Implement process "uncaughtException" event

This event can be used to overwrite the default exception mechanism which
reports the exception and kills the node process.

See google group post:
http://groups.google.com/group/nodejs/browse_thread/thread/9721dc3a2638446f

src/node.cc

@@ -524,9 +524,51 @@ static void OnFatalError(const char* location, const char* message) {
   exit(1);
 }
 
+static int uncaught_exception_counter = 0;
+
 void FatalException(TryCatch &try_catch) {
-  ReportException(&try_catch);
+  HandleScope scope;
-  exit(1);
+
+  // Check if uncaught_exception_counter indicates a recursion
+  if (uncaught_exception_counter > 0) {
+    ReportException(&try_catch);
+    exit(1);
+  }
+
+  Local<Value> listeners_v = process->Get(String::NewSymbol("listeners"));
+  assert(listeners_v->IsFunction());
+
+  Local<Function> listeners = Local<Function>::Cast(listeners_v);
+
+  Local<String> uncaught_exception = String::NewSymbol("uncaughtException");
+
+  Local<Value> argv[1] = { uncaught_exception };
+  Local<Value> ret = listeners->Call(process, 1, argv);
+
+  assert(ret->IsArray());
+
+  Local<Array> listener_array = Local<Array>::Cast(ret);
+
+  uint32_t length = listener_array->Length();
+  // Report and exit if process has no "uncaughtException" listener
+  if (length == 0) {
+    ReportException(&try_catch);
+    exit(1);
+  }
+
+  // Otherwise fire the process "uncaughtException" event
+  Local<Value> emit_v = process->Get(String::NewSymbol("emit"));
+  assert(emit_v->IsFunction());
+
+  Local<Function> emit = Local<Function>::Cast(emit_v);
+
+  Local<Value> error = try_catch.Exception();
+  Local<Value> event_argv[2] = { uncaught_exception, error };
+
+  uncaught_exception_counter++;
+  emit->Call(process, 2, event_argv);
+  // Decrement so we know if the next exception is a recursion or not
+  uncaught_exception_counter--;
 }
 
 static ev_async eio_watcher;

src/node.js

@@ -677,6 +677,5 @@ if (process.ARGV[1].charAt(0) != "/" && !/^http:\/\//.exec(process.ARGV[1])) {
 process.mainModule = createModule(".");
 var loadPromise = new process.Promise();
 process.mainModule.load(process.ARGV[1], loadPromise);
-loadPromise.wait();
 
 }()); // end annonymous namespace

test/mjsunit/test-exception-handler.js

@@ -0,0 +1,25 @@
+process.mixin(require("./common"));
+
+var MESSAGE = 'catch me if you can';
+var caughtException = false;
+
+process.addListener('uncaughtException', function (e) {
+  puts("uncaught exception! 1");
+  assertEquals(MESSAGE, e.message);
+  caughtException = true;
+});
+
+process.addListener('uncaughtException', function (e) {
+  puts("uncaught exception! 2");
+  assertEquals(MESSAGE, e.message);
+  caughtException = true;
+});
+
+setTimeout(function() {
+  throw new Error(MESSAGE);
+}, 10);
+
+process.addListener("exit", function () {
+  puts("exit");
+  assertTrue(caughtException);
+});