diff options
Diffstat (limited to 'drivers/tty/tty_io.c')
| -rw-r--r-- | drivers/tty/tty_io.c | 3263 |
1 files changed, 3263 insertions, 0 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c new file mode 100644 index 00000000000..c05c5af5aa0 --- /dev/null +++ b/drivers/tty/tty_io.c @@ -0,0 +1,3263 @@ +/* + * linux/drivers/char/tty_io.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + */ + +/* + * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles + * or rs-channels. It also implements echoing, cooked mode etc. + * + * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0. + * + * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the + * tty_struct and tty_queue structures. Previously there was an array + * of 256 tty_struct's which was statically allocated, and the + * tty_queue structures were allocated at boot time. Both are now + * dynamically allocated only when the tty is open. + * + * Also restructured routines so that there is more of a separation + * between the high-level tty routines (tty_io.c and tty_ioctl.c) and + * the low-level tty routines (serial.c, pty.c, console.c). This + * makes for cleaner and more compact code. -TYT, 9/17/92 + * + * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines + * which can be dynamically activated and de-activated by the line + * discipline handling modules (like SLIP). + * + * NOTE: pay no attention to the line discipline code (yet); its + * interface is still subject to change in this version... + * -- TYT, 1/31/92 + * + * Added functionality to the OPOST tty handling. No delays, but all + * other bits should be there. + * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993. + * + * Rewrote canonical mode and added more termios flags. + * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94 + * + * Reorganized FASYNC support so mouse code can share it. + * -- ctm@ardi.com, 9Sep95 + * + * New TIOCLINUX variants added. + * -- mj@k332.feld.cvut.cz, 19-Nov-95 + * + * Restrict vt switching via ioctl() + * -- grif@cs.ucr.edu, 5-Dec-95 + * + * Move console and virtual terminal code to more appropriate files, + * implement CONFIG_VT and generalize console device interface. + * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97 + * + * Rewrote tty_init_dev and tty_release_dev to eliminate races. + * -- Bill Hawes <whawes@star.net>, June 97 + * + * Added devfs support. + * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998 + * + * Added support for a Unix98-style ptmx device. + * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998 + * + * Reduced memory usage for older ARM systems + * -- Russell King <rmk@arm.linux.org.uk> + * + * Move do_SAK() into process context. Less stack use in devfs functions. + * alloc_tty_struct() always uses kmalloc() + * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01 + */ + +#include <linux/types.h> +#include <linux/major.h> +#include <linux/errno.h> +#include <linux/signal.h> +#include <linux/fcntl.h> +#include <linux/sched.h> +#include <linux/interrupt.h> +#include <linux/tty.h> +#include <linux/tty_driver.h> +#include <linux/tty_flip.h> +#include <linux/devpts_fs.h> +#include <linux/file.h> +#include <linux/fdtable.h> +#include <linux/console.h> +#include <linux/timer.h> +#include <linux/ctype.h> +#include <linux/kd.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/slab.h> +#include <linux/poll.h> +#include <linux/proc_fs.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/smp_lock.h> +#include <linux/device.h> +#include <linux/wait.h> +#include <linux/bitops.h> +#include <linux/delay.h> +#include <linux/seq_file.h> +#include <linux/serial.h> + +#include <linux/uaccess.h> +#include <asm/system.h> + +#include <linux/kbd_kern.h> +#include <linux/vt_kern.h> +#include <linux/selection.h> + +#include <linux/kmod.h> +#include <linux/nsproxy.h> + +#undef TTY_DEBUG_HANGUP + +#define TTY_PARANOIA_CHECK 1 +#define CHECK_TTY_COUNT 1 + +struct ktermios tty_std_termios = { /* for the benefit of tty drivers */ + .c_iflag = ICRNL | IXON, + .c_oflag = OPOST | ONLCR, + .c_cflag = B38400 | CS8 | CREAD | HUPCL, + .