帮我写一个内核和应用层交互的源码
时间: 2023-08-28 09:37:21 浏览: 47
好的,下面是一个简单的内核和应用层交互的源码,其中使用了字符设备驱动来实现:
首先是头文件部分:
```
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/uaccess.h>
```
然后定义一个设备结构体,并在模块初始化函数中注册设备:
```
static dev_t devno;
static struct cdev mycdev;
static struct class *myclass;
static char buf[256];
static int len;
static DEFINE_MUTEX(mutex);
static ssize_t myread(struct file *file, char __user *buff,
size_t count, loff_t *ppos)
{
int ret;
mutex_lock(&mutex);
if (*ppos >= len)
ret = 0;
else {
if (count > len - *ppos)
count = len - *ppos;
if (copy_to_user(buff, buf + *ppos, count)) {
ret = -EFAULT;
goto out;
}
*ppos += count;
ret = count;
}
out:
mutex_unlock(&mutex);
return ret;
}
static ssize_t mywrite(struct file *file, const char __user *buff,
size_t count, loff_t *ppos)
{
int ret;
mutex_lock(&mutex);
if (count > sizeof(buf))
count = sizeof(buf);
if (copy_from_user(buf, buff, count)) {
ret = -EFAULT;
goto out;
}
len = count;
ret = count;
out:
mutex_unlock(&mutex);
return ret;
}
static struct file_operations fops = {
.owner = THIS_MODULE,
.read = myread,
.write = mywrite,
};
static int __init mymodule_init(void)
{
int ret;
ret = alloc_chrdev_region(&devno, 0, 1, "mydev");
if (ret) {
printk(KERN_ERR "alloc_chrdev_region error\n");
return ret;
}
cdev_init(&mycdev, &fops);
mycdev.owner = THIS_MODULE;
ret = cdev_add(&mycdev, devno, 1);
if (ret) {
printk(KERN_ERR "cdev_add error\n");
unregister_chrdev_region(devno, 1);
return ret;
}
myclass = class_create(THIS_MODULE, "myclass");
if (IS_ERR(myclass)) {
printk(KERN_ERR "class_create error\n");
cdev_del(&mycdev);
unregister_chrdev_region(devno, 1);
return PTR_ERR(myclass);
}
device_create(myclass, NULL, devno, NULL, "mydev");
return 0;
}
static void __exit mymodule_exit(void)
{
device_destroy(myclass, devno);
class_destroy(myclass);
cdev_del(&mycdev);
unregister_chrdev_region(devno, 1);
}
module_init(mymodule_init);
module_exit(mymodule_exit);
MODULE_LICENSE("GPL");
```
接下来是应用层的代码,其中打开设备、写入数据、读取数据和关闭设备:
```
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
int main(int argc, char *argv[])
{
int fd;
char buf[256];
int len;
fd = open("/dev/mydev", O_RDWR);
if (fd < 0) {
perror("open");
exit(1);
}
len = write(fd, "Hello, World!", strlen("Hello, World!"));
if (len < 0) {
perror("write");
exit(1);
}
len = read(fd, buf, sizeof(buf));
if (len < 0) {
perror("read");
exit(1);
}
buf[len] = '\0';
printf("%s\n", buf);
close(fd);
return 0;
}
```
这个源码实现了一个简单的内核和应用层交互机制,其中应用层通过打开设备、写入数据、读取数据和关闭设备来实现与内核的交互,内核通过字符设备驱动来实现对应的功能。当然这只是一个简单的示例,实际中可能需要更加复杂的实现。