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>
52 #include <linux/ratelimit.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
79 # define n_tty_trace(f, args...) trace_printk(f, ##args)
81 # define n_tty_trace(f, args...)
85 /* producer-published */
88 DECLARE_BITMAP(process_char_map, 256);
90 /* private to n_tty_receive_overrun (single-threaded) */
91 unsigned long overrun_time;
97 /* must hold exclusive termios_rwsem to reset these */
98 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
100 /* shared by producer and consumer */
102 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
106 /* consumer-published */
109 /* protected by echo_lock */
110 unsigned char *echo_buf;
111 unsigned int echo_pos;
112 unsigned int echo_cnt;
114 /* protected by output lock */
116 unsigned int canon_column;
118 struct mutex atomic_read_lock;
119 struct mutex output_lock;
120 struct mutex echo_lock;
123 static inline size_t read_cnt(struct n_tty_data *ldata)
125 return ldata->read_head - ldata->read_tail;
128 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
130 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
133 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
135 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
138 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
139 unsigned char __user *ptr)
141 struct n_tty_data *ldata = tty->disc_data;
143 tty_audit_add_data(tty, &x, 1, ldata->icanon);
144 return put_user(x, ptr);
147 static int receive_room(struct tty_struct *tty)
149 struct n_tty_data *ldata = tty->disc_data;
153 /* Multiply read_cnt by 3, since each byte might take up to
154 * three times as many spaces when PARMRK is set (depending on
155 * its flags, e.g. parity error). */
156 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
158 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
161 * If we are doing input canonicalization, and there are no
162 * pending newlines, let characters through without limit, so
163 * that erase characters will be handled. Other excess
164 * characters will be beeped.
167 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
173 * n_tty_set_room - receive space
176 * Re-schedules the flip buffer work if space just became available.
178 * Caller holds exclusive termios_rwsem
180 * n_tty_read()/consumer path:
181 * holds non-exclusive termios_rwsem
184 static void n_tty_set_room(struct tty_struct *tty)
186 struct n_tty_data *ldata = tty->disc_data;
188 /* Did this open up the receive buffer? We may need to flip */
189 if (unlikely(ldata->no_room) && receive_room(tty)) {
192 WARN_RATELIMIT(tty->port->itty == NULL,
193 "scheduling with invalid itty\n");
194 /* see if ldisc has been killed - if so, this means that
195 * even though the ldisc has been halted and ->buf.work
196 * cancelled, ->buf.work is about to be rescheduled
198 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
199 "scheduling buffer work for halted ldisc\n");
200 queue_work(system_unbound_wq, &tty->port->buf.work);
204 static ssize_t chars_in_buffer(struct tty_struct *tty)
206 struct n_tty_data *ldata = tty->disc_data;
212 n = ldata->canon_head - ldata->read_tail;
217 * n_tty_write_wakeup - asynchronous I/O notifier
220 * Required for the ptys, serial driver etc. since processes
221 * that attach themselves to the master and rely on ASYNC
222 * IO must be woken up
225 static void n_tty_write_wakeup(struct tty_struct *tty)
227 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
228 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
231 static inline void n_tty_check_throttle(struct tty_struct *tty)
233 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
236 * Check the remaining room for the input canonicalization
237 * mode. We don't want to throttle the driver if we're in
238 * canonical mode and don't have a newline yet!
242 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
243 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
245 throttled = tty_throttle_safe(tty);
249 __tty_set_flow_change(tty, 0);
252 static inline void n_tty_check_unthrottle(struct tty_struct *tty)
254 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
255 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
256 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
261 n_tty_write_wakeup(tty->link);
262 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
266 /* If there is enough space in the read buffer now, let the
267 * low-level driver know. We use chars_in_buffer() to
268 * check the buffer, as it now knows about canonical mode.
269 * Otherwise, if the driver is throttled and the line is
270 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
271 * we won't get any more characters.
276 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
277 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
282 unthrottled = tty_unthrottle_safe(tty);
286 __tty_set_flow_change(tty, 0);
290 * put_tty_queue - add character to tty
294 * Add a character to the tty read_buf queue.
296 * n_tty_receive_buf()/producer path:
297 * caller holds non-exclusive termios_rwsem
300 * read_head is only considered 'published' if canonical mode is
304 static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
306 if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
307 *read_buf_addr(ldata, ldata->read_head) = c;
313 * reset_buffer_flags - reset buffer state
314 * @tty: terminal to reset
316 * Reset the read buffer counters and clear the flags.
317 * Called from n_tty_open() and n_tty_flush_buffer().
319 * Locking: caller holds exclusive termios_rwsem
320 * (or locking is not required)
323 static void reset_buffer_flags(struct n_tty_data *ldata)
325 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
327 mutex_lock(&ldata->echo_lock);
328 ldata->echo_pos = ldata->echo_cnt = 0;
329 mutex_unlock(&ldata->echo_lock);
332 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
335 static void n_tty_packet_mode_flush(struct tty_struct *tty)
339 spin_lock_irqsave(&tty->ctrl_lock, flags);
340 if (tty->link->packet) {
341 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
342 wake_up_interruptible(&tty->link->read_wait);
344 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
348 * n_tty_flush_buffer - clean input queue
349 * @tty: terminal device
351 * Flush the input buffer. Called when the tty layer wants the
352 * buffer flushed (eg at hangup) or when the N_TTY line discipline
353 * internally has to clean the pending queue (for example some signals).
355 * Holds termios_rwsem to exclude producer/consumer while
356 * buffer indices are reset.
358 * Locking: ctrl_lock, exclusive termios_rwsem
361 static void n_tty_flush_buffer(struct tty_struct *tty)
363 down_write(&tty->termios_rwsem);
364 reset_buffer_flags(tty->disc_data);
368 n_tty_packet_mode_flush(tty);
369 up_write(&tty->termios_rwsem);
373 * n_tty_chars_in_buffer - report available bytes
376 * Report the number of characters buffered to be delivered to user
377 * at this instant in time.
