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 */
97 DECLARE_BITMAP(char_map, 256);
99 /* private to n_tty_receive_overrun (single-threaded) */
100 unsigned long overrun_time;
106 /* must hold exclusive termios_rwsem to reset these */
107 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
108 unsigned char push:1;
110 /* shared by producer and consumer */
111 char read_buf[N_TTY_BUF_SIZE];
112 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
113 unsigned char echo_buf[N_TTY_BUF_SIZE];
117 /* consumer-published */
121 /* protected by output lock */
123 unsigned int canon_column;
126 struct mutex atomic_read_lock;
127 struct mutex output_lock;
130 static inline size_t read_cnt(struct n_tty_data *ldata)
132 return ldata->read_head - ldata->read_tail;
135 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
137 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
140 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
142 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
145 static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
147 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
150 static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
152 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
155 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
156 unsigned char __user *ptr)
158 struct n_tty_data *ldata = tty->disc_data;
160 tty_audit_add_data(tty, &x, 1, ldata->icanon);
161 return put_user(x, ptr);
164 static int receive_room(struct tty_struct *tty)
166 struct n_tty_data *ldata = tty->disc_data;
170 /* Multiply read_cnt by 3, since each byte might take up to
171 * three times as many spaces when PARMRK is set (depending on
172 * its flags, e.g. parity error). */
173 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
175 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
178 * If we are doing input canonicalization, and there are no
179 * pending newlines, let characters through without limit, so
180 * that erase characters will be handled. Other excess
181 * characters will be beeped.
184 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
190 * n_tty_kick_worker - start input worker (if required)
193 * Re-schedules the flip buffer work if it may have stopped
195 * Caller holds exclusive termios_rwsem
197 * n_tty_read()/consumer path:
198 * holds non-exclusive termios_rwsem
201 static void n_tty_kick_worker(struct tty_struct *tty)
203 struct n_tty_data *ldata = tty->disc_data;
205 /* Did the input worker stop? Restart it */
206 if (unlikely(ldata->no_room)) {
209 WARN_RATELIMIT(tty->port->itty == NULL,
210 "scheduling with invalid itty\n");
211 /* see if ldisc has been killed - if so, this means that
212 * even though the ldisc has been halted and ->buf.work
213 * cancelled, ->buf.work is about to be rescheduled
215 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
216 "scheduling buffer work for halted ldisc\n");
217 queue_work(system_unbound_wq, &tty->port->buf.work);
221 static ssize_t chars_in_buffer(struct tty_struct *tty)
223 struct n_tty_data *ldata = tty->disc_data;
229 n = ldata->canon_head - ldata->read_tail;
234 * n_tty_write_wakeup - asynchronous I/O notifier
237 * Required for the ptys, serial driver etc. since processes
238 * that attach themselves to the master and rely on ASYNC
239 * IO must be woken up
242 static void n_tty_write_wakeup(struct tty_struct *tty)
244 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
245 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
248 static void n_tty_check_throttle(struct tty_struct *tty)
250 struct n_tty_data *ldata = tty->disc_data;
252 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
255 * Check the remaining room for the input canonicalization
256 * mode. We don't want to throttle the driver if we're in
257 * canonical mode and don't have a newline yet!
259 if (ldata->icanon && ldata->canon_head == ldata->read_tail)
264 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
265 if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
267 throttled = tty_throttle_safe(tty);
271 __tty_set_flow_change(tty, 0);
274 static void n_tty_check_unthrottle(struct tty_struct *tty)
276 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
277 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
278 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
282 n_tty_kick_worker(tty);
283 n_tty_write_wakeup(tty->link);
284 if (waitqueue_active(&tty->link->write_wait))
285 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
289 /* If there is enough space in the read buffer now, let the
290 * low-level driver know. We use chars_in_buffer() to
291 * check the buffer, as it now knows about canonical mode.
292 * Otherwise, if the driver is throttled and the line is
293 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
294 * we won't get any more characters.
299 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
300 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
304 n_tty_kick_worker(tty);
305 unthrottled = tty_unthrottle_safe(tty);
309 __tty_set_flow_change(tty, 0);
313 * put_tty_queue - add character to tty
317 * Add a character to the tty read_buf queue.
319 * n_tty_receive_buf()/producer path:
320 * caller holds non-exclusive termios_rwsem
323 * read_head is only considered 'published' if canonical mode is
327 static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
329 *read_buf_addr(ldata, ldata->read_head) = c;
334 * reset_buffer_flags - reset buffer state
335 * @tty: terminal to reset
337 * Reset the read buffer counters and clear the flags.
338 * Called from n_tty_open() and n_tty_flush_buffer().
340 * Locking: caller holds exclusive termios_rwsem
341 * (or locking is not required)
344 static void reset_buffer_flags(struct n_tty_data *ldata)
346 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
347 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
348 ldata->echo_mark = 0;
349 ldata->line_start = 0;
352 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
356 static void n_tty_packet_mode_flush(struct tty_struct *tty)
360 if (tty->link->packet) {
361 spin_lock_irqsave(&tty->ctrl_lock, flags);
362 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
363 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
364 if (waitqueue_active(&tty->link->read_wait))
365 wake_up_interruptible(&tty->link->read_wait);
370 * n_tty_flush_buffer - clean input queue
371 * @tty: terminal device
373 * Flush the input buffer. Called when the tty layer wants the
374 * buffer flushed (eg at hangup) or when the N_TTY line discipline
375 * internally has to clean the pending queue (for example some signals).
377 * Holds termios_rwsem to exclude producer/consumer while
378 * buffer indices are reset.
380 * Locking: ctrl_lock, exclusive termios_rwsem
383 static void n_tty_flush_buffer(struct tty_struct *tty)
385 down_write(&tty->termios_rwsem);
386 reset_buffer_flags(tty->disc_data);
387 n_tty_kick_worker(tty);
390 n_tty_packet_mode_flush(tty);
391 up_write(&tty->termios_rwsem);
395 * n_tty_chars_in_buffer - report available bytes
398 * Report the number of characters buffered to be delivered to user
399 * at this instant in time.
