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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 canon_head;
94 size_t echo_head;
95 size_t echo_commit;
96 size_t echo_mark;
97 DECLARE_BITMAP(char_map, 256);
98
99 /* private to n_tty_receive_overrun (single-threaded) */
100 unsigned long overrun_time;
101 int num_overrun;
102
103 /* non-atomic */
104 bool no_room;
105
106 /* must hold exclusive termios_rwsem to reset these */
107 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
108 unsigned char push:1;
109
110 /* shared by producer and consumer */
111 char read_buf[N_TTY_BUF_SIZE];
112 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
113 unsigned char echo_buf[N_TTY_BUF_SIZE];
114
115 int minimum_to_wake;
116
117 /* consumer-published */
118 size_t read_tail;
119 size_t line_start;
120
121 /* protected by output lock */
122 unsigned int column;
123 unsigned int canon_column;
124 size_t echo_tail;
125
126 struct mutex atomic_read_lock;
127 struct mutex output_lock;
128};
129
130static inline size_t read_cnt(struct n_tty_data *ldata)
131{
132 return ldata->read_head - ldata->read_tail;
133}
134
135static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
136{
137 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
138}
139
140static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
141{
142 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
143}
144
145static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
146{
147 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
148}
149
150static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
151{
152 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
153}
154
155static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
156 unsigned char __user *ptr)
157{
158 struct n_tty_data *ldata = tty->disc_data;
159
160 tty_audit_add_data(tty, &x, 1, ldata->icanon);
161 return put_user(x, ptr);
162}
163
164static int receive_room(struct tty_struct *tty)
165{
166 struct n_tty_data *ldata = tty->disc_data;
167 int left;
168
169 if (I_PARMRK(tty)) {
170 /* Multiply read_cnt by 3, since each byte might take up to
171 * three times as many spaces when PARMRK is set (depending on
172 * its flags, e.g. parity error). */
173 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
174 } else
175 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
176
177 /*
178 * If we are doing input canonicalization, and there are no
179 * pending newlines, let characters through without limit, so
180 * that erase characters will be handled. Other excess
181 * characters will be beeped.
182 */
183 if (left <= 0)
184 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
185
186 return left;
187}
188
189/**
190 * n_tty_set_room - receive space
191 * @tty: terminal
192 *
193 * Re-schedules the flip buffer work if space just became available.
194 *
195 * Caller holds exclusive termios_rwsem
196 * or
197 * n_tty_read()/consumer path:
198 * holds non-exclusive termios_rwsem
199 */
200
201static void n_tty_set_room(struct tty_struct *tty)
202{
203 struct n_tty_data *ldata = tty->disc_data;
204
205 /* Did this open up the receive buffer? We may need to flip */
206 if (unlikely(ldata->no_room) && receive_room(tty)) {
207 ldata->no_room = 0;
208
209 WARN_RATELIMIT(tty->port->itty == NULL,
210 "scheduling with invalid itty\n");
211 /* see if ldisc has been killed - if so, this means that
212 * even though the ldisc has been halted and ->buf.work
213 * cancelled, ->buf.work is about to be rescheduled
214 */
215 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
216 "scheduling buffer work for halted ldisc\n");
217 queue_work(system_unbound_wq, &tty->port->buf.work);
218 }
219}
220
221static ssize_t chars_in_buffer(struct tty_struct *tty)
222{
223 struct n_tty_data *ldata = tty->disc_data;
224 ssize_t n = 0;
225
226 if (!ldata->icanon)
227 n = read_cnt(ldata);
228 else
229 n = ldata->canon_head - ldata->read_tail;
230 return n;
231}
232
233/**
234 * n_tty_write_wakeup - asynchronous I/O notifier
235 * @tty: tty device
236 *
237 * Required for the ptys, serial driver etc. since processes
238 * that attach themselves to the master and rely on ASYNC
239 * IO must be woken up
240 */
241
242static void n_tty_write_wakeup(struct tty_struct *tty)
243{
244 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
245 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
246}
247
248static void n_tty_check_throttle(struct tty_struct *tty)
249{
250 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
251 return;
252 /*
253 * Check the remaining room for the input canonicalization
254 * mode. We don't want to throttle the driver if we're in
255 * canonical mode and don't have a newline yet!
256 */
257 while (1) {
258 int throttled;
259 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
260 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
261 break;
262 throttled = tty_throttle_safe(tty);
263 if (!throttled)
264 break;
265 }
266 __tty_set_flow_change(tty, 0);
267}
268
269static void n_tty_check_unthrottle(struct tty_struct *tty)
270{
271 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
272 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
273 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
274 return;
275 if (!tty->count)
276 return;
277 n_tty_set_room(tty);
278 n_tty_write_wakeup(tty->link);
279 if (waitqueue_active(&tty->link->write_wait))
280 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
281 return;
282 }
283
284 /* If there is enough space in the read buffer now, let the
285 * low-level driver know. We use chars_in_buffer() to
286 * check the buffer, as it now knows about canonical mode.
287 * Otherwise, if the driver is throttled and the line is
288 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
289 * we won't get any more characters.
290 */
291
292 while (1) {
293 int unthrottled;
294 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
295 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
296 break;
297 if (!tty->count)
298 break;
299 n_tty_set_room(tty);
300 unthrottled = tty_unthrottle_safe(tty);
301 if (!unthrottled)
302 break;
303 }
304 __tty_set_flow_change(tty, 0);
305}
306
307/**
308 * put_tty_queue - add character to tty
309 * @c: character
310 * @ldata: n_tty data
311 *
312 * Add a character to the tty read_buf queue.
313 *
314 * n_tty_receive_buf()/producer path:
315 * caller holds non-exclusive termios_rwsem
316 * modifies read_head
317 *
318 * read_head is only considered 'published' if canonical mode is
319 * not active.
320 */
321
322static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
323{
324 *read_buf_addr(ldata, ldata->read_head++) = c;
325}
326
327/**
328 * reset_buffer_flags - reset buffer state
329 * @tty: terminal to reset
330 *
331 * Reset the read buffer counters and clear the flags.
332 * Called from n_tty_open() and n_tty_flush_buffer().
333 *
334 * Locking: caller holds exclusive termios_rwsem
335 * (or locking is not required)
336 */
337
338static void reset_buffer_flags(struct n_tty_data *ldata)
339{
340 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
341 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
342 ldata->echo_mark = 0;
343 ldata->line_start = 0;
344
345 ldata->erasing = 0;
346 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
347 ldata->push = 0;
348}
349
350static void n_tty_packet_mode_flush(struct tty_struct *tty)
351{
352 unsigned long flags;
353
354 spin_lock_irqsave(&tty->ctrl_lock, flags);
355 if (tty->link->packet) {
356 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
357 if (waitqueue_active(&tty->link->read_wait))
358 wake_up_interruptible(&tty->link->read_wait);
359 }
360 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
361}
362
363/**
364 * n_tty_flush_buffer - clean input queue
365 * @tty: terminal device
366 *
367 * Flush the input buffer. Called when the tty layer wants the
368 * buffer flushed (eg at hangup) or when the N_TTY line discipline
369 * internally has to clean the pending queue (for example some signals).
370 *
371 * Holds termios_rwsem to exclude producer/consumer while
372 * buffer indices are reset.
373 *
374 * Locking: ctrl_lock, exclusive termios_rwsem
375 */
376
377static void n_tty_flush_buffer(struct tty_struct *tty)
378{
379 down_write(&tty->termios_rwsem);
380 reset_buffer_flags(tty->disc_data);
381 n_tty_set_room(tty);
382
383 if (tty->link)
384 n_tty_packet_mode_flush(tty);
385 up_write(&tty->termios_rwsem);
386}
387
388/**
389 * n_tty_chars_in_buffer - report available bytes
390 * @tty: tty device
391 *
392 * Report the number of characters buffered to be delivered to user
393 * at this instant in time.
394 *
395 * Locking: exclusive termios_rwsem
396 */
397
398static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
399{
400 ssize_t n;
401
402 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
403
404 down_write(&tty->termios_rwsem);
405 n = chars_in_buffer(tty);
406 up_write(&tty->termios_rwsem);
407 return n;
408}
409
410/**
411 * is_utf8_continuation - utf8 multibyte check
412 * @c: byte to check
413 *
414 * Returns true if the utf8 character 'c' is a multibyte continuation
415 * character. We use this to correctly compute the on screen size
416 * of the character when printing
417 */
418
419static inline int is_utf8_continuation(unsigned char c)
420{
421 return (c & 0xc0) == 0x80;
422}
423
424/**
425 * is_continuation - multibyte check
426 * @c: byte to check
427 *
428 * Returns true if the utf8 character 'c' is a multibyte continuation
429 * character and the terminal is in unicode mode.
