| /* |
| * n_tty.c --- implements the N_TTY line discipline. |
| * |
| * This code used to be in tty_io.c, but things are getting hairy |
| * enough that it made sense to split things off. (The N_TTY |
| * processing has changed so much that it's hardly recognizable, |
| * anyway...) |
| * |
| * Note that the open routine for N_TTY is guaranteed never to return |
| * an error. This is because Linux will fall back to setting a line |
| * to N_TTY if it can not switch to any other line discipline. |
| * |
| * Written by Theodore Ts'o, Copyright 1994. |
| * |
| * This file also contains code originally written by Linus Torvalds, |
| * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994. |
| * |
| * This file may be redistributed under the terms of the GNU General Public |
| * License. |
| * |
| * Reduced memory usage for older ARM systems - Russell King. |
| * |
| * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of |
| * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu> |
| * who actually finally proved there really was a race. |
| * |
| * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to |
| * waiting writing processes-Sapan Bhatia <sapan@corewars.org>. |
| * Also fixed a bug in BLOCKING mode where n_tty_write returns |
| * EAGAIN |
| */ |
| |
| #include <linux/types.h> |
| #include <linux/major.h> |
| #include <linux/errno.h> |
| #include <linux/signal.h> |
| #include <linux/fcntl.h> |
| #include <linux/sched.h> |
| #include <linux/interrupt.h> |
| #include <linux/tty.h> |
| #include <linux/timer.h> |
| #include <linux/ctype.h> |
| #include <linux/mm.h> |
| #include <linux/string.h> |
| #include <linux/slab.h> |
| #include <linux/poll.h> |
| #include <linux/bitops.h> |
| #include <linux/audit.h> |
| #include <linux/file.h> |
| #include <linux/uaccess.h> |
| #include <linux/module.h> |
| #include <linux/ratelimit.h> |
| |
| |
| /* number of characters left in xmit buffer before select has we have room */ |
| #define WAKEUP_CHARS 256 |
| |
| /* |
| * This defines the low- and high-watermarks for throttling and |
| * unthrottling the TTY driver. These watermarks are used for |
| * controlling the space in the read buffer. |
| */ |
| #define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ |
| #define TTY_THRESHOLD_UNTHROTTLE 128 |
| |
| /* |
| * Special byte codes used in the echo buffer to represent operations |
| * or special handling of characters. Bytes in the echo buffer that |
| * are not part of such special blocks are treated as normal character |
| * codes. |
| */ |
| #define ECHO_OP_START 0xff |
| #define ECHO_OP_MOVE_BACK_COL 0x80 |
| #define ECHO_OP_SET_CANON_COL 0x81 |
| #define ECHO_OP_ERASE_TAB 0x82 |
| |
| struct n_tty_data { |
| unsigned int column; |
| unsigned long overrun_time; |
| int num_overrun; |
| |
| unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1; |
| unsigned char echo_overrun:1; |
| |
| DECLARE_BITMAP(process_char_map, 256); |
| DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE); |
| |
| char *read_buf; |
| int read_head; |
| int read_tail; |
| int read_cnt; |
| |
| unsigned char *echo_buf; |
| unsigned int echo_pos; |
| unsigned int echo_cnt; |
| |
| int canon_data; |
| unsigned long canon_head; |
| unsigned int canon_column; |
| |
| struct mutex atomic_read_lock; |
| struct mutex output_lock; |
| struct mutex echo_lock; |
| raw_spinlock_t read_lock; |
| }; |
| |
| static inline int tty_put_user(struct tty_struct *tty, unsigned char x, |
| unsigned char __user *ptr) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| tty_audit_add_data(tty, &x, 1, ldata->icanon); |
| return put_user(x, ptr); |
| } |
| |
| /** |
| * n_tty_set__room - receive space |
| * @tty: terminal |
| * |
| * Called by the driver to find out how much data it is |
| * permitted to feed to the line discipline without any being lost |
| * and thus to manage flow control. Not serialized. Answers for the |
| * "instant". |
| */ |
| |
| static void n_tty_set_room(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int left; |
| int old_left; |
| |
| /* ldata->read_cnt is not read locked ? */ |
| if (I_PARMRK(tty)) { |
| /* Multiply read_cnt by 3, since each byte might take up to |
| * three times as many spaces when PARMRK is set (depending on |
| * its flags, e.g. parity error). */ |
| left = N_TTY_BUF_SIZE - ldata->read_cnt * 3 - 1; |
| } else |
| left = N_TTY_BUF_SIZE - ldata->read_cnt - 1; |
| |
| /* |
| * If we are doing input canonicalization, and there are no |
| * pending newlines, let characters through without limit, so |
| * that erase characters will be handled. Other excess |
| * characters will be beeped. |
| */ |
| if (left <= 0) |
| left = ldata->icanon && !ldata->canon_data; |
| old_left = tty->receive_room; |
| tty->receive_room = left; |
| |
| /* Did this open up the receive buffer? We may need to flip */ |
| if (left && !old_left) { |
| WARN_RATELIMIT(tty->port->itty == NULL, |
| "scheduling with invalid itty\n"); |
| /* see if ldisc has been killed - if so, this means that |
| * even though the ldisc has been halted and ->buf.work |
| * cancelled, ->buf.work is about to be rescheduled |
| */ |
| WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags), |
| "scheduling buffer work for halted ldisc\n"); |
| schedule_work(&tty->port->buf.work); |
| } |
| } |
| |
| static void put_tty_queue_nolock(unsigned char c, struct n_tty_data *ldata) |
| { |
| if (ldata->read_cnt < N_TTY_BUF_SIZE) { |
| ldata->read_buf[ldata->read_head] = c; |
| ldata->read_head = (ldata->read_head + 1) & (N_TTY_BUF_SIZE-1); |
| ldata->read_cnt++; |
| } |
| } |
| |
| /** |
| * put_tty_queue - add character to tty |
| * @c: character |
| * @ldata: n_tty data |
| * |
| * Add a character to the tty read_buf queue. This is done under the |
| * read_lock to serialize character addition and also to protect us |
| * against parallel reads or flushes |
| */ |
| |
| static void put_tty_queue(unsigned char c, struct n_tty_data *ldata) |
| { |
| unsigned long flags; |
| /* |
| * The problem of stomping on the buffers ends here. |
| * Why didn't anyone see this one coming? --AJK |
| */ |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| put_tty_queue_nolock(c, ldata); |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| } |
| |
| /** |
| * reset_buffer_flags - reset buffer state |
| * @tty: terminal to reset |
| * |
| * Reset the read buffer counters and clear the flags. |
| * Called from n_tty_open() and n_tty_flush_buffer(). |
| * |
| * Locking: tty_read_lock for read fields. |
| */ |
| |
| static void reset_buffer_flags(struct n_tty_data *ldata) |
| { |
| unsigned long flags; |
| |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| ldata->read_head = ldata->read_tail = ldata->read_cnt = 0; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| |
| mutex_lock(&ldata->echo_lock); |
| ldata->echo_pos = ldata->echo_cnt = ldata->echo_overrun = 0; |
| mutex_unlock(&ldata->echo_lock); |
| |
| ldata->canon_head = ldata->canon_data = ldata->erasing = 0; |
| bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); |
| } |
| |
| static void n_tty_packet_mode_flush(struct tty_struct *tty) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&tty->ctrl_lock, flags); |
| if (tty->link->packet) { |
| tty->ctrl_status |= TIOCPKT_FLUSHREAD; |
| wake_up_interruptible(&tty->link->read_wait); |
| } |
| spin_unlock_irqrestore(&tty->ctrl_lock, flags); |
| } |
| |
| /** |
| * n_tty_flush_buffer - clean input queue |
| * @tty: terminal device |
| * |
| * Flush the input buffer. Called when the tty layer wants the |
