Re: [libvirt] [PATCHv2 1/4] util: new function virTimeLocalOffsetFromUTC

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!