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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/char/n_tty.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'drivers/char/n_tty.c')
-rw-r--r--drivers/char/n_tty.c1562
1 files changed, 1562 insertions, 0 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
new file mode 100644
index 000000000000..edba5a35bf21
--- /dev/null
+++ b/drivers/char/n_tty.c
@@ -0,0 +1,1562 @@
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 write_chan 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
49#include <asm/uaccess.h>
50#include <asm/system.h>
51
52/* number of characters left in xmit buffer before select has we have room */
53#define WAKEUP_CHARS 256
54
55/*
56 * This defines the low- and high-watermarks for throttling and
57 * unthrottling the TTY driver. These watermarks are used for
58 * controlling the space in the read buffer.
59 */
60#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
61#define TTY_THRESHOLD_UNTHROTTLE 128
62
63static inline unsigned char *alloc_buf(void)
64{
65 int prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
66
67 if (PAGE_SIZE != N_TTY_BUF_SIZE)
68 return kmalloc(N_TTY_BUF_SIZE, prio);
69 else
70 return (unsigned char *)__get_free_page(prio);
71}
72
73static inline void free_buf(unsigned char *buf)
74{
75 if (PAGE_SIZE != N_TTY_BUF_SIZE)
76 kfree(buf);
77 else
78 free_page((unsigned long) buf);
79}
80
81static inline void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
82{
83 if (tty->read_cnt < N_TTY_BUF_SIZE) {
84 tty->read_buf[tty->read_head] = c;
85 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
86 tty->read_cnt++;
87 }
88}
89
90static inline void put_tty_queue(unsigned char c, struct tty_struct *tty)
91{
92 unsigned long flags;
93 /*
94 * The problem of stomping on the buffers ends here.
95 * Why didn't anyone see this one coming? --AJK
96 */
97 spin_lock_irqsave(&tty->read_lock, flags);
98 put_tty_queue_nolock(c, tty);
99 spin_unlock_irqrestore(&tty->read_lock, flags);
100}
101
102/**
103 * check_unthrottle - allow new receive data
104 * @tty; tty device
105 *
106 * Check whether to call the driver.unthrottle function.
107 * We test the TTY_THROTTLED bit first so that it always
108 * indicates the current state. The decision about whether
109 * it is worth allowing more input has been taken by the caller.
110 * Can sleep, may be called under the atomic_read semaphore but
111 * this is not guaranteed.
112 */
113
114static void check_unthrottle(struct tty_struct * tty)
115{
116 if (tty->count &&
117 test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
118 tty->driver->unthrottle)
119 tty->driver->unthrottle(tty);
120}
121
122/**
123 * reset_buffer_flags - reset buffer state
124 * @tty: terminal to reset
125 *
126 * Reset the read buffer counters, clear the flags,
127 * and make sure the driver is unthrottled. Called
128 * from n_tty_open() and n_tty_flush_buffer().
129 */
130static void reset_buffer_flags(struct tty_struct *tty)
131{
132 unsigned long flags;
133
134 spin_lock_irqsave(&tty->read_lock, flags);
135 tty->read_head = tty->read_tail = tty->read_cnt = 0;
136 spin_unlock_irqrestore(&tty->read_lock, flags);
137 tty->canon_head = tty->canon_data = tty->erasing = 0;
138 memset(&tty->read_flags, 0, sizeof tty->read_flags);
139 check_unthrottle(tty);
140}
141
142/**
143 * n_tty_flush_buffer - clean input queue
144 * @tty: terminal device
145 *
146 * Flush the input buffer. Called when the line discipline is
147 * being closed, when the tty layer wants the buffer flushed (eg
148 * at hangup) or when the N_TTY line discipline internally has to
149 * clean the pending queue (for example some signals).
150 *
151 * FIXME: tty->ctrl_status is not spinlocked and relies on
152 * lock_kernel() still.
153 */
154
155static void n_tty_flush_buffer(struct tty_struct * tty)
156{
157 /* clear everything and unthrottle the driver */
158 reset_buffer_flags(tty);
159
160 if (!tty->link)
161 return;
162
163 if (tty->link->packet) {
164 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
165 wake_up_interruptible(&tty->link->read_wait);
166 }
167}
168
169/**
170 * n_tty_chars_in_buffer - report available bytes
171 * @tty: tty device
172 *
173 * Report the number of characters buffered to be delivered to user
174 * at this instant in time.
175 */
176
177static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
178{
179 unsigned long flags;
180 ssize_t n = 0;
181
182 spin_lock_irqsave(&tty->read_lock, flags);
183 if (!tty->icanon) {
184 n = tty->read_cnt;
185 } else if (tty->canon_data) {
186 n = (tty->canon_head > tty->read_tail) ?
187 tty->canon_head - tty->read_tail :
188 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
189 }
190 spin_unlock_irqrestore(&tty->read_lock, flags);
191 return n;
192}
193
194/**
195 * is_utf8_continuation - utf8 multibyte check
196 * @c: byte to check
197 *
198 * Returns true if the utf8 character 'c' is a multibyte continuation
199 * character. We use this to correctly compute the on screen size
200 * of the character when printing
201 */
202
203static inline int is_utf8_continuation(unsigned char c)
204{
205 return (c & 0xc0) == 0x80;
206}
207
208/**
209 * is_continuation - multibyte check
210 * @c: byte to check
211 *
212 * Returns true if the utf8 character 'c' is a multibyte continuation
213 * character and the terminal is in unicode mode.
214 */
215
216static inline int is_continuation(unsigned char c, struct tty_struct *tty)
217{
218 return I_IUTF8(tty) && is_utf8_continuation(c);
219}
220
221/**
222 * opost - output post processor
223 * @c: character (or partial unicode symbol)
224 * @tty: terminal device
225 *
226 * Perform OPOST processing. Returns -1 when the output device is
227 * full and the character must be retried. Note that Linux currently
228 * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
229 * relevant in the world today. If you ever need them, add them here.
