Search module hack (EE 1.6.9)

/** ----------------------------------------------
        /**  Limit query to a specific category
        /** ----------------------------------------------*/       
        if (isset($_POST['cat_id']) AND is_array($_POST['cat_id']))
        {        
            $temp = '';
        
            foreach ($_POST['cat_id'] as $val)
            {
                if ($val != 'all' AND $val != '')
                {
                    $temp .= " exp_categories.cat_id = '".$DB->escape_str($val)."' OR";
                }
            } 
            
            if ($temp != '')
            {
                $temp = substr($temp, 0, -2);
            
                $sql .= ' AND ('.$temp.') ';
            }
        }

/** ----------------------------------------------
        /**  Categories
        /** ----------------------------------------------*/
        if (isset($_POST['cat_id']) AND is_array($_POST['cat_id']))
        {     
            if ($_POST['cat_id'][0] != 'all' && $_POST['cat_id'][0] != '')
            {
                // Find entries that belong to ALL selected categories
                $cat_sql = "SELECT
                            DISTINCT(exp_weblog_titles.entry_id)
                            FROM exp_weblog_titles
                            LEFT JOIN exp_weblogs ON exp_weblog_titles.weblog_id = exp_weblogs.weblog_id 
                            LEFT JOIN exp_category_posts ON exp_weblog_titles.entry_id = exp_category_posts.entry_id
                            WHERE exp_weblogs.site_id = '".$DB->escape_str($PREFS->ini('site_id'))."'";
            
                // make safe            
                foreach($_POST['cat_id'] as &$val)
                {
                    $DB->escape_str($val);
                }
                $selected_categories = "'".implode("','", $_POST['cat_id'])."'";    
                $cat_sql .= "AND exp_category_posts.cat_id IN ({$selected_categories}) 
                         GROUP BY exp_category_posts.entry_id 
                         HAVING (COUNT(exp_category_posts.entry_id) = ".count($_POST['cat_id']).") ";
                    
                $query = $DB->query($cat_sql);
            
                if ($query->num_rows == 0)
                {
                    return FALSE;
                }
                else
                {
                    // add where condition to main query
                    $sql .= "AND exp_weblog_titles.entry_id IN(";
                
                    foreach ($query->result as $row)
                    {
                        $sql .= "'".$DB->escape_str($row['entry_id'])."', ";
                    } 
                
                    $sql = substr($sql, 0, -2).")";    
                }
            }
        }