Club Drupal

<?php

/**

 * @file

 * Drupal database update API.

 *

 * This file contains functions to perform database updates for a Drupal

 * installation. It is included and used extensively by update.php.

 */

/**

 * Minimum schema version of Drupal 6 required for upgrade to Drupal 7.

 *

 * Upgrades from Drupal 6 to Drupal 7 require that Drupal 6 be running

 * the most recent version, or the upgrade could fail. We can't easily

 * check the Drupal 6 version once the update process has begun, so instead

 * we check the schema version of system.module in the system table.

 */

define('REQUIRED_D6_SCHEMA_VERSION', '6055');

/**

 * Disable any items in the {system} table that are not core compatible.

 */

function update_fix_compatibility() {

  $incompatible = array();

  $result = db_query("SELECT name, type, status FROM {system} WHERE status = 1 AND type IN ('module','theme')");

  foreach ($result as $row) {

    if (update_check_incompatibility($row->name, $row->type)) {

      $incompatible[] = $row->name;

    }

  }

  if (!empty($incompatible)) {

    db_update('system')

      ->fields(array('status' => 0))

      ->condition('name', $incompatible, 'IN')

      ->execute();

  }

}

/**

 * Tests the compatibility of a module or theme.

 */

function update_check_incompatibility($name, $type = 'module') {

  static $themes, $modules;

  // Store values of expensive functions for future use.

  if (empty($themes) || empty($modules)) {

    // We need to do a full rebuild here to make sure the database reflects any

    // code changes that were made in the filesystem before the update script

    // was initiated.

    $themes = system_rebuild_theme_data();

    $modules = system_rebuild_module_data();

  }

  if ($type == 'module' && isset($modules[$name])) {

    $file = $modules[$name];

  }

  elseif ($type == 'theme' && isset($themes[$name])) {

    $file = $themes[$name];

  }

  if (!isset($file)

      || !isset($file->info['core'])

      || $file->info['core'] != DRUPAL_CORE_COMPATIBILITY

      || version_compare(phpversion(), $file->info['php']) < 0) {

    return TRUE;

  }

  return FALSE;

}

/**

 * Performs extra steps required to bootstrap when using a Drupal 6 database.

 *

 * Users who still have a Drupal 6 database (and are in the process of

 * updating to Drupal 7) need extra help before a full bootstrap can be

 * achieved. This function does the necessary preliminary work that allows

 * the bootstrap to be successful.

 *

 * No access check has been performed when this function is called, so no

 * irreversible changes to the database are made here.

 */

function update_prepare_d7_bootstrap() {

  // Allow the bootstrap to proceed even if a Drupal 6 settings.php file is

  // still being used.

  include_once DRUPAL_ROOT . '/includes/install.inc';

  drupal_bootstrap(DRUPAL_BOOTSTRAP_CONFIGURATION);

  global $databases, $db_url, $db_prefix, $update_rewrite_settings;

  if (empty($databases) && !empty($db_url)) {

    $databases = update_parse_db_url($db_url, $db_prefix);

    // Record the fact that the settings.php file will need to be rewritten.

    $update_rewrite_settings = TRUE;

    $settings_file = conf_path() . '/settings.php';

    $writable = drupal_verify_install_file($settings_file, FILE_EXIST|FILE_READABLE|FILE_WRITABLE);

    $requirements = array(

      'settings file' => array(

        'title' => 'Settings file',

        'value' => $writable ? 'The settings file is writable.' : 'The settings file is not writable.',

        'severity' => $writable ? REQUIREMENT_OK : REQUIREMENT_ERROR,

        'description' => $writable ? '' : 'Drupal requires write permissions to <em>' . $settings_file . '</em> during the update process. If you are unsure how to grant file permissions, consult the <a href="http://drupal.org/server-permissions">online handbook</a>.',

      ),

    );

    update_extra_requirements($requirements);

  }

  // The new {blocked_ips} table is used in Drupal 7 to store a list of

  // banned IP addresses. If this table doesn't exist then we are still

  // running on a Drupal 6 database, so we suppress the unavoidable errors

  // that occur by creating a static list.

  $GLOBALS['conf']['blocked_ips'] = array();

  // Check that PDO is available and that the correct PDO database driver is

  // loaded. Bootstrapping to DRUPAL_BOOTSTRAP_DATABASE will result in a fatal

  // error otherwise.

  $message = '';

  $pdo_link = 'http://drupal.org/requirements/pdo';

  // Check that PDO is loaded.

  if (!extension_loaded('pdo')) {

    $message = '<h2>PDO is required!</h2><p>Drupal 7 requires PHP ' . DRUPAL_MINIMUM_PHP . ' or higher with the PHP Data Objects (PDO) extension enabled.</p>';

  }

  // The PDO::ATTR_DEFAULT_FETCH_MODE constant is not available in the PECL

  // version of PDO.

  elseif (!defined('PDO::ATTR_DEFAULT_FETCH_MODE')) {

    $message = '<h2>The wrong version of PDO is installed!</h2><p>Drupal 7 requires the PHP Data Objects (PDO) extension from PHP core to be enabled. This system has the older PECL version installed.';

    $pdo_link = 'http://drupal.org/requirements/pdo#pecl';

  }

  // Check that the correct driver is loaded for the database being updated.

  // If we have no driver information (for example, if someone tried to create

  // the Drupal 7 $databases array themselves but did not do it correctly),

  // this message will be confusing, so do not perform the check; instead, just

  // let the database connection fail in the code that follows.

  elseif (isset($databases['default']['default']['driver']) && !in_array($databases['default']['default']['driver'], PDO::getAvailableDrivers())) {

    $message = '<h2>A PDO database driver is required!</h2><p>You need to enable the PDO_' . strtoupper($databases['default']['default']['driver']) . ' database driver for PHP ' . DRUPAL_MINIMUM_PHP . ' or higher so that Drupal 7 can access the database.</p>';

  }

  if ($message) {

    print $message . '<p>See the <a href="' . $pdo_link . '">system requirements page</a> for more information.</p>';

    exit();

  }

  // Allow the database system to work even if the registry has not been

  // created yet.

  drupal_bootstrap(DRUPAL_BOOTSTRAP_DATABASE);

  // If the site has not updated to Drupal 7 yet, check to make sure that it is

  // running an up-to-date version of Drupal 6 before proceeding. Note this has

  // to happen AFTER the database bootstraps because of

  // drupal_get_installed_schema_version().

