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 */
96 DECLARE_BITMAP(char_map
, 256);
98 /* private to n_tty_receive_overrun (single-threaded) */
99 unsigned long overrun_time
;
105 /* must hold exclusive termios_rwsem to reset these */
106 unsigned char lnext
:1, erasing
:1, raw
:1, real_raw
:1, icanon
:1;
108 /* shared by producer and consumer */
109 char read_buf
[N_TTY_BUF_SIZE
];
110 DECLARE_BITMAP(read_flags
, N_TTY_BUF_SIZE
);
111 unsigned char echo_buf
[N_TTY_BUF_SIZE
];
115 /* consumer-published */
119 /* protected by output lock */
121 unsigned int canon_column
;
124 struct mutex atomic_read_lock
;
125 struct mutex output_lock
;
128 static inline size_t read_cnt(struct n_tty_data
*ldata
)
130 return ldata
->read_head
- ldata
->read_tail
;
133 static inline unsigned char read_buf(struct n_tty_data
*ldata
, size_t i
)
135 return ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
138 static inline unsigned char *read_buf_addr(struct n_tty_data
*ldata
, size_t i
)
140 return &ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
143 static inline unsigned char echo_buf(struct n_tty_data
*ldata
, size_t i
)
145 return ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
148 static inline unsigned char *echo_buf_addr(struct n_tty_data
*ldata
, size_t i
)
150 return &ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
153 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
154 unsigned char __user
*ptr
)
156 struct n_tty_data
*ldata
= tty
->disc_data
;
158 tty_audit_add_data(tty
, &x
, 1, ldata
->icanon
);
159 return put_user(x
, ptr
);
162 static int receive_room(struct tty_struct
*tty
)
164 struct n_tty_data
*ldata
= tty
->disc_data
;
168 /* Multiply read_cnt by 3, since each byte might take up to
169 * three times as many spaces when PARMRK is set (depending on
170 * its flags, e.g. parity error). */
171 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) * 3 - 1;
173 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) - 1;
176 * If we are doing input canonicalization, and there are no
177 * pending newlines, let characters through without limit, so
178 * that erase characters will be handled. Other excess
179 * characters will be beeped.
182 left
= ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
;
188 * n_tty_set_room - receive space
191 * Re-schedules the flip buffer work if space just became available.
193 * Caller holds exclusive termios_rwsem
195 * n_tty_read()/consumer path:
196 * holds non-exclusive termios_rwsem
199 static void n_tty_set_room(struct tty_struct
*tty
)
201 struct n_tty_data
*ldata
= tty
->disc_data
;
203 /* Did this open up the receive buffer? We may need to flip */
204 if (unlikely(ldata
->no_room
) && receive_room(tty
)) {
207 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
208 "scheduling with invalid itty\n");
209 /* see if ldisc has been killed - if so, this means that
210 * even though the ldisc has been halted and ->buf.work
211 * cancelled, ->buf.work is about to be rescheduled
213 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
214 "scheduling buffer work for halted ldisc\n");
215 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
219 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
221 struct n_tty_data
*ldata
= tty
->disc_data
;
227 n
= ldata
->canon_head
- ldata
->read_tail
;
232 * n_tty_write_wakeup - asynchronous I/O notifier
235 * Required for the ptys, serial driver etc. since processes
236 * that attach themselves to the master and rely on ASYNC
237 * IO must be woken up
240 static void n_tty_write_wakeup(struct tty_struct
*tty
)
242 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
243 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
246 static void n_tty_check_throttle(struct tty_struct
*tty
)
248 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
)
251 * Check the remaining room for the input canonicalization
252 * mode. We don't want to throttle the driver if we're in
253 * canonical mode and don't have a newline yet!
257 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
258 if (receive_room(tty
) >= TTY_THRESHOLD_THROTTLE
)
260 throttled
= tty_throttle_safe(tty
);
264 __tty_set_flow_change(tty
, 0);
267 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
269 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
270 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
271 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
276 n_tty_write_wakeup(tty
->link
);
277 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
281 /* If there is enough space in the read buffer now, let the
282 * low-level driver know. We use chars_in_buffer() to
283 * check the buffer, as it now knows about canonical mode.
284 * Otherwise, if the driver is throttled and the line is
285 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
286 * we won't get any more characters.
291 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
292 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
297 unthrottled
= tty_unthrottle_safe(tty
);
301 __tty_set_flow_change(tty
, 0);
305 * put_tty_queue - add character to tty
309 * Add a character to the tty read_buf queue.
311 * n_tty_receive_buf()/producer path:
312 * caller holds non-exclusive termios_rwsem
315 * read_head is only considered 'published' if canonical mode is
319 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
321 *read_buf_addr(ldata
, ldata
->read_head
++) = c
;
325 * reset_buffer_flags - reset buffer state
326 * @tty: terminal to reset
328 * Reset the read buffer counters and clear the flags.
329 * Called from n_tty_open() and n_tty_flush_buffer().
331 * Locking: caller holds exclusive termios_rwsem
332 * (or locking is not required)
335 static void reset_buffer_flags(struct n_tty_data
*ldata
)
337 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
338 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
339 ldata
->line_start
= 0;
342 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
345 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
349 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
350 if (tty
->link
->packet
) {
351 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
352 wake_up_interruptible(&tty
->link
->read_wait
);
354 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
358 * n_tty_flush_buffer - clean input queue
359 * @tty: terminal device
361 * Flush the input buffer. Called when the tty layer wants the
362 * buffer flushed (eg at hangup) or when the N_TTY line discipline
363 * internally has to clean the pending queue (for example some signals).
365 * Holds termios_rwsem to exclude producer/consumer while
366 * buffer indices are reset.
368 * Locking: ctrl_lock, exclusive termios_rwsem
371 static void n_tty_flush_buffer(struct tty_struct
*tty
)
373 down_write(&tty
->termios_rwsem
);
374 reset_buffer_flags(tty
->disc_data
);
378 n_tty_packet_mode_flush(tty
);
379 up_write(&tty
->termios_rwsem
);
383 * n_tty_chars_in_buffer - report available bytes
386 * Report the number of characters buffered to be delivered to user
387 * at this instant in time.
