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>
51 #include <linux/module.h>
53 #include <asm/system.h>
55 /* number of characters left in xmit buffer before select has we have room */
56 #define WAKEUP_CHARS 256
59 * This defines the low- and high-watermarks for throttling and
60 * unthrottling the TTY driver. These watermarks are used for
61 * controlling the space in the read buffer.
63 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
64 #define TTY_THRESHOLD_UNTHROTTLE 128
67 * Special byte codes used in the echo buffer to represent operations
68 * or special handling of characters. Bytes in the echo buffer that
69 * are not part of such special blocks are treated as normal character
72 #define ECHO_OP_START 0xff
73 #define ECHO_OP_MOVE_BACK_COL 0x80
74 #define ECHO_OP_SET_CANON_COL 0x81
75 #define ECHO_OP_ERASE_TAB 0x82
77 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
78 unsigned char __user *ptr)
80 tty_audit_add_data(tty, &x, 1);
81 return put_user(x, ptr);
85 * n_tty_set__room - receive space
88 * Called by the driver to find out how much data it is
89 * permitted to feed to the line discipline without any being lost
90 * and thus to manage flow control. Not serialized. Answers for the
94 static void n_tty_set_room(struct tty_struct *tty)
96 /* tty->read_cnt is not read locked ? */
97 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
101 * If we are doing input canonicalization, and there are no
102 * pending newlines, let characters through without limit, so
103 * that erase characters will be handled. Other excess
104 * characters will be beeped.
107 left = tty->icanon && !tty->canon_data;
108 old_left = tty->receive_room;
109 tty->receive_room = left;
111 /* Did this open up the receive buffer? We may need to flip */
112 if (left && !old_left)
113 schedule_work(&tty->buf.work);
116 static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
118 if (tty->read_cnt < N_TTY_BUF_SIZE) {
119 tty->read_buf[tty->read_head] = c;
120 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
126 * put_tty_queue - add character to tty
130 * Add a character to the tty read_buf queue. This is done under the
131 * read_lock to serialize character addition and also to protect us
132 * against parallel reads or flushes
135 static void put_tty_queue(unsigned char c, struct tty_struct *tty)
139 * The problem of stomping on the buffers ends here.
140 * Why didn't anyone see this one coming? --AJK
142 spin_lock_irqsave(&tty->read_lock, flags);
143 put_tty_queue_nolock(c, tty);
144 spin_unlock_irqrestore(&tty->read_lock, flags);
148 * check_unthrottle - allow new receive data
151 * Check whether to call the driver unthrottle functions
153 * Can sleep, may be called under the atomic_read_lock mutex but
154 * this is not guaranteed.
156 static void check_unthrottle(struct tty_struct *tty)
163 * reset_buffer_flags - reset buffer state
164 * @tty: terminal to reset
166 * Reset the read buffer counters, clear the flags,
167 * and make sure the driver is unthrottled. Called
168 * from n_tty_open() and n_tty_flush_buffer().
170 * Locking: tty_read_lock for read fields.
173 static void reset_buffer_flags(struct tty_struct *tty)
177 spin_lock_irqsave(&tty->read_lock, flags);
178 tty->read_head = tty->read_tail = tty->read_cnt = 0;
179 spin_unlock_irqrestore(&tty->read_lock, flags);
181 mutex_lock(&tty->echo_lock);
182 tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
183 mutex_unlock(&tty->echo_lock);
185 tty->canon_head = tty->canon_data = tty->erasing = 0;
186 memset(&tty->read_flags, 0, sizeof tty->read_flags);
191 * n_tty_flush_buffer - clean input queue
192 * @tty: terminal device
194 * Flush the input buffer. Called when the line discipline is
195 * being closed, when the tty layer wants the buffer flushed (eg
196 * at hangup) or when the N_TTY line discipline internally has to
197 * clean the pending queue (for example some signals).
199 * Locking: ctrl_lock, read_lock.
202 static void n_tty_flush_buffer(struct tty_struct *tty)
205 /* clear everything and unthrottle the driver */
206 reset_buffer_flags(tty);
211 spin_lock_irqsave(&tty->ctrl_lock, flags);
212 if (tty->link->packet) {
213 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
214 wake_up_interruptible(&tty->link->read_wait);
216 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
220 * n_tty_chars_in_buffer - report available bytes
223 * Report the number of characters buffered to be delivered to user
224 * at this instant in time.
229 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
234 spin_lock_irqsave(&tty->read_lock, flags);
237 } else if (tty->canon_data) {
238 n = (tty->canon_head > tty->read_tail) ?
239 tty->canon_head - tty->read_tail :
240 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
242 spin_unlock_irqrestore(&tty->read_lock, flags);
247 * is_utf8_continuation - utf8 multibyte check
250 * Returns true if the utf8 character 'c' is a multibyte continuation
251 * character. We use this to correctly compute the on screen size
252 * of the character when printing
255 static inline int is_utf8_continuation(unsigned char c)
257 return (c & 0xc0) == 0x80;
261 * is_continuation - multibyte check
264 * Returns true if the utf8 character 'c' is a multibyte continuation
265 * character and the terminal is in unicode mode.
268 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
270 return I_IUTF8(tty) && is_utf8_continuation(c);
274 * do_output_char - output one character
275 * @c: character (or partial unicode symbol)
276 * @tty: terminal device
277 * @space: space available in tty driver write buffer
279 * This is a helper function that handles one output character
280 * (including special characters like TAB, CR, LF, etc.),
281 * doing OPOST processing and putting the results in the
282 * tty driver's write buffer.
