2
* n_tty.c --- implements the N_TTY line discipline.
4
* This code used to be in tty_io.c, but things are getting hairy
5
* enough that it made sense to split things off. (The N_TTY
6
* processing has changed so much that it's hardly recognizable,
9
* Note that the open routine for N_TTY is guaranteed never to return
10
* an error. This is because Linux will fall back to setting a line
11
* to N_TTY if it can not switch to any other line discipline.
13
* Written by Theodore Ts'o, Copyright 1994.
15
* This file also contains code originally written by Linus Torvalds,
16
* Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18
* This file may be redistributed under the terms of the GNU General Public
21
* Reduced memory usage for older ARM systems - Russell King.
23
* 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
24
* the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25
* who actually finally proved there really was a race.
27
* 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28
* waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29
* Also fixed a bug in BLOCKING mode where n_tty_write returns
33
#include <linux/types.h>
34
#include <linux/major.h>
35
#include <linux/errno.h>
36
#include <linux/signal.h>
37
#include <linux/fcntl.h>
38
#include <linux/sched.h>
39
#include <linux/interrupt.h>
40
#include <linux/tty.h>
41
#include <linux/timer.h>
42
#include <linux/ctype.h>
44
#include <linux/string.h>
45
#include <linux/slab.h>
46
#include <linux/poll.h>
47
#include <linux/bitops.h>
48
#include <linux/audit.h>
49
#include <linux/file.h>
50
#include <linux/uaccess.h>
51
#include <linux/module.h>
53
#include <asm/system.h>
55
/* number of characters left in xmit buffer before select has we have room */
56
#define WAKEUP_CHARS 256
59
* This defines the low- and high-watermarks for throttling and
60
* unthrottling the TTY driver. These watermarks are used for
61
* controlling the space in the read buffer.
63
#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
64
#define TTY_THRESHOLD_UNTHROTTLE 128
67
* Special byte codes used in the echo buffer to represent operations
68
* or special handling of characters. Bytes in the echo buffer that
69
* are not part of such special blocks are treated as normal character
72
#define ECHO_OP_START 0xff
73
#define ECHO_OP_MOVE_BACK_COL 0x80
74
#define ECHO_OP_SET_CANON_COL 0x81
75
#define ECHO_OP_ERASE_TAB 0x82
77
static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
78
unsigned char __user *ptr)
80
tty_audit_add_data(tty, &x, 1);
81
return put_user(x, ptr);
85
* n_tty_set__room - receive space
88
* Called by the driver to find out how much data it is
89
* permitted to feed to the line discipline without any being lost
90
* and thus to manage flow control. Not serialized. Answers for the
94
static void n_tty_set_room(struct tty_struct *tty)
96
/* tty->read_cnt is not read locked ? */
97
int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
100
* If we are doing input canonicalization, and there are no
101
* pending newlines, let characters through without limit, so
102
* that erase characters will be handled. Other excess
103
* characters will be beeped.
106
left = tty->icanon && !tty->canon_data;
107
tty->receive_room = left;
110
static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
112
if (tty->read_cnt < N_TTY_BUF_SIZE) {
113
tty->read_buf[tty->read_head] = c;
114
tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1);
120
* put_tty_queue - add character to tty
124
* Add a character to the tty read_buf queue. This is done under the
125
* read_lock to serialize character addition and also to protect us
126
* against parallel reads or flushes
129
static void put_tty_queue(unsigned char c, struct tty_struct *tty)
133
* The problem of stomping on the buffers ends here.
134
* Why didn't anyone see this one coming? --AJK
136
spin_lock_irqsave(&tty->read_lock, flags);
137
put_tty_queue_nolock(c, tty);
138
spin_unlock_irqrestore(&tty->read_lock, flags);
142
* check_unthrottle - allow new receive data
145
* Check whether to call the driver unthrottle functions
147
* Can sleep, may be called under the atomic_read_lock mutex but
148
* this is not guaranteed.
150
static void check_unthrottle(struct tty_struct *tty)
157
* reset_buffer_flags - reset buffer state
158
* @tty: terminal to reset
160
* Reset the read buffer counters, clear the flags,
161
* and make sure the driver is unthrottled. Called
162
* from n_tty_open() and n_tty_flush_buffer().
164
* Locking: tty_read_lock for read fields.
167
static void reset_buffer_flags(struct tty_struct *tty)
171
spin_lock_irqsave(&tty->read_lock, flags);
172
tty->read_head = tty->read_tail = tty->read_cnt = 0;
173
spin_unlock_irqrestore(&tty->read_lock, flags);
175
mutex_lock(&tty->echo_lock);
176
tty->echo_pos = tty->echo_cnt = tty->echo_overrun = 0;
177
mutex_unlock(&tty->echo_lock);
179
tty->canon_head = tty->canon_data = tty->erasing = 0;
180
memset(&tty->read_flags, 0, sizeof tty->read_flags);
182
check_unthrottle(tty);
186
* n_tty_flush_buffer - clean input queue
187
* @tty: terminal device
189
* Flush the input buffer. Called when the line discipline is
190
* being closed, when the tty layer wants the buffer flushed (eg
191
* at hangup) or when the N_TTY line discipline internally has to
192
* clean the pending queue (for example some signals).
194
* Locking: ctrl_lock, read_lock.
197
static void n_tty_flush_buffer(struct tty_struct *tty)
200
/* clear everything and unthrottle the driver */
201
reset_buffer_flags(tty);
206
spin_lock_irqsave(&tty->ctrl_lock, flags);
207
if (tty->link->packet) {
208
tty->ctrl_status |= TIOCPKT_FLUSHREAD;
209
wake_up_interruptible(&tty->link->read_wait);
211
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
215
* n_tty_chars_in_buffer - report available bytes
218
* Report the number of characters buffered to be delivered to user
219
* at this instant in time.
224
static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
229
spin_lock_irqsave(&tty->read_lock, flags);
232
} else if (tty->canon_data) {
233
n = (tty->canon_head > tty->read_tail) ?