230 *
231 * Called from both the receive and transmit sides and can be called
232 * re-entrantly. Relies on lock_kernel() still.
233 */
234
235static int opost(unsigned char c, struct tty_struct *tty)
236{
237 int space, spaces;
238
239 space = tty->driver->write_room(tty);
240 if (!space)
241 return -1;
242
243 if (O_OPOST(tty)) {
244 switch (c) {
245 case '\n':
246 if (O_ONLRET(tty))
247 tty->column = 0;
248 if (O_ONLCR(tty)) {
249 if (space < 2)
250 return -1;
251 tty->driver->put_char(tty, '\r');
252 tty->column = 0;
253 }
254 tty->canon_column = tty->column;
255 break;
256 case '\r':
257 if (O_ONOCR(tty) && tty->column == 0)
258 return 0;
259 if (O_OCRNL(tty)) {
260 c = '\n';
261 if (O_ONLRET(tty))
262 tty->canon_column = tty->column = 0;
263 break;
264 }
265 tty->canon_column = tty->column = 0;
266 break;
267 case '\t':
268 spaces = 8 - (tty->column & 7);
269 if (O_TABDLY(tty) == XTABS) {
270 if (space < spaces)
271 return -1;
272 tty->column += spaces;
273 tty->driver->write(tty, " ", spaces);
274 return 0;
275 }
276 tty->column += spaces;
277 break;
278 case '\b':
279 if (tty->column > 0)
280 tty->column--;
281 break;
282 default:
283 if (O_OLCUC(tty))
284 c = toupper(c);
285 if (!iscntrl(c) && !is_continuation(c, tty))
286 tty->column++;
287 break;
288 }
289 }
290 tty->driver->put_char(tty, c);
291 return 0;
292}
293
294/**
295 * opost_block - block postprocess
296 * @tty: terminal device
297 * @inbuf: user buffer
298 * @nr: number of bytes
299 *
300 * This path is used to speed up block console writes, among other
301 * things when processing blocks of output data. It handles only
302 * the simple cases normally found and helps to generate blocks of
303 * symbols for the console driver and thus improve performance.
304 *
305 * Called from write_chan under the tty layer write lock.
306 */
307
308static ssize_t opost_block(struct tty_struct * tty,
309 const unsigned char * buf, unsigned int nr)
310{
311 int space;
312 int i;
313 const unsigned char *cp;
314
315 space = tty->driver->write_room(tty);
316 if (!space)
317 return 0;
318 if (nr > space)
319 nr = space;
320
321 for (i = 0, cp = buf; i < nr; i++, cp++) {
322 switch (*cp) {
323 case '\n':
324 if (O_ONLRET(tty))
325 tty->column = 0;
326 if (O_ONLCR(tty))
327 goto break_out;
328 tty->canon_column = tty->column;
329 break;
330 case '\r':
331 if (O_ONOCR(tty) && tty->column == 0)
332 goto break_out;
333 if (O_OCRNL(tty))
334 goto break_out;
335 tty->canon_column = tty->column = 0;
336 break;
337 case '\t':
338 goto break_out;
339 case '\b':
340 if (tty->column > 0)
341 tty->column--;
342 break;
343 default:
344 if (O_OLCUC(tty))
345 goto break_out;
346 if (!iscntrl(*cp))
347 tty->column++;
348 break;
349 }
350 }
351break_out:
352 if (tty->driver->flush_chars)
353 tty->driver->flush_chars(tty);
354 i = tty->driver->write(tty, buf, i);
355 return i;
356}
357
358
359/**
360 * put_char - write character to driver
361 * @c: character (or part of unicode symbol)
362 * @tty: terminal device
363 *
364 * Queue a byte to the driver layer for output
365 */
366
367static inline void put_char(unsigned char c, struct tty_struct *tty)
368{
369 tty->driver->put_char(tty, c);
370}
371
372/**
373 * echo_char - echo characters
374 * @c: unicode byte to echo
375 * @tty: terminal device
376 *
377 * Echo user input back onto the screen. This must be called only when
378 * L_ECHO(tty) is true. Called from the driver receive_buf path.
379 */
380
381static void echo_char(unsigned char c, struct tty_struct *tty)
382{
383 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
384 put_char('^', tty);
385 put_char(c ^ 0100, tty);
386 tty->column += 2;
387 } else
388 opost(c, tty);
389}
390
391static inline void finish_erasing(struct tty_struct *tty)
392{
393 if (tty->erasing) {
394 put_char('/', tty);
395 tty->column++;
396 tty->erasing = 0;
397 }
398}
399
400/**
401 * eraser - handle erase function
402 * @c: character input
403 * @tty: terminal device
404 *
405 * Perform erase and neccessary output when an erase character is
406 * present in the stream from the driver layer. Handles the complexities
407 * of UTF-8 multibyte symbols.
