Re: lsusb omits some devices and (apparently) cannot be fixed

On Fri, Sep 14, 2007 at 12:17:17AM +0200, Aurelien Jarno wrote:
> Karl O. Pinc a ?crit :
> > Hello,
> > 
> > lsusb silently ignores at least some permission errors, resulting in
> > no output for the device to which there are no permissions.  I have it
> > on the authority of the Debian lsusb maintainter that this cannot be
> > fixed in the application.  Therefore there is a problem in the kernel
> > or the USB code that needs fixing so I'm reporting it here.  Please let
> > me know if I should report somewhere else.
> > 
> > Something somewhere is silently ignoring permission violations and the
> > result is that lsusb must always be run as root or the results cannot
> > be trusted because there is no way to know when all devices are shown
> > and when not.  (In an SELinux environment the problem may well be
> > worse and lsusb can _never_ be trusted.)  Of course lsusb should not
> > show details about devices to which the user has no permissions, but
> > it should show a permission violation.  Silently ignoring permission
> > errors and pretending these these devices do not exist is not
> > unix-like.  lsusb is violating the principal of least suprise.
> > 
> > If lsusb can detect that a device exists, and it should because the
> > device is visible in the /dev hierarchy, it should be able to tell
> > that it can't get any information about the device and issue an error,
> > just like cat does when it tries to read a file without permission or
> > ls does when it tries to read a directory or follow a symlink and
> > there's no permission.
> 
> As already explained, lsusb does not parse /dev, but uses libusb for
> that.

libusb uses /dev on "modern" versions of Linux :)

thanks,

greg k-h

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