| * buffer flushed (eg at hangup) or when the N_TTY line discipline |
| * internally has to clean the pending queue (for example some signals). |
| * |
| * Locking: ctrl_lock, read_lock. |
| */ |
| |
| static void n_tty_flush_buffer(struct tty_struct *tty) |
| { |
| reset_buffer_flags(tty->disc_data); |
| n_tty_set_room(tty); |
| |
| if (tty->link) |
| n_tty_packet_mode_flush(tty); |
| } |
| |
| /** |
| * n_tty_chars_in_buffer - report available bytes |
| * @tty: tty device |
| * |
| * Report the number of characters buffered to be delivered to user |
| * at this instant in time. |
| * |
| * Locking: read_lock |
| */ |
| |
| static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| unsigned long flags; |
| ssize_t n = 0; |
| |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| if (!ldata->icanon) { |
| n = ldata->read_cnt; |
| } else if (ldata->canon_data) { |
| n = (ldata->canon_head > ldata->read_tail) ? |
| ldata->canon_head - ldata->read_tail : |
| ldata->canon_head + (N_TTY_BUF_SIZE - ldata->read_tail); |
| } |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| return n; |
| } |
| |
| /** |
| * is_utf8_continuation - utf8 multibyte check |
| * @c: byte to check |
| * |
| * Returns true if the utf8 character 'c' is a multibyte continuation |
| * character. We use this to correctly compute the on screen size |
| * of the character when printing |
| */ |
| |
| static inline int is_utf8_continuation(unsigned char c) |
| { |
| return (c & 0xc0) == 0x80; |
| } |
| |
| /** |
| * is_continuation - multibyte check |
| * @c: byte to check |
| * |
| * Returns true if the utf8 character 'c' is a multibyte continuation |
| * character and the terminal is in unicode mode. |
| */ |
| |
| static inline int is_continuation(unsigned char c, struct tty_struct *tty) |
| { |
| return I_IUTF8(tty) && is_utf8_continuation(c); |
| } |
| |
| /** |
| * do_output_char - output one character |
| * @c: character (or partial unicode symbol) |
| * @tty: terminal device |
| * @space: space available in tty driver write buffer |
| * |
| * This is a helper function that handles one output character |
| * (including special characters like TAB, CR, LF, etc.), |
| * doing OPOST processing and putting the results in the |
| * tty driver's write buffer. |
| * |
| * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY |
| * and NLDLY. They simply aren't relevant in the world today. |
| * If you ever need them, add them here. |
| * |
| * Returns the number of bytes of buffer space used or -1 if |
| * no space left. |
| * |
| * Locking: should be called under the output_lock to protect |
| * the column state and space left in the buffer |
| */ |
| |
| static int do_output_char(unsigned char c, struct tty_struct *tty, int space) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int spaces; |
| |
| if (!space) |
| return -1; |
| |
| switch (c) { |
| case '\n': |
| if (O_ONLRET(tty)) |
| ldata->column = 0; |
| if (O_ONLCR(tty)) { |
| if (space < 2) |
| return -1; |
| ldata->canon_column = ldata->column = 0; |
| tty->ops->write(tty, "\r\n", 2); |
| return 2; |
| } |
| ldata->canon_column = ldata->column; |
| break; |
| case '\r': |
| if (O_ONOCR(tty) && ldata->column == 0) |
| return 0; |
| if (O_OCRNL(tty)) { |
| c = '\n'; |
| if (O_ONLRET(tty)) |
| ldata->canon_column = ldata->column = 0; |
| break; |
| } |
| ldata->canon_column = ldata->column = 0; |
| break; |
| case '\t': |
| spaces = 8 - (ldata->column & 7); |
| if (O_TABDLY(tty) == XTABS) { |
| if (space < spaces) |
| return -1; |
| ldata->column += spaces; |
| tty->ops->write(tty, " ", spaces); |
| return spaces; |
| } |
| ldata->column += spaces; |
| break; |
| case '\b': |
| if (ldata->column > 0) |
| ldata->column--; |
| break; |
| default: |
| if (!iscntrl(c)) { |
| if (O_OLCUC(tty)) |
| c = toupper(c); |
| if (!is_continuation(c, tty)) |
| ldata->column++; |
| } |
| break; |
| } |
| |
| tty_put_char(tty, c); |
| return 1; |
| } |
| |
| /** |
| * process_output - output post processor |
| * @c: character (or partial unicode symbol) |
| * @tty: terminal device |
| * |
| * Output one character with OPOST processing. |
| * Returns -1 when the output device is full and the character |
| * must be retried. |
| * |
| * Locking: output_lock to protect column state and space left |
| * (also, this is called from n_tty_write under the |
| * tty layer write lock) |
| */ |
| |
| static int process_output(unsigned char c, struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int space, retval; |
| |
| mutex_lock(&ldata->output_lock); |
| |
| space = tty_write_room(tty); |
| retval = do_output_char(c, tty, space); |
| |
| mutex_unlock(&ldata->output_lock); |
| if (retval < 0) |
| return -1; |
| else |
| return 0; |
| } |
| |
| /** |
| * process_output_block - block post processor |
| * @tty: terminal device |
| * @buf: character buffer |
| * @nr: number of bytes to output |
| * |
| * Output a block of characters with OPOST processing. |
| * Returns the number of characters output. |
| * |
| * This path is used to speed up block console writes, among other |
| * things when processing blocks of output data. It handles only |
| * the simple cases normally found and helps to generate blocks of |
| * symbols for the console driver and thus improve performance. |
| * |
| * Locking: output_lock to protect column state and space left |
| * (also, this is called from n_tty_write under the |
| * tty layer write lock) |
| */ |
| |
| static ssize_t process_output_block(struct tty_struct *tty, |
| const unsigned char *buf, unsigned int nr) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int space; |
| int i; |
| const unsigned char *cp; |
| |
| mutex_lock(&ldata->output_lock); |
| |
| space = tty_write_room(tty); |
| if (!space) { |
| mutex_unlock(&ldata->output_lock); |
| return 0; |
| } |
| if (nr > space) |
| nr = space; |
| |
| for (i = 0, cp = buf; i < nr; i++, cp++) { |
| unsigned char c = *cp; |
| |
| switch (c) { |
| case '\n': |
| if (O_ONLRET(tty)) |
| ldata->column = 0; |
| if (O_ONLCR(tty)) |
| goto break_out; |
| ldata->canon_column = ldata->column; |
| break; |
| case '\r': |
| if (O_ONOCR(tty) && ldata->column == 0) |
| goto break_out; |
| if (O_OCRNL(tty)) |
| goto break_out; |
| ldata->canon_column = ldata->column = 0; |
| break; |
| case '\t': |
| goto break_out; |
| case '\b': |
| if (ldata->column > 0) |
| ldata->column--; |
| break; |
| default: |
| if (!iscntrl(c)) { |
| if (O_OLCUC(tty)) |
| goto break_out; |
| if (!is_continuation(c, tty)) |
| ldata->column++; |
| } |
| break; |
| } |
| } |
| break_out: |
| i = tty->ops->write(tty, buf, i); |
| |
| mutex_unlock(&ldata->output_lock); |
| return i; |
| } |
| |
| /** |
| * process_echoes - write pending echo characters |
| * @tty: terminal device |
| * |
| * Write previously buffered echo (and other ldisc-generated) |
| * characters to the tty. |
| * |
| * Characters generated by the ldisc (including echoes) need to |
| * be buffered because the driver's write buffer can fill during |
| * heavy program output. Echoing straight to the driver will |
| * often fail under these conditions, causing lost characters and |
| * resulting mismatches of ldisc state information. |
| * |
| * Since the ldisc state must represent the characters actually sent |
| * to the driver at the time of the write, operations like certain |
| * changes in column state are also saved in the buffer and executed |
| * here. |
| * |
| * A circular fifo buffer is used so that the most recent characters |
| * are prioritized. Also, when control characters are echoed with a |
