aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/tty/n_tty.c
diff options
context:
space:
mode:
authorGreg Kroah-Hartman <gregkh@suse.de>2010-11-04 14:10:29 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2010-11-05 11:10:33 -0400
commit96fd7ce58ffb5c7bf376796b5525ba3ea1c9d69f (patch)
treeaca24a6c1c0e506d5fa7b0266c4c1866786607ae /drivers/tty/n_tty.c
parentc8ddb2713c624f432fa5fe3c7ecffcdda46ea0d4 (diff)
TTY: create drivers/tty and move the tty core files there
The tty code should be in its own subdirectory and not in the char driver with all of the cruft that is currently there. Based on work done by Arnd Bergmann <arnd@arndb.de> Acked-by: Arnd Bergmann <arnd@arndb.de> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c2121
1 files changed, 2121 insertions, 0 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
new file mode 100644
index 000000000000..428f4fe0b5f7
--- /dev/null
+++ b/drivers/tty/n_tty.c
@@ -0,0 +1,2121 @@
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
99 /*
100 * If we are doing input canonicalization, and there are no
101 * pending newlines, let characters through without limit, so
102 * that erase characters will be handled. Other excess
103 * characters will be beeped.
104 */
105 if (left <= 0)
106 left = tty->icanon && !tty->canon_data;
107 tty->receive_room = left;
108}
109
110static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
111{
112 if (tty->read_cnt < N_TTY_BUF_SIZE) {
113 tty->read_buf[tty->read_head] = c;
114 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
115 tty->read_cnt++;
116 }
117}
118
119/**
120 * put_tty_queue - add character to tty
121 * @c: character
122 * @tty: tty device
123 *
124 * Add a character to the tty read_buf queue. This is done under the
125 * read_lock to serialize character addition and also to protect us
126 * against parallel reads or flushes
127 */
128
129static void put_tty_queue(unsigned char c, struct tty_struct *tty)
130{
131 unsigned long flags;
132 /*
133 * The problem of stomping on the buffers ends here.
134 * Why didn't anyone see this one coming? --AJK
135 */
136 spin_lock_irqsave(&tty->read_lock, flags);
137 put_tty_queue_nolock(c, tty);
138 spin_unlock_irqrestore(&tty->read_lock, flags);
139}
140
141/**
142 * check_unthrottle - allow new receive data
143 * @tty; tty device
144 *
145 * Check whether to call the driver unthrottle functions
146 *
147 * Can sleep, may be called under the atomic_read_lock mutex but
148 * this is not guaranteed.
149 */
150static void check_unthrottle(struct tty_struct *tty)
151{
152 if (tty->count)
153 tty_unthrottle(tty);
154}
155
156/**
157 * reset_buffer_flags - reset buffer state
158 * @tty: terminal to reset
159 *
160 * Reset the read buffer counters, clear the flags,
161 * and make sure the driver is unthrottled. Called
162 * from n_tty_open() and n_tty_flush_buffer().
163 *
164 * Locking: tty_read_lock for read fields.
165 */
166
167static void reset_buffer_flags(struct tty_struct *tty)
168{
169 unsigned long flags;
170
171 spin_lock_irqsave(&tty->read_lock, flags);
172 tty->read_head = tty->read_tail = tty->read_cnt = 0;
173 spin_unlock_irqrestore(&tty->read_lock, flags);
174
175 mutex_lock(&tty->echo_lock);
176 tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
177 mutex_unlock(&tty->echo_lock);
178
179 tty->canon_head = tty->canon_data = tty->erasing = 0;
180 memset(&tty->read_flags, 0, sizeof tty->read_flags);
181 n_tty_set_room(tty);
182 check_unthrottle(tty);
183}
184
185/**
186 * n_tty_flush_buffer - clean input queue
187 * @tty: terminal device
188 *
189 * Flush the input buffer. Called when the line discipline is
190 * being closed, when the tty layer wants the buffer flushed (eg
191 * at hangup) or when the N_TTY line discipline internally has to
192 * clean the pending queue (for example some signals).
193 *
194 * Locking: ctrl_lock, read_lock.
195 */
196
197static void n_tty_flush_buffer(struct tty_struct *tty)
198{
199 unsigned long flags;
200 /* clear everything and unthrottle the driver */
201 reset_buffer_flags(tty);
202
203 if (!tty->link)
204 return;
205
206 spin_lock_irqsave(&tty->ctrl_lock, flags);
207 if (tty->link->packet) {
208 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
209 wake_up_interruptible(&tty->link->read_wait);
210 }
211 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
212}
213
214/**
215 * n_tty_chars_in_buffer - report available bytes
216 * @tty: tty device
217 *
218 * Report the number of characters buffered to be delivered to user
219 * at this instant in time.
220 *
221 * Locking: read_lock
222 */
223
224static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
225{
226 unsigned long flags;
227 ssize_t n = 0;
228
229 spin_lock_irqsave(&tty->read_lock, flags);
230 if (!tty->icanon) {
231 n = tty->read_cnt;
232 } else if (tty->canon_data) {
233 n = (tty->canon_head > tty->read_tail) ?
234 tty->canon_head - tty->read_tail :
235 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
236 }
237 spin_unlock_irqrestore(&tty->read_lock, flags);
238 return n;
239}
240
241/**
242 * is_utf8_continuation - utf8 multibyte check
243 * @c: byte to check
244 *
245 * Returns true if the utf8 character 'c' is a multibyte continuation
246 * character. We use this to correctly compute the on screen size
247 * of the character when printing
248 */
249
250static inline int is_utf8_continuation(unsigned char c)
251{
252 return (c & 0xc0) == 0x80;
253}
254
255/**
256 * is_continuation - multibyte check
257 * @c: byte to check
258 *
259 * Returns true if the utf8 character 'c' is a multibyte continuation
260 * character and the terminal is in unicode mode.
261 */
262
263static inline int is_continuation(unsigned char c, struct tty_struct *tty)
264{
265 return I_IUTF8(tty) && is_utf8_continuation(c);
266}
267
268/**
269 * do_output_char - output one character
270 * @c: character (or partial unicode symbol)
271 * @tty: terminal device
272 * @space: space available in tty driver write buffer
273 *
274 * This is a helper function that handles one output character
275 * (including special characters like TAB, CR, LF, etc.),
276 * doing OPOST processing and putting the results in the
277 * tty driver's write buffer.
278 *
279 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
280 * and NLDLY. They simply aren't relevant in the world today.
281 * If you ever need them, add them here.
282 *
283 * Returns the number of bytes of buffer space used or -1 if
284 * no space left.
285 *
286 * Locking: should be called under the output_lock to protect
287 * the column state and space left in the buffer
288 */
289
290static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
291{
292 int spaces;
293
294 if (!space)
295 return -1;
296
297 switch (c) {
298 case '\n':
299 if (O_ONLRET(tty))
300 tty->column = 0;
301 if (O_ONLCR(tty)) {
302 if (space < 2)
303 return -1;
304 tty->canon_column = tty->column = 0;
305 tty->ops->write(tty, "\r\n", 2);
306 return 2;
307 }
308 tty->canon_column = tty->column;
309 break;
310 case '\r':
311 if (O_ONOCR(tty) && tty->column == 0)
312 return 0;
313 if (O_OCRNL(tty)) {
314 c = '\n';
315 if (O_ONLRET(tty))
316 tty->canon_column = tty->column = 0;
317 break;
318 }
319 tty->canon_column = tty->column = 0;
320 break;
321 case '\t':
322 spaces = 8 - (tty->column & 7);
323 if (O_TABDLY(tty) == XTABS) {
324 if (space < spaces)
325 return -1;
326 tty->column += spaces;
327 tty->ops->write(tty, " ", spaces);
328 return spaces;
329 }
330 tty->column += spaces;
331 break;
332 case '\b':
333 if (tty->column > 0)
334 tty->column--;
335 break;
336 default:
337 if (!iscntrl(c)) {
338 if (O_OLCUC(tty))
339 c = toupper(c);
340 if (!is_continuation(c, tty))
341 tty->column++;
342 }
343 break;
344 }
345
346 tty_put_char(tty, c);
347 return 1;
348}
349
350/**
351 * process_output - output post processor
352 * @c: character (or partial unicode symbol)
353 * @tty: terminal device
354 *
355 * Output one character with OPOST processing.
