[fprint] Planning libfprint API changes (2.x)

Mon Aug 12 12:58:44 UTC 2019

Hi,

I am wrapping up the libfprint update, and I am also adding automated
tests using umockdev. In the future, it will be mandatory for drivers
to ship a simple umockdev based test case.

This is something where I would really appreciate help. If anyone has a
device, please have a look at the test/README-umockdev and submit a new
test for it.

Please note, that umockdev currently has a bug, this may cause random
test failures. So if the created test fails sometimes, this is to be
expected:
  https://github.com/martinpitt/umockdev/pull/92

At this point all drivers are ported. A lot of them have not been
tested though, so any help here is still appreciated (also, see above
for submitting automated tests).

Known to be working:
 * vfs101
 * upektc_img
 * aes2660 and aes1660
 * aes2550
 * synaptics (new)

Known to have issues:
 * etes603

I should have an elan device soon, but if anyone can test it, that
would be useful.

Benjamin

On Wed, 2019-07-10 at 14:09 +0200, Benjamin Berg wrote:
> so, I have worked on this for a while now, and I pushed my changes to
> the
>   https://gitlab.freedesktop.org/libfprint/libfprint/commits/wip/benzea/v2
> branch.
> 
> This is not yet quite complete. Some changes are more invasive,
> others
> are less so. Most drivers have been ported at this point (fixing a
> number of issues in the process). Unfortunately, I have only been
> able
> to test two of the drivers on real hardware.
> 
> It would be great if people could take a look and test this. For
> testing, you have two ways:
>  * Grab the git repository and build locally
>    - Run demo/gtk-libfprint-test as root from the build directory
>  * Grab the flatpak from the CI pipeline, then:
>    - Add e.g. the flathub repository (by going to flathub.org)
>    - flatpak install org.gnome.Platform/x86_64/3.32
>    - flatpak install --no-deps --bundle DOWNLOADED_FLATPAK
>    - Make sure your user can access the USB device in /dev/bus/usb
>    - flatpak run org.freedesktop.libfprint.Demo
> 
> When testing, please watch out for warnings that may need to be
> fixed.
> 
> I am planning in adding a way to record a trace of the USB traffic.
> The
> idea is that we can run a basic simulation as a CI test. But I am not
> sure how this will look like in the end.
> 
> Some of the highlights:
>  * Working CI using a new virtual image driver
>  * Generation of GIR data (i.e. various language bindings)
>  * More convenient USB API for drivers
> 
> From the user perspective, the API changes in the following ways:
>  * Use of GLib style asynchronous API with cancellation handling
>  * A new FpContext object, that handles enumeration and hotplugging
>  * FpPrint (was struct fp_print) can now stores some more metadata:
>    - Username
>    - Description
>    - Enroll Date
>  * The enroll call now takes a template print, this is so that the
>    driver could make use of the above metadata.
>  * Retry conditions are just errors, but they are in the
>    FP_DEVICE_RETRY error domain.
>  * New "list" and "delete" commands (not quite there but this is
> purely
>    something for the drivers to handle).
>  * Requires GLib mainloop
> 
> On the drivers side, the API has not changed as much. There are a
> number of changes in the boilerplate code though and changed function
> names. Other than that:
>  * Updated custom USB transfer API (no libusb anymore)
>    - Starting a transfer always succeeds (simplified error handling)
>    - More convenient parameters for the callback function
>  * Changed error reporting (GError instead of pure integer)
> 
> Comments and feedback are welcome!
> 
> Benjamin
> 
> On Tue, 2019-06-18 at 10:48 +0200, Benjamin Berg wrote:
> > I realised that I only had talked to a few individuals about this,
> > so
> > it seems like a good idea to inform the ML about some of the ideas.
> > 
> > The current situation is that we are looking at adding support for
> > devices that store the print data in the sensor. With these
> > devices,
> > a
> > few new operations will be necessary:
> > 
> >  * Deleting prints from the device when deleting them from the host
> >    
> > https://gitlab.freedesktop.org/libfprint/libfprint/merge_requests/54
> >  * Garbage collecting old prints
> >    (e.g. left over from e.g. old installations)
> >    - Listing prints from the device
> >    - Deleting prints that are unknown on the host
> > 
> > Another important change is to support non-USB devices. My main
> > motivation for this right now is adding virtual devices for testing
> >   
> > https://gitlab.freedesktop.org/libfprint/libfprint/merge_requests/53
> > 
> > 
> > After some discussions, the idea is to bump the soname/version of
> > libfprint and then add the required API for the mentioned sensors.
> > Doing so also gives us the chance to clean up the external API.
> > 
> > I am currently looking into this, considering the following:
> >  * A GLib based external (and internal API)
> >    - Allows proper async operations and cancellation
> >    - Use GError for error reporting; so that applications don't
> >      need to assume libusb error codes
> >    - Removes the need for custom mainloop code
> >  * Possibly port libfprint to libgusb rather than libusb
> >    - Hopefully easier integration with the above changes
> >  * Dropping the special fp_dscv_dev and just having an fp_dev
> >    that needs to be opened/closed.
> >  * Handling fp_imgdev as a "subclass" (i.e. with the fp_dev struct
> >    embedded at the start). Maybe even as a GObject.
> > 
> > This will to result in a lot of collateral changes in all drivers.
> > 
> > Benjamin
> > _______________________________________________
> > fprint mailing list
> > fprint at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/fprint
> 
> _______________________________________________
> fprint mailing list
> fprint at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/fprint

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