| * prefixed "^", the pair is treated atomically and thus not separated. |
| * |
| * Locking: output_lock to protect column state and space left, |
| * echo_lock to protect the echo buffer |
| */ |
| |
| static void process_echoes(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int space, nr; |
| unsigned char c; |
| unsigned char *cp, *buf_end; |
| |
| if (!ldata->echo_cnt) |
| return; |
| |
| mutex_lock(&ldata->output_lock); |
| mutex_lock(&ldata->echo_lock); |
| |
| space = tty_write_room(tty); |
| |
| buf_end = ldata->echo_buf + N_TTY_BUF_SIZE; |
| cp = ldata->echo_buf + ldata->echo_pos; |
| nr = ldata->echo_cnt; |
| while (nr > 0) { |
| c = *cp; |
| if (c == ECHO_OP_START) { |
| unsigned char op; |
| unsigned char *opp; |
| int no_space_left = 0; |
| |
| /* |
| * If the buffer byte is the start of a multi-byte |
| * operation, get the next byte, which is either the |
| * op code or a control character value. |
| */ |
| opp = cp + 1; |
| if (opp == buf_end) |
| opp -= N_TTY_BUF_SIZE; |
| op = *opp; |
| |
| switch (op) { |
| unsigned int num_chars, num_bs; |
| |
| case ECHO_OP_ERASE_TAB: |
| if (++opp == buf_end) |
| opp -= N_TTY_BUF_SIZE; |
| num_chars = *opp; |
| |
| /* |
| * Determine how many columns to go back |
| * in order to erase the tab. |
| * This depends on the number of columns |
| * used by other characters within the tab |
| * area. If this (modulo 8) count is from |
| * the start of input rather than from a |
| * previous tab, we offset by canon column. |
| * Otherwise, tab spacing is normal. |
| */ |
| if (!(num_chars & 0x80)) |
| num_chars += ldata->canon_column; |
| num_bs = 8 - (num_chars & 7); |
| |
| if (num_bs > space) { |
| no_space_left = 1; |
| break; |
| } |
| space -= num_bs; |
| while (num_bs--) { |
| tty_put_char(tty, '\b'); |
| if (ldata->column > 0) |
| ldata->column--; |
| } |
| cp += 3; |
| nr -= 3; |
| break; |
| |
| case ECHO_OP_SET_CANON_COL: |
| ldata->canon_column = ldata->column; |
| cp += 2; |
| nr -= 2; |
| break; |
| |
| case ECHO_OP_MOVE_BACK_COL: |
| if (ldata->column > 0) |
| ldata->column--; |
| cp += 2; |
| nr -= 2; |
| break; |
| |
| case ECHO_OP_START: |
| /* This is an escaped echo op start code */ |
| if (!space) { |
| no_space_left = 1; |
| break; |
| } |
| tty_put_char(tty, ECHO_OP_START); |
| ldata->column++; |
| space--; |
| cp += 2; |
| nr -= 2; |
| break; |
| |
| default: |
| /* |
| * If the op is not a special byte code, |
| * it is a ctrl char tagged to be echoed |
| * as "^X" (where X is the letter |
| * representing the control char). |
| * Note that we must ensure there is |
| * enough space for the whole ctrl pair. |
| * |
| */ |
| if (space < 2) { |
| no_space_left = 1; |
| break; |
| } |
| tty_put_char(tty, '^'); |
| tty_put_char(tty, op ^ 0100); |
| ldata->column += 2; |
| space -= 2; |
| cp += 2; |
| nr -= 2; |
| } |
| |
| if (no_space_left) |
| break; |
| } else { |
| if (O_OPOST(tty) && |
| !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { |
| int retval = do_output_char(c, tty, space); |
| if (retval < 0) |
| break; |
| space -= retval; |
| } else { |
| if (!space) |
| break; |
| tty_put_char(tty, c); |
| space -= 1; |
| } |
| cp += 1; |
| nr -= 1; |
| } |
| |
| /* When end of circular buffer reached, wrap around */ |
| if (cp >= buf_end) |
| cp -= N_TTY_BUF_SIZE; |
| } |
| |
| if (nr == 0) { |
| ldata->echo_pos = 0; |
| ldata->echo_cnt = 0; |
| ldata->echo_overrun = 0; |
| } else { |
| int num_processed = ldata->echo_cnt - nr; |
| ldata->echo_pos += num_processed; |
| ldata->echo_pos &= N_TTY_BUF_SIZE - 1; |
| ldata->echo_cnt = nr; |
| if (num_processed > 0) |
| ldata->echo_overrun = 0; |
| } |
| |
| mutex_unlock(&ldata->echo_lock); |
| mutex_unlock(&ldata->output_lock); |
| |
| if (tty->ops->flush_chars) |
| tty->ops->flush_chars(tty); |
| } |
| |
| /** |
| * add_echo_byte - add a byte to the echo buffer |
| * @c: unicode byte to echo |
| * @ldata: n_tty data |
| * |
| * Add a character or operation byte to the echo buffer. |
| * |
| * Should be called under the echo lock to protect the echo buffer. |
| */ |
| |
| static void add_echo_byte(unsigned char c, struct n_tty_data *ldata) |
| { |
| int new_byte_pos; |
| |
| if (ldata->echo_cnt == N_TTY_BUF_SIZE) { |
| /* Circular buffer is already at capacity */ |
| new_byte_pos = ldata->echo_pos; |
| |
| /* |
| * Since the buffer start position needs to be advanced, |
| * be sure to step by a whole operation byte group. |
| */ |
| if (ldata->echo_buf[ldata->echo_pos] == ECHO_OP_START) { |
| if (ldata->echo_buf[(ldata->echo_pos + 1) & |
| (N_TTY_BUF_SIZE - 1)] == |
| ECHO_OP_ERASE_TAB) { |
| ldata->echo_pos += 3; |
| ldata->echo_cnt -= 2; |
| } else { |
| ldata->echo_pos += 2; |
| ldata->echo_cnt -= 1; |
| } |
| } else { |
| ldata->echo_pos++; |
| } |
| ldata->echo_pos &= N_TTY_BUF_SIZE - 1; |
| |
| ldata->echo_overrun = 1; |
| } else { |
| new_byte_pos = ldata->echo_pos + ldata->echo_cnt; |
| new_byte_pos &= N_TTY_BUF_SIZE - 1; |
| ldata->echo_cnt++; |
| } |
| |
| ldata->echo_buf[new_byte_pos] = c; |
| } |
| |
| /** |
| * echo_move_back_col - add operation to move back a column |
| * @ldata: n_tty data |
| * |
| * Add an operation to the echo buffer to move back one column. |
| * |
| * Locking: echo_lock to protect the echo buffer |
| */ |
| |
| static void echo_move_back_col(struct n_tty_data *ldata) |
| { |
| mutex_lock(&ldata->echo_lock); |
| add_echo_byte(ECHO_OP_START, ldata); |
| add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata); |
| mutex_unlock(&ldata->echo_lock); |
| } |
| |
| /** |
| * echo_set_canon_col - add operation to set the canon column |
| * @ldata: n_tty data |
| * |
| * Add an operation to the echo buffer to set the canon column |
| * to the current column. |
| * |
| * Locking: echo_lock to protect the echo buffer |
| */ |
| |
| static void echo_set_canon_col(struct n_tty_data *ldata) |
| { |
| mutex_lock(&ldata->echo_lock); |
| add_echo_byte(ECHO_OP_START, ldata); |
| add_echo_byte(ECHO_OP_SET_CANON_COL, ldata); |
| mutex_unlock(&ldata->echo_lock); |
| } |
| |
| /** |
| * echo_erase_tab - add operation to erase a tab |
| * @num_chars: number of character columns already used |
| * @after_tab: true if num_chars starts after a previous tab |
| * @ldata: n_tty data |
| * |
| * Add an operation to the echo buffer to erase a tab. |
| * |
| * Called by the eraser function, which knows how many character |
| * columns have been used since either a previous tab or the start |
| * of input. This information will be used later, along with |
| * canon column (if applicable), to go back the correct number |
| * of columns. |
| * |
| * Locking: echo_lock to protect the echo buffer |
| */ |
| |
| static void echo_erase_tab(unsigned int num_chars, int after_tab, |
| struct n_tty_data *ldata) |
| { |
| mutex_lock(&ldata->echo_lock); |
| |
| add_echo_byte(ECHO_OP_START, ldata); |
| add_echo_byte(ECHO_OP_ERASE_TAB, ldata); |
| |
| /* We only need to know this modulo 8 (tab spacing) */ |
| num_chars &= 7; |
| |
| /* Set the high bit as a flag if num_chars is after a previous tab */ |
| if (after_tab) |
| num_chars |= 0x80; |
| |
| add_echo_byte(num_chars, ldata); |
| |
| mutex_unlock(&ldata->echo_lock); |
| } |
| |
| /** |
| * echo_char_raw - echo a character raw |
| * @c: unicode byte to echo |
| * @tty: terminal device |
| * |
| * Echo user input back onto the screen. This must be called only when |
| * L_ECHO(tty) is true. Called from the driver receive_buf path. |
| * |
| * This variant does not treat control characters specially. |
| * |
