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;
108 /* shared by producer and consumer */
109 char read_buf[N_TTY_BUF_SIZE];
110 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
111 unsigned char echo_buf[N_TTY_BUF_SIZE];
115 /* consumer-published */
119 /* protected by output lock */
121 unsigned int canon_column;
124 struct mutex atomic_read_lock;
125 struct mutex output_lock;
128 static inline size_t read_cnt(struct n_tty_data *ldata)
130 return ldata->read_head - ldata->read_tail;
133 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
135 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
138 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
140 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
143 static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
145 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
148 static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
150 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
153 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
154 unsigned char __user *ptr)
156 struct n_tty_data *ldata = tty->disc_data;
158 tty_audit_add_data(tty, &x, 1, ldata->icanon);
159 return put_user(x, ptr);
162 static int receive_room(struct tty_struct *tty)
164 struct n_tty_data *ldata = tty->disc_data;
168 /* Multiply read_cnt by 3, since each byte might take up to
169 * three times as many spaces when PARMRK is set (depending on
170 * its flags, e.g. parity error). */
171 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
173 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
176 * If we are doing input canonicalization, and there are no
177 * pending newlines, let characters through without limit, so
178 * that erase characters will be handled. Other excess
179 * characters will be beeped.
182 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
188 * n_tty_set_room - receive space
191 * Re-schedules the flip buffer work if space just became available.
193 * Caller holds exclusive termios_rwsem
195 * n_tty_read()/consumer path:
196 * holds non-exclusive termios_rwsem
199 static void n_tty_set_room(struct tty_struct *tty)
201 struct n_tty_data *ldata = tty->disc_data;
203 /* Did this open up the receive buffer? We may need to flip */
204 if (unlikely(ldata->no_room) && receive_room(tty)) {
207 WARN_RATELIMIT(tty->port->itty == NULL,
208 "scheduling with invalid itty\n");
209 /* see if ldisc has been killed - if so, this means that
210 * even though the ldisc has been halted and ->buf.work
211 * cancelled, ->buf.work is about to be rescheduled
213 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
214 "scheduling buffer work for halted ldisc\n");
215 queue_work(system_unbound_wq, &tty->port->buf.work);
219 static ssize_t chars_in_buffer(struct tty_struct *tty)
221 struct n_tty_data *ldata = tty->disc_data;
227 n = ldata->canon_head - ldata->read_tail;
232 * n_tty_write_wakeup - asynchronous I/O notifier
235 * Required for the ptys, serial driver etc. since processes
236 * that attach themselves to the master and rely on ASYNC
237 * IO must be woken up
240 static void n_tty_write_wakeup(struct tty_struct *tty)
242 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
243 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
246 static void n_tty_check_throttle(struct tty_struct *tty)
248 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
251 * Check the remaining room for the input canonicalization
252 * mode. We don't want to throttle the driver if we're in
253 * canonical mode and don't have a newline yet!
257 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
258 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
260 throttled = tty_throttle_safe(tty);
264 __tty_set_flow_change(tty, 0);
267 static inline void n_tty_check_unthrottle(struct tty_struct *tty)
269 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
270 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
271 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
276 n_tty_write_wakeup(tty->link);
277 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
281 /* If there is enough space in the read buffer now, let the
282 * low-level driver know. We use chars_in_buffer() to
283 * check the buffer, as it now knows about canonical mode.
284 * Otherwise, if the driver is throttled and the line is
285 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
286 * we won't get any more characters.
291 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
292 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
297 unthrottled = tty_unthrottle_safe(tty);
301 __tty_set_flow_change(tty, 0);
305 * put_tty_queue - add character to tty
309 * Add a character to the tty read_buf queue.
311 * n_tty_receive_buf()/producer path:
312 * caller holds non-exclusive termios_rwsem
315 * read_head is only considered 'published' if canonical mode is
319 static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
321 if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
322 *read_buf_addr(ldata, ldata->read_head) = c;
328 * reset_buffer_flags - reset buffer state
329 * @tty: terminal to reset
331 * Reset the read buffer counters and clear the flags.
332 * Called from n_tty_open() and n_tty_flush_buffer().
334 * Locking: caller holds exclusive termios_rwsem
335 * (or locking is not required)
338 static void reset_buffer_flags(struct n_tty_data *ldata)
340 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
341 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
342 ldata->line_start = 0;
345 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 wake_up_interruptible(&tty->link->read_wait);
357 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
361 * n_tty_flush_buffer - clean input queue
362 * @tty: terminal device
364 * Flush the input buffer. Called when the tty layer wants the
365 * buffer flushed (eg at hangup) or when the N_TTY line discipline
366 * internally has to clean the pending queue (for example some signals).
368 * Holds termios_rwsem to exclude producer/consumer while
369 * buffer indices are reset.
371 * Locking: ctrl_lock, exclusive termios_rwsem
374 static void n_tty_flush_buffer(struct tty_struct *tty)
376 down_write(&tty->termios_rwsem);
377 reset_buffer_flags(tty->disc_data);
381 n_tty_packet_mode_flush(tty);
382 up_write(&tty->termios_rwsem);
386 * n_tty_chars_in_buffer - report available bytes
389 * Report the number of characters buffered to be delivered to user
390 * at this instant in time.
392 * Locking: exclusive termios_rwsem
395 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
399 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
401 down_write(&tty->termios_rwsem);
402 n = chars_in_buffer(tty);
403 up_write(&tty->termios_rwsem);
408 * is_utf8_continuation - utf8 multibyte check
411 * Returns true if the utf8 character 'c' is a multibyte continuation
412 * character. We use this to correctly compute the on screen size
413 * of the character when printing
416 static inline int is_utf8_continuation(unsigned char c)
418 return (c & 0xc0) == 0x80;
422 * is_continuation - multibyte check
425 * Returns true if the utf8 character 'c' is a multibyte continuation
426 * character and the terminal is in unicode mode.
