XEVIE stuck in xcb_wait_for_reply()

[Rémi Cardona]

Hi all,

I'm trying to use XEVIE for a few tests and somehow, calls to XevieStart 
or XevieSelectInput on some Xorg servers just never return.

All my tests are done on "unstable" Gentoo systems (both x86 and amd64) 
with xserver-1.4.0.90 (with recent security patches). I'm using libX11 
with xcb support.

I have 3 test cases :
  - the xeviedemo.c test program found here [1]
  - the same code hacked to use xcb-xevie [2]
  - an OpenGL compositor

I've been able to run a Xorg instance in gdb, showing me that the 
XevieStart and XevieSelectInput do trigger Xext/xevie.c:ProcDispatch() 
correctly and that it does go back to dix/dispatch.c:Dispatch().

Basically, all seems to work fine on the server side, but my test cases 
are so simple that I'm really wondering what I'm doing wrong.

Am I hitting a bug somewhere? How can I dig deeper to see what's holding 
the calls into xcb_wait_for_reply() ?

FWIW, gdb backtrace of my compositor (identical with the other 2 test cases)

Program received signal SIGINT, Interrupt.
[Switching to Thread 0x2ae354187920 (LWP 10085)]
0x00002ae3532428c3 in __select_nocancel () from /lib/libc.so.6
Current language:  auto; currently c
(gdb) bt
#0  0x00002ae3532428c3 in __select_nocancel () from /lib/libc.so.6
#1  0x00002ae3521ccb2b in _xcb_in_read_block (c=0x62d020, buf=<value 
optimized out>, len=24483320) at xcb_in.c:248
#2  0x00002ae3521ccd73 in _xcb_in_read (c=0x62d020) at xcb_in.c:150
#3  0x00002ae3521cbc15 in _xcb_conn_wait (c=0x62d020, cond=<value 
optimized out>, vector=0x0, count=0x0) at xcb_conn.c:357
#4  0x00002ae3521cd615 in xcb_wait_for_reply (c=0x62d020, request=54, 
e=0x7fff5e7025a8) at xcb_in.c:344
#5  0x00002ae351d08af8 in _XReply (dpy=0x62c520, rep=0x7fff5e7025f0, 
extra=0, discard=0) at xcb_io.c:364
#6  0x00002ae3518a79fe in XevieSelectInput (dpy=0x62c520, event_mask=76) 
at Xevie.c:205
#7  0x0000000000410119 in CompositeServer (this=0x764690, 
display=0x62c520, screen=0, cow=4194307,
cowHandler=@0x7fff5e702870)
     at CompositeServer.cxx:67
#8  0x00000000004088e7 in mCompositor (this=0x62c470, uri=0x41e9f0 
"metisse://127.0.0.1:1",
encoding=nucleo::Image::PREFERRED)
     at mCompositor.cxx:73
#9  0x000000000040d603 in main (argc=1, argv=0x7fff5e702bf8) at 
mini-compositor.cxx:43

Thanks for any help

[1] http://people.freedesktop.org/~ajax/xevie/xevie-test.txt
[2] http://www.lri.fr/~cardona/git/xeviedemo.git

-- 
Rémi Cardona
LRI, INRIA
remi.cardona at lri.fr
remi at gentoo.org