I wanted a setup where I had a 'portal' wiki that could then link to a number of sub-domain instances of dokuwiki, the twist being that a user logging into the portal would have their session carried over to the sub-domain instances intact. With the patch included applied all I have to do is add the following to local.php for each instance:
$conf['securecookie'] = 0;
Then I softlink 'PORTAL.example.com/data/meta/_htcookiesalt' to 'EXAMPLE.PORTAL.example.com/data/meta/_htcookiesalt' so the cookies are valid across farmed instances.
Any chance of including this patch (or something functionally equivalent) into dokuwiki?
Although not tested, it should be backwards compatible as if 'session.cookie_domain' is not set, it returns '' which is what was being using previously in the calls to session_set_cookie_params() and setcookie().