Only allow --update-drift for --set or --systohc
Signed-off-by: J William Piggott <elseifthen@xxxxxxx>
---
sys-utils/hwclock.8.in | 3 +--
sys-utils/hwclock.c | 7 ++++++-
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/sys-utils/hwclock.8.in b/sys-utils/hwclock.8.in
index cf33e63..72b842e 100644
--- a/sys-utils/hwclock.8.in
+++ b/sys-utils/hwclock.8.in
@@ -376,9 +376,8 @@ in learning about the internal operations of hwclock.
.B \-\-update\-drift
Update the Hardware Clock's drift factor in
.IR @ADJTIME_PATH@ .
-It is used with
+It can only be used with
.BR \-\-set " or " \%\-\-systohc ,
-otherwise it is ignored.
.sp
A minimum four hour period between settings is required. This is to
avoid invalid calculations. The longer the period, the more precise the
diff --git a/sys-utils/hwclock.c b/sys-utils/hwclock.c
index 5868ad6..7d69b7a 100644
--- a/sys-utils/hwclock.c
+++ b/sys-utils/hwclock.c
@@ -1233,7 +1233,7 @@ usage(const struct hwclock_control *ctl, FILE *out)
#if defined(__linux__) && defined(__alpha__)
fputs(_(" --epoch <year> epoch input for --setepoch\n"), out);
#endif
- fputs(_(" --update-drift update drift factor (requires --set or --systohc)\n"), out);
+ fputs(_(" --update-drift update the RTC drift factor\n"), out);
fprintf(out, _(
" --noadjfile do not use %1$s\n"
" --adjfile <file> use an alternate file to %1$s\n"), _PATH_ADJTIME);
@@ -1465,6 +1465,11 @@ int main(int argc, char **argv)
if (!ctl.adj_file_name)
ctl.adj_file_name = _PATH_ADJTIME;
+ if (ctl.update && !ctl.set && !ctl.systohc) {
+ warnx(_("--update-drift requires --set or --systohc"));
+ hwclock_exit(&ctl, EX_USAGE);
+ }
+
if (ctl.noadjfile && !ctl.utc && !ctl.local_opt) {
warnx(_("With --noadjfile, you must specify "
"either --utc or --localtime"));
--
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