/* * 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 * 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 . * Also fixed a bug in BLOCKING mode where write_chan returns * EAGAIN */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* 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 static inline unsigned char *alloc_buf(void) { gfp_t prio = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL; if (PAGE_SIZE != N_TTY_BUF_SIZE) return kmalloc(N_TTY_BUF_SIZE, prio); else return (unsigned char *)__get_free_page(prio); } static inline void free_buf(unsigned char *buf) { if (PAGE_SIZE != N_TTY_BUF_SIZE) kfree(buf); else free_page((unsigned long) buf); } static inline int tty_put_user(struct tty_struct *tty, unsigned char x, unsigned char __user *ptr) { tty_audit_add_data(tty, &x, 1); 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) { 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 (left <= 0) left = tty->icanon && !tty->canon_data; tty->receive_room = left; } static void put_tty_queue_nolock(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++; } } static void put_tty_queue(unsigned char c, struct tty_struct *tty) { unsigned long flags; /* * The problem of stomping on the buffers ends here. * Why didn't anyone see this one coming? --AJK */ spin_lock_irqsave(&tty->read_lock, flags); put_tty_queue_nolock(c, tty); spin_unlock_irqrestore(&tty->read_lock, flags); } /** * check_unthrottle - allow new receive data * @tty; tty device * * Check whether to call the driver.unthrottle function. * We test the TTY_THROTTLED bit first so that it always * indicates the current state. The decision about whether * it is worth allowing more input has been taken by the caller. * Can sleep, may be called under the atomic_read_lock mutex but * this is not guaranteed. */ static void check_unthrottle(struct tty_struct * tty) { if (tty->count && test_and_clear_bit(TTY_THROTTLED, &tty->flags) && tty->driver->unthrottle) tty->driver->unthrottle(tty); } /** * reset_buffer_flags - reset buffer state * @tty: terminal to reset * * Reset the read buffer counters, clear the flags, * and make sure the driver is unthrottled. Called * from n_tty_open() and n_tty_flush_buffer(). */ static void reset_buffer_flags(struct tty_struct *tty) { unsigned long flags; spin_lock_irqsave(&tty->read_lock, flags); tty->read_head = tty->read_tail = tty->read_cnt = 0; spin_unlock_irqrestore(&tty->read_lock, flags); tty->canon_head = tty->canon_data = tty->erasing = 0; memset(&tty->read_flags, 0, sizeof tty->read_flags); n_tty_set_room(tty); check_unthrottle(tty); } /** * n_tty_flush_buffer - clean input queue * @tty: terminal device * * Flush the input buffer. Called when the line discipline is * being closed, 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). * * FIXME: tty->ctrl_status is not spinlocked and relies on * lock_kernel() still. */ static void n_tty_flush_buffer(struct tty_struct * tty) { /* clear everything and unthrottle the driver */ reset_buffer_flags(tty); if (!tty->link) return; if (tty->link->packet) { tty->ctrl_status |= TIOCPKT_FLUSHREAD; wake_up_interruptible(&tty->link->read_wait); } } /** * 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. */ static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) { unsigned long flags; ssize_t n = 0; spin_lock_irqsave(&tty->read_lock, flags); if (!tty->icanon) { n = tty->read_cnt; } else if (tty->canon_data) { n = (tty->canon_head > tty->read_tail) ? tty->canon_head - tty->read_tail : tty->canon_head + (N_TTY_BUF_SIZE - tty->read_tail); } spin_unlock_irqrestore(&tty->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); } /** * opost - output post processor * @c: character (or partial unicode symbol) * @tty: terminal device * * Perform OPOST processing. Returns -1 when the output device is * full and the character must be retried. 