2 * n_tty.c --- implements the N_TTY line discipline.
4 * This code used to be in tty_io.c, but things are getting hairy
5 * enough that it made sense to split things off. (The N_TTY
6 * processing has changed so much that it's hardly recognizable,
9 * Note that the open routine for N_TTY is guaranteed never to return
10 * an error. This is because Linux will fall back to setting a line
11 * to N_TTY if it can not switch to any other line discipline.
13 * Written by Theodore Ts'o, Copyright 1994.
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18 * This file may be redistributed under the terms of the GNU General Public
21 * Reduced memory usage for older ARM systems - Russell King.
23 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
24 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25 * who actually finally proved there really was a race.
27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29 * Also fixed a bug in BLOCKING mode where n_tty_write returns
33 #include <linux/types.h>
34 #include <linux/major.h>
35 #include <linux/errno.h>
36 #include <linux/signal.h>
37 #include <linux/fcntl.h>
38 #include <linux/sched.h>
39 #include <linux/interrupt.h>
40 #include <linux/tty.h>
41 #include <linux/timer.h>
42 #include <linux/ctype.h>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
48 #include <linux/audit.h>
49 #include <linux/file.h>
50 #include <linux/uaccess.h>
51 #include <linux/module.h>
52 #include <linux/ratelimit.h>
53 #include <linux/vmalloc.h>
56 /* number of characters left in xmit buffer before select has we have room */
57 #define WAKEUP_CHARS 256
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
64 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65 #define TTY_THRESHOLD_UNTHROTTLE 128
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
73 #define ECHO_OP_START 0xff
74 #define ECHO_OP_MOVE_BACK_COL 0x80
75 #define ECHO_OP_SET_CANON_COL 0x81
76 #define ECHO_OP_ERASE_TAB 0x82
78 #define ECHO_COMMIT_WATERMARK 256
79 #define ECHO_BLOCK 256
80 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
85 # define n_tty_trace(f, args...) trace_printk(f, ##args)
87 # define n_tty_trace(f, args...)
91 /* producer-published */
97 DECLARE_BITMAP(char_map
, 256);
99 /* private to n_tty_receive_overrun (single-threaded) */
100 unsigned long overrun_time
;
106 /* must hold exclusive termios_rwsem to reset these */
107 unsigned char lnext
:1, erasing
:1, raw
:1, real_raw
:1, icanon
:1;
108 unsigned char push
:1;
110 /* shared by producer and consumer */
111 char read_buf
[N_TTY_BUF_SIZE
];
112 DECLARE_BITMAP(read_flags
, N_TTY_BUF_SIZE
);
113 unsigned char echo_buf
[N_TTY_BUF_SIZE
];
117 /* consumer-published */
121 /* protected by output lock */
123 unsigned int canon_column
;
126 struct mutex atomic_read_lock
;
127 struct mutex output_lock
;
130 static inline size_t read_cnt(struct n_tty_data
*ldata
)
132 return ldata
->read_head
- ldata
->read_tail
;
135 static inline unsigned char read_buf(struct n_tty_data
*ldata
, size_t i
)
137 return ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
140 static inline unsigned char *read_buf_addr(struct n_tty_data
*ldata
, size_t i
)
142 return &ldata
->read_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
145 static inline unsigned char echo_buf(struct n_tty_data
*ldata
, size_t i
)
147 return ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
150 static inline unsigned char *echo_buf_addr(struct n_tty_data
*ldata
, size_t i
)
152 return &ldata
->echo_buf
[i
& (N_TTY_BUF_SIZE
- 1)];
155 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
156 unsigned char __user
*ptr
)
158 struct n_tty_data
*ldata
= tty
->disc_data
;
160 tty_audit_add_data(tty
, &x
, 1, ldata
->icanon
);
161 return put_user(x
, ptr
);
164 static int receive_room(struct tty_struct
*tty
)
166 struct n_tty_data
*ldata
= tty
->disc_data
;
170 /* Multiply read_cnt by 3, since each byte might take up to
171 * three times as many spaces when PARMRK is set (depending on
172 * its flags, e.g. parity error). */
173 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) * 3 - 1;
175 left
= N_TTY_BUF_SIZE
- read_cnt(ldata
) - 1;
178 * If we are doing input canonicalization, and there are no
179 * pending newlines, let characters through without limit, so
180 * that erase characters will be handled. Other excess
181 * characters will be beeped.
184 left
= ldata
->icanon
&& ldata
->canon_head
== ldata
->read_tail
;
190 * n_tty_set_room - receive space
193 * Re-schedules the flip buffer work if space just became available.
195 * Caller holds exclusive termios_rwsem
197 * n_tty_read()/consumer path:
198 * holds non-exclusive termios_rwsem
201 static void n_tty_set_room(struct tty_struct
*tty
)
203 struct n_tty_data
*ldata
= tty
->disc_data
;
205 /* Did this open up the receive buffer? We may need to flip */
206 if (unlikely(ldata
->no_room
) && receive_room(tty
)) {
209 WARN_RATELIMIT(tty
->port
->itty
== NULL
,
210 "scheduling with invalid itty\n");
211 /* see if ldisc has been killed - if so, this means that
212 * even though the ldisc has been halted and ->buf.work
213 * cancelled, ->buf.work is about to be rescheduled
215 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED
, &tty
->flags
),
216 "scheduling buffer work for halted ldisc\n");
217 queue_work(system_unbound_wq
, &tty
->port
->buf
.work
);
221 static ssize_t
chars_in_buffer(struct tty_struct
*tty
)
223 struct n_tty_data
*ldata
= tty
->disc_data
;
229 n
= ldata
->canon_head
- ldata
->read_tail
;
234 * n_tty_write_wakeup - asynchronous I/O notifier
237 * Required for the ptys, serial driver etc. since processes
238 * that attach themselves to the master and rely on ASYNC
239 * IO must be woken up
242 static void n_tty_write_wakeup(struct tty_struct
*tty
)
244 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
245 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
248 static void n_tty_check_throttle(struct tty_struct
*tty
)
250 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
)
253 * Check the remaining room for the input canonicalization
254 * mode. We don't want to throttle the driver if we're in
255 * canonical mode and don't have a newline yet!
259 tty_set_flow_change(tty
, TTY_THROTTLE_SAFE
);
260 if (receive_room(tty
) >= TTY_THRESHOLD_THROTTLE
)
262 throttled
= tty_throttle_safe(tty
);
266 __tty_set_flow_change(tty
, 0);
269 static void n_tty_check_unthrottle(struct tty_struct
*tty
)
271 if (tty
->driver
->type
== TTY_DRIVER_TYPE_PTY
&&
272 tty
->link
->ldisc
->ops
->write_wakeup
== n_tty_write_wakeup
) {
273 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
278 n_tty_write_wakeup(tty
->link
);
279 if (waitqueue_active(&tty
->link
->write_wait
))
280 wake_up_interruptible_poll(&tty
->link
->write_wait
, POLLOUT
);
284 /* If there is enough space in the read buffer now, let the
285 * low-level driver know. We use chars_in_buffer() to
286 * check the buffer, as it now knows about canonical mode.