429 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
431 return I_IUTF8(tty) && is_utf8_continuation(c);
435 * do_output_char - output one character
436 * @c: character (or partial unicode symbol)
437 * @tty: terminal device
438 * @space: space available in tty driver write buffer
440 * This is a helper function that handles one output character
441 * (including special characters like TAB, CR, LF, etc.),
442 * doing OPOST processing and putting the results in the
443 * tty driver's write buffer.
445 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
446 * and NLDLY. They simply aren't relevant in the world today.
447 * If you ever need them, add them here.
449 * Returns the number of bytes of buffer space used or -1 if
452 * Locking: should be called under the output_lock to protect
453 * the column state and space left in the buffer
456 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
458 struct n_tty_data *ldata = tty->disc_data;
471 ldata->canon_column = ldata->column = 0;
472 tty->ops->write(tty, "\r\n", 2);
475 ldata->canon_column = ldata->column;
478 if (O_ONOCR(tty) && ldata->column == 0)
483 ldata->canon_column = ldata->column = 0;
486 ldata->canon_column = ldata->column = 0;
489 spaces = 8 - (ldata->column & 7);
490 if (O_TABDLY(tty) == XTABS) {
493 ldata->column += spaces;
494 tty->ops->write(tty, " ", spaces);
497 ldata->column += spaces;
500 if (ldata->column > 0)
507 if (!is_continuation(c, tty))
513 tty_put_char(tty, c);
518 * process_output - output post processor
519 * @c: character (or partial unicode symbol)
520 * @tty: terminal device
522 * Output one character with OPOST processing.
523 * Returns -1 when the output device is full and the character
526 * Locking: output_lock to protect column state and space left
527 * (also, this is called from n_tty_write under the
528 * tty layer write lock)
531 static int process_output(unsigned char c, struct tty_struct *tty)
533 struct n_tty_data *ldata = tty->disc_data;
536 mutex_lock(&ldata->output_lock);
538 space = tty_write_room(tty);
539 retval = do_output_char(c, tty, space);
541 mutex_unlock(&ldata->output_lock);
549 * process_output_block - block post processor
550 * @tty: terminal device
551 * @buf: character buffer
552 * @nr: number of bytes to output
554 * Output a block of characters with OPOST processing.
555 * Returns the number of characters output.
557 * This path is used to speed up block console writes, among other
558 * things when processing blocks of output data. It handles only
559 * the simple cases normally found and helps to generate blocks of
560 * symbols for the console driver and thus improve performance.
562 * Locking: output_lock to protect column state and space left
563 * (also, this is called from n_tty_write under the
564 * tty layer write lock)
567 static ssize_t process_output_block(struct tty_struct *tty,
568 const unsigned char *buf, unsigned int nr)
570 struct n_tty_data *ldata = tty->disc_data;
573 const unsigned char *cp;
575 mutex_lock(&ldata->output_lock);
577 space = tty_write_room(tty);
579 mutex_unlock(&ldata->output_lock);
585 for (i = 0, cp = buf; i < nr; i++, cp++) {
586 unsigned char c = *cp;
594 ldata->canon_column = ldata->column;
597 if (O_ONOCR(tty) && ldata->column == 0)
601 ldata->canon_column = ldata->column = 0;
606 if (ldata->column > 0)
613 if (!is_continuation(c, tty))
620 i = tty->ops->write(tty, buf, i);
622 mutex_unlock(&ldata->output_lock);
627 * process_echoes - write pending echo characters
628 * @tty: terminal device
630 * Write previously buffered echo (and other ldisc-generated)
631 * characters to the tty.
633 * Characters generated by the ldisc (including echoes) need to
634 * be buffered because the driver's write buffer can fill during
635 * heavy program output. Echoing straight to the driver will
636 * often fail under these conditions, causing lost characters and
637 * resulting mismatches of ldisc state information.
639 * Since the ldisc state must represent the characters actually sent
640 * to the driver at the time of the write, operations like certain
641 * changes in column state are also saved in the buffer and executed
644 * A circular fifo buffer is used so that the most recent characters
645 * are prioritized. Also, when control characters are echoed with a
646 * prefixed "^", the pair is treated atomically and thus not separated.
648 * Locking: callers must hold output_lock
651 static size_t __process_echoes(struct tty_struct *tty)
653 struct n_tty_data *ldata = tty->disc_data;
654 int space, old_space;
658 old_space = space = tty_write_room(tty);
660 tail = ldata->echo_tail;
661 while (ldata->echo_commit != tail) {
662 c = echo_buf(ldata, tail);
663 if (c == ECHO_OP_START) {
665 int no_space_left = 0;
668 * If the buffer byte is the start of a multi-byte
669 * operation, get the next byte, which is either the
670 * op code or a control character value.
672 op = echo_buf(ldata, tail + 1);
675 unsigned int num_chars, num_bs;
677 case ECHO_OP_ERASE_TAB:
678 num_chars = echo_buf(ldata, tail + 2);
681 * Determine how many columns to go back
682 * in order to erase the tab.
683 * This depends on the number of columns
684 * used by other characters within the tab
685 * area. If this (modulo 8) count is from
686 * the start of input rather than from a
687 * previous tab, we offset by canon column.
688 * Otherwise, tab spacing is normal.
690 if (!(num_chars & 0x80))
691 num_chars += ldata->canon_column;
692 num_bs = 8 - (num_chars & 7);
694 if (num_bs > space) {
700 tty_put_char(tty, '\b');
701 if (ldata->column > 0)
707 case ECHO_OP_SET_CANON_COL:
708 ldata->canon_column = ldata->column;
712 case ECHO_OP_MOVE_BACK_COL:
713 if (ldata->column > 0)
719 /* This is an escaped echo op start code */
724 tty_put_char(tty, ECHO_OP_START);
732 * If the op is not a special byte code,
733 * it is a ctrl char tagged to be echoed
734 * as "^X" (where X is the letter
735 * representing the control char).
736 * Note that we must ensure there is
737 * enough space for the whole ctrl pair.
