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>
52 #include <asm/system.h>
54 /* number of characters left in xmit buffer before select has we have room */
55 #define WAKEUP_CHARS 256
58 * This defines the low- and high-watermarks for throttling and
59 * unthrottling the TTY driver. These watermarks are used for
60 * controlling the space in the read buffer.
62 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
63 #define TTY_THRESHOLD_UNTHROTTLE 128
66 * Special byte codes used in the echo buffer to represent operations
67 * or special handling of characters. Bytes in the echo buffer that
68 * are not part of such special blocks are treated as normal character
71 #define ECHO_OP_START 0xff
72 #define ECHO_OP_MOVE_BACK_COL 0x80
73 #define ECHO_OP_SET_CANON_COL 0x81
74 #define ECHO_OP_ERASE_TAB 0x82
76 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
77 unsigned char __user
*ptr
)
79 tty_audit_add_data(tty
, &x
, 1);
80 return put_user(x
, ptr
);
84 * n_tty_set__room - receive space
87 * Called by the driver to find out how much data it is
88 * permitted to feed to the line discipline without any being lost
89 * and thus to manage flow control. Not serialized. Answers for the
93 static void n_tty_set_room(struct tty_struct
*tty
)
95 /* tty->read_cnt is not read locked ? */
96 int left
= N_TTY_BUF_SIZE
- tty
->read_cnt
- 1;
99 * If we are doing input canonicalization, and there are no
100 * pending newlines, let characters through without limit, so
101 * that erase characters will be handled. Other excess
102 * characters will be beeped.
105 left
= tty
->icanon
&& !tty
->canon_data
;
106 tty
->receive_room
= left
;
109 static void put_tty_queue_nolock(unsigned char c
, struct tty_struct
*tty
)
111 if (tty
->read_cnt
< N_TTY_BUF_SIZE
) {
112 tty
->read_buf
[tty
->read_head
] = c
;
113 tty
->read_head
= (tty
->read_head
+ 1) & (N_TTY_BUF_SIZE
-1);
119 * put_tty_queue - add character to tty
123 * Add a character to the tty read_buf queue. This is done under the
124 * read_lock to serialize character addition and also to protect us
125 * against parallel reads or flushes
128 static void put_tty_queue(unsigned char c
, struct tty_struct
*tty
)
132 * The problem of stomping on the buffers ends here.
133 * Why didn't anyone see this one coming? --AJK
135 spin_lock_irqsave(&tty
->read_lock
, flags
);
136 put_tty_queue_nolock(c
, tty
);
137 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
141 * check_unthrottle - allow new receive data
144 * Check whether to call the driver unthrottle functions
146 * Can sleep, may be called under the atomic_read_lock mutex but
147 * this is not guaranteed.
149 static void check_unthrottle(struct tty_struct
*tty
)
156 * reset_buffer_flags - reset buffer state
157 * @tty: terminal to reset
159 * Reset the read buffer counters, clear the flags,
160 * and make sure the driver is unthrottled. Called
161 * from n_tty_open() and n_tty_flush_buffer().
163 * Locking: tty_read_lock for read fields.
166 static void reset_buffer_flags(struct tty_struct
*tty
)
170 spin_lock_irqsave(&tty
->read_lock
, flags
);
171 tty
->read_head
= tty
->read_tail
= tty
->read_cnt
= 0;
172 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
174 mutex_lock(&tty
->echo_lock
);
175 tty
->echo_pos
= tty
->echo_cnt
= tty
->echo_overrun
= 0;
176 mutex_unlock(&tty
->echo_lock
);
178 tty
->canon_head
= tty
->canon_data
= tty
->erasing
= 0;
179 memset(&tty
->read_flags
, 0, sizeof tty
->read_flags
);
181 check_unthrottle(tty
);
185 * n_tty_flush_buffer - clean input queue
186 * @tty: terminal device
188 * Flush the input buffer. Called when the line discipline is
189 * being closed, when the tty layer wants the buffer flushed (eg
190 * at hangup) or when the N_TTY line discipline internally has to
191 * clean the pending queue (for example some signals).
193 * Locking: ctrl_lock, read_lock.
196 static void n_tty_flush_buffer(struct tty_struct
*tty
)
199 /* clear everything and unthrottle the driver */
200 reset_buffer_flags(tty
);
205 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
206 if (tty
->link
->packet
) {
207 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
208 wake_up_interruptible(&tty
->link
->read_wait
);
210 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
214 * n_tty_chars_in_buffer - report available bytes
217 * Report the number of characters buffered to be delivered to user
218 * at this instant in time.
223 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
228 spin_lock_irqsave(&tty
->read_lock
, flags
);
231 } else if (tty
->canon_data
) {
232 n
= (tty
->canon_head
> tty
->read_tail
) ?
233 tty
->canon_head
- tty
->read_tail
:
234 tty
->canon_head
+ (N_TTY_BUF_SIZE
- tty
->read_tail
);
236 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
241 * is_utf8_continuation - utf8 multibyte check
244 * Returns true if the utf8 character 'c' is a multibyte continuation
245 * character. We use this to correctly compute the on screen size
246 * of the character when printing
249 static inline int is_utf8_continuation(unsigned char c
)
251 return (c
& 0xc0) == 0x80;
255 * is_continuation - multibyte check
258 * Returns true if the utf8 character 'c' is a multibyte continuation
259 * character and the terminal is in unicode mode.
262 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
264 return I_IUTF8(tty
) && is_utf8_continuation(c
);
268 * do_output_char - output one character
269 * @c: character (or partial unicode symbol)
270 * @tty: terminal device
271 * @space: space available in tty driver write buffer
273 * This is a helper function that handles one output character
274 * (including special characters like TAB, CR, LF, etc.),
275 * putting the results in the tty driver's write buffer.
277 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
278 * and NLDLY. They simply aren't relevant in the world today.
279 * If you ever need them, add them here.