287 * Otherwise, if the driver is throttled and the line is
288 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
289 * we won't get any more characters.
294 tty_set_flow_change(tty
, TTY_UNTHROTTLE_SAFE
);
295 if (chars_in_buffer(tty
) > TTY_THRESHOLD_UNTHROTTLE
)
300 unthrottled
= tty_unthrottle_safe(tty
);
304 __tty_set_flow_change(tty
, 0);
308 * put_tty_queue - add character to tty
312 * Add a character to the tty read_buf queue.
314 * n_tty_receive_buf()/producer path:
315 * caller holds non-exclusive termios_rwsem
318 * read_head is only considered 'published' if canonical mode is
322 static inline void put_tty_queue(unsigned char c
, struct n_tty_data
*ldata
)
324 *read_buf_addr(ldata
, ldata
->read_head
++) = c
;
328 * reset_buffer_flags - reset buffer state
329 * @tty: terminal to reset
331 * Reset the read buffer counters and clear the flags.
332 * Called from n_tty_open() and n_tty_flush_buffer().
334 * Locking: caller holds exclusive termios_rwsem
335 * (or locking is not required)
338 static void reset_buffer_flags(struct n_tty_data
*ldata
)
340 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
341 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
342 ldata
->echo_mark
= 0;
343 ldata
->line_start
= 0;
346 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
350 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
354 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
355 if (tty
->link
->packet
) {
356 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
357 if (waitqueue_active(&tty
->link
->read_wait
))
358 wake_up_interruptible(&tty
->link
->read_wait
);
360 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
364 * n_tty_flush_buffer - clean input queue
365 * @tty: terminal device
367 * Flush the input buffer. Called when the tty layer wants the
368 * buffer flushed (eg at hangup) or when the N_TTY line discipline
369 * internally has to clean the pending queue (for example some signals).
371 * Holds termios_rwsem to exclude producer/consumer while
372 * buffer indices are reset.
374 * Locking: ctrl_lock, exclusive termios_rwsem
377 static void n_tty_flush_buffer(struct tty_struct
*tty
)
379 down_write(&tty
->termios_rwsem
);
380 reset_buffer_flags(tty
->disc_data
);
384 n_tty_packet_mode_flush(tty
);
385 up_write(&tty
->termios_rwsem
);
389 * n_tty_chars_in_buffer - report available bytes
392 * Report the number of characters buffered to be delivered to user
393 * at this instant in time.
395 * Locking: exclusive termios_rwsem
398 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
402 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
404 down_write(&tty
->termios_rwsem
);
405 n
= chars_in_buffer(tty
);
406 up_write(&tty
->termios_rwsem
);
411 * is_utf8_continuation - utf8 multibyte check
414 * Returns true if the utf8 character 'c' is a multibyte continuation
415 * character. We use this to correctly compute the on screen size
416 * of the character when printing
419 static inline int is_utf8_continuation(unsigned char c
)
421 return (c
& 0xc0) == 0x80;
425 * is_continuation - multibyte check
428 * Returns true if the utf8 character 'c' is a multibyte continuation
429 * character and the terminal is in unicode mode.
432 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
434 return I_IUTF8(tty
) && is_utf8_continuation(c
);
438 * do_output_char - output one character
439 * @c: character (or partial unicode symbol)
440 * @tty: terminal device
441 * @space: space available in tty driver write buffer
443 * This is a helper function that handles one output character
444 * (including special characters like TAB, CR, LF, etc.),
445 * doing OPOST processing and putting the results in the
446 * tty driver's write buffer.
448 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
449 * and NLDLY. They simply aren't relevant in the world today.
450 * If you ever need them, add them here.
452 * Returns the number of bytes of buffer space used or -1 if
455 * Locking: should be called under the output_lock to protect
456 * the column state and space left in the buffer
459 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
461 struct n_tty_data
*ldata
= tty
->disc_data
;
474 ldata
->canon_column
= ldata
->column
= 0;
475 tty
->ops
->write(tty
, "\r\n", 2);
478 ldata
->canon_column
= ldata
->column
;
481 if (O_ONOCR(tty
) && ldata
->column
== 0)
486 ldata
->canon_column
= ldata
->column
= 0;
489 ldata
->canon_column
= ldata
->column
= 0;
492 spaces
= 8 - (ldata
->column
& 7);
493 if (O_TABDLY(tty
) == XTABS
) {
496 ldata
->column
+= spaces
;
497 tty
->ops
->write(tty
, " ", spaces
);
500 ldata
->column
+= spaces
;
503 if (ldata
->column
> 0)
510 if (!is_continuation(c
, tty
))
516 tty_put_char(tty
, c
);
521 * process_output - output post processor
522 * @c: character (or partial unicode symbol)
523 * @tty: terminal device
525 * Output one character with OPOST processing.
526 * Returns -1 when the output device is full and the character
529 * Locking: output_lock to protect column state and space left
530 * (also, this is called from n_tty_write under the
531 * tty layer write lock)
534 static int process_output(unsigned char c
, struct tty_struct
*tty
)
536 struct n_tty_data
*ldata
= tty
->disc_data
;
539 mutex_lock(&ldata
->output_lock
);
541 space
= tty_write_room(tty
);
542 retval
= do_output_char(c
, tty
, space
);
544 mutex_unlock(&ldata
->output_lock
);
552 * process_output_block - block post processor
553 * @tty: terminal device
554 * @buf: character buffer
555 * @nr: number of bytes to output
557 * Output a block of characters with OPOST processing.
558 * Returns the number of characters output.
560 * This path is used to speed up block console writes, among other
561 * things when processing blocks of output data. It handles only
562 * the simple cases normally found and helps to generate blocks of
563 * symbols for the console driver and thus improve performance.
565 * Locking: output_lock to protect column state and space left
566 * (also, this is called from n_tty_write under the
567 * tty layer write lock)
570 static ssize_t
process_output_block(struct tty_struct
*tty
,
571 const unsigned char *buf
, unsigned int nr
)
573 struct n_tty_data
*ldata
= tty
->disc_data
;
576 const unsigned char *cp
;
578 mutex_lock(&ldata
->output_lock
);
580 space
= tty_write_room(tty
);
582 mutex_unlock(&ldata
->output_lock
);
588 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
589 unsigned char c
= *cp
;
597 ldata
->canon_column
= ldata
->column
;
600 if (O_ONOCR(tty
) && ldata
->column
== 0)
604 ldata
->canon_column
= ldata
->column
= 0;
609 if (ldata
->column
> 0)
616 if (!is_continuation(c
, tty
))
623 i
= tty
->ops
->write(tty
, buf
, i
);
625 mutex_unlock(&ldata
->output_lock
);
630 * process_echoes - write pending echo characters
631 * @tty: terminal device
633 * Write previously buffered echo (and other ldisc-generated)
634 * characters to the tty.
