24 | * 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> | |
48 | ||
49 | #include <asm/uaccess.h> | |
50 | #include <asm/system.h> | |
51 | ||
52 | /* number of characters left in xmit buffer before select has we have room */ | |
53 | #define WAKEUP_CHARS 256 | |
54 | ||
55 | /* | |
56 | * This defines the low- and high-watermarks for throttling and | |
57 | * unthrottling the TTY driver. These watermarks are used for | |
58 | * controlling the space in the read buffer. | |
59 | */ | |
60 | #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ | |
61 | #define TTY_THRESHOLD_UNTHROTTLE 128 | |
62 | ||
63 | static inline unsigned char *alloc_buf(void) | |
64 | { | |
b4e3ca1a | 65 | gfp_t prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL; |
1da177e4 LT |
66 | |
67 | if (PAGE_SIZE != N_TTY_BUF_SIZE) | |
68 | return kmalloc(N_TTY_BUF_SIZE, prio); | |
69 | else | |
70 | return (unsigned char *)__get_free_page(prio); | |
71 | } | |
72 | ||
73 | static inline void free_buf(unsigned char *buf) | |
74 | { | |
75 | if (PAGE_SIZE != N_TTY_BUF_SIZE) | |
76 | kfree(buf); | |
77 | else | |
78 | free_page((unsigned long) buf); | |
79 | } | |
80 | ||
33f0f88f AC |
81 | /** |
82 | * n_tty_set__room - receive space | |
83 | * @tty: terminal | |
84 | * | |
85 | * Called by the driver to find out how much data it is | |
86 | * permitted to feed to the line discipline without any being lost | |
87 | * and thus to manage flow control. Not serialized. Answers for the | |
88 | * "instant". | |
89 | */ | |
90 | ||
91 | static void n_tty_set_room(struct tty_struct *tty) | |
92 | { | |
93 | int left = N_TTY_BUF_SIZE - tty->read_cnt - 1; | |
94 | ||
95 | /* | |
96 | * If we are doing input canonicalization, and there are no | |
97 | * pending newlines, let characters through without limit, so | |
98 | * that erase characters will be handled. Other excess | |
99 | * characters will be beeped. | |
100 | */ | |
101 | if (left <= 0) | |
102 | left = tty->icanon && !tty->canon_data; | |
103 | tty->receive_room = left; | |
104 | } | |
105 | ||
106 | static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty) | |
1da177e4 LT |
107 | { |
108 | if (tty->read_cnt < N_TTY_BUF_SIZE) { | |
109 | tty->read_buf[tty->read_head] = c; | |
110 | tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1); | |
111 | tty->read_cnt++; | |
112 | } | |
113 | } | |
114 | ||
33f0f88f | 115 | static void put_tty_queue(unsigned char c, struct tty_struct *tty) |
1da177e4 LT |
116 | { |
117 | unsigned long flags; | |
118 | /* | |
119 | * The problem of stomping on the buffers ends here. | |
120 | * Why didn't anyone see this one coming? --AJK | |
121 | */ | |
122 | spin_lock_irqsave(&tty->read_lock, flags); | |
123 | put_tty_queue_nolock(c, tty); | |
124 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
125 | } | |
126 | ||
127 | /** | |
128 | * check_unthrottle - allow new receive data | |
129 | * @tty; tty device | |
130 | * | |
131 | * Check whether to call the driver.unthrottle function. | |
132 | * We test the TTY_THROTTLED bit first so that it always | |
133 | * indicates the current state. The decision about whether | |
134 | * it is worth allowing more input has been taken by the caller. | |
70522e12 | 135 | * Can sleep, may be called under the atomic_read_lock mutex but |
1da177e4 LT |
136 | * this is not guaranteed. |
137 | */ | |
138 | ||
139 | static void check_unthrottle(struct tty_struct * tty) | |
140 | { | |
141 | if (tty->count && | |
142 | test_and_clear_bit(TTY_THROTTLED, &tty->flags) && | |
143 | tty->driver->unthrottle) | |
144 | tty->driver->unthrottle(tty); | |
145 | } | |
146 | ||
147 | /** | |
148 | * reset_buffer_flags - reset buffer state | |
149 | * @tty: terminal to reset | |
150 | * | |
151 | * Reset the read buffer counters, clear the flags, | |
152 | * and make sure the driver is unthrottled. Called | |
153 | * from n_tty_open() and n_tty_flush_buffer(). | |
154 | */ | |
155 | static void reset_buffer_flags(struct tty_struct *tty) | |
156 | { | |
157 | unsigned long flags; | |
158 | ||
159 | spin_lock_irqsave(&tty->read_lock, flags); | |
160 | tty->read_head = tty->read_tail = tty->read_cnt = 0; | |
161 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
162 | tty->canon_head = tty->canon_data = tty->erasing = 0; | |
163 | memset(&tty->read_flags, 0, sizeof tty->read_flags); | |
33f0f88f | 164 | n_tty_set_room(tty); |
1da177e4 LT |
165 | check_unthrottle(tty); |
166 | } | |
167 | ||
168 | /** | |
169 | * n_tty_flush_buffer - clean input queue | |
170 | * @tty: terminal device | |
171 | * | |
172 | * Flush the input buffer. Called when the line discipline is | |
173 | * being closed, when the tty layer wants the buffer flushed (eg | |
174 | * at hangup) or when the N_TTY line discipline internally has to | |
175 | * clean the pending queue (for example some signals). | |
176 | * | |
177 | * FIXME: tty->ctrl_status is not spinlocked and relies on | |
178 | * lock_kernel() still. | |
179 | */ | |
180 | ||
181 | static void n_tty_flush_buffer(struct tty_struct * tty) | |
182 | { | |
183 | /* clear everything and unthrottle the driver */ | |
184 | reset_buffer_flags(tty); | |
185 | ||
186 | if (!tty->link) | |
187 | return; | |
188 | ||
189 | if (tty->link->packet) { | |
190 | tty->ctrl_status |= TIOCPKT_FLUSHREAD; | |
191 | wake_up_interruptible(&tty->link->read_wait); | |
192 | } | |
193 | } | |
194 | ||
195 | /** | |
196 | * n_tty_chars_in_buffer - report available bytes | |
197 | * @tty: tty device | |
198 | * | |
199 | * Report the number of characters buffered to be delivered to user | |
200 | * at this instant in time. | |
201 | */ | |
202 | ||
203 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) | |
204 | { | |
205 | unsigned long flags; | |
206 | ssize_t n = 0; | |
207 | ||
208 | spin_lock_irqsave(&tty->read_lock, flags); | |
209 | if (!tty->icanon) { | |
210 | n = tty->read_cnt; | |
211 | } else if (tty->canon_data) { | |
212 | n = (tty->canon_head > tty->read_tail) ? | |
213 | tty->canon_head - tty->read_tail : | |
214 | tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail); | |
215 | } | |
216 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
217 | return n; | |
218 | } | |
219 | ||
220 | /** | |
221 | * is_utf8_continuation - utf8 multibyte check | |
222 | * @c: byte to check | |
223 | * | |
