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-rw-r--r--drivers/tty/n_tty.c2128
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diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
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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
77static 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
94static 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 int old_left;
99
100 /*
101 * If we are doing input canonicalization, and there are no
102 * pending newlines, let characters through without limit, so
103 * that erase characters will be handled. Other excess
104 * characters will be beeped.
105 */
106 if (left <= 0)
107 left = tty->icanon && !tty->canon_data;
108 old_left = tty->receive_room;
109 tty->receive_room = left;
110
111 /* Did this open up the receive buffer? We may need to flip */
112 if (left && !old_left)
113 schedule_work(&tty->buf.work);
114}
115
116static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
117{
118 if (tty->read_cnt < N_TTY_BUF_SIZE) {
119 tty->read_buf[tty->read_head] = c;
120 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
121 tty->read_cnt++;
122 }
123}
124
125/**
126 * put_tty_queue - add character to tty
127 * @c: character
128 * @tty: tty device
129 *
130 * Add a character to the tty read_buf queue. This is done under the
131 * read_lock to serialize character addition and also to protect us
132 * against parallel reads or flushes
133 */
134
135static void put_tty_queue(unsigned char c, struct tty_struct *tty)
136{
137 unsigned long flags;
138 /*
139 * The problem of stomping on the buffers ends here.
140 * Why didn't anyone see this one coming? --AJK
141 */
142 spin_lock_irqsave(&tty->read_lock, flags);
143 put_tty_queue_nolock(c, tty);
144 spin_unlock_irqrestore(&tty->read_lock, flags);
145}
146
147/**
148 * check_unthrottle - allow new receive data
149 * @tty; tty device
150 *
151 * Check whether to call the driver unthrottle functions
152 *
153 * Can sleep, may be called under the atomic_read_lock mutex but
154 * this is not guaranteed.
155 */
156static void check_unthrottle(struct tty_struct *tty)
157{
158 if (tty->count)
159 tty_unthrottle(tty);
160}
161
162/**
163 * reset_buffer_flags - reset buffer state
164 * @tty: terminal to reset
165 *
166 * Reset the read buffer counters, clear the flags,
167 * and make sure the driver is unthrottled. Called
168 * from n_tty_open() and n_tty_flush_buffer().
169 *
170 * Locking: tty_read_lock for read fields.
171 */
172
173static void reset_buffer_flags(struct tty_struct *tty)
174{
175 unsigned long flags;
176
177 spin_lock_irqsave(&tty->read_lock, flags);
178 tty->read_head = tty->read_tail = tty->read_cnt = 0;
179 spin_unlock_irqrestore(&tty->read_lock, flags);
180
181 mutex_lock(&tty->echo_lock);
182 tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
183 mutex_unlock(&tty->echo_lock);
184
185 tty->canon_head = tty->canon_data = tty->erasing = 0;
186 memset(&tty->read_flags, 0, sizeof tty->read_flags);
187 n_tty_set_room(tty);
188 check_unthrottle(tty);
189}
190
191/**
192 * n_tty_flush_buffer - clean input queue
193 * @tty: terminal device
194 *
195 * Flush the input buffer. Called when the line discipline is
196 * being closed, when the tty layer wants the buffer flushed (eg
197 * at hangup) or when the N_TTY line discipline internally has to
198 * clean the pending queue (for example some signals).
199 *
200 * Locking: ctrl_lock, read_lock.
201 */
202
203static void n_tty_flush_buffer(struct tty_struct *tty)
204{
205 unsigned long flags;
206 /* clear everything and unthrottle the driver */
207 reset_buffer_flags(tty);
208
209 if (!tty->link)
210 return;
211
212 spin_lock_irqsave(&tty->ctrl_lock, flags);
213 if (tty->link->packet) {
214 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
215 wake_up_interruptible(&tty->link->read_wait);
216 }
217 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
218}
219
220/**
221 * n_tty_chars_in_buffer - report available bytes
222 * @tty: tty device
223 *
224 * Report the number of characters buffered to be delivered to user
225 * at this instant in time.
226 *
227 * Locking: read_lock
228 */
229
230static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
231{
232 unsigned long flags;
233 ssize_t n = 0;
234
235 spin_lock_irqsave(&tty->read_lock, flags);
236 if (!tty->icanon) {
237 n = tty->read_cnt;
238 } else if (tty->canon_data) {
239 n = (tty->canon_head > tty->read_tail) ?
240 tty->canon_head - tty->read_tail :
241 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
242 }
243 spin_unlock_irqrestore(&tty->read_lock, flags);
244 return n;
245}
246
247/**
248 * is_utf8_continuation - utf8 multibyte check
249 * @c: byte to check
250 *
251 * Returns true if the utf8 character 'c' is a multibyte continuation
252 * character. We use this to correctly compute the on screen size
253 * of the character when printing
254 */
255
256static inline int is_utf8_continuation(unsigned char c)
257{
258 return (c & 0xc0) == 0x80;
259}
260
261/**
262 * is_continuation - multibyte check
263 * @c: byte to check
264 *
265 * Returns true if the utf8 character 'c' is a multibyte continuation
266 * character and the terminal is in unicode mode.
267 */
268
269static inline int is_continuation(unsigned char c, struct tty_struct *tty)
270{
271 return I_IUTF8(tty) && is_utf8_continuation(c);
272}
273
274/**
275 * do_output_char - output one character
276 * @c: character (or partial unicode symbol)
277 * @tty: terminal device
278 * @space: space available in tty driver write buffer
279 *
280 * This is a helper function that handles one output character
281 * (including special characters like TAB, CR, LF, etc.),
282 * doing OPOST processing and putting the results in the
283 * tty driver's write buffer.
284 *
285 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
286 * and NLDLY. They simply aren't relevant in the world today.
287 * If you ever need them, add them here.
288 *
289 * Returns the number of bytes of buffer space used or -1 if
290 * no space left.
291 *
292 * Locking: should be called under the output_lock to protect
293 * the column state and space left in the buffer
294 */
295
296static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
297{
298 int spaces;
299
300 if (!space)
301 return -1;
302
303 switch (c) {
304 case '\n':
305 if (O_ONLRET(tty))
306 tty->column = 0;
307 if (O_ONLCR(tty)) {
308 if (space < 2)
309 return -1;
310 tty->canon_column = tty->column = 0;
311 tty->ops->write(tty, "\r\n", 2);
312 return 2;
313 }
314 tty->canon_column = tty->column;
315 break;
316 case '\r':
317 if (O_ONOCR(tty) && tty->column == 0)
318 return 0;
319 if (O_OCRNL(tty)) {
320 c = '\n';
321 if (O_ONLRET(tty))
322 tty->canon_column = tty->column = 0;
323 break;
324 }
325 tty->canon_column = tty->column = 0;
326 break;
327 case '\t':
328 spaces = 8 - (tty->column & 7);
329 if (O_TABDLY(tty) == XTABS) {
330 if (space < spaces)
331 return -1;
332 tty->column += spaces;
333 tty->ops->write(tty, " ", spaces);
334 return spaces;
335 }
336 tty->column += spaces;
337 break;
338 case '\b':
339 if (tty->column > 0)
340 tty->column--;
341 break;
342 default:
343 if (!iscntrl(c)) {
344 if (O_OLCUC(tty))
345 c = toupper(c);
346 if (!is_continuation(c, tty))
347 tty->column++;
348 }
349 break;
350 }
351
352 tty_put_char(tty, c);
353 return 1;
354}
355
356/**
357 * process_output - output post processor
358 * @c: character (or partial unicode symbol)
359 * @tty: terminal device
360 *
361 * Output one character with OPOST processing.
