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Re: [PATCH] Don't check ABI for _nl_default_dirname


On Sunday, December 09, 2012 13:38:41 Rich Felker wrote:
> On Fri, Dec 07, 2012 at 09:02:15PM -0800, Andi Kleen wrote:
> > From: Andi Kleen <ak@linux.intel.com>
> > 
> > As discussed in
> > http://comments.gmane.org/gmane.comp.lib.glibc.alpha/24671
> > 
> > The ABI of _nl_default_dirname depends on the prefix glibc is
> > compiled with. For glibcs with non standard prefix
> > _nl_default_dirname changes, which causes the ABI check in make
> > check to fail.
> 
> This is a fundamentally broken part of the ABI that should be fixed.
> _nl_default_dirname should be deprecated (with whatever tricks to
> prevent new programs from linking to it) and replaced with
> _nl_default_dirname_ptr that's a pointer instead of an array.
> Exporting arrays that will be subject to copy relocations is deep into
> the realm of Considered Harmful.
> 
> If _nl_default_dirname is declared anywhere in the headers, it could
> be remapped to generate a reference through the
> _nl_default_dirname_ptr pointer instead.

Is _nl_default_dirname really used anywhere? I just did a grep on my 
system and did not get a single match besides libc itself,

Still I fear there might be broken programs but why not change the ABI 
that this is not exported anymore for newly build applications and only 
for old one?

Andreas
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