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
);
165 static int tty_copy_to_user(struct tty_struct
*tty
, void __user
*to
,
166 size_t tail
, size_t n
)
168 struct n_tty_data
*ldata
= tty
->disc_data
;
169 size_t size
= N_TTY_BUF_SIZE
- tail
;
170 const void *from
= read_buf_addr(ldata
, tail
);
174 tty_audit_add_data(tty
, from
, size
, ldata
->icanon
);
175 uncopied
= copy_to_user(to
, from
, size
);
180 from
= ldata
->read_buf
;
183 tty_audit_add_data(tty
, from
, n
, ldata
->icanon
);
184 return copy_to_user(to
, from
, n
);
188 * n_tty_kick_worker - start input worker (if required)
191 * Re-schedules the flip buffer work if it may have stopped
193 * Caller holds exclusive termios_rwsem
195 * n_tty_read()/consumer path:
196 * holds non-exclusive termios_rwsem
199 static void n_tty_kick_worker(struct tty_struct
*tty
)
201 struct n_tty_data
*ldata
= tty
->disc_data
;
203 /* Did the input worker stop? Restart it */
204 if (unlikely(ldata
->no_room
)) {
207 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
208 "scheduling with invalid itty\n");
209 /* see if ldisc has been killed - if so, this means that
210 * even though the ldisc has been halted and ->buf.work
211 * cancelled, ->buf.work is about to be rescheduled
213 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
214 "scheduling buffer work for halted ldisc\n");
215 tty_buffer_restart_work(tty
->port
);
219 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
221 struct n_tty_data
*ldata
= tty
->disc_data
;
225 n
= ldata
->commit_head
- ldata
->read_tail
;
227 n
= ldata
->canon_head
- ldata
->read_tail
;
232 * n_tty_write_wakeup - asynchronous I/O notifier
235 * Required for the ptys, serial driver etc. since processes
236 * that attach themselves to the master and rely on ASYNC
237 * IO must be woken up
240 static void n_tty_write_wakeup(struct tty_struct
*tty
)
242 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
243 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
246 static void n_tty_check_throttle(struct tty_struct
*tty
)
248 struct n_tty_data
*ldata
= tty
->disc_data
;
251 * Check the remaining room for the input canonicalization
252 * mode. We don't want to throttle the driver if we're in
253 * canonical mode and don't have a newline yet!
255 if (ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
)
260 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
261 if (N_TTY_BUF_SIZE
- read_cnt(ldata
) >= TTY_THRESHOLD_THROTTLE
)
263 throttled
= tty_throttle_safe(tty
);
267 __tty_set_flow_change(tty
, 0);
270 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
272 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
273 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
274 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
278 n_tty_kick_worker(tty
);
279 n_tty_write_wakeup(tty
->link
);
280 if (waitqueue_active(&tty
->link
->write_wait
))
281 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
285 /* If there is enough space in the read buffer now, let the
286 * low-level driver know. We use chars_in_buffer() to
287 * check the buffer, as it now knows about canonical mode.
288 * Otherwise, if the driver is throttled and the line is
289 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
290 * we won't get any more characters.
295 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
296 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
300 n_tty_kick_worker(tty
);
301 unthrottled
= tty_unthrottle_safe(tty
);
305 __tty_set_flow_change(tty
, 0);
309 * put_tty_queue - add character to tty
313 * Add a character to the tty read_buf queue.
315 * n_tty_receive_buf()/producer path:
316 * caller holds non-exclusive termios_rwsem
319 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
321 *read_buf_addr(ldata
, ldata
->read_head
) = c
;
326 * reset_buffer_flags - reset buffer state
327 * @tty: terminal to reset
329 * Reset the read buffer counters and clear the flags.
330 * Called from n_tty_open() and n_tty_flush_buffer().
332 * Locking: caller holds exclusive termios_rwsem
333 * (or locking is not required)
336 static void reset_buffer_flags(struct n_tty_data
*ldata
)
338 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
339 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
340 ldata
->commit_head
= 0;
341 ldata
->echo_mark
= 0;
342 ldata
->line_start
= 0;
345 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
349 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
353 if (tty
->link
->packet
) {
354 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
355 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
356 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
357 wake_up_interruptible(&tty
->link
->read_wait
);
362 * n_tty_flush_buffer - clean input queue
363 * @tty: terminal device
365 * Flush the input buffer. Called when the tty layer wants the
366 * buffer flushed (eg at hangup) or when the N_TTY line discipline
367 * internally has to clean the pending queue (for example some signals).
369 * Holds termios_rwsem to exclude producer/consumer while
370 * buffer indices are reset.
372 * Locking: ctrl_lock, exclusive termios_rwsem
375 static void n_tty_flush_buffer(struct tty_struct
*tty
)
377 down_write(&tty
->termios_rwsem
);
378 reset_buffer_flags(tty
->disc_data
);
379 n_tty_kick_worker(tty
);
382 n_tty_packet_mode_flush(tty
);
383 up_write(&tty
->termios_rwsem
);
387 * n_tty_chars_in_buffer - report available bytes
390 * Report the number of characters buffered to be delivered to user
391 * at this instant in time.
393 * Locking: exclusive termios_rwsem
396 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
400 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
402 down_write(&tty
->termios_rwsem
);
403 n
= chars_in_buffer(tty
);
404 up_write(&tty
->termios_rwsem
);
409 * is_utf8_continuation - utf8 multibyte check
412 * Returns true if the utf8 character 'c' is a multibyte continuation
413 * character. We use this to correctly compute the on screen size
414 * of the character when printing
417 static inline int is_utf8_continuation(unsigned char c
)
419 return (c
& 0xc0) == 0x80;
423 * is_continuation - multibyte check
426 * Returns true if the utf8 character 'c' is a multibyte continuation
427 * character and the terminal is in unicode mode.
430 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
432 return I_IUTF8(tty
) && is_utf8_continuation(c
);
436 * do_output_char - output one character
437 * @c: character (or partial unicode symbol)
438 * @tty: terminal device
439 * @space: space available in tty driver write buffer
441 * This is a helper function that handles one output character
442 * (including special characters like TAB, CR, LF, etc.),
443 * doing OPOST processing and putting the results in the
444 * tty driver's write buffer.
446 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
447 * and NLDLY. They simply aren't relevant in the world today.
448 * If you ever need them, add them here.
