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>
53 #include <asm/system.h>
55 /* number of characters left in xmit buffer before select has we have room */
56 #define WAKEUP_CHARS 256
59 * This defines the low- and high-watermarks for throttling and
60 * unthrottling the TTY driver. These watermarks are used for
61 * controlling the space in the read buffer.
63 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
64 #define TTY_THRESHOLD_UNTHROTTLE 128
67 * Special byte codes used in the echo buffer to represent operations
68 * or special handling of characters. Bytes in the echo buffer that
69 * are not part of such special blocks are treated as normal character
72 #define ECHO_OP_START 0xff
73 #define ECHO_OP_MOVE_BACK_COL 0x80
74 #define ECHO_OP_SET_CANON_COL 0x81
75 #define ECHO_OP_ERASE_TAB 0x82
77 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
78 unsigned char __user
*ptr
)
80 tty_audit_add_data(tty
, &x
, 1);
81 return put_user(x
, ptr
);
85 * n_tty_set__room - receive space
88 * Called by the driver to find out how much data it is
89 * permitted to feed to the line discipline without any being lost
90 * and thus to manage flow control. Not serialized. Answers for the
94 static void n_tty_set_room(struct tty_struct
*tty
)
96 /* tty->read_cnt is not read locked ? */
97 int left
= N_TTY_BUF_SIZE
- tty
->read_cnt
- 1;
100 * If we are doing input canonicalization, and there are no
101 * pending newlines, let characters through without limit, so
102 * that erase characters will be handled. Other excess
103 * characters will be beeped.
106 left
= tty
->icanon
&& !tty
->canon_data
;
107 tty
->receive_room
= left
;
110 static void put_tty_queue_nolock(unsigned char c
, struct tty_struct
*tty
)
112 if (tty
->read_cnt
< N_TTY_BUF_SIZE
) {
113 tty
->read_buf
[tty
->read_head
] = c
;
114 tty
->read_head
= (tty
->read_head
+ 1) & (N_TTY_BUF_SIZE
-1);
120 * put_tty_queue - add character to tty
124 * Add a character to the tty read_buf queue. This is done under the
125 * read_lock to serialize character addition and also to protect us
126 * against parallel reads or flushes
129 static void put_tty_queue(unsigned char c
, struct tty_struct
*tty
)
133 * The problem of stomping on the buffers ends here.
134 * Why didn't anyone see this one coming? --AJK
136 spin_lock_irqsave(&tty
->read_lock
, flags
);
137 put_tty_queue_nolock(c
, tty
);
138 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
142 * check_unthrottle - allow new receive data
145 * Check whether to call the driver unthrottle functions
147 * Can sleep, may be called under the atomic_read_lock mutex but
148 * this is not guaranteed.
150 static void check_unthrottle(struct tty_struct
*tty
)
157 * reset_buffer_flags - reset buffer state
158 * @tty: terminal to reset
160 * Reset the read buffer counters, clear the flags,
161 * and make sure the driver is unthrottled. Called
162 * from n_tty_open() and n_tty_flush_buffer().
164 * Locking: tty_read_lock for read fields.
167 static void reset_buffer_flags(struct tty_struct
*tty
)
171 spin_lock_irqsave(&tty
->read_lock
, flags
);
172 tty
->read_head
= tty
->read_tail
= tty
->read_cnt
= 0;
173 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
175 mutex_lock(&tty
->echo_lock
);
176 tty
->echo_pos
= tty
->echo_cnt
= tty
->echo_overrun
= 0;
177 mutex_unlock(&tty
->echo_lock
);
179 tty
->canon_head
= tty
->canon_data
= tty
->erasing
= 0;
180 memset(&tty
->read_flags
, 0, sizeof tty
->read_flags
);
182 check_unthrottle(tty
);
186 * n_tty_flush_buffer - clean input queue
187 * @tty: terminal device
189 * Flush the input buffer. Called when the line discipline is
190 * being closed, when the tty layer wants the buffer flushed (eg
191 * at hangup) or when the N_TTY line discipline internally has to
192 * clean the pending queue (for example some signals).
194 * Locking: ctrl_lock, read_lock.
197 static void n_tty_flush_buffer(struct tty_struct
*tty
)
200 /* clear everything and unthrottle the driver */
201 reset_buffer_flags(tty
);
206 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
207 if (tty
->link
->packet
) {
208 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
209 wake_up_interruptible(&tty
->link
->read_wait
);
211 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
215 * n_tty_chars_in_buffer - report available bytes
218 * Report the number of characters buffered to be delivered to user
219 * at this instant in time.
224 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
229 spin_lock_irqsave(&tty
->read_lock
, flags
);
232 } else if (tty
->canon_data
) {
233 n
= (tty
->canon_head
> tty
->read_tail
) ?
234 tty
->canon_head
- tty
->read_tail
:
235 tty
->canon_head
+ (N_TTY_BUF_SIZE
- tty
->read_tail
);
237 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
242 * is_utf8_continuation - utf8 multibyte check
245 * Returns true if the utf8 character 'c' is a multibyte continuation
246 * character. We use this to correctly compute the on screen size
247 * of the character when printing
250 static inline int is_utf8_continuation(unsigned char c
)
252 return (c
& 0xc0) == 0x80;
256 * is_continuation - multibyte check
259 * Returns true if the utf8 character 'c' is a multibyte continuation
260 * character and the terminal is in unicode mode.
263 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
265 return I_IUTF8(tty
) && is_utf8_continuation(c
);
269 * do_output_char - output one character
270 * @c: character (or partial unicode symbol)
271 * @tty: terminal device
272 * @space: space available in tty driver write buffer
274 * This is a helper function that handles one output character
275 * (including special characters like TAB, CR, LF, etc.),
276 * doing OPOST processing and putting the results in the
277 * tty driver's write buffer.
279 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
280 * and NLDLY. They simply aren't relevant in the world today.
281 * If you ever need them, add them here.
