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;
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->echo_mark = 0;
343 ldata->line_start = 0;
346 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
350 static void n_tty_packet_mode_flush(struct tty_struct *tty)
354 spin_lock_irqsave(&tty->ctrl_lock, flags);
355 if (tty->link->packet) {
356 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
357 if (waitqueue_active(&tty->link->read_wait))
358 wake_up_interruptible(&tty->link->read_wait);
360 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
364 * n_tty_flush_buffer - clean input queue
365 * @tty: terminal device
367 * Flush the input buffer. Called when the tty layer wants the
368 * buffer flushed (eg at hangup) or when the N_TTY line discipline
369 * internally has to clean the pending queue (for example some signals).
371 * Holds termios_rwsem to exclude producer/consumer while
372 * buffer indices are reset.
374 * Locking: ctrl_lock, exclusive termios_rwsem
377 static void n_tty_flush_buffer(struct tty_struct *tty)
379 down_write(&tty->termios_rwsem);
380 reset_buffer_flags(tty->disc_data);
384 n_tty_packet_mode_flush(tty);
385 up_write(&tty->termios_rwsem);
389 * n_tty_chars_in_buffer - report available bytes
392 * Report the number of characters buffered to be delivered to user
393 * at this instant in time.
395 * Locking: exclusive termios_rwsem
398 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
402 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
404 down_write(&tty->termios_rwsem);
405 n = chars_in_buffer(tty);
406 up_write(&tty->termios_rwsem);
411 * is_utf8_continuation - utf8 multibyte check
414 * Returns true if the utf8 character 'c' is a multibyte continuation
415 * character. We use this to correctly compute the on screen size
416 * of the character when printing
419 static inline int is_utf8_continuation(unsigned char c)
421 return (c & 0xc0) == 0x80;
425 * is_continuation - multibyte check
428 * Returns true if the utf8 character 'c' is a multibyte continuation
429 * character and the terminal is in unicode mode.
432 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
434 return I_IUTF8(tty) && is_utf8_continuation(c);
438 * do_output_char - output one character
439 * @c: character (or partial unicode symbol)
440 * @tty: terminal device
441 * @space: space available in tty driver write buffer
443 * This is a helper function that handles one output character
444 * (including special characters like TAB, CR, LF, etc.),
445 * doing OPOST processing and putting the results in the
446 * tty driver's write buffer.
448 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
449 * and NLDLY. They simply aren't relevant in the world today.
450 * If you ever need them, add them here.
452 * Returns the number of bytes of buffer space used or -1 if
455 * Locking: should be called under the output_lock to protect
456 * the column state and space left in the buffer
459 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
461 struct n_tty_data *ldata = tty->disc_data;
474 ldata->canon_column = ldata->column = 0;
475 tty->ops->write(tty, "\r\n", 2);
478 ldata->canon_column = ldata->column;
481 if (O_ONOCR(tty) && ldata->column == 0)
486 ldata->canon_column = ldata->column = 0;
489 ldata->canon_column = ldata->column = 0;
492 spaces = 8 - (ldata->column & 7);
493 if (O_TABDLY(tty) == XTABS) {
496 ldata->column += spaces;
497 tty->ops->write(tty, " ", spaces);
500 ldata->column += spaces;
503 if (ldata->column > 0)
510 if (!is_continuation(c, tty))
516 tty_put_char(tty, c);
521 * process_output - output post processor
522 * @c: character (or partial unicode symbol)
523 * @tty: terminal device
525 * Output one character with OPOST processing.
526 * Returns -1 when the output device is full and the character
529 * Locking: output_lock to protect column state and space left
530 * (also, this is called from n_tty_write under the
531 * tty layer write lock)
534 static int process_output(unsigned char c, struct tty_struct *tty)
536 struct n_tty_data *ldata = tty->disc_data;
539 mutex_lock(&ldata->output_lock);
541 space = tty_write_room(tty);
542 retval = do_output_char(c, tty, space);
544 mutex_unlock(&ldata->output_lock);
552 * process_output_block - block post processor
553 * @tty: terminal device
554 * @buf: character buffer
555 * @nr: number of bytes to output
557 * Output a block of characters with OPOST processing.
558 * Returns the number of characters output.
560 * This path is used to speed up block console writes, among other
561 * things when processing blocks of output data. It handles only
562 * the simple cases normally found and helps to generate blocks of
563 * symbols for the console driver and thus improve performance.
565 * Locking: output_lock to protect column state and space left
566 * (also, this is called from n_tty_write under the
567 * tty layer write lock)
570 static ssize_t process_output_block(struct tty_struct *tty,
571 const unsigned char *buf, unsigned int nr)
573 struct n_tty_data *ldata = tty->disc_data;
576 const unsigned char *cp;
578 mutex_lock(&ldata->output_lock);
580 space = tty_write_room(tty);
582 mutex_unlock(&ldata->output_lock);
588 for (i = 0, cp = buf; i < nr; i++, cp++) {
589 unsigned char c = *cp;
597 ldata->canon_column = ldata->column;
600 if (O_ONOCR(tty) && ldata->column == 0)
604 ldata->canon_column = ldata->column = 0;
609 if (ldata->column > 0)
616 if (!is_continuation(c, tty))
623 i = tty->ops->write(tty, buf, i);
625 mutex_unlock(&ldata->output_lock);
630 * process_echoes - write pending echo characters
631 * @tty: terminal device
633 * Write previously buffered echo (and other ldisc-generated)
634 * characters to the tty.
636 * Characters generated by the ldisc (including echoes) need to
637 * be buffered because the driver's write buffer can fill during
638 * heavy program output. Echoing straight to the driver will
639 * often fail under these conditions, causing lost characters and
640 * resulting mismatches of ldisc state information.
