1 /* Copyright (C) 1992-2022 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Lesser General Public 6 License as published by the Free Software Foundation; either 7 version 2.1 of the License, or (at your option) any later version. 8 9 The GNU C Library is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, see 16 <https://www.gnu.org/licenses/>. */ 17 18 #include <string.h> 19 #include <stdlib.h> 20 #include <random-bits.h> 21 #include <unistd.h> 22 23 char * strfry(char * string)24strfry (char *string) 25 { 26 static int init; 27 static struct random_data rdata; 28 29 if (!init) 30 { 31 static char state[32]; 32 rdata.state = NULL; 33 __initstate_r (random_bits (), 34 state, sizeof (state), &rdata); 35 init = 1; 36 } 37 38 size_t len = strlen (string); 39 if (len > 0) 40 for (size_t i = 0; i < len - 1; ++i) 41 { 42 int32_t j; 43 __random_r (&rdata, &j); 44 j = j % (len - i) + i; 45 46 char c = string[i]; 47 string[i] = string[j]; 48 string[j] = c; 49 } 50 51 return string; 52 } 53