234
tty->canon_head - tty->read_tail :
235
tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail);
237
spin_unlock_irqrestore(&tty->read_lock, flags);
242
* is_utf8_continuation - utf8 multibyte check
245
* Returns true if the utf8 character 'c' is a multibyte continuation
246
* character. We use this to correctly compute the on screen size
247
* of the character when printing
250
static inline int is_utf8_continuation(unsigned char c)
252
return (c & 0xc0) == 0x80;
256
* is_continuation - multibyte check
259
* Returns true if the utf8 character 'c' is a multibyte continuation
260
* character and the terminal is in unicode mode.
263
static inline int is_continuation(unsigned char c, struct tty_struct *tty)
265
return I_IUTF8(tty) && is_utf8_continuation(c);
269
* do_output_char - output one character
270
* @c: character (or partial unicode symbol)
271
* @tty: terminal device
272
* @space: space available in tty driver write buffer
274
* This is a helper function that handles one output character
275
* (including special characters like TAB, CR, LF, etc.),
276
* doing OPOST processing and putting the results in the
277
* tty driver's write buffer.
279
* Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
280
* and NLDLY. They simply aren't relevant in the world today.
281
* If you ever need them, add them here.
283
* Returns the number of bytes of buffer space used or -1 if
286
* Locking: should be called under the output_lock to protect
287
* the column state and space left in the buffer
290
static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
304
tty->canon_column = tty->column = 0;
305
tty->ops->write(tty, "\r\n", 2);
308
tty->canon_column = tty->column;
311
if (O_ONOCR(tty) && tty->column == 0)
316
tty->canon_column = tty->column = 0;
319
tty->canon_column = tty->column = 0;
322
spaces = 8 - (tty->column & 7);
323
if (O_TABDLY(tty) == XTABS) {
326
tty->column += spaces;
327
tty->ops->write(tty, " ", spaces);
330
tty->column += spaces;
340
if (!is_continuation(c, tty))
346
tty_put_char(tty, c);
351
* process_output - output post processor
352
* @c: character (or partial unicode symbol)
353
* @tty: terminal device
355
* Output one character with OPOST processing.
356
* Returns -1 when the output device is full and the character
359
* Locking: output_lock to protect column state and space left
360
* (also, this is called from n_tty_write under the
361
* tty layer write lock)
364
static int process_output(unsigned char c, struct tty_struct *tty)
368
mutex_lock(&tty->output_lock);
370
space = tty_write_room(tty);
371
retval = do_output_char(c, tty, space);
373
mutex_unlock(&tty->output_lock);
381
* process_output_block - block post processor
382
* @tty: terminal device
383
* @buf: character buffer
384
* @nr: number of bytes to output
386
* Output a block of characters with OPOST processing.
387
* Returns the number of characters output.
389
* This path is used to speed up block console writes, among other
390
* things when processing blocks of output data. It handles only
391
* the simple cases normally found and helps to generate blocks of
392
* symbols for the console driver and thus improve performance.
394
* Locking: output_lock to protect column state and space left
395
* (also, this is called from n_tty_write under the
396
* tty layer write lock)
399
static ssize_t process_output_block(struct tty_struct *tty,
400
const unsigned char *buf, unsigned int nr)
404
const unsigned char *cp;
406
mutex_lock(&tty->output_lock);
408
space = tty_write_room(tty);
410
mutex_unlock(&tty->output_lock);
416
for (i = 0, cp = buf; i < nr; i++, cp++) {
417
unsigned char c = *cp;
425
tty->canon_column = tty->column;
428
if (O_ONOCR(tty) && tty->column == 0)
432
tty->canon_column = tty->column = 0;
444
if (!is_continuation(c, tty))
451
i = tty->ops->write(tty, buf, i);
453
mutex_unlock(&tty->output_lock);
458
* process_echoes - write pending echo characters
459
* @tty: terminal device
461
* Write previously buffered echo (and other ldisc-generated)
462
* characters to the tty.
464
* Characters generated by the ldisc (including echoes) need to
465
* be buffered because the driver's write buffer can fill during
466
* heavy program output. Echoing straight to the driver will
467
* often fail under these conditions, causing lost characters and
468
* resulting mismatches of ldisc state information.
470
* Since the ldisc state must represent the characters actually sent
471
* to the driver at the time of the write, operations like certain
472
* changes in column state are also saved in the buffer and executed
475
* A circular fifo buffer is used so that the most recent characters
476
* are prioritized. Also, when control characters are echoed with a
477
* prefixed "^", the pair is treated atomically and thus not separated.
479
* Locking: output_lock to protect column state and space left,
480
* echo_lock to protect the echo buffer
483
static void process_echoes(struct tty_struct *tty)
487
unsigned char *cp, *buf_end;
492
mutex_lock(&tty->output_lock);
493
mutex_lock(&tty->echo_lock);
495
space = tty_write_room(tty);
497
buf_end = tty->echo_buf + N_TTY_BUF_SIZE;
498
cp = tty->echo_buf + tty->echo_pos;
502
if (c == ECHO_OP_START) {
505
int no_space_left = 0;
508
* If the buffer byte is the start of a multi-byte
509
* operation, get the next byte, which is either the
510
* op code or a control character value.
514
opp -= N_TTY_BUF_SIZE;
518
unsigned int num_chars, num_bs;
520
case ECHO_OP_ERASE_TAB:
521
if (++opp == buf_end)
522
opp -= N_TTY_BUF_SIZE;
526
* Determine how many columns to go back
527
* in order to erase the tab.
528
* This depends on the number of columns
529
* used by other characters within the tab
530
* area. If this (modulo 8) count is from
531
* the start of input rather than from a
532
* previous tab, we offset by canon column.
533
* Otherwise, tab spacing is normal.
