2 * n_tty.c --- implements the N_TTY line discipline.
4 * This code used to be in tty_io.c, but things are getting hairy
5 * enough that it made sense to split things off. (The N_TTY
6 * processing has changed so much that it's hardly recognizable,
9 * Note that the open routine for N_TTY is guaranteed never to return
10 * an error. This is because Linux will fall back to setting a line
11 * to N_TTY if it can not switch to any other line discipline.
13 * Written by Theodore Ts'o, Copyright 1994.
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18 * This file may be redistributed under the terms of the GNU General Public
21 * Reduced memory usage for older ARM systems - Russell King.
23 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
24 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25 * who actually finally proved there really was a race.
27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29 * Also fixed a bug in BLOCKING mode where n_tty_write returns
33 #include <linux/types.h>
34 #include <linux/major.h>
35 #include <linux/errno.h>
36 #include <linux/signal.h>
37 #include <linux/fcntl.h>
38 #include <linux/sched.h>
39 #include <linux/interrupt.h>
40 #include <linux/tty.h>
41 #include <linux/timer.h>
42 #include <linux/ctype.h>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
48 #include <linux/audit.h>
49 #include <linux/file.h>
50 #include <linux/uaccess.h>
51 #include <linux/module.h>
52 #include <linux/ratelimit.h>
53 #include <linux/vmalloc.h>
56 /* number of characters left in xmit buffer before select has we have room */
57 #define WAKEUP_CHARS 256
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
64 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65 #define TTY_THRESHOLD_UNTHROTTLE 128
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
73 #define ECHO_OP_START 0xff
74 #define ECHO_OP_MOVE_BACK_COL 0x80
75 #define ECHO_OP_SET_CANON_COL 0x81
76 #define ECHO_OP_ERASE_TAB 0x82
78 #define ECHO_COMMIT_WATERMARK 256
79 #define ECHO_BLOCK 256
80 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
85 # define n_tty_trace(f, args...) trace_printk(f, ##args)
87 # define n_tty_trace(f, args...)
91 /* producer-published */
98 DECLARE_BITMAP(char_map
, 256);
100 /* private to n_tty_receive_overrun (single-threaded) */
101 unsigned long overrun_time
;
107 /* must hold exclusive termios_rwsem to reset these */
108 unsigned char lnext
:1, erasing
:1, raw
:1, real_raw
:1, icanon
:1;
109 unsigned char push
:1;
111 /* shared by producer and consumer */
112 char read_buf
[N_TTY_BUF_SIZE
];
113 DECLARE_BITMAP(read_flags
, N_TTY_BUF_SIZE
);
114 unsigned char echo_buf
[N_TTY_BUF_SIZE
];
118 /* consumer-published */
122 /* protected by output lock */
124 unsigned int canon_column
;
127 struct mutex atomic_read_lock
;
128 struct mutex output_lock
;
131 static inline size_t read_cnt(struct n_tty_data
*ldata
)
133 return ldata
->read_head
- ldata
->read_tail
;
136 static inline unsigned char read_buf(struct n_tty_data
*ldata
, size_t i
)
138 return ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
141 static inline unsigned char *read_buf_addr(struct n_tty_data
*ldata
, size_t i
)
143 return &ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
146 static inline unsigned char echo_buf(struct n_tty_data
*ldata
, size_t i
)
148 return ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
151 static inline unsigned char *echo_buf_addr(struct n_tty_data
*ldata
, size_t i
)
153 return &ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
156 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
157 unsigned char __user
*ptr
)
159 struct n_tty_data
*ldata
= tty
->disc_data
;
161 tty_audit_add_data(tty
, &x
, 1, ldata
->icanon
);
162 return put_user(x
, ptr
);
165 static inline int tty_copy_to_user(struct tty_struct
*tty
,
170 struct n_tty_data
*ldata
= tty
->disc_data
;
172 tty_audit_add_data(tty
, from
, n
, ldata
->icanon
);
173 return copy_to_user(to
, from
, n
);
177 * n_tty_kick_worker - start input worker (if required)
180 * Re-schedules the flip buffer work if it may have stopped
182 * Caller holds exclusive termios_rwsem
184 * n_tty_read()/consumer path:
185 * holds non-exclusive termios_rwsem
188 static void n_tty_kick_worker(struct tty_struct
*tty
)
190 struct n_tty_data
*ldata
= tty
->disc_data
;
192 /* Did the input worker stop? Restart it */
193 if (unlikely(ldata
->no_room
)) {
196 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
197 "scheduling with invalid itty\n");
198 /* see if ldisc has been killed - if so, this means that
199 * even though the ldisc has been halted and ->buf.work
200 * cancelled, ->buf.work is about to be rescheduled
202 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
203 "scheduling buffer work for halted ldisc\n");
204 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
208 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
210 struct n_tty_data
*ldata
= tty
->disc_data
;
214 n
= ldata
->commit_head
- ldata
->read_tail
;
216 n
= ldata
->canon_head
- ldata
->read_tail
;
221 * n_tty_write_wakeup - asynchronous I/O notifier
224 * Required for the ptys, serial driver etc. since processes
225 * that attach themselves to the master and rely on ASYNC
226 * IO must be woken up
229 static void n_tty_write_wakeup(struct tty_struct
*tty
)
231 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
232 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
235 static void n_tty_check_throttle(struct tty_struct
*tty
)
237 struct n_tty_data
*ldata
= tty
->disc_data
;
240 * Check the remaining room for the input canonicalization
241 * mode. We don't want to throttle the driver if we're in
242 * canonical mode and don't have a newline yet!
244 if (ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
)
249 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
250 if (N_TTY_BUF_SIZE
- read_cnt(ldata
) >= TTY_THRESHOLD_THROTTLE
)
252 throttled
= tty_throttle_safe(tty
);
256 __tty_set_flow_change(tty
, 0);
259 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
261 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
262 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
263 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
267 n_tty_kick_worker(tty
);
268 n_tty_write_wakeup(tty
->link
);
269 if (waitqueue_active(&tty
->link
->write_wait
))
270 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
274 /* If there is enough space in the read buffer now, let the
275 * low-level driver know. We use chars_in_buffer() to
276 * check the buffer, as it now knows about canonical mode.
277 * Otherwise, if the driver is throttled and the line is
278 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
279 * we won't get any more characters.
284 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
285 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
289 n_tty_kick_worker(tty
);
290 unthrottled
= tty_unthrottle_safe(tty
);
294 __tty_set_flow_change(tty
, 0);
298 * put_tty_queue - add character to tty
302 * Add a character to the tty read_buf queue.
304 * n_tty_receive_buf()/producer path:
305 * caller holds non-exclusive termios_rwsem
308 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
310 *read_buf_addr(ldata
, ldata
->read_head
) = c
;
315 * reset_buffer_flags - reset buffer state
316 * @tty: terminal to reset
318 * Reset the read buffer counters and clear the flags.
319 * Called from n_tty_open() and n_tty_flush_buffer().
