dbus: connect to bus as soon as the special dbus service is around

dbus-job.c

@@ -128,7 +128,7 @@ static DBusHandlerResult bus_job_message_dispatch(Job *j, DBusMessage *message)
                 return bus_default_message_handler(j->manager, message, introspection, properties);
 
         if (reply) {
-                if (!dbus_connection_send(m->bus, reply, NULL))
+                if (!dbus_connection_send(m->api_bus, reply, NULL))
                         goto oom;
 
                 dbus_message_unref(reply);
@@ -209,7 +209,7 @@ void bus_job_send_change_signal(Job *j) {
                         goto oom;
         }
 
-        if (!dbus_connection_send(j->manager->bus, m, NULL))
+        if (!dbus_connection_send(j->manager->api_bus, m, NULL))
                 goto oom;
 
         free(p);
@@ -249,7 +249,7 @@ void bus_job_send_removed_signal(Job *j) {
                                       DBUS_TYPE_INVALID))
                 goto oom;
 
-        if (!dbus_connection_send(j->manager->bus, m, NULL))
+        if (!dbus_connection_send(j->manager->api_bus, m, NULL))
                 goto oom;
 
         free(p);

dbus-unit.c

@@ -278,7 +278,7 @@ static DBusHandlerResult bus_unit_message_dispatch(Unit *u, DBusMessage *message
         }
 
         if (reply) {
-                if (!dbus_connection_send(m->bus, reply, NULL))
+                if (!dbus_connection_send(m->api_bus, reply, NULL))
                         goto oom;
 
                 dbus_message_unref(reply);
@@ -363,7 +363,7 @@ void bus_unit_send_change_signal(Unit *u) {
                         goto oom;
         }
 
-        if (!dbus_connection_send(u->meta.manager->bus, m, NULL))
+        if (!dbus_connection_send(u->meta.manager->api_bus, m, NULL))
                 goto oom;
 
         free(p);
@@ -405,7 +405,7 @@ void bus_unit_send_removed_signal(Unit *u) {
                                       DBUS_TYPE_INVALID))
                 goto oom;
 
-        if (!dbus_connection_send(u->meta.manager->bus, m, NULL))
+        if (!dbus_connection_send(u->meta.manager->api_bus, m, NULL))
                 goto oom;
 
         free(p);

dbus.c

@@ -31,14 +31,14 @@
 #include "strv.h"
 #include "cgroup.h"
 
-static void bus_dispatch_status(DBusConnection *bus, DBusDispatchStatus status, void *data)  {
+static void api_bus_dispatch_status(DBusConnection *bus, DBusDispatchStatus status, void *data)  {
         Manager *m = data;
 
         assert(bus);
         assert(m);
-        assert(m->bus == bus);
+        assert(m->api_bus == bus);
 
-        m->request_bus_dispatch = status != DBUS_DISPATCH_COMPLETE;
+        m->request_api_bus_dispatch = status != DBUS_DISPATCH_COMPLETE;
 }
 
 static void system_bus_dispatch_status(DBusConnection *bus, DBusDispatchStatus status, void *data)  {
@@ -288,7 +288,7 @@ static void bus_toggle_timeout(DBusTimeout *timeout, void *data) {
                 log_error("Failed to rearm timer: %s", strerror(-r));
 }
 
-static DBusHandlerResult bus_message_filter(DBusConnection  *connection, DBusMessage  *message, void *data) {
+static DBusHandlerResult api_bus_message_filter(DBusConnection  *connection, DBusMessage  *message, void *data) {
         Manager *m = data;
         DBusError error;
 
@@ -305,8 +305,7 @@ static DBusHandlerResult bus_message_filter(DBusConnection  *connection, DBusMes
 
         if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
                 log_error("Warning! D-Bus connection terminated.");
-
+                bus_done_api(m);
-                /* FIXME: we probably should restart D-Bus here */
 
