From 79a8cd0dec63f9da7b829cafcaaeb4428d86ec7a Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Sun, 2 Jun 2019 20:24:22 +0200
Subject: [PATCH] worker: add typechecking for postMessage transfer list

If the transfer list argument is present, it should be an array.
This commit adds typechecking to that effect. This aligns behaviour
with browsers.

PR-URL: https://github.com/nodejs/node/pull/28033
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
---
 src/node_messaging.cc                     |  9 +++++++++
 test/parallel/test-worker-message-port.js | 21 +++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/node_messaging.cc b/src/node_messaging.cc
index ba39d01dc3b992..79fa510ed70ab1 100644
--- a/src/node_messaging.cc
+++ b/src/node_messaging.cc
@@ -714,6 +714,15 @@ void MessagePort::PostMessage(const FunctionCallbackInfo<Value>& args) {
     return THROW_ERR_MISSING_ARGS(env, "Not enough arguments to "
                                        "MessagePort.postMessage");
   }
+  if (!args[1]->IsNullOrUndefined() && !args[1]->IsObject()) {
+    // Browsers ignore null or undefined, and otherwise accept an array or an
+    // options object.
+    // TODO(addaleax): Add support for an options object and generic sequence
+    // support.
+    // Refs: https://github.com/nodejs/node/pull/28033#discussion_r289964991
+    return THROW_ERR_INVALID_ARG_TYPE(env,
+        "Optional transferList argument must be an array");
+  }
 
   MessagePort* port = Unwrap<MessagePort>(args.This());
   // Even if the backing MessagePort object has already been deleted, we still
diff --git a/test/parallel/test-worker-message-port.js b/test/parallel/test-worker-message-port.js
index dce9da0b3063f5..d1c58216fd9d00 100644
--- a/test/parallel/test-worker-message-port.js
+++ b/test/parallel/test-worker-message-port.js
@@ -70,6 +70,27 @@ const { MessageChannel, MessagePort } = require('worker_threads');
   });
 }
 
+{
+  const { port1, port2 } = new MessageChannel();
+  port2.on('message', common.mustCall(4));
+  port1.postMessage(1, null);
+  port1.postMessage(2, undefined);
+  port1.postMessage(3, []);
+  port1.postMessage(4, {});
+
+  const err = {
+    constructor: TypeError,
+    code: 'ERR_INVALID_ARG_TYPE',
+    message: 'Optional transferList argument must be an array'
+  };
+
+  assert.throws(() => port1.postMessage(5, 0), err);
+  assert.throws(() => port1.postMessage(5, false), err);
+  assert.throws(() => port1.postMessage(5, 'X'), err);
+  assert.throws(() => port1.postMessage(5, Symbol('X')), err);
+  port1.close();
+}
+
 {
   assert.deepStrictEqual(
     Object.getOwnPropertyNames(MessagePort.prototype).sort(),