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/* $OpenBSD: kqueue-random.c,v 1.12 2021/12/13 16:56:49 deraadt Exp $ */
/* Written by Michael Shalayeff, 2002, Public Domain */
#include <sys/types.h>
#include <sys/event.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);
}
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