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>
52 #include <linux/ratelimit.h>
53 #include <linux/vmalloc.h>
56 /* number of characters left in xmit buffer before select has we have room */
57 #define WAKEUP_CHARS 256
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
64 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65 #define TTY_THRESHOLD_UNTHROTTLE 128
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
73 #define ECHO_OP_START 0xff
74 #define ECHO_OP_MOVE_BACK_COL 0x80
75 #define ECHO_OP_SET_CANON_COL 0x81
76 #define ECHO_OP_ERASE_TAB 0x82
78 #define ECHO_COMMIT_WATERMARK 256
79 #define ECHO_BLOCK 256
80 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
85 # define n_tty_trace(f, args...) trace_printk(f, ##args)
87 # define n_tty_trace(f, args...)
91 /* producer-published */
98 DECLARE_BITMAP(char_map, 256);
100 /* private to n_tty_receive_overrun (single-threaded) */
101 unsigned long overrun_time;
107 /* must hold exclusive termios_rwsem to reset these */
108 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
109 unsigned char push:1;
111 /* shared by producer and consumer */
112 char read_buf[N_TTY_BUF_SIZE];
113 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
114 unsigned char echo_buf[N_TTY_BUF_SIZE];
118 /* consumer-published */
122 /* protected by output lock */
124 unsigned int canon_column;
127 struct mutex atomic_read_lock;
128 struct mutex output_lock;
131 static inline size_t read_cnt(struct n_tty_data *ldata)
133 return ldata->read_head - ldata->read_tail;
136 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
138 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
141 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
143 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
146 static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
148 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
151 static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
153 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
156 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
157 unsigned char __user *ptr)
159 struct n_tty_data *ldata = tty->disc_data;
161 tty_audit_add_data(tty, &x, 1, ldata->icanon);
162 return put_user(x, ptr);
166 * n_tty_kick_worker - start input worker (if required)
169 * Re-schedules the flip buffer work if it may have stopped
171 * Caller holds exclusive termios_rwsem
173 * n_tty_read()/consumer path:
174 * holds non-exclusive termios_rwsem
177 static void n_tty_kick_worker(struct tty_struct *tty)
179 struct n_tty_data *ldata = tty->disc_data;
181 /* Did the input worker stop? Restart it */
182 if (unlikely(ldata->no_room)) {
185 WARN_RATELIMIT(tty->port->itty == NULL,
186 "scheduling with invalid itty\n");
187 /* see if ldisc has been killed - if so, this means that
188 * even though the ldisc has been halted and ->buf.work
189 * cancelled, ->buf.work is about to be rescheduled
191 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
192 "scheduling buffer work for halted ldisc\n");
193 queue_work(system_unbound_wq, &tty->port->buf.work);
197 static ssize_t chars_in_buffer(struct tty_struct *tty)
199 struct n_tty_data *ldata = tty->disc_data;
203 n = ldata->commit_head - ldata->read_tail;
205 n = ldata->canon_head - ldata->read_tail;
210 * n_tty_write_wakeup - asynchronous I/O notifier
213 * Required for the ptys, serial driver etc. since processes
214 * that attach themselves to the master and rely on ASYNC
215 * IO must be woken up
218 static void n_tty_write_wakeup(struct tty_struct *tty)
220 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
221 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
224 static void n_tty_check_throttle(struct tty_struct *tty)
226 struct n_tty_data *ldata = tty->disc_data;
228 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
231 * Check the remaining room for the input canonicalization
232 * mode. We don't want to throttle the driver if we're in
233 * canonical mode and don't have a newline yet!
235 if (ldata->icanon && ldata->canon_head == ldata->read_tail)
240 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
241 if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
243 throttled = tty_throttle_safe(tty);
247 __tty_set_flow_change(tty, 0);
250 static void n_tty_check_unthrottle(struct tty_struct *tty)
252 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
253 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
254 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
258 n_tty_kick_worker(tty);
259 n_tty_write_wakeup(tty->link);
260 if (waitqueue_active(&tty->link->write_wait))
261 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
265 /* If there is enough space in the read buffer now, let the
266 * low-level driver know. We use chars_in_buffer() to
267 * check the buffer, as it now knows about canonical mode.
268 * Otherwise, if the driver is throttled and the line is
269 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
270 * we won't get any more characters.
275 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
276 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
280 n_tty_kick_worker(tty);
281 unthrottled = tty_unthrottle_safe(tty);
285 __tty_set_flow_change(tty, 0);
289 * put_tty_queue - add character to tty
293 * Add a character to the tty read_buf queue.
295 * n_tty_receive_buf()/producer path:
296 * caller holds non-exclusive termios_rwsem
299 static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
301 *read_buf_addr(ldata, ldata->read_head) = c;
306 * reset_buffer_flags - reset buffer state
307 * @tty: terminal to reset
309 * Reset the read buffer counters and clear the flags.
310 * Called from n_tty_open() and n_tty_flush_buffer().
312 * Locking: caller holds exclusive termios_rwsem
313 * (or locking is not required)
316 static void reset_buffer_flags(struct n_tty_data *ldata)
318 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
319 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
320 ldata->commit_head = 0;
321 ldata->echo_mark = 0;
322 ldata->line_start = 0;
325 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
329 static void n_tty_packet_mode_flush(struct tty_struct *tty)
333 if (tty->link->packet) {
334 spin_lock_irqsave(&tty->ctrl_lock, flags);
335 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
336 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
337 if (waitqueue_active(&tty->link->read_wait))
338 wake_up_interruptible(&tty->link->read_wait);
343 * n_tty_flush_buffer - clean input queue
344 * @tty: terminal device
346 * Flush the input buffer. Called when the tty layer wants the
347 * buffer flushed (eg at hangup) or when the N_TTY line discipline
348 * internally has to clean the pending queue (for example some signals).
350 * Holds termios_rwsem to exclude producer/consumer while
351 * buffer indices are reset.
353 * Locking: ctrl_lock, exclusive termios_rwsem
356 static void n_tty_flush_buffer(struct tty_struct *tty)
358 down_write(&tty->termios_rwsem);
359 reset_buffer_flags(tty->disc_data);
360 n_tty_kick_worker(tty);
363 n_tty_packet_mode_flush(tty);
364 up_write(&tty->termios_rwsem);
368 * n_tty_chars_in_buffer - report available bytes
371 * Report the number of characters buffered to be delivered to user
372 * at this instant in time.
