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linux/drivers/tty/tty_io.c
Peter Hurley ece53405a1 tty: Reset c_line from driver's init_termios 
After the ldisc is released, but before the tty is destroyed, the termios
is saved (in tty_free_termios()); this termios is restored if a new
tty is created on next open(). However, the line discipline is always
reset, which is not obvious in the current method. Instead, reset
as part of the restore.

Restore the original line discipline, which may not have been N_TTY.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-01-27 15:01:44 -08:00

3685 lines
90 KiB
C
Raw Blame History

/*
* 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/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/ratelimit.h>
#include <linux/uaccess.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
#ifdef TTY_DEBUG_HANGUP
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
#else
# define tty_debug_hangup(tty, f, args...) do { } while (0)
#endif
#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);
/**
* 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
*/
static void free_tty_struct(struct tty_struct *tty)
{
tty_ldisc_deinit(tty);
put_device(tty->dev);
kfree(tty->write_buf);
tty->magic = 0xDEADDEAD;
kfree(tty);
}
static inline struct tty_struct *file_tty(struct file *file)
{
return ((struct tty_file_private *)file->private_data)->tty;
}
int tty_alloc_file(struct file *file)
{
struct tty_file_private *priv;
priv = kmalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
file->private_data = priv;
return 0;
}
/* Associate a new file with the tty structure */
void tty_add_file(struct tty_struct *tty, struct file *file)
{
struct tty_file_private *priv = file->private_data;
priv->tty = tty;
priv->file = file;
spin_lock(&tty_files_lock);
list_add(&priv->list, &tty->tty_files);
spin_unlock(&tty_files_lock);
}
/**
* tty_free_file - free file->private_data
*
* This shall be used only for fail path handling when tty_add_file was not
* called yet.
*/
void tty_free_file(struct file *file)
{
struct tty_file_private *priv = file->private_data;
file->private_data = NULL;
kfree(priv);
}
/* Delete file from its tty */
static 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);
tty_free_file(file);
}
#define TTY_NUMBER(tty) ((tty)->index + (tty)->driver->name_base)
/**
* tty_name - return tty naming
* @tty: tty structure
*
* 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
*/
const char *tty_name(const struct tty_struct *tty)
{
if (!tty) /* Hmm. NULL pointer. That's fun. */
return "NULL tty";
return tty->name;
}
EXPORT_SYMBOL(tty_name);
const char *tty_driver_name(const struct tty_struct *tty)
{
if (!tty || !tty->driver)
return "";
return tty->driver->name;
}
static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
if (!tty) {
pr_warn("(%d:%d): %s: NULL tty\n",
imajor(inode), iminor(inode), routine);
return 1;
}
if (tty->magic != TTY_MAGIC) {
pr_warn("(%d:%d): %s: bad magic number\n",
imajor(inode), iminor(inode), routine);
return 1;
}
#endif
return 0;
}
/* Caller must hold tty_lock */
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) {
tty_warn(tty, "%s: tty->count(%d) != #fd's(%d)\n",
routine, tty->count, count);
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, int sig)
{
unsigned long flags;
struct pid *pgrp, *tty_pgrp;
int ret = 0;
if (current->signal->tty != tty)
return 0;
rcu_read_lock();
pgrp = task_pgrp(current);
spin_lock_irqsave(&tty->ctrl_lock, flags);
tty_pgrp = tty->pgrp;
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
if (tty_pgrp && pgrp != tty->pgrp) {
if (is_ignored(sig)) {
if (sig == SIGTTIN)
ret = -EIO;
} else if (is_current_pgrp_orphaned())
ret = -EIO;
else {
kill_pgrp(pgrp, sig, 1);
set_thread_flag(TIF_SIGPENDING);
ret = -ERESTARTSYS;
}
}
rcu_read_unlock();
if (!tty_pgrp)
tty_warn(tty, "sig=%d, tty->pgrp == NULL!\n", sig);
return ret;
}
int tty_check_change(struct tty_struct *tty)
{
return __tty_check_change(tty, SIGTTOU);
}
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;
void proc_clear_tty(struct task_struct *p)
{
unsigned long flags;
struct tty_struct *tty;
spin_lock_irqsave(&p->sighand->siglock, flags);
tty = p->signal->tty;
p->signal->tty = NULL;
spin_unlock_irqrestore(&p->sighand->siglock, flags);
tty_kref_put(tty);
}
/**
* proc_set_tty - set the controlling terminal
*
* Only callable by the session leader and only if it does not already have
* a controlling terminal.
*
* Caller must hold: tty_lock()
* a readlock on tasklist_lock
* sighand lock
*/
static void __proc_set_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->ctrl_lock, flags);
/*
* The session and fg pgrp references will be non-NULL if
* tiocsctty() is stealing the controlling tty
*/
put_pid(tty->session);
put_pid(tty->pgrp);
tty->pgrp = get_pid(task_pgrp(current));
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
tty->session = get_pid(task_session(current));
if (current->signal->tty) {
tty_debug(tty, "current tty %s not NULL!!\n",
current->signal->tty->name);
tty_kref_put(current->signal->tty);
}
put_pid(current->signal->tty_old_pgrp);
current->signal->tty = tty_kref_get(tty);
current->signal->tty_old_pgrp = NULL;
}
static void proc_set_tty(struct tty_struct *tty)
{
spin_lock_irq(&current->sighand->siglock);
__proc_set_tty(tty);
spin_unlock_irq(&current->sighand->siglock);
}
struct tty_struct *get_current_tty(void)
{
struct tty_struct *tty;
unsigned long flags;
spin_lock_irqsave(&current->sighand->siglock, flags);
tty = tty_kref_get(current->signal->tty);
spin_unlock_irqrestore(&current->sighand->siglock, flags);
return tty;
}
EXPORT_SYMBOL_GPL(get_current_tty);
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);
}
/**
* 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_signal_session_leader - sends SIGHUP to session leader
* @tty controlling tty
* @exit_session if non-zero, signal all foreground group processes
*
* Send SIGHUP and SIGCONT to the session leader and its process group.
* Optionally, signal all processes in the foreground process group.
*
* Returns the number of processes in the session with this tty
* as their controlling terminal. This value is used to drop
* tty references for those processes.
*/
static int tty_signal_session_leader(struct tty_struct *tty, int exit_session)
{
struct task_struct *p;
int refs = 0;
struct pid *tty_pgrp = NULL;
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(&tty->ctrl_lock);
tty_pgrp = get_pid(tty->pgrp);
if (tty->pgrp)
p->signal->tty_old_pgrp = get_pid(tty->pgrp);
spin_unlock(&tty->ctrl_lock);
spin_unlock_irq(&p->sighand->siglock);
} while_each_pid_task(tty->session, PIDTYPE_SID, p);
}
read_unlock(&tasklist_lock);
if (tty_pgrp) {
if (exit_session)
kill_pgrp(tty_pgrp, SIGHUP, exit_session);
put_pid(tty_pgrp);
}
return refs;
}
/**
* __tty_hangup - actual handler for hangup events
* @work: tty device
*
* This can be called by a "kworker" 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_ldiscs_lock from called functions
* termios_rwsem resetting termios data
* tasklist_lock to walk task list for hangup event
* ->siglock to protect ->signal/->sighand
*/
static void __tty_hangup(struct tty_struct *tty, int exit_session)
{
struct file *cons_filp = NULL;
struct file *filp, *f = NULL;
struct tty_file_private *priv;
int closecount = 0, n;
int refs;
if (!tty)
return;
spin_lock(&redirect_lock);
if (redirect && file_tty(redirect) == tty) {
f = redirect;
redirect = NULL;
}
spin_unlock(&redirect_lock);
tty_lock(tty);
if (test_bit(TTY_HUPPED, &tty->flags)) {
tty_unlock(tty);
return;
}
/* 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);
refs = tty_signal_session_leader(tty, exit_session);
/* Account for the p->signal references we killed */
while (refs--)
tty_kref_put(tty);
tty_ldisc_hangup(tty);
spin_lock_irq(&tty->ctrl_lock);
clear_bit(TTY_THROTTLED, &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;
spin_unlock_irq(&tty->ctrl_lock);
/*
* 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_unlock(tty);
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, 0);
}
/**
* 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)
{
tty_debug_hangup(tty, "hangup\n");
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)
{
tty_debug_hangup(tty, "vhangup\n");
__tty_hangup(tty, 0);
}
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_vhangup_session - hangup session leader exit
* @tty: tty to hangup
*
* The session leader is exiting and hanging up its controlling terminal.
* Every process in the foreground process group is signalled SIGHUP.
*
* We do this synchronously so that when the syscall returns the process
* is complete. That guarantee is necessary for security reasons.
