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_set_room - receive space
193 * Re-schedules the flip buffer work if space just became available.
195 * Caller holds exclusive termios_rwsem
197 * n_tty_read()/consumer path:
198 * holds non-exclusive termios_rwsem
201 static void n_tty_set_room(struct tty_struct *tty)
203 struct n_tty_data *ldata = tty->disc_data;
205 /* Did this open up the receive buffer? We may need to flip */
206 if (unlikely(ldata->no_room) && receive_room(tty)) {
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 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
253 * Check the remaining room for the input canonicalization
254 * mode. We don't want to throttle the driver if we're in
255 * canonical mode and don't have a newline yet!
259 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
260 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
262 throttled = tty_throttle_safe(tty);
266 __tty_set_flow_change(tty, 0);
269 static void n_tty_check_unthrottle(struct tty_struct *tty)
271 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
272 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
273 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
278 n_tty_write_wakeup(tty->link);
279 if (waitqueue_active(&tty->link->write_wait))
280 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
284 /* If there is enough space in the read buffer now, let the
285 * low-level driver know. We use chars_in_buffer() to
286 * check the buffer, as it now knows about canonical mode.
287 * Otherwise, if the driver is throttled and the line is
288 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
289 * we won't get any more characters.
294 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
295 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
300 unthrottled = tty_unthrottle_safe(tty);
304 __tty_set_flow_change(tty, 0);
308 * put_tty_queue - add character to tty
312 * Add a character to the tty read_buf queue.
314 * n_tty_receive_buf()/producer path:
315 * caller holds non-exclusive termios_rwsem
318 * read_head is only considered 'published' if canonical mode is
322 static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
324 *read_buf_addr(ldata, ldata->read_head) = c;
329 * reset_buffer_flags - reset buffer state
330 * @tty: terminal to reset
332 * Reset the read buffer counters and clear the flags.
333 * Called from n_tty_open() and n_tty_flush_buffer().
335 * Locking: caller holds exclusive termios_rwsem
336 * (or locking is not required)
339 static void reset_buffer_flags(struct n_tty_data *ldata)
341 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
342 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
343 ldata->echo_mark = 0;
344 ldata->line_start = 0;
347 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
351 static void n_tty_packet_mode_flush(struct tty_struct *tty)
355 if (tty->link->packet) {
356 spin_lock_irqsave(&tty->ctrl_lock, flags);
357 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
358 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
359 if (waitqueue_active(&tty->link->read_wait))
360 wake_up_interruptible(&tty->link->read_wait);
365 * n_tty_flush_buffer - clean input queue
366 * @tty: terminal device
368 * Flush the input buffer. Called when the tty layer wants the
369 * buffer flushed (eg at hangup) or when the N_TTY line discipline
370 * internally has to clean the pending queue (for example some signals).
372 * Holds termios_rwsem to exclude producer/consumer while
373 * buffer indices are reset.
375 * Locking: ctrl_lock, exclusive termios_rwsem
378 static void n_tty_flush_buffer(struct tty_struct *tty)
380 down_write(&tty->termios_rwsem);
381 reset_buffer_flags(tty->disc_data);
385 n_tty_packet_mode_flush(tty);
386 up_write(&tty->termios_rwsem);
390 * n_tty_chars_in_buffer - report available bytes
393 * Report the number of characters buffered to be delivered to user
394 * at this instant in time.
396 * Locking: exclusive termios_rwsem
399 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
403 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
405 down_write(&tty->termios_rwsem);
406 n = chars_in_buffer(tty);
407 up_write(&tty->termios_rwsem);
412 * is_utf8_continuation - utf8 multibyte check
415 * Returns true if the utf8 character 'c' is a multibyte continuation
416 * character. We use this to correctly compute the on screen size
417 * of the character when printing
420 static inline int is_utf8_continuation(unsigned char c)
422 return (c & 0xc0) == 0x80;
426 * is_continuation - multibyte check
429 * Returns true if the utf8 character 'c' is a multibyte continuation
430 * character and the terminal is in unicode mode.
433 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
435 return I_IUTF8(tty) && is_utf8_continuation(c);
439 * do_output_char - output one character
440 * @c: character (or partial unicode symbol)
441 * @tty: terminal device
442 * @space: space available in tty driver write buffer
444 * This is a helper function that handles one output character
445 * (including special characters like TAB, CR, LF, etc.),
446 * doing OPOST processing and putting the results in the
447 * tty driver's write buffer.
449 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
450 * and NLDLY. They simply aren't relevant in the world today.
451 * If you ever need them, add them here.
453 * Returns the number of bytes of buffer space used or -1 if
456 * Locking: should be called under the output_lock to protect
457 * the column state and space left in the buffer
460 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
462 struct n_tty_data *ldata = tty->disc_data;
475 ldata->canon_column = ldata->column = 0;
476 tty->ops->write(tty, "\r\n", 2);
479 ldata->canon_column = ldata->column;
482 if (O_ONOCR(tty) && ldata->column == 0)
487 ldata->canon_column = ldata->column = 0;
490 ldata->canon_column = ldata->column = 0;
493 spaces = 8 - (ldata->column & 7);
494 if (O_TABDLY(tty) == XTABS) {
497 ldata->column += spaces;
498 tty->ops->write(tty, " ", spaces);
501 ldata->column += spaces;
504 if (ldata->column > 0)
511 if (!is_continuation(c, tty))
517 tty_put_char(tty, c);
522 * process_output - output post processor
523 * @c: character (or partial unicode symbol)
524 * @tty: terminal device
526 * Output one character with OPOST processing.
527 * Returns -1 when the output device is full and the character
530 * Locking: output_lock to protect column state and space left
531 * (also, this is called from n_tty_write under the
532 * tty layer write lock)
535 static int process_output(unsigned char c, struct tty_struct *tty)
537 struct n_tty_data *ldata = tty->disc_data;
540 mutex_lock(&ldata->output_lock);
542 space = tty_write_room(tty);
543 retval = do_output_char(c, tty, space);
545 mutex_unlock(&ldata->output_lock);
553 * process_output_block - block post processor
554 * @tty: terminal device
555 * @buf: character buffer
556 * @nr: number of bytes to output
558 * Output a block of characters with OPOST processing.
