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
;
329 * reset_buffer_flags - reset buffer state
330 * @tty: terminal to reset
332 * Reset the read buffer counters and clear the flags.
333 * Called from n_tty_open() and n_tty_flush_buffer().
335 * Locking: caller holds exclusive termios_rwsem
336 * (or locking is not required)
339 static void reset_buffer_flags(struct n_tty_data
*ldata
)
341 ldata
->read_head
= ldata
->canon_head
= ldata
->read_tail
= 0;
342 ldata
->echo_head
= ldata
->echo_tail
= ldata
->echo_commit
= 0;
343 ldata
->echo_mark
= 0;
344 ldata
->line_start
= 0;
347 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
351 static void n_tty_packet_mode_flush(struct tty_struct
*tty
)
355 if (tty
->link
->packet
) {
356 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
357 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
358 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
359 if (waitqueue_active(&tty
->link
->read_wait
))
360 wake_up_interruptible(&tty
->link
->read_wait
);
365 * n_tty_flush_buffer - clean input queue
366 * @tty: terminal device
368 * Flush the input buffer. Called when the tty layer wants the
369 * buffer flushed (eg at hangup) or when the N_TTY line discipline
370 * internally has to clean the pending queue (for example some signals).
372 * Holds termios_rwsem to exclude producer/consumer while
373 * buffer indices are reset.
375 * Locking: ctrl_lock, exclusive termios_rwsem
378 static void n_tty_flush_buffer(struct tty_struct
*tty
)
380 down_write(&tty
->termios_rwsem
);
381 reset_buffer_flags(tty
->disc_data
);
385 n_tty_packet_mode_flush(tty
);
386 up_write(&tty
->termios_rwsem
);
390 * n_tty_chars_in_buffer - report available bytes
393 * Report the number of characters buffered to be delivered to user
394 * at this instant in time.
396 * Locking: exclusive termios_rwsem
399 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
403 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__
);
405 down_write(&tty
->termios_rwsem
);
406 n
= chars_in_buffer(tty
);
407 up_write(&tty
->termios_rwsem
);
412 * is_utf8_continuation - utf8 multibyte check
415 * Returns true if the utf8 character 'c' is a multibyte continuation
416 * character. We use this to correctly compute the on screen size
417 * of the character when printing
420 static inline int is_utf8_continuation(unsigned char c
)
422 return (c
& 0xc0) == 0x80;
426 * is_continuation - multibyte check
429 * Returns true if the utf8 character 'c' is a multibyte continuation
430 * character and the terminal is in unicode mode.
433 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
435 return I_IUTF8(tty
) && is_utf8_continuation(c
);
439 * do_output_char - output one character
440 * @c: character (or partial unicode symbol)
441 * @tty: terminal device
442 * @space: space available in tty driver write buffer
444 * This is a helper function that handles one output character
445 * (including special characters like TAB, CR, LF, etc.),
446 * doing OPOST processing and putting the results in the
447 * tty driver's write buffer.
449 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
450 * and NLDLY. They simply aren't relevant in the world today.
451 * If you ever need them, add them here.
453 * Returns the number of bytes of buffer space used or -1 if
456 * Locking: should be called under the output_lock to protect
457 * the column state and space left in the buffer
460 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
462 struct n_tty_data
*ldata
= tty
->disc_data
;
475 ldata
->canon_column
= ldata
->column
= 0;
476 tty
->ops
->write(tty
, "\r\n", 2);
479 ldata
->canon_column
= ldata
->column
;
482 if (O_ONOCR(tty
) && ldata
->column
== 0)
487 ldata
->canon_column
= ldata
->column
= 0;
490 ldata
->canon_column
= ldata
->column
= 0;
493 spaces
= 8 - (ldata
->column
& 7);
494 if (O_TABDLY(tty
) == XTABS
) {
497 ldata
->column
+= spaces
;
498 tty
->ops
->write(tty
, " ", spaces
);
501 ldata
->column
+= spaces
;
504 if (ldata
->column
> 0)
511 if (!is_continuation(c
, tty
))
517 tty_put_char(tty
, c
);
522 * process_output - output post processor
523 * @c: character (or partial unicode symbol)
524 * @tty: terminal device
526 * Output one character with OPOST processing.
527 * Returns -1 when the output device is full and the character
530 * Locking: output_lock to protect column state and space left
531 * (also, this is called from n_tty_write under the
532 * tty layer write lock)
535 static int process_output(unsigned char c
, struct tty_struct
*tty
)
537 struct n_tty_data
*ldata
= tty
->disc_data
;
540 mutex_lock(&ldata
->output_lock
);
542 space
= tty_write_room(tty
);
543 retval
= do_output_char(c
, tty
, space
);
545 mutex_unlock(&ldata
->output_lock
);
553 * process_output_block - block post processor
554 * @tty: terminal device
555 * @buf: character buffer
556 * @nr: number of bytes to output
558 * Output a block of characters with OPOST processing.
559 * Returns the number of characters output.
561 * This path is used to speed up block console writes, among other
562 * things when processing blocks of output data. It handles only
563 * the simple cases normally found and helps to generate blocks of
564 * symbols for the console driver and thus improve performance.
566 * Locking: output_lock to protect column state and space left
567 * (also, this is called from n_tty_write under the
568 * tty layer write lock)
571 static ssize_t
process_output_block(struct tty_struct
*tty
,
572 const unsigned char *buf
, unsigned int nr
)
574 struct n_tty_data
*ldata
= tty
->disc_data
;
577 const unsigned char *cp
;
579 mutex_lock(&ldata
->output_lock
);
581 space
= tty_write_room(tty
);
583 mutex_unlock(&ldata
->output_lock
);
589 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
590 unsigned char c
= *cp
;
598 ldata
->canon_column
= ldata
->column
;
601 if (O_ONOCR(tty
) && ldata
->column
== 0)
605 ldata
->canon_column
= ldata
->column
= 0;
610 if (ldata
->column
> 0)
617 if (!is_continuation(c
, tty
))
624 i
= tty
->ops
->write(tty
, buf
, i
);
626 mutex_unlock(&ldata
->output_lock
);
631 * process_echoes - write pending echo characters
632 * @tty: terminal device
634 * Write previously buffered echo (and other ldisc-generated)
635 * characters to the tty.
637 * Characters generated by the ldisc (including echoes) need to
638 * be buffered because the driver's write buffer can fill during
639 * heavy program output. Echoing straight to the driver will
640 * often fail under these conditions, causing lost characters and
641 * resulting mismatches of ldisc state information.