389 * Locking: exclusive termios_rwsem
392 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
396 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
398 down_write(&tty
->termios_rwsem
);
399 n
= chars_in_buffer(tty
);
400 up_write(&tty
->termios_rwsem
);
405 * is_utf8_continuation - utf8 multibyte check
408 * Returns true if the utf8 character 'c' is a multibyte continuation
409 * character. We use this to correctly compute the on screen size
410 * of the character when printing
413 static inline int is_utf8_continuation(unsigned char c
)
415 return (c
& 0xc0) == 0x80;
419 * is_continuation - multibyte check
422 * Returns true if the utf8 character 'c' is a multibyte continuation
423 * character and the terminal is in unicode mode.
426 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
428 return I_IUTF8(tty
) && is_utf8_continuation(c
);
432 * do_output_char - output one character
433 * @c: character (or partial unicode symbol)
434 * @tty: terminal device
435 * @space: space available in tty driver write buffer
437 * This is a helper function that handles one output character
438 * (including special characters like TAB, CR, LF, etc.),
439 * doing OPOST processing and putting the results in the
440 * tty driver's write buffer.
442 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
443 * and NLDLY. They simply aren't relevant in the world today.
444 * If you ever need them, add them here.
446 * Returns the number of bytes of buffer space used or -1 if
449 * Locking: should be called under the output_lock to protect
450 * the column state and space left in the buffer
453 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
455 struct n_tty_data
*ldata
= tty
->disc_data
;
468 ldata
->canon_column
= ldata
->column
= 0;
469 tty
->ops
->write(tty
, "\r\n", 2);
472 ldata
->canon_column
= ldata
->column
;
475 if (O_ONOCR(tty
) && ldata
->column
== 0)
480 ldata
->canon_column
= ldata
->column
= 0;
483 ldata
->canon_column
= ldata
->column
= 0;
486 spaces
= 8 - (ldata
->column
& 7);
487 if (O_TABDLY(tty
) == XTABS
) {
490 ldata
->column
+= spaces
;
491 tty
->ops
->write(tty
, " ", spaces
);
494 ldata
->column
+= spaces
;
497 if (ldata
->column
> 0)
504 if (!is_continuation(c
, tty
))
510 tty_put_char(tty
, c
);
515 * process_output - output post processor
516 * @c: character (or partial unicode symbol)
517 * @tty: terminal device
519 * Output one character with OPOST processing.
520 * Returns -1 when the output device is full and the character
523 * Locking: output_lock to protect column state and space left
524 * (also, this is called from n_tty_write under the
525 * tty layer write lock)
528 static int process_output(unsigned char c
, struct tty_struct
*tty
)
530 struct n_tty_data
*ldata
= tty
->disc_data
;
533 mutex_lock(&ldata
->output_lock
);
535 space
= tty_write_room(tty
);
536 retval
= do_output_char(c
, tty
, space
);
538 mutex_unlock(&ldata
->output_lock
);
546 * process_output_block - block post processor
547 * @tty: terminal device
548 * @buf: character buffer
549 * @nr: number of bytes to output
551 * Output a block of characters with OPOST processing.
552 * Returns the number of characters output.
554 * This path is used to speed up block console writes, among other
555 * things when processing blocks of output data. It handles only
556 * the simple cases normally found and helps to generate blocks of
557 * symbols for the console driver and thus improve performance.
559 * Locking: output_lock to protect column state and space left
560 * (also, this is called from n_tty_write under the
561 * tty layer write lock)
564 static ssize_t
process_output_block(struct tty_struct
*tty
,
565 const unsigned char *buf
, unsigned int nr
)
567 struct n_tty_data
*ldata
= tty
->disc_data
;
570 const unsigned char *cp
;
572 mutex_lock(&ldata
->output_lock
);
574 space
= tty_write_room(tty
);
576 mutex_unlock(&ldata
->output_lock
);
582 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
583 unsigned char c
= *cp
;
591 ldata
->canon_column
= ldata
->column
;
594 if (O_ONOCR(tty
) && ldata
->column
== 0)
598 ldata
->canon_column
= ldata
->column
= 0;
603 if (ldata
->column
> 0)
610 if (!is_continuation(c
, tty
))
617 i
= tty
->ops
->write(tty
, buf
, i
);
619 mutex_unlock(&ldata
->output_lock
);
624 * process_echoes - write pending echo characters
625 * @tty: terminal device
627 * Write previously buffered echo (and other ldisc-generated)
628 * characters to the tty.
630 * Characters generated by the ldisc (including echoes) need to
631 * be buffered because the driver's write buffer can fill during
632 * heavy program output. Echoing straight to the driver will
633 * often fail under these conditions, causing lost characters and
634 * resulting mismatches of ldisc state information.
636 * Since the ldisc state must represent the characters actually sent
637 * to the driver at the time of the write, operations like certain
638 * changes in column state are also saved in the buffer and executed
641 * A circular fifo buffer is used so that the most recent characters
642 * are prioritized. Also, when control characters are echoed with a
643 * prefixed "^", the pair is treated atomically and thus not separated.
645 * Locking: callers must hold output_lock
648 static size_t __process_echoes(struct tty_struct
*tty
)
650 struct n_tty_data
*ldata
= tty
->disc_data
;
651 int space
, old_space
;
655 old_space
= space
= tty_write_room(tty
);
657 tail
= ldata
->echo_tail
;
658 while (ldata
->echo_commit
!= tail
) {
659 c
= echo_buf(ldata
, tail
);
660 if (c
== ECHO_OP_START
) {
662 int no_space_left
= 0;
665 * If the buffer byte is the start of a multi-byte
666 * operation, get the next byte, which is either the
667 * op code or a control character value.
669 op
= echo_buf(ldata
, tail
+ 1);
672 unsigned int num_chars
, num_bs
;
674 case ECHO_OP_ERASE_TAB
:
675 num_chars
= echo_buf(ldata
, tail
+ 2);
678 * Determine how many columns to go back
679 * in order to erase the tab.
680 * This depends on the number of columns
681 * used by other characters within the tab
682 * area. If this (modulo 8) count is from
683 * the start of input rather than from a
684 * previous tab, we offset by canon column.
685 * Otherwise, tab spacing is normal.
