#include <sys/types.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/uio.h>

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

int
main()
{
	struct iovec iov[2];
	size_t psz;
	char *a, *b;
	int fd, rv;

	psz = getpagesize();
	a = mmap(NULL, psz, PROT_NONE, MAP_ANON, -1, 0);
	if (a == MAP_FAILED)
		err(1, "mmap 1");
	b = mmap(a + psz, psz, PROT_READ, MAP_ANON | MAP_FIXED, -1, 0);
	if (b == MAP_FAILED)
		err(1, "mmap 2");
	fd = open("uiob.foo", O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
	if (fd == -1)
		err(1, "open");
	iov[0].iov_base = a;
	iov[0].iov_len = psz;
	iov[1].iov_base = b;
	iov[1].iov_len = psz;
	rv = writev(fd, iov, 2);
	printf("writev returned %d\n", rv);
	if (rv == -1)
		printf("error %s\n", strerror(errno));
	close(fd);
	return (0);
}