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. * * Called from both the receive and transmit sides and can be called * re-entrantly. Relies on lock_kernel() still. */ 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, " ", 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) && !is_continuation(c, tty)) tty->column++; break; } } tty->driver->put_char(tty, c); return 0; } /** * opost_block - block postprocess * @tty: terminal device * @inbuf: user buffer * @nr: number of bytes * * 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. * * Called from write_chan under the tty layer write lock. */ static ssize_t opost_block(struct tty_struct * tty, const unsigned char * buf, unsigned int nr) { int space; int i; const unsigned char *cp; space = tty->driver->write_room(tty); if (!space) return 0; if (nr > space) nr = space; for (i = 0, cp = buf; i < nr; i++, cp++) { switch (*cp) { case '\n': if (O_ONLRET(tty)) tty->column = 0; if (O_ONLCR(tty)) goto break_out; tty->canon_column = tty->column; break; case '\r': if (O_ONOCR(tty) && tty->column == 0) goto break_out; if (O_OCRNL(tty)) goto break_out; tty->canon_column = tty->column = 0; break; case '\t': goto break_out; case '\b': if (tty->column > 0) tty->column--; break; default: if (O_OLCUC(tty)) goto break_out; if (!iscntrl(*cp)) tty->column++; break; } } break_out: if (tty->driver->flush_chars) tty->driver->flush_chars(tty); i = tty->driver->write(tty, buf, i); return i; } /** * put_char - write character to driver * @c: character (or part of unicode symbol) * @tty: terminal device * * Queue a byte to the driver layer for output */ static inline void put_char(unsigned char c, struct tty_struct *tty) { tty->driver->put_char(tty, c); } /** * echo_char - echo characters * @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. */ 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++; tty->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. */ static void eraser(unsigned char c, struct tty_struct *tty) { enum { ERASE, WERASE, KILL } kill_type; int head, seen_alnums, cnt; unsigned long flags; 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)) { spin_lock_irqsave(&tty->read_lock, flags); tty->read_cnt -= ((tty->read_head - tty->canon_head) & (N_TTY_BUF_SIZE - 1)); tty->read_head = tty->canon_head; spin_unlock_irqrestore(&tty->read_lock, flags); return; } if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { spin_lock_irqsave(&tty->read_lock, flags); tty->read_cnt -= ((tty->read_head - tty->canon_head) & (N_TTY_BUF_SIZE - 1)); tty->read_head = tty->canon_head; spin_unlock_irqrestore(&tty->read_lock, flags); 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; /* erase a single possibly multibyte character */ do { head = (head - 1) & (N_TTY_BUF_SIZE-1); c = tty->read_buf[head]; } while (is_continuation(c, tty) && head != tty->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 = (tty->read_head - head) & (N_TTY_BUF_SIZE-1); spin_lock_irqsave(&tty->read_lock, flags); tty->read_head = head; tty->read_cnt -= cnt; spin_unlock_irqrestore(&tty->read_lock, flags); if (L_ECHO(tty)) { if (L_ECHOPRT(tty)) { if (!tty->erasing) { put_char('\\', tty); tty->column++; tty->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); put_char(tty->read_buf[head], tty); } } else if (kill_type == ERASE && !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 if (!is_continuation(c, tty)) col++; tail = (tail+1) & (N_TTY_BUF_SIZE-1); } /* should never happen */ if (tty->column > 0x80000000) tty->column = 0; /* Now backup to that column. */ while (tty->column > col) { /* Can't use opost here. */ put_char('\b', tty); if (tty->column > 0) tty->column--; } } else { if (iscntrl(c) && L_ECHOCTL(tty)) { put_char('\b', tty); put_char(' ', tty); put_char('\b', tty); if (tty->column > 0) tty->column--; } if (!iscntrl(c) || L_ECHOCTL(tty)) { put_char('\b', tty); put_char(' ', tty); put_char('\b', tty); if (tty->column > 0) tty->column--; } } } if (kill_type == ERASE) break; } if (tty->read_head == tty->canon_head) finish_erasing(tty); } /** * isig - handle the ISIG optio * @sig: signal * @tty: terminal * @flush: force flush * * Called when a signal is being sent due to terminal input. This * may caus terminal flushing to take place according to the termios * settings and character used. Called from the driver receive_buf * path so serialized. */ static inline void isig(int sig, struct tty_struct *tty, int flush) { if (tty->pgrp) kill_pgrp(tty->pgrp, sig, 1); if (flush || !L_NOFLSH(tty)) { n_tty_flush_buffer(tty); if (tty->driver->flush_buffer) tty->driver->flush_buffer(tty); } } /** * 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) { if (I_IGNBRK(tty)) return; if (I_BRKINT(tty)) { isig(SIGINT, tty, 1); 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); } /** * 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) { char