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#include <sys/ioctl.h> int ioctl(int d, int request, ...); |
Linux 헤더 파일 "/usr/include/asm/ioctl.h" 는 ioctl의 커맨드 번호를 작성하는데 사용해야하는 매크로가 정의되어 있습니다.
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struct ioctl_info{
unsigned long size;
unsigned int buf[128];
};
#define IOCTL_MAGIC 'G'
#define SET_DATA _IOW(IOCTL_MAGIC, 2 , ioctl_info )
#define GET_DATA _IOR(IOCTL_MAGIC, 3 , ioctl_info ) |
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#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <asm/current.h>
#include <linux/uaccess.h>
#include "chardev.h"
MODULE_LICENSE("Dual BSD/GPL");
#define DRIVER_NAME "chardev"
static const unsigned int MINOR_BASE = 0;
static const unsigned int MINOR_NUM = 1;
static unsigned int chardev_major;
static struct cdev chardev_cdev;
static struct class *chardev_class = NULL;
static int chardev_open(struct inode *, struct file *);
static int chardev_release(struct inode *, struct file *);
static ssize_t chardev_read(struct file *, char *, size_t, loff_t *);
static ssize_t chardev_write(struct file *, const char *, size_t, loff_t *);
static long chardev_ioctl(struct file *, unsigned int, unsigned long);
struct file_operations s_chardev_fops = {
.open = chardev_open,
.release = chardev_release,
.read = chardev_read,
.write = chardev_write,
.unlocked_ioctl = chardev_ioctl,
};
static int chardev_init(void)
{
int alloc_ret = 0;
int cdev_err = 0;
int minor = 0;
dev_t dev;
printk("The chardev_init() function has been called.");
alloc_ret = alloc_chrdev_region(&dev, MINOR_BASE, MINOR_NUM, DRIVER_NAME);
if (alloc_ret != 0) {
printk(KERN_ERR "alloc_chrdev_region = %d\n", alloc_ret);
return -1;
}
//Get the major number value in dev.
chardev_major = MAJOR(dev);
dev = MKDEV(chardev_major, MINOR_BASE);
//initialize a cdev structure
cdev_init(&chardev_cdev, &s_chardev_fops);
chardev_cdev.owner = THIS_MODULE;
//add a char device to the system
cdev_err = cdev_add(&chardev_cdev, dev, MINOR_NUM);
if (cdev_err != 0) {
printk(KERN_ERR "cdev_add = %d\n", alloc_ret);
unregister_chrdev_region(dev, MINOR_NUM);
return -1;
}
chardev_class = class_create(THIS_MODULE, "chardev");
if (IS_ERR(chardev_class)) {
printk(KERN_ERR "class_create\n");
cdev_del(&chardev_cdev);
unregister_chrdev_region(dev, MINOR_NUM);
return -1;
}
device_create(chardev_class, NULL, MKDEV(chardev_major, minor), NULL, "chardev%d", minor);
return 0;
}
static void chardev_exit(void)
{
int minor = 0;
dev_t dev = MKDEV(chardev_major, MINOR_BASE);
printk("The chardev_exit() function has been called.");
device_destroy(chardev_class, MKDEV(chardev_major, minor));
class_destroy(chardev_class);
cdev_del(&chardev_cdev);
unregister_chrdev_region(dev, MINOR_NUM);
}
static int chardev_open(struct inode *inode, struct file *file)
{
printk("The chardev_open() function has been called.");
return 0;
}
static int chardev_release(struct inode *inode, struct file *file)
{
printk("The chardev_close() function has been called.");
return 0;
}
static ssize_t chardev_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)
{
printk("The chardev_write() function has been called.");
return count;
}
static ssize_t chardev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
printk("The chardev_read() function has been called.");
return count;
}
static struct ioctl_info info;
static long chardev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
printk("The chardev_ioctl() function has been called.");
switch (cmd) {
case SET_DATA:
printk("SET_DATA\n");
if (copy_from_user(&info, (void __user *)arg, sizeof(info))) {
return -EFAULT;
}
printk("info.size : %ld, info.buf : %s",info.size, info.buf);
break;
case GET_DATA:
printk("GET_DATA\n");
if (copy_to_user((void __user *)arg, &info, sizeof(info))) {
return -EFAULT;
}
break;
default:
printk(KERN_WARNING "unsupported command %d\n", cmd);
return -EFAULT;
}
return 0;
}
module_init(chardev_init);
module_exit(chardev_exit); |
#ifndef CHAR_DEV_H_
#define CHAR_DEV_H_
#include <linux/ioctl.h>
struct ioctl_info{
unsigned long size;
char buf[128];
};
#define IOCTL_MAGIC 'G'
#define SET_DATA _IOW(IOCTL_MAGIC, 2 ,struct ioctl_info)
#define GET_DATA _IOR(IOCTL_MAGIC, 3 ,struct ioctl_info)
#endif |
obj-m := chardev.o all: make -C /lib/modules/$(shell uname -r)/build M=$(shell pwd) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(shell pwd) clean |
테스트 프로그램은 다음과 같이 동작합니다.