379 * Locking: exclusive termios_rwsem
382 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
386 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
388 down_write(&tty->termios_rwsem);
389 n = chars_in_buffer(tty);
390 up_write(&tty->termios_rwsem);
395 * is_utf8_continuation - utf8 multibyte check
398 * Returns true if the utf8 character 'c' is a multibyte continuation
399 * character. We use this to correctly compute the on screen size
400 * of the character when printing
403 static inline int is_utf8_continuation(unsigned char c)
405 return (c & 0xc0) == 0x80;
409 * is_continuation - multibyte check
412 * Returns true if the utf8 character 'c' is a multibyte continuation
413 * character and the terminal is in unicode mode.
416 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
418 return I_IUTF8(tty) && is_utf8_continuation(c);
422 * do_output_char - output one character
423 * @c: character (or partial unicode symbol)
424 * @tty: terminal device
425 * @space: space available in tty driver write buffer
427 * This is a helper function that handles one output character
428 * (including special characters like TAB, CR, LF, etc.),
429 * doing OPOST processing and putting the results in the
430 * tty driver's write buffer.
432 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
433 * and NLDLY. They simply aren't relevant in the world today.
434 * If you ever need them, add them here.
436 * Returns the number of bytes of buffer space used or -1 if
439 * Locking: should be called under the output_lock to protect
440 * the column state and space left in the buffer
443 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
445 struct n_tty_data *ldata = tty->disc_data;
458 ldata->canon_column = ldata->column = 0;
459 tty->ops->write(tty, "\r\n", 2);
462 ldata->canon_column = ldata->column;
465 if (O_ONOCR(tty) && ldata->column == 0)
470 ldata->canon_column = ldata->column = 0;
473 ldata->canon_column = ldata->column = 0;
476 spaces = 8 - (ldata->column & 7);
477 if (O_TABDLY(tty) == XTABS) {
480 ldata->column += spaces;
481 tty->ops->write(tty, " ", spaces);
484 ldata->column += spaces;
487 if (ldata->column > 0)
494 if (!is_continuation(c, tty))
500 tty_put_char(tty, c);
505 * process_output - output post processor
506 * @c: character (or partial unicode symbol)
507 * @tty: terminal device
509 * Output one character with OPOST processing.
510 * Returns -1 when the output device is full and the character
513 * Locking: output_lock to protect column state and space left
514 * (also, this is called from n_tty_write under the
515 * tty layer write lock)
518 static int process_output(unsigned char c, struct tty_struct *tty)
520 struct n_tty_data *ldata = tty->disc_data;
523 mutex_lock(&ldata->output_lock);
525 space = tty_write_room(tty);
526 retval = do_output_char(c, tty, space);
528 mutex_unlock(&ldata->output_lock);
536 * process_output_block - block post processor
537 * @tty: terminal device
538 * @buf: character buffer
539 * @nr: number of bytes to output
541 * Output a block of characters with OPOST processing.
542 * Returns the number of characters output.
544 * This path is used to speed up block console writes, among other
545 * things when processing blocks of output data. It handles only
546 * the simple cases normally found and helps to generate blocks of
547 * symbols for the console driver and thus improve performance.
549 * Locking: output_lock to protect column state and space left
550 * (also, this is called from n_tty_write under the
551 * tty layer write lock)
554 static ssize_t process_output_block(struct tty_struct *tty,
555 const unsigned char *buf, unsigned int nr)
557 struct n_tty_data *ldata = tty->disc_data;
560 const unsigned char *cp;
562 mutex_lock(&ldata->output_lock);
564 space = tty_write_room(tty);
566 mutex_unlock(&ldata->output_lock);
572 for (i = 0, cp = buf; i < nr; i++, cp++) {
573 unsigned char c = *cp;
581 ldata->canon_column = ldata->column;
584 if (O_ONOCR(tty) && ldata->column == 0)
588 ldata->canon_column = ldata->column = 0;
593 if (ldata->column > 0)
600 if (!is_continuation(c, tty))
607 i = tty->ops->write(tty, buf, i);
609 mutex_unlock(&ldata->output_lock);
614 * process_echoes - write pending echo characters
615 * @tty: terminal device
617 * Write previously buffered echo (and other ldisc-generated)
618 * characters to the tty.
620 * Characters generated by the ldisc (including echoes) need to
621 * be buffered because the driver's write buffer can fill during
622 * heavy program output. Echoing straight to the driver will
623 * often fail under these conditions, causing lost characters and
624 * resulting mismatches of ldisc state information.
626 * Since the ldisc state must represent the characters actually sent
627 * to the driver at the time of the write, operations like certain
628 * changes in column state are also saved in the buffer and executed
631 * A circular fifo buffer is used so that the most recent characters
632 * are prioritized. Also, when control characters are echoed with a
633 * prefixed "^", the pair is treated atomically and thus not separated.
635 * Locking: output_lock to protect column state and space left,
636 * echo_lock to protect the echo buffer
639 static void process_echoes(struct tty_struct *tty)
641 struct n_tty_data *ldata = tty->disc_data;
644 unsigned char *cp, *buf_end;
646 if (!ldata->echo_cnt)
649 mutex_lock(&ldata->output_lock);
650 mutex_lock(&ldata->echo_lock);
652 space = tty_write_room(tty);
654 buf_end = ldata->echo_buf + N_TTY_BUF_SIZE;
655 cp = ldata->echo_buf + ldata->echo_pos;
656 nr = ldata->echo_cnt;
659 if (c == ECHO_OP_START) {
662 int no_space_left = 0;
665 * If the buffer byte is the start of a multi-byte
666 * operation, get the next byte, which is either the
667 * op code or a control character value.
671 opp -= N_TTY_BUF_SIZE;
675 unsigned int num_chars, num_bs;
677 case ECHO_OP_ERASE_TAB:
678 if (++opp == buf_end)
679 opp -= N_TTY_BUF_SIZE;
683 * Determine how many columns to go back
684 * in order to erase the tab.
685 * This depends on the number of columns
686 * used by other characters within the tab
687 * area. If this (modulo 8) count is from
688 * the start of input rather than from a
689 * previous tab, we offset by canon column.
690 * Otherwise, tab spacing is normal.