401 * Locking: exclusive termios_rwsem
404 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
408 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
410 down_write(&tty->termios_rwsem);
411 n = chars_in_buffer(tty);
412 up_write(&tty->termios_rwsem);
417 * is_utf8_continuation - utf8 multibyte check
420 * Returns true if the utf8 character 'c' is a multibyte continuation
421 * character. We use this to correctly compute the on screen size
422 * of the character when printing
425 static inline int is_utf8_continuation(unsigned char c)
427 return (c & 0xc0) == 0x80;
431 * is_continuation - multibyte check
434 * Returns true if the utf8 character 'c' is a multibyte continuation
435 * character and the terminal is in unicode mode.
438 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
440 return I_IUTF8(tty) && is_utf8_continuation(c);
444 * do_output_char - output one character
445 * @c: character (or partial unicode symbol)
446 * @tty: terminal device
447 * @space: space available in tty driver write buffer
449 * This is a helper function that handles one output character
450 * (including special characters like TAB, CR, LF, etc.),
451 * doing OPOST processing and putting the results in the
452 * tty driver's write buffer.
454 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
455 * and NLDLY. They simply aren't relevant in the world today.
456 * If you ever need them, add them here.
458 * Returns the number of bytes of buffer space used or -1 if
461 * Locking: should be called under the output_lock to protect
462 * the column state and space left in the buffer
465 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
467 struct n_tty_data *ldata = tty->disc_data;
480 ldata->canon_column = ldata->column = 0;
481 tty->ops->write(tty, "\r\n", 2);
484 ldata->canon_column = ldata->column;
487 if (O_ONOCR(tty) && ldata->column == 0)
492 ldata->canon_column = ldata->column = 0;
495 ldata->canon_column = ldata->column = 0;
498 spaces = 8 - (ldata->column & 7);
499 if (O_TABDLY(tty) == XTABS) {
502 ldata->column += spaces;
503 tty->ops->write(tty, " ", spaces);
506 ldata->column += spaces;
509 if (ldata->column > 0)
516 if (!is_continuation(c, tty))
522 tty_put_char(tty, c);
527 * process_output - output post processor
528 * @c: character (or partial unicode symbol)
529 * @tty: terminal device
531 * Output one character with OPOST processing.
532 * Returns -1 when the output device is full and the character
535 * Locking: output_lock to protect column state and space left
536 * (also, this is called from n_tty_write under the
537 * tty layer write lock)
540 static int process_output(unsigned char c, struct tty_struct *tty)
542 struct n_tty_data *ldata = tty->disc_data;
545 mutex_lock(&ldata->output_lock);
547 space = tty_write_room(tty);
548 retval = do_output_char(c, tty, space);
550 mutex_unlock(&ldata->output_lock);
558 * process_output_block - block post processor
559 * @tty: terminal device
560 * @buf: character buffer
561 * @nr: number of bytes to output
563 * Output a block of characters with OPOST processing.
564 * Returns the number of characters output.
566 * This path is used to speed up block console writes, among other
567 * things when processing blocks of output data. It handles only
568 * the simple cases normally found and helps to generate blocks of
569 * symbols for the console driver and thus improve performance.
571 * Locking: output_lock to protect column state and space left
572 * (also, this is called from n_tty_write under the
573 * tty layer write lock)
576 static ssize_t process_output_block(struct tty_struct *tty,
577 const unsigned char *buf, unsigned int nr)
579 struct n_tty_data *ldata = tty->disc_data;
582 const unsigned char *cp;
584 mutex_lock(&ldata->output_lock);
586 space = tty_write_room(tty);
588 mutex_unlock(&ldata->output_lock);
594 for (i = 0, cp = buf; i < nr; i++, cp++) {
595 unsigned char c = *cp;
603 ldata->canon_column = ldata->column;
606 if (O_ONOCR(tty) && ldata->column == 0)
610 ldata->canon_column = ldata->column = 0;
615 if (ldata->column > 0)
622 if (!is_continuation(c, tty))
629 i = tty->ops->write(tty, buf, i);
631 mutex_unlock(&ldata->output_lock);
636 * process_echoes - write pending echo characters
637 * @tty: terminal device
639 * Write previously buffered echo (and other ldisc-generated)
640 * characters to the tty.
642 * Characters generated by the ldisc (including echoes) need to
643 * be buffered because the driver's write buffer can fill during
644 * heavy program output. Echoing straight to the driver will
645 * often fail under these conditions, causing lost characters and
646 * resulting mismatches of ldisc state information.
648 * Since the ldisc state must represent the characters actually sent
649 * to the driver at the time of the write, operations like certain
650 * changes in column state are also saved in the buffer and executed
653 * A circular fifo buffer is used so that the most recent characters
654 * are prioritized. Also, when control characters are echoed with a
655 * prefixed "^", the pair is treated atomically and thus not separated.
657 * Locking: callers must hold output_lock
660 static size_t __process_echoes(struct tty_struct *tty)
662 struct n_tty_data *ldata = tty->disc_data;
663 int space, old_space;
667 old_space = space = tty_write_room(tty);
669 tail = ldata->echo_tail;
670 while (ldata->echo_commit != tail) {
671 c = echo_buf(ldata, tail);
672 if (c == ECHO_OP_START) {
674 int no_space_left = 0;
677 * If the buffer byte is the start of a multi-byte
678 * operation, get the next byte, which is either the
679 * op code or a control character value.
681 op = echo_buf(ldata, tail + 1);
684 unsigned int num_chars, num_bs;
686 case ECHO_OP_ERASE_TAB:
687 num_chars = echo_buf(ldata, tail + 2);
690 * Determine how many columns to go back
691 * in order to erase the tab.
692 * This depends on the number of columns
693 * used by other characters within the tab
694 * area. If this (modulo 8) count is from
695 * the start of input rather than from a
696 * previous tab, we offset by canon column.
697 * Otherwise, tab spacing is normal.
