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>
55 /* number of characters left in xmit buffer before select has we have room */
56 #define WAKEUP_CHARS 256
59 * This defines the low- and high-watermarks for throttling and
60 * unthrottling the TTY driver. These watermarks are used for
61 * controlling the space in the read buffer.
63 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
64 #define TTY_THRESHOLD_UNTHROTTLE 128
67 * Special byte codes used in the echo buffer to represent operations
68 * or special handling of characters. Bytes in the echo buffer that
69 * are not part of such special blocks are treated as normal character
72 #define ECHO_OP_START 0xff
73 #define ECHO_OP_MOVE_BACK_COL 0x80
74 #define ECHO_OP_SET_CANON_COL 0x81
75 #define ECHO_OP_ERASE_TAB 0x82
77 #define ECHO_COMMIT_WATERMARK 256
78 #define ECHO_BLOCK 256
79 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
84 # define n_tty_trace(f, args...) trace_printk(f, ##args)
86 # define n_tty_trace(f, args...)
90 /* producer-published */
95 DECLARE_BITMAP(char_map
, 256);
97 /* private to n_tty_receive_overrun (single-threaded) */
98 unsigned long overrun_time
;
104 /* must hold exclusive termios_rwsem to reset these */
105 unsigned char lnext
:1, erasing
:1, raw
:1, real_raw
:1, icanon
:1;
107 /* shared by producer and consumer */
108 char read_buf
[N_TTY_BUF_SIZE
];
109 DECLARE_BITMAP(read_flags
, N_TTY_BUF_SIZE
);
110 unsigned char echo_buf
[N_TTY_BUF_SIZE
];
114 /* consumer-published */
118 /* protected by output lock */
120 unsigned int canon_column
;
123 struct mutex atomic_read_lock
;
124 struct mutex output_lock
;
127 static inline size_t read_cnt(struct n_tty_data
*ldata
)
129 return ldata
->read_head
- ldata
->read_tail
;
132 static inline unsigned char read_buf(struct n_tty_data
*ldata
, size_t i
)
134 return ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
137 static inline unsigned char *read_buf_addr(struct n_tty_data
*ldata
, size_t i
)
139 return &ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
142 static inline unsigned char echo_buf(struct n_tty_data
*ldata
, size_t i
)
144 return ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
147 static inline unsigned char *echo_buf_addr(struct n_tty_data
*ldata
, size_t i
)
149 return &ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
152 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
153 unsigned char __user
*ptr
)
155 struct n_tty_data
*ldata
= tty
->disc_data
;
157 tty_audit_add_data(tty
, &x
, 1, ldata
->icanon
);
158 return put_user(x
, ptr
);
161 static int receive_room(struct tty_struct
*tty
)
163 struct n_tty_data
*ldata
= tty
->disc_data
;
167 /* Multiply read_cnt by 3, since each byte might take up to
168 * three times as many spaces when PARMRK is set (depending on
169 * its flags, e.g. parity error). */
170 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) * 3 - 1;
172 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) - 1;
175 * If we are doing input canonicalization, and there are no
176 * pending newlines, let characters through without limit, so
177 * that erase characters will be handled. Other excess
178 * characters will be beeped.
181 left
= ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
;
187 * n_tty_set_room - receive space
190 * Re-schedules the flip buffer work if space just became available.
192 * Caller holds exclusive termios_rwsem
194 * n_tty_read()/consumer path:
195 * holds non-exclusive termios_rwsem
198 static void n_tty_set_room(struct tty_struct
*tty
)
200 struct n_tty_data
*ldata
= tty
->disc_data
;
202 /* Did this open up the receive buffer? We may need to flip */
203 if (unlikely(ldata
->no_room
) && receive_room(tty
)) {
206 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
207 "scheduling with invalid itty\n");
208 /* see if ldisc has been killed - if so, this means that
209 * even though the ldisc has been halted and ->buf.work
210 * cancelled, ->buf.work is about to be rescheduled
212 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
213 "scheduling buffer work for halted ldisc\n");
214 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
218 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
220 struct n_tty_data
*ldata
= tty
->disc_data
;
226 n
= ldata
->canon_head
- ldata
->read_tail
;
231 * n_tty_write_wakeup - asynchronous I/O notifier
234 * Required for the ptys, serial driver etc. since processes
235 * that attach themselves to the master and rely on ASYNC
236 * IO must be woken up
239 static void n_tty_write_wakeup(struct tty_struct
*tty
)
241 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
242 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
245 static void n_tty_check_throttle(struct tty_struct
*tty
)
247 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
)
250 * Check the remaining room for the input canonicalization
251 * mode. We don't want to throttle the driver if we're in
252 * canonical mode and don't have a newline yet!
256 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
257 if (receive_room(tty
) >= TTY_THRESHOLD_THROTTLE
)
259 throttled
= tty_throttle_safe(tty
);
263 __tty_set_flow_change(tty
, 0);
266 static inline void n_tty_check_unthrottle(struct tty_struct
*tty
)
268 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
269 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
270 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
275 n_tty_write_wakeup(tty
->link
);
276 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
280 /* If there is enough space in the read buffer now, let the
281 * low-level driver know. We use chars_in_buffer() to
282 * check the buffer, as it now knows about canonical mode.
283 * Otherwise, if the driver is throttled and the line is
284 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
285 * we won't get any more characters.
290 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
291 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
296 unthrottled
= tty_unthrottle_safe(tty
);
300 __tty_set_flow_change(tty
, 0);
304 * put_tty_queue - add character to tty
308 * Add a character to the tty read_buf queue.
310 * n_tty_receive_buf()/producer path:
311 * caller holds non-exclusive termios_rwsem
314 * read_head is only considered 'published' if canonical mode is
318 static void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
320 if (read_cnt(ldata
) < N_TTY_BUF_SIZE
) {
321 *read_buf_addr(ldata
, ldata
->read_head
) = c
;
327 * reset_buffer_flags - reset buffer state
328 * @tty: terminal to reset
330 * Reset the read buffer counters and clear the flags.
331 * Called from n_tty_open() and n_tty_flush_buffer().
