Question

I’m writing a nodejs C++ module and inside of my init function I have make a system call that may fail. On failing I want it to throw an exception to the interpreter to deal with but instead a get a seg-fault. How do I get the correct behavior?

so for example I have something similar to:

//...
void Init(Handle<Object> target) {
  if (my_setup_io()==FAIL_CODITION){
    ThrowException(Exception::Error(
      String::New("Could not init ")));  //SEG fault instead of exception
  }
  target->Set(String::NewSymbol("myFunction"),
      FunctionTemplate::New(myFunction)->GetFunction());
 }

NODE_MODULE(example, Init)

Answer 1

The main issue is ThrowException triggers an exception in JS, but it does not actually trigger a C++ exception. That means that your code will attempt to run Set after the exception runs.

It should work fine if you return after scheduling the JS throw.

void Init(Handle<Object> target) {
  if (my_setup_io()==FAIL_CODITION){
    ThrowException(Exception::Error(String::New("Could not init ")));
    return; // RETURN!
  }
  target->Set(String::NewSymbol("myFunction"),
    FunctionTemplate::New(myFunction)->GetFunction());
}

NODE_MODULE(example, Init)