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 */
97 DECLARE_BITMAP(char_map
, 256);
99 /* private to n_tty_receive_overrun (single-threaded) */
100 unsigned long overrun_time
;
106 /* must hold exclusive termios_rwsem to reset these */
107 unsigned char lnext
:1, erasing
:1, raw
:1, real_raw
:1, icanon
:1;
109 /* shared by producer and consumer */
110 char read_buf
[N_TTY_BUF_SIZE
];
111 DECLARE_BITMAP(read_flags
, N_TTY_BUF_SIZE
);
112 unsigned char echo_buf
[N_TTY_BUF_SIZE
];
116 /* consumer-published */
120 /* protected by output lock */
122 unsigned int canon_column
;
125 struct mutex atomic_read_lock
;
126 struct mutex output_lock
;
129 static inline size_t read_cnt(struct n_tty_data
*ldata
)
131 return ldata
->read_head
- ldata
->read_tail
;
134 static inline unsigned char read_buf(struct n_tty_data
*ldata
, size_t i
)
136 return ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
139 static inline unsigned char *read_buf_addr(struct n_tty_data
*ldata
, size_t i
)
141 return &ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
144 static inline unsigned char echo_buf(struct n_tty_data
*ldata
, size_t i
)
146 return ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
149 static inline unsigned char *echo_buf_addr(struct n_tty_data
*ldata
, size_t i
)
151 return &ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
154 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
155 unsigned char __user
*ptr
)
157 struct n_tty_data
*ldata
= tty
->disc_data
;
159 tty_audit_add_data(tty
, &x
, 1, ldata
->icanon
);
160 return put_user(x
, ptr
);
163 static int receive_room(struct tty_struct
*tty
)
165 struct n_tty_data
*ldata
= tty
->disc_data
;
169 /* Multiply read_cnt by 3, since each byte might take up to
170 * three times as many spaces when PARMRK is set (depending on
171 * its flags, e.g. parity error). */
172 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) * 3 - 1;
174 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) - 1;
177 * If we are doing input canonicalization, and there are no
178 * pending newlines, let characters through without limit, so
179 * that erase characters will be handled. Other excess
180 * characters will be beeped.
183 left
= ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
;
189 * n_tty_set_room - receive space
192 * Re-schedules the flip buffer work if space just became available.
194 * Caller holds exclusive termios_rwsem
196 * n_tty_read()/consumer path:
197 * holds non-exclusive termios_rwsem
200 static void n_tty_set_room(struct tty_struct
*tty
)
202 struct n_tty_data
*ldata
= tty
->disc_data
;
204 /* Did this open up the receive buffer? We may need to flip */
205 if (unlikely(ldata
->no_room
) && receive_room(tty
)) {
208 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
209 "scheduling with invalid itty\n");
210 /* see if ldisc has been killed - if so, this means that
211 * even though the ldisc has been halted and ->buf.work
212 * cancelled, ->buf.work is about to be rescheduled
214 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
215 "scheduling buffer work for halted ldisc\n");
216 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
220 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
222 struct n_tty_data
*ldata
= tty
->disc_data
;
228 n
= ldata
->canon_head
- ldata
->read_tail
;
233 * n_tty_write_wakeup - asynchronous I/O notifier
236 * Required for the ptys, serial driver etc. since processes
237 * that attach themselves to the master and rely on ASYNC
238 * IO must be woken up
241 static void n_tty_write_wakeup(struct tty_struct
*tty
)
243 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
244 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
247 static void n_tty_check_throttle(struct tty_struct
*tty
)
249 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
)
252 * Check the remaining room for the input canonicalization
253 * mode. We don't want to throttle the driver if we're in
254 * canonical mode and don't have a newline yet!
258 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
259 if (receive_room(tty
) >= TTY_THRESHOLD_THROTTLE
)
261 throttled
= tty_throttle_safe(tty
);
265 __tty_set_flow_change(tty
, 0);
268 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
270 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
271 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
272 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
277 n_tty_write_wakeup(tty
->link
);
278 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
282 /* If there is enough space in the read buffer now, let the
283 * low-level driver know. We use chars_in_buffer() to
284 * check the buffer, as it now knows about canonical mode.
285 * Otherwise, if the driver is throttled and the line is
286 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
287 * we won't get any more characters.
292 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
293 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
298 unthrottled
= tty_unthrottle_safe(tty
);
302 __tty_set_flow_change(tty
, 0);
306 * put_tty_queue - add character to tty
310 * Add a character to the tty read_buf queue.
312 * n_tty_receive_buf()/producer path:
313 * caller holds non-exclusive termios_rwsem
316 * read_head is only considered 'published' if canonical mode is
320 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
322 *read_buf_addr(ldata
, ldata
->read_head
++) = c
;
326 * reset_buffer_flags - reset buffer state
327 * @tty: terminal to reset
329 * Reset the read buffer counters and clear the flags.
330 * Called from n_tty_open() and n_tty_flush_buffer().
