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 write_chan 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>
51 #include <asm/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
65 static inline unsigned char *alloc_buf(void)
67 gfp_t prio
= in_interrupt() ? GFP_ATOMIC
: GFP_KERNEL
;
69 if (PAGE_SIZE
!= N_TTY_BUF_SIZE
)
70 return kmalloc(N_TTY_BUF_SIZE
, prio
);
72 return (unsigned char *)__get_free_page(prio
);
75 static inline void free_buf(unsigned char *buf
)
77 if (PAGE_SIZE
!= N_TTY_BUF_SIZE
)
80 free_page((unsigned long) buf
);
83 static inline int tty_put_user(struct tty_struct
*tty
, unsigned char x
,
84 unsigned char __user
*ptr
)
86 tty_audit_add_data(tty
, &x
, 1);
87 return put_user(x
, ptr
);
91 * n_tty_set__room - receive space
94 * Called by the driver to find out how much data it is
95 * permitted to feed to the line discipline without any being lost
96 * and thus to manage flow control. Not serialized. Answers for the
100 static void n_tty_set_room(struct tty_struct
*tty
)
102 int left
= N_TTY_BUF_SIZE
- tty
->read_cnt
- 1;
105 * If we are doing input canonicalization, and there are no
106 * pending newlines, let characters through without limit, so
107 * that erase characters will be handled. Other excess
108 * characters will be beeped.
111 left
= tty
->icanon
&& !tty
->canon_data
;
112 tty
->receive_room
= left
;
115 static void put_tty_queue_nolock(unsigned char c
, struct tty_struct
*tty
)
117 if (tty
->read_cnt
< N_TTY_BUF_SIZE
) {
118 tty
->read_buf
[tty
->read_head
] = c
;
119 tty
->read_head
= (tty
->read_head
+ 1) & (N_TTY_BUF_SIZE
-1);
124 static void put_tty_queue(unsigned char c
, struct tty_struct
*tty
)
128 * The problem of stomping on the buffers ends here.
129 * Why didn't anyone see this one coming? --AJK
131 spin_lock_irqsave(&tty
->read_lock
, flags
);
132 put_tty_queue_nolock(c
, tty
);
133 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
137 * check_unthrottle - allow new receive data
140 * Check whether to call the driver.unthrottle function.
141 * We test the TTY_THROTTLED bit first so that it always
142 * indicates the current state. The decision about whether
143 * it is worth allowing more input has been taken by the caller.
144 * Can sleep, may be called under the atomic_read_lock mutex but
145 * this is not guaranteed.
148 static void check_unthrottle(struct tty_struct
* tty
)
151 test_and_clear_bit(TTY_THROTTLED
, &tty
->flags
) &&
152 tty
->driver
->unthrottle
)
153 tty
->driver
->unthrottle(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 static void reset_buffer_flags(struct tty_struct
*tty
)
168 spin_lock_irqsave(&tty
->read_lock
, flags
);
169 tty
->read_head
= tty
->read_tail
= tty
->read_cnt
= 0;
170 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
171 tty
->canon_head
= tty
->canon_data
= tty
->erasing
= 0;
172 memset(&tty
->read_flags
, 0, sizeof tty
->read_flags
);
174 check_unthrottle(tty
);
178 * n_tty_flush_buffer - clean input queue
179 * @tty: terminal device
181 * Flush the input buffer. Called when the line discipline is
182 * being closed, when the tty layer wants the buffer flushed (eg
183 * at hangup) or when the N_TTY line discipline internally has to
184 * clean the pending queue (for example some signals).
186 * FIXME: tty->ctrl_status is not spinlocked and relies on
187 * lock_kernel() still.
190 static void n_tty_flush_buffer(struct tty_struct
* tty
)
192 /* clear everything and unthrottle the driver */
193 reset_buffer_flags(tty
);
198 if (tty
->link
->packet
) {
199 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
200 wake_up_interruptible(&tty
->link
->read_wait
);
205 * n_tty_chars_in_buffer - report available bytes
208 * Report the number of characters buffered to be delivered to user
209 * at this instant in time.
212 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
217 spin_lock_irqsave(&tty
->read_lock
, flags
);
220 } else if (tty
->canon_data
) {
221 n
= (tty
->canon_head
> tty
->read_tail
) ?
