pcmcia: CompactFlash driver for PA Semi Electra boards
[pv_ops_mirror.git] / drivers / char / n_tty.c
blob038056911934c3b60a10a70553702ff33cb070b6
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...)
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.
13 * Written by Theodore Ts'o, Copyright 1994.
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18 * This file may be redistributed under the terms of the GNU General Public
19 * License.
21 * Reduced memory usage for older ARM systems - Russell King.
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.
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
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>
51 #include <asm/uaccess.h>
52 #include <asm/system.h>
54 /* number of characters left in xmit buffer before select has we have room */
55 #define WAKEUP_CHARS 256
58 * This defines the low- and high-watermarks for throttling and
59 * unthrottling the TTY driver. These watermarks are used for
60 * controlling the space in the read buffer.
62 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
63 #define TTY_THRESHOLD_UNTHROTTLE 128
65 static inline unsigned char *alloc_buf(void)
67 gfp_t prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
69 if (PAGE_SIZE != N_TTY_BUF_SIZE)
70 return kmalloc(N_TTY_BUF_SIZE, prio);
71 else
72 return (unsigned char *)__get_free_page(prio);
75 static inline void free_buf(unsigned char *buf)
77 if (PAGE_SIZE != N_TTY_BUF_SIZE)
78 kfree(buf);
79 else
80 free_page((unsigned long) buf);
83 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
84 unsigned char __user *ptr)
86 tty_audit_add_data(tty, &x, 1);
87 return put_user(x, ptr);
90 /**
91 * n_tty_set__room - receive space
92 * @tty: terminal
94 * Called by the driver to find out how much data it is
95 * permitted to feed to the line discipline without any being lost
96 * and thus to manage flow control. Not serialized. Answers for the
97 * "instant".
100 static void n_tty_set_room(struct tty_struct *tty)
102 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
105 * If we are doing input canonicalization, and there are no
106 * pending newlines, let characters through without limit, so
107 * that erase characters will be handled. Other excess
108 * characters will be beeped.
110 if (left <= 0)
111 left = tty->icanon && !tty->canon_data;
112 tty->receive_room = left;
115 static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
117 if (tty->read_cnt < N_TTY_BUF_SIZE) {
118 tty->read_buf[tty->read_head] = c;
119 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
120 tty->read_cnt++;
124 static void put_tty_queue(unsigned char c, struct tty_struct *tty)
126 unsigned long flags;
128 * The problem of stomping on the buffers ends here.
129 * Why didn't anyone see this one coming? --AJK
131 spin_lock_irqsave(&tty->read_lock, flags);
132 put_tty_queue_nolock(c, tty);
133 spin_unlock_irqrestore(&tty->read_lock, flags);
137 * check_unthrottle - allow new receive data
138 * @tty; tty device
140 * Check whether to call the driver.unthrottle function.
141 * We test the TTY_THROTTLED bit first so that it always
142 * indicates the current state. The decision about whether
143 * it is worth allowing more input has been taken by the caller.
144 * Can sleep, may be called under the atomic_read_lock mutex but
145 * this is not guaranteed.
148 static void check_unthrottle(struct tty_struct * tty)
150 if (tty->count &&
151 test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
152 tty->driver->unthrottle)
153 tty->driver->unthrottle(tty);
157 * reset_buffer_flags - reset buffer state
158 * @tty: terminal to reset
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().
164 static void reset_buffer_flags(struct tty_struct *tty)
166 unsigned long flags;
168 spin_lock_irqsave(&tty->read_lock, flags);
169 tty->read_head = tty->read_tail = tty->read_cnt = 0;
170 spin_unlock_irqrestore(&tty->read_lock, flags);
171 tty->canon_head = tty->canon_data = tty->erasing = 0;
172 memset(&tty->read_flags, 0, sizeof tty->read_flags);
173 n_tty_set_room(tty);
174 check_unthrottle(tty);
178 * n_tty_flush_buffer - clean input queue
179 * @tty: terminal device
181 * Flush the input buffer. Called when the line discipline is
182 * being closed, when the tty layer wants the buffer flushed (eg
183 * at hangup) or when the N_TTY line discipline internally has to
184 * clean the pending queue (for example some signals).
186 * FIXME: tty->ctrl_status is not spinlocked and relies on
187 * lock_kernel() still.
190 static void n_tty_flush_buffer(struct tty_struct * tty)
192 /* clear everything and unthrottle the driver */
193 reset_buffer_flags(tty);
195 if (!tty->link)
196 return;
198 if (tty->link->packet) {
199 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
200 wake_up_interruptible(&tty->link->read_wait);
205 * n_tty_chars_in_buffer - report available bytes
206 * @tty: tty device
208 * Report the number of characters buffered to be delivered to user
209 * at this instant in time.
212 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
214 unsigned long flags;
215 ssize_t n = 0;
217 spin_lock_irqsave(&tty->read_lock, flags);
218 if (!tty->icanon) {
219 n = tty->read_cnt;
220 } else if (tty->canon_data) {
221 n = (tty->canon_head > tty->read_tail) ?
