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 n_tty_write 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>
48 #include <linux/audit.h>
49 #include <linux/file.h>
50 #include <linux/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
66 * Special byte codes used in the echo buffer to represent operations
67 * or special handling of characters. Bytes in the echo buffer that
68 * are not part of such special blocks are treated as normal character
71 #define ECHO_OP_START 0xff
72 #define ECHO_OP_MOVE_BACK_COL 0x80
73 #define ECHO_OP_SET_CANON_COL 0x81
74 #define ECHO_OP_ERASE_TAB 0x82
76 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
77 unsigned char __user *ptr)
79 tty_audit_add_data(tty, &x, 1);
80 return put_user(x, ptr);
84 * n_tty_set__room - receive space
87 * Called by the driver to find out how much data it is
88 * permitted to feed to the line discipline without any being lost
89 * and thus to manage flow control. Not serialized. Answers for the
93 static void n_tty_set_room(struct tty_struct *tty)
95 /* tty->read_cnt is not read locked ? */
96 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
99 * If we are doing input canonicalization, and there are no
100 * pending newlines, let characters through without limit, so
101 * that erase characters will be handled. Other excess
102 * characters will be beeped.
105 left = tty->icanon && !tty->canon_data;
106 tty->receive_room = left;
109 static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
111 if (tty->read_cnt < N_TTY_BUF_SIZE) {
112 tty->read_buf[tty->read_head] = c;
113 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
119 * put_tty_queue - add character to tty
123 * Add a character to the tty read_buf queue. This is done under the
124 * read_lock to serialize character addition and also to protect us
125 * against parallel reads or flushes
128 static void put_tty_queue(unsigned char c, struct tty_struct *tty)
132 * The problem of stomping on the buffers ends here.
133 * Why didn't anyone see this one coming? --AJK
135 spin_lock_irqsave(&tty->read_lock, flags);
136 put_tty_queue_nolock(c, tty);
137 spin_unlock_irqrestore(&tty->read_lock, flags);
141 * check_unthrottle - allow new receive data
144 * Check whether to call the driver unthrottle functions
146 * Can sleep, may be called under the atomic_read_lock mutex but
147 * this is not guaranteed.
149 static void check_unthrottle(struct tty_struct *tty)
156 * reset_buffer_flags - reset buffer state
157 * @tty: terminal to reset
159 * Reset the read buffer counters, clear the flags,
160 * and make sure the driver is unthrottled. Called
161 * from n_tty_open() and n_tty_flush_buffer().
163 * Locking: tty_read_lock for read fields.
166 static void reset_buffer_flags(struct tty_struct *tty)
170 spin_lock_irqsave(&tty->read_lock, flags);
171 tty->read_head = tty->read_tail = tty->read_cnt = 0;
172 spin_unlock_irqrestore(&tty->read_lock, flags);
174 mutex_lock(&tty->echo_lock);
175 tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
176 mutex_unlock(&tty->echo_lock);
178 tty->canon_head = tty->canon_data = tty->erasing = 0;
179 memset(&tty->read_flags, 0, sizeof tty->read_flags);
181 check_unthrottle(tty);
185 * n_tty_flush_buffer - clean input queue
186 * @tty: terminal device
188 * Flush the input buffer. Called when the line discipline is
189 * being closed, when the tty layer wants the buffer flushed (eg
190 * at hangup) or when the N_TTY line discipline internally has to
191 * clean the pending queue (for example some signals).
193 * Locking: ctrl_lock, read_lock.
196 static void n_tty_flush_buffer(struct tty_struct *tty)
199 /* clear everything and unthrottle the driver */
200 reset_buffer_flags(tty);
205 spin_lock_irqsave(&tty->ctrl_lock, flags);
206 if (tty->link->packet) {
207 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
208 wake_up_interruptible(&tty->link->read_wait);
210 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
214 * n_tty_chars_in_buffer - report available bytes
217 * Report the number of characters buffered to be delivered to user
218 * at this instant in time.
223 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
228 spin_lock_irqsave(&tty->read_lock, flags);
231 } else if (tty->canon_data) {
232 n = (tty->canon_head > tty->read_tail) ?
233 tty->canon_head - tty->read_tail :
234 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
236 spin_unlock_irqrestore(&tty->read_lock, flags);
241 * is_utf8_continuation - utf8 multibyte check
244 * Returns true if the utf8 character 'c' is a multibyte continuation
245 * character. We use this to correctly compute the on screen size
246 * of the character when printing
249 static inline int is_utf8_continuation(unsigned char c)
251 return (c & 0xc0) == 0x80;
255 * is_continuation - multibyte check
258 * Returns true if the utf8 character 'c' is a multibyte continuation
259 * character and the terminal is in unicode mode.
262 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
264 return I_IUTF8(tty) && is_utf8_continuation(c);
268 * do_output_char - output one character
269 * @c: character (or partial unicode symbol)
270 * @tty: terminal device
271 * @space: space available in tty driver write buffer
273 * This is a helper function that handles one output character
274 * (including special characters like TAB, CR, LF, etc.),
275 * doing OPOST processing and putting the results in the
276 * tty driver's write buffer.
278 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
279 * and NLDLY. They simply aren't relevant in the world today.
280 * If you ever need them, add them here.
