2 * n_tty.c --- implements the N_TTY line discipline.
4 * This code used to be in tty_io.c, but things are getting hairy
5 * enough that it made sense to split things off. (The N_TTY
6 * processing has changed so much that it's hardly recognizable,
9 * Note that the open routine for N_TTY is guaranteed never to return
10 * an error. This is because Linux will fall back to setting a line
11 * to N_TTY if it can not switch to any other line discipline.
13 * Written by Theodore Ts'o, Copyright 1994.
15 * This file also contains code originally written by Linus Torvalds,
16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994.
18 * This file may be redistributed under the terms of the GNU General Public
21 * Reduced memory usage for older ARM systems - Russell King.
23 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of
24 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu>
25 * who actually finally proved there really was a race.
27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to
28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>.
29 * Also fixed a bug in BLOCKING mode where n_tty_write returns
33 #include <linux/types.h>
34 #include <linux/major.h>
35 #include <linux/errno.h>
36 #include <linux/signal.h>
37 #include <linux/fcntl.h>
38 #include <linux/sched.h>
39 #include <linux/interrupt.h>
40 #include <linux/tty.h>
41 #include <linux/timer.h>
42 #include <linux/ctype.h>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/poll.h>
47 #include <linux/bitops.h>
48 #include <linux/audit.h>
49 #include <linux/file.h>
50 #include <linux/uaccess.h>
51 #include <linux/module.h>
52 #include <linux/ratelimit.h>
53 #include <linux/vmalloc.h>
56 /* number of characters left in xmit buffer before select has we have room */
57 #define WAKEUP_CHARS 256
60 * This defines the low- and high-watermarks for throttling and
61 * unthrottling the TTY driver. These watermarks are used for
62 * controlling the space in the read buffer.
64 #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */
65 #define TTY_THRESHOLD_UNTHROTTLE 128
68 * Special byte codes used in the echo buffer to represent operations
69 * or special handling of characters. Bytes in the echo buffer that
70 * are not part of such special blocks are treated as normal character
73 #define ECHO_OP_START 0xff
74 #define ECHO_OP_MOVE_BACK_COL 0x80
75 #define ECHO_OP_SET_CANON_COL 0x81
76 #define ECHO_OP_ERASE_TAB 0x82
78 #define ECHO_COMMIT_WATERMARK 256
79 #define ECHO_BLOCK 256
80 #define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32)
85 # define n_tty_trace(f, args...) trace_printk(f, ##args)
87 # define n_tty_trace(f, args...)
91 /* producer-published */
96 DECLARE_BITMAP(char_map, 256);
98 /* private to n_tty_receive_overrun (single-threaded) */
99 unsigned long overrun_time;
105 /* must hold exclusive termios_rwsem to reset these */
106 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
108 /* shared by producer and consumer */
109 char read_buf[N_TTY_BUF_SIZE];
110 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
111 unsigned char echo_buf[N_TTY_BUF_SIZE];
115 /* consumer-published */
119 /* protected by output lock */
121 unsigned int canon_column;
124 struct mutex atomic_read_lock;
125 struct mutex output_lock;
128 static inline size_t read_cnt(struct n_tty_data *ldata)
130 return ldata->read_head - ldata->read_tail;
133 static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
135 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
138 static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i)
140 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)];
143 static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i)
145 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
148 static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i)
150 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)];
153 static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
154 unsigned char __user *ptr)
156 struct n_tty_data *ldata = tty->disc_data;
158 tty_audit_add_data(tty, &x, 1, ldata->icanon);
159 return put_user(x, ptr);
162 static int receive_room(struct tty_struct *tty)
164 struct n_tty_data *ldata = tty->disc_data;
168 /* Multiply read_cnt by 3, since each byte might take up to
169 * three times as many spaces when PARMRK is set (depending on
170 * its flags, e.g. parity error). */
171 left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
173 left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
176 * If we are doing input canonicalization, and there are no
177 * pending newlines, let characters through without limit, so
178 * that erase characters will be handled. Other excess
179 * characters will be beeped.
182 left = ldata->icanon && ldata->canon_head == ldata->read_tail;
188 * n_tty_set_room - receive space
191 * Re-schedules the flip buffer work if space just became available.
193 * Caller holds exclusive termios_rwsem
195 * n_tty_read()/consumer path:
196 * holds non-exclusive termios_rwsem
199 static void n_tty_set_room(struct tty_struct *tty)
201 struct n_tty_data *ldata = tty->disc_data;
203 /* Did this open up the receive buffer? We may need to flip */
204 if (unlikely(ldata->no_room) && receive_room(tty)) {
207 WARN_RATELIMIT(tty->port->itty == NULL,
208 "scheduling with invalid itty\n");
209 /* see if ldisc has been killed - if so, this means that
210 * even though the ldisc has been halted and ->buf.work
211 * cancelled, ->buf.work is about to be rescheduled
213 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
214 "scheduling buffer work for halted ldisc\n");
215 queue_work(system_unbound_wq, &tty->port->buf.work);
219 static ssize_t chars_in_buffer(struct tty_struct *tty)
221 struct n_tty_data *ldata = tty->disc_data;
227 n = ldata->canon_head - ldata->read_tail;
232 * n_tty_write_wakeup - asynchronous I/O notifier
235 * Required for the ptys, serial driver etc. since processes
236 * that attach themselves to the master and rely on ASYNC
237 * IO must be woken up
240 static void n_tty_write_wakeup(struct tty_struct *tty)
242 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags))
243 kill_fasync(&tty->fasync, SIGIO, POLL_OUT);
246 static void n_tty_check_throttle(struct tty_struct *tty)
248 if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
251 * Check the remaining room for the input canonicalization
252 * mode. We don't want to throttle the driver if we're in
253 * canonical mode and don't have a newline yet!
257 tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
258 if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
260 throttled = tty_throttle_safe(tty);
264 __tty_set_flow_change(tty, 0);
267 static void n_tty_check_unthrottle(struct tty_struct *tty)
269 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
270 tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
271 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
276 n_tty_write_wakeup(tty->link);
277 wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
281 /* If there is enough space in the read buffer now, let the
282 * low-level driver know. We use chars_in_buffer() to
283 * check the buffer, as it now knows about canonical mode.
284 * Otherwise, if the driver is throttled and the line is
285 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
286 * we won't get any more characters.
291 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
292 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
297 unthrottled = tty_unthrottle_safe(tty);
301 __tty_set_flow_change(tty, 0);
305 * put_tty_queue - add character to tty
309 * Add a character to the tty read_buf queue.
311 * n_tty_receive_buf()/producer path:
312 * caller holds non-exclusive termios_rwsem
315 * read_head is only considered 'published' if canonical mode is
319 static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
321 *read_buf_addr(ldata, ldata->read_head++) = c;
325 * reset_buffer_flags - reset buffer state
326 * @tty: terminal to reset
328 * Reset the read buffer counters and clear the flags.
