add support for systemd notification protocol

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

configure.ac

@@ -12,6 +12,8 @@ AC_CONFIG_HEADERS([orconfig.h])
 
 AC_CANONICAL_HOST
 
+PKG_PROG_PKG_CONFIG
+
 if test -f /etc/redhat-release ; then
   if test -f /usr/kerberos/include ; then
     CPPFLAGS="$CPPFLAGS -I/usr/kerberos/include"
@@ -105,6 +107,37 @@ AC_ARG_ENABLE(upnp,
         * ) AC_MSG_ERROR(bad value for --enable-upnp) ;;
       esac], [upnp=false])
 
+# systemd notify support
+AC_ARG_ENABLE(systemd,
+      AS_HELP_STRING(--enable-systemd, enable systemd notification support),
+      [case "${enableval}" in
+        yes) systemd=true ;;
+        no)  systemd=false ;;
+        * ) AC_MSG_ERROR(bad value for --enable-systemd) ;;
+      esac], [systemd=auto])
+
+
+
+# systemd support
+if test x$enable_systemd = xfalse ; then
+    have_systemd=no;
+else
+    PKG_CHECK_MODULES(SYSTEMD,
+        [libsystemd-daemon],
+        have_systemd=yes,
+        have_systemd=no)
+fi
+
+if test x$have_systemd = xyes; then
+    AC_DEFINE(HAVE_SYSTEMD,1,[Have systemd])
+    TOR_SYSTEMD_LIBS="-lsystemd-daemon"
+fi
+AC_SUBST(TOR_SYSTEMD_LIBS)
+
+if test x$enable_systemd = xyes -a x$have_systemd != xyes ; then
+    AC_MSG_ERROR([Explicitly requested systemd support, but systemd not found])
+fi
+
 case $host in
    *-*-solaris* )
      AC_DEFINE(_REENTRANT, 1, [Define on some platforms to activate x_r() functions in time.h])
@@ -618,7 +651,7 @@ dnl since sometimes the linker will like an option but not be willing to
 dnl use it with a build of a library.
 
 all_ldflags_for_check="$TOR_LDFLAGS_zlib $TOR_LDFLAGS_openssl $TOR_LDFLAGS_libevent"
-all_libs_for_check="$TOR_ZLIB_LIBS $TOR_LIB_MATH $TOR_LIBEVENT_LIBS $TOR_OPENSSL_LIBS $TOR_LIB_WS32 $TOR_LIB_GDI"
+all_libs_for_check="$TOR_ZLIB_LIBS $TOR_LIB_MATH $TOR_LIBEVENT_LIBS $TOR_OPENSSL_LIBS $TOR_SYSTEMD_LIBS $TOR_LIB_WS32 $TOR_LIB_GDI"
 
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
 #if !defined(__clang__)

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;

src/test/include.am

@@ -68,7 +68,8 @@ src_test_test_LDADD = src/or/libtor-testing.a src/common/libor-testing.a \
 	src/common/libor-crypto-testing.a $(LIBDONNA) \
 	src/common/libor-event-testing.a src/trunnel/libor-trunnel-testing.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
-	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@
+	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
+	@TOR_SYSTEMD_LIBS@
 
 src_test_bench_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \
         @TOR_LDFLAGS_libevent@
@@ -76,7 +77,8 @@ src_test_bench_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_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
+	@TOR_SYSTEMD_LIBS@
 
 noinst_HEADERS+= \
 	src/test/fakechans.h \