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

int main(int argc, char **argv)
{
	struct stat stbuf;
	char *anon, *foo;
	int fd, i;

	fd = open(argv[1], O_RDWR);
	if (fd == -1)
		return 1;

	if (fstat(fd, &stbuf) == -1)
		return 1;

	anon = mmap(NULL, 10 * 4096, PROT_READ | PROT_WRITE,
		    MAP_SHARED | MAP_ANONYMOUS, -1, 0);
	if (anon == MAP_FAILED)
		return 1;

	foo = mmap(anon + 4096, 4096, PROT_READ | PROT_WRITE,
		   MAP_FIXED | MAP_SHARED, fd, 0);
	if (foo == MAP_FAILED) {
		printf("could not map\n");
		return 1;
	}

	for (i = 0; i < 10; i++)
		printf("first byte of page[%d] = 0x%02x\n", i, anon[i * 4096]);

	munmap(foo, 4096);

	for (i = 0; i < 10; i++)
		printf("first byte of page[%d] = 0x%02x\n", i, anon[i * 4096]);

	munmap(anon, 10 * 4096);

	close(fd);

	return 0;
}