glibc/string/strfry.c

54 lines
1.5 KiB
C

/* Copyright (C) 1992, 1996, 1999, 2002, 2007 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
char *
strfry (char *string)
{
static int init;
static struct random_data rdata;
size_t len, i;
if (!init)
{
static char state[32];
rdata.state = NULL;
__initstate_r (time ((time_t *) NULL) ^ getpid (),
state, sizeof (state), &rdata);
init = 1;
}
len = strlen (string) - 1;
for (i = 0; i < len; ++i)
{
int32_t j;
__random_r (&rdata, &j);
j = j % (len - i) + i;
char c = string[i];
string[i] = string[j];
string[j] = c;
}
return string;
}