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 inline int tty_copy_to_user(struct tty_struct
*tty
,
170 struct n_tty_data
*ldata
= tty
->disc_data
;
172 tty_audit_add_data(tty
, to
, n
, ldata
->icanon
);
173 return copy_to_user(to
, from
, n
);
177 * n_tty_kick_worker - start input worker (if required)
180 * Re-schedules the flip buffer work if it may have stopped
182 * Caller holds exclusive termios_rwsem
184 * n_tty_read()/consumer path:
185 * holds non-exclusive termios_rwsem
188 static void n_tty_kick_worker(struct tty_struct
*tty
)
190 struct n_tty_data
*ldata
= tty
->disc_data
;
192 /* Did the input worker stop? Restart it */
193 if (unlikely(ldata
->no_room
)) {
196 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
197 "scheduling with invalid itty\n");
198 /* see if ldisc has been killed - if so, this means that
199 * even though the ldisc has been halted and ->buf.work
200 * cancelled, ->buf.work is about to be rescheduled
202 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
203 "scheduling buffer work for halted ldisc\n");
204 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
208 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
210 struct n_tty_data
*ldata
= tty
->disc_data
;
214 n
= ldata
->commit_head
- ldata
->read_tail
;
216 n
= ldata
->canon_head
- ldata
->read_tail
;
221 * n_tty_write_wakeup - asynchronous I/O notifier
224 * Required for the ptys, serial driver etc. since processes
225 * that attach themselves to the master and rely on ASYNC
226 * IO must be woken up
229 static void n_tty_write_wakeup(struct tty_struct
*tty
)
231 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
232 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
235 static void n_tty_check_throttle(struct tty_struct
*tty
)
237 struct n_tty_data
*ldata
= tty
->disc_data
;
240 * Check the remaining room for the input canonicalization
241 * mode. We don't want to throttle the driver if we're in
242 * canonical mode and don't have a newline yet!
244 if (ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
)
249 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
250 if (N_TTY_BUF_SIZE
- read_cnt(ldata
) >= TTY_THRESHOLD_THROTTLE
)
252 throttled
= tty_throttle_safe(tty
);
256 __tty_set_flow_change(tty
, 0);
259 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
261 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
262 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
263 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
267 n_tty_kick_worker(tty
);
268 n_tty_write_wakeup(tty
->link
);
269 if (waitqueue_active(&tty
->link
->write_wait
))
270 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
274 /* If there is enough space in the read buffer now, let the
275 * low-level driver know. We use chars_in_buffer() to
276 * check the buffer, as it now knows about canonical mode.
277 * Otherwise, if the driver is throttled and the line is
278 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
279 * we won't get any more characters.
284 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
285 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
289 n_tty_kick_worker(tty
);
290 unthrottled
= tty_unthrottle_safe(tty
);
294 __tty_set_flow_change(tty
, 0);
298 * put_tty_queue - add character to tty
302 * Add a character to the tty read_buf queue.
304 * n_tty_receive_buf()/producer path:
305 * caller holds non-exclusive termios_rwsem
308 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
310 *read_buf_addr(ldata
, ldata
->read_head
) = c
;
315 * reset_buffer_flags - reset buffer state
316 * @tty: terminal to reset
318 * Reset the read buffer counters and clear the flags.
319 * Called from n_tty_open() and n_tty_flush_buffer().
321 * Locking: caller holds exclusive termios_rwsem
322 * (or locking is not required)
325 static void reset_buffer_flags(struct n_tty_data
*ldata
)
327 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
328 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
329 ldata
->commit_head
= 0;
330 ldata
->echo_mark
= 0;
331 ldata
->line_start
= 0;
334 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
338 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
342 if (tty
->link
->packet
) {
343 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
344 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
345 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
346 if (waitqueue_active(&tty
->link
->read_wait
))
347 wake_up_interruptible(&tty
->link
->read_wait
);
352 * n_tty_flush_buffer - clean input queue
353 * @tty: terminal device
355 * Flush the input buffer. Called when the tty layer wants the
356 * buffer flushed (eg at hangup) or when the N_TTY line discipline
357 * internally has to clean the pending queue (for example some signals).
359 * Holds termios_rwsem to exclude producer/consumer while
360 * buffer indices are reset.
362 * Locking: ctrl_lock, exclusive termios_rwsem
365 static void n_tty_flush_buffer(struct tty_struct
*tty
)
367 down_write(&tty
->termios_rwsem
);
368 reset_buffer_flags(tty
->disc_data
);
369 n_tty_kick_worker(tty
);
372 n_tty_packet_mode_flush(tty
);
373 up_write(&tty
->termios_rwsem
);
377 * n_tty_chars_in_buffer - report available bytes
380 * Report the number of characters buffered to be delivered to user
381 * at this instant in time.
383 * Locking: exclusive termios_rwsem
386 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
390 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
392 down_write(&tty
->termios_rwsem
);
393 n
= chars_in_buffer(tty
);
394 up_write(&tty
->termios_rwsem
);
399 * is_utf8_continuation - utf8 multibyte check
402 * Returns true if the utf8 character 'c' is a multibyte continuation
403 * character. We use this to correctly compute the on screen size
404 * of the character when printing
407 static inline int is_utf8_continuation(unsigned char c
)
409 return (c
& 0xc0) == 0x80;
413 * is_continuation - multibyte check
416 * Returns true if the utf8 character 'c' is a multibyte continuation
417 * character and the terminal is in unicode mode.
420 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
422 return I_IUTF8(tty
) && is_utf8_continuation(c
);
426 * do_output_char - output one character
427 * @c: character (or partial unicode symbol)
428 * @tty: terminal device
429 * @space: space available in tty driver write buffer
431 * This is a helper function that handles one output character
432 * (including special characters like TAB, CR, LF, etc.),
433 * doing OPOST processing and putting the results in the
434 * tty driver's write buffer.
436 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
437 * and NLDLY. They simply aren't relevant in the world today.
438 * If you ever need them, add them here.
440 * Returns the number of bytes of buffer space used or -1 if
443 * Locking: should be called under the output_lock to protect
444 * the column state and space left in the buffer
447 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
449 struct n_tty_data
*ldata
= tty
->disc_data
;
462 ldata
->canon_column
= ldata
->column
= 0;
463 tty
->ops
->write(tty
, "\r\n", 2);
466 ldata
->canon_column
= ldata
->column
;
469 if (O_ONOCR(tty
) && ldata
->column
== 0)
474 ldata
->canon_column
= ldata
->column
= 0;
477 ldata
->canon_column
= ldata
->column
= 0;
480 spaces
= 8 - (ldata
->column
& 7);
481 if (O_TABDLY(tty
) == XTABS
) {
484 ldata
->column
+= spaces
;
485 tty
->ops
->write(tty
, " ", spaces
);
488 ldata
->column
+= spaces
;
491 if (ldata
->column
> 0)
498 if (!is_continuation(c
, tty
))
504 tty_put_char(tty
, c
);
509 * process_output - output post processor
510 * @c: character (or partial unicode symbol)
511 * @tty: terminal device
513 * Output one character with OPOST processing.
