libusb:error [__open_sysfs_attr], errno=2

[dsd]

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On linux-2.6.26 a call to libusb_get_device_list gives the following error
on the console:

libusb:error [open_sysfs_attr] open /sys/bus/usb/devices/4-1/descriptors
failed ret=-1
errno=2

and the functions returns -1. The file "descriptors" does not exist in all
usb directories.
I searched through the directory /sys/bus/usb/devices and found out that a
few folder
contains the "descriptors" file and other not.
It seems that the new kernel release doesn't create this file for all
devices. I think we
have to fall back to usbfs in order to get the descriptor.

On linux-2.6.23.1 this error doesn't occur.

This is a kernel bug but libusb should be more resilient.