Drupal 7 Module Development

Chapter 8
if (!flood_is_allowed('contact', $limit, $window) &&
!user_access('administer contact forms')) {
drupal_set_message(t("You cannot send more than %limit messages
in @interval. Please try again later.", array('%limit' => $limit, '@
interval' => format_interval($window))), 'error');
drupal_access_denied();
drupal_exit();
}
The preceding code stops all processing of the contact form page if the user is
suspected of spamming the form. If the user violates the threshold of allowed
messages per hour, a warning message is delivered and the Access denied
page is rendered.
Note the use of drupal_exit() here to stop the rest of the page execution. Since this
access denied message is performed during form definition, drupal_exit() must be
invoked to stop the rest of the rendering process.
Note: Do not call the normal PHP exit() function from within Drupal
code. Doing so may stop the execution of internal functions (such as
session handling) or API hooks. The drupal_exit() function is
provided to safely stop the execution of a Drupal request.
Within a normal page context, however, we should return the constant
MENU_ACCESS_DENIED instead of drupal_exit(). We might do this instead
of using a custom menu callback. Returning to our earlier example:
/**
* Implement hook_menu().
*/
function example_menu() {
$items['user/%user/content'] = array(
'title' => 'Content creation',
'page callback' => 'example_user_page',
'page arguments' => array(1),
'access arguments' => array('view content creation permissions'),
'type' => MENU_LOCAL_TASK,
);
return $items;
}
/**
* Custom page callback for a user tab.
*/
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