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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}
189
190/**
191 * n_tty_flush_buffer - clean input queue
192 * @tty: terminal device
193 *
194 * Flush the input buffer. Called when the line discipline is
195 * being closed, when the tty layer wants the buffer flushed (eg
196 * at hangup) or when the N_TTY line discipline internally has to
197 * clean the pending queue (for example some signals).
198 *
199 * Locking: ctrl_lock, read_lock.
200 */
201
202static void n_tty_flush_buffer(struct tty_struct *tty)
203{
204 unsigned long flags;
205 /* clear everything and unthrottle the driver */
206 reset_buffer_flags(tty);
207
208 if (!tty->link)
209 return;
210
211 spin_lock_irqsave(&tty->ctrl_lock, flags);
212 if (tty->link->packet) {
213 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
214 wake_up_interruptible(&tty->link->read_wait);
215 }
216 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
217}
218
219/**
220 * n_tty_chars_in_buffer - report available bytes
221 * @tty: tty device
222 *
223 * Report the number of characters buffered to be delivered to user
224 * at this instant in time.
225 *
226 * Locking: read_lock
227 */
228
229static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
230{
231 unsigned long flags;
232 ssize_t n = 0;
233
234 spin_lock_irqsave(&tty->read_lock, flags);
235 if (!tty->icanon) {
236 n = tty->read_cnt;
237 } else if (tty->canon_data) {
238 n = (tty->canon_head > tty->read_tail) ?
239 tty->canon_head - tty->read_tail :
240 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
241 }
242 spin_unlock_irqrestore(&tty->read_lock, flags);
243 return n;
244}
245
246/**
247 * is_utf8_continuation - utf8 multibyte check
248 * @c: byte to check
249 *
250 * Returns true if the utf8 character 'c' is a multibyte continuation
251 * character. We use this to correctly compute the on screen size
252 * of the character when printing
253 */
254
255static inline int is_utf8_continuation(unsigned char c)
256{
257 return (c & 0xc0) == 0x80;
258}
259
260/**
261 * is_continuation - multibyte check
262 * @c: byte to check
263 *
264 * Returns true if the utf8 character 'c' is a multibyte continuation
265 * character and the terminal is in unicode mode.
266 */
267
268static inline int is_continuation(unsigned char c, struct tty_struct *tty)
269{
270 return I_IUTF8(tty) && is_utf8_continuation(c);
271}
272
273/**
274 * do_output_char - output one character
275 * @c: character (or partial unicode symbol)
276 * @tty: terminal device
277 * @space: space available in tty driver write buffer
278 *
279 * This is a helper function that handles one output character
280 * (including special characters like TAB, CR, LF, etc.),
281 * doing OPOST processing and putting the results in the
282 * tty driver's write buffer.
283 *
284 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
285 * and NLDLY. They simply aren't relevant in the world today.
286 * If you ever need them, add them here.
287 *
288 * Returns the number of bytes of buffer space used or -1 if
289 * no space left.
290 *
291 * Locking: should be called under the output_lock to protect
292 * the column state and space left in the buffer
293 */
294
295static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
296{
297 int spaces;
298
299 if (!space)
300 return -1;
301
302 switch (c) {
303 case '\n':
304 if (O_ONLRET(tty))
305 tty->column = 0;
306 if (O_ONLCR(tty)) {
307 if (space < 2)
308 return -1;
309 tty->canon_column = tty->column = 0;
310 tty->ops->write(tty, "\r\n", 2);
311 return 2;
312 }
313 tty->canon_column = tty->column;
314 break;
315 case '\r':
316 if (O_ONOCR(tty) && tty->column == 0)
317 return 0;
318 if (O_OCRNL(tty)) {
319 c = '\n';
320 if (O_ONLRET(tty))
321 tty->canon_column = tty->column = 0;
322 break;
323 }
324 tty->canon_column = tty->column = 0;
325 break;
326 case '\t':
327 spaces = 8 - (tty->column & 7);
328 if (O_TABDLY(tty) == XTABS) {
329 if (space < spaces)
330 return -1;
331 tty->column += spaces;
332 tty->ops->write(tty, " ", spaces);
333 return spaces;
334 }
335 tty->column += spaces;
336 break;
337 case '\b':
338 if (tty->column > 0)
339 tty->column--;
340 break;
341 default:
342 if (!iscntrl(c)) {
343 if (O_OLCUC(tty))
344 c = toupper(c);
345 if (!is_continuation(c, tty))
346 tty->column++;
347 }
348 break;
349 }
350
351 tty_put_char(tty, c);
352 return 1;
353}
354
355/**
356 * process_output - output post processor
357 * @c: character (or partial unicode symbol)
358 * @tty: terminal device
359 *
360 * Output one character with OPOST processing.
361 * Returns -1 when the output device is full and the character
362 * must be retried.
363 *
364 * Locking: output_lock to protect column state and space left
365 * (also, this is called from n_tty_write under the
366 * tty layer write lock)
367 */
368
369static int process_output(unsigned char c, struct tty_struct *tty)
370{
371 int space, retval;
372
373 mutex_lock(&tty->output_lock);
374
375 space = tty_write_room(tty);
376 retval = do_output_char(c, tty, space);
377
378 mutex_unlock(&tty->output_lock);
379 if (retval < 0)
380 return -1;
381 else
382 return 0;
383}
384
385/**
386 * process_output_block - block post processor
387 * @tty: terminal device
388 * @buf: character buffer
389 * @nr: number of bytes to output
390 *
391 * Output a block of characters with OPOST processing.
392 * Returns the number of characters output.
393 *
394 * This path is used to speed up block console writes, among other
395 * things when processing blocks of output data. It handles only
396 * the simple cases normally found and helps to generate blocks of
397 * symbols for the console driver and thus improve performance.
398 *
399 * Locking: output_lock to protect column state and space left
400 * (also, this is called from n_tty_write under the
401 * tty layer write lock)
402 */
403
404static ssize_t process_output_block(struct tty_struct *tty,
405 const unsigned char *buf, unsigned int nr)
406{
407 int space;
408 int i;
409 const unsigned char *cp;
410
411 mutex_lock(&tty->output_lock);
412
413 space = tty_write_room(tty);
414 if (!space) {
415 mutex_unlock(&tty->output_lock);
416 return 0;
417 }
418 if (nr > space)
419 nr = space;
420
421 for (i = 0, cp = buf; i < nr; i++, cp++) {
422 unsigned char c = *cp;
423
424 switch (c) {
425 case '\n':
426 if (O_ONLRET(tty))
427 tty->column = 0;
428 if (O_ONLCR(tty))
429 goto break_out;
430 tty->canon_column = tty->column;
431 break;
432 case '\r':
433 if (O_ONOCR(tty) && tty->column == 0)
434 goto break_out;
435 if (O_OCRNL(tty))
436 goto break_out;
437 tty->canon_column = tty->column = 0;
438 break;
439 case '\t':
440 goto break_out;
441 case '\b':
442 if (tty->column > 0)
443 tty->column--;
444 break;
445 default:
446 if (!iscntrl(c)) {
447 if (O_OLCUC(tty))
448 goto break_out;
449 if (!is_continuation(c, tty))
450 tty->column++;
451 }
452 break;
453 }
454 }
455break_out:
456 i = tty->ops->write(tty, buf, i);
457
458 mutex_unlock(&tty->output_lock);
459 return i;
460}
461
462/**
463 * process_echoes - write pending echo characters
464 * @tty: terminal device
465 *
466 * Write previously buffered echo (and other ldisc-generated)
467 * characters to the tty.
468 *
469 * Characters generated by the ldisc (including echoes) need to
470 * be buffered because the driver's write buffer can fill during
471 * heavy program output. Echoing straight to the driver will
472 * often fail under these conditions, causing lost characters and
473 * resulting mismatches of ldisc state information.
474 *
475 * Since the ldisc state must represent the characters actually sent
476 * to the driver at the time of the write, operations like certain
477 * changes in column state are also saved in the buffer and executed
478 * here.
479 *
480 * A circular fifo buffer is used so that the most recent characters
481 * are prioritized. Also, when control characters are echoed with a
482 * prefixed "^", the pair is treated atomically and thus not separated.
483 *
484 * Locking: output_lock to protect column state and space left,
485 * echo_lock to protect the echo buffer
486 */
487
488static void process_echoes(struct tty_struct *tty)
489{
490 int space, nr;
491 unsigned char c;
492 unsigned char *cp, *buf_end;
493
494 if (!tty->echo_cnt)
495 return;
496
497 mutex_lock(&tty->output_lock);
498 mutex_lock(&tty->echo_lock);
499
500 space = tty_write_room(tty);
501
502 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
503 cp = tty->echo_buf + tty->echo_pos;
504 nr = tty->echo_cnt;
505 while (nr > 0) {
506 c = *cp;
507 if (c == ECHO_OP_START) {
508 unsigned char op;
509 unsigned char *opp;
510 int no_space_left = 0;
511
512 /*
513 * If the buffer byte is the start of a multi-byte
514 * operation, get the next byte, which is either the
515 * op code or a control character value.
516 */
517 opp = cp + 1;
518 if (opp == buf_end)
519 opp -= N_TTY_BUF_SIZE;
520 op = *opp;
521
522 switch (op) {
523 unsigned int num_chars, num_bs;
524
525 case ECHO_OP_ERASE_TAB:
526 if (++opp == buf_end)
527 opp -= N_TTY_BUF_SIZE;
528 num_chars = *opp;
529
530 /*
531 * Determine how many columns to go back
532 * in order to erase the tab.
533 * This depends on the number of columns
534 * used by other characters within the tab
535 * area. If this (modulo 8) count is from
536 * the start of input rather than from a
537 * previous tab, we offset by canon column.
538 * Otherwise, tab spacing is normal.
539 */
540 if (!(num_chars & 0x80))
541 num_chars += tty->canon_column;
542 num_bs = 8 - (num_chars & 7);
543
544 if (num_bs > space) {
545 no_space_left = 1;
546 break;
547 }
548 space -= num_bs;
549 while (num_bs--) {
550 tty_put_char(tty, '\b');
551 if (tty->column > 0)
552 tty->column--;
553 }
554 cp += 3;
555 nr -= 3;
556 break;
557
558 case ECHO_OP_SET_CANON_COL:
559 tty->canon_column = tty->column;
560 cp += 2;
561 nr -= 2;
562 break;
563
564 case ECHO_OP_MOVE_BACK_COL:
565 if (tty->column > 0)
566 tty->column--;
567 cp += 2;
568 nr -= 2;
569 break;
570
571 case ECHO_OP_START:
572 /* This is an escaped echo op start code */
573 if (!space) {
574 no_space_left = 1;
575 break;
576 }
577 tty_put_char(tty, ECHO_OP_START);
578 tty->column++;
579 space--;
580 cp += 2;
581 nr -= 2;
582 break;
583
584 default:
585 /*
586 * If the op is not a special byte code,
587 * it is a ctrl char tagged to be echoed
588 * as "^X" (where X is the letter
589 * representing the control char).
590 * Note that we must ensure there is
591 * enough space for the whole ctrl pair.
592 *
593 */
594 if (space < 2) {
595 no_space_left = 1;
596 break;
597 }
598 tty_put_char(tty, '^');
599 tty_put_char(tty, op ^ 0100);
600 tty->column += 2;
601 space -= 2;
602 cp += 2;
603 nr -= 2;
604 }
605
606 if (no_space_left)
607 break;
608 } else {
609 if (O_OPOST(tty) &&
610 !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
611 int retval = do_output_char(c, tty, space);
612 if (retval < 0)
613 break;
614 space -= retval;
615 } else {
616 if (!space)
617 break;
618 tty_put_char(tty, c);
619 space -= 1;
620 }
621 cp += 1;
622 nr -= 1;
623 }
624
625 /* When end of circular buffer reached, wrap around */
626 if (cp >= buf_end)
627 cp -= N_TTY_BUF_SIZE;
628 }
629
630 if (nr == 0) {
631 tty->echo_pos = 0;
632 tty->echo_cnt = 0;
633 tty->echo_overrun = 0;
634 } else {
635 int num_processed = tty->echo_cnt - nr;
636 tty->echo_pos += num_processed;
637 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
638 tty->echo_cnt = nr;
639 if (num_processed > 0)
640 tty->echo_overrun = 0;
641 }
642
643 mutex_unlock(&tty->echo_lock);
644 mutex_unlock(&tty->output_lock);
645
646 if (tty->ops->flush_chars)
647 tty->ops->flush_chars(tty);
648}
649
650/**
651 * add_echo_byte - add a byte to the echo buffer
652 * @c: unicode byte to echo
653 * @tty: terminal device
654 *
655 * Add a character or operation byte to the echo buffer.
656 *
657 * Should be called under the echo lock to protect the echo buffer.
658 */
659
660static void add_echo_byte(unsigned char c, struct tty_struct *tty)
661{
662 int new_byte_pos;
663
664 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
665 /* Circular buffer is already at capacity */
666 new_byte_pos = tty->echo_pos;
667
668 /*
669 * Since the buffer start position needs to be advanced,
670 * be sure to step by a whole operation byte group.
671 */
672 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
673 if (tty->echo_buf[(tty->echo_pos + 1) &
674 (N_TTY_BUF_SIZE - 1)] ==
675 ECHO_OP_ERASE_TAB) {
676 tty->echo_pos += 3;
677 tty->echo_cnt -= 2;
678 } else {
679 tty->echo_pos += 2;
680 tty->echo_cnt -= 1;
681 }
682 } else {
683 tty->echo_pos++;
684 }
685 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
686
687 tty->echo_overrun = 1;
688 } else {
689 new_byte_pos = tty->echo_pos + tty->echo_cnt;
690 new_byte_pos &= N_TTY_BUF_SIZE - 1;
691 tty->echo_cnt++;
692 }
693
694 tty->echo_buf[new_byte_pos] = c;
695}
696
697/**
698 * echo_move_back_col - add operation to move back a column
699 * @tty: terminal device
700 *
701 * Add an operation to the echo buffer to move back one column.
