<?php
/*
Wordpress leading whitespace fix
================================
Ever had poorly coded plugin/theme output whitespaces causing
your RSS to stop working? You can fix that using this simple
script.

Download
--------
Plaintext version: http://wejn.org/stuff/wejnswpwhitespacefix.php
VIM Syntax colored: http://wejn.org/stuff/wejnswpwhitespacefix.php.html

Requirements
------------
Works with PHP5 only, as the headers_list() function is missing
in PHP4 which makes output Content-Type detection impossible.

Installation
------------
Either use this as auto_prepend in your .htaccess:

php_value "auto_prepend_file" /path/to/wejnswpwhitespacefix.php

or include it as first thing in Wordpress' index.php file even
before that "short and sweet" line:

<?php
include("wejnswpwhitespacefix.php");
// Short and sweet
define('WP_USE_THEMES', true);
require('./wp-blog-header.php');
?>

Author: Wejn {wejn at box dot cz}
License: GPL v2.0, no latter version(s)
*/

function ___wejns_wp_whitespace_fix($input) {
    /* valid content-type? */
    $allowed = 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\\//i", $header)) {
            $allowed = true;
        }
    }

    /* do the actual work */
    if ($allowed) {
        return preg_replace("/\\A\s*/m", "", $input);
    } else {
        return $input;
    }
}

/* start output buffering using my custom callback */
ob_start("___wejns_wp_whitespace_fix");
?>