535
if (!(num_chars & 0x80))
536
num_chars += tty->canon_column;
537
num_bs = 8 - (num_chars & 7);
539
if (num_bs > space) {
545
tty_put_char(tty, '\b');
553
case ECHO_OP_SET_CANON_COL:
554
tty->canon_column = tty->column;
559
case ECHO_OP_MOVE_BACK_COL:
567
/* This is an escaped echo op start code */
572
tty_put_char(tty, ECHO_OP_START);
581
* If the op is not a special byte code,
582
* it is a ctrl char tagged to be echoed
583
* as "^X" (where X is the letter
584
* representing the control char).
585
* Note that we must ensure there is
586
* enough space for the whole ctrl pair.
593
tty_put_char(tty, '^');
594
tty_put_char(tty, op ^ 0100);
605
!(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
606
int retval = do_output_char(c, tty, space);
613
tty_put_char(tty, c);
620
/* When end of circular buffer reached, wrap around */
622
cp -= N_TTY_BUF_SIZE;
628
tty->echo_overrun = 0;
630
int num_processed = tty->echo_cnt - nr;
631
tty->echo_pos += num_processed;
632
tty->echo_pos &= N_TTY_BUF_SIZE - 1;
634
if (num_processed > 0)
635
tty->echo_overrun = 0;
638
mutex_unlock(&tty->echo_lock);
639
mutex_unlock(&tty->output_lock);
641
if (tty->ops->flush_chars)
642
tty->ops->flush_chars(tty);
646
* add_echo_byte - add a byte to the echo buffer
647
* @c: unicode byte to echo
648
* @tty: terminal device
650
* Add a character or operation byte to the echo buffer.
652
* Should be called under the echo lock to protect the echo buffer.
655
static void add_echo_byte(unsigned char c, struct tty_struct *tty)
659
if (tty->echo_cnt == N_TTY_BUF_SIZE) {
660
/* Circular buffer is already at capacity */
661
new_byte_pos = tty->echo_pos;
664
* Since the buffer start position needs to be advanced,
665
* be sure to step by a whole operation byte group.
667
if (tty->echo_buf[tty->echo_pos] == ECHO_OP_START) {
668
if (tty->echo_buf[(tty->echo_pos + 1) &
669
(N_TTY_BUF_SIZE - 1)] ==
680
tty->echo_pos &= N_TTY_BUF_SIZE - 1;
682
tty->echo_overrun = 1;
684
new_byte_pos = tty->echo_pos + tty->echo_cnt;
685
new_byte_pos &= N_TTY_BUF_SIZE - 1;
689
tty->echo_buf[new_byte_pos] = c;
693
* echo_move_back_col - add operation to move back a column
694
* @tty: terminal device
696
* Add an operation to the echo buffer to move back one column.
698
* Locking: echo_lock to protect the echo buffer
701
static void echo_move_back_col(struct tty_struct *tty)
703
mutex_lock(&tty->echo_lock);
705
add_echo_byte(ECHO_OP_START, tty);
706
add_echo_byte(ECHO_OP_MOVE_BACK_COL, tty);
708
mutex_unlock(&tty->echo_lock);
712
* echo_set_canon_col - add operation to set the canon column
713
* @tty: terminal device
715
* Add an operation to the echo buffer to set the canon column
716
* to the current column.
718
* Locking: echo_lock to protect the echo buffer
721
static void echo_set_canon_col(struct tty_struct *tty)
723
mutex_lock(&tty->echo_lock);
725
add_echo_byte(ECHO_OP_START, tty);
726
add_echo_byte(ECHO_OP_SET_CANON_COL, tty);
728
mutex_unlock(&tty->echo_lock);
732
* echo_erase_tab - add operation to erase a tab
733
* @num_chars: number of character columns already used
734
* @after_tab: true if num_chars starts after a previous tab
735
* @tty: terminal device
737
* Add an operation to the echo buffer to erase a tab.
739
* Called by the eraser function, which knows how many character
740
* columns have been used since either a previous tab or the start
741
* of input. This information will be used later, along with
742
* canon column (if applicable), to go back the correct number
745
* Locking: echo_lock to protect the echo buffer
748
static void echo_erase_tab(unsigned int num_chars, int after_tab,
749
struct tty_struct *tty)
751
mutex_lock(&tty->echo_lock);
753
add_echo_byte(ECHO_OP_START, tty);
754
add_echo_byte(ECHO_OP_ERASE_TAB, tty);
756
/* We only need to know this modulo 8 (tab spacing) */
759
/* Set the high bit as a flag if num_chars is after a previous tab */
763
add_echo_byte(num_chars, tty);
765
mutex_unlock(&tty->echo_lock);
769
* echo_char_raw - echo a character raw
770
* @c: unicode byte to echo
771
* @tty: terminal device
773
* Echo user input back onto the screen. This must be called only when
774
* L_ECHO(tty) is true. Called from the driver receive_buf path.
776
* This variant does not treat control characters specially.
778
* Locking: echo_lock to protect the echo buffer
781
static void echo_char_raw(unsigned char c, struct tty_struct *tty)
783
mutex_lock(&tty->echo_lock);
785
if (c == ECHO_OP_START) {
786
add_echo_byte(ECHO_OP_START, tty);
787
add_echo_byte(ECHO_OP_START, tty);
789
add_echo_byte(c, tty);
792
mutex_unlock(&tty->echo_lock);
796
* echo_char - echo a character
797
* @c: unicode byte to echo
798
* @tty: terminal device
800
* Echo user input back onto the screen. This must be called only when
801
* L_ECHO(tty) is true. Called from the driver receive_buf path.
803
* This variant tags control characters to be echoed as "^X"
804
* (where X is the letter representing the control char).
