Method test

/**
 * Method to test if the file path is valid
 *
 * @param   \SimpleXMLElement  $element  The SimpleXMLElement object representing the `<field>` tag for the form field object.
 * @param   mixed              $value    The form field value to validate.
 * @param   string             $group    The field name group control value. This acts as an array container for the field.
 *                                       For example if the field has name="foo" and the group value is set to "bar" then the
 *                                       full field name would end up being "bar[foo]".
 * @param   Registry           $input    An optional Registry object with the entire data set to validate against the entire form.
 * @param   Form               $form     The form object for which the field is being tested.
 *
 * @return  boolean  True if the value is valid, false otherwise.
 *
 * @since   3.9.21
 */
public function test(\SimpleXMLElement $element, $value, $group = null, Registry $input = null, Form $form = null)
{
    $value = trim($value);
    // If the field is empty and not required, the field is valid.
    $required = (string) $element['required'] == 'true' || (string) $element['required'] == 'required';
    if (!$required && empty($value)) {
        return true;
    }
    // Get the exclude setting from the xml
    $exclude = (array) explode('|', (string) $element['exclude']);
    // Exclude current folder '.' to be safe from full path disclosure
    $exclude[] = '.';
    // Check the exclude setting
    $path = preg_split('/[\\/\\\\]/', $value);
    if (in_array(strtolower($path[0]), $exclude) || empty($path[0])) {
        return false;
    }
    // Prepend the root path
    $value = JPATH_ROOT . '/' . $value;
    // Check if $value is a valid path, which includes not allowing to break out of the current path
    try {
        Path::check($value);
    } catch (\Exception $e) {
        // When there is an exception in the check path this is not valid
        return false;
    }
    // When there are no exception this rule should pass.
    // See: https://github.com/joomla/joomla-cms/issues/30500#issuecomment-683290162
    return true;
}