702 *
703 * Locking: echo_lock to protect the echo buffer
704 */
705
706static void echo_move_back_col(struct tty_struct *tty)
707{
708 mutex_lock(&tty->echo_lock);
709
710 add_echo_byte(ECHO_OP_START, tty);
711 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
712
713 mutex_unlock(&tty->echo_lock);
714}
715
716/**
717 * echo_set_canon_col - add operation to set the canon column
718 * @tty: terminal device
719 *
720 * Add an operation to the echo buffer to set the canon column
721 * to the current column.
722 *
723 * Locking: echo_lock to protect the echo buffer
724 */
725
726static void echo_set_canon_col(struct tty_struct *tty)
727{
728 mutex_lock(&tty->echo_lock);
729
730 add_echo_byte(ECHO_OP_START, tty);
731 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
732
733 mutex_unlock(&tty->echo_lock);
734}
735
736/**
737 * echo_erase_tab - add operation to erase a tab
738 * @num_chars: number of character columns already used
739 * @after_tab: true if num_chars starts after a previous tab
740 * @tty: terminal device
741 *
742 * Add an operation to the echo buffer to erase a tab.
743 *
744 * Called by the eraser function, which knows how many character
745 * columns have been used since either a previous tab or the start
746 * of input. This information will be used later, along with
747 * canon column (if applicable), to go back the correct number
748 * of columns.
749 *
750 * Locking: echo_lock to protect the echo buffer
751 */
752
753static void echo_erase_tab(unsigned int num_chars, int after_tab,
754 struct tty_struct *tty)
755{
756 mutex_lock(&tty->echo_lock);
757
758 add_echo_byte(ECHO_OP_START, tty);
759 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
760
761 /* We only need to know this modulo 8 (tab spacing) */
762 num_chars &= 7;
763
764 /* Set the high bit as a flag if num_chars is after a previous tab */
765 if (after_tab)
766 num_chars |= 0x80;
767
768 add_echo_byte(num_chars, tty);
769
770 mutex_unlock(&tty->echo_lock);
771}
772
773/**
774 * echo_char_raw - echo a character raw
775 * @c: unicode byte to echo
776 * @tty: terminal device
777 *
778 * Echo user input back onto the screen. This must be called only when
779 * L_ECHO(tty) is true. Called from the driver receive_buf path.
780 *
781 * This variant does not treat control characters specially.
782 *
783 * Locking: echo_lock to protect the echo buffer
784 */
785
786static void echo_char_raw(unsigned char c, struct tty_struct *tty)
787{
788 mutex_lock(&tty->echo_lock);
789
790 if (c == ECHO_OP_START) {
791 add_echo_byte(ECHO_OP_START, tty);
792 add_echo_byte(ECHO_OP_START, tty);
793 } else {
794 add_echo_byte(c, tty);
795 }
796
797 mutex_unlock(&tty->echo_lock);
798}
799
800/**
801 * echo_char - echo a character
802 * @c: unicode byte to echo
803 * @tty: terminal device
804 *
805 * Echo user input back onto the screen. This must be called only when
806 * L_ECHO(tty) is true. Called from the driver receive_buf path.
807 *
808 * This variant tags control characters to be echoed as "^X"
809 * (where X is the letter representing the control char).
810 *
811 * Locking: echo_lock to protect the echo buffer
812 */
813
814static void echo_char(unsigned char c, struct tty_struct *tty)
815{
816 mutex_lock(&tty->echo_lock);
817
818 if (c == ECHO_OP_START) {
819 add_echo_byte(ECHO_OP_START, tty);
820 add_echo_byte(ECHO_OP_START, tty);
821 } else {
822 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
823 add_echo_byte(ECHO_OP_START, tty);
824 add_echo_byte(c, tty);
825 }
826
827 mutex_unlock(&tty->echo_lock);
828}
829
830/**
831 * finish_erasing - complete erase
832 * @tty: tty doing the erase
833 */
834
835static inline void finish_erasing(struct tty_struct *tty)
836{
837 if (tty->erasing) {
838 echo_char_raw('/', tty);
839 tty->erasing = 0;
840 }
841}
842
843/**
844 * eraser - handle erase function
845 * @c: character input
846 * @tty: terminal device
847 *
848 * Perform erase and necessary output when an erase character is
849 * present in the stream from the driver layer. Handles the complexities
850 * of UTF-8 multibyte symbols.
851 *
852 * Locking: read_lock for tty buffers
853 */
854
855static void eraser(unsigned char c, struct tty_struct *tty)
856{
857 enum { ERASE, WERASE, KILL } kill_type;
858 int head, seen_alnums, cnt;
859 unsigned long flags;
860
861 /* FIXME: locking needed ? */
862 if (tty->read_head == tty->canon_head) {
863 /* process_output('\a', tty); */ /* what do you think? */
864 return;
865 }
866 if (c == ERASE_CHAR(tty))
867 kill_type = ERASE;
868 else if (c == WERASE_CHAR(tty))
869 kill_type = WERASE;
870 else {
871 if (!L_ECHO(tty)) {
872 spin_lock_irqsave(&tty->read_lock, flags);
873 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
874 (N_TTY_BUF_SIZE - 1));
875 tty->read_head = tty->canon_head;
876 spin_unlock_irqrestore(&tty->read_lock, flags);
877 return;
878 }
879 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
880 spin_lock_irqsave(&tty->read_lock, flags);
881 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
882 (N_TTY_BUF_SIZE - 1));
883 tty->read_head = tty->canon_head;
884 spin_unlock_irqrestore(&tty->read_lock, flags);
885 finish_erasing(tty);
886 echo_char(KILL_CHAR(tty), tty);
887 /* Add a newline if ECHOK is on and ECHOKE is off. */
888 if (L_ECHOK(tty))
889 echo_char_raw('\n', tty);
890 return;
891 }
892 kill_type = KILL;
893 }
894
895 seen_alnums = 0;
896 /* FIXME: Locking ?? */
897 while (tty->read_head != tty->canon_head) {
898 head = tty->read_head;
899
900 /* erase a single possibly multibyte character */
901 do {
902 head = (head - 1) & (N_TTY_BUF_SIZE-1);
903 c = tty->read_buf[head];
904 } while (is_continuation(c, tty) && head != tty->canon_head);
905
906 /* do not partially erase */
907 if (is_continuation(c, tty))
908 break;
909
910 if (kill_type == WERASE) {
911 /* Equivalent to BSD's ALTWERASE. */
912 if (isalnum(c) || c == '_')
913 seen_alnums++;
914 else if (seen_alnums)
915 break;
916 }
917 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
918 spin_lock_irqsave(&tty->read_lock, flags);
919 tty->read_head = head;
920 tty->read_cnt -= cnt;
921 spin_unlock_irqrestore(&tty->read_lock, flags);
922 if (L_ECHO(tty)) {
923 if (L_ECHOPRT(tty)) {
924 if (!tty->erasing) {
925 echo_char_raw('\\', tty);
926 tty->erasing = 1;
927 }
928 /* if cnt > 1, output a multi-byte character */
929 echo_char(c, tty);
930 while (--cnt > 0) {
931 head = (head+1) & (N_TTY_BUF_SIZE-1);
932 echo_char_raw(tty->read_buf[head], tty);
933 echo_move_back_col(tty);
934 }
935 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
936 echo_char(ERASE_CHAR(tty), tty);
937 } else if (c == '\t') {
938 unsigned int num_chars = 0;
939 int after_tab = 0;
940 unsigned long tail = tty->read_head;
941
942 /*
943 * Count the columns used for characters
944 * since the start of input or after a
945 * previous tab.
946 * This info is used to go back the correct
947 * number of columns.
948 */
949 while (tail != tty->canon_head) {
950 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
951 c = tty->read_buf[tail];
952 if (c == '\t') {
953 after_tab = 1;
954 break;
955 } else if (iscntrl(c)) {
956 if (L_ECHOCTL(tty))
957 num_chars += 2;
958 } else if (!is_continuation(c, tty)) {
959 num_chars++;
960 }
961 }
962 echo_erase_tab(num_chars, after_tab, tty);
963 } else {
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 if (!iscntrl(c) || L_ECHOCTL(tty)) {
970 echo_char_raw('\b', tty);
971 echo_char_raw(' ', tty);
972 echo_char_raw('\b', tty);
973 }
974 }
975 }
976 if (kill_type == ERASE)
977 break;
978 }
979 if (tty->read_head == tty->canon_head && L_ECHO(tty))
980 finish_erasing(tty);
981}
982
983/**
984 * isig - handle the ISIG optio
985 * @sig: signal
986 * @tty: terminal
987 * @flush: force flush
988 *
989 * Called when a signal is being sent due to terminal input. This
990 * may caus terminal flushing to take place according to the termios
991 * settings and character used. Called from the driver receive_buf
992 * path so serialized.
993 *
994 * Locking: ctrl_lock, read_lock (both via flush buffer)
995 */
996
997static inline void isig(int sig, struct tty_struct *tty, int flush)
998{
999 if (tty->pgrp)
1000 kill_pgrp(tty->pgrp, sig, 1);
1001 if (flush || !L_NOFLSH(tty)) {
1002 n_tty_flush_buffer(tty);
1003 tty_driver_flush_buffer(tty);
1004 }
1005}
1006
1007/**
1008 * n_tty_receive_break - handle break
1009 * @tty: terminal
1010 *
1011 * An RS232 break event has been hit in the incoming bitstream. This
1012 * can cause a variety of events depending upon the termios settings.
1013 *
1014 * Called from the receive_buf path so single threaded.
1015 */
1016
1017static inline void n_tty_receive_break(struct tty_struct *tty)
1018{
1019 if (I_IGNBRK(tty))
1020 return;
1021 if (I_BRKINT(tty)) {
1022 isig(SIGINT, tty, 1);
1023 return;
1024 }
1025 if (I_PARMRK(tty)) {
1026 put_tty_queue('\377', tty);
1027 put_tty_queue('\0', tty);
1028 }
1029 put_tty_queue('\0', tty);
1030 wake_up_interruptible(&tty->read_wait);
1031}
1032
1033/**
1034 * n_tty_receive_overrun - handle overrun reporting
1035 * @tty: terminal
1036 *
1037 * Data arrived faster than we could process it. While the tty
1038 * driver has flagged this the bits that were missed are gone
1039 * forever.
1040 *
1041 * Called from the receive_buf path so single threaded. Does not
1042 * need locking as num_overrun and overrun_time are function
1043 * private.
1044 */
1045
1046static inline void n_tty_receive_overrun(struct tty_struct *tty)
1047{
1048 char buf[64];
1049
1050 tty->num_overrun++;
1051 if (time_before(tty->overrun_time, jiffies - HZ) ||
1052 time_after(tty->overrun_time, jiffies)) {
1053 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1054 tty_name(tty, buf),
1055 tty->num_overrun);
1056 tty->overrun_time = jiffies;
1057 tty->num_overrun = 0;
1058 }
1059}
1060
1061/**
1062 * n_tty_receive_parity_error - error notifier
1063 * @tty: terminal device
1064 * @c: character
1065 *
1066 * Process a parity error and queue the right data to indicate
1067 * the error case if necessary. Locking as per n_tty_receive_buf.
1068 */
1069static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1070 unsigned char c)
1071{
1072 if (I_IGNPAR(tty))
1073 return;
1074 if (I_PARMRK(tty)) {
1075 put_tty_queue('\377', tty);
1076 put_tty_queue('\0', tty);
1077 put_tty_queue(c, tty);
1078 } else if (I_INPCK(tty))
1079 put_tty_queue('\0', tty);
1080 else
1081 put_tty_queue(c, tty);
1082 wake_up_interruptible(&tty->read_wait);
1083}
1084
1085/**
1086 * n_tty_receive_char - perform processing
1087 * @tty: terminal device
1088 * @c: character
1089 *
1090 * Process an individual character of input received from the driver.
1091 * This is serialized with respect to itself by the rules for the
1092 * driver above.
1093 */
1094
1095static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1096{
1097 unsigned long flags;
1098 int parmrk;
1099
1100 if (tty->raw) {
1101 put_tty_queue(c, tty);
1102 return;
1103 }
1104
1105 if (I_ISTRIP(tty))
1106 c &= 0x7f;
1107 if (I_IUCLC(tty) && L_IEXTEN(tty))
1108 c = tolower(c);
1109
1110 if (L_EXTPROC(tty)) {
1111 put_tty_queue(c, tty);
1112 return;
1113 }
1114
1115 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1116 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1117 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1118 start_tty(tty);
1119 process_echoes(tty);
1120 }
1121
1122 if (tty->closing) {
1123 if (I_IXON(tty)) {
1124 if (c == START_CHAR(tty)) {
1125 start_tty(tty);
1126 process_echoes(tty);
1127 } else if (c == STOP_CHAR(tty))
1128 stop_tty(tty);
1129 }
1130 return;
1131 }
1132
1133 /*
1134 * If the previous character was LNEXT, or we know that this
1135 * character is not one of the characters that we'll have to
1136 * handle specially, do shortcut processing to speed things
1137 * up.
