2 * n_tty.c --- implements the N_TTY line discipline.
4 * This code used to be in tty_io.c, but things are getting hairy
5 * enough that it made sense to split things off. (The N_TTY
6 * processing has changed so much that it's hardly recognizable,
9 * Note that the open routine for N_TTY is guaranteed never to return
10 * an error. This is because Linux will fall back to setting a line
11 * to N_TTY if it can not switch to any other line discipline.
13 * Written by Theodore Ts'o, Copyright 1994.
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18 * This file may be redistributed under the terms of the GNU General Public
21 * Reduced memory usage for older ARM systems - Russell King.
23 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
24 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25 * who actually finally proved there really was a race.
27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29 * Also fixed a bug in BLOCKING mode where n_tty_write returns
33 #include <linux/types.h>
34 #include <linux/major.h>
35 #include <linux/errno.h>
36 #include <linux/signal.h>
37 #include <linux/fcntl.h>
38 #include <linux/sched.h>
39 #include <linux/interrupt.h>
40 #include <linux/tty.h>
41 #include <linux/timer.h>
42 #include <linux/ctype.h>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
48 #include <linux/audit.h>
49 #include <linux/file.h>
50 #include <linux/uaccess.h>
51 #include <linux/module.h>
52 #include <linux/ratelimit.h>
53 #include <linux/vmalloc.h>
56 /* number of characters left in xmit buffer before select has we have room */
57 #define WAKEUP_CHARS 256
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
64 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65 #define TTY_THRESHOLD_UNTHROTTLE 128
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
73 #define ECHO_OP_START 0xff
74 #define ECHO_OP_MOVE_BACK_COL 0x80
75 #define ECHO_OP_SET_CANON_COL 0x81
76 #define ECHO_OP_ERASE_TAB 0x82
78 #define ECHO_COMMIT_WATERMARK 256
79 #define ECHO_BLOCK 256
80 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
85 # define n_tty_trace(f, args...) trace_printk(f, ##args)
87 # define n_tty_trace(f, args...)
91 /* producer-published */
98 DECLARE_BITMAP(char_map
, 256);
100 /* private to n_tty_receive_overrun (single-threaded) */
101 unsigned long overrun_time
;
107 /* must hold exclusive termios_rwsem to reset these */
108 unsigned char lnext
:1, erasing
:1, raw
:1, real_raw
:1, icanon
:1;
109 unsigned char push
:1;
111 /* shared by producer and consumer */
112 char read_buf
[N_TTY_BUF_SIZE
];
113 DECLARE_BITMAP(read_flags
, N_TTY_BUF_SIZE
);
114 unsigned char echo_buf
[N_TTY_BUF_SIZE
];
118 /* consumer-published */
122 /* protected by output lock */
124 unsigned int canon_column
;
127 struct mutex atomic_read_lock
;
128 struct mutex output_lock
;
131 static inline size_t read_cnt(struct n_tty_data
*ldata
)
133 return ldata
->read_head
- ldata
->read_tail
;
136 static inline unsigned char read_buf(struct n_tty_data
*ldata
, size_t i
)
138 return ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
141 static inline unsigned char *read_buf_addr(struct n_tty_data
*ldata
, size_t i
)
143 return &ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
146 static inline unsigned char echo_buf(struct n_tty_data
*ldata
, size_t i
)
148 return ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
151 static inline unsigned char *echo_buf_addr(struct n_tty_data
*ldata
, size_t i
)
153 return &ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
156 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
157 unsigned char __user
*ptr
)
159 struct n_tty_data
*ldata
= tty
->disc_data
;
161 tty_audit_add_data(tty
, &x
, 1, ldata
->icanon
);
162 return put_user(x
, ptr
);
166 * n_tty_kick_worker - start input worker (if required)
169 * Re-schedules the flip buffer work if it may have stopped
171 * Caller holds exclusive termios_rwsem
173 * n_tty_read()/consumer path:
174 * holds non-exclusive termios_rwsem
177 static void n_tty_kick_worker(struct tty_struct
*tty
)
179 struct n_tty_data
*ldata
= tty
->disc_data
;
181 /* Did the input worker stop? Restart it */
182 if (unlikely(ldata
->no_room
)) {
185 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
186 "scheduling with invalid itty\n");
187 /* see if ldisc has been killed - if so, this means that
188 * even though the ldisc has been halted and ->buf.work
189 * cancelled, ->buf.work is about to be rescheduled
191 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
192 "scheduling buffer work for halted ldisc\n");
193 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
197 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
199 struct n_tty_data
*ldata
= tty
->disc_data
;
203 n
= ldata
->commit_head
- ldata
->read_tail
;
205 n
= ldata
->canon_head
- ldata
->read_tail
;
210 * n_tty_write_wakeup - asynchronous I/O notifier
213 * Required for the ptys, serial driver etc. since processes
214 * that attach themselves to the master and rely on ASYNC
215 * IO must be woken up
218 static void n_tty_write_wakeup(struct tty_struct
*tty
)
220 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
221 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
224 static void n_tty_check_throttle(struct tty_struct
*tty
)
226 struct n_tty_data
*ldata
= tty
->disc_data
;
229 * Check the remaining room for the input canonicalization
230 * mode. We don't want to throttle the driver if we're in
231 * canonical mode and don't have a newline yet!
233 if (ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
)
238 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
239 if (N_TTY_BUF_SIZE
- read_cnt(ldata
) >= TTY_THRESHOLD_THROTTLE
)
241 throttled
= tty_throttle_safe(tty
);
245 __tty_set_flow_change(tty
, 0);
248 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
250 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
251 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
252 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
256 n_tty_kick_worker(tty
);
257 n_tty_write_wakeup(tty
->link
);
258 if (waitqueue_active(&tty
->link
->write_wait
))
259 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
263 /* If there is enough space in the read buffer now, let the
264 * low-level driver know. We use chars_in_buffer() to
265 * check the buffer, as it now knows about canonical mode.
266 * Otherwise, if the driver is throttled and the line is
267 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
268 * we won't get any more characters.
273 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
274 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
278 n_tty_kick_worker(tty
);
279 unthrottled
= tty_unthrottle_safe(tty
);
283 __tty_set_flow_change(tty
, 0);
287 * put_tty_queue - add character to tty
291 * Add a character to the tty read_buf queue.
293 * n_tty_receive_buf()/producer path:
294 * caller holds non-exclusive termios_rwsem
297 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
299 *read_buf_addr(ldata
, ldata
->read_head
) = c
;
304 * reset_buffer_flags - reset buffer state
305 * @tty: terminal to reset
307 * Reset the read buffer counters and clear the flags.
308 * Called from n_tty_open() and n_tty_flush_buffer().