430 */
431
432static inline int is_continuation(unsigned char c, struct tty_struct *tty)
433{
434 return I_IUTF8(tty) && is_utf8_continuation(c);
435}
436
437/**
438 * do_output_char - output one character
439 * @c: character (or partial unicode symbol)
440 * @tty: terminal device
441 * @space: space available in tty driver write buffer
442 *
443 * This is a helper function that handles one output character
444 * (including special characters like TAB, CR, LF, etc.),
445 * doing OPOST processing and putting the results in the
446 * tty driver's write buffer.
447 *
448 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
449 * and NLDLY. They simply aren't relevant in the world today.
450 * If you ever need them, add them here.
451 *
452 * Returns the number of bytes of buffer space used or -1 if
453 * no space left.
454 *
455 * Locking: should be called under the output_lock to protect
456 * the column state and space left in the buffer
457 */
458
459static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
460{
461 struct n_tty_data *ldata = tty->disc_data;
462 int spaces;
463
464 if (!space)
465 return -1;
466
467 switch (c) {
468 case '\n':
469 if (O_ONLRET(tty))
470 ldata->column = 0;
471 if (O_ONLCR(tty)) {
472 if (space < 2)
473 return -1;
474 ldata->canon_column = ldata->column = 0;
475 tty->ops->write(tty, "\r\n", 2);
476 return 2;
477 }
478 ldata->canon_column = ldata->column;
479 break;
480 case '\r':
481 if (O_ONOCR(tty) && ldata->column == 0)
482 return 0;
483 if (O_OCRNL(tty)) {
484 c = '\n';
485 if (O_ONLRET(tty))
486 ldata->canon_column = ldata->column = 0;
487 break;
488 }
489 ldata->canon_column = ldata->column = 0;
490 break;
491 case '\t':
492 spaces = 8 - (ldata->column & 7);
493 if (O_TABDLY(tty) == XTABS) {
494 if (space < spaces)
495 return -1;
496 ldata->column += spaces;
497 tty->ops->write(tty, " ", spaces);
498 return spaces;
499 }
500 ldata->column += spaces;
501 break;
502 case '\b':
503 if (ldata->column > 0)
504 ldata->column--;
505 break;
506 default:
507 if (!iscntrl(c)) {
508 if (O_OLCUC(tty))
509 c = toupper(c);
510 if (!is_continuation(c, tty))
511 ldata->column++;
512 }
513 break;
514 }
515
516 tty_put_char(tty, c);
517 return 1;
518}
519
520/**
521 * process_output - output post processor
522 * @c: character (or partial unicode symbol)
523 * @tty: terminal device
524 *
525 * Output one character with OPOST processing.
526 * Returns -1 when the output device is full and the character
527 * must be retried.
528 *
529 * Locking: output_lock to protect column state and space left
530 * (also, this is called from n_tty_write under the
531 * tty layer write lock)
532 */
533
534static int process_output(unsigned char c, struct tty_struct *tty)
535{
536 struct n_tty_data *ldata = tty->disc_data;
537 int space, retval;
538
539 mutex_lock(&ldata->output_lock);
540
541 space = tty_write_room(tty);
542 retval = do_output_char(c, tty, space);
543
544 mutex_unlock(&ldata->output_lock);
545 if (retval < 0)
546 return -1;
547 else
548 return 0;
549}
550
551/**
552 * process_output_block - block post processor
553 * @tty: terminal device
554 * @buf: character buffer
555 * @nr: number of bytes to output
556 *
557 * Output a block of characters with OPOST processing.
558 * Returns the number of characters output.
559 *
560 * This path is used to speed up block console writes, among other
561 * things when processing blocks of output data. It handles only
562 * the simple cases normally found and helps to generate blocks of
563 * symbols for the console driver and thus improve performance.
564 *
565 * Locking: output_lock to protect column state and space left
566 * (also, this is called from n_tty_write under the
567 * tty layer write lock)
568 */
569
570static ssize_t process_output_block(struct tty_struct *tty,
571 const unsigned char *buf, unsigned int nr)
572{
573 struct n_tty_data *ldata = tty->disc_data;
574 int space;
575 int i;
576 const unsigned char *cp;
577
578 mutex_lock(&ldata->output_lock);
579
580 space = tty_write_room(tty);
581 if (!space) {
582 mutex_unlock(&ldata->output_lock);
583 return 0;
584 }
585 if (nr > space)
586 nr = space;
587
588 for (i = 0, cp = buf; i < nr; i++, cp++) {
589 unsigned char c = *cp;
590
591 switch (c) {
592 case '\n':
593 if (O_ONLRET(tty))
594 ldata->column = 0;
595 if (O_ONLCR(tty))
596 goto break_out;
597 ldata->canon_column = ldata->column;
598 break;
599 case '\r':
600 if (O_ONOCR(tty) && ldata->column == 0)
601 goto break_out;
602 if (O_OCRNL(tty))
603 goto break_out;
604 ldata->canon_column = ldata->column = 0;
605 break;
606 case '\t':
607 goto break_out;
608 case '\b':
609 if (ldata->column > 0)
610 ldata->column--;
611 break;
612 default:
613 if (!iscntrl(c)) {
614 if (O_OLCUC(tty))
615 goto break_out;
616 if (!is_continuation(c, tty))
617 ldata->column++;
618 }
619 break;
620 }
621 }
622break_out:
623 i = tty->ops->write(tty, buf, i);
624
625 mutex_unlock(&ldata->output_lock);
626 return i;
627}
628
629/**
630 * process_echoes - write pending echo characters
631 * @tty: terminal device
632 *
633 * Write previously buffered echo (and other ldisc-generated)
634 * characters to the tty.
635 *
636 * Characters generated by the ldisc (including echoes) need to
637 * be buffered because the driver's write buffer can fill during
638 * heavy program output. Echoing straight to the driver will
639 * often fail under these conditions, causing lost characters and
640 * resulting mismatches of ldisc state information.
641 *
642 * Since the ldisc state must represent the characters actually sent
643 * to the driver at the time of the write, operations like certain
644 * changes in column state are also saved in the buffer and executed
645 * here.
646 *
647 * A circular fifo buffer is used so that the most recent characters
648 * are prioritized. Also, when control characters are echoed with a
649 * prefixed "^", the pair is treated atomically and thus not separated.
650 *
651 * Locking: callers must hold output_lock
652 */
653
654static size_t __process_echoes(struct tty_struct *tty)
655{
656 struct n_tty_data *ldata = tty->disc_data;
657 int space, old_space;
658 size_t tail;
659 unsigned char c;
660
661 old_space = space = tty_write_room(tty);
662
663 tail = ldata->echo_tail;
664 while (ldata->echo_commit != tail) {
665 c = echo_buf(ldata, tail);
666 if (c == ECHO_OP_START) {
667 unsigned char op;
668 int no_space_left = 0;
669
670 /*
671 * If the buffer byte is the start of a multi-byte
672 * operation, get the next byte, which is either the
673 * op code or a control character value.
674 */
675 op = echo_buf(ldata, tail + 1);
676
677 switch (op) {
678 unsigned int num_chars, num_bs;
679
680 case ECHO_OP_ERASE_TAB:
681 num_chars = echo_buf(ldata, tail + 2);
682
683 /*
684 * Determine how many columns to go back
685 * in order to erase the tab.
686 * This depends on the number of columns
687 * used by other characters within the tab
688 * area. If this (modulo 8) count is from
689 * the start of input rather than from a
690 * previous tab, we offset by canon column.
691 * Otherwise, tab spacing is normal.
692 */
693 if (!(num_chars & 0x80))
694 num_chars += ldata->canon_column;
695 num_bs = 8 - (num_chars & 7);
696
697 if (num_bs > space) {
698 no_space_left = 1;
699 break;
700 }
701 space -= num_bs;
702 while (num_bs--) {
703 tty_put_char(tty, '\b');
704 if (ldata->column > 0)
705 ldata->column--;
706 }
707 tail += 3;
708 break;
709
710 case ECHO_OP_SET_CANON_COL:
711 ldata->canon_column = ldata->column;
712 tail += 2;
713 break;
714
715 case ECHO_OP_MOVE_BACK_COL:
716 if (ldata->column > 0)
717 ldata->column--;
718 tail += 2;
719 break;
720
721 case ECHO_OP_START:
722 /* This is an escaped echo op start code */
723 if (!space) {
724 no_space_left = 1;
725 break;
726 }
727 tty_put_char(tty, ECHO_OP_START);
728 ldata->column++;
729 space--;
730 tail += 2;
731 break;
732
733 default:
734 /*
735 * If the op is not a special byte code,
736 * it is a ctrl char tagged to be echoed
737 * as "^X" (where X is the letter
738 * representing the control char).
739 * Note that we must ensure there is
740 * enough space for the whole ctrl pair.