559 * Returns the number of characters output.
561 * This path is used to speed up block console writes, among other
562 * things when processing blocks of output data. It handles only
563 * the simple cases normally found and helps to generate blocks of
564 * symbols for the console driver and thus improve performance.
566 * Locking: output_lock to protect column state and space left
567 * (also, this is called from n_tty_write under the
568 * tty layer write lock)
571 static ssize_t process_output_block(struct tty_struct *tty,
572 const unsigned char *buf, unsigned int nr)
574 struct n_tty_data *ldata = tty->disc_data;
577 const unsigned char *cp;
579 mutex_lock(&ldata->output_lock);
581 space = tty_write_room(tty);
583 mutex_unlock(&ldata->output_lock);
589 for (i = 0, cp = buf; i < nr; i++, cp++) {
590 unsigned char c = *cp;
598 ldata->canon_column = ldata->column;
601 if (O_ONOCR(tty) && ldata->column == 0)
605 ldata->canon_column = ldata->column = 0;
610 if (ldata->column > 0)
617 if (!is_continuation(c, tty))
624 i = tty->ops->write(tty, buf, i);
626 mutex_unlock(&ldata->output_lock);
631 * process_echoes - write pending echo characters
632 * @tty: terminal device
634 * Write previously buffered echo (and other ldisc-generated)
635 * characters to the tty.
637 * Characters generated by the ldisc (including echoes) need to
638 * be buffered because the driver's write buffer can fill during
639 * heavy program output. Echoing straight to the driver will
640 * often fail under these conditions, causing lost characters and
641 * resulting mismatches of ldisc state information.
643 * Since the ldisc state must represent the characters actually sent
644 * to the driver at the time of the write, operations like certain
645 * changes in column state are also saved in the buffer and executed
648 * A circular fifo buffer is used so that the most recent characters
649 * are prioritized. Also, when control characters are echoed with a
650 * prefixed "^", the pair is treated atomically and thus not separated.
652 * Locking: callers must hold output_lock
655 static size_t __process_echoes(struct tty_struct *tty)
657 struct n_tty_data *ldata = tty->disc_data;
658 int space, old_space;
662 old_space = space = tty_write_room(tty);
664 tail = ldata->echo_tail;
665 while (ldata->echo_commit != tail) {
666 c = echo_buf(ldata, tail);
667 if (c == ECHO_OP_START) {
669 int no_space_left = 0;
672 * If the buffer byte is the start of a multi-byte
673 * operation, get the next byte, which is either the
674 * op code or a control character value.
676 op = echo_buf(ldata, tail + 1);
679 unsigned int num_chars, num_bs;
681 case ECHO_OP_ERASE_TAB:
682 num_chars = echo_buf(ldata, tail + 2);
685 * Determine how many columns to go back
686 * in order to erase the tab.
687 * This depends on the number of columns
688 * used by other characters within the tab
689 * area. If this (modulo 8) count is from
690 * the start of input rather than from a
691 * previous tab, we offset by canon column.
692 * Otherwise, tab spacing is normal.
694 if (!(num_chars & 0x80))
695 num_chars += ldata->canon_column;
696 num_bs = 8 - (num_chars & 7);
698 if (num_bs > space) {
704 tty_put_char(tty, '\b');
705 if (ldata->column > 0)
711 case ECHO_OP_SET_CANON_COL:
712 ldata->canon_column = ldata->column;
716 case ECHO_OP_MOVE_BACK_COL:
717 if (ldata->column > 0)
723 /* This is an escaped echo op start code */
728 tty_put_char(tty, ECHO_OP_START);
736 * If the op is not a special byte code,
737 * it is a ctrl char tagged to be echoed
738 * as "^X" (where X is the letter
739 * representing the control char).
740 * Note that we must ensure there is
741 * enough space for the whole ctrl pair.
748 tty_put_char(tty, '^');
749 tty_put_char(tty, op ^ 0100);
759 int retval = do_output_char(c, tty, space);
766 tty_put_char(tty, c);
773 /* If the echo buffer is nearly full (so that the possibility exists
774 * of echo overrun before the next commit), then discard enough
775 * data at the tail to prevent a subsequent overrun */
776 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
777 if (echo_buf(ldata, tail) == ECHO_OP_START) {
778 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
786 ldata->echo_tail = tail;
787 return old_space - space;
790 static void commit_echoes(struct tty_struct *tty)
792 struct n_tty_data *ldata = tty->disc_data;
793 size_t nr, old, echoed;
796 head = ldata->echo_head;
797 ldata->echo_mark = head;
798 old = ldata->echo_commit - ldata->echo_tail;
800 /* Process committed echoes if the accumulated # of bytes
801 * is over the threshold (and try again each time another
802 * block is accumulated) */
803 nr = head - ldata->echo_tail;
804 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
807 mutex_lock(&ldata->output_lock);
808 ldata->echo_commit = head;
809 echoed = __process_echoes(tty);
810 mutex_unlock(&ldata->output_lock);
812 if (echoed && tty->ops->flush_chars)
813 tty->ops->flush_chars(tty);
816 static void process_echoes(struct tty_struct *tty)
818 struct n_tty_data *ldata = tty->disc_data;
821 if (ldata->echo_mark == ldata->echo_tail)
824 mutex_lock(&ldata->output_lock);
825 ldata->echo_commit = ldata->echo_mark;
826 echoed = __process_echoes(tty);
827 mutex_unlock(&ldata->output_lock);
829 if (echoed && tty->ops->flush_chars)
830 tty->ops->flush_chars(tty);
833 /* NB: echo_mark and echo_head should be equivalent here */
834 static void flush_echoes(struct tty_struct *tty)
836 struct n_tty_data *ldata = tty->disc_data;
838 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
839 ldata->echo_commit == ldata->echo_head)
842 mutex_lock(&ldata->output_lock);
843 ldata->echo_commit = ldata->echo_head;
844 __process_echoes(tty);
845 mutex_unlock(&ldata->output_lock);
849 * add_echo_byte - add a byte to the echo buffer
850 * @c: unicode byte to echo
853 * Add a character or operation byte to the echo buffer.
