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;
357 if (!is_continuation(c, tty))
363 tty_put_char(tty, c);
368 * process_output - output post processor
369 * @c: character (or partial unicode symbol)
370 * @tty: terminal device
372 * Perform OPOST processing. Returns -1 when the output device is
373 * full and the character must be retried.
375 * Locking: output_lock to protect column state and space left
376 * (also, this is called from n_tty_write under the
377 * tty layer write lock)
380 static int process_output(unsigned char c, struct tty_struct *tty)
384 mutex_lock(&tty->output_lock);
386 space = tty_write_room(tty);
387 retval = do_output_char(c, tty, space);
389 mutex_unlock(&tty->output_lock);
397 * process_output_block - block post processor
398 * @tty: terminal device
399 * @inbuf: user buffer
400 * @nr: number of bytes
402 * This path is used to speed up block console writes, among other
403 * things when processing blocks of output data. It handles only
404 * the simple cases normally found and helps to generate blocks of
405 * symbols for the console driver and thus improve performance.
407 * Locking: output_lock to protect column state and space left
408 * (also, this is called from n_tty_write under the
409 * tty layer write lock)
412 static ssize_t process_output_block(struct tty_struct *tty,
413 const unsigned char *buf, unsigned int nr)
417 const unsigned char *cp;
419 mutex_lock(&tty->output_lock);
421 space = tty_write_room(tty);
423 mutex_unlock(&tty->output_lock);
429 for (i = 0, cp = buf; i < nr; i++, cp++) {
430 unsigned char c = *cp;
438 tty->canon_column = tty->column;
441 if (O_ONOCR(tty) && tty->column == 0)
445 tty->canon_column = tty->column = 0;
457 if (!is_continuation(c, tty))
464 i = tty->ops->write(tty, buf, i);
466 mutex_unlock(&tty->output_lock);
471 * process_echoes - write pending echo characters
472 * @tty: terminal device
474 * Write previously buffered echo (and other ldisc-generated)
475 * characters to the tty.
477 * Characters generated by the ldisc (including echoes) need to
478 * be buffered because the driver's write buffer can fill during
479 * heavy program output. Echoing straight to the driver will
480 * often fail under these conditions, causing lost characters and
481 * resulting mismatches of ldisc state information.
483 * Since the ldisc state must represent the characters actually sent
484 * to the driver at the time of the write, operations like certain
485 * changes in column state are also saved in the buffer and executed
488 * A circular fifo buffer is used so that the most recent characters
489 * are prioritized. Also, when control characters are echoed with a
490 * prefixed "^", the pair is treated atomically and thus not separated.
492 * Locking: output_lock to protect column state and space left,
493 * echo_lock to protect the echo buffer
496 static void process_echoes(struct tty_struct *tty)
500 unsigned char *cp, *buf_end;
505 mutex_lock(&tty->output_lock);
506 mutex_lock(&tty->echo_lock);
508 space = tty_write_room(tty);
510 buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
511 cp = tty->echo_buf + tty->echo_pos;
515 if (c == ECHO_OP_START) {
518 int no_space_left = 0;
521 * If the buffer byte is the start of a multi-byte
522 * operation, get the next byte, which is either the
523 * op code or a control character value.
527 opp -= N_TTY_BUF_SIZE;
531 unsigned int num_chars, num_bs;
533 case ECHO_OP_ERASE_TAB:
534 if (++opp == buf_end)
535 opp -= N_TTY_BUF_SIZE;
539 * Determine how many columns to go back
540 * in order to erase the tab.
541 * This depends on the number of columns
542 * used by other characters within the tab
543 * area. If this (modulo 8) count is from
544 * the start of input rather than from a
545 * previous tab, we offset by canon column.
546 * Otherwise, tab spacing is normal.
548 if (!(num_chars & 0x80))
549 num_chars += tty->canon_column;
550 num_bs = 8 - (num_chars & 7);
552 if (num_bs > space) {
558 tty_put_char(tty, '\b');
566 case ECHO_OP_SET_CANON_COL:
567 tty->canon_column = tty->column;
572 case ECHO_OP_MOVE_BACK_COL:
580 /* This is an escaped echo op start code */
585 tty_put_char(tty, ECHO_OP_START);
594 if (L_ECHOCTL(tty)) {
596 * Ensure there is enough space
597 * for the whole ctrl pair.