open() 함수를 이용하여 "/dev/chardev0" 파일을 열어 fd값을 얻습니다.
ioctl() 함수를 이용하여 사용자 공간에 저장된 데이터를 커널 영역에 데이터를 복사하기 위해 fd, "SET_DATA", 커널에 저장할 데이터를 인자 값(&set_info)으로 전달합니다.
ioctl() 함수를 이용하여 커널 영역에 저장된 데이터를 사용가 공간으로 복사하기 위해 fd, "GET_DATA", 사용자 공간에에 데이터를 저장할 변수를 인자 값(&get_info)으로 전달합니다.
printf() 함수를 이용하여 사용자 공간에 복사된 데이터를 출력합니다.
close() 함수를 이용하여 fd를 닫습니다.
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/ioctl.h>
#include "chardev.h"
int main()
{
int fd;
struct ioctl_info set_info;
struct ioctl_info get_info;
set_info.size = 100;
strncpy(set_info.buf,"lazenca.0x0",11);
if ((fd = open("/dev/chardev0", O_RDWR)) < 0){
printf("Cannot open /dev/chardev0. Try again later.\n");
}
if (ioctl(fd, SET_DATA, &set_info) < 0){
printf("Error : SET_DATA.\n");
}
if (ioctl(fd, GET_DATA, &get_info) < 0){
printf("Error : SET_DATA.\n");
}
printf("get_info.size : %ld, get_info.buf : %s\n", get_info.size, get_info.buf);
if (close(fd) != 0){
printf("Cannot close.\n");
}
return 0;
} |
lazenca0x0@ubuntu:~/Kernel/Module/ioctl$ make make -C /lib/modules/4.18.0-11-generic/build M=/home/lazenca0x0/Kernel/Module/ioctl modules make[1]: Entering directory '/usr/src/linux-headers-4.18.0-11-generic' Makefile:982: "Cannot use CONFIG_STACK_VALIDATION=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel" CC [M] /home/lazenca0x0/Kernel/Module/ioctl/chardev.o Building modules, stage 2. MODPOST 1 modules CC /home/lazenca0x0/Kernel/Module/ioctl/chardev.mod.o LD [M] /home/lazenca0x0/Kernel/Module/ioctl/chardev.ko make[1]: Leaving directory '/usr/src/linux-headers-4.18.0-11-generic' lazenca0x0@ubuntu:~/Kernel/Module/ioctl$ sudo insmod chardev.ko [sudo] password for lazenca0x0: lazenca0x0@ubuntu:~/Kernel/Module/ioctl$ ./test get_info.size : 100, get_info.buf : lazenca.0x0 lazenca0x0@ubuntu:~/Kernel/Module/ioctl$ dmesg |tail [ 53.358158] rfkill: input handler disabled [ 97.190519] chardev: loading out-of-tree module taints kernel. [ 97.190571] chardev: module verification failed: signature and/or required key missing - tainting kernel [ 97.191019] The chardev_init() function has been called. [ 117.777326] The chardev_open() function has been called. [ 117.777328] The chardev_ioctl() function has been called. [ 117.777329] SET_DATA [ 117.777330] info.size : 100, info.buf : lazenca.0x0 [ 117.777331] The chardev_ioctl() function has been called. [ 117.777331] GET_DATA lazenca0x0@ubuntu:~/Kernel/Module/ioctl$ |