Bug#832607: xrandr: crash when trying to desactivate an external screen

[Julien Cristau <jcristau@debian.org>]

On Wed, Jul 27, 2016 at 15:28:00 +0200, Vincent Danjean wrote:

>   Somtimes, when trying to desactivate my external screen, I get a segfault:
> vdanjean@eyak:~$ xrandr --output VGA1 --off --output VIRTUAL1 --off --output DP-1-1 --off --output DP-1-2 --off --output DP-1-3 --off --output eDP1 --auto --primary
> Floating point exception (core dumped)
> 
That's not a segfault...

>   I'm not sure the bug comes from xrandr itself. Perhaps it is in an underlining driver, as
> I get a very suspiscous "resolution" value from xdpyinfo for example:
> vdanjean@eyak:~$ xdpyinfo  | grep -B 100 -A 20 resolution     
[...]
> screen #0:
>   dimensions:    3840x2160 pixels (0x0 millimeters)
>   resolution:    -2147483648x-2147483648 dots per inch

The divide by 0 is a bug in xrandr.  The 0mm is arguably a bug in the
driver.

Cheers,
Julien