Blame string/strfry.c

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/* Copyright (C) 1992-2018 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <http://www.gnu.org/licenses/>.  */
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#include <string.h>
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#include <stdlib.h>
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#include <time.h>
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#include <unistd.h>
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char *
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strfry (char *string)
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{
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  static int init;
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  static struct random_data rdata;
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  if (!init)
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    {
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      static char state[32];
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      rdata.state = NULL;
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      __initstate_r (time ((time_t *) NULL) ^ getpid (),
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		     state, sizeof (state), &rdata);
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      init = 1;
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    }
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  size_t len = strlen (string);
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  if (len > 0)
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    for (size_t i = 0; i < len - 1; ++i)
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      {
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	int32_t j;
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	__random_r (&rdata, &j);
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	j = j % (len - i) + i;
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	char c = string[i];
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	string[i] = string[j];
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	string[j] = c;
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      }
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  return string;
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}