408 */
409
410static void eraser(unsigned char c, struct tty_struct *tty)
411{
412 enum { ERASE, WERASE, KILL } kill_type;
413 int head, seen_alnums, cnt;
414 unsigned long flags;
415
416 if (tty->read_head == tty->canon_head) {
417 /* opost('\a', tty); */ /* what do you think? */
418 return;
419 }
420 if (c == ERASE_CHAR(tty))
421 kill_type = ERASE;
422 else if (c == WERASE_CHAR(tty))
423 kill_type = WERASE;
424 else {
425 if (!L_ECHO(tty)) {
426 spin_lock_irqsave(&tty->read_lock, flags);
427 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
428 (N_TTY_BUF_SIZE - 1));
429 tty->read_head = tty->canon_head;
430 spin_unlock_irqrestore(&tty->read_lock, flags);
431 return;
432 }
433 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
434 spin_lock_irqsave(&tty->read_lock, flags);
435 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
436 (N_TTY_BUF_SIZE - 1));
437 tty->read_head = tty->canon_head;
438 spin_unlock_irqrestore(&tty->read_lock, flags);
439 finish_erasing(tty);
440 echo_char(KILL_CHAR(tty), tty);
441 /* Add a newline if ECHOK is on and ECHOKE is off. */
442 if (L_ECHOK(tty))
443 opost('\n', tty);
444 return;
445 }
446 kill_type = KILL;
447 }
448
449 seen_alnums = 0;
450 while (tty->read_head != tty->canon_head) {
451 head = tty->read_head;
452
453 /* erase a single possibly multibyte character */
454 do {
455 head = (head - 1) & (N_TTY_BUF_SIZE-1);
456 c = tty->read_buf[head];
457 } while (is_continuation(c, tty) && head != tty->canon_head);
458
459 /* do not partially erase */
460 if (is_continuation(c, tty))
461 break;
462
463 if (kill_type == WERASE) {
464 /* Equivalent to BSD's ALTWERASE. */
465 if (isalnum(c) || c == '_')
466 seen_alnums++;
467 else if (seen_alnums)
468 break;
469 }
470 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
471 spin_lock_irqsave(&tty->read_lock, flags);
472 tty->read_head = head;
473 tty->read_cnt -= cnt;
474 spin_unlock_irqrestore(&tty->read_lock, flags);
475 if (L_ECHO(tty)) {
476 if (L_ECHOPRT(tty)) {
477 if (!tty->erasing) {
478 put_char('\\', tty);
479 tty->column++;
480 tty->erasing = 1;
481 }
482 /* if cnt > 1, output a multi-byte character */
483 echo_char(c, tty);
484 while (--cnt > 0) {
485 head = (head+1) & (N_TTY_BUF_SIZE-1);
486 put_char(tty->read_buf[head], tty);
487 }
488 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
489 echo_char(ERASE_CHAR(tty), tty);
490 } else if (c == '\t') {
491 unsigned int col = tty->canon_column;
492 unsigned long tail = tty->canon_head;
493
494 /* Find the column of the last char. */
495 while (tail != tty->read_head) {
496 c = tty->read_buf[tail];
497 if (c == '\t')
498 col = (col | 7) + 1;
499 else if (iscntrl(c)) {
500 if (L_ECHOCTL(tty))
501 col += 2;
502 } else if (!is_continuation(c, tty))
503 col++;
504 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
505 }
506
507 /* should never happen */
508 if (tty->column > 0x80000000)
509 tty->column = 0;
510
511 /* Now backup to that column. */
512 while (tty->column > col) {
513 /* Can't use opost here. */
514 put_char('\b', tty);
515 if (tty->column > 0)
516 tty->column--;
517 }
518 } else {
519 if (iscntrl(c) && L_ECHOCTL(tty)) {
520 put_char('\b', tty);
521 put_char(' ', tty);
522 put_char('\b', tty);
523 if (tty->column > 0)
524 tty->column--;
525 }
526 if (!iscntrl(c) || L_ECHOCTL(tty)) {
527 put_char('\b', tty);
528 put_char(' ', tty);
529 put_char('\b', tty);
530 if (tty->column > 0)
531 tty->column--;
532 }
533 }
534 }
535 if (kill_type == ERASE)
536 break;
537 }
538 if (tty->read_head == tty->canon_head)
539 finish_erasing(tty);
540}
541
542/**
543 * isig - handle the ISIG optio
544 * @sig: signal
545 * @tty: terminal
546 * @flush: force flush
547 *
548 * Called when a signal is being sent due to terminal input. This
549 * may caus terminal flushing to take place according to the termios
550 * settings and character used. Called from the driver receive_buf
551 * path so serialized.
552 */
553
554static inline void isig(int sig, struct tty_struct *tty, int flush)
555{
556 if (tty->pgrp > 0)
557 kill_pg(tty->pgrp, sig, 1);
558 if (flush || !L_NOFLSH(tty)) {
559 n_tty_flush_buffer(tty);
560 if (tty->driver->flush_buffer)
561 tty->driver->flush_buffer(tty);
562 }
563}
564
565/**
566 * n_tty_receive_break - handle break
567 * @tty: terminal
568 *
569 * An RS232 break event has been hit in the incoming bitstream. This
570 * can cause a variety of events depending upon the termios settings.
571 *
572 * Called from the receive_buf path so single threaded.
573 */
574
575static inline void n_tty_receive_break(struct tty_struct *tty)
576{
577 if (I_IGNBRK(tty))
578 return;
579 if (I_BRKINT(tty)) {
580 isig(SIGINT, tty, 1);
581 return;
582 }
583 if (I_PARMRK(tty)) {
584 put_tty_queue('\377', tty);
585 put_tty_queue('\0', tty);
586 }
587 put_tty_queue('\0', tty);
588 wake_up_interruptible(&tty->read_wait);
589}
590
591/**
592 * n_tty_receive_overrun - handle overrun reporting
593 * @tty: terminal
594 *
595 * Data arrived faster than we could process it. While the tty
596 * driver has flagged this the bits that were missed are gone
597 * forever.
598 *
599 * Called from the receive_buf path so single threaded. Does not
600 * need locking as num_overrun and overrun_time are function
601 * private.
602 */
603
604static inline void n_tty_receive_overrun(struct tty_struct *tty)
605{
606 char buf[64];
607
608 tty->num_overrun++;
609 if (time_before(tty->overrun_time, jiffies - HZ) ||
610 time_after(tty->overrun_time, jiffies)) {
611 printk(KERN_WARNING "%s: %d input overrun(s)\n",
612 tty_name(tty, buf),
613 tty->num_overrun);
614 tty->overrun_time = jiffies;
615 tty->num_overrun = 0;
616 }
617}
618
619/**
620 * n_tty_receive_parity_error - error notifier
621 * @tty: terminal device
622 * @c: character
623 *
624 * Process a parity error and queue the right data to indicate
625 * the error case if neccessary. Locking as per n_tty_receive_buf.