         } else if (dbus_message_is_signal(message, DBUS_INTERFACE_DBUS, "NameOwnerChanged")) {
                 const char *name, *old, *new;
@@ -344,8 +343,7 @@ static DBusHandlerResult system_bus_message_filter(DBusConnection  *connection,
 
         if (dbus_message_is_signal(message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
                 log_error("Warning! D-Bus connection terminated.");
-
+                bus_done_system(m);
-                /* FIXME: we probably should restart D-Bus here */
 
         } if (dbus_message_is_signal(message, "org.freedesktop.systemd1.Agent", "Released")) {
                 const char *cgroup;
@@ -365,9 +363,9 @@ static DBusHandlerResult system_bus_message_filter(DBusConnection  *connection,
 unsigned bus_dispatch(Manager *m) {
         assert(m);
 
-        if (m->request_bus_dispatch)
+        if (m->request_api_bus_dispatch)
-                if (dbus_connection_dispatch(m->bus) == DBUS_DISPATCH_COMPLETE) {
+                if (dbus_connection_dispatch(m->api_bus) == DBUS_DISPATCH_COMPLETE) {
-                        m->request_bus_dispatch = false;
+                        m->request_api_bus_dispatch = false;
                         return 1;
                 }
 
@@ -445,7 +443,7 @@ static int request_name(Manager *m) {
                 return -ENOMEM;
         }
 
-        if (!dbus_connection_send_with_reply(m->bus, message, &pending, -1)) {
+        if (!dbus_connection_send_with_reply(m->api_bus, message, &pending, -1)) {
                 dbus_message_unref(message);
                 return -ENOMEM;
         }
@@ -480,80 +478,40 @@ static int bus_setup_loop(Manager *m, DBusConnection *bus) {
         return 0;
 }
 
-int bus_init(Manager *m) {
+int bus_init_system(Manager *m) {
         DBusError error;
         char *id;
         int r;
 
         assert(m);
 
-        if (m->bus)
+        dbus_error_init(&error);
+
+        if (m->system_bus)
                 return 0;
 
-        if (!(m->subscribed = set_new(string_hash_func, string_compare_func)))
+        if (m->running_as != MANAGER_SESSION && m->api_bus)
-                return -ENOMEM;
+                m->system_bus = m->api_bus;
-
+        else {
-        dbus_connection_set_change_sigpipe(FALSE);
-
-        dbus_error_init(&error);
-        if (!(m->bus = dbus_bus_get_private(m->running_as == MANAGER_SESSION ? DBUS_BUS_SESSION : DBUS_BUS_SYSTEM, &error))) {
-                log_error("Failed to get D-Bus connection: %s", error.message);
-                dbus_error_free(&error);
-                bus_done(m);
-                return -ECONNREFUSED;
-        }
-
-        if ((r = bus_setup_loop(m, m->bus)) < 0) {
-                bus_done(m);
-                return r;
-        }
-
-        dbus_connection_set_dispatch_status_function(m->bus, bus_dispatch_status, m, NULL);
-
-        if (m->running_as == MANAGER_SESSION) {
                 if (!(m->system_bus = dbus_bus_get_private(DBUS_BUS_SYSTEM, &error))) {
-                        log_error("Failed to get D-Bus connection: %s", error.message);
+                        log_error("Failed to get D-Bus connection, retrying later: %s", error.message);
                         dbus_error_free(&error);
-                        bus_done(m);
+                        return 0;
-                        return -ECONNREFUSED;
                 }
 
                 if ((r = bus_setup_loop(m, m->system_bus)) < 0) {
-                        bus_done(m);
+                        bus_done_system(m);
                         return r;
                 }
 
                 dbus_connection_set_dispatch_status_function(m->system_bus, system_bus_dispatch_status, m, NULL);
-        } else
-                m->system_bus = m->bus;
-
-        if (!dbus_connection_register_object_path(m->bus, "/org/freedesktop/systemd1", &bus_manager_vtable, m) ||
-            !dbus_connection_register_fallback(m->bus, "/org/freedesktop/systemd1/unit", &bus_unit_vtable, m) ||
-            !dbus_connection_register_fallback(m->bus, "/org/freedesktop/systemd1/job", &bus_job_vtable, m) ||
-            !dbus_connection_add_filter(m->bus, bus_message_filter, m, NULL) ||
-            !dbus_connection_add_filter(m->system_bus, system_bus_message_filter, m, NULL)) {
-                bus_done(m);
-                return -ENOMEM;
         }
 
