Horton

Re: Thread-unsafe coding in ecpg

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Meskes <meskes@postgresql.org>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2019-01-20T00:37:29Z
Lists: pgsql-hackers 
Michael Meskes <meskes@postgresql.org> writes:
>> While (b) has more theoretical purity, I'm inclined to think it
>> doesn't really improve anybody's life compared to (a), because
>> --disable-thread-safety doesn't actually stop anyone from using
>> libpq or ecpglib in threaded environments.  It just makes it
>> more likely to fail when they do.

> The question is, what do we do on those platforms? Use setlocale() or
> fallback to (a) and document that ecpg has to run in a C locale?

No, we shouldn't use setlocale(), because it clearly is hazardous
even on platforms where it doesn't fail outright.  I don't see
anything so wrong with just documenting the hazard.  The situation
isn't noticeably more dangerous than simple use of the C library;
sscanf, strtod, etc are all likely to do surprising things when
LC_NUMERIC isn't C.

> We could also rewrite the parsing of numbers to not be locale
> dependent.

Perhaps, but that seems like a giant undertaking.  I'm not excited
about duplicating strtod(), for instance.

			regards, tom lane

Commits

  1. Remove _configthreadlocale() calls in ecpg test suite.

  2. Remove infinite-loop hazards in ecpg test suite.

  3. Blind attempt to fix _configthreadlocale() failures on MinGW.

  4. Avoid thread-safety problem in ecpglib.

  5. Second try at fixing ecpglib thread-safety problem.