603 tty_put_char(tty, '^');
604 tty_put_char(tty, op ^ 0100);
612 tty_put_char(tty, op);
617 * If above falls through, this was an
629 retval = do_output_char(c, tty, space);
637 /* When end of circular buffer reached, wrap around */
639 cp -= N_TTY_BUF_SIZE;
645 tty->echo_overrun = 0;
647 int num_processed = tty->echo_cnt - nr;
648 tty->echo_pos += num_processed;
649 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
651 if (num_processed > 0)
652 tty->echo_overrun = 0;
655 mutex_unlock(&tty->echo_lock);
656 mutex_unlock(&tty->output_lock);
658 if (tty->ops->flush_chars)
659 tty->ops->flush_chars(tty);
663 * add_echo_byte - add a byte to the echo buffer
664 * @c: unicode byte to echo
665 * @tty: terminal device
667 * Add a character or operation byte to the echo buffer.
669 * Should be called under the echo lock to protect the echo buffer.
672 static void add_echo_byte(unsigned char c, struct tty_struct *tty)
676 if (tty->echo_cnt == N_TTY_BUF_SIZE) {
677 /* Circular buffer is already at capacity */
678 new_byte_pos = tty->echo_pos;
681 * Since the buffer start position needs to be advanced,
682 * be sure to step by a whole operation byte group.
684 if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
685 if (tty->echo_buf[(tty->echo_pos + 1) &
686 (N_TTY_BUF_SIZE - 1)] ==
697 tty->echo_pos &= N_TTY_BUF_SIZE - 1;
699 tty->echo_overrun = 1;
701 new_byte_pos = tty->echo_pos + tty->echo_cnt;
702 new_byte_pos &= N_TTY_BUF_SIZE - 1;
706 tty->echo_buf[new_byte_pos] = c;
710 * echo_move_back_col - add operation to move back a column
711 * @tty: terminal device
713 * Add an operation to the echo buffer to move back one column.
715 * Locking: echo_lock to protect the echo buffer
718 static void echo_move_back_col(struct tty_struct *tty)
720 mutex_lock(&tty->echo_lock);
722 add_echo_byte(ECHO_OP_START, tty);
723 add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
725 mutex_unlock(&tty->echo_lock);
729 * echo_set_canon_col - add operation to set the canon column
730 * @tty: terminal device
732 * Add an operation to the echo buffer to set the canon column
733 * to the current column.
735 * Locking: echo_lock to protect the echo buffer
738 static void echo_set_canon_col(struct tty_struct *tty)
740 mutex_lock(&tty->echo_lock);
742 add_echo_byte(ECHO_OP_START, tty);
743 add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
745 mutex_unlock(&tty->echo_lock);
749 * echo_erase_tab - add operation to erase a tab
750 * @num_chars: number of character columns already used
751 * @after_tab: true if num_chars starts after a previous tab
752 * @tty: terminal device
754 * Add an operation to the echo buffer to erase a tab.
756 * Called by the eraser function, which knows how many character
757 * columns have been used since either a previous tab or the start
758 * of input. This information will be used later, along with
759 * canon column (if applicable), to go back the correct number
762 * Locking: echo_lock to protect the echo buffer
765 static void echo_erase_tab(unsigned int num_chars, int after_tab,
766 struct tty_struct *tty)
768 mutex_lock(&tty->echo_lock);
770 add_echo_byte(ECHO_OP_START, tty);
771 add_echo_byte(ECHO_OP_ERASE_TAB, tty);
773 /* We only need to know this modulo 8 (tab spacing) */
776 /* Set the high bit as a flag if num_chars is after a previous tab */
780 add_echo_byte(num_chars, tty);
782 mutex_unlock(&tty->echo_lock);
786 * echo_char_raw - echo a character raw
787 * @c: unicode byte to echo
788 * @tty: terminal device
790 * Echo user input back onto the screen. This must be called only when
791 * L_ECHO(tty) is true. Called from the driver receive_buf path.
793 * This variant does not treat control characters specially.
795 * Locking: echo_lock to protect the echo buffer
798 static void echo_char_raw(unsigned char c, struct tty_struct *tty)
800 mutex_lock(&tty->echo_lock);
802 if (c == ECHO_OP_START) {
803 add_echo_byte(ECHO_OP_START, tty);
804 add_echo_byte(ECHO_OP_START, tty);
806 add_echo_byte(c, tty);
809 mutex_unlock(&tty->echo_lock);
813 * echo_char - echo a character
814 * @c: unicode byte to echo
815 * @tty: terminal device
817 * Echo user input back onto the screen. This must be called only when
818 * L_ECHO(tty) is true. Called from the driver receive_buf path.
820 * This variant tags control characters to be possibly echoed as
821 * as "^X" (where X is the letter representing the control char).