741 *
742 */
743 if (space < 2) {
744 no_space_left = 1;
745 break;
746 }
747 tty_put_char(tty, '^');
748 tty_put_char(tty, op ^ 0100);
749 ldata->column += 2;
750 space -= 2;
751 tail += 2;
752 }
753
754 if (no_space_left)
755 break;
756 } else {
757 if (O_OPOST(tty)) {
758 int retval = do_output_char(c, tty, space);
759 if (retval < 0)
760 break;
761 space -= retval;
762 } else {
763 if (!space)
764 break;
765 tty_put_char(tty, c);
766 space -= 1;
767 }
768 tail += 1;
769 }
770 }
771
772 /* If the echo buffer is nearly full (so that the possibility exists
773 * of echo overrun before the next commit), then discard enough
774 * data at the tail to prevent a subsequent overrun */
775 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
776 if (echo_buf(ldata, tail) == ECHO_OP_START) {
777 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
778 tail += 3;
779 else
780 tail += 2;
781 } else
782 tail++;
783 }
784
785 ldata->echo_tail = tail;
786 return old_space - space;
787}
788
789static void commit_echoes(struct tty_struct *tty)
790{
791 struct n_tty_data *ldata = tty->disc_data;
792 size_t nr, old, echoed;
793 size_t head;
794
795 head = ldata->echo_head;
796 ldata->echo_mark = head;
797 old = ldata->echo_commit - ldata->echo_tail;
798
799 /* Process committed echoes if the accumulated # of bytes
800 * is over the threshold (and try again each time another
801 * block is accumulated) */
802 nr = head - ldata->echo_tail;
803 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
804 return;
805
806 mutex_lock(&ldata->output_lock);
807 ldata->echo_commit = head;
808 echoed = __process_echoes(tty);
809 mutex_unlock(&ldata->output_lock);
810
811 if (echoed && tty->ops->flush_chars)
812 tty->ops->flush_chars(tty);
813}
814
815static void process_echoes(struct tty_struct *tty)
816{
817 struct n_tty_data *ldata = tty->disc_data;
818 size_t echoed;
819
820 if (ldata->echo_mark == ldata->echo_tail)
821 return;
822
823 mutex_lock(&ldata->output_lock);
824 ldata->echo_commit = ldata->echo_mark;
825 echoed = __process_echoes(tty);
826 mutex_unlock(&ldata->output_lock);
827
828 if (echoed && tty->ops->flush_chars)
829 tty->ops->flush_chars(tty);
830}
831
832/* NB: echo_mark and echo_head should be equivalent here */
833static void flush_echoes(struct tty_struct *tty)
834{
835 struct n_tty_data *ldata = tty->disc_data;
836
837 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
838 ldata->echo_commit == ldata->echo_head)
839 return;
840
841 mutex_lock(&ldata->output_lock);
842 ldata->echo_commit = ldata->echo_head;
843 __process_echoes(tty);
844 mutex_unlock(&ldata->output_lock);
845}
846
847/**
848 * add_echo_byte - add a byte to the echo buffer
849 * @c: unicode byte to echo
850 * @ldata: n_tty data
851 *
852 * Add a character or operation byte to the echo buffer.
853 */
854
855static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
856{
857 *echo_buf_addr(ldata, ldata->echo_head++) = c;
858}
859
860/**
861 * echo_move_back_col - add operation to move back a column
862 * @ldata: n_tty data
863 *
864 * Add an operation to the echo buffer to move back one column.
865 */
866
867static void echo_move_back_col(struct n_tty_data *ldata)
868{
869 add_echo_byte(ECHO_OP_START, ldata);
870 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
871}
872
873/**
874 * echo_set_canon_col - add operation to set the canon column
875 * @ldata: n_tty data
876 *
877 * Add an operation to the echo buffer to set the canon column
878 * to the current column.
879 */
880
881static void echo_set_canon_col(struct n_tty_data *ldata)
882{
883 add_echo_byte(ECHO_OP_START, ldata);
884 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
885}
886
887/**
888 * echo_erase_tab - add operation to erase a tab
889 * @num_chars: number of character columns already used
890 * @after_tab: true if num_chars starts after a previous tab
891 * @ldata: n_tty data
892 *
893 * Add an operation to the echo buffer to erase a tab.
894 *
895 * Called by the eraser function, which knows how many character
896 * columns have been used since either a previous tab or the start
897 * of input. This information will be used later, along with
898 * canon column (if applicable), to go back the correct number
899 * of columns.
900 */
901
902static void echo_erase_tab(unsigned int num_chars, int after_tab,
903 struct n_tty_data *ldata)
904{
905 add_echo_byte(ECHO_OP_START, ldata);
906 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
907
908 /* We only need to know this modulo 8 (tab spacing) */
909 num_chars &= 7;
910
911 /* Set the high bit as a flag if num_chars is after a previous tab */
912 if (after_tab)
913 num_chars |= 0x80;
914
915 add_echo_byte(num_chars, ldata);
916}
917
918/**
919 * echo_char_raw - echo a character raw
920 * @c: unicode byte to echo
921 * @tty: terminal device
922 *
923 * Echo user input back onto the screen. This must be called only when
924 * L_ECHO(tty) is true. Called from the driver receive_buf path.
925 *
926 * This variant does not treat control characters specially.
927 */
928
929static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
930{
931 if (c == ECHO_OP_START) {
932 add_echo_byte(ECHO_OP_START, ldata);
933 add_echo_byte(ECHO_OP_START, ldata);
934 } else {
935 add_echo_byte(c, ldata);
936 }
937}
938
939/**
940 * echo_char - echo a character
941 * @c: unicode byte to echo
942 * @tty: terminal device
943 *
944 * Echo user input back onto the screen. This must be called only when
945 * L_ECHO(tty) is true. Called from the driver receive_buf path.
946 *
947 * This variant tags control characters to be echoed as "^X"
948 * (where X is the letter representing the control char).
949 */
950
951static void echo_char(unsigned char c, struct tty_struct *tty)
952{
953 struct n_tty_data *ldata = tty->disc_data;
954
955 if (c == ECHO_OP_START) {
956 add_echo_byte(ECHO_OP_START, ldata);
957 add_echo_byte(ECHO_OP_START, ldata);
958 } else {
959 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
960 add_echo_byte(ECHO_OP_START, ldata);
961 add_echo_byte(c, ldata);
962 }
963}
964
965/**
966 * finish_erasing - complete erase
967 * @ldata: n_tty data
968 */
969
970static inline void finish_erasing(struct n_tty_data *ldata)
971{
972 if (ldata->erasing) {
973 echo_char_raw('/', ldata);
974 ldata->erasing = 0;
975 }
976}
977
978/**
979 * eraser - handle erase function
980 * @c: character input
981 * @tty: terminal device
982 *
983 * Perform erase and necessary output when an erase character is
984 * present in the stream from the driver layer. Handles the complexities
985 * of UTF-8 multibyte symbols.
986 *
987 * n_tty_receive_buf()/producer path:
988 * caller holds non-exclusive termios_rwsem
989 * modifies read_head
990 *
991 * Modifying the read_head is not considered a publish in this context
992 * because canonical mode is active -- only canon_head publishes
993 */
994
995static void eraser(unsigned char c, struct tty_struct *tty)
996{
997 struct n_tty_data *ldata = tty->disc_data;
998 enum { ERASE, WERASE, KILL } kill_type;
999 size_t head;
1000 size_t cnt;
1001 int seen_alnums;
1002
1003 if (ldata->read_head == ldata->canon_head) {
1004 /* process_output('\a', tty); */ /* what do you think? */
1005 return;
1006 }
1007 if (c == ERASE_CHAR(tty))
1008 kill_type = ERASE;
1009 else if (c == WERASE_CHAR(tty))
1010 kill_type = WERASE;
1011 else {
1012 if (!L_ECHO(tty)) {
1013 ldata->read_head = ldata->canon_head;
1014 return;
1015 }
1016 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1017 ldata->read_head = ldata->canon_head;
1018 finish_erasing(ldata);
1019 echo_char(KILL_CHAR(tty), tty);
1020 /* Add a newline if ECHOK is on and ECHOKE is off. */
1021 if (L_ECHOK(tty))
1022 echo_char_raw('\n', ldata);
1023 return;
1024 }
1025 kill_type = KILL;
1026 }
1027
1028 seen_alnums = 0;
1029 while (ldata->read_head != ldata->canon_head) {
1030 head = ldata->read_head;
1031
1032 /* erase a single possibly multibyte character */
1033 do {
1034 head--;
1035 c = read_buf(ldata, head);
1036 } while (is_continuation(c, tty) && head != ldata->canon_head);
1037
1038 /* do not partially erase */
1039 if (is_continuation(c, tty))
1040 break;
1041
1042 if (kill_type == WERASE) {
1043 /* Equivalent to BSD's ALTWERASE. */
1044 if (isalnum(c) || c == '_')
1045 seen_alnums++;
1046 else if (seen_alnums)
1047 break;
1048 }
1049 cnt = ldata->read_head - head;
1050 ldata->read_head = head;
1051 if (L_ECHO(tty)) {
1052 if (L_ECHOPRT(tty)) {
1053 if (!ldata->erasing) {
1054 echo_char_raw('\\', ldata);
1055 ldata->erasing = 1;
1056 }
1057 /* if cnt > 1, output a multi-byte character */
1058 echo_char(c, tty);
1059 while (--cnt > 0) {
1060 head++;
1061 echo_char_raw(read_buf(ldata, head), ldata);
1062 echo_move_back_col(ldata);
1063 }
1064 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1065 echo_char(ERASE_CHAR(tty), tty);
1066 } else if (c == '\t') {
1067 unsigned int num_chars = 0;
1068 int after_tab = 0;
1069 size_t tail = ldata->read_head;
1070
1071 /*
1072 * Count the columns used for characters
1073 * since the start of input or after a
1074 * previous tab.