643 * Since the ldisc state must represent the characters actually sent
644 * to the driver at the time of the write, operations like certain
645 * changes in column state are also saved in the buffer and executed
648 * A circular fifo buffer is used so that the most recent characters
649 * are prioritized. Also, when control characters are echoed with a
650 * prefixed "^", the pair is treated atomically and thus not separated.
652 * Locking: callers must hold output_lock
655 static size_t __process_echoes(struct tty_struct
*tty
)
657 struct n_tty_data
*ldata
= tty
->disc_data
;
658 int space
, old_space
;
662 old_space
= space
= tty_write_room(tty
);
664 tail
= ldata
->echo_tail
;
665 while (ldata
->echo_commit
!= tail
) {
666 c
= echo_buf(ldata
, tail
);
667 if (c
== ECHO_OP_START
) {
669 int no_space_left
= 0;
672 * If the buffer byte is the start of a multi-byte
673 * operation, get the next byte, which is either the
674 * op code or a control character value.
676 op
= echo_buf(ldata
, tail
+ 1);
679 unsigned int num_chars
, num_bs
;
681 case ECHO_OP_ERASE_TAB
:
682 num_chars
= echo_buf(ldata
, tail
+ 2);
685 * Determine how many columns to go back
686 * in order to erase the tab.
687 * This depends on the number of columns
688 * used by other characters within the tab
689 * area. If this (modulo 8) count is from
690 * the start of input rather than from a
691 * previous tab, we offset by canon column.
692 * Otherwise, tab spacing is normal.
694 if (!(num_chars
& 0x80))
695 num_chars
+= ldata
->canon_column
;
696 num_bs
= 8 - (num_chars
& 7);
698 if (num_bs
> space
) {
704 tty_put_char(tty
, '\b');
705 if (ldata
->column
> 0)
711 case ECHO_OP_SET_CANON_COL
:
712 ldata
->canon_column
= ldata
->column
;
716 case ECHO_OP_MOVE_BACK_COL
:
717 if (ldata
->column
> 0)
723 /* This is an escaped echo op start code */
728 tty_put_char(tty
, ECHO_OP_START
);
736 * If the op is not a special byte code,
737 * it is a ctrl char tagged to be echoed
738 * as "^X" (where X is the letter
739 * representing the control char).
740 * Note that we must ensure there is
741 * enough space for the whole ctrl pair.
748 tty_put_char(tty
, '^');
749 tty_put_char(tty
, op
^ 0100);
759 int retval
= do_output_char(c
, tty
, space
);
766 tty_put_char(tty
, c
);
773 /* If the echo buffer is nearly full (so that the possibility exists
774 * of echo overrun before the next commit), then discard enough
775 * data at the tail to prevent a subsequent overrun */
776 while (ldata
->echo_commit
- tail
>= ECHO_DISCARD_WATERMARK
) {
777 if (echo_buf(ldata
, tail
) == ECHO_OP_START
) {
778 if (echo_buf(ldata
, tail
+ 1) == ECHO_OP_ERASE_TAB
)
786 ldata
->echo_tail
= tail
;
787 return old_space
- space
;
790 static void commit_echoes(struct tty_struct
*tty
)
792 struct n_tty_data
*ldata
= tty
->disc_data
;
793 size_t nr
, old
, echoed
;
796 head
= ldata
->echo_head
;
797 ldata
->echo_mark
= head
;
798 old
= ldata
->echo_commit
- ldata
->echo_tail
;
800 /* Process committed echoes if the accumulated # of bytes
801 * is over the threshold (and try again each time another
802 * block is accumulated) */
803 nr
= head
- ldata
->echo_tail
;
804 if (nr
< ECHO_COMMIT_WATERMARK
|| (nr
% ECHO_BLOCK
> old
% ECHO_BLOCK
))
807 mutex_lock(&ldata
->output_lock
);
808 ldata
->echo_commit
= head
;
809 echoed
= __process_echoes(tty
);
810 mutex_unlock(&ldata
->output_lock
);
812 if (echoed
&& tty
->ops
->flush_chars
)
813 tty
->ops
->flush_chars(tty
);
816 static void process_echoes(struct tty_struct
*tty
)
818 struct n_tty_data
*ldata
= tty
->disc_data
;
821 if (ldata
->echo_mark
== ldata
->echo_tail
)
824 mutex_lock(&ldata
->output_lock
);
825 ldata
->echo_commit
= ldata
->echo_mark
;
826 echoed
= __process_echoes(tty
);
827 mutex_unlock(&ldata
->output_lock
);
829 if (echoed
&& tty
->ops
->flush_chars
)
830 tty
->ops
->flush_chars(tty
);
833 /* NB: echo_mark and echo_head should be equivalent here */
834 static void flush_echoes(struct tty_struct
*tty
)
836 struct n_tty_data
*ldata
= tty
->disc_data
;
838 if ((!L_ECHO(tty
) && !L_ECHONL(tty
)) ||
839 ldata
->echo_commit
== ldata
->echo_head
)
842 mutex_lock(&ldata
->output_lock
);
843 ldata
->echo_commit
= ldata
->echo_head
;
844 __process_echoes(tty
);
845 mutex_unlock(&ldata
->output_lock
);
849 * add_echo_byte - add a byte to the echo buffer
850 * @c: unicode byte to echo
853 * Add a character or operation byte to the echo buffer.
856 static inline void add_echo_byte(unsigned char c
, struct n_tty_data
*ldata
)
858 *echo_buf_addr(ldata
, ldata
->echo_head
++) = c
;
862 * echo_move_back_col - add operation to move back a column
865 * Add an operation to the echo buffer to move back one column.
868 static void echo_move_back_col(struct n_tty_data
*ldata
)
870 add_echo_byte(ECHO_OP_START
, ldata
);
871 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, ldata
);
875 * echo_set_canon_col - add operation to set the canon column
878 * Add an operation to the echo buffer to set the canon column
879 * to the current column.
882 static void echo_set_canon_col(struct n_tty_data
*ldata
)
884 add_echo_byte(ECHO_OP_START
, ldata
);
885 add_echo_byte(ECHO_OP_SET_CANON_COL
, ldata
);
889 * echo_erase_tab - add operation to erase a tab
890 * @num_chars: number of character columns already used
891 * @after_tab: true if num_chars starts after a previous tab
894 * Add an operation to the echo buffer to erase a tab.
