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
)
155 * reset_buffer_flags - reset buffer state
156 * @tty: terminal to reset
158 * Reset the read buffer counters, clear the flags,
159 * and make sure the driver is unthrottled. Called
160 * from n_tty_open() and n_tty_flush_buffer().
162 static void reset_buffer_flags(struct tty_struct
*tty
)
166 spin_lock_irqsave(&tty
->read_lock
, flags
);
167 tty
->read_head
= tty
->read_tail
= tty
->read_cnt
= 0;
168 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
169 tty
->canon_head
= tty
->canon_data
= tty
->erasing
= 0;
170 memset(&tty
->read_flags
, 0, sizeof tty
->read_flags
);
172 check_unthrottle(tty
);
176 * n_tty_flush_buffer - clean input queue
177 * @tty: terminal device
179 * Flush the input buffer. Called when the line discipline is
180 * being closed, when the tty layer wants the buffer flushed (eg
181 * at hangup) or when the N_TTY line discipline internally has to
182 * clean the pending queue (for example some signals).
187 static void n_tty_flush_buffer(struct tty_struct
*tty
)
190 /* clear everything and unthrottle the driver */
191 reset_buffer_flags(tty
);
196 spin_lock_irqsave(&tty
->ctrl_lock
, flags
);
197 if (tty
->link
->packet
) {
198 tty
->ctrl_status
|= TIOCPKT_FLUSHREAD
;
199 wake_up_interruptible(&tty
->link
->read_wait
);
201 spin_unlock_irqrestore(&tty
->ctrl_lock
, flags
);
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() for tty->column state.
270 static int opost(unsigned char c
, struct tty_struct
*tty
)
274 space
= tty_write_room(tty
);
287 tty_put_char(tty
, '\r');
290 tty
->canon_column
= tty
->column
;
293 if (O_ONOCR(tty
) && tty
->column
== 0)
298 tty
->canon_column
= tty
->column
= 0;
301 tty
->canon_column
= tty
->column
= 0;
304 spaces
= 8 - (tty
->column
& 7);
305 if (O_TABDLY(tty
) == XTABS
) {
308 tty
->column
+= spaces
;
309 tty
->ops
->write(tty
, " ", spaces
);
312 tty
->column
+= spaces
;
321 if (!iscntrl(c
) && !is_continuation(c
, tty
))
326 tty_put_char(tty
, c
);
332 * opost_block - block postprocess
333 * @tty: terminal device
334 * @inbuf: user buffer
335 * @nr: number of bytes
337 * This path is used to speed up block console writes, among other
338 * things when processing blocks of output data. It handles only
339 * the simple cases normally found and helps to generate blocks of
340 * symbols for the console driver and thus improve performance.
342 * Called from write_chan under the tty layer write lock. Relies
343 * on lock_kernel for the tty->column state.
346 static ssize_t
opost_block(struct tty_struct
*tty
,
347 const unsigned char *buf
, unsigned int nr
)
351 const unsigned char *cp
;
353 space
= tty_write_room(tty
);
360 for (i
= 0, cp
= buf
; i
< nr
; i
++, cp
++) {
367 tty
->canon_column
= tty
->column
;
370 if (O_ONOCR(tty
) && tty
->column
== 0)
374 tty
->canon_column
= tty
->column
= 0;
391 if (tty
->ops
->flush_chars
)
392 tty
->ops
->flush_chars(tty
);
393 i
= tty
->ops
->write(tty
, buf
, i
);
400 * echo_char - echo characters
401 * @c: unicode byte to echo
402 * @tty: terminal device
404 * Echo user input back onto the screen. This must be called only when
405 * L_ECHO(tty) is true. Called from the driver receive_buf path.
408 static void echo_char(unsigned char c
, struct tty_struct
*tty
)
410 if (L_ECHOCTL(tty
) && iscntrl(c
) && c
!= '\t') {
411 tty_put_char(tty
, '^');
412 tty_put_char(tty
, c
^ 0100);
418 static inline void finish_erasing(struct tty_struct
*tty
)
421 tty_put_char(tty
, '/');
428 * eraser - handle erase function
429 * @c: character input
430 * @tty: terminal device
432 * Perform erase and necessary output when an erase character is
433 * present in the stream from the driver layer. Handles the complexities
434 * of UTF-8 multibyte symbols.