283 * Returns the number of bytes of buffer space used or -1 if
286 * Locking: should be called under the output_lock to protect
287 * the column state and space left in the buffer
290 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
304 tty
->canon_column
= tty
->column
= 0;
305 tty
->ops
->write(tty
, "\r\n", 2);
308 tty
->canon_column
= tty
->column
;
311 if (O_ONOCR(tty
) && tty
->column
== 0)
316 tty
->canon_column
= tty
->column
= 0;
319 tty
->canon_column
= tty
->column
= 0;
322 spaces
= 8 - (tty
->column
& 7);
323 if (O_TABDLY(tty
) == XTABS
) {
326 tty
->column
+= spaces
;
327 tty
->ops
->write(tty
, " ", spaces
);
330 tty
->column
+= spaces
;
340 if (!is_continuation(c
, tty
))
346 tty_put_char(tty
, c
);
351 * process_output - output post processor
352 * @c: character (or partial unicode symbol)
353 * @tty: terminal device
355 * Output one character with OPOST processing.
356 * Returns -1 when the output device is full and the character
359 * Locking: output_lock to protect column state and space left
360 * (also, this is called from n_tty_write under the
361 * tty layer write lock)
364 static int process_output(unsigned char c
, struct tty_struct
*tty
)
368 mutex_lock(&tty
->output_lock
);
370 space
= tty_write_room(tty
);
371 retval
= do_output_char(c
, tty
, space
);
373 mutex_unlock(&tty
->output_lock
);
381 * process_output_block - block post processor
382 * @tty: terminal device
383 * @buf: character buffer
384 * @nr: number of bytes to output
386 * Output a block of characters with OPOST processing.
387 * Returns the number of characters output.
389 * This path is used to speed up block console writes, among other
390 * things when processing blocks of output data. It handles only
391 * the simple cases normally found and helps to generate blocks of
392 * symbols for the console driver and thus improve performance.
394 * Locking: output_lock to protect column state and space left
395 * (also, this is called from n_tty_write under the
396 * tty layer write lock)
399 static ssize_t
process_output_block(struct tty_struct
*tty
,
400 const unsigned char *buf
, unsigned int nr
)
404 const unsigned char *cp
;
406 mutex_lock(&tty
->output_lock
);
408 space
= tty_write_room(tty
);
410 mutex_unlock(&tty
->output_lock
);
416 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
417 unsigned char c
= *cp
;
425 tty
->canon_column
= tty
->column
;
428 if (O_ONOCR(tty
) && tty
->column
== 0)
432 tty
->canon_column
= tty
->column
= 0;
444 if (!is_continuation(c
, tty
))
451 i
= tty
->ops
->write(tty
, buf
, i
);
453 mutex_unlock(&tty
->output_lock
);
458 * process_echoes - write pending echo characters
459 * @tty: terminal device
461 * Write previously buffered echo (and other ldisc-generated)
462 * characters to the tty.
464 * Characters generated by the ldisc (including echoes) need to
465 * be buffered because the driver's write buffer can fill during
466 * heavy program output. Echoing straight to the driver will
467 * often fail under these conditions, causing lost characters and
468 * resulting mismatches of ldisc state information.
470 * Since the ldisc state must represent the characters actually sent
471 * to the driver at the time of the write, operations like certain
472 * changes in column state are also saved in the buffer and executed
475 * A circular fifo buffer is used so that the most recent characters
476 * are prioritized. Also, when control characters are echoed with a
477 * prefixed "^", the pair is treated atomically and thus not separated.
479 * Locking: output_lock to protect column state and space left,
480 * echo_lock to protect the echo buffer
483 static void process_echoes(struct tty_struct
*tty
)
487 unsigned char *cp
, *buf_end
;
492 mutex_lock(&tty
->output_lock
);
493 mutex_lock(&tty
->echo_lock
);
495 space
= tty_write_room(tty
);
497 buf_end
= tty
->echo_buf
+ N_TTY_BUF_SIZE
;
498 cp
= tty
->echo_buf
+ tty
->echo_pos
;
502 if (c
== ECHO_OP_START
) {
505 int no_space_left
= 0;
508 * If the buffer byte is the start of a multi-byte
509 * operation, get the next byte, which is either the
510 * op code or a control character value.
514 opp
-= N_TTY_BUF_SIZE
;
518 unsigned int num_chars
, num_bs
;
520 case ECHO_OP_ERASE_TAB
:
521 if (++opp
== buf_end
)
522 opp
-= N_TTY_BUF_SIZE
;
526 * Determine how many columns to go back
527 * in order to erase the tab.
528 * This depends on the number of columns
529 * used by other characters within the tab
530 * area. If this (modulo 8) count is from
531 * the start of input rather than from a
532 * previous tab, we offset by canon column.
533 * Otherwise, tab spacing is normal.
535 if (!(num_chars
& 0x80))
536 num_chars
+= tty
->canon_column
;
537 num_bs
= 8 - (num_chars
& 7);
539 if (num_bs
> space
) {
545 tty_put_char(tty
, '\b');
553 case ECHO_OP_SET_CANON_COL
:
554 tty
->canon_column
= tty
->column
;
559 case ECHO_OP_MOVE_BACK_COL
:
567 /* This is an escaped echo op start code */
572 tty_put_char(tty
, ECHO_OP_START
);
581 * If the op is not a special byte code,
582 * it is a ctrl char tagged to be echoed
583 * as "^X" (where X is the letter
584 * representing the control char).
585 * Note that we must ensure there is
586 * enough space for the whole ctrl pair.
