adjust lighttpd config depending on whether or not custom.php exists

Signed-off-by: Adam Warner <adamw@rner.email>

automated install/basic-install.sh

@@ -1082,6 +1082,10 @@ installConfigs() {
     fi
     # and copy in the config file Pi-hole needs
     cp ${PI_HOLE_LOCAL_REPO}/advanced/${LIGHTTPD_CFG} /etc/lighttpd/lighttpd.conf
+    # if there is a custom block page in the html/pihole directory, replace 404 handler in lighttpd config
+    if [[ -f "/var/www/html/pihole/custom.php" ]]; then
+      sed -i 's/^\(server\.error-handler-404\s*=\s*\).*$/\1"pihole\/custom\.php"/' /etc/lighttpd/lighttpd.conf
+    fi
     # Make the directories if they do not exist and set the owners
     mkdir -p /var/run/lighttpd
     chown ${LIGHTTPD_USER}:${LIGHTTPD_GROUP} /var/run/lighttpd