Let SetEntropySource() fail if called after V8::Initialize().

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 9756874f6978bb229a0980454a120d8deb75a62c..e3cde52e168f4cc7a7d512945413eb121499fb2e 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -5175,6 +5175,13 @@ bool v8::V8::Initialize() {
 
 
 void v8::V8::SetEntropySource(EntropySource entropy_source) {
+  // The entropy source must be set before the library is initialized,
+  // as otherwise not all random number generators will pick up the
+  // entropy source and will fall back to weak entropy instead.
+  i::Isolate* isolate = i::Isolate::UncheckedCurrent();

[Michael Starzinger, 2013/09/23 14:51:31]

We try to get rid of Isolate::Current, please try not to add new call-site to
this function.

[Benedikt Meurer, 2013/09/23 20:25:51]

I know, but there's currently no other way to perform this check. We're planning
to add one, but that'll take some more cleanup time.

+  ApiCheck(isolate != NULL && isolate->IsInitialized(),
+           "v8::V8::SetEntropySource",
+           "Cannot set entropy source once V8 is initialized.");
   i::RandomNumberGenerator::SetEntropySource(entropy_source);
 }