// SPDX-License-Identifier: GPL-2.0

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/string.h>

#define NAME_SIZE 20

struct identity {
	struct list_head list;
	char name[NAME_SIZE];
	int id;
	bool busy;
};

static struct list_head identity_list;

static int identity_create(char *name, int id)
{
	int ret = 0;
	struct identity *new = kmalloc(sizeof(*new), GFP_KERNEL);

	if (!new) {
		ret = -ENOMEM;
	} else {
		ssize_t name_len = strlen(name) + 1;

		if (name_len > NAME_SIZE) {
			ret = -EINVAL;
		} else {
			strscpy(new->name, name, name_len);
			new->id = id;
			new->busy = false;
			list_add_tail(&new->list, &identity_list);
		}
	}

	return ret;
}

static struct identity *identity_find(int id)
{
	struct identity *ret = NULL;
	struct identity *tmp = NULL;
	struct list_head *list = &identity_list;

	do {
		tmp = list_entry(list, struct identity, list);
		if (tmp->id == id)
			ret = tmp;
		else
			list = tmp->list.next;
	} while (list != &identity_list && !ret);

	return ret;
}

static void identity_destroy(int id)
{
	struct identity *tmp = identity_find(id);

	if (tmp) {
		list_del(&tmp->list);
		kfree(tmp);
	}
}

static int __init my_init(void)
{
	struct identity *temp;

	pr_info("Coucou le gens !!!!\n");
	INIT_LIST_HEAD(&identity_list);

	if (identity_create("Alice", 1))
		pr_info("Alice n'a pas été créée.");
	if (identity_create("Bob", 2))
		pr_info("Bob n'a pas été créée.");
	if (identity_create("Dave", 3))
		pr_info("Dave n'a pas été créée.");
	if (identity_create("Gena", 10))
		pr_info("Gena n'a pas été créée.");

	temp = identity_find(3);
	if (!temp)
		pr_info("id 3 not found\n");
  else
    pr_info("id 3 = %s\n", temp->name);

	temp = identity_find(42);
	if (!temp)
		pr_info("id 42 not found\n");

	identity_destroy(2);
	identity_destroy(1);
	identity_destroy(10);
	identity_destroy(42);
	identity_destroy(3);
	return 0;
}

static void __exit my_exit(void)
{
	pr_info("Tschuss !!!\n");
}

module_init(my_init);
module_exit(my_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("rick <rick@gnous.eu>");
MODULE_DESCRIPTION("Simple liste chainée.");