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<?php
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// $Id$
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/**
 * @file
 * Common functions that many Drupal modules will need to reference.
 *
 * The functions that are critical and need to be available even when serving
 * a cached page are instead located in bootstrap.inc.
 */

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/**
 * @defgroup php_wrappers PHP wrapper functions
 * @{
 * Functions that are wrappers or custom implementations of PHP functions.
 *
 * Certain PHP functions should not be used in Drupal. Instead, Drupal's
 * replacement functions should be used.
 *
 * For example, for improved or more secure UTF8-handling, or RFC-compliant
 * handling of URLs in Drupal.
 *
 * For ease of use and memorizing, all these wrapper functions use the same name
 * as the original PHP function, but prefixed with "drupal_". Beware, however,
 * that not all wrapper functions support the same arguments as the original
 * functions.
 *
 * You should always use these wrapper functions in your code.
 *
 * Wrong:
 * @code
 *   $my_substring = substr($original_string, 0, 5);
 * @endcode
 *
 * Correct:
 * @code
 *   $my_substring = drupal_substr($original_string, 0, 5);
 * @endcode
 *
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 * @}
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 */

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/**
 * Return status for saving which involved creating a new item.
 */
define('SAVED_NEW', 1);

/**
 * Return status for saving which involved an update to an existing item.
 */
define('SAVED_UPDATED', 2);

/**
 * Return status for saving which deleted an existing item.
 */
define('SAVED_DELETED', 3);

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/**
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 * The default group for system CSS files added to the page.
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 */
define('CSS_SYSTEM', -100);

/**
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 * The default group for module CSS files added to the page.
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 */
define('CSS_DEFAULT', 0);

/**
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 * The default group for theme CSS files added to the page.
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 */
define('CSS_THEME', 100);

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/**
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 * The default group for JavaScript libraries, settings or jQuery plugins added
 * to the page.
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 */
define('JS_LIBRARY', -100);

/**
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 * The default group for module JavaScript code added to the page.
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 */
define('JS_DEFAULT', 0);

/**
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 * The default group for theme JavaScript code added to the page.
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 */
define('JS_THEME', 100);

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/**
 * Error code indicating that the request made by drupal_http_request() exceeded
 * the specified timeout.
 */
define('HTTP_REQUEST_TIMEOUT', 1);

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/**
 * Constants defining cache granularity for blocks and renderable arrays.
 *
 * Modules specify the caching patterns for their blocks using binary
 * combinations of these constants in their hook_block_info():
 *   $block[delta]['cache'] = DRUPAL_CACHE_PER_ROLE | DRUPAL_CACHE_PER_PAGE;
 * DRUPAL_CACHE_PER_ROLE is used as a default when no caching pattern is
 * specified. Use DRUPAL_CACHE_CUSTOM to disable standard block cache and
 * implement
 *
 * The block cache is cleared in cache_clear_all(), and uses the same clearing
 * policy than page cache (node, comment, user, taxonomy added or updated...).
 * Blocks requiring more fine-grained clearing might consider disabling the
 * built-in block cache (DRUPAL_NO_CACHE) and roll their own.
 *
 * Note that user 1 is excluded from block caching.
 */

/**
 * The block should not get cached. This setting should be used:
 * - for simple blocks (notably those that do not perform any db query),
 * where querying the db cache would be more expensive than directly generating
 * the content.
 * - for blocks that change too frequently.
 */
define('DRUPAL_NO_CACHE', -1);

/**
 * The block is handling its own caching in its hook_block_view(). From the
 * perspective of the block cache system, this is equivalent to DRUPAL_NO_CACHE.
 * Useful when time based expiration is needed or a site uses a node access
 * which invalidates standard block cache.
 */
define('DRUPAL_CACHE_CUSTOM', -2);

/**
 * The block or element can change depending on the roles the user viewing the
 * page belongs to. This is the default setting for blocks, used when the block
 * does not specify anything.
 */
define('DRUPAL_CACHE_PER_ROLE', 0x0001);

/**
 * The block or element can change depending on the user viewing the page.
 * This setting can be resource-consuming for sites with large number of users,
 * and thus should only be used when DRUPAL_CACHE_PER_ROLE is not sufficient.
 */
define('DRUPAL_CACHE_PER_USER', 0x0002);

/**
 * The block or element can change depending on the page being viewed.
 */
define('DRUPAL_CACHE_PER_PAGE', 0x0004);

/**
 * The block or element is the same for every user on every page where it is visible.
 */
define('DRUPAL_CACHE_GLOBAL', 0x0008);

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/**
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 * Add content to a specified region.
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 *
 * @param $region
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 *   Page region the content is added to.
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 * @param $data
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 *   Content to be added.
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 */
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function drupal_add_region_content($region = NULL, $data = NULL) {
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  static $content = array();

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  if (isset($region) && isset($data)) {
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    $content[$region][] = $data;
  }
  return $content;
}

