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linux/drivers/tty/tty_ioctl.c
Jiri Slaby ab78b0c9fa tty: cleanup tty_chars_in_buffer 
There is no need for 'else' when the 'if' part already returned. This
makes tty_chars_in_buffer similar to tty_write_room too.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-42-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-10 09:34:09 +01:00

886 lines
22 KiB
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
* which can be dynamically activated and de-activated by the line
* discipline handling modules (like SLIP).
*/
#include <linux/types.h>
#include <linux/termios.h>
#include <linux/errno.h>
#include <linux/sched/signal.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/tty.h>
#include <linux/fcntl.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/mutex.h>
#include <linux/compat.h>
#include <asm/io.h>
#include <linux/uaccess.h>
#undef TTY_DEBUG_WAIT_UNTIL_SENT
#ifdef TTY_DEBUG_WAIT_UNTIL_SENT
# define tty_debug_wait_until_sent(tty, f, args...) tty_debug(tty, f, ##args)
#else
# define tty_debug_wait_until_sent(tty, f, args...) do {} while (0)
#endif
#undef DEBUG
/*
* Internal flag options for termios setting behavior
*/
#define TERMIOS_FLUSH 1
#define TERMIOS_WAIT 2
#define TERMIOS_TERMIO 4
#define TERMIOS_OLD 8
/**
* tty_chars_in_buffer - characters pending
* @tty: terminal
*
* Return the number of bytes of data in the device private
* output queue. If no private method is supplied there is assumed
* to be no queue on the device.
*/
int tty_chars_in_buffer(struct tty_struct *tty)
{
if (tty->ops->chars_in_buffer)
return tty->ops->chars_in_buffer(tty);
return 0;
}
EXPORT_SYMBOL(tty_chars_in_buffer);
/**
* tty_write_room - write queue space
* @tty: terminal
*
* Return the number of bytes that can be queued to this device
* at the present time. The result should be treated as a guarantee
* and the driver cannot offer a value it later shrinks by more than
* the number of bytes written. If no method is provided 2K is always
* returned and data may be lost as there will be no flow control.
*/
int tty_write_room(struct tty_struct *tty)
{
if (tty->ops->write_room)
return tty->ops->write_room(tty);
return 2048;
}
EXPORT_SYMBOL(tty_write_room);
/**
* tty_driver_flush_buffer - discard internal buffer
* @tty: terminal
*
* Discard the internal output buffer for this device. If no method
* is provided then either the buffer cannot be hardware flushed or
* there is no buffer driver side.
*/
void tty_driver_flush_buffer(struct tty_struct *tty)
{
if (tty->ops->flush_buffer)
tty->ops->flush_buffer(tty);
}
EXPORT_SYMBOL(tty_driver_flush_buffer);
/**
* tty_throttle - flow control
* @tty: terminal
*
* Indicate that a tty should stop transmitting data down the stack.
* Takes the termios rwsem to protect against parallel throttle/unthrottle
* and also to ensure the driver can consistently reference its own
* termios data at this point when implementing software flow control.
*/
void tty_throttle(struct tty_struct *tty)
{
down_write(&tty->termios_rwsem);
/* check TTY_THROTTLED first so it indicates our state */
if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
tty->ops->throttle)
tty->ops->throttle(tty);
tty->flow_change = 0;
up_write(&tty->termios_rwsem);
}
EXPORT_SYMBOL(tty_throttle);
/**
* tty_unthrottle - flow control
* @tty: terminal
*
* Indicate that a tty may continue transmitting data down the stack.
* Takes the termios rwsem to protect against parallel throttle/unthrottle
* and also to ensure the driver can consistently reference its own
* termios data at this point when implementing software flow control.
*
* Drivers should however remember that the stack can issue a throttle,
* then change flow control method, then unthrottle.
*/
void tty_unthrottle(struct tty_struct *tty)
{
down_write(&tty->termios_rwsem);
if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
tty->ops->unthrottle)
tty->ops->unthrottle(tty);
tty->flow_change = 0;
up_write(&tty->termios_rwsem);
}
EXPORT_SYMBOL(tty_unthrottle);
/**
* tty_throttle_safe - flow control
* @tty: terminal
*
* Similar to tty_throttle() but will only attempt throttle
* if tty->flow_change is TTY_THROTTLE_SAFE. Prevents an accidental
* throttle due to race conditions when throttling is conditional
* on factors evaluated prior to throttling.
