Date: Tue, 28 Feb 2023 20:36:03 -0800
From: Nathan Bossart <nathandbossart@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Thomas Munro <thomas.munro@gmail.com>,
	Michael Paquier <michael@paquier.xyz>,
	Robert Haas <robertmhaas@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
	Fujii Masao <fujii@postgresql.org>,
	Postgres hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: stopgap fix for signal handling during restore_command
Message-ID: <20230301043603.GD1453450@nathanxps13>
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On Sun, Feb 26, 2023 at 12:12:27PM -0800, Andres Freund wrote:
> On 2023-02-26 11:39:00 -0800, Nathan Bossart wrote:
>> What precisely did you have in mind?  AFAICT you are asking for a wrapper
>> around write().
> 
> Partially I just want something that can easily be searched for, that can have
> comments attached to it documenting why what it is doing is safe.
> 
> It'd not be a huge amount of work to have a slow and restricted string
> interpolation support, to make it easier to write messages. Converting floats
> is probably too hard to do safely, and I'm not sure %m can safely be
> supported. But basic things like %d would be pretty simple.
> 
> Basically a loop around the format string that directly writes to stderr using
> write(), and only supports a signal safe subset of normal format strings.

Got it, thanks.  I will try to put something together along these lines,
although I don't know if I'll pick up the interpolation support in this
thread.

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com