281 * Returns the number of bytes of buffer space used or -1 if
284 * Locking: should be called under the output_lock to protect
285 * the column state and space left in the buffer
288 static int do_output_char(unsigned char c
, struct tty_struct
*tty
, int space
)
302 tty
->canon_column
= tty
->column
= 0;
303 tty_put_char(tty
, '\r');
304 tty_put_char(tty
, c
);
307 tty
->canon_column
= tty
->column
;
310 if (O_ONOCR(tty
) && tty
->column
== 0)
315 tty
->canon_column
= tty
->column
= 0;
318 tty
->canon_column
= tty
->column
= 0;
321 spaces
= 8 - (tty
->column
& 7);
322 if (O_TABDLY(tty
) == XTABS
) {
325 tty
->column
+= spaces
;
326 tty
->ops
->write(tty
, " ", spaces
);
329 tty
->column
+= spaces
;
339 if (!is_continuation(c
, tty
))
345 tty_put_char(tty
, c
);
350 * process_output - output post processor
351 * @c: character (or partial unicode symbol)
352 * @tty: terminal device
354 * Perform OPOST processing. Returns -1 when the output device is
355 * full and the character must be retried.
357 * Locking: output_lock to protect column state and space left
358 * (also, this is called from n_tty_write under the
359 * tty layer write lock)
362 static int process_output(unsigned char c
, struct tty_struct
*tty
)
366 mutex_lock(&tty
->output_lock
);
368 space
= tty_write_room(tty
);
369 retval
= do_output_char(c
, tty
, space
);
371 mutex_unlock(&tty
->output_lock
);
379 * process_output_block - block post processor
380 * @tty: terminal device
381 * @inbuf: user buffer
382 * @nr: number of bytes
384 * This path is used to speed up block console writes, among other
385 * things when processing blocks of output data. It handles only
386 * the simple cases normally found and helps to generate blocks of
387 * symbols for the console driver and thus improve performance.
389 * Locking: output_lock to protect column state and space left
390 * (also, this is called from n_tty_write under the
391 * tty layer write lock)
394 static ssize_t
process_output_block(struct tty_struct
*tty
,
395 const unsigned char *buf
, unsigned int nr
)
399 const unsigned char *cp
;
401 mutex_lock(&tty
->output_lock
);
403 space
= tty_write_room(tty
);
405 mutex_unlock(&tty
->output_lock
);
411 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
412 unsigned char c
= *cp
;
420 tty
->canon_column
= tty
->column
;
423 if (O_ONOCR(tty
) && tty
->column
== 0)
427 tty
->canon_column
= tty
->column
= 0;
439 if (!is_continuation(c
, tty
))
446 i
= tty
->ops
->write(tty
, buf
, i
);
448 mutex_unlock(&tty
->output_lock
);
453 * process_echoes - write pending echo characters
454 * @tty: terminal device
456 * Write previously buffered echo (and other ldisc-generated)
457 * characters to the tty.
459 * Characters generated by the ldisc (including echoes) need to
460 * be buffered because the driver's write buffer can fill during
461 * heavy program output. Echoing straight to the driver will
462 * often fail under these conditions, causing lost characters and
463 * resulting mismatches of ldisc state information.
465 * Since the ldisc state must represent the characters actually sent
466 * to the driver at the time of the write, operations like certain
467 * changes in column state are also saved in the buffer and executed
470 * A circular fifo buffer is used so that the most recent characters
471 * are prioritized. Also, when control characters are echoed with a
472 * prefixed "^", the pair is treated atomically and thus not separated.
474 * Locking: output_lock to protect column state and space left,
475 * echo_lock to protect the echo buffer
478 static void process_echoes(struct tty_struct
*tty
)
482 unsigned char *cp
, *buf_end
;
487 mutex_lock(&tty
->output_lock
);
488 mutex_lock(&tty
->echo_lock
);
490 space
= tty_write_room(tty
);
492 buf_end
= tty
->echo_buf
+ N_TTY_BUF_SIZE
;
493 cp
= tty
->echo_buf
+ tty
->echo_pos
;
497 if (c
== ECHO_OP_START
) {
500 int no_space_left
= 0;
503 * If the buffer byte is the start of a multi-byte
504 * operation, get the next byte, which is either the
505 * op code or a control character value.
509 opp
-= N_TTY_BUF_SIZE
;
513 unsigned int num_chars
, num_bs
;
515 case ECHO_OP_ERASE_TAB
:
516 if (++opp
== buf_end
)
517 opp
-= N_TTY_BUF_SIZE
;
521 * Determine how many columns to go back
522 * in order to erase the tab.
523 * This depends on the number of columns
524 * used by other characters within the tab
525 * area. If this (modulo 8) count is from
526 * the start of input rather than from a
527 * previous tab, we offset by canon column.
528 * Otherwise, tab spacing is normal.
530 if (!(num_chars
& 0x80))
531 num_chars
+= tty
->canon_column
;
532 num_bs
= 8 - (num_chars
& 7);
534 if (num_bs
> space
) {
540 tty_put_char(tty
, '\b');
548 case ECHO_OP_SET_CANON_COL
:
549 tty
->canon_column
= tty
->column
;
554 case ECHO_OP_MOVE_BACK_COL
:
562 /* This is an escaped echo op start code */
567 tty_put_char(tty
, ECHO_OP_START
);
576 if (L_ECHOCTL(tty
)) {
578 * Ensure there is enough space
579 * for the whole ctrl pair.
