/*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Added support for a Unix98-style ptmx device.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
*
* When reading this code see also fs/devpts. In particular note that the
* driver_data field is used by the devpts side as a binding to the devpts
* inode.
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/fcntl.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/devpts_fs.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#ifdef CONFIG_UNIX98_PTYS
static struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
static DEFINE_MUTEX(devpts_mutex);
#endif
static void pty_close(struct tty_struct *tty, struct file *filp)
{
BUG_ON(!tty);
if (tty->driver->subtype == PTY_TYPE_MASTER)
WARN_ON(tty->count > 1);
else {
if (tty->count > 2)
return;
}
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
tty->packet = 0;
/* Review - krefs on tty_link ?? */
if (!tty->link)
return;
tty->link->packet = 0;
set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
wake_up_interruptible(&tty->link->read_wait);
wake_up_interruptible(&tty->link->write_wait);
if (tty->driver->subtype == PTY_TYPE_MASTER) {
set_bit(TTY_OTHER_CLOSED, &tty->flags);
#ifdef CONFIG_UNIX98_PTYS
if (tty->driver == ptm_driver) {
mutex_lock(&devpts_mutex);
devpts_pty_kill(tty->link);
mutex_unlock(&devpts_mutex);
}
#endif
tty_unlock(tty);
tty_vhangup(tty->link);
tty_lock(tty);
}
}
/*
* The unthrottle routine is called by the line discipline to signal
* that it can receive more characters. For PTY's, the TTY_THROTTLED
* flag is always set, to force the line discipline to always call the
* unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
* characters in the queue. This is necessary since each time this
* happens, we need to wake up any sleeping processes that could be
* (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
* for the pty buffer to be drained.
*/
static void pty_unthrottle(struct tty_struct *tty)
{
tty_wakeup(tty->link);
set_bit(TTY_THROTTLED, &tty->flags);
}
/**
* pty_space - report space left for writing
* @to: tty we are writing into
*
* The tty buffers allow 64K but we sneak a peak and clip at 8K this
* allows a lot of overspill room for echo and other fun messes to
* be handled properly
*/
static int pty_space(struct tty_struct *to)
{
int n = 8192 - to->buf.memory_used;
if (n < 0)
return 0;
return n;
}
/**
* pty_write - write to a pty
* @tty: the tty we write from
* @buf: kernel buffer of data
* @count: bytes to write
*
* Our "hardware" write method. Data is coming from the ldisc which
* may be in a non sleeping state. We simply throw this at the other
* end of the link as if we were an IRQ handler receiving stuff for
* the other side of the pty/tty pair.
*/
static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
{
struct tty_struct *to = tty->link;
if (tty->stopped)
return 0;
if (c > 0) {
/* Stuff the data into the input queue of the other end */
c = tty_insert_flip_string(to, buf, c);
/* And shovel */
if (c) {
tty_flip_buffer_push(to);
tty_wakeup(tty);
}
}
return c;
}
/**
* pty_write_room - write space
* @tty: tty we are writing from
*
* Report how many bytes the ldisc can send into the queue for
* the other device.
*/
static int pty_write_room(struct tty_struct *tty)
{
if (tty->stopped)
return 0;
return pty_space(tty->link);
}
/**
* pty_chars_in_buffer - characters currently in our tx queue
* @tty: our tty
*
* Report how much we have in the transmit queue. As everything is
* instantly at the other end this is easy to implement.
*/
static int pty_chars_in_buffer(struct tty_struct *tty)
{
return 0;
}
/* Set the lock flag on a pty */
static int pty_set_lock(struct tty_struct *tty, int __user *arg)
{
int val;
if (get_user(val, arg))
return -EFAULT;
if (val)
set_bit(TTY_PTY_LOCK, &tty->flags);
else
clear_bit(TTY_PTY_LOCK, &tty->flags);
return 0;
}
/* Send a signal to the slave */
static int pty_signal(struct tty_struct *tty, int sig)
{
unsigned long flags;
struct pid *pgrp;
if (tty->link) {
spin_lock_irqsave(&tty->link->ctrl_lock, flags);
pgrp = get_pid(tty->link->pgrp);
spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
kill_pgrp(pgrp, sig, 1);
put_pid(pgrp);
}
return 0;
}
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
unsigned long flags;
if (!to)
return;
/* tty_buffer_flush(to); FIXME */
if (to->packet) {
spin_lock_irqsave(&tty->ctrl_lock, flags);
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
wake_up_interruptible(&to->read_wait);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
}
}
static int pty_open(struct tty_struct *tty, struct file *filp)
{
int retval = -ENODEV;
if (!tty || !tty->link)
goto out;
retval = -EIO;
if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
goto out;
if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
goto out;
if (tty->link->count != 1)
goto out;
clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
set_bit(TTY_THROTTLED, &tty->flags);
retval = 0;
out:
return retval;
}
static void pty_set_termios(struct tty_struct *tty,
struct ktermios *old_termios)
{
tty->termios.c_cflag &= ~(CSIZE | PARENB);
tty->termios.c_cflag |= (CS8 | CREAD);
}
/**
* pty_do_resize - resize event
* @tty: tty being resized
* @ws: window size being set.