222 tty
->canon_head
- tty
->read_tail
:
223 tty
->canon_head
+ (N_TTY_BUF_SIZE
- tty
->read_tail
);
225 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
230 * is_utf8_continuation - utf8 multibyte check
233 * Returns true if the utf8 character 'c' is a multibyte continuation
234 * character. We use this to correctly compute the on screen size
235 * of the character when printing
238 static inline int is_utf8_continuation(unsigned char c
)
240 return (c
& 0xc0) == 0x80;
244 * is_continuation - multibyte check
247 * Returns true if the utf8 character 'c' is a multibyte continuation
248 * character and the terminal is in unicode mode.
251 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
253 return I_IUTF8(tty
) && is_utf8_continuation(c
);
257 * opost - output post processor
258 * @c: character (or partial unicode symbol)
259 * @tty: terminal device
261 * Perform OPOST processing. Returns -1 when the output device is
262 * full and the character must be retried. Note that Linux currently
263 * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
264 * relevant in the world today. If you ever need them, add them here.
266 * Called from both the receive and transmit sides and can be called
267 * re-entrantly. Relies on lock_kernel() still.
270 static int opost(unsigned char c
, struct tty_struct
*tty
)
274 space
= tty
->driver
->write_room(tty
);
286 tty
->driver
->put_char(tty
, '\r');
289 tty
->canon_column
= tty
->column
;
292 if (O_ONOCR(tty
) && tty
->column
== 0)
297 tty
->canon_column
= tty
->column
= 0;
300 tty
->canon_column
= tty
->column
= 0;
303 spaces
= 8 - (tty
->column
& 7);
304 if (O_TABDLY(tty
) == XTABS
) {
307 tty
->column
+= spaces
;
308 tty
->driver
->write(tty
, " ", spaces
);
311 tty
->column
+= spaces
;
320 if (!iscntrl(c
) && !is_continuation(c
, tty
))
325 tty
->driver
->put_char(tty
, c
);
330 * opost_block - block postprocess
331 * @tty: terminal device
332 * @inbuf: user buffer
333 * @nr: number of bytes
335 * This path is used to speed up block console writes, among other
336 * things when processing blocks of output data. It handles only
337 * the simple cases normally found and helps to generate blocks of
338 * symbols for the console driver and thus improve performance.
340 * Called from write_chan under the tty layer write lock.
343 static ssize_t
opost_block(struct tty_struct
* tty
,
344 const unsigned char * buf
, unsigned int nr
)
348 const unsigned char *cp
;
350 space
= tty
->driver
->write_room(tty
);
356 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
363 tty
->canon_column
= tty
->column
;
366 if (O_ONOCR(tty
) && tty
->column
== 0)
370 tty
->canon_column
= tty
->column
= 0;
387 if (tty
->driver
->flush_chars
)
388 tty
->driver
->flush_chars(tty
);
389 i
= tty
->driver
->write(tty
, buf
, i
);
395 * put_char - write character to driver
396 * @c: character (or part of unicode symbol)
397 * @tty: terminal device
399 * Queue a byte to the driver layer for output
402 static inline void put_char(unsigned char c
, struct tty_struct
*tty
)
404 tty
->driver
->put_char(tty
, c
);
408 * echo_char - echo characters
409 * @c: unicode byte to echo
410 * @tty: terminal device
412 * Echo user input back onto the screen. This must be called only when
413 * L_ECHO(tty) is true. Called from the driver receive_buf path.
416 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
418 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t') {
420 put_char(c
^ 0100, tty
);
426 static inline void finish_erasing(struct tty_struct
*tty
)
436 * eraser - handle erase function
437 * @c: character input
438 * @tty: terminal device
440 * Perform erase and neccessary output when an erase character is
441 * present in the stream from the driver layer. Handles the complexities
442 * of UTF-8 multibyte symbols.