222 tty->canon_head - tty->read_tail :
223 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
225 spin_unlock_irqrestore(&tty->read_lock, flags);
226 return n;
230 * is_utf8_continuation - utf8 multibyte check
231 * @c: byte to check
233 * Returns true if the utf8 character 'c' is a multibyte continuation
234 * character. We use this to correctly compute the on screen size
235 * of the character when printing
238 static inline int is_utf8_continuation(unsigned char c)
240 return (c & 0xc0) == 0x80;
244 * is_continuation - multibyte check
245 * @c: byte to check
247 * Returns true if the utf8 character 'c' is a multibyte continuation
248 * character and the terminal is in unicode mode.
251 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
253 return I_IUTF8(tty) && is_utf8_continuation(c);
257 * opost - output post processor
258 * @c: character (or partial unicode symbol)
259 * @tty: terminal device
261 * Perform OPOST processing. Returns -1 when the output device is
262 * full and the character must be retried. Note that Linux currently
263 * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
264 * relevant in the world today. If you ever need them, add them here.
266 * Called from both the receive and transmit sides and can be called
267 * re-entrantly. Relies on lock_kernel() still.
270 static int opost(unsigned char c, struct tty_struct *tty)
272 int space, spaces;
274 space = tty->driver->write_room(tty);
275 if (!space)
276 return -1;
278 if (O_OPOST(tty)) {
279 switch (c) {
280 case '\n':
281 if (O_ONLRET(tty))
282 tty->column = 0;
283 if (O_ONLCR(tty)) {
284 if (space < 2)
285 return -1;
286 tty->driver->put_char(tty, '\r');
287 tty->column = 0;
289 tty->canon_column = tty->column;
290 break;
291 case '\r':
292 if (O_ONOCR(tty) && tty->column == 0)
293 return 0;
294 if (O_OCRNL(tty)) {
295 c = '\n';
296 if (O_ONLRET(tty))
297 tty->canon_column = tty->column = 0;
298 break;
300 tty->canon_column = tty->column = 0;
301 break;
302 case '\t':
303 spaces = 8 - (tty->column & 7);
304 if (O_TABDLY(tty) == XTABS) {
305 if (space < spaces)
306 return -1;
307 tty->column += spaces;
308 tty->driver->write(tty, " ", spaces);
309 return 0;
311 tty->column += spaces;
312 break;
313 case '\b':
314 if (tty->column > 0)
315 tty->column--;
316 break;
317 default:
318 if (O_OLCUC(tty))
319 c = toupper(c);
320 if (!iscntrl(c) && !is_continuation(c, tty))
321 tty->column++;
322 break;
325 tty->driver->put_char(tty, c);
326 return 0;
330 * opost_block - block postprocess
331 * @tty: terminal device
332 * @inbuf: user buffer
333 * @nr: number of bytes
335 * This path is used to speed up block console writes, among other
336 * things when processing blocks of output data. It handles only
337 * the simple cases normally found and helps to generate blocks of
338 * symbols for the console driver and thus improve performance.
340 * Called from write_chan under the tty layer write lock.
343 static ssize_t opost_block(struct tty_struct * tty,
344 const unsigned char * buf, unsigned int nr)
346 int space;
347 int i;
348 const unsigned char *cp;
350 space = tty->driver->write_room(tty);
351 if (!space)
352 return 0;
353 if (nr > space)
354 nr = space;
356 for (i = 0, cp = buf; i < nr; i++, cp++) {
357 switch (*cp) {
358 case '\n':
359 if (O_ONLRET(tty))
360 tty->column = 0;
361 if (O_ONLCR(tty))
362 goto break_out;
363 tty->canon_column = tty->column;
364 break;
365 case '\r':
366 if (O_ONOCR(tty) && tty->column == 0)
367 goto break_out;
368 if (O_OCRNL(tty))
369 goto break_out;
370 tty->canon_column = tty->column = 0;
371 break;
372 case '\t':
373 goto break_out;
374 case '\b':
375 if (tty->column > 0)
376 tty->column--;
377 break;
378 default:
379 if (O_OLCUC(tty))
380 goto break_out;
381 if (!iscntrl(*cp))
382 tty->column++;
383 break;
386 break_out:
387 if (tty->driver->flush_chars)
388 tty->driver->flush_chars(tty);
389 i = tty->driver->write(tty, buf, i);
390 return i;
395 * put_char - write character to driver
396 * @c: character (or part of unicode symbol)
397 * @tty: terminal device
399 * Queue a byte to the driver layer for output
402 static inline void put_char(unsigned char c, struct tty_struct *tty)
404 tty->driver->put_char(tty, c);
408 * echo_char - echo characters
409 * @c: unicode byte to echo
410 * @tty: terminal device
412 * Echo user input back onto the screen. This must be called only when
413 * L_ECHO(tty) is true. Called from the driver receive_buf path.
416 static void echo_char(unsigned char c, struct tty_struct *tty)
418 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
419 put_char('^', tty);
420 put_char(c ^ 0100, tty);
421 tty->column += 2;
422 } else
423 opost(c, tty);
426 static inline void finish_erasing(struct tty_struct *tty)
428 if (tty->erasing) {
429 put_char('/', tty);
430 tty->column++;
431 tty->erasing = 0;
436 * eraser - handle erase function
437 * @c: character input
438 * @tty: terminal device
440 * Perform erase and neccessary output when an erase character is
441 * present in the stream from the driver layer. Handles the complexities
442 * of UTF-8 multibyte symbols.