692 if (!(num_chars & 0x80))
693 num_chars += ldata->canon_column;
694 num_bs = 8 - (num_chars & 7);
696 if (num_bs > space) {
702 tty_put_char(tty, '\b');
703 if (ldata->column > 0)
710 case ECHO_OP_SET_CANON_COL:
711 ldata->canon_column = ldata->column;
716 case ECHO_OP_MOVE_BACK_COL:
717 if (ldata->column > 0)
724 /* This is an escaped echo op start code */
729 tty_put_char(tty, ECHO_OP_START);
738 * If the op is not a special byte code,
739 * it is a ctrl char tagged to be echoed
740 * as "^X" (where X is the letter
741 * representing the control char).
742 * Note that we must ensure there is
743 * enough space for the whole ctrl pair.
750 tty_put_char(tty, '^');
751 tty_put_char(tty, op ^ 0100);
762 int retval = do_output_char(c, tty, space);
769 tty_put_char(tty, c);
776 /* When end of circular buffer reached, wrap around */
778 cp -= N_TTY_BUF_SIZE;
785 int num_processed = ldata->echo_cnt - nr;
786 ldata->echo_pos += num_processed;
787 ldata->echo_pos &= N_TTY_BUF_SIZE - 1;
788 ldata->echo_cnt = nr;
791 mutex_unlock(&ldata->echo_lock);
792 mutex_unlock(&ldata->output_lock);
794 if (tty->ops->flush_chars)
795 tty->ops->flush_chars(tty);
799 * add_echo_byte - add a byte to the echo buffer
800 * @c: unicode byte to echo
803 * Add a character or operation byte to the echo buffer.
805 * Should be called under the echo lock to protect the echo buffer.
808 static void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
812 if (ldata->echo_cnt == N_TTY_BUF_SIZE) {
813 /* Circular buffer is already at capacity */
814 new_byte_pos = ldata->echo_pos;
817 * Since the buffer start position needs to be advanced,
818 * be sure to step by a whole operation byte group.
820 if (ldata->echo_buf[ldata->echo_pos] == ECHO_OP_START) {
821 if (ldata->echo_buf[(ldata->echo_pos + 1) &
822 (N_TTY_BUF_SIZE - 1)] ==
824 ldata->echo_pos += 3;
825 ldata->echo_cnt -= 2;
827 ldata->echo_pos += 2;
828 ldata->echo_cnt -= 1;
833 ldata->echo_pos &= N_TTY_BUF_SIZE - 1;
835 new_byte_pos = ldata->echo_pos + ldata->echo_cnt;
836 new_byte_pos &= N_TTY_BUF_SIZE - 1;
840 ldata->echo_buf[new_byte_pos] = c;
844 * echo_move_back_col - add operation to move back a column
847 * Add an operation to the echo buffer to move back one column.
849 * Locking: echo_lock to protect the echo buffer
852 static void echo_move_back_col(struct n_tty_data *ldata)
854 mutex_lock(&ldata->echo_lock);
855 add_echo_byte(ECHO_OP_START, ldata);
856 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
857 mutex_unlock(&ldata->echo_lock);
861 * echo_set_canon_col - add operation to set the canon column
864 * Add an operation to the echo buffer to set the canon column
865 * to the current column.
867 * Locking: echo_lock to protect the echo buffer
870 static void echo_set_canon_col(struct n_tty_data *ldata)
872 mutex_lock(&ldata->echo_lock);
873 add_echo_byte(ECHO_OP_START, ldata);
874 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
875 mutex_unlock(&ldata->echo_lock);
879 * echo_erase_tab - add operation to erase a tab
880 * @num_chars: number of character columns already used
881 * @after_tab: true if num_chars starts after a previous tab
884 * Add an operation to the echo buffer to erase a tab.
886 * Called by the eraser function, which knows how many character
887 * columns have been used since either a previous tab or the start
888 * of input. This information will be used later, along with
889 * canon column (if applicable), to go back the correct number
892 * Locking: echo_lock to protect the echo buffer
895 static void echo_erase_tab(unsigned int num_chars, int after_tab,
896 struct n_tty_data *ldata)
898 mutex_lock(&ldata->echo_lock);
900 add_echo_byte(ECHO_OP_START, ldata);
901 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
903 /* We only need to know this modulo 8 (tab spacing) */
906 /* Set the high bit as a flag if num_chars is after a previous tab */
910 add_echo_byte(num_chars, ldata);
912 mutex_unlock(&ldata->echo_lock);
916 * echo_char_raw - echo a character raw
917 * @c: unicode byte to echo
918 * @tty: terminal device
920 * Echo user input back onto the screen. This must be called only when
921 * L_ECHO(tty) is true. Called from the driver receive_buf path.
923 * This variant does not treat control characters specially.
925 * Locking: echo_lock to protect the echo buffer
928 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
930 mutex_lock(&ldata->echo_lock);
931 if (c == ECHO_OP_START) {
932 add_echo_byte(ECHO_OP_START, ldata);
933 add_echo_byte(ECHO_OP_START, ldata);
935 add_echo_byte(c, ldata);
937 mutex_unlock(&ldata->echo_lock);
941 * echo_char - echo a character
942 * @c: unicode byte to echo
943 * @tty: terminal device
945 * Echo user input back onto the screen. This must be called only when
946 * L_ECHO(tty) is true. Called from the driver receive_buf path.
948 * This variant tags control characters to be echoed as "^X"
949 * (where X is the letter representing the control char).
951 * Locking: echo_lock to protect the echo buffer
954 static void echo_char(unsigned char c, struct tty_struct *tty)
956 struct n_tty_data *ldata = tty->disc_data;
958 mutex_lock(&ldata->echo_lock);
960 if (c == ECHO_OP_START) {
961 add_echo_byte(ECHO_OP_START, ldata);
962 add_echo_byte(ECHO_OP_START, ldata);
964 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
965 add_echo_byte(ECHO_OP_START, ldata);
966 add_echo_byte(c, ldata);
969 mutex_unlock(&ldata->echo_lock);
973 * finish_erasing - complete erase
977 static inline void finish_erasing(struct n_tty_data *ldata)
979 if (ldata->erasing) {
980 echo_char_raw('/', ldata);
986 * eraser - handle erase function
987 * @c: character input
988 * @tty: terminal device
990 * Perform erase and necessary output when an erase character is
991 * present in the stream from the driver layer. Handles the complexities
992 * of UTF-8 multibyte symbols.
