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 34 static int rand_deterministic; 35 static u_int next = 1; 36 37 int 38 rand_r(u_int *seed) 39 { 40 *seed = *seed * 1103515245 + 12345; 41 return (*seed & RAND_MAX); 42 } 43 DEF_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 50 int 51 rand(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 63 void 64 srand(u_int seed) 65 { 66 rand_deterministic = 0; 67 } 68 69 void 70 srand_deterministic(u_int seed) 71 { 72 rand_deterministic = 1; 73 next = seed; 74 } 75