/**
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 * Get assigned content for a given region.
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 *
 * @param $region
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 *   A specified region to fetch content for. If NULL, all regions will be
 *   returned.
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 * @param $delimiter
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 *   Content to be inserted between imploded array elements.
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 */
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function drupal_get_region_content($region = NULL, $delimiter = ' ') {
  $content = drupal_add_region_content();
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  if (isset($region)) {
    if (isset($content[$region]) && is_array($content[$region])) {
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      return implode($delimiter, $content[$region]);
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    }
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  }
  else {
    foreach (array_keys($content) as $region) {
      if (is_array($content[$region])) {
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        $content[$region] = implode($delimiter, $content[$region]);
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      }
    }
    return $content;
  }
}

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/**
 * Get the name of the currently active install profile.
 *
 * When this function is called during Drupal's initial installation process,
 * the name of the profile that's about to be installed is stored in the global
 * installation state. At all other times, the standard Drupal systems variable
 * table contains the name of the current profile, and we can call variable_get()
 * to determine what one is active.
 *
 * @return $profile
 *   The name of the install profile.
 */
function drupal_get_profile() {
  global $install_state;

  if (isset($install_state['parameters']['profile'])) {
    $profile = $install_state['parameters']['profile'];
  }
  else {
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    $profile = variable_get('install_profile', 'standard');
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  }

  return $profile;
}


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/**
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 * Set the breadcrumb trail for the current page.
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 *
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 * @param $breadcrumb
 *   Array of links, starting with "home" and proceeding up to but not including
 *   the current page.
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 */
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function drupal_set_breadcrumb($breadcrumb = NULL) {
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  $stored_breadcrumb = &drupal_static(__FUNCTION__);
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  if (isset($breadcrumb)) {
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    $stored_breadcrumb = $breadcrumb;
  }
  return $stored_breadcrumb;
}

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/**
 * Get the breadcrumb trail for the current page.
 */
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function drupal_get_breadcrumb() {
  $breadcrumb = drupal_set_breadcrumb();

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  if (!isset($breadcrumb)) {
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    $breadcrumb = menu_get_active_breadcrumb();
  }

  return $breadcrumb;
}

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/**
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 * Returns a string containing RDF namespace declarations for use in XML and
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 * XHTML output.
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 */
function drupal_get_rdf_namespaces() {
  $xml_rdf_namespaces = array();
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  // Serializes the RDF namespaces in XML namespace syntax.
  if (function_exists('rdf_get_namespaces')) {
    foreach (rdf_get_namespaces() as $prefix => $uri) {
      $xml_rdf_namespaces[] = 'xmlns:' . $prefix . '="' . $uri . '"';
    }
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  }
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  return count($xml_rdf_namespaces) ? "\n  " . implode("\n  ", $xml_rdf_namespaces) : '';
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}

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/**
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 * Add output to the head tag of the HTML page.
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 *
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 * This function can be called as long the headers aren't sent. Pass no
 * arguments (or NULL for both) to retrieve the currently stored elements.
 *
 * @param $data
 *   A renderable array. If the '#type' key is not set then 'html_tag' will be
 *   added as the default '#type'.
 * @param $key
 *   A unique string key to allow implementations of hook_html_head_alter() to
 *   identify the element in $data. Required if $data is not NULL.
 *
 * @return
 *   An array of all stored HEAD elements.
 *
 * @see theme_html_tag()
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 */
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function drupal_add_html_head($data = NULL, $key = NULL) {
  $stored_head = &drupal_static(__FUNCTION__);
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  if (!isset($stored_head)) {
    // Make sure the defaults, including Content-Type, come first.
    $stored_head = _drupal_default_html_head();
  }

  if (isset($data) && isset($key)) {
    if (!isset($data['#type'])) {
      $data['#type'] = 'html_tag';
    }
    $stored_head[$key] = $data;
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  }
  return $stored_head;
}

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/**
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 * Returns elements that are always displayed in the HEAD tag of the HTML page.
 */
function _drupal_default_html_head() {
  // Add default elements. Make sure the Content-Type comes first because the
  // IE browser may be vulnerable to XSS via encoding attacks from any content
  // that comes before this META tag, such as a TITLE tag.
  $elements['system_meta_content_type'] = array(
    '#type' => 'html_tag',
    '#tag' => 'meta',
    '#attributes' => array(
      'http-equiv' => 'Content-Type',
      'content' => 'text/html; charset=utf-8',
    ),
    // Security: This always has to be output first.
    '#weight' => -1000,
  );
  // Show Drupal and the major version number in the META GENERATOR tag.
  // Get the major version.
  list($version, ) = explode('.', VERSION);
  $elements['system_meta_generator'] = array(
    '#type' => 'html_tag',
    '#tag' => 'meta',
    '#attributes' => array(
      'name' => 'Generator',
      'content' => 'Drupal ' . $version . ' (http://drupal.org)',
    ),
  );
  // Also send the generator in the HTTP header.
  $elements['system_meta_generator']['#attached']['drupal_add_http_header'][] = array('X-Generator', $elements['system_meta_generator']['#attributes']['content']);
  return $elements;
}