699 if (!(num_chars & 0x80))
700 num_chars += ldata->canon_column;
701 num_bs = 8 - (num_chars & 7);
703 if (num_bs > space) {
709 tty_put_char(tty, '\b');
710 if (ldata->column > 0)
716 case ECHO_OP_SET_CANON_COL:
717 ldata->canon_column = ldata->column;
721 case ECHO_OP_MOVE_BACK_COL:
722 if (ldata->column > 0)
728 /* This is an escaped echo op start code */
733 tty_put_char(tty, ECHO_OP_START);
741 * If the op is not a special byte code,
742 * it is a ctrl char tagged to be echoed
743 * as "^X" (where X is the letter
744 * representing the control char).
745 * Note that we must ensure there is
746 * enough space for the whole ctrl pair.
753 tty_put_char(tty, '^');
754 tty_put_char(tty, op ^ 0100);
764 int retval = do_output_char(c, tty, space);
771 tty_put_char(tty, c);
778 /* If the echo buffer is nearly full (so that the possibility exists
779 * of echo overrun before the next commit), then discard enough
780 * data at the tail to prevent a subsequent overrun */
781 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
782 if (echo_buf(ldata, tail) == ECHO_OP_START) {
783 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
791 ldata->echo_tail = tail;
792 return old_space - space;
795 static void commit_echoes(struct tty_struct *tty)
797 struct n_tty_data *ldata = tty->disc_data;
798 size_t nr, old, echoed;
801 head = ldata->echo_head;
802 ldata->echo_mark = head;
803 old = ldata->echo_commit - ldata->echo_tail;
805 /* Process committed echoes if the accumulated # of bytes
806 * is over the threshold (and try again each time another
807 * block is accumulated) */
808 nr = head - ldata->echo_tail;
809 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
812 mutex_lock(&ldata->output_lock);
813 ldata->echo_commit = head;
814 echoed = __process_echoes(tty);
815 mutex_unlock(&ldata->output_lock);
817 if (echoed && tty->ops->flush_chars)
818 tty->ops->flush_chars(tty);
821 static void process_echoes(struct tty_struct *tty)
823 struct n_tty_data *ldata = tty->disc_data;
826 if (ldata->echo_mark == ldata->echo_tail)
829 mutex_lock(&ldata->output_lock);
830 ldata->echo_commit = ldata->echo_mark;
831 echoed = __process_echoes(tty);
832 mutex_unlock(&ldata->output_lock);
834 if (echoed && tty->ops->flush_chars)
835 tty->ops->flush_chars(tty);
838 /* NB: echo_mark and echo_head should be equivalent here */
839 static void flush_echoes(struct tty_struct *tty)
841 struct n_tty_data *ldata = tty->disc_data;
843 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
844 ldata->echo_commit == ldata->echo_head)
847 mutex_lock(&ldata->output_lock);
848 ldata->echo_commit = ldata->echo_head;
849 __process_echoes(tty);
850 mutex_unlock(&ldata->output_lock);
854 * add_echo_byte - add a byte to the echo buffer
855 * @c: unicode byte to echo
858 * Add a character or operation byte to the echo buffer.
861 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
863 *echo_buf_addr(ldata, ldata->echo_head++) = c;
867 * echo_move_back_col - add operation to move back a column
870 * Add an operation to the echo buffer to move back one column.
873 static void echo_move_back_col(struct n_tty_data *ldata)
875 add_echo_byte(ECHO_OP_START, ldata);
876 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
880 * echo_set_canon_col - add operation to set the canon column
883 * Add an operation to the echo buffer to set the canon column
884 * to the current column.
887 static void echo_set_canon_col(struct n_tty_data *ldata)
889 add_echo_byte(ECHO_OP_START, ldata);
890 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
894 * echo_erase_tab - add operation to erase a tab
895 * @num_chars: number of character columns already used
896 * @after_tab: true if num_chars starts after a previous tab
899 * Add an operation to the echo buffer to erase a tab.
901 * Called by the eraser function, which knows how many character
902 * columns have been used since either a previous tab or the start
903 * of input. This information will be used later, along with
904 * canon column (if applicable), to go back the correct number
908 static void echo_erase_tab(unsigned int num_chars, int after_tab,
909 struct n_tty_data *ldata)
911 add_echo_byte(ECHO_OP_START, ldata);
912 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
914 /* We only need to know this modulo 8 (tab spacing) */
917 /* Set the high bit as a flag if num_chars is after a previous tab */
921 add_echo_byte(num_chars, ldata);
925 * echo_char_raw - echo a character raw
926 * @c: unicode byte to echo
927 * @tty: terminal device
929 * Echo user input back onto the screen. This must be called only when
930 * L_ECHO(tty) is true. Called from the driver receive_buf path.
932 * This variant does not treat control characters specially.
935 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
937 if (c == ECHO_OP_START) {
938 add_echo_byte(ECHO_OP_START, ldata);
939 add_echo_byte(ECHO_OP_START, ldata);
941 add_echo_byte(c, ldata);
946 * echo_char - echo a character
947 * @c: unicode byte to echo
948 * @tty: terminal device
950 * Echo user input back onto the screen. This must be called only when
951 * L_ECHO(tty) is true. Called from the driver receive_buf path.
953 * This variant tags control characters to be echoed as "^X"
954 * (where X is the letter representing the control char).
957 static void echo_char(unsigned char c, struct tty_struct *tty)
959 struct n_tty_data *ldata = tty->disc_data;
961 if (c == ECHO_OP_START) {
962 add_echo_byte(ECHO_OP_START, ldata);
963 add_echo_byte(ECHO_OP_START, ldata);
965 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
966 add_echo_byte(ECHO_OP_START, ldata);
967 add_echo_byte(c, ldata);
972 * finish_erasing - complete erase
976 static inline void finish_erasing(struct n_tty_data *ldata)
978 if (ldata->erasing) {
979 echo_char_raw('/', ldata);
985 * eraser - handle erase function
986 * @c: character input
987 * @tty: terminal device
989 * Perform erase and necessary output when an erase character is
990 * present in the stream from the driver layer. Handles the complexities
991 * of UTF-8 multibyte symbols.
