创建固定大小文件并通过mmap的操作-lubing521-ChinaUnix博客

* =====================================================================================

* Filename: file_map.cpp

* Description:

* Version: 1.0

* Created: 2012年07月19日 10时08分07秒

* Revision: none

* Compiler: gcc

* Author: YOUR NAME (),

* Company:

* =====================================================================================

#include

using namespace std;

const char text[]="hello,world !";

int main(void){

int fd;

struct stat buf;

int rc;

void *fdstart;

fd=open("./log.bin",O_CREAT|O_RDWR,777);

if(fd<0){

printf("open log.bin fail\n");

}

if(truncate("./log.bin",1024) < 0){

cout<< "truncate error !"<

}

rc=fstat(fd,&buf);

if(rc == -1){

printf("File Size %d \n",buf.st_size);

}

cout << "buf.st_size %d "<

if((fdstart=mmap(NULL,buf.st_size,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0))==MAP_FAILED){

cout<<"mmap error!"<

close(fd);

exit(0);

}

cout <<"text size %d "<< sizeof(text)<

memcpy(fdstart,(void *)text,sizeof(text));

munmap(fdstart,buf.st_size);

close(fd);

return EXIT_SUCCESS;

}

编译后运行结果如下：

[root@localhost epoll]# ./mmp

buf.st_size %d 1024

text size %d 14

[root@localhost epoll]# cat log.bin

hello,world ![root@localhost epoll]# gedit file_map.cpp

[root@localhost epoll]#