626 */
627static inline void n_tty_receive_parity_error(struct tty_struct *tty,
628 unsigned char c)
629{
630 if (I_IGNPAR(tty)) {
631 return;
632 }
633 if (I_PARMRK(tty)) {
634 put_tty_queue('\377', tty);
635 put_tty_queue('\0', tty);
636 put_tty_queue(c, tty);
637 } else if (I_INPCK(tty))
638 put_tty_queue('\0', tty);
639 else
640 put_tty_queue(c, tty);
641 wake_up_interruptible(&tty->read_wait);
642}
643
644/**
645 * n_tty_receive_char - perform processing
646 * @tty: terminal device
647 * @c: character
648 *
649 * Process an individual character of input received from the driver.
650 * This is serialized with respect to itself by the rules for the
651 * driver above.
652 */
653
654static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
655{
656 unsigned long flags;
657
658 if (tty->raw) {
659 put_tty_queue(c, tty);
660 return;
661 }
662
663 if (tty->stopped && !tty->flow_stopped &&
664 I_IXON(tty) && I_IXANY(tty)) {
665 start_tty(tty);
666 return;
667 }
668
669 if (I_ISTRIP(tty))
670 c &= 0x7f;
671 if (I_IUCLC(tty) && L_IEXTEN(tty))
672 c=tolower(c);
673
674 if (tty->closing) {
675 if (I_IXON(tty)) {
676 if (c == START_CHAR(tty))
677 start_tty(tty);
678 else if (c == STOP_CHAR(tty))
679 stop_tty(tty);
680 }
681 return;
682 }
683
684 /*
685 * If the previous character was LNEXT, or we know that this
686 * character is not one of the characters that we'll have to
687 * handle specially, do shortcut processing to speed things
688 * up.
689 */
690 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
691 finish_erasing(tty);
692 tty->lnext = 0;
693 if (L_ECHO(tty)) {
694 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
695 put_char('\a', tty); /* beep if no space */
696 return;
697 }
698 /* Record the column of first canon char. */
699 if (tty->canon_head == tty->read_head)
700 tty->canon_column = tty->column;
701 echo_char(c, tty);
702 }
703 if (I_PARMRK(tty) && c == (unsigned char) '\377')
704 put_tty_queue(c, tty);
705 put_tty_queue(c, tty);
706 return;
707 }
708
709 if (c == '\r') {
710 if (I_IGNCR(tty))
711 return;
712 if (I_ICRNL(tty))
713 c = '\n';
714 } else if (c == '\n' && I_INLCR(tty))
715 c = '\r';
716 if (I_IXON(tty)) {
717 if (c == START_CHAR(tty)) {
718 start_tty(tty);
719 return;
720 }
721 if (c == STOP_CHAR(tty)) {
722 stop_tty(tty);
723 return;
724 }
725 }
726 if (L_ISIG(tty)) {
727 int signal;
728 signal = SIGINT;
729 if (c == INTR_CHAR(tty))
730 goto send_signal;
731 signal = SIGQUIT;
732 if (c == QUIT_CHAR(tty))
733 goto send_signal;
734 signal = SIGTSTP;
735 if (c == SUSP_CHAR(tty)) {
736send_signal:
737 isig(signal, tty, 0);
738 return;
739 }
740 }
741 if (tty->icanon) {
742 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
743 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
744 eraser(c, tty);
745 return;
746 }
747 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
748 tty->lnext = 1;
749 if (L_ECHO(tty)) {
750 finish_erasing(tty);
751 if (L_ECHOCTL(tty)) {
752 put_char('^', tty);
753 put_char('\b', tty);
754 }
755 }
756 return;
757 }
758 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
759 L_IEXTEN(tty)) {
760 unsigned long tail = tty->canon_head;
761
762 finish_erasing(tty);
763 echo_char(c, tty);
764 opost('\n', tty);
765 while (tail != tty->read_head) {
766 echo_char(tty->read_buf[tail], tty);
767 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
768 }
769 return;
770 }
771 if (c == '\n') {
772 if (L_ECHO(tty) || L_ECHONL(tty)) {
773 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
774 put_char('\a', tty);
775 return;
776 }
777 opost('\n', tty);
778 }
779 goto handle_newline;
780 }
781 if (c == EOF_CHAR(tty)) {
782 if (tty->canon_head != tty->read_head)
783 set_bit(TTY_PUSH, &tty->flags);
784 c = __DISABLED_CHAR;
785 goto handle_newline;
786 }
787 if ((c == EOL_CHAR(tty)) ||
788 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
789 /*
790 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
791 */
792 if (L_ECHO(tty)) {
793 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
794 put_char('\a', tty);
795 return;
796 }
797 /* Record the column of first canon char. */
798 if (tty->canon_head == tty->read_head)
799 tty->canon_column = tty->column;
800 echo_char(c, tty);
801 }
802 /*
803 * XXX does PARMRK doubling happen for
804 * EOL_CHAR and EOL2_CHAR?
