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hwclock: don't warp the systemtime if the RTC is in UTC 

A sideeffect of 839be2ba6b is that we now
warp the systemtime according to the timezone, on the first call of
--systz. This is not always the correct thing to do, and causes a
regression for us in Arch Linux.

The behavior is correct if the RTC, and hence the systemtime, is
in localtime. However, if the systemtime is already in UTC we don't
want to touch it when we set the kernel timezone (which we still need to
do as some filesystems use this information).

An almost identical issue was also fixed in systemd commit
72edcff5db936e54cfc322d9392ec46e2428fd9b.

Signed-off-by: Tom Gundersen <teg@jklm.no>
This commit is contained in:
Tom Gundersen 2012-09-20 22:02:46 +00:00 committed by Karel Zak
parent 72fc8ca062
commit 910a090039
2 changed files with 22 additions and 6 deletions
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11
sys-utils/hwclock.8
View File

@ -58,10 +58,12 @@ This is a good option to use in one of the system startup scripts.
Set the Hardware Clock to the current System Time.
.TP
.B \-\-systz
Reset the System Time based on the current timezone.
Set the kernel's timezone and reset the System Time based on the current timezone.
Also set the kernel's timezone value to the local timezone
as indicated by the TZ environment variable and/or
The system time is only reset on the first call after boot.
The local timezone is taken to be what is
indicated by the TZ environment variable and/or
.IR /usr/share/zoneinfo ,
as
.BR tzset (3)
@ -74,7 +76,8 @@ This is an alternate option to
.B \-\-hctosys
that does not read the hardware clock, and may be used in system startup
scripts for recent 2.6 kernels where you know the System Time contains
the Hardware Clock time.
the Hardware Clock time. If the Hardware Clock is already in UTC, it is
not reset.
.TP
.B \-\-adjust
Add or subtract time from the Hardware Clock to account for systematic

17
sys-utils/hwclock.c
View File

@ -772,7 +772,6 @@ static int set_system_clock_timezone(const bool universal, const bool testing)
struct timeval tv;
struct tm *broken;
int minuteswest;
int rc;
gettimeofday(&tv, NULL);
if (debug) {
@ -818,10 +817,24 @@ static int set_system_clock_timezone(const bool universal, const bool testing)
("Not setting system clock because running in test mode.\n"));
retcode = 0;
} else {
const struct timezone tz_utc = { 0, 0 };
const struct timezone tz = { minuteswest, 0 };
const struct timeval *tv_null = NULL;
int rc = 0;
/* The first call to settimeofday after boot will assume the systemtime
* is in localtime, and adjust it according to the given timezone to
* compensate. If the systemtime is in fact in UTC, then this is wrong
* so we first do a dummy call to make sure the time is not shifted.
*/
if (universal)
rc = settimeofday(tv_null, &tz_utc);
/* Now we set the real timezone. Due to the above dummy call, this will
* only warp the systemtime if the RTC is not in UTC. */
if (!rc)
rc = settimeofday(tv_null, &tz);
rc = settimeofday(tv_null, &tz);
if (rc) {
if (errno == EPERM) {
warnx(_