Re: [Libusb-devel] permissions problem (newbie...sorry)

[Tim R. <ti...@pr...>]

D Hutchinson wrote:
> I am developing an app on Centos Linux.  It works fine when run as root, 
> but fails when run as a non-privileged user.  The failing function is 
> usb_set_configuration() call right after a successful usb_open().  I 
> don't see how to find any finer information about what the failure is.  
> I have run "chmod 666 /dev/usb*".

That's not where USB devices live.

> Is there a way to successfully call 
> usb_set_configuration as a non-privileged user?  Is there some other 
> node in /dev that I need to change the permissions on?
>   

libusb uses the usbfs pseudo file system to talk to the device.  These
files live in /proc/bus/usb.  However, the file name changes every time
your device is plugged in (for example, /proc/bus/usb/003/004).  For
testing, you can do the chmod, but for production, you'll want something
more predictable.  For that, I suggest you look into udev.  This allows
you to write a "rule" that matches your device and triggers actions,
like assigning a more friendly device name and changing the permissions.

I, for one, would welcome "best practices" ideas from those who are more
deeply involved in Linux USB.

-- 
Tim Roberts, ti...@pr...
Providenza & Boekelheide, Inc.