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>
53 #include <linux/vmalloc.h>
56 /* number of characters left in xmit buffer before select has we have room */
57 #define WAKEUP_CHARS 256
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
64 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65 #define TTY_THRESHOLD_UNTHROTTLE 128
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
73 #define ECHO_OP_START 0xff
74 #define ECHO_OP_MOVE_BACK_COL 0x80
75 #define ECHO_OP_SET_CANON_COL 0x81
76 #define ECHO_OP_ERASE_TAB 0x82
78 #define ECHO_COMMIT_WATERMARK 256
79 #define ECHO_BLOCK 256
80 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
85 # define n_tty_trace(f, args...) trace_printk(f, ##args)
87 # define n_tty_trace(f, args...)
91 /* producer-published */
96 DECLARE_BITMAP(char_map, 256);
98 /* private to n_tty_receive_overrun (single-threaded) */
99 unsigned long overrun_time;
105 /* must hold exclusive termios_rwsem to reset these */
106 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
107 unsigned char push:1;
109 /* shared by producer and consumer */
110 char read_buf[N_TTY_BUF_SIZE];
111 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
112 unsigned char echo_buf[N_TTY_BUF_SIZE];
116 /* consumer-published */
120 /* protected by output lock */
122 unsigned int canon_column;
125 struct mutex atomic_read_lock;
126 struct mutex output_lock;
129 static inline size_t read_cnt(struct n_tty_data *ldata)
131 return ldata->read_head - ldata->read_tail;
134 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
136 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
139 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
141 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
144 static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
146 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
149 static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
151 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
154 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
155 unsigned char __user *ptr)
157 struct n_tty_data *ldata = tty->disc_data;
159 tty_audit_add_data(tty, &x, 1, ldata->icanon);
160 return put_user(x, ptr);
163 static int receive_room(struct tty_struct *tty)
165 struct n_tty_data *ldata = tty->disc_data;
169 /* Multiply read_cnt by 3, since each byte might take up to
170 * three times as many spaces when PARMRK is set (depending on
171 * its flags, e.g. parity error). */
172 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
174 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
177 * If we are doing input canonicalization, and there are no
178 * pending newlines, let characters through without limit, so
179 * that erase characters will be handled. Other excess
180 * characters will be beeped.
183 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
189 * n_tty_set_room - receive space
192 * Re-schedules the flip buffer work if space just became available.
194 * Caller holds exclusive termios_rwsem
196 * n_tty_read()/consumer path:
197 * holds non-exclusive termios_rwsem
200 static void n_tty_set_room(struct tty_struct *tty)
202 struct n_tty_data *ldata = tty->disc_data;
204 /* Did this open up the receive buffer? We may need to flip */
205 if (unlikely(ldata->no_room) && receive_room(tty)) {
208 WARN_RATELIMIT(tty->port->itty == NULL,
209 "scheduling with invalid itty\n");
210 /* see if ldisc has been killed - if so, this means that
211 * even though the ldisc has been halted and ->buf.work
212 * cancelled, ->buf.work is about to be rescheduled
214 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
215 "scheduling buffer work for halted ldisc\n");
216 queue_work(system_unbound_wq, &tty->port->buf.work);
220 static ssize_t chars_in_buffer(struct tty_struct *tty)
222 struct n_tty_data *ldata = tty->disc_data;
228 n = ldata->canon_head - ldata->read_tail;
233 * n_tty_write_wakeup - asynchronous I/O notifier
236 * Required for the ptys, serial driver etc. since processes
237 * that attach themselves to the master and rely on ASYNC
238 * IO must be woken up
241 static void n_tty_write_wakeup(struct tty_struct *tty)
243 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
244 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
247 static void n_tty_check_throttle(struct tty_struct *tty)
249 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
252 * Check the remaining room for the input canonicalization
253 * mode. We don't want to throttle the driver if we're in
254 * canonical mode and don't have a newline yet!
258 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
259 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
261 throttled = tty_throttle_safe(tty);
265 __tty_set_flow_change(tty, 0);
268 static void n_tty_check_unthrottle(struct tty_struct *tty)
270 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
271 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
272 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
277 n_tty_write_wakeup(tty->link);
278 if (waitqueue_active(&tty->link->write_wait))
279 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
283 /* If there is enough space in the read buffer now, let the
284 * low-level driver know. We use chars_in_buffer() to
285 * check the buffer, as it now knows about canonical mode.
286 * Otherwise, if the driver is throttled and the line is
287 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
288 * we won't get any more characters.
293 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
294 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
299 unthrottled = tty_unthrottle_safe(tty);
303 __tty_set_flow_change(tty, 0);
307 * put_tty_queue - add character to tty
311 * Add a character to the tty read_buf queue.
313 * n_tty_receive_buf()/producer path:
314 * caller holds non-exclusive termios_rwsem
317 * read_head is only considered 'published' if canonical mode is
321 static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
323 *read_buf_addr(ldata, ldata->read_head++) = c;
327 * reset_buffer_flags - reset buffer state
328 * @tty: terminal to reset
330 * Reset the read buffer counters and clear the flags.
331 * Called from n_tty_open() and n_tty_flush_buffer().
333 * Locking: caller holds exclusive termios_rwsem
334 * (or locking is not required)
337 static void reset_buffer_flags(struct n_tty_data *ldata)
339 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
340 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
341 ldata->line_start = 0;
344 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
348 static void n_tty_packet_mode_flush(struct tty_struct *tty)
352 spin_lock_irqsave(&tty->ctrl_lock, flags);
353 if (tty->link->packet) {
354 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
355 if (waitqueue_active(&tty->link->read_wait))
356 wake_up_interruptible(&tty->link->read_wait);
358 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
362 * n_tty_flush_buffer - clean input queue
363 * @tty: terminal device
365 * Flush the input buffer. Called when the tty layer wants the
366 * buffer flushed (eg at hangup) or when the N_TTY line discipline
367 * internally has to clean the pending queue (for example some signals).
369 * Holds termios_rwsem to exclude producer/consumer while
370 * buffer indices are reset.
372 * Locking: ctrl_lock, exclusive termios_rwsem
375 static void n_tty_flush_buffer(struct tty_struct *tty)
377 down_write(&tty->termios_rwsem);
378 reset_buffer_flags(tty->disc_data);
382 n_tty_packet_mode_flush(tty);
383 up_write(&tty->termios_rwsem);
387 * n_tty_chars_in_buffer - report available bytes
390 * Report the number of characters buffered to be delivered to user
391 * at this instant in time.
