aggregator.module

<?php
// $Id$

/**
 * @file
 * Used to aggregate syndicated content (RSS, RDF, and Atom).
 */

/**
 * Implementation of hook_help().
 */
function aggregator_help($path, $arg) {
  switch ($path) {
    case 'admin/help#aggregator':
      $output = '<p>' . t('The aggregator is a powerful on-site syndicator and news reader that gathers fresh content from RSS-, RDF-, and Atom-based feeds made available across the web. Thousands of sites (particularly news sites and blogs) publish their latest headlines and posts in feeds, using a number of standardized XML-based formats. Formats supported by the aggregator include <a href="@rss">RSS</a>, <a href="@rdf">RDF</a>, and <a href="@atom">Atom</a>.', array('@rss' => 'http://cyber.law.harvard.edu/rss/', '@rdf' => 'http://www.w3.org/RDF/', '@atom' => 'http://www.atomenabled.org')) . '</p>';
      $output .= '<p>' . t('Feeds contain feed items, or individual posts published by the site providing the feed. Feeds may be grouped in categories, generally by topic. Users view feed items in the <a href="@aggregator">main aggregator display</a> or by <a href="@aggregator-sources">their source</a>. Administrators can <a href="@feededit">add, edit and delete feeds</a> and choose how often to check each feed for newly updated items. The most recent items in either a feed or category can be displayed as a block through the <a href="@admin-block">blocks administration page</a>. A <a href="@aggregator-opml">machine-readable OPML file</a> of all feeds is available. A correctly configured <a href="@cron">cron maintenance task</a> is required to update feeds automatically.', array('@aggregator' => url('aggregator'), '@aggregator-sources' => url('aggregator/sources'), '@feededit' => url('admin/content/aggregator'), '@admin-block' => url('admin/build/block'), '@aggregator-opml' => url('aggregator/opml'), '@cron' => url('admin/reports/status'))) . '</p>';
      $output .= '<p>' . t('For more information, see the online handbook entry for <a href="@aggregator">Aggregator module</a>.', array('@aggregator' => 'http://drupal.org/handbook/modules/aggregator/')) . '</p>';
      return $output;
    case 'admin/content/aggregator':
      $output = '<p>' . t('Thousands of sites (particularly news sites and blogs) publish their latest headlines and posts in feeds, using a number of standardized XML-based formats. Formats supported by the aggregator include <a href="@rss">RSS</a>, <a href="@rdf">RDF</a>, and <a href="@atom">Atom</a>.', array('@rss' => 'http://cyber.law.harvard.edu/rss/', '@rdf' => 'http://www.w3.org/RDF/', '@atom' => 'http://www.atomenabled.org')) . '</p>';
      $output .= '<p>' . t('Current feeds are listed below, and <a href="@addfeed">new feeds may be added</a>. For each feed or feed category, the <em>latest items</em> block may be enabled at the <a href="@block">blocks administration page</a>.', array('@addfeed' => url('admin/content/aggregator/add/feed'), '@block' => url('admin/build/block'))) . '</p>';
      return $output;
    case 'admin/content/aggregator/add/feed':
      return '<p>' . t('Add a feed in RSS, RDF or Atom format. A feed may only have one entry.') . '</p>';
    case 'admin/content/aggregator/add/category':
      return '<p>' . t('Categories allow feed items from different feeds to be grouped together. For example, several sport-related feeds may belong to a category named <em>Sports</em>. Feed items may be grouped automatically (by selecting a category when creating or editing a feed) or manually (via the <em>Categorize</em> page available from feed item listings). Each category provides its own feed page and block.') . '</p>';
    case 'admin/content/aggregator/add/opml':
      return '<p>' . t('<acronym title="Outline Processor Markup Language">OPML</acronym> is an XML format used to exchange multiple feeds between aggregators. A single OPML document may contain a collection of many feeds. Drupal can parse such a file and import all feeds at once, saving you the effort of adding them manually. You may either upload a local file from your computer or enter a URL where Drupal can download it.') . '</p>';
  }
}

