Re: Server crash with older tzload library

Even we were fail to re-produce it always. It is crashing randomly. After debugging, we found following values in tzstate variable when it crashed. So I manually modified it at the beginning of pg_tzset() function.

/* Initialize tzstate with some arbitrary values */
tzstate.goback = 277946440;
tzstate.goahead = 0;
tzstate.ats[0] = 8892;

Also not that, tzstate variable remains uninitialized properly when tzload() call returns -1. To mimic this, I have just renamed posixrules timezone file to something else. So that tzload returns -1. And as tzload can return -1 in any failure case and as we don't have that check at callee side tzstate variable remains uninitialized which leading to a server crash. As above garbage values too leads to a crash.

In summary, following are the steps to re-produce:
 - Add above three lines at the beginning of the pg_tzset() function
 - make install
 - mv install/share/postgresql/timezone/posixrules install/share/postgresql/timezoneposixrules_a  (or remove it)
 - start the server
 - run these two statements on psql prompt
   + SET TimeZone = 'GMT+3:30';
   + SELECT '1969-12-31 20:30:00'::timestamptz;

BTW, after your commit, tzload() function now sets goback and goahead variable to FALSE which fixes the server crash. MemSet in 2010c is just doing it explicitly before calling tzload though.

Thanks for committing the part of the patch which stopped crashing the server with above mentioned steps.

Thanks