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).
189 static void n_tty_flush_buffer(struct tty_struct
*tty
)
192 /* clear everything and unthrottle the driver */
193 reset_buffer_flags(tty
);
198 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
199 if (tty
->link
->packet
) {
200 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
201 wake_up_interruptible(&tty
->link
->read_wait
);
203 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
207 * n_tty_chars_in_buffer - report available bytes
210 * Report the number of characters buffered to be delivered to user
211 * at this instant in time.
214 static ssize_t
n_tty_chars_in_buffer(struct tty_struct
*tty
)
219 spin_lock_irqsave(&tty
->read_lock
, flags
);
222 } else if (tty
->canon_data
) {
223 n
= (tty
->canon_head
> tty
->read_tail
) ?
224 tty
->canon_head
- tty
->read_tail
:
225 tty
->canon_head
+ (N_TTY_BUF_SIZE
- tty
->read_tail
);
227 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
232 * is_utf8_continuation - utf8 multibyte check
235 * Returns true if the utf8 character 'c' is a multibyte continuation
236 * character. We use this to correctly compute the on screen size
237 * of the character when printing
240 static inline int is_utf8_continuation(unsigned char c
)
242 return (c
& 0xc0) == 0x80;
246 * is_continuation - multibyte check
249 * Returns true if the utf8 character 'c' is a multibyte continuation
250 * character and the terminal is in unicode mode.
253 static inline int is_continuation(unsigned char c
, struct tty_struct
*tty
)
255 return I_IUTF8(tty
) && is_utf8_continuation(c
);
259 * opost - output post processor
260 * @c: character (or partial unicode symbol)
261 * @tty: terminal device
263 * Perform OPOST processing. Returns -1 when the output device is
264 * full and the character must be retried. Note that Linux currently
265 * ignores TABDLY, CRDLY, VTDLY, FFDLY and NLDLY. They simply aren't
266 * relevant in the world today. If you ever need them, add them here.
268 * Called from both the receive and transmit sides and can be called
269 * re-entrantly. Relies on lock_kernel() for tty->column state.
272 static int opost(unsigned char c
, struct tty_struct
*tty
)
276 space
= tty
->driver
->write_room(tty
);
289 tty
->driver
->put_char(tty
, '\r');
292 tty
->canon_column
= tty
->column
;
295 if (O_ONOCR(tty
) && tty
->column
== 0)
300 tty
->canon_column
= tty
->column
= 0;
303 tty
->canon_column
= tty
->column
= 0;
306 spaces
= 8 - (tty
->column
& 7);
307 if (O_TABDLY(tty
) == XTABS
) {
310 tty
->column
+= spaces
;
311 tty
->driver
->write(tty
, " ", spaces
);
314 tty
->column
+= spaces
;
323 if (!iscntrl(c
) && !is_continuation(c
, tty
))
328 tty
->driver
->put_char(tty
, c
);
334 * opost_block - block postprocess
335 * @tty: terminal device
336 * @inbuf: user buffer
337 * @nr: number of bytes
339 * This path is used to speed up block console writes, among other
340 * things when processing blocks of output data. It handles only
341 * the simple cases normally found and helps to generate blocks of
342 * symbols for the console driver and thus improve performance.
344 * Called from write_chan under the tty layer write lock. Relies
345 * on lock_kernel for the tty->column state.
348 static ssize_t
opost_block(struct tty_struct
*tty
,
349 const unsigned char *buf
, unsigned int nr
)
353 const unsigned char *cp
;
355 space
= tty
->driver
->write_room(tty
);
362 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
369 tty
->canon_column
= tty
->column
;
372 if (O_ONOCR(tty
) && tty
->column
== 0)
376 tty
->canon_column
= tty
->column
= 0;
393 if (tty
->driver
->flush_chars
)
394 tty
->driver
->flush_chars(tty
);
395 i
= tty
->driver
->write(tty
, buf
, i
);
402 * put_char - write character to driver
403 * @c: character (or part of unicode symbol)
404 * @tty: terminal device
406 * Queue a byte to the driver layer for output
409 static inline void put_char(unsigned char c
, struct tty_struct
*tty
)
411 tty
->driver
->put_char(tty
, c
);
415 * echo_char - echo characters
416 * @c: unicode byte to echo
417 * @tty: terminal device
419 * Echo user input back onto the screen. This must be called only when
420 * L_ECHO(tty) is true. Called from the driver receive_buf path.