| * Locking: echo_lock to protect the echo buffer |
| */ |
| |
| static void echo_char_raw(unsigned char c, struct n_tty_data *ldata) |
| { |
| mutex_lock(&ldata->echo_lock); |
| if (c == ECHO_OP_START) { |
| add_echo_byte(ECHO_OP_START, ldata); |
| add_echo_byte(ECHO_OP_START, ldata); |
| } else { |
| add_echo_byte(c, ldata); |
| } |
| mutex_unlock(&ldata->echo_lock); |
| } |
| |
| /** |
| * echo_char - echo a character |
| * @c: unicode byte to echo |
| * @tty: terminal device |
| * |
| * Echo user input back onto the screen. This must be called only when |
| * L_ECHO(tty) is true. Called from the driver receive_buf path. |
| * |
| * This variant tags control characters to be echoed as "^X" |
| * (where X is the letter representing the control char). |
| * |
| * Locking: echo_lock to protect the echo buffer |
| */ |
| |
| static void echo_char(unsigned char c, struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| mutex_lock(&ldata->echo_lock); |
| |
| if (c == ECHO_OP_START) { |
| add_echo_byte(ECHO_OP_START, ldata); |
| add_echo_byte(ECHO_OP_START, ldata); |
| } else { |
| if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') |
| add_echo_byte(ECHO_OP_START, ldata); |
| add_echo_byte(c, ldata); |
| } |
| |
| mutex_unlock(&ldata->echo_lock); |
| } |
| |
| /** |
| * finish_erasing - complete erase |
| * @ldata: n_tty data |
| */ |
| |
| static inline void finish_erasing(struct n_tty_data *ldata) |
| { |
| if (ldata->erasing) { |
| echo_char_raw('/', ldata); |
| ldata->erasing = 0; |
| } |
| } |
| |
| /** |
| * eraser - handle erase function |
| * @c: character input |
| * @tty: terminal device |
| * |
| * Perform erase and necessary output when an erase character is |
| * present in the stream from the driver layer. Handles the complexities |
| * of UTF-8 multibyte symbols. |
| * |
| * Locking: read_lock for tty buffers |
| */ |
| |
| static void eraser(unsigned char c, struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| enum { ERASE, WERASE, KILL } kill_type; |
| int head, seen_alnums, cnt; |
| unsigned long flags; |
| |
| /* FIXME: locking needed ? */ |
| if (ldata->read_head == ldata->canon_head) { |
| /* process_output('\a', tty); */ /* what do you think? */ |
| return; |
| } |
| if (c == ERASE_CHAR(tty)) |
| kill_type = ERASE; |
| else if (c == WERASE_CHAR(tty)) |
| kill_type = WERASE; |
| else { |
| if (!L_ECHO(tty)) { |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) & |
| (N_TTY_BUF_SIZE - 1)); |
| ldata->read_head = ldata->canon_head; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| return; |
| } |
| if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) & |
| (N_TTY_BUF_SIZE - 1)); |
| ldata->read_head = ldata->canon_head; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| finish_erasing(ldata); |
| echo_char(KILL_CHAR(tty), tty); |
| /* Add a newline if ECHOK is on and ECHOKE is off. */ |
| if (L_ECHOK(tty)) |
| echo_char_raw('\n', ldata); |
| return; |
| } |
| kill_type = KILL; |
| } |
| |
| seen_alnums = 0; |
| /* FIXME: Locking ?? */ |
| while (ldata->read_head != ldata->canon_head) { |
| head = ldata->read_head; |
| |
| /* erase a single possibly multibyte character */ |
| do { |
| head = (head - 1) & (N_TTY_BUF_SIZE-1); |
| c = ldata->read_buf[head]; |
| } while (is_continuation(c, tty) && head != ldata->canon_head); |
| |
| /* do not partially erase */ |
| if (is_continuation(c, tty)) |
| break; |
| |
| if (kill_type == WERASE) { |
| /* Equivalent to BSD's ALTWERASE. */ |
| if (isalnum(c) || c == '_') |
| seen_alnums++; |
| else if (seen_alnums) |
| break; |
| } |
| cnt = (ldata->read_head - head) & (N_TTY_BUF_SIZE-1); |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| ldata->read_head = head; |
| ldata->read_cnt -= cnt; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| if (L_ECHO(tty)) { |
| if (L_ECHOPRT(tty)) { |
| if (!ldata->erasing) { |
| echo_char_raw('\\', ldata); |
| ldata->erasing = 1; |
| } |
| /* if cnt > 1, output a multi-byte character */ |
| echo_char(c, tty); |
| while (--cnt > 0) { |
| head = (head+1) & (N_TTY_BUF_SIZE-1); |
| echo_char_raw(ldata->read_buf[head], |
| ldata); |
| echo_move_back_col(ldata); |
| } |
| } else if (kill_type == ERASE && !L_ECHOE(tty)) { |
| echo_char(ERASE_CHAR(tty), tty); |
| } else if (c == '\t') { |
| unsigned int num_chars = 0; |
| int after_tab = 0; |
| unsigned long tail = ldata->read_head; |
| |
| /* |
| * Count the columns used for characters |
| * since the start of input or after a |
| * previous tab. |
| * This info is used to go back the correct |
| * number of columns. |
| */ |
| while (tail != ldata->canon_head) { |
| tail = (tail-1) & (N_TTY_BUF_SIZE-1); |
| c = ldata->read_buf[tail]; |
| if (c == '\t') { |
| after_tab = 1; |
| break; |
| } else if (iscntrl(c)) { |
| if (L_ECHOCTL(tty)) |
| num_chars += 2; |
| } else if (!is_continuation(c, tty)) { |
| num_chars++; |
| } |
| } |
| echo_erase_tab(num_chars, after_tab, ldata); |
| } else { |
| if (iscntrl(c) && L_ECHOCTL(tty)) { |
| echo_char_raw('\b', ldata); |
| echo_char_raw(' ', ldata); |
| echo_char_raw('\b', ldata); |
| } |
| if (!iscntrl(c) || L_ECHOCTL(tty)) { |
| echo_char_raw('\b', ldata); |
| echo_char_raw(' ', ldata); |
| echo_char_raw('\b', ldata); |
| } |
| } |
| } |
| if (kill_type == ERASE) |
| break; |
| } |
| if (ldata->read_head == ldata->canon_head && L_ECHO(tty)) |
| finish_erasing(ldata); |
| } |
| |
| /** |
| * isig - handle the ISIG optio |
| * @sig: signal |
| * @tty: terminal |
| * |
| * Called when a signal is being sent due to terminal input. |
| * Called from the driver receive_buf path so serialized. |
| * |
| * Locking: ctrl_lock |
| */ |
| |
| static inline void isig(int sig, struct tty_struct *tty) |
| { |
| struct pid *tty_pgrp = tty_get_pgrp(tty); |
| if (tty_pgrp) { |
| kill_pgrp(tty_pgrp, sig, 1); |
| put_pid(tty_pgrp); |
| } |
| } |
| |
| /** |
| * n_tty_receive_break - handle break |
| * @tty: terminal |
| * |
| * An RS232 break event has been hit in the incoming bitstream. This |
| * can cause a variety of events depending upon the termios settings. |
| * |
| * Called from the receive_buf path so single threaded. |
| */ |
| |
| static inline void n_tty_receive_break(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| if (I_IGNBRK(tty)) |
| return; |
| if (I_BRKINT(tty)) { |
| isig(SIGINT, tty); |
| if (!L_NOFLSH(tty)) { |
| n_tty_flush_buffer(tty); |
| tty_driver_flush_buffer(tty); |
| } |
| return; |
| } |
| if (I_PARMRK(tty)) { |
| put_tty_queue('\377', ldata); |
| put_tty_queue('\0', ldata); |
| } |
| put_tty_queue('\0', ldata); |
| wake_up_interruptible(&tty->read_wait); |
| } |
| |
| /** |
| * n_tty_receive_overrun - handle overrun reporting |
| * @tty: terminal |
| * |
| * Data arrived faster than we could process it. While the tty |
| * driver has flagged this the bits that were missed are gone |
| * forever. |
| * |
| * Called from the receive_buf path so single threaded. Does not |
| * need locking as num_overrun and overrun_time are function |
| * private. |
| */ |
| |
| static inline void n_tty_receive_overrun(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| char buf[64]; |
| |
| ldata->num_overrun++; |
| if (time_after(jiffies, ldata->overrun_time + HZ) || |
| time_after(ldata->overrun_time, jiffies)) { |
| printk(KERN_WARNING "%s: %d input overrun(s)\n", |
| tty_name(tty, buf), |
| ldata->num_overrun); |
| ldata->overrun_time = jiffies; |
| ldata->num_overrun = 0; |
| } |
| } |
| |
| /** |
| * n_tty_receive_parity_error - error notifier |
| * @tty: terminal device |
| * @c: character |
| * |