805 */
806 if (I_PARMRK(tty) && c == (unsigned char) '\377')
807 put_tty_queue(c, tty);
808
809 handle_newline:
810 spin_lock_irqsave(&tty->read_lock, flags);
811 set_bit(tty->read_head, tty->read_flags);
812 put_tty_queue_nolock(c, tty);
813 tty->canon_head = tty->read_head;
814 tty->canon_data++;
815 spin_unlock_irqrestore(&tty->read_lock, flags);
816 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
817 if (waitqueue_active(&tty->read_wait))
818 wake_up_interruptible(&tty->read_wait);
819 return;
820 }
821 }
822
823 finish_erasing(tty);
824 if (L_ECHO(tty)) {
825 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
826 put_char('\a', tty); /* beep if no space */
827 return;
828 }
829 if (c == '\n')
830 opost('\n', tty);
831 else {
832 /* Record the column of first canon char. */
833 if (tty->canon_head == tty->read_head)
834 tty->canon_column = tty->column;
835 echo_char(c, tty);
836 }
837 }
838
839 if (I_PARMRK(tty) && c == (unsigned char) '\377')
840 put_tty_queue(c, tty);
841
842 put_tty_queue(c, tty);
843}
844
845/**
846 * n_tty_receive_room - receive space
847 * @tty: terminal
848 *
849 * Called by the driver to find out how much data it is
850 * permitted to feed to the line discipline without any being lost
851 * and thus to manage flow control. Not serialized. Answers for the
852 * "instant".
853 */
854
855static int n_tty_receive_room(struct tty_struct *tty)
856{
857 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
858
859 /*
860 * If we are doing input canonicalization, and there are no
861 * pending newlines, let characters through without limit, so
862 * that erase characters will be handled. Other excess
863 * characters will be beeped.
864 */
865 if (tty->icanon && !tty->canon_data)
866 return N_TTY_BUF_SIZE;
867
868 if (left > 0)
869 return left;
870 return 0;
871}
872
873/**
874 * n_tty_write_wakeup - asynchronous I/O notifier
875 * @tty: tty device
876 *
877 * Required for the ptys, serial driver etc. since processes
878 * that attach themselves to the master and rely on ASYNC
879 * IO must be woken up
880 */
881
882static void n_tty_write_wakeup(struct tty_struct *tty)
883{
884 if (tty->fasync)
885 {
886 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
887 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
888 }
889 return;
890}
891
892/**
893 * n_tty_receive_buf - data receive
894 * @tty: terminal device
895 * @cp: buffer
896 * @fp: flag buffer
897 * @count: characters
898 *
899 * Called by the terminal driver when a block of characters has
900 * been received. This function must be called from soft contexts
901 * not from interrupt context. The driver is responsible for making
902 * calls one at a time and in order (or using flush_to_ldisc)
903 */
904
905static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
906 char *fp, int count)
907{
908 const unsigned char *p;
909 char *f, flags = TTY_NORMAL;
910 int i;
911 char buf[64];
912 unsigned long cpuflags;
913
914 if (!tty->read_buf)
915 return;
916
917 if (tty->real_raw) {
918 spin_lock_irqsave(&tty->read_lock, cpuflags);
919 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
920 N_TTY_BUF_SIZE - tty->read_head);
921 i = min(count, i);
922 memcpy(tty->read_buf + tty->read_head, cp, i);
923 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
924 tty->read_cnt += i;
925 cp += i;
926 count -= i;
927
928 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
929 N_TTY_BUF_SIZE - tty->read_head);
930 i = min(count, i);
931 memcpy(tty->read_buf + tty->read_head, cp, i);
932 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
933 tty->read_cnt += i;
934 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
935 } else {
936 for (i=count, p = cp, f = fp; i; i--, p++) {
937 if (f)
938 flags = *f++;
939 switch (flags) {
940 case TTY_NORMAL:
941 n_tty_receive_char(tty, *p);
942 break;
943 case TTY_BREAK:
944 n_tty_receive_break(tty);
945 break;
946 case TTY_PARITY:
947 case TTY_FRAME:
948 n_tty_receive_parity_error(tty, *p);
949 break;
950 case TTY_OVERRUN:
951 n_tty_receive_overrun(tty);
952 break;
953 default:
954 printk("%s: unknown flag %d\n",
955 tty_name(tty, buf), flags);
956 break;
957 }
958 }
959 if (tty->driver->flush_chars)
960 tty->driver->flush_chars(tty);
961 }
962
963 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
964 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
965 if (waitqueue_active(&tty->read_wait))
966 wake_up_interruptible(&tty->read_wait);
967 }
968
969 /*
970 * Check the remaining room for the input canonicalization
971 * mode. We don't want to throttle the driver if we're in
972 * canonical mode and don't have a newline yet!
973 */
974 if (n_tty_receive_room(tty) < TTY_THRESHOLD_THROTTLE) {
975 /* check TTY_THROTTLED first so it indicates our state */
976 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
977 tty->driver->throttle)
978 tty->driver->throttle(tty);
979 }
980}
981
982int is_ignored(int sig)
983{
984 return (sigismember(&current->blocked, sig) ||
985 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
986}
987
988/**
989 * n_tty_set_termios - termios data changed
990 * @tty: terminal
991 * @old: previous data
992 *
993 * Called by the tty layer when the user changes termios flags so
994 * that the line discipline can plan ahead. This function cannot sleep
995 * and is protected from re-entry by the tty layer. The user is
996 * guaranteed that this function will not be re-entered or in progress
997 * when the ldisc is closed.