333 * Locking: caller holds exclusive termios_rwsem
334 * (or locking is not required)
337 static void reset_buffer_flags(struct n_tty_data
*ldata
)
339 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
340 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
341 ldata
->line_start
= 0;
344 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
347 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
351 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
352 if (tty
->link
->packet
) {
353 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
354 wake_up_interruptible(&tty
->link
->read_wait
);
356 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
360 * n_tty_flush_buffer - clean input queue
361 * @tty: terminal device
363 * Flush the input buffer. Called when the tty layer wants the
364 * buffer flushed (eg at hangup) or when the N_TTY line discipline
365 * internally has to clean the pending queue (for example some signals).
367 * Holds termios_rwsem to exclude producer/consumer while
368 * buffer indices are reset.
370 * Locking: ctrl_lock, exclusive termios_rwsem
373 static void n_tty_flush_buffer(struct tty_struct
*tty
)
375 down_write(&tty
->termios_rwsem
);
376 reset_buffer_flags(tty
->disc_data
);
380 n_tty_packet_mode_flush(tty
);
381 up_write(&tty
->termios_rwsem
);
385 * n_tty_chars_in_buffer - report available bytes
388 * Report the number of characters buffered to be delivered to user
389 * at this instant in time.
391 * Locking: exclusive termios_rwsem
394 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
398 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
400 down_write(&tty
->termios_rwsem
);
401 n
= chars_in_buffer(tty
);
402 up_write(&tty
->termios_rwsem
);
407 * is_utf8_continuation - utf8 multibyte check
410 * Returns true if the utf8 character 'c' is a multibyte continuation
411 * character. We use this to correctly compute the on screen size
412 * of the character when printing
415 static inline int is_utf8_continuation(unsigned char c
)
417 return (c
& 0xc0) == 0x80;
421 * is_continuation - multibyte check
424 * Returns true if the utf8 character 'c' is a multibyte continuation
425 * character and the terminal is in unicode mode.
428 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
430 return I_IUTF8(tty
) && is_utf8_continuation(c
);
434 * do_output_char - output one character
435 * @c: character (or partial unicode symbol)
436 * @tty: terminal device
437 * @space: space available in tty driver write buffer
439 * This is a helper function that handles one output character
440 * (including special characters like TAB, CR, LF, etc.),
441 * doing OPOST processing and putting the results in the
442 * tty driver's write buffer.
444 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
445 * and NLDLY. They simply aren't relevant in the world today.
446 * If you ever need them, add them here.
448 * Returns the number of bytes of buffer space used or -1 if
451 * Locking: should be called under the output_lock to protect
452 * the column state and space left in the buffer
455 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
457 struct n_tty_data
*ldata
= tty
->disc_data
;
470 ldata
->canon_column
= ldata
->column
= 0;
471 tty
->ops
->write(tty
, "\r\n", 2);
474 ldata
->canon_column
= ldata
->column
;
477 if (O_ONOCR(tty
) && ldata
->column
== 0)
482 ldata
->canon_column
= ldata
->column
= 0;
485 ldata
->canon_column
= ldata
->column
= 0;
488 spaces
= 8 - (ldata
->column
& 7);
489 if (O_TABDLY(tty
) == XTABS
) {
492 ldata
->column
+= spaces
;
493 tty
->ops
->write(tty
, " ", spaces
);
496 ldata
->column
+= spaces
;
499 if (ldata
->column
> 0)
506 if (!is_continuation(c
, tty
))
512 tty_put_char(tty
, c
);
517 * process_output - output post processor
518 * @c: character (or partial unicode symbol)
519 * @tty: terminal device
521 * Output one character with OPOST processing.
522 * Returns -1 when the output device is full and the character
525 * Locking: output_lock to protect column state and space left
526 * (also, this is called from n_tty_write under the
527 * tty layer write lock)
530 static int process_output(unsigned char c
, struct tty_struct
*tty
)
532 struct n_tty_data
*ldata
= tty
->disc_data
;
535 mutex_lock(&ldata
->output_lock
);
537 space
= tty_write_room(tty
);
538 retval
= do_output_char(c
, tty
, space
);
540 mutex_unlock(&ldata
->output_lock
);
548 * process_output_block - block post processor
549 * @tty: terminal device
550 * @buf: character buffer
551 * @nr: number of bytes to output
553 * Output a block of characters with OPOST processing.
554 * Returns the number of characters output.
556 * This path is used to speed up block console writes, among other
557 * things when processing blocks of output data. It handles only
558 * the simple cases normally found and helps to generate blocks of
559 * symbols for the console driver and thus improve performance.
561 * Locking: output_lock to protect column state and space left
562 * (also, this is called from n_tty_write under the
563 * tty layer write lock)
566 static ssize_t
process_output_block(struct tty_struct
*tty
,
567 const unsigned char *buf
, unsigned int nr
)
569 struct n_tty_data
*ldata
= tty
->disc_data
;
572 const unsigned char *cp
;
574 mutex_lock(&ldata
->output_lock
);
576 space
= tty_write_room(tty
);
578 mutex_unlock(&ldata
->output_lock
);
584 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
585 unsigned char c
= *cp
;
593 ldata
->canon_column
= ldata
->column
;
596 if (O_ONOCR(tty
) && ldata
->column
== 0)
600 ldata
->canon_column
= ldata
->column
= 0;
605 if (ldata
->column
> 0)
612 if (!is_continuation(c
, tty
))
619 i
= tty
->ops
->write(tty
, buf
, i
);
621 mutex_unlock(&ldata
->output_lock
);
626 * process_echoes - write pending echo characters
627 * @tty: terminal device
629 * Write previously buffered echo (and other ldisc-generated)
630 * characters to the tty.
632 * Characters generated by the ldisc (including echoes) need to
633 * be buffered because the driver's write buffer can fill during
634 * heavy program output. Echoing straight to the driver will
635 * often fail under these conditions, causing lost characters and
636 * resulting mismatches of ldisc state information.
638 * Since the ldisc state must represent the characters actually sent
639 * to the driver at the time of the write, operations like certain
640 * changes in column state are also saved in the buffer and executed
643 * A circular fifo buffer is used so that the most recent characters
644 * are prioritized. Also, when control characters are echoed with a
645 * prefixed "^", the pair is treated atomically and thus not separated.
647 * Locking: callers must hold output_lock
650 static size_t __process_echoes(struct tty_struct
*tty
)
652 struct n_tty_data
*ldata
= tty
->disc_data
;
653 int space
, old_space
;
657 old_space
= space
= tty_write_room(tty
);
659 tail
= ldata
->echo_tail
;
660 while (ldata
->echo_commit
!= tail
) {
661 c
= echo_buf(ldata
, tail
);
662 if (c
== ECHO_OP_START
) {
664 int no_space_left
= 0;
667 * If the buffer byte is the start of a multi-byte
668 * operation, get the next byte, which is either the
669 * op code or a control character value.