823 * Locking: echo_lock to protect the echo buffer
826 static void echo_char(unsigned char c, struct tty_struct *tty)
828 mutex_lock(&tty->echo_lock);
830 if (c == ECHO_OP_START) {
831 add_echo_byte(ECHO_OP_START, tty);
832 add_echo_byte(ECHO_OP_START, tty);
834 if (iscntrl(c) && c != '\t')
835 add_echo_byte(ECHO_OP_START, tty);
836 add_echo_byte(c, tty);
839 mutex_unlock(&tty->echo_lock);
843 * finish_erasing - complete erase
844 * @tty: tty doing the erase
847 static inline void finish_erasing(struct tty_struct *tty)
850 echo_char_raw('/', tty);
856 * eraser - handle erase function
857 * @c: character input
858 * @tty: terminal device
860 * Perform erase and necessary output when an erase character is
861 * present in the stream from the driver layer. Handles the complexities
862 * of UTF-8 multibyte symbols.
864 * Locking: read_lock for tty buffers
867 static void eraser(unsigned char c, struct tty_struct *tty)
869 enum { ERASE, WERASE, KILL } kill_type;
870 int head, seen_alnums, cnt;
873 /* FIXME: locking needed ? */
874 if (tty->read_head == tty->canon_head) {
875 /* echo_char_raw('\a', tty); */ /* what do you think? */
878 if (c == ERASE_CHAR(tty))
880 else if (c == WERASE_CHAR(tty))
884 spin_lock_irqsave(&tty->read_lock, flags);
885 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
886 (N_TTY_BUF_SIZE - 1));
887 tty->read_head = tty->canon_head;
888 spin_unlock_irqrestore(&tty->read_lock, flags);
891 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
892 spin_lock_irqsave(&tty->read_lock, flags);
893 tty->read_cnt -= ((tty->read_head - tty->canon_head) &
894 (N_TTY_BUF_SIZE - 1));
895 tty->read_head = tty->canon_head;
896 spin_unlock_irqrestore(&tty->read_lock, flags);
898 echo_char(KILL_CHAR(tty), tty);
899 /* Add a newline if ECHOK is on and ECHOKE is off. */
901 echo_char_raw('\n', tty);
908 /* FIXME: Locking ?? */
909 while (tty->read_head != tty->canon_head) {
910 head = tty->read_head;
912 /* erase a single possibly multibyte character */
914 head = (head - 1) & (N_TTY_BUF_SIZE-1);
915 c = tty->read_buf[head];
916 } while (is_continuation(c, tty) && head != tty->canon_head);
918 /* do not partially erase */
919 if (is_continuation(c, tty))
922 if (kill_type == WERASE) {
923 /* Equivalent to BSD's ALTWERASE. */
924 if (isalnum(c) || c == '_')
926 else if (seen_alnums)
929 cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
930 spin_lock_irqsave(&tty->read_lock, flags);
931 tty->read_head = head;
932 tty->read_cnt -= cnt;
933 spin_unlock_irqrestore(&tty->read_lock, flags);
935 if (L_ECHOPRT(tty)) {
937 echo_char_raw('\\', tty);
940 /* if cnt > 1, output a multi-byte character */
943 head = (head+1) & (N_TTY_BUF_SIZE-1);
944 echo_char_raw(tty->read_buf[head], tty);
945 echo_move_back_col(tty);
947 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
948 echo_char(ERASE_CHAR(tty), tty);
949 } else if (c == '\t') {
950 unsigned int num_chars = 0;
952 unsigned long tail = tty->read_head;
955 * Count the columns used for characters
956 * since the start of input or after a
958 * This info is used to go back the correct
961 while (tail != tty->canon_head) {
962 tail = (tail-1) & (N_TTY_BUF_SIZE-1);
963 c = tty->read_buf[tail];
967 } else if (iscntrl(c)) {
970 } else if (!is_continuation(c, tty)) {
974 echo_erase_tab(num_chars, after_tab, tty);
976 if (iscntrl(c) && L_ECHOCTL(tty)) {
977 echo_char_raw('\b', tty);
978 echo_char_raw(' ', tty);
979 echo_char_raw('\b', tty);
981 if (!iscntrl(c) || L_ECHOCTL(tty)) {
982 echo_char_raw('\b', tty);
983 echo_char_raw(' ', tty);
984 echo_char_raw('\b', tty);
988 if (kill_type == ERASE)
991 if (tty->read_head == tty->canon_head && L_ECHO(tty))
996 * isig - handle the ISIG optio
999 * @flush: force flush
1001 * Called when a signal is being sent due to terminal input. This
1002 * may caus terminal flushing to take place according to the termios
1003 * settings and character used. Called from the driver receive_buf
1004 * path so serialized.