356 * Returns -1 when the output device is full and the character
357 * must be retried.
358 *
359 * Locking: output_lock to protect column state and space left
360 * (also, this is called from n_tty_write under the
361 * tty layer write lock)
362 */
363
364static int process_output(unsigned char c, struct tty_struct *tty)
365{
366 int space, retval;
367
368 mutex_lock(&tty->output_lock);
369
370 space = tty_write_room(tty);
371 retval = do_output_char(c, tty, space);
372
373 mutex_unlock(&tty->output_lock);
374 if (retval < 0)
375 return -1;
376 else
377 return 0;
378}
379
380/**
381 * process_output_block - block post processor
382 * @tty: terminal device
383 * @buf: character buffer
384 * @nr: number of bytes to output
385 *
386 * Output a block of characters with OPOST processing.
387 * Returns the number of characters output.
388 *
389 * This path is used to speed up block console writes, among other
390 * things when processing blocks of output data. It handles only
391 * the simple cases normally found and helps to generate blocks of
392 * symbols for the console driver and thus improve performance.
393 *
394 * Locking: output_lock to protect column state and space left
395 * (also, this is called from n_tty_write under the
396 * tty layer write lock)
397 */
398
399static ssize_t process_output_block(struct tty_struct *tty,
400 const unsigned char *buf, unsigned int nr)
401{
402 int space;
403 int i;
404 const unsigned char *cp;
405
406 mutex_lock(&tty->output_lock);
407
408 space = tty_write_room(tty);
409 if (!space) {
410 mutex_unlock(&tty->output_lock);
411 return 0;
412 }
413 if (nr > space)
414 nr = space;
415
416 for (i = 0, cp = buf; i < nr; i++, cp++) {
417 unsigned char c = *cp;
418
419 switch (c) {
420 case '\n':
421 if (O_ONLRET(tty))
422 tty->column = 0;
423 if (O_ONLCR(tty))
424 goto break_out;
425 tty->canon_column = tty->column;
426 break;
427 case '\r':
428 if (O_ONOCR(tty) && tty->column == 0)
429 goto break_out;
430 if (O_OCRNL(tty))
431 goto break_out;
432 tty->canon_column = tty->column = 0;
433 break;
434 case '\t':
435 goto break_out;
436 case '\b':
437 if (tty->column > 0)
438 tty->column--;
439 break;
440 default:
441 if (!iscntrl(c)) {
442 if (O_OLCUC(tty))
443 goto break_out;
444 if (!is_continuation(c, tty))
445 tty->column++;
446 }
447 break;
448 }
449 }
450break_out:
451 i = tty->ops->write(tty, buf, i);
452
453 mutex_unlock(&tty->output_lock);
454 return i;
455}
456
457/**
458 * process_echoes - write pending echo characters
459 * @tty: terminal device
460 *
461 * Write previously buffered echo (and other ldisc-generated)
462 * characters to the tty.
463 *
464 * Characters generated by the ldisc (including echoes) need to
465 * be buffered because the driver's write buffer can fill during
466 * heavy program output. Echoing straight to the driver will
467 * often fail under these conditions, causing lost characters and
468 * resulting mismatches of ldisc state information.
469 *
470 * Since the ldisc state must represent the characters actually sent
471 * to the driver at the time of the write, operations like certain
472 * changes in column state are also saved in the buffer and executed
473 * here.
474 *
475 * A circular fifo buffer is used so that the most recent characters
476 * are prioritized. Also, when control characters are echoed with a
477 * prefixed "^", the pair is treated atomically and thus not separated.
478 *
479 * Locking: output_lock to protect column state and space left,
480 * echo_lock to protect the echo buffer
481 */
482
483static void process_echoes(struct tty_struct *tty)
484{
485 int space, nr;
486 unsigned char c;
487 unsigned char *cp, *buf_end;
488
489 if (!tty->echo_cnt)
490 return;
491
492 mutex_lock(&tty->output_lock);
493 mutex_lock(&tty->echo_lock);
494
495 space = tty_write_room(tty);
496
497 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
498 cp = tty->echo_buf + tty->echo_pos;
499 nr = tty->echo_cnt;
500 while (nr > 0) {
501 c = *cp;
502 if (c == ECHO_OP_START) {
503 unsigned char op;
504 unsigned char *opp;
505 int no_space_left = 0;
506
507 /*
508 * If the buffer byte is the start of a multi-byte
509 * operation, get the next byte, which is either the
510 * op code or a control character value.
511 */
512 opp = cp + 1;
513 if (opp == buf_end)
514 opp -= N_TTY_BUF_SIZE;
515 op = *opp;
516
517 switch (op) {
518 unsigned int num_chars, num_bs;
519
520 case ECHO_OP_ERASE_TAB:
521 if (++opp == buf_end)
522 opp -= N_TTY_BUF_SIZE;
523 num_chars = *opp;
524
525 /*
526 * Determine how many columns to go back
527 * in order to erase the tab.
528 * This depends on the number of columns
529 * used by other characters within the tab
530 * area. If this (modulo 8) count is from
531 * the start of input rather than from a
532 * previous tab, we offset by canon column.
533 * Otherwise, tab spacing is normal.
534 */
535 if (!(num_chars & 0x80))
536 num_chars += tty->canon_column;
537 num_bs = 8 - (num_chars & 7);
538
539 if (num_bs > space) {
540 no_space_left = 1;
541 break;
542 }
543 space -= num_bs;
544 while (num_bs--) {
545 tty_put_char(tty, '\b');
546 if (tty->column > 0)
547 tty->column--;
548 }
549 cp += 3;
550 nr -= 3;
551 break;
552
553 case ECHO_OP_SET_CANON_COL:
554 tty->canon_column = tty->column;
555 cp += 2;
556 nr -= 2;
557 break;
558
559 case ECHO_OP_MOVE_BACK_COL:
560 if (tty->column > 0)
561 tty->column--;
562 cp += 2;
563 nr -= 2;
564 break;
565
566 case ECHO_OP_START:
567 /* This is an escaped echo op start code */
568 if (!space) {
569 no_space_left = 1;
570 break;
571 }
572 tty_put_char(tty, ECHO_OP_START);
573 tty->column++;
574 space--;
575 cp += 2;
576 nr -= 2;
577 break;
578
579 default:
580 /*
581 * If the op is not a special byte code,
582 * it is a ctrl char tagged to be echoed
583 * as "^X" (where X is the letter
584 * representing the control char).
585 * Note that we must ensure there is
586 * enough space for the whole ctrl pair.