332 * Locking: caller holds exclusive termios_rwsem
333 * (or locking is not required)
336 static void reset_buffer_flags(struct n_tty_data
*ldata
)
338 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
339 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
340 ldata
->echo_mark
= 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
+ 1) == 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 ldata
->echo_mark
= head
;
793 old
= ldata
->echo_commit
- ldata
->echo_tail
;
795 /* Process committed echoes if the accumulated # of bytes
796 * is over the threshold (and try again each time another
797 * block is accumulated) */
798 nr
= head
- ldata
->echo_tail
;
799 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
802 mutex_lock(&ldata
->output_lock
);
803 ldata
->echo_commit
= head
;
804 echoed
= __process_echoes(tty
);
805 mutex_unlock(&ldata
->output_lock
);
807 if (echoed
&& tty
->ops
->flush_chars
)
808 tty
->ops
->flush_chars(tty
);
811 static void process_echoes(struct tty_struct
*tty
)
813 struct n_tty_data
*ldata
= tty
->disc_data
;
816 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
817 ldata
->echo_mark
== ldata
->echo_tail
)
820 mutex_lock(&ldata
->output_lock
);
821 ldata
->echo_commit
= ldata
->echo_mark
;
822 echoed
= __process_echoes(tty
);
823 mutex_unlock(&ldata
->output_lock
);
825 if (echoed
&& tty
->ops
->flush_chars
)
826 tty
->ops
->flush_chars(tty
);
829 /* NB: echo_mark and echo_head should be equivalent here */
830 static void flush_echoes(struct tty_struct
*tty
)
832 struct n_tty_data
*ldata
= tty
->disc_data
;
834 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
835 ldata
->echo_commit
== ldata
->echo_head
)
838 mutex_lock(&ldata
->output_lock
);
839 ldata
->echo_commit
= ldata
->echo_head
;
840 __process_echoes(tty
);
841 mutex_unlock(&ldata
->output_lock
);
845 * add_echo_byte - add a byte to the echo buffer
846 * @c: unicode byte to echo
849 * Add a character or operation byte to the echo buffer.
852 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
854 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
858 * echo_move_back_col - add operation to move back a column
861 * Add an operation to the echo buffer to move back one column.
864 static void echo_move_back_col(struct n_tty_data
*ldata
)
866 add_echo_byte(ECHO_OP_START
, ldata
);
867 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
871 * echo_set_canon_col - add operation to set the canon column
874 * Add an operation to the echo buffer to set the canon column
875 * to the current column.
878 static void echo_set_canon_col(struct n_tty_data
*ldata
)
880 add_echo_byte(ECHO_OP_START
, ldata
);
881 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
885 * echo_erase_tab - add operation to erase a tab
886 * @num_chars: number of character columns already used
887 * @after_tab: true if num_chars starts after a previous tab
890 * Add an operation to the echo buffer to erase a tab.
892 * Called by the eraser function, which knows how many character
893 * columns have been used since either a previous tab or the start
894 * of input. This information will be used later, along with
895 * canon column (if applicable), to go back the correct number
899 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
900 struct n_tty_data
*ldata
)
902 add_echo_byte(ECHO_OP_START
, ldata
);
903 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
905 /* We only need to know this modulo 8 (tab spacing) */
908 /* Set the high bit as a flag if num_chars is after a previous tab */
912 add_echo_byte(num_chars
, ldata
);
916 * echo_char_raw - echo a character raw
917 * @c: unicode byte to echo
918 * @tty: terminal device
920 * Echo user input back onto the screen. This must be called only when
921 * L_ECHO(tty) is true. Called from the driver receive_buf path.
923 * This variant does not treat control characters specially.
926 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
928 if (c
== ECHO_OP_START
) {
929 add_echo_byte(ECHO_OP_START
, ldata
);
930 add_echo_byte(ECHO_OP_START
, ldata
);
932 add_echo_byte(c
, ldata
);
937 * echo_char - echo a character
938 * @c: unicode byte to echo
939 * @tty: terminal device
941 * Echo user input back onto the screen. This must be called only when
942 * L_ECHO(tty) is true. Called from the driver receive_buf path.
944 * This variant tags control characters to be echoed as "^X"
945 * (where X is the letter representing the control char).
948 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
950 struct n_tty_data
*ldata
= tty
->disc_data
;
952 if (c
== ECHO_OP_START
) {
953 add_echo_byte(ECHO_OP_START
, ldata
);
954 add_echo_byte(ECHO_OP_START
, ldata
);
956 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
957 add_echo_byte(ECHO_OP_START
, ldata
);
958 add_echo_byte(c
, ldata
);
963 * finish_erasing - complete erase
967 static inline void finish_erasing(struct n_tty_data
*ldata
)
969 if (ldata
->erasing
) {
970 echo_char_raw('/', ldata
);
976 * eraser - handle erase function
977 * @c: character input
978 * @tty: terminal device
980 * Perform erase and necessary output when an erase character is
981 * present in the stream from the driver layer. Handles the complexities
982 * of UTF-8 multibyte symbols.
