Desktop standards, MIME info cache, and Lintian

[Russ Allbery <rra@debian.org>]

Hello all,

I started looking today in more depth at the MIME type registration
process for applications providing *.desktop files, dh_desktop, and what
Lintian is currently doing (as part of addressing #488832).

Current situation: Lintian warns of packages that contain desktop files in
the debian/* directory of the source package and depend on debhelper but
don't call dh_desktop in debian/rules.  Packages that don't use debhelper
don't receive any checks.

What I've implemented: In resolving #488832, I plan on removing that check
and instead checking whether packages that ship *.desktop files containing
MimeType keys call update-desktop-database in their postinst.  This is a
more direct check that verifies the actions of dh_desktop and will also
catch packages that don't use debhelper or that don't have a conventional
debian/rules file (such as CDBS packages).

I think that's an improvement.  However, in investigating further, I'd
like some advice.  My questions:

1. The update-desktop-database program used to be documented in the
   desktop entry spec in version 0.9.5 and was removed in 0.9.6 (the
   current version is 1.0).  Should I draw some conclusion from that?  Is
   this program and cache likely to go away?  Is it still really used?
   (It also seems odd that a cache regenerated from installed files is
   written to /usr/share rather than in /var.)

2. Should Lintian be continuing to recommend that people installing
   *.desktop files call dh_desktop just in case, even if there are no
   MimeType entries in the *.desktop files?  I've been leaning that way in
   the past, but given how long it's been since dh_desktop was added and
   given that it still doesn't do anything else, I wonder if this isn't
   just noise.  I'm currently leaning towards removing the check for
   dh_desktop in favor of only checking for update-desktop-database when
   there are *.desktop files with MimeInfo unless someone tells me that's
   a bad idea.

3. Does the Shared MIME-info Database or the update-mime-info program have
   anything to do with this?  I think I've convinced myself that they
   don't, but I'd love confirmation from someone who works more intensely
   in the desktop environment world than I.

Thanks in advance!

-- 
Russ Allbery (rra@debian.org)               <http://www.eyrie.org/~eagle/>