284 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
285 * and NLDLY. They simply aren't relevant in the world today.
286 * If you ever need them, add them here.
288 * Returns the number of bytes of buffer space used or -1 if
291 * Locking: should be called under the output_lock to protect
292 * the column state and space left in the buffer
295 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
309 tty->canon_column = tty->column = 0;
310 tty->ops->write(tty, "\r\n", 2);
313 tty->canon_column = tty->column;
316 if (O_ONOCR(tty) && tty->column == 0)
321 tty->canon_column = tty->column = 0;
324 tty->canon_column = tty->column = 0;
327 spaces = 8 - (tty->column & 7);
328 if (O_TABDLY(tty) == XTABS) {
331 tty->column += spaces;
332 tty->ops->write(tty, " ", spaces);
335 tty->column += spaces;
345 if (!is_continuation(c, tty))
351 tty_put_char(tty, c);
356 * process_output - output post processor
357 * @c: character (or partial unicode symbol)
358 * @tty: terminal device
360 * Output one character with OPOST processing.
361 * Returns -1 when the output device is full and the character
364 * Locking: output_lock to protect column state and space left
365 * (also, this is called from n_tty_write under the
366 * tty layer write lock)
369 static int process_output(unsigned char c, struct tty_struct *tty)
373 mutex_lock(&tty->output_lock);
375 space = tty_write_room(tty);
376 retval = do_output_char(c, tty, space);
378 mutex_unlock(&tty->output_lock);
386 * process_output_block - block post processor
387 * @tty: terminal device
388 * @buf: character buffer
389 * @nr: number of bytes to output
391 * Output a block of characters with OPOST processing.
392 * Returns the number of characters output.
394 * This path is used to speed up block console writes, among other
395 * things when processing blocks of output data. It handles only
396 * the simple cases normally found and helps to generate blocks of
397 * symbols for the console driver and thus improve performance.
399 * Locking: output_lock to protect column state and space left
400 * (also, this is called from n_tty_write under the
401 * tty layer write lock)
404 static ssize_t process_output_block(struct tty_struct *tty,
405 const unsigned char *buf, unsigned int nr)
409 const unsigned char *cp;
411 mutex_lock(&tty->output_lock);
413 space = tty_write_room(tty);
415 mutex_unlock(&tty->output_lock);
421 for (i = 0, cp = buf; i < nr; i++, cp++) {
422 unsigned char c = *cp;
430 tty->canon_column = tty->column;
433 if (O_ONOCR(tty) && tty->column == 0)
437 tty->canon_column = tty->column = 0;
449 if (!is_continuation(c, tty))
456 i = tty->ops->write(tty, buf, i);
458 mutex_unlock(&tty->output_lock);
463 * process_echoes - write pending echo characters
464 * @tty: terminal device
466 * Write previously buffered echo (and other ldisc-generated)
467 * characters to the tty.
469 * Characters generated by the ldisc (including echoes) need to
470 * be buffered because the driver's write buffer can fill during
471 * heavy program output. Echoing straight to the driver will
472 * often fail under these conditions, causing lost characters and
473 * resulting mismatches of ldisc state information.
475 * Since the ldisc state must represent the characters actually sent
476 * to the driver at the time of the write, operations like certain
477 * changes in column state are also saved in the buffer and executed
480 * A circular fifo buffer is used so that the most recent characters
481 * are prioritized. Also, when control characters are echoed with a
482 * prefixed "^", the pair is treated atomically and thus not separated.
484 * Locking: output_lock to protect column state and space left,
485 * echo_lock to protect the echo buffer
488 static void process_echoes(struct tty_struct *tty)
492 unsigned char *cp, *buf_end;
497 mutex_lock(&tty->output_lock);
498 mutex_lock(&tty->echo_lock);
500 space = tty_write_room(tty);
502 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
503 cp = tty->echo_buf + tty->echo_pos;
507 if (c == ECHO_OP_START) {
510 int no_space_left = 0;
513 * If the buffer byte is the start of a multi-byte
514 * operation, get the next byte, which is either the
515 * op code or a control character value.
519 opp -= N_TTY_BUF_SIZE;
523 unsigned int num_chars, num_bs;
525 case ECHO_OP_ERASE_TAB:
526 if (++opp == buf_end)
527 opp -= N_TTY_BUF_SIZE;
531 * Determine how many columns to go back
532 * in order to erase the tab.
533 * This depends on the number of columns
534 * used by other characters within the tab
535 * area. If this (modulo 8) count is from
536 * the start of input rather than from a
537 * previous tab, we offset by canon column.
538 * Otherwise, tab spacing is normal.
540 if (!(num_chars & 0x80))
541 num_chars += tty->canon_column;
542 num_bs = 8 - (num_chars & 7);
544 if (num_bs > space) {
550 tty_put_char(tty, '\b');
558 case ECHO_OP_SET_CANON_COL:
559 tty->canon_column = tty->column;
564 case ECHO_OP_MOVE_BACK_COL:
572 /* This is an escaped echo op start code */
577 tty_put_char(tty, ECHO_OP_START);
586 * If the op is not a special byte code,
587 * it is a ctrl char tagged to be echoed
588 * as "^X" (where X is the letter
589 * representing the control char).
590 * Note that we must ensure there is
591 * enough space for the whole ctrl pair.