*/
static void tty_vhangup_session(struct tty_struct *tty)
{
tty_debug_hangup(tty, "session hangup\n");
__tty_hangup(tty, 1);
}
/**
* 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);
/**
* 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;
if (!current->signal->leader)
return;
tty = get_current_tty();
if (tty) {
if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY) {
tty_vhangup_session(tty);
} else {
struct pid *tty_pgrp = tty_get_pgrp(tty);
if (tty_pgrp) {
kill_pgrp(tty_pgrp, SIGHUP, on_exit);
if (!on_exit)
kill_pgrp(tty_pgrp, SIGCONT, on_exit);
put_pid(tty_pgrp);
}
}
tty_kref_put(tty);
} else if (on_exit) {
struct pid *old_pgrp;
spin_lock_irq(&current->sighand->siglock);
old_pgrp = current->signal->tty_old_pgrp;
current->signal->tty_old_pgrp = NULL;
spin_unlock_irq(&current->sighand->siglock);
if (old_pgrp) {
kill_pgrp(old_pgrp, SIGHUP, on_exit);
kill_pgrp(old_pgrp, SIGCONT, on_exit);
put_pid(old_pgrp);
}
return;
}
spin_lock_irq(&current->sighand->siglock);
put_pid(current->signal->tty_old_pgrp);
current->signal->tty_old_pgrp = NULL;
tty = tty_kref_get(current->signal->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
tty_debug_hangup(tty, "no current tty\n");
spin_unlock_irq(&current->sighand->siglock);
/* 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)
{
/* FIXME: Review locking here. The tty_lock never covered any race
between a new association and proc_clear_tty but possible we need
to protect against this anyway */
struct task_struct *tsk = current;
disassociate_ctty(0);
proc_clear_tty(tsk);
}
/**
* stop_tty - propagate flow control
* @tty: tty to stop
*
* Perform flow control to the driver. 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:
* flow_lock
*/
void __stop_tty(struct tty_struct *tty)
{
if (tty->stopped)
return;
tty->stopped = 1;
if (tty->ops->stop)
tty->ops->stop(tty);
}
void stop_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->flow_lock, flags);
__stop_tty(tty);
spin_unlock_irqrestore(&tty->flow_lock, flags);
}
EXPORT_SYMBOL(stop_tty);
/**
* start_tty - propagate flow control
* @tty: tty to start
*
* Start a tty that has been stopped if at all possible. If this
* tty was previous stopped and is now being started, the driver
* start method is invoked and the line discipline woken.
*
* Locking:
* flow_lock
*/
void __start_tty(struct tty_struct *tty)
{
if (!tty->stopped || tty->flow_stopped)
return;
tty->stopped = 0;
if (tty->ops->start)
tty->ops->start(tty);
tty_wakeup(tty);
}
void start_tty(struct tty_struct *tty)
{
unsigned long flags;
spin_lock_irqsave(&tty->flow_lock, flags);
__start_tty(tty);
spin_unlock_irqrestore(&tty->flow_lock, flags);
}
EXPORT_SYMBOL(start_tty);
static void tty_update_time(struct timespec *time)
{
unsigned long sec = get_seconds();
/*
* We only care if the two values differ in anything other than the
* lower three bits (i.e every 8 seconds). If so, then we can update
* the time of the tty device, otherwise it could be construded as a
* security leak to let userspace know the exact timing of the tty.
*/
if ((sec ^ time->tv_sec) & ~7)
time->tv_sec = sec;
}
/**
* 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_inode(file);
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)
tty_update_time(&inode->i_atime);
return i;
}
static void tty_write_unlock(struct tty_struct *tty)
{
mutex_unlock(&tty->atomic_write_lock);
wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
}
static 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) {
tty_update_time(&file_inode(file)->i_mtime);
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(tty);
if (tty->ops->write && tty->count > 0)
tty->ops->write(tty, msg, strlen(msg));
tty_unlock(tty);
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 tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
ssize_t ret;
if (tty_paranoia_check(tty, file_inode(file), "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)
tty_err(tty, "missing write_room method\n");
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)
p = get_file(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);
}
/**
* tty_send_xchar - send priority character
*
* Send a high priority character to the tty even if stopped
*
* Locking: none for xchar method, write ordering for write method.
*/
int tty_send_xchar(struct tty_struct *tty, char ch)
{
int was_stopped = tty->stopped;
if (tty->ops->send_xchar) {
down_read(&tty->termios_rwsem);
tty->ops->send_xchar(tty, ch);
up_read(&tty->termios_rwsem);
return 0;
}
if (tty_write_lock(tty, 0) < 0)
return -ERESTARTSYS;
down_read(&tty->termios_rwsem);
if (was_stopped)
start_tty(tty);
tty->ops->write(tty, &ch, 1);
if (was_stopped)
stop_tty(tty);
up_read(&tty->termios_rwsem);
tty_write_unlock(tty);
return 0;
}
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 ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
{
if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
return sprintf(p, "%s", driver->name);
else
return 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. If not found, return NULL or ERR_PTR() if the
* driver lookup() method returns an error.
*
* Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
*/
static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
struct inode *inode, int idx)
{
struct tty_struct *tty;
if (driver->ops->lookup)
tty = driver->ops->lookup(driver, inode, idx);
else
tty = driver->ttys[idx];
if (!IS_ERR(tty))
tty_kref_get(tty);
return tty;
}
/**
* tty_init_termios - helper for termios setup
* @tty: the tty to set up
*
* Initialise the termios structures for this tty. Thus runs under
* the tty_mutex currently so we can be relaxed about ordering.
*/
void tty_init_termios(struct tty_struct *tty)
{
struct ktermios *tp;
int idx = tty->index;
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
tty->termios = tty->driver->init_termios;
else {
/* Check for lazy saved data */
tp = tty->driver->termios[idx];
if (tp != NULL) {
tty->termios = *tp;
tty->termios.c_line = tty->driver->init_termios.c_line;
} else
tty->termios = tty->driver->init_termios;
}
/* Compatibility until drivers always set this */
tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
}
EXPORT_SYMBOL_GPL(tty_init_termios);
int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
{
tty_init_termios(tty);
tty_driver_kref_get(driver);
tty->count++;
driver->ttys[tty->index] = tty;
return 0;
}
EXPORT_SYMBOL_GPL(tty_standard_install);
/**
* tty_driver_install_tty() - install a tty entry in the driver
* @driver: the driver for the tty
* @tty: the tty
*
* Install a tty object into the driver tables. The tty->index field
* will be set by the time this is called. This method is responsible
* for ensuring any need additional structures are allocated and
* configured.
*
* Locking: tty_mutex for now
*/
static int tty_driver_install_tty(struct tty_driver *driver,
struct tty_struct *tty)
{
return driver->ops->install ? driver->ops->install(driver, tty) :
tty_standard_install(driver, tty);
}
/**
* tty_driver_remove_tty() - remove a tty from the driver tables
* @driver: the driver for the tty
* @idx: the minor number
*
* Remvoe a tty object from the driver tables. The tty->index field
* will be set by the time this is called.
*
* Locking: tty_mutex for now
*/
static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
{
if (driver->ops->remove)
driver->ops->remove(driver, tty);
else
driver->ttys[tty->index] = NULL;
}
/*
* tty_reopen() - fast re-open of an open tty
* @tty - the tty to open
*
* Return 0 on success, -errno on error.
* Re-opens on master ptys are not allowed and return -EIO.
*
* Locking: Caller must hold tty_lock
*/
static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;
if (driver->type == TTY_DRIVER_TYPE_PTY &&
driver->subtype == PTY_TYPE_MASTER)
return -EIO;
if (!tty->count)
return -EAGAIN;
if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
return -EBUSY;
tty->count++;
WARN_ON(!tty->ldisc);
return 0;
}
/**
* tty_init_dev - initialise a tty device
* @driver: tty driver we are opening a device on
* @idx: device index
* @ret_tty: returned tty structure
*
* Prepare a tty device. This may not be a "new" clean device but
* could also be an active device. The pty drivers require special
* handling because of this.
*
* Locking:
* The function is called under the tty_mutex, which
* protects us from the tty struct or driver itself going away.
*
* On exit the tty device has the line discipline attached and
* a reference count of 1. If a pair was created for pty/tty use
* and the other was a pty master then it too has a reference count of 1.
*
* WSH 06/09/97: Rewritten to remove races and properly clean up after a
* failed open. The new code protects the open with a mutex, so it's
* really quite straightforward. The mutex locking can probably be
* relaxed for the (most common) case of reopening a tty.
*/
struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
int retval;
/*
* First time open is complex, especially for PTY devices.