*
* Returns 0 if tty is throttled (or was already throttled)
*/
int tty_throttle_safe(struct tty_struct *tty)
{
int ret = 0;
mutex_lock(&tty->throttle_mutex);
if (!tty_throttled(tty)) {
if (tty->flow_change != TTY_THROTTLE_SAFE)
ret = 1;
else {
set_bit(TTY_THROTTLED, &tty->flags);
if (tty->ops->throttle)
tty->ops->throttle(tty);
}
}
mutex_unlock(&tty->throttle_mutex);
return ret;
}
/**
* tty_unthrottle_safe - flow control
* @tty: terminal
*
* Similar to tty_unthrottle() but will only attempt unthrottle
* if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
* unthrottle due to race conditions when unthrottling is conditional
* on factors evaluated prior to unthrottling.
*
* Returns 0 if tty is unthrottled (or was already unthrottled)
*/
int tty_unthrottle_safe(struct tty_struct *tty)
{
int ret = 0;
mutex_lock(&tty->throttle_mutex);
if (tty_throttled(tty)) {
if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
ret = 1;
else {
clear_bit(TTY_THROTTLED, &tty->flags);
if (tty->ops->unthrottle)
tty->ops->unthrottle(tty);
}
}
mutex_unlock(&tty->throttle_mutex);
return ret;
}
/**
* tty_wait_until_sent - wait for I/O to finish
* @tty: tty we are waiting for
* @timeout: how long we will wait
*
* Wait for characters pending in a tty driver to hit the wire, or
* for a timeout to occur (eg due to flow control)
*
* Locking: none
*/
void tty_wait_until_sent(struct tty_struct *tty, long timeout)
{
tty_debug_wait_until_sent(tty, "wait until sent, timeout=%ld\n", timeout);
if (!timeout)
timeout = MAX_SCHEDULE_TIMEOUT;
timeout = wait_event_interruptible_timeout(tty->write_wait,
!tty_chars_in_buffer(tty), timeout);
if (timeout <= 0)
return;
if (timeout == MAX_SCHEDULE_TIMEOUT)
timeout = 0;
if (tty->ops->wait_until_sent)
tty->ops->wait_until_sent(tty, timeout);
}
EXPORT_SYMBOL(tty_wait_until_sent);
/*
* Termios Helper Methods
*/
static void unset_locked_termios(struct tty_struct *tty, struct ktermios *old)
{
struct ktermios *termios = &tty->termios;
struct ktermios *locked = &tty->termios_locked;
int i;
#define NOSET_MASK(x, y, z) (x = ((x) & ~(z)) | ((y) & (z)))
NOSET_MASK(termios->c_iflag, old->c_iflag, locked->c_iflag);
NOSET_MASK(termios->c_oflag, old->c_oflag, locked->c_oflag);
NOSET_MASK(termios->c_cflag, old->c_cflag, locked->c_cflag);
NOSET_MASK(termios->c_lflag, old->c_lflag, locked->c_lflag);
termios->c_line = locked->c_line ? old->c_line : termios->c_line;
for (i = 0; i < NCCS; i++)
termios->c_cc[i] = locked->c_cc[i] ?
old->c_cc[i] : termios->c_cc[i];
/* FIXME: What should we do for i/ospeed */
}
/**
* tty_termios_copy_hw - copy hardware settings
* @new: New termios
* @old: Old termios
*
* Propagate the hardware specific terminal setting bits from
* the old termios structure to the new one. This is used in cases
* where the hardware does not support reconfiguration or as a helper
* in some cases where only minimal reconfiguration is supported
*/
void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old)
{
/* The bits a dumb device handles in software. Smart devices need
to always provide a set_termios method */
new->c_cflag &= HUPCL | CREAD | CLOCAL;
new->c_cflag |= old->c_cflag & ~(HUPCL | CREAD | CLOCAL);
new->c_ispeed = old->c_ispeed;
new->c_ospeed = old->c_ospeed;
}
EXPORT_SYMBOL(tty_termios_copy_hw);
/**
* tty_termios_hw_change - check for setting change
* @a: termios
* @b: termios to compare
*
* Check if any of the bits that affect a dumb device have changed
* between the two termios structures, or a speed change is needed.
