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 unsigned char *alloc_buf(void)
78 gfp_t prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
80 if (PAGE_SIZE != N_TTY_BUF_SIZE)
81 return kmalloc(N_TTY_BUF_SIZE, prio);
83 return (unsigned char *)__get_free_page(prio);
86 static inline void free_buf(unsigned char *buf)
88 if (PAGE_SIZE != N_TTY_BUF_SIZE)
91 free_page((unsigned long) buf);
94 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
95 unsigned char __user *ptr)
97 tty_audit_add_data(tty, &x, 1);
98 return put_user(x, ptr);
102 * n_tty_set__room - receive space
105 * Called by the driver to find out how much data it is
106 * permitted to feed to the line discipline without any being lost
107 * and thus to manage flow control. Not serialized. Answers for the
111 static void n_tty_set_room(struct tty_struct *tty)
113 /* tty->read_cnt is not read locked ? */
114 int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
117 * If we are doing input canonicalization, and there are no
118 * pending newlines, let characters through without limit, so
119 * that erase characters will be handled. Other excess
120 * characters will be beeped.
123 left = tty->icanon && !tty->canon_data;
124 tty->receive_room = left;
127 static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
129 if (tty->read_cnt < N_TTY_BUF_SIZE) {
130 tty->read_buf[tty->read_head] = c;
131 tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
137 * put_tty_queue - add character to tty
141 * Add a character to the tty read_buf queue. This is done under the
142 * read_lock to serialize character addition and also to protect us
143 * against parallel reads or flushes
146 static void put_tty_queue(unsigned char c, struct tty_struct *tty)
150 * The problem of stomping on the buffers ends here.
151 * Why didn't anyone see this one coming? --AJK
153 spin_lock_irqsave(&tty->read_lock, flags);
154 put_tty_queue_nolock(c, tty);
155 spin_unlock_irqrestore(&tty->read_lock, flags);
159 * check_unthrottle - allow new receive data
162 * Check whether to call the driver unthrottle functions
164 * Can sleep, may be called under the atomic_read_lock mutex but
165 * this is not guaranteed.
167 static void check_unthrottle(struct tty_struct *tty)
174 * reset_buffer_flags - reset buffer state
175 * @tty: terminal to reset
177 * Reset the read buffer counters, clear the flags,
178 * and make sure the driver is unthrottled. Called
179 * from n_tty_open() and n_tty_flush_buffer().
181 * Locking: tty_read_lock for read fields.
184 static void reset_buffer_flags(struct tty_struct *tty)
188 spin_lock_irqsave(&tty->read_lock, flags);
189 tty->read_head = tty->read_tail = tty->read_cnt = 0;
190 spin_unlock_irqrestore(&tty->read_lock, flags);
192 mutex_lock(&tty->echo_lock);
193 tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
194 mutex_unlock(&tty->echo_lock);
196 tty->canon_head = tty->canon_data = tty->erasing = 0;
197 memset(&tty->read_flags, 0, sizeof tty->read_flags);
199 check_unthrottle(tty);
203 * n_tty_flush_buffer - clean input queue
204 * @tty: terminal device
206 * Flush the input buffer. Called when the line discipline is
207 * being closed, when the tty layer wants the buffer flushed (eg
208 * at hangup) or when the N_TTY line discipline internally has to
209 * clean the pending queue (for example some signals).
211 * Locking: ctrl_lock, read_lock.
214 static void n_tty_flush_buffer(struct tty_struct *tty)
217 /* clear everything and unthrottle the driver */
218 reset_buffer_flags(tty);
223 spin_lock_irqsave(&tty->ctrl_lock, flags);
224 if (tty->link->packet) {
225 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
226 wake_up_interruptible(&tty->link->read_wait);
228 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
232 * n_tty_chars_in_buffer - report available bytes
235 * Report the number of characters buffered to be delivered to user
236 * at this instant in time.
241 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
246 spin_lock_irqsave(&tty->read_lock, flags);
249 } else if (tty->canon_data) {
250 n = (tty->canon_head > tty->read_tail) ?
251 tty->canon_head - tty->read_tail :
252 tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
254 spin_unlock_irqrestore(&tty->read_lock, flags);
259 * is_utf8_continuation - utf8 multibyte check
262 * Returns true if the utf8 character 'c' is a multibyte continuation
263 * character. We use this to correctly compute the on screen size
264 * of the character when printing
267 static inline int is_utf8_continuation(unsigned char c)
269 return (c & 0xc0) == 0x80;
273 * is_continuation - multibyte check
276 * Returns true if the utf8 character 'c' is a multibyte continuation
277 * character and the terminal is in unicode mode.
280 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
282 return I_IUTF8(tty) && is_utf8_continuation(c);
286 * do_output_char - output one character
287 * @c: character (or partial unicode symbol)
288 * @tty: terminal device
289 * @space: space available in tty driver write buffer
291 * This is a helper function that handles one output character
292 * (including special characters like TAB, CR, LF, etc.),
293 * putting the results in the tty driver's write buffer.
295 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
296 * and NLDLY. They simply aren't relevant in the world today.
297 * If you ever need them, add them here.