687 if (!(num_chars
& 0x80))
688 num_chars
+= ldata
->canon_column
;
689 num_bs
= 8 - (num_chars
& 7);
691 if (num_bs
> space
) {
697 tty_put_char(tty
, '\b');
698 if (ldata
->column
> 0)
704 case ECHO_OP_SET_CANON_COL
:
705 ldata
->canon_column
= ldata
->column
;
709 case ECHO_OP_MOVE_BACK_COL
:
710 if (ldata
->column
> 0)
716 /* This is an escaped echo op start code */
721 tty_put_char(tty
, ECHO_OP_START
);
729 * If the op is not a special byte code,
730 * it is a ctrl char tagged to be echoed
731 * as "^X" (where X is the letter
732 * representing the control char).
733 * Note that we must ensure there is
734 * enough space for the whole ctrl pair.
741 tty_put_char(tty
, '^');
742 tty_put_char(tty
, op
^ 0100);
752 int retval
= do_output_char(c
, tty
, space
);
759 tty_put_char(tty
, c
);
766 /* If the echo buffer is nearly full (so that the possibility exists
767 * of echo overrun before the next commit), then discard enough
768 * data at the tail to prevent a subsequent overrun */
769 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
770 if (echo_buf(ldata
, tail
== ECHO_OP_START
)) {
771 if (echo_buf(ldata
, tail
) == ECHO_OP_ERASE_TAB
)
779 ldata
->echo_tail
= tail
;
780 return old_space
- space
;
783 static void commit_echoes(struct tty_struct
*tty
)
785 struct n_tty_data
*ldata
= tty
->disc_data
;
786 size_t nr
, old
, echoed
;
789 head
= ldata
->echo_head
;
790 old
= ldata
->echo_commit
- ldata
->echo_tail
;
792 /* Process committed echoes if the accumulated # of bytes
793 * is over the threshold (and try again each time another
794 * block is accumulated) */
795 nr
= head
- ldata
->echo_tail
;
796 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
799 mutex_lock(&ldata
->output_lock
);
800 ldata
->echo_commit
= head
;
801 echoed
= __process_echoes(tty
);
802 mutex_unlock(&ldata
->output_lock
);
804 if (echoed
&& tty
->ops
->flush_chars
)
805 tty
->ops
->flush_chars(tty
);
808 static void process_echoes(struct tty_struct
*tty
)
810 struct n_tty_data
*ldata
= tty
->disc_data
;
813 if (!L_ECHO(tty
) || ldata
->echo_commit
== ldata
->echo_tail
)
816 mutex_lock(&ldata
->output_lock
);
817 echoed
= __process_echoes(tty
);
818 mutex_unlock(&ldata
->output_lock
);
820 if (echoed
&& tty
->ops
->flush_chars
)
821 tty
->ops
->flush_chars(tty
);
824 static void flush_echoes(struct tty_struct
*tty
)
826 struct n_tty_data
*ldata
= tty
->disc_data
;
828 if (!L_ECHO(tty
) || ldata
->echo_commit
== ldata
->echo_head
)
831 mutex_lock(&ldata
->output_lock
);
832 ldata
->echo_commit
= ldata
->echo_head
;
833 __process_echoes(tty
);
834 mutex_unlock(&ldata
->output_lock
);
838 * add_echo_byte - add a byte to the echo buffer
839 * @c: unicode byte to echo
842 * Add a character or operation byte to the echo buffer.
845 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
847 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
851 * echo_move_back_col - add operation to move back a column
854 * Add an operation to the echo buffer to move back one column.
857 static void echo_move_back_col(struct n_tty_data
*ldata
)
859 add_echo_byte(ECHO_OP_START
, ldata
);
860 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
864 * echo_set_canon_col - add operation to set the canon column
867 * Add an operation to the echo buffer to set the canon column
868 * to the current column.
871 static void echo_set_canon_col(struct n_tty_data
*ldata
)
873 add_echo_byte(ECHO_OP_START
, ldata
);
874 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
878 * echo_erase_tab - add operation to erase a tab
879 * @num_chars: number of character columns already used
880 * @after_tab: true if num_chars starts after a previous tab
883 * Add an operation to the echo buffer to erase a tab.
885 * Called by the eraser function, which knows how many character
886 * columns have been used since either a previous tab or the start
887 * of input. This information will be used later, along with
888 * canon column (if applicable), to go back the correct number
892 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
893 struct n_tty_data
*ldata
)
895 add_echo_byte(ECHO_OP_START
, ldata
);
896 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
898 /* We only need to know this modulo 8 (tab spacing) */
901 /* Set the high bit as a flag if num_chars is after a previous tab */
905 add_echo_byte(num_chars
, ldata
);
909 * echo_char_raw - echo a character raw
910 * @c: unicode byte to echo
911 * @tty: terminal device
913 * Echo user input back onto the screen. This must be called only when
914 * L_ECHO(tty) is true. Called from the driver receive_buf path.
916 * This variant does not treat control characters specially.
919 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
921 if (c
== ECHO_OP_START
) {
922 add_echo_byte(ECHO_OP_START
, ldata
);
923 add_echo_byte(ECHO_OP_START
, ldata
);
925 add_echo_byte(c
, ldata
);
930 * echo_char - echo a character
931 * @c: unicode byte to echo
932 * @tty: terminal device
934 * Echo user input back onto the screen. This must be called only when
935 * L_ECHO(tty) is true. Called from the driver receive_buf path.
937 * This variant tags control characters to be echoed as "^X"
938 * (where X is the letter representing the control char).
941 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
943 struct n_tty_data
*ldata
= tty
->disc_data
;
945 if (c
== ECHO_OP_START
) {
946 add_echo_byte(ECHO_OP_START
, ldata
);
947 add_echo_byte(ECHO_OP_START
, ldata
);
949 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
950 add_echo_byte(ECHO_OP_START
, ldata
);
951 add_echo_byte(c
, ldata
);
956 * finish_erasing - complete erase
960 static inline void finish_erasing(struct n_tty_data
*ldata
)
962 if (ldata
->erasing
) {
963 echo_char_raw('/', ldata
);
969 * eraser - handle erase function
970 * @c: character input
971 * @tty: terminal device
973 * Perform erase and necessary output when an erase character is
974 * present in the stream from the driver layer. Handles the complexities
975 * of UTF-8 multibyte symbols.