310 * Locking: caller holds exclusive termios_rwsem
311 * (or locking is not required)
314 static void reset_buffer_flags(struct n_tty_data
*ldata
)
316 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
317 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
318 ldata
->commit_head
= 0;
319 ldata
->echo_mark
= 0;
320 ldata
->line_start
= 0;
323 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
327 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
331 if (tty
->link
->packet
) {
332 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
333 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
334 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
335 if (waitqueue_active(&tty
->link
->read_wait
))
336 wake_up_interruptible(&tty
->link
->read_wait
);
341 * n_tty_flush_buffer - clean input queue
342 * @tty: terminal device
344 * Flush the input buffer. Called when the tty layer wants the
345 * buffer flushed (eg at hangup) or when the N_TTY line discipline
346 * internally has to clean the pending queue (for example some signals).
348 * Holds termios_rwsem to exclude producer/consumer while
349 * buffer indices are reset.
351 * Locking: ctrl_lock, exclusive termios_rwsem
354 static void n_tty_flush_buffer(struct tty_struct
*tty
)
356 down_write(&tty
->termios_rwsem
);
357 reset_buffer_flags(tty
->disc_data
);
358 n_tty_kick_worker(tty
);
361 n_tty_packet_mode_flush(tty
);
362 up_write(&tty
->termios_rwsem
);
366 * n_tty_chars_in_buffer - report available bytes
369 * Report the number of characters buffered to be delivered to user
370 * at this instant in time.
372 * Locking: exclusive termios_rwsem
375 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
379 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
381 down_write(&tty
->termios_rwsem
);
382 n
= chars_in_buffer(tty
);
383 up_write(&tty
->termios_rwsem
);
388 * is_utf8_continuation - utf8 multibyte check
391 * Returns true if the utf8 character 'c' is a multibyte continuation
392 * character. We use this to correctly compute the on screen size
393 * of the character when printing
396 static inline int is_utf8_continuation(unsigned char c
)
398 return (c
& 0xc0) == 0x80;
402 * is_continuation - multibyte check
405 * Returns true if the utf8 character 'c' is a multibyte continuation
406 * character and the terminal is in unicode mode.
409 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
411 return I_IUTF8(tty
) && is_utf8_continuation(c
);
415 * do_output_char - output one character
416 * @c: character (or partial unicode symbol)
417 * @tty: terminal device
418 * @space: space available in tty driver write buffer
420 * This is a helper function that handles one output character
421 * (including special characters like TAB, CR, LF, etc.),
422 * doing OPOST processing and putting the results in the
423 * tty driver's write buffer.
425 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
426 * and NLDLY. They simply aren't relevant in the world today.
427 * If you ever need them, add them here.
429 * Returns the number of bytes of buffer space used or -1 if
432 * Locking: should be called under the output_lock to protect
433 * the column state and space left in the buffer
436 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
438 struct n_tty_data
*ldata
= tty
->disc_data
;
451 ldata
->canon_column
= ldata
->column
= 0;
452 tty
->ops
->write(tty
, "\r\n", 2);
455 ldata
->canon_column
= ldata
->column
;
458 if (O_ONOCR(tty
) && ldata
->column
== 0)
463 ldata
->canon_column
= ldata
->column
= 0;
466 ldata
->canon_column
= ldata
->column
= 0;
469 spaces
= 8 - (ldata
->column
& 7);
470 if (O_TABDLY(tty
) == XTABS
) {
473 ldata
->column
+= spaces
;
474 tty
->ops
->write(tty
, " ", spaces
);
477 ldata
->column
+= spaces
;
480 if (ldata
->column
> 0)
487 if (!is_continuation(c
, tty
))
493 tty_put_char(tty
, c
);
498 * process_output - output post processor
499 * @c: character (or partial unicode symbol)
500 * @tty: terminal device
502 * Output one character with OPOST processing.
503 * Returns -1 when the output device is full and the character
506 * Locking: output_lock to protect column state and space left
507 * (also, this is called from n_tty_write under the
508 * tty layer write lock)
511 static int process_output(unsigned char c
, struct tty_struct
*tty
)
513 struct n_tty_data
*ldata
= tty
->disc_data
;
516 mutex_lock(&ldata
->output_lock
);
518 space
= tty_write_room(tty
);
519 retval
= do_output_char(c
, tty
, space
);
521 mutex_unlock(&ldata
->output_lock
);
529 * process_output_block - block post processor
530 * @tty: terminal device
531 * @buf: character buffer
532 * @nr: number of bytes to output
534 * Output a block of characters with OPOST processing.
535 * Returns the number of characters output.
537 * This path is used to speed up block console writes, among other
538 * things when processing blocks of output data. It handles only
539 * the simple cases normally found and helps to generate blocks of
540 * symbols for the console driver and thus improve performance.
542 * Locking: output_lock to protect column state and space left
543 * (also, this is called from n_tty_write under the
544 * tty layer write lock)
547 static ssize_t
process_output_block(struct tty_struct
*tty
,
548 const unsigned char *buf
, unsigned int nr
)
550 struct n_tty_data
*ldata
= tty
->disc_data
;
553 const unsigned char *cp
;
555 mutex_lock(&ldata
->output_lock
);
557 space
= tty_write_room(tty
);
559 mutex_unlock(&ldata
->output_lock
);
565 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
566 unsigned char c
= *cp
;
574 ldata
->canon_column
= ldata
->column
;
577 if (O_ONOCR(tty
) && ldata
->column
== 0)
581 ldata
->canon_column
= ldata
->column
= 0;
586 if (ldata
->column
> 0)
593 if (!is_continuation(c
, tty
))
600 i
= tty
->ops
->write(tty
, buf
, i
);
602 mutex_unlock(&ldata
->output_lock
);
607 * process_echoes - write pending echo characters
608 * @tty: terminal device
610 * Write previously buffered echo (and other ldisc-generated)
611 * characters to the tty.
613 * Characters generated by the ldisc (including echoes) need to
614 * be buffered because the driver's write buffer can fill during
615 * heavy program output. Echoing straight to the driver will
616 * often fail under these conditions, causing lost characters and
617 * resulting mismatches of ldisc state information.
619 * Since the ldisc state must represent the characters actually sent
620 * to the driver at the time of the write, operations like certain
621 * changes in column state are also saved in the buffer and executed
624 * A circular fifo buffer is used so that the most recent characters
625 * are prioritized. Also, when control characters are echoed with a
626 * prefixed "^", the pair is treated atomically and thus not separated.
628 * Locking: callers must hold output_lock
631 static size_t __process_echoes(struct tty_struct
*tty
)
633 struct n_tty_data
*ldata
= tty
->disc_data
;
634 int space
, old_space
;
638 old_space
= space
= tty_write_room(tty
);
640 tail
= ldata
->echo_tail
;
641 while (ldata
->echo_commit
!= tail
) {
642 c
= echo_buf(ldata
, tail
);
643 if (c
== ECHO_OP_START
) {
645 int no_space_left
= 0;
648 * If the buffer byte is the start of a multi-byte
649 * operation, get the next byte, which is either the
650 * op code or a control character value.