1006 * Locking: ctrl_lock, read_lock (both via flush buffer)
1009 static inline void isig(int sig, struct tty_struct *tty, int flush)
1012 kill_pgrp(tty->pgrp, sig, 1);
1013 if (flush || !L_NOFLSH(tty)) {
1014 n_tty_flush_buffer(tty);
1015 tty_driver_flush_buffer(tty);
1020 * n_tty_receive_break - handle break
1023 * An RS232 break event has been hit in the incoming bitstream. This
1024 * can cause a variety of events depending upon the termios settings.
1026 * Called from the receive_buf path so single threaded.
1029 static inline void n_tty_receive_break(struct tty_struct *tty)
1033 if (I_BRKINT(tty)) {
1034 isig(SIGINT, tty, 1);
1037 if (I_PARMRK(tty)) {
1038 put_tty_queue('\377', tty);
1039 put_tty_queue('\0', tty);
1041 put_tty_queue('\0', tty);
1042 wake_up_interruptible(&tty->read_wait);
1046 * n_tty_receive_overrun - handle overrun reporting
1049 * Data arrived faster than we could process it. While the tty
1050 * driver has flagged this the bits that were missed are gone
1053 * Called from the receive_buf path so single threaded. Does not
1054 * need locking as num_overrun and overrun_time are function
1058 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1063 if (time_before(tty->overrun_time, jiffies - HZ) ||
1064 time_after(tty->overrun_time, jiffies)) {
1065 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1068 tty->overrun_time = jiffies;
1069 tty->num_overrun = 0;
1074 * n_tty_receive_parity_error - error notifier
1075 * @tty: terminal device
1078 * Process a parity error and queue the right data to indicate
1079 * the error case if necessary. Locking as per n_tty_receive_buf.
1081 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1086 if (I_PARMRK(tty)) {
1087 put_tty_queue('\377', tty);
1088 put_tty_queue('\0', tty);
1089 put_tty_queue(c, tty);
1090 } else if (I_INPCK(tty))
1091 put_tty_queue('\0', tty);
1093 put_tty_queue(c, tty);
1094 wake_up_interruptible(&tty->read_wait);
1098 * n_tty_receive_char - perform processing
1099 * @tty: terminal device
1102 * Process an individual character of input received from the driver.
1103 * This is serialized with respect to itself by the rules for the
1107 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1109 unsigned long flags;
1112 put_tty_queue(c, tty);
1118 if (I_IUCLC(tty) && L_IEXTEN(tty))
1121 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1122 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1123 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1125 process_echoes(tty);
1130 if (c == START_CHAR(tty)) {
1132 process_echoes(tty);
1133 } else if (c == STOP_CHAR(tty))
1140 * If the previous character was LNEXT, or we know that this
1141 * character is not one of the characters that we'll have to
1142 * handle specially, do shortcut processing to speed things
1145 if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1148 finish_erasing(tty);
1149 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
1150 /* beep if no space */
1151 echo_char_raw('\a', tty);
1152 process_echoes(tty);
1155 /* Record the column of first canon char. */
1156 if (tty->canon_head == tty->read_head)
1157 echo_set_canon_col(tty);
1159 process_echoes(tty);
1161 if (I_PARMRK(tty) && c == (unsigned char) '\377')
1162 put_tty_queue(c, tty);
1163 put_tty_queue(c, tty);
1168 if (c == START_CHAR(tty)) {
1170 process_echoes(tty);
1173 if (c == STOP_CHAR(tty)) {
1182 if (c == INTR_CHAR(tty))
1185 if (c == QUIT_CHAR(tty))
1188 if (c == SUSP_CHAR(tty)) {
1191 * Note that we do not use isig() here because we want
1193 * 1) flush, 2) echo, 3) signal
1195 if (!L_NOFLSH(tty)) {
1196 n_tty_flush_buffer(tty);
1197 tty_driver_flush_buffer(tty);
1203 process_echoes(tty);
1206 kill_pgrp(tty->pgrp, signal, 1);
1216 } else if (c == '\n' && I_INLCR(tty))
1220 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1221 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1223 process_echoes(tty);
1226 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1229 finish_erasing(tty);
1230 if (L_ECHOCTL(tty)) {
1231 echo_char_raw('^', tty);
1232 echo_char_raw('\b', tty);
1233 process_echoes(tty);
1238 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1240 unsigned long tail = tty->canon_head;
1242 finish_erasing(tty);
1244 echo_char_raw('\n', tty);
1245 while (tail != tty->read_head) {
1246 echo_char(tty->read_buf[tail], tty);
1247 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1249 process_echoes(tty);
1253 if (L_ECHO(tty) || L_ECHONL(tty)) {
1254 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
1255 echo_char_raw('\a', tty);
1256 echo_char_raw('\n', tty);
1257 process_echoes(tty);
1259 goto handle_newline;
1261 if (c == EOF_CHAR(tty)) {
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))) {
1270 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1273 if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
1274 echo_char_raw('\a', tty);
1275 /* Record the column of first canon char. */
1276 if (tty->canon_head == tty->read_head)
1277 echo_set_canon_col(tty);
1279 process_echoes(tty);
1282 * XXX does PARMRK doubling happen for
1283 * EOL_CHAR and EOL2_CHAR?
