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 | { | |
65 | int prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL; | |
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 | ||
81 | static inline void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty) | |
82 | { | |
83 | if (tty->read_cnt < N_TTY_BUF_SIZE) { | |
84 | tty->read_buf[tty->read_head] = c; | |
85 | tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1); | |
86 | tty->read_cnt++; | |
87 | } | |
88 | } | |
89 | ||
90 | static inline void put_tty_queue(unsigned char c, struct tty_struct *tty) | |
91 | { | |
92 | unsigned long flags; | |
93 | /* | |
94 | * The problem of stomping on the buffers ends here. | |
95 | * Why didn't anyone see this one coming? --AJK | |
96 | */ | |
97 | spin_lock_irqsave(&tty->read_lock, flags); | |
98 | put_tty_queue_nolock(c, tty); | |
99 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
100 | } | |
101 | ||
102 | /** | |
103 | * check_unthrottle - allow new receive data | |
104 | * @tty; tty device | |
105 | * | |
106 | * Check whether to call the driver.unthrottle function. | |
107 | * We test the TTY_THROTTLED bit first so that it always | |
108 | * indicates the current state. The decision about whether | |
109 | * it is worth allowing more input has been taken by the caller. | |
110 | * Can sleep, may be called under the atomic_read semaphore but | |
111 | * this is not guaranteed. | |
112 | */ | |
113 | ||
114 | static void check_unthrottle(struct tty_struct * tty) | |
115 | { | |
116 | if (tty->count && | |
117 | test_and_clear_bit(TTY_THROTTLED, &tty->flags) && | |
118 | tty->driver->unthrottle) | |
119 | tty->driver->unthrottle(tty); | |
120 | } | |
121 | ||
122 | /** | |
123 | * reset_buffer_flags - reset buffer state | |
124 | * @tty: terminal to reset | |
125 | * | |
126 | * Reset the read buffer counters, clear the flags, | |
127 | * and make sure the driver is unthrottled. Called | |
128 | * from n_tty_open() and n_tty_flush_buffer(). | |
129 | */ | |
130 | static void reset_buffer_flags(struct tty_struct *tty) | |
131 | { | |
132 | unsigned long flags; | |
133 | ||
134 | spin_lock_irqsave(&tty->read_lock, flags); | |
135 | tty->read_head = tty->read_tail = tty->read_cnt = 0; | |
136 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
137 | tty->canon_head = tty->canon_data = tty->erasing = 0; | |
138 | memset(&tty->read_flags, 0, sizeof tty->read_flags); | |
139 | check_unthrottle(tty); | |
140 | } | |
141 | ||
142 | /** | |
143 | * n_tty_flush_buffer - clean input queue | |
144 | * @tty: terminal device | |
145 | * | |
146 | * Flush the input buffer. Called when the line discipline is | |
147 | * being closed, when the tty layer wants the buffer flushed (eg | |
148 | * at hangup) or when the N_TTY line discipline internally has to | |
149 | * clean the pending queue (for example some signals). | |
150 | * | |
151 | * FIXME: tty->ctrl_status is not spinlocked and relies on | |
152 | * lock_kernel() still. | |
153 | */ | |
154 | ||
155 | static void n_tty_flush_buffer(struct tty_struct * tty) | |
156 | { | |
157 | /* clear everything and unthrottle the driver */ | |
158 | reset_buffer_flags(tty); | |
159 | ||
160 | if (!tty->link) | |
161 | return; | |
162 | ||
163 | if (tty->link->packet) { | |
164 | tty->ctrl_status |= TIOCPKT_FLUSHREAD; | |
165 | wake_up_interruptible(&tty->link->read_wait); | |
166 | } | |
167 | } | |
168 | ||
169 | /** | |
170 | * n_tty_chars_in_buffer - report available bytes | |
171 | * @tty: tty device | |
172 | * | |
173 | * Report the number of characters buffered to be delivered to user | |
174 | * at this instant in time. | |
175 | */ | |
176 | ||
177 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) | |
178 | { | |
179 | unsigned long flags; | |
180 | ssize_t n = 0; | |
181 | ||
182 | spin_lock_irqsave(&tty->read_lock, flags); | |
183 | if (!tty->icanon) { | |
184 | n = tty->read_cnt; | |
185 | } else if (tty->canon_data) { | |
186 | n = (tty->canon_head > tty->read_tail) ? | |
187 | tty->canon_head - tty->read_tail : | |
188 | tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail); | |
189 | } | |
190 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
191 | return n; | |
192 | } | |
193 | ||
194 | /** | |
195 | * is_utf8_continuation - utf8 multibyte check | |
196 | * @c: byte to check | |
197 | * | |
198 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
199 | * character. We use this to correctly compute the on screen size | |
200 | * of the character when printing | |
201 | */ | |
202 | ||
203 | static inline int is_utf8_continuation(unsigned char c) | |
204 | { | |
205 | return (c & 0xc0) == 0x80; | |
206 | } | |
207 | ||
208 | /** | |
209 | * is_continuation - multibyte check | |
210 | * @c: byte to check | |
211 | * | |
212 | * Returns true if the utf8 character 'c' is a multibyte continuation | |
213 | * character and the terminal is in unicode mode. | |
214 | */ | |
215 | ||
216 | static inline int is_continuation(unsigned char c, struct tty_struct *tty) | |
217 | { | |
218 | return I_IUTF8(tty) && is_utf8_continuation(c); | |
219 | } | |
220 | ||
221 | /** | |
222 | * opost - output post processor | |
223 | * @c: character (or partial unicode symbol) | |
224 | * @tty: terminal device | |
225 | * | |
226 | * Perform OPOST processing. Returns -1 when the output device is | |
227 | * full and the character must be retried. Note that Linux currently | |
228 | * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't | |
229 | * relevant in the world today. If you ever need them, add them here. | |
230 | * | |
231 | * Called from both the receive and transmit sides and can be called | |
232 | * re-entrantly. Relies on lock_kernel() still. | |
233 | */ | |
234 | ||
235 | static int opost(unsigned char c, struct tty_struct *tty) | |
236 | { | |
237 | int space, spaces; | |
238 | ||