652 op
= echo_buf(ldata
, tail
+ 1);
655 unsigned int num_chars
, num_bs
;
657 case ECHO_OP_ERASE_TAB
:
658 num_chars
= echo_buf(ldata
, tail
+ 2);
661 * Determine how many columns to go back
662 * in order to erase the tab.
663 * This depends on the number of columns
664 * used by other characters within the tab
665 * area. If this (modulo 8) count is from
666 * the start of input rather than from a
667 * previous tab, we offset by canon column.
668 * Otherwise, tab spacing is normal.
670 if (!(num_chars
& 0x80))
671 num_chars
+= ldata
->canon_column
;
672 num_bs
= 8 - (num_chars
& 7);
674 if (num_bs
> space
) {
680 tty_put_char(tty
, '\b');
681 if (ldata
->column
> 0)
687 case ECHO_OP_SET_CANON_COL
:
688 ldata
->canon_column
= ldata
->column
;
692 case ECHO_OP_MOVE_BACK_COL
:
693 if (ldata
->column
> 0)
699 /* This is an escaped echo op start code */
704 tty_put_char(tty
, ECHO_OP_START
);
712 * If the op is not a special byte code,
713 * it is a ctrl char tagged to be echoed
714 * as "^X" (where X is the letter
715 * representing the control char).
716 * Note that we must ensure there is
717 * enough space for the whole ctrl pair.
724 tty_put_char(tty
, '^');
725 tty_put_char(tty
, op
^ 0100);
735 int retval
= do_output_char(c
, tty
, space
);
742 tty_put_char(tty
, c
);
749 /* If the echo buffer is nearly full (so that the possibility exists
750 * of echo overrun before the next commit), then discard enough
751 * data at the tail to prevent a subsequent overrun */
752 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
753 if (echo_buf(ldata
, tail
) == ECHO_OP_START
) {
754 if (echo_buf(ldata
, tail
+ 1) == ECHO_OP_ERASE_TAB
)
762 ldata
->echo_tail
= tail
;
763 return old_space
- space
;
766 static void commit_echoes(struct tty_struct
*tty
)
768 struct n_tty_data
*ldata
= tty
->disc_data
;
769 size_t nr
, old
, echoed
;
772 head
= ldata
->echo_head
;
773 ldata
->echo_mark
= head
;
774 old
= ldata
->echo_commit
- ldata
->echo_tail
;
776 /* Process committed echoes if the accumulated # of bytes
777 * is over the threshold (and try again each time another
778 * block is accumulated) */
779 nr
= head
- ldata
->echo_tail
;
780 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
783 mutex_lock(&ldata
->output_lock
);
784 ldata
->echo_commit
= head
;
785 echoed
= __process_echoes(tty
);
786 mutex_unlock(&ldata
->output_lock
);
788 if (echoed
&& tty
->ops
->flush_chars
)
789 tty
->ops
->flush_chars(tty
);
792 static void process_echoes(struct tty_struct
*tty
)
794 struct n_tty_data
*ldata
= tty
->disc_data
;
797 if (ldata
->echo_mark
== ldata
->echo_tail
)
800 mutex_lock(&ldata
->output_lock
);
801 ldata
->echo_commit
= ldata
->echo_mark
;
802 echoed
= __process_echoes(tty
);
803 mutex_unlock(&ldata
->output_lock
);
805 if (echoed
&& tty
->ops
->flush_chars
)
806 tty
->ops
->flush_chars(tty
);
809 /* NB: echo_mark and echo_head should be equivalent here */
810 static void flush_echoes(struct tty_struct
*tty
)
812 struct n_tty_data
*ldata
= tty
->disc_data
;
814 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
815 ldata
->echo_commit
== ldata
->echo_head
)
818 mutex_lock(&ldata
->output_lock
);
819 ldata
->echo_commit
= ldata
->echo_head
;
820 __process_echoes(tty
);
821 mutex_unlock(&ldata
->output_lock
);
825 * add_echo_byte - add a byte to the echo buffer
826 * @c: unicode byte to echo
829 * Add a character or operation byte to the echo buffer.
832 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
834 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
838 * echo_move_back_col - add operation to move back a column
841 * Add an operation to the echo buffer to move back one column.
844 static void echo_move_back_col(struct n_tty_data
*ldata
)
846 add_echo_byte(ECHO_OP_START
, ldata
);
847 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
851 * echo_set_canon_col - add operation to set the canon column
854 * Add an operation to the echo buffer to set the canon column
855 * to the current column.
858 static void echo_set_canon_col(struct n_tty_data
*ldata
)
860 add_echo_byte(ECHO_OP_START
, ldata
);
861 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
865 * echo_erase_tab - add operation to erase a tab
866 * @num_chars: number of character columns already used
867 * @after_tab: true if num_chars starts after a previous tab
870 * Add an operation to the echo buffer to erase a tab.
872 * Called by the eraser function, which knows how many character
873 * columns have been used since either a previous tab or the start
874 * of input. This information will be used later, along with
875 * canon column (if applicable), to go back the correct number
879 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
880 struct n_tty_data
*ldata
)
882 add_echo_byte(ECHO_OP_START
, ldata
);
883 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
885 /* We only need to know this modulo 8 (tab spacing) */
888 /* Set the high bit as a flag if num_chars is after a previous tab */
892 add_echo_byte(num_chars
, ldata
);
896 * echo_char_raw - echo a character raw
897 * @c: unicode byte to echo
898 * @tty: terminal device
900 * Echo user input back onto the screen. This must be called only when
901 * L_ECHO(tty) is true. Called from the driver receive_buf path.
903 * This variant does not treat control characters specially.
906 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
908 if (c
== ECHO_OP_START
) {
909 add_echo_byte(ECHO_OP_START
, ldata
);
910 add_echo_byte(ECHO_OP_START
, ldata
);
912 add_echo_byte(c
, ldata
);
917 * echo_char - echo a character
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 tags control characters to be echoed as "^X"
925 * (where X is the letter representing the control char).
928 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
930 struct n_tty_data
*ldata
= tty
->disc_data
;
932 if (c
== ECHO_OP_START
) {
933 add_echo_byte(ECHO_OP_START
, ldata
);
934 add_echo_byte(ECHO_OP_START
, ldata
);
936 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
937 add_echo_byte(ECHO_OP_START
, ldata
);
938 add_echo_byte(c
, ldata
);
943 * finish_erasing - complete erase
947 static inline void finish_erasing(struct n_tty_data
*ldata
)
949 if (ldata
->erasing
) {
950 echo_char_raw('/', ldata
);
956 * eraser - handle erase function
957 * @c: character input
958 * @tty: terminal device
960 * Perform erase and necessary output when an erase character is
961 * present in the stream from the driver layer. Handles the complexities
962 * of UTF-8 multibyte symbols.
