This is the mail archive of the
mailing list for the glibc project.
Crash when using dlmopen
- From: Mike Hearn <mike at plan99 dot net>
- To: libc-alpha at sources dot redhat dot com
- Date: Wed, 29 Jun 2005 17:21:48 +0100
- Subject: Crash when using dlmopen
I have a program that links against libSDL, which dlopens the aRts sound
server library (libartsc.so.0) which in turns dlopens various other
I'm experimenting with using an LD_PRELOAD module to force the first
dlopen of libartsc.so.0 into a new namespace using dlmopen instead of
regular dlopen. That's because otherwise there are C++ symbol conflicts
between libstdc++.so.5 which is what the game uses and libstdc++.so.6
which is what my copy of arts uses. The symbol versioning is not enough to
stop this (there is a bug in GCC bugzilla about it).
The first dlmopen seems to work OK judging by the LD_DEBUG traces, but
when libartsc (now in namespace 1) tries to dlopen another library it
crashes somewhere inside the dynamic linker.
I tried to get a backtrace of this crash, the best I could get was one
that indicated the crash happened inside dlopen_doit, which is quite early
on and unlikely to be the real source of the bug. GDB was totally useless,
it seems completely broken on FC4 - even with the debuginfo packages
installed it does not give a real backtrace of most apps I try it with. I
had to use catchsegv and valgrind instead.
Does anybody have some ideas on why this might crash? Am I mis-using the
Also, I tried using RTLD_DEEPBIND as I thought that would be similar to
grouped fixup as implemented on Solaris. But it seems that this option
does not do what I thought it did - symbols are still bound back to the
original binary even though the executable is not "deeper" in the tree
than that library.
Can anybody explain why RTLD_DEEPBIND is not doing as I expected?