From: Tom Lane <tgl@sss.pgh.pa.us>
To: Daniele Varrazzo <daniele.varrazzo@gmail.com>
cc: Francisco Olarte <folarte@peoplecall.com>,
        pgsql-bugs <pgsql-bugs@postgresql.org>
Subject: Re: [PATCH] Fix segfault calling PQflush on invalid connection
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Comments: In-reply-to Daniele Varrazzo <daniele.varrazzo@gmail.com>
	message dated "Mon, 15 Aug 2022 16:57:58 +0200"
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Date: Mon, 15 Aug 2022 11:54:01 -0400
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Daniele Varrazzo <daniele.varrazzo@gmail.com> writes:
> After exercising most of the libpq API in psycopg 3, PQflush() seems
> the only one requiring a guard [1]. All the other functions seem to
> behave well when passed an "invalid connection" - aka either a NULL
> pointer or a connection in BAD status.

I went so far as to inspect every function listed in libpq/exports.txt.
All the ones that take a PGconn or PGresult check it for NULL except

PQflush
PQisnonblocking
PQdefaultSSLKeyPassHook_OpenSSL

PQisnonblocking is clearly an oversight, same as PQflush.
Maybe there is a case for not bothering to check in
PQdefaultSSLKeyPassHook_OpenSSL, on the grounds that you'd
not get that far without a connection, but I think for
consistency it should do so too.

There is not a lot of consistency about whether we insist on
the connection being in any particular "good" state.  For
some of the functions I think it's intentional that they should
still work on a failed connection, but I wonder if any of those
are likewise oversights.

			regards, tom lane