856 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
858 *echo_buf_addr(ldata, ldata->echo_head++) = c;
862 * echo_move_back_col - add operation to move back a column
865 * Add an operation to the echo buffer to move back one column.
868 static void echo_move_back_col(struct n_tty_data *ldata)
870 add_echo_byte(ECHO_OP_START, ldata);
871 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
875 * echo_set_canon_col - add operation to set the canon column
878 * Add an operation to the echo buffer to set the canon column
879 * to the current column.
882 static void echo_set_canon_col(struct n_tty_data *ldata)
884 add_echo_byte(ECHO_OP_START, ldata);
885 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
889 * echo_erase_tab - add operation to erase a tab
890 * @num_chars: number of character columns already used
891 * @after_tab: true if num_chars starts after a previous tab
894 * Add an operation to the echo buffer to erase a tab.
896 * Called by the eraser function, which knows how many character
897 * columns have been used since either a previous tab or the start
898 * of input. This information will be used later, along with
899 * canon column (if applicable), to go back the correct number
903 static void echo_erase_tab(unsigned int num_chars, int after_tab,
904 struct n_tty_data *ldata)
906 add_echo_byte(ECHO_OP_START, ldata);
907 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
909 /* We only need to know this modulo 8 (tab spacing) */
912 /* Set the high bit as a flag if num_chars is after a previous tab */
916 add_echo_byte(num_chars, ldata);
920 * echo_char_raw - echo a character raw
921 * @c: unicode byte to echo
922 * @tty: terminal device
924 * Echo user input back onto the screen. This must be called only when
925 * L_ECHO(tty) is true. Called from the driver receive_buf path.
927 * This variant does not treat control characters specially.
930 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
932 if (c == ECHO_OP_START) {
933 add_echo_byte(ECHO_OP_START, ldata);
934 add_echo_byte(ECHO_OP_START, ldata);
936 add_echo_byte(c, ldata);
941 * echo_char - echo a character
942 * @c: unicode byte to echo
943 * @tty: terminal device
945 * Echo user input back onto the screen. This must be called only when
946 * L_ECHO(tty) is true. Called from the driver receive_buf path.
948 * This variant tags control characters to be echoed as "^X"
949 * (where X is the letter representing the control char).
952 static void echo_char(unsigned char c, struct tty_struct *tty)
954 struct n_tty_data *ldata = tty->disc_data;
956 if (c == ECHO_OP_START) {
957 add_echo_byte(ECHO_OP_START, ldata);
958 add_echo_byte(ECHO_OP_START, ldata);
960 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
961 add_echo_byte(ECHO_OP_START, ldata);
962 add_echo_byte(c, ldata);
967 * finish_erasing - complete erase
971 static inline void finish_erasing(struct n_tty_data *ldata)
973 if (ldata->erasing) {
974 echo_char_raw('/', ldata);
980 * eraser - handle erase function
981 * @c: character input
982 * @tty: terminal device
984 * Perform erase and necessary output when an erase character is
985 * present in the stream from the driver layer. Handles the complexities
986 * of UTF-8 multibyte symbols.
988 * n_tty_receive_buf()/producer path:
989 * caller holds non-exclusive termios_rwsem
992 * Modifying the read_head is not considered a publish in this context
993 * because canonical mode is active -- only canon_head publishes
996 static void eraser(unsigned char c, struct tty_struct *tty)
998 struct n_tty_data *ldata = tty->disc_data;
999 enum { ERASE, WERASE, KILL } kill_type;
1004 if (ldata->read_head == ldata->canon_head) {
1005 /* process_output('\a', tty); */ /* what do you think? */
1008 if (c == ERASE_CHAR(tty))
1010 else if (c == WERASE_CHAR(tty))
1014 ldata->read_head = ldata->canon_head;
1017 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1018 ldata->read_head = ldata->canon_head;
1019 finish_erasing(ldata);
1020 echo_char(KILL_CHAR(tty), tty);
1021 /* Add a newline if ECHOK is on and ECHOKE is off. */
1023 echo_char_raw('\n', ldata);
1030 while (ldata->read_head != ldata->canon_head) {
1031 head = ldata->read_head;
1033 /* erase a single possibly multibyte character */
1036 c = read_buf(ldata, head);
1037 } while (is_continuation(c, tty) && head != ldata->canon_head);
1039 /* do not partially erase */
1040 if (is_continuation(c, tty))
1043 if (kill_type == WERASE) {
1044 /* Equivalent to BSD's ALTWERASE. */
1045 if (isalnum(c) || c == '_')
1047 else if (seen_alnums)
1050 cnt = ldata->read_head - head;
1051 ldata->read_head = head;
1053 if (L_ECHOPRT(tty)) {
1054 if (!ldata->erasing) {
1055 echo_char_raw('\\', ldata);
1058 /* if cnt > 1, output a multi-byte character */
1062 echo_char_raw(read_buf(ldata, head), ldata);
1063 echo_move_back_col(ldata);
1065 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1066 echo_char(ERASE_CHAR(tty), tty);
1067 } else if (c == '\t') {
1068 unsigned int num_chars = 0;
1070 size_t tail = ldata->read_head;
1073 * Count the columns used for characters
1074 * since the start of input or after a
1076 * This info is used to go back the correct
1077 * number of columns.