984 * n_tty_receive_buf()/producer path:
985 * caller holds non-exclusive termios_rwsem
988 * Modifying the read_head is not considered a publish in this context
989 * because canonical mode is active -- only canon_head publishes
992 static void eraser(unsigned char c
, struct tty_struct
*tty
)
994 struct n_tty_data
*ldata
= tty
->disc_data
;
995 enum { ERASE
, WERASE
, KILL
} kill_type
;
1000 if (ldata
->read_head
== ldata
->canon_head
) {
1001 /* process_output('\a', tty); */ /* what do you think? */
1004 if (c
== ERASE_CHAR(tty
))
1006 else if (c
== WERASE_CHAR(tty
))
1010 ldata
->read_head
= ldata
->canon_head
;
1013 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1014 ldata
->read_head
= ldata
->canon_head
;
1015 finish_erasing(ldata
);
1016 echo_char(KILL_CHAR(tty
), tty
);
1017 /* Add a newline if ECHOK is on and ECHOKE is off. */
1019 echo_char_raw('\n', ldata
);
1026 while (ldata
->read_head
!= ldata
->canon_head
) {
1027 head
= ldata
->read_head
;
1029 /* erase a single possibly multibyte character */
1032 c
= read_buf(ldata
, head
);
1033 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1035 /* do not partially erase */
1036 if (is_continuation(c
, tty
))
1039 if (kill_type
== WERASE
) {
1040 /* Equivalent to BSD's ALTWERASE. */
1041 if (isalnum(c
) || c
== '_')
1043 else if (seen_alnums
)
1046 cnt
= ldata
->read_head
- head
;
1047 ldata
->read_head
= head
;
1049 if (L_ECHOPRT(tty
)) {
1050 if (!ldata
->erasing
) {
1051 echo_char_raw('\\', ldata
);
1054 /* if cnt > 1, output a multi-byte character */
1058 echo_char_raw(read_buf(ldata
, head
), ldata
);
1059 echo_move_back_col(ldata
);
1061 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1062 echo_char(ERASE_CHAR(tty
), tty
);
1063 } else if (c
== '\t') {
1064 unsigned int num_chars
= 0;
1066 size_t tail
= ldata
->read_head
;
1069 * Count the columns used for characters
1070 * since the start of input or after a
1072 * This info is used to go back the correct
1073 * number of columns.
1075 while (tail
!= ldata
->canon_head
) {
1077 c
= read_buf(ldata
, tail
);
1081 } else if (iscntrl(c
)) {
1084 } else if (!is_continuation(c
, tty
)) {
1088 echo_erase_tab(num_chars
, after_tab
, 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
);
1095 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1096 echo_char_raw('\b', ldata
);
1097 echo_char_raw(' ', ldata
);
1098 echo_char_raw('\b', ldata
);
1102 if (kill_type
== ERASE
)
1105 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1106 finish_erasing(ldata
);
1110 * isig - handle the ISIG optio
1114 * Called when a signal is being sent due to terminal input.
1115 * Called from the driver receive_buf path so serialized.
1117 * Locking: ctrl_lock
1120 static void isig(int sig
, struct tty_struct
*tty
)
1122 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1124 kill_pgrp(tty_pgrp
, sig
, 1);
1130 * n_tty_receive_break - handle break
1133 * An RS232 break event has been hit in the incoming bitstream. This
1134 * can cause a variety of events depending upon the termios settings.
1136 * n_tty_receive_buf()/producer path:
1137 * caller holds non-exclusive termios_rwsem
1138 * publishes read_head via put_tty_queue()
1140 * Note: may get exclusive termios_rwsem if flushing input buffer
1143 static void n_tty_receive_break(struct tty_struct
*tty
)
1145 struct n_tty_data
*ldata
= tty
->disc_data
;
1149 if (I_BRKINT(tty
)) {
1151 if (!L_NOFLSH(tty
)) {
1152 /* flushing needs exclusive termios_rwsem */
1153 up_read(&tty
->termios_rwsem
);
1154 n_tty_flush_buffer(tty
);
1155 tty_driver_flush_buffer(tty
);
1156 down_read(&tty
->termios_rwsem
);
1160 if (I_PARMRK(tty
)) {
1161 put_tty_queue('\377', ldata
);
1162 put_tty_queue('\0', ldata
);
1164 put_tty_queue('\0', ldata
);
1165 wake_up_interruptible(&tty
->read_wait
);
1169 * n_tty_receive_overrun - handle overrun reporting
1172 * Data arrived faster than we could process it. While the tty
1173 * driver has flagged this the bits that were missed are gone
1176 * Called from the receive_buf path so single threaded. Does not
1177 * need locking as num_overrun and overrun_time are function
1181 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1183 struct n_tty_data
*ldata
= tty
->disc_data
;
1186 ldata
->num_overrun
++;
1187 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1188 time_after(ldata
->overrun_time
, jiffies
)) {
1189 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1191 ldata
->num_overrun
);
1192 ldata
->overrun_time
= jiffies
;
1193 ldata
->num_overrun
= 0;
1198 * n_tty_receive_parity_error - error notifier
1199 * @tty: terminal device
1202 * Process a parity error and queue the right data to indicate
1203 * the error case if necessary.
