unit: add DefaultDependencies= setting

In order to simplify writing of unit files introduce default
dependencies that are added to all units unless explictly disabled in a
unit. This option can be switched off for select units that are involved
in early boot-up ot late system shutdown,

This should simplify service files for most normal daemons, but breaks
existing service files for software involved in early boot (notably
udev), which need to be updated for a DefaultDependencies=no setting)

1 files changed, 36 insertions, 6 deletions

diff --git a/src/service.c b/src/service.c
index cbc9c9551a..04ed684393 100644
--- a/src/service.c
+++ b/src/service.c
@@ -665,20 +665,18 @@ static int service_load_sysv_path(Service *s, const char *path) {
         if ((r = sysv_exec_commands(s)) < 0)
                 goto finish;
 
-        if (!s->sysv_runlevels || chars_intersect(RUNLEVELS_UP, s->sysv_runlevels)) {
+        if (s->sysv_runlevels && !chars_intersect(RUNLEVELS_UP, s->sysv_runlevels)) {
                 /* If there a runlevels configured for this service
                  * but none of the standard ones, then we assume this
                  * is some special kind of service (which might be
                  * needed for early boot) and don't create any links
                  * to it. */
 
-                if ((r = unit_add_dependency_by_name(u, UNIT_REQUIRES, SPECIAL_BASIC_TARGET, NULL, true)) < 0 ||
-                    (r = unit_add_dependency_by_name(u, UNIT_AFTER, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
-                        goto finish;
+                s->meta.default_dependencies = false;
 
-        } else
                 /* Don't timeout special services during boot (like fsck) */
                 s->timeout_usec = 0;
+        }
 
         /* Special setting for all SysV services */
         s->type = SERVICE_FORKING;
@@ -827,6 +825,30 @@ static int service_verify(Service *s) {
         return 0;
 }
 
+static int service_add_default_dependencies(Service *s) {
+        int r;
+
+        assert(s);
+
+        /* Add a number of automatic dependencies useful for the
+         * majority of services. */
+
+        /* First, pull in base system */
+        if (s->meta.manager->running_as == MANAGER_SYSTEM) {
+
+                if ((r = unit_add_two_dependencies_by_name(UNIT(s), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_BASIC_TARGET, NULL, true)) < 0)
+                        return r;
+
+        } else if (s->meta.manager->running_as == MANAGER_SESSION) {
+
+                if ((r = unit_add_two_dependencies_by_name(UNIT(s), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SOCKETS_TARGET, NULL, true)) < 0)
+                        return r;
+        }
+
+        /* Second, activate normal shutdown */
+        return unit_add_two_dependencies_by_name(UNIT(s), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, NULL, true);
+}
+
 static int service_load(Unit *u) {
         int r;
         Service *s = SERVICE(u);
@@ -867,11 +889,19 @@ static int service_load(Unit *u) {
                                 return r;
 
                         if ((r = unit_watch_bus_name(u, s->bus_name)) < 0)
-                            return r;
+                                return r;
                 }
 
                 if (s->type == SERVICE_NOTIFY && s->notify_access == NOTIFY_NONE)
                         s->notify_access = NOTIFY_MAIN;
+
+                if (s->type == SERVICE_DBUS || s->bus_name)
+                        if ((r = unit_add_two_dependencies_by_name(u, UNIT_AFTER, UNIT_REQUIRES, SPECIAL_DBUS_TARGET, NULL, true)) < 0)
+                                return r;
+
+                if (s->meta.default_dependencies)
+                        if ((r = service_add_default_dependencies(s)) < 0)
+                                return r;
         }
 
         return service_verify(s);