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List:       kde-core-devel
Subject:    Re: Strange crash in kmimemagic.h
From:       Wynn Wilkes <wynnw () calderasystems ! com>
Date:       2001-04-09 20:24:35
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On Friday 06 April 2001 05:55 pm, David Faure wrote:
> On Saturday 07 April 2001 00:44, Wynn Wilkes wrote:
> > Hello,
> >
> > I've been using the HEAD Branch of kde, and the KDEVELOP_1_4 branch of
> > kdevelop.  This week a strange crash started happening whenever I
> > attempted to open a file or new project.  The pertinent part of the
> > backtrace looks like:
> > #2  0x40a2e110 in KCrash::defaultCrashHandler (signal=11) at
> > kcrash.cpp:194 #3  <signal handler called>
> > #4  0x40cc483d in QString::QString () from /usr/lib/qt2/lib/libqt.so.2
> > #5  0x400c0a30 in KMimeMagicResult::mimeType (this=0x83426a0)
> >     at /opt/kde-cvs/include/kmimemagic.h:52
>
> Huh, I did quite some changes to KMimeMagic recently....
>
> > #6  0x4064cbf8 in KMimeType::findByURL (_url=@0x8342274, _mode=32768,
> >     _is_local_file=true, _fast_mode=false) at kmimetype.cpp:245
>
> Can you print out the URL it's looking at ?
> If you open Konqueror on that directory, does it crash looking at the same
> file ?
>
> > There were a couple of other situations where
> > KMimeMagicResult::mimeType() also crashed.  In trying to debug it, it
> > looked like the m_strMimeType ( a QString ) in the KMimeMagicResult class
> > was being corrupted, leading to the segfault.  This happens in the static
> > void refineResult method in kmimemagic.cpp:1958 right after line 1961.  I
> > can't see where this is happening.
>
> Any interesting debug output if you s,//kdDebug,kdDebug, in kmimemagic.cpp
> ? (it's what I do to debug kmimemagic - we don't want the calls to remain
> there because this code is quite performance-critical).
>
> I doubt KFile is to blame here - it's KMimeType that calls KMimeMagic, so
> there are too many layers in between. And I know I changed KMimeMagic
> quite much recently :} Can't see what caused this though.
I rebuilt everything this morning after updating and that crash is gone.  I 
don't understand why it was crashing- I stepped through everything in gdb and 
all the code looked good, but it always crashed when trying to create a 
QString- somehow the memory for the m_strMimeType was getting corrupted.

I'll look into it more if it ever comes back...I must have had something 
weird happening in my setup.

Wynn

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