598 tty_put_char(tty, '^');
599 tty_put_char(tty, op ^ 0100);
610 !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
611 int retval = do_output_char(c, tty, space);
618 tty_put_char(tty, c);
625 /* When end of circular buffer reached, wrap around */
627 cp -= N_TTY_BUF_SIZE;
633 tty->echo_overrun = 0;
635 int num_processed = tty->echo_cnt - nr;
636 tty->echo_pos += num_processed;
637 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
639 if (num_processed > 0)
640 tty->echo_overrun = 0;
643 mutex_unlock(&tty->echo_lock);
644 mutex_unlock(&tty->output_lock);
646 if (tty->ops->flush_chars)
647 tty->ops->flush_chars(tty);
651 * add_echo_byte - add a byte to the echo buffer
652 * @c: unicode byte to echo
653 * @tty: terminal device
655 * Add a character or operation byte to the echo buffer.
657 * Should be called under the echo lock to protect the echo buffer.
660 static void add_echo_byte(unsigned char c, struct tty_struct *tty)
664 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
665 /* Circular buffer is already at capacity */
666 new_byte_pos = tty->echo_pos;
669 * Since the buffer start position needs to be advanced,
670 * be sure to step by a whole operation byte group.
672 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
673 if (tty->echo_buf[(tty->echo_pos + 1) &
674 (N_TTY_BUF_SIZE - 1)] ==
685 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
687 tty->echo_overrun = 1;
689 new_byte_pos = tty->echo_pos + tty->echo_cnt;
690 new_byte_pos &= N_TTY_BUF_SIZE - 1;
694 tty->echo_buf[new_byte_pos] = c;
698 * echo_move_back_col - add operation to move back a column
699 * @tty: terminal device
701 * Add an operation to the echo buffer to move back one column.
703 * Locking: echo_lock to protect the echo buffer
706 static void echo_move_back_col(struct tty_struct *tty)
708 mutex_lock(&tty->echo_lock);
710 add_echo_byte(ECHO_OP_START, tty);
711 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
713 mutex_unlock(&tty->echo_lock);
717 * echo_set_canon_col - add operation to set the canon column
718 * @tty: terminal device
720 * Add an operation to the echo buffer to set the canon column
721 * to the current column.
723 * Locking: echo_lock to protect the echo buffer
726 static void echo_set_canon_col(struct tty_struct *tty)
728 mutex_lock(&tty->echo_lock);
730 add_echo_byte(ECHO_OP_START, tty);
731 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
733 mutex_unlock(&tty->echo_lock);
737 * echo_erase_tab - add operation to erase a tab
738 * @num_chars: number of character columns already used
739 * @after_tab: true if num_chars starts after a previous tab
740 * @tty: terminal device
742 * Add an operation to the echo buffer to erase a tab.
744 * Called by the eraser function, which knows how many character
745 * columns have been used since either a previous tab or the start
746 * of input. This information will be used later, along with
747 * canon column (if applicable), to go back the correct number
750 * Locking: echo_lock to protect the echo buffer
753 static void echo_erase_tab(unsigned int num_chars, int after_tab,
754 struct tty_struct *tty)
756 mutex_lock(&tty->echo_lock);
758 add_echo_byte(ECHO_OP_START, tty);
759 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
761 /* We only need to know this modulo 8 (tab spacing) */
764 /* Set the high bit as a flag if num_chars is after a previous tab */
768 add_echo_byte(num_chars, tty);
770 mutex_unlock(&tty->echo_lock);
774 * echo_char_raw - echo a character raw
775 * @c: unicode byte to echo
776 * @tty: terminal device
778 * Echo user input back onto the screen. This must be called only when
779 * L_ECHO(tty) is true. Called from the driver receive_buf path.
781 * This variant does not treat control characters specially.
783 * Locking: echo_lock to protect the echo buffer
786 static void echo_char_raw(unsigned char c, struct tty_struct *tty)
788 mutex_lock(&tty->echo_lock);
790 if (c == ECHO_OP_START) {
791 add_echo_byte(ECHO_OP_START, tty);
792 add_echo_byte(ECHO_OP_START, tty);
794 add_echo_byte(c, tty);
797 mutex_unlock(&tty->echo_lock);
801 * echo_char - echo a character
802 * @c: unicode byte to echo
803 * @tty: terminal device
805 * Echo user input back onto the screen. This must be called only when
806 * L_ECHO(tty) is true. Called from the driver receive_buf path.
808 * This variant tags control characters to be echoed as "^X"
809 * (where X is the letter representing the control char).
811 * Locking: echo_lock to protect the echo buffer
814 static void echo_char(unsigned char c, struct tty_struct *tty)
816 mutex_lock(&tty->echo_lock);
818 if (c == ECHO_OP_START) {
819 add_echo_byte(ECHO_OP_START, tty);
820 add_echo_byte(ECHO_OP_START, tty);
822 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
823 add_echo_byte(ECHO_OP_START, tty);
824 add_echo_byte(c, tty);
827 mutex_unlock(&tty->echo_lock);
831 * finish_erasing - complete erase
832 * @tty: tty doing the erase
835 static inline void finish_erasing(struct tty_struct *tty)
838 echo_char_raw('/', tty);
844 * eraser - handle erase function
845 * @c: character input
846 * @tty: terminal device
848 * Perform erase and necessary output when an erase character is
849 * present in the stream from the driver layer. Handles the complexities
850 * of UTF-8 multibyte symbols.
