+if ( is_blog_installed() ) {
+ display_header();
+ die( '<h1>' . __( 'Already Installed' ) . '</h1><p>' . __( 'You appear to have already installed WordPress. To reinstall please clear your old database tables first.' ) . '</p><p class="step"><a href="' . esc_url( wp_login_url() ) . '" class="button button-large">' . __( 'Log In' ) . '</a></p></body></html>' );
+}
+
+/**
+ * @global string $wp_version
+ * @global string $required_php_version
+ * @global string $required_mysql_version
+ * @global wpdb $wpdb
+ */
+global $wp_version, $required_php_version, $required_mysql_version;
+
+$php_version = phpversion();
+$mysql_version = $wpdb->db_version();
+$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 )
+ $compat = sprintf( __( 'You cannot install because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires PHP version %2$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 )
+ $compat = sprintf( __( 'You cannot install because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires PHP version %2$s or higher. You are running version %3$s.' ), $wp_version, $required_php_version, $php_version );
+elseif ( !$mysql_compat )
+ $compat = sprintf( __( 'You cannot install because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires MySQL version %2$s or higher. You are running version %3$s.' ), $wp_version, $required_mysql_version, $mysql_version );
+
+if ( !$mysql_compat || !$php_compat ) {
+ display_header();
+ die( '<h1>' . __( 'Insufficient Requirements' ) . '</h1><p>' . $compat . '</p></body></html>' );
+}
+
+if ( ! is_string( $wpdb->base_prefix ) || '' === $wpdb->base_prefix ) {
+ display_header();
+ die( '<h1>' . __( 'Configuration Error' ) . '</h1><p>' . __( 'Your <code>wp-config.php</code> file has an empty database table prefix, which is not supported.' ) . '</p></body></html>' );
+}
+
+// Set error message if DO_NOT_UPGRADE_GLOBAL_TABLES isn't set as it will break install.
+if ( defined( 'DO_NOT_UPGRADE_GLOBAL_TABLES' ) ) {
+ display_header();
+ die( '<h1>' . __( 'Configuration Error' ) . '</h1><p>' . __( 'The constant DO_NOT_UPGRADE_GLOBAL_TABLES cannot be defined when installing WordPress.' ) . '</p></body></html>' );
+}
+
+/**
+ * @global string $wp_local_package
+ * @global WP_Locale $wp_locale
+ */
+$language = '';
+if ( ! empty( $_REQUEST['language'] ) ) {
+ $language = preg_replace( '/[^a-zA-Z_]/', '', $_REQUEST['language'] );
+} elseif ( isset( $GLOBALS['wp_local_package'] ) ) {
+ $language = $GLOBALS['wp_local_package'];
+}