993 * n_tty_receive_buf()/producer path:
994 * caller holds non-exclusive termios_rwsem
997 * Modifying the read_head is not considered a publish in this context
998 * because canonical mode is active -- only canon_head publishes
1001 static void eraser(unsigned char c, struct tty_struct *tty)
1003 struct n_tty_data *ldata = tty->disc_data;
1004 enum { ERASE, WERASE, KILL } kill_type;
1009 if (ldata->read_head == ldata->canon_head) {
1010 /* process_output('\a', tty); */ /* what do you think? */
1013 if (c == ERASE_CHAR(tty))
1015 else if (c == WERASE_CHAR(tty))
1019 ldata->read_head = ldata->canon_head;
1022 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1023 ldata->read_head = ldata->canon_head;
1024 finish_erasing(ldata);
1025 echo_char(KILL_CHAR(tty), tty);
1026 /* Add a newline if ECHOK is on and ECHOKE is off. */
1028 echo_char_raw('\n', ldata);
1035 while (ldata->read_head != ldata->canon_head) {
1036 head = ldata->read_head;
1038 /* erase a single possibly multibyte character */
1041 c = read_buf(ldata, head);
1042 } while (is_continuation(c, tty) && head != ldata->canon_head);
1044 /* do not partially erase */
1045 if (is_continuation(c, tty))
1048 if (kill_type == WERASE) {
1049 /* Equivalent to BSD's ALTWERASE. */
1050 if (isalnum(c) || c == '_')
1052 else if (seen_alnums)
1055 cnt = ldata->read_head - head;
1056 ldata->read_head = head;
1058 if (L_ECHOPRT(tty)) {
1059 if (!ldata->erasing) {
1060 echo_char_raw('\\', ldata);
1063 /* if cnt > 1, output a multi-byte character */
1067 echo_char_raw(read_buf(ldata, head), ldata);
1068 echo_move_back_col(ldata);
1070 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1071 echo_char(ERASE_CHAR(tty), tty);
1072 } else if (c == '\t') {
1073 unsigned int num_chars = 0;
1075 size_t tail = ldata->read_head;
1078 * Count the columns used for characters
1079 * since the start of input or after a
1081 * This info is used to go back the correct
1082 * number of columns.
1084 while (tail != ldata->canon_head) {
1086 c = read_buf(ldata, tail);
1090 } else if (iscntrl(c)) {
1093 } else if (!is_continuation(c, tty)) {
1097 echo_erase_tab(num_chars, after_tab, ldata);
1099 if (iscntrl(c) && L_ECHOCTL(tty)) {
1100 echo_char_raw('\b', ldata);
1101 echo_char_raw(' ', ldata);
1102 echo_char_raw('\b', ldata);
1104 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1105 echo_char_raw('\b', ldata);
1106 echo_char_raw(' ', ldata);
1107 echo_char_raw('\b', ldata);
1111 if (kill_type == ERASE)
1114 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1115 finish_erasing(ldata);
1119 * isig - handle the ISIG optio
1123 * Called when a signal is being sent due to terminal input.
1124 * Called from the driver receive_buf path so serialized.
1126 * Locking: ctrl_lock
1129 static void isig(int sig, struct tty_struct *tty)
1131 struct pid *tty_pgrp = tty_get_pgrp(tty);
1133 kill_pgrp(tty_pgrp, sig, 1);
1139 * n_tty_receive_break - handle break
1142 * An RS232 break event has been hit in the incoming bitstream. This
1143 * can cause a variety of events depending upon the termios settings.
1145 * n_tty_receive_buf()/producer path:
1146 * caller holds non-exclusive termios_rwsem
1147 * publishes read_head via put_tty_queue()
1149 * Note: may get exclusive termios_rwsem if flushing input buffer
1152 static void n_tty_receive_break(struct tty_struct *tty)
1154 struct n_tty_data *ldata = tty->disc_data;
1158 if (I_BRKINT(tty)) {
1160 if (!L_NOFLSH(tty)) {
1161 /* flushing needs exclusive termios_rwsem */
1162 up_read(&tty->termios_rwsem);
1163 n_tty_flush_buffer(tty);
1164 tty_driver_flush_buffer(tty);
1165 down_read(&tty->termios_rwsem);
1169 if (I_PARMRK(tty)) {
1170 put_tty_queue('\377', ldata);
1171 put_tty_queue('\0', ldata);
1173 put_tty_queue('\0', ldata);
1174 if (waitqueue_active(&tty->read_wait))
1175 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
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 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 void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1221 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);
1231 put_tty_queue('\0', ldata);
1233 put_tty_queue(c, ldata);
1234 if (waitqueue_active(&tty->read_wait))
1235 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1239 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1241 if (!L_NOFLSH(tty)) {
1242 /* flushing needs exclusive termios_rwsem */
1243 up_read(&tty->termios_rwsem);
1244 n_tty_flush_buffer(tty);
1245 tty_driver_flush_buffer(tty);
1246 down_read(&tty->termios_rwsem);
1254 process_echoes(tty);
1260 * n_tty_receive_char - perform processing
1261 * @tty: terminal device
1264 * Process an individual character of input received from the driver.
1265 * This is serialized with respect to itself by the rules for the
1268 * n_tty_receive_buf()/producer path:
1269 * caller holds non-exclusive termios_rwsem
1270 * publishes canon_head if canonical mode is active
1271 * otherwise, publishes read_head via put_tty_queue()
1273 * Returns 1 if LNEXT was received, else returns 0
1277 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1279 struct n_tty_data *ldata = tty->disc_data;
1282 if (c == START_CHAR(tty)) {
1284 process_echoes(tty);
1287 if (c == STOP_CHAR(tty)) {
1294 if (c == INTR_CHAR(tty)) {
1295 n_tty_receive_signal_char(tty, SIGINT, c);
1297 } else if (c == QUIT_CHAR(tty)) {
1298 n_tty_receive_signal_char(tty, SIGQUIT, c);
1300 } else if (c == SUSP_CHAR(tty)) {
1301 n_tty_receive_signal_char(tty, SIGTSTP, c);
1306 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1308 process_echoes(tty);
1316 } else if (c == '\n' && I_INLCR(tty))
1319 if (ldata->icanon) {
1320 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1321 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1326 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1329 finish_erasing(ldata);
1330 if (L_ECHOCTL(tty)) {
1331 echo_char_raw('^', ldata);
1332 echo_char_raw('\b', ldata);
1338 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1339 size_t tail = ldata->canon_head;
1341 finish_erasing(ldata);
1343 echo_char_raw('\n', ldata);
1344 while (tail != ldata->read_head) {
1345 echo_char(read_buf(ldata, tail), tty);
1352 if (L_ECHO(tty) || L_ECHONL(tty)) {
1353 echo_char_raw('\n', ldata);
1356 goto handle_newline;
1358 if (c == EOF_CHAR(tty)) {
1359 c = __DISABLED_CHAR;
1360 goto handle_newline;
1362 if ((c == EOL_CHAR(tty)) ||
1363 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1365 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1368 /* Record the column of first canon char. */
1369 if (ldata->canon_head == ldata->read_head)
1370 echo_set_canon_col(ldata);
1375 * XXX does PARMRK doubling happen for
1376 * EOL_CHAR and EOL2_CHAR?