  $system_schema = drupal_get_installed_schema_version('system');

  if ($system_schema < 7000) {

    $has_required_schema = $system_schema >= REQUIRED_D6_SCHEMA_VERSION;

    $requirements = array(

      'drupal 6 version' => array(

        'title' => 'Drupal 6 version',

        'value' => $has_required_schema ? 'You are running a current version of Drupal 6.' : 'You are not running a current version of Drupal 6',

        'severity' => $has_required_schema ? REQUIREMENT_OK : REQUIREMENT_ERROR,

        'description' => $has_required_schema ? '' : 'Please update your Drupal 6 installation to the most recent version before attempting to upgrade to Drupal 7',

      ),

    );

    // Make sure that the database environment is properly set up.

    try {

      db_run_tasks(db_driver());

    }

    catch (DatabaseTaskException $e) {

      $requirements['database tasks'] = array(

        'title' => 'Database environment',

        'value' => 'There is a problem with your database environment',

        'severity' => REQUIREMENT_ERROR,

        'description' => $e->getMessage(),

      );

    }

    update_extra_requirements($requirements);

    // Allow a D6 session to work, since the upgrade has not been performed yet.

    $d6_session_name = update_get_d6_session_name();

    if (!empty($_COOKIE[$d6_session_name])) {

      // Set the current sid to the one found in the D6 cookie.

      $sid = $_COOKIE[$d6_session_name];

      $_COOKIE[session_name()] = $sid;

      session_id($sid);

    }

    // Upgrading from D6 to D7.{0,1,2,3,4,8,...} is different than upgrading

    // from D6 to D7.{5,6,7} which should be considered broken. To be able to

    // properly handle this difference in node_update_7012 we need to keep track

    // of whether a D6 > D7 upgrade or a D7 > D7 update is running.

    // Since variable_set() is not available here, the D6 status is being saved

    // in a local variable to be able to store it later.

    $update_d6 = TRUE;

  }

  // Create the registry tables.

  if (!db_table_exists('registry')) {

    $schema['registry'] = array(

      'fields' => array(

        'name'   => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''),

        'type'   => array('type' => 'varchar', 'length' => 9, 'not null' => TRUE, 'default' => ''),

        'filename'   => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''),

        'module'   => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''),

        'weight'   => array('type' => 'int', 'not null' => TRUE, 'default' => 0),

      ),

      'primary key' => array('name', 'type'),

      'indexes' => array(

        'hook' => array('type', 'weight', 'module'),

      ),

    );

    db_create_table('registry', $schema['registry']);

  }

  if (!db_table_exists('registry_file')) {

    $schema['registry_file'] = array(

      'fields' => array(

        'filename'   => array('type' => 'varchar', 'length' => 255, 'not null' => TRUE),

        'hash'   => array('type' => 'varchar', 'length' => 64, 'not null' => TRUE),

      ),

      'primary key' => array('filename'),

    );

    db_create_table('registry_file', $schema['registry_file']);

  }

  // Older versions of Drupal 6 do not include the semaphore table, which is

  // required to bootstrap, so we add it now so that we can bootstrap and

  // provide a reasonable error message.

  if (!db_table_exists('semaphore')) {

    $semaphore = array(

      'description' => 'Table for holding semaphores, locks, flags, etc. that cannot be stored as Drupal variables since they must not be cached.',

      'fields' => array(

        'name' => array(

          'description' => 'Primary Key: Unique name.',

          'type' => 'varchar',

          'length' => 255,

          'not null' => TRUE,

          'default' => ''

        ),

        'value' => array(

          'description' => 'A value for the semaphore.',

          'type' => 'varchar',

          'length' => 255,

          'not null' => TRUE,

          'default' => ''

        ),

        'expire' => array(

          'description' => 'A Unix timestamp with microseconds indicating when the semaphore should expire.',

          'type' => 'float',

          'size' => 'big',

          'not null' => TRUE

        ),

      ),

      'indexes' => array(

        'value' => array('value'),

        'expire' => array('expire'),

      ),

      'primary key' => array('name'),

    );

    db_create_table('semaphore', $semaphore);

  }

  // The new cache_bootstrap bin is required to bootstrap to

  // DRUPAL_BOOTSTRAP_SESSION, so create it here rather than in

  // update_fix_d7_requirements().

  if (!db_table_exists('cache_bootstrap')) {

    $cache_bootstrap = array(

      'description' => 'Cache table for data required to bootstrap Drupal, may be routed to a shared memory cache.',

      'fields' => array(

        'cid' => array(

          'description' => 'Primary Key: Unique cache ID.',

          'type' => 'varchar',

          'length' => 255,

          'not null' => TRUE,

          'default' => '',

        ),

        'data' => array(

          'description' => 'A collection of data to cache.',

          'type' => 'blob',

          'not null' => FALSE,

          'size' => 'big',

        ),

        'expire' => array(

          'description' => 'A Unix timestamp indicating when the cache entry should expire, or 0 for never.',

          'type' => 'int',

          'not null' => TRUE,

          'default' => 0,

        ),

        'created' => array(

          'description' => 'A Unix timestamp indicating when the cache entry was created.',

          'type' => 'int',

          'not null' => TRUE,

          'default' => 0,

        ),

        'serialized' => array(

          'description' => 'A flag to indicate whether content is serialized (1) or not (0).',

          'type' => 'int',

          'size' => 'small',

          'not null' => TRUE,

          'default' => 0,

        ),

      ),

      'indexes' => array(

        'expire' => array('expire'),

      ),

      'primary key' => array('cid'),

    );

    db_create_table('cache_bootstrap', $cache_bootstrap);

  }

  // Set a valid timezone for 6 -> 7 upgrade process.

  drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES);

  $timezone_offset = variable_get('date_default_timezone', 0);

  if (is_numeric($timezone_offset)) {

    // Save the original offset.

    variable_set('date_temporary_timezone', $timezone_offset);

    // Set the timezone for this request only.

    $GLOBALS['conf']['date_default_timezone'] = 'UTC';

  }

  // This allows update functions to tell if an upgrade from D6 is running.

  if (!empty($update_d6)) {

    variable_set('update_d6', TRUE);

  }

}

/**

 * A helper function that modules can use to assist with the transformation

 * from numeric block deltas to string block deltas during the 6.x -> 7.x

 * upgrade.

 *

 * @todo This function should be removed in 8.x.

 *

 * @param $sandbox

 *   An array holding data for the batch process.

 * @param $renamed_deltas

 *   An associative array.  Keys are module names, values an associative array

 *   mapping the old block deltas to the new block deltas for the module.

 *   Example:

 *   @code

 *     $renamed_deltas = array(

 *       'mymodule' =>

 *         array(

 *           0 => 'mymodule-block-1',

 *           1 => 'mymodule-block-2',

 *         ),

 *     );

 *   @endcode

 * @param $moved_deltas

 *   An associative array. Keys are source module names, values an associative

 *   array mapping the (possibly renamed) block name to the new module name.

