xref: /src/lib/libc/gen/getentropy.c

/*	$NetBSD: getentropy.c,v 1.3 2022/05/31 13:42:59 riastradh Exp $	*/

/*-
 * Copyright (c) 2020 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Nia Alarie.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__RCSID("$NetBSD: getentropy.c,v 1.3 2022/05/31 13:42:59 riastradh Exp $");

#include "namespace.h"

#include <sys/param.h>
#include <sys/sysctl.h>

#include <errno.h>
#include <limits.h>
#include <unistd.h>

#ifdef __weak_alias
__weak_alias(getentropy,_getentropy)
#endif

__CTASSERT(GETENTROPY_MAX == 256);

int
getentropy(void *buf, size_t buflen)
{
	size_t len = buflen;
	int name[2] = { CTL_KERN, KERN_ARND };

	if (buf == NULL && buflen > 0) {
		errno = EFAULT;
		return -1;
	}

	if (buflen > 256) {
		errno = EINVAL;
		return -1;
	}

	return sysctl(name, 2, buf, &len, NULL, 0);
}