1378 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1379 put_tty_queue(c, ldata);
1382 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1383 put_tty_queue(c, ldata);
1384 ldata->canon_head = ldata->read_head;
1385 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1386 if (waitqueue_active(&tty->read_wait))
1387 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1393 finish_erasing(ldata);
1395 echo_char_raw('\n', ldata);
1397 /* Record the column of first canon char. */
1398 if (ldata->canon_head == ldata->read_head)
1399 echo_set_canon_col(ldata);
1405 /* PARMRK doubling check */
1406 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1407 put_tty_queue(c, ldata);
1409 put_tty_queue(c, ldata);
1414 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1416 struct n_tty_data *ldata = tty->disc_data;
1418 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1420 process_echoes(tty);
1423 finish_erasing(ldata);
1424 /* Record the column of first canon char. */
1425 if (ldata->canon_head == ldata->read_head)
1426 echo_set_canon_col(ldata);
1430 /* PARMRK doubling check */
1431 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1432 put_tty_queue(c, ldata);
1433 put_tty_queue(c, ldata);
1436 static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1438 n_tty_receive_char_inline(tty, c);
1442 n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1444 struct n_tty_data *ldata = tty->disc_data;
1446 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1448 process_echoes(tty);
1451 finish_erasing(ldata);
1452 /* Record the column of first canon char. */
1453 if (ldata->canon_head == ldata->read_head)
1454 echo_set_canon_col(ldata);
1458 put_tty_queue(c, ldata);
1461 static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1465 if (I_IUCLC(tty) && L_IEXTEN(tty))
1469 if (c == STOP_CHAR(tty))
1471 else if (c == START_CHAR(tty) ||
1472 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1473 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1474 c != SUSP_CHAR(tty))) {
1476 process_echoes(tty);
1482 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1488 n_tty_receive_break(tty);
1492 n_tty_receive_parity_error(tty, c);
1495 n_tty_receive_overrun(tty);
1498 printk(KERN_ERR "%s: unknown flag %d\n",
1499 tty_name(tty, buf), flag);
1505 n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1507 struct n_tty_data *ldata = tty->disc_data;
1510 if (likely(flag == TTY_NORMAL)) {
1513 if (I_IUCLC(tty) && L_IEXTEN(tty))
1515 n_tty_receive_char(tty, c);
1517 n_tty_receive_char_flagged(tty, c, flag);
1521 * n_tty_receive_buf - data receive
1522 * @tty: terminal device
1525 * @count: characters
1527 * Called by the terminal driver when a block of characters has
1528 * been received. This function must be called from soft contexts
1529 * not from interrupt context. The driver is responsible for making
1530 * calls one at a time and in order (or using flush_to_ldisc)
1532 * n_tty_receive_buf()/producer path:
1533 * claims non-exclusive termios_rwsem
1534 * publishes read_head and canon_head
1538 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1539 char *fp, int count)
1541 struct n_tty_data *ldata = tty->disc_data;
1544 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1545 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1546 n = min_t(size_t, count, n);
1547 memcpy(read_buf_addr(ldata, head), cp, n);
1548 ldata->read_head += n;
1552 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1553 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1554 n = min_t(size_t, count, n);
1555 memcpy(read_buf_addr(ldata, head), cp, n);
1556 ldata->read_head += n;
1560 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1561 char *fp, int count)
1563 struct n_tty_data *ldata = tty->disc_data;
1564 char flag = TTY_NORMAL;
1569 if (likely(flag == TTY_NORMAL))
1570 put_tty_queue(*cp++, ldata);
1572 n_tty_receive_char_flagged(tty, *cp++, flag);
1577 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1578 char *fp, int count)
1580 char flag = TTY_NORMAL;
1585 if (likely(flag == TTY_NORMAL))
1586 n_tty_receive_char_closing(tty, *cp++);
1588 n_tty_receive_char_flagged(tty, *cp++, flag);
1593 n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1594 char *fp, int count)
1596 struct n_tty_data *ldata = tty->disc_data;
1597 char flag = TTY_NORMAL;
1602 if (likely(flag == TTY_NORMAL)) {
1603 unsigned char c = *cp++;
1607 if (I_IUCLC(tty) && L_IEXTEN(tty))
1609 if (L_EXTPROC(tty)) {
1610 put_tty_queue(c, ldata);
1613 if (!test_bit(c, ldata->char_map))
1614 n_tty_receive_char_inline(tty, c);
1615 else if (n_tty_receive_char_special(tty, c) && count) {
1618 n_tty_receive_char_lnext(tty, *cp++, flag);
1622 n_tty_receive_char_flagged(tty, *cp++, flag);
1627 n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1628 char *fp, int count)
1630 struct n_tty_data *ldata = tty->disc_data;
1631 char flag = TTY_NORMAL;
1636 if (likely(flag == TTY_NORMAL)) {
1637 unsigned char c = *cp++;
1639 if (!test_bit(c, ldata->char_map))
1640 n_tty_receive_char_fast(tty, c);
1641 else if (n_tty_receive_char_special(tty, c) && count) {
1644 n_tty_receive_char_lnext(tty, *cp++, flag);
1648 n_tty_receive_char_flagged(tty, *cp++, flag);
1652 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1653 char *fp, int count)
1655 struct n_tty_data *ldata = tty->disc_data;
1656 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1658 if (ldata->real_raw)
1659 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1660 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1661 n_tty_receive_buf_raw(tty, cp, fp, count);
1662 else if (tty->closing && !L_EXTPROC(tty))
1663 n_tty_receive_buf_closing(tty, cp, fp, count);
1666 char flag = TTY_NORMAL;
1670 n_tty_receive_char_lnext(tty, *cp++, flag);
1674 if (!preops && !I_PARMRK(tty))
1675 n_tty_receive_buf_fast(tty, cp, fp, count);
1677 n_tty_receive_buf_standard(tty, cp, fp, count);
1680 if (tty->ops->flush_chars)
