Re: Why valgrind can't see this error?

Hi John,

On 2021-09-03 6:53 p.m., John Reiser wrote:
> On 9/3/21 12:31 PM, Eric Chamberland wrote:
>> Hi,
>>
>> I have a simple test and valgrind seems to not see the error:
>>
>> cat fread.cc && clang++ -o fread fread.cc && valgrind ./fread
>> #include <iostream>
>> #include <stdio.h>
>> #include <stdlib.h>
>>
>> int main(int argc, char ** argv){
>>      int lA {1};
>>      FILE * f = fopen ( argv[0] , "rb" );
>>      fread(&lA,2*sizeof(int),1,f);
>>      std::cout << "Hello: "<< lA << std::endl;
>>      return 0;
>> }
>
> This report is interesting only because it is a bad example:
> it does not specify what is the supposed error.
> If you don't say what you believe it is, then how are valgrind 
> developers to know?

Yes, indeed, sorry for not giving a good example!

>
> Besides, the "memcheck error" is covered in the valgrind FAQ.
> Look it up in paragraph "4.6.  Why doesn't Memcheck find ..."

Ok, thanks, the answer was there : 
https://valgrind.org/docs/manual/faq.html#faq.overruns

> The second and third errors are the logic errors of not checking
> the return value of fopen and fread.
> The fourth error is not documenting the expected invocation command line.
> The fifth error is not checking argc.
> The sixth error is not documenting the expected format of the input file.
> Are you sure that you really are a programmer?

I am happy with your answer, no need to dive into this: you helped 
someone! :)

Thanks again John!

Eric

>
>
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-- 
Eric Chamberland, ing., M. Ing
Professionnel de recherche
GIREF/Université Laval
(418) 656-2131 poste 41 22 42



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