977 * n_tty_receive_buf()/producer path:
978 * caller holds non-exclusive termios_rwsem
981 * Modifying the read_head is not considered a publish in this context
982 * because canonical mode is active -- only canon_head publishes
985 static void eraser(unsigned char c
, struct tty_struct
*tty
)
987 struct n_tty_data
*ldata
= tty
->disc_data
;
988 enum { ERASE
, WERASE
, KILL
} kill_type
;
993 if (ldata
->read_head
== ldata
->canon_head
) {
994 /* process_output('\a', tty); */ /* what do you think? */
997 if (c
== ERASE_CHAR(tty
))
999 else if (c
== WERASE_CHAR(tty
))
1003 ldata
->read_head
= ldata
->canon_head
;
1006 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1007 ldata
->read_head
= ldata
->canon_head
;
1008 finish_erasing(ldata
);
1009 echo_char(KILL_CHAR(tty
), tty
);
1010 /* Add a newline if ECHOK is on and ECHOKE is off. */
1012 echo_char_raw('\n', ldata
);
1019 while (ldata
->read_head
!= ldata
->canon_head
) {
1020 head
= ldata
->read_head
;
1022 /* erase a single possibly multibyte character */
1025 c
= read_buf(ldata
, head
);
1026 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1028 /* do not partially erase */
1029 if (is_continuation(c
, tty
))
1032 if (kill_type
== WERASE
) {
1033 /* Equivalent to BSD's ALTWERASE. */
1034 if (isalnum(c
) || c
== '_')
1036 else if (seen_alnums
)
1039 cnt
= ldata
->read_head
- head
;
1040 ldata
->read_head
= head
;
1042 if (L_ECHOPRT(tty
)) {
1043 if (!ldata
->erasing
) {
1044 echo_char_raw('\\', ldata
);
1047 /* if cnt > 1, output a multi-byte character */
1051 echo_char_raw(read_buf(ldata
, head
), ldata
);
1052 echo_move_back_col(ldata
);
1054 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1055 echo_char(ERASE_CHAR(tty
), tty
);
1056 } else if (c
== '\t') {
1057 unsigned int num_chars
= 0;
1059 size_t tail
= ldata
->read_head
;
1062 * Count the columns used for characters
1063 * since the start of input or after a
1065 * This info is used to go back the correct
1066 * number of columns.
1068 while (tail
!= ldata
->canon_head
) {
1070 c
= read_buf(ldata
, tail
);
1074 } else if (iscntrl(c
)) {
1077 } else if (!is_continuation(c
, tty
)) {
1081 echo_erase_tab(num_chars
, after_tab
, ldata
);
1083 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1084 echo_char_raw('\b', ldata
);
1085 echo_char_raw(' ', ldata
);
1086 echo_char_raw('\b', ldata
);
1088 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1089 echo_char_raw('\b', ldata
);
1090 echo_char_raw(' ', ldata
);
1091 echo_char_raw('\b', ldata
);
1095 if (kill_type
== ERASE
)
1098 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1099 finish_erasing(ldata
);
1103 * isig - handle the ISIG optio
1107 * Called when a signal is being sent due to terminal input.
1108 * Called from the driver receive_buf path so serialized.
1110 * Locking: ctrl_lock
1113 static void isig(int sig
, struct tty_struct
*tty
)
1115 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1117 kill_pgrp(tty_pgrp
, sig
, 1);
1123 * n_tty_receive_break - handle break
1126 * An RS232 break event has been hit in the incoming bitstream. This
1127 * can cause a variety of events depending upon the termios settings.
1129 * n_tty_receive_buf()/producer path:
1130 * caller holds non-exclusive termios_rwsem
1131 * publishes read_head via put_tty_queue()
1133 * Note: may get exclusive termios_rwsem if flushing input buffer
1136 static void n_tty_receive_break(struct tty_struct
*tty
)
1138 struct n_tty_data
*ldata
= tty
->disc_data
;
1142 if (I_BRKINT(tty
)) {
1144 if (!L_NOFLSH(tty
)) {
1145 /* flushing needs exclusive termios_rwsem */
1146 up_read(&tty
->termios_rwsem
);
1147 n_tty_flush_buffer(tty
);
1148 tty_driver_flush_buffer(tty
);
1149 down_read(&tty
->termios_rwsem
);
1153 if (I_PARMRK(tty
)) {
1154 put_tty_queue('\377', ldata
);
1155 put_tty_queue('\0', ldata
);
1157 put_tty_queue('\0', ldata
);
1158 wake_up_interruptible(&tty
->read_wait
);
1162 * n_tty_receive_overrun - handle overrun reporting
1165 * Data arrived faster than we could process it. While the tty
1166 * driver has flagged this the bits that were missed are gone
1169 * Called from the receive_buf path so single threaded. Does not
1170 * need locking as num_overrun and overrun_time are function
1174 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1176 struct n_tty_data
*ldata
= tty
->disc_data
;
1179 ldata
->num_overrun
++;
1180 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1181 time_after(ldata
->overrun_time
, jiffies
)) {
1182 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1184 ldata
->num_overrun
);
1185 ldata
->overrun_time
= jiffies
;
1186 ldata
->num_overrun
= 0;
1191 * n_tty_receive_parity_error - error notifier
1192 * @tty: terminal device
1195 * Process a parity error and queue the right data to indicate
1196 * the error case if necessary.
1198 * n_tty_receive_buf()/producer path:
1199 * caller holds non-exclusive termios_rwsem
1200 * publishes read_head via put_tty_queue()
1202 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1204 struct n_tty_data
*ldata
= tty
->disc_data
;
1208 if (I_PARMRK(tty
)) {
1209 put_tty_queue('\377', ldata
);
1210 put_tty_queue('\0', ldata
);
1211 put_tty_queue(c
, ldata
);
1212 } else if (I_INPCK(tty
))
1213 put_tty_queue('\0', ldata
);
1215 put_tty_queue(c
, ldata
);
1216 wake_up_interruptible(&tty
->read_wait
);
1220 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1222 if (!L_NOFLSH(tty
)) {
1223 /* flushing needs exclusive termios_rwsem */
1224 up_read(&tty
->termios_rwsem
);
1225 n_tty_flush_buffer(tty
);
1226 tty_driver_flush_buffer(tty
);
1227 down_read(&tty
->termios_rwsem
);
1240 * n_tty_receive_char - perform processing
1241 * @tty: terminal device
1244 * Process an individual character of input received from the driver.
