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/*
* 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
*/
#include <linux/config.h>
#include <linux/module.h> /* For EXPORT_SYMBOL */
#include <linux/errno.h>
#include <linux/sched.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/devfs_fs_kernel.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/bitops.h>
#define BUILDING_PTY_C 1
#include <linux/devpts_fs.h>
struct pty_struct {
int magic;
wait_queue_head_t open_wait;
};
#define PTY_MAGIC 0x5001
static struct tty_driver pty_driver, pty_slave_driver;
static int pty_refcount;
/* Note: one set of tables for BSD and one for Unix98 */
static struct tty_struct *pty_table[NR_PTYS];
static struct termios *pty_termios[NR_PTYS];
static struct termios *pty_termios_locked[NR_PTYS];
static struct tty_struct *ttyp_table[NR_PTYS];
static struct termios *ttyp_termios[NR_PTYS];
static struct termios *ttyp_termios_locked[NR_PTYS];
static struct pty_struct pty_state[NR_PTYS];
#ifdef CONFIG_UNIX98_PTYS
/* These are global because they are accessed in tty_io.c */
struct tty_driver ptm_driver[UNIX98_NR_MAJORS];
struct tty_driver pts_driver[UNIX98_NR_MAJORS];
static struct tty_struct *ptm_table[UNIX98_NR_MAJORS][NR_PTYS];
static struct termios *ptm_termios[UNIX98_NR_MAJORS][NR_PTYS];
static struct termios *ptm_termios_locked[UNIX98_NR_MAJORS][NR_PTYS];
static struct tty_struct *pts_table[UNIX98_NR_MAJORS][NR_PTYS];
static struct termios *pts_termios[UNIX98_NR_MAJORS][NR_PTYS];
static struct termios *pts_termios_locked[UNIX98_NR_MAJORS][NR_PTYS];
static struct pty_struct ptm_state[UNIX98_NR_MAJORS][NR_PTYS];
#endif
#define MIN(a,b) ((a) < (b) ? (a) : (b))
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;
wake_up_interruptible(&tty->link->read_wait);
wake_up_interruptible(&tty->link->write_wait);
set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
if (tty->driver.subtype == PTY_TYPE_MASTER) {
set_bit(TTY_OTHER_CLOSED, &tty->flags);
#ifdef CONFIG_UNIX98_PTYS
{
unsigned int major = MAJOR(tty->device) - UNIX98_PTY_MASTER_MAJOR;
if ( major < UNIX98_NR_MAJORS ) {
devpts_pty_kill( MINOR(tty->device)
- tty->driver.minor_start + tty->driver.name_base );
}
}
#endif
tty_unregister_devfs (&tty->link->driver, MINOR (tty->device));
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;
if ((o_tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
o_tty->ldisc.write_wakeup)
(o_tty->ldisc.write_wakeup)(o_tty);
wake_up_interruptible(&o_tty->write_wait);
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.
*/
static int pty_write(struct tty_struct * tty, int from_user,
const unsigned char *buf, int count)
{
struct tty_struct *to = tty->link;
int c=0, n, room;
char *temp_buffer;
if (!to || tty->stopped)
return 0;
if (from_user) {
down(&tty->flip.pty_sem);
temp_buffer = &tty->flip.char_buf[0];
while (count > 0) {
/* check space so we don't copy needlessly */
n = to->ldisc.receive_room(to);
if (n > count)
n = count;
if (!n) break;
n = MIN(n, PTY_BUF_SIZE);
n -= copy_from_user(temp_buffer, buf, n);
if (!n) {
if (!c)
c = -EFAULT;
break;
}
/* check again in case the buffer filled up */
room = to->ldisc.receive_room(to);
if (n > room)
n = room;
if (!n) break;
buf += n;
c += n;
count -= n;
to->ldisc.receive_buf(to, temp_buffer, 0, n);
}
up(&tty->flip.pty_sem);
} else {
c = to->ldisc.receive_room(to);
if (c > count)
c = count;
to->ldisc.receive_buf(to, buf, 0, 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->ldisc.receive_room(to);
}
/*
* 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;
if (!to || !to->ldisc.chars_in_buffer)
return 0;
/* The ldisc must report 0 if no characters available to be read */
count = to->ldisc.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);
}
/*
* Return the device number of a Unix98 PTY (only!). This lets us open a
* master pty with the multi-headed ptmx device, then find out which
* one we got after it is open, with an ioctl.