362 * Returns -1 when the output device is full and the character
363 * must be retried.
364 *
365 * Locking: output_lock to protect column state and space left
366 * (also, this is called from n_tty_write under the
367 * tty layer write lock)
368 */
369
370static int process_output(unsigned char c, struct tty_struct *tty)
371{
372 int space, retval;
373
374 mutex_lock(&tty->output_lock);
375
376 space = tty_write_room(tty);
377 retval = do_output_char(c, tty, space);
378
379 mutex_unlock(&tty->output_lock);
380 if (retval < 0)
381 return -1;
382 else
383 return 0;
384}
385
386/**
387 * process_output_block - block post processor
388 * @tty: terminal device
389 * @buf: character buffer
390 * @nr: number of bytes to output
391 *
392 * Output a block of characters with OPOST processing.
393 * Returns the number of characters output.
394 *
395 * This path is used to speed up block console writes, among other
396 * things when processing blocks of output data. It handles only
397 * the simple cases normally found and helps to generate blocks of
398 * symbols for the console driver and thus improve performance.
399 *
400 * Locking: output_lock to protect column state and space left
401 * (also, this is called from n_tty_write under the
402 * tty layer write lock)
403 */
404
405static ssize_t process_output_block(struct tty_struct *tty,
406 const unsigned char *buf, unsigned int nr)
407{
408 int space;
409 int i;
410 const unsigned char *cp;
411
412 mutex_lock(&tty->output_lock);
413
414 space = tty_write_room(tty);
415 if (!space) {
416 mutex_unlock(&tty->output_lock);
417 return 0;
418 }
419 if (nr > space)
420 nr = space;
421
422 for (i = 0, cp = buf; i < nr; i++, cp++) {
423 unsigned char c = *cp;
424
425 switch (c) {
426 case '\n':
427 if (O_ONLRET(tty))
428 tty->column = 0;
429 if (O_ONLCR(tty))
430 goto break_out;
431 tty->canon_column = tty->column;
432 break;
433 case '\r':
434 if (O_ONOCR(tty) && tty->column == 0)
435 goto break_out;
436 if (O_OCRNL(tty))
437 goto break_out;
438 tty->canon_column = tty->column = 0;
439 break;
440 case '\t':
441 goto break_out;
442 case '\b':
443 if (tty->column > 0)
444 tty->column--;
445 break;
446 default:
447 if (!iscntrl(c)) {
448 if (O_OLCUC(tty))
449 goto break_out;
450 if (!is_continuation(c, tty))
451 tty->column++;
452 }
453 break;
454 }
455 }
456break_out:
457 i = tty->ops->write(tty, buf, i);
458
459 mutex_unlock(&tty->output_lock);
460 return i;
461}
462
463/**
464 * process_echoes - write pending echo characters
465 * @tty: terminal device
466 *
467 * Write previously buffered echo (and other ldisc-generated)
468 * characters to the tty.
469 *
470 * Characters generated by the ldisc (including echoes) need to
471 * be buffered because the driver's write buffer can fill during
472 * heavy program output. Echoing straight to the driver will
473 * often fail under these conditions, causing lost characters and
474 * resulting mismatches of ldisc state information.
475 *
476 * Since the ldisc state must represent the characters actually sent
477 * to the driver at the time of the write, operations like certain
478 * changes in column state are also saved in the buffer and executed
479 * here.
480 *
481 * A circular fifo buffer is used so that the most recent characters
482 * are prioritized. Also, when control characters are echoed with a
483 * prefixed "^", the pair is treated atomically and thus not separated.
484 *
485 * Locking: output_lock to protect column state and space left,
486 * echo_lock to protect the echo buffer
487 */
488
489static void process_echoes(struct tty_struct *tty)
490{
491 int space, nr;
492 unsigned char c;
493 unsigned char *cp, *buf_end;
494
495 if (!tty->echo_cnt)
496 return;
497
498 mutex_lock(&tty->output_lock);
499 mutex_lock(&tty->echo_lock);
500
501 space = tty_write_room(tty);
502
503 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
504 cp = tty->echo_buf + tty->echo_pos;
505 nr = tty->echo_cnt;
506 while (nr > 0) {
507 c = *cp;
508 if (c == ECHO_OP_START) {
509 unsigned char op;
510 unsigned char *opp;
511 int no_space_left = 0;
512
513 /*
514 * If the buffer byte is the start of a multi-byte
515 * operation, get the next byte, which is either the
516 * op code or a control character value.
517 */
518 opp = cp + 1;
519 if (opp == buf_end)
520 opp -= N_TTY_BUF_SIZE;
521 op = *opp;
522
523 switch (op) {
524 unsigned int num_chars, num_bs;
525
526 case ECHO_OP_ERASE_TAB:
527 if (++opp == buf_end)
528 opp -= N_TTY_BUF_SIZE;
529 num_chars = *opp;
530
531 /*
532 * Determine how many columns to go back
533 * in order to erase the tab.
534 * This depends on the number of columns
535 * used by other characters within the tab
536 * area. If this (modulo 8) count is from
537 * the start of input rather than from a
538 * previous tab, we offset by canon column.
539 * Otherwise, tab spacing is normal.
540 */
541 if (!(num_chars & 0x80))
542 num_chars += tty->canon_column;
543 num_bs = 8 - (num_chars & 7);
544
545 if (num_bs > space) {
546 no_space_left = 1;
547 break;
548 }
549 space -= num_bs;
550 while (num_bs--) {
551 tty_put_char(tty, '\b');
552 if (tty->column > 0)
553 tty->column--;
554 }
555 cp += 3;
556 nr -= 3;
557 break;
558
559 case ECHO_OP_SET_CANON_COL:
560 tty->canon_column = tty->column;
561 cp += 2;
562 nr -= 2;
563 break;
564
565 case ECHO_OP_MOVE_BACK_COL:
566 if (tty->column > 0)
567 tty->column--;
568 cp += 2;
569 nr -= 2;
570 break;
571
572 case ECHO_OP_START:
573 /* This is an escaped echo op start code */
574 if (!space) {
575 no_space_left = 1;
576 break;
577 }
578 tty_put_char(tty, ECHO_OP_START);
579 tty->column++;
580 space--;
581 cp += 2;
582 nr -= 2;
583 break;
584
585 default:
586 /*
587 * If the op is not a special byte code,
588 * it is a ctrl char tagged to be echoed
589 * as "^X" (where X is the letter
590 * representing the control char).
591 * Note that we must ensure there is
592 * enough space for the whole ctrl pair.
593 *
594 */
595 if (space < 2) {
596 no_space_left = 1;
597 break;
598 }
599 tty_put_char(tty, '^');
600 tty_put_char(tty, op ^ 0100);
601 tty->column += 2;
602 space -= 2;
603 cp += 2;
604 nr -= 2;
605 }
606
607 if (no_space_left)
608 break;
609 } else {
610 if (O_OPOST(tty) &&
611 !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
612 int retval = do_output_char(c, tty, space);
613 if (retval < 0)
614 break;
615 space -= retval;
616 } else {
617 if (!space)
618 break;
619 tty_put_char(tty, c);
620 space -= 1;
621 }
622 cp += 1;
623 nr -= 1;
624 }
625
626 /* When end of circular buffer reached, wrap around */
627 if (cp >= buf_end)
628 cp -= N_TTY_BUF_SIZE;
629 }
630
631 if (nr == 0) {
632 tty->echo_pos = 0;
633 tty->echo_cnt = 0;
634 tty->echo_overrun = 0;
635 } else {
636 int num_processed = tty->echo_cnt - nr;
637 tty->echo_pos += num_processed;
638 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
639 tty->echo_cnt = nr;
640 if (num_processed > 0)
641 tty->echo_overrun = 0;
642 }
643
644 mutex_unlock(&tty->echo_lock);
645 mutex_unlock(&tty->output_lock);
646
647 if (tty->ops->flush_chars)
648 tty->ops->flush_chars(tty);
649}
650
651/**
652 * add_echo_byte - add a byte to the echo buffer
653 * @c: unicode byte to echo
654 * @tty: terminal device
655 *
656 * Add a character or operation byte to the echo buffer.