636 * Characters generated by the ldisc (including echoes) need to
637 * be buffered because the driver's write buffer can fill during
638 * heavy program output. Echoing straight to the driver will
639 * often fail under these conditions, causing lost characters and
640 * resulting mismatches of ldisc state information.
642 * Since the ldisc state must represent the characters actually sent
643 * to the driver at the time of the write, operations like certain
644 * changes in column state are also saved in the buffer and executed
647 * A circular fifo buffer is used so that the most recent characters
648 * are prioritized. Also, when control characters are echoed with a
649 * prefixed "^", the pair is treated atomically and thus not separated.
651 * Locking: callers must hold output_lock
654 static size_t __process_echoes(struct tty_struct
*tty
)
656 struct n_tty_data
*ldata
= tty
->disc_data
;
657 int space
, old_space
;
661 old_space
= space
= tty_write_room(tty
);
663 tail
= ldata
->echo_tail
;
664 while (ldata
->echo_commit
!= tail
) {
665 c
= echo_buf(ldata
, tail
);
666 if (c
== ECHO_OP_START
) {
668 int no_space_left
= 0;
671 * If the buffer byte is the start of a multi-byte
672 * operation, get the next byte, which is either the
673 * op code or a control character value.
675 op
= echo_buf(ldata
, tail
+ 1);
678 unsigned int num_chars
, num_bs
;
680 case ECHO_OP_ERASE_TAB
:
681 num_chars
= echo_buf(ldata
, tail
+ 2);
684 * Determine how many columns to go back
685 * in order to erase the tab.
686 * This depends on the number of columns
687 * used by other characters within the tab
688 * area. If this (modulo 8) count is from
689 * the start of input rather than from a
690 * previous tab, we offset by canon column.
691 * Otherwise, tab spacing is normal.
693 if (!(num_chars
& 0x80))
694 num_chars
+= ldata
->canon_column
;
695 num_bs
= 8 - (num_chars
& 7);
697 if (num_bs
> space
) {
703 tty_put_char(tty
, '\b');
704 if (ldata
->column
> 0)
710 case ECHO_OP_SET_CANON_COL
:
711 ldata
->canon_column
= ldata
->column
;
715 case ECHO_OP_MOVE_BACK_COL
:
716 if (ldata
->column
> 0)
722 /* This is an escaped echo op start code */
727 tty_put_char(tty
, ECHO_OP_START
);
735 * If the op is not a special byte code,
736 * it is a ctrl char tagged to be echoed
737 * as "^X" (where X is the letter
738 * representing the control char).
739 * Note that we must ensure there is
740 * enough space for the whole ctrl pair.
747 tty_put_char(tty
, '^');
748 tty_put_char(tty
, op
^ 0100);
758 int retval
= do_output_char(c
, tty
, space
);
765 tty_put_char(tty
, c
);
772 /* If the echo buffer is nearly full (so that the possibility exists
773 * of echo overrun before the next commit), then discard enough
774 * data at the tail to prevent a subsequent overrun */
775 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
776 if (echo_buf(ldata
, tail
) == ECHO_OP_START
) {
777 if (echo_buf(ldata
, tail
+ 1) == ECHO_OP_ERASE_TAB
)
785 ldata
->echo_tail
= tail
;
786 return old_space
- space
;
789 static void commit_echoes(struct tty_struct
*tty
)
791 struct n_tty_data
*ldata
= tty
->disc_data
;
792 size_t nr
, old
, echoed
;
795 head
= ldata
->echo_head
;
796 ldata
->echo_mark
= head
;
797 old
= ldata
->echo_commit
- ldata
->echo_tail
;
799 /* Process committed echoes if the accumulated # of bytes
800 * is over the threshold (and try again each time another
801 * block is accumulated) */
802 nr
= head
- ldata
->echo_tail
;
803 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
806 mutex_lock(&ldata
->output_lock
);
807 ldata
->echo_commit
= head
;
808 echoed
= __process_echoes(tty
);
809 mutex_unlock(&ldata
->output_lock
);
811 if (echoed
&& tty
->ops
->flush_chars
)
812 tty
->ops
->flush_chars(tty
);
815 static void process_echoes(struct tty_struct
*tty
)
817 struct n_tty_data
*ldata
= tty
->disc_data
;
820 if (ldata
->echo_mark
== ldata
->echo_tail
)
823 mutex_lock(&ldata
->output_lock
);
824 ldata
->echo_commit
= ldata
->echo_mark
;
825 echoed
= __process_echoes(tty
);
826 mutex_unlock(&ldata
->output_lock
);
828 if (echoed
&& tty
->ops
->flush_chars
)
829 tty
->ops
->flush_chars(tty
);
832 /* NB: echo_mark and echo_head should be equivalent here */
833 static void flush_echoes(struct tty_struct
*tty
)
835 struct n_tty_data
*ldata
= tty
->disc_data
;
837 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
838 ldata
->echo_commit
== ldata
->echo_head
)
841 mutex_lock(&ldata
->output_lock
);
842 ldata
->echo_commit
= ldata
->echo_head
;
843 __process_echoes(tty
);
844 mutex_unlock(&ldata
->output_lock
);
848 * add_echo_byte - add a byte to the echo buffer
849 * @c: unicode byte to echo
852 * Add a character or operation byte to the echo buffer.
855 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
857 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
861 * echo_move_back_col - add operation to move back a column
864 * Add an operation to the echo buffer to move back one column.
867 static void echo_move_back_col(struct n_tty_data
*ldata
)
869 add_echo_byte(ECHO_OP_START
, ldata
);
870 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
874 * echo_set_canon_col - add operation to set the canon column
877 * Add an operation to the echo buffer to set the canon column
878 * to the current column.
881 static void echo_set_canon_col(struct n_tty_data
*ldata
)
883 add_echo_byte(ECHO_OP_START
, ldata
);
884 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
888 * echo_erase_tab - add operation to erase a tab
889 * @num_chars: number of character columns already used
890 * @after_tab: true if num_chars starts after a previous tab
893 * Add an operation to the echo buffer to erase a tab.
895 * Called by the eraser function, which knows how many character
896 * columns have been used since either a previous tab or the start
897 * of input. This information will be used later, along with
898 * canon column (if applicable), to go back the correct number
902 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
903 struct n_tty_data
*ldata
)
905 add_echo_byte(ECHO_OP_START
, ldata
);
906 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
908 /* We only need to know this modulo 8 (tab spacing) */
911 /* Set the high bit as a flag if num_chars is after a previous tab */
915 add_echo_byte(num_chars
, ldata
);
919 * echo_char_raw - echo a character raw
920 * @c: unicode byte to echo
921 * @tty: terminal device
923 * Echo user input back onto the screen. This must be called only when
924 * L_ECHO(tty) is true. Called from the driver receive_buf path.
