From d595cdf771c49137d3063b1396bd548166d3f346 Mon Sep 17 00:00:00 2001
From: rick <rick@gnous.eu>
Date: Sun, 4 Feb 2024 15:41:23 +0100
Subject: [PATCH] add task 12

---
 README.md        |  15 +++++++
 task_12/Makefile |   9 ++++
 task_12/list.c   | 114 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 138 insertions(+)
 create mode 100644 task_12/Makefile
 create mode 100644 task_12/list.c

diff --git a/README.md b/README.md
index 7d2c047..501aa39 100644
--- a/README.md
+++ b/README.md
@@ -287,6 +287,21 @@ ls -l /sys/eudyptula/
    `kobject`](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/samples/kobject)
  * [Chapitre 14, Linux Device Drivers, 3rd Edition](https://lwn.net/Kernel/LDD3/)
 
+### Tache 12
+
+Il suffit de charger le menu et de lire les messages noyaux pour voir le bon
+fonctionnement. J'ai repris le `main` donné dans l'ennoncé sans le modifier
+plus que ça :
+
+```
+[1220142.976299] Coucou le gens !!!!
+[1220142.976340] id 3 = Dave
+[1220142.976346] id 42 not found
+[1220148.124624] Tschuss !!!
+```
+
+ * [Chapitre 11, Linux Device Drivers, 3rd Edition](https://lwn.net/Kernel/LDD3/)
+
 ## Informations diverses
 
 Je liste dans cette section quelques informations que j'ai pu découvrir en
diff --git a/task_12/Makefile b/task_12/Makefile
new file mode 100644
index 0000000..98f3242
--- /dev/null
+++ b/task_12/Makefile
@@ -0,0 +1,9 @@
+obj-m += list.o
+
+PWD := $(CURDIR)
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
diff --git a/task_12/list.c b/task_12/list.c
new file mode 100644
index 0000000..b5fa8fa
--- /dev/null
+++ b/task_12/list.c
@@ -0,0 +1,114 @@
+// 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.");