| * Process a parity error and queue the right data to indicate |
| * the error case if necessary. Locking as per n_tty_receive_buf. |
| */ |
| static inline void n_tty_receive_parity_error(struct tty_struct *tty, |
| unsigned char c) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| if (I_IGNPAR(tty)) |
| return; |
| if (I_PARMRK(tty)) { |
| put_tty_queue('\377', ldata); |
| put_tty_queue('\0', ldata); |
| put_tty_queue(c, ldata); |
| } else if (I_INPCK(tty)) |
| put_tty_queue('\0', ldata); |
| else |
| put_tty_queue(c, ldata); |
| wake_up_interruptible(&tty->read_wait); |
| } |
| |
| /** |
| * n_tty_receive_char - perform processing |
| * @tty: terminal device |
| * @c: character |
| * |
| * Process an individual character of input received from the driver. |
| * This is serialized with respect to itself by the rules for the |
| * driver above. |
| */ |
| |
| static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| unsigned long flags; |
| int parmrk; |
| |
| if (ldata->raw) { |
| put_tty_queue(c, ldata); |
| return; |
| } |
| |
| if (I_ISTRIP(tty)) |
| c &= 0x7f; |
| if (I_IUCLC(tty) && L_IEXTEN(tty)) |
| c = tolower(c); |
| |
| if (L_EXTPROC(tty)) { |
| put_tty_queue(c, ldata); |
| return; |
| } |
| |
| if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && |
| I_IXANY(tty) && c != START_CHAR(tty) && c != STOP_CHAR(tty) && |
| c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && c != SUSP_CHAR(tty)) { |
| start_tty(tty); |
| process_echoes(tty); |
| } |
| |
| if (tty->closing) { |
| if (I_IXON(tty)) { |
| if (c == START_CHAR(tty)) { |
| start_tty(tty); |
| process_echoes(tty); |
| } else if (c == STOP_CHAR(tty)) |
| stop_tty(tty); |
| } |
| return; |
| } |
| |
| /* |
| * If the previous character was LNEXT, or we know that this |
| * character is not one of the characters that we'll have to |
| * handle specially, do shortcut processing to speed things |
| * up. |
| */ |
| if (!test_bit(c, ldata->process_char_map) || ldata->lnext) { |
| ldata->lnext = 0; |
| parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; |
| if (ldata->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) { |
| /* beep if no space */ |
| if (L_ECHO(tty)) |
| process_output('\a', tty); |
| return; |
| } |
| if (L_ECHO(tty)) { |
| finish_erasing(ldata); |
| /* Record the column of first canon char. */ |
| if (ldata->canon_head == ldata->read_head) |
| echo_set_canon_col(ldata); |
| echo_char(c, tty); |
| process_echoes(tty); |
| } |
| if (parmrk) |
| put_tty_queue(c, ldata); |
| put_tty_queue(c, ldata); |
| return; |
| } |
| |
| if (I_IXON(tty)) { |
| if (c == START_CHAR(tty)) { |
| start_tty(tty); |
| process_echoes(tty); |
| return; |
| } |
| if (c == STOP_CHAR(tty)) { |
| stop_tty(tty); |
| return; |
| } |
| } |
| |
| if (L_ISIG(tty)) { |
| int signal; |
| signal = SIGINT; |
| if (c == INTR_CHAR(tty)) |
| goto send_signal; |
| signal = SIGQUIT; |
| if (c == QUIT_CHAR(tty)) |
| goto send_signal; |
| signal = SIGTSTP; |
| if (c == SUSP_CHAR(tty)) { |
| send_signal: |
| if (!L_NOFLSH(tty)) { |
| n_tty_flush_buffer(tty); |
| tty_driver_flush_buffer(tty); |
| } |
| if (I_IXON(tty)) |
| start_tty(tty); |
| if (L_ECHO(tty)) { |
| echo_char(c, tty); |
| process_echoes(tty); |
| } |
| isig(signal, tty); |
| return; |
| } |
| } |
| |
| if (c == '\r') { |
| if (I_IGNCR(tty)) |
| return; |
| if (I_ICRNL(tty)) |
| c = '\n'; |
| } else if (c == '\n' && I_INLCR(tty)) |
| c = '\r'; |
| |
| if (ldata->icanon) { |
| if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || |
| (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { |
| eraser(c, tty); |
| process_echoes(tty); |
| return; |
| } |
| if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { |
| ldata->lnext = 1; |
| if (L_ECHO(tty)) { |
| finish_erasing(ldata); |
| if (L_ECHOCTL(tty)) { |
| echo_char_raw('^', ldata); |
| echo_char_raw('\b', ldata); |
| process_echoes(tty); |
| } |
| } |
| return; |
| } |
| if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && |
| L_IEXTEN(tty)) { |
| unsigned long tail = ldata->canon_head; |
| |
| finish_erasing(ldata); |
| echo_char(c, tty); |
| echo_char_raw('\n', ldata); |
| while (tail != ldata->read_head) { |
| echo_char(ldata->read_buf[tail], tty); |
| tail = (tail+1) & (N_TTY_BUF_SIZE-1); |
| } |
| process_echoes(tty); |
| return; |
| } |
| if (c == '\n') { |
| if (ldata->read_cnt >= N_TTY_BUF_SIZE) { |
| if (L_ECHO(tty)) |
| process_output('\a', tty); |
| return; |
| } |
| if (L_ECHO(tty) || L_ECHONL(tty)) { |
| echo_char_raw('\n', ldata); |
| process_echoes(tty); |
| } |
| goto handle_newline; |
| } |
| if (c == EOF_CHAR(tty)) { |
| if (ldata->read_cnt >= N_TTY_BUF_SIZE) |
| return; |
| if (ldata->canon_head != ldata->read_head) |
| set_bit(TTY_PUSH, &tty->flags); |
| c = __DISABLED_CHAR; |
| goto handle_newline; |
| } |
| if ((c == EOL_CHAR(tty)) || |
| (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { |
| parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) |
| ? 1 : 0; |
| if (ldata->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) { |
| if (L_ECHO(tty)) |
| process_output('\a', tty); |
| return; |
| } |
| /* |
| * XXX are EOL_CHAR and EOL2_CHAR echoed?!? |
| */ |
| if (L_ECHO(tty)) { |
| /* Record the column of first canon char. */ |
| if (ldata->canon_head == ldata->read_head) |
| echo_set_canon_col(ldata); |
| echo_char(c, tty); |
| process_echoes(tty); |
| } |
| /* |
| * XXX does PARMRK doubling happen for |
| * EOL_CHAR and EOL2_CHAR? |
| */ |
| if (parmrk) |
| put_tty_queue(c, ldata); |
| |
| handle_newline: |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| set_bit(ldata->read_head, ldata->read_flags); |
| put_tty_queue_nolock(c, ldata); |
| ldata->canon_head = ldata->read_head; |
| ldata->canon_data++; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
| if (waitqueue_active(&tty->read_wait)) |
| wake_up_interruptible(&tty->read_wait); |
| return; |
| } |
| } |
| |
| parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; |
| if (ldata->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) { |
| /* beep if no space */ |
| if (L_ECHO(tty)) |
| process_output('\a', tty); |
| return; |
| } |
| if (L_ECHO(tty)) { |
| finish_erasing(ldata); |
| if (c == '\n') |
| echo_char_raw('\n', ldata); |
| else { |
| /* Record the column of first canon char. */ |
| if (ldata->canon_head == ldata->read_head) |
| echo_set_canon_col(ldata); |
| echo_char(c, tty); |
| } |
| process_echoes(tty); |
| } |
| |
| if (parmrk) |
| put_tty_queue(c, ldata); |
| |
| put_tty_queue(c, ldata); |
| } |
| |
| |
| /** |
| * n_tty_write_wakeup - asynchronous I/O notifier |
| * @tty: tty device |
| * |
| * Required for the ptys, serial driver etc. since processes |
| * that attach themselves to the master and rely on ASYNC |
| * IO must be woken up |
| */ |
| |
| static void n_tty_write_wakeup(struct tty_struct *tty) |
| { |
| if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) |
| kill_fasync(&tty->fasync, SIGIO, POLL_OUT); |
| } |
| |
| /** |
| * n_tty_receive_buf - data receive |
| * @tty: terminal device |
| * @cp: buffer |
| * @fp: flag buffer |
| * @count: characters |
| * |
| * Called by the terminal driver when a block of characters has |
| * been received. This function must be called from soft contexts |
| * not from interrupt context. The driver is responsible for making |
| * calls one at a time and in order (or using flush_to_ldisc) |
| */ |
| |
| static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, |
| char *fp, int count) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| const unsigned char *p; |
| char *f, flags = TTY_NORMAL; |