1079 while (tail != ldata->canon_head) {
1081 c = read_buf(ldata, tail);
1085 } else if (iscntrl(c)) {
1088 } else if (!is_continuation(c, tty)) {
1092 echo_erase_tab(num_chars, after_tab, ldata);
1094 if (iscntrl(c) && L_ECHOCTL(tty)) {
1095 echo_char_raw('\b', ldata);
1096 echo_char_raw(' ', ldata);
1097 echo_char_raw('\b', ldata);
1099 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1100 echo_char_raw('\b', ldata);
1101 echo_char_raw(' ', ldata);
1102 echo_char_raw('\b', ldata);
1106 if (kill_type == ERASE)
1109 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1110 finish_erasing(ldata);
1114 * isig - handle the ISIG optio
1118 * Called when a signal is being sent due to terminal input.
1119 * Called from the driver receive_buf path so serialized.
1121 * Locking: ctrl_lock
1124 static void isig(int sig, struct tty_struct *tty)
1126 struct pid *tty_pgrp = tty_get_pgrp(tty);
1128 kill_pgrp(tty_pgrp, sig, 1);
1134 * n_tty_receive_break - handle break
1137 * An RS232 break event has been hit in the incoming bitstream. This
1138 * can cause a variety of events depending upon the termios settings.
1140 * n_tty_receive_buf()/producer path:
1141 * caller holds non-exclusive termios_rwsem
1142 * publishes read_head via put_tty_queue()
1144 * Note: may get exclusive termios_rwsem if flushing input buffer
1147 static void n_tty_receive_break(struct tty_struct *tty)
1149 struct n_tty_data *ldata = tty->disc_data;
1153 if (I_BRKINT(tty)) {
1155 if (!L_NOFLSH(tty)) {
1156 /* flushing needs exclusive termios_rwsem */
1157 up_read(&tty->termios_rwsem);
1158 n_tty_flush_buffer(tty);
1159 tty_driver_flush_buffer(tty);
1160 down_read(&tty->termios_rwsem);
1164 if (I_PARMRK(tty)) {
1165 put_tty_queue('\377', ldata);
1166 put_tty_queue('\0', ldata);
1168 put_tty_queue('\0', ldata);
1169 if (waitqueue_active(&tty->read_wait))
1170 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1174 * n_tty_receive_overrun - handle overrun reporting
1177 * Data arrived faster than we could process it. While the tty
1178 * driver has flagged this the bits that were missed are gone
1181 * Called from the receive_buf path so single threaded. Does not
1182 * need locking as num_overrun and overrun_time are function
1186 static void n_tty_receive_overrun(struct tty_struct *tty)
1188 struct n_tty_data *ldata = tty->disc_data;
1191 ldata->num_overrun++;
1192 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1193 time_after(ldata->overrun_time, jiffies)) {
1194 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1196 ldata->num_overrun);
1197 ldata->overrun_time = jiffies;
1198 ldata->num_overrun = 0;
1203 * n_tty_receive_parity_error - error notifier
1204 * @tty: terminal device
1207 * Process a parity error and queue the right data to indicate
1208 * the error case if necessary.
1210 * n_tty_receive_buf()/producer path:
1211 * caller holds non-exclusive termios_rwsem
1212 * publishes read_head via put_tty_queue()
1214 static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1216 struct n_tty_data *ldata = tty->disc_data;
1221 if (I_PARMRK(tty)) {
1222 put_tty_queue('\377', ldata);
1223 put_tty_queue('\0', ldata);
1224 put_tty_queue(c, ldata);
1226 put_tty_queue('\0', ldata);
1228 put_tty_queue(c, ldata);
1229 if (waitqueue_active(&tty->read_wait))
1230 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1234 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1236 if (!L_NOFLSH(tty)) {
1237 /* flushing needs exclusive termios_rwsem */
1238 up_read(&tty->termios_rwsem);
1239 n_tty_flush_buffer(tty);
1240 tty_driver_flush_buffer(tty);
1241 down_read(&tty->termios_rwsem);
1249 process_echoes(tty);
1255 * n_tty_receive_char - perform processing
1256 * @tty: terminal device
1259 * Process an individual character of input received from the driver.
1260 * This is serialized with respect to itself by the rules for the
1263 * n_tty_receive_buf()/producer path:
1264 * caller holds non-exclusive termios_rwsem
1265 * publishes canon_head if canonical mode is active
1266 * otherwise, publishes read_head via put_tty_queue()
1268 * Returns 1 if LNEXT was received, else returns 0
1272 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1274 struct n_tty_data *ldata = tty->disc_data;
1277 if (c == START_CHAR(tty)) {
1279 process_echoes(tty);
1282 if (c == STOP_CHAR(tty)) {
1289 if (c == INTR_CHAR(tty)) {
1290 n_tty_receive_signal_char(tty, SIGINT, c);
1292 } else if (c == QUIT_CHAR(tty)) {
1293 n_tty_receive_signal_char(tty, SIGQUIT, c);
1295 } else if (c == SUSP_CHAR(tty)) {
1296 n_tty_receive_signal_char(tty, SIGTSTP, c);
1301 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1303 process_echoes(tty);
1311 } else if (c == '\n' && I_INLCR(tty))
1314 if (ldata->icanon) {
1315 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1316 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1321 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1324 finish_erasing(ldata);
1325 if (L_ECHOCTL(tty)) {
1326 echo_char_raw('^', ldata);
1327 echo_char_raw('\b', ldata);
1333 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1334 size_t tail = ldata->canon_head;
1336 finish_erasing(ldata);
1338 echo_char_raw('\n', ldata);
1339 while (tail != ldata->read_head) {
1340 echo_char(read_buf(ldata, tail), tty);
1347 if (L_ECHO(tty) || L_ECHONL(tty)) {
1348 echo_char_raw('\n', ldata);
1351 goto handle_newline;
1353 if (c == EOF_CHAR(tty)) {
1354 c = __DISABLED_CHAR;
1355 goto handle_newline;
1357 if ((c == EOL_CHAR(tty)) ||
1358 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1360 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1363 /* Record the column of first canon char. */
1364 if (ldata->canon_head == ldata->read_head)
1365 echo_set_canon_col(ldata);
1370 * XXX does PARMRK doubling happen for
1371 * EOL_CHAR and EOL2_CHAR?