1075 * This info is used to go back the correct
1076 * number of columns.
1077 */
1078 while (tail != ldata->canon_head) {
1079 tail--;
1080 c = read_buf(ldata, tail);
1081 if (c == '\t') {
1082 after_tab = 1;
1083 break;
1084 } else if (iscntrl(c)) {
1085 if (L_ECHOCTL(tty))
1086 num_chars += 2;
1087 } else if (!is_continuation(c, tty)) {
1088 num_chars++;
1089 }
1090 }
1091 echo_erase_tab(num_chars, after_tab, ldata);
1092 } else {
1093 if (iscntrl(c) && L_ECHOCTL(tty)) {
1094 echo_char_raw('\b', ldata);
1095 echo_char_raw(' ', ldata);
1096 echo_char_raw('\b', ldata);
1097 }
1098 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1099 echo_char_raw('\b', ldata);
1100 echo_char_raw(' ', ldata);
1101 echo_char_raw('\b', ldata);
1102 }
1103 }
1104 }
1105 if (kill_type == ERASE)
1106 break;
1107 }
1108 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1109 finish_erasing(ldata);
1110}
1111
1112/**
1113 * isig - handle the ISIG optio
1114 * @sig: signal
1115 * @tty: terminal
1116 *
1117 * Called when a signal is being sent due to terminal input.
1118 * Called from the driver receive_buf path so serialized.
1119 *
1120 * Locking: ctrl_lock
1121 */
1122
1123static void isig(int sig, struct tty_struct *tty)
1124{
1125 struct pid *tty_pgrp = tty_get_pgrp(tty);
1126 if (tty_pgrp) {
1127 kill_pgrp(tty_pgrp, sig, 1);
1128 put_pid(tty_pgrp);
1129 }
1130}
1131
1132/**
1133 * n_tty_receive_break - handle break
1134 * @tty: terminal
1135 *
1136 * An RS232 break event has been hit in the incoming bitstream. This
1137 * can cause a variety of events depending upon the termios settings.
1138 *
1139 * n_tty_receive_buf()/producer path:
1140 * caller holds non-exclusive termios_rwsem
1141 * publishes read_head via put_tty_queue()
1142 *
1143 * Note: may get exclusive termios_rwsem if flushing input buffer
1144 */
1145
1146static void n_tty_receive_break(struct tty_struct *tty)
1147{
1148 struct n_tty_data *ldata = tty->disc_data;
1149
1150 if (I_IGNBRK(tty))
1151 return;
1152 if (I_BRKINT(tty)) {
1153 isig(SIGINT, tty);
1154 if (!L_NOFLSH(tty)) {
1155 /* flushing needs exclusive termios_rwsem */
1156 up_read(&tty->termios_rwsem);
1157 n_tty_flush_buffer(tty);
1158 tty_driver_flush_buffer(tty);
1159 down_read(&tty->termios_rwsem);
1160 }
1161 return;
1162 }
1163 if (I_PARMRK(tty)) {
1164 put_tty_queue('\377', ldata);
1165 put_tty_queue('\0', ldata);
1166 }
1167 put_tty_queue('\0', ldata);
1168 if (waitqueue_active(&tty->read_wait))
1169 wake_up_interruptible(&tty->read_wait);
1170}
1171
1172/**
1173 * n_tty_receive_overrun - handle overrun reporting
1174 * @tty: terminal
1175 *
1176 * Data arrived faster than we could process it. While the tty
1177 * driver has flagged this the bits that were missed are gone
1178 * forever.
1179 *
1180 * Called from the receive_buf path so single threaded. Does not
1181 * need locking as num_overrun and overrun_time are function
1182 * private.
1183 */
1184
1185static void n_tty_receive_overrun(struct tty_struct *tty)
1186{
1187 struct n_tty_data *ldata = tty->disc_data;
1188 char buf[64];
1189
1190 ldata->num_overrun++;
1191 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1192 time_after(ldata->overrun_time, jiffies)) {
1193 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1194 tty_name(tty, buf),
1195 ldata->num_overrun);
1196 ldata->overrun_time = jiffies;
1197 ldata->num_overrun = 0;
1198 }
1199}
1200
1201/**
1202 * n_tty_receive_parity_error - error notifier
1203 * @tty: terminal device
1204 * @c: character
1205 *
1206 * Process a parity error and queue the right data to indicate
1207 * the error case if necessary.
1208 *
1209 * n_tty_receive_buf()/producer path:
1210 * caller holds non-exclusive termios_rwsem
1211 * publishes read_head via put_tty_queue()
1212 */
1213static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1214{
1215 struct n_tty_data *ldata = tty->disc_data;
1216
1217 if (I_IGNPAR(tty))
1218 return;
1219 if (I_PARMRK(tty)) {
1220 put_tty_queue('\377', ldata);
1221 put_tty_queue('\0', ldata);
1222 put_tty_queue(c, ldata);
1223 } else if (I_INPCK(tty))
1224 put_tty_queue('\0', ldata);
1225 else
1226 put_tty_queue(c, ldata);
1227 if (waitqueue_active(&tty->read_wait))
1228 wake_up_interruptible(&tty->read_wait);
1229}
1230
1231static void
1232n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1233{
1234 if (!L_NOFLSH(tty)) {
1235 /* flushing needs exclusive termios_rwsem */
1236 up_read(&tty->termios_rwsem);
1237 n_tty_flush_buffer(tty);
1238 tty_driver_flush_buffer(tty);
1239 down_read(&tty->termios_rwsem);
1240 }
1241 if (I_IXON(tty))
1242 start_tty(tty);
1243 if (L_ECHO(tty)) {
1244 echo_char(c, tty);
1245 commit_echoes(tty);
1246 } else
1247 process_echoes(tty);
1248 isig(signal, tty);
1249 return;
1250}
1251
1252/**
1253 * n_tty_receive_char - perform processing
1254 * @tty: terminal device
1255 * @c: character
1256 *
1257 * Process an individual character of input received from the driver.
1258 * This is serialized with respect to itself by the rules for the
1259 * driver above.
1260 *
1261 * n_tty_receive_buf()/producer path:
1262 * caller holds non-exclusive termios_rwsem
1263 * publishes canon_head if canonical mode is active
1264 * otherwise, publishes read_head via put_tty_queue()
1265 *
1266 * Returns 1 if LNEXT was received, else returns 0
1267 */
1268
1269static int
1270n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1271{
1272 struct n_tty_data *ldata = tty->disc_data;
1273
1274 if (I_IXON(tty)) {
1275 if (c == START_CHAR(tty)) {
1276 start_tty(tty);
1277 process_echoes(tty);
1278 return 0;
1279 }
1280 if (c == STOP_CHAR(tty)) {
1281 stop_tty(tty);
1282 return 0;
1283 }
1284 }
1285
1286 if (L_ISIG(tty)) {
1287 if (c == INTR_CHAR(tty)) {
1288 n_tty_receive_signal_char(tty, SIGINT, c);
1289 return 0;
1290 } else if (c == QUIT_CHAR(tty)) {
1291 n_tty_receive_signal_char(tty, SIGQUIT, c);
1292 return 0;
1293 } else if (c == SUSP_CHAR(tty)) {
1294 n_tty_receive_signal_char(tty, SIGTSTP, c);
1295 return 0;
1296 }
1297 }
1298
1299 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1300 start_tty(tty);
1301 process_echoes(tty);
1302 }
1303
1304 if (c == '\r') {
1305 if (I_IGNCR(tty))
1306 return 0;
1307 if (I_ICRNL(tty))
1308 c = '\n';
1309 } else if (c == '\n' && I_INLCR(tty))
1310 c = '\r';
1311
1312 if (ldata->icanon) {
1313 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1314 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1315 eraser(c, tty);
1316 commit_echoes(tty);
1317 return 0;
1318 }
1319 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1320 ldata->lnext = 1;
1321 if (L_ECHO(tty)) {
1322 finish_erasing(ldata);
1323 if (L_ECHOCTL(tty)) {
1324 echo_char_raw('^', ldata);
1325 echo_char_raw('\b', ldata);
1326 commit_echoes(tty);
1327 }
1328 }
1329 return 1;
1330 }
1331 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1332 size_t tail = ldata->canon_head;
1333
1334 finish_erasing(ldata);
1335 echo_char(c, tty);
1336 echo_char_raw('\n', ldata);
1337 while (tail != ldata->read_head) {
1338 echo_char(read_buf(ldata, tail), tty);
1339 tail++;
1340 }
1341 commit_echoes(tty);
1342 return 0;
1343 }
1344 if (c == '\n') {
1345 if (L_ECHO(tty) || L_ECHONL(tty)) {
1346 echo_char_raw('\n', ldata);
1347 commit_echoes(tty);
1348 }
1349 goto handle_newline;
1350 }
1351 if (c == EOF_CHAR(tty)) {
1352 c = __DISABLED_CHAR;
1353 goto handle_newline;
1354 }
1355 if ((c == EOL_CHAR(tty)) ||
1356 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1357 /*
1358 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1359 */
1360 if (L_ECHO(tty)) {
1361 /* Record the column of first canon char. */
1362 if (ldata->canon_head == ldata->read_head)
1363 echo_set_canon_col(ldata);
1364 echo_char(c, tty);
1365 commit_echoes(tty);
1366 }
1367 /*
1368 * XXX does PARMRK doubling happen for
1369 * EOL_CHAR and EOL2_CHAR?