-        dbus_bus_add_match(m->bus,
+        if (!dbus_connection_add_filter(m->system_bus, system_bus_message_filter, m, NULL)) {
-                           "type='signal',"
+                bus_done_system(m);
-                           "sender='"DBUS_SERVICE_DBUS"',"
-                           "interface='"DBUS_INTERFACE_DBUS"',"
-                           "path='"DBUS_PATH_DBUS"'",
-                           &error);
-
-        if (dbus_error_is_set(&error)) {
-                log_error("Failed to register match: %s", error.message);
-                dbus_error_free(&error);
                 return -ENOMEM;
         }
 
-        if ((r = request_name(m)) < 0) {
-                bus_done(m);
-                return r;
-        }
-
         dbus_bus_add_match(m->system_bus,
                            "type='signal',"
                            "interface='org.freedesktop.systemd1.Agent',"
@@ -563,39 +521,101 @@ int bus_init(Manager *m) {
         if (dbus_error_is_set(&error)) {
                 log_error("Failed to register match: %s", error.message);
                 dbus_error_free(&error);
-                bus_done(m);
+                bus_done_system(m);
                 return -ENOMEM;
         }
 
-        log_debug("Successfully connected to D-Bus bus %s as %s",
-                  strnull((id = dbus_connection_get_server_id(m->bus))),
-                  strnull(dbus_bus_get_unique_name(m->bus)));
-        dbus_free(id);
-
         log_debug("Successfully connected to system D-Bus bus %s as %s",
                   strnull((id = dbus_connection_get_server_id(m->system_bus))),
                   strnull(dbus_bus_get_unique_name(m->system_bus)));
         dbus_free(id);
 
-        m->request_bus_dispatch = true;
         m->request_system_bus_dispatch = true;
 
         return 0;
 }
 
-void bus_done(Manager *m) {
+int bus_init_api(Manager *m) {
+        DBusError error;
+        char *id;
+        int r;
+
         assert(m);
 
-        if (m->system_bus && m->system_bus != m->bus) {
+        dbus_error_init(&error);
-                dbus_connection_close(m->system_bus);
+
-                dbus_connection_unref(m->system_bus);
+        if (m->api_bus)
-                m->system_bus = NULL;
+                return 0;
+
+        if (m->running_as != MANAGER_SESSION && m->system_bus)
+                m->api_bus = m->system_bus;
+        else {
+                if (!(m->api_bus = dbus_bus_get_private(m->running_as == MANAGER_SESSION ? DBUS_BUS_SESSION : DBUS_BUS_SYSTEM, &error))) {
+                        log_debug("Failed to get D-Bus connection, retrying later: %s", error.message);
+                        dbus_error_free(&error);
+                        return 0;
+                }
+
+                if ((r = bus_setup_loop(m, m->api_bus)) < 0) {
+                        bus_done_api(m);
+                        return r;
+                }
+
+                dbus_connection_set_dispatch_status_function(m->api_bus, api_bus_dispatch_status, m, NULL);
         }
 
