Attachments: The "edit in office" link or "Edit document" button should not be shown if the user has no permission to add or remove attachments in this space

Have space where a given user can view the pages of space and add them.
However he has no permission for attachments either as an individual user or as a confluence-user. I have explicitly removed the permissions.

have another user with attachment permissions adding a word attachment to a page. Test that editing in office is OK and that you can modify the document attachment.

Switch back to the first user and go to the same page.
There is a the link on the left to open the document in R/O, fine.
There is also a link at right to edit in office the same document.
Use it.

Now try to save, an error reported in word when he saves (see attachment with error popup from word), this is MISLEADING to show this edit in office link in the first place. Do not show it if the user has the add permission for the attachments otherwise it is doomed to fail.
The stack trace of the error on the server is in a comment below. The server does its job properly but the link should not be shown in the first place.

If you use the view link to Htmlized the office document, you also have an EDIT button which should be removed.

2011/01/12 update
I raise it from minor to major.
My testers complain, and they are totally right, that the system lets them do something which fails at the end (saving from Word).
It should not happen in the first place so show the link or the button.
I think that it is really a 30 minutes job to fix the two screens based on the permissions.