593 tty_put_char(tty
, '^');
594 tty_put_char(tty
, op
^ 0100);
605 !(test_bit(TTY_HW_COOK_OUT
, &tty
->flags
))) {
606 int retval
= do_output_char(c
, tty
, space
);
613 tty_put_char(tty
, c
);
620 /* When end of circular buffer reached, wrap around */
622 cp
-= N_TTY_BUF_SIZE
;
628 tty
->echo_overrun
= 0;
630 int num_processed
= tty
->echo_cnt
- nr
;
631 tty
->echo_pos
+= num_processed
;
632 tty
->echo_pos
&= N_TTY_BUF_SIZE
- 1;
634 if (num_processed
> 0)
635 tty
->echo_overrun
= 0;
638 mutex_unlock(&tty
->echo_lock
);
639 mutex_unlock(&tty
->output_lock
);
641 if (tty
->ops
->flush_chars
)
642 tty
->ops
->flush_chars(tty
);
646 * add_echo_byte - add a byte to the echo buffer
647 * @c: unicode byte to echo
648 * @tty: terminal device
650 * Add a character or operation byte to the echo buffer.
652 * Should be called under the echo lock to protect the echo buffer.
655 static void add_echo_byte(unsigned char c
, struct tty_struct
*tty
)
659 if (tty
->echo_cnt
== N_TTY_BUF_SIZE
) {
660 /* Circular buffer is already at capacity */
661 new_byte_pos
= tty
->echo_pos
;
664 * Since the buffer start position needs to be advanced,
665 * be sure to step by a whole operation byte group.
667 if (tty
->echo_buf
[tty
->echo_pos
] == ECHO_OP_START
) {
668 if (tty
->echo_buf
[(tty
->echo_pos
+ 1) &
669 (N_TTY_BUF_SIZE
- 1)] ==
680 tty
->echo_pos
&= N_TTY_BUF_SIZE
- 1;
682 tty
->echo_overrun
= 1;
684 new_byte_pos
= tty
->echo_pos
+ tty
->echo_cnt
;
685 new_byte_pos
&= N_TTY_BUF_SIZE
- 1;
689 tty
->echo_buf
[new_byte_pos
] = c
;
693 * echo_move_back_col - add operation to move back a column
694 * @tty: terminal device
696 * Add an operation to the echo buffer to move back one column.
698 * Locking: echo_lock to protect the echo buffer
701 static void echo_move_back_col(struct tty_struct
*tty
)
703 mutex_lock(&tty
->echo_lock
);
705 add_echo_byte(ECHO_OP_START
, tty
);
706 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, tty
);
708 mutex_unlock(&tty
->echo_lock
);
712 * echo_set_canon_col - add operation to set the canon column
713 * @tty: terminal device
715 * Add an operation to the echo buffer to set the canon column
716 * to the current column.
718 * Locking: echo_lock to protect the echo buffer
721 static void echo_set_canon_col(struct tty_struct
*tty
)
723 mutex_lock(&tty
->echo_lock
);
725 add_echo_byte(ECHO_OP_START
, tty
);
726 add_echo_byte(ECHO_OP_SET_CANON_COL
, tty
);
728 mutex_unlock(&tty
->echo_lock
);
732 * echo_erase_tab - add operation to erase a tab
733 * @num_chars: number of character columns already used
734 * @after_tab: true if num_chars starts after a previous tab
735 * @tty: terminal device
737 * Add an operation to the echo buffer to erase a tab.
739 * Called by the eraser function, which knows how many character
740 * columns have been used since either a previous tab or the start
741 * of input. This information will be used later, along with
742 * canon column (if applicable), to go back the correct number
745 * Locking: echo_lock to protect the echo buffer
748 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
749 struct tty_struct
*tty
)
751 mutex_lock(&tty
->echo_lock
);
753 add_echo_byte(ECHO_OP_START
, tty
);
754 add_echo_byte(ECHO_OP_ERASE_TAB
, tty
);
756 /* We only need to know this modulo 8 (tab spacing) */
759 /* Set the high bit as a flag if num_chars is after a previous tab */
763 add_echo_byte(num_chars
, tty
);
765 mutex_unlock(&tty
->echo_lock
);
769 * echo_char_raw - echo a character raw
770 * @c: unicode byte to echo
771 * @tty: terminal device
773 * Echo user input back onto the screen. This must be called only when
774 * L_ECHO(tty) is true. Called from the driver receive_buf path.
776 * This variant does not treat control characters specially.
778 * Locking: echo_lock to protect the echo buffer
781 static void echo_char_raw(unsigned char c
, struct tty_struct
*tty
)
783 mutex_lock(&tty
->echo_lock
);
785 if (c
== ECHO_OP_START
) {
786 add_echo_byte(ECHO_OP_START
, tty
);
787 add_echo_byte(ECHO_OP_START
, tty
);
789 add_echo_byte(c
, tty
);
792 mutex_unlock(&tty
->echo_lock
);
796 * echo_char - echo a character
797 * @c: unicode byte to echo
798 * @tty: terminal device
800 * Echo user input back onto the screen. This must be called only when
801 * L_ECHO(tty) is true. Called from the driver receive_buf path.
803 * This variant tags control characters to be echoed as "^X"
804 * (where X is the letter representing the control char).
806 * Locking: echo_lock to protect the echo buffer
809 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
811 mutex_lock(&tty
->echo_lock
);
813 if (c
== ECHO_OP_START
) {
814 add_echo_byte(ECHO_OP_START
, tty
);
815 add_echo_byte(ECHO_OP_START
, tty
);
817 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t')
818 add_echo_byte(ECHO_OP_START
, tty
);
819 add_echo_byte(c
, tty
);
822 mutex_unlock(&tty
->echo_lock
);
826 * finish_erasing - complete erase
827 * @tty: tty doing the erase
830 static inline void finish_erasing(struct tty_struct
*tty
)
833 echo_char_raw('/', tty
);
839 * eraser - handle erase function
840 * @c: character input
841 * @tty: terminal device
843 * Perform erase and necessary output when an erase character is
844 * present in the stream from the driver layer. Handles the complexities
845 * of UTF-8 multibyte symbols.