| int i; |
| char buf[64]; |
| unsigned long cpuflags; |
| |
| if (ldata->real_raw) { |
| raw_spin_lock_irqsave(&ldata->read_lock, cpuflags); |
| i = min(N_TTY_BUF_SIZE - ldata->read_cnt, |
| N_TTY_BUF_SIZE - ldata->read_head); |
| i = min(count, i); |
| memcpy(ldata->read_buf + ldata->read_head, cp, i); |
| ldata->read_head = (ldata->read_head + i) & (N_TTY_BUF_SIZE-1); |
| ldata->read_cnt += i; |
| cp += i; |
| count -= i; |
| |
| i = min(N_TTY_BUF_SIZE - ldata->read_cnt, |
| N_TTY_BUF_SIZE - ldata->read_head); |
| i = min(count, i); |
| memcpy(ldata->read_buf + ldata->read_head, cp, i); |
| ldata->read_head = (ldata->read_head + i) & (N_TTY_BUF_SIZE-1); |
| ldata->read_cnt += i; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, cpuflags); |
| } else { |
| for (i = count, p = cp, f = fp; i; i--, p++) { |
| if (f) |
| flags = *f++; |
| switch (flags) { |
| case TTY_NORMAL: |
| n_tty_receive_char(tty, *p); |
| break; |
| case TTY_BREAK: |
| n_tty_receive_break(tty); |
| break; |
| case TTY_PARITY: |
| case TTY_FRAME: |
| n_tty_receive_parity_error(tty, *p); |
| break; |
| case TTY_OVERRUN: |
| n_tty_receive_overrun(tty); |
| break; |
| default: |
| printk(KERN_ERR "%s: unknown flag %d\n", |
| tty_name(tty, buf), flags); |
| break; |
| } |
| } |
| if (tty->ops->flush_chars) |
| tty->ops->flush_chars(tty); |
| } |
| |
| n_tty_set_room(tty); |
| |
| if ((!ldata->icanon && (ldata->read_cnt >= tty->minimum_to_wake)) || |
| L_EXTPROC(tty)) { |
| kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
| if (waitqueue_active(&tty->read_wait)) |
| wake_up_interruptible(&tty->read_wait); |
| } |
| |
| /* |
| * Check the remaining room for the input canonicalization |
| * mode. We don't want to throttle the driver if we're in |
| * canonical mode and don't have a newline yet! |
| */ |
| while (1) { |
| tty_set_flow_change(tty, TTY_THROTTLE_SAFE); |
| if (tty->receive_room >= TTY_THRESHOLD_THROTTLE) |
| break; |
| if (!tty_throttle_safe(tty)) |
| break; |
| } |
| __tty_set_flow_change(tty, 0); |
| } |
| |
| int is_ignored(int sig) |
| { |
| return (sigismember(¤t->blocked, sig) || |
| current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); |
| } |
| |
| /** |
| * n_tty_set_termios - termios data changed |
| * @tty: terminal |
| * @old: previous data |
| * |
| * Called by the tty layer when the user changes termios flags so |
| * that the line discipline can plan ahead. This function cannot sleep |
| * and is protected from re-entry by the tty layer. The user is |
| * guaranteed that this function will not be re-entered or in progress |
| * when the ldisc is closed. |
| * |
| * Locking: Caller holds tty->termios_mutex |
| */ |
| |
| static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int canon_change = 1; |
| |
| if (old) |
| canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON; |
| if (canon_change) { |
| bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); |
| ldata->canon_head = ldata->read_tail; |
| ldata->canon_data = 0; |
| ldata->erasing = 0; |
| } |
| |
| if (canon_change && !L_ICANON(tty) && ldata->read_cnt) |
| wake_up_interruptible(&tty->read_wait); |
| |
| ldata->icanon = (L_ICANON(tty) != 0); |
| if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { |
| ldata->raw = 1; |
| ldata->real_raw = 1; |
| n_tty_set_room(tty); |
| return; |
| } |
| if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || |
| I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || |
| I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || |
| I_PARMRK(tty)) { |
| bitmap_zero(ldata->process_char_map, 256); |
| |
| if (I_IGNCR(tty) || I_ICRNL(tty)) |
| set_bit('\r', ldata->process_char_map); |
| if (I_INLCR(tty)) |
| set_bit('\n', ldata->process_char_map); |
| |
| if (L_ICANON(tty)) { |
| set_bit(ERASE_CHAR(tty), ldata->process_char_map); |
| set_bit(KILL_CHAR(tty), ldata->process_char_map); |
| set_bit(EOF_CHAR(tty), ldata->process_char_map); |
| set_bit('\n', ldata->process_char_map); |
| set_bit(EOL_CHAR(tty), ldata->process_char_map); |
| if (L_IEXTEN(tty)) { |
| set_bit(WERASE_CHAR(tty), |
| ldata->process_char_map); |
| set_bit(LNEXT_CHAR(tty), |
| ldata->process_char_map); |
| set_bit(EOL2_CHAR(tty), |
| ldata->process_char_map); |
| if (L_ECHO(tty)) |
| set_bit(REPRINT_CHAR(tty), |
| ldata->process_char_map); |
| } |
| } |
| if (I_IXON(tty)) { |
| set_bit(START_CHAR(tty), ldata->process_char_map); |
| set_bit(STOP_CHAR(tty), ldata->process_char_map); |
| } |
| if (L_ISIG(tty)) { |
| set_bit(INTR_CHAR(tty), ldata->process_char_map); |
| set_bit(QUIT_CHAR(tty), ldata->process_char_map); |
| set_bit(SUSP_CHAR(tty), ldata->process_char_map); |
| } |
| clear_bit(__DISABLED_CHAR, ldata->process_char_map); |
| ldata->raw = 0; |
| ldata->real_raw = 0; |
| } else { |
| ldata->raw = 1; |
| if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && |
| (I_IGNPAR(tty) || !I_INPCK(tty)) && |
| (tty->driver->flags & TTY_DRIVER_REAL_RAW)) |
| ldata->real_raw = 1; |
| else |
| ldata->real_raw = 0; |
| } |
| n_tty_set_room(tty); |
| /* |
| * Fix tty hang when I_IXON(tty) is cleared, but the tty |
| * been stopped by STOP_CHAR(tty) before it. |
| */ |
| if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) { |
| start_tty(tty); |
| } |
| |
| /* The termios change make the tty ready for I/O */ |
| wake_up_interruptible(&tty->write_wait); |
| wake_up_interruptible(&tty->read_wait); |
| } |
| |
| /** |
| * n_tty_close - close the ldisc for this tty |
| * @tty: device |
| * |
| * Called from the terminal layer when this line discipline is |
| * being shut down, either because of a close or becsuse of a |
| * discipline change. The function will not be called while other |
| * ldisc methods are in progress. |
| */ |
| |
| static void n_tty_close(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| if (tty->link) |
| n_tty_packet_mode_flush(tty); |
| |
| kfree(ldata->read_buf); |
| kfree(ldata->echo_buf); |
| kfree(ldata); |
| tty->disc_data = NULL; |
| } |
| |
| /** |
| * n_tty_open - open an ldisc |
| * @tty: terminal to open |
| * |
| * Called when this line discipline is being attached to the |
| * terminal device. Can sleep. Called serialized so that no |
| * other events will occur in parallel. No further open will occur |
| * until a close. |
| */ |
| |
| static int n_tty_open(struct tty_struct *tty) |
| { |
| struct n_tty_data *ldata; |
| |
| ldata = kzalloc(sizeof(*ldata), GFP_KERNEL); |
| if (!ldata) |
| goto err; |
| |
| ldata->overrun_time = jiffies; |
| mutex_init(&ldata->atomic_read_lock); |
| mutex_init(&ldata->output_lock); |
| mutex_init(&ldata->echo_lock); |
| raw_spin_lock_init(&ldata->read_lock); |
| |
| /* These are ugly. Currently a malloc failure here can panic */ |
| ldata->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
| ldata->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); |
| if (!ldata->read_buf || !ldata->echo_buf) |
| goto err_free_bufs; |
| |
| tty->disc_data = ldata; |
| reset_buffer_flags(tty->disc_data); |
| ldata->column = 0; |
| tty->minimum_to_wake = 1; |
| tty->closing = 0; |
| /* indicate buffer work may resume */ |
| clear_bit(TTY_LDISC_HALTED, &tty->flags); |
| n_tty_set_termios(tty, NULL); |
| tty_unthrottle(tty); |
| |
| return 0; |
| err_free_bufs: |
| kfree(ldata->read_buf); |
| kfree(ldata->echo_buf); |
| kfree(ldata); |
| err: |
| return -ENOMEM; |
| } |
| |
| static inline int input_available_p(struct tty_struct *tty, int amt) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| tty_flush_to_ldisc(tty); |
| if (ldata->icanon && !L_EXTPROC(tty)) { |