*/
int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
{
if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed)
return 1;
if ((a->c_cflag ^ b->c_cflag) & ~(HUPCL | CREAD | CLOCAL))
return 1;
return 0;
}
EXPORT_SYMBOL(tty_termios_hw_change);
/**
* tty_set_termios - update termios values
* @tty: tty to update
* @new_termios: desired new value
*
* Perform updates to the termios values set on this terminal.
* A master pty's termios should never be set.
*
* Locking: termios_rwsem
*/
int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
{
struct ktermios old_termios;
struct tty_ldisc *ld;
WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
/*
* Perform the actual termios internal changes under lock.
*/
/* FIXME: we need to decide on some locking/ordering semantics
for the set_termios notification eventually */
down_write(&tty->termios_rwsem);
old_termios = tty->termios;
tty->termios = *new_termios;
unset_locked_termios(tty, &old_termios);
if (tty->ops->set_termios)
tty->ops->set_termios(tty, &old_termios);
else
tty_termios_copy_hw(&tty->termios, &old_termios);
ld = tty_ldisc_ref(tty);
if (ld != NULL) {
if (ld->ops->set_termios)
ld->ops->set_termios(tty, &old_termios);
tty_ldisc_deref(ld);
}
up_write(&tty->termios_rwsem);
return 0;
}
EXPORT_SYMBOL_GPL(tty_set_termios);
/**
* set_termios - set termios values for a tty
* @tty: terminal device
* @arg: user data
* @opt: option information
*
* Helper function to prepare termios data and run necessary other
* functions before using tty_set_termios to do the actual changes.
*
* Locking:
* Called functions take ldisc and termios_rwsem locks
*/
static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
{
struct ktermios tmp_termios;
struct tty_ldisc *ld;
int retval = tty_check_change(tty);
if (retval)
return retval;
down_read(&tty->termios_rwsem);
tmp_termios = tty->termios;
up_read(&tty->termios_rwsem);
if (opt & TERMIOS_TERMIO) {
if (user_termio_to_kernel_termios(&tmp_termios,
(struct termio __user *)arg))
return -EFAULT;
#ifdef TCGETS2
} else if (opt & TERMIOS_OLD) {
if (user_termios_to_kernel_termios_1(&tmp_termios,
(struct termios __user *)arg))
return -EFAULT;
} else {
if (user_termios_to_kernel_termios(&tmp_termios,
(struct termios2 __user *)arg))
return -EFAULT;
}
#else
} else if (user_termios_to_kernel_termios(&tmp_termios,
(struct termios __user *)arg))
return -EFAULT;
#endif
/* If old style Bfoo values are used then load c_ispeed/c_ospeed
* with the real speed so its unconditionally usable */
tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
tmp_termios.c_ospeed = tty_termios_baud_rate(&tmp_termios);
ld = tty_ldisc_ref(tty);
if (ld != NULL) {
if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
ld->ops->flush_buffer(tty);
tty_ldisc_deref(ld);
}
if (opt & TERMIOS_WAIT) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
return -ERESTARTSYS;
}
tty_set_termios(tty, &tmp_termios);
/* FIXME: Arguably if tmp_termios == tty->termios AND the
actual requested termios was not tmp_termios then we may
want to return an error as no user requested change has
succeeded */
return 0;
}
static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
{
down_read(&tty->termios_rwsem);
*kterm = tty->termios;
up_read(&tty->termios_rwsem);
}
static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
{
down_read(&tty->termios_rwsem);
*kterm = tty->termios_locked;
up_read(&tty->termios_rwsem);
}
static int get_termio(struct tty_struct *tty, struct termio __user *termio)
{
struct ktermios kterm;
copy_termios(tty, &kterm);
if (kernel_termios_to_user_termio(termio, &kterm))
return -EFAULT;
return 0;
}
#ifdef TIOCGETP
/*
* These are deprecated, but there is limited support..