321 * Locking: caller holds exclusive termios_rwsem
322 * (or locking is not required)
325 static void reset_buffer_flags(struct n_tty_data
*ldata
)
327 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
328 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
329 ldata
->commit_head
= 0;
330 ldata
->echo_mark
= 0;
331 ldata
->line_start
= 0;
334 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
338 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
342 if (tty
->link
->packet
) {
343 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
344 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
345 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
346 wake_up_interruptible(&tty
->link
->read_wait
);
351 * n_tty_flush_buffer - clean input queue
352 * @tty: terminal device
354 * Flush the input buffer. Called when the tty layer wants the
355 * buffer flushed (eg at hangup) or when the N_TTY line discipline
356 * internally has to clean the pending queue (for example some signals).
358 * Holds termios_rwsem to exclude producer/consumer while
359 * buffer indices are reset.
361 * Locking: ctrl_lock, exclusive termios_rwsem
364 static void n_tty_flush_buffer(struct tty_struct
*tty
)
366 down_write(&tty
->termios_rwsem
);
367 reset_buffer_flags(tty
->disc_data
);
368 n_tty_kick_worker(tty
);
371 n_tty_packet_mode_flush(tty
);
372 up_write(&tty
->termios_rwsem
);
376 * n_tty_chars_in_buffer - report available bytes
379 * Report the number of characters buffered to be delivered to user
380 * at this instant in time.
382 * Locking: exclusive termios_rwsem
385 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
389 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
391 down_write(&tty
->termios_rwsem
);
392 n
= chars_in_buffer(tty
);
393 up_write(&tty
->termios_rwsem
);
398 * is_utf8_continuation - utf8 multibyte check
401 * Returns true if the utf8 character 'c' is a multibyte continuation
402 * character. We use this to correctly compute the on screen size
403 * of the character when printing
406 static inline int is_utf8_continuation(unsigned char c
)
408 return (c
& 0xc0) == 0x80;
412 * is_continuation - multibyte check
415 * Returns true if the utf8 character 'c' is a multibyte continuation
416 * character and the terminal is in unicode mode.
419 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
421 return I_IUTF8(tty
) && is_utf8_continuation(c
);
425 * do_output_char - output one character
426 * @c: character (or partial unicode symbol)
427 * @tty: terminal device
428 * @space: space available in tty driver write buffer
430 * This is a helper function that handles one output character
431 * (including special characters like TAB, CR, LF, etc.),
432 * doing OPOST processing and putting the results in the
433 * tty driver's write buffer.
435 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
436 * and NLDLY. They simply aren't relevant in the world today.
437 * If you ever need them, add them here.
439 * Returns the number of bytes of buffer space used or -1 if
442 * Locking: should be called under the output_lock to protect
443 * the column state and space left in the buffer
446 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
448 struct n_tty_data
*ldata
= tty
->disc_data
;
461 ldata
->canon_column
= ldata
->column
= 0;
462 tty
->ops
->write(tty
, "\r\n", 2);
465 ldata
->canon_column
= ldata
->column
;
468 if (O_ONOCR(tty
) && ldata
->column
== 0)
473 ldata
->canon_column
= ldata
->column
= 0;
476 ldata
->canon_column
= ldata
->column
= 0;
479 spaces
= 8 - (ldata
->column
& 7);
480 if (O_TABDLY(tty
) == XTABS
) {
483 ldata
->column
+= spaces
;
484 tty
->ops
->write(tty
, " ", spaces
);
487 ldata
->column
+= spaces
;
490 if (ldata
->column
> 0)
497 if (!is_continuation(c
, tty
))
503 tty_put_char(tty
, c
);
508 * process_output - output post processor
509 * @c: character (or partial unicode symbol)
510 * @tty: terminal device
512 * Output one character with OPOST processing.
513 * Returns -1 when the output device is full and the character
516 * Locking: output_lock to protect column state and space left
517 * (also, this is called from n_tty_write under the
518 * tty layer write lock)
521 static int process_output(unsigned char c
, struct tty_struct
*tty
)
523 struct n_tty_data
*ldata
= tty
->disc_data
;
526 mutex_lock(&ldata
->output_lock
);
528 space
= tty_write_room(tty
);
529 retval
= do_output_char(c
, tty
, space
);
531 mutex_unlock(&ldata
->output_lock
);
539 * process_output_block - block post processor
540 * @tty: terminal device
541 * @buf: character buffer
542 * @nr: number of bytes to output
544 * Output a block of characters with OPOST processing.
545 * Returns the number of characters output.
547 * This path is used to speed up block console writes, among other
548 * things when processing blocks of output data. It handles only
549 * the simple cases normally found and helps to generate blocks of
550 * symbols for the console driver and thus improve performance.
552 * Locking: output_lock to protect column state and space left
553 * (also, this is called from n_tty_write under the
554 * tty layer write lock)
557 static ssize_t
process_output_block(struct tty_struct
*tty
,
558 const unsigned char *buf
, unsigned int nr
)
560 struct n_tty_data
*ldata
= tty
->disc_data
;
563 const unsigned char *cp
;
565 mutex_lock(&ldata
->output_lock
);
567 space
= tty_write_room(tty
);
569 mutex_unlock(&ldata
->output_lock
);
575 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
576 unsigned char c
= *cp
;
584 ldata
->canon_column
= ldata
->column
;
587 if (O_ONOCR(tty
) && ldata
->column
== 0)
591 ldata
->canon_column
= ldata
->column
= 0;
596 if (ldata
->column
> 0)
603 if (!is_continuation(c
, tty
))
610 i
= tty
->ops
->write(tty
, buf
, i
);
612 mutex_unlock(&ldata
->output_lock
);
617 * process_echoes - write pending echo characters
618 * @tty: terminal device
620 * Write previously buffered echo (and other ldisc-generated)
621 * characters to the tty.
623 * Characters generated by the ldisc (including echoes) need to
624 * be buffered because the driver's write buffer can fill during
625 * heavy program output. Echoing straight to the driver will
626 * often fail under these conditions, causing lost characters and
627 * resulting mismatches of ldisc state information.
629 * Since the ldisc state must represent the characters actually sent
630 * to the driver at the time of the write, operations like certain
631 * changes in column state are also saved in the buffer and executed
634 * A circular fifo buffer is used so that the most recent characters
635 * are prioritized. Also, when control characters are echoed with a
636 * prefixed "^", the pair is treated atomically and thus not separated.
638 * Locking: callers must hold output_lock
641 static size_t __process_echoes(struct tty_struct
*tty
)
643 struct n_tty_data
*ldata
= tty
->disc_data
;
644 int space
, old_space
;
648 old_space
= space
= tty_write_room(tty
);
650 tail
= ldata
->echo_tail
;
651 while (ldata
->echo_commit
!= tail
) {
652 c
= echo_buf(ldata
, tail
);
653 if (c
== ECHO_OP_START
) {
655 int no_space_left
= 0;
658 * If the buffer byte is the start of a multi-byte
659 * operation, get the next byte, which is either the
660 * op code or a control character value.
