Introduce a random entropy source which can optionally be provided at initialization.

src/v8.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 32 matching lines @@
 
 static Mutex* init_once_mutex = OS::CreateMutex();
 static bool init_once_called = false;
 
 bool V8::is_running_ = false;
 bool V8::has_been_setup_ = false;
 bool V8::has_been_disposed_ = false;
 bool V8::has_fatal_error_ = false;
 bool V8::use_crankshaft_ = true;
 
+static Mutex* entropy_mutex = OS::CreateMutex();
+static EntropySource entropy_source;
+
 
 bool V8::Initialize(Deserializer* des) {
   InitializeOncePerProcess();
 
   // The current thread may not yet had entered an isolate to run.
   // Note the Isolate::Current() may be non-null because for various
   // initialization purposes an initializing thread may be assigned an isolate
   // but not actually enter it.
   if (i::Isolate::CurrentPerIsolateThreadData() == NULL) {
     i::Isolate::EnterDefaultIsolate();
@@ skipping 32 matching lines @@
   if (!has_been_setup_ || has_been_disposed_) return;
   isolate->TearDown();
 
   is_running_ = false;
   has_been_disposed_ = true;
 }
 
 
 static void seed_random(uint32_t* state) {
   for (int i = 0; i < 2; ++i) {
-    state[i] = FLAG_random_seed;
-    while (state[i] == 0) {
+    if (FLAG_random_seed != NULL)

[Mads Ager (chromium), 2011/07/17 09:11:39]

Please consistently use braces around the body. Also, FLAG_random_seem is not a
pointer but an int, so the test should be '0' instead of 'NULL'. I'll fix these
too.

+      state[i] = FLAG_random_seed;
+    else if (entropy_source != NULL) {
+      uint32_t val;
+      ScopedLock lock(entropy_mutex);
+      entropy_source(reinterpret_cast<unsigned char*>(&val), sizeof(uint32_t));
+      state[i] = val;
+    } else {
       state[i] = random();
     }
   }
 }
 
 
 // Random number generator using George Marsaglia's MWC algorithm.
 static uint32_t random_base(uint32_t* state) {
   // Initialize seed using the system random().
   // No non-zero seed will ever become zero again.
   if (state[0] == 0) seed_random(state);
 
   // Mix the bits.  Never replaces state[i] with 0 if it is nonzero.
   state[0] = 18273 * (state[0] & 0xFFFF) + (state[0] >> 16);
   state[1] = 36969 * (state[1] & 0xFFFF) + (state[1] >> 16);
 
   return (state[0] << 14) + (state[1] & 0x3FFFF);
 }
 
 
+void V8::SetEntropySource(EntropySource source) {
+  entropy_source = source;
+}
+
+
 // Used by JavaScript APIs
 uint32_t V8::Random(Isolate* isolate) {
   ASSERT(isolate == Isolate::Current());
   return random_base(isolate->random_seed());
 }
 
 
 // Used internally by the JIT and memory allocator for security
 // purposes. So, we keep a different state to prevent informations
 // leaks that could be used in an exploit.
@@ skipping 57 matching lines @@
     use_crankshaft_ = false;
   }
 
   RuntimeProfiler::GlobalSetup();
 
   // Peephole optimization might interfere with deoptimization.
   FLAG_peephole_optimization = !use_crankshaft_;
 }
 
 } }  // namespace v8::internal