Storefront top bar welcome message

functions.php

<?php
/**
 * Adds a top bar to Storefront, before the header.
 */
function storefront_add_topbar() {
    global $current_user;
    get_currentuserinfo();

    if ( ! empty( $current_user->user_firstname ) ) {
        $user = $current_user->user_firstname;
    } else {
        $user = __( 'guest', 'storefront-child' );
    }

    ?>
    <div id="topbar">
        <div class="col-full">
            <p>Welcome <?php echo $user ?>!</p>
        </div>
    </div>
    <?php
}
add_action( 'storefront_before_header', 'storefront_add_topbar' );