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List:       licq-devel
Subject:    Re: [Licq-devel] Re: Problem with KDE Malloc
From:       Paulo Dias <pcd () ieg ! com ! br>(by way of Paulo Dias <pcd () ieg ! com ! br>)
Date:       2002-07-25 11:46:13
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On Wednesday 24 July 2002 22:21, Jon Keating wrote:
> On Wednesday 24 July 2002 12:30 pm, Lubos Lunak wrote:
> > On Tuesday 23 July 2002 03:07, Jon Keating wrote:
> > > On Sunday 21 July 2002 02:04 pm, Lubos Lunak wrote:
> > > >  I think I understand what the problem is. Maybe a bit tough to solve
> > > > though. The reason for the crash is quite simple. LICQ binary has its
> > > > own malloc(), coming from libc, and kdelibs have their own
> > > > (different) malloc(). After dlopening the KDE GUI module, functions
> > > > in the module use different malloc() than those in the main binary,
> > > > and this leads to crash (I think it should only crash if the module
> > > > tries to free something allocated by the binary or vice versa, but
> > > > apparently it happens).
> > >
> > > Ahh, that makes sense.
> >
> > [snip]
> >
> > > So obviously, that is not correct.  Anymore ideas?
> >
> >  Hmm, yes, -Wl,--export-dynamic wasn't a correct solution, I forgot that
> > malloc() is in libc and not in the binary. But I think I have the right
> > solution now. There are actually more ways to solve the problem.
> >
> >  When the dynamic loader resolves symbols, it searches all the libraries
> > in the link order, until it finds the symbol. For licq with KDE plugin,
> > the libraries are like this:
> >
> >  licq binary | kde-licq plugin | kdelibs | qt | ... | libc
> >
> >  There are two malloc() implementation, one in libc, the other in
> > kdelibs. When the plugin is not yet loaded, items 2-4 are not there yet,
> > so when searching from left to right, malloc() is found only in libc.
> > When the plugin is dlopened, the search goes again from left to right,
> > but this time malloc() is found already in kdelibs ... => trouble.
> >
> >  There are three solutions how to make the plugin use the same malloc()
> > as the binary :
> > - remove malloc() from kdelibs - I don't think there are enough reasons
> > to make me do this
> > - add malloc() to the binary - both the binary and the plugin will use
> > this malloc() (don't forget -Wl,--export-dynamic in this case). You can
> > just take kdelibs/kdecore/malloc and use it, if you want.
> > - add another malloc() to the plugin, that will skip the faster malloc()
> > in kdelibs and use the libc one - see the attached patch and source, they
> > belong to licq/plugins/qt-gui/src. Probably the easiest solution.
>
> I'm using the 3rd option since I did not want to put KDE's malloc() into
> the licq binary.  The latest CVS has your patch for the code.  The only
> concern I have is on systems that don't have libc.so or libc.so.6.  Is this
> anything to be concerned about?
>
> Thanks!
>
> Jon
>
> ______________________________________________________________
> Jon Keating		                                           ICQ #16325723
> jon@licq.org		                                           GPG ID: 0x2290A71F
> emostar on irc.openprojects.net
>
>
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it solved all the bugs i was experiencing, thanks for the patch jon, licq
works flawlessly now:)))

best regards...

--
Paulo Dias
pcd@ieg.com.br
pmcd@terra.com.br
icq: 15544538
WebProgrammer/WebDesigner



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