896 * Called by the eraser function, which knows how many character
897 * columns have been used since either a previous tab or the start
898 * of input. This information will be used later, along with
899 * canon column (if applicable), to go back the correct number
903 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
904 struct n_tty_data
*ldata
)
906 add_echo_byte(ECHO_OP_START
, ldata
);
907 add_echo_byte(ECHO_OP_ERASE_TAB
, ldata
);
909 /* We only need to know this modulo 8 (tab spacing) */
912 /* Set the high bit as a flag if num_chars is after a previous tab */
916 add_echo_byte(num_chars
, ldata
);
920 * echo_char_raw - echo a character raw
921 * @c: unicode byte to echo
922 * @tty: terminal device
924 * Echo user input back onto the screen. This must be called only when
925 * L_ECHO(tty) is true. Called from the driver receive_buf path.
927 * This variant does not treat control characters specially.
930 static void echo_char_raw(unsigned char c
, struct n_tty_data
*ldata
)
932 if (c
== ECHO_OP_START
) {
933 add_echo_byte(ECHO_OP_START
, ldata
);
934 add_echo_byte(ECHO_OP_START
, ldata
);
936 add_echo_byte(c
, ldata
);
941 * echo_char - echo a character
942 * @c: unicode byte to echo
943 * @tty: terminal device
945 * Echo user input back onto the screen. This must be called only when
946 * L_ECHO(tty) is true. Called from the driver receive_buf path.
948 * This variant tags control characters to be echoed as "^X"
949 * (where X is the letter representing the control char).
952 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
954 struct n_tty_data
*ldata
= tty
->disc_data
;
956 if (c
== ECHO_OP_START
) {
957 add_echo_byte(ECHO_OP_START
, ldata
);
958 add_echo_byte(ECHO_OP_START
, ldata
);
960 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
961 add_echo_byte(ECHO_OP_START
, ldata
);
962 add_echo_byte(c
, ldata
);
967 * finish_erasing - complete erase
971 static inline void finish_erasing(struct n_tty_data
*ldata
)
973 if (ldata
->erasing
) {
974 echo_char_raw('/', ldata
);
980 * eraser - handle erase function
981 * @c: character input
982 * @tty: terminal device
984 * Perform erase and necessary output when an erase character is
985 * present in the stream from the driver layer. Handles the complexities
986 * of UTF-8 multibyte symbols.
988 * n_tty_receive_buf()/producer path:
989 * caller holds non-exclusive termios_rwsem
992 * Modifying the read_head is not considered a publish in this context
993 * because canonical mode is active -- only canon_head publishes
996 static void eraser(unsigned char c
, struct tty_struct
*tty
)
998 struct n_tty_data
*ldata
= tty
->disc_data
;
999 enum { ERASE
, WERASE
, KILL
} kill_type
;
1004 if (ldata
->read_head
== ldata
->canon_head
) {
1005 /* process_output('\a', tty); */ /* what do you think? */
1008 if (c
== ERASE_CHAR(tty
))
1010 else if (c
== WERASE_CHAR(tty
))
1014 ldata
->read_head
= ldata
->canon_head
;
1017 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
1018 ldata
->read_head
= ldata
->canon_head
;
1019 finish_erasing(ldata
);
1020 echo_char(KILL_CHAR(tty
), tty
);
1021 /* Add a newline if ECHOK is on and ECHOKE is off. */
1023 echo_char_raw('\n', ldata
);
1030 while (ldata
->read_head
!= ldata
->canon_head
) {
1031 head
= ldata
->read_head
;
1033 /* erase a single possibly multibyte character */
1036 c
= read_buf(ldata
, head
);
1037 } while (is_continuation(c
, tty
) && head
!= ldata
->canon_head
);
1039 /* do not partially erase */
1040 if (is_continuation(c
, tty
))
1043 if (kill_type
== WERASE
) {
1044 /* Equivalent to BSD's ALTWERASE. */
1045 if (isalnum(c
) || c
== '_')
1047 else if (seen_alnums
)
1050 cnt
= ldata
->read_head
- head
;
1051 ldata
->read_head
= head
;
1053 if (L_ECHOPRT(tty
)) {
1054 if (!ldata
->erasing
) {
1055 echo_char_raw('\\', ldata
);
1058 /* if cnt > 1, output a multi-byte character */
1062 echo_char_raw(read_buf(ldata
, head
), ldata
);
1063 echo_move_back_col(ldata
);
1065 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
1066 echo_char(ERASE_CHAR(tty
), tty
);
1067 } else if (c
== '\t') {
1068 unsigned int num_chars
= 0;
1070 size_t tail
= ldata
->read_head
;
1073 * Count the columns used for characters
1074 * since the start of input or after a
1076 * This info is used to go back the correct
1077 * number of columns.
1079 while (tail
!= ldata
->canon_head
) {
1081 c
= read_buf(ldata
, tail
);
1085 } else if (iscntrl(c
)) {
1088 } else if (!is_continuation(c
, tty
)) {
1092 echo_erase_tab(num_chars
, after_tab
, ldata
);
1094 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
1095 echo_char_raw('\b', ldata
);
1096 echo_char_raw(' ', ldata
);
1097 echo_char_raw('\b', ldata
);
1099 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
1100 echo_char_raw('\b', ldata
);
1101 echo_char_raw(' ', ldata
);
1102 echo_char_raw('\b', ldata
);
1106 if (kill_type
== ERASE
)
1109 if (ldata
->read_head
== ldata
->canon_head
&& L_ECHO(tty
))
1110 finish_erasing(ldata
);
1114 * isig - handle the ISIG optio
1118 * Called when a signal is being sent due to terminal input.
1119 * Called from the driver receive_buf path so serialized.
1121 * Locking: ctrl_lock
1124 static void isig(int sig
, struct tty_struct
*tty
)
1126 struct pid
*tty_pgrp
= tty_get_pgrp(tty
);
1128 kill_pgrp(tty_pgrp
, sig
, 1);
1134 * n_tty_receive_break - handle break
1137 * An RS232 break event has been hit in the incoming bitstream. This
1138 * can cause a variety of events depending upon the termios settings.