587 *
588 */
589 if (space < 2) {
590 no_space_left = 1;
591 break;
592 }
593 tty_put_char(tty, '^');
594 tty_put_char(tty, op ^ 0100);
595 tty->column += 2;
596 space -= 2;
597 cp += 2;
598 nr -= 2;
599 }
600
601 if (no_space_left)
602 break;
603 } else {
604 if (O_OPOST(tty) &&
605 !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
606 int retval = do_output_char(c, tty, space);
607 if (retval < 0)
608 break;
609 space -= retval;
610 } else {
611 if (!space)
612 break;
613 tty_put_char(tty, c);
614 space -= 1;
615 }
616 cp += 1;
617 nr -= 1;
618 }
619
620 /* When end of circular buffer reached, wrap around */
621 if (cp >= buf_end)
622 cp -= N_TTY_BUF_SIZE;
623 }
624
625 if (nr == 0) {
626 tty->echo_pos = 0;
627 tty->echo_cnt = 0;
628 tty->echo_overrun = 0;
629 } else {
630 int num_processed = tty->echo_cnt - nr;
631 tty->echo_pos += num_processed;
632 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
633 tty->echo_cnt = nr;
634 if (num_processed > 0)
635 tty->echo_overrun = 0;
636 }
637
638 mutex_unlock(&tty->echo_lock);
639 mutex_unlock(&tty->output_lock);
640
641 if (tty->ops->flush_chars)
642 tty->ops->flush_chars(tty);
643}
644
645/**
646 * add_echo_byte - add a byte to the echo buffer
647 * @c: unicode byte to echo
648 * @tty: terminal device
649 *
650 * Add a character or operation byte to the echo buffer.
651 *
652 * Should be called under the echo lock to protect the echo buffer.
653 */
654
655static void add_echo_byte(unsigned char c, struct tty_struct *tty)
656{
657 int new_byte_pos;
658
659 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
660 /* Circular buffer is already at capacity */
661 new_byte_pos = tty->echo_pos;
662
663 /*
664 * Since the buffer start position needs to be advanced,
665 * be sure to step by a whole operation byte group.
666 */
667 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
668 if (tty->echo_buf[(tty->echo_pos + 1) &
669 (N_TTY_BUF_SIZE - 1)] ==
670 ECHO_OP_ERASE_TAB) {
671 tty->echo_pos += 3;
672 tty->echo_cnt -= 2;
673 } else {
674 tty->echo_pos += 2;
675 tty->echo_cnt -= 1;
676 }
677 } else {
678 tty->echo_pos++;
679 }
680 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
681
682 tty->echo_overrun = 1;
683 } else {
684 new_byte_pos = tty->echo_pos + tty->echo_cnt;
685 new_byte_pos &= N_TTY_BUF_SIZE - 1;
686 tty->echo_cnt++;
687 }
688
689 tty->echo_buf[new_byte_pos] = c;
690}
691
692/**
693 * echo_move_back_col - add operation to move back a column
694 * @tty: terminal device
695 *
696 * Add an operation to the echo buffer to move back one column.
697 *
698 * Locking: echo_lock to protect the echo buffer
699 */
700
701static void echo_move_back_col(struct tty_struct *tty)
702{
703 mutex_lock(&tty->echo_lock);
704
705 add_echo_byte(ECHO_OP_START, tty);
706 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
707
708 mutex_unlock(&tty->echo_lock);
709}
710
711/**
712 * echo_set_canon_col - add operation to set the canon column
713 * @tty: terminal device
714 *
715 * Add an operation to the echo buffer to set the canon column
716 * to the current column.
717 *
718 * Locking: echo_lock to protect the echo buffer
719 */
720
721static void echo_set_canon_col(struct tty_struct *tty)
722{
723 mutex_lock(&tty->echo_lock);
724
725 add_echo_byte(ECHO_OP_START, tty);
726 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
727
728 mutex_unlock(&tty->echo_lock);
729}
730
731/**
732 * echo_erase_tab - add operation to erase a tab
733 * @num_chars: number of character columns already used
734 * @after_tab: true if num_chars starts after a previous tab
735 * @tty: terminal device
736 *
737 * Add an operation to the echo buffer to erase a tab.
738 *
739 * Called by the eraser function, which knows how many character
740 * columns have been used since either a previous tab or the start
741 * of input. This information will be used later, along with
742 * canon column (if applicable), to go back the correct number
743 * of columns.
744 *
745 * Locking: echo_lock to protect the echo buffer
746 */
747
748static void echo_erase_tab(unsigned int num_chars, int after_tab,
749 struct tty_struct *tty)
750{
751 mutex_lock(&tty->echo_lock);
752
753 add_echo_byte(ECHO_OP_START, tty);
754 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
755
756 /* We only need to know this modulo 8 (tab spacing) */
757 num_chars &= 7;
758
759 /* Set the high bit as a flag if num_chars is after a previous tab */
760 if (after_tab)
761 num_chars |= 0x80;
762
763 add_echo_byte(num_chars, tty);
764
765 mutex_unlock(&tty->echo_lock);
766}
767
768/**
769 * echo_char_raw - echo a character raw
770 * @c: unicode byte to echo
771 * @tty: terminal device
772 *
773 * Echo user input back onto the screen. This must be called only when
774 * L_ECHO(tty) is true. Called from the driver receive_buf path.
775 *
776 * This variant does not treat control characters specially.
777 *
778 * Locking: echo_lock to protect the echo buffer
779 */
780
781static void echo_char_raw(unsigned char c, struct tty_struct *tty)
782{
783 mutex_lock(&tty->echo_lock);
784
785 if (c == ECHO_OP_START) {
786 add_echo_byte(ECHO_OP_START, tty);
787 add_echo_byte(ECHO_OP_START, tty);
788 } else {
789 add_echo_byte(c, tty);
790 }
791
792 mutex_unlock(&tty->echo_lock);
793}
794
795/**
796 * echo_char - echo a character
797 * @c: unicode byte to echo
798 * @tty: terminal device
799 *
800 * Echo user input back onto the screen. This must be called only when
801 * L_ECHO(tty) is true. Called from the driver receive_buf path.
802 *
803 * This variant tags control characters to be echoed as "^X"
804 * (where X is the letter representing the control char).
805 *
806 * Locking: echo_lock to protect the echo buffer
807 */
808
809static void echo_char(unsigned char c, struct tty_struct *tty)
810{
811 mutex_lock(&tty->echo_lock);
812
813 if (c == ECHO_OP_START) {
814 add_echo_byte(ECHO_OP_START, tty);
815 add_echo_byte(ECHO_OP_START, tty);
816 } else {
817 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
818 add_echo_byte(ECHO_OP_START, tty);
819 add_echo_byte(c, tty);
820 }
821
822 mutex_unlock(&tty->echo_lock);
823}
824
825/**
826 * finish_erasing - complete erase
827 * @tty: tty doing the erase
828 */
829
830static inline void finish_erasing(struct tty_struct *tty)
831{
832 if (tty->erasing) {
833 echo_char_raw('/', tty);
834 tty->erasing = 0;
835 }
836}
837
838/**
839 * eraser - handle erase function
840 * @c: character input
841 * @tty: terminal device
842 *
843 * Perform erase and necessary output when an erase character is
844 * present in the stream from the driver layer. Handles the complexities
845 * of UTF-8 multibyte symbols.