282 * Returns the number of bytes of buffer space used or -1 if
285 * Locking: should be called under the output_lock to protect
286 * the column state and space left in the buffer
289 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
303 tty->canon_column = tty->column = 0;
304 tty->ops->write(tty, "\r\n", 2);
307 tty->canon_column = tty->column;
310 if (O_ONOCR(tty) && tty->column == 0)
315 tty->canon_column = tty->column = 0;
318 tty->canon_column = tty->column = 0;
321 spaces = 8 - (tty->column & 7);
322 if (O_TABDLY(tty) == XTABS) {
325 tty->column += spaces;
326 tty->ops->write(tty, " ", spaces);
329 tty->column += spaces;
339 if (!is_continuation(c, tty))
345 tty_put_char(tty, c);
350 * process_output - output post processor
351 * @c: character (or partial unicode symbol)
352 * @tty: terminal device
354 * Output one character with OPOST processing.
355 * Returns -1 when the output device is full and the character
358 * Locking: output_lock to protect column state and space left
359 * (also, this is called from n_tty_write under the
360 * tty layer write lock)
363 static int process_output(unsigned char c, struct tty_struct *tty)
367 mutex_lock(&tty->output_lock);
369 space = tty_write_room(tty);
370 retval = do_output_char(c, tty, space);
372 mutex_unlock(&tty->output_lock);
380 * process_output_block - block post processor
381 * @tty: terminal device
382 * @buf: character buffer
383 * @nr: number of bytes to output
385 * Output a block of characters with OPOST processing.
386 * Returns the number of characters output.
388 * This path is used to speed up block console writes, among other
389 * things when processing blocks of output data. It handles only
390 * the simple cases normally found and helps to generate blocks of
391 * symbols for the console driver and thus improve performance.
393 * Locking: output_lock to protect column state and space left
394 * (also, this is called from n_tty_write under the
395 * tty layer write lock)
398 static ssize_t process_output_block(struct tty_struct *tty,
399 const unsigned char *buf, unsigned int nr)
403 const unsigned char *cp;
405 mutex_lock(&tty->output_lock);
407 space = tty_write_room(tty);
409 mutex_unlock(&tty->output_lock);
415 for (i = 0, cp = buf; i < nr; i++, cp++) {
416 unsigned char c = *cp;
424 tty->canon_column = tty->column;
427 if (O_ONOCR(tty) && tty->column == 0)
431 tty->canon_column = tty->column = 0;
443 if (!is_continuation(c, tty))
450 i = tty->ops->write(tty, buf, i);
452 mutex_unlock(&tty->output_lock);
457 * process_echoes - write pending echo characters
458 * @tty: terminal device
460 * Write previously buffered echo (and other ldisc-generated)
461 * characters to the tty.
463 * Characters generated by the ldisc (including echoes) need to
464 * be buffered because the driver's write buffer can fill during
465 * heavy program output. Echoing straight to the driver will
466 * often fail under these conditions, causing lost characters and
467 * resulting mismatches of ldisc state information.
469 * Since the ldisc state must represent the characters actually sent
470 * to the driver at the time of the write, operations like certain
471 * changes in column state are also saved in the buffer and executed
474 * A circular fifo buffer is used so that the most recent characters
475 * are prioritized. Also, when control characters are echoed with a
476 * prefixed "^", the pair is treated atomically and thus not separated.
478 * Locking: output_lock to protect column state and space left,
479 * echo_lock to protect the echo buffer
482 static void process_echoes(struct tty_struct *tty)
486 unsigned char *cp, *buf_end;
491 mutex_lock(&tty->output_lock);
492 mutex_lock(&tty->echo_lock);
494 space = tty_write_room(tty);
496 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
497 cp = tty->echo_buf + tty->echo_pos;
501 if (c == ECHO_OP_START) {
504 int no_space_left = 0;
507 * If the buffer byte is the start of a multi-byte
508 * operation, get the next byte, which is either the
509 * op code or a control character value.
513 opp -= N_TTY_BUF_SIZE;
517 unsigned int num_chars, num_bs;
519 case ECHO_OP_ERASE_TAB:
520 if (++opp == buf_end)
521 opp -= N_TTY_BUF_SIZE;
525 * Determine how many columns to go back
526 * in order to erase the tab.
527 * This depends on the number of columns
528 * used by other characters within the tab
529 * area. If this (modulo 8) count is from
530 * the start of input rather than from a
531 * previous tab, we offset by canon column.
532 * Otherwise, tab spacing is normal.
534 if (!(num_chars & 0x80))
535 num_chars += tty->canon_column;
536 num_bs = 8 - (num_chars & 7);
538 if (num_bs > space) {
544 tty_put_char(tty, '\b');
552 case ECHO_OP_SET_CANON_COL:
553 tty->canon_column = tty->column;
558 case ECHO_OP_MOVE_BACK_COL:
566 /* This is an escaped echo op start code */
571 tty_put_char(tty, ECHO_OP_START);
580 * If the op is not a special byte code,
581 * it is a ctrl char tagged to be echoed
582 * as "^X" (where X is the letter
583 * representing the control char).
584 * Note that we must ensure there is
585 * enough space for the whole ctrl pair.