806
* Locking: echo_lock to protect the echo buffer
809
static void echo_char(unsigned char c, struct tty_struct *tty)
811
mutex_lock(&tty->echo_lock);
813
if (c == ECHO_OP_START) {
814
add_echo_byte(ECHO_OP_START, tty);
815
add_echo_byte(ECHO_OP_START, tty);
817
if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
818
add_echo_byte(ECHO_OP_START, tty);
819
add_echo_byte(c, tty);
822
mutex_unlock(&tty->echo_lock);
826
* finish_erasing - complete erase
827
* @tty: tty doing the erase
830
static inline void finish_erasing(struct tty_struct *tty)
833
echo_char_raw('/', tty);
839
* eraser - handle erase function
840
* @c: character input
841
* @tty: terminal device
843
* Perform erase and necessary output when an erase character is
844
* present in the stream from the driver layer. Handles the complexities
845
* of UTF-8 multibyte symbols.
847
* Locking: read_lock for tty buffers
850
static void eraser(unsigned char c, struct tty_struct *tty)
852
enum { ERASE, WERASE, KILL } kill_type;
853
int head, seen_alnums, cnt;
856
/* FIXME: locking needed ? */
857
if (tty->read_head == tty->canon_head) {
858
/* process_output('\a', tty); */ /* what do you think? */
861
if (c == ERASE_CHAR(tty))
863
else if (c == WERASE_CHAR(tty))
867
spin_lock_irqsave(&tty->read_lock, flags);
868
tty->read_cnt -= ((tty->read_head - tty->canon_head) &
869
(N_TTY_BUF_SIZE - 1));
870
tty->read_head = tty->canon_head;
871
spin_unlock_irqrestore(&tty->read_lock, flags);
874
if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
875
spin_lock_irqsave(&tty->read_lock, flags);
876
tty->read_cnt -= ((tty->read_head - tty->canon_head) &
877
(N_TTY_BUF_SIZE - 1));
878
tty->read_head = tty->canon_head;
879
spin_unlock_irqrestore(&tty->read_lock, flags);
881
echo_char(KILL_CHAR(tty), tty);
882
/* Add a newline if ECHOK is on and ECHOKE is off. */
884
echo_char_raw('\n', tty);
891
/* FIXME: Locking ?? */
892
while (tty->read_head != tty->canon_head) {
893
head = tty->read_head;
895
/* erase a single possibly multibyte character */
897
head = (head - 1) & (N_TTY_BUF_SIZE-1);
898
c = tty->read_buf[head];
899
} while (is_continuation(c, tty) && head != tty->canon_head);
901
/* do not partially erase */
902
if (is_continuation(c, tty))
905
if (kill_type == WERASE) {
906
/* Equivalent to BSD's ALTWERASE. */
907
if (isalnum(c) || c == '_')
909
else if (seen_alnums)
912
cnt = (tty->read_head - head) & (N_TTY_BUF_SIZE-1);
913
spin_lock_irqsave(&tty->read_lock, flags);
914
tty->read_head = head;
915
tty->read_cnt -= cnt;
916
spin_unlock_irqrestore(&tty->read_lock, flags);
918
if (L_ECHOPRT(tty)) {
920
echo_char_raw('\\', tty);
923
/* if cnt > 1, output a multi-byte character */
926
head = (head+1) & (N_TTY_BUF_SIZE-1);
927
echo_char_raw(tty->read_buf[head], tty);
928
echo_move_back_col(tty);
930
} else if (kill_type == ERASE && !L_ECHOE(tty)) {
931
echo_char(ERASE_CHAR(tty), tty);
932
} else if (c == '\t') {
933
unsigned int num_chars = 0;
935
unsigned long tail = tty->read_head;
938
* Count the columns used for characters
939
* since the start of input or after a
941
* This info is used to go back the correct
944
while (tail != tty->canon_head) {
945
tail = (tail-1) & (N_TTY_BUF_SIZE-1);
946
c = tty->read_buf[tail];
950
} else if (iscntrl(c)) {
953
} else if (!is_continuation(c, tty)) {
957
echo_erase_tab(num_chars, after_tab, tty);
959
if (iscntrl(c) && L_ECHOCTL(tty)) {
960
echo_char_raw('\b', tty);
961
echo_char_raw(' ', tty);
962
echo_char_raw('\b', tty);
964
if (!iscntrl(c) || L_ECHOCTL(tty)) {
965
echo_char_raw('\b', tty);
966
echo_char_raw(' ', tty);
967
echo_char_raw('\b', tty);
971
if (kill_type == ERASE)
974
if (tty->read_head == tty->canon_head && L_ECHO(tty))
979
* isig - handle the ISIG optio
982
* @flush: force flush
984
* Called when a signal is being sent due to terminal input. This
985
* may caus terminal flushing to take place according to the termios
986
* settings and character used. Called from the driver receive_buf
987
* path so serialized.
989
* Locking: ctrl_lock, read_lock (both via flush buffer)
992
static inline void isig(int sig, struct tty_struct *tty, int flush)
995
kill_pgrp(tty->pgrp, sig, 1);
996
if (flush || !L_NOFLSH(tty)) {
997
n_tty_flush_buffer(tty);
998
tty_driver_flush_buffer(tty);
1003
* n_tty_receive_break - handle break
1006
* An RS232 break event has been hit in the incoming bitstream. This
1007
* can cause a variety of events depending upon the termios settings.
1009
* Called from the receive_buf path so single threaded.
1012
static inline void n_tty_receive_break(struct tty_struct *tty)
1016
if (I_BRKINT(tty)) {
1017
isig(SIGINT, tty, 1);
1020
if (I_PARMRK(tty)) {
1021
put_tty_queue('\377', tty);
1022
put_tty_queue('\0', tty);
1024
put_tty_queue('\0', tty);
1025
wake_up_interruptible(&tty->read_wait);
1029
* n_tty_receive_overrun - handle overrun reporting
1032
* Data arrived faster than we could process it. While the tty
1033
* driver has flagged this the bits that were missed are gone
1036
* Called from the receive_buf path so single threaded. Does not
1037
* need locking as num_overrun and overrun_time are function
1041
static inline void n_tty_receive_overrun(struct tty_struct *tty)
1046
if (time_before(tty->overrun_time, jiffies - HZ) ||
1047
time_after(tty->overrun_time, jiffies)) {
1048
printk(KERN_WARNING "%s: %d input overrun(s)\n",
1051
tty->overrun_time = jiffies;
1052
tty->num_overrun = 0;
1057
* n_tty_receive_parity_error - error notifier
1058
* @tty: terminal device
1061
* Process a parity error and queue the right data to indicate
1062
* the error case if necessary. Locking as per n_tty_receive_buf.
