add support for systemd notification protocol

This permit for now to signal readiness in a cleaner way
to systemd.

src/or/include.am

@@ -111,7 +111,7 @@ src_or_tor_LDADD = src/or/libtor.a src/common/libor.a \
 	src/common/libor-crypto.a $(LIBDONNA) \
 	src/common/libor-event.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ @TOR_OPENSSL_LIBS@ \
-	@TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@
+	@TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ @TOR_SYSTEMD_LIBS@
 
 if COVERAGE_ENABLED
 src_or_tor_cov_SOURCES = src/or/tor_main.c
@@ -122,7 +122,7 @@ src_or_tor_cov_LDADD = src/or/libtor-testing.a src/common/libor-testing.a \
 	src/common/libor-crypto-testing.a $(LIBDONNA) \
 	src/common/libor-event-testing.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ @TOR_OPENSSL_LIBS@ \
-	@TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@
+	@TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ @TOR_SYSTEMD_LIBS@
 endif
 
 ORHEADERS = \

src/or/main.c

@@ -75,6 +75,10 @@
 #include <event2/bufferevent.h>
 #endif
 
+#ifdef HAVE_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 void evdns_shutdown(int);
 
 /********* PROTOTYPES **********/
@@ -2043,6 +2047,11 @@ do_main_loop(void)
   }
 #endif
 
+#ifdef HAVE_SYSTEMD
+  log_notice(LD_GENERAL, "Signaling readyness to systemd");
+  sd_notify(0, "READY=1");
+#endif
+
   for (;;) {
     if (nt_service_is_stopping())
       return 0;