#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <unistd.h>
#include <errno.h>

int
main()
{
    int              kq, n;
    struct kevent    kev;
    struct timespec  to;

    kq = kqueue();
    if (kq == -1) {
        printf("kqueue() failed: (%d)%s\n", errno, strerror(errno));
        exit(1);
    }

    EV_SET(&kev, 0x55, EVFILT_USER, EV_ADD, 0, 0x1234, (void *) 0x5678);
    to.tv_sec = 0;
    to.tv_nsec = 0; 

    if (kevent(kq, &kev, 1, NULL, 0, &to) == -1) {
        printf("1st kevent() failed: (%d)%s\n", errno, strerror(errno));
        exit(1);
    }

    memset(&kev, 0, sizeof(struct kevent));

    if ((n = kevent(kq, NULL, 0, &kev, 1, &to)) == -1) {
        printf("2nd kevent() failed: (%d)%s\n", errno, strerror(errno));
        exit(1);
    }

    printf("n: %d, id: %p, filt: %d, fl: 0x%04X, ff:%u, data:%p, udata: %p\n",
           n, kev.ident, kev.filter, kev.flags, kev.fflags, kev.data, kev.udata);

    memset(&kev, 0, sizeof(struct kevent));

    if ((n = kevent(kq, NULL, 0, &kev, 1, &to)) == -1) {
        printf("3rd kevent() failed: (%d)%s\n", errno, strerror(errno));
        exit(1);
    }

    printf("n: %d, id: %p, filt: %d, fl: 0x%04X, ff:%u, data:%p, udata: %p\n",
           n, kev.ident, kev.filter, kev.flags, kev.fflags, kev.data, kev.udata);

    return 0;
}