08ef412169
source sysctl(KERN_ARND) and remove the fallback code. Obtained from: OpenBSD Reviewed by: secteam MFC after: 1 month
159 lines
3.9 KiB
C
159 lines
3.9 KiB
C
/*-
|
|
* Copyright (c) 1990, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>.
|
|
*/
|
|
|
|
#if defined(LIBC_SCCS) && !defined(lint)
|
|
static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93";
|
|
#endif /* LIBC_SCCS and not lint */
|
|
#include <sys/cdefs.h>
|
|
__FBSDID("$FreeBSD$");
|
|
|
|
#include "namespace.h"
|
|
#include <sys/param.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/types.h>
|
|
#include <stdlib.h>
|
|
#include "un-namespace.h"
|
|
|
|
#ifdef TEST
|
|
#include <stdio.h>
|
|
#endif /* TEST */
|
|
|
|
static int
|
|
do_rand(unsigned long *ctx)
|
|
{
|
|
#ifdef USE_WEAK_SEEDING
|
|
/*
|
|
* Historic implementation compatibility.
|
|
* The random sequences do not vary much with the seed,
|
|
* even with overflowing.
|
|
*/
|
|
return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
|
|
#else /* !USE_WEAK_SEEDING */
|
|
/*
|
|
* Compute x = (7^5 * x) mod (2^31 - 1)
|
|
* without overflowing 31 bits:
|
|
* (2^31 - 1) = 127773 * (7^5) + 2836
|
|
* From "Random number generators: good ones are hard to find",
|
|
* Park and Miller, Communications of the ACM, vol. 31, no. 10,
|
|
* October 1988, p. 1195.
|
|
*/
|
|
long hi, lo, x;
|
|
|
|
/* Can't be initialized with 0, so use another value. */
|
|
if (*ctx == 0)
|
|
*ctx = 123459876;
|
|
hi = *ctx / 127773;
|
|
lo = *ctx % 127773;
|
|
x = 16807 * lo - 2836 * hi;
|
|
if (x < 0)
|
|
x += 0x7fffffff;
|
|
return ((*ctx = x) % ((u_long)RAND_MAX + 1));
|
|
#endif /* !USE_WEAK_SEEDING */
|
|
}
|
|
|
|
|
|
int
|
|
rand_r(unsigned int *ctx)
|
|
{
|
|
u_long val = (u_long) *ctx;
|
|
int r = do_rand(&val);
|
|
|
|
*ctx = (unsigned int) val;
|
|
return (r);
|
|
}
|
|
|
|
|
|
static u_long next = 1;
|
|
|
|
int
|
|
rand()
|
|
{
|
|
return (do_rand(&next));
|
|
}
|
|
|
|
void
|
|
srand(seed)
|
|
u_int seed;
|
|
{
|
|
next = seed;
|
|
}
|
|
|
|
|
|
/*
|
|
* sranddev:
|
|
*
|
|
* Many programs choose the seed value in a totally predictable manner.
|
|
* This often causes problems. We seed the generator using pseudo-random
|
|
* data from the kernel.
|
|
*/
|
|
void
|
|
sranddev()
|
|
{
|
|
int mib[2];
|
|
size_t len;
|
|
|
|
len = sizeof(next);
|
|
|
|
mib[0] = CTL_KERN;
|
|
mib[1] = KERN_ARND;
|
|
sysctl(mib, 2, (void *)&next, &len, NULL, 0);
|
|
}
|
|
|
|
|
|
#ifdef TEST
|
|
|
|
main()
|
|
{
|
|
int i;
|
|
unsigned myseed;
|
|
|
|
printf("seeding rand with 0x19610910: \n");
|
|
srand(0x19610910);
|
|
|
|
printf("generating three pseudo-random numbers:\n");
|
|
for (i = 0; i < 3; i++)
|
|
{
|
|
printf("next random number = %d\n", rand());
|
|
}
|
|
|
|
printf("generating the same sequence with rand_r:\n");
|
|
myseed = 0x19610910;
|
|
for (i = 0; i < 3; i++)
|
|
{
|
|
printf("next random number = %d\n", rand_r(&myseed));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
#endif /* TEST */
|
|
|