393 * Locking: exclusive termios_rwsem
396 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
400 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
402 down_write(&tty->termios_rwsem);
403 n = chars_in_buffer(tty);
404 up_write(&tty->termios_rwsem);
409 * is_utf8_continuation - utf8 multibyte check
412 * Returns true if the utf8 character 'c' is a multibyte continuation
413 * character. We use this to correctly compute the on screen size
414 * of the character when printing
417 static inline int is_utf8_continuation(unsigned char c)
419 return (c & 0xc0) == 0x80;
423 * is_continuation - multibyte check
426 * Returns true if the utf8 character 'c' is a multibyte continuation
427 * character and the terminal is in unicode mode.
430 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
432 return I_IUTF8(tty) && is_utf8_continuation(c);
436 * do_output_char - output one character
437 * @c: character (or partial unicode symbol)
438 * @tty: terminal device
439 * @space: space available in tty driver write buffer
441 * This is a helper function that handles one output character
442 * (including special characters like TAB, CR, LF, etc.),
443 * doing OPOST processing and putting the results in the
444 * tty driver's write buffer.
446 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
447 * and NLDLY. They simply aren't relevant in the world today.
448 * If you ever need them, add them here.
450 * Returns the number of bytes of buffer space used or -1 if
453 * Locking: should be called under the output_lock to protect
454 * the column state and space left in the buffer
457 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
459 struct n_tty_data *ldata = tty->disc_data;
472 ldata->canon_column = ldata->column = 0;
473 tty->ops->write(tty, "\r\n", 2);
476 ldata->canon_column = ldata->column;
479 if (O_ONOCR(tty) && ldata->column == 0)
484 ldata->canon_column = ldata->column = 0;
487 ldata->canon_column = ldata->column = 0;
490 spaces = 8 - (ldata->column & 7);
491 if (O_TABDLY(tty) == XTABS) {
494 ldata->column += spaces;
495 tty->ops->write(tty, " ", spaces);
498 ldata->column += spaces;
501 if (ldata->column > 0)
508 if (!is_continuation(c, tty))
514 tty_put_char(tty, c);
519 * process_output - output post processor
520 * @c: character (or partial unicode symbol)
521 * @tty: terminal device
523 * Output one character with OPOST processing.
524 * Returns -1 when the output device is full and the character
527 * Locking: output_lock to protect column state and space left
528 * (also, this is called from n_tty_write under the
529 * tty layer write lock)
532 static int process_output(unsigned char c, struct tty_struct *tty)
534 struct n_tty_data *ldata = tty->disc_data;
537 mutex_lock(&ldata->output_lock);
539 space = tty_write_room(tty);
540 retval = do_output_char(c, tty, space);
542 mutex_unlock(&ldata->output_lock);
550 * process_output_block - block post processor
551 * @tty: terminal device
552 * @buf: character buffer
553 * @nr: number of bytes to output
555 * Output a block of characters with OPOST processing.
556 * Returns the number of characters output.
558 * This path is used to speed up block console writes, among other
559 * things when processing blocks of output data. It handles only
560 * the simple cases normally found and helps to generate blocks of
561 * symbols for the console driver and thus improve performance.
563 * Locking: output_lock to protect column state and space left
564 * (also, this is called from n_tty_write under the
565 * tty layer write lock)
568 static ssize_t process_output_block(struct tty_struct *tty,
569 const unsigned char *buf, unsigned int nr)
571 struct n_tty_data *ldata = tty->disc_data;
574 const unsigned char *cp;
576 mutex_lock(&ldata->output_lock);
578 space = tty_write_room(tty);
580 mutex_unlock(&ldata->output_lock);
586 for (i = 0, cp = buf; i < nr; i++, cp++) {
587 unsigned char c = *cp;
595 ldata->canon_column = ldata->column;
598 if (O_ONOCR(tty) && ldata->column == 0)
602 ldata->canon_column = ldata->column = 0;
607 if (ldata->column > 0)
614 if (!is_continuation(c, tty))
621 i = tty->ops->write(tty, buf, i);
623 mutex_unlock(&ldata->output_lock);
628 * process_echoes - write pending echo characters
629 * @tty: terminal device
631 * Write previously buffered echo (and other ldisc-generated)
632 * characters to the tty.
634 * Characters generated by the ldisc (including echoes) need to
635 * be buffered because the driver's write buffer can fill during
636 * heavy program output. Echoing straight to the driver will
637 * often fail under these conditions, causing lost characters and
638 * resulting mismatches of ldisc state information.
640 * Since the ldisc state must represent the characters actually sent
641 * to the driver at the time of the write, operations like certain
642 * changes in column state are also saved in the buffer and executed
645 * A circular fifo buffer is used so that the most recent characters
646 * are prioritized. Also, when control characters are echoed with a
647 * prefixed "^", the pair is treated atomically and thus not separated.
649 * Locking: callers must hold output_lock
652 static size_t __process_echoes(struct tty_struct *tty)
654 struct n_tty_data *ldata = tty->disc_data;
655 int space, old_space;
659 old_space = space = tty_write_room(tty);
661 tail = ldata->echo_tail;
662 while (ldata->echo_commit != tail) {
663 c = echo_buf(ldata, tail);
664 if (c == ECHO_OP_START) {
666 int no_space_left = 0;
669 * If the buffer byte is the start of a multi-byte
670 * operation, get the next byte, which is either the
671 * op code or a control character value.
673 op = echo_buf(ldata, tail + 1);
676 unsigned int num_chars, num_bs;
678 case ECHO_OP_ERASE_TAB:
679 num_chars = echo_buf(ldata, tail + 2);
682 * Determine how many columns to go back
683 * in order to erase the tab.
684 * This depends on the number of columns
685 * used by other characters within the tab
686 * area. If this (modulo 8) count is from
687 * the start of input rather than from a
688 * previous tab, we offset by canon column.
689 * Otherwise, tab spacing is normal.
691 if (!(num_chars & 0x80))
692 num_chars += ldata->canon_column;
693 num_bs = 8 - (num_chars & 7);
695 if (num_bs > space) {
701 tty_put_char(tty, '\b');
702 if (ldata->column > 0)
708 case ECHO_OP_SET_CANON_COL:
709 ldata->canon_column = ldata->column;
713 case ECHO_OP_MOVE_BACK_COL:
714 if (ldata->column > 0)
720 /* This is an escaped echo op start code */
725 tty_put_char(tty, ECHO_OP_START);
733 * If the op is not a special byte code,
734 * it is a ctrl char tagged to be echoed
735 * as "^X" (where X is the letter
736 * representing the control char).