299 * Returns the number of bytes of buffer space used or -1 if
302 * Locking: should be called under the output_lock to protect
303 * the column state and space left in the buffer
306 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
320 tty->canon_column = tty->column = 0;
321 tty_put_char(tty, '\r');
322 tty_put_char(tty, c);
325 tty->canon_column = tty->column;
328 if (O_ONOCR(tty) && tty->column == 0)
333 tty->canon_column = tty->column = 0;
336 tty->canon_column = tty->column = 0;
339 spaces = 8 - (tty->column & 7);
340 if (O_TABDLY(tty) == XTABS) {
343 tty->column += spaces;
344 tty->ops->write(tty, " ", spaces);
347 tty->column += spaces;
356 if (!iscntrl(c) && !is_continuation(c, tty))
361 tty_put_char(tty, c);
366 * process_output - output post processor
367 * @c: character (or partial unicode symbol)
368 * @tty: terminal device
370 * Perform OPOST processing. Returns -1 when the output device is
371 * full and the character must be retried.
373 * Locking: output_lock to protect column state and space left
374 * (also, this is called from n_tty_write under the
375 * tty layer write lock)
378 static int process_output(unsigned char c, struct tty_struct *tty)
382 mutex_lock(&tty->output_lock);
384 space = tty_write_room(tty);
385 retval = do_output_char(c, tty, space);
387 mutex_unlock(&tty->output_lock);
395 * process_output_block - block post processor
396 * @tty: terminal device
397 * @inbuf: user buffer
398 * @nr: number of bytes
400 * This path is used to speed up block console writes, among other
401 * things when processing blocks of output data. It handles only
402 * the simple cases normally found and helps to generate blocks of
403 * symbols for the console driver and thus improve performance.
405 * Locking: output_lock to protect column state and space left
406 * (also, this is called from n_tty_write under the
407 * tty layer write lock)
410 static ssize_t process_output_block(struct tty_struct *tty,
411 const unsigned char *buf, unsigned int nr)
415 const unsigned char *cp;
417 mutex_lock(&tty->output_lock);
419 space = tty_write_room(tty);
421 mutex_unlock(&tty->output_lock);
427 for (i = 0, cp = buf; i < nr; i++, cp++) {
434 tty->canon_column = tty->column;
437 if (O_ONOCR(tty) && tty->column == 0)
441 tty->canon_column = tty->column = 0;
458 i = tty->ops->write(tty, buf, i);
460 mutex_unlock(&tty->output_lock);
465 * process_echoes - write pending echo characters
466 * @tty: terminal device
468 * Write previously buffered echo (and other ldisc-generated)
469 * characters to the tty.
471 * Characters generated by the ldisc (including echoes) need to
472 * be buffered because the driver's write buffer can fill during
473 * heavy program output. Echoing straight to the driver will
474 * often fail under these conditions, causing lost characters and
475 * resulting mismatches of ldisc state information.
477 * Since the ldisc state must represent the characters actually sent
478 * to the driver at the time of the write, operations like certain
479 * changes in column state are also saved in the buffer and executed
482 * A circular fifo buffer is used so that the most recent characters
483 * are prioritized. Also, when control characters are echoed with a
484 * prefixed "^", the pair is treated atomically and thus not separated.
486 * Locking: output_lock to protect column state and space left,
487 * echo_lock to protect the echo buffer
490 static void process_echoes(struct tty_struct *tty)
494 unsigned char *cp, *buf_end;
499 mutex_lock(&tty->output_lock);
500 mutex_lock(&tty->echo_lock);
502 space = tty_write_room(tty);
504 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
505 cp = tty->echo_buf + tty->echo_pos;
509 if (c == ECHO_OP_START) {
512 int no_space_left = 0;
515 * If the buffer byte is the start of a multi-byte
516 * operation, get the next byte, which is either the
517 * op code or a control character value.
521 opp -= N_TTY_BUF_SIZE;
525 unsigned int num_chars, num_bs;
527 case ECHO_OP_ERASE_TAB:
528 if (++opp == buf_end)
529 opp -= N_TTY_BUF_SIZE;
533 * Determine how many columns to go back
534 * in order to erase the tab.
535 * This depends on the number of columns
536 * used by other characters within the tab
537 * area. If this (modulo 8) count is from
538 * the start of input rather than from a
539 * previous tab, we offset by canon column.
540 * Otherwise, tab spacing is normal.
542 if (!(num_chars & 0x80))
543 num_chars += tty->canon_column;
544 num_bs = 8 - (num_chars & 7);
546 if (num_bs > space) {
552 tty_put_char(tty, '\b');
560 case ECHO_OP_SET_CANON_COL:
561 tty->canon_column = tty->column;
566 case ECHO_OP_MOVE_BACK_COL:
574 /* This is an escaped echo op start code */
579 tty_put_char(tty, ECHO_OP_START);
588 if (L_ECHOCTL(tty)) {
590 * Ensure there is enough space
591 * for the whole ctrl pair.
