lua-arc4random

Cryptographically secure PRNG for Lua
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getentropy_freebsd.c (1663B)


      1 /*	$OpenBSD: getentropy_osx.c,v 1.7 2014/07/19 16:12:00 deraadt 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://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man2/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 &&
     58 			getentropy_sysctl(buf, len) == len) {
     59 		return 0;
     60 	}
     61 
     62 	errno = EIO;
     63 	return -1;
     64 }