| /* |
| * 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/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->receive_room; |
| 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->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.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); |
| } |
| |
| /* 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->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->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) |
| { |
| 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); |