2 * n_tty.c --- implements the N_TTY line discipline.
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,
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
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
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>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
49 #include <asm/uaccess.h>
50 #include <asm/system.h>
52 /* number of characters left in xmit buffer before select has we have room */
53 #define WAKEUP_CHARS 256
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.
60 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
61 #define TTY_THRESHOLD_UNTHROTTLE 128
63 static inline unsigned char *alloc_buf(void)
65 int prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
67 if (PAGE_SIZE != N_TTY_BUF_SIZE)
68 return kmalloc(N_TTY_BUF_SIZE, prio);
70 return (unsigned char *)__get_free_page(prio);
73 static inline void free_buf(unsigned char *buf)
75 if (PAGE_SIZE != N_TTY_BUF_SIZE)
78 free_page((unsigned long) buf);
81 static inline void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
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);
90 static inline void put_tty_queue(unsigned char c, struct tty_struct *tty)
94 * The problem of stomping on the buffers ends here.
95 * Why didn't anyone see this one coming? --AJK
97 spin_lock_irqsave(&tty->read_lock, flags);
98 put_tty_queue_nolock(c, tty);
99 spin_unlock_irqrestore(&tty->read_lock, flags);
103 * check_unthrottle - allow new receive data
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.
114 static void check_unthrottle(struct tty_struct * tty)
117 test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
118 tty->driver->unthrottle)
119 tty->driver->unthrottle(tty);
123 * reset_buffer_flags - reset buffer state
124 * @tty: terminal to reset
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().
130 static void reset_buffer_flags(struct tty_struct *tty)
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);
143 * n_tty_flush_buffer - clean input queue
144 * @tty: terminal device
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).
151 * FIXME: tty->ctrl_status is not spinlocked and relies on
152 * lock_kernel() still.
155 static void n_tty_flush_buffer(struct tty_struct * tty)
157 /* clear everything and unthrottle the driver */
158 reset_buffer_flags(tty);
163 if (tty->link->packet) {
164 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
165 wake_up_interruptible(&tty->link->read_wait);
170 * n_tty_chars_in_buffer - report available bytes
173 * Report the number of characters buffered to be delivered to user
174 * at this instant in time.
177 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
182 spin_lock_irqsave(&tty->read_lock, flags);
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);
190 spin_unlock_irqrestore(&tty->read_lock, flags);
195 * is_utf8_continuation - utf8 multibyte check
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
203 static inline int is_utf8_continuation(unsigned char c)
205 return (c & 0xc0) == 0x80;
209 * is_continuation - multibyte check
212 * Returns true if the utf8 character 'c' is a multibyte continuation
213 * character and the terminal is in unicode mode.
216 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
218 return I_IUTF8(tty) && is_utf8_continuation(c);
222 * opost - output post processor
223 * @c: character (or partial unicode symbol)
224 * @tty: terminal device
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.
231 * Called from both the receive and transmit sides and can be called
232 * re-entrantly. Relies on lock_kernel() still.
235 static int opost(unsigned char c, struct tty_struct *tty)
239 space = tty->driver->write_room(tty);
251 tty->driver->put_char(tty, '\r');
254 tty->canon_column = tty->column;
257 if (O_ONOCR(tty) && tty->column == 0)
262 tty->canon_column = tty->column = 0;
265 tty->canon_column = tty->column = 0;
268 spaces = 8 - (tty->column & 7);
269 if (O_TABDLY(tty) == XTABS) {
272 tty->column += spaces;
273 tty->driver->write(tty, " ", spaces);
276 tty->column += spaces;
285 if (!iscntrl(c) && !is_continuation(c, tty))
290 tty->driver->put_char(tty, c);
295 * opost_block - block postprocess
296 * @tty: terminal device
297 * @inbuf: user buffer
298 * @nr: number of bytes
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.
305 * Called from write_chan under the tty layer write lock.