450 * Returns the number of bytes of buffer space used or -1 if
453 * Locking: should be called under the output_lock to protect
454 * the column state and space left in the buffer
457 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
459 struct n_tty_data
*ldata
= tty
->disc_data
;
472 ldata
->canon_column
= ldata
->column
= 0;
473 tty
->ops
->write(tty
, "\r\n", 2);
476 ldata
->canon_column
= ldata
->column
;
479 if (O_ONOCR(tty
) && ldata
->column
== 0)
484 ldata
->canon_column
= ldata
->column
= 0;
487 ldata
->canon_column
= ldata
->column
= 0;
490 spaces
= 8 - (ldata
->column
& 7);
491 if (O_TABDLY(tty
) == XTABS
) {
494 ldata
->column
+= spaces
;
495 tty
->ops
->write(tty
, " ", spaces
);
498 ldata
->column
+= spaces
;
501 if (ldata
->column
> 0)
508 if (!is_continuation(c
, tty
))
514 tty_put_char(tty
, c
);
519 * process_output - output post processor
520 * @c: character (or partial unicode symbol)
521 * @tty: terminal device
523 * Output one character with OPOST processing.
524 * Returns -1 when the output device is full and the character
527 * Locking: output_lock to protect column state and space left
528 * (also, this is called from n_tty_write under the
529 * tty layer write lock)
532 static int process_output(unsigned char c
, struct tty_struct
*tty
)
534 struct n_tty_data
*ldata
= tty
->disc_data
;
537 mutex_lock(&ldata
->output_lock
);
539 space
= tty_write_room(tty
);
540 retval
= do_output_char(c
, tty
, space
);
542 mutex_unlock(&ldata
->output_lock
);
550 * process_output_block - block post processor
551 * @tty: terminal device
552 * @buf: character buffer
553 * @nr: number of bytes to output
555 * Output a block of characters with OPOST processing.
556 * Returns the number of characters output.
558 * This path is used to speed up block console writes, among other
559 * things when processing blocks of output data. It handles only
560 * the simple cases normally found and helps to generate blocks of
561 * symbols for the console driver and thus improve performance.
563 * Locking: output_lock to protect column state and space left
564 * (also, this is called from n_tty_write under the
565 * tty layer write lock)
568 static ssize_t
process_output_block(struct tty_struct
*tty
,
569 const unsigned char *buf
, unsigned int nr
)
571 struct n_tty_data
*ldata
= tty
->disc_data
;
574 const unsigned char *cp
;
576 mutex_lock(&ldata
->output_lock
);
578 space
= tty_write_room(tty
);
580 mutex_unlock(&ldata
->output_lock
);
586 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
587 unsigned char c
= *cp
;
595 ldata
->canon_column
= ldata
->column
;
598 if (O_ONOCR(tty
) && ldata
->column
== 0)
602 ldata
->canon_column
= ldata
->column
= 0;
607 if (ldata
->column
> 0)
614 if (!is_continuation(c
, tty
))
621 i
= tty
->ops
->write(tty
, buf
, i
);
623 mutex_unlock(&ldata
->output_lock
);
628 * process_echoes - write pending echo characters
629 * @tty: terminal device
631 * Write previously buffered echo (and other ldisc-generated)
632 * characters to the tty.
634 * Characters generated by the ldisc (including echoes) need to
635 * be buffered because the driver's write buffer can fill during
636 * heavy program output. Echoing straight to the driver will
637 * often fail under these conditions, causing lost characters and
638 * resulting mismatches of ldisc state information.
640 * Since the ldisc state must represent the characters actually sent
641 * to the driver at the time of the write, operations like certain
642 * changes in column state are also saved in the buffer and executed
645 * A circular fifo buffer is used so that the most recent characters
646 * are prioritized. Also, when control characters are echoed with a
647 * prefixed "^", the pair is treated atomically and thus not separated.
649 * Locking: callers must hold output_lock
652 static size_t __process_echoes(struct tty_struct
*tty
)
654 struct n_tty_data
*ldata
= tty
->disc_data
;
655 int space
, old_space
;
659 old_space
= space
= tty_write_room(tty
);
661 tail
= ldata
->echo_tail
;
662 while (ldata
->echo_commit
!= tail
) {
663 c
= echo_buf(ldata
, tail
);
664 if (c
== ECHO_OP_START
) {
666 int no_space_left
= 0;
669 * If the buffer byte is the start of a multi-byte
670 * operation, get the next byte, which is either the
671 * op code or a control character value.
673 op
= echo_buf(ldata
, tail
+ 1);
676 unsigned int num_chars
, num_bs
;
678 case ECHO_OP_ERASE_TAB
:
679 num_chars
= echo_buf(ldata
, tail
+ 2);
682 * Determine how many columns to go back
683 * in order to erase the tab.
684 * This depends on the number of columns
685 * used by other characters within the tab
686 * area. If this (modulo 8) count is from
687 * the start of input rather than from a
688 * previous tab, we offset by canon column.
689 * Otherwise, tab spacing is normal.
691 if (!(num_chars
& 0x80))
692 num_chars
+= ldata
->canon_column
;
693 num_bs
= 8 - (num_chars
& 7);
695 if (num_bs
> space
) {
701 tty_put_char(tty
, '\b');
702 if (ldata
->column
> 0)
708 case ECHO_OP_SET_CANON_COL
:
709 ldata
->canon_column
= ldata
->column
;
713 case ECHO_OP_MOVE_BACK_COL
:
714 if (ldata
->column
> 0)
720 /* This is an escaped echo op start code */
725 tty_put_char(tty
, ECHO_OP_START
);
733 * If the op is not a special byte code,
734 * it is a ctrl char tagged to be echoed
735 * as "^X" (where X is the letter
736 * representing the control char).
737 * Note that we must ensure there is
738 * enough space for the whole ctrl pair.