1205 * n_tty_receive_buf()/producer path:
1206 * caller holds non-exclusive termios_rwsem
1207 * publishes read_head via put_tty_queue()
1209 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1211 struct n_tty_data
*ldata
= tty
->disc_data
;
1215 if (I_PARMRK(tty
)) {
1216 put_tty_queue('\377', ldata
);
1217 put_tty_queue('\0', ldata
);
1218 put_tty_queue(c
, ldata
);
1219 } else if (I_INPCK(tty
))
1220 put_tty_queue('\0', ldata
);
1222 put_tty_queue(c
, ldata
);
1223 wake_up_interruptible(&tty
->read_wait
);
1227 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1229 if (!L_NOFLSH(tty
)) {
1230 /* flushing needs exclusive termios_rwsem */
1231 up_read(&tty
->termios_rwsem
);
1232 n_tty_flush_buffer(tty
);
1233 tty_driver_flush_buffer(tty
);
1234 down_read(&tty
->termios_rwsem
);
1247 * n_tty_receive_char - perform processing
1248 * @tty: terminal device
1251 * Process an individual character of input received from the driver.
1252 * This is serialized with respect to itself by the rules for the
1255 * n_tty_receive_buf()/producer path:
1256 * caller holds non-exclusive termios_rwsem
1257 * publishes canon_head if canonical mode is active
1258 * otherwise, publishes read_head via put_tty_queue()
1260 * Returns 1 if LNEXT was received, else returns 0
1264 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1266 struct n_tty_data
*ldata
= tty
->disc_data
;
1270 if (c
== START_CHAR(tty
)) {
1275 if (c
== STOP_CHAR(tty
)) {
1282 if (c
== INTR_CHAR(tty
)) {
1283 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1285 } else if (c
== QUIT_CHAR(tty
)) {
1286 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1288 } else if (c
== SUSP_CHAR(tty
)) {
1289 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1294 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1296 process_echoes(tty
);
1304 } else if (c
== '\n' && I_INLCR(tty
))
1307 if (ldata
->icanon
) {
1308 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1309 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1314 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1317 finish_erasing(ldata
);
1318 if (L_ECHOCTL(tty
)) {
1319 echo_char_raw('^', ldata
);
1320 echo_char_raw('\b', ldata
);
1326 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1327 size_t tail
= ldata
->canon_head
;
1329 finish_erasing(ldata
);
1331 echo_char_raw('\n', ldata
);
1332 while (tail
!= ldata
->read_head
) {
1333 echo_char(read_buf(ldata
, tail
), tty
);
1340 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1341 echo_char_raw('\n', ldata
);
1344 goto handle_newline
;
1346 if (c
== EOF_CHAR(tty
)) {
1347 c
= __DISABLED_CHAR
;
1348 goto handle_newline
;
1350 if ((c
== EOL_CHAR(tty
)) ||
1351 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1352 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1355 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1358 /* Record the column of first canon char. */
1359 if (ldata
->canon_head
== ldata
->read_head
)
1360 echo_set_canon_col(ldata
);
1365 * XXX does PARMRK doubling happen for
1366 * EOL_CHAR and EOL2_CHAR?
1369 put_tty_queue(c
, ldata
);
1372 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1373 put_tty_queue(c
, ldata
);
1374 ldata
->canon_head
= ldata
->read_head
;
1375 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1376 if (waitqueue_active(&tty
->read_wait
))
1377 wake_up_interruptible(&tty
->read_wait
);
1382 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1384 finish_erasing(ldata
);
1386 echo_char_raw('\n', ldata
);
1388 /* Record the column of first canon char. */
1389 if (ldata
->canon_head
== ldata
->read_head
)
1390 echo_set_canon_col(ldata
);
1397 put_tty_queue(c
, ldata
);
1399 put_tty_queue(c
, ldata
);
1404 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1406 struct n_tty_data
*ldata
= tty
->disc_data
;
1409 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1411 process_echoes(tty
);
1414 finish_erasing(ldata
);
1415 /* Record the column of first canon char. */
1416 if (ldata
->canon_head
== ldata
->read_head
)
1417 echo_set_canon_col(ldata
);
1421 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1423 put_tty_queue(c
, ldata
);
1424 put_tty_queue(c
, ldata
);
1427 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1429 n_tty_receive_char_inline(tty
, c
);
1433 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1435 struct n_tty_data
*ldata
= tty
->disc_data
;
1437 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1439 process_echoes(tty
);
1442 finish_erasing(ldata
);
1443 /* Record the column of first canon char. */
1444 if (ldata
->canon_head
== ldata
->read_head
)
1445 echo_set_canon_col(ldata
);
1449 put_tty_queue(c
, ldata
);
1453 n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1457 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1461 if (c
== STOP_CHAR(tty
))
1463 else if (c
== START_CHAR(tty
) ||
1464 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1465 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1466 c
!= SUSP_CHAR(tty
))) {
1468 process_echoes(tty
);
1474 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1480 n_tty_receive_break(tty
);
1484 n_tty_receive_parity_error(tty
, c
);
1487 n_tty_receive_overrun(tty
);
1490 printk(KERN_ERR
"%s: unknown flag %d\n",
1491 tty_name(tty
, buf
), flag
);
1497 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1499 struct n_tty_data
