diff options
Diffstat (limited to 'drivers/char/pty.c')
| -rw-r--r-- | drivers/char/pty.c | 412 |
1 files changed, 412 insertions, 0 deletions
diff --git a/drivers/char/pty.c b/drivers/char/pty.c new file mode 100644 index 000000000000..da32889d22c0 --- /dev/null +++ b/drivers/char/pty.c @@ -0,0 +1,412 @@ +/* + * 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/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 <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. There is also the small matter of TTY_DONT_FLIP + */ +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->ldisc.receive_room(to); + if (c > count) + c = count; + to->ldisc.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->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; + ssize_t (*chars_in_buffer)(struct tty_struct *); + int count; + + /* We should get the line discipline lock for "tty->link" */ + if (!to || !(chars_in_buffer = to->ldisc.chars_in_buffer)) + return 0; + + /* The ldisc must report 0 if no characters available to be read */ + count = 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; + + 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 = -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 termios *old_termios) +{ + tty->termios->c_cflag &= ~(CSIZE | PARENB); + tty->termios->c_cflag |= (CS8 | CREAD); +} + +static 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 void __init legacy_pty_init(void) +{ + + pty_driver = alloc_tty_driver(NR_PTYS); + if (!pty_driver) + panic("Couldn't allocate pty driver"); + + pty_slave_driver = alloc_tty_driver(NR_PTYS); + 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->devfs_name = "pty/m"; + 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; + pty_driver->other = pty_slave_driver; + tty_set_operations(pty_driver, &pty_ops); + pty_driver->ioctl = pty_bsd_ioctl; + + pty_slave_driver->owner = THIS_MODULE; + pty_slave_driver->driver_name = "pty_slave"; + pty_slave_driver->name = "ttyp"; + pty_slave_driver->devfs_name = "pty/s"; + 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->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; + +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 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 void __init unix98_pty_init(void) +{ + devfs_mk_dir("pts"); + 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | + TTY_DRIVER_NO_DEVFS | TTY_DRIVER_DEVPTS_MEM; + ptm_driver->other = pts_driver; + tty_set_operations(ptm_driver, &pty_ops); + ptm_driver->ioctl = pty_unix98_ioctl; + + 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->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW | + TTY_DRIVER_NO_DEVFS | 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; +} +#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); |