744 tty_put_char(tty, '^');
745 tty_put_char(tty, op ^ 0100);
755 int retval = do_output_char(c, tty, space);
762 tty_put_char(tty, c);
769 /* If the echo buffer is nearly full (so that the possibility exists
770 * of echo overrun before the next commit), then discard enough
771 * data at the tail to prevent a subsequent overrun */
772 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
773 if (echo_buf(ldata, tail == ECHO_OP_START)) {
774 if (echo_buf(ldata, tail) == ECHO_OP_ERASE_TAB)
782 ldata->echo_tail = tail;
783 return old_space - space;
786 static void commit_echoes(struct tty_struct *tty)
788 struct n_tty_data *ldata = tty->disc_data;
789 size_t nr, old, echoed;
792 head = ldata->echo_head;
793 old = ldata->echo_commit - ldata->echo_tail;
795 /* Process committed echoes if the accumulated # of bytes
796 * is over the threshold (and try again each time another
797 * block is accumulated) */
798 nr = head - ldata->echo_tail;
799 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
802 mutex_lock(&ldata->output_lock);
803 ldata->echo_commit = head;
804 echoed = __process_echoes(tty);
805 mutex_unlock(&ldata->output_lock);
807 if (echoed && tty->ops->flush_chars)
808 tty->ops->flush_chars(tty);
811 static void process_echoes(struct tty_struct *tty)
813 struct n_tty_data *ldata = tty->disc_data;
816 if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_tail)
819 mutex_lock(&ldata->output_lock);
820 echoed = __process_echoes(tty);
821 mutex_unlock(&ldata->output_lock);
823 if (echoed && tty->ops->flush_chars)
824 tty->ops->flush_chars(tty);
827 static void flush_echoes(struct tty_struct *tty)
829 struct n_tty_data *ldata = tty->disc_data;
831 if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_head)
834 mutex_lock(&ldata->output_lock);
835 ldata->echo_commit = ldata->echo_head;
836 __process_echoes(tty);
837 mutex_unlock(&ldata->output_lock);
841 * add_echo_byte - add a byte to the echo buffer
842 * @c: unicode byte to echo
845 * Add a character or operation byte to the echo buffer.
848 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
850 *echo_buf_addr(ldata, ldata->echo_head++) = c;
854 * echo_move_back_col - add operation to move back a column
857 * Add an operation to the echo buffer to move back one column.
860 static void echo_move_back_col(struct n_tty_data *ldata)
862 add_echo_byte(ECHO_OP_START, ldata);
863 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
867 * echo_set_canon_col - add operation to set the canon column
870 * Add an operation to the echo buffer to set the canon column
871 * to the current column.
874 static void echo_set_canon_col(struct n_tty_data *ldata)
876 add_echo_byte(ECHO_OP_START, ldata);
877 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
881 * echo_erase_tab - add operation to erase a tab
882 * @num_chars: number of character columns already used
883 * @after_tab: true if num_chars starts after a previous tab
886 * Add an operation to the echo buffer to erase a tab.
888 * Called by the eraser function, which knows how many character
889 * columns have been used since either a previous tab or the start
890 * of input. This information will be used later, along with
891 * canon column (if applicable), to go back the correct number
895 static void echo_erase_tab(unsigned int num_chars, int after_tab,
896 struct n_tty_data *ldata)
898 add_echo_byte(ECHO_OP_START, ldata);
899 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
901 /* We only need to know this modulo 8 (tab spacing) */
904 /* Set the high bit as a flag if num_chars is after a previous tab */
908 add_echo_byte(num_chars, ldata);
912 * echo_char_raw - echo a character raw
913 * @c: unicode byte to echo
914 * @tty: terminal device
916 * Echo user input back onto the screen. This must be called only when
917 * L_ECHO(tty) is true. Called from the driver receive_buf path.
919 * This variant does not treat control characters specially.
922 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
924 if (c == ECHO_OP_START) {
925 add_echo_byte(ECHO_OP_START, ldata);
926 add_echo_byte(ECHO_OP_START, ldata);
928 add_echo_byte(c, ldata);
933 * echo_char - echo a character
934 * @c: unicode byte to echo
935 * @tty: terminal device
937 * Echo user input back onto the screen. This must be called only when
938 * L_ECHO(tty) is true. Called from the driver receive_buf path.
940 * This variant tags control characters to be echoed as "^X"
941 * (where X is the letter representing the control char).
944 static void echo_char(unsigned char c, struct tty_struct *tty)
946 struct n_tty_data *ldata = tty->disc_data;
948 if (c == ECHO_OP_START) {
949 add_echo_byte(ECHO_OP_START, ldata);
950 add_echo_byte(ECHO_OP_START, ldata);
952 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
953 add_echo_byte(ECHO_OP_START, ldata);
954 add_echo_byte(c, ldata);
959 * finish_erasing - complete erase
963 static inline void finish_erasing(struct n_tty_data *ldata)
965 if (ldata->erasing) {
966 echo_char_raw('/', ldata);
972 * eraser - handle erase function
973 * @c: character input
974 * @tty: terminal device
976 * Perform erase and necessary output when an erase character is
977 * present in the stream from the driver layer. Handles the complexities
978 * of UTF-8 multibyte symbols.
