On Fri, May 23, 2014 at 02:43:08PM +0300, Laine Stump wrote: > On 05/22/2014 09:49 PM, Marcelo Tosatti wrote: > > On Thu, May 22, 2014 at 02:07:27PM +0300, Laine Stump wrote: > >> Since there isn't a single libc API to get this value, this patch > >> supplies one which gets the value by grabbing current UTC, then > >> converting that into a struct tm with localtime_r(), then back to a > >> time_t using mktime; it again does the same operation, but using > >> gmtime_r() instead (for UTC). It then subtracts utc time from the > >> localtime, and finally adjusts if dst is set in the localtime timeinfo > >> (because for some reason mktime doesn't take that into account). > >> > >> This function should be POSIX-compliant, and is threadsafe, but not > >> async signal safe. If it was ever necessary to know this value in a > >> child process, we could cache it with a one-time init function when > >> libvirtd starts, then just supply the cached value, but that > >> complexity isn't needed for current usage. > >> --- > >> > >> Change from V1: add test cases with TZ set to different values (if > >> someone knows how to force DST on/off, I would gladly add some test > >> cases for this as well). > > > > man tzset: > > > > The second format is used when there is daylight saving time: > > > > std offset dst [offset],start[/time],end[/time] > > Aha! And combining that with the "VIR" timezone idea that we're already > using, I've found that the following string *does* set DST: > > TZ="VIR02:30VID,0,365" > > while the following *doesn't* (at least not today :-): > > TZ="VIR02:30VID,300,365" > > So I can add the former as a test case. > > Thanks! Btw TZ also contains != 1hour daylight offset information (see that section of man tzset). I'll send a QEMU patch to add a command to query the RTC offset. -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list