964 * n_tty_receive_buf()/producer path:
965 * caller holds non-exclusive termios_rwsem
968 static void eraser(unsigned char c
, struct tty_struct
*tty
)
970 struct n_tty_data
*ldata
= tty
->disc_data
;
971 enum { ERASE
, WERASE
, KILL
} kill_type
;
976 if (ldata
->read_head
== ldata
->canon_head
) {
977 /* process_output('\a', tty); */ /* what do you think? */
980 if (c
== ERASE_CHAR(tty
))
982 else if (c
== WERASE_CHAR(tty
))
986 ldata
->read_head
= ldata
->canon_head
;
989 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
990 ldata
->read_head
= ldata
->canon_head
;
991 finish_erasing(ldata
);
992 echo_char(KILL_CHAR(tty
), tty
);
993 /* Add a newline if ECHOK is on and ECHOKE is off. */
995 echo_char_raw('\n', ldata
);
1002 while (ldata
->read_head
!= ldata
->canon_head
) {
1003 head
= ldata
->read_head
;
1005 /* erase a single possibly multibyte character */
1008 c
= read_buf(ldata
, head
);
1009 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1011 /* do not partially erase */
1012 if (is_continuation(c
, tty
))
1015 if (kill_type
== WERASE
) {
1016 /* Equivalent to BSD's ALTWERASE. */
1017 if (isalnum(c
) || c
== '_')
1019 else if (seen_alnums
)
1022 cnt
= ldata
->read_head
- head
;
1023 ldata
->read_head
= head
;
1025 if (L_ECHOPRT(tty
)) {
1026 if (!ldata
->erasing
) {
1027 echo_char_raw('\\', ldata
);
1030 /* if cnt > 1, output a multi-byte character */
1034 echo_char_raw(read_buf(ldata
, head
), ldata
);
1035 echo_move_back_col(ldata
);
1037 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1038 echo_char(ERASE_CHAR(tty
), tty
);
1039 } else if (c
== '\t') {
1040 unsigned int num_chars
= 0;
1042 size_t tail
= ldata
->read_head
;
1045 * Count the columns used for characters
1046 * since the start of input or after a
1048 * This info is used to go back the correct
1049 * number of columns.
1051 while (tail
!= ldata
->canon_head
) {
1053 c
= read_buf(ldata
, tail
);
1057 } else if (iscntrl(c
)) {
1060 } else if (!is_continuation(c
, tty
)) {
1064 echo_erase_tab(num_chars
, after_tab
, ldata
);
1066 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1067 echo_char_raw('\b', ldata
);
1068 echo_char_raw(' ', ldata
);
1069 echo_char_raw('\b', ldata
);
1071 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1072 echo_char_raw('\b', ldata
);
1073 echo_char_raw(' ', ldata
);
1074 echo_char_raw('\b', ldata
);
1078 if (kill_type
== ERASE
)
1081 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1082 finish_erasing(ldata
);
1086 * isig - handle the ISIG optio
1090 * Called when a signal is being sent due to terminal input.
1091 * Called from the driver receive_buf path so serialized.
1093 * Performs input and output flush if !NOFLSH. In this context, the echo
1094 * buffer is 'output'. The signal is processed first to alert any current
1095 * readers or writers to discontinue and exit their i/o loops.
1097 * Locking: ctrl_lock
1100 static void isig(int sig
, struct tty_struct
*tty
)
1102 struct n_tty_data
*ldata
= tty
->disc_data
;
1103 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1105 kill_pgrp(tty_pgrp
, sig
, 1);
1109 if (!L_NOFLSH(tty
)) {
1110 up_read(&tty
->termios_rwsem
);
1111 down_write(&tty
->termios_rwsem
);
1113 /* clear echo buffer */
1114 mutex_lock(&ldata
->output_lock
);
1115 ldata
->echo_head
= ldata
->echo_tail
= 0;
1116 ldata
->echo_mark
= ldata
->echo_commit
= 0;
1117 mutex_unlock(&ldata
->output_lock
);
1119 /* clear output buffer */
1120 tty_driver_flush_buffer(tty
);
1122 /* clear input buffer */
1123 reset_buffer_flags(tty
->disc_data
);
1125 /* notify pty master of flush */
1127 n_tty_packet_mode_flush(tty
);
1129 up_write(&tty
->termios_rwsem
);
1130 down_read(&tty
->termios_rwsem
);
1135 * n_tty_receive_break - handle break
1138 * An RS232 break event has been hit in the incoming bitstream. This
1139 * can cause a variety of events depending upon the termios settings.
1141 * n_tty_receive_buf()/producer path:
1142 * caller holds non-exclusive termios_rwsem
1144 * Note: may get exclusive termios_rwsem if flushing input buffer
1147 static void n_tty_receive_break(struct tty_struct
*tty
)
1149 struct n_tty_data
*ldata
= tty
->disc_data
;
1153 if (I_BRKINT(tty
)) {
1157 if (I_PARMRK(tty
)) {
1158 put_tty_queue('\377', ldata
);
1159 put_tty_queue('\0', ldata
);
1161 put_tty_queue('\0', ldata
);
1162 if (waitqueue_active(&tty
->read_wait
))
1163 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1167 * n_tty_receive_overrun - handle overrun reporting
1170 * Data arrived faster than we could process it. While the tty
1171 * driver has flagged this the bits that were missed are gone
1174 * Called from the receive_buf path so single threaded. Does not
1175 * need locking as num_overrun and overrun_time are function
1179 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1181 struct n_tty_data
*ldata
= tty
->disc_data
;
1184 ldata
->num_overrun
++;
1185 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1186 time_after(ldata
->overrun_time
, jiffies
)) {
1187 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1189 ldata
->num_overrun
);
1190 ldata
->overrun_time
= jiffies
;
1191 ldata
->num_overrun
= 0;
1196 * n_tty_receive_parity_error - error notifier
1197 * @tty: terminal device
1200 * Process a parity error and queue the right data to indicate
1201 * the error case if necessary.
1203 * n_tty_receive_buf()/producer path:
1204 * caller holds non-exclusive termios_rwsem
1206 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1208 struct n_tty_data
*ldata
= tty
->disc_data
;
1213 if (I_PARMRK(tty
)) {
1214 put_tty_queue('\377', ldata
);
1215 put_tty_queue('\0', ldata
);
1216 put_tty_queue(c
, ldata
);
1218 put_tty_queue('\0', ldata
);
1220 put_tty_queue(c
, ldata
);
1221 if (waitqueue_active(&tty
->read_wait
))
1222 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1226 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1235 process_echoes(tty
);
1240 * n_tty_receive_char - perform processing
1241 * @tty: terminal device
1244 * Process an individual character of input received from the driver.