1245 * This is serialized with respect to itself by the rules for the
1248 * n_tty_receive_buf()/producer path:
1249 * caller holds non-exclusive termios_rwsem
1250 * publishes canon_head if canonical mode is active
1251 * otherwise, publishes read_head via put_tty_queue()
1255 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1257 struct n_tty_data
*ldata
= tty
->disc_data
;
1261 if (c
== START_CHAR(tty
)) {
1266 if (c
== STOP_CHAR(tty
)) {
1273 if (c
== INTR_CHAR(tty
)) {
1274 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1276 } else if (c
== QUIT_CHAR(tty
)) {
1277 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1279 } else if (c
== SUSP_CHAR(tty
)) {
1280 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1285 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1287 process_echoes(tty
);
1295 } else if (c
== '\n' && I_INLCR(tty
))
1298 if (ldata
->icanon
) {
1299 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1300 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1305 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1308 finish_erasing(ldata
);
1309 if (L_ECHOCTL(tty
)) {
1310 echo_char_raw('^', ldata
);
1311 echo_char_raw('\b', ldata
);
1317 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
1319 size_t tail
= ldata
->canon_head
;
1321 finish_erasing(ldata
);
1323 echo_char_raw('\n', ldata
);
1324 while (tail
!= ldata
->read_head
) {
1325 echo_char(read_buf(ldata
, tail
), tty
);
1332 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1333 echo_char_raw('\n', ldata
);
1336 goto handle_newline
;
1338 if (c
== EOF_CHAR(tty
)) {
1339 c
= __DISABLED_CHAR
;
1340 goto handle_newline
;
1342 if ((c
== EOL_CHAR(tty
)) ||
1343 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1344 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1347 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1350 /* Record the column of first canon char. */
1351 if (ldata
->canon_head
== ldata
->read_head
)
1352 echo_set_canon_col(ldata
);
1357 * XXX does PARMRK doubling happen for
1358 * EOL_CHAR and EOL2_CHAR?
1361 put_tty_queue(c
, ldata
);
1364 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1365 put_tty_queue(c
, ldata
);
1366 ldata
->canon_head
= ldata
->read_head
;
1367 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1368 if (waitqueue_active(&tty
->read_wait
))
1369 wake_up_interruptible(&tty
->read_wait
);
1374 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1376 finish_erasing(ldata
);
1378 echo_char_raw('\n', ldata
);
1380 /* Record the column of first canon char. */
1381 if (ldata
->canon_head
== ldata
->read_head
)
1382 echo_set_canon_col(ldata
);
1389 put_tty_queue(c
, ldata
);
1391 put_tty_queue(c
, ldata
);
1394 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1396 struct n_tty_data
*ldata
= tty
->disc_data
;
1400 * If the previous character was LNEXT, or we know that this
1401 * character is not one of the characters that we'll have to
1402 * handle specially, do shortcut processing to speed things
1405 if (!test_bit(c
, ldata
->char_map
) || ldata
->lnext
) {
1408 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(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
);
1428 n_tty_receive_char_special(tty
, c
);
1432 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1434 struct n_tty_data
*ldata
= tty
->disc_data
;
1437 * If the previous character was LNEXT, or we know that this
1438 * character is not one of the characters that we'll have to
1439 * handle specially, do shortcut processing to speed things
1442 if (!test_bit(c
, ldata
->char_map
) || ldata
->lnext
) {
1445 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) &&
1448 process_echoes(tty
);
1451 finish_erasing(ldata
);
1452 /* Record the column of first canon char. */
1453 if (ldata
->canon_head
== ldata
->read_head
)
1454 echo_set_canon_col(ldata
);
1458 put_tty_queue(c
, ldata
);
1462 n_tty_receive_char_special(tty
, c
);
1466 n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1470 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1474 if (c
== STOP_CHAR(tty
))
1476 else if (c
== START_CHAR(tty
) ||
1477 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1478 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1479 c
!= SUSP_CHAR(tty
))) {
1481 process_echoes(tty
);
1487 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1493 n_tty_receive_break(tty
);
1497 n_tty_receive_parity_error(tty
, c
);
1500 n_tty_receive_overrun(tty
);
1503 printk(KERN_ERR
"%s: unknown flag %d\n",
1504 tty_name(tty
, buf
), flag
);
1510 * n_tty_receive_buf - data receive
1511 * @tty: terminal device
1514 * @count: characters
1516 * Called by the terminal driver when a block of characters has
1517 * been received. This function must be called from soft contexts
1518 * not from interrupt context. The driver is responsible for making
1519 * calls one at a time and in order (or using flush_to_ldisc)
1521 * n_tty_receive_buf()/producer path:
1522 * claims non-exclusive termios_rwsem
1523 * publishes read_head and canon_head
1527 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1528 char *fp
, int count
)
1530 struct n_tty_data
*ldata
= tty
->disc_data
;
1533 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1534 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1535 n
= min_t(size_t, count
, n
);
1536 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1537 ldata
->read_head
+= n
;
1541 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1542 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1543 n
= min_t(size_t, count
, n
);
1544 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1545 ldata
->read_head
+= n
;
1549 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1550 char *fp
, int count
)
1552 struct n_tty_data
*ldata
= tty
->disc_data
;
1553 char flag
= TTY_NORMAL
;
1558 if (likely(flag
== TTY_NORMAL
))
1559 put_tty_queue(*cp
++, ldata
);
1561 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1566 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1567 char *fp
, int count
)
1569 char flag
= TTY_NORMAL
;
1574 if (likely(flag
== TTY_NORMAL
))
1575 n_tty_receive_char_closing(tty
, *cp
++);
1577 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1582 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1583 char *fp
, int count
)
1585 struct n_tty_data
*ldata
= tty
->disc_data
;
1586 char flag
= TTY_NORMAL
;
1591 if (likely(flag
== TTY_NORMAL
)) {
1592 unsigned char c
= *cp
++;
1596 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1598 if (L_EXTPROC(tty
)) {
1599 put_tty_queue(c
, ldata
);
1602 n_tty_receive_char(tty
, c
);
1604 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1609 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1610 char *fp
, int count
)
1612 char flag
= TTY_NORMAL
;
1617 if (likely(flag
== TTY_NORMAL
))
