A HitchHackers guide through WordPress

Source code

function is_blog_installed() {

	global $wpdb;



	// Check cache first. If options table goes away and we have true cached, oh well.

	if ( wp_cache_get( 'is_blog_installed' ) )

		return true;



	$suppress = $wpdb->suppress_errors();

	if ( ! defined( 'WP_INSTALLING' ) ) {

		$alloptions = wp_load_alloptions();

	}

	// If siteurl is not set to autoload, check it specifically

	if ( !isset( $alloptions['siteurl'] ) )

		$installed = $wpdb->get_var( "SELECT option_value FROM $wpdb->options WHERE option_name = 'siteurl'" );

	else

		$installed = $alloptions['siteurl'];

	$wpdb->suppress_errors( $suppress );



	$installed = !empty( $installed );

	wp_cache_set( 'is_blog_installed', $installed );



	if ( $installed )

		return true;



	// If visiting repair.php, return true and let it take over.

	if ( defined( 'WP_REPAIRING' ) )

		return true;



	$suppress = $wpdb->suppress_errors();



	// Loop over the WP tables.  If none exist, then scratch install is allowed.

	// If one or more exist, suggest table repair since we got here because the options

	// table could not be accessed.

	$wp_tables = $wpdb->tables();

	foreach ( $wp_tables as $table ) {

		// The existence of custom user tables shouldn't suggest an insane state or prevent a clean install.

		if ( defined( 'CUSTOM_USER_TABLE' ) && CUSTOM_USER_TABLE == $table )

			continue;

		if ( defined( 'CUSTOM_USER_META_TABLE' ) && CUSTOM_USER_META_TABLE == $table )

			continue;



		if ( ! $wpdb->get_results( "DESCRIBE $table;" ) )

			continue;



		// One or more tables exist. We are insane.



		// Die with a DB error.

		$wpdb->error = sprintf( /*WP_I18N_NO_TABLES*/'One or more database tables are unavailable.  The database may need to be <a href="%s">repaired</a>.'/*/WP_I18N_NO_TABLES*/, 'maint/repair.php?referrer=is_blog_installed' );

		dead_db();

	}



	$wpdb->suppress_errors( $suppress );



	wp_cache_set( 'is_blog_installed', false );



	return false;

}