329 * Called from n_tty_open() and n_tty_flush_buffer().
331 * Locking: caller holds exclusive termios_rwsem
332 * (or locking is not required)
335 static void reset_buffer_flags(struct n_tty_data *ldata)
337 ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
338 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
339 ldata->line_start = 0;
342 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
345 static void n_tty_packet_mode_flush(struct tty_struct *tty)
349 spin_lock_irqsave(&tty->ctrl_lock, flags);
350 if (tty->link->packet) {
351 tty->ctrl_status |= TIOCPKT_FLUSHREAD;
352 wake_up_interruptible(&tty->link->read_wait);
354 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
358 * n_tty_flush_buffer - clean input queue
359 * @tty: terminal device
361 * Flush the input buffer. Called when the tty layer wants the
362 * buffer flushed (eg at hangup) or when the N_TTY line discipline
363 * internally has to clean the pending queue (for example some signals).
365 * Holds termios_rwsem to exclude producer/consumer while
366 * buffer indices are reset.
368 * Locking: ctrl_lock, exclusive termios_rwsem
371 static void n_tty_flush_buffer(struct tty_struct *tty)
373 down_write(&tty->termios_rwsem);
374 reset_buffer_flags(tty->disc_data);
378 n_tty_packet_mode_flush(tty);
379 up_write(&tty->termios_rwsem);
383 * n_tty_chars_in_buffer - report available bytes
386 * Report the number of characters buffered to be delivered to user
387 * at this instant in time.
389 * Locking: exclusive termios_rwsem
392 static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
396 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__);
398 down_write(&tty->termios_rwsem);
399 n = chars_in_buffer(tty);
400 up_write(&tty->termios_rwsem);
405 * is_utf8_continuation - utf8 multibyte check
408 * Returns true if the utf8 character 'c' is a multibyte continuation
409 * character. We use this to correctly compute the on screen size
410 * of the character when printing
413 static inline int is_utf8_continuation(unsigned char c)
415 return (c & 0xc0) == 0x80;
419 * is_continuation - multibyte check
422 * Returns true if the utf8 character 'c' is a multibyte continuation
423 * character and the terminal is in unicode mode.
426 static inline int is_continuation(unsigned char c, struct tty_struct *tty)
428 return I_IUTF8(tty) && is_utf8_continuation(c);
432 * do_output_char - output one character
433 * @c: character (or partial unicode symbol)
434 * @tty: terminal device
435 * @space: space available in tty driver write buffer
437 * This is a helper function that handles one output character
438 * (including special characters like TAB, CR, LF, etc.),
439 * doing OPOST processing and putting the results in the
440 * tty driver's write buffer.
442 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY
443 * and NLDLY. They simply aren't relevant in the world today.
444 * If you ever need them, add them here.
446 * Returns the number of bytes of buffer space used or -1 if
449 * Locking: should be called under the output_lock to protect
450 * the column state and space left in the buffer
453 static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
455 struct n_tty_data *ldata = tty->disc_data;
468 ldata->canon_column = ldata->column = 0;
469 tty->ops->write(tty, "\r\n", 2);
472 ldata->canon_column = ldata->column;
475 if (O_ONOCR(tty) && ldata->column == 0)
480 ldata->canon_column = ldata->column = 0;
483 ldata->canon_column = ldata->column = 0;
486 spaces = 8 - (ldata->column & 7);
487 if (O_TABDLY(tty) == XTABS) {
490 ldata->column += spaces;
491 tty->ops->write(tty, " ", spaces);
494 ldata->column += spaces;
497 if (ldata->column > 0)
504 if (!is_continuation(c, tty))
510 tty_put_char(tty, c);
515 * process_output - output post processor
516 * @c: character (or partial unicode symbol)
517 * @tty: terminal device
519 * Output one character with OPOST processing.
520 * Returns -1 when the output device is full and the character
523 * Locking: output_lock to protect column state and space left
524 * (also, this is called from n_tty_write under the
525 * tty layer write lock)
528 static int process_output(unsigned char c, struct tty_struct *tty)
530 struct n_tty_data *ldata = tty->disc_data;
533 mutex_lock(&ldata->output_lock);
535 space = tty_write_room(tty);
536 retval = do_output_char(c, tty, space);
538 mutex_unlock(&ldata->output_lock);
546 * process_output_block - block post processor
547 * @tty: terminal device
548 * @buf: character buffer
549 * @nr: number of bytes to output
551 * Output a block of characters with OPOST processing.
552 * Returns the number of characters output.
554 * This path is used to speed up block console writes, among other
555 * things when processing blocks of output data. It handles only
556 * the simple cases normally found and helps to generate blocks of
557 * symbols for the console driver and thus improve performance.
559 * Locking: output_lock to protect column state and space left
560 * (also, this is called from n_tty_write under the
561 * tty layer write lock)
564 static ssize_t process_output_block(struct tty_struct *tty,
565 const unsigned char *buf, unsigned int nr)
567 struct n_tty_data *ldata = tty->disc_data;
570 const unsigned char *cp;
572 mutex_lock(&ldata->output_lock);
574 space = tty_write_room(tty);
576 mutex_unlock(&ldata->output_lock);
582 for (i = 0, cp = buf; i < nr; i++, cp++) {
583 unsigned char c = *cp;
591 ldata->canon_column = ldata->column;
594 if (O_ONOCR(tty) && ldata->column == 0)
598 ldata->canon_column = ldata->column = 0;
603 if (ldata->column > 0)
610 if (!is_continuation(c, tty))
617 i = tty->ops->write(tty, buf, i);
619 mutex_unlock(&ldata->output_lock);
624 * process_echoes - write pending echo characters
625 * @tty: terminal device
627 * Write previously buffered echo (and other ldisc-generated)
628 * characters to the tty.
630 * Characters generated by the ldisc (including echoes) need to
631 * be buffered because the driver's write buffer can fill during
632 * heavy program output. Echoing straight to the driver will
633 * often fail under these conditions, causing lost characters and
634 * resulting mismatches of ldisc state information.
636 * Since the ldisc state must represent the characters actually sent
637 * to the driver at the time of the write, operations like certain
638 * changes in column state are also saved in the buffer and executed
641 * A circular fifo buffer is used so that the most recent characters
642 * are prioritized. Also, when control characters are echoed with a
643 * prefixed "^", the pair is treated atomically and thus not separated.
645 * Locking: callers must hold output_lock
648 static size_t __process_echoes(struct tty_struct *tty)
650 struct n_tty_data *ldata = tty->disc_data;
651 int space, old_space;
655 old_space = space = tty_write_room(tty);
657 tail = ldata->echo_tail;
658 while (ldata->echo_commit != tail) {
659 c = echo_buf(ldata, tail);
660 if (c == ECHO_OP_START) {
662 int no_space_left = 0;
665 * If the buffer byte is the start of a multi-byte
666 * operation, get the next byte, which is either the
667 * op code or a control character value.