224 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
225 | * character. We use this to correctly compute the on screen size | |
226 | * of the character when printing | |
227 | */ | |
228 | ||
229 | static inline int is_utf8_continuation(unsigned char c) | |
230 | { | |
231 | return (c & 0xc0) == 0x80; | |
232 | } | |
233 | ||
234 | /** | |
235 | * is_continuation - multibyte check | |
236 | * @c: byte to check | |
237 | * | |
238 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
239 | * character and the terminal is in unicode mode. | |
240 | */ | |
241 | ||
242 | static inline int is_continuation(unsigned char c, struct tty_struct *tty) | |
243 | { | |
244 | return I_IUTF8(tty) && is_utf8_continuation(c); | |
245 | } | |
246 | ||
247 | /** | |
248 | * opost - output post processor | |
249 | * @c: character (or partial unicode symbol) | |
250 | * @tty: terminal device | |
251 | * | |
252 | * Perform OPOST processing. Returns -1 when the output device is | |
253 | * full and the character must be retried. Note that Linux currently | |
254 | * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't | |
255 | * relevant in the world today. If you ever need them, add them here. | |
256 | * | |
257 | * Called from both the receive and transmit sides and can be called | |
258 | * re-entrantly. Relies on lock_kernel() still. | |
259 | */ | |
260 | ||
261 | static int opost(unsigned char c, struct tty_struct *tty) | |
262 | { | |
263 | int space, spaces; | |
264 | ||
265 | space = tty->driver->write_room(tty); | |
266 | if (!space) | |
267 | return -1; | |
268 | ||
269 | if (O_OPOST(tty)) { | |
270 | switch (c) { | |
271 | case '\n': | |
272 | if (O_ONLRET(tty)) | |
273 | tty->column = 0; | |
274 | if (O_ONLCR(tty)) { | |
275 | if (space < 2) | |
276 | return -1; | |
277 | tty->driver->put_char(tty, '\r'); | |
278 | tty->column = 0; | |
279 | } | |
280 | tty->canon_column = tty->column; | |
281 | break; | |
282 | case '\r': | |
283 | if (O_ONOCR(tty) && tty->column == 0) | |
284 | return 0; | |
285 | if (O_OCRNL(tty)) { | |
286 | c = '\n'; | |
287 | if (O_ONLRET(tty)) | |
288 | tty->canon_column = tty->column = 0; | |
289 | break; | |
290 | } | |
291 | tty->canon_column = tty->column = 0; | |
292 | break; | |
293 | case '\t': | |
294 | spaces = 8 - (tty->column & 7); | |
295 | if (O_TABDLY(tty) == XTABS) { | |
296 | if (space < spaces) | |
297 | return -1; | |
298 | tty->column += spaces; | |
299 | tty->driver->write(tty, " ", spaces); | |
300 | return 0; | |
301 | } | |
302 | tty->column += spaces; | |
303 | break; | |
304 | case '\b': | |
305 | if (tty->column > 0) | |
306 | tty->column--; | |
307 | break; | |
308 | default: | |
309 | if (O_OLCUC(tty)) | |
310 | c = toupper(c); | |
311 | if (!iscntrl(c) && !is_continuation(c, tty)) | |
312 | tty->column++; | |
313 | break; | |
314 | } | |
315 | } | |
316 | tty->driver->put_char(tty, c); | |
317 | return 0; | |
318 | } | |
319 | ||
320 | /** | |
321 | * opost_block - block postprocess | |
322 | * @tty: terminal device | |
323 | * @inbuf: user buffer | |
324 | * @nr: number of bytes | |
325 | * | |
326 | * This path is used to speed up block console writes, among other | |
327 | * things when processing blocks of output data. It handles only | |
328 | * the simple cases normally found and helps to generate blocks of | |
329 | * symbols for the console driver and thus improve performance. | |
330 | * | |
331 | * Called from write_chan under the tty layer write lock. | |
332 | */ | |
333 | ||
334 | static ssize_t opost_block(struct tty_struct * tty, | |
335 | const unsigned char * buf, unsigned int nr) | |
336 | { | |
337 | int space; | |
338 | int i; | |
339 | const unsigned char *cp; | |
340 | ||
341 | space = tty->driver->write_room(tty); | |
342 | if (!space) | |
343 | return 0; | |
344 | if (nr > space) | |
345 | nr = space; | |
346 | ||
347 | for (i = 0, cp = buf; i < nr; i++, cp++) { | |
348 | switch (*cp) { | |
349 | case '\n': | |
350 | if (O_ONLRET(tty)) | |
351 | tty->column = 0; | |
352 | if (O_ONLCR(tty)) | |
353 | goto break_out; | |
354 | tty->canon_column = tty->column; | |
355 | break; | |
356 | case '\r': | |
357 | if (O_ONOCR(tty) && tty->column == 0) | |
358 | goto break_out; | |
359 | if (O_OCRNL(tty)) | |
360 | goto break_out; | |
361 | tty->canon_column = tty->column = 0; | |
362 | break; | |
363 | case '\t': | |
364 | goto break_out; | |
365 | case '\b': | |
366 | if (tty->column > 0) | |
367 | tty->column--; | |
368 | break; | |
369 | default: | |
370 | if (O_OLCUC(tty)) | |
371 | goto break_out; | |
372 | if (!iscntrl(*cp)) | |
373 | tty->column++; | |
374 | break; | |
375 | } | |
376 | } | |
377 | break_out: | |
378 | if (tty->driver->flush_chars) | |
379 | tty->driver->flush_chars(tty); | |
380 | i = tty->driver->write(tty, buf, i); | |
381 | return i; | |
382 | } | |
383 | ||
384 | ||
385 | /** | |
386 | * put_char - write character to driver | |
387 | * @c: character (or part of unicode symbol) | |
388 | * @tty: terminal device | |
389 | * | |
390 | * Queue a byte to the driver layer for output | |
391 | */ | |
392 | ||
393 | static inline void put_char(unsigned char c, struct tty_struct *tty) | |
394 | { | |
395 | tty->driver->put_char(tty, c); | |
396 | } | |
397 | ||
398 | /** | |
399 | * echo_char - echo characters | |
400 | * @c: unicode byte to echo | |
401 | * @tty: terminal device | |
402 | * | |
403 | * Echo user input back onto the screen. This must be called only when | |
404 | * L_ECHO(tty) is true. Called from the driver receive_buf path. | |
405 | */ | |
406 | ||
407 | static void echo_char(unsigned char c, struct tty_struct *tty) | |
408 | { | |
409 | if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') { | |
410 | put_char('^', tty); | |
411 | put_char(c ^ 0100, tty); | |
412 | tty->column += 2; | |
413 | } else | |
414 | opost(c, tty); | |
415 | } | |
416 | ||
417 | static inline void finish_erasing(struct tty_struct *tty) | |
418 | { | |
419 | if (tty->erasing) { | |
420 | put_char('/', tty); | |
421 | tty->column++; | |
422 | tty->erasing = 0; | |
423 | } | |
424 | } | |
425 | ||
426 | /** | |
427 | * eraser - handle erase function | |
428 | * @c: character input | |
429 | * @tty: terminal device | |
430 | * | |
431 | * Perform erase and neccessary output when an erase character is | |