980 * n_tty_receive_buf()/producer path:
981 * caller holds non-exclusive termios_rwsem
984 * Modifying the read_head is not considered a publish in this context
985 * because canonical mode is active -- only canon_head publishes
988 static void eraser(unsigned char c, struct tty_struct *tty)
990 struct n_tty_data *ldata = tty->disc_data;
991 enum { ERASE, WERASE, KILL } kill_type;
996 if (ldata->read_head == ldata->canon_head) {
997 /* process_output('\a', tty); */ /* what do you think? */
1000 if (c == ERASE_CHAR(tty))
1002 else if (c == WERASE_CHAR(tty))
1006 ldata->read_head = ldata->canon_head;
1009 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1010 ldata->read_head = ldata->canon_head;
1011 finish_erasing(ldata);
1012 echo_char(KILL_CHAR(tty), tty);
1013 /* Add a newline if ECHOK is on and ECHOKE is off. */
1015 echo_char_raw('\n', ldata);
1022 while (ldata->read_head != ldata->canon_head) {
1023 head = ldata->read_head;
1025 /* erase a single possibly multibyte character */
1028 c = read_buf(ldata, head);
1029 } while (is_continuation(c, tty) && head != ldata->canon_head);
1031 /* do not partially erase */
1032 if (is_continuation(c, tty))
1035 if (kill_type == WERASE) {
1036 /* Equivalent to BSD's ALTWERASE. */
1037 if (isalnum(c) || c == '_')
1039 else if (seen_alnums)
1042 cnt = ldata->read_head - head;
1043 ldata->read_head = head;
1045 if (L_ECHOPRT(tty)) {
1046 if (!ldata->erasing) {
1047 echo_char_raw('\\', ldata);
1050 /* if cnt > 1, output a multi-byte character */
1054 echo_char_raw(read_buf(ldata, head), ldata);
1055 echo_move_back_col(ldata);
1057 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1058 echo_char(ERASE_CHAR(tty), tty);
1059 } else if (c == '\t') {
1060 unsigned int num_chars = 0;
1062 size_t tail = ldata->read_head;
1065 * Count the columns used for characters
1066 * since the start of input or after a
1068 * This info is used to go back the correct
1069 * number of columns.
1071 while (tail != ldata->canon_head) {
1073 c = read_buf(ldata, tail);
1077 } else if (iscntrl(c)) {
1080 } else if (!is_continuation(c, tty)) {
1084 echo_erase_tab(num_chars, after_tab, ldata);
1086 if (iscntrl(c) && L_ECHOCTL(tty)) {
1087 echo_char_raw('\b', ldata);
1088 echo_char_raw(' ', ldata);
1089 echo_char_raw('\b', ldata);
1091 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1092 echo_char_raw('\b', ldata);
1093 echo_char_raw(' ', ldata);
1094 echo_char_raw('\b', ldata);
1098 if (kill_type == ERASE)
1101 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1102 finish_erasing(ldata);
1106 * isig - handle the ISIG optio
1110 * Called when a signal is being sent due to terminal input.
1111 * Called from the driver receive_buf path so serialized.
1113 * Locking: ctrl_lock
1116 static inline void isig(int sig, struct tty_struct *tty)
1118 struct pid *tty_pgrp = tty_get_pgrp(tty);
1120 kill_pgrp(tty_pgrp, sig, 1);
1126 * n_tty_receive_break - handle break
1129 * An RS232 break event has been hit in the incoming bitstream. This
1130 * can cause a variety of events depending upon the termios settings.
1132 * n_tty_receive_buf()/producer path:
1133 * caller holds non-exclusive termios_rwsem
1134 * publishes read_head via put_tty_queue()
1136 * Note: may get exclusive termios_rwsem if flushing input buffer
1139 static inline void n_tty_receive_break(struct tty_struct *tty)
1141 struct n_tty_data *ldata = tty->disc_data;
1145 if (I_BRKINT(tty)) {
1147 if (!L_NOFLSH(tty)) {
1148 /* flushing needs exclusive termios_rwsem */
1149 up_read(&tty->termios_rwsem);
1150 n_tty_flush_buffer(tty);
1151 tty_driver_flush_buffer(tty);
1152 down_read(&tty->termios_rwsem);
1156 if (I_PARMRK(tty)) {
1157 put_tty_queue('\377', ldata);
1158 put_tty_queue('\0', ldata);
1160 put_tty_queue('\0', ldata);
1161 wake_up_interruptible(&tty->read_wait);
1165 * n_tty_receive_overrun - handle overrun reporting
1168 * Data arrived faster than we could process it. While the tty
1169 * driver has flagged this the bits that were missed are gone
1172 * Called from the receive_buf path so single threaded. Does not
1173 * need locking as num_overrun and overrun_time are function
1177 static inline void n_tty_receive_overrun(struct tty_struct *tty)
1179 struct n_tty_data *ldata = tty->disc_data;
1182 ldata->num_overrun++;
1183 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1184 time_after(ldata->overrun_time, jiffies)) {
1185 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1187 ldata->num_overrun);
1188 ldata->overrun_time = jiffies;
1189 ldata->num_overrun = 0;
1194 * n_tty_receive_parity_error - error notifier
1195 * @tty: terminal device
1198 * Process a parity error and queue the right data to indicate
1199 * the error case if necessary.
1201 * n_tty_receive_buf()/producer path:
1202 * caller holds non-exclusive termios_rwsem
1203 * publishes read_head via put_tty_queue()
1205 static inline void n_tty_receive_parity_error(struct tty_struct *tty,
1208 struct n_tty_data *ldata = tty->disc_data;
1212 if (I_PARMRK(tty)) {
1213 put_tty_queue('\377', ldata);
1214 put_tty_queue('\0', ldata);
1215 put_tty_queue(c, ldata);
1216 } else if (I_INPCK(tty))
1217 put_tty_queue('\0', ldata);
1219 put_tty_queue(c, ldata);
1220 wake_up_interruptible(&tty->read_wait);
1224 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1226 if (!L_NOFLSH(tty)) {
1227 /* flushing needs exclusive termios_rwsem */
1228 up_read(&tty->termios_rwsem);
1229 n_tty_flush_buffer(tty);
1230 tty_driver_flush_buffer(tty);
1231 down_read(&tty->termios_rwsem);
1244 * n_tty_receive_char - perform processing
1245 * @tty: terminal device
1248 * Process an individual character of input received from the driver.