852 * Locking: read_lock for tty buffers
855 static void eraser(unsigned char c, struct tty_struct *tty)
857 enum { ERASE, WERASE, KILL } kill_type;
858 int head, seen_alnums, cnt;
861 /* FIXME: locking needed ? */
862 if (tty->read_head == tty->canon_head) {
863 /* process_output('\a', tty); */ /* what do you think? */
866 if (c == ERASE_CHAR(tty))
868 else if (c == WERASE_CHAR(tty))
872 spin_lock_irqsave(&tty->read_lock, flags);
873 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
874 (N_TTY_BUF_SIZE - 1));
875 tty->read_head = tty->canon_head;
876 spin_unlock_irqrestore(&tty->read_lock, flags);
879 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
880 spin_lock_irqsave(&tty->read_lock, flags);
881 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
882 (N_TTY_BUF_SIZE - 1));
883 tty->read_head = tty->canon_head;
884 spin_unlock_irqrestore(&tty->read_lock, flags);
886 echo_char(KILL_CHAR(tty), tty);
887 /* Add a newline if ECHOK is on and ECHOKE is off. */
889 echo_char_raw('\n', tty);
896 /* FIXME: Locking ?? */
897 while (tty->read_head != tty->canon_head) {
898 head = tty->read_head;
900 /* erase a single possibly multibyte character */
902 head = (head - 1) & (N_TTY_BUF_SIZE-1);
903 c = tty->read_buf[head];
904 } while (is_continuation(c, tty) && head != tty->canon_head);
906 /* do not partially erase */
907 if (is_continuation(c, tty))
910 if (kill_type == WERASE) {
911 /* Equivalent to BSD's ALTWERASE. */
912 if (isalnum(c) || c == '_')
914 else if (seen_alnums)
917 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
918 spin_lock_irqsave(&tty->read_lock, flags);
919 tty->read_head = head;
920 tty->read_cnt -= cnt;
921 spin_unlock_irqrestore(&tty->read_lock, flags);
923 if (L_ECHOPRT(tty)) {
925 echo_char_raw('\\', tty);
928 /* if cnt > 1, output a multi-byte character */
931 head = (head+1) & (N_TTY_BUF_SIZE-1);
932 echo_char_raw(tty->read_buf[head], tty);
933 echo_move_back_col(tty);
935 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
936 echo_char(ERASE_CHAR(tty), tty);
937 } else if (c == '\t') {
938 unsigned int num_chars = 0;
940 unsigned long tail = tty->read_head;
943 * Count the columns used for characters
944 * since the start of input or after a
946 * This info is used to go back the correct
949 while (tail != tty->canon_head) {
950 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
951 c = tty->read_buf[tail];
955 } else if (iscntrl(c)) {
958 } else if (!is_continuation(c, tty)) {
962 echo_erase_tab(num_chars, after_tab, tty);
964 if (iscntrl(c) && L_ECHOCTL(tty)) {
965 echo_char_raw('\b', tty);
966 echo_char_raw(' ', tty);
967 echo_char_raw('\b', tty);
969 if (!iscntrl(c) || L_ECHOCTL(tty)) {
970 echo_char_raw('\b', tty);
971 echo_char_raw(' ', tty);
972 echo_char_raw('\b', tty);
976 if (kill_type == ERASE)
979 if (tty->read_head == tty->canon_head && L_ECHO(tty))
984 * isig - handle the ISIG optio
987 * @flush: force flush
989 * Called when a signal is being sent due to terminal input. This
990 * may caus terminal flushing to take place according to the termios
991 * settings and character used. Called from the driver receive_buf
992 * path so serialized.
994 * Locking: ctrl_lock, read_lock (both via flush buffer)
997 static inline void isig(int sig, struct tty_struct *tty, int flush)
1000 kill_pgrp(tty->pgrp, sig, 1);
1001 if (flush || !L_NOFLSH(tty)) {
1002 n_tty_flush_buffer(tty);
1003 tty_driver_flush_buffer(tty);
1008 * n_tty_receive_break - handle break
1011 * An RS232 break event has been hit in the incoming bitstream. This
1012 * can cause a variety of events depending upon the termios settings.
1014 * Called from the receive_buf path so single threaded.
1017 static inline void n_tty_receive_break(struct tty_struct *tty)
1021 if (I_BRKINT(tty)) {
1022 isig(SIGINT, tty, 1);
1025 if (I_PARMRK(tty)) {
1026 put_tty_queue('\377', tty);
1027 put_tty_queue('\0', tty);
1029 put_tty_queue('\0', tty);
1030 wake_up_interruptible(&tty->read_wait);
1034 * n_tty_receive_overrun - handle overrun reporting
1037 * Data arrived faster than we could process it. While the tty
1038 * driver has flagged this the bits that were missed are gone
1041 * Called from the receive_buf path so single threaded. Does not
1042 * need locking as num_overrun and overrun_time are function
1046 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1051 if (time_before(tty->overrun_time, jiffies - HZ) ||
1052 time_after(tty->overrun_time, jiffies)) {
1053 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1056 tty->overrun_time = jiffies;
1057 tty->num_overrun = 0;
1062 * n_tty_receive_parity_error - error notifier
1063 * @tty: terminal device
1066 * Process a parity error and queue the right data to indicate
1067 * the error case if necessary. Locking as per n_tty_receive_buf.