/**
 * Implementation of hook_theme().
 */
function aggregator_theme() {
  return array(
    'aggregator_wrapper' => array(
      'arguments' => array('content' => NULL),
      'file' => 'aggregator.pages.inc',
      'template' => 'aggregator-wrapper',
    ),
    'aggregator_categorize_items' => array(
      'arguments' => array('form' => NULL),
      'file' => 'aggregator.pages.inc',
    ),
    'aggregator_feed_source' => array(
      'arguments' => array('feed' => NULL),
      'file' => 'aggregator.pages.inc',
      'template' => 'aggregator-feed-source',
    ),
    'aggregator_block_item' => array(
      'arguments' => array('item' => NULL, 'feed' => 0),
    ),
    'aggregator_summary_items' => array(
      'arguments' => array('summary_items' => NULL, 'source' => NULL),
      'file' => 'aggregator.pages.inc',
      'template' => 'aggregator-summary-items',
    ),
    'aggregator_summary_item' => array(
      'arguments' => array('item' => NULL),
      'file' => 'aggregator.pages.inc',
      'template' => 'aggregator-summary-item',
    ),
    'aggregator_item' => array(
      'arguments' => array('item' => NULL),
      'file' => 'aggregator.pages.inc',
      'template' => 'aggregator-item',
    ),
    'aggregator_page_opml' => array(
      'arguments' => array('feeds' => NULL),
      'file' => 'aggregator.pages.inc',
    ),
    'aggregator_page_rss' => array(
      'arguments' => array('feeds' => NULL, 'category' => NULL),
      'file' => 'aggregator.pages.inc',
    ),
  );
}

/**
 * Implementation of hook_menu().
 */
function aggregator_menu() {
  $items['admin/content/aggregator'] = array(
    'title' => 'Feed aggregator',
    'description' => "Configure which content your site aggregates from other sites, how often it polls them, and how they're categorized.",
    'page callback' => 'aggregator_admin_overview',
    'access arguments' => array('administer news feeds'),
  );
  $items['admin/content/aggregator/add/feed'] = array(
    'title' => 'Add feed',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_feed'),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/content/aggregator',
  );
  $items['admin/content/aggregator/add/category'] = array(
    'title' => 'Add category',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_category'),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/content/aggregator',
  );
  $items['admin/content/aggregator/add/opml'] = array(
    'title' => 'Import OPML',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_opml'),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
    'parent' => 'admin/content/aggregator',
  );
  $items['admin/content/aggregator/remove/%aggregator_feed'] = array(
    'title' => 'Remove items',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_admin_remove_feed', 4),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/content/aggregator/update/%aggregator_feed'] = array(
    'title' => 'Update items',
    'page callback' => 'aggregator_admin_refresh_feed',
    'page arguments' => array(4),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/content/aggregator/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/content/aggregator/settings'] = array(
    'title' => 'Settings',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_admin_settings'),
    'type' => MENU_LOCAL_TASK,
    'weight' => 10,
    'access arguments' => array('administer news feeds'),
  );
  $items['aggregator'] = array(
    'title' => 'Feed aggregator',
    'page callback' => 'aggregator_page_last',
    'access arguments' => array('access news feeds'),
    'weight' => 5,
  );
  $items['aggregator/sources'] = array(
    'title' => 'Sources',
    'page callback' => 'aggregator_page_sources',
    'access arguments' => array('access news feeds'),
  );
  $items['aggregator/categories'] = array(
    'title' => 'Categories',
    'page callback' => 'aggregator_page_categories',
    'access callback' => '_aggregator_has_categories',
  );
  $items['aggregator/rss'] = array(
    'title' => 'RSS feed',
    'page callback' => 'aggregator_page_rss',
    'access arguments' => array('access news feeds'),
    'type' => MENU_CALLBACK,
  );
  $items['aggregator/opml'] = array(
    'title' => 'OPML feed',
    'page callback' => 'aggregator_page_opml',
    'access arguments' => array('access news feeds'),
    'type' => MENU_CALLBACK,
  );
  $items['aggregator/categories/%aggregator_category'] = array(
    'title callback' => '_aggregator_category_title',
    'title arguments' => array(2),
    'page callback' => 'aggregator_page_category',
    'page arguments' => array(2),
    'access callback' => 'user_access',
    'access arguments' => array('access news feeds'),
  );
  $items['aggregator/categories/%aggregator_category/view'] = array(
    'title' => 'View',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['aggregator/categories/%aggregator_category/categorize'] = array(
    'title' => 'Categorize',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_page_category', 2),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
  );
  $items['aggregator/categories/%aggregator_category/configure'] = array(
    'title' => 'Configure',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_category', 2),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
    'weight' => 1,
  );
  $items['aggregator/sources/%aggregator_feed'] = array(
    'page callback' => 'aggregator_page_source',
    'page arguments' => array(2),
    'access arguments' => array('access news feeds'),
    'type' => MENU_CALLBACK,
  );
  $items['aggregator/sources/%aggregator_feed/view'] = array(
    'title' => 'View',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['aggregator/sources/%aggregator_feed/categorize'] = array(
    'title' => 'Categorize',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_page_source', 2),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
  );
  $items['aggregator/sources/%aggregator_feed/configure'] = array(
    'title' => 'Configure',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_feed', 2),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_LOCAL_TASK,
    'weight' => 1,
  );
  $items['admin/content/aggregator/edit/feed/%aggregator_feed'] = array(
    'title' => 'Edit feed',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_feed', 5),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_CALLBACK,
  );
  $items['admin/content/aggregator/edit/category/%aggregator_category'] = array(
    'title' => 'Edit category',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('aggregator_form_category', 5),
    'access arguments' => array('administer news feeds'),
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Menu callback.
 *
 * @return
 *   An aggregator category title.
 */
function _aggregator_category_title($category) {
  return $category['title'];
}