239 | space = tty->driver->write_room(tty); | |
240 | if (!space) | |
241 | return -1; | |
242 | ||
243 | if (O_OPOST(tty)) { | |
244 | switch (c) { | |
245 | case '\n': | |
246 | if (O_ONLRET(tty)) | |
247 | tty->column = 0; | |
248 | if (O_ONLCR(tty)) { | |
249 | if (space < 2) | |
250 | return -1; | |
251 | tty->driver->put_char(tty, '\r'); | |
252 | tty->column = 0; | |
253 | } | |
254 | tty->canon_column = tty->column; | |
255 | break; | |
256 | case '\r': | |
257 | if (O_ONOCR(tty) && tty->column == 0) | |
258 | return 0; | |
259 | if (O_OCRNL(tty)) { | |
260 | c = '\n'; | |
261 | if (O_ONLRET(tty)) | |
262 | tty->canon_column = tty->column = 0; | |
263 | break; | |
264 | } | |
265 | tty->canon_column = tty->column = 0; | |
266 | break; | |
267 | case '\t': | |
268 | spaces = 8 - (tty->column & 7); | |
269 | if (O_TABDLY(tty) == XTABS) { | |
270 | if (space < spaces) | |
271 | return -1; | |
272 | tty->column += spaces; | |
273 | tty->driver->write(tty, " ", spaces); | |
274 | return 0; | |
275 | } | |
276 | tty->column += spaces; | |
277 | break; | |
278 | case '\b': | |
279 | if (tty->column > 0) | |
280 | tty->column--; | |
281 | break; | |
282 | default: | |
283 | if (O_OLCUC(tty)) | |
284 | c = toupper(c); | |
285 | if (!iscntrl(c) && !is_continuation(c, tty)) | |
286 | tty->column++; | |
287 | break; | |
288 | } | |
289 | } | |
290 | tty->driver->put_char(tty, c); | |
291 | return 0; | |
292 | } | |
293 | ||
294 | /** | |
295 | * opost_block - block postprocess | |
296 | * @tty: terminal device | |
297 | * @inbuf: user buffer | |
298 | * @nr: number of bytes | |
299 | * | |
300 | * This path is used to speed up block console writes, among other | |
301 | * things when processing blocks of output data. It handles only | |
302 | * the simple cases normally found and helps to generate blocks of | |
303 | * symbols for the console driver and thus improve performance. | |
304 | * | |
305 | * Called from write_chan under the tty layer write lock. | |
306 | */ | |
307 | ||
308 | static ssize_t opost_block(struct tty_struct * tty, | |
309 | const unsigned char * buf, unsigned int nr) | |
310 | { | |
311 | int space; | |
312 | int i; | |
313 | const unsigned char *cp; | |
314 | ||
315 | space = tty->driver->write_room(tty); | |
316 | if (!space) | |
317 | return 0; | |
318 | if (nr > space) | |
319 | nr = space; | |
320 | ||
321 | for (i = 0, cp = buf; i < nr; i++, cp++) { | |
322 | switch (*cp) { | |
323 | case '\n': | |
324 | if (O_ONLRET(tty)) | |
325 | tty->column = 0; | |
326 | if (O_ONLCR(tty)) | |
327 | goto break_out; | |
328 | tty->canon_column = tty->column; | |
329 | break; | |
330 | case '\r': | |
331 | if (O_ONOCR(tty) && tty->column == 0) | |
332 | goto break_out; | |
333 | if (O_OCRNL(tty)) | |
334 | goto break_out; | |
335 | tty->canon_column = tty->column = 0; | |
336 | break; | |
337 | case '\t': | |
338 | goto break_out; | |
339 | case '\b': | |
340 | if (tty->column > 0) | |
341 | tty->column--; | |
342 | break; | |
343 | default: | |
344 | if (O_OLCUC(tty)) | |
345 | goto break_out; | |
346 | if (!iscntrl(*cp)) | |
347 | tty->column++; | |
348 | break; | |
349 | } | |
350 | } | |
351 | break_out: | |
352 | if (tty->driver->flush_chars) | |
353 | tty->driver->flush_chars(tty); | |
354 | i = tty->driver->write(tty, buf, i); | |
355 | return i; | |
356 | } | |
357 | ||
358 | ||
359 | /** | |
360 | * put_char - write character to driver | |
361 | * @c: character (or part of unicode symbol) | |
362 | * @tty: terminal device | |
363 | * | |
364 | * Queue a byte to the driver layer for output | |
365 | */ | |
366 | ||
367 | static inline void put_char(unsigned char c, struct tty_struct *tty) | |
368 | { | |
369 | tty->driver->put_char(tty, c); | |
370 | } | |
371 | ||
372 | /** | |
373 | * echo_char - echo characters | |
374 | * @c: unicode byte to echo | |
375 | * @tty: terminal device | |
376 | * | |
377 | * Echo user input back onto the screen. This must be called only when | |
378 | * L_ECHO(tty) is true. Called from the driver receive_buf path. | |
379 | */ | |
380 | ||
381 | static void echo_char(unsigned char c, struct tty_struct *tty) | |
382 | { | |
383 | if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') { | |
384 | put_char('^', tty); | |
385 | put_char(c ^ 0100, tty); | |
386 | tty->column += 2; | |
387 | } else | |
388 | opost(c, tty); | |
389 | } | |
390 | ||
391 | static inline void finish_erasing(struct tty_struct *tty) | |
392 | { | |
393 | if (tty->erasing) { | |
394 | put_char('/', tty); | |
395 | tty->column++; | |
396 | tty->erasing = 0; | |
397 | } | |
398 | } | |
399 | ||
400 | /** | |
401 | * eraser - handle erase function | |
402 | * @c: character input | |
403 | * @tty: terminal device | |
404 | * | |
405 | * Perform erase and neccessary output when an erase character is | |
406 | * present in the stream from the driver layer. Handles the complexities | |
407 | * of UTF-8 multibyte symbols. | |
408 | */ | |
409 | ||
410 | static void eraser(unsigned char c, struct tty_struct *tty) | |
411 | { | |
412 | enum { ERASE, WERASE, KILL } kill_type; | |
413 | int head, seen_alnums, cnt; | |
414 | unsigned long flags; | |
415 | ||
416 | if (tty->read_head == tty->canon_head) { | |
417 | /* opost('\a', tty); */ /* what do you think? */ | |
418 | return; | |
419 | } | |
420 | if (c == ERASE_CHAR(tty)) | |
421 | kill_type = ERASE; | |
422 | else if (c == WERASE_CHAR(tty)) | |
423 | kill_type = WERASE; | |
424 | else { | |
425 | if (!L_ECHO(tty)) { | |
426 | spin_lock_irqsave(&tty->read_lock, flags); | |
427 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & | |
428 | (N_TTY_BUF_SIZE - 1)); | |
429 | tty->read_head = tty->canon_head; | |
430 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
431 | return; | |
432 | } | |
433 | if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { | |
434 | spin_lock_irqsave(&tty->read_lock, flags); | |