671 op
= echo_buf(ldata
, tail
+ 1);
674 unsigned int num_chars
, num_bs
;
676 case ECHO_OP_ERASE_TAB
:
677 num_chars
= echo_buf(ldata
, tail
+ 2);
680 * Determine how many columns to go back
681 * in order to erase the tab.
682 * This depends on the number of columns
683 * used by other characters within the tab
684 * area. If this (modulo 8) count is from
685 * the start of input rather than from a
686 * previous tab, we offset by canon column.
687 * Otherwise, tab spacing is normal.
689 if (!(num_chars
& 0x80))
690 num_chars
+= ldata
->canon_column
;
691 num_bs
= 8 - (num_chars
& 7);
693 if (num_bs
> space
) {
699 tty_put_char(tty
, '\b');
700 if (ldata
->column
> 0)
706 case ECHO_OP_SET_CANON_COL
:
707 ldata
->canon_column
= ldata
->column
;
711 case ECHO_OP_MOVE_BACK_COL
:
712 if (ldata
->column
> 0)
718 /* This is an escaped echo op start code */
723 tty_put_char(tty
, ECHO_OP_START
);
731 * If the op is not a special byte code,
732 * it is a ctrl char tagged to be echoed
733 * as "^X" (where X is the letter
734 * representing the control char).
735 * Note that we must ensure there is
736 * enough space for the whole ctrl pair.
743 tty_put_char(tty
, '^');
744 tty_put_char(tty
, op
^ 0100);
754 int retval
= do_output_char(c
, tty
, space
);
761 tty_put_char(tty
, c
);
768 /* If the echo buffer is nearly full (so that the possibility exists
769 * of echo overrun before the next commit), then discard enough
770 * data at the tail to prevent a subsequent overrun */
771 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
772 if (echo_buf(ldata
, tail
== ECHO_OP_START
)) {
773 if (echo_buf(ldata
, tail
) == ECHO_OP_ERASE_TAB
)
781 ldata
->echo_tail
= tail
;
782 return old_space
- space
;
785 static void commit_echoes(struct tty_struct
*tty
)
787 struct n_tty_data
*ldata
= tty
->disc_data
;
788 size_t nr
, old
, echoed
;
791 head
= ldata
->echo_head
;
792 old
= ldata
->echo_commit
- ldata
->echo_tail
;
794 /* Process committed echoes if the accumulated # of bytes
795 * is over the threshold (and try again each time another
796 * block is accumulated) */
797 nr
= head
- ldata
->echo_tail
;
798 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
801 mutex_lock(&ldata
->output_lock
);
802 ldata
->echo_commit
= head
;
803 echoed
= __process_echoes(tty
);
804 mutex_unlock(&ldata
->output_lock
);
806 if (echoed
&& tty
->ops
->flush_chars
)
807 tty
->ops
->flush_chars(tty
);
810 static void process_echoes(struct tty_struct
*tty
)
812 struct n_tty_data
*ldata
= tty
->disc_data
;
815 if (!L_ECHO(tty
) || ldata
->echo_commit
== ldata
->echo_tail
)
818 mutex_lock(&ldata
->output_lock
);
819 echoed
= __process_echoes(tty
);
820 mutex_unlock(&ldata
->output_lock
);
822 if (echoed
&& tty
->ops
->flush_chars
)
823 tty
->ops
->flush_chars(tty
);
826 static void flush_echoes(struct tty_struct
*tty
)
828 struct n_tty_data
*ldata
= tty
->disc_data
;
830 if (!L_ECHO(tty
) || ldata
->echo_commit
== ldata
->echo_head
)
833 mutex_lock(&ldata
->output_lock
);
834 ldata
->echo_commit
= ldata
->echo_head
;
835 __process_echoes(tty
);
836 mutex_unlock(&ldata
->output_lock
);
840 * add_echo_byte - add a byte to the echo buffer
841 * @c: unicode byte to echo
844 * Add a character or operation byte to the echo buffer.
847 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
849 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
853 * echo_move_back_col - add operation to move back a column
856 * Add an operation to the echo buffer to move back one column.
859 static void echo_move_back_col(struct n_tty_data
*ldata
)
861 add_echo_byte(ECHO_OP_START
, ldata
);
862 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
866 * echo_set_canon_col - add operation to set the canon column
869 * Add an operation to the echo buffer to set the canon column
870 * to the current column.
873 static void echo_set_canon_col(struct n_tty_data
*ldata
)
875 add_echo_byte(ECHO_OP_START
, ldata
);
876 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
880 * echo_erase_tab - add operation to erase a tab
881 * @num_chars: number of character columns already used
882 * @after_tab: true if num_chars starts after a previous tab
885 * Add an operation to the echo buffer to erase a tab.
887 * Called by the eraser function, which knows how many character
888 * columns have been used since either a previous tab or the start
889 * of input. This information will be used later, along with
890 * canon column (if applicable), to go back the correct number
894 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
895 struct n_tty_data
*ldata
)
897 add_echo_byte(ECHO_OP_START
, ldata
);
898 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
900 /* We only need to know this modulo 8 (tab spacing) */
903 /* Set the high bit as a flag if num_chars is after a previous tab */
907 add_echo_byte(num_chars
, ldata
);
911 * echo_char_raw - echo a character raw
912 * @c: unicode byte to echo
913 * @tty: terminal device
915 * Echo user input back onto the screen. This must be called only when
916 * L_ECHO(tty) is true. Called from the driver receive_buf path.
918 * This variant does not treat control characters specially.
921 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
923 if (c
== ECHO_OP_START
) {
924 add_echo_byte(ECHO_OP_START
, ldata
);
925 add_echo_byte(ECHO_OP_START
, ldata
);
927 add_echo_byte(c
, ldata
);
932 * echo_char - echo a character
933 * @c: unicode byte to echo
934 * @tty: terminal device
936 * Echo user input back onto the screen. This must be called only when
937 * L_ECHO(tty) is true. Called from the driver receive_buf path.
939 * This variant tags control characters to be echoed as "^X"
940 * (where X is the letter representing the control char).