1370 */
1371 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1372 put_tty_queue(c, ldata);
1373
1374handle_newline:
1375 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1376 put_tty_queue(c, ldata);
1377 ldata->canon_head = ldata->read_head;
1378 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1379 if (waitqueue_active(&tty->read_wait))
1380 wake_up_interruptible(&tty->read_wait);
1381 return 0;
1382 }
1383 }
1384
1385 if (L_ECHO(tty)) {
1386 finish_erasing(ldata);
1387 if (c == '\n')
1388 echo_char_raw('\n', ldata);
1389 else {
1390 /* Record the column of first canon char. */
1391 if (ldata->canon_head == ldata->read_head)
1392 echo_set_canon_col(ldata);
1393 echo_char(c, tty);
1394 }
1395 commit_echoes(tty);
1396 }
1397
1398 /* PARMRK doubling check */
1399 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1400 put_tty_queue(c, ldata);
1401
1402 put_tty_queue(c, ldata);
1403 return 0;
1404}
1405
1406static inline void
1407n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1408{
1409 struct n_tty_data *ldata = tty->disc_data;
1410
1411 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1412 start_tty(tty);
1413 process_echoes(tty);
1414 }
1415 if (L_ECHO(tty)) {
1416 finish_erasing(ldata);
1417 /* Record the column of first canon char. */
1418 if (ldata->canon_head == ldata->read_head)
1419 echo_set_canon_col(ldata);
1420 echo_char(c, tty);
1421 commit_echoes(tty);
1422 }
1423 /* PARMRK doubling check */
1424 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1425 put_tty_queue(c, ldata);
1426 put_tty_queue(c, ldata);
1427}
1428
1429static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1430{
1431 n_tty_receive_char_inline(tty, c);
1432}
1433
1434static inline void
1435n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1436{
1437 struct n_tty_data *ldata = tty->disc_data;
1438
1439 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1440 start_tty(tty);
1441 process_echoes(tty);
1442 }
1443 if (L_ECHO(tty)) {
1444 finish_erasing(ldata);
1445 /* Record the column of first canon char. */
1446 if (ldata->canon_head == ldata->read_head)
1447 echo_set_canon_col(ldata);
1448 echo_char(c, tty);
1449 commit_echoes(tty);
1450 }
1451 put_tty_queue(c, ldata);
1452}
1453
1454static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1455{
1456 if (I_ISTRIP(tty))
1457 c &= 0x7f;
1458 if (I_IUCLC(tty) && L_IEXTEN(tty))
1459 c = tolower(c);
1460
1461 if (I_IXON(tty)) {
1462 if (c == STOP_CHAR(tty))
1463 stop_tty(tty);
1464 else if (c == START_CHAR(tty) ||
1465 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1466 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1467 c != SUSP_CHAR(tty))) {
1468 start_tty(tty);
1469 process_echoes(tty);
1470 }
1471 }
1472}
1473
1474static void
1475n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1476{
1477 char buf[64];
1478
1479 switch (flag) {
1480 case TTY_BREAK:
1481 n_tty_receive_break(tty);
1482 break;
1483 case TTY_PARITY:
1484 case TTY_FRAME:
1485 n_tty_receive_parity_error(tty, c);
1486 break;
1487 case TTY_OVERRUN:
1488 n_tty_receive_overrun(tty);
1489 break;
1490 default:
1491 printk(KERN_ERR "%s: unknown flag %d\n",
1492 tty_name(tty, buf), flag);
1493 break;
1494 }
1495}
1496
1497static void
1498n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1499{
1500 struct n_tty_data *ldata = tty->disc_data;
1501
1502 ldata->lnext = 0;
1503 if (likely(flag == TTY_NORMAL)) {
1504 if (I_ISTRIP(tty))
1505 c &= 0x7f;
1506 if (I_IUCLC(tty) && L_IEXTEN(tty))
1507 c = tolower(c);
1508 n_tty_receive_char(tty, c);
1509 } else
1510 n_tty_receive_char_flagged(tty, c, flag);
1511}
1512
1513/**
1514 * n_tty_receive_buf - data receive
1515 * @tty: terminal device
1516 * @cp: buffer
1517 * @fp: flag buffer
1518 * @count: characters
1519 *
1520 * Called by the terminal driver when a block of characters has
1521 * been received. This function must be called from soft contexts
1522 * not from interrupt context. The driver is responsible for making
1523 * calls one at a time and in order (or using flush_to_ldisc)
1524 *
1525 * n_tty_receive_buf()/producer path:
1526 * claims non-exclusive termios_rwsem
1527 * publishes read_head and canon_head
1528 */
1529
1530static void
1531n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1532 char *fp, int count)
1533{
1534 struct n_tty_data *ldata = tty->disc_data;
1535 size_t n, head;
1536
1537 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1538 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1539 n = min_t(size_t, count, n);
1540 memcpy(read_buf_addr(ldata, head), cp, n);
1541 ldata->read_head += n;
1542 cp += n;
1543 count -= n;
1544
1545 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1546 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1547 n = min_t(size_t, count, n);
1548 memcpy(read_buf_addr(ldata, head), cp, n);
1549 ldata->read_head += n;
1550}
1551
1552static void
1553n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1554 char *fp, int count)
1555{
1556 struct n_tty_data *ldata = tty->disc_data;
1557 char flag = TTY_NORMAL;
1558
1559 while (count--) {
1560 if (fp)
1561 flag = *fp++;
1562 if (likely(flag == TTY_NORMAL))
1563 put_tty_queue(*cp++, ldata);
1564 else
1565 n_tty_receive_char_flagged(tty, *cp++, flag);
1566 }
1567}
1568
1569static void
1570n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1571 char *fp, int count)
1572{
1573 char flag = TTY_NORMAL;
1574
1575 while (count--) {
1576 if (fp)
1577 flag = *fp++;
1578 if (likely(flag == TTY_NORMAL))
1579 n_tty_receive_char_closing(tty, *cp++);
1580 else
1581 n_tty_receive_char_flagged(tty, *cp++, flag);
1582 }
1583}
1584
1585static void
1586n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1587 char *fp, int count)
1588{
1589 struct n_tty_data *ldata = tty->disc_data;
1590 char flag = TTY_NORMAL;
1591
1592 while (count--) {
1593 if (fp)
1594 flag = *fp++;
1595 if (likely(flag == TTY_NORMAL)) {
1596 unsigned char c = *cp++;
1597
1598 if (I_ISTRIP(tty))
1599 c &= 0x7f;
1600 if (I_IUCLC(tty) && L_IEXTEN(tty))
1601 c = tolower(c);
1602 if (L_EXTPROC(tty)) {
1603 put_tty_queue(c, ldata);
1604 continue;
1605 }
1606 if (!test_bit(c, ldata->char_map))
1607 n_tty_receive_char_inline(tty, c);
1608 else if (n_tty_receive_char_special(tty, c) && count) {
1609 if (fp)
1610 flag = *fp++;
1611 n_tty_receive_char_lnext(tty, *cp++, flag);
1612 count--;
1613 }
1614 } else
1615 n_tty_receive_char_flagged(tty, *cp++, flag);
1616 }
1617}
1618
1619static void
1620n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1621 char *fp, int count)
1622{
1623 struct n_tty_data *ldata = tty->disc_data;
1624 char flag = TTY_NORMAL;
1625
1626 while (count--) {
1627 if (fp)
1628 flag = *fp++;
1629 if (likely(flag == TTY_NORMAL)) {
1630 unsigned char c = *cp++;
1631
1632 if (!test_bit(c, ldata->char_map))
1633 n_tty_receive_char_fast(tty, c);
1634 else if (n_tty_receive_char_special(tty, c) && count) {
1635 if (fp)
1636 flag = *fp++;
1637 n_tty_receive_char_lnext(tty, *cp++, flag);
1638 count--;
1639 }
1640 } else
1641 n_tty_receive_char_flagged(tty, *cp++, flag);
1642 }
1643}
1644
1645static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1646 char *fp, int count)
1647{
1648 struct n_tty_data *ldata = tty->disc_data;
1649 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1650
1651 if (ldata->real_raw)
1652 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1653 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1654 n_tty_receive_buf_raw(tty, cp, fp, count);
1655 else if (tty->closing && !L_EXTPROC(tty))
1656 n_tty_receive_buf_closing(tty, cp, fp, count);
1657 else {
1658 if (ldata->lnext) {
1659 char flag = TTY_NORMAL;
1660
1661 if (fp)
1662 flag = *fp++;
1663 n_tty_receive_char_lnext(tty, *cp++, flag);
1664 count--;
1665 }
1666
1667 if (!preops && !I_PARMRK(tty))
1668 n_tty_receive_buf_fast(tty, cp, fp, count);
1669 else
1670 n_tty_receive_buf_standard(tty, cp, fp, count);
1671
1672 flush_echoes(tty);
1673 if (tty->ops->flush_chars)
1674 tty->ops->flush_chars(tty);
1675 }
1676
1677 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1678 L_EXTPROC(tty)) {
1679 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1680 if (waitqueue_active(&tty->read_wait))
1681 wake_up_interruptible(&tty->read_wait);
1682 }
1683}
1684
1685static int
1686n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1687 char *fp, int count, int flow)
1688{
1689 struct n_tty_data *ldata = tty->disc_data;
1690 int room, n, rcvd = 0;
1691
1692 down_read(&tty->termios_rwsem);
1693
1694 while (1) {
1695 room = receive_room(tty);
1696 n = min(count, room);
1697 if (!n) {
1698 if (flow && !room)
1699 ldata->no_room = 1;
1700 break;
1701 }
1702 __receive_buf(tty, cp, fp, n);
1703 cp += n;
1704 if (fp)
1705 fp += n;
1706 count -= n;
1707 rcvd += n;
1708 }
1709
1710 tty->receive_room = room;
1711 n_tty_check_throttle(tty);
1712 up_read(&tty->termios_rwsem);
1713
1714 return rcvd;
1715}
1716
1717static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1718 char *fp, int count)
1719{
1720 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1721}
1722
1723static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1724 char *fp, int count)
1725{
1726 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1727}
1728
1729int is_ignored(int sig)
1730{
1731 return (sigismember(¤t->blocked, sig) ||
1732 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1733}
1734
1735/**
1736 * n_tty_set_termios - termios data changed
1737 * @tty: terminal
1738 * @old: previous data
1739 *
1740 * Called by the tty layer when the user changes termios flags so
1741 * that the line discipline can plan ahead. This function cannot sleep
1742 * and is protected from re-entry by the tty layer. The user is
1743 * guaranteed that this function will not be re-entered or in progress
1744 * when the ldisc is closed.
