Limit WordPress search to currently logged in user

limit_search.php

<?php

function limit_search_author( $query ) {
    
    if ( $query->is_search ) {
    
        $current_user = wp_get_current_user();
        
        if ( !( $current_user instanceof WP_User ) )
            return $query;
        
        if ( 0 != $current_user->ID ) {        
            $query->set( 'author', $current_user->ID );
        }
            
    }
    
    return $query;
    
}

add_filter( 'pre_get_posts', 'limit_search_author' );

?>