1249 * This is serialized with respect to itself by the rules for the
1252 * n_tty_receive_buf()/producer path:
1253 * caller holds non-exclusive termios_rwsem
1254 * publishes canon_head if canonical mode is active
1255 * otherwise, publishes read_head via put_tty_queue()
1258 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1260 struct n_tty_data *ldata = tty->disc_data;
1265 if (I_IUCLC(tty) && L_IEXTEN(tty))
1268 if (L_EXTPROC(tty)) {
1269 put_tty_queue(c, ldata);
1273 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
1274 I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) &&
1275 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) {
1277 process_echoes(tty);
1281 * If the previous character was LNEXT, or we know that this
1282 * character is not one of the characters that we'll have to
1283 * handle specially, do shortcut processing to speed things
1286 if (!test_bit(c, ldata->char_map) || ldata->lnext) {
1288 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1289 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1290 /* beep if no space */
1292 process_output('\a', tty);
1296 finish_erasing(ldata);
1297 /* Record the column of first canon char. */
1298 if (ldata->canon_head == ldata->read_head)
1299 echo_set_canon_col(ldata);
1304 put_tty_queue(c, ldata);
1305 put_tty_queue(c, ldata);
1310 if (c == START_CHAR(tty)) {
1315 if (c == STOP_CHAR(tty)) {
1322 if (c == INTR_CHAR(tty)) {
1323 n_tty_receive_signal_char(tty, SIGINT, c);
1325 } else if (c == QUIT_CHAR(tty)) {
1326 n_tty_receive_signal_char(tty, SIGQUIT, c);
1328 } else if (c == SUSP_CHAR(tty)) {
1329 n_tty_receive_signal_char(tty, SIGTSTP, c);
1339 } else if (c == '\n' && I_INLCR(tty))
1342 if (ldata->icanon) {
1343 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1344 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1349 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1352 finish_erasing(ldata);
1353 if (L_ECHOCTL(tty)) {
1354 echo_char_raw('^', ldata);
1355 echo_char_raw('\b', ldata);
1361 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
1363 size_t tail = ldata->canon_head;
1365 finish_erasing(ldata);
1367 echo_char_raw('\n', ldata);
1368 while (tail != ldata->read_head) {
1369 echo_char(read_buf(ldata, tail), tty);
1376 if (read_cnt(ldata) >= N_TTY_BUF_SIZE) {
1378 process_output('\a', tty);
1381 if (L_ECHO(tty) || L_ECHONL(tty)) {
1382 echo_char_raw('\n', ldata);
1385 goto handle_newline;
1387 if (c == EOF_CHAR(tty)) {
1388 if (read_cnt(ldata) >= N_TTY_BUF_SIZE)
1390 c = __DISABLED_CHAR;
1391 goto handle_newline;
1393 if ((c == EOL_CHAR(tty)) ||
1394 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1395 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1397 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) {
1399 process_output('\a', tty);
1403 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1406 /* Record the column of first canon char. */
1407 if (ldata->canon_head == ldata->read_head)
1408 echo_set_canon_col(ldata);
1413 * XXX does PARMRK doubling happen for
1414 * EOL_CHAR and EOL2_CHAR?
1417 put_tty_queue(c, ldata);
1420 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1421 put_tty_queue(c, ldata);
1422 ldata->canon_head = ldata->read_head;
1423 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1424 if (waitqueue_active(&tty->read_wait))
1425 wake_up_interruptible(&tty->read_wait);
1430 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1431 if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
1432 /* beep if no space */
1434 process_output('\a', tty);
1438 finish_erasing(ldata);
1440 echo_char_raw('\n', ldata);
1442 /* Record the column of first canon char. */
1443 if (ldata->canon_head == ldata->read_head)
1444 echo_set_canon_col(ldata);
1451 put_tty_queue(c, ldata);
1453 put_tty_queue(c, ldata);
1457 n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1461 if (I_IUCLC(tty) && L_IEXTEN(tty))
1465 if (c == STOP_CHAR(tty))
1467 else if (c == START_CHAR(tty) ||
1468 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1469 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1470 c != SUSP_CHAR(tty))) {
1472 process_echoes(tty);
1478 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1484 n_tty_receive_break(tty);
1488 n_tty_receive_parity_error(tty, c);
1491 n_tty_receive_overrun(tty);
1494 printk(KERN_ERR "%s: unknown flag %d\n",
1495 tty_name(tty, buf), flag);
1501 * n_tty_receive_buf - data receive
1502 * @tty: terminal device
1505 * @count: characters
1507 * Called by the terminal driver when a block of characters has
1508 * been received. This function must be called from soft contexts
1509 * not from interrupt context. The driver is responsible for making
1510 * calls one at a time and in order (or using flush_to_ldisc)
1512 * n_tty_receive_buf()/producer path:
1513 * claims non-exclusive termios_rwsem
1514 * publishes read_head and canon_head
1518 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1519 char *fp, int count)
1521 struct n_tty_data *ldata = tty->disc_data;
1524 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1525 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1526 n = min_t(size_t, count, n);
1527 memcpy(read_buf_addr(ldata, head), cp, n);
1528 ldata->read_head += n;
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 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1541 char *fp, int count)
1543 struct n_tty_data *ldata = tty->disc_data;
1544 char flag = TTY_NORMAL;
1549 if (likely(flag == TTY_NORMAL))
1550 put_tty_queue(*cp++, ldata);
1552 n_tty_receive_char_flagged(tty, *cp++, flag);
1557 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1558 char *fp, int count)
1560 char flag = TTY_NORMAL;
1565 if (likely(flag == TTY_NORMAL))
1566 n_tty_receive_char_closing(tty, *cp++);
1568 n_tty_receive_char_flagged(tty, *cp++, flag);
1572 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1573 char *fp, int count)
1575 struct n_tty_data *ldata = tty->disc_data;
1576 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1578 if (ldata->real_raw)
1579 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1580 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1581 n_tty_receive_buf_raw(tty, cp, fp, count);
1582 else if (tty->closing && !L_EXTPROC(tty))
1583 n_tty_receive_buf_closing(tty, cp, fp, count);
1585 char flag = TTY_NORMAL;
1590 if (likely(flag == TTY_NORMAL))
1591 n_tty_receive_char(tty, *cp++);
1593 n_tty_receive_char_flagged(tty, *cp++, flag);
1597 if (tty->ops->flush_chars)
1598 tty->ops->flush_chars(tty);
1601 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1603 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1604 if (waitqueue_active(&tty->read_wait))
1605 wake_up_interruptible(&tty->read_wait);
1609 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1610 char *fp, int count)
1612 down_read(&tty->termios_rwsem);
1613 __receive_buf(tty, cp, fp, count);
1614 n_tty_check_throttle(tty);
1615 up_read(&tty->termios_rwsem);
1618 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1619 char *fp, int count)
1621 struct n_tty_data *ldata = tty->disc_data;
1624 down_read(&tty->termios_rwsem);
1626 tty->receive_room = room = receive_room(tty);
1629 count = min(count, room);
1631 __receive_buf(tty, cp, fp, count);
1632 n_tty_check_throttle(tty);
1635 up_read(&tty->termios_rwsem);
1640 int is_ignored(int sig)
1642 return (sigismember(¤t->blocked, sig) ||
1643 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1647 * n_tty_set_termios - termios data changed
1649 * @old: previous data
1651 * Called by the tty layer when the user changes termios flags so
1652 * that the line discipline can plan ahead. This function cannot sleep
1653 * and is protected from re-entry by the tty layer. The user is
1654 * guaranteed that this function will not be re-entered or in progress
1655 * when the ldisc is closed.