308 static ssize_t opost_block(struct tty_struct * tty,
309 const unsigned char * buf, unsigned int nr)
313 const unsigned char *cp;
315 space = tty->driver->write_room(tty);
321 for (i = 0, cp = buf; i < nr; i++, cp++) {
328 tty->canon_column = tty->column;
331 if (O_ONOCR(tty) && tty->column == 0)
335 tty->canon_column = tty->column = 0;
352 if (tty->driver->flush_chars)
353 tty->driver->flush_chars(tty);
354 i = tty->driver->write(tty, buf, i);
360 * put_char - write character to driver
361 * @c: character (or part of unicode symbol)
362 * @tty: terminal device
364 * Queue a byte to the driver layer for output
367 static inline void put_char(unsigned char c, struct tty_struct *tty)
369 tty->driver->put_char(tty, c);
373 * echo_char - echo characters
374 * @c: unicode byte to echo
375 * @tty: terminal device
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.
381 static void echo_char(unsigned char c, struct tty_struct *tty)
383 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
385 put_char(c ^ 0100, tty);
391 static inline void finish_erasing(struct tty_struct *tty)
401 * eraser - handle erase function
402 * @c: character input
403 * @tty: terminal device
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.
410 static void eraser(unsigned char c, struct tty_struct *tty)
412 enum { ERASE, WERASE, KILL } kill_type;
413 int head, seen_alnums, cnt;
416 if (tty->read_head == tty->canon_head) {
417 /* opost('\a', tty); */ /* what do you think? */
420 if (c == ERASE_CHAR(tty))
422 else if (c == WERASE_CHAR(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);
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);
440 echo_char(KILL_CHAR(tty), tty);
441 /* Add a newline if ECHOK is on and ECHOKE is off. */
450 while (tty->read_head != tty->canon_head) {
451 head = tty->read_head;
453 /* erase a single possibly multibyte character */
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);
459 /* do not partially erase */
460 if (is_continuation(c, tty))
463 if (kill_type == WERASE) {
464 /* Equivalent to BSD's ALTWERASE. */
465 if (isalnum(c) || c == '_')
467 else if (seen_alnums)
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);
476 if (L_ECHOPRT(tty)) {
482 /* if cnt > 1, output a multi-byte character */
485 head = (head+1) & (N_TTY_BUF_SIZE-1);
486 put_char(tty->read_buf[head], tty);
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;
494 /* Find the column of the last char. */
495 while (tail != tty->read_head) {
496 c = tty->read_buf[tail];
499 else if (iscntrl(c)) {
502 } else if (!is_continuation(c, tty))
504 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
507 /* should never happen */
508 if (tty->column > 0x80000000)
511 /* Now backup to that column. */
512 while (tty->column > col) {
513 /* Can't use opost here. */
519 if (iscntrl(c) && L_ECHOCTL(tty)) {
526 if (!iscntrl(c) || L_ECHOCTL(tty)) {
535 if (kill_type == ERASE)
538 if (tty->read_head == tty->canon_head)
543 * isig - handle the ISIG optio
546 * @flush: force flush
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.
554 static inline void isig(int sig, struct tty_struct *tty, int flush)
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);
566 * n_tty_receive_break - handle break
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.
572 * Called from the receive_buf path so single threaded.
575 static inline void n_tty_receive_break(struct tty_struct *tty)
580 isig(SIGINT, tty, 1);
584 put_tty_queue('\377', tty);
585 put_tty_queue('\0', tty);
587 put_tty_queue('\0', tty);
588 wake_up_interruptible(&tty->read_wait);
592 * n_tty_receive_overrun - handle overrun reporting
595 * Data arrived faster than we could process it. While the tty
596 * driver has flagged this the bits that were missed are gone
599 * Called from the receive_buf path so single threaded. Does not
600 * need locking as num_overrun and overrun_time are function
604 static inline void n_tty_receive_overrun(struct tty_struct *tty)
609 if (time_before(tty->overrun_time, jiffies - HZ)) {
610 printk(KERN_WARNING "%s: %d input overrun(s)\n", tty_name(tty, buf),
612 tty->overrun_time = jiffies;
613 tty->num_overrun = 0;
618 * n_tty_receive_parity_error - error notifier
619 * @tty: terminal device
622 * Process a parity error and queue the right data to indicate
623 * the error case if neccessary. Locking as per n_tty_receive_buf.