597 tty_put_char(tty, '^');
598 tty_put_char(tty, op ^ 0100);
606 tty_put_char(tty, op);
611 * If above falls through, this was an
623 retval = do_output_char(c, tty, space);
631 /* When end of circular buffer reached, wrap around */
633 cp -= N_TTY_BUF_SIZE;
639 tty->echo_overrun = 0;
641 int num_processed = tty->echo_cnt - nr;
642 tty->echo_pos += num_processed;
643 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
645 if (num_processed > 0)
646 tty->echo_overrun = 0;
649 mutex_unlock(&tty->echo_lock);
650 mutex_unlock(&tty->output_lock);
652 if (tty->ops->flush_chars)
653 tty->ops->flush_chars(tty);
657 * add_echo_byte - add a byte to the echo buffer
658 * @c: unicode byte to echo
659 * @tty: terminal device
661 * Add a character or operation byte to the echo buffer.
663 * Should be called under the echo lock to protect the echo buffer.
666 static void add_echo_byte(unsigned char c, struct tty_struct *tty)
670 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
671 /* Circular buffer is already at capacity */
672 new_byte_pos = tty->echo_pos;
675 * Since the buffer start position needs to be advanced,
676 * be sure to step by a whole operation byte group.
678 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
679 if (tty->echo_buf[(tty->echo_pos + 1) &
680 (N_TTY_BUF_SIZE - 1)] ==
691 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
693 tty->echo_overrun = 1;
695 new_byte_pos = tty->echo_pos + tty->echo_cnt;
696 new_byte_pos &= N_TTY_BUF_SIZE - 1;
700 tty->echo_buf[new_byte_pos] = c;
704 * echo_move_back_col - add operation to move back a column
705 * @tty: terminal device
707 * Add an operation to the echo buffer to move back one column.
709 * Locking: echo_lock to protect the echo buffer
712 static void echo_move_back_col(struct tty_struct *tty)
714 mutex_lock(&tty->echo_lock);
716 add_echo_byte(ECHO_OP_START, tty);
717 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
719 mutex_unlock(&tty->echo_lock);
723 * echo_set_canon_col - add operation to set the canon column
724 * @tty: terminal device
726 * Add an operation to the echo buffer to set the canon column
727 * to the current column.
729 * Locking: echo_lock to protect the echo buffer
732 static void echo_set_canon_col(struct tty_struct *tty)
734 mutex_lock(&tty->echo_lock);
736 add_echo_byte(ECHO_OP_START, tty);
737 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
739 mutex_unlock(&tty->echo_lock);
743 * echo_erase_tab - add operation to erase a tab
744 * @num_chars: number of character columns already used
745 * @after_tab: true if num_chars starts after a previous tab
746 * @tty: terminal device
748 * Add an operation to the echo buffer to erase a tab.
750 * Called by the eraser function, which knows how many character
751 * columns have been used since either a previous tab or the start
752 * of input. This information will be used later, along with
753 * canon column (if applicable), to go back the correct number
756 * Locking: echo_lock to protect the echo buffer
759 static void echo_erase_tab(unsigned int num_chars, int after_tab,
760 struct tty_struct *tty)
762 mutex_lock(&tty->echo_lock);
764 add_echo_byte(ECHO_OP_START, tty);
765 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
767 /* We only need to know this modulo 8 (tab spacing) */
770 /* Set the high bit as a flag if num_chars is after a previous tab */
774 add_echo_byte(num_chars, tty);
776 mutex_unlock(&tty->echo_lock);
780 * echo_char_raw - echo a character raw
781 * @c: unicode byte to echo
782 * @tty: terminal device
784 * Echo user input back onto the screen. This must be called only when
785 * L_ECHO(tty) is true. Called from the driver receive_buf path.
787 * This variant does not treat control characters specially.
789 * Locking: echo_lock to protect the echo buffer
792 static void echo_char_raw(unsigned char c, struct tty_struct *tty)
794 mutex_lock(&tty->echo_lock);
796 if (c == ECHO_OP_START) {
797 add_echo_byte(ECHO_OP_START, tty);
798 add_echo_byte(ECHO_OP_START, tty);
800 add_echo_byte(c, tty);
803 mutex_unlock(&tty->echo_lock);
807 * echo_char - echo a character
808 * @c: unicode byte to echo
809 * @tty: terminal device
811 * Echo user input back onto the screen. This must be called only when
812 * L_ECHO(tty) is true. Called from the driver receive_buf path.
814 * This variant tags control characters to be possibly echoed as
815 * as "^X" (where X is the letter representing the control char).
817 * Locking: echo_lock to protect the echo buffer
820 static void echo_char(unsigned char c, struct tty_struct *tty)
822 mutex_lock(&tty->echo_lock);
824 if (c == ECHO_OP_START) {
825 add_echo_byte(ECHO_OP_START, tty);
826 add_echo_byte(ECHO_OP_START, tty);
828 if (iscntrl(c) && c != '\t')
829 add_echo_byte(ECHO_OP_START, tty);
830 add_echo_byte(c, tty);
833 mutex_unlock(&tty->echo_lock);
837 * finish_erasing - complete erase
838 * @tty: tty doing the erase
841 static inline void finish_erasing(struct tty_struct *tty)
844 echo_char_raw('/', tty);
850 * eraser - handle erase function
851 * @c: character input
852 * @tty: terminal device
854 * Perform erase and necessary output when an erase character is
855 * present in the stream from the driver layer. Handles the complexities
856 * of UTF-8 multibyte symbols.