374 * Locking: exclusive termios_rwsem
377 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
381 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
383 down_write(&tty->termios_rwsem);
384 n = chars_in_buffer(tty);
385 up_write(&tty->termios_rwsem);
390 * is_utf8_continuation - utf8 multibyte check
393 * Returns true if the utf8 character 'c' is a multibyte continuation
394 * character. We use this to correctly compute the on screen size
395 * of the character when printing
398 static inline int is_utf8_continuation(unsigned char c)
400 return (c & 0xc0) == 0x80;
404 * is_continuation - multibyte check
407 * Returns true if the utf8 character 'c' is a multibyte continuation
408 * character and the terminal is in unicode mode.
411 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
413 return I_IUTF8(tty) && is_utf8_continuation(c);
417 * do_output_char - output one character
418 * @c: character (or partial unicode symbol)
419 * @tty: terminal device
420 * @space: space available in tty driver write buffer
422 * This is a helper function that handles one output character
423 * (including special characters like TAB, CR, LF, etc.),
424 * doing OPOST processing and putting the results in the
425 * tty driver's write buffer.
427 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
428 * and NLDLY. They simply aren't relevant in the world today.
429 * If you ever need them, add them here.
431 * Returns the number of bytes of buffer space used or -1 if
434 * Locking: should be called under the output_lock to protect
435 * the column state and space left in the buffer
438 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
440 struct n_tty_data *ldata = tty->disc_data;
453 ldata->canon_column = ldata->column = 0;
454 tty->ops->write(tty, "\r\n", 2);
457 ldata->canon_column = ldata->column;
460 if (O_ONOCR(tty) && ldata->column == 0)
465 ldata->canon_column = ldata->column = 0;
468 ldata->canon_column = ldata->column = 0;
471 spaces = 8 - (ldata->column & 7);
472 if (O_TABDLY(tty) == XTABS) {
475 ldata->column += spaces;
476 tty->ops->write(tty, " ", spaces);
479 ldata->column += spaces;
482 if (ldata->column > 0)
489 if (!is_continuation(c, tty))
495 tty_put_char(tty, c);
500 * process_output - output post processor
501 * @c: character (or partial unicode symbol)
502 * @tty: terminal device
504 * Output one character with OPOST processing.
505 * Returns -1 when the output device is full and the character
508 * Locking: output_lock to protect column state and space left
509 * (also, this is called from n_tty_write under the
510 * tty layer write lock)
513 static int process_output(unsigned char c, struct tty_struct *tty)
515 struct n_tty_data *ldata = tty->disc_data;
518 mutex_lock(&ldata->output_lock);
520 space = tty_write_room(tty);
521 retval = do_output_char(c, tty, space);
523 mutex_unlock(&ldata->output_lock);
531 * process_output_block - block post processor
532 * @tty: terminal device
533 * @buf: character buffer
534 * @nr: number of bytes to output
536 * Output a block of characters with OPOST processing.
537 * Returns the number of characters output.
539 * This path is used to speed up block console writes, among other
540 * things when processing blocks of output data. It handles only
541 * the simple cases normally found and helps to generate blocks of
542 * symbols for the console driver and thus improve performance.
544 * Locking: output_lock to protect column state and space left
545 * (also, this is called from n_tty_write under the
546 * tty layer write lock)
549 static ssize_t process_output_block(struct tty_struct *tty,
550 const unsigned char *buf, unsigned int nr)
552 struct n_tty_data *ldata = tty->disc_data;
555 const unsigned char *cp;
557 mutex_lock(&ldata->output_lock);
559 space = tty_write_room(tty);
561 mutex_unlock(&ldata->output_lock);
567 for (i = 0, cp = buf; i < nr; i++, cp++) {
568 unsigned char c = *cp;
576 ldata->canon_column = ldata->column;
579 if (O_ONOCR(tty) && ldata->column == 0)
583 ldata->canon_column = ldata->column = 0;
588 if (ldata->column > 0)
595 if (!is_continuation(c, tty))
602 i = tty->ops->write(tty, buf, i);
604 mutex_unlock(&ldata->output_lock);
609 * process_echoes - write pending echo characters
610 * @tty: terminal device
612 * Write previously buffered echo (and other ldisc-generated)
613 * characters to the tty.
615 * Characters generated by the ldisc (including echoes) need to
616 * be buffered because the driver's write buffer can fill during
617 * heavy program output. Echoing straight to the driver will
618 * often fail under these conditions, causing lost characters and
619 * resulting mismatches of ldisc state information.
621 * Since the ldisc state must represent the characters actually sent
622 * to the driver at the time of the write, operations like certain
623 * changes in column state are also saved in the buffer and executed
626 * A circular fifo buffer is used so that the most recent characters
627 * are prioritized. Also, when control characters are echoed with a
628 * prefixed "^", the pair is treated atomically and thus not separated.
630 * Locking: callers must hold output_lock
633 static size_t __process_echoes(struct tty_struct *tty)
635 struct n_tty_data *ldata = tty->disc_data;
636 int space, old_space;
640 old_space = space = tty_write_room(tty);
642 tail = ldata->echo_tail;
643 while (ldata->echo_commit != tail) {
644 c = echo_buf(ldata, tail);
645 if (c == ECHO_OP_START) {
647 int no_space_left = 0;
650 * If the buffer byte is the start of a multi-byte
651 * operation, get the next byte, which is either the
652 * op code or a control character value.
654 op = echo_buf(ldata, tail + 1);
657 unsigned int num_chars, num_bs;
659 case ECHO_OP_ERASE_TAB:
660 num_chars = echo_buf(ldata, tail + 2);
663 * Determine how many columns to go back
664 * in order to erase the tab.
665 * This depends on the number of columns
666 * used by other characters within the tab
667 * area. If this (modulo 8) count is from
668 * the start of input rather than from a
669 * previous tab, we offset by canon column.
670 * Otherwise, tab spacing is normal.
672 if (!(num_chars & 0x80))
673 num_chars += ldata->canon_column;
674 num_bs = 8 - (num_chars & 7);
676 if (num_bs > space) {
682 tty_put_char(tty, '\b');
683 if (ldata->column > 0)
689 case ECHO_OP_SET_CANON_COL:
690 ldata->canon_column = ldata->column;
694 case ECHO_OP_MOVE_BACK_COL:
695 if (ldata->column > 0)
701 /* This is an escaped echo op start code */
706 tty_put_char(tty, ECHO_OP_START);
714 * If the op is not a special byte code,
715 * it is a ctrl char tagged to be echoed
716 * as "^X" (where X is the letter
717 * representing the control char).