1138 */
1139 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1140 tty->lnext = 0;
1141 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1142 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1143 /* beep if no space */
1144 if (L_ECHO(tty))
1145 process_output('\a', tty);
1146 return;
1147 }
1148 if (L_ECHO(tty)) {
1149 finish_erasing(tty);
1150 /* Record the column of first canon char. */
1151 if (tty->canon_head == tty->read_head)
1152 echo_set_canon_col(tty);
1153 echo_char(c, tty);
1154 process_echoes(tty);
1155 }
1156 if (parmrk)
1157 put_tty_queue(c, tty);
1158 put_tty_queue(c, tty);
1159 return;
1160 }
1161
1162 if (I_IXON(tty)) {
1163 if (c == START_CHAR(tty)) {
1164 start_tty(tty);
1165 process_echoes(tty);
1166 return;
1167 }
1168 if (c == STOP_CHAR(tty)) {
1169 stop_tty(tty);
1170 return;
1171 }
1172 }
1173
1174 if (L_ISIG(tty)) {
1175 int signal;
1176 signal = SIGINT;
1177 if (c == INTR_CHAR(tty))
1178 goto send_signal;
1179 signal = SIGQUIT;
1180 if (c == QUIT_CHAR(tty))
1181 goto send_signal;
1182 signal = SIGTSTP;
1183 if (c == SUSP_CHAR(tty)) {
1184send_signal:
1185 /*
1186 * Note that we do not use isig() here because we want
1187 * the order to be:
1188 * 1) flush, 2) echo, 3) signal
1189 */
1190 if (!L_NOFLSH(tty)) {
1191 n_tty_flush_buffer(tty);
1192 tty_driver_flush_buffer(tty);
1193 }
1194 if (I_IXON(tty))
1195 start_tty(tty);
1196 if (L_ECHO(tty)) {
1197 echo_char(c, tty);
1198 process_echoes(tty);
1199 }
1200 if (tty->pgrp)
1201 kill_pgrp(tty->pgrp, signal, 1);
1202 return;
1203 }
1204 }
1205
1206 if (c == '\r') {
1207 if (I_IGNCR(tty))
1208 return;
1209 if (I_ICRNL(tty))
1210 c = '\n';
1211 } else if (c == '\n' && I_INLCR(tty))
1212 c = '\r';
1213
1214 if (tty->icanon) {
1215 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1216 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1217 eraser(c, tty);
1218 process_echoes(tty);
1219 return;
1220 }
1221 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1222 tty->lnext = 1;
1223 if (L_ECHO(tty)) {
1224 finish_erasing(tty);
1225 if (L_ECHOCTL(tty)) {
1226 echo_char_raw('^', tty);
1227 echo_char_raw('\b', tty);
1228 process_echoes(tty);
1229 }
1230 }
1231 return;
1232 }
1233 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1234 L_IEXTEN(tty)) {
1235 unsigned long tail = tty->canon_head;
1236
1237 finish_erasing(tty);
1238 echo_char(c, tty);
1239 echo_char_raw('\n', tty);
1240 while (tail != tty->read_head) {
1241 echo_char(tty->read_buf[tail], tty);
1242 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1243 }
1244 process_echoes(tty);
1245 return;
1246 }
1247 if (c == '\n') {
1248 if (tty->read_cnt >= N_TTY_BUF_SIZE) {
1249 if (L_ECHO(tty))
1250 process_output('\a', tty);
1251 return;
1252 }
1253 if (L_ECHO(tty) || L_ECHONL(tty)) {
1254 echo_char_raw('\n', tty);
1255 process_echoes(tty);
1256 }
1257 goto handle_newline;
1258 }
1259 if (c == EOF_CHAR(tty)) {
1260 if (tty->read_cnt >= N_TTY_BUF_SIZE)
1261 return;
1262 if (tty->canon_head != tty->read_head)
1263 set_bit(TTY_PUSH, &tty->flags);
1264 c = __DISABLED_CHAR;
1265 goto handle_newline;
1266 }
1267 if ((c == EOL_CHAR(tty)) ||
1268 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1269 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1270 ? 1 : 0;
1271 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
1272 if (L_ECHO(tty))
1273 process_output('\a', tty);
1274 return;
1275 }
1276 /*
1277 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1278 */
1279 if (L_ECHO(tty)) {
1280 /* Record the column of first canon char. */
1281 if (tty->canon_head == tty->read_head)
1282 echo_set_canon_col(tty);
1283 echo_char(c, tty);
1284 process_echoes(tty);
1285 }
1286 /*
1287 * XXX does PARMRK doubling happen for
1288 * EOL_CHAR and EOL2_CHAR?
1289 */
1290 if (parmrk)
1291 put_tty_queue(c, tty);
1292
1293handle_newline:
1294 spin_lock_irqsave(&tty->read_lock, flags);
1295 set_bit(tty->read_head, tty->read_flags);
1296 put_tty_queue_nolock(c, tty);
1297 tty->canon_head = tty->read_head;
1298 tty->canon_data++;
1299 spin_unlock_irqrestore(&tty->read_lock, flags);
1300 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1301 if (waitqueue_active(&tty->read_wait))
1302 wake_up_interruptible(&tty->read_wait);
1303 return;
1304 }
1305 }
1306
1307 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1308 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1309 /* beep if no space */
1310 if (L_ECHO(tty))
1311 process_output('\a', tty);
1312 return;
1313 }
1314 if (L_ECHO(tty)) {
1315 finish_erasing(tty);
1316 if (c == '\n')
1317 echo_char_raw('\n', tty);
1318 else {
1319 /* Record the column of first canon char. */
1320 if (tty->canon_head == tty->read_head)
1321 echo_set_canon_col(tty);
1322 echo_char(c, tty);
1323 }
1324 process_echoes(tty);
1325 }
1326
1327 if (parmrk)
1328 put_tty_queue(c, tty);
1329
1330 put_tty_queue(c, tty);
1331}
1332
1333
1334/**
1335 * n_tty_write_wakeup - asynchronous I/O notifier
1336 * @tty: tty device
1337 *
1338 * Required for the ptys, serial driver etc. since processes
1339 * that attach themselves to the master and rely on ASYNC
1340 * IO must be woken up
1341 */
1342
1343static void n_tty_write_wakeup(struct tty_struct *tty)
1344{
1345 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
1346 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1347}
1348
1349/**
1350 * n_tty_receive_buf - data receive
1351 * @tty: terminal device
1352 * @cp: buffer
1353 * @fp: flag buffer
1354 * @count: characters
1355 *
1356 * Called by the terminal driver when a block of characters has
1357 * been received. This function must be called from soft contexts
1358 * not from interrupt context. The driver is responsible for making
1359 * calls one at a time and in order (or using flush_to_ldisc)
1360 */
1361
1362static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1363 char *fp, int count)
1364{
1365 const unsigned char *p;
1366 char *f, flags = TTY_NORMAL;
1367 int i;
1368 char buf[64];
1369 unsigned long cpuflags;
1370
1371 if (!tty->read_buf)
1372 return;
1373
1374 if (tty->real_raw) {
1375 spin_lock_irqsave(&tty->read_lock, cpuflags);
1376 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1377 N_TTY_BUF_SIZE - tty->read_head);
1378 i = min(count, i);
1379 memcpy(tty->read_buf + tty->read_head, cp, i);
1380 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1381 tty->read_cnt += i;
1382 cp += i;
1383 count -= i;
1384
1385 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1386 N_TTY_BUF_SIZE - tty->read_head);
1387 i = min(count, i);
1388 memcpy(tty->read_buf + tty->read_head, cp, i);
1389 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1390 tty->read_cnt += i;
1391 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1392 } else {
1393 for (i = count, p = cp, f = fp; i; i--, p++) {
1394 if (f)
1395 flags = *f++;
1396 switch (flags) {
1397 case TTY_NORMAL:
1398 n_tty_receive_char(tty, *p);
1399 break;
1400 case TTY_BREAK:
1401 n_tty_receive_break(tty);
1402 break;
1403 case TTY_PARITY:
1404 case TTY_FRAME:
1405 n_tty_receive_parity_error(tty, *p);
1406 break;
1407 case TTY_OVERRUN:
1408 n_tty_receive_overrun(tty);
1409 break;
1410 default:
1411 printk(KERN_ERR "%s: unknown flag %d\n",
1412 tty_name(tty, buf), flags);
1413 break;
1414 }
1415 }
1416 if (tty->ops->flush_chars)
1417 tty->ops->flush_chars(tty);
1418 }
1419
1420 n_tty_set_room(tty);
1421
1422 if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
1423 L_EXTPROC(tty)) {
1424 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1425 if (waitqueue_active(&tty->read_wait))
1426 wake_up_interruptible(&tty->read_wait);
1427 }
1428
1429 /*
1430 * Check the remaining room for the input canonicalization
1431 * mode. We don't want to throttle the driver if we're in
1432 * canonical mode and don't have a newline yet!
1433 */
1434 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1435 tty_throttle(tty);
1436}
1437
1438int is_ignored(int sig)
1439{
1440 return (sigismember(¤t->blocked, sig) ||
1441 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1442}
1443
1444/**
1445 * n_tty_set_termios - termios data changed
1446 * @tty: terminal
1447 * @old: previous data
1448 *
1449 * Called by the tty layer when the user changes termios flags so
1450 * that the line discipline can plan ahead. This function cannot sleep
1451 * and is protected from re-entry by the tty layer. The user is
1452 * guaranteed that this function will not be re-entered or in progress
1453 * when the ldisc is closed.
1454 *
1455 * Locking: Caller holds tty->termios_mutex
1456 */
1457
1458static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1459{
1460 int canon_change = 1;
1461 BUG_ON(!tty);
1462
1463 if (old)
1464 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1465 if (canon_change) {
1466 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1467 tty->canon_head = tty->read_tail;
1468 tty->canon_data = 0;
1469 tty->erasing = 0;
1470 }
1471
1472 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1473 wake_up_interruptible(&tty->read_wait);
1474
1475 tty->icanon = (L_ICANON(tty) != 0);
1476 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1477 tty->raw = 1;
1478 tty->real_raw = 1;
1479 n_tty_set_room(tty);
1480 return;
1481 }
1482 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1483 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1484 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1485 I_PARMRK(tty)) {
1486 memset(tty->process_char_map, 0, 256/8);
1487
1488 if (I_IGNCR(tty) || I_ICRNL(tty))
1489 set_bit('\r', tty->process_char_map);
1490 if (I_INLCR(tty))
1491 set_bit('\n', tty->process_char_map);
1492
1493 if (L_ICANON(tty)) {
1494 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1495 set_bit(KILL_CHAR(tty), tty->process_char_map);
1496 set_bit(EOF_CHAR(tty), tty->process_char_map);
1497 set_bit('\n', tty->process_char_map);
1498 set_bit(EOL_CHAR(tty), tty->process_char_map);
1499 if (L_IEXTEN(tty)) {
1500 set_bit(WERASE_CHAR(tty),
1501 tty->process_char_map);
1502 set_bit(LNEXT_CHAR(tty),
1503 tty->process_char_map);
1504 set_bit(EOL2_CHAR(tty),
1505 tty->process_char_map);
1506 if (L_ECHO(tty))
1507 set_bit(REPRINT_CHAR(tty),
1508 tty->process_char_map);
1509 }
1510 }
1511 if (I_IXON(tty)) {
1512 set_bit(START_CHAR(tty), tty->process_char_map);
1513 set_bit(STOP_CHAR(tty), tty->process_char_map);
1514 }
1515 if (L_ISIG(tty)) {
1516 set_bit(INTR_CHAR(tty), tty->process_char_map);
1517 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1518 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1519 }
1520 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1521 tty->raw = 0;
1522 tty->real_raw = 0;
1523 } else {
1524 tty->raw = 1;
1525 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1526 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1527 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1528 tty->real_raw = 1;
1529 else
1530 tty->real_raw = 0;
1531 }
1532 n_tty_set_room(tty);
1533 /* The termios change make the tty ready for I/O */
1534 wake_up_interruptible(&tty->write_wait);
1535 wake_up_interruptible(&tty->read_wait);
1536}
1537
1538/**
1539 * n_tty_close - close the ldisc for this tty
1540 * @tty: device
1541 *
1542 * Called from the terminal layer when this line discipline is
1543 * being shut down, either because of a close or becsuse of a
1544 * discipline change. The function will not be called while other
1545 * ldisc methods are in progress.
1546 */
1547
1548static void n_tty_close(struct tty_struct *tty)
1549{
1550 n_tty_flush_buffer(tty);
1551 if (tty->read_buf) {
1552 kfree(tty->read_buf);
1553 tty->read_buf = NULL;
1554 }
1555 if (tty->echo_buf) {
1556 kfree(tty->echo_buf);
1557 tty->echo_buf = NULL;
1558 }
1559}
1560
1561/**
1562 * n_tty_open - open an ldisc
1563 * @tty: terminal to open
1564 *
1565 * Called when this line discipline is being attached to the
1566 * terminal device. Can sleep. Called serialized so that no
1567 * other events will occur in parallel. No further open will occur
1568 * until a close.
1569 */
1570
1571static int n_tty_open(struct tty_struct *tty)
1572{
1573 if (!tty)
1574 return -EINVAL;
1575
1576 /* These are ugly. Currently a malloc failure here can panic */
1577 if (!tty->read_buf) {
1578 tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1579 if (!tty->read_buf)
1580 return -ENOMEM;
1581 }
1582 if (!tty->echo_buf) {
1583 tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1584
1585 if (!tty->echo_buf)
1586 return -ENOMEM;
1587 }
1588 reset_buffer_flags(tty);
1589 tty_unthrottle(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);
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#include <linux/ratelimit.h>
53#include <linux/vmalloc.h>
54
55
56/* number of characters left in xmit buffer before select has we have room */
57#define WAKEUP_CHARS 256
58
59/*
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
63 */
64#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65#define TTY_THRESHOLD_UNTHROTTLE 128
66
67/*
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
71 * codes.
72 */
73#define ECHO_OP_START 0xff
74#define ECHO_OP_MOVE_BACK_COL 0x80
75#define ECHO_OP_SET_CANON_COL 0x81
76#define ECHO_OP_ERASE_TAB 0x82
77
78#define ECHO_COMMIT_WATERMARK 256
79#define ECHO_BLOCK 256
80#define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
81
82
83#undef N_TTY_TRACE
84#ifdef N_TTY_TRACE
85# define n_tty_trace(f, args...) trace_printk(f, ##args)
86#else
87# define n_tty_trace(f, args...)