642 * Since the ldisc state must represent the characters actually sent
643 * to the driver at the time of the write, operations like certain
644 * changes in column state are also saved in the buffer and executed
647 * A circular fifo buffer is used so that the most recent characters
648 * are prioritized. Also, when control characters are echoed with a
649 * prefixed "^", the pair is treated atomically and thus not separated.
651 * Locking: callers must hold output_lock
654 static size_t __process_echoes(struct tty_struct *tty)
656 struct n_tty_data *ldata = tty->disc_data;
657 int space, old_space;
661 old_space = space = tty_write_room(tty);
663 tail = ldata->echo_tail;
664 while (ldata->echo_commit != tail) {
665 c = echo_buf(ldata, tail);
666 if (c == ECHO_OP_START) {
668 int no_space_left = 0;
671 * If the buffer byte is the start of a multi-byte
672 * operation, get the next byte, which is either the
673 * op code or a control character value.
675 op = echo_buf(ldata, tail + 1);
678 unsigned int num_chars, num_bs;
680 case ECHO_OP_ERASE_TAB:
681 num_chars = echo_buf(ldata, tail + 2);
684 * Determine how many columns to go back
685 * in order to erase the tab.
686 * This depends on the number of columns
687 * used by other characters within the tab
688 * area. If this (modulo 8) count is from
689 * the start of input rather than from a
690 * previous tab, we offset by canon column.
691 * Otherwise, tab spacing is normal.
693 if (!(num_chars & 0x80))
694 num_chars += ldata->canon_column;
695 num_bs = 8 - (num_chars & 7);
697 if (num_bs > space) {
703 tty_put_char(tty, '\b');
704 if (ldata->column > 0)
710 case ECHO_OP_SET_CANON_COL:
711 ldata->canon_column = ldata->column;
715 case ECHO_OP_MOVE_BACK_COL:
716 if (ldata->column > 0)
722 /* This is an escaped echo op start code */
727 tty_put_char(tty, ECHO_OP_START);
735 * If the op is not a special byte code,
736 * it is a ctrl char tagged to be echoed
737 * as "^X" (where X is the letter
738 * representing the control char).
739 * Note that we must ensure there is
740 * enough space for the whole ctrl pair.
747 tty_put_char(tty, '^');
748 tty_put_char(tty, op ^ 0100);
758 int retval = do_output_char(c, tty, space);
765 tty_put_char(tty, c);
772 /* If the echo buffer is nearly full (so that the possibility exists
773 * of echo overrun before the next commit), then discard enough
774 * data at the tail to prevent a subsequent overrun */
775 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
776 if (echo_buf(ldata, tail) == ECHO_OP_START) {
777 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
785 ldata->echo_tail = tail;
786 return old_space - space;
789 static void commit_echoes(struct tty_struct *tty)
791 struct n_tty_data *ldata = tty->disc_data;
792 size_t nr, old, echoed;
795 head = ldata->echo_head;
796 ldata->echo_mark = head;
797 old = ldata->echo_commit - ldata->echo_tail;
799 /* Process committed echoes if the accumulated # of bytes
800 * is over the threshold (and try again each time another
801 * block is accumulated) */
802 nr = head - ldata->echo_tail;
803 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
806 mutex_lock(&ldata->output_lock);
807 ldata->echo_commit = head;
808 echoed = __process_echoes(tty);
809 mutex_unlock(&ldata->output_lock);
811 if (echoed && tty->ops->flush_chars)
812 tty->ops->flush_chars(tty);
815 static void process_echoes(struct tty_struct *tty)
817 struct n_tty_data *ldata = tty->disc_data;
820 if (ldata->echo_mark == ldata->echo_tail)
823 mutex_lock(&ldata->output_lock);
824 ldata->echo_commit = ldata->echo_mark;
825 echoed = __process_echoes(tty);
826 mutex_unlock(&ldata->output_lock);
828 if (echoed && tty->ops->flush_chars)
829 tty->ops->flush_chars(tty);
832 /* NB: echo_mark and echo_head should be equivalent here */
833 static void flush_echoes(struct tty_struct *tty)
835 struct n_tty_data *ldata = tty->disc_data;
837 if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
838 ldata->echo_commit == ldata->echo_head)
841 mutex_lock(&ldata->output_lock);
842 ldata->echo_commit = ldata->echo_head;
843 __process_echoes(tty);
844 mutex_unlock(&ldata->output_lock);
848 * add_echo_byte - add a byte to the echo buffer
849 * @c: unicode byte to echo
852 * Add a character or operation byte to the echo buffer.
855 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
857 *echo_buf_addr(ldata, ldata->echo_head++) = c;
861 * echo_move_back_col - add operation to move back a column
864 * Add an operation to the echo buffer to move back one column.
867 static void echo_move_back_col(struct n_tty_data *ldata)
869 add_echo_byte(ECHO_OP_START, ldata);
870 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
874 * echo_set_canon_col - add operation to set the canon column
877 * Add an operation to the echo buffer to set the canon column
878 * to the current column.
881 static void echo_set_canon_col(struct n_tty_data *ldata)
883 add_echo_byte(ECHO_OP_START, ldata);
884 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
888 * echo_erase_tab - add operation to erase a tab
889 * @num_chars: number of character columns already used
890 * @after_tab: true if num_chars starts after a previous tab
893 * Add an operation to the echo buffer to erase a tab.
