[source] lldpd: fix reload function for when interfaces change

[LEDE Commits]

jow pushed a commit to source.git, branch master:
https://git.lede-project.org/909f0630663d7ae1471c76154516e3299992a150

commit 909f0630663d7ae1471c76154516e3299992a150
Author: Alexandru Ardelean <ardeleanalex at gmail.com>
AuthorDate: Wed Oct 21 16:11:09 2015 +0300

    lldpd: fix reload function for when interfaces change
    
    The problem is that interfaces are specified at start as
    command line arguments, making them unchange-able via reload.
    
    That means, we have to move (since lldpd allows this) the
    interfaces-match-pattern option to be in a config file and reload
    the configuration.
    It's either that, or do a 'restart'.
    
    Since we're generating the lldpd.conf file, we'll have to
    move the 'sysconfdir' of lldpd to /tmp, where the files will
    get written ; this will prevent any unncessary flash writes.
    
    Signed-off-by: Alexandru Ardelean <ardeleanalex at gmail.com>
---
 package/network/services/lldpd/Makefile         |  1 +
 package/network/services/lldpd/files/lldpd.init | 63 +++++++++++++++++--------
 2 files changed, 44 insertions(+), 20 deletions(-)

diff --git a/package/network/services/lldpd/Makefile b/package/network/services/lldpd/Makefile
index b2b1f38..ff15057 100644
--- a/package/network/services/lldpd/Makefile
+++ b/package/network/services/lldpd/Makefile
@@ -94,6 +94,7 @@ CONFIGURE_ARGS += \
 	--with-embedded-libevent=no \
 	--disable-hardening \
 	--without-xml \
+	--sysconfdir=/tmp \
 	$(if $(CONFIG_LLDPD_WITH_CDP),,--disable-cdp) \
 	$(if $(CONFIG_LLDPD_WITH_FDP),,--disable-fdp) \
 	$(if $(CONFIG_LLDPD_WITH_EDP),,--disable-edp) \
diff --git a/package/network/services/lldpd/files/lldpd.init b/package/network/services/lldpd/files/lldpd.init
index 16a6db3..8fe0a47 100644
--- a/package/network/services/lldpd/files/lldpd.init
+++ b/package/network/services/lldpd/files/lldpd.init
@@ -7,6 +7,8 @@ STOP=01
 USE_PROCD=1
 LLDPCLI=/usr/sbin/lldpcli
 LLDPSOCKET=/var/run/lldpd.socket
+LLDPD_CONF=/tmp/lldpd.conf
+LLDPD_CONFS_DIR=/tmp/lldpd.d
 
 find_release_info()
 {
@@ -17,16 +19,43 @@ find_release_info()
 	echo "${PRETTY_NAME:-Unknown Lede release} @ $(cat /proc/sys/kernel/hostname)"
 }
 
-start_service() {
+write_lldpd_conf()
+{
 	. /lib/functions/network.sh
 
+	local lldp_description
+
+	config_load 'lldpd'
+	config_get lldp_description 'config' 'lldp_description' "$(find_release_info)"
+
+	local ifaces
+	config_get ifaces 'config' 'interface'
+
+	local iface ifnames=""
+	for iface in $ifaces; do
+		local ifname=""
+		if network_get_device ifname "$iface" || [ -e "/sys/class/net/$iface" ]; then
+			append ifnames "${ifname:-$iface}" ","
+		fi
+	done
+
+	# Clear out the config file first
+	echo -n > "$LLDPD_CONF"
+	[ -n "$ifnames" ] && echo "configure system interface pattern" "$ifnames" >> "$LLDPD_CONF"
+	[ -n "$lldp_description" ] && echo "configure system description" "\"$lldp_description\"" >> "$LLDPD_CONF"
+
+	# Since lldpd's sysconfdir is /tmp, we'll symlink /etc/lldpd.d to /tmp/$LLDPD_CONFS_DIR
+	[ -e $LLDPD_CONFS_DIR ] || ln -s /etc/lldpd.d $LLDPD_CONFS_DIR
+}
+
+start_service() {
+
 	local enable_cdp
 	local enable_fdp
 	local enable_sonmp
 	local enable_edp
 	local lldp_class
 	local lldp_location
-	local lldp_description
 	local readonly_mode
 
 	config_load 'lldpd'
@@ -36,35 +65,24 @@ start_service() {
 	config_get_bool enable_edp 'config' 'enable_edp' 0
 	config_get lldp_class 'config' 'lldp_class'
 	config_get lldp_location 'config' 'lldp_location'
-	config_get lldp_description 'config' 'lldp_description' "$(find_release_info)"
 	config_get_bool readonly_mode 'config' 'readonly_mode' 0
 
-	local ifaces
-	config_get ifaces 'config' 'interface'
-
-	local iface ifnames=""
-	for iface in $ifaces; do
-		local ifname=""
-		if network_get_device ifname "$iface" || [ -e "/sys/class/net/$iface" ]; then
-			append ifnames "${ifname:-$iface}" ","
-		fi
-	done
-
 	mkdir -p /var/run/lldp
 	chown lldp:lldp /var/run/lldp
 
+	# When lldpd starts, it also loads up what we write in this config file
+	write_lldpd_conf
+
 	procd_open_instance
 	procd_set_param command /usr/sbin/lldpd
 	procd_append_param command -d # don't daemonize, procd will handle that for us
 
-	[ -n "$ifnames" ] && procd_append_param command -I "$ifnames"
 	[ $enable_cdp -gt 0 ] && procd_append_param command '-c'
 	[ $enable_fdp -gt 0 ] && procd_append_param command '-f'
 	[ $enable_sonmp -gt 0 ] && procd_append_param command '-s'
 	[ $enable_edp -gt 0 ] && procd_append_param command '-e'
 	[ $readonly_mode -gt 0 ] && procd_append_param command '-r'
 	[ -n "$lldp_class" ] && procd_append_param command -M "$lldp_class"
-	[ -n "$lldp_description" ] && procd_append_param command -S "$lldp_description"
 
 	# set auto respawn behavior
 	procd_set_param respawn
@@ -80,10 +98,15 @@ service_running() {
 
 reload_service() {
 	running || return 1
-	# Custom TLVs are special and should be
-	# reloaded from config during lldpd reload
-	$LLDPCLI -u $LLDPSOCKET unconfigure lldp custom-tlv &> /dev/null
-	$LLDPCLI -u $LLDPSOCKET -c /etc/lldpd.conf -c /etc/lldpd.d &> /dev/null
+	$LLDPCLI -u $LLDPSOCKET &> /dev/null <<-EOF
+		unconfigure lldp custom-tlv
+		unconfigure system interface pattern
+		unconfigure system description
+	EOF
+	# Rewrite lldpd.conf
+	# If something changed it should be included by the lldpcli call
+	write_lldpd_conf
+	$LLDPCLI -u $LLDPSOCKET -c $LLDPD_CONF -c $LLDPD_CONFS_DIR &> /dev/null
 	# Broadcast update over the wire
 	$LLDPCLI -u $LLDPSOCKET update &> /dev/null
 	return 0