 *   Example:

 *   @code

 *     $moved_deltas = array(

 *       'user' =>

 *         array(

 *           'navigation' => 'system',

 *         ),

 *     );

 *   @endcode

 */

function update_fix_d7_block_deltas(&$sandbox, $renamed_deltas, $moved_deltas) {

  // Loop through each block and make changes to the block tables.

  // Only run this the first time through the batch update.

  if (!isset($sandbox['progress'])) {

    // Determine whether to use the old or new block table names.

    $block_tables = db_table_exists('blocks') ? array('blocks', 'blocks_roles') : array('block', 'block_role');

    foreach ($block_tables as $table) {

      foreach ($renamed_deltas as $module => $deltas) {

        foreach ($deltas as $old_delta => $new_delta) {

          // Only do the update if the old block actually exists.

          $block_exists = db_query("SELECT COUNT(*) FROM {" . $table . "} WHERE module = :module AND delta = :delta", array(

              ':module' => $module,

              ':delta' => $old_delta,

            ))

            ->fetchField();

          if ($block_exists) {

            // Delete any existing blocks with the new module+delta.

            db_delete($table)

              ->condition('module', $module)

              ->condition('delta', $new_delta)

              ->execute();

            // Rename the old block to the new module+delta.

            db_update($table)

              ->fields(array('delta' => $new_delta))

              ->condition('module', $module)

              ->condition('delta', $old_delta)

              ->execute();

          }

        }

      }

      foreach ($moved_deltas as $old_module => $deltas) {

        foreach ($deltas as $delta => $new_module) {

          // Only do the update if the old block actually exists.

          $block_exists = db_query("SELECT COUNT(*) FROM {" . $table . "} WHERE module = :module AND delta = :delta", array(

              ':module' => $old_module,

              ':delta' => $delta,

            ))

            ->fetchField();

          if ($block_exists) {

            // Delete any existing blocks with the new module+delta.

            db_delete($table)

              ->condition('module', $new_module)

              ->condition('delta', $delta)

              ->execute();

            // Rename the old block to the new module+delta.

            db_update($table)

              ->fields(array('module' => $new_module))

              ->condition('module', $old_module)

              ->condition('delta', $delta)

              ->execute();

          }

        }

      }

    }

    // Initialize batch update information.

    $sandbox['progress'] = 0;

    $sandbox['last_user_processed'] = -1;

    $sandbox['max'] = db_query("SELECT COUNT(*) FROM {users} WHERE data LIKE :block", array(

        ':block' => '%' . db_like(serialize('block')) . '%',

      ))

      ->fetchField();

  }

  // Now do the batch update of the user-specific block visibility settings.

  $limit = 100;

  $result = db_select('users', 'u')

    ->fields('u', array('uid', 'data'))

    ->condition('uid', $sandbox['last_user_processed'], '>')

    ->condition('data', '%' . db_like(serialize('block')) . '%', 'LIKE')

    ->orderBy('uid', 'ASC')

    ->range(0, $limit)

    ->execute();

  foreach ($result as $row) {

    $data = unserialize($row->data);

    $user_needs_update = FALSE;

    foreach ($renamed_deltas as $module => $deltas) {

      foreach ($deltas as $old_delta => $new_delta) {

        if (isset($data['block'][$module][$old_delta])) {

          // Transfer the old block visibility settings to the newly-renamed

          // block, and mark this user for a database update.

          $data['block'][$module][$new_delta] = $data['block'][$module][$old_delta];

          unset($data['block'][$module][$old_delta]);

          $user_needs_update = TRUE;

        }

      }

    }

    foreach ($moved_deltas as $old_module => $deltas) {

      foreach ($deltas as $delta => $new_module) {

        if (isset($data['block'][$old_module][$delta])) {

          // Transfer the old block visibility settings to the moved

          // block, and mark this user for a database update.

          $data['block'][$new_module][$delta] = $data['block'][$old_module][$delta];

          unset($data['block'][$old_module][$delta]);

          $user_needs_update = TRUE;

        }

      }

    }

    // Update the current user.

    if ($user_needs_update) {

      db_update('users')

        ->fields(array('data' => serialize($data)))

        ->condition('uid', $row->uid)

        ->execute();

    }

    // Update our progress information for the batch update.

    $sandbox['progress']++;

    $sandbox['last_user_processed'] = $row->uid;

  }

  // Indicate our current progress to the batch update system.

  if ($sandbox['progress'] < $sandbox['max']) {

    $sandbox['#finished'] = $sandbox['progress'] / $sandbox['max'];

  }

}

/**

 * Perform Drupal 6.x to 7.x updates that are required for update.php

 * to function properly.

 *

 * This function runs when update.php is run the first time for 7.x,

 * even before updates are selected or performed. It is important

 * that if updates are not ultimately performed that no changes are

 * made which make it impossible to continue using the prior version.

 */

function update_fix_d7_requirements() {

  global $conf;

  // Rewrite the settings.php file if necessary, see

  // update_prepare_d7_bootstrap().

  global $update_rewrite_settings, $db_url, $db_prefix;

  if (!empty($update_rewrite_settings)) {

    $databases = update_parse_db_url($db_url, $db_prefix);

    $salt = drupal_hash_base64(drupal_random_bytes(55));

    file_put_contents(conf_path() . '/settings.php', "\n" . '$databases = ' . var_export($databases, TRUE) . ";\n\$drupal_hash_salt = '$salt';", FILE_APPEND);

  }

  if (drupal_get_installed_schema_version('system') < 7000 && !variable_get('update_d7_requirements', FALSE)) {

    // Change 6.x system table field values to 7.x equivalent.

    // Change field values.

    db_change_field('system', 'schema_version', 'schema_version', array(

     'type' => 'int',

     'size' => 'small',

     'not null' => TRUE,

     'default' => -1)

    );

    db_change_field('system', 'status', 'status', array(

      'type' => 'int', 'not null' => TRUE, 'default' => 0));

    db_change_field('system', 'weight', 'weight', array(

      'type' => 'int', 'not null' => TRUE, 'default' => 0));

    db_change_field('system', 'bootstrap', 'bootstrap', array(

      'type' => 'int', 'not null' => TRUE, 'default' => 0));

    // Drop and recreate 6.x indexes.

    db_drop_index('system', 'bootstrap');

    db_add_index('system', 'bootstrap', array(

      'status', 'bootstrap', array('type', 12), 'weight', 'name'));

    db_drop_index('system' ,'modules');

    db_add_index('system', 'modules', array(array(

      'type', 12), 'status', 'weight', 'name'));

    db_drop_index('system', 'type_name');

    db_add_index('system', 'type_name', array(array('type', 12), 'name'));

    // Add 7.x indexes.

    db_add_index('system', 'system_list', array('weight', 'name'));

    // Add the cache_path table.

    if (db_table_exists('cache_path')) {

      db_drop_table('cache_path');

    }

    require_once('./modules/system/system.install');

    $schema['cache_path'] = system_schema_cache_7054();

    $schema['cache_path']['description'] = 'Cache table used for path alias lookups.';

    db_create_table('cache_path', $schema['cache_path']);

    // system_update_7042() renames columns, but these are needed to bootstrap.