514 * Returns -1 when the output device is full and the character
517 * Locking: output_lock to protect column state and space left
518 * (also, this is called from n_tty_write under the
519 * tty layer write lock)
522 static int process_output(unsigned char c
, struct tty_struct
*tty
)
524 struct n_tty_data
*ldata
= tty
->disc_data
;
527 mutex_lock(&ldata
->output_lock
);
529 space
= tty_write_room(tty
);
530 retval
= do_output_char(c
, tty
, space
);
532 mutex_unlock(&ldata
->output_lock
);
540 * process_output_block - block post processor
541 * @tty: terminal device
542 * @buf: character buffer
543 * @nr: number of bytes to output
545 * Output a block of characters with OPOST processing.
546 * Returns the number of characters output.
548 * This path is used to speed up block console writes, among other
549 * things when processing blocks of output data. It handles only
550 * the simple cases normally found and helps to generate blocks of
551 * symbols for the console driver and thus improve performance.
553 * Locking: output_lock to protect column state and space left
554 * (also, this is called from n_tty_write under the
555 * tty layer write lock)
558 static ssize_t
process_output_block(struct tty_struct
*tty
,
559 const unsigned char *buf
, unsigned int nr
)
561 struct n_tty_data
*ldata
= tty
->disc_data
;
564 const unsigned char *cp
;
566 mutex_lock(&ldata
->output_lock
);
568 space
= tty_write_room(tty
);
570 mutex_unlock(&ldata
->output_lock
);
576 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
577 unsigned char c
= *cp
;
585 ldata
->canon_column
= ldata
->column
;
588 if (O_ONOCR(tty
) && ldata
->column
== 0)
592 ldata
->canon_column
= ldata
->column
= 0;
597 if (ldata
->column
> 0)
604 if (!is_continuation(c
, tty
))
611 i
= tty
->ops
->write(tty
, buf
, i
);
613 mutex_unlock(&ldata
->output_lock
);
618 * process_echoes - write pending echo characters
619 * @tty: terminal device
621 * Write previously buffered echo (and other ldisc-generated)
622 * characters to the tty.
624 * Characters generated by the ldisc (including echoes) need to
625 * be buffered because the driver's write buffer can fill during
626 * heavy program output. Echoing straight to the driver will
627 * often fail under these conditions, causing lost characters and
628 * resulting mismatches of ldisc state information.
630 * Since the ldisc state must represent the characters actually sent
631 * to the driver at the time of the write, operations like certain
632 * changes in column state are also saved in the buffer and executed
635 * A circular fifo buffer is used so that the most recent characters
636 * are prioritized. Also, when control characters are echoed with a
637 * prefixed "^", the pair is treated atomically and thus not separated.
639 * Locking: callers must hold output_lock
642 static size_t __process_echoes(struct tty_struct
*tty
)
644 struct n_tty_data
*ldata
= tty
->disc_data
;
645 int space
, old_space
;
649 old_space
= space
= tty_write_room(tty
);
651 tail
= ldata
->echo_tail
;
652 while (ldata
->echo_commit
!= tail
) {
653 c
= echo_buf(ldata
, tail
);
654 if (c
== ECHO_OP_START
) {
656 int no_space_left
= 0;
659 * If the buffer byte is the start of a multi-byte
660 * operation, get the next byte, which is either the
661 * op code or a control character value.
663 op
= echo_buf(ldata
, tail
+ 1);
666 unsigned int num_chars
, num_bs
;
668 case ECHO_OP_ERASE_TAB
:
669 num_chars
= echo_buf(ldata
, tail
+ 2);
672 * Determine how many columns to go back
673 * in order to erase the tab.
674 * This depends on the number of columns
675 * used by other characters within the tab
676 * area. If this (modulo 8) count is from
677 * the start of input rather than from a
678 * previous tab, we offset by canon column.
679 * Otherwise, tab spacing is normal.
681 if (!(num_chars
& 0x80))
682 num_chars
+= ldata
->canon_column
;
683 num_bs
= 8 - (num_chars
& 7);
685 if (num_bs
> space
) {
691 tty_put_char(tty
, '\b');
692 if (ldata
->column
> 0)
698 case ECHO_OP_SET_CANON_COL
:
699 ldata
->canon_column
= ldata
->column
;
703 case ECHO_OP_MOVE_BACK_COL
:
704 if (ldata
->column
> 0)
710 /* This is an escaped echo op start code */
715 tty_put_char(tty
, ECHO_OP_START
);
723 * If the op is not a special byte code,
724 * it is a ctrl char tagged to be echoed
725 * as "^X" (where X is the letter
726 * representing the control char).
727 * Note that we must ensure there is
728 * enough space for the whole ctrl pair.