994 * n_tty_receive_buf()/producer path:
995 * caller holds non-exclusive termios_rwsem
998 * Modifying the read_head is not considered a publish in this context
999 * because canonical mode is active -- only canon_head publishes
1002 static void eraser(unsigned char c, struct tty_struct *tty)
1004 struct n_tty_data *ldata = tty->disc_data;
1005 enum { ERASE, WERASE, KILL } kill_type;
1010 if (ldata->read_head == ldata->canon_head) {
1011 /* process_output('\a', tty); */ /* what do you think? */
1014 if (c == ERASE_CHAR(tty))
1016 else if (c == WERASE_CHAR(tty))
1020 ldata->read_head = ldata->canon_head;
1023 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1024 ldata->read_head = ldata->canon_head;
1025 finish_erasing(ldata);
1026 echo_char(KILL_CHAR(tty), tty);
1027 /* Add a newline if ECHOK is on and ECHOKE is off. */
1029 echo_char_raw('\n', ldata);
1036 while (ldata->read_head != ldata->canon_head) {
1037 head = ldata->read_head;
1039 /* erase a single possibly multibyte character */
1042 c = read_buf(ldata, head);
1043 } while (is_continuation(c, tty) && head != ldata->canon_head);
1045 /* do not partially erase */
1046 if (is_continuation(c, tty))
1049 if (kill_type == WERASE) {
1050 /* Equivalent to BSD's ALTWERASE. */
1051 if (isalnum(c) || c == '_')
1053 else if (seen_alnums)
1056 cnt = ldata->read_head - head;
1057 ldata->read_head = head;
1059 if (L_ECHOPRT(tty)) {
1060 if (!ldata->erasing) {
1061 echo_char_raw('\\', ldata);
1064 /* if cnt > 1, output a multi-byte character */
1068 echo_char_raw(read_buf(ldata, head), ldata);
1069 echo_move_back_col(ldata);
1071 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1072 echo_char(ERASE_CHAR(tty), tty);
1073 } else if (c == '\t') {
1074 unsigned int num_chars = 0;
1076 size_t tail = ldata->read_head;
1079 * Count the columns used for characters
1080 * since the start of input or after a
1082 * This info is used to go back the correct
1083 * number of columns.
1085 while (tail != ldata->canon_head) {
1087 c = read_buf(ldata, tail);
1091 } else if (iscntrl(c)) {
1094 } else if (!is_continuation(c, tty)) {
1098 echo_erase_tab(num_chars, after_tab, ldata);
1100 if (iscntrl(c) && L_ECHOCTL(tty)) {
1101 echo_char_raw('\b', ldata);
1102 echo_char_raw(' ', ldata);
1103 echo_char_raw('\b', ldata);
1105 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1106 echo_char_raw('\b', ldata);
1107 echo_char_raw(' ', ldata);
1108 echo_char_raw('\b', ldata);
1112 if (kill_type == ERASE)
1115 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1116 finish_erasing(ldata);
1120 * isig - handle the ISIG optio
1124 * Called when a signal is being sent due to terminal input.
1125 * Called from the driver receive_buf path so serialized.
1127 * Locking: ctrl_lock
1130 static inline void isig(int sig, struct tty_struct *tty)
1132 struct pid *tty_pgrp = tty_get_pgrp(tty);
1134 kill_pgrp(tty_pgrp, sig, 1);
1140 * n_tty_receive_break - handle break
1143 * An RS232 break event has been hit in the incoming bitstream. This
1144 * can cause a variety of events depending upon the termios settings.
1146 * n_tty_receive_buf()/producer path:
1147 * caller holds non-exclusive termios_rwsem
1148 * publishes read_head via put_tty_queue()
1150 * Note: may get exclusive termios_rwsem if flushing input buffer
1153 static inline void n_tty_receive_break(struct tty_struct *tty)
1155 struct n_tty_data *ldata = tty->disc_data;
1159 if (I_BRKINT(tty)) {
1161 if (!L_NOFLSH(tty)) {
1162 /* flushing needs exclusive termios_rwsem */
1163 up_read(&tty->termios_rwsem);
1164 n_tty_flush_buffer(tty);
1165 tty_driver_flush_buffer(tty);
1166 down_read(&tty->termios_rwsem);
1170 if (I_PARMRK(tty)) {
1171 put_tty_queue('\377', ldata);
1172 put_tty_queue('\0', ldata);
1174 put_tty_queue('\0', ldata);
1175 wake_up_interruptible(&tty->read_wait);
1179 * n_tty_receive_overrun - handle overrun reporting
1182 * Data arrived faster than we could process it. While the tty
1183 * driver has flagged this the bits that were missed are gone
1186 * Called from the receive_buf path so single threaded. Does not
1187 * need locking as num_overrun and overrun_time are function
1191 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1193 struct n_tty_data *ldata = tty->disc_data;
1196 ldata->num_overrun++;
1197 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1198 time_after(ldata->overrun_time, jiffies)) {
1199 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1201 ldata->num_overrun);
1202 ldata->overrun_time = jiffies;
1203 ldata->num_overrun = 0;
1208 * n_tty_receive_parity_error - error notifier
1209 * @tty: terminal device
1212 * Process a parity error and queue the right data to indicate
1213 * the error case if necessary.
1215 * n_tty_receive_buf()/producer path:
1216 * caller holds non-exclusive termios_rwsem
1217 * publishes read_head via put_tty_queue()
1219 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1222 struct n_tty_data *ldata = tty->disc_data;
1226 if (I_PARMRK(tty)) {
1227 put_tty_queue('\377', ldata);
1228 put_tty_queue('\0', ldata);
1229 put_tty_queue(c, ldata);
1230 } else if (I_INPCK(tty))
1231 put_tty_queue('\0', ldata);
1233 put_tty_queue(c, ldata);
1234 wake_up_interruptible(&tty->read_wait);
1238 * n_tty_receive_char - perform processing
1239 * @tty: terminal device
1242 * Process an individual character of input received from the driver.