437 static void eraser(unsigned char c
, struct tty_struct
*tty
)
439 enum { ERASE
, WERASE
, KILL
} kill_type
;
440 int head
, seen_alnums
, cnt
;
443 if (tty
->read_head
== tty
->canon_head
) {
444 /* opost('\a', tty); */ /* what do you think? */
447 if (c
== ERASE_CHAR(tty
))
449 else if (c
== WERASE_CHAR(tty
))
453 spin_lock_irqsave(&tty
->read_lock
, flags
);
454 tty
->read_cnt
-= ((tty
->read_head
- tty
->canon_head
) &
455 (N_TTY_BUF_SIZE
- 1));
456 tty
->read_head
= tty
->canon_head
;
457 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
460 if (!L_ECHOK(tty
) || !L_ECHOKE(tty
) || !L_ECHOE(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
);
467 echo_char(KILL_CHAR(tty
), tty
);
468 /* Add a newline if ECHOK is on and ECHOKE is off. */
477 while (tty
->read_head
!= tty
->canon_head
) {
478 head
= tty
->read_head
;
480 /* erase a single possibly multibyte character */
482 head
= (head
- 1) & (N_TTY_BUF_SIZE
-1);
483 c
= tty
->read_buf
[head
];
484 } while (is_continuation(c
, tty
) && head
!= tty
->canon_head
);
486 /* do not partially erase */
487 if (is_continuation(c
, tty
))
490 if (kill_type
== WERASE
) {
491 /* Equivalent to BSD's ALTWERASE. */
492 if (isalnum(c
) || c
== '_')
494 else if (seen_alnums
)
497 cnt
= (tty
->read_head
- head
) & (N_TTY_BUF_SIZE
-1);
498 spin_lock_irqsave(&tty
->read_lock
, flags
);
499 tty
->read_head
= head
;
500 tty
->read_cnt
-= cnt
;
501 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
503 if (L_ECHOPRT(tty
)) {
505 tty_put_char(tty
, '\\');
509 /* if cnt > 1, output a multi-byte character */
512 head
= (head
+1) & (N_TTY_BUF_SIZE
-1);
513 tty_put_char(tty
, tty
->read_buf
[head
]);
515 } else if (kill_type
== ERASE
&& !L_ECHOE(tty
)) {
516 echo_char(ERASE_CHAR(tty
), tty
);
517 } else if (c
== '\t') {
518 unsigned int col
= tty
->canon_column
;
519 unsigned long tail
= tty
->canon_head
;
521 /* Find the column of the last char. */
522 while (tail
!= tty
->read_head
) {
523 c
= tty
->read_buf
[tail
];
526 else if (iscntrl(c
)) {
529 } else if (!is_continuation(c
, tty
))
531 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
534 /* should never happen */
535 if (tty
->column
> 0x80000000)
538 /* Now backup to that column. */
539 while (tty
->column
> col
) {
540 /* Can't use opost here. */
541 tty_put_char(tty
, '\b');
546 if (iscntrl(c
) && L_ECHOCTL(tty
)) {
547 tty_put_char(tty
, '\b');
548 tty_put_char(tty
, ' ');
549 tty_put_char(tty
, '\b');
553 if (!iscntrl(c
) || L_ECHOCTL(tty
)) {
554 tty_put_char(tty
, '\b');
555 tty_put_char(tty
, ' ');
556 tty_put_char(tty
, '\b');
562 if (kill_type
== ERASE
)
565 if (tty
->read_head
== tty
->canon_head
)
570 * isig - handle the ISIG optio
573 * @flush: force flush
575 * Called when a signal is being sent due to terminal input. This
576 * may caus terminal flushing to take place according to the termios
577 * settings and character used. Called from the driver receive_buf
578 * path so serialized.
581 static inline void isig(int sig
, struct tty_struct
*tty
, int flush
)
584 kill_pgrp(tty
->pgrp
, sig
, 1);
585 if (flush
|| !L_NOFLSH(tty
)) {
586 n_tty_flush_buffer(tty
);
587 tty_driver_flush_buffer(tty
);
592 * n_tty_receive_break - handle break
595 * An RS232 break event has been hit in the incoming bitstream. This
596 * can cause a variety of events depending upon the termios settings.
598 * Called from the receive_buf path so single threaded.