737 * Note that we must ensure there is
738 * enough space for the whole ctrl pair.
745 tty_put_char(tty, '^');
746 tty_put_char(tty, op ^ 0100);
756 int retval = do_output_char(c, tty, space);
763 tty_put_char(tty, c);
770 /* If the echo buffer is nearly full (so that the possibility exists
771 * of echo overrun before the next commit), then discard enough
772 * data at the tail to prevent a subsequent overrun */
773 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
774 if (echo_buf(ldata, tail) == ECHO_OP_START) {
775 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
783 ldata->echo_tail = tail;
784 return old_space - space;
787 static void commit_echoes(struct tty_struct *tty)
789 struct n_tty_data *ldata = tty->disc_data;
790 size_t nr, old, echoed;
793 head = ldata->echo_head;
794 old = ldata->echo_commit - ldata->echo_tail;
796 /* Process committed echoes if the accumulated # of bytes
797 * is over the threshold (and try again each time another
798 * block is accumulated) */
799 nr = head - ldata->echo_tail;
800 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
803 mutex_lock(&ldata->output_lock);
804 ldata->echo_commit = head;
805 echoed = __process_echoes(tty);
806 mutex_unlock(&ldata->output_lock);
808 if (echoed && tty->ops->flush_chars)
809 tty->ops->flush_chars(tty);
812 static void process_echoes(struct tty_struct *tty)
814 struct n_tty_data *ldata = tty->disc_data;
817 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
818 ldata->echo_commit == ldata->echo_tail)
821 mutex_lock(&ldata->output_lock);
822 echoed = __process_echoes(tty);
823 mutex_unlock(&ldata->output_lock);
825 if (echoed && tty->ops->flush_chars)
826 tty->ops->flush_chars(tty);
829 static void flush_echoes(struct tty_struct *tty)
831 struct n_tty_data *ldata = tty->disc_data;
833 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
834 ldata->echo_commit == ldata->echo_head)
837 mutex_lock(&ldata->output_lock);
838 ldata->echo_commit = ldata->echo_head;
839 __process_echoes(tty);
840 mutex_unlock(&ldata->output_lock);
844 * add_echo_byte - add a byte to the echo buffer
845 * @c: unicode byte to echo
848 * Add a character or operation byte to the echo buffer.
851 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
853 *echo_buf_addr(ldata, ldata->echo_head++) = c;
857 * echo_move_back_col - add operation to move back a column
860 * Add an operation to the echo buffer to move back one column.
863 static void echo_move_back_col(struct n_tty_data *ldata)
865 add_echo_byte(ECHO_OP_START, ldata);
866 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
870 * echo_set_canon_col - add operation to set the canon column
873 * Add an operation to the echo buffer to set the canon column
874 * to the current column.
877 static void echo_set_canon_col(struct n_tty_data *ldata)
879 add_echo_byte(ECHO_OP_START, ldata);
880 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
884 * echo_erase_tab - add operation to erase a tab
885 * @num_chars: number of character columns already used
886 * @after_tab: true if num_chars starts after a previous tab
889 * Add an operation to the echo buffer to erase a tab.
891 * Called by the eraser function, which knows how many character
892 * columns have been used since either a previous tab or the start
893 * of input. This information will be used later, along with
894 * canon column (if applicable), to go back the correct number
898 static void echo_erase_tab(unsigned int num_chars, int after_tab,
899 struct n_tty_data *ldata)
901 add_echo_byte(ECHO_OP_START, ldata);
902 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
904 /* We only need to know this modulo 8 (tab spacing) */
907 /* Set the high bit as a flag if num_chars is after a previous tab */
911 add_echo_byte(num_chars, ldata);
915 * echo_char_raw - echo a character raw
916 * @c: unicode byte to echo
917 * @tty: terminal device
919 * Echo user input back onto the screen. This must be called only when
920 * L_ECHO(tty) is true. Called from the driver receive_buf path.
922 * This variant does not treat control characters specially.
925 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
927 if (c == ECHO_OP_START) {
928 add_echo_byte(ECHO_OP_START, ldata);
929 add_echo_byte(ECHO_OP_START, ldata);
931 add_echo_byte(c, ldata);
936 * echo_char - echo a character
937 * @c: unicode byte to echo
938 * @tty: terminal device
940 * Echo user input back onto the screen. This must be called only when
941 * L_ECHO(tty) is true. Called from the driver receive_buf path.
943 * This variant tags control characters to be echoed as "^X"
944 * (where X is the letter representing the control char).
947 static void echo_char(unsigned char c, struct tty_struct *tty)
949 struct n_tty_data *ldata = tty->disc_data;
951 if (c == ECHO_OP_START) {
952 add_echo_byte(ECHO_OP_START, ldata);
953 add_echo_byte(ECHO_OP_START, ldata);
955 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
956 add_echo_byte(ECHO_OP_START, ldata);
957 add_echo_byte(c, ldata);
962 * finish_erasing - complete erase
966 static inline void finish_erasing(struct n_tty_data *ldata)
968 if (ldata->erasing) {
969 echo_char_raw('/', ldata);
975 * eraser - handle erase function
976 * @c: character input
977 * @tty: terminal device
979 * Perform erase and necessary output when an erase character is
980 * present in the stream from the driver layer. Handles the complexities
981 * of UTF-8 multibyte symbols.