1243 * This is serialized with respect to itself by the rules for the
1246 * n_tty_receive_buf()/producer path:
1247 * caller holds non-exclusive termios_rwsem
1248 * publishes canon_head if canonical mode is active
1249 * otherwise, publishes read_head via put_tty_queue()
1252 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1254 struct n_tty_data *ldata = tty->disc_data;
1258 put_tty_queue(c, ldata);
1264 if (I_IUCLC(tty) && L_IEXTEN(tty))
1267 if (L_EXTPROC(tty)) {
1268 put_tty_queue(c, ldata);
1272 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1273 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1274 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1276 process_echoes(tty);
1281 if (c == START_CHAR(tty)) {
1283 process_echoes(tty);
1284 } else if (c == STOP_CHAR(tty))
1291 * If the previous character was LNEXT, or we know that this
1292 * character is not one of the characters that we'll have to
1293 * handle specially, do shortcut processing to speed things
1296 if (!test_bit(c, ldata->process_char_map) || ldata->lnext) {
1298 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1299 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1300 /* beep if no space */
1302 process_output('\a', tty);
1306 finish_erasing(ldata);
1307 /* Record the column of first canon char. */
1308 if (ldata->canon_head == ldata->read_head)
1309 echo_set_canon_col(ldata);
1311 process_echoes(tty);
1314 put_tty_queue(c, ldata);
1315 put_tty_queue(c, ldata);
1320 if (c == START_CHAR(tty)) {
1322 process_echoes(tty);
1325 if (c == STOP_CHAR(tty)) {
1334 if (c == INTR_CHAR(tty))
1337 if (c == QUIT_CHAR(tty))
1340 if (c == SUSP_CHAR(tty)) {
1342 if (!L_NOFLSH(tty)) {
1343 /* flushing needs exclusive termios_rwsem */
1344 up_read(&tty->termios_rwsem);
1345 n_tty_flush_buffer(tty);
1346 tty_driver_flush_buffer(tty);
1347 down_read(&tty->termios_rwsem);
1353 process_echoes(tty);
1365 } else if (c == '\n' && I_INLCR(tty))
1368 if (ldata->icanon) {
1369 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1370 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1372 process_echoes(tty);
1375 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1378 finish_erasing(ldata);
1379 if (L_ECHOCTL(tty)) {
1380 echo_char_raw('^', ldata);
1381 echo_char_raw('\b', ldata);
1382 process_echoes(tty);
1387 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1389 size_t tail = ldata->canon_head;
1391 finish_erasing(ldata);
1393 echo_char_raw('\n', ldata);
1394 while (tail != ldata->read_head) {
1395 echo_char(read_buf(ldata, tail), tty);
1398 process_echoes(tty);
1402 if (read_cnt(ldata) >= N_TTY_BUF_SIZE) {
1404 process_output('\a', tty);
1407 if (L_ECHO(tty) || L_ECHONL(tty)) {
1408 echo_char_raw('\n', ldata);
1409 process_echoes(tty);
1411 goto handle_newline;
1413 if (c == EOF_CHAR(tty)) {
1414 if (read_cnt(ldata) >= N_TTY_BUF_SIZE)
1416 if (ldata->canon_head != ldata->read_head)
1417 set_bit(TTY_PUSH, &tty->flags);
1418 c = __DISABLED_CHAR;
1419 goto handle_newline;
1421 if ((c == EOL_CHAR(tty)) ||
1422 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1423 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1425 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) {
1427 process_output('\a', tty);
1431 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1434 /* Record the column of first canon char. */
1435 if (ldata->canon_head == ldata->read_head)
1436 echo_set_canon_col(ldata);
1438 process_echoes(tty);
1441 * XXX does PARMRK doubling happen for
1442 * EOL_CHAR and EOL2_CHAR?
1445 put_tty_queue(c, ldata);
1448 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1449 put_tty_queue(c, ldata);
1450 ldata->canon_head = ldata->read_head;
1451 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1452 if (waitqueue_active(&tty->read_wait))
1453 wake_up_interruptible(&tty->read_wait);
1458 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1459 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1460 /* beep if no space */
1462 process_output('\a', tty);
1466 finish_erasing(ldata);
1468 echo_char_raw('\n', ldata);
1470 /* Record the column of first canon char. */
1471 if (ldata->canon_head == ldata->read_head)
1472 echo_set_canon_col(ldata);
1475 process_echoes(tty);
1479 put_tty_queue(c, ldata);
1481 put_tty_queue(c, ldata);
1485 * n_tty_receive_buf - data receive
1486 * @tty: terminal device
1489 * @count: characters
1491 * Called by the terminal driver when a block of characters has
1492 * been received. This function must be called from soft contexts
1493 * not from interrupt context. The driver is responsible for making
1494 * calls one at a time and in order (or using flush_to_ldisc)
1496 * n_tty_receive_buf()/producer path:
1497 * claims non-exclusive termios_rwsem
1498 * publishes read_head and canon_head
1501 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1502 char *fp, int count)
1504 struct n_tty_data *ldata = tty->disc_data;
1505 const unsigned char *p;
1506 char *f, flags = TTY_NORMAL;
1509 if (ldata->real_raw) {
1512 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1513 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1514 n = min_t(size_t, count, n);
1515 memcpy(read_buf_addr(ldata, head), cp, n);
1516 ldata->read_head += n;
1520 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1521 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1522 n = min_t(size_t, count, n);
1523 memcpy(read_buf_addr(ldata, head), cp, n);
1524 ldata->read_head += n;
1528 for (i = count, p = cp, f = fp; i; i--, p++) {
1533 n_tty_receive_char(tty, *p);
1536 n_tty_receive_break(tty);
1540 n_tty_receive_parity_error(tty, *p);
1543 n_tty_receive_overrun(tty);
1546 printk(KERN_ERR "%s: unknown flag %d\n",
1547 tty_name(tty, buf), flags);
1551 if (tty->ops->flush_chars)
1552 tty->ops->flush_chars(tty);
1555 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1557 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1558 if (waitqueue_active(&tty->read_wait))
1559 wake_up_interruptible(&tty->read_wait);
1562 n_tty_check_throttle(tty);
1565 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1566 char *fp, int count)
1568 down_read(&tty->termios_rwsem);
1569 __receive_buf(tty, cp, fp, count);
1570 up_read(&tty->termios_rwsem);
1573 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1574 char *fp, int count)
1576 struct n_tty_data *ldata = tty->disc_data;
1579 down_read(&tty->termios_rwsem);
1581 tty->receive_room = room = receive_room(tty);
1584 count = min(count, room);
1586 __receive_buf(tty, cp, fp, count);
1588 up_read(&tty->termios_rwsem);
1593 int is_ignored(int sig)
1595 return (sigismember(¤t->blocked, sig) ||
1596 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1600 * n_tty_set_termios - termios data changed
1602 * @old: previous data
1604 * Called by the tty layer when the user changes termios flags so
1605 * that the line discipline can plan ahead. This function cannot sleep
1606 * and is protected from re-entry by the tty layer. The user is
1607 * guaranteed that this function will not be re-entered or in progress
1608 * when the ldisc is closed.
