Root/
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 n_tty_write 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 | #include <linux/audit.h> |
49 | #include <linux/file.h> |
50 | #include <linux/uaccess.h> |
51 | #include <linux/module.h> |
52 | |
53 | #include <asm/system.h> |
54 | |
55 | /* number of characters left in xmit buffer before select has we have room */ |
56 | #define WAKEUP_CHARS 256 |
57 | |
58 | /* |
59 | * This defines the low- and high-watermarks for throttling and |
60 | * unthrottling the TTY driver. These watermarks are used for |
61 | * controlling the space in the read buffer. |
62 | */ |
63 | #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ |
64 | #define TTY_THRESHOLD_UNTHROTTLE 128 |
65 | |
66 | /* |
67 | * Special byte codes used in the echo buffer to represent operations |
68 | * or special handling of characters. Bytes in the echo buffer that |
69 | * are not part of such special blocks are treated as normal character |
70 | * codes. |
71 | */ |
72 | #define ECHO_OP_START 0xff |
73 | #define ECHO_OP_MOVE_BACK_COL 0x80 |
74 | #define ECHO_OP_SET_CANON_COL 0x81 |
75 | #define ECHO_OP_ERASE_TAB 0x82 |
76 | |
77 | static inline int tty_put_user(struct tty_struct *tty, unsigned char x, |
78 | unsigned char __user *ptr) |
79 | { |
80 | tty_audit_add_data(tty, &x, 1); |
81 | return put_user(x, ptr); |
82 | } |
83 | |
84 | /** |
85 | * n_tty_set__room - receive space |
86 | * @tty: terminal |
87 | * |
88 | * Called by the driver to find out how much data it is |
89 | * permitted to feed to the line discipline without any being lost |
90 | * and thus to manage flow control. Not serialized. Answers for the |
91 | * "instant". |
92 | */ |
93 | |
94 | static void n_tty_set_room(struct tty_struct *tty) |
95 | { |
96 | /* tty->read_cnt is not read locked ? */ |
97 | int left = N_TTY_BUF_SIZE - tty->read_cnt - 1; |
98 | |
99 | /* |
100 | * If we are doing input canonicalization, and there are no |
101 | * pending newlines, let characters through without limit, so |
102 | * that erase characters will be handled. Other excess |
103 | * characters will be beeped. |
104 | */ |
105 | if (left <= 0) |
106 | left = tty->icanon && !tty->canon_data; |
107 | tty->receive_room = left; |
108 | } |
109 | |
110 | static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty) |
111 | { |
112 | if (tty->read_cnt < N_TTY_BUF_SIZE) { |
113 | tty->read_buf[tty->read_head] = c; |
114 | tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1); |
115 | tty->read_cnt++; |
116 | } |
117 | } |
118 | |
119 | /** |
120 | * put_tty_queue - add character to tty |
121 | * @c: character |
122 | * @tty: tty device |
123 | * |
124 | * Add a character to the tty read_buf queue. This is done under the |
125 | * read_lock to serialize character addition and also to protect us |
126 | * against parallel reads or flushes |
127 | */ |
128 | |
129 | static void put_tty_queue(unsigned char c, struct tty_struct *tty) |
130 | { |
131 | unsigned long flags; |
132 | /* |
133 | * The problem of stomping on the buffers ends here. |
134 | * Why didn't anyone see this one coming? --AJK |
135 | */ |
136 | spin_lock_irqsave(&tty->read_lock, flags); |
137 | put_tty_queue_nolock(c, tty); |
138 | spin_unlock_irqrestore(&tty->read_lock, flags); |
139 | } |
140 | |
141 | /** |
142 | * check_unthrottle - allow new receive data |
143 | * @tty; tty device |
144 | * |
145 | * Check whether to call the driver unthrottle functions |
146 | * |
147 | * Can sleep, may be called under the atomic_read_lock mutex but |
148 | * this is not guaranteed. |
149 | */ |
150 | static void check_unthrottle(struct tty_struct *tty) |
151 | { |
152 | if (tty->count) |
153 | tty_unthrottle(tty); |
154 | } |
155 | |
156 | /** |
157 | * reset_buffer_flags - reset buffer state |
158 | * @tty: terminal to reset |
159 | * |
160 | * Reset the read buffer counters, clear the flags, |
161 | * and make sure the driver is unthrottled. Called |
162 | * from n_tty_open() and n_tty_flush_buffer(). |
163 | * |
164 | * Locking: tty_read_lock for read fields. |
165 | */ |
166 | |
167 | static void reset_buffer_flags(struct tty_struct *tty) |
168 | { |
169 | unsigned long flags; |
170 | |
171 | spin_lock_irqsave(&tty->read_lock, flags); |
172 | tty->read_head = tty->read_tail = tty->read_cnt = 0; |
173 | spin_unlock_irqrestore(&tty->read_lock, flags); |
174 | |
175 | mutex_lock(&tty->echo_lock); |
176 | tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0; |
177 | mutex_unlock(&tty->echo_lock); |
178 | |
179 | tty->canon_head = tty->canon_data = tty->erasing = 0; |
180 | memset(&tty->read_flags, 0, sizeof tty->read_flags); |
181 | n_tty_set_room(tty); |
182 | check_unthrottle(tty); |
183 | } |
184 | |
185 | /** |
186 | * n_tty_flush_buffer - clean input queue |
187 | * @tty: terminal device |
188 | * |
189 | * Flush the input buffer. Called when the line discipline is |
190 | * being closed, when the tty layer wants the buffer flushed (eg |
191 | * at hangup) or when the N_TTY line discipline internally has to |
192 | * clean the pending queue (for example some signals). |
193 | * |
194 | * Locking: ctrl_lock, read_lock. |
195 | */ |
196 | |
197 | static void n_tty_flush_buffer(struct tty_struct *tty) |
198 | { |
199 | unsigned long flags; |
200 | /* clear everything and unthrottle the driver */ |
201 | reset_buffer_flags(tty); |
202 | |
203 | if (!tty->link) |
204 | return; |
205 | |
206 | spin_lock_irqsave(&tty->ctrl_lock, flags); |
207 | if (tty->link->packet) { |
208 | tty->ctrl_status |= TIOCPKT_FLUSHREAD; |
209 | wake_up_interruptible(&tty->link->read_wait); |
210 | } |
211 | spin_unlock_irqrestore(&tty->ctrl_lock, flags); |
212 | } |
213 | |
214 | /** |
215 | * n_tty_chars_in_buffer - report available bytes |
216 | * @tty: tty device |
217 | * |
218 | * Report the number of characters buffered to be delivered to user |
219 | * at this instant in time. |
220 | * |
221 | * Locking: read_lock |
222 | */ |
223 | |
224 | static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) |
225 | { |
226 | unsigned long flags; |
227 | ssize_t n = 0; |
228 | |
229 | spin_lock_irqsave(&tty->read_lock, flags); |
230 | if (!tty->icanon) { |
231 | n = tty->read_cnt; |
232 | } else if (tty->canon_data) { |
233 | n = (tty->canon_head > tty->read_tail) ? |
234 | tty->canon_head - tty->read_tail : |
235 | tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail); |
236 | } |
237 | spin_unlock_irqrestore(&tty->read_lock, flags); |
238 | return n; |
239 | } |
240 | |
241 | /** |
242 | * is_utf8_continuation - utf8 multibyte check |
243 | * @c: byte to check |
244 | * |
245 | * Returns true if the utf8 character 'c' is a multibyte continuation |
246 | * character. We use this to correctly compute the on screen size |
247 | * of the character when printing |
248 | */ |
249 | |
250 | static inline int is_utf8_continuation(unsigned char c) |
251 | { |
252 | return (c & 0xc0) == 0x80; |
253 | } |
254 | |
255 | /** |
256 | * is_continuation - multibyte check |
257 | * @c: byte to check |
258 | * |
259 | * Returns true if the utf8 character 'c' is a multibyte continuation |
260 | * character and the terminal is in unicode mode. |
261 | */ |
262 | |
263 | static inline int is_continuation(unsigned char c, struct tty_struct *tty) |
264 | { |
265 | return I_IUTF8(tty) && is_utf8_continuation(c); |
266 | } |
267 | |
268 | /** |
269 | * do_output_char - output one character |
270 | * @c: character (or partial unicode symbol) |
271 | * @tty: terminal device |
272 | * @space: space available in tty driver write buffer |
273 | * |
274 | * This is a helper function that handles one output character |
275 | * (including special characters like TAB, CR, LF, etc.), |
276 | * doing OPOST processing and putting the results in the |
277 | * tty driver's write buffer. |
278 | * |
279 | * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY |
280 | * and NLDLY. They simply aren't relevant in the world today. |
281 | * If you ever need them, add them here. |
282 | * |
283 | * Returns the number of bytes of buffer space used or -1 if |
