[sane-devel] XSANE ... hotplug & 'mail image' probs.

Klaus-Peter Schrage kpschrage@gmx.de
Tue, 21 Sep 2004 17:46:40 +0200

Bertrik Sikken wrote:
> Adam Bogacki wrote:
>> Having got XSANE working, I have two problems.
>> (1) I installed hotplug with permissions to allow user access after 
>> hotplugging.
>> That works. However a problem arises when using Applications -> 
>> Graphics -> XSane as user,
>> XSane tells me 'no devices available', but on pulling out and 
>> re-inserting the scanner
>> plug it works. How does one alter permissions to allow the above to 
>> work without
>> disabling hotplug ?
> In the 2.6.x range of kernels there is a weird issue (=bug?), i.e.
> there is a race between the hotplug event and the creation of the
> libusb 'device file' (in /proc/bus/usb).
> The libusbscanner hotplug script does not take this into account
> so it may happen sometimes that the script tries to update permission
> for a file that doesn't exist yet.

Just a guess, but Adam's problem might be caused by another race: 
between hotplug and user login. libusbscanner tries to set ownership of 
the libusb device files to a guy called $CONSOLEOWNER, but if nobody is 
logged in when the hotplug event occurs (eg when the scanner is already 
plugged in at boot time), the script fails.
I had a similar problem on fedora 2, see
where you also can find my brute "fix".