1064
static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1069
if (I_PARMRK(tty)) {
1070
put_tty_queue('\377', tty);
1071
put_tty_queue('\0', tty);
1072
put_tty_queue(c, tty);
1073
} else if (I_INPCK(tty))
1074
put_tty_queue('\0', tty);
1076
put_tty_queue(c, tty);
1077
wake_up_interruptible(&tty->read_wait);
1081
* n_tty_receive_char - perform processing
1082
* @tty: terminal device
1085
* Process an individual character of input received from the driver.
1086
* This is serialized with respect to itself by the rules for the
1090
static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1092
unsigned long flags;
1096
put_tty_queue(c, tty);
1102
if (I_IUCLC(tty) && L_IEXTEN(tty))
1105
if (L_EXTPROC(tty)) {
1106
put_tty_queue(c, tty);
1110
if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1111
I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1112
c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1114
process_echoes(tty);
1119
if (c == START_CHAR(tty)) {
1121
process_echoes(tty);
1122
} else if (c == STOP_CHAR(tty))
1129
* If the previous character was LNEXT, or we know that this
1130
* character is not one of the characters that we'll have to
1131
* handle specially, do shortcut processing to speed things
1134
if (!test_bit(c, tty->process_char_map) || tty->lnext) {
1136
parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1137
if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1138
/* beep if no space */
1140
process_output('\a', tty);
1144
finish_erasing(tty);
1145
/* Record the column of first canon char. */
1146
if (tty->canon_head == tty->read_head)
1147
echo_set_canon_col(tty);
1149
process_echoes(tty);
1152
put_tty_queue(c, tty);
1153
put_tty_queue(c, tty);
1158
if (c == START_CHAR(tty)) {
1160
process_echoes(tty);
1163
if (c == STOP_CHAR(tty)) {
1172
if (c == INTR_CHAR(tty))
1175
if (c == QUIT_CHAR(tty))
1178
if (c == SUSP_CHAR(tty)) {
1181
* Note that we do not use isig() here because we want
1183
* 1) flush, 2) echo, 3) signal
1185
if (!L_NOFLSH(tty)) {
1186
n_tty_flush_buffer(tty);
1187
tty_driver_flush_buffer(tty);
1193
process_echoes(tty);
1196
kill_pgrp(tty->pgrp, signal, 1);
1206
} else if (c == '\n' && I_INLCR(tty))
1210
if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1211
(c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1213
process_echoes(tty);
1216
if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1219
finish_erasing(tty);
1220
if (L_ECHOCTL(tty)) {
1221
echo_char_raw('^', tty);
1222
echo_char_raw('\b', tty);
1223
process_echoes(tty);
1228
if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1230
unsigned long tail = tty->canon_head;
1232
finish_erasing(tty);
1234
echo_char_raw('\n', tty);
1235
while (tail != tty->read_head) {
1236
echo_char(tty->read_buf[tail], tty);
1237
tail = (tail+1) & (N_TTY_BUF_SIZE-1);
1239
process_echoes(tty);
1243
if (tty->read_cnt >= N_TTY_BUF_SIZE) {
1245
process_output('\a', tty);
1248
if (L_ECHO(tty) || L_ECHONL(tty)) {
1249
echo_char_raw('\n', tty);
1250
process_echoes(tty);
1252
goto handle_newline;
1254
if (c == EOF_CHAR(tty)) {
1255
if (tty->read_cnt >= N_TTY_BUF_SIZE)
1257
if (tty->canon_head != tty->read_head)
1258
set_bit(TTY_PUSH, &tty->flags);
1259
c = __DISABLED_CHAR;
1260
goto handle_newline;
1262
if ((c == EOL_CHAR(tty)) ||
1263
(c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1264
parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1266
if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
1268
process_output('\a', tty);
1272
* XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1275
/* Record the column of first canon char. */
1276
if (tty->canon_head == tty->read_head)
1277
echo_set_canon_col(tty);
1279
process_echoes(tty);
1282
* XXX does PARMRK doubling happen for
1283
* EOL_CHAR and EOL2_CHAR?