445 static void eraser(unsigned char c
, struct tty_struct
*tty
)
447 enum { ERASE
, WERASE
, KILL
} kill_type
;
448 int head
, seen_alnums
, cnt
;
451 if (tty
->read_head
== tty
->canon_head
) {
452 /* opost('\a', tty); */ /* what do you think? */
455 if (c
== ERASE_CHAR(tty
))
457 else if (c
== WERASE_CHAR(tty
))
461 spin_lock_irqsave(&tty
->read_lock
, flags
);
462 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
463 (N_TTY_BUF_SIZE
- 1));
464 tty
->read_head
= tty
->canon_head
;
465 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
468 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
469 spin_lock_irqsave(&tty
->read_lock
, flags
);
470 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
471 (N_TTY_BUF_SIZE
- 1));
472 tty
->read_head
= tty
->canon_head
;
473 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
475 echo_char(KILL_CHAR(tty
), tty
);
476 /* Add a newline if ECHOK is on and ECHOKE is off. */
485 while (tty
->read_head
!= tty
->canon_head
) {
486 head
= tty
->read_head
;
488 /* erase a single possibly multibyte character */
490 head
= (head
- 1) & (N_TTY_BUF_SIZE
-1);
491 c
= tty
->read_buf
[head
];
492 } while (is_continuation(c
, tty
) && head
!= tty
->canon_head
);
494 /* do not partially erase */
495 if (is_continuation(c
, tty
))
498 if (kill_type
== WERASE
) {
499 /* Equivalent to BSD's ALTWERASE. */
500 if (isalnum(c
) || c
== '_')
502 else if (seen_alnums
)
505 cnt
= (tty
->read_head
- head
) & (N_TTY_BUF_SIZE
-1);
506 spin_lock_irqsave(&tty
->read_lock
, flags
);
507 tty
->read_head
= head
;
508 tty
->read_cnt
-= cnt
;
509 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
511 if (L_ECHOPRT(tty
)) {
517 /* if cnt > 1, output a multi-byte character */
520 head
= (head
+1) & (N_TTY_BUF_SIZE
-1);
521 put_char(tty
->read_buf
[head
], tty
);
523 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
524 echo_char(ERASE_CHAR(tty
), tty
);
525 } else if (c
== '\t') {
526 unsigned int col
= tty
->canon_column
;
527 unsigned long tail
= tty
->canon_head
;
529 /* Find the column of the last char. */
530 while (tail
!= tty
->read_head
) {
531 c
= tty
->read_buf
[tail
];
534 else if (iscntrl(c
)) {
537 } else if (!is_continuation(c
, tty
))
539 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
542 /* should never happen */
543 if (tty
->column
> 0x80000000)
546 /* Now backup to that column. */
547 while (tty
->column
> col
) {
548 /* Can't use opost here. */
554 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
561 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
570 if (kill_type
== ERASE
)
573 if (tty
->read_head
== tty
->canon_head
)
578 * isig - handle the ISIG optio
581 * @flush: force flush
583 * Called when a signal is being sent due to terminal input. This
584 * may caus terminal flushing to take place according to the termios
585 * settings and character used. Called from the driver receive_buf
586 * path so serialized.
589 static inline void isig(int sig
, struct tty_struct
*tty
, int flush
)
592 kill_pgrp(tty
->pgrp
, sig
, 1);
593 if (flush
|| !L_NOFLSH(tty
)) {
594 n_tty_flush_buffer(tty
);
595 if (tty
->driver
->flush_buffer
)
596 tty
->driver
->flush_buffer(tty
);
601 * n_tty_receive_break - handle break
604 * An RS232 break event has been hit in the incoming bitstream. This
605 * can cause a variety of events depending upon the termios settings.
607 * Called from the receive_buf path so single threaded.
610 static inline void n_tty_receive_break(struct tty_struct
*tty
)
615 isig(SIGINT
, tty
, 1);
619 put_tty_queue('\377', tty
);
620 put_tty_queue('\0', tty
);
622 put_tty_queue('\0', tty
);
623 wake_up_interruptible(&tty
->read_wait
);
627 * n_tty_receive_overrun - handle overrun reporting
630 * Data arrived faster than we could process it. While the tty
631 * driver has flagged this the bits that were missed are gone
634 * Called from the receive_buf path so single threaded. Does not
635 * need locking as num_overrun and overrun_time are function
639 static inline void n_tty_receive_overrun(struct tty_struct
*tty
)
644 if (time_before(tty
->overrun_time
, jiffies
- HZ
) ||
645 time_after(tty
->overrun_time
, jiffies
)) {
646 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
649 tty
->overrun_time
= jiffies
;
650 tty
->num_overrun
= 0;
655 * n_tty_receive_parity_error - error notifier
656 * @tty: terminal device
659 * Process a parity error and queue the right data to indicate
660 * the error case if neccessary. Locking as per n_tty_receive_buf.