592 tty_put_char(tty, '^');
593 tty_put_char(tty, op ^ 0100);
604 !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
605 int retval = do_output_char(c, tty, space);
612 tty_put_char(tty, c);
619 /* When end of circular buffer reached, wrap around */
621 cp -= N_TTY_BUF_SIZE;
627 tty->echo_overrun = 0;
629 int num_processed = tty->echo_cnt - nr;
630 tty->echo_pos += num_processed;
631 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
633 if (num_processed > 0)
634 tty->echo_overrun = 0;
637 mutex_unlock(&tty->echo_lock);
638 mutex_unlock(&tty->output_lock);
640 if (tty->ops->flush_chars)
641 tty->ops->flush_chars(tty);
645 * add_echo_byte - add a byte to the echo buffer
646 * @c: unicode byte to echo
647 * @tty: terminal device
649 * Add a character or operation byte to the echo buffer.
651 * Should be called under the echo lock to protect the echo buffer.
654 static void add_echo_byte(unsigned char c, struct tty_struct *tty)
658 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
659 /* Circular buffer is already at capacity */
660 new_byte_pos = tty->echo_pos;
663 * Since the buffer start position needs to be advanced,
664 * be sure to step by a whole operation byte group.
666 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
667 if (tty->echo_buf[(tty->echo_pos + 1) &
668 (N_TTY_BUF_SIZE - 1)] ==
679 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
681 tty->echo_overrun = 1;
683 new_byte_pos = tty->echo_pos + tty->echo_cnt;
684 new_byte_pos &= N_TTY_BUF_SIZE - 1;
688 tty->echo_buf[new_byte_pos] = c;
692 * echo_move_back_col - add operation to move back a column
693 * @tty: terminal device
695 * Add an operation to the echo buffer to move back one column.
697 * Locking: echo_lock to protect the echo buffer
700 static void echo_move_back_col(struct tty_struct *tty)
702 mutex_lock(&tty->echo_lock);
704 add_echo_byte(ECHO_OP_START, tty);
705 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
707 mutex_unlock(&tty->echo_lock);
711 * echo_set_canon_col - add operation to set the canon column
712 * @tty: terminal device
714 * Add an operation to the echo buffer to set the canon column
715 * to the current column.
717 * Locking: echo_lock to protect the echo buffer
720 static void echo_set_canon_col(struct tty_struct *tty)
722 mutex_lock(&tty->echo_lock);
724 add_echo_byte(ECHO_OP_START, tty);
725 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
727 mutex_unlock(&tty->echo_lock);
731 * echo_erase_tab - add operation to erase a tab
732 * @num_chars: number of character columns already used
733 * @after_tab: true if num_chars starts after a previous tab
734 * @tty: terminal device
736 * Add an operation to the echo buffer to erase a tab.
738 * Called by the eraser function, which knows how many character
739 * columns have been used since either a previous tab or the start
740 * of input. This information will be used later, along with
741 * canon column (if applicable), to go back the correct number
744 * Locking: echo_lock to protect the echo buffer
747 static void echo_erase_tab(unsigned int num_chars, int after_tab,
748 struct tty_struct *tty)
750 mutex_lock(&tty->echo_lock);
752 add_echo_byte(ECHO_OP_START, tty);
753 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
755 /* We only need to know this modulo 8 (tab spacing) */
758 /* Set the high bit as a flag if num_chars is after a previous tab */
762 add_echo_byte(num_chars, tty);
764 mutex_unlock(&tty->echo_lock);
768 * echo_char_raw - echo a character raw
769 * @c: unicode byte to echo
770 * @tty: terminal device
772 * Echo user input back onto the screen. This must be called only when
773 * L_ECHO(tty) is true. Called from the driver receive_buf path.
775 * This variant does not treat control characters specially.
777 * Locking: echo_lock to protect the echo buffer
780 static void echo_char_raw(unsigned char c, struct tty_struct *tty)
782 mutex_lock(&tty->echo_lock);
784 if (c == ECHO_OP_START) {
785 add_echo_byte(ECHO_OP_START, tty);
786 add_echo_byte(ECHO_OP_START, tty);
788 add_echo_byte(c, tty);
791 mutex_unlock(&tty->echo_lock);
795 * echo_char - echo a character
796 * @c: unicode byte to echo
797 * @tty: terminal device
799 * Echo user input back onto the screen. This must be called only when
800 * L_ECHO(tty) is true. Called from the driver receive_buf path.
802 * This variant tags control characters to be echoed as "^X"
803 * (where X is the letter representing the control char).
805 * Locking: echo_lock to protect the echo buffer
808 static void echo_char(unsigned char c, struct tty_struct *tty)
810 mutex_lock(&tty->echo_lock);
812 if (c == ECHO_OP_START) {
813 add_echo_byte(ECHO_OP_START, tty);
814 add_echo_byte(ECHO_OP_START, tty);
816 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
817 add_echo_byte(ECHO_OP_START, tty);
818 add_echo_byte(c, tty);
821 mutex_unlock(&tty->echo_lock);
825 * finish_erasing - complete erase
826 * @tty: tty doing the erase
829 static inline void finish_erasing(struct tty_struct *tty)
832 echo_char_raw('/', tty);
838 * eraser - handle erase function
839 * @c: character input
840 * @tty: terminal device
842 * Perform erase and necessary output when an erase character is
843 * present in the stream from the driver layer. Handles the complexities
844 * of UTF-8 multibyte symbols.