1745 *
1746 * Locking: Caller holds tty->termios_rwsem
1747 */
1748
1749static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1750{
1751 struct n_tty_data *ldata = tty->disc_data;
1752
1753 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1754 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1755 ldata->line_start = ldata->read_tail;
1756 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1757 ldata->canon_head = ldata->read_tail;
1758 ldata->push = 0;
1759 } else {
1760 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1761 ldata->read_flags);
1762 ldata->canon_head = ldata->read_head;
1763 ldata->push = 1;
1764 }
1765 ldata->erasing = 0;
1766 ldata->lnext = 0;
1767 }
1768
1769 ldata->icanon = (L_ICANON(tty) != 0);
1770
1771 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1772 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1773 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1774 I_PARMRK(tty)) {
1775 bitmap_zero(ldata->char_map, 256);
1776
1777 if (I_IGNCR(tty) || I_ICRNL(tty))
1778 set_bit('\r', ldata->char_map);
1779 if (I_INLCR(tty))
1780 set_bit('\n', ldata->char_map);
1781
1782 if (L_ICANON(tty)) {
1783 set_bit(ERASE_CHAR(tty), ldata->char_map);
1784 set_bit(KILL_CHAR(tty), ldata->char_map);
1785 set_bit(EOF_CHAR(tty), ldata->char_map);
1786 set_bit('\n', ldata->char_map);
1787 set_bit(EOL_CHAR(tty), ldata->char_map);
1788 if (L_IEXTEN(tty)) {
1789 set_bit(WERASE_CHAR(tty), ldata->char_map);
1790 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1791 set_bit(EOL2_CHAR(tty), ldata->char_map);
1792 if (L_ECHO(tty))
1793 set_bit(REPRINT_CHAR(tty),
1794 ldata->char_map);
1795 }
1796 }
1797 if (I_IXON(tty)) {
1798 set_bit(START_CHAR(tty), ldata->char_map);
1799 set_bit(STOP_CHAR(tty), ldata->char_map);
1800 }
1801 if (L_ISIG(tty)) {
1802 set_bit(INTR_CHAR(tty), ldata->char_map);
1803 set_bit(QUIT_CHAR(tty), ldata->char_map);
1804 set_bit(SUSP_CHAR(tty), ldata->char_map);
1805 }
1806 clear_bit(__DISABLED_CHAR, ldata->char_map);
1807 ldata->raw = 0;
1808 ldata->real_raw = 0;
1809 } else {
1810 ldata->raw = 1;
1811 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1812 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1813 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1814 ldata->real_raw = 1;
1815 else
1816 ldata->real_raw = 0;
1817 }
1818 n_tty_set_room(tty);
1819 /*
1820 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1821 * been stopped by STOP_CHAR(tty) before it.
1822 */
1823 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1824 start_tty(tty);
1825 process_echoes(tty);
1826 }
1827
1828 /* The termios change make the tty ready for I/O */
1829 if (waitqueue_active(&tty->write_wait))
1830 wake_up_interruptible(&tty->write_wait);
1831 if (waitqueue_active(&tty->read_wait))
1832 wake_up_interruptible(&tty->read_wait);
1833}
1834
1835/**
1836 * n_tty_close - close the ldisc for this tty
1837 * @tty: device
1838 *
1839 * Called from the terminal layer when this line discipline is
1840 * being shut down, either because of a close or becsuse of a
1841 * discipline change. The function will not be called while other
1842 * ldisc methods are in progress.
1843 */
1844
1845static void n_tty_close(struct tty_struct *tty)
1846{
1847 struct n_tty_data *ldata = tty->disc_data;
1848
1849 if (tty->link)
1850 n_tty_packet_mode_flush(tty);
1851
1852 vfree(ldata);
1853 tty->disc_data = NULL;
1854}
1855
1856/**
1857 * n_tty_open - open an ldisc
1858 * @tty: terminal to open
1859 *
1860 * Called when this line discipline is being attached to the
1861 * terminal device. Can sleep. Called serialized so that no
1862 * other events will occur in parallel. No further open will occur
1863 * until a close.
1864 */
1865
1866static int n_tty_open(struct tty_struct *tty)
1867{
1868 struct n_tty_data *ldata;
1869
1870 /* Currently a malloc failure here can panic */
1871 ldata = vmalloc(sizeof(*ldata));
1872 if (!ldata)
1873 goto err;
1874
1875 ldata->overrun_time = jiffies;
1876 mutex_init(&ldata->atomic_read_lock);
1877 mutex_init(&ldata->output_lock);
1878
1879 tty->disc_data = ldata;
1880 reset_buffer_flags(tty->disc_data);
1881 ldata->column = 0;
1882 ldata->canon_column = 0;
1883 ldata->minimum_to_wake = 1;
1884 ldata->num_overrun = 0;
1885 ldata->no_room = 0;
1886 ldata->lnext = 0;
1887 tty->closing = 0;
1888 /* indicate buffer work may resume */
1889 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1890 n_tty_set_termios(tty, NULL);
1891 tty_unthrottle(tty);
1892
1893 return 0;
1894err:
1895 return -ENOMEM;
1896}
1897
1898static inline int input_available_p(struct tty_struct *tty, int poll)
1899{
1900 struct n_tty_data *ldata = tty->disc_data;
1901 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
1902
1903 if (ldata->icanon && !L_EXTPROC(tty))
1904 return ldata->canon_head != ldata->read_tail;
1905 else
1906 return read_cnt(ldata) >= amt;
1907}
1908
1909/**
1910 * copy_from_read_buf - copy read data directly
1911 * @tty: terminal device
1912 * @b: user data
1913 * @nr: size of data
1914 *
1915 * Helper function to speed up n_tty_read. It is only called when
1916 * ICANON is off; it copies characters straight from the tty queue to
1917 * user space directly. It can be profitably called twice; once to
1918 * drain the space from the tail pointer to the (physical) end of the
1919 * buffer, and once to drain the space from the (physical) beginning of
1920 * the buffer to head pointer.