284 | * no space left. |
285 | * |
286 | * Locking: should be called under the output_lock to protect |
287 | * the column state and space left in the buffer |
288 | */ |
289 | |
290 | static int do_output_char(unsigned char c, struct tty_struct *tty, int space) |
291 | { |
292 | int spaces; |
293 | |
294 | if (!space) |
295 | return -1; |
296 | |
297 | switch (c) { |
298 | case '\n': |
299 | if (O_ONLRET(tty)) |
300 | tty->column = 0; |
301 | if (O_ONLCR(tty)) { |
302 | if (space < 2) |
303 | return -1; |
304 | tty->canon_column = tty->column = 0; |
305 | tty->ops->write(tty, "\r\n", 2); |
306 | return 2; |
307 | } |
308 | tty->canon_column = tty->column; |
309 | break; |
310 | case '\r': |
311 | if (O_ONOCR(tty) && tty->column == 0) |
312 | return 0; |
313 | if (O_OCRNL(tty)) { |
314 | c = '\n'; |
315 | if (O_ONLRET(tty)) |
316 | tty->canon_column = tty->column = 0; |
317 | break; |
318 | } |
319 | tty->canon_column = tty->column = 0; |
320 | break; |
321 | case '\t': |
322 | spaces = 8 - (tty->column & 7); |
323 | if (O_TABDLY(tty) == XTABS) { |
324 | if (space < spaces) |
325 | return -1; |
326 | tty->column += spaces; |
327 | tty->ops->write(tty, " ", spaces); |
328 | return spaces; |
329 | } |
330 | tty->column += spaces; |
331 | break; |
332 | case '\b': |
333 | if (tty->column > 0) |
334 | tty->column--; |
335 | break; |
336 | default: |
337 | if (!iscntrl(c)) { |
338 | if (O_OLCUC(tty)) |
339 | c = toupper(c); |
340 | if (!is_continuation(c, tty)) |
341 | tty->column++; |
342 | } |
343 | break; |
344 | } |
345 | |
346 | tty_put_char(tty, c); |
347 | return 1; |
348 | } |
349 | |
350 | /** |
351 | * process_output - output post processor |
352 | * @c: character (or partial unicode symbol) |
353 | * @tty: terminal device |
354 | * |
355 | * Output one character with OPOST processing. |
356 | * Returns -1 when the output device is full and the character |
357 | * must be retried. |
358 | * |
359 | * Locking: output_lock to protect column state and space left |
360 | * (also, this is called from n_tty_write under the |
361 | * tty layer write lock) |
362 | */ |
363 | |
364 | static int process_output(unsigned char c, struct tty_struct *tty) |
365 | { |
366 | int space, retval; |
367 | |
368 | mutex_lock(&tty->output_lock); |
369 | |
370 | space = tty_write_room(tty); |
371 | retval = do_output_char(c, tty, space); |
372 | |
373 | mutex_unlock(&tty->output_lock); |
374 | if (retval < 0) |
375 | return -1; |
376 | else |
377 | return 0; |
378 | } |
379 | |
380 | /** |
381 | * process_output_block - block post processor |
382 | * @tty: terminal device |
383 | * @buf: character buffer |
384 | * @nr: number of bytes to output |
385 | * |
386 | * Output a block of characters with OPOST processing. |
387 | * Returns the number of characters output. |
388 | * |
389 | * This path is used to speed up block console writes, among other |
390 | * things when processing blocks of output data. It handles only |
391 | * the simple cases normally found and helps to generate blocks of |
392 | * symbols for the console driver and thus improve performance. |
393 | * |
394 | * Locking: output_lock to protect column state and space left |
395 | * (also, this is called from n_tty_write under the |
396 | * tty layer write lock) |
397 | */ |
398 | |
399 | static ssize_t process_output_block(struct tty_struct *tty, |
400 | const unsigned char *buf, unsigned int nr) |
401 | { |
402 | int space; |
403 | int i; |
404 | const unsigned char *cp; |
405 | |
406 | mutex_lock(&tty->output_lock); |
407 | |
408 | space = tty_write_room(tty); |
409 | if (!space) { |
410 | mutex_unlock(&tty->output_lock); |
411 | return 0; |
412 | } |
413 | if (nr > space) |
414 | nr = space; |
415 | |
416 | for (i = 0, cp = buf; i < nr; i++, cp++) { |
417 | unsigned char c = *cp; |
418 | |
419 | switch (c) { |
420 | case '\n': |
421 | if (O_ONLRET(tty)) |
422 | tty->column = 0; |
423 | if (O_ONLCR(tty)) |
424 | goto break_out; |
425 | tty->canon_column = tty->column; |
426 | break; |
427 | case '\r': |
428 | if (O_ONOCR(tty) && tty->column == 0) |
429 | goto break_out; |
430 | if (O_OCRNL(tty)) |
431 | goto break_out; |
432 | tty->canon_column = tty->column = 0; |
433 | break; |
434 | case '\t': |
435 | goto break_out; |
436 | case '\b': |
437 | if (tty->column > 0) |
438 | tty->column--; |
439 | break; |
440 | default: |
441 | if (!iscntrl(c)) { |
442 | if (O_OLCUC(tty)) |
443 | goto break_out; |
444 | if (!is_continuation(c, tty)) |
445 | tty->column++; |
446 | } |
447 | break; |
448 | } |
449 | } |
450 | break_out: |
451 | i = tty->ops->write(tty, buf, i); |
452 | |
453 | mutex_unlock(&tty->output_lock); |
454 | return i; |
455 | } |
456 | |
457 | /** |
458 | * process_echoes - write pending echo characters |
459 | * @tty: terminal device |
460 | * |
461 | * Write previously buffered echo (and other ldisc-generated) |
462 | * characters to the tty. |
463 | * |
464 | * Characters generated by the ldisc (including echoes) need to |
465 | * be buffered because the driver's write buffer can fill during |
466 | * heavy program output. Echoing straight to the driver will |
467 | * often fail under these conditions, causing lost characters and |
468 | * resulting mismatches of ldisc state information. |
469 | * |
470 | * Since the ldisc state must represent the characters actually sent |
471 | * to the driver at the time of the write, operations like certain |
472 | * changes in column state are also saved in the buffer and executed |
473 | * here. |
474 | * |
475 | * A circular fifo buffer is used so that the most recent characters |
476 | * are prioritized. Also, when control characters are echoed with a |
477 | * prefixed "^", the pair is treated atomically and thus not separated. |
478 | * |
479 | * Locking: output_lock to protect column state and space left, |
480 | * echo_lock to protect the echo buffer |
481 | */ |
482 | |
483 | static void process_echoes(struct tty_struct *tty) |
484 | { |
485 | int space, nr; |
486 | unsigned char c; |
487 | unsigned char *cp, *buf_end; |
488 | |
489 | if (!tty->echo_cnt) |
490 | return; |
491 | |
492 | mutex_lock(&tty->output_lock); |
493 | mutex_lock(&tty->echo_lock); |
494 | |
495 | space = tty_write_room(tty); |
496 | |
497 | buf_end = tty->echo_buf + N_TTY_BUF_SIZE; |
498 | cp = tty->echo_buf + tty->echo_pos; |
499 | nr = tty->echo_cnt; |
500 | while (nr > 0) { |
501 | c = *cp; |
502 | if (c == ECHO_OP_START) { |
503 | unsigned char op; |
504 | unsigned char *opp; |
505 | int no_space_left = 0; |
506 | |
507 | /* |
508 | * If the buffer byte is the start of a multi-byte |
509 | * operation, get the next byte, which is either the |
510 | * op code or a control character value. |
511 | */ |
512 | opp = cp + 1; |
513 | if (opp == buf_end) |
514 | opp -= N_TTY_BUF_SIZE; |
515 | op = *opp; |
516 | |
517 | switch (op) { |
518 | unsigned int num_chars, num_bs; |
519 | |
520 | case ECHO_OP_ERASE_TAB: |
521 | if (++opp == buf_end) |
522 | opp -= N_TTY_BUF_SIZE; |
523 | num_chars = *opp; |
524 | |
525 | /* |
526 | * Determine how many columns to go back |
527 | * in order to erase the tab. |
528 | * This depends on the number of columns |
529 | * used by other characters within the tab |
530 | * area. If this (modulo 8) count is from |
531 | * the start of input rather than from a |
532 | * previous tab, we offset by canon column. |
533 | * Otherwise, tab spacing is normal. |
534 | */ |
535 | if (!(num_chars & 0x80)) |
536 | num_chars += tty->canon_column; |
537 | num_bs = 8 - (num_chars & 7); |
538 | |
539 | if (num_bs > space) { |
540 | no_space_left = 1; |
541 | break; |
542 | } |
543 | space -= num_bs; |
544 | while (num_bs--) { |
545 | tty_put_char(tty, '\b'); |
546 | if (tty->column > 0) |
547 | tty->column--; |
548 | } |
549 | cp += 3; |
550 | nr -= 3; |
551 | break; |
552 | |
553 | case ECHO_OP_SET_CANON_COL: |
554 | tty->canon_column = tty->column; |
555 | cp += 2; |
556 | nr -= 2; |
557 | break; |
558 | |
559 | case ECHO_OP_MOVE_BACK_COL: |
560 | if (tty->column > 0) |
561 | tty->column--; |
562 | cp += 2; |
563 | nr -= 2; |