* This code guarantees that either everything succeeds and the
* TTY is ready for operation, or else the table slots are vacated
* and the allocated memory released. (Except that the termios
* and locked termios may be retained.)
*/
if (!try_module_get(driver->owner))
return ERR_PTR(-ENODEV);
tty = alloc_tty_struct(driver, idx);
if (!tty) {
retval = -ENOMEM;
goto err_module_put;
}
tty_lock(tty);
retval = tty_driver_install_tty(driver, tty);
if (retval < 0)
goto err_free_tty;
if (!tty->port)
tty->port = driver->ports[idx];
WARN_RATELIMIT(!tty->port,
"%s: %s driver does not set tty->port. This will crash the kernel later. Fix the driver!\n",
__func__, tty->driver->name);
tty->port->itty = tty;
/*
* Structures all installed ... call the ldisc open routines.
* If we fail here just call release_tty to clean up. No need
* to decrement the use counts, as release_tty doesn't care.
*/
retval = tty_ldisc_setup(tty, tty->link);
if (retval)
goto err_release_tty;
/* Return the tty locked so that it cannot vanish under the caller */
return tty;
err_free_tty:
tty_unlock(tty);
free_tty_struct(tty);
err_module_put:
module_put(driver->owner);
return ERR_PTR(retval);
/* call the tty release_tty routine to clean out this slot */
err_release_tty:
tty_unlock(tty);
tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
retval, idx);
release_tty(tty, idx);
return ERR_PTR(retval);
}
static void tty_free_termios(struct tty_struct *tty)
{
struct ktermios *tp;
int idx = tty->index;
/* If the port is going to reset then it has no termios to save */
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
return;
/* Stash the termios data */
tp = tty->driver->termios[idx];
if (tp == NULL) {
tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (tp == NULL)
return;
tty->driver->termios[idx] = tp;
}
*tp = tty->termios;
}
/**
* tty_flush_works - flush all works of a tty/pty pair
* @tty: tty device to flush works for (or either end of a pty pair)
*
* Sync flush all works belonging to @tty (and the 'other' tty).
*/
static void tty_flush_works(struct tty_struct *tty)
{
flush_work(&tty->SAK_work);
flush_work(&tty->hangup_work);
if (tty->link) {
flush_work(&tty->link->SAK_work);
flush_work(&tty->link->hangup_work);
}
}
/**
* release_one_tty - release tty structure memory
* @kref: kref of tty we are obliterating
*
* Releases memory associated with a tty structure, and clears out the
* driver table slots. This function is called when a device is no longer
* in use. It also gets called when setup of a device fails.
*
* Locking:
* takes the file list lock internally when working on the list
* of ttys that the driver keeps.
*
* This method gets called from a work queue so that the driver private
* cleanup ops can sleep (needed for USB at least)
*/
static void release_one_tty(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, hangup_work);
struct tty_driver *driver = tty->driver;
struct module *owner = driver->owner;
if (tty->ops->cleanup)
tty->ops->cleanup(tty);
tty->magic = 0;
tty_driver_kref_put(driver);
module_put(owner);
spin_lock(&tty_files_lock);
list_del_init(&tty->tty_files);
spin_unlock(&tty_files_lock);
put_pid(tty->pgrp);
put_pid(tty->session);
free_tty_struct(tty);
}
static void queue_release_one_tty(struct kref *kref)
{
struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
/* The hangup queue is now free so we can reuse it rather than
waste a chunk of memory for each port */
INIT_WORK(&tty->hangup_work, release_one_tty);
schedule_work(&tty->hangup_work);
}
/**
* tty_kref_put - release a tty kref
* @tty: tty device
*
* Release a reference to a tty device and if need be let the kref
* layer destruct the object for us
*/
void tty_kref_put(struct tty_struct *tty)
{
if (tty)
kref_put(&tty->kref, queue_release_one_tty);
}
EXPORT_SYMBOL(tty_kref_put);
/**
* release_tty - release tty structure memory
*
* Release both @tty and a possible linked partner (think pty pair),
* and decrement the refcount of the backing module.
*
* Locking:
* tty_mutex
* takes the file list lock internally when working on the list
* of ttys that the driver keeps.
*
*/
static void release_tty(struct tty_struct *tty, int idx)
{
/* This should always be true but check for the moment */
WARN_ON(tty->index != idx);
WARN_ON(!mutex_is_locked(&tty_mutex));
if (tty->ops->shutdown)
tty->ops->shutdown(tty);
tty_free_termios(tty);
tty_driver_remove_tty(tty->driver, tty);
tty->port->itty = NULL;
if (tty->link)
tty->link->port->itty = NULL;
tty_buffer_cancel_work(tty->port);
tty_kref_put(tty->link);
tty_kref_put(tty);
}
/**
* tty_release_checks - check a tty before real release
* @tty: tty to check
* @o_tty: link of @tty (if any)
* @idx: index of the tty
*
* Performs some paranoid checking before true release of the @tty.
* This is a no-op unless TTY_PARANOIA_CHECK is defined.
*/
static int tty_release_checks(struct tty_struct *tty, int idx)
{
#ifdef TTY_PARANOIA_CHECK
if (idx < 0 || idx >= tty->driver->num) {
tty_debug(tty, "bad idx %d\n", idx);
return -1;
}
/* not much to check for devpts */
if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
return 0;
if (tty != tty->driver->ttys[idx]) {
tty_debug(tty, "bad driver table[%d] = %p\n",
idx, tty->driver->ttys[idx]);
return -1;
}
if (tty->driver->other) {
struct tty_struct *o_tty = tty->link;
if (o_tty != tty->driver->other->ttys[idx]) {
tty_debug(tty, "bad other table[%d] = %p\n",
idx, tty->driver->other->ttys[idx]);
return -1;
}
if (o_tty->link != tty) {
tty_debug(tty, "bad link = %p\n", o_tty->link);
return -1;
}
}
#endif
return 0;
}
/**
* tty_release - vfs callback for close
* @inode: inode of tty
* @filp: file pointer for handle to tty
*
* Called the last time each file handle is closed that references
* this tty. There may however be several such references.
*
* Locking:
* Takes bkl. See tty_release_dev
*
* Even releasing the tty structures is a tricky business.. We have
* to be very careful that the structures are all released at the
* same time, as interrupts might otherwise get the wrong pointers.
*
* WSH 09/09/97: rewritten to avoid some nasty race conditions that could
* lead to double frees or releasing memory still in use.
*/
int tty_release(struct inode *inode, struct file *filp)
{
struct tty_struct *tty = file_tty(filp);
struct tty_struct *o_tty = NULL;
int do_sleep, final;
int idx;
long timeout = 0;
int once = 1;
if (tty_paranoia_check(tty, inode, __func__))
return 0;
tty_lock(tty);
check_tty_count(tty, __func__);
__tty_fasync(-1, filp, 0);
idx = tty->index;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
o_tty = tty->link;
if (tty_release_checks(tty, idx)) {
tty_unlock(tty);
return 0;
}
tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
if (tty->ops->close)
tty->ops->close(tty, filp);
/* If tty is pty master, lock the slave pty (stable lock order) */
tty_lock_slave(o_tty);
/*
* Sanity check: if tty->count is going to zero, there shouldn't be
* any waiters on tty->read_wait or tty->write_wait. We test the
* wait queues and kick everyone out _before_ actually starting to
* close. This ensures that we won't block while releasing the tty
* structure.
*
* The test for the o_tty closing is necessary, since the master and
* slave sides may close in any order. If the slave side closes out
* first, its count will be one, since the master side holds an open.
* Thus this test wouldn't be triggered at the time the slave closed,
* so we do it now.
*/
while (1) {
do_sleep = 0;
if (tty->count <= 1) {
if (waitqueue_active(&tty->read_wait)) {
wake_up_poll(&tty->read_wait, POLLIN);
do_sleep++;
}
if (waitqueue_active(&tty->write_wait)) {
wake_up_poll(&tty->write_wait, POLLOUT);
do_sleep++;
}
}
if (o_tty && o_tty->count <= 1) {
if (waitqueue_active(&o_tty->read_wait)) {
wake_up_poll(&o_tty->read_wait, POLLIN);
do_sleep++;
}
if (waitqueue_active(&o_tty->write_wait)) {
wake_up_poll(&o_tty->write_wait, POLLOUT);
do_sleep++;
}
}
if (!do_sleep)
break;
if (once) {
once = 0;
tty_warn(tty, "read/write wait queue active!\n");
}
schedule_timeout_killable(timeout);
if (timeout < 120 * HZ)
timeout = 2 * timeout + 1;
else
timeout = MAX_SCHEDULE_TIMEOUT;
}
if (o_tty) {
if (--o_tty->count < 0) {
tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
o_tty->count = 0;
}
}
if (--tty->count < 0) {
tty_warn(tty, "bad tty->count (%d)\n", tty->count);
tty->count = 0;
}
/*
* We've decremented tty->count, so we need to remove this file
* descriptor off the tty->tty_files list; this serves two
* purposes:
* - check_tty_count sees the correct number of file descriptors
* associated with this tty.