601 static inline void n_tty_receive_break(struct tty_struct
*tty
)
606 isig(SIGINT
, tty
, 1);
610 put_tty_queue('\377', tty
);
611 put_tty_queue('\0', tty
);
613 put_tty_queue('\0', tty
);
614 wake_up_interruptible(&tty
->read_wait
);
618 * n_tty_receive_overrun - handle overrun reporting
621 * Data arrived faster than we could process it. While the tty
622 * driver has flagged this the bits that were missed are gone
625 * Called from the receive_buf path so single threaded. Does not
626 * need locking as num_overrun and overrun_time are function
630 static inline void n_tty_receive_overrun(struct tty_struct
*tty
)
635 if (time_before(tty
->overrun_time
, jiffies
- HZ
) ||
636 time_after(tty
->overrun_time
, jiffies
)) {
637 printk(KERN_WARNING
"%s: %d input overrun(s)\n",
640 tty
->overrun_time
= jiffies
;
641 tty
->num_overrun
= 0;
646 * n_tty_receive_parity_error - error notifier
647 * @tty: terminal device
650 * Process a parity error and queue the right data to indicate
651 * the error case if necessary. Locking as per n_tty_receive_buf.
653 static inline void n_tty_receive_parity_error(struct tty_struct
*tty
,
659 put_tty_queue('\377', tty
);
660 put_tty_queue('\0', tty
);
661 put_tty_queue(c
, tty
);
662 } else if (I_INPCK(tty
))
663 put_tty_queue('\0', tty
);
665 put_tty_queue(c
, tty
);
666 wake_up_interruptible(&tty
->read_wait
);
670 * n_tty_receive_char - perform processing
671 * @tty: terminal device
674 * Process an individual character of input received from the driver.
675 * This is serialized with respect to itself by the rules for the
679 static inline void n_tty_receive_char(struct tty_struct
*tty
, unsigned char c
)
684 put_tty_queue(c
, tty
);
690 if (I_IUCLC(tty
) && L_IEXTEN(tty
))
693 if (tty
->stopped
&& !tty
->flow_stopped
&& I_IXON(tty
) &&
694 ((I_IXANY(tty
) && c
!= START_CHAR(tty
) && c
!= STOP_CHAR(tty
)) ||
695 c
== INTR_CHAR(tty
) || c
== QUIT_CHAR(tty
) || c
== SUSP_CHAR(tty
)))
700 if (c
== START_CHAR(tty
))
702 else if (c
== STOP_CHAR(tty
))
709 * If the previous character was LNEXT, or we know that this
710 * character is not one of the characters that we'll have to
711 * handle specially, do shortcut processing to speed things
714 if (!test_bit(c
, tty
->process_char_map
) || tty
->lnext
) {
718 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1) {
719 tty_put_char(tty
, '\a'); /* beep if no space */
722 /* Record the column of first canon char. */
723 if (tty
->canon_head
== tty
->read_head
)
724 tty
->canon_column
= tty
->column
;
727 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
728 put_tty_queue(c
, tty
);
729 put_tty_queue(c
, tty
);
734 if (c
== START_CHAR(tty
)) {
738 if (c
== STOP_CHAR(tty
)) {
747 if (c
== INTR_CHAR(tty
))
750 if (c
== QUIT_CHAR(tty
))
753 if (c
== SUSP_CHAR(tty
)) {
756 * Echo character, and then send the signal.
757 * Note that we do not use isig() here because we want
759 * 1) flush, 2) echo, 3) signal
761 if (!L_NOFLSH(tty
)) {
762 n_tty_flush_buffer(tty
);
763 tty_driver_flush_buffer(tty
);
768 kill_pgrp(tty
->pgrp
, signal
, 1);
778 } else if (c
== '\n' && I_INLCR(tty
))
782 if (c
== ERASE_CHAR(tty
) || c
== KILL_CHAR(tty
) ||
783 (c
== WERASE_CHAR(tty
) && L_IEXTEN(tty
))) {
787 if (c
== LNEXT_CHAR(tty
) && L_IEXTEN(tty
)) {
791 if (L_ECHOCTL(tty
)) {
792 tty_put_char(tty
, '^');
793 tty_put_char(tty
, '\b');
798 if (c
== REPRINT_CHAR(tty
) && L_ECHO(tty
) &&
800 unsigned long tail
= tty
->canon_head
;
805 while (tail
!= tty
->read_head
) {
806 echo_char(tty
->read_buf
[tail
], tty
);
807 tail
= (tail
+1) & (N_TTY_BUF_SIZE
-1);
812 if (L_ECHO(tty
) || L_ECHONL(tty
)) {
813 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1)
814 tty_put_char(tty
, '\a');
819 if (c
== EOF_CHAR(tty
)) {
820 if (tty
->canon_head
!= tty
->read_head
)
821 set_bit(TTY_PUSH
, &tty
->flags
);
825 if ((c
== EOL_CHAR(tty
)) ||
826 (c
== EOL2_CHAR(tty
) && L_IEXTEN(tty
))) {
828 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
831 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1)
832 tty_put_char(tty
, '\a');
833 /* Record the column of first canon char. */
834 if (tty
->canon_head
== tty
->read_head
)
835 tty
->canon_column
= tty
->column
;
839 * XXX does PARMRK doubling happen for
840 * EOL_CHAR and EOL2_CHAR?