846 *
847 * Locking: read_lock for tty buffers
848 */
849
850static void eraser(unsigned char c, struct tty_struct *tty)
851{
852 enum { ERASE, WERASE, KILL } kill_type;
853 int head, seen_alnums, cnt;
854 unsigned long flags;
855
856 /* FIXME: locking needed ? */
857 if (tty->read_head == tty->canon_head) {
858 /* process_output('\a', tty); */ /* what do you think? */
859 return;
860 }
861 if (c == ERASE_CHAR(tty))
862 kill_type = ERASE;
863 else if (c == WERASE_CHAR(tty))
864 kill_type = WERASE;
865 else {
866 if (!L_ECHO(tty)) {
867 spin_lock_irqsave(&tty->read_lock, flags);
868 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
869 (N_TTY_BUF_SIZE - 1));
870 tty->read_head = tty->canon_head;
871 spin_unlock_irqrestore(&tty->read_lock, flags);
872 return;
873 }
874 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
875 spin_lock_irqsave(&tty->read_lock, flags);
876 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
877 (N_TTY_BUF_SIZE - 1));
878 tty->read_head = tty->canon_head;
879 spin_unlock_irqrestore(&tty->read_lock, flags);
880 finish_erasing(tty);
881 echo_char(KILL_CHAR(tty), tty);
882 /* Add a newline if ECHOK is on and ECHOKE is off. */
883 if (L_ECHOK(tty))
884 echo_char_raw('\n', tty);
885 return;
886 }
887 kill_type = KILL;
888 }
889
890 seen_alnums = 0;
891 /* FIXME: Locking ?? */
892 while (tty->read_head != tty->canon_head) {
893 head = tty->read_head;
894
895 /* erase a single possibly multibyte character */
896 do {
897 head = (head - 1) & (N_TTY_BUF_SIZE-1);
898 c = tty->read_buf[head];
899 } while (is_continuation(c, tty) && head != tty->canon_head);
900
901 /* do not partially erase */
902 if (is_continuation(c, tty))
903 break;
904
905 if (kill_type == WERASE) {
906 /* Equivalent to BSD's ALTWERASE. */
907 if (isalnum(c) || c == '_')
908 seen_alnums++;
909 else if (seen_alnums)
910 break;
911 }
912 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
913 spin_lock_irqsave(&tty->read_lock, flags);
914 tty->read_head = head;
915 tty->read_cnt -= cnt;
916 spin_unlock_irqrestore(&tty->read_lock, flags);
917 if (L_ECHO(tty)) {
918 if (L_ECHOPRT(tty)) {
919 if (!tty->erasing) {
920 echo_char_raw('\\', tty);
921 tty->erasing = 1;
922 }
923 /* if cnt > 1, output a multi-byte character */
924 echo_char(c, tty);
925 while (--cnt > 0) {
926 head = (head+1) & (N_TTY_BUF_SIZE-1);
927 echo_char_raw(tty->read_buf[head], tty);
928 echo_move_back_col(tty);
929 }
930 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
931 echo_char(ERASE_CHAR(tty), tty);
932 } else if (c == '\t') {
933 unsigned int num_chars = 0;
934 int after_tab = 0;
935 unsigned long tail = tty->read_head;
936
937 /*
938 * Count the columns used for characters
939 * since the start of input or after a
940 * previous tab.
941 * This info is used to go back the correct
942 * number of columns.
943 */
944 while (tail != tty->canon_head) {
945 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
946 c = tty->read_buf[tail];
947 if (c == '\t') {
948 after_tab = 1;
949 break;
950 } else if (iscntrl(c)) {
951 if (L_ECHOCTL(tty))
952 num_chars += 2;
953 } else if (!is_continuation(c, tty)) {
954 num_chars++;
955 }
956 }
957 echo_erase_tab(num_chars, after_tab, tty);
958 } else {
959 if (iscntrl(c) && L_ECHOCTL(tty)) {
960 echo_char_raw('\b', tty);
961 echo_char_raw(' ', tty);
962 echo_char_raw('\b', tty);
963 }
964 if (!iscntrl(c) || L_ECHOCTL(tty)) {
965 echo_char_raw('\b', tty);
966 echo_char_raw(' ', tty);
967 echo_char_raw('\b', tty);
968 }
969 }
970 }
971 if (kill_type == ERASE)
972 break;
973 }
974 if (tty->read_head == tty->canon_head && L_ECHO(tty))
975 finish_erasing(tty);
976}
977
978/**
979 * isig - handle the ISIG optio
980 * @sig: signal
981 * @tty: terminal
982 * @flush: force flush
983 *
984 * Called when a signal is being sent due to terminal input. This
985 * may caus terminal flushing to take place according to the termios
986 * settings and character used. Called from the driver receive_buf
987 * path so serialized.
988 *
989 * Locking: ctrl_lock, read_lock (both via flush buffer)
990 */
991
992static inline void isig(int sig, struct tty_struct *tty, int flush)
993{
994 if (tty->pgrp)
995 kill_pgrp(tty->pgrp, sig, 1);
996 if (flush || !L_NOFLSH(tty)) {
997 n_tty_flush_buffer(tty);
998 tty_driver_flush_buffer(tty);
999 }
1000}
1001
1002/**
1003 * n_tty_receive_break - handle break
1004 * @tty: terminal
1005 *
1006 * An RS232 break event has been hit in the incoming bitstream. This
1007 * can cause a variety of events depending upon the termios settings.
1008 *
1009 * Called from the receive_buf path so single threaded.
1010 */
1011
1012static inline void n_tty_receive_break(struct tty_struct *tty)
1013{
1014 if (I_IGNBRK(tty))
1015 return;
1016 if (I_BRKINT(tty)) {
1017 isig(SIGINT, tty, 1);
1018 return;
1019 }
1020 if (I_PARMRK(tty)) {
1021 put_tty_queue('\377', tty);
1022 put_tty_queue('\0', tty);
1023 }
1024 put_tty_queue('\0', tty);
1025 wake_up_interruptible(&tty->read_wait);
1026}
1027
1028/**
1029 * n_tty_receive_overrun - handle overrun reporting
1030 * @tty: terminal
1031 *
1032 * Data arrived faster than we could process it. While the tty
1033 * driver has flagged this the bits that were missed are gone
1034 * forever.
1035 *
1036 * Called from the receive_buf path so single threaded. Does not
1037 * need locking as num_overrun and overrun_time are function
1038 * private.
1039 */
1040
1041static inline void n_tty_receive_overrun(struct tty_struct *tty)
1042{
1043 char buf[64];
1044
1045 tty->num_overrun++;
1046 if (time_before(tty->overrun_time, jiffies - HZ) ||
1047 time_after(tty->overrun_time, jiffies)) {
1048 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1049 tty_name(tty, buf),
1050 tty->num_overrun);
1051 tty->overrun_time = jiffies;
1052 tty->num_overrun = 0;
1053 }
1054}
1055
1056/**
1057 * n_tty_receive_parity_error - error notifier
1058 * @tty: terminal device
1059 * @c: character
1060 *
1061 * Process a parity error and queue the right data to indicate
1062 * the error case if necessary. Locking as per n_tty_receive_buf.
1063 */
1064static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1065 unsigned char c)
1066{
1067 if (I_IGNPAR(tty))
1068 return;
1069 if (I_PARMRK(tty)) {
1070 put_tty_queue('\377', tty);
1071 put_tty_queue('\0', tty);
1072 put_tty_queue(c, tty);
1073 } else if (I_INPCK(tty))
1074 put_tty_queue('\0', tty);
1075 else
1076 put_tty_queue(c, tty);
1077 wake_up_interruptible(&tty->read_wait);
1078}
1079
1080/**
1081 * n_tty_receive_char - perform processing
1082 * @tty: terminal device
1083 * @c: character
1084 *
1085 * Process an individual character of input received from the driver.
1086 * This is serialized with respect to itself by the rules for the
1087 * driver above.
1088 */
1089
1090static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1091{
1092 unsigned long flags;
1093 int parmrk;
1094
1095 if (tty->raw) {
1096 put_tty_queue(c, tty);
1097 return;
1098 }
1099
1100 if (I_ISTRIP(tty))
1101 c &= 0x7f;
1102 if (I_IUCLC(tty) && L_IEXTEN(tty))
1103 c = tolower(c);
1104
1105 if (L_EXTPROC(tty)) {
1106 put_tty_queue(c, tty);
1107 return;
1108 }
1109
1110 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1111 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1112 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1113 start_tty(tty);
1114 process_echoes(tty);
1115 }
1116
1117 if (tty->closing) {
1118 if (I_IXON(tty)) {
1119 if (c == START_CHAR(tty)) {
1120 start_tty(tty);
1121 process_echoes(tty);
1122 } else if (c == STOP_CHAR(tty))
1123 stop_tty(tty);
1124 }
1125 return;
1126 }
1127
1128 /*
1129 * If the previous character was LNEXT, or we know that this
1130 * character is not one of the characters that we'll have to
1131 * handle specially, do shortcut processing to speed things
1132 * up.