1657 * Locking: Caller holds tty->termios_rwsem
1660 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1662 struct n_tty_data *ldata = tty->disc_data;
1663 int canon_change = 1;
1666 canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
1668 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1669 ldata->line_start = 0;
1670 ldata->canon_head = ldata->read_tail;
1675 if (canon_change && !L_ICANON(tty) && read_cnt(ldata))
1676 wake_up_interruptible(&tty->read_wait);
1678 ldata->icanon = (L_ICANON(tty) != 0);
1680 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1681 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1682 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1684 bitmap_zero(ldata->char_map, 256);
1686 if (I_IGNCR(tty) || I_ICRNL(tty))
1687 set_bit('\r', ldata->char_map);
1689 set_bit('\n', ldata->char_map);
1691 if (L_ICANON(tty)) {
1692 set_bit(ERASE_CHAR(tty), ldata->char_map);
1693 set_bit(KILL_CHAR(tty), ldata->char_map);
1694 set_bit(EOF_CHAR(tty), ldata->char_map);
1695 set_bit('\n', ldata->char_map);
1696 set_bit(EOL_CHAR(tty), ldata->char_map);
1697 if (L_IEXTEN(tty)) {
1698 set_bit(WERASE_CHAR(tty), ldata->char_map);
1699 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1700 set_bit(EOL2_CHAR(tty), ldata->char_map);
1702 set_bit(REPRINT_CHAR(tty),
1707 set_bit(START_CHAR(tty), ldata->char_map);
1708 set_bit(STOP_CHAR(tty), ldata->char_map);
1711 set_bit(INTR_CHAR(tty), ldata->char_map);
1712 set_bit(QUIT_CHAR(tty), ldata->char_map);
1713 set_bit(SUSP_CHAR(tty), ldata->char_map);
1715 clear_bit(__DISABLED_CHAR, ldata->char_map);
1717 ldata->real_raw = 0;
1720 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1721 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1722 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1723 ldata->real_raw = 1;
1725 ldata->real_raw = 0;
1727 n_tty_set_room(tty);
1729 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1730 * been stopped by STOP_CHAR(tty) before it.
1732 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1736 /* The termios change make the tty ready for I/O */
1737 wake_up_interruptible(&tty->write_wait);
1738 wake_up_interruptible(&tty->read_wait);
1742 * n_tty_close - close the ldisc for this tty
1745 * Called from the terminal layer when this line discipline is
1746 * being shut down, either because of a close or becsuse of a
1747 * discipline change. The function will not be called while other
1748 * ldisc methods are in progress.
1751 static void n_tty_close(struct tty_struct *tty)
1753 struct n_tty_data *ldata = tty->disc_data;
1756 n_tty_packet_mode_flush(tty);
1759 tty->disc_data = NULL;
1763 * n_tty_open - open an ldisc
1764 * @tty: terminal to open
1766 * Called when this line discipline is being attached to the
1767 * terminal device. Can sleep. Called serialized so that no
1768 * other events will occur in parallel. No further open will occur
1772 static int n_tty_open(struct tty_struct *tty)
1774 struct n_tty_data *ldata;
1776 /* Currently a malloc failure here can panic */
1777 ldata = vmalloc(sizeof(*ldata));
1781 ldata->overrun_time = jiffies;
1782 mutex_init(&ldata->atomic_read_lock);
1783 mutex_init(&ldata->output_lock);
1785 tty->disc_data = ldata;
1786 reset_buffer_flags(tty->disc_data);
1788 ldata->canon_column = 0;
1789 ldata->minimum_to_wake = 1;
1790 ldata->num_overrun = 0;
1794 /* indicate buffer work may resume */
1795 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1796 n_tty_set_termios(tty, NULL);
1797 tty_unthrottle(tty);
1804 static inline int input_available_p(struct tty_struct *tty, int amt)
1806 struct n_tty_data *ldata = tty->disc_data;
1808 if (ldata->icanon && !L_EXTPROC(tty)) {
1809 if (ldata->canon_head != ldata->read_tail)
1811 } else if (read_cnt(ldata) >= (amt ? amt : 1))
1818 * copy_from_read_buf - copy read data directly
1819 * @tty: terminal device
1823 * Helper function to speed up n_tty_read. It is only called when
1824 * ICANON is off; it copies characters straight from the tty queue to
1825 * user space directly. It can be profitably called twice; once to
1826 * drain the space from the tail pointer to the (physical) end of the
1827 * buffer, and once to drain the space from the (physical) beginning of
1828 * the buffer to head pointer.
1830 * Called under the ldata->atomic_read_lock sem
1832 * n_tty_read()/consumer path:
1833 * caller holds non-exclusive termios_rwsem
1834 * read_tail published
1837 static int copy_from_read_buf(struct tty_struct *tty,
1838 unsigned char __user **b,
1842 struct n_tty_data *ldata = tty->disc_data;
1846 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1849 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1852 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1854 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1855 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1857 ldata->read_tail += n;
1858 /* Turn single EOF into zero-length read */
1859 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1868 * canon_copy_from_read_buf - copy read data in canonical mode
1869 * @tty: terminal device
1873 * Helper function for n_tty_read. It is only called when ICANON is on;
1874 * it copies one line of input up to and including the line-delimiting
1875 * character into the user-space buffer.