1286
put_tty_queue(c, tty);
1289
spin_lock_irqsave(&tty->read_lock, flags);
1290
set_bit(tty->read_head, tty->read_flags);
1291
put_tty_queue_nolock(c, tty);
1292
tty->canon_head = tty->read_head;
1294
spin_unlock_irqrestore(&tty->read_lock, flags);
1295
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1296
if (waitqueue_active(&tty->read_wait))
1297
wake_up_interruptible(&tty->read_wait);
1302
parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1303
if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1304
/* beep if no space */
1306
process_output('\a', tty);
1310
finish_erasing(tty);
1312
echo_char_raw('\n', tty);
1314
/* Record the column of first canon char. */
1315
if (tty->canon_head == tty->read_head)
1316
echo_set_canon_col(tty);
1319
process_echoes(tty);
1323
put_tty_queue(c, tty);
1325
put_tty_queue(c, tty);
1330
* n_tty_write_wakeup - asynchronous I/O notifier
1333
* Required for the ptys, serial driver etc. since processes
1334
* that attach themselves to the master and rely on ASYNC
1335
* IO must be woken up
1338
static void n_tty_write_wakeup(struct tty_struct *tty)
1340
if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
1341
kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
1345
* n_tty_receive_buf - data receive
1346
* @tty: terminal device
1349
* @count: characters
1351
* Called by the terminal driver when a block of characters has
1352
* been received. This function must be called from soft contexts
1353
* not from interrupt context. The driver is responsible for making
1354
* calls one at a time and in order (or using flush_to_ldisc)
1357
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1358
char *fp, int count)
1360
const unsigned char *p;
1361
char *f, flags = TTY_NORMAL;
1364
unsigned long cpuflags;
1369
if (tty->real_raw) {
1370
spin_lock_irqsave(&tty->read_lock, cpuflags);
1371
i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1372
N_TTY_BUF_SIZE - tty->read_head);
1374
memcpy(tty->read_buf + tty->read_head, cp, i);
1375
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1380
i = min(N_TTY_BUF_SIZE - tty->read_cnt,
1381
N_TTY_BUF_SIZE - tty->read_head);
1383
memcpy(tty->read_buf + tty->read_head, cp, i);
1384
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
1386
spin_unlock_irqrestore(&tty->read_lock, cpuflags);
1388
for (i = count, p = cp, f = fp; i; i--, p++) {
1393
n_tty_receive_char(tty, *p);
1396
n_tty_receive_break(tty);
1400
n_tty_receive_parity_error(tty, *p);
1403
n_tty_receive_overrun(tty);
1406
printk(KERN_ERR "%s: unknown flag %d\n",
1407
tty_name(tty, buf), flags);
1411
if (tty->ops->flush_chars)
1412
tty->ops->flush_chars(tty);
1415
n_tty_set_room(tty);
1417
if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
1419
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1420
if (waitqueue_active(&tty->read_wait))
1421
wake_up_interruptible(&tty->read_wait);
1425
* Check the remaining room for the input canonicalization
1426
* mode. We don't want to throttle the driver if we're in
1427
* canonical mode and don't have a newline yet!
1429
if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
1433
int is_ignored(int sig)
1435
return (sigismember(¤t->blocked, sig) ||
1436
current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1440
* n_tty_set_termios - termios data changed
1442
* @old: previous data
1444
* Called by the tty layer when the user changes termios flags so
1445
* that the line discipline can plan ahead. This function cannot sleep
1446
* and is protected from re-entry by the tty layer. The user is
1447
* guaranteed that this function will not be re-entered or in progress
1448
* when the ldisc is closed.
1450
* Locking: Caller holds tty->termios_mutex
1453
static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1455
int canon_change = 1;
1459
canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
1461
memset(&tty->read_flags, 0, sizeof tty->read_flags);
1462
tty->canon_head = tty->read_tail;
1463
tty->canon_data = 0;
1467
if (canon_change && !L_ICANON(tty) && tty->read_cnt)
1468
wake_up_interruptible(&tty->read_wait);
1470
tty->icanon = (L_ICANON(tty) != 0);
1471
if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
1474
n_tty_set_room(tty);
1477
if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1478
I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1479
I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1481
memset(tty->process_char_map, 0, 256/8);
1483
if (I_IGNCR(tty) || I_ICRNL(tty))
1484
set_bit('\r', tty->process_char_map);
1486
set_bit('\n', tty->process_char_map);
1488
if (L_ICANON(tty)) {
1489
set_bit(ERASE_CHAR(tty), tty->process_char_map);
1490
set_bit(KILL_CHAR(tty), tty->process_char_map);
1491
set_bit(EOF_CHAR(tty), tty->process_char_map);
1492
set_bit('\n', tty->process_char_map);
1493
set_bit(EOL_CHAR(tty), tty->process_char_map);
1494
if (L_IEXTEN(tty)) {
1495
set_bit(WERASE_CHAR(tty),
1496
tty->process_char_map);
1497
set_bit(LNEXT_CHAR(tty),
1498
tty->process_char_map);
1499
set_bit(EOL2_CHAR(tty),
1500
tty->process_char_map);
1502
set_bit(REPRINT_CHAR(tty),
1503
tty->process_char_map);
1507
set_bit(START_CHAR(tty), tty->process_char_map);
1508
set_bit(STOP_CHAR(tty), tty->process_char_map);
1511
set_bit(INTR_CHAR(tty), tty->process_char_map);
1512
set_bit(QUIT_CHAR(tty), tty->process_char_map);
1513
set_bit(SUSP_CHAR(tty), tty->process_char_map);
1515
clear_bit(__DISABLED_CHAR, tty->process_char_map);
1520
if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1521
(I_IGNPAR(tty) || !I_INPCK(tty)) &&
1522
(tty->driver->flags & TTY_DRIVER_REAL_RAW))
1527
n_tty_set_room(tty);
1528
/* The termios change make the tty ready for I/O */
1529
wake_up_interruptible(&tty->write_wait);
1530
wake_up_interruptible(&tty->read_wait);
1534
* n_tty_close - close the ldisc for this tty
1537
* Called from the terminal layer when this line discipline is
1538
* being shut down, either because of a close or becsuse of a
1539
* discipline change. The function will not be called while other
1540
* ldisc methods are in progress.
1543
static void n_tty_close(struct tty_struct *tty)
1545
n_tty_flush_buffer(tty);
1546
if (tty->read_buf) {
1547
kfree(tty->read_buf);
1548
tty->read_buf = NULL;
1550
if (tty->echo_buf) {
1551
kfree(tty->echo_buf);
1552
tty->echo_buf = NULL;
1557
* n_tty_open - open an ldisc
1558
* @tty: terminal to open
1560
* Called when this line discipline is being attached to the
1561
* terminal device. Can sleep. Called serialized so that no
1562
* other events will occur in parallel. No further open will occur
1566
static int n_tty_open(struct tty_struct *tty)
1571
/* These are ugly. Currently a malloc failure here can panic */
1572
if (!tty->read_buf) {
1573
tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1577
if (!tty->echo_buf) {
1578
tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1583
reset_buffer_flags(tty);
1585
n_tty_set_termios(tty, NULL);
1586
tty->minimum_to_wake = 1;
1591
static inline int input_available_p(struct tty_struct *tty, int amt)
1593
tty_flush_to_ldisc(tty);
1594
if (tty->icanon && !L_EXTPROC(tty)) {
1595
if (tty->canon_data)
1597
} else if (tty->read_cnt >= (amt ? amt : 1))
1604
* copy_from_read_buf - copy read data directly
1605
* @tty: terminal device
1609
* Helper function to speed up n_tty_read. It is only called when
1610
* ICANON is off; it copies characters straight from the tty queue to
1611
* user space directly. It can be profitably called twice; once to
1612
* drain the space from the tail pointer to the (physical) end of the
1613
* buffer, and once to drain the space from the (physical) beginning of
1614
* the buffer to head pointer.