662 static inline void n_tty_receive_parity_error(struct tty_struct
*tty
,
669 put_tty_queue('\377', tty
);
670 put_tty_queue('\0', tty
);
671 put_tty_queue(c
, tty
);
672 } else if (I_INPCK(tty
))
673 put_tty_queue('\0', tty
);
675 put_tty_queue(c
, tty
);
676 wake_up_interruptible(&tty
->read_wait
);
680 * n_tty_receive_char - perform processing
681 * @tty: terminal device
684 * Process an individual character of input received from the driver.
685 * This is serialized with respect to itself by the rules for the
689 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
694 put_tty_queue(c
, tty
);
698 if (tty
->stopped
&& !tty
->flow_stopped
&&
699 I_IXON(tty
) && I_IXANY(tty
)) {
706 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
711 if (c
== START_CHAR(tty
))
713 else if (c
== STOP_CHAR(tty
))
720 * If the previous character was LNEXT, or we know that this
721 * character is not one of the characters that we'll have to
722 * handle specially, do shortcut processing to speed things
725 if (!test_bit(c
, tty
->process_char_map
) || tty
->lnext
) {
729 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1) {
730 put_char('\a', tty
); /* beep if no space */
733 /* Record the column of first canon char. */
734 if (tty
->canon_head
== tty
->read_head
)
735 tty
->canon_column
= tty
->column
;
738 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
739 put_tty_queue(c
, tty
);
740 put_tty_queue(c
, tty
);
749 } else if (c
== '\n' && I_INLCR(tty
))
752 if (c
== START_CHAR(tty
)) {
756 if (c
== STOP_CHAR(tty
)) {
764 if (c
== INTR_CHAR(tty
))
767 if (c
== QUIT_CHAR(tty
))
770 if (c
== SUSP_CHAR(tty
)) {
772 isig(signal
, tty
, 0);
777 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
778 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
782 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
786 if (L_ECHOCTL(tty
)) {
793 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
795 unsigned long tail
= tty
->canon_head
;
800 while (tail
!= tty
->read_head
) {
801 echo_char(tty
->read_buf
[tail
], tty
);
802 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
807 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
808 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1)
814 if (c
== EOF_CHAR(tty
)) {
815 if (tty
->canon_head
!= tty
->read_head
)
816 set_bit(TTY_PUSH
, &tty
->flags
);
820 if ((c
== EOL_CHAR(tty
)) ||
821 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
823 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
826 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1)
828 /* Record the column of first canon char. */
829 if (tty
->canon_head
== tty
->read_head
)
830 tty
->canon_column
= tty
->column
;
834 * XXX does PARMRK doubling happen for
835 * EOL_CHAR and EOL2_CHAR?