842 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
843 put_tty_queue(c
, tty
);
846 spin_lock_irqsave(&tty
->read_lock
, flags
);
847 set_bit(tty
->read_head
, tty
->read_flags
);
848 put_tty_queue_nolock(c
, tty
);
849 tty
->canon_head
= tty
->read_head
;
851 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
852 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
853 if (waitqueue_active(&tty
->read_wait
))
854 wake_up_interruptible(&tty
->read_wait
);
861 if (tty
->read_cnt
>= N_TTY_BUF_SIZE
-1) {
862 tty_put_char(tty
, '\a'); /* beep if no space */
868 /* Record the column of first canon char. */
869 if (tty
->canon_head
== tty
->read_head
)
870 tty
->canon_column
= tty
->column
;
875 if (I_PARMRK(tty
) && c
== (unsigned char) '\377')
876 put_tty_queue(c
, tty
);
878 put_tty_queue(c
, tty
);
883 * n_tty_write_wakeup - asynchronous I/O notifier
886 * Required for the ptys, serial driver etc. since processes
887 * that attach themselves to the master and rely on ASYNC
888 * IO must be woken up
891 static void n_tty_write_wakeup(struct tty_struct
*tty
)
894 set_bit(TTY_DO_WRITE_WAKEUP
, &tty
->flags
);
895 kill_fasync(&tty
->fasync
, SIGIO
, POLL_OUT
);
900 * n_tty_receive_buf - data receive
901 * @tty: terminal device
906 * Called by the terminal driver when a block of characters has
907 * been received. This function must be called from soft contexts
908 * not from interrupt context. The driver is responsible for making
909 * calls one at a time and in order (or using flush_to_ldisc)
912 static void n_tty_receive_buf(struct tty_struct
*tty
, const unsigned char *cp
,
915 const unsigned char *p
;
916 char *f
, flags
= TTY_NORMAL
;
919 unsigned long cpuflags
;
925 spin_lock_irqsave(&tty
->read_lock
, cpuflags
);
926 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
927 N_TTY_BUF_SIZE
- tty
->read_head
);
929 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
930 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
935 i
= min(N_TTY_BUF_SIZE
- tty
->read_cnt
,
936 N_TTY_BUF_SIZE
- tty
->read_head
);
938 memcpy(tty
->read_buf
+ tty
->read_head
, cp
, i
);
939 tty
->read_head
= (tty
->read_head
+ i
) & (N_TTY_BUF_SIZE
-1);
941 spin_unlock_irqrestore(&tty
->read_lock
, cpuflags
);
943 for (i
= count
, p
= cp
, f
= fp
; i
; i
--, p
++) {
948 n_tty_receive_char(tty
, *p
);
951 n_tty_receive_break(tty
);
955 n_tty_receive_parity_error(tty
, *p
);
958 n_tty_receive_overrun(tty
);
961 printk(KERN_ERR
"%s: unknown flag %d\n",
962 tty_name(tty
, buf
), flags
);
966 if (tty
->ops
->flush_chars
)
967 tty
->ops
->flush_chars(tty
);
972 if (!tty
->icanon
&& (tty
->read_cnt
>= tty
->minimum_to_wake
)) {
973 kill_fasync(&tty
->fasync
, SIGIO
, POLL_IN
);
974 if (waitqueue_active(&tty
->read_wait
))
975 wake_up_interruptible(&tty
->read_wait
);
979 * Check the remaining room for the input canonicalization
980 * mode. We don't want to throttle the driver if we're in
981 * canonical mode and don't have a newline yet!