/**
 * Retrieve output to be displayed in the HEAD tag of the HTML page.
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 */
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function drupal_get_html_head() {
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  $elements = drupal_add_html_head();
  drupal_alter('html_head', $elements);
  return drupal_render($elements);
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}

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/**
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 * Add a feed URL for the current page.
 *
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 * This function can be called as long the HTML header hasn't been sent.
 *
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 * @param $url
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 *   An internal system path or a fully qualified external URL of the feed.
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 * @param $title
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 *   The title of the feed.
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 */
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function drupal_add_feed($url = NULL, $title = '') {
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  $stored_feed_links = &drupal_static(__FUNCTION__, array());
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  if (isset($url)) {
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    $stored_feed_links[$url] = theme('feed_icon', array('url' => $url, 'title' => $title));
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    drupal_add_html_head_link(array(
      'rel' => 'alternate',
      'type' => 'application/rss+xml',
      'title' => $title,
      // Force the URL to be absolute, for consistency with other <link> tags
      // output by Drupal.
      'href' => url($url, array('absolute' => TRUE)),
    ));
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  }
  return $stored_feed_links;
}

/**
 * Get the feed URLs for the current page.
 *
 * @param $delimiter
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 *   A delimiter to split feeds by.
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 */
function drupal_get_feeds($delimiter = "\n") {
  $feeds = drupal_add_feed();
  return implode($feeds, $delimiter);
}

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/**
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 * @defgroup http_handling HTTP handling
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 * @{
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 * Functions to properly handle HTTP responses.
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 */

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/**
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 * Process a URL query parameter array to remove unwanted elements.
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 *
 * @param $query
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 *   (optional) An array to be processed. Defaults to $_GET.
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 * @param $exclude
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 *   (optional) A list of $query array keys to remove. Use "parent[child]" to
 *   exclude nested items. Defaults to array('q').
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 * @param $parent
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 *   Internal use only. Used to build the $query array key for nested items.
 *
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 * @return
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 *   An array containing query parameters, which can be used for url().
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 */
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function drupal_get_query_parameters(array $query = NULL, array $exclude = array('q'), $parent = '') {
  // Set defaults, if none given.
  if (!isset($query)) {
    $query = $_GET;
  }
  // If $exclude is empty, there is nothing to filter.
  if (empty($exclude)) {
    return $query;
  }
  elseif (!$parent) {
    $exclude = array_flip($exclude);
  }
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  $params = array();
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  foreach ($query as $key => $value) {
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    $string_key = ($parent ? $parent . '[' . $key . ']' : $key);
    if (isset($exclude[$string_key])) {
      continue;
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    }

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    if (is_array($value)) {
      $params[$key] = drupal_get_query_parameters($value, $exclude, $string_key);
    }
    else {
      $params[$key] = $value;
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    }
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  }

  return $params;
}

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/**
 * Split an URL-encoded query string into an array.
 *
 * @param $query
 *   The query string to split.
 *
 * @return
 *   An array of url decoded couples $param_name => $value.
 */
function drupal_get_query_array($query) {
  $result = array();
  if (!empty($query)) {
    foreach (explode('&', $query) as $param) {
      $param = explode('=', $param);
      $result[$param[0]] = isset($param[1]) ? rawurldecode($param[1]) : '';
    }
  }
  return $result;
}

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/**
 * Parse an array into a valid, rawurlencoded query string.
 *
 * This differs from http_build_query() as we need to rawurlencode() (instead of
 * urlencode()) all query parameters.
 *
 * @param $query
 *   The query parameter array to be processed, e.g. $_GET.
 * @param $parent
 *   Internal use only. Used to build the $query array key for nested items.
 *
 * @return
 *   A rawurlencoded string which can be used as or appended to the URL query
 *   string.
 *
 * @see drupal_get_query_parameters()
 * @ingroup php_wrappers
 */
function drupal_http_build_query(array $query, $parent = '') {
  $params = array();

  foreach ($query as $key => $value) {
    $key = ($parent ? $parent . '[' . rawurlencode($key) . ']' : rawurlencode($key));
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    // Recurse into children.
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    if (is_array($value)) {
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      $params[] = drupal_http_build_query($value, $key);
    }
    // If a query parameter value is NULL, only append its key.
    elseif (!isset($value)) {
      $params[] = $key;
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    }
    else {
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      // For better readability of paths in query strings, we decode slashes.
      $params[] = $key . '=' . str_replace('%2F', '/', rawurlencode($value));
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    }
  }

  return implode('&', $params);
}

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/**
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 * Prepare a 'destination' URL query parameter for use in combination with drupal_goto().
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 *
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 * Used to direct the user back to the referring page after completing a form.
 * By default the current URL is returned. If a destination exists in the
 * previous request, that destination is returned. As such, a destination can
 * persist across multiple pages.
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 *
 * @see drupal_goto()
 */
function drupal_get_destination() {
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  $destination = &drupal_static(__FUNCTION__);

  if (isset($destination)) {
    return $destination;
  }

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  if (isset($_GET['destination'])) {
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    $destination = array('destination' => $_GET['destination']);
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  }
  else {
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    $path = $_GET['q'];
    $query = drupal_http_build_query(drupal_get_query_parameters());
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    if ($query != '') {
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      $path .= '?' . $query;
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    }
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    $destination = array('destination' => $path);
  }
  return $destination;
}