1618 n_tty_receive_char_fast(tty
, *cp
++);
1620 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1624 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1625 char *fp
, int count
)
1627 struct n_tty_data
*ldata
= tty
->disc_data
;
1628 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1630 if (ldata
->real_raw
)
1631 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1632 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1633 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1634 else if (tty
->closing
&& !L_EXTPROC(tty
))
1635 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1637 if (!preops
&& !I_PARMRK(tty
))
1638 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1640 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1643 if (tty
->ops
->flush_chars
)
1644 tty
->ops
->flush_chars(tty
);
1647 if ((!ldata
->icanon
&& (read_cnt(ldata
) >= ldata
->minimum_to_wake
)) ||
1649 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1650 if (waitqueue_active(&tty
->read_wait
))
1651 wake_up_interruptible(&tty
->read_wait
);
1655 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1656 char *fp
, int count
)
1660 down_read(&tty
->termios_rwsem
);
1663 room
= receive_room(tty
);
1664 n
= min(count
, room
);
1667 __receive_buf(tty
, cp
, fp
, n
);
1674 tty
->receive_room
= room
;
1675 n_tty_check_throttle(tty
);
1676 up_read(&tty
->termios_rwsem
);
1679 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1680 char *fp
, int count
)
1682 struct n_tty_data
*ldata
= tty
->disc_data
;
1683 int room
, n
, rcvd
= 0;
1685 down_read(&tty
->termios_rwsem
);
1688 room
= receive_room(tty
);
1689 n
= min(count
, room
);
1695 __receive_buf(tty
, cp
, fp
, n
);
1703 tty
->receive_room
= room
;
1704 n_tty_check_throttle(tty
);
1705 up_read(&tty
->termios_rwsem
);
1710 int is_ignored(int sig
)
1712 return (sigismember(¤t
->blocked
, sig
) ||
1713 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1717 * n_tty_set_termios - termios data changed
1719 * @old: previous data
1721 * Called by the tty layer when the user changes termios flags so
1722 * that the line discipline can plan ahead. This function cannot sleep
1723 * and is protected from re-entry by the tty layer. The user is
1724 * guaranteed that this function will not be re-entered or in progress
1725 * when the ldisc is closed.
1727 * Locking: Caller holds tty->termios_rwsem
1730 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1732 struct n_tty_data
*ldata
= tty
->disc_data
;
1733 int canon_change
= 1;
1736 canon_change
= (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
;
1738 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1739 ldata
->line_start
= 0;
1740 ldata
->canon_head
= ldata
->read_tail
;
1745 if (canon_change
&& !L_ICANON(tty
) && read_cnt(ldata
))
1746 wake_up_interruptible(&tty
->read_wait
);
1748 ldata
->icanon
= (L_ICANON(tty
) != 0);
1750 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1751 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1752 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1754 bitmap_zero(ldata
->char_map
, 256);
1756 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1757 set_bit('\r', ldata
->char_map
);
1759 set_bit('\n', ldata
->char_map
);
1761 if (L_ICANON(tty
)) {
1762 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1763 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1764 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1765 set_bit('\n', ldata
->char_map
);
1766 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1767 if (L_IEXTEN(tty
)) {
1768 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1769 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1770 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1772 set_bit(REPRINT_CHAR(tty
),
1777 set_bit(START_CHAR(tty
), ldata
->char_map
);
1778 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1781 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1782 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1783 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1785 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1787 ldata
->real_raw
= 0;
1790 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1791 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1792 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1793 ldata
->real_raw
= 1;
1795 ldata
->real_raw
= 0;
1797 n_tty_set_room(tty
);
1799 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1800 * been stopped by STOP_CHAR(tty) before it.
1802 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1806 /* The termios change make the tty ready for I/O */
1807 wake_up_interruptible(&tty
->write_wait
);
1808 wake_up_interruptible(&tty
->read_wait
);
1812 * n_tty_close - close the ldisc for this tty
1815 * Called from the terminal layer when this line discipline is
1816 * being shut down, either because of a close or becsuse of a
1817 * discipline change. The function will not be called while other
1818 * ldisc methods are in progress.
1821 static void n_tty_close(struct tty_struct
*tty
)
1823 struct n_tty_data
*ldata
= tty
->disc_data
;
1826 n_tty_packet_mode_flush(tty
);
1829 tty
->disc_data
= NULL
;
1833 * n_tty_open - open an ldisc
1834 * @tty: terminal to open
1836 * Called when this line discipline is being attached to the
1837 * terminal device. Can sleep. Called serialized so that no
1838 * other events will occur in parallel. No further open will occur
1842 static int n_tty_open(struct tty_struct
*tty
)
1844 struct n_tty_data
*ldata
;
1846 /* Currently a malloc failure here can panic */
1847 ldata
= vmalloc(sizeof(*ldata
));
1851 ldata
->overrun_time
= jiffies
;
1852 mutex_init(&ldata
->atomic_read_lock
);
1853 mutex_init(&ldata
->output_lock
);
1855 tty
->disc_data
= ldata
;
1856 reset_buffer_flags(tty
->disc_data
);
1858 ldata
->canon_column
= 0;
1859 ldata
->minimum_to_wake
= 1;
1860 ldata
->num_overrun
= 0;
1864 /* indicate buffer work may resume */
1865 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1866 n_tty_set_termios(tty
, NULL
);
1867 tty_unthrottle(tty
);
1874 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1876 struct n_tty_data
*ldata
= tty
->disc_data
;
1878 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
1879 if (ldata
->canon_head
!= ldata
->read_tail
)
1881 } else if (read_cnt(ldata
) >= (amt
? amt
: 1))
1888 * copy_from_read_buf - copy read data directly
1889 * @tty: terminal device
1893 * Helper function to speed up n_tty_read. It is only called when
1894 * ICANON is off; it copies characters straight from the tty queue to
1895 * user space directly. It can be profitably called twice; once to
1896 * drain the space from the tail pointer to the (physical) end of the
1897 * buffer, and once to drain the space from the (physical) beginning of
1898 * the buffer to head pointer.