1140 * n_tty_receive_buf()/producer path:
1141 * caller holds non-exclusive termios_rwsem
1142 * publishes read_head via put_tty_queue()
1144 * Note: may get exclusive termios_rwsem if flushing input buffer
1147 static void n_tty_receive_break(struct tty_struct
*tty
)
1149 struct n_tty_data
*ldata
= tty
->disc_data
;
1153 if (I_BRKINT(tty
)) {
1155 if (!L_NOFLSH(tty
)) {
1156 /* flushing needs exclusive termios_rwsem */
1157 up_read(&tty
->termios_rwsem
);
1158 n_tty_flush_buffer(tty
);
1159 tty_driver_flush_buffer(tty
);
1160 down_read(&tty
->termios_rwsem
);
1164 if (I_PARMRK(tty
)) {
1165 put_tty_queue('\377', ldata
);
1166 put_tty_queue('\0', ldata
);
1168 put_tty_queue('\0', ldata
);
1169 if (waitqueue_active(&tty
->read_wait
))
1170 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1174 * n_tty_receive_overrun - handle overrun reporting
1177 * Data arrived faster than we could process it. While the tty
1178 * driver has flagged this the bits that were missed are gone
1181 * Called from the receive_buf path so single threaded. Does not
1182 * need locking as num_overrun and overrun_time are function
1186 static void n_tty_receive_overrun(struct tty_struct
*tty
)
1188 struct n_tty_data
*ldata
= tty
->disc_data
;
1191 ldata
->num_overrun
++;
1192 if (time_after(jiffies
, ldata
->overrun_time
+ HZ
) ||
1193 time_after(ldata
->overrun_time
, jiffies
)) {
1194 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1196 ldata
->num_overrun
);
1197 ldata
->overrun_time
= jiffies
;
1198 ldata
->num_overrun
= 0;
1203 * n_tty_receive_parity_error - error notifier
1204 * @tty: terminal device
1207 * Process a parity error and queue the right data to indicate
1208 * the error case if necessary.
1210 * n_tty_receive_buf()/producer path:
1211 * caller holds non-exclusive termios_rwsem
1212 * publishes read_head via put_tty_queue()
1214 static void n_tty_receive_parity_error(struct tty_struct
*tty
, unsigned char c
)
1216 struct n_tty_data
*ldata
= tty
->disc_data
;
1221 if (I_PARMRK(tty
)) {
1222 put_tty_queue('\377', ldata
);
1223 put_tty_queue('\0', ldata
);
1224 put_tty_queue(c
, ldata
);
1226 put_tty_queue('\0', ldata
);
1228 put_tty_queue(c
, ldata
);
1229 if (waitqueue_active(&tty
->read_wait
))
1230 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1234 n_tty_receive_signal_char(struct tty_struct
*tty
, int signal
, unsigned char c
)
1236 if (!L_NOFLSH(tty
)) {
1237 /* flushing needs exclusive termios_rwsem */
1238 up_read(&tty
->termios_rwsem
);
1239 n_tty_flush_buffer(tty
);
1240 tty_driver_flush_buffer(tty
);
1241 down_read(&tty
->termios_rwsem
);
1249 process_echoes(tty
);
1255 * n_tty_receive_char - perform processing
1256 * @tty: terminal device
1259 * Process an individual character of input received from the driver.
1260 * This is serialized with respect to itself by the rules for the
1263 * n_tty_receive_buf()/producer path:
1264 * caller holds non-exclusive termios_rwsem
1265 * publishes canon_head if canonical mode is active
1266 * otherwise, publishes read_head via put_tty_queue()
1268 * Returns 1 if LNEXT was received, else returns 0
1272 n_tty_receive_char_special(struct tty_struct
*tty
, unsigned char c
)
1274 struct n_tty_data
*ldata
= tty
->disc_data
;
1277 if (c
== START_CHAR(tty
)) {
1279 process_echoes(tty
);
1282 if (c
== STOP_CHAR(tty
)) {
1289 if (c
== INTR_CHAR(tty
)) {
1290 n_tty_receive_signal_char(tty
, SIGINT
, c
);
1292 } else if (c
== QUIT_CHAR(tty
)) {
1293 n_tty_receive_signal_char(tty
, SIGQUIT
, c
);
1295 } else if (c
== SUSP_CHAR(tty
)) {
1296 n_tty_receive_signal_char(tty
, SIGTSTP
, c
);
1301 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1303 process_echoes(tty
);
1311 } else if (c
== '\n' && I_INLCR(tty
))
1314 if (ldata
->icanon
) {
1315 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1316 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1321 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1324 finish_erasing(ldata
);
1325 if (L_ECHOCTL(tty
)) {
1326 echo_char_raw('^', ldata
);
1327 echo_char_raw('\b', ldata
);
1333 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) && L_IEXTEN(tty
)) {
1334 size_t tail
= ldata
->canon_head
;
1336 finish_erasing(ldata
);
1338 echo_char_raw('\n', ldata
);
1339 while (tail
!= ldata
->read_head
) {
1340 echo_char(read_buf(ldata
, tail
), tty
);
1347 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1348 echo_char_raw('\n', ldata
);
1351 goto handle_newline
;
1353 if (c
== EOF_CHAR(tty
)) {
1354 c
= __DISABLED_CHAR
;
1355 goto handle_newline
;
1357 if ((c
== EOL_CHAR(tty
)) ||
1358 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1360 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1363 /* Record the column of first canon char. */
1364 if (ldata
->canon_head
== ldata
->read_head
)
1365 echo_set_canon_col(ldata
);
1370 * XXX does PARMRK doubling happen for
1371 * EOL_CHAR and EOL2_CHAR?