1069 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1074 if (I_PARMRK(tty)) {
1075 put_tty_queue('\377', tty);
1076 put_tty_queue('\0', tty);
1077 put_tty_queue(c, tty);
1078 } else if (I_INPCK(tty))
1079 put_tty_queue('\0', tty);
1081 put_tty_queue(c, tty);
1082 wake_up_interruptible(&tty->read_wait);
1086 * n_tty_receive_char - perform processing
1087 * @tty: terminal device
1090 * Process an individual character of input received from the driver.
1091 * This is serialized with respect to itself by the rules for the
1095 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1097 unsigned long flags;
1101 put_tty_queue(c, tty);
1107 if (I_IUCLC(tty) && L_IEXTEN(tty))
1110 if (L_EXTPROC(tty)) {
1111 put_tty_queue(c, tty);
1115 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1116 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1117 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1119 process_echoes(tty);
1124 if (c == START_CHAR(tty)) {
1126 process_echoes(tty);
1127 } else if (c == STOP_CHAR(tty))
1134 * If the previous character was LNEXT, or we know that this
1135 * character is not one of the characters that we'll have to
1136 * handle specially, do shortcut processing to speed things
1139 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1141 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1142 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1143 /* beep if no space */
1145 process_output('\a', tty);
1149 finish_erasing(tty);
1150 /* Record the column of first canon char. */
1151 if (tty->canon_head == tty->read_head)
1152 echo_set_canon_col(tty);
1154 process_echoes(tty);
1157 put_tty_queue(c, tty);
1158 put_tty_queue(c, tty);
1163 if (c == START_CHAR(tty)) {
1165 process_echoes(tty);
1168 if (c == STOP_CHAR(tty)) {
1177 if (c == INTR_CHAR(tty))
1180 if (c == QUIT_CHAR(tty))
1183 if (c == SUSP_CHAR(tty)) {
1186 * Note that we do not use isig() here because we want
1188 * 1) flush, 2) echo, 3) signal
1190 if (!L_NOFLSH(tty)) {
1191 n_tty_flush_buffer(tty);
1192 tty_driver_flush_buffer(tty);
1198 process_echoes(tty);
1201 kill_pgrp(tty->pgrp, signal, 1);
1211 } else if (c == '\n' && I_INLCR(tty))
1215 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1216 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1218 process_echoes(tty);
1221 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1224 finish_erasing(tty);
1225 if (L_ECHOCTL(tty)) {
1226 echo_char_raw('^', tty);
1227 echo_char_raw('\b', tty);
1228 process_echoes(tty);
1233 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1235 unsigned long tail = tty->canon_head;
1237 finish_erasing(tty);
1239 echo_char_raw('\n', tty);
1240 while (tail != tty->read_head) {
1241 echo_char(tty->read_buf[tail], tty);
1242 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1244 process_echoes(tty);
1248 if (tty->read_cnt >= N_TTY_BUF_SIZE) {
1250 process_output('\a', tty);
1253 if (L_ECHO(tty) || L_ECHONL(tty)) {
1254 echo_char_raw('\n', tty);
1255 process_echoes(tty);
1257 goto handle_newline;
1259 if (c == EOF_CHAR(tty)) {
1260 if (tty->read_cnt >= N_TTY_BUF_SIZE)
1262 if (tty->canon_head != tty->read_head)
1263 set_bit(TTY_PUSH, &tty->flags);
1264 c = __DISABLED_CHAR;
1265 goto handle_newline;
1267 if ((c == EOL_CHAR(tty)) ||
1268 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1269 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1271 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
1273 process_output('\a', tty);
1277 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1280 /* Record the column of first canon char. */
1281 if (tty->canon_head == tty->read_head)
1282 echo_set_canon_col(tty);
1284 process_echoes(tty);
1287 * XXX does PARMRK doubling happen for
1288 * EOL_CHAR and EOL2_CHAR?
1291 put_tty_queue(c, tty);
1294 spin_lock_irqsave(&tty->read_lock, flags);
1295 set_bit(tty->read_head, tty->read_flags);
1296 put_tty_queue_nolock(c, tty);
1297 tty->canon_head = tty->read_head;
1299 spin_unlock_irqrestore(&tty->read_lock, flags);
1300 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1301 if (waitqueue_active(&tty->read_wait))
1302 wake_up_interruptible(&tty->read_wait);
1307 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1308 if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1309 /* beep if no space */
1311 process_output('\a', tty);
1315 finish_erasing(tty);
1317 echo_char_raw('\n', tty);
1319 /* Record the column of first canon char. */
1320 if (tty->canon_head == tty->read_head)
1321 echo_set_canon_col(tty);
1324 process_echoes(tty);
1328 put_tty_queue(c, tty);
1330 put_tty_queue(c, tty);
1335 * n_tty_write_wakeup - asynchronous I/O notifier
1338 * Required for the ptys, serial driver etc. since processes
1339 * that attach themselves to the master and rely on ASYNC
1340 * IO must be woken up
1343 static void n_tty_write_wakeup(struct tty_struct *tty)
1345 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
1346 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1350 * n_tty_receive_buf - data receive
1351 * @tty: terminal device
1354 * @count: characters
1356 * Called by the terminal driver when a block of characters has
1357 * been received. This function must be called from soft contexts
1358 * not from interrupt context. The driver is responsible for making
1359 * calls one at a time and in order (or using flush_to_ldisc)
1362 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1363 char *fp, int count)
1365 const unsigned char *p;
1366 char *f, flags = TTY_NORMAL;
1369 unsigned long cpuflags;
1374 if (tty->real_raw) {
1375 spin_lock_irqsave(&tty->read_lock, cpuflags);
1376 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1377 N_TTY_BUF_SIZE - tty->read_head);
1379 memcpy(tty->read_buf + tty->read_head, cp, i);
1380 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1385 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1386 N_TTY_BUF_SIZE - tty->read_head);
1388 memcpy(tty->read_buf + tty->read_head, cp, i);
1389 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1391 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1393 for (i = count, p = cp, f = fp; i; i--, p++) {
1398 n_tty_receive_char(tty, *p);
1401 n_tty_receive_break(tty);
1405 n_tty_receive_parity_error(tty, *p);
1408 n_tty_receive_overrun(tty);
1411 printk(KERN_ERR "%s: unknown flag %d\n",
1412 tty_name(tty, buf), flags);
1416 if (tty->ops->flush_chars)
1417 tty->ops->flush_chars(tty);
1420 n_tty_set_room(tty);
1422 if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
1424 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1425 if (waitqueue_active(&tty->read_wait))
1426 wake_up_interruptible(&tty->read_wait);
1430 * Check the remaining room for the input canonicalization
1431 * mode. We don't want to throttle the driver if we're in
1432 * canonical mode and don't have a newline yet!
