$_SERVER['DOCUMENT_ROOT'] returns path with repeated directory name

Question

I am seeing a strange behavior when accessing $_SERVER['DOCUMENT_ROOT'] on a subdomain. It contains a duplicate folder name which does not exist.

Here is the the relevant output of $_SERVER:

[DOCUMENT_ROOT] => /var/www/sub.domainname.com/sub.domainname.com
[SCRIPT_FILENAME] => /var/www/sub.domainname.com/index.php

It should be:

[DOCUMENT_ROOT] => /var/www/sub.domainname.com

Here is the virtual host configuration:

<VirtualHost *:80>
    ServerAdmin webmaster@localhost
    ServerName sub.domainname.com

    DocumentRoot /var/www/sub.domainname.com
    <Directory />
        Options FollowSymLinks
        AllowOverride All
    </Directory>
    <Directory /var/www/sub.domainname.com>
        Options Indexes FollowSymLinks MultiViews
        AllowOverride All
        Order allow,deny
        allow from all
    </Directory>    
</VirtualHost>

That's why you should define a constant like `ROOT` and rely on that one, rather than `DOCUMENT_ROOT` — Yang, Jun 09 '14 at 15:48
I don't get why this question gets downvoted. They probably do that just for fun. +1 for the question — Yang, Jun 09 '14 at 15:50
You can define that in `index.php` like `define('ROOT', dirname(__FILE__))` — Yang, Jun 09 '14 at 15:51
I don't see any reason why this variable is considered *not reliable*. Of course there are workarounds but I'm interested in the reason for the wrong path. Can you paste your virtual host configuration for the subdomain? (+1) — Daniel W., Jun 09 '14 at 15:53
@DanFromGermany How don't you see? If you can see it right here — Yang, Jun 09 '14 at 15:54
@Scorpion but why is that? I've never come to the situation where DOCUMENT_ROOT was wrong. Neither with nginx, nor with Apache or any other server I had under administration. — Daniel W., Jun 09 '14 at 15:54
@DanFromGermany i was thinking the same thing. It's fairly common to rely on variables such as this one for auto-discovery. In fact it's pretty necessary to allow us to build easily portable base code. `DOCUMENT_ROOT` is perfectly reliable as long as you have set the webserver up correctly (and if you haven't, patching in a ROOT constant is just lazy, fix the issue!) — Lee, Jun 09 '14 at 15:56
@DanFromGermany I have added the vhost config to my question. — Derek, Jun 09 '14 at 15:59
check for .htaccess files also - a wrong document root is (as indicated by the answer below) a webserver config problem. — AD7six, Jun 09 '14 at 16:01
@Lee sometimes webserver control is not ours (ie. working on a client's server), so the reliability can not always be assumed. — Derek, Jun 09 '14 at 16:04

score 2 · Answer 1 · answered Jun 09 '14 at 15:57

This issue is likely caused by a mis-configured webserver, the PHP documentation says this $_SERVER['DOCUMENT_ROOT'] contains the script directory as defined in the servers config file. Which may therefore be different to the actual script directory location.

DOCUMENT_ROOT
The document root directory under which the current script is executing, as defined in the server's configuration file.

Source: PHP Reserved Variables $_SERVER[] Manual Page

$_SERVER['DOCUMENT_ROOT'] returns path with repeated directory name

1 Answers1

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