837 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
838 put_tty_queue(c
, tty
);
841 spin_lock_irqsave(&tty
->read_lock
, flags
);
842 set_bit(tty
->read_head
, tty
->read_flags
);
843 put_tty_queue_nolock(c
, tty
);
844 tty
->canon_head
= tty
->read_head
;
846 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
847 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
848 if (waitqueue_active(&tty
->read_wait
))
849 wake_up_interruptible(&tty
->read_wait
);
856 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1) {
857 put_char('\a', tty
); /* beep if no space */
863 /* Record the column of first canon char. */
864 if (tty
->canon_head
== tty
->read_head
)
865 tty
->canon_column
= tty
->column
;
870 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
871 put_tty_queue(c
, tty
);
873 put_tty_queue(c
, tty
);
878 * n_tty_write_wakeup - asynchronous I/O notifier
881 * Required for the ptys, serial driver etc. since processes
882 * that attach themselves to the master and rely on ASYNC
883 * IO must be woken up
886 static void n_tty_write_wakeup(struct tty_struct
*tty
)
890 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
891 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
897 * n_tty_receive_buf - data receive
898 * @tty: terminal device
903 * Called by the terminal driver when a block of characters has
904 * been received. This function must be called from soft contexts
905 * not from interrupt context. The driver is responsible for making
906 * calls one at a time and in order (or using flush_to_ldisc)
909 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
912 const unsigned char *p
;
913 char *f
, flags
= TTY_NORMAL
;
916 unsigned long cpuflags
;
922 spin_lock_irqsave(&tty
->read_lock
, cpuflags
);
923 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
924 N_TTY_BUF_SIZE
- tty
->read_head
);
926 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
927 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
932 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
933 N_TTY_BUF_SIZE
- tty
->read_head
);
935 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
936 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
938 spin_unlock_irqrestore(&tty
->read_lock
, cpuflags
);
940 for (i
=count
, p
= cp
, f
= fp
; i
; i
--, p
++) {
945 n_tty_receive_char(tty
, *p
);
948 n_tty_receive_break(tty
);
952 n_tty_receive_parity_error(tty
, *p
);
955 n_tty_receive_overrun(tty
);
958 printk("%s: unknown flag %d\n",
959 tty_name(tty
, buf
), flags
);
963 if (tty
->driver
->flush_chars
)
964 tty
->driver
->flush_chars(tty
);
969 if (!tty
->icanon
&& (tty
->read_cnt
>= tty
->minimum_to_wake
)) {
970 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
971 if (waitqueue_active(&tty
->read_wait
))
972 wake_up_interruptible(&tty
->read_wait
);
976 * Check the remaining room for the input canonicalization
977 * mode. We don't want to throttle the driver if we're in
978 * canonical mode and don't have a newline yet!
980 if (tty
->receive_room
< TTY_THRESHOLD_THROTTLE
) {
981 /* check TTY_THROTTLED first so it indicates our state */
982 if (!test_and_set_bit(TTY_THROTTLED
, &tty
->flags
) &&
983 tty
->driver
->throttle
)
984 tty
->driver
->throttle(tty
);
988 int is_ignored(int sig
)
990 return (sigismember(¤t
->blocked
, sig
) ||
991 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
995 * n_tty_set_termios - termios data changed
997 * @old: previous data
999 * Called by the tty layer when the user changes termios flags so
1000 * that the line discipline can plan ahead. This function cannot sleep
1001 * and is protected from re-entry by the tty layer. The user is
1002 * guaranteed that this function will not be re-entered or in progress
1003 * when the ldisc is closed.
1006 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
* old
)
1011 tty
->icanon
= (L_ICANON(tty
) != 0);
1012 if (test_bit(TTY_HW_COOK_IN
, &tty
->flags
)) {
1015 n_tty_set_room(tty
);
1018 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1019 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1020 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1022 memset(tty
->process_char_map
, 0, 256/8);
1024 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1025 set_bit('\r', tty
->process_char_map
);
1027 set_bit('\n', tty
->process_char_map
);
1029 if (L_ICANON(tty
)) {
1030 set_bit(ERASE_CHAR(tty
), tty
->process_char_map
);
1031 set_bit(KILL_CHAR(tty
), tty
->process_char_map
);
1032 set_bit(EOF_CHAR(tty
), tty
->process_char_map
);
1033 set_bit('\n', tty
->process_char_map
);
1034 set_bit(EOL_CHAR(tty
), tty
->process_char_map
);
1035 if (L_IEXTEN(tty
)) {
1036 set_bit(WERASE_CHAR(tty
),
1037 tty
->process_char_map
);
1038 set_bit(LNEXT_CHAR(tty
),
1039 tty
->process_char_map
);
1040 set_bit(EOL2_CHAR(tty
),
1041 tty
->process_char_map
);
1043 set_bit(REPRINT_CHAR(tty
),
1044 tty
->process_char_map
);
1048 set_bit(START_CHAR(tty
), tty
->process_char_map
);
1049 set_bit(STOP_CHAR(tty
), tty
->process_char_map
);
1052 set_bit(INTR_CHAR(tty
), tty
->process_char_map
);
1053 set_bit(QUIT_CHAR(tty
), tty
->process_char_map
);
1054 set_bit(SUSP_CHAR(tty
), tty
->process_char_map
);
1056 clear_bit(__DISABLED_CHAR
, tty
->process_char_map
);
1061 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1062 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1063 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1068 n_tty_set_room(tty
);
1072 * n_tty_close - close the ldisc for this tty
1075 * Called from the terminal layer when this line discipline is
1076 * being shut down, either because of a close or becsuse of a
1077 * discipline change. The function will not be called while other
1078 * ldisc methods are in progress.