1681 tty->ops->flush_chars(tty);
1684 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1686 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1687 if (waitqueue_active(&tty->read_wait))
1688 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1693 n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1694 char *fp, int count, int flow)
1696 struct n_tty_data *ldata = tty->disc_data;
1697 int room, n, rcvd = 0;
1699 down_read(&tty->termios_rwsem);
1702 room = receive_room(tty);
1703 n = min(count, room);
1709 __receive_buf(tty, cp, fp, n);
1717 tty->receive_room = room;
1718 n_tty_check_throttle(tty);
1719 up_read(&tty->termios_rwsem);
1724 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1725 char *fp, int count)
1727 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1730 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1731 char *fp, int count)
1733 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1736 int is_ignored(int sig)
1738 return (sigismember(¤t->blocked, sig) ||
1739 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1743 * n_tty_set_termios - termios data changed
1745 * @old: previous data
1747 * Called by the tty layer when the user changes termios flags so
1748 * that the line discipline can plan ahead. This function cannot sleep
1749 * and is protected from re-entry by the tty layer. The user is
1750 * guaranteed that this function will not be re-entered or in progress
1751 * when the ldisc is closed.
1753 * Locking: Caller holds tty->termios_rwsem
1756 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1758 struct n_tty_data *ldata = tty->disc_data;
1760 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1761 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1762 ldata->line_start = ldata->read_tail;
1763 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1764 ldata->canon_head = ldata->read_tail;
1767 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1769 ldata->canon_head = ldata->read_head;
1776 ldata->icanon = (L_ICANON(tty) != 0);
1778 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1779 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1780 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1782 bitmap_zero(ldata->char_map, 256);
1784 if (I_IGNCR(tty) || I_ICRNL(tty))
1785 set_bit('\r', ldata->char_map);
1787 set_bit('\n', ldata->char_map);
1789 if (L_ICANON(tty)) {
1790 set_bit(ERASE_CHAR(tty), ldata->char_map);
1791 set_bit(KILL_CHAR(tty), ldata->char_map);
1792 set_bit(EOF_CHAR(tty), ldata->char_map);
1793 set_bit('\n', ldata->char_map);
1794 set_bit(EOL_CHAR(tty), ldata->char_map);
1795 if (L_IEXTEN(tty)) {
1796 set_bit(WERASE_CHAR(tty), ldata->char_map);
1797 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1798 set_bit(EOL2_CHAR(tty), ldata->char_map);
1800 set_bit(REPRINT_CHAR(tty),
1805 set_bit(START_CHAR(tty), ldata->char_map);
1806 set_bit(STOP_CHAR(tty), ldata->char_map);
1809 set_bit(INTR_CHAR(tty), ldata->char_map);
1810 set_bit(QUIT_CHAR(tty), ldata->char_map);
1811 set_bit(SUSP_CHAR(tty), ldata->char_map);
1813 clear_bit(__DISABLED_CHAR, ldata->char_map);
1815 ldata->real_raw = 0;
1818 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1819 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1820 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1821 ldata->real_raw = 1;
1823 ldata->real_raw = 0;
1826 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1827 * been stopped by STOP_CHAR(tty) before it.
1829 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1831 process_echoes(tty);
1834 /* The termios change make the tty ready for I/O */
1835 if (waitqueue_active(&tty->write_wait))
1836 wake_up_interruptible(&tty->write_wait);
1837 if (waitqueue_active(&tty->read_wait))
1838 wake_up_interruptible(&tty->read_wait);
1842 * n_tty_close - close the ldisc for this tty
1845 * Called from the terminal layer when this line discipline is
1846 * being shut down, either because of a close or becsuse of a
1847 * discipline change. The function will not be called while other
1848 * ldisc methods are in progress.
1851 static void n_tty_close(struct tty_struct *tty)
1853 struct n_tty_data *ldata = tty->disc_data;
1856 n_tty_packet_mode_flush(tty);
1859 tty->disc_data = NULL;
1863 * n_tty_open - open an ldisc
1864 * @tty: terminal to open
1866 * Called when this line discipline is being attached to the
1867 * terminal device. Can sleep. Called serialized so that no
1868 * other events will occur in parallel. No further open will occur
1872 static int n_tty_open(struct tty_struct *tty)
1874 struct n_tty_data *ldata;
1876 /* Currently a malloc failure here can panic */
1877 ldata = vmalloc(sizeof(*ldata));
1881 ldata->overrun_time = jiffies;
1882 mutex_init(&ldata->atomic_read_lock);
1883 mutex_init(&ldata->output_lock);
1885 tty->disc_data = ldata;
1886 reset_buffer_flags(tty->disc_data);
1888 ldata->canon_column = 0;
1889 ldata->minimum_to_wake = 1;
1890 ldata->num_overrun = 0;
1894 /* indicate buffer work may resume */
1895 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1896 n_tty_set_termios(tty, NULL);
1897 tty_unthrottle(tty);
1904 static inline int input_available_p(struct tty_struct *tty, int poll)
1906 struct n_tty_data *ldata = tty->disc_data;
1907 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
1909 if (ldata->icanon && !L_EXTPROC(tty))
1910 return ldata->canon_head != ldata->read_tail;
1912 return read_cnt(ldata) >= amt;
1916 * copy_from_read_buf - copy read data directly
1917 * @tty: terminal device
1921 * Helper function to speed up n_tty_read. It is only called when
1922 * ICANON is off; it copies characters straight from the tty queue to
1923 * user space directly. It can be profitably called twice; once to
1924 * drain the space from the tail pointer to the (physical) end of the
1925 * buffer, and once to drain the space from the (physical) beginning of
1926 * the buffer to head pointer.