*
* Update the termios variables and send the necessary signals to
* peform a terminal resize correctly
*/
int pty_resize(struct tty_struct *tty, struct winsize *ws)
{
struct pid *pgrp, *rpgrp;
unsigned long flags;
struct tty_struct *pty = tty->link;
/* For a PTY we need to lock the tty side */
mutex_lock(&tty->termios_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Get the PID values and reference them so we can
avoid holding the tty ctrl lock while sending signals.
We need to lock these individually however. */
spin_lock_irqsave(&tty->ctrl_lock, flags);
pgrp = get_pid(tty->pgrp);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
spin_lock_irqsave(&pty->ctrl_lock, flags);
rpgrp = get_pid(pty->pgrp);
spin_unlock_irqrestore(&pty->ctrl_lock, flags);
if (pgrp)
kill_pgrp(pgrp, SIGWINCH, 1);
if (rpgrp != pgrp && rpgrp)
kill_pgrp(rpgrp, SIGWINCH, 1);
put_pid(pgrp);
put_pid(rpgrp);
tty->winsize = *ws;
pty->winsize = *ws; /* Never used so will go away soon */
done:
mutex_unlock(&tty->termios_mutex);
return 0;
}
/**
* pty_common_install - set up the pty pair
* @driver: the pty driver
* @tty: the tty being instantiated
* @bool: legacy, true if this is BSD style
*
* Perform the initial set up for the tty/pty pair. Called from the
* tty layer when the port is first opened.
*
* Locking: the caller must hold the tty_mutex
*/
static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
bool legacy)
{
struct tty_struct *o_tty;
struct tty_port *ports[2];
int idx = tty->index;
int retval = -ENOMEM;
o_tty = alloc_tty_struct();
if (!o_tty)
goto err;
ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
if (!ports[0] || !ports[1])
goto err_free_tty;
if (!try_module_get(driver->other->owner)) {
/* This cannot in fact currently happen */
goto err_free_tty;
}
initialize_tty_struct(o_tty, driver->other, idx);
if (legacy) {
/* We always use new tty termios data so we can do this
the easy way .. */
retval = tty_init_termios(tty);
if (retval)
goto err_deinit_tty;
retval = tty_init_termios(o_tty);
if (retval)
goto err_free_termios;
driver->other->ttys[idx] = o_tty;
driver->ttys[idx] = tty;
} else {
memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
tty->termios = driver->init_termios;
memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
o_tty->termios = driver->other->init_termios;
}
/*
* Everything allocated ... set up the o_tty structure.
*/
tty_driver_kref_get(driver->other);
if (driver->subtype == PTY_TYPE_MASTER)
o_tty->count++;
/* Establish the links in both directions */
tty->link = o_tty;
o_tty->link = tty;
tty_port_init(ports[0]);
tty_port_init(ports[1]);
o_tty->port = ports[0];
tty->port = ports[1];
tty_driver_kref_get(driver);
tty->count++;
return 0;
err_free_termios:
if (legacy)
tty_free_termios(tty);
err_deinit_tty:
deinitialize_tty_struct(o_tty);
module_put(o_tty->driver->owner);
err_free_tty:
kfree(ports[0]);
kfree(ports[1]);
free_tty_struct(o_tty);
err:
return retval;
}
static void pty_cleanup(struct tty_struct *tty)
{
kfree(tty->port);
}
/* Traditional BSD devices */
#ifdef CONFIG_LEGACY_PTYS
static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
{
return pty_common_install(driver, tty, true);
}
static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
{
struct tty_struct *pair = tty->link;
driver->ttys[tty->index] = NULL;
if (pair)
pair->driver->ttys[pair->index] = NULL;
}
static int pty_bsd_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
return pty_set_lock(tty, (int __user *) arg);
case TIOCSIG: /* Send signal to other side of pty */
return pty_signal(tty, (int) arg);
}
return -ENOIOCTLCMD;
}
static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
module_param(legacy_count, int, 0);
/*
* The master side of a pty can do TIOCSPTLCK and thus
* has pty_bsd_ioctl.
