a subset of kevent fails to work with setuid()

[Luke Small]

The other kevent calls I use seem to work alright, but when run as root,
this fails.

#include <err.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/event.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>

int
main()
{
    pid_t pid;
    int kq;
    struct kevent ke;


    printf("\nUID: %u\n", getuid());

    setuid(1000);

    printf("UID: %u\n\n", getuid(), geteuid());

    kq = kqueue();
    if (kq == -1)
        errx(1, "kq!");

    pid = fork();
    if (pid == (pid_t) 0) {
        sleep(2);
        printf("done\n");
        _exit(0);
    }
    if (pid == -1)
        err(1, NULL);
    EV_SET(&ke, pid, EVFILT_PROC, EV_ADD | EV_ONESHOT,
        NOTE_EXIT, 0, NULL);
    if (kevent(kq, &ke, 1, NULL, 0, NULL) == -1) {
        kill(pid, SIGKILL);
        err(EXIT_FAILURE, "kevent register fail.");
    }

    wait(0);
    return 0;
}

-Luke