1616
* Called under the tty->atomic_read_lock sem
1620
static int copy_from_read_buf(struct tty_struct *tty,
1621
unsigned char __user **b,
1627
unsigned long flags;
1630
spin_lock_irqsave(&tty->read_lock, flags);
1631
n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail);
1633
spin_unlock_irqrestore(&tty->read_lock, flags);
1635
retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
1637
tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
1638
spin_lock_irqsave(&tty->read_lock, flags);
1639
tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
1641
/* Turn single EOF into zero-length read */
1642
if (L_EXTPROC(tty) && tty->icanon && n == 1) {
1643
if (!tty->read_cnt && (*b)[n-1] == EOF_CHAR(tty))
1646
spin_unlock_irqrestore(&tty->read_lock, flags);
1653
extern ssize_t redirected_tty_write(struct file *, const char __user *,
1657
* job_control - check job control
1659
* @file: file handle
1661
* Perform job control management checks on this file/tty descriptor
1662
* and if appropriate send any needed signals and return a negative
1663
* error code if action should be taken.
1666
* Locking: None - redirected write test is safe, testing
1667
* current->signal should possibly lock current->sighand
1671
static int job_control(struct tty_struct *tty, struct file *file)
1673
/* Job control check -- must be done at start and after
1674
every sleep (POSIX.1 7.1.1.4). */
1675
/* NOTE: not yet done after every sleep pending a thorough
1676
check of the logic of this change. -- jlc */
1677
/* don't stop on /dev/console */
1678
if (file->f_op->write != redirected_tty_write &&
1679
current->signal->tty == tty) {
1681
printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1682
else if (task_pgrp(current) != tty->pgrp) {
1683
if (is_ignored(SIGTTIN) ||
1684
is_current_pgrp_orphaned())
1686
kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1687
set_thread_flag(TIF_SIGPENDING);
1688
return -ERESTARTSYS;
1696
* n_tty_read - read function for tty
1698
* @file: file object
1699
* @buf: userspace buffer pointer
1702
* Perform reads for the line discipline. We are guaranteed that the
1703
* line discipline will not be closed under us but we may get multiple
1704
* parallel readers and must handle this ourselves. We may also get
1705
* a hangup. Always called in user context, may sleep.
1707
* This code must be sure never to sleep through a hangup.
1710
static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1711
unsigned char __user *buf, size_t nr)
1713
unsigned char __user *b = buf;
1714
DECLARE_WAITQUEUE(wait, current);
1720
unsigned long flags;
1725
BUG_ON(!tty->read_buf);
1727
c = job_control(tty, file);
1732
timeout = MAX_SCHEDULE_TIMEOUT;
1734
time = (HZ / 10) * TIME_CHAR(tty);
1735
minimum = MIN_CHAR(tty);
1738
tty->minimum_to_wake = 1;
1739
else if (!waitqueue_active(&tty->read_wait) ||
1740
(tty->minimum_to_wake > minimum))
1741
tty->minimum_to_wake = minimum;
1748
tty->minimum_to_wake = minimum = 1;
1753
* Internal serialization of reads.
1755
if (file->f_flags & O_NONBLOCK) {
1756
if (!mutex_trylock(&tty->atomic_read_lock))
1759
if (mutex_lock_interruptible(&tty->atomic_read_lock))
1760
return -ERESTARTSYS;
1762
packet = tty->packet;
1764
add_wait_queue(&tty->read_wait, &wait);
1766
/* First test for status change. */
1767
if (packet && tty->link->ctrl_status) {
1771
spin_lock_irqsave(&tty->link->ctrl_lock, flags);
1772
cs = tty->link->ctrl_status;
1773
tty->link->ctrl_status = 0;
1774
spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
1775
if (tty_put_user(tty, cs, b++)) {
1783
/* This statement must be first before checking for input
1784
so that any interrupt will set the state back to
1786
set_current_state(TASK_INTERRUPTIBLE);
1788
if (((minimum - (b - buf)) < tty->minimum_to_wake) &&
1789
((minimum - (b - buf)) >= 1))
1790
tty->minimum_to_wake = (minimum - (b - buf));
1792
if (!input_available_p(tty, 0)) {
1793
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
1797
if (tty_hung_up_p(file))
1801
if (file->f_flags & O_NONBLOCK) {
1805
if (signal_pending(current)) {
1806
retval = -ERESTARTSYS;
1809
/* FIXME: does n_tty_set_room need locking ? */
1810
n_tty_set_room(tty);
1811
timeout = schedule_timeout(timeout);
1814
__set_current_state(TASK_RUNNING);
1816
/* Deal with packet mode. */
1817
if (packet && b == buf) {
1818
if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
1826
if (tty->icanon && !L_EXTPROC(tty)) {
1827
/* N.B. avoid overrun if nr == 0 */
1828
while (nr && tty->read_cnt) {
1831
eol = test_and_clear_bit(tty->read_tail,
1833
c = tty->read_buf[tty->read_tail];
1834
spin_lock_irqsave(&tty->read_lock, flags);
1835
tty->read_tail = ((tty->read_tail+1) &
1836
(N_TTY_BUF_SIZE-1));
1839
/* this test should be redundant:
1840
* we shouldn't be reading data if
1843
if (--tty->canon_data < 0)
1844
tty->canon_data = 0;
1846
spin_unlock_irqrestore(&tty->read_lock, flags);
1848
if (!eol || (c != __DISABLED_CHAR)) {
1849
if (tty_put_user(tty, c, b++)) {
1857
tty_audit_push(tty);
1865
/* The copy function takes the read lock and handles
1866
locking internally for this case */
1867
uncopied = copy_from_read_buf(tty, &b, &nr);
1868
uncopied += copy_from_read_buf(tty, &b, &nr);
1875
/* If there is enough space in the read buffer now, let the
1876
* low-level driver know. We use n_tty_chars_in_buffer() to
1877
* check the buffer, as it now knows about canonical mode.