423 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
425 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t') {
427 put_char(c
^ 0100, tty
);
433 static inline void finish_erasing(struct tty_struct
*tty
)
443 * eraser - handle erase function
444 * @c: character input
445 * @tty: terminal device
447 * Perform erase and necessary output when an erase character is
448 * present in the stream from the driver layer. Handles the complexities
449 * of UTF-8 multibyte symbols.
452 static void eraser(unsigned char c
, struct tty_struct
*tty
)
454 enum { ERASE
, WERASE
, KILL
} kill_type
;
455 int head
, seen_alnums
, cnt
;
458 if (tty
->read_head
== tty
->canon_head
) {
459 /* opost('\a', tty); */ /* what do you think? */
462 if (c
== ERASE_CHAR(tty
))
464 else if (c
== WERASE_CHAR(tty
))
468 spin_lock_irqsave(&tty
->read_lock
, flags
);
469 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
470 (N_TTY_BUF_SIZE
- 1));
471 tty
->read_head
= tty
->canon_head
;
472 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
475 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(tty
)) {
476 spin_lock_irqsave(&tty
->read_lock
, flags
);
477 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
478 (N_TTY_BUF_SIZE
- 1));
479 tty
->read_head
= tty
->canon_head
;
480 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
482 echo_char(KILL_CHAR(tty
), tty
);
483 /* Add a newline if ECHOK is on and ECHOKE is off. */
492 while (tty
->read_head
!= tty
->canon_head
) {
493 head
= tty
->read_head
;
495 /* erase a single possibly multibyte character */
497 head
= (head
- 1) & (N_TTY_BUF_SIZE
-1);
498 c
= tty
->read_buf
[head
];
499 } while (is_continuation(c
, tty
) && head
!= tty
->canon_head
);
501 /* do not partially erase */
502 if (is_continuation(c
, tty
))
505 if (kill_type
== WERASE
) {
506 /* Equivalent to BSD's ALTWERASE. */
507 if (isalnum(c
) || c
== '_')
509 else if (seen_alnums
)
512 cnt
= (tty
->read_head
- head
) & (N_TTY_BUF_SIZE
-1);
513 spin_lock_irqsave(&tty
->read_lock
, flags
);
514 tty
->read_head
= head
;
515 tty
->read_cnt
-= cnt
;
516 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
518 if (L_ECHOPRT(tty
)) {
524 /* if cnt > 1, output a multi-byte character */
527 head
= (head
+1) & (N_TTY_BUF_SIZE
-1);
528 put_char(tty
->read_buf
[head
], tty
);
530 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
531 echo_char(ERASE_CHAR(tty
), tty
);
532 } else if (c
== '\t') {
533 unsigned int col
= tty
->canon_column
;
534 unsigned long tail
= tty
->canon_head
;
536 /* Find the column of the last char. */
537 while (tail
!= tty
->read_head
) {
538 c
= tty
->read_buf
[tail
];
541 else if (iscntrl(c
)) {
544 } else if (!is_continuation(c
, tty
))
546 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
549 /* should never happen */
550 if (tty
->column
> 0x80000000)
553 /* Now backup to that column. */
554 while (tty
->column
> col
) {
555 /* Can't use opost here. */
561 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
568 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
577 if (kill_type
== ERASE
)
580 if (tty
->read_head
== tty
->canon_head
)
585 * isig - handle the ISIG optio
588 * @flush: force flush
590 * Called when a signal is being sent due to terminal input. This
591 * may caus terminal flushing to take place according to the termios
592 * settings and character used. Called from the driver receive_buf
593 * path so serialized.