983 * n_tty_receive_buf()/producer path:
984 * caller holds non-exclusive termios_rwsem
987 * Modifying the read_head is not considered a publish in this context
988 * because canonical mode is active -- only canon_head publishes
991 static void eraser(unsigned char c, struct tty_struct *tty)
993 struct n_tty_data *ldata = tty->disc_data;
994 enum { ERASE, WERASE, KILL } kill_type;
999 if (ldata->read_head == ldata->canon_head) {
1000 /* process_output('\a', tty); */ /* what do you think? */
1003 if (c == ERASE_CHAR(tty))
1005 else if (c == WERASE_CHAR(tty))
1009 ldata->read_head = ldata->canon_head;
1012 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1013 ldata->read_head = ldata->canon_head;
1014 finish_erasing(ldata);
1015 echo_char(KILL_CHAR(tty), tty);
1016 /* Add a newline if ECHOK is on and ECHOKE is off. */
1018 echo_char_raw('\n', ldata);
1025 while (ldata->read_head != ldata->canon_head) {
1026 head = ldata->read_head;
1028 /* erase a single possibly multibyte character */
1031 c = read_buf(ldata, head);
1032 } while (is_continuation(c, tty) && head != ldata->canon_head);
1034 /* do not partially erase */
1035 if (is_continuation(c, tty))
1038 if (kill_type == WERASE) {
1039 /* Equivalent to BSD's ALTWERASE. */
1040 if (isalnum(c) || c == '_')
1042 else if (seen_alnums)
1045 cnt = ldata->read_head - head;
1046 ldata->read_head = head;
1048 if (L_ECHOPRT(tty)) {
1049 if (!ldata->erasing) {
1050 echo_char_raw('\\', ldata);
1053 /* if cnt > 1, output a multi-byte character */
1057 echo_char_raw(read_buf(ldata, head), ldata);
1058 echo_move_back_col(ldata);
1060 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1061 echo_char(ERASE_CHAR(tty), tty);
1062 } else if (c == '\t') {
1063 unsigned int num_chars = 0;
1065 size_t tail = ldata->read_head;
1068 * Count the columns used for characters
1069 * since the start of input or after a
1071 * This info is used to go back the correct
1072 * number of columns.
1074 while (tail != ldata->canon_head) {
1076 c = read_buf(ldata, tail);
1080 } else if (iscntrl(c)) {
1083 } else if (!is_continuation(c, tty)) {
1087 echo_erase_tab(num_chars, after_tab, ldata);
1089 if (iscntrl(c) && L_ECHOCTL(tty)) {
1090 echo_char_raw('\b', ldata);
1091 echo_char_raw(' ', ldata);
1092 echo_char_raw('\b', ldata);
1094 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1095 echo_char_raw('\b', ldata);
1096 echo_char_raw(' ', ldata);
1097 echo_char_raw('\b', ldata);
1101 if (kill_type == ERASE)
1104 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1105 finish_erasing(ldata);
1109 * isig - handle the ISIG optio
1113 * Called when a signal is being sent due to terminal input.
1114 * Called from the driver receive_buf path so serialized.
1116 * Locking: ctrl_lock
1119 static void isig(int sig, struct tty_struct *tty)
1121 struct pid *tty_pgrp = tty_get_pgrp(tty);
1123 kill_pgrp(tty_pgrp, sig, 1);
1129 * n_tty_receive_break - handle break
1132 * An RS232 break event has been hit in the incoming bitstream. This
1133 * can cause a variety of events depending upon the termios settings.
1135 * n_tty_receive_buf()/producer path:
1136 * caller holds non-exclusive termios_rwsem
1137 * publishes read_head via put_tty_queue()
1139 * Note: may get exclusive termios_rwsem if flushing input buffer
1142 static void n_tty_receive_break(struct tty_struct *tty)
1144 struct n_tty_data *ldata = tty->disc_data;
1148 if (I_BRKINT(tty)) {
1150 if (!L_NOFLSH(tty)) {
1151 /* flushing needs exclusive termios_rwsem */
1152 up_read(&tty->termios_rwsem);
1153 n_tty_flush_buffer(tty);
1154 tty_driver_flush_buffer(tty);
1155 down_read(&tty->termios_rwsem);
1159 if (I_PARMRK(tty)) {
1160 put_tty_queue('\377', ldata);
1161 put_tty_queue('\0', ldata);
1163 put_tty_queue('\0', ldata);
1164 if (waitqueue_active(&tty->read_wait))
1165 wake_up_interruptible(&tty->read_wait);
1169 * n_tty_receive_overrun - handle overrun reporting
1172 * Data arrived faster than we could process it. While the tty
1173 * driver has flagged this the bits that were missed are gone
1176 * Called from the receive_buf path so single threaded. Does not
1177 * need locking as num_overrun and overrun_time are function
1181 static void n_tty_receive_overrun(struct tty_struct *tty)
1183 struct n_tty_data *ldata = tty->disc_data;
1186 ldata->num_overrun++;
1187 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1188 time_after(ldata->overrun_time, jiffies)) {
1189 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1191 ldata->num_overrun);
1192 ldata->overrun_time = jiffies;
1193 ldata->num_overrun = 0;
1198 * n_tty_receive_parity_error - error notifier
1199 * @tty: terminal device
1202 * Process a parity error and queue the right data to indicate
1203 * the error case if necessary.
1205 * n_tty_receive_buf()/producer path:
1206 * caller holds non-exclusive termios_rwsem
1207 * publishes read_head via put_tty_queue()
1209 static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1211 struct n_tty_data *ldata = tty->disc_data;
1215 if (I_PARMRK(tty)) {
1216 put_tty_queue('\377', ldata);
1217 put_tty_queue('\0', ldata);
1218 put_tty_queue(c, ldata);
1219 } else if (I_INPCK(tty))
1220 put_tty_queue('\0', ldata);
1222 put_tty_queue(c, ldata);
1223 if (waitqueue_active(&tty->read_wait))
1224 wake_up_interruptible(&tty->read_wait);
1228 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1230 if (!L_NOFLSH(tty)) {
1231 /* flushing needs exclusive termios_rwsem */
1232 up_read(&tty->termios_rwsem);
1233 n_tty_flush_buffer(tty);
1234 tty_driver_flush_buffer(tty);
1235 down_read(&tty->termios_rwsem);
1248 * n_tty_receive_char - perform processing
1249 * @tty: terminal device
1252 * Process an individual character of input received from the driver.