657 *
658 * Should be called under the echo lock to protect the echo buffer.
659 */
660
661static void add_echo_byte(unsigned char c, struct tty_struct *tty)
662{
663 int new_byte_pos;
664
665 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
666 /* Circular buffer is already at capacity */
667 new_byte_pos = tty->echo_pos;
668
669 /*
670 * Since the buffer start position needs to be advanced,
671 * be sure to step by a whole operation byte group.
672 */
673 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
674 if (tty->echo_buf[(tty->echo_pos + 1) &
675 (N_TTY_BUF_SIZE - 1)] ==
676 ECHO_OP_ERASE_TAB) {
677 tty->echo_pos += 3;
678 tty->echo_cnt -= 2;
679 } else {
680 tty->echo_pos += 2;
681 tty->echo_cnt -= 1;
682 }
683 } else {
684 tty->echo_pos++;
685 }
686 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
687
688 tty->echo_overrun = 1;
689 } else {
690 new_byte_pos = tty->echo_pos + tty->echo_cnt;
691 new_byte_pos &= N_TTY_BUF_SIZE - 1;
692 tty->echo_cnt++;
693 }
694
695 tty->echo_buf[new_byte_pos] = c;
696}
697
698/**
699 * echo_move_back_col - add operation to move back a column
700 * @tty: terminal device
701 *
702 * Add an operation to the echo buffer to move back one column.
703 *
704 * Locking: echo_lock to protect the echo buffer
705 */
706
707static void echo_move_back_col(struct tty_struct *tty)
708{
709 mutex_lock(&tty->echo_lock);
710
711 add_echo_byte(ECHO_OP_START, tty);
712 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
713
714 mutex_unlock(&tty->echo_lock);
715}
716
717/**
718 * echo_set_canon_col - add operation to set the canon column
719 * @tty: terminal device
720 *
721 * Add an operation to the echo buffer to set the canon column
722 * to the current column.
723 *
724 * Locking: echo_lock to protect the echo buffer
725 */
726
727static void echo_set_canon_col(struct tty_struct *tty)
728{
729 mutex_lock(&tty->echo_lock);
730
731 add_echo_byte(ECHO_OP_START, tty);
732 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
733
734 mutex_unlock(&tty->echo_lock);
735}
736
737/**
738 * echo_erase_tab - add operation to erase a tab
739 * @num_chars: number of character columns already used
740 * @after_tab: true if num_chars starts after a previous tab
741 * @tty: terminal device
742 *
743 * Add an operation to the echo buffer to erase a tab.
744 *
745 * Called by the eraser function, which knows how many character
746 * columns have been used since either a previous tab or the start
747 * of input. This information will be used later, along with
748 * canon column (if applicable), to go back the correct number
749 * of columns.
750 *
751 * Locking: echo_lock to protect the echo buffer
752 */
753
754static void echo_erase_tab(unsigned int num_chars, int after_tab,
755 struct tty_struct *tty)
756{
757 mutex_lock(&tty->echo_lock);
758
759 add_echo_byte(ECHO_OP_START, tty);
760 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
761
762 /* We only need to know this modulo 8 (tab spacing) */
763 num_chars &= 7;
764
765 /* Set the high bit as a flag if num_chars is after a previous tab */
766 if (after_tab)
767 num_chars |= 0x80;
768
769 add_echo_byte(num_chars, tty);
770
771 mutex_unlock(&tty->echo_lock);
772}
773
774/**
775 * echo_char_raw - echo a character raw
776 * @c: unicode byte to echo
777 * @tty: terminal device
778 *
779 * Echo user input back onto the screen. This must be called only when
780 * L_ECHO(tty) is true. Called from the driver receive_buf path.
781 *
782 * This variant does not treat control characters specially.
783 *
784 * Locking: echo_lock to protect the echo buffer
785 */
786
787static void echo_char_raw(unsigned char c, struct tty_struct *tty)
788{
789 mutex_lock(&tty->echo_lock);
790
791 if (c == ECHO_OP_START) {
792 add_echo_byte(ECHO_OP_START, tty);
793 add_echo_byte(ECHO_OP_START, tty);
794 } else {
795 add_echo_byte(c, tty);
796 }
797
798 mutex_unlock(&tty->echo_lock);
799}
800
801/**
802 * echo_char - echo a character
803 * @c: unicode byte to echo
804 * @tty: terminal device
805 *
806 * Echo user input back onto the screen. This must be called only when
807 * L_ECHO(tty) is true. Called from the driver receive_buf path.
808 *
809 * This variant tags control characters to be echoed as "^X"
810 * (where X is the letter representing the control char).
811 *
812 * Locking: echo_lock to protect the echo buffer
813 */
814
815static void echo_char(unsigned char c, struct tty_struct *tty)
816{
817 mutex_lock(&tty->echo_lock);
818
819 if (c == ECHO_OP_START) {
820 add_echo_byte(ECHO_OP_START, tty);
821 add_echo_byte(ECHO_OP_START, tty);
822 } else {
823 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
824 add_echo_byte(ECHO_OP_START, tty);
825 add_echo_byte(c, tty);
826 }
827
828 mutex_unlock(&tty->echo_lock);
829}
830
831/**
832 * finish_erasing - complete erase
833 * @tty: tty doing the erase
834 */
835
836static inline void finish_erasing(struct tty_struct *tty)
837{
838 if (tty->erasing) {
839 echo_char_raw('/', tty);
840 tty->erasing = 0;
841 }
842}
843
844/**
845 * eraser - handle erase function
846 * @c: character input
847 * @tty: terminal device
848 *
849 * Perform erase and necessary output when an erase character is
850 * present in the stream from the driver layer. Handles the complexities
851 * of UTF-8 multibyte symbols.