| if (ldata->canon_data) |
| return 1; |
| } else if (ldata->read_cnt >= (amt ? amt : 1)) |
| return 1; |
| |
| return 0; |
| } |
| |
| /** |
| * copy_from_read_buf - copy read data directly |
| * @tty: terminal device |
| * @b: user data |
| * @nr: size of data |
| * |
| * Helper function to speed up n_tty_read. It is only called when |
| * ICANON is off; it copies characters straight from the tty queue to |
| * user space directly. It can be profitably called twice; once to |
| * drain the space from the tail pointer to the (physical) end of the |
| * buffer, and once to drain the space from the (physical) beginning of |
| * the buffer to head pointer. |
| * |
| * Called under the ldata->atomic_read_lock sem |
| * |
| */ |
| |
| static int copy_from_read_buf(struct tty_struct *tty, |
| unsigned char __user **b, |
| size_t *nr) |
| |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int retval; |
| size_t n; |
| unsigned long flags; |
| bool is_eof; |
| |
| retval = 0; |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| n = min(ldata->read_cnt, N_TTY_BUF_SIZE - ldata->read_tail); |
| n = min(*nr, n); |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| if (n) { |
| retval = copy_to_user(*b, &ldata->read_buf[ldata->read_tail], n); |
| n -= retval; |
| is_eof = n == 1 && |
| ldata->read_buf[ldata->read_tail] == EOF_CHAR(tty); |
| tty_audit_add_data(tty, &ldata->read_buf[ldata->read_tail], n, |
| ldata->icanon); |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| ldata->read_tail = (ldata->read_tail + n) & (N_TTY_BUF_SIZE-1); |
| ldata->read_cnt -= n; |
| /* Turn single EOF into zero-length read */ |
| if (L_EXTPROC(tty) && ldata->icanon && is_eof && !ldata->read_cnt) |
| n = 0; |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| *b += n; |
| *nr -= n; |
| } |
| return retval; |
| } |
| |
| extern ssize_t redirected_tty_write(struct file *, const char __user *, |
| size_t, loff_t *); |
| |
| /** |
| * job_control - check job control |
| * @tty: tty |
| * @file: file handle |
| * |
| * Perform job control management checks on this file/tty descriptor |
| * and if appropriate send any needed signals and return a negative |
| * error code if action should be taken. |
| * |
| * Locking: redirected write test is safe |
| * current->signal->tty check is safe |
| * ctrl_lock to safely reference tty->pgrp |
| */ |
| |
| static int job_control(struct tty_struct *tty, struct file *file) |
| { |
| /* Job control check -- must be done at start and after |
| every sleep (POSIX.1 7.1.1.4). */ |
| /* NOTE: not yet done after every sleep pending a thorough |
| check of the logic of this change. -- jlc */ |
| /* don't stop on /dev/console */ |
| if (file->f_op->write == redirected_tty_write || |
| current->signal->tty != tty) |
| return 0; |
| |
| spin_lock_irq(&tty->ctrl_lock); |
| if (!tty->pgrp) |
| printk(KERN_ERR "n_tty_read: no tty->pgrp!\n"); |
| else if (task_pgrp(current) != tty->pgrp) { |
| spin_unlock_irq(&tty->ctrl_lock); |
| if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) |
| return -EIO; |
| kill_pgrp(task_pgrp(current), SIGTTIN, 1); |
| set_thread_flag(TIF_SIGPENDING); |
| return -ERESTARTSYS; |
| } |
| spin_unlock_irq(&tty->ctrl_lock); |
| return 0; |
| } |
| |
| |
| /** |
| * n_tty_read - read function for tty |
| * @tty: tty device |
| * @file: file object |
| * @buf: userspace buffer pointer |
| * @nr: size of I/O |
| * |
| * Perform reads for the line discipline. We are guaranteed that the |
| * line discipline will not be closed under us but we may get multiple |
| * parallel readers and must handle this ourselves. We may also get |
| * a hangup. Always called in user context, may sleep. |
| * |
| * This code must be sure never to sleep through a hangup. |
| */ |
| |
| static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, |
| unsigned char __user *buf, size_t nr) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| unsigned char __user *b = buf; |
| DECLARE_WAITQUEUE(wait, current); |
| int c; |
| int minimum, time; |
| ssize_t retval = 0; |
| ssize_t size; |
| long timeout; |
| unsigned long flags; |
| int packet; |
| |
| do_it_again: |
| c = job_control(tty, file); |
| if (c < 0) |
| return c; |
| |
| minimum = time = 0; |
| timeout = MAX_SCHEDULE_TIMEOUT; |
| if (!ldata->icanon) { |
| time = (HZ / 10) * TIME_CHAR(tty); |
| minimum = MIN_CHAR(tty); |
| if (minimum) { |
| if (time) |
| tty->minimum_to_wake = 1; |
| else if (!waitqueue_active(&tty->read_wait) || |
| (tty->minimum_to_wake > minimum)) |
| tty->minimum_to_wake = minimum; |
| } else { |
| timeout = 0; |
| if (time) { |
| timeout = time; |
| time = 0; |
| } |
| tty->minimum_to_wake = minimum = 1; |
| } |
| } |
| |
| /* |
| * Internal serialization of reads. |
| */ |
| if (file->f_flags & O_NONBLOCK) { |
| if (!mutex_trylock(&ldata->atomic_read_lock)) |
| return -EAGAIN; |
| } else { |
| if (mutex_lock_interruptible(&ldata->atomic_read_lock)) |
| return -ERESTARTSYS; |
| } |
| packet = tty->packet; |
| |
| add_wait_queue(&tty->read_wait, &wait); |
| while (nr) { |
| /* First test for status change. */ |
| if (packet && tty->link->ctrl_status) { |
| unsigned char cs; |
| if (b != buf) |
| break; |
| spin_lock_irqsave(&tty->link->ctrl_lock, flags); |
| cs = tty->link->ctrl_status; |
| tty->link->ctrl_status = 0; |
| spin_unlock_irqrestore(&tty->link->ctrl_lock, flags); |
| if (tty_put_user(tty, cs, b++)) { |
| retval = -EFAULT; |
| b--; |
| break; |
| } |
| nr--; |
| break; |
| } |
| /* This statement must be first before checking for input |
| so that any interrupt will set the state back to |
| TASK_RUNNING. */ |
| set_current_state(TASK_INTERRUPTIBLE); |
| |
| if (((minimum - (b - buf)) < tty->minimum_to_wake) && |
| ((minimum - (b - buf)) >= 1)) |
| tty->minimum_to_wake = (minimum - (b - buf)); |
| |
| if (!input_available_p(tty, 0)) { |
| if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
| retval = -EIO; |
| break; |
| } |
| if (tty_hung_up_p(file)) |
| break; |
| if (!timeout) |
| break; |
| if (file->f_flags & O_NONBLOCK) { |
| retval = -EAGAIN; |
| break; |
| } |
| if (signal_pending(current)) { |
| retval = -ERESTARTSYS; |
| break; |
| } |
| /* FIXME: does n_tty_set_room need locking ? */ |
| n_tty_set_room(tty); |
| timeout = schedule_timeout(timeout); |
| continue; |
| } |
| __set_current_state(TASK_RUNNING); |
| |
| /* Deal with packet mode. */ |
| if (packet && b == buf) { |
| if (tty_put_user(tty, TIOCPKT_DATA, b++)) { |
| retval = -EFAULT; |
| b--; |
| break; |
| } |
| nr--; |
| } |
| |
| if (ldata->icanon && !L_EXTPROC(tty)) { |
| /* N.B. avoid overrun if nr == 0 */ |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| while (nr && ldata->read_cnt) { |
| int eol; |
| |
| eol = test_and_clear_bit(ldata->read_tail, |
| ldata->read_flags); |
| c = ldata->read_buf[ldata->read_tail]; |
| ldata->read_tail = ((ldata->read_tail+1) & |
| (N_TTY_BUF_SIZE-1)); |
| ldata->read_cnt--; |
| if (eol) { |
| /* this test should be redundant: |
| * we shouldn't be reading data if |
| * canon_data is 0 |
| */ |
| if (--ldata->canon_data < 0) |
| ldata->canon_data = 0; |
| } |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| |
| if (!eol || (c != __DISABLED_CHAR)) { |
| if (tty_put_user(tty, c, b++)) { |
| retval = -EFAULT; |
| b--; |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| break; |
| } |
| nr--; |
| } |
| if (eol) { |
| tty_audit_push(tty); |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| break; |
| } |
| raw_spin_lock_irqsave(&ldata->read_lock, flags); |
| } |
| raw_spin_unlock_irqrestore(&ldata->read_lock, flags); |