669 op = echo_buf(ldata, tail + 1);
672 unsigned int num_chars, num_bs;
674 case ECHO_OP_ERASE_TAB:
675 num_chars = echo_buf(ldata, tail + 2);
678 * Determine how many columns to go back
679 * in order to erase the tab.
680 * This depends on the number of columns
681 * used by other characters within the tab
682 * area. If this (modulo 8) count is from
683 * the start of input rather than from a
684 * previous tab, we offset by canon column.
685 * Otherwise, tab spacing is normal.
687 if (!(num_chars & 0x80))
688 num_chars += ldata->canon_column;
689 num_bs = 8 - (num_chars & 7);
691 if (num_bs > space) {
697 tty_put_char(tty, '\b');
698 if (ldata->column > 0)
704 case ECHO_OP_SET_CANON_COL:
705 ldata->canon_column = ldata->column;
709 case ECHO_OP_MOVE_BACK_COL:
710 if (ldata->column > 0)
716 /* This is an escaped echo op start code */
721 tty_put_char(tty, ECHO_OP_START);
729 * If the op is not a special byte code,
730 * it is a ctrl char tagged to be echoed
731 * as "^X" (where X is the letter
732 * representing the control char).
733 * Note that we must ensure there is
734 * enough space for the whole ctrl pair.
741 tty_put_char(tty, '^');
742 tty_put_char(tty, op ^ 0100);
752 int retval = do_output_char(c, tty, space);
759 tty_put_char(tty, c);
766 /* If the echo buffer is nearly full (so that the possibility exists
767 * of echo overrun before the next commit), then discard enough
768 * data at the tail to prevent a subsequent overrun */
769 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
770 if (echo_buf(ldata, tail == ECHO_OP_START)) {
771 if (echo_buf(ldata, tail) == ECHO_OP_ERASE_TAB)
779 ldata->echo_tail = tail;
780 return old_space - space;
783 static void commit_echoes(struct tty_struct *tty)
785 struct n_tty_data *ldata = tty->disc_data;
786 size_t nr, old, echoed;
789 head = ldata->echo_head;
790 old = ldata->echo_commit - ldata->echo_tail;
792 /* Process committed echoes if the accumulated # of bytes
793 * is over the threshold (and try again each time another
794 * block is accumulated) */
795 nr = head - ldata->echo_tail;
796 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK))
799 mutex_lock(&ldata->output_lock);
800 ldata->echo_commit = head;
801 echoed = __process_echoes(tty);
802 mutex_unlock(&ldata->output_lock);
804 if (echoed && tty->ops->flush_chars)
805 tty->ops->flush_chars(tty);
808 static void process_echoes(struct tty_struct *tty)
810 struct n_tty_data *ldata = tty->disc_data;
813 if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_tail)
816 mutex_lock(&ldata->output_lock);
817 echoed = __process_echoes(tty);
818 mutex_unlock(&ldata->output_lock);
820 if (echoed && tty->ops->flush_chars)
821 tty->ops->flush_chars(tty);
824 static void flush_echoes(struct tty_struct *tty)
826 struct n_tty_data *ldata = tty->disc_data;
828 if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_head)
831 mutex_lock(&ldata->output_lock);
832 ldata->echo_commit = ldata->echo_head;
833 __process_echoes(tty);
834 mutex_unlock(&ldata->output_lock);
838 * add_echo_byte - add a byte to the echo buffer
839 * @c: unicode byte to echo
842 * Add a character or operation byte to the echo buffer.
845 static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata)
847 *echo_buf_addr(ldata, ldata->echo_head++) = c;
851 * echo_move_back_col - add operation to move back a column
854 * Add an operation to the echo buffer to move back one column.
857 static void echo_move_back_col(struct n_tty_data *ldata)
859 add_echo_byte(ECHO_OP_START, ldata);
860 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata);
864 * echo_set_canon_col - add operation to set the canon column
867 * Add an operation to the echo buffer to set the canon column
868 * to the current column.
871 static void echo_set_canon_col(struct n_tty_data *ldata)
873 add_echo_byte(ECHO_OP_START, ldata);
874 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata);
878 * echo_erase_tab - add operation to erase a tab
879 * @num_chars: number of character columns already used
880 * @after_tab: true if num_chars starts after a previous tab
883 * Add an operation to the echo buffer to erase a tab.
885 * Called by the eraser function, which knows how many character
886 * columns have been used since either a previous tab or the start
887 * of input. This information will be used later, along with
888 * canon column (if applicable), to go back the correct number
892 static void echo_erase_tab(unsigned int num_chars, int after_tab,
893 struct n_tty_data *ldata)
895 add_echo_byte(ECHO_OP_START, ldata);
896 add_echo_byte(ECHO_OP_ERASE_TAB, ldata);
898 /* We only need to know this modulo 8 (tab spacing) */
901 /* Set the high bit as a flag if num_chars is after a previous tab */
905 add_echo_byte(num_chars, ldata);
909 * echo_char_raw - echo a character raw
910 * @c: unicode byte to echo
911 * @tty: terminal device
913 * Echo user input back onto the screen. This must be called only when
914 * L_ECHO(tty) is true. Called from the driver receive_buf path.
916 * This variant does not treat control characters specially.
919 static void echo_char_raw(unsigned char c, struct n_tty_data *ldata)
921 if (c == ECHO_OP_START) {
922 add_echo_byte(ECHO_OP_START, ldata);
923 add_echo_byte(ECHO_OP_START, ldata);
925 add_echo_byte(c, ldata);
930 * echo_char - echo a character
931 * @c: unicode byte to echo
932 * @tty: terminal device
934 * Echo user input back onto the screen. This must be called only when
935 * L_ECHO(tty) is true. Called from the driver receive_buf path.
937 * This variant tags control characters to be echoed as "^X"
938 * (where X is the letter representing the control char).
941 static void echo_char(unsigned char c, struct tty_struct *tty)
943 struct n_tty_data *ldata = tty->disc_data;
945 if (c == ECHO_OP_START) {
946 add_echo_byte(ECHO_OP_START, ldata);
947 add_echo_byte(ECHO_OP_START, ldata);
949 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t')
950 add_echo_byte(ECHO_OP_START, ldata);
951 add_echo_byte(c, ldata);
956 * finish_erasing - complete erase
960 static inline void finish_erasing(struct n_tty_data *ldata)
962 if (ldata->erasing) {
963 echo_char_raw('/', ldata);
969 * eraser - handle erase function
970 * @c: character input
971 * @tty: terminal device
973 * Perform erase and necessary output when an erase character is
974 * present in the stream from the driver layer. Handles the complexities
975 * of UTF-8 multibyte symbols.
