core: unify code for checking whether unit to trigger is loaded

src/core/automount.c

@@ -796,7 +796,6 @@ fail:
 
 static int automount_start(Unit *u) {
         Automount *a = AUTOMOUNT(u);
-        Unit *trigger;
         int r;
 
         assert(a);
@@ -807,11 +806,9 @@ static int automount_start(Unit *u) {
                 return -EEXIST;
         }
 
-        trigger = UNIT_TRIGGER(u);
-        if (!trigger || trigger->load_state != UNIT_LOADED) {
-                log_unit_error(u, "Refusing to start, unit to trigger not loaded.");
-                return -ENOENT;
-        }
+        r = unit_test_trigger_loaded(u);
+        if (r < 0)
+                return r;
 
         r = unit_test_start_limit(u);
         if (r < 0) {

src/core/path.c

@@ -555,17 +555,14 @@ static void path_mkdir(Path *p) {
 
 static int path_start(Unit *u) {
         Path *p = PATH(u);
-        Unit *trigger;
         int r;
 
         assert(p);
         assert(IN_SET(p->state, PATH_DEAD, PATH_FAILED));
 
-        trigger = UNIT_TRIGGER(u);
-        if (!trigger || trigger->load_state != UNIT_LOADED) {
-                log_unit_error(u, "Refusing to start, unit to trigger not loaded.");
-                return -ENOENT;
-        }
+        r = unit_test_trigger_loaded(u);
+        if (r < 0)
+                return r;
 
         r = unit_test_start_limit(u);
         if (r < 0) {

src/core/timer.c

@@ -595,17 +595,14 @@ fail:
 static int timer_start(Unit *u) {
         Timer *t = TIMER(u);
         TimerValue *v;
-        Unit *trigger;
         int r;
 
         assert(t);
         assert(IN_SET(t->state, TIMER_DEAD, TIMER_FAILED));
 
-        trigger = UNIT_TRIGGER(u);
-        if (!trigger || trigger->load_state != UNIT_LOADED) {
-                log_unit_error(u, "Refusing to start, unit to trigger not loaded.");
-                return -ENOENT;
-        }
+        r = unit_test_trigger_loaded(u);
+        if (r < 0)
+                return r;
 
         r = unit_test_start_limit(u);
         if (r < 0) {

src/core/unit.c

@@ -1736,6 +1736,7 @@ static bool unit_verify_deps(Unit *u) {
  *         -EOPNOTSUPP: Unit type not supported
  *         -ENOLINK:    The necessary dependencies are not fulfilled.
  *         -ESTALE:     This unit has been started before and can't be started a second time
+ *         -ENOENT:     This is a triggering unit and unit to trigger is not loaded
  */
 int unit_start(Unit *u) {
         UnitActiveState state;
@@ -5590,6 +5591,20 @@ int unit_success_action_exit_status(Unit *u) {
         return r;
 }
 
+int unit_test_trigger_loaded(Unit *u) {
+        Unit *trigger;
+
+        /* Tests whether the unit to trigger is loaded */
+
+        trigger = UNIT_TRIGGER(u);
+        if (!trigger)
+                return log_unit_error_errno(u, SYNTHETIC_ERRNO(ENOENT), "Refusing to start, unit to trigger not loaded.");
+        if (trigger->load_state != UNIT_LOADED)
+                return log_unit_error_errno(u, SYNTHETIC_ERRNO(ENOENT), "Refusing to start, unit %s to trigger not loaded.", u->id);
+
+        return 0;
+}
+
 static const char* const collect_mode_table[_COLLECT_MODE_MAX] = {
         [COLLECT_INACTIVE] = "inactive",
         [COLLECT_INACTIVE_OR_FAILED] = "inactive-or-failed",

src/core/unit.h

@@ -830,6 +830,8 @@ int unit_exit_status(Unit *u);
 int unit_success_action_exit_status(Unit *u);
 int unit_failure_action_exit_status(Unit *u);
 
+int unit_test_trigger_loaded(Unit *u);
+
 /* Macros which append UNIT= or USER_UNIT= to the message */
 
 #define log_unit_full(unit, level, error, ...)                          \