Re: Fix use of possible uninitialized variable retval (src/pl/plpgsql/src/pl_handler.c)

Em qua., 5 de jun. de 2024 às 02:04, Michael Paquier <michael(at)paquier(dot)xyz>
escreveu:

> On Wed, Jun 05, 2024 at 01:12:41PM +0900, Kyotaro Horiguchi wrote:
> > At Mon, 27 May 2024 11:31:24 -0300, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
> wrote in
> >> The function *plpgsql_inline_handler* can use uninitialized
> >> variable retval, if PG_TRY fails.
> >> Fix like function*plpgsql_call_handler* wich declare retval as
> >> volatile and initialize to (Datum 0).
>
> You forgot to read elog.h, explaining under which circumstances
> variables related to TRY/CATCH block should be marked as volatile.
> There is a big "Note:" paragraph.
>
> It is not the first time that this is mentioned on this list: but
> sending a report without looking at the reason why a change is
> justified makes everybody waste time. That's not productive.
>
Of course, this is very bad when it happens.

>
> > If PG_TRY fails, retval is not actually accessed, so no real issue
> > exists. Commit 7292fd8f1c changed plpgsql_call_handler() to the
> > current form, but as stated in its commit message, it did not fix a
> > real issue and was solely to silence compiler.
>
> This complain was from lapwing, that uses a version of gcc which
> produces a lot of noise with incorrect issues. It is one of the only
> 32b buildfarm members, so it still has a lot of value.
>
I posted the report, because of an uninitialized variable warning.
Which is one of the most problematic situations, when it *actually exists*.

> > I believe we do not need to modify plpgsql_inline_handler() unless
> > compiler actually issues a false warning for it.
>
> If we were to do something, that would be to remove the volatile from
> plpgsql_call_handler() at the end once we don't have in the buildfarm
> compilers that complain about it, because there is no reason to use a
> volatile in this case. :)
>
I don't see any motivation, since there are no reports.

best regards,
Ranier Vilela