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
tty_del_file(filp);
/*
* Perform some housekeeping before deciding whether to return.
*
* If _either_ side is closing, make sure there aren't any
* processes that still think tty or o_tty is their controlling
* tty.
*/
if (!tty->count) {
read_lock(&tasklist_lock);
session_clear_tty(tty->session);
if (o_tty)
session_clear_tty(o_tty->session);
read_unlock(&tasklist_lock);
}
/* check whether both sides are closing ... */
final = !tty->count && !(o_tty && o_tty->count);
tty_unlock_slave(o_tty);
tty_unlock(tty);
/* At this point, the tty->count == 0 should ensure a dead tty
cannot be re-opened by a racing opener */
if (!final)
return 0;
tty_debug_hangup(tty, "final close\n");
/*
* Ask the line discipline code to release its structures
*/
tty_ldisc_release(tty);
/* Wait for pending work before tty destruction commmences */
tty_flush_works(tty);
tty_debug_hangup(tty, "freeing structure\n");
/*
* The release_tty function takes care of the details of clearing
* the slots and preserving the termios structure. The tty_unlock_pair
* should be safe as we keep a kref while the tty is locked (so the
* unlock never unlocks a freed tty).
*/
mutex_lock(&tty_mutex);
release_tty(tty, idx);
mutex_unlock(&tty_mutex);
return 0;
}
/**
* tty_open_current_tty - get locked tty of current task
* @device: device number
* @filp: file pointer to tty
* @return: locked tty of the current task iff @device is /dev/tty
*
* Performs a re-open of the current task's controlling tty.
*
* We cannot return driver and index like for the other nodes because
* devpts will not work then. It expects inodes to be from devpts FS.
*/
static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
{
struct tty_struct *tty;
int retval;
if (device != MKDEV(TTYAUX_MAJOR, 0))
return NULL;
tty = get_current_tty();
if (!tty)
return ERR_PTR(-ENXIO);
filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
/* noctty = 1; */
tty_lock(tty);
tty_kref_put(tty); /* safe to drop the kref now */
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval);
}
return tty;
}
/**
* tty_lookup_driver - lookup a tty driver for a given device file
* @device: device number
* @filp: file pointer to tty
* @noctty: set if the device should not become a controlling tty
* @index: index for the device in the @return driver
* @return: driver for this inode (with increased refcount)
*
* If @return is not erroneous, the caller is responsible to decrement the
* refcount by tty_driver_kref_put.
*
* Locking: tty_mutex protects get_tty_driver
*/
static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
int *index)
{
struct tty_driver *driver;
switch (device) {
#ifdef CONFIG_VT
case MKDEV(TTY_MAJOR, 0): {
extern struct tty_driver *console_driver;
driver = tty_driver_kref_get(console_driver);
*index = fg_console;
break;
}
#endif
case MKDEV(TTYAUX_MAJOR, 1): {
struct tty_driver *console_driver = console_device(index);
if (console_driver) {
driver = tty_driver_kref_get(console_driver);
if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
break;
}
}
return ERR_PTR(-ENODEV);
}
default:
driver = get_tty_driver(device, index);
if (!driver)
return ERR_PTR(-ENODEV);
break;
}
return driver;
}
/**
* tty_open_by_driver - open a tty device
* @device: dev_t of device to open
* @inode: inode of device file
* @filp: file pointer to tty
*
* Performs the driver lookup, checks for a reopen, or otherwise
* performs the first-time tty initialization.
*
* Returns the locked initialized or re-opened &tty_struct
*
* Claims the global tty_mutex to serialize:
* - concurrent first-time tty initialization
* - concurrent tty driver removal w/ lookup
* - concurrent tty removal from driver table
*/
static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
struct file *filp)
{
struct tty_struct *tty;
struct tty_driver *driver = NULL;
int index = -1;
int retval;
mutex_lock(&tty_mutex);
driver = tty_lookup_driver(device, filp, &index);
if (IS_ERR(driver)) {
mutex_unlock(&tty_mutex);
return ERR_CAST(driver);
}
/* check whether we're reopening an existing tty */
tty = tty_driver_lookup_tty(driver, inode, index);
if (IS_ERR(tty)) {
mutex_unlock(&tty_mutex);
goto out;
}
if (tty) {
mutex_unlock(&tty_mutex);
retval = tty_lock_interruptible(tty);
if (retval) {
if (retval == -EINTR)
retval = -ERESTARTSYS;
tty = ERR_PTR(retval);
goto out;
}
/* safe to drop the kref from tty_driver_lookup_tty() */
tty_kref_put(tty);
retval = tty_reopen(tty);
if (retval < 0) {
tty_unlock(tty);
tty = ERR_PTR(retval);
}
} else { /* Returns with the tty_lock held for now */
tty = tty_init_dev(driver, index);
mutex_unlock(&tty_mutex);
}
out:
tty_driver_kref_put(driver);
return tty;
}
/**
* tty_open - open a tty device
* @inode: inode of device file
* @filp: file pointer to tty
*
* tty_open and tty_release keep up the tty count that contains the
* number of opens done on a tty. We cannot use the inode-count, as
* different inodes might point to the same tty.
*
* Open-counting is needed for pty masters, as well as for keeping
* track of serial lines: DTR is dropped when the last close happens.
* (This is not done solely through tty->count, now. - Ted 1/27/92)
*
* The termios state of a pty is reset on first open so that
* settings don't persist across reuse.
*
* Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
* tty->count should protect the rest.
* ->siglock protects ->signal/->sighand
*
* Note: the tty_unlock/lock cases without a ref are only safe due to
* tty_mutex
*/
static int tty_open(struct inode *inode, struct file *filp)
{
struct tty_struct *tty;
int noctty, retval;
dev_t device = inode->i_rdev;
unsigned saved_flags = filp->f_flags;
nonseekable_open(inode, filp);
retry_open:
retval = tty_alloc_file(filp);
if (retval)
return -ENOMEM;
tty = tty_open_current_tty(device, filp);
if (!tty)
tty = tty_open_by_driver(device, inode, filp);
if (IS_ERR(tty)) {
tty_free_file(filp);
retval = PTR_ERR(tty);
if (retval != -EAGAIN || signal_pending(current))
return retval;
schedule();
goto retry_open;
}
tty_add_file(tty, filp);
check_tty_count(tty, __func__);
tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
if (tty->ops->open)
retval = tty->ops->open(tty, filp);
else
retval = -ENODEV;
filp->f_flags = saved_flags;
if (retval) {
tty_debug_hangup(tty, "open error %d, releasing\n", retval);
tty_unlock(tty); /* need to call tty_release without BTM */
tty_release(inode, filp);
if (retval != -ERESTARTSYS)
return retval;
if (signal_pending(current))
return retval;
schedule();
/*
* Need to reset f_op in case a hangup happened.
*/
if (tty_hung_up_p(filp))
filp->f_op = &tty_fops;
goto retry_open;
}
clear_bit(TTY_HUPPED, &tty->flags);
read_lock(&tasklist_lock);
spin_lock_irq(&current->sighand->siglock);
noctty = (filp->f_flags & O_NOCTTY) ||
device == MKDEV(TTY_MAJOR, 0) ||
device == MKDEV(TTYAUX_MAJOR, 1) ||
(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
tty->session == NULL) {
/*
* Don't let a process that only has write access to the tty
* obtain the privileges associated with having a tty as
* controlling terminal (being able to reopen it with full
* access through /dev/tty, being able to perform pushback).
* Many distributions set the group of all ttys to "tty" and
* grant write-only access to all terminals for setgid tty
* binaries, which should not imply full privileges on all ttys.
*
* This could theoretically break old code that performs open()
* on a write-only file descriptor. In that case, it might be
* necessary to also permit this if
* inode_permission(inode, MAY_READ) == 0.
*/
if (filp->f_mode & FMODE_READ)
__proc_set_tty(tty);
}
spin_unlock_irq(&current->sighand->siglock);
read_unlock(&tasklist_lock);
tty_unlock(tty);
return 0;
}
/**
* tty_poll - check tty status
* @filp: file being polled
* @wait: poll wait structures to update
*
* Call the line discipline polling method to obtain the poll
* status of the device.
*
* Locking: locks called line discipline but ldisc poll method
* may be re-entered freely by other callers.