662 op
= echo_buf(ldata
, tail
+ 1);
665 unsigned int num_chars
, num_bs
;
667 case ECHO_OP_ERASE_TAB
:
668 num_chars
= echo_buf(ldata
, tail
+ 2);
671 * Determine how many columns to go back
672 * in order to erase the tab.
673 * This depends on the number of columns
674 * used by other characters within the tab
675 * area. If this (modulo 8) count is from
676 * the start of input rather than from a
677 * previous tab, we offset by canon column.
678 * Otherwise, tab spacing is normal.
680 if (!(num_chars
& 0x80))
681 num_chars
+= ldata
->canon_column
;
682 num_bs
= 8 - (num_chars
& 7);
684 if (num_bs
> space
) {
690 tty_put_char(tty
, '\b');
691 if (ldata
->column
> 0)
697 case ECHO_OP_SET_CANON_COL
:
698 ldata
->canon_column
= ldata
->column
;
702 case ECHO_OP_MOVE_BACK_COL
:
703 if (ldata
->column
> 0)
709 /* This is an escaped echo op start code */
714 tty_put_char(tty
, ECHO_OP_START
);
722 * If the op is not a special byte code,
723 * it is a ctrl char tagged to be echoed
724 * as "^X" (where X is the letter
725 * representing the control char).
726 * Note that we must ensure there is
727 * enough space for the whole ctrl pair.
734 tty_put_char(tty
, '^');
735 tty_put_char(tty
, op
^ 0100);
745 int retval
= do_output_char(c
, tty
, space
);
752 tty_put_char(tty
, c
);
759 /* If the echo buffer is nearly full (so that the possibility exists
760 * of echo overrun before the next commit), then discard enough
761 * data at the tail to prevent a subsequent overrun */
762 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
763 if (echo_buf(ldata
, tail
) == ECHO_OP_START
) {
764 if (echo_buf(ldata
, tail
+ 1) == ECHO_OP_ERASE_TAB
)
772 ldata
->echo_tail
= tail
;
773 return old_space
- space
;
776 static void commit_echoes(struct tty_struct
*tty
)
778 struct n_tty_data
*ldata
= tty
->disc_data
;
779 size_t nr
, old
, echoed
;
782 head
= ldata
->echo_head
;
783 ldata
->echo_mark
= head
;
784 old
= ldata
->echo_commit
- ldata
->echo_tail
;
786 /* Process committed echoes if the accumulated # of bytes
787 * is over the threshold (and try again each time another
788 * block is accumulated) */
789 nr
= head
- ldata
->echo_tail
;
790 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
793 mutex_lock(&ldata
->output_lock
);
794 ldata
->echo_commit
= head
;
795 echoed
= __process_echoes(tty
);
796 mutex_unlock(&ldata
->output_lock
);
798 if (echoed
&& tty
->ops
->flush_chars
)
799 tty
->ops
->flush_chars(tty
);
802 static void process_echoes(struct tty_struct
*tty
)
804 struct n_tty_data
*ldata
= tty
->disc_data
;
807 if (ldata
->echo_mark
== ldata
->echo_tail
)
810 mutex_lock(&ldata
->output_lock
);
811 ldata
->echo_commit
= ldata
->echo_mark
;
812 echoed
= __process_echoes(tty
);
813 mutex_unlock(&ldata
->output_lock
);
815 if (echoed
&& tty
->ops
->flush_chars
)
816 tty
->ops
->flush_chars(tty
);
819 /* NB: echo_mark and echo_head should be equivalent here */
820 static void flush_echoes(struct tty_struct
*tty
)
822 struct n_tty_data
*ldata
= tty
->disc_data
;
824 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
825 ldata
->echo_commit
== ldata
->echo_head
)
828 mutex_lock(&ldata
->output_lock
);
829 ldata
->echo_commit
= ldata
->echo_head
;
830 __process_echoes(tty
);
831 mutex_unlock(&ldata
->output_lock
);
835 * add_echo_byte - add a byte to the echo buffer
836 * @c: unicode byte to echo
839 * Add a character or operation byte to the echo buffer.
842 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
844 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
848 * echo_move_back_col - add operation to move back a column
851 * Add an operation to the echo buffer to move back one column.
854 static void echo_move_back_col(struct n_tty_data
*ldata
)
856 add_echo_byte(ECHO_OP_START
, ldata
);
857 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
861 * echo_set_canon_col - add operation to set the canon column
864 * Add an operation to the echo buffer to set the canon column
865 * to the current column.
868 static void echo_set_canon_col(struct n_tty_data
*ldata
)
870 add_echo_byte(ECHO_OP_START
, ldata
);
871 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
875 * echo_erase_tab - add operation to erase a tab
876 * @num_chars: number of character columns already used
877 * @after_tab: true if num_chars starts after a previous tab
880 * Add an operation to the echo buffer to erase a tab.
882 * Called by the eraser function, which knows how many character
883 * columns have been used since either a previous tab or the start
884 * of input. This information will be used later, along with
885 * canon column (if applicable), to go back the correct number
889 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
890 struct n_tty_data
*ldata
)
892 add_echo_byte(ECHO_OP_START
, ldata
);
893 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
895 /* We only need to know this modulo 8 (tab spacing) */
898 /* Set the high bit as a flag if num_chars is after a previous tab */
902 add_echo_byte(num_chars
, ldata
);
906 * echo_char_raw - echo a character raw
907 * @c: unicode byte to echo
908 * @tty: terminal device
910 * Echo user input back onto the screen. This must be called only when
911 * L_ECHO(tty) is true. Called from the driver receive_buf path.
913 * This variant does not treat control characters specially.
916 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
918 if (c
== ECHO_OP_START
) {
919 add_echo_byte(ECHO_OP_START
, ldata
);
920 add_echo_byte(ECHO_OP_START
, ldata
);
922 add_echo_byte(c
, ldata
);
927 * echo_char - echo a character
928 * @c: unicode byte to echo
929 * @tty: terminal device
931 * Echo user input back onto the screen. This must be called only when
932 * L_ECHO(tty) is true. Called from the driver receive_buf path.
934 * This variant tags control characters to be echoed as "^X"
935 * (where X is the letter representing the control char).
938 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
940 struct n_tty_data
*ldata
= tty
->disc_data
;
942 if (c
== ECHO_OP_START
) {
943 add_echo_byte(ECHO_OP_START
, ldata
);
944 add_echo_byte(ECHO_OP_START
, ldata
);
946 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
947 add_echo_byte(ECHO_OP_START
, ldata
);
948 add_echo_byte(c
, ldata
);
953 * finish_erasing - complete erase
957 static inline void finish_erasing(struct n_tty_data
*ldata
)
959 if (ldata
->erasing
) {
960 echo_char_raw('/', ldata
);
966 * eraser - handle erase function
967 * @c: character input
968 * @tty: terminal device
970 * Perform erase and necessary output when an erase character is
971 * present in the stream from the driver layer. Handles the complexities
972 * of UTF-8 multibyte symbols.
