The edit page CGI defines a base tag with an URL which is not
absolute, which can break the preview function in some circumstances
(with e.g. images not showing). The trivial patch that fixes
it can be found here as well as on my
git.
That patch does mean that if you're accessing the CGI via HTTPS but your $config{url} and $config{cgiurl} are HTTP, you'll get preview images loaded via HTTP, causing the browser to complain. See want to avoid ikiwiki using http or https in urls to allow serving both for background.
Perhaps the CGI could form its
<base>URL by usingURI->new_abs(urlto(...), $cgi->url)instead?You'd also need to change
IkiWiki/Wrapper.pmto pass at least the SERVER_NAME and SERVER_PORT through the environment, probably.Joey's last comment on want to avoid ikiwiki using http or https in urls to allow serving both suggests that this might already work, but I'm not quite sure how - I'd expect it to need more environment variables? --smcv
CGI::urlusesREQUEST_URI. So it could be used, but I don't see how to get from theCGI::urlto an url to the page that is being edited. --Joey(The right rune seems to be:
URI->new_abs(urlto($params{page}), $cgi->url))--Joey
Update: This bug is worse than it first appeared, and does not only affect
previewing. The cgi always has a <base> url, and it's always relative,
and that can break various links etc. For example, when the 404 plugin
displays a missing page, it has a Recentchanges link, which would be broken
if the cgi was in an unusual place.
misctemplate needs to always set an absolute baseurl. Which is a problem,
since misctemplate is not currently passed a cgi object from which to
construct one. --Joey
Update: Worse and worse. baseurl(undef) can be a relative url, but
nearly every use of it I can find actually needs to be absolute.
the numerous redirect($q, baseurl(undef)) all need to be absolute
according to CGI documentation.
So, I'm seriously thinking about reverting the part of
want to avoid ikiwiki using http or https in urls to allow serving both
that made baseurl(undef) relative.
And I suppose, re-opening that todo. 
--Joey