On Mon, Feb 08, 2016 at 10:28:58AM -0500, Jeff King wrote: > On Mon, Feb 08, 2016 at 02:33:17PM +0000, John Keeping wrote: > > > I have just noticed that with DATE_STRFTIME, the timezone in the output > > is likely to be incorrect. > > > > For all other time formats, we print the string ourselves and use the > > correct timezone from the input, but with DATE_STRFTIME strftime(3) will > > always use the system timezone. > > You mean here that the "%z" formatting will not be correct, right? > AFAICT the time shown is generally correct for the original of the > author, and we simply need to communicate the zone to strftime. > > Taking the current tip of master, for instance, I get: > > $ for i in \ > default \ > local \ > "format:%H:%M %z" \ > "format-local:%H:%M %z"; do > git log -1 --format=%ad --date="$i" ff4ea6004 > done > Fri Feb 5 15:24:02 2016 -0800 > Fri Feb 5 18:24:02 2016 > 15:24 +0000 > 18:24 +0000 > > You can see that my system is in -0500, three hours ahead of the author. > And as expected, strftime shows the time in the original author's > timezone. The %z information is totally bogus, but I don't think it has > anything to do with the system time. It is simply that we don't provide > it (...but having just looked at _your_ local timezone from your email, > I can guess how you got confused :) ). > > So I think the fix is probably just that we need to feed the zone > information to strftime via the "struct tm".
If "struct tm" had a standard field for that... Obviously "struct tm" does have a field for the offset (which is how we end up in +0000 above, because our "struct tm" comes from gmtime(3)), but it's not standardized so I don't think we can rely on it. AFAICT the only way to pass the timezone into the C library time functions is via $TZ or the global "timezone" variable, but from looking at a couple of implementations I don't think strftime() will actually look at those (the timezone is instead embedded when the "struct tm" is generated). -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
