#include <stdio.h>
#include <string.h>
#include <sys/event.h>
#include <fcntl.h>
#include <errno.h>
#include <err.h>

int main()
{
    int fd = open("/dev/zero", O_RDONLY);
    int kq = kqueue();

    struct kevent kev;
    EV_SET(&kev, fd, EVFILT_READ, EV_ADD, 0, 0, NULL);

    errno = 0;
    int rc = kevent(kq, &kev, 1, NULL, 0, NULL);
    if (rc == -1)
    {
        errx(1, "kevent: %s", strerror(errno));
    }

    return 0;
}