1877 * Called under the atomic_read_lock mutex
1879 * n_tty_read()/consumer path:
1880 * caller holds non-exclusive termios_rwsem
1881 * read_tail published
1884 static int canon_copy_from_read_buf(struct tty_struct *tty,
1885 unsigned char __user **b,
1888 struct n_tty_data *ldata = tty->disc_data;
1889 size_t n, size, more, c;
1895 /* N.B. avoid overrun if nr == 0 */
1896 n = min(*nr, read_cnt(ldata));
1900 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1901 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
1903 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1904 __func__, *nr, tail, n, size);
1906 eol = find_next_bit(ldata->read_flags, size, tail);
1907 more = n - (size - tail);
1908 if (eol == N_TTY_BUF_SIZE && more) {
1909 /* scan wrapped without finding set bit */
1910 eol = find_next_bit(ldata->read_flags, more, 0);
1913 } else if (eol != size)
1916 size = N_TTY_BUF_SIZE - tail;
1917 n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
1920 if (found && read_buf(ldata, eol) == __DISABLED_CHAR) {
1922 eof_push = !n && ldata->read_tail != ldata->line_start;
1925 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
1926 __func__, eol, found, n, c, size, more);
1929 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
1932 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
1934 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1942 clear_bit(eol, ldata->read_flags);
1943 smp_mb__after_clear_bit();
1944 ldata->read_tail += c;
1947 ldata->line_start = ldata->read_tail;
1948 tty_audit_push(tty);
1950 return eof_push ? -EAGAIN : 0;
1953 extern ssize_t redirected_tty_write(struct file *, const char __user *,
1957 * job_control - check job control
1959 * @file: file handle
1961 * Perform job control management checks on this file/tty descriptor
1962 * and if appropriate send any needed signals and return a negative
1963 * error code if action should be taken.
1965 * Locking: redirected write test is safe
1966 * current->signal->tty check is safe
1967 * ctrl_lock to safely reference tty->pgrp
1970 static int job_control(struct tty_struct *tty, struct file *file)
1972 /* Job control check -- must be done at start and after
1973 every sleep (POSIX.1 7.1.1.4). */
1974 /* NOTE: not yet done after every sleep pending a thorough
1975 check of the logic of this change. -- jlc */
1976 /* don't stop on /dev/console */
1977 if (file->f_op->write == redirected_tty_write ||
1978 current->signal->tty != tty)
1981 spin_lock_irq(&tty->ctrl_lock);
1983 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
1984 else if (task_pgrp(current) != tty->pgrp) {
1985 spin_unlock_irq(&tty->ctrl_lock);
1986 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
1988 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
1989 set_thread_flag(TIF_SIGPENDING);
1990 return -ERESTARTSYS;
1992 spin_unlock_irq(&tty->ctrl_lock);
1998 * n_tty_read - read function for tty
2000 * @file: file object
2001 * @buf: userspace buffer pointer
2004 * Perform reads for the line discipline. We are guaranteed that the
2005 * line discipline will not be closed under us but we may get multiple
2006 * parallel readers and must handle this ourselves. We may also get
2007 * a hangup. Always called in user context, may sleep.
2009 * This code must be sure never to sleep through a hangup.
2011 * n_tty_read()/consumer path:
2012 * claims non-exclusive termios_rwsem
2013 * publishes read_tail
2016 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2017 unsigned char __user *buf, size_t nr)
2019 struct n_tty_data *ldata = tty->disc_data;
2020 unsigned char __user *b = buf;
2021 DECLARE_WAITQUEUE(wait, current);
2026 unsigned long flags;
2029 c = job_control(tty, file);
2033 down_read(&tty->termios_rwsem);
2036 timeout = MAX_SCHEDULE_TIMEOUT;
2037 if (!ldata->icanon) {
2038 minimum = MIN_CHAR(tty);
2040 time = (HZ / 10) * TIME_CHAR(tty);
2042 ldata->minimum_to_wake = 1;
2043 else if (!waitqueue_active(&tty->read_wait) ||
2044 (ldata->minimum_to_wake > minimum))
2045 ldata->minimum_to_wake = minimum;
2047 timeout = (HZ / 10) * TIME_CHAR(tty);
2048 ldata->minimum_to_wake = minimum = 1;
2053 * Internal serialization of reads.
2055 if (file->f_flags & O_NONBLOCK) {
2056 if (!mutex_trylock(&ldata->atomic_read_lock)) {
2057 up_read(&tty->termios_rwsem);
2061 if (mutex_lock_interruptible(&ldata->atomic_read_lock)) {
2062 up_read(&tty->termios_rwsem);
2063 return -ERESTARTSYS;
2066 packet = tty->packet;
2068 add_wait_queue(&tty->read_wait, &wait);
2070 /* First test for status change. */
2071 if (packet && tty->link->ctrl_status) {
2075 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
2076 cs = tty->link->ctrl_status;
2077 tty->link->ctrl_status = 0;
2078 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2079 if (tty_put_user(tty, cs, b++)) {
2087 /* This statement must be first before checking for input
2088 so that any interrupt will set the state back to
2090 set_current_state(TASK_INTERRUPTIBLE);
2092 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2093 ((minimum - (b - buf)) >= 1))
2094 ldata->minimum_to_wake = (minimum - (b - buf));
2096 if (!input_available_p(tty, 0)) {
2097 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2101 if (tty_hung_up_p(file))
2105 if (file->f_flags & O_NONBLOCK) {
2109 if (signal_pending(current)) {
2110 retval = -ERESTARTSYS;
2113 n_tty_set_room(tty);
2114 up_read(&tty->termios_rwsem);
2116 timeout = schedule_timeout(timeout);
2118 down_read(&tty->termios_rwsem);
2121 __set_current_state(TASK_RUNNING);
2123 /* Deal with packet mode. */
2124 if (packet && b == buf) {
2125 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2133 if (ldata->icanon && !L_EXTPROC(tty)) {
2134 retval = canon_copy_from_read_buf(tty, &b, &nr);
2135 if (retval == -EAGAIN) {
2142 /* The copy function takes the read lock and handles
2143 locking internally for this case */
2144 uncopied = copy_from_read_buf(tty, &b, &nr);
2145 uncopied += copy_from_read_buf(tty, &b, &nr);
2152 n_tty_check_unthrottle(tty);
2154 if (b - buf >= minimum)
2159 mutex_unlock(&ldata->atomic_read_lock);
2160 remove_wait_queue(&tty->read_wait, &wait);
2162 if (!waitqueue_active(&tty->read_wait))
2163 ldata->minimum_to_wake = minimum;
2165 __set_current_state(TASK_RUNNING);
2169 n_tty_set_room(tty);
2170 up_read(&tty->termios_rwsem);
2175 * n_tty_write - write function for tty
2177 * @file: file object
2178 * @buf: userspace buffer pointer
2181 * Write function of the terminal device. This is serialized with
2182 * respect to other write callers but not to termios changes, reads
2183 * and other such events. Since the receive code will echo characters,
2184 * thus calling driver write methods, the output_lock is used in
2185 * the output processing functions called here as well as in the
2186 * echo processing function to protect the column state and space
2187 * left in the buffer.