585 tty_put_char(tty
, '^');
586 tty_put_char(tty
, op
^ 0100);
594 tty_put_char(tty
, op
);
599 * If above falls through, this was an
611 retval
= do_output_char(c
, tty
, space
);
619 /* When end of circular buffer reached, wrap around */
621 cp
-= N_TTY_BUF_SIZE
;
627 tty
->echo_overrun
= 0;
629 int num_processed
= tty
->echo_cnt
- nr
;
630 tty
->echo_pos
+= num_processed
;
631 tty
->echo_pos
&= N_TTY_BUF_SIZE
- 1;
633 if (num_processed
> 0)
634 tty
->echo_overrun
= 0;
637 mutex_unlock(&tty
->echo_lock
);
638 mutex_unlock(&tty
->output_lock
);
640 if (tty
->ops
->flush_chars
)
641 tty
->ops
->flush_chars(tty
);
645 * add_echo_byte - add a byte to the echo buffer
646 * @c: unicode byte to echo
647 * @tty: terminal device
649 * Add a character or operation byte to the echo buffer.
651 * Should be called under the echo lock to protect the echo buffer.
654 static void add_echo_byte(unsigned char c
, struct tty_struct
*tty
)
658 if (tty
->echo_cnt
== N_TTY_BUF_SIZE
) {
659 /* Circular buffer is already at capacity */
660 new_byte_pos
= tty
->echo_pos
;
663 * Since the buffer start position needs to be advanced,
664 * be sure to step by a whole operation byte group.
666 if (tty
->echo_buf
[tty
->echo_pos
] == ECHO_OP_START
) {
667 if (tty
->echo_buf
[(tty
->echo_pos
+ 1) &
668 (N_TTY_BUF_SIZE
- 1)] ==
679 tty
->echo_pos
&= N_TTY_BUF_SIZE
- 1;
681 tty
->echo_overrun
= 1;
683 new_byte_pos
= tty
->echo_pos
+ tty
->echo_cnt
;
684 new_byte_pos
&= N_TTY_BUF_SIZE
- 1;
688 tty
->echo_buf
[new_byte_pos
] = c
;
692 * echo_move_back_col - add operation to move back a column
693 * @tty: terminal device
695 * Add an operation to the echo buffer to move back one column.
697 * Locking: echo_lock to protect the echo buffer
700 static void echo_move_back_col(struct tty_struct
*tty
)
702 mutex_lock(&tty
->echo_lock
);
704 add_echo_byte(ECHO_OP_START
, tty
);
705 add_echo_byte(ECHO_OP_MOVE_BACK_COL
, tty
);
707 mutex_unlock(&tty
->echo_lock
);
711 * echo_set_canon_col - add operation to set the canon column
712 * @tty: terminal device
714 * Add an operation to the echo buffer to set the canon column
715 * to the current column.
717 * Locking: echo_lock to protect the echo buffer
720 static void echo_set_canon_col(struct tty_struct
*tty
)
722 mutex_lock(&tty
->echo_lock
);
724 add_echo_byte(ECHO_OP_START
, tty
);
725 add_echo_byte(ECHO_OP_SET_CANON_COL
, tty
);
727 mutex_unlock(&tty
->echo_lock
);
731 * echo_erase_tab - add operation to erase a tab
732 * @num_chars: number of character columns already used
733 * @after_tab: true if num_chars starts after a previous tab
734 * @tty: terminal device
736 * Add an operation to the echo buffer to erase a tab.
738 * Called by the eraser function, which knows how many character
739 * columns have been used since either a previous tab or the start
740 * of input. This information will be used later, along with
741 * canon column (if applicable), to go back the correct number
744 * Locking: echo_lock to protect the echo buffer
747 static void echo_erase_tab(unsigned int num_chars
, int after_tab
,
748 struct tty_struct
*tty
)
750 mutex_lock(&tty
->echo_lock
);
752 add_echo_byte(ECHO_OP_START
, tty
);
753 add_echo_byte(ECHO_OP_ERASE_TAB
, tty
);
755 /* We only need to know this modulo 8 (tab spacing) */
758 /* Set the high bit as a flag if num_chars is after a previous tab */
762 add_echo_byte(num_chars
, tty
);
764 mutex_unlock(&tty
->echo_lock
);
768 * echo_char_raw - echo a character raw
769 * @c: unicode byte to echo
770 * @tty: terminal device
772 * Echo user input back onto the screen. This must be called only when
773 * L_ECHO(tty) is true. Called from the driver receive_buf path.
775 * This variant does not treat control characters specially.
777 * Locking: echo_lock to protect the echo buffer
780 static void echo_char_raw(unsigned char c
, struct tty_struct
*tty
)
782 mutex_lock(&tty
->echo_lock
);
784 if (c
== ECHO_OP_START
) {
785 add_echo_byte(ECHO_OP_START
, tty
);
786 add_echo_byte(ECHO_OP_START
, tty
);
788 add_echo_byte(c
, tty
);
791 mutex_unlock(&tty
->echo_lock
);
795 * echo_char - echo a character
796 * @c: unicode byte to echo
797 * @tty: terminal device
799 * Echo user input back onto the screen. This must be called only when
800 * L_ECHO(tty) is true. Called from the driver receive_buf path.
802 * This variant tags control characters to be possibly echoed as
803 * as "^X" (where X is the letter representing the control char).
805 * Locking: echo_lock to protect the echo buffer
808 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
810 mutex_lock(&tty
->echo_lock
);
812 if (c
== ECHO_OP_START
) {
813 add_echo_byte(ECHO_OP_START
, tty
);
814 add_echo_byte(ECHO_OP_START
, tty
);
816 if (iscntrl(c
) && c
!= '\t')
817 add_echo_byte(ECHO_OP_START
, tty
);
818 add_echo_byte(c
, tty
);
821 mutex_unlock(&tty
->echo_lock
);
825 * finish_erasing - complete erase
826 * @tty: tty doing the erase
829 static inline void finish_erasing(struct tty_struct
*tty
)
832 echo_char_raw('/', tty
);
838 * eraser - handle erase function
839 * @c: character input
840 * @tty: terminal device
842 * Perform erase and necessary output when an erase character is
843 * present in the stream from the driver layer. Handles the complexities
844 * of UTF-8 multibyte symbols.