435 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & | |
436 | (N_TTY_BUF_SIZE - 1)); | |
437 | tty->read_head = tty->canon_head; | |
438 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
439 | finish_erasing(tty); | |
440 | echo_char(KILL_CHAR(tty), tty); | |
441 | /* Add a newline if ECHOK is on and ECHOKE is off. */ | |
442 | if (L_ECHOK(tty)) | |
443 | opost('\n', tty); | |
444 | return; | |
445 | } | |
446 | kill_type = KILL; | |
447 | } | |
448 | ||
449 | seen_alnums = 0; | |
450 | while (tty->read_head != tty->canon_head) { | |
451 | head = tty->read_head; | |
452 | ||
453 | /* erase a single possibly multibyte character */ | |
454 | do { | |
455 | head = (head - 1) & (N_TTY_BUF_SIZE-1); | |
456 | c = tty->read_buf[head]; | |
457 | } while (is_continuation(c, tty) && head != tty->canon_head); | |
458 | ||
459 | /* do not partially erase */ | |
460 | if (is_continuation(c, tty)) | |
461 | break; | |
462 | ||
463 | if (kill_type == WERASE) { | |
464 | /* Equivalent to BSD's ALTWERASE. */ | |
465 | if (isalnum(c) || c == '_') | |
466 | seen_alnums++; | |
467 | else if (seen_alnums) | |
468 | break; | |
469 | } | |
470 | cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1); | |
471 | spin_lock_irqsave(&tty->read_lock, flags); | |
472 | tty->read_head = head; | |
473 | tty->read_cnt -= cnt; | |
474 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
475 | if (L_ECHO(tty)) { | |
476 | if (L_ECHOPRT(tty)) { | |
477 | if (!tty->erasing) { | |
478 | put_char('\\', tty); | |
479 | tty->column++; | |
480 | tty->erasing = 1; | |
481 | } | |
482 | /* if cnt > 1, output a multi-byte character */ | |
483 | echo_char(c, tty); | |
484 | while (--cnt > 0) { | |
485 | head = (head+1) & (N_TTY_BUF_SIZE-1); | |
486 | put_char(tty->read_buf[head], tty); | |
487 | } | |
488 | } else if (kill_type == ERASE && !L_ECHOE(tty)) { | |
489 | echo_char(ERASE_CHAR(tty), tty); | |
490 | } else if (c == '\t') { | |
491 | unsigned int col = tty->canon_column; | |
492 | unsigned long tail = tty->canon_head; | |
493 | ||
494 | /* Find the column of the last char. */ | |
495 | while (tail != tty->read_head) { | |
496 | c = tty->read_buf[tail]; | |
497 | if (c == '\t') | |
498 | col = (col | 7) + 1; | |
499 | else if (iscntrl(c)) { | |
500 | if (L_ECHOCTL(tty)) | |
501 | col += 2; | |
502 | } else if (!is_continuation(c, tty)) | |
503 | col++; | |
504 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); | |
505 | } | |
506 | ||
507 | /* should never happen */ | |
508 | if (tty->column > 0x80000000) | |
509 | tty->column = 0; | |
510 | ||
511 | /* Now backup to that column. */ | |
512 | while (tty->column > col) { | |
513 | /* Can't use opost here. */ | |
514 | put_char('\b', tty); | |
515 | if (tty->column > 0) | |
516 | tty->column--; | |
517 | } | |
518 | } else { | |
519 | if (iscntrl(c) && L_ECHOCTL(tty)) { | |
520 | put_char('\b', tty); | |
521 | put_char(' ', tty); | |
522 | put_char('\b', tty); | |
523 | if (tty->column > 0) | |
524 | tty->column--; | |
525 | } | |
526 | if (!iscntrl(c) || L_ECHOCTL(tty)) { | |
527 | put_char('\b', tty); | |
528 | put_char(' ', tty); | |
529 | put_char('\b', tty); | |
530 | if (tty->column > 0) | |
531 | tty->column--; | |
532 | } | |
533 | } | |
534 | } | |
535 | if (kill_type == ERASE) | |
536 | break; | |
537 | } | |
538 | if (tty->read_head == tty->canon_head) | |
539 | finish_erasing(tty); | |
540 | } | |
541 | ||
542 | /** | |
543 | * isig - handle the ISIG optio | |
544 | * @sig: signal | |
545 | * @tty: terminal | |
546 | * @flush: force flush | |
547 | * | |
548 | * Called when a signal is being sent due to terminal input. This | |
549 | * may caus terminal flushing to take place according to the termios | |
550 | * settings and character used. Called from the driver receive_buf | |
551 | * path so serialized. | |
552 | */ | |
553 | ||
554 | static inline void isig(int sig, struct tty_struct *tty, int flush) | |
555 | { | |
556 | if (tty->pgrp > 0) | |
557 | kill_pg(tty->pgrp, sig, 1); | |
558 | if (flush || !L_NOFLSH(tty)) { | |
559 | n_tty_flush_buffer(tty); | |
560 | if (tty->driver->flush_buffer) | |
561 | tty->driver->flush_buffer(tty); | |
562 | } | |
563 | } | |
564 | ||
565 | /** | |
566 | * n_tty_receive_break - handle break | |
567 | * @tty: terminal | |
568 | * | |
569 | * An RS232 break event has been hit in the incoming bitstream. This | |
570 | * can cause a variety of events depending upon the termios settings. | |
571 | * | |
572 | * Called from the receive_buf path so single threaded. | |
573 | */ | |
574 | ||
575 | static inline void n_tty_receive_break(struct tty_struct *tty) | |
576 | { | |
577 | if (I_IGNBRK(tty)) | |
578 | return; | |
579 | if (I_BRKINT(tty)) { | |
580 | isig(SIGINT, tty, 1); | |
581 | return; | |
582 | } | |
583 | if (I_PARMRK(tty)) { | |
584 | put_tty_queue('\377', tty); | |
585 | put_tty_queue('\0', tty); | |
586 | } | |
587 | put_tty_queue('\0', tty); | |
588 | wake_up_interruptible(&tty->read_wait); | |
589 | } | |
590 | ||
591 | /** | |
592 | * n_tty_receive_overrun - handle overrun reporting | |
593 | * @tty: terminal | |
594 | * | |
595 | * Data arrived faster than we could process it. While the tty | |
596 | * driver has flagged this the bits that were missed are gone | |
597 | * forever. | |
598 | * | |
599 | * Called from the receive_buf path so single threaded. Does not | |
600 | * need locking as num_overrun and overrun_time are function | |
601 | * private. | |
602 | */ | |
603 | ||
604 | static inline void n_tty_receive_overrun(struct tty_struct *tty) | |
605 | { | |
606 | char buf[64]; | |
607 | ||
608 | tty->num_overrun++; | |
609 | if (time_before(tty->overrun_time, jiffies - HZ) || | |
610 | time_after(tty->overrun_time, jiffies)) { | |
611 | printk(KERN_WARNING "%s: %d input overrun(s)\n", | |
612 | tty_name(tty, buf), | |
613 | tty->num_overrun); | |
614 | tty->overrun_time = jiffies; | |
