[petsc-users] Warning [-Wformat-overflow]

[Barry Smith]

   Also ensure filename is a sufficiently long string to hold any possible output from the format.



> On Jul 12, 2024, at 6:53 AM, Matthew Knepley <knepley at gmail.com> wrote:
> 
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> On Fri, Jul 12, 2024 at 2:26 AM Ivan Luthfi <ivanluthfi5 at gmail.com <mailto:ivanluthfi5 at gmail.com>> wrote:
>> This Message Is From an External Sender
>> This message came from outside your organization.
>>  
>> I have  warning:
>> 
>> FormatFunction.c: In function 'ComputeStiffnessMatrix':
>> FormatFunction.c:128:46: warning: '%d' directive writing between 1 and 11 bytes into a region of size between 0 and 99 [-Wformat-overflow]
>> (line128) sprintf(filename, "%sc%d_N%dM%d_permeability.log", up->problem_description, up->problem_flag, up->Nx, up->Mx)
>> 
>> do you know why this warning appear? and how to fix it.
> 
> You are writing a PetscInt into the spot for an int. You can
> 
>   1) Cast to int: 
> 
> sprintf(filename, "%sc%d_N%dM%d_permeability.log", up->problem_description, up->problem_flag, (int)up->Nx, (int)up->Mx)
> 
>   2) Use the custom format
> 
> sprintf(filename, "%sc%d_N%" PetscInt_FMT "M%" PetscInt_FMT "_permeability.log", up->problem_description, up->problem_flag, up->Nx, up->Mx)
> 
>   Thanks,
> 
>     Matt
>  
>> -- 
>> Best regards,
>> --
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
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