1434 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1438 int is_ignored(int sig)
1440 return (sigismember(¤t->blocked, sig) ||
1441 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1445 * n_tty_set_termios - termios data changed
1447 * @old: previous data
1449 * Called by the tty layer when the user changes termios flags so
1450 * that the line discipline can plan ahead. This function cannot sleep
1451 * and is protected from re-entry by the tty layer. The user is
1452 * guaranteed that this function will not be re-entered or in progress
1453 * when the ldisc is closed.
1455 * Locking: Caller holds tty->termios_mutex
1458 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1460 int canon_change = 1;
1464 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1466 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1467 tty->canon_head = tty->read_tail;
1468 tty->canon_data = 0;
1472 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1473 wake_up_interruptible(&tty->read_wait);
1475 tty->icanon = (L_ICANON(tty) != 0);
1476 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1479 n_tty_set_room(tty);
1482 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1483 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1484 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1486 memset(tty->process_char_map, 0, 256/8);
1488 if (I_IGNCR(tty) || I_ICRNL(tty))
1489 set_bit('\r', tty->process_char_map);
1491 set_bit('\n', tty->process_char_map);
1493 if (L_ICANON(tty)) {
1494 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1495 set_bit(KILL_CHAR(tty), tty->process_char_map);
1496 set_bit(EOF_CHAR(tty), tty->process_char_map);
1497 set_bit('\n', tty->process_char_map);
1498 set_bit(EOL_CHAR(tty), tty->process_char_map);
1499 if (L_IEXTEN(tty)) {
1500 set_bit(WERASE_CHAR(tty),
1501 tty->process_char_map);
1502 set_bit(LNEXT_CHAR(tty),
1503 tty->process_char_map);
1504 set_bit(EOL2_CHAR(tty),
1505 tty->process_char_map);
1507 set_bit(REPRINT_CHAR(tty),
1508 tty->process_char_map);
1512 set_bit(START_CHAR(tty), tty->process_char_map);
1513 set_bit(STOP_CHAR(tty), tty->process_char_map);
1516 set_bit(INTR_CHAR(tty), tty->process_char_map);
1517 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1518 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1520 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1525 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1526 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1527 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1532 n_tty_set_room(tty);
1533 /* The termios change make the tty ready for I/O */
1534 wake_up_interruptible(&tty->write_wait);
1535 wake_up_interruptible(&tty->read_wait);
1539 * n_tty_close - close the ldisc for this tty
1542 * Called from the terminal layer when this line discipline is
1543 * being shut down, either because of a close or becsuse of a
1544 * discipline change. The function will not be called while other
1545 * ldisc methods are in progress.
1548 static void n_tty_close(struct tty_struct *tty)
1550 n_tty_flush_buffer(tty);
1551 if (tty->read_buf) {
1552 kfree(tty->read_buf);
1553 tty->read_buf = NULL;
1555 if (tty->echo_buf) {
1556 kfree(tty->echo_buf);
1557 tty->echo_buf = NULL;
1562 * n_tty_open - open an ldisc
1563 * @tty: terminal to open
1565 * Called when this line discipline is being attached to the
1566 * terminal device. Can sleep. Called serialized so that no
1567 * other events will occur in parallel. No further open will occur
1571 static int n_tty_open(struct tty_struct *tty)
1576 /* These are ugly. Currently a malloc failure here can panic */
1577 if (!tty->read_buf) {
1578 tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1582 if (!tty->echo_buf) {
1583 tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1588 reset_buffer_flags(tty);
1589 tty_unthrottle(tty);
1591 n_tty_set_termios(tty, NULL);
1592 tty->minimum_to_wake = 1;
1597 static inline int input_available_p(struct tty_struct *tty, int amt)
1599 tty_flush_to_ldisc(tty);
1600 if (tty->icanon && !L_EXTPROC(tty)) {
1601 if (tty->canon_data)
1603 } else if (tty->read_cnt >= (amt ? amt : 1))
1610 * copy_from_read_buf - copy read data directly
1611 * @tty: terminal device
1615 * Helper function to speed up n_tty_read. It is only called when
1616 * ICANON is off; it copies characters straight from the tty queue to
1617 * user space directly. It can be profitably called twice; once to
1618 * drain the space from the tail pointer to the (physical) end of the
1619 * buffer, and once to drain the space from the (physical) beginning of
1620 * the buffer to head pointer.