745 tty_put_char(tty
, '^');
746 tty_put_char(tty
, op
^ 0100);
756 int retval
= do_output_char(c
, tty
, space
);
763 tty_put_char(tty
, c
);
770 /* If the echo buffer is nearly full (so that the possibility exists
771 * of echo overrun before the next commit), then discard enough
772 * data at the tail to prevent a subsequent overrun */
773 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
774 if (echo_buf(ldata
, tail
) == ECHO_OP_START
) {
775 if (echo_buf(ldata
, tail
+ 1) == ECHO_OP_ERASE_TAB
)
783 ldata
->echo_tail
= tail
;
784 return old_space
- space
;
787 static void commit_echoes(struct tty_struct
*tty
)
789 struct n_tty_data
*ldata
= tty
->disc_data
;
790 size_t nr
, old
, echoed
;
793 head
= ldata
->echo_head
;
794 ldata
->echo_mark
= head
;
795 old
= ldata
->echo_commit
- ldata
->echo_tail
;
797 /* Process committed echoes if the accumulated # of bytes
798 * is over the threshold (and try again each time another
799 * block is accumulated) */
800 nr
= head
- ldata
->echo_tail
;
801 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
804 mutex_lock(&ldata
->output_lock
);
805 ldata
->echo_commit
= head
;
806 echoed
= __process_echoes(tty
);
807 mutex_unlock(&ldata
->output_lock
);
809 if (echoed
&& tty
->ops
->flush_chars
)
810 tty
->ops
->flush_chars(tty
);
813 static void process_echoes(struct tty_struct
*tty
)
815 struct n_tty_data
*ldata
= tty
->disc_data
;
818 if (ldata
->echo_mark
== ldata
->echo_tail
)
821 mutex_lock(&ldata
->output_lock
);
822 ldata
->echo_commit
= ldata
->echo_mark
;
823 echoed
= __process_echoes(tty
);
824 mutex_unlock(&ldata
->output_lock
);
826 if (echoed
&& tty
->ops
->flush_chars
)
827 tty
->ops
->flush_chars(tty
);
830 /* NB: echo_mark and echo_head should be equivalent here */
831 static void flush_echoes(struct tty_struct
*tty
)
833 struct n_tty_data
*ldata
= tty
->disc_data
;
835 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
836 ldata
->echo_commit
== ldata
->echo_head
)
839 mutex_lock(&ldata
->output_lock
);
840 ldata
->echo_commit
= ldata
->echo_head
;
841 __process_echoes(tty
);
842 mutex_unlock(&ldata
->output_lock
);
846 * add_echo_byte - add a byte to the echo buffer
847 * @c: unicode byte to echo
850 * Add a character or operation byte to the echo buffer.
853 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
855 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
859 * echo_move_back_col - add operation to move back a column
862 * Add an operation to the echo buffer to move back one column.
865 static void echo_move_back_col(struct n_tty_data
*ldata
)
867 add_echo_byte(ECHO_OP_START
, ldata
);
868 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
872 * echo_set_canon_col - add operation to set the canon column
875 * Add an operation to the echo buffer to set the canon column
876 * to the current column.
879 static void echo_set_canon_col(struct n_tty_data
*ldata
)
881 add_echo_byte(ECHO_OP_START
, ldata
);
882 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
886 * echo_erase_tab - add operation to erase a tab
887 * @num_chars: number of character columns already used
888 * @after_tab: true if num_chars starts after a previous tab
891 * Add an operation to the echo buffer to erase a tab.
893 * Called by the eraser function, which knows how many character
894 * columns have been used since either a previous tab or the start
895 * of input. This information will be used later, along with
896 * canon column (if applicable), to go back the correct number
900 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
901 struct n_tty_data
*ldata
)
903 add_echo_byte(ECHO_OP_START
, ldata
);
904 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
906 /* We only need to know this modulo 8 (tab spacing) */
909 /* Set the high bit as a flag if num_chars is after a previous tab */
913 add_echo_byte(num_chars
, ldata
);
917 * echo_char_raw - echo a character raw
918 * @c: unicode byte to echo
919 * @tty: terminal device
921 * Echo user input back onto the screen. This must be called only when
922 * L_ECHO(tty) is true. Called from the driver receive_buf path.
924 * This variant does not treat control characters specially.
927 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
929 if (c
== ECHO_OP_START
) {
930 add_echo_byte(ECHO_OP_START
, ldata
);
931 add_echo_byte(ECHO_OP_START
, ldata
);
933 add_echo_byte(c
, ldata
);
938 * echo_char - echo a character
939 * @c: unicode byte to echo
940 * @tty: terminal device
942 * Echo user input back onto the screen. This must be called only when
943 * L_ECHO(tty) is true. Called from the driver receive_buf path.
945 * This variant tags control characters to be echoed as "^X"
946 * (where X is the letter representing the control char).
949 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
951 struct n_tty_data
*ldata
= tty
->disc_data
;
953 if (c
== ECHO_OP_START
) {
954 add_echo_byte(ECHO_OP_START
, ldata
);
955 add_echo_byte(ECHO_OP_START
, ldata
);
957 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
958 add_echo_byte(ECHO_OP_START
, ldata
);
959 add_echo_byte(c
, ldata
);
964 * finish_erasing - complete erase
968 static inline void finish_erasing(struct n_tty_data
*ldata
)
970 if (ldata
->erasing
) {
971 echo_char_raw('/', ldata
);
977 * eraser - handle erase function
978 * @c: character input
979 * @tty: terminal device
981 * Perform erase and necessary output when an erase character is
982 * present in the stream from the driver layer. Handles the complexities
983 * of UTF-8 multibyte symbols.
985 * n_tty_receive_buf()/producer path:
986 * caller holds non-exclusive termios_rwsem
989 static void eraser(unsigned char c
, struct tty_struct
*tty
)
991 struct n_tty_data
*ldata
= tty
->disc_data
;
992 enum { ERASE
, WERASE
, KILL
} kill_type
;
997 if (ldata
->read_head
== ldata
->canon_head
) {
998 /* process_output('\a', tty); */ /* what do you think? */
1001 if (c
== ERASE_CHAR(tty
))
1003 else if (c
== WERASE_CHAR(tty
))
1007 ldata
->read_head
= ldata
->canon_head
;
1010 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1011 ldata
->read_head
= ldata
->canon_head
;
1012 finish_erasing(ldata
);
1013 echo_char(KILL_CHAR(tty
), tty
);
1014 /* Add a newline if ECHOK is on and ECHOKE is off. */
1016 echo_char_raw('\n', ldata
);
1023 while (ldata
->read_head
!= ldata
->canon_head
) {
1024 head
= ldata
->read_head
;
1026 /* erase a single possibly multibyte character */
1029 c
= read_buf(ldata
, head
);
1030 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1032 /* do not partially erase */
1033 if (is_continuation(c
, tty
))
1036 if (kill_type
== WERASE
) {
1037 /* Equivalent to BSD's ALTWERASE. */
1038 if (isalnum(c
) || c
== '_')
1040 else if (seen_alnums
)
1043 cnt
= ldata
->read_head
- head
;
1044 ldata
->read_head
= head
;
1046 if (L_ECHOPRT(tty
)) {
1047 if (!ldata
->erasing
) {
1048 echo_char_raw('\\', ldata
);
1051 /* if cnt > 1, output a multi-byte character */
1055 echo_char_raw(read_buf(ldata
, head
), ldata
);
1056 echo_move_back_col(ldata
);
1058 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1059 echo_char(ERASE_CHAR(tty
), tty
);
1060 } else if (c
== '\t') {
1061 unsigned int num_chars
= 0;
1063 size_t tail
= ldata
->read_head
;
1066 * Count the columns used for characters
1067 * since the start of input or after a
1069 * This info is used to go back the correct
1070 * number of columns.