*/
static unsigned int tty_poll(struct file *filp, poll_table *wait)
{
struct tty_struct *tty = file_tty(filp);
struct tty_ldisc *ld;
int ret = 0;
if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
return 0;
ld = tty_ldisc_ref_wait(tty);
if (ld->ops->poll)
ret = ld->ops->poll(tty, filp, wait);
tty_ldisc_deref(ld);
return ret;
}
static int __tty_fasync(int fd, struct file *filp, int on)
{
struct tty_struct *tty = file_tty(filp);
struct tty_ldisc *ldisc;
unsigned long flags;
int retval = 0;
if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
goto out;
retval = fasync_helper(fd, filp, on, &tty->fasync);
if (retval <= 0)
goto out;
ldisc = tty_ldisc_ref(tty);
if (ldisc) {
if (ldisc->ops->fasync)
ldisc->ops->fasync(tty, on);
tty_ldisc_deref(ldisc);
}
if (on) {
enum pid_type type;
struct pid *pid;
spin_lock_irqsave(&tty->ctrl_lock, flags);
if (tty->pgrp) {
pid = tty->pgrp;
type = PIDTYPE_PGID;
} else {
pid = task_pid(current);
type = PIDTYPE_PID;
}
get_pid(pid);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
__f_setown(filp, pid, type, 0);
put_pid(pid);
retval = 0;
}
out:
return retval;
}
static int tty_fasync(int fd, struct file *filp, int on)
{
struct tty_struct *tty = file_tty(filp);
int retval;
tty_lock(tty);
retval = __tty_fasync(fd, filp, on);
tty_unlock(tty);
return retval;
}
/**
* tiocsti - fake input character
* @tty: tty to fake input into
* @p: pointer to character
*
* Fake input to a tty device. Does the necessary locking and
* input management.
*
* FIXME: does not honour flow control ??
*
* Locking:
* Called functions take tty_ldiscs_lock
* current->signal->tty check is safe without locks
*
* FIXME: may race normal receive processing
*/
static int tiocsti(struct tty_struct *tty, char __user *p)
{
char ch, mbz = 0;
struct tty_ldisc *ld;
if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
return -EPERM;
if (get_user(ch, p))
return -EFAULT;
tty_audit_tiocsti(tty, ch);
ld = tty_ldisc_ref_wait(tty);
ld->ops->receive_buf(tty, &ch, &mbz, 1);
tty_ldisc_deref(ld);
return 0;
}
/**
* tiocgwinsz - implement window query ioctl
* @tty; tty
* @arg: user buffer for result
*
* Copies the kernel idea of the window size into the user buffer.
*
* Locking: tty->winsize_mutex is taken to ensure the winsize data
* is consistent.
*/
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
{
int err;
mutex_lock(&tty->winsize_mutex);
err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
mutex_unlock(&tty->winsize_mutex);
return err ? -EFAULT: 0;
}
/**
* tty_do_resize - resize event
* @tty: tty being resized
* @rows: rows (character)
* @cols: cols (character)
*
* Update the termios variables and send the necessary signals to
* peform a terminal resize correctly
*/
int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
{
struct pid *pgrp;
/* Lock the tty */
mutex_lock(&tty->winsize_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done;
/* Signal the foreground process group */
pgrp = tty_get_pgrp(tty);
if (pgrp)
kill_pgrp(pgrp, SIGWINCH, 1);
put_pid(pgrp);
tty->winsize = *ws;
done:
mutex_unlock(&tty->winsize_mutex);
return 0;
}
EXPORT_SYMBOL(tty_do_resize);
/**
* tiocswinsz - implement window size set ioctl
* @tty; tty side of tty
* @arg: user buffer for result
*
* Copies the user idea of the window size to the kernel. Traditionally
* this is just advisory information but for the Linux console it
* actually has driver level meaning and triggers a VC resize.
*
* Locking:
* Driver dependent. The default do_resize method takes the
* tty termios mutex and ctrl_lock. The console takes its own lock
* then calls into the default method.
*/
static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
{
struct winsize tmp_ws;
if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
return -EFAULT;
if (tty->ops->resize)
return tty->ops->resize(tty, &tmp_ws);
else
return tty_do_resize(tty, &tmp_ws);
}
/**
* tioccons - allow admin to move logical console
* @file: the file to become console
*
* Allow the administrator to move the redirected console device
*
* Locking: uses redirect_lock to guard the redirect information
*/
static int tioccons(struct file *file)
{
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (file->f_op->write == redirected_tty_write) {
struct file *f;
spin_lock(&redirect_lock);
f = redirect;
redirect = NULL;
spin_unlock(&redirect_lock);
if (f)
fput(f);
return 0;
}
spin_lock(&redirect_lock);
if (redirect) {
spin_unlock(&redirect_lock);
return -EBUSY;
}
redirect = get_file(file);
spin_unlock(&redirect_lock);
return 0;
}
/**
* fionbio - non blocking ioctl
* @file: file to set blocking value
* @p: user parameter
*
* Historical tty interfaces had a blocking control ioctl before
* the generic functionality existed. This piece of history is preserved
* in the expected tty API of posix OS's.
*
* Locking: none, the open file handle ensures it won't go away.
*/
static int fionbio(struct file *file, int __user *p)
{
int nonblock;
if (get_user(nonblock, p))
return -EFAULT;
spin_lock(&file->f_lock);
if (nonblock)
file->f_flags |= O_NONBLOCK;
else
file->f_flags &= ~O_NONBLOCK;
spin_unlock(&file->f_lock);
return 0;
}
/**
* tiocsctty - set controlling tty
* @tty: tty structure
* @arg: user argument
*
* This ioctl is used to manage job control. It permits a session
* leader to set this tty as the controlling tty for the session.
*
* Locking:
* Takes tty_lock() to serialize proc_set_tty() for this tty
* Takes tasklist_lock internally to walk sessions
* Takes ->siglock() when updating signal->tty
*/
static int tiocsctty(struct tty_struct *tty, struct file *file, int arg)
{
int ret = 0;
tty_lock(tty);
read_lock(&tasklist_lock);
if (current->signal->leader && (task_session(current) == tty->session))
goto unlock;
/*
* The process must be a session leader and
* not have a controlling tty already.
*/
if (!current->signal->leader || current->signal->tty) {
ret = -EPERM;
goto unlock;
}
if (tty->session) {
/*
* This tty is already the controlling
* tty for another session group!
*/
if (arg == 1 && capable(CAP_SYS_ADMIN)) {
/*
* Steal it away
*/
session_clear_tty(tty->session);
} else {
ret = -EPERM;
goto unlock;
}
}
/* See the comment in tty_open(). */
if ((file->f_mode & FMODE_READ) == 0 && !capable(CAP_SYS_ADMIN)) {
ret = -EPERM;
goto unlock;
}
proc_set_tty(tty);
unlock:
read_unlock(&tasklist_lock);
tty_unlock(tty);
return ret;
}
/**
* tty_get_pgrp - return a ref counted pgrp pid
* @tty: tty to read
*
* Returns a refcounted instance of the pid struct for the process
* group controlling the tty.
*/
struct pid *tty_get_pgrp(struct tty_struct *tty)
{
unsigned long flags;
struct pid *pgrp;
spin_lock_irqsave(&tty->ctrl_lock, flags);
pgrp = get_pid(tty->pgrp);
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
return pgrp;
}
EXPORT_SYMBOL_GPL(tty_get_pgrp);
/*
* This checks not only the pgrp, but falls back on the pid if no
* satisfactory pgrp is found. I dunno - gdb doesn't work correctly
* without this...
*
* The caller must hold rcu lock or the tasklist lock.
*/
static struct pid *session_of_pgrp(struct pid *pgrp)
{
struct task_struct *p;
struct pid *sid = NULL;
p = pid_task(pgrp, PIDTYPE_PGID);
if (p == NULL)
p = pid_task(pgrp, PIDTYPE_PID);
if (p != NULL)
sid = task_session(p);
return sid;
}
/**
* tiocgpgrp - get process group
* @tty: tty passed by user
* @real_tty: tty side of the tty passed by the user if a pty else the tty
* @p: returned pid
*
* Obtain the process group of the tty. If there is no process group
* return an error.
*
* Locking: none. Reference to current->signal->tty is safe.
*/
static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
struct pid *pid;
int ret;
/*
* (tty == real_tty) is a cheap way of
* testing if the tty is NOT a master pty.
*/
if (tty == real_tty && current->signal->tty != real_tty)
return -ENOTTY;
pid = tty_get_pgrp(real_tty);
ret = put_user(pid_vnr(pid), p);
put_pid(pid);
return ret;
}
/**
* tiocspgrp - attempt to set process group
* @tty: tty passed by user
* @real_tty: tty side device matching tty passed by user
* @p: pid pointer
*
* Set the process group of the tty to the session passed. Only
* permitted where the tty session is our session.