596 static inline void isig(int sig
, struct tty_struct
*tty
, int flush
)
599 kill_pgrp(tty
->pgrp
, sig
, 1);
600 if (flush
|| !L_NOFLSH(tty
)) {
601 n_tty_flush_buffer(tty
);
602 if (tty
->driver
->flush_buffer
)
603 tty
->driver
->flush_buffer(tty
);
608 * n_tty_receive_break - handle break
611 * An RS232 break event has been hit in the incoming bitstream. This
612 * can cause a variety of events depending upon the termios settings.
614 * Called from the receive_buf path so single threaded.
617 static inline void n_tty_receive_break(struct tty_struct
*tty
)
622 isig(SIGINT
, tty
, 1);
626 put_tty_queue('\377', tty
);
627 put_tty_queue('\0', tty
);
629 put_tty_queue('\0', tty
);
630 wake_up_interruptible(&tty
->read_wait
);
634 * n_tty_receive_overrun - handle overrun reporting
637 * Data arrived faster than we could process it. While the tty
638 * driver has flagged this the bits that were missed are gone
641 * Called from the receive_buf path so single threaded. Does not
642 * need locking as num_overrun and overrun_time are function
646 static inline void n_tty_receive_overrun(struct tty_struct
*tty
)
651 if (time_before(tty
->overrun_time
, jiffies
- HZ
) ||
652 time_after(tty
->overrun_time
, jiffies
)) {
653 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
656 tty
->overrun_time
= jiffies
;
657 tty
->num_overrun
= 0;
662 * n_tty_receive_parity_error - error notifier
663 * @tty: terminal device
666 * Process a parity error and queue the right data to indicate
667 * the error case if necessary. Locking as per n_tty_receive_buf.
669 static inline void n_tty_receive_parity_error(struct tty_struct
*tty
,
675 put_tty_queue('\377', tty
);
676 put_tty_queue('\0', tty
);
677 put_tty_queue(c
, tty
);
678 } else if (I_INPCK(tty
))
679 put_tty_queue('\0', tty
);
681 put_tty_queue(c
, tty
);
682 wake_up_interruptible(&tty
->read_wait
);
686 * n_tty_receive_char - perform processing
687 * @tty: terminal device
690 * Process an individual character of input received from the driver.
691 * This is serialized with respect to itself by the rules for the
695 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
700 put_tty_queue(c
, tty
);
706 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
709 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) &&
710 ((I_IXANY(tty
) && c
!= START_CHAR(tty
) && c
!= STOP_CHAR(tty
)) ||
711 c
== INTR_CHAR(tty
) || c
== QUIT_CHAR(tty
) || c
== SUSP_CHAR(tty
)))
716 if (c
== START_CHAR(tty
))
718 else if (c
== STOP_CHAR(tty
))
725 * If the previous character was LNEXT, or we know that this
726 * character is not one of the characters that we'll have to
727 * handle specially, do shortcut processing to speed things
730 if (!test_bit(c
, tty
->process_char_map
) || tty
->lnext
) {
734 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1) {
735 put_char('\a', tty
); /* beep if no space */
738 /* Record the column of first canon char. */
739 if (tty
->canon_head
== tty
->read_head
)
740 tty
->canon_column
= tty
->column
;
743 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
744 put_tty_queue(c
, tty
);
745 put_tty_queue(c
, tty
);
750 if (c
== START_CHAR(tty
)) {
754 if (c
== STOP_CHAR(tty
)) {
763 if (c
== INTR_CHAR(tty
))
766 if (c
== QUIT_CHAR(tty
))
769 if (c
== SUSP_CHAR(tty
)) {
772 * Echo character, and then send the signal.
