Implement new option --predict-hc that predicts what the RTC will read
at a time given by the --date option. This is useful for example if
you need to setup an RTC wakeup time to distant future and want to
account for the RTC drift.
Signed-off-by: Timo Juhani Lindfors <timo.lindfors@xxxxxx>
---
hwclock/hwclock.8 | 7 +++++++
hwclock/hwclock.c | 41 ++++++++++++++++++++++++++++++-----------
2 files changed, 37 insertions(+), 11 deletions(-)
diff --git a/hwclock/hwclock.8 b/hwclock/hwclock.8
index 55663fe..7b2df6c 100644
--- a/hwclock/hwclock.8
+++ b/hwclock/hwclock.8
@@ -132,6 +132,13 @@ For example, on a Digital Unix machine:
.sp
.I hwclock --setepoch --epoch=1952
+.TP
+.BI \-\-predict\-hc
+Predict what the RTC will read at time given by the
+.B \-\-date
+option based on the adjtime file. This is useful for example if you
+need to set an RTC wakeup time to distant future and want to account
+for the RTC drift.
.SH OPTIONS
.PP
diff --git a/hwclock/hwclock.c b/hwclock/hwclock.c
index c07f757..8316678 100644
--- a/hwclock/hwclock.c
+++ b/hwclock/hwclock.c
@@ -1124,7 +1124,7 @@ manipulate_clock(const bool show, const bool adjust, const bool noadjfile,
const bool hctosys, const bool systohc, const bool systz,
const struct timeval startup_time,
const bool utc, const bool local_opt,
- const bool testing) {
+ const bool testing, const bool predict_hc) {
/*---------------------------------------------------------------------------
Do all the normal work of hwclock - read, set clock, etc.
@@ -1137,13 +1137,13 @@ manipulate_clock(const bool show, const bool adjust, const bool noadjfile,
int rc; /* local return code */
bool no_auth; /* User lacks necessary authorization to access the clock */
- if (!systz) {
+ if (!systz && !predict_hc) {
no_auth = ur->get_permissions();
if (no_auth)
return EX_NOPERM;
}
- if (!noadjfile && (adjust || set || systohc || (!utc && !local_opt))) {
+ if (!noadjfile && (adjust || set || systohc || (!utc && !local_opt) || predict_hc)) {
rc = read_adjtime(&adjtime);
if (rc)
return rc;
@@ -1177,7 +1177,7 @@ manipulate_clock(const bool show, const bool adjust, const bool noadjfile,
Defined only if hclock_valid is true.
*/
- if (show || adjust || hctosys || (!noadjfile && !systz)) {
+ if (show || adjust || hctosys || (!noadjfile && !systz && !predict_hc)) {
/* data from HW-clock are required */
rc = synchronize_to_clock_tick();
if (rc && rc != 2) /* 2= synchronization timeout */
@@ -1227,6 +1227,20 @@ manipulate_clock(const bool show, const bool adjust, const bool noadjfile,
printf(_("Unable to set system clock.\n"));
return rc;
}
+ } else if (predict_hc) {
+ int adjustment;
+ double retro;
+
+ calculate_adjustment(adjtime.drift_factor,
+ adjtime.last_adj_time,
+ adjtime.not_adjusted,
+ set_time,
+ &adjustment, &retro);
+ if (debug) {
+ printf(_("At %ld seconds after 1969, RTC is predicted to read %ld seconds after 1969.\n"),
+ set_time, set_time + adjustment);
+ }
+ display_time(TRUE, set_time + adjustment, -retro);
}
if (!noadjfile)
save_adjtime(adjtime, testing);
@@ -1322,6 +1336,7 @@ usage( const char *fmt, ... ) {
" --getepoch print out the kernel's hardware clock epoch value\n"
" --setepoch set the kernel's hardware clock epoch value to the \n"
" value given with --epoch\n"
+ " --predict-hc predict rtc reading at time given with --date\n"
" -v | --version print out the version of hwclock to stdout\n"
"\nOptions: \n"
" -u | --utc the hardware clock is kept in UTC\n"
@@ -1391,6 +1406,7 @@ static const struct option longopts[] = {
{ "rtc", 1, 0, 'f' },
{ "adjfile", 1, 0, 138 },
{ "systz", 0, 0, 139 },
+ { "predict-hc", 0, 0, 140 },
{ NULL, 0, 0, 0 }
};
@@ -1416,7 +1432,7 @@ main(int argc, char **argv) {
/* Variables set by various options; show may also be set later */
/* The options debug, badyear and epoch_option are global */
- bool show, set, systohc, hctosys, systz, adjust, getepoch, setepoch;
+ bool show, set, systohc, hctosys, systz, adjust, getepoch, setepoch, predict_hc;
bool utc, testing, local_opt, noadjfile, directisa;
bool ARCconsole, Jensen, SRM, funky_toy;
char *date_opt;
@@ -1446,7 +1462,7 @@ main(int argc, char **argv) {
textdomain(PACKAGE);
/* Set option defaults */
- show = set = systohc = hctosys = systz = adjust = noadjfile = FALSE;
+ show = set = systohc = hctosys = systz = adjust = noadjfile = predict_hc = FALSE;
getepoch = setepoch = utc = local_opt = testing = debug = FALSE;
ARCconsole = Jensen = SRM = funky_toy = directisa = badyear = FALSE;
date_opt = NULL;
@@ -1522,6 +1538,9 @@ main(int argc, char **argv) {
case 139:
systz = TRUE; /* --systz */
break;
+ case 140:
+ predict_hc = TRUE; /* --predict-hc */
+ break;
case 'f':
rtc_dev_name = optarg; /* --rtc */
break;
@@ -1554,7 +1573,7 @@ main(int argc, char **argv) {
}
if (show + set + systohc + hctosys + systz + adjust + getepoch
- + setepoch > 1){
+ + setepoch + predict_hc > 1){
fprintf(stderr, _("You have specified multiple functions.\n"
"You can only perform one function "
"at a time.\n"));
@@ -1595,7 +1614,7 @@ main(int argc, char **argv) {
set_cmos_access(Jensen, funky_toy);
#endif
- if (set) {
+ if (set || predict_hc) {
rc = interpret_date_string(date_opt, &set_time);
/* (time-consuming) */
if (rc != 0) {
@@ -1606,7 +1625,7 @@ main(int argc, char **argv) {
}
if (!(show | set | systohc | hctosys | systz | adjust | getepoch
- | setepoch))
+ | setepoch | predict_hc))
show = 1; /* default to show */
@@ -1643,7 +1662,7 @@ main(int argc, char **argv) {
if (debug)
out_version();
- if (!systz) {
+ if (!systz && !predict_hc) {
determine_clock_access_method(directisa);
if (!ur) {
fprintf(stderr,
@@ -1660,7 +1679,7 @@ main(int argc, char **argv) {
rc = manipulate_clock(show, adjust, noadjfile, set, set_time,
hctosys, systohc, systz, startup_time, utc,
- local_opt, testing);
+ local_opt, testing, predict_hc);
hwclock_exit(rc);
return rc; /* Not reached */
}
--
1.7.0
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