847 * Locking: read_lock for tty buffers
850 static void eraser(unsigned char c
, struct tty_struct
*tty
)
852 enum { ERASE
, WERASE
, KILL
} kill_type
;
853 int head
, seen_alnums
, cnt
;
856 if (tty
->read_head
== tty
->canon_head
) {
857 /* process_output('\a', tty); */ /* what do you think? */
860 if (c
== ERASE_CHAR(tty
))
862 else if (c
== WERASE_CHAR(tty
))
866 spin_lock_irqsave(&tty
->read_lock
, flags
);
867 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
868 (N_TTY_BUF_SIZE
- 1));
869 tty
->read_head
= tty
->canon_head
;
870 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
873 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
874 spin_lock_irqsave(&tty
->read_lock
, flags
);
875 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
876 (N_TTY_BUF_SIZE
- 1));
877 tty
->read_head
= tty
->canon_head
;
878 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
880 echo_char(KILL_CHAR(tty
), tty
);
881 /* Add a newline if ECHOK is on and ECHOKE is off. */
883 echo_char_raw('\n', tty
);
890 while (tty
->read_head
!= tty
->canon_head
) {
891 head
= tty
->read_head
;
893 /* erase a single possibly multibyte character */
895 head
= (head
- 1) & (N_TTY_BUF_SIZE
-1);
896 c
= tty
->read_buf
[head
];
897 } while (is_continuation(c
, tty
) && head
!= tty
->canon_head
);
899 /* do not partially erase */
900 if (is_continuation(c
, tty
))
903 if (kill_type
== WERASE
) {
904 /* Equivalent to BSD's ALTWERASE. */
905 if (isalnum(c
) || c
== '_')
907 else if (seen_alnums
)
910 cnt
= (tty
->read_head
- head
) & (N_TTY_BUF_SIZE
-1);
911 spin_lock_irqsave(&tty
->read_lock
, flags
);
912 tty
->read_head
= head
;
913 tty
->read_cnt
-= cnt
;
914 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
916 if (L_ECHOPRT(tty
)) {
918 echo_char_raw('\\', tty
);
921 /* if cnt > 1, output a multi-byte character */
924 head
= (head
+1) & (N_TTY_BUF_SIZE
-1);
925 echo_char_raw(tty
->read_buf
[head
], tty
);
926 echo_move_back_col(tty
);
928 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
929 echo_char(ERASE_CHAR(tty
), tty
);
930 } else if (c
== '\t') {
931 unsigned int num_chars
= 0;
933 unsigned long tail
= tty
->read_head
;
936 * Count the columns used for characters
937 * since the start of input or after a
939 * This info is used to go back the correct
942 while (tail
!= tty
->canon_head
) {
943 tail
= (tail
-1) & (N_TTY_BUF_SIZE
-1);
944 c
= tty
->read_buf
[tail
];
948 } else if (iscntrl(c
)) {
951 } else if (!is_continuation(c
, tty
)) {
955 echo_erase_tab(num_chars
, after_tab
, tty
);
957 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
958 echo_char_raw('\b', tty
);
959 echo_char_raw(' ', tty
);
960 echo_char_raw('\b', tty
);
962 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
963 echo_char_raw('\b', tty
);
964 echo_char_raw(' ', tty
);
965 echo_char_raw('\b', tty
);
969 if (kill_type
== ERASE
)
972 if (tty
->read_head
== tty
->canon_head
&& L_ECHO(tty
))
977 * isig - handle the ISIG optio
980 * @flush: force flush
982 * Called when a signal is being sent due to terminal input. This
983 * may caus terminal flushing to take place according to the termios
984 * settings and character used. Called from the driver receive_buf
985 * path so serialized.
987 * Locking: ctrl_lock, read_lock (both via flush buffer)
990 static inline void isig(int sig
, struct tty_struct
*tty
, int flush
)
993 kill_pgrp(tty
->pgrp
, sig
, 1);
994 if (flush
|| !L_NOFLSH(tty
)) {
995 n_tty_flush_buffer(tty
);
996 tty_driver_flush_buffer(tty
);
1001 * n_tty_receive_break - handle break
1004 * An RS232 break event has been hit in the incoming bitstream. This
1005 * can cause a variety of events depending upon the termios settings.
1007 * Called from the receive_buf path so single threaded.
1010 static inline void n_tty_receive_break(struct tty_struct
*tty
)
1014 if (I_BRKINT(tty
)) {
1015 isig(SIGINT
, tty
, 1);
1018 if (I_PARMRK(tty
)) {
1019 put_tty_queue('\377', tty
);
1020 put_tty_queue('\0', tty
);
1022 put_tty_queue('\0', tty
);
1023 wake_up_interruptible(&tty
->read_wait
);
1027 * n_tty_receive_overrun - handle overrun reporting
1030 * Data arrived faster than we could process it. While the tty
1031 * driver has flagged this the bits that were missed are gone
1034 * Called from the receive_buf path so single threaded. Does not
1035 * need locking as num_overrun and overrun_time are function
1039 static inline void n_tty_receive_overrun(struct tty_struct
*tty
)
1044 if (time_before(tty
->overrun_time
, jiffies
- HZ
) ||
1045 time_after(tty
->overrun_time
, jiffies
)) {
1046 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1049 tty
->overrun_time
= jiffies
;
1050 tty
->num_overrun
= 0;
1055 * n_tty_receive_parity_error - error notifier
1056 * @tty: terminal device
1059 * Process a parity error and queue the right data to indicate
1060 * the error case if necessary. Locking as per n_tty_receive_buf.
1062 static inline void n_tty_receive_parity_error(struct tty_struct
*tty
,
1067 if (I_PARMRK(tty
)) {
1068 put_tty_queue('\377', tty
);
1069 put_tty_queue('\0', tty
);
1070 put_tty_queue(c
, tty
);
1071 } else if (I_INPCK(tty
))
1072 put_tty_queue('\0', tty
);
1074 put_tty_queue(c
, tty
);
1075 wake_up_interruptible(&tty
->read_wait
);
1079 * n_tty_receive_char - perform processing
1080 * @tty: terminal device
1083 * Process an individual character of input received from the driver.
