svn commit: r265367 - head/lib/libc/regex

Andrey Chernov ache at
Mon May 5 21:40:12 UTC 2014

On 05.05.2014 22:28, David Chisnall wrote:
> On 5 May 2014, at 18:42, Andrey Chernov <ache at> wrote:
>> Please don't commit OpenBSD errors. Now you mix calloc() with the
>> realloc() for the same variable later which makes calloc() zeroing
>> pointless and waste of CPU.
> The purpose of calloc() here is not (primarily) to get the zero'd size, it's to get the overflow-checking behaviour for calloc.  

It is better to avoid using undocumented intrinsic knowledge of standard
function particular implementation, this is unportable at least and hard
to understand too.
Moreover, choosing some standard function just due to its arcane side
effect is semantically incorrect.
If you need bounds checking, you can either making it transparent from
the library code point of view (preferred) or use literal visible
methods (pragma, online function, etc).

> The uses of realloc() later do still potentially overflow, as they follow the realloc(pointer, size * sizeof(type)) antipattern.  

The code can become completely mess if not follows simple strategies above.


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