unit: introduce exit.service for exiting from session instances

Makefile.am

@@ -128,7 +128,8 @@ dist_sessionunit_DATA = \
 	units/session/default.target
 
 sessionunit_DATA = \
-	units/session/remote-fs.target
+	units/session/remote-fs.target \
+	units/session/exit.service
 
 EXTRA_DIST = \
 	units/basic.target.m4 \
@@ -139,6 +140,7 @@ EXTRA_DIST = \
 	units/systemd-initctl.service.in \
 	units/systemd-logger.service.in \
 	units/syslog.target.in \
+	units/session/exit.service.in \
 	LICENSE \
 	README \
 	DISTRO_PORTING
@@ -359,6 +361,8 @@ SED_PROCESS = \
 	$(SED)  -e 's,@libexecdir\@,$(libexecdir),g' \
 		-e 's,@pkglibexecdir\@,$(pkglibexecdir),g' \
 		-e 's,@SPECIAL_SYSLOG_SERVICE\@,$(SPECIAL_SYSLOG_SERVICE),g' \
+		-e 's,@SPECIAL_DBUS_SERVICE\@,$(SPECIAL_DBUS_SERVICE),g' \
+		-e 's,@SYSTEMCTL\@,$(bindir)/systemctl,g' \
 		< $< > $@
 
 units/%: units/%.in Makefile
@@ -391,6 +395,7 @@ CLEANFILES = \
 	units/multi-user.target \
 	units/remote-fs.target \
 	units/session/remote-fs.target \
+	units/session/exit.service \
 	man/systemd.special.7 \
 	man/systemd.special.html
 

fixme

@@ -64,8 +64,6 @@
 
 * tcpwrap
 
-* introduce exit.target for session instances
-
 Regularly:
 
 * look for close() vs. close_nointr() vs. close_nointr_nofail()

man/systemd.special.xml.in

@@ -53,6 +53,7 @@
                 <filename>default.target</filename>,
                 <filename>display-manager.service</filename>,
                 <filename>emergency.service</filename>,
+                <filename>exit.service</filename>,
                 <filename>graphical.target</filename>,
                 <filename>halt.target</filename>,
                 <filename>kbrequest.target</filename>,
@@ -635,6 +636,35 @@
                 <filename>shutdown.target</filename>,
                 <filename>sockets.target</filename>,
                 <filename>swap.target</filename>.</para>
+
+                <para>In addition the following special unit is
+                understood only when systemd runs as service instance:</para>
+
+                <variablelist>
+                        <varlistentry>
+                                <term><filename>exit.service</filename></term>
+                                <listitem>
+                                        <para>A special service unit
+                                        for shutting down the
+                                        session.</para>
+
+                                        <para>Applications wanting to
+                                        terminate the session should
+                                        start this unit. If systemd
+                                        receives SIGTERM or SIGINT
+                                        when running as session daemon
+                                        it will start this
+                                        unit.</para>
+
+                                        <para>Normally, this pulls in
+                                        <filename>shutdown.target</filename>
+                                        which in turn should be
+                                        conflicted by all units that
+                                        want to be shut down on
+                                        session exit.</para>
+                                </listitem>
+                        </varlistentry>
+                </variablelist>
         </refsect1>
 
         <refsect1>

src/manager.c

@@ -1791,11 +1791,13 @@ static int manager_dispatch_sigchld(Manager *m) {
         return 0;
 }
 
-static void manager_start_target(Manager *m, const char *name) {
+static int manager_start_target(Manager *m, const char *name) {
         int r;
 
         if ((r = manager_add_job_by_name(m, JOB_START, name, JOB_REPLACE, true, NULL)) < 0)
                 log_error("Failed to enqueue %s job: %s", name, strerror(-r));
+
+        return r;
 }
 
 static int manager_process_signal_fd(Manager *m) {
@@ -1824,14 +1826,14 @@ static int manager_process_signal_fd(Manager *m) {
                         break;
 
                 case SIGTERM:
-                        if (m->running_as == MANAGER_INIT)
+                        if (m->running_as == MANAGER_INIT) {
                                 /* This is for compatibility with the
                                  * original sysvinit */
                                 m->exit_code = MANAGER_REEXECUTE;
-                        else
-                                m->exit_code = MANAGER_EXIT;
+                                break;
+                        }
 
-                        return 0;
+                        /* Fall through */
 
                 case SIGINT:
                         if (m->running_as == MANAGER_INIT) {
@@ -1839,8 +1841,13 @@ static int manager_process_signal_fd(Manager *m) {
                                 break;
                         }
 
-                        m->exit_code = MANAGER_EXIT;
-                        return 0;
+                        /* Run the exit target if there is one, if not, just exit. */
+                        if (manager_start_target(m, SPECIAL_EXIT_SERVICE) < 0) {
+                                m->exit_code = MANAGER_EXIT;
+                                return 0;
+                        }
+
+                        break;
 
                 case SIGWINCH:
                         if (m->running_as == MANAGER_INIT)

src/manager.h

@@ -109,6 +109,7 @@ struct Watch {
 #define SPECIAL_MAIL_TRANSFER_AGENT_TARGET "mail-transfer-agent.target" /* Debian's $mail-{transport|transfer-agent */
 #define SPECIAL_BASIC_TARGET "basic.target"
 #define SPECIAL_RESCUE_TARGET "rescue.target"
+#define SPECIAL_EXIT_SERVICE "exit.service"
 
 #ifndef SPECIAL_DBUS_SERVICE
 #define SPECIAL_DBUS_SERVICE "dbus.service"

units/session/.gitignore

@@ -0,0 +1 @@
+exit.service

units/session/exit.service.in

@@ -0,0 +1,8 @@
+[Unit]
+Description=Exit
+Requires=shutdown.target
+After=shutdown.target
+
+[Service]
+Type=finish
+ExecStart=@SYSTEMCTL@ --session daemon-exit