895 * Called by the eraser function, which knows how many character
896 * columns have been used since either a previous tab or the start
897 * of input. This information will be used later, along with
898 * canon column (if applicable), to go back the correct number
902 static void echo_erase_tab(unsigned int num_chars, int after_tab,
903 struct n_tty_data *ldata)
905 add_echo_byte(ECHO_OP_START, ldata);
906 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
908 /* We only need to know this modulo 8 (tab spacing) */
911 /* Set the high bit as a flag if num_chars is after a previous tab */
915 add_echo_byte(num_chars, ldata);
919 * echo_char_raw - echo a character raw
920 * @c: unicode byte to echo
921 * @tty: terminal device
923 * Echo user input back onto the screen. This must be called only when
924 * L_ECHO(tty) is true. Called from the driver receive_buf path.
926 * This variant does not treat control characters specially.
929 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
931 if (c == ECHO_OP_START) {
932 add_echo_byte(ECHO_OP_START, ldata);
933 add_echo_byte(ECHO_OP_START, ldata);
935 add_echo_byte(c, ldata);
940 * echo_char - echo a character
941 * @c: unicode byte to echo
942 * @tty: terminal device
944 * Echo user input back onto the screen. This must be called only when
945 * L_ECHO(tty) is true. Called from the driver receive_buf path.
947 * This variant tags control characters to be echoed as "^X"
948 * (where X is the letter representing the control char).
951 static void echo_char(unsigned char c, struct tty_struct *tty)
953 struct n_tty_data *ldata = tty->disc_data;
955 if (c == ECHO_OP_START) {
956 add_echo_byte(ECHO_OP_START, ldata);
957 add_echo_byte(ECHO_OP_START, ldata);
959 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
960 add_echo_byte(ECHO_OP_START, ldata);
961 add_echo_byte(c, ldata);
966 * finish_erasing - complete erase
970 static inline void finish_erasing(struct n_tty_data *ldata)
972 if (ldata->erasing) {
973 echo_char_raw('/', ldata);
979 * eraser - handle erase function
980 * @c: character input
981 * @tty: terminal device
983 * Perform erase and necessary output when an erase character is
984 * present in the stream from the driver layer. Handles the complexities
985 * of UTF-8 multibyte symbols.
987 * n_tty_receive_buf()/producer path:
988 * caller holds non-exclusive termios_rwsem
991 * Modifying the read_head is not considered a publish in this context
992 * because canonical mode is active -- only canon_head publishes
995 static void eraser(unsigned char c, struct tty_struct *tty)
997 struct n_tty_data *ldata = tty->disc_data;
998 enum { ERASE, WERASE, KILL } kill_type;
1003 if (ldata->read_head == ldata->canon_head) {
1004 /* process_output('\a', tty); */ /* what do you think? */
1007 if (c == ERASE_CHAR(tty))
1009 else if (c == WERASE_CHAR(tty))
1013 ldata->read_head = ldata->canon_head;
1016 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1017 ldata->read_head = ldata->canon_head;
1018 finish_erasing(ldata);
1019 echo_char(KILL_CHAR(tty), tty);
1020 /* Add a newline if ECHOK is on and ECHOKE is off. */
1022 echo_char_raw('\n', ldata);
1029 while (ldata->read_head != ldata->canon_head) {
1030 head = ldata->read_head;
1032 /* erase a single possibly multibyte character */
1035 c = read_buf(ldata, head);
1036 } while (is_continuation(c, tty) && head != ldata->canon_head);
1038 /* do not partially erase */
1039 if (is_continuation(c, tty))
1042 if (kill_type == WERASE) {
1043 /* Equivalent to BSD's ALTWERASE. */
1044 if (isalnum(c) || c == '_')
1046 else if (seen_alnums)
1049 cnt = ldata->read_head - head;
1050 ldata->read_head = head;
1052 if (L_ECHOPRT(tty)) {
1053 if (!ldata->erasing) {
1054 echo_char_raw('\\', ldata);
1057 /* if cnt > 1, output a multi-byte character */
1061 echo_char_raw(read_buf(ldata, head), ldata);
1062 echo_move_back_col(ldata);
1064 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1065 echo_char(ERASE_CHAR(tty), tty);
1066 } else if (c == '\t') {
1067 unsigned int num_chars = 0;
1069 size_t tail = ldata->read_head;
1072 * Count the columns used for characters
1073 * since the start of input or after a
1075 * This info is used to go back the correct
1076 * number of columns.
1078 while (tail != ldata->canon_head) {
1080 c = read_buf(ldata, tail);
1084 } else if (iscntrl(c)) {
1087 } else if (!is_continuation(c, tty)) {
1091 echo_erase_tab(num_chars, after_tab, ldata);
1093 if (iscntrl(c) && L_ECHOCTL(tty)) {
1094 echo_char_raw('\b', ldata);
1095 echo_char_raw(' ', ldata);
1096 echo_char_raw('\b', ldata);
1098 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1099 echo_char_raw('\b', ldata);
1100 echo_char_raw(' ', ldata);
1101 echo_char_raw('\b', ldata);
1105 if (kill_type == ERASE)
1108 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1109 finish_erasing(ldata);
1113 * isig - handle the ISIG optio
1117 * Called when a signal is being sent due to terminal input.
1118 * Called from the driver receive_buf path so serialized.
1120 * Locking: ctrl_lock
1123 static void isig(int sig, struct tty_struct *tty)
1125 struct pid *tty_pgrp = tty_get_pgrp(tty);
1127 kill_pgrp(tty_pgrp, sig, 1);
1133 * n_tty_receive_break - handle break
1136 * An RS232 break event has been hit in the incoming bitstream. This
1137 * can cause a variety of events depending upon the termios settings.