564 | break; |
565 | |
566 | case ECHO_OP_START: |
567 | /* This is an escaped echo op start code */ |
568 | if (!space) { |
569 | no_space_left = 1; |
570 | break; |
571 | } |
572 | tty_put_char(tty, ECHO_OP_START); |
573 | tty->column++; |
574 | space--; |
575 | cp += 2; |
576 | nr -= 2; |
577 | break; |
578 | |
579 | default: |
580 | /* |
581 | * If the op is not a special byte code, |
582 | * it is a ctrl char tagged to be echoed |
583 | * as "^X" (where X is the letter |
584 | * representing the control char). |
585 | * Note that we must ensure there is |
586 | * enough space for the whole ctrl pair. |
587 | * |
588 | */ |
589 | if (space < 2) { |
590 | no_space_left = 1; |
591 | break; |
592 | } |
593 | tty_put_char(tty, '^'); |
594 | tty_put_char(tty, op ^ 0100); |
595 | tty->column += 2; |
596 | space -= 2; |
597 | cp += 2; |
598 | nr -= 2; |
599 | } |
600 | |
601 | if (no_space_left) |
602 | break; |
603 | } else { |
604 | if (O_OPOST(tty) && |
605 | !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { |
606 | int retval = do_output_char(c, tty, space); |
607 | if (retval < 0) |
608 | break; |
609 | space -= retval; |
610 | } else { |
611 | if (!space) |
612 | break; |
613 | tty_put_char(tty, c); |
614 | space -= 1; |
615 | } |
616 | cp += 1; |
617 | nr -= 1; |
618 | } |
619 | |
620 | /* When end of circular buffer reached, wrap around */ |
621 | if (cp >= buf_end) |
622 | cp -= N_TTY_BUF_SIZE; |
623 | } |
624 | |
625 | if (nr == 0) { |
626 | tty->echo_pos = 0; |
627 | tty->echo_cnt = 0; |
628 | tty->echo_overrun = 0; |
629 | } else { |
630 | int num_processed = tty->echo_cnt - nr; |
631 | tty->echo_pos += num_processed; |
632 | tty->echo_pos &= N_TTY_BUF_SIZE - 1; |
633 | tty->echo_cnt = nr; |
634 | if (num_processed > 0) |
635 | tty->echo_overrun = 0; |
636 | } |
637 | |
638 | mutex_unlock(&tty->echo_lock); |
639 | mutex_unlock(&tty->output_lock); |
640 | |
641 | if (tty->ops->flush_chars) |
642 | tty->ops->flush_chars(tty); |
643 | } |
644 | |
645 | /** |
646 | * add_echo_byte - add a byte to the echo buffer |
647 | * @c: unicode byte to echo |
648 | * @tty: terminal device |
649 | * |
650 | * Add a character or operation byte to the echo buffer. |
651 | * |
652 | * Should be called under the echo lock to protect the echo buffer. |
653 | */ |
654 | |
655 | static void add_echo_byte(unsigned char c, struct tty_struct *tty) |
656 | { |
657 | int new_byte_pos; |
658 | |
659 | if (tty->echo_cnt == N_TTY_BUF_SIZE) { |
660 | /* Circular buffer is already at capacity */ |
661 | new_byte_pos = tty->echo_pos; |
662 | |
663 | /* |
664 | * Since the buffer start position needs to be advanced, |
665 | * be sure to step by a whole operation byte group. |
666 | */ |
667 | if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) { |
668 | if (tty->echo_buf[(tty->echo_pos + 1) & |
669 | (N_TTY_BUF_SIZE - 1)] == |
670 | ECHO_OP_ERASE_TAB) { |
671 | tty->echo_pos += 3; |
672 | tty->echo_cnt -= 2; |
673 | } else { |
674 | tty->echo_pos += 2; |
675 | tty->echo_cnt -= 1; |
676 | } |
677 | } else { |
678 | tty->echo_pos++; |
679 | } |
680 | tty->echo_pos &= N_TTY_BUF_SIZE - 1; |
681 | |
682 | tty->echo_overrun = 1; |
683 | } else { |
684 | new_byte_pos = tty->echo_pos + tty->echo_cnt; |
685 | new_byte_pos &= N_TTY_BUF_SIZE - 1; |
686 | tty->echo_cnt++; |
687 | } |
688 | |
689 | tty->echo_buf[new_byte_pos] = c; |
690 | } |
691 | |
692 | /** |
693 | * echo_move_back_col - add operation to move back a column |
694 | * @tty: terminal device |
695 | * |
696 | * Add an operation to the echo buffer to move back one column. |
697 | * |
698 | * Locking: echo_lock to protect the echo buffer |
699 | */ |
700 | |
701 | static void echo_move_back_col(struct tty_struct *tty) |
702 | { |
703 | mutex_lock(&tty->echo_lock); |
704 | |
705 | add_echo_byte(ECHO_OP_START, tty); |
706 | add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty); |
707 | |
708 | mutex_unlock(&tty->echo_lock); |
709 | } |
710 | |
711 | /** |
712 | * echo_set_canon_col - add operation to set the canon column |
713 | * @tty: terminal device |
714 | * |
715 | * Add an operation to the echo buffer to set the canon column |
716 | * to the current column. |
717 | * |
718 | * Locking: echo_lock to protect the echo buffer |
719 | */ |
720 | |
721 | static void echo_set_canon_col(struct tty_struct *tty) |
722 | { |
723 | mutex_lock(&tty->echo_lock); |
724 | |
725 | add_echo_byte(ECHO_OP_START, tty); |
726 | add_echo_byte(ECHO_OP_SET_CANON_COL, tty); |
727 | |
728 | mutex_unlock(&tty->echo_lock); |
729 | } |
730 | |
731 | /** |
732 | * echo_erase_tab - add operation to erase a tab |
733 | * @num_chars: number of character columns already used |
734 | * @after_tab: true if num_chars starts after a previous tab |
735 | * @tty: terminal device |
736 | * |
737 | * Add an operation to the echo buffer to erase a tab. |
738 | * |
739 | * Called by the eraser function, which knows how many character |
740 | * columns have been used since either a previous tab or the start |
741 | * of input. This information will be used later, along with |
742 | * canon column (if applicable), to go back the correct number |
743 | * of columns. |
744 | * |
745 | * Locking: echo_lock to protect the echo buffer |
746 | */ |
747 | |
748 | static void echo_erase_tab(unsigned int num_chars, int after_tab, |
749 | struct tty_struct *tty) |
750 | { |
751 | mutex_lock(&tty->echo_lock); |
752 | |
753 | add_echo_byte(ECHO_OP_START, tty); |
754 | add_echo_byte(ECHO_OP_ERASE_TAB, tty); |
755 | |
756 | /* We only need to know this modulo 8 (tab spacing) */ |
757 | num_chars &= 7; |
758 | |
759 | /* Set the high bit as a flag if num_chars is after a previous tab */ |
760 | if (after_tab) |
761 | num_chars |= 0x80; |
762 | |
763 | add_echo_byte(num_chars, tty); |
764 | |
765 | mutex_unlock(&tty->echo_lock); |
766 | } |
767 | |
768 | /** |
769 | * echo_char_raw - echo a character raw |
770 | * @c: unicode byte to echo |
771 | * @tty: terminal device |
772 | * |
773 | * Echo user input back onto the screen. This must be called only when |
774 | * L_ECHO(tty) is true. Called from the driver receive_buf path. |
775 | * |
776 | * This variant does not treat control characters specially. |
777 | * |
778 | * Locking: echo_lock to protect the echo buffer |
779 | */ |
780 | |
781 | static void echo_char_raw(unsigned char c, struct tty_struct *tty) |
782 | { |
783 | mutex_lock(&tty->echo_lock); |
784 | |
785 | if (c == ECHO_OP_START) { |
786 | add_echo_byte(ECHO_OP_START, tty); |
787 | add_echo_byte(ECHO_OP_START, tty); |
788 | } else { |
789 | add_echo_byte(c, tty); |
790 | } |
791 | |
792 | mutex_unlock(&tty->echo_lock); |
793 | } |
794 | |
795 | /** |
796 | * echo_char - echo a character |
797 | * @c: unicode byte to echo |
798 | * @tty: terminal device |
799 | * |
800 | * Echo user input back onto the screen. This must be called only when |
801 | * L_ECHO(tty) is true. Called from the driver receive_buf path. |
802 | * |
803 | * This variant tags control characters to be echoed as "^X" |
804 | * (where X is the letter representing the control char). |
805 | * |
806 | * Locking: echo_lock to protect the echo buffer |
807 | */ |
808 | |
809 | static void echo_char(unsigned char c, struct tty_struct *tty) |
810 | { |
811 | mutex_lock(&tty->echo_lock); |
812 | |
813 | if (c == ECHO_OP_START) { |
814 | add_echo_byte(ECHO_OP_START, tty); |
815 | add_echo_byte(ECHO_OP_START, tty); |
816 | } else { |
817 | if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') |
818 | add_echo_byte(ECHO_OP_START, tty); |
819 | add_echo_byte(c, tty); |
820 | } |
821 | |
822 | mutex_unlock(&tty->echo_lock); |
823 | } |
824 | |
825 | /** |
826 | * finish_erasing - complete erase |
827 | * @tty: tty doing the erase |
828 | */ |
829 | |
830 | static inline void finish_erasing(struct tty_struct *tty) |
831 | { |
832 | if (tty->erasing) { |
833 | echo_char_raw('/', tty); |
834 | tty->erasing = 0; |
835 | } |
836 | } |
837 | |
838 | /** |
839 | * eraser - handle erase function |
840 | * @c: character input |
841 | * @tty: terminal device |
842 | * |
