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Source code

function update_core($from, $to) {

	global $wp_filesystem, $_old_files, $_new_bundled_files, $wpdb;



	@set_time_limit( 300 );



	$php_version    = phpversion();

	$mysql_version  = $wpdb->db_version();

	$required_php_version = '5.2.4';

	$required_mysql_version = '5.0';

	$wp_version = '3.2';

	$php_compat     = version_compare( $php_version, $required_php_version, '>=' );

	$mysql_compat   = version_compare( $mysql_version, $required_mysql_version, '>=' ) || file_exists( WP_CONTENT_DIR . '/db.php' );



	if ( !$mysql_compat || !$php_compat )

		$wp_filesystem->delete($from, true);



	if ( !$mysql_compat && !$php_compat )

		return new WP_Error( 'php_mysql_not_compatible', sprintf( __('The update cannot be installed because WordPress %1$s requires PHP version %2$s or higher and MySQL version %3$s or higher. You are running PHP version %4$s and MySQL version %5$s.'), $wp_version, $required_php_version, $required_mysql_version, $php_version, $mysql_version ) );

	elseif ( !$php_compat )

		return new WP_Error( 'php_not_compatible', sprintf( __('The update cannot be installed because WordPress %1$s requires PHP version %2$s or higher. You are running version %3$s.'), $wp_version, $required_php_version, $php_version ) );

	elseif ( !$mysql_compat )

		return new WP_Error( 'mysql_not_compatible', sprintf( __('The update cannot be installed because WordPress %1$s requires MySQL version %2$s or higher. You are running version %3$s.'), $wp_version, $required_mysql_version, $mysql_version ) );



	// Sanity check the unzipped distribution

	apply_filters('update_feedback', __('Verifying the unpacked files…'));

	$distro = '';

	$roots = array( '/wordpress/', '/wordpress-mu/' );

	foreach( $roots as $root ) {

		if ( $wp_filesystem->exists($from . $root . 'readme.html') && $wp_filesystem->exists($from . $root . 'wp-includes/version.php') ) {

			$distro = $root;

			break;

		}

	}

	if ( !$distro ) {

		$wp_filesystem->delete($from, true);

		return new WP_Error('insane_distro', __('The update could not be unpacked') );

	}



	apply_filters('update_feedback', __('Installing the latest version…'));



	// Create maintenance file to signal that we are upgrading

	$maintenance_string = '<?php $upgrading = ' . time() . '; ?>';

	$maintenance_file = $to . '.maintenance';

	$wp_filesystem->delete($maintenance_file);

	$wp_filesystem->put_contents($maintenance_file, $maintenance_string, FS_CHMOD_FILE);



	// Copy new versions of WP files into place.

	$result = _copy_dir($from . $distro, $to, array('wp-content') );



	// Custom Content Directory needs updating now.

	// Copy Languages

	if ( !is_wp_error($result) && $wp_filesystem->is_dir($from . $distro . 'wp-content/languages') ) {

		if ( WP_LANG_DIR != ABSPATH . WPINC . '/languages' || @is_dir(WP_LANG_DIR) )

			$lang_dir = WP_LANG_DIR;

		else

			$lang_dir = WP_CONTENT_DIR . '/languages';



		if ( !@is_dir($lang_dir) && 0 === strpos($lang_dir, ABSPATH) ) { // Check the language directory exists first

			$wp_filesystem->mkdir($to . str_replace($lang_dir, ABSPATH, ''), FS_CHMOD_DIR); // If it's within the ABSPATH we can handle it here, otherwise they're out of luck.

			clearstatcache(); // for FTP, Need to clear the stat cache

		}



		if ( @is_dir($lang_dir) ) {

			$wp_lang_dir = $wp_filesystem->find_folder($lang_dir);

			if ( $wp_lang_dir )

				$result = copy_dir($from . $distro . 'wp-content/languages/', $wp_lang_dir);

		}

	}



	// Copy New bundled plugins & themes

	// This gives us the ability to install new plugins & themes bundled with future versions of WordPress whilst avoiding the re-install upon upgrade issue.

	if ( !is_wp_error($result) && ( ! defined('CORE_UPGRADE_SKIP_NEW_BUNDLED') || ! CORE_UPGRADE_SKIP_NEW_BUNDLED ) ) {

		$old_version = $GLOBALS['wp_version']; // $wp_version in local scope == new version

		foreach ( (array) $_new_bundled_files as $file => $introduced_version ) {

			// If $introduced version is greater than what the site was previously running

			if ( version_compare($introduced_version, $old_version, '>') ) {

				$directory = ('/' == $file[ strlen($file)-1 ]);

				list($type, $filename) = explode('/', $file, 2);



				if ( 'plugins' == $type )

					$dest = $wp_filesystem->wp_plugins_dir();

				elseif ( 'themes' == $type )

					$dest = trailingslashit($wp_filesystem->wp_themes_dir()); // Back-compat, ::wp_themes_dir() did not return trailingslash'd pre-3.2

				else

					continue;



				if ( ! $directory ) {

					if ( $wp_filesystem->exists($dest . $filename) )

						continue;



					if ( ! $wp_filesystem->copy($from . $distro . 'wp-content/' . $file, $dest . $filename, FS_CHMOD_FILE) )

						$result = new WP_Error('copy_failed', __('Could not copy file.'), $dest . $filename);

				} else {

					if ( $wp_filesystem->is_dir($dest . $filename) )

						continue;



					$wp_filesystem->mkdir($dest . $filename, FS_CHMOD_DIR);

					$_result = copy_dir( $from . $distro . 'wp-content/' . $file, $dest . $filename);

					if ( is_wp_error($_result) ) //If a error occurs partway through this final step, keep the error flowing through, but keep process going.

						$result = $_result;

				}

			}

		} //end foreach

	}



	// Handle $result error from the above blocks

	if ( is_wp_error($result) ) {

		$wp_filesystem->delete($maintenance_file);

		$wp_filesystem->delete($from, true);

		return $result;

	}



	// Remove old files

	foreach ( $_old_files as $old_file ) {

		$old_file = $to . $old_file;

		if ( !$wp_filesystem->exists($old_file) )

			continue;

		$wp_filesystem->delete($old_file, true);

	}



	// Upgrade DB with separate request

	apply_filters('update_feedback', __('Upgrading database…'));

	$db_upgrade_url = admin_url('upgrade.php?step=upgrade_db');

	wp_remote_post($db_upgrade_url, array('timeout' => 60));



	// Remove working directory

	$wp_filesystem->delete($from, true);



	// Force refresh of update information

	if ( function_exists('delete_site_transient') )

		delete_site_transient('update_core');

	else

		delete_option('update_core');



	// Remove maintenance file, we're done.

	$wp_filesystem->delete($maintenance_file);

}