998 */
999
1000static void n_tty_set_termios(struct tty_struct *tty, struct termios * old)
1001{
1002 if (!tty)
1003 return;
1004
1005 tty->icanon = (L_ICANON(tty) != 0);
1006 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1007 tty->raw = 1;
1008 tty->real_raw = 1;
1009 return;
1010 }
1011 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1012 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1013 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1014 I_PARMRK(tty)) {
1015 memset(tty->process_char_map, 0, 256/8);
1016
1017 if (I_IGNCR(tty) || I_ICRNL(tty))
1018 set_bit('\r', tty->process_char_map);
1019 if (I_INLCR(tty))
1020 set_bit('\n', tty->process_char_map);
1021
1022 if (L_ICANON(tty)) {
1023 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1024 set_bit(KILL_CHAR(tty), tty->process_char_map);
1025 set_bit(EOF_CHAR(tty), tty->process_char_map);
1026 set_bit('\n', tty->process_char_map);
1027 set_bit(EOL_CHAR(tty), tty->process_char_map);
1028 if (L_IEXTEN(tty)) {
1029 set_bit(WERASE_CHAR(tty),
1030 tty->process_char_map);
1031 set_bit(LNEXT_CHAR(tty),
1032 tty->process_char_map);
1033 set_bit(EOL2_CHAR(tty),
1034 tty->process_char_map);
1035 if (L_ECHO(tty))
1036 set_bit(REPRINT_CHAR(tty),
1037 tty->process_char_map);
1038 }
1039 }
1040 if (I_IXON(tty)) {
1041 set_bit(START_CHAR(tty), tty->process_char_map);
1042 set_bit(STOP_CHAR(tty), tty->process_char_map);
1043 }
1044 if (L_ISIG(tty)) {
1045 set_bit(INTR_CHAR(tty), tty->process_char_map);
1046 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1047 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1048 }
1049 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1050 tty->raw = 0;
1051 tty->real_raw = 0;
1052 } else {
1053 tty->raw = 1;
1054 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1055 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1056 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1057 tty->real_raw = 1;
1058 else
1059 tty->real_raw = 0;
1060 }
1061}
1062
1063/**
1064 * n_tty_close - close the ldisc for this tty
1065 * @tty: device
1066 *
1067 * Called from the terminal layer when this line discipline is
1068 * being shut down, either because of a close or becsuse of a
1069 * discipline change. The function will not be called while other
1070 * ldisc methods are in progress.
1071 */
1072
1073static void n_tty_close(struct tty_struct *tty)
1074{
1075 n_tty_flush_buffer(tty);
1076 if (tty->read_buf) {
1077 free_buf(tty->read_buf);
1078 tty->read_buf = NULL;
1079 }
1080}
1081
1082/**
1083 * n_tty_open - open an ldisc
1084 * @tty: terminal to open
1085 *
1086 * Called when this line discipline is being attached to the
1087 * terminal device. Can sleep. Called serialized so that no
1088 * other events will occur in parallel. No further open will occur
1089 * until a close.
1090 */
1091
1092static int n_tty_open(struct tty_struct *tty)
1093{
1094 if (!tty)
1095 return -EINVAL;
1096
1097 /* This one is ugly. Currently a malloc failure here can panic */
1098 if (!tty->read_buf) {
1099 tty->read_buf = alloc_buf();
1100 if (!tty->read_buf)
1101 return -ENOMEM;
1102 }
1103 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1104 reset_buffer_flags(tty);
1105 tty->column = 0;
1106 n_tty_set_termios(tty, NULL);
1107 tty->minimum_to_wake = 1;
1108 tty->closing = 0;
1109 return 0;
1110}
1111
1112static inline int input_available_p(struct tty_struct *tty, int amt)
1113{
1114 if (tty->icanon) {
1115 if (tty->canon_data)
1116 return 1;
1117 } else if (tty->read_cnt >= (amt ? amt : 1))
1118 return 1;
1119
1120 return 0;
1121}
1122
1123/**
1124 * copy_from_read_buf - copy read data directly
1125 * @tty: terminal device
1126 * @b: user data
1127 * @nr: size of data
1128 *
1129 * Helper function to speed up read_chan. It is only called when
1130 * ICANON is off; it copies characters straight from the tty queue to
1131 * user space directly. It can be profitably called twice; once to
1132 * drain the space from the tail pointer to the (physical) end of the
1133 * buffer, and once to drain the space from the (physical) beginning of
1134 * the buffer to head pointer.
1135 *
1136 * Called under the tty->atomic_read sem and with TTY_DONT_FLIP set
1137 *
1138 */
1139
1140static inline int copy_from_read_buf(struct tty_struct *tty,
1141 unsigned char __user **b,
1142 size_t *nr)
1143
1144{
1145 int retval;
1146 size_t n;
1147 unsigned long flags;
1148
1149 retval = 0;
1150 spin_lock_irqsave(&tty->read_lock, flags);
1151 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1152 n = min(*nr, n);
1153 spin_unlock_irqrestore(&tty->read_lock, flags);
1154 if (n) {
1155 mb();
1156 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1157 n -= retval;
1158 spin_lock_irqsave(&tty->read_lock, flags);
1159 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1160 tty->read_cnt -= n;
1161 spin_unlock_irqrestore(&tty->read_lock, flags);
1162 *b += n;
1163 *nr -= n;
1164 }
1165 return retval;
1166}
1167
1168extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *);
1169
1170/**
1171 * job_control - check job control
1172 * @tty: tty
1173 * @file: file handle
1174 *
1175 * Perform job control management checks on this file/tty descriptor
1176 * and if appropriate send any needed signals and return a negative
1177 * error code if action should be taken.
1178 */
1179
1180static int job_control(struct tty_struct *tty, struct file *file)
1181{
1182 /* Job control check -- must be done at start and after
1183 every sleep (POSIX.1 7.1.1.4). */
1184 /* NOTE: not yet done after every sleep pending a thorough
1185 check of the logic of this change. -- jlc */
1186 /* don't stop on /dev/console */
1187 if (file->f_op->write != redirected_tty_write &&
1188 current->signal->tty == tty) {
1189 if (tty->pgrp <= 0)
1190 printk("read_chan: tty->pgrp <= 0!\n");
1191 else if (process_group(current) != tty->pgrp) {
1192 if (is_ignored(SIGTTIN) ||
1193 is_orphaned_pgrp(process_group(current)))
1194 return -EIO;
1195 kill_pg(process_group(current), SIGTTIN, 1);
1196 return -ERESTARTSYS;
1197 }
1198 }
1199 return 0;
1200}
1201
1202
1203/**
1204 * read_chan - read function for tty
1205 * @tty: tty device
1206 * @file: file object
1207 * @buf: userspace buffer pointer
1208 * @nr: size of I/O
1209 *
1210 * Perform reads for the line discipline. We are guaranteed that the
1211 * line discipline will not be closed under us but we may get multiple
1212 * parallel readers and must handle this ourselves. We may also get
1213 * a hangup. Always called in user context, may sleep.