88#endif
89
90struct n_tty_data {
91 /* producer-published */
92 size_t read_head;
93 size_t commit_head;
94 size_t canon_head;
95 size_t echo_head;
96 size_t echo_commit;
97 size_t echo_mark;
98 DECLARE_BITMAP(char_map, 256);
99
100 /* private to n_tty_receive_overrun (single-threaded) */
101 unsigned long overrun_time;
102 int num_overrun;
103
104 /* non-atomic */
105 bool no_room;
106
107 /* must hold exclusive termios_rwsem to reset these */
108 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
109 unsigned char push:1;
110
111 /* shared by producer and consumer */
112 char read_buf[N_TTY_BUF_SIZE];
113 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
114 unsigned char echo_buf[N_TTY_BUF_SIZE];
115
116 /* consumer-published */
117 size_t read_tail;
118 size_t line_start;
119
120 /* protected by output lock */
121 unsigned int column;
122 unsigned int canon_column;
123 size_t echo_tail;
124
125 struct mutex atomic_read_lock;
126 struct mutex output_lock;
127};
128
129static inline size_t read_cnt(struct n_tty_data *ldata)
130{
131 return ldata->read_head - ldata->read_tail;
132}
133
134static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
135{
136 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
137}
138
139static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
140{
141 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
142}
143
144static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
145{
146 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
147}
148
149static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
150{
151 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
152}
153
154static int tty_copy_to_user(struct tty_struct *tty, void __user *to,
155 size_t tail, size_t n)
156{
157 struct n_tty_data *ldata = tty->disc_data;
158 size_t size = N_TTY_BUF_SIZE - tail;
159 const void *from = read_buf_addr(ldata, tail);
160 int uncopied;
161
162 if (n > size) {
163 tty_audit_add_data(tty, from, size);
164 uncopied = copy_to_user(to, from, size);
165 if (uncopied)
166 return uncopied;
167 to += size;
168 n -= size;
169 from = ldata->read_buf;
170 }
171
172 tty_audit_add_data(tty, from, n);
173 return copy_to_user(to, from, n);
174}
175
176/**
177 * n_tty_kick_worker - start input worker (if required)
178 * @tty: terminal
179 *
180 * Re-schedules the flip buffer work if it may have stopped
181 *
182 * Caller holds exclusive termios_rwsem
183 * or
184 * n_tty_read()/consumer path:
185 * holds non-exclusive termios_rwsem
186 */
187
188static void n_tty_kick_worker(struct tty_struct *tty)
189{
190 struct n_tty_data *ldata = tty->disc_data;
191
192 /* Did the input worker stop? Restart it */
193 if (unlikely(ldata->no_room)) {
194 ldata->no_room = 0;
195
196 WARN_RATELIMIT(tty->port->itty == NULL,
197 "scheduling with invalid itty\n");
198 /* see if ldisc has been killed - if so, this means that
199 * even though the ldisc has been halted and ->buf.work
200 * cancelled, ->buf.work is about to be rescheduled
201 */
202 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
203 "scheduling buffer work for halted ldisc\n");
204 tty_buffer_restart_work(tty->port);
205 }
206}
207
208static ssize_t chars_in_buffer(struct tty_struct *tty)
209{
210 struct n_tty_data *ldata = tty->disc_data;
211 ssize_t n = 0;
212
213 if (!ldata->icanon)
214 n = ldata->commit_head - ldata->read_tail;
215 else
216 n = ldata->canon_head - ldata->read_tail;
217 return n;
218}
219
220/**
221 * n_tty_write_wakeup - asynchronous I/O notifier
222 * @tty: tty device
223 *
224 * Required for the ptys, serial driver etc. since processes
225 * that attach themselves to the master and rely on ASYNC
226 * IO must be woken up
227 */
228
229static void n_tty_write_wakeup(struct tty_struct *tty)
230{
231 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
232 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
233}
234
235static void n_tty_check_throttle(struct tty_struct *tty)
236{
237 struct n_tty_data *ldata = tty->disc_data;
238
239 /*
240 * Check the remaining room for the input canonicalization
241 * mode. We don't want to throttle the driver if we're in
242 * canonical mode and don't have a newline yet!
243 */
244 if (ldata->icanon && ldata->canon_head == ldata->read_tail)
245 return;
246
247 while (1) {
248 int throttled;
249 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
250 if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
251 break;
252 throttled = tty_throttle_safe(tty);
253 if (!throttled)
254 break;
255 }
256 __tty_set_flow_change(tty, 0);
257}
258
259static void n_tty_check_unthrottle(struct tty_struct *tty)
260{
261 if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
262 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
263 return;
264 n_tty_kick_worker(tty);
265 tty_wakeup(tty->link);
266 return;
267 }
268
269 /* If there is enough space in the read buffer now, let the
270 * low-level driver know. We use chars_in_buffer() to
271 * check the buffer, as it now knows about canonical mode.
272 * Otherwise, if the driver is throttled and the line is
273 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
274 * we won't get any more characters.
275 */
276
277 while (1) {
278 int unthrottled;
279 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
280 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
281 break;
282 n_tty_kick_worker(tty);
283 unthrottled = tty_unthrottle_safe(tty);
284 if (!unthrottled)
285 break;
286 }
287 __tty_set_flow_change(tty, 0);
288}
289
290/**
291 * put_tty_queue - add character to tty
292 * @c: character
293 * @ldata: n_tty data
294 *
295 * Add a character to the tty read_buf queue.
296 *
297 * n_tty_receive_buf()/producer path:
298 * caller holds non-exclusive termios_rwsem
299 */
300
301static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
302{
303 *read_buf_addr(ldata, ldata->read_head) = c;
304 ldata->read_head++;
305}
306
307/**
308 * reset_buffer_flags - reset buffer state
309 * @tty: terminal to reset
310 *
311 * Reset the read buffer counters and clear the flags.
312 * Called from n_tty_open() and n_tty_flush_buffer().
313 *
314 * Locking: caller holds exclusive termios_rwsem
315 * (or locking is not required)
316 */
317
318static void reset_buffer_flags(struct n_tty_data *ldata)
319{
320 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
321 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
322 ldata->commit_head = 0;
323 ldata->echo_mark = 0;
324 ldata->line_start = 0;
325
326 ldata->erasing = 0;
327 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
328 ldata->push = 0;
329}
330
331static void n_tty_packet_mode_flush(struct tty_struct *tty)
332{
333 unsigned long flags;
334
335 if (tty->link->packet) {
336 spin_lock_irqsave(&tty->ctrl_lock, flags);
337 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
338 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
339 wake_up_interruptible(&tty->link->read_wait);
340 }
341}
342
343/**
344 * n_tty_flush_buffer - clean input queue
345 * @tty: terminal device
346 *
347 * Flush the input buffer. Called when the tty layer wants the
348 * buffer flushed (eg at hangup) or when the N_TTY line discipline
349 * internally has to clean the pending queue (for example some signals).
350 *
351 * Holds termios_rwsem to exclude producer/consumer while
352 * buffer indices are reset.
353 *
354 * Locking: ctrl_lock, exclusive termios_rwsem
355 */
356
357static void n_tty_flush_buffer(struct tty_struct *tty)
358{
359 down_write(&tty->termios_rwsem);
360 reset_buffer_flags(tty->disc_data);
361 n_tty_kick_worker(tty);
362
363 if (tty->link)
364 n_tty_packet_mode_flush(tty);
365 up_write(&tty->termios_rwsem);
366}
367
368/**
369 * is_utf8_continuation - utf8 multibyte check
370 * @c: byte to check
371 *
372 * Returns true if the utf8 character 'c' is a multibyte continuation
373 * character. We use this to correctly compute the on screen size
374 * of the character when printing
375 */
376
377static inline int is_utf8_continuation(unsigned char c)
378{
379 return (c & 0xc0) == 0x80;
380}
381
382/**
383 * is_continuation - multibyte check
384 * @c: byte to check
385 *
386 * Returns true if the utf8 character 'c' is a multibyte continuation
387 * character and the terminal is in unicode mode.
388 */
389
390static inline int is_continuation(unsigned char c, struct tty_struct *tty)
391{
392 return I_IUTF8(tty) && is_utf8_continuation(c);
393}
394
395/**
396 * do_output_char - output one character
397 * @c: character (or partial unicode symbol)
398 * @tty: terminal device
399 * @space: space available in tty driver write buffer
400 *
401 * This is a helper function that handles one output character
402 * (including special characters like TAB, CR, LF, etc.),
403 * doing OPOST processing and putting the results in the
404 * tty driver's write buffer.
405 *
406 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
407 * and NLDLY. They simply aren't relevant in the world today.
408 * If you ever need them, add them here.
409 *
410 * Returns the number of bytes of buffer space used or -1 if
411 * no space left.
412 *
413 * Locking: should be called under the output_lock to protect
414 * the column state and space left in the buffer
415 */
416
417static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
418{
419 struct n_tty_data *ldata = tty->disc_data;
420 int spaces;
421
422 if (!space)
423 return -1;
424
425 switch (c) {
426 case '\n':
427 if (O_ONLRET(tty))
428 ldata->column = 0;
429 if (O_ONLCR(tty)) {
430 if (space < 2)
431 return -1;
432 ldata->canon_column = ldata->column = 0;
433 tty->ops->write(tty, "\r\n", 2);
434 return 2;
435 }
436 ldata->canon_column = ldata->column;
437 break;
438 case '\r':
439 if (O_ONOCR(tty) && ldata->column == 0)
440 return 0;
441 if (O_OCRNL(tty)) {
442 c = '\n';
443 if (O_ONLRET(tty))
444 ldata->canon_column = ldata->column = 0;
445 break;
446 }
447 ldata->canon_column = ldata->column = 0;
448 break;
449 case '\t':
450 spaces = 8 - (ldata->column & 7);
451 if (O_TABDLY(tty) == XTABS) {
452 if (space < spaces)
453 return -1;
454 ldata->column += spaces;
455 tty->ops->write(tty, " ", spaces);
456 return spaces;
457 }
458 ldata->column += spaces;
459 break;
460 case '\b':
461 if (ldata->column > 0)
462 ldata->column--;
463 break;
464 default:
465 if (!iscntrl(c)) {
466 if (O_OLCUC(tty))
467 c = toupper(c);
468 if (!is_continuation(c, tty))
469 ldata->column++;
470 }
471 break;
472 }
473
474 tty_put_char(tty, c);
475 return 1;
476}
477
478/**
479 * process_output - output post processor
480 * @c: character (or partial unicode symbol)
481 * @tty: terminal device
482 *
483 * Output one character with OPOST processing.
484 * Returns -1 when the output device is full and the character
485 * must be retried.
486 *
487 * Locking: output_lock to protect column state and space left
488 * (also, this is called from n_tty_write under the
489 * tty layer write lock)
490 */
491
492static int process_output(unsigned char c, struct tty_struct *tty)
493{
494 struct n_tty_data *ldata = tty->disc_data;
495 int space, retval;
496
497 mutex_lock(&ldata->output_lock);
498
499 space = tty_write_room(tty);
500 retval = do_output_char(c, tty, space);
501
502 mutex_unlock(&ldata->output_lock);
503 if (retval < 0)
504 return -1;
505 else
506 return 0;
507}
508
509/**
510 * process_output_block - block post processor
511 * @tty: terminal device
512 * @buf: character buffer
513 * @nr: number of bytes to output
514 *
515 * Output a block of characters with OPOST processing.
516 * Returns the number of characters output.
517 *
518 * This path is used to speed up block console writes, among other
519 * things when processing blocks of output data. It handles only
520 * the simple cases normally found and helps to generate blocks of
521 * symbols for the console driver and thus improve performance.
522 *
523 * Locking: output_lock to protect column state and space left
524 * (also, this is called from n_tty_write under the
525 * tty layer write lock)
526 */
527
528static ssize_t process_output_block(struct tty_struct *tty,
529 const unsigned char *buf, unsigned int nr)
530{
531 struct n_tty_data *ldata = tty->disc_data;
532 int space;
533 int i;
534 const unsigned char *cp;
535
536 mutex_lock(&ldata->output_lock);
537
538 space = tty_write_room(tty);
539 if (!space) {
540 mutex_unlock(&ldata->output_lock);
541 return 0;
542 }
543 if (nr > space)
544 nr = space;
545
546 for (i = 0, cp = buf; i < nr; i++, cp++) {
547 unsigned char c = *cp;
548
549 switch (c) {
550 case '\n':
551 if (O_ONLRET(tty))
552 ldata->column = 0;
553 if (O_ONLCR(tty))
554 goto break_out;
555 ldata->canon_column = ldata->column;
556 break;
557 case '\r':
558 if (O_ONOCR(tty) && ldata->column == 0)
559 goto break_out;
560 if (O_OCRNL(tty))
561 goto break_out;
562 ldata->canon_column = ldata->column = 0;
563 break;
564 case '\t':
565 goto break_out;
566 case '\b':
567 if (ldata->column > 0)
568 ldata->column--;
569 break;
570 default:
571 if (!iscntrl(c)) {
572 if (O_OLCUC(tty))
573 goto break_out;
574 if (!is_continuation(c, tty))
575 ldata->column++;
576 }
577 break;
578 }
579 }
580break_out:
581 i = tty->ops->write(tty, buf, i);
582
583 mutex_unlock(&ldata->output_lock);
584 return i;
585}
586
587/**
588 * process_echoes - write pending echo characters
589 * @tty: terminal device
590 *
591 * Write previously buffered echo (and other ldisc-generated)
592 * characters to the tty.
593 *
594 * Characters generated by the ldisc (including echoes) need to
595 * be buffered because the driver's write buffer can fill during
596 * heavy program output. Echoing straight to the driver will
597 * often fail under these conditions, causing lost characters and
598 * resulting mismatches of ldisc state information.
599 *
600 * Since the ldisc state must represent the characters actually sent
601 * to the driver at the time of the write, operations like certain
602 * changes in column state are also saved in the buffer and executed
603 * here.
604 *
605 * A circular fifo buffer is used so that the most recent characters
606 * are prioritized. Also, when control characters are echoed with a
607 * prefixed "^", the pair is treated atomically and thus not separated.
608 *
609 * Locking: callers must hold output_lock
610 */
611
612static size_t __process_echoes(struct tty_struct *tty)
613{
614 struct n_tty_data *ldata = tty->disc_data;
615 int space, old_space;
616 size_t tail;
617 unsigned char c;
618
619 old_space = space = tty_write_room(tty);
620
621 tail = ldata->echo_tail;
622 while (ldata->echo_commit != tail) {
623 c = echo_buf(ldata, tail);
624 if (c == ECHO_OP_START) {
625 unsigned char op;
626 int no_space_left = 0;
627
628 /*
629 * If the buffer byte is the start of a multi-byte
630 * operation, get the next byte, which is either the
631 * op code or a control character value.
