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List:       kde-multimedia
Subject:    Re: Bug#21233: noatun startup crash
From:       Stefan Westerfeld <stefan () space ! twc ! de>
Date:       2001-03-02 11:08:27
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   Hi!

The backtrace is aRts way of telling you that you are dereferencing an object
which you didn't really assign.

In the following code:

   Arts::Equalizer eq;
   eq.preamp(0);

aRts will try to lazycreate (assign an implementation for Arts::Equalizer to
eq, because you didn't assign anything yet) eq in the second line. So it
seems that EQBACK in equalizer.cpp is in that "lazycreateme" state, maybe
because initArts didn't run completely, and you try to use it. If you don't
want to have lazycreate, you can do

   Arts::Equalizer eq = Arts::Equalizer::null();

but then again, calling

   eq.preamp(0)

on a null object will result in a crash, too ;-). So simply make sure that
you don't do any method invocations on uninitialized objects (i.e. simply
do not call things like EQBACK->preamp(0), if Engine::initArts was not
sucessful).

   Cu... Stefan

On Thu, Mar 01, 2001 at 08:34:13PM -0800, Charles Samuels wrote:
> 
> Arts is weird, this happens only once on login sometimes, we still are trying 
> to find it, but it's not easy :)
> 
> On Thursday 01 March 2001 04:35 pm, you wrote:
> > Package: noatun
> > Version: KDE 2.1.0
> > Severity: normal
> > Installed from:    Compiled From Sources
> > Compiler:          gcc 2.95.2
> > OS:                Linux
> > OS/Compiler notes: Linux kernel 2.4 with ALSA 0.5.10 sound drivers,
> > everything compiled from sources
> >
> > The first time I tried to start noatun, it crashed. The backtrace is below.
> > The second, third and fourth time it started OK. Maybe some kind of race
> > condition?
> >
> > [New Thread 1024 (runnable)]
> > 0x40e42ee9 in __wait4 () from /usr/local/lib/libc.so.6
> > #0  0x40e42ee9 in __wait4 () from /usr/local/lib/libc.so.6
> > #1  0x40e9f658 in __DTOR_END__ () from /usr/local/lib/libc.so.6
> > #2  0x401f910a in waitpid (pid=11608, stat_loc=0x0, options=0)
> >     at wrapsyscall.c:134
> > #3  0x406b7c30 in KCrash::defaultCrashHandler ()
> >    from /usr/kde2.1/lib/libkdecore.so.3
> > #4  <signal handler called>
> > #5  0x40de18d1 in __kill () from /usr/local/lib/libc.so.6
> > #6  0x401f79aa in pthread_kill (thread=1024, signo=6) at signals.c:65
> > #7  0x401f7e49 in raise (sig=6) at signals.c:226
> > #8  0x40de2c42 in abort () at ../sysdeps/generic/abort.c:88
> > #9  0x40ddbc5a in __assert_fail () at assert.c:59
> > #10 0x40065ecf in Arts::Equalizer_base::_create ()
> >    from /usr/kde2.1/lib/libnoatun.so.0
> > #11 0x400687e3 in Arts::Equalizer::_Creator ()
> >    from /usr/kde2.1/lib/libnoatun.so.0
> > #12 0x4006f96f in Equalizer::setPreamp () from
> > /usr/kde2.1/lib/libnoatun.so.0 #13 0x4006f470 in Equalizer::init () from
> > /usr/kde2.1/lib/libnoatun.so.0 #14 0x40052b4d in NoatunApp::NoatunApp ()
> > from /usr/kde2.1/lib/libnoatun.so.0 #15 0x8049b32 in main ()
> > #16 0x40ddb9a1 in __libc_start_main (main=0x804999c <main>, argc=7,
> >     argv=0xbffff79c, init=0x8049578 <_init>, fini=0x804a798 <_fini>,
> >     rtld_fini=0x40009eb4 <_dl_fini>, stack_end=0xbffff794)
> >     at ../sysdeps/generic/libc-start.c:92
> >
> >
> > (Submitted via bugs.kde.org)
> > (Called from KBugReport dialog. Fields Application, KDE Version, OS,
> > Compiler, E-Mail manually changed)
> 
> -- 
> Charles Samuels <charles@kde.org>
> K Desktop Environment
> "The people. Could you patent the sun?"
>  -- Jonas E. Salk, when asked who owned the patent on his polio vaccine.
> _______________________________________________
> Kde-multimedia mailing list
> Kde-multimedia@master.kde.org
> http://master.kde.org/mailman/listinfo/kde-multimedia

-- 
  -* Stefan Westerfeld, stefan@space.twc.de (PGP!), Hamburg/Germany
     KDE Developer, project infos at http://space.twc.de/~stefan/kde *-         
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