1214 *
1215 * This code must be sure never to sleep through a hangup.
1216 */
1217
1218static ssize_t read_chan(struct tty_struct *tty, struct file *file,
1219 unsigned char __user *buf, size_t nr)
1220{
1221 unsigned char __user *b = buf;
1222 DECLARE_WAITQUEUE(wait, current);
1223 int c;
1224 int minimum, time;
1225 ssize_t retval = 0;
1226 ssize_t size;
1227 long timeout;
1228 unsigned long flags;
1229
1230do_it_again:
1231
1232 if (!tty->read_buf) {
1233 printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
1234 return -EIO;
1235 }
1236
1237 c = job_control(tty, file);
1238 if(c < 0)
1239 return c;
1240
1241 minimum = time = 0;
1242 timeout = MAX_SCHEDULE_TIMEOUT;
1243 if (!tty->icanon) {
1244 time = (HZ / 10) * TIME_CHAR(tty);
1245 minimum = MIN_CHAR(tty);
1246 if (minimum) {
1247 if (time)
1248 tty->minimum_to_wake = 1;
1249 else if (!waitqueue_active(&tty->read_wait) ||
1250 (tty->minimum_to_wake > minimum))
1251 tty->minimum_to_wake = minimum;
1252 } else {
1253 timeout = 0;
1254 if (time) {
1255 timeout = time;
1256 time = 0;
1257 }
1258 tty->minimum_to_wake = minimum = 1;
1259 }
1260 }
1261
1262 /*
1263 * Internal serialization of reads.
1264 */
1265 if (file->f_flags & O_NONBLOCK) {
1266 if (down_trylock(&tty->atomic_read))
1267 return -EAGAIN;
1268 }
1269 else {
1270 if (down_interruptible(&tty->atomic_read))
1271 return -ERESTARTSYS;
1272 }
1273
1274 add_wait_queue(&tty->read_wait, &wait);
1275 set_bit(TTY_DONT_FLIP, &tty->flags);
1276 while (nr) {
1277 /* First test for status change. */
1278 if (tty->packet && tty->link->ctrl_status) {
1279 unsigned char cs;
1280 if (b != buf)
1281 break;
1282 cs = tty->link->ctrl_status;
1283 tty->link->ctrl_status = 0;
1284 if (put_user(cs, b++)) {
1285 retval = -EFAULT;
1286 b--;
1287 break;
1288 }
1289 nr--;
1290 break;
1291 }
1292 /* This statement must be first before checking for input
1293 so that any interrupt will set the state back to
1294 TASK_RUNNING. */
1295 set_current_state(TASK_INTERRUPTIBLE);
1296
1297 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1298 ((minimum - (b - buf)) >= 1))
1299 tty->minimum_to_wake = (minimum - (b - buf));
1300
1301 if (!input_available_p(tty, 0)) {
1302 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1303 retval = -EIO;
1304 break;
1305 }
1306 if (tty_hung_up_p(file))
1307 break;
1308 if (!timeout)
1309 break;
1310 if (file->f_flags & O_NONBLOCK) {
1311 retval = -EAGAIN;
1312 break;
1313 }
1314 if (signal_pending(current)) {
1315 retval = -ERESTARTSYS;
1316 break;
1317 }
1318 clear_bit(TTY_DONT_FLIP, &tty->flags);
1319 timeout = schedule_timeout(timeout);
1320 set_bit(TTY_DONT_FLIP, &tty->flags);
1321 continue;
1322 }
1323 __set_current_state(TASK_RUNNING);
1324
1325 /* Deal with packet mode. */
1326 if (tty->packet && b == buf) {
1327 if (put_user(TIOCPKT_DATA, b++)) {
1328 retval = -EFAULT;
1329 b--;
1330 break;
1331 }
1332 nr--;
1333 }
1334
1335 if (tty->icanon) {
1336 /* N.B. avoid overrun if nr == 0 */
1337 while (nr && tty->read_cnt) {
1338 int eol;
1339
1340 eol = test_and_clear_bit(tty->read_tail,
1341 tty->read_flags);
1342 c = tty->read_buf[tty->read_tail];
1343 spin_lock_irqsave(&tty->read_lock, flags);
1344 tty->read_tail = ((tty->read_tail+1) &
1345 (N_TTY_BUF_SIZE-1));
1346 tty->read_cnt--;
1347 if (eol) {
1348 /* this test should be redundant:
1349 * we shouldn't be reading data if
1350 * canon_data is 0
1351 */
1352 if (--tty->canon_data < 0)
1353 tty->canon_data = 0;
1354 }
1355 spin_unlock_irqrestore(&tty->read_lock, flags);
1356
1357 if (!eol || (c != __DISABLED_CHAR)) {
1358 if (put_user(c, b++)) {
1359 retval = -EFAULT;
1360 b--;
1361 break;
1362 }
1363 nr--;
1364 }
1365 if (eol)
1366 break;
1367 }
1368 if (retval)
1369 break;
1370 } else {
1371 int uncopied;
1372 uncopied = copy_from_read_buf(tty, &b, &nr);
1373 uncopied += copy_from_read_buf(tty, &b, &nr);
1374 if (uncopied) {
1375 retval = -EFAULT;
1376 break;
1377 }
1378 }
1379
1380 /* If there is enough space in the read buffer now, let the
1381 * low-level driver know. We use n_tty_chars_in_buffer() to
1382 * check the buffer, as it now knows about canonical mode.