    // Add empty columns for now.

    db_add_field('url_alias', 'source', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''));

    db_add_field('url_alias', 'alias', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''));

    // Add new columns to {menu_router}.

    db_add_field('menu_router', 'delivery_callback', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''));

    db_add_field('menu_router', 'context', array(

      'description' => 'Only for local tasks (tabs) - the context of a local task to control its placement.',

      'type' => 'int',

      'not null' => TRUE,

      'default' => 0,

    ));

    db_drop_index('menu_router', 'tab_parent');

    db_add_index('menu_router', 'tab_parent', array(array('tab_parent', 64), 'weight', 'title'));

    db_add_field('menu_router', 'theme_callback', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''));

    db_add_field('menu_router', 'theme_arguments', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => ''));

    // Add the role_permission table.

    $schema['role_permission'] = array(

      'fields' => array(

        'rid' => array(

        'type' => 'int',

        'unsigned' => TRUE,

        'not null' => TRUE,

      ),

      'permission' => array(

        'type' => 'varchar',

        'length' => 128,

        'not null' => TRUE,

        'default' => '',

      ),

    ),

    'primary key' => array('rid', 'permission'),

    'indexes' => array(

      'permission' => array('permission'),

      ),

    );

    db_create_table('role_permission', $schema['role_permission']);

    // Drops and recreates semaphore value index.

    db_drop_index('semaphore', 'value');

    db_add_index('semaphore', 'value', array('value'));

    $schema['date_format_type'] = array(

      'description' => 'Stores configured date format types.',

      'fields' => array(

        'type' => array(

          'description' => 'The date format type, e.g. medium.',

          'type' => 'varchar',

          'length' => 64,

          'not null' => TRUE,

        ),

        'title' => array(

          'description' => 'The human readable name of the format type.',

          'type' => 'varchar',

          'length' => 255,

          'not null' => TRUE,

        ),

        'locked' => array(

          'description' => 'Whether or not this is a system provided format.',

          'type' => 'int',

          'size' => 'tiny',

          'default' => 0,

          'not null' => TRUE,

        ),

      ),

      'primary key' => array('type'),

    );

    $schema['date_formats'] = array(

      'description' => 'Stores configured date formats.',

      'fields' => array(

        'dfid' => array(

          'description' => 'The date format identifier.',

          'type' => 'serial',

          'not null' => TRUE,

          'unsigned' => TRUE,

        ),

        'format' => array(

          'description' => 'The date format string.',

          'type' => 'varchar',

          'length' => 100,

          'not null' => TRUE,

        ),

        'type' => array(

          'description' => 'The date format type, e.g. medium.',

          'type' => 'varchar',

          'length' => 64,

          'not null' => TRUE,

        ),

        'locked' => array(

          'description' => 'Whether or not this format can be modified.',

          'type' => 'int',

          'size' => 'tiny',

          'default' => 0,

          'not null' => TRUE,

        ),

      ),

      'primary key' => array('dfid'),

      'unique keys' => array('formats' => array('format', 'type')),

    );

    $schema['date_format_locale'] = array(

      'description' => 'Stores configured date formats for each locale.',

      'fields' => array(

        'format' => array(

          'description' => 'The date format string.',

          'type' => 'varchar',

          'length' => 100,

          'not null' => TRUE,

        ),

        'type' => array(

          'description' => 'The date format type, e.g. medium.',

          'type' => 'varchar',

          'length' => 64,

          'not null' => TRUE,

        ),

        'language' => array(

          'description' => 'A {languages}.language for this format to be used with.',

          'type' => 'varchar',

          'length' => 12,

          'not null' => TRUE,

        ),

      ),

      'primary key' => array('type', 'language'),

    );

    db_create_table('date_format_type', $schema['date_format_type']);

    // Sites that have the Drupal 6 Date module installed already have the

    // following tables.

    if (db_table_exists('date_formats')) {

      db_rename_table('date_formats', 'd6_date_formats');

    }

    db_create_table('date_formats', $schema['date_formats']);

    if (db_table_exists('date_format_locale')) {

      db_rename_table('date_format_locale', 'd6_date_format_locale');

    }

    db_create_table('date_format_locale', $schema['date_format_locale']);

    // Add the queue table.

    $schema['queue'] = array(

      'description' => 'Stores items in queues.',

      'fields' => array(

        'item_id' => array(

          'type' => 'serial',

          'unsigned' => TRUE,

          'not null' => TRUE,

          'description' => 'Primary Key: Unique item ID.',

        ),

        'name' => array(

          'type' => 'varchar',

          'length' => 255,

          'not null' => TRUE,

          'default' => '',

          'description' => 'The queue name.',

        ),

        'data' => array(

          'type' => 'blob',

          'not null' => FALSE,

          'size' => 'big',

          'serialize' => TRUE,

          'description' => 'The arbitrary data for the item.',

        ),

        'expire' => array(

          'type' => 'int',

          'not null' => TRUE,

          'default' => 0,

          'description' => 'Timestamp when the claim lease expires on the item.',

        ),

        'created' => array(

          'type' => 'int',

          'not null' => TRUE,

          'default' => 0,

          'description' => 'Timestamp when the item was created.',

        ),

      ),

      'primary key' => array('item_id'),

      'indexes' => array(

        'name_created' => array('name', 'created'),

        'expire' => array('expire'),

      ),

    );

    // Check for queue table that may remain from D5 or D6, if found

    //drop it.

    if (db_table_exists('queue')) {

      db_drop_table('queue');

    }

    db_create_table('queue', $schema['queue']);

    // Create the sequences table.

    $schema['sequences'] = array(

      'description' => 'Stores IDs.',

      'fields' => array(

        'value' => array(

          'description' => 'The value of the sequence.',

          'type' => 'serial',

          'unsigned' => TRUE,

          'not null' => TRUE,

        ),

       ),

      'primary key' => array('value'),

    );

    // Check for sequences table that may remain from D5 or D6, if found

    //drop it.

    if (db_table_exists('sequences')) {

      db_drop_table('sequences');

    }

    db_create_table('sequences', $schema['sequences']);

    // Initialize the table with the maximum current increment of the tables

    // that will rely on it for their ids.