*
* The "sg_flags" translation is a joke..
*/
static int get_sgflags(struct tty_struct *tty)
{
int flags = 0;
if (!L_ICANON(tty)) {
if (L_ISIG(tty))
flags |= 0x02; /* cbreak */
else
flags |= 0x20; /* raw */
}
if (L_ECHO(tty))
flags |= 0x08; /* echo */
if (O_OPOST(tty))
if (O_ONLCR(tty))
flags |= 0x10; /* crmod */
return flags;
}
static int get_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
{
struct sgttyb tmp;
down_read(&tty->termios_rwsem);
tmp.sg_ispeed = tty->termios.c_ispeed;
tmp.sg_ospeed = tty->termios.c_ospeed;
tmp.sg_erase = tty->termios.c_cc[VERASE];
tmp.sg_kill = tty->termios.c_cc[VKILL];
tmp.sg_flags = get_sgflags(tty);
up_read(&tty->termios_rwsem);
return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
static void set_sgflags(struct ktermios *termios, int flags)
{
termios->c_iflag = ICRNL | IXON;
termios->c_oflag = 0;
termios->c_lflag = ISIG | ICANON;
if (flags & 0x02) { /* cbreak */
termios->c_iflag = 0;
termios->c_lflag &= ~ICANON;
}
if (flags & 0x08) { /* echo */
termios->c_lflag |= ECHO | ECHOE | ECHOK |
ECHOCTL | ECHOKE | IEXTEN;
}
if (flags & 0x10) { /* crmod */
termios->c_oflag |= OPOST | ONLCR;
}
if (flags & 0x20) { /* raw */
termios->c_iflag = 0;
termios->c_lflag &= ~(ISIG | ICANON);
}
if (!(termios->c_lflag & ICANON)) {
termios->c_cc[VMIN] = 1;
termios->c_cc[VTIME] = 0;
}
}
/**
* set_sgttyb - set legacy terminal values
* @tty: tty structure
* @sgttyb: pointer to old style terminal structure
*
* Updates a terminal from the legacy BSD style terminal information
* structure.
*
* Locking: termios_rwsem
*/
static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
{
int retval;
struct sgttyb tmp;
struct ktermios termios;
retval = tty_check_change(tty);
if (retval)
return retval;
if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
return -EFAULT;
down_write(&tty->termios_rwsem);
termios = tty->termios;
termios.c_cc[VERASE] = tmp.sg_erase;
termios.c_cc[VKILL] = tmp.sg_kill;
set_sgflags(&termios, tmp.sg_flags);
/* Try and encode into Bfoo format */
#ifdef BOTHER
tty_termios_encode_baud_rate(&termios, termios.c_ispeed,
termios.c_ospeed);
#endif
up_write(&tty->termios_rwsem);
tty_set_termios(tty, &termios);
return 0;
}
#endif
#ifdef TIOCGETC
static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
{
struct tchars tmp;
down_read(&tty->termios_rwsem);
tmp.t_intrc = tty->termios.c_cc[VINTR];
tmp.t_quitc = tty->termios.c_cc[VQUIT];
tmp.t_startc = tty->termios.c_cc[VSTART];
tmp.t_stopc = tty->termios.c_cc[VSTOP];
tmp.t_eofc = tty->termios.c_cc[VEOF];
tmp.t_brkc = tty->termios.c_cc[VEOL2]; /* what is brkc anyway? */
up_read(&tty->termios_rwsem);
return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
{
struct tchars tmp;
if (copy_from_user(&tmp, tchars, sizeof(tmp)))
return -EFAULT;
down_write(&tty->termios_rwsem);
tty->termios.c_cc[VINTR] = tmp.t_intrc;
tty->termios.c_cc[VQUIT] = tmp.t_quitc;
tty->termios.c_cc[VSTART] = tmp.t_startc;
tty->termios.c_cc[VSTOP] = tmp.t_stopc;
tty->termios.c_cc[VEOF] = tmp.t_eofc;
tty->termios.c_cc[VEOL2] = tmp.t_brkc; /* what is brkc anyway? */
up_write(&tty->termios_rwsem);
return 0;
}
#endif
#ifdef TIOCGLTC
static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
{
struct ltchars tmp;
down_read(&tty->termios_rwsem);
tmp.t_suspc = tty->termios.c_cc[VSUSP];
/* what is dsuspc anyway? */
tmp.t_dsuspc = tty->termios.c_cc[VSUSP];
tmp.t_rprntc = tty->termios.c_cc[VREPRINT];