1253 * This is serialized with respect to itself by the rules for the
1256 * n_tty_receive_buf()/producer path:
1257 * caller holds non-exclusive termios_rwsem
1258 * publishes canon_head if canonical mode is active
1259 * otherwise, publishes read_head via put_tty_queue()
1261 * Returns 1 if LNEXT was received, else returns 0
1265 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1267 struct n_tty_data *ldata = tty->disc_data;
1270 if (c == START_CHAR(tty)) {
1275 if (c == STOP_CHAR(tty)) {
1282 if (c == INTR_CHAR(tty)) {
1283 n_tty_receive_signal_char(tty, SIGINT, c);
1285 } else if (c == QUIT_CHAR(tty)) {
1286 n_tty_receive_signal_char(tty, SIGQUIT, c);
1288 } else if (c == SUSP_CHAR(tty)) {
1289 n_tty_receive_signal_char(tty, SIGTSTP, c);
1294 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1296 process_echoes(tty);
1304 } else if (c == '\n' && I_INLCR(tty))
1307 if (ldata->icanon) {
1308 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1309 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1314 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1317 finish_erasing(ldata);
1318 if (L_ECHOCTL(tty)) {
1319 echo_char_raw('^', ldata);
1320 echo_char_raw('\b', ldata);
1326 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1327 size_t tail = ldata->canon_head;
1329 finish_erasing(ldata);
1331 echo_char_raw('\n', ldata);
1332 while (tail != ldata->read_head) {
1333 echo_char(read_buf(ldata, tail), tty);
1340 if (L_ECHO(tty) || L_ECHONL(tty)) {
1341 echo_char_raw('\n', ldata);
1344 goto handle_newline;
1346 if (c == EOF_CHAR(tty)) {
1347 c = __DISABLED_CHAR;
1348 goto handle_newline;
1350 if ((c == EOL_CHAR(tty)) ||
1351 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1353 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1356 /* Record the column of first canon char. */
1357 if (ldata->canon_head == ldata->read_head)
1358 echo_set_canon_col(ldata);
1363 * XXX does PARMRK doubling happen for
1364 * EOL_CHAR and EOL2_CHAR?
1366 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1367 put_tty_queue(c, ldata);
1370 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1371 put_tty_queue(c, ldata);
1372 ldata->canon_head = ldata->read_head;
1373 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1374 if (waitqueue_active(&tty->read_wait))
1375 wake_up_interruptible(&tty->read_wait);
1381 finish_erasing(ldata);
1383 echo_char_raw('\n', ldata);
1385 /* Record the column of first canon char. */
1386 if (ldata->canon_head == ldata->read_head)
1387 echo_set_canon_col(ldata);
1393 /* PARMRK doubling check */
1394 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1395 put_tty_queue(c, ldata);
1397 put_tty_queue(c, ldata);
1402 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1404 struct n_tty_data *ldata = tty->disc_data;
1406 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1408 process_echoes(tty);
1411 finish_erasing(ldata);
1412 /* Record the column of first canon char. */
1413 if (ldata->canon_head == ldata->read_head)
1414 echo_set_canon_col(ldata);
1418 /* PARMRK doubling check */
1419 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1420 put_tty_queue(c, ldata);
1421 put_tty_queue(c, ldata);
1424 static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1426 n_tty_receive_char_inline(tty, c);
1430 n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1432 struct n_tty_data *ldata = tty->disc_data;
1434 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1436 process_echoes(tty);
1439 finish_erasing(ldata);
1440 /* Record the column of first canon char. */
1441 if (ldata->canon_head == ldata->read_head)
1442 echo_set_canon_col(ldata);
1446 put_tty_queue(c, ldata);
1449 static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1453 if (I_IUCLC(tty) && L_IEXTEN(tty))
1457 if (c == STOP_CHAR(tty))
1459 else if (c == START_CHAR(tty) ||
1460 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1461 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1462 c != SUSP_CHAR(tty))) {
1464 process_echoes(tty);
1470 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1476 n_tty_receive_break(tty);
1480 n_tty_receive_parity_error(tty, c);
1483 n_tty_receive_overrun(tty);
1486 printk(KERN_ERR "%s: unknown flag %d\n",
1487 tty_name(tty, buf), flag);
1493 n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1495 struct n_tty_data *ldata = tty->disc_data;
1498 if (likely(flag == TTY_NORMAL)) {
1501 if (I_IUCLC(tty) && L_IEXTEN(tty))
1503 n_tty_receive_char(tty, c);
1505 n_tty_receive_char_flagged(tty, c, flag);
1509 * n_tty_receive_buf - data receive
1510 * @tty: terminal device
1513 * @count: characters
1515 * Called by the terminal driver when a block of characters has
1516 * been received. This function must be called from soft contexts
1517 * not from interrupt context. The driver is responsible for making
1518 * calls one at a time and in order (or using flush_to_ldisc)
1520 * n_tty_receive_buf()/producer path:
1521 * claims non-exclusive termios_rwsem
1522 * publishes read_head and canon_head
1526 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1527 char *fp, int count)
1529 struct n_tty_data *ldata = tty->disc_data;
1532 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1533 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1534 n = min_t(size_t, count, n);
1535 memcpy(read_buf_addr(ldata, head), cp, n);
1536 ldata->read_head += n;
1540 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1541 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1542 n = min_t(size_t, count, n);
1543 memcpy(read_buf_addr(ldata, head), cp, n);
1544 ldata->read_head += n;
1548 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1549 char *fp, int count)
1551 struct n_tty_data *ldata = tty->disc_data;
1552 char flag = TTY_NORMAL;
1557 if (likely(flag == TTY_NORMAL))
1558 put_tty_queue(*cp++, ldata);
1560 n_tty_receive_char_flagged(tty, *cp++, flag);
1565 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1566 char *fp, int count)
1568 char flag = TTY_NORMAL;
1573 if (likely(flag == TTY_NORMAL))
1574 n_tty_receive_char_closing(tty, *cp++);
1576 n_tty_receive_char_flagged(tty, *cp++, flag);
1581 n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1582 char *fp, int count)
1584 struct n_tty_data *ldata = tty->disc_data;
1585 char flag = TTY_NORMAL;
1590 if (likely(flag == TTY_NORMAL)) {
1591 unsigned char c = *cp++;
1595 if (I_IUCLC(tty) && L_IEXTEN(tty))
1597 if (L_EXTPROC(tty)) {
1598 put_tty_queue(c, ldata);
1601 if (!test_bit(c, ldata->char_map))
1602 n_tty_receive_char_inline(tty, c);
1603 else if (n_tty_receive_char_special(tty, c) && count) {
1606 n_tty_receive_char_lnext(tty, *cp++, flag);
1610 n_tty_receive_char_flagged(tty, *cp++, flag);
1615 n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1616 char *fp, int count)
1618 struct n_tty_data *ldata = tty->disc_data;
1619 char flag = TTY_NORMAL;
1624 if (likely(flag == TTY_NORMAL)) {
