[Fingerforce-devel] Bug#683863: libfprint0: udev rules not applied when libfprint0 is installed

[Didier Raboud]

tags 683863 +moreinfo
thanks

Le samedi, 4 août 2012 23.56:02, Andrew Pimlott a écrit :
> Package: libfprint0
> Version: 1:0.4.0-4-gdfff16f-4
> Severity: normal
> 
> Dear Maintainer,

Hi Andrew, and thanks for your bugreport,

> libfprint0 installs some udev rules to make fingerprint readers
> accessible to the plugdev group.  However, since many fingerprint
> readers are built-in to computers, they are never plugged in, and thus
> the udev rules never fire. 

In my experience, that's partially wrong: the udev rules get run (at least) at 
boot time. Are you really experiencing this problem for a device or is it a 
theoretical problem?

>                            The result is that after installing the
> package, the fingerprint reader does not work for non-root users.

If the udev rules don't get run, OK.

> libfprint0 should trigger the udev rules when it installs them. 

I don't think that libfprint should be special-cased here. On my system, there 
are 32 different packages installing udev rules under /lib/udev/rules.d and 
libfprint is certainly not the only one that would benefit from "udevadm 
trigger" runs.

In my understanding of the situation of the udev rules, there is a requirement 
to reboot to have things working correctly; and that's nothing libfprint 
should fix for its own benefit.

>                                                                  I think
> this can be done with the "udevadm trigger" command.  By default, this
> will trigger change events for all devices.  I'm not sure whether that
> could have undesirable consequences.  You could limit the events to just
> fingerprint readers with a series of
> 
>     udevadm trigger --attr-match=idVendor=xxxx --attr-match=idProduct=xxxx
> 
> Possible dh_installudev should help you with this.

As mentionned above, I don't think it's libfprint's job to handle this: if 
deemed useful, it should be done by dh_installudev (that doesn't do much else 
than installing the udev rules file) or by a udev dpkg trigger.

I'm CC'ing the udev maintainer to have his input on this. Marco: opinions?

Cheers,

OdyX
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