draw.php save invoker

<?php

$x = intval($_REQUEST['x']);
$y = intval($_REQUEST['y']);

if ($_REQUEST['submit']) {
  // extract data from post and save it to a file
  $data = $_POST['data'];
  $key = "$x,$y";
  $filename = "tmp/" . $key . '-' . rand()%100;
  file_put_contents($filename, json_encode($data));

  // run save.py
  $result = trim(shell_exec("python save.py '$x' '$y' '$filename' 2>&1"));
  if ($result != 1) {
    die("Error saving. $result<HR>");
  }

  print "<script>window.location = 'index.php';</script>";
  return;
}

$time = time();
print <<<EOF

//...