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK | + ECHOCTL | ECHOKE | IEXTEN, + .c_cc = INIT_C_CC, + .c_ispeed = 38400, + .c_ospeed = 38400 +}; + +EXPORT_SYMBOL(tty_std_termios); + +/* This list gets poked at by procfs and various bits of boot up code. This + could do with some rationalisation such as pulling the tty proc function + into this file */ + +LIST_HEAD(tty_drivers); /* linked list of tty drivers */ + +/* Mutex to protect creating and releasing a tty. This is shared with + vt.c for deeply disgusting hack reasons */ +DEFINE_MUTEX(tty_mutex); +EXPORT_SYMBOL(tty_mutex); + +/* Spinlock to protect the tty->tty_files list */ +DEFINE_SPINLOCK(tty_files_lock); + +static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *); +static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *); +ssize_t redirected_tty_write(struct file *, const char __user *, + size_t, loff_t *); +static unsigned int tty_poll(struct file *, poll_table *); +static int tty_open(struct inode *, struct file *); +long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg); +#ifdef CONFIG_COMPAT +static long tty_compat_ioctl(struct file *file, unsigned int cmd, + unsigned long arg); +#else +#define tty_compat_ioctl NULL +#endif +static int __tty_fasync(int fd, struct file *filp, int on); +static int tty_fasync(int fd, struct file *filp, int on); +static void release_tty(struct tty_struct *tty, int idx); +static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); +static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty); + +/** + * alloc_tty_struct - allocate a tty object + * + * Return a new empty tty structure. The data fields have not + * been initialized in any way but has been zeroed + * + * Locking: none + */ + +struct tty_struct *alloc_tty_struct(void) +{ + return kzalloc(sizeof(struct tty_struct), GFP_KERNEL); +} + +/** + * free_tty_struct - free a disused tty + * @tty: tty struct to free + * + * Free the write buffers, tty queue and tty memory itself. + * + * Locking: none. Must be called after tty is definitely unused + */ + +void free_tty_struct(struct tty_struct *tty) +{ + if (tty->dev) + put_device(tty->dev); + kfree(tty->write_buf); + tty_buffer_free_all(tty); + kfree(tty); +} + +static inline struct tty_struct *file_tty(struct file *file) +{ + return ((struct tty_file_private *)file->private_data)->tty; +} + +/* Associate a new file with the tty structure */ +int tty_add_file(struct tty_struct *tty, struct file *file) +{ + struct tty_file_private *priv; + + priv = kmalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->tty = tty; + priv->file = file; + file->private_data = priv; + + spin_lock(&tty_files_lock); + list_add(&priv->list, &tty->tty_files); + spin_unlock(&tty_files_lock); + + return 0; +} + +/* Delete file from its tty */ +void tty_del_file(struct file *file) +{ + struct tty_file_private *priv = file->private_data; + + spin_lock(&tty_files_lock); + list_del(&priv->list); + spin_unlock(&tty_files_lock); + file->private_data = NULL; + kfree(priv); +} + + +#define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base) + +/** + * tty_name - return tty naming + * @tty: tty structure + * @buf: buffer for output + * + * Convert a tty structure into a name. The name reflects the kernel + * naming policy and if udev is in use may not reflect user space + * + * Locking: none + */ + +char *tty_name(struct tty_struct *tty, char *buf) +{ + if (!tty) /* Hmm. NULL pointer. That's fun. */ + strcpy(buf, "NULL tty"); + else + strcpy(buf, tty->name); + return buf; +} + +EXPORT_SYMBOL(tty_name); + +int tty_paranoia_check(struct tty_struct *tty, struct inode *inode, + const char *routine) +{ +#ifdef TTY_PARANOIA_CHECK + if (!tty) { + printk(KERN_WARNING + "null TTY for (%d:%d) in %s\n", + imajor(inode), iminor(inode), routine); + return 1; + } + if (tty->magic != TTY_MAGIC) { + printk(KERN_WARNING + "bad magic number for tty struct (%d:%d) in %s\n", + imajor(inode), iminor(inode), routine); + return 1; + } +#endif + return 0; +} + +static int check_tty_count(struct tty_struct *tty, const char *routine) +{ +#ifdef CHECK_TTY_COUNT + struct list_head *p; + int count = 0; + + spin_lock(&tty_files_lock); + list_for_each(p, &tty->tty_files) { + count++; + } + spin_unlock(&tty_files_lock); + if (tty->driver->type == TTY_DRIVER_TYPE_PTY && + tty->driver->subtype == PTY_TYPE_SLAVE && + tty->link && tty->link->count) + count++; + if (tty->count != count) { + printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) " + "!= #fd's(%d) in %s\n", + tty->name, tty->count, count, routine); + return count; + } +#endif + return 0; +} + +/** + * get_tty_driver - find device of a tty + * @dev_t: device identifier + * @index: returns the index of the tty + * + * This routine returns a tty driver structure, given a device number + * and also passes back the index number. + * + * Locking: caller must hold tty_mutex + */ + +static struct tty_driver *get_tty_driver(dev_t device, int *index) +{ + struct tty_driver *p; + + list_for_each_entry(p, &tty_drivers, tty_drivers) { + dev_t base = MKDEV(p->major, p->minor_start); + if (device < base || device >= base + p->num) + continue; + *index = device - base; + return tty_driver_kref_get(p); + } + return NULL; +} + +#ifdef CONFIG_CONSOLE_POLL + +/** + * tty_find_polling_driver - find device of a polled tty + * @name: name string to match + * @line: pointer to resulting tty line nr + * + * This routine returns a tty driver structure, given a name + * and the condition that the tty driver is capable of polled + * operation. + */ +struct tty_driver *tty_find_polling_driver(char *name, int *line) +{ + struct tty_driver *p, *res = NULL; + int tty_line = 0; + int len; + char *str, *stp; + + for (str = name; *str; str++) + if ((*str >= '0' && *str <= '9') || *str == ',') + break; + if (!*str) + return NULL; + + len = str - name; + tty_line = simple_strtoul(str, &str, 10); + + mutex_lock(&tty_mutex); + /* Search through the tty devices to look for a match */ + list_for_each_entry(p, &tty_drivers, tty_drivers) { + if (strncmp(name, p->name, len) != 0) + continue; + stp = str; + if (*stp == ',') + stp++; + if (*stp == '\0') + stp = NULL; + + if (tty_line >= 0 && tty_line < p->num && p->ops && + p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) { + res = tty_driver_kref_get(p); + *line = tty_line; + break; + } + } + mutex_unlock(&tty_mutex); + + return res; +} +EXPORT_SYMBOL_GPL(tty_find_polling_driver); +#endif + +/** + * tty_check_change - check for POSIX terminal changes + * @tty: tty to check + * + * If we try to write to, or set the state of, a terminal and we're + * not in the foreground, send a SIGTTOU. If the signal is blocked or + * ignored, go ahead and perform the operation. (POSIX 7.2) + * + * Locking: ctrl_lock + */ + +int tty_check_change(struct tty_struct *tty) +{ + unsigned long flags; + int ret = 0; + + if (current->signal->tty != tty) + return 0; + + spin_lock_irqsave(&tty->ctrl_lock, flags); + + if (!tty->pgrp) { + printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n"); + goto out_unlock; + } + if (task_pgrp(current) == tty->pgrp) + goto out_unlock; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + if (is_ignored(SIGTTOU)) + goto out; + if (is_current_pgrp_orphaned()) { + ret = -EIO; + goto out; + } + kill_pgrp(task_pgrp(current), SIGTTOU, 1); + set_thread_flag(TIF_SIGPENDING); + ret = -ERESTARTSYS; +out: + return ret; +out_unlock: + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + return ret; +} + +EXPORT_SYMBOL(tty_check_change); + +static ssize_t hung_up_tty_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + return 0; +} + +static ssize_t hung_up_tty_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + return -EIO; +} + +/* No kernel lock held - none needed ;) */ +static