From b0f1420e24d582f09e23eaa4361e79507fbcac6f Mon Sep 17 00:00:00 2001
From: Ben Kelly <ben@wanderview.com>
Date: Fri, 11 Dec 2015 14:53:11 -0500
Subject: [PATCH] Bug 1226443 P6 Ignore update() called during top level
 service worker script evaluation. r=ehsan

---
 dom/workers/ServiceWorkerRegistration.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/dom/workers/ServiceWorkerRegistration.cpp b/dom/workers/ServiceWorkerRegistration.cpp
index 21bb739e309..e26215c38ef 100644
--- a/dom/workers/ServiceWorkerRegistration.cpp
+++ b/dom/workers/ServiceWorkerRegistration.cpp
@@ -1000,6 +1000,14 @@ ServiceWorkerRegistrationWorkerThread::Update(ErrorResult& aRv)
     return nullptr;
   }
 
+  // Avoid infinite update loops by ignoring update() calls during top
+  // level script evaluation.  See:
+  // https://github.com/slightlyoff/ServiceWorker/issues/800
+  if (worker->LoadScriptAsPartOfLoadingServiceWorkerScript()) {
+    promise->MaybeResolve(JS::UndefinedHandleValue);
+    return promise.forget();
+  }
+
   RefPtr<PromiseWorkerProxy> proxy = PromiseWorkerProxy::Create(worker, promise);
   if (!proxy) {
     aRv.Throw(NS_ERROR_DOM_ABORT_ERR);