dlsym() may return an undefined symbol

[Joakim Tjernlund]

Cedric

Here is a patch that will return a valid ptr for malloc2. Please test.

  Jocke

On Mon, 2007-01-15 at 19:55 +0100, Cédric Hombourger wrote:
>  Hi there,
> 
> Many thanks for your support
> 
> It seems that 0.9.29 (svn) and 0.9.28 indeed returns a NULL pointer and this behaviour (while different from glibc) is perfectly fine with our application.
> 
> I am willing to test your fix for (2) if that helps.
> 
> Cedric
> 
> -----Original Message-----
> From: Joakim Tjernlund [mailto:joakim.tjernlund at transmode.se] 
> Sent: Sunday, January 14, 2007 10:03 PM
> To: Cédric Hombourger; uclibc at uclibc.org
> Subject: RE: dlsym() may return an undefined symbol
> 
>  
> 
> > -----Original Message-----
> > From: uclibc-bounces at uclibc.org 
> > [mailto:uclibc-bounces at uclibc.org] On Behalf Of Joakim Tjernlund
> > Sent: den 12 januari 2007 16:26
> > To: Cédric Hombourger; uclibc at uclibc.org
> > Subject: RE: dlsym() may return an undefined symbol
> > 
> > Hi Cedric
> > 
> > Had a quick look at this and it migth be that the problem is easily
> > fixed by this:
> > Index: ldso/libdl/libdl.c
> > ===================================================================
> > --- ldso/libdl/libdl.c	(revision 17166)
> > +++ ldso/libdl/libdl.c	(working copy)
> > @@ -442,7 +442,7 @@
> >  		}
> >  	}
> >  
> > -	ret = _dl_find_hash((char*)name, handle, NULL, 0);
> > +	ret = _dl_find_hash((char*)name, handle, NULL, 
> > ELF_RTYPE_CLASS_PLT);
> >  
> >  	/*
> >  	 * Nothing found.
> > 
> > However I am far from sure about this. Especially on other 
> > arch's than MIPS since
> > on MIPS type_class is always equal to ELF_RTYPE_CLASS_PLT for 
> > all other lookups
> > 
> > Would be great if you could test this on MIPS and x86.
> > 
> >  Jocke
> > 
> > > -----Original Message-----
> > > From: Cédric Hombourger [mailto:chombourger at nexwave-solutions.com] 
> > > Sent: 12 January 2007 14:10
> > > To: Joakim Tjernlund; uclibc at uclibc.org
> > > Subject: RE: dlsym() may return an undefined symbol
> > > 
> > > 
> > > Hello Jocke, thanks for your quick response and apologies for 
> > > the HTML post that I did. Yes I am more than aware that 
> > > 0.9.27 is rather old but we unfortunately have to integrate 
> > > our S/W component loader and runtime into a Linux-based 
> > > solution provided by a thirdparty (who delivers to us 
> > > binaries of the linux kernel, uclibc 0.9.27, and of their 
> > > software stack). We will push for an upgrade to 0.9.28... 
> > > 
> > > I have reproduced this behaviour with a SVN checkout of 
> > > uclibc from yesterday. Unfortunately, if I turn on traces 
> > > then I get a segv (that I will investigate). You will find 
> > > attached the test program that I used on mipsel-linux-uclibc 
> > > and below are the traces that I got with LD_DEBUG=all 
> > > defined. Note that the test program works just fine on 
> > > mipsel/glibc 2.3.2 (dlsym() returns the same pointer for both 
> > > calls) while on uclibc, the pointer returned by the second 
> > > dlsym() is a pointer to .MIPS.stubs resolving a completely 
> > > different symbol. 
> > > 
> > > Again thank you for your response, and please let me know if 
> > > there is something else you need.
> 
> Hi again
> 
> When testing this on PPC I get a NULL ptr for malloc2 and
> having looked more at this issue I see that the current libdl impl.
> don't search libs that is already loaded(libc is this case).
> So I think there is two problems here:
> 1) You should get a NULL ptr back with current SVN impl. and .28
> 2) dlopen needs to be fixed to actually add the dependent libs to the
>    search list even if these libs are already loaded.
> 
> MIPS is a very odd animal when it comes to dynamic linking so you
> you may have a MIPS specific bug for 1)
> 
> for 2) I got something that should fix the problem for
> SVN and probably .28 as it is very similar to SVN. Got to clean it
> up a little first.
> 
>  Jocke
> 
> 
> 
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