718 * Note that we must ensure there is
719 * enough space for the whole ctrl pair.
726 tty_put_char(tty, '^');
727 tty_put_char(tty, op ^ 0100);
737 int retval = do_output_char(c, tty, space);
744 tty_put_char(tty, c);
751 /* If the echo buffer is nearly full (so that the possibility exists
752 * of echo overrun before the next commit), then discard enough
753 * data at the tail to prevent a subsequent overrun */
754 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
755 if (echo_buf(ldata, tail) == ECHO_OP_START) {
756 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
764 ldata->echo_tail = tail;
765 return old_space - space;
768 static void commit_echoes(struct tty_struct *tty)
770 struct n_tty_data *ldata = tty->disc_data;
771 size_t nr, old, echoed;
774 head = ldata->echo_head;
775 ldata->echo_mark = head;
776 old = ldata->echo_commit - ldata->echo_tail;
778 /* Process committed echoes if the accumulated # of bytes
779 * is over the threshold (and try again each time another
780 * block is accumulated) */
781 nr = head - ldata->echo_tail;
782 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
785 mutex_lock(&ldata->output_lock);
786 ldata->echo_commit = head;
787 echoed = __process_echoes(tty);
788 mutex_unlock(&ldata->output_lock);
790 if (echoed && tty->ops->flush_chars)
791 tty->ops->flush_chars(tty);
794 static void process_echoes(struct tty_struct *tty)
796 struct n_tty_data *ldata = tty->disc_data;
799 if (ldata->echo_mark == ldata->echo_tail)
802 mutex_lock(&ldata->output_lock);
803 ldata->echo_commit = ldata->echo_mark;
804 echoed = __process_echoes(tty);
805 mutex_unlock(&ldata->output_lock);
807 if (echoed && tty->ops->flush_chars)
808 tty->ops->flush_chars(tty);
811 /* NB: echo_mark and echo_head should be equivalent here */
812 static void flush_echoes(struct tty_struct *tty)
814 struct n_tty_data *ldata = tty->disc_data;
816 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
817 ldata->echo_commit == ldata->echo_head)
820 mutex_lock(&ldata->output_lock);
821 ldata->echo_commit = ldata->echo_head;
822 __process_echoes(tty);
823 mutex_unlock(&ldata->output_lock);
827 * add_echo_byte - add a byte to the echo buffer
828 * @c: unicode byte to echo
831 * Add a character or operation byte to the echo buffer.
834 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
836 *echo_buf_addr(ldata, ldata->echo_head++) = c;
840 * echo_move_back_col - add operation to move back a column
843 * Add an operation to the echo buffer to move back one column.
846 static void echo_move_back_col(struct n_tty_data *ldata)
848 add_echo_byte(ECHO_OP_START, ldata);
849 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
853 * echo_set_canon_col - add operation to set the canon column
856 * Add an operation to the echo buffer to set the canon column
857 * to the current column.
860 static void echo_set_canon_col(struct n_tty_data *ldata)
862 add_echo_byte(ECHO_OP_START, ldata);
863 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
867 * echo_erase_tab - add operation to erase a tab
868 * @num_chars: number of character columns already used
869 * @after_tab: true if num_chars starts after a previous tab
872 * Add an operation to the echo buffer to erase a tab.
874 * Called by the eraser function, which knows how many character
875 * columns have been used since either a previous tab or the start
876 * of input. This information will be used later, along with
877 * canon column (if applicable), to go back the correct number
881 static void echo_erase_tab(unsigned int num_chars, int after_tab,
882 struct n_tty_data *ldata)
884 add_echo_byte(ECHO_OP_START, ldata);
885 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
887 /* We only need to know this modulo 8 (tab spacing) */
890 /* Set the high bit as a flag if num_chars is after a previous tab */
894 add_echo_byte(num_chars, ldata);
898 * echo_char_raw - echo a character raw
899 * @c: unicode byte to echo
900 * @tty: terminal device
902 * Echo user input back onto the screen. This must be called only when
903 * L_ECHO(tty) is true. Called from the driver receive_buf path.
905 * This variant does not treat control characters specially.
908 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
910 if (c == ECHO_OP_START) {
911 add_echo_byte(ECHO_OP_START, ldata);
912 add_echo_byte(ECHO_OP_START, ldata);
914 add_echo_byte(c, ldata);
919 * echo_char - echo a character
920 * @c: unicode byte to echo
921 * @tty: terminal device
923 * Echo user input back onto the screen. This must be called only when
924 * L_ECHO(tty) is true. Called from the driver receive_buf path.
926 * This variant tags control characters to be echoed as "^X"
927 * (where X is the letter representing the control char).
930 static void echo_char(unsigned char c, struct tty_struct *tty)
932 struct n_tty_data *ldata = tty->disc_data;
934 if (c == ECHO_OP_START) {
935 add_echo_byte(ECHO_OP_START, ldata);
936 add_echo_byte(ECHO_OP_START, ldata);
938 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
939 add_echo_byte(ECHO_OP_START, ldata);
940 add_echo_byte(c, ldata);
945 * finish_erasing - complete erase
949 static inline void finish_erasing(struct n_tty_data *ldata)
951 if (ldata->erasing) {
952 echo_char_raw('/', ldata);
958 * eraser - handle erase function
959 * @c: character input
960 * @tty: terminal device
962 * Perform erase and necessary output when an erase character is
963 * present in the stream from the driver layer. Handles the complexities
964 * of UTF-8 multibyte symbols.