1245 * This is serialized with respect to itself by the rules for the
1248 * n_tty_receive_buf()/producer path:
1249 * caller holds non-exclusive termios_rwsem
1250 * publishes canon_head if canonical mode is active
1252 * Returns 1 if LNEXT was received, else returns 0
1256 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1258 struct n_tty_data
*ldata
= tty
->disc_data
;
1261 if (c
== START_CHAR(tty
)) {
1263 process_echoes(tty
);
1266 if (c
== STOP_CHAR(tty
)) {
1273 if (c
== INTR_CHAR(tty
)) {
1274 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1276 } else if (c
== QUIT_CHAR(tty
)) {
1277 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1279 } else if (c
== SUSP_CHAR(tty
)) {
1280 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1285 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1287 process_echoes(tty
);
1295 } else if (c
== '\n' && I_INLCR(tty
))
1298 if (ldata
->icanon
) {
1299 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1300 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1305 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1308 finish_erasing(ldata
);
1309 if (L_ECHOCTL(tty
)) {
1310 echo_char_raw('^', ldata
);
1311 echo_char_raw('\b', ldata
);
1317 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1318 size_t tail
= ldata
->canon_head
;
1320 finish_erasing(ldata
);
1322 echo_char_raw('\n', ldata
);
1323 while (tail
!= ldata
->read_head
) {
1324 echo_char(read_buf(ldata
, tail
), tty
);
1331 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1332 echo_char_raw('\n', ldata
);
1335 goto handle_newline
;
1337 if (c
== EOF_CHAR(tty
)) {
1338 c
= __DISABLED_CHAR
;
1339 goto handle_newline
;
1341 if ((c
== EOL_CHAR(tty
)) ||
1342 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1344 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1347 /* Record the column of first canon char. */
1348 if (ldata
->canon_head
== ldata
->read_head
)
1349 echo_set_canon_col(ldata
);
1354 * XXX does PARMRK doubling happen for
1355 * EOL_CHAR and EOL2_CHAR?
1357 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1358 put_tty_queue(c
, ldata
);
1361 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1362 put_tty_queue(c
, ldata
);
1363 smp_store_release(&ldata
->canon_head
, ldata
->read_head
);
1364 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1365 if (waitqueue_active(&tty
->read_wait
))
1366 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1372 finish_erasing(ldata
);
1374 echo_char_raw('\n', ldata
);
1376 /* Record the column of first canon char. */
1377 if (ldata
->canon_head
== ldata
->read_head
)
1378 echo_set_canon_col(ldata
);
1384 /* PARMRK doubling check */
1385 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1386 put_tty_queue(c
, ldata
);
1388 put_tty_queue(c
, ldata
);
1393 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1395 struct n_tty_data
*ldata
= tty
->disc_data
;
1397 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1399 process_echoes(tty
);
1402 finish_erasing(ldata
);
1403 /* Record the column of first canon char. */
1404 if (ldata
->canon_head
== ldata
->read_head
)
1405 echo_set_canon_col(ldata
);
1409 /* PARMRK doubling check */
1410 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1411 put_tty_queue(c
, ldata
);
1412 put_tty_queue(c
, ldata
);
1415 static void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1417 n_tty_receive_char_inline(tty
, c
);
1421 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1423 struct n_tty_data
*ldata
= tty
->disc_data
;
1425 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1427 process_echoes(tty
);
1430 finish_erasing(ldata
);
1431 /* Record the column of first canon char. */
1432 if (ldata
->canon_head
== ldata
->read_head
)
1433 echo_set_canon_col(ldata
);
1437 put_tty_queue(c
, ldata
);
1440 static void n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1444 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1448 if (c
== STOP_CHAR(tty
))
1450 else if (c
== START_CHAR(tty
) ||
1451 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1452 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1453 c
!= SUSP_CHAR(tty
))) {
1455 process_echoes(tty
);
1461 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1467 n_tty_receive_break(tty
);
1471 n_tty_receive_parity_error(tty
, c
);
1474 n_tty_receive_overrun(tty
);
1477 printk(KERN_ERR
"%s: unknown flag %d\n",
1478 tty_name(tty
, buf
), flag
);
1484 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1486 struct n_tty_data
*ldata
= tty
->disc_data
;
1489 if (likely(flag
== TTY_NORMAL
)) {
1492 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1494 n_tty_receive_char(tty
, c
);
1496 n_tty_receive_char_flagged(tty
, c
, flag
);
1500 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1501 char *fp
, int count
)
1503 struct n_tty_data
*ldata
= tty
->disc_data
;
1506 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1507 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1508 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1509 ldata
->read_head
+= n
;
1513 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1514 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1515 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1516 ldata
->read_head
+= n
;
1520 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1521 char *fp
, int count
)
1523 struct n_tty_data
*ldata
= tty
->disc_data
;
1524 char flag
= TTY_NORMAL
;
1529 if (likely(flag
== TTY_NORMAL
))
1530 put_tty_queue(*cp
++, ldata
);
1532 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1537 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1538 char *fp
, int count
)
1540 char flag
= TTY_NORMAL
;
1545 if (likely(flag
== TTY_NORMAL
))
1546 n_tty_receive_char_closing(tty
, *cp
++);
1548 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1553 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1554 char *fp
, int count
)
1556 struct n_tty_data
*ldata
= tty
->disc_data
;
1557 char flag
= TTY_NORMAL
;
1562 if (likely(flag
== TTY_NORMAL
)) {
1563 unsigned char c
= *cp
++;
1567 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1569 if (L_EXTPROC(tty
)) {
1570 put_tty_queue(c
, ldata
);
1573 if (!test_bit(c
, ldata
->char_map
))
1574 n_tty_receive_char_inline(tty
, c
);
1575 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1578 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1582 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1587 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1588 char *fp
, int count
)
1590 struct n_tty_data
*ldata
= tty
->disc_data
;
1591 char flag
= TTY_NORMAL
;
1596 if (likely(flag
== TTY_NORMAL
)) {
1597 unsigned char c
= *cp
++;
1599 if (!test_bit(c
, ldata
->char_map
))
1600 n_tty_receive_char_fast(tty
, c
);
1601 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1604 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1608 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1612 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1613 char *fp
, int count
)
1615 struct n_tty_data
*ldata
= tty
->disc_data
;
1616 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1618 if (ldata
->real_raw
)
1619 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1620 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1621 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1622 else if (tty
->closing
&& !L_EXTPROC(tty
))
1623 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1626 char flag
= TTY_NORMAL
;
1630 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1634 if (!preops
&& !I_PARMRK(tty
))
1635 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1637 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1640 if (tty
->ops
->flush_chars
)
1641 tty
->ops
->flush_chars(tty
);
1644 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1647 /* publish read_head to consumer */
1648 smp_store_release(&ldata
->commit_head
, ldata
->read_head
);
1650 if ((read_cnt(ldata
) >= ldata
->minimum_to_wake
) || L_EXTPROC(tty
)) {
1651 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1652 if (waitqueue_active(&tty
->read_wait
))
1653 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1658 * n_tty_receive_buf_common - process input
1659 * @tty: device to receive input
1661 * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
1662 * @count: number of input chars in @cp
1664 * Called by the terminal driver when a block of characters has
1665 * been received. This function must be called from soft contexts
1666 * not from interrupt context. The driver is responsible for making
1667 * calls one at a time and in order (or using flush_to_ldisc)
1669 * Returns the # of input chars from @cp which were processed.
