1356143Scy/*	$OpenBSD: getentropy_freebsd.c,v 1.3 2016/08/07 03:27:21 tb Exp $	*/
2356143Scy
3356143Scy/*
4356143Scy * Copyright (c) 2014 Pawel Jakub Dawidek <pjd@FreeBSD.org>
5356143Scy * Copyright (c) 2014 Brent Cook <bcook@openbsd.org>
6356143Scy *
7356143Scy * Permission to use, copy, modify, and distribute this software for any
8356143Scy * purpose with or without fee is hereby granted, provided that the above
9356143Scy * copyright notice and this permission notice appear in all copies.
10356143Scy *
11356143Scy * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12356143Scy * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13356143Scy * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14356143Scy * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15356143Scy * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16356143Scy * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17356143Scy * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18356143Scy *
19356143Scy * Emulation of getentropy(2) as documented at:
20356143Scy * http://man.openbsd.org/getentropy.2
21356143Scy */
22356143Scy
23356143Scy#include <sys/types.h>
24356143Scy#include <sys/sysctl.h>
25356143Scy
26356143Scy#include <errno.h>
27356143Scy#include <stddef.h>
28356143Scy
29356143Scy/*
30356143Scy * Derived from lib/libc/gen/arc4random.c from FreeBSD.
31356143Scy */
32356143Scystatic size_t
33356143Scygetentropy_sysctl(u_char *buf, size_t size)
34356143Scy{
35356143Scy	int mib[2];
36356143Scy	size_t len, done;
37356143Scy
38356143Scy	mib[0] = CTL_KERN;
39356143Scy	mib[1] = KERN_ARND;
40356143Scy	done = 0;
41356143Scy
42356143Scy	do {
43356143Scy		len = size;
44356143Scy		if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
45356143Scy			return (done);
46356143Scy		done += len;
47356143Scy		buf += len;
48356143Scy		size -= len;
49356143Scy	} while (size > 0);
50356143Scy
51356143Scy	return (done);
52356143Scy}
53356143Scy
54356143Scyint
55356143Scygetentropy(void *buf, size_t len)
56356143Scy{
57356143Scy	if (len <= 256 && getentropy_sysctl(buf, len) == len)
58356143Scy		return (0);
59356143Scy
60356143Scy	errno = EIO;
61356143Scy	return (-1);
62356143Scy}
63