/**
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 * Wrapper around parse_url() to parse a system URL string into an associative array, suitable for url().
 *
 * This function should only be used for URLs that have been generated by the
 * system, resp. url(). It should not be used for URLs that come from external
 * sources, or URLs that link to external resources.
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 *
 * The returned array contains a 'path' that may be passed separately to url().
 * For example:
 * @code
 *   $options = drupal_parse_url($_GET['destination']);
 *   $my_url = url($options['path'], $options);
 *   $my_link = l('Example link', $options['path'], $options);
 * @endcode
 *
 * This is required, because url() does not support relative URLs containing a
 * query string or fragment in its $path argument. Instead, any query string
 * needs to be parsed into an associative query parameter array in
 * $options['query'] and the fragment into $options['fragment'].
 *
 * @param $url
 *   The URL string to parse, f.e. $_GET['destination'].
 *
 * @return
 *   An associative array containing the keys:
 *   - 'path': The path of the URL. If the given $url is external, this includes
 *     the scheme and host.
 *   - 'query': An array of query parameters of $url, if existent.
 *   - 'fragment': The fragment of $url, if existent.
 *
 * @see url()
 * @see drupal_goto()
 * @ingroup php_wrappers
 */
function drupal_parse_url($url) {
  $options = array(
    'path' => NULL,
    'query' => array(),
    'fragment' => '',
  );

  // External URLs: not using parse_url() here, so we do not have to rebuild
  // the scheme, host, and path without having any use for it.
  if (strpos($url, '://') !== FALSE) {
    // Split off everything before the query string into 'path'.
    $parts = explode('?', $url);
    $options['path'] = $parts[0];
    // If there is a query string, transform it into keyed query parameters.
    if (isset($parts[1])) {
      $query_parts = explode('#', $parts[1]);
      parse_str($query_parts[0], $options['query']);
      // Take over the fragment, if there is any.
      if (isset($query_parts[1])) {
        $options['fragment'] = $query_parts[1];
      }
    }
  }
  // Internal URLs.
  else {
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    // parse_url() does not support relative URLs, so make it absolute. E.g. the
    // relative URL "foo/bar:1" isn't properly parsed.
    $parts = parse_url('http://example.com/' . $url);
    // Strip the leading slash that was just added.
    $options['path'] = substr($parts['path'], 1);
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    if (isset($parts['query'])) {
      parse_str($parts['query'], $options['query']);
    }
    if (isset($parts['fragment'])) {
      $options['fragment'] = $parts['fragment'];
    }
  }
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  // The 'q' parameter contains the path of the current page if clean URLs are
  // disabled. It overrides the 'path' of the URL when present, even if clean
  // URLs are enabled, due to how Apache rewriting rules work.
  if (isset($options['query']['q'])) {
    $options['path'] = $options['query']['q'];
    unset($options['query']['q']);
  }
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  return $options;
}

/**
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 * Encodes a Drupal path for use in a URL.
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 *
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 * For aesthetic reasons slashes are not escaped.
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 *
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 * Note that url() takes care of calling this function, so a path passed to that
 * function should not be encoded in advance.
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 *
 * @param $path
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 *   The Drupal path to encode.
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 */
function drupal_encode_path($path) {
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  return str_replace('%2F', '/', rawurlencode($path));
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}

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/**
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 * Send the user to a different Drupal page.
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 *
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 * This issues an on-site HTTP redirect. The function makes sure the redirected
 * URL is formatted correctly.
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 *
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 * Usually the redirected URL is constructed from this function's input
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 * parameters. However you may override that behavior by setting a
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 * destination in either the $_REQUEST-array (i.e. by using
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 * the query string of an URI) This is used to direct the user back to
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 * the proper page after completing a form. For example, after editing
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 * a post on the 'admin/content'-page or after having logged on using the
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 * 'user login'-block in a sidebar. The function drupal_get_destination()
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 * can be used to help set the destination URL.
 *
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 * Drupal will ensure that messages set by drupal_set_message() and other
 * session data are written to the database before the user is redirected.
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 *
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 * This function ends the request; use it instead of a return in your menu
 * callback.
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 *
 * @param $path
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 *   A Drupal path or a full URL.
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 * @param $options
 *   An associative array of additional URL options to pass to url().
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 * @param $http_response_code
 *   Valid values for an actual "goto" as per RFC 2616 section 10.3 are:
 *   - 301 Moved Permanently (the recommended value for most redirects)
 *   - 302 Found (default in Drupal and PHP, sometimes used for spamming search
 *         engines)
 *   - 303 See Other
 *   - 304 Not Modified
 *   - 305 Use Proxy
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 *   - 307 Temporary Redirect (alternative to "503 Site Down for Maintenance")
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 *   Note: Other values are defined by RFC 2616, but are rarely used and poorly
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 *   supported.
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 *
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 * @see drupal_get_destination()
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 * @see url()
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 */
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function drupal_goto($path = '', array $options = array(), $http_response_code = 302) {
  // A destination in $_GET always overrides the function arguments.
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  // We do not allow absolute URLs to be passed via $_GET, as this can be an attack vector.
  if (isset($_GET['destination']) && !url_is_external($_GET['destination'])) {
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    $destination = drupal_parse_url($_GET['destination']);
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    $path = $destination['path'];
    $options['query'] = $destination['query'];
    $options['fragment'] = $destination['fragment'];
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  }