445 static void eraser(unsigned char c, struct tty_struct *tty)
447 enum { ERASE, WERASE, KILL } kill_type;
448 int head, seen_alnums, cnt;
449 unsigned long flags;
451 if (tty->read_head == tty->canon_head) {
452 /* opost('\a', tty); */ /* what do you think? */
453 return;
455 if (c == ERASE_CHAR(tty))
456 kill_type = ERASE;
457 else if (c == WERASE_CHAR(tty))
458 kill_type = WERASE;
459 else {
460 if (!L_ECHO(tty)) {
461 spin_lock_irqsave(&tty->read_lock, flags);
462 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
463 (N_TTY_BUF_SIZE - 1));
464 tty->read_head = tty->canon_head;
465 spin_unlock_irqrestore(&tty->read_lock, flags);
466 return;
468 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
469 spin_lock_irqsave(&tty->read_lock, flags);
470 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
471 (N_TTY_BUF_SIZE - 1));
472 tty->read_head = tty->canon_head;
473 spin_unlock_irqrestore(&tty->read_lock, flags);
474 finish_erasing(tty);
475 echo_char(KILL_CHAR(tty), tty);
476 /* Add a newline if ECHOK is on and ECHOKE is off. */
477 if (L_ECHOK(tty))
478 opost('\n', tty);
479 return;
481 kill_type = KILL;
484 seen_alnums = 0;
485 while (tty->read_head != tty->canon_head) {
486 head = tty->read_head;
488 /* erase a single possibly multibyte character */
489 do {
490 head = (head - 1) & (N_TTY_BUF_SIZE-1);
491 c = tty->read_buf[head];
492 } while (is_continuation(c, tty) && head != tty->canon_head);
494 /* do not partially erase */
495 if (is_continuation(c, tty))
496 break;
498 if (kill_type == WERASE) {
499 /* Equivalent to BSD's ALTWERASE. */
500 if (isalnum(c) || c == '_')
501 seen_alnums++;
502 else if (seen_alnums)
503 break;
505 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
506 spin_lock_irqsave(&tty->read_lock, flags);
507 tty->read_head = head;
508 tty->read_cnt -= cnt;
509 spin_unlock_irqrestore(&tty->read_lock, flags);
510 if (L_ECHO(tty)) {
511 if (L_ECHOPRT(tty)) {
512 if (!tty->erasing) {
513 put_char('\\', tty);
514 tty->column++;
515 tty->erasing = 1;
517 /* if cnt > 1, output a multi-byte character */
518 echo_char(c, tty);
519 while (--cnt > 0) {
520 head = (head+1) & (N_TTY_BUF_SIZE-1);
521 put_char(tty->read_buf[head], tty);
523 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
524 echo_char(ERASE_CHAR(tty), tty);
525 } else if (c == '\t') {
526 unsigned int col = tty->canon_column;
527 unsigned long tail = tty->canon_head;
529 /* Find the column of the last char. */
530 while (tail != tty->read_head) {
531 c = tty->read_buf[tail];
532 if (c == '\t')
533 col = (col | 7) + 1;
534 else if (iscntrl(c)) {
535 if (L_ECHOCTL(tty))
536 col += 2;
537 } else if (!is_continuation(c, tty))
538 col++;
539 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
542 /* should never happen */
543 if (tty->column > 0x80000000)
544 tty->column = 0;
546 /* Now backup to that column. */
547 while (tty->column > col) {
548 /* Can't use opost here. */
549 put_char('\b', tty);
550 if (tty->column > 0)
551 tty->column--;
553 } else {
554 if (iscntrl(c) && L_ECHOCTL(tty)) {
555 put_char('\b', tty);
556 put_char(' ', tty);
557 put_char('\b', tty);
558 if (tty->column > 0)
559 tty->column--;
561 if (!iscntrl(c) || L_ECHOCTL(tty)) {
562 put_char('\b', tty);
563 put_char(' ', tty);
564 put_char('\b', tty);
565 if (tty->column > 0)
566 tty->column--;
570 if (kill_type == ERASE)
571 break;
573 if (tty->read_head == tty->canon_head)
574 finish_erasing(tty);
578 * isig - handle the ISIG optio
579 * @sig: signal
580 * @tty: terminal
581 * @flush: force flush
583 * Called when a signal is being sent due to terminal input. This
584 * may caus terminal flushing to take place according to the termios
585 * settings and character used. Called from the driver receive_buf
586 * path so serialized.
589 static inline void isig(int sig, struct tty_struct *tty, int flush)
591 if (tty->pgrp)
592 kill_pgrp(tty->pgrp, sig, 1);
593 if (flush || !L_NOFLSH(tty)) {
594 n_tty_flush_buffer(tty);
595 if (tty->driver->flush_buffer)
596 tty->driver->flush_buffer(tty);
601 * n_tty_receive_break - handle break
602 * @tty: terminal
604 * An RS232 break event has been hit in the incoming bitstream. This
605 * can cause a variety of events depending upon the termios settings.
607 * Called from the receive_buf path so single threaded.
610 static inline void n_tty_receive_break(struct tty_struct *tty)
612 if (I_IGNBRK(tty))
613 return;
614 if (I_BRKINT(tty)) {
615 isig(SIGINT, tty, 1);
616 return;
618 if (I_PARMRK(tty)) {
619 put_tty_queue('\377', tty);
620 put_tty_queue('\0', tty);
622 put_tty_queue('\0', tty);
623 wake_up_interruptible(&tty->read_wait);
627 * n_tty_receive_overrun - handle overrun reporting
628 * @tty: terminal
630 * Data arrived faster than we could process it. While the tty
631 * driver has flagged this the bits that were missed are gone
632 * forever.