846 * Locking: read_lock for tty buffers
849 static void eraser(unsigned char c, struct tty_struct *tty)
851 enum { ERASE, WERASE, KILL } kill_type;
852 int head, seen_alnums, cnt;
855 /* FIXME: locking needed ? */
856 if (tty->read_head == tty->canon_head) {
857 /* process_output('\a', tty); */ /* what do you think? */
860 if (c == ERASE_CHAR(tty))
862 else if (c == WERASE_CHAR(tty))
866 spin_lock_irqsave(&tty->read_lock, flags);
867 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
868 (N_TTY_BUF_SIZE - 1));
869 tty->read_head = tty->canon_head;
870 spin_unlock_irqrestore(&tty->read_lock, flags);
873 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
874 spin_lock_irqsave(&tty->read_lock, flags);
875 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
876 (N_TTY_BUF_SIZE - 1));
877 tty->read_head = tty->canon_head;
878 spin_unlock_irqrestore(&tty->read_lock, flags);
880 echo_char(KILL_CHAR(tty), tty);
881 /* Add a newline if ECHOK is on and ECHOKE is off. */
883 echo_char_raw('\n', tty);
890 /* FIXME: Locking ?? */
891 while (tty->read_head != tty->canon_head) {
892 head = tty->read_head;
894 /* erase a single possibly multibyte character */
896 head = (head - 1) & (N_TTY_BUF_SIZE-1);
897 c = tty->read_buf[head];
898 } while (is_continuation(c, tty) && head != tty->canon_head);
900 /* do not partially erase */
901 if (is_continuation(c, tty))
904 if (kill_type == WERASE) {
905 /* Equivalent to BSD's ALTWERASE. */
906 if (isalnum(c) || c == '_')
908 else if (seen_alnums)
911 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
912 spin_lock_irqsave(&tty->read_lock, flags);
913 tty->read_head = head;
914 tty->read_cnt -= cnt;
915 spin_unlock_irqrestore(&tty->read_lock, flags);
917 if (L_ECHOPRT(tty)) {
919 echo_char_raw('\\', tty);
922 /* if cnt > 1, output a multi-byte character */
925 head = (head+1) & (N_TTY_BUF_SIZE-1);
926 echo_char_raw(tty->read_buf[head], tty);
927 echo_move_back_col(tty);
929 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
930 echo_char(ERASE_CHAR(tty), tty);
931 } else if (c == '\t') {
932 unsigned int num_chars = 0;
934 unsigned long tail = tty->read_head;
937 * Count the columns used for characters
938 * since the start of input or after a
940 * This info is used to go back the correct
943 while (tail != tty->canon_head) {
944 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
945 c = tty->read_buf[tail];
949 } else if (iscntrl(c)) {
952 } else if (!is_continuation(c, tty)) {
956 echo_erase_tab(num_chars, after_tab, tty);
958 if (iscntrl(c) && L_ECHOCTL(tty)) {
959 echo_char_raw('\b', tty);
960 echo_char_raw(' ', tty);
961 echo_char_raw('\b', tty);
963 if (!iscntrl(c) || L_ECHOCTL(tty)) {
964 echo_char_raw('\b', tty);
965 echo_char_raw(' ', tty);
966 echo_char_raw('\b', tty);
970 if (kill_type == ERASE)
973 if (tty->read_head == tty->canon_head && L_ECHO(tty))
978 * isig - handle the ISIG optio
981 * @flush: force flush
983 * Called when a signal is being sent due to terminal input. This
984 * may caus terminal flushing to take place according to the termios
985 * settings and character used. Called from the driver receive_buf
986 * path so serialized.
988 * Locking: ctrl_lock, read_lock (both via flush buffer)
991 static inline void isig(int sig, struct tty_struct *tty, int flush)
994 kill_pgrp(tty->pgrp, sig, 1);
995 if (flush || !L_NOFLSH(tty)) {
996 n_tty_flush_buffer(tty);
997 tty_driver_flush_buffer(tty);
1002 * n_tty_receive_break - handle break
1005 * An RS232 break event has been hit in the incoming bitstream. This
1006 * can cause a variety of events depending upon the termios settings.
1008 * Called from the receive_buf path so single threaded.
1011 static inline void n_tty_receive_break(struct tty_struct *tty)
1015 if (I_BRKINT(tty)) {
1016 isig(SIGINT, tty, 1);
1019 if (I_PARMRK(tty)) {
1020 put_tty_queue('\377', tty);
1021 put_tty_queue('\0', tty);
1023 put_tty_queue('\0', tty);
1024 wake_up_interruptible(&tty->read_wait);
1028 * n_tty_receive_overrun - handle overrun reporting
1031 * Data arrived faster than we could process it. While the tty
1032 * driver has flagged this the bits that were missed are gone
1035 * Called from the receive_buf path so single threaded. Does not
1036 * need locking as num_overrun and overrun_time are function
1040 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1045 if (time_before(tty->overrun_time, jiffies - HZ) ||
1046 time_after(tty->overrun_time, jiffies)) {
1047 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1050 tty->overrun_time = jiffies;
1051 tty->num_overrun = 0;
1056 * n_tty_receive_parity_error - error notifier
1057 * @tty: terminal device
1060 * Process a parity error and queue the right data to indicate
1061 * the error case if necessary. Locking as per n_tty_receive_buf.