1081 static void n_tty_close(struct tty_struct
*tty
)
1083 n_tty_flush_buffer(tty
);
1084 if (tty
->read_buf
) {
1085 free_buf(tty
->read_buf
);
1086 tty
->read_buf
= NULL
;
1091 * n_tty_open - open an ldisc
1092 * @tty: terminal to open
1094 * Called when this line discipline is being attached to the
1095 * terminal device. Can sleep. Called serialized so that no
1096 * other events will occur in parallel. No further open will occur
1100 static int n_tty_open(struct tty_struct
*tty
)
1105 /* This one is ugly. Currently a malloc failure here can panic */
1106 if (!tty
->read_buf
) {
1107 tty
->read_buf
= alloc_buf();
1111 memset(tty
->read_buf
, 0, N_TTY_BUF_SIZE
);
1112 reset_buffer_flags(tty
);
1114 n_tty_set_termios(tty
, NULL
);
1115 tty
->minimum_to_wake
= 1;
1120 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1123 if (tty
->canon_data
)
1125 } else if (tty
->read_cnt
>= (amt
? amt
: 1))
1132 * copy_from_read_buf - copy read data directly
1133 * @tty: terminal device
1137 * Helper function to speed up read_chan. It is only called when
1138 * ICANON is off; it copies characters straight from the tty queue to
1139 * user space directly. It can be profitably called twice; once to
1140 * drain the space from the tail pointer to the (physical) end of the
1141 * buffer, and once to drain the space from the (physical) beginning of
1142 * the buffer to head pointer.
1144 * Called under the tty->atomic_read_lock sem
1148 static int copy_from_read_buf(struct tty_struct
*tty
,
1149 unsigned char __user
**b
,
1155 unsigned long flags
;
1158 spin_lock_irqsave(&tty
->read_lock
, flags
);
1159 n
= min(tty
->read_cnt
, N_TTY_BUF_SIZE
- tty
->read_tail
);
1161 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1163 retval
= copy_to_user(*b
, &tty
->read_buf
[tty
->read_tail
], n
);
1165 tty_audit_add_data(tty
, &tty
->read_buf
[tty
->read_tail
], n
);
1166 spin_lock_irqsave(&tty
->read_lock
, flags
);
1167 tty
->read_tail
= (tty
->read_tail
+ n
) & (N_TTY_BUF_SIZE
-1);
1169 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1176 extern ssize_t
redirected_tty_write(struct file
*,const char *,size_t,loff_t
*);
1179 * job_control - check job control
1181 * @file: file handle
1183 * Perform job control management checks on this file/tty descriptor
1184 * and if appropriate send any needed signals and return a negative
1185 * error code if action should be taken.
1188 static int job_control(struct tty_struct
*tty
, struct file
*file
)
1190 /* Job control check -- must be done at start and after
1191 every sleep (POSIX.1 7.1.1.4). */
1192 /* NOTE: not yet done after every sleep pending a thorough
1193 check of the logic of this change. -- jlc */
1194 /* don't stop on /dev/console */
1195 if (file
->f_op
->write
!= redirected_tty_write
&&
1196 current
->signal
->tty
== tty
) {
1198 printk("read_chan: no tty->pgrp!\n");
1199 else if (task_pgrp(current
) != tty
->pgrp
) {
1200 if (is_ignored(SIGTTIN
) ||
1201 is_current_pgrp_orphaned())
1203 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
1204 set_thread_flag(TIF_SIGPENDING
);
1205 return -ERESTARTSYS
;
1213 * read_chan - read function for tty
1215 * @file: file object
1216 * @buf: userspace buffer pointer
1219 * Perform reads for the line discipline. We are guaranteed that the
1220 * line discipline will not be closed under us but we may get multiple
1221 * parallel readers and must handle this ourselves. We may also get
1222 * a hangup. Always called in user context, may sleep.