615 | tty->num_overrun = 0; | |
616 | } | |
617 | } | |
618 | ||
619 | /** | |
620 | * n_tty_receive_parity_error - error notifier | |
621 | * @tty: terminal device | |
622 | * @c: character | |
623 | * | |
624 | * Process a parity error and queue the right data to indicate | |
625 | * the error case if neccessary. Locking as per n_tty_receive_buf. | |
626 | */ | |
627 | static inline void n_tty_receive_parity_error(struct tty_struct *tty, | |
628 | unsigned char c) | |
629 | { | |
630 | if (I_IGNPAR(tty)) { | |
631 | return; | |
632 | } | |
633 | if (I_PARMRK(tty)) { | |
634 | put_tty_queue('\377', tty); | |
635 | put_tty_queue('\0', tty); | |
636 | put_tty_queue(c, tty); | |
637 | } else if (I_INPCK(tty)) | |
638 | put_tty_queue('\0', tty); | |
639 | else | |
640 | put_tty_queue(c, tty); | |
641 | wake_up_interruptible(&tty->read_wait); | |
642 | } | |
643 | ||
644 | /** | |
645 | * n_tty_receive_char - perform processing | |
646 | * @tty: terminal device | |
647 | * @c: character | |
648 | * | |
649 | * Process an individual character of input received from the driver. | |
650 | * This is serialized with respect to itself by the rules for the | |
651 | * driver above. | |
652 | */ | |
653 | ||
654 | static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) | |
655 | { | |
656 | unsigned long flags; | |
657 | ||
658 | if (tty->raw) { | |
659 | put_tty_queue(c, tty); | |
660 | return; | |
661 | } | |
662 | ||
663 | if (tty->stopped && !tty->flow_stopped && | |
664 | I_IXON(tty) && I_IXANY(tty)) { | |
665 | start_tty(tty); | |
666 | return; | |
667 | } | |
668 | ||
669 | if (I_ISTRIP(tty)) | |
670 | c &= 0x7f; | |
671 | if (I_IUCLC(tty) && L_IEXTEN(tty)) | |
672 | c=tolower(c); | |
673 | ||
674 | if (tty->closing) { | |
675 | if (I_IXON(tty)) { | |
676 | if (c == START_CHAR(tty)) | |
677 | start_tty(tty); | |
678 | else if (c == STOP_CHAR(tty)) | |
679 | stop_tty(tty); | |
680 | } | |
681 | return; | |
682 | } | |
683 | ||
684 | /* | |
685 | * If the previous character was LNEXT, or we know that this | |
686 | * character is not one of the characters that we'll have to | |
687 | * handle specially, do shortcut processing to speed things | |
688 | * up. | |
689 | */ | |
690 | if (!test_bit(c, tty->process_char_map) || tty->lnext) { | |
691 | finish_erasing(tty); | |
692 | tty->lnext = 0; | |
693 | if (L_ECHO(tty)) { | |
694 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { | |
695 | put_char('\a', tty); /* beep if no space */ | |
696 | return; | |
697 | } | |
698 | /* Record the column of first canon char. */ | |
699 | if (tty->canon_head == tty->read_head) | |
700 | tty->canon_column = tty->column; | |
701 | echo_char(c, tty); | |
702 | } | |
703 | if (I_PARMRK(tty) && c == (unsigned char) '\377') | |
704 | put_tty_queue(c, tty); | |
705 | put_tty_queue(c, tty); | |
706 | return; | |
707 | } | |
708 | ||
709 | if (c == '\r') { | |
710 | if (I_IGNCR(tty)) | |
711 | return; | |
712 | if (I_ICRNL(tty)) | |
713 | c = '\n'; | |
714 | } else if (c == '\n' && I_INLCR(tty)) | |
715 | c = '\r'; | |
716 | if (I_IXON(tty)) { | |
717 | if (c == START_CHAR(tty)) { | |
718 | start_tty(tty); | |
719 | return; | |
720 | } | |
721 | if (c == STOP_CHAR(tty)) { | |
722 | stop_tty(tty); | |
723 | return; | |
724 | } | |
725 | } | |
726 | if (L_ISIG(tty)) { | |
727 | int signal; | |
728 | signal = SIGINT; | |
729 | if (c == INTR_CHAR(tty)) | |
730 | goto send_signal; | |
731 | signal = SIGQUIT; | |
732 | if (c == QUIT_CHAR(tty)) | |
733 | goto send_signal; | |
734 | signal = SIGTSTP; | |
735 | if (c == SUSP_CHAR(tty)) { | |
736 | send_signal: | |
737 | isig(signal, tty, 0); | |
738 | return; | |
739 | } | |
740 | } | |
741 | if (tty->icanon) { | |
742 | if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || | |
743 | (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { | |
744 | eraser(c, tty); | |
745 | return; | |
746 | } | |
747 | if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { | |
748 | tty->lnext = 1; | |
749 | if (L_ECHO(tty)) { | |
750 | finish_erasing(tty); | |
751 | if (L_ECHOCTL(tty)) { | |
752 | put_char('^', tty); | |
753 | put_char('\b', tty); | |
754 | } | |
755 | } | |
756 | return; | |
757 | } | |
758 | if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && | |
759 | L_IEXTEN(tty)) { | |
760 | unsigned long tail = tty->canon_head; | |
761 | ||
762 | finish_erasing(tty); | |
763 | echo_char(c, tty); | |
764 | opost('\n', tty); | |
765 | while (tail != tty->read_head) { | |
766 | echo_char(tty->read_buf[tail], tty); | |
767 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); | |
768 | } | |
769 | return; | |
770 | } | |
771 | if (c == '\n') { | |
772 | if (L_ECHO(tty) || L_ECHONL(tty)) { | |
773 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { | |
774 | put_char('\a', tty); | |
775 | return; | |
776 | } | |
777 | opost('\n', tty); | |
778 | } | |
779 | goto handle_newline; | |
780 | } | |
781 | if (c == EOF_CHAR(tty)) { | |
782 | if (tty->canon_head != tty->read_head) | |
783 | set_bit(TTY_PUSH, &tty->flags); | |
784 | c = __DISABLED_CHAR; | |
785 | goto handle_newline; | |
786 | } | |
787 | if ((c == EOL_CHAR(tty)) || | |
788 | (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { | |
789 | /* | |
790 | * XXX are EOL_CHAR and EOL2_CHAR echoed?!? | |
791 | */ | |
792 | if (L_ECHO(tty)) { | |
793 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { | |
794 | put_char('\a', tty); | |
795 | return; | |
796 | } | |
797 | /* Record the column of first canon char. */ | |
798 | if (tty->canon_head == tty->read_head) | |
799 | tty->canon_column = tty->column; | |
800 | echo_char(c, tty); | |
801 | } | |
802 | /* | |
803 | * XXX does PARMRK doubling happen for | |
804 | * EOL_CHAR and EOL2_CHAR? | |
805 | */ | |
806 | if (I_PARMRK(tty) && c == (unsigned char) '\377') | |
807 | put_tty_queue(c, tty); | |
808 | ||
809 | handle_newline: | |
810 | spin_lock_irqsave(&tty->read_lock, flags); | |