858 * Locking: read_lock for tty buffers
861 static void eraser(unsigned char c, struct tty_struct *tty)
863 enum { ERASE, WERASE, KILL } kill_type;
864 int head, seen_alnums, cnt;
867 /* FIXME: locking needed ? */
868 if (tty->read_head == tty->canon_head) {
869 /* echo_char_raw('\a', tty); */ /* what do you think? */
872 if (c == ERASE_CHAR(tty))
874 else if (c == WERASE_CHAR(tty))
878 spin_lock_irqsave(&tty->read_lock, flags);
879 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
880 (N_TTY_BUF_SIZE - 1));
881 tty->read_head = tty->canon_head;
882 spin_unlock_irqrestore(&tty->read_lock, flags);
885 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
886 spin_lock_irqsave(&tty->read_lock, flags);
887 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
888 (N_TTY_BUF_SIZE - 1));
889 tty->read_head = tty->canon_head;
890 spin_unlock_irqrestore(&tty->read_lock, flags);
892 echo_char(KILL_CHAR(tty), tty);
893 /* Add a newline if ECHOK is on and ECHOKE is off. */
895 echo_char_raw('\n', tty);
902 /* FIXME: Locking ?? */
903 while (tty->read_head != tty->canon_head) {
904 head = tty->read_head;
906 /* erase a single possibly multibyte character */
908 head = (head - 1) & (N_TTY_BUF_SIZE-1);
909 c = tty->read_buf[head];
910 } while (is_continuation(c, tty) && head != tty->canon_head);
912 /* do not partially erase */
913 if (is_continuation(c, tty))
916 if (kill_type == WERASE) {
917 /* Equivalent to BSD's ALTWERASE. */
918 if (isalnum(c) || c == '_')
920 else if (seen_alnums)
923 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
924 spin_lock_irqsave(&tty->read_lock, flags);
925 tty->read_head = head;
926 tty->read_cnt -= cnt;
927 spin_unlock_irqrestore(&tty->read_lock, flags);
929 if (L_ECHOPRT(tty)) {
931 echo_char_raw('\\', tty);
934 /* if cnt > 1, output a multi-byte character */
937 head = (head+1) & (N_TTY_BUF_SIZE-1);
938 echo_char_raw(tty->read_buf[head], tty);
939 echo_move_back_col(tty);
941 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
942 echo_char(ERASE_CHAR(tty), tty);
943 } else if (c == '\t') {
944 unsigned int num_chars = 0;
946 unsigned long tail = tty->read_head;
949 * Count the columns used for characters
950 * since the start of input or after a
952 * This info is used to go back the correct
955 while (tail != tty->canon_head) {
956 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
957 c = tty->read_buf[tail];
961 } else if (iscntrl(c)) {
964 } else if (!is_continuation(c, tty)) {
968 echo_erase_tab(num_chars, after_tab, tty);
970 if (iscntrl(c) && L_ECHOCTL(tty)) {
971 echo_char_raw('\b', tty);
972 echo_char_raw(' ', tty);
973 echo_char_raw('\b', tty);
975 if (!iscntrl(c) || L_ECHOCTL(tty)) {
976 echo_char_raw('\b', tty);
977 echo_char_raw(' ', tty);
978 echo_char_raw('\b', tty);
982 if (kill_type == ERASE)
985 if (tty->read_head == tty->canon_head && L_ECHO(tty))
990 * isig - handle the ISIG optio
993 * @flush: force flush
995 * Called when a signal is being sent due to terminal input. This
996 * may caus terminal flushing to take place according to the termios
997 * settings and character used. Called from the driver receive_buf
998 * path so serialized.
1000 * Locking: ctrl_lock, read_lock (both via flush buffer)
1003 static inline void isig(int sig, struct tty_struct *tty, int flush)
1006 kill_pgrp(tty->pgrp, sig, 1);
1007 if (flush || !L_NOFLSH(tty)) {
1008 n_tty_flush_buffer(tty);
1009 tty_driver_flush_buffer(tty);
1014 * n_tty_receive_break - handle break
1017 * An RS232 break event has been hit in the incoming bitstream. This
1018 * can cause a variety of events depending upon the termios settings.
1020 * Called from the receive_buf path so single threaded.
1023 static inline void n_tty_receive_break(struct tty_struct *tty)
1027 if (I_BRKINT(tty)) {
1028 isig(SIGINT, tty, 1);
1031 if (I_PARMRK(tty)) {
1032 put_tty_queue('\377', tty);
1033 put_tty_queue('\0', tty);
1035 put_tty_queue('\0', tty);
1036 wake_up_interruptible(&tty->read_wait);
1040 * n_tty_receive_overrun - handle overrun reporting
1043 * Data arrived faster than we could process it. While the tty
1044 * driver has flagged this the bits that were missed are gone
1047 * Called from the receive_buf path so single threaded. Does not
1048 * need locking as num_overrun and overrun_time are function
1052 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1057 if (time_before(tty->overrun_time, jiffies - HZ) ||
1058 time_after(tty->overrun_time, jiffies)) {
1059 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1062 tty->overrun_time = jiffies;
1063 tty->num_overrun = 0;
1068 * n_tty_receive_parity_error - error notifier
1069 * @tty: terminal device
1072 * Process a parity error and queue the right data to indicate
1073 * the error case if necessary. Locking as per n_tty_receive_buf.