/* what is flushc anyway? */
tmp.t_flushc = tty->termios.c_cc[VEOL2];
tmp.t_werasc = tty->termios.c_cc[VWERASE];
tmp.t_lnextc = tty->termios.c_cc[VLNEXT];
up_read(&tty->termios_rwsem);
return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
}
static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
{
struct ltchars tmp;
if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
return -EFAULT;
down_write(&tty->termios_rwsem);
tty->termios.c_cc[VSUSP] = tmp.t_suspc;
/* what is dsuspc anyway? */
tty->termios.c_cc[VEOL2] = tmp.t_dsuspc;
tty->termios.c_cc[VREPRINT] = tmp.t_rprntc;
/* what is flushc anyway? */
tty->termios.c_cc[VEOL2] = tmp.t_flushc;
tty->termios.c_cc[VWERASE] = tmp.t_werasc;
tty->termios.c_cc[VLNEXT] = tmp.t_lnextc;
up_write(&tty->termios_rwsem);
return 0;
}
#endif
/**
* tty_change_softcar - carrier change ioctl helper
* @tty: tty to update
* @arg: enable/disable CLOCAL
*
* Perform a change to the CLOCAL state and call into the driver
* layer to make it visible. All done with the termios rwsem
*/
static int tty_change_softcar(struct tty_struct *tty, int arg)
{
int ret = 0;
int bit = arg ? CLOCAL : 0;
struct ktermios old;
down_write(&tty->termios_rwsem);
old = tty->termios;
tty->termios.c_cflag &= ~CLOCAL;
tty->termios.c_cflag |= bit;
if (tty->ops->set_termios)
tty->ops->set_termios(tty, &old);
if (C_CLOCAL(tty) != bit)
ret = -EINVAL;
up_write(&tty->termios_rwsem);
return ret;
}
/**
* tty_mode_ioctl - mode related ioctls
* @tty: tty for the ioctl
* @file: file pointer for the tty
* @cmd: command
* @arg: ioctl argument
*
* Perform non line discipline specific mode control ioctls. This
* is designed to be called by line disciplines to ensure they provide
* consistent mode setting.
*/
int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
struct tty_struct *real_tty;
void __user *p = (void __user *)arg;
int ret = 0;
struct ktermios kterm;
BUG_ON(file == NULL);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
real_tty = tty->link;
else
real_tty = tty;
switch (cmd) {
#ifdef TIOCGETP
case TIOCGETP:
return get_sgttyb(real_tty, (struct sgttyb __user *) arg);
case TIOCSETP:
case TIOCSETN:
return set_sgttyb(real_tty, (struct sgttyb __user *) arg);
#endif
#ifdef TIOCGETC
case TIOCGETC:
return get_tchars(real_tty, p);
case TIOCSETC:
return set_tchars(real_tty, p);
#endif
#ifdef TIOCGLTC
case TIOCGLTC:
return get_ltchars(real_tty, p);
case TIOCSLTC:
return set_ltchars(real_tty, p);
#endif
case TCSETSF:
return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_OLD);
case TCSETSW:
return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_OLD);
case TCSETS:
return set_termios(real_tty, p, TERMIOS_OLD);
#ifndef TCGETS2
case TCGETS:
copy_termios(real_tty, &kterm);
if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
ret = -EFAULT;
return ret;
#else
case TCGETS:
copy_termios(real_tty, &kterm);
if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
ret = -EFAULT;
return ret;
case TCGETS2:
copy_termios(real_tty, &kterm);
if (kernel_termios_to_user_termios((struct termios2 __user *)arg, &kterm))
ret = -EFAULT;
return ret;
case TCSETSF2:
return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT);
case TCSETSW2:
return set_termios(real_tty, p, TERMIOS_WAIT);
case TCSETS2:
return set_termios(real_tty, p, 0);
#endif
case TCGETA:
return get_termio(real_tty, p);
case TCSETAF:
