lib/libcrypto/arc4random/getentropy_freebsd.c

   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
  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
  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 }