/usr/src/backfire-0.84-2/backfire.c is in backfire-dkms 0.87-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* backfire - send signal back to caller
*
* Copyright (C) 2007 Carsten Emde <C.Emde@osadl.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307,
* USA.
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/time.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#define BACKFIRE_MINOR MISC_DYNAMIC_MINOR
static DEFINE_SPINLOCK(backfire_state_lock);
static int backfire_open_cnt; /* #times opened */
static int backfire_open_mode; /* special open modes */
static struct timeval sendtime; /* when the most recent signal was sent */
#define BACKFIRE_WRITE 1 /* opened for writing (exclusive) */
#define BACKFIRE_EXCL 2 /* opened with O_EXCL */
/*
* These are the file operation function for user access to /dev/backfire
*/
static ssize_t
backfire_read(struct file *file, char *buf, size_t count, loff_t *ppos)
{
return snprintf(buf, count, "%d,%d\n", (int) sendtime.tv_sec,
(int) sendtime.tv_usec);
}
static ssize_t
backfire_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
int signo;
struct pid *pid;
if (sscanf(buf, "%d", &signo) >= 1) {
if (signo > 0 && signo < 32) {
pid = get_pid(task_pid(current));
do_gettimeofday(&sendtime);
kill_pid(pid, signo, 1);
} else
printk(KERN_ERR "Invalid signal no. %d\n", signo);
}
return strlen(buf);
}
static int
backfire_open(struct inode *inode, struct file *file)
{
spin_lock(&backfire_state_lock);
if ((backfire_open_cnt && (file->f_flags & O_EXCL)) ||
(backfire_open_mode & BACKFIRE_EXCL)) {
spin_unlock(&backfire_state_lock);
return -EBUSY;
}
if (file->f_flags & O_EXCL)
backfire_open_mode |= BACKFIRE_EXCL;
if (file->f_mode & 2)
backfire_open_mode |= BACKFIRE_WRITE;
backfire_open_cnt++;
spin_unlock(&backfire_state_lock);
return 0;
}
static int
backfire_release(struct inode *inode, struct file *file)
{
spin_lock(&backfire_state_lock);
backfire_open_cnt--;
if (backfire_open_cnt == 1 && backfire_open_mode & BACKFIRE_EXCL)
backfire_open_mode &= ~BACKFIRE_EXCL;
if (file->f_mode & 2)
backfire_open_mode &= ~BACKFIRE_WRITE;
spin_unlock(&backfire_state_lock);
return 0;
}
static struct file_operations backfire_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.open = backfire_open,
.read = backfire_read,
.write = backfire_write,
.release = backfire_release,
};
static struct miscdevice backfire_dev = {
BACKFIRE_MINOR,
"backfire",
&backfire_fops
};
static int __init backfire_init(void)
{
int ret;
ret = misc_register(&backfire_dev);
if (ret)
printk(KERN_ERR "backfire: can't register dynamic misc device\n");
else
printk(KERN_INFO "backfire driver misc device %d\n",
backfire_dev.minor);
return ret;
}
static void __exit backfire_exit(void)
{
misc_deregister(&backfire_dev);
}
module_init(backfire_init);
module_exit(backfire_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Carsten Emde <C.Emde@osadl.org>");
MODULE_DESCRIPTION("Send signal back to caller");
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