735 tty_put_char(tty
, '^');
736 tty_put_char(tty
, op
^ 0100);
746 int retval
= do_output_char(c
, tty
, space
);
753 tty_put_char(tty
, c
);
760 /* If the echo buffer is nearly full (so that the possibility exists
761 * of echo overrun before the next commit), then discard enough
762 * data at the tail to prevent a subsequent overrun */
763 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
764 if (echo_buf(ldata
, tail
) == ECHO_OP_START
) {
765 if (echo_buf(ldata
, tail
+ 1) == ECHO_OP_ERASE_TAB
)
773 ldata
->echo_tail
= tail
;
774 return old_space
- space
;
777 static void commit_echoes(struct tty_struct
*tty
)
779 struct n_tty_data
*ldata
= tty
->disc_data
;
780 size_t nr
, old
, echoed
;
783 head
= ldata
->echo_head
;
784 ldata
->echo_mark
= head
;
785 old
= ldata
->echo_commit
- ldata
->echo_tail
;
787 /* Process committed echoes if the accumulated # of bytes
788 * is over the threshold (and try again each time another
789 * block is accumulated) */
790 nr
= head
- ldata
->echo_tail
;
791 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
794 mutex_lock(&ldata
->output_lock
);
795 ldata
->echo_commit
= head
;
796 echoed
= __process_echoes(tty
);
797 mutex_unlock(&ldata
->output_lock
);
799 if (echoed
&& tty
->ops
->flush_chars
)
800 tty
->ops
->flush_chars(tty
);
803 static void process_echoes(struct tty_struct
*tty
)
805 struct n_tty_data
*ldata
= tty
->disc_data
;
808 if (ldata
->echo_mark
== ldata
->echo_tail
)
811 mutex_lock(&ldata
->output_lock
);
812 ldata
->echo_commit
= ldata
->echo_mark
;
813 echoed
= __process_echoes(tty
);
814 mutex_unlock(&ldata
->output_lock
);
816 if (echoed
&& tty
->ops
->flush_chars
)
817 tty
->ops
->flush_chars(tty
);
820 /* NB: echo_mark and echo_head should be equivalent here */
821 static void flush_echoes(struct tty_struct
*tty
)
823 struct n_tty_data
*ldata
= tty
->disc_data
;
825 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
826 ldata
->echo_commit
== ldata
->echo_head
)
829 mutex_lock(&ldata
->output_lock
);
830 ldata
->echo_commit
= ldata
->echo_head
;
831 __process_echoes(tty
);
832 mutex_unlock(&ldata
->output_lock
);
836 * add_echo_byte - add a byte to the echo buffer
837 * @c: unicode byte to echo
840 * Add a character or operation byte to the echo buffer.
843 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
845 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
849 * echo_move_back_col - add operation to move back a column
852 * Add an operation to the echo buffer to move back one column.
855 static void echo_move_back_col(struct n_tty_data
*ldata
)
857 add_echo_byte(ECHO_OP_START
, ldata
);
858 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
862 * echo_set_canon_col - add operation to set the canon column
865 * Add an operation to the echo buffer to set the canon column
866 * to the current column.
869 static void echo_set_canon_col(struct n_tty_data
*ldata
)
871 add_echo_byte(ECHO_OP_START
, ldata
);
872 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
876 * echo_erase_tab - add operation to erase a tab
877 * @num_chars: number of character columns already used
878 * @after_tab: true if num_chars starts after a previous tab
881 * Add an operation to the echo buffer to erase a tab.
883 * Called by the eraser function, which knows how many character
884 * columns have been used since either a previous tab or the start
885 * of input. This information will be used later, along with
886 * canon column (if applicable), to go back the correct number
890 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
891 struct n_tty_data
*ldata
)
893 add_echo_byte(ECHO_OP_START
, ldata
);
894 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
896 /* We only need to know this modulo 8 (tab spacing) */
899 /* Set the high bit as a flag if num_chars is after a previous tab */
903 add_echo_byte(num_chars
, ldata
);
907 * echo_char_raw - echo a character raw
908 * @c: unicode byte to echo
909 * @tty: terminal device
911 * Echo user input back onto the screen. This must be called only when
912 * L_ECHO(tty) is true. Called from the driver receive_buf path.
914 * This variant does not treat control characters specially.
917 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
919 if (c
== ECHO_OP_START
) {
920 add_echo_byte(ECHO_OP_START
, ldata
);
921 add_echo_byte(ECHO_OP_START
, ldata
);
923 add_echo_byte(c
, ldata
);
928 * echo_char - echo a character
929 * @c: unicode byte to echo
930 * @tty: terminal device
932 * Echo user input back onto the screen. This must be called only when
933 * L_ECHO(tty) is true. Called from the driver receive_buf path.
935 * This variant tags control characters to be echoed as "^X"
936 * (where X is the letter representing the control char).
939 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
941 struct n_tty_data
*ldata
= tty
->disc_data
;
943 if (c
== ECHO_OP_START
) {
944 add_echo_byte(ECHO_OP_START
, ldata
);
945 add_echo_byte(ECHO_OP_START
, ldata
);
947 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
948 add_echo_byte(ECHO_OP_START
, ldata
);
949 add_echo_byte(c
, ldata
);
954 * finish_erasing - complete erase
958 static inline void finish_erasing(struct n_tty_data
*ldata
)
960 if (ldata
->erasing
) {
961 echo_char_raw('/', ldata
);
967 * eraser - handle erase function
968 * @c: character input
969 * @tty: terminal device
971 * Perform erase and necessary output when an erase character is
972 * present in the stream from the driver layer. Handles the complexities
973 * of UTF-8 multibyte symbols.
975 * n_tty_receive_buf()/producer path:
976 * caller holds non-exclusive termios_rwsem
979 static void eraser(unsigned char c
, struct tty_struct
*tty
)
981 struct n_tty_data
*ldata
= tty
->disc_data
;
982 enum { ERASE
, WERASE
, KILL
} kill_type
;
987 if (ldata
->read_head
== ldata
->canon_head
) {
988 /* process_output('\a', tty); */ /* what do you think? */
991 if (c
== ERASE_CHAR(tty
))
993 else if (c
== WERASE_CHAR(tty
))
997 ldata
->read_head
= ldata
->canon_head
;
1000 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1001 ldata
->read_head
= ldata
->canon_head
;
1002 finish_erasing(ldata
);
1003 echo_char(KILL_CHAR(tty
), tty
);
1004 /* Add a newline if ECHOK is on and ECHOKE is off. */
1006 echo_char_raw('\n', ldata
);
1013 while (ldata
->read_head
!= ldata
->canon_head
) {
1014 head
= ldata
->read_head
;
1016 /* erase a single possibly multibyte character */
1019 c
= read_buf(ldata
, head
);
1020 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1022 /* do not partially erase */
1023 if (is_continuation(c
, tty
))
1026 if (kill_type
== WERASE
) {
1027 /* Equivalent to BSD's ALTWERASE. */
1028 if (isalnum(c
) || c
== '_')
1030 else if (seen_alnums
)
1033 cnt
= ldata
->read_head
- head
;
1034 ldata
->read_head
= head
;
1036 if (L_ECHOPRT(tty
)) {
1037 if (!ldata
->erasing
) {
1038 echo_char_raw('\\', ldata
);
1041 /* if cnt > 1, output a multi-byte character */
1045 echo_char_raw(read_buf(ldata
, head
), ldata
);
1046 echo_move_back_col(ldata
);
1048 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1049 echo_char(ERASE_CHAR(tty
), tty
);
1050 } else if (c
== '\t') {
1051 unsigned int num_chars
= 0;
1053 size_t tail
= ldata
->read_head
;
1056 * Count the columns used for characters
1057 * since the start of input or after a
1059 * This info is used to go back the correct
1060 * number of columns.