buf[64]; tty->num_overrun++; if (time_before(tty->overrun_time, jiffies - HZ) || time_after(tty->overrun_time, jiffies)) { printk(KERN_WARNING "%s: %d input overrun(s)\n", tty_name(tty, buf), tty->num_overrun); tty->overrun_time = jiffies; tty->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) { 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 if (I_INPCK(tty)) put_tty_queue('\0', tty); else put_tty_queue(c, tty); 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) { unsigned long flags; if (tty->raw) { put_tty_queue(c, tty); return; } if (tty->stopped && !tty->flow_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)) { 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: isig(signal, tty, 0); return; } } if (tty->icanon) { 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); 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); /* 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: spin_lock_irqsave(&tty->read_lock, flags); set_bit(tty->read_head, tty->read_flags); put_tty_queue_nolock(c, tty); tty->canon_head = tty->read_head; tty->canon_data++; spin_unlock_irqrestore(&tty->read_lock, flags); kill_fasync(&tty->fasync, SIGIO, POLL_IN); if (waitqueue_active(&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); } /** * 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) { set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); kill_fasync(&tty->fasync, SIGIO, POLL_OUT); } return; } /** * 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) { const unsigned char *p; char *f, flags = TTY_NORMAL; int i; char buf[64]; unsigned long cpuflags; if (!tty->read_buf) return; if (tty->real_raw) { spin_lock_irqsave(&tty->read_lock, cpuflags); i = min(N_TTY_BUF_SIZE - tty->read_cnt, N_TTY_BUF_SIZE - tty->read_head); i = min(count, i); 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(N_TTY_BUF_SIZE - tty->read_cnt, N_TTY_BUF_SIZE - tty->read_head); i = min(count, i); 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; spin_unlock_irqrestore(&tty->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("%s: unknown flag %d\n", tty_name(tty, buf), flags); break; } } if (tty->driver->flush_chars) tty->driver->flush_chars(tty); } n_tty_set_room(tty); if (!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) { 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! */ if (tty->receive_room < TTY_THRESHOLD_THROTTLE) { /* check TTY_THROTTLED first so it indicates our state */ if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) && tty->driver->throttle) tty->driver->throttle(tty); } } 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. */ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios * old) { if (!tty) return; tty->icanon = (L_ICANON(tty) != 0); if (test_bit(TTY_HW_COOK_IN, &tty->flags)) { tty->raw = 1; tty->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)) { memset(tty->process_char_map, 0, 256/8); 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); 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; } n_tty_set_room(tty); } /** * 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) { n_tty_flush_buffer(tty); if (tty->read_buf) { free_buf(tty->read_buf); tty->read_buf = 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) { if (!tty) return -EINVAL; /* This one is ugly. Currently a malloc failure here can panic */ if (!tty->read_buf) { tty->read_buf = alloc_buf(); if (!tty->read_buf) return -ENOMEM; } memset(tty->read_buf, 0, N_TTY_BUF_SIZE); reset_buffer_flags(tty); tty->column = 0; n_tty_set_termios(tty, NULL); tty->minimum_to_wake = 1; tty->closing = 0; return 0; } static inline int input_available_p(struct tty_struct *tty, int amt) { if (tty->icanon) { if (tty->canon_data) return 1; } else if (tty->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 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. * * Called under the tty->atomic_read_lock sem * */ static int copy_from_read_buf(struct tty_struct *tty, unsigned char __user **b, size_t *nr) { int retval; size_t n; unsigned long flags; retval = 0; spin_lock_irqsave(&tty->read_lock, flags); n = min(tty->read_cnt, N_TTY_BUF_SIZE - tty->read_tail); n = min(*nr, n); spin_unlock_irqrestore(&tty->read_lock, flags); if (n) { retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n); n -= retval; tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n); spin_lock_irqsave(&tty->read_lock, flags); tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1); tty->read_cnt -= n; spin_unlock_irqrestore(&tty->read_lock, flags); *b += n; *nr -= n; } return retval; } extern ssize_t redirected_tty_write(struct file *,const char *,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. */ 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) { if (!tty->pgrp) printk("read_chan: no tty->pgrp!