926 * This variant does not treat control characters specially.
929 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
931 if (c
== ECHO_OP_START
) {
932 add_echo_byte(ECHO_OP_START
, ldata
);
933 add_echo_byte(ECHO_OP_START
, ldata
);
935 add_echo_byte(c
, ldata
);
940 * echo_char - echo a character
941 * @c: unicode byte to echo
942 * @tty: terminal device
944 * Echo user input back onto the screen. This must be called only when
945 * L_ECHO(tty) is true. Called from the driver receive_buf path.
947 * This variant tags control characters to be echoed as "^X"
948 * (where X is the letter representing the control char).
951 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
953 struct n_tty_data
*ldata
= tty
->disc_data
;
955 if (c
== ECHO_OP_START
) {
956 add_echo_byte(ECHO_OP_START
, ldata
);
957 add_echo_byte(ECHO_OP_START
, ldata
);
959 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
960 add_echo_byte(ECHO_OP_START
, ldata
);
961 add_echo_byte(c
, ldata
);
966 * finish_erasing - complete erase
970 static inline void finish_erasing(struct n_tty_data
*ldata
)
972 if (ldata
->erasing
) {
973 echo_char_raw('/', ldata
);
979 * eraser - handle erase function
980 * @c: character input
981 * @tty: terminal device
983 * Perform erase and necessary output when an erase character is
984 * present in the stream from the driver layer. Handles the complexities
985 * of UTF-8 multibyte symbols.
987 * n_tty_receive_buf()/producer path:
988 * caller holds non-exclusive termios_rwsem
991 * Modifying the read_head is not considered a publish in this context
992 * because canonical mode is active -- only canon_head publishes
995 static void eraser(unsigned char c
, struct tty_struct
*tty
)
997 struct n_tty_data
*ldata
= tty
->disc_data
;
998 enum { ERASE
, WERASE
, KILL
} kill_type
;
1003 if (ldata
->read_head
== ldata
->canon_head
) {
1004 /* process_output('\a', tty); */ /* what do you think? */
1007 if (c
== ERASE_CHAR(tty
))
1009 else if (c
== WERASE_CHAR(tty
))
1013 ldata
->read_head
= ldata
->canon_head
;
1016 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1017 ldata
->read_head
= ldata
->canon_head
;
1018 finish_erasing(ldata
);
1019 echo_char(KILL_CHAR(tty
), tty
);
1020 /* Add a newline if ECHOK is on and ECHOKE is off. */
1022 echo_char_raw('\n', ldata
);
1029 while (ldata
->read_head
!= ldata
->canon_head
) {
1030 head
= ldata
->read_head
;
1032 /* erase a single possibly multibyte character */
1035 c
= read_buf(ldata
, head
);
1036 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1038 /* do not partially erase */
1039 if (is_continuation(c
, tty
))
1042 if (kill_type
== WERASE
) {
1043 /* Equivalent to BSD's ALTWERASE. */
1044 if (isalnum(c
) || c
== '_')
1046 else if (seen_alnums
)
1049 cnt
= ldata
->read_head
- head
;
1050 ldata
->read_head
= head
;
1052 if (L_ECHOPRT(tty
)) {
1053 if (!ldata
->erasing
) {
1054 echo_char_raw('\\', ldata
);
1057 /* if cnt > 1, output a multi-byte character */
1061 echo_char_raw(read_buf(ldata
, head
), ldata
);
1062 echo_move_back_col(ldata
);
1064 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1065 echo_char(ERASE_CHAR(tty
), tty
);
1066 } else if (c
== '\t') {
1067 unsigned int num_chars
= 0;
1069 size_t tail
= ldata
->read_head
;
1072 * Count the columns used for characters
1073 * since the start of input or after a
1075 * This info is used to go back the correct
1076 * number of columns.
1078 while (tail
!= ldata
->canon_head
) {
1080 c
= read_buf(ldata
, tail
);
1084 } else if (iscntrl(c
)) {
1087 } else if (!is_continuation(c
, tty
)) {
1091 echo_erase_tab(num_chars
, after_tab
, ldata
);
1093 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1094 echo_char_raw('\b', ldata
);
1095 echo_char_raw(' ', ldata
);
1096 echo_char_raw('\b', ldata
);
1098 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1099 echo_char_raw('\b', ldata
);
1100 echo_char_raw(' ', ldata
);
1101 echo_char_raw('\b', ldata
);
1105 if (kill_type
== ERASE
)
1108 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1109 finish_erasing(ldata
);
1113 * isig - handle the ISIG optio
1117 * Called when a signal is being sent due to terminal input.
1118 * Called from the driver receive_buf path so serialized.
1120 * Locking: ctrl_lock
1123 static void isig(int sig
, struct tty_struct
*tty
)
1125 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1127 kill_pgrp(tty_pgrp
, sig
, 1);
1133 * n_tty_receive_break - handle break
1136 * An RS232 break event has been hit in the incoming bitstream. This
1137 * can cause a variety of events depending upon the termios settings.
1139 * n_tty_receive_buf()/producer path:
1140 * caller holds non-exclusive termios_rwsem
1141 * publishes read_head via put_tty_queue()
1143 * Note: may get exclusive termios_rwsem if flushing input buffer
1146 static void n_tty_receive_break(struct tty_struct
*tty
)
1148 struct n_tty_data
*ldata
= tty
->disc_data
;
1152 if (I_BRKINT(tty
)) {
1154 if (!L_NOFLSH(tty
)) {
1155 /* flushing needs exclusive termios_rwsem */
1156 up_read(&tty
->termios_rwsem
);
1157 n_tty_flush_buffer(tty
);
1158 tty_driver_flush_buffer(tty
);
1159 down_read(&tty
->termios_rwsem
);
1163 if (I_PARMRK(tty
)) {
1164 put_tty_queue('\377', ldata
);
1165 put_tty_queue('\0', ldata
);
1167 put_tty_queue('\0', ldata
);
1168 if (waitqueue_active(&tty
->read_wait
))
1169 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1173 * n_tty_receive_overrun - handle overrun reporting
1176 * Data arrived faster than we could process it. While the tty
1177 * driver has flagged this the bits that were missed are gone
1180 * Called from the receive_buf path so single threaded. Does not
1181 * need locking as num_overrun and overrun_time are function
1185 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1187 struct n_tty_data
*ldata
= tty
->disc_data
;
1190 ldata
->num_overrun
++;
1191 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1192 time_after(ldata
->overrun_time
, jiffies
)) {
1193 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1195 ldata
->num_overrun
);
1196 ldata
->overrun_time
= jiffies
;
1197 ldata
->num_overrun
= 0;
1202 * n_tty_receive_parity_error - error notifier
1203 * @tty: terminal device
1206 * Process a parity error and queue the right data to indicate
1207 * the error case if necessary.