1072 while (tail
!= ldata
->canon_head
) {
1074 c
= read_buf(ldata
, tail
);
1078 } else if (iscntrl(c
)) {
1081 } else if (!is_continuation(c
, tty
)) {
1085 echo_erase_tab(num_chars
, after_tab
, ldata
);
1087 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1088 echo_char_raw('\b', ldata
);
1089 echo_char_raw(' ', ldata
);
1090 echo_char_raw('\b', ldata
);
1092 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1093 echo_char_raw('\b', ldata
);
1094 echo_char_raw(' ', ldata
);
1095 echo_char_raw('\b', ldata
);
1099 if (kill_type
== ERASE
)
1102 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1103 finish_erasing(ldata
);
1107 * isig - handle the ISIG optio
1111 * Called when a signal is being sent due to terminal input.
1112 * Called from the driver receive_buf path so serialized.
1114 * Performs input and output flush if !NOFLSH. In this context, the echo
1115 * buffer is 'output'. The signal is processed first to alert any current
1116 * readers or writers to discontinue and exit their i/o loops.
1118 * Locking: ctrl_lock
1121 static void __isig(int sig
, struct tty_struct
*tty
)
1123 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1125 kill_pgrp(tty_pgrp
, sig
, 1);
1130 static void isig(int sig
, struct tty_struct
*tty
)
1132 struct n_tty_data
*ldata
= tty
->disc_data
;
1134 if (L_NOFLSH(tty
)) {
1138 } else { /* signal and flush */
1139 up_read(&tty
->termios_rwsem
);
1140 down_write(&tty
->termios_rwsem
);
1144 /* clear echo buffer */
1145 mutex_lock(&ldata
->output_lock
);
1146 ldata
->echo_head
= ldata
->echo_tail
= 0;
1147 ldata
->echo_mark
= ldata
->echo_commit
= 0;
1148 mutex_unlock(&ldata
->output_lock
);
1150 /* clear output buffer */
1151 tty_driver_flush_buffer(tty
);
1153 /* clear input buffer */
1154 reset_buffer_flags(tty
->disc_data
);
1156 /* notify pty master of flush */
1158 n_tty_packet_mode_flush(tty
);
1160 up_write(&tty
->termios_rwsem
);
1161 down_read(&tty
->termios_rwsem
);
1166 * n_tty_receive_break - handle break
1169 * An RS232 break event has been hit in the incoming bitstream. This
1170 * can cause a variety of events depending upon the termios settings.
1172 * n_tty_receive_buf()/producer path:
1173 * caller holds non-exclusive termios_rwsem
1175 * Note: may get exclusive termios_rwsem if flushing input buffer
1178 static void n_tty_receive_break(struct tty_struct
*tty
)
1180 struct n_tty_data
*ldata
= tty
->disc_data
;
1184 if (I_BRKINT(tty
)) {
1188 if (I_PARMRK(tty
)) {
1189 put_tty_queue('\377', ldata
);
1190 put_tty_queue('\0', ldata
);
1192 put_tty_queue('\0', ldata
);
1196 * n_tty_receive_overrun - handle overrun reporting
1199 * Data arrived faster than we could process it. While the tty
1200 * driver has flagged this the bits that were missed are gone
1203 * Called from the receive_buf path so single threaded. Does not
1204 * need locking as num_overrun and overrun_time are function
1208 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1210 struct n_tty_data
*ldata
= tty
->disc_data
;
1212 ldata
->num_overrun
++;
1213 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1214 time_after(ldata
->overrun_time
, jiffies
)) {
1215 tty_warn(tty
, "%d input overrun(s)\n", ldata
->num_overrun
);
1216 ldata
->overrun_time
= jiffies
;
1217 ldata
->num_overrun
= 0;
1222 * n_tty_receive_parity_error - error notifier
1223 * @tty: terminal device
1226 * Process a parity error and queue the right data to indicate
1227 * the error case if necessary.
1229 * n_tty_receive_buf()/producer path:
1230 * caller holds non-exclusive termios_rwsem
1232 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1234 struct n_tty_data
*ldata
= tty
->disc_data
;
1239 if (I_PARMRK(tty
)) {
1240 put_tty_queue('\377', ldata
);
1241 put_tty_queue('\0', ldata
);
1242 put_tty_queue(c
, ldata
);
1244 put_tty_queue('\0', ldata
);
1246 put_tty_queue(c
, ldata
);
1250 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1259 process_echoes(tty
);
1264 * n_tty_receive_char - perform processing
1265 * @tty: terminal device
1268 * Process an individual character of input received from the driver.
1269 * This is serialized with respect to itself by the rules for the
1272 * n_tty_receive_buf()/producer path:
1273 * caller holds non-exclusive termios_rwsem
1274 * publishes canon_head if canonical mode is active
1276 * Returns 1 if LNEXT was received, else returns 0
1280 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1282 struct n_tty_data
*ldata
= tty
->disc_data
;
1285 if (c
== START_CHAR(tty
)) {
1287 process_echoes(tty
);
1290 if (c
== STOP_CHAR(tty
)) {
1297 if (c
== INTR_CHAR(tty
)) {
1298 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1300 } else if (c
== QUIT_CHAR(tty
)) {
1301 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1303 } else if (c
== SUSP_CHAR(tty
)) {
1304 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1309 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1311 process_echoes(tty
);
1319 } else if (c
== '\n' && I_INLCR(tty
))
1322 if (ldata
->icanon
) {
1323 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1324 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1329 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1332 finish_erasing(ldata
);
1333 if (L_ECHOCTL(tty
)) {
1334 echo_char_raw('^', ldata
);
1335 echo_char_raw('\b', ldata
);
1341 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1342 size_t tail
= ldata
->canon_head
;
1344 finish_erasing(ldata
);
1346 echo_char_raw('\n', ldata
);
1347 while (tail
!= ldata
->read_head
) {
1348 echo_char(read_buf(ldata
, tail
), tty
);
1355 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1356 echo_char_raw('\n', ldata
);
1359 goto handle_newline
;
1361 if (c
== EOF_CHAR(tty
)) {
1362 c
= __DISABLED_CHAR
;
1363 goto handle_newline
;
1365 if ((c
== EOL_CHAR(tty
)) ||
1366 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1368 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1371 /* Record the column of first canon char. */
1372 if (ldata
->canon_head
== ldata
->read_head
)
1373 echo_set_canon_col(ldata
);
1378 * XXX does PARMRK doubling happen for
1379 * EOL_CHAR and EOL2_CHAR?