    $max_aid = db_query('SELECT MAX(aid) FROM {actions_aid}')->fetchField();

    $max_uid = db_query('SELECT MAX(uid) FROM {users}')->fetchField();

    $max_batch_id = db_query('SELECT MAX(bid) FROM {batch}')->fetchField();

    db_insert('sequences')->fields(array('value' => max($max_aid, $max_uid, $max_batch_id)))->execute();

    // Add column for locale context.

    if (db_table_exists('locales_source')) {

      db_add_field('locales_source', 'context', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => '', 'description' => 'The context this string applies to.'));

    }

    // Rename 'site_offline_message' variable to 'maintenance_mode_message'

    // and 'site_offline' variable to 'maintenance_mode'.

    // Old variable is removed in update for system.module, see

    // system_update_7072().

    if ($message = variable_get('site_offline_message', NULL)) {

      variable_set('maintenance_mode_message', $message);

    }

    // Old variable is removed in update for system.module, see

    // system_update_7069().

    $site_offline = variable_get('site_offline', -1);

    if ($site_offline != -1) {

      variable_set('maintenance_mode', $site_offline);

    }

    // Add ssid column and index.

    db_add_field('sessions', 'ssid', array('description' => "Secure session ID. The value is generated by Drupal's session handlers.", 'type' => 'varchar', 'length' => 128, 'not null' => TRUE, 'default' => ''));

    db_add_index('sessions', 'ssid', array('ssid'));

    // Drop existing primary key.

    db_drop_primary_key('sessions');

    // Add new primary key.

    db_add_primary_key('sessions', array('sid', 'ssid'));

    // Allow longer javascript file names.

    if (db_table_exists('languages')) {

      db_change_field('languages', 'javascript', 'javascript', array('type' => 'varchar', 'length' => 64, 'not null' => TRUE, 'default' => ''));

    }

    // Rename action description to label.

    db_change_field('actions', 'description', 'label', array('type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => '0'));

    variable_set('update_d7_requirements', TRUE);

  }

  update_fix_d7_install_profile();

}

/**

 * Register the currently installed profile in the system table.

 *

 * Installation profiles are now treated as modules by Drupal, and have an

 * upgrade path based on their schema version in the system table.

 *

 * The installation profile will be set to schema_version 0, as it has already

 * been installed. Any other hook_update_N functions provided by the

 * installation profile will be run by update.php.

 */

function update_fix_d7_install_profile() {

  $profile = drupal_get_profile();

  // 'Default' profile has been renamed to 'Standard' in D7.

  // We change the profile here to prevent a broken record in the system table.

  // See system_update_7049().

  if ($profile == 'default') {

    $profile = 'standard';

    variable_set('install_profile', $profile);

  }

  $results = db_select('system', 's')

    ->fields('s', array('name', 'schema_version'))

    ->condition('name', $profile)

    ->condition('type', 'module')

    ->execute()

    ->fetchAll();

  if (empty($results)) {

    $filename = 'profiles/' . $profile . '/' . $profile . '.profile';

    // Read profile info file

    $info = drupal_parse_info_file(dirname($filename) . '/' . $profile . '.info');

    // Merge in defaults.

    $info = $info + array(

      'dependencies' => array(),

      'description' => '',

      'package' => 'Other',

      'version' => NULL,

      'php' => DRUPAL_MINIMUM_PHP,

      'files' => array(),

    );

    $values = array(

      'filename' => $filename,

      'name' => $profile,

      'info' => serialize($info),

      'schema_version' => 0,

      'type' => 'module',

      'status' => 1,

      'owner' => '',

    );

    // Installation profile hooks are always executed last by the module system

    $values['weight'] = 1000;

    // Initializing the system table entry for the installation profile

    db_insert('system')

      ->fields(array_keys($values))

      ->values($values)

      ->execute();

    // Reset the cached schema version.

    drupal_get_installed_schema_version($profile, TRUE);

    // Load the updates again to make sure the installation profile updates

    // are loaded.

    drupal_load_updates();

  }

}

/**

 * Parse pre-Drupal 7 database connection URLs and return D7 compatible array.

 *

 * @return

 *   Drupal 7 DBTNG compatible array of database connection information.

 */

function update_parse_db_url($db_url, $db_prefix) {

  $databases = array();

  if (!is_array($db_url)) {

    $db_url = array('default' => $db_url);

  }

  foreach ($db_url as $database => $url) {

    $url = parse_url($url);

    $databases[$database]['default'] = array(

      // MySQLi uses the mysql driver.

      'driver' => $url['scheme'] == 'mysqli' ? 'mysql' : $url['scheme'],

      // Remove the leading slash to get the database name.

      'database' => substr(urldecode($url['path']), 1),

      'username' => urldecode($url['user']),

      'password' => isset($url['pass']) ? urldecode($url['pass']) : '',

      'host' => urldecode($url['host']),

      'port' => isset($url['port']) ? urldecode($url['port']) : '',

    );

    if (isset($db_prefix)) {

      $databases[$database]['default']['prefix'] = $db_prefix;

    }

  }

  return $databases;

}

/**

 * Constructs a session name compatible with a D6 environment.

 *

 * @return

 *   D6-compatible session name string.

 *

 * @see drupal_settings_initialize()

 */

function update_get_d6_session_name() {

  global $base_url, $cookie_domain;

  $cookie_secure = ini_get('session.cookie_secure');

  // If a custom cookie domain is set in settings.php, that variable forms

  // the basis of the session name. Re-compute the D7 hashing method to find

  // out if $cookie_domain was used as the session name.

  if (($cookie_secure ? 'SSESS' : 'SESS') . substr(hash('sha256', $cookie_domain), 0, 32) == session_name()) {

    $session_name = $cookie_domain;

  }

  else {

    // Otherwise use $base_url as session name, without the protocol

    // to use the same session identifiers across HTTP and HTTPS.

    list( , $session_name) = explode('://', $base_url, 2);

  }

  if ($cookie_secure) {

    $session_name .= 'SSL';

  }

  return 'SESS' . md5($session_name);

}

/**

 * Implements callback_batch_operation().

 *

 * Performs one update and stores the results for display on the results page.

 *

 * If an update function completes successfully, it should return a message

 * as a string indicating success, for example:

 * @code

 * return t('New index added successfully.');

 * @endcode

 *

 * Alternatively, it may return nothing. In that case, no message

 * will be displayed at all.

