00-check-rtc-and-wait-ntp.sh: Set the system time to th modification time of the script

The larger the difference between this system time and the NTP server time, the longer the NTP synchronization will take.
By setting the system time to the modification time of this script, which is likely to be closer to the actual time,
the NTP synchronization time can be shortened.

Signed-off-by: Norio Nomura <[email protected]>

Author: norio-nomura

pkg/cidata/cidata.TEMPLATE.d/boot/00-check-rtc-and-wait-ntp.sh

@@ -9,26 +9,55 @@ test ! -c /dev/rtc0 || exit 0
 # This script is intended for services running with systemd.
 command -v systemctl >/dev/null 2>&1 || exit 0
 
+echo_with_time_usec() {
+	time_usec=$(timedatectl show --property=TimeUSec)
+	echo "${time_usec}, ${1}"
+}
+
 # Enable `systemd-time-wait-sync.service` to wait for NTP synchronization at an earlier stage.
 systemctl enable systemd-time-wait-sync.service
 
 # For the first boot, where the above setting is not yet active, wait for NTP synchronization here.
 max_retry=60 retry=0
 until ntp_synchronized=$(timedatectl show --property=NTPSynchronized --value) && [ "${ntp_synchronized}" = "yes" ] ||
 	[ "${retry}" -gt "${max_retry}" ]; do
-	time_usec=$(timedatectl show --property=TimeUSec)
-	echo "${time_usec}, Waiting for NTP synchronization..."
+	if [ "${retry}" -eq 0 ]; then
+		# If /dev/rtc is not available, the system time set during the Linux kernel build is used.
+		# The larger the difference between this system time and the NTP server time, the longer the NTP synchronization will take.
+		# By setting the system time to the modification time of this script, which is likely to be closer to the actual time,
+		# the NTP synchronization time can be shortened.
+		echo_with_time_usec "Setting the system time to the modification time of ${0}."
+
+		# To set the time to a specified time, it is necessary to stop systemd-timesyncd.
+		systemctl stop systemd-timesyncd
+
+		# Since `timedatectl set-time` fails if systemd-timesyncd is not stopped,
+		# ensure that it is completely stopped before proceeding.
+		until pid_of_timesyncd=$(systemctl show systemd-timesyncd --property=MainPID --value) && [ "${pid_of_timesyncd}" -eq 0 ]; do
+			echo_with_time_usec "Waiting for systemd-timesyncd to stop..."
+			sleep 1
+		done
+
+		# Set the system time to the modification time of this script.
+		modification_time=$(stat -c %y "${0}")
+		echo_with_time_usec "Setting the system time to ${modification_time}."
+		timedatectl set-time "${modification_time}"
+
+		# Restart systemd-timesyncd
+		systemctl start systemd-timesyncd
+	else
+		echo_with_time_usec "Waiting for NTP synchronization..."
+	fi
 	retry=$((retry + 1))
 	sleep 1
 done
 # Print the result of NTP synchronization
 ntp_message=$(timedatectl show-timesync --property=NTPMessage)
-time_usec=$(timedatectl show --property=TimeUSec)
 if [ "${ntp_synchronized}" = "yes" ]; then
-	echo "${time_usec}, NTP synchronization complete."
+	echo_with_time_usec "NTP synchronization complete."
 	echo "${ntp_message}"
 else
-	echo "${time_usec}, NTP synchronization timed out."
+	echo_with_time_usec "NTP synchronization timed out."
 	echo "${ntp_message}"
 	exit 1
 fi