432 | * present in the stream from the driver layer. Handles the complexities | |
433 | * of UTF-8 multibyte symbols. | |
434 | */ | |
435 | ||
436 | static void eraser(unsigned char c, struct tty_struct *tty) | |
437 | { | |
438 | enum { ERASE, WERASE, KILL } kill_type; | |
439 | int head, seen_alnums, cnt; | |
440 | unsigned long flags; | |
441 | ||
442 | if (tty->read_head == tty->canon_head) { | |
443 | /* opost('\a', tty); */ /* what do you think? */ | |
444 | return; | |
445 | } | |
446 | if (c == ERASE_CHAR(tty)) | |
447 | kill_type = ERASE; | |
448 | else if (c == WERASE_CHAR(tty)) | |
449 | kill_type = WERASE; | |
450 | else { | |
451 | if (!L_ECHO(tty)) { | |
452 | spin_lock_irqsave(&tty->read_lock, flags); | |
453 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & | |
454 | (N_TTY_BUF_SIZE - 1)); | |
455 | tty->read_head = tty->canon_head; | |
456 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
457 | return; | |
458 | } | |
459 | if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(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 | finish_erasing(tty); | |
466 | echo_char(KILL_CHAR(tty), tty); | |
467 | /* Add a newline if ECHOK is on and ECHOKE is off. */ | |
468 | if (L_ECHOK(tty)) | |
469 | opost('\n', tty); | |
470 | return; | |
471 | } | |
472 | kill_type = KILL; | |
473 | } | |
474 | ||
475 | seen_alnums = 0; | |
476 | while (tty->read_head != tty->canon_head) { | |
477 | head = tty->read_head; | |
478 | ||
479 | /* erase a single possibly multibyte character */ | |
480 | do { | |
481 | head = (head - 1) & (N_TTY_BUF_SIZE-1); | |
482 | c = tty->read_buf[head]; | |
483 | } while (is_continuation(c, tty) && head != tty->canon_head); | |
484 | ||
485 | /* do not partially erase */ | |
486 | if (is_continuation(c, tty)) | |
487 | break; | |
488 | ||
489 | if (kill_type == WERASE) { | |
490 | /* Equivalent to BSD's ALTWERASE. */ | |
491 | if (isalnum(c) || c == '_') | |
492 | seen_alnums++; | |
493 | else if (seen_alnums) | |
494 | break; | |
495 | } | |
496 | cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1); | |
497 | spin_lock_irqsave(&tty->read_lock, flags); | |
498 | tty->read_head = head; | |
499 | tty->read_cnt -= cnt; | |
500 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
501 | if (L_ECHO(tty)) { | |
502 | if (L_ECHOPRT(tty)) { | |
503 | if (!tty->erasing) { | |
504 | put_char('\\', tty); | |
505 | tty->column++; | |
506 | tty->erasing = 1; | |
507 | } | |
508 | /* if cnt > 1, output a multi-byte character */ | |
509 | echo_char(c, tty); | |
510 | while (--cnt > 0) { | |
511 | head = (head+1) & (N_TTY_BUF_SIZE-1); | |
512 | put_char(tty->read_buf[head], tty); | |
513 | } | |
514 | } else if (kill_type == ERASE && !L_ECHOE(tty)) { | |
515 | echo_char(ERASE_CHAR(tty), tty); | |
516 | } else if (c == '\t') { | |
517 | unsigned int col = tty->canon_column; | |
518 | unsigned long tail = tty->canon_head; | |
519 | ||
520 | /* Find the column of the last char. */ | |
521 | while (tail != tty->read_head) { | |
522 | c = tty->read_buf[tail]; | |
523 | if (c == '\t') | |
524 | col = (col | 7) + 1; | |
525 | else if (iscntrl(c)) { | |
526 | if (L_ECHOCTL(tty)) | |
527 | col += 2; | |
528 | } else if (!is_continuation(c, tty)) | |
529 | col++; | |
530 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); | |
531 | } | |
532 | ||
533 | /* should never happen */ | |
534 | if (tty->column > 0x80000000) | |
535 | tty->column = 0; | |
536 | ||
537 | /* Now backup to that column. */ | |
538 | while (tty->column > col) { | |
539 | /* Can't use opost here. */ | |
540 | put_char('\b', tty); | |
541 | if (tty->column > 0) | |
542 | tty->column--; | |
543 | } | |
544 | } else { | |
545 | if (iscntrl(c) && L_ECHOCTL(tty)) { | |
546 | put_char('\b', tty); | |
547 | put_char(' ', tty); | |
548 | put_char('\b', tty); | |
549 | if (tty->column > 0) | |
550 | tty->column--; | |
551 | } | |
552 | if (!iscntrl(c) || L_ECHOCTL(tty)) { | |
553 | put_char('\b', tty); | |
554 | put_char(' ', tty); | |
555 | put_char('\b', tty); | |
556 | if (tty->column > 0) | |
557 | tty->column--; | |
558 | } | |
559 | } | |
560 | } | |
561 | if (kill_type == ERASE) | |
562 | break; | |
563 | } | |
564 | if (tty->read_head == tty->canon_head) | |
565 | finish_erasing(tty); | |
566 | } | |
567 | ||
568 | /** | |
569 | * isig - handle the ISIG optio | |
570 | * @sig: signal | |
571 | * @tty: terminal | |
572 | * @flush: force flush | |
573 | * | |
574 | * Called when a signal is being sent due to terminal input. This | |
575 | * may caus terminal flushing to take place according to the termios | |
576 | * settings and character used. Called from the driver receive_buf | |
577 | * path so serialized. | |
578 | */ | |
579 | ||
580 | static inline void isig(int sig, struct tty_struct *tty, int flush) | |
581 | { | |
582 | if (tty->pgrp > 0) | |
583 | kill_pg(tty->pgrp, sig, 1); | |
584 | if (flush || !L_NOFLSH(tty)) { | |
585 | n_tty_flush_buffer(tty); | |
586 | if (tty->driver->flush_buffer) | |
587 | tty->driver->flush_buffer(tty); | |
588 | } | |
589 | } | |
590 | ||
591 | /** | |
592 | * n_tty_receive_break - handle break | |
593 | * @tty: terminal | |
594 | * | |
595 | * An RS232 break event has been hit in the incoming bitstream. This | |
596 | * can cause a variety of events depending upon the termios settings. | |
597 | * | |
598 | * Called from the receive_buf path so single threaded. | |
599 | */ | |
600 | ||
601 | static inline void n_tty_receive_break(struct tty_struct *tty) | |
602 | { | |
603 | if (I_IGNBRK(tty)) | |
604 | return; | |
605 | if (I_BRKINT(tty)) { | |
606 | isig(SIGINT, tty, 1); | |
607 | return; | |
608 | } | |
609 | if (I_PARMRK(tty)) { | |
610 | put_tty_queue('\377', tty); | |
611 | put_tty_queue('\0', tty); | |
612 | } | |
613 | put_tty_queue('\0', tty); | |
614 | wake_up_interruptible(&tty->read_wait); | |
615 | } | |
616 | ||
617 | /** | |
618 | * n_tty_receive_overrun - handle overrun reporting | |
619 | * @tty: terminal | |
620 | * | |
621 | * Data arrived faster than we could process it. While the tty | |
622 | * driver has flagged this the bits that were missed are gone | |
623 | * forever. | |
624 | * | |
625 | * Called from the receive_buf path so single threaded. Does not | |
626 | * need locking as num_overrun and overrun_time are function | |
627 | * private. | |
628 | */ | |
629 | ||