 *

 * If it fails for whatever reason, it should throw an instance of

 * DrupalUpdateException with an appropriate error message, for example:

 * @code

 * throw new DrupalUpdateException(t('Description of what went wrong'));

 * @endcode

 *

 * If an exception is thrown, the current update and all updates that depend on

 * it will be aborted. The schema version will not be updated in this case, and

 * all the aborted updates will continue to appear on update.php as updates

 * that have not yet been run.

 *

 * If an update function needs to be re-run as part of a batch process, it

 * should accept the $sandbox array by reference as its first parameter

 * and set the #finished property to the percentage completed that it is, as a

 * fraction of 1.

 *

 * @param $module

 *   The module whose update will be run.

 * @param $number

 *   The update number to run.

 * @param $dependency_map

 *   An array whose keys are the names of all update functions that will be

 *   performed during this batch process, and whose values are arrays of other

 *   update functions that each one depends on.

 * @param $context

 *   The batch context array.

 *

 * @see update_resolve_dependencies()

 */

function update_do_one($module, $number, $dependency_map, &$context) {

  $function = $module . '_update_' . $number;

  // If this update was aborted in a previous step, or has a dependency that

  // was aborted in a previous step, go no further.

  if (!empty($context['results']['#abort']) && array_intersect($context['results']['#abort'], array_merge($dependency_map, array($function)))) {

    return;

  }

  $ret = array();

  if (function_exists($function)) {

    try {

      $ret['results']['query'] = $function($context['sandbox']);

      $ret['results']['success'] = TRUE;

    }

    // @TODO We may want to do different error handling for different

    // exception types, but for now we'll just log the exception and

    // return the message for printing.

    catch (Exception $e) {

      watchdog_exception('update', $e);

      require_once DRUPAL_ROOT . '/includes/errors.inc';

      $variables = _drupal_decode_exception($e);

      // The exception message is run through check_plain() by _drupal_decode_exception().

      $ret['#abort'] = array('success' => FALSE, 'query' => t('%type: !message in %function (line %line of %file).', $variables));

    }

  }

  if (isset($context['sandbox']['#finished'])) {

    $context['finished'] = $context['sandbox']['#finished'];

    unset($context['sandbox']['#finished']);

  }

  if (!isset($context['results'][$module])) {

    $context['results'][$module] = array();

  }

  if (!isset($context['results'][$module][$number])) {

    $context['results'][$module][$number] = array();

  }

  $context['results'][$module][$number] = array_merge($context['results'][$module][$number], $ret);

  if (!empty($ret['#abort'])) {

    // Record this function in the list of updates that were aborted.

    $context['results']['#abort'][] = $function;

  }

  // Record the schema update if it was completed successfully.

  if ($context['finished'] == 1 && empty($ret['#abort'])) {

    drupal_set_installed_schema_version($module, $number);

  }

  $context['message'] = 'Updating ' . check_plain($module) . ' module';

}

/**

 * @class Exception class used to throw error if a module update fails.

 */

class DrupalUpdateException extends Exception { }

/**

 * Starts the database update batch process.

 *

 * @param $start

 *   An array whose keys contain the names of modules to be updated during the

 *   current batch process, and whose values contain the number of the first

 *   requested update for that module. The actual updates that are run (and the

 *   order they are run in) will depend on the results of passing this data

 *   through the update dependency system.

 * @param $redirect

 *   Path to redirect to when the batch has finished processing.

 * @param $url

 *   URL of the batch processing page (should only be used for separate

 *   scripts like update.php).

 * @param $batch

 *   Optional parameters to pass into the batch API.

 * @param $redirect_callback

 *   (optional) Specify a function to be called to redirect to the progressive

 *   processing page.

 *

 * @see update_resolve_dependencies()

 */

function update_batch($start, $redirect = NULL, $url = NULL, $batch = array(), $redirect_callback = 'drupal_goto') {

  // During the update, bring the site offline so that schema changes do not

  // affect visiting users.

  $_SESSION['maintenance_mode'] = variable_get('maintenance_mode', FALSE);

  if ($_SESSION['maintenance_mode'] == FALSE) {

    variable_set('maintenance_mode', TRUE);

  }

  // Resolve any update dependencies to determine the actual updates that will

  // be run and the order they will be run in.

  $updates = update_resolve_dependencies($start);

  // Store the dependencies for each update function in an array which the

  // batch API can pass in to the batch operation each time it is called. (We

  // do not store the entire update dependency array here because it is

  // potentially very large.)

  $dependency_map = array();

  foreach ($updates as $function => $update) {

    $dependency_map[$function] = !empty($update['reverse_paths']) ? array_keys($update['reverse_paths']) : array();

  }

  $operations = array();

  foreach ($updates as $update) {

    if ($update['allowed']) {

      // Set the installed version of each module so updates will start at the

      // correct place. (The updates are already sorted, so we can simply base

      // this on the first one we come across in the above foreach loop.)

      if (isset($start[$update['module']])) {

        drupal_set_installed_schema_version($update['module'], $update['number'] - 1);

        unset($start[$update['module']]);

      }

      // Add this update function to the batch.

      $function = $update['module'] . '_update_' . $update['number'];

      $operations[] = array('update_do_one', array($update['module'], $update['number'], $dependency_map[$function]));

    }

  }

  $batch['operations'] = $operations;

  $batch += array(

    'title' => 'Updating',

    'init_message' => 'Starting updates',

    'error_message' => 'An unrecoverable error has occurred. You can find the error message below. It is advised to copy it to the clipboard for reference.',

    'finished' => 'update_finished',

    'file' => 'includes/update.inc',

  );

  batch_set($batch);

  batch_process($redirect, $url, $redirect_callback);

}

/**

 * Implements callback_batch_finished().

 *

 * Finishes the update process and stores the results for eventual display.

 *

 * After the updates run, all caches are flushed. The update results are

 * stored into the session (for example, to be displayed on the update results

 * page in update.php). Additionally, if the site was off-line, now that the

 * update process is completed, the site is set back online.

 *

 * @param $success

 *   Indicate that the batch API tasks were all completed successfully.

 * @param $results

 *   An array of all the results that were updated in update_do_one().

 * @param $operations

 *   A list of all the operations that had not been completed by the batch API.

 *

 * @see update_batch()

 */

function update_finished($success, $results, $operations) {

  // Remove the D6 upgrade flag variable so that subsequent update runs do not

  // get the wrong context.

  variable_del('update_d6');

  // Clear the caches in case the data has been updated.

  drupal_flush_all_caches();

  $_SESSION['update_results'] = $results;

  $_SESSION['update_success'] = $success;

  $_SESSION['updates_remaining'] = $operations;

  // Now that the update is done, we can put the site back online if it was

  // previously in maintenance mode.

  if (isset($_SESSION['maintenance_mode']) && $_SESSION['maintenance_mode'] == FALSE) {

    variable_set('maintenance_mode', FALSE);

    unset($_SESSION['maintenance_mode']);

  }

}

/**

 * Returns a list of all the pending database updates.

