wtf/RandomNumberSeed.h

   1 /*
   2  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef WTF_RandomNumberSeed_h
  27 #define WTF_RandomNumberSeed_h
  28
  29 #include <stdlib.h>
  30 #include <time.h>
  31
  32 #if HAVE(SYS_TIME_H)
  33 #include <sys/time.h>
  34 #endif
  35
  36 #if PLATFORM(UNIX)
  37 #include <sys/types.h>
  38 #include <unistd.h>
  39 #endif
  40
  41 // Internal JavaScriptCore usage only
  42 namespace WTF {
  43
  44 inline void initializeRandomNumberGenerator()
  45 {
  46 #if PLATFORM(DARWIN)
  47     // On Darwin we use arc4random which initialises itself.
  48 #elif COMPILER(MSVC) && defined(_CRT_RAND_S)
  49     // On Windows we use rand_s which intialises itself
  50 #elif PLATFORM(UNIX)
  51     // srandomdev is not guaranteed to exist on linux so we use this poor seed, this should be improved
  52     timeval time;
  53     gettimeofday(&time, 0);
  54     srandom(static_cast<unsigned>(time.tv_usec * getpid()));
  55 #else
  56     srand(static_cast<unsigned>(time(0)));
  57 #endif
  58 }
  59
  60 inline void initializeWeakRandomNumberGenerator()
  61 {
  62 #if COMPILER(MSVC) && defined(_CRT_RAND_S)
  63     // We need to initialise windows rand() explicitly for Math.random
  64     unsigned seed = 0;
  65     rand_s(&seed);
  66     srand(seed);
  67 #endif
  68 }
  69 }
  70
  71 #endif