2189 * This code must be sure never to sleep through a hangup.
2191 * Locking: output_lock to protect column state and space left
2192 * (note that the process_output*() functions take this
2196 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2197 const unsigned char *buf, size_t nr)
2199 const unsigned char *b = buf;
2200 DECLARE_WAITQUEUE(wait, current);
2204 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2205 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2206 retval = tty_check_change(tty);
2211 down_read(&tty->termios_rwsem);
2213 /* Write out any echoed characters that are still pending */
2214 process_echoes(tty);
2216 add_wait_queue(&tty->write_wait, &wait);
2218 set_current_state(TASK_INTERRUPTIBLE);
2219 if (signal_pending(current)) {
2220 retval = -ERESTARTSYS;
2223 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2229 ssize_t num = process_output_block(tty, b, nr);
2241 if (process_output(c, tty) < 0)
2245 if (tty->ops->flush_chars)
2246 tty->ops->flush_chars(tty);
2249 c = tty->ops->write(tty, b, nr);
2262 if (file->f_flags & O_NONBLOCK) {
2266 up_read(&tty->termios_rwsem);
2270 down_read(&tty->termios_rwsem);
2273 __set_current_state(TASK_RUNNING);
2274 remove_wait_queue(&tty->write_wait, &wait);
2275 if (b - buf != nr && tty->fasync)
2276 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2277 up_read(&tty->termios_rwsem);
2278 return (b - buf) ? b - buf : retval;
2282 * n_tty_poll - poll method for N_TTY
2283 * @tty: terminal device
2284 * @file: file accessing it
2287 * Called when the line discipline is asked to poll() for data or
2288 * for special events. This code is not serialized with respect to
2289 * other events save open/close.
2291 * This code must be sure never to sleep through a hangup.
2292 * Called without the kernel lock held - fine
2295 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2298 struct n_tty_data *ldata = tty->disc_data;
2299 unsigned int mask = 0;
2301 poll_wait(file, &tty->read_wait, wait);
2302 poll_wait(file, &tty->write_wait, wait);
2303 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2304 mask |= POLLIN | POLLRDNORM;
2305 if (tty->packet && tty->link->ctrl_status)
2306 mask |= POLLPRI | POLLIN | POLLRDNORM;
2307 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2309 if (tty_hung_up_p(file))
2311 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2312 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2313 ldata->minimum_to_wake = MIN_CHAR(tty);
2315 ldata->minimum_to_wake = 1;
2317 if (tty->ops->write && !tty_is_writelocked(tty) &&
2318 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2319 tty_write_room(tty) > 0)
2320 mask |= POLLOUT | POLLWRNORM;
2324 static unsigned long inq_canon(struct n_tty_data *ldata)
2326 size_t nr, head, tail;
2328 if (ldata->canon_head == ldata->read_tail)
2330 head = ldata->canon_head;
2331 tail = ldata->read_tail;
2333 /* Skip EOF-chars.. */
2334 while (head != tail) {
2335 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2336 read_buf(ldata, tail) == __DISABLED_CHAR)
2343 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2344 unsigned int cmd, unsigned long arg)
2346 struct n_tty_data *ldata = tty->disc_data;
2351 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2353 down_write(&tty->termios_rwsem);
2355 retval = inq_canon(ldata);
2357 retval = read_cnt(ldata);
2358 up_write(&tty->termios_rwsem);
2359 return put_user(retval, (unsigned int __user *) arg);
2361 return n_tty_ioctl_helper(tty, file, cmd, arg);
2365 static void n_tty_fasync(struct tty_struct *tty, int on)
2367 struct n_tty_data *ldata = tty->disc_data;
2369 if (!waitqueue_active(&tty->read_wait)) {
2371 ldata->minimum_to_wake = 1;
2372 else if (!tty->fasync)
2373 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2377 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2378 .magic = TTY_LDISC_MAGIC,
2381 .close = n_tty_close,
2382 .flush_buffer = n_tty_flush_buffer,
2383 .chars_in_buffer = n_tty_chars_in_buffer,
2385 .write = n_tty_write,
2386 .ioctl = n_tty_ioctl,
2387 .set_termios = n_tty_set_termios,
2389 .receive_buf = n_tty_receive_buf,
2390 .write_wakeup = n_tty_write_wakeup,
2391 .fasync = n_tty_fasync,
2392 .receive_buf2 = n_tty_receive_buf2,
2396 * n_tty_inherit_ops - inherit N_TTY methods
2397 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2399 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2403 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2405 *ops = tty_ldisc_N_TTY;
2407 ops->refcount = ops->flags = 0;
2409 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);