Re: [patch] pg_dump/pg_restore zerror() and strerror() mishap

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Vladimir Kunschikov <kunschikov(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [patch] pg_dump/pg_restore zerror() and strerror() mishap
Date: 2017-07-28 18:19:13
Message-ID: 20170728181913.owfihtuye2ki6agv@alvherre.pgsql
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Vladimir Kunschikov wrote:
> >This "maxlen" business and the fallback error message are
> >strange. We have roughly equivalent code in pg_basebackup.c
> >which has been working since 2011
> >Perhaps you can drop the memchr/fallback tricks and adopt the
> >pg_basebackup coding? Or is there a specific reason to have
> >the memchr check?
>
> Ofcourse that tricks can be dropped, function will be much prettier.
> 'Tricks' were made to pass some strict internal tests.

Well, if there are cases which cause zlib to return a message that
causes a crash when printing it or some other problem, then let's use
your version both in this new code and in pg_basebackup. Do these cases
really exist?

> Initially I used exactly that function from pg_basebackup.c:
> https://github.com/kunschikov/postgres/commit/15e9fda6df51cf17c0b0a4f201ee0f93cf258de9#diff-98e3f8ce5d6e87950dd66e4c8bdedb21R713
> It was rewritten for the sake of somewhat exaggerated security.
> Version #5 in attachment.

I'd rather have all the security we can get, so before dropping those
protections, let's make sure they are useless.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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