846 * Locking: read_lock for tty buffers
849 static void eraser(unsigned char c
, struct tty_struct
*tty
)
851 enum { ERASE
, WERASE
, KILL
} kill_type
;
852 int head
, seen_alnums
, cnt
;
855 /* FIXME: locking needed ? */
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 /* FIXME: Locking ?? */
891 while (tty
->read_head
!= tty
->canon_head
) {
892 head
= tty
->read_head
;
894 /* erase a single possibly multibyte character */
896 head
= (head
- 1) & (N_TTY_BUF_SIZE
-1);
897 c
= tty
->read_buf
[head
];
898 } while (is_continuation(c
, tty
) && head
!= tty
->canon_head
);
900 /* do not partially erase */
901 if (is_continuation(c
, tty
))
904 if (kill_type
== WERASE
) {
905 /* Equivalent to BSD's ALTWERASE. */
906 if (isalnum(c
) || c
== '_')
908 else if (seen_alnums
)
911 cnt
= (tty
->read_head
- head
) & (N_TTY_BUF_SIZE
-1);
912 spin_lock_irqsave(&tty
->read_lock
, flags
);
913 tty
->read_head
= head
;
914 tty
->read_cnt
-= cnt
;
915 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
917 if (L_ECHOPRT(tty
)) {
919 echo_char_raw('\\', tty
);
922 /* if cnt > 1, output a multi-byte character */
925 head
= (head
+1) & (N_TTY_BUF_SIZE
-1);
926 echo_char_raw(tty
->read_buf
[head
], tty
);
927 echo_move_back_col(tty
);
929 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
930 echo_char(ERASE_CHAR(tty
), tty
);
931 } else if (c
== '\t') {
932 unsigned int num_chars
= 0;
934 unsigned long tail
= tty
->read_head
;
937 * Count the columns used for characters
938 * since the start of input or after a
940 * This info is used to go back the correct
943 while (tail
!= tty
->canon_head
) {
944 tail
= (tail
-1) & (N_TTY_BUF_SIZE
-1);
945 c
= tty
->read_buf
[tail
];
949 } else if (iscntrl(c
)) {
952 } else if (!is_continuation(c
, tty
)) {
956 echo_erase_tab(num_chars
, after_tab
, tty
);
958 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
959 echo_char_raw('\b', tty
);
960 echo_char_raw(' ', tty
);
961 echo_char_raw('\b', tty
);
963 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
964 echo_char_raw('\b', tty
);
965 echo_char_raw(' ', tty
);
966 echo_char_raw('\b', tty
);
970 if (kill_type
== ERASE
)
973 if (tty
->read_head
== tty
->canon_head
&& L_ECHO(tty
))
978 * isig - handle the ISIG optio
981 * @flush: force flush
983 * Called when a signal is being sent due to terminal input. This
984 * may caus terminal flushing to take place according to the termios
985 * settings and character used. Called from the driver receive_buf
986 * path so serialized.
988 * Locking: ctrl_lock, read_lock (both via flush buffer)
991 static inline void isig(int sig
, struct tty_struct
*tty
, int flush
)
994 kill_pgrp(tty
->pgrp
, sig
, 1);
995 if (flush
|| !L_NOFLSH(tty
)) {
996 n_tty_flush_buffer(tty
);
997 tty_driver_flush_buffer(tty
);
1002 * n_tty_receive_break - handle break
1005 * An RS232 break event has been hit in the incoming bitstream. This
1006 * can cause a variety of events depending upon the termios settings.
1008 * Called from the receive_buf path so single threaded.
1011 static inline void n_tty_receive_break(struct tty_struct
*tty
)
1015 if (I_BRKINT(tty
)) {
1016 isig(SIGINT
, tty
, 1);
1019 if (I_PARMRK(tty
)) {
1020 put_tty_queue('\377', tty
);
1021 put_tty_queue('\0', tty
);
1023 put_tty_queue('\0', tty
);
1024 wake_up_interruptible(&tty
->read_wait
);
1028 * n_tty_receive_overrun - handle overrun reporting
1031 * Data arrived faster than we could process it. While the tty
1032 * driver has flagged this the bits that were missed are gone
1035 * Called from the receive_buf path so single threaded. Does not
1036 * need locking as num_overrun and overrun_time are function
1040 static inline void n_tty_receive_overrun(struct tty_struct
*tty
)
1045 if (time_before(tty
->overrun_time
, jiffies
- HZ
) ||
1046 time_after(tty
->overrun_time
, jiffies
)) {
1047 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
1050 tty
->overrun_time
= jiffies
;
1051 tty
->num_overrun
= 0;
1056 * n_tty_receive_parity_error - error notifier
1057 * @tty: terminal device
1060 * Process a parity error and queue the right data to indicate
1061 * the error case if necessary. Locking as per n_tty_receive_buf.
1063 static inline void n_tty_receive_parity_error(struct tty_struct
*tty
,
1068 if (I_PARMRK(tty
)) {
1069 put_tty_queue('\377', tty
);
1070 put_tty_queue('\0', tty
);
1071 put_tty_queue(c
, tty
);
1072 } else if (I_INPCK(tty
))
1073 put_tty_queue('\0', tty
);
1075 put_tty_queue(c
, tty
);
1076 wake_up_interruptible(&tty
->read_wait
);
1080 * n_tty_receive_char - perform processing
1081 * @tty: terminal device
1084 * Process an individual character of input received from the driver.
