RTLD_GLOBAL again (was Re: kdeutils/kregexpeditor/test)

[Malte Starostik]

Am Sunday 21 April 2002 01:32 schrieb Malte Starostik:
> Am Sunday 21 April 2002 01:00 schrieb Lubos Lunak:
> > On Saturday 20 April 2002 23:42, Martijn Klingens wrote:
> > > On Saturday 20 April 2002 21:37, Michael Matz wrote:
> > > I think it is a good idea to promote the use of namespaces. If we start
> > > now then maybe by the time of KDE 4.0 we can decide whether we can
> > > start loading all libs with RTLD_GLOBAL. Till that time qt_cast is the
> > > way to go IMO.
> >
> >  Here I originally wanted to say that KDE4.0 is too long and such, but
> > now after thinking about, if the only difference will be
> > RTLD_LOCAL<->RTLD_GLOBAL and qt_cast<->dynamic_cast, then fine. This in
> > fact means that we will be slowly moving to state when we will be
> > pretending that we actually use RTLD_GLOBAL, just we won't yet.
>
> I just found another issue: deginer will crash on startup when
> kdewidgets.so is installed. This is what happens:
> designer loads the plugins from the plugin directory. First it tries them
> as EditorPlugin. Since kdewidgets.so isn't such a thing, but a
> QWidgetPlugin, it unloads the lib again (trying as QWidgetPlugin happens
> later). This unloading causes a crash.
> I stripped anything from kdewidgets.cpp that needs kdeui and linked only
> against libkdecore, then at least the unload works (of course kdewidgets
> isn't of any use then). As soon as libkdeui is linked in, the crash
> appears. The program below reproduces the crash (sorry for the hardcoded
> path). When libqt-mt is _not_ linked in, the crash only happens on exit, as
> soon as it is linked, it happens on the dlclose() call.
>
> #include <dlfcn.h>
> #include <iostream>
>
> int main( int argc, char* argv[] )
> {
>     using std::cerr;
>     using std::endl;
>     cerr << "Loading kdewidgets.so..." << endl;
>     void* lib = dlopen(
> "/usr/local/kde/lib/kde3/plugins/designer/kdewidgets.so", RTLD_LAZY );
>     cerr << "Done. Unloading..." << endl;
>     dlclose( lib );
>     cerr << "Done. Exiting..." << endl;
> }
>
> When RTLD_GLOBAL is added to the dlopen() options, the crash goes away. I
> don't think this bt is really accurate, but anyway:
> #0  0x00000000 in ?? ()
> #1  0x412aac8f in __static_initialization_and_destruction_0
> (__initialize_p=1094307840,
>     __priority=1073821528) at ../../../kdelibs/kdecore/kdebug.cpp:168
> #2  0x412aace8 in _GLOBAL__D__Z6perrorR10kdbgstream () at
> ../../../kdelibs/kdecore/kdebug.cpp:70
> #3  0x412975b7 in __do_global_dtors_aux () from
> /usr/local/kde/lib/libkdecore.so.4
> #4  0x4138c519 in _fini () from /usr/local/kde/lib/libkdecore.so.4
> #5  0x408db773 in _dl_close () from /lib/libc.so.6
> #6  0x408db460 in _dl_close () from /lib/libc.so.6
> #7  0x40021efa in dlclose () from /lib/libdl.so.2
> #8  0x4000ada3 in _dl_catch_error (objname=0x804ad10, errstring=0x804ad14,
>     operate=0x40021ee0 <dlclose+60>, args=0x80a2928) at dl-error.c:152
> #9  0x4002221b in dlerror () from /lib/libdl.so.2
> #10 0x40021ec4 in dlclose () from /lib/libdl.so.2
> #11 0x08048a60 in main (argc=1, argv=0xbffff714) at foo.cpp:23
> #12 0x407dc2c7 in __libc_start_main () from /lib/libc.so.6
>
> so basically, KDE widget support doesn't work in designer with gcc 3.1 as
> long as Qt opens plugins with RTLD_GLOBAL :-(((
Sorry, this should have read "as long as Qt opens plugins with_out_ 
RTLD_GLOBAL".

-- 
Malte Starostik
PGP: 1024D/D2F3C787 [C138 2121 FAF3 410A 1C2A  27CD 5431 7745 D2F3 C787]