1063 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1068 if (I_PARMRK(tty)) {
1069 put_tty_queue('\377', tty);
1070 put_tty_queue('\0', tty);
1071 put_tty_queue(c, tty);
1072 } else if (I_INPCK(tty))
1073 put_tty_queue('\0', tty);
1075 put_tty_queue(c, tty);
1076 wake_up_interruptible(&tty->read_wait);
1080 * n_tty_receive_char - perform processing
1081 * @tty: terminal device
1084 * Process an individual character of input received from the driver.
1085 * This is serialized with respect to itself by the rules for the
1089 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1091 unsigned long flags;
1095 put_tty_queue(c, tty);
1101 if (I_IUCLC(tty) && L_IEXTEN(tty))
1104 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1105 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1106 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1108 process_echoes(tty);
1113 if (c == START_CHAR(tty)) {
1115 process_echoes(tty);
1116 } else if (c == STOP_CHAR(tty))
1123 * If the previous character was LNEXT, or we know that this
1124 * character is not one of the characters that we'll have to
1125 * handle specially, do shortcut processing to speed things
1128 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1130 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1131 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1132 /* beep if no space */
1134 process_output('\a', tty);
1138 finish_erasing(tty);
1139 /* Record the column of first canon char. */
1140 if (tty->canon_head == tty->read_head)
1141 echo_set_canon_col(tty);
1143 process_echoes(tty);
1146 put_tty_queue(c, tty);
1147 put_tty_queue(c, tty);
1152 if (c == START_CHAR(tty)) {
1154 process_echoes(tty);
1157 if (c == STOP_CHAR(tty)) {
1166 if (c == INTR_CHAR(tty))
1169 if (c == QUIT_CHAR(tty))
1172 if (c == SUSP_CHAR(tty)) {
1175 * Note that we do not use isig() here because we want
1177 * 1) flush, 2) echo, 3) signal
1179 if (!L_NOFLSH(tty)) {
1180 n_tty_flush_buffer(tty);
1181 tty_driver_flush_buffer(tty);
1187 process_echoes(tty);
1190 kill_pgrp(tty->pgrp, signal, 1);
1200 } else if (c == '\n' && I_INLCR(tty))
1204 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1205 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1207 process_echoes(tty);
1210 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1213 finish_erasing(tty);
1214 if (L_ECHOCTL(tty)) {
1215 echo_char_raw('^', tty);
1216 echo_char_raw('\b', tty);
1217 process_echoes(tty);
1222 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1224 unsigned long tail = tty->canon_head;
1226 finish_erasing(tty);
1228 echo_char_raw('\n', tty);
1229 while (tail != tty->read_head) {
1230 echo_char(tty->read_buf[tail], tty);
1231 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1233 process_echoes(tty);
1237 if (tty->read_cnt >= N_TTY_BUF_SIZE) {
1239 process_output('\a', tty);
1242 if (L_ECHO(tty) || L_ECHONL(tty)) {
1243 echo_char_raw('\n', tty);
1244 process_echoes(tty);
1246 goto handle_newline;
1248 if (c == EOF_CHAR(tty)) {
1249 if (tty->read_cnt >= N_TTY_BUF_SIZE)
1251 if (tty->canon_head != tty->read_head)
1252 set_bit(TTY_PUSH, &tty->flags);
1253 c = __DISABLED_CHAR;
1254 goto handle_newline;
1256 if ((c == EOL_CHAR(tty)) ||
1257 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1258 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1260 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
1262 process_output('\a', tty);
1266 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1269 /* Record the column of first canon char. */
1270 if (tty->canon_head == tty->read_head)
1271 echo_set_canon_col(tty);
1273 process_echoes(tty);
1276 * XXX does PARMRK doubling happen for
1277 * EOL_CHAR and EOL2_CHAR?