\n"); else if (task_pgrp(current) != tty->pgrp) { if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) return -EIO; kill_pgrp(task_pgrp(current), SIGTTIN, 1); set_thread_flag(TIF_SIGPENDING); return -ERESTARTSYS; } } return 0; } /** * read_chan - 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 read_chan(struct tty_struct *tty, struct file *file, unsigned char __user *buf, size_t nr) { 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; do_it_again: if (!tty->read_buf) { printk("n_tty_read_chan: called with read_buf == NULL?!?\n"); return -EIO; } c = job_control(tty, file); if(c < 0) return c; minimum = time = 0; timeout = MAX_SCHEDULE_TIMEOUT; if (!tty->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(&tty->atomic_read_lock)) return -EAGAIN; } else { if (mutex_lock_interruptible(&tty->atomic_read_lock)) return -ERESTARTSYS; } add_wait_queue(&tty->read_wait, &wait); while (nr) { /* First test for status change. */ if (tty->packet && tty->link->ctrl_status) { unsigned char cs; if (b != buf) break; cs = tty->link->ctrl_status; tty->link->ctrl_status = 0; 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; } n_tty_set_room(tty); timeout = schedule_timeout(timeout); continue; } __set_current_state(TASK_RUNNING); /* Deal with packet mode. */ if (tty->packet && b == buf) { if (tty_put_user(tty, TIOCPKT_DATA, b++)) { retval = -EFAULT; b--; break; } nr--; } if (tty->icanon) { /* N.B. avoid overrun if nr == 0 */ while (nr && tty->read_cnt) { int eol; eol = test_and_clear_bit(tty->read_tail, tty->read_flags); c = tty->read_buf[tty->read_tail]; spin_lock_irqsave(&tty->read_lock, flags); tty->read_tail = ((tty->read_tail+1) & (N_TTY_BUF_SIZE-1)); tty->read_cnt--; if (eol) { /* this test should be redundant: * we shouldn't be reading data if * canon_data is 0 */ if (--tty->canon_data < 0) tty->canon_data = 0; } spin_unlock_irqrestore(&tty->read_lock, flags); if (!eol || (c != __DISABLED_CHAR)) { if (tty_put_user(tty, c, b++)) { retval = -EFAULT; b--; break; } nr--; } if (eol) { tty_audit_push(tty); break; } } if (retval) break; } else { int uncopied; 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. */ if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) { n_tty_set_room(tty); check_unthrottle(tty); } if (b - buf >= minimum) break; if (time) timeout = time; } mutex_unlock(&tty->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; } /** * write_chan - 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. We must be careful with N_TTY as the receive * code will echo characters, thus calling driver write methods. * * This code must be sure never to sleep through a hangup. */ static ssize_t write_chan(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; } 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 = opost_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 (opost(c, tty) < 0) break; b++; nr--; } if (tty->driver->flush_chars) tty->driver->flush_chars(tty); } else { while (nr > 0) { c = tty->driver->write(tty, b, nr); 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); return (b - buf) ? b - buf : retval; } /** * normal_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 * * FIXME: if someone changes the VMIN or discipline settings for the * terminal while another process is in poll() the poll does not * recompute the new limits. Possibly set_termios should issue * a read wakeup to fix this bug. */ static unsigned int normal_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_is_writelocked(tty) && tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS && tty->driver->write_room(tty) > 0) mask |= POLLOUT | POLLWRNORM; return mask; } struct tty_ldisc 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 = read_chan, .write = write_chan, .ioctl = n_tty_ioctl, .set_termios = n_tty_set_termios, .poll = normal_poll, .receive_buf = n_tty_receive_buf, .write_wakeup = n_tty_write_wakeup };