625 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
632 put_tty_queue('\377', tty);
633 put_tty_queue('\0', tty);
634 put_tty_queue(c, tty);
635 } else if (I_INPCK(tty))
636 put_tty_queue('\0', tty);
638 put_tty_queue(c, tty);
639 wake_up_interruptible(&tty->read_wait);
643 * n_tty_receive_char - perform processing
644 * @tty: terminal device
647 * Process an individual character of input received from the driver.
648 * This is serialized with respect to itself by the rules for the
652 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
657 put_tty_queue(c, tty);
661 if (tty->stopped && !tty->flow_stopped &&
662 I_IXON(tty) && I_IXANY(tty)) {
669 if (I_IUCLC(tty) && L_IEXTEN(tty))
674 if (c == START_CHAR(tty))
676 else if (c == STOP_CHAR(tty))
683 * If the previous character was LNEXT, or we know that this
684 * character is not one of the characters that we'll have to
685 * handle specially, do shortcut processing to speed things
688 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
692 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
693 put_char('\a', tty); /* beep if no space */
696 /* Record the column of first canon char. */
697 if (tty->canon_head == tty->read_head)
698 tty->canon_column = tty->column;
701 if (I_PARMRK(tty) && c == (unsigned char) '\377')
702 put_tty_queue(c, tty);
703 put_tty_queue(c, tty);
712 } else if (c == '\n' && I_INLCR(tty))
715 if (c == START_CHAR(tty)) {
719 if (c == STOP_CHAR(tty)) {
727 if (c == INTR_CHAR(tty))
730 if (c == QUIT_CHAR(tty))
733 if (c == SUSP_CHAR(tty)) {
735 isig(signal, tty, 0);
740 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
741 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
745 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
749 if (L_ECHOCTL(tty)) {
756 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
758 unsigned long tail = tty->canon_head;
763 while (tail != tty->read_head) {
764 echo_char(tty->read_buf[tail], tty);
765 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
770 if (L_ECHO(tty) || L_ECHONL(tty)) {
771 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
779 if (c == EOF_CHAR(tty)) {
780 if (tty->canon_head != tty->read_head)
781 set_bit(TTY_PUSH, &tty->flags);
785 if ((c == EOL_CHAR(tty)) ||
786 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
788 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
791 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
795 /* Record the column of first canon char. */
796 if (tty->canon_head == tty->read_head)
797 tty->canon_column = tty->column;
801 * XXX does PARMRK doubling happen for
802 * EOL_CHAR and EOL2_CHAR?
804 if (I_PARMRK(tty) && c == (unsigned char) '\377')
805 put_tty_queue(c, tty);
808 spin_lock_irqsave(&tty->read_lock, flags);
809 set_bit(tty->read_head, tty->read_flags);
810 put_tty_queue_nolock(c, tty);
811 tty->canon_head = tty->read_head;
813 spin_unlock_irqrestore(&tty->read_lock, flags);
814 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
815 if (waitqueue_active(&tty->read_wait))
816 wake_up_interruptible(&tty->read_wait);
823 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
824 put_char('\a', tty); /* beep if no space */
830 /* Record the column of first canon char. */
831 if (tty->canon_head == tty->read_head)
832 tty->canon_column = tty->column;
837 if (I_PARMRK(tty) && c == (unsigned char) '\377')
838 put_tty_queue(c, tty);
840 put_tty_queue(c, tty);
844 * n_tty_receive_room - receive space
847 * Called by the driver to find out how much data it is
848 * permitted to feed to the line discipline without any being lost
849 * and thus to manage flow control. Not serialized. Answers for the
853 static int n_tty_receive_room(struct tty_struct *tty)
855 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
858 * If we are doing input canonicalization, and there are no
859 * pending newlines, let characters through without limit, so
860 * that erase characters will be handled. Other excess
861 * characters will be beeped.