*/
static const struct tty_operations master_pty_ops_bsd = {
.install = pty_install,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.ioctl = pty_bsd_ioctl,
.cleanup = pty_cleanup,
.resize = pty_resize,
.remove = pty_remove
};
static const struct tty_operations slave_pty_ops_bsd = {
.install = pty_install,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.cleanup = pty_cleanup,
.resize = pty_resize,
.remove = pty_remove
};
static void __init legacy_pty_init(void)
{
struct tty_driver *pty_driver, *pty_slave_driver;
if (legacy_count <= 0)
return;
pty_driver = tty_alloc_driver(legacy_count,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(pty_driver))
panic("Couldn't allocate pty driver");
pty_slave_driver = tty_alloc_driver(legacy_count,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(pty_slave_driver))
panic("Couldn't allocate pty slave driver");
pty_driver->driver_name = "pty_master";
pty_driver->name = "pty";
pty_driver->major = PTY_MASTER_MAJOR;
pty_driver->minor_start = 0;
pty_driver->type = TTY_DRIVER_TYPE_PTY;
pty_driver->subtype = PTY_TYPE_MASTER;
pty_driver->init_termios = tty_std_termios;
pty_driver->init_termios.c_iflag = 0;
pty_driver->init_termios.c_oflag = 0;
pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
pty_driver->init_termios.c_lflag = 0;
pty_driver->init_termios.c_ispeed = 38400;
pty_driver->init_termios.c_ospeed = 38400;
pty_driver->other = pty_slave_driver;
tty_set_operations(pty_driver, &master_pty_ops_bsd);
pty_slave_driver->driver_name = "pty_slave";
pty_slave_driver->name = "ttyp";
pty_slave_driver->major = PTY_SLAVE_MAJOR;
pty_slave_driver->minor_start = 0;
pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
pty_slave_driver->subtype = PTY_TYPE_SLAVE;
pty_slave_driver->init_termios = tty_std_termios;
pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
pty_slave_driver->init_termios.c_ispeed = 38400;
pty_slave_driver->init_termios.c_ospeed = 38400;
pty_slave_driver->other = pty_driver;
tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
if (tty_register_driver(pty_driver))
panic("Couldn't register pty driver");
if (tty_register_driver(pty_slave_driver))
panic("Couldn't register pty slave driver");
}
#else
static inline void legacy_pty_init(void) { }
#endif
/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS
static struct cdev ptmx_cdev;
static int pty_unix98_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
return pty_set_lock(tty, (int __user *)arg);
case TIOCGPTN: /* Get PT Number */
return put_user(tty->index, (unsigned int __user *)arg);
case TIOCSIG: /* Send signal to other side of pty */
return pty_signal(tty, (int) arg);
}
return -ENOIOCTLCMD;
}
/**
* ptm_unix98_lookup - find a pty master
* @driver: ptm driver
* @idx: tty index
*
* Look up a pty master device. Called under the tty_mutex for now.
* This provides our locking.
*/
static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
struct inode *ptm_inode, int idx)
{
/* Master must be open via /dev/ptmx */
return ERR_PTR(-EIO);
}
/**
* pts_unix98_lookup - find a pty slave
* @driver: pts driver
* @idx: tty index
*
* Look up a pty master device. Called under the tty_mutex for now.
* This provides our locking for the tty pointer.
