1 /* $OpenBSD: getentropy_freebsd.c,v 1.3 2016/08/07 03:27:21 tb Exp $ */
2
3 /*
4 * Copyright (c) 2014 Pawel Jakub Dawidek <pjd@FreeBSD.org>
5 * Copyright (c) 2014 Brent Cook <bcook@openbsd.org>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 *
19 * Emulation of getentropy(2) as documented at:
20 * http://man.openbsd.org/getentropy.2
21 */
22
23 #include <sys/types.h>
24 #include <sys/sysctl.h>
25
26 #include <errno.h>
27 #include <stddef.h>
28
29 /*
30 * Derived from lib/libc/gen/arc4random.c from FreeBSD.
31 */
32 static size_t
getentropy_sysctl(u_char * buf,size_t size)33 getentropy_sysctl(u_char *buf, size_t size)
34 {
35 int mib[2];
36 size_t len, done;
37
38 mib[0] = CTL_KERN;
39 mib[1] = KERN_ARND;
40 done = 0;
41
42 do {
43 len = size;
44 if (sysctl(mib, 2, buf, &len, NULL, 0) == -1)
45 return (done);
46 done += len;
47 buf += len;
48 size -= len;
49 } while (size > 0);
50
51 return (done);
52 }
53
54 int
getentropy(void * buf,size_t len)55 getentropy(void *buf, size_t len)
56 {
57 if (len <= 256 && getentropy_sysctl(buf, len) == len)
58 return (0);
59
60 errno = EIO;
61 return (-1);
62 }
63