966 * n_tty_receive_buf()/producer path:
967 * caller holds non-exclusive termios_rwsem
970 static void eraser(unsigned char c, struct tty_struct *tty)
972 struct n_tty_data *ldata = tty->disc_data;
973 enum { ERASE, WERASE, KILL } kill_type;
978 if (ldata->read_head == ldata->canon_head) {
979 /* process_output('\a', tty); */ /* what do you think? */
982 if (c == ERASE_CHAR(tty))
984 else if (c == WERASE_CHAR(tty))
988 ldata->read_head = ldata->canon_head;
991 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
992 ldata->read_head = ldata->canon_head;
993 finish_erasing(ldata);
994 echo_char(KILL_CHAR(tty), tty);
995 /* Add a newline if ECHOK is on and ECHOKE is off. */
997 echo_char_raw('\n', ldata);
1004 while (ldata->read_head != ldata->canon_head) {
1005 head = ldata->read_head;
1007 /* erase a single possibly multibyte character */
1010 c = read_buf(ldata, head);
1011 } while (is_continuation(c, tty) && head != ldata->canon_head);
1013 /* do not partially erase */
1014 if (is_continuation(c, tty))
1017 if (kill_type == WERASE) {
1018 /* Equivalent to BSD's ALTWERASE. */
1019 if (isalnum(c) || c == '_')
1021 else if (seen_alnums)
1024 cnt = ldata->read_head - head;
1025 ldata->read_head = head;
1027 if (L_ECHOPRT(tty)) {
1028 if (!ldata->erasing) {
1029 echo_char_raw('\\', ldata);
1032 /* if cnt > 1, output a multi-byte character */
1036 echo_char_raw(read_buf(ldata, head), ldata);
1037 echo_move_back_col(ldata);
1039 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1040 echo_char(ERASE_CHAR(tty), tty);
1041 } else if (c == '\t') {
1042 unsigned int num_chars = 0;
1044 size_t tail = ldata->read_head;
1047 * Count the columns used for characters
1048 * since the start of input or after a
1050 * This info is used to go back the correct
1051 * number of columns.
1053 while (tail != ldata->canon_head) {
1055 c = read_buf(ldata, tail);
1059 } else if (iscntrl(c)) {
1062 } else if (!is_continuation(c, tty)) {
1066 echo_erase_tab(num_chars, after_tab, ldata);
1068 if (iscntrl(c) && L_ECHOCTL(tty)) {
1069 echo_char_raw('\b', ldata);
1070 echo_char_raw(' ', ldata);
1071 echo_char_raw('\b', ldata);
1073 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1074 echo_char_raw('\b', ldata);
1075 echo_char_raw(' ', ldata);
1076 echo_char_raw('\b', ldata);
1080 if (kill_type == ERASE)
1083 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1084 finish_erasing(ldata);
1088 * isig - handle the ISIG optio
1092 * Called when a signal is being sent due to terminal input.
1093 * Called from the driver receive_buf path so serialized.
1095 * Locking: ctrl_lock
1098 static void isig(int sig, struct tty_struct *tty)
1100 struct pid *tty_pgrp = tty_get_pgrp(tty);
1102 kill_pgrp(tty_pgrp, sig, 1);
1108 * n_tty_receive_break - handle break
1111 * An RS232 break event has been hit in the incoming bitstream. This
1112 * can cause a variety of events depending upon the termios settings.
1114 * n_tty_receive_buf()/producer path:
1115 * caller holds non-exclusive termios_rwsem
1117 * Note: may get exclusive termios_rwsem if flushing input buffer
1120 static void n_tty_receive_break(struct tty_struct *tty)
1122 struct n_tty_data *ldata = tty->disc_data;
1126 if (I_BRKINT(tty)) {
1128 if (!L_NOFLSH(tty)) {
1129 /* flushing needs exclusive termios_rwsem */
1130 up_read(&tty->termios_rwsem);
1131 n_tty_flush_buffer(tty);
1132 tty_driver_flush_buffer(tty);
1133 down_read(&tty->termios_rwsem);
1137 if (I_PARMRK(tty)) {
1138 put_tty_queue('\377', ldata);
1139 put_tty_queue('\0', ldata);
1141 put_tty_queue('\0', ldata);
1142 if (waitqueue_active(&tty->read_wait))
1143 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1147 * n_tty_receive_overrun - handle overrun reporting
1150 * Data arrived faster than we could process it. While the tty
1151 * driver has flagged this the bits that were missed are gone
1154 * Called from the receive_buf path so single threaded. Does not
1155 * need locking as num_overrun and overrun_time are function
1159 static void n_tty_receive_overrun(struct tty_struct *tty)
1161 struct n_tty_data *ldata = tty->disc_data;
1164 ldata->num_overrun++;
1165 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1166 time_after(ldata->overrun_time, jiffies)) {
1167 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1169 ldata->num_overrun);
1170 ldata->overrun_time = jiffies;
1171 ldata->num_overrun = 0;
1176 * n_tty_receive_parity_error - error notifier
1177 * @tty: terminal device
1180 * Process a parity error and queue the right data to indicate
1181 * the error case if necessary.
1183 * n_tty_receive_buf()/producer path:
1184 * caller holds non-exclusive termios_rwsem
1186 static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1188 struct n_tty_data *ldata = tty->disc_data;
1193 if (I_PARMRK(tty)) {
1194 put_tty_queue('\377', ldata);
1195 put_tty_queue('\0', ldata);
1196 put_tty_queue(c, ldata);
1198 put_tty_queue('\0', ldata);
1200 put_tty_queue(c, ldata);
1201 if (waitqueue_active(&tty->read_wait))
1202 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1206 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1208 if (!L_NOFLSH(tty)) {
1209 /* flushing needs exclusive termios_rwsem */
1210 up_read(&tty->termios_rwsem);
1211 n_tty_flush_buffer(tty);
1212 tty_driver_flush_buffer(tty);
1213 down_read(&tty->termios_rwsem);
1221 process_echoes(tty);
1227 * n_tty_receive_char - perform processing
1228 * @tty: terminal device
1231 * Process an individual character of input received from the driver.
1232 * This is serialized with respect to itself by the rules for the
1235 * n_tty_receive_buf()/producer path:
1236 * caller holds non-exclusive termios_rwsem
1237 * publishes canon_head if canonical mode is active
1239 * Returns 1 if LNEXT was received, else returns 0
1243 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1245 struct n_tty_data *ldata = tty->disc_data;
1248 if (c == START_CHAR(tty)) {
1250 process_echoes(tty);
1253 if (c == STOP_CHAR(tty)) {
1260 if (c == INTR_CHAR(tty)) {
1261 n_tty_receive_signal_char(tty, SIGINT, c);
1263 } else if (c == QUIT_CHAR(tty)) {
1264 n_tty_receive_signal_char(tty, SIGQUIT, c);
1266 } else if (c == SUSP_CHAR(tty)) {
1267 n_tty_receive_signal_char(tty, SIGTSTP, c);
1272 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1274 process_echoes(tty);
1282 } else if (c == '\n' && I_INLCR(tty))
1285 if (ldata->icanon) {
1286 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1287 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1292 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1295 finish_erasing(ldata);
1296 if (L_ECHOCTL(tty)) {
1297 echo_char_raw('^', ldata);
1298 echo_char_raw('\b', ldata);
1304 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1305 size_t tail = ldata->canon_head;
1307 finish_erasing(ldata);
1309 echo_char_raw('\n', ldata);
1310 while (tail != ldata->read_head) {
1311 echo_char(read_buf(ldata, tail), tty);
1318 if (L_ECHO(tty) || L_ECHONL(tty)) {
1319 echo_char_raw('\n', ldata);
1322 goto handle_newline;
1324 if (c == EOF_CHAR(tty)) {
1325 c = __DISABLED_CHAR;
1326 goto handle_newline;
1328 if ((c == EOL_CHAR(tty)) ||
1329 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1331 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1334 /* Record the column of first canon char. */
1335 if (ldata->canon_head == ldata->read_head)
1336 echo_set_canon_col(ldata);
1341 * XXX does PARMRK doubling happen for
1342 * EOL_CHAR and EOL2_CHAR?