*ldata
= tty
->disc_data
;
1502 if (likely(flag
== TTY_NORMAL
)) {
1505 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1507 n_tty_receive_char(tty
, c
);
1509 n_tty_receive_char_flagged(tty
, c
, flag
);
1513 * n_tty_receive_buf - data receive
1514 * @tty: terminal device
1517 * @count: characters
1519 * Called by the terminal driver when a block of characters has
1520 * been received. This function must be called from soft contexts
1521 * not from interrupt context. The driver is responsible for making
1522 * calls one at a time and in order (or using flush_to_ldisc)
1524 * n_tty_receive_buf()/producer path:
1525 * claims non-exclusive termios_rwsem
1526 * publishes read_head and canon_head
1530 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1531 char *fp
, int count
)
1533 struct n_tty_data
*ldata
= tty
->disc_data
;
1536 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1537 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1538 n
= min_t(size_t, count
, n
);
1539 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1540 ldata
->read_head
+= n
;
1544 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1545 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1546 n
= min_t(size_t, count
, n
);
1547 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1548 ldata
->read_head
+= n
;
1552 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1553 char *fp
, int count
)
1555 struct n_tty_data
*ldata
= tty
->disc_data
;
1556 char flag
= TTY_NORMAL
;
1561 if (likely(flag
== TTY_NORMAL
))
1562 put_tty_queue(*cp
++, ldata
);
1564 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1569 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1570 char *fp
, int count
)
1572 char flag
= TTY_NORMAL
;
1577 if (likely(flag
== TTY_NORMAL
))
1578 n_tty_receive_char_closing(tty
, *cp
++);
1580 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1585 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1586 char *fp
, int count
)
1588 struct n_tty_data
*ldata
= tty
->disc_data
;
1589 char flag
= TTY_NORMAL
;
1594 if (likely(flag
== TTY_NORMAL
)) {
1595 unsigned char c
= *cp
++;
1599 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1601 if (L_EXTPROC(tty
)) {
1602 put_tty_queue(c
, ldata
);
1605 if (!test_bit(c
, ldata
->char_map
))
1606 n_tty_receive_char_inline(tty
, c
);
1607 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1610 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1614 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1619 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1620 char *fp
, int count
)
1622 struct n_tty_data
*ldata
= tty
->disc_data
;
1623 char flag
= TTY_NORMAL
;
1628 if (likely(flag
== TTY_NORMAL
)) {
1629 unsigned char c
= *cp
++;
1631 if (!test_bit(c
, ldata
->char_map
))
1632 n_tty_receive_char_fast(tty
, c
);
1633 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1636 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1640 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1644 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1645 char *fp
, int count
)
1647 struct n_tty_data
*ldata
= tty
->disc_data
;
1648 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1650 if (ldata
->real_raw
)
1651 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1652 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1653 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1654 else if (tty
->closing
&& !L_EXTPROC(tty
))
1655 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1658 char flag
= TTY_NORMAL
;
1662 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1666 if (!preops
&& !I_PARMRK(tty
))
1667 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1669 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1672 if (tty
->ops
->flush_chars
)
1673 tty
->ops
->flush_chars(tty
);
1676 if ((!ldata
->icanon
&& (read_cnt(ldata
) >= ldata
->minimum_to_wake
)) ||
1678 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1679 if (waitqueue_active(&tty
->read_wait
))
1680 wake_up_interruptible(&tty
->read_wait
);
1684 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1685 char *fp
, int count
)
1689 down_read(&tty
->termios_rwsem
);
1692 room
= receive_room(tty
);
1693 n
= min(count
, room
);
1696 __receive_buf(tty
, cp
, fp
, n
);
1703 tty
->receive_room
= room
;
1704 n_tty_check_throttle(tty
);
1705 up_read(&tty
->termios_rwsem
);
1708 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1709 char *fp
, int count
)
1711 struct n_tty_data
*ldata
= tty
->disc_data
;
1712 int room
, n
, rcvd
= 0;
1714 down_read(&tty
->termios_rwsem
);
1717 room
= receive_room(tty
);
1718 n
= min(count
, room
);
1724 __receive_buf(tty
, cp
, fp
, n
);
1732 tty
->receive_room
= room
;
1733 n_tty_check_throttle(tty
);
1734 up_read(&tty
->termios_rwsem
);
1739 int is_ignored(int sig
)
1741 return (sigismember(¤t
->blocked
, sig
) ||
1742 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1746 * n_tty_set_termios - termios data changed
1748 * @old: previous data
1750 * Called by the tty layer when the user changes termios flags so
1751 * that the line discipline can plan ahead. This function cannot sleep
1752 * and is protected from re-entry by the tty layer. The user is
1753 * guaranteed that this function will not be re-entered or in progress
1754 * when the ldisc is closed.