*/
#ifdef CONFIG_UNIX98_PTYS
static int pty_get_device_number(struct tty_struct *tty, unsigned int *value)
{
unsigned int result = MINOR(tty->device)
- tty->driver.minor_start + tty->driver.name_base;
return put_user(result, value);
}
#endif
/* Set the lock flag on a pty */
static int pty_set_lock(struct tty_struct *tty, int * 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 int pty_bsd_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
if (!tty) {
printk("pty_ioctl called with NULL tty!\n");
return -EIO;
}
switch(cmd) {
case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
return pty_set_lock(tty, (int *) arg);
}
return -ENOIOCTLCMD;
}
#ifdef CONFIG_UNIX98_PTYS
static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg)
{
if (!tty) {
printk("pty_unix98_ioctl called with NULL tty!\n");
return -EIO;
}
switch(cmd) {
case TIOCGPTN: /* Get PT Number */
return pty_get_device_number(tty, (unsigned int *)arg);
}
return pty_bsd_ioctl(tty,file,cmd,arg);
}
#endif
static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
if (!to)
return;
if (to->ldisc.flush_buffer)
to->ldisc.flush_buffer(to);
if (to->packet) {
tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
wake_up_interruptible(&to->read_wait);
}
}
static int pty_open(struct tty_struct *tty, struct file * filp)
{
int retval;
int line;
struct pty_struct *pty;
retval = -ENODEV;
if (!tty || !tty->link)
goto out;
line = MINOR(tty->device) - tty->driver.minor_start;
if ((line < 0) || (line >= NR_PTYS))
goto out;
pty = (struct pty_struct *)(tty->driver.driver_state) + line;
tty->driver_data = pty;
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);
wake_up_interruptible(&pty->open_wait);
set_bit(TTY_THROTTLED, &tty->flags);
/* Register a slave for the master */
if (tty->driver.major == PTY_MASTER_MAJOR)
tty_register_devfs(&tty->link->driver,
DEVFS_FL_CURRENT_OWNER | DEVFS_FL_WAIT,
tty->link->driver.minor_start +
MINOR(tty->device)-tty->driver.minor_start);
retval = 0;
out:
return retval;
}
static void pty_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
tty->termios->c_cflag &= ~(CSIZE | PARENB);
tty->termios->c_cflag |= (CS8 | CREAD);
}
int __init pty_init(void)
{
int i;
/* Traditional BSD devices */
memset(&pty_state, 0, sizeof(pty_state));
for (i = 0; i < NR_PTYS; i++)
init_waitqueue_head(&pty_state[i].open_wait);
memset(&pty_driver, 0, sizeof(struct tty_driver));
pty_driver.magic = TTY_DRIVER_MAGIC;
pty_driver.driver_name = "pty_master";
#ifdef CONFIG_DEVFS_FS
pty_driver.name = "pty/m%d";
#else
pty_driver.name = "pty";
#endif
pty_driver.major = PTY_MASTER_MAJOR;
pty_driver.minor_start = 0;
pty_driver.num = NR_PTYS;
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.flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
pty_driver.refcount = &pty_refcount;
pty_driver.table = pty_table;
pty_driver.termios = pty_termios;
pty_driver.termios_locked = pty_termios_locked;
pty_driver.driver_state = pty_state;
pty_driver.other = &pty_slave_driver;
pty_driver.open = pty_open;
pty_driver.close = pty_close;
pty_driver.write = pty_write;
pty_driver.write_room = pty_write_room;
pty_driver.flush_buffer = pty_flush_buffer;
pty_driver.chars_in_buffer = pty_chars_in_buffer;
pty_driver.unthrottle = pty_unthrottle;
pty_driver.set_termios = pty_set_termios;
pty_slave_driver = pty_driver;
pty_slave_driver.driver_name = "pty_slave";
pty_slave_driver.proc_entry = 0;
#ifdef CONFIG_DEVFS_FS
pty_slave_driver.name = "pty/s%d";
#else
pty_slave_driver.name = "ttyp";
#endif
pty_slave_driver.subtype = PTY_TYPE_SLAVE;
pty_slave_driver.major = PTY_SLAVE_MAJOR;
pty_slave_driver.minor_start = 0;
pty_slave_driver.init_termios = tty_std_termios;
pty_slave_driver.init_termios.c_cflag = B38400 | CS8 | CREAD;
/* Slave ptys are registered when their corresponding master pty
* is opened, and unregistered when the pair is closed.