1381 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1382 put_tty_queue(c
, ldata
);
1385 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1386 put_tty_queue(c
, ldata
);
1387 smp_store_release(&ldata
->canon_head
, ldata
->read_head
);
1388 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1389 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1395 finish_erasing(ldata
);
1397 echo_char_raw('\n', ldata
);
1399 /* Record the column of first canon char. */
1400 if (ldata
->canon_head
== ldata
->read_head
)
1401 echo_set_canon_col(ldata
);
1407 /* PARMRK doubling check */
1408 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1409 put_tty_queue(c
, ldata
);
1411 put_tty_queue(c
, ldata
);
1416 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1418 struct n_tty_data
*ldata
= tty
->disc_data
;
1420 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1422 process_echoes(tty
);
1425 finish_erasing(ldata
);
1426 /* Record the column of first canon char. */
1427 if (ldata
->canon_head
== ldata
->read_head
)
1428 echo_set_canon_col(ldata
);
1432 /* PARMRK doubling check */
1433 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1434 put_tty_queue(c
, ldata
);
1435 put_tty_queue(c
, ldata
);
1438 static void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1440 n_tty_receive_char_inline(tty
, c
);
1444 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1446 struct n_tty_data
*ldata
= tty
->disc_data
;
1448 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1450 process_echoes(tty
);
1453 finish_erasing(ldata
);
1454 /* Record the column of first canon char. */
1455 if (ldata
->canon_head
== ldata
->read_head
)
1456 echo_set_canon_col(ldata
);
1460 put_tty_queue(c
, ldata
);
1463 static void n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1467 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1471 if (c
== STOP_CHAR(tty
))
1473 else if (c
== START_CHAR(tty
) ||
1474 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1475 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1476 c
!= SUSP_CHAR(tty
))) {
1478 process_echoes(tty
);
1484 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1488 n_tty_receive_break(tty
);
1492 n_tty_receive_parity_error(tty
, c
);
1495 n_tty_receive_overrun(tty
);
1498 tty_err(tty
, "unknown flag %d\n", flag
);
1504 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1506 struct n_tty_data
*ldata
= tty
->disc_data
;
1509 if (likely(flag
== TTY_NORMAL
)) {
1512 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1514 n_tty_receive_char(tty
, c
);
1516 n_tty_receive_char_flagged(tty
, c
, flag
);
1520 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1521 char *fp
, int count
)
1523 struct n_tty_data
*ldata
= tty
->disc_data
;
1526 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1527 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1528 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1529 ldata
->read_head
+= n
;
1533 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1534 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1535 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1536 ldata
->read_head
+= n
;
1540 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1541 char *fp
, int count
)
1543 struct n_tty_data
*ldata
= tty
->disc_data
;
1544 char flag
= TTY_NORMAL
;
1549 if (likely(flag
== TTY_NORMAL
))
1550 put_tty_queue(*cp
++, ldata
);
1552 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1557 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1558 char *fp
, int count
)
1560 char flag
= TTY_NORMAL
;
1565 if (likely(flag
== TTY_NORMAL
))
1566 n_tty_receive_char_closing(tty
, *cp
++);
1568 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1573 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1574 char *fp
, int count
)
1576 struct n_tty_data
*ldata
= tty
->disc_data
;
1577 char flag
= TTY_NORMAL
;
1582 if (likely(flag
== TTY_NORMAL
)) {
1583 unsigned char c
= *cp
++;
1587 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1589 if (L_EXTPROC(tty
)) {
1590 put_tty_queue(c
, ldata
);
1593 if (!test_bit(c
, ldata
->char_map
))
1594 n_tty_receive_char_inline(tty
, c
);
1595 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1598 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1602 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1607 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1608 char *fp
, int count
)
1610 struct n_tty_data
*ldata
= tty
->disc_data
;
1611 char flag
= TTY_NORMAL
;
1616 if (likely(flag
== TTY_NORMAL
)) {
1617 unsigned char c
= *cp
++;
1619 if (!test_bit(c
, ldata
->char_map
))
1620 n_tty_receive_char_fast(tty
, c
);
1621 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1624 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1628 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1632 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1633 char *fp
, int count
)
1635 struct n_tty_data
*ldata
= tty
->disc_data
;
1636 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1638 if (ldata
->real_raw
)
1639 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1640 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1641 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1642 else if (tty
->closing
&& !L_EXTPROC(tty
))
1643 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1646 char flag
= TTY_NORMAL
;
1650 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1654 if (!preops
&& !I_PARMRK(tty
))
1655 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1657 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1660 if (tty
->ops
->flush_chars
)
1661 tty
->ops
->flush_chars(tty
);
1664 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1667 /* publish read_head to consumer */
1668 smp_store_release(&ldata
->commit_head
, ldata
->read_head
);
1670 if ((read_cnt(ldata
) >= ldata
->minimum_to_wake
) || L_EXTPROC(tty
)) {
1671 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1672 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1677 * n_tty_receive_buf_common - process input
1678 * @tty: device to receive input
1680 * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
1681 * @count: number of input chars in @cp
1683 * Called by the terminal driver when a block of characters has
1684 * been received. This function must be called from soft contexts
1685 * not from interrupt context. The driver is responsible for making
1686 * calls one at a time and in order (or using flush_to_ldisc)
1688 * Returns the # of input chars from @cp which were processed.
1690 * In canonical mode, the maximum line length is 4096 chars (including
1691 * the line termination char); lines longer than 4096 chars are
1692 * truncated. After 4095 chars, input data is still processed but
1693 * not stored. Overflow processing ensures the tty can always
1694 * receive more input until at least one line can be read.
1696 * In non-canonical mode, the read buffer will only accept 4095 chars;
1697 * this provides the necessary space for a newline char if the input
1698 * mode is switched to canonical.