1610 * Locking: Caller holds tty->termios_rwsem
1613 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1615 struct n_tty_data *ldata = tty->disc_data;
1616 int canon_change = 1;
1619 canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
1621 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1622 ldata->canon_head = ldata->read_tail;
1627 if (canon_change && !L_ICANON(tty) && read_cnt(ldata))
1628 wake_up_interruptible(&tty->read_wait);
1630 ldata->icanon = (L_ICANON(tty) != 0);
1632 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1633 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1634 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1636 bitmap_zero(ldata->process_char_map, 256);
1638 if (I_IGNCR(tty) || I_ICRNL(tty))
1639 set_bit('\r', ldata->process_char_map);
1641 set_bit('\n', ldata->process_char_map);
1643 if (L_ICANON(tty)) {
1644 set_bit(ERASE_CHAR(tty), ldata->process_char_map);
1645 set_bit(KILL_CHAR(tty), ldata->process_char_map);
1646 set_bit(EOF_CHAR(tty), ldata->process_char_map);
1647 set_bit('\n', ldata->process_char_map);
1648 set_bit(EOL_CHAR(tty), ldata->process_char_map);
1649 if (L_IEXTEN(tty)) {
1650 set_bit(WERASE_CHAR(tty),
1651 ldata->process_char_map);
1652 set_bit(LNEXT_CHAR(tty),
1653 ldata->process_char_map);
1654 set_bit(EOL2_CHAR(tty),
1655 ldata->process_char_map);
1657 set_bit(REPRINT_CHAR(tty),
1658 ldata->process_char_map);
1662 set_bit(START_CHAR(tty), ldata->process_char_map);
1663 set_bit(STOP_CHAR(tty), ldata->process_char_map);
1666 set_bit(INTR_CHAR(tty), ldata->process_char_map);
1667 set_bit(QUIT_CHAR(tty), ldata->process_char_map);
1668 set_bit(SUSP_CHAR(tty), ldata->process_char_map);
1670 clear_bit(__DISABLED_CHAR, ldata->process_char_map);
1672 ldata->real_raw = 0;
1675 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1676 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1677 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1678 ldata->real_raw = 1;
1680 ldata->real_raw = 0;
1682 n_tty_set_room(tty);
1684 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1685 * been stopped by STOP_CHAR(tty) before it.
1687 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1691 /* The termios change make the tty ready for I/O */
1692 wake_up_interruptible(&tty->write_wait);
1693 wake_up_interruptible(&tty->read_wait);
1697 * n_tty_close - close the ldisc for this tty
1700 * Called from the terminal layer when this line discipline is
1701 * being shut down, either because of a close or becsuse of a
1702 * discipline change. The function will not be called while other
1703 * ldisc methods are in progress.
1706 static void n_tty_close(struct tty_struct *tty)
1708 struct n_tty_data *ldata = tty->disc_data;
1711 n_tty_packet_mode_flush(tty);
1713 kfree(ldata->read_buf);
1714 kfree(ldata->echo_buf);
1716 tty->disc_data = NULL;
1720 * n_tty_open - open an ldisc
1721 * @tty: terminal to open
1723 * Called when this line discipline is being attached to the
1724 * terminal device. Can sleep. Called serialized so that no
1725 * other events will occur in parallel. No further open will occur
1729 static int n_tty_open(struct tty_struct *tty)
1731 struct n_tty_data *ldata;
1733 ldata = kzalloc(sizeof(*ldata), GFP_KERNEL);
1737 ldata->overrun_time = jiffies;
1738 mutex_init(&ldata->atomic_read_lock);
1739 mutex_init(&ldata->output_lock);
1740 mutex_init(&ldata->echo_lock);
1742 /* These are ugly. Currently a malloc failure here can panic */
1743 ldata->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1744 ldata->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
1745 if (!ldata->read_buf || !ldata->echo_buf)
1748 tty->disc_data = ldata;
1749 reset_buffer_flags(tty->disc_data);
1751 ldata->minimum_to_wake = 1;
1753 /* indicate buffer work may resume */
1754 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1755 n_tty_set_termios(tty, NULL);
1756 tty_unthrottle(tty);
1760 kfree(ldata->read_buf);
1761 kfree(ldata->echo_buf);
1767 static inline int input_available_p(struct tty_struct *tty, int amt)
1769 struct n_tty_data *ldata = tty->disc_data;
1771 if (ldata->icanon && !L_EXTPROC(tty)) {
1772 if (ldata->canon_head != ldata->read_tail)
1774 } else if (read_cnt(ldata) >= (amt ? amt : 1))
1781 * copy_from_read_buf - copy read data directly
1782 * @tty: terminal device
1786 * Helper function to speed up n_tty_read. It is only called when
1787 * ICANON is off; it copies characters straight from the tty queue to
1788 * user space directly. It can be profitably called twice; once to
1789 * drain the space from the tail pointer to the (physical) end of the
1790 * buffer, and once to drain the space from the (physical) beginning of
1791 * the buffer to head pointer.