943 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
945 struct n_tty_data
*ldata
= tty
->disc_data
;
947 if (c
== ECHO_OP_START
) {
948 add_echo_byte(ECHO_OP_START
, ldata
);
949 add_echo_byte(ECHO_OP_START
, ldata
);
951 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
952 add_echo_byte(ECHO_OP_START
, ldata
);
953 add_echo_byte(c
, ldata
);
958 * finish_erasing - complete erase
962 static inline void finish_erasing(struct n_tty_data
*ldata
)
964 if (ldata
->erasing
) {
965 echo_char_raw('/', ldata
);
971 * eraser - handle erase function
972 * @c: character input
973 * @tty: terminal device
975 * Perform erase and necessary output when an erase character is
976 * present in the stream from the driver layer. Handles the complexities
977 * of UTF-8 multibyte symbols.
979 * n_tty_receive_buf()/producer path:
980 * caller holds non-exclusive termios_rwsem
983 * Modifying the read_head is not considered a publish in this context
984 * because canonical mode is active -- only canon_head publishes
987 static void eraser(unsigned char c
, struct tty_struct
*tty
)
989 struct n_tty_data
*ldata
= tty
->disc_data
;
990 enum { ERASE
, WERASE
, KILL
} kill_type
;
995 if (ldata
->read_head
== ldata
->canon_head
) {
996 /* process_output('\a', tty); */ /* what do you think? */
999 if (c
== ERASE_CHAR(tty
))
1001 else if (c
== WERASE_CHAR(tty
))
1005 ldata
->read_head
= ldata
->canon_head
;
1008 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1009 ldata
->read_head
= ldata
->canon_head
;
1010 finish_erasing(ldata
);
1011 echo_char(KILL_CHAR(tty
), tty
);
1012 /* Add a newline if ECHOK is on and ECHOKE is off. */
1014 echo_char_raw('\n', ldata
);
1021 while (ldata
->read_head
!= ldata
->canon_head
) {
1022 head
= ldata
->read_head
;
1024 /* erase a single possibly multibyte character */
1027 c
= read_buf(ldata
, head
);
1028 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1030 /* do not partially erase */
1031 if (is_continuation(c
, tty
))
1034 if (kill_type
== WERASE
) {
1035 /* Equivalent to BSD's ALTWERASE. */
1036 if (isalnum(c
) || c
== '_')
1038 else if (seen_alnums
)
1041 cnt
= ldata
->read_head
- head
;
1042 ldata
->read_head
= head
;
1044 if (L_ECHOPRT(tty
)) {
1045 if (!ldata
->erasing
) {
1046 echo_char_raw('\\', ldata
);
1049 /* if cnt > 1, output a multi-byte character */
1053 echo_char_raw(read_buf(ldata
, head
), ldata
);
1054 echo_move_back_col(ldata
);
1056 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1057 echo_char(ERASE_CHAR(tty
), tty
);
1058 } else if (c
== '\t') {
1059 unsigned int num_chars
= 0;
1061 size_t tail
= ldata
->read_head
;
1064 * Count the columns used for characters
1065 * since the start of input or after a
1067 * This info is used to go back the correct
1068 * number of columns.
1070 while (tail
!= ldata
->canon_head
) {
1072 c
= read_buf(ldata
, tail
);
1076 } else if (iscntrl(c
)) {
1079 } else if (!is_continuation(c
, tty
)) {
1083 echo_erase_tab(num_chars
, after_tab
, ldata
);
1085 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1086 echo_char_raw('\b', ldata
);
1087 echo_char_raw(' ', ldata
);
1088 echo_char_raw('\b', ldata
);
1090 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1091 echo_char_raw('\b', ldata
);
1092 echo_char_raw(' ', ldata
);
1093 echo_char_raw('\b', ldata
);
1097 if (kill_type
== ERASE
)
1100 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1101 finish_erasing(ldata
);
1105 * isig - handle the ISIG optio
1109 * Called when a signal is being sent due to terminal input.
1110 * Called from the driver receive_buf path so serialized.
1112 * Locking: ctrl_lock
1115 static inline void isig(int sig
, struct tty_struct
*tty
)
1117 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1119 kill_pgrp(tty_pgrp
, sig
, 1);
1125 * n_tty_receive_break - handle break
1128 * An RS232 break event has been hit in the incoming bitstream. This
1129 * can cause a variety of events depending upon the termios settings.
1131 * n_tty_receive_buf()/producer path:
1132 * caller holds non-exclusive termios_rwsem
1133 * publishes read_head via put_tty_queue()
1135 * Note: may get exclusive termios_rwsem if flushing input buffer
1138 static inline void n_tty_receive_break(struct tty_struct
*tty
)
1140 struct n_tty_data
*ldata
= tty
->disc_data
;
1144 if (I_BRKINT(tty
)) {
1146 if (!L_NOFLSH(tty
)) {
1147 /* flushing needs exclusive termios_rwsem */
1148 up_read(&tty
->termios_rwsem
);
1149 n_tty_flush_buffer(tty
);
1150 tty_driver_flush_buffer(tty
);
1151 down_read(&tty
->termios_rwsem
);
1155 if (I_PARMRK(tty
)) {
1156 put_tty_queue('\377', ldata
);
1157 put_tty_queue('\0', ldata
);
1159 put_tty_queue('\0', ldata
);
1160 wake_up_interruptible(&tty
->read_wait
);
1164 * n_tty_receive_overrun - handle overrun reporting
1167 * Data arrived faster than we could process it. While the tty
1168 * driver has flagged this the bits that were missed are gone
1171 * Called from the receive_buf path so single threaded. Does not
1172 * need locking as num_overrun and overrun_time are function
1176 static inline void n_tty_receive_overrun(struct tty_struct
*tty
)
1178 struct n_tty_data
*ldata
= tty
->disc_data
;
1181 ldata
->num_overrun
++;
1182 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1183 time_after(ldata
->overrun_time
, jiffies
)) {
1184 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1186 ldata
->num_overrun
);
1187 ldata
->overrun_time
= jiffies
;
1188 ldata
->num_overrun
= 0;
1193 * n_tty_receive_parity_error - error notifier
1194 * @tty: terminal device
1197 * Process a parity error and queue the right data to indicate
1198 * the error case if necessary.
