Re: [PATCH] add relation and block-level filtering to pg_waldump

On 24.03.22 11:57, Peter Eisentraut wrote:
> On 23.03.22 23:54, Thomas Munro wrote:
>>> That's because ForkNum is a signed type.  You will probably succeed if
>>> you use "%d" instead.
>>
>> Erm, is that really OK?  C says "Each enumerated type shall be
>> compatible with char, a signed integer type, or an
>> unsigned integer type. The choice of type is implementation-defined,
>> but shall be capable of representing the values of all the members of
>> the enumeration."  It could even legally vary from enum to enum,
>> though in practice most compilers probably just use ints all the time
>> unless you use weird pragma pack incantation.  Therefore I think you
>> need an intermediate variable with the size and signedness matching the
>> format string, if you're going to scanf directly into it, which
>> David's V6 did.
> 
> An intermediate variable is probably the best way to avoid thinking 
> about this much more. ;-)  But note that the committed patch uses a %u 
> format whereas the ForkNum enum is signed.
> 
> Btw., why the sscanf() instead of just strtol/stroul?

Or even:  Why are we exposing fork *numbers* in the user interface? 
Even low-level tools such as pageinspect use fork *names* in their 
interface.