773 * Note that we do not use isig() here because we want
775 * 1) flush, 2) echo, 3) signal
777 if (!L_NOFLSH(tty
)) {
778 n_tty_flush_buffer(tty
);
779 if (tty
->driver
->flush_buffer
)
780 tty
->driver
->flush_buffer(tty
);
785 kill_pgrp(tty
->pgrp
, signal
, 1);
795 } else if (c
== '\n' && I_INLCR(tty
))
799 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
800 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
804 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
808 if (L_ECHOCTL(tty
)) {
815 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
817 unsigned long tail
= tty
->canon_head
;
822 while (tail
!= tty
->read_head
) {
823 echo_char(tty
->read_buf
[tail
], tty
);
824 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
829 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
830 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1)
836 if (c
== EOF_CHAR(tty
)) {
837 if (tty
->canon_head
!= tty
->read_head
)
838 set_bit(TTY_PUSH
, &tty
->flags
);
842 if ((c
== EOL_CHAR(tty
)) ||
843 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
845 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
848 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1)
850 /* Record the column of first canon char. */
851 if (tty
->canon_head
== tty
->read_head
)
852 tty
->canon_column
= tty
->column
;
856 * XXX does PARMRK doubling happen for
857 * EOL_CHAR and EOL2_CHAR?
859 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
860 put_tty_queue(c
, tty
);
863 spin_lock_irqsave(&tty
->read_lock
, flags
);
864 set_bit(tty
->read_head
, tty
->read_flags
);
865 put_tty_queue_nolock(c
, tty
);
866 tty
->canon_head
= tty
->read_head
;
868 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
869 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
870 if (waitqueue_active(&tty
->read_wait
))
871 wake_up_interruptible(&tty
->read_wait
);
878 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1) {
879 put_char('\a', tty
); /* beep if no space */
885 /* Record the column of first canon char. */
886 if (tty
->canon_head
== tty
->read_head
)
887 tty
->canon_column
= tty
->column
;
892 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
893 put_tty_queue(c
, tty
);
895 put_tty_queue(c
, tty
);
900 * n_tty_write_wakeup - asynchronous I/O notifier
903 * Required for the ptys, serial driver etc. since processes
904 * that attach themselves to the master and rely on ASYNC
905 * IO must be woken up
908 static void n_tty_write_wakeup(struct tty_struct
*tty
)
911 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
912 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
917 * n_tty_receive_buf - data receive
918 * @tty: terminal device
923 * Called by the terminal driver when a block of characters has
924 * been received. This function must be called from soft contexts
925 * not from interrupt context. The driver is responsible for making
926 * calls one at a time and in order (or using flush_to_ldisc)
929 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
932 const unsigned char *p
;
933 char *f
, flags
= TTY_NORMAL
;
936 unsigned long cpuflags
;
942 spin_lock_irqsave(&tty
->read_lock
, cpuflags
);
943 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
944 N_TTY_BUF_SIZE
- tty
->read_head
);
946 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
947 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
952 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
953 N_TTY_BUF_SIZE
- tty
->read_head
);
955 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
956 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
958 spin_unlock_irqrestore(&tty
->read_lock
, cpuflags
);
960 for (i
= count
, p
= cp
, f
= fp
; i
; i
--, p
++) {
965 n_tty_receive_char(tty
, *p
);
968 n_tty_receive_break(tty
);
972 n_tty_receive_parity_error(tty
, *p
);
975 n_tty_receive_overrun(tty
);
978 printk(KERN_ERR
"%s: unknown flag %d\n",
979 tty_name(tty
, buf
), flags
);
983 if (tty
->driver
->flush_chars
)
984 tty
->driver
->flush_chars(tty
);
989 if (!tty
->icanon
&& (tty
->read_cnt
>= tty
->minimum_to_wake
)) {
990 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
991 if (waitqueue_active(&tty
->read_wait
))
992 wake_up_interruptible(&tty
->read_wait
);
996 * Check the remaining room for the input canonicalization
997 * mode. We don't want to throttle the driver if we're in
998 * canonical mode and don't have a newline yet!