1075 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1080 if (I_PARMRK(tty)) {
1081 put_tty_queue('\377', tty);
1082 put_tty_queue('\0', tty);
1083 put_tty_queue(c, tty);
1084 } else if (I_INPCK(tty))
1085 put_tty_queue('\0', tty);
1087 put_tty_queue(c, tty);
1088 wake_up_interruptible(&tty->read_wait);
1092 * n_tty_receive_char - perform processing
1093 * @tty: terminal device
1096 * Process an individual character of input received from the driver.
1097 * This is serialized with respect to itself by the rules for the
1101 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1103 unsigned long flags;
1106 put_tty_queue(c, tty);
1112 if (I_IUCLC(tty) && L_IEXTEN(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) {
1142 finish_erasing(tty);
1143 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
1144 /* beep if no space */
1145 echo_char_raw('\a', tty);
1146 process_echoes(tty);
1149 /* Record the column of first canon char. */
1150 if (tty->canon_head == tty->read_head)
1151 echo_set_canon_col(tty);
1153 process_echoes(tty);
1155 if (I_PARMRK(tty) && c == (unsigned char) '\377')
1156 put_tty_queue(c, tty);
1157 put_tty_queue(c, tty);
1162 if (c == START_CHAR(tty)) {
1164 process_echoes(tty);
1167 if (c == STOP_CHAR(tty)) {
1176 if (c == INTR_CHAR(tty))
1179 if (c == QUIT_CHAR(tty))
1182 if (c == SUSP_CHAR(tty)) {
1185 * Note that we do not use isig() here because we want
1187 * 1) flush, 2) echo, 3) signal
1189 if (!L_NOFLSH(tty)) {
1190 n_tty_flush_buffer(tty);
1191 tty_driver_flush_buffer(tty);
1197 process_echoes(tty);
1200 kill_pgrp(tty->pgrp, signal, 1);
1210 } else if (c == '\n' && I_INLCR(tty))
1214 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1215 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1217 process_echoes(tty);
1220 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1223 finish_erasing(tty);
1224 if (L_ECHOCTL(tty)) {
1225 echo_char_raw('^', tty);
1226 echo_char_raw('\b', tty);
1227 process_echoes(tty);
1232 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1234 unsigned long tail = tty->canon_head;
1236 finish_erasing(tty);
1238 echo_char_raw('\n', tty);
1239 while (tail != tty->read_head) {
1240 echo_char(tty->read_buf[tail], tty);
1241 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1243 process_echoes(tty);
1247 if (L_ECHO(tty) || L_ECHONL(tty)) {
1248 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
1249 echo_char_raw('\a', tty);
1250 echo_char_raw('\n', tty);
1251 process_echoes(tty);
1253 goto handle_newline;
1255 if (c == EOF_CHAR(tty)) {
1256 if (tty->canon_head != tty->read_head)
1257 set_bit(TTY_PUSH, &tty->flags);
1258 c = __DISABLED_CHAR;
1259 goto handle_newline;
1261 if ((c == EOL_CHAR(tty)) ||
1262 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1264 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1267 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
1268 echo_char_raw('\a', tty);
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?
1279 if (I_PARMRK(tty) && c == (unsigned char) '\377')
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);
1297 finish_erasing(tty);
1298 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
1299 /* beep if no space */
1300 echo_char_raw('\a', tty);
1301 process_echoes(tty);
1305 echo_char_raw('\n', tty);
1307 /* Record the column of first canon char. */
1308 if (tty->canon_head == tty->read_head)
1309 echo_set_canon_col(tty);
1312 process_echoes(tty);
1315 if (I_PARMRK(tty) && c == (unsigned char) '\377')
1316 put_tty_queue(c, tty);
1318 put_tty_queue(c, tty);
1323 * n_tty_write_wakeup - asynchronous I/O notifier
1326 * Required for the ptys, serial driver etc. since processes
1327 * that attach themselves to the master and rely on ASYNC
1328 * IO must be woken up
1331 static void n_tty_write_wakeup(struct tty_struct *tty)
1333 /* Write out any echoed characters that are still pending */
1334 process_echoes(tty);
1337 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
1338 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1343 * n_tty_receive_buf - data receive
1344 * @tty: terminal device
1347 * @count: characters
1349 * Called by the terminal driver when a block of characters has
1350 * been received. This function must be called from soft contexts
1351 * not from interrupt context. The driver is responsible for making
1352 * calls one at a time and in order (or using flush_to_ldisc)
1355 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1356 char *fp, int count)
1358 const unsigned char *p;
1359 char *f, flags = TTY_NORMAL;
1362 unsigned long cpuflags;
1367 if (tty->real_raw) {
1368 spin_lock_irqsave(&tty->read_lock, cpuflags);
1369 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1370 N_TTY_BUF_SIZE - tty->read_head);
1372 memcpy(tty->read_buf + tty->read_head, cp, i);
1373 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1378 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1379 N_TTY_BUF_SIZE - tty->read_head);
1381 memcpy(tty->read_buf + tty->read_head, cp, i);
1382 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1384 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1386 for (i = count, p = cp, f = fp; i; i--, p++) {
1391 n_tty_receive_char(tty, *p);
1394 n_tty_receive_break(tty);
1398 n_tty_receive_parity_error(tty, *p);
1401 n_tty_receive_overrun(tty);
1404 printk(KERN_ERR "%s: unknown flag %d\n",
1405 tty_name(tty, buf), flags);
1409 if (tty->ops->flush_chars)
1410 tty->ops->flush_chars(tty);
1413 n_tty_set_room(tty);
1415 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
1416 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1417 if (waitqueue_active(&tty->read_wait))
1418 wake_up_interruptible(&tty->read_wait);
1422 * Check the remaining room for the input canonicalization
1423 * mode. We don't want to throttle the driver if we're in
1424 * canonical mode and don't have a newline yet!