863 if (tty->icanon && !tty->canon_data)
864 return N_TTY_BUF_SIZE;
872 * n_tty_write_wakeup - asynchronous I/O notifier
875 * Required for the ptys, serial driver etc. since processes
876 * that attach themselves to the master and rely on ASYNC
877 * IO must be woken up
880 static void n_tty_write_wakeup(struct tty_struct *tty)
884 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
885 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
891 * n_tty_receive_buf - data receive
892 * @tty: terminal device
897 * Called by the terminal driver when a block of characters has
898 * been received. This function must be called from soft contexts
899 * not from interrupt context. The driver is responsible for making
900 * calls one at a time and in order (or using flush_to_ldisc)
903 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
906 const unsigned char *p;
907 char *f, flags = TTY_NORMAL;
910 unsigned long cpuflags;
916 spin_lock_irqsave(&tty->read_lock, cpuflags);
917 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
918 N_TTY_BUF_SIZE - tty->read_head);
920 memcpy(tty->read_buf + tty->read_head, cp, i);
921 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
926 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
927 N_TTY_BUF_SIZE - tty->read_head);
929 memcpy(tty->read_buf + tty->read_head, cp, i);
930 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
932 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
934 for (i=count, p = cp, f = fp; i; i--, p++) {
939 n_tty_receive_char(tty, *p);
942 n_tty_receive_break(tty);
946 n_tty_receive_parity_error(tty, *p);
949 n_tty_receive_overrun(tty);
952 printk("%s: unknown flag %d\n",
953 tty_name(tty, buf), flags);
957 if (tty->driver->flush_chars)
958 tty->driver->flush_chars(tty);
961 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
962 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
963 if (waitqueue_active(&tty->read_wait))
964 wake_up_interruptible(&tty->read_wait);
968 * Check the remaining room for the input canonicalization
969 * mode. We don't want to throttle the driver if we're in
970 * canonical mode and don't have a newline yet!
972 if (n_tty_receive_room(tty) < TTY_THRESHOLD_THROTTLE) {
973 /* check TTY_THROTTLED first so it indicates our state */
974 if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
975 tty->driver->throttle)
976 tty->driver->throttle(tty);
980 int is_ignored(int sig)
982 return (sigismember(¤t->blocked, sig) ||
983 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
987 * n_tty_set_termios - termios data changed
989 * @old: previous data
991 * Called by the tty layer when the user changes termios flags so
992 * that the line discipline can plan ahead. This function cannot sleep
993 * and is protected from re-entry by the tty layer. The user is
994 * guaranteed that this function will not be re-entered or in progress
995 * when the ldisc is closed.
998 static void n_tty_set_termios(struct tty_struct *tty, struct termios * old)
1003 tty->icanon = (L_ICANON(tty) != 0);
1004 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1009 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1010 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1011 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1013 memset(tty->process_char_map, 0, 256/8);
1015 if (I_IGNCR(tty) || I_ICRNL(tty))
1016 set_bit('\r', tty->process_char_map);
1018 set_bit('\n', tty->process_char_map);
1020 if (L_ICANON(tty)) {
1021 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1022 set_bit(KILL_CHAR(tty), tty->process_char_map);
1023 set_bit(EOF_CHAR(tty), tty->process_char_map);
1024 set_bit('\n', tty->process_char_map);
1025 set_bit(EOL_CHAR(tty), tty->process_char_map);
1026 if (L_IEXTEN(tty)) {
1027 set_bit(WERASE_CHAR(tty),
1028 tty->process_char_map);
1029 set_bit(LNEXT_CHAR(tty),
1030 tty->process_char_map);
1031 set_bit(EOL2_CHAR(tty),
1032 tty->process_char_map);
1034 set_bit(REPRINT_CHAR(tty),
1035 tty->process_char_map);
1039 set_bit(START_CHAR(tty), tty->process_char_map);
1040 set_bit(STOP_CHAR(tty), tty->process_char_map);
1043 set_bit(INTR_CHAR(tty), tty->process_char_map);
1044 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1045 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1047 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1052 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1053 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1054 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1062 * n_tty_close - close the ldisc for this tty
1065 * Called from the terminal layer when this line discipline is
1066 * being shut down, either because of a close or becsuse of a
1067 * discipline change. The function will not be called while other
1068 * ldisc methods are in progress.