634 * Called from the receive_buf path so single threaded. Does not
635 * need locking as num_overrun and overrun_time are function
636 * private.
639 static inline void n_tty_receive_overrun(struct tty_struct *tty)
641 char buf[64];
643 tty->num_overrun++;
644 if (time_before(tty->overrun_time, jiffies - HZ) ||
645 time_after(tty->overrun_time, jiffies)) {
646 printk(KERN_WARNING "%s: %d input overrun(s)\n",
647 tty_name(tty, buf),
648 tty->num_overrun);
649 tty->overrun_time = jiffies;
650 tty->num_overrun = 0;
655 * n_tty_receive_parity_error - error notifier
656 * @tty: terminal device
657 * @c: character
659 * Process a parity error and queue the right data to indicate
660 * the error case if neccessary. Locking as per n_tty_receive_buf.
662 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
663 unsigned char c)
665 if (I_IGNPAR(tty)) {
666 return;
668 if (I_PARMRK(tty)) {
669 put_tty_queue('\377', tty);
670 put_tty_queue('\0', tty);
671 put_tty_queue(c, tty);
672 } else if (I_INPCK(tty))
673 put_tty_queue('\0', tty);
674 else
675 put_tty_queue(c, tty);
676 wake_up_interruptible(&tty->read_wait);
680 * n_tty_receive_char - perform processing
681 * @tty: terminal device
682 * @c: character
684 * Process an individual character of input received from the driver.
685 * This is serialized with respect to itself by the rules for the
686 * driver above.
689 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
691 unsigned long flags;
693 if (tty->raw) {
694 put_tty_queue(c, tty);
695 return;
698 if (tty->stopped && !tty->flow_stopped &&
699 I_IXON(tty) && I_IXANY(tty)) {
700 start_tty(tty);
701 return;
704 if (I_ISTRIP(tty))
705 c &= 0x7f;
706 if (I_IUCLC(tty) && L_IEXTEN(tty))
707 c=tolower(c);
709 if (tty->closing) {
710 if (I_IXON(tty)) {
711 if (c == START_CHAR(tty))
712 start_tty(tty);
713 else if (c == STOP_CHAR(tty))
714 stop_tty(tty);
716 return;
720 * If the previous character was LNEXT, or we know that this
721 * character is not one of the characters that we'll have to
722 * handle specially, do shortcut processing to speed things
723 * up.
725 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
726 finish_erasing(tty);
727 tty->lnext = 0;
728 if (L_ECHO(tty)) {
729 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
730 put_char('\a', tty); /* beep if no space */
731 return;
733 /* Record the column of first canon char. */
734 if (tty->canon_head == tty->read_head)
735 tty->canon_column = tty->column;
736 echo_char(c, tty);
738 if (I_PARMRK(tty) && c == (unsigned char) '\377')
739 put_tty_queue(c, tty);
740 put_tty_queue(c, tty);
741 return;
744 if (c == '\r') {
745 if (I_IGNCR(tty))
746 return;
747 if (I_ICRNL(tty))
748 c = '\n';
749 } else if (c == '\n' && I_INLCR(tty))
750 c = '\r';
751 if (I_IXON(tty)) {
752 if (c == START_CHAR(tty)) {
753 start_tty(tty);
754 return;
756 if (c == STOP_CHAR(tty)) {
757 stop_tty(tty);
758 return;
761 if (L_ISIG(tty)) {
762 int signal;
763 signal = SIGINT;
764 if (c == INTR_CHAR(tty))
765 goto send_signal;
766 signal = SIGQUIT;
767 if (c == QUIT_CHAR(tty))
768 goto send_signal;
769 signal = SIGTSTP;
770 if (c == SUSP_CHAR(tty)) {
771 send_signal:
772 isig(signal, tty, 0);
773 return;
776 if (tty->icanon) {
777 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
778 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
779 eraser(c, tty);
780 return;
782 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
783 tty->lnext = 1;
784 if (L_ECHO(tty)) {
785 finish_erasing(tty);
786 if (L_ECHOCTL(tty)) {
787 put_char('^', tty);
788 put_char('\b', tty);
791 return;
793 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
794 L_IEXTEN(tty)) {
795 unsigned long tail = tty->canon_head;
797 finish_erasing(tty);
798 echo_char(c, tty);
799 opost('\n', tty);
800 while (tail != tty->read_head) {
801 echo_char(tty->read_buf[tail], tty);
802 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
804 return;
806 if (c == '\n') {
807 if (L_ECHO(tty) || L_ECHONL(tty)) {
808 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
809 put_char('\a', tty);
810 opost('\n', tty);
812 goto handle_newline;
814 if (c == EOF_CHAR(tty)) {
815 if (tty->canon_head != tty->read_head)
816 set_bit(TTY_PUSH, &tty->flags);
817 c = __DISABLED_CHAR;
818 goto handle_newline;
820 if ((c == EOL_CHAR(tty)) ||
821 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
823 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
825 if (L_ECHO(tty)) {
826 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
827 put_char('\a', tty);
828 /* Record the column of first canon char. */
829 if (tty->canon_head == tty->read_head)
830 tty->canon_column = tty->column;
831 echo_char(c, tty);
834 * XXX does PARMRK doubling happen for
835 * EOL_CHAR and EOL2_CHAR?