852 *
853 * Locking: read_lock for tty buffers
854 */
855
856static void eraser(unsigned char c, struct tty_struct *tty)
857{
858 enum { ERASE, WERASE, KILL } kill_type;
859 int head, seen_alnums, cnt;
860 unsigned long flags;
861
862 /* FIXME: locking needed ? */
863 if (tty->read_head == tty->canon_head) {
864 /* process_output('\a', tty); */ /* what do you think? */
865 return;
866 }
867 if (c == ERASE_CHAR(tty))
868 kill_type = ERASE;
869 else if (c == WERASE_CHAR(tty))
870 kill_type = WERASE;
871 else {
872 if (!L_ECHO(tty)) {
873 spin_lock_irqsave(&tty->read_lock, flags);
874 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
875 (N_TTY_BUF_SIZE - 1));
876 tty->read_head = tty->canon_head;
877 spin_unlock_irqrestore(&tty->read_lock, flags);
878 return;
879 }
880 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
881 spin_lock_irqsave(&tty->read_lock, flags);
882 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
883 (N_TTY_BUF_SIZE - 1));
884 tty->read_head = tty->canon_head;
885 spin_unlock_irqrestore(&tty->read_lock, flags);
886 finish_erasing(tty);
887 echo_char(KILL_CHAR(tty), tty);
888 /* Add a newline if ECHOK is on and ECHOKE is off. */
889 if (L_ECHOK(tty))
890 echo_char_raw('\n', tty);
891 return;
892 }
893 kill_type = KILL;
894 }
895
896 seen_alnums = 0;
897 /* FIXME: Locking ?? */
898 while (tty->read_head != tty->canon_head) {
899 head = tty->read_head;
900
901 /* erase a single possibly multibyte character */
902 do {
903 head = (head - 1) & (N_TTY_BUF_SIZE-1);
904 c = tty->read_buf[head];
905 } while (is_continuation(c, tty) && head != tty->canon_head);
906
907 /* do not partially erase */
908 if (is_continuation(c, tty))
909 break;
910
911 if (kill_type == WERASE) {
912 /* Equivalent to BSD's ALTWERASE. */
913 if (isalnum(c) || c == '_')
914 seen_alnums++;
915 else if (seen_alnums)
916 break;
917 }
918 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
919 spin_lock_irqsave(&tty->read_lock, flags);
920 tty->read_head = head;
921 tty->read_cnt -= cnt;
922 spin_unlock_irqrestore(&tty->read_lock, flags);
923 if (L_ECHO(tty)) {
924 if (L_ECHOPRT(tty)) {
925 if (!tty->erasing) {
926 echo_char_raw('\\', tty);
927 tty->erasing = 1;
928 }
929 /* if cnt > 1, output a multi-byte character */
930 echo_char(c, tty);
931 while (--cnt > 0) {
932 head = (head+1) & (N_TTY_BUF_SIZE-1);
933 echo_char_raw(tty->read_buf[head], tty);
934 echo_move_back_col(tty);
935 }
936 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
937 echo_char(ERASE_CHAR(tty), tty);
938 } else if (c == '\t') {
939 unsigned int num_chars = 0;
940 int after_tab = 0;
941 unsigned long tail = tty->read_head;
942
943 /*
944 * Count the columns used for characters
945 * since the start of input or after a
946 * previous tab.
947 * This info is used to go back the correct
948 * number of columns.
949 */
950 while (tail != tty->canon_head) {
951 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
952 c = tty->read_buf[tail];
953 if (c == '\t') {
954 after_tab = 1;
955 break;
956 } else if (iscntrl(c)) {
957 if (L_ECHOCTL(tty))
958 num_chars += 2;
959 } else if (!is_continuation(c, tty)) {
960 num_chars++;
961 }
962 }
963 echo_erase_tab(num_chars, after_tab, tty);
964 } else {
965 if (iscntrl(c) && L_ECHOCTL(tty)) {
966 echo_char_raw('\b', tty);
967 echo_char_raw(' ', tty);
968 echo_char_raw('\b', tty);
969 }
970 if (!iscntrl(c) || L_ECHOCTL(tty)) {
971 echo_char_raw('\b', tty);
972 echo_char_raw(' ', tty);
973 echo_char_raw('\b', tty);
974 }
975 }
976 }
977 if (kill_type == ERASE)
978 break;
979 }
980 if (tty->read_head == tty->canon_head && L_ECHO(tty))
981 finish_erasing(tty);
982}
983
984/**
985 * isig - handle the ISIG optio
986 * @sig: signal
987 * @tty: terminal
988 * @flush: force flush
989 *
990 * Called when a signal is being sent due to terminal input. This
991 * may caus terminal flushing to take place according to the termios
992 * settings and character used. Called from the driver receive_buf
993 * path so serialized.
994 *
995 * Locking: ctrl_lock, read_lock (both via flush buffer)
996 */
997
998static inline void isig(int sig, struct tty_struct *tty, int flush)
999{
1000 if (tty->pgrp)
1001 kill_pgrp(tty->pgrp, sig, 1);
1002 if (flush || !L_NOFLSH(tty)) {
1003 n_tty_flush_buffer(tty);
1004 tty_driver_flush_buffer(tty);
1005 }
1006}
1007
1008/**
1009 * n_tty_receive_break - handle break
1010 * @tty: terminal
1011 *
1012 * An RS232 break event has been hit in the incoming bitstream. This
1013 * can cause a variety of events depending upon the termios settings.
1014 *
1015 * Called from the receive_buf path so single threaded.
1016 */
1017
1018static inline void n_tty_receive_break(struct tty_struct *tty)
1019{
1020 if (I_IGNBRK(tty))
1021 return;
1022 if (I_BRKINT(tty)) {
1023 isig(SIGINT, tty, 1);
1024 return;
1025 }
1026 if (I_PARMRK(tty)) {
1027 put_tty_queue('\377', tty);
1028 put_tty_queue('\0', tty);
1029 }
1030 put_tty_queue('\0', tty);
1031 wake_up_interruptible(&tty->read_wait);
1032}
1033
1034/**
1035 * n_tty_receive_overrun - handle overrun reporting
1036 * @tty: terminal
1037 *
1038 * Data arrived faster than we could process it. While the tty
1039 * driver has flagged this the bits that were missed are gone
1040 * forever.
1041 *
1042 * Called from the receive_buf path so single threaded. Does not
1043 * need locking as num_overrun and overrun_time are function
1044 * private.
1045 */
1046
1047static inline void n_tty_receive_overrun(struct tty_struct *tty)
1048{
1049 char buf[64];
1050
1051 tty->num_overrun++;
1052 if (time_before(tty->overrun_time, jiffies - HZ) ||
1053 time_after(tty->overrun_time, jiffies)) {
1054 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1055 tty_name(tty, buf),
1056 tty->num_overrun);
1057 tty->overrun_time = jiffies;
1058 tty->num_overrun = 0;
1059 }
1060}
1061
1062/**
1063 * n_tty_receive_parity_error - error notifier
1064 * @tty: terminal device
1065 * @c: character
1066 *
1067 * Process a parity error and queue the right data to indicate
1068 * the error case if necessary. Locking as per n_tty_receive_buf.
1069 */
1070static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1071 unsigned char c)
1072{
1073 if (I_IGNPAR(tty))
1074 return;
1075 if (I_PARMRK(tty)) {
1076 put_tty_queue('\377', tty);
1077 put_tty_queue('\0', tty);
1078 put_tty_queue(c, tty);
1079 } else if (I_INPCK(tty))
1080 put_tty_queue('\0', tty);
1081 else
1082 put_tty_queue(c, tty);
1083 wake_up_interruptible(&tty->read_wait);
1084}
1085
1086/**
1087 * n_tty_receive_char - perform processing
1088 * @tty: terminal device
1089 * @c: character
1090 *
1091 * Process an individual character of input received from the driver.
1092 * This is serialized with respect to itself by the rules for the
1093 * driver above.
1094 */
1095
1096static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1097{
1098 unsigned long flags;
1099 int parmrk;
1100
1101 if (tty->raw) {
1102 put_tty_queue(c, tty);
1103 return;
1104 }
1105
1106 if (I_ISTRIP(tty))
1107 c &= 0x7f;
1108 if (I_IUCLC(tty) && L_IEXTEN(tty))
1109 c = tolower(c);
1110
1111 if (L_EXTPROC(tty)) {
1112 put_tty_queue(c, tty);
1113 return;
1114 }
1115
1116 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1117 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1118 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1119 start_tty(tty);
1120 process_echoes(tty);
1121 }
1122
1123 if (tty->closing) {
1124 if (I_IXON(tty)) {
1125 if (c == START_CHAR(tty)) {
1126 start_tty(tty);
1127 process_echoes(tty);
1128 } else if (c == STOP_CHAR(tty))
1129 stop_tty(tty);
1130 }
1131 return;
1132 }
1133
1134 /*
1135 * If the previous character was LNEXT, or we know that this
1136 * character is not one of the characters that we'll have to
1137 * handle specially, do shortcut processing to speed things
1138 * up.