1139 * n_tty_receive_buf()/producer path:
1140 * caller holds non-exclusive termios_rwsem
1141 * publishes read_head via put_tty_queue()
1143 * Note: may get exclusive termios_rwsem if flushing input buffer
1146 static void n_tty_receive_break(struct tty_struct *tty)
1148 struct n_tty_data *ldata = tty->disc_data;
1152 if (I_BRKINT(tty)) {
1154 if (!L_NOFLSH(tty)) {
1155 /* flushing needs exclusive termios_rwsem */
1156 up_read(&tty->termios_rwsem);
1157 n_tty_flush_buffer(tty);
1158 tty_driver_flush_buffer(tty);
1159 down_read(&tty->termios_rwsem);
1163 if (I_PARMRK(tty)) {
1164 put_tty_queue('\377', ldata);
1165 put_tty_queue('\0', ldata);
1167 put_tty_queue('\0', ldata);
1168 if (waitqueue_active(&tty->read_wait))
1169 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1173 * n_tty_receive_overrun - handle overrun reporting
1176 * Data arrived faster than we could process it. While the tty
1177 * driver has flagged this the bits that were missed are gone
1180 * Called from the receive_buf path so single threaded. Does not
1181 * need locking as num_overrun and overrun_time are function
1185 static void n_tty_receive_overrun(struct tty_struct *tty)
1187 struct n_tty_data *ldata = tty->disc_data;
1190 ldata->num_overrun++;
1191 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1192 time_after(ldata->overrun_time, jiffies)) {
1193 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1195 ldata->num_overrun);
1196 ldata->overrun_time = jiffies;
1197 ldata->num_overrun = 0;
1202 * n_tty_receive_parity_error - error notifier
1203 * @tty: terminal device
1206 * Process a parity error and queue the right data to indicate
1207 * the error case if necessary.
1209 * n_tty_receive_buf()/producer path:
1210 * caller holds non-exclusive termios_rwsem
1211 * publishes read_head via put_tty_queue()
1213 static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1215 struct n_tty_data *ldata = tty->disc_data;
1220 if (I_PARMRK(tty)) {
1221 put_tty_queue('\377', ldata);
1222 put_tty_queue('\0', ldata);
1223 put_tty_queue(c, ldata);
1225 put_tty_queue('\0', ldata);
1227 put_tty_queue(c, ldata);
1228 if (waitqueue_active(&tty->read_wait))
1229 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1233 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1235 if (!L_NOFLSH(tty)) {
1236 /* flushing needs exclusive termios_rwsem */
1237 up_read(&tty->termios_rwsem);
1238 n_tty_flush_buffer(tty);
1239 tty_driver_flush_buffer(tty);
1240 down_read(&tty->termios_rwsem);
1248 process_echoes(tty);
1254 * n_tty_receive_char - perform processing
1255 * @tty: terminal device
1258 * Process an individual character of input received from the driver.
1259 * This is serialized with respect to itself by the rules for the
1262 * n_tty_receive_buf()/producer path:
1263 * caller holds non-exclusive termios_rwsem
1264 * publishes canon_head if canonical mode is active
1265 * otherwise, publishes read_head via put_tty_queue()
1267 * Returns 1 if LNEXT was received, else returns 0
1271 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1273 struct n_tty_data *ldata = tty->disc_data;
1276 if (c == START_CHAR(tty)) {
1278 process_echoes(tty);
1281 if (c == STOP_CHAR(tty)) {
1288 if (c == INTR_CHAR(tty)) {
1289 n_tty_receive_signal_char(tty, SIGINT, c);
1291 } else if (c == QUIT_CHAR(tty)) {
1292 n_tty_receive_signal_char(tty, SIGQUIT, c);
1294 } else if (c == SUSP_CHAR(tty)) {
1295 n_tty_receive_signal_char(tty, SIGTSTP, c);
1300 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1302 process_echoes(tty);
1310 } else if (c == '\n' && I_INLCR(tty))
1313 if (ldata->icanon) {
1314 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1315 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1320 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1323 finish_erasing(ldata);
1324 if (L_ECHOCTL(tty)) {
1325 echo_char_raw('^', ldata);
1326 echo_char_raw('\b', ldata);
1332 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1333 size_t tail = ldata->canon_head;
1335 finish_erasing(ldata);
1337 echo_char_raw('\n', ldata);
1338 while (tail != ldata->read_head) {
1339 echo_char(read_buf(ldata, tail), tty);
1346 if (L_ECHO(tty) || L_ECHONL(tty)) {
1347 echo_char_raw('\n', ldata);
1350 goto handle_newline;
1352 if (c == EOF_CHAR(tty)) {
1353 c = __DISABLED_CHAR;
1354 goto handle_newline;
1356 if ((c == EOL_CHAR(tty)) ||
1357 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1359 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1362 /* Record the column of first canon char. */
1363 if (ldata->canon_head == ldata->read_head)
1364 echo_set_canon_col(ldata);
1369 * XXX does PARMRK doubling happen for
1370 * EOL_CHAR and EOL2_CHAR?