 *

 * @return

 *   An associative array keyed by module name which contains all information

 *   about database updates that need to be run, and any updates that are not

 *   going to proceed due to missing requirements. The system module will

 *   always be listed first.

 *

 *   The subarray for each module can contain the following keys:

 *   - start: The starting update that is to be processed. If this does not

 *       exist then do not process any updates for this module as there are

 *       other requirements that need to be resolved.

 *   - warning: Any warnings about why this module can not be updated.

 *   - pending: An array of all the pending updates for the module including

 *       the update number and the description from source code comment for

 *       each update function. This array is keyed by the update number.

 */

function update_get_update_list() {

  // Make sure that the system module is first in the list of updates.

  $ret = array('system' => array());

  $modules = drupal_get_installed_schema_version(NULL, FALSE, TRUE);

  foreach ($modules as $module => $schema_version) {

    // Skip uninstalled and incompatible modules.

    if ($schema_version == SCHEMA_UNINSTALLED || update_check_incompatibility($module)) {

      continue;

    }

    // Otherwise, get the list of updates defined by this module.

    $updates = drupal_get_schema_versions($module);

    if ($updates !== FALSE) {

      // module_invoke returns NULL for nonexisting hooks, so if no updates

      // are removed, it will == 0.

      $last_removed = module_invoke($module, 'update_last_removed');

      if ($schema_version < $last_removed) {

        $ret[$module]['warning'] = '<em>' . $module . '</em> module can not be updated. Its schema version is ' . $schema_version . '. Updates up to and including ' . $last_removed . ' have been removed in this release. In order to update <em>' . $module . '</em> module, you will first <a href="http://drupal.org/upgrade">need to upgrade</a> to the last version in which these updates were available.';

        continue;

      }

      $updates = drupal_map_assoc($updates);

      foreach (array_keys($updates) as $update) {

        if ($update > $schema_version) {

          // The description for an update comes from its Doxygen.

          $func = new ReflectionFunction($module . '_update_' . $update);

          $description = str_replace(array("\n", '*', '/'), '', $func->getDocComment());

          $ret[$module]['pending'][$update] = "$update - $description";

          if (!isset($ret[$module]['start'])) {

            $ret[$module]['start'] = $update;

          }

        }

      }

      if (!isset($ret[$module]['start']) && isset($ret[$module]['pending'])) {

        $ret[$module]['start'] = $schema_version;

      }

    }

  }

  if (empty($ret['system'])) {

    unset($ret['system']);

  }

  return $ret;

}

/**

 * Resolves dependencies in a set of module updates, and orders them correctly.

 *

 * This function receives a list of requested module updates and determines an

 * appropriate order to run them in such that all update dependencies are met.

 * Any updates whose dependencies cannot be met are included in the returned

 * array but have the key 'allowed' set to FALSE; the calling function should

 * take responsibility for ensuring that these updates are ultimately not

 * performed.

 *

 * In addition, the returned array also includes detailed information about the

 * dependency chain for each update, as provided by the depth-first search

 * algorithm in drupal_depth_first_search().

 *

 * @param $starting_updates

 *   An array whose keys contain the names of modules with updates to be run

 *   and whose values contain the number of the first requested update for that

 *   module.

 *

 * @return

 *   An array whose keys are the names of all update functions within the

 *   provided modules that would need to be run in order to fulfill the

 *   request, arranged in the order in which the update functions should be

 *   run. (This includes the provided starting update for each module and all

 *   subsequent updates that are available.) The values are themselves arrays

 *   containing all the keys provided by the drupal_depth_first_search()

 *   algorithm, which encode detailed information about the dependency chain

 *   for this update function (for example: 'paths', 'reverse_paths', 'weight',

 *   and 'component'), as well as the following additional keys:

 *   - 'allowed': A boolean which is TRUE when the update function's

 *     dependencies are met, and FALSE otherwise. Calling functions should

 *     inspect this value before running the update.

 *   - 'missing_dependencies': An array containing the names of any other

 *     update functions that are required by this one but that are unavailable

 *     to be run. This array will be empty when 'allowed' is TRUE.

 *   - 'module': The name of the module that this update function belongs to.

 *   - 'number': The number of this update function within that module.

 *

 * @see drupal_depth_first_search()

 */

function update_resolve_dependencies($starting_updates) {

  // Obtain a dependency graph for the requested update functions.

  $update_functions = update_get_update_function_list($starting_updates);

  $graph = update_build_dependency_graph($update_functions);

  // Perform the depth-first search and sort the results.

  require_once DRUPAL_ROOT . '/includes/graph.inc';

  drupal_depth_first_search($graph);

  uasort($graph, 'drupal_sort_weight');

  foreach ($graph as $function => &$data) {

    $module = $data['module'];

    $number = $data['number'];

    // If the update function is missing and has not yet been performed, mark

    // it and everything that ultimately depends on it as disallowed.

    if (update_is_missing($module, $number, $update_functions) && !update_already_performed($module, $number)) {

      $data['allowed'] = FALSE;

      foreach (array_keys($data['paths']) as $dependent) {

        $graph[$dependent]['allowed'] = FALSE;

        $graph[$dependent]['missing_dependencies'][] = $function;

      }

    }

    elseif (!isset($data['allowed'])) {

      $data['allowed'] = TRUE;

      $data['missing_dependencies'] = array();

    }

    // Now that we have finished processing this function, remove it from the

    // graph if it was not part of the original list. This ensures that we

    // never try to run any updates that were not specifically requested.

    if (!isset($update_functions[$module][$number])) {

      unset($graph[$function]);

    }

  }

  return $graph;

}

/**

 * Returns an organized list of update functions for a set of modules.

 *

 * @param $starting_updates

 *   An array whose keys contain the names of modules and whose values contain

 *   the number of the first requested update for that module.

 *

 * @return

 *   An array containing all the update functions that should be run for each

 *   module, including the provided starting update and all subsequent updates

 *   that are available. The keys of the array contain the module names, and

 *   each value is an ordered array of update functions, keyed by the update

 *   number.

 *

 * @see update_resolve_dependencies()

 */

function update_get_update_function_list($starting_updates) {

  // Go through each module and find all updates that we need (including the

  // first update that was requested and any updates that run after it).