1071 static void n_tty_close(struct tty_struct *tty)
1073 n_tty_flush_buffer(tty);
1074 if (tty->read_buf) {
1075 free_buf(tty->read_buf);
1076 tty->read_buf = NULL;
1081 * n_tty_open - open an ldisc
1082 * @tty: terminal to open
1084 * Called when this line discipline is being attached to the
1085 * terminal device. Can sleep. Called serialized so that no
1086 * other events will occur in parallel. No further open will occur
1090 static int n_tty_open(struct tty_struct *tty)
1095 /* This one is ugly. Currently a malloc failure here can panic */
1096 if (!tty->read_buf) {
1097 tty->read_buf = alloc_buf();
1101 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1102 reset_buffer_flags(tty);
1104 n_tty_set_termios(tty, NULL);
1105 tty->minimum_to_wake = 1;
1110 static inline int input_available_p(struct tty_struct *tty, int amt)
1113 if (tty->canon_data)
1115 } else if (tty->read_cnt >= (amt ? amt : 1))
1122 * copy_from_read_buf - copy read data directly
1123 * @tty: terminal device
1127 * Helper function to speed up read_chan. It is only called when
1128 * ICANON is off; it copies characters straight from the tty queue to
1129 * user space directly. It can be profitably called twice; once to
1130 * drain the space from the tail pointer to the (physical) end of the
1131 * buffer, and once to drain the space from the (physical) beginning of
1132 * the buffer to head pointer.
1134 * Called under the tty->atomic_read sem and with TTY_DONT_FLIP set
1138 static inline int copy_from_read_buf(struct tty_struct *tty,
1139 unsigned char __user **b,
1145 unsigned long flags;
1148 spin_lock_irqsave(&tty->read_lock, flags);
1149 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1151 spin_unlock_irqrestore(&tty->read_lock, flags);
1154 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1156 spin_lock_irqsave(&tty->read_lock, flags);
1157 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1159 spin_unlock_irqrestore(&tty->read_lock, flags);
1166 extern ssize_t redirected_tty_write(struct file *,const char *,size_t,loff_t *);
1169 * job_control - check job control
1171 * @file: file handle
1173 * Perform job control management checks on this file/tty descriptor
1174 * and if appropriate send any needed signals and return a negative
1175 * error code if action should be taken.
1178 static int job_control(struct tty_struct *tty, struct file *file)
1180 /* Job control check -- must be done at start and after
1181 every sleep (POSIX.1 7.1.1.4). */
1182 /* NOTE: not yet done after every sleep pending a thorough
1183 check of the logic of this change. -- jlc */
1184 /* don't stop on /dev/console */
1185 if (file->f_op->write != redirected_tty_write &&
1186 current->signal->tty == tty) {
1188 printk("read_chan: tty->pgrp <= 0!\n");
1189 else if (process_group(current) != tty->pgrp) {
1190 if (is_ignored(SIGTTIN) ||
1191 is_orphaned_pgrp(process_group(current)))
1193 kill_pg(process_group(current), SIGTTIN, 1);
1194 return -ERESTARTSYS;
1202 * read_chan - read function for tty
1204 * @file: file object
1205 * @buf: userspace buffer pointer
1208 * Perform reads for the line discipline. We are guaranteed that the
1209 * line discipline will not be closed under us but we may get multiple
1210 * parallel readers and must handle this ourselves. We may also get
1211 * a hangup. Always called in user context, may sleep.