1372 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1373 put_tty_queue(c, ldata);
1376 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1377 put_tty_queue(c, ldata);
1378 ldata->canon_head = ldata->read_head;
1379 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1380 if (waitqueue_active(&tty->read_wait))
1381 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1387 finish_erasing(ldata);
1389 echo_char_raw('\n', ldata);
1391 /* Record the column of first canon char. */
1392 if (ldata->canon_head == ldata->read_head)
1393 echo_set_canon_col(ldata);
1399 /* PARMRK doubling check */
1400 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1401 put_tty_queue(c, ldata);
1403 put_tty_queue(c, ldata);
1408 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1410 struct n_tty_data *ldata = tty->disc_data;
1412 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1414 process_echoes(tty);
1417 finish_erasing(ldata);
1418 /* Record the column of first canon char. */
1419 if (ldata->canon_head == ldata->read_head)
1420 echo_set_canon_col(ldata);
1424 /* PARMRK doubling check */
1425 if (c == (unsigned char) '\377' && I_PARMRK(tty))
1426 put_tty_queue(c, ldata);
1427 put_tty_queue(c, ldata);
1430 static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1432 n_tty_receive_char_inline(tty, c);
1436 n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1438 struct n_tty_data *ldata = tty->disc_data;
1440 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1442 process_echoes(tty);
1445 finish_erasing(ldata);
1446 /* Record the column of first canon char. */
1447 if (ldata->canon_head == ldata->read_head)
1448 echo_set_canon_col(ldata);
1452 put_tty_queue(c, ldata);
1455 static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1459 if (I_IUCLC(tty) && L_IEXTEN(tty))
1463 if (c == STOP_CHAR(tty))
1465 else if (c == START_CHAR(tty) ||
1466 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1467 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1468 c != SUSP_CHAR(tty))) {
1470 process_echoes(tty);
1476 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1482 n_tty_receive_break(tty);
1486 n_tty_receive_parity_error(tty, c);
1489 n_tty_receive_overrun(tty);
1492 printk(KERN_ERR "%s: unknown flag %d\n",
1493 tty_name(tty, buf), flag);
1499 n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1501 struct n_tty_data *ldata = tty->disc_data;
1504 if (likely(flag == TTY_NORMAL)) {
1507 if (I_IUCLC(tty) && L_IEXTEN(tty))
1509 n_tty_receive_char(tty, c);
1511 n_tty_receive_char_flagged(tty, c, flag);
1515 * n_tty_receive_buf - data receive
1516 * @tty: terminal device
1519 * @count: characters
1521 * Called by the terminal driver when a block of characters has
1522 * been received. This function must be called from soft contexts
1523 * not from interrupt context. The driver is responsible for making
1524 * calls one at a time and in order (or using flush_to_ldisc)
1526 * n_tty_receive_buf()/producer path:
1527 * claims non-exclusive termios_rwsem
1528 * publishes read_head and canon_head
1532 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1533 char *fp, int count)
1535 struct n_tty_data *ldata = tty->disc_data;
1538 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1539 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1540 n = min_t(size_t, count, n);
1541 memcpy(read_buf_addr(ldata, head), cp, n);
1542 ldata->read_head += n;
1546 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1547 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1548 n = min_t(size_t, count, n);
1549 memcpy(read_buf_addr(ldata, head), cp, n);
1550 ldata->read_head += n;
1554 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1555 char *fp, int count)
1557 struct n_tty_data *ldata = tty->disc_data;
1558 char flag = TTY_NORMAL;
1563 if (likely(flag == TTY_NORMAL))
1564 put_tty_queue(*cp++, ldata);
1566 n_tty_receive_char_flagged(tty, *cp++, flag);
1571 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1572 char *fp, int count)
1574 char flag = TTY_NORMAL;
1579 if (likely(flag == TTY_NORMAL))
1580 n_tty_receive_char_closing(tty, *cp++);
1582 n_tty_receive_char_flagged(tty, *cp++, flag);
1587 n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1588 char *fp, int count)
1590 struct n_tty_data *ldata = tty->disc_data;
1591 char flag = TTY_NORMAL;
1596 if (likely(flag == TTY_NORMAL)) {
1597 unsigned char c = *cp++;
1601 if (I_IUCLC(tty) && L_IEXTEN(tty))
1603 if (L_EXTPROC(tty)) {
1604 put_tty_queue(c, ldata);
1607 if (!test_bit(c, ldata->char_map))
1608 n_tty_receive_char_inline(tty, c);
1609 else if (n_tty_receive_char_special(tty, c) && count) {
1612 n_tty_receive_char_lnext(tty, *cp++, flag);
1616 n_tty_receive_char_flagged(tty, *cp++, flag);
1621 n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1622 char *fp, int count)
1624 struct n_tty_data *ldata = tty->disc_data;
1625 char flag = TTY_NORMAL;
1630 if (likely(flag == TTY_NORMAL)) {
1631 unsigned char c = *cp++;
1633 if (!test_bit(c, ldata->char_map))
1634 n_tty_receive_char_fast(tty, c);
1635 else if (n_tty_receive_char_special(tty, c) && count) {
1638 n_tty_receive_char_lnext(tty, *cp++, flag);
1642 n_tty_receive_char_flagged(tty, *cp++, flag);
1646 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1647 char *fp, int count)
1649 struct n_tty_data *ldata = tty->disc_data;
1650 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1652 if (ldata->real_raw)
1653 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1654 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1655 n_tty_receive_buf_raw(tty, cp, fp, count);
1656 else if (tty->closing && !L_EXTPROC(tty))
1657 n_tty_receive_buf_closing(tty, cp, fp, count);
1660 char flag = TTY_NORMAL;
1664 n_tty_receive_char_lnext(tty, *cp++, flag);
1668 if (!preops && !I_PARMRK(tty))
1669 n_tty_receive_buf_fast(tty, cp, fp, count);
1671 n_tty_receive_buf_standard(tty, cp, fp, count);
1674 if (tty->ops->flush_chars)
1675 tty->ops->flush_chars(tty);
1678 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1680 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1681 if (waitqueue_active(&tty->read_wait))
1682 wake_up_interruptible_poll(&tty->read_wait, POLLIN);
1687 n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
1688 char *fp, int count, int flow)
1690 struct n_tty_data *ldata = tty->disc_data;
1691 int room, n, rcvd = 0;
1693 down_read(&tty->termios_rwsem);
1696 room = receive_room(tty);
1697 n = min(count, room);
1703 __receive_buf(tty, cp, fp, n);
1711 tty->receive_room = room;
1712 n_tty_check_throttle(tty);
1713 up_read(&tty->termios_rwsem);
1718 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1719 char *fp, int count)
1721 n_tty_receive_buf_common(tty, cp, fp, count, 0);
1724 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1725 char *fp, int count)
1727 return n_tty_receive_buf_common(tty, cp, fp, count, 1);
1730 int is_ignored(int sig)
1732 return (sigismember(¤t->blocked, sig) ||
1733 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1737 * n_tty_set_termios - termios data changed
1739 * @old: previous data
1741 * Called by the tty layer when the user changes termios flags so
1742 * that the line discipline can plan ahead. This function cannot sleep
1743 * and is protected from re-entry by the tty layer. The user is
1744 * guaranteed that this function will not be re-entered or in progress
1745 * when the ldisc is closed.