/**
 * Implementation of hook_init().
 */
function aggregator_init() {
  drupal_add_css(drupal_get_path('module', 'aggregator') . '/aggregator.css');
}

/**
 * Find out whether there are any aggregator categories.
 *
 * @return
 *   TRUE if there is at least one category and the user has access to them, FALSE otherwise.
 */
function _aggregator_has_categories() {
  return user_access('access news feeds') && db_query('SELECT COUNT(*) FROM {aggregator_category}')->fetchField();
}

/**
 * Implementation of hook_perm().
 */
function aggregator_perm() {
  return array(
    'administer news feeds' => array(
      'title' => t('Administer news feeds'),
      'description' => t('Add, edit or delete news feeds that are aggregated to your site.'),
    ),
    'access news feeds' => array(
      'title' => t('Access news feeds'),
      'description' => t('View aggregated news feed items.'),
    ),
  );
}

/**
 * Implementation of hook_cron().
 *
 * Checks news feeds for updates once their refresh interval has elapsed.
 */
function aggregator_cron() {
  $result = db_query('SELECT * FROM {aggregator_feed} WHERE checked + refresh < :time', array(':time' => REQUEST_TIME));
  foreach ($result as $feed) {
    aggregator_refresh((array)$feed);
  }
}

/**
 * Implementation of hook_block().
 *
 * Generates blocks for the latest news items in each category and feed.
 */
function aggregator_block($op = 'list', $delta = '', $edit = array()) {
  if (user_access('access news feeds')) {
    if ($op == 'list') {
      $result = db_query('SELECT cid, title FROM {aggregator_category} ORDER BY title');
      foreach ($result as $category) {
        $block['category-' . $category->cid]['info'] = t('!title category latest items', array('!title' => $category->title));
      }
      $result = db_query('SELECT fid, title FROM {aggregator_feed} WHERE block <> 0 ORDER BY fid');
      foreach ($result as $feed) {
        $block['feed-' . $feed->fid]['info'] = t('!title feed latest items', array('!title' => $feed->title));
      }
    }
    elseif ($op == 'configure') {
      list($type, $id) = explode('-', $delta);
      if ($type == 'category') {
        $value = db_query('SELECT block FROM {aggregator_category} WHERE cid = :cid', array(':cid' => $id))->fetchField();
        $form['block'] = array(
          '#type' => 'select',
          '#title' => t('Number of news items in block'),
          '#default_value' => $value,
          '#options' => drupal_map_assoc(array(2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20))
        );
        return $form;
      }
    }
    elseif ($op == 'save') {
      list($type, $id) = explode('-', $delta);
      if ($type == 'category') {
        db_merge('aggregator_category')
          ->key(array('cid' => $id))
          ->fields(array('block' => $edit['block']))
          ->execute();
      }
    }
    elseif ($op == 'view') {
      list($type, $id) = explode('-', $delta);
      switch ($type) {
        case 'feed':
          if ($feed = db_query('SELECT fid, title, block FROM {aggregator_feed} WHERE block <> 0 AND fid = :fid', array(':fid' => $id))->fetchObject()) {
            $block['subject'] = check_plain($feed->title);
            $result = db_query_range("SELECT * FROM {aggregator_item} WHERE fid = :fid ORDER BY timestamp DESC, iid DESC", array(':fid' => $id), 0, $feed->block);
            $read_more = theme('more_link', url('aggregator/sources/' . $feed->fid), t("View this feed's recent news."));
          }
          break;

