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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/char/n_tty.c
downloadlinux-linaro-stable-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'drivers/char/n_tty.c')
-rw-r--r--drivers/char/n_tty.c1562
1 files changed, 1562 insertions, 0 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
new file mode 100644
index 000000000000..edba5a35bf21
--- /dev/null
+++ b/drivers/char/n_tty.c
@@ -0,0 +1,1562 @@
+/*
+ * 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 write_chan 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 <asm/uaccess.h>
+#include <asm/system.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
+
+static inline unsigned char *alloc_buf(void)
+{
+ int 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 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 inline 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 semaphore 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);
+ 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 neccessary 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 > 0)
+ kill_pg(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 neccessary. 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);
+ 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:
+ 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_receive_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 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;
+}
+
+/**
+ * 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);
+ }
+
+ 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 (n_tty_receive_room(tty) < 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(&current->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 termios * 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;
+ 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_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 sem and with TTY_DONT_FLIP set
+ *
+ */
+
+static inline 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) {
+ mb();
+ retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
+ n -= retval;
+ 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 <= 0)
+ printk("read_chan: tty->pgrp <= 0!\n");
+ else if (process_group(current) != tty->pgrp) {
+ if (is_ignored(SIGTTIN) ||
+ is_orphaned_pgrp(process_group(current)))
+ return -EIO;
+ kill_pg(process_group(current), SIGTTIN, 1);
+ 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 (down_trylock(&tty->atomic_read))
+ return -EAGAIN;
+ }
+ else {
+ if (down_interruptible(&tty->atomic_read))
+ return -ERESTARTSYS;
+ }
+
+ add_wait_queue(&tty->read_wait, &wait);
+ set_bit(TTY_DONT_FLIP, &tty->flags);
+ 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 (put_user(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;
+ }
+ clear_bit(TTY_DONT_FLIP, &tty->flags);
+ timeout = schedule_timeout(timeout);
+ set_bit(TTY_DONT_FLIP, &tty->flags);
+ continue;
+ }
+ __set_current_state(TASK_RUNNING);
+
+ /* Deal with packet mode. */
+ if (tty->packet && b == buf) {
+ if (put_user(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 (put_user(c, b++)) {
+ retval = -EFAULT;
+ b--;
+ break;
+ }
+ nr--;
+ }
+ if (eol)
+ 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)
+ check_unthrottle(tty);
+
+ if (b - buf >= minimum)
+ break;
+ if (time)
+ timeout = time;
+ }
+ clear_bit(TTY_DONT_FLIP, &tty->flags);
+ up(&tty->atomic_read);
+ 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;
+
+ 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 {
+ c = tty->driver->write(tty, b, nr);
+ if (c < 0) {
+ retval = c;
+ goto break_out;
+ }
+ 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->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 = {
+ TTY_LDISC_MAGIC, /* magic */
+ "n_tty", /* name */
+ 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_poll, /* poll */
+ NULL, /* hangup */
+ n_tty_receive_buf, /* receive_buf */
+ n_tty_receive_room, /* receive_room */
+ n_tty_write_wakeup /* write_wakeup */
+};
+