1062 while (tail
!= ldata
->canon_head
) {
1064 c
= read_buf(ldata
, tail
);
1068 } else if (iscntrl(c
)) {
1071 } else if (!is_continuation(c
, tty
)) {
1075 echo_erase_tab(num_chars
, after_tab
, ldata
);
1077 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1078 echo_char_raw('\b', ldata
);
1079 echo_char_raw(' ', ldata
);
1080 echo_char_raw('\b', ldata
);
1082 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1083 echo_char_raw('\b', ldata
);
1084 echo_char_raw(' ', ldata
);
1085 echo_char_raw('\b', ldata
);
1089 if (kill_type
== ERASE
)
1092 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1093 finish_erasing(ldata
);
1097 * isig - handle the ISIG optio
1101 * Called when a signal is being sent due to terminal input.
1102 * Called from the driver receive_buf path so serialized.
1104 * Performs input and output flush if !NOFLSH. In this context, the echo
1105 * buffer is 'output'. The signal is processed first to alert any current
1106 * readers or writers to discontinue and exit their i/o loops.
1108 * Locking: ctrl_lock
1111 static void __isig(int sig
, struct tty_struct
*tty
)
1113 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1115 kill_pgrp(tty_pgrp
, sig
, 1);
1120 static void isig(int sig
, struct tty_struct
*tty
)
1122 struct n_tty_data
*ldata
= tty
->disc_data
;
1124 if (L_NOFLSH(tty
)) {
1128 } else { /* signal and flush */
1129 up_read(&tty
->termios_rwsem
);
1130 down_write(&tty
->termios_rwsem
);
1134 /* clear echo buffer */
1135 mutex_lock(&ldata
->output_lock
);
1136 ldata
->echo_head
= ldata
->echo_tail
= 0;
1137 ldata
->echo_mark
= ldata
->echo_commit
= 0;
1138 mutex_unlock(&ldata
->output_lock
);
1140 /* clear output buffer */
1141 tty_driver_flush_buffer(tty
);
1143 /* clear input buffer */
1144 reset_buffer_flags(tty
->disc_data
);
1146 /* notify pty master of flush */
1148 n_tty_packet_mode_flush(tty
);
1150 up_write(&tty
->termios_rwsem
);
1151 down_read(&tty
->termios_rwsem
);
1156 * n_tty_receive_break - handle break
1159 * An RS232 break event has been hit in the incoming bitstream. This
1160 * can cause a variety of events depending upon the termios settings.
1162 * n_tty_receive_buf()/producer path:
1163 * caller holds non-exclusive termios_rwsem
1165 * Note: may get exclusive termios_rwsem if flushing input buffer
1168 static void n_tty_receive_break(struct tty_struct
*tty
)
1170 struct n_tty_data
*ldata
= tty
->disc_data
;
1174 if (I_BRKINT(tty
)) {
1178 if (I_PARMRK(tty
)) {
1179 put_tty_queue('\377', ldata
);
1180 put_tty_queue('\0', ldata
);
1182 put_tty_queue('\0', ldata
);
1183 if (waitqueue_active(&tty
->read_wait
))
1184 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1188 * n_tty_receive_overrun - handle overrun reporting
1191 * Data arrived faster than we could process it. While the tty
1192 * driver has flagged this the bits that were missed are gone
1195 * Called from the receive_buf path so single threaded. Does not
1196 * need locking as num_overrun and overrun_time are function
1200 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1202 struct n_tty_data
*ldata
= tty
->disc_data
;
1204 ldata
->num_overrun
++;
1205 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1206 time_after(ldata
->overrun_time
, jiffies
)) {
1207 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1209 ldata
->num_overrun
);
1210 ldata
->overrun_time
= jiffies
;
1211 ldata
->num_overrun
= 0;
1216 * n_tty_receive_parity_error - error notifier
1217 * @tty: terminal device
1220 * Process a parity error and queue the right data to indicate
1221 * the error case if necessary.
1223 * n_tty_receive_buf()/producer path:
1224 * caller holds non-exclusive termios_rwsem
1226 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1228 struct n_tty_data
*ldata
= tty
->disc_data
;
1233 if (I_PARMRK(tty
)) {
1234 put_tty_queue('\377', ldata
);
1235 put_tty_queue('\0', ldata
);
1236 put_tty_queue(c
, ldata
);
1238 put_tty_queue('\0', ldata
);
1240 put_tty_queue(c
, ldata
);
1241 if (waitqueue_active(&tty
->read_wait
))
1242 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1246 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1255 process_echoes(tty
);
1260 * n_tty_receive_char - perform processing
1261 * @tty: terminal device
1264 * Process an individual character of input received from the driver.
1265 * This is serialized with respect to itself by the rules for the
1268 * n_tty_receive_buf()/producer path:
1269 * caller holds non-exclusive termios_rwsem
1270 * publishes canon_head if canonical mode is active
1272 * Returns 1 if LNEXT was received, else returns 0
1276 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1278 struct n_tty_data
*ldata
= tty
->disc_data
;
1281 if (c
== START_CHAR(tty
)) {
1283 process_echoes(tty
);
1286 if (c
== STOP_CHAR(tty
)) {
1293 if (c
== INTR_CHAR(tty
)) {
1294 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1296 } else if (c
== QUIT_CHAR(tty
)) {
1297 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1299 } else if (c
== SUSP_CHAR(tty
)) {
1300 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1305 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1307 process_echoes(tty
);
1315 } else if (c
== '\n' && I_INLCR(tty
))
1318 if (ldata
->icanon
) {
1319 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1320 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1325 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1328 finish_erasing(ldata
);
1329 if (L_ECHOCTL(tty
)) {
1330 echo_char_raw('^', ldata
);
1331 echo_char_raw('\b', ldata
);
1337 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1338 size_t tail
= ldata
->canon_head
;
1340 finish_erasing(ldata
);
1342 echo_char_raw('\n', ldata
);
1343 while (tail
!= ldata
->read_head
) {
1344 echo_char(read_buf(ldata
, tail
), tty
);
1351 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1352 echo_char_raw('\n', ldata
);
1355 goto handle_newline
;
1357 if (c
== EOF_CHAR(tty
)) {
1358 c
= __DISABLED_CHAR
;
1359 goto handle_newline
;
1361 if ((c
== EOL_CHAR(tty
)) ||
1362 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1364 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1367 /* Record the column of first canon char. */
1368 if (ldata
->canon_head
== ldata
->read_head
)
1369 echo_set_canon_col(ldata
);
1374 * XXX does PARMRK doubling happen for
1375 * EOL_CHAR and EOL2_CHAR?