983 if (tty
->receive_room
< TTY_THRESHOLD_THROTTLE
)
987 int is_ignored(int sig
)
989 return (sigismember(¤t
->blocked
, sig
) ||
990 current
->sighand
->action
[sig
-1].sa
.sa_handler
== SIG_IGN
);
994 * n_tty_set_termios - termios data changed
996 * @old: previous data
998 * Called by the tty layer when the user changes termios flags so
999 * that the line discipline can plan ahead. This function cannot sleep
1000 * and is protected from re-entry by the tty layer. The user is
1001 * guaranteed that this function will not be re-entered or in progress
1002 * when the ldisc is closed.
1005 static void n_tty_set_termios(struct tty_struct
*tty
, struct ktermios
*old
)
1010 tty
->icanon
= (L_ICANON(tty
) != 0);
1011 if (test_bit(TTY_HW_COOK_IN
, &tty
->flags
)) {
1014 n_tty_set_room(tty
);
1017 if (I_ISTRIP(tty
) || I_IUCLC(tty
) || I_IGNCR(tty
) ||
1018 I_ICRNL(tty
) || I_INLCR(tty
) || L_ICANON(tty
) ||
1019 I_IXON(tty
) || L_ISIG(tty
) || L_ECHO(tty
) ||
1021 memset(tty
->process_char_map
, 0, 256/8);
1023 if (I_IGNCR(tty
) || I_ICRNL(tty
))
1024 set_bit('\r', tty
->process_char_map
);
1026 set_bit('\n', tty
->process_char_map
);
1028 if (L_ICANON(tty
)) {
1029 set_bit(ERASE_CHAR(tty
), tty
->process_char_map
);
1030 set_bit(KILL_CHAR(tty
), tty
->process_char_map
);
1031 set_bit(EOF_CHAR(tty
), tty
->process_char_map
);
1032 set_bit('\n', tty
->process_char_map
);
1033 set_bit(EOL_CHAR(tty
), tty
->process_char_map
);
1034 if (L_IEXTEN(tty
)) {
1035 set_bit(WERASE_CHAR(tty
),
1036 tty
->process_char_map
);
1037 set_bit(LNEXT_CHAR(tty
),
1038 tty
->process_char_map
);
1039 set_bit(EOL2_CHAR(tty
),
1040 tty
->process_char_map
);
1042 set_bit(REPRINT_CHAR(tty
),
1043 tty
->process_char_map
);
1047 set_bit(START_CHAR(tty
), tty
->process_char_map
);
1048 set_bit(STOP_CHAR(tty
), tty
->process_char_map
);
1051 set_bit(INTR_CHAR(tty
), tty
->process_char_map
);
1052 set_bit(QUIT_CHAR(tty
), tty
->process_char_map
);
1053 set_bit(SUSP_CHAR(tty
), tty
->process_char_map
);
1055 clear_bit(__DISABLED_CHAR
, tty
->process_char_map
);
1060 if ((I_IGNBRK(tty
) || (!I_BRKINT(tty
) && !I_PARMRK(tty
))) &&
1061 (I_IGNPAR(tty
) || !I_INPCK(tty
)) &&
1062 (tty
->driver
->flags
& TTY_DRIVER_REAL_RAW
))
1067 n_tty_set_room(tty
);
1068 /* The termios change make the tty ready for I/O */
1069 wake_up_interruptible(&tty
->write_wait
);
1070 wake_up_interruptible(&tty
->read_wait
);
1074 * n_tty_close - close the ldisc for this tty
1077 * Called from the terminal layer when this line discipline is
1078 * being shut down, either because of a close or becsuse of a
1079 * discipline change. The function will not be called while other
1080 * ldisc methods are in progress.
