[idleaction] Set wakeup alarm two minutes early to prevent race

If the wakeup is scheduled exactly at the time a scheduled
shutdown is, the cronjob for the shutdown would not run, as
the client is still about to wake up at that time.
If we wake up two minutes early, the cron daemon should have
enough time to fully wake up, notice the clock jump, and then
finally trigger the scheduled shutdown.

1 files changed, 8 insertions, 2 deletions

diff --git a/core/modules/idleaction/data/opt/openslx/scripts/systemd-idleaction_init b/core/modules/idleaction/data/opt/openslx/scripts/systemd-idleaction_init
index 983dfcec..ae8af404 100755
--- a/core/modules/idleaction/data/opt/openslx/scripts/systemd-idleaction_init
+++ b/core/modules/idleaction/data/opt/openslx/scripts/systemd-idleaction_init
@@ -39,8 +39,14 @@ if [ -n "$SCHEDULE" ]; then
 		[ -z "$HOUR" -o -z "$MINUTE" ] && continue
 		[ "$HOUR" -lt 0 -o "$HOUR" -gt 23 ] && continue
 		[ "$MINUTE" -lt 0 -o "$MINUTE" -gt 59 ] && continue
-		TS=$(date --date "$TODAY $t" +%s)
-		[ "$TS" -le "$NOW" ] && TS=$(date --date "$TOMORROW $t" +%s)
+		# wake up 2 minutes early; for the shutdown/reboot times this is required
+		# so the actual cronjob for the shutdown/reboot will run.
+		# Otherwise, since the wakeup will take some seconds, the actual cronjob
+		# will not trigger, since it lies a few seconds in the past.
+		# For the scheduled wakeups this would't be needed, but two minutes
+		# early shouldn't hurt anyone.
+		TS=$(date --date "-2 minutes $TODAY $t" +%s)
+		[ "$TS" -le "$NOW" ] && TS=$(date --date "-2 minutes $TOMORROW $t" +%s)
 		if [ -z "$NEXT" ] || [ "$NEXT" -gt "$TS" ]; then
 			NEXT="$TS"
 		fi