837 if (I_PARMRK(tty) && c == (unsigned char) '\377')
838 put_tty_queue(c, tty);
840 handle_newline:
841 spin_lock_irqsave(&tty->read_lock, flags);
842 set_bit(tty->read_head, tty->read_flags);
843 put_tty_queue_nolock(c, tty);
844 tty->canon_head = tty->read_head;
845 tty->canon_data++;
846 spin_unlock_irqrestore(&tty->read_lock, flags);
847 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
848 if (waitqueue_active(&tty->read_wait))
849 wake_up_interruptible(&tty->read_wait);
850 return;
854 finish_erasing(tty);
855 if (L_ECHO(tty)) {
856 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
857 put_char('\a', tty); /* beep if no space */
858 return;
860 if (c == '\n')
861 opost('\n', tty);
862 else {
863 /* Record the column of first canon char. */
864 if (tty->canon_head == tty->read_head)
865 tty->canon_column = tty->column;
866 echo_char(c, tty);
870 if (I_PARMRK(tty) && c == (unsigned char) '\377')
871 put_tty_queue(c, tty);
873 put_tty_queue(c, tty);
878 * n_tty_write_wakeup - asynchronous I/O notifier
879 * @tty: tty device
881 * Required for the ptys, serial driver etc. since processes
882 * that attach themselves to the master and rely on ASYNC
883 * IO must be woken up
886 static void n_tty_write_wakeup(struct tty_struct *tty)
888 if (tty->fasync)
890 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
891 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
893 return;
897 * n_tty_receive_buf - data receive
898 * @tty: terminal device
899 * @cp: buffer
900 * @fp: flag buffer
901 * @count: characters
903 * Called by the terminal driver when a block of characters has
904 * been received. This function must be called from soft contexts
905 * not from interrupt context. The driver is responsible for making
906 * calls one at a time and in order (or using flush_to_ldisc)
909 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
910 char *fp, int count)
912 const unsigned char *p;
913 char *f, flags = TTY_NORMAL;
914 int i;
915 char buf[64];
916 unsigned long cpuflags;
918 if (!tty->read_buf)
919 return;
921 if (tty->real_raw) {
922 spin_lock_irqsave(&tty->read_lock, cpuflags);
923 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
924 N_TTY_BUF_SIZE - tty->read_head);
925 i = min(count, i);
926 memcpy(tty->read_buf + tty->read_head, cp, i);
927 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
928 tty->read_cnt += i;
929 cp += i;
930 count -= i;
932 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
933 N_TTY_BUF_SIZE - tty->read_head);
934 i = min(count, i);
935 memcpy(tty->read_buf + tty->read_head, cp, i);
936 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
937 tty->read_cnt += i;
938 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
939 } else {
940 for (i=count, p = cp, f = fp; i; i--, p++) {
941 if (f)
942 flags = *f++;
943 switch (flags) {
944 case TTY_NORMAL:
945 n_tty_receive_char(tty, *p);
946 break;
947 case TTY_BREAK:
948 n_tty_receive_break(tty);
949 break;
950 case TTY_PARITY:
951 case TTY_FRAME:
952 n_tty_receive_parity_error(tty, *p);
953 break;
954 case TTY_OVERRUN:
955 n_tty_receive_overrun(tty);
956 break;
957 default:
958 printk("%s: unknown flag %d\n",
959 tty_name(tty, buf), flags);
960 break;
963 if (tty->driver->flush_chars)
964 tty->driver->flush_chars(tty);
967 n_tty_set_room(tty);
969 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
970 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
971 if (waitqueue_active(&tty->read_wait))
972 wake_up_interruptible(&tty->read_wait);
976 * Check the remaining room for the input canonicalization
977 * mode. We don't want to throttle the driver if we're in
978 * canonical mode and don't have a newline yet!
980 if (tty->receive_room < TTY_THRESHOLD_THROTTLE) {
981 /* check TTY_THROTTLED first so it indicates our state */
982 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
983 tty->driver->throttle)
984 tty->driver->throttle(tty);
988 int is_ignored(int sig)
990 return (sigismember(&current->blocked, sig) ||
991 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
995 * n_tty_set_termios - termios data changed
996 * @tty: terminal
997 * @old: previous data
999 * Called by the tty layer when the user changes termios flags so
1000 * that the line discipline can plan ahead. This function cannot sleep
1001 * and is protected from re-entry by the tty layer. The user is
1002 * guaranteed that this function will not be re-entered or in progress
1003 * when the ldisc is closed.
