Horton

Safeguards against incorrect fd flags for fsync()

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-10-09T06:26:40Z
Lists: pgsql-hackers

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Hi all,

After the set of issues discussed here, it seems to me that it would
be a good thing to have some safeguards against incorrect flags when
opening a fd which would be used for fsync():
https://www.postgresql.org/message-id/16039-196fc97cc05e141c@postgresql.org

Attached is a patch aimed at doing that.  Historically O_RDONLY is 0,
so when looking at a directory we just need to make sure that no write
flags are used.  For files, that's the contrary, a write flag has to
be used.

Thoughts or better ideas?

Thanks,
--
Michael

Commits

  1. Make safeguard against incorrect flags for fsync more portable.

  2. Add safeguards for pg_fsync() called with incorrectly-opened fds