1700 * Note it is possible for the read buffer to _contain_ 4096 chars
1701 * in non-canonical mode: the read buffer could already contain the
1702 * maximum canon line of 4096 chars when the mode is switched to
1705 * n_tty_receive_buf()/producer path:
1706 * claims non-exclusive termios_rwsem
1707 * publishes commit_head or canon_head
1710 n_tty_receive_buf_common(struct tty_struct
*tty
, const unsigned char *cp
,
1711 char *fp
, int count
, int flow
)
1713 struct n_tty_data
*ldata
= tty
->disc_data
;
1714 int room
, n
, rcvd
= 0, overflow
;
1716 down_read(&tty
->termios_rwsem
);
1720 * When PARMRK is set, each input char may take up to 3 chars
1721 * in the read buf; reduce the buffer space avail by 3x
1723 * If we are doing input canonicalization, and there are no
1724 * pending newlines, let characters through without limit, so
1725 * that erase characters will be handled. Other excess
1726 * characters will be beeped.
1728 * paired with store in *_copy_from_read_buf() -- guarantees
1729 * the consumer has loaded the data in read_buf up to the new
1730 * read_tail (so this producer will not overwrite unread data)
1732 size_t tail
= smp_load_acquire(&ldata
->read_tail
);
1734 room
= N_TTY_BUF_SIZE
- (ldata
->read_head
- tail
);
1736 room
= (room
+ 2) / 3;
1739 overflow
= ldata
->icanon
&& ldata
->canon_head
== tail
;
1740 if (overflow
&& room
< 0)
1743 ldata
->no_room
= flow
&& !room
;
1747 n
= min(count
, room
);
1751 /* ignore parity errors if handling overflow */
1752 if (!overflow
|| !fp
|| *fp
!= TTY_PARITY
)
1753 __receive_buf(tty
, cp
, fp
, n
);
1762 tty
->receive_room
= room
;
1764 /* Unthrottle if handling overflow on pty */
1765 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
) {
1767 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
1768 tty_unthrottle_safe(tty
);
1769 __tty_set_flow_change(tty
, 0);
1772 n_tty_check_throttle(tty
);
1774 up_read(&tty
->termios_rwsem
);
1779 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1780 char *fp
, int count
)
1782 n_tty_receive_buf_common(tty
, cp
, fp
, count
, 0);
1785 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1786 char *fp
, int count
)
1788 return n_tty_receive_buf_common(tty
, cp
, fp
, count
, 1);
1791 int is_ignored(int sig
)
1793 return (sigismember(¤t
->blocked
, sig
) ||
1794 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1798 * n_tty_set_termios - termios data changed
1800 * @old: previous data
1802 * Called by the tty layer when the user changes termios flags so
1803 * that the line discipline can plan ahead. This function cannot sleep
1804 * and is protected from re-entry by the tty layer. The user is
1805 * guaranteed that this function will not be re-entered or in progress
1806 * when the ldisc is closed.
1808 * Locking: Caller holds tty->termios_rwsem
1811 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1813 struct n_tty_data
*ldata
= tty
->disc_data
;
1815 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1816 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1817 ldata
->line_start
= ldata
->read_tail
;
1818 if (!L_ICANON(tty
) || !read_cnt(ldata
)) {
1819 ldata
->canon_head
= ldata
->read_tail
;
1822 set_bit((ldata
->read_head
- 1) & (N_TTY_BUF_SIZE
- 1),
1824 ldata
->canon_head
= ldata
->read_head
;
1827 ldata
->commit_head
= ldata
->read_head
;
1832 ldata
->icanon
= (L_ICANON(tty
) != 0);
1834 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1835 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1836 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1838 bitmap_zero(ldata
->char_map
, 256);
1840 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1841 set_bit('\r', ldata
->char_map
);
1843 set_bit('\n', ldata
->char_map
);
1845 if (L_ICANON(tty
)) {
1846 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1847 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1848 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1849 set_bit('\n', ldata
->char_map
);
1850 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1851 if (L_IEXTEN(tty
)) {
1852 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1853 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1854 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1856 set_bit(REPRINT_CHAR(tty
),
1861 set_bit(START_CHAR(tty
), ldata
->char_map
);
1862 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1865 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1866 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1867 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1869 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1871 ldata
->real_raw
= 0;
1874 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1875 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1876 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1877 ldata
->real_raw
= 1;
1879 ldata
->real_raw
= 0;
1882 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1883 * been stopped by STOP_CHAR(tty) before it.
1885 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1887 process_echoes(tty
);
1890 /* The termios change make the tty ready for I/O */
1891 wake_up_interruptible(&tty
->write_wait
);
1892 wake_up_interruptible(&tty
->read_wait
);
1896 * n_tty_close - close the ldisc for this tty
1899 * Called from the terminal layer when this line discipline is
1900 * being shut down, either because of a close or becsuse of a
1901 * discipline change. The function will not be called while other
1902 * ldisc methods are in progress.
1905 static void n_tty_close(struct tty_struct
*tty
)
1907 struct n_tty_data
*ldata
= tty
->disc_data
;
1910 n_tty_packet_mode_flush(tty
);
1913 tty
->disc_data
= NULL
;
1917 * n_tty_open - open an ldisc
1918 * @tty: terminal to open
1920 * Called when this line discipline is being attached to the
1921 * terminal device. Can sleep. Called serialized so that no
1922 * other events will occur in parallel. No further open will occur
1926 static int n_tty_open(struct tty_struct
*tty
)
1928 struct n_tty_data
*ldata
;
1930 /* Currently a malloc failure here can panic */
1931 ldata
= vmalloc(sizeof(*ldata
));
1935 ldata
->overrun_time
= jiffies
;
1936 mutex_init(&ldata
->atomic_read_lock
);
1937 mutex_init(&ldata
->output_lock
);
1939 tty
->disc_data
= ldata
;
1940 reset_buffer_flags(tty
->disc_data
);
1942 ldata
->canon_column
= 0;
1943 ldata
->minimum_to_wake
= 1;
1944 ldata
->num_overrun
= 0;
1948 /* indicate buffer work may resume */
1949 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1950 n_tty_set_termios(tty
, NULL
);
1951 tty_unthrottle(tty
);
1958 static inline int input_available_p(struct tty_struct
*tty
, int poll
)
1960 struct n_tty_data
*ldata
= tty
->disc_data
;
1961 int amt
= poll
&& !TIME_CHAR(tty
) && MIN_CHAR(tty
) ? MIN_CHAR(tty
) : 1;
1963 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1964 return ldata
->canon_head
!= ldata
->read_tail
;
1966 return ldata
->commit_head
- ldata
->read_tail
>= amt
;
1969 static inline int check_other_done(struct tty_struct
*tty
)
1971 int done
= test_bit(TTY_OTHER_DONE
, &tty
->flags
);
1973 /* paired with cmpxchg() in check_other_closed(); ensures
1974 * read buffer head index is not stale
1976 smp_mb__after_atomic();
1982 * copy_from_read_buf - copy read data directly
1983 * @tty: terminal device
1987 * Helper function to speed up n_tty_read. It is only called when
1988 * ICANON is off; it copies characters straight from the tty queue to
1989 * user space directly. It can be profitably called twice; once to
1990 * drain the space from the tail pointer to the (physical) end of the
1991 * buffer, and once to drain the space from the (physical) beginning of
1992 * the buffer to head pointer.
