update.inc

<?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>';
    }
    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.';
        $pdo_link = 'http://drupal.org/requirements/pdo#pecl';
    }
    elseif (isset($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;
        } 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;
}