1900 * Called under the ldata->atomic_read_lock sem
1902 * n_tty_read()/consumer path:
1903 * caller holds non-exclusive termios_rwsem
1904 * read_tail published
1907 static int copy_from_read_buf(struct tty_struct
*tty
,
1908 unsigned char __user
**b
,
1912 struct n_tty_data
*ldata
= tty
->disc_data
;
1916 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1919 n
= min(read_cnt(ldata
), N_TTY_BUF_SIZE
- tail
);
1922 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1924 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
1925 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
1927 ldata
->read_tail
+= n
;
1928 /* Turn single EOF into zero-length read */
1929 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&& !read_cnt(ldata
))
1938 * canon_copy_from_read_buf - copy read data in canonical mode
1939 * @tty: terminal device
1943 * Helper function for n_tty_read. It is only called when ICANON is on;
1944 * it copies one line of input up to and including the line-delimiting
1945 * character into the user-space buffer.
1947 * Called under the atomic_read_lock mutex
1949 * n_tty_read()/consumer path:
1950 * caller holds non-exclusive termios_rwsem
1951 * read_tail published
1954 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
1955 unsigned char __user
**b
,
1958 struct n_tty_data
*ldata
= tty
->disc_data
;
1959 size_t n
, size
, more
, c
;
1965 /* N.B. avoid overrun if nr == 0 */
1966 n
= min(*nr
, read_cnt(ldata
));
1970 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1971 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
1973 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1974 __func__
, *nr
, tail
, n
, size
);
1976 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
1977 more
= n
- (size
- tail
);
1978 if (eol
== N_TTY_BUF_SIZE
&& more
) {
1979 /* scan wrapped without finding set bit */
1980 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
1983 } else if (eol
!= size
)
1986 size
= N_TTY_BUF_SIZE
- tail
;
1987 n
= (found
+ eol
+ size
) & (N_TTY_BUF_SIZE
- 1);
1990 if (found
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
1992 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
1995 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
1996 __func__
, eol
, found
, n
, c
, size
, more
);
1999 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), size
);
2002 ret
= copy_to_user(*b
+ size
, ldata
->read_buf
, n
- size
);
2004 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2012 clear_bit(eol
, ldata
->read_flags
);
2013 smp_mb__after_clear_bit();
2014 ldata
->read_tail
+= c
;
2017 ldata
->line_start
= ldata
->read_tail
;
2018 tty_audit_push(tty
);
2020 return eof_push
? -EAGAIN
: 0;
2023 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2027 * job_control - check job control
2029 * @file: file handle
2031 * Perform job control management checks on this file/tty descriptor
2032 * and if appropriate send any needed signals and return a negative
2033 * error code if action should be taken.
2035 * Locking: redirected write test is safe
2036 * current->signal->tty check is safe
2037 * ctrl_lock to safely reference tty->pgrp
2040 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2042 /* Job control check -- must be done at start and after
2043 every sleep (POSIX.1 7.1.1.4). */
2044 /* NOTE: not yet done after every sleep pending a thorough
2045 check of the logic of this change. -- jlc */
2046 /* don't stop on /dev/console */
2047 if (file
->f_op
->write
== redirected_tty_write
||
2048 current
->signal
->tty
!= tty
)
2051 spin_lock_irq(&tty
->ctrl_lock
);
2053 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2054 else if (task_pgrp(current
) != tty
->pgrp
) {
2055 spin_unlock_irq(&tty
->ctrl_lock
);
2056 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
2058 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
2059 set_thread_flag(TIF_SIGPENDING
);
2060 return -ERESTARTSYS
;
2062 spin_unlock_irq(&tty
->ctrl_lock
);
2068 * n_tty_read - read function for tty
2070 * @file: file object
2071 * @buf: userspace buffer pointer
2074 * Perform reads for the line discipline. We are guaranteed that the
2075 * line discipline will not be closed under us but we may get multiple
2076 * parallel readers and must handle this ourselves. We may also get
2077 * a hangup. Always called in user context, may sleep.
2079 * This code must be sure never to sleep through a hangup.
2081 * n_tty_read()/consumer path:
2082 * claims non-exclusive termios_rwsem
2083 * publishes read_tail
2086 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2087 unsigned char __user
*buf
, size_t nr
)
2089 struct n_tty_data
*ldata
= tty
->disc_data
;
2090 unsigned char __user
*b
= buf
;
2091 DECLARE_WAITQUEUE(wait
, current
);
2096 unsigned long flags
;
2099 c
= job_control(tty
, file
);
2103 down_read(&tty
->termios_rwsem
);
2106 timeout
= MAX_SCHEDULE_TIMEOUT
;
2107 if (!ldata
->icanon
) {
2108 minimum
= MIN_CHAR(tty
);
2110 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2112 ldata
->minimum_to_wake
= 1;
2113 else if (!waitqueue_active(&tty
->read_wait
) ||
2114 (ldata
->minimum_to_wake
> minimum
))
2115 ldata
->minimum_to_wake
= minimum
;
2117 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2118 ldata
->minimum_to_wake
= minimum
= 1;
2123 * Internal serialization of reads.