1000 if (tty
->receive_room
< TTY_THRESHOLD_THROTTLE
) {
1001 /* check TTY_THROTTLED first so it indicates our state */
1002 if (!test_and_set_bit(TTY_THROTTLED
, &tty
->flags
) &&
1003 tty
->driver
->throttle
)
1004 tty
->driver
->throttle(tty
);
1008 int is_ignored(int sig
)
1010 return (sigismember(¤t
->blocked
, sig
) ||
1011 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
1015 * n_tty_set_termios - termios data changed
1017 * @old: previous data
1019 * Called by the tty layer when the user changes termios flags so
1020 * that the line discipline can plan ahead. This function cannot sleep
1021 * and is protected from re-entry by the tty layer. The user is
1022 * guaranteed that this function will not be re-entered or in progress
1023 * when the ldisc is closed.
1026 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1031 tty
->icanon
= (L_ICANON(tty
) != 0);
1032 if (test_bit(TTY_HW_COOK_IN
, &tty
->flags
)) {
1035 n_tty_set_room(tty
);
1038 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1039 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1040 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1042 memset(tty
->process_char_map
, 0, 256/8);
1044 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1045 set_bit('\r', tty
->process_char_map
);
1047 set_bit('\n', tty
->process_char_map
);
1049 if (L_ICANON(tty
)) {
1050 set_bit(ERASE_CHAR(tty
), tty
->process_char_map
);
1051 set_bit(KILL_CHAR(tty
), tty
->process_char_map
);
1052 set_bit(EOF_CHAR(tty
), tty
->process_char_map
);
1053 set_bit('\n', tty
->process_char_map
);
1054 set_bit(EOL_CHAR(tty
), tty
->process_char_map
);
1055 if (L_IEXTEN(tty
)) {
1056 set_bit(WERASE_CHAR(tty
),
1057 tty
->process_char_map
);
1058 set_bit(LNEXT_CHAR(tty
),
1059 tty
->process_char_map
);
1060 set_bit(EOL2_CHAR(tty
),
1061 tty
->process_char_map
);
1063 set_bit(REPRINT_CHAR(tty
),
1064 tty
->process_char_map
);
1068 set_bit(START_CHAR(tty
), tty
->process_char_map
);
1069 set_bit(STOP_CHAR(tty
), tty
->process_char_map
);
1072 set_bit(INTR_CHAR(tty
), tty
->process_char_map
);
1073 set_bit(QUIT_CHAR(tty
), tty
->process_char_map
);
1074 set_bit(SUSP_CHAR(tty
), tty
->process_char_map
);
1076 clear_bit(__DISABLED_CHAR
, tty
->process_char_map
);
1081 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1082 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1083 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1088 n_tty_set_room(tty
);
1092 * n_tty_close - close the ldisc for this tty
1095 * Called from the terminal layer when this line discipline is
1096 * being shut down, either because of a close or becsuse of a
1097 * discipline change. The function will not be called while other
1098 * ldisc methods are in progress.
1101 static void n_tty_close(struct tty_struct
*tty
)
1103 n_tty_flush_buffer(tty
);
1104 if (tty
->read_buf
) {
1105 free_buf(tty
->read_buf
);
1106 tty
->read_buf
= NULL
;
1111 * n_tty_open - open an ldisc
1112 * @tty: terminal to open
1114 * Called when this line discipline is being attached to the
1115 * terminal device. Can sleep. Called serialized so that no
1116 * other events will occur in parallel. No further open will occur
1120 static int n_tty_open(struct tty_struct
*tty
)
1125 /* This one is ugly. Currently a malloc failure here can panic */
1126 if (!tty
->read_buf
) {
1127 tty
->read_buf
= alloc_buf();
1131 memset(tty
->read_buf
, 0, N_TTY_BUF_SIZE
);
1132 reset_buffer_flags(tty
);
1134 n_tty_set_termios(tty
, NULL
);
1135 tty
->minimum_to_wake
= 1;
1140 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1143 if (tty
->canon_data
)
1145 } else if (tty
->read_cnt
>= (amt
? amt
: 1))
1152 * copy_from_read_buf - copy read data directly
1153 * @tty: terminal device
1157 * Helper function to speed up read_chan. It is only called when
1158 * ICANON is off; it copies characters straight from the tty queue to
1159 * user space directly. It can be profitably called twice; once to
1160 * drain the space from the tail pointer to the (physical) end of the
1161 * buffer, and once to drain the space from the (physical) beginning of
1162 * the buffer to head pointer.
