master commit

abcd.c

+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/cdev.h>
+#include <linux/types.h>
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Valentin Acevedo <valentin.acevedo-arroyo@etu.hesge.ch>");
+MODULE_DESCRIPTION("Alphabet buffer");
+MODULE_VERSION("1.0");
+
+// Buffer
+static int buff_size = 26;
+static char *buff;
+static dev_t major;
+
+struct mydevice {
+    char *string_data;
+    int int_data;
+    struct cdev mycdev;
+};
+
+static struct mydevice peripherique;
+
+static ssize_t custom_write(struct file *file, const char *buff, size_t len, loff_t *ppos) {
+    int real_buff_size = 0, write_buff_size = 0;
+
+    if(len <= buff_size - *ppos) {
+        real_buff_size = len;
+    } else {
+        real_buff_size = buff_size - *ppos;
+    }
+    if(real_buff_size) {
+        write_buff_size = copy_from_user((void*)buff + *ppos, buff, real_buff_size);
+    }
+    if(buff_size <*ppos + real_buff_size) {
+        *ppos = 0;
+    } else {
+        *ppos += real_buff_size;
+    }
+
+    return real_buff_size - write_buff_size;
+}
+
+static ssize_t custom_read(struct file *file, char *buff, size_t len, loff_t *ppos) {
+    int real_buff_size = 0, read_buff_size = 0;
+
+    if(buff_size - *ppos > len) {
+        real_buff_size = len;
+    } else {
+        real_buff_size = buff_size - *ppos;
+    }
+    if(real_buff_size) {
+        read_buff_size = copy_to_user(buff, buff + *ppos, real_buff_size);
+    }
+    if(buff_size < *ppos + real_buff_size) {
+        *ppos = 0;
+    } else {
+        *ppos += real_buff_size;
+    }
+
+    return real_buff_size - read_buff_size;
+}
+
+//Map used functions to custom created functions
+static struct file_operations custom_operations = {
+    read : custom_read,
+    write : custom_write
+};
+
+static int __init custom_init(void) {
+    int val;
+
+    buff = kmalloc(buff_size * sizeof(char), GFP_KERNEL);
+    memcpy(buff, "abcdefghijklmnopqrstuvwxyz", buff_size * sizeof(char));
+    val = alloc_chrdev_region(&major, 0, 1, "abcd");
+    if(val < 0) {
+        printk(KERN_WARNING "Module loading failure\n");
+        return val;
+    }
+    cdev_init(&(peripherique.mycdev), &custom_operations);
+    cdev_add(&(peripherique.mycdev), major, 1);
+    printk(KERN_DEBUG "Debug");
+    return 0;
+}
+
+static void __exit custom_exit(void) {
+    //Freeing buffer
+    unregister_chrdev_region(major, 1);
+    kfree(buff), buff = NULL;
+    cdev_del(&(peripherique.mycdev));
+}
+
+module_init(custom_init);
+module_exit(custom_exit);
\ No newline at end of file

abcd.mod.c

+#include <linux/module.h>
+#define INCLUDE_VERMAGIC
+#include <linux/build-salt.h>
+#include <linux/vermagic.h>
+#include <linux/compiler.h>
+
+BUILD_SALT;
+
+MODULE_INFO(vermagic, VERMAGIC_STRING);
+MODULE_INFO(name, KBUILD_MODNAME);
+
+__visible struct module __this_module
+__section(".gnu.linkonce.this_module") = {
+	.name = KBUILD_MODNAME,
+	.init = init_module,
+#ifdef CONFIG_MODULE_UNLOAD
+	.exit = cleanup_module,
+#endif
+	.arch = MODULE_ARCH_INIT,
+};
+
+#ifdef CONFIG_RETPOLINE
+MODULE_INFO(retpoline, "Y");
+#endif
+
+MODULE_INFO(depends, "");
+
+
+MODULE_INFO(srcversion, "907842194018E903497EAD0");