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hwclock: fix for glibc 2.31 settimeofday() 

glibc announce:
  ... settimeofday can no longer be used to set the time and the offset
  simultaneously. If both of its two arguments are non-null, the call
  will fail (setting errno to EINVAL).

It means we need to call settimeofday(NULL, tz) and settimeofday(tv, NULL).

Unfortunately, settimeofday(NULL, tz) has very special warp-clock
semantic if used as the very first settimeofday() call. It means we
have to be sure that we do not touch warp-clock if we need only need
to modify system TZ. So, let's always call settimeofday(NULL, 0)
before settimeofday(NULL, tz) for UTC rtc mode when modify system TZ.

CC: J William Piggott <elseifthen@gmx.com>
Signed-off-by: Karel Zak <kzak@redhat.com>
Addresses: https://github.com/karelzak/util-linux/issues/957
This commit is contained in:
Karel Zak 2020-02-19 15:50:47 +01:00
parent aa506f7cc5
commit ee85d3967e
1 changed files with 28 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
sys-utils/hwclock.c
View File

@ -658,6 +658,9 @@ display_time(struct timeval hwctime)
* PCIL: persistent_clock_is_local, sets the "11 minute mode" timescale.
* firsttime: locks the warp_clock function (initialized to 1 at boot).
*
* Note that very first settimeofday(NULL, tz) modifies warp-clock as well as
* system TZ.
*
* +---------------------------------------------------------------------------+
* | op | RTC scale | settimeofday calls |
* |---------|-----------|-----------------------------------------------------|
@ -675,41 +678,45 @@ set_system_clock(const struct hwclock_control *ctl,
struct tm broken;
int minuteswest;
int rc = 0;
const struct timezone tz_utc = { 0 };
localtime_r(&newtime.tv_sec, &broken);
minuteswest = -get_gmtoff(&broken) / 60;
if (ctl->verbose) {
if (ctl->hctosys && !ctl->universal)
printf(_("Calling settimeofday(NULL, %d) to set "
"persistent_clock_is_local.\n"), minuteswest);
if (ctl->systz && ctl->universal)
if (ctl->universal)
puts(_("Calling settimeofday(NULL, 0) "
"to lock the warp function."));
"to lock the warp function."));
else
printf(_("Calling settimeofday(NULL, %d) to set "
"persistent_clock_is_local and "
"the kernel timezone.\n"), minuteswest);
if (ctl->universal && minuteswest)
printf(_("Calling settimeofday(NULL, %d) to set "
"the kernel timezone.\n"), minuteswest);
if (ctl->hctosys)
printf(_("Calling settimeofday(%ld.%06ld, %d)\n"),
newtime.tv_sec, newtime.tv_usec, minuteswest);
else {
printf(_("Calling settimeofday(NULL, %d) "), minuteswest);
if (ctl->universal)
puts(_("to set the kernel timezone."));
else
puts(_("to warp System time."));
}
printf(_("Calling settimeofday(%ld.%06ld, 0) to set "
"the kernel time.\n"), newtime.tv_sec, newtime.tv_usec);
}
if (!ctl->testing) {
const struct timezone tz_utc = { 0 };
const struct timezone tz = { minuteswest };
if (ctl->hctosys && !ctl->universal) /* set PCIL */
/* warp-clock */
if (ctl->universal)
rc = settimeofday(NULL, &tz_utc); /* lock to UTC */
else
rc = settimeofday(NULL, &tz); /* set PCIL and TZ */
/* set timezone */
if (!rc && ctl->universal && minuteswest)
rc = settimeofday(NULL, &tz);
if (ctl->systz && ctl->universal) /* lock warp_clock */
rc = settimeofday(NULL, &tz_utc);
/* set time */
if (!rc && ctl->hctosys)
rc = settimeofday(&newtime, &tz);
else if (!rc)
rc = settimeofday(NULL, &tz);
rc = settimeofday(&newtime, NULL);
if (rc) {
warn(_("settimeofday() failed"));