unsigned int hung_up_tty_poll(struct file *filp, poll_table *wait) +{ + return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM; +} + +static long hung_up_tty_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + return cmd == TIOCSPGRP ? -ENOTTY : -EIO; +} + +static long hung_up_tty_compat_ioctl(struct file *file, + unsigned int cmd, unsigned long arg) +{ + return cmd == TIOCSPGRP ? -ENOTTY : -EIO; +} + +static const struct file_operations tty_fops = { + .llseek = no_llseek, + .read = tty_read, + .write = tty_write, + .poll = tty_poll, + .unlocked_ioctl = tty_ioctl, + .compat_ioctl = tty_compat_ioctl, + .open = tty_open, + .release = tty_release, + .fasync = tty_fasync, +}; + +static const struct file_operations console_fops = { + .llseek = no_llseek, + .read = tty_read, + .write = redirected_tty_write, + .poll = tty_poll, + .unlocked_ioctl = tty_ioctl, + .compat_ioctl = tty_compat_ioctl, + .open = tty_open, + .release = tty_release, + .fasync = tty_fasync, +}; + +static const struct file_operations hung_up_tty_fops = { + .llseek = no_llseek, + .read = hung_up_tty_read, + .write = hung_up_tty_write, + .poll = hung_up_tty_poll, + .unlocked_ioctl = hung_up_tty_ioctl, + .compat_ioctl = hung_up_tty_compat_ioctl, + .release = tty_release, +}; + +static DEFINE_SPINLOCK(redirect_lock); +static struct file *redirect; + +/** + * tty_wakeup - request more data + * @tty: terminal + * + * Internal and external helper for wakeups of tty. This function + * informs the line discipline if present that the driver is ready + * to receive more output data. + */ + +void tty_wakeup(struct tty_struct *tty) +{ + struct tty_ldisc *ld; + + if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) { + ld = tty_ldisc_ref(tty); + if (ld) { + if (ld->ops->write_wakeup) + ld->ops->write_wakeup(tty); + tty_ldisc_deref(ld); + } + } + wake_up_interruptible_poll(&tty->write_wait, POLLOUT); +} + +EXPORT_SYMBOL_GPL(tty_wakeup); + +/** + * __tty_hangup - actual handler for hangup events + * @work: tty device + * + * This can be called by the "eventd" kernel thread. That is process + * synchronous but doesn't hold any locks, so we need to make sure we + * have the appropriate locks for what we're doing. + * + * The hangup event clears any pending redirections onto the hung up + * device. It ensures future writes will error and it does the needed + * line discipline hangup and signal delivery. The tty object itself + * remains intact. + * + * Locking: + * BTM + * redirect lock for undoing redirection + * file list lock for manipulating list of ttys + * tty_ldisc_lock from called functions + * termios_mutex resetting termios data + * tasklist_lock to walk task list for hangup event + * ->siglock to protect ->signal/->sighand + */ +void __tty_hangup(struct tty_struct *tty) +{ + struct file *cons_filp = NULL; + struct file *filp, *f = NULL; + struct task_struct *p; + struct tty_file_private *priv; + int closecount = 0, n; + unsigned long flags; + int refs = 0; + + if (!tty) + return; + + + spin_lock(&redirect_lock); + if (redirect && file_tty(redirect) == tty) { + f = redirect; + redirect = NULL; + } + spin_unlock(&redirect_lock); + + tty_lock(); + + /* inuse_filps is protected by the single tty lock, + this really needs to change if we want to flush the + workqueue with the lock held */ + check_tty_count(tty, "tty_hangup"); + + spin_lock(&tty_files_lock); + /* This breaks for file handles being sent over AF_UNIX sockets ? */ + list_for_each_entry(priv, &tty->tty_files, list) { + filp = priv->file; + if (filp->f_op->write == redirected_tty_write) + cons_filp = filp; + if (filp->f_op->write != tty_write) + continue; + closecount++; + __tty_fasync(-1, filp, 0); /* can't block */ + filp->f_op = &hung_up_tty_fops; + } + spin_unlock(&tty_files_lock); + + tty_ldisc_hangup(tty); + + read_lock(&tasklist_lock); + if (tty->session) { + do_each_pid_task(tty->session, PIDTYPE_SID, p) { + spin_lock_irq(&p->sighand->siglock); + if (p->signal->tty == tty) { + p->signal->tty = NULL; + /* We defer the dereferences outside fo + the tasklist lock */ + refs++; + } + if (!p->signal->leader) { + spin_unlock_irq(&p->sighand->siglock); + continue; + } + __group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p); + __group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p); + put_pid(p->signal->tty_old_pgrp); /* A noop */ + spin_lock_irqsave(&tty->ctrl_lock, flags); + if (tty->pgrp) + p->signal->tty_old_pgrp = get_pid(tty->pgrp); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + spin_unlock_irq(&p->sighand->siglock); + } while_each_pid_task(tty->session, PIDTYPE_SID, p); + } + read_unlock(&tasklist_lock); + + spin_lock_irqsave(&tty->ctrl_lock, flags); + clear_bit(TTY_THROTTLED, &tty->flags); + clear_bit(TTY_PUSH, &tty->flags); + clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); + put_pid(tty->session); + put_pid(tty->pgrp); + tty->session = NULL; + tty->pgrp = NULL; + tty->ctrl_status = 0; + set_bit(TTY_HUPPED, &tty->flags); + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + + /* Account for the p->signal references we killed */ + while (refs--) + tty_kref_put(tty); + + /* + * If one of the devices matches a console pointer, we + * cannot just call hangup() because that will cause + * tty->count and state->count to go out of sync. + * So we just call close() the right number of times. + */ + if (cons_filp) { + if (tty->ops->close) + for (n = 0; n < closecount; n++) + tty->ops->close(tty, cons_filp); + } else if (tty->ops->hangup) + (tty->ops->hangup)(tty); + /* + * We don't want to have driver/ldisc interactions beyond + * the ones we did here. The driver layer expects no + * calls after ->hangup() from the ldisc side. However we + * can't yet guarantee all that. + */ + set_bit(TTY_HUPPED, &tty->flags); + tty_ldisc_enable(tty); + + tty_unlock(); + + if (f) + fput(f); +} + +static void do_tty_hangup(struct work_struct *work) +{ + struct tty_struct *tty = + container_of(work, struct tty_struct, hangup_work); + + __tty_hangup(tty); +} + +/** + * tty_hangup - trigger a hangup event + * @tty: tty to hangup + * + * A carrier loss (virtual or otherwise) has occurred on this like + * schedule a hangup sequence to run after this event. + */ + +void tty_hangup(struct tty_struct *tty) +{ +#ifdef TTY_DEBUG_HANGUP + char buf[64]; + printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf)); +#endif + schedule_work(&tty->hangup_work); +} + +EXPORT_SYMBOL(tty_hangup); + +/** + * tty_vhangup - process vhangup + * @tty: tty to hangup + * + * The user has asked via system call for the terminal to be hung up. + * We do this synchronously so that when the syscall returns the process + * is complete. That guarantee is necessary for security reasons. + */ + +void tty_vhangup(struct tty_struct *tty) +{ +#ifdef TTY_DEBUG_HANGUP + char buf[64]; + + printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf)); +#endif + __tty_hangup(tty); +} + +EXPORT_SYMBOL(tty_vhangup); + + +/** + * tty_vhangup_self - process vhangup for own ctty + * + * Perform a vhangup on the current controlling tty + */ + +void tty_vhangup_self(void) +{ + struct tty_struct *tty; + + tty = get_current_tty(); + if (tty) { + tty_vhangup(tty); + tty_kref_put(tty); + } +} + +/** + * tty_hung_up_p - was tty hung up + * @filp: file pointer of tty + * + * Return true if the tty has been subject to a vhangup or a carrier + * loss + */ + +int tty_hung_up_p(struct file *filp) +{ + return (filp->f_op == &hung_up_tty_fops); +} + +EXPORT_SYMBOL(tty_hung_up_p); + +static void session_clear_tty(struct pid *session) +{ + struct task_struct *p; + do_each_pid_task(session, PIDTYPE_SID, p) { + proc_clear_tty(p); + } while_each_pid_task(session, PIDTYPE_SID, p); +} + +/** + * disassociate_ctty - disconnect controlling tty + * @on_exit: true if exiting so need to "hang up" the session + * + * This function is typically called only by the session leader, when + * it wants