Horton

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

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-09-25T13:30:26Z
Lists: pgsql-hackers 
Michael Paquier <michael@paquier.xyz> writes:
> On Mon, Sep 24, 2018 at 01:18:47PM -0400, Tom Lane wrote:
>> Well, we have to change the code somehow to make it usable in frontend
>> as well as backend.  And we can *not* have it do exit(1) in libpq.
>> So the solution I chose was to make it act the same as if FormatMessage
>> were to fail.  I don't find this behavior unreasonable: what is really
>> important is the original error code, not whether we were able to
>> pretty-print it.  I think the ereport(FATAL) coding is a pretty darn
>> bad idea even in the backend.

> Ok.  I won't fight hard on that.  Why changing the error message from
> "could not load netmsg.dll" to "unrecognized winsock error" then?  The
> original error string is much more verbose to grab the context.

As the code stands, what you'll get told about is the error code
returned by the failed LoadLibrary call; the original winsock error
code is reported nowhere.  I think that's backwards.

We could possibly write something like

sprintf(wserrbuf, "winsock error %d (could not load netmsg.dll to translate: error code %lu)", err, GetLastError())));

but I'm unconvinced that that's useful.

			regards, tom lane

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.