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Re: Hot Standby conflict resolution handling

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Abhijit Menon-Sen <ams(at)2ndQuadrant(dot)com>,Stephen Frost <sfrost(at)snowman(dot)net>,Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Hot Standby conflict resolution handling
Date: 2013-01-17 10:47:44
Message-ID: 20130117104744.GA4314@awork2.anarazel.de (view raw or flat)
Thread:
Lists: pgsql-hackers
On 2013-01-17 01:38:31 -0500, Tom Lane wrote:
> But having said that ... are we sure this code is not actually broken?
> ISTM that if we dare not interrupt for fear of confusing OpenSSL, we
> cannot safely attempt to send an error message to the client either;
> but ereport(FATAL) will try exactly that.

You're absolutely right.

ISTM, to fix it we would have to either provide a COMERROR like facility
for FATAL errors or just remove the requirement of raising an error
exactly there.
If I remember what I tried before correctly the latter seems to involve
setting openssl into nonblocking mode and check for the saved error in
the EINTR loop in be-secure and re-raise the error from there.

Do we want to backport either - there hasn't been any report that I
could link to it right now, but on the other hand it could possibly
cause rather ugly problems (data leakage, segfaults, code execution
aren't all that improbable)?

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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