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 } 63