1756 * Locking: Caller holds tty->termios_rwsem
1759 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1761 struct n_tty_data
*ldata
= tty
->disc_data
;
1763 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1764 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1765 ldata
->line_start
= ldata
->canon_head
= ldata
->read_tail
;
1770 ldata
->icanon
= (L_ICANON(tty
) != 0);
1772 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1773 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1774 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1776 bitmap_zero(ldata
->char_map
, 256);
1778 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1779 set_bit('\r', ldata
->char_map
);
1781 set_bit('\n', ldata
->char_map
);
1783 if (L_ICANON(tty
)) {
1784 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1785 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1786 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1787 set_bit('\n', ldata
->char_map
);
1788 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1789 if (L_IEXTEN(tty
)) {
1790 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1791 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1792 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1794 set_bit(REPRINT_CHAR(tty
),
1799 set_bit(START_CHAR(tty
), ldata
->char_map
);
1800 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1803 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1804 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1805 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1807 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1809 ldata
->real_raw
= 0;
1812 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1813 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1814 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1815 ldata
->real_raw
= 1;
1817 ldata
->real_raw
= 0;
1819 n_tty_set_room(tty
);
1821 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1822 * been stopped by STOP_CHAR(tty) before it.
1824 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
)
1827 /* The termios change make the tty ready for I/O */
1828 wake_up_interruptible(&tty
->write_wait
);
1829 wake_up_interruptible(&tty
->read_wait
);
1833 * n_tty_close - close the ldisc for this tty
1836 * Called from the terminal layer when this line discipline is
1837 * being shut down, either because of a close or becsuse of a
1838 * discipline change. The function will not be called while other
1839 * ldisc methods are in progress.
1842 static void n_tty_close(struct tty_struct
*tty
)
1844 struct n_tty_data
*ldata
= tty
->disc_data
;
1847 n_tty_packet_mode_flush(tty
);
1850 tty
->disc_data
= NULL
;
1854 * n_tty_open - open an ldisc
1855 * @tty: terminal to open
1857 * Called when this line discipline is being attached to the
1858 * terminal device. Can sleep. Called serialized so that no
1859 * other events will occur in parallel. No further open will occur
1863 static int n_tty_open(struct tty_struct
*tty
)
1865 struct n_tty_data
*ldata
;
1867 /* Currently a malloc failure here can panic */
1868 ldata
= vmalloc(sizeof(*ldata
));
1872 ldata
->overrun_time
= jiffies
;
1873 mutex_init(&ldata
->atomic_read_lock
);
1874 mutex_init(&ldata
->output_lock
);
1876 tty
->disc_data
= ldata
;
1877 reset_buffer_flags(tty
->disc_data
);
1879 ldata
->canon_column
= 0;
1880 ldata
->minimum_to_wake
= 1;
1881 ldata
->num_overrun
= 0;
1885 /* indicate buffer work may resume */
1886 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1887 n_tty_set_termios(tty
, NULL
);
1888 tty_unthrottle(tty
);
1895 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1897 struct n_tty_data
*ldata
= tty
->disc_data
;
1899 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
1900 if (ldata
->canon_head
!= ldata
->read_tail
)
1902 } else if (read_cnt(ldata
) >= (amt
? amt
: 1))
1909 * copy_from_read_buf - copy read data directly
1910 * @tty: terminal device
1914 * Helper function to speed up n_tty_read. It is only called when
1915 * ICANON is off; it copies characters straight from the tty queue to
1916 * user space directly. It can be profitably called twice; once to
1917 * drain the space from the tail pointer to the (physical) end of the
1918 * buffer, and once to drain the space from the (physical) beginning of
1919 * the buffer to head pointer.
1921 * Called under the ldata->atomic_read_lock sem
1923 * n_tty_read()/consumer path:
1924 * caller holds non-exclusive termios_rwsem
1925 * read_tail published
1928 static int copy_from_read_buf(struct tty_struct
*tty
,
1929 unsigned char __user
**b
,
1933 struct n_tty_data
*ldata
= tty
->disc_data
;
1937 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1940 n
= min(read_cnt(ldata
), N_TTY_BUF_SIZE
- tail
);
1943 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1945 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
1946 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
1948 ldata
->read_tail
+= n
;
1949 /* Turn single EOF into zero-length read */
1950 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&& !read_cnt(ldata
))
1959 * canon_copy_from_read_buf - copy read data in canonical mode
1960 * @tty: terminal device
1964 * Helper function for n_tty_read. It is only called when ICANON is on;
1965 * it copies one line of input up to and including the line-delimiting
1966 * character into the user-space buffer.
1968 * Called under the atomic_read_lock mutex
1970 * n_tty_read()/consumer path:
1971 * caller holds non-exclusive termios_rwsem
1972 * read_tail published
1975 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
1976 unsigned char __user
**b
,
1979 struct n_tty_data
*ldata
= tty
->disc_data
;
1980 size_t n
, size
, more
, c
;
1986 /* N.B. avoid overrun if nr == 0 */
1987 n
= min(*nr
, read_cnt(ldata
));
1991 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1992 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
1994 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1995 __func__
, *nr
, tail
, n
, size
);
1997 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
1998 more
= n
- (size
- tail
);
1999 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2000 /* scan wrapped without finding set bit */
2001 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2004 } else if (eol
!= size
)
2007 size
= N_TTY_BUF_SIZE
- tail
;
2014 if (found
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
2016 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
2019 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2020 __func__
, eol
, found
, n
, c
, size
, more
);
2023 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), size
);
2026 ret
= copy_to_user(*b
+ size
, ldata
->read_buf
, n
- size
);
2028 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2036 clear_bit(eol
, ldata
->read_flags
);
2037 smp_mb__after_clear_bit();
2038 ldata
->read_tail
+= c
;
2041 ldata
->line_start
= ldata
->read_tail
;
2042 tty_audit_push(tty
);
2044 return eof_push
? -EAGAIN
: 0;
2047 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2051 * job_control - check job control
2053 * @file: file handle
2055 * Perform job control management checks on this file/tty descriptor
2056 * and if appropriate send any needed signals and return a negative
2057 * error code if action should be taken.