1671 * In canonical mode, the maximum line length is 4096 chars (including
1672 * the line termination char); lines longer than 4096 chars are
1673 * truncated. After 4095 chars, input data is still processed but
1674 * not stored. Overflow processing ensures the tty can always
1675 * receive more input until at least one line can be read.
1677 * In non-canonical mode, the read buffer will only accept 4095 chars;
1678 * this provides the necessary space for a newline char if the input
1679 * mode is switched to canonical.
1681 * Note it is possible for the read buffer to _contain_ 4096 chars
1682 * in non-canonical mode: the read buffer could already contain the
1683 * maximum canon line of 4096 chars when the mode is switched to
1686 * n_tty_receive_buf()/producer path:
1687 * claims non-exclusive termios_rwsem
1688 * publishes commit_head or canon_head
1691 n_tty_receive_buf_common(struct tty_struct
*tty
, const unsigned char *cp
,
1692 char *fp
, int count
, int flow
)
1694 struct n_tty_data
*ldata
= tty
->disc_data
;
1695 int room
, n
, rcvd
= 0, overflow
;
1697 down_read(&tty
->termios_rwsem
);
1701 * When PARMRK is set, each input char may take up to 3 chars
1702 * in the read buf; reduce the buffer space avail by 3x
1704 * If we are doing input canonicalization, and there are no
1705 * pending newlines, let characters through without limit, so
1706 * that erase characters will be handled. Other excess
1707 * characters will be beeped.
1709 * paired with store in *_copy_from_read_buf() -- guarantees
1710 * the consumer has loaded the data in read_buf up to the new
1711 * read_tail (so this producer will not overwrite unread data)
1713 size_t tail
= smp_load_acquire(&ldata
->read_tail
);
1715 room
= N_TTY_BUF_SIZE
- (ldata
->read_head
- tail
);
1717 room
= (room
+ 2) / 3;
1720 overflow
= ldata
->icanon
&& ldata
->canon_head
== tail
;
1721 if (overflow
&& room
< 0)
1724 ldata
->no_room
= flow
&& !room
;
1728 n
= min(count
, room
);
1732 /* ignore parity errors if handling overflow */
1733 if (!overflow
|| !fp
|| *fp
!= TTY_PARITY
)
1734 __receive_buf(tty
, cp
, fp
, n
);
1743 tty
->receive_room
= room
;
1745 /* Unthrottle if handling overflow on pty */
1746 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
) {
1748 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
1749 tty_unthrottle_safe(tty
);
1750 __tty_set_flow_change(tty
, 0);
1753 n_tty_check_throttle(tty
);
1755 up_read(&tty
->termios_rwsem
);
1760 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1761 char *fp
, int count
)
1763 n_tty_receive_buf_common(tty
, cp
, fp
, count
, 0);
1766 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1767 char *fp
, int count
)
1769 return n_tty_receive_buf_common(tty
, cp
, fp
, count
, 1);
1772 int is_ignored(int sig
)
1774 return (sigismember(¤t
->blocked
, sig
) ||
1775 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1779 * n_tty_set_termios - termios data changed
1781 * @old: previous data
1783 * Called by the tty layer when the user changes termios flags so
1784 * that the line discipline can plan ahead. This function cannot sleep
1785 * and is protected from re-entry by the tty layer. The user is
1786 * guaranteed that this function will not be re-entered or in progress
1787 * when the ldisc is closed.
1789 * Locking: Caller holds tty->termios_rwsem
1792 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1794 struct n_tty_data
*ldata
= tty
->disc_data
;
1796 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1797 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1798 ldata
->line_start
= ldata
->read_tail
;
1799 if (!L_ICANON(tty
) || !read_cnt(ldata
)) {
1800 ldata
->canon_head
= ldata
->read_tail
;
1803 set_bit((ldata
->read_head
- 1) & (N_TTY_BUF_SIZE
- 1),
1805 ldata
->canon_head
= ldata
->read_head
;
1808 ldata
->commit_head
= ldata
->read_head
;
1813 ldata
->icanon
= (L_ICANON(tty
) != 0);
1815 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1816 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1817 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1819 bitmap_zero(ldata
->char_map
, 256);
1821 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1822 set_bit('\r', ldata
->char_map
);
1824 set_bit('\n', ldata
->char_map
);
1826 if (L_ICANON(tty
)) {
1827 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1828 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1829 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1830 set_bit('\n', ldata
->char_map
);
1831 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1832 if (L_IEXTEN(tty
)) {
1833 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1834 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1835 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1837 set_bit(REPRINT_CHAR(tty
),
1842 set_bit(START_CHAR(tty
), ldata
->char_map
);
1843 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1846 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1847 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1848 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1850 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1852 ldata
->real_raw
= 0;
1855 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1856 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1857 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1858 ldata
->real_raw
= 1;
1860 ldata
->real_raw
= 0;
1863 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1864 * been stopped by STOP_CHAR(tty) before it.
1866 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1868 process_echoes(tty
);
1871 /* The termios change make the tty ready for I/O */
1872 if (waitqueue_active(&tty
->write_wait
))
1873 wake_up_interruptible(&tty
->write_wait
);
1874 if (waitqueue_active(&tty
->read_wait
))
1875 wake_up_interruptible(&tty
->read_wait
);
1879 * n_tty_close - close the ldisc for this tty
1882 * Called from the terminal layer when this line discipline is
1883 * being shut down, either because of a close or becsuse of a
1884 * discipline change. The function will not be called while other
1885 * ldisc methods are in progress.