1280 put_tty_queue(c, tty);
1283 spin_lock_irqsave(&tty->read_lock, flags);
1284 set_bit(tty->read_head, tty->read_flags);
1285 put_tty_queue_nolock(c, tty);
1286 tty->canon_head = tty->read_head;
1288 spin_unlock_irqrestore(&tty->read_lock, flags);
1289 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1290 if (waitqueue_active(&tty->read_wait))
1291 wake_up_interruptible(&tty->read_wait);
1296 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1297 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1298 /* beep if no space */
1300 process_output('\a', tty);
1304 finish_erasing(tty);
1306 echo_char_raw('\n', tty);
1308 /* Record the column of first canon char. */
1309 if (tty->canon_head == tty->read_head)
1310 echo_set_canon_col(tty);
1313 process_echoes(tty);
1317 put_tty_queue(c, tty);
1319 put_tty_queue(c, tty);
1324 * n_tty_write_wakeup - asynchronous I/O notifier
1327 * Required for the ptys, serial driver etc. since processes
1328 * that attach themselves to the master and rely on ASYNC
1329 * IO must be woken up
1332 static void n_tty_write_wakeup(struct tty_struct *tty)
1334 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
1335 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1339 * n_tty_receive_buf - data receive
1340 * @tty: terminal device
1343 * @count: characters
1345 * Called by the terminal driver when a block of characters has
1346 * been received. This function must be called from soft contexts
1347 * not from interrupt context. The driver is responsible for making
1348 * calls one at a time and in order (or using flush_to_ldisc)
1351 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1352 char *fp, int count)
1354 const unsigned char *p;
1355 char *f, flags = TTY_NORMAL;
1358 unsigned long cpuflags;
1363 if (tty->real_raw) {
1364 spin_lock_irqsave(&tty->read_lock, cpuflags);
1365 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1366 N_TTY_BUF_SIZE - tty->read_head);
1368 memcpy(tty->read_buf + tty->read_head, cp, i);
1369 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1374 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1375 N_TTY_BUF_SIZE - tty->read_head);
1377 memcpy(tty->read_buf + tty->read_head, cp, i);
1378 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1380 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1382 for (i = count, p = cp, f = fp; i; i--, p++) {
1387 n_tty_receive_char(tty, *p);
1390 n_tty_receive_break(tty);
1394 n_tty_receive_parity_error(tty, *p);
1397 n_tty_receive_overrun(tty);
1400 printk(KERN_ERR "%s: unknown flag %d\n",
1401 tty_name(tty, buf), flags);
1405 if (tty->ops->flush_chars)
1406 tty->ops->flush_chars(tty);
1409 n_tty_set_room(tty);
1411 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
1412 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1413 if (waitqueue_active(&tty->read_wait))
1414 wake_up_interruptible(&tty->read_wait);
1418 * Check the remaining room for the input canonicalization
1419 * mode. We don't want to throttle the driver if we're in
1420 * canonical mode and don't have a newline yet!
1422 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1426 int is_ignored(int sig)
1428 return (sigismember(¤t->blocked, sig) ||
1429 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1433 * n_tty_set_termios - termios data changed
1435 * @old: previous data
1437 * Called by the tty layer when the user changes termios flags so
1438 * that the line discipline can plan ahead. This function cannot sleep
1439 * and is protected from re-entry by the tty layer. The user is
1440 * guaranteed that this function will not be re-entered or in progress
1441 * when the ldisc is closed.
1443 * Locking: Caller holds tty->termios_mutex
1446 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1448 int canon_change = 1;
1452 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1454 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1455 tty->canon_head = tty->read_tail;
1456 tty->canon_data = 0;
1460 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1461 wake_up_interruptible(&tty->read_wait);
1463 tty->icanon = (L_ICANON(tty) != 0);
1464 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1467 n_tty_set_room(tty);
1470 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1471 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1472 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1474 memset(tty->process_char_map, 0, 256/8);
1476 if (I_IGNCR(tty) || I_ICRNL(tty))
1477 set_bit('\r', tty->process_char_map);
1479 set_bit('\n', tty->process_char_map);
1481 if (L_ICANON(tty)) {
1482 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1483 set_bit(KILL_CHAR(tty), tty->process_char_map);
1484 set_bit(EOF_CHAR(tty), tty->process_char_map);
1485 set_bit('\n', tty->process_char_map);
1486 set_bit(EOL_CHAR(tty), tty->process_char_map);
1487 if (L_IEXTEN(tty)) {
1488 set_bit(WERASE_CHAR(tty),
1489 tty->process_char_map);
1490 set_bit(LNEXT_CHAR(tty),
1491 tty->process_char_map);
1492 set_bit(EOL2_CHAR(tty),
1493 tty->process_char_map);
1495 set_bit(REPRINT_CHAR(tty),
1496 tty->process_char_map);
1500 set_bit(START_CHAR(tty), tty->process_char_map);
1501 set_bit(STOP_CHAR(tty), tty->process_char_map);
1504 set_bit(INTR_CHAR(tty), tty->process_char_map);
1505 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1506 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1508 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1513 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1514 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1515 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1520 n_tty_set_room(tty);
1521 /* The termios change make the tty ready for I/O */
1522 wake_up_interruptible(&tty->write_wait);
1523 wake_up_interruptible(&tty->read_wait);
1527 * n_tty_close - close the ldisc for this tty
1530 * Called from the terminal layer when this line discipline is
1531 * being shut down, either because of a close or becsuse of a
1532 * discipline change. The function will not be called while other
1533 * ldisc methods are in progress.
1536 static void n_tty_close(struct tty_struct *tty)
1538 n_tty_flush_buffer(tty);
1539 if (tty->read_buf) {
1540 kfree(tty->read_buf);
1541 tty->read_buf = NULL;
1543 if (tty->echo_buf) {
1544 kfree(tty->echo_buf);
1545 tty->echo_buf = NULL;
1550 * n_tty_open - open an ldisc
1551 * @tty: terminal to open
1553 * Called when this line discipline is being attached to the
1554 * terminal device. Can sleep. Called serialized so that no
1555 * other events will occur in parallel. No further open will occur
1559 static int n_tty_open(struct tty_struct *tty)
1564 /* These are ugly. Currently a malloc failure here can panic */
1565 if (!tty->read_buf) {
1566 tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1570 if (!tty->echo_buf) {
1571 tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1576 reset_buffer_flags(tty);
1578 n_tty_set_termios(tty, NULL);
1579 tty->minimum_to_wake = 1;
1584 static inline int input_available_p(struct tty_struct *tty, int amt)
1586 tty_flush_to_ldisc(tty);
1588 if (tty->canon_data)
1590 } else if (tty->read_cnt >= (amt ? amt : 1))
1597 * copy_from_read_buf - copy read data directly
1598 * @tty: terminal device
1602 * Helper function to speed up n_tty_read. It is only called when
1603 * ICANON is off; it copies characters straight from the tty queue to
1604 * user space directly. It can be profitably called twice; once to
1605 * drain the space from the tail pointer to the (physical) end of the
1606 * buffer, and once to drain the space from the (physical) beginning of
1607 * the buffer to head pointer.
