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

int main(){
	int fd = open("holes.txt",O_RDWR);
	size_t seek_point = ((size_t)1024)*1024*1024*1024*64;
	void *loc = mmap(0, seek_point + 40, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if ((ssize_t)loc == -1){
		perror("Mapping File");
		goto out;
	}
	printf("File contents from the beginning:  %s\n", loc);
	strcpy(loc + 10000, "A squirrel snuck under my bed.  I can tell, because it smells like rotten fish!\n");
	printf("File contents 10000 characters in:  %s\n", loc + 10000);
	printf("File contents after the hole:  %s\n", loc + seek_point);

	strcpy(loc + strlen(loc)-1, loc  + seek_point);
	ftruncate(fd, strlen(loc));	
	munmap(loc, seek_point + 40);
out:
	close(fd);
	return 0;
}