843 | * Perform erase and necessary output when an erase character is |
844 | * present in the stream from the driver layer. Handles the complexities |
845 | * of UTF-8 multibyte symbols. |
846 | * |
847 | * Locking: read_lock for tty buffers |
848 | */ |
849 | |
850 | static void eraser(unsigned char c, struct tty_struct *tty) |
851 | { |
852 | enum { ERASE, WERASE, KILL } kill_type; |
853 | int head, seen_alnums, cnt; |
854 | unsigned long flags; |
855 | |
856 | /* FIXME: locking needed ? */ |
857 | if (tty->read_head == tty->canon_head) { |
858 | /* process_output('\a', tty); */ /* what do you think? */ |
859 | return; |
860 | } |
861 | if (c == ERASE_CHAR(tty)) |
862 | kill_type = ERASE; |
863 | else if (c == WERASE_CHAR(tty)) |
864 | kill_type = WERASE; |
865 | else { |
866 | if (!L_ECHO(tty)) { |
867 | spin_lock_irqsave(&tty->read_lock, flags); |
868 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & |
869 | (N_TTY_BUF_SIZE - 1)); |
870 | tty->read_head = tty->canon_head; |
871 | spin_unlock_irqrestore(&tty->read_lock, flags); |
872 | return; |
873 | } |
874 | if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { |
875 | spin_lock_irqsave(&tty->read_lock, flags); |
876 | tty->read_cnt -= ((tty->read_head - tty->canon_head) & |
877 | (N_TTY_BUF_SIZE - 1)); |
878 | tty->read_head = tty->canon_head; |
879 | spin_unlock_irqrestore(&tty->read_lock, flags); |
880 | finish_erasing(tty); |
881 | echo_char(KILL_CHAR(tty), tty); |
882 | /* Add a newline if ECHOK is on and ECHOKE is off. */ |
883 | if (L_ECHOK(tty)) |
884 | echo_char_raw('\n', tty); |
885 | return; |
886 | } |
887 | kill_type = KILL; |
888 | } |
889 | |
890 | seen_alnums = 0; |
891 | /* FIXME: Locking ?? */ |
892 | while (tty->read_head != tty->canon_head) { |
893 | head = tty->read_head; |
894 | |
895 | /* erase a single possibly multibyte character */ |
896 | do { |
897 | head = (head - 1) & (N_TTY_BUF_SIZE-1); |
898 | c = tty->read_buf[head]; |
899 | } while (is_continuation(c, tty) && head != tty->canon_head); |
900 | |
901 | /* do not partially erase */ |
902 | if (is_continuation(c, tty)) |
903 | break; |
904 | |
905 | if (kill_type == WERASE) { |
906 | /* Equivalent to BSD's ALTWERASE. */ |
907 | if (isalnum(c) || c == '_') |
908 | seen_alnums++; |
909 | else if (seen_alnums) |
910 | break; |
911 | } |
912 | cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1); |
913 | spin_lock_irqsave(&tty->read_lock, flags); |
914 | tty->read_head = head; |
915 | tty->read_cnt -= cnt; |
916 | spin_unlock_irqrestore(&tty->read_lock, flags); |
917 | if (L_ECHO(tty)) { |
918 | if (L_ECHOPRT(tty)) { |
919 | if (!tty->erasing) { |
920 | echo_char_raw('\\', tty); |
921 | tty->erasing = 1; |
922 | } |
923 | /* if cnt > 1, output a multi-byte character */ |
924 | echo_char(c, tty); |
925 | while (--cnt > 0) { |
926 | head = (head+1) & (N_TTY_BUF_SIZE-1); |
927 | echo_char_raw(tty->read_buf[head], tty); |
928 | echo_move_back_col(tty); |
929 | } |
930 | } else if (kill_type == ERASE && !L_ECHOE(tty)) { |
931 | echo_char(ERASE_CHAR(tty), tty); |
932 | } else if (c == '\t') { |
933 | unsigned int num_chars = 0; |
934 | int after_tab = 0; |
935 | unsigned long tail = tty->read_head; |
936 | |
937 | /* |
938 | * Count the columns used for characters |
939 | * since the start of input or after a |
940 | * previous tab. |
941 | * This info is used to go back the correct |
942 | * number of columns. |
943 | */ |
944 | while (tail != tty->canon_head) { |
945 | tail = (tail-1) & (N_TTY_BUF_SIZE-1); |
946 | c = tty->read_buf[tail]; |
947 | if (c == '\t') { |
948 | after_tab = 1; |
949 | break; |
950 | } else if (iscntrl(c)) { |
951 | if (L_ECHOCTL(tty)) |
952 | num_chars += 2; |
953 | } else if (!is_continuation(c, tty)) { |
954 | num_chars++; |
955 | } |
956 | } |
957 | echo_erase_tab(num_chars, after_tab, tty); |
958 | } else { |
959 | if (iscntrl(c) && L_ECHOCTL(tty)) { |
960 | echo_char_raw('\b', tty); |
961 | echo_char_raw(' ', tty); |
962 | echo_char_raw('\b', tty); |
963 | } |
964 | if (!iscntrl(c) || L_ECHOCTL(tty)) { |
965 | echo_char_raw('\b', tty); |
966 | echo_char_raw(' ', tty); |
967 | echo_char_raw('\b', tty); |
968 | } |
969 | } |
970 | } |
971 | if (kill_type == ERASE) |
972 | break; |
973 | } |
974 | if (tty->read_head == tty->canon_head && L_ECHO(tty)) |
975 | finish_erasing(tty); |
976 | } |
977 | |
978 | /** |
979 | * isig - handle the ISIG optio |
980 | * @sig: signal |
981 | * @tty: terminal |
982 | * @flush: force flush |
983 | * |
984 | * Called when a signal is being sent due to terminal input. This |
985 | * may caus terminal flushing to take place according to the termios |
986 | * settings and character used. Called from the driver receive_buf |
987 | * path so serialized. |
988 | * |
989 | * Locking: ctrl_lock, read_lock (both via flush buffer) |
990 | */ |
991 | |
992 | static inline void isig(int sig, struct tty_struct *tty, int flush) |
993 | { |
994 | if (tty->pgrp) |
995 | kill_pgrp(tty->pgrp, sig, 1); |
996 | if (flush || !L_NOFLSH(tty)) { |
997 | n_tty_flush_buffer(tty); |
998 | tty_driver_flush_buffer(tty); |
999 | } |
1000 | } |
1001 | |
1002 | /** |
1003 | * n_tty_receive_break - handle break |
1004 | * @tty: terminal |
1005 | * |
1006 | * An RS232 break event has been hit in the incoming bitstream. This |
1007 | * can cause a variety of events depending upon the termios settings. |
1008 | * |
1009 | * Called from the receive_buf path so single threaded. |
1010 | */ |
1011 | |
1012 | static inline void n_tty_receive_break(struct tty_struct *tty) |
1013 | { |
1014 | if (I_IGNBRK(tty)) |
1015 | return; |
1016 | if (I_BRKINT(tty)) { |
1017 | isig(SIGINT, tty, 1); |
1018 | return; |
1019 | } |
1020 | if (I_PARMRK(tty)) { |
1021 | put_tty_queue('\377', tty); |
1022 | put_tty_queue('\0', tty); |
1023 | } |
1024 | put_tty_queue('\0', tty); |
1025 | wake_up_interruptible(&tty->read_wait); |
1026 | } |
1027 | |
1028 | /** |
1029 | * n_tty_receive_overrun - handle overrun reporting |
1030 | * @tty: terminal |
1031 | * |
1032 | * Data arrived faster than we could process it. While the tty |
1033 | * driver has flagged this the bits that were missed are gone |
1034 | * forever. |
1035 | * |
1036 | * Called from the receive_buf path so single threaded. Does not |
1037 | * need locking as num_overrun and overrun_time are function |
1038 | * private. |
1039 | */ |
1040 | |
1041 | static inline void n_tty_receive_overrun(struct tty_struct *tty) |
1042 | { |
1043 | char buf[64]; |
1044 | |
1045 | tty->num_overrun++; |
1046 | if (time_before(tty->overrun_time, jiffies - HZ) || |
1047 | time_after(tty->overrun_time, jiffies)) { |
1048 | printk(KERN_WARNING "%s: %d input overrun(s)\n", |
1049 | tty_name(tty, buf), |
1050 | tty->num_overrun); |
1051 | tty->overrun_time = jiffies; |
1052 | tty->num_overrun = 0; |
1053 | } |
1054 | } |
1055 | |
1056 | /** |
1057 | * n_tty_receive_parity_error - error notifier |
1058 | * @tty: terminal device |
1059 | * @c: character |
1060 | * |
1061 | * Process a parity error and queue the right data to indicate |
1062 | * the error case if necessary. Locking as per n_tty_receive_buf. |
1063 | */ |
1064 | static inline void n_tty_receive_parity_error(struct tty_struct *tty, |
1065 | unsigned char c) |
1066 | { |
1067 | if (I_IGNPAR(tty)) |
1068 | return; |
1069 | if (I_PARMRK(tty)) { |
1070 | put_tty_queue('\377', tty); |
1071 | put_tty_queue('\0', tty); |
1072 | put_tty_queue(c, tty); |
1073 | } else if (I_INPCK(tty)) |
1074 | put_tty_queue('\0', tty); |
1075 | else |
1076 | put_tty_queue(c, tty); |
1077 | wake_up_interruptible(&tty->read_wait); |
1078 | } |
1079 | |
1080 | /** |
1081 | * n_tty_receive_char - perform processing |
1082 | * @tty: terminal device |
1083 | * @c: character |
1084 | * |
1085 | * Process an individual character of input received from the driver. |
1086 | * This is serialized with respect to itself by the rules for the |
1087 | * driver above. |
1088 | */ |
1089 | |
1090 | static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) |
1091 | { |
1092 | unsigned long flags; |
1093 | int parmrk; |
1094 | |