1994 * Called under the ldata->atomic_read_lock sem
1996 * n_tty_read()/consumer path:
1997 * caller holds non-exclusive termios_rwsem
1998 * read_tail published
2001 static int copy_from_read_buf(struct tty_struct
*tty
,
2002 unsigned char __user
**b
,
2006 struct n_tty_data
*ldata
= tty
->disc_data
;
2010 size_t head
= smp_load_acquire(&ldata
->commit_head
);
2011 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2014 n
= min(head
- ldata
->read_tail
, N_TTY_BUF_SIZE
- tail
);
2017 const unsigned char *from
= read_buf_addr(ldata
, tail
);
2018 retval
= copy_to_user(*b
, from
, n
);
2020 is_eof
= n
== 1 && *from
== EOF_CHAR(tty
);
2021 tty_audit_add_data(tty
, from
, n
, ldata
->icanon
);
2022 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ n
);
2023 /* Turn single EOF into zero-length read */
2024 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&&
2025 (head
== ldata
->read_tail
))
2034 * canon_copy_from_read_buf - copy read data in canonical mode
2035 * @tty: terminal device
2039 * Helper function for n_tty_read. It is only called when ICANON is on;
2040 * it copies one line of input up to and including the line-delimiting
2041 * character into the user-space buffer.
2043 * NB: When termios is changed from non-canonical to canonical mode and
2044 * the read buffer contains data, n_tty_set_termios() simulates an EOF
2045 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
2046 * This causes data already processed as input to be immediately available
2047 * as input although a newline has not been received.
2049 * Called under the atomic_read_lock mutex
2051 * n_tty_read()/consumer path:
2052 * caller holds non-exclusive termios_rwsem
2053 * read_tail published
2056 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
2057 unsigned char __user
**b
,
2060 struct n_tty_data
*ldata
= tty
->disc_data
;
2061 size_t n
, size
, more
, c
;
2066 /* N.B. avoid overrun if nr == 0 */
2070 n
= min(*nr
+ 1, smp_load_acquire(&ldata
->canon_head
) - ldata
->read_tail
);
2072 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2073 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
2075 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2076 __func__
, *nr
, tail
, n
, size
);
2078 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
2079 more
= n
- (size
- tail
);
2080 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2081 /* scan wrapped without finding set bit */
2082 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2083 found
= eol
!= more
;
2085 found
= eol
!= size
;
2088 if (n
> N_TTY_BUF_SIZE
)
2089 n
+= N_TTY_BUF_SIZE
;
2092 if (!found
|| read_buf(ldata
, eol
) != __DISABLED_CHAR
) {
2097 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu tail:%zu more:%zu\n",
2098 __func__
, eol
, found
, n
, c
, tail
, more
);
2100 ret
= tty_copy_to_user(tty
, *b
, tail
, n
);
2107 clear_bit(eol
, ldata
->read_flags
);
2108 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ c
);
2112 ldata
->line_start
= ldata
->read_tail
;
2115 tty_audit_push(tty
);
2120 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2124 * job_control - check job control
2126 * @file: file handle
2128 * Perform job control management checks on this file/tty descriptor
2129 * and if appropriate send any needed signals and return a negative
2130 * error code if action should be taken.
2132 * Locking: redirected write test is safe
2133 * current->signal->tty check is safe
2134 * ctrl_lock to safely reference tty->pgrp
2137 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2139 /* Job control check -- must be done at start and after
2140 every sleep (POSIX.1 7.1.1.4). */
2141 /* NOTE: not yet done after every sleep pending a thorough
2142 check of the logic of this change. -- jlc */
2143 /* don't stop on /dev/console */
2144 if (file
->f_op
->write
== redirected_tty_write
)
2147 return __tty_check_change(tty
, SIGTTIN
);
2152 * n_tty_read - read function for tty
2154 * @file: file object
2155 * @buf: userspace buffer pointer
2158 * Perform reads for the line discipline. We are guaranteed that the
2159 * line discipline will not be closed under us but we may get multiple
2160 * parallel readers and must handle this ourselves. We may also get
2161 * a hangup. Always called in user context, may sleep.
2163 * This code must be sure never to sleep through a hangup.
2165 * n_tty_read()/consumer path:
2166 * claims non-exclusive termios_rwsem
2167 * publishes read_tail
2170 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2171 unsigned char __user
*buf
, size_t nr
)
2173 struct n_tty_data
*ldata
= tty
->disc_data
;
2174 unsigned char __user
*b
= buf
;
2175 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2183 c
= job_control(tty
, file
);
2188 * Internal serialization of reads.