630 | static inline void n_tty_receive_overrun(struct tty_struct *tty) | |
631 | { | |
632 | char buf[64]; | |
633 | ||
634 | tty->num_overrun++; | |
635 | if (time_before(tty->overrun_time, jiffies - HZ) || | |
636 | time_after(tty->overrun_time, jiffies)) { | |
637 | printk(KERN_WARNING "%s: %d input overrun(s)\n", | |
638 | tty_name(tty, buf), | |
639 | tty->num_overrun); | |
640 | tty->overrun_time = jiffies; | |
641 | tty->num_overrun = 0; | |
642 | } | |
643 | } | |
644 | ||
645 | /** | |
646 | * n_tty_receive_parity_error - error notifier | |
647 | * @tty: terminal device | |
648 | * @c: character | |
649 | * | |
650 | * Process a parity error and queue the right data to indicate | |
651 | * the error case if neccessary. Locking as per n_tty_receive_buf. | |
652 | */ | |
653 | static inline void n_tty_receive_parity_error(struct tty_struct *tty, | |
654 | unsigned char c) | |
655 | { | |
656 | if (I_IGNPAR(tty)) { | |
657 | return; | |
658 | } | |
659 | if (I_PARMRK(tty)) { | |
660 | put_tty_queue('\377', tty); | |
661 | put_tty_queue('\0', tty); | |
662 | put_tty_queue(c, tty); | |
663 | } else if (I_INPCK(tty)) | |
664 | put_tty_queue('\0', tty); | |
665 | else | |
666 | put_tty_queue(c, tty); | |
667 | wake_up_interruptible(&tty->read_wait); | |
668 | } | |
669 | ||
670 | /** | |
671 | * n_tty_receive_char - perform processing | |
672 | * @tty: terminal device | |
673 | * @c: character | |
674 | * | |
675 | * Process an individual character of input received from the driver. | |
676 | * This is serialized with respect to itself by the rules for the | |
677 | * driver above. | |
678 | */ | |
679 | ||
680 | static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) | |
681 | { | |
682 | unsigned long flags; | |
683 | ||
684 | if (tty->raw) { | |
685 | put_tty_queue(c, tty); | |
686 | return; | |
687 | } | |
688 | ||
689 | if (tty->stopped && !tty->flow_stopped && | |
690 | I_IXON(tty) && I_IXANY(tty)) { | |
691 | start_tty(tty); | |
692 | return; | |
693 | } | |
694 | ||
695 | if (I_ISTRIP(tty)) | |
696 | c &= 0x7f; | |
697 | if (I_IUCLC(tty) && L_IEXTEN(tty)) | |
698 | c=tolower(c); | |
699 | ||
700 | if (tty->closing) { | |
701 | if (I_IXON(tty)) { | |
702 | if (c == START_CHAR(tty)) | |
703 | start_tty(tty); | |
704 | else if (c == STOP_CHAR(tty)) | |
705 | stop_tty(tty); | |
706 | } | |
707 | return; | |
708 | } | |
709 | ||
710 | /* | |
711 | * If the previous character was LNEXT, or we know that this | |
712 | * character is not one of the characters that we'll have to | |
713 | * handle specially, do shortcut processing to speed things | |
714 | * up. | |
715 | */ | |
716 | if (!test_bit(c, tty->process_char_map) || tty->lnext) { | |
717 | finish_erasing(tty); | |
718 | tty->lnext = 0; | |
719 | if (L_ECHO(tty)) { | |
720 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { | |
721 | put_char('\a', tty); /* beep if no space */ | |
722 | return; | |
723 | } | |
724 | /* Record the column of first canon char. */ | |
725 | if (tty->canon_head == tty->read_head) | |
726 | tty->canon_column = tty->column; | |
727 | echo_char(c, tty); | |
728 | } | |
729 | if (I_PARMRK(tty) && c == (unsigned char) '\377') | |
730 | put_tty_queue(c, tty); | |
731 | put_tty_queue(c, tty); | |
732 | return; | |
733 | } | |
734 | ||
735 | if (c == '\r') { | |
736 | if (I_IGNCR(tty)) | |
737 | return; | |
738 | if (I_ICRNL(tty)) | |
739 | c = '\n'; | |
740 | } else if (c == '\n' && I_INLCR(tty)) | |
741 | c = '\r'; | |
742 | if (I_IXON(tty)) { | |
743 | if (c == START_CHAR(tty)) { | |
744 | start_tty(tty); | |
745 | return; | |
746 | } | |
747 | if (c == STOP_CHAR(tty)) { | |
748 | stop_tty(tty); | |
749 | return; | |
750 | } | |
751 | } | |
752 | if (L_ISIG(tty)) { | |
753 | int signal; | |
754 | signal = SIGINT; | |
755 | if (c == INTR_CHAR(tty)) | |
756 | goto send_signal; | |
757 | signal = SIGQUIT; | |
758 | if (c == QUIT_CHAR(tty)) | |
759 | goto send_signal; | |
760 | signal = SIGTSTP; | |
761 | if (c == SUSP_CHAR(tty)) { | |
762 | send_signal: | |
763 | isig(signal, tty, 0); | |
764 | return; | |
765 | } | |
766 | } | |
767 | if (tty->icanon) { | |
768 | if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || | |
769 | (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { | |
770 | eraser(c, tty); | |
771 | return; | |
772 | } | |
773 | if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { | |
774 | tty->lnext = 1; | |
775 | if (L_ECHO(tty)) { | |
776 | finish_erasing(tty); | |
777 | if (L_ECHOCTL(tty)) { | |
778 | put_char('^', tty); | |
779 | put_char('\b', tty); | |
780 | } | |
781 | } | |
782 | return; | |
783 | } | |
784 | if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && | |
785 | L_IEXTEN(tty)) { | |
786 | unsigned long tail = tty->canon_head; | |
787 | ||
788 | finish_erasing(tty); | |
789 | echo_char(c, tty); | |
790 | opost('\n', tty); | |
791 | while (tail != tty->read_head) { | |
792 | echo_char(tty->read_buf[tail], tty); | |
793 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); | |
794 | } | |
795 | return; | |
796 | } | |
797 | if (c == '\n') { | |
798 | if (L_ECHO(tty) || L_ECHONL(tty)) { | |
d6afe27b | 799 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) |
1da177e4 | 800 | put_char('\a', tty); |
1da177e4 LT |
801 | opost('\n', tty); |
802 | } | |
803 | goto handle_newline; | |
804 | } | |
805 | if (c == EOF_CHAR(tty)) { | |
806 | if (tty->canon_head != tty->read_head) | |
807 | set_bit(TTY_PUSH, &tty->flags); | |
808 | c = __DISABLED_CHAR; | |
809 | goto handle_newline; | |
810 | } | |
811 | if ((c == EOL_CHAR(tty)) || | |
812 | (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { | |
813 | /* | |
814 | * XXX are EOL_CHAR and EOL2_CHAR echoed?!? | |
815 | */ | |
816 | if (L_ECHO(tty)) { | |
d6afe27b | 817 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) |
1da177e4 | 818 | put_char('\a', tty); |
1da177e4 LT |
819 | /* Record the column of first canon char. */ |
820 | if (tty->canon_head == tty->read_head) | |
821 | tty->canon_column = tty->column; | |
822 | echo_char(c, tty); | |
823 | } | |
824 | /* | |
825 | * XXX does PARMRK doubling happen for | |
826 | * EOL_CHAR and EOL2_CHAR? | |
827 | */ | |
828 | if (I_PARMRK(tty) && c == (unsigned char) '\377') | |
829 | put_tty_queue(c, tty); | |
830 | ||
831 | handle_newline: | |
832 | spin_lock_irqsave(&tty->read_lock, flags); | |