1373 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1374 put_tty_queue(c
, ldata
);
1377 set_bit(ldata
->read_head
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
);
1378 put_tty_queue(c
, ldata
);
1379 ldata
->canon_head
= ldata
->read_head
;
1380 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1381 if (waitqueue_active(&tty
->read_wait
))
1382 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1388 finish_erasing(ldata
);
1390 echo_char_raw('\n', ldata
);
1392 /* Record the column of first canon char. */
1393 if (ldata
->canon_head
== ldata
->read_head
)
1394 echo_set_canon_col(ldata
);
1400 /* PARMRK doubling check */
1401 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1402 put_tty_queue(c
, ldata
);
1404 put_tty_queue(c
, ldata
);
1409 n_tty_receive_char_inline(struct tty_struct
*tty
, unsigned char c
)
1411 struct n_tty_data
*ldata
= tty
->disc_data
;
1413 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1415 process_echoes(tty
);
1418 finish_erasing(ldata
);
1419 /* Record the column of first canon char. */
1420 if (ldata
->canon_head
== ldata
->read_head
)
1421 echo_set_canon_col(ldata
);
1425 /* PARMRK doubling check */
1426 if (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1427 put_tty_queue(c
, ldata
);
1428 put_tty_queue(c
, ldata
);
1431 static void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1433 n_tty_receive_char_inline(tty
, c
);
1437 n_tty_receive_char_fast(struct tty_struct
*tty
, unsigned char c
)
1439 struct n_tty_data
*ldata
= tty
->disc_data
;
1441 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) && I_IXANY(tty
)) {
1443 process_echoes(tty
);
1446 finish_erasing(ldata
);
1447 /* Record the column of first canon char. */
1448 if (ldata
->canon_head
== ldata
->read_head
)
1449 echo_set_canon_col(ldata
);
1453 put_tty_queue(c
, ldata
);
1456 static void n_tty_receive_char_closing(struct tty_struct
*tty
, unsigned char c
)
1460 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1464 if (c
== STOP_CHAR(tty
))
1466 else if (c
== START_CHAR(tty
) ||
1467 (tty
->stopped
&& !tty
->flow_stopped
&& I_IXANY(tty
) &&
1468 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) &&
1469 c
!= SUSP_CHAR(tty
))) {
1471 process_echoes(tty
);
1477 n_tty_receive_char_flagged(struct tty_struct
*tty
, unsigned char c
, char flag
)
1483 n_tty_receive_break(tty
);
1487 n_tty_receive_parity_error(tty
, c
);
1490 n_tty_receive_overrun(tty
);
1493 printk(KERN_ERR
"%s: unknown flag %d\n",
1494 tty_name(tty
, buf
), flag
);
1500 n_tty_receive_char_lnext(struct tty_struct
*tty
, unsigned char c
, char flag
)
1502 struct n_tty_data
*ldata
= tty
->disc_data
;
1505 if (likely(flag
== TTY_NORMAL
)) {
1508 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1510 n_tty_receive_char(tty
, c
);
1512 n_tty_receive_char_flagged(tty
, c
, flag
);
1516 * n_tty_receive_buf - data receive
1517 * @tty: terminal device
1520 * @count: characters
1522 * Called by the terminal driver when a block of characters has
1523 * been received. This function must be called from soft contexts
1524 * not from interrupt context. The driver is responsible for making
1525 * calls one at a time and in order (or using flush_to_ldisc)
1527 * n_tty_receive_buf()/producer path:
1528 * claims non-exclusive termios_rwsem
1529 * publishes read_head and canon_head
1533 n_tty_receive_buf_real_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1534 char *fp
, int count
)
1536 struct n_tty_data
*ldata
= tty
->disc_data
;
1539 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1540 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1541 n
= min_t(size_t, count
, n
);
1542 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1543 ldata
->read_head
+= n
;
1547 head
= ldata
->read_head
& (N_TTY_BUF_SIZE
- 1);
1548 n
= N_TTY_BUF_SIZE
- max(read_cnt(ldata
), head
);
1549 n
= min_t(size_t, count
, n
);
1550 memcpy(read_buf_addr(ldata
, head
), cp
, n
);
1551 ldata
->read_head
+= n
;
1555 n_tty_receive_buf_raw(struct tty_struct
*tty
, const unsigned char *cp
,
1556 char *fp
, int count
)
1558 struct n_tty_data
*ldata
= tty
->disc_data
;
1559 char flag
= TTY_NORMAL
;
1564 if (likely(flag
== TTY_NORMAL
))
1565 put_tty_queue(*cp
++, ldata
);
1567 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1572 n_tty_receive_buf_closing(struct tty_struct
*tty
, const unsigned char *cp
,
1573 char *fp
, int count
)
1575 char flag
= TTY_NORMAL
;
1580 if (likely(flag
== TTY_NORMAL
))
1581 n_tty_receive_char_closing(tty
, *cp
++);
1583 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1588 n_tty_receive_buf_standard(struct tty_struct
*tty
, const unsigned char *cp
,
1589 char *fp
, int count
)
1591 struct n_tty_data
*ldata
= tty
->disc_data
;
1592 char flag
= TTY_NORMAL
;
1597 if (likely(flag
== TTY_NORMAL
)) {
1598 unsigned char c
= *cp
++;
1602 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1604 if (L_EXTPROC(tty
)) {
1605 put_tty_queue(c
, ldata
);
1608 if (!test_bit(c
, ldata
->char_map
))
1609 n_tty_receive_char_inline(tty
, c
);
1610 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1613 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1617 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1622 n_tty_receive_buf_fast(struct tty_struct
*tty
, const unsigned char *cp
,
1623 char *fp
, int count
)
1625 struct n_tty_data
*ldata
= tty
->disc_data
;
1626 char flag
= TTY_NORMAL
;
1631 if (likely(flag
== TTY_NORMAL
)) {
1632 unsigned char c
= *cp
++;
1634 if (!test_bit(c
, ldata
->char_map
))
1635 n_tty_receive_char_fast(tty
, c
);
1636 else if (n_tty_receive_char_special(tty
, c
) && count
) {
1639 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1643 n_tty_receive_char_flagged(tty
, *cp
++, flag
);
1647 static void __receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1648 char *fp
, int count
)
1650 struct n_tty_data
*ldata
= tty
->disc_data
;
1651 bool preops
= I_ISTRIP(tty
) || (I_IUCLC(tty
) && L_IEXTEN(tty
));
1653 if (ldata
->real_raw
)
1654 n_tty_receive_buf_real_raw(tty
, cp
, fp
, count
);
1655 else if (ldata
->raw
|| (L_EXTPROC(tty
) && !preops
))
1656 n_tty_receive_buf_raw(tty
, cp
, fp
, count
);
1657 else if (tty
->closing
&& !L_EXTPROC(tty
))
1658 n_tty_receive_buf_closing(tty
, cp
, fp
, count
);
1661 char flag
= TTY_NORMAL
;
1665 n_tty_receive_char_lnext(tty
, *cp
++, flag
);
1669 if (!preops
&& !I_PARMRK(tty
))
1670 n_tty_receive_buf_fast(tty
, cp
, fp
, count
);
1672 n_tty_receive_buf_standard(tty
, cp
, fp
, count
);
1675 if (tty
->ops
->flush_chars
)
1676 tty
->ops
->flush_chars(tty
);
1679 if ((!ldata
->icanon
&& (read_cnt(ldata
) >= ldata
->minimum_to_wake
)) ||
1681 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1682 if (waitqueue_active(&tty
->read_wait
))
1683 wake_up_interruptible_poll(&tty
->read_wait
, POLLIN
);
1688 n_tty_receive_buf_common(struct tty_struct
*tty
, const unsigned char *cp
,
1689 char *fp
, int count
, int flow
)
1691 struct n_tty_data
*ldata
= tty
->disc_data
;
1692 int room
, n
, rcvd
= 0;
1694 down_read(&tty
->termios_rwsem
);
1697 room
= receive_room(tty
);
1698 n
= min(count
, room
);
1704 __receive_buf(tty
, cp
, fp
, n
);
1712 tty
->receive_room
= room
;
1713 n_tty_check_throttle(tty
);
1714 up_read(&tty
->termios_rwsem
);
1719 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1720 char *fp
, int count
)
1722 n_tty_receive_buf_common(tty
, cp
, fp
, count
, 0);
1725 static int n_tty_receive_buf2(struct tty_struct
*tty
, const unsigned char *cp
,
1726 char *fp
, int count
)
1728 return n_tty_receive_buf_common(tty
, cp
, fp
, count
, 1);
1731 int is_ignored(int sig
)
1733 return (sigismember(¤t
->blocked
, sig
) ||
1734 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1738 * n_tty_set_termios - termios data changed
1740 * @old: previous data
1742 * Called by the tty layer when the user changes termios flags so
1743 * that the line discipline can plan ahead. This function cannot sleep
1744 * and is protected from re-entry by the tty layer. The user is
1745 * guaranteed that this function will not be re-entered or in progress
1746 * when the ldisc is closed.
