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
rand_r(u_int * seed)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
rand(void)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
srand(u_int seed)64 srand(u_int seed)
65 {
66 rand_deterministic = 0;
67 }
68
69 void
srand_deterministic(u_int seed)70 srand_deterministic(u_int seed)
71 {
72 rand_deterministic = 1;
73 next = seed;
74 }
75