#include <err.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>

int
main(void)
{
	char buf[100];
	int fd;

	fd = open("crapfile", O_RDONLY|O_CREAT, 0600);
	if (fd == -1)
		err(1, "open");
	if (fcntl(fd, F_READAHEAD, 100) == -1)
		err(1, "fcntl");
	if (read(fd, buf, sizeof(buf)) == -1)
		err(1, "read");
	if (fcntl(fd, F_READAHEAD, -1) == -1)
		err(1, "fcntl");
	if (read(fd, buf, sizeof(buf)) == -1)
		err(1, "read");
	if (fcntl(fd, F_READAHEAD, 100) == -1)
		err(1, "fcntl");
	if (read(fd, buf, sizeof(buf)) == -1)
		err(1, "read");
	close(fd);
	unlink("crapfile");
	return (0);
}