1878
* Otherwise, if the driver is throttled and the line is
1879
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
1880
* we won't get any more characters.
1882
if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
1883
n_tty_set_room(tty);
1884
check_unthrottle(tty);
1887
if (b - buf >= minimum)
1892
mutex_unlock(&tty->atomic_read_lock);
1893
remove_wait_queue(&tty->read_wait, &wait);
1895
if (!waitqueue_active(&tty->read_wait))
1896
tty->minimum_to_wake = minimum;
1898
__set_current_state(TASK_RUNNING);
1903
clear_bit(TTY_PUSH, &tty->flags);
1904
} else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
1907
n_tty_set_room(tty);
1912
* n_tty_write - write function for tty
1914
* @file: file object
1915
* @buf: userspace buffer pointer
1918
* Write function of the terminal device. This is serialized with
1919
* respect to other write callers but not to termios changes, reads
1920
* and other such events. Since the receive code will echo characters,
1921
* thus calling driver write methods, the output_lock is used in
1922
* the output processing functions called here as well as in the
1923
* echo processing function to protect the column state and space
1924
* left in the buffer.
1926
* This code must be sure never to sleep through a hangup.
1928
* Locking: output_lock to protect column state and space left
1929
* (note that the process_output*() functions take this
1933
static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
1934
const unsigned char *buf, size_t nr)
1936
const unsigned char *b = buf;
1937
DECLARE_WAITQUEUE(wait, current);
1941
/* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
1942
if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
1943
retval = tty_check_change(tty);
1948
/* Write out any echoed characters that are still pending */
1949
process_echoes(tty);
1951
add_wait_queue(&tty->write_wait, &wait);
1953
set_current_state(TASK_INTERRUPTIBLE);
1954
if (signal_pending(current)) {
1955
retval = -ERESTARTSYS;
1958
if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
1962
if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) {
1964
ssize_t num = process_output_block(tty, b, nr);
1976
if (process_output(c, tty) < 0)
1980
if (tty->ops->flush_chars)
1981
tty->ops->flush_chars(tty);
1984
c = tty->ops->write(tty, b, nr);
1997
if (file->f_flags & O_NONBLOCK) {
2004
__set_current_state(TASK_RUNNING);
2005
remove_wait_queue(&tty->write_wait, &wait);
2006
if (b - buf != nr && tty->fasync)
2007
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2008
return (b - buf) ? b - buf : retval;
2012
* n_tty_poll - poll method for N_TTY
2013
* @tty: terminal device
2014
* @file: file accessing it
2017
* Called when the line discipline is asked to poll() for data or
2018
* for special events. This code is not serialized with respect to
2019
* other events save open/close.
2021
* This code must be sure never to sleep through a hangup.
2022
* Called without the kernel lock held - fine
2025
static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2028
unsigned int mask = 0;
2030
poll_wait(file, &tty->read_wait, wait);
2031
poll_wait(file, &tty->write_wait, wait);
2032
if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2033
mask |= POLLIN | POLLRDNORM;
2034
if (tty->packet && tty->link->ctrl_status)
2035
mask |= POLLPRI | POLLIN | POLLRDNORM;
2036
if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2038
if (tty_hung_up_p(file))
2040
if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2041
if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2042
tty->minimum_to_wake = MIN_CHAR(tty);
2044
tty->minimum_to_wake = 1;
2046
if (tty->ops->write && !tty_is_writelocked(tty) &&
2047
tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2048
tty_write_room(tty) > 0)
2049
mask |= POLLOUT | POLLWRNORM;
2053
static unsigned long inq_canon(struct tty_struct *tty)
2057
if (!tty->canon_data)
2059
head = tty->canon_head;
2060
tail = tty->read_tail;
2061
nr = (head - tail) & (N_TTY_BUF_SIZE-1);
2062
/* Skip EOF-chars.. */
2063
while (head != tail) {
2064
if (test_bit(tail, tty->read_flags) &&
2065
tty->read_buf[tail] == __DISABLED_CHAR)
2067
tail = (tail+1) & (N_TTY_BUF_SIZE-1);
2072
static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2073
unsigned int cmd, unsigned long arg)
2079
return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2081
/* FIXME: Locking */
2082
retval = tty->read_cnt;
2084
retval = inq_canon(tty);
2085
return put_user(retval, (unsigned int __user *) arg);
2087
return n_tty_ioctl_helper(tty, file, cmd, arg);
2091
struct tty_ldisc_ops tty_ldisc_N_TTY = {
2092
.magic = TTY_LDISC_MAGIC,
2095
.close = n_tty_close,
2096
.flush_buffer = n_tty_flush_buffer,
2097
.chars_in_buffer = n_tty_chars_in_buffer,
2099
.write = n_tty_write,
2100
.ioctl = n_tty_ioctl,
2101
.set_termios = n_tty_set_termios,
2103
.receive_buf = n_tty_receive_buf,
2104
.write_wakeup = n_tty_write_wakeup
2108
* n_tty_inherit_ops - inherit N_TTY methods
2109
* @ops: struct tty_ldisc_ops where to save N_TTY methods
2111
* Used by a generic struct tty_ldisc_ops to easily inherit N_TTY
2115
void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2117
*ops = tty_ldisc_N_TTY;
2119
ops->refcount = ops->flags = 0;
2121
EXPORT_SYMBOL_GPL(n_tty_inherit_ops);
added
removed
drivers/tty/n_tty.c