811 | set_bit(tty->read_head, tty->read_flags); | |
812 | put_tty_queue_nolock(c, tty); | |
813 | tty->canon_head = tty->read_head; | |
814 | tty->canon_data++; | |
815 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
816 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
817 | if (waitqueue_active(&tty->read_wait)) | |
818 | wake_up_interruptible(&tty->read_wait); | |
819 | return; | |
820 | } | |
821 | } | |
822 | ||
823 | finish_erasing(tty); | |
824 | if (L_ECHO(tty)) { | |
825 | if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { | |
826 | put_char('\a', tty); /* beep if no space */ | |
827 | return; | |
828 | } | |
829 | if (c == '\n') | |
830 | opost('\n', tty); | |
831 | else { | |
832 | /* Record the column of first canon char. */ | |
833 | if (tty->canon_head == tty->read_head) | |
834 | tty->canon_column = tty->column; | |
835 | echo_char(c, tty); | |
836 | } | |
837 | } | |
838 | ||
839 | if (I_PARMRK(tty) && c == (unsigned char) '\377') | |
840 | put_tty_queue(c, tty); | |
841 | ||
842 | put_tty_queue(c, tty); | |
843 | } | |
844 | ||
845 | /** | |
846 | * n_tty_receive_room - receive space | |
847 | * @tty: terminal | |
848 | * | |
849 | * Called by the driver to find out how much data it is | |
850 | * permitted to feed to the line discipline without any being lost | |
851 | * and thus to manage flow control. Not serialized. Answers for the | |
852 | * "instant". | |
853 | */ | |
854 | ||
855 | static int n_tty_receive_room(struct tty_struct *tty) | |
856 | { | |
857 | int left = N_TTY_BUF_SIZE - tty->read_cnt - 1; | |
858 | ||
859 | /* | |
860 | * If we are doing input canonicalization, and there are no | |
861 | * pending newlines, let characters through without limit, so | |
862 | * that erase characters will be handled. Other excess | |
863 | * characters will be beeped. | |
864 | */ | |
865 | if (tty->icanon && !tty->canon_data) | |
866 | return N_TTY_BUF_SIZE; | |
867 | ||
868 | if (left > 0) | |
869 | return left; | |
870 | return 0; | |
871 | } | |
872 | ||
873 | /** | |
874 | * n_tty_write_wakeup - asynchronous I/O notifier | |
875 | * @tty: tty device | |
876 | * | |
877 | * Required for the ptys, serial driver etc. since processes | |
878 | * that attach themselves to the master and rely on ASYNC | |
879 | * IO must be woken up | |
880 | */ | |
881 | ||
882 | static void n_tty_write_wakeup(struct tty_struct *tty) | |
883 | { | |
884 | if (tty->fasync) | |
885 | { | |
886 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); | |
887 | kill_fasync(&tty->fasync, SIGIO, POLL_OUT); | |
888 | } | |
889 | return; | |
890 | } | |
891 | ||
892 | /** | |
893 | * n_tty_receive_buf - data receive | |
894 | * @tty: terminal device | |
895 | * @cp: buffer | |
896 | * @fp: flag buffer | |
897 | * @count: characters | |
898 | * | |
899 | * Called by the terminal driver when a block of characters has | |
900 | * been received. This function must be called from soft contexts | |
901 | * not from interrupt context. The driver is responsible for making | |
902 | * calls one at a time and in order (or using flush_to_ldisc) | |
903 | */ | |
904 | ||
905 | static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, | |
906 | char *fp, int count) | |
907 | { | |
908 | const unsigned char *p; | |
909 | char *f, flags = TTY_NORMAL; | |
910 | int i; | |
911 | char buf[64]; | |
912 | unsigned long cpuflags; | |
913 | ||
914 | if (!tty->read_buf) | |
915 | return; | |
916 | ||
917 | if (tty->real_raw) { | |
918 | spin_lock_irqsave(&tty->read_lock, cpuflags); | |
919 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, | |
920 | N_TTY_BUF_SIZE - tty->read_head); | |
921 | i = min(count, i); | |
922 | memcpy(tty->read_buf + tty->read_head, cp, i); | |
923 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); | |
924 | tty->read_cnt += i; | |
925 | cp += i; | |
926 | count -= i; | |
927 | ||
928 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, | |
929 | N_TTY_BUF_SIZE - tty->read_head); | |
930 | i = min(count, i); | |
931 | memcpy(tty->read_buf + tty->read_head, cp, i); | |
932 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); | |
933 | tty->read_cnt += i; | |
934 | spin_unlock_irqrestore(&tty->read_lock, cpuflags); | |
935 | } else { | |
936 | for (i=count, p = cp, f = fp; i; i--, p++) { | |
937 | if (f) | |
938 | flags = *f++; | |
939 | switch (flags) { | |
940 | case TTY_NORMAL: | |
941 | n_tty_receive_char(tty, *p); | |
942 | break; | |
943 | case TTY_BREAK: | |
944 | n_tty_receive_break(tty); | |
945 | break; | |
946 | case TTY_PARITY: | |
947 | case TTY_FRAME: | |
948 | n_tty_receive_parity_error(tty, *p); | |
949 | break; | |
950 | case TTY_OVERRUN: | |
951 | n_tty_receive_overrun(tty); | |
952 | break; | |
953 | default: | |
954 | printk("%s: unknown flag %d\n", | |
955 | tty_name(tty, buf), flags); | |
956 | break; | |
957 | } | |
958 | } | |
959 | if (tty->driver->flush_chars) | |
960 | tty->driver->flush_chars(tty); | |
961 | } | |
962 | ||
963 | if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) { | |
964 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); | |
965 | if (waitqueue_active(&tty->read_wait)) | |
966 | wake_up_interruptible(&tty->read_wait); | |
967 | } | |
968 | ||
969 | /* | |
970 | * Check the remaining room for the input canonicalization | |
971 | * mode. We don't want to throttle the driver if we're in | |
972 | * canonical mode and don't have a newline yet! | |
973 | */ | |
974 | if (n_tty_receive_room(tty) < TTY_THRESHOLD_THROTTLE) { | |
975 | /* check TTY_THROTTLED first so it indicates our state */ | |
976 | if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) && | |
977 | tty->driver->throttle) | |
978 | tty->driver->throttle(tty); | |
979 | } | |
980 | } | |
981 | ||
982 | int is_ignored(int sig) | |
983 | { | |
984 | return (sigismember(¤t->blocked, sig) || | |