1373 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1374 put_tty_queue(c, ldata);
1377 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1378 put_tty_queue(c, ldata);
1379 ldata->canon_head = ldata->read_head;
1380 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1381 if (waitqueue_active(&tty->read_wait))
1382 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1388 finish_erasing(ldata);
1390 echo_char_raw('\n', ldata);
1392 /* Record the column of first canon char. */
1393 if (ldata->canon_head == ldata->read_head)
1394 echo_set_canon_col(ldata);
1400 /* PARMRK doubling check */
1401 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1402 put_tty_queue(c, ldata);
1404 put_tty_queue(c, ldata);
1409 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1411 struct n_tty_data *ldata = tty->disc_data;
1413 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1415 process_echoes(tty);
1418 finish_erasing(ldata);
1419 /* Record the column of first canon char. */
1420 if (ldata->canon_head == ldata->read_head)
1421 echo_set_canon_col(ldata);
1425 /* PARMRK doubling check */
1426 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1427 put_tty_queue(c, ldata);
1428 put_tty_queue(c, ldata);
1431 static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1433 n_tty_receive_char_inline(tty, c);
1437 n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1439 struct n_tty_data *ldata = tty->disc_data;
1441 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1443 process_echoes(tty);
1446 finish_erasing(ldata);
1447 /* Record the column of first canon char. */
1448 if (ldata->canon_head == ldata->read_head)
1449 echo_set_canon_col(ldata);
1453 put_tty_queue(c, ldata);
1456 static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1460 if (I_IUCLC(tty) && L_IEXTEN(tty))
1464 if (c == STOP_CHAR(tty))
1466 else if (c == START_CHAR(tty) ||
1467 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1468 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1469 c != SUSP_CHAR(tty))) {
1471 process_echoes(tty);
1477 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1483 n_tty_receive_break(tty);
1487 n_tty_receive_parity_error(tty, c);
1490 n_tty_receive_overrun(tty);
1493 printk(KERN_ERR "%s: unknown flag %d\n",
1494 tty_name(tty, buf), flag);
1500 n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1502 struct n_tty_data *ldata = tty->disc_data;
1505 if (likely(flag == TTY_NORMAL)) {
1508 if (I_IUCLC(tty) && L_IEXTEN(tty))
1510 n_tty_receive_char(tty, c);
1512 n_tty_receive_char_flagged(tty, c, flag);
1516 * n_tty_receive_buf - data receive
1517 * @tty: terminal device
1520 * @count: characters
1522 * Called by the terminal driver when a block of characters has
1523 * been received. This function must be called from soft contexts
1524 * not from interrupt context. The driver is responsible for making
1525 * calls one at a time and in order (or using flush_to_ldisc)
1527 * n_tty_receive_buf()/producer path:
1528 * claims non-exclusive termios_rwsem
1529 * publishes read_head and canon_head
1533 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1534 char *fp, int count)
1536 struct n_tty_data *ldata = tty->disc_data;
1539 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1540 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1541 n = min_t(size_t, count, n);
1542 memcpy(read_buf_addr(ldata, head), cp, n);
1543 ldata->read_head += n;
1547 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1548 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1549 n = min_t(size_t, count, n);
1550 memcpy(read_buf_addr(ldata, head), cp, n);
1551 ldata->read_head += n;
1555 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1556 char *fp, int count)
1558 struct n_tty_data *ldata = tty->disc_data;
1559 char flag = TTY_NORMAL;
1564 if (likely(flag == TTY_NORMAL))
1565 put_tty_queue(*cp++, ldata);
1567 n_tty_receive_char_flagged(tty, *cp++, flag);
1572 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1573 char *fp, int count)
1575 char flag = TTY_NORMAL;
1580 if (likely(flag == TTY_NORMAL))
1581 n_tty_receive_char_closing(tty, *cp++);
1583 n_tty_receive_char_flagged(tty, *cp++, flag);
1588 n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1589 char *fp, int count)
1591 struct n_tty_data *ldata = tty->disc_data;
1592 char flag = TTY_NORMAL;
1597 if (likely(flag == TTY_NORMAL)) {
1598 unsigned char c = *cp++;
1602 if (I_IUCLC(tty) && L_IEXTEN(tty))
1604 if (L_EXTPROC(tty)) {
1605 put_tty_queue(c, ldata);
1608 if (!test_bit(c, ldata->char_map))
1609 n_tty_receive_char_inline(tty, c);
1610 else if (n_tty_receive_char_special(tty, c) && count) {
1613 n_tty_receive_char_lnext(tty, *cp++, flag);
1617 n_tty_receive_char_flagged(tty, *cp++, flag);
1622 n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1623 char *fp, int count)
1625 struct n_tty_data *ldata = tty->disc_data;
1626 char flag = TTY_NORMAL;
1631 if (likely(flag == TTY_NORMAL)) {
1632 unsigned char c = *cp++;
1634 if (!test_bit(c, ldata->char_map))
1635 n_tty_receive_char_fast(tty, c);
1636 else if (n_tty_receive_char_special(tty, c) && count) {
1639 n_tty_receive_char_lnext(tty, *cp++, flag);
1643 n_tty_receive_char_flagged(tty, *cp++, flag);
1647 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1648 char *fp, int count)
1650 struct n_tty_data *ldata = tty->disc_data;
1651 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1653 if (ldata->real_raw)
1654 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1655 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1656 n_tty_receive_buf_raw(tty, cp, fp, count);
1657 else if (tty->closing && !L_EXTPROC(tty))
1658 n_tty_receive_buf_closing(tty, cp, fp, count);
1661 char flag = TTY_NORMAL;
1665 n_tty_receive_char_lnext(tty, *cp++, flag);
1669 if (!preops && !I_PARMRK(tty))
1670 n_tty_receive_buf_fast(tty, cp, fp, count);
1672 n_tty_receive_buf_standard(tty, cp, fp, count);
1675 if (tty->ops->flush_chars)
1676 tty->ops->flush_chars(tty);
1679 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1681 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1682 if (waitqueue_active(&tty->read_wait))
1683 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1688 n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1689 char *fp, int count, int flow)
1691 struct n_tty_data *ldata = tty->disc_data;
1692 int room, n, rcvd = 0;
1694 down_read(&tty->termios_rwsem);
1697 room = receive_room(tty);
1698 n = min(count, room);
1704 __receive_buf(tty, cp, fp, n);
1712 tty->receive_room = room;
1713 n_tty_check_throttle(tty);
1714 up_read(&tty->termios_rwsem);
1719 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1720 char *fp, int count)
1722 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1725 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1726 char *fp, int count)
1728 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1731 int is_ignored(int sig)
1733 return (sigismember(¤t->blocked, sig) ||
1734 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1738 * n_tty_set_termios - termios data changed
1740 * @old: previous data
1742 * Called by the tty layer when the user changes termios flags so
1743 * that the line discipline can plan ahead. This function cannot sleep
1744 * and is protected from re-entry by the tty layer. The user is
1745 * guaranteed that this function will not be re-entered or in progress
1746 * when the ldisc is closed.