1133 */
1134 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1135 tty->lnext = 0;
1136 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1137 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1138 /* beep if no space */
1139 if (L_ECHO(tty))
1140 process_output('\a', tty);
1141 return;
1142 }
1143 if (L_ECHO(tty)) {
1144 finish_erasing(tty);
1145 /* Record the column of first canon char. */
1146 if (tty->canon_head == tty->read_head)
1147 echo_set_canon_col(tty);
1148 echo_char(c, tty);
1149 process_echoes(tty);
1150 }
1151 if (parmrk)
1152 put_tty_queue(c, tty);
1153 put_tty_queue(c, tty);
1154 return;
1155 }
1156
1157 if (I_IXON(tty)) {
1158 if (c == START_CHAR(tty)) {
1159 start_tty(tty);
1160 process_echoes(tty);
1161 return;
1162 }
1163 if (c == STOP_CHAR(tty)) {
1164 stop_tty(tty);
1165 return;
1166 }
1167 }
1168
1169 if (L_ISIG(tty)) {
1170 int signal;
1171 signal = SIGINT;
1172 if (c == INTR_CHAR(tty))
1173 goto send_signal;
1174 signal = SIGQUIT;
1175 if (c == QUIT_CHAR(tty))
1176 goto send_signal;
1177 signal = SIGTSTP;
1178 if (c == SUSP_CHAR(tty)) {
1179send_signal:
1180 /*
1181 * Note that we do not use isig() here because we want
1182 * the order to be:
1183 * 1) flush, 2) echo, 3) signal
1184 */
1185 if (!L_NOFLSH(tty)) {
1186 n_tty_flush_buffer(tty);
1187 tty_driver_flush_buffer(tty);
1188 }
1189 if (I_IXON(tty))
1190 start_tty(tty);
1191 if (L_ECHO(tty)) {
1192 echo_char(c, tty);
1193 process_echoes(tty);
1194 }
1195 if (tty->pgrp)
1196 kill_pgrp(tty->pgrp, signal, 1);
1197 return;
1198 }
1199 }
1200
1201 if (c == '\r') {
1202 if (I_IGNCR(tty))
1203 return;
1204 if (I_ICRNL(tty))
1205 c = '\n';
1206 } else if (c == '\n' && I_INLCR(tty))
1207 c = '\r';
1208
1209 if (tty->icanon) {
1210 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1211 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1212 eraser(c, tty);
1213 process_echoes(tty);
1214 return;
1215 }
1216 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1217 tty->lnext = 1;
1218 if (L_ECHO(tty)) {
1219 finish_erasing(tty);
1220 if (L_ECHOCTL(tty)) {
1221 echo_char_raw('^', tty);
1222 echo_char_raw('\b', tty);
1223 process_echoes(tty);
1224 }
1225 }
1226 return;
1227 }
1228 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1229 L_IEXTEN(tty)) {
1230 unsigned long tail = tty->canon_head;
1231
1232 finish_erasing(tty);
1233 echo_char(c, tty);
1234 echo_char_raw('\n', tty);
1235 while (tail != tty->read_head) {
1236 echo_char(tty->read_buf[tail], tty);
1237 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1238 }
1239 process_echoes(tty);
1240 return;
1241 }
1242 if (c == '\n') {
1243 if (tty->read_cnt >= N_TTY_BUF_SIZE) {
1244 if (L_ECHO(tty))
1245 process_output('\a', tty);
1246 return;
1247 }
1248 if (L_ECHO(tty) || L_ECHONL(tty)) {
1249 echo_char_raw('\n', tty);
1250 process_echoes(tty);
1251 }
1252 goto handle_newline;
1253 }
1254 if (c == EOF_CHAR(tty)) {
1255 if (tty->read_cnt >= N_TTY_BUF_SIZE)
1256 return;
1257 if (tty->canon_head != tty->read_head)
1258 set_bit(TTY_PUSH, &tty->flags);
1259 c = __DISABLED_CHAR;
1260 goto handle_newline;
1261 }
1262 if ((c == EOL_CHAR(tty)) ||
1263 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1264 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1265 ? 1 : 0;
1266 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
1267 if (L_ECHO(tty))
1268 process_output('\a', tty);
1269 return;
1270 }
1271 /*
1272 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1273 */
1274 if (L_ECHO(tty)) {
1275 /* Record the column of first canon char. */
1276 if (tty->canon_head == tty->read_head)
1277 echo_set_canon_col(tty);
1278 echo_char(c, tty);
1279 process_echoes(tty);
1280 }
1281 /*
1282 * XXX does PARMRK doubling happen for
1283 * EOL_CHAR and EOL2_CHAR?
1284 */
1285 if (parmrk)
1286 put_tty_queue(c, tty);
1287
1288handle_newline:
1289 spin_lock_irqsave(&tty->read_lock, flags);
1290 set_bit(tty->read_head, tty->read_flags);
1291 put_tty_queue_nolock(c, tty);
1292 tty->canon_head = tty->read_head;
1293 tty->canon_data++;
1294 spin_unlock_irqrestore(&tty->read_lock, flags);
1295 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1296 if (waitqueue_active(&tty->read_wait))
1297 wake_up_interruptible(&tty->read_wait);
1298 return;
1299 }
1300 }
1301
1302 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1303 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1304 /* beep if no space */
1305 if (L_ECHO(tty))
1306 process_output('\a', tty);
1307 return;
1308 }
1309 if (L_ECHO(tty)) {
1310 finish_erasing(tty);
1311 if (c == '\n')
1312 echo_char_raw('\n', tty);
1313 else {
1314 /* Record the column of first canon char. */
1315 if (tty->canon_head == tty->read_head)
1316 echo_set_canon_col(tty);
1317 echo_char(c, tty);
1318 }
1319 process_echoes(tty);
1320 }
1321
1322 if (parmrk)
1323 put_tty_queue(c, tty);
1324
1325 put_tty_queue(c, tty);
1326}
1327
1328
1329/**
1330 * n_tty_write_wakeup - asynchronous I/O notifier
1331 * @tty: tty device
1332 *
1333 * Required for the ptys, serial driver etc. since processes
1334 * that attach themselves to the master and rely on ASYNC
1335 * IO must be woken up
1336 */
1337
1338static void n_tty_write_wakeup(struct tty_struct *tty)
1339{
1340 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
1341 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1342}
1343
1344/**
1345 * n_tty_receive_buf - data receive
1346 * @tty: terminal device
1347 * @cp: buffer
1348 * @fp: flag buffer
1349 * @count: characters
1350 *
1351 * Called by the terminal driver when a block of characters has
1352 * been received. This function must be called from soft contexts
1353 * not from interrupt context. The driver is responsible for making
1354 * calls one at a time and in order (or using flush_to_ldisc)
1355 */
1356
1357static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1358 char *fp, int count)
1359{
1360 const unsigned char *p;
1361 char *f, flags = TTY_NORMAL;
1362 int i;
1363 char buf[64];
1364 unsigned long cpuflags;
1365
1366 if (!tty->read_buf)
1367 return;
1368
1369 if (tty->real_raw) {
1370 spin_lock_irqsave(&tty->read_lock, cpuflags);
1371 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1372 N_TTY_BUF_SIZE - tty->read_head);
1373 i = min(count, i);
1374 memcpy(tty->read_buf + tty->read_head, cp, i);
1375 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1376 tty->read_cnt += i;
1377 cp += i;
1378 count -= i;
1379
1380 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1381 N_TTY_BUF_SIZE - tty->read_head);
1382 i = min(count, i);
1383 memcpy(tty->read_buf + tty->read_head, cp, i);
1384 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1385 tty->read_cnt += i;
1386 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1387 } else {
1388 for (i = count, p = cp, f = fp; i; i--, p++) {
1389 if (f)
1390 flags = *f++;
1391 switch (flags) {
1392 case TTY_NORMAL:
1393 n_tty_receive_char(tty, *p);
1394 break;
1395 case TTY_BREAK:
1396 n_tty_receive_break(tty);
1397 break;
1398 case TTY_PARITY:
1399 case TTY_FRAME:
1400 n_tty_receive_parity_error(tty, *p);
1401 break;
1402 case TTY_OVERRUN:
1403 n_tty_receive_overrun(tty);
1404 break;
1405 default:
1406 printk(KERN_ERR "%s: unknown flag %d\n",
1407 tty_name(tty, buf), flags);
1408 break;
1409 }
1410 }
1411 if (tty->ops->flush_chars)
1412 tty->ops->flush_chars(tty);
1413 }
1414
1415 n_tty_set_room(tty);
1416
1417 if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
1418 L_EXTPROC(tty)) {
1419 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1420 if (waitqueue_active(&tty->read_wait))
1421 wake_up_interruptible(&tty->read_wait);
1422 }
1423
1424 /*
1425 * Check the remaining room for the input canonicalization
1426 * mode. We don't want to throttle the driver if we're in
1427 * canonical mode and don't have a newline yet!
