make libsystemd optional

README.rst

@@ -13,12 +13,12 @@ You need:
 - a C++20 compliant compiler (e.g. gcc or clang)
 - `libfmt <https://fmt.dev/>`__
 - `LuaJIT <http://luajit.org/>`__
-- `systemd <https://www.freedesktop.org/wiki/Software/systemd/>`__
 - `Meson 0.56 <http://mesonbuild.com/>`__ and `Ninja <https://ninja-build.org/>`__
 
 Optional dependencies:
 
 - `libsodium <https://www.libsodium.org/>`__
+- `systemd <https://www.freedesktop.org/wiki/Software/systemd/>`__
 
 Get the source code::
 

debian/changelog

@@ -1,6 +1,7 @@
 cm4all-passage (0.19) unstable; urgency=low
 
   * lua: add libsodium bindings
+  * make libsystemd optional
 
  --   
 

meson.build

@@ -96,7 +96,7 @@ add_global_arguments(common_flags, language: 'cpp')
 add_global_arguments(compiler.get_supported_arguments(test_global_cxxflags), language: 'cpp')
 add_project_arguments(compiler.get_supported_arguments(test_cxxflags), language: 'cpp')
 
-libsystemd = dependency('libsystemd')
+libsystemd = dependency('libsystemd', required: get_option('systemd'))
 
 inc = include_directories('src', 'libcommon/src')
 
@@ -114,10 +114,14 @@ subdir('libcommon/src/event')
 subdir('libcommon/src/net')
 subdir('libcommon/src/net/control')
 subdir('libcommon/src/event/net')
-subdir('libcommon/src/event/systemd')
 subdir('libcommon/src/lua/io')
 subdir('libcommon/src/lua/net')
 
+if libsystemd.found()
+  subdir('libcommon/src/event/systemd')
+  libsystemd = event_systemd_dep
+endif
+
 if sodium_dep.found()
   subdir('libcommon/src/lua/sodium')
 else
@@ -133,6 +137,7 @@ spawn_dep = declare_dependency(link_with: spawn,
                                dependencies: [event_dep])
 
 conf.set('HAVE_LIBSODIUM', sodium_dep.found())
+conf.set('HAVE_LIBSYSTEMD', libsystemd.found())
 configure_file(output: 'config.h', configuration: conf)
 
 executable('cm4all-passage',
@@ -160,7 +165,7 @@ executable('cm4all-passage',
     lua_sodium_dep,
     control_client_dep,
     event_net_dep,
-    event_systemd_dep,
+    libsystemd,
     spawn_dep,
     fmt_dep,
   ],

meson_options.txt

@@ -1,4 +1,5 @@
 option('sodium', type: 'feature', description: 'libsodium support')
+option('systemd', type: 'feature', description: 'systemd support (using libsystemd)')
 
 option('documentation', type: 'feature',
   description: 'Build documentation')

src/Instance.cxx

@@ -11,7 +11,9 @@ extern "C" {
 #include <lauxlib.h>
 }
 
+#ifdef HAVE_LIBSYSTEMD
 #include <systemd/sd-daemon.h>
+#endif
 
 #include <stdexcept>
 
@@ -55,6 +57,8 @@ Instance::AddListener(SocketAddress address, Lua::ValuePtr &&handler)
 	AddListener(MakeListener(address), std::move(handler));
 }
 
+#ifdef HAVE_LIBSYSTEMD
+
 void
 Instance::AddSystemdListener(Lua::ValuePtr &&handler)
 {
@@ -70,6 +74,8 @@ Instance::AddSystemdListener(Lua::ValuePtr &&handler)
 			    Lua::ValuePtr(handler));
 }
 
+#endif // HAVE_LIBSYSTEMD
+
 void
 Instance::Check()
 {
@@ -83,7 +89,9 @@ Instance::OnShutdown() noexcept
 	shutdown_listener.Disable();
 	sighup_event.Disable();
 
+#ifdef HAVE_LIBSYSTEMD
 	systemd_watchdog.Disable();
+#endif
 
 	event_loop.Break();
 }

src/Instance.hxx

@@ -13,7 +13,11 @@
 #include "event/Loop.hxx"
 #include "event/ShutdownListener.hxx"
 #include "event/SignalEvent.hxx"
+#include "config.h"
+
+#ifdef HAVE_LIBSYSTEMD
 #include "event/systemd/Watchdog.hxx"
+#endif
 
 #include <forward_list>
 
@@ -25,7 +29,9 @@ class Instance final {
 	ShutdownListener shutdown_listener{event_loop, BIND_THIS_METHOD(OnShutdown)};
 	SignalEvent sighup_event;
 
+#ifdef HAVE_LIBSYSTEMD
 	Systemd::Watchdog systemd_watchdog{event_loop};
+#endif
 
 	ZombieReaper zombie_reaper{event_loop};
 
@@ -55,11 +61,13 @@ public:
 	void AddListener(SocketAddress address,
 			 Lua::ValuePtr &&handler);
 
+#ifdef HAVE_LIBSYSTEMD
 	/**
 	 * Listen for incoming connections on sockets passed by systemd
 	 * (systemd socket activation).
 	 */
 	void AddSystemdListener(Lua::ValuePtr &&handler);
+#endif // HAVE_LIBSYSTEMD
 
 	void Check();
 

src/Main.cxx

@@ -28,12 +28,16 @@ extern "C" {
 #include <lualib.h>
 }
 
+#ifdef HAVE_LIBSYSTEMD
 #include <systemd/sd-daemon.h>
+#endif
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h> // for chdir()
 
+#ifdef HAVE_LIBSYSTEMD
+
 static int systemd_magic = 42;
 
 static bool
@@ -43,6 +47,8 @@ IsSystemdMagic(lua_State *L, int idx)
 		lua_touserdata(L, idx) == &systemd_magic;
 }
 
+#endif // HAVE_LIBSYSTEMD
+
 static int
 l_passage_listen(lua_State *L)
 try {
@@ -56,15 +62,17 @@ try {
 
 	auto handler = std::make_shared<Lua::Value>(L, Lua::StackIndex(2));
 
-	if (IsSystemdMagic(L, 1)) {
-		instance.AddSystemdListener(std::move(handler));
-	} else if (lua_isstring(L, 1)) {
+	if (lua_isstring(L, 1)) {
 		const char *address_string = lua_tostring(L, 1);
 
 		AllocatedSocketAddress address;
 		address.SetLocal(address_string);
 
 		instance.AddListener(address, std::move(handler));
+#ifdef HAVE_LIBSYSTEMD
+	} if (IsSystemdMagic(L, 1)) {
+		instance.AddSystemdListener(std::move(handler));
+#endif
 	} else
 		luaL_argerror(L, 1, "path expected");
 
@@ -85,7 +93,9 @@ SetupConfigState(lua_State *L, Instance &instance)
 	Lua::InitSocketAddress(L);
 	RegisterLuaResolver(L);
 
+#ifdef HAVE_LIBSYSTEMD
 	Lua::SetGlobal(L, "systemd", Lua::LightUserData(&systemd_magic));
+#endif
 
 	Lua::SetGlobal(L, "passage_listen",
 		       Lua::MakeCClosure(l_passage_listen,
@@ -139,8 +149,10 @@ Run(const CommandLine &cmdline)
 
 	SetupRuntimeState(instance.GetLuaState());
 
+#ifdef HAVE_LIBSYSTEMD
 	/* tell systemd we're ready */
 	sd_notify(0, "READY=1");
+#endif
 
 	instance.GetEventLoop().Run();