1921 *
1922 * Called under the ldata->atomic_read_lock sem
1923 *
1924 * n_tty_read()/consumer path:
1925 * caller holds non-exclusive termios_rwsem
1926 * read_tail published
1927 */
1928
1929static int copy_from_read_buf(struct tty_struct *tty,
1930 unsigned char __user **b,
1931 size_t *nr)
1932
1933{
1934 struct n_tty_data *ldata = tty->disc_data;
1935 int retval;
1936 size_t n;
1937 bool is_eof;
1938 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1939
1940 retval = 0;
1941 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1942 n = min(*nr, n);
1943 if (n) {
1944 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1945 n -= retval;
1946 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1947 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1948 ldata->icanon);
1949 ldata->read_tail += n;
1950 /* Turn single EOF into zero-length read */
1951 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1952 n = 0;
1953 *b += n;
1954 *nr -= n;
1955 }
1956 return retval;
1957}
1958
1959/**
1960 * canon_copy_from_read_buf - copy read data in canonical mode
1961 * @tty: terminal device
1962 * @b: user data
1963 * @nr: size of data
1964 *
1965 * Helper function for n_tty_read. It is only called when ICANON is on;
1966 * it copies one line of input up to and including the line-delimiting
1967 * character into the user-space buffer.
1968 *
1969 * NB: When termios is changed from non-canonical to canonical mode and
1970 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1971 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1972 * This causes data already processed as input to be immediately available
1973 * as input although a newline has not been received.
1974 *
1975 * Called under the atomic_read_lock mutex
1976 *
1977 * n_tty_read()/consumer path:
1978 * caller holds non-exclusive termios_rwsem
1979 * read_tail published
1980 */
1981
1982static int canon_copy_from_read_buf(struct tty_struct *tty,
1983 unsigned char __user **b,
1984 size_t *nr)
1985{
1986 struct n_tty_data *ldata = tty->disc_data;
1987 size_t n, size, more, c;
1988 size_t eol;
1989 size_t tail;
1990 int ret, found = 0;
1991 bool eof_push = 0;
1992
1993 /* N.B. avoid overrun if nr == 0 */
1994 n = min(*nr, read_cnt(ldata));
1995 if (!n)
1996 return 0;
1997
1998 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1999 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
2000
2001 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2002 __func__, *nr, tail, n, size);
2003
2004 eol = find_next_bit(ldata->read_flags, size, tail);
2005 more = n - (size - tail);
2006 if (eol == N_TTY_BUF_SIZE && more) {
2007 /* scan wrapped without finding set bit */
2008 eol = find_next_bit(ldata->read_flags, more, 0);
2009 if (eol != more)
2010 found = 1;
2011 } else if (eol != size)
2012 found = 1;
2013
2014 size = N_TTY_BUF_SIZE - tail;
2015 n = eol - tail;
2016 if (n > 4096)
2017 n += 4096;
2018 n += found;
2019 c = n;
2020
2021 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
2022 n--;
2023 eof_push = !n && ldata->read_tail != ldata->line_start;
2024 }
2025
2026 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2027 __func__, eol, found, n, c, size, more);
2028
2029 if (n > size) {
2030 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2031 if (ret)
2032 return -EFAULT;
2033 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2034 } else
2035 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2036
2037 if (ret)
2038 return -EFAULT;
2039 *b += n;
2040 *nr -= n;
2041
2042 if (found)
2043 clear_bit(eol, ldata->read_flags);
2044 smp_mb__after_clear_bit();
2045 ldata->read_tail += c;
2046
2047 if (found) {
2048 if (!ldata->push)
2049 ldata->line_start = ldata->read_tail;
2050 else
2051 ldata->push = 0;
2052 tty_audit_push(tty);
2053 }
2054 return eof_push ? -EAGAIN : 0;
2055}
2056
2057extern ssize_t redirected_tty_write(struct file *, const char __user *,
2058 size_t, loff_t *);
2059
2060/**
2061 * job_control - check job control
2062 * @tty: tty
2063 * @file: file handle
2064 *
2065 * Perform job control management checks on this file/tty descriptor
2066 * and if appropriate send any needed signals and return a negative
2067 * error code if action should be taken.
2068 *
2069 * Locking: redirected write test is safe
2070 * current->signal->tty check is safe
2071 * ctrl_lock to safely reference tty->pgrp
2072 */
2073
2074static int job_control(struct tty_struct *tty, struct file *file)
2075{
2076 /* Job control check -- must be done at start and after
2077 every sleep (POSIX.1 7.1.1.4). */
2078 /* NOTE: not yet done after every sleep pending a thorough
2079 check of the logic of this change. -- jlc */
2080 /* don't stop on /dev/console */
2081 if (file->f_op->write == redirected_tty_write ||
2082 current->signal->tty != tty)
2083 return 0;
2084
2085 spin_lock_irq(&tty->ctrl_lock);
2086 if (!tty->pgrp)
2087 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2088 else if (task_pgrp(current) != tty->pgrp) {
2089 spin_unlock_irq(&tty->ctrl_lock);
2090 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2091 return -EIO;
2092 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2093 set_thread_flag(TIF_SIGPENDING);
2094 return -ERESTARTSYS;
2095 }
2096 spin_unlock_irq(&tty->ctrl_lock);
2097 return 0;
2098}
2099
2100
2101/**
2102 * n_tty_read - read function for tty
2103 * @tty: tty device
2104 * @file: file object
2105 * @buf: userspace buffer pointer
2106 * @nr: size of I/O
2107 *
2108 * Perform reads for the line discipline. We are guaranteed that the
2109 * line discipline will not be closed under us but we may get multiple
2110 * parallel readers and must handle this ourselves. We may also get
2111 * a hangup. Always called in user context, may sleep.
2112 *
2113 * This code must be sure never to sleep through a hangup.
2114 *
2115 * n_tty_read()/consumer path:
2116 * claims non-exclusive termios_rwsem
2117 * publishes read_tail
2118 */
2119
2120static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2121 unsigned char __user *buf, size_t nr)
2122{
2123 struct n_tty_data *ldata = tty->disc_data;
2124 unsigned char __user *b = buf;
2125 DECLARE_WAITQUEUE(wait, current);
2126 int c;
2127 int minimum, time;
2128 ssize_t retval = 0;
2129 long timeout;
2130 unsigned long flags;
2131 int packet;
2132
2133 c = job_control(tty, file);
2134 if (c < 0)
2135 return c;
2136
2137 /*
2138 * Internal serialization of reads.
2139 */
2140 if (file->f_flags & O_NONBLOCK) {
2141 if (!mutex_trylock(&ldata->atomic_read_lock))
2142 return -EAGAIN;
2143 } else {
2144 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2145 return -ERESTARTSYS;
2146 }
2147
2148 down_read(&tty->termios_rwsem);
2149
2150 minimum = time = 0;
2151 timeout = MAX_SCHEDULE_TIMEOUT;
2152 if (!ldata->icanon) {
2153 minimum = MIN_CHAR(tty);
2154 if (minimum) {
2155 time = (HZ / 10) * TIME_CHAR(tty);
2156 if (time)
2157 ldata->minimum_to_wake = 1;
2158 else if (!waitqueue_active(&tty->read_wait) ||
2159 (ldata->minimum_to_wake > minimum))
2160 ldata->minimum_to_wake = minimum;
2161 } else {
2162 timeout = (HZ / 10) * TIME_CHAR(tty);
2163 ldata->minimum_to_wake = minimum = 1;
2164 }
2165 }
2166
2167 packet = tty->packet;
2168
2169 add_wait_queue(&tty->read_wait, &wait);
2170 while (nr) {
2171 /* First test for status change. */
2172 if (packet && tty->link->ctrl_status) {
2173 unsigned char cs;
2174 if (b != buf)
2175 break;
2176 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
2177 cs = tty->link->ctrl_status;
2178 tty->link->ctrl_status = 0;
2179 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2180 if (tty_put_user(tty, cs, b++)) {
2181 retval = -EFAULT;
2182 b--;
2183 break;
2184 }
2185 nr--;
2186 break;
2187 }
2188 /* This statement must be first before checking for input
2189 so that any interrupt will set the state back to
2190 TASK_RUNNING. */
2191 set_current_state(TASK_INTERRUPTIBLE);
2192
2193 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2194 ((minimum - (b - buf)) >= 1))
2195 ldata->minimum_to_wake = (minimum - (b - buf));
2196
2197 if (!input_available_p(tty, 0)) {
2198 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2199 up_read(&tty->termios_rwsem);
2200 tty_flush_to_ldisc(tty);
2201 down_read(&tty->termios_rwsem);
2202 if (!input_available_p(tty, 0)) {
2203 retval = -EIO;
2204 break;
2205 }
2206 } else {
2207 if (tty_hung_up_p(file))
2208 break;
2209 if (!timeout)
2210 break;
2211 if (file->f_flags & O_NONBLOCK) {
2212 retval = -EAGAIN;
2213 break;
2214 }
2215 if (signal_pending(current)) {
2216 retval = -ERESTARTSYS;
2217 break;
2218 }
2219 n_tty_set_room(tty);
2220 up_read(&tty->termios_rwsem);
2221
2222 timeout = schedule_timeout(timeout);
2223
2224 down_read(&tty->termios_rwsem);
2225 continue;
2226 }
2227 }
2228 __set_current_state(TASK_RUNNING);
2229
2230 /* Deal with packet mode. */
2231 if (packet && b == buf) {
2232 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2233 retval = -EFAULT;
2234 b--;
2235 break;
2236 }
2237 nr--;
2238 }
2239
2240 if (ldata->icanon && !L_EXTPROC(tty)) {
2241 retval = canon_copy_from_read_buf(tty, &b, &nr);
2242 if (retval == -EAGAIN) {
2243 retval = 0;
2244 continue;
2245 } else if (retval)
2246 break;
2247 } else {
2248 int uncopied;
2249 /* The copy function takes the read lock and handles
2250 locking internally for this case */
2251 uncopied = copy_from_read_buf(tty, &b, &nr);
2252 uncopied += copy_from_read_buf(tty, &b, &nr);
2253 if (uncopied) {
2254 retval = -EFAULT;
2255 break;
2256 }
2257 }
2258
2259 n_tty_check_unthrottle(tty);
2260
2261 if (b - buf >= minimum)
2262 break;
2263 if (time)
2264 timeout = time;
2265 }
2266 n_tty_set_room(tty);
2267 up_read(&tty->termios_rwsem);
2268
2269 remove_wait_queue(&tty->read_wait, &wait);
2270 if (!waitqueue_active(&tty->read_wait))
2271 ldata->minimum_to_wake = minimum;
2272
2273 mutex_unlock(&ldata->atomic_read_lock);
2274
2275 __set_current_state(TASK_RUNNING);
2276 if (b - buf)
2277 retval = b - buf;
2278
2279 return retval;
2280}
2281
2282/**
2283 * n_tty_write - write function for tty
2284 * @tty: tty device
2285 * @file: file object
2286 * @buf: userspace buffer pointer
2287 * @nr: size of I/O
2288 *
2289 * Write function of the terminal device. This is serialized with
2290 * respect to other write callers but not to termios changes, reads
2291 * and other such events. Since the receive code will echo characters,
2292 * thus calling driver write methods, the output_lock is used in
2293 * the output processing functions called here as well as in the
2294 * echo processing function to protect the column state and space
2295 * left in the buffer.
