travelmate: fix possible race condition

* prevent possible duplicate script execution due to
  multiple ntp events in parallel

Signed-off-by: Dirk Brenken <dev@brenken.org>

net/travelmate/Makefile

@@ -7,7 +7,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=travelmate
 PKG_VERSION:=2.0.2
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 PKG_LICENSE:=GPL-3.0-or-later
 PKG_MAINTAINER:=Dirk Brenken <dev@brenken.org>
 

net/travelmate/files/travelmate_ntp.hotplug

@@ -22,10 +22,14 @@ f_log()
 	fi
 }
 
-if [ "${ACTION}" = "stratum" ] && [ ! -f "${trm_ntpfile}" ] && \
-	[ "$("${trm_init}" enabled; printf "%u" ${?})" = "0" ]
+if [ "${ACTION}" = "stratum" ] && [ ! -f "${trm_ntpfile}" ] && [ "$("${trm_init}" enabled; printf "%u" ${?})" = "0" ]
 then
-	> "${trm_ntpfile}"
-	f_log "info" "get ntp time sync"
-	"${trm_init}" restart
+	{
+		flock -xn 1001
+		if [ "$?" = "0" ]
+		then
+			f_log "info" "get ntp time sync"
+			"${trm_init}" restart
+		fi
+	} 1001>"${trm_ntpfile}"
 fi