to disassociate itself from its controlling tty. + * + * It performs the following functions: + * (1) Sends a SIGHUP and SIGCONT to the foreground process group + * (2) Clears the tty from being controlling the session + * (3) Clears the controlling tty for all processes in the + * session group. + * + * The argument on_exit is set to 1 if called when a process is + * exiting; it is 0 if called by the ioctl TIOCNOTTY. + * + * Locking: + * BTM is taken for hysterical raisins, and held when + * called from no_tty(). + * tty_mutex is taken to protect tty + * ->siglock is taken to protect ->signal/->sighand + * tasklist_lock is taken to walk process list for sessions + * ->siglock is taken to protect ->signal/->sighand + */ + +void disassociate_ctty(int on_exit) +{ + struct tty_struct *tty; + struct pid *tty_pgrp = NULL; + + if (!current->signal->leader) + return; + + tty = get_current_tty(); + if (tty) { + tty_pgrp = get_pid(tty->pgrp); + if (on_exit) { + if (tty->driver->type != TTY_DRIVER_TYPE_PTY) + tty_vhangup(tty); + } + tty_kref_put(tty); + } else if (on_exit) { + struct pid *old_pgrp; + spin_lock_irq(¤t->sighand->siglock); + old_pgrp = current->signal->tty_old_pgrp; + current->signal->tty_old_pgrp = NULL; + spin_unlock_irq(¤t->sighand->siglock); + if (old_pgrp) { + kill_pgrp(old_pgrp, SIGHUP, on_exit); + kill_pgrp(old_pgrp, SIGCONT, on_exit); + put_pid(old_pgrp); + } + return; + } + if (tty_pgrp) { + kill_pgrp(tty_pgrp, SIGHUP, on_exit); + if (!on_exit) + kill_pgrp(tty_pgrp, SIGCONT, on_exit); + put_pid(tty_pgrp); + } + + spin_lock_irq(¤t->sighand->siglock); + put_pid(current->signal->tty_old_pgrp); + current->signal->tty_old_pgrp = NULL; + spin_unlock_irq(¤t->sighand->siglock); + + tty = get_current_tty(); + if (tty) { + unsigned long flags; + spin_lock_irqsave(&tty->ctrl_lock, flags); + put_pid(tty->session); + put_pid(tty->pgrp); + tty->session = NULL; + tty->pgrp = NULL; + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + tty_kref_put(tty); + } else { +#ifdef TTY_DEBUG_HANGUP + printk(KERN_DEBUG "error attempted to write to tty [0x%p]" + " = NULL", tty); +#endif + } + + /* Now clear signal->tty under the lock */ + read_lock(&tasklist_lock); + session_clear_tty(task_session(current)); + read_unlock(&tasklist_lock); +} + +/** + * + * no_tty - Ensure the current process does not have a controlling tty + */ +void no_tty(void) +{ + struct task_struct *tsk = current; + tty_lock(); + disassociate_ctty(0); + tty_unlock(); + proc_clear_tty(tsk); +} + + +/** + * stop_tty - propagate flow control + * @tty: tty to stop + * + * Perform flow control to the driver. For PTY/TTY pairs we + * must also propagate the TIOCKPKT status. May be called + * on an already stopped device and will not re-call the driver + * method. + * + * This functionality is used by both the line disciplines for + * halting incoming flow and by the driver. It may therefore be + * called from any context, may be under the tty atomic_write_lock + * but not always. + * + * Locking: + * Uses the tty control lock internally + */ + +void stop_tty(struct tty_struct *tty) +{ + unsigned long flags; + spin_lock_irqsave(&tty->ctrl_lock, flags); + if (tty->stopped) { + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + return; + } + tty->stopped = 1; + if (tty->link && tty->link->packet) { + tty->ctrl_status &= ~TIOCPKT_START; + tty->ctrl_status |= TIOCPKT_STOP; + wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); + } + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + if (tty->ops->stop) + (tty->ops->stop)(tty); +} + +EXPORT_SYMBOL(stop_tty); + +/** + * start_tty - propagate flow control + * @tty: tty to start + * + * Start a tty that has been stopped if at all possible. Perform + * any necessary wakeups and propagate the TIOCPKT status. If this + * is the tty was previous stopped and is being started then the + * driver start method is invoked and the line discipline woken. + * + * Locking: + * ctrl_lock + */ + +void start_tty(struct tty_struct *tty) +{ + unsigned long flags; + spin_lock_irqsave(&tty->ctrl_lock, flags); + if (!tty->stopped || tty->flow_stopped) { + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + return; + } + tty->stopped = 0; + if (tty->link && tty->link->packet) { + tty->ctrl_status &= ~TIOCPKT_STOP; + tty->ctrl_status |= TIOCPKT_START; + wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); + } + spin_unlock_irqrestore(&tty->ctrl_lock, flags); + if (tty->ops->start) + (tty->ops->start)(tty); + /* If we have a running line discipline it may need kicking */ + tty_wakeup(tty); +} + +EXPORT_SYMBOL(start_tty); + +/** + * tty_read - read method for tty device files + * @file: pointer to tty file + * @buf: user buffer + * @count: size of user buffer + * @ppos: unused + * + * Perform the read system call function on this terminal device. Checks + * for hung up devices before calling the line discipline method. + * + * Locking: + * Locks the line discipline internally while needed. Multiple + * read calls may be outstanding in parallel. + */ + +static ssize_t tty_read(struct file *file, char __user *buf, size_t count, + loff_t *ppos) +{ + int i; + struct inode *inode = file->f_path.dentry->d_inode; + struct tty_struct *tty = file_tty(file); + struct tty_ldisc *ld; + + if (tty_paranoia_check(tty, inode, "tty_read")) + return -EIO; + if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags))) + return -EIO; + + /* We want to wait for the line discipline to sort out in this + situation */ + ld = tty_ldisc_ref_wait(tty); + if (ld->ops->read) + i = (ld->ops->read)(tty, file, buf, count); + else + i = -EIO; + tty_ldisc_deref(ld); + if (i > 0) + inode->i_atime = current_fs_time(inode->i_sb); + return i; +} + +void tty_write_unlock(struct tty_struct *tty) +{ + mutex_unlock(&tty->atomic_write_lock); + wake_up_interruptible_poll(&tty->write_wait, POLLOUT); +} + +int tty_write_lock(struct tty_struct *tty, int ndelay) +{ + if (!mutex_trylock(&tty->atomic_write_lock)) { + if (ndelay) + return -EAGAIN; + if (mutex_lock_interruptible(&tty->atomic_write_lock)) + return -ERESTARTSYS; + } + return 0; +} + +/* + * Split writes up in sane blocksizes to avoid + * denial-of-service type attacks + */ +static inline ssize_t do_tty_write( + ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t), + struct tty_struct *tty, + struct file *file, + const char __user *buf, + size_t count) +{ + ssize_t ret, written = 0; + unsigned int chunk; + + ret = tty_write_lock(tty, file->f_flags & O_NDELAY); + if (ret < 0) + return ret; + + /* + * We chunk up writes into a temporary buffer. This + * simplifies low-level drivers immensely, since they + * don't have locking issues and user mode accesses. + * + * But if TTY_NO_WRITE_SPLIT is set, we should use a + * big chunk-size.. + * + * The default chunk-size is 2kB, because the NTTY + * layer has problems with bigger chunks. It will + * claim to be able to handle more characters than + * it actually does. + * + * FIXME: This can probably go away now except that 64K chunks + * are too likely to fail unless switched to vmalloc... + */ + chunk = 2048; + if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags)) + chunk = 65536; + if (count < chunk) + chunk = count; + + /* write_buf/write_cnt is protected by the atomic_write_lock mutex */ + if (tty->write_cnt < chunk) { + unsigned char *buf_chunk; + + if (chunk < 1024) + chunk = 1024; + + buf_chunk = kmalloc(chunk, GFP_KERNEL); + if (!buf_chunk) { + ret = -ENOMEM; + goto out; + } + kfree(tty->write_buf); + tty->write_cnt = chunk; + tty->write_buf = buf_chunk; + } + + /* Do the write .. */ + for (;;) { + size_t size = count; + if (size > chunk) + size = chunk; + ret = -EFAULT; + if (copy_from_user(tty->write_buf, buf, size)) + break; + ret = write(tty, file, tty->write_buf, size); + if (ret <= 0) + break; + written += ret; + buf += ret; + count -= ret; + if (!count) + break; + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + cond_resched(); + } + if (written) { + struct inode *inode = file->f_path.dentry->d_inode; + inode->i_mtime = current_fs_time(inode->i_sb); + ret = written; + } +out: + tty_write_unlock(tty); + return ret; +} + +/** + * tty_write_message - write a message to a certain tty, not just the console. + * @tty: the destination tty_struct + * @msg: the message to write + * + * This is used for messages that need to be redirected to a specific tty. + * We don't put it into the syslog queue right now maybe in the future if + * really needed. + * + * We must still hold the BTM and test the CLOSING flag for the moment. + */ + +void tty_write_message(struct tty_struct *tty, char *msg) +{ + if (tty) { + mutex_lock(&tty->atomic_write_lock); + tty_lock(); + if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) { + tty_unlock(); + tty->ops->write(tty, msg, strlen(msg)); + } else + tty_unlock(); + tty_write_unlock(tty); + } + return; +} + + +/** + * tty_write - write method for tty device file + * @file: tty file pointer + * @buf: user data to write + * @count: bytes to write + * @ppos: unused + * + * Write data to a tty device via the line discipline. + * + * Locking: + * Locks the line discipline as required + * Writes to the tty driver are serialized by the atomic_write_lock + * and are then processed in chunks to the device. The line discipline + * write method will not be invoked in parallel for each device. + */ + +static ssize_t tty_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct inode *inode = file->f_path.dentry->d_inode; + struct tty_struct *tty = file_tty(file); + struct tty_ldisc *ld; + ssize_t ret; + + if (tty_paranoia_check(tty, inode, "tty_write")) + return -EIO; + if (!tty || !tty->ops->write || + (test_bit(TTY_IO_ERROR, &tty->flags))) + return -EIO; + /* Short term debug to catch buggy drivers */ + if (tty->ops->write_room == NULL) + printk(KERN_ERR "tty driver %s lacks a write_room method.\n", + tty->driver->name); + ld = tty_ldisc_ref_wait(tty); + if (!ld->ops->write) + ret = -EIO; + else + ret = do_tty_write(ld->ops->write, tty, file, buf, count); + tty_ldisc_deref(ld); + return ret; +} + +ssize_t redirected_tty_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + struct file *p = NULL; + + spin_lock(&redirect_lock); + if (redirect) { + get_file(redirect); + p = redirect; + } + spin_unlock(&redirect_lock); + + if (p) { + ssize_t res; + res = vfs_write(p, buf, count, &p->f_pos); + fput(p); + return res; + } + return tty_write(file, buf, count, ppos); +} + +static char ptychar[] = "pqrstuvwxyzabcde"; + +/** + * pty_line_name - generate name for a pty + * @driver: the tty driver in use + * @index: the minor number + * @p: output buffer of at least 6 bytes + * + * Generate a name from a driver reference and write it to the output + * buffer. + * + * Locking: None + */ +static void pty_line_name(struct tty_driver *driver, int index, char *p) +{ + int i = index + driver->name_base; + /* ->name is initialized to "ttyp", but "tty" is expected */ + sprintf(p, "%s%c%x", + driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name, + ptychar[i >> 4 & 0xf], i & 0xf); +} + +/** + * tty_line_name - generate name for a tty + * @driver: the tty driver in use + * @index: the minor number + * @p: output buffer of at least 7 bytes + * + * Generate a name from a driver reference and write it to the output + * buffer. + * + * Locking: None + */ +static void tty_line_name(struct tty_driver *driver, int index, char *p) +{ + sprintf(p, "%s%d", driver->name, index + driver->name_base); +} + +/** + * tty_driver_lookup_tty() - find an existing tty, if any + * @driver: the driver for the tty + * @idx: the minor number + * + * Return the tty, if found or ERR_PTR() otherwise. + * + * Locking: tty_mutex must be held. If tty is found, the mutex must + * be held until the 'fast-open' is also done. Will change once we + * have refcounting in the driver and per driver locking + */ |