833 | set_bit(tty->read_head, tty->read_flags); | |
834 | put_tty_queue_nolock(c, tty); | |
835 | tty->canon_head = tty->read_head; | |
836 | tty->canon_data++; | |
837 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
838 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
839 | if (waitqueue_active(&tty->read_wait)) | |
840 | wake_up_interruptible(&tty->read_wait); | |
841 | return; | |
842 | } | |
843 | } | |
844 | ||
845 | finish_erasing(tty); | |
846 | if (L_ECHO(tty)) { | |
847 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { | |
848 | put_char('\a', tty); /* beep if no space */ | |
849 | return; | |
850 | } | |
851 | if (c == '\n') | |
852 | opost('\n', tty); | |
853 | else { | |
854 | /* Record the column of first canon char. */ | |
855 | if (tty->canon_head == tty->read_head) | |
856 | tty->canon_column = tty->column; | |
857 | echo_char(c, tty); | |
858 | } | |
859 | } | |
860 | ||
861 | if (I_PARMRK(tty) && c == (unsigned char) '\377') | |
862 | put_tty_queue(c, tty); | |
863 | ||
864 | put_tty_queue(c, tty); | |
865 | } | |
866 | ||
1da177e4 LT |
867 | |
868 | /** | |
869 | * n_tty_write_wakeup - asynchronous I/O notifier | |
870 | * @tty: tty device | |
871 | * | |
872 | * Required for the ptys, serial driver etc. since processes | |
873 | * that attach themselves to the master and rely on ASYNC | |
874 | * IO must be woken up | |
875 | */ | |
876 | ||
877 | static void n_tty_write_wakeup(struct tty_struct *tty) | |
878 | { | |
879 | if (tty->fasync) | |
880 | { | |
881 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
882 | kill_fasync(&tty->fasync, SIGIO, POLL_OUT); | |
883 | } | |
884 | return; | |
885 | } | |
886 | ||
887 | /** | |
888 | * n_tty_receive_buf - data receive | |
889 | * @tty: terminal device | |
890 | * @cp: buffer | |
891 | * @fp: flag buffer | |
892 | * @count: characters | |
893 | * | |
894 | * Called by the terminal driver when a block of characters has | |
895 | * been received. This function must be called from soft contexts | |
896 | * not from interrupt context. The driver is responsible for making | |
897 | * calls one at a time and in order (or using flush_to_ldisc) | |
898 | */ | |
899 | ||
900 | static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, | |
901 | char *fp, int count) | |
902 | { | |
903 | const unsigned char *p; | |
904 | char *f, flags = TTY_NORMAL; | |
905 | int i; | |
906 | char buf[64]; | |
907 | unsigned long cpuflags; | |
908 | ||
909 | if (!tty->read_buf) | |
910 | return; | |
911 | ||
912 | if (tty->real_raw) { | |
913 | spin_lock_irqsave(&tty->read_lock, cpuflags); | |
914 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, | |
915 | N_TTY_BUF_SIZE - tty->read_head); | |
916 | i = min(count, i); | |
917 | memcpy(tty->read_buf + tty->read_head, cp, i); | |
918 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); | |
919 | tty->read_cnt += i; | |
920 | cp += i; | |
921 | count -= i; | |
922 | ||
923 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, | |
924 | N_TTY_BUF_SIZE - tty->read_head); | |
925 | i = min(count, i); | |
926 | memcpy(tty->read_buf + tty->read_head, cp, i); | |
927 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); | |
928 | tty->read_cnt += i; | |
929 | spin_unlock_irqrestore(&tty->read_lock, cpuflags); | |
930 | } else { | |
931 | for (i=count, p = cp, f = fp; i; i--, p++) { | |
932 | if (f) | |
933 | flags = *f++; | |
934 | switch (flags) { | |
935 | case TTY_NORMAL: | |
936 | n_tty_receive_char(tty, *p); | |
937 | break; | |
938 | case TTY_BREAK: | |
939 | n_tty_receive_break(tty); | |
940 | break; | |
941 | case TTY_PARITY: | |
942 | case TTY_FRAME: | |
943 | n_tty_receive_parity_error(tty, *p); | |
944 | break; | |
945 | case TTY_OVERRUN: | |
946 | n_tty_receive_overrun(tty); | |
947 | break; | |
948 | default: | |
949 | printk("%s: unknown flag %d\n", | |
950 | tty_name(tty, buf), flags); | |
951 | break; | |
952 | } | |
953 | } | |
954 | if (tty->driver->flush_chars) | |
955 | tty->driver->flush_chars(tty); | |
956 | } | |
957 | ||
33f0f88f AC |
958 | n_tty_set_room(tty); |
959 | ||
1da177e4 LT |
960 | if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) { |
961 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
962 | if (waitqueue_active(&tty->read_wait)) | |
963 | wake_up_interruptible(&tty->read_wait); | |
964 | } | |
965 | ||
966 | /* | |
967 | * Check the remaining room for the input canonicalization | |
968 | * mode. We don't want to throttle the driver if we're in | |
969 | * canonical mode and don't have a newline yet! | |
970 | */ | |
33f0f88f | 971 | if (tty->receive_room < TTY_THRESHOLD_THROTTLE) { |
1da177e4 LT |
972 | /* check TTY_THROTTLED first so it indicates our state */ |
973 | if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) && | |
974 | tty->driver->throttle) | |
975 | tty->driver->throttle(tty); | |
976 | } | |
977 | } | |
978 | ||
979 | int is_ignored(int sig) | |
980 | { | |
981 | return (sigismember(¤t->blocked, sig) || | |
982 | current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); | |
983 | } | |
984 | ||
985 | /** | |
986 | * n_tty_set_termios - termios data changed | |
987 | * @tty: terminal | |
988 | * @old: previous data | |
989 | * | |
990 | * Called by the tty layer when the user changes termios flags so | |
991 | * that the line discipline can plan ahead. This function cannot sleep | |
992 | * and is protected from re-entry by the tty layer. The user is | |
993 | * guaranteed that this function will not be re-entered or in progress | |
994 | * when the ldisc is closed. | |
995 | */ | |
996 | ||
997 | static void n_tty_set_termios(struct tty_struct *tty, struct termios * old) | |
998 | { | |
999 | if (!tty) | |
1000 | return; | |
1001 | ||
1002 | tty->icanon = (L_ICANON(tty) != 0); | |
1003 | if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { | |
1004 | tty->raw = 1; | |
1005 | tty->real_raw = 1; | |
33f0f88f | 1006 | n_tty_set_room(tty); |
1da177e4 LT |
1007 | return; |
1008 | } | |
1009 | if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || | |
1010 | I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || | |
1011 | I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || | |
1012 | I_PARMRK(tty)) { | |
1013 | memset(tty->process_char_map, 0, 256/8); | |
1014 | ||
1015 | if (I_IGNCR(tty) || I_ICRNL(tty)) | |
