The Tor Browser / file revision

 function getFileStream(filename)

 {

   // Get the location of this sjs file, and then use that to figure out where

   // to find where our other files are.

   var self = Components.classes["@mozilla.org/file/local;1"]

                        .createInstance(Components.interfaces.nsILocalFile);

   self.initWithPath(getState("__LOCATION__"));

   var file = self.parent;

   file.append(filename);

   dump(file.path + "\n");

   var fileStream = Components.classes['@mozilla.org/network/file-input-stream;1']

                      .createInstance(Components.interfaces.nsIFileInputStream);

   fileStream.init(file, 1, 0, false);

   return fileStream;

 }

 var gTimer;

 function handleRequest(request, response)

 {

   response.processAsync();

   response.setStatusLine(request.httpVersion, 200, "OK");

   response.setHeader("Content-Type", "image/gif", false);

   var firststream = getFileStream("threeframes-start.gif");

   response.bodyOutputStream.writeFrom(firststream, firststream.available())

   firststream.close();

   gTimer = Components.classes["@mozilla.org/timer;1"].createInstance(Components.interfaces.nsITimer);

   gTimer.initWithCallback(function()

   {

     var secondstream = getFileStream("threeframes-end.gif");

     response.bodyOutputStream.writeFrom(secondstream, secondstream.available())

     secondstream.close();

     response.finish();

     // This time needs to be longer than the animation timer in

     // threeframes-start.gif. That's specified as 100ms; just use 5 seconds as

     // a reasonable upper bound. Since this is just a crashtest, timeouts

     // aren't a big deal.

   }, 5 * 1000 /* milliseconds */, Components.interfaces.nsITimer.TYPE_ONE_SHOT);

 }