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/* $OpenBSD: getentropy_freebsd.c,v 1.2 2015/08/25 17:22:56 deraadt Exp $ */
/*
* Copyright (c) 2014 Pawel Jakub Dawidek <pjd@FreeBSD.org>
* Copyright (c) 2014 Brent Cook <bcook@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Emulation of getentropy(2) as documented at:
* http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man2/getentropy.2
*/
#include <sys/types.h>
#include <sys/sysctl.h>
#include <errno.h>
#include <stddef.h>
/*
* Derived from lib/libc/gen/arc4random.c from FreeBSD.
*/
static size_t
getentropy_sysctl(u_char *buf, size_t size)
{
int mib[2];
size_t len, done;
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
done = 0;
do {
len = size;
if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
return (done);
done += len;
buf += len;
size -= len;
} while (size > 0);
return (done);
}
int
getentropy(void *buf, size_t len)
{
if (len <= 256 && getentropy_sysctl(buf, len) == len)
return (0);
errno = EIO;
return (-1);
}
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