1377 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1378 put_tty_queue(c
, ldata
);
1381 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1382 put_tty_queue(c
, ldata
);
1383 smp_store_release(&ldata
->canon_head
, ldata
->read_head
);
1384 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1385 if (waitqueue_active(&tty
->read_wait
))
1386 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1392 finish_erasing(ldata
);
1394 echo_char_raw('\n', ldata
);
1396 /* Record the column of first canon char. */
1397 if (ldata
->canon_head
== ldata
->read_head
)
1398 echo_set_canon_col(ldata
);
1404 /* PARMRK doubling check */
1405 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1406 put_tty_queue(c
, ldata
);
1408 put_tty_queue(c
, ldata
);
1413 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1415 struct n_tty_data
*ldata
= tty
->disc_data
;
1417 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1419 process_echoes(tty
);
1422 finish_erasing(ldata
);
1423 /* Record the column of first canon char. */
1424 if (ldata
->canon_head
== ldata
->read_head
)
1425 echo_set_canon_col(ldata
);
1429 /* PARMRK doubling check */
1430 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1431 put_tty_queue(c
, ldata
);
1432 put_tty_queue(c
, ldata
);
1435 static void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1437 n_tty_receive_char_inline(tty
, c
);
1441 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1443 struct n_tty_data
*ldata
= tty
->disc_data
;
1445 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1447 process_echoes(tty
);
1450 finish_erasing(ldata
);
1451 /* Record the column of first canon char. */
1452 if (ldata
->canon_head
== ldata
->read_head
)
1453 echo_set_canon_col(ldata
);
1457 put_tty_queue(c
, ldata
);
1460 static void n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1464 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1468 if (c
== STOP_CHAR(tty
))
1470 else if (c
== START_CHAR(tty
) ||
1471 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1472 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1473 c
!= SUSP_CHAR(tty
))) {
1475 process_echoes(tty
);
1481 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1485 n_tty_receive_break(tty
);
1489 n_tty_receive_parity_error(tty
, c
);
1492 n_tty_receive_overrun(tty
);
1495 printk(KERN_ERR
"%s: unknown flag %d\n",
1496 tty_name(tty
), flag
);
1502 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1504 struct n_tty_data
*ldata
= tty
->disc_data
;
1507 if (likely(flag
== TTY_NORMAL
)) {
1510 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1512 n_tty_receive_char(tty
, c
);
1514 n_tty_receive_char_flagged(tty
, c
, flag
);
1518 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1519 char *fp
, int count
)
1521 struct n_tty_data
*ldata
= tty
->disc_data
;
1524 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1525 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1526 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1527 ldata
->read_head
+= n
;
1531 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1532 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1533 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1534 ldata
->read_head
+= n
;
1538 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1539 char *fp
, int count
)
1541 struct n_tty_data
*ldata
= tty
->disc_data
;
1542 char flag
= TTY_NORMAL
;
1547 if (likely(flag
== TTY_NORMAL
))
1548 put_tty_queue(*cp
++, ldata
);
1550 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1555 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1556 char *fp
, int count
)
1558 char flag
= TTY_NORMAL
;
1563 if (likely(flag
== TTY_NORMAL
))
1564 n_tty_receive_char_closing(tty
, *cp
++);
1566 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1571 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1572 char *fp
, int count
)
1574 struct n_tty_data
*ldata
= tty
->disc_data
;
1575 char flag
= TTY_NORMAL
;
1580 if (likely(flag
== TTY_NORMAL
)) {
1581 unsigned char c
= *cp
++;
1585 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1587 if (L_EXTPROC(tty
)) {
1588 put_tty_queue(c
, ldata
);
1591 if (!test_bit(c
, ldata
->char_map
))
1592 n_tty_receive_char_inline(tty
, c
);
1593 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1596 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1600 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1605 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1606 char *fp
, int count
)
1608 struct n_tty_data
*ldata
= tty
->disc_data
;
1609 char flag
= TTY_NORMAL
;
1614 if (likely(flag
== TTY_NORMAL
)) {
1615 unsigned char c
= *cp
++;
1617 if (!test_bit(c
, ldata
->char_map
))
1618 n_tty_receive_char_fast(tty
, c
);
1619 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1622 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1626 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1630 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1631 char *fp
, int count
)
1633 struct n_tty_data
*ldata
= tty
->disc_data
;
1634 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1636 if (ldata
->real_raw
)
1637 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1638 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1639 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1640 else if (tty
->closing
&& !L_EXTPROC(tty
))
1641 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1644 char flag
= TTY_NORMAL
;
1648 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1652 if (!preops
&& !I_PARMRK(tty
))
1653 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1655 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1658 if (tty
->ops
->flush_chars
)
1659 tty
->ops
->flush_chars(tty
);
1662 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1665 /* publish read_head to consumer */
1666 smp_store_release(&ldata
->commit_head
, ldata
->read_head
);
1668 if ((read_cnt(ldata
) >= ldata
->minimum_to_wake
) || L_EXTPROC(tty
)) {
1669 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1670 if (waitqueue_active(&tty
->read_wait
))
1671 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1676 * n_tty_receive_buf_common - process input
1677 * @tty: device to receive input
1679 * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
1680 * @count: number of input chars in @cp
1682 * Called by the terminal driver when a block of characters has
1683 * been received. This function must be called from soft contexts
1684 * not from interrupt context. The driver is responsible for making
1685 * calls one at a time and in order (or using flush_to_ldisc)
1687 * Returns the # of input chars from @cp which were processed.
1689 * In canonical mode, the maximum line length is 4096 chars (including
1690 * the line termination char); lines longer than 4096 chars are
1691 * truncated. After 4095 chars, input data is still processed but
1692 * not stored. Overflow processing ensures the tty can always
1693 * receive more input until at least one line can be read.
1695 * In non-canonical mode, the read buffer will only accept 4095 chars;
1696 * this provides the necessary space for a newline char if the input
1697 * mode is switched to canonical.
1699 * Note it is possible for the read buffer to _contain_ 4096 chars
1700 * in non-canonical mode: the read buffer could already contain the
1701 * maximum canon line of 4096 chars when the mode is switched to
1704 * n_tty_receive_buf()/producer path:
1705 * claims non-exclusive termios_rwsem
1706 * publishes commit_head or canon_head
1709 n_tty_receive_buf_common(struct tty_struct
*tty
, const unsigned char *cp
,
1710 char *fp
, int count
, int flow
)
1712 struct n_tty_data
*ldata
= tty
->disc_data
;
1713 int room
, n
, rcvd
= 0, overflow
;
1715 down_read(&tty
->termios_rwsem
);
1719 * When PARMRK is set, each input char may take up to 3 chars
1720 * in the read buf; reduce the buffer space avail by 3x
1722 * If we are doing input canonicalization, and there are no
1723 * pending newlines, let characters through without limit, so
1724 * that erase characters will be handled. Other excess
1725 * characters will be beeped.