1428 */
1429 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1430 tty_throttle(tty);
1431}
1432
1433int is_ignored(int sig)
1434{
1435 return (sigismember(&current->blocked, sig) ||
1436 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1437}
1438
1439/**
1440 * n_tty_set_termios - termios data changed
1441 * @tty: terminal
1442 * @old: previous data
1443 *
1444 * Called by the tty layer when the user changes termios flags so
1445 * that the line discipline can plan ahead. This function cannot sleep
1446 * and is protected from re-entry by the tty layer. The user is
1447 * guaranteed that this function will not be re-entered or in progress
1448 * when the ldisc is closed.
1449 *
1450 * Locking: Caller holds tty->termios_mutex
1451 */
1452
1453static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1454{
1455 int canon_change = 1;
1456 BUG_ON(!tty);
1457
1458 if (old)
1459 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1460 if (canon_change) {
1461 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1462 tty->canon_head = tty->read_tail;
1463 tty->canon_data = 0;
1464 tty->erasing = 0;
1465 }
1466
1467 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1468 wake_up_interruptible(&tty->read_wait);
1469
1470 tty->icanon = (L_ICANON(tty) != 0);
1471 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1472 tty->raw = 1;
1473 tty->real_raw = 1;
1474 n_tty_set_room(tty);
1475 return;
1476 }
1477 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1478 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1479 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1480 I_PARMRK(tty)) {
1481 memset(tty->process_char_map, 0, 256/8);
1482
1483 if (I_IGNCR(tty) || I_ICRNL(tty))
1484 set_bit('\r', tty->process_char_map);
1485 if (I_INLCR(tty))
1486 set_bit('\n', tty->process_char_map);
1487
1488 if (L_ICANON(tty)) {
1489 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1490 set_bit(KILL_CHAR(tty), tty->process_char_map);
1491 set_bit(EOF_CHAR(tty), tty->process_char_map);
1492 set_bit('\n', tty->process_char_map);
1493 set_bit(EOL_CHAR(tty), tty->process_char_map);
1494 if (L_IEXTEN(tty)) {
1495 set_bit(WERASE_CHAR(tty),
1496 tty->process_char_map);
1497 set_bit(LNEXT_CHAR(tty),
1498 tty->process_char_map);
1499 set_bit(EOL2_CHAR(tty),
1500 tty->process_char_map);
1501 if (L_ECHO(tty))
1502 set_bit(REPRINT_CHAR(tty),
1503 tty->process_char_map);
1504 }
1505 }
1506 if (I_IXON(tty)) {
1507 set_bit(START_CHAR(tty), tty->process_char_map);
1508 set_bit(STOP_CHAR(tty), tty->process_char_map);
1509 }
1510 if (L_ISIG(tty)) {
1511 set_bit(INTR_CHAR(tty), tty->process_char_map);
1512 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1513 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1514 }
1515 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1516 tty->raw = 0;
1517 tty->real_raw = 0;
1518 } else {
1519 tty->raw = 1;
1520 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1521 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1522 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1523 tty->real_raw = 1;
1524 else
1525 tty->real_raw = 0;
1526 }
1527 n_tty_set_room(tty);
1528 /* The termios change make the tty ready for I/O */
1529 wake_up_interruptible(&tty->write_wait);
1530 wake_up_interruptible(&tty->read_wait);
1531}
1532
1533/**
1534 * n_tty_close - close the ldisc for this tty
1535 * @tty: device
1536 *
1537 * Called from the terminal layer when this line discipline is
1538 * being shut down, either because of a close or becsuse of a
1539 * discipline change. The function will not be called while other
1540 * ldisc methods are in progress.
1541 */
1542
1543static void n_tty_close(struct tty_struct *tty)
1544{
1545 n_tty_flush_buffer(tty);
1546 if (tty->read_buf) {
1547 kfree(tty->read_buf);
1548 tty->read_buf = NULL;
1549 }
1550 if (tty->echo_buf) {
1551 kfree(tty->echo_buf);
1552 tty->echo_buf = NULL;
1553 }
1554}
1555
1556/**
1557 * n_tty_open - open an ldisc
1558 * @tty: terminal to open
1559 *
1560 * Called when this line discipline is being attached to the
1561 * terminal device. Can sleep. Called serialized so that no
1562 * other events will occur in parallel. No further open will occur
1563 * until a close.
1564 */
1565
1566static int n_tty_open(struct tty_struct *tty)
1567{
1568 if (!tty)
1569 return -EINVAL;
1570
1571 /* These are ugly. Currently a malloc failure here can panic */
1572 if (!tty->read_buf) {
1573 tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1574 if (!tty->read_buf)
1575 return -ENOMEM;
1576 }
1577 if (!tty->echo_buf) {
1578 tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1579
1580 if (!tty->echo_buf)
1581 return -ENOMEM;
1582 }
1583 reset_buffer_flags(tty);
1584 tty->column = 0;
1585 n_tty_set_termios(tty, NULL);
1586 tty->minimum_to_wake = 1;
1587 tty->closing = 0;
1588 return 0;
1589}
1590
1591static inline int input_available_p(struct tty_struct *tty, int amt)
1592{
1593 tty_flush_to_ldisc(tty);
1594 if (tty->icanon && !L_EXTPROC(tty)) {
1595 if (tty->canon_data)
1596 return 1;
1597 } else if (tty->read_cnt >= (amt ? amt : 1))
1598 return 1;
1599
1600 return 0;
1601}
1602
1603/**
1604 * copy_from_read_buf - copy read data directly
1605 * @tty: terminal device
1606 * @b: user data
1607 * @nr: size of data
1608 *
1609 * Helper function to speed up n_tty_read. It is only called when
1610 * ICANON is off; it copies characters straight from the tty queue to
1611 * user space directly. It can be profitably called twice; once to
1612 * drain the space from the tail pointer to the (physical) end of the
1613 * buffer, and once to drain the space from the (physical) beginning of
1614 * the buffer to head pointer.