1344 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1345 put_tty_queue(c, ldata);
1348 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1349 put_tty_queue(c, ldata);
1350 smp_store_release(&ldata->canon_head, ldata->read_head);
1351 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1352 if (waitqueue_active(&tty->read_wait))
1353 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1359 finish_erasing(ldata);
1361 echo_char_raw('\n', ldata);
1363 /* Record the column of first canon char. */
1364 if (ldata->canon_head == ldata->read_head)
1365 echo_set_canon_col(ldata);
1371 /* PARMRK doubling check */
1372 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1373 put_tty_queue(c, ldata);
1375 put_tty_queue(c, ldata);
1380 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1382 struct n_tty_data *ldata = tty->disc_data;
1384 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1386 process_echoes(tty);
1389 finish_erasing(ldata);
1390 /* Record the column of first canon char. */
1391 if (ldata->canon_head == ldata->read_head)
1392 echo_set_canon_col(ldata);
1396 /* PARMRK doubling check */
1397 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1398 put_tty_queue(c, ldata);
1399 put_tty_queue(c, ldata);
1402 static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1404 n_tty_receive_char_inline(tty, c);
1408 n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1410 struct n_tty_data *ldata = tty->disc_data;
1412 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1414 process_echoes(tty);
1417 finish_erasing(ldata);
1418 /* Record the column of first canon char. */
1419 if (ldata->canon_head == ldata->read_head)
1420 echo_set_canon_col(ldata);
1424 put_tty_queue(c, ldata);
1427 static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1431 if (I_IUCLC(tty) && L_IEXTEN(tty))
1435 if (c == STOP_CHAR(tty))
1437 else if (c == START_CHAR(tty) ||
1438 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1439 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1440 c != SUSP_CHAR(tty))) {
1442 process_echoes(tty);
1448 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1454 n_tty_receive_break(tty);
1458 n_tty_receive_parity_error(tty, c);
1461 n_tty_receive_overrun(tty);
1464 printk(KERN_ERR "%s: unknown flag %d\n",
1465 tty_name(tty, buf), flag);
1471 n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1473 struct n_tty_data *ldata = tty->disc_data;
1476 if (likely(flag == TTY_NORMAL)) {
1479 if (I_IUCLC(tty) && L_IEXTEN(tty))
1481 n_tty_receive_char(tty, c);
1483 n_tty_receive_char_flagged(tty, c, flag);
1487 * n_tty_receive_buf - data receive
1488 * @tty: terminal device
1491 * @count: characters
1493 * Called by the terminal driver when a block of characters has
1494 * been received. This function must be called from soft contexts
1495 * not from interrupt context. The driver is responsible for making
1496 * calls one at a time and in order (or using flush_to_ldisc)
1498 * n_tty_receive_buf()/producer path:
1499 * claims non-exclusive termios_rwsem
1500 * publishes commit_head or canon_head
1504 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1505 char *fp, int count)
1507 struct n_tty_data *ldata = tty->disc_data;
1510 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1511 n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
1512 memcpy(read_buf_addr(ldata, head), cp, n);
1513 ldata->read_head += n;
1517 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1518 n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
1519 memcpy(read_buf_addr(ldata, head), cp, n);
1520 ldata->read_head += n;
1524 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1525 char *fp, int count)
1527 struct n_tty_data *ldata = tty->disc_data;
1528 char flag = TTY_NORMAL;
1533 if (likely(flag == TTY_NORMAL))
1534 put_tty_queue(*cp++, ldata);
1536 n_tty_receive_char_flagged(tty, *cp++, flag);
1541 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1542 char *fp, int count)
1544 char flag = TTY_NORMAL;
1549 if (likely(flag == TTY_NORMAL))
1550 n_tty_receive_char_closing(tty, *cp++);
1552 n_tty_receive_char_flagged(tty, *cp++, flag);
1557 n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1558 char *fp, int count)
1560 struct n_tty_data *ldata = tty->disc_data;
1561 char flag = TTY_NORMAL;
1566 if (likely(flag == TTY_NORMAL)) {
1567 unsigned char c = *cp++;
1571 if (I_IUCLC(tty) && L_IEXTEN(tty))
1573 if (L_EXTPROC(tty)) {
1574 put_tty_queue(c, ldata);
1577 if (!test_bit(c, ldata->char_map))
1578 n_tty_receive_char_inline(tty, c);
1579 else if (n_tty_receive_char_special(tty, c) && count) {
1582 n_tty_receive_char_lnext(tty, *cp++, flag);
1586 n_tty_receive_char_flagged(tty, *cp++, flag);
1591 n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1592 char *fp, int count)
1594 struct n_tty_data *ldata = tty->disc_data;
1595 char flag = TTY_NORMAL;
1600 if (likely(flag == TTY_NORMAL)) {
1601 unsigned char c = *cp++;
1603 if (!test_bit(c, ldata->char_map))
1604 n_tty_receive_char_fast(tty, c);
1605 else if (n_tty_receive_char_special(tty, c) && count) {
1608 n_tty_receive_char_lnext(tty, *cp++, flag);
1612 n_tty_receive_char_flagged(tty, *cp++, flag);
1616 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1617 char *fp, int count)
1619 struct n_tty_data *ldata = tty->disc_data;
1620 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1622 if (ldata->real_raw)
1623 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1624 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1625 n_tty_receive_buf_raw(tty, cp, fp, count);
1626 else if (tty->closing && !L_EXTPROC(tty))
1627 n_tty_receive_buf_closing(tty, cp, fp, count);
1630 char flag = TTY_NORMAL;
1634 n_tty_receive_char_lnext(tty, *cp++, flag);
1638 if (!preops && !I_PARMRK(tty))
1639 n_tty_receive_buf_fast(tty, cp, fp, count);
1641 n_tty_receive_buf_standard(tty, cp, fp, count);
1644 if (tty->ops->flush_chars)
1645 tty->ops->flush_chars(tty);
1648 if (ldata->icanon && !L_EXTPROC(tty))
1651 /* publish read_head to consumer */
1652 smp_store_release(&ldata->commit_head, ldata->read_head);
1654 if ((read_cnt(ldata) >= ldata->minimum_to_wake) || L_EXTPROC(tty)) {
1655 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1656 if (waitqueue_active(&tty->read_wait))
1657 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1662 n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1663 char *fp, int count, int flow)
1665 struct n_tty_data *ldata = tty->disc_data;
1666 int room, n, rcvd = 0;
1668 down_read(&tty->termios_rwsem);
1672 * When PARMRK is set, each input char may take up to 3 chars
1673 * in the read buf; reduce the buffer space avail by 3x
1675 * If we are doing input canonicalization, and there are no
1676 * pending newlines, let characters through without limit, so
1677 * that erase characters will be handled. Other excess
1678 * characters will be beeped.
