update example ntp.script

Handle an interesting corner case when NTP server is reachable...
but on a different IP now.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 19 insertions, 2 deletions

diff --git a/examples/var_service/ntpd/ntp.script b/examples/var_service/ntpd/ntp.script
index 76c34bf74..8542181eb 100755
--- a/examples/var_service/ntpd/ntp.script
+++ b/examples/var_service/ntpd/ntp.script
@@ -10,12 +10,30 @@
 
 dt=`date '+%Y-%m-%d %H:%M:%S'`
 
+echo "`tail -n 199 -- "$0.log" 2>/dev/null`" >"$0.log.$$"
+
+if test x"$1" = x"unsync" \
+; then
+        # No replies for our NTP requests were seen for some time.
+        #
+        # Among more mundate cases like network outages, this happens
+        # if we ran for a LONG time (days) and ntp server's IP has changed.
+        # ntpd has no code to re-resolve peers' addresses to IPs,
+        # we need to help it:
+        #
+        echo "$dt: $1"\
+                "syncronization lost, restarting ntpd"\
+                >>"$0.log.$$"
+        mv -- "$0.log.$$" "$0.log"
+        kill $PPID
+        exit
+fi
+
 if test x"$stratum" != x"" \
 && test x"$poll_interval" != x"" \
 && test 4 -ge "$stratum" \
 && test 128 -le "$poll_interval" \
 ; then
-        echo "`tail -n 199 -- "$0.log" 2>/dev/null`" >"$0.log.$$"
         echo "$dt: $1"\
                 "freq_drift_ppm=$freq_drift_ppm"\
                 "offset=$offset"\
@@ -27,7 +45,6 @@ if test x"$stratum" != x"" \
         exec hwclock --systohc
 fi
 
-echo "`tail -n 199 -- "$0.log" 2>/dev/null`" >"$0.log.$$"
 echo "$dt: $1"\
         "freq_drift_ppm=$freq_drift_ppm"\
         "offset=$offset"\