1285 if (I_PARMRK(tty) && c == (unsigned char) '\377')
1286 put_tty_queue(c, tty);
1289 spin_lock_irqsave(&tty->read_lock, flags);
1290 set_bit(tty->read_head, tty->read_flags);
1291 put_tty_queue_nolock(c, tty);
1292 tty->canon_head = tty->read_head;
1294 spin_unlock_irqrestore(&tty->read_lock, flags);
1295 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1296 if (waitqueue_active(&tty->read_wait))
1297 wake_up_interruptible(&tty->read_wait);
1303 finish_erasing(tty);
1304 if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
1305 /* beep if no space */
1306 echo_char_raw('\a', tty);
1307 process_echoes(tty);
1311 echo_char_raw('\n', tty);
1313 /* Record the column of first canon char. */
1314 if (tty->canon_head == tty->read_head)
1315 echo_set_canon_col(tty);
1318 process_echoes(tty);
1321 if (I_PARMRK(tty) && c == (unsigned char) '\377')
1322 put_tty_queue(c, tty);
1324 put_tty_queue(c, tty);
1329 * n_tty_write_wakeup - asynchronous I/O notifier
1332 * Required for the ptys, serial driver etc. since processes
1333 * that attach themselves to the master and rely on ASYNC
1334 * IO must be woken up
1337 static void n_tty_write_wakeup(struct tty_struct *tty)
1339 /* Write out any echoed characters that are still pending */
1340 process_echoes(tty);
1343 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
1344 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1349 * n_tty_receive_buf - data receive
1350 * @tty: terminal device
1353 * @count: characters
1355 * Called by the terminal driver when a block of characters has
1356 * been received. This function must be called from soft contexts
1357 * not from interrupt context. The driver is responsible for making
1358 * calls one at a time and in order (or using flush_to_ldisc)
1361 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1362 char *fp, int count)
1364 const unsigned char *p;
1365 char *f, flags = TTY_NORMAL;
1368 unsigned long cpuflags;
1373 if (tty->real_raw) {
1374 spin_lock_irqsave(&tty->read_lock, cpuflags);
1375 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1376 N_TTY_BUF_SIZE - tty->read_head);
1378 memcpy(tty->read_buf + tty->read_head, cp, i);
1379 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1384 i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1385 N_TTY_BUF_SIZE - tty->read_head);
1387 memcpy(tty->read_buf + tty->read_head, cp, i);
1388 tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1390 spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1392 for (i = count, p = cp, f = fp; i; i--, p++) {
1397 n_tty_receive_char(tty, *p);
1400 n_tty_receive_break(tty);
1404 n_tty_receive_parity_error(tty, *p);
1407 n_tty_receive_overrun(tty);
1410 printk(KERN_ERR "%s: unknown flag %d\n",
1411 tty_name(tty, buf), flags);
1415 if (tty->ops->flush_chars)
1416 tty->ops->flush_chars(tty);
1419 n_tty_set_room(tty);
1421 if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) {
1422 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1423 if (waitqueue_active(&tty->read_wait))
1424 wake_up_interruptible(&tty->read_wait);
1428 * Check the remaining room for the input canonicalization
1429 * mode. We don't want to throttle the driver if we're in
1430 * canonical mode and don't have a newline yet!
1432 if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1436 int is_ignored(int sig)
1438 return (sigismember(¤t->blocked, sig) ||
1439 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1443 * n_tty_set_termios - termios data changed
1445 * @old: previous data
1447 * Called by the tty layer when the user changes termios flags so
1448 * that the line discipline can plan ahead. This function cannot sleep
1449 * and is protected from re-entry by the tty layer. The user is
1450 * guaranteed that this function will not be re-entered or in progress
1451 * when the ldisc is closed.