1213 * This code must be sure never to sleep through a hangup.
1216 static ssize_t read_chan(struct tty_struct *tty, struct file *file,
1217 unsigned char __user *buf, size_t nr)
1219 unsigned char __user *b = buf;
1220 DECLARE_WAITQUEUE(wait, current);
1226 unsigned long flags;
1230 if (!tty->read_buf) {
1231 printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
1235 c = job_control(tty, file);
1240 timeout = MAX_SCHEDULE_TIMEOUT;
1242 time = (HZ / 10) * TIME_CHAR(tty);
1243 minimum = MIN_CHAR(tty);
1246 tty->minimum_to_wake = 1;
1247 else if (!waitqueue_active(&tty->read_wait) ||
1248 (tty->minimum_to_wake > minimum))
1249 tty->minimum_to_wake = minimum;
1256 tty->minimum_to_wake = minimum = 1;
1261 * Internal serialization of reads.
1263 if (file->f_flags & O_NONBLOCK) {
1264 if (down_trylock(&tty->atomic_read))
1268 if (down_interruptible(&tty->atomic_read))
1269 return -ERESTARTSYS;
1272 add_wait_queue(&tty->read_wait, &wait);
1273 set_bit(TTY_DONT_FLIP, &tty->flags);
1275 /* First test for status change. */
1276 if (tty->packet && tty->link->ctrl_status) {
1280 cs = tty->link->ctrl_status;
1281 tty->link->ctrl_status = 0;
1282 if (put_user(cs, b++)) {
1290 /* This statement must be first before checking for input
1291 so that any interrupt will set the state back to
1293 set_current_state(TASK_INTERRUPTIBLE);
1295 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1296 ((minimum - (b - buf)) >= 1))
1297 tty->minimum_to_wake = (minimum - (b - buf));
1299 if (!input_available_p(tty, 0)) {
1300 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1304 if (tty_hung_up_p(file))
1308 if (file->f_flags & O_NONBLOCK) {
1312 if (signal_pending(current)) {
1313 retval = -ERESTARTSYS;
1316 clear_bit(TTY_DONT_FLIP, &tty->flags);
1317 timeout = schedule_timeout(timeout);
1318 set_bit(TTY_DONT_FLIP, &tty->flags);
1321 __set_current_state(TASK_RUNNING);
1323 /* Deal with packet mode. */
1324 if (tty->packet && b == buf) {
1325 if (put_user(TIOCPKT_DATA, b++)) {
1334 /* N.B. avoid overrun if nr == 0 */
1335 while (nr && tty->read_cnt) {
1338 eol = test_and_clear_bit(tty->read_tail,
1340 c = tty->read_buf[tty->read_tail];
1341 spin_lock_irqsave(&tty->read_lock, flags);
1342 tty->read_tail = ((tty->read_tail+1) &
1343 (N_TTY_BUF_SIZE-1));
1346 /* this test should be redundant:
1347 * we shouldn't be reading data if
1350 if (--tty->canon_data < 0)
1351 tty->canon_data = 0;
1353 spin_unlock_irqrestore(&tty->read_lock, flags);
1355 if (!eol || (c != __DISABLED_CHAR)) {
1356 if (put_user(c, b++)) {
1370 uncopied = copy_from_read_buf(tty, &b, &nr);
1371 uncopied += copy_from_read_buf(tty, &b, &nr);
1378 /* If there is enough space in the read buffer now, let the
1379 * low-level driver know. We use n_tty_chars_in_buffer() to
1380 * check the buffer, as it now knows about canonical mode.
1381 * Otherwise, if the driver is throttled and the line is
1382 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1383 * we won't get any more characters.