1085 * This is serialized with respect to itself by the rules for the
1089 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
1091 unsigned long flags
;
1095 put_tty_queue(c
, tty
);
1101 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
1104 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) &&
1105 I_IXANY(tty
) && c
!= START_CHAR(tty
) && c
!= STOP_CHAR(tty
) &&
1106 c
!= INTR_CHAR(tty
) && c
!= QUIT_CHAR(tty
) && c
!= SUSP_CHAR(tty
)) {
1108 process_echoes(tty
);
1113 if (c
== START_CHAR(tty
)) {
1115 process_echoes(tty
);
1116 } else if (c
== STOP_CHAR(tty
))
1123 * If the previous character was LNEXT, or we know that this
1124 * character is not one of the characters that we'll have to
1125 * handle specially, do shortcut processing to speed things
1128 if (!test_bit(c
, tty
->process_char_map
) || tty
->lnext
) {
1130 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1131 if (tty
->read_cnt
>= (N_TTY_BUF_SIZE
- parmrk
- 1)) {
1132 /* beep if no space */
1134 process_output('\a', tty
);
1138 finish_erasing(tty
);
1139 /* Record the column of first canon char. */
1140 if (tty
->canon_head
== tty
->read_head
)
1141 echo_set_canon_col(tty
);
1143 process_echoes(tty
);
1146 put_tty_queue(c
, tty
);
1147 put_tty_queue(c
, tty
);
1152 if (c
== START_CHAR(tty
)) {
1154 process_echoes(tty
);
1157 if (c
== STOP_CHAR(tty
)) {
1166 if (c
== INTR_CHAR(tty
))
1169 if (c
== QUIT_CHAR(tty
))
1172 if (c
== SUSP_CHAR(tty
)) {
1175 * Note that we do not use isig() here because we want
1177 * 1) flush, 2) echo, 3) signal
1179 if (!L_NOFLSH(tty
)) {
1180 n_tty_flush_buffer(tty
);
1181 tty_driver_flush_buffer(tty
);
1187 process_echoes(tty
);
1190 kill_pgrp(tty
->pgrp
, signal
, 1);
1200 } else if (c
== '\n' && I_INLCR(tty
))
1204 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
1205 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
1207 process_echoes(tty
);
1210 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
1213 finish_erasing(tty
);
1214 if (L_ECHOCTL(tty
)) {
1215 echo_char_raw('^', tty
);
1216 echo_char_raw('\b', tty
);
1217 process_echoes(tty
);
1222 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
1224 unsigned long tail
= tty
->canon_head
;
1226 finish_erasing(tty
);
1228 echo_char_raw('\n', tty
);
1229 while (tail
!= tty
->read_head
) {
1230 echo_char(tty
->read_buf
[tail
], tty
);
1231 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
1233 process_echoes(tty
);
1237 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
) {
1239 process_output('\a', tty
);
1242 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
1243 echo_char_raw('\n', tty
);
1244 process_echoes(tty
);
1246 goto handle_newline
;
1248 if (c
== EOF_CHAR(tty
)) {
1249 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
)
1251 if (tty
->canon_head
!= tty
->read_head
)
1252 set_bit(TTY_PUSH
, &tty
->flags
);
1253 c
= __DISABLED_CHAR
;
1254 goto handle_newline
;
1256 if ((c
== EOL_CHAR(tty
)) ||
1257 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
1258 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
))
1260 if (tty
->read_cnt
>= (N_TTY_BUF_SIZE
- parmrk
)) {
1262 process_output('\a', tty
);
1266 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1269 /* Record the column of first canon char. */
1270 if (tty
->canon_head
== tty
->read_head
)
1271 echo_set_canon_col(tty
);
1273 process_echoes(tty
);
1276 * XXX does PARMRK doubling happen for
1277 * EOL_CHAR and EOL2_CHAR?
1280 put_tty_queue(c
, tty
);
1283 spin_lock_irqsave(&tty
->read_lock
, flags
);
1284 set_bit(tty
->read_head
, tty
->read_flags
);
1285 put_tty_queue_nolock(c
, tty
);
1286 tty
->canon_head
= tty
->read_head
;
1288 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1289 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1290 if (waitqueue_active(&tty
->read_wait
))
1291 wake_up_interruptible(&tty
->read_wait
);
1296 parmrk
= (c
== (unsigned char) '\377' && I_PARMRK(tty
)) ? 1 : 0;
1297 if (tty
->read_cnt
>= (N_TTY_BUF_SIZE
- parmrk
- 1)) {
1298 /* beep if no space */
1300 process_output('\a', tty
);
1304 finish_erasing(tty
);
1306 echo_char_raw('\n', tty
);
1308 /* Record the column of first canon char. */
1309 if (tty
->canon_head
== tty
->read_head
)
1310 echo_set_canon_col(tty
);
1313 process_echoes(tty
);
1317 put_tty_queue(c
, tty
);
1319 put_tty_queue(c
, tty
);
1324 * n_tty_write_wakeup - asynchronous I/O notifier
1327 * Required for the ptys, serial driver etc. since processes
1328 * that attach themselves to the master and rely on ASYNC
1329 * IO must be woken up
1332 static void n_tty_write_wakeup(struct tty_struct
*tty
)
1334 /* Write out any echoed characters that are still pending */
1335 process_echoes(tty
);
1337 if (tty
->fasync
&& test_and_clear_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
))
1338 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
1342 * n_tty_receive_buf - data receive
1343 * @tty: terminal device
1346 * @count: characters
1348 * Called by the terminal driver when a block of characters has
1349 * been received. This function must be called from soft contexts
1350 * not from interrupt context. The driver is responsible for making
1351 * calls one at a time and in order (or using flush_to_ldisc)
1354 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
1355 char *fp
, int count
)
1357 const unsigned char *p
;
1358 char *f
, flags
= TTY_NORMAL
;
1361 unsigned long cpuflags
;
1366 if (tty
->real_raw
) {
1367 spin_lock_irqsave(&tty
->read_lock
, cpuflags
);
1368 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
1369 N_TTY_BUF_SIZE
- tty
->read_head
);
1371 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
1372 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
1377 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
1378 N_TTY_BUF_SIZE
- tty
->read_head
);
1380 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
1381 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
1383 spin_unlock_irqrestore(&tty
->read_lock
, cpuflags
);
1385 for (i
= count
, p
= cp
, f
= fp
; i
; i
--, p
++) {
1390 n_tty_receive_char(tty
, *p
);
1393 n_tty_receive_break(tty
);
1397 n_tty_receive_parity_error(tty
, *p
);
1400 n_tty_receive_overrun(tty
);
1403 printk(KERN_ERR
"%s: unknown flag %d\n",
1404 tty_name(tty
, buf
), flags
);
1408 if (tty
->ops
->flush_chars
)
1409 tty
->ops
->flush_chars(tty
);
1412 n_tty_set_room(tty
);
1414 if (!tty
->icanon
&& (tty
->read_cnt
>= tty
->minimum_to_wake
)) {
1415 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
1416 if (waitqueue_active(&tty
->read_wait
))
1417 wake_up_interruptible(&tty
->read_wait
);
1421 * Check the remaining room for the input canonicalization
1422 * mode. We don't want to throttle the driver if we're in
1423 * canonical mode and don't have a newline yet!