1006 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios * old)
1008 if (!tty)
1009 return;
1011 tty->icanon = (L_ICANON(tty) != 0);
1012 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1013 tty->raw = 1;
1014 tty->real_raw = 1;
1015 n_tty_set_room(tty);
1016 return;
1018 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1019 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1020 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1021 I_PARMRK(tty)) {
1022 memset(tty->process_char_map, 0, 256/8);
1024 if (I_IGNCR(tty) || I_ICRNL(tty))
1025 set_bit('\r', tty->process_char_map);
1026 if (I_INLCR(tty))
1027 set_bit('\n', tty->process_char_map);
1029 if (L_ICANON(tty)) {
1030 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1031 set_bit(KILL_CHAR(tty), tty->process_char_map);
1032 set_bit(EOF_CHAR(tty), tty->process_char_map);
1033 set_bit('\n', tty->process_char_map);
1034 set_bit(EOL_CHAR(tty), tty->process_char_map);
1035 if (L_IEXTEN(tty)) {
1036 set_bit(WERASE_CHAR(tty),
1037 tty->process_char_map);
1038 set_bit(LNEXT_CHAR(tty),
1039 tty->process_char_map);
1040 set_bit(EOL2_CHAR(tty),
1041 tty->process_char_map);
1042 if (L_ECHO(tty))
1043 set_bit(REPRINT_CHAR(tty),
1044 tty->process_char_map);
1047 if (I_IXON(tty)) {
1048 set_bit(START_CHAR(tty), tty->process_char_map);
1049 set_bit(STOP_CHAR(tty), tty->process_char_map);
1051 if (L_ISIG(tty)) {
1052 set_bit(INTR_CHAR(tty), tty->process_char_map);
1053 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1054 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1056 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1057 tty->raw = 0;
1058 tty->real_raw = 0;
1059 } else {
1060 tty->raw = 1;
1061 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1062 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1063 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1064 tty->real_raw = 1;
1065 else
1066 tty->real_raw = 0;
1068 n_tty_set_room(tty);
1072 * n_tty_close - close the ldisc for this tty
1073 * @tty: device
1075 * Called from the terminal layer when this line discipline is
1076 * being shut down, either because of a close or becsuse of a
1077 * discipline change. The function will not be called while other
1078 * ldisc methods are in progress.
1081 static void n_tty_close(struct tty_struct *tty)
1083 n_tty_flush_buffer(tty);
1084 if (tty->read_buf) {
1085 free_buf(tty->read_buf);
1086 tty->read_buf = NULL;
1091 * n_tty_open - open an ldisc
1092 * @tty: terminal to open
1094 * Called when this line discipline is being attached to the
1095 * terminal device. Can sleep. Called serialized so that no
1096 * other events will occur in parallel. No further open will occur
1097 * until a close.
1100 static int n_tty_open(struct tty_struct *tty)
1102 if (!tty)
1103 return -EINVAL;
1105 /* This one is ugly. Currently a malloc failure here can panic */
1106 if (!tty->read_buf) {
1107 tty->read_buf = alloc_buf();
1108 if (!tty->read_buf)
1109 return -ENOMEM;
1111 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1112 reset_buffer_flags(tty);
1113 tty->column = 0;
1114 n_tty_set_termios(tty, NULL);
1115 tty->minimum_to_wake = 1;
1116 tty->closing = 0;
1117 return 0;
1120 static inline int input_available_p(struct tty_struct *tty, int amt)
1122 if (tty->icanon) {
1123 if (tty->canon_data)
1124 return 1;
1125 } else if (tty->read_cnt >= (amt ? amt : 1))
1126 return 1;
1128 return 0;
1132 * copy_from_read_buf - copy read data directly
1133 * @tty: terminal device
1134 * @b: user data
1135 * @nr: size of data
1137 * Helper function to speed up read_chan. It is only called when
1138 * ICANON is off; it copies characters straight from the tty queue to
1139 * user space directly. It can be profitably called twice; once to
1140 * drain the space from the tail pointer to the (physical) end of the
1141 * buffer, and once to drain the space from the (physical) beginning of
1142 * the buffer to head pointer.
1144 * Called under the tty->atomic_read_lock sem
1148 static int copy_from_read_buf(struct tty_struct *tty,
1149 unsigned char __user **b,
1150 size_t *nr)
1153 int retval;
1154 size_t n;
1155 unsigned long flags;
1157 retval = 0;
1158 spin_lock_irqsave(&tty->read_lock, flags);
1159 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1160 n = min(*nr, n);
1161 spin_unlock_irqrestore(&tty->read_lock, flags);
1162 if (n) {
1163 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1164 n -= retval;
1165 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1166 spin_lock_irqsave(&tty->read_lock, flags);
1167 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1168 tty->read_cnt -= n;
1169 spin_unlock_irqrestore(&tty->read_lock, flags);
1170 *b += n;
1171 *nr -= n;
1173 return retval;
1176 extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *);
1179 * job_control - check job control
1180 * @tty: tty
1181 * @file: file handle
1183 * Perform job control management checks on this file/tty descriptor
1184 * and if appropriate send any needed signals and return a negative
1185 * error code if action should be taken.
1188 static int job_control(struct tty_struct *tty, struct file *file)
1190 /* Job control check -- must be done at start and after
1191 every sleep (POSIX.1 7.1.1.4). */
1192 /* NOTE: not yet done after every sleep pending a thorough
1193 check of the logic of this change. -- jlc */
1194 /* don't stop on /dev/console */
1195 if (file->f_op->write != redirected_tty_write &&
1196 current->signal->tty == tty) {
1197 if (!tty->pgrp)
1198 printk("read_chan: no tty->pgrp!\n");
1199 else if (task_pgrp(current) != tty->pgrp) {
1200 if (is_ignored(SIGTTIN) ||
1201 is_current_pgrp_orphaned())
1202 return -EIO;
1203 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1204 set_thread_flag(TIF_SIGPENDING);
1205 return -ERESTARTSYS;
1208 return 0;
1213 * read_chan - read function for tty
1214 * @tty: tty device
1215 * @file: file object
1216 * @buf: userspace buffer pointer
1217 * @nr: size of I/O
1219 * Perform reads for the line discipline. We are guaranteed that the
1220 * line discipline will not be closed under us but we may get multiple
1221 * parallel readers and must handle this ourselves. We may also get
1222 * a hangup. Always called in user context, may sleep.