1083 static void n_tty_close(struct tty_struct
*tty
)
1085 n_tty_flush_buffer(tty
);
1086 if (tty
->read_buf
) {
1087 free_buf(tty
->read_buf
);
1088 tty
->read_buf
= NULL
;
1093 * n_tty_open - open an ldisc
1094 * @tty: terminal to open
1096 * Called when this line discipline is being attached to the
1097 * terminal device. Can sleep. Called serialized so that no
1098 * other events will occur in parallel. No further open will occur
1102 static int n_tty_open(struct tty_struct
*tty
)
1107 /* This one is ugly. Currently a malloc failure here can panic */
1108 if (!tty
->read_buf
) {
1109 tty
->read_buf
= alloc_buf();
1113 memset(tty
->read_buf
, 0, N_TTY_BUF_SIZE
);
1114 reset_buffer_flags(tty
);
1116 n_tty_set_termios(tty
, NULL
);
1117 tty
->minimum_to_wake
= 1;
1122 static inline int input_available_p(struct tty_struct
*tty
, int amt
)
1125 if (tty
->canon_data
)
1127 } else if (tty
->read_cnt
>= (amt
? amt
: 1))
1134 * copy_from_read_buf - copy read data directly
1135 * @tty: terminal device
1139 * Helper function to speed up read_chan. It is only called when
1140 * ICANON is off; it copies characters straight from the tty queue to
1141 * user space directly. It can be profitably called twice; once to
1142 * drain the space from the tail pointer to the (physical) end of the
1143 * buffer, and once to drain the space from the (physical) beginning of
1144 * the buffer to head pointer.
1146 * Called under the tty->atomic_read_lock sem
1150 static int copy_from_read_buf(struct tty_struct
*tty
,
1151 unsigned char __user
**b
,
1157 unsigned long flags
;
1160 spin_lock_irqsave(&tty
->read_lock
, flags
);
1161 n
= min(tty
->read_cnt
, N_TTY_BUF_SIZE
- tty
->read_tail
);
1163 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1165 retval
= copy_to_user(*b
, &tty
->read_buf
[tty
->read_tail
], n
);
1167 tty_audit_add_data(tty
, &tty
->read_buf
[tty
->read_tail
], n
);
1168 spin_lock_irqsave(&tty
->read_lock
, flags
);
1169 tty
->read_tail
= (tty
->read_tail
+ n
) & (N_TTY_BUF_SIZE
-1);
1171 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1178 extern ssize_t
redirected_tty_write(struct file
*, const char __user
*,
1182 * job_control - check job control
1184 * @file: file handle
1186 * Perform job control management checks on this file/tty descriptor
1187 * and if appropriate send any needed signals and return a negative
1188 * error code if action should be taken.
1191 * Locking: None - redirected write test is safe, testing
1192 * current->signal should possibly lock current->sighand
1196 static int job_control(struct tty_struct
*tty
, struct file
*file
)
1198 /* Job control check -- must be done at start and after
1199 every sleep (POSIX.1 7.1.1.4). */
1200 /* NOTE: not yet done after every sleep pending a thorough
1201 check of the logic of this change. -- jlc */
1202 /* don't stop on /dev/console */
1203 if (file
->f_op
->write
!= redirected_tty_write
&&
1204 current
->signal
->tty
== tty
) {
1206 printk(KERN_ERR
"read_chan: no tty->pgrp!\n");
1207 else if (task_pgrp(current
) != tty
->pgrp
) {
1208 if (is_ignored(SIGTTIN
) ||
1209 is_current_pgrp_orphaned())
1211 kill_pgrp(task_pgrp(current
), SIGTTIN
, 1);
1212 set_thread_flag(TIF_SIGPENDING
);
1213 return -ERESTARTSYS
;
1221 * read_chan - read function for tty
1223 * @file: file object
1224 * @buf: userspace buffer pointer
1227 * Perform reads for the line discipline. We are guaranteed that the
1228 * line discipline will not be closed under us but we may get multiple
1229 * parallel readers and must handle this ourselves. We may also get
1230 * a hangup. Always called in user context, may sleep.
1232 * This code must be sure never to sleep through a hangup.
1235 static ssize_t
read_chan(struct tty_struct
*tty
, struct file
*file
,
1236 unsigned char __user
*buf
, size_t nr
)
1238 unsigned char __user
*b
= buf
;
1239 DECLARE_WAITQUEUE(wait
, current
);
1245 unsigned long flags
;
1250 if (!tty
->read_buf
) {
1251 printk(KERN_ERR
"n_tty_read_chan: read_buf == NULL?!?\n");
1255 c
= job_control(tty
, file
);
1260 timeout
= MAX_SCHEDULE_TIMEOUT
;
1262 time
= (HZ
/ 10) * TIME_CHAR(tty
);
1263 minimum
= MIN_CHAR(tty
);
1266 tty
->minimum_to_wake
= 1;
1267 else if (!waitqueue_active(&tty
->read_wait
) ||
1268 (tty
->minimum_to_wake
> minimum
))
1269 tty
->minimum_to_wake
= minimum
;
1276 tty
->minimum_to_wake
= minimum
= 1;
1281 * Internal serialization of reads.