977 * n_tty_receive_buf()/producer path:
978 * caller holds non-exclusive termios_rwsem
981 * Modifying the read_head is not considered a publish in this context
982 * because canonical mode is active -- only canon_head publishes
985 static void eraser(unsigned char c, struct tty_struct *tty)
987 struct n_tty_data *ldata = tty->disc_data;
988 enum { ERASE, WERASE, KILL } kill_type;
993 if (ldata->read_head == ldata->canon_head) {
994 /* process_output('\a', tty); */ /* what do you think? */
997 if (c == ERASE_CHAR(tty))
999 else if (c == WERASE_CHAR(tty))
1003 ldata->read_head = ldata->canon_head;
1006 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
1007 ldata->read_head = ldata->canon_head;
1008 finish_erasing(ldata);
1009 echo_char(KILL_CHAR(tty), tty);
1010 /* Add a newline if ECHOK is on and ECHOKE is off. */
1012 echo_char_raw('\n', ldata);
1019 while (ldata->read_head != ldata->canon_head) {
1020 head = ldata->read_head;
1022 /* erase a single possibly multibyte character */
1025 c = read_buf(ldata, head);
1026 } while (is_continuation(c, tty) && head != ldata->canon_head);
1028 /* do not partially erase */
1029 if (is_continuation(c, tty))
1032 if (kill_type == WERASE) {
1033 /* Equivalent to BSD's ALTWERASE. */
1034 if (isalnum(c) || c == '_')
1036 else if (seen_alnums)
1039 cnt = ldata->read_head - head;
1040 ldata->read_head = head;
1042 if (L_ECHOPRT(tty)) {
1043 if (!ldata->erasing) {
1044 echo_char_raw('\\', ldata);
1047 /* if cnt > 1, output a multi-byte character */
1051 echo_char_raw(read_buf(ldata, head), ldata);
1052 echo_move_back_col(ldata);
1054 } else if (kill_type == ERASE && !L_ECHOE(tty)) {
1055 echo_char(ERASE_CHAR(tty), tty);
1056 } else if (c == '\t') {
1057 unsigned int num_chars = 0;
1059 size_t tail = ldata->read_head;
1062 * Count the columns used for characters
1063 * since the start of input or after a
1065 * This info is used to go back the correct
1066 * number of columns.
1068 while (tail != ldata->canon_head) {
1070 c = read_buf(ldata, tail);
1074 } else if (iscntrl(c)) {
1077 } else if (!is_continuation(c, tty)) {
1081 echo_erase_tab(num_chars, after_tab, ldata);
1083 if (iscntrl(c) && L_ECHOCTL(tty)) {
1084 echo_char_raw('\b', ldata);
1085 echo_char_raw(' ', ldata);
1086 echo_char_raw('\b', ldata);
1088 if (!iscntrl(c) || L_ECHOCTL(tty)) {
1089 echo_char_raw('\b', ldata);
1090 echo_char_raw(' ', ldata);
1091 echo_char_raw('\b', ldata);
1095 if (kill_type == ERASE)
1098 if (ldata->read_head == ldata->canon_head && L_ECHO(tty))
1099 finish_erasing(ldata);
1103 * isig - handle the ISIG optio
1107 * Called when a signal is being sent due to terminal input.
1108 * Called from the driver receive_buf path so serialized.
1110 * Locking: ctrl_lock
1113 static void isig(int sig, struct tty_struct *tty)
1115 struct pid *tty_pgrp = tty_get_pgrp(tty);
1117 kill_pgrp(tty_pgrp, sig, 1);
1123 * n_tty_receive_break - handle break
1126 * An RS232 break event has been hit in the incoming bitstream. This
1127 * can cause a variety of events depending upon the termios settings.
1129 * n_tty_receive_buf()/producer path:
1130 * caller holds non-exclusive termios_rwsem
1131 * publishes read_head via put_tty_queue()
1133 * Note: may get exclusive termios_rwsem if flushing input buffer
1136 static void n_tty_receive_break(struct tty_struct *tty)
1138 struct n_tty_data *ldata = tty->disc_data;
1142 if (I_BRKINT(tty)) {
1144 if (!L_NOFLSH(tty)) {
1145 /* flushing needs exclusive termios_rwsem */
1146 up_read(&tty->termios_rwsem);
1147 n_tty_flush_buffer(tty);
1148 tty_driver_flush_buffer(tty);
1149 down_read(&tty->termios_rwsem);
1153 if (I_PARMRK(tty)) {
1154 put_tty_queue('\377', ldata);
1155 put_tty_queue('\0', ldata);
1157 put_tty_queue('\0', ldata);
1158 wake_up_interruptible(&tty->read_wait);
1162 * n_tty_receive_overrun - handle overrun reporting
1165 * Data arrived faster than we could process it. While the tty
1166 * driver has flagged this the bits that were missed are gone
1169 * Called from the receive_buf path so single threaded. Does not
1170 * need locking as num_overrun and overrun_time are function
1174 static void n_tty_receive_overrun(struct tty_struct *tty)
1176 struct n_tty_data *ldata = tty->disc_data;
1179 ldata->num_overrun++;
1180 if (time_after(jiffies, ldata->overrun_time + HZ) ||
1181 time_after(ldata->overrun_time, jiffies)) {
1182 printk(KERN_WARNING "%s: %d input overrun(s)\n",
1184 ldata->num_overrun);
1185 ldata->overrun_time = jiffies;
1186 ldata->num_overrun = 0;
1191 * n_tty_receive_parity_error - error notifier
1192 * @tty: terminal device
1195 * Process a parity error and queue the right data to indicate
1196 * the error case if necessary.
1198 * n_tty_receive_buf()/producer path:
1199 * caller holds non-exclusive termios_rwsem
1200 * publishes read_head via put_tty_queue()
1202 static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
1204 struct n_tty_data *ldata = tty->disc_data;
1208 if (I_PARMRK(tty)) {
1209 put_tty_queue('\377', ldata);
1210 put_tty_queue('\0', ldata);
1211 put_tty_queue(c, ldata);
1212 } else if (I_INPCK(tty))
1213 put_tty_queue('\0', ldata);
1215 put_tty_queue(c, ldata);
1216 wake_up_interruptible(&tty->read_wait);
1220 n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
1222 if (!L_NOFLSH(tty)) {
1223 /* flushing needs exclusive termios_rwsem */
1224 up_read(&tty->termios_rwsem);
1225 n_tty_flush_buffer(tty);
1226 tty_driver_flush_buffer(tty);
1227 down_read(&tty->termios_rwsem);
1240 * n_tty_receive_char - perform processing
1241 * @tty: terminal device
1244 * Process an individual character of input received from the driver.