1016 | set_bit('\r', tty->process_char_map); | |
1017 | if (I_INLCR(tty)) | |
1018 | set_bit('\n', tty->process_char_map); | |
1019 | ||
1020 | if (L_ICANON(tty)) { | |
1021 | set_bit(ERASE_CHAR(tty), tty->process_char_map); | |
1022 | set_bit(KILL_CHAR(tty), tty->process_char_map); | |
1023 | set_bit(EOF_CHAR(tty), tty->process_char_map); | |
1024 | set_bit('\n', tty->process_char_map); | |
1025 | set_bit(EOL_CHAR(tty), tty->process_char_map); | |
1026 | if (L_IEXTEN(tty)) { | |
1027 | set_bit(WERASE_CHAR(tty), | |
1028 | tty->process_char_map); | |
1029 | set_bit(LNEXT_CHAR(tty), | |
1030 | tty->process_char_map); | |
1031 | set_bit(EOL2_CHAR(tty), | |
1032 | tty->process_char_map); | |
1033 | if (L_ECHO(tty)) | |
1034 | set_bit(REPRINT_CHAR(tty), | |
1035 | tty->process_char_map); | |
1036 | } | |
1037 | } | |
1038 | if (I_IXON(tty)) { | |
1039 | set_bit(START_CHAR(tty), tty->process_char_map); | |
1040 | set_bit(STOP_CHAR(tty), tty->process_char_map); | |
1041 | } | |
1042 | if (L_ISIG(tty)) { | |
1043 | set_bit(INTR_CHAR(tty), tty->process_char_map); | |
1044 | set_bit(QUIT_CHAR(tty), tty->process_char_map); | |
1045 | set_bit(SUSP_CHAR(tty), tty->process_char_map); | |
1046 | } | |
1047 | clear_bit(__DISABLED_CHAR, tty->process_char_map); | |
1048 | tty->raw = 0; | |
1049 | tty->real_raw = 0; | |
1050 | } else { | |
1051 | tty->raw = 1; | |
1052 | if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && | |
1053 | (I_IGNPAR(tty) || !I_INPCK(tty)) && | |
1054 | (tty->driver->flags & TTY_DRIVER_REAL_RAW)) | |
1055 | tty->real_raw = 1; | |
1056 | else | |
1057 | tty->real_raw = 0; | |
1058 | } | |
33f0f88f | 1059 | n_tty_set_room(tty); |
1da177e4 LT |
1060 | } |
1061 | ||
1062 | /** | |
1063 | * n_tty_close - close the ldisc for this tty | |
1064 | * @tty: device | |
1065 | * | |
1066 | * Called from the terminal layer when this line discipline is | |
1067 | * being shut down, either because of a close or becsuse of a | |
1068 | * discipline change. The function will not be called while other | |
1069 | * ldisc methods are in progress. | |
1070 | */ | |
1071 | ||
1072 | static void n_tty_close(struct tty_struct *tty) | |
1073 | { | |
1074 | n_tty_flush_buffer(tty); | |
1075 | if (tty->read_buf) { | |
1076 | free_buf(tty->read_buf); | |
1077 | tty->read_buf = NULL; | |
1078 | } | |
1079 | } | |
1080 | ||
1081 | /** | |
1082 | * n_tty_open - open an ldisc | |
1083 | * @tty: terminal to open | |
1084 | * | |
1085 | * Called when this line discipline is being attached to the | |
1086 | * terminal device. Can sleep. Called serialized so that no | |
1087 | * other events will occur in parallel. No further open will occur | |
1088 | * until a close. | |
1089 | */ | |
1090 | ||
1091 | static int n_tty_open(struct tty_struct *tty) | |
1092 | { | |
1093 | if (!tty) | |
1094 | return -EINVAL; | |
1095 | ||
1096 | /* This one is ugly. Currently a malloc failure here can panic */ | |
1097 | if (!tty->read_buf) { | |
1098 | tty->read_buf = alloc_buf(); | |
1099 | if (!tty->read_buf) | |
1100 | return -ENOMEM; | |
1101 | } | |
1102 | memset(tty->read_buf, 0, N_TTY_BUF_SIZE); | |
1103 | reset_buffer_flags(tty); | |
1104 | tty->column = 0; | |
1105 | n_tty_set_termios(tty, NULL); | |
1106 | tty->minimum_to_wake = 1; | |
1107 | tty->closing = 0; | |
1108 | return 0; | |
1109 | } | |
1110 | ||
1111 | static inline int input_available_p(struct tty_struct *tty, int amt) | |
1112 | { | |
1113 | if (tty->icanon) { | |
1114 | if (tty->canon_data) | |
1115 | return 1; | |
1116 | } else if (tty->read_cnt >= (amt ? amt : 1)) | |
1117 | return 1; | |
1118 | ||
1119 | return 0; | |
1120 | } | |
1121 | ||
1122 | /** | |
1123 | * copy_from_read_buf - copy read data directly | |
1124 | * @tty: terminal device | |
1125 | * @b: user data | |
1126 | * @nr: size of data | |
1127 | * | |
1128 | * Helper function to speed up read_chan. It is only called when | |
1129 | * ICANON is off; it copies characters straight from the tty queue to | |
1130 | * user space directly. It can be profitably called twice; once to | |
1131 | * drain the space from the tail pointer to the (physical) end of the | |
1132 | * buffer, and once to drain the space from the (physical) beginning of | |
1133 | * the buffer to head pointer. | |
1134 | * | |
70522e12 | 1135 | * Called under the tty->atomic_read_lock sem and with TTY_DONT_FLIP set |
1da177e4 LT |
1136 | * |
1137 | */ | |
1138 | ||
33f0f88f | 1139 | static int copy_from_read_buf(struct tty_struct *tty, |
1da177e4 LT |
1140 | unsigned char __user **b, |
1141 | size_t *nr) | |
1142 | ||
1143 | { | |
1144 | int retval; | |
1145 | size_t n; | |
1146 | unsigned long flags; | |
1147 | ||
1148 | retval = 0; | |
1149 | spin_lock_irqsave(&tty->read_lock, flags); | |
1150 | n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail); | |
1151 | n = min(*nr, n); | |
1152 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1153 | if (n) { | |
1154 | mb(); | |
1155 | retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n); | |
1156 | n -= retval; | |
1157 | spin_lock_irqsave(&tty->read_lock, flags); | |
1158 | tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1); | |
1159 | tty->read_cnt -= n; | |
1160 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1161 | *b += n; | |
1162 | *nr -= n; | |
1163 | } | |
1164 | return retval; | |
1165 | } | |
1166 | ||
1167 | extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *); | |
1168 | ||
1169 | /** | |
1170 | * job_control - check job control | |
1171 | * @tty: tty | |
1172 | * @file: file handle | |
1173 | * | |
1174 | * Perform job control management checks on this file/tty descriptor | |
1175 | * and if appropriate send any needed signals and return a negative | |
1176 | * error code if action should be taken. | |
1177 | */ | |
1178 | ||
1179 | static int job_control(struct tty_struct *tty, struct file *file) | |
1180 | { | |
1181 | /* Job control check -- must be done at start and after | |
1182 | every sleep (POSIX.1 7.1.1.4). */ | |
1183 | /* NOTE: not yet done after every sleep pending a thorough | |
1184 | check of the logic of this change. -- jlc */ | |
1185 | /* don't stop on /dev/console */ | |
1186 | if (file->f_op->write != redirected_tty_write && | |
1187 | current->signal->tty == tty) { | |
1188 | if (tty->pgrp <= 0) | |