1164 * Called under the tty->atomic_read_lock sem
1168 static int copy_from_read_buf(struct tty_struct
*tty
,
1169 unsigned char __user
**b
,
1175 unsigned long flags
;
1178 spin_lock_irqsave(&tty
->read_lock
, flags
);
1179 n
= min(tty
->read_cnt
, N_TTY_BUF_SIZE
- tty
->read_tail
);
1181 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1183 retval
= copy_to_user(*b
, &tty
->read_buf
[tty
->read_tail
], n
);
1185 tty_audit_add_data(tty
, &tty
->read_buf
[tty
->read_tail
], n
);
1186 spin_lock_irqsave(&tty
->read_lock
, flags
);
1187 tty
->read_tail
= (tty
->read_tail
+ n
) & (N_TTY_BUF_SIZE
-1);
1189 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1196 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
1200 * job_control - check job control
1202 * @file: file handle
1204 * Perform job control management checks on this file/tty descriptor
1205 * and if appropriate send any needed signals and return a negative
1206 * error code if action should be taken.
1209 * Locking: None - redirected write test is safe, testing
1210 * current->signal should possibly lock current->sighand
1214 static int job_control(struct tty_struct
*tty
, struct file
*file
)
1216 /* Job control check -- must be done at start and after
1217 every sleep (POSIX.1 7.1.1.4). */
1218 /* NOTE: not yet done after every sleep pending a thorough
1219 check of the logic of this change. -- jlc */
1220 /* don't stop on /dev/console */
1221 if (file
->f_op
->write
!= redirected_tty_write
&&
1222 current
->signal
->tty
== tty
) {
1224 printk(KERN_ERR
"read_chan: no tty->pgrp!\n");
1225 else if (task_pgrp(current
) != tty
->pgrp
) {
1226 if (is_ignored(SIGTTIN
) ||
1227 is_current_pgrp_orphaned())
1229 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
1230 set_thread_flag(TIF_SIGPENDING
);
1231 return -ERESTARTSYS
;
1239 * read_chan - read function for tty
1241 * @file: file object
1242 * @buf: userspace buffer pointer
1245 * Perform reads for the line discipline. We are guaranteed that the
1246 * line discipline will not be closed under us but we may get multiple
1247 * parallel readers and must handle this ourselves. We may also get
1248 * a hangup. Always called in user context, may sleep.
1250 * This code must be sure never to sleep through a hangup.
1253 static ssize_t
read_chan(struct tty_struct
*tty
, struct file
*file
,
1254 unsigned char __user
*buf
, size_t nr
)
1256 unsigned char __user
*b
= buf
;
1257 DECLARE_WAITQUEUE(wait
, current
);
1263 unsigned long flags
;
1268 if (!tty
->read_buf
) {
1269 printk(KERN_ERR
"n_tty_read_chan: read_buf == NULL?!?\n");
1273 c
= job_control(tty
, file
);
1278 timeout
= MAX_SCHEDULE_TIMEOUT
;
1280 time
= (HZ
/ 10) * TIME_CHAR(tty
);
1281 minimum
= MIN_CHAR(tty
);
1284 tty
->minimum_to_wake
= 1;
1285 else if (!waitqueue_active(&tty
->read_wait
) ||
1286 (tty
->minimum_to_wake
> minimum
))
1287 tty
->minimum_to_wake
= minimum
;
1294 tty
->minimum_to_wake
= minimum
= 1;
1299 * Internal serialization of reads.
