Re: [Valgrind-users] uninitialised value(s) - after explicit memset to 0 ??

[David C. R. <dra...@su...>]

On 03/10/2015 08:07 PM, David Chapman wrote:
> On 3/10/2015 5:21 PM, David C. Rankin wrote:
>> All,
>>
>>     I have an issue with valgrind-3.8.1 (openSuSE 13.1 x86_64) reporting the
>> error:
>>
>> Conditional jump or move depends on uninitialised value(s)
>>
>>     The error stems from reallocation of a new block of memory. The error is
>> triggered when iterating over the reallocated pointer array into the reallocated
>> block, despite explicitly setting/initializing values of the new pointers to 0
>> with memset (equivalent to the original allocation with calloc).
>
> Not quite.  calloc() gets the size of the object being cleared in addition to
> the number of objects, while memset() gets only the size in bytes.  You need to
> multiply cmax by sizeof(*slines), as you did for the realloc() call.  (Of
> course, "slines + cmax" on the same line of code is pointer arithmetic, so it
> automatically performs this multiplication.  C does have its warts.)
>

Hah!, Thank you David!

(smacks self, places pointed circular hat on head, and turns sadly to face the 
corner ;-)

   Sheeze, I can't believe I walked right into that one! Thanks for solving a 
'forest for the trees issue.'  I could have looked at that for 2-days and never 
snapped to the omission.

   Thanks

-- 
David C. Rankin, J.D.,P.E.