1748 * Locking: Caller holds tty->termios_rwsem
1751 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1753 struct n_tty_data
*ldata
= tty
->disc_data
;
1755 if (!old
|| (old
->c_lflag
^ tty
->termios
.c_lflag
) & ICANON
) {
1756 bitmap_zero(ldata
->read_flags
, N_TTY_BUF_SIZE
);
1757 ldata
->line_start
= ldata
->read_tail
;
1758 if (!L_ICANON(tty
) || !read_cnt(ldata
)) {
1759 ldata
->canon_head
= ldata
->read_tail
;
1762 set_bit((ldata
->read_head
- 1) & (N_TTY_BUF_SIZE
- 1),
1764 ldata
->canon_head
= ldata
->read_head
;
1771 ldata
->icanon
= (L_ICANON(tty
) != 0);
1773 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1774 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1775 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1777 bitmap_zero(ldata
->char_map
, 256);
1779 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1780 set_bit('\r', ldata
->char_map
);
1782 set_bit('\n', ldata
->char_map
);
1784 if (L_ICANON(tty
)) {
1785 set_bit(ERASE_CHAR(tty
), ldata
->char_map
);
1786 set_bit(KILL_CHAR(tty
), ldata
->char_map
);
1787 set_bit(EOF_CHAR(tty
), ldata
->char_map
);
1788 set_bit('\n', ldata
->char_map
);
1789 set_bit(EOL_CHAR(tty
), ldata
->char_map
);
1790 if (L_IEXTEN(tty
)) {
1791 set_bit(WERASE_CHAR(tty
), ldata
->char_map
);
1792 set_bit(LNEXT_CHAR(tty
), ldata
->char_map
);
1793 set_bit(EOL2_CHAR(tty
), ldata
->char_map
);
1795 set_bit(REPRINT_CHAR(tty
),
1800 set_bit(START_CHAR(tty
), ldata
->char_map
);
1801 set_bit(STOP_CHAR(tty
), ldata
->char_map
);
1804 set_bit(INTR_CHAR(tty
), ldata
->char_map
);
1805 set_bit(QUIT_CHAR(tty
), ldata
->char_map
);
1806 set_bit(SUSP_CHAR(tty
), ldata
->char_map
);
1808 clear_bit(__DISABLED_CHAR
, ldata
->char_map
);
1810 ldata
->real_raw
= 0;
1813 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1814 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1815 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1816 ldata
->real_raw
= 1;
1818 ldata
->real_raw
= 0;
1820 n_tty_set_room(tty
);
1822 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1823 * been stopped by STOP_CHAR(tty) before it.
1825 if (!I_IXON(tty
) && old
&& (old
->c_iflag
& IXON
) && !tty
->flow_stopped
) {
1827 process_echoes(tty
);
1830 /* The termios change make the tty ready for I/O */
1831 if (waitqueue_active(&tty
->write_wait
))
1832 wake_up_interruptible(&tty
->write_wait
);
1833 if (waitqueue_active(&tty
->read_wait
))
1834 wake_up_interruptible(&tty
->read_wait
);
1838 * n_tty_close - close the ldisc for this tty
1841 * Called from the terminal layer when this line discipline is
1842 * being shut down, either because of a close or becsuse of a
1843 * discipline change. The function will not be called while other
1844 * ldisc methods are in progress.
1847 static void n_tty_close(struct tty_struct
*tty
)
1849 struct n_tty_data
*ldata
= tty
->disc_data
;
1852 n_tty_packet_mode_flush(tty
);
1855 tty
->disc_data
= NULL
;
1859 * n_tty_open - open an ldisc
1860 * @tty: terminal to open
1862 * Called when this line discipline is being attached to the
1863 * terminal device. Can sleep. Called serialized so that no
1864 * other events will occur in parallel. No further open will occur
1868 static int n_tty_open(struct tty_struct
*tty
)
1870 struct n_tty_data
*ldata
;
1872 /* Currently a malloc failure here can panic */
1873 ldata
= vmalloc(sizeof(*ldata
));
1877 ldata
->overrun_time
= jiffies
;
1878 mutex_init(&ldata
->atomic_read_lock
);
1879 mutex_init(&ldata
->output_lock
);
1881 tty
->disc_data
= ldata
;
1882 reset_buffer_flags(tty
->disc_data
);
1884 ldata
->canon_column
= 0;
1885 ldata
->minimum_to_wake
= 1;
1886 ldata
->num_overrun
= 0;
1890 /* indicate buffer work may resume */
1891 clear_bit(TTY_LDISC_HALTED
, &tty
->flags
);
1892 n_tty_set_termios(tty
, NULL
);
1893 tty_unthrottle(tty
);
1900 static inline int input_available_p(struct tty_struct
*tty
, int poll
)
1902 struct n_tty_data
*ldata
= tty
->disc_data
;
1903 int amt
= poll
&& !TIME_CHAR(tty
) && MIN_CHAR(tty
) ? MIN_CHAR(tty
) : 1;
1905 if (ldata
->icanon
&& !L_EXTPROC(tty
))
1906 return ldata
->canon_head
!= ldata
->read_tail
;
1908 return read_cnt(ldata
) >= amt
;
1912 * copy_from_read_buf - copy read data directly
1913 * @tty: terminal device
1917 * Helper function to speed up n_tty_read. It is only called when
1918 * ICANON is off; it copies characters straight from the tty queue to
1919 * user space directly. It can be profitably called twice; once to
1920 * drain the space from the tail pointer to the (physical) end of the
1921 * buffer, and once to drain the space from the (physical) beginning of
1922 * the buffer to head pointer.