974 * n_tty_receive_buf()/producer path:
975 * caller holds non-exclusive termios_rwsem
978 static void eraser(unsigned char c
, struct tty_struct
*tty
)
980 struct n_tty_data
*ldata
= tty
->disc_data
;
981 enum { ERASE
, WERASE
, KILL
} kill_type
;
986 if (ldata
->read_head
== ldata
->canon_head
) {
987 /* process_output('\a', tty); */ /* what do you think? */
990 if (c
== ERASE_CHAR(tty
))
992 else if (c
== WERASE_CHAR(tty
))
996 ldata
->read_head
= ldata
->canon_head
;
999 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1000 ldata
->read_head
= ldata
->canon_head
;
1001 finish_erasing(ldata
);
1002 echo_char(KILL_CHAR(tty
), tty
);
1003 /* Add a newline if ECHOK is on and ECHOKE is off. */
1005 echo_char_raw('\n', ldata
);
1012 while (ldata
->read_head
!= ldata
->canon_head
) {
1013 head
= ldata
->read_head
;
1015 /* erase a single possibly multibyte character */
1018 c
= read_buf(ldata
, head
);
1019 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1021 /* do not partially erase */
1022 if (is_continuation(c
, tty
))
1025 if (kill_type
== WERASE
) {
1026 /* Equivalent to BSD's ALTWERASE. */
1027 if (isalnum(c
) || c
== '_')
1029 else if (seen_alnums
)
1032 cnt
= ldata
->read_head
- head
;
1033 ldata
->read_head
= head
;
1035 if (L_ECHOPRT(tty
)) {
1036 if (!ldata
->erasing
) {
1037 echo_char_raw('\\', ldata
);
1040 /* if cnt > 1, output a multi-byte character */
1044 echo_char_raw(read_buf(ldata
, head
), ldata
);
1045 echo_move_back_col(ldata
);
1047 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1048 echo_char(ERASE_CHAR(tty
), tty
);
1049 } else if (c
== '\t') {
1050 unsigned int num_chars
= 0;
1052 size_t tail
= ldata
->read_head
;
1055 * Count the columns used for characters
1056 * since the start of input or after a
1058 * This info is used to go back the correct
1059 * number of columns.
1061 while (tail
!= ldata
->canon_head
) {
1063 c
= read_buf(ldata
, tail
);
1067 } else if (iscntrl(c
)) {
1070 } else if (!is_continuation(c
, tty
)) {
1074 echo_erase_tab(num_chars
, after_tab
, ldata
);
1076 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1077 echo_char_raw('\b', ldata
);
1078 echo_char_raw(' ', ldata
);
1079 echo_char_raw('\b', ldata
);
1081 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1082 echo_char_raw('\b', ldata
);
1083 echo_char_raw(' ', ldata
);
1084 echo_char_raw('\b', ldata
);
1088 if (kill_type
== ERASE
)
1091 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1092 finish_erasing(ldata
);
1096 * isig - handle the ISIG optio
1100 * Called when a signal is being sent due to terminal input.
1101 * Called from the driver receive_buf path so serialized.
1103 * Performs input and output flush if !NOFLSH. In this context, the echo
1104 * buffer is 'output'. The signal is processed first to alert any current
1105 * readers or writers to discontinue and exit their i/o loops.
1107 * Locking: ctrl_lock
1110 static void __isig(int sig
, struct tty_struct
*tty
)
1112 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1114 kill_pgrp(tty_pgrp
, sig
, 1);
1119 static void isig(int sig
, struct tty_struct
*tty
)
1121 struct n_tty_data
*ldata
= tty
->disc_data
;
1123 if (L_NOFLSH(tty
)) {
1127 } else { /* signal and flush */
1128 up_read(&tty
->termios_rwsem
);
1129 down_write(&tty
->termios_rwsem
);
1133 /* clear echo buffer */
1134 mutex_lock(&ldata
->output_lock
);
1135 ldata
->echo_head
= ldata
->echo_tail
= 0;
1136 ldata
->echo_mark
= ldata
->echo_commit
= 0;
1137 mutex_unlock(&ldata
->output_lock
);
1139 /* clear output buffer */
1140 tty_driver_flush_buffer(tty
);
1142 /* clear input buffer */
1143 reset_buffer_flags(tty
->disc_data
);
1145 /* notify pty master of flush */
1147 n_tty_packet_mode_flush(tty
);
1149 up_write(&tty
->termios_rwsem
);
1150 down_read(&tty
->termios_rwsem
);
1155 * n_tty_receive_break - handle break
1158 * An RS232 break event has been hit in the incoming bitstream. This
1159 * can cause a variety of events depending upon the termios settings.
1161 * n_tty_receive_buf()/producer path:
1162 * caller holds non-exclusive termios_rwsem
1164 * Note: may get exclusive termios_rwsem if flushing input buffer
1167 static void n_tty_receive_break(struct tty_struct
*tty
)
1169 struct n_tty_data
*ldata
= tty
->disc_data
;
1173 if (I_BRKINT(tty
)) {
1177 if (I_PARMRK(tty
)) {
1178 put_tty_queue('\377', ldata
);
1179 put_tty_queue('\0', ldata
);
1181 put_tty_queue('\0', ldata
);
1182 if (waitqueue_active(&tty
->read_wait
))
1183 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1187 * n_tty_receive_overrun - handle overrun reporting
1190 * Data arrived faster than we could process it. While the tty
1191 * driver has flagged this the bits that were missed are gone
1194 * Called from the receive_buf path so single threaded. Does not
1195 * need locking as num_overrun and overrun_time are function
1199 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1201 struct n_tty_data
*ldata
= tty
->disc_data
;
1204 ldata
->num_overrun
++;
1205 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1206 time_after(ldata
->overrun_time
, jiffies
)) {
1207 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1209 ldata
->num_overrun
);
1210 ldata
->overrun_time
= jiffies
;
1211 ldata
->num_overrun
= 0;
1216 * n_tty_receive_parity_error - error notifier
1217 * @tty: terminal device
1220 * Process a parity error and queue the right data to indicate
1221 * the error case if necessary.
1223 * n_tty_receive_buf()/producer path:
1224 * caller holds non-exclusive termios_rwsem
1226 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1228 struct n_tty_data
*ldata
= tty
->disc_data
;
1233 if (I_PARMRK(tty
)) {
1234 put_tty_queue('\377', ldata
);
1235 put_tty_queue('\0', ldata
);
1236 put_tty_queue(c
, ldata
);
1238 put_tty_queue('\0', ldata
);
1240 put_tty_queue(c
, ldata
);
1241 if (waitqueue_active(&tty
->read_wait
))
1242 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1246 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1255 process_echoes(tty
);
1260 * n_tty_receive_char - perform processing
1261 * @tty: terminal device
1264 * Process an individual character of input received from the driver.