632 */
633 op = echo_buf(ldata, tail + 1);
634
635 switch (op) {
636 unsigned int num_chars, num_bs;
637
638 case ECHO_OP_ERASE_TAB:
639 num_chars = echo_buf(ldata, tail + 2);
640
641 /*
642 * Determine how many columns to go back
643 * in order to erase the tab.
644 * This depends on the number of columns
645 * used by other characters within the tab
646 * area. If this (modulo 8) count is from
647 * the start of input rather than from a
648 * previous tab, we offset by canon column.
649 * Otherwise, tab spacing is normal.
650 */
651 if (!(num_chars & 0x80))
652 num_chars += ldata->canon_column;
653 num_bs = 8 - (num_chars & 7);
654
655 if (num_bs > space) {
656 no_space_left = 1;
657 break;
658 }
659 space -= num_bs;
660 while (num_bs--) {
661 tty_put_char(tty, '\b');
662 if (ldata->column > 0)
663 ldata->column--;
664 }
665 tail += 3;
666 break;
667
668 case ECHO_OP_SET_CANON_COL:
669 ldata->canon_column = ldata->column;
670 tail += 2;
671 break;
672
673 case ECHO_OP_MOVE_BACK_COL:
674 if (ldata->column > 0)
675 ldata->column--;
676 tail += 2;
677 break;
678
679 case ECHO_OP_START:
680 /* This is an escaped echo op start code */
681 if (!space) {
682 no_space_left = 1;
683 break;
684 }
685 tty_put_char(tty, ECHO_OP_START);
686 ldata->column++;
687 space--;
688 tail += 2;
689 break;
690
691 default:
692 /*
693 * If the op is not a special byte code,
694 * it is a ctrl char tagged to be echoed
695 * as "^X" (where X is the letter
696 * representing the control char).
697 * Note that we must ensure there is
698 * enough space for the whole ctrl pair.
699 *
700 */
701 if (space < 2) {
702 no_space_left = 1;
703 break;
704 }
705 tty_put_char(tty, '^');
706 tty_put_char(tty, op ^ 0100);
707 ldata->column += 2;
708 space -= 2;
709 tail += 2;
710 }
711
712 if (no_space_left)
713 break;
714 } else {
715 if (O_OPOST(tty)) {
716 int retval = do_output_char(c, tty, space);
717 if (retval < 0)
718 break;
719 space -= retval;
720 } else {
721 if (!space)
722 break;
723 tty_put_char(tty, c);
724 space -= 1;
725 }
726 tail += 1;
727 }
728 }
729
730 /* If the echo buffer is nearly full (so that the possibility exists
731 * of echo overrun before the next commit), then discard enough
732 * data at the tail to prevent a subsequent overrun */
733 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
734 if (echo_buf(ldata, tail) == ECHO_OP_START) {
735 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
736 tail += 3;
737 else
738 tail += 2;
739 } else
740 tail++;
741 }
742
743 ldata->echo_tail = tail;
744 return old_space - space;
745}
746
747static void commit_echoes(struct tty_struct *tty)
748{
749 struct n_tty_data *ldata = tty->disc_data;
750 size_t nr, old, echoed;
751 size_t head;
752
753 head = ldata->echo_head;
754 ldata->echo_mark = head;
755 old = ldata->echo_commit - ldata->echo_tail;
756
757 /* Process committed echoes if the accumulated # of bytes
758 * is over the threshold (and try again each time another
759 * block is accumulated) */
760 nr = head - ldata->echo_tail;
761 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
762 return;
763
764 mutex_lock(&ldata->output_lock);
765 ldata->echo_commit = head;
766 echoed = __process_echoes(tty);
767 mutex_unlock(&ldata->output_lock);
768
769 if (echoed && tty->ops->flush_chars)
770 tty->ops->flush_chars(tty);
771}
772
773static void process_echoes(struct tty_struct *tty)
774{
775 struct n_tty_data *ldata = tty->disc_data;
776 size_t echoed;
777
778 if (ldata->echo_mark == ldata->echo_tail)
779 return;
780
781 mutex_lock(&ldata->output_lock);
782 ldata->echo_commit = ldata->echo_mark;
783 echoed = __process_echoes(tty);
784 mutex_unlock(&ldata->output_lock);
785
786 if (echoed && tty->ops->flush_chars)
787 tty->ops->flush_chars(tty);
788}
789
790/* NB: echo_mark and echo_head should be equivalent here */
791static void flush_echoes(struct tty_struct *tty)
792{
793 struct n_tty_data *ldata = tty->disc_data;
794
795 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
796 ldata->echo_commit == ldata->echo_head)
797 return;
798
799 mutex_lock(&ldata->output_lock);
800 ldata->echo_commit = ldata->echo_head;
801 __process_echoes(tty);
802 mutex_unlock(&ldata->output_lock);
803}
804
805/**
806 * add_echo_byte - add a byte to the echo buffer
807 * @c: unicode byte to echo
808 * @ldata: n_tty data
809 *
810 * Add a character or operation byte to the echo buffer.
811 */
812
813static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
814{
815 *echo_buf_addr(ldata, ldata->echo_head++) = c;
816}
817
818/**
819 * echo_move_back_col - add operation to move back a column
820 * @ldata: n_tty data
821 *
822 * Add an operation to the echo buffer to move back one column.
823 */
824
825static void echo_move_back_col(struct n_tty_data *ldata)
826{
827 add_echo_byte(ECHO_OP_START, ldata);
828 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
829}
830
831/**
832 * echo_set_canon_col - add operation to set the canon column
833 * @ldata: n_tty data
834 *
835 * Add an operation to the echo buffer to set the canon column
836 * to the current column.
837 */
838
839static void echo_set_canon_col(struct n_tty_data *ldata)
840{
841 add_echo_byte(ECHO_OP_START, ldata);
842 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
843}
844
845/**
846 * echo_erase_tab - add operation to erase a tab
847 * @num_chars: number of character columns already used
848 * @after_tab: true if num_chars starts after a previous tab
849 * @ldata: n_tty data
850 *
851 * Add an operation to the echo buffer to erase a tab.
852 *
853 * Called by the eraser function, which knows how many character
854 * columns have been used since either a previous tab or the start
855 * of input. This information will be used later, along with
856 * canon column (if applicable), to go back the correct number
857 * of columns.
858 */
859
860static void echo_erase_tab(unsigned int num_chars, int after_tab,
861 struct n_tty_data *ldata)
862{
863 add_echo_byte(ECHO_OP_START, ldata);
864 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
865
866 /* We only need to know this modulo 8 (tab spacing) */
867 num_chars &= 7;
868
869 /* Set the high bit as a flag if num_chars is after a previous tab */
870 if (after_tab)
871 num_chars |= 0x80;
872
873 add_echo_byte(num_chars, ldata);
874}
875
876/**
877 * echo_char_raw - echo a character raw
878 * @c: unicode byte to echo
879 * @tty: terminal device
880 *
881 * Echo user input back onto the screen. This must be called only when
882 * L_ECHO(tty) is true. Called from the driver receive_buf path.
883 *
884 * This variant does not treat control characters specially.
885 */
886
887static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
888{
889 if (c == ECHO_OP_START) {
890 add_echo_byte(ECHO_OP_START, ldata);
891 add_echo_byte(ECHO_OP_START, ldata);
892 } else {
893 add_echo_byte(c, ldata);
894 }
895}
896
897/**
898 * echo_char - echo a character
899 * @c: unicode byte to echo
900 * @tty: terminal device
901 *
902 * Echo user input back onto the screen. This must be called only when
903 * L_ECHO(tty) is true. Called from the driver receive_buf path.
904 *
905 * This variant tags control characters to be echoed as "^X"
906 * (where X is the letter representing the control char).
907 */
908
909static void echo_char(unsigned char c, struct tty_struct *tty)
910{
911 struct n_tty_data *ldata = tty->disc_data;
912
913 if (c == ECHO_OP_START) {
914 add_echo_byte(ECHO_OP_START, ldata);
915 add_echo_byte(ECHO_OP_START, ldata);
916 } else {
917 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
918 add_echo_byte(ECHO_OP_START, ldata);
919 add_echo_byte(c, ldata);
920 }
921}
922
923/**
924 * finish_erasing - complete erase
925 * @ldata: n_tty data
926 */
927
928static inline void finish_erasing(struct n_tty_data *ldata)
929{
930 if (ldata->erasing) {
931 echo_char_raw('/', ldata);
932 ldata->erasing = 0;
933 }
934}
935
936/**
937 * eraser - handle erase function
938 * @c: character input
939 * @tty: terminal device
940 *
941 * Perform erase and necessary output when an erase character is
942 * present in the stream from the driver layer. Handles the complexities
943 * of UTF-8 multibyte symbols.
944 *
945 * n_tty_receive_buf()/producer path:
946 * caller holds non-exclusive termios_rwsem
947 */
948
949static void eraser(unsigned char c, struct tty_struct *tty)
950{
951 struct n_tty_data *ldata = tty->disc_data;
952 enum { ERASE, WERASE, KILL } kill_type;
953 size_t head;
954 size_t cnt;
955 int seen_alnums;
956
957 if (ldata->read_head == ldata->canon_head) {
958 /* process_output('\a', tty); */ /* what do you think? */
959 return;
960 }
961 if (c == ERASE_CHAR(tty))
962 kill_type = ERASE;
963 else if (c == WERASE_CHAR(tty))
964 kill_type = WERASE;
965 else {
966 if (!L_ECHO(tty)) {
967 ldata->read_head = ldata->canon_head;
968 return;
969 }
970 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
971 ldata->read_head = ldata->canon_head;
972 finish_erasing(ldata);
973 echo_char(KILL_CHAR(tty), tty);
974 /* Add a newline if ECHOK is on and ECHOKE is off. */
975 if (L_ECHOK(tty))
976 echo_char_raw('\n', ldata);
977 return;
978 }
979 kill_type = KILL;
980 }
981
982 seen_alnums = 0;
983 while (ldata->read_head != ldata->canon_head) {
984 head = ldata->read_head;
985
986 /* erase a single possibly multibyte character */
987 do {
988 head--;
989 c = read_buf(ldata, head);
990 } while (is_continuation(c, tty) && head != ldata->canon_head);
991
992 /* do not partially erase */
993 if (is_continuation(c, tty))
994 break;
995
996 if (kill_type == WERASE) {
997 /* Equivalent to BSD's ALTWERASE. */
998 if (isalnum(c) || c == '_')
999 seen_alnums++;
1000 else if (seen_alnums)
1001 break;
1002 }
1003 cnt = ldata->read_head - head;
1004 ldata->read_head = head;
1005 if (L_ECHO(tty)) {
1006 if (L_ECHOPRT(tty)) {
1007 if (!ldata->erasing) {
1008 echo_char_raw('\\', ldata);
1009 ldata->erasing = 1;
1010 }
1011 /* if cnt > 1, output a multi-byte character */
1012 echo_char(c, tty);
1013 while (--cnt > 0) {
1014 head++;
1015 echo_char_raw(read_buf(ldata, head), ldata);
1016 echo_move_back_col(ldata);
1017 }
1018 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1019 echo_char(ERASE_CHAR(tty), tty);
1020 } else if (c == '\t') {
1021 unsigned int num_chars = 0;
1022 int after_tab = 0;
1023 size_t tail = ldata->read_head;
1024
1025 /*
1026 * Count the columns used for characters
1027 * since the start of input or after a
1028 * previous tab.
1029 * This info is used to go back the correct
1030 * number of columns.
1031 */
1032 while (tail != ldata->canon_head) {
1033 tail--;
1034 c = read_buf(ldata, tail);
1035 if (c == '\t') {
1036 after_tab = 1;
1037 break;
1038 } else if (iscntrl(c)) {
1039 if (L_ECHOCTL(tty))
1040 num_chars += 2;
1041 } else if (!is_continuation(c, tty)) {
1042 num_chars++;
1043 }
1044 }
1045 echo_erase_tab(num_chars, after_tab, ldata);
1046 } else {
1047 if (iscntrl(c) && L_ECHOCTL(tty)) {
1048 echo_char_raw('\b', ldata);
1049 echo_char_raw(' ', ldata);
1050 echo_char_raw('\b', ldata);
1051 }
1052 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1053 echo_char_raw('\b', ldata);
1054 echo_char_raw(' ', ldata);
1055 echo_char_raw('\b', ldata);
1056 }
1057 }
1058 }
1059 if (kill_type == ERASE)
1060 break;
1061 }
1062 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1063 finish_erasing(ldata);
1064}
1065
1066/**
1067 * isig - handle the ISIG optio
1068 * @sig: signal
1069 * @tty: terminal
1070 *
1071 * Called when a signal is being sent due to terminal input.
1072 * Called from the driver receive_buf path so serialized.
1073 *
1074 * Performs input and output flush if !NOFLSH. In this context, the echo
1075 * buffer is 'output'. The signal is processed first to alert any current
1076 * readers or writers to discontinue and exit their i/o loops.