1224 * This code must be sure never to sleep through a hangup.
1227 static ssize_t
read_chan(struct tty_struct
*tty
, struct file
*file
,
1228 unsigned char __user
*buf
, size_t nr
)
1230 unsigned char __user
*b
= buf
;
1231 DECLARE_WAITQUEUE(wait
, current
);
1237 unsigned long flags
;
1241 if (!tty
->read_buf
) {
1242 printk("n_tty_read_chan: called with read_buf == NULL?!?\n");
1246 c
= job_control(tty
, file
);
1251 timeout
= MAX_SCHEDULE_TIMEOUT
;
1253 time
= (HZ
/ 10) * TIME_CHAR(tty
);
1254 minimum
= MIN_CHAR(tty
);
1257 tty
->minimum_to_wake
= 1;
1258 else if (!waitqueue_active(&tty
->read_wait
) ||
1259 (tty
->minimum_to_wake
> minimum
))
1260 tty
->minimum_to_wake
= minimum
;
1267 tty
->minimum_to_wake
= minimum
= 1;
1272 * Internal serialization of reads.
1274 if (file
->f_flags
& O_NONBLOCK
) {
1275 if (!mutex_trylock(&tty
->atomic_read_lock
))
1279 if (mutex_lock_interruptible(&tty
->atomic_read_lock
))
1280 return -ERESTARTSYS
;
1283 add_wait_queue(&tty
->read_wait
, &wait
);
1285 /* First test for status change. */
1286 if (tty
->packet
&& tty
->link
->ctrl_status
) {
1290 cs
= tty
->link
->ctrl_status
;
1291 tty
->link
->ctrl_status
= 0;
1292 if (tty_put_user(tty
, cs
, b
++)) {
1300 /* This statement must be first before checking for input
1301 so that any interrupt will set the state back to
1303 set_current_state(TASK_INTERRUPTIBLE
);
1305 if (((minimum
- (b
- buf
)) < tty
->minimum_to_wake
) &&
1306 ((minimum
- (b
- buf
)) >= 1))
1307 tty
->minimum_to_wake
= (minimum
- (b
- buf
));
1309 if (!input_available_p(tty
, 0)) {
1310 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
1314 if (tty_hung_up_p(file
))
1318 if (file
->f_flags
& O_NONBLOCK
) {
1322 if (signal_pending(current
)) {
1323 retval
= -ERESTARTSYS
;
1326 n_tty_set_room(tty
);
1327 timeout
= schedule_timeout(timeout
);
1330 __set_current_state(TASK_RUNNING
);
1332 /* Deal with packet mode. */
1333 if (tty
->packet
&& b
== buf
) {
1334 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
1343 /* N.B. avoid overrun if nr == 0 */
1344 while (nr
&& tty
->read_cnt
) {
1347 eol
= test_and_clear_bit(tty
->read_tail
,
1349 c
= tty
->read_buf
[tty
->read_tail
];
1350 spin_lock_irqsave(&tty
->read_lock
, flags
);
1351 tty
->read_tail
= ((tty
->read_tail
+1) &
1352 (N_TTY_BUF_SIZE
-1));
1355 /* this test should be redundant:
1356 * we shouldn't be reading data if
1359 if (--tty
->canon_data
< 0)
1360 tty
->canon_data
= 0;
1362 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1364 if (!eol
|| (c
!= __DISABLED_CHAR
)) {
1365 if (tty_put_user(tty
, c
, b
++)) {
1373 tty_audit_push(tty
);
1381 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
1382 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
1389 /* If there is enough space in the read buffer now, let the
1390 * low-level driver know. We use n_tty_chars_in_buffer() to
1391 * check the buffer, as it now knows about canonical mode.
1392 * Otherwise, if the driver is throttled and the line is
1393 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1394 * we won't get any more characters.
