Revision f230a1cf deps/v8/src/utils/random-number-generator.cc

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deps/v8/src/utils/random-number-generator.cc
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#include "utils/random-number-generator.h"
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#include <cstdio>


  		




  
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#include <cstdlib>


  		




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#include "flags.h"


  		




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#include "platform/mutex.h"


  		




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    }


  		




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  }


  		




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#if V8_OS_CYGWIN || V8_OS_WIN


  		




  
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  // Use rand_s() to gather entropy on Windows. See:


  		




  
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  // https://code.google.com/p/v8/issues/detail?id=2905


  		




  
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  unsigned first_half, second_half;


  		




  
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  errno_t result = rand_s(&first_half);


  		




  
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  ASSERT_EQ(0, result);


  		




  
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  result = rand_s(&second_half);


  		




  
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  ASSERT_EQ(0, result);


  		




  
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  SetSeed((static_cast<int64_t>(first_half) << 32) + second_half);


  		




  
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#else


  		




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  // Gather entropy from /dev/urandom if available.


  		




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  FILE* fp = fopen("/dev/urandom", "rb");


  		




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  if (fp != NULL) {


  		




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  // We cannot assume that random() or rand() were seeded


  		




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  // properly, so instead of relying on random() or rand(),


  		




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  // we just seed our PRNG using timing data as fallback.


  		




  
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  // This is weak entropy, but it's sufficient, because


  		




  
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  // it is the responsibility of the embedder to install


  		




  
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  // an entropy source using v8::V8::SetEntropySource(),


  		




  
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  // which provides reasonable entropy, see:


  		




  
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  // https://code.google.com/p/v8/issues/detail?id=2905


  		




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  int64_t seed = Time::NowFromSystemTime().ToInternalValue() << 24;


  		




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  seed ^= TimeTicks::HighResNow().ToInternalValue() << 16;


  		




  
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  seed ^= TimeTicks::HighResolutionNow().ToInternalValue() << 16;


  		




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  seed ^= TimeTicks::Now().ToInternalValue() << 8;


  		




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  SetSeed(seed);


  		




  
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#endif  // V8_OS_CYGWIN || V8_OS_WIN


  		




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}


  		




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