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From: Michael Paquier <[email protected]>
To: Kyotaro Horiguchi <[email protected]>
Cc: [email protected]
Cc: [email protected]
Subject: Re: Fix use of possible uninitialized variable retval (src/pl/plpgsql/src/pl_handler.c)
Date: Wed, 5 Jun 2024 14:04:39 +0900
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CAEudQAoDXrVNV8M9q2k4xycxuBrebh0NRPECXFa1N-Z8q-B7ww@mail.gmail.com>
	<[email protected]>

On Wed, Jun 05, 2024 at 01:12:41PM +0900, Kyotaro Horiguchi wrote:
> At Mon, 27 May 2024 11:31:24 -0300, Ranier Vilela <[email protected]> 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.

> 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 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.  :)
--
Michael


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