bin/129963: [newusb] usbconfig(8) fails with misleading error when run as a normal user

[Garrett Cooper]

On Tue, Jan 6, 2009 at 10:32 AM, Hans Petter Selasky <hselasky at c2i.net> wrote:
> On Saturday 03 January 2009, Volker wrote:
>> On 01/03/09 01:35, Hans Petter Selasky wrote:
>> > On Wednesday 31 December 2008, vwe at freebsd.org wrote:
>> >> Synopsis: [newusb] usbconfig(8) fails with misleading error when run as
>> >> a normal user
>> >>
>> >> Responsible-Changed-From-To: freebsd-bugs->freebsd-usb
>> >> Responsible-Changed-By: vwe
>> >> Responsible-Changed-When: Wed Dec 31 12:55:52 UTC 2008
>> >> Responsible-Changed-Why:
>> >> reassign
>> >>
>> >> http://www.freebsd.org/cgi/query-pr.cgi?pr=129963
>> >
>> > Hi,
>> >
>> > "usbconfig" will only show USB devices which the user has access to.
>> >
>> > What should be the correct display message when no devices are accessible
>> > due to innsufficient permissions?
>> >
>> > --HPS
>>
>> Hans,
>>
>> what about "access denied" or "insufficient privileges"?
>>
>> Someone might have a better idea but everything should be better than
>> silently refusing to do anything.
>>
>> Volker
>
> Is this Ok:
>
> http://perforce.freebsd.org/chv.cgi?CH=155731
>
> --HPS

Eh? I still think that strerror or something along those lines would
be more helpful.

You could also do

if (getuid() != 0) {
    errx(1, "Cluebat -- you might not be able to read the usb devices
if you're not root");
}

or...

struct stat usb_s;

int fd = open(..., O_RDONLY /* blah, blah... */);

if (fd == -1) {
    errx(1, "Does the file -- %s -- exist?", file);
}

if (fstat(fd, &usb_s) == -1) {
    errx(1, "Couldn't stat the file: %s", file);
}

if (!S_IRUSR(usb_s.st_mode) && !S_IRGRP(usb_s.st_mode) &&
!S_IROTH(usb_s.st_mode)) {
    errx(1, "File not readable (do you have read permissions?)");
}

/* Continue on merry way reading devices; maybe use strerror(3) for
more intuitive error messages? */

Thoughts?
-Garrett