MIME database

[ludo@gnu.org (Ludovic Courtès)]

Hello,

(Moving the discussions to guix-devel.)

brendan.tildesley@openmailbox.org skribis:

> I was wondering why my pdf documents were getting opened in Gimp by default instead of Evince, so I investigated xdg-open and found it uses mimeopen as a fallback, and packaged it. Turns out it didn't make a difference and the issue was simply that the generated mimedata.cache in xdg-mime-database had Gimp listed before Evince.

Oh, good catch.  Profile generation is sensitive to package order; so
indeed, if GIMP comes first, it “wins.”

> I was also I little confused that xdg-mime-database produces so many conflicts with shared-mime-info. It's role appears to be to update the data in shared-mime-data and have it overshadow the original data when  conflicts are resolved during profile generation. Looks ugly seeing all those conflicts though.

I guess it’s OK in that users normally don’t want to install these
packages at all, let alone installing both in the same profile.

> I had a look at Fedora's version. They just have a single shared-mime-data package that runs update-mime-database, but also they add a few changes to make Evince open pdf's instead of Gimp, among other changes.
>
> This makes me feel that it's desirable for us to also tweak mimedata to make it more sensible -- Pdf's should open in a pdf reader before it opens in an image editor. It seems unrealistic to only tweak upstream projects to make all this mimedata mesh together perfectly to produce ideal default behaviour.

Right, so I think the immediate course of action here would be to patch
GIMP’s MIME data so that it does not register as a PDF viewer.

If we stumble upon other issues like that, we can fix them similarly.

How does that sound?

Thanks for investigating!

Ludo’.