1425 if (tty
->receive_room
< TTY_THRESHOLD_THROTTLE
)
1429 int is_ignored(int sig
)
1431 return (sigismember(¤t
->blocked
, sig
) ||
1432 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1436 * n_tty_set_termios - termios data changed
1438 * @old: previous data
1440 * Called by the tty layer when the user changes termios flags so
1441 * that the line discipline can plan ahead. This function cannot sleep
1442 * and is protected from re-entry by the tty layer. The user is
1443 * guaranteed that this function will not be re-entered or in progress
1444 * when the ldisc is closed.
1446 * Locking: Caller holds tty->termios_mutex
1449 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1451 int canon_change
= 1;
1455 canon_change
= (old
->c_lflag
^ tty
->termios
->c_lflag
) & ICANON
;
1457 memset(&tty
->read_flags
, 0, sizeof tty
->read_flags
);
1458 tty
->canon_head
= tty
->read_tail
;
1459 tty
->canon_data
= 0;
1463 if (canon_change
&& !L_ICANON(tty
) && tty
->read_cnt
)
1464 wake_up_interruptible(&tty
->read_wait
);
1466 tty
->icanon
= (L_ICANON(tty
) != 0);
1467 if (test_bit(TTY_HW_COOK_IN
, &tty
->flags
)) {
1470 n_tty_set_room(tty
);
1473 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1474 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1475 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1477 memset(tty
->process_char_map
, 0, 256/8);
1479 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1480 set_bit('\r', tty
->process_char_map
);
1482 set_bit('\n', tty
->process_char_map
);
1484 if (L_ICANON(tty
)) {
1485 set_bit(ERASE_CHAR(tty
), tty
->process_char_map
);
1486 set_bit(KILL_CHAR(tty
), tty
->process_char_map
);
1487 set_bit(EOF_CHAR(tty
), tty
->process_char_map
);
1488 set_bit('\n', tty
->process_char_map
);
1489 set_bit(EOL_CHAR(tty
), tty
->process_char_map
);
1490 if (L_IEXTEN(tty
)) {
1491 set_bit(WERASE_CHAR(tty
),
1492 tty
->process_char_map
);
1493 set_bit(LNEXT_CHAR(tty
),
1494 tty
->process_char_map
);
1495 set_bit(EOL2_CHAR(tty
),
1496 tty
->process_char_map
);
1498 set_bit(REPRINT_CHAR(tty
),
1499 tty
->process_char_map
);
1503 set_bit(START_CHAR(tty
), tty
->process_char_map
);
1504 set_bit(STOP_CHAR(tty
), tty
->process_char_map
);
1507 set_bit(INTR_CHAR(tty
), tty
->process_char_map
);
1508 set_bit(QUIT_CHAR(tty
), tty
->process_char_map
);
1509 set_bit(SUSP_CHAR(tty
), tty
->process_char_map
);
1511 clear_bit(__DISABLED_CHAR
, tty
->process_char_map
);
1516 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1517 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1518 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1523 n_tty_set_room(tty
);
1524 /* The termios change make the tty ready for I/O */
1525 wake_up_interruptible(&tty
->write_wait
);
1526 wake_up_interruptible(&tty
->read_wait
);
1530 * n_tty_close - close the ldisc for this tty
1533 * Called from the terminal layer when this line discipline is
1534 * being shut down, either because of a close or becsuse of a
1535 * discipline change. The function will not be called while other
1536 * ldisc methods are in progress.
1539 static void n_tty_close(struct tty_struct
*tty
)
1541 n_tty_flush_buffer(tty
);
1542 if (tty
->read_buf
) {
1543 kfree(tty
->read_buf
);
1544 tty
->read_buf
= NULL
;
1546 if (tty
->echo_buf
) {
1547 kfree(tty
->echo_buf
);
1548 tty
->echo_buf
= NULL
;
1553 * n_tty_open - open an ldisc
1554 * @tty: terminal to open
1556 * Called when this line discipline is being attached to the
1557 * terminal device. Can sleep. Called serialized so that no
1558 * other events will occur in parallel. No further open will occur
1562 static int n_tty_open(struct tty_struct
*tty
)
1567 /* These are ugly. Currently a malloc failure here can panic */
1568 if (!tty
->read_buf
) {
1569 tty
->read_buf
= kzalloc(N_TTY_BUF_SIZE
, GFP_KERNEL
);
1573 if (!tty
->echo_buf
) {
1574 tty
->echo_buf
= kzalloc(N_TTY_BUF_SIZE
, GFP_KERNEL
);
1579 reset_buffer_flags(tty
);
1581 n_tty_set_termios(tty
, NULL
);
1582 tty
->minimum_to_wake
= 1;
1587 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1590 if (tty
->canon_data
)
1592 } else if (tty
->read_cnt
>= (amt
? amt
: 1))
1599 * copy_from_read_buf - copy read data directly
1600 * @tty: terminal device
1604 * Helper function to speed up n_tty_read. It is only called when
1605 * ICANON is off; it copies characters straight from the tty queue to
1606 * user space directly. It can be profitably called twice; once to
1607 * drain the space from the tail pointer to the (physical) end of the
1608 * buffer, and once to drain the space from the (physical) beginning of
1609 * the buffer to head pointer.