        case 'category':
          if ($category = db_query('SELECT cid, title, block FROM {aggregator_category} WHERE cid = :cid', array(':cid' => $id))->fetchObject()) {
            $block['subject'] = check_plain($category->title);
            $result = db_query_range('SELECT i.* FROM {aggregator_category_item} ci LEFT JOIN {aggregator_item} i ON ci.iid = i.iid WHERE ci.cid = :cid ORDER BY i.timestamp DESC, i.iid DESC', array(':cid' => $category->cid), 0, $category->block);
            $read_more = theme('more_link', url('aggregator/categories/' . $category->cid), t("View this category's recent news."));
          }
          break;
      }
      $items = array();
      foreach ($result as $item) {
        $items[] = theme('aggregator_block_item', $item);
      }

      // Only display the block if there are items to show.
      if (count($items) > 0) {
        $block['content'] = theme('item_list', $items) . $read_more;
      }
    }
    if (isset($block)) {
      return $block;
    }
  }
}

/**
 * Add/edit/delete aggregator categories.
 *
 * @param $edit
 *   An associative array describing the category to be added/edited/deleted.
 */
function aggregator_save_category($edit) {
  $link_path = 'aggregator/categories/';
  if (!empty($edit['cid'])) {
    $link_path .= $edit['cid'];
    if (!empty($edit['title'])) {
      db_merge('aggregator_category')
        ->key(array('cid' => $edit['cid']))
        ->fields(array(
          'title' => $edit['title'],
          'description' => $edit['description'],
        ))
        ->execute();
      $op = 'update';
    }
    else {
      db_delete('aggregator_category')
        ->condition('cid', $edit['cid'])
        ->execute();
      // Make sure there is no active block for this category.
      db_delete('blocks')
        ->condition('module', 'aggregator')
        ->condition('delta', 'category-' . $edit['cid'])
        ->execute();
      $edit['title'] = '';
      $op = 'delete';
    }
  }
  elseif (!empty($edit['title'])) {
    // A single unique id for bundles and feeds, to use in blocks.
    $link_path .= db_insert('aggregator_category')
      ->fields(array(
        'title' => $edit['title'],
        'description' => $edit['description'],
      ))
      ->execute();
    $op = 'insert';
  }
  if (isset($op)) {
    menu_link_maintain('aggregator', $op, $link_path, $edit['title']);
  }
}

/**
 * Add/edit/delete an aggregator feed.
 *
 * @param $edit
 *   An associative array describing the feed to be added/edited/deleted.
 */
function aggregator_save_feed($edit) {
  if (!empty($edit['fid'])) {
    // An existing feed is being modified, delete the category listings.
    db_delete('aggregator_category_feed')
      ->condition('fid', $edit['fid'])
      ->execute();
  }
  if (!empty($edit['fid']) && !empty($edit['title'])) {
    db_update('aggregator_feed')
      ->condition('fid', $edit['fid'])
      ->fields(array(
        'title' => $edit['title'],
        'url' => $edit['url'],
        'refresh' => $edit['refresh'],
        'block' => $edit['block'],
      ))
      ->execute();
  }
  elseif (!empty($edit['fid'])) {
    $iids = db_query('SELECT iid FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $edit['fid']))->fetchCol();
    if ($iids) {
      db_delete('aggregator_category_item')
        ->condition('iid', $iids, 'IN')
        ->execute();
    }
    db_delete('aggregator_feed')->
      condition('fid', $edit['fid'])
      ->execute();
    db_delete('aggregator_item')
      ->condition('fid', $edit['fid'])
      ->execute();
    // Make sure there is no active block for this feed.
    db_delete('blocks')
      ->condition('module', 'aggregator')
      ->condition('delta', 'feed-' . $edit['fid'])
      ->execute();
  }
  elseif (!empty($edit['title'])) {
    $edit['fid'] = db_insert('aggregator_feed')
      ->fields(array(
        'title' => $edit['title'],
        'url' => $edit['url'],
        'refresh' => $edit['refresh'],
        'block' => $edit['block'],
        'description' => '',
        'image' => '',
      ))
      ->execute();
    
