Horton

Re: Allowing printf("%m") only where it actually works

Nico Williams <nico@cryptonector.com>

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From: Nico Williams <nico@cryptonector.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-08-19T04:50:50Z
Lists: pgsql-hackers 
On Sat, Aug 18, 2018 at 04:34:50PM -0400, Tom Lane wrote:
> So now I'm about ready to propose that we just *always* use
> snprintf.c, and forget all of the related configure probing.

Yes.

> This'd have some advantages, notably that we'd get the
> useful_strerror() behavior in frontend as well as backend,
> assuming we converted all our frontend code to use %m.

You'd also get to ensure that all uses from *die() are
async-signal-safe.

You'd also ensure that snprintf.c gets maximal testing.

> And we'd not exactly be the first project to decide that.
> But it's kind of a big move from where we are today.
> 
> Thoughts?

I think that is the best approach.

Commits

  1. In pg_log_generic(), be more paranoid about preserving errno.

  2. Make src/common/exec.c's error logging less ugly.

  3. Select appropriate PG_PRINTF_ATTRIBUTE for recent NetBSD.

  4. Fix detection of the result type of strerror_r().

  5. Try another way to detect the result type of strerror_r().

  6. Clean up *printf macros to avoid conflict with format archetypes.

  7. Fix link failures due to snprintf/strerror changes.

  8. Implement %m in src/port/snprintf.c, and teach elog.c to rely on that.

  9. Always use our own versions of *printf().

  10. Incorporate strerror_r() into src/port/snprintf.c, too.

  11. Convert elog.c's useful_strerror() into a globally-used strerror wrapper.

  12. Revert "Distinguish printf-like functions that support %m from those that don't."

  13. Produce compiler errors if errno is referenced inside elog/ereport calls.

  14. Distinguish printf-like functions that support %m from those that don't.

  15. Fix unportable usage of printf("%m").

  16. Be more robust when strerror() doesn't give a useful result.