2125 if (file
->f_flags
& O_NONBLOCK
) {
2126 if (!mutex_trylock(&ldata
->atomic_read_lock
)) {
2127 up_read(&tty
->termios_rwsem
);
2131 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
)) {
2132 up_read(&tty
->termios_rwsem
);
2133 return -ERESTARTSYS
;
2136 packet
= tty
->packet
;
2138 add_wait_queue(&tty
->read_wait
, &wait
);
2140 /* First test for status change. */
2141 if (packet
&& tty
->link
->ctrl_status
) {
2145 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
2146 cs
= tty
->link
->ctrl_status
;
2147 tty
->link
->ctrl_status
= 0;
2148 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
2149 if (tty_put_user(tty
, cs
, b
++)) {
2157 /* This statement must be first before checking for input
2158 so that any interrupt will set the state back to
2160 set_current_state(TASK_INTERRUPTIBLE
);
2162 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2163 ((minimum
- (b
- buf
)) >= 1))
2164 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2166 if (!input_available_p(tty
, 0)) {
2167 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
2171 if (tty_hung_up_p(file
))
2175 if (file
->f_flags
& O_NONBLOCK
) {
2179 if (signal_pending(current
)) {
2180 retval
= -ERESTARTSYS
;
2183 n_tty_set_room(tty
);
2184 up_read(&tty
->termios_rwsem
);
2186 timeout
= schedule_timeout(timeout
);
2188 down_read(&tty
->termios_rwsem
);
2191 __set_current_state(TASK_RUNNING
);
2193 /* Deal with packet mode. */
2194 if (packet
&& b
== buf
) {
2195 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2203 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2204 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2205 if (retval
== -EAGAIN
) {
2212 /* The copy function takes the read lock and handles
2213 locking internally for this case */
2214 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2215 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2222 n_tty_check_unthrottle(tty
);
2224 if (b
- buf
>= minimum
)
2229 mutex_unlock(&ldata
->atomic_read_lock
);
2230 remove_wait_queue(&tty
->read_wait
, &wait
);
2232 if (!waitqueue_active(&tty
->read_wait
))
2233 ldata
->minimum_to_wake
= minimum
;
2235 __set_current_state(TASK_RUNNING
);
2239 n_tty_set_room(tty
);
2240 up_read(&tty
->termios_rwsem
);
2245 * n_tty_write - write function for tty
2247 * @file: file object
2248 * @buf: userspace buffer pointer
2251 * Write function of the terminal device. This is serialized with
2252 * respect to other write callers but not to termios changes, reads
2253 * and other such events. Since the receive code will echo characters,
2254 * thus calling driver write methods, the output_lock is used in
2255 * the output processing functions called here as well as in the
2256 * echo processing function to protect the column state and space
2257 * left in the buffer.
2259 * This code must be sure never to sleep through a hangup.
2261 * Locking: output_lock to protect column state and space left
2262 * (note that the process_output*() functions take this
2266 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2267 const unsigned char *buf
, size_t nr
)
2269 const unsigned char *b
= buf
;
2270 DECLARE_WAITQUEUE(wait
, current
);
2274 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2275 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2276 retval
= tty_check_change(tty
);
2281 down_read(&tty
->termios_rwsem
);
2283 /* Write out any echoed characters that are still pending */
2284 process_echoes(tty
);
2286 add_wait_queue(&tty
->write_wait
, &wait
);
2288 set_current_state(TASK_INTERRUPTIBLE
);
2289 if (signal_pending(current
)) {
2290 retval
= -ERESTARTSYS
;
2293 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2299 ssize_t num
= process_output_block(tty
, b
, nr
);
2311 if (process_output(c
, tty
) < 0)
2315 if (tty
->ops
->flush_chars
)
2316 tty
->ops
->flush_chars(tty
);
2319 c
= tty
->ops
->write(tty
, b
, nr
);
2332 if (file
->f_flags
& O_NONBLOCK
) {
2336 up_read(&tty
->termios_rwsem
);
2340 down_read(&tty
->termios_rwsem
);
2343 __set_current_state(TASK_RUNNING
);
2344 remove_wait_queue(&tty
->write_wait
, &wait
);
2345 if (b
- buf
!= nr
&& tty
->fasync
)
2346 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2347 up_read(&tty
->termios_rwsem
);
2348 return (b
- buf
) ? b
- buf
: retval
;
2352 * n_tty_poll - poll method for N_TTY
2353 * @tty: terminal device
2354 * @file: file accessing it
2357 * Called when the line discipline is asked to poll() for data or
2358 * for special events. This code is not serialized with respect to
2359 * other events save open/close.
2361 * This code must be sure never to sleep through a hangup.
2362 * Called without the kernel lock held - fine
2365 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2368 struct n_tty_data
*ldata
= tty
->disc_data
;
2369 unsigned int mask
= 0;
2371 poll_wait(file
, &tty
->read_wait
, wait
);
2372 poll_wait(file
, &tty
->write_wait
, wait
);
2373 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
2374 mask
|= POLLIN
| POLLRDNORM
;
2375 if (tty
->packet
&& tty
->link
->ctrl_status
)
2376 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2377 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2379 if (tty_hung_up_p(file
))
2381 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2382 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2383 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2385 ldata
->minimum_to_wake
= 1;
2387 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2388 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2389 tty_write_room(tty
) > 0)
2390 mask
|= POLLOUT
| POLLWRNORM
;
2394 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2396 size_t nr
, head
, tail
;
2398 if (ldata
->canon_head
== ldata
->read_tail
)
2400 head
= ldata
->canon_head
;
2401 tail
= ldata
->read_tail
;
2403 /* Skip EOF-chars.. */
2404 while (head
!= tail
) {
2405 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2406 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2413 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2414 unsigned int cmd
, unsigned long arg
)
2416 struct n_tty_data
*ldata
= tty
->disc_data
;
2421 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2423 down_write(&tty
->termios_rwsem
);
2425 retval
= inq_canon(ldata
);
2427 retval
= read_cnt(ldata
);
2428 up_write(&tty
->termios_rwsem
);
2429 return put_user(retval
, (unsigned int __user
*) arg
);
2431 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2435 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2437 struct n_tty_data
*ldata
= tty
->disc_data
;
2439 if (!waitqueue_active(&tty
->read_wait
)) {
2441 ldata
->minimum_to_wake
= 1;
2442 else if (!tty
->fasync
)
2443 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2447 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2448 .magic
= TTY_LDISC_MAGIC
,
2451 .close
= n_tty_close
,
2452 .flush_buffer
= n_tty_flush_buffer
,
2453 .chars_in_buffer
= n_tty_chars_in_buffer
,
2455 .write
= n_tty_write
,
2456 .ioctl
= n_tty_ioctl
,
2457 .set_termios
= n_tty_set_termios
,
2459 .receive_buf
= n_tty_receive_buf
,
2460 .write_wakeup
= n_tty_write_wakeup
,
2461 .fasync
= n_tty_fasync
,
2462 .receive_buf2
= n_tty_receive_buf2
,
2466 * n_tty_inherit_ops - inherit N_TTY methods
2467 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2469 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2473 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2475 *ops
= tty_ldisc_N_TTY
;
2477 ops
->refcount
= ops
->flags
= 0;
2479 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);