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  drupal_alter('drupal_goto', $path, $options, $http_response_code);

  // The 'Location' HTTP header must be absolute.
  $options['absolute'] = TRUE;
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  $url = url($path, $options);
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  header('Location: ' . $url, TRUE, $http_response_code);
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  // The "Location" header sends a redirect status code to the HTTP daemon. In
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  // some cases this can be wrong, so we make sure none of the code below the
  // drupal_goto() call gets executed upon redirection.
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  drupal_exit($url);
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}

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/**
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 * Deliver a "site is under maintenance" message to the browser.
 *
 * Page callback functions wanting to report a "site offline" message should
 * return MENU_SITE_OFFLINE instead of calling drupal_site_offline(). However,
 * functions that are invoked in contexts where that return value might not
 * bubble up to menu_execute_active_handler() should call drupal_site_offline().
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 */
function drupal_site_offline() {
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  drupal_deliver_page(MENU_SITE_OFFLINE);
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}

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/**
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 * Deliver a "page not found" error to the browser.
 *
 * Page callback functions wanting to report a "page not found" message should
 * return MENU_NOT_FOUND instead of calling drupal_not_found(). However,
 * functions that are invoked in contexts where that return value might not
 * bubble up to menu_execute_active_handler() should call drupal_not_found().
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 */
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function drupal_not_found() {
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  drupal_deliver_page(MENU_NOT_FOUND);
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}
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/**
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 * Deliver a "access denied" error to the browser.
 *
 * Page callback functions wanting to report an "access denied" message should
 * return MENU_ACCESS_DENIED instead of calling drupal_access_denied(). However,
 * functions that are invoked in contexts where that return value might not
 * bubble up to menu_execute_active_handler() should call drupal_access_denied().
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 */
function drupal_access_denied() {
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  drupal_deliver_page(MENU_ACCESS_DENIED);
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}

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/**
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 * Perform an HTTP request.
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 *
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 * This is a flexible and powerful HTTP client implementation. Correctly
 * handles GET, POST, PUT or any other HTTP requests. Handles redirects.
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 *
 * @param $url
 *   A string containing a fully qualified URI.
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 * @param array $options
 *   (optional) An array that can have one or more of the following elements:
 *   - headers: An array containing request headers to send as name/value pairs.
 *   - method: A string containing the request method. Defaults to 'GET'.
 *   - data: A string containing the request body, formatted as
 *     'param=value&param=value&...'. Defaults to NULL.
 *   - max_redirects: An integer representing how many times a redirect
 *     may be followed. Defaults to 3.
 *   - timeout: A float representing the maximum number of seconds the function
 *     call may take. The default is 30 seconds. If a timeout occurs, the error
 *     code is set to the HTTP_REQUEST_TIMEOUT constant.
 *   - context: A context resource created with stream_context_create().
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 *
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 * @return object
 *   An object that can have one or more of the following components:
 *   - request: A string containing the request body that was sent.
 *   - code: An integer containing the response status code, or the error code
 *     if an error occurred.
 *   - protocol: The response protocol (e.g. HTTP/1.1 or HTTP/1.0).
 *   - status_message: The status message from the response, if a response was
 *     received.
 *   - redirect_code: If redirected, an integer containing the initial response
 *     status code.
 *   - redirect_url: If redirected, a string containing the redirection location.
 *   - error: If an error occurred, the error message. Otherwise not set.
 *   - headers: An array containing the response headers as name/value pairs.
 *     HTTP header names are case-insensitive (RFC 2616, section 4.2), so for
 *     easy access the array keys are returned in lower case.
 *   - data: A string containing the response body that was received.
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 */
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function drupal_http_request($url, array $options = array()) {
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  $result = new stdClass();
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  // Parse the URL and make sure we can handle the schema.
  $uri = @parse_url($url);

  if ($uri == FALSE) {
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    $result->error = 'unable to parse URL';
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    $result->code = -1001;
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    return $result;
  }