1301 if (file
->f_flags
& O_NONBLOCK
) {
1302 if (!mutex_trylock(&tty
->atomic_read_lock
))
1305 if (mutex_lock_interruptible(&tty
->atomic_read_lock
))
1306 return -ERESTARTSYS
;
1308 packet
= tty
->packet
;
1310 add_wait_queue(&tty
->read_wait
, &wait
);
1312 /* First test for status change. */
1313 if (packet
&& tty
->link
->ctrl_status
) {
1317 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
1318 cs
= tty
->link
->ctrl_status
;
1319 tty
->link
->ctrl_status
= 0;
1320 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
1321 if (tty_put_user(tty
, cs
, b
++)) {
1329 /* This statement must be first before checking for input
1330 so that any interrupt will set the state back to
1332 set_current_state(TASK_INTERRUPTIBLE
);
1334 if (((minimum
- (b
- buf
)) < tty
->minimum_to_wake
) &&
1335 ((minimum
- (b
- buf
)) >= 1))
1336 tty
->minimum_to_wake
= (minimum
- (b
- buf
));
1338 if (!input_available_p(tty
, 0)) {
1339 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
1343 if (tty_hung_up_p(file
))
1347 if (file
->f_flags
& O_NONBLOCK
) {
1351 if (signal_pending(current
)) {
1352 retval
= -ERESTARTSYS
;
1355 /* FIXME: does n_tty_set_room need locking ? */
1356 n_tty_set_room(tty
);
1357 timeout
= schedule_timeout(timeout
);
1360 __set_current_state(TASK_RUNNING
);
1362 /* Deal with packet mode. */
1363 if (packet
&& b
== buf
) {
1364 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
1373 /* N.B. avoid overrun if nr == 0 */
1374 while (nr
&& tty
->read_cnt
) {
1377 eol
= test_and_clear_bit(tty
->read_tail
,
1379 c
= tty
->read_buf
[tty
->read_tail
];
1380 spin_lock_irqsave(&tty
->read_lock
, flags
);
1381 tty
->read_tail
= ((tty
->read_tail
+1) &
1382 (N_TTY_BUF_SIZE
-1));
1385 /* this test should be redundant:
1386 * we shouldn't be reading data if
1389 if (--tty
->canon_data
< 0)
1390 tty
->canon_data
= 0;
1392 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1394 if (!eol
|| (c
!= __DISABLED_CHAR
)) {
1395 if (tty_put_user(tty
, c
, b
++)) {
1403 tty_audit_push(tty
);
1411 /* The copy function takes the read lock and handles
1412 locking internally for this case */
1413 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
1414 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
1421 /* If there is enough space in the read buffer now, let the
1422 * low-level driver know. We use n_tty_chars_in_buffer() to
1423 * check the buffer, as it now knows about canonical mode.
1424 * Otherwise, if the driver is throttled and the line is
1425 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1426 * we won't get any more characters.
1428 if (n_tty_chars_in_buffer(tty
) <= TTY_THRESHOLD_UNTHROTTLE
) {
1429 n_tty_set_room(tty
);
1430 check_unthrottle(tty
);
1433 if (b
- buf
>= minimum
)
1438 mutex_unlock(&tty
->atomic_read_lock
);
1439 remove_wait_queue(&tty
->read_wait
, &wait
);
1441 if (!waitqueue_active(&tty
->read_wait
))
1442 tty
->minimum_to_wake
= minimum
;
1444 __set_current_state(TASK_RUNNING
);
1449 clear_bit(TTY_PUSH
, &tty
->flags
);
1450 } else if (test_and_clear_bit(TTY_PUSH
, &tty
->flags
))
1453 n_tty_set_room(tty
);
1458 * write_chan - write function for tty
1460 * @file: file object
1461 * @buf: userspace buffer pointer
1464 * Write function of the terminal device. This is serialized with
1465 * respect to other write callers but not to termios changes, reads
1466 * and other such events. We must be careful with N_TTY as the receive
1467 * code will echo characters, thus calling driver write methods.