985 | current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); | |
986 | } | |
987 | ||
988 | /** | |
989 | * n_tty_set_termios - termios data changed | |
990 | * @tty: terminal | |
991 | * @old: previous data | |
992 | * | |
993 | * Called by the tty layer when the user changes termios flags so | |
994 | * that the line discipline can plan ahead. This function cannot sleep | |
995 | * and is protected from re-entry by the tty layer. The user is | |
996 | * guaranteed that this function will not be re-entered or in progress | |
997 | * when the ldisc is closed. | |
998 | */ | |
999 | ||
1000 | static void n_tty_set_termios(struct tty_struct *tty, struct termios * old) | |
1001 | { | |
1002 | if (!tty) | |
1003 | return; | |
1004 | ||
1005 | tty->icanon = (L_ICANON(tty) != 0); | |
1006 | if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { | |
1007 | tty->raw = 1; | |
1008 | tty->real_raw = 1; | |
1009 | return; | |
1010 | } | |
1011 | if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || | |
1012 | I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || | |
1013 | I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || | |
1014 | I_PARMRK(tty)) { | |
1015 | memset(tty->process_char_map, 0, 256/8); | |
1016 | ||
1017 | if (I_IGNCR(tty) || I_ICRNL(tty)) | |
1018 | set_bit('\r', tty->process_char_map); | |
1019 | if (I_INLCR(tty)) | |
1020 | set_bit('\n', tty->process_char_map); | |
1021 | ||
1022 | if (L_ICANON(tty)) { | |
1023 | set_bit(ERASE_CHAR(tty), tty->process_char_map); | |
1024 | set_bit(KILL_CHAR(tty), tty->process_char_map); | |
1025 | set_bit(EOF_CHAR(tty), tty->process_char_map); | |
1026 | set_bit('\n', tty->process_char_map); | |
1027 | set_bit(EOL_CHAR(tty), tty->process_char_map); | |
1028 | if (L_IEXTEN(tty)) { | |
1029 | set_bit(WERASE_CHAR(tty), | |
1030 | tty->process_char_map); | |
1031 | set_bit(LNEXT_CHAR(tty), | |
1032 | tty->process_char_map); | |
1033 | set_bit(EOL2_CHAR(tty), | |
1034 | tty->process_char_map); | |
1035 | if (L_ECHO(tty)) | |
1036 | set_bit(REPRINT_CHAR(tty), | |
1037 | tty->process_char_map); | |
1038 | } | |
1039 | } | |
1040 | if (I_IXON(tty)) { | |
1041 | set_bit(START_CHAR(tty), tty->process_char_map); | |
1042 | set_bit(STOP_CHAR(tty), tty->process_char_map); | |
1043 | } | |
1044 | if (L_ISIG(tty)) { | |
1045 | set_bit(INTR_CHAR(tty), tty->process_char_map); | |
1046 | set_bit(QUIT_CHAR(tty), tty->process_char_map); | |
1047 | set_bit(SUSP_CHAR(tty), tty->process_char_map); | |
1048 | } | |
1049 | clear_bit(__DISABLED_CHAR, tty->process_char_map); | |
1050 | tty->raw = 0; | |
1051 | tty->real_raw = 0; | |
1052 | } else { | |
1053 | tty->raw = 1; | |
1054 | if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && | |
1055 | (I_IGNPAR(tty) || !I_INPCK(tty)) && | |
1056 | (tty->driver->flags & TTY_DRIVER_REAL_RAW)) | |
1057 | tty->real_raw = 1; | |
1058 | else | |
1059 | tty->real_raw = 0; | |
1060 | } | |
1061 | } | |
1062 | ||
1063 | /** | |
1064 | * n_tty_close - close the ldisc for this tty | |
1065 | * @tty: device | |
1066 | * | |
1067 | * Called from the terminal layer when this line discipline is | |
1068 | * being shut down, either because of a close or becsuse of a | |
1069 | * discipline change. The function will not be called while other | |
1070 | * ldisc methods are in progress. | |
1071 | */ | |
1072 | ||
1073 | static void n_tty_close(struct tty_struct *tty) | |
1074 | { | |
1075 | n_tty_flush_buffer(tty); | |
1076 | if (tty->read_buf) { | |
1077 | free_buf(tty->read_buf); | |
1078 | tty->read_buf = NULL; | |
1079 | } | |
1080 | } | |
1081 | ||
1082 | /** | |
1083 | * n_tty_open - open an ldisc | |
1084 | * @tty: terminal to open | |
1085 | * | |
1086 | * Called when this line discipline is being attached to the | |
1087 | * terminal device. Can sleep. Called serialized so that no | |
1088 | * other events will occur in parallel. No further open will occur | |
1089 | * until a close. | |
1090 | */ | |
1091 | ||
1092 | static int n_tty_open(struct tty_struct *tty) | |
1093 | { | |
1094 | if (!tty) | |
1095 | return -EINVAL; | |
1096 | ||
1097 | /* This one is ugly. Currently a malloc failure here can panic */ | |
1098 | if (!tty->read_buf) { | |
1099 | tty->read_buf = alloc_buf(); | |
1100 | if (!tty->read_buf) | |
1101 | return -ENOMEM; | |
1102 | } | |
1103 | memset(tty->read_buf, 0, N_TTY_BUF_SIZE); | |
1104 | reset_buffer_flags(tty); | |
1105 | tty->column = 0; | |
1106 | n_tty_set_termios(tty, NULL); | |
1107 | tty->minimum_to_wake = 1; | |
1108 | tty->closing = 0; | |
1109 | return 0; | |
1110 | } | |
1111 | ||
1112 | static inline int input_available_p(struct tty_struct *tty, int amt) | |
1113 | { | |
1114 | if (tty->icanon) { | |
1115 | if (tty->canon_data) | |
1116 | return 1; | |
1117 | } else if (tty->read_cnt >= (amt ? amt : 1)) | |
1118 | return 1; | |
1119 | ||
1120 | return 0; | |
1121 | } | |
1122 | ||
1123 | /** | |
1124 | * copy_from_read_buf - copy read data directly | |
1125 | * @tty: terminal device | |
1126 | * @b: user data | |
1127 | * @nr: size of data | |
1128 | * | |
1129 | * Helper function to speed up read_chan. It is only called when | |
1130 | * ICANON is off; it copies characters straight from the tty queue to | |
1131 | * user space directly. It can be profitably called twice; once to | |
1132 | * drain the space from the tail pointer to the (physical) end of the | |
1133 | * buffer, and once to drain the space from the (physical) beginning of | |
1134 | * the buffer to head pointer. | |
1135 | * | |
1136 | * Called under the tty->atomic_read sem and with TTY_DONT_FLIP set | |
1137 | * | |
1138 | */ | |
1139 | ||
1140 | static inline int copy_from_read_buf(struct tty_struct *tty, | |
1141 | unsigned char __user **b, | |
1142 | size_t *nr) | |
1143 | ||
1144 | { | |
1145 | int retval; | |
1146 | size_t n; | |
1147 | unsigned long flags; | |
1148 | ||
1149 | retval = 0; | |