1888 static void n_tty_close(struct tty_struct
*tty
)
1890 struct n_tty_data
*ldata
= tty
->disc_data
;
1893 n_tty_packet_mode_flush(tty
);
1896 tty
->disc_data
= NULL
;
1900 * n_tty_open - open an ldisc
1901 * @tty: terminal to open
1903 * Called when this line discipline is being attached to the
1904 * terminal device. Can sleep. Called serialized so that no
1905 * other events will occur in parallel. No further open will occur
1909 static int n_tty_open(struct tty_struct
*tty
)
1911 struct n_tty_data
*ldata
;
1913 /* Currently a malloc failure here can panic */
1914 ldata
= vmalloc(sizeof(*ldata
));
1918 ldata
->overrun_time
= jiffies
;
1919 mutex_init(&ldata
->atomic_read_lock
);
1920 mutex_init(&ldata
->output_lock
);
1922 tty
->disc_data
= ldata
;
1923 reset_buffer_flags(tty
->disc_data
);
1925 ldata
->canon_column
= 0;
1926 ldata
->minimum_to_wake
= 1;
1927 ldata
->num_overrun
= 0;
1931 /* indicate buffer work may resume */
1932 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1933 n_tty_set_termios(tty
, NULL
);
1934 tty_unthrottle(tty
);
1941 static inline int input_available_p(struct tty_struct
*tty
, int poll
)
1943 struct n_tty_data
*ldata
= tty
->disc_data
;
1944 int amt
= poll
&& !TIME_CHAR(tty
) && MIN_CHAR(tty
) ? MIN_CHAR(tty
) : 1;
1946 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1947 return ldata
->canon_head
!= ldata
->read_tail
;
1949 return ldata
->commit_head
- ldata
->read_tail
>= amt
;
1953 * copy_from_read_buf - copy read data directly
1954 * @tty: terminal device
1958 * Helper function to speed up n_tty_read. It is only called when
1959 * ICANON is off; it copies characters straight from the tty queue to
1960 * user space directly. It can be profitably called twice; once to
1961 * drain the space from the tail pointer to the (physical) end of the
1962 * buffer, and once to drain the space from the (physical) beginning of
1963 * the buffer to head pointer.
1965 * Called under the ldata->atomic_read_lock sem
1967 * n_tty_read()/consumer path:
1968 * caller holds non-exclusive termios_rwsem
1969 * read_tail published
1972 static int copy_from_read_buf(struct tty_struct
*tty
,
1973 unsigned char __user
**b
,
1977 struct n_tty_data
*ldata
= tty
->disc_data
;
1981 size_t head
= smp_load_acquire(&ldata
->commit_head
);
1982 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1985 n
= min(head
- ldata
->read_tail
, N_TTY_BUF_SIZE
- tail
);
1988 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1990 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
1991 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
1993 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ n
);
1994 /* Turn single EOF into zero-length read */
1995 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&&
1996 (head
== ldata
->read_tail
))
2005 * canon_copy_from_read_buf - copy read data in canonical mode
2006 * @tty: terminal device
2010 * Helper function for n_tty_read. It is only called when ICANON is on;
2011 * it copies one line of input up to and including the line-delimiting
2012 * character into the user-space buffer.
2014 * NB: When termios is changed from non-canonical to canonical mode and
2015 * the read buffer contains data, n_tty_set_termios() simulates an EOF
2016 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
2017 * This causes data already processed as input to be immediately available
2018 * as input although a newline has not been received.
2020 * Called under the atomic_read_lock mutex
2022 * n_tty_read()/consumer path:
2023 * caller holds non-exclusive termios_rwsem
2024 * read_tail published
2027 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
2028 unsigned char __user
**b
,
2031 struct n_tty_data
*ldata
= tty
->disc_data
;
2032 size_t n
, size
, more
, c
;
2038 /* N.B. avoid overrun if nr == 0 */
2039 n
= min(*nr
, smp_load_acquire(&ldata
->canon_head
) - ldata
->read_tail
);
2043 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2044 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
2046 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2047 __func__
, *nr
, tail
, n
, size
);
2049 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
2050 more
= n
- (size
- tail
);
2051 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2052 /* scan wrapped without finding set bit */
2053 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2056 } else if (eol
!= size
)
2059 size
= N_TTY_BUF_SIZE
- tail
;
2066 if (found
&& !ldata
->push
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
2068 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
2071 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2072 __func__
, eol
, found
, n
, c
, size
, more
);
2075 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), size
);
2078 ret
= copy_to_user(*b
+ size
, ldata
->read_buf
, n
- size
);
2080 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2088 clear_bit(eol
, ldata
->read_flags
);
2089 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ c
);
2093 ldata
->line_start
= ldata
->read_tail
;
2096 tty_audit_push(tty
);
2098 return eof_push
? -EAGAIN
: 0;
2101 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2105 * job_control - check job control
2107 * @file: file handle
2109 * Perform job control management checks on this file/tty descriptor
2110 * and if appropriate send any needed signals and return a negative
2111 * error code if action should be taken.
2113 * Locking: redirected write test is safe
2114 * current->signal->tty check is safe
2115 * ctrl_lock to safely reference tty->pgrp
2118 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2120 /* Job control check -- must be done at start and after
2121 every sleep (POSIX.1 7.1.1.4). */
2122 /* NOTE: not yet done after every sleep pending a thorough
2123 check of the logic of this change. -- jlc */
2124 /* don't stop on /dev/console */
2125 if (file
->f_op
->write
== redirected_tty_write
||
2126 current
->signal
->tty
!= tty
)
2129 spin_lock_irq(&tty
->ctrl_lock
);
2131 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2132 else if (task_pgrp(current
) != tty
->pgrp
) {
2133 spin_unlock_irq(&tty
->ctrl_lock
);
2134 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
2136 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
2137 set_thread_flag(TIF_SIGPENDING
);
2138 return -ERESTARTSYS
;
2140 spin_unlock_irq(&tty
->ctrl_lock
);
2146 * n_tty_read - read function for tty
2148 * @file: file object
2149 * @buf: userspace buffer pointer
2152 * Perform reads for the line discipline. We are guaranteed that the
2153 * line discipline will not be closed under us but we may get multiple
2154 * parallel readers and must handle this ourselves. We may also get
2155 * a hangup. Always called in user context, may sleep.
2157 * This code must be sure never to sleep through a hangup.
2159 * n_tty_read()/consumer path:
2160 * claims non-exclusive termios_rwsem
2161 * publishes read_tail
2164 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2165 unsigned char __user
*buf
, size_t nr
)
2167 struct n_tty_data
*ldata
= tty
->disc_data
;
2168 unsigned char __user
*b
= buf
;
2169 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2177 c
= job_control(tty
, file
);
2182 * Internal serialization of reads.