1245 * This is serialized with respect to itself by the rules for the
1248 * n_tty_receive_buf()/producer path:
1249 * caller holds non-exclusive termios_rwsem
1250 * publishes canon_head if canonical mode is active
1251 * otherwise, publishes read_head via put_tty_queue()
1253 * Returns 1 if LNEXT was received, else returns 0
1257 n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
1259 struct n_tty_data *ldata = tty->disc_data;
1263 if (c == START_CHAR(tty)) {
1268 if (c == STOP_CHAR(tty)) {
1275 if (c == INTR_CHAR(tty)) {
1276 n_tty_receive_signal_char(tty, SIGINT, c);
1278 } else if (c == QUIT_CHAR(tty)) {
1279 n_tty_receive_signal_char(tty, SIGQUIT, c);
1281 } else if (c == SUSP_CHAR(tty)) {
1282 n_tty_receive_signal_char(tty, SIGTSTP, c);
1287 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1289 process_echoes(tty);
1297 } else if (c == '\n' && I_INLCR(tty))
1300 if (ldata->icanon) {
1301 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
1302 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
1307 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
1310 finish_erasing(ldata);
1311 if (L_ECHOCTL(tty)) {
1312 echo_char_raw('^', ldata);
1313 echo_char_raw('\b', ldata);
1319 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
1320 size_t tail = ldata->canon_head;
1322 finish_erasing(ldata);
1324 echo_char_raw('\n', ldata);
1325 while (tail != ldata->read_head) {
1326 echo_char(read_buf(ldata, tail), tty);
1333 if (L_ECHO(tty) || L_ECHONL(tty)) {
1334 echo_char_raw('\n', ldata);
1337 goto handle_newline;
1339 if (c == EOF_CHAR(tty)) {
1340 c = __DISABLED_CHAR;
1341 goto handle_newline;
1343 if ((c == EOL_CHAR(tty)) ||
1344 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
1345 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
1348 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
1351 /* Record the column of first canon char. */
1352 if (ldata->canon_head == ldata->read_head)
1353 echo_set_canon_col(ldata);
1358 * XXX does PARMRK doubling happen for
1359 * EOL_CHAR and EOL2_CHAR?
1362 put_tty_queue(c, ldata);
1365 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
1366 put_tty_queue(c, ldata);
1367 ldata->canon_head = ldata->read_head;
1368 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1369 if (waitqueue_active(&tty->read_wait))
1370 wake_up_interruptible(&tty->read_wait);
1375 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1377 finish_erasing(ldata);
1379 echo_char_raw('\n', ldata);
1381 /* Record the column of first canon char. */
1382 if (ldata->canon_head == ldata->read_head)
1383 echo_set_canon_col(ldata);
1390 put_tty_queue(c, ldata);
1392 put_tty_queue(c, ldata);
1397 n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
1399 struct n_tty_data *ldata = tty->disc_data;
1402 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1404 process_echoes(tty);
1407 finish_erasing(ldata);
1408 /* Record the column of first canon char. */
1409 if (ldata->canon_head == ldata->read_head)
1410 echo_set_canon_col(ldata);
1414 parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
1416 put_tty_queue(c, ldata);
1417 put_tty_queue(c, ldata);
1420 static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
1422 n_tty_receive_char_inline(tty, c);
1426 n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
1428 struct n_tty_data *ldata = tty->disc_data;
1430 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
1432 process_echoes(tty);
1435 finish_erasing(ldata);
1436 /* Record the column of first canon char. */
1437 if (ldata->canon_head == ldata->read_head)
1438 echo_set_canon_col(ldata);
1442 put_tty_queue(c, ldata);
1446 n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
1450 if (I_IUCLC(tty) && L_IEXTEN(tty))
1454 if (c == STOP_CHAR(tty))
1456 else if (c == START_CHAR(tty) ||
1457 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) &&
1458 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
1459 c != SUSP_CHAR(tty))) {
1461 process_echoes(tty);
1467 n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
1473 n_tty_receive_break(tty);
1477 n_tty_receive_parity_error(tty, c);
1480 n_tty_receive_overrun(tty);
1483 printk(KERN_ERR "%s: unknown flag %d\n",
1484 tty_name(tty, buf), flag);
1490 n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
1492 struct n_tty_data *ldata = tty->disc_data;
1495 if (likely(flag == TTY_NORMAL)) {
1498 if (I_IUCLC(tty) && L_IEXTEN(tty))
1500 n_tty_receive_char(tty, c);
1502 n_tty_receive_char_flagged(tty, c, flag);
1506 * n_tty_receive_buf - data receive
1507 * @tty: terminal device
1510 * @count: characters
1512 * Called by the terminal driver when a block of characters has
1513 * been received. This function must be called from soft contexts
1514 * not from interrupt context. The driver is responsible for making
1515 * calls one at a time and in order (or using flush_to_ldisc)
1517 * n_tty_receive_buf()/producer path:
1518 * claims non-exclusive termios_rwsem
1519 * publishes read_head and canon_head
1523 n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
1524 char *fp, int count)
1526 struct n_tty_data *ldata = tty->disc_data;
1529 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1530 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1531 n = min_t(size_t, count, n);
1532 memcpy(read_buf_addr(ldata, head), cp, n);
1533 ldata->read_head += n;
1537 head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
1538 n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
1539 n = min_t(size_t, count, n);
1540 memcpy(read_buf_addr(ldata, head), cp, n);
1541 ldata->read_head += n;
1545 n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
1546 char *fp, int count)
1548 struct n_tty_data *ldata = tty->disc_data;
1549 char flag = TTY_NORMAL;
1554 if (likely(flag == TTY_NORMAL))
1555 put_tty_queue(*cp++, ldata);
1557 n_tty_receive_char_flagged(tty, *cp++, flag);
1562 n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
1563 char *fp, int count)
1565 char flag = TTY_NORMAL;
1570 if (likely(flag == TTY_NORMAL))
1571 n_tty_receive_char_closing(tty, *cp++);
1573 n_tty_receive_char_flagged(tty, *cp++, flag);
1578 n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
1579 char *fp, int count)
1581 struct n_tty_data *ldata = tty->disc_data;
1582 char flag = TTY_NORMAL;
1587 if (likely(flag == TTY_NORMAL)) {
1588 unsigned char c = *cp++;
1592 if (I_IUCLC(tty) && L_IEXTEN(tty))
1594 if (L_EXTPROC(tty)) {
1595 put_tty_queue(c, ldata);
1598 if (!test_bit(c, ldata->char_map))
1599 n_tty_receive_char_inline(tty, c);
1600 else if (n_tty_receive_char_special(tty, c) && count) {
1603 n_tty_receive_char_lnext(tty, *cp++, flag);
1607 n_tty_receive_char_flagged(tty, *cp++, flag);
1612 n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
1613 char *fp, int count)
1615 struct n_tty_data *ldata = tty->disc_data;