1625 unsigned char c = *cp++;
1627 if (!test_bit(c, ldata->char_map))
1628 n_tty_receive_char_fast(tty, c);
1629 else if (n_tty_receive_char_special(tty, c) && count) {
1632 n_tty_receive_char_lnext(tty, *cp++, flag);
1636 n_tty_receive_char_flagged(tty, *cp++, flag);
1640 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1641 char *fp, int count)
1643 struct n_tty_data *ldata = tty->disc_data;
1644 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1646 if (ldata->real_raw)
1647 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1648 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1649 n_tty_receive_buf_raw(tty, cp, fp, count);
1650 else if (tty->closing && !L_EXTPROC(tty))
1651 n_tty_receive_buf_closing(tty, cp, fp, count);
1654 char flag = TTY_NORMAL;
1658 n_tty_receive_char_lnext(tty, *cp++, flag);
1662 if (!preops && !I_PARMRK(tty))
1663 n_tty_receive_buf_fast(tty, cp, fp, count);
1665 n_tty_receive_buf_standard(tty, cp, fp, count);
1668 if (tty->ops->flush_chars)
1669 tty->ops->flush_chars(tty);
1672 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1674 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1675 if (waitqueue_active(&tty->read_wait))
1676 wake_up_interruptible(&tty->read_wait);
1681 n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1682 char *fp, int count, int flow)
1684 struct n_tty_data *ldata = tty->disc_data;
1685 int room, n, rcvd = 0;
1687 down_read(&tty->termios_rwsem);
1690 room = receive_room(tty);
1691 n = min(count, room);
1697 __receive_buf(tty, cp, fp, n);
1705 tty->receive_room = room;
1706 n_tty_check_throttle(tty);
1707 up_read(&tty->termios_rwsem);
1712 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1713 char *fp, int count)
1715 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1718 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1719 char *fp, int count)
1721 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1724 int is_ignored(int sig)
1726 return (sigismember(¤t->blocked, sig) ||
1727 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1731 * n_tty_set_termios - termios data changed
1733 * @old: previous data
1735 * Called by the tty layer when the user changes termios flags so
1736 * that the line discipline can plan ahead. This function cannot sleep
1737 * and is protected from re-entry by the tty layer. The user is
1738 * guaranteed that this function will not be re-entered or in progress
1739 * when the ldisc is closed.
1741 * Locking: Caller holds tty->termios_rwsem
1744 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1746 struct n_tty_data *ldata = tty->disc_data;
1748 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1749 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1750 ldata->line_start = ldata->read_tail;
1751 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1752 ldata->canon_head = ldata->read_tail;
1755 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1757 ldata->canon_head = ldata->read_head;
1764 ldata->icanon = (L_ICANON(tty) != 0);
1766 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1767 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1768 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1770 bitmap_zero(ldata->char_map, 256);
1772 if (I_IGNCR(tty) || I_ICRNL(tty))
1773 set_bit('\r', ldata->char_map);
1775 set_bit('\n', ldata->char_map);
1777 if (L_ICANON(tty)) {
1778 set_bit(ERASE_CHAR(tty), ldata->char_map);
1779 set_bit(KILL_CHAR(tty), ldata->char_map);
1780 set_bit(EOF_CHAR(tty), ldata->char_map);
1781 set_bit('\n', ldata->char_map);
1782 set_bit(EOL_CHAR(tty), ldata->char_map);
1783 if (L_IEXTEN(tty)) {
1784 set_bit(WERASE_CHAR(tty), ldata->char_map);
1785 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1786 set_bit(EOL2_CHAR(tty), ldata->char_map);
1788 set_bit(REPRINT_CHAR(tty),
1793 set_bit(START_CHAR(tty), ldata->char_map);
1794 set_bit(STOP_CHAR(tty), ldata->char_map);
1797 set_bit(INTR_CHAR(tty), ldata->char_map);
1798 set_bit(QUIT_CHAR(tty), ldata->char_map);
1799 set_bit(SUSP_CHAR(tty), ldata->char_map);
1801 clear_bit(__DISABLED_CHAR, ldata->char_map);
1803 ldata->real_raw = 0;
1806 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1807 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1808 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1809 ldata->real_raw = 1;
1811 ldata->real_raw = 0;
1813 n_tty_set_room(tty);
1815 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1816 * been stopped by STOP_CHAR(tty) before it.
1818 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped)
1821 /* The termios change make the tty ready for I/O */
1822 if (waitqueue_active(&tty->write_wait))
1823 wake_up_interruptible(&tty->write_wait);
1824 if (waitqueue_active(&tty->read_wait))
1825 wake_up_interruptible(&tty->read_wait);
1829 * n_tty_close - close the ldisc for this tty
1832 * Called from the terminal layer when this line discipline is
1833 * being shut down, either because of a close or becsuse of a
1834 * discipline change. The function will not be called while other
1835 * ldisc methods are in progress.
1838 static void n_tty_close(struct tty_struct *tty)
1840 struct n_tty_data *ldata = tty->disc_data;
1843 n_tty_packet_mode_flush(tty);
1846 tty->disc_data = NULL;
1850 * n_tty_open - open an ldisc
1851 * @tty: terminal to open
1853 * Called when this line discipline is being attached to the
1854 * terminal device. Can sleep. Called serialized so that no
1855 * other events will occur in parallel. No further open will occur
1859 static int n_tty_open(struct tty_struct *tty)
1861 struct n_tty_data *ldata;
1863 /* Currently a malloc failure here can panic */
1864 ldata = vmalloc(sizeof(*ldata));
1868 ldata->overrun_time = jiffies;
1869 mutex_init(&ldata->atomic_read_lock);
1870 mutex_init(&ldata->output_lock);
1872 tty->disc_data = ldata;
1873 reset_buffer_flags(tty->disc_data);
1875 ldata->canon_column = 0;
1876 ldata->minimum_to_wake = 1;
1877 ldata->num_overrun = 0;
1881 /* indicate buffer work may resume */
1882 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1883 n_tty_set_termios(tty, NULL);
1884 tty_unthrottle(tty);
1891 static inline int input_available_p(struct tty_struct *tty, int poll)
1893 struct n_tty_data *ldata = tty->disc_data;
1894 int amt = poll && !TIME_CHAR(tty) ? MIN_CHAR(tty) : 1;
1896 if (ldata->icanon && !L_EXTPROC(tty)) {
1897 if (ldata->canon_head != ldata->read_tail)
1899 } else if (read_cnt(ldata) >= amt)
1906 * copy_from_read_buf - copy read data directly
1907 * @tty: terminal device
1911 * Helper function to speed up n_tty_read. It is only called when
1912 * ICANON is off; it copies characters straight from the tty queue to
1913 * user space directly. It can be profitably called twice; once to
1914 * drain the space from the tail pointer to the (physical) end of the
1915 * buffer, and once to drain the space from the (physical) beginning of
1916 * the buffer to head pointer.
