read/write proc例程

来源：互联网发布：查车档案软件编辑：程序博客网时间：2024/06/06 03:27

Proc做为用户态进程和内核进行通信的工具，可以用Proc访问内核的数据，本文例程创建一个Proc，然后通过一个Hello world例程进行Proc的读写操作。

Proc的源代码：(此代码转自：http://tuxthink.blogspot.com/2011/02/creating-readwrite-proc-entry.html)

/*************************************************************************> File Name: proc_write_read.c> Author: > Mail: > Created Time: Mon 20 Apr 2015 01:57:22 PM CST ************************************************************************/#include <linux/module.h>#include <linux/kernel.h>#include <asm/uaccess.h>#include <linux/cdev.h>#include <linux/proc_fs.h>#define MAX_PROC_SIZE 100static char proc_data[MAX_PROC_SIZE];static struct proc_dir_entry *proc_write_entry;int read_proc(char *buf,char **start,off_t offset,int count,int *eof,void *data ){    int len=0;     len = sprintf(buf,"%s",proc_data);    return len;}int write_proc(struct file *file,const char *buf,int count,void *data ){    if(count > MAX_PROC_SIZE)        count = MAX_PROC_SIZE;    if(copy_from_user(proc_data, buf, count))        return -EFAULT;    return count;}void create_new_proc_entry(){    proc_write_entry = create_proc_entry("proc_entry",0666,NULL);    if(!proc_write_entry)    {            printk(KERN_INFO "Error creating proc entry");            return -ENOMEM;                }    proc_write_entry->read_proc = read_proc ;    proc_write_entry->write_proc = write_proc;    printk(KERN_INFO "proc initialized");}int proc_init (void) {        create_new_proc_entry();        return 0;}void proc_cleanup(void) {        printk(KERN_INFO " Inside cleanup_module\n");        remove_proc_entry("proc_entry",NULL);}MODULE_LICENSE("GPL");   module_init(proc_init);module_exit(proc_cleanup);

Makefile文件

ifneq ($(KERNELRELEASE),)    obj-m := proc_write_read.o   aa=1234else aa=4567KERNELDIR ?= /lib/modules/$(shell uname -r)/build PWD := $(shell pwd)default:  $(MAKE) -C $(KERNELDIR) M=$(PWD) modules @echo $(aa)endif clean: $(MAKE) -C $(KERNELDIR) M=$(PWD) clean @echo $(aa)

通过Make命令可以生成proc_write_read.ko 模块文件。

加载模块：

sudo insmod proc_write_read.ko

卸载模块：

sudo rmmod proc_write_read.ko

读写Proc的例程：

/*************************************************************************> File Name: test_proc_writeread.c> Author: > Mail: > Created Time: Mon 20 Apr 2015 02:45:58 PM CST ************************************************************************/#include<stdio.h>int main(int argc, char * argv[]){    FILE *fd_read, *fd_write = NULL;    char data1[30] = {0};    char data2[30] = {0};    memcpy(data1, "Hello World!!!", 30);#if 1    fd_write = fopen("/proc/proc_entry", "w");    if(NULL == fd_write)    {        return -1;    }    printf("write \"%s\" to proc_entry", data1);    fwrite(data1, 1, sizeof(data1), fd_write);    fclose(fd_write);#endif    printf("\r\n~~~~~~~~~~~~~~~~~~~~~\r\n");    fd_read = fopen("/proc/proc_entry", "r");    if(NULL == fd_read)    {        return -1;    }    fread(data2, 1, sizeof(data2), fd_read);    printf("read data \"%s\" \nend\n", data2);    fclose(fd_read);    return 0;}

编译生成test程序

cc -o test test_proc_writeread.c

运行test

结果如下：

write "Hello World!!!" to proc_entry
~~~~~~~~~~~~~~~~~~~~~
read data "Hello World!!!"
end

0 0