The Tor Browser / file revision

 function parseQuery(request, key) {

   var params = request.queryString.split('&');

   for (var j = 0; j < params.length; ++j) {

     var p = params[j];

 	if (p == key)

 	  return true;

     if (p.indexOf(key + "=") == 0)

 	  return p.substring(key.length + 1);

 	if (p.indexOf("=") < 0 && key == "")

 	  return p;

   }

   return false;

 }

 function handleRequest(request, response)

 {

   var referer = request.hasHeader("Referer") ? request.getHeader("Referer")

                                              : undefined; 

   if (referer == "http://mochi.test:8888/tests/content/media/test/test_referer.html") {

     var name = parseQuery(request, "name");

 	var type = parseQuery(request, "type");

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

                           getService(Components.interfaces.nsIProperties).

                           get("CurWorkD", Components.interfaces.nsILocalFile);

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

                           createInstance(Components.interfaces.nsIFileInputStream);

     var bis  = Components.classes["@mozilla.org/binaryinputstream;1"].

                           createInstance(Components.interfaces.nsIBinaryInputStream);

     var paths = "tests/content/media/test/" + name;

     var split = paths.split("/");

     for(var i = 0; i < split.length; ++i) {

       file.append(split[i]);

     }

     fis.init(file, -1, -1, false);

     bis.setInputStream(fis);

     var bytes = bis.readBytes(bis.available());

     response.setHeader("Content-Length", ""+bytes.length, false);

     response.setHeader("Content-Type", type, false);

     response.write(bytes, bytes.length);

     bis.close();

   }

   else {

     response.setStatusLine(request.httpVersion, 404, "Not found");

   }

 }