1615 *
1616 * Called under the tty->atomic_read_lock sem
1617 *
1618 */
1619
1620static int copy_from_read_buf(struct tty_struct *tty,
1621 unsigned char __user **b,
1622 size_t *nr)
1623
1624{
1625 int retval;
1626 size_t n;
1627 unsigned long flags;
1628
1629 retval = 0;
1630 spin_lock_irqsave(&tty->read_lock, flags);
1631 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1632 n = min(*nr, n);
1633 spin_unlock_irqrestore(&tty->read_lock, flags);
1634 if (n) {
1635 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1636 n -= retval;
1637 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1638 spin_lock_irqsave(&tty->read_lock, flags);
1639 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1640 tty->read_cnt -= n;
1641 /* Turn single EOF into zero-length read */
1642 if (L_EXTPROC(tty) && tty->icanon && n == 1) {
1643 if (!tty->read_cnt && (*b)[n-1] == EOF_CHAR(tty))
1644 n--;
1645 }
1646 spin_unlock_irqrestore(&tty->read_lock, flags);
1647 *b += n;
1648 *nr -= n;
1649 }
1650 return retval;
1651}
1652
1653extern ssize_t redirected_tty_write(struct file *, const char __user *,
1654 size_t, loff_t *);
1655
1656/**
1657 * job_control - check job control
1658 * @tty: tty
1659 * @file: file handle
1660 *
1661 * Perform job control management checks on this file/tty descriptor
1662 * and if appropriate send any needed signals and return a negative
1663 * error code if action should be taken.
1664 *
1665 * FIXME:
1666 * Locking: None - redirected write test is safe, testing
1667 * current->signal should possibly lock current->sighand
1668 * pgrp locking ?
1669 */
1670
1671static int job_control(struct tty_struct *tty, struct file *file)
1672{
1673 /* Job control check -- must be done at start and after
1674 every sleep (POSIX.1 7.1.1.4). */
1675 /* NOTE: not yet done after every sleep pending a thorough
1676 check of the logic of this change. -- jlc */
1677 /* don't stop on /dev/console */
1678 if (file->f_op->write != redirected_tty_write &&
1679 current->signal->tty == tty) {
1680 if (!tty->pgrp)
1681 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1682 else if (task_pgrp(current) != tty->pgrp) {
1683 if (is_ignored(SIGTTIN) ||
1684 is_current_pgrp_orphaned())
1685 return -EIO;
1686 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1687 set_thread_flag(TIF_SIGPENDING);
1688 return -ERESTARTSYS;
1689 }
1690 }
1691 return 0;
1692}
1693
1694
1695/**
1696 * n_tty_read - read function for tty
1697 * @tty: tty device
1698 * @file: file object
1699 * @buf: userspace buffer pointer
1700 * @nr: size of I/O
1701 *
1702 * Perform reads for the line discipline. We are guaranteed that the
1703 * line discipline will not be closed under us but we may get multiple
1704 * parallel readers and must handle this ourselves. We may also get
1705 * a hangup. Always called in user context, may sleep.
1706 *
1707 * This code must be sure never to sleep through a hangup.
1708 */
1709
1710static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1711 unsigned char __user *buf, size_t nr)
1712{
1713 unsigned char __user *b = buf;
1714 DECLARE_WAITQUEUE(wait, current);
1715 int c;
1716 int minimum, time;
1717 ssize_t retval = 0;
1718 ssize_t size;
1719 long timeout;
1720 unsigned long flags;
1721 int packet;
1722
1723do_it_again:
1724
1725 BUG_ON(!tty->read_buf);
1726
1727 c = job_control(tty, file);
1728 if (c < 0)
1729 return c;
1730
1731 minimum = time = 0;
1732 timeout = MAX_SCHEDULE_TIMEOUT;
1733 if (!tty->icanon) {
1734 time = (HZ / 10) * TIME_CHAR(tty);
1735 minimum = MIN_CHAR(tty);
1736 if (minimum) {
1737 if (time)
1738 tty->minimum_to_wake = 1;
1739 else if (!waitqueue_active(&tty->read_wait) ||
1740 (tty->minimum_to_wake > minimum))
1741 tty->minimum_to_wake = minimum;
1742 } else {
1743 timeout = 0;
1744 if (time) {
1745 timeout = time;
1746 time = 0;
1747 }
1748 tty->minimum_to_wake = minimum = 1;
1749 }
1750 }
1751
1752 /*
1753 * Internal serialization of reads.
1754 */
1755 if (file->f_flags & O_NONBLOCK) {
1756 if (!mutex_trylock(&tty->atomic_read_lock))
1757 return -EAGAIN;
1758 } else {
1759 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1760 return -ERESTARTSYS;
1761 }
1762 packet = tty->packet;
1763
1764 add_wait_queue(&tty->read_wait, &wait);
1765 while (nr) {
1766 /* First test for status change. */
1767 if (packet && tty->link->ctrl_status) {
1768 unsigned char cs;
1769 if (b != buf)
1770 break;
1771 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1772 cs = tty->link->ctrl_status;
1773 tty->link->ctrl_status = 0;
1774 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1775 if (tty_put_user(tty, cs, b++)) {
1776 retval = -EFAULT;
1777 b--;
1778 break;
1779 }
1780 nr--;
1781 break;
1782 }
1783 /* This statement must be first before checking for input
1784 so that any interrupt will set the state back to
1785 TASK_RUNNING. */
1786 set_current_state(TASK_INTERRUPTIBLE);
1787
1788 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1789 ((minimum - (b - buf)) >= 1))
1790 tty->minimum_to_wake = (minimum - (b - buf));
1791
1792 if (!input_available_p(tty, 0)) {
1793 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1794 retval = -EIO;
1795 break;
1796 }
1797 if (tty_hung_up_p(file))
1798 break;
1799 if (!timeout)
1800 break;
1801 if (file->f_flags & O_NONBLOCK) {
1802 retval = -EAGAIN;
1803 break;
1804 }
1805 if (signal_pending(current)) {
1806 retval = -ERESTARTSYS;
1807 break;
1808 }
1809 /* FIXME: does n_tty_set_room need locking ? */
1810 n_tty_set_room(tty);
1811 timeout = schedule_timeout(timeout);
1812 continue;
1813 }
1814 __set_current_state(TASK_RUNNING);
1815
1816 /* Deal with packet mode. */
1817 if (packet && b == buf) {
1818 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1819 retval = -EFAULT;
1820 b--;
1821 break;
1822 }
1823 nr--;
1824 }
1825
1826 if (tty->icanon && !L_EXTPROC(tty)) {
1827 /* N.B. avoid overrun if nr == 0 */
1828 while (nr && tty->read_cnt) {
1829 int eol;
1830
1831 eol = test_and_clear_bit(tty->read_tail,
1832 tty->read_flags);
1833 c = tty->read_buf[tty->read_tail];
1834 spin_lock_irqsave(&tty->read_lock, flags);
1835 tty->read_tail = ((tty->read_tail+1) &
1836 (N_TTY_BUF_SIZE-1));
1837 tty->read_cnt--;
1838 if (eol) {
1839 /* this test should be redundant:
1840 * we shouldn't be reading data if
1841 * canon_data is 0
1842 */
1843 if (--tty->canon_data < 0)
1844 tty->canon_data = 0;
1845 }
1846 spin_unlock_irqrestore(&tty->read_lock, flags);
1847
1848 if (!eol || (c != __DISABLED_CHAR)) {
1849 if (tty_put_user(tty, c, b++)) {
1850 retval = -EFAULT;
1851 b--;
1852 break;
1853 }
1854 nr--;
1855 }
1856 if (eol) {
1857 tty_audit_push(tty);
1858 break;
1859 }
1860 }
1861 if (retval)
1862 break;
1863 } else {
1864 int uncopied;
1865 /* The copy function takes the read lock and handles
1866 locking internally for this case */
1867 uncopied = copy_from_read_buf(tty, &b, &nr);
1868 uncopied += copy_from_read_buf(tty, &b, &nr);
1869 if (uncopied) {
1870 retval = -EFAULT;
1871 break;
1872 }
1873 }
1874
1875 /* If there is enough space in the read buffer now, let the
1876 * low-level driver know. We use n_tty_chars_in_buffer() to
1877 * check the buffer, as it now knows about canonical mode.