1426 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1430 int is_ignored(int sig)
1432 return (sigismember(¤t->blocked, sig) ||
1433 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1437 * n_tty_set_termios - termios data changed
1439 * @old: previous data
1441 * Called by the tty layer when the user changes termios flags so
1442 * that the line discipline can plan ahead. This function cannot sleep
1443 * and is protected from re-entry by the tty layer. The user is
1444 * guaranteed that this function will not be re-entered or in progress
1445 * when the ldisc is closed.
1447 * Locking: Caller holds tty->termios_mutex
1450 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1452 int canon_change = 1;
1456 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1458 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1459 tty->canon_head = tty->read_tail;
1460 tty->canon_data = 0;
1464 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1465 wake_up_interruptible(&tty->read_wait);
1467 tty->icanon = (L_ICANON(tty) != 0);
1468 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1471 n_tty_set_room(tty);
1474 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1475 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1476 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1478 memset(tty->process_char_map, 0, 256/8);
1480 if (I_IGNCR(tty) || I_ICRNL(tty))
1481 set_bit('\r', tty->process_char_map);
1483 set_bit('\n', tty->process_char_map);
1485 if (L_ICANON(tty)) {
1486 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1487 set_bit(KILL_CHAR(tty), tty->process_char_map);
1488 set_bit(EOF_CHAR(tty), tty->process_char_map);
1489 set_bit('\n', tty->process_char_map);
1490 set_bit(EOL_CHAR(tty), tty->process_char_map);
1491 if (L_IEXTEN(tty)) {
1492 set_bit(WERASE_CHAR(tty),
1493 tty->process_char_map);
1494 set_bit(LNEXT_CHAR(tty),
1495 tty->process_char_map);
1496 set_bit(EOL2_CHAR(tty),
1497 tty->process_char_map);
1499 set_bit(REPRINT_CHAR(tty),
1500 tty->process_char_map);
1504 set_bit(START_CHAR(tty), tty->process_char_map);
1505 set_bit(STOP_CHAR(tty), tty->process_char_map);
1508 set_bit(INTR_CHAR(tty), tty->process_char_map);
1509 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1510 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1512 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1517 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1518 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1519 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1524 n_tty_set_room(tty);
1525 /* The termios change make the tty ready for I/O */
1526 wake_up_interruptible(&tty->write_wait);
1527 wake_up_interruptible(&tty->read_wait);
1531 * n_tty_close - close the ldisc for this tty
1534 * Called from the terminal layer when this line discipline is
1535 * being shut down, either because of a close or becsuse of a
1536 * discipline change. The function will not be called while other
1537 * ldisc methods are in progress.
1540 static void n_tty_close(struct tty_struct *tty)
1542 n_tty_flush_buffer(tty);
1543 if (tty->read_buf) {
1544 free_buf(tty->read_buf);
1545 tty->read_buf = NULL;
1547 if (tty->echo_buf) {
1548 free_buf(tty->echo_buf);
1549 tty->echo_buf = NULL;
1554 * n_tty_open - open an ldisc
1555 * @tty: terminal to open
1557 * Called when this line discipline is being attached to the
1558 * terminal device. Can sleep. Called serialized so that no
1559 * other events will occur in parallel. No further open will occur
1563 static int n_tty_open(struct tty_struct *tty)
1568 /* These are ugly. Currently a malloc failure here can panic */
1569 if (!tty->read_buf) {
1570 tty->read_buf = alloc_buf();
1574 if (!tty->echo_buf) {
1575 tty->echo_buf = alloc_buf();
1579 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1580 memset(tty->echo_buf, 0, N_TTY_BUF_SIZE);
1581 reset_buffer_flags(tty);
1583 n_tty_set_termios(tty, NULL);
1584 tty->minimum_to_wake = 1;
1589 static inline int input_available_p(struct tty_struct *tty, int amt)
1592 if (tty->canon_data)
1594 } else if (tty->read_cnt >= (amt ? amt : 1))
1601 * copy_from_read_buf - copy read data directly
1602 * @tty: terminal device
1606 * Helper function to speed up n_tty_read. It is only called when
1607 * ICANON is off; it copies characters straight from the tty queue to
1608 * user space directly. It can be profitably called twice; once to
1609 * drain the space from the tail pointer to the (physical) end of the
1610 * buffer, and once to drain the space from the (physical) beginning of
1611 * the buffer to head pointer.