1727 * paired with store in *_copy_from_read_buf() -- guarantees
1728 * the consumer has loaded the data in read_buf up to the new
1729 * read_tail (so this producer will not overwrite unread data)
1731 size_t tail
= smp_load_acquire(&ldata
->read_tail
);
1733 room
= N_TTY_BUF_SIZE
- (ldata
->read_head
- tail
);
1735 room
= (room
+ 2) / 3;
1738 overflow
= ldata
->icanon
&& ldata
->canon_head
== tail
;
1739 if (overflow
&& room
< 0)
1742 ldata
->no_room
= flow
&& !room
;
1746 n
= min(count
, room
);
1750 /* ignore parity errors if handling overflow */
1751 if (!overflow
|| !fp
|| *fp
!= TTY_PARITY
)
1752 __receive_buf(tty
, cp
, fp
, n
);
1761 tty
->receive_room
= room
;
1763 /* Unthrottle if handling overflow on pty */
1764 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
) {
1766 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
1767 tty_unthrottle_safe(tty
);
1768 __tty_set_flow_change(tty
, 0);
1771 n_tty_check_throttle(tty
);
1773 up_read(&tty
->termios_rwsem
);
1778 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1779 char *fp
, int count
)
1781 n_tty_receive_buf_common(tty
, cp
, fp
, count
, 0);
1784 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1785 char *fp
, int count
)
1787 return n_tty_receive_buf_common(tty
, cp
, fp
, count
, 1);
1790 int is_ignored(int sig
)
1792 return (sigismember(¤t
->blocked
, sig
) ||
1793 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1797 * n_tty_set_termios - termios data changed
1799 * @old: previous data
1801 * Called by the tty layer when the user changes termios flags so
1802 * that the line discipline can plan ahead. This function cannot sleep
1803 * and is protected from re-entry by the tty layer. The user is
1804 * guaranteed that this function will not be re-entered or in progress
1805 * when the ldisc is closed.
1807 * Locking: Caller holds tty->termios_rwsem
1810 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1812 struct n_tty_data
*ldata
= tty
->disc_data
;
1814 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1815 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1816 ldata
->line_start
= ldata
->read_tail
;
1817 if (!L_ICANON(tty
) || !read_cnt(ldata
)) {
1818 ldata
->canon_head
= ldata
->read_tail
;
1821 set_bit((ldata
->read_head
- 1) & (N_TTY_BUF_SIZE
- 1),
1823 ldata
->canon_head
= ldata
->read_head
;
1826 ldata
->commit_head
= ldata
->read_head
;
1831 ldata
->icanon
= (L_ICANON(tty
) != 0);
1833 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1834 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1835 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1837 bitmap_zero(ldata
->char_map
, 256);
1839 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1840 set_bit('\r', ldata
->char_map
);
1842 set_bit('\n', ldata
->char_map
);
1844 if (L_ICANON(tty
)) {
1845 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1846 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1847 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1848 set_bit('\n', ldata
->char_map
);
1849 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1850 if (L_IEXTEN(tty
)) {
1851 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1852 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1853 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1855 set_bit(REPRINT_CHAR(tty
),
1860 set_bit(START_CHAR(tty
), ldata
->char_map
);
1861 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1864 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1865 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1866 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1868 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1870 ldata
->real_raw
= 0;
1873 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1874 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1875 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1876 ldata
->real_raw
= 1;
1878 ldata
->real_raw
= 0;
1881 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1882 * been stopped by STOP_CHAR(tty) before it.
1884 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1886 process_echoes(tty
);
1889 /* The termios change make the tty ready for I/O */
1890 if (waitqueue_active(&tty
->write_wait
))
1891 wake_up_interruptible(&tty
->write_wait
);
1892 if (waitqueue_active(&tty
->read_wait
))
1893 wake_up_interruptible(&tty
->read_wait
);
1897 * n_tty_close - close the ldisc for this tty
1900 * Called from the terminal layer when this line discipline is
1901 * being shut down, either because of a close or becsuse of a
1902 * discipline change. The function will not be called while other
1903 * ldisc methods are in progress.
1906 static void n_tty_close(struct tty_struct
*tty
)
1908 struct n_tty_data
*ldata
= tty
->disc_data
;
1911 n_tty_packet_mode_flush(tty
);
1914 tty
->disc_data
= NULL
;
1918 * n_tty_open - open an ldisc
1919 * @tty: terminal to open
1921 * Called when this line discipline is being attached to the
1922 * terminal device. Can sleep. Called serialized so that no
1923 * other events will occur in parallel. No further open will occur
1927 static int n_tty_open(struct tty_struct
*tty
)
1929 struct n_tty_data
*ldata
;
1931 /* Currently a malloc failure here can panic */
1932 ldata
= vmalloc(sizeof(*ldata
));
1936 ldata
->overrun_time
= jiffies
;
1937 mutex_init(&ldata
->atomic_read_lock
);
1938 mutex_init(&ldata
->output_lock
);
1940 tty
->disc_data
= ldata
;
1941 reset_buffer_flags(tty
->disc_data
);
1943 ldata
->canon_column
= 0;
1944 ldata
->minimum_to_wake
= 1;
1945 ldata
->num_overrun
= 0;
1949 /* indicate buffer work may resume */
1950 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1951 n_tty_set_termios(tty
, NULL
);
1952 tty_unthrottle(tty
);
1959 static inline int input_available_p(struct tty_struct
*tty
, int poll
)
1961 struct n_tty_data
*ldata
= tty
->disc_data
;
1962 int amt
= poll
&& !TIME_CHAR(tty
) && MIN_CHAR(tty
) ? MIN_CHAR(tty
) : 1;
1964 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1965 return ldata
->canon_head
!= ldata
->read_tail
;
1967 return ldata
->commit_head
- ldata
->read_tail
>= amt
;
1970 static inline int check_other_done(struct tty_struct
*tty
)
1972 int done
= test_bit(TTY_OTHER_DONE
, &tty
->flags
);
1974 /* paired with cmpxchg() in check_other_closed(); ensures
1975 * read buffer head index is not stale
1977 smp_mb__after_atomic();
1983 * copy_from_read_buf - copy read data directly
1984 * @tty: terminal device
1988 * Helper function to speed up n_tty_read. It is only called when
1989 * ICANON is off; it copies characters straight from the tty queue to
1990 * user space directly. It can be profitably called twice; once to
1991 * drain the space from the tail pointer to the (physical) end of the
1992 * buffer, and once to drain the space from the (physical) beginning of
1993 * the buffer to head pointer.