2059 * Locking: redirected write test is safe
2060 * current->signal->tty check is safe
2061 * ctrl_lock to safely reference tty->pgrp
2064 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2066 /* Job control check -- must be done at start and after
2067 every sleep (POSIX.1 7.1.1.4). */
2068 /* NOTE: not yet done after every sleep pending a thorough
2069 check of the logic of this change. -- jlc */
2070 /* don't stop on /dev/console */
2071 if (file
->f_op
->write
== redirected_tty_write
||
2072 current
->signal
->tty
!= tty
)
2075 spin_lock_irq(&tty
->ctrl_lock
);
2077 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2078 else if (task_pgrp(current
) != tty
->pgrp
) {
2079 spin_unlock_irq(&tty
->ctrl_lock
);
2080 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
2082 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
2083 set_thread_flag(TIF_SIGPENDING
);
2084 return -ERESTARTSYS
;
2086 spin_unlock_irq(&tty
->ctrl_lock
);
2092 * n_tty_read - read function for tty
2094 * @file: file object
2095 * @buf: userspace buffer pointer
2098 * Perform reads for the line discipline. We are guaranteed that the
2099 * line discipline will not be closed under us but we may get multiple
2100 * parallel readers and must handle this ourselves. We may also get
2101 * a hangup. Always called in user context, may sleep.
2103 * This code must be sure never to sleep through a hangup.
2105 * n_tty_read()/consumer path:
2106 * claims non-exclusive termios_rwsem
2107 * publishes read_tail
2110 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2111 unsigned char __user
*buf
, size_t nr
)
2113 struct n_tty_data
*ldata
= tty
->disc_data
;
2114 unsigned char __user
*b
= buf
;
2115 DECLARE_WAITQUEUE(wait
, current
);
2120 unsigned long flags
;
2123 c
= job_control(tty
, file
);
2128 * Internal serialization of reads.
2130 if (file
->f_flags
& O_NONBLOCK
) {
2131 if (!mutex_trylock(&ldata
->atomic_read_lock
))
2134 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
))
2135 return -ERESTARTSYS
;
2138 down_read(&tty
->termios_rwsem
);
2141 timeout
= MAX_SCHEDULE_TIMEOUT
;
2142 if (!ldata
->icanon
) {
2143 minimum
= MIN_CHAR(tty
);
2145 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2147 ldata
->minimum_to_wake
= 1;
2148 else if (!waitqueue_active(&tty
->read_wait
) ||
2149 (ldata
->minimum_to_wake
> minimum
))
2150 ldata
->minimum_to_wake
= minimum
;
2152 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2153 ldata
->minimum_to_wake
= minimum
= 1;
2157 packet
= tty
->packet
;
2159 add_wait_queue(&tty
->read_wait
, &wait
);
2161 /* First test for status change. */
2162 if (packet
&& tty
->link
->ctrl_status
) {
2166 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
2167 cs
= tty
->link
->ctrl_status
;
2168 tty
->link
->ctrl_status
= 0;
2169 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
2170 if (tty_put_user(tty
, cs
, b
++)) {
2178 /* This statement must be first before checking for input
2179 so that any interrupt will set the state back to
2181 set_current_state(TASK_INTERRUPTIBLE
);
2183 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2184 ((minimum
- (b
- buf
)) >= 1))
2185 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2187 if (!input_available_p(tty
, 0)) {
2188 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
2189 up_read(&tty
->termios_rwsem
);
2190 tty_flush_to_ldisc(tty
);
2191 down_read(&tty
->termios_rwsem
);
2192 if (!input_available_p(tty
, 0)) {
2197 if (tty_hung_up_p(file
))
2201 if (file
->f_flags
& O_NONBLOCK
) {
2205 if (signal_pending(current
)) {
2206 retval
= -ERESTARTSYS
;
2209 n_tty_set_room(tty
);
2210 up_read(&tty
->termios_rwsem
);
2212 timeout
= schedule_timeout(timeout
);
2214 down_read(&tty
->termios_rwsem
);
2218 __set_current_state(TASK_RUNNING
);
2220 /* Deal with packet mode. */
2221 if (packet
&& b
== buf
) {
2222 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2230 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2231 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2232 if (retval
== -EAGAIN
) {
2239 /* The copy function takes the read lock and handles
2240 locking internally for this case */
2241 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2242 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2249 n_tty_check_unthrottle(tty
);
2251 if (b
- buf
>= minimum
)
2256 n_tty_set_room(tty
);
2257 up_read(&tty
->termios_rwsem
);
2259 remove_wait_queue(&tty
->read_wait
, &wait
);
2260 if (!waitqueue_active(&tty
->read_wait
))
2261 ldata
->minimum_to_wake
= minimum
;
2263 mutex_unlock(&ldata
->atomic_read_lock
);
2265 __set_current_state(TASK_RUNNING
);
2273 * n_tty_write - write function for tty
2275 * @file: file object
2276 * @buf: userspace buffer pointer
2279 * Write function of the terminal device. This is serialized with
2280 * respect to other write callers but not to termios changes, reads
2281 * and other such events. Since the receive code will echo characters,
2282 * thus calling driver write methods, the output_lock is used in
2283 * the output processing functions called here as well as in the
2284 * echo processing function to protect the column state and space
2285 * left in the buffer.
