1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>. 32 */ 33 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93"; 36 #endif /* LIBC_SCCS and not lint */ 37 #include <sys/cdefs.h> 38 __FBSDID("$FreeBSD$"); 39 40 #include "namespace.h" 41 #include <sys/param.h> 42 #include <sys/sysctl.h> 43 #include <stdbool.h> 44 #include <stdlib.h> 45 #include <syslog.h> 46 #include "un-namespace.h" 47 48 #ifdef TEST 49 #include <stdio.h> 50 #endif /* TEST */ 51 52 static int 53 do_rand(unsigned long *ctx) 54 { 55 /* 56 * Compute x = (7^5 * x) mod (2^31 - 1) 57 * without overflowing 31 bits: 58 * (2^31 - 1) = 127773 * (7^5) + 2836 59 * From "Random number generators: good ones are hard to find", 60 * Park and Miller, Communications of the ACM, vol. 31, no. 10, 61 * October 1988, p. 1195. 62 */ 63 long hi, lo, x; 64 65 /* Transform to [1, 0x7ffffffe] range. */ 66 x = (*ctx % 0x7ffffffe) + 1; 67 hi = x / 127773; 68 lo = x % 127773; 69 x = 16807 * lo - 2836 * hi; 70 if (x < 0) 71 x += 0x7fffffff; 72 /* Transform to [0, 0x7ffffffd] range. */ 73 x--; 74 *ctx = x; 75 return (x); 76 } 77 78 79 int 80 rand_r(unsigned *ctx) 81 { 82 u_long val; 83 int r; 84 85 val = *ctx; 86 r = do_rand(&val); 87 *ctx = (unsigned)val; 88 return (r); 89 } 90 91 92 static u_long next = 1; 93 94 int 95 rand(void) 96 { 97 return (do_rand(&next)); 98 } 99 100 void 101 srand(unsigned seed) 102 { 103 next = seed; 104 } 105 106 107 void __sranddev_fbsd12(void); 108 void 109 __sranddev_fbsd12(void) 110 { 111 static bool warned = false; 112 113 if (!warned) { 114 syslog(LOG_DEBUG, "Deprecated function sranddev() called"); 115 warned = true; 116 } 117 } 118 __sym_compat(sranddev, __sranddev_fbsd12, FBSD_1.0); 119 120 121 #ifdef TEST 122 123 main() 124 { 125 int i; 126 unsigned myseed; 127 128 printf("seeding rand with 0x19610910: \n"); 129 srand(0x19610910); 130 131 printf("generating three pseudo-random numbers:\n"); 132 for (i = 0; i < 3; i++) 133 { 134 printf("next random number = %d\n", rand()); 135 } 136 137 printf("generating the same sequence with rand_r:\n"); 138 myseed = 0x19610910; 139 for (i = 0; i < 3; i++) 140 { 141 printf("next random number = %d\n", rand_r(&myseed)); 142 } 143 144 return 0; 145 } 146 147 #endif /* TEST */ 148 149