finding source of segfault

Drew Parsons dparsons at
Tue Jun 13 22:34:28 PDT 2006

I'm trying to test the freetype 2.2 fix for lib/Xfont (bug #6918).  I'm
testing it with the latest xserver from git (testing against Xprt to be
precise). I'm running Debian unstable, which hasn't yet transitioned to
X11R7.1.   So I've grabbed lib/Xfixes and lib/Xfont from CVS, xserver
from git, all other libraries are still X11R7.0.  Xfixes4 is required
to build the latest xserver, and Xfont is the thing I'm really try to
test (with the freetype2.2 patch).

I get a segfault when testing.  What I do not yet know is whether it
occurs because other libraries need to be upgraded to X11R7.1, or
whether the freetype2.2 patch on lib/Xfont has affected the xserver
code, and something needs to be changed there as well (whether in
xserver/Xprint or elsewhere).

I'm writing now on the off-chance that someone might recognise the
signature of the segfault and be able to pinpoint  which lib needs to be
upgraded to X11R7.1 (or beyond).  The backtrace looks like:

#0  0x00000000 in ?? ()
#1  0x080bc2ee in compCreateWindow (pWin=0x875e6e8) at compwindow.c:600
#2  0x0808a958 in CreateWindow (wid=2097154, pParent=0x85d08d0,
    x=<value optimized out>, y=<value optimized out>, w=<value optimized
    h=<value optimized out>, bw=<value optimized out>,
    class=<value optimized out>, vmask=<value optimized out>,
    depth=8, client=0x8759880, visual=35, error=0xbfe81ae8) at
#3  0x0806d52e in ProcCreateWindow (client=0x8759880) at dispatch.c:522
#4  0x0806d72b in Dispatch () at dispatch.c:458
#5  0x0807d33d in main (argc=6, argv=0xbfe820c4, envp=0x0) at main.c:447

It comes out of my Xprt binary and is triggered by any printing (e.g.
running xphelloworld).

Does this backtrace look familiar to anyone?  compwindow.c comes from
xserver/compsite, but the xserver does not seem to use lib/Xcomposite
itself, so it's not clear to me what's going on yet.  If no one knows
already what's responsible then I'll continue by explictly testing
values in compCreateWindow to see what's null.


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