dnsmasq: add dhcp-script hook conditionally

Commit b32689afd6 added support for dhcp-script hook.
Adding dhcp-script config option results into two instances of dnsmasq being run
which triggered oom issues on platforms having low memory.

The dnsmasq dhcp-script config option will now only be added if at least one of the
dhcp, tftp, neigh hotplug dirs has a regular hotplug file or if the dhcpscript uci
config option is specified.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

package/network/services/dnsmasq/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=dnsmasq
 PKG_VERSION:=2.77
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=http://thekelleys.org.uk/dnsmasq/

package/network/services/dnsmasq/files/dnsmasq.init

@@ -89,6 +89,16 @@ log_once() {
 		logger -t dnsmasq "$@"
 }
 
+has_handler() {
+	local file
+
+	for file in /etc/hotplug.d/dhcp/* /etc/hotplug.d/tftp/* /etc/hotplug.d/neigh/*; do
+		[ -f "$file" ] && return 0
+	done
+
+	return 1
+}
+
 append_bool() {
 	local section="$1"
 	local option="$2"
@@ -832,8 +842,10 @@ dnsmasq_start()
 	config_get_bool readethers "$cfg" readethers
 	[ "$readethers" = "1" -a \! -e "/etc/ethers" ] && touch /etc/ethers
 
-	xappend "--dhcp-script=$DHCPSCRIPT"
 	config_get user_dhcpscript $cfg dhcpscript
+	if has_handler || [ -n "$user_dhcpscript" ]; then
+		xappend "--dhcp-script=$DHCPSCRIPT"
+	fi
 
 	config_get leasefile $cfg leasefile "/tmp/dhcp.leases"
 	[ -n "$leasefile" -a \! -e "$leasefile" ] && touch "$leasefile"