1878 * Otherwise, if the driver is throttled and the line is
1879 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1880 * we won't get any more characters.
1881 */
1882 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1883 n_tty_set_room(tty);
1884 check_unthrottle(tty);
1885 }
1886
1887 if (b - buf >= minimum)
1888 break;
1889 if (time)
1890 timeout = time;
1891 }
1892 mutex_unlock(&tty->atomic_read_lock);
1893 remove_wait_queue(&tty->read_wait, &wait);
1894
1895 if (!waitqueue_active(&tty->read_wait))
1896 tty->minimum_to_wake = minimum;
1897
1898 __set_current_state(TASK_RUNNING);
1899 size = b - buf;
1900 if (size) {
1901 retval = size;
1902 if (nr)
1903 clear_bit(TTY_PUSH, &tty->flags);
1904 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1905 goto do_it_again;
1906
1907 n_tty_set_room(tty);
1908 return retval;
1909}
1910
1911/**
1912 * n_tty_write - write function for tty
1913 * @tty: tty device
1914 * @file: file object
1915 * @buf: userspace buffer pointer
1916 * @nr: size of I/O
1917 *
1918 * Write function of the terminal device. This is serialized with
1919 * respect to other write callers but not to termios changes, reads
1920 * and other such events. Since the receive code will echo characters,
1921 * thus calling driver write methods, the output_lock is used in
1922 * the output processing functions called here as well as in the
1923 * echo processing function to protect the column state and space
1924 * left in the buffer.
1925 *
1926 * This code must be sure never to sleep through a hangup.
1927 *
1928 * Locking: output_lock to protect column state and space left
1929 * (note that the process_output*() functions take this
1930 * lock themselves)
1931 */
1932
1933static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1934 const unsigned char *buf, size_t nr)
1935{
1936 const unsigned char *b = buf;
1937 DECLARE_WAITQUEUE(wait, current);
1938 int c;
1939 ssize_t retval = 0;
1940
1941 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1942 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1943 retval = tty_check_change(tty);
1944 if (retval)
1945 return retval;
1946 }
1947
1948 /* Write out any echoed characters that are still pending */
1949 process_echoes(tty);
1950
1951 add_wait_queue(&tty->write_wait, &wait);
1952 while (1) {
1953 set_current_state(TASK_INTERRUPTIBLE);
1954 if (signal_pending(current)) {
1955 retval = -ERESTARTSYS;
1956 break;
1957 }
1958 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1959 retval = -EIO;
1960 break;
1961 }
1962 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1963 while (nr > 0) {
1964 ssize_t num = process_output_block(tty, b, nr);
1965 if (num < 0) {
1966 if (num == -EAGAIN)
1967 break;
1968 retval = num;
1969 goto break_out;
1970 }
1971 b += num;
1972 nr -= num;
1973 if (nr == 0)
1974 break;
1975 c = *b;
1976 if (process_output(c, tty) < 0)
1977 break;
1978 b++; nr--;
1979 }
1980 if (tty->ops->flush_chars)
1981 tty->ops->flush_chars(tty);
1982 } else {
1983 while (nr > 0) {
1984 c = tty->ops->write(tty, b, nr);
1985 if (c < 0) {
1986 retval = c;
1987 goto break_out;
1988 }
1989 if (!c)
1990 break;
1991 b += c;
1992 nr -= c;
1993 }
1994 }
1995 if (!nr)
1996 break;
1997 if (file->f_flags & O_NONBLOCK) {
1998 retval = -EAGAIN;
1999 break;
2000 }
2001 schedule();
2002 }
2003break_out:
2004 __set_current_state(TASK_RUNNING);
2005 remove_wait_queue(&tty->write_wait, &wait);
2006 if (b - buf != nr && tty->fasync)
2007 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2008 return (b - buf) ? b - buf : retval;
2009}
2010
2011/**
2012 * n_tty_poll - poll method for N_TTY
2013 * @tty: terminal device
2014 * @file: file accessing it
2015 * @wait: poll table
2016 *
2017 * Called when the line discipline is asked to poll() for data or
2018 * for special events. This code is not serialized with respect to
2019 * other events save open/close.
2020 *
2021 * This code must be sure never to sleep through a hangup.
2022 * Called without the kernel lock held - fine
2023 */
2024
2025static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2026 poll_table *wait)
2027{
2028 unsigned int mask = 0;
2029
2030 poll_wait(file, &tty->read_wait, wait);
2031 poll_wait(file, &tty->write_wait, wait);
2032 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2033 mask |= POLLIN | POLLRDNORM;
2034 if (tty->packet && tty->link->ctrl_status)
2035 mask |= POLLPRI | POLLIN | POLLRDNORM;
2036 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2037 mask |= POLLHUP;
2038 if (tty_hung_up_p(file))
2039 mask |= POLLHUP;
2040 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2041 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2042 tty->minimum_to_wake = MIN_CHAR(tty);
2043 else
2044 tty->minimum_to_wake = 1;
2045 }
2046 if (tty->ops->write && !tty_is_writelocked(tty) &&
2047 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2048 tty_write_room(tty) > 0)
2049 mask |= POLLOUT | POLLWRNORM;
2050 return mask;
2051}
2052
2053static unsigned long inq_canon(struct tty_struct *tty)
2054{
2055 int nr, head, tail;
2056
2057 if (!tty->canon_data)
2058 return 0;
2059 head = tty->canon_head;
2060 tail = tty->read_tail;
2061 nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2062 /* Skip EOF-chars.. */
2063 while (head != tail) {
2064 if (test_bit(tail, tty->read_flags) &&
2065 tty->read_buf[tail] == __DISABLED_CHAR)
2066 nr--;
2067 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2068 }
2069 return nr;
2070}
2071
2072static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2073 unsigned int cmd, unsigned long arg)
2074{
2075 int retval;
2076
2077 switch (cmd) {
2078 case TIOCOUTQ:
2079 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2080 case TIOCINQ:
2081 /* FIXME: Locking */
2082 retval = tty->read_cnt;
2083 if (L_ICANON(tty))
2084 retval = inq_canon(tty);
2085 return put_user(retval, (unsigned int __user *) arg);
2086 default:
2087 return n_tty_ioctl_helper(tty, file, cmd, arg);
2088 }
2089}
2090
2091struct tty_ldisc_ops tty_ldisc_N_TTY = {
2092 .magic = TTY_LDISC_MAGIC,
2093 .name = "n_tty",
2094 .open = n_tty_open,
2095 .close = n_tty_close,
2096 .flush_buffer = n_tty_flush_buffer,
2097 .chars_in_buffer = n_tty_chars_in_buffer,
2098 .read = n_tty_read,
2099 .write = n_tty_write,
2100 .ioctl = n_tty_ioctl,
2101 .set_termios = n_tty_set_termios,
2102 .poll = n_tty_poll,
2103 .receive_buf = n_tty_receive_buf,
2104 .write_wakeup = n_tty_write_wakeup
2105};
2106
2107/**
2108 * n_tty_inherit_ops - inherit N_TTY methods
2109 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2110 *
2111 * Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
2112 * methods.
2113 */
2114
2115void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2116{
2117 *ops = tty_ldisc_N_TTY;
2118 ops->owner = NULL;
2119 ops->refcount = ops->flags = 0;
2120}
2121EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-22 20:33:06 -0500