2190 if (file
->f_flags
& O_NONBLOCK
) {
2191 if (!mutex_trylock(&ldata
->atomic_read_lock
))
2194 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
))
2195 return -ERESTARTSYS
;
2198 down_read(&tty
->termios_rwsem
);
2201 timeout
= MAX_SCHEDULE_TIMEOUT
;
2202 if (!ldata
->icanon
) {
2203 minimum
= MIN_CHAR(tty
);
2205 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2207 ldata
->minimum_to_wake
= 1;
2208 else if (!waitqueue_active(&tty
->read_wait
) ||
2209 (ldata
->minimum_to_wake
> minimum
))
2210 ldata
->minimum_to_wake
= minimum
;
2212 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2213 ldata
->minimum_to_wake
= minimum
= 1;
2217 packet
= tty
->packet
;
2218 tail
= ldata
->read_tail
;
2220 add_wait_queue(&tty
->read_wait
, &wait
);
2222 /* First test for status change. */
2223 if (packet
&& tty
->link
->ctrl_status
) {
2227 spin_lock_irq(&tty
->link
->ctrl_lock
);
2228 cs
= tty
->link
->ctrl_status
;
2229 tty
->link
->ctrl_status
= 0;
2230 spin_unlock_irq(&tty
->link
->ctrl_lock
);
2231 if (tty_put_user(tty
, cs
, b
++)) {
2240 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2241 ((minimum
- (b
- buf
)) >= 1))
2242 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2244 done
= check_other_done(tty
);
2246 if (!input_available_p(tty
, 0)) {
2251 if (tty_hung_up_p(file
))
2255 if (file
->f_flags
& O_NONBLOCK
) {
2259 if (signal_pending(current
)) {
2260 retval
= -ERESTARTSYS
;
2263 up_read(&tty
->termios_rwsem
);
2265 timeout
= wait_woken(&wait
, TASK_INTERRUPTIBLE
,
2268 down_read(&tty
->termios_rwsem
);
2272 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2273 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2279 /* Deal with packet mode. */
2280 if (packet
&& b
== buf
) {
2281 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2289 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2290 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2297 n_tty_check_unthrottle(tty
);
2299 if (b
- buf
>= minimum
)
2304 if (tail
!= ldata
->read_tail
)
2305 n_tty_kick_worker(tty
);
2306 up_read(&tty
->termios_rwsem
);
2308 remove_wait_queue(&tty
->read_wait
, &wait
);
2309 if (!waitqueue_active(&tty
->read_wait
))
2310 ldata
->minimum_to_wake
= minimum
;
2312 mutex_unlock(&ldata
->atomic_read_lock
);
2321 * n_tty_write - write function for tty
2323 * @file: file object
2324 * @buf: userspace buffer pointer
2327 * Write function of the terminal device. This is serialized with
2328 * respect to other write callers but not to termios changes, reads
2329 * and other such events. Since the receive code will echo characters,
2330 * thus calling driver write methods, the output_lock is used in
2331 * the output processing functions called here as well as in the
2332 * echo processing function to protect the column state and space
2333 * left in the buffer.
2335 * This code must be sure never to sleep through a hangup.
2337 * Locking: output_lock to protect column state and space left
2338 * (note that the process_output*() functions take this
2342 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2343 const unsigned char *buf
, size_t nr
)
2345 const unsigned char *b
= buf
;
2346 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2350 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2351 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2352 retval
= tty_check_change(tty
);
2357 down_read(&tty
->termios_rwsem
);
2359 /* Write out any echoed characters that are still pending */
2360 process_echoes(tty
);
2362 add_wait_queue(&tty
->write_wait
, &wait
);
2364 if (signal_pending(current
)) {
2365 retval
= -ERESTARTSYS
;
2368 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2374 ssize_t num
= process_output_block(tty
, b
, nr
);
2386 if (process_output(c
, tty
) < 0)
2390 if (tty
->ops
->flush_chars
)
2391 tty
->ops
->flush_chars(tty
);
2393 struct n_tty_data
*ldata
= tty
->disc_data
;
2396 mutex_lock(&ldata
->output_lock
);
2397 c
= tty
->ops
->write(tty
, b
, nr
);
2398 mutex_unlock(&ldata
->output_lock
);
2411 if (file
->f_flags
& O_NONBLOCK
) {
2415 up_read(&tty
->termios_rwsem
);
2417 wait_woken(&wait
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2419 down_read(&tty
->termios_rwsem
);
2422 remove_wait_queue(&tty
->write_wait
, &wait
);
2423 if (b
- buf
!= nr
&& tty
->fasync
)
2424 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2425 up_read(&tty
->termios_rwsem
);
2426 return (b
- buf
) ? b
- buf
: retval
;
2430 * n_tty_poll - poll method for N_TTY
2431 * @tty: terminal device
2432 * @file: file accessing it
2435 * Called when the line discipline is asked to poll() for data or
2436 * for special events. This code is not serialized with respect to
2437 * other events save open/close.
2439 * This code must be sure never to sleep through a hangup.
2440 * Called without the kernel lock held - fine
2443 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2446 struct n_tty_data
*ldata
= tty
->disc_data
;
2447 unsigned int mask
= 0;
2449 poll_wait(file
, &tty
->read_wait
, wait
);
2450 poll_wait(file
, &tty
->write_wait
, wait
);
2451 if (check_other_done(tty
))
2453 if (input_available_p(tty
, 1))
2454 mask
|= POLLIN
| POLLRDNORM
;
2455 if (tty
->packet
&& tty
->link
->ctrl_status
)
2456 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2457 if (tty_hung_up_p(file
))
2459 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2460 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2461 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2463 ldata
->minimum_to_wake
= 1;
2465 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2466 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2467 tty_write_room(tty
) > 0)
2468 mask
|= POLLOUT
| POLLWRNORM
;
2472 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2474 size_t nr
, head
, tail
;
2476 if (ldata
->canon_head
== ldata
->read_tail
)
2478 head
= ldata
->canon_head
;
2479 tail
= ldata
->read_tail
;
2481 /* Skip EOF-chars.. */
2482 while (head
!= tail
) {
2483 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2484 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2491 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2492 unsigned int cmd
, unsigned long arg
)
2494 struct n_tty_data
*ldata
= tty
->disc_data
;
2499 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2501 down_write(&tty
->termios_rwsem
);
2503 retval
= inq_canon(ldata
);
2505 retval
= read_cnt(ldata
);
2506 up_write(&tty
->termios_rwsem
);
2507 return put_user(retval
, (unsigned int __user
*) arg
);
2509 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2513 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2515 struct n_tty_data
*ldata
= tty
->disc_data
;
2517 if (!waitqueue_active(&tty
->read_wait
)) {
2519 ldata
->minimum_to_wake
= 1;
2520 else if (!tty
->fasync
)
2521 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2525 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2526 .magic
= TTY_LDISC_MAGIC
,
2529 .close
= n_tty_close
,
2530 .flush_buffer
= n_tty_flush_buffer
,
2531 .chars_in_buffer
= n_tty_chars_in_buffer
,
2533 .write
= n_tty_write
,
2534 .ioctl
= n_tty_ioctl
,
2535 .set_termios
= n_tty_set_termios
,
2537 .receive_buf
= n_tty_receive_buf
,
2538 .write_wakeup
= n_tty_write_wakeup
,
2539 .fasync
= n_tty_fasync
,
2540 .receive_buf2
= n_tty_receive_buf2
,
2544 * n_tty_inherit_ops - inherit N_TTY methods
2545 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2547 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2551 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2553 *ops
= tty_ldisc_N_TTY
;
2555 ops
->refcount
= ops
->flags
= 0;
2557 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);