  $update_functions = array();

  foreach ($starting_updates as $module => $version) {

    $update_functions[$module] = array();

    $updates = drupal_get_schema_versions($module);

    if ($updates !== FALSE) {

      $max_version = max($updates);

      if ($version <= $max_version) {

        foreach ($updates as $update) {

          if ($update >= $version) {

            $update_functions[$module][$update] = $module . '_update_' . $update;

          }

        }

      }

    }

  }

  return $update_functions;

}

/**

 * Constructs a graph which encodes the dependencies between module updates.

 *

 * This function returns an associative array which contains a "directed graph"

 * representation of the dependencies between a provided list of update

 * functions, as well as any outside update functions that they directly depend

 * on but that were not in the provided list. The vertices of the graph

 * represent the update functions themselves, and each edge represents a

 * requirement that the first update function needs to run before the second.

 * For example, consider this graph:

 *

 * system_update_7000 ---> system_update_7001 ---> system_update_7002

 *

 * Visually, this indicates that system_update_7000() must run before

 * system_update_7001(), which in turn must run before system_update_7002().

 *

 * The function takes into account standard dependencies within each module, as

 * shown above (i.e., the fact that each module's updates must run in numerical

 * order), but also finds any cross-module dependencies that are defined by

 * modules which implement hook_update_dependencies(), and builds them into the

 * graph as well.

 *

 * @param $update_functions

 *   An organized array of update functions, in the format returned by

 *   update_get_update_function_list().

 *

 * @return

 *   A multidimensional array representing the dependency graph, suitable for

 *   passing in to drupal_depth_first_search(), but with extra information

 *   about each update function also included. Each array key contains the name

 *   of an update function, including all update functions from the provided

 *   list as well as any outside update functions which they directly depend

 *   on. Each value is an associative array containing the following keys:

 *   - 'edges': A representation of any other update functions that immediately

 *     depend on this one. See drupal_depth_first_search() for more details on

 *     the format.

 *   - 'module': The name of the module that this update function belongs to.

 *   - 'number': The number of this update function within that module.

 *

 * @see drupal_depth_first_search()

 * @see update_resolve_dependencies()

 */

function update_build_dependency_graph($update_functions) {

  // Initialize an array that will define a directed graph representing the

  // dependencies between update functions.

  $graph = array();

  // Go through each update function and build an initial list of dependencies.

  foreach ($update_functions as $module => $functions) {

    $previous_function = NULL;

    foreach ($functions as $number => $function) {

      // Add an edge to the directed graph representing the fact that each

      // update function in a given module must run after the update that

      // numerically precedes it.

      if ($previous_function) {

        $graph[$previous_function]['edges'][$function] = TRUE;

      }

      $previous_function = $function;

      // Define the module and update number associated with this function.

      $graph[$function]['module'] = $module;

      $graph[$function]['number'] = $number;

    }

  }

  // Now add any explicit update dependencies declared by modules.

  $update_dependencies = update_retrieve_dependencies();

  foreach ($graph as $function => $data) {

    if (!empty($update_dependencies[$data['module']][$data['number']])) {

      foreach ($update_dependencies[$data['module']][$data['number']] as $module => $number) {

        $dependency = $module . '_update_' . $number;

        $graph[$dependency]['edges'][$function] = TRUE;

        $graph[$dependency]['module'] = $module;

        $graph[$dependency]['number'] = $number;

      }

    }

  }

  return $graph;

}

/**

 * Determines if a module update is missing or unavailable.

 *

 * @param $module

 *   The name of the module.

 * @param $number

 *   The number of the update within that module.

 * @param $update_functions

 *   An organized array of update functions, in the format returned by

 *   update_get_update_function_list(). This should represent all module

 *   updates that are requested to run at the time this function is called.

 *

 * @return

 *   TRUE if the provided module update is not installed or is not in the

 *   provided list of updates to run; FALSE otherwise.

 */

function update_is_missing($module, $number, $update_functions) {

  return !isset($update_functions[$module][$number]) || !function_exists($update_functions[$module][$number]);

}

/**

 * Determines if a module update has already been performed.

 *

 * @param $module

 *   The name of the module.

 * @param $number

 *   The number of the update within that module.

 *

 * @return

 *   TRUE if the database schema indicates that the update has already been

 *   performed; FALSE otherwise.

 */

function update_already_performed($module, $number) {

  return $number <= drupal_get_installed_schema_version($module);

}

/**

 * Invokes hook_update_dependencies() in all installed modules.

 *

 * This function is similar to module_invoke_all(), with the main difference

 * that it does not require that a module be enabled to invoke its hook, only

 * that it be installed. This allows the update system to properly perform

 * updates even on modules that are currently disabled.

 *

 * @return

 *   An array of return values obtained by merging the results of the

 *   hook_update_dependencies() implementations in all installed modules.

 *

 * @see module_invoke_all()

 * @see hook_update_dependencies()

 */

function update_retrieve_dependencies() {

  $return = array();

  // Get a list of installed modules, arranged so that we invoke their hooks in

  // the same order that module_invoke_all() does.

  $modules = db_query("SELECT name FROM {system} WHERE type = 'module' AND schema_version <> :schema ORDER BY weight ASC, name ASC", array(':schema' => SCHEMA_UNINSTALLED))->fetchCol();

  foreach ($modules as $module) {

    $function = $module . '_update_dependencies';

    if (function_exists($function)) {

      $result = $function();

      // Each implementation of hook_update_dependencies() returns a

      // multidimensional, associative array containing some keys that

      // represent module names (which are strings) and other keys that

      // represent update function numbers (which are integers). We cannot use

      // array_merge_recursive() to properly merge these results, since it

      // treats strings and integers differently. Therefore, we have to

      // explicitly loop through the expected array structure here and perform

      // the merge manually.

      if (isset($result) && is_array($result)) {

        foreach ($result as $module => $module_data) {

          foreach ($module_data as $update => $update_data) {

            foreach ($update_data as $module_dependency => $update_dependency) {

              // If there are redundant dependencies declared for the same

              // update function (so that it is declared to depend on more than

              // one update from a particular module), record the dependency on

              // the highest numbered update here, since that automatically

              // implies the previous ones. For example, if one module's

              // implementation of hook_update_dependencies() required this

              // ordering:

              //

              // system_update_7001 ---> user_update_7000

              //

              // but another module's implementation of the hook required this

              // one:

              //

              // system_update_7002 ---> user_update_7000

              //

              // we record the second one, since system_update_7001() is always

              // guaranteed to run before system_update_7002() anyway (within

              // an individual module, updates are always run in numerical

              // order).

              if (!isset($return[$module][$update][$module_dependency]) || $update_dependency > $return[$module][$update][$module_dependency]) {

                $return[$module][$update][$module_dependency] = $update_dependency;

              }

            }

          }

        }

      }

    }

  }

  return $return;

}