| if (retval) |
| break; |
| } else { |
| int uncopied; |
| /* The copy function takes the read lock and handles |
| locking internally for this case */ |
| uncopied = copy_from_read_buf(tty, &b, &nr); |
| uncopied += copy_from_read_buf(tty, &b, &nr); |
| if (uncopied) { |
| retval = -EFAULT; |
| break; |
| } |
| } |
| |
| /* If there is enough space in the read buffer now, let the |
| * low-level driver know. We use n_tty_chars_in_buffer() to |
| * check the buffer, as it now knows about canonical mode. |
| * Otherwise, if the driver is throttled and the line is |
| * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, |
| * we won't get any more characters. |
| */ |
| while (1) { |
| tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE); |
| if (n_tty_chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) |
| break; |
| if (!tty->count) |
| break; |
| n_tty_set_room(tty); |
| if (!tty_unthrottle_safe(tty)) |
| break; |
| } |
| __tty_set_flow_change(tty, 0); |
| |
| if (b - buf >= minimum) |
| break; |
| if (time) |
| timeout = time; |
| } |
| mutex_unlock(&ldata->atomic_read_lock); |
| remove_wait_queue(&tty->read_wait, &wait); |
| |
| if (!waitqueue_active(&tty->read_wait)) |
| tty->minimum_to_wake = minimum; |
| |
| __set_current_state(TASK_RUNNING); |
| size = b - buf; |
| if (size) { |
| retval = size; |
| if (nr) |
| clear_bit(TTY_PUSH, &tty->flags); |
| } else if (test_and_clear_bit(TTY_PUSH, &tty->flags)) |
| goto do_it_again; |
| |
| n_tty_set_room(tty); |
| return retval; |
| } |
| |
| /** |
| * n_tty_write - write function for tty |
| * @tty: tty device |
| * @file: file object |
| * @buf: userspace buffer pointer |
| * @nr: size of I/O |
| * |
| * Write function of the terminal device. This is serialized with |
| * respect to other write callers but not to termios changes, reads |
| * and other such events. Since the receive code will echo characters, |
| * thus calling driver write methods, the output_lock is used in |
| * the output processing functions called here as well as in the |
| * echo processing function to protect the column state and space |
| * left in the buffer. |
| * |
| * This code must be sure never to sleep through a hangup. |
| * |
| * Locking: output_lock to protect column state and space left |
| * (note that the process_output*() functions take this |
| * lock themselves) |
| */ |
| |
| static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, |
| const unsigned char *buf, size_t nr) |
| { |
| const unsigned char *b = buf; |
| DECLARE_WAITQUEUE(wait, current); |
| int c; |
| ssize_t retval = 0; |
| |
| /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ |
| if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { |
| retval = tty_check_change(tty); |
| if (retval) |
| return retval; |
| } |
| |
| /* Write out any echoed characters that are still pending */ |
| process_echoes(tty); |
| |
| add_wait_queue(&tty->write_wait, &wait); |
| while (1) { |
| set_current_state(TASK_INTERRUPTIBLE); |
| if (signal_pending(current)) { |
| retval = -ERESTARTSYS; |
| break; |
| } |
| if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { |
| retval = -EIO; |
| break; |
| } |
| if (O_OPOST(tty) && !(test_bit(TTY_HW_COOK_OUT, &tty->flags))) { |
| while (nr > 0) { |
| ssize_t num = process_output_block(tty, b, nr); |
| if (num < 0) { |
| if (num == -EAGAIN) |
| break; |
| retval = num; |
| goto break_out; |
| } |
| b += num; |
| nr -= num; |
| if (nr == 0) |
| break; |
| c = *b; |
| if (process_output(c, tty) < 0) |
| break; |
| b++; nr--; |
| } |
| if (tty->ops->flush_chars) |
| tty->ops->flush_chars(tty); |
| } else { |
| struct n_tty_data *ldata = tty->disc_data; |
| |
| while (nr > 0) { |
| mutex_lock(&ldata->output_lock); |
| c = tty->ops->write(tty, b, nr); |
| mutex_unlock(&ldata->output_lock); |
| if (c < 0) { |
| retval = c; |
| goto break_out; |
| } |
| if (!c) |
| break; |
| b += c; |
| nr -= c; |
| } |
| } |
| if (!nr) |
| break; |
| if (file->f_flags & O_NONBLOCK) { |
| retval = -EAGAIN; |
| break; |
| } |
| schedule(); |
| } |
| break_out: |
| __set_current_state(TASK_RUNNING); |
| remove_wait_queue(&tty->write_wait, &wait); |
| if (b - buf != nr && tty->fasync) |
| set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
| return (b - buf) ? b - buf : retval; |
| } |
| |
| /** |
| * n_tty_poll - poll method for N_TTY |
| * @tty: terminal device |
| * @file: file accessing it |
| * @wait: poll table |
| * |
| * Called when the line discipline is asked to poll() for data or |
| * for special events. This code is not serialized with respect to |
| * other events save open/close. |
| * |
| * This code must be sure never to sleep through a hangup. |
| * Called without the kernel lock held - fine |
| */ |
| |
| static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, |
| poll_table *wait) |
| { |
| unsigned int mask = 0; |
| |
| poll_wait(file, &tty->read_wait, wait); |
| poll_wait(file, &tty->write_wait, wait); |
| if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) |
| mask |= POLLIN | POLLRDNORM; |
| if (tty->packet && tty->link->ctrl_status) |
| mask |= POLLPRI | POLLIN | POLLRDNORM; |
| if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
| mask |= POLLHUP; |
| if (tty_hung_up_p(file)) |
| mask |= POLLHUP; |
| if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { |
| if (MIN_CHAR(tty) && !TIME_CHAR(tty)) |
| tty->minimum_to_wake = MIN_CHAR(tty); |
| else |
| tty->minimum_to_wake = 1; |
| } |
| if (tty->ops->write && !tty_is_writelocked(tty) && |
| tty_chars_in_buffer(tty) < WAKEUP_CHARS && |
| tty_write_room(tty) > 0) |
| mask |= POLLOUT | POLLWRNORM; |
| return mask; |
| } |
| |
| static unsigned long inq_canon(struct n_tty_data *ldata) |
| { |
| int nr, head, tail; |
| |
| if (!ldata->canon_data) |
| return 0; |
| head = ldata->canon_head; |
| tail = ldata->read_tail; |
| nr = (head - tail) & (N_TTY_BUF_SIZE-1); |
| /* Skip EOF-chars.. */ |
| while (head != tail) { |
| if (test_bit(tail, ldata->read_flags) && |
| ldata->read_buf[tail] == __DISABLED_CHAR) |
| nr--; |
| tail = (tail+1) & (N_TTY_BUF_SIZE-1); |
| } |
| return nr; |
| } |
| |
| static int n_tty_ioctl(struct tty_struct *tty, struct file *file, |
| unsigned int cmd, unsigned long arg) |
| { |
| struct n_tty_data *ldata = tty->disc_data; |
| int retval; |
| |
| switch (cmd) { |
| case TIOCOUTQ: |
| return put_user(tty_chars_in_buffer(tty), (int __user *) arg); |
| case TIOCINQ: |
| /* FIXME: Locking */ |
| retval = ldata->read_cnt; |
| if (L_ICANON(tty)) |
| retval = inq_canon(ldata); |
| return put_user(retval, (unsigned int __user *) arg); |
| default: |
| return n_tty_ioctl_helper(tty, file, cmd, arg); |
| } |
| } |
| |
| struct tty_ldisc_ops tty_ldisc_N_TTY = { |
| .magic = TTY_LDISC_MAGIC, |
| .name = "n_tty", |
| .open = n_tty_open, |
| .close = n_tty_close, |
| .flush_buffer = n_tty_flush_buffer, |
| .chars_in_buffer = n_tty_chars_in_buffer, |
| .read = n_tty_read, |
| .write = n_tty_write, |
| .ioctl = n_tty_ioctl, |
| .set_termios = n_tty_set_termios, |
| .poll = n_tty_poll, |
| .receive_buf = n_tty_receive_buf, |
| .write_wakeup = n_tty_write_wakeup |
| }; |
| |
| /** |
| * n_tty_inherit_ops - inherit N_TTY methods |
| * @ops: struct tty_ldisc_ops where to save N_TTY methods |
| * |
| * Enables a 'subclass' line discipline to 'inherit' N_TTY |
| * methods. |
| */ |
| |
| void n_tty_inherit_ops(struct tty_ldisc_ops *ops) |
| { |
| *ops = tty_ldisc_N_TTY; |
| ops->owner = NULL; |
| ops->refcount = ops->flags = 0; |
| } |
| EXPORT_SYMBOL_GPL(n_tty_inherit_ops); |