1611 * Called under the tty->atomic_read_lock sem
1615 static int copy_from_read_buf(struct tty_struct
*tty
,
1616 unsigned char __user
**b
,
1622 unsigned long flags
;
1625 spin_lock_irqsave(&tty
->read_lock
, flags
);
1626 n
= min(tty
->read_cnt
, N_TTY_BUF_SIZE
- tty
->read_tail
);
1628 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1630 retval
= copy_to_user(*b
, &tty
->read_buf
[tty
->read_tail
], n
);
1632 tty_audit_add_data(tty
, &tty
->read_buf
[tty
->read_tail
], n
);
1633 spin_lock_irqsave(&tty
->read_lock
, flags
);
1634 tty
->read_tail
= (tty
->read_tail
+ n
) & (N_TTY_BUF_SIZE
-1);
1636 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1643 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
1647 * job_control - check job control
1649 * @file: file handle
1651 * Perform job control management checks on this file/tty descriptor
1652 * and if appropriate send any needed signals and return a negative
1653 * error code if action should be taken.
1656 * Locking: None - redirected write test is safe, testing
1657 * current->signal should possibly lock current->sighand
1661 static int job_control(struct tty_struct
*tty
, struct file
*file
)
1663 /* Job control check -- must be done at start and after
1664 every sleep (POSIX.1 7.1.1.4). */
1665 /* NOTE: not yet done after every sleep pending a thorough
1666 check of the logic of this change. -- jlc */
1667 /* don't stop on /dev/console */
1668 if (file
->f_op
->write
!= redirected_tty_write
&&
1669 current
->signal
->tty
== tty
) {
1671 printk(KERN_ERR
"n_tty_read: no tty->pgrp!\n");
1672 else if (task_pgrp(current
) != tty
->pgrp
) {
1673 if (is_ignored(SIGTTIN
) ||
1674 is_current_pgrp_orphaned())
1676 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
1677 set_thread_flag(TIF_SIGPENDING
);
1678 return -ERESTARTSYS
;
1686 * n_tty_read - read function for tty
1688 * @file: file object
1689 * @buf: userspace buffer pointer
1692 * Perform reads for the line discipline. We are guaranteed that the
1693 * line discipline will not be closed under us but we may get multiple
1694 * parallel readers and must handle this ourselves. We may also get
1695 * a hangup. Always called in user context, may sleep.
1697 * This code must be sure never to sleep through a hangup.
1700 static ssize_t
n_tty_read(struct tty_struct
*tty
, struct file
*file
,
1701 unsigned char __user
*buf
, size_t nr
)
1703 unsigned char __user
*b
= buf
;
1704 DECLARE_WAITQUEUE(wait
, current
);
1710 unsigned long flags
;
1715 BUG_ON(!tty
->read_buf
);
1717 c
= job_control(tty
, file
);
1722 timeout
= MAX_SCHEDULE_TIMEOUT
;
1724 time
= (HZ
/ 10) * TIME_CHAR(tty
);
1725 minimum
= MIN_CHAR(tty
);
1728 tty
->minimum_to_wake
= 1;
1729 else if (!waitqueue_active(&tty
->read_wait
) ||
1730 (tty
->minimum_to_wake
> minimum
))
1731 tty
->minimum_to_wake
= minimum
;
1738 tty
->minimum_to_wake
= minimum
= 1;
1743 * Internal serialization of reads.
1745 if (file
->f_flags
& O_NONBLOCK
) {
1746 if (!mutex_trylock(&tty
->atomic_read_lock
))
1749 if (mutex_lock_interruptible(&tty
->atomic_read_lock
))
1750 return -ERESTARTSYS
;
1752 packet
= tty
->packet
;
1754 add_wait_queue(&tty
->read_wait
, &wait
);
1756 /* First test for status change. */
1757 if (packet
&& tty
->link
->ctrl_status
) {
1761 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
1762 cs
= tty
->link
->ctrl_status
;
1763 tty
->link
->ctrl_status
= 0;
1764 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
1765 if (tty_put_user(tty
, cs
, b
++)) {
1773 /* This statement must be first before checking for input
1774 so that any interrupt will set the state back to
1776 set_current_state(TASK_INTERRUPTIBLE
);
1778 if (((minimum
- (b
- buf
)) < tty
->minimum_to_wake
) &&
1779 ((minimum
- (b
- buf
)) >= 1))
1780 tty
->minimum_to_wake
= (minimum
- (b
- buf
));
1782 if (!input_available_p(tty
, 0)) {
1783 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
1787 if (tty_hung_up_p(file
))
1791 if (file
->f_flags
& O_NONBLOCK
) {
1795 if (signal_pending(current
)) {
1796 retval
= -ERESTARTSYS
;
1799 /* FIXME: does n_tty_set_room need locking ? */
1800 n_tty_set_room(tty
);
1801 timeout
= schedule_timeout(timeout
);
1804 __set_current_state(TASK_RUNNING
);
1806 /* Deal with packet mode. */
1807 if (packet
&& b
== buf
) {
1808 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
1817 /* N.B. avoid overrun if nr == 0 */
1818 while (nr
&& tty
->read_cnt
) {
1821 eol
= test_and_clear_bit(tty
->read_tail
,
1823 c
= tty
->read_buf
[tty
->read_tail
];
1824 spin_lock_irqsave(&tty
->read_lock
, flags
);
1825 tty
->read_tail
= ((tty
->read_tail
+1) &
1826 (N_TTY_BUF_SIZE
-1));
1829 /* this test should be redundant:
1830 * we shouldn't be reading data if
1833 if (--tty
->canon_data
< 0)
1834 tty
->canon_data
= 0;
1836 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1838 if (!eol
|| (c
!= __DISABLED_CHAR
)) {
1839 if (tty_put_user(tty
, c
, b
++)) {
1847 tty_audit_push(tty
);
1855 /* The copy function takes the read lock and handles
1856 locking internally for this case */
1857 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
1858 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
1865 /* If there is enough space in the read buffer now, let the
1866 * low-level driver know. We use n_tty_chars_in_buffer() to
1867 * check the buffer, as it now knows about canonical mode.
