Club Drupal

  $form['file_entity_max_filesize_extensions'] = array(

    '#type' => 'textarea',

    '#title' => t('Maximum upload size per extension'),

    '#default_value' => variable_get('file_entity_max_filesize_extensions', ''),

    '#description' => t('Set the maximum filesize for specific extensions. Enter one value per line, in the format <strong>extension|filesize</strong>. When an extension does not have a file size limit, the default maximum file size is used.'),

    '#rows' => 10,

    '#element_validate' => array('file_entity_max_filesize_extensions_validate'),

  );

/**

 * Element validate callback for the maximum upload size / file extension field.

 */

function file_entity_max_filesize_extensions_validate($element, &$form_state) {

  $list = explode("\n", $element['#value']);

  foreach ($list as $position => $text) {

    $matches = array();

    preg_match('/(.*)\|(.*)/', $text, $matches);

    $extension = $matches[1];

    $filesize = $matches[2];

    //Validate filesize.

    $element['#value'] = $filesize;

    _file_generic_settings_max_filesize($element, $form_state);

    //Validate extension.

    $extensions = explode(' ', $form_state['input']['file_entity_default_allowed_extensions']);

    if (!in_array($extension, $extensions)) {

      form_error($element, t('"!extension" was not found in the list of allowed extensions.', array('!extension' => $extension)));

    }

  }

}