/*      $OpenBSD: kqueue-random.c,v 1.13 2021/12/14 06:26:15 anton Exp $        */
/*      Written by Michael Shalayeff, 2002, Public Domain       */

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

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

#include "main.h"

#define MINIMUM(a, b)    (((a) < (b)) ? (a) : (b))

int
do_random(void)
{
        int n, fd, kq;
        struct timespec ts;
        struct kevent ev;
        u_int32_t buf[BUFSIZ];

        ASS((fd = open("/dev/random", O_RDONLY)) >= 0,
            warn("open: /dev/random"));
        ASS(fcntl(fd, F_SETFL, O_NONBLOCK) == 0,
            warn("fcntl"));

        ASS((kq = kqueue()) >= 0,
            warn("kqueue"));

        memset(&ev, 0, sizeof(ev));
        ev.ident = fd;
        ev.filter = EVFILT_READ;
        ev.flags = EV_ADD | EV_ENABLE;
        n = kevent(kq, &ev, 1, NULL, 0, NULL);
        ASSX(n != -1);

        ts.tv_sec = 0;
        ts.tv_nsec = 0;
        n = kevent(kq, NULL, 0, &ev, 1, &ts);
        ASSX(n >= 0);

        n = MINIMUM((ev.data + 7) / 8, sizeof(buf));
        ASSX(read(fd, buf, n) > 0);

        close(kq);
        close(fd);

        return (0);
}