1924 * Called under the ldata->atomic_read_lock sem
1926 * n_tty_read()/consumer path:
1927 * caller holds non-exclusive termios_rwsem
1928 * read_tail published
1931 static int copy_from_read_buf(struct tty_struct
*tty
,
1932 unsigned char __user
**b
,
1936 struct n_tty_data
*ldata
= tty
->disc_data
;
1940 size_t tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
1943 n
= min(read_cnt(ldata
), N_TTY_BUF_SIZE
- tail
);
1946 retval
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
1948 is_eof
= n
== 1 && read_buf(ldata
, tail
) == EOF_CHAR(tty
);
1949 tty_audit_add_data(tty
, read_buf_addr(ldata
, tail
), n
,
1951 ldata
->read_tail
+= n
;
1952 /* Turn single EOF into zero-length read */
1953 if (L_EXTPROC(tty
) && ldata
->icanon
&& is_eof
&& !read_cnt(ldata
))
1962 * canon_copy_from_read_buf - copy read data in canonical mode
1963 * @tty: terminal device
1967 * Helper function for n_tty_read. It is only called when ICANON is on;
1968 * it copies one line of input up to and including the line-delimiting
1969 * character into the user-space buffer.
1971 * NB: When termios is changed from non-canonical to canonical mode and
1972 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1973 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1974 * This causes data already processed as input to be immediately available
1975 * as input although a newline has not been received.
1977 * Called under the atomic_read_lock mutex
1979 * n_tty_read()/consumer path:
1980 * caller holds non-exclusive termios_rwsem
1981 * read_tail published
1984 static int canon_copy_from_read_buf(struct tty_struct
*tty
,
1985 unsigned char __user
**b
,
1988 struct n_tty_data
*ldata
= tty
->disc_data
;
1989 size_t n
, size
, more
, c
;
1995 /* N.B. avoid overrun if nr == 0 */
1996 n
= min(*nr
, read_cnt(ldata
));
2000 tail
= ldata
->read_tail
& (N_TTY_BUF_SIZE
- 1);
2001 size
= min_t(size_t, tail
+ n
, N_TTY_BUF_SIZE
);
2003 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2004 __func__
, *nr
, tail
, n
, size
);
2006 eol
= find_next_bit(ldata
->read_flags
, size
, tail
);
2007 more
= n
- (size
- tail
);
2008 if (eol
== N_TTY_BUF_SIZE
&& more
) {
2009 /* scan wrapped without finding set bit */
2010 eol
= find_next_bit(ldata
->read_flags
, more
, 0);
2013 } else if (eol
!= size
)
2016 size
= N_TTY_BUF_SIZE
- tail
;
2023 if (found
&& !ldata
->push
&& read_buf(ldata
, eol
) == __DISABLED_CHAR
) {
2025 eof_push
= !n
&& ldata
->read_tail
!= ldata
->line_start
;
2028 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2029 __func__
, eol
, found
, n
, c
, size
, more
);
2032 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), size
);
2035 ret
= copy_to_user(*b
+ size
, ldata
->read_buf
, n
- size
);
2037 ret
= copy_to_user(*b
, read_buf_addr(ldata
, tail
), n
);
2045 clear_bit(eol
, ldata
->read_flags
);
2046 smp_mb__after_atomic();
2047 ldata
->read_tail
+= c
;
2051 ldata
->line_start
= ldata
->read_tail
;
2054 tty_audit_push(tty
);
2056 return eof_push
? -EAGAIN
: 0;
2059 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
2063 * job_control - check job control
2065 * @file: file handle
2067 * Perform job control management checks on this file/tty descriptor
2068 * and if appropriate send any needed signals and return a negative
2069 * error code if action should be taken.
2071 * Locking: redirected write test is safe
2072 * current->signal->tty check is safe
2073 * ctrl_lock to safely reference tty->pgrp
2076 static int job_control(struct tty_struct
*tty
, struct file
*file
)
2078 /* Job control check -- must be done at start and after
2079 every sleep (POSIX.1 7.1.1.4). */
2080 /* NOTE: not yet done after every sleep pending a thorough
2081 check of the logic of this change. -- jlc */
2082 /* don't stop on /dev/console */
2083 if (file
->f_op
->write
== redirected_tty_write
||
2084 current
->signal
->tty
!= tty
)
2087 spin_lock_irq(&tty
->ctrl_lock
);
2089 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
2090 else if (task_pgrp(current
) != tty
->pgrp
) {
2091 spin_unlock_irq(&tty
->ctrl_lock
);
2092 if (is_ignored(SIGTTIN
) || is_current_pgrp_orphaned())
2094 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
2095 set_thread_flag(TIF_SIGPENDING
);
2096 return -ERESTARTSYS
;
2098 spin_unlock_irq(&tty
->ctrl_lock
);
2104 * n_tty_read - read function for tty
2106 * @file: file object
2107 * @buf: userspace buffer pointer
2110 * Perform reads for the line discipline. We are guaranteed that the
2111 * line discipline will not be closed under us but we may get multiple
2112 * parallel readers and must handle this ourselves. We may also get
2113 * a hangup. Always called in user context, may sleep.
2115 * This code must be sure never to sleep through a hangup.
2117 * n_tty_read()/consumer path:
2118 * claims non-exclusive termios_rwsem
2119 * publishes read_tail
2122 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
2123 unsigned char __user
*buf
, size_t nr
)
2125 struct n_tty_data
*ldata
= tty
->disc_data
;
2126 unsigned char __user
*b
= buf
;
2127 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
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_irq(&tty
->link
->ctrl_lock
);
2178 cs
= tty
->link
->ctrl_status
;
2179 tty
->link
->ctrl_status
= 0;
2180 spin_unlock_irq(&tty
->link
->ctrl_lock
);
2181 if (tty_put_user(tty
, cs
, b
++)) {
2190 if (((minimum
- (b
- buf
)) < ldata
->minimum_to_wake
) &&
2191 ((minimum
- (b
- buf
)) >= 1))
2192 ldata
->minimum_to_wake
= (minimum
- (b
- buf
));
2194 if (!input_available_p(tty
, 0)) {
2195 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
2199 if (tty_hung_up_p(file
))
2203 if (file
->f_flags
& O_NONBLOCK
) {
2207 if (signal_pending(current
)) {
2208 retval
= -ERESTARTSYS
;
2211 n_tty_set_room(tty
);
2212 up_read(&tty
->termios_rwsem
);
2214 timeout
= wait_woken(&wait
, TASK_INTERRUPTIBLE
,
2217 down_read(&tty
->termios_rwsem
);
2221 if (ldata
->icanon
&& !L_EXTPROC(tty
)) {
2222 retval
= canon_copy_from_read_buf(tty
, &b
, &nr
);
2223 if (retval
== -EAGAIN
) {
2231 /* Deal with packet mode. */
2232 if (packet
&& b
== buf
) {
2233 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
2241 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
2242 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
2249 n_tty_check_unthrottle(tty
);
2251 if (b
- buf
>= minimum
)
2256 n_tty_set_room(tty
);
2257 up_read(&tty
->termios_rwsem
);
2259 remove_wait_queue(&tty
->read_wait
, &wait
);
2260 if (!waitqueue_active(&tty
->read_wait
))
2261 ldata
->minimum_to_wake
= minimum
;
2263 mutex_unlock(&ldata
->atomic_read_lock
);
2272 * n_tty_write - write function for tty
2274 * @file: file object
2275 * @buf: userspace buffer pointer
2278 * Write function of the terminal device. This is serialized with
2279 * respect to other write callers but not to termios changes, reads
2280 * and other such events. Since the receive code will echo characters,
2281 * thus calling driver write methods, the output_lock is used in
2282 * the output processing functions called here as well as in the
2283 * echo processing function to protect the column state and space
2284 * left in the buffer.
