core: allow services with no commands but SuccessAction set

diff --git a/src/core/service.c b/src/core/service.c
index 5472e1a..03e6792 100644 (file)
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -538,8 +538,13 @@ static int service_verify(Service *s) {
         if (UNIT(s)->load_state != UNIT_LOADED)
                 return 0;
 
-        if (!s->exec_command[SERVICE_EXEC_START] && !s->exec_command[SERVICE_EXEC_STOP]) {
-                log_unit_error(UNIT(s), "Service lacks both ExecStart= and ExecStop= setting. Refusing.");
+        if (!s->exec_command[SERVICE_EXEC_START] && !s->exec_command[SERVICE_EXEC_STOP]
+            && UNIT(s)->success_action == EMERGENCY_ACTION_NONE) {
+                /* FailureAction= only makes sense if one of the start or stop commands is specified.
+                 * SuccessAction= will be executed unconditionally if no commands are specified. Hence,
+                 * either a command or SuccessAction= are required. */
+
+                log_unit_error(UNIT(s), "Service has no ExecStart=, ExecStop=, or SuccessAction=. Refusing.");
                 return -ENOEXEC;
         }
 
@@ -548,8 +553,8 @@ static int service_verify(Service *s) {
                 return -ENOEXEC;
         }
 
-        if (!s->remain_after_exit && !s->exec_command[SERVICE_EXEC_START]) {
-                log_unit_error(UNIT(s), "Service has no ExecStart= setting, which is only allowed for RemainAfterExit=yes services. Refusing.");
+        if (!s->remain_after_exit && !s->exec_command[SERVICE_EXEC_START] && UNIT(s)->success_action == EMERGENCY_ACTION_NONE) {
+                log_unit_error(UNIT(s), "Service has no ExecStart= and no SuccessAction= settings and does not have RemainAfterExit=yes set. Refusing.");
                 return -ENOEXEC;
         }