1622 * Called under the tty->atomic_read_lock sem
1626 static int copy_from_read_buf(struct tty_struct *tty,
1627 unsigned char __user **b,
1633 unsigned long flags;
1636 spin_lock_irqsave(&tty->read_lock, flags);
1637 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1639 spin_unlock_irqrestore(&tty->read_lock, flags);
1641 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1643 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1644 spin_lock_irqsave(&tty->read_lock, flags);
1645 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1647 /* Turn single EOF into zero-length read */
1648 if (L_EXTPROC(tty) && tty->icanon && n == 1) {
1649 if (!tty->read_cnt && (*b)[n-1] == EOF_CHAR(tty))
1652 spin_unlock_irqrestore(&tty->read_lock, flags);
1659 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1663 * job_control - check job control
1665 * @file: file handle
1667 * Perform job control management checks on this file/tty descriptor
1668 * and if appropriate send any needed signals and return a negative
1669 * error code if action should be taken.
1672 * Locking: None - redirected write test is safe, testing
1673 * current->signal should possibly lock current->sighand
1677 static int job_control(struct tty_struct *tty, struct file *file)
1679 /* Job control check -- must be done at start and after
1680 every sleep (POSIX.1 7.1.1.4). */
1681 /* NOTE: not yet done after every sleep pending a thorough
1682 check of the logic of this change. -- jlc */
1683 /* don't stop on /dev/console */
1684 if (file->f_op->write != redirected_tty_write &&
1685 current->signal->tty == tty) {
1687 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1688 else if (task_pgrp(current) != tty->pgrp) {
1689 if (is_ignored(SIGTTIN) ||
1690 is_current_pgrp_orphaned())
1692 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1693 set_thread_flag(TIF_SIGPENDING);
1694 return -ERESTARTSYS;
1702 * n_tty_read - read function for tty
1704 * @file: file object
1705 * @buf: userspace buffer pointer
1708 * Perform reads for the line discipline. We are guaranteed that the
1709 * line discipline will not be closed under us but we may get multiple
1710 * parallel readers and must handle this ourselves. We may also get
1711 * a hangup. Always called in user context, may sleep.
1713 * This code must be sure never to sleep through a hangup.
1716 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1717 unsigned char __user *buf, size_t nr)
1719 unsigned char __user *b = buf;
1720 DECLARE_WAITQUEUE(wait, current);
1726 unsigned long flags;
1731 BUG_ON(!tty->read_buf);
1733 c = job_control(tty, file);
1738 timeout = MAX_SCHEDULE_TIMEOUT;
1740 time = (HZ / 10) * TIME_CHAR(tty);
1741 minimum = MIN_CHAR(tty);
1744 tty->minimum_to_wake = 1;
1745 else if (!waitqueue_active(&tty->read_wait) ||
1746 (tty->minimum_to_wake > minimum))
1747 tty->minimum_to_wake = minimum;
1754 tty->minimum_to_wake = minimum = 1;
1759 * Internal serialization of reads.
1761 if (file->f_flags & O_NONBLOCK) {
1762 if (!mutex_trylock(&tty->atomic_read_lock))
1765 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1766 return -ERESTARTSYS;
1768 packet = tty->packet;
1770 add_wait_queue(&tty->read_wait, &wait);
1772 /* First test for status change. */
1773 if (packet && tty->link->ctrl_status) {
1777 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1778 cs = tty->link->ctrl_status;
1779 tty->link->ctrl_status = 0;
1780 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1781 if (tty_put_user(tty, cs, b++)) {
1789 /* This statement must be first before checking for input
1790 so that any interrupt will set the state back to
1792 set_current_state(TASK_INTERRUPTIBLE);
1794 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1795 ((minimum - (b - buf)) >= 1))
1796 tty->minimum_to_wake = (minimum - (b - buf));
1798 if (!input_available_p(tty, 0)) {
1799 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1803 if (tty_hung_up_p(file))
1807 if (file->f_flags & O_NONBLOCK) {
1811 if (signal_pending(current)) {
1812 retval = -ERESTARTSYS;
1815 /* FIXME: does n_tty_set_room need locking ? */
1816 n_tty_set_room(tty);
1817 timeout = schedule_timeout(timeout);
1818 BUG_ON(!tty->read_buf);
1821 __set_current_state(TASK_RUNNING);
1823 /* Deal with packet mode. */
1824 if (packet && b == buf) {
1825 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1833 if (tty->icanon && !L_EXTPROC(tty)) {
1834 /* N.B. avoid overrun if nr == 0 */
1835 while (nr && tty->read_cnt) {
1838 eol = test_and_clear_bit(tty->read_tail,
1840 c = tty->read_buf[tty->read_tail];
1841 spin_lock_irqsave(&tty->read_lock, flags);
1842 tty->read_tail = ((tty->read_tail+1) &
1843 (N_TTY_BUF_SIZE-1));
1846 /* this test should be redundant:
1847 * we shouldn't be reading data if
1850 if (--tty->canon_data < 0)
1851 tty->canon_data = 0;
1853 spin_unlock_irqrestore(&tty->read_lock, flags);
1855 if (!eol || (c != __DISABLED_CHAR)) {
1856 if (tty_put_user(tty, c, b++)) {
1864 tty_audit_push(tty);
1872 /* The copy function takes the read lock and handles
1873 locking internally for this case */
1874 uncopied = copy_from_read_buf(tty, &b, &nr);
1875 uncopied += copy_from_read_buf(tty, &b, &nr);
1882 /* If there is enough space in the read buffer now, let the
1883 * low-level driver know. We use n_tty_chars_in_buffer() to
1884 * check the buffer, as it now knows about canonical mode.