1793 * Called under the ldata->atomic_read_lock sem
1795 * n_tty_read()/consumer path:
1796 * caller holds non-exclusive termios_rwsem
1797 * read_tail published
1800 static int copy_from_read_buf(struct tty_struct *tty,
1801 unsigned char __user **b,
1805 struct n_tty_data *ldata = tty->disc_data;
1809 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1812 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1815 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1817 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1818 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1820 ldata->read_tail += n;
1821 /* Turn single EOF into zero-length read */
1822 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1831 * canon_copy_from_read_buf - copy read data in canonical mode
1832 * @tty: terminal device
1836 * Helper function for n_tty_read. It is only called when ICANON is on;
1837 * it copies one line of input up to and including the line-delimiting
1838 * character into the user-space buffer.
1840 * Called under the atomic_read_lock mutex
1842 * n_tty_read()/consumer path:
1843 * caller holds non-exclusive termios_rwsem
1844 * read_tail published
1847 static int canon_copy_from_read_buf(struct tty_struct *tty,
1848 unsigned char __user **b,
1851 struct n_tty_data *ldata = tty->disc_data;
1852 size_t n, size, more, c;
1857 /* N.B. avoid overrun if nr == 0 */
1858 n = min(*nr, read_cnt(ldata));
1862 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1863 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
1865 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1866 __func__, *nr, tail, n, size);
1868 eol = find_next_bit(ldata->read_flags, size, tail);
1869 more = n - (size - tail);
1870 if (eol == N_TTY_BUF_SIZE && more) {
1871 /* scan wrapped without finding set bit */
1872 eol = find_next_bit(ldata->read_flags, more, 0);
1875 } else if (eol != size)
1878 size = N_TTY_BUF_SIZE - tail;
1879 n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
1882 if (found && read_buf(ldata, eol) == __DISABLED_CHAR)
1885 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
1886 __func__, eol, found, n, c, size, more);
1889 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
1892 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
1894 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1902 clear_bit(eol, ldata->read_flags);
1903 smp_mb__after_clear_bit();
1904 ldata->read_tail += c;
1907 tty_audit_push(tty);
1911 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1915 * job_control - check job control
1917 * @file: file handle
1919 * Perform job control management checks on this file/tty descriptor
1920 * and if appropriate send any needed signals and return a negative
1921 * error code if action should be taken.
1923 * Locking: redirected write test is safe
1924 * current->signal->tty check is safe
1925 * ctrl_lock to safely reference tty->pgrp
1928 static int job_control(struct tty_struct *tty, struct file *file)
1930 /* Job control check -- must be done at start and after
1931 every sleep (POSIX.1 7.1.1.4). */
1932 /* NOTE: not yet done after every sleep pending a thorough
1933 check of the logic of this change. -- jlc */
1934 /* don't stop on /dev/console */
1935 if (file->f_op->write == redirected_tty_write ||
1936 current->signal->tty != tty)
1939 spin_lock_irq(&tty->ctrl_lock);
1941 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1942 else if (task_pgrp(current) != tty->pgrp) {
1943 spin_unlock_irq(&tty->ctrl_lock);
1944 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
1946 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1947 set_thread_flag(TIF_SIGPENDING);
1948 return -ERESTARTSYS;
1950 spin_unlock_irq(&tty->ctrl_lock);
1956 * n_tty_read - read function for tty
1958 * @file: file object
1959 * @buf: userspace buffer pointer
1962 * Perform reads for the line discipline. We are guaranteed that the
1963 * line discipline will not be closed under us but we may get multiple
1964 * parallel readers and must handle this ourselves. We may also get
1965 * a hangup. Always called in user context, may sleep.
1967 * This code must be sure never to sleep through a hangup.
1969 * n_tty_read()/consumer path:
1970 * claims non-exclusive termios_rwsem
1971 * publishes read_tail
1974 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
1975 unsigned char __user *buf, size_t nr)
1977 struct n_tty_data *ldata = tty->disc_data;
1978 unsigned char __user *b = buf;
1979 DECLARE_WAITQUEUE(wait, current);
1985 unsigned long flags;
1989 c = job_control(tty, file);
1993 down_read(&tty->termios_rwsem);
1996 timeout = MAX_SCHEDULE_TIMEOUT;
1997 if (!ldata->icanon) {
1998 minimum = MIN_CHAR(tty);
2000 time = (HZ / 10) * TIME_CHAR(tty);
2002 ldata->minimum_to_wake = 1;
2003 else if (!waitqueue_active(&tty->read_wait) ||
2004 (ldata->minimum_to_wake > minimum))
2005 ldata->minimum_to_wake = minimum;
2007 timeout = (HZ / 10) * TIME_CHAR(tty);
2008 ldata->minimum_to_wake = minimum = 1;
2013 * Internal serialization of reads.