1613 * Called under the tty->atomic_read_lock sem
1617 static int copy_from_read_buf(struct tty_struct *tty,
1618 unsigned char __user **b,
1624 unsigned long flags;
1627 spin_lock_irqsave(&tty->read_lock, flags);
1628 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1630 spin_unlock_irqrestore(&tty->read_lock, flags);
1632 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1634 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1635 spin_lock_irqsave(&tty->read_lock, flags);
1636 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1638 spin_unlock_irqrestore(&tty->read_lock, flags);
1645 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1649 * job_control - check job control
1651 * @file: file handle
1653 * Perform job control management checks on this file/tty descriptor
1654 * and if appropriate send any needed signals and return a negative
1655 * error code if action should be taken.
1658 * Locking: None - redirected write test is safe, testing
1659 * current->signal should possibly lock current->sighand
1663 static int job_control(struct tty_struct *tty, struct file *file)
1665 /* Job control check -- must be done at start and after
1666 every sleep (POSIX.1 7.1.1.4). */
1667 /* NOTE: not yet done after every sleep pending a thorough
1668 check of the logic of this change. -- jlc */
1669 /* don't stop on /dev/console */
1670 if (file->f_op->write != redirected_tty_write &&
1671 current->signal->tty == tty) {
1673 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1674 else if (task_pgrp(current) != tty->pgrp) {
1675 if (is_ignored(SIGTTIN) ||
1676 is_current_pgrp_orphaned())
1678 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1679 set_thread_flag(TIF_SIGPENDING);
1680 return -ERESTARTSYS;
1688 * n_tty_read - read function for tty
1690 * @file: file object
1691 * @buf: userspace buffer pointer
1694 * Perform reads for the line discipline. We are guaranteed that the
1695 * line discipline will not be closed under us but we may get multiple
1696 * parallel readers and must handle this ourselves. We may also get
1697 * a hangup. Always called in user context, may sleep.
1699 * This code must be sure never to sleep through a hangup.
1702 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1703 unsigned char __user *buf, size_t nr)
1705 unsigned char __user *b = buf;
1706 DECLARE_WAITQUEUE(wait, current);
1712 unsigned long flags;
1717 BUG_ON(!tty->read_buf);
1719 c = job_control(tty, file);
1724 timeout = MAX_SCHEDULE_TIMEOUT;
1726 time = (HZ / 10) * TIME_CHAR(tty);
1727 minimum = MIN_CHAR(tty);
1730 tty->minimum_to_wake = 1;
1731 else if (!waitqueue_active(&tty->read_wait) ||
1732 (tty->minimum_to_wake > minimum))
1733 tty->minimum_to_wake = minimum;
1740 tty->minimum_to_wake = minimum = 1;
1745 * Internal serialization of reads.
1747 if (file->f_flags & O_NONBLOCK) {
1748 if (!mutex_trylock(&tty->atomic_read_lock))
1751 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1752 return -ERESTARTSYS;
1754 packet = tty->packet;
1756 add_wait_queue(&tty->read_wait, &wait);
1758 /* First test for status change. */
1759 if (packet && tty->link->ctrl_status) {
1763 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1764 cs = tty->link->ctrl_status;
1765 tty->link->ctrl_status = 0;
1766 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1767 if (tty_put_user(tty, cs, b++)) {
1775 /* This statement must be first before checking for input
1776 so that any interrupt will set the state back to
1778 set_current_state(TASK_INTERRUPTIBLE);
1780 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1781 ((minimum - (b - buf)) >= 1))
1782 tty->minimum_to_wake = (minimum - (b - buf));
1784 if (!input_available_p(tty, 0)) {
1785 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1789 if (tty_hung_up_p(file))
1793 if (file->f_flags & O_NONBLOCK) {
1797 if (signal_pending(current)) {
1798 retval = -ERESTARTSYS;
1801 /* FIXME: does n_tty_set_room need locking ? */
1802 n_tty_set_room(tty);
1803 timeout = schedule_timeout(timeout);
1806 __set_current_state(TASK_RUNNING);
1808 /* Deal with packet mode. */
1809 if (packet && b == buf) {
1810 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1819 /* N.B. avoid overrun if nr == 0 */
1820 while (nr && tty->read_cnt) {
1823 eol = test_and_clear_bit(tty->read_tail,
1825 c = tty->read_buf[tty->read_tail];
1826 spin_lock_irqsave(&tty->read_lock, flags);
1827 tty->read_tail = ((tty->read_tail+1) &
1828 (N_TTY_BUF_SIZE-1));
1831 /* this test should be redundant:
1832 * we shouldn't be reading data if
1835 if (--tty->canon_data < 0)
1836 tty->canon_data = 0;
1838 spin_unlock_irqrestore(&tty->read_lock, flags);
1840 if (!eol || (c != __DISABLED_CHAR)) {
1841 if (tty_put_user(tty, c, b++)) {
1849 tty_audit_push(tty);
1857 /* The copy function takes the read lock and handles
1858 locking internally for this case */
1859 uncopied = copy_from_read_buf(tty, &b, &nr);
1860 uncopied += copy_from_read_buf(tty, &b, &nr);
1867 /* If there is enough space in the read buffer now, let the
1868 * low-level driver know. We use n_tty_chars_in_buffer() to
1869 * check the buffer, as it now knows about canonical mode.
