init

ass08/Makefile

@@ -0,0 +1,7 @@
+obj-m += main.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

ass08/main.c

@@ -0,0 +1,63 @@
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Louis Solofrizzo <louis@ne02ptzero.me>");
+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)