1995 * Called under the ldata->atomic_read_lock sem
1997 * n_tty_read()/consumer path:
1998 * caller holds non-exclusive termios_rwsem
1999 * read_tail published
2002 static int copy_from_read_buf(struct tty_struct
*tty
,
2003 unsigned char __user
**b
,
2007 struct n_tty_data
*ldata
= tty
->disc_data
;
2011 size_t head
= smp_load_acquire(&ldata
->commit_head
);
2012 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2015 n
= min(head
- ldata
->read_tail
, N_TTY_BUF_SIZE
- tail
);
2018 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2020 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
2021 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
2023 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ n
);
2024 /* Turn single EOF into zero-length read */
2025 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&&
2026 (head
== ldata
->read_tail
))
2035 * canon_copy_from_read_buf - copy read data in canonical mode
2036 * @tty: terminal device
2040 * Helper function for n_tty_read. It is only called when ICANON is on;
2041 * it copies one line of input up to and including the line-delimiting
2042 * character into the user-space buffer.
2044 * NB: When termios is changed from non-canonical to canonical mode and
2045 * the read buffer contains data, n_tty_set_termios() simulates an EOF
2046 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
2047 * This causes data already processed as input to be immediately available
2048 * as input although a newline has not been received.
2050 * Called under the atomic_read_lock mutex
2052 * n_tty_read()/consumer path:
2053 * caller holds non-exclusive termios_rwsem
2054 * read_tail published
2057 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
2058 unsigned char __user
**b
,
2061 struct n_tty_data
*ldata
= tty
->disc_data
;
2062 size_t n
, size
, more
, c
;
2068 /* N.B. avoid overrun if nr == 0 */
2069 n
= min(*nr
, smp_load_acquire(&ldata
->canon_head
) - ldata
->read_tail
);
2073 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2074 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
2076 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2077 __func__
, *nr
, tail
, n
, size
);
2079 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
2080 more
= n
- (size
- tail
);
2081 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2082 /* scan wrapped without finding set bit */
2083 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2086 } else if (eol
!= size
)
2089 size
= N_TTY_BUF_SIZE
- tail
;
2091 if (n
> N_TTY_BUF_SIZE
)
2092 n
+= N_TTY_BUF_SIZE
;
2096 if (found
&& !ldata
->push
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
2098 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
2101 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2102 __func__
, eol
, found
, n
, c
, size
, more
);
2105 ret
= tty_copy_to_user(tty
, *b
, read_buf_addr(ldata
, tail
), size
);
2108 ret
= tty_copy_to_user(tty
, *b
+ size
, ldata
->read_buf
, n
- size
);
2110 ret
= tty_copy_to_user(tty
, *b
, read_buf_addr(ldata
, tail
), n
);
2118 clear_bit(eol
, ldata
->read_flags
);
2119 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ c
);
2123 ldata
->line_start
= ldata
->read_tail
;
2126 tty_audit_push(tty
);
2128 return eof_push
? -EAGAIN
: 0;
2131 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2135 * job_control - check job control
2137 * @file: file handle
2139 * Perform job control management checks on this file/tty descriptor
2140 * and if appropriate send any needed signals and return a negative
2141 * error code if action should be taken.
2143 * Locking: redirected write test is safe
2144 * current->signal->tty check is safe
2145 * ctrl_lock to safely reference tty->pgrp
2148 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2152 /* Job control check -- must be done at start and after
2153 every sleep (POSIX.1 7.1.1.4). */
2154 /* NOTE: not yet done after every sleep pending a thorough
2155 check of the logic of this change. -- jlc */
2156 /* don't stop on /dev/console */
2157 if (file
->f_op
->write
== redirected_tty_write
||
2158 current
->signal
->tty
!= tty
)
2162 pgrp
= task_pgrp(current
);
2164 spin_lock_irq(&tty
->ctrl_lock
);
2166 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2167 else if (pgrp
!= tty
->pgrp
) {
2168 spin_unlock_irq(&tty
->ctrl_lock
);
2169 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned()) {
2173 kill_pgrp(pgrp
, SIGTTIN
, 1);
2175 set_thread_flag(TIF_SIGPENDING
);
2176 return -ERESTARTSYS
;
2178 spin_unlock_irq(&tty
->ctrl_lock
);
2185 * n_tty_read - read function for tty
2187 * @file: file object
2188 * @buf: userspace buffer pointer
2191 * Perform reads for the line discipline. We are guaranteed that the
2192 * line discipline will not be closed under us but we may get multiple
2193 * parallel readers and must handle this ourselves. We may also get
2194 * a hangup. Always called in user context, may sleep.
2196 * This code must be sure never to sleep through a hangup.
2198 * n_tty_read()/consumer path:
2199 * claims non-exclusive termios_rwsem
2200 * publishes read_tail
2203 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2204 unsigned char __user
*buf
, size_t nr
)
2206 struct n_tty_data
*ldata
= tty
->disc_data
;
2207 unsigned char __user
*b
= buf
;
2208 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2216 c
= job_control(tty
, file
);
2221 * Internal serialization of reads.
