rand.c revision 1.18
1/* $OpenBSD: rand.c,v 1.18 2017/11/28 06:55:49 tb Exp $ */ 2/*- 3 * Copyright (c) 1990 The Regents of the University of California. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31#include <sys/types.h> 32#include <stdlib.h> 33 34static int rand_deterministic; 35static u_int next = 1; 36 37int 38rand_r(u_int *seed) 39{ 40 *seed = *seed * 1103515245 + 12345; 41 return (*seed & RAND_MAX); 42} 43DEF_WEAK(rand_r); 44 45#if defined(APIWARN) 46__warn_references(rand_r, 47 "rand_r() is not random, it is deterministic."); 48#endif 49 50int 51rand(void) 52{ 53 if (rand_deterministic == 0) 54 return (arc4random() & RAND_MAX); 55 return (rand_r(&next)); 56} 57 58#if defined(APIWARN) 59__warn_references(rand, 60 "rand() may return deterministic values, is that what you want?"); 61#endif 62 63void 64srand(u_int seed) 65{ 66 rand_deterministic = 0; 67} 68 69void 70srand_deterministic(u_int seed) 71{ 72 rand_deterministic = 1; 73 next = seed; 74} 75