-        if (m->bus) {
+        if (!dbus_connection_register_object_path(m->api_bus, "/org/freedesktop/systemd1", &bus_manager_vtable, m) ||
-                dbus_connection_close(m->bus);
+            !dbus_connection_register_fallback(m->api_bus, "/org/freedesktop/systemd1/unit", &bus_unit_vtable, m) ||
-                dbus_connection_unref(m->bus);
+            !dbus_connection_register_fallback(m->api_bus, "/org/freedesktop/systemd1/job", &bus_job_vtable, m) ||
-                m->bus = NULL;
+            !dbus_connection_add_filter(m->api_bus, api_bus_message_filter, m, NULL)) {
+                bus_done_api(m);
+                return -ENOMEM;
+        }
+
+        dbus_bus_add_match(m->api_bus,
+                           "type='signal',"
+                           "sender='"DBUS_SERVICE_DBUS"',"
+                           "interface='"DBUS_INTERFACE_DBUS"',"
+                           "path='"DBUS_PATH_DBUS"'",
+                           &error);
+
+        if (dbus_error_is_set(&error)) {
+                log_error("Failed to register match: %s", error.message);
+                dbus_error_free(&error);
+                bus_done_api(m);
+                return -ENOMEM;
+        }
+
+        if ((r = request_name(m)) < 0) {
+                bus_done_api(m);
+                return r;
+        }
+
+        log_debug("Successfully connected to API D-Bus bus %s as %s",
+                  strnull((id = dbus_connection_get_server_id(m->api_bus))),
+                  strnull(dbus_bus_get_unique_name(m->api_bus)));
+        dbus_free(id);
+
+        if (!m->subscribed)
+                if (!(m->subscribed = set_new(string_hash_func, string_compare_func)))
+                        return -ENOMEM;
+
+        m->request_api_bus_dispatch = true;
+
+        return 0;
+}
+
+void bus_done_api(Manager *m) {
+        assert(m);
+
+        if (m->api_bus) {
+                if (m->system_bus == m->api_bus)
+                        m->system_bus = NULL;
+
+                dbus_connection_close(m->api_bus);
+                dbus_connection_unref(m->api_bus);
+                m->api_bus = NULL;
+
         }
 
         if (m->subscribed) {
@@ -609,6 +629,19 @@ void bus_done(Manager *m) {
         }
 }
 
+void bus_done_system(Manager *m) {
+        assert(m);
+
+        if (m->system_bus == m->api_bus)
+                bus_done_api(m);
+
+        if (m->system_bus) {
+                dbus_connection_close(m->system_bus);
+                dbus_connection_unref(m->system_bus);
+                m->system_bus = NULL;
+        }
+}
+
 DBusHandlerResult bus_default_message_handler(Manager *m, DBusMessage *message, const char*introspection, const BusProperty *properties) {
         DBusError error;
         DBusMessage *reply = NULL;
@@ -717,7 +750,7 @@ DBusHandlerResult bus_default_message_handler(Manager *m, DBusMessage *message,
         }
 
         if (reply) {
-                if (!dbus_connection_send(m->bus, reply, NULL))
+                if (!dbus_connection_send(m->api_bus, reply, NULL))
                         goto oom;
 
                 dbus_message_unref(reply);
@@ -788,7 +821,7 @@ DBusHandlerResult bus_send_error_reply(Manager *m, DBusMessage *message, DBusErr
         if (!(reply = dbus_message_new_error(message, name, text)))
                 goto oom;
 
-        if (!dbus_connection_send(m->bus, reply, NULL))
+        if (!dbus_connection_send(m->api_bus, reply, NULL))
                 goto oom;
 
         dbus_message_unref(reply);

dbus.h

@@ -56,8 +56,10 @@ typedef struct BusProperty {
         "  </method>"                                                   \
         " </interface>"
 
-int bus_init(Manager *m);
+int bus_init_system(Manager *m);
-void bus_done(Manager *m);
+int bus_init_api(Manager *m);
+void bus_done_system(Manager *m);
+void bus_done_api(Manager *m);
 
 unsigned bus_dispatch(Manager *m);
 

manager.c

@@ -315,8 +315,11 @@ int manager_new(Manager **_m) {
         if ((r = manager_setup_cgroup(m)) < 0)
                 goto fail;
 