1139 */
1140 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1141 tty->lnext = 0;
1142 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1143 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1144 /* beep if no space */
1145 if (L_ECHO(tty))
1146 process_output('\a', tty);
1147 return;
1148 }
1149 if (L_ECHO(tty)) {
1150 finish_erasing(tty);
1151 /* Record the column of first canon char. */
1152 if (tty->canon_head == tty->read_head)
1153 echo_set_canon_col(tty);
1154 echo_char(c, tty);
1155 process_echoes(tty);
1156 }
1157 if (parmrk)
1158 put_tty_queue(c, tty);
1159 put_tty_queue(c, tty);
1160 return;
1161 }
1162
1163 if (I_IXON(tty)) {
1164 if (c == START_CHAR(tty)) {
1165 start_tty(tty);
1166 process_echoes(tty);
1167 return;
1168 }
1169 if (c == STOP_CHAR(tty)) {
1170 stop_tty(tty);
1171 return;
1172 }
1173 }
1174
1175 if (L_ISIG(tty)) {
1176 int signal;
1177 signal = SIGINT;
1178 if (c == INTR_CHAR(tty))
1179 goto send_signal;
1180 signal = SIGQUIT;
1181 if (c == QUIT_CHAR(tty))
1182 goto send_signal;
1183 signal = SIGTSTP;
1184 if (c == SUSP_CHAR(tty)) {
1185send_signal:
1186 /*
1187 * Note that we do not use isig() here because we want
1188 * the order to be:
1189 * 1) flush, 2) echo, 3) signal
1190 */
1191 if (!L_NOFLSH(tty)) {
1192 n_tty_flush_buffer(tty);
1193 tty_driver_flush_buffer(tty);
1194 }
1195 if (I_IXON(tty))
1196 start_tty(tty);
1197 if (L_ECHO(tty)) {
1198 echo_char(c, tty);
1199 process_echoes(tty);
1200 }
1201 if (tty->pgrp)
1202 kill_pgrp(tty->pgrp, signal, 1);
1203 return;
1204 }
1205 }
1206
1207 if (c == '\r') {
1208 if (I_IGNCR(tty))
1209 return;
1210 if (I_ICRNL(tty))
1211 c = '\n';
1212 } else if (c == '\n' && I_INLCR(tty))
1213 c = '\r';
1214
1215 if (tty->icanon) {
1216 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1217 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1218 eraser(c, tty);
1219 process_echoes(tty);
1220 return;
1221 }
1222 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1223 tty->lnext = 1;
1224 if (L_ECHO(tty)) {
1225 finish_erasing(tty);
1226 if (L_ECHOCTL(tty)) {
1227 echo_char_raw('^', tty);
1228 echo_char_raw('\b', tty);
1229 process_echoes(tty);
1230 }
1231 }
1232 return;
1233 }
1234 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1235 L_IEXTEN(tty)) {
1236 unsigned long tail = tty->canon_head;
1237
1238 finish_erasing(tty);
1239 echo_char(c, tty);
1240 echo_char_raw('\n', tty);
1241 while (tail != tty->read_head) {
1242 echo_char(tty->read_buf[tail], tty);
1243 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1244 }
1245 process_echoes(tty);
1246 return;
1247 }
1248 if (c == '\n') {
1249 if (tty->read_cnt >= N_TTY_BUF_SIZE) {
1250 if (L_ECHO(tty))
1251 process_output('\a', tty);
1252 return;
1253 }
1254 if (L_ECHO(tty) || L_ECHONL(tty)) {
1255 echo_char_raw('\n', tty);
1256 process_echoes(tty);
1257 }
1258 goto handle_newline;
1259 }
1260 if (c == EOF_CHAR(tty)) {
1261 if (tty->read_cnt >= N_TTY_BUF_SIZE)
1262 return;
1263 if (tty->canon_head != tty->read_head)
1264 set_bit(TTY_PUSH, &tty->flags);
1265 c = __DISABLED_CHAR;
1266 goto handle_newline;
1267 }
1268 if ((c == EOL_CHAR(tty)) ||
1269 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1270 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1271 ? 1 : 0;
1272 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
1273 if (L_ECHO(tty))
1274 process_output('\a', tty);
1275 return;
1276 }
1277 /*
1278 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1279 */
1280 if (L_ECHO(tty)) {
1281 /* Record the column of first canon char. */
1282 if (tty->canon_head == tty->read_head)
1283 echo_set_canon_col(tty);
1284 echo_char(c, tty);
1285 process_echoes(tty);
1286 }
1287 /*
1288 * XXX does PARMRK doubling happen for
1289 * EOL_CHAR and EOL2_CHAR?
1290 */
1291 if (parmrk)
1292 put_tty_queue(c, tty);
1293
1294handle_newline:
1295 spin_lock_irqsave(&tty->read_lock, flags);
1296 set_bit(tty->read_head, tty->read_flags);
1297 put_tty_queue_nolock(c, tty);
1298 tty->canon_head = tty->read_head;
1299 tty->canon_data++;
1300 spin_unlock_irqrestore(&tty->read_lock, flags);
1301 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1302 if (waitqueue_active(&tty->read_wait))
1303 wake_up_interruptible(&tty->read_wait);
1304 return;
1305 }
1306 }
1307
1308 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1309 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1310 /* beep if no space */
1311 if (L_ECHO(tty))
1312 process_output('\a', tty);
1313 return;
1314 }
1315 if (L_ECHO(tty)) {
1316 finish_erasing(tty);
1317 if (c == '\n')
1318 echo_char_raw('\n', tty);
1319 else {
1320 /* Record the column of first canon char. */
1321 if (tty->canon_head == tty->read_head)
1322 echo_set_canon_col(tty);
1323 echo_char(c, tty);
1324 }
1325 process_echoes(tty);
1326 }
1327
1328 if (parmrk)
1329 put_tty_queue(c, tty);
1330
1331 put_tty_queue(c, tty);
1332}
1333
1334
1335/**
1336 * n_tty_write_wakeup - asynchronous I/O notifier
1337 * @tty: tty device
1338 *
1339 * Required for the ptys, serial driver etc. since processes
1340 * that attach themselves to the master and rely on ASYNC
1341 * IO must be woken up
1342 */
1343
1344static void n_tty_write_wakeup(struct tty_struct *tty)
1345{
1346 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
1347 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1348}
1349
1350/**
1351 * n_tty_receive_buf - data receive
1352 * @tty: terminal device
1353 * @cp: buffer
1354 * @fp: flag buffer
1355 * @count: characters
1356 *
1357 * Called by the terminal driver when a block of characters has
1358 * been received. This function must be called from soft contexts
1359 * not from interrupt context. The driver is responsible for making
1360 * calls one at a time and in order (or using flush_to_ldisc)
1361 */
1362
1363static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1364 char *fp, int count)
1365{
1366 const unsigned char *p;
1367 char *f, flags = TTY_NORMAL;
1368 int i;
1369 char buf[64];
1370 unsigned long cpuflags;
1371
1372 if (!tty->read_buf)
1373 return;
1374
1375 if (tty->real_raw) {
1376 spin_lock_irqsave(&tty->read_lock, cpuflags);
1377 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1378 N_TTY_BUF_SIZE - tty->read_head);
1379 i = min(count, i);
1380 memcpy(tty->read_buf + tty->read_head, cp, i);
1381 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1382 tty->read_cnt += i;
1383 cp += i;
1384 count -= i;
1385
1386 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1387 N_TTY_BUF_SIZE - tty->read_head);
1388 i = min(count, i);
1389 memcpy(tty->read_buf + tty->read_head, cp, i);
1390 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1391 tty->read_cnt += i;
1392 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1393 } else {
1394 for (i = count, p = cp, f = fp; i; i--, p++) {
1395 if (f)
1396 flags = *f++;
1397 switch (flags) {
1398 case TTY_NORMAL:
1399 n_tty_receive_char(tty, *p);
1400 break;
1401 case TTY_BREAK:
1402 n_tty_receive_break(tty);
1403 break;
1404 case TTY_PARITY:
1405 case TTY_FRAME:
1406 n_tty_receive_parity_error(tty, *p);
1407 break;
1408 case TTY_OVERRUN:
1409 n_tty_receive_overrun(tty);
1410 break;
1411 default:
1412 printk(KERN_ERR "%s: unknown flag %d\n",
1413 tty_name(tty, buf), flags);
1414 break;
1415 }
1416 }
1417 if (tty->ops->flush_chars)
1418 tty->ops->flush_chars(tty);
1419 }
1420
1421 n_tty_set_room(tty);
1422
1423 if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
1424 L_EXTPROC(tty)) {
1425 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1426 if (waitqueue_active(&tty->read_wait))
1427 wake_up_interruptible(&tty->read_wait);
1428 }
1429
1430 /*
1431 * Check the remaining room for the input canonicalization
1432 * mode. We don't want to throttle the driver if we're in
1433 * canonical mode and don't have a newline yet!