2184 if (file
->f_flags
& O_NONBLOCK
) {
2185 if (!mutex_trylock(&ldata
->atomic_read_lock
))
2188 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
))
2189 return -ERESTARTSYS
;
2192 down_read(&tty
->termios_rwsem
);
2195 timeout
= MAX_SCHEDULE_TIMEOUT
;
2196 if (!ldata
->icanon
) {
2197 minimum
= MIN_CHAR(tty
);
2199 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2201 ldata
->minimum_to_wake
= 1;
2202 else if (!waitqueue_active(&tty
->read_wait
) ||
2203 (ldata
->minimum_to_wake
> minimum
))
2204 ldata
->minimum_to_wake
= minimum
;
2206 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2207 ldata
->minimum_to_wake
= minimum
= 1;
2211 packet
= tty
->packet
;
2212 tail
= ldata
->read_tail
;
2214 add_wait_queue(&tty
->read_wait
, &wait
);
2216 /* First test for status change. */
2217 if (packet
&& tty
->link
->ctrl_status
) {
2221 spin_lock_irq(&tty
->link
->ctrl_lock
);
2222 cs
= tty
->link
->ctrl_status
;
2223 tty
->link
->ctrl_status
= 0;
2224 spin_unlock_irq(&tty
->link
->ctrl_lock
);
2225 if (tty_put_user(tty
, cs
, b
++)) {
2234 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2235 ((minimum
- (b
- buf
)) >= 1))
2236 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2238 if (!input_available_p(tty
, 0)) {
2239 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
2243 if (tty_hung_up_p(file
))
2247 if (file
->f_flags
& O_NONBLOCK
) {
2251 if (signal_pending(current
)) {
2252 retval
= -ERESTARTSYS
;
2255 up_read(&tty
->termios_rwsem
);
2257 timeout
= wait_woken(&wait
, TASK_INTERRUPTIBLE
,
2260 down_read(&tty
->termios_rwsem
);
2264 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2265 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2266 if (retval
== -EAGAIN
) {
2274 /* Deal with packet mode. */
2275 if (packet
&& b
== buf
) {
2276 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2284 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2285 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2292 n_tty_check_unthrottle(tty
);
2294 if (b
- buf
>= minimum
)
2299 if (tail
!= ldata
->read_tail
)
2300 n_tty_kick_worker(tty
);
2301 up_read(&tty
->termios_rwsem
);
2303 remove_wait_queue(&tty
->read_wait
, &wait
);
2304 if (!waitqueue_active(&tty
->read_wait
))
2305 ldata
->minimum_to_wake
= minimum
;
2307 mutex_unlock(&ldata
->atomic_read_lock
);
2316 * n_tty_write - write function for tty
2318 * @file: file object
2319 * @buf: userspace buffer pointer
2322 * Write function of the terminal device. This is serialized with
2323 * respect to other write callers but not to termios changes, reads
2324 * and other such events. Since the receive code will echo characters,
2325 * thus calling driver write methods, the output_lock is used in
2326 * the output processing functions called here as well as in the
2327 * echo processing function to protect the column state and space
2328 * left in the buffer.
2330 * This code must be sure never to sleep through a hangup.
2332 * Locking: output_lock to protect column state and space left
2333 * (note that the process_output*() functions take this
2337 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2338 const unsigned char *buf
, size_t nr
)
2340 const unsigned char *b
= buf
;
2341 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2345 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2346 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2347 retval
= tty_check_change(tty
);
2352 down_read(&tty
->termios_rwsem
);
2354 /* Write out any echoed characters that are still pending */
2355 process_echoes(tty
);
2357 add_wait_queue(&tty
->write_wait
, &wait
);
2359 if (signal_pending(current
)) {
2360 retval
= -ERESTARTSYS
;
2363 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2369 ssize_t num
= process_output_block(tty
, b
, nr
);
2381 if (process_output(c
, tty
) < 0)
2385 if (tty
->ops
->flush_chars
)
2386 tty
->ops
->flush_chars(tty
);
2388 struct n_tty_data
*ldata
= tty
->disc_data
;
2391 mutex_lock(&ldata
->output_lock
);
2392 c
= tty
->ops
->write(tty
, b
, nr
);
2393 mutex_unlock(&ldata
->output_lock
);
2406 if (file
->f_flags
& O_NONBLOCK
) {
2410 up_read(&tty
->termios_rwsem
);
2412 wait_woken(&wait
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2414 down_read(&tty
->termios_rwsem
);
2417 remove_wait_queue(&tty
->write_wait
, &wait
);
2418 if (b
- buf
!= nr
&& tty
->fasync
)
2419 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2420 up_read(&tty
->termios_rwsem
);
2421 return (b
- buf
) ? b
- buf
: retval
;
2425 * n_tty_poll - poll method for N_TTY
2426 * @tty: terminal device
2427 * @file: file accessing it
2430 * Called when the line discipline is asked to poll() for data or
2431 * for special events. This code is not serialized with respect to
2432 * other events save open/close.
2434 * This code must be sure never to sleep through a hangup.
2435 * Called without the kernel lock held - fine
2438 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2441 struct n_tty_data
*ldata
= tty
->disc_data
;
2442 unsigned int mask
= 0;
2444 poll_wait(file
, &tty
->read_wait
, wait
);
2445 poll_wait(file
, &tty
->write_wait
, wait
);
2446 if (input_available_p(tty
, 1))
2447 mask
|= POLLIN
| POLLRDNORM
;
2448 if (tty
->packet
&& tty
->link
->ctrl_status
)
2449 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2450 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2452 if (tty_hung_up_p(file
))
2454 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2455 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2456 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2458 ldata
->minimum_to_wake
= 1;
2460 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2461 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2462 tty_write_room(tty
) > 0)
2463 mask
|= POLLOUT
| POLLWRNORM
;
2467 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2469 size_t nr
, head
, tail
;
2471 if (ldata
->canon_head
== ldata
->read_tail
)
2473 head
= ldata
->canon_head
;
2474 tail
= ldata
->read_tail
;
2476 /* Skip EOF-chars.. */
2477 while (head
!= tail
) {
2478 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2479 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2486 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2487 unsigned int cmd
, unsigned long arg
)
2489 struct n_tty_data
*ldata
= tty
->disc_data
;
2494 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2496 down_write(&tty
->termios_rwsem
);
2498 retval
= inq_canon(ldata
);
2500 retval
= read_cnt(ldata
);
2501 up_write(&tty
->termios_rwsem
);
2502 return put_user(retval
, (unsigned int __user
*) arg
);
2504 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2508 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2510 struct n_tty_data
*ldata
= tty
->disc_data
;
2512 if (!waitqueue_active(&tty
->read_wait
)) {
2514 ldata
->minimum_to_wake
= 1;
2515 else if (!tty
->fasync
)
2516 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2520 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2521 .magic
= TTY_LDISC_MAGIC
,
2524 .close
= n_tty_close
,
2525 .flush_buffer
= n_tty_flush_buffer
,
2526 .chars_in_buffer
= n_tty_chars_in_buffer
,
2528 .write
= n_tty_write
,
2529 .ioctl
= n_tty_ioctl
,
2530 .set_termios
= n_tty_set_termios
,
2532 .receive_buf
= n_tty_receive_buf
,
2533 .write_wakeup
= n_tty_write_wakeup
,
2534 .fasync
= n_tty_fasync
,
2535 .receive_buf2
= n_tty_receive_buf2
,
2539 * n_tty_inherit_ops - inherit N_TTY methods
2540 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2542 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2546 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2548 *ops
= tty_ldisc_N_TTY
;
2550 ops
->refcount
= ops
->flags
= 0;
2552 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);