1200 * n_tty_receive_buf()/producer path:
1201 * caller holds non-exclusive termios_rwsem
1202 * publishes read_head via put_tty_queue()
1204 static inline void n_tty_receive_parity_error(struct tty_struct
*tty
,
1207 struct n_tty_data
*ldata
= tty
->disc_data
;
1211 if (I_PARMRK(tty
)) {
1212 put_tty_queue('\377', ldata
);
1213 put_tty_queue('\0', ldata
);
1214 put_tty_queue(c
, ldata
);
1215 } else if (I_INPCK(tty
))
1216 put_tty_queue('\0', ldata
);
1218 put_tty_queue(c
, ldata
);
1219 wake_up_interruptible(&tty
->read_wait
);
1223 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1225 if (!L_NOFLSH(tty
)) {
1226 /* flushing needs exclusive termios_rwsem */
1227 up_read(&tty
->termios_rwsem
);
1228 n_tty_flush_buffer(tty
);
1229 tty_driver_flush_buffer(tty
);
1230 down_read(&tty
->termios_rwsem
);
1243 * n_tty_receive_char - perform processing
1244 * @tty: terminal device
1247 * Process an individual character of input received from the driver.
1248 * This is serialized with respect to itself by the rules for the
1251 * n_tty_receive_buf()/producer path:
1252 * caller holds non-exclusive termios_rwsem
1253 * publishes canon_head if canonical mode is active
1254 * otherwise, publishes read_head via put_tty_queue()
1257 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1259 struct n_tty_data
*ldata
= tty
->disc_data
;
1264 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1267 if (L_EXTPROC(tty
)) {
1268 put_tty_queue(c
, ldata
);
1272 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) &&
1273 I_IXANY(tty
) && c
!= START_CHAR(tty
) && c
!= STOP_CHAR(tty
) &&
1274 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) && c
!= SUSP_CHAR(tty
)) {
1276 process_echoes(tty
);
1280 * If the previous character was LNEXT, or we know that this
1281 * character is not one of the characters that we'll have to
1282 * handle specially, do shortcut processing to speed things
1285 if (!test_bit(c
, ldata
->char_map
) || ldata
->lnext
) {
1287 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1288 if (read_cnt(ldata
) >= (N_TTY_BUF_SIZE
- parmrk
- 1)) {
1289 /* beep if no space */
1291 process_output('\a', tty
);
1295 finish_erasing(ldata
);
1296 /* Record the column of first canon char. */
1297 if (ldata
->canon_head
== ldata
->read_head
)
1298 echo_set_canon_col(ldata
);
1303 put_tty_queue(c
, ldata
);
1304 put_tty_queue(c
, ldata
);
1309 if (c
== START_CHAR(tty
)) {
1314 if (c
== STOP_CHAR(tty
)) {
1321 if (c
== INTR_CHAR(tty
)) {
1322 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1324 } else if (c
== QUIT_CHAR(tty
)) {
1325 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1327 } else if (c
== SUSP_CHAR(tty
)) {
1328 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1338 } else if (c
== '\n' && I_INLCR(tty
))
1341 if (ldata
->icanon
) {
1342 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1343 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1348 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1351 finish_erasing(ldata
);
1352 if (L_ECHOCTL(tty
)) {
1353 echo_char_raw('^', ldata
);
1354 echo_char_raw('\b', ldata
);
1360 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
1362 size_t tail
= ldata
->canon_head
;
1364 finish_erasing(ldata
);
1366 echo_char_raw('\n', ldata
);
1367 while (tail
!= ldata
->read_head
) {
1368 echo_char(read_buf(ldata
, tail
), tty
);
1375 if (read_cnt(ldata
) >= N_TTY_BUF_SIZE
) {
1377 process_output('\a', tty
);
1380 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1381 echo_char_raw('\n', ldata
);
1384 goto handle_newline
;
1386 if (c
== EOF_CHAR(tty
)) {
1387 if (read_cnt(ldata
) >= N_TTY_BUF_SIZE
)
1389 c
= __DISABLED_CHAR
;
1390 goto handle_newline
;
1392 if ((c
== EOL_CHAR(tty
)) ||
1393 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1394 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1396 if (read_cnt(ldata
) >= (N_TTY_BUF_SIZE
- parmrk
)) {
1398 process_output('\a', tty
);
1402 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1405 /* Record the column of first canon char. */
1406 if (ldata
->canon_head
== ldata
->read_head
)
1407 echo_set_canon_col(ldata
);
1412 * XXX does PARMRK doubling happen for
1413 * EOL_CHAR and EOL2_CHAR?
1416 put_tty_queue(c
, ldata
);
1419 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1420 put_tty_queue(c
, ldata
);
1421 ldata
->canon_head
= ldata
->read_head
;
1422 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1423 if (waitqueue_active(&tty
->read_wait
))
1424 wake_up_interruptible(&tty
->read_wait
);
1429 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1430 if (read_cnt(ldata
) >= (N_TTY_BUF_SIZE
- parmrk
- 1)) {
1431 /* beep if no space */
1433 process_output('\a', tty
);
1437 finish_erasing(ldata
);
1439 echo_char_raw('\n', ldata
);
1441 /* Record the column of first canon char. */
1442 if (ldata
->canon_head
== ldata
->read_head
)
1443 echo_set_canon_col(ldata
);
1450 put_tty_queue(c
, ldata
);
1452 put_tty_queue(c
, ldata
);
1456 n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1460 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1464 if (c
== STOP_CHAR(tty
))
1466 else if (c
== START_CHAR(tty
) ||
1467 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1468 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1469 c
!= SUSP_CHAR(tty
))) {
1471 process_echoes(tty
);
1477 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1483 n_tty_receive_break(tty
);
1487 n_tty_receive_parity_error(tty
, c
);
1490 n_tty_receive_overrun(tty
);
1493 printk(KERN_ERR
"%s: unknown flag %d\n",
1494 tty_name(tty
, buf
), flag
);
1500 * n_tty_receive_buf - data receive
1501 * @tty: terminal device
1504 * @count: characters
1506 * Called by the terminal driver when a block of characters has
1507 * been received. This function must be called from soft contexts
1508 * not from interrupt context. The driver is responsible for making
1509 * calls one at a time and in order (or using flush_to_ldisc)
1511 * n_tty_receive_buf()/producer path:
1512 * claims non-exclusive termios_rwsem
1513 * publishes read_head and canon_head
1517 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1518 char *fp
, int count
)
1520 struct n_tty_data
*ldata
= tty
->disc_data
;
1523 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1524 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1525 n
= min_t(size_t, count
, n
);
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
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1533 n
= min_t(size_t, count
, n
);
1534 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1535 ldata
->read_head
+= n
;
1539 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1540 char *fp
, int count
)
1542 struct n_tty_data
*ldata
= tty
->disc_data
;
1543 char flag
= TTY_NORMAL
;
1548 if (likely(flag
== TTY_NORMAL
))
1549 put_tty_queue(*cp
++, ldata
);