1265 * This is serialized with respect to itself by the rules for the
1268 * n_tty_receive_buf()/producer path:
1269 * caller holds non-exclusive termios_rwsem
1270 * publishes canon_head if canonical mode is active
1272 * Returns 1 if LNEXT was received, else returns 0
1276 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1278 struct n_tty_data
*ldata
= tty
->disc_data
;
1281 if (c
== START_CHAR(tty
)) {
1283 process_echoes(tty
);
1286 if (c
== STOP_CHAR(tty
)) {
1293 if (c
== INTR_CHAR(tty
)) {
1294 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1296 } else if (c
== QUIT_CHAR(tty
)) {
1297 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1299 } else if (c
== SUSP_CHAR(tty
)) {
1300 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1305 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1307 process_echoes(tty
);
1315 } else if (c
== '\n' && I_INLCR(tty
))
1318 if (ldata
->icanon
) {
1319 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1320 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1325 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1328 finish_erasing(ldata
);
1329 if (L_ECHOCTL(tty
)) {
1330 echo_char_raw('^', ldata
);
1331 echo_char_raw('\b', ldata
);
1337 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1338 size_t tail
= ldata
->canon_head
;
1340 finish_erasing(ldata
);
1342 echo_char_raw('\n', ldata
);
1343 while (tail
!= ldata
->read_head
) {
1344 echo_char(read_buf(ldata
, tail
), tty
);
1351 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1352 echo_char_raw('\n', ldata
);
1355 goto handle_newline
;
1357 if (c
== EOF_CHAR(tty
)) {
1358 c
= __DISABLED_CHAR
;
1359 goto handle_newline
;
1361 if ((c
== EOL_CHAR(tty
)) ||
1362 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1364 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1367 /* Record the column of first canon char. */
1368 if (ldata
->canon_head
== ldata
->read_head
)
1369 echo_set_canon_col(ldata
);
1374 * XXX does PARMRK doubling happen for
1375 * EOL_CHAR and EOL2_CHAR?
1377 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1378 put_tty_queue(c
, ldata
);
1381 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1382 put_tty_queue(c
, ldata
);
1383 smp_store_release(&ldata
->canon_head
, ldata
->read_head
);
1384 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1385 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1391 finish_erasing(ldata
);
1393 echo_char_raw('\n', ldata
);
1395 /* Record the column of first canon char. */
1396 if (ldata
->canon_head
== ldata
->read_head
)
1397 echo_set_canon_col(ldata
);
1403 /* PARMRK doubling check */
1404 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1405 put_tty_queue(c
, ldata
);
1407 put_tty_queue(c
, ldata
);
1412 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1414 struct n_tty_data
*ldata
= tty
->disc_data
;
1416 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1418 process_echoes(tty
);
1421 finish_erasing(ldata
);
1422 /* Record the column of first canon char. */
1423 if (ldata
->canon_head
== ldata
->read_head
)
1424 echo_set_canon_col(ldata
);
1428 /* PARMRK doubling check */
1429 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1430 put_tty_queue(c
, ldata
);
1431 put_tty_queue(c
, ldata
);
1434 static void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1436 n_tty_receive_char_inline(tty
, c
);
1440 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1442 struct n_tty_data
*ldata
= tty
->disc_data
;
1444 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1446 process_echoes(tty
);
1449 finish_erasing(ldata
);
1450 /* Record the column of first canon char. */
1451 if (ldata
->canon_head
== ldata
->read_head
)
1452 echo_set_canon_col(ldata
);
1456 put_tty_queue(c
, ldata
);
1459 static void n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1463 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1467 if (c
== STOP_CHAR(tty
))
1469 else if (c
== START_CHAR(tty
) ||
1470 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1471 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1472 c
!= SUSP_CHAR(tty
))) {
1474 process_echoes(tty
);
1480 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1486 n_tty_receive_break(tty
);
1490 n_tty_receive_parity_error(tty
, c
);
1493 n_tty_receive_overrun(tty
);
1496 printk(KERN_ERR
"%s: unknown flag %d\n",
1497 tty_name(tty
, buf
), flag
);
1503 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1505 struct n_tty_data
*ldata
= tty
->disc_data
;
1508 if (likely(flag
== TTY_NORMAL
)) {
1511 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1513 n_tty_receive_char(tty
, c
);
1515 n_tty_receive_char_flagged(tty
, c
, flag
);
1519 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1520 char *fp
, int count
)
1522 struct n_tty_data
*ldata
= tty
->disc_data
;
1525 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1526 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1527 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1528 ldata
->read_head
+= n
;
1532 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1533 n
= min_t(size_t, count
, N_TTY_BUF_SIZE
- head
);
1534 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1535 ldata
->read_head
+= n
;
1539 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1540 char *fp
, int count
)
1542 struct n_tty_data
*ldata
= tty
->disc_data
;
1543 char flag
= TTY_NORMAL
;
1548 if (likely(flag
== TTY_NORMAL
))
1549 put_tty_queue(*cp
++, ldata
);
1551 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1556 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1557 char *fp
, int count
)
1559 char flag
= TTY_NORMAL
;
1564 if (likely(flag
== TTY_NORMAL
))
1565 n_tty_receive_char_closing(tty
, *cp
++);
1567 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1572 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1573 char *fp
, int count
)
1575 struct n_tty_data
*ldata
= tty
->disc_data
;
1576 char flag
= TTY_NORMAL
;
1581 if (likely(flag
== TTY_NORMAL
)) {
1582 unsigned char c
= *cp
++;
1586 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1588 if (L_EXTPROC(tty
)) {
1589 put_tty_queue(c
, ldata
);
1592 if (!test_bit(c
, ldata
->char_map
))
1593 n_tty_receive_char_inline(tty
, c
);
1594 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1597 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1601 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1606 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1607 char *fp
, int count
)
1609 struct n_tty_data
*ldata
= tty
->disc_data
;
1610 char flag
= TTY_NORMAL
;
1615 if (likely(flag
== TTY_NORMAL
)) {
1616 unsigned char c
= *cp
++;
1618 if (!test_bit(c
, ldata
->char_map
))
1619 n_tty_receive_char_fast(tty
, c
);
1620 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1623 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1627 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1631 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1632 char *fp
, int count
)
1634 struct n_tty_data
*ldata
= tty
->disc_data
;
1635 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1637 if (ldata
->real_raw
)
1638 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1639 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1640 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1641 else if (tty
->closing
&& !L_EXTPROC(tty
))
1642 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1645 char flag
= TTY_NORMAL
;
1649 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1653 if (!preops
&& !I_PARMRK(tty
))
1654 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1656 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1659 if (tty
->ops
->flush_chars
)
1660 tty
->ops
->flush_chars(tty
);
1663 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1666 /* publish read_head to consumer */
1667 smp_store_release(&ldata
->commit_head
, ldata
->read_head
);
1669 if ((read_cnt(ldata
) >= ldata
->minimum_to_wake
) || L_EXTPROC(tty
)) {
1670 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1671 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1676 * n_tty_receive_buf_common - process input
1677 * @tty: device to receive input
1679 * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
1680 * @count: number of input chars in @cp
1682 * Called by the terminal driver when a block of characters has
1683 * been received. This function must be called from soft contexts
1684 * not from interrupt context. The driver is responsible for making
1685 * calls one at a time and in order (or using flush_to_ldisc)
1687 * Returns the # of input chars from @cp which were processed.
