kdecore/util/krandom.cpp

   1 /* This file is part of the KDE libraries
   2     Copyright (c) 1999 Matthias Kalle Dalheimer <kalle@kde.org>
   3     Copyright (c) 2000 Charles Samuels <charles@kde.org>
   4     Copyright (c) 2005 Joseph Wenninger <kde@jowenn.at>
   5
   6     This library is free software; you can redistribute it and/or
   7     modify it under the terms of the GNU Library General Public
   8     License as published by the Free Software Foundation; either
   9     version 2 of the License, or (at your option) any later version.
  10
  11     This library is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14     Library General Public License for more details.
  15
  16     You should have received a copy of the GNU Library General Public License
  17     along with this library; see the file COPYING.LIB.  If not, write to
  18     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19     Boston, MA 02110-1301, USA.
  20         */
  21
  22 #include "krandom.h"
  23
  24 #include <stdlib.h>
  25 #include <unistd.h>
  26 #include <stdio.h>
  27 #include <time.h>
  28 #include <sys/time.h>
  29 #include <fcntl.h>
  30 #include <kde_file.h>
  31
  32 int KRandom::random()
  33 {
  34    static bool init = false;
  35    if (!init)
  36    {
  37       unsigned int seed;
  38       init = true;
  39       int fd = KDE_open("/dev/urandom", O_RDONLY);
  40       if (fd < 0 || ::read(fd, &seed, sizeof(seed)) != sizeof(seed))
  41       {
  42             // No /dev/urandom... try something else.
  43             srand(getpid());
  44             seed = rand()+time(0);
  45       }
  46       if (fd >= 0) close(fd);
  47       srand(seed);
  48    }
  49    return rand();
  50 }
  51
  52 QString KRandom::randomString(int length)
  53 {
  54    if (length <=0 ) return QString();
  55
  56    QString str; str.resize( length );
  57    int i = 0;
  58    while (length--)
  59    {
  60       int r=random() % 62;
  61       r+=48;
  62       if (r>57) r+=7;
  63       if (r>90) r+=6;
  64       str[i++] =  char(r);
  65       // so what if I work backwards?
  66    }
  67    return str;
  68 }