1748 * Locking: Caller holds tty->termios_rwsem
1751 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1753 struct n_tty_data *ldata = tty->disc_data;
1755 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1756 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1757 ldata->line_start = ldata->read_tail;
1758 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1759 ldata->canon_head = ldata->read_tail;
1762 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1764 ldata->canon_head = ldata->read_head;
1771 ldata->icanon = (L_ICANON(tty) != 0);
1773 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1774 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1775 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1777 bitmap_zero(ldata->char_map, 256);
1779 if (I_IGNCR(tty) || I_ICRNL(tty))
1780 set_bit('\r', ldata->char_map);
1782 set_bit('\n', ldata->char_map);
1784 if (L_ICANON(tty)) {
1785 set_bit(ERASE_CHAR(tty), ldata->char_map);
1786 set_bit(KILL_CHAR(tty), ldata->char_map);
1787 set_bit(EOF_CHAR(tty), ldata->char_map);
1788 set_bit('\n', ldata->char_map);
1789 set_bit(EOL_CHAR(tty), ldata->char_map);
1790 if (L_IEXTEN(tty)) {
1791 set_bit(WERASE_CHAR(tty), ldata->char_map);
1792 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1793 set_bit(EOL2_CHAR(tty), ldata->char_map);
1795 set_bit(REPRINT_CHAR(tty),
1800 set_bit(START_CHAR(tty), ldata->char_map);
1801 set_bit(STOP_CHAR(tty), ldata->char_map);
1804 set_bit(INTR_CHAR(tty), ldata->char_map);
1805 set_bit(QUIT_CHAR(tty), ldata->char_map);
1806 set_bit(SUSP_CHAR(tty), ldata->char_map);
1808 clear_bit(__DISABLED_CHAR, ldata->char_map);
1810 ldata->real_raw = 0;
1813 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1814 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1815 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1816 ldata->real_raw = 1;
1818 ldata->real_raw = 0;
1820 n_tty_set_room(tty);
1822 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1823 * been stopped by STOP_CHAR(tty) before it.
1825 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1827 process_echoes(tty);
1830 /* The termios change make the tty ready for I/O */
1831 if (waitqueue_active(&tty->write_wait))
1832 wake_up_interruptible(&tty->write_wait);
1833 if (waitqueue_active(&tty->read_wait))
1834 wake_up_interruptible(&tty->read_wait);
1838 * n_tty_close - close the ldisc for this tty
1841 * Called from the terminal layer when this line discipline is
1842 * being shut down, either because of a close or becsuse of a
1843 * discipline change. The function will not be called while other
1844 * ldisc methods are in progress.
1847 static void n_tty_close(struct tty_struct *tty)
1849 struct n_tty_data *ldata = tty->disc_data;
1852 n_tty_packet_mode_flush(tty);
1855 tty->disc_data = NULL;
1859 * n_tty_open - open an ldisc
1860 * @tty: terminal to open
1862 * Called when this line discipline is being attached to the
1863 * terminal device. Can sleep. Called serialized so that no
1864 * other events will occur in parallel. No further open will occur
1868 static int n_tty_open(struct tty_struct *tty)
1870 struct n_tty_data *ldata;
1872 /* Currently a malloc failure here can panic */
1873 ldata = vmalloc(sizeof(*ldata));
1877 ldata->overrun_time = jiffies;
1878 mutex_init(&ldata->atomic_read_lock);
1879 mutex_init(&ldata->output_lock);
1881 tty->disc_data = ldata;
1882 reset_buffer_flags(tty->disc_data);
1884 ldata->canon_column = 0;
1885 ldata->minimum_to_wake = 1;
1886 ldata->num_overrun = 0;
1890 /* indicate buffer work may resume */
1891 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1892 n_tty_set_termios(tty, NULL);
1893 tty_unthrottle(tty);
1900 static inline int input_available_p(struct tty_struct *tty, int poll)
1902 struct n_tty_data *ldata = tty->disc_data;
1903 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
1905 if (ldata->icanon && !L_EXTPROC(tty))
1906 return ldata->canon_head != ldata->read_tail;
1908 return read_cnt(ldata) >= amt;
1912 * copy_from_read_buf - copy read data directly
1913 * @tty: terminal device
1917 * Helper function to speed up n_tty_read. It is only called when
1918 * ICANON is off; it copies characters straight from the tty queue to
1919 * user space directly. It can be profitably called twice; once to
1920 * drain the space from the tail pointer to the (physical) end of the
1921 * buffer, and once to drain the space from the (physical) beginning of
1922 * the buffer to head pointer.
1924 * Called under the ldata->atomic_read_lock sem
1926 * n_tty_read()/consumer path:
1927 * caller holds non-exclusive termios_rwsem
1928 * read_tail published
1931 static int copy_from_read_buf(struct tty_struct *tty,
1932 unsigned char __user **b,
1936 struct n_tty_data *ldata = tty->disc_data;
1940 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1943 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1946 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1948 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1949 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1951 ldata->read_tail += n;
1952 /* Turn single EOF into zero-length read */
1953 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1962 * canon_copy_from_read_buf - copy read data in canonical mode
1963 * @tty: terminal device
1967 * Helper function for n_tty_read. It is only called when ICANON is on;
1968 * it copies one line of input up to and including the line-delimiting
1969 * character into the user-space buffer.
