[PATCH] Ensure DSO_FILENAME does not dereference NULL.

[pinskia@gmail.com]

> On Nov 12, 2013, at 7:24 AM, Marcus Shawcroft <marcus.shawcroft@linaro.org> wrote:
> 
> The AArch64 and ARM glibc build is currently broken for trunk gcc.
> Both builds fail with link errors for the multiple definition of
> _dl_addr_inside_object.
> 
> This is caused by the "Isolate erroneous paths optimization" patch
> recently added to gcc here:
> 
> http://gcc.gnu.org/ml/gcc-patches/2013-10/msg02648.html
> 
> One effect of this patch is to replace unreachable paths with a call to abort().

Hmm, it calls __builtin_trap shouldn't GCC back end for both arm and aarch64 support that directly instead?

Thanks,
Andrew

> 
> There is code in _dl_lookup_symbol_x() which may pass NULL to
> DSO_FILENAME().  This macro always dereferences the filename.  The
> isolate erroneous paths cod in gcc inserts an abort() in place of the
> ill defined code. The linker subsequently pulls in a bunch of code
> from libpic.a, including the alternative definition of
> _dl_addr_inside_object.
> 
> The convention elsewhere appears to be to pass "" rather than NULL.
> This patch seems obvious to me, I'll commit it tomorrow unless anyone
> objects.
> 
> * elf/dl-lookup.c (_dl_lookup_symbol_x): Pass "" instead of NULL to
> DSO_FILENAME().
> 
> Cheers
> /Marcus
> <0002-DSO_FILENAME-expects-rather-than-NULL.txt>