lseek产生空洞文件

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>

int main (int argc,char* argv[]){
        int fd;
        if((fd = creat("file.hole",O_CREAT))<0)
                perror("creat error!!");
        if(write(fd,"abcdefghij",10)!=10)
                perror("wirte error!!");
        if(lseek(fd,40,SEEK_SET)==-1)
                perror("lseek error!!!");
        if(write(fd,"ABCEDFGHIJ",10)!=10)
                perror("wirte2  error!!");

        return 0;
}