  }
  if (!empty($edit['title'])) {
    // The feed is being saved, save the categories as well.
    if (!empty($edit['category'])) {
      foreach ($edit['category'] as $cid => $value) {
        if ($value) {
          db_merge('aggregator_category_feed')
            ->fields(array(
              'fid' => $edit['fid'],
              'cid' => $cid,
            ))
            ->execute();
        }
      }
    }
  }
}

/**
 * Removes all items from a feed.
 *
 * @param $feed
 *   An associative array describing the feed to be cleared.
 */
function aggregator_remove($feed) {
  $iids = db_query('SELECT iid FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed['fid']))->fetchCol();
  if ($iids) {
    db_delete('aggregator_category_item')
      ->condition('iid', $iids, 'IN')
      ->execute();
  }
  
  db_delete('aggregator_item')
    ->condition('fid', $feed['fid'])
    ->execute();
  db_merge('aggregator_feed')
    ->key(array('fid' => $feed['fid']))
    ->fields(array(
      'checked' => 0,
      'hash' => '',
      'modified' => 0,
      'description' => $feed['description'],
      'image' => $feed['image'],
    ))
    ->execute();
  drupal_set_message(t('The news items from %site have been removed.', array('%site' => $feed['title'])));
}

/**
 * Callback function used by the XML parser.
 */
function aggregator_element_start($parser, $name, $attributes) {
  global $item, $element, $tag, $items, $channel;

  switch ($name) {
    case 'IMAGE':
    case 'TEXTINPUT':
    case 'CONTENT':
    case 'SUMMARY':
    case 'TAGLINE':
    case 'SUBTITLE':
    case 'LOGO':
    case 'INFO':
      $element = $name;
      break;
    case 'ID':
      if ($element != 'ITEM') {
        $element = $name;
      }
    case 'LINK':
      if (!empty($attributes['REL']) && $attributes['REL'] == 'alternate') {
        if ($element == 'ITEM') {
          $items[$item]['LINK'] = $attributes['HREF'];
        }
        else {
          $channel['LINK'] = $attributes['HREF'];
        }
      }
      break;
    case 'ITEM':
      $element = $name;
      $item += 1;
      break;
    case 'ENTRY':
      $element = 'ITEM';
      $item += 1;
      break;
  }

  $tag = $name;
}

/**
 * Call-back function used by the XML parser.
 */
function aggregator_element_end($parser, $name) {
  global $element;

  switch ($name) {
    case 'IMAGE':
    case 'TEXTINPUT':
    case 'ITEM':
    case 'ENTRY':
    case 'CONTENT':
    case 'INFO':
      $element = '';
      break;
    case 'ID':
      if ($element == 'ID') {
        $element = '';
      }
  }
}

/**
 * Callback function used by the XML parser.
 */
function aggregator_element_data($parser, $data) {
  global $channel, $element, $items, $item, $image, $tag;
  $items += array($item => array());
  switch ($element) {
    case 'ITEM':
      $items[$item] += array($tag => '');
      $items[$item][$tag] .= $data;
      break;
    case 'IMAGE':
    case 'LOGO':
      $image += array($tag => '');
      $image[$tag] .= $data;
      break;
    case 'LINK':
      if ($data) {
        $items[$item] += array($tag => '');
        $items[$item][$tag] .= $data;
      }
      break;
    case 'CONTENT':
      $items[$item] += array('CONTENT' => '');
      $items[$item]['CONTENT'] .= $data;
      break;
    case 'SUMMARY':
      $items[$item] += array('SUMMARY' => '');
      $items[$item]['SUMMARY'] .= $data;
      break;
    case 'TAGLINE':
    case 'SUBTITLE':
      $channel += array('DESCRIPTION' => '');
      $channel['DESCRIPTION'] .= $data;
      break;
    case 'INFO':
    case 'ID':
    case 'TEXTINPUT':
      // The sub-element is not supported. However, we must recognize
      // it or its contents will end up in the item array.
      break;
    default:
      $channel += array($tag => '');
      $channel[$tag] .= $data;
  }
}