1224 * This code must be sure never to sleep through a hangup.
1227 static ssize_t read_chan(struct tty_struct *tty, struct file *file,
1228 unsigned char __user *buf, size_t nr)
1230 unsigned char __user *b = buf;
1231 DECLARE_WAITQUEUE(wait, current);
1232 int c;
1233 int minimum, time;
1234 ssize_t retval = 0;
1235 ssize_t size;
1236 long timeout;
1237 unsigned long flags;
1239 do_it_again:
1241 if (!tty->read_buf) {
1242 printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
1243 return -EIO;
1246 c = job_control(tty, file);
1247 if(c < 0)
1248 return c;
1250 minimum = time = 0;
1251 timeout = MAX_SCHEDULE_TIMEOUT;
1252 if (!tty->icanon) {
1253 time = (HZ / 10) * TIME_CHAR(tty);
1254 minimum = MIN_CHAR(tty);
1255 if (minimum) {
1256 if (time)
1257 tty->minimum_to_wake = 1;
1258 else if (!waitqueue_active(&tty->read_wait) ||
1259 (tty->minimum_to_wake > minimum))
1260 tty->minimum_to_wake = minimum;
1261 } else {
1262 timeout = 0;
1263 if (time) {
1264 timeout = time;
1265 time = 0;
1267 tty->minimum_to_wake = minimum = 1;
1272 * Internal serialization of reads.
1274 if (file->f_flags & O_NONBLOCK) {
1275 if (!mutex_trylock(&tty->atomic_read_lock))
1276 return -EAGAIN;
1278 else {
1279 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1280 return -ERESTARTSYS;
1283 add_wait_queue(&tty->read_wait, &wait);
1284 while (nr) {
1285 /* First test for status change. */
1286 if (tty->packet && tty->link->ctrl_status) {
1287 unsigned char cs;
1288 if (b != buf)
1289 break;
1290 cs = tty->link->ctrl_status;
1291 tty->link->ctrl_status = 0;
1292 if (tty_put_user(tty, cs, b++)) {
1293 retval = -EFAULT;
1294 b--;
1295 break;
1297 nr--;
1298 break;
1300 /* This statement must be first before checking for input
1301 so that any interrupt will set the state back to
1302 TASK_RUNNING. */
1303 set_current_state(TASK_INTERRUPTIBLE);
1305 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1306 ((minimum - (b - buf)) >= 1))
1307 tty->minimum_to_wake = (minimum - (b - buf));
1309 if (!input_available_p(tty, 0)) {
1310 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1311 retval = -EIO;
1312 break;
1314 if (tty_hung_up_p(file))
1315 break;
1316 if (!timeout)
1317 break;
1318 if (file->f_flags & O_NONBLOCK) {
1319 retval = -EAGAIN;
1320 break;
1322 if (signal_pending(current)) {
1323 retval = -ERESTARTSYS;
1324 break;
1326 n_tty_set_room(tty);
1327 timeout = schedule_timeout(timeout);
1328 continue;
1330 __set_current_state(TASK_RUNNING);
1332 /* Deal with packet mode. */
1333 if (tty->packet && b == buf) {
1334 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1335 retval = -EFAULT;
1336 b--;
1337 break;
1339 nr--;
1342 if (tty->icanon) {
1343 /* N.B. avoid overrun if nr == 0 */
1344 while (nr && tty->read_cnt) {
1345 int eol;
1347 eol = test_and_clear_bit(tty->read_tail,
1348 tty->read_flags);
1349 c = tty->read_buf[tty->read_tail];
1350 spin_lock_irqsave(&tty->read_lock, flags);
1351 tty->read_tail = ((tty->read_tail+1) &
1352 (N_TTY_BUF_SIZE-1));
1353 tty->read_cnt--;
1354 if (eol) {
1355 /* this test should be redundant:
1356 * we shouldn't be reading data if
1357 * canon_data is 0
1359 if (--tty->canon_data < 0)
1360 tty->canon_data = 0;
1362 spin_unlock_irqrestore(&tty->read_lock, flags);
1364 if (!eol || (c != __DISABLED_CHAR)) {
1365 if (tty_put_user(tty, c, b++)) {
1366 retval = -EFAULT;
1367 b--;
1368 break;
1370 nr--;
1372 if (eol) {
1373 tty_audit_push(tty);
1374 break;
1377 if (retval)
1378 break;
1379 } else {
1380 int uncopied;
1381 uncopied = copy_from_read_buf(tty, &b, &nr);
1382 uncopied += copy_from_read_buf(tty, &b, &nr);
1383 if (uncopied) {
1384 retval = -EFAULT;
1385 break;
1389 /* If there is enough space in the read buffer now, let the
1390 * low-level driver know. We use n_tty_chars_in_buffer() to
1391 * check the buffer, as it now knows about canonical mode.