1283 if (file
->f_flags
& O_NONBLOCK
) {
1284 if (!mutex_trylock(&tty
->atomic_read_lock
))
1287 if (mutex_lock_interruptible(&tty
->atomic_read_lock
))
1288 return -ERESTARTSYS
;
1290 packet
= tty
->packet
;
1292 add_wait_queue(&tty
->read_wait
, &wait
);
1294 /* First test for status change. */
1295 if (packet
&& tty
->link
->ctrl_status
) {
1299 spin_lock_irqsave(&tty
->link
->ctrl_lock
, flags
);
1300 cs
= tty
->link
->ctrl_status
;
1301 tty
->link
->ctrl_status
= 0;
1302 spin_unlock_irqrestore(&tty
->link
->ctrl_lock
, flags
);
1303 if (tty_put_user(tty
, cs
, b
++)) {
1311 /* This statement must be first before checking for input
1312 so that any interrupt will set the state back to
1314 set_current_state(TASK_INTERRUPTIBLE
);
1316 if (((minimum
- (b
- buf
)) < tty
->minimum_to_wake
) &&
1317 ((minimum
- (b
- buf
)) >= 1))
1318 tty
->minimum_to_wake
= (minimum
- (b
- buf
));
1320 if (!input_available_p(tty
, 0)) {
1321 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
)) {
1325 if (tty_hung_up_p(file
))
1329 if (file
->f_flags
& O_NONBLOCK
) {
1333 if (signal_pending(current
)) {
1334 retval
= -ERESTARTSYS
;
1337 /* FIXME: does n_tty_set_room need locking ? */
1338 n_tty_set_room(tty
);
1339 timeout
= schedule_timeout(timeout
);
1342 __set_current_state(TASK_RUNNING
);
1344 /* Deal with packet mode. */
1345 if (packet
&& b
== buf
) {
1346 if (tty_put_user(tty
, TIOCPKT_DATA
, b
++)) {
1355 /* N.B. avoid overrun if nr == 0 */
1356 while (nr
&& tty
->read_cnt
) {
1359 eol
= test_and_clear_bit(tty
->read_tail
,
1361 c
= tty
->read_buf
[tty
->read_tail
];
1362 spin_lock_irqsave(&tty
->read_lock
, flags
);
1363 tty
->read_tail
= ((tty
->read_tail
+1) &
1364 (N_TTY_BUF_SIZE
-1));
1367 /* this test should be redundant:
1368 * we shouldn't be reading data if
1371 if (--tty
->canon_data
< 0)
1372 tty
->canon_data
= 0;
1374 spin_unlock_irqrestore(&tty
->read_lock
, flags
);
1376 if (!eol
|| (c
!= __DISABLED_CHAR
)) {
1377 if (tty_put_user(tty
, c
, b
++)) {
1385 tty_audit_push(tty
);
1393 /* The copy function takes the read lock and handles
1394 locking internally for this case */
1395 uncopied
= copy_from_read_buf(tty
, &b
, &nr
);
1396 uncopied
+= copy_from_read_buf(tty
, &b
, &nr
);
1403 /* If there is enough space in the read buffer now, let the
1404 * low-level driver know. We use n_tty_chars_in_buffer() to
1405 * check the buffer, as it now knows about canonical mode.
1406 * Otherwise, if the driver is throttled and the line is
1407 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1408 * we won't get any more characters.
1410 if (n_tty_chars_in_buffer(tty
) <= TTY_THRESHOLD_UNTHROTTLE
) {
1411 n_tty_set_room(tty
);
1412 check_unthrottle(tty
);
1415 if (b
- buf
>= minimum
)
1420 mutex_unlock(&tty
->atomic_read_lock
);
1421 remove_wait_queue(&tty
->read_wait
, &wait
);
1423 if (!waitqueue_active(&tty
->read_wait
))
1424 tty
->minimum_to_wake
= minimum
;
1426 __set_current_state(TASK_RUNNING
);
1431 clear_bit(TTY_PUSH
, &tty
->flags
);
1432 } else if (test_and_clear_bit(TTY_PUSH
, &tty
->flags
))
1435 n_tty_set_room(tty
);
1440 * write_chan - write function for tty
1442 * @file: file object
1443 * @buf: userspace buffer pointer
1446 * Write function of the terminal device. This is serialized with
1447 * respect to other write callers but not to termios changes, reads
1448 * and other such events. We must be careful with N_TTY as the receive
1449 * code will echo characters, thus calling driver write methods.
