add assignement 00 to 08

07/id.c

@@ -0,0 +1,54 @@
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/debugfs.h>
+
+#define VALUE "tomoron"
+
+extern struct dentry *module_dir;
+ssize_t id_read(struct file *f, char __user *buf, size_t len, loff_t *off);
+ssize_t id_write(struct file *f, const char __user *buf, size_t len, loff_t *off);
+int init_id(void);
+
+
+static const struct file_operations fops = {
+	.owner = THIS_MODULE,
+	.read = id_read,
+	.write = id_write,
+};
+
+ssize_t id_read(struct file *f, char __user *buf, size_t len, loff_t *off)
+{
+	char msg[] = VALUE;
+	pr_info("someone read from the file\n");
+	return simple_read_from_buffer(buf, len, off, msg, sizeof(msg) - 1);
+}
+
+
+ssize_t id_write(struct file *f, const char __user *buf, size_t len, loff_t *off)
+{
+	char kbuf[64];
+	if (len > sizeof(kbuf) - 1)
+		return -EINVAL;
+	if (copy_from_user(kbuf, buf, len))
+		return -EINVAL;
+
+	kbuf[len] = '\0';
+
+	if (strcmp(kbuf, VALUE) == 0){
+		pr_info("someone wrote the right string\n");
+		return len;
+	}
+	pr_info("someone wrote the wrong string\n");
+	return -EINVAL;
+}
+
+int init_id(void)
+{
+	struct dentry *ret;
+	ret = debugfs_create_file("id", 0666, module_dir, NULL, &fops);
+	if(IS_ERR(ret))
+		return PTR_ERR(ret);
+	return 0;
+}