1680 * paired with store in *_copy_from_read_buf() -- guarantees
1681 * the consumer has loaded the data in read_buf up to the new
1682 * read_tail (so this producer will not overwrite unread data)
1684 size_t tail = smp_load_acquire(&ldata->read_tail);
1686 room = N_TTY_BUF_SIZE - (ldata->read_head - tail) - 1;
1690 room = ldata->icanon && ldata->canon_head == tail;
1692 n = min(count, room);
1698 __receive_buf(tty, cp, fp, n);
1706 tty->receive_room = room;
1707 n_tty_check_throttle(tty);
1708 up_read(&tty->termios_rwsem);
1713 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1714 char *fp, int count)
1716 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1719 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1720 char *fp, int count)
1722 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1725 int is_ignored(int sig)
1727 return (sigismember(¤t->blocked, sig) ||
1728 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1732 * n_tty_set_termios - termios data changed
1734 * @old: previous data
1736 * Called by the tty layer when the user changes termios flags so
1737 * that the line discipline can plan ahead. This function cannot sleep
1738 * and is protected from re-entry by the tty layer. The user is
1739 * guaranteed that this function will not be re-entered or in progress
1740 * when the ldisc is closed.
1742 * Locking: Caller holds tty->termios_rwsem
1745 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1747 struct n_tty_data *ldata = tty->disc_data;
1749 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1750 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1751 ldata->line_start = ldata->read_tail;
1752 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1753 ldata->canon_head = ldata->read_tail;
1756 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1758 ldata->canon_head = ldata->read_head;
1761 ldata->commit_head = ldata->read_head;
1766 ldata->icanon = (L_ICANON(tty) != 0);
1768 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1769 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1770 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1772 bitmap_zero(ldata->char_map, 256);
1774 if (I_IGNCR(tty) || I_ICRNL(tty))
1775 set_bit('\r', ldata->char_map);
1777 set_bit('\n', ldata->char_map);
1779 if (L_ICANON(tty)) {
1780 set_bit(ERASE_CHAR(tty), ldata->char_map);
1781 set_bit(KILL_CHAR(tty), ldata->char_map);
1782 set_bit(EOF_CHAR(tty), ldata->char_map);
1783 set_bit('\n', ldata->char_map);
1784 set_bit(EOL_CHAR(tty), ldata->char_map);
1785 if (L_IEXTEN(tty)) {
1786 set_bit(WERASE_CHAR(tty), ldata->char_map);
1787 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1788 set_bit(EOL2_CHAR(tty), ldata->char_map);
1790 set_bit(REPRINT_CHAR(tty),
1795 set_bit(START_CHAR(tty), ldata->char_map);
1796 set_bit(STOP_CHAR(tty), ldata->char_map);
1799 set_bit(INTR_CHAR(tty), ldata->char_map);
1800 set_bit(QUIT_CHAR(tty), ldata->char_map);
1801 set_bit(SUSP_CHAR(tty), ldata->char_map);
1803 clear_bit(__DISABLED_CHAR, ldata->char_map);
1805 ldata->real_raw = 0;
1808 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1809 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1810 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1811 ldata->real_raw = 1;
1813 ldata->real_raw = 0;
1816 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1817 * been stopped by STOP_CHAR(tty) before it.
1819 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1821 process_echoes(tty);
1824 /* The termios change make the tty ready for I/O */
1825 if (waitqueue_active(&tty->write_wait))
1826 wake_up_interruptible(&tty->write_wait);
1827 if (waitqueue_active(&tty->read_wait))
1828 wake_up_interruptible(&tty->read_wait);
1832 * n_tty_close - close the ldisc for this tty
1835 * Called from the terminal layer when this line discipline is
1836 * being shut down, either because of a close or becsuse of a
1837 * discipline change. The function will not be called while other
1838 * ldisc methods are in progress.
1841 static void n_tty_close(struct tty_struct *tty)
1843 struct n_tty_data *ldata = tty->disc_data;
1846 n_tty_packet_mode_flush(tty);
1849 tty->disc_data = NULL;
1853 * n_tty_open - open an ldisc
1854 * @tty: terminal to open
1856 * Called when this line discipline is being attached to the
1857 * terminal device. Can sleep. Called serialized so that no
1858 * other events will occur in parallel. No further open will occur
1862 static int n_tty_open(struct tty_struct *tty)
1864 struct n_tty_data *ldata;
1866 /* Currently a malloc failure here can panic */
1867 ldata = vmalloc(sizeof(*ldata));
1871 ldata->overrun_time = jiffies;
1872 mutex_init(&ldata->atomic_read_lock);
1873 mutex_init(&ldata->output_lock);
1875 tty->disc_data = ldata;
1876 reset_buffer_flags(tty->disc_data);
1878 ldata->canon_column = 0;
1879 ldata->minimum_to_wake = 1;
1880 ldata->num_overrun = 0;
1884 /* indicate buffer work may resume */
1885 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1886 n_tty_set_termios(tty, NULL);
1887 tty_unthrottle(tty);
1894 static inline int input_available_p(struct tty_struct *tty, int poll)
1896 struct n_tty_data *ldata = tty->disc_data;
1897 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
1899 if (ldata->icanon && !L_EXTPROC(tty))
1900 return ldata->canon_head != ldata->read_tail;
1902 return ldata->commit_head - ldata->read_tail >= amt;
1906 * copy_from_read_buf - copy read data directly
1907 * @tty: terminal device
1911 * Helper function to speed up n_tty_read. It is only called when
1912 * ICANON is off; it copies characters straight from the tty queue to
1913 * user space directly. It can be profitably called twice; once to
1914 * drain the space from the tail pointer to the (physical) end of the
1915 * buffer, and once to drain the space from the (physical) beginning of
1916 * the buffer to head pointer.
