From: | Nathan Bossart <nathandbossart(at)gmail(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Fujii Masao <fujii(at)postgresql(dot)org>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: stopgap fix for signal handling during restore_command |
Date: | 2023-03-01 22:47:51 |
Message-ID: | 20230301224751.GA1823946@nathanxps13 |
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Lists: | pgsql-hackers |
On Tue, Feb 28, 2023 at 08:36:03PM -0800, Nathan Bossart wrote:
> On Sun, Feb 26, 2023 at 12:12:27PM -0800, Andres Freund wrote:
>> 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.
Here is an attempt at adding a signal safe function for writing to STDERR.
I didn't add support for format strings, but looking ahead, I think one
challenge will be avoiding va_start() and friends. In any case, IMO format
string support probably deserves its own thread.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
Attachment | Content-Type | Size |
---|---|---|
v10-0001-Move-extra-code-out-of-the-Pre-PostRestoreComman.patch | text/x-diff | 2.1 KB |
v10-0002-Don-t-proc_exit-in-startup-s-SIGTERM-handler-if-.patch | text/x-diff | 4.5 KB |
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