#include #include #include #include #include #include MODULE_LICENSE("GPL"); MODULE_AUTHOR("Louis Solofrizzo "); MODULE_DESCRIPTION("Useless module"); static ssize_t myfd_read(struct file *fp, char __user *user, size_t size, loff_t *offs); static ssize_t myfd_write(struct file *fp, const char __user *user, size_t size, loff_t *offs); static struct file_operations myfd_fops = { .owner = THIS_MODULE, .read = &myfd_read, .write = &myfd_write }; static struct miscdevice myfd_device = { .minor = MISC_DYNAMIC_MINOR, .name = "reverse", .fops = &myfd_fops }; char str[PAGE_SIZE]; static int __init myfd_init(void) { str[0] = 0; misc_register(&myfd_device); return 0; } static void __exit myfd_cleanup(void) { misc_deregister(&myfd_device); } ssize_t myfd_read(struct file *fp, char __user *buf, size_t size, loff_t *offs) { size_t str_len; char tmp[PAGE_SIZE + 1]; str_len = strlen(str); for (size_t i = 0; i != str_len; i++) tmp[i] = str[str_len - 1 - i]; return simple_read_from_buffer(buf, size, offs, tmp, str_len); } ssize_t myfd_write(struct file *fp, const char __user *buf, size_t size, loff_t *offs) { ssize_t res; res = simple_write_to_buffer(str, sizeof(str), offs, buf, PAGE_SIZE) + 1; str[size] = 0x0; return res; } module_init(myfd_init); module_exit(myfd_cleanup)