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

int main(int argc, char **argv)
{
	char *mapping;
	int fd;

	fd = open("mapfile", O_RDWR | O_TRUNC | O_CREAT, 0666);
	if (fd < 0)
		return -1;
	if (ftruncate(fd, 10) < 0)
		return -1;
	mapping = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (-1 == (int)(long)mapping)
		return -1;
	memset(mapping, 0x55, 10);
	if (ftruncate(fd, 100) < 0)
		return -1;
	memset(mapping, 0xaa, 200);
	if (ftruncate(fd, 200) < 0)
		return -1;
	return 0;
}