kernel-ark/drivers/char/pty.c
Alan Cox a352def21a tty: Ldisc revamp
Move the line disciplines towards a conventional ->ops arrangement.  For
the moment the actual 'tty_ldisc' struct in the tty is kept as part of
the tty struct but this can then be changed if it turns out that when it
all settles down we want to refcount ldiscs separately to the tty.

Pull the ldisc code out of /proc and put it with our ldisc code.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-20 17:12:34 -07:00

467 lines
13 KiB
C

/*
* linux/drivers/char/pty.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Added support for a Unix98-style ptmx device.
* -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
* Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to
* waiting writers -- Sapan Bhatia <sapan@corewars.org>
*
*
*/
#include <linux/module.h> /* For EXPORT_SYMBOL */
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/fcntl.h>
#include <linux/string.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/bitops.h>
#include <linux/devpts_fs.h>
/* These are global because they are accessed in tty_io.c */
#ifdef CONFIG_UNIX98_PTYS
struct tty_driver *ptm_driver;
static struct tty_driver *pts_driver;
#endif
static void pty_close(struct tty_struct * tty, struct file * filp)
{
if (!tty)
return;
if (tty->driver->subtype == PTY_TYPE_MASTER) {
if (tty->count > 1)
printk("master pty_close: count = %d!!\n", tty->count);
} else {
if (tty->count > 2)
return;
}
wake_up_interruptible(&tty->read_wait);
wake_up_interruptible(&tty->write_wait);
tty->packet = 0;
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)
devpts_pty_kill(tty->index);
#endif
tty_vhangup(tty->link);
}
}
/*
* 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)
{
struct tty_struct *o_tty = tty->link;
if (!o_tty)
return;
tty_wakeup(o_tty);
set_bit(TTY_THROTTLED, &tty->flags);
}
/*
* WSH 05/24/97: modified to
* (1) use space in tty->flip instead of a shared temp buffer
* The flip buffers aren't being used for a pty, so there's lots
* of space available. The buffer is protected by a per-pty
* semaphore that should almost never come under contention.
* (2) avoid redundant copying for cases where count >> receive_room
* N.B. Calls from user space may now return an error code instead of
* a count.
*
* FIXME: Our pty_write method is called with our ldisc lock held but
* not our partners. We can't just take the other one blindly without
* risking deadlocks.
*/
static int pty_write(struct tty_struct * tty, const unsigned char *buf, int count)
{
struct tty_struct *to = tty->link;
int c;
if (!to || tty->stopped)
return 0;
c = to->receive_room;
if (c > count)
c = count;
to->ldisc.ops->receive_buf(to, buf, NULL, c);
return c;
}
static int pty_write_room(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
if (!to || tty->stopped)
return 0;
return to->receive_room;
}
/*
* WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior
* The chars_in_buffer() value is used by the ldisc select() function
* to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256).
* The pty driver chars_in_buffer() Master/Slave must behave differently:
*
* The Master side needs to allow typed-ahead commands to accumulate
* while being canonicalized, so we report "our buffer" as empty until
* some threshold is reached, and then report the count. (Any count >
* WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock
* the count returned must be 0 if no canonical data is available to be
* read. (The N_TTY ldisc.chars_in_buffer now knows this.)
*
* The Slave side passes all characters in raw mode to the Master side's
* buffer where they can be read immediately, so in this case we can
* return the true count in the buffer.
*/
static int pty_chars_in_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
int count;
/* We should get the line discipline lock for "tty->link" */
if (!to || !to->ldisc.ops->chars_in_buffer)
return 0;
/* The ldisc must report 0 if no characters available to be read */
count = to->ldisc.ops->chars_in_buffer(to);
if (tty->driver->subtype == PTY_TYPE_SLAVE) return count;
/* Master side driver ... if the other side's read buffer is less than
* half full, return 0 to allow writers to proceed; otherwise return
* the count. This leaves a comfortable margin to avoid overflow,
* and still allows half a buffer's worth of typed-ahead commands.
*/
return ((count < N_TTY_BUF_SIZE/2) ? 0 : count);
}
/* 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;
}
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
unsigned long flags;
if (!to)
return;
if (to->ldisc.ops->flush_buffer)
to->ldisc.ops->flush_buffer(to);
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);
set_bit(TTY_DO_WRITE_WAKEUP, &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);
}
static const struct tty_operations pty_ops = {
.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,
};
/* Traditional BSD devices */
#ifdef CONFIG_LEGACY_PTYS
static struct tty_driver *pty_driver, *pty_slave_driver;
static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
return pty_set_lock(tty, (int __user *) arg);
}
return -ENOIOCTLCMD;
}
static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
module_param(legacy_count, int, 0);
static const struct tty_operations pty_ops_bsd = {
.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,
};
static void __init legacy_pty_init(void)
{
if (legacy_count <= 0)
return;
pty_driver = alloc_tty_driver(legacy_count);
if (!pty_driver)
panic("Couldn't allocate pty driver");
pty_slave_driver = alloc_tty_driver(legacy_count);
if (!pty_slave_driver)
panic("Couldn't allocate pty slave driver");
pty_driver->owner = THIS_MODULE;
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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
pty_driver->other = pty_slave_driver;
tty_set_operations(pty_driver, &pty_ops);
pty_slave_driver->owner = THIS_MODULE;
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->flags = TTY_DRIVER_RESET_TERMIOS |
TTY_DRIVER_REAL_RAW;
pty_slave_driver->other = pty_driver;
tty_set_operations(pty_slave_driver, &pty_ops);
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
/*
* sysctl support for setting limits on the number of Unix98 ptys allocated.
* Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
*/
int pty_limit = NR_UNIX98_PTY_DEFAULT;
static int pty_limit_min = 0;
static int pty_limit_max = NR_UNIX98_PTY_MAX;
static struct ctl_table pty_table[] = {
{
.ctl_name = PTY_MAX,
.procname = "max",
.maxlen = sizeof(int),
.mode = 0644,
.data = &pty_limit,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &pty_limit_min,
.extra2 = &pty_limit_max,
}, {
.ctl_name = PTY_NR,
.procname = "nr",
.maxlen = sizeof(int),
.mode = 0444,
.proc_handler = &proc_dointvec,
}, {
.ctl_name = 0
}
};
static struct ctl_table pty_kern_table[] = {
{
.ctl_name = KERN_PTY,
.procname = "pty",
.mode = 0555,
.child = pty_table,
},
{}
};
static struct ctl_table pty_root_table[] = {
{
.ctl_name = CTL_KERN,
.procname = "kernel",
.mode = 0555,
.child = pty_kern_table,
},
{}
};
static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
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);
}
return -ENOIOCTLCMD;
}
static const struct tty_operations pty_unix98_ops = {
.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
};
static void __init unix98_pty_init(void)
{
ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
if (!ptm_driver)
panic("Couldn't allocate Unix98 ptm driver");
pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
if (!pts_driver)
panic("Couldn't allocate Unix98 pts driver");
ptm_driver->owner = THIS_MODULE;
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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
ptm_driver->other = pts_driver;
tty_set_operations(ptm_driver, &pty_unix98_ops);
pts_driver->owner = THIS_MODULE;
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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
pts_driver->other = ptm_driver;
tty_set_operations(pts_driver, &pty_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");
pty_table[1].data = &ptm_driver->refcount;
register_sysctl_table(pty_root_table);
}
#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);