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  if (!isset($uri['scheme'])) {
    $result->error = 'missing schema';
    $result->code = -1002;
    return $result;
  }
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  timer_start(__FUNCTION__);

  // Merge the default options.
  $options += array(
    'headers' => array(),
    'method' => 'GET',
    'data' => NULL,
    'max_redirects' => 3,
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    'timeout' => 30.0,
    'context' => NULL,
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  );
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  // stream_socket_client() requires timeout to be a float.
  $options['timeout'] = (float) $options['timeout'];
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  switch ($uri['scheme']) {
    case 'http':
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    case 'feed':
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      $port = isset($uri['port']) ? $uri['port'] : 80;
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      $socket = 'tcp://' . $uri['host'] . ':' . $port;
      // RFC 2616: "non-standard ports MUST, default ports MAY be included".
      // We don't add the standard port to prevent from breaking rewrite rules
      // checking the host that do not take into account the port number.
      $options['headers']['Host'] = $uri['host'] . ($port != 80 ? ':' . $port : '');
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      break;
    case 'https':
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      // Note: Only works when PHP is compiled with OpenSSL support.
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      $port = isset($uri['port']) ? $uri['port'] : 443;
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      $socket = 'ssl://' . $uri['host'] . ':' . $port;
      $options['headers']['Host'] = $uri['host'] . ($port != 443 ? ':' . $port : '');
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      break;
    default:
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      $result->error = 'invalid schema ' . $uri['scheme'];
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      $result->code = -1003;
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      return $result;
  }

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  if (empty($options['context'])) {
    $fp = @stream_socket_client($socket, $errno, $errstr, $options['timeout']);
  }
  else {
    // Create a stream with context. Allows verification of a SSL certificate.
    $fp = @stream_socket_client($socket, $errno, $errstr, $options['timeout'], STREAM_CLIENT_CONNECT, $options['context']);
  }

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  // Make sure the socket opened properly.
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  if (!$fp) {
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    // When a network error occurs, we use a negative number so it does not
    // clash with the HTTP status codes.
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    $result->code = -$errno;
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    $result->error = trim($errstr) ? trim($errstr) : t('Error opening socket @socket', array('@socket' => $socket));
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    // Mark that this request failed. This will trigger a check of the web
    // server's ability to make outgoing HTTP requests the next time that
    // requirements checking is performed.
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    // See system_requirements()
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    variable_set('drupal_http_request_fails', TRUE);

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    return $result;
  }

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  // Construct the path to act on.
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  $path = isset($uri['path']) ? $uri['path'] : '/';
  if (isset($uri['query'])) {
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    $path .= '?' . $uri['query'];
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  }

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  // Merge the default headers.
  $options['headers'] += array(
    'User-Agent' => 'Drupal (+http://drupal.org/)',
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  );

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  // Only add Content-Length if we actually have any content or if it is a POST
  // or PUT request. Some non-standard servers get confused by Content-Length in
  // at least HEAD/GET requests, and Squid always requires Content-Length in
  // POST/PUT requests.
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  $content_length = strlen($options['data']);
  if ($content_length > 0 || $options['method'] == 'POST' || $options['method'] == 'PUT') {
    $options['headers']['Content-Length'] = $content_length;
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  }

  // If the server URL has a user then attempt to use basic authentication.
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  if (isset($uri['user'])) {
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    $options['headers']['Authorization'] = 'Basic ' . base64_encode($uri['user'] . (!empty($uri['pass']) ? ":" . $uri['pass'] : ''));
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  }

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  // If the database prefix is being used by SimpleTest to run the tests in a copied
  // database then set the user-agent header to the database prefix so that any
  // calls to other Drupal pages will run the SimpleTest prefixed database. The
  // user-agent is used to ensure that multiple testing sessions running at the
  // same time won't interfere with each other as they would if the database
  // prefix were stored statically in a file or database variable.
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  $test_info = &$GLOBALS['drupal_test_info'];
  if (!empty($test_info['test_run_id'])) {
    $options['headers']['User-Agent'] = drupal_generate_test_ua($test_info['test_run_id']);
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  }

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  $request = $options['method'] . ' ' . $path . " HTTP/1.0\r\n";
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  foreach ($options['headers'] as $name => $value) {
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    $request .= $name . ': ' . trim($value) . "\r\n";
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  }
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  $request .= "\r\n" . $options['data'];
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  $result->request = $request;
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  // Calculate how much time is left of the original timeout value.
  $timeout = $options['timeout'] - timer_read(__FUNCTION__) / 1000;
  if ($timeout > 0) {
    stream_set_timeout($fp, floor($timeout), floor(1000000 * fmod($timeout, 1)));
    fwrite($fp, $request);
  }
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  // Fetch response. Due to PHP bugs like http://bugs.php.net/bug.php?id=43782
  // and http://bugs.php.net/bug.php?id=46049 we can't rely on feof(), but
  // instead must invoke stream_get_meta_data() each iteration.
  $info = stream_get_meta_data($fp);
  $alive = !$info['eof'] && !$info['timed_out'];
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  $response = '';
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  while ($alive) {
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    // Calculate how much time is left of the original timeout value.
    $timeout = $options['timeout'] - timer_read(__FUNCTION__) / 1000;
    if ($timeout <= 0) {
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      $info['timed_out'] = TRUE;
      break;
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    }
    stream_set_timeout($fp, floor($timeout), floor(1000000 * fmod($timeout, 1)));
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    $chunk = fread($fp, 1024);
    $response .= $chunk;
    $info = stream_get_meta_data($fp);
    $alive = !$info['eof'] && !$info['timed_out'] && $chunk;
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  }
  fclose($fp);