1609 * Called under the tty->atomic_read_lock sem
1613 static int copy_from_read_buf(struct tty_struct *tty,
1614 unsigned char __user **b,
1620 unsigned long flags;
1623 spin_lock_irqsave(&tty->read_lock, flags);
1624 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1626 spin_unlock_irqrestore(&tty->read_lock, flags);
1628 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1630 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1631 spin_lock_irqsave(&tty->read_lock, flags);
1632 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1634 spin_unlock_irqrestore(&tty->read_lock, flags);
1641 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1645 * job_control - check job control
1647 * @file: file handle
1649 * Perform job control management checks on this file/tty descriptor
1650 * and if appropriate send any needed signals and return a negative
1651 * error code if action should be taken.
1654 * Locking: None - redirected write test is safe, testing
1655 * current->signal should possibly lock current->sighand
1659 static int job_control(struct tty_struct *tty, struct file *file)
1661 /* Job control check -- must be done at start and after
1662 every sleep (POSIX.1 7.1.1.4). */
1663 /* NOTE: not yet done after every sleep pending a thorough
1664 check of the logic of this change. -- jlc */
1665 /* don't stop on /dev/console */
1666 if (file->f_op->write != redirected_tty_write &&
1667 current->signal->tty == tty) {
1669 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1670 else if (task_pgrp(current) != tty->pgrp) {
1671 if (is_ignored(SIGTTIN) ||
1672 is_current_pgrp_orphaned())
1674 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1675 set_thread_flag(TIF_SIGPENDING);
1676 return -ERESTARTSYS;
1684 * n_tty_read - read function for tty
1686 * @file: file object
1687 * @buf: userspace buffer pointer
1690 * Perform reads for the line discipline. We are guaranteed that the
1691 * line discipline will not be closed under us but we may get multiple
1692 * parallel readers and must handle this ourselves. We may also get
1693 * a hangup. Always called in user context, may sleep.
1695 * This code must be sure never to sleep through a hangup.
1698 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1699 unsigned char __user *buf, size_t nr)
1701 unsigned char __user *b = buf;
1702 DECLARE_WAITQUEUE(wait, current);
1708 unsigned long flags;
1713 BUG_ON(!tty->read_buf);
1715 c = job_control(tty, file);
1720 timeout = MAX_SCHEDULE_TIMEOUT;
1722 time = (HZ / 10) * TIME_CHAR(tty);
1723 minimum = MIN_CHAR(tty);
1726 tty->minimum_to_wake = 1;
1727 else if (!waitqueue_active(&tty->read_wait) ||
1728 (tty->minimum_to_wake > minimum))
1729 tty->minimum_to_wake = minimum;
1736 tty->minimum_to_wake = minimum = 1;
1741 * Internal serialization of reads.
1743 if (file->f_flags & O_NONBLOCK) {
1744 if (!mutex_trylock(&tty->atomic_read_lock))
1747 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1748 return -ERESTARTSYS;
1750 packet = tty->packet;
1752 add_wait_queue(&tty->read_wait, &wait);
1754 /* First test for status change. */
1755 if (packet && tty->link->ctrl_status) {
1759 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1760 cs = tty->link->ctrl_status;
1761 tty->link->ctrl_status = 0;
1762 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1763 if (tty_put_user(tty, cs, b++)) {
1771 /* This statement must be first before checking for input
1772 so that any interrupt will set the state back to
1774 set_current_state(TASK_INTERRUPTIBLE);
1776 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1777 ((minimum - (b - buf)) >= 1))
1778 tty->minimum_to_wake = (minimum - (b - buf));
1780 if (!input_available_p(tty, 0)) {
1781 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1785 if (tty_hung_up_p(file))
1789 if (file->f_flags & O_NONBLOCK) {
1793 if (signal_pending(current)) {
1794 retval = -ERESTARTSYS;
1797 /* FIXME: does n_tty_set_room need locking ? */
1798 n_tty_set_room(tty);
1799 timeout = schedule_timeout(timeout);
1802 __set_current_state(TASK_RUNNING);
1804 /* Deal with packet mode. */
1805 if (packet && b == buf) {
1806 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1815 /* N.B. avoid overrun if nr == 0 */
1816 while (nr && tty->read_cnt) {
1819 eol = test_and_clear_bit(tty->read_tail,
1821 c = tty->read_buf[tty->read_tail];
1822 spin_lock_irqsave(&tty->read_lock, flags);
1823 tty->read_tail = ((tty->read_tail+1) &
1824 (N_TTY_BUF_SIZE-1));
1827 /* this test should be redundant:
1828 * we shouldn't be reading data if
1831 if (--tty->canon_data < 0)
1832 tty->canon_data = 0;
1834 spin_unlock_irqrestore(&tty->read_lock, flags);
1836 if (!eol || (c != __DISABLED_CHAR)) {
1837 if (tty_put_user(tty, c, b++)) {
1845 tty_audit_push(tty);
1853 /* The copy function takes the read lock and handles
1854 locking internally for this case */
1855 uncopied = copy_from_read_buf(tty, &b, &nr);
1856 uncopied += copy_from_read_buf(tty, &b, &nr);
1863 /* If there is enough space in the read buffer now, let the
1864 * low-level driver know. We use n_tty_chars_in_buffer() to
1865 * check the buffer, as it now knows about canonical mode.