1918 * Called under the ldata->atomic_read_lock sem
1920 * n_tty_read()/consumer path:
1921 * caller holds non-exclusive termios_rwsem
1922 * read_tail published
1925 static int copy_from_read_buf(struct tty_struct *tty,
1926 unsigned char __user **b,
1930 struct n_tty_data *ldata = tty->disc_data;
1934 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1937 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1940 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1942 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1943 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1945 ldata->read_tail += n;
1946 /* Turn single EOF into zero-length read */
1947 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1956 * canon_copy_from_read_buf - copy read data in canonical mode
1957 * @tty: terminal device
1961 * Helper function for n_tty_read. It is only called when ICANON is on;
1962 * it copies one line of input up to and including the line-delimiting
1963 * character into the user-space buffer.
1965 * NB: When termios is changed from non-canonical to canonical mode and
1966 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1967 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1968 * This causes data already processed as input to be immediately available
1969 * as input although a newline has not been received.
1971 * Called under the atomic_read_lock mutex
1973 * n_tty_read()/consumer path:
1974 * caller holds non-exclusive termios_rwsem
1975 * read_tail published
1978 static int canon_copy_from_read_buf(struct tty_struct *tty,
1979 unsigned char __user **b,
1982 struct n_tty_data *ldata = tty->disc_data;
1983 size_t n, size, more, c;
1989 /* N.B. avoid overrun if nr == 0 */
1990 n = min(*nr, read_cnt(ldata));
1994 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1995 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
1997 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1998 __func__, *nr, tail, n, size);
2000 eol = find_next_bit(ldata->read_flags, size, tail);
2001 more = n - (size - tail);
2002 if (eol == N_TTY_BUF_SIZE && more) {
2003 /* scan wrapped without finding set bit */
2004 eol = find_next_bit(ldata->read_flags, more, 0);
2007 } else if (eol != size)
2010 size = N_TTY_BUF_SIZE - tail;
2017 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
2019 eof_push = !n && ldata->read_tail != ldata->line_start;
2022 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2023 __func__, eol, found, n, c, size, more);
2026 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2029 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2031 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2039 clear_bit(eol, ldata->read_flags);
2040 smp_mb__after_clear_bit();
2041 ldata->read_tail += c;
2045 ldata->line_start = ldata->read_tail;
2048 tty_audit_push(tty);
2050 return eof_push ? -EAGAIN : 0;
2053 extern ssize_t redirected_tty_write(struct file *, const char __user *,
2057 * job_control - check job control
2059 * @file: file handle
2061 * Perform job control management checks on this file/tty descriptor
2062 * and if appropriate send any needed signals and return a negative
2063 * error code if action should be taken.
2065 * Locking: redirected write test is safe
2066 * current->signal->tty check is safe
2067 * ctrl_lock to safely reference tty->pgrp
2070 static int job_control(struct tty_struct *tty, struct file *file)
2072 /* Job control check -- must be done at start and after
2073 every sleep (POSIX.1 7.1.1.4). */
2074 /* NOTE: not yet done after every sleep pending a thorough
2075 check of the logic of this change. -- jlc */
2076 /* don't stop on /dev/console */
2077 if (file->f_op->write == redirected_tty_write ||
2078 current->signal->tty != tty)
2081 spin_lock_irq(&tty->ctrl_lock);
2083 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2084 else if (task_pgrp(current) != tty->pgrp) {
2085 spin_unlock_irq(&tty->ctrl_lock);
2086 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2088 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2089 set_thread_flag(TIF_SIGPENDING);
2090 return -ERESTARTSYS;
2092 spin_unlock_irq(&tty->ctrl_lock);
2098 * n_tty_read - read function for tty
2100 * @file: file object
2101 * @buf: userspace buffer pointer
2104 * Perform reads for the line discipline. We are guaranteed that the
2105 * line discipline will not be closed under us but we may get multiple
2106 * parallel readers and must handle this ourselves. We may also get
2107 * a hangup. Always called in user context, may sleep.
2109 * This code must be sure never to sleep through a hangup.
2111 * n_tty_read()/consumer path:
2112 * claims non-exclusive termios_rwsem
2113 * publishes read_tail
2116 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2117 unsigned char __user *buf, size_t nr)
2119 struct n_tty_data *ldata = tty->disc_data;
2120 unsigned char __user *b = buf;
2121 DECLARE_WAITQUEUE(wait, current);
2126 unsigned long flags;
2129 c = job_control(tty, file);
2134 * Internal serialization of reads.