1077 *
1078 * Locking: ctrl_lock
1079 */
1080
1081static void __isig(int sig, struct tty_struct *tty)
1082{
1083 struct pid *tty_pgrp = tty_get_pgrp(tty);
1084 if (tty_pgrp) {
1085 kill_pgrp(tty_pgrp, sig, 1);
1086 put_pid(tty_pgrp);
1087 }
1088}
1089
1090static void isig(int sig, struct tty_struct *tty)
1091{
1092 struct n_tty_data *ldata = tty->disc_data;
1093
1094 if (L_NOFLSH(tty)) {
1095 /* signal only */
1096 __isig(sig, tty);
1097
1098 } else { /* signal and flush */
1099 up_read(&tty->termios_rwsem);
1100 down_write(&tty->termios_rwsem);
1101
1102 __isig(sig, tty);
1103
1104 /* clear echo buffer */
1105 mutex_lock(&ldata->output_lock);
1106 ldata->echo_head = ldata->echo_tail = 0;
1107 ldata->echo_mark = ldata->echo_commit = 0;
1108 mutex_unlock(&ldata->output_lock);
1109
1110 /* clear output buffer */
1111 tty_driver_flush_buffer(tty);
1112
1113 /* clear input buffer */
1114 reset_buffer_flags(tty->disc_data);
1115
1116 /* notify pty master of flush */
1117 if (tty->link)
1118 n_tty_packet_mode_flush(tty);
1119
1120 up_write(&tty->termios_rwsem);
1121 down_read(&tty->termios_rwsem);
1122 }
1123}
1124
1125/**
1126 * n_tty_receive_break - handle break
1127 * @tty: terminal
1128 *
1129 * An RS232 break event has been hit in the incoming bitstream. This
1130 * can cause a variety of events depending upon the termios settings.
1131 *
1132 * n_tty_receive_buf()/producer path:
1133 * caller holds non-exclusive termios_rwsem
1134 *
1135 * Note: may get exclusive termios_rwsem if flushing input buffer
1136 */
1137
1138static void n_tty_receive_break(struct tty_struct *tty)
1139{
1140 struct n_tty_data *ldata = tty->disc_data;
1141
1142 if (I_IGNBRK(tty))
1143 return;
1144 if (I_BRKINT(tty)) {
1145 isig(SIGINT, tty);
1146 return;
1147 }
1148 if (I_PARMRK(tty)) {
1149 put_tty_queue('\377', ldata);
1150 put_tty_queue('\0', ldata);
1151 }
1152 put_tty_queue('\0', ldata);
1153}
1154
1155/**
1156 * n_tty_receive_overrun - handle overrun reporting
1157 * @tty: terminal
1158 *
1159 * Data arrived faster than we could process it. While the tty
1160 * driver has flagged this the bits that were missed are gone
1161 * forever.
1162 *
1163 * Called from the receive_buf path so single threaded. Does not
1164 * need locking as num_overrun and overrun_time are function
1165 * private.
1166 */
1167
1168static void n_tty_receive_overrun(struct tty_struct *tty)
1169{
1170 struct n_tty_data *ldata = tty->disc_data;
1171
1172 ldata->num_overrun++;
1173 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1174 time_after(ldata->overrun_time, jiffies)) {
1175 tty_warn(tty, "%d input overrun(s)\n", ldata->num_overrun);
1176 ldata->overrun_time = jiffies;
1177 ldata->num_overrun = 0;
1178 }
1179}
1180
1181/**
1182 * n_tty_receive_parity_error - error notifier
1183 * @tty: terminal device
1184 * @c: character
1185 *
1186 * Process a parity error and queue the right data to indicate
1187 * the error case if necessary.
1188 *
1189 * n_tty_receive_buf()/producer path:
1190 * caller holds non-exclusive termios_rwsem
1191 */
1192static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1193{
1194 struct n_tty_data *ldata = tty->disc_data;
1195
1196 if (I_INPCK(tty)) {
1197 if (I_IGNPAR(tty))
1198 return;
1199 if (I_PARMRK(tty)) {
1200 put_tty_queue('\377', ldata);
1201 put_tty_queue('\0', ldata);
1202 put_tty_queue(c, ldata);
1203 } else
1204 put_tty_queue('\0', ldata);
1205 } else
1206 put_tty_queue(c, ldata);
1207}
1208
1209static void
1210n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1211{
1212 isig(signal, tty);
1213 if (I_IXON(tty))
1214 start_tty(tty);
1215 if (L_ECHO(tty)) {
1216 echo_char(c, tty);
1217 commit_echoes(tty);
1218 } else
1219 process_echoes(tty);
1220 return;
1221}
1222
1223/**
1224 * n_tty_receive_char - perform processing
1225 * @tty: terminal device
1226 * @c: character
1227 *
1228 * Process an individual character of input received from the driver.
1229 * This is serialized with respect to itself by the rules for the
1230 * driver above.
1231 *
1232 * n_tty_receive_buf()/producer path:
1233 * caller holds non-exclusive termios_rwsem
1234 * publishes canon_head if canonical mode is active
1235 *
1236 * Returns 1 if LNEXT was received, else returns 0
1237 */
1238
1239static int
1240n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1241{
1242 struct n_tty_data *ldata = tty->disc_data;
1243
1244 if (I_IXON(tty)) {
1245 if (c == START_CHAR(tty)) {
1246 start_tty(tty);
1247 process_echoes(tty);
1248 return 0;
1249 }
1250 if (c == STOP_CHAR(tty)) {
1251 stop_tty(tty);
1252 return 0;
1253 }
1254 }
1255
1256 if (L_ISIG(tty)) {
1257 if (c == INTR_CHAR(tty)) {
1258 n_tty_receive_signal_char(tty, SIGINT, c);
1259 return 0;
1260 } else if (c == QUIT_CHAR(tty)) {
1261 n_tty_receive_signal_char(tty, SIGQUIT, c);
1262 return 0;
1263 } else if (c == SUSP_CHAR(tty)) {
1264 n_tty_receive_signal_char(tty, SIGTSTP, c);
1265 return 0;
1266 }
1267 }
1268
1269 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1270 start_tty(tty);
1271 process_echoes(tty);
1272 }
1273
1274 if (c == '\r') {
1275 if (I_IGNCR(tty))
1276 return 0;
1277 if (I_ICRNL(tty))
1278 c = '\n';
1279 } else if (c == '\n' && I_INLCR(tty))
1280 c = '\r';
1281
1282 if (ldata->icanon) {
1283 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1284 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1285 eraser(c, tty);
1286 commit_echoes(tty);
1287 return 0;
1288 }
1289 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1290 ldata->lnext = 1;
1291 if (L_ECHO(tty)) {
1292 finish_erasing(ldata);
1293 if (L_ECHOCTL(tty)) {
1294 echo_char_raw('^', ldata);
1295 echo_char_raw('\b', ldata);
1296 commit_echoes(tty);
1297 }
1298 }
1299 return 1;
1300 }
1301 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1302 size_t tail = ldata->canon_head;
1303
1304 finish_erasing(ldata);
1305 echo_char(c, tty);
1306 echo_char_raw('\n', ldata);
1307 while (tail != ldata->read_head) {
1308 echo_char(read_buf(ldata, tail), tty);
1309 tail++;
1310 }
1311 commit_echoes(tty);
1312 return 0;
1313 }
1314 if (c == '\n') {
1315 if (L_ECHO(tty) || L_ECHONL(tty)) {
1316 echo_char_raw('\n', ldata);
1317 commit_echoes(tty);
1318 }
1319 goto handle_newline;
1320 }
1321 if (c == EOF_CHAR(tty)) {
1322 c = __DISABLED_CHAR;
1323 goto handle_newline;
1324 }
1325 if ((c == EOL_CHAR(tty)) ||
1326 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1327 /*
1328 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1329 */
1330 if (L_ECHO(tty)) {
1331 /* Record the column of first canon char. */
1332 if (ldata->canon_head == ldata->read_head)
1333 echo_set_canon_col(ldata);
1334 echo_char(c, tty);
1335 commit_echoes(tty);
1336 }
1337 /*
1338 * XXX does PARMRK doubling happen for
1339 * EOL_CHAR and EOL2_CHAR?
1340 */
1341 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1342 put_tty_queue(c, ldata);
1343
1344handle_newline:
1345 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1346 put_tty_queue(c, ldata);
1347 smp_store_release(&ldata->canon_head, ldata->read_head);
1348 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1349 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1350 return 0;
1351 }
1352 }
1353
1354 if (L_ECHO(tty)) {
1355 finish_erasing(ldata);
1356 if (c == '\n')
1357 echo_char_raw('\n', ldata);
1358 else {
1359 /* Record the column of first canon char. */
1360 if (ldata->canon_head == ldata->read_head)
1361 echo_set_canon_col(ldata);
1362 echo_char(c, tty);
1363 }
1364 commit_echoes(tty);
1365 }
1366
1367 /* PARMRK doubling check */
1368 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1369 put_tty_queue(c, ldata);
1370
1371 put_tty_queue(c, ldata);
1372 return 0;
1373}
1374
1375static inline void
1376n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1377{
1378 struct n_tty_data *ldata = tty->disc_data;
1379
1380 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1381 start_tty(tty);
1382 process_echoes(tty);
1383 }
1384 if (L_ECHO(tty)) {
1385 finish_erasing(ldata);
1386 /* Record the column of first canon char. */
1387 if (ldata->canon_head == ldata->read_head)
1388 echo_set_canon_col(ldata);
1389 echo_char(c, tty);
1390 commit_echoes(tty);
1391 }
1392 /* PARMRK doubling check */
1393 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1394 put_tty_queue(c, ldata);
1395 put_tty_queue(c, ldata);
1396}
1397
1398static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1399{
1400 n_tty_receive_char_inline(tty, c);
1401}
1402
1403static inline void
1404n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1405{
1406 struct n_tty_data *ldata = tty->disc_data;
1407
1408 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1409 start_tty(tty);
1410 process_echoes(tty);
1411 }
1412 if (L_ECHO(tty)) {
1413 finish_erasing(ldata);
1414 /* Record the column of first canon char. */
1415 if (ldata->canon_head == ldata->read_head)
1416 echo_set_canon_col(ldata);
1417 echo_char(c, tty);
1418 commit_echoes(tty);
1419 }
1420 put_tty_queue(c, ldata);
1421}
1422
1423static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1424{
1425 if (I_ISTRIP(tty))
1426 c &= 0x7f;
1427 if (I_IUCLC(tty) && L_IEXTEN(tty))
1428 c = tolower(c);
1429
1430 if (I_IXON(tty)) {
1431 if (c == STOP_CHAR(tty))
1432 stop_tty(tty);
1433 else if (c == START_CHAR(tty) ||
1434 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1435 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1436 c != SUSP_CHAR(tty))) {
1437 start_tty(tty);
1438 process_echoes(tty);
1439 }
1440 }
1441}
1442
1443static void
1444n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1445{
1446 switch (flag) {
1447 case TTY_BREAK:
1448 n_tty_receive_break(tty);
1449 break;
1450 case TTY_PARITY:
1451 case TTY_FRAME:
1452 n_tty_receive_parity_error(tty, c);
1453 break;
1454 case TTY_OVERRUN:
1455 n_tty_receive_overrun(tty);
1456 break;
1457 default:
1458 tty_err(tty, "unknown flag %d\n", flag);
1459 break;
1460 }
1461}
1462
1463static void
1464n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1465{
1466 struct n_tty_data *ldata = tty->disc_data;
1467
1468 ldata->lnext = 0;
1469 if (likely(flag == TTY_NORMAL)) {
1470 if (I_ISTRIP(tty))
1471 c &= 0x7f;
1472 if (I_IUCLC(tty) && L_IEXTEN(tty))
1473 c = tolower(c);
1474 n_tty_receive_char(tty, c);
1475 } else
1476 n_tty_receive_char_flagged(tty, c, flag);
1477}
1478
1479static void
1480n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1481 char *fp, int count)
1482{
1483 struct n_tty_data *ldata = tty->disc_data;
1484 size_t n, head;
1485
1486 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1487 n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
1488 memcpy(read_buf_addr(ldata, head), cp, n);
1489 ldata->read_head += n;
1490 cp += n;
1491 count -= n;
1492
1493 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1494 n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
1495 memcpy(read_buf_addr(ldata, head), cp, n);
1496 ldata->read_head += n;
1497}
1498
1499static void
1500n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1501 char *fp, int count)
1502{
1503 struct n_tty_data *ldata = tty->disc_data;
1504 char flag = TTY_NORMAL;
1505
1506 while (count--) {
1507 if (fp)
1508 flag = *fp++;
1509 if (likely(flag == TTY_NORMAL))
1510 put_tty_queue(*cp++, ldata);
1511 else
1512 n_tty_receive_char_flagged(tty, *cp++, flag);
1513 }
1514}
1515
1516static void
1517n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1518 char *fp, int count)
1519{
1520 char flag = TTY_NORMAL;
1521
1522 while (count--) {
1523 if (fp)
1524 flag = *fp++;
1525 if (likely(flag == TTY_NORMAL))
1526 n_tty_receive_char_closing(tty, *cp++);
1527 }
1528}
1529
1530static void
1531n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1532 char *fp, int count)
1533{
1534 struct n_tty_data *ldata = tty->disc_data;
1535 char flag = TTY_NORMAL;
1536
1537 while (count--) {
1538 if (fp)
1539 flag = *fp++;
1540 if (likely(flag == TTY_NORMAL)) {
1541 unsigned char c = *cp++;
1542
1543 if (I_ISTRIP(tty))
1544 c &= 0x7f;
1545 if (I_IUCLC(tty) && L_IEXTEN(tty))
1546 c = tolower(c);
1547 if (L_EXTPROC(tty)) {
1548 put_tty_queue(c, ldata);
1549 continue;
1550 }
1551 if (!test_bit(c, ldata->char_map))
1552 n_tty_receive_char_inline(tty, c);
1553 else if (n_tty_receive_char_special(tty, c) && count) {
1554 if (fp)
1555 flag = *fp++;
1556 n_tty_receive_char_lnext(tty, *cp++, flag);
1557 count--;
1558 }
1559 } else
1560 n_tty_receive_char_flagged(tty, *cp++, flag);
1561 }
1562}
1563
1564static void
1565n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1566 char *fp, int count)
1567{
1568 struct n_tty_data *ldata = tty->disc_data;
1569 char flag = TTY_NORMAL;
1570
1571 while (count--) {
1572 if (fp)
1573 flag = *fp++;
1574 if (likely(flag == TTY_NORMAL)) {
1575 unsigned char c = *cp++;
1576
1577 if (!test_bit(c, ldata->char_map))
1578 n_tty_receive_char_fast(tty, c);
1579 else if (n_tty_receive_char_special(tty, c) && count) {
1580 if (fp)
1581 flag = *fp++;
1582 n_tty_receive_char_lnext(tty, *cp++, flag);
1583 count--;
1584 }
1585 } else
1586 n_tty_receive_char_flagged(tty, *cp++, flag);
1587 }
1588}
1589
1590static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1591 char *fp, int count)
1592{
1593 struct n_tty_data *ldata = tty->disc_data;
1594 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1595
1596 if (ldata->real_raw)
1597 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1598 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1599 n_tty_receive_buf_raw(tty, cp, fp, count);
1600 else if (tty->closing && !L_EXTPROC(tty))
1601 n_tty_receive_buf_closing(tty, cp, fp, count);
1602 else {
1603 if (ldata->lnext) {
1604 char flag = TTY_NORMAL;
1605
1606 if (fp)
1607 flag = *fp++;
1608 n_tty_receive_char_lnext(tty, *cp++, flag);
1609 count--;
1610 }
1611
1612 if (!preops && !I_PARMRK(tty))
1613 n_tty_receive_buf_fast(tty, cp, fp, count);
1614 else
1615 n_tty_receive_buf_standard(tty, cp, fp, count);
1616
1617 flush_echoes(tty);
1618 if (tty->ops->flush_chars)
1619 tty->ops->flush_chars(tty);
1620 }
1621
1622 if (ldata->icanon && !L_EXTPROC(tty))
1623 return;
1624
1625 /* publish read_head to consumer */
1626 smp_store_release(&ldata->commit_head, ldata->read_head);
1627
1628 if (read_cnt(ldata)) {
1629 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1630 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1631 }
1632}
1633
1634/**
1635 * n_tty_receive_buf_common - process input
1636 * @tty: device to receive input
1637 * @cp: input chars
1638 * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
1639 * @count: number of input chars in @cp
1640 *
1641 * Called by the terminal driver when a block of characters has
1642 * been received. This function must be called from soft contexts
1643 * not from interrupt context. The driver is responsible for making
1644 * calls one at a time and in order (or using flush_to_ldisc)
1645 *
1646 * Returns the # of input chars from @cp which were processed.