*
* Locking: RCU, ctrl lock
*/
static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
struct pid *pgrp;
pid_t pgrp_nr;
int retval = tty_check_change(real_tty);
if (retval == -EIO)
return -ENOTTY;
if (retval)
return retval;
if (!current->signal->tty ||
(current->signal->tty != real_tty) ||
(real_tty->session != task_session(current)))
return -ENOTTY;
if (get_user(pgrp_nr, p))
return -EFAULT;
if (pgrp_nr < 0)
return -EINVAL;
rcu_read_lock();
pgrp = find_vpid(pgrp_nr);
retval = -ESRCH;
if (!pgrp)
goto out_unlock;
retval = -EPERM;
if (session_of_pgrp(pgrp) != task_session(current))
goto out_unlock;
retval = 0;
spin_lock_irq(&tty->ctrl_lock);
put_pid(real_tty->pgrp);
real_tty->pgrp = get_pid(pgrp);
spin_unlock_irq(&tty->ctrl_lock);
out_unlock:
rcu_read_unlock();
return retval;
}
/**
* tiocgsid - get session id
* @tty: tty passed by user
* @real_tty: tty side of the tty passed by the user if a pty else the tty
* @p: pointer to returned session id
*
* Obtain the session id of the tty. If there is no session
* return an error.
*
* Locking: none. Reference to current->signal->tty is safe.
*/
static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p)
{
/*
* (tty == real_tty) is a cheap way of
* testing if the tty is NOT a master pty.
*/
if (tty == real_tty && current->signal->tty != real_tty)
return -ENOTTY;
if (!real_tty->session)
return -ENOTTY;
return put_user(pid_vnr(real_tty->session), p);
}
/**
* tiocsetd - set line discipline
* @tty: tty device
* @p: pointer to user data
*
* Set the line discipline according to user request.
*
* Locking: see tty_set_ldisc, this function is just a helper
*/
static int tiocsetd(struct tty_struct *tty, int __user *p)
{
int ldisc;
int ret;
if (get_user(ldisc, p))
return -EFAULT;
ret = tty_set_ldisc(tty, ldisc);
return ret;
}
/**
* tiocgetd - get line discipline
* @tty: tty device
* @p: pointer to user data
*
* Retrieves the line discipline id directly from the ldisc.
*
* Locking: waits for ldisc reference (in case the line discipline
* is changing or the tty is being hungup)
*/
static int tiocgetd(struct tty_struct *tty, int __user *p)
{
struct tty_ldisc *ld;
int ret;
ld = tty_ldisc_ref_wait(tty);
ret = put_user(ld->ops->num, p);
tty_ldisc_deref(ld);
return ret;
}
/**
* send_break - performed time break
* @tty: device to break on
* @duration: timeout in mS
*
* Perform a timed break on hardware that lacks its own driver level
* timed break functionality.
*
* Locking:
* atomic_write_lock serializes
*
*/
static int send_break(struct tty_struct *tty, unsigned int duration)
{
int retval;
if (tty->ops->break_ctl == NULL)
return 0;
if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
retval = tty->ops->break_ctl(tty, duration);
else {
/* Do the work ourselves */
if (tty_write_lock(tty, 0) < 0)
return -EINTR;
retval = tty->ops->break_ctl(tty, -1);
if (retval)
goto out;
if (!signal_pending(current))
msleep_interruptible(duration);
retval = tty->ops->break_ctl(tty, 0);
out:
tty_write_unlock(tty);
if (signal_pending(current))
retval = -EINTR;
}
return retval;
}
/**
* tty_tiocmget - get modem status
* @tty: tty device
* @file: user file pointer
* @p: pointer to result
*
* Obtain the modem status bits from the tty driver if the feature
* is supported. Return -EINVAL if it is not available.
*
* Locking: none (up to the driver)
*/
static int tty_tiocmget(struct tty_struct *tty, int __user *p)
{
int retval = -EINVAL;
if (tty->ops->tiocmget) {
retval = tty->ops->tiocmget(tty);
if (retval >= 0)
retval = put_user(retval, p);
}
return retval;
}
/**
* tty_tiocmset - set modem status
* @tty: tty device
* @cmd: command - clear bits, set bits or set all
* @p: pointer to desired bits
*
* Set the modem status bits from the tty driver if the feature
* is supported. Return -EINVAL if it is not available.
*
* Locking: none (up to the driver)
*/
static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
unsigned __user *p)
{
int retval;
unsigned int set, clear, val;
if (tty->ops->tiocmset == NULL)
return -EINVAL;
retval = get_user(val, p);
if (retval)
return retval;
set = clear = 0;
switch (cmd) {
case TIOCMBIS:
set = val;
break;
case TIOCMBIC:
clear = val;
break;
case TIOCMSET:
set = val;
clear = ~val;
break;
}
set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
return tty->ops->tiocmset(tty, set, clear);
}
static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
{
int retval = -EINVAL;
struct serial_icounter_struct icount;
memset(&icount, 0, sizeof(icount));
if (tty->ops->get_icount)
retval = tty->ops->get_icount(tty, &icount);
if (retval != 0)
return retval;
if (copy_to_user(arg, &icount, sizeof(icount)))
return -EFAULT;
return 0;
}
static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
{
static DEFINE_RATELIMIT_STATE(depr_flags,
DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
char comm[TASK_COMM_LEN];
int flags;
if (get_user(flags, &ss->flags))
return;
flags &= ASYNC_DEPRECATED;
if (flags && __ratelimit(&depr_flags))
pr_warning("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
__func__, get_task_comm(comm, current), flags);
}
/*
* if pty, return the slave side (real_tty)
* otherwise, return self
*/
static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
{
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
tty = tty->link;
return tty;
}
/*
* Split this up, as gcc can choke on it otherwise..
*/
long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct tty_struct *tty = file_tty(file);
struct tty_struct *real_tty;
void __user *p = (void __user *)arg;
int retval;
struct tty_ldisc *ld;
if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
return -EINVAL;
real_tty = tty_pair_get_tty(tty);
/*
* Factor out some common prep work
*/
switch (cmd) {
case TIOCSETD:
case TIOCSBRK:
case TIOCCBRK:
case TCSBRK:
case TCSBRKP:
retval = tty_check_change(tty);
if (retval)
return retval;
if (cmd != TIOCCBRK) {
tty_wait_until_sent(tty, 0);
if (signal_pending(current))
return -EINTR;
}
break;
}
/*
* Now do the stuff.
*/
switch (cmd) {
case TIOCSTI:
return tiocsti(tty, p);
case TIOCGWINSZ:
return tiocgwinsz(real_tty, p);
case TIOCSWINSZ:
return tiocswinsz(real_tty, p);
case TIOCCONS:
return real_tty != tty ? -EINVAL : tioccons(file);
case FIONBIO:
return fionbio(file, p);
case TIOCEXCL:
set_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCNXCL:
clear_bit(TTY_EXCLUSIVE, &tty->flags);
return 0;
case TIOCGEXCL:
{
int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
return put_user(excl, (int __user *)p);
}
case TIOCNOTTY:
if (current->signal->tty != tty)
return -ENOTTY;
no_tty();
return 0;
case TIOCSCTTY:
return tiocsctty(real_tty, file, arg);
case TIOCGPGRP:
return tiocgpgrp(tty, real_tty, p);
case TIOCSPGRP:
return tiocspgrp(tty, real_tty, p);
case TIOCGSID:
return tiocgsid(tty, real_tty, p);
case TIOCGETD:
return tiocgetd(tty, p);
case TIOCSETD:
return tiocsetd(tty, p);
case TIOCVHANGUP:
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
tty_vhangup(tty);
return 0;
case TIOCGDEV:
{
unsigned int ret = new_encode_dev(tty_devnum(real_tty));
return put_user(ret, (unsigned int __user *)p);
}
/*
* Break handling
*/
case TIOCSBRK: /* Turn break on, unconditionally */
if (tty->ops->break_ctl)
return tty->ops->break_ctl(tty, -1);
return 0;
case TIOCCBRK: /* Turn break off, unconditionally */
if (tty->ops->break_ctl)
return tty->ops->break_ctl(tty, 0);
return 0;
case TCSBRK: /* SVID version: non-zero arg --> no break */
/* non-zero arg means wait for all output data
* to be sent (performed above) but don't send break.
* This is used by the tcdrain() termios function.