/**
 * Checks a news feed for new items.
 *
 * @param $feed
 *   An associative array describing the feed to be refreshed.
 */
function aggregator_refresh($feed) {
  global $channel, $image;

  // Generate conditional GET headers.
  $headers = array();
  if ($feed['etag']) {
    $headers['If-None-Match'] = $feed['etag'];
  }
  if ($feed['modified']) {
    $headers['If-Modified-Since'] = gmdate('D, d M Y H:i:s', $feed['modified']) . ' GMT';
  }

  // Request feed.
  $result = drupal_http_request($feed['url'], $headers);

  // Process HTTP response code.
  switch ($result->code) {
    case 304:
      db_update('aggregator_feed')
        ->fields(array('checked' => REQUEST_TIME))
        ->condition('fid', $feed['fid'])
        ->execute();
      drupal_set_message(t('There is no new syndicated content from %site.', array('%site' => $feed['title'])));
      break;
    case 301:
      $feed['url'] = $result->redirect_url;
      // Do not break here.
    case 200:
    case 302:
    case 307:
      // We store the md5 hash of feed data in the database. When refreshing a
      // feed we compare stored hash and new hash calculated from downloaded
      // data. If both are equal we say that feed is not updated.
      $md5 = md5($result->data);
      if ($feed['hash'] == $md5) {
        db_update('aggregator_feed')
          ->condition('fid', $feed['fid'])
          ->fields(array('checked' => REQUEST_TIME))
          ->execute();
        drupal_set_message(t('There is no new syndicated content from %site.', array('%site' => $feed['title'])));
        break;
      }

      // Filter the input data.
      if (aggregator_parse_feed($result->data, $feed)) {
        $modified = empty($result->headers['Last-Modified']) ? 0 : strtotime($result->headers['Last-Modified']);

        // Prepare the channel data.
        foreach ($channel as $key => $value) {
          $channel[$key] = trim($value);
        }

        // Prepare the image data (if any).
        foreach ($image as $key => $value) {
          $image[$key] = trim($value);
        }

        if (!empty($image['LINK']) && !empty($image['URL']) && !empty($image['TITLE'])) {
          $image = l(theme('image', $image['URL'], $image['TITLE']), $image['LINK'], array('html' => TRUE));
        }
        else {
          $image = '';
        }

        $etag = empty($result->headers['ETag']) ? '' : $result->headers['ETag'];
        // Update the feed data.
        db_merge('aggregator_feed')
          ->key(array('fid' => $feed['fid']))
          ->fields(array(
            'url' => $feed['url'],
            'checked' => REQUEST_TIME,
            'link' => $channel['LINK'],
            'description' => $channel['DESCRIPTION'],
            'image' => $image,
            'hash' => $md5,
            'etag' => $etag,
            'modified' => $modified,
          ))
          ->execute();

        // Clear the cache.
        cache_clear_all();

        if (isset($result->redirect_url)) {
          watchdog('aggregator', 'Updated URL for feed %title to %url.', array('%title' => $feed['title'], '%url' => $feed['url']));
        }

        watchdog('aggregator', 'There is new syndicated content from %site.', array('%site' => $feed['title']));
        drupal_set_message(t('There is new syndicated content from %site.', array('%site' => $feed['title'])));
      }
      break;
    default:
      watchdog('aggregator', 'The feed from %site seems to be broken, due to "%error".', array('%site' => $feed['title'], '%error' => $result->code . ' ' . $result->error), WATCHDOG_WARNING);
      drupal_set_message(t('The feed from %site seems to be broken, because of error "%error".', array('%site' => $feed['title'], '%error' => $result->code . ' ' . $result->error)));
      module_invoke('system', 'check_http_request');
  }
}