1616 char flag = TTY_NORMAL;
1621 if (likely(flag == TTY_NORMAL)) {
1622 unsigned char c = *cp++;
1624 if (!test_bit(c, ldata->char_map))
1625 n_tty_receive_char_fast(tty, c);
1626 else if (n_tty_receive_char_special(tty, c) && count) {
1629 n_tty_receive_char_lnext(tty, *cp++, flag);
1633 n_tty_receive_char_flagged(tty, *cp++, flag);
1637 static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
1638 char *fp, int count)
1640 struct n_tty_data *ldata = tty->disc_data;
1641 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
1643 if (ldata->real_raw)
1644 n_tty_receive_buf_real_raw(tty, cp, fp, count);
1645 else if (ldata->raw || (L_EXTPROC(tty) && !preops))
1646 n_tty_receive_buf_raw(tty, cp, fp, count);
1647 else if (tty->closing && !L_EXTPROC(tty))
1648 n_tty_receive_buf_closing(tty, cp, fp, count);
1651 char flag = TTY_NORMAL;
1655 n_tty_receive_char_lnext(tty, *cp++, flag);
1659 if (!preops && !I_PARMRK(tty))
1660 n_tty_receive_buf_fast(tty, cp, fp, count);
1662 n_tty_receive_buf_standard(tty, cp, fp, count);
1665 if (tty->ops->flush_chars)
1666 tty->ops->flush_chars(tty);
1669 if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
1671 kill_fasync(&tty->fasync, SIGIO, POLL_IN);
1672 if (waitqueue_active(&tty->read_wait))
1673 wake_up_interruptible(&tty->read_wait);
1677 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
1678 char *fp, int count)
1682 down_read(&tty->termios_rwsem);
1685 room = receive_room(tty);
1686 n = min(count, room);
1689 __receive_buf(tty, cp, fp, n);
1696 tty->receive_room = room;
1697 n_tty_check_throttle(tty);
1698 up_read(&tty->termios_rwsem);
1701 static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
1702 char *fp, int count)
1704 struct n_tty_data *ldata = tty->disc_data;
1705 int room, n, rcvd = 0;
1707 down_read(&tty->termios_rwsem);
1710 room = receive_room(tty);
1711 n = min(count, room);
1717 __receive_buf(tty, cp, fp, n);
1725 tty->receive_room = room;
1726 n_tty_check_throttle(tty);
1727 up_read(&tty->termios_rwsem);
1732 int is_ignored(int sig)
1734 return (sigismember(¤t->blocked, sig) ||
1735 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN);
1739 * n_tty_set_termios - termios data changed
1741 * @old: previous data
1743 * Called by the tty layer when the user changes termios flags so
1744 * that the line discipline can plan ahead. This function cannot sleep
1745 * and is protected from re-entry by the tty layer. The user is
1746 * guaranteed that this function will not be re-entered or in progress
1747 * when the ldisc is closed.
1749 * Locking: Caller holds tty->termios_rwsem
1752 static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
1754 struct n_tty_data *ldata = tty->disc_data;
1755 int canon_change = 1;
1758 canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
1760 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
1761 ldata->line_start = ldata->canon_head = ldata->read_tail;
1766 if (canon_change && !L_ICANON(tty) && read_cnt(ldata))
1767 wake_up_interruptible(&tty->read_wait);
1769 ldata->icanon = (L_ICANON(tty) != 0);
1771 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
1772 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) ||
1773 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) ||
1775 bitmap_zero(ldata->char_map, 256);
1777 if (I_IGNCR(tty) || I_ICRNL(tty))
1778 set_bit('\r', ldata->char_map);
1780 set_bit('\n', ldata->char_map);
1782 if (L_ICANON(tty)) {
1783 set_bit(ERASE_CHAR(tty), ldata->char_map);
1784 set_bit(KILL_CHAR(tty), ldata->char_map);
1785 set_bit(EOF_CHAR(tty), ldata->char_map);
1786 set_bit('\n', ldata->char_map);
1787 set_bit(EOL_CHAR(tty), ldata->char_map);
1788 if (L_IEXTEN(tty)) {
1789 set_bit(WERASE_CHAR(tty), ldata->char_map);
1790 set_bit(LNEXT_CHAR(tty), ldata->char_map);
1791 set_bit(EOL2_CHAR(tty), ldata->char_map);
1793 set_bit(REPRINT_CHAR(tty),
1798 set_bit(START_CHAR(tty), ldata->char_map);
1799 set_bit(STOP_CHAR(tty), ldata->char_map);
1802 set_bit(INTR_CHAR(tty), ldata->char_map);
1803 set_bit(QUIT_CHAR(tty), ldata->char_map);
1804 set_bit(SUSP_CHAR(tty), ldata->char_map);
1806 clear_bit(__DISABLED_CHAR, ldata->char_map);
1808 ldata->real_raw = 0;
1811 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) &&
1812 (I_IGNPAR(tty) || !I_INPCK(tty)) &&
1813 (tty->driver->flags & TTY_DRIVER_REAL_RAW))
1814 ldata->real_raw = 1;
1816 ldata->real_raw = 0;
1818 n_tty_set_room(tty);
1820 * Fix tty hang when I_IXON(tty) is cleared, but the tty
1821 * been stopped by STOP_CHAR(tty) before it.
1823 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {
1827 /* The termios change make the tty ready for I/O */
1828 wake_up_interruptible(&tty->write_wait);
1829 wake_up_interruptible(&tty->read_wait);
1833 * n_tty_close - close the ldisc for this tty
1836 * Called from the terminal layer when this line discipline is
1837 * being shut down, either because of a close or becsuse of a
1838 * discipline change. The function will not be called while other
1839 * ldisc methods are in progress.
1842 static void n_tty_close(struct tty_struct *tty)
1844 struct n_tty_data *ldata = tty->disc_data;
1847 n_tty_packet_mode_flush(tty);
1850 tty->disc_data = NULL;
1854 * n_tty_open - open an ldisc
1855 * @tty: terminal to open
1857 * Called when this line discipline is being attached to the
1858 * terminal device. Can sleep. Called serialized so that no
1859 * other events will occur in parallel. No further open will occur
1863 static int n_tty_open(struct tty_struct *tty)
1865 struct n_tty_data *ldata;
1867 /* Currently a malloc failure here can panic */
1868 ldata = vmalloc(sizeof(*ldata));
1872 ldata->overrun_time = jiffies;
1873 mutex_init(&ldata->atomic_read_lock);
1874 mutex_init(&ldata->output_lock);
1876 tty->disc_data = ldata;
1877 reset_buffer_flags(tty->disc_data);
1879 ldata->canon_column = 0;
1880 ldata->minimum_to_wake = 1;
1881 ldata->num_overrun = 0;
1885 /* indicate buffer work may resume */
1886 clear_bit(TTY_LDISC_HALTED, &tty->flags);
1887 n_tty_set_termios(tty, NULL);
1888 tty_unthrottle(tty);
1895 static inline int input_available_p(struct tty_struct *tty, int amt)
1897 struct n_tty_data *ldata = tty->disc_data;
1899 if (ldata->icanon && !L_EXTPROC(tty)) {
1900 if (ldata->canon_head != ldata->read_tail)
1902 } else if (read_cnt(ldata) >= (amt ? amt : 1))
1909 * copy_from_read_buf - copy read data directly
1910 * @tty: terminal device
1914 * Helper function to speed up n_tty_read. It is only called when
1915 * ICANON is off; it copies characters straight from the tty queue to
1916 * user space directly. It can be profitably called twice; once to
1917 * drain the space from the tail pointer to the (physical) end of the
1918 * buffer, and once to drain the space from the (physical) beginning of
1919 * the buffer to head pointer.