1150 | spin_lock_irqsave(&tty->read_lock, flags); | |
1151 | n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail); | |
1152 | n = min(*nr, n); | |
1153 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1154 | if (n) { | |
1155 | mb(); | |
1156 | retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n); | |
1157 | n -= retval; | |
1158 | spin_lock_irqsave(&tty->read_lock, flags); | |
1159 | tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1); | |
1160 | tty->read_cnt -= n; | |
1161 | spin_unlock_irqrestore(&tty->read_lock, flags); | |
1162 | *b += n; | |
1163 | *nr -= n; | |
1164 | } | |
1165 | return retval; | |
1166 | } | |
1167 | ||
1168 | extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *); | |
1169 | ||
1170 | /** | |
1171 | * job_control - check job control | |
1172 | * @tty: tty | |
1173 | * @file: file handle | |
1174 | * | |
1175 | * Perform job control management checks on this file/tty descriptor | |
1176 | * and if appropriate send any needed signals and return a negative | |
1177 | * error code if action should be taken. | |
1178 | */ | |
1179 | ||
1180 | static int job_control(struct tty_struct *tty, struct file *file) | |
1181 | { | |
1182 | /* Job control check -- must be done at start and after | |
1183 | every sleep (POSIX.1 7.1.1.4). */ | |
1184 | /* NOTE: not yet done after every sleep pending a thorough | |
1185 | check of the logic of this change. -- jlc */ | |
1186 | /* don't stop on /dev/console */ | |
1187 | if (file->f_op->write != redirected_tty_write && | |
1188 | current->signal->tty == tty) { | |
1189 | if (tty->pgrp <= 0) | |
1190 | printk("read_chan: tty->pgrp <= 0!\n"); | |
1191 | else if (process_group(current) != tty->pgrp) { | |
1192 | if (is_ignored(SIGTTIN) || | |
1193 | is_orphaned_pgrp(process_group(current))) | |
1194 | return -EIO; | |
1195 | kill_pg(process_group(current), SIGTTIN, 1); | |
1196 | return -ERESTARTSYS; | |
1197 | } | |
1198 | } | |
1199 | return 0; | |
1200 | } | |
1201 | ||
1202 | ||
1203 | /** | |
1204 | * read_chan - read function for tty | |
1205 | * @tty: tty device | |
1206 | * @file: file object | |
1207 | * @buf: userspace buffer pointer | |
1208 | * @nr: size of I/O | |
1209 | * | |
1210 | * Perform reads for the line discipline. We are guaranteed that the | |
1211 | * line discipline will not be closed under us but we may get multiple | |
1212 | * parallel readers and must handle this ourselves. We may also get | |
1213 | * a hangup. Always called in user context, may sleep. | |
1214 | * | |
1215 | * This code must be sure never to sleep through a hangup. | |
1216 | */ | |
1217 | ||
1218 | static ssize_t read_chan(struct tty_struct *tty, struct file *file, | |
1219 | unsigned char __user *buf, size_t nr) | |
1220 | { | |
1221 | unsigned char __user *b = buf; | |
1222 | DECLARE_WAITQUEUE(wait, current); | |
1223 | int c; | |
1224 | int minimum, time; | |
1225 | ssize_t retval = 0; | |
1226 | ssize_t size; | |
1227 | long timeout; | |
1228 | unsigned long flags; | |
1229 | ||
1230 | do_it_again: | |
1231 | ||
1232 | if (!tty->read_buf) { | |
1233 | printk("n_tty_read_chan: called with read_buf == NULL?!?\n"); | |
1234 | return -EIO; | |
1235 | } | |
1236 | ||
1237 | c = job_control(tty, file); | |
1238 | if(c < 0) | |
1239 | return c; | |
1240 | ||
1241 | minimum = time = 0; | |
1242 | timeout = MAX_SCHEDULE_TIMEOUT; | |
1243 | if (!tty->icanon) { | |
1244 | time = (HZ / 10) * TIME_CHAR(tty); | |
1245 | minimum = MIN_CHAR(tty); | |
1246 | if (minimum) { | |
1247 | if (time) | |
1248 | tty->minimum_to_wake = 1; | |
1249 | else if (!waitqueue_active(&tty->read_wait) || | |
1250 | (tty->minimum_to_wake > minimum)) | |
1251 | tty->minimum_to_wake = minimum; | |
1252 | } else { | |
1253 | timeout = 0; | |
1254 | if (time) { | |
1255 | timeout = time; | |
1256 | time = 0; | |
1257 | } | |
1258 | tty->minimum_to_wake = minimum = 1; | |
1259 | } | |
1260 | } | |
1261 | ||
1262 | /* | |
1263 | * Internal serialization of reads. | |
1264 | */ | |
1265 | if (file->f_flags & O_NONBLOCK) { | |
1266 | if (down_trylock(&tty->atomic_read)) | |
1267 | return -EAGAIN; | |
1268 | } | |
1269 | else { | |
1270 | if (down_interruptible(&tty->atomic_read)) | |
1271 | return -ERESTARTSYS; | |
1272 | } | |
1273 | ||
1274 | add_wait_queue(&tty->read_wait, &wait); | |
1275 | set_bit(TTY_DONT_FLIP, &tty->flags); | |
1276 | while (nr) { | |
1277 | /* First test for status change. */ | |
1278 | if (tty->packet && tty->link->ctrl_status) { | |
1279 | unsigned char cs; | |
1280 | if (b != buf) | |
1281 | break; | |
1282 | cs = tty->link->ctrl_status; | |
1283 | tty->link->ctrl_status = 0; | |
1284 | if (put_user(cs, b++)) { | |
1285 | retval = -EFAULT; | |
1286 | b--; | |
1287 | break; | |
1288 | } | |
1289 | nr--; | |
1290 | break; | |
1291 | } | |
1292 | /* This statement must be first before checking for input | |
1293 | so that any interrupt will set the state back to | |
1294 | TASK_RUNNING. */ | |
1295 | set_current_state(TASK_INTERRUPTIBLE); | |
1296 | ||
1297 | if (((minimum - (b - buf)) < tty->minimum_to_wake) && | |
1298 | ((minimum - (b - buf)) >= 1)) | |
1299 | tty->minimum_to_wake = (minimum - (b - buf)); | |
1300 | ||
1301 | if (!input_available_p(tty, 0)) { | |
1302 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { | |
1303 | retval = -EIO; | |
1304 | break; | |
1305 | } | |
1306 | if (tty_hung_up_p(file)) | |
1307 | break; | |
1308 | if (!timeout) | |
1309 | break; | |
1310 | if (file->f_flags & O_NONBLOCK) { | |
1311 | retval = -EAGAIN; | |
1312 | break; | |
1313 | } | |
1314 | if (signal_pending(current)) { | |
1315 | retval = -ERESTARTSYS; | |
1316 | break; | |
1317 | } | |
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 | */ | |
1387 | if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) | |
1388 | check_unthrottle(tty); | |
1389 | ||
1390 | if (b - buf >= minimum) | |
1391 | break; | |
1392 | if (time) | |