1689 * In canonical mode, the maximum line length is 4096 chars (including
1690 * the line termination char); lines longer than 4096 chars are
1691 * truncated. After 4095 chars, input data is still processed but
1692 * not stored. Overflow processing ensures the tty can always
1693 * receive more input until at least one line can be read.
1695 * In non-canonical mode, the read buffer will only accept 4095 chars;
1696 * this provides the necessary space for a newline char if the input
1697 * mode is switched to canonical.
1699 * Note it is possible for the read buffer to _contain_ 4096 chars
1700 * in non-canonical mode: the read buffer could already contain the
1701 * maximum canon line of 4096 chars when the mode is switched to
1704 * n_tty_receive_buf()/producer path:
1705 * claims non-exclusive termios_rwsem
1706 * publishes commit_head or canon_head
1709 n_tty_receive_buf_common(struct tty_struct
*tty
, const unsigned char *cp
,
1710 char *fp
, int count
, int flow
)
1712 struct n_tty_data
*ldata
= tty
->disc_data
;
1713 int room
, n
, rcvd
= 0, overflow
;
1715 down_read(&tty
->termios_rwsem
);
1719 * When PARMRK is set, each input char may take up to 3 chars
1720 * in the read buf; reduce the buffer space avail by 3x
1722 * If we are doing input canonicalization, and there are no
1723 * pending newlines, let characters through without limit, so
1724 * that erase characters will be handled. Other excess
1725 * characters will be beeped.
1727 * paired with store in *_copy_from_read_buf() -- guarantees
1728 * the consumer has loaded the data in read_buf up to the new
1729 * read_tail (so this producer will not overwrite unread data)
1731 size_t tail
= smp_load_acquire(&ldata
->read_tail
);
1733 room
= N_TTY_BUF_SIZE
- (ldata
->read_head
- tail
);
1735 room
= (room
+ 2) / 3;
1738 overflow
= ldata
->icanon
&& ldata
->canon_head
== tail
;
1739 if (overflow
&& room
< 0)
1742 ldata
->no_room
= flow
&& !room
;
1746 n
= min(count
, room
);
1750 /* ignore parity errors if handling overflow */
1751 if (!overflow
|| !fp
|| *fp
!= TTY_PARITY
)
1752 __receive_buf(tty
, cp
, fp
, n
);
1761 tty
->receive_room
= room
;
1763 /* Unthrottle if handling overflow on pty */
1764 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
) {
1766 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
1767 tty_unthrottle_safe(tty
);
1768 __tty_set_flow_change(tty
, 0);
1771 n_tty_check_throttle(tty
);
1773 up_read(&tty
->termios_rwsem
);
1778 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1779 char *fp
, int count
)
1781 n_tty_receive_buf_common(tty
, cp
, fp
, count
, 0);
1784 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1785 char *fp
, int count
)
1787 return n_tty_receive_buf_common(tty
, cp
, fp
, count
, 1);
1790 int is_ignored(int sig
)
1792 return (sigismember(¤t
->blocked
, sig
) ||
1793 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1797 * n_tty_set_termios - termios data changed
1799 * @old: previous data
1801 * Called by the tty layer when the user changes termios flags so
1802 * that the line discipline can plan ahead. This function cannot sleep
1803 * and is protected from re-entry by the tty layer. The user is
1804 * guaranteed that this function will not be re-entered or in progress
1805 * when the ldisc is closed.
1807 * Locking: Caller holds tty->termios_rwsem
1810 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1812 struct n_tty_data
*ldata
= tty
->disc_data
;
1814 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1815 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1816 ldata
->line_start
= ldata
->read_tail
;
1817 if (!L_ICANON(tty
) || !read_cnt(ldata
)) {
1818 ldata
->canon_head
= ldata
->read_tail
;
1821 set_bit((ldata
->read_head
- 1) & (N_TTY_BUF_SIZE
- 1),
1823 ldata
->canon_head
= ldata
->read_head
;
1826 ldata
->commit_head
= ldata
->read_head
;
1831 ldata
->icanon
= (L_ICANON(tty
) != 0);
1833 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1834 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1835 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1837 bitmap_zero(ldata
->char_map
, 256);
1839 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1840 set_bit('\r', ldata
->char_map
);
1842 set_bit('\n', ldata
->char_map
);
1844 if (L_ICANON(tty
)) {
1845 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1846 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1847 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1848 set_bit('\n', ldata
->char_map
);
1849 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1850 if (L_IEXTEN(tty
)) {
1851 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1852 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1853 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1855 set_bit(REPRINT_CHAR(tty
),
1860 set_bit(START_CHAR(tty
), ldata
->char_map
);
1861 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1864 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1865 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1866 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1868 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1870 ldata
->real_raw
= 0;
1873 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1874 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1875 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1876 ldata
->real_raw
= 1;
1878 ldata
->real_raw
= 0;
1881 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1882 * been stopped by STOP_CHAR(tty) before it.
1884 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1886 process_echoes(tty
);
1889 /* The termios change make the tty ready for I/O */
1890 wake_up_interruptible(&tty
->write_wait
);
1891 wake_up_interruptible(&tty
->read_wait
);
1895 * n_tty_close - close the ldisc for this tty
1898 * Called from the terminal layer when this line discipline is
1899 * being shut down, either because of a close or becsuse of a
1900 * discipline change. The function will not be called while other
1901 * ldisc methods are in progress.
1904 static void n_tty_close(struct tty_struct
*tty
)
1906 struct n_tty_data
*ldata
= tty
->disc_data
;
1909 n_tty_packet_mode_flush(tty
);
1912 tty
->disc_data
= NULL
;
1916 * n_tty_open - open an ldisc
1917 * @tty: terminal to open
1919 * Called when this line discipline is being attached to the
1920 * terminal device. Can sleep. Called serialized so that no
1921 * other events will occur in parallel. No further open will occur
1925 static int n_tty_open(struct tty_struct
*tty
)
1927 struct n_tty_data
*ldata
;
1929 /* Currently a malloc failure here can panic */
1930 ldata
= vmalloc(sizeof(*ldata
));
1934 ldata
->overrun_time
= jiffies
;
1935 mutex_init(&ldata
->atomic_read_lock
);
1936 mutex_init(&ldata
->output_lock
);
1938 tty
->disc_data
= ldata
;
1939 reset_buffer_flags(tty
->disc_data
);
1941 ldata
->canon_column
= 0;
1942 ldata
->minimum_to_wake
= 1;
1943 ldata
->num_overrun
= 0;
1947 /* indicate buffer work may resume */
1948 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1949 n_tty_set_termios(tty
, NULL
);
1950 tty_unthrottle(tty
);
1957 static inline int input_available_p(struct tty_struct
*tty
, int poll
)
1959 struct n_tty_data
*ldata
= tty
->disc_data
;
1960 int amt
= poll
&& !TIME_CHAR(tty
) && MIN_CHAR(tty
) ? MIN_CHAR(tty
) : 1;
1962 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1963 return ldata
->canon_head
!= ldata
->read_tail
;
1965 return ldata
->commit_head
- ldata
->read_tail
>= amt
;
1968 static inline int check_other_done(struct tty_struct
*tty
)
1970 int done
= test_bit(TTY_OTHER_DONE
, &tty
->flags
);
1972 /* paired with cmpxchg() in check_other_closed(); ensures
1973 * read buffer head index is not stale
1975 smp_mb__after_atomic();
1981 * copy_from_read_buf - copy read data directly
1982 * @tty: terminal device
1986 * Helper function to speed up n_tty_read. It is only called when
1987 * ICANON is off; it copies characters straight from the tty queue to
1988 * user space directly. It can be profitably called twice; once to
1989 * drain the space from the tail pointer to the (physical) end of the
1990 * buffer, and once to drain the space from the (physical) beginning of
1991 * the buffer to head pointer.