1095 | if (tty->raw) { |
1096 | put_tty_queue(c, tty); |
1097 | return; |
1098 | } |
1099 | |
1100 | if (I_ISTRIP(tty)) |
1101 | c &= 0x7f; |
1102 | if (I_IUCLC(tty) && L_IEXTEN(tty)) |
1103 | c = tolower(c); |
1104 | |
1105 | if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && |
1106 | I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) && |
1107 | c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) { |
1108 | start_tty(tty); |
1109 | process_echoes(tty); |
1110 | } |
1111 | |
1112 | if (tty->closing) { |
1113 | if (I_IXON(tty)) { |
1114 | if (c == START_CHAR(tty)) { |
1115 | start_tty(tty); |
1116 | process_echoes(tty); |
1117 | } else if (c == STOP_CHAR(tty)) |
1118 | stop_tty(tty); |
1119 | } |
1120 | return; |
1121 | } |
1122 | |
1123 | /* |
1124 | * If the previous character was LNEXT, or we know that this |
1125 | * character is not one of the characters that we'll have to |
1126 | * handle specially, do shortcut processing to speed things |
1127 | * up. |
1128 | */ |
1129 | if (!test_bit(c, tty->process_char_map) || tty->lnext) { |
1130 | tty->lnext = 0; |
1131 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; |
1132 | if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) { |
1133 | /* beep if no space */ |
1134 | if (L_ECHO(tty)) |
1135 | process_output('\a', tty); |
1136 | return; |
1137 | } |
1138 | if (L_ECHO(tty)) { |
1139 | finish_erasing(tty); |
1140 | /* Record the column of first canon char. */ |
1141 | if (tty->canon_head == tty->read_head) |
1142 | echo_set_canon_col(tty); |
1143 | echo_char(c, tty); |
1144 | process_echoes(tty); |
1145 | } |
1146 | if (parmrk) |
1147 | put_tty_queue(c, tty); |
1148 | put_tty_queue(c, tty); |
1149 | return; |
1150 | } |
1151 | |
1152 | if (I_IXON(tty)) { |
1153 | if (c == START_CHAR(tty)) { |
1154 | start_tty(tty); |
1155 | process_echoes(tty); |
1156 | return; |
1157 | } |
1158 | if (c == STOP_CHAR(tty)) { |
1159 | stop_tty(tty); |
1160 | return; |
1161 | } |
1162 | } |
1163 | |
1164 | if (L_ISIG(tty)) { |
1165 | int signal; |
1166 | signal = SIGINT; |
1167 | if (c == INTR_CHAR(tty)) |
1168 | goto send_signal; |
1169 | signal = SIGQUIT; |
1170 | if (c == QUIT_CHAR(tty)) |
1171 | goto send_signal; |
1172 | signal = SIGTSTP; |
1173 | if (c == SUSP_CHAR(tty)) { |
1174 | send_signal: |
1175 | /* |
1176 | * Note that we do not use isig() here because we want |
1177 | * the order to be: |
1178 | * 1) flush, 2) echo, 3) signal |
1179 | */ |
1180 | if (!L_NOFLSH(tty)) { |
1181 | n_tty_flush_buffer(tty); |
1182 | tty_driver_flush_buffer(tty); |
1183 | } |
1184 | if (I_IXON(tty)) |
1185 | start_tty(tty); |
1186 | if (L_ECHO(tty)) { |
1187 | echo_char(c, tty); |
1188 | process_echoes(tty); |
1189 | } |
1190 | if (tty->pgrp) |
1191 | kill_pgrp(tty->pgrp, signal, 1); |
1192 | return; |
1193 | } |
1194 | } |
1195 | |
1196 | if (c == '\r') { |
1197 | if (I_IGNCR(tty)) |
1198 | return; |
1199 | if (I_ICRNL(tty)) |
1200 | c = '\n'; |
1201 | } else if (c == '\n' && I_INLCR(tty)) |
1202 | c = '\r'; |
1203 | |
1204 | if (tty->icanon) { |
1205 | if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || |
1206 | (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { |
1207 | eraser(c, tty); |
1208 | process_echoes(tty); |
1209 | return; |
1210 | } |
1211 | if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { |
1212 | tty->lnext = 1; |
1213 | if (L_ECHO(tty)) { |
1214 | finish_erasing(tty); |
1215 | if (L_ECHOCTL(tty)) { |
1216 | echo_char_raw('^', tty); |
1217 | echo_char_raw('\b', tty); |
1218 | process_echoes(tty); |
1219 | } |
1220 | } |
1221 | return; |
1222 | } |
1223 | if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && |
1224 | L_IEXTEN(tty)) { |
1225 | unsigned long tail = tty->canon_head; |
1226 | |
1227 | finish_erasing(tty); |
1228 | echo_char(c, tty); |
1229 | echo_char_raw('\n', tty); |
1230 | while (tail != tty->read_head) { |
1231 | echo_char(tty->read_buf[tail], tty); |
1232 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); |
1233 | } |
1234 | process_echoes(tty); |
1235 | return; |
1236 | } |
1237 | if (c == '\n') { |
1238 | if (tty->read_cnt >= N_TTY_BUF_SIZE) { |
1239 | if (L_ECHO(tty)) |
1240 | process_output('\a', tty); |
1241 | return; |
1242 | } |
1243 | if (L_ECHO(tty) || L_ECHONL(tty)) { |
1244 | echo_char_raw('\n', tty); |
1245 | process_echoes(tty); |
1246 | } |
1247 | goto handle_newline; |
1248 | } |
1249 | if (c == EOF_CHAR(tty)) { |
1250 | if (tty->read_cnt >= N_TTY_BUF_SIZE) |
1251 | return; |
1252 | if (tty->canon_head != tty->read_head) |
1253 | set_bit(TTY_PUSH, &tty->flags); |
1254 | c = __DISABLED_CHAR; |
1255 | goto handle_newline; |
1256 | } |
1257 | if ((c == EOL_CHAR(tty)) || |
1258 | (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { |
1259 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) |
1260 | ? 1 : 0; |
1261 | if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) { |
1262 | if (L_ECHO(tty)) |
1263 | process_output('\a', tty); |
1264 | return; |
1265 | } |
1266 | /* |
1267 | * XXX are EOL_CHAR and EOL2_CHAR echoed?!? |
1268 | */ |
1269 | if (L_ECHO(tty)) { |
1270 | /* Record the column of first canon char. */ |
1271 | if (tty->canon_head == tty->read_head) |
1272 | echo_set_canon_col(tty); |
1273 | echo_char(c, tty); |
1274 | process_echoes(tty); |
1275 | } |
1276 | /* |
1277 | * XXX does PARMRK doubling happen for |
1278 | * EOL_CHAR and EOL2_CHAR? |
1279 | */ |
1280 | if (parmrk) |
1281 | put_tty_queue(c, tty); |
1282 | |
1283 | handle_newline: |
1284 | spin_lock_irqsave(&tty->read_lock, flags); |
1285 | set_bit(tty->read_head, tty->read_flags); |
1286 | put_tty_queue_nolock(c, tty); |
1287 | tty->canon_head = tty->read_head; |
1288 | tty->canon_data++; |
1289 | spin_unlock_irqrestore(&tty->read_lock, flags); |
1290 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
1291 | if (waitqueue_active(&tty->read_wait)) |
1292 | wake_up_interruptible(&tty->read_wait); |
1293 | return; |
1294 | } |
1295 | } |
1296 | |
1297 | parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; |
1298 | if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) { |
1299 | /* beep if no space */ |
1300 | if (L_ECHO(tty)) |
1301 | process_output('\a', tty); |
1302 | return; |
1303 | } |
1304 | if (L_ECHO(tty)) { |
1305 | finish_erasing(tty); |
1306 | if (c == '\n') |
1307 | echo_char_raw('\n', tty); |
1308 | else { |
1309 | /* Record the column of first canon char. */ |
1310 | if (tty->canon_head == tty->read_head) |
1311 | echo_set_canon_col(tty); |
1312 | echo_char(c, tty); |
1313 | } |
1314 | process_echoes(tty); |
1315 | } |
1316 | |
1317 | if (parmrk) |
1318 | put_tty_queue(c, tty); |
1319 | |
1320 | put_tty_queue(c, tty); |
1321 | } |
1322 | |
1323 | |
1324 | /** |
1325 | * n_tty_write_wakeup - asynchronous I/O notifier |
1326 | * @tty: tty device |
1327 | * |
1328 | * Required for the ptys, serial driver etc. since processes |
1329 | * that attach themselves to the master and rely on ASYNC |
1330 | * IO must be woken up |
1331 | */ |
1332 | |
1333 | static void n_tty_write_wakeup(struct tty_struct *tty) |
1334 | { |
1335 | if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) |
1336 | kill_fasync(&tty->fasync, SIGIO, POLL_OUT); |
1337 | } |
1338 | |
1339 | /** |
1340 | * n_tty_receive_buf - data receive |
1341 | * @tty: terminal device |
1342 | * @cp: buffer |
1343 | * @fp: flag buffer |
1344 | * @count: characters |
1345 | * |
1346 | * Called by the terminal driver when a block of characters has |
1347 | * been received. This function must be called from soft contexts |
1348 | * not from interrupt context. The driver is responsible for making |
1349 | * calls one at a time and in order (or using flush_to_ldisc) |
1350 | */ |
1351 | |
1352 | static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, |
1353 | char *fp, int count) |
1354 | { |
1355 | const unsigned char *p; |
1356 | char *f, flags = TTY_NORMAL; |
1357 | int i; |
1358 | char buf[64]; |
1359 | unsigned long cpuflags; |
1360 | |
1361 | if (!tty->read_buf) |
1362 | return; |
1363 | |
1364 | if (tty->real_raw) { |
1365 | spin_lock_irqsave(&tty->read_lock, cpuflags); |