1921 * Called under the ldata->atomic_read_lock sem
1923 * n_tty_read()/consumer path:
1924 * caller holds non-exclusive termios_rwsem
1925 * read_tail published
1928 static int copy_from_read_buf(struct tty_struct *tty,
1929 unsigned char __user **b,
1933 struct n_tty_data *ldata = tty->disc_data;
1937 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1940 n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
1943 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
1945 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
1946 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
1948 ldata->read_tail += n;
1949 /* Turn single EOF into zero-length read */
1950 if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
1959 * canon_copy_from_read_buf - copy read data in canonical mode
1960 * @tty: terminal device
1964 * Helper function for n_tty_read. It is only called when ICANON is on;
1965 * it copies one line of input up to and including the line-delimiting
1966 * character into the user-space buffer.
1968 * Called under the atomic_read_lock mutex
1970 * n_tty_read()/consumer path:
1971 * caller holds non-exclusive termios_rwsem
1972 * read_tail published
1975 static int canon_copy_from_read_buf(struct tty_struct *tty,
1976 unsigned char __user **b,
1979 struct n_tty_data *ldata = tty->disc_data;
1980 size_t n, size, more, c;
1986 /* N.B. avoid overrun if nr == 0 */
1987 n = min(*nr, read_cnt(ldata));
1991 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
1992 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
1994 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n",
1995 __func__, *nr, tail, n, size);
1997 eol = find_next_bit(ldata->read_flags, size, tail);
1998 more = n - (size - tail);
1999 if (eol == N_TTY_BUF_SIZE && more) {
2000 /* scan wrapped without finding set bit */
2001 eol = find_next_bit(ldata->read_flags, more, 0);
2004 } else if (eol != size)
2007 size = N_TTY_BUF_SIZE - tail;
2008 n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
2011 if (found && read_buf(ldata, eol) == __DISABLED_CHAR) {
2013 eof_push = !n && ldata->read_tail != ldata->line_start;
2016 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
2017 __func__, eol, found, n, c, size, more);
2020 ret = copy_to_user(*b, read_buf_addr(ldata, tail), size);
2023 ret = copy_to_user(*b + size, ldata->read_buf, n - size);
2025 ret = copy_to_user(*b, read_buf_addr(ldata, tail), n);
2033 clear_bit(eol, ldata->read_flags);
2034 smp_mb__after_clear_bit();
2035 ldata->read_tail += c;
2038 ldata->line_start = ldata->read_tail;
2039 tty_audit_push(tty);
2041 return eof_push ? -EAGAIN : 0;
2044 extern ssize_t redirected_tty_write(struct file *, const char __user *,
2048 * job_control - check job control
2050 * @file: file handle
2052 * Perform job control management checks on this file/tty descriptor
2053 * and if appropriate send any needed signals and return a negative
2054 * error code if action should be taken.
2056 * Locking: redirected write test is safe
2057 * current->signal->tty check is safe
2058 * ctrl_lock to safely reference tty->pgrp
2061 static int job_control(struct tty_struct *tty, struct file *file)
2063 /* Job control check -- must be done at start and after
2064 every sleep (POSIX.1 7.1.1.4). */
2065 /* NOTE: not yet done after every sleep pending a thorough
2066 check of the logic of this change. -- jlc */
2067 /* don't stop on /dev/console */
2068 if (file->f_op->write == redirected_tty_write ||
2069 current->signal->tty != tty)
2072 spin_lock_irq(&tty->ctrl_lock);
2074 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n");
2075 else if (task_pgrp(current) != tty->pgrp) {
2076 spin_unlock_irq(&tty->ctrl_lock);
2077 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned())
2079 kill_pgrp(task_pgrp(current), SIGTTIN, 1);
2080 set_thread_flag(TIF_SIGPENDING);
2081 return -ERESTARTSYS;
2083 spin_unlock_irq(&tty->ctrl_lock);
2089 * n_tty_read - read function for tty
2091 * @file: file object
2092 * @buf: userspace buffer pointer
2095 * Perform reads for the line discipline. We are guaranteed that the
2096 * line discipline will not be closed under us but we may get multiple
2097 * parallel readers and must handle this ourselves. We may also get
2098 * a hangup. Always called in user context, may sleep.
2100 * This code must be sure never to sleep through a hangup.
2102 * n_tty_read()/consumer path:
2103 * claims non-exclusive termios_rwsem
2104 * publishes read_tail
2107 static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
2108 unsigned char __user *buf, size_t nr)
2110 struct n_tty_data *ldata = tty->disc_data;
2111 unsigned char __user *b = buf;
2112 DECLARE_WAITQUEUE(wait, current);
2117 unsigned long flags;
2120 c = job_control(tty, file);
2125 * Internal serialization of reads.
2127 if (file->f_flags & O_NONBLOCK) {
2128 if (!mutex_trylock(&ldata->atomic_read_lock))
2131 if (mutex_lock_interruptible(&ldata->atomic_read_lock))
2132 return -ERESTARTSYS;
2135 down_read(&tty->termios_rwsem);
2138 timeout = MAX_SCHEDULE_TIMEOUT;
2139 if (!ldata->icanon) {
2140 minimum = MIN_CHAR(tty);
2142 time = (HZ / 10) * TIME_CHAR(tty);
2144 ldata->minimum_to_wake = 1;
2145 else if (!waitqueue_active(&tty->read_wait) ||
2146 (ldata->minimum_to_wake > minimum))
2147 ldata->minimum_to_wake = minimum;
2149 timeout = (HZ / 10) * TIME_CHAR(tty);
2150 ldata->minimum_to_wake = minimum = 1;
2154 packet = tty->packet;
2156 add_wait_queue(&tty->read_wait, &wait);
2158 /* First test for status change. */
2159 if (packet && tty->link->ctrl_status) {
2163 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
2164 cs = tty->link->ctrl_status;
2165 tty->link->ctrl_status = 0;
2166 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
2167 if (tty_put_user(tty, cs, b++)) {
2175 /* This statement must be first before checking for input
2176 so that any interrupt will set the state back to
2178 set_current_state(TASK_INTERRUPTIBLE);
2180 if (((minimum - (b - buf)) < ldata->minimum_to_wake) &&
2181 ((minimum - (b - buf)) >= 1))
2182 ldata->minimum_to_wake = (minimum - (b - buf));
2184 if (!input_available_p(tty, 0)) {
2185 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
2189 if (tty_hung_up_p(file))
2193 if (file->f_flags & O_NONBLOCK) {
2197 if (signal_pending(current)) {
2198 retval = -ERESTARTSYS;
2201 n_tty_set_room(tty);
2202 up_read(&tty->termios_rwsem);
2204 timeout = schedule_timeout(timeout);
2206 down_read(&tty->termios_rwsem);
2209 __set_current_state(TASK_RUNNING);
2211 /* Deal with packet mode. */
2212 if (packet && b == buf) {
2213 if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
2221 if (ldata->icanon && !L_EXTPROC(tty)) {
2222 retval = canon_copy_from_read_buf(tty, &b, &nr);
2223 if (retval == -EAGAIN) {
2230 /* The copy function takes the read lock and handles
2231 locking internally for this case */
2232 uncopied = copy_from_read_buf(tty, &b, &nr);
2233 uncopied += copy_from_read_buf(tty, &b, &nr);
2240 n_tty_check_unthrottle(tty);
2242 if (b - buf >= minimum)
2247 mutex_unlock(&ldata->atomic_read_lock);
2248 remove_wait_queue(&tty->read_wait, &wait);
2250 if (!waitqueue_active(&tty->read_wait))
2251 ldata->minimum_to_wake = minimum;
2253 __set_current_state(TASK_RUNNING);
2257 n_tty_set_room(tty);
2258 up_read(&tty->termios_rwsem);
2263 * n_tty_write - write function for tty
2265 * @file: file object
2266 * @buf: userspace buffer pointer
2269 * Write function of the terminal device. This is serialized with
2270 * respect to other write callers but not to termios changes, reads
2271 * and other such events. Since the receive code will echo characters,
2272 * thus calling driver write methods, the output_lock is used in
2273 * the output processing functions called here as well as in the
2274 * echo processing function to protect the column state and space
2275 * left in the buffer.