*/
static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
struct inode *pts_inode, int idx)
{
struct tty_struct *tty;
mutex_lock(&devpts_mutex);
tty = devpts_get_tty(pts_inode, idx);
mutex_unlock(&devpts_mutex);
/* Master must be open before slave */
if (!tty)
return ERR_PTR(-EIO);
return tty;
}
/* We have no need to install and remove our tty objects as devpts does all
the work for us */
static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
{
return pty_common_install(driver, tty, false);
}
static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
{
}
static const struct tty_operations ptm_unix98_ops = {
.lookup = ptm_unix98_lookup,
.install = pty_unix98_install,
.remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.ioctl = pty_unix98_ioctl,
.resize = pty_resize,
.cleanup = pty_cleanup
};
static const struct tty_operations pty_unix98_ops = {
.lookup = pts_unix98_lookup,
.install = pty_unix98_install,
.remove = pty_unix98_remove,
.open = pty_open,
.close = pty_close,
.write = pty_write,
.write_room = pty_write_room,
.flush_buffer = pty_flush_buffer,
.chars_in_buffer = pty_chars_in_buffer,
.unthrottle = pty_unthrottle,
.set_termios = pty_set_termios,
.cleanup = pty_cleanup,
};
/**
* ptmx_open - open a unix 98 pty master
* @inode: inode of device file
* @filp: file pointer to tty
*
* Allocate a unix98 pty master device from the ptmx driver.
*
* Locking: tty_mutex protects the init_dev work. tty->count should
* protect the rest.
* allocated_ptys_lock handles the list of free pty numbers
*/
static int ptmx_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty;
int retval;
int index;
nonseekable_open(inode, filp);
retval = tty_alloc_file(filp);
if (retval)
return retval;
/* find a device that is not in use. */
mutex_lock(&devpts_mutex);
index = devpts_new_index(inode);
if (index < 0) {
retval = index;
mutex_unlock(&devpts_mutex);
goto err_file;
}
mutex_unlock(&devpts_mutex);
mutex_lock(&tty_mutex);
tty = tty_init_dev(ptm_driver, index);
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
goto out;
}
/* The tty returned here is locked so we can safely
drop the mutex */
mutex_unlock(&tty_mutex);
set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
tty_add_file(tty, filp);
retval = devpts_pty_new(inode, tty->link);
if (retval)
goto err_release;
retval = ptm_driver->ops->open(tty, filp);
if (retval)
goto err_release;
tty_unlock(tty);
return 0;
err_release:
tty_unlock(tty);
tty_release(inode, filp);
return retval;
out:
mutex_unlock(&tty_mutex);
devpts_kill_index(inode, index);
err_file:
tty_free_file(filp);
return retval;
}
static struct file_operations ptmx_fops;
static void __init unix98_pty_init(void)
{
ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV |
TTY_DRIVER_DEVPTS_MEM |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(ptm_driver))
panic("Couldn't allocate Unix98 ptm driver");
pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV |
TTY_DRIVER_DEVPTS_MEM |
TTY_DRIVER_DYNAMIC_ALLOC);
if (IS_ERR(pts_driver))
panic("Couldn't allocate Unix98 pts driver");
ptm_driver->driver_name = "pty_master";
ptm_driver->name = "ptm";
ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
ptm_driver->minor_start = 0;
ptm_driver->type = TTY_DRIVER_TYPE_PTY;
ptm_driver->subtype = PTY_TYPE_MASTER;
ptm_driver->init_termios = tty_std_termios;
ptm_driver->init_termios.c_iflag = 0;
ptm_driver->init_termios.c_oflag = 0;
ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
ptm_driver->init_termios.c_lflag = 0;
ptm_driver->init_termios.c_ispeed = 38400;
ptm_driver->init_termios.c_ospeed = 38400;
ptm_driver->other = pts_driver;
tty_set_operations(ptm_driver, &ptm_unix98_ops);
pts_driver->driver_name = "pty_slave";
pts_driver->name = "pts";
pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
pts_driver->minor_start = 0;
pts_driver->type = TTY_DRIVER_TYPE_PTY;
pts_driver->subtype = PTY_TYPE_SLAVE;
pts_driver->init_termios = tty_std_termios;
pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
pts_driver->init_termios.c_ispeed = 38400;
pts_driver->init_termios.c_ospeed = 38400;
pts_driver->other = ptm_driver;
tty_set_operations(pts_driver, &pty_unix98_ops);
if (tty_register_driver(ptm_driver))
panic("Couldn't register Unix98 ptm driver");
if (tty_register_driver(pts_driver))
panic("Couldn't register Unix98 pts driver");
/* Now create the /dev/ptmx special device */
tty_default_fops(&ptmx_fops);
ptmx_fops.open = ptmx_open;
cdev_init(&ptmx_cdev, &ptmx_fops);
if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
panic("Couldn't register /dev/ptmx driver\n");
device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
}
#else
static inline void unix98_pty_init(void) { }
#endif
static int __init pty_init(void)
{
legacy_pty_init();
unix98_pty_init();
return 0;
}
module_init(pty_init);
