test.php

<?php

guesstimate_file_location($boltforms_location, $public_location) {

  $tested = false;
  $formfilename = $boltforms_location . '/testfile.txt';
  $publicfilename = $public_location . '/testfile.txt';
  $timestamp = microtime();
  
  if(file_put_contents ( $formfilename , $timestamp )) {
    $tested = file_get_contents ( $publicfilename );
  }

  if ($tested == $timestamp) {
    return true;
  }
  return false;
}

test2.php

<?php

guesstimate_by_realpath($formlocation, $filelocation) {
  if(realpath($formlocation) == realpath($filelocation)) {
    return true;
  }
  return false;
}