[PATCH] libio: Avoid _allocate_buffer, _free_buffer pointers [BZ #23236]

[Florian Weimer]

On 05/30/2018 06:36 PM, Carlos O'Donell wrote:
>> -  new_f->fp._sf._s._allocate_buffer = (_IO_alloc_type) malloc;
>> -  new_f->fp._sf._s._free_buffer = (_IO_free_type) free;
>> +  new_f->fp._sf._s._allocate_buffer_unused = (_IO_alloc_type) malloc;
>> +  new_f->fp._sf._s._free_buffer_unused = (_IO_free_type) free;
> Do we have to assign malloc/free to these? Why not just a static value of '1'?
> It would make it more clear that they are unused and crash. Or is it possible
> that they could get used by legacy code?

Yes, it is possible that they are used from 90s libstdc++ and similar 
code.  Having valid function pointers there helps with compatibility, I 
think.

Thanks,
Florian