The Tor Browser / file revision

 function getInputStream(path)

 {

   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 split = path.split("/");

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

     file.append(split[i]);

   }

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

   return fis;

 }

 function handleRequest(request, response)

 {

   var inputStream = getInputStream("tests/content/base/test/bug638112-response.txt")

   response.seizePower();

   response.bodyOutputStream.writeFrom(inputStream,

                                       inputStream.available());

   response.finish();

   inputStream.close();

 }