2296 *
2297 * This code must be sure never to sleep through a hangup.
2298 *
2299 * Locking: output_lock to protect column state and space left
2300 * (note that the process_output*() functions take this
2301 * lock themselves)
2302 */
2303
2304static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2305 const unsigned char *buf, size_t nr)
2306{
2307 const unsigned char *b = buf;
2308 DECLARE_WAITQUEUE(wait, current);
2309 int c;
2310 ssize_t retval = 0;
2311
2312 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2313 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2314 retval = tty_check_change(tty);
2315 if (retval)
2316 return retval;
2317 }
2318
2319 down_read(&tty->termios_rwsem);
2320
2321 /* Write out any echoed characters that are still pending */
2322 process_echoes(tty);
2323
2324 add_wait_queue(&tty->write_wait, &wait);
2325 while (1) {
2326 set_current_state(TASK_INTERRUPTIBLE);
2327 if (signal_pending(current)) {
2328 retval = -ERESTARTSYS;
2329 break;
2330 }
2331 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2332 retval = -EIO;
2333 break;
2334 }
2335 if (O_OPOST(tty)) {
2336 while (nr > 0) {
2337 ssize_t num = process_output_block(tty, b, nr);
2338 if (num < 0) {
2339 if (num == -EAGAIN)
2340 break;
2341 retval = num;
2342 goto break_out;
2343 }
2344 b += num;
2345 nr -= num;
2346 if (nr == 0)
2347 break;
2348 c = *b;
2349 if (process_output(c, tty) < 0)
2350 break;
2351 b++; nr--;
2352 }
2353 if (tty->ops->flush_chars)
2354 tty->ops->flush_chars(tty);
2355 } else {
2356 struct n_tty_data *ldata = tty->disc_data;
2357
2358 while (nr > 0) {
2359 mutex_lock(&ldata->output_lock);
2360 c = tty->ops->write(tty, b, nr);
2361 mutex_unlock(&ldata->output_lock);
2362 if (c < 0) {
2363 retval = c;
2364 goto break_out;
2365 }
2366 if (!c)
2367 break;
2368 b += c;
2369 nr -= c;
2370 }
2371 }
2372 if (!nr)
2373 break;
2374 if (file->f_flags & O_NONBLOCK) {
2375 retval = -EAGAIN;
2376 break;
2377 }
2378 up_read(&tty->termios_rwsem);
2379
2380 schedule();
2381
2382 down_read(&tty->termios_rwsem);
2383 }
2384break_out:
2385 __set_current_state(TASK_RUNNING);
2386 remove_wait_queue(&tty->write_wait, &wait);
2387 if (b - buf != nr && tty->fasync)
2388 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2389 up_read(&tty->termios_rwsem);
2390 return (b - buf) ? b - buf : retval;
2391}
2392
2393/**
2394 * n_tty_poll - poll method for N_TTY
2395 * @tty: terminal device
2396 * @file: file accessing it
2397 * @wait: poll table
2398 *
2399 * Called when the line discipline is asked to poll() for data or
2400 * for special events. This code is not serialized with respect to
2401 * other events save open/close.
2402 *
2403 * This code must be sure never to sleep through a hangup.
2404 * Called without the kernel lock held - fine
2405 */
2406
2407static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2408 poll_table *wait)
2409{
2410 struct n_tty_data *ldata = tty->disc_data;
2411 unsigned int mask = 0;
2412
2413 poll_wait(file, &tty->read_wait, wait);
2414 poll_wait(file, &tty->write_wait, wait);
2415 if (input_available_p(tty, 1))
2416 mask |= POLLIN | POLLRDNORM;
2417 if (tty->packet && tty->link->ctrl_status)
2418 mask |= POLLPRI | POLLIN | POLLRDNORM;
2419 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2420 mask |= POLLHUP;
2421 if (tty_hung_up_p(file))
2422 mask |= POLLHUP;
2423 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2424 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2425 ldata->minimum_to_wake = MIN_CHAR(tty);
2426 else
2427 ldata->minimum_to_wake = 1;
2428 }
2429 if (tty->ops->write && !tty_is_writelocked(tty) &&
2430 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2431 tty_write_room(tty) > 0)
2432 mask |= POLLOUT | POLLWRNORM;
2433 return mask;
2434}
2435
2436static unsigned long inq_canon(struct n_tty_data *ldata)
2437{
2438 size_t nr, head, tail;
2439
2440 if (ldata->canon_head == ldata->read_tail)
2441 return 0;
2442 head = ldata->canon_head;
2443 tail = ldata->read_tail;
2444 nr = head - tail;
2445 /* Skip EOF-chars.. */
2446 while (head != tail) {
2447 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2448 read_buf(ldata, tail) == __DISABLED_CHAR)
2449 nr--;
2450 tail++;
2451 }
2452 return nr;
2453}
2454
2455static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2456 unsigned int cmd, unsigned long arg)
2457{
2458 struct n_tty_data *ldata = tty->disc_data;
2459 int retval;
2460
2461 switch (cmd) {
2462 case TIOCOUTQ:
2463 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2464 case TIOCINQ:
2465 down_write(&tty->termios_rwsem);
2466 if (L_ICANON(tty))
2467 retval = inq_canon(ldata);
2468 else
2469 retval = read_cnt(ldata);
2470 up_write(&tty->termios_rwsem);
2471 return put_user(retval, (unsigned int __user *) arg);
2472 default:
2473 return n_tty_ioctl_helper(tty, file, cmd, arg);
2474 }
2475}
2476
2477static void n_tty_fasync(struct tty_struct *tty, int on)
2478{
2479 struct n_tty_data *ldata = tty->disc_data;
2480
2481 if (!waitqueue_active(&tty->read_wait)) {
2482 if (on)
2483 ldata->minimum_to_wake = 1;
2484 else if (!tty->fasync)
2485 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2486 }
2487}
2488
2489struct tty_ldisc_ops tty_ldisc_N_TTY = {
2490 .magic = TTY_LDISC_MAGIC,
2491 .name = "n_tty",
2492 .open = n_tty_open,
2493 .close = n_tty_close,
2494 .flush_buffer = n_tty_flush_buffer,
2495 .chars_in_buffer = n_tty_chars_in_buffer,
2496 .read = n_tty_read,
2497 .write = n_tty_write,
2498 .ioctl = n_tty_ioctl,
2499 .set_termios = n_tty_set_termios,
2500 .poll = n_tty_poll,
2501 .receive_buf = n_tty_receive_buf,
2502 .write_wakeup = n_tty_write_wakeup,
2503 .fasync = n_tty_fasync,
2504 .receive_buf2 = n_tty_receive_buf2,
2505};
2506
2507/**
2508 * n_tty_inherit_ops - inherit N_TTY methods
2509 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2510 *
2511 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2512 * methods.
2513 */
2514
2515void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2516{
2517 *ops = tty_ldisc_N_TTY;
2518 ops->owner = NULL;
2519 ops->refcount = ops->flags = 0;
2520}
2521EXPORT_SYMBOL_GPL(n_tty_inherit_ops);