*/
if (!arg)
return send_break(tty, 250);
return 0;
case TCSBRKP: /* support for POSIX tcsendbreak() */
return send_break(tty, arg ? arg*100 : 250);
case TIOCMGET:
return tty_tiocmget(tty, p);
case TIOCMSET:
case TIOCMBIC:
case TIOCMBIS:
return tty_tiocmset(tty, cmd, p);
case TIOCGICOUNT:
retval = tty_tiocgicount(tty, p);
/* For the moment allow fall through to the old method */
if (retval != -EINVAL)
return retval;
break;
case TCFLSH:
switch (arg) {
case TCIFLUSH:
case TCIOFLUSH:
/* flush tty buffer and allow ldisc to process ioctl */
tty_buffer_flush(tty, NULL);
break;
}
break;
case TIOCSSERIAL:
tty_warn_deprecated_flags(p);
break;
}
if (tty->ops->ioctl) {
retval = tty->ops->ioctl(tty, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
retval = -EINVAL;
if (ld->ops->ioctl) {
retval = ld->ops->ioctl(tty, file, cmd, arg);
if (retval == -ENOIOCTLCMD)
retval = -ENOTTY;
}
tty_ldisc_deref(ld);
return retval;
}
#ifdef CONFIG_COMPAT
static long tty_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
int retval = -ENOIOCTLCMD;
if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
return -EINVAL;
if (tty->ops->compat_ioctl) {
retval = tty->ops->compat_ioctl(tty, cmd, arg);
if (retval != -ENOIOCTLCMD)
return retval;
}
ld = tty_ldisc_ref_wait(tty);
if (ld->ops->compat_ioctl)
retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
else
retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
tty_ldisc_deref(ld);
return retval;
}
#endif
static int this_tty(const void *t, struct file *file, unsigned fd)
{
if (likely(file->f_op->read != tty_read))
return 0;
return file_tty(file) != t ? 0 : fd + 1;
}
/*
* This implements the "Secure Attention Key" --- the idea is to
* prevent trojan horses by killing all processes associated with this
* tty when the user hits the "Secure Attention Key". Required for
* super-paranoid applications --- see the Orange Book for more details.
*
* This code could be nicer; ideally it should send a HUP, wait a few
* seconds, then send a INT, and then a KILL signal. But you then
* have to coordinate with the init process, since all processes associated
* with the current tty must be dead before the new getty is allowed
* to spawn.
*
* Now, if it would be correct ;-/ The current code has a nasty hole -
* it doesn't catch files in flight. We may send the descriptor to ourselves
* via AF_UNIX socket, close it and later fetch from socket. FIXME.
*
* Nasty bug: do_SAK is being called in interrupt context. This can
* deadlock. We punt it up to process context. AKPM - 16Mar2001
*/
void __do_SAK(struct tty_struct *tty)
{
#ifdef TTY_SOFT_SAK
tty_hangup(tty);
#else
struct task_struct *g, *p;
struct pid *session;
int i;
if (!tty)
return;
session = tty->session;
tty_ldisc_flush(tty);
tty_driver_flush_buffer(tty);
read_lock(&tasklist_lock);
/* Kill the entire session */
do_each_pid_task(session, PIDTYPE_SID, p) {
tty_notice(tty, "SAK: killed process %d (%s): by session\n",
task_pid_nr(p), p->comm);
send_sig(SIGKILL, p, 1);
} while_each_pid_task(session, PIDTYPE_SID, p);
/* Now kill any processes that happen to have the tty open */
do_each_thread(g, p) {
if (p->signal->tty == tty) {
tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
task_pid_nr(p), p->comm);
send_sig(SIGKILL, p, 1);
continue;
}
task_lock(p);
i = iterate_fd(p->files, 0, this_tty, tty);
if (i != 0) {
tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
task_pid_nr(p), p->comm, i - 1);
force_sig(SIGKILL, p);
}
task_unlock(p);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
#endif
}
static void do_SAK_work(struct work_struct *work)
{
struct tty_struct *tty =
container_of(work, struct tty_struct, SAK_work);
__do_SAK(tty);
}
/*
* The tq handling here is a little racy - tty->SAK_work may already be queued.
* Fortunately we don't need to worry, because if ->SAK_work is already queued,
* the values which we write to it will be identical to the values which it
* already has. --akpm
*/
void do_SAK(struct tty_struct *tty)
{
if (!tty)
return;
schedule_work(&tty->SAK_work);
}
EXPORT_SYMBOL(do_SAK);
static int dev_match_devt(struct device *dev, const void *data)
{
const dev_t *devt = data;
return dev->devt == *devt;
}
/* Must put_device() after it's unused! */
static struct device *tty_get_device(struct tty_struct *tty)
{
dev_t devt = tty_devnum(tty);
return class_find_device(tty_class, NULL, &devt, dev_match_devt);
}
/**
* alloc_tty_struct
*
* This subroutine allocates and initializes a tty structure.
*
* Locking: none - tty in question is not exposed at this point
*/
struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
{
struct tty_struct *tty;
tty = kzalloc(sizeof(*tty), GFP_KERNEL);
if (!tty)
return NULL;
kref_init(&tty->kref);
tty->magic = TTY_MAGIC;
tty_ldisc_init(tty);
tty->session = NULL;
tty->pgrp = NULL;
mutex_init(&tty->legacy_mutex);
mutex_init(&tty->throttle_mutex);
init_rwsem(&tty->termios_rwsem);
mutex_init(&tty->winsize_mutex);
init_ldsem(&tty->ldisc_sem);
init_waitqueue_head(&tty->write_wait);
init_waitqueue_head(&tty->read_wait);
INIT_WORK(&tty->hangup_work, do_tty_hangup);
mutex_init(&tty->atomic_write_lock);
spin_lock_init(&tty->ctrl_lock);
spin_lock_init(&tty->flow_lock);
INIT_LIST_HEAD(&tty->tty_files);
INIT_WORK(&tty->SAK_work, do_SAK_work);
tty->driver = driver;
tty->ops = driver->ops;
tty->index = idx;
tty_line_name(driver, idx, tty->name);
tty->dev = tty_get_device(tty);
return tty;
}
/**
* tty_put_char - write one character to a tty
* @tty: tty
* @ch: character
*
* Write one byte to the tty using the provided put_char method
* if present. Returns the number of characters successfully output.
*
* Note: the specific put_char operation in the driver layer may go
* away soon. Don't call it directly, use this method
*/
int tty_put_char(struct tty_struct *tty, unsigned char ch)
{
if (tty->ops->put_char)
return tty->ops->put_char(tty, ch);
return tty->ops->write(tty, &ch, 1);
}
EXPORT_SYMBOL_GPL(tty_put_char);
struct class *tty_class;
static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
unsigned int index, unsigned int count)
{
int err;
/* init here, since reused cdevs cause crashes */
driver->cdevs[index] = cdev_alloc();
if (!driver->cdevs[index])
return -ENOMEM;
driver->cdevs[index]->ops = &tty_fops;
driver->cdevs[index]->owner = driver->owner;
err = cdev_add(driver->cdevs[index], dev, count);
if (err)
kobject_put(&driver->cdevs[index]->kobj);
return err;
}
/**
* tty_register_device - register a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
* @device: a struct device that is associated with this tty device.
* This field is optional, if there is no known struct device
* for this tty device it can be set to NULL safely.
*
* Returns a pointer to the struct device for this tty device
* (or ERR_PTR(-EFOO) on error).
*
* This call is required to be made to register an individual tty device
* if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
* that bit is not set, this function should not be called by a tty
* driver.
*
* Locking: ??
*/
struct device *tty_register_device(struct tty_driver *driver, unsigned index,
struct device *device)
{
return tty_register_device_attr(driver, index, device, NULL, NULL);
}
EXPORT_SYMBOL(tty_register_device);
static void tty_device_create_release(struct device *dev)
{
dev_dbg(dev, "releasing...\n");
kfree(dev);
}
/**
* tty_register_device_attr - register a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
* @device: a struct device that is associated with this tty device.
* This field is optional, if there is no known struct device
* for this tty device it can be set to NULL safely.
* @drvdata: Driver data to be set to device.
* @attr_grp: Attribute group to be set on device.
*
* Returns a pointer to the struct device for this tty device
* (or ERR_PTR(-EFOO) on error).
*
* This call is required to be made to register an individual tty device
* if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
* that bit is not set, this function should not be called by a tty
* driver.
*
* Locking: ??