1453 * Locking: Caller holds tty->termios_mutex
1456 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1458 int canon_change = 1;
1462 canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1464 memset(&tty->read_flags, 0, sizeof tty->read_flags);
1465 tty->canon_head = tty->read_tail;
1466 tty->canon_data = 0;
1470 if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1471 wake_up_interruptible(&tty->read_wait);
1473 tty->icanon = (L_ICANON(tty) != 0);
1474 if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1477 n_tty_set_room(tty);
1480 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1481 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1482 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1484 memset(tty->process_char_map, 0, 256/8);
1486 if (I_IGNCR(tty) || I_ICRNL(tty))
1487 set_bit('\r', tty->process_char_map);
1489 set_bit('\n', tty->process_char_map);
1491 if (L_ICANON(tty)) {
1492 set_bit(ERASE_CHAR(tty), tty->process_char_map);
1493 set_bit(KILL_CHAR(tty), tty->process_char_map);
1494 set_bit(EOF_CHAR(tty), tty->process_char_map);
1495 set_bit('\n', tty->process_char_map);
1496 set_bit(EOL_CHAR(tty), tty->process_char_map);
1497 if (L_IEXTEN(tty)) {
1498 set_bit(WERASE_CHAR(tty),
1499 tty->process_char_map);
1500 set_bit(LNEXT_CHAR(tty),
1501 tty->process_char_map);
1502 set_bit(EOL2_CHAR(tty),
1503 tty->process_char_map);
1505 set_bit(REPRINT_CHAR(tty),
1506 tty->process_char_map);
1510 set_bit(START_CHAR(tty), tty->process_char_map);
1511 set_bit(STOP_CHAR(tty), tty->process_char_map);
1514 set_bit(INTR_CHAR(tty), tty->process_char_map);
1515 set_bit(QUIT_CHAR(tty), tty->process_char_map);
1516 set_bit(SUSP_CHAR(tty), tty->process_char_map);
1518 clear_bit(__DISABLED_CHAR, tty->process_char_map);
1523 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1524 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1525 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1530 n_tty_set_room(tty);
1531 /* The termios change make the tty ready for I/O */
1532 wake_up_interruptible(&tty->write_wait);
1533 wake_up_interruptible(&tty->read_wait);
1537 * n_tty_close - close the ldisc for this tty
1540 * Called from the terminal layer when this line discipline is
1541 * being shut down, either because of a close or becsuse of a
1542 * discipline change. The function will not be called while other
1543 * ldisc methods are in progress.
1546 static void n_tty_close(struct tty_struct *tty)
1548 n_tty_flush_buffer(tty);
1549 if (tty->read_buf) {
1550 free_buf(tty->read_buf);
1551 tty->read_buf = NULL;
1553 if (tty->echo_buf) {
1554 free_buf(tty->echo_buf);
1555 tty->echo_buf = NULL;
1560 * n_tty_open - open an ldisc
1561 * @tty: terminal to open
1563 * Called when this line discipline is being attached to the
1564 * terminal device. Can sleep. Called serialized so that no
1565 * other events will occur in parallel. No further open will occur
1569 static int n_tty_open(struct tty_struct *tty)
1574 /* These are ugly. Currently a malloc failure here can panic */
1575 if (!tty->read_buf) {
1576 tty->read_buf = alloc_buf();
1580 if (!tty->echo_buf) {
1581 tty->echo_buf = alloc_buf();
1585 memset(tty->read_buf, 0, N_TTY_BUF_SIZE);
1586 memset(tty->echo_buf, 0, N_TTY_BUF_SIZE);
1587 reset_buffer_flags(tty);
1589 n_tty_set_termios(tty, NULL);
1590 tty->minimum_to_wake = 1;
1595 static inline int input_available_p(struct tty_struct *tty, int amt)
1598 if (tty->canon_data)
1600 } else if (tty->read_cnt >= (amt ? amt : 1))
1607 * copy_from_read_buf - copy read data directly
1608 * @tty: terminal device
1612 * Helper function to speed up n_tty_read. It is only called when
1613 * ICANON is off; it copies characters straight from the tty queue to
1614 * user space directly. It can be profitably called twice; once to
1615 * drain the space from the tail pointer to the (physical) end of the
1616 * buffer, and once to drain the space from the (physical) beginning of
1617 * the buffer to head pointer.
1619 * Called under the tty->atomic_read_lock sem
1623 static int copy_from_read_buf(struct tty_struct *tty,
1624 unsigned char __user **b,
1630 unsigned long flags;
1633 spin_lock_irqsave(&tty->read_lock, flags);
1634 n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1636 spin_unlock_irqrestore(&tty->read_lock, flags);
1638 retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1640 tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1641 spin_lock_irqsave(&tty->read_lock, flags);
1642 tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1644 spin_unlock_irqrestore(&tty->read_lock, flags);
1651 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1655 * job_control - check job control
1657 * @file: file handle
1659 * Perform job control management checks on this file/tty descriptor
1660 * and if appropriate send any needed signals and return a negative
1661 * error code if action should be taken.
