From c8996f654fa8c1c8100e84ba387d0dabb9b0d598 Mon Sep 17 00:00:00 2001
From: Rob Wu <rob@robwu.nl>
Date: Fri, 25 Dec 2015 13:24:19 +0100
Subject: [PATCH] Detect and handle premature worker load error

Fall back to a fake worker if the worker fails to load or initialize,
e.g. due to a network error, a security error or simply a script error.
---
 src/display/api.js | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/src/display/api.js b/src/display/api.js
index 6aa315644..4f40c49f8 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -1302,11 +1302,32 @@ var PDFWorker = (function PDFWorkerClosure() {
           // https://bugzilla.mozilla.org/show_bug.cgi?id=683280
           var worker = new Worker(workerSrc);
           var messageHandler = new MessageHandler('main', 'worker', worker);
-          messageHandler.on('test', function PDFWorker_test(data) {
+          var terminateEarly = function() {
+            worker.removeEventListener('error', onWorkerError);
+            messageHandler.destroy();
+            worker.terminate();
             if (this.destroyed) {
               this._readyCapability.reject(new Error('Worker was destroyed'));
-              messageHandler.destroy();
-              worker.terminate();
+            } else {
+              // Fall back to fake worker if the termination is caused by an
+              // error (e.g. NetworkError / SecurityError).
+              this._setupFakeWorker();
+            }
+          }.bind(this);
+
+          var onWorkerError = function(event) {
+            if (!this._webWorker) {
+              // Worker failed to initialize due to an error. Clean up and fall
+              // back to the fake worker.
+              terminateEarly();
+            }
+          }.bind(this);
+          worker.addEventListener('error', onWorkerError);
+
+          messageHandler.on('test', function PDFWorker_test(data) {
+            worker.removeEventListener('error', onWorkerError);
+            if (this.destroyed) {
+              terminateEarly();
               return; // worker was destroyed
             }
             var supportTypedArray = data && data.supportTypedArray;
@@ -1333,10 +1354,9 @@ var PDFWorker = (function PDFWorkerClosure() {
           });
 
           messageHandler.on('ready', function (data) {
+            worker.removeEventListener('error', onWorkerError);
             if (this.destroyed) {
-              this._readyCapability.reject(new Error('Worker was destroyed'));
-              messageHandler.destroy();
-              worker.terminate();
+              terminateEarly();
               return; // worker was destroyed
             }
             try {