process: ensure that the "exit" event always has "code" given

Upon "normal" exiting of Node (i.e. the event loop completes naturally),
the "code" parameter was not being passed to the "exit" event listeners.

Be consistent. Tests included.

src/node.cc

@@ -2775,9 +2775,9 @@ void EmitExit(v8::Handle<v8::Object> process_l) {
   Local<Value> emit_v = process_l->Get(String::New("emit"));
   assert(emit_v->IsFunction());
   Local<Function> emit = Local<Function>::Cast(emit_v);
-  Local<Value> args[] = { String::New("exit") };
+  Local<Value> args[] = { String::New("exit"), Integer::New(0) };
   TryCatch try_catch;
-  emit->Call(process_l, 1, args);
+  emit->Call(process_l, 2, args);
   if (try_catch.HasCaught()) {
     FatalException(try_catch);
   }

test/simple/test-process-exit-recursive.js

@@ -0,0 +1,35 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var assert = require('assert');
+
+// recursively calling .exit() should not overflow the call stack
+var nexits = 0;
+
+process.on('exit', function(code) {
+  assert.equal(nexits++, 0);
+  assert.equal(code, 1);
+
+  // now override the exit code of 1 with 0 so that the test passes
+  process.exit();
+});
+
+process.exit(1);

test/simple/test-process-exit.js

@@ -22,12 +22,13 @@
 var common = require('../common');
 var assert = require('assert');
 
-// recursively calling .exit() should not overflow the call stack
+// calling .exit() from within "exit" should not overflow the call stack
 var nexits = 0;
 
-process.on('exit', function() {
+process.on('exit', function(code) {
   assert.equal(nexits++, 0);
+  assert.equal(code, 0);
   process.exit();
 });
 
-process.exit();
+// "exit" should be emitted unprovoked