1084 * This is serialized with respect to itself by the rules for the
1088 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1090 unsigned long flags
;
1094 put_tty_queue(c
, tty
);
1100 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1103 if (L_EXTPROC(tty
)) {
1104 put_tty_queue(c
, tty
);
1108 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) &&
1109 I_IXANY(tty
) && c
!= START_CHAR(tty
) && c
!= STOP_CHAR(tty
) &&
1110 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) && c
!= SUSP_CHAR(tty
)) {
1112 process_echoes(tty
);
1117 if (c
== START_CHAR(tty
)) {
1119 process_echoes(tty
);
1120 } else if (c
== STOP_CHAR(tty
))
1127 * If the previous character was LNEXT, or we know that this
1128 * character is not one of the characters that we'll have to
1129 * handle specially, do shortcut processing to speed things
1132 if (!test_bit(c
, tty
->process_char_map
) || tty
->lnext
) {
1134 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1135 if (tty
->read_cnt
>= (N_TTY_BUF_SIZE
- parmrk
- 1)) {
1136 /* beep if no space */
1138 process_output('\a', tty
);
1142 finish_erasing(tty
);
1143 /* Record the column of first canon char. */
1144 if (tty
->canon_head
== tty
->read_head
)
1145 echo_set_canon_col(tty
);
1147 process_echoes(tty
);
1150 put_tty_queue(c
, tty
);
1151 put_tty_queue(c
, tty
);
1156 if (c
== START_CHAR(tty
)) {
1158 process_echoes(tty
);
1161 if (c
== STOP_CHAR(tty
)) {
1170 if (c
== INTR_CHAR(tty
))
1173 if (c
== QUIT_CHAR(tty
))
1176 if (c
== SUSP_CHAR(tty
)) {
1179 * Note that we do not use isig() here because we want
1181 * 1) flush, 2) echo, 3) signal
1183 if (!L_NOFLSH(tty
)) {
1184 n_tty_flush_buffer(tty
);
1185 tty_driver_flush_buffer(tty
);
1191 process_echoes(tty
);
1194 kill_pgrp(tty
->pgrp
, signal
, 1);
1204 } else if (c
== '\n' && I_INLCR(tty
))
1208 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1209 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1211 process_echoes(tty
);
1214 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1217 finish_erasing(tty
);
1218 if (L_ECHOCTL(tty
)) {
1219 echo_char_raw('^', tty
);
1220 echo_char_raw('\b', tty
);
1221 process_echoes(tty
);
1226 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
1228 unsigned long tail
= tty
->canon_head
;
1230 finish_erasing(tty
);
1232 echo_char_raw('\n', tty
);
1233 while (tail
!= tty
->read_head
) {
1234 echo_char(tty
->read_buf
[tail
], tty
);
1235 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
1237 process_echoes(tty
);
1241 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
) {
1243 process_output('\a', tty
);
1246 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1247 echo_char_raw('\n', tty
);
1248 process_echoes(tty
);
1250 goto handle_newline
;
1252 if (c
== EOF_CHAR(tty
)) {
1253 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
)
1255 if (tty
->canon_head
!= tty
->read_head
)
1256 set_bit(TTY_PUSH
, &tty
->flags
);
1257 c
= __DISABLED_CHAR
;
1258 goto handle_newline
;
1260 if ((c
== EOL_CHAR(tty
)) ||
1261 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1262 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1264 if (tty
->read_cnt
>= (N_TTY_BUF_SIZE
- parmrk
)) {
1266 process_output('\a', tty
);
1270 /* Record the column of first canon char. */
1271 if (tty
->canon_head
== tty
->read_head
)
1272 echo_set_canon_col(tty
);
1274 process_echoes(tty
);
1277 put_tty_queue(c
, tty
);
1280 spin_lock_irqsave(&tty
->read_lock
, flags
);
1281 set_bit(tty
->read_head
, tty
->read_flags
);
1282 put_tty_queue_nolock(c
, tty
);
1283 tty
->canon_head
= tty
->read_head
;
1285 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1286 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1287 if (waitqueue_active(&tty
->read_wait
))
1288 wake_up_interruptible(&tty
->read_wait
);
1293 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1294 if (tty
->read_cnt
>= (N_TTY_BUF_SIZE
- parmrk
- 1)) {
1295 /* beep if no space */
1297 process_output('\a', tty
);
1301 finish_erasing(tty
);
1303 echo_char_raw('\n', tty
);
1305 /* Record the column of first canon char. */
1306 if (tty
->canon_head
== tty
->read_head
)
1307 echo_set_canon_col(tty
);
1310 process_echoes(tty
);
1314 put_tty_queue(c
, tty
);
1316 put_tty_queue(c
, tty
);
1321 * n_tty_write_wakeup - asynchronous I/O notifier
1324 * Required for the ptys, serial driver etc. since processes
1325 * that attach themselves to the master and rely on ASYNC
1326 * IO must be woken up
1329 static void n_tty_write_wakeup(struct tty_struct
*tty
)
1331 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
1332 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
1336 * n_tty_receive_buf - data receive
1337 * @tty: terminal device
1340 * @count: characters
1342 * Called by the terminal driver when a block of characters has
1343 * been received. This function must be called from soft contexts
1344 * not from interrupt context. The driver is responsible for making
1345 * calls one at a time and in order (or using flush_to_ldisc)
1348 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1349 char *fp
, int count
)
1351 const unsigned char *p
;
1352 char *f
, flags
= TTY_NORMAL
;
1355 unsigned long cpuflags
;
1360 if (tty
->real_raw
) {
1361 spin_lock_irqsave(&tty
->read_lock
, cpuflags
);
1362 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
1363 N_TTY_BUF_SIZE
- tty
->read_head
);
1365 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
1366 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
1371 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
1372 N_TTY_BUF_SIZE
- tty
->read_head
);
1374 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
1375 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
1377 spin_unlock_irqrestore(&tty
->read_lock
, cpuflags
);
1379 for (i
= count
, p
= cp
, f
= fp
; i
; i
--, p
++) {
1384 n_tty_receive_char(tty
, *p
);
1387 n_tty_receive_break(tty
);
1391 n_tty_receive_parity_error(tty
, *p
);
1394 n_tty_receive_overrun(tty
);
1397 printk(KERN_ERR
"%s: unknown flag %d\n",
1398 tty_name(tty
, buf
), flags
);
1402 if (tty
->ops
->flush_chars
)
1403 tty
->ops
->flush_chars(tty
);
1406 n_tty_set_room(tty
);
1408 if ((!tty
->icanon
&& (tty
->read_cnt
>= tty
->minimum_to_wake
)) ||
1410 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1411 if (waitqueue_active(&tty
->read_wait
))
1412 wake_up_interruptible(&tty
->read_wait
);
1416 * Check the remaining room for the input canonicalization
1417 * mode. We don't want to throttle the driver if we're in
1418 * canonical mode and don't have a newline yet!