1209 * n_tty_receive_buf()/producer path:
1210 * caller holds non-exclusive termios_rwsem
1211 * publishes read_head via put_tty_queue()
1213 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1215 struct n_tty_data
*ldata
= tty
->disc_data
;
1220 if (I_PARMRK(tty
)) {
1221 put_tty_queue('\377', ldata
);
1222 put_tty_queue('\0', ldata
);
1223 put_tty_queue(c
, ldata
);
1225 put_tty_queue('\0', ldata
);
1227 put_tty_queue(c
, ldata
);
1228 if (waitqueue_active(&tty
->read_wait
))
1229 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1233 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1235 if (!L_NOFLSH(tty
)) {
1236 /* flushing needs exclusive termios_rwsem */
1237 up_read(&tty
->termios_rwsem
);
1238 n_tty_flush_buffer(tty
);
1239 tty_driver_flush_buffer(tty
);
1240 down_read(&tty
->termios_rwsem
);
1248 process_echoes(tty
);
1254 * n_tty_receive_char - perform processing
1255 * @tty: terminal device
1258 * Process an individual character of input received from the driver.
1259 * This is serialized with respect to itself by the rules for the
1262 * n_tty_receive_buf()/producer path:
1263 * caller holds non-exclusive termios_rwsem
1264 * publishes canon_head if canonical mode is active
1265 * otherwise, publishes read_head via put_tty_queue()
1267 * Returns 1 if LNEXT was received, else returns 0
1271 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1273 struct n_tty_data
*ldata
= tty
->disc_data
;
1276 if (c
== START_CHAR(tty
)) {
1278 process_echoes(tty
);
1281 if (c
== STOP_CHAR(tty
)) {
1288 if (c
== INTR_CHAR(tty
)) {
1289 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1291 } else if (c
== QUIT_CHAR(tty
)) {
1292 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1294 } else if (c
== SUSP_CHAR(tty
)) {
1295 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1300 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1302 process_echoes(tty
);
1310 } else if (c
== '\n' && I_INLCR(tty
))
1313 if (ldata
->icanon
) {
1314 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1315 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1320 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1323 finish_erasing(ldata
);
1324 if (L_ECHOCTL(tty
)) {
1325 echo_char_raw('^', ldata
);
1326 echo_char_raw('\b', ldata
);
1332 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1333 size_t tail
= ldata
->canon_head
;
1335 finish_erasing(ldata
);
1337 echo_char_raw('\n', ldata
);
1338 while (tail
!= ldata
->read_head
) {
1339 echo_char(read_buf(ldata
, tail
), tty
);
1346 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1347 echo_char_raw('\n', ldata
);
1350 goto handle_newline
;
1352 if (c
== EOF_CHAR(tty
)) {
1353 c
= __DISABLED_CHAR
;
1354 goto handle_newline
;
1356 if ((c
== EOL_CHAR(tty
)) ||
1357 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1359 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1362 /* Record the column of first canon char. */
1363 if (ldata
->canon_head
== ldata
->read_head
)
1364 echo_set_canon_col(ldata
);
1369 * XXX does PARMRK doubling happen for
1370 * EOL_CHAR and EOL2_CHAR?
1372 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1373 put_tty_queue(c
, ldata
);
1376 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1377 put_tty_queue(c
, ldata
);
1378 ldata
->canon_head
= ldata
->read_head
;
1379 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1380 if (waitqueue_active(&tty
->read_wait
))
1381 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1387 finish_erasing(ldata
);
1389 echo_char_raw('\n', ldata
);
1391 /* Record the column of first canon char. */
1392 if (ldata
->canon_head
== ldata
->read_head
)
1393 echo_set_canon_col(ldata
);
1399 /* PARMRK doubling check */
1400 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1401 put_tty_queue(c
, ldata
);
1403 put_tty_queue(c
, ldata
);
1408 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1410 struct n_tty_data
*ldata
= tty
->disc_data
;
1412 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1414 process_echoes(tty
);
1417 finish_erasing(ldata
);
1418 /* Record the column of first canon char. */
1419 if (ldata
->canon_head
== ldata
->read_head
)
1420 echo_set_canon_col(ldata
);
1424 /* PARMRK doubling check */
1425 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1426 put_tty_queue(c
, ldata
);
1427 put_tty_queue(c
, ldata
);
1430 static void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1432 n_tty_receive_char_inline(tty
, c
);
1436 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1438 struct n_tty_data
*ldata
= tty
->disc_data
;
1440 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1442 process_echoes(tty
);
1445 finish_erasing(ldata
);
1446 /* Record the column of first canon char. */
1447 if (ldata
->canon_head
== ldata
->read_head
)
1448 echo_set_canon_col(ldata
);
1452 put_tty_queue(c
, ldata
);
1455 static void n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1459 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1463 if (c
== STOP_CHAR(tty
))
1465 else if (c
== START_CHAR(tty
) ||
1466 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1467 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1468 c
!= SUSP_CHAR(tty
))) {
1470 process_echoes(tty
);
1476 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1482 n_tty_receive_break(tty
);
1486 n_tty_receive_parity_error(tty
, c
);
1489 n_tty_receive_overrun(tty
);
1492 printk(KERN_ERR
"%s: unknown flag %d\n",
1493 tty_name(tty
, buf
), flag
);
1499 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1501 struct n_tty_data
*ldata
= tty
->disc_data
;
1504 if (likely(flag
== TTY_NORMAL
)) {
1507 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1509 n_tty_receive_char(tty
, c
);
1511 n_tty_receive_char_flagged(tty
, c
, flag
);
1515 * n_tty_receive_buf - data receive
1516 * @tty: terminal device
1519 * @count: characters
1521 * Called by the terminal driver when a block of characters has
1522 * been received. This function must be called from soft contexts
1523 * not from interrupt context. The driver is responsible for making
1524 * calls one at a time and in order (or using flush_to_ldisc)
1526 * n_tty_receive_buf()/producer path:
1527 * claims non-exclusive termios_rwsem
1528 * publishes read_head and canon_head
1532 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1533 char *fp
, int count
)
1535 struct n_tty_data
*ldata
= tty
->disc_data
;
1538 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1539 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1540 n
= min_t(size_t, count
, n
);
1541 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1542 ldata
->read_head
+= n
;
1546 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1547 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1548 n
= min_t(size_t, count
, n
);
1549 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1550 ldata
->read_head
+= n
;
1554 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1555 char *fp
, int count
)
1557 struct n_tty_data
*ldata
= tty
->disc_data
;
1558 char flag
= TTY_NORMAL
;
1563 if (likely(flag
== TTY_NORMAL
))
1564 put_tty_queue(*cp
++, ldata
);
1566 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1571 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1572 char *fp
, int count
)
1574 char flag
= TTY_NORMAL
;
1579 if (likely(flag
== TTY_NORMAL
))
1580 n_tty_receive_char_closing(tty
, *cp
++);
1582 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1587 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1588 char *fp
, int count
)
1590 struct n_tty_data
*ldata
= tty
->disc_data
;
1591 char flag
= TTY_NORMAL
;
1596 if (likely(flag
== TTY_NORMAL
)) {
1597 unsigned char c
= *cp
++;
1601 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1603 if (L_EXTPROC(tty
)) {
1604 put_tty_queue(c
, ldata
);