1885 * Otherwise, if the driver is throttled and the line is
1886 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1887 * we won't get any more characters.
1889 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1890 n_tty_set_room(tty);
1891 check_unthrottle(tty);
1894 if (b - buf >= minimum)
1899 mutex_unlock(&tty->atomic_read_lock);
1900 remove_wait_queue(&tty->read_wait, &wait);
1902 if (!waitqueue_active(&tty->read_wait))
1903 tty->minimum_to_wake = minimum;
1905 __set_current_state(TASK_RUNNING);
1910 clear_bit(TTY_PUSH, &tty->flags);
1911 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1914 n_tty_set_room(tty);
1919 * n_tty_write - write function for tty
1921 * @file: file object
1922 * @buf: userspace buffer pointer
1925 * Write function of the terminal device. This is serialized with
1926 * respect to other write callers but not to termios changes, reads
1927 * and other such events. Since the receive code will echo characters,
1928 * thus calling driver write methods, the output_lock is used in
1929 * the output processing functions called here as well as in the
1930 * echo processing function to protect the column state and space
1931 * left in the buffer.
1933 * This code must be sure never to sleep through a hangup.
1935 * Locking: output_lock to protect column state and space left
1936 * (note that the process_output*() functions take this
1940 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1941 const unsigned char *buf, size_t nr)
1943 const unsigned char *b = buf;
1944 DECLARE_WAITQUEUE(wait, current);
1948 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1949 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1950 retval = tty_check_change(tty);
1955 /* Write out any echoed characters that are still pending */
1956 process_echoes(tty);
1958 add_wait_queue(&tty->write_wait, &wait);
1960 set_current_state(TASK_INTERRUPTIBLE);
1961 if (signal_pending(current)) {
1962 retval = -ERESTARTSYS;
1965 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1969 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1971 ssize_t num = process_output_block(tty, b, nr);
1983 if (process_output(c, tty) < 0)
1987 if (tty->ops->flush_chars)
1988 tty->ops->flush_chars(tty);
1991 c = tty->ops->write(tty, b, nr);
2004 if (file->f_flags & O_NONBLOCK) {
2011 __set_current_state(TASK_RUNNING);
2012 remove_wait_queue(&tty->write_wait, &wait);
2013 if (b - buf != nr && tty->fasync)
2014 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2015 return (b - buf) ? b - buf : retval;
2019 * n_tty_poll - poll method for N_TTY
2020 * @tty: terminal device
2021 * @file: file accessing it
2024 * Called when the line discipline is asked to poll() for data or
2025 * for special events. This code is not serialized with respect to
2026 * other events save open/close.
2028 * This code must be sure never to sleep through a hangup.
2029 * Called without the kernel lock held - fine
2032 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2035 unsigned int mask = 0;
2037 poll_wait(file, &tty->read_wait, wait);
2038 poll_wait(file, &tty->write_wait, wait);
2039 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2040 mask |= POLLIN | POLLRDNORM;
2041 if (tty->packet && tty->link->ctrl_status)
2042 mask |= POLLPRI | POLLIN | POLLRDNORM;
2043 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2045 if (tty_hung_up_p(file))
2047 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2048 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2049 tty->minimum_to_wake = MIN_CHAR(tty);
2051 tty->minimum_to_wake = 1;
2053 if (tty->ops->write && !tty_is_writelocked(tty) &&
2054 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2055 tty_write_room(tty) > 0)
2056 mask |= POLLOUT | POLLWRNORM;
2060 static unsigned long inq_canon(struct tty_struct *tty)
2064 if (!tty->canon_data)
2066 head = tty->canon_head;
2067 tail = tty->read_tail;
2068 nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2069 /* Skip EOF-chars.. */
2070 while (head != tail) {
2071 if (test_bit(tail, tty->read_flags) &&
2072 tty->read_buf[tail] == __DISABLED_CHAR)
2074 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2079 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2080 unsigned int cmd, unsigned long arg)
2086 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2088 /* FIXME: Locking */
2089 retval = tty->read_cnt;
2091 retval = inq_canon(tty);
2092 return put_user(retval, (unsigned int __user *) arg);
2094 return n_tty_ioctl_helper(tty, file, cmd, arg);
2098 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2099 .magic = TTY_LDISC_MAGIC,
2102 .close = n_tty_close,
2103 .flush_buffer = n_tty_flush_buffer,
2104 .chars_in_buffer = n_tty_chars_in_buffer,
2106 .write = n_tty_write,
2107 .ioctl = n_tty_ioctl,
2108 .set_termios = n_tty_set_termios,
2110 .receive_buf = n_tty_receive_buf,
2111 .write_wakeup = n_tty_write_wakeup
2115 * n_tty_inherit_ops - inherit N_TTY methods
2116 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2118 * Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
2122 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2124 *ops = tty_ldisc_N_TTY;
2126 ops->refcount = ops->flags = 0;
2128 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);