1664 * Locking: None - redirected write test is safe, testing
1665 * current->signal should possibly lock current->sighand
1669 static int job_control(struct tty_struct *tty, struct file *file)
1671 /* Job control check -- must be done at start and after
1672 every sleep (POSIX.1 7.1.1.4). */
1673 /* NOTE: not yet done after every sleep pending a thorough
1674 check of the logic of this change. -- jlc */
1675 /* don't stop on /dev/console */
1676 if (file->f_op->write != redirected_tty_write &&
1677 current->signal->tty == tty) {
1679 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1680 else if (task_pgrp(current) != tty->pgrp) {
1681 if (is_ignored(SIGTTIN) ||
1682 is_current_pgrp_orphaned())
1684 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1685 set_thread_flag(TIF_SIGPENDING);
1686 return -ERESTARTSYS;
1694 * n_tty_read - read function for tty
1696 * @file: file object
1697 * @buf: userspace buffer pointer
1700 * Perform reads for the line discipline. We are guaranteed that the
1701 * line discipline will not be closed under us but we may get multiple
1702 * parallel readers and must handle this ourselves. We may also get
1703 * a hangup. Always called in user context, may sleep.
1705 * This code must be sure never to sleep through a hangup.
1708 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1709 unsigned char __user *buf, size_t nr)
1711 unsigned char __user *b = buf;
1712 DECLARE_WAITQUEUE(wait, current);
1718 unsigned long flags;
1723 BUG_ON(!tty->read_buf);
1725 c = job_control(tty, file);
1730 timeout = MAX_SCHEDULE_TIMEOUT;
1732 time = (HZ / 10) * TIME_CHAR(tty);
1733 minimum = MIN_CHAR(tty);
1736 tty->minimum_to_wake = 1;
1737 else if (!waitqueue_active(&tty->read_wait) ||
1738 (tty->minimum_to_wake > minimum))
1739 tty->minimum_to_wake = minimum;
1746 tty->minimum_to_wake = minimum = 1;
1751 * Internal serialization of reads.
1753 if (file->f_flags & O_NONBLOCK) {
1754 if (!mutex_trylock(&tty->atomic_read_lock))
1757 if (mutex_lock_interruptible(&tty->atomic_read_lock))
1758 return -ERESTARTSYS;
1760 packet = tty->packet;
1762 add_wait_queue(&tty->read_wait, &wait);
1764 /* First test for status change. */
1765 if (packet && tty->link->ctrl_status) {
1769 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1770 cs = tty->link->ctrl_status;
1771 tty->link->ctrl_status = 0;
1772 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1773 if (tty_put_user(tty, cs, b++)) {
1781 /* This statement must be first before checking for input
1782 so that any interrupt will set the state back to
1784 set_current_state(TASK_INTERRUPTIBLE);
1786 if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1787 ((minimum - (b - buf)) >= 1))
1788 tty->minimum_to_wake = (minimum - (b - buf));
1790 if (!input_available_p(tty, 0)) {
1791 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1795 if (tty_hung_up_p(file))
1799 if (file->f_flags & O_NONBLOCK) {
1803 if (signal_pending(current)) {
1804 retval = -ERESTARTSYS;
1807 /* FIXME: does n_tty_set_room need locking ? */
1808 n_tty_set_room(tty);
1809 timeout = schedule_timeout(timeout);
1812 __set_current_state(TASK_RUNNING);
1814 /* Deal with packet mode. */
1815 if (packet && b == buf) {
1816 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1825 /* N.B. avoid overrun if nr == 0 */
1826 while (nr && tty->read_cnt) {
1829 eol = test_and_clear_bit(tty->read_tail,
1831 c = tty->read_buf[tty->read_tail];
1832 spin_lock_irqsave(&tty->read_lock, flags);
1833 tty->read_tail = ((tty->read_tail+1) &
1834 (N_TTY_BUF_SIZE-1));
1837 /* this test should be redundant:
1838 * we shouldn't be reading data if
1841 if (--tty->canon_data < 0)
1842 tty->canon_data = 0;
1844 spin_unlock_irqrestore(&tty->read_lock, flags);
1846 if (!eol || (c != __DISABLED_CHAR)) {
1847 if (tty_put_user(tty, c, b++)) {
1855 tty_audit_push(tty);
1863 /* The copy function takes the read lock and handles
1864 locking internally for this case */
1865 uncopied = copy_from_read_buf(tty, &b, &nr);
1866 uncopied += copy_from_read_buf(tty, &b, &nr);
1873 /* If there is enough space in the read buffer now, let the
1874 * low-level driver know. We use n_tty_chars_in_buffer() to
1875 * check the buffer, as it now knows about canonical mode.