2223 if (file
->f_flags
& O_NONBLOCK
) {
2224 if (!mutex_trylock(&ldata
->atomic_read_lock
))
2227 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
))
2228 return -ERESTARTSYS
;
2231 down_read(&tty
->termios_rwsem
);
2234 timeout
= MAX_SCHEDULE_TIMEOUT
;
2235 if (!ldata
->icanon
) {
2236 minimum
= MIN_CHAR(tty
);
2238 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2240 ldata
->minimum_to_wake
= 1;
2241 else if (!waitqueue_active(&tty
->read_wait
) ||
2242 (ldata
->minimum_to_wake
> minimum
))
2243 ldata
->minimum_to_wake
= minimum
;
2245 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2246 ldata
->minimum_to_wake
= minimum
= 1;
2250 packet
= tty
->packet
;
2251 tail
= ldata
->read_tail
;
2253 add_wait_queue(&tty
->read_wait
, &wait
);
2255 /* First test for status change. */
2256 if (packet
&& tty
->link
->ctrl_status
) {
2260 spin_lock_irq(&tty
->link
->ctrl_lock
);
2261 cs
= tty
->link
->ctrl_status
;
2262 tty
->link
->ctrl_status
= 0;
2263 spin_unlock_irq(&tty
->link
->ctrl_lock
);
2264 if (tty_put_user(tty
, cs
, b
++)) {
2273 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2274 ((minimum
- (b
- buf
)) >= 1))
2275 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2277 done
= check_other_done(tty
);
2279 if (!input_available_p(tty
, 0)) {
2284 if (tty_hung_up_p(file
))
2288 if (file
->f_flags
& O_NONBLOCK
) {
2292 if (signal_pending(current
)) {
2293 retval
= -ERESTARTSYS
;
2296 up_read(&tty
->termios_rwsem
);
2298 timeout
= wait_woken(&wait
, TASK_INTERRUPTIBLE
,
2301 down_read(&tty
->termios_rwsem
);
2305 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2306 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2307 if (retval
== -EAGAIN
) {
2315 /* Deal with packet mode. */
2316 if (packet
&& b
== buf
) {
2317 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2325 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2326 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2333 n_tty_check_unthrottle(tty
);
2335 if (b
- buf
>= minimum
)
2340 if (tail
!= ldata
->read_tail
)
2341 n_tty_kick_worker(tty
);
2342 up_read(&tty
->termios_rwsem
);
2344 remove_wait_queue(&tty
->read_wait
, &wait
);
2345 if (!waitqueue_active(&tty
->read_wait
))
2346 ldata
->minimum_to_wake
= minimum
;
2348 mutex_unlock(&ldata
->atomic_read_lock
);
2357 * n_tty_write - write function for tty
2359 * @file: file object
2360 * @buf: userspace buffer pointer
2363 * Write function of the terminal device. This is serialized with
2364 * respect to other write callers but not to termios changes, reads
2365 * and other such events. Since the receive code will echo characters,
2366 * thus calling driver write methods, the output_lock is used in
2367 * the output processing functions called here as well as in the
2368 * echo processing function to protect the column state and space
2369 * left in the buffer.
2371 * This code must be sure never to sleep through a hangup.
2373 * Locking: output_lock to protect column state and space left
2374 * (note that the process_output*() functions take this
2378 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2379 const unsigned char *buf
, size_t nr
)
2381 const unsigned char *b
= buf
;
2382 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2386 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2387 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2388 retval
= tty_check_change(tty
);
2393 down_read(&tty
->termios_rwsem
);
2395 /* Write out any echoed characters that are still pending */
2396 process_echoes(tty
);
2398 add_wait_queue(&tty
->write_wait
, &wait
);
2400 if (signal_pending(current
)) {
2401 retval
= -ERESTARTSYS
;
2404 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2410 ssize_t num
= process_output_block(tty
, b
, nr
);
2422 if (process_output(c
, tty
) < 0)
2426 if (tty
->ops
->flush_chars
)
2427 tty
->ops
->flush_chars(tty
);
2429 struct n_tty_data
*ldata
= tty
->disc_data
;
2432 mutex_lock(&ldata
->output_lock
);
2433 c
= tty
->ops
->write(tty
, b
, nr
);
2434 mutex_unlock(&ldata
->output_lock
);
2447 if (file
->f_flags
& O_NONBLOCK
) {
2451 up_read(&tty
->termios_rwsem
);
2453 wait_woken(&wait
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2455 down_read(&tty
->termios_rwsem
);
2458 remove_wait_queue(&tty
->write_wait
, &wait
);
2459 if (b
- buf
!= nr
&& tty
->fasync
)
2460 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2461 up_read(&tty
->termios_rwsem
);
2462 return (b
- buf
) ? b
- buf
: retval
;
2466 * n_tty_poll - poll method for N_TTY
2467 * @tty: terminal device
2468 * @file: file accessing it
2471 * Called when the line discipline is asked to poll() for data or
2472 * for special events. This code is not serialized with respect to
2473 * other events save open/close.
2475 * This code must be sure never to sleep through a hangup.
2476 * Called without the kernel lock held - fine
2479 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2482 struct n_tty_data
*ldata
= tty
->disc_data
;
2483 unsigned int mask
= 0;
2485 poll_wait(file
, &tty
->read_wait
, wait
);
2486 poll_wait(file
, &tty
->write_wait
, wait
);
2487 if (check_other_done(tty
))
2489 if (input_available_p(tty
, 1))
2490 mask
|= POLLIN
| POLLRDNORM
;
2491 if (tty
->packet
&& tty
->link
->ctrl_status
)
2492 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2493 if (tty_hung_up_p(file
))
2495 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2496 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2497 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2499 ldata
->minimum_to_wake
= 1;
2501 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2502 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2503 tty_write_room(tty
) > 0)
2504 mask
|= POLLOUT
| POLLWRNORM
;
2508 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2510 size_t nr
, head
, tail
;
2512 if (ldata
->canon_head
== ldata
->read_tail
)
2514 head
= ldata
->canon_head
;
2515 tail
= ldata
->read_tail
;
2517 /* Skip EOF-chars.. */
2518 while (head
!= tail
) {
2519 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2520 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2527 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2528 unsigned int cmd
, unsigned long arg
)
2530 struct n_tty_data
*ldata
= tty
->disc_data
;
2535 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2537 down_write(&tty
->termios_rwsem
);
2539 retval
= inq_canon(ldata
);
2541 retval
= read_cnt(ldata
);
2542 up_write(&tty
->termios_rwsem
);
2543 return put_user(retval
, (unsigned int __user
*) arg
);
2545 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2549 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2551 struct n_tty_data
*ldata
= tty
->disc_data
;
2553 if (!waitqueue_active(&tty
->read_wait
)) {
2555 ldata
->minimum_to_wake
= 1;
2556 else if (!tty
->fasync
)
2557 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2561 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2562 .magic
= TTY_LDISC_MAGIC
,
2565 .close
= n_tty_close
,
2566 .flush_buffer
= n_tty_flush_buffer
,
2567 .chars_in_buffer
= n_tty_chars_in_buffer
,
2569 .write
= n_tty_write
,
2570 .ioctl
= n_tty_ioctl
,
2571 .set_termios
= n_tty_set_termios
,
2573 .receive_buf
= n_tty_receive_buf
,
2574 .write_wakeup
= n_tty_write_wakeup
,
2575 .fasync
= n_tty_fasync
,
2576 .receive_buf2
= n_tty_receive_buf2
,
2580 * n_tty_inherit_ops - inherit N_TTY methods
2581 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2583 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2587 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2589 *ops
= tty_ldisc_N_TTY
;
2591 ops
->refcount
= ops
->flags
= 0;
2593 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);