events: don't inherit from Object.prototype

This commit safely allows event names that are named the same as
properties that are ordinarily inherited from Object.prototype such
as __proto__.

Fixes: https://github.com/nodejs/node/issues/728
PR-URL: https://github.com/nodejs/node/pull/6092
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/test/parallel/test-event-emitter-special-event-names.js b/test/parallel/test-event-emitter-special-event-names.js
new file mode 100644
index 0000000000..fb3f1b52d9
--- /dev/null
+++ b/test/parallel/test-event-emitter-special-event-names.js
@@ -0,0 +1,36 @@
+'use strict';
+
+const common = require('../common');
+const EventEmitter = require('events');
+const assert = require('assert');
+
+const ee = new EventEmitter();
+const handler = () => {};
+
+assert.strictEqual(ee._events.hasOwnProperty, undefined);
+assert.strictEqual(ee._events.toString, undefined);
+
+ee.on('__proto__', handler);
+ee.on('__defineGetter__', handler);
+ee.on('toString', handler);
+
+assert.deepStrictEqual(ee.eventNames(), [
+  '__proto__',
+  '__defineGetter__',
+  'toString'
+]);
+
+assert.deepStrictEqual(ee.listeners('__proto__'), [handler]);
+assert.deepStrictEqual(ee.listeners('__defineGetter__'), [handler]);
+assert.deepStrictEqual(ee.listeners('toString'), [handler]);
+
+ee.on('__proto__', common.mustCall(function(val) {
+  assert.strictEqual(val, 1);
+}));
+ee.emit('__proto__', 1);
+
+process.on('__proto__', common.mustCall(function(val) {
+  assert.strictEqual(val, 1);
+}));
+process.emit('__proto__', 1);
+