1383 * Otherwise, if the driver is throttled and the line is
1384 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1385 * we won't get any more characters.
1386 */
1387 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE)
1388 check_unthrottle(tty);
1389
1390 if (b - buf >= minimum)
1391 break;
1392 if (time)
1393 timeout = time;
1394 }
1395 clear_bit(TTY_DONT_FLIP, &tty->flags);
1396 up(&tty->atomic_read);
1397 remove_wait_queue(&tty->read_wait, &wait);
1398
1399 if (!waitqueue_active(&tty->read_wait))
1400 tty->minimum_to_wake = minimum;
1401
1402 __set_current_state(TASK_RUNNING);
1403 size = b - buf;
1404 if (size) {
1405 retval = size;
1406 if (nr)
1407 clear_bit(TTY_PUSH, &tty->flags);
1408 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1409 goto do_it_again;
1410
1411 return retval;
1412}
1413
1414/**
1415 * write_chan - write function for tty
1416 * @tty: tty device
1417 * @file: file object
1418 * @buf: userspace buffer pointer
1419 * @nr: size of I/O
1420 *
1421 * Write function of the terminal device. This is serialized with
1422 * respect to other write callers but not to termios changes, reads
1423 * and other such events. We must be careful with N_TTY as the receive
1424 * code will echo characters, thus calling driver write methods.
1425 *
1426 * This code must be sure never to sleep through a hangup.
1427 */
1428
1429static ssize_t write_chan(struct tty_struct * tty, struct file * file,
1430 const unsigned char * buf, size_t nr)
1431{
1432 const unsigned char *b = buf;
1433 DECLARE_WAITQUEUE(wait, current);
1434 int c;
1435 ssize_t retval = 0;
1436
1437 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1438 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1439 retval = tty_check_change(tty);
1440 if (retval)
1441 return retval;
1442 }
1443
1444 add_wait_queue(&tty->write_wait, &wait);
1445 while (1) {
1446 set_current_state(TASK_INTERRUPTIBLE);
1447 if (signal_pending(current)) {
1448 retval = -ERESTARTSYS;
1449 break;
1450 }
1451 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1452 retval = -EIO;
1453 break;
1454 }
1455 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1456 while (nr > 0) {
1457 ssize_t num = opost_block(tty, b, nr);
1458 if (num < 0) {
1459 if (num == -EAGAIN)
1460 break;
1461 retval = num;
1462 goto break_out;
1463 }
1464 b += num;
1465 nr -= num;
1466 if (nr == 0)
1467 break;
1468 c = *b;
1469 if (opost(c, tty) < 0)
1470 break;
1471 b++; nr--;
1472 }
1473 if (tty->driver->flush_chars)
1474 tty->driver->flush_chars(tty);
1475 } else {
1476 c = tty->driver->write(tty, b, nr);
1477 if (c < 0) {
1478 retval = c;
1479 goto break_out;
1480 }
1481 b += c;
1482 nr -= c;
1483 }
1484 if (!nr)
1485 break;
1486 if (file->f_flags & O_NONBLOCK) {
1487 retval = -EAGAIN;
1488 break;
1489 }
1490 schedule();
1491 }
1492break_out:
1493 __set_current_state(TASK_RUNNING);
1494 remove_wait_queue(&tty->write_wait, &wait);
1495 return (b - buf) ? b - buf : retval;
1496}
1497
1498/**
1499 * normal_poll - poll method for N_TTY
1500 * @tty: terminal device
1501 * @file: file accessing it
1502 * @wait: poll table
1503 *
1504 * Called when the line discipline is asked to poll() for data or
1505 * for special events. This code is not serialized with respect to
1506 * other events save open/close.
1507 *
1508 * This code must be sure never to sleep through a hangup.
1509 * Called without the kernel lock held - fine
1510 *
1511 * FIXME: if someone changes the VMIN or discipline settings for the
1512 * terminal while another process is in poll() the poll does not
1513 * recompute the new limits. Possibly set_termios should issue
1514 * a read wakeup to fix this bug.
1515 */
1516
1517static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait)
1518{
1519 unsigned int mask = 0;
1520
1521 poll_wait(file, &tty->read_wait, wait);
1522 poll_wait(file, &tty->write_wait, wait);
1523 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1524 mask |= POLLIN | POLLRDNORM;
1525 if (tty->packet && tty->link->ctrl_status)
1526 mask |= POLLPRI | POLLIN | POLLRDNORM;
1527 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1528 mask |= POLLHUP;
1529 if (tty_hung_up_p(file))
1530 mask |= POLLHUP;
1531 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1532 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1533 tty->minimum_to_wake = MIN_CHAR(tty);
1534 else
1535 tty->minimum_to_wake = 1;
1536 }
1537 if (tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
1538 tty->driver->write_room(tty) > 0)
1539 mask |= POLLOUT | POLLWRNORM;
1540 return mask;
1541}
1542
1543struct tty_ldisc tty_ldisc_N_TTY = {
1544 TTY_LDISC_MAGIC, /* magic */
1545 "n_tty", /* name */
1546 0, /* num */
1547 0, /* flags */
1548 n_tty_open, /* open */
1549 n_tty_close, /* close */
1550 n_tty_flush_buffer, /* flush_buffer */
1551 n_tty_chars_in_buffer, /* chars_in_buffer */
1552 read_chan, /* read */
1553 write_chan, /* write */
1554 n_tty_ioctl, /* ioctl */
1555 n_tty_set_termios, /* set_termios */
1556 normal_poll, /* poll */
1557 NULL, /* hangup */
1558 n_tty_receive_buf, /* receive_buf */
1559 n_tty_receive_room, /* receive_room */
1560 n_tty_write_wakeup /* write_wakeup */
1561};
1562
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-08 03:54:51 -0500