1747 * Locking: Caller holds tty->termios_rwsem
1750 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1752 struct n_tty_data *ldata = tty->disc_data;
1754 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) {
1755 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1756 ldata->line_start = ldata->read_tail;
1757 if (!L_ICANON(tty) || !read_cnt(ldata)) {
1758 ldata->canon_head = ldata->read_tail;
1761 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1),
1763 ldata->canon_head = ldata->read_head;
1770 ldata->icanon = (L_ICANON(tty) != 0);
1772 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1773 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1774 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1776 bitmap_zero(ldata->char_map, 256);
1778 if (I_IGNCR(tty) || I_ICRNL(tty))
1779 set_bit('\r', ldata->char_map);
1781 set_bit('\n', ldata->char_map);
1783 if (L_ICANON(tty)) {
1784 set_bit(ERASE_CHAR(tty), ldata->char_map);
1785 set_bit(KILL_CHAR(tty), ldata->char_map);
1786 set_bit(EOF_CHAR(tty), ldata->char_map);
1787 set_bit('\n', ldata->char_map);
1788 set_bit(EOL_CHAR(tty), ldata->char_map);
1789 if (L_IEXTEN(tty)) {
1790 set_bit(WERASE_CHAR(tty), ldata->char_map);
1791 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1792 set_bit(EOL2_CHAR(tty), ldata->char_map);
1794 set_bit(REPRINT_CHAR(tty),
1799 set_bit(START_CHAR(tty), ldata->char_map);
1800 set_bit(STOP_CHAR(tty), ldata->char_map);
1803 set_bit(INTR_CHAR(tty), ldata->char_map);
1804 set_bit(QUIT_CHAR(tty), ldata->char_map);
1805 set_bit(SUSP_CHAR(tty), ldata->char_map);
1807 clear_bit(__DISABLED_CHAR, ldata->char_map);
1809 ldata->real_raw = 0;
1812 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1813 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1814 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1815 ldata->real_raw = 1;
1817 ldata->real_raw = 0;
1819 n_tty_set_room(tty);
1821 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1822 * been stopped by STOP_CHAR(tty) before it.
1824 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1826 process_echoes(tty);
1829 /* The termios change make the tty ready for I/O */
1830 if (waitqueue_active(&tty->write_wait))
1831 wake_up_interruptible(&tty->write_wait);
1832 if (waitqueue_active(&tty->read_wait))
1833 wake_up_interruptible(&tty->read_wait);
1837 * n_tty_close - close the ldisc for this tty
1840 * Called from the terminal layer when this line discipline is
1841 * being shut down, either because of a close or becsuse of a
1842 * discipline change. The function will not be called while other
1843 * ldisc methods are in progress.
1846 static void n_tty_close(struct tty_struct *tty)
1848 struct n_tty_data *ldata = tty->disc_data;
1851 n_tty_packet_mode_flush(tty);
1854 tty->disc_data = NULL;
1858 * n_tty_open - open an ldisc
1859 * @tty: terminal to open
1861 * Called when this line discipline is being attached to the
1862 * terminal device. Can sleep. Called serialized so that no
1863 * other events will occur in parallel. No further open will occur
1867 static int n_tty_open(struct tty_struct *tty)
1869 struct n_tty_data *ldata;
1871 /* Currently a malloc failure here can panic */
1872 ldata = vmalloc(sizeof(*ldata));
1876 ldata->overrun_time = jiffies;
1877 mutex_init(&ldata->atomic_read_lock);
1878 mutex_init(&ldata->output_lock);
1880 tty->disc_data = ldata;
1881 reset_buffer_flags(tty->disc_data);
1883 ldata->canon_column = 0;
1884 ldata->minimum_to_wake = 1;
1885 ldata->num_overrun = 0;
1889 /* indicate buffer work may resume */
1890 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1891 n_tty_set_termios(tty, NULL);
1892 tty_unthrottle(tty);
1899 static inline int input_available_p(struct tty_struct *tty, int poll)
1901 struct n_tty_data *ldata = tty->disc_data;
1902 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1;
1904 if (ldata->icanon && !L_EXTPROC(tty))
1905 return ldata->canon_head != ldata->read_tail;
1907 return read_cnt(ldata) >= amt;
1911 * copy_from_read_buf - copy read data directly
1912 * @tty: terminal device
1916 * Helper function to speed up n_tty_read. It is only called when
1917 * ICANON is off; it copies characters straight from the tty queue to
1918 * user space directly. It can be profitably called twice; once to
1919 * drain the space from the tail pointer to the (physical) end of the
1920 * buffer, and once to drain the space from the (physical) beginning of
1921 * the buffer to head pointer.
1923 * Called under the ldata->atomic_read_lock sem
1925 * n_tty_read()/consumer path:
1926 * caller holds non-exclusive termios_rwsem
1927 * read_tail published
1930 static int copy_from_read_buf(struct tty_struct *tty,
1931 unsigned char __user **b,
1935 struct n_tty_data *ldata = tty->disc_data;
1939 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1942 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1945 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1947 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1948 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1950 ldata->read_tail += n;
1951 /* Turn single EOF into zero-length read */
1952 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1961 * canon_copy_from_read_buf - copy read data in canonical mode
1962 * @tty: terminal device
1966 * Helper function for n_tty_read. It is only called when ICANON is on;
1967 * it copies one line of input up to and including the line-delimiting
1968 * character into the user-space buffer.