1607 if (!test_bit(c
, ldata
->char_map
))
1608 n_tty_receive_char_inline(tty
, c
);
1609 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1612 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1616 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1621 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1622 char *fp
, int count
)
1624 struct n_tty_data
*ldata
= tty
->disc_data
;
1625 char flag
= TTY_NORMAL
;
1630 if (likely(flag
== TTY_NORMAL
)) {
1631 unsigned char c
= *cp
++;
1633 if (!test_bit(c
, ldata
->char_map
))
1634 n_tty_receive_char_fast(tty
, c
);
1635 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1638 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1642 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1646 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1647 char *fp
, int count
)
1649 struct n_tty_data
*ldata
= tty
->disc_data
;
1650 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1652 if (ldata
->real_raw
)
1653 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1654 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1655 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1656 else if (tty
->closing
&& !L_EXTPROC(tty
))
1657 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1660 char flag
= TTY_NORMAL
;
1664 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1668 if (!preops
&& !I_PARMRK(tty
))
1669 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1671 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1674 if (tty
->ops
->flush_chars
)
1675 tty
->ops
->flush_chars(tty
);
1678 if ((!ldata
->icanon
&& (read_cnt(ldata
) >= ldata
->minimum_to_wake
)) ||
1680 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1681 if (waitqueue_active(&tty
->read_wait
))
1682 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1687 n_tty_receive_buf_common(struct tty_struct
*tty
, const unsigned char *cp
,
1688 char *fp
, int count
, int flow
)
1690 struct n_tty_data
*ldata
= tty
->disc_data
;
1691 int room
, n
, rcvd
= 0;
1693 down_read(&tty
->termios_rwsem
);
1696 room
= receive_room(tty
);
1697 n
= min(count
, room
);
1703 __receive_buf(tty
, cp
, fp
, n
);
1711 tty
->receive_room
= room
;
1712 n_tty_check_throttle(tty
);
1713 up_read(&tty
->termios_rwsem
);
1718 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1719 char *fp
, int count
)
1721 n_tty_receive_buf_common(tty
, cp
, fp
, count
, 0);
1724 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1725 char *fp
, int count
)
1727 return n_tty_receive_buf_common(tty
, cp
, fp
, count
, 1);
1730 int is_ignored(int sig
)
1732 return (sigismember(¤t
->blocked
, sig
) ||
1733 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1737 * n_tty_set_termios - termios data changed
1739 * @old: previous data
1741 * Called by the tty layer when the user changes termios flags so
1742 * that the line discipline can plan ahead. This function cannot sleep
1743 * and is protected from re-entry by the tty layer. The user is
1744 * guaranteed that this function will not be re-entered or in progress
1745 * when the ldisc is closed.
1747 * Locking: Caller holds tty->termios_rwsem
1750 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1752 struct n_tty_data
*ldata
= tty
->disc_data
;
1754 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1755 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1756 ldata
->line_start
= ldata
->read_tail
;
1757 if (!L_ICANON(tty
) || !read_cnt(ldata
)) {
1758 ldata
->canon_head
= ldata
->read_tail
;
1761 set_bit((ldata
->read_head
- 1) & (N_TTY_BUF_SIZE
- 1),
1763 ldata
->canon_head
= ldata
->read_head
;
1770 ldata
->icanon
= (L_ICANON(tty
) != 0);
1772 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1773 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1774 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1776 bitmap_zero(ldata
->char_map
, 256);
1778 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1779 set_bit('\r', ldata
->char_map
);
1781 set_bit('\n', ldata
->char_map
);
1783 if (L_ICANON(tty
)) {
1784 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1785 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1786 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1787 set_bit('\n', ldata
->char_map
);
1788 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1789 if (L_IEXTEN(tty
)) {
1790 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1791 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1792 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1794 set_bit(REPRINT_CHAR(tty
),
1799 set_bit(START_CHAR(tty
), ldata
->char_map
);
1800 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1803 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1804 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1805 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1807 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1809 ldata
->real_raw
= 0;
1812 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1813 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1814 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1815 ldata
->real_raw
= 1;
1817 ldata
->real_raw
= 0;
1819 n_tty_set_room(tty
);
1821 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1822 * been stopped by STOP_CHAR(tty) before it.
1824 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1826 process_echoes(tty
);
1829 /* The termios change make the tty ready for I/O */
1830 if (waitqueue_active(&tty
->write_wait
))
1831 wake_up_interruptible(&tty
->write_wait
);
1832 if (waitqueue_active(&tty
->read_wait
))
1833 wake_up_interruptible(&tty
->read_wait
);
1837 * n_tty_close - close the ldisc for this tty
1840 * Called from the terminal layer when this line discipline is
1841 * being shut down, either because of a close or becsuse of a
1842 * discipline change. The function will not be called while other
1843 * ldisc methods are in progress.
1846 static void n_tty_close(struct tty_struct
*tty
)
1848 struct n_tty_data
*ldata
= tty
->disc_data
;
1851 n_tty_packet_mode_flush(tty
);
1854 tty
->disc_data
= NULL
;
1858 * n_tty_open - open an ldisc
1859 * @tty: terminal to open
1861 * Called when this line discipline is being attached to the
1862 * terminal device. Can sleep. Called serialized so that no
1863 * other events will occur in parallel. No further open will occur
1867 static int n_tty_open(struct tty_struct
*tty
)
1869 struct n_tty_data
*ldata
;
1871 /* Currently a malloc failure here can panic */
1872 ldata
= vmalloc(sizeof(*ldata
));
1876 ldata
->overrun_time
= jiffies
;
1877 mutex_init(&ldata
->atomic_read_lock
);
1878 mutex_init(&ldata
->output_lock
);
1880 tty
->disc_data
= ldata
;
1881 reset_buffer_flags(tty
->disc_data
);
1883 ldata
->canon_column
= 0;
1884 ldata
->minimum_to_wake
= 1;
1885 ldata
->num_overrun
= 0;
1889 /* indicate buffer work may resume */
1890 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1891 n_tty_set_termios(tty
, NULL
);
1892 tty_unthrottle(tty
);
1899 static inline int input_available_p(struct tty_struct
*tty
, int poll
)
1901 struct n_tty_data
*ldata
= tty
->disc_data
;
1902 int amt
= poll
&& !TIME_CHAR(tty
) && MIN_CHAR(tty
) ? MIN_CHAR(tty
) : 1;
1904 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1905 return ldata
->canon_head
!= ldata
->read_tail
;
1907 return read_cnt(ldata
) >= amt
;
1911 * copy_from_read_buf - copy read data directly
1912 * @tty: terminal device
1916 * Helper function to speed up n_tty_read. It is only called when
1917 * ICANON is off; it copies characters straight from the tty queue to
1918 * user space directly. It can be profitably called twice; once to
1919 * drain the space from the tail pointer to the (physical) end of the
1920 * buffer, and once to drain the space from the (physical) beginning of
1921 * the buffer to head pointer.