*/
struct device *tty_register_device_attr(struct tty_driver *driver,
unsigned index, struct device *device,
void *drvdata,
const struct attribute_group **attr_grp)
{
char name[64];
dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
struct device *dev = NULL;
int retval = -ENODEV;
bool cdev = false;
if (index >= driver->num) {
pr_err("%s: Attempt to register invalid tty line number (%d)\n",
driver->name, index);
return ERR_PTR(-EINVAL);
}
if (driver->type == TTY_DRIVER_TYPE_PTY)
pty_line_name(driver, index, name);
else
tty_line_name(driver, index, name);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
retval = tty_cdev_add(driver, devt, index, 1);
if (retval)
goto error;
cdev = true;
}
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (!dev) {
retval = -ENOMEM;
goto error;
}
dev->devt = devt;
dev->class = tty_class;
dev->parent = device;
dev->release = tty_device_create_release;
dev_set_name(dev, "%s", name);
dev->groups = attr_grp;
dev_set_drvdata(dev, drvdata);
retval = device_register(dev);
if (retval)
goto error;
return dev;
error:
put_device(dev);
if (cdev) {
cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(tty_register_device_attr);
/**
* tty_unregister_device - unregister a tty device
* @driver: the tty driver that describes the tty device
* @index: the index in the tty driver for this tty device
*
* If a tty device is registered with a call to tty_register_device() then
* this function must be called when the tty device is gone.
*
* Locking: ??
*/
void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
device_destroy(tty_class,
MKDEV(driver->major, driver->minor_start) + index);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
cdev_del(driver->cdevs[index]);
driver->cdevs[index] = NULL;
}
}
EXPORT_SYMBOL(tty_unregister_device);
/**
* __tty_alloc_driver -- allocate tty driver
* @lines: count of lines this driver can handle at most
* @owner: module which is repsonsible for this driver
* @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
*
* This should not be called directly, some of the provided macros should be
* used instead. Use IS_ERR and friends on @retval.
*/
struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
unsigned long flags)
{
struct tty_driver *driver;
unsigned int cdevs = 1;
int err;
if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
return ERR_PTR(-EINVAL);
driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
if (!driver)
return ERR_PTR(-ENOMEM);
kref_init(&driver->kref);
driver->magic = TTY_DRIVER_MAGIC;
driver->num = lines;
driver->owner = owner;
driver->flags = flags;
if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
GFP_KERNEL);
driver->termios = kcalloc(lines, sizeof(*driver->termios),
GFP_KERNEL);
if (!driver->ttys || !driver->termios) {
err = -ENOMEM;
goto err_free_all;
}
}
if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
driver->ports = kcalloc(lines, sizeof(*driver->ports),
GFP_KERNEL);
if (!driver->ports) {
err = -ENOMEM;
goto err_free_all;
}
cdevs = lines;
}
driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
if (!driver->cdevs) {
err = -ENOMEM;
goto err_free_all;
}
return driver;
err_free_all:
kfree(driver->ports);
kfree(driver->ttys);
kfree(driver->termios);
kfree(driver->cdevs);
kfree(driver);
return ERR_PTR(err);
}
EXPORT_SYMBOL(__tty_alloc_driver);
static void destruct_tty_driver(struct kref *kref)
{
struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
int i;
struct ktermios *tp;
if (driver->flags & TTY_DRIVER_INSTALLED) {
/*
* Free the termios and termios_locked structures because
* we don't want to get memory leaks when modular tty
* drivers are removed from the kernel.
*/
for (i = 0; i < driver->num; i++) {
tp = driver->termios[i];
if (tp) {
driver->termios[i] = NULL;
kfree(tp);
}
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
tty_unregister_device(driver, i);
}
proc_tty_unregister_driver(driver);
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
cdev_del(driver->cdevs[0]);
}
kfree(driver->cdevs);
kfree(driver->ports);
kfree(driver->termios);
kfree(driver->ttys);
kfree(driver);
}
void tty_driver_kref_put(struct tty_driver *driver)
{
kref_put(&driver->kref, destruct_tty_driver);
}
EXPORT_SYMBOL(tty_driver_kref_put);
void tty_set_operations(struct tty_driver *driver,
const struct tty_operations *op)
{
driver->ops = op;
};
EXPORT_SYMBOL(tty_set_operations);
void put_tty_driver(struct tty_driver *d)
{
tty_driver_kref_put(d);
}
EXPORT_SYMBOL(put_tty_driver);
/*
* Called by a tty driver to register itself.
*/
int tty_register_driver(struct tty_driver *driver)
{
int error;
int i;
dev_t dev;
struct device *d;
if (!driver->major) {
error = alloc_chrdev_region(&dev, driver->minor_start,
driver->num, driver->name);
if (!error) {
driver->major = MAJOR(dev);
driver->minor_start = MINOR(dev);
}
} else {
dev = MKDEV(driver->major, driver->minor_start);
error = register_chrdev_region(dev, driver->num, driver->name);
}
if (error < 0)
goto err;
if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
error = tty_cdev_add(driver, dev, 0, driver->num);
if (error)
goto err_unreg_char;
}
mutex_lock(&tty_mutex);
list_add(&driver->tty_drivers, &tty_drivers);
mutex_unlock(&tty_mutex);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
for (i = 0; i < driver->num; i++) {
d = tty_register_device(driver, i, NULL);
if (IS_ERR(d)) {
error = PTR_ERR(d);
goto err_unreg_devs;
}
}
}
proc_tty_register_driver(driver);
driver->flags |= TTY_DRIVER_INSTALLED;
return 0;
err_unreg_devs:
for (i--; i >= 0; i--)
tty_unregister_device(driver, i);
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
err_unreg_char:
unregister_chrdev_region(dev, driver->num);
err:
return error;
}
EXPORT_SYMBOL(tty_register_driver);
/*
* Called by a tty driver to unregister itself.
*/
int tty_unregister_driver(struct tty_driver *driver)
{
#if 0
/* FIXME */
if (driver->refcount)
return -EBUSY;
#endif
unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
driver->num);
mutex_lock(&tty_mutex);
list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
return 0;
}
EXPORT_SYMBOL(tty_unregister_driver);
dev_t tty_devnum(struct tty_struct *tty)
{
return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
}
EXPORT_SYMBOL(tty_devnum);
void tty_default_fops(struct file_operations *fops)
{
*fops = tty_fops;
}
/*
* Initialize the console device. This is called *early*, so
* we can't necessarily depend on lots of kernel help here.
* Just do some early initializations, and do the complex setup
* later.
*/
void __init console_init(void)
{
initcall_t *call;
/* Setup the default TTY line discipline. */
tty_ldisc_begin();
/*
* set up the console device so that later boot sequences can
* inform about problems etc..
*/
call = __con_initcall_start;
while (call < __con_initcall_end) {
(*call)();
call++;
}
}
static char *tty_devnode(struct device *dev, umode_t *mode)
{
if (!mode)
return NULL;
if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
dev->devt == MKDEV(TTYAUX_MAJOR, 2))
*mode = 0666;
return NULL;
}
static int __init tty_class_init(void)
{
tty_class = class_create(THIS_MODULE, "tty");
if (IS_ERR(tty_class))
return PTR_ERR(tty_class);
tty_class->devnode = tty_devnode;
return 0;
}
postcore_initcall(tty_class_init);
/* 3/2004 jmc: why do these devices exist? */
static struct cdev tty_cdev, console_cdev;
static ssize_t show_cons_active(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct console *cs[16];
int i = 0;
struct console *c;
ssize_t count = 0;
console_lock();
for_each_console(c) {
if (!c->device)
continue;
if (!c->write)
continue;
if ((c->flags & CON_ENABLED) == 0)
continue;
cs[i++] = c;
if (i >= ARRAY_SIZE(cs))
break;
}
while (i--) {
int index = cs[i]->index;
struct tty_driver *drv = cs[i]->device(cs[i], &index);
/* don't resolve tty0 as some programs depend on it */
if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
count += tty_line_name(drv, index, buf + count);
else
count += sprintf(buf + count, "%s%d",
cs[i]->name, cs[i]->index);
count += sprintf(buf + count, "%c", i ? ' ':'\n');
}
console_unlock();
return count;
}
static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
static struct attribute *cons_dev_attrs[] = {
&dev_attr_active.attr,
NULL
};
ATTRIBUTE_GROUPS(cons_dev);
static struct device *consdev;
void console_sysfs_notify(void)
{
if (consdev)
sysfs_notify(&consdev->kobj, NULL, "active");
}
/*
* Ok, now we can initialize the rest of the tty devices and can count
* on memory allocations, interrupts etc..
*/
int __init tty_init(void)
{
cdev_init(&tty_cdev, &tty_fops);
if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
panic("Couldn't register /dev/tty driver\n");
device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
cdev_init(&console_cdev, &console_fops);
if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
panic("Couldn't register /dev/console driver\n");
consdev = device_create_with_groups(tty_class, NULL,
MKDEV(TTYAUX_MAJOR, 1), NULL,
cons_dev_groups, "console");
if (IS_ERR(consdev))
consdev = NULL;
#ifdef CONFIG_VT
vty_init(&console_fops);
#endif
return 0;
}
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