1366 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, |
1367 | N_TTY_BUF_SIZE - tty->read_head); |
1368 | i = min(count, i); |
1369 | memcpy(tty->read_buf + tty->read_head, cp, i); |
1370 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); |
1371 | tty->read_cnt += i; |
1372 | cp += i; |
1373 | count -= i; |
1374 | |
1375 | i = min(N_TTY_BUF_SIZE - tty->read_cnt, |
1376 | N_TTY_BUF_SIZE - tty->read_head); |
1377 | i = min(count, i); |
1378 | memcpy(tty->read_buf + tty->read_head, cp, i); |
1379 | tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); |
1380 | tty->read_cnt += i; |
1381 | spin_unlock_irqrestore(&tty->read_lock, cpuflags); |
1382 | } else { |
1383 | for (i = count, p = cp, f = fp; i; i--, p++) { |
1384 | if (f) |
1385 | flags = *f++; |
1386 | switch (flags) { |
1387 | case TTY_NORMAL: |
1388 | n_tty_receive_char(tty, *p); |
1389 | break; |
1390 | case TTY_BREAK: |
1391 | n_tty_receive_break(tty); |
1392 | break; |
1393 | case TTY_PARITY: |
1394 | case TTY_FRAME: |
1395 | n_tty_receive_parity_error(tty, *p); |
1396 | break; |
1397 | case TTY_OVERRUN: |
1398 | n_tty_receive_overrun(tty); |
1399 | break; |
1400 | default: |
1401 | printk(KERN_ERR "%s: unknown flag %d\n", |
1402 | tty_name(tty, buf), flags); |
1403 | break; |
1404 | } |
1405 | } |
1406 | if (tty->ops->flush_chars) |
1407 | tty->ops->flush_chars(tty); |
1408 | } |
1409 | |
1410 | n_tty_set_room(tty); |
1411 | |
1412 | if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) { |
1413 | kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
1414 | if (waitqueue_active(&tty->read_wait)) |
1415 | wake_up_interruptible(&tty->read_wait); |
1416 | } |
1417 | |
1418 | /* |
1419 | * Check the remaining room for the input canonicalization |
1420 | * mode. We don't want to throttle the driver if we're in |
1421 | * canonical mode and don't have a newline yet! |
1422 | */ |
1423 | if (tty->receive_room < TTY_THRESHOLD_THROTTLE) |
1424 | tty_throttle(tty); |
1425 | } |
1426 | |
1427 | int is_ignored(int sig) |
1428 | { |
1429 | return (sigismember(¤t->blocked, sig) || |
1430 | current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); |
1431 | } |
1432 | |
1433 | /** |
1434 | * n_tty_set_termios - termios data changed |
1435 | * @tty: terminal |
1436 | * @old: previous data |
1437 | * |
1438 | * Called by the tty layer when the user changes termios flags so |
1439 | * that the line discipline can plan ahead. This function cannot sleep |
1440 | * and is protected from re-entry by the tty layer. The user is |
1441 | * guaranteed that this function will not be re-entered or in progress |
1442 | * when the ldisc is closed. |
1443 | * |
1444 | * Locking: Caller holds tty->termios_mutex |
1445 | */ |
1446 | |
1447 | static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) |
1448 | { |
1449 | int canon_change = 1; |
1450 | BUG_ON(!tty); |
1451 | |
1452 | if (old) |
1453 | canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON; |
1454 | if (canon_change) { |
1455 | memset(&tty->read_flags, 0, sizeof tty->read_flags); |
1456 | tty->canon_head = tty->read_tail; |
1457 | tty->canon_data = 0; |
1458 | tty->erasing = 0; |
1459 | } |
1460 | |
1461 | if (canon_change && !L_ICANON(tty) && tty->read_cnt) |
1462 | wake_up_interruptible(&tty->read_wait); |
1463 | |
1464 | tty->icanon = (L_ICANON(tty) != 0); |
1465 | if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { |
1466 | tty->raw = 1; |
1467 | tty->real_raw = 1; |
1468 | n_tty_set_room(tty); |
1469 | return; |
1470 | } |
1471 | if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || |
1472 | I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || |
1473 | I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || |
1474 | I_PARMRK(tty)) { |
1475 | memset(tty->process_char_map, 0, 256/8); |
1476 | |
1477 | if (I_IGNCR(tty) || I_ICRNL(tty)) |
1478 | set_bit('\r', tty->process_char_map); |
1479 | if (I_INLCR(tty)) |
1480 | set_bit('\n', tty->process_char_map); |
1481 | |
1482 | if (L_ICANON(tty)) { |
1483 | set_bit(ERASE_CHAR(tty), tty->process_char_map); |
1484 | set_bit(KILL_CHAR(tty), tty->process_char_map); |
1485 | set_bit(EOF_CHAR(tty), tty->process_char_map); |
1486 | set_bit('\n', tty->process_char_map); |
1487 | set_bit(EOL_CHAR(tty), tty->process_char_map); |
1488 | if (L_IEXTEN(tty)) { |
1489 | set_bit(WERASE_CHAR(tty), |
1490 | tty->process_char_map); |
1491 | set_bit(LNEXT_CHAR(tty), |
1492 | tty->process_char_map); |
1493 | set_bit(EOL2_CHAR(tty), |
1494 | tty->process_char_map); |
1495 | if (L_ECHO(tty)) |
1496 | set_bit(REPRINT_CHAR(tty), |
1497 | tty->process_char_map); |
1498 | } |
1499 | } |
1500 | if (I_IXON(tty)) { |
1501 | set_bit(START_CHAR(tty), tty->process_char_map); |
1502 | set_bit(STOP_CHAR(tty), tty->process_char_map); |
1503 | } |
1504 | if (L_ISIG(tty)) { |
1505 | set_bit(INTR_CHAR(tty), tty->process_char_map); |
1506 | set_bit(QUIT_CHAR(tty), tty->process_char_map); |
1507 | set_bit(SUSP_CHAR(tty), tty->process_char_map); |
1508 | } |
1509 | clear_bit(__DISABLED_CHAR, tty->process_char_map); |
1510 | tty->raw = 0; |
1511 | tty->real_raw = 0; |
1512 | } else { |
1513 | tty->raw = 1; |
1514 | if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && |
1515 | (I_IGNPAR(tty) || !I_INPCK(tty)) && |
1516 | (tty->driver->flags & TTY_DRIVER_REAL_RAW)) |
1517 | tty->real_raw = 1; |
1518 | else |
1519 | tty->real_raw = 0; |
1520 | } |
1521 | n_tty_set_room(tty); |
1522 | /* The termios change make the tty ready for I/O */ |
1523 | wake_up_interruptible(&tty->write_wait); |
1524 | wake_up_interruptible(&tty->read_wait); |
1525 | } |
1526 | |
1527 | /** |
1528 | * n_tty_close - close the ldisc for this tty |
1529 | * @tty: device |
1530 | * |
1531 | * Called from the terminal layer when this line discipline is |
1532 | * being shut down, either because of a close or becsuse of a |
1533 | * discipline change. The function will not be called while other |
1534 | * ldisc methods are in progress. |
1535 | */ |
1536 | |
1537 | static void n_tty_close(struct tty_struct *tty) |
1538 | { |
1539 | n_tty_flush_buffer(tty); |
1540 | if (tty->read_buf) { |
1541 | kfree(tty->read_buf); |
1542 | tty->read_buf = NULL; |
1543 | } |
1544 | if (tty->echo_buf) { |
1545 | kfree(tty->echo_buf); |
1546 | tty->echo_buf = NULL; |
1547 | } |
1548 | } |
1549 | |
1550 | /** |
1551 | * n_tty_open - open an ldisc |
1552 | * @tty: terminal to open |
1553 | * |
1554 | * Called when this line discipline is being attached to the |
1555 | * terminal device. Can sleep. Called serialized so that no |
1556 | * other events will occur in parallel. No further open will occur |
1557 | * until a close. |
1558 | */ |
1559 | |
1560 | static int n_tty_open(struct tty_struct *tty) |
1561 | { |
1562 | if (!tty) |
1563 | return -EINVAL; |
1564 | |
1565 | /* These are ugly. Currently a malloc failure here can panic */ |
1566 | if (!tty->read_buf) { |
1567 | tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
1568 | if (!tty->read_buf) |
1569 | return -ENOMEM; |
1570 | } |
1571 | if (!tty->echo_buf) { |
1572 | tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
1573 | |
1574 | if (!tty->echo_buf) |
1575 | return -ENOMEM; |
1576 | } |
1577 | reset_buffer_flags(tty); |
1578 | tty->column = 0; |
1579 | n_tty_set_termios(tty, NULL); |
1580 | tty->minimum_to_wake = 1; |
1581 | tty->closing = 0; |
1582 | return 0; |
1583 | } |
1584 | |
1585 | static inline int input_available_p(struct tty_struct *tty, int amt) |
1586 | { |
1587 | tty_flush_to_ldisc(tty); |
1588 | if (tty->icanon) { |
1589 | if (tty->canon_data) |
1590 | return 1; |
1591 | } else if (tty->read_cnt >= (amt ? amt : 1)) |
1592 | return 1; |
1593 | |
1594 | return 0; |
1595 | } |
1596 | |
1597 | /** |
1598 | * copy_from_read_buf - copy read data directly |
1599 | * @tty: terminal device |
1600 | * @b: user data |
1601 | * @nr: size of data |
1602 | * |
1603 | * Helper function to speed up n_tty_read. It is only called when |
1604 | * ICANON is off; it copies characters straight from the tty queue to |
1605 | * user space directly. It can be profitably called twice; once to |