1189 | printk("read_chan: tty->pgrp <= 0!\n"); | |
1190 | else if (process_group(current) != tty->pgrp) { | |
1191 | if (is_ignored(SIGTTIN) || | |
1192 | is_orphaned_pgrp(process_group(current))) | |
1193 | return -EIO; | |
1194 | kill_pg(process_group(current), SIGTTIN, 1); | |
1195 | return -ERESTARTSYS; | |
1196 | } | |
1197 | } | |
1198 | return 0; | |
1199 | } | |
1200 | ||
1201 | ||
1202 | /** | |
1203 | * read_chan - read function for tty | |
1204 | * @tty: tty device | |
1205 | * @file: file object | |
1206 | * @buf: userspace buffer pointer | |
1207 | * @nr: size of I/O | |
1208 | * | |
1209 | * Perform reads for the line discipline. We are guaranteed that the | |
1210 | * line discipline will not be closed under us but we may get multiple | |
1211 | * parallel readers and must handle this ourselves. We may also get | |
1212 | * a hangup. Always called in user context, may sleep. | |
1213 | * | |
1214 | * This code must be sure never to sleep through a hangup. | |
1215 | */ | |
1216 | ||
1217 | static ssize_t read_chan(struct tty_struct *tty, struct file *file, | |
1218 | unsigned char __user *buf, size_t nr) | |
1219 | { | |
1220 | unsigned char __user *b = buf; | |
1221 | DECLARE_WAITQUEUE(wait, current); | |
1222 | int c; | |
1223 | int minimum, time; | |
1224 | ssize_t retval = 0; | |
1225 | ssize_t size; | |
1226 | long timeout; | |
1227 | unsigned long flags; | |
1228 | ||
1229 | do_it_again: | |
1230 | ||
1231 | if (!tty->read_buf) { | |
1232 | printk("n_tty_read_chan: called with read_buf == NULL?!?\n"); | |
1233 | return -EIO; | |
1234 | } | |
1235 | ||
1236 | c = job_control(tty, file); | |
1237 | if(c < 0) | |
1238 | return c; | |
1239 | ||
1240 | minimum = time = 0; | |
1241 | timeout = MAX_SCHEDULE_TIMEOUT; | |
1242 | if (!tty->icanon) { | |
1243 | time = (HZ / 10) * TIME_CHAR(tty); | |
1244 | minimum = MIN_CHAR(tty); | |
1245 | if (minimum) { | |
1246 | if (time) | |
1247 | tty->minimum_to_wake = 1; | |
1248 | else if (!waitqueue_active(&tty->read_wait) || | |
1249 | (tty->minimum_to_wake > minimum)) | |
1250 | tty->minimum_to_wake = minimum; | |
1251 | } else { | |
1252 | timeout = 0; | |
1253 | if (time) { | |
1254 | timeout = time; | |
1255 | time = 0; | |
1256 | } | |
1257 | tty->minimum_to_wake = minimum = 1; | |
1258 | } | |
1259 | } | |
1260 | ||
1261 | /* | |
1262 | * Internal serialization of reads. | |
1263 | */ | |
1264 | if (file->f_flags & O_NONBLOCK) { | |
70522e12 | 1265 | if (!mutex_trylock(&tty->atomic_read_lock)) |
1da177e4 LT |
1266 | return -EAGAIN; |
1267 | } | |
1268 | else { | |
70522e12 | 1269 | if (mutex_lock_interruptible(&tty->atomic_read_lock)) |
1da177e4 LT |
1270 | return -ERESTARTSYS; |
1271 | } | |
1272 | ||
1273 | add_wait_queue(&tty->read_wait, &wait); | |
1274 | set_bit(TTY_DONT_FLIP, &tty->flags); | |
1275 | while (nr) { | |
1276 | /* First test for status change. */ | |
1277 | if (tty->packet && tty->link->ctrl_status) { | |
1278 | unsigned char cs; | |
1279 | if (b != buf) | |
1280 | break; | |
1281 | cs = tty->link->ctrl_status; | |
1282 | tty->link->ctrl_status = 0; | |
1283 | if (put_user(cs, b++)) { | |
1284 | retval = -EFAULT; | |
1285 | b--; | |
1286 | break; | |
1287 | } | |
1288 | nr--; | |
1289 | break; | |
1290 | } | |
1291 | /* This statement must be first before checking for input | |
1292 | so that any interrupt will set the state back to | |
1293 | TASK_RUNNING. */ | |
1294 | set_current_state(TASK_INTERRUPTIBLE); | |
1295 | ||
1296 | if (((minimum - (b - buf)) < tty->minimum_to_wake) && | |
1297 | ((minimum - (b - buf)) >= 1)) | |
1298 | tty->minimum_to_wake = (minimum - (b - buf)); | |
1299 | ||
1300 | if (!input_available_p(tty, 0)) { | |
1301 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { | |
1302 | retval = -EIO; | |
1303 | break; | |
1304 | } | |
1305 | if (tty_hung_up_p(file)) | |
1306 | break; | |
1307 | if (!timeout) | |
1308 | break; | |
1309 | if (file->f_flags & O_NONBLOCK) { | |
1310 | retval = -EAGAIN; | |
1311 | break; | |
1312 | } | |
1313 | if (signal_pending(current)) { | |
1314 | retval = -ERESTARTSYS; | |
1315 | break; | |
1316 | } | |
33f0f88f | 1317 | n_tty_set_room(tty); |
1da177e4 LT |
1318 | clear_bit(TTY_DONT_FLIP, &tty->flags); |
1319 | timeout = schedule_timeout(timeout); | |
1320 | set_bit(TTY_DONT_FLIP, &tty->flags); | |
1321 | continue; | |
1322 | } | |
1323 | __set_current_state(TASK_RUNNING); | |
1324 | ||
1325 | /* Deal with packet mode. */ | |
1326 | if (tty->packet && b == buf) { | |
1327 | if (put_user(TIOCPKT_DATA, b++)) { | |
1328 | retval = -EFAULT; | |
1329 | b--; | |
1330 | break; | |
1331 | } | |
1332 | nr--; | |
1333 | } | |
1334 | ||
1335 | if (tty->icanon) { | |
1336 | /* N.B. avoid overrun if nr == 0 */ | |
1337 | while (nr && tty->read_cnt) { | |
1338 | int eol; | |
1339 | ||
1340 | eol = test_and_clear_bit(tty->read_tail, | |
1341 | tty->read_flags); | |
1342 | c = tty->read_buf[tty->read_tail]; | |
1343 | spin_lock_irqsave(&tty->read_lock, flags); | |
1344 | tty->read_tail = ((tty->read_tail+1) & | |
1345 | (N_TTY_BUF_SIZE-1)); | |
1346 | tty->read_cnt--; | |
1347 | if (eol) { | |
1348 | /* this test should be redundant: | |
1349 | * we shouldn't be reading data if | |
1350 | * canon_data is 0 | |
1351 | */ | |
1352 | if (--tty->canon_data < 0) | |
1353 | tty->canon_data = 0; | |
1354 | } | |
1355 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1356 | ||
1357 | if (!eol || (c != __DISABLED_CHAR)) { | |
1358 | if (put_user(c, b++)) { | |
1359 | retval = -EFAULT; | |
1360 | b--; | |
1361 | break; | |
1362 | } | |
1363 | nr--; | |
1364 | } | |
1365 | if (eol) | |
1366 | break; | |
1367 | } | |
1368 | if (retval) | |
1369 | break; | |
1370 | } else { | |
1371 | int uncopied; | |
1372 | uncopied = copy_from_read_buf(tty, &b, &nr); | |
1373 | uncopied += copy_from_read_buf(tty, &b, &nr); | |
1374 | if (uncopied) { | |
1375 | retval = -EFAULT; | |
1376 | break; | |
1377 | } | |
1378 | } | |
1379 | ||
1380 | /* If there is enough space in the read buffer now, let the | |
1381 | * low-level driver know. We use n_tty_chars_in_buffer() to | |
1382 | * check the buffer, as it now knows about canonical mode. | |
1383 | * Otherwise, if the driver is throttled and the line is | |
1384 | * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, | |
1385 | * we won't get any more characters. | |
1386 | */ | |
289a1e99 PM |