1551 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1556 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1557 char *fp
, int count
)
1559 char flag
= TTY_NORMAL
;
1564 if (likely(flag
== TTY_NORMAL
))
1565 n_tty_receive_char_closing(tty
, *cp
++);
1567 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1571 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1572 char *fp
, int count
)
1574 struct n_tty_data
*ldata
= tty
->disc_data
;
1575 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1577 if (ldata
->real_raw
)
1578 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1579 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1580 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1581 else if (tty
->closing
&& !L_EXTPROC(tty
))
1582 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1584 char flag
= TTY_NORMAL
;
1589 if (likely(flag
== TTY_NORMAL
))
1590 n_tty_receive_char(tty
, *cp
++);
1592 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1596 if (tty
->ops
->flush_chars
)
1597 tty
->ops
->flush_chars(tty
);
1600 if ((!ldata
->icanon
&& (read_cnt(ldata
) >= ldata
->minimum_to_wake
)) ||
1602 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1603 if (waitqueue_active(&tty
->read_wait
))
1604 wake_up_interruptible(&tty
->read_wait
);
1608 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1609 char *fp
, int count
)
1611 down_read(&tty
->termios_rwsem
);
1612 __receive_buf(tty
, cp
, fp
, count
);
1613 n_tty_check_throttle(tty
);
1614 up_read(&tty
->termios_rwsem
);
1617 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1618 char *fp
, int count
)
1620 struct n_tty_data
*ldata
= tty
->disc_data
;
1623 down_read(&tty
->termios_rwsem
);
1625 tty
->receive_room
= room
= receive_room(tty
);
1628 count
= min(count
, room
);
1630 __receive_buf(tty
, cp
, fp
, count
);
1631 n_tty_check_throttle(tty
);
1634 up_read(&tty
->termios_rwsem
);
1639 int is_ignored(int sig
)
1641 return (sigismember(¤t
->blocked
, sig
) ||
1642 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1646 * n_tty_set_termios - termios data changed
1648 * @old: previous data
1650 * Called by the tty layer when the user changes termios flags so
1651 * that the line discipline can plan ahead. This function cannot sleep
1652 * and is protected from re-entry by the tty layer. The user is
1653 * guaranteed that this function will not be re-entered or in progress
1654 * when the ldisc is closed.
1656 * Locking: Caller holds tty->termios_rwsem
1659 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1661 struct n_tty_data
*ldata
= tty
->disc_data
;
1662 int canon_change
= 1;
1665 canon_change
= (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
;
1667 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1668 ldata
->line_start
= 0;
1669 ldata
->canon_head
= ldata
->read_tail
;
1674 if (canon_change
&& !L_ICANON(tty
) && read_cnt(ldata
))
1675 wake_up_interruptible(&tty
->read_wait
);
1677 ldata
->icanon
= (L_ICANON(tty
) != 0);
1679 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1680 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1681 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1683 bitmap_zero(ldata
->char_map
, 256);
1685 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1686 set_bit('\r', ldata
->char_map
);
1688 set_bit('\n', ldata
->char_map
);
1690 if (L_ICANON(tty
)) {
1691 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1692 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1693 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1694 set_bit('\n', ldata
->char_map
);
1695 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1696 if (L_IEXTEN(tty
)) {
1697 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1698 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1699 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1701 set_bit(REPRINT_CHAR(tty
),
1706 set_bit(START_CHAR(tty
), ldata
->char_map
);
1707 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1710 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1711 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1712 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1714 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1716 ldata
->real_raw
= 0;
1719 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1720 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1721 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1722 ldata
->real_raw
= 1;
1724 ldata
->real_raw
= 0;
1726 n_tty_set_room(tty
);
1728 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1729 * been stopped by STOP_CHAR(tty) before it.
1731 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1735 /* The termios change make the tty ready for I/O */
1736 wake_up_interruptible(&tty
->write_wait
);
1737 wake_up_interruptible(&tty
->read_wait
);
1741 * n_tty_close - close the ldisc for this tty
1744 * Called from the terminal layer when this line discipline is
1745 * being shut down, either because of a close or becsuse of a
1746 * discipline change. The function will not be called while other
1747 * ldisc methods are in progress.
1750 static void n_tty_close(struct tty_struct
*tty
)
1752 struct n_tty_data
*ldata
= tty
->disc_data
;
1755 n_tty_packet_mode_flush(tty
);
1758 tty
->disc_data
= NULL
;
1762 * n_tty_open - open an ldisc
1763 * @tty: terminal to open
1765 * Called when this line discipline is being attached to the
1766 * terminal device. Can sleep. Called serialized so that no
1767 * other events will occur in parallel. No further open will occur
1771 static int n_tty_open(struct tty_struct
*tty
)
1773 struct n_tty_data
*ldata
;
1775 /* Currently a malloc failure here can panic */
1776 ldata
= vmalloc(sizeof(*ldata
));
1780 ldata
->overrun_time
= jiffies
;
1781 mutex_init(&ldata
->atomic_read_lock
);
1782 mutex_init(&ldata
->output_lock
);
1784 tty
->disc_data
= ldata
;
1785 reset_buffer_flags(tty
->disc_data
);
1787 ldata
->canon_column
= 0;
1788 ldata
->minimum_to_wake
= 1;
1789 ldata
->num_overrun
= 0;
1793 /* indicate buffer work may resume */
1794 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1795 n_tty_set_termios(tty
, NULL
);
1796 tty_unthrottle(tty
);
1803 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1805 struct n_tty_data
*ldata
= tty
->disc_data
;
1807 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
1808 if (ldata
->canon_head
!= ldata
->read_tail
)
1810 } else if (read_cnt(ldata
) >= (amt
? amt
: 1))
1817 * copy_from_read_buf - copy read data directly
1818 * @tty: terminal device
1822 * Helper function to speed up n_tty_read. It is only called when
1823 * ICANON is off; it copies characters straight from the tty queue to
1824 * user space directly. It can be profitably called twice; once to
1825 * drain the space from the tail pointer to the (physical) end of the
1826 * buffer, and once to drain the space from the (physical) beginning of
1827 * the buffer to head pointer.