2287 * This code must be sure never to sleep through a hangup.
2289 * Locking: output_lock to protect column state and space left
2290 * (note that the process_output*() functions take this
2294 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2295 const unsigned char *buf
, size_t nr
)
2297 const unsigned char *b
= buf
;
2298 DECLARE_WAITQUEUE(wait
, current
);
2302 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2303 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2304 retval
= tty_check_change(tty
);
2309 down_read(&tty
->termios_rwsem
);
2311 /* Write out any echoed characters that are still pending */
2312 process_echoes(tty
);
2314 add_wait_queue(&tty
->write_wait
, &wait
);
2316 set_current_state(TASK_INTERRUPTIBLE
);
2317 if (signal_pending(current
)) {
2318 retval
= -ERESTARTSYS
;
2321 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2327 ssize_t num
= process_output_block(tty
, b
, nr
);
2339 if (process_output(c
, tty
) < 0)
2343 if (tty
->ops
->flush_chars
)
2344 tty
->ops
->flush_chars(tty
);
2347 c
= tty
->ops
->write(tty
, b
, nr
);
2360 if (file
->f_flags
& O_NONBLOCK
) {
2364 up_read(&tty
->termios_rwsem
);
2368 down_read(&tty
->termios_rwsem
);
2371 __set_current_state(TASK_RUNNING
);
2372 remove_wait_queue(&tty
->write_wait
, &wait
);
2373 if (b
- buf
!= nr
&& tty
->fasync
)
2374 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2375 up_read(&tty
->termios_rwsem
);
2376 return (b
- buf
) ? b
- buf
: retval
;
2380 * n_tty_poll - poll method for N_TTY
2381 * @tty: terminal device
2382 * @file: file accessing it
2385 * Called when the line discipline is asked to poll() for data or
2386 * for special events. This code is not serialized with respect to
2387 * other events save open/close.
2389 * This code must be sure never to sleep through a hangup.
2390 * Called without the kernel lock held - fine
2393 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2396 struct n_tty_data
*ldata
= tty
->disc_data
;
2397 unsigned int mask
= 0;
2399 poll_wait(file
, &tty
->read_wait
, wait
);
2400 poll_wait(file
, &tty
->write_wait
, wait
);
2401 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
2402 mask
|= POLLIN
| POLLRDNORM
;
2403 if (tty
->packet
&& tty
->link
->ctrl_status
)
2404 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2405 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2407 if (tty_hung_up_p(file
))
2409 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2410 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2411 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2413 ldata
->minimum_to_wake
= 1;
2415 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2416 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2417 tty_write_room(tty
) > 0)
2418 mask
|= POLLOUT
| POLLWRNORM
;
2422 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2424 size_t nr
, head
, tail
;
2426 if (ldata
->canon_head
== ldata
->read_tail
)
2428 head
= ldata
->canon_head
;
2429 tail
= ldata
->read_tail
;
2431 /* Skip EOF-chars.. */
2432 while (head
!= tail
) {
2433 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2434 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2441 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2442 unsigned int cmd
, unsigned long arg
)
2444 struct n_tty_data
*ldata
= tty
->disc_data
;
2449 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2451 down_write(&tty
->termios_rwsem
);
2453 retval
= inq_canon(ldata
);
2455 retval
= read_cnt(ldata
);
2456 up_write(&tty
->termios_rwsem
);
2457 return put_user(retval
, (unsigned int __user
*) arg
);
2459 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2463 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2465 struct n_tty_data
*ldata
= tty
->disc_data
;
2467 if (!waitqueue_active(&tty
->read_wait
)) {
2469 ldata
->minimum_to_wake
= 1;
2470 else if (!tty
->fasync
)
2471 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2475 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2476 .magic
= TTY_LDISC_MAGIC
,
2479 .close
= n_tty_close
,
2480 .flush_buffer
= n_tty_flush_buffer
,
2481 .chars_in_buffer
= n_tty_chars_in_buffer
,
2483 .write
= n_tty_write
,
2484 .ioctl
= n_tty_ioctl
,
2485 .set_termios
= n_tty_set_termios
,
2487 .receive_buf
= n_tty_receive_buf
,
2488 .write_wakeup
= n_tty_write_wakeup
,
2489 .fasync
= n_tty_fasync
,
2490 .receive_buf2
= n_tty_receive_buf2
,
2494 * n_tty_inherit_ops - inherit N_TTY methods
2495 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2497 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2501 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2503 *ops
= tty_ldisc_N_TTY
;
2505 ops
->refcount
= ops
->flags
= 0;
2507 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);