#14391 [Com]: gmmktime, gmdate work incorrect

ID: 14391 Comment by: keath at keathmilligan dot net Reported By: pilots at farlep dot net Status: No Feedback Bug Type: Date/time related Operating System: Windows 2000 Server PHP Version: 4.0.6 New Comment: This is not just a Windows bug. It happens on Linux as well. It looks like gmmktime() is getting confused trying to apply some sort of daylight-savings logic. For me, gmmktime returns the correct results except for 2AM, April 6th which happens to be the start of daylight savings time in the US. The following code: $t=gmmktime(1,0,0,4,6,2003); echo "<br>inside DST: ",gmdate("Y-m-d H:i",$t); $t=gmmktime(2,0,0,4,6,2003); echo "<br>inside DST: ",gmdate("Y-m-d H:i",$t); $t=gmmktime(3,0,0,4,6,2003); echo "<br>inside DST: ",gmdate("Y-m-d H:i",$t); Yields: inside DST: 2003-04-06 01:00 inside DST: 2003-04-06 03:00 inside DST: 2003-04-06 03:00 Previous Comments: ------------------------------------------------------------------------ [2003-04-07 10:52:26] f dot vulto at re-base dot com Same problem with PEAR Date TimeZone. When converting datetimes to local timezones in Europe, PHP calculates a Daylight Savings Time (DST) starting at 2003-04-06 (= USA standard = first Sunday of April). What should've been calculated is a DST starting at 2003-03-30 (= Europe standard = last Sunday of March). I think this can be deduced to 'mktime()' or 'localtime()' not working correctly with 'TZ' environment variable on Windows: <?php $tzBackup = (getenv('TZ')) ? getenv('TZ') : ''; putenv('TZ=CET+1CEST'); print '<pre>'; $aTime = localtime(mktime(12, 0, 0, 3, 23, 2003, -1), 1); print_r($aTime); $aTime = localtime(mktime(12, 0, 0, 3, 30, 2003, -1), 1); print_r($aTime); $aTime = localtime(mktime(12, 0, 0, 4, 6, 2003, -1), 1); print_r($aTime); print '</pre>'; putenv('TZ=' . $tzBackup); ?> 'tm_isdst' should've been '1' for the second date (March 30), but is '0' on my pc. This is probably because the Microsoft '_tzset' routine doesn't know about regional DST differences. You can specify 'dzn' in 'set TZ=tzn[+|-]hh[:mm[:ss]][dzn]', but Microsoft manual says: "The C run-time library assumes the United States's rules for implementing the calculation of Daylight Saving Time (DST)" (see: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccore98/HTML/_crt__tzset.asp) which implies the exact value of 'dzn' ('CEST' in the example above) is ignored, which is what I'm experiencing. Windows seems to calculate the Daylight Saving Time with a fixed algorithm which is only true for the US but not for Europe. The result is the DST will start at wrong days. Does this mean - using Windows - you can *only* calculate the exact local time of a UTC time in a different timezone if this timezone is: 1. the local timezone of the server or 2. a timezone following US DST rules? If so, instead of TZ, PHP has to use Windows API functions and registry information to perform timezone conversions on a Windows platform. I don't have PHP core coding experience so here are some useful links :-) http://archive.devx.com/premier/mgznarch/vbpj/1999/08aug99/mt0899.pdf http://17slon.com/gp/gp/files/gptimezone.htm http://www.thedelphimagazine.com/samples/1175/1175.htm Freddy Vulto ------------------------------------------------------------------------ [2003-02-27 08:06:43] nospam at no-spam dot com The gmmktime() & windows problem still persists on 4.3.0. We now go into the third year of this bug being around. Could this become a record??? Testcase: gmmktime(0,0,0,1,1,1970); MUST return 0, also on a win box that is not in GMT-Zone. Or then, PLEASE introduce URGENTLY a new function that allows the manual correction of the TZ, e.g.: int gmmktime ( int hour, int minute, int second, int month, int day, int year [, int is_dst] [, int tz_offset]) because it boils down to the fact that the TZ-offset is the thing that is not detected correctly. ------------------------------------------------------------------------ [2003-01-12 05:41:11] frodo at interport dot net this bug has been around for over 2 years and it's a big one!!! for time based apps lets face it, the gmmktime function is extremely important. any idea when this will be fixed? ------------------------------------------------------------------------ [2003-01-08 02:13:31] napetune at hotmail dot com I use Win2K.I got this problem too. But after I updated to php 4.2.1 version, they are gone. It works well on php 4.2.1 (or higher version, I guess). Kae ------------------------------------------------------------------------ [2002-12-12 09:03:48] moonset at hotmail dot com Same problem - runing at the same time 2 systems: On Windows NT 5.0 build 2195 PHP 4.1.1 on GMT zone: echo (gmdate("U") . "<br>"); //1039704601 echo (date ("U") . "<br>"); //1039704601 echo (mktime() . "<br>"); //1039704601 echo (gmmktime() . "<br>"); //1039701001 echo (time() . "<br>"); //1039704601 On Linux webdev 2.4.19 #1 PHP 4.2.2 on EDT zone: echo (gmdate("U") . "<br>"); //1039704601 echo (date ("U") . "<br>"); //1039704601 echo (mktime() . "<br>"); //1039704601 echo (gmmktime() . "<br>"); //1039686601 echo (time() . "<br>"); //1039704601 Peter ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/14391 -- Edit this bug report at http://bugs.php.net/?id=14391&edit=1