1870 * Otherwise, if the driver is throttled and the line is
1871 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1872 * we won't get any more characters.
1874 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1875 n_tty_set_room(tty);
1876 check_unthrottle(tty);
1879 if (b - buf >= minimum)
1884 mutex_unlock(&tty->atomic_read_lock);
1885 remove_wait_queue(&tty->read_wait, &wait);
1887 if (!waitqueue_active(&tty->read_wait))
1888 tty->minimum_to_wake = minimum;
1890 __set_current_state(TASK_RUNNING);
1895 clear_bit(TTY_PUSH, &tty->flags);
1896 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1899 n_tty_set_room(tty);
1904 * n_tty_write - write function for tty
1906 * @file: file object
1907 * @buf: userspace buffer pointer
1910 * Write function of the terminal device. This is serialized with
1911 * respect to other write callers but not to termios changes, reads
1912 * and other such events. Since the receive code will echo characters,
1913 * thus calling driver write methods, the output_lock is used in
1914 * the output processing functions called here as well as in the
1915 * echo processing function to protect the column state and space
1916 * left in the buffer.
1918 * This code must be sure never to sleep through a hangup.
1920 * Locking: output_lock to protect column state and space left
1921 * (note that the process_output*() functions take this
1925 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1926 const unsigned char *buf, size_t nr)
1928 const unsigned char *b = buf;
1929 DECLARE_WAITQUEUE(wait, current);
1933 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1934 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1935 retval = tty_check_change(tty);
1940 /* Write out any echoed characters that are still pending */
1941 process_echoes(tty);
1943 add_wait_queue(&tty->write_wait, &wait);
1945 set_current_state(TASK_INTERRUPTIBLE);
1946 if (signal_pending(current)) {
1947 retval = -ERESTARTSYS;
1950 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1954 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1956 ssize_t num = process_output_block(tty, b, nr);
1968 if (process_output(c, tty) < 0)
1972 if (tty->ops->flush_chars)
1973 tty->ops->flush_chars(tty);
1976 c = tty->ops->write(tty, b, nr);
1989 if (file->f_flags & O_NONBLOCK) {
1996 __set_current_state(TASK_RUNNING);
1997 remove_wait_queue(&tty->write_wait, &wait);
1998 return (b - buf) ? b - buf : retval;
2002 * n_tty_poll - poll method for N_TTY
2003 * @tty: terminal device
2004 * @file: file accessing it
2007 * Called when the line discipline is asked to poll() for data or
2008 * for special events. This code is not serialized with respect to
2009 * other events save open/close.
2011 * This code must be sure never to sleep through a hangup.
2012 * Called without the kernel lock held - fine
2015 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2018 unsigned int mask = 0;
2020 poll_wait(file, &tty->read_wait, wait);
2021 poll_wait(file, &tty->write_wait, wait);
2022 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2023 mask |= POLLIN | POLLRDNORM;
2024 if (tty->packet && tty->link->ctrl_status)
2025 mask |= POLLPRI | POLLIN | POLLRDNORM;
2026 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2028 if (tty_hung_up_p(file))
2030 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2031 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2032 tty->minimum_to_wake = MIN_CHAR(tty);
2034 tty->minimum_to_wake = 1;
2036 if (tty->ops->write && !tty_is_writelocked(tty) &&
2037 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2038 tty_write_room(tty) > 0)
2039 mask |= POLLOUT | POLLWRNORM;
2043 static unsigned long inq_canon(struct tty_struct *tty)
2047 if (!tty->canon_data)
2049 head = tty->canon_head;
2050 tail = tty->read_tail;
2051 nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2052 /* Skip EOF-chars.. */
2053 while (head != tail) {
2054 if (test_bit(tail, tty->read_flags) &&
2055 tty->read_buf[tail] == __DISABLED_CHAR)
2057 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2062 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2063 unsigned int cmd, unsigned long arg)
2069 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2071 /* FIXME: Locking */
2072 retval = tty->read_cnt;
2074 retval = inq_canon(tty);
2075 return put_user(retval, (unsigned int __user *) arg);
2077 return n_tty_ioctl_helper(tty, file, cmd, arg);
2081 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2082 .magic = TTY_LDISC_MAGIC,
2085 .close = n_tty_close,
2086 .flush_buffer = n_tty_flush_buffer,
2087 .chars_in_buffer = n_tty_chars_in_buffer,
2089 .write = n_tty_write,
2090 .ioctl = n_tty_ioctl,
2091 .set_termios = n_tty_set_termios,
2093 .receive_buf = n_tty_receive_buf,
2094 .write_wakeup = n_tty_write_wakeup