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| author | Joseph Parmelee | 2013-03-18 05:48:57 +0100 |
|---|---|---|
| committer | Karel Zak | 2013-03-18 10:31:32 +0100 |
| commit | d53f8ecfbf036eddb2aef737dc0973a613d80ced (patch) | |
| tree | 8530b3f24f23de976a01fbaec92e2693f2fbcebe /sys-utils/hwclock.c | |
| parent | fsck.cramfs: fix compiler warnings (diff) | |
| download | kernel-qcow2-util-linux-d53f8ecfbf036eddb2aef737dc0973a613d80ced.tar.gz kernel-qcow2-util-linux-d53f8ecfbf036eddb2aef737dc0973a613d80ced.tar.xz kernel-qcow2-util-linux-d53f8ecfbf036eddb2aef737dc0973a613d80ced.zip | |
hwclock: make hwclock leap-second-aware
Attached is a patch file leap_seconds.patch against util-linux-2.22.2
that allows leap seconds to be included in hwclock --show or --hctosys.
The current code uses the default UTC zonefile in reading the hardware
RTC with mktime(). This zonefile usually does not include leap
seconds. As of this date there have been a total of 25 leap seconds
added since the epoch (start of 1970). This is particularly a problem
for systems using ntp to maintain their system clocks because ntp does
take leap seconds into account. A user can specify a leap-second-aware
zonefile via /etc/localtime. By defining the environment variable
TZUTC, mktime() can be induced to use a matching UTC zonefile that
includes leap seconds. The default behavior (TZUTC undefined) is
unchanged.
Regards,
Joseph Parmelee
jparmele at wildbear.com
Diffstat (limited to 'sys-utils/hwclock.c')
| -rw-r--r-- | sys-utils/hwclock.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/sys-utils/hwclock.c b/sys-utils/hwclock.c index 9256ec5bd..b7f569207 100644 --- a/sys-utils/hwclock.c +++ b/sys-utils/hwclock.c @@ -382,8 +382,15 @@ mktime_tz(struct tm tm, const bool universal, */ zone = getenv("TZ"); /* remember original time zone */ if (universal) { - /* Set timezone to UTC */ - setenv("TZ", "", TRUE); + /* Set timezone to UTC as defined by the environment + * variable TZUTC. TZUTC undefined gives the default UTC + * zonefile which usually does not take into account leap + * seconds. Define TZUTC to select your UTC zonefile which + * does include leap seconds. For example, with recent GNU + * libc's: + * TZUTC=:/usr/share/zoneinfo/right/UTC + */ + setenv("TZ", getenv("TZUTC"), TRUE); /* * Note: tzset() gets called implicitly by the time code, * but only the first time. When changing the environment |