1993 * Called under the ldata->atomic_read_lock sem
1995 * n_tty_read()/consumer path:
1996 * caller holds non-exclusive termios_rwsem
1997 * read_tail published
2000 static int copy_from_read_buf(struct tty_struct
*tty
,
2001 unsigned char __user
**b
,
2005 struct n_tty_data
*ldata
= tty
->disc_data
;
2009 size_t head
= smp_load_acquire(&ldata
->commit_head
);
2010 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2013 n
= min(head
- ldata
->read_tail
, N_TTY_BUF_SIZE
- tail
);
2016 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2018 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
2019 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
2021 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ n
);
2022 /* Turn single EOF into zero-length read */
2023 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&&
2024 (head
== ldata
->read_tail
))
2033 * canon_copy_from_read_buf - copy read data in canonical mode
2034 * @tty: terminal device
2038 * Helper function for n_tty_read. It is only called when ICANON is on;
2039 * it copies one line of input up to and including the line-delimiting
2040 * character into the user-space buffer.
2042 * NB: When termios is changed from non-canonical to canonical mode and
2043 * the read buffer contains data, n_tty_set_termios() simulates an EOF
2044 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
2045 * This causes data already processed as input to be immediately available
2046 * as input although a newline has not been received.
2048 * Called under the atomic_read_lock mutex
2050 * n_tty_read()/consumer path:
2051 * caller holds non-exclusive termios_rwsem
2052 * read_tail published
2055 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
2056 unsigned char __user
**b
,
2059 struct n_tty_data
*ldata
= tty
->disc_data
;
2060 size_t n
, size
, more
, c
;
2066 /* N.B. avoid overrun if nr == 0 */
2067 n
= min(*nr
, smp_load_acquire(&ldata
->canon_head
) - ldata
->read_tail
);
2071 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2072 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
2074 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2075 __func__
, *nr
, tail
, n
, size
);
2077 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
2078 more
= n
- (size
- tail
);
2079 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2080 /* scan wrapped without finding set bit */
2081 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2084 } else if (eol
!= size
)
2087 size
= N_TTY_BUF_SIZE
- tail
;
2089 if (n
> N_TTY_BUF_SIZE
)
2090 n
+= N_TTY_BUF_SIZE
;
2094 if (found
&& !ldata
->push
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
2096 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
2099 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2100 __func__
, eol
, found
, n
, c
, size
, more
);
2103 ret
= tty_copy_to_user(tty
, *b
, read_buf_addr(ldata
, tail
), size
);
2106 ret
= tty_copy_to_user(tty
, *b
+ size
, ldata
->read_buf
, n
- size
);
2108 ret
= tty_copy_to_user(tty
, *b
, read_buf_addr(ldata
, tail
), n
);
2116 clear_bit(eol
, ldata
->read_flags
);
2117 smp_store_release(&ldata
->read_tail
, ldata
->read_tail
+ c
);
2121 ldata
->line_start
= ldata
->read_tail
;
2124 tty_audit_push(tty
);
2126 return eof_push
? -EAGAIN
: 0;
2129 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2133 * job_control - check job control
2135 * @file: file handle
2137 * Perform job control management checks on this file/tty descriptor
2138 * and if appropriate send any needed signals and return a negative
2139 * error code if action should be taken.
2141 * Locking: redirected write test is safe
2142 * current->signal->tty check is safe
2143 * ctrl_lock to safely reference tty->pgrp
2146 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2148 /* Job control check -- must be done at start and after
2149 every sleep (POSIX.1 7.1.1.4). */
2150 /* NOTE: not yet done after every sleep pending a thorough
2151 check of the logic of this change. -- jlc */
2152 /* don't stop on /dev/console */
2153 if (file
->f_op
->write
== redirected_tty_write
||
2154 current
->signal
->tty
!= tty
)
2157 spin_lock_irq(&tty
->ctrl_lock
);
2159 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2160 else if (task_pgrp(current
) != tty
->pgrp
) {
2161 spin_unlock_irq(&tty
->ctrl_lock
);
2162 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
2164 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
2165 set_thread_flag(TIF_SIGPENDING
);
2166 return -ERESTARTSYS
;
2168 spin_unlock_irq(&tty
->ctrl_lock
);
2174 * n_tty_read - read function for tty
2176 * @file: file object
2177 * @buf: userspace buffer pointer
2180 * Perform reads for the line discipline. We are guaranteed that the
2181 * line discipline will not be closed under us but we may get multiple
2182 * parallel readers and must handle this ourselves. We may also get
2183 * a hangup. Always called in user context, may sleep.
2185 * This code must be sure never to sleep through a hangup.
2187 * n_tty_read()/consumer path:
2188 * claims non-exclusive termios_rwsem
2189 * publishes read_tail
2192 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2193 unsigned char __user
*buf
, size_t nr
)
2195 struct n_tty_data
*ldata
= tty
->disc_data
;
2196 unsigned char __user
*b
= buf
;
2197 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2205 c
= job_control(tty
, file
);
2210 * Internal serialization of reads.
