```
/**
 * Farm info API callback.
 */
function farm_api_info() {
  global $base_url, $conf, $user;
  $info = array(
    'name' => $conf['site_name'],
    'url' => $base_url,
    'api_version' => FARM_API_VERSION,
  );
  if (!empty($user->uid)) {
    $info['user'] = array(
      'uid' => $user->uid,
      'name' => $user->name,
      'mail' => $user->mail,
    );
  }
  drupal_json_output($info);
}
```