Whitespace fix for php

whitespace-fix.php

<?php
/**
 * this is a fix mainly for wordpress, to prevent xml error
 * 
 * this solution is from http://www.vichaunter.com/desarrollo-web/solucion-para-error-line-2-column-6-xml-declaration-allowed-start-document-wordpress
 *
 */

function ___wejns_wp_whitespace_fix($input) {
    /* valid content-type? */
    $allowed = false;

    /* found content-type header? */
    $found = false;
    /* we mangle the output if (and only if) output type is text/* */
    foreach (headers_list() as $header) {
        if (preg_match("/^content-type:\\s+(text\\/|application\\/((xhtml|atom|rss)\\+xml|xml))/i", $header)) {
            $allowed = true;
        }

        if (preg_match("/^content-type:\\s+/i", $header)) {
            $found = true;
        }
    }

    /* do the actual work */
    if ($allowed || !$found) {
        return preg_replace("/\\A\\s*/m", "", $input);
    } else {
        return $input;
    }
}
 
/* start output buffering using custom callback */
ob_start("___wejns_wp_whitespace_fix");