1918 * Called under the ldata->atomic_read_lock sem
1920 * n_tty_read()/consumer path:
1921 * caller holds non-exclusive termios_rwsem
1922 * read_tail published
1925 static int copy_from_read_buf(struct tty_struct *tty,
1926 unsigned char __user **b,
1930 struct n_tty_data *ldata = tty->disc_data;
1934 size_t head = smp_load_acquire(&ldata->commit_head);
1935 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1938 n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail);
1941 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1943 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1944 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1946 smp_store_release(&ldata->read_tail, ldata->read_tail + n);
1947 /* Turn single EOF into zero-length read */
1948 if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
1949 (head == ldata->read_tail))
1958 * canon_copy_from_read_buf - copy read data in canonical mode
1959 * @tty: terminal device
1963 * Helper function for n_tty_read. It is only called when ICANON is on;
1964 * it copies one line of input up to and including the line-delimiting
1965 * character into the user-space buffer.
1967 * NB: When termios is changed from non-canonical to canonical mode and
1968 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1969 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1970 * This causes data already processed as input to be immediately available
1971 * as input although a newline has not been received.
1973 * Called under the atomic_read_lock mutex
1975 * n_tty_read()/consumer path:
1976 * caller holds non-exclusive termios_rwsem
1977 * read_tail published
1980 static int canon_copy_from_read_buf(struct tty_struct *tty,
1981 unsigned char __user **b,
1984 struct n_tty_data *ldata = tty->disc_data;
1985 size_t n, size, more, c;
1991 /* N.B. avoid overrun if nr == 0 */
1992 n = min(*nr, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
1996 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1997 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
1999 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2000 __func__, *nr, tail, n, size);
2002 eol = find_next_bit(ldata->read_flags, size, tail);
2003 more = n - (size - tail);
2004 if (eol == N_TTY_BUF_SIZE && more) {
2005 /* scan wrapped without finding set bit */
2006 eol = find_next_bit(ldata->read_flags, more, 0);
2009 } else if (eol != size)
2012 size = N_TTY_BUF_SIZE - tail;
2019 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
2021 eof_push = !n && ldata->read_tail != ldata->line_start;
2024 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2025 __func__, eol, found, n, c, size, more);
2028 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2031 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2033 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2041 clear_bit(eol, ldata->read_flags);
2042 smp_store_release(&ldata->read_tail, ldata->read_tail + c);
2046 ldata->line_start = ldata->read_tail;
2049 tty_audit_push(tty);
2051 return eof_push ? -EAGAIN : 0;
2054 extern ssize_t redirected_tty_write(struct file *, const char __user *,
2058 * job_control - check job control
2060 * @file: file handle
2062 * Perform job control management checks on this file/tty descriptor
2063 * and if appropriate send any needed signals and return a negative
2064 * error code if action should be taken.
2066 * Locking: redirected write test is safe
2067 * current->signal->tty check is safe
2068 * ctrl_lock to safely reference tty->pgrp
2071 static int job_control(struct tty_struct *tty, struct file *file)
2073 /* Job control check -- must be done at start and after
2074 every sleep (POSIX.1 7.1.1.4). */
2075 /* NOTE: not yet done after every sleep pending a thorough
2076 check of the logic of this change. -- jlc */
2077 /* don't stop on /dev/console */
2078 if (file->f_op->write == redirected_tty_write ||
2079 current->signal->tty != tty)
2082 spin_lock_irq(&tty->ctrl_lock);
2084 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2085 else if (task_pgrp(current) != tty->pgrp) {
2086 spin_unlock_irq(&tty->ctrl_lock);
2087 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2089 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2090 set_thread_flag(TIF_SIGPENDING);
2091 return -ERESTARTSYS;
2093 spin_unlock_irq(&tty->ctrl_lock);
2099 * n_tty_read - read function for tty
2101 * @file: file object
2102 * @buf: userspace buffer pointer
2105 * Perform reads for the line discipline. We are guaranteed that the
2106 * line discipline will not be closed under us but we may get multiple
2107 * parallel readers and must handle this ourselves. We may also get
2108 * a hangup. Always called in user context, may sleep.
2110 * This code must be sure never to sleep through a hangup.
2112 * n_tty_read()/consumer path:
2113 * claims non-exclusive termios_rwsem
2114 * publishes read_tail
2117 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2118 unsigned char __user *buf, size_t nr)
2120 struct n_tty_data *ldata = tty->disc_data;
2121 unsigned char __user *b = buf;
2122 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2130 c = job_control(tty, file);
2135 * Internal serialization of reads.
