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rtc: restore time from driftfile if later than RTC time

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This is useful on computers that have an RTC, but there is no battery to
keep the time when they are turned off and start with the same time on
each boot.
This commit is contained in:
Miroslav Lichvar
2015-10-06 15:52:36 +02:00
parent 1714d3e8ae
commit 6a9c756cf0
5 changed files with 53 additions and 44 deletions
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50
rtc.c
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@@ -44,7 +44,7 @@ static int driver_preinit_ok = 0;
static struct {
int (*init)(void);
void (*fini)(void);
int (*time_pre_init)(void);
int (*time_pre_init)(time_t driftfile_time);
void (*time_init)(void (*after_hook)(void*), void *anything);
void (*start_measurements)(void);
int (*write_parameters)(void);
@@ -74,29 +74,37 @@ static struct {
};
/* ================================================== */
/* Set the system clock to the time of last modification of driftfile
if it's in the future */
/* Get the last modification time of the driftfile */
static void
fallback_time_init(void)
static time_t
get_driftfile_time(void)
{
struct timeval now;
struct stat buf;
char *drift_file;
drift_file = CNF_GetDriftFile();
if (!drift_file)
return;
return 0;
if (stat(drift_file, &buf))
return;
return 0;
return buf.st_mtime;
}
/* ================================================== */
/* Set the system time to the driftfile time if it's in the future */
static void
apply_driftfile_time(time_t t)
{
struct timeval now;
LCL_ReadCookedTime(&now, NULL);
if (now.tv_sec < buf.st_mtime) {
if (LCL_ApplyStepOffset(now.tv_sec - buf.st_mtime))
LOG(LOGS_INFO, LOGF_Rtc, "System clock set from driftfile %s",
drift_file);
if (now.tv_sec < t) {
if (LCL_ApplyStepOffset(now.tv_sec - t))
LOG(LOGS_INFO, LOGF_Rtc, "System time restored from driftfile");
}
}
@@ -105,18 +113,24 @@ fallback_time_init(void)
void
RTC_Initialise(int initial_set)
{
time_t driftfile_time;
char *file_name;
/* Do an initial read of the RTC and set the system time to it. This
is analogous to what /sbin/hwclock -s would do on Linux. If that fails
or RTC is not supported, set the clock to the time of the last
modification of driftfile, so we at least get closer to the truth. */
/* If the -s option was specified, try to do an initial read of the RTC and
set the system time to it. Also, read the last modification time of the
driftfile (i.e. system time when chronyd was previously stopped) and set
the system time to it if it's in the future to bring the clock closer to
the true time when the RTC is broken (e.g. it has no battery), is missing,
or there is no RTC driver. */
if (initial_set) {
if (driver.time_pre_init && driver.time_pre_init()) {
driftfile_time = get_driftfile_time();
if (driver.time_pre_init && driver.time_pre_init(driftfile_time)) {
driver_preinit_ok = 1;
} else {
driver_preinit_ok = 0;
fallback_time_init();
if (driftfile_time)
apply_driftfile_time(driftfile_time);
}
}