1387 | if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) { |
1388 | n_tty_set_room(tty); | |
1da177e4 | 1389 | check_unthrottle(tty); |
289a1e99 | 1390 | } |
1da177e4 LT |
1391 | |
1392 | if (b - buf >= minimum) | |
1393 | break; | |
1394 | if (time) | |
1395 | timeout = time; | |
1396 | } | |
1397 | clear_bit(TTY_DONT_FLIP, &tty->flags); | |
70522e12 | 1398 | mutex_unlock(&tty->atomic_read_lock); |
1da177e4 LT |
1399 | remove_wait_queue(&tty->read_wait, &wait); |
1400 | ||
1401 | if (!waitqueue_active(&tty->read_wait)) | |
1402 | tty->minimum_to_wake = minimum; | |
1403 | ||
1404 | __set_current_state(TASK_RUNNING); | |
1405 | size = b - buf; | |
1406 | if (size) { | |
1407 | retval = size; | |
1408 | if (nr) | |
1409 | clear_bit(TTY_PUSH, &tty->flags); | |
1410 | } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) | |
1411 | goto do_it_again; | |
1412 | ||
33f0f88f AC |
1413 | n_tty_set_room(tty); |
1414 | ||
1da177e4 LT |
1415 | return retval; |
1416 | } | |
1417 | ||
1418 | /** | |
1419 | * write_chan - write function for tty | |
1420 | * @tty: tty device | |
1421 | * @file: file object | |
1422 | * @buf: userspace buffer pointer | |
1423 | * @nr: size of I/O | |
1424 | * | |
1425 | * Write function of the terminal device. This is serialized with | |
1426 | * respect to other write callers but not to termios changes, reads | |
1427 | * and other such events. We must be careful with N_TTY as the receive | |
1428 | * code will echo characters, thus calling driver write methods. | |
1429 | * | |
1430 | * This code must be sure never to sleep through a hangup. | |
1431 | */ | |
1432 | ||
1433 | static ssize_t write_chan(struct tty_struct * tty, struct file * file, | |
1434 | const unsigned char * buf, size_t nr) | |
1435 | { | |
1436 | const unsigned char *b = buf; | |
1437 | DECLARE_WAITQUEUE(wait, current); | |
1438 | int c; | |
1439 | ssize_t retval = 0; | |
1440 | ||
1441 | /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ | |
1442 | if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { | |
1443 | retval = tty_check_change(tty); | |
1444 | if (retval) | |
1445 | return retval; | |
1446 | } | |
1447 | ||
1448 | add_wait_queue(&tty->write_wait, &wait); | |
1449 | while (1) { | |
1450 | set_current_state(TASK_INTERRUPTIBLE); | |
1451 | if (signal_pending(current)) { | |
1452 | retval = -ERESTARTSYS; | |
1453 | break; | |
1454 | } | |
1455 | if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { | |
1456 | retval = -EIO; | |
1457 | break; | |
1458 | } | |
1459 | if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { | |
1460 | while (nr > 0) { | |
1461 | ssize_t num = opost_block(tty, b, nr); | |
1462 | if (num < 0) { | |
1463 | if (num == -EAGAIN) | |
1464 | break; | |
1465 | retval = num; | |
1466 | goto break_out; | |
1467 | } | |
1468 | b += num; | |
1469 | nr -= num; | |
1470 | if (nr == 0) | |
1471 | break; | |
1472 | c = *b; | |
1473 | if (opost(c, tty) < 0) | |
1474 | break; | |
1475 | b++; nr--; | |
1476 | } | |
1477 | if (tty->driver->flush_chars) | |
1478 | tty->driver->flush_chars(tty); | |
1479 | } else { | |
d6afe27b RZ |
1480 | while (nr > 0) { |
1481 | c = tty->driver->write(tty, b, nr); | |
1482 | if (c < 0) { | |
1483 | retval = c; | |
1484 | goto break_out; | |
1485 | } | |
1486 | if (!c) | |
1487 | break; | |
1488 | b += c; | |
1489 | nr -= c; | |
1da177e4 | 1490 | } |
1da177e4 LT |
1491 | } |
1492 | if (!nr) | |
1493 | break; | |
1494 | if (file->f_flags & O_NONBLOCK) { | |
1495 | retval = -EAGAIN; | |
1496 | break; | |
1497 | } | |
1498 | schedule(); | |
1499 | } | |
1500 | break_out: | |
1501 | __set_current_state(TASK_RUNNING); | |
1502 | remove_wait_queue(&tty->write_wait, &wait); | |
1503 | return (b - buf) ? b - buf : retval; | |
1504 | } | |
1505 | ||
1506 | /** | |
1507 | * normal_poll - poll method for N_TTY | |
1508 | * @tty: terminal device | |
1509 | * @file: file accessing it | |
1510 | * @wait: poll table | |
1511 | * | |
1512 | * Called when the line discipline is asked to poll() for data or | |
1513 | * for special events. This code is not serialized with respect to | |
1514 | * other events save open/close. | |
1515 | * | |
1516 | * This code must be sure never to sleep through a hangup. | |
1517 | * Called without the kernel lock held - fine | |
1518 | * | |
1519 | * FIXME: if someone changes the VMIN or discipline settings for the | |
1520 | * terminal while another process is in poll() the poll does not | |
1521 | * recompute the new limits. Possibly set_termios should issue | |
1522 | * a read wakeup to fix this bug. | |
1523 | */ | |
1524 | ||
1525 | static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait) | |
1526 | { | |
1527 | unsigned int mask = 0; | |
1528 | ||
1529 | poll_wait(file, &tty->read_wait, wait); | |
1530 | poll_wait(file, &tty->write_wait, wait); | |
1531 | if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) | |
1532 | mask |= POLLIN | POLLRDNORM; | |
1533 | if (tty->packet && tty->link->ctrl_status) | |
1534 | mask |= POLLPRI | POLLIN | POLLRDNORM; | |
1535 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
1536 | mask |= POLLHUP; | |
1537 | if (tty_hung_up_p(file)) | |
1538 | mask |= POLLHUP; | |
1539 | if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { | |
1540 | if (MIN_CHAR(tty) && !TIME_CHAR(tty)) | |
1541 | tty->minimum_to_wake = MIN_CHAR(tty); | |
1542 | else | |
1543 | tty->minimum_to_wake = 1; | |
1544 | } | |
1545 | if (tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS && | |
1546 | tty->driver->write_room(tty) > 0) | |
1547 | mask |= POLLOUT | POLLWRNORM; | |
1548 | return mask; | |
1549 | } | |
1550 | ||
1551 | struct tty_ldisc tty_ldisc_N_TTY = { | |
1552 | TTY_LDISC_MAGIC, /* magic */ | |
1553 | "n_tty", /* name */ | |
1554 | 0, /* num */ | |
1555 | 0, /* flags */ | |
1556 | n_tty_open, /* open */ | |
1557 | n_tty_close, /* close */ | |
1558 | n_tty_flush_buffer, /* flush_buffer */ | |
1559 | n_tty_chars_in_buffer, /* chars_in_buffer */ | |
1560 | read_chan, /* read */ | |
1561 | write_chan, /* write */ | |
1562 | n_tty_ioctl, /* ioctl */ | |
1563 | n_tty_set_termios, /* set_termios */ | |
1564 | normal_poll, /* poll */ | |
1565 | NULL, /* hangup */ | |
1566 | n_tty_receive_buf, /* receive_buf */ | |
1da177e4 LT |
1567 | n_tty_write_wakeup /* write_wakeup */ |
1568 | }; | |
1569 |