1970 * NB: When termios is changed from non-canonical to canonical mode and
1971 * the read buffer contains data, n_tty_set_termios() simulates an EOF
1972 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer.
1973 * This causes data already processed as input to be immediately available
1974 * as input although a newline has not been received.
1976 * Called under the atomic_read_lock mutex
1978 * n_tty_read()/consumer path:
1979 * caller holds non-exclusive termios_rwsem
1980 * read_tail published
1983 static int canon_copy_from_read_buf(struct tty_struct *tty,
1984 unsigned char __user **b,
1987 struct n_tty_data *ldata = tty->disc_data;
1988 size_t n, size, more, c;
1994 /* N.B. avoid overrun if nr == 0 */
1995 n = min(*nr, read_cnt(ldata));
1999 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
2000 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
2002 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
2003 __func__, *nr, tail, n, size);
2005 eol = find_next_bit(ldata->read_flags, size, tail);
2006 more = n - (size - tail);
2007 if (eol == N_TTY_BUF_SIZE && more) {
2008 /* scan wrapped without finding set bit */
2009 eol = find_next_bit(ldata->read_flags, more, 0);
2012 } else if (eol != size)
2015 size = N_TTY_BUF_SIZE - tail;
2022 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
2024 eof_push = !n && ldata->read_tail != ldata->line_start;
2027 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2028 __func__, eol, found, n, c, size, more);
2031 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2034 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2036 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2044 clear_bit(eol, ldata->read_flags);
2045 smp_mb__after_atomic();
2046 ldata->read_tail += c;
2050 ldata->line_start = ldata->read_tail;
2053 tty_audit_push(tty);
2055 return eof_push ? -EAGAIN : 0;
2058 extern ssize_t redirected_tty_write(struct file *, const char __user *,
2062 * job_control - check job control
2064 * @file: file handle
2066 * Perform job control management checks on this file/tty descriptor
2067 * and if appropriate send any needed signals and return a negative
2068 * error code if action should be taken.
2070 * Locking: redirected write test is safe
2071 * current->signal->tty check is safe
2072 * ctrl_lock to safely reference tty->pgrp
2075 static int job_control(struct tty_struct *tty, struct file *file)
2077 /* Job control check -- must be done at start and after
2078 every sleep (POSIX.1 7.1.1.4). */
2079 /* NOTE: not yet done after every sleep pending a thorough
2080 check of the logic of this change. -- jlc */
2081 /* don't stop on /dev/console */
2082 if (file->f_op->write == redirected_tty_write ||
2083 current->signal->tty != tty)
2086 spin_lock_irq(&tty->ctrl_lock);
2088 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2089 else if (task_pgrp(current) != tty->pgrp) {
2090 spin_unlock_irq(&tty->ctrl_lock);
2091 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2093 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2094 set_thread_flag(TIF_SIGPENDING);
2095 return -ERESTARTSYS;
2097 spin_unlock_irq(&tty->ctrl_lock);
2103 * n_tty_read - read function for tty
2105 * @file: file object
2106 * @buf: userspace buffer pointer
2109 * Perform reads for the line discipline. We are guaranteed that the
2110 * line discipline will not be closed under us but we may get multiple
2111 * parallel readers and must handle this ourselves. We may also get
2112 * a hangup. Always called in user context, may sleep.
2114 * This code must be sure never to sleep through a hangup.
2116 * n_tty_read()/consumer path:
2117 * claims non-exclusive termios_rwsem
2118 * publishes read_tail
2121 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2122 unsigned char __user *buf, size_t nr)
2124 struct n_tty_data *ldata = tty->disc_data;
2125 unsigned char __user *b = buf;
2126 DECLARE_WAITQUEUE(wait, current);
2131 unsigned long flags;
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_irqsave(&tty->link->ctrl_lock, flags);
2178 cs = tty->link->ctrl_status;
2179 tty->link->ctrl_status = 0;
2180 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2181 if (tty_put_user(tty, cs, b++)) {
2189 /* This statement must be first before checking for input
2190 so that any interrupt will set the state back to
2192 set_current_state(TASK_INTERRUPTIBLE);
2194 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2195 ((minimum - (b - buf)) >= 1))
2196 ldata->minimum_to_wake = (minimum - (b - buf));
2198 if (!input_available_p(tty, 0)) {
2199 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2200 up_read(&tty->termios_rwsem);
2201 tty_flush_to_ldisc(tty);
2202 down_read(&tty->termios_rwsem);
2203 if (!input_available_p(tty, 0)) {
2208 if (tty_hung_up_p(file))
2212 if (file->f_flags & O_NONBLOCK) {
2216 if (signal_pending(current)) {
2217 retval = -ERESTARTSYS;
2220 n_tty_set_room(tty);
2221 up_read(&tty->termios_rwsem);
2223 timeout = schedule_timeout(timeout);
2225 down_read(&tty->termios_rwsem);
2229 __set_current_state(TASK_RUNNING);
2231 /* Deal with packet mode. */
2232 if (packet && b == buf) {
2233 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2241 if (ldata->icanon && !L_EXTPROC(tty)) {
2242 retval = canon_copy_from_read_buf(tty, &b, &nr);
2243 if (retval == -EAGAIN) {
2250 /* The copy function takes the read lock and handles
2251 locking internally for this case */
2252 uncopied = copy_from_read_buf(tty, &b, &nr);
2253 uncopied += copy_from_read_buf(tty, &b, &nr);
2260 n_tty_check_unthrottle(tty);
2262 if (b - buf >= minimum)
2267 n_tty_set_room(tty);
2268 up_read(&tty->termios_rwsem);
2270 remove_wait_queue(&tty->read_wait, &wait);
2271 if (!waitqueue_active(&tty->read_wait))
2272 ldata->minimum_to_wake = minimum;
2274 mutex_unlock(&ldata->atomic_read_lock);
2276 __set_current_state(TASK_RUNNING);
2284 * n_tty_write - write function for tty
2286 * @file: file object
2287 * @buf: userspace buffer pointer
2290 * Write function of the terminal device. This is serialized with
2291 * respect to other write callers but not to termios changes, reads
2292 * and other such events. Since the receive code will echo characters,
2293 * thus calling driver write methods, the output_lock is used in
2294 * the output processing functions called here as well as in the
2295 * echo processing function to protect the column state and space
2296 * left in the buffer.
