The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

  * You can obtain one at http://mozilla.org/MPL/2.0/. */

 importScripts("resource://gre/modules/osfile.jsm");

 function log(message) {

   dump("WebManagerWorker " + message + "\n");

 }

 onmessage = function(event) {

   let { url, path } = event.data;

   let file = OS.File.open(path, { truncate: true });

   let request = new XMLHttpRequest({ mozSystem: true });

   request.open("GET", url, true);

   request.responseType = "moz-chunked-arraybuffer";

   request.onprogress = function(event) {

     log("onprogress: received " + request.response.byteLength + " bytes");

     let bytesWritten = file.write(new Uint8Array(request.response));

     log("onprogress: wrote " + bytesWritten + " bytes");

   };

   request.onreadystatechange = function(event) {

     log("onreadystatechange: " + request.readyState);

     if (request.readyState !== 4) {

       return;

     }

     file.close();

     if (request.status === 200) {

       postMessage({ type: "success" });

     } else {

       try {

         OS.File.remove(path);

       } catch(ex) {

         log("error removing " + path + ": " + ex);

       }

       let statusMessage = request.status + " - " + request.statusText;

       postMessage({ type: "failure", message: statusMessage });

     }

   };

   request.send(null);

 }