-        /* FIXME: this should be called only when the D-Bus bus daemon is running */
+        dbus_connection_set_change_sigpipe(FALSE);
-        if ((r = bus_init(m)) < 0)
+
+        /* Try to connect to the busses, if possible. */
+        if ((r = bus_init_system(m)) < 0 ||
+            (r = bus_init_api(m)) < 0)
                 goto fail;
 
         *_m = m;
@@ -364,7 +367,8 @@ void manager_free(Manager *m) {
 
         manager_shutdown_cgroup(m);
 
-        bus_done(m);
+        bus_done_api(m);
+        bus_done_system(m);
 
         hashmap_free(m->units);
         hashmap_free(m->jobs);

manager.h

@@ -135,7 +135,7 @@ struct Manager {
         bool dispatching_run_queue:1;
         bool dispatching_dbus_queue:1;
 
-        bool request_bus_dispatch:1;
+        bool request_api_bus_dispatch:1;
         bool request_system_bus_dispatch:1;
 
         Hashmap *watch_pids;  /* pid => Unit object n:1 */
@@ -157,7 +157,7 @@ struct Manager {
         Watch mount_watch;
 
         /* Data specific to the D-Bus subsystem */
-        DBusConnection *bus, *system_bus;
+        DBusConnection *api_bus, *system_bus;
         Set *subscribed;
 
         /* Data specific to the cgroup subsystem */

service.c

@@ -732,7 +732,6 @@ static void service_dump(Unit *u, FILE *f, const char *prefix) {
                         "%sPIDFile: %s\n",
                         prefix, s->pid_file);
 
-
         exec_context_dump(&s->exec_context, f, prefix);
 
         for (c = 0; c < _SERVICE_EXEC_MAX; c++) {

unit.c

@@ -131,6 +131,13 @@ Unit *unit_new(Manager *m) {
         return u;
 }
 
+bool unit_has_name(Unit *u, const char *name) {
+        assert(u);
+        assert(name);
+
+        return !!set_get(u->meta.names, (char*) name);
+}
+
 int unit_add_name(Unit *u, const char *text) {
         UnitType t;
         char *s;
@@ -906,6 +913,28 @@ void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns) {
         else if (UNIT_IS_ACTIVE_OR_ACTIVATING(os) && UNIT_IS_INACTIVE_OR_DEACTIVATING(ns))
                 retroactively_stop_dependencies(u);
 
+        if (!UNIT_IS_ACTIVE_OR_RELOADING(os) && UNIT_IS_ACTIVE_OR_RELOADING(ns)) {
+
+                if (unit_has_name(u, SPECIAL_DBUS_SERVICE)) {
+                        /* The bus just got started, hence try to connect to it. */
+                        bus_init_system(u->meta.manager);
+                        bus_init_api(u->meta.manager);
+                }
+
+                if (unit_has_name(u, SPECIAL_SYSLOG_SERVICE))
+                        /* The syslog daemon just got started, hence try to connect to it. */
+                        log_info("Syslog now available, this is where we should start logging to it.");
+
+        } else if (UNIT_IS_ACTIVE_OR_RELOADING(os) && !UNIT_IS_ACTIVE_OR_RELOADING(ns)) {
+
+                if (unit_has_name(u, SPECIAL_SYSLOG_SERVICE))
+                        /* The syslog daemon just got terminated, hence try to disconnect from it. */
+                        log_info("Syslog now gone, this is where we should stio logging to it.");
+
+                /* We don't care about D-Bus here, since we'll get an
+                 * asynchronous notification for it anyway. */
+        }
+
         /* Maybe we finished startup and are now ready for being
          * stopped because unneeded? */
         unit_check_uneeded(u);

unit.h

@@ -284,6 +284,8 @@ int unit_load(Unit *unit);
 const char* unit_id(Unit *u);
 const char *unit_description(Unit *u);
 
+bool unit_has_name(Unit *u, const char *name);
+
 UnitActiveState unit_active_state(Unit *u);
 
 void unit_dump(Unit *u, FILE *f, const char *prefix);