1451 * This code must be sure never to sleep through a hangup.
1454 static ssize_t
write_chan(struct tty_struct
*tty
, struct file
*file
,
1455 const unsigned char *buf
, size_t nr
)
1457 const unsigned char *b
= buf
;
1458 DECLARE_WAITQUEUE(wait
, current
);
1462 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1463 if (L_TOSTOP(tty
) && file
->f_op
->write
!= redirected_tty_write
) {
1464 retval
= tty_check_change(tty
);
1469 add_wait_queue(&tty
->write_wait
, &wait
);
1471 set_current_state(TASK_INTERRUPTIBLE
);
1472 if (signal_pending(current
)) {
1473 retval
= -ERESTARTSYS
;
1476 if (tty_hung_up_p(file
) || (tty
->link
&& !tty
->link
->count
)) {
1480 if (O_OPOST(tty
) && !(test_bit(TTY_HW_COOK_OUT
, &tty
->flags
))) {
1482 ssize_t num
= opost_block(tty
, b
, nr
);
1494 if (opost(c
, tty
) < 0)
1498 if (tty
->ops
->flush_chars
)
1499 tty
->ops
->flush_chars(tty
);
1502 c
= tty
->ops
->write(tty
, b
, nr
);
1515 if (file
->f_flags
& O_NONBLOCK
) {
1522 __set_current_state(TASK_RUNNING
);
1523 remove_wait_queue(&tty
->write_wait
, &wait
);
1524 return (b
- buf
) ? b
- buf
: retval
;
1528 * normal_poll - poll method for N_TTY
1529 * @tty: terminal device
1530 * @file: file accessing it
1533 * Called when the line discipline is asked to poll() for data or
1534 * for special events. This code is not serialized with respect to
1535 * other events save open/close.
1537 * This code must be sure never to sleep through a hangup.
1538 * Called without the kernel lock held - fine
1541 static unsigned int normal_poll(struct tty_struct
*tty
, struct file
*file
,
1544 unsigned int mask
= 0;
1546 poll_wait(file
, &tty
->read_wait
, wait
);
1547 poll_wait(file
, &tty
->write_wait
, wait
);
1548 if (input_available_p(tty
, TIME_CHAR(tty
) ? 0 : MIN_CHAR(tty
)))
1549 mask
|= POLLIN
| POLLRDNORM
;
1550 if (tty
->packet
&& tty
->link
->ctrl_status
)
1551 mask
|= POLLPRI
| POLLIN
| POLLRDNORM
;
1552 if (test_bit(TTY_OTHER_CLOSED
, &tty
->flags
))
1554 if (tty_hung_up_p(file
))
1556 if (!(mask
& (POLLHUP
| POLLIN
| POLLRDNORM
))) {
1557 if (MIN_CHAR(tty
) && !TIME_CHAR(tty
))
1558 tty
->minimum_to_wake
= MIN_CHAR(tty
);
1560 tty
->minimum_to_wake
= 1;
1562 if (tty
->ops
->write
&& !tty_is_writelocked(tty
) &&
1563 tty_chars_in_buffer(tty
) < WAKEUP_CHARS
&&
1564 tty_write_room(tty
) > 0)
1565 mask
|= POLLOUT
| POLLWRNORM
;
1569 struct tty_ldisc tty_ldisc_N_TTY
= {
1570 .magic
= TTY_LDISC_MAGIC
,
1573 .close
= n_tty_close
,
1574 .flush_buffer
= n_tty_flush_buffer
,
1575 .chars_in_buffer
= n_tty_chars_in_buffer
,
1577 .write
= write_chan
,
1578 .ioctl
= n_tty_ioctl
,
1579 .set_termios
= n_tty_set_termios
,
1580 .poll
= normal_poll
,
1581 .receive_buf
= n_tty_receive_buf
,
1582 .write_wakeup
= n_tty_write_wakeup