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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
static int major_num;
static int busy;
static int cool_open(struct inode *inode, struct file *file) {
/* Check if we are already serving someone */
if (busy) {
return -EBUSY;
}
busy = 1;
return 0;
}
static int cool_release (struct inode *inode, struct file *file) {
busy = 0;
return 0;
}
static ssize_t cool_read (struct file *filp, char *buffer, size_t len, loff_t *offset) {
char str[12] = "hej med dig";
int i;
for (i = 0; i < len; i++) {
put_user(str[i % 12], buffer++);
}
return i;
}
static struct file_operations file_ops = {
.owner = THIS_MODULE,
.read = cool_read,
.open = cool_open,
.release = cool_release
};
static int __init jmod_init(void)
{
printk(KERN_INFO "COOL_MODULE: Registering cooldev\n");
major_num = register_chrdev(0, "cooldev", &file_ops);
if (major_num < 0) {
printk(KERN_ERR "COOL_MODULE: Could not register major\n");
return 1;
}
printk(KERN_INFO "COOL_MODULE: Got major %d\n", major_num);
return 0;
}
static void __exit jmod_exit(void)
{
printk(KERN_INFO "COOL_MODULE: Nou moe\n");
unregister_chrdev(major_num, "cooldev");
}
module_init( jmod_init );
module_exit( jmod_exit );
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