1866 * Otherwise, if the driver is throttled and the line is
1867 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1868 * we won't get any more characters.
1870 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1871 n_tty_set_room(tty);
1872 check_unthrottle(tty);
1875 if (b - buf >= minimum)
1880 mutex_unlock(&tty->atomic_read_lock);
1881 remove_wait_queue(&tty->read_wait, &wait);
1883 if (!waitqueue_active(&tty->read_wait))
1884 tty->minimum_to_wake = minimum;
1886 __set_current_state(TASK_RUNNING);
1891 clear_bit(TTY_PUSH, &tty->flags);
1892 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1895 n_tty_set_room(tty);
1900 * n_tty_write - write function for tty
1902 * @file: file object
1903 * @buf: userspace buffer pointer
1906 * Write function of the terminal device. This is serialized with
1907 * respect to other write callers but not to termios changes, reads
1908 * and other such events. Since the receive code will echo characters,
1909 * thus calling driver write methods, the output_lock is used in
1910 * the output processing functions called here as well as in the
1911 * echo processing function to protect the column state and space
1912 * left in the buffer.
1914 * This code must be sure never to sleep through a hangup.
1916 * Locking: output_lock to protect column state and space left
1917 * (note that the process_output*() functions take this
1921 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1922 const unsigned char *buf, size_t nr)
1924 const unsigned char *b = buf;
1925 DECLARE_WAITQUEUE(wait, current);
1929 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1930 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1931 retval = tty_check_change(tty);
1936 /* Write out any echoed characters that are still pending */
1937 process_echoes(tty);
1939 add_wait_queue(&tty->write_wait, &wait);
1941 set_current_state(TASK_INTERRUPTIBLE);
1942 if (signal_pending(current)) {
1943 retval = -ERESTARTSYS;
1946 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1950 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1952 ssize_t num = process_output_block(tty, b, nr);
1964 if (process_output(c, tty) < 0)
1968 if (tty->ops->flush_chars)
1969 tty->ops->flush_chars(tty);
1972 c = tty->ops->write(tty, b, nr);
1985 if (file->f_flags & O_NONBLOCK) {
1992 __set_current_state(TASK_RUNNING);
1993 remove_wait_queue(&tty->write_wait, &wait);
1994 if (b - buf != nr && tty->fasync)
1995 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
1996 return (b - buf) ? b - buf : retval;
2000 * n_tty_poll - poll method for N_TTY
2001 * @tty: terminal device
2002 * @file: file accessing it
2005 * Called when the line discipline is asked to poll() for data or
2006 * for special events. This code is not serialized with respect to
2007 * other events save open/close.
2009 * This code must be sure never to sleep through a hangup.
2010 * Called without the kernel lock held - fine
2013 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2016 unsigned int mask = 0;
2018 poll_wait(file, &tty->read_wait, wait);
2019 poll_wait(file, &tty->write_wait, wait);
2020 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2021 mask |= POLLIN | POLLRDNORM;
2022 if (tty->packet && tty->link->ctrl_status)
2023 mask |= POLLPRI | POLLIN | POLLRDNORM;
2024 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2026 if (tty_hung_up_p(file))
2028 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2029 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2030 tty->minimum_to_wake = MIN_CHAR(tty);
2032 tty->minimum_to_wake = 1;
2034 if (tty->ops->write && !tty_is_writelocked(tty) &&
2035 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2036 tty_write_room(tty) > 0)
2037 mask |= POLLOUT | POLLWRNORM;
2041 static unsigned long inq_canon(struct tty_struct *tty)
2045 if (!tty->canon_data)
2047 head = tty->canon_head;
2048 tail = tty->read_tail;
2049 nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2050 /* Skip EOF-chars.. */
2051 while (head != tail) {
2052 if (test_bit(tail, tty->read_flags) &&
2053 tty->read_buf[tail] == __DISABLED_CHAR)
2055 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2060 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2061 unsigned int cmd, unsigned long arg)
2067 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2069 /* FIXME: Locking */
2070 retval = tty->read_cnt;
2072 retval = inq_canon(tty);
2073 return put_user(retval, (unsigned int __user *) arg);
2075 return n_tty_ioctl_helper(tty, file, cmd, arg);
2079 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2080 .magic = TTY_LDISC_MAGIC,
2083 .close = n_tty_close,
2084 .flush_buffer = n_tty_flush_buffer,
2085 .chars_in_buffer = n_tty_chars_in_buffer,
2087 .write = n_tty_write,
2088 .ioctl = n_tty_ioctl,
2089 .set_termios = n_tty_set_termios,
2091 .receive_buf = n_tty_receive_buf,
2092 .write_wakeup = n_tty_write_wakeup