2136 if (file->f_flags & O_NONBLOCK) {
2137 if (!mutex_trylock(&ldata->atomic_read_lock))
2140 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2141 return -ERESTARTSYS;
2144 down_read(&tty->termios_rwsem);
2147 timeout = MAX_SCHEDULE_TIMEOUT;
2148 if (!ldata->icanon) {
2149 minimum = MIN_CHAR(tty);
2151 time = (HZ / 10) * TIME_CHAR(tty);
2153 ldata->minimum_to_wake = 1;
2154 else if (!waitqueue_active(&tty->read_wait) ||
2155 (ldata->minimum_to_wake > minimum))
2156 ldata->minimum_to_wake = minimum;
2158 timeout = (HZ / 10) * TIME_CHAR(tty);
2159 ldata->minimum_to_wake = minimum = 1;
2163 packet = tty->packet;
2165 add_wait_queue(&tty->read_wait, &wait);
2167 /* First test for status change. */
2168 if (packet && tty->link->ctrl_status) {
2172 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
2173 cs = tty->link->ctrl_status;
2174 tty->link->ctrl_status = 0;
2175 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2176 if (tty_put_user(tty, cs, b++)) {
2184 /* This statement must be first before checking for input
2185 so that any interrupt will set the state back to
2187 set_current_state(TASK_INTERRUPTIBLE);
2189 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2190 ((minimum - (b - buf)) >= 1))
2191 ldata->minimum_to_wake = (minimum - (b - buf));
2193 if (!input_available_p(tty, 0)) {
2194 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2195 up_read(&tty->termios_rwsem);
2196 tty_flush_to_ldisc(tty);
2197 down_read(&tty->termios_rwsem);
2198 if (!input_available_p(tty, 0)) {
2203 if (tty_hung_up_p(file))
2207 if (file->f_flags & O_NONBLOCK) {
2211 if (signal_pending(current)) {
2212 retval = -ERESTARTSYS;
2215 n_tty_set_room(tty);
2216 up_read(&tty->termios_rwsem);
2218 timeout = schedule_timeout(timeout);
2220 down_read(&tty->termios_rwsem);
2224 __set_current_state(TASK_RUNNING);
2226 /* Deal with packet mode. */
2227 if (packet && b == buf) {
2228 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2236 if (ldata->icanon && !L_EXTPROC(tty)) {
2237 retval = canon_copy_from_read_buf(tty, &b, &nr);
2238 if (retval == -EAGAIN) {
2245 /* The copy function takes the read lock and handles
2246 locking internally for this case */
2247 uncopied = copy_from_read_buf(tty, &b, &nr);
2248 uncopied += copy_from_read_buf(tty, &b, &nr);
2255 n_tty_check_unthrottle(tty);
2257 if (b - buf >= minimum)
2262 n_tty_set_room(tty);
2263 up_read(&tty->termios_rwsem);
2265 remove_wait_queue(&tty->read_wait, &wait);
2266 if (!waitqueue_active(&tty->read_wait))
2267 ldata->minimum_to_wake = minimum;
2269 mutex_unlock(&ldata->atomic_read_lock);
2271 __set_current_state(TASK_RUNNING);
2279 * n_tty_write - write function for tty
2281 * @file: file object
2282 * @buf: userspace buffer pointer
2285 * Write function of the terminal device. This is serialized with
2286 * respect to other write callers but not to termios changes, reads
2287 * and other such events. Since the receive code will echo characters,
2288 * thus calling driver write methods, the output_lock is used in
2289 * the output processing functions called here as well as in the
2290 * echo processing function to protect the column state and space
2291 * left in the buffer.
2293 * This code must be sure never to sleep through a hangup.
2295 * Locking: output_lock to protect column state and space left
2296 * (note that the process_output*() functions take this
2300 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2301 const unsigned char *buf, size_t nr)
2303 const unsigned char *b = buf;
2304 DECLARE_WAITQUEUE(wait, current);
2308 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2309 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2310 retval = tty_check_change(tty);
2315 down_read(&tty->termios_rwsem);
2317 /* Write out any echoed characters that are still pending */
2318 process_echoes(tty);
2320 add_wait_queue(&tty->write_wait, &wait);
2322 set_current_state(TASK_INTERRUPTIBLE);
2323 if (signal_pending(current)) {
2324 retval = -ERESTARTSYS;
2327 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2333 ssize_t num = process_output_block(tty, b, nr);
2345 if (process_output(c, tty) < 0)
2349 if (tty->ops->flush_chars)
2350 tty->ops->flush_chars(tty);
2353 c = tty->ops->write(tty, b, nr);
2366 if (file->f_flags & O_NONBLOCK) {
2370 up_read(&tty->termios_rwsem);
2374 down_read(&tty->termios_rwsem);
2377 __set_current_state(TASK_RUNNING);
2378 remove_wait_queue(&tty->write_wait, &wait);
2379 if (b - buf != nr && tty->fasync)
2380 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2381 up_read(&tty->termios_rwsem);
2382 return (b - buf) ? b - buf : retval;
2386 * n_tty_poll - poll method for N_TTY
2387 * @tty: terminal device
2388 * @file: file accessing it
2391 * Called when the line discipline is asked to poll() for data or
2392 * for special events. This code is not serialized with respect to
2393 * other events save open/close.
2395 * This code must be sure never to sleep through a hangup.
2396 * Called without the kernel lock held - fine
2399 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2402 struct n_tty_data *ldata = tty->disc_data;
2403 unsigned int mask = 0;
2405 poll_wait(file, &tty->read_wait, wait);
2406 poll_wait(file, &tty->write_wait, wait);
2407 if (input_available_p(tty, 1))
2408 mask |= POLLIN | POLLRDNORM;
2409 if (tty->packet && tty->link->ctrl_status)
2410 mask |= POLLPRI | POLLIN | POLLRDNORM;
2411 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2413 if (tty_hung_up_p(file))
2415 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2416 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2417 ldata->minimum_to_wake = MIN_CHAR(tty);
2419 ldata->minimum_to_wake = 1;
2421 if (tty->ops->write && !tty_is_writelocked(tty) &&
2422 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2423 tty_write_room(tty) > 0)
2424 mask |= POLLOUT | POLLWRNORM;
2428 static unsigned long inq_canon(struct n_tty_data *ldata)
2430 size_t nr, head, tail;
2432 if (ldata->canon_head == ldata->read_tail)
2434 head = ldata->canon_head;
2435 tail = ldata->read_tail;
2437 /* Skip EOF-chars.. */
2438 while (head != tail) {
2439 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2440 read_buf(ldata, tail) == __DISABLED_CHAR)
2447 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2448 unsigned int cmd, unsigned long arg)
2450 struct n_tty_data *ldata = tty->disc_data;
2455 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2457 down_write(&tty->termios_rwsem);
2459 retval = inq_canon(ldata);
2461 retval = read_cnt(ldata);
2462 up_write(&tty->termios_rwsem);
2463 return put_user(retval, (unsigned int __user *) arg);
2465 return n_tty_ioctl_helper(tty, file, cmd, arg);
2469 static void n_tty_fasync(struct tty_struct *tty, int on)
2471 struct n_tty_data *ldata = tty->disc_data;
2473 if (!waitqueue_active(&tty->read_wait)) {
2475 ldata->minimum_to_wake = 1;
2476 else if (!tty->fasync)
2477 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2481 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2482 .magic = TTY_LDISC_MAGIC,
2485 .close = n_tty_close,
2486 .flush_buffer = n_tty_flush_buffer,
2487 .chars_in_buffer = n_tty_chars_in_buffer,
2489 .write = n_tty_write,
2490 .ioctl = n_tty_ioctl,
2491 .set_termios = n_tty_set_termios,
2493 .receive_buf = n_tty_receive_buf,
2494 .write_wakeup = n_tty_write_wakeup,
2495 .fasync = n_tty_fasync,
2496 .receive_buf2 = n_tty_receive_buf2,
2500 * n_tty_inherit_ops - inherit N_TTY methods
2501 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2503 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2507 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2509 *ops = tty_ldisc_N_TTY;
2511 ops->refcount = ops->flags = 0;
2513 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);