1923 * Called under the ldata->atomic_read_lock sem
1925 * n_tty_read()/consumer path:
1926 * caller holds non-exclusive termios_rwsem
1927 * read_tail published
1930 static int copy_from_read_buf(struct tty_struct
*tty
,
1931 unsigned char __user
**b
,
1935 struct n_tty_data
*ldata
= tty
->disc_data
;
1939 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1942 n
= min(read_cnt(ldata
), N_TTY_BUF_SIZE
- tail
);
1945 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1947 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
1948 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
1950 ldata
->read_tail
+= n
;
1951 /* Turn single EOF into zero-length read */
1952 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&& !read_cnt(ldata
))
1961 * canon_copy_from_read_buf - copy read data in canonical mode
1962 * @tty: terminal device
1966 * Helper function for n_tty_read. It is only called when ICANON is on;
1967 * it copies one line of input up to and including the line-delimiting
1968 * character into the user-space buffer.
1970 * NB: When termios is changed from non-canonical to canonical mode and
1971 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1972 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1973 * This causes data already processed as input to be immediately available
1974 * as input although a newline has not been received.
1976 * Called under the atomic_read_lock mutex
1978 * n_tty_read()/consumer path:
1979 * caller holds non-exclusive termios_rwsem
1980 * read_tail published
1983 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
1984 unsigned char __user
**b
,
1987 struct n_tty_data
*ldata
= tty
->disc_data
;
1988 size_t n
, size
, more
, c
;
1994 /* N.B. avoid overrun if nr == 0 */
1995 n
= min(*nr
, read_cnt(ldata
));
1999 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2000 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
2002 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2003 __func__
, *nr
, tail
, n
, size
);
2005 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
2006 more
= n
- (size
- tail
);
2007 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2008 /* scan wrapped without finding set bit */
2009 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2012 } else if (eol
!= size
)
2015 size
= N_TTY_BUF_SIZE
- tail
;
2022 if (found
&& !ldata
->push
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
2024 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
2027 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2028 __func__
, eol
, found
, n
, c
, size
, more
);
2031 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), size
);
2034 ret
= copy_to_user(*b
+ size
, ldata
->read_buf
, n
- size
);
2036 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2044 clear_bit(eol
, ldata
->read_flags
);
2045 smp_mb__after_atomic();
2046 ldata
->read_tail
+= c
;
2050 ldata
->line_start
= ldata
->read_tail
;
2053 tty_audit_push(tty
);
2055 return eof_push
? -EAGAIN
: 0;
2058 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2062 * job_control - check job control
2064 * @file: file handle
2066 * Perform job control management checks on this file/tty descriptor
2067 * and if appropriate send any needed signals and return a negative
2068 * error code if action should be taken.
2070 * Locking: redirected write test is safe
2071 * current->signal->tty check is safe
2072 * ctrl_lock to safely reference tty->pgrp
2075 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2077 /* Job control check -- must be done at start and after
2078 every sleep (POSIX.1 7.1.1.4). */
2079 /* NOTE: not yet done after every sleep pending a thorough
2080 check of the logic of this change. -- jlc */
2081 /* don't stop on /dev/console */
2082 if (file
->f_op
->write
== redirected_tty_write
||
2083 current
->signal
->tty
!= tty
)
2086 spin_lock_irq(&tty
->ctrl_lock
);
2088 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2089 else if (task_pgrp(current
) != tty
->pgrp
) {
2090 spin_unlock_irq(&tty
->ctrl_lock
);
2091 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
2093 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
2094 set_thread_flag(TIF_SIGPENDING
);
2095 return -ERESTARTSYS
;
2097 spin_unlock_irq(&tty
->ctrl_lock
);
2103 * n_tty_read - read function for tty
2105 * @file: file object
2106 * @buf: userspace buffer pointer
2109 * Perform reads for the line discipline. We are guaranteed that the
2110 * line discipline will not be closed under us but we may get multiple
2111 * parallel readers and must handle this ourselves. We may also get
2112 * a hangup. Always called in user context, may sleep.
2114 * This code must be sure never to sleep through a hangup.
2116 * n_tty_read()/consumer path:
2117 * claims non-exclusive termios_rwsem
2118 * publishes read_tail
2121 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2122 unsigned char __user
*buf
, size_t nr
)
2124 struct n_tty_data
*ldata
= tty
->disc_data
;
2125 unsigned char __user
*b
= buf
;
2126 DECLARE_WAITQUEUE(wait
, current
);
2131 unsigned long flags
;
2134 c
= job_control(tty
, file
);
2139 * Internal serialization of reads.
