$_SERVER['document_root'] returns /htdocs not /public_html

Question

I'm looking to switch over to a new host, and they provide this nice little "temporary url" to test out your files before you switch. All fine and dandy. So I copy over all of my files. At the top of every page I require another file from the server that is stored at public_html/includes/head.php. Now for whatever reason, the $_SERVER['document_root'] var is returning /public_html/htdocs/includes/head.php (which does not exist on the server) and not /public_html/includes/head.php (which does exist). The resulting error is as follows:

Warning: require_once(/home/secure31/public_html/htdocs/includes/head.php) 
[function.require-once]: failed to open stream: Permission denied in 
/home/stephe80/public_html/index.php on line 6

The guilty code:

require_once($_SERVER['DOCUMENT_ROOT'] . '/includes/head.php');

I am inclined to think that this is an error associated with their temporary url setup, but I do not want to transfer over my DNS and find that all of my files are broken. I could change them to absolute paths, but I am curious as to whether I am missing something. Any insight would be appreciated. Thanks!

Answer 1

I'd suggest to use the __FILE__ constant and work out your htdocs folder from there. It's much more reliable than relying on the $_SERVER superglobal, since that actually differs from server to server.

Example (that you'd call in your index.php in root folder):

$htdocs = str_replace(basename(__FILE__), __FILE__, '');
define('ROOT_FOLDER', $htdocs);
require_once(ROOT_FOLDER . '/includes/head.php');

Answer 2

For future reference (if anyone has similar issues), it turns out that the problem was with their test server. I launched it with my code as-was (risky, I know), and all turned out well.