1829 * Called under the ldata->atomic_read_lock sem
1831 * n_tty_read()/consumer path:
1832 * caller holds non-exclusive termios_rwsem
1833 * read_tail published
1836 static int copy_from_read_buf(struct tty_struct
*tty
,
1837 unsigned char __user
**b
,
1841 struct n_tty_data
*ldata
= tty
->disc_data
;
1845 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1848 n
= min(read_cnt(ldata
), N_TTY_BUF_SIZE
- tail
);
1851 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1853 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
1854 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
1856 ldata
->read_tail
+= n
;
1857 /* Turn single EOF into zero-length read */
1858 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&& !read_cnt(ldata
))
1867 * canon_copy_from_read_buf - copy read data in canonical mode
1868 * @tty: terminal device
1872 * Helper function for n_tty_read. It is only called when ICANON is on;
1873 * it copies one line of input up to and including the line-delimiting
1874 * character into the user-space buffer.
1876 * Called under the atomic_read_lock mutex
1878 * n_tty_read()/consumer path:
1879 * caller holds non-exclusive termios_rwsem
1880 * read_tail published
1883 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
1884 unsigned char __user
**b
,
1887 struct n_tty_data
*ldata
= tty
->disc_data
;
1888 size_t n
, size
, more
, c
;
1894 /* N.B. avoid overrun if nr == 0 */
1895 n
= min(*nr
, read_cnt(ldata
));
1899 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1900 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
1902 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1903 __func__
, *nr
, tail
, n
, size
);
1905 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
1906 more
= n
- (size
- tail
);
1907 if (eol
== N_TTY_BUF_SIZE
&& more
) {
1908 /* scan wrapped without finding set bit */
1909 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
1912 } else if (eol
!= size
)
1915 size
= N_TTY_BUF_SIZE
- tail
;
1916 n
= (found
+ eol
+ size
) & (N_TTY_BUF_SIZE
- 1);
1919 if (found
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
1921 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
1924 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
1925 __func__
, eol
, found
, n
, c
, size
, more
);
1928 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), size
);
1931 ret
= copy_to_user(*b
+ size
, ldata
->read_buf
, n
- size
);
1933 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1941 clear_bit(eol
, ldata
->read_flags
);
1942 smp_mb__after_clear_bit();
1943 ldata
->read_tail
+= c
;
1946 ldata
->line_start
= ldata
->read_tail
;
1947 tty_audit_push(tty
);
1949 return eof_push
? -EAGAIN
: 0;
1952 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
1956 * job_control - check job control
1958 * @file: file handle
1960 * Perform job control management checks on this file/tty descriptor
1961 * and if appropriate send any needed signals and return a negative
1962 * error code if action should be taken.
1964 * Locking: redirected write test is safe
1965 * current->signal->tty check is safe
1966 * ctrl_lock to safely reference tty->pgrp
1969 static int job_control(struct tty_struct
*tty
, struct file
*file
)
1971 /* Job control check -- must be done at start and after
1972 every sleep (POSIX.1 7.1.1.4). */
1973 /* NOTE: not yet done after every sleep pending a thorough
1974 check of the logic of this change. -- jlc */
1975 /* don't stop on /dev/console */
1976 if (file
->f_op
->write
== redirected_tty_write
||
1977 current
->signal
->tty
!= tty
)
1980 spin_lock_irq(&tty
->ctrl_lock
);
1982 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
1983 else if (task_pgrp(current
) != tty
->pgrp
) {
1984 spin_unlock_irq(&tty
->ctrl_lock
);
1985 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
1987 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
1988 set_thread_flag(TIF_SIGPENDING
);
1989 return -ERESTARTSYS
;
1991 spin_unlock_irq(&tty
->ctrl_lock
);
1997 * n_tty_read - read function for tty
1999 * @file: file object
2000 * @buf: userspace buffer pointer
2003 * Perform reads for the line discipline. We are guaranteed that the
2004 * line discipline will not be closed under us but we may get multiple
2005 * parallel readers and must handle this ourselves. We may also get
2006 * a hangup. Always called in user context, may sleep.
2008 * This code must be sure never to sleep through a hangup.
2010 * n_tty_read()/consumer path:
2011 * claims non-exclusive termios_rwsem
2012 * publishes read_tail
2015 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2016 unsigned char __user
*buf
, size_t nr
)
2018 struct n_tty_data
*ldata
= tty
->disc_data
;
2019 unsigned char __user
*b
= buf
;
2020 DECLARE_WAITQUEUE(wait
, current
);
2025 unsigned long flags
;
2028 c
= job_control(tty
, file
);
2032 down_read(&tty
->termios_rwsem
);
2035 timeout
= MAX_SCHEDULE_TIMEOUT
;
2036 if (!ldata
->icanon
) {
2037 minimum
= MIN_CHAR(tty
);
2039 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2041 ldata
->minimum_to_wake
= 1;
2042 else if (!waitqueue_active(&tty
->read_wait
) ||
2043 (ldata
->minimum_to_wake
> minimum
))
2044 ldata
->minimum_to_wake
= minimum
;
2046 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2047 ldata
->minimum_to_wake
= minimum
= 1;
2052 * Internal serialization of reads.
