Any way to make it so an edit page doesn't offer the attachment capability
unless it matches a specific user, is an admin, and/or is an allowed page?
(For now, I have it on all pages, and then it prohibits after I submit
based on the allowed_attachments.)

> To do that, ikiwiki would have to try to match the `allowed_attachments`
> pagespec against a sort of dummy upload to the current page. Then if it
> failed, assume all real uploads would fail. Now consider a pagespec like
> "user(joey) and mimetype(audio/mpeg)" -- it'd be hard to make a dummy
> upload to test this pagespec against.
> 
> So, there would need to be some sort of test mode, where terms like
> `mimetype()` always succeed. But then consider a pagespec like
> "user(joey) and !mimetype(video/mpeg)" -- if mimetype succeeds, this
> fails.
> 
> So, maybe we can instead just filter out all the pagespec terms aside
> from `user()`, `ip()`, and `admin()`. Transforming that into just
> "user(joey)", which would succeed in the test.
> 
> That'd work, I guess. Pulling a pagespec apart, filtering out terms, and
> putting it back together is nontrivial, but doable.
> 
> Other approach would be to have a separate pagespec that explicitly
> controlls what pages to show the attachment UI on. --[[Joey]] 