2286 * This code must be sure never to sleep through a hangup.
2288 * Locking: output_lock to protect column state and space left
2289 * (note that the process_output*() functions take this
2293 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
2294 const unsigned char *buf
, size_t nr
)
2296 const unsigned char *b
= buf
;
2297 DEFINE_WAIT_FUNC(wait
, woken_wake_function
);
2301 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2302 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
2303 retval
= tty_check_change(tty
);
2308 down_read(&tty
->termios_rwsem
);
2310 /* Write out any echoed characters that are still pending */
2311 process_echoes(tty
);
2313 add_wait_queue(&tty
->write_wait
, &wait
);
2315 if (signal_pending(current
)) {
2316 retval
= -ERESTARTSYS
;
2319 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
2325 ssize_t num
= process_output_block(tty
, b
, nr
);
2337 if (process_output(c
, tty
) < 0)
2341 if (tty
->ops
->flush_chars
)
2342 tty
->ops
->flush_chars(tty
);
2344 struct n_tty_data
*ldata
= tty
->disc_data
;
2347 mutex_lock(&ldata
->output_lock
);
2348 c
= tty
->ops
->write(tty
, b
, nr
);
2349 mutex_unlock(&ldata
->output_lock
);
2362 if (file
->f_flags
& O_NONBLOCK
) {
2366 up_read(&tty
->termios_rwsem
);
2368 wait_woken(&wait
, TASK_INTERRUPTIBLE
, MAX_SCHEDULE_TIMEOUT
);
2370 down_read(&tty
->termios_rwsem
);
2373 remove_wait_queue(&tty
->write_wait
, &wait
);
2374 if (b
- buf
!= nr
&& tty
->fasync
)
2375 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
2376 up_read(&tty
->termios_rwsem
);
2377 return (b
- buf
) ? b
- buf
: retval
;
2381 * n_tty_poll - poll method for N_TTY
2382 * @tty: terminal device
2383 * @file: file accessing it
2386 * Called when the line discipline is asked to poll() for data or
2387 * for special events. This code is not serialized with respect to
2388 * other events save open/close.
2390 * This code must be sure never to sleep through a hangup.
2391 * Called without the kernel lock held - fine
2394 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2397 struct n_tty_data
*ldata
= tty
->disc_data
;
2398 unsigned int mask
= 0;
2400 poll_wait(file
, &tty
->read_wait
, wait
);
2401 poll_wait(file
, &tty
->write_wait
, wait
);
2402 if (input_available_p(tty
, 1))
2403 mask
|= POLLIN
| POLLRDNORM
;
2404 if (tty
->packet
&& tty
->link
->ctrl_status
)
2405 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2406 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2408 if (tty_hung_up_p(file
))
2410 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2411 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2412 ldata
->minimum_to_wake
= MIN_CHAR(tty
);
2414 ldata
->minimum_to_wake
= 1;
2416 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2417 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2418 tty_write_room(tty
) > 0)
2419 mask
|= POLLOUT
| POLLWRNORM
;
2423 static unsigned long inq_canon(struct n_tty_data
*ldata
)
2425 size_t nr
, head
, tail
;
2427 if (ldata
->canon_head
== ldata
->read_tail
)
2429 head
= ldata
->canon_head
;
2430 tail
= ldata
->read_tail
;
2432 /* Skip EOF-chars.. */
2433 while (head
!= tail
) {
2434 if (test_bit(tail
& (N_TTY_BUF_SIZE
- 1), ldata
->read_flags
) &&
2435 read_buf(ldata
, tail
) == __DISABLED_CHAR
)
2442 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2443 unsigned int cmd
, unsigned long arg
)
2445 struct n_tty_data
*ldata
= tty
->disc_data
;
2450 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2452 down_write(&tty
->termios_rwsem
);
2454 retval
= inq_canon(ldata
);
2456 retval
= read_cnt(ldata
);
2457 up_write(&tty
->termios_rwsem
);
2458 return put_user(retval
, (unsigned int __user
*) arg
);
2460 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2464 static void n_tty_fasync(struct tty_struct
*tty
, int on
)
2466 struct n_tty_data
*ldata
= tty
->disc_data
;
2468 if (!waitqueue_active(&tty
->read_wait
)) {
2470 ldata
->minimum_to_wake
= 1;
2471 else if (!tty
->fasync
)
2472 ldata
->minimum_to_wake
= N_TTY_BUF_SIZE
;
2476 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2477 .magic
= TTY_LDISC_MAGIC
,
2480 .close
= n_tty_close
,
2481 .flush_buffer
= n_tty_flush_buffer
,
2482 .chars_in_buffer
= n_tty_chars_in_buffer
,
2484 .write
= n_tty_write
,
2485 .ioctl
= n_tty_ioctl
,
2486 .set_termios
= n_tty_set_termios
,
2488 .receive_buf
= n_tty_receive_buf
,
2489 .write_wakeup
= n_tty_write_wakeup
,
2490 .fasync
= n_tty_fasync
,
2491 .receive_buf2
= n_tty_receive_buf2
,
2495 * n_tty_inherit_ops - inherit N_TTY methods
2496 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2498 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2502 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2504 *ops
= tty_ldisc_N_TTY
;
2506 ops
->refcount
= ops
->flags
= 0;
2508 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);