1647 *
1648 * In canonical mode, the maximum line length is 4096 chars (including
1649 * the line termination char); lines longer than 4096 chars are
1650 * truncated. After 4095 chars, input data is still processed but
1651 * not stored. Overflow processing ensures the tty can always
1652 * receive more input until at least one line can be read.
1653 *
1654 * In non-canonical mode, the read buffer will only accept 4095 chars;
1655 * this provides the necessary space for a newline char if the input
1656 * mode is switched to canonical.
1657 *
1658 * Note it is possible for the read buffer to _contain_ 4096 chars
1659 * in non-canonical mode: the read buffer could already contain the
1660 * maximum canon line of 4096 chars when the mode is switched to
1661 * non-canonical.
1662 *
1663 * n_tty_receive_buf()/producer path:
1664 * claims non-exclusive termios_rwsem
1665 * publishes commit_head or canon_head
1666 */
1667static int
1668n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1669 char *fp, int count, int flow)
1670{
1671 struct n_tty_data *ldata = tty->disc_data;
1672 int room, n, rcvd = 0, overflow;
1673
1674 down_read(&tty->termios_rwsem);
1675
1676 while (1) {
1677 /*
1678 * When PARMRK is set, each input char may take up to 3 chars
1679 * in the read buf; reduce the buffer space avail by 3x
1680 *
1681 * If we are doing input canonicalization, and there are no
1682 * pending newlines, let characters through without limit, so
1683 * that erase characters will be handled. Other excess
1684 * characters will be beeped.
1685 *
1686 * paired with store in *_copy_from_read_buf() -- guarantees
1687 * the consumer has loaded the data in read_buf up to the new
1688 * read_tail (so this producer will not overwrite unread data)
1689 */
1690 size_t tail = smp_load_acquire(&ldata->read_tail);
1691
1692 room = N_TTY_BUF_SIZE - (ldata->read_head - tail);
1693 if (I_PARMRK(tty))
1694 room = (room + 2) / 3;
1695 room--;
1696 if (room <= 0) {
1697 overflow = ldata->icanon && ldata->canon_head == tail;
1698 if (overflow && room < 0)
1699 ldata->read_head--;
1700 room = overflow;
1701 ldata->no_room = flow && !room;
1702 } else
1703 overflow = 0;
1704
1705 n = min(count, room);
1706 if (!n)
1707 break;
1708
1709 /* ignore parity errors if handling overflow */
1710 if (!overflow || !fp || *fp != TTY_PARITY)
1711 __receive_buf(tty, cp, fp, n);
1712
1713 cp += n;
1714 if (fp)
1715 fp += n;
1716 count -= n;
1717 rcvd += n;
1718 }
1719
1720 tty->receive_room = room;
1721
1722 /* Unthrottle if handling overflow on pty */
1723 if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
1724 if (overflow) {
1725 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
1726 tty_unthrottle_safe(tty);
1727 __tty_set_flow_change(tty, 0);
1728 }
1729 } else
1730 n_tty_check_throttle(tty);
1731
1732 up_read(&tty->termios_rwsem);
1733
1734 return rcvd;
1735}
1736
1737static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1738 char *fp, int count)
1739{
1740 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1741}
1742
1743static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1744 char *fp, int count)
1745{
1746 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1747}
1748
1749/**
1750 * n_tty_set_termios - termios data changed
1751 * @tty: terminal
1752 * @old: previous data
1753 *
1754 * Called by the tty layer when the user changes termios flags so
1755 * that the line discipline can plan ahead. This function cannot sleep
1756 * and is protected from re-entry by the tty layer. The user is
1757 * guaranteed that this function will not be re-entered or in progress
1758 * when the ldisc is closed.
1759 *
1760 * Locking: Caller holds tty->termios_rwsem
1761 */
1762
1763static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1764{
1765 struct n_tty_data *ldata = tty->disc_data;
1766
1767 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1768 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1769 ldata->line_start = ldata->read_tail;
1770 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1771 ldata->canon_head = ldata->read_tail;
1772 ldata->push = 0;
1773 } else {
1774 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1775 ldata->read_flags);
1776 ldata->canon_head = ldata->read_head;
1777 ldata->push = 1;
1778 }
1779 ldata->commit_head = ldata->read_head;
1780 ldata->erasing = 0;
1781 ldata->lnext = 0;
1782 }
1783
1784 ldata->icanon = (L_ICANON(tty) != 0);
1785
1786 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1787 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1788 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1789 I_PARMRK(tty)) {
1790 bitmap_zero(ldata->char_map, 256);
1791
1792 if (I_IGNCR(tty) || I_ICRNL(tty))
1793 set_bit('\r', ldata->char_map);
1794 if (I_INLCR(tty))
1795 set_bit('\n', ldata->char_map);
1796
1797 if (L_ICANON(tty)) {
1798 set_bit(ERASE_CHAR(tty), ldata->char_map);
1799 set_bit(KILL_CHAR(tty), ldata->char_map);
1800 set_bit(EOF_CHAR(tty), ldata->char_map);
1801 set_bit('\n', ldata->char_map);
1802 set_bit(EOL_CHAR(tty), ldata->char_map);
1803 if (L_IEXTEN(tty)) {
1804 set_bit(WERASE_CHAR(tty), ldata->char_map);
1805 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1806 set_bit(EOL2_CHAR(tty), ldata->char_map);
1807 if (L_ECHO(tty))
1808 set_bit(REPRINT_CHAR(tty),
1809 ldata->char_map);
1810 }
1811 }
1812 if (I_IXON(tty)) {
1813 set_bit(START_CHAR(tty), ldata->char_map);
1814 set_bit(STOP_CHAR(tty), ldata->char_map);
1815 }
1816 if (L_ISIG(tty)) {
1817 set_bit(INTR_CHAR(tty), ldata->char_map);
1818 set_bit(QUIT_CHAR(tty), ldata->char_map);
1819 set_bit(SUSP_CHAR(tty), ldata->char_map);
1820 }
1821 clear_bit(__DISABLED_CHAR, ldata->char_map);
1822 ldata->raw = 0;
1823 ldata->real_raw = 0;
1824 } else {
1825 ldata->raw = 1;
1826 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1827 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1828 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1829 ldata->real_raw = 1;
1830 else
1831 ldata->real_raw = 0;
1832 }
1833 /*
1834 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1835 * been stopped by STOP_CHAR(tty) before it.
1836 */
1837 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1838 start_tty(tty);
1839 process_echoes(tty);
1840 }
1841
1842 /* The termios change make the tty ready for I/O */
1843 wake_up_interruptible(&tty->write_wait);
1844 wake_up_interruptible(&tty->read_wait);
1845}
1846
1847/**
1848 * n_tty_close - close the ldisc for this tty
1849 * @tty: device
1850 *
1851 * Called from the terminal layer when this line discipline is
1852 * being shut down, either because of a close or becsuse of a
1853 * discipline change. The function will not be called while other
1854 * ldisc methods are in progress.
1855 */
1856
1857static void n_tty_close(struct tty_struct *tty)
1858{
1859 struct n_tty_data *ldata = tty->disc_data;
1860
1861 if (tty->link)
1862 n_tty_packet_mode_flush(tty);
1863
1864 vfree(ldata);
1865 tty->disc_data = NULL;
1866}
1867
1868/**
1869 * n_tty_open - open an ldisc
1870 * @tty: terminal to open
1871 *
1872 * Called when this line discipline is being attached to the
1873 * terminal device. Can sleep. Called serialized so that no
1874 * other events will occur in parallel. No further open will occur
1875 * until a close.
1876 */
1877
1878static int n_tty_open(struct tty_struct *tty)
1879{
1880 struct n_tty_data *ldata;
1881
1882 /* Currently a malloc failure here can panic */
1883 ldata = vmalloc(sizeof(*ldata));
1884 if (!ldata)
1885 goto err;
1886
1887 ldata->overrun_time = jiffies;
1888 mutex_init(&ldata->atomic_read_lock);
1889 mutex_init(&ldata->output_lock);
1890
1891 tty->disc_data = ldata;
1892 reset_buffer_flags(tty->disc_data);
1893 ldata->column = 0;
1894 ldata->canon_column = 0;
1895 ldata->num_overrun = 0;
1896 ldata->no_room = 0;
1897 ldata->lnext = 0;
1898 tty->closing = 0;
1899 /* indicate buffer work may resume */
1900 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1901 n_tty_set_termios(tty, NULL);
1902 tty_unthrottle(tty);
1903
1904 return 0;
1905err:
1906 return -ENOMEM;
1907}
1908
1909static inline int input_available_p(struct tty_struct *tty, int poll)
1910{
1911 struct n_tty_data *ldata = tty->disc_data;
1912 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
1913
1914 if (ldata->icanon && !L_EXTPROC(tty))
1915 return ldata->canon_head != ldata->read_tail;
1916 else
1917 return ldata->commit_head - ldata->read_tail >= amt;
1918}
1919
1920/**
1921 * copy_from_read_buf - copy read data directly
1922 * @tty: terminal device
1923 * @b: user data
1924 * @nr: size of data
1925 *
1926 * Helper function to speed up n_tty_read. It is only called when
1927 * ICANON is off; it copies characters straight from the tty queue to
1928 * user space directly. It can be profitably called twice; once to
1929 * drain the space from the tail pointer to the (physical) end of the
1930 * buffer, and once to drain the space from the (physical) beginning of
1931 * the buffer to head pointer.
1932 *
1933 * Called under the ldata->atomic_read_lock sem
1934 *
1935 * n_tty_read()/consumer path:
1936 * caller holds non-exclusive termios_rwsem
1937 * read_tail published
1938 */
1939
1940static int copy_from_read_buf(struct tty_struct *tty,
1941 unsigned char __user **b,
1942 size_t *nr)
1943
1944{
1945 struct n_tty_data *ldata = tty->disc_data;
1946 int retval;
1947 size_t n;
1948 bool is_eof;
1949 size_t head = smp_load_acquire(&ldata->commit_head);
1950 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1951
1952 retval = 0;
1953 n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail);
1954 n = min(*nr, n);
1955 if (n) {
1956 const unsigned char *from = read_buf_addr(ldata, tail);
1957 retval = copy_to_user(*b, from, n);
1958 n -= retval;
1959 is_eof = n == 1 && *from == EOF_CHAR(tty);
1960 tty_audit_add_data(tty, from, n);
1961 smp_store_release(&ldata->read_tail, ldata->read_tail + n);
1962 /* Turn single EOF into zero-length read */
1963 if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
1964 (head == ldata->read_tail))
1965 n = 0;
1966 *b += n;
1967 *nr -= n;
1968 }
1969 return retval;
1970}
1971
1972/**
1973 * canon_copy_from_read_buf - copy read data in canonical mode
1974 * @tty: terminal device
1975 * @b: user data
1976 * @nr: size of data
1977 *
1978 * Helper function for n_tty_read. It is only called when ICANON is on;
1979 * it copies one line of input up to and including the line-delimiting
1980 * character into the user-space buffer.
1981 *
1982 * NB: When termios is changed from non-canonical to canonical mode and
1983 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1984 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1985 * This causes data already processed as input to be immediately available
1986 * as input although a newline has not been received.