2212 if (file
->f_flags
& O_NONBLOCK
) {
2213 if (!mutex_trylock(&ldata
->atomic_read_lock
))
2216 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
))
2217 return -ERESTARTSYS
;
2220 down_read(&tty
->termios_rwsem
);
2223 timeout
= MAX_SCHEDULE_TIMEOUT
;
2224 if (!ldata
->icanon
) {
2225 minimum
= MIN_CHAR(tty
);
2227 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2229 ldata
->minimum_to_wake
= 1;
2230 else if (!waitqueue_active(&tty
->read_wait
) ||
2231 (ldata
->minimum_to_wake
> minimum
))
2232 ldata
->minimum_to_wake
= minimum
;
2234 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2235 ldata
->minimum_to_wake
= minimum
= 1;
2239 packet
= tty
->packet
;
2240 tail
= ldata
->read_tail
;
2242 add_wait_queue(&tty
->read_wait
, &wait
);
2244 /* First test for status change. */
2245 if (packet
&& tty
->link
->ctrl_status
) {
2249 spin_lock_irq(&tty
->link
->ctrl_lock
);
2250 cs
= tty
->link
->ctrl_status
;
2251 tty
->link
->ctrl_status
= 0;
2252 spin_unlock_irq(&tty
->link
->ctrl_lock
);
2253 if (tty_put_user(tty
, cs
, b
++)) {
2262 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2263 ((minimum
- (b
- buf
)) >= 1))
2264 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2266 done
= check_other_done(tty
);
2268 if (!input_available_p(tty
, 0)) {
2273 if (tty_hung_up_p(file
))
2277 if (file
->f_flags
& O_NONBLOCK
) {
2281 if (signal_pending(current
)) {
2282 retval
= -ERESTARTSYS
;
2285 up_read(&tty
->termios_rwsem
);
2287 timeout
= wait_woken(&wait
, TASK_INTERRUPTIBLE
,
2290 down_read(&tty
->termios_rwsem
);
2294 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2295 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2296 if (retval
== -EAGAIN
) {
2304 /* Deal with packet mode. */
2305 if (packet
&& b
== buf
) {
2306 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2314 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2315 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2322 n_tty_check_unthrottle(tty
);
2324 if (b
- buf
>= minimum
)
2329 if (tail
!= ldata
->read_tail
)
2330 n_tty_kick_worker(tty
);
2331 up_read(&tty
->termios_rwsem
);
2333 remove_wait_queue(&tty
->read_wait
, &wait
);
2334 if (!waitqueue_active(&tty
->read_wait
))
2335 ldata
->minimum_to_wake
= minimum
;
2337 mutex_unlock(&ldata
->atomic_read_lock
);
2346 * n_tty_write - write function for tty
2348 * @file: file object
2349 * @buf: userspace buffer pointer
2352 * Write function of the terminal device. This is serialized with
2353 * respect to other write callers but not to termios changes, reads
2354 * and other such events. Since the receive code will echo characters,
2355 * thus calling driver write methods, the output_lock is used in
2356 * the output processing functions called here as well as in the
2357 * echo processing function to protect the column state and space
2358 * left in the buffer.
2360 * This code must be sure never to sleep through a hangup.
2362 * Locking: output_lock to protect column state and space left
2363 * (note that the process_output*() functions take this
2367 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2368 const unsigned char *buf
, size_t nr
)
2370 const unsigned char *b
= buf
;
2371 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2375 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2376 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2377 retval
= tty_check_change(tty
);
2382 down_read(&tty
->termios_rwsem
);
2384 /* Write out any echoed characters that are still pending */
2385 process_echoes(tty
);
2387 add_wait_queue(&tty
->write_wait
, &wait
);
2389 if (signal_pending(current
)) {
2390 retval
= -ERESTARTSYS
;
2393 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2399 ssize_t num
= process_output_block(tty
, b
, nr
);
2411 if (process_output(c
, tty
) < 0)
2415 if (tty
->ops
->flush_chars
)
2416 tty
->ops
->flush_chars(tty
);
2418 struct n_tty_data
*ldata
= tty
->disc_data
;
2421 mutex_lock(&ldata
->output_lock
);
2422 c
= tty
->ops
->write(tty
, b
, nr
);
2423 mutex_unlock(&ldata
->output_lock
);
2436 if (file
->f_flags
& O_NONBLOCK
) {
2440 up_read(&tty
->termios_rwsem
);
2442 wait_woken(&wait
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2444 down_read(&tty
->termios_rwsem
);
2447 remove_wait_queue(&tty
->write_wait
, &wait
);
2448 if (b
- buf
!= nr
&& tty
->fasync
)
2449 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2450 up_read(&tty
->termios_rwsem
);
2451 return (b
- buf
) ? b
- buf
: retval
;
2455 * n_tty_poll - poll method for N_TTY
2456 * @tty: terminal device
2457 * @file: file accessing it
2460 * Called when the line discipline is asked to poll() for data or
2461 * for special events. This code is not serialized with respect to
2462 * other events save open/close.
2464 * This code must be sure never to sleep through a hangup.
2465 * Called without the kernel lock held - fine
2468 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2471 struct n_tty_data
*ldata
= tty
->disc_data
;
2472 unsigned int mask
= 0;
2474 poll_wait(file
, &tty
->read_wait
, wait
);
2475 poll_wait(file
, &tty
->write_wait
, wait
);
2476 if (check_other_done(tty
))
2478 if (input_available_p(tty
, 1))
2479 mask
|= POLLIN
| POLLRDNORM
;
2480 if (tty
->packet
&& tty
->link
->ctrl_status
)
2481 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2482 if (tty_hung_up_p(file
))
2484 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2485 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2486 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2488 ldata
->minimum_to_wake
= 1;
2490 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2491 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2492 tty_write_room(tty
) > 0)
2493 mask
|= POLLOUT
| POLLWRNORM
;
2497 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2499 size_t nr
, head
, tail
;
2501 if (ldata
->canon_head
== ldata
->read_tail
)
2503 head
= ldata
->canon_head
;
2504 tail
= ldata
->read_tail
;
2506 /* Skip EOF-chars.. */
2507 while (head
!= tail
) {
2508 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2509 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2516 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2517 unsigned int cmd
, unsigned long arg
)
2519 struct n_tty_data
*ldata
= tty
->disc_data
;
2524 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2526 down_write(&tty
->termios_rwsem
);
2528 retval
= inq_canon(ldata
);
2530 retval
= read_cnt(ldata
);
2531 up_write(&tty
->termios_rwsem
);
2532 return put_user(retval
, (unsigned int __user
*) arg
);
2534 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2538 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2540 struct n_tty_data
*ldata
= tty
->disc_data
;
2542 if (!waitqueue_active(&tty
->read_wait
)) {
2544 ldata
->minimum_to_wake
= 1;
2545 else if (!tty
->fasync
)
2546 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2550 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2551 .magic
= TTY_LDISC_MAGIC
,
2554 .close
= n_tty_close
,
2555 .flush_buffer
= n_tty_flush_buffer
,
2556 .chars_in_buffer
= n_tty_chars_in_buffer
,
2558 .write
= n_tty_write
,
2559 .ioctl
= n_tty_ioctl
,
2560 .set_termios
= n_tty_set_termios
,
2562 .receive_buf
= n_tty_receive_buf
,
2563 .write_wakeup
= n_tty_write_wakeup
,
2564 .fasync
= n_tty_fasync
,
2565 .receive_buf2
= n_tty_receive_buf2
,
2569 * n_tty_inherit_ops - inherit N_TTY methods
2570 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2572 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2576 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2578 *ops
= tty_ldisc_N_TTY
;
2580 ops
->refcount
= ops
->flags
= 0;
2582 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);