2298 * This code must be sure never to sleep through a hangup.
2300 * Locking: output_lock to protect column state and space left
2301 * (note that the process_output*() functions take this
2305 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2306 const unsigned char *buf, size_t nr)
2308 const unsigned char *b = buf;
2309 DECLARE_WAITQUEUE(wait, current);
2313 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2314 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2315 retval = tty_check_change(tty);
2320 down_read(&tty->termios_rwsem);
2322 /* Write out any echoed characters that are still pending */
2323 process_echoes(tty);
2325 add_wait_queue(&tty->write_wait, &wait);
2327 set_current_state(TASK_INTERRUPTIBLE);
2328 if (signal_pending(current)) {
2329 retval = -ERESTARTSYS;
2332 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2338 ssize_t num = process_output_block(tty, b, nr);
2350 if (process_output(c, tty) < 0)
2354 if (tty->ops->flush_chars)
2355 tty->ops->flush_chars(tty);
2357 struct n_tty_data *ldata = tty->disc_data;
2360 mutex_lock(&ldata->output_lock);
2361 c = tty->ops->write(tty, b, nr);
2362 mutex_unlock(&ldata->output_lock);
2375 if (file->f_flags & O_NONBLOCK) {
2379 up_read(&tty->termios_rwsem);
2383 down_read(&tty->termios_rwsem);
2386 __set_current_state(TASK_RUNNING);
2387 remove_wait_queue(&tty->write_wait, &wait);
2388 if (b - buf != nr && tty->fasync)
2389 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2390 up_read(&tty->termios_rwsem);
2391 return (b - buf) ? b - buf : retval;
2395 * n_tty_poll - poll method for N_TTY
2396 * @tty: terminal device
2397 * @file: file accessing it
2400 * Called when the line discipline is asked to poll() for data or
2401 * for special events. This code is not serialized with respect to
2402 * other events save open/close.
2404 * This code must be sure never to sleep through a hangup.
2405 * Called without the kernel lock held - fine
2408 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2411 struct n_tty_data *ldata = tty->disc_data;
2412 unsigned int mask = 0;
2414 poll_wait(file, &tty->read_wait, wait);
2415 poll_wait(file, &tty->write_wait, wait);
2416 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2418 if (input_available_p(tty, 1))
2419 mask |= POLLIN | POLLRDNORM;
2420 else if (mask & POLLHUP) {
2421 tty_flush_to_ldisc(tty);
2422 if (input_available_p(tty, 1))
2423 mask |= POLLIN | POLLRDNORM;
2425 if (tty->packet && tty->link->ctrl_status)
2426 mask |= POLLPRI | POLLIN | POLLRDNORM;
2427 if (tty_hung_up_p(file))
2429 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2430 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2431 ldata->minimum_to_wake = MIN_CHAR(tty);
2433 ldata->minimum_to_wake = 1;
2435 if (tty->ops->write && !tty_is_writelocked(tty) &&
2436 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2437 tty_write_room(tty) > 0)
2438 mask |= POLLOUT | POLLWRNORM;
2442 static unsigned long inq_canon(struct n_tty_data *ldata)
2444 size_t nr, head, tail;
2446 if (ldata->canon_head == ldata->read_tail)
2448 head = ldata->canon_head;
2449 tail = ldata->read_tail;
2451 /* Skip EOF-chars.. */
2452 while (head != tail) {
2453 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2454 read_buf(ldata, tail) == __DISABLED_CHAR)
2461 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2462 unsigned int cmd, unsigned long arg)
2464 struct n_tty_data *ldata = tty->disc_data;
2469 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2471 down_write(&tty->termios_rwsem);
2473 retval = inq_canon(ldata);
2475 retval = read_cnt(ldata);
2476 up_write(&tty->termios_rwsem);
2477 return put_user(retval, (unsigned int __user *) arg);
2479 return n_tty_ioctl_helper(tty, file, cmd, arg);
2483 static void n_tty_fasync(struct tty_struct *tty, int on)
2485 struct n_tty_data *ldata = tty->disc_data;
2487 if (!waitqueue_active(&tty->read_wait)) {
2489 ldata->minimum_to_wake = 1;
2490 else if (!tty->fasync)
2491 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2495 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2496 .magic = TTY_LDISC_MAGIC,
2499 .close = n_tty_close,
2500 .flush_buffer = n_tty_flush_buffer,
2501 .chars_in_buffer = n_tty_chars_in_buffer,
2503 .write = n_tty_write,
2504 .ioctl = n_tty_ioctl,
2505 .set_termios = n_tty_set_termios,
2507 .receive_buf = n_tty_receive_buf,
2508 .write_wakeup = n_tty_write_wakeup,
2509 .fasync = n_tty_fasync,
2510 .receive_buf2 = n_tty_receive_buf2,
2514 * n_tty_inherit_ops - inherit N_TTY methods
2515 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2517 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2521 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2523 *ops = tty_ldisc_N_TTY;
2525 ops->refcount = ops->flags = 0;
2527 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);