[mpich-discuss] Mpich failing electric-fence check

[Rob Latham]

On 03/07/2014 09:25 AM, Jed Brown wrote:
> Matthieu Dorier <matthieu.dorier at irisa.fr> writes:
>> ElectricFence Aborting: Allocating 0 bytes, probably a bug.
>
> I would argue that ElectricFence is wrong here.  The standard guarantees
> that malloc(0) succeeds and it is useful to simplify code and to test
> for matching free in cases where a positive size is rare.

It wouldn't suprise me to find ElecritcFence buggy.  It was a great tool 
back in the day but Perens stopped maintaining it a decade ago, and 
there seem to be some half-hearted attempts by the community to keep it 
active (debian has some updates from... somewhere. 
http://duma.sourceforge.net/ might work?

I think everyone around here uses valgrind anyway.

==rob



>
> C99 §7.20.3: If the size of the space requested is zero, the behavior is implementation-
> defined: either a null pointer is returned, or the behavior is as if the size were some
> nonzero value, except that the returned pointer shall not be used to access an object.
>
> Either way, the returned pointer can be passed to free.  Are you aware
> of current malloc implementations which violate the above?
>
>
>
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-- 
Rob Latham
Mathematics and Computer Science Division
Argonne National Lab, IL USA