1434 */
1435 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1436 tty_throttle(tty);
1437}
1438
1439int is_ignored(int sig)
1440{
1441 return (sigismember(&current->blocked, sig) ||
1442 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1443}
1444
1445/**
1446 * n_tty_set_termios - termios data changed
1447 * @tty: terminal
1448 * @old: previous data
1449 *
1450 * Called by the tty layer when the user changes termios flags so
1451 * that the line discipline can plan ahead. This function cannot sleep
1452 * and is protected from re-entry by the tty layer. The user is
1453 * guaranteed that this function will not be re-entered or in progress
1454 * when the ldisc is closed.
1455 *
1456 * Locking: Caller holds tty->termios_mutex
1457 */
1458
1459static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1460{
1461 int canon_change = 1;
1462 BUG_ON(!tty);
1463
1464 if (old)
1465 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1466 if (canon_change) {
1467 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1468 tty->canon_head = tty->read_tail;
1469 tty->canon_data = 0;
1470 tty->erasing = 0;
1471 }
1472
1473 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1474 wake_up_interruptible(&tty->read_wait);
1475
1476 tty->icanon = (L_ICANON(tty) != 0);
1477 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1478 tty->raw = 1;
1479 tty->real_raw = 1;
1480 n_tty_set_room(tty);
1481 return;
1482 }
1483 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1484 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1485 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1486 I_PARMRK(tty)) {
1487 memset(tty->process_char_map, 0, 256/8);
1488
1489 if (I_IGNCR(tty) || I_ICRNL(tty))
1490 set_bit('\r', tty->process_char_map);
1491 if (I_INLCR(tty))
1492 set_bit('\n', tty->process_char_map);
1493
1494 if (L_ICANON(tty)) {
1495 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1496 set_bit(KILL_CHAR(tty), tty->process_char_map);
1497 set_bit(EOF_CHAR(tty), tty->process_char_map);
1498 set_bit('\n', tty->process_char_map);
1499 set_bit(EOL_CHAR(tty), tty->process_char_map);
1500 if (L_IEXTEN(tty)) {
1501 set_bit(WERASE_CHAR(tty),
1502 tty->process_char_map);
1503 set_bit(LNEXT_CHAR(tty),
1504 tty->process_char_map);
1505 set_bit(EOL2_CHAR(tty),
1506 tty->process_char_map);
1507 if (L_ECHO(tty))
1508 set_bit(REPRINT_CHAR(tty),
1509 tty->process_char_map);
1510 }
1511 }
1512 if (I_IXON(tty)) {
1513 set_bit(START_CHAR(tty), tty->process_char_map);
1514 set_bit(STOP_CHAR(tty), tty->process_char_map);
1515 }
1516 if (L_ISIG(tty)) {
1517 set_bit(INTR_CHAR(tty), tty->process_char_map);
1518 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1519 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1520 }
1521 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1522 tty->raw = 0;
1523 tty->real_raw = 0;
1524 } else {
1525 tty->raw = 1;
1526 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1527 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1528 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1529 tty->real_raw = 1;
1530 else
1531 tty->real_raw = 0;
1532 }
1533 n_tty_set_room(tty);
1534 /* The termios change make the tty ready for I/O */
1535 wake_up_interruptible(&tty->write_wait);
1536 wake_up_interruptible(&tty->read_wait);
1537}
1538
1539/**
1540 * n_tty_close - close the ldisc for this tty
1541 * @tty: device
1542 *
1543 * Called from the terminal layer when this line discipline is
1544 * being shut down, either because of a close or becsuse of a
1545 * discipline change. The function will not be called while other
1546 * ldisc methods are in progress.
1547 */
1548
1549static void n_tty_close(struct tty_struct *tty)
1550{
1551 n_tty_flush_buffer(tty);
1552 if (tty->read_buf) {
1553 kfree(tty->read_buf);
1554 tty->read_buf = NULL;
1555 }
1556 if (tty->echo_buf) {
1557 kfree(tty->echo_buf);
1558 tty->echo_buf = NULL;
1559 }
1560}
1561
1562/**
1563 * n_tty_open - open an ldisc
1564 * @tty: terminal to open
1565 *
1566 * Called when this line discipline is being attached to the
1567 * terminal device. Can sleep. Called serialized so that no
1568 * other events will occur in parallel. No further open will occur
1569 * until a close.
1570 */
1571
1572static int n_tty_open(struct tty_struct *tty)
1573{
1574 if (!tty)
1575 return -EINVAL;
1576
1577 /* These are ugly. Currently a malloc failure here can panic */
1578 if (!tty->read_buf) {
1579 tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1580 if (!tty->read_buf)
1581 return -ENOMEM;
1582 }
1583 if (!tty->echo_buf) {
1584 tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1585
1586 if (!tty->echo_buf)
1587 return -ENOMEM;
1588 }
1589 reset_buffer_flags(tty);
1590 tty->column = 0;
1591 n_tty_set_termios(tty, NULL);
1592 tty->minimum_to_wake = 1;
1593 tty->closing = 0;
1594 return 0;
1595}
1596
1597static inline int input_available_p(struct tty_struct *tty, int amt)
1598{
1599 tty_flush_to_ldisc(tty);
1600 if (tty->icanon && !L_EXTPROC(tty)) {
1601 if (tty->canon_data)
1602 return 1;
1603 } else if (tty->read_cnt >= (amt ? amt : 1))
1604 return 1;
1605
1606 return 0;
1607}
1608
1609/**
1610 * copy_from_read_buf - copy read data directly
1611 * @tty: terminal device
1612 * @b: user data
1613 * @nr: size of data
1614 *
1615 * Helper function to speed up n_tty_read. It is only called when
1616 * ICANON is off; it copies characters straight from the tty queue to
1617 * user space directly. It can be profitably called twice; once to
1618 * drain the space from the tail pointer to the (physical) end of the
1619 * buffer, and once to drain the space from the (physical) beginning of
1620 * the buffer to head pointer.