1868 * Otherwise, if the driver is throttled and the line is
1869 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1870 * we won't get any more characters.
1872 if (n_tty_chars_in_buffer(tty
) <= TTY_THRESHOLD_UNTHROTTLE
) {
1873 n_tty_set_room(tty
);
1874 check_unthrottle(tty
);
1877 if (b
- buf
>= minimum
)
1882 mutex_unlock(&tty
->atomic_read_lock
);
1883 remove_wait_queue(&tty
->read_wait
, &wait
);
1885 if (!waitqueue_active(&tty
->read_wait
))
1886 tty
->minimum_to_wake
= minimum
;
1888 __set_current_state(TASK_RUNNING
);
1893 clear_bit(TTY_PUSH
, &tty
->flags
);
1894 } else if (test_and_clear_bit(TTY_PUSH
, &tty
->flags
))
1897 n_tty_set_room(tty
);
1902 * n_tty_write - write function for tty
1904 * @file: file object
1905 * @buf: userspace buffer pointer
1908 * Write function of the terminal device. This is serialized with
1909 * respect to other write callers but not to termios changes, reads
1910 * and other such events. Since the receive code will echo characters,
1911 * thus calling driver write methods, the output_lock is used in
1912 * the output processing functions called here as well as in the
1913 * echo processing function to protect the column state and space
1914 * left in the buffer.
1916 * This code must be sure never to sleep through a hangup.
1918 * Locking: output_lock to protect column state and space left
1919 * (note that the process_output*() functions take this
1923 static ssize_t
n_tty_write(struct tty_struct
*tty
, struct file
*file
,
1924 const unsigned char *buf
, size_t nr
)
1926 const unsigned char *b
= buf
;
1927 DECLARE_WAITQUEUE(wait
, current
);
1931 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1932 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
1933 retval
= tty_check_change(tty
);
1938 /* Write out any echoed characters that are still pending */
1939 process_echoes(tty
);
1941 add_wait_queue(&tty
->write_wait
, &wait
);
1943 set_current_state(TASK_INTERRUPTIBLE
);
1944 if (signal_pending(current
)) {
1945 retval
= -ERESTARTSYS
;
1948 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
1952 if (O_OPOST(tty
) && !(test_bit(TTY_HW_COOK_OUT
, &tty
->flags
))) {
1954 ssize_t num
= process_output_block(tty
, b
, nr
);
1966 if (process_output(c
, tty
) < 0)
1970 if (tty
->ops
->flush_chars
)
1971 tty
->ops
->flush_chars(tty
);
1974 c
= tty
->ops
->write(tty
, b
, nr
);
1987 if (file
->f_flags
& O_NONBLOCK
) {
1994 __set_current_state(TASK_RUNNING
);
1995 remove_wait_queue(&tty
->write_wait
, &wait
);
1996 if (b
- buf
!= nr
&& tty
->fasync
)
1997 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
1998 return (b
- buf
) ? b
- buf
: retval
;
2002 * n_tty_poll - poll method for N_TTY
2003 * @tty: terminal device
2004 * @file: file accessing it
2007 * Called when the line discipline is asked to poll() for data or
2008 * for special events. This code is not serialized with respect to
2009 * other events save open/close.
2011 * This code must be sure never to sleep through a hangup.
2012 * Called without the kernel lock held - fine
2015 static unsigned int n_tty_poll(struct tty_struct
*tty
, struct file
*file
,
2018 unsigned int mask
= 0;
2020 poll_wait(file
, &tty
->read_wait
, wait
);
2021 poll_wait(file
, &tty
->write_wait
, wait
);
2022 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
2023 mask
|= POLLIN
| POLLRDNORM
;
2024 if (tty
->packet
&& tty
->link
->ctrl_status
)
2025 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
2026 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
2028 if (tty_hung_up_p(file
))
2030 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
2031 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
2032 tty
->minimum_to_wake
= MIN_CHAR(tty
);
2034 tty
->minimum_to_wake
= 1;
2036 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
2037 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
2038 tty_write_room(tty
) > 0)
2039 mask
|= POLLOUT
| POLLWRNORM
;
2043 static unsigned long inq_canon(struct tty_struct
*tty
)
2047 if (!tty
->canon_data
)
2049 head
= tty
->canon_head
;
2050 tail
= tty
->read_tail
;
2051 nr
= (head
- tail
) & (N_TTY_BUF_SIZE
-1);
2052 /* Skip EOF-chars.. */
2053 while (head
!= tail
) {
2054 if (test_bit(tail
, tty
->read_flags
) &&
2055 tty
->read_buf
[tail
] == __DISABLED_CHAR
)
2057 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
2062 static int n_tty_ioctl(struct tty_struct
*tty
, struct file
*file
,
2063 unsigned int cmd
, unsigned long arg
)
2069 return put_user(tty_chars_in_buffer(tty
), (int __user
*) arg
);
2071 /* FIXME: Locking */
2072 retval
= tty
->read_cnt
;
2074 retval
= inq_canon(tty
);
2075 return put_user(retval
, (unsigned int __user
*) arg
);
2077 return n_tty_ioctl_helper(tty
, file
, cmd
, arg
);
2081 struct tty_ldisc_ops tty_ldisc_N_TTY
= {
2082 .magic
= TTY_LDISC_MAGIC
,
2085 .close
= n_tty_close
,
2086 .flush_buffer
= n_tty_flush_buffer
,
2087 .chars_in_buffer
= n_tty_chars_in_buffer
,
2089 .write
= n_tty_write
,
2090 .ioctl
= n_tty_ioctl
,
2091 .set_termios
= n_tty_set_termios
,
2093 .receive_buf
= n_tty_receive_buf
,
2094 .write_wakeup
= n_tty_write_wakeup