1606 | * drain the space from the tail pointer to the (physical) end of the |
1607 | * buffer, and once to drain the space from the (physical) beginning of |
1608 | * the buffer to head pointer. |
1609 | * |
1610 | * Called under the tty->atomic_read_lock sem |
1611 | * |
1612 | */ |
1613 | |
1614 | static int copy_from_read_buf(struct tty_struct *tty, |
1615 | unsigned char __user **b, |
1616 | size_t *nr) |
1617 | |
1618 | { |
1619 | int retval; |
1620 | size_t n; |
1621 | unsigned long flags; |
1622 | |
1623 | retval = 0; |
1624 | spin_lock_irqsave(&tty->read_lock, flags); |
1625 | n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail); |
1626 | n = min(*nr, n); |
1627 | spin_unlock_irqrestore(&tty->read_lock, flags); |
1628 | if (n) { |
1629 | retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n); |
1630 | n -= retval; |
1631 | tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n); |
1632 | spin_lock_irqsave(&tty->read_lock, flags); |
1633 | tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1); |
1634 | tty->read_cnt -= n; |
1635 | spin_unlock_irqrestore(&tty->read_lock, flags); |
1636 | *b += n; |
1637 | *nr -= n; |
1638 | } |
1639 | return retval; |
1640 | } |
1641 | |
1642 | extern ssize_t redirected_tty_write(struct file *, const char __user *, |
1643 | size_t, loff_t *); |
1644 | |
1645 | /** |
1646 | * job_control - check job control |
1647 | * @tty: tty |
1648 | * @file: file handle |
1649 | * |
1650 | * Perform job control management checks on this file/tty descriptor |
1651 | * and if appropriate send any needed signals and return a negative |
1652 | * error code if action should be taken. |
1653 | * |
1654 | * FIXME: |
1655 | * Locking: None - redirected write test is safe, testing |
1656 | * current->signal should possibly lock current->sighand |
1657 | * pgrp locking ? |
1658 | */ |
1659 | |
1660 | static int job_control(struct tty_struct *tty, struct file *file) |
1661 | { |
1662 | /* Job control check -- must be done at start and after |
1663 | every sleep (POSIX.1 7.1.1.4). */ |
1664 | /* NOTE: not yet done after every sleep pending a thorough |
1665 | check of the logic of this change. -- jlc */ |
1666 | /* don't stop on /dev/console */ |
1667 | if (file->f_op->write != redirected_tty_write && |
1668 | current->signal->tty == tty) { |
1669 | if (!tty->pgrp) |
1670 | printk(KERN_ERR "n_tty_read: no tty->pgrp!\n"); |
1671 | else if (task_pgrp(current) != tty->pgrp) { |
1672 | if (is_ignored(SIGTTIN) || |
1673 | is_current_pgrp_orphaned()) |
1674 | return -EIO; |
1675 | kill_pgrp(task_pgrp(current), SIGTTIN, 1); |
1676 | set_thread_flag(TIF_SIGPENDING); |
1677 | return -ERESTARTSYS; |
1678 | } |
1679 | } |
1680 | return 0; |
1681 | } |
1682 | |
1683 | |
1684 | /** |
1685 | * n_tty_read - read function for tty |
1686 | * @tty: tty device |
1687 | * @file: file object |
1688 | * @buf: userspace buffer pointer |
1689 | * @nr: size of I/O |
1690 | * |
1691 | * Perform reads for the line discipline. We are guaranteed that the |
1692 | * line discipline will not be closed under us but we may get multiple |
1693 | * parallel readers and must handle this ourselves. We may also get |
1694 | * a hangup. Always called in user context, may sleep. |
1695 | * |
1696 | * This code must be sure never to sleep through a hangup. |
1697 | */ |
1698 | |
1699 | static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, |
1700 | unsigned char __user *buf, size_t nr) |
1701 | { |
1702 | unsigned char __user *b = buf; |
1703 | DECLARE_WAITQUEUE(wait, current); |
1704 | int c; |
1705 | int minimum, time; |
1706 | ssize_t retval = 0; |
1707 | ssize_t size; |
1708 | long timeout; |
1709 | unsigned long flags; |
1710 | int packet; |
1711 | |
1712 | do_it_again: |
1713 | |
1714 | BUG_ON(!tty->read_buf); |
1715 | |
1716 | c = job_control(tty, file); |
1717 | if (c < 0) |
1718 | return c; |
1719 | |
1720 | minimum = time = 0; |
1721 | timeout = MAX_SCHEDULE_TIMEOUT; |
1722 | if (!tty->icanon) { |
1723 | time = (HZ / 10) * TIME_CHAR(tty); |
1724 | minimum = MIN_CHAR(tty); |
1725 | if (minimum) { |
1726 | if (time) |
1727 | tty->minimum_to_wake = 1; |
1728 | else if (!waitqueue_active(&tty->read_wait) || |
1729 | (tty->minimum_to_wake > minimum)) |
1730 | tty->minimum_to_wake = minimum; |
1731 | } else { |
1732 | timeout = 0; |
1733 | if (time) { |
1734 | timeout = time; |
1735 | time = 0; |
1736 | } |
1737 | tty->minimum_to_wake = minimum = 1; |
1738 | } |
1739 | } |
1740 | |
1741 | /* |
1742 | * Internal serialization of reads. |
1743 | */ |
1744 | if (file->f_flags & O_NONBLOCK) { |
1745 | if (!mutex_trylock(&tty->atomic_read_lock)) |
1746 | return -EAGAIN; |
1747 | } else { |
1748 | if (mutex_lock_interruptible(&tty->atomic_read_lock)) |
1749 | return -ERESTARTSYS; |
1750 | } |
1751 | packet = tty->packet; |
1752 | |
1753 | add_wait_queue(&tty->read_wait, &wait); |
1754 | while (nr) { |
1755 | /* First test for status change. */ |
1756 | if (packet && tty->link->ctrl_status) { |
1757 | unsigned char cs; |
1758 | if (b != buf) |
1759 | break; |
1760 | spin_lock_irqsave(&tty->link->ctrl_lock, flags); |
1761 | cs = tty->link->ctrl_status; |
1762 | tty->link->ctrl_status = 0; |
1763 | spin_unlock_irqrestore(&tty->link->ctrl_lock, flags); |
1764 | if (tty_put_user(tty, cs, b++)) { |
1765 | retval = -EFAULT; |
1766 | b--; |
1767 | break; |
1768 | } |
1769 | nr--; |
1770 | break; |
1771 | } |
1772 | /* This statement must be first before checking for input |
1773 | so that any interrupt will set the state back to |
1774 | TASK_RUNNING. */ |
1775 | set_current_state(TASK_INTERRUPTIBLE); |
1776 | |
1777 | if (((minimum - (b - buf)) < tty->minimum_to_wake) && |
1778 | ((minimum - (b - buf)) >= 1)) |
1779 | tty->minimum_to_wake = (minimum - (b - buf)); |
1780 | |
1781 | if (!input_available_p(tty, 0)) { |
1782 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
1783 | retval = -EIO; |
1784 | break; |
1785 | } |
1786 | if (tty_hung_up_p(file)) |
1787 | break; |
1788 | if (!timeout) |
1789 | break; |
1790 | if (file->f_flags & O_NONBLOCK) { |
1791 | retval = -EAGAIN; |
1792 | break; |
1793 | } |
1794 | if (signal_pending(current)) { |
1795 | retval = -ERESTARTSYS; |
1796 | break; |
1797 | } |
1798 | /* FIXME: does n_tty_set_room need locking ? */ |
1799 | n_tty_set_room(tty); |
1800 | timeout = schedule_timeout(timeout); |
1801 | continue; |
1802 | } |
1803 | __set_current_state(TASK_RUNNING); |
1804 | |
1805 | /* Deal with packet mode. */ |
1806 | if (packet && b == buf) { |
1807 | if (tty_put_user(tty, TIOCPKT_DATA, b++)) { |
1808 | retval = -EFAULT; |
1809 | b--; |
1810 | break; |
1811 | } |
1812 | nr--; |
1813 | } |
1814 | |
1815 | if (tty->icanon) { |
1816 | /* N.B. avoid overrun if nr == 0 */ |
1817 | while (nr && tty->read_cnt) { |
1818 | int eol; |
1819 | |
1820 | eol = test_and_clear_bit(tty->read_tail, |
1821 | tty->read_flags); |
1822 | c = tty->read_buf[tty->read_tail]; |
1823 | spin_lock_irqsave(&tty->read_lock, flags); |
1824 | tty->read_tail = ((tty->read_tail+1) & |
1825 | (N_TTY_BUF_SIZE-1)); |
1826 | tty->read_cnt--; |
1827 | if (eol) { |
1828 | /* this test should be redundant: |
1829 | * we shouldn't be reading data if |
1830 | * canon_data is 0 |
1831 | */ |
1832 | if (--tty->canon_data < 0) |
1833 | tty->canon_data = 0; |
1834 | } |
1835 | spin_unlock_irqrestore(&tty->read_lock, flags); |
1836 | |
1837 | if (!eol || (c != __DISABLED_CHAR)) { |
1838 | if (tty_put_user(tty, c, b++)) { |
1839 | retval = -EFAULT; |
1840 | b--; |
1841 | break; |
1842 | } |
1843 | nr--; |
1844 | } |
1845 | if (eol) { |
1846 | tty_audit_push(tty); |
1847 | break; |
1848 | } |
1849 | } |
1850 | if (retval) |
1851 | break; |
1852 | } else { |
1853 | int uncopied; |
1854 | /* The copy function takes the read lock and handles |
1855 | locking internally for this case */ |
1856 | uncopied = copy_from_read_buf(tty, &b, &nr); |
1857 | uncopied += copy_from_read_buf(tty, &b, &nr); |
1858 | if (uncopied) { |
1859 | retval = -EFAULT; |
1860 | break; |
1861 | } |
1862 | } |
1863 | |
1864 | /* If there is enough space in the read buffer now, let the |