1420 if (tty
->receive_room
< TTY_THRESHOLD_THROTTLE
)
1424 int is_ignored(int sig
)
1426 return (sigismember(¤t
->blocked
, sig
) ||
1427 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1431 * n_tty_set_termios - termios data changed
1433 * @old: previous data
1435 * Called by the tty layer when the user changes termios flags so
1436 * that the line discipline can plan ahead. This function cannot sleep
1437 * and is protected from re-entry by the tty layer. The user is
1438 * guaranteed that this function will not be re-entered or in progress
1439 * when the ldisc is closed.
1441 * Locking: Caller holds tty->termios_mutex
1444 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1446 int canon_change
= 1;
1450 canon_change
= (old
->c_lflag
^ tty
->termios
->c_lflag
) & ICANON
;
1452 memset(&tty
->read_flags
, 0, sizeof tty
->read_flags
);
1453 tty
->canon_head
= tty
->read_tail
;
1454 tty
->canon_data
= 0;
1458 if (canon_change
&& !L_ICANON(tty
) && tty
->read_cnt
)
1459 wake_up_interruptible(&tty
->read_wait
);
1461 tty
->icanon
= (L_ICANON(tty
) != 0);
1462 if (test_bit(TTY_HW_COOK_IN
, &tty
->flags
)) {
1465 n_tty_set_room(tty
);
1468 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1469 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1470 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1472 memset(tty
->process_char_map
, 0, 256/8);
1474 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1475 set_bit('\r', tty
->process_char_map
);
1477 set_bit('\n', tty
->process_char_map
);
1479 if (L_ICANON(tty
)) {
1480 set_bit(ERASE_CHAR(tty
), tty
->process_char_map
);
1481 set_bit(KILL_CHAR(tty
), tty
->process_char_map
);
1482 set_bit(EOF_CHAR(tty
), tty
->process_char_map
);
1483 set_bit('\n', tty
->process_char_map
);
1484 set_bit(EOL_CHAR(tty
), tty
->process_char_map
);
1485 if (L_IEXTEN(tty
)) {
1486 set_bit(WERASE_CHAR(tty
),
1487 tty
->process_char_map
);
1488 set_bit(LNEXT_CHAR(tty
),
1489 tty
->process_char_map
);
1490 set_bit(EOL2_CHAR(tty
),
1491 tty
->process_char_map
);
1493 set_bit(REPRINT_CHAR(tty
),
1494 tty
->process_char_map
);
1498 set_bit(START_CHAR(tty
), tty
->process_char_map
);
1499 set_bit(STOP_CHAR(tty
), tty
->process_char_map
);
1502 set_bit(INTR_CHAR(tty
), tty
->process_char_map
);
1503 set_bit(QUIT_CHAR(tty
), tty
->process_char_map
);
1504 set_bit(SUSP_CHAR(tty
), tty
->process_char_map
);
1506 clear_bit(__DISABLED_CHAR
, tty
->process_char_map
);
1511 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1512 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1513 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1518 n_tty_set_room(tty
);
1519 /* The termios change make the tty ready for I/O */
1520 wake_up_interruptible(&tty
->write_wait
);
1521 wake_up_interruptible(&tty
->read_wait
);
1525 * n_tty_close - close the ldisc for this tty
1528 * Called from the terminal layer when this line discipline is
1529 * being shut down, either because of a close or becsuse of a
1530 * discipline change. The function will not be called while other
1531 * ldisc methods are in progress.
1534 static void n_tty_close(struct tty_struct
*tty
)
1536 n_tty_flush_buffer(tty
);
1537 if (tty
->read_buf
) {
1538 kfree(tty
->read_buf
);
1539 tty
->read_buf
= NULL
;
1541 if (tty
->echo_buf
) {
1542 kfree(tty
->echo_buf
);
1543 tty
->echo_buf
= NULL
;
1548 * n_tty_open - open an ldisc
1549 * @tty: terminal to open
1551 * Called when this line discipline is being attached to the
1552 * terminal device. Can sleep. Called serialized so that no
1553 * other events will occur in parallel. No further open will occur
1557 static int n_tty_open(struct tty_struct
*tty
)
1562 /* These are ugly. Currently a malloc failure here can panic */
1563 if (!tty
->read_buf
) {
1564 tty
->read_buf
= kzalloc(N_TTY_BUF_SIZE
, GFP_KERNEL
);
1568 if (!tty
->echo_buf
) {
1569 tty
->echo_buf
= kzalloc(N_TTY_BUF_SIZE
, GFP_KERNEL
);
1574 reset_buffer_flags(tty
);
1576 n_tty_set_termios(tty
, NULL
);
1577 tty
->minimum_to_wake
= 1;
1582 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1584 tty_flush_to_ldisc(tty
);
1585 if (tty
->icanon
&& !L_EXTPROC(tty
)) {
1586 if (tty
->canon_data
)
1588 } else if (tty
->read_cnt
>= (amt
? amt
: 1))
1595 * copy_from_read_buf - copy read data directly
1596 * @tty: terminal device
1600 * Helper function to speed up n_tty_read. It is only called when
1601 * ICANON is off; it copies characters straight from the tty queue to
1602 * user space directly. It can be profitably called twice; once to
1603 * drain the space from the tail pointer to the (physical) end of the
1604 * buffer, and once to drain the space from the (physical) beginning of
1605 * the buffer to head pointer.