1621 *
1622 * Called under the tty->atomic_read_lock sem
1623 *
1624 */
1625
1626static int copy_from_read_buf(struct tty_struct *tty,
1627 unsigned char __user **b,
1628 size_t *nr)
1629
1630{
1631 int retval;
1632 size_t n;
1633 unsigned long flags;
1634
1635 retval = 0;
1636 spin_lock_irqsave(&tty->read_lock, flags);
1637 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1638 n = min(*nr, n);
1639 spin_unlock_irqrestore(&tty->read_lock, flags);
1640 if (n) {
1641 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1642 n -= retval;
1643 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1644 spin_lock_irqsave(&tty->read_lock, flags);
1645 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1646 tty->read_cnt -= n;
1647 /* Turn single EOF into zero-length read */
1648 if (L_EXTPROC(tty) && tty->icanon && n == 1) {
1649 if (!tty->read_cnt && (*b)[n-1] == EOF_CHAR(tty))
1650 n--;
1651 }
1652 spin_unlock_irqrestore(&tty->read_lock, flags);
1653 *b += n;
1654 *nr -= n;
1655 }
1656 return retval;
1657}
1658
1659extern ssize_t redirected_tty_write(struct file *, const char __user *,
1660 size_t, loff_t *);
1661
1662/**
1663 * job_control - check job control
1664 * @tty: tty
1665 * @file: file handle
1666 *
1667 * Perform job control management checks on this file/tty descriptor
1668 * and if appropriate send any needed signals and return a negative
1669 * error code if action should be taken.
1670 *
1671 * FIXME:
1672 * Locking: None - redirected write test is safe, testing
1673 * current->signal should possibly lock current->sighand
1674 * pgrp locking ?
1675 */
1676
1677static int job_control(struct tty_struct *tty, struct file *file)
1678{
1679 /* Job control check -- must be done at start and after
1680 every sleep (POSIX.1 7.1.1.4). */
1681 /* NOTE: not yet done after every sleep pending a thorough
1682 check of the logic of this change. -- jlc */
1683 /* don't stop on /dev/console */
1684 if (file->f_op->write != redirected_tty_write &&
1685 current->signal->tty == tty) {
1686 if (!tty->pgrp)
1687 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1688 else if (task_pgrp(current) != tty->pgrp) {
1689 if (is_ignored(SIGTTIN) ||
1690 is_current_pgrp_orphaned())
1691 return -EIO;
1692 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1693 set_thread_flag(TIF_SIGPENDING);
1694 return -ERESTARTSYS;
1695 }
1696 }
1697 return 0;
1698}
1699
1700
1701/**
1702 * n_tty_read - read function for tty
1703 * @tty: tty device
1704 * @file: file object
1705 * @buf: userspace buffer pointer
1706 * @nr: size of I/O
1707 *
1708 * Perform reads for the line discipline. We are guaranteed that the
1709 * line discipline will not be closed under us but we may get multiple
1710 * parallel readers and must handle this ourselves. We may also get
1711 * a hangup. Always called in user context, may sleep.
1712 *
1713 * This code must be sure never to sleep through a hangup.
1714 */
1715
1716static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1717 unsigned char __user *buf, size_t nr)
1718{
1719 unsigned char __user *b = buf;
1720 DECLARE_WAITQUEUE(wait, current);
1721 int c;
1722 int minimum, time;
1723 ssize_t retval = 0;
1724 ssize_t size;
1725 long timeout;
1726 unsigned long flags;
1727 int packet;
1728
1729do_it_again:
1730
1731 BUG_ON(!tty->read_buf);
1732
1733 c = job_control(tty, file);
1734 if (c < 0)
1735 return c;
1736
1737 minimum = time = 0;
1738 timeout = MAX_SCHEDULE_TIMEOUT;
1739 if (!tty->icanon) {
1740 time = (HZ / 10) * TIME_CHAR(tty);
1741 minimum = MIN_CHAR(tty);
1742 if (minimum) {
1743 if (time)
1744 tty->minimum_to_wake = 1;
1745 else if (!waitqueue_active(&tty->read_wait) ||
1746 (tty->minimum_to_wake > minimum))
1747 tty->minimum_to_wake = minimum;
1748 } else {
1749 timeout = 0;
1750 if (time) {
1751 timeout = time;
1752 time = 0;
1753 }
1754 tty->minimum_to_wake = minimum = 1;
1755 }
1756 }
1757
1758 /*
1759 * Internal serialization of reads.
1760 */
1761 if (file->f_flags & O_NONBLOCK) {
1762 if (!mutex_trylock(&tty->atomic_read_lock))
1763 return -EAGAIN;
1764 } else {
1765 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1766 return -ERESTARTSYS;
1767 }
1768 packet = tty->packet;
1769
1770 add_wait_queue(&tty->read_wait, &wait);
1771 while (nr) {
1772 /* First test for status change. */
1773 if (packet && tty->link->ctrl_status) {
1774 unsigned char cs;
1775 if (b != buf)
1776 break;
1777 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1778 cs = tty->link->ctrl_status;
1779 tty->link->ctrl_status = 0;
1780 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1781 if (tty_put_user(tty, cs, b++)) {
1782 retval = -EFAULT;
1783 b--;
1784 break;
1785 }
1786 nr--;
1787 break;
1788 }
1789 /* This statement must be first before checking for input
1790 so that any interrupt will set the state back to
1791 TASK_RUNNING. */
1792 set_current_state(TASK_INTERRUPTIBLE);
1793
1794 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1795 ((minimum - (b - buf)) >= 1))
1796 tty->minimum_to_wake = (minimum - (b - buf));
1797
1798 if (!input_available_p(tty, 0)) {
1799 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1800 retval = -EIO;
1801 break;
1802 }
1803 if (tty_hung_up_p(file))
1804 break;
1805 if (!timeout)
1806 break;
1807 if (file->f_flags & O_NONBLOCK) {
1808 retval = -EAGAIN;
1809 break;
1810 }
1811 if (signal_pending(current)) {
1812 retval = -ERESTARTSYS;
1813 break;
1814 }
1815 /* FIXME: does n_tty_set_room need locking ? */
1816 n_tty_set_room(tty);
1817 timeout = schedule_timeout(timeout);
1818 BUG_ON(!tty->read_buf);
1819 continue;
1820 }
1821 __set_current_state(TASK_RUNNING);
1822
1823 /* Deal with packet mode. */
1824 if (packet && b == buf) {
1825 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1826 retval = -EFAULT;
1827 b--;
1828 break;
1829 }
1830 nr--;
1831 }
1832
1833 if (tty->icanon && !L_EXTPROC(tty)) {
1834 /* N.B. avoid overrun if nr == 0 */
1835 while (nr && tty->read_cnt) {
1836 int eol;
1837
1838 eol = test_and_clear_bit(tty->read_tail,
1839 tty->read_flags);
1840 c = tty->read_buf[tty->read_tail];
1841 spin_lock_irqsave(&tty->read_lock, flags);
1842 tty->read_tail = ((tty->read_tail+1) &
1843 (N_TTY_BUF_SIZE-1));
1844 tty->read_cnt--;
1845 if (eol) {
1846 /* this test should be redundant:
1847 * we shouldn't be reading data if
1848 * canon_data is 0
1849 */
1850 if (--tty->canon_data < 0)
1851 tty->canon_data = 0;
1852 }
1853 spin_unlock_irqrestore(&tty->read_lock, flags);
1854
1855 if (!eol || (c != __DISABLED_CHAR)) {
1856 if (tty_put_user(tty, c, b++)) {
1857 retval = -EFAULT;
1858 b--;
1859 break;
1860 }
1861 nr--;
1862 }
1863 if (eol) {
1864 tty_audit_push(tty);
1865 break;
1866 }
1867 }
1868 if (retval)
1869 break;
1870 } else {
1871 int uncopied;
1872 /* The copy function takes the read lock and handles
1873 locking internally for this case */
1874 uncopied = copy_from_read_buf(tty, &b, &nr);
1875 uncopied += copy_from_read_buf(tty, &b, &nr);
1876 if (uncopied) {
1877 retval = -EFAULT;
1878 break;
1879 }
1880 }
1881
1882 /* If there is enough space in the read buffer now, let the
1883 * low-level driver know. We use n_tty_chars_in_buffer() to
1884 * check the buffer, as it now knows about canonical mode.