1865 | * low-level driver know. We use n_tty_chars_in_buffer() to |
1866 | * check the buffer, as it now knows about canonical mode. |
1867 | * Otherwise, if the driver is throttled and the line is |
1868 | * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, |
1869 | * we won't get any more characters. |
1870 | */ |
1871 | if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) { |
1872 | n_tty_set_room(tty); |
1873 | check_unthrottle(tty); |
1874 | } |
1875 | |
1876 | if (b - buf >= minimum) |
1877 | break; |
1878 | if (time) |
1879 | timeout = time; |
1880 | } |
1881 | mutex_unlock(&tty->atomic_read_lock); |
1882 | remove_wait_queue(&tty->read_wait, &wait); |
1883 | |
1884 | if (!waitqueue_active(&tty->read_wait)) |
1885 | tty->minimum_to_wake = minimum; |
1886 | |
1887 | __set_current_state(TASK_RUNNING); |
1888 | size = b - buf; |
1889 | if (size) { |
1890 | retval = size; |
1891 | if (nr) |
1892 | clear_bit(TTY_PUSH, &tty->flags); |
1893 | } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) |
1894 | goto do_it_again; |
1895 | |
1896 | n_tty_set_room(tty); |
1897 | return retval; |
1898 | } |
1899 | |
1900 | /** |
1901 | * n_tty_write - write function for tty |
1902 | * @tty: tty device |
1903 | * @file: file object |
1904 | * @buf: userspace buffer pointer |
1905 | * @nr: size of I/O |
1906 | * |
1907 | * Write function of the terminal device. This is serialized with |
1908 | * respect to other write callers but not to termios changes, reads |
1909 | * and other such events. Since the receive code will echo characters, |
1910 | * thus calling driver write methods, the output_lock is used in |
1911 | * the output processing functions called here as well as in the |
1912 | * echo processing function to protect the column state and space |
1913 | * left in the buffer. |
1914 | * |
1915 | * This code must be sure never to sleep through a hangup. |
1916 | * |
1917 | * Locking: output_lock to protect column state and space left |
1918 | * (note that the process_output*() functions take this |
1919 | * lock themselves) |
1920 | */ |
1921 | |
1922 | static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, |
1923 | const unsigned char *buf, size_t nr) |
1924 | { |
1925 | const unsigned char *b = buf; |
1926 | DECLARE_WAITQUEUE(wait, current); |
1927 | int c; |
1928 | ssize_t retval = 0; |
1929 | |
1930 | /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ |
1931 | if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { |
1932 | retval = tty_check_change(tty); |
1933 | if (retval) |
1934 | return retval; |
1935 | } |
1936 | |
1937 | /* Write out any echoed characters that are still pending */ |
1938 | process_echoes(tty); |
1939 | |
1940 | add_wait_queue(&tty->write_wait, &wait); |
1941 | while (1) { |
1942 | set_current_state(TASK_INTERRUPTIBLE); |
1943 | if (signal_pending(current)) { |
1944 | retval = -ERESTARTSYS; |
1945 | break; |
1946 | } |
1947 | if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { |
1948 | retval = -EIO; |
1949 | break; |
1950 | } |
1951 | if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { |
1952 | while (nr > 0) { |
1953 | ssize_t num = process_output_block(tty, b, nr); |
1954 | if (num < 0) { |
1955 | if (num == -EAGAIN) |
1956 | break; |
1957 | retval = num; |
1958 | goto break_out; |
1959 | } |
1960 | b += num; |
1961 | nr -= num; |
1962 | if (nr == 0) |
1963 | break; |
1964 | c = *b; |
1965 | if (process_output(c, tty) < 0) |
1966 | break; |
1967 | b++; nr--; |
1968 | } |
1969 | if (tty->ops->flush_chars) |
1970 | tty->ops->flush_chars(tty); |
1971 | } else { |
1972 | while (nr > 0) { |
1973 | c = tty->ops->write(tty, b, nr); |
1974 | if (c < 0) { |
1975 | retval = c; |
1976 | goto break_out; |
1977 | } |
1978 | if (!c) |
1979 | break; |
1980 | b += c; |
1981 | nr -= c; |
1982 | } |
1983 | } |
1984 | if (!nr) |
1985 | break; |
1986 | if (file->f_flags & O_NONBLOCK) { |
1987 | retval = -EAGAIN; |
1988 | break; |
1989 | } |
1990 | schedule(); |
1991 | } |
1992 | break_out: |
1993 | __set_current_state(TASK_RUNNING); |
1994 | remove_wait_queue(&tty->write_wait, &wait); |
1995 | if (b - buf != nr && tty->fasync) |
1996 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
1997 | return (b - buf) ? b - buf : retval; |
1998 | } |
1999 | |
2000 | /** |
2001 | * n_tty_poll - poll method for N_TTY |
2002 | * @tty: terminal device |
2003 | * @file: file accessing it |
2004 | * @wait: poll table |
2005 | * |
2006 | * Called when the line discipline is asked to poll() for data or |
2007 | * for special events. This code is not serialized with respect to |
2008 | * other events save open/close. |
2009 | * |
2010 | * This code must be sure never to sleep through a hangup. |
2011 | * Called without the kernel lock held - fine |
2012 | */ |
2013 | |
2014 | static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, |
2015 | poll_table *wait) |
2016 | { |
2017 | unsigned int mask = 0; |
2018 | |
2019 | poll_wait(file, &tty->read_wait, wait); |
2020 | poll_wait(file, &tty->write_wait, wait); |
2021 | if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) |
2022 | mask |= POLLIN | POLLRDNORM; |
2023 | if (tty->packet && tty->link->ctrl_status) |
2024 | mask |= POLLPRI | POLLIN | POLLRDNORM; |
2025 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
2026 | mask |= POLLHUP; |
2027 | if (tty_hung_up_p(file)) |
2028 | mask |= POLLHUP; |
2029 | if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { |
2030 | if (MIN_CHAR(tty) && !TIME_CHAR(tty)) |
2031 | tty->minimum_to_wake = MIN_CHAR(tty); |
2032 | else |
2033 | tty->minimum_to_wake = 1; |
2034 | } |
2035 | if (tty->ops->write && !tty_is_writelocked(tty) && |
2036 | tty_chars_in_buffer(tty) < WAKEUP_CHARS && |
2037 | tty_write_room(tty) > 0) |
2038 | mask |= POLLOUT | POLLWRNORM; |
2039 | return mask; |
2040 | } |
2041 | |
2042 | static unsigned long inq_canon(struct tty_struct *tty) |
2043 | { |
2044 | int nr, head, tail; |
2045 | |
2046 | if (!tty->canon_data) |
2047 | return 0; |
2048 | head = tty->canon_head; |
2049 | tail = tty->read_tail; |
2050 | nr = (head - tail) & (N_TTY_BUF_SIZE-1); |
2051 | /* Skip EOF-chars.. */ |
2052 | while (head != tail) { |
2053 | if (test_bit(tail, tty->read_flags) && |
2054 | tty->read_buf[tail] == __DISABLED_CHAR) |
2055 | nr--; |
2056 | tail = (tail+1) & (N_TTY_BUF_SIZE-1); |
2057 | } |
2058 | return nr; |
2059 | } |
2060 | |
2061 | static int n_tty_ioctl(struct tty_struct *tty, struct file *file, |
2062 | unsigned int cmd, unsigned long arg) |
2063 | { |
2064 | int retval; |
2065 | |
2066 | switch (cmd) { |
2067 | case TIOCOUTQ: |
2068 | return put_user(tty_chars_in_buffer(tty), (int __user *) arg); |
2069 | case TIOCINQ: |
2070 | /* FIXME: Locking */ |
2071 | retval = tty->read_cnt; |
2072 | if (L_ICANON(tty)) |
2073 | retval = inq_canon(tty); |
2074 | return put_user(retval, (unsigned int __user *) arg); |
2075 | default: |
2076 | return n_tty_ioctl_helper(tty, file, cmd, arg); |
2077 | } |
2078 | } |
2079 | |
2080 | struct tty_ldisc_ops tty_ldisc_N_TTY = { |
2081 | .magic = TTY_LDISC_MAGIC, |
2082 | .name = "n_tty", |
2083 | .open = n_tty_open, |
2084 | .close = n_tty_close, |
2085 | .flush_buffer = n_tty_flush_buffer, |
2086 | .chars_in_buffer = n_tty_chars_in_buffer, |
2087 | .read = n_tty_read, |
2088 | .write = n_tty_write, |
2089 | .ioctl = n_tty_ioctl, |
2090 | .set_termios = n_tty_set_termios, |
2091 | .poll = n_tty_poll, |
2092 | .receive_buf = n_tty_receive_buf, |
2093 | .write_wakeup = n_tty_write_wakeup |
2094 | }; |
2095 | |
2096 | /** |
2097 | * n_tty_inherit_ops - inherit N_TTY methods |
2098 | * @ops: struct tty_ldisc_ops where to save N_TTY methods |
2099 | * |
2100 | * Used by a generic struct tty_ldisc_ops to easily inherit N_TTY |
2101 | * methods. |
2102 | */ |
2103 | |
2104 | void n_tty_inherit_ops(struct tty_ldisc_ops *ops) |
2105 | { |
2106 | *ops = tty_ldisc_N_TTY; |
2107 | ops->owner = NULL; |
2108 | ops->refcount = ops->flags = 0; |
2109 | } |
2110 | EXPORT_SYMBOL_GPL(n_tty_inherit_ops); |
2111 |
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