Flatpaking of Paperwork: Issues with locale-specific files and scanner drivers

[Bastien Nocera]

On Fri, 2017-10-13 at 12:03 +0200, Alexander Larsson wrote:
> On Thu, 2017-10-12 at 14:09 +0200, Bastien Nocera wrote:
> > On Thu, 2017-10-12 at 13:45 +0200, Alexander Larsson wrote:
> > > 
> > 
> > <snip>1
> > > > - Paperwork uses Sane to access scanners. However, Sane only
> > > > has
> > > > user-land drivers (most uses libusb I guess). Most users don't
> > > > have
> > > > saned (Sane daemon) enabled on their system. Therefore, libsane
> > > > usually access directly the scanner(s) using the user-land
> > > > drivers
> > > > bundled with it. I can easily package all the open-source
> > > > drivers
> > > > of
> > > > sane-backends with Paperwork, but some people have scanners
> > > > requiring
> > > > proprietary drivers. For instance, my Brother scanner is
> > > > installed
> > > > using a shell script provided by Brother, and this shell script
> > > > download and install .deb files.
> > > 
> > > You can make an app extension point for this, then people can
> > > package
> > > drivers either as flatpaks, or by using "unmanaged extensions"
> > > which
> > > are just a correctly named directory on the host acting as an
> > > extension.
> > 
> > We still need to think of a way to handle "generic" USB devices. I
> > think that using saned in the same way we use PulseAudio, Pipewire
> > and
> > co. (authorisation agent) would probably be the best way to solve
> > the
> > problem for Flatpak.
> > 
> > It's quite a bit of work, but that's pretty much the only way to
> > get
> > hotplug support, remote device discovery, all handled in a way
> > that'd
> > integrate well with Flatpak.
> > 
> > I don't think that each scanning application having its own SANE
> > stack
> > is a good way to solve that problem.
> 
> I think this is true, but it also makes packaging such apps much
> harder, as you suddenly need to convince distros to change how sane
> is
> packaged, no?

I'm not sure it's that different to expecting other sandbox-aware
daemons to be installed in the distribution.

You also would not be able to use any hotplug support. So you can't
launch your scanner app and then plug it in, because of the way the
devices are set up in the sandbox.

Ideally, saned is pretty much exactly what the doctor ordered, and
already supports everything using the sane libraries directly supports
(enumeration, accessing all the features of the scanner), has a stable
ABI/protocol and maybe supports authorisation in a modular way that can
be integrated in gnome-shell.

And though saned wouldn't live in the sandbox, we can still lock it
down quite a fair bit with systemd's lockdown features.

Do any of the SANE/saned developers care to comment?

Cheers