1971 * NB: When termios is changed from non-canonical to canonical mode and
1972 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1973 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1974 * This causes data already processed as input to be immediately available
1975 * as input although a newline has not been received.
1977 * Called under the atomic_read_lock mutex
1979 * n_tty_read()/consumer path:
1980 * caller holds non-exclusive termios_rwsem
1981 * read_tail published
1984 static int canon_copy_from_read_buf(struct tty_struct *tty,
1985 unsigned char __user **b,
1988 struct n_tty_data *ldata = tty->disc_data;
1989 size_t n, size, more, c;
1995 /* N.B. avoid overrun if nr == 0 */
1996 n = min(*nr, read_cnt(ldata));
2000 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
2001 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
2003 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2004 __func__, *nr, tail, n, size);
2006 eol = find_next_bit(ldata->read_flags, size, tail);
2007 more = n - (size - tail);
2008 if (eol == N_TTY_BUF_SIZE && more) {
2009 /* scan wrapped without finding set bit */
2010 eol = find_next_bit(ldata->read_flags, more, 0);
2013 } else if (eol != size)
2016 size = N_TTY_BUF_SIZE - tail;
2023 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
2025 eof_push = !n && ldata->read_tail != ldata->line_start;
2028 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2029 __func__, eol, found, n, c, size, more);
2032 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2035 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2037 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2045 clear_bit(eol, ldata->read_flags);
2046 smp_mb__after_atomic();
2047 ldata->read_tail += c;
2051 ldata->line_start = ldata->read_tail;
2054 tty_audit_push(tty);
2056 return eof_push ? -EAGAIN : 0;
2059 extern ssize_t redirected_tty_write(struct file *, const char __user *,
2063 * job_control - check job control
2065 * @file: file handle
2067 * Perform job control management checks on this file/tty descriptor
2068 * and if appropriate send any needed signals and return a negative
2069 * error code if action should be taken.
2071 * Locking: redirected write test is safe
2072 * current->signal->tty check is safe
2073 * ctrl_lock to safely reference tty->pgrp
2076 static int job_control(struct tty_struct *tty, struct file *file)
2078 /* Job control check -- must be done at start and after
2079 every sleep (POSIX.1 7.1.1.4). */
2080 /* NOTE: not yet done after every sleep pending a thorough
2081 check of the logic of this change. -- jlc */
2082 /* don't stop on /dev/console */
2083 if (file->f_op->write == redirected_tty_write ||
2084 current->signal->tty != tty)
2087 spin_lock_irq(&tty->ctrl_lock);
2089 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2090 else if (task_pgrp(current) != tty->pgrp) {
2091 spin_unlock_irq(&tty->ctrl_lock);
2092 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2094 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2095 set_thread_flag(TIF_SIGPENDING);
2096 return -ERESTARTSYS;
2098 spin_unlock_irq(&tty->ctrl_lock);
2104 * n_tty_read - read function for tty
2106 * @file: file object
2107 * @buf: userspace buffer pointer
2110 * Perform reads for the line discipline. We are guaranteed that the
2111 * line discipline will not be closed under us but we may get multiple
2112 * parallel readers and must handle this ourselves. We may also get
2113 * a hangup. Always called in user context, may sleep.
2115 * This code must be sure never to sleep through a hangup.
2117 * n_tty_read()/consumer path:
2118 * claims non-exclusive termios_rwsem
2119 * publishes read_tail
2122 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2123 unsigned char __user *buf, size_t nr)
2125 struct n_tty_data *ldata = tty->disc_data;
2126 unsigned char __user *b = buf;
2127 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2134 c = job_control(tty, file);
2139 * Internal serialization of reads.
2141 if (file->f_flags & O_NONBLOCK) {
2142 if (!mutex_trylock(&ldata->atomic_read_lock))
2145 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2146 return -ERESTARTSYS;
2149 down_read(&tty->termios_rwsem);
2152 timeout = MAX_SCHEDULE_TIMEOUT;
2153 if (!ldata->icanon) {
2154 minimum = MIN_CHAR(tty);
2156 time = (HZ / 10) * TIME_CHAR(tty);
2158 ldata->minimum_to_wake = 1;
2159 else if (!waitqueue_active(&tty->read_wait) ||
2160 (ldata->minimum_to_wake > minimum))
2161 ldata->minimum_to_wake = minimum;
2163 timeout = (HZ / 10) * TIME_CHAR(tty);
2164 ldata->minimum_to_wake = minimum = 1;
2168 packet = tty->packet;
2170 add_wait_queue(&tty->read_wait, &wait);
2172 /* First test for status change. */
2173 if (packet && tty->link->ctrl_status) {
2177 spin_lock_irq(&tty->link->ctrl_lock);
2178 cs = tty->link->ctrl_status;
2179 tty->link->ctrl_status = 0;
2180 spin_unlock_irq(&tty->link->ctrl_lock);
2181 if (tty_put_user(tty, cs, b++)) {
2190 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2191 ((minimum - (b - buf)) >= 1))
2192 ldata->minimum_to_wake = (minimum - (b - buf));
2194 if (!input_available_p(tty, 0)) {
2195 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2199 if (tty_hung_up_p(file))
2203 if (file->f_flags & O_NONBLOCK) {
2207 if (signal_pending(current)) {
2208 retval = -ERESTARTSYS;
2211 n_tty_set_room(tty);
2212 up_read(&tty->termios_rwsem);
2214 timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
2217 down_read(&tty->termios_rwsem);
2221 if (ldata->icanon && !L_EXTPROC(tty)) {
2222 retval = canon_copy_from_read_buf(tty, &b, &nr);
2223 if (retval == -EAGAIN) {
2231 /* Deal with packet mode. */
2232 if (packet && b == buf) {
2233 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2241 uncopied = copy_from_read_buf(tty, &b, &nr);
2242 uncopied += copy_from_read_buf(tty, &b, &nr);
2249 n_tty_check_unthrottle(tty);
2251 if (b - buf >= minimum)
2256 n_tty_set_room(tty);
2257 up_read(&tty->termios_rwsem);
2259 remove_wait_queue(&tty->read_wait, &wait);
2260 if (!waitqueue_active(&tty->read_wait))
2261 ldata->minimum_to_wake = minimum;
2263 mutex_unlock(&ldata->atomic_read_lock);
2272 * n_tty_write - write function for tty
2274 * @file: file object
2275 * @buf: userspace buffer pointer
2278 * Write function of the terminal device. This is serialized with
2279 * respect to other write callers but not to termios changes, reads
2280 * and other such events. Since the receive code will echo characters,
2281 * thus calling driver write methods, the output_lock is used in
2282 * the output processing functions called here as well as in the
2283 * echo processing function to protect the column state and space
2284 * left in the buffer.
