/* * 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 Public * License. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define CONSOLE_DEV MKDEV(TTY_MAJOR,0) #ifndef MIN #define MIN(a,b) ((a) < (b) ? (a) : (b)) #endif /* 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 (N_TTY_BUF_SIZE - 128) #define TTY_THRESHOLD_UNTHROTTLE 128 static inline void put_tty_queue(unsigned char c, struct tty_struct *tty) { if (tty->read_cnt < N_TTY_BUF_SIZE) { tty->read_buf[tty->read_head] = c; tty->read_head = (tty->read_head + 1) & (N_TTY_BUF_SIZE-1); tty->read_cnt++; } } /* * Flush the input buffer */ void n_tty_flush_buffer(struct tty_struct * tty) { tty->read_head = tty->read_tail = tty->read_cnt = 0; tty->canon_head = tty->canon_data = tty->erasing = 0; memset(&tty->read_flags, 0, sizeof tty->read_flags); if (!tty->link) return; if (tty->driver.unthrottle) (tty->driver.unthrottle)(tty); if (tty->link->packet) { tty->ctrl_status |= TIOCPKT_FLUSHREAD; wake_up_interruptible(&tty->link->read_wait); } } /* * Return number of characters buffered to be delivered to user */ int n_tty_chars_in_buffer(struct tty_struct *tty) { return tty->read_cnt; } /* * Perform OPOST processing. Returns -1 when the output device is * full and the character must be retried. */ static int opost(unsigned char c, struct tty_struct *tty) { int space, spaces; space = tty->driver.write_room(tty); if (!space) return -1; if (O_OPOST(tty)) { switch (c) { case '\n': if (O_ONLRET(tty)) tty->column = 0; if (O_ONLCR(tty)) { if (space < 2) return -1; tty->driver.put_char(tty, '\r'); tty->column = 0; } tty->canon_column = tty->column; break; case '\r': if (O_ONOCR(tty) && tty->column == 0) return 0; if (O_OCRNL(tty)) { c = '\n'; if (O_ONLRET(tty)) tty->canon_column = tty->column = 0; break; } tty->canon_column = tty->column = 0; break; case '\t': spaces = 8 - (tty->column & 7); if (O_TABDLY(tty) == XTABS) { if (space < spaces) return -1; tty->column += spaces; tty->driver.write(tty, 0, " ", spaces); return 0; } tty->column += spaces; break; case '\b': if (tty->column > 0) tty->column--; break; default: if (O_OLCUC(tty)) c = toupper(c); if (!iscntrl(c)) tty->column++; break; } } tty->driver.put_char(tty, c); return 0; } static inline void put_char(unsigned char c, struct tty_struct *tty) { tty->driver.put_char(tty, c); } /* Must be called only when L_ECHO(tty) is true. */ static void echo_char(unsigned char c, struct tty_struct *tty) { if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') { put_char('^', tty); put_char(c ^ 0100, tty); tty->column += 2; } else opost(c, tty); } static inline void finish_erasing(struct tty_struct *tty) { if (tty->erasing) { put_char('/', tty); tty->column += 2; tty->erasing = 0; } } static void eraser(unsigned char c, struct tty_struct *tty) { enum { ERASE, WERASE, KILL } kill_type; int head, seen_alnums; if (tty->read_head == tty->canon_head) { /* opost('\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)) { tty->read_cnt -= ((tty->read_head - tty->canon_head) & (N_TTY_BUF_SIZE - 1)); tty->read_head = tty->canon_head; return; } if (!L_ECHOK(tty) || !L_ECHOKE(tty)) { tty->read_cnt -= ((tty->read_head - tty->canon_head) & (N_TTY_BUF_SIZE - 1)); tty->read_head = tty->canon_head; finish_erasing(tty); echo_char(KILL_CHAR(tty), tty); /* Add a newline if ECHOK is on and ECHOKE is off. */ if (L_ECHOK(tty)) opost('\n', tty); return; } kill_type = KILL; } seen_alnums = 0; while (tty->read_head != tty->canon_head) { head = (tty->read_head - 1) & (N_TTY_BUF_SIZE-1); c = tty->read_buf[head]; if (kill_type == WERASE) { /* Equivalent to BSD's ALTWERASE. */ if (isalnum(c) || c == '_') seen_alnums++; else if (seen_alnums) break; } tty->read_head = head; tty->read_cnt--; if (L_ECHO(tty)) { if (L_ECHOPRT(tty)) { if (!tty->erasing) { put_char('\\', tty); tty->column++; tty->erasing = 1; } echo_char(c, tty); } else if (!L_ECHOE(tty)) { echo_char(ERASE_CHAR(tty), tty); } else if (c == '\t') { unsigned int col = tty->canon_column; unsigned long tail = tty->canon_head; /* Find the column of the last char. */ while (tail != tty->read_head) { c = tty->read_buf[tail]; if (c == '\t') col = (col | 7) + 1; else if (iscntrl(c)) { if (L_ECHOCTL(tty)) col += 2; } else col++; tail = (tail+1) & (N_TTY_BUF_SIZE-1); } /* Now backup to that column. */ while (tty->column > col) { /* Can't use opost here. */ put_char('\b', tty); tty->column--; } } else { if (iscntrl(c) && L_ECHOCTL(tty)) { put_char('\b', tty); put_char(' ', tty); put_char('\b', tty); tty->column--; } if (!iscntrl(c) || L_ECHOCTL(tty)) { put_char('\b', tty); put_char(' ', tty); put_char('\b', tty); tty->column--; } } } if (kill_type == ERASE) break; } if (tty->read_head == tty->canon_head) finish_erasing(tty); } static void isig(int sig, struct tty_struct *tty) { if (tty->pgrp > 0) kill_pg(tty->pgrp, sig, 1); if (!L_NOFLSH(tty)) { n_tty_flush_buffer(tty); if (tty->driver.flush_buffer) tty->driver.flush_buffer(tty); } } static inline void n_tty_receive_break(struct tty_struct *tty) { if (I_IGNBRK(tty)) return; if (I_BRKINT(tty)) { isig(SIGINT, tty); return; } if (I_PARMRK(tty)) { put_tty_queue('\377', tty); put_tty_queue('\0', tty); } put_tty_queue('\0', tty); wake_up_interruptible(&tty->read_wait); } static inline void n_tty_receive_overrun(struct tty_struct *tty) { char buf[64]; tty->num_overrun++; if (tty->overrun_time < (jiffies - HZ)) { printk("%s: %d input overrun(s)\n", _tty_name(tty, buf), tty->num_overrun); tty->overrun_time = jiffies; tty->num_overrun = 0; } } static inline void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c) { if (I_IGNPAR(tty)) { return; } if (I_PARMRK(tty)) { put_tty_queue('\377', tty); put_tty_queue('\0', tty); put_tty_queue(c, tty); } else put_tty_queue('\0', tty); wake_up_interruptible(&tty->read_wait); } static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) { if (tty->raw) { put_tty_queue(c, tty); return; } if (tty->stopped && I_IXON(tty) && I_IXANY(tty)) { start_tty(tty); return; } if (I_ISTRIP(tty)) c &= 0x7f; if (I_IUCLC(tty) && L_IEXTEN(tty)) c=tolower(c); if (tty->closing) { if (I_IXON(tty)) { if (c == START_CHAR(tty)) start_tty(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, &tty->process_char_map) || tty->lnext) { finish_erasing(tty); tty->lnext = 0; if (L_ECHO(tty)) { if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { put_char('\a', tty); /* beep if no space */ return; } /* Record the column of first canon char. */ if (tty->canon_head == tty->read_head) tty->canon_column = tty->column; echo_char(c, tty); } if (I_PARMRK(tty) && c == (unsigned char) '\377') put_tty_queue(c, tty); put_tty_queue(c, 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 (I_IXON(tty)) { if (c == START_CHAR(tty)) { start_tty(tty); return; } if (c == STOP_CHAR(tty)) { stop_tty(tty); return; } } if (L_ISIG(tty)) { if (c == INTR_CHAR(tty)) { isig(SIGINT, tty); return; } if (c == QUIT_CHAR(tty)) { isig(SIGQUIT, tty); return; } if (c == SUSP_CHAR(tty)) { if (!is_orphaned_pgrp(tty->pgrp)) isig(SIGTSTP, tty); return; } } if (L_ICANON(tty)) { if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { eraser(c, tty); return; } if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { tty->lnext = 1; if (L_ECHO(tty)) { finish_erasing(tty); if (L_ECHOCTL(tty)) { put_char('^', tty); put_char('\b', tty); } } return; } if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) { unsigned long tail = tty->canon_head; finish_erasing(tty); echo_char(c, tty); opost('\n', tty); while (tail != tty->read_head) { echo_char(tty->read_buf[tail], tty); tail = (tail+1) & (N_TTY_BUF_SIZE-1); } return; } if (c == '\n') { if (L_ECHO(tty) || L_ECHONL(tty)) { if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { put_char('\a', tty); return; } opost('\n', tty); } goto handle_newline; } if (c == EOF_CHAR(tty)) { if (tty->canon_head != tty->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))) { /* * XXX are EOL_CHAR and EOL2_CHAR echoed?!? */ if (L_ECHO(tty)) { if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { put_char('\a', tty); return; } /* Record the column of first canon char. */ if (tty->canon_head == tty->read_head) tty->canon_column = tty->column; echo_char(c, tty); } /* * XXX does PARMRK doubling happen for * EOL_CHAR and EOL2_CHAR? */ if (I_PARMRK(tty) && c == (unsigned char) '\377') put_tty_queue(c, tty); handle_newline: set_bit(tty->read_head, &tty->read_flags); put_tty_queue(c, tty); tty->canon_head = tty->read_head; tty->canon_data++; if (tty->fasync) kill_fasync(tty->fasync, SIGIO); if (tty->read_wait) wake_up_interruptible(&tty->read_wait); return; } } finish_erasing(tty); if (L_ECHO(tty)) { if (tty->read_cnt >= N_TTY_BUF_SIZE-1) { put_char('\a', tty); /* beep if no space */ return; } if (c == '\n') opost('\n', tty); else { /* Record the column of first canon char. */ if (tty->canon_head == tty->read_head) tty->canon_column = tty->column; echo_char(c, tty); } } if (I_PARMRK(tty) && c == (unsigned char) '\377') put_tty_queue(c, tty); put_tty_queue(c, tty); } static void n_tty_receive_buf(struct tty_struct *tty, unsigned char *cp, char *fp, int count) { unsigned char *p; char *f, flags = 0; int i; if (!tty->read_buf) return; if (tty->real_raw) { i = MIN(count, MIN(N_TTY_BUF_SIZE - tty->read_cnt, N_TTY_BUF_SIZE - tty->read_head)); memcpy(tty->read_buf + tty->read_head, cp, i); tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); tty->read_cnt += i; cp += i; count -= i; i = MIN(count, MIN(N_TTY_BUF_SIZE - tty->read_cnt, N_TTY_BUF_SIZE - tty->read_head)); memcpy(tty->read_buf + tty->read_head, cp, i); tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1); tty->read_cnt += i; } 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("%s: unknown flag %d\n", tty_name(tty), flags); break; } } if (tty->driver.flush_chars) tty->driver.flush_chars(tty); } if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) { if (tty->fasync) kill_fasync(tty->fasync, SIGIO); if (tty->read_wait) wake_up_interruptible(&tty->read_wait); } if ((tty->read_cnt >= TTY_THRESHOLD_THROTTLE) && tty->driver.throttle && !set_bit(TTY_THROTTLED, &tty->flags)) tty->driver.throttle(tty); } static int n_tty_receive_room(struct tty_struct *tty) { int left = N_TTY_BUF_SIZE - tty->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 (tty->icanon && !tty->canon_data) return N_TTY_BUF_SIZE; if (left > 0) return left; return 0; } int is_ignored(int sig) { return ((current->blocked & (1<<(sig-1))) || (current->sigaction[sig-1].sa_handler == SIG_IGN)); } static void n_tty_set_termios(struct tty_struct *tty, struct termios * old) { if (!tty) return; tty->icanon = (L_ICANON(tty) != 0); 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)) { cli(); memset(tty->process_char_map, 0, 256/32); if (I_IGNCR(tty) || I_ICRNL(tty)) set_bit('\r', &tty->process_char_map); if (I_INLCR(tty)) set_bit('\n', &tty->process_char_map); if (L_ICANON(tty)) { set_bit(ERASE_CHAR(tty), &tty->process_char_map); set_bit(KILL_CHAR(tty), &tty->process_char_map); set_bit(EOF_CHAR(tty), &tty->process_char_map); set_bit('\n', &tty->process_char_map); set_bit(EOL_CHAR(tty), &tty->process_char_map); if (L_IEXTEN(tty)) { set_bit(WERASE_CHAR(tty), &tty->process_char_map); set_bit(LNEXT_CHAR(tty), &tty->process_char_map); set_bit(EOL2_CHAR(tty), &tty->process_char_map); if (L_ECHO(tty)) set_bit(REPRINT_CHAR(tty), &tty->process_char_map); } } if (I_IXON(tty)) { set_bit(START_CHAR(tty), &tty->process_char_map); set_bit(STOP_CHAR(tty), &tty->process_char_map); } if (L_ISIG(tty)) { set_bit(INTR_CHAR(tty), &tty->process_char_map); set_bit(QUIT_CHAR(tty), &tty->process_char_map); set_bit(SUSP_CHAR(tty), &tty->process_char_map); } clear_bit(__DISABLED_CHAR, &tty->process_char_map); sti(); tty->raw = 0; tty->real_raw = 0; } else { tty->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)) tty->real_raw = 1; else tty->real_raw = 0; } } static void n_tty_close(struct tty_struct *tty) { n_tty_flush_buffer(tty); if (tty->read_buf) { free_page((unsigned long) tty->read_buf); tty->read_buf = 0; } } static int n_tty_open(struct tty_struct *tty) { if (!tty) return -EINVAL; if (!tty->read_buf) { tty->read_buf = (unsigned char *) get_free_page(intr_count ? GFP_ATOMIC : GFP_KERNEL); if (!tty->read_buf) return -ENOMEM; } memset(tty->read_buf, 0, N_TTY_BUF_SIZE); tty->read_head = tty->read_tail = tty->read_cnt = 0; memset(tty->read_flags, 0, sizeof(tty->read_flags)); n_tty_set_termios(tty, 0); tty->minimum_to_wake = 1; tty->closing = 0; return 0; } static inline int input_available_p(struct tty_struct *tty, int amt) { if (L_ICANON(tty)) { if (tty->canon_data) return 1; } else if (tty->read_cnt >= (amt ? amt : 1)) return 1; return 0; } /* * Helper function to speed up read_chan. 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. */ static inline void copy_from_read_buf(struct tty_struct *tty, unsigned char **b, unsigned int *nr) { int n; n = MIN(*nr, MIN(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail)); if (!n) return; memcpy_tofs(*b, &tty->read_buf[tty->read_tail], n); tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1); tty->read_cnt -= n; *b += n; *nr -= n; } static int read_chan(struct tty_struct *tty, struct file *file, unsigned char *buf, unsigned int nr) { struct wait_queue wait = { current, NULL }; int c; unsigned char *b = buf; int minimum, time; int retval = 0; int size; do_it_again: if (!tty->read_buf) { printk("n_tty_read_chan: called with read_buf == NULL?!?\n"); return -EIO; } /* 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_inode->i_rdev != CONSOLE_DEV && current->tty == tty) { if (tty->pgrp <= 0) printk("read_chan: tty->pgrp <= 0!\n"); else if (current->pgrp != tty->pgrp) { if (is_ignored(SIGTTIN) || is_orphaned_pgrp(current->pgrp)) return -EIO; kill_pg(current->pgrp, SIGTTIN, 1); return -ERESTARTSYS; } } if (L_ICANON(tty)) { minimum = time = 0; current->timeout = (unsigned long) -1; } else { time = (HZ / 10) * TIME_CHAR(tty); minimum = MIN_CHAR(tty); if (minimum) { current->timeout = (unsigned long) -1; if (time) tty->minimum_to_wake = 1; else if (!tty->read_wait || (tty->minimum_to_wake > minimum)) tty->minimum_to_wake = minimum; } else { if (time) { current->timeout = time + jiffies; time = 0; } else current->timeout = 0; tty->minimum_to_wake = minimum = 1; } } add_wait_queue(&tty->read_wait, &wait); while (1) { /* First test for status change. */ if (tty->packet && tty->link->ctrl_status) { if (b != buf) break; put_fs_byte(tty->link->ctrl_status, b++); tty->link->ctrl_status = 0; break; } /* This statement must be first before checking for input so that any interrupt will set the state back to TASK_RUNNING. */ 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 (tty->flags & (1 << TTY_SLAVE_CLOSED)) { retval = -EIO; break; } if (tty_hung_up_p(file)) break; if (!current->timeout) break; if (file->f_flags & O_NONBLOCK) { retval = -EAGAIN; break; } if (current->signal & ~current->blocked) { retval = -ERESTARTSYS; break; } schedule(); continue; } current->state = TASK_RUNNING; /* Deal with packet mode. */ if (tty->packet && b == buf) { put_fs_byte(TIOCPKT_DATA, b++); nr--; } if (L_ICANON(tty)) { while (1) { int eol; disable_bh(TQUEUE_BH); if (!tty->read_cnt) { enable_bh(TQUEUE_BH); break; } eol = clear_bit(tty->read_tail, &tty->read_flags); c = tty->read_buf[tty->read_tail]; tty->read_tail = ((tty->read_tail+1) & (N_TTY_BUF_SIZE-1)); tty->read_cnt--; enable_bh(TQUEUE_BH); if (!eol) { put_fs_byte(c, b++); if (--nr) continue; break; } if (--tty->canon_data < 0) { tty->canon_data = 0; } if (c != __DISABLED_CHAR) { put_fs_byte(c, b++); nr--; } break; } } else { disable_bh(TQUEUE_BH); copy_from_read_buf(tty, &b, &nr); copy_from_read_buf(tty, &b, &nr); enable_bh(TQUEUE_BH); } /* If there is enough space in the read buffer now, let the low-level driver know. */ if (tty->driver.unthrottle && (tty->read_cnt <= TTY_THRESHOLD_UNTHROTTLE) && clear_bit(TTY_THROTTLED, &tty->flags)) tty->driver.unthrottle(tty); if (b - buf >= minimum || !nr) break; if (time) current->timeout = time + jiffies; } remove_wait_queue(&tty->read_wait, &wait); if (!tty->read_wait) tty->minimum_to_wake = minimum; current->state = TASK_RUNNING; current->timeout = 0; size = b - buf; if (size && nr) clear_bit(TTY_PUSH, &tty->flags); if (!size && clear_bit(TTY_PUSH, &tty->flags)) goto do_it_again; if (!size && !retval) clear_bit(TTY_PUSH, &tty->flags); return (size ? size : retval); } static int write_chan(struct tty_struct * tty, struct file * file, unsigned char * buf, unsigned int nr) { struct wait_queue wait = { current, NULL }; int c; unsigned char *b = buf; int retval = 0; /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ if (L_TOSTOP(tty) && file->f_inode->i_rdev != CONSOLE_DEV) { retval = tty_check_change(tty); if (retval) return retval; } add_wait_queue(&tty->write_wait, &wait); while (1) { current->state = TASK_INTERRUPTIBLE; if (current->signal & ~current->blocked) { retval = -ERESTARTSYS; break; } if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { retval = -EIO; break; } if (O_OPOST(tty)) { while (nr > 0) { c = get_fs_byte(b); if (opost(c, tty) < 0) break; b++; nr--; } if (tty->driver.flush_chars) tty->driver.flush_chars(tty); } else { c = tty->driver.write(tty, 1, b, nr); b += c; nr -= c; } if (!nr) break; if (file->f_flags & O_NONBLOCK) { retval = -EAGAIN; break; } schedule(); } current->state = TASK_RUNNING; remove_wait_queue(&tty->write_wait, &wait); return (b - buf) ? b - buf : retval; } static int normal_select(struct tty_struct * tty, struct inode * inode, struct file * file, int sel_type, select_table *wait) { switch (sel_type) { case SEL_IN: if (input_available_p(tty, TIME_CHAR(tty) ? 0 : MIN_CHAR(tty))) return 1; /* fall through */ case SEL_EX: if (tty->packet && tty->link->ctrl_status) return 1; if (tty->flags & (1 << TTY_SLAVE_CLOSED)) return 1; if (tty_hung_up_p(file)) return 1; if (!tty->read_wait) { if (MIN_CHAR(tty) && !TIME_CHAR(tty)) tty->minimum_to_wake = MIN_CHAR(tty); else tty->minimum_to_wake = 1; } select_wait(&tty->read_wait, wait); return 0; case SEL_OUT: if (tty->driver.chars_in_buffer(tty) < WAKEUP_CHARS) return 1; select_wait(&tty->write_wait, wait); return 0; } return 0; } struct tty_ldisc tty_ldisc_N_TTY = { TTY_LDISC_MAGIC, /* magic */ 0, /* num */ 0, /* flags */ n_tty_open, /* open */ n_tty_close, /* close */ n_tty_flush_buffer, /* flush_buffer */ n_tty_chars_in_buffer, /* chars_in_buffer */ read_chan, /* read */ write_chan, /* write */ n_tty_ioctl, /* ioctl */ n_tty_set_termios, /* set_termios */ normal_select, /* select */ n_tty_receive_buf, /* receive_buf */ n_tty_receive_room, /* receive_room */ 0 /* write_wakeup */ };