2277 * This code must be sure never to sleep through a hangup.
2279 * Locking: output_lock to protect column state and space left
2280 * (note that the process_output*() functions take this
2284 static ssize_t n_tty_write(struct tty_struct *tty, struct file *file,
2285 const unsigned char *buf, size_t nr)
2287 const unsigned char *b = buf;
2288 DECLARE_WAITQUEUE(wait, current);
2292 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */
2293 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) {
2294 retval = tty_check_change(tty);
2299 down_read(&tty->termios_rwsem);
2301 /* Write out any echoed characters that are still pending */
2302 process_echoes(tty);
2304 add_wait_queue(&tty->write_wait, &wait);
2306 set_current_state(TASK_INTERRUPTIBLE);
2307 if (signal_pending(current)) {
2308 retval = -ERESTARTSYS;
2311 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) {
2317 ssize_t num = process_output_block(tty, b, nr);
2329 if (process_output(c, tty) < 0)
2333 if (tty->ops->flush_chars)
2334 tty->ops->flush_chars(tty);
2337 c = tty->ops->write(tty, b, nr);
2350 if (file->f_flags & O_NONBLOCK) {
2354 up_read(&tty->termios_rwsem);
2358 down_read(&tty->termios_rwsem);
2361 __set_current_state(TASK_RUNNING);
2362 remove_wait_queue(&tty->write_wait, &wait);
2363 if (b - buf != nr && tty->fasync)
2364 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2365 up_read(&tty->termios_rwsem);
2366 return (b - buf) ? b - buf : retval;
2370 * n_tty_poll - poll method for N_TTY
2371 * @tty: terminal device
2372 * @file: file accessing it
2375 * Called when the line discipline is asked to poll() for data or
2376 * for special events. This code is not serialized with respect to
2377 * other events save open/close.
2379 * This code must be sure never to sleep through a hangup.
2380 * Called without the kernel lock held - fine
2383 static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
2386 struct n_tty_data *ldata = tty->disc_data;
2387 unsigned int mask = 0;
2389 poll_wait(file, &tty->read_wait, wait);
2390 poll_wait(file, &tty->write_wait, wait);
2391 if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty)))
2392 mask |= POLLIN | POLLRDNORM;
2393 if (tty->packet && tty->link->ctrl_status)
2394 mask |= POLLPRI | POLLIN | POLLRDNORM;
2395 if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
2397 if (tty_hung_up_p(file))
2399 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {
2400 if (MIN_CHAR(tty) && !TIME_CHAR(tty))
2401 ldata->minimum_to_wake = MIN_CHAR(tty);
2403 ldata->minimum_to_wake = 1;
2405 if (tty->ops->write && !tty_is_writelocked(tty) &&
2406 tty_chars_in_buffer(tty) < WAKEUP_CHARS &&
2407 tty_write_room(tty) > 0)
2408 mask |= POLLOUT | POLLWRNORM;
2412 static unsigned long inq_canon(struct n_tty_data *ldata)
2414 size_t nr, head, tail;
2416 if (ldata->canon_head == ldata->read_tail)
2418 head = ldata->canon_head;
2419 tail = ldata->read_tail;
2421 /* Skip EOF-chars.. */
2422 while (head != tail) {
2423 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) &&
2424 read_buf(ldata, tail) == __DISABLED_CHAR)
2431 static int n_tty_ioctl(struct tty_struct *tty, struct file *file,
2432 unsigned int cmd, unsigned long arg)
2434 struct n_tty_data *ldata = tty->disc_data;
2439 return put_user(tty_chars_in_buffer(tty), (int __user *) arg);
2441 down_write(&tty->termios_rwsem);
2443 retval = inq_canon(ldata);
2445 retval = read_cnt(ldata);
2446 up_write(&tty->termios_rwsem);
2447 return put_user(retval, (unsigned int __user *) arg);
2449 return n_tty_ioctl_helper(tty, file, cmd, arg);
2453 static void n_tty_fasync(struct tty_struct *tty, int on)
2455 struct n_tty_data *ldata = tty->disc_data;
2457 if (!waitqueue_active(&tty->read_wait)) {
2459 ldata->minimum_to_wake = 1;
2460 else if (!tty->fasync)
2461 ldata->minimum_to_wake = N_TTY_BUF_SIZE;
2465 struct tty_ldisc_ops tty_ldisc_N_TTY = {
2466 .magic = TTY_LDISC_MAGIC,
2469 .close = n_tty_close,
2470 .flush_buffer = n_tty_flush_buffer,
2471 .chars_in_buffer = n_tty_chars_in_buffer,
2473 .write = n_tty_write,
2474 .ioctl = n_tty_ioctl,
2475 .set_termios = n_tty_set_termios,
2477 .receive_buf = n_tty_receive_buf,
2478 .write_wakeup = n_tty_write_wakeup,
2479 .fasync = n_tty_fasync,
2480 .receive_buf2 = n_tty_receive_buf2,
2484 * n_tty_inherit_ops - inherit N_TTY methods
2485 * @ops: struct tty_ldisc_ops where to save N_TTY methods
2487 * Enables a 'subclass' line discipline to 'inherit' N_TTY
2491 void n_tty_inherit_ops(struct tty_ldisc_ops *ops)
2493 *ops = tty_ldisc_N_TTY;
2495 ops->refcount = ops->flags = 0;
2497 EXPORT_SYMBOL_GPL(n_tty_inherit_ops);