Improve registration_administer_registrations_access() function so one can check access for other accounts (not the current one)

The registration_administer_registrations_access() function is currently used as an access callback for a menu item. It checks whether the current user has access to a given registration.

I am in a position where I need to check programmatically if an account other than the current user has access to registration for a given entity.

Proposed solution

Here is a prosed solution which is backward-compatible. Change

/**
 * Access callback: for registration_registrations_page().
 *
 * Check if user has access to administer registrations for a host entity.
 *
 * @param string $entity_type
 *   The host entity type.
 * @param object $entity
 *   The host entity.
 *
 * @return bool
 *   Whether a user can view registrations for a host entity.
 *
 * @see registration_registrations_page()
 * @see registration_menu()
 */
function registration_administer_registrations_access($entity_type, $entity) {
  $registration_type = registration_get_entity_registration_type($entity_type, $entity);
  if ($registration_type) {
    if (user_access("administer $registration_type registration")) {
      return TRUE;
    }
    elseif (user_access("administer own $registration_type registration") && entity_access('update', $entity_type, $entity)) {
      return TRUE;
    }
  }
  return FALSE;
}

to

/**
 * Access callback: for registration_registrations_page().
 *
 * Check if user has access to administer registrations for a host entity.
 *
 * @param string $entity_type
 *   The host entity type.
 * @param object $entity
 *   The host entity.
 * @param object $account = NULL
 *   An account for which to check access. If NULL is provided the current
 *   user is used.
 *
 * @return bool
 *   Whether a user can view registrations for a host entity.
 *
 * @see registration_registrations_page()
 * @see registration_menu()
 */
function registration_administer_registrations_access($entity_type, $entity, $account = NULL) {
  $registration_type = registration_get_entity_registration_type($entity_type, $entity);
  if ($registration_type) {
    if (user_access("administer $registration_type registration", $account)) {
      return TRUE;
    }
    elseif (user_access("administer own $registration_type registration", $account) && entity_access('update', $entity_type, $entity, $account)) {
      return TRUE;
    }
  }
  return FALSE;
}