linux 創建proc 文件

 

testproc.c
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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/proc_fs.h>

#include <asm/uaccess.h>

#define MESSAGE_LENGTH 80
static char Message[MESSAGE_LENGTH] = "Helloworld\n";

static int read_procmem( char *buf, char **start, off_t offset,
                int count, int *eof, void *data)
{
        *eof = 1;                   //說明已經讀完
        strcpy(buf, Message);
        return strlen(Message);     //返回讀入的字符數
}

static int write_procmem( struct file *file, const char *buffer,
                        unsigned long count, void *data)
{
        strcpy(Message, buffer);
        return strlen(Message);     //返回寫入的字符數
}

static int __init init( void )
{
        struct proc_dir_entry *p;

        mode_t mode = S_IFREG | S_IWUGO | S_IRUGO;
//                             什麼人都能寫 | 什麼人都能讀
        p = create_proc_entry("abcdef",     //proc文件名
                        mode,
                        NULL);              //父目錄, NULL就是/proc目錄

        if ( !p ) {
                return ( -EINVAL );
        }
        p->size = 2131;             //對外顯示的文件大小
        p->owner = THIS_MODULE;
        p->read_proc = read_procmem;
        p->write_proc = write_procmem;

        return 0;
}

static void __exit cleanup( void )
{
        remove_proc_entry("abcdef", NULL);
}

module_init( init );
module_exit( cleanup );
MODULE_LICENSE("GPL");
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Makefile
-----------------------------------------------------
KERNELDIR=/usr/src/linux

include $(KERNELDIR)/.config

CFLAGS = -D__KERNEL__ -DMODULE -I$(KERNELDIR)/include -O -Wall

ifdef CONFIG_SMP
        CFLAGS += -D__SMP__ -DSMP
endif

all:testproc.o

clean:
        rm -f *.o *~ core
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然後切換到root用戶試試
#insmod testproc.o
#ls /proc/abcdef -l
-rw-rw-rw-    1 root     root         2131 Apr  9 23:04 /proc/abcdef
#cat /proc/abcdef
Helloworld
#echo hahaha >/proc/abcdef
#cat /proc/abcdef
hahaha
#rmmod testproc