*/
pty_slave_driver.flags |= TTY_DRIVER_NO_DEVFS;
pty_slave_driver.table = ttyp_table;
pty_slave_driver.termios = ttyp_termios;
pty_slave_driver.termios_locked = ttyp_termios_locked;
pty_slave_driver.driver_state = pty_state;
pty_slave_driver.other = &pty_driver;
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");
/*
* only the master pty gets this ioctl (which is why we
* assign it here, instead of up with the rest of the
* pty_driver initialization. <cananian@alumni.princeton.edu>
*/
pty_driver.ioctl = pty_bsd_ioctl;
/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS
devfs_mk_dir (NULL, "pts", NULL);
printk("pty: %d Unix98 ptys configured\n", UNIX98_NR_MAJORS*NR_PTYS);
for ( i = 0 ; i < UNIX98_NR_MAJORS ; i++ ) {
int j;
ptm_driver[i] = pty_driver;
ptm_driver[i].name = "ptm";
ptm_driver[i].proc_entry = 0;
ptm_driver[i].major = UNIX98_PTY_MASTER_MAJOR+i;
ptm_driver[i].minor_start = 0;
ptm_driver[i].name_base = i*NR_PTYS;
ptm_driver[i].num = NR_PTYS;
ptm_driver[i].other = &pts_driver[i];
ptm_driver[i].flags |= TTY_DRIVER_NO_DEVFS;
ptm_driver[i].table = ptm_table[i];
ptm_driver[i].termios = ptm_termios[i];
ptm_driver[i].termios_locked = ptm_termios_locked[i];
ptm_driver[i].driver_state = ptm_state[i];
for (j = 0; j < NR_PTYS; j++)
init_waitqueue_head(&ptm_state[i][j].open_wait);
pts_driver[i] = pty_slave_driver;
#ifdef CONFIG_DEVFS_FS
pts_driver[i].name = "pts/%d";
#else
pts_driver[i].name = "pts";
#endif
pts_driver[i].proc_entry = 0;
pts_driver[i].major = UNIX98_PTY_SLAVE_MAJOR+i;
pts_driver[i].minor_start = 0;
pts_driver[i].name_base = i*NR_PTYS;
pts_driver[i].num = ptm_driver[i].num;
pts_driver[i].other = &ptm_driver[i];
pts_driver[i].table = pts_table[i];
pts_driver[i].termios = pts_termios[i];
pts_driver[i].termios_locked = pts_termios_locked[i];
pts_driver[i].driver_state = ptm_state[i];
ptm_driver[i].ioctl = pty_unix98_ioctl;
if (tty_register_driver(&ptm_driver[i]))
panic("Couldn't register Unix98 ptm driver major %d",
ptm_driver[i].major);
if (tty_register_driver(&pts_driver[i]))
panic("Couldn't register Unix98 pts driver major %d",
pts_driver[i].major);
}
#endif
return 0;
}
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