1396 if (n_tty_chars_in_buffer(tty
) <= TTY_THRESHOLD_UNTHROTTLE
) {
1397 n_tty_set_room(tty
);
1398 check_unthrottle(tty
);
1401 if (b
- buf
>= minimum
)
1406 mutex_unlock(&tty
->atomic_read_lock
);
1407 remove_wait_queue(&tty
->read_wait
, &wait
);
1409 if (!waitqueue_active(&tty
->read_wait
))
1410 tty
->minimum_to_wake
= minimum
;
1412 __set_current_state(TASK_RUNNING
);
1417 clear_bit(TTY_PUSH
, &tty
->flags
);
1418 } else if (test_and_clear_bit(TTY_PUSH
, &tty
->flags
))
1421 n_tty_set_room(tty
);
1427 * write_chan - write function for tty
1429 * @file: file object
1430 * @buf: userspace buffer pointer
1433 * Write function of the terminal device. This is serialized with
1434 * respect to other write callers but not to termios changes, reads
1435 * and other such events. We must be careful with N_TTY as the receive
1436 * code will echo characters, thus calling driver write methods.
1438 * This code must be sure never to sleep through a hangup.
1441 static ssize_t
write_chan(struct tty_struct
* tty
, struct file
* file
,
1442 const unsigned char * buf
, size_t nr
)
1444 const unsigned char *b
= buf
;
1445 DECLARE_WAITQUEUE(wait
, current
);
1449 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1450 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
1451 retval
= tty_check_change(tty
);
1456 add_wait_queue(&tty
->write_wait
, &wait
);
1458 set_current_state(TASK_INTERRUPTIBLE
);
1459 if (signal_pending(current
)) {
1460 retval
= -ERESTARTSYS
;
1463 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
1467 if (O_OPOST(tty
) && !(test_bit(TTY_HW_COOK_OUT
, &tty
->flags
))) {
1469 ssize_t num
= opost_block(tty
, b
, nr
);
1481 if (opost(c
, tty
) < 0)
1485 if (tty
->driver
->flush_chars
)
1486 tty
->driver
->flush_chars(tty
);
1489 c
= tty
->driver
->write(tty
, b
, nr
);
1502 if (file
->f_flags
& O_NONBLOCK
) {
1509 __set_current_state(TASK_RUNNING
);
1510 remove_wait_queue(&tty
->write_wait
, &wait
);
1511 return (b
- buf
) ? b
- buf
: retval
;
1515 * normal_poll - poll method for N_TTY
1516 * @tty: terminal device
1517 * @file: file accessing it
1520 * Called when the line discipline is asked to poll() for data or
1521 * for special events. This code is not serialized with respect to
1522 * other events save open/close.
1524 * This code must be sure never to sleep through a hangup.
1525 * Called without the kernel lock held - fine
1527 * FIXME: if someone changes the VMIN or discipline settings for the
1528 * terminal while another process is in poll() the poll does not
1529 * recompute the new limits. Possibly set_termios should issue
1530 * a read wakeup to fix this bug.
1533 static unsigned int normal_poll(struct tty_struct
* tty
, struct file
* file
, poll_table
*wait
)
1535 unsigned int mask
= 0;
1537 poll_wait(file
, &tty
->read_wait
, wait
);
1538 poll_wait(file
, &tty
->write_wait
, wait
);
1539 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
1540 mask
|= POLLIN
| POLLRDNORM
;
1541 if (tty
->packet
&& tty
->link
->ctrl_status
)
1542 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
1543 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
1545 if (tty_hung_up_p(file
))
1547 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
1548 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
1549 tty
->minimum_to_wake
= MIN_CHAR(tty
);
1551 tty
->minimum_to_wake
= 1;
1553 if (!tty_is_writelocked(tty
) &&
1554 tty
->driver
->chars_in_buffer(tty
) < WAKEUP_CHARS
&&
1555 tty
->driver
->write_room(tty
) > 0)
1556 mask
|= POLLOUT
| POLLWRNORM
;
1560 struct tty_ldisc tty_ldisc_N_TTY
= {
1561 .magic
= TTY_LDISC_MAGIC
,
1564 .close
= n_tty_close
,
1565 .flush_buffer
= n_tty_flush_buffer
,
1566 .chars_in_buffer
= n_tty_chars_in_buffer
,
1568 .write
= write_chan
,
1569 .ioctl
= n_tty_ioctl
,
1570 .set_termios
= n_tty_set_termios
,
1571 .poll
= normal_poll
,
1572 .receive_buf
= n_tty_receive_buf
,
1573 .write_wakeup
= n_tty_write_wakeup