1/*-
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>.
34 *
35 * $FreeBSD: head/lib/libc/stdlib/rand.c 75862 2001-04-23 10:14:28Z ache $
36 */
37
38#if defined(LIBC_SCCS) && !defined(lint)
39static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93";
40#endif /* LIBC_SCCS and not lint */
41
42#include <sys/time.h> /* for sranddev() */
43#include <sys/types.h>
44#include <fcntl.h> /* for sranddev() */
45#include <stdlib.h>
46#include <unistd.h> /* for sranddev() */
47
48#ifdef TEST
49#include <stdio.h>
50#endif /* TEST */
51
52static int
53do_rand(unsigned long *ctx)
54{
55#ifdef USE_WEAK_SEEDING
56/*
57 * Historic implementation compatibility.
58 * The random sequences do not vary much with the seed,
59 * even with overflowing.
60 */
61 return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
62#else /* !USE_WEAK_SEEDING */
63/*
64 * Compute x = (7^5 * x) mod (2^31 - 1)
65 * wihout overflowing 31 bits:
66 * (2^31 - 1) = 127773 * (7^5) + 2836
67 * From "Random number generators: good ones are hard to find",
68 * Park and Miller, Communications of the ACM, vol. 31, no. 10,
69 * October 1988, p. 1195.
70 */
71 long hi, lo, x;
72
73 hi = *ctx / 127773;
74 lo = *ctx % 127773;
75 x = 16807 * lo - 2836 * hi;
76 if (x <= 0)
77 x += 0x7fffffff;
78 return ((*ctx = x) % ((u_long)RAND_MAX + 1));
79#endif /* !USE_WEAK_SEEDING */
80}
81
82
83int
84rand_r(unsigned int *ctx)
85{
86 u_long val = (u_long) *ctx;
87 *ctx = do_rand(&val);
88 return (int) *ctx;
89}
90
91
92static u_long next = 1;
93
94int
95rand()
96{
97 return do_rand(&next);
98}
99
100void
101srand(seed)
102u_int seed;
103{
104 next = seed;
105}
106
107
108/*
109 * sranddev:
110 *
111 * Many programs choose the seed value in a totally predictable manner.
112 * This often causes problems. We seed the generator using the much more
113 * secure urandom(4) interface.
114 */
115void
116sranddev()
117{
118 int fd, done;
119
120 done = 0;
121 fd = _open("/dev/urandom", O_RDONLY, 0);
122 if (fd >= 0) {
123 if (_read(fd, (void *) &next, sizeof(next)) == sizeof(next))
124 done = 1;
125 _close(fd);
126 }
127
128 if (!done) {
129 struct timeval tv;
130 unsigned long junk;
131
132 gettimeofday(&tv, NULL);
133 next = (getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk;
134 }
135}
136
137
138#ifdef TEST
139
140main()
141{
142 int i;
143 unsigned myseed;
144
145 printf("seeding rand with 0x19610910: \n");
146 srand(0x19610910);
147
148 printf("generating three pseudo-random numbers:\n");
149 for (i = 0; i < 3; i++)
150 {
151 printf("next random number = %d\n", rand());
152 }
153
154 printf("generating the same sequence with rand_r:\n");
155 myseed = 0x19610910;
156 for (i = 0; i < 3; i++)
157 {
158 printf("next random number = %d\n", rand_r(&myseed));
159 }
160
161 return 0;
162}
163
164#endif /* TEST */
165
2 * Copyright (c) 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>.
34 *
35 * $FreeBSD: head/lib/libc/stdlib/rand.c 75862 2001-04-23 10:14:28Z ache $
36 */
37
38#if defined(LIBC_SCCS) && !defined(lint)
39static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93";
40#endif /* LIBC_SCCS and not lint */
41
42#include <sys/time.h> /* for sranddev() */
43#include <sys/types.h>
44#include <fcntl.h> /* for sranddev() */
45#include <stdlib.h>
46#include <unistd.h> /* for sranddev() */
47
48#ifdef TEST
49#include <stdio.h>
50#endif /* TEST */
51
52static int
53do_rand(unsigned long *ctx)
54{
55#ifdef USE_WEAK_SEEDING
56/*
57 * Historic implementation compatibility.
58 * The random sequences do not vary much with the seed,
59 * even with overflowing.
60 */
61 return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
62#else /* !USE_WEAK_SEEDING */
63/*
64 * Compute x = (7^5 * x) mod (2^31 - 1)
65 * wihout overflowing 31 bits:
66 * (2^31 - 1) = 127773 * (7^5) + 2836
67 * From "Random number generators: good ones are hard to find",
68 * Park and Miller, Communications of the ACM, vol. 31, no. 10,
69 * October 1988, p. 1195.
70 */
71 long hi, lo, x;
72
73 hi = *ctx / 127773;
74 lo = *ctx % 127773;
75 x = 16807 * lo - 2836 * hi;
76 if (x <= 0)
77 x += 0x7fffffff;
78 return ((*ctx = x) % ((u_long)RAND_MAX + 1));
79#endif /* !USE_WEAK_SEEDING */
80}
81
82
83int
84rand_r(unsigned int *ctx)
85{
86 u_long val = (u_long) *ctx;
87 *ctx = do_rand(&val);
88 return (int) *ctx;
89}
90
91
92static u_long next = 1;
93
94int
95rand()
96{
97 return do_rand(&next);
98}
99
100void
101srand(seed)
102u_int seed;
103{
104 next = seed;
105}
106
107
108/*
109 * sranddev:
110 *
111 * Many programs choose the seed value in a totally predictable manner.
112 * This often causes problems. We seed the generator using the much more
113 * secure urandom(4) interface.
114 */
115void
116sranddev()
117{
118 int fd, done;
119
120 done = 0;
121 fd = _open("/dev/urandom", O_RDONLY, 0);
122 if (fd >= 0) {
123 if (_read(fd, (void *) &next, sizeof(next)) == sizeof(next))
124 done = 1;
125 _close(fd);
126 }
127
128 if (!done) {
129 struct timeval tv;
130 unsigned long junk;
131
132 gettimeofday(&tv, NULL);
133 next = (getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk;
134 }
135}
136
137
138#ifdef TEST
139
140main()
141{
142 int i;
143 unsigned myseed;
144
145 printf("seeding rand with 0x19610910: \n");
146 srand(0x19610910);
147
148 printf("generating three pseudo-random numbers:\n");
149 for (i = 0; i < 3; i++)
150 {
151 printf("next random number = %d\n", rand());
152 }
153
154 printf("generating the same sequence with rand_r:\n");
155 myseed = 0x19610910;
156 for (i = 0; i < 3; i++)
157 {
158 printf("next random number = %d\n", rand_r(&myseed));
159 }
160
161 return 0;
162}
163
164#endif /* TEST */
165