/*
* This function is called at module load time, and creates the
* directory in debugfs and the two files.
*/
static int __init nullderef_init(void)
{
/* Create the directory our files will live in. */
nullderef_root = debugfs_create_dir("nullderef", NULL);
if (!nullderef_root) {
printk(KERN_ERR "nullderef: creating root dir failed\n");
return -ENODEV;
}
/*
* Create the null_read and null_call files. Use the fops
* structs defined above so that the kernel knows how to
* handle writes to them, and set the permissions to be
* writable by anyone.
*/
read_de = debugfs_create_file("null_read", 0222, nullderef_root,
NULL, &null_read_fops);
call_de = debugfs_create_file("null_call", 0222, nullderef_root,
NULL, &null_call_fops);
if (!read_de || !call_de)
goto out_err;
return 0;
out_err:
cleanup_debugfs();
return -ENODEV;
}
/* module loading callback */
static int
kernwrite_init(void)
{
/* initialize the data pointer to `ops' */
ops_ptr = &ops;
/* create the kernwrite directory in debugfs */
kernwrite_root = debugfs_create_dir("kernwrite", NULL);
/* failed */
if (kernwrite_root == NULL) {
/* verbose */
printk(KERN_ERR "kernwrite: creating root dir failed\n");
return -ENODEV;
}
/* create the files with the appropriate `fops' struct and perms */
over_func_ptr = debugfs_create_file("over_func_ptr",
0222,
kernwrite_root,
NULL,
&over_func_fops);
over_data_ptr = debugfs_create_file("over_data_ptr",
0222,
kernwrite_root,
NULL,
&over_data_fops);
invoke_func_ptr = debugfs_create_file("invoke_func",
0222,
kernwrite_root,
NULL,
&invoke_func_fops);
/* error handling */
if (over_func_ptr == NULL ||
over_data_ptr == NULL ||
invoke_func_ptr == NULL)
goto out_err;
/* return with success */
return 0;
out_err: /* cleanup */
printk(KERN_ERR "kernwrite: creating files in root dir failed\n");
cleanup_debugfs();
/* return with failure */
return -ENODEV;
}
/*
* This function is called on module unload, and cleans up our files.
*/
static void __exit nullderef_exit(void)
{
cleanup_debugfs();
}
/* module unloading callback */
static void
kernwrite_exit(void)
{
cleanup_debugfs();
}