1393 | timeout = time; | |
1394 | } | |
1395 | clear_bit(TTY_DONT_FLIP, &tty->flags); | |
1396 | up(&tty->atomic_read); | |
1397 | remove_wait_queue(&tty->read_wait, &wait); | |
1398 | ||
1399 | if (!waitqueue_active(&tty->read_wait)) | |
1400 | tty->minimum_to_wake = minimum; | |
1401 | ||
1402 | __set_current_state(TASK_RUNNING); | |
1403 | size = b - buf; | |
1404 | if (size) { | |
1405 | retval = size; | |
1406 | if (nr) | |
1407 | clear_bit(TTY_PUSH, &tty->flags); | |
1408 | } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) | |
1409 | goto do_it_again; | |
1410 | ||
1411 | return retval; | |
1412 | } | |
1413 | ||
1414 | /** | |
1415 | * write_chan - write function for tty | |
1416 | * @tty: tty device | |
1417 | * @file: file object | |
1418 | * @buf: userspace buffer pointer | |
1419 | * @nr: size of I/O | |
1420 | * | |
1421 | * Write function of the terminal device. This is serialized with | |
1422 | * respect to other write callers but not to termios changes, reads | |
1423 | * and other such events. We must be careful with N_TTY as the receive | |
1424 | * code will echo characters, thus calling driver write methods. | |
1425 | * | |
1426 | * This code must be sure never to sleep through a hangup. | |
1427 | */ | |
1428 | ||
1429 | static ssize_t write_chan(struct tty_struct * tty, struct file * file, | |
1430 | const unsigned char * buf, size_t nr) | |
1431 | { | |
1432 | const unsigned char *b = buf; | |
1433 | DECLARE_WAITQUEUE(wait, current); | |
1434 | int c; | |
1435 | ssize_t retval = 0; | |
1436 | ||
1437 | /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ | |
1438 | if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { | |
1439 | retval = tty_check_change(tty); | |
1440 | if (retval) | |
1441 | return retval; | |
1442 | } | |
1443 | ||
1444 | add_wait_queue(&tty->write_wait, &wait); | |
1445 | while (1) { | |
1446 | set_current_state(TASK_INTERRUPTIBLE); | |
1447 | if (signal_pending(current)) { | |
1448 | retval = -ERESTARTSYS; | |
1449 | break; | |
1450 | } | |
1451 | if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { | |
1452 | retval = -EIO; | |
1453 | break; | |
1454 | } | |
1455 | if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { | |
1456 | while (nr > 0) { | |
1457 | ssize_t num = opost_block(tty, b, nr); | |
1458 | if (num < 0) { | |
1459 | if (num == -EAGAIN) | |
1460 | break; | |
1461 | retval = num; | |
1462 | goto break_out; | |
1463 | } | |
1464 | b += num; | |
1465 | nr -= num; | |
1466 | if (nr == 0) | |
1467 | break; | |
1468 | c = *b; | |
1469 | if (opost(c, tty) < 0) | |
1470 | break; | |
1471 | b++; nr--; | |
1472 | } | |
1473 | if (tty->driver->flush_chars) | |
1474 | tty->driver->flush_chars(tty); | |
1475 | } else { | |
1476 | c = tty->driver->write(tty, b, nr); | |
1477 | if (c < 0) { | |
1478 | retval = c; | |
1479 | goto break_out; | |
1480 | } | |
1481 | b += c; | |
1482 | nr -= c; | |
1483 | } | |
1484 | if (!nr) | |
1485 | break; | |
1486 | if (file->f_flags & O_NONBLOCK) { | |
1487 | retval = -EAGAIN; | |
1488 | break; | |
1489 | } | |
1490 | schedule(); | |
1491 | } | |
1492 | break_out: | |
1493 | __set_current_state(TASK_RUNNING); | |
1494 | remove_wait_queue(&tty->write_wait, &wait); | |
1495 | return (b - buf) ? b - buf : retval; | |
1496 | } | |
1497 | ||
1498 | /** | |
1499 | * normal_poll - poll method for N_TTY | |
1500 | * @tty: terminal device | |
1501 | * @file: file accessing it | |
1502 | * @wait: poll table | |
1503 | * | |
1504 | * Called when the line discipline is asked to poll() for data or | |
1505 | * for special events. This code is not serialized with respect to | |
1506 | * other events save open/close. | |
1507 | * | |
1508 | * This code must be sure never to sleep through a hangup. | |
1509 | * Called without the kernel lock held - fine | |
1510 | * | |
1511 | * FIXME: if someone changes the VMIN or discipline settings for the | |
1512 | * terminal while another process is in poll() the poll does not | |
1513 | * recompute the new limits. Possibly set_termios should issue | |
1514 | * a read wakeup to fix this bug. | |
1515 | */ | |
1516 | ||
1517 | static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait) | |
1518 | { | |
1519 | unsigned int mask = 0; | |
1520 | ||
1521 | poll_wait(file, &tty->read_wait, wait); | |
1522 | poll_wait(file, &tty->write_wait, wait); | |
1523 | if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) | |
1524 | mask |= POLLIN | POLLRDNORM; | |
1525 | if (tty->packet && tty->link->ctrl_status) | |
1526 | mask |= POLLPRI | POLLIN | POLLRDNORM; | |
1527 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
1528 | mask |= POLLHUP; | |
1529 | if (tty_hung_up_p(file)) | |
1530 | mask |= POLLHUP; | |
1531 | if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { | |
1532 | if (MIN_CHAR(tty) && !TIME_CHAR(tty)) | |
1533 | tty->minimum_to_wake = MIN_CHAR(tty); | |
1534 | else | |
1535 | tty->minimum_to_wake = 1; | |
1536 | } | |
1537 | if (tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS && | |
1538 | tty->driver->write_room(tty) > 0) | |
1539 | mask |= POLLOUT | POLLWRNORM; | |
1540 | return mask; | |
1541 | } | |
1542 | ||
1543 | struct tty_ldisc tty_ldisc_N_TTY = { | |
1544 | TTY_LDISC_MAGIC, /* magic */ | |
1545 | "n_tty", /* name */ | |
1546 | 0, /* num */ | |
1547 | 0, /* flags */ | |
1548 | n_tty_open, /* open */ | |
1549 | n_tty_close, /* close */ | |
1550 | n_tty_flush_buffer, /* flush_buffer */ | |
1551 | n_tty_chars_in_buffer, /* chars_in_buffer */ | |
1552 | read_chan, /* read */ | |
1553 | write_chan, /* write */ | |
1554 | n_tty_ioctl, /* ioctl */ | |
1555 | n_tty_set_termios, /* set_termios */ | |
1556 | normal_poll, /* poll */ | |
1557 | NULL, /* hangup */ | |
1558 | n_tty_receive_buf, /* receive_buf */ | |
1559 | n_tty_receive_room, /* receive_room */ | |
1560 | n_tty_write_wakeup /* write_wakeup */ | |
1561 | }; | |
1562 |