[Valgrind-users] question about the seriousness of an error

[Edward M. <Edw...@ce...>]

Hi,

A colleague of mine has found some problems reported in his code, and he 
doesn't think that it's too serious. I would like to check that he is 
correct, and since I don't really know how valgrind works at a fine level, I 
was wondering if I could ask the list?

The error is:
==30741== Conditional jump or move depends on uninitialised value(s)
==30741==    at 0x4202D15A: __strtol_internal (in /lib/i686/libc-2.2.5.so)
==30741==    by 0x64FB7C66: LArFCALCalculatorBase::GetElectrodes() 
(/usr/include/stdlib.h:301)
==30741==    by 0x64FB14AB: LArFCAL1Calculator::LArFCAL1Calculator() 
(../src/LArFCAL1Calculator.cc:31)
==30741==    by 0x64FB1238: LArFCAL1Calculator::GetInstance() 
(../src/LArFCAL1Calculator.cc:16)


His response was that it looked like there were two char[3] arrays, but the 
last element of the array was unitialised, causing the valgrind error. He 
believed that compilers should normally initialize a character array to 
binary zero and so it shouldn't be a problem.

My understanding of valgrind was that it ran the machine code, and so if it 
reports an error then the compiler HASN'T initialize the memory at all. 

Am I correct?

Cheers,

Ed