1469 * This code must be sure never to sleep through a hangup.
1472 static ssize_t
write_chan(struct tty_struct
*tty
, struct file
*file
,
1473 const unsigned char *buf
, size_t nr
)
1475 const unsigned char *b
= buf
;
1476 DECLARE_WAITQUEUE(wait
, current
);
1480 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1481 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
1482 retval
= tty_check_change(tty
);
1487 add_wait_queue(&tty
->write_wait
, &wait
);
1489 set_current_state(TASK_INTERRUPTIBLE
);
1490 if (signal_pending(current
)) {
1491 retval
= -ERESTARTSYS
;
1494 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
1498 if (O_OPOST(tty
) && !(test_bit(TTY_HW_COOK_OUT
, &tty
->flags
))) {
1500 ssize_t num
= opost_block(tty
, b
, nr
);
1512 if (opost(c
, tty
) < 0)
1516 if (tty
->driver
->flush_chars
)
1517 tty
->driver
->flush_chars(tty
);
1520 c
= tty
->driver
->write(tty
, b
, nr
);
1533 if (file
->f_flags
& O_NONBLOCK
) {
1540 __set_current_state(TASK_RUNNING
);
1541 remove_wait_queue(&tty
->write_wait
, &wait
);
1542 return (b
- buf
) ? b
- buf
: retval
;
1546 * normal_poll - poll method for N_TTY
1547 * @tty: terminal device
1548 * @file: file accessing it
1551 * Called when the line discipline is asked to poll() for data or
1552 * for special events. This code is not serialized with respect to
1553 * other events save open/close.
1555 * This code must be sure never to sleep through a hangup.
1556 * Called without the kernel lock held - fine
1558 * FIXME: if someone changes the VMIN or discipline settings for the
1559 * terminal while another process is in poll() the poll does not
1560 * recompute the new limits. Possibly set_termios should issue
1561 * a read wakeup to fix this bug.
1564 static unsigned int normal_poll(struct tty_struct
*tty
, struct file
*file
,
1567 unsigned int mask
= 0;
1569 poll_wait(file
, &tty
->read_wait
, wait
);
1570 poll_wait(file
, &tty
->write_wait
, wait
);
1571 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
1572 mask
|= POLLIN
| POLLRDNORM
;
1573 if (tty
->packet
&& tty
->link
->ctrl_status
)
1574 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
1575 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
1577 if (tty_hung_up_p(file
))
1579 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
1580 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
1581 tty
->minimum_to_wake
= MIN_CHAR(tty
);
1583 tty
->minimum_to_wake
= 1;
1585 if (!tty_is_writelocked(tty
) &&
1586 tty
->driver
->chars_in_buffer(tty
) < WAKEUP_CHARS
&&
1587 tty
->driver
->write_room(tty
) > 0)
1588 mask
|= POLLOUT
| POLLWRNORM
;
1592 struct tty_ldisc tty_ldisc_N_TTY
= {
1593 .magic
= TTY_LDISC_MAGIC
,
1596 .close
= n_tty_close
,
1597 .flush_buffer
= n_tty_flush_buffer
,
1598 .chars_in_buffer
= n_tty_chars_in_buffer
,
1600 .write
= write_chan
,
1601 .ioctl
= n_tty_ioctl
,
1602 .set_termios
= n_tty_set_termios
,
1603 .poll
= normal_poll
,
1604 .receive_buf
= n_tty_receive_buf
,
1605 .write_wakeup
= n_tty_write_wakeup