dnsmasq: write atomic config file

multiple invocation of dnsmasq script (e.g. by procd and hotplugd)
might cause procd to restart dnsmasq with an incomplete config file.
Config file generation might take quite a long time on larger configs
due ubus calls for each listening interface...

Signed-off-by: Ulrich Weber <ulrich.weber@riverbed.com>

diff --git a/package/network/services/dnsmasq/files/dnsmasq.init b/package/network/services/dnsmasq/files/dnsmasq.init
index 5f7afdb95715d563af4dbb35a758d9d39e5cc58e..3809e6c119ffc714517996ac916323162bb74194 100644 (file)
--- a/package/network/services/dnsmasq/files/dnsmasq.init
+++ b/package/network/services/dnsmasq/files/dnsmasq.init
@@ -13,6 +13,7 @@ ADD_LOCAL_DOMAIN=1
 ADD_LOCAL_HOSTNAME=1
 
 CONFIGFILE="/var/etc/dnsmasq.conf"
+CONFIGFILE_TMP="/var/etc/dnsmasq.conf.$$"
 HOSTFILE="/tmp/hosts/dhcp"
 TRUSTANCHORSFILE="/usr/share/dnsmasq/trust-anchors.conf"
 TIMESTAMPFILE="/etc/dnsmasq.time"
@@ -21,7 +22,7 @@ TIMEVALIDFILE="/var/state/dnsmasqsec"
 xappend() {
        local value="$1"
 
-       echo "${value#--}" >> $CONFIGFILE
+       echo "${value#--}" >> $CONFIGFILE_TMP
 }
 
 hex_to_hostid() {
@@ -255,7 +256,7 @@ dnsmasq() {
        xappend "--user=dnsmasq"
        xappend "--group=dnsmasq"
 
-       echo >> $CONFIGFILE
+       echo >> $CONFIGFILE_TMP
 
        config_get_bool enable_tftp "$cfg" enable_tftp 0
        [ "$enable_tftp" -gt 0 ] && {
@@ -635,7 +636,7 @@ start_service() {
 
        [ -f "$TIMESTAMPFILE" ] && rm -f "$TIMESTAMPFILE"
 
-       echo "# auto-generated config file from /etc/config/dhcp" > $CONFIGFILE
+       echo "# auto-generated config file from /etc/config/dhcp" > $CONFIGFILE_TMP
        echo "# auto-generated config file from /etc/config/dhcp" > $HOSTFILE
 
        # if we did this last, we could override auto-generated config
@@ -648,7 +649,7 @@ start_service() {
        args=""
        config_foreach dnsmasq dnsmasq
        config_foreach dhcp_host_add host
-       echo >> $CONFIGFILE
+       echo >> $CONFIGFILE_TMP
        config_foreach dhcp_boot_add boot
        config_foreach dhcp_mac_add mac
        config_foreach dhcp_tag_add tag
@@ -682,19 +683,20 @@ start_service() {
                }
        }
 
-       echo >> $CONFIGFILE
+       echo >> $CONFIGFILE_TMP
        config_foreach dhcp_srv_add srvhost
        config_foreach dhcp_mx_add mxhost
-       echo >> $CONFIGFILE
+       echo >> $CONFIGFILE_TMP
 
        config_get odhcpd_is_active odhcpd maindhcp
        if [ "$odhcpd_is_active" != "1" ]; then
                config_foreach dhcp_add dhcp
        fi
 
-       echo >> $CONFIGFILE
+       echo >> $CONFIGFILE_TMP
        config_foreach dhcp_cname_add cname
-       echo >> $CONFIGFILE
+       echo >> $CONFIGFILE_TMP
+       mv -f $CONFIGFILE_TMP $CONFIGFILE
 
        rm -f /tmp/resolv.conf
        [ $ADD_LOCAL_DOMAIN -eq 1 ] && [ -n "$DOMAIN" ] && {