1928 * Called under the ldata->atomic_read_lock sem
1930 * n_tty_read()/consumer path:
1931 * caller holds non-exclusive termios_rwsem
1932 * read_tail published
1935 static int copy_from_read_buf(struct tty_struct *tty,
1936 unsigned char __user **b,
1940 struct n_tty_data *ldata = tty->disc_data;
1944 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1947 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1950 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1952 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1953 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1955 ldata->read_tail += n;
1956 /* Turn single EOF into zero-length read */
1957 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1966 * canon_copy_from_read_buf - copy read data in canonical mode
1967 * @tty: terminal device
1971 * Helper function for n_tty_read. It is only called when ICANON is on;
1972 * it copies one line of input up to and including the line-delimiting
1973 * character into the user-space buffer.
1975 * NB: When termios is changed from non-canonical to canonical mode and
1976 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1977 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1978 * This causes data already processed as input to be immediately available
1979 * as input although a newline has not been received.
1981 * Called under the atomic_read_lock mutex
1983 * n_tty_read()/consumer path:
1984 * caller holds non-exclusive termios_rwsem
1985 * read_tail published
1988 static int canon_copy_from_read_buf(struct tty_struct *tty,
1989 unsigned char __user **b,
1992 struct n_tty_data *ldata = tty->disc_data;
1993 size_t n, size, more, c;
1999 /* N.B. avoid overrun if nr == 0 */
2000 n = min(*nr, read_cnt(ldata));
2004 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
2005 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
2007 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2008 __func__, *nr, tail, n, size);
2010 eol = find_next_bit(ldata->read_flags, size, tail);
2011 more = n - (size - tail);
2012 if (eol == N_TTY_BUF_SIZE && more) {
2013 /* scan wrapped without finding set bit */
2014 eol = find_next_bit(ldata->read_flags, more, 0);
2017 } else if (eol != size)
2020 size = N_TTY_BUF_SIZE - tail;
2027 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
2029 eof_push = !n && ldata->read_tail != ldata->line_start;
2032 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2033 __func__, eol, found, n, c, size, more);
2036 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2039 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2041 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2049 clear_bit(eol, ldata->read_flags);
2050 smp_mb__after_atomic();
2051 ldata->read_tail += c;
2055 ldata->line_start = ldata->read_tail;
2058 tty_audit_push(tty);
2060 return eof_push ? -EAGAIN : 0;
2063 extern ssize_t redirected_tty_write(struct file *, const char __user *,
2067 * job_control - check job control
2069 * @file: file handle
2071 * Perform job control management checks on this file/tty descriptor
2072 * and if appropriate send any needed signals and return a negative
2073 * error code if action should be taken.
2075 * Locking: redirected write test is safe
2076 * current->signal->tty check is safe
2077 * ctrl_lock to safely reference tty->pgrp
2080 static int job_control(struct tty_struct *tty, struct file *file)
2082 /* Job control check -- must be done at start and after
2083 every sleep (POSIX.1 7.1.1.4). */
2084 /* NOTE: not yet done after every sleep pending a thorough
2085 check of the logic of this change. -- jlc */
2086 /* don't stop on /dev/console */
2087 if (file->f_op->write == redirected_tty_write ||
2088 current->signal->tty != tty)
2091 spin_lock_irq(&tty->ctrl_lock);
2093 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2094 else if (task_pgrp(current) != tty->pgrp) {
2095 spin_unlock_irq(&tty->ctrl_lock);
2096 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2098 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2099 set_thread_flag(TIF_SIGPENDING);
2100 return -ERESTARTSYS;
2102 spin_unlock_irq(&tty->ctrl_lock);
2108 * n_tty_read - read function for tty
2110 * @file: file object
2111 * @buf: userspace buffer pointer
2114 * Perform reads for the line discipline. We are guaranteed that the
2115 * line discipline will not be closed under us but we may get multiple
2116 * parallel readers and must handle this ourselves. We may also get
2117 * a hangup. Always called in user context, may sleep.
2119 * This code must be sure never to sleep through a hangup.
2121 * n_tty_read()/consumer path:
2122 * claims non-exclusive termios_rwsem
2123 * publishes read_tail
2126 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2127 unsigned char __user *buf, size_t nr)
2129 struct n_tty_data *ldata = tty->disc_data;
2130 unsigned char __user *b = buf;
2131 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2139 c = job_control(tty, file);
2144 * Internal serialization of reads.
