Horton

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

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>, Thomas Munro <thomas.munro@enterprisedb.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-09-25T15:48:29Z
Lists: pgsql-hackers 
On 2018-Sep-25, Tom Lane wrote:

> Michael Paquier <michael@paquier.xyz> writes:

> > 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.

I agree that the winsock problem is the main one we should be reporting,
including its numeric error code.  Even if we can't translate it, the
numeric value can be translated by web-searching, if it comes to that.

> 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.

Actually I think it *is* useful to do it like this, because then the
user knows to fix the netmsg.dll problem so that they can continue to
investigate the winsock problem.  If we don't report the secondary error
message, how are users going to figure out how to fix the problem?

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.