[Mediawiki-l] Ampersand strips rest of page title in MW 1.4 installation

Brion Vibber brion at pobox.com
Thu Jun 30 19:23:35 UTC 2005

Tim Pritlove wrote:
> On 29.06.2005, at 19:35, Brion Vibber wrote:
>> Tim Pritlove wrote:
>>> Pages that contain an Ampersand no longer show up. Whenever I  click  on
>>> a link to that page, it strips the page title beginning from the
>>> Ampersand resulting in an unknown page name.
>> Are you using Apache rewrite rules? Are they different? What are they,
>> exactly?
> i use rewriting. The rules are:
>         <IfModule mod_rewrite.c>
>                 RewriteEngine On
>                 RewriteCond %{REQUEST_METHOD} ^TRACE
>                 RewriteRule .* - [F]
>                 RewriteRule ^/wiki/?(.*)$ /mediawiki/index.php?title= $1
> [L]
>         </IfModule>

Apache's mod_rewrite un-escapes various hex-encoded characters which
have special meaning in URLs, most insidiously the question mark (?) and
ampersand (&).

The result of this is that an incoming URL like:


gets rewritten to:


whose query string gets parsed into this list:

  title => 'AT'
  T     => ''

There's an easy workaround, and a more complete fix. The easy workaround
is (at least if you're using PHP as an Apache module) to switch to using
the PATH_INFO-style URLs:

   RewriteRule ^/wiki/?(.*)$ /mediawiki/index.php/$1 [QSA,L]

The '&' character has no special meaning in the _path_ part of the URL
so the rewritten form works:


However now you'll find that titles with question marks fail similarly,
because the question mark separates the path from the query string:


On our own servers we use a patched version of Apache which adds a
rewrite processing function to specifically re-escape the ampersand into
%26. You'll find a patch for Apache 1.3.x in the MediaWiki distribution
as maintenance/apache-ampersand.diff

Use is something like:

     RewriteMap ampescape int:ampescape
     RewriteRule ^/wiki/(.*)$ /w/index.php?title=${ampescape:$1} [QSA,L]

Alternatively, you might try replacing the rewrite rule with an alias to

   Alias /wiki /var/www/mediawiki/index.php

or other such tricks to use the built-in PATH_INFO usage.

-- brion vibber (brion @ pobox.com)
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