1607 * Called under the tty->atomic_read_lock sem
1611 static int copy_from_read_buf(struct tty_struct
*tty
,
1612 unsigned char __user
**b
,
1618 unsigned long flags
;
1621 spin_lock_irqsave(&tty
->read_lock
, flags
);
1622 n
= min(tty
->read_cnt
, N_TTY_BUF_SIZE
- tty
->read_tail
);
1624 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1626 retval
= copy_to_user(*b
, &tty
->read_buf
[tty
->read_tail
], n
);
1628 tty_audit_add_data(tty
, &tty
->read_buf
[tty
->read_tail
], n
);
1629 spin_lock_irqsave(&tty
->read_lock
, flags
);
1630 tty
->read_tail
= (tty
->read_tail
+ n
) & (N_TTY_BUF_SIZE
-1);
1632 /* Turn single EOF into zero-length read */
1633 if (L_EXTPROC(tty
) && tty
->icanon
&& n
== 1) {
1634 if (!tty
->read_cnt
&& (*b
)[n
-1] == EOF_CHAR(tty
))
1637 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1644 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
1648 static int job_control(struct tty_struct
*tty
, struct file
*file
)
1650 /* Job control check -- must be done at start and after
1651 every sleep (POSIX.1 7.1.1.4). */
1652 /* NOTE: not yet done after every sleep pending a thorough
1653 check of the logic of this change. -- jlc */
1654 /* don't stop on /dev/console */
1655 if (file
->f_op
->write
!= redirected_tty_write
&&
1656 current
->signal
->tty
== tty
) {
1658 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
1659 else if (task_pgrp(current
) != tty
->pgrp
) {
1660 if (is_ignored(SIGTTIN
) ||
1661 is_current_pgrp_orphaned())
1663 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
1664 set_thread_flag(TIF_SIGPENDING
);
1665 return -ERESTARTSYS
;
1673 * n_tty_read - read function for tty
1675 * @file: file object
1676 * @buf: userspace buffer pointer
1679 * Perform reads for the line discipline. We are guaranteed that the
1680 * line discipline will not be closed under us but we may get multiple
1681 * parallel readers and must handle this ourselves. We may also get
1682 * a hangup. Always called in user context, may sleep.
1684 * This code must be sure never to sleep through a hangup.
1687 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
1688 unsigned char __user
*buf
, size_t nr
)
1690 unsigned char __user
*b
= buf
;
1691 DECLARE_WAITQUEUE(wait
, current
);
1697 unsigned long flags
;
1702 BUG_ON(!tty
->read_buf
);
1704 c
= job_control(tty
, file
);
1709 timeout
= MAX_SCHEDULE_TIMEOUT
;
1711 time
= (HZ
/ 10) * TIME_CHAR(tty
);
1712 minimum
= MIN_CHAR(tty
);
1715 tty
->minimum_to_wake
= 1;
1716 else if (!waitqueue_active(&tty
->read_wait
) ||
1717 (tty
->minimum_to_wake
> minimum
))
1718 tty
->minimum_to_wake
= minimum
;
1725 tty
->minimum_to_wake
= minimum
= 1;
1730 * Internal serialization of reads.
1732 if (file
->f_flags
& O_NONBLOCK
) {
1733 if (!mutex_trylock(&tty
->atomic_read_lock
))
1736 if (mutex_lock_interruptible(&tty
->atomic_read_lock
))
1737 return -ERESTARTSYS
;
1739 packet
= tty
->packet
;
1741 add_wait_queue(&tty
->read_wait
, &wait
);
1743 /* First test for status change. */
1744 if (packet
&& tty
->link
->ctrl_status
) {
1748 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
1749 cs
= tty
->link
->ctrl_status
;
1750 tty
->link
->ctrl_status
= 0;
1751 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
1752 if (tty_put_user(tty
, cs
, b
++)) {
1760 /* This statement must be first before checking for input
1761 so that any interrupt will set the state back to
1763 set_current_state(TASK_INTERRUPTIBLE
);
1765 if (((minimum
- (b
- buf
)) < tty
->minimum_to_wake
) &&
1766 ((minimum
- (b
- buf
)) >= 1))
1767 tty
->minimum_to_wake
= (minimum
- (b
- buf
));
1769 if (!input_available_p(tty
, 0)) {
1770 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
1774 if (tty_hung_up_p(file
))
1778 if (file
->f_flags
& O_NONBLOCK
) {
1782 if (signal_pending(current
)) {
1783 retval
= -ERESTARTSYS
;
1786 n_tty_set_room(tty
);
1787 timeout
= schedule_timeout(timeout
);
1790 __set_current_state(TASK_RUNNING
);
1792 /* Deal with packet mode. */
1793 if (packet
&& b
== buf
) {
1794 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
1802 if (tty
->icanon
&& !L_EXTPROC(tty
)) {
1803 /* N.B. avoid overrun if nr == 0 */
1804 while (nr
&& tty
->read_cnt
) {
1807 eol
= test_and_clear_bit(tty
->read_tail
,
1809 c
= tty
->read_buf
[tty
->read_tail
];
1810 spin_lock_irqsave(&tty
->read_lock
, flags
);
1811 tty
->read_tail
= ((tty
->read_tail
+1) &
1812 (N_TTY_BUF_SIZE
-1));
1815 /* this test should be redundant:
1816 * we shouldn't be reading data if
1819 if (--tty
->canon_data
< 0)
1820 tty
->canon_data
= 0;
1822 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1824 if (!eol
|| (c
!= __DISABLED_CHAR
)) {
1825 if (tty_put_user(tty
, c
, b
++)) {
1833 tty_audit_push(tty
);
1841 /* The copy function takes the read lock and handles
1842 locking internally for this case */
1843 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
1844 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
1851 /* If there is enough space in the read buffer now, let the
1852 * low-level driver know. We use n_tty_chars_in_buffer() to
1853 * check the buffer, as it now knows about canonical mode.