/**
 * Parse the W3C date/time format, a subset of ISO 8601.
 *
 * PHP date parsing functions do not handle this format.
 * See http://www.w3.org/TR/NOTE-datetime for more information.
 * Originally from MagpieRSS (http://magpierss.sourceforge.net/).
 *
 * @param $date_str
 *   A string with a potentially W3C DTF date.
 * @return
 *   A timestamp if parsed successfully or FALSE if not.
 */
function aggregator_parse_w3cdtf($date_str) {
  if (preg_match('/(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2})(:(\d{2}))?(?:([-+])(\d{2}):?(\d{2})|(Z))?/', $date_str, $match)) {
    list($year, $month, $day, $hours, $minutes, $seconds) = array($match[1], $match[2], $match[3], $match[4], $match[5], $match[6]);
    // Calculate the epoch for current date assuming GMT.
    $epoch = gmmktime($hours, $minutes, $seconds, $month, $day, $year);
    if ($match[10] != 'Z') { // Z is zulu time, aka GMT
      list($tz_mod, $tz_hour, $tz_min) = array($match[8], $match[9], $match[10]);
      // Zero out the variables.
      if (!$tz_hour) {
        $tz_hour = 0;
      }
      if (!$tz_min) {
        $tz_min = 0;
      }
      $offset_secs = (($tz_hour * 60) + $tz_min) * 60;
      // Is timezone ahead of GMT?  If yes, subtract offset.
      if ($tz_mod == '+') {
        $offset_secs *= -1;
      }
      $epoch += $offset_secs;
    }
    return $epoch;
  }
  else {
    return FALSE;
  }
}

/**
 * Parse a feed and store its items.
 *
 * @param $data
 *   The feed data.
 * @param $feed
 *   An associative array describing the feed to be parsed.
 * @return
 *   FALSE on error, TRUE otherwise.
 */
function aggregator_parse_feed(&$data, $feed) {
  global $items, $image, $channel;

  // Unset the global variables before we use them.
  unset($GLOBALS['element'], $GLOBALS['item'], $GLOBALS['tag']);
  $items = array();
  $image = array();
  $channel = array();

  // Parse the data.
  $xml_parser = drupal_xml_parser_create($data);
  xml_set_element_handler($xml_parser, 'aggregator_element_start', 'aggregator_element_end');
  xml_set_character_data_handler($xml_parser, 'aggregator_element_data');

  if (!xml_parse($xml_parser, $data, 1)) {
    watchdog('aggregator', 'The feed from %site seems to be broken, due to an error "%error" on line %line.', array('%site' => $feed['title'], '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser)), WATCHDOG_WARNING);
    drupal_set_message(t('The feed from %site seems to be broken, because of error "%error" on line %line.', array('%site' => $feed['title'], '%error' => xml_error_string(xml_get_error_code($xml_parser)), '%line' => xml_get_current_line_number($xml_parser))), 'error');
    return FALSE;
  }
  xml_parser_free($xml_parser);

  // We reverse the array such that we store the first item last, and the last
  // item first. In the database, the newest item should be at the top.
  $items = array_reverse($items);

  // Initialize variables.
  $title = $link = $author = $description = $guid = NULL;
  foreach ($items as $item) {
    unset($title, $link, $author, $description, $guid);

    // Prepare the item:
    foreach ($item as $key => $value) {
      $item[$key] = trim($value);
    }

    // Resolve the item's title. If no title is found, we use up to 40
    // characters of the description ending at a word boundary, but not
    // splitting potential entities.
    if (!empty($item['TITLE'])) {
      $title = $item['TITLE'];
    }
    elseif (!empty($item['DESCRIPTION'])) {
      $title = preg_replace('/^(.*)[^\w;&].*?$/', "\\1", truncate_utf8($item['DESCRIPTION'], 40));
    }
    else {
      $title = '';
    }

    // Resolve the items link.
    if (!empty($item['LINK'])) {
      $link = $item['LINK'];
    }
    else {
      $link = $feed['link'];
    }
    $guid = isset($item['GUID']) ? $item['GUID'] : '';

    // Atom feeds have a CONTENT and/or SUMMARY tag instead of a DESCRIPTION tag.
    if (!empty($item['CONTENT:ENCODED'])) {