2054 if (file
->f_flags
& O_NONBLOCK
) {
2055 if (!mutex_trylock(&ldata
->atomic_read_lock
)) {
2056 up_read(&tty
->termios_rwsem
);
2060 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
)) {
2061 up_read(&tty
->termios_rwsem
);
2062 return -ERESTARTSYS
;
2065 packet
= tty
->packet
;
2067 add_wait_queue(&tty
->read_wait
, &wait
);
2069 /* First test for status change. */
2070 if (packet
&& tty
->link
->ctrl_status
) {
2074 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
2075 cs
= tty
->link
->ctrl_status
;
2076 tty
->link
->ctrl_status
= 0;
2077 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
2078 if (tty_put_user(tty
, cs
, b
++)) {
2086 /* This statement must be first before checking for input
2087 so that any interrupt will set the state back to
2089 set_current_state(TASK_INTERRUPTIBLE
);
2091 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2092 ((minimum
- (b
- buf
)) >= 1))
2093 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2095 if (!input_available_p(tty
, 0)) {
2096 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
2100 if (tty_hung_up_p(file
))
2104 if (file
->f_flags
& O_NONBLOCK
) {
2108 if (signal_pending(current
)) {
2109 retval
= -ERESTARTSYS
;
2112 n_tty_set_room(tty
);
2113 up_read(&tty
->termios_rwsem
);
2115 timeout
= schedule_timeout(timeout
);
2117 down_read(&tty
->termios_rwsem
);
2120 __set_current_state(TASK_RUNNING
);
2122 /* Deal with packet mode. */
2123 if (packet
&& b
== buf
) {
2124 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2132 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2133 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2134 if (retval
== -EAGAIN
) {
2141 /* The copy function takes the read lock and handles
2142 locking internally for this case */
2143 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2144 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2151 n_tty_check_unthrottle(tty
);
2153 if (b
- buf
>= minimum
)
2158 mutex_unlock(&ldata
->atomic_read_lock
);
2159 remove_wait_queue(&tty
->read_wait
, &wait
);
2161 if (!waitqueue_active(&tty
->read_wait
))
2162 ldata
->minimum_to_wake
= minimum
;
2164 __set_current_state(TASK_RUNNING
);
2168 n_tty_set_room(tty
);
2169 up_read(&tty
->termios_rwsem
);
2174 * n_tty_write - write function for tty
2176 * @file: file object
2177 * @buf: userspace buffer pointer
2180 * Write function of the terminal device. This is serialized with
2181 * respect to other write callers but not to termios changes, reads
2182 * and other such events. Since the receive code will echo characters,
2183 * thus calling driver write methods, the output_lock is used in
2184 * the output processing functions called here as well as in the
2185 * echo processing function to protect the column state and space
2186 * left in the buffer.
2188 * This code must be sure never to sleep through a hangup.
2190 * Locking: output_lock to protect column state and space left
2191 * (note that the process_output*() functions take this
2195 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2196 const unsigned char *buf
, size_t nr
)
2198 const unsigned char *b
= buf
;
2199 DECLARE_WAITQUEUE(wait
, current
);
2203 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2204 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2205 retval
= tty_check_change(tty
);
2210 down_read(&tty
->termios_rwsem
);
2212 /* Write out any echoed characters that are still pending */
2213 process_echoes(tty
);
2215 add_wait_queue(&tty
->write_wait
, &wait
);
2217 set_current_state(TASK_INTERRUPTIBLE
);
2218 if (signal_pending(current
)) {
2219 retval
= -ERESTARTSYS
;
2222 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2228 ssize_t num
= process_output_block(tty
, b
, nr
);
2240 if (process_output(c
, tty
) < 0)
2244 if (tty
->ops
->flush_chars
)
2245 tty
->ops
->flush_chars(tty
);
2248 c
= tty
->ops
->write(tty
, b
, nr
);
2261 if (file
->f_flags
& O_NONBLOCK
) {
2265 up_read(&tty
->termios_rwsem
);
2269 down_read(&tty
->termios_rwsem
);
2272 __set_current_state(TASK_RUNNING
);
2273 remove_wait_queue(&tty
->write_wait
, &wait
);
2274 if (b
- buf
!= nr
&& tty
->fasync
)
2275 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2276 up_read(&tty
->termios_rwsem
);
2277 return (b
- buf
) ? b
- buf
: retval
;
2281 * n_tty_poll - poll method for N_TTY
2282 * @tty: terminal device
2283 * @file: file accessing it
2286 * Called when the line discipline is asked to poll() for data or
2287 * for special events. This code is not serialized with respect to
2288 * other events save open/close.
2290 * This code must be sure never to sleep through a hangup.
2291 * Called without the kernel lock held - fine
2294 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2297 struct n_tty_data
*ldata
= tty
->disc_data
;
2298 unsigned int mask
= 0;
2300 poll_wait(file
, &tty
->read_wait
, wait
);
2301 poll_wait(file
, &tty
->write_wait
, wait
);
2302 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
2303 mask
|= POLLIN
| POLLRDNORM
;
2304 if (tty
->packet
&& tty
->link
->ctrl_status
)
2305 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2306 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2308 if (tty_hung_up_p(file
))
2310 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2311 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2312 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2314 ldata
->minimum_to_wake
= 1;
2316 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2317 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2318 tty_write_room(tty
) > 0)
2319 mask
|= POLLOUT
| POLLWRNORM
;
2323 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2325 size_t nr
, head
, tail
;
2327 if (ldata
->canon_head
== ldata
->read_tail
)
2329 head
= ldata
->canon_head
;
2330 tail
= ldata
->read_tail
;
2332 /* Skip EOF-chars.. */
2333 while (head
!= tail
) {
2334 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2335 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2342 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2343 unsigned int cmd
, unsigned long arg
)
2345 struct n_tty_data
*ldata
= tty
->disc_data
;
2350 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2352 down_write(&tty
->termios_rwsem
);
2354 retval
= inq_canon(ldata
);
2356 retval
= read_cnt(ldata
);
2357 up_write(&tty
->termios_rwsem
);
2358 return put_user(retval
, (unsigned int __user
*) arg
);
2360 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2364 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2366 struct n_tty_data
*ldata
= tty
->disc_data
;
2368 if (!waitqueue_active(&tty
->read_wait
)) {
2370 ldata
->minimum_to_wake
= 1;
2371 else if (!tty
->fasync
)
2372 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2376 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2377 .magic
= TTY_LDISC_MAGIC
,
2380 .close
= n_tty_close
,
2381 .flush_buffer
= n_tty_flush_buffer
,
2382 .chars_in_buffer
= n_tty_chars_in_buffer
,
2384 .write
= n_tty_write
,
2385 .ioctl
= n_tty_ioctl
,
2386 .set_termios
= n_tty_set_termios
,
2388 .receive_buf
= n_tty_receive_buf
,
2389 .write_wakeup
= n_tty_write_wakeup
,
2390 .fasync
= n_tty_fasync
,
2391 .receive_buf2
= n_tty_receive_buf2
,
2395 * n_tty_inherit_ops - inherit N_TTY methods
2396 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2398 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2402 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2404 *ops
= tty_ldisc_N_TTY
;
2406 ops
->refcount
= ops
->flags
= 0;
2408 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);