2146 if (file->f_flags & O_NONBLOCK) {
2147 if (!mutex_trylock(&ldata->atomic_read_lock))
2150 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2151 return -ERESTARTSYS;
2154 down_read(&tty->termios_rwsem);
2157 timeout = MAX_SCHEDULE_TIMEOUT;
2158 if (!ldata->icanon) {
2159 minimum = MIN_CHAR(tty);
2161 time = (HZ / 10) * TIME_CHAR(tty);
2163 ldata->minimum_to_wake = 1;
2164 else if (!waitqueue_active(&tty->read_wait) ||
2165 (ldata->minimum_to_wake > minimum))
2166 ldata->minimum_to_wake = minimum;
2168 timeout = (HZ / 10) * TIME_CHAR(tty);
2169 ldata->minimum_to_wake = minimum = 1;
2173 packet = tty->packet;
2174 tail = ldata->read_tail;
2176 add_wait_queue(&tty->read_wait, &wait);
2178 /* First test for status change. */
2179 if (packet && tty->link->ctrl_status) {
2183 spin_lock_irq(&tty->link->ctrl_lock);
2184 cs = tty->link->ctrl_status;
2185 tty->link->ctrl_status = 0;
2186 spin_unlock_irq(&tty->link->ctrl_lock);
2187 if (tty_put_user(tty, cs, b++)) {
2196 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2197 ((minimum - (b - buf)) >= 1))
2198 ldata->minimum_to_wake = (minimum - (b - buf));
2200 if (!input_available_p(tty, 0)) {
2201 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2205 if (tty_hung_up_p(file))
2209 if (file->f_flags & O_NONBLOCK) {
2213 if (signal_pending(current)) {
2214 retval = -ERESTARTSYS;
2217 up_read(&tty->termios_rwsem);
2219 timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
2222 down_read(&tty->termios_rwsem);
2226 if (ldata->icanon && !L_EXTPROC(tty)) {
2227 retval = canon_copy_from_read_buf(tty, &b, &nr);
2228 if (retval == -EAGAIN) {
2236 /* Deal with packet mode. */
2237 if (packet && b == buf) {
2238 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2246 uncopied = copy_from_read_buf(tty, &b, &nr);
2247 uncopied += copy_from_read_buf(tty, &b, &nr);
2254 n_tty_check_unthrottle(tty);
2256 if (b - buf >= minimum)
2261 if (tail != ldata->read_tail)
2262 n_tty_kick_worker(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);
2278 * n_tty_write - write function for tty
2280 * @file: file object
2281 * @buf: userspace buffer pointer
2284 * Write function of the terminal device. This is serialized with
2285 * respect to other write callers but not to termios changes, reads
2286 * and other such events. Since the receive code will echo characters,
2287 * thus calling driver write methods, the output_lock is used in
2288 * the output processing functions called here as well as in the
2289 * echo processing function to protect the column state and space
2290 * left in the buffer.
2292 * This code must be sure never to sleep through a hangup.
2294 * Locking: output_lock to protect column state and space left
2295 * (note that the process_output*() functions take this
2299 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2300 const unsigned char *buf, size_t nr)
2302 const unsigned char *b = buf;
2303 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2307 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2308 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2309 retval = tty_check_change(tty);
2314 down_read(&tty->termios_rwsem);
2316 /* Write out any echoed characters that are still pending */
2317 process_echoes(tty);
2319 add_wait_queue(&tty->write_wait, &wait);
2321 if (signal_pending(current)) {
2322 retval = -ERESTARTSYS;
2325 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2331 ssize_t num = process_output_block(tty, b, nr);
2343 if (process_output(c, tty) < 0)
2347 if (tty->ops->flush_chars)
2348 tty->ops->flush_chars(tty);
2350 struct n_tty_data *ldata = tty->disc_data;
2353 mutex_lock(&ldata->output_lock);
2354 c = tty->ops->write(tty, b, nr);
2355 mutex_unlock(&ldata->output_lock);
2368 if (file->f_flags & O_NONBLOCK) {
2372 up_read(&tty->termios_rwsem);
2374 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
2376 down_read(&tty->termios_rwsem);
2379 remove_wait_queue(&tty->write_wait, &wait);
2380 if (b - buf != nr && tty->fasync)
2381 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2382 up_read(&tty->termios_rwsem);
2383 return (b - buf) ? b - buf : retval;
2387 * n_tty_poll - poll method for N_TTY
2388 * @tty: terminal device
2389 * @file: file accessing it
2392 * Called when the line discipline is asked to poll() for data or
2393 * for special events. This code is not serialized with respect to
2394 * other events save open/close.
2396 * This code must be sure never to sleep through a hangup.
2397 * Called without the kernel lock held - fine
2400 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2403 struct n_tty_data *ldata = tty->disc_data;
2404 unsigned int mask = 0;
2406 poll_wait(file, &tty->read_wait, wait);
2407 poll_wait(file, &tty->write_wait, wait);
2408 if (input_available_p(tty, 1))
2409 mask |= POLLIN | POLLRDNORM;
2410 if (tty->packet && tty->link->ctrl_status)
2411 mask |= POLLPRI | POLLIN | POLLRDNORM;
2412 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2414 if (tty_hung_up_p(file))
2416 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2417 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2418 ldata->minimum_to_wake = MIN_CHAR(tty);
2420 ldata->minimum_to_wake = 1;
2422 if (tty->ops->write && !tty_is_writelocked(tty) &&
2423 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2424 tty_write_room(tty) > 0)
2425 mask |= POLLOUT | POLLWRNORM;
2429 static unsigned long inq_canon(struct n_tty_data *ldata)
2431 size_t nr, head, tail;
2433 if (ldata->canon_head == ldata->read_tail)
2435 head = ldata->canon_head;
2436 tail = ldata->read_tail;
2438 /* Skip EOF-chars.. */
2439 while (head != tail) {
2440 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2441 read_buf(ldata, tail) == __DISABLED_CHAR)
2448 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2449 unsigned int cmd, unsigned long arg)
2451 struct n_tty_data *ldata = tty->disc_data;
2456 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2458 down_write(&tty->termios_rwsem);
2460 retval = inq_canon(ldata);
2462 retval = read_cnt(ldata);
2463 up_write(&tty->termios_rwsem);
2464 return put_user(retval, (unsigned int __user *) arg);
2466 return n_tty_ioctl_helper(tty, file, cmd, arg);
2470 static void n_tty_fasync(struct tty_struct *tty, int on)
2472 struct n_tty_data *ldata = tty->disc_data;
2474 if (!waitqueue_active(&tty->read_wait)) {
2476 ldata->minimum_to_wake = 1;
2477 else if (!tty->fasync)
2478 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2482 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2483 .magic = TTY_LDISC_MAGIC,
2486 .close = n_tty_close,
2487 .flush_buffer = n_tty_flush_buffer,
2488 .chars_in_buffer = n_tty_chars_in_buffer,
2490 .write = n_tty_write,
2491 .ioctl = n_tty_ioctl,
2492 .set_termios = n_tty_set_termios,
2494 .receive_buf = n_tty_receive_buf,
2495 .write_wakeup = n_tty_write_wakeup,
2496 .fasync = n_tty_fasync,
2497 .receive_buf2 = n_tty_receive_buf2,
2501 * n_tty_inherit_ops - inherit N_TTY methods
2502 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2504 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2508 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2510 *ops = tty_ldisc_N_TTY;
2512 ops->refcount = ops->flags = 0;
2514 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);