1854 * Otherwise, if the driver is throttled and the line is
1855 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1856 * we won't get any more characters.
1858 if (n_tty_chars_in_buffer(tty
) <= TTY_THRESHOLD_UNTHROTTLE
) {
1859 n_tty_set_room(tty
);
1860 check_unthrottle(tty
);
1863 if (b
- buf
>= minimum
)
1868 mutex_unlock(&tty
->atomic_read_lock
);
1869 remove_wait_queue(&tty
->read_wait
, &wait
);
1871 if (!waitqueue_active(&tty
->read_wait
))
1872 tty
->minimum_to_wake
= minimum
;
1874 __set_current_state(TASK_RUNNING
);
1879 clear_bit(TTY_PUSH
, &tty
->flags
);
1880 } else if (test_and_clear_bit(TTY_PUSH
, &tty
->flags
))
1883 n_tty_set_room(tty
);
1888 * n_tty_write - write function for tty
1890 * @file: file object
1891 * @buf: userspace buffer pointer
1894 * Write function of the terminal device. This is serialized with
1895 * respect to other write callers but not to termios changes, reads
1896 * and other such events. Since the receive code will echo characters,
1897 * thus calling driver write methods, the output_lock is used in
1898 * the output processing functions called here as well as in the
1899 * echo processing function to protect the column state and space
1900 * left in the buffer.
1902 * This code must be sure never to sleep through a hangup.
1904 * Locking: output_lock to protect column state and space left
1905 * (note that the process_output*() functions take this
1909 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
1910 const unsigned char *buf
, size_t nr
)
1912 const unsigned char *b
= buf
;
1913 DECLARE_WAITQUEUE(wait
, current
);
1917 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1918 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
1919 retval
= tty_check_change(tty
);
1924 /* Write out any echoed characters that are still pending */
1925 process_echoes(tty
);
1927 add_wait_queue(&tty
->write_wait
, &wait
);
1929 set_current_state(TASK_INTERRUPTIBLE
);
1930 if (signal_pending(current
)) {
1931 retval
= -ERESTARTSYS
;
1934 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
1938 if (O_OPOST(tty
) && !(test_bit(TTY_HW_COOK_OUT
, &tty
->flags
))) {
1940 ssize_t num
= process_output_block(tty
, b
, nr
);
1952 if (process_output(c
, tty
) < 0)
1956 if (tty
->ops
->flush_chars
)
1957 tty
->ops
->flush_chars(tty
);
1960 c
= tty
->ops
->write(tty
, b
, nr
);
1973 if (file
->f_flags
& O_NONBLOCK
) {
1980 __set_current_state(TASK_RUNNING
);
1981 remove_wait_queue(&tty
->write_wait
, &wait
);
1982 if (b
- buf
!= nr
&& tty
->fasync
)
1983 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
1984 return (b
- buf
) ? b
- buf
: retval
;
1988 * n_tty_poll - poll method for N_TTY
1989 * @tty: terminal device
1990 * @file: file accessing it
1993 * Called when the line discipline is asked to poll() for data or
1994 * for special events. This code is not serialized with respect to
1995 * other events save open/close.
1997 * This code must be sure never to sleep through a hangup.
1998 * Called without the kernel lock held - fine
2001 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2004 unsigned int mask
= 0;
2006 poll_wait(file
, &tty
->read_wait
, wait
);
2007 poll_wait(file
, &tty
->write_wait
, wait
);
2008 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
2009 mask
|= POLLIN
| POLLRDNORM
;
2010 if (tty
->packet
&& tty
->link
->ctrl_status
)
2011 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2012 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2014 if (tty_hung_up_p(file
))
2016 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2017 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2018 tty
->minimum_to_wake
= MIN_CHAR(tty
);
2020 tty
->minimum_to_wake
= 1;
2022 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2023 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2024 tty_write_room(tty
) > 0)
2025 mask
|= POLLOUT
| POLLWRNORM
;
2029 static unsigned long inq_canon(struct tty_struct
*tty
)
2033 if (!tty
->canon_data
)
2035 head
= tty
->canon_head
;
2036 tail
= tty
->read_tail
;
2037 nr
= (head
- tail
) & (N_TTY_BUF_SIZE
-1);
2038 /* Skip EOF-chars.. */
2039 while (head
!= tail
) {
2040 if (test_bit(tail
, tty
->read_flags
) &&
2041 tty
->read_buf
[tail
] == __DISABLED_CHAR
)
2043 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
2048 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2049 unsigned int cmd
, unsigned long arg
)
2055 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2057 retval
= tty
->read_cnt
;
2059 retval
= inq_canon(tty
);
2060 return put_user(retval
, (unsigned int __user
*) arg
);
2062 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2066 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2067 .magic
= TTY_LDISC_MAGIC
,
2070 .close
= n_tty_close
,
2071 .flush_buffer
= n_tty_flush_buffer
,
2072 .chars_in_buffer
= n_tty_chars_in_buffer
,
2074 .write
= n_tty_write
,
2075 .ioctl
= n_tty_ioctl
,
2076 .set_termios
= n_tty_set_termios
,
2078 .receive_buf
= n_tty_receive_buf
,
2079 .write_wakeup
= n_tty_write_wakeup
2083 * n_tty_inherit_ops - inherit N_TTY methods
2084 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2086 * Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
2090 void n_tty_inherit_ops(struct tty_ldisc_ops
*ops
)
2092 *ops
= tty_ldisc_N_TTY
;
2094 ops
->refcount
= ops
->flags
= 0;
2096 EXPORT_SYMBOL_GPL(n_tty_inherit_ops
);