1987 *
1988 * Called under the atomic_read_lock mutex
1989 *
1990 * n_tty_read()/consumer path:
1991 * caller holds non-exclusive termios_rwsem
1992 * read_tail published
1993 */
1994
1995static int canon_copy_from_read_buf(struct tty_struct *tty,
1996 unsigned char __user **b,
1997 size_t *nr)
1998{
1999 struct n_tty_data *ldata = tty->disc_data;
2000 size_t n, size, more, c;
2001 size_t eol;
2002 size_t tail;
2003 int ret, found = 0;
2004
2005 /* N.B. avoid overrun if nr == 0 */
2006 if (!*nr)
2007 return 0;
2008
2009 n = min(*nr + 1, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
2010
2011 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
2012 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
2013
2014 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2015 __func__, *nr, tail, n, size);
2016
2017 eol = find_next_bit(ldata->read_flags, size, tail);
2018 more = n - (size - tail);
2019 if (eol == N_TTY_BUF_SIZE && more) {
2020 /* scan wrapped without finding set bit */
2021 eol = find_next_bit(ldata->read_flags, more, 0);
2022 found = eol != more;
2023 } else
2024 found = eol != size;
2025
2026 n = eol - tail;
2027 if (n > N_TTY_BUF_SIZE)
2028 n += N_TTY_BUF_SIZE;
2029 c = n + found;
2030
2031 if (!found || read_buf(ldata, eol) != __DISABLED_CHAR) {
2032 c = min(*nr, c);
2033 n = c;
2034 }
2035
2036 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu tail:%zu more:%zu\n",
2037 __func__, eol, found, n, c, tail, more);
2038
2039 ret = tty_copy_to_user(tty, *b, tail, n);
2040 if (ret)
2041 return -EFAULT;
2042 *b += n;
2043 *nr -= n;
2044
2045 if (found)
2046 clear_bit(eol, ldata->read_flags);
2047 smp_store_release(&ldata->read_tail, ldata->read_tail + c);
2048
2049 if (found) {
2050 if (!ldata->push)
2051 ldata->line_start = ldata->read_tail;
2052 else
2053 ldata->push = 0;
2054 tty_audit_push();
2055 }
2056 return 0;
2057}
2058
2059extern ssize_t redirected_tty_write(struct file *, const char __user *,
2060 size_t, loff_t *);
2061
2062/**
2063 * job_control - check job control
2064 * @tty: tty
2065 * @file: file handle
2066 *
2067 * Perform job control management checks on this file/tty descriptor
2068 * and if appropriate send any needed signals and return a negative
2069 * error code if action should be taken.
2070 *
2071 * Locking: redirected write test is safe
2072 * current->signal->tty check is safe
2073 * ctrl_lock to safely reference tty->pgrp
2074 */
2075
2076static int job_control(struct tty_struct *tty, struct file *file)
2077{
2078 /* Job control check -- must be done at start and after
2079 every sleep (POSIX.1 7.1.1.4). */
2080 /* NOTE: not yet done after every sleep pending a thorough
2081 check of the logic of this change. -- jlc */
2082 /* don't stop on /dev/console */
2083 if (file->f_op->write == redirected_tty_write)
2084 return 0;
2085
2086 return __tty_check_change(tty, SIGTTIN);
2087}
2088
2089
2090/**
2091 * n_tty_read - read function for tty
2092 * @tty: tty device
2093 * @file: file object
2094 * @buf: userspace buffer pointer
2095 * @nr: size of I/O
2096 *
2097 * Perform reads for the line discipline. We are guaranteed that the
2098 * line discipline will not be closed under us but we may get multiple
2099 * parallel readers and must handle this ourselves. We may also get
2100 * a hangup. Always called in user context, may sleep.
2101 *
2102 * This code must be sure never to sleep through a hangup.
2103 *
2104 * n_tty_read()/consumer path:
2105 * claims non-exclusive termios_rwsem
2106 * publishes read_tail
2107 */
2108
2109static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2110 unsigned char __user *buf, size_t nr)
2111{
2112 struct n_tty_data *ldata = tty->disc_data;
2113 unsigned char __user *b = buf;
2114 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2115 int c;
2116 int minimum, time;
2117 ssize_t retval = 0;
2118 long timeout;
2119 int packet;
2120 size_t tail;
2121
2122 c = job_control(tty, file);
2123 if (c < 0)
2124 return c;
2125
2126 /*
2127 * Internal serialization of reads.
2128 */
2129 if (file->f_flags & O_NONBLOCK) {
2130 if (!mutex_trylock(&ldata->atomic_read_lock))
2131 return -EAGAIN;
2132 } else {
2133 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2134 return -ERESTARTSYS;
2135 }
2136
2137 down_read(&tty->termios_rwsem);
2138
2139 minimum = time = 0;
2140 timeout = MAX_SCHEDULE_TIMEOUT;
2141 if (!ldata->icanon) {
2142 minimum = MIN_CHAR(tty);
2143 if (minimum) {
2144 time = (HZ / 10) * TIME_CHAR(tty);
2145 } else {
2146 timeout = (HZ / 10) * TIME_CHAR(tty);
2147 minimum = 1;
2148 }
2149 }
2150
2151 packet = tty->packet;
2152 tail = ldata->read_tail;
2153
2154 add_wait_queue(&tty->read_wait, &wait);
2155 while (nr) {
2156 /* First test for status change. */
2157 if (packet && tty->link->ctrl_status) {
2158 unsigned char cs;
2159 if (b != buf)
2160 break;
2161 spin_lock_irq(&tty->link->ctrl_lock);
2162 cs = tty->link->ctrl_status;
2163 tty->link->ctrl_status = 0;
2164 spin_unlock_irq(&tty->link->ctrl_lock);
2165 if (put_user(cs, b)) {
2166 retval = -EFAULT;
2167 break;
2168 }
2169 b++;
2170 nr--;
2171 break;
2172 }
2173
2174 if (!input_available_p(tty, 0)) {
2175 up_read(&tty->termios_rwsem);
2176 tty_buffer_flush_work(tty->port);
2177 down_read(&tty->termios_rwsem);
2178 if (!input_available_p(tty, 0)) {
2179 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2180 retval = -EIO;
2181 break;
2182 }
2183 if (tty_hung_up_p(file))
2184 break;
2185 if (!timeout)
2186 break;
2187 if (file->f_flags & O_NONBLOCK) {
2188 retval = -EAGAIN;
2189 break;
2190 }
2191 if (signal_pending(current)) {
2192 retval = -ERESTARTSYS;
2193 break;
2194 }
2195 up_read(&tty->termios_rwsem);
2196
2197 timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
2198 timeout);
2199
2200 down_read(&tty->termios_rwsem);
2201 continue;
2202 }
2203 }
2204
2205 if (ldata->icanon && !L_EXTPROC(tty)) {
2206 retval = canon_copy_from_read_buf(tty, &b, &nr);
2207 if (retval)
2208 break;
2209 } else {
2210 int uncopied;
2211
2212 /* Deal with packet mode. */
2213 if (packet && b == buf) {
2214 if (put_user(TIOCPKT_DATA, b)) {
2215 retval = -EFAULT;
2216 break;
2217 }
2218 b++;
2219 nr--;
2220 }
2221
2222 uncopied = copy_from_read_buf(tty, &b, &nr);
2223 uncopied += copy_from_read_buf(tty, &b, &nr);
2224 if (uncopied) {
2225 retval = -EFAULT;
2226 break;
2227 }
2228 }
2229
2230 n_tty_check_unthrottle(tty);
2231
2232 if (b - buf >= minimum)
2233 break;
2234 if (time)
2235 timeout = time;
2236 }
2237 if (tail != ldata->read_tail)
2238 n_tty_kick_worker(tty);
2239 up_read(&tty->termios_rwsem);
2240
2241 remove_wait_queue(&tty->read_wait, &wait);
2242 mutex_unlock(&ldata->atomic_read_lock);
2243
2244 if (b - buf)
2245 retval = b - buf;
2246
2247 return retval;
2248}
2249
2250/**
2251 * n_tty_write - write function for tty
2252 * @tty: tty device
2253 * @file: file object
2254 * @buf: userspace buffer pointer
2255 * @nr: size of I/O
2256 *
2257 * Write function of the terminal device. This is serialized with
2258 * respect to other write callers but not to termios changes, reads
2259 * and other such events. Since the receive code will echo characters,
2260 * thus calling driver write methods, the output_lock is used in
2261 * the output processing functions called here as well as in the
2262 * echo processing function to protect the column state and space
2263 * left in the buffer.
2264 *
2265 * This code must be sure never to sleep through a hangup.
2266 *
2267 * Locking: output_lock to protect column state and space left
2268 * (note that the process_output*() functions take this
2269 * lock themselves)
2270 */
2271
2272static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2273 const unsigned char *buf, size_t nr)
2274{
2275 const unsigned char *b = buf;
2276 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2277 int c;
2278 ssize_t retval = 0;
2279
2280 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2281 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2282 retval = tty_check_change(tty);
2283 if (retval)
2284 return retval;
2285 }
2286
2287 down_read(&tty->termios_rwsem);
2288
2289 /* Write out any echoed characters that are still pending */
2290 process_echoes(tty);
2291
2292 add_wait_queue(&tty->write_wait, &wait);
2293 while (1) {
2294 if (signal_pending(current)) {
2295 retval = -ERESTARTSYS;
2296 break;
2297 }
2298 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2299 retval = -EIO;
2300 break;
2301 }
2302 if (O_OPOST(tty)) {
2303 while (nr > 0) {
2304 ssize_t num = process_output_block(tty, b, nr);
2305 if (num < 0) {
2306 if (num == -EAGAIN)
2307 break;
2308 retval = num;
2309 goto break_out;
2310 }
2311 b += num;
2312 nr -= num;
2313 if (nr == 0)
2314 break;
2315 c = *b;
2316 if (process_output(c, tty) < 0)
2317 break;
2318 b++; nr--;
2319 }
2320 if (tty->ops->flush_chars)
2321 tty->ops->flush_chars(tty);
2322 } else {
2323 struct n_tty_data *ldata = tty->disc_data;
2324
2325 while (nr > 0) {
2326 mutex_lock(&ldata->output_lock);
2327 c = tty->ops->write(tty, b, nr);
2328 mutex_unlock(&ldata->output_lock);
2329 if (c < 0) {
2330 retval = c;
2331 goto break_out;
2332 }
2333 if (!c)
2334 break;
2335 b += c;
2336 nr -= c;
2337 }
2338 }
2339 if (!nr)
2340 break;
2341 if (file->f_flags & O_NONBLOCK) {
2342 retval = -EAGAIN;
2343 break;
2344 }
2345 up_read(&tty->termios_rwsem);
2346
2347 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
2348
2349 down_read(&tty->termios_rwsem);
2350 }
2351break_out:
2352 remove_wait_queue(&tty->write_wait, &wait);
2353 if (nr && tty->fasync)
2354 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2355 up_read(&tty->termios_rwsem);
2356 return (b - buf) ? b - buf : retval;
2357}
2358
2359/**
2360 * n_tty_poll - poll method for N_TTY
2361 * @tty: terminal device
2362 * @file: file accessing it
2363 * @wait: poll table
2364 *
2365 * Called when the line discipline is asked to poll() for data or
2366 * for special events. This code is not serialized with respect to
2367 * other events save open/close.
2368 *
2369 * This code must be sure never to sleep through a hangup.
2370 * Called without the kernel lock held - fine
2371 */
2372
2373static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2374 poll_table *wait)
2375{
2376 unsigned int mask = 0;
2377
2378 poll_wait(file, &tty->read_wait, wait);
2379 poll_wait(file, &tty->write_wait, wait);
2380 if (input_available_p(tty, 1))
2381 mask |= POLLIN | POLLRDNORM;
2382 else {
2383 tty_buffer_flush_work(tty->port);
2384 if (input_available_p(tty, 1))
2385 mask |= POLLIN | POLLRDNORM;
2386 }
2387 if (tty->packet && tty->link->ctrl_status)
2388 mask |= POLLPRI | POLLIN | POLLRDNORM;
2389 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2390 mask |= POLLHUP;
2391 if (tty_hung_up_p(file))
2392 mask |= POLLHUP;
2393 if (tty->ops->write && !tty_is_writelocked(tty) &&
2394 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2395 tty_write_room(tty) > 0)
2396 mask |= POLLOUT | POLLWRNORM;
2397 return mask;
2398}
2399
2400static unsigned long inq_canon(struct n_tty_data *ldata)
2401{
2402 size_t nr, head, tail;
2403
2404 if (ldata->canon_head == ldata->read_tail)
2405 return 0;
2406 head = ldata->canon_head;
2407 tail = ldata->read_tail;
2408 nr = head - tail;
2409 /* Skip EOF-chars.. */
2410 while (head != tail) {
2411 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2412 read_buf(ldata, tail) == __DISABLED_CHAR)
2413 nr--;
2414 tail++;
2415 }
2416 return nr;
2417}
2418
2419static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2420 unsigned int cmd, unsigned long arg)
2421{
2422 struct n_tty_data *ldata = tty->disc_data;
2423 int retval;
2424
2425 switch (cmd) {
2426 case TIOCOUTQ:
2427 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2428 case TIOCINQ:
2429 down_write(&tty->termios_rwsem);
2430 if (L_ICANON(tty))
2431 retval = inq_canon(ldata);
2432 else
2433 retval = read_cnt(ldata);
2434 up_write(&tty->termios_rwsem);
2435 return put_user(retval, (unsigned int __user *) arg);
2436 default:
2437 return n_tty_ioctl_helper(tty, file, cmd, arg);
2438 }
2439}
2440
2441static struct tty_ldisc_ops n_tty_ops = {
2442 .magic = TTY_LDISC_MAGIC,
2443 .name = "n_tty",
2444 .open = n_tty_open,
2445 .close = n_tty_close,
2446 .flush_buffer = n_tty_flush_buffer,
2447 .read = n_tty_read,
2448 .write = n_tty_write,
2449 .ioctl = n_tty_ioctl,
2450 .set_termios = n_tty_set_termios,
2451 .poll = n_tty_poll,
2452 .receive_buf = n_tty_receive_buf,
2453 .write_wakeup = n_tty_write_wakeup,
2454 .receive_buf2 = n_tty_receive_buf2,
2455};
2456
2457/**
2458 * n_tty_inherit_ops - inherit N_TTY methods
2459 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2460 *
2461 * Enables a 'subclass' line discipline to 'inherit' N_TTY methods.
2462 */
2463
2464void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2465{
2466 *ops = n_tty_ops;
2467 ops->owner = NULL;
2468 ops->refcount = ops->flags = 0;
2469}
2470EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
2471
2472void __init n_tty_init(void)
2473{
2474 tty_register_ldisc(N_TTY, &n_tty_ops);
2475}