2141 if (file
->f_flags
& O_NONBLOCK
) {
2142 if (!mutex_trylock(&ldata
->atomic_read_lock
))
2145 if (mutex_lock_interruptible(&ldata
->atomic_read_lock
))
2146 return -ERESTARTSYS
;
2149 down_read(&tty
->termios_rwsem
);
2152 timeout
= MAX_SCHEDULE_TIMEOUT
;
2153 if (!ldata
->icanon
) {
2154 minimum
= MIN_CHAR(tty
);
2156 time
= (HZ
/ 10) * TIME_CHAR(tty
);
2158 ldata
->minimum_to_wake
= 1;
2159 else if (!waitqueue_active(&tty
->read_wait
) ||
2160 (ldata
->minimum_to_wake
> minimum
))
2161 ldata
->minimum_to_wake
= minimum
;
2163 timeout
= (HZ
/ 10) * TIME_CHAR(tty
);
2164 ldata
->minimum_to_wake
= minimum
= 1;
2168 packet
= tty
->packet
;
2170 add_wait_queue(&tty
->read_wait
, &wait
);
2172 /* First test for status change. */
2173 if (packet
&& tty
->link
->ctrl_status
) {
2177 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
2178 cs
= tty
->link
->ctrl_status
;
2179 tty
->link
->ctrl_status
= 0;
2180 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
2181 if (tty_put_user(tty
, cs
, b
++)) {
2189 /* This statement must be first before checking for input
2190 so that any interrupt will set the state back to
2192 set_current_state(TASK_INTERRUPTIBLE
);
2194 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2195 ((minimum
- (b
- buf
)) >= 1))
2196 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2198 if (!input_available_p(tty
, 0)) {
2199 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
2200 up_read(&tty
->termios_rwsem
);
2201 tty_flush_to_ldisc(tty
);
2202 down_read(&tty
->termios_rwsem
);
2203 if (!input_available_p(tty
, 0)) {
2208 if (tty_hung_up_p(file
))
2212 if (file
->f_flags
& O_NONBLOCK
) {
2216 if (signal_pending(current
)) {
2217 retval
= -ERESTARTSYS
;
2220 n_tty_set_room(tty
);
2221 up_read(&tty
->termios_rwsem
);
2223 timeout
= schedule_timeout(timeout
);
2225 down_read(&tty
->termios_rwsem
);
2229 __set_current_state(TASK_RUNNING
);
2231 /* Deal with packet mode. */
2232 if (packet
&& b
== buf
) {
2233 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2241 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2242 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2243 if (retval
== -EAGAIN
) {
2250 /* The copy function takes the read lock and handles
2251 locking internally for this case */
2252 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2253 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2260 n_tty_check_unthrottle(tty
);
2262 if (b
- buf
>= minimum
)
2267 n_tty_set_room(tty
);
2268 up_read(&tty
->termios_rwsem
);
2270 remove_wait_queue(&tty
->read_wait
, &wait
);
2271 if (!waitqueue_active(&tty
->read_wait
))
2272 ldata
->minimum_to_wake
= minimum
;
2274 mutex_unlock(&ldata
->atomic_read_lock
);
2276 __set_current_state(TASK_RUNNING
);
2284 * n_tty_write - write function for tty
2286 * @file: file object
2287 * @buf: userspace buffer pointer
2290 * Write function of the terminal device. This is serialized with
2291 * respect to other write callers but not to termios changes, reads
2292 * and other such events. Since the receive code will echo characters,
2293 * thus calling driver write methods, the output_lock is used in
2294 * the output processing functions called here as well as in the
2295 * echo processing function to protect the column state and space
2296 * left in the buffer.
2298 * This code must be sure never to sleep through a hangup.
2300 * Locking: output_lock to protect column state and space left
2301 * (note that the process_output*() functions take this
2305 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2306 const unsigned char *buf
, size_t nr
)
2308 const unsigned char *b
= buf
;
2309 DECLARE_WAITQUEUE(wait
, current
);
2313 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2314 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2315 retval
= tty_check_change(tty
);
2320 down_read(&tty
->termios_rwsem
);
2322 /* Write out any echoed characters that are still pending */
2323 process_echoes(tty
);
2325 add_wait_queue(&tty
->write_wait
, &wait
);
2327 set_current_state(TASK_INTERRUPTIBLE
);
2328 if (signal_pending(current
)) {
2329 retval
= -ERESTARTSYS
;
2332 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2338 ssize_t num
= process_output_block(tty
, b
, nr
);
2350 if (process_output(c
, tty
) < 0)
2354 if (tty
->ops
->flush_chars
)
2355 tty
->ops
->flush_chars(tty
);
2357 struct n_tty_data
*ldata
= tty
->disc_data
;
2360 mutex_lock(&ldata
->output_lock
);
2361 c
= tty
->ops
->write(tty
, b
, nr
);
2362 mutex_unlock(&ldata
->output_lock
);
2375 if (file
->f_flags
& O_NONBLOCK
) {
2379 up_read(&tty
->termios_rwsem
);
2383 down_read(&tty
->termios_rwsem
);
2386 __set_current_state(TASK_RUNNING
);
2387 remove_wait_queue(&tty
->write_wait
, &wait
);
2388 if (b
- buf
!= nr
&& tty
->fasync
)
2389 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2390 up_read(&tty
->termios_rwsem
);
2391 return (b
- buf
) ? b
- buf
: retval
;
2395 * n_tty_poll - poll method for N_TTY
2396 * @tty: terminal device
2397 * @file: file accessing it
2400 * Called when the line discipline is asked to poll() for data or
2401 * for special events. This code is not serialized with respect to
2402 * other events save open/close.
2404 * This code must be sure never to sleep through a hangup.
2405 * Called without the kernel lock held - fine
2408 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2411 struct n_tty_data
*ldata
= tty
->disc_data
;
2412 unsigned int mask
= 0;
2414 poll_wait(file
, &tty
->read_wait
, wait
);
2415 poll_wait(file
, &tty
->write_wait
, wait
);
2416 if (input_available_p(tty
, 1))
2417 mask
|= POLLIN
| POLLRDNORM
;
2418 if (tty
->packet
&& tty
->link
->ctrl_status
)
2419 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2420 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2422 if (tty_hung_up_p(file
))
2424 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2425 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2426 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2428 ldata
->minimum_to_wake
= 1;
2430 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2431 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2432 tty_write_room(tty
) > 0)
2433 mask
|= POLLOUT
| POLLWRNORM
;
2437 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2439 size_t nr
, head
, tail
;
2441 if (ldata
->canon_head
== ldata
->read_tail
)
2443 head
= ldata
->canon_head
;
2444 tail
= ldata
->read_tail
;
2446 /* Skip EOF-chars.. */
2447 while (head
!= tail
) {
2448 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2449 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2456 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2457 unsigned int cmd
, unsigned long arg
)
2459 struct n_tty_data
*ldata
= tty
->disc_data
;
2464 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2466 down_write(&tty
->termios_rwsem
);
2468 retval
= inq_canon(ldata
);
2470 retval
= read_cnt(ldata
);
2471 up_write(&tty
->termios_rwsem
);
2472 return put_user(retval
, (unsigned int __user
*) arg
);
2474 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2478 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2480 struct n_tty_data
*ldata
= tty
->disc_data
;
2482 if (!waitqueue_active(&tty
->read_wait
)) {
2484 ldata
->minimum_to_wake
= 1;
2485 else if (!tty
->fasync
)
2486 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2490 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2491 .magic
= TTY_LDISC_MAGIC
,
2494 .close
= n_tty_close
,
2495 .flush_buffer
= n_tty_flush_buffer
,
2496 .chars_in_buffer
= n_tty_chars_in_buffer
,
2498 .write
= n_tty_write
,
2499 .ioctl
= n_tty_ioctl
,
2500 .set_termios
= n_tty_set_termios
,
2502 .receive_buf
= n_tty_receive_buf
,
2503 .write_wakeup
= n_tty_write_wakeup
,
2504 .fasync
= n_tty_fasync
,
2505 .receive_buf2
= n_tty_receive_buf2
,
2509 * n_tty_inherit_ops - inherit N_TTY methods
2510 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2512 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2516 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2518 *ops
= tty_ldisc_N_TTY
;
2520 ops
->refcount
= ops
->flags
= 0;
2522 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);