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  if ($info['timed_out']) {
    $result->code = HTTP_REQUEST_TIMEOUT;
    $result->error = 'request timed out';
    return $result;
  }
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  // Parse response headers from the response body.
  list($response, $result->data) = explode("\r\n\r\n", $response, 2);
  $response = preg_split("/\r\n|\n|\r/", $response);
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  // Parse the response status line.
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  list($protocol, $code, $status_message) = explode(' ', trim(array_shift($response)), 3);
  $result->protocol = $protocol;
  $result->status_message = $status_message;

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  $result->headers = array();

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  // Parse the response headers.
  while ($line = trim(array_shift($response))) {
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    list($name, $value) = explode(':', $line, 2);
    $name = strtolower($name);
    if (isset($result->headers[$name]) && $name == 'set-cookie') {
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      // RFC 2109: the Set-Cookie response header comprises the token Set-
      // Cookie:, followed by a comma-separated list of one or more cookies.
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      $result->headers[$name] .= ',' . trim($value);
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    }
    else {
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      $result->headers[$name] = trim($value);
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    }
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  }

  $responses = array(
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    100 => 'Continue',
    101 => 'Switching Protocols',
    200 => 'OK',
    201 => 'Created',
    202 => 'Accepted',
    203 => 'Non-Authoritative Information',
    204 => 'No Content',
    205 => 'Reset Content',
    206 => 'Partial Content',
    300 => 'Multiple Choices',
    301 => 'Moved Permanently',
    302 => 'Found',
    303 => 'See Other',
    304 => 'Not Modified',
    305 => 'Use Proxy',
    307 => 'Temporary Redirect',
    400 => 'Bad Request',
    401 => 'Unauthorized',
    402 => 'Payment Required',
    403 => 'Forbidden',
    404 => 'Not Found',
    405 => 'Method Not Allowed',
    406 => 'Not Acceptable',
    407 => 'Proxy Authentication Required',
    408 => 'Request Time-out',
    409 => 'Conflict',
    410 => 'Gone',
    411 => 'Length Required',
    412 => 'Precondition Failed',
    413 => 'Request Entity Too Large',
    414 => 'Request-URI Too Large',
    415 => 'Unsupported Media Type',
    416 => 'Requested range not satisfiable',
    417 => 'Expectation Failed',
    500 => 'Internal Server Error',
    501 => 'Not Implemented',
    502 => 'Bad Gateway',
    503 => 'Service Unavailable',
    504 => 'Gateway Time-out',
    505 => 'HTTP Version not supported',
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  );
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  // RFC 2616 states that all unknown HTTP codes must be treated the same as the
  // base code in their class.
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  if (!isset($responses[$code])) {
    $code = floor($code / 100) * 100;
  }
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  $result->code = $code;
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  switch ($code) {
    case 200: // OK
    case 304: // Not modified
      break;
    case 301: // Moved permanently
    case 302: // Moved temporarily
    case 307: // Moved temporarily
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      $location = $result->headers['location'];
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      $options['timeout'] -= timer_read(__FUNCTION__) / 1000;
      if ($options['timeout'] <= 0) {
        $result->code = HTTP_REQUEST_TIMEOUT;
        $result->error = 'request timed out';
      }
      elseif ($options['max_redirects']) {
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        // Redirect to the new location.
        $options['max_redirects']--;
        $result = drupal_http_request($location, $options);
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        $result->redirect_code = $code;
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      }
      $result->redirect_url = $location;
      break;
    default:
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      $result->error = $status_message;
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  }

  return $result;
}
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/**
 * @} End of "HTTP handling".
 */
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function _fix_gpc_magic(&$item) {
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  if (is_array($item)) {
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    array_walk($item, '_fix_gpc_magic');
  }
  else {
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    $item = stripslashes($item);
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  }
}

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/**
 * Helper function to strip slashes from $_FILES skipping over the tmp_name keys
 * since PHP generates single backslashes for file paths on Windows systems.
 *
 * tmp_name does not have backslashes added see
 * http://php.net/manual/en/features.file-upload.php#42280
 */
function _fix_gpc_magic_files(&$item, $key) {
  if ($key != 'tmp_name') {
    if (is_array($item)) {
      array_walk($item, '_fix_gpc_magic_files');
    }
    else {
      $item = stripslashes($item);
    }
  }
}

