gecko-dev/image/test/mochitest/bug490949.sjs

function handleRequest(request, response)
{
  var file = Components.classes["@mozilla.org/file/directory_service;1"]
             .getService(Components.interfaces.nsIProperties)
             .get("CurWorkD", Components.interfaces.nsIFile);

  file.append("tests");
  file.append("image");
  file.append("test");
  file.append("mochitest");

  var redirectstate = "/image/test/mochitest/bug490949.sjs";
  if (getState(redirectstate) == "") {
    file.append('blue.png');
    setState(redirectstate, "red");
  } else {
    file.append('red.png');
    setState(redirectstate, "");
  }
  response.setHeader("Cache-Control", "no-cache", false);

  var fileStream = Components.classes['@mozilla.org/network/file-input-stream;1']
                   .createInstance(Components.interfaces.nsIFileInputStream);
  fileStream.init(file, 1, 0, false);
  var binaryStream = Components.classes['@mozilla.org/binaryinputstream;1']
                     .createInstance(Components.interfaces.nsIBinaryInputStream);
  binaryStream.setInputStream(fileStream);

  response.bodyOutputStream.writeFrom(binaryStream, binaryStream.available());

  binaryStream.close();
  fileStream.close();
}