2137 if (file->f_flags & O_NONBLOCK) {
2138 if (!mutex_trylock(&ldata->atomic_read_lock))
2141 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2142 return -ERESTARTSYS;
2145 down_read(&tty->termios_rwsem);
2148 timeout = MAX_SCHEDULE_TIMEOUT;
2149 if (!ldata->icanon) {
2150 minimum = MIN_CHAR(tty);
2152 time = (HZ / 10) * TIME_CHAR(tty);
2154 ldata->minimum_to_wake = 1;
2155 else if (!waitqueue_active(&tty->read_wait) ||
2156 (ldata->minimum_to_wake > minimum))
2157 ldata->minimum_to_wake = minimum;
2159 timeout = (HZ / 10) * TIME_CHAR(tty);
2160 ldata->minimum_to_wake = minimum = 1;
2164 packet = tty->packet;
2165 tail = ldata->read_tail;
2167 add_wait_queue(&tty->read_wait, &wait);
2169 /* First test for status change. */
2170 if (packet && tty->link->ctrl_status) {
2174 spin_lock_irq(&tty->link->ctrl_lock);
2175 cs = tty->link->ctrl_status;
2176 tty->link->ctrl_status = 0;
2177 spin_unlock_irq(&tty->link->ctrl_lock);
2178 if (tty_put_user(tty, cs, b++)) {
2187 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2188 ((minimum - (b - buf)) >= 1))
2189 ldata->minimum_to_wake = (minimum - (b - buf));
2191 if (!input_available_p(tty, 0)) {
2192 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2196 if (tty_hung_up_p(file))
2200 if (file->f_flags & O_NONBLOCK) {
2204 if (signal_pending(current)) {
2205 retval = -ERESTARTSYS;
2208 up_read(&tty->termios_rwsem);
2210 timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
2213 down_read(&tty->termios_rwsem);
2217 if (ldata->icanon && !L_EXTPROC(tty)) {
2218 retval = canon_copy_from_read_buf(tty, &b, &nr);
2219 if (retval == -EAGAIN) {
2227 /* Deal with packet mode. */
2228 if (packet && b == buf) {
2229 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2237 uncopied = copy_from_read_buf(tty, &b, &nr);
2238 uncopied += copy_from_read_buf(tty, &b, &nr);
2245 n_tty_check_unthrottle(tty);
2247 if (b - buf >= minimum)
2252 if (tail != ldata->read_tail)
2253 n_tty_kick_worker(tty);
2254 up_read(&tty->termios_rwsem);
2256 remove_wait_queue(&tty->read_wait, &wait);
2257 if (!waitqueue_active(&tty->read_wait))
2258 ldata->minimum_to_wake = minimum;
2260 mutex_unlock(&ldata->atomic_read_lock);
2269 * n_tty_write - write function for tty
2271 * @file: file object
2272 * @buf: userspace buffer pointer
2275 * Write function of the terminal device. This is serialized with
2276 * respect to other write callers but not to termios changes, reads
2277 * and other such events. Since the receive code will echo characters,
2278 * thus calling driver write methods, the output_lock is used in
2279 * the output processing functions called here as well as in the
2280 * echo processing function to protect the column state and space
2281 * left in the buffer.
2283 * This code must be sure never to sleep through a hangup.
2285 * Locking: output_lock to protect column state and space left
2286 * (note that the process_output*() functions take this
2290 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2291 const unsigned char *buf, size_t nr)
2293 const unsigned char *b = buf;
2294 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2298 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2299 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2300 retval = tty_check_change(tty);
2305 down_read(&tty->termios_rwsem);
2307 /* Write out any echoed characters that are still pending */
2308 process_echoes(tty);
2310 add_wait_queue(&tty->write_wait, &wait);
2312 if (signal_pending(current)) {
2313 retval = -ERESTARTSYS;
2316 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2322 ssize_t num = process_output_block(tty, b, nr);
2334 if (process_output(c, tty) < 0)
2338 if (tty->ops->flush_chars)
2339 tty->ops->flush_chars(tty);
2341 struct n_tty_data *ldata = tty->disc_data;
2344 mutex_lock(&ldata->output_lock);
2345 c = tty->ops->write(tty, b, nr);
2346 mutex_unlock(&ldata->output_lock);
2359 if (file->f_flags & O_NONBLOCK) {
2363 up_read(&tty->termios_rwsem);
2365 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
2367 down_read(&tty->termios_rwsem);
2370 remove_wait_queue(&tty->write_wait, &wait);
2371 if (b - buf != nr && tty->fasync)
2372 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2373 up_read(&tty->termios_rwsem);
2374 return (b - buf) ? b - buf : retval;
2378 * n_tty_poll - poll method for N_TTY
2379 * @tty: terminal device
2380 * @file: file accessing it
2383 * Called when the line discipline is asked to poll() for data or
2384 * for special events. This code is not serialized with respect to
2385 * other events save open/close.
2387 * This code must be sure never to sleep through a hangup.
2388 * Called without the kernel lock held - fine
2391 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2394 struct n_tty_data *ldata = tty->disc_data;
2395 unsigned int mask = 0;
2397 poll_wait(file, &tty->read_wait, wait);
2398 poll_wait(file, &tty->write_wait, wait);
2399 if (input_available_p(tty, 1))
2400 mask |= POLLIN | POLLRDNORM;
2401 if (tty->packet && tty->link->ctrl_status)
2402 mask |= POLLPRI | POLLIN | POLLRDNORM;
2403 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2405 if (tty_hung_up_p(file))
2407 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2408 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2409 ldata->minimum_to_wake = MIN_CHAR(tty);
2411 ldata->minimum_to_wake = 1;
2413 if (tty->ops->write && !tty_is_writelocked(tty) &&
2414 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2415 tty_write_room(tty) > 0)
2416 mask |= POLLOUT | POLLWRNORM;
2420 static unsigned long inq_canon(struct n_tty_data *ldata)
2422 size_t nr, head, tail;
2424 if (ldata->canon_head == ldata->read_tail)
2426 head = ldata->canon_head;
2427 tail = ldata->read_tail;
2429 /* Skip EOF-chars.. */
2430 while (head != tail) {
2431 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2432 read_buf(ldata, tail) == __DISABLED_CHAR)
2439 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2440 unsigned int cmd, unsigned long arg)
2442 struct n_tty_data *ldata = tty->disc_data;
2447 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2449 down_write(&tty->termios_rwsem);
2451 retval = inq_canon(ldata);
2453 retval = read_cnt(ldata);
2454 up_write(&tty->termios_rwsem);
2455 return put_user(retval, (unsigned int __user *) arg);
2457 return n_tty_ioctl_helper(tty, file, cmd, arg);
2461 static void n_tty_fasync(struct tty_struct *tty, int on)
2463 struct n_tty_data *ldata = tty->disc_data;
2465 if (!waitqueue_active(&tty->read_wait)) {
2467 ldata->minimum_to_wake = 1;
2468 else if (!tty->fasync)
2469 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2473 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2474 .magic = TTY_LDISC_MAGIC,
2477 .close = n_tty_close,
2478 .flush_buffer = n_tty_flush_buffer,
2479 .chars_in_buffer = n_tty_chars_in_buffer,
2481 .write = n_tty_write,
2482 .ioctl = n_tty_ioctl,
2483 .set_termios = n_tty_set_termios,
2485 .receive_buf = n_tty_receive_buf,
2486 .write_wakeup = n_tty_write_wakeup,
2487 .fasync = n_tty_fasync,
2488 .receive_buf2 = n_tty_receive_buf2,
2492 * n_tty_inherit_ops - inherit N_TTY methods
2493 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2495 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2499 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2501 *ops = tty_ldisc_N_TTY;
2503 ops->refcount = ops->flags = 0;
2505 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);