2015 if (file->f_flags & O_NONBLOCK) {
2016 if (!mutex_trylock(&ldata->atomic_read_lock)) {
2017 up_read(&tty->termios_rwsem);
2021 if (mutex_lock_interruptible(&ldata->atomic_read_lock)) {
2022 up_read(&tty->termios_rwsem);
2023 return -ERESTARTSYS;
2026 packet = tty->packet;
2028 add_wait_queue(&tty->read_wait, &wait);
2030 /* First test for status change. */
2031 if (packet && tty->link->ctrl_status) {
2035 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
2036 cs = tty->link->ctrl_status;
2037 tty->link->ctrl_status = 0;
2038 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2039 if (tty_put_user(tty, cs, b++)) {
2047 /* This statement must be first before checking for input
2048 so that any interrupt will set the state back to
2050 set_current_state(TASK_INTERRUPTIBLE);
2052 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2053 ((minimum - (b - buf)) >= 1))
2054 ldata->minimum_to_wake = (minimum - (b - buf));
2056 if (!input_available_p(tty, 0)) {
2057 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2061 if (tty_hung_up_p(file))
2065 if (file->f_flags & O_NONBLOCK) {
2069 if (signal_pending(current)) {
2070 retval = -ERESTARTSYS;
2073 n_tty_set_room(tty);
2074 up_read(&tty->termios_rwsem);
2076 timeout = schedule_timeout(timeout);
2078 down_read(&tty->termios_rwsem);
2081 __set_current_state(TASK_RUNNING);
2083 /* Deal with packet mode. */
2084 if (packet && b == buf) {
2085 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2093 if (ldata->icanon && !L_EXTPROC(tty)) {
2094 retval = canon_copy_from_read_buf(tty, &b, &nr);
2099 /* The copy function takes the read lock and handles
2100 locking internally for this case */
2101 uncopied = copy_from_read_buf(tty, &b, &nr);
2102 uncopied += copy_from_read_buf(tty, &b, &nr);
2109 n_tty_check_unthrottle(tty);
2111 if (b - buf >= minimum)
2116 mutex_unlock(&ldata->atomic_read_lock);
2117 remove_wait_queue(&tty->read_wait, &wait);
2119 if (!waitqueue_active(&tty->read_wait))
2120 ldata->minimum_to_wake = minimum;
2122 __set_current_state(TASK_RUNNING);
2127 clear_bit(TTY_PUSH, &tty->flags);
2128 } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) {
2129 up_read(&tty->termios_rwsem);
2133 n_tty_set_room(tty);
2134 up_read(&tty->termios_rwsem);
2139 * n_tty_write - write function for tty
2141 * @file: file object
2142 * @buf: userspace buffer pointer
2145 * Write function of the terminal device. This is serialized with
2146 * respect to other write callers but not to termios changes, reads
2147 * and other such events. Since the receive code will echo characters,
2148 * thus calling driver write methods, the output_lock is used in
2149 * the output processing functions called here as well as in the
2150 * echo processing function to protect the column state and space
2151 * left in the buffer.
2153 * This code must be sure never to sleep through a hangup.
2155 * Locking: output_lock to protect column state and space left
2156 * (note that the process_output*() functions take this
2160 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2161 const unsigned char *buf, size_t nr)
2163 const unsigned char *b = buf;
2164 DECLARE_WAITQUEUE(wait, current);
2168 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2169 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2170 retval = tty_check_change(tty);
2175 down_read(&tty->termios_rwsem);
2177 /* Write out any echoed characters that are still pending */
2178 process_echoes(tty);
2180 add_wait_queue(&tty->write_wait, &wait);
2182 set_current_state(TASK_INTERRUPTIBLE);
2183 if (signal_pending(current)) {
2184 retval = -ERESTARTSYS;
2187 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2193 ssize_t num = process_output_block(tty, b, nr);
2205 if (process_output(c, tty) < 0)
2209 if (tty->ops->flush_chars)
2210 tty->ops->flush_chars(tty);
2213 c = tty->ops->write(tty, b, nr);
2226 if (file->f_flags & O_NONBLOCK) {
2230 up_read(&tty->termios_rwsem);
2234 down_read(&tty->termios_rwsem);
2237 __set_current_state(TASK_RUNNING);
2238 remove_wait_queue(&tty->write_wait, &wait);
2239 if (b - buf != nr && tty->fasync)
2240 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2241 up_read(&tty->termios_rwsem);
2242 return (b - buf) ? b - buf : retval;
2246 * n_tty_poll - poll method for N_TTY
2247 * @tty: terminal device
2248 * @file: file accessing it
2251 * Called when the line discipline is asked to poll() for data or
2252 * for special events. This code is not serialized with respect to
2253 * other events save open/close.
2255 * This code must be sure never to sleep through a hangup.
2256 * Called without the kernel lock held - fine
2259 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2262 struct n_tty_data *ldata = tty->disc_data;
2263 unsigned int mask = 0;
2265 poll_wait(file, &tty->read_wait, wait);
2266 poll_wait(file, &tty->write_wait, wait);
2267 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2268 mask |= POLLIN | POLLRDNORM;
2269 if (tty->packet && tty->link->ctrl_status)
2270 mask |= POLLPRI | POLLIN | POLLRDNORM;
2271 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2273 if (tty_hung_up_p(file))
2275 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2276 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2277 ldata->minimum_to_wake = MIN_CHAR(tty);
2279 ldata->minimum_to_wake = 1;
2281 if (tty->ops->write && !tty_is_writelocked(tty) &&
2282 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2283 tty_write_room(tty) > 0)
2284 mask |= POLLOUT | POLLWRNORM;
2288 static unsigned long inq_canon(struct n_tty_data *ldata)
2290 size_t nr, head, tail;
2292 if (ldata->canon_head == ldata->read_tail)
2294 head = ldata->canon_head;
2295 tail = ldata->read_tail;
2297 /* Skip EOF-chars.. */
2298 while (head != tail) {
2299 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2300 read_buf(ldata, tail) == __DISABLED_CHAR)
2307 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2308 unsigned int cmd, unsigned long arg)
2310 struct n_tty_data *ldata = tty->disc_data;
2315 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2317 down_write(&tty->termios_rwsem);
2319 retval = inq_canon(ldata);
2321 retval = read_cnt(ldata);
2322 up_write(&tty->termios_rwsem);
2323 return put_user(retval, (unsigned int __user *) arg);
2325 return n_tty_ioctl_helper(tty, file, cmd, arg);
2329 static void n_tty_fasync(struct tty_struct *tty, int on)
2331 struct n_tty_data *ldata = tty->disc_data;
2333 if (!waitqueue_active(&tty->read_wait)) {
2335 ldata->minimum_to_wake = 1;
2336 else if (!tty->fasync)
2337 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2341 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2342 .magic = TTY_LDISC_MAGIC,
2345 .close = n_tty_close,
2346 .flush_buffer = n_tty_flush_buffer,
2347 .chars_in_buffer = n_tty_chars_in_buffer,
2349 .write = n_tty_write,
2350 .ioctl = n_tty_ioctl,
2351 .set_termios = n_tty_set_termios,
2353 .receive_buf = n_tty_receive_buf,
2354 .write_wakeup = n_tty_write_wakeup,
2355 .fasync = n_tty_fasync,
2356 .receive_buf2 = n_tty_receive_buf2,
2360 * n_tty_inherit_ops - inherit N_TTY methods
2361 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2363 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2367 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2369 *ops = tty_ldisc_N_TTY;
2371 ops->refcount = ops->flags = 0;
2373 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);