return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_TERMIO);
case TCSETAW:
return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_TERMIO);
case TCSETA:
return set_termios(real_tty, p, TERMIOS_TERMIO);
#ifndef TCGETS2
case TIOCGLCKTRMIOS:
copy_termios_locked(real_tty, &kterm);
if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
ret = -EFAULT;
return ret;
case TIOCSLCKTRMIOS:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
copy_termios_locked(real_tty, &kterm);
if (user_termios_to_kernel_termios(&kterm,
(struct termios __user *) arg))
return -EFAULT;
down_write(&real_tty->termios_rwsem);
real_tty->termios_locked = kterm;
up_write(&real_tty->termios_rwsem);
return 0;
#else
case TIOCGLCKTRMIOS:
copy_termios_locked(real_tty, &kterm);
if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
ret = -EFAULT;
return ret;
case TIOCSLCKTRMIOS:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
copy_termios_locked(real_tty, &kterm);
if (user_termios_to_kernel_termios_1(&kterm,
(struct termios __user *) arg))
return -EFAULT;
down_write(&real_tty->termios_rwsem);
real_tty->termios_locked = kterm;
up_write(&real_tty->termios_rwsem);
return ret;
#endif
#ifdef TCGETX
case TCGETX:
case TCSETX:
case TCSETXW:
case TCSETXF:
return -EINVAL;
#endif
case TIOCGSOFTCAR:
copy_termios(real_tty, &kterm);
ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,
(int __user *)arg);
return ret;
case TIOCSSOFTCAR:
if (get_user(arg, (unsigned int __user *) arg))
return -EFAULT;
return tty_change_softcar(real_tty, arg);
default:
return -ENOIOCTLCMD;
}
}
EXPORT_SYMBOL_GPL(tty_mode_ioctl);
/* Caller guarantees ldisc reference is held */
static int __tty_perform_flush(struct tty_struct *tty, unsigned long arg)
{
struct tty_ldisc *ld = tty->ldisc;
switch (arg) {
case TCIFLUSH:
if (ld && ld->ops->flush_buffer) {
ld->ops->flush_buffer(tty);
tty_unthrottle(tty);
}
break;
case TCIOFLUSH:
if (ld && ld->ops->flush_buffer) {
ld->ops->flush_buffer(tty);
tty_unthrottle(tty);
}
fallthrough;
case TCOFLUSH:
tty_driver_flush_buffer(tty);
break;
default:
return -EINVAL;
}
return 0;
}
int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
{
struct tty_ldisc *ld;
int retval = tty_check_change(tty);
if (retval)
return retval;
ld = tty_ldisc_ref_wait(tty);
retval = __tty_perform_flush(tty, arg);
if (ld)
tty_ldisc_deref(ld);
return retval;
}
EXPORT_SYMBOL_GPL(tty_perform_flush);
int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
int retval;
switch (cmd) {
case TCXONC:
retval = tty_check_change(tty);
if (retval)
return retval;
switch (arg) {
case TCOOFF:
spin_lock_irq(&tty->flow_lock);
if (!tty->flow_stopped) {
tty->flow_stopped = 1;
__stop_tty(tty);
}
spin_unlock_irq(&tty->flow_lock);
break;
case TCOON:
spin_lock_irq(&tty->flow_lock);
if (tty->flow_stopped) {
tty->flow_stopped = 0;
__start_tty(tty);
}
spin_unlock_irq(&tty->flow_lock);
break;
case TCIOFF:
if (STOP_CHAR(tty) != __DISABLED_CHAR)
retval = tty_send_xchar(tty, STOP_CHAR(tty));
break;
case TCION:
if (START_CHAR(tty) != __DISABLED_CHAR)
retval = tty_send_xchar(tty, START_CHAR(tty));
break;
default:
return -EINVAL;
}
return retval;
case TCFLSH:
retval = tty_check_change(tty);
if (retval)
return retval;
return __tty_perform_flush(tty, arg);
default:
/* Try the mode commands */
return tty_mode_ioctl(tty, file, cmd, arg);
}
}
EXPORT_SYMBOL(n_tty_ioctl_helper);
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