dispwin: ../../src/xcb_io.c:542: _XRead: Assertion `dpy->xcb->reply_data != ((void *)0)' failed.

Binary package hint: argyll

Version: 1.0.3+dfsg1-3

Here is a description of the bug I sent to the argyll mailing list in may 2009:

On my system argyll crashed with the following output:

$ dispwin
dispwin: ../../src/xcb_io.c:542: _XRead: Assertion `dpy->xcb->reply_data
!= 0' failed.
Aborted

I was able to track it down to the call of XRRGetCrtcGamma in the
function get_displays (source dispwin.c). The function assumes that a
output in connected state has always a valid crtc entry which is not
true with my hardware.

I added a test for outi->crtc != 0 (see attached patch against argyll
1.0.3) and everything works fine. I took the idea for checking crtc from
xrandr.c.

I will attach the following information:
- output of xrandr
- Xorg server log
- patch that fixes the problem, based on ubuntu package

Other packages:
ii libxrandr2 2:1.3.0-2
ii xserver-xorg-video-ati 1:6.12.99+git20090929.7968e1fb-0ubuntu1
ii xserver-xorg 1:7.4+3ubuntu10