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/**
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 * Fix double-escaping problems caused by "magic quotes" in some PHP installations.
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 */
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function fix_gpc_magic() {
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  $fixed = &drupal_static(__FUNCTION__, FALSE);
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  if (!$fixed && ini_get('magic_quotes_gpc')) {
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    array_walk($_GET, '_fix_gpc_magic');
    array_walk($_POST, '_fix_gpc_magic');
    array_walk($_COOKIE, '_fix_gpc_magic');
    array_walk($_REQUEST, '_fix_gpc_magic');
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    array_walk($_FILES, '_fix_gpc_magic_files');
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    $fixed = TRUE;
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  }
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}

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/**
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 * @defgroup validation Input validation
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 * @{
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 * Functions to validate user input.
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 */

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/**
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 * Verify the syntax of the given e-mail address.
 *
 * Empty e-mail addresses are allowed. See RFC 2822 for details.
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 *
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 * @param $mail
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 *   A string containing an e-mail address.
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 * @return
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 *   TRUE if the address is in a valid format.
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 */
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function valid_email_address($mail) {
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  return (bool)filter_var($mail, FILTER_VALIDATE_EMAIL);
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}

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/**
 * Verify the syntax of the given URL.
 *
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 * This function should only be used on actual URLs. It should not be used for
 * Drupal menu paths, which can contain arbitrary characters.
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 * Valid values per RFC 3986.
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 * @param $url
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 *   The URL to verify.
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 * @param $absolute
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 *   Whether the URL is absolute (beginning with a scheme such as "http:").
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 * @return
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 *   TRUE if the URL is in a valid format.
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 */
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function valid_url($url, $absolute = FALSE) {
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  if ($absolute) {
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    return (bool)preg_match("
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      /^                                                      # Start at the beginning of the text
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      (?:ftp|https?|feed):\/\/                                # Look for ftp, http, https or feed schemes
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      (?:                                                     # Userinfo (optional) which is typically
        (?:(?:[\w\.\-\+!$&'\(\)*\+,;=]|%[0-9a-f]{2})+:)*      # a username or a username and password
        (?:[\w\.\-\+%!$&'\(\)*\+,;=]|%[0-9a-f]{2})+@          # combination
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      )?
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      (?:
        (?:[a-z0-9\-\.]|%[0-9a-f]{2})+                        # A domain name or a IPv4 address
        |(?:\[(?:[0-9a-f]{0,4}:)*(?:[0-9a-f]{0,4})\])         # or a well formed IPv6 address
      )
      (?::[0-9]+)?                                            # Server port number (optional)
      (?:[\/|\?]
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        (?:[\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2})   # The path and query (optional)
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      *)?
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    $/xi", $url);
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  }
  else {
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    return (bool)preg_match("/^(?:[\w#!:\.\?\+=&@$'~*,;\/\(\)\[\]\-]|%[0-9a-f]{2})+$/i", $url);
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  }
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}

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/**
 * @} End of "defgroup validation".
 */

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/**
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 * Register an event for the current visitor to the flood control mechanism.
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 *
 * @param $name
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 *   The name of an event.
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 * @param $window
 *   Optional number of seconds before this event expires. Defaults to 3600 (1
 *   hour). Typically uses the same value as the flood_is_allowed() $window
 *   parameter. Expired events are purged on cron run to prevent the flood table
 *   from growing indefinitely.
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 * @param $identifier
 *   Optional identifier (defaults to the current user's IP address).
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 */
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function flood_register_event($name, $window = 3600, $identifier = NULL) {
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  if (!isset($identifier)) {
    $identifier = ip_address();
  }
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  db_insert('flood')
    ->fields(array(
      'event' => $name,
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      'identifier' => $identifier,
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      'timestamp' => REQUEST_TIME,
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      'expiration' => REQUEST_TIME + $window,
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    ))
    ->execute();
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}

/**
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 * Make the flood control mechanism forget about an event for the current visitor.
 *
 * @param $name
 *   The name of an event.
 * @param $identifier
 *   Optional identifier (defaults to the current user's IP address).
 */
function flood_clear_event($name, $identifier = NULL) {
  if (!isset($identifier)) {
    $identifier = ip_address();
  }
  db_delete('flood')
    ->condition('event', $name)
    ->condition('identifier', $identifier)
    ->execute();
}

/**
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 * Checks whether user is allowed to proceed with the specified event.
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 *
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 * Events can have thresholds saying that each user can only do that event
 * a certain number of times in a time window. This function verifies that the
 * current user has not exceeded this threshold.
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 *
 * @param $name
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 *   The unique name of the event.
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 * @param $threshold
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 *   The maximum number of times each user can do this event per time window.
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 * @param $window
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 *   Number of seconds in the time window for this event (default is 3600
 *   seconds, or 1 hour).