Date: Wed, 7 Mar 2018 10:46:24 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>,
	TipTop Labs <office@tiptop-labs.com>,
	Michael Paquier <michael.paquier@gmail.com>,
	PostgreSQL mailing lists <pgsql-bugs@postgresql.org>
Subject: Re: BUG #14999: pg_rewind corrupts control file global/pg_control
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On Tue, Mar 06, 2018 at 09:37:34PM +0100, Dmitry Dolgov wrote:
> Thank you for waiting. Yes, it also looks good for me, but I'm wondering about
> one thing - does it make sense to think about other error codes here, not only
> about `EACCESS`? E.g. if a file was removed during the process (so, it should
> be `ENOENT`), or something more exotic happened, like there are too many
> symbolic links were encountered in resolving a pathname (`ELOOP`)?

The presence of the file is ensured in the pre-phase which builds the
file map (see process_source_file), and actions are taken depending on
the presence of a file on the source and the target.  So a file missing
on the target after those pre-checks have ensured that it was actually
existing should be reported with ENOENT.  ELOOP would as well be faced
on the backend before seeing it in pg_rewind, no?  In short, it seems to
me that it is better to keep the code simple.
--
Michael

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