1392 * Otherwise, if the driver is throttled and the line is
1393 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1394 * we won't get any more characters.
1396 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1397 n_tty_set_room(tty);
1398 check_unthrottle(tty);
1401 if (b - buf >= minimum)
1402 break;
1403 if (time)
1404 timeout = time;
1406 mutex_unlock(&tty->atomic_read_lock);
1407 remove_wait_queue(&tty->read_wait, &wait);
1409 if (!waitqueue_active(&tty->read_wait))
1410 tty->minimum_to_wake = minimum;
1412 __set_current_state(TASK_RUNNING);
1413 size = b - buf;
1414 if (size) {
1415 retval = size;
1416 if (nr)
1417 clear_bit(TTY_PUSH, &tty->flags);
1418 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1419 goto do_it_again;
1421 n_tty_set_room(tty);
1423 return retval;
1427 * write_chan - write function for tty
1428 * @tty: tty device
1429 * @file: file object
1430 * @buf: userspace buffer pointer
1431 * @nr: size of I/O
1433 * Write function of the terminal device. This is serialized with
1434 * respect to other write callers but not to termios changes, reads
1435 * and other such events. We must be careful with N_TTY as the receive
1436 * code will echo characters, thus calling driver write methods.
1438 * This code must be sure never to sleep through a hangup.
1441 static ssize_t write_chan(struct tty_struct * tty, struct file * file,
1442 const unsigned char * buf, size_t nr)
1444 const unsigned char *b = buf;
1445 DECLARE_WAITQUEUE(wait, current);
1446 int c;
1447 ssize_t retval = 0;
1449 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1450 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1451 retval = tty_check_change(tty);
1452 if (retval)
1453 return retval;
1456 add_wait_queue(&tty->write_wait, &wait);
1457 while (1) {
1458 set_current_state(TASK_INTERRUPTIBLE);
1459 if (signal_pending(current)) {
1460 retval = -ERESTARTSYS;
1461 break;
1463 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1464 retval = -EIO;
1465 break;
1467 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1468 while (nr > 0) {
1469 ssize_t num = opost_block(tty, b, nr);
1470 if (num < 0) {
1471 if (num == -EAGAIN)
1472 break;
1473 retval = num;
1474 goto break_out;
1476 b += num;
1477 nr -= num;
1478 if (nr == 0)
1479 break;
1480 c = *b;
1481 if (opost(c, tty) < 0)
1482 break;
1483 b++; nr--;
1485 if (tty->driver->flush_chars)
1486 tty->driver->flush_chars(tty);
1487 } else {
1488 while (nr > 0) {
1489 c = tty->driver->write(tty, b, nr);
1490 if (c < 0) {
1491 retval = c;
1492 goto break_out;
1494 if (!c)
1495 break;
1496 b += c;
1497 nr -= c;
1500 if (!nr)
1501 break;
1502 if (file->f_flags & O_NONBLOCK) {
1503 retval = -EAGAIN;
1504 break;
1506 schedule();
1508 break_out:
1509 __set_current_state(TASK_RUNNING);
1510 remove_wait_queue(&tty->write_wait, &wait);
1511 return (b - buf) ? b - buf : retval;
1515 * normal_poll - poll method for N_TTY
1516 * @tty: terminal device
1517 * @file: file accessing it
1518 * @wait: poll table
1520 * Called when the line discipline is asked to poll() for data or
1521 * for special events. This code is not serialized with respect to
1522 * other events save open/close.
1524 * This code must be sure never to sleep through a hangup.
1525 * Called without the kernel lock held - fine
1527 * FIXME: if someone changes the VMIN or discipline settings for the
1528 * terminal while another process is in poll() the poll does not
1529 * recompute the new limits. Possibly set_termios should issue
1530 * a read wakeup to fix this bug.
1533 static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait)
1535 unsigned int mask = 0;
1537 poll_wait(file, &tty->read_wait, wait);
1538 poll_wait(file, &tty->write_wait, wait);
1539 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1540 mask |= POLLIN | POLLRDNORM;
1541 if (tty->packet && tty->link->ctrl_status)
1542 mask |= POLLPRI | POLLIN | POLLRDNORM;
1543 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1544 mask |= POLLHUP;
1545 if (tty_hung_up_p(file))
1546 mask |= POLLHUP;
1547 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1548 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1549 tty->minimum_to_wake = MIN_CHAR(tty);
1550 else
1551 tty->minimum_to_wake = 1;
1553 if (!tty_is_writelocked(tty) &&
1554 tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
1555 tty->driver->write_room(tty) > 0)
1556 mask |= POLLOUT | POLLWRNORM;
1557 return mask;
1560 struct tty_ldisc tty_ldisc_N_TTY = {
1561 .magic = TTY_LDISC_MAGIC,
1562 .name = "n_tty",
1563 .open = n_tty_open,
1564 .close = n_tty_close,
1565 .flush_buffer = n_tty_flush_buffer,
1566 .chars_in_buffer = n_tty_chars_in_buffer,
1567 .read = read_chan,
1568 .write = write_chan,
1569 .ioctl = n_tty_ioctl,
1570 .set_termios = n_tty_set_termios,
1571 .poll = normal_poll,
1572 .receive_buf = n_tty_receive_buf,
1573 .write_wakeup = n_tty_write_wakeup