[ipxe-devel] [PATCH] [efi] Simplify diagnostic for NULL handle

[Bruce Rogers]

>>> On 1/25/2019 at 10:26 AM, Michael Brown <mcb30 at ipxe.org> wrote:
> On 25/01/2019 16:53, Bruce Rogers wrote:
>> Compiling with GCC 9 now warns as follows:
>> interface/efi/efi_debug.c:334:3: error: ‘%s’ directive argument is null 
> [-Werror=format-overflow=]
>>    334 |   printf ( "HANDLE %s could not retrieve protocols\n",
>>        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>    335 |     efi_handle_name ( handle ) );
>>        |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> cc1: all warnings being treated as errors
>> 
>> Simplify this diagnostic by simply indicating a <NULL> has been
>> passed as a handle.
> 
> I'd prefer not to have to work around that on an instance-by-instance 
> basis; we explicitly allow NULL as a value for a %s format specifier, 
> and there are multiple other code paths that will do this.
> 
Understandable. This one seemed to be the only one noticed by the compiler
however, when I build with a simple make -C src.

> Is there a way to inform GCC 9 that NULL is allowed as a %s value?
>
I don't know if there is. There is a -Wnonnull, but we probably don't
want to do that.
 
> If not, then does marking efi_handle_name() as noinline fix the warning?
> 

Yes, that does indeed avoid this warning, and the object size changes only
slightly. Do you want me to send a patch for that?

Bruce