1385 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE)
1386 check_unthrottle(tty);
1388 if (b - buf >= minimum)
1393 clear_bit(TTY_DONT_FLIP, &tty->flags);
1394 up(&tty->atomic_read);
1395 remove_wait_queue(&tty->read_wait, &wait);
1397 if (!waitqueue_active(&tty->read_wait))
1398 tty->minimum_to_wake = minimum;
1400 __set_current_state(TASK_RUNNING);
1405 clear_bit(TTY_PUSH, &tty->flags);
1406 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1413 * write_chan - write function for tty
1415 * @file: file object
1416 * @buf: userspace buffer pointer
1419 * Write function of the terminal device. This is serialized with
1420 * respect to other write callers but not to termios changes, reads
1421 * and other such events. We must be careful with N_TTY as the receive
1422 * code will echo characters, thus calling driver write methods.
1424 * This code must be sure never to sleep through a hangup.
1427 static ssize_t write_chan(struct tty_struct * tty, struct file * file,
1428 const unsigned char * buf, size_t nr)
1430 const unsigned char *b = buf;
1431 DECLARE_WAITQUEUE(wait, current);
1435 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1436 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1437 retval = tty_check_change(tty);
1442 add_wait_queue(&tty->write_wait, &wait);
1444 set_current_state(TASK_INTERRUPTIBLE);
1445 if (signal_pending(current)) {
1446 retval = -ERESTARTSYS;
1449 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1453 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1455 ssize_t num = opost_block(tty, b, nr);
1467 if (opost(c, tty) < 0)
1471 if (tty->driver->flush_chars)
1472 tty->driver->flush_chars(tty);
1474 c = tty->driver->write(tty, b, nr);
1484 if (file->f_flags & O_NONBLOCK) {
1491 __set_current_state(TASK_RUNNING);
1492 remove_wait_queue(&tty->write_wait, &wait);
1493 return (b - buf) ? b - buf : retval;
1497 * normal_poll - poll method for N_TTY
1498 * @tty: terminal device
1499 * @file: file accessing it
1502 * Called when the line discipline is asked to poll() for data or
1503 * for special events. This code is not serialized with respect to
1504 * other events save open/close.
1506 * This code must be sure never to sleep through a hangup.
1507 * Called without the kernel lock held - fine
1509 * FIXME: if someone changes the VMIN or discipline settings for the
1510 * terminal while another process is in poll() the poll does not
1511 * recompute the new limits. Possibly set_termios should issue
1512 * a read wakeup to fix this bug.
1515 static unsigned int normal_poll(struct tty_struct * tty, struct file * file, poll_table *wait)
1517 unsigned int mask = 0;
1519 poll_wait(file, &tty->read_wait, wait);
1520 poll_wait(file, &tty->write_wait, wait);
1521 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
1522 mask |= POLLIN | POLLRDNORM;
1523 if (tty->packet && tty->link->ctrl_status)
1524 mask |= POLLPRI | POLLIN | POLLRDNORM;
1525 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
1527 if (tty_hung_up_p(file))
1529 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
1530 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
1531 tty->minimum_to_wake = MIN_CHAR(tty);
1533 tty->minimum_to_wake = 1;
1535 if (tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS &&
1536 tty->driver->write_room(tty) > 0)
1537 mask |= POLLOUT | POLLWRNORM;
1541 struct tty_ldisc tty_ldisc_N_TTY = {
1542 TTY_LDISC_MAGIC, /* magic */
1546 n_tty_open, /* open */
1547 n_tty_close, /* close */
1548 n_tty_flush_buffer, /* flush_buffer */
1549 n_tty_chars_in_buffer, /* chars_in_buffer */
1550 read_chan, /* read */
1551 write_chan, /* write */
1552 n_tty_ioctl, /* ioctl */
1553 n_tty_set_termios, /* set_termios */
1554 normal_poll, /* poll */
1556 n_tty_receive_buf, /* receive_buf */
1557 n_tty_receive_room, /* receive_room */
1558 n_tty_write_wakeup /* write_wakeup */