1876 * Otherwise, if the driver is throttled and the line is
1877 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1878 * we won't get any more characters.
1880 if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1881 n_tty_set_room(tty);
1882 check_unthrottle(tty);
1885 if (b - buf >= minimum)
1890 mutex_unlock(&tty->atomic_read_lock);
1891 remove_wait_queue(&tty->read_wait, &wait);
1893 if (!waitqueue_active(&tty->read_wait))
1894 tty->minimum_to_wake = minimum;
1896 __set_current_state(TASK_RUNNING);
1901 clear_bit(TTY_PUSH, &tty->flags);
1902 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1905 n_tty_set_room(tty);
1910 * n_tty_write - write function for tty
1912 * @file: file object
1913 * @buf: userspace buffer pointer
1916 * Write function of the terminal device. This is serialized with
1917 * respect to other write callers but not to termios changes, reads
1918 * and other such events. Since the receive code will echo characters,
1919 * thus calling driver write methods, the output_lock is used in
1920 * the output processing functions called here as well as in the
1921 * echo processing function to protect the column state and space
1922 * left in the buffer.
1924 * This code must be sure never to sleep through a hangup.
1926 * Locking: output_lock to protect column state and space left
1927 * (note that the process_output*() functions take this
1931 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1932 const unsigned char *buf, size_t nr)
1934 const unsigned char *b = buf;
1935 DECLARE_WAITQUEUE(wait, current);
1939 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1940 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1941 retval = tty_check_change(tty);
1946 /* Write out any echoed characters that are still pending */
1947 process_echoes(tty);
1949 add_wait_queue(&tty->write_wait, &wait);
1951 set_current_state(TASK_INTERRUPTIBLE);
1952 if (signal_pending(current)) {
1953 retval = -ERESTARTSYS;
1956 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1960 if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1962 ssize_t num = process_output_block(tty, b, nr);
1974 if (process_output(c, tty) < 0)
1978 if (tty->ops->flush_chars)
1979 tty->ops->flush_chars(tty);
1982 c = tty->ops->write(tty, b, nr);
1995 if (file->f_flags & O_NONBLOCK) {
2002 __set_current_state(TASK_RUNNING);
2003 remove_wait_queue(&tty->write_wait, &wait);
2004 return (b - buf) ? b - buf : retval;
2008 * n_tty_poll - poll method for N_TTY
2009 * @tty: terminal device
2010 * @file: file accessing it
2013 * Called when the line discipline is asked to poll() for data or
2014 * for special events. This code is not serialized with respect to
2015 * other events save open/close.
2017 * This code must be sure never to sleep through a hangup.
2018 * Called without the kernel lock held - fine
2021 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2024 unsigned int mask = 0;
2026 poll_wait(file, &tty->read_wait, wait);
2027 poll_wait(file, &tty->write_wait, wait);
2028 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2029 mask |= POLLIN | POLLRDNORM;
2030 if (tty->packet && tty->link->ctrl_status)
2031 mask |= POLLPRI | POLLIN | POLLRDNORM;
2032 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2034 if (tty_hung_up_p(file))
2036 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2037 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2038 tty->minimum_to_wake = MIN_CHAR(tty);
2040 tty->minimum_to_wake = 1;
2042 if (tty->ops->write && !tty_is_writelocked(tty) &&
2043 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2044 tty_write_room(tty) > 0)
2045 mask |= POLLOUT | POLLWRNORM;
2049 static unsigned long inq_canon(struct tty_struct *tty)
2053 if (!tty->canon_data)
2055 head = tty->canon_head;
2056 tail = tty->read_tail;
2057 nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2058 /* Skip EOF-chars.. */
2059 while (head != tail) {
2060 if (test_bit(tail, tty->read_flags) &&
2061 tty->read_buf[tail] == __DISABLED_CHAR)
2063 tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2068 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2069 unsigned int cmd, unsigned long arg)
2075 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2077 /* FIXME: Locking */
2078 retval = tty->read_cnt;
2080 retval = inq_canon(tty);
2081 return put_user(retval, (unsigned int __user *) arg);
2083 return n_tty_ioctl_helper(tty, file, cmd, arg);
2087 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2088 .magic = TTY_LDISC_MAGIC,
2091 .close = n_tty_close,
2092 .flush_buffer = n_tty_flush_buffer,
2093 .chars_in_buffer = n_tty_chars_in_buffer,
2095 .write = n_tty_write,
2096 .ioctl = n_tty_ioctl,
2097 .set_termios = n_tty_set_termios,
2099 .receive_buf = n_tty_receive_buf,
2100 .write_wakeup = n_tty_write_wakeup