Re: [libvirt] [PATCHv2] util: fix virTimeLocalOffsetFromUTC DST processing

The original version of virTimeLocalOffsetFromUTC() would fail for certain times of the day if daylight savings time was active. This could most easily be seen by uncommenting the TEST_LOCALOFFSET() cases that include a DST setting.

src/util/virtime.c | 3 +++ tests/virtimetest.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++------- 2 files changed, 56 insertions(+), 8 deletions(-) diff --git a/src/util/virtime.c b/src/util/virtime.c index 3a56400..c69dff1 100644 --- a/src/util/virtime.c +++ b/src/util/virtime.c @@ -377,6 +377,9 @@ virTimeLocalOffsetFromUTC(long *offset) return -1; } + /* tell mktime to figure out itself whether or not DST is in effect */ + gmtimeinfo.tm_isdst = -1;

+ +/* return true if the date is Jan 1 or Dec 31 (localtime) */ +static bool +IsJan1OrDec31(void)

+ + if (!IsJan1OrDec31()) { + /* experiments have shown that the following tests will fail + * during certain hours of Dec 31 or Jan 1 (depending on the + * TZ setting in the shell running the test, but in general + * for a period that apparently starts at 00:00:00 UTC Jan 1 + * and continues for 1 - 2 hours). We've determined this is + * due to our inability to specify a timezone with DST on/off + * settings that make it truly *always* on DST - i.e. it is a + * failing of the test data, *not* of the function we are + * testing. So to test as much as possible, we still run these + * tests, except on Dec 31 and Jan 1.