1885 * Otherwise, if the driver is throttled and the line is
1886 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1887 * we won't get any more characters.
1888 */
1889 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1890 n_tty_set_room(tty);
1891 check_unthrottle(tty);
1892 }
1893
1894 if (b - buf >= minimum)
1895 break;
1896 if (time)
1897 timeout = time;
1898 }
1899 mutex_unlock(&tty->atomic_read_lock);
1900 remove_wait_queue(&tty->read_wait, &wait);
1901
1902 if (!waitqueue_active(&tty->read_wait))
1903 tty->minimum_to_wake = minimum;
1904
1905 __set_current_state(TASK_RUNNING);
1906 size = b - buf;
1907 if (size) {
1908 retval = size;
1909 if (nr)
1910 clear_bit(TTY_PUSH, &tty->flags);
1911 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1912 goto do_it_again;
1913
1914 n_tty_set_room(tty);
1915 return retval;
1916}
1917
1918/**
1919 * n_tty_write - write function for tty
1920 * @tty: tty device
1921 * @file: file object
1922 * @buf: userspace buffer pointer
1923 * @nr: size of I/O
1924 *
1925 * Write function of the terminal device. This is serialized with
1926 * respect to other write callers but not to termios changes, reads
1927 * and other such events. Since the receive code will echo characters,
1928 * thus calling driver write methods, the output_lock is used in
1929 * the output processing functions called here as well as in the
1930 * echo processing function to protect the column state and space
1931 * left in the buffer.
1932 *
1933 * This code must be sure never to sleep through a hangup.
1934 *
1935 * Locking: output_lock to protect column state and space left
1936 * (note that the process_output*() functions take this
1937 * lock themselves)
1938 */
1939
1940static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1941 const unsigned char *buf, size_t nr)
1942{
1943 const unsigned char *b = buf;
1944 DECLARE_WAITQUEUE(wait, current);
1945 int c;
1946 ssize_t retval = 0;
1947
1948 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1949 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1950 retval = tty_check_change(tty);
1951 if (retval)
1952 return retval;
1953 }
1954
1955 /* Write out any echoed characters that are still pending */
1956 process_echoes(tty);
1957
1958 add_wait_queue(&tty->write_wait, &wait);
1959 while (1) {
1960 set_current_state(TASK_INTERRUPTIBLE);
1961 if (signal_pending(current)) {
1962 retval = -ERESTARTSYS;
1963 break;
1964 }
1965 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1966 retval = -EIO;
1967 break;
1968 }
1969 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1970 while (nr > 0) {
1971 ssize_t num = process_output_block(tty, b, nr);
1972 if (num < 0) {
1973 if (num == -EAGAIN)
1974 break;
1975 retval = num;
1976 goto break_out;
1977 }
1978 b += num;
1979 nr -= num;
1980 if (nr == 0)
1981 break;
1982 c = *b;
1983 if (process_output(c, tty) < 0)
1984 break;
1985 b++; nr--;
1986 }
1987 if (tty->ops->flush_chars)
1988 tty->ops->flush_chars(tty);
1989 } else {
1990 while (nr > 0) {
1991 c = tty->ops->write(tty, b, nr);
1992 if (c < 0) {
1993 retval = c;
1994 goto break_out;
1995 }
1996 if (!c)
1997 break;
1998 b += c;
1999 nr -= c;
2000 }
2001 }
2002 if (!nr)
2003 break;
2004 if (file->f_flags & O_NONBLOCK) {
2005 retval = -EAGAIN;
2006 break;
2007 }
2008 schedule();
2009 }
2010break_out:
2011 __set_current_state(TASK_RUNNING);
2012 remove_wait_queue(&tty->write_wait, &wait);
2013 if (b - buf != nr && tty->fasync)
2014 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2015 return (b - buf) ? b - buf : retval;
2016}
2017
2018/**
2019 * n_tty_poll - poll method for N_TTY
2020 * @tty: terminal device
2021 * @file: file accessing it
2022 * @wait: poll table
2023 *
2024 * Called when the line discipline is asked to poll() for data or
2025 * for special events. This code is not serialized with respect to
2026 * other events save open/close.
2027 *
2028 * This code must be sure never to sleep through a hangup.
2029 * Called without the kernel lock held - fine
2030 */
2031
2032static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2033 poll_table *wait)
2034{
2035 unsigned int mask = 0;
2036
2037 poll_wait(file, &tty->read_wait, wait);
2038 poll_wait(file, &tty->write_wait, wait);
2039 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2040 mask |= POLLIN | POLLRDNORM;
2041 if (tty->packet && tty->link->ctrl_status)
2042 mask |= POLLPRI | POLLIN | POLLRDNORM;
2043 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2044 mask |= POLLHUP;
2045 if (tty_hung_up_p(file))
2046 mask |= POLLHUP;
2047 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2048 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2049 tty->minimum_to_wake = MIN_CHAR(tty);
2050 else
2051 tty->minimum_to_wake = 1;
2052 }
2053 if (tty->ops->write && !tty_is_writelocked(tty) &&
2054 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2055 tty_write_room(tty) > 0)
2056 mask |= POLLOUT | POLLWRNORM;
2057 return mask;
2058}
2059
2060static unsigned long inq_canon(struct tty_struct *tty)
2061{
2062 int nr, head, tail;
2063
2064 if (!tty->canon_data)
2065 return 0;
2066 head = tty->canon_head;
2067 tail = tty->read_tail;
2068 nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2069 /* Skip EOF-chars.. */
2070 while (head != tail) {
2071 if (test_bit(tail, tty->read_flags) &&
2072 tty->read_buf[tail] == __DISABLED_CHAR)
2073 nr--;
2074 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2075 }
2076 return nr;
2077}
2078
2079static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2080 unsigned int cmd, unsigned long arg)
2081{
2082 int retval;
2083
2084 switch (cmd) {
2085 case TIOCOUTQ:
2086 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2087 case TIOCINQ:
2088 /* FIXME: Locking */
2089 retval = tty->read_cnt;
2090 if (L_ICANON(tty))
2091 retval = inq_canon(tty);
2092 return put_user(retval, (unsigned int __user *) arg);
2093 default:
2094 return n_tty_ioctl_helper(tty, file, cmd, arg);
2095 }
2096}
2097
2098struct tty_ldisc_ops tty_ldisc_N_TTY = {
2099 .magic = TTY_LDISC_MAGIC,
2100 .name = "n_tty",
2101 .open = n_tty_open,
2102 .close = n_tty_close,
2103 .flush_buffer = n_tty_flush_buffer,
2104 .chars_in_buffer = n_tty_chars_in_buffer,
2105 .read = n_tty_read,
2106 .write = n_tty_write,
2107 .ioctl = n_tty_ioctl,
2108 .set_termios = n_tty_set_termios,
2109 .poll = n_tty_poll,
2110 .receive_buf = n_tty_receive_buf,
2111 .write_wakeup = n_tty_write_wakeup
2112};
2113
2114/**
2115 * n_tty_inherit_ops - inherit N_TTY methods
2116 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2117 *
2118 * Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
2119 * methods.
2120 */
2121
2122void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2123{
2124 *ops = tty_ldisc_N_TTY;
2125 ops->owner = NULL;
2126 ops->refcount = ops->flags = 0;
2127}
2128EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
generated by cgit v1.2.2 (git 2.25.0) at 2025-04-25 23:31:09 -0400