Bug #42645 [Com]: getdate/mktime does not always add/subtract dst offset

Edit report at https://bugs.php.net/bug.php?id=42645&edit=1 ID: 42645 Comment by: carstenklein at yahoo dot de Reported by: carstenklein at yahoo dot de Summary: getdate/mktime does not always add/subtract dst offset Status: Not a bug Type: Bug Package: Date/time related Operating System: Linux Ubuntu PHP Version: 5.2.4 Block user comment: N Private report: N New Comment: One more thing, though 1981-03-29 02:30:00 is a very valid date and time. Not so much 1981-02-29 02:30:00 which I believe you had in mind. Previous Comments: ------------------------------------------------------------------------ [2015-04-08 21:14:40] carstenklein at yahoo dot de *) what is marked as FAILURE is actually correct, however, all the other dates before also transition from non-dst to dst, in the local configuration, i.e. CET to CEST, so these should also have a local time reading of 03:30:30 instead of just 02:30:30. considering the above, overall dst behaviour of getdate() seems to be off. and besides of that, if you feel happy with your current solution, go on with it as I have moved pass PHP and am no longer using it. ------------------------------------------------------------------------ [2015-04-08 21:10:04] carstenklein at yahoo dot de Or rather not so much random as sunday is considered the first day of the week in some regions of the world. Perhaps in getdate() there is some special cased dst adjustment logic that needs to be eliminated? ------------------------------------------------------------------------ [2015-04-08 21:05:22] carstenklein at yahoo dot de It seems as if you are missing the actual point here. Actual: 1981-03-29 03:30:00 + 3 days = 1981-04-01 03:30:00 <--- ERR See the actual, it already has the timezone offset added to it. Naturally, the calculated datetime will have it, too. So the actual problem lies within $t = getdate( $date ) which will already apply the dst offset on a rather random basis. As such I would consider this a standing bug rather than a NAB. ------------------------------------------------------------------------ [2015-04-08 20:46:25] requinix@php.net Alright. Then after almost 8 years of this bug being around, I'm going to close this as NAB. Here's why: The most important thing is that 1981-03-29 02:30:00 is not a valid time (in that timezone). It does not exist. See how the code tries to use 2:30 for the start time but the actual printout says 3:30? The most reasonable interpretation of 2:30 is "2 hours 30 minutes after midnight", but because of daylight savings and the jump from 1:59:59 to 3:00:00, that time turns out to be 3:30 AM. If you add whatever day interval to that then you're still going to get 3:30 AM because (1) it didn't start at 2:30 and (2) all "+N days" does is add N to the day number, then potentially adjust for wrapping out-of-bounds numbers and such (eg, 3/29 +3 days = 3/32, which wraps to 4/1). So you can't actually start with a datetime of 1981-03-29 02:MM:SS. You can, however, simulate that by using mktime() *and adding your day interval at the same time*. As in mktime(2, 30, 0, 3, 29 + 3, 1981) // adding the day at this point http://3v4l.org/8ob1c By doing that you bypass the "invalid time" problem but still make use of the "adjust for wrapping" feature. It also more closely reflects the logical process of "take this date and add 3 days to it" that a human would follow. ------------------------------------------------------------------------ [2015-04-08 14:17:26] carstenklein at yahoo dot de Yes, it does reproduce the issue, the error occurs with older PHP versions I believe. Timezone: Europe/Amsterdam Expected: 1981-03-28 02:30:00 + 3 days = 1981-03-31 02:30:00 Actual: 1981-03-28 02:30:00 + 3 days = 1981-03-31 02:30:00 Expected: 1981-03-29 02:30:00 + 3 days = 1981-04-01 02:30:00 Actual: 1981-03-29 03:30:00 + 3 days = 1981-04-01 03:30:00 <--- ERR Expected: 1981-03-30 02:30:00 + 3 days = 1981-04-02 02:30:00 Actual: 1981-03-30 02:30:00 + 3 days = 1981-04-02 02:30:00 ------------------------------------------------------------------------ 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 https://bugs.php.net/bug.php?id=42645 -- Edit this bug report at https://bugs.php.net/bug.php?id=42645&edit=1