[sane-devel] Hotplug and udev files created automatically now, please test!

[Peter Christy]

On Tuesday 02 May 2006 17:40, m. allan noah wrote:
> i am confused by this- first you say that you need sane to look under
> /sys or /dev for devices, then you say that you have to alter permissions
> to get it working. which is it?

udev mounts the usbscanner under /sys In my case, under /sys/bus/usb/ and then 
a randomly variable point. However, given the relevant vendor and product 
IDs, it will automatically create a symlink in /dev and set all the relevant 
permissions.

So for example, I can make it produce a /dev/usbscanner symlink that will 
always point to the scanner, wherever it may have appeared on 
the /sys/bus/usb/ directory, and have the right permissions.

However, sane appears to be looking for the scanner 
under /proc/bus/usb/whatever, which udev cannot easily (as far as I can see) 
set the permissions. As in the /sys file system, it seems to be somewhat 
random where it pops up, from one reboot to the next, although the location 
does correspond to the location under /sys. 

Even hotplug was incapable of setting the permissions automatically, because 
although my scanner always appeared as /proc/bus/usb/002/002, hotplug 
*always* tried to set the permissions for /proc/bus /usb/001/002! This was a 
bug in hotplug that never got fixed! I bypassed it by adding 

chown root:users /proc/bus/usb/002/002
chmod 0660 /proc/bus/usb/002/002

to my rc.local file. However, this only works if the scanner always appears 
on /proc/bus/usb/002/002 Under udev alone, it doesn't. As often as not it 
appears as  /proc/bus/usb/001/003 or even something else!

I need to find some way of making sane use /dev/usbscanner to access the 
scanner rather than /proc/bus/usb/whatever. My understanding is that this is 
a very old way of doing things that only works with kernel scanner modules. 
Certainly my initial attempts in this area have met with total failure!

-- 
Pete
christy at attglobal.net