2286 * This code must be sure never to sleep through a hangup.
2288 * Locking: output_lock to protect column state and space left
2289 * (note that the process_output*() functions take this
2293 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2294 const unsigned char *buf, size_t nr)
2296 const unsigned char *b = buf;
2297 DEFINE_WAIT_FUNC(wait, woken_wake_function);
2301 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2302 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2303 retval = tty_check_change(tty);
2308 down_read(&tty->termios_rwsem);
2310 /* Write out any echoed characters that are still pending */
2311 process_echoes(tty);
2313 add_wait_queue(&tty->write_wait, &wait);
2315 if (signal_pending(current)) {
2316 retval = -ERESTARTSYS;
2319 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2325 ssize_t num = process_output_block(tty, b, nr);
2337 if (process_output(c, tty) < 0)
2341 if (tty->ops->flush_chars)
2342 tty->ops->flush_chars(tty);
2344 struct n_tty_data *ldata = tty->disc_data;
2347 mutex_lock(&ldata->output_lock);
2348 c = tty->ops->write(tty, b, nr);
2349 mutex_unlock(&ldata->output_lock);
2362 if (file->f_flags & O_NONBLOCK) {
2366 up_read(&tty->termios_rwsem);
2368 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
2370 down_read(&tty->termios_rwsem);
2373 remove_wait_queue(&tty->write_wait, &wait);
2374 if (b - buf != nr && tty->fasync)
2375 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2376 up_read(&tty->termios_rwsem);
2377 return (b - buf) ? b - buf : retval;
2381 * n_tty_poll - poll method for N_TTY
2382 * @tty: terminal device
2383 * @file: file accessing it
2386 * Called when the line discipline is asked to poll() for data or
2387 * for special events. This code is not serialized with respect to
2388 * other events save open/close.
2390 * This code must be sure never to sleep through a hangup.
2391 * Called without the kernel lock held - fine
2394 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2397 struct n_tty_data *ldata = tty->disc_data;
2398 unsigned int mask = 0;
2400 poll_wait(file, &tty->read_wait, wait);
2401 poll_wait(file, &tty->write_wait, wait);
2402 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2404 if (input_available_p(tty, 1))
2405 mask |= POLLIN | POLLRDNORM;
2406 else if (mask & POLLHUP) {
2407 tty_flush_to_ldisc(tty);
2408 if (input_available_p(tty, 1))
2409 mask |= POLLIN | POLLRDNORM;
2411 if (tty->packet && tty->link->ctrl_status)
2412 mask |= POLLPRI | POLLIN | POLLRDNORM;
2413 if (tty_hung_up_p(file))
2415 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2416 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2417 ldata->minimum_to_wake = MIN_CHAR(tty);
2419 ldata->minimum_to_wake = 1;
2421 if (tty->ops->write && !tty_is_writelocked(tty) &&
2422 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2423 tty_write_room(tty) > 0)
2424 mask |= POLLOUT | POLLWRNORM;
2428 static unsigned long inq_canon(struct n_tty_data *ldata)
2430 size_t nr, head, tail;
2432 if (ldata->canon_head == ldata->read_tail)
2434 head = ldata->canon_head;
2435 tail = ldata->read_tail;
2437 /* Skip EOF-chars.. */
2438 while (head != tail) {
2439 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2440 read_buf(ldata, tail) == __DISABLED_CHAR)
2447 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2448 unsigned int cmd, unsigned long arg)
2450 struct n_tty_data *ldata = tty->disc_data;
2455 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2457 down_write(&tty->termios_rwsem);
2459 retval = inq_canon(ldata);
2461 retval = read_cnt(ldata);
2462 up_write(&tty->termios_rwsem);
2463 return put_user(retval, (unsigned int __user *) arg);
2465 return n_tty_ioctl_helper(tty, file, cmd, arg);
2469 static void n_tty_fasync(struct tty_struct *tty, int on)
2471 struct n_tty_data *ldata = tty->disc_data;
2473 if (!waitqueue_active(&tty->read_wait)) {
2475 ldata->minimum_to_wake = 1;
2476 else if (!tty->fasync)
2477 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2481 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2482 .magic = TTY_LDISC_MAGIC,
2485 .close = n_tty_close,
2486 .flush_buffer = n_tty_flush_buffer,
2487 .chars_in_buffer = n_tty_chars_in_buffer,
2489 .write = n_tty_write,
2490 .ioctl = n_tty_ioctl,
2491 .set_termios = n_tty_set_termios,
2493 .receive_buf = n_tty_receive_buf,
2494 .write_wakeup = n_tty_write_wakeup,
2495 .fasync = n_tty_fasync,
2496 .receive_buf2 = n_tty_receive_buf2,
2500 * n_tty_inherit_ops - inherit N_TTY methods
2501 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2503 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2507 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2509 *ops = tty_ldisc_N_TTY;
2511 ops->refcount = ops->flags = 0;
2513 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);