core: set Result=start-limit-hit when a unit is rate limited

There is currently no way to figure out a rate limit was hit on a unit,
as the last result is stripped in order to keep reporting the first
result, which is useful in case of a watchdog failure, which is the
reason why it was changed as such.

But rate limiting is also an important information to provide to
users, so allow the Result property to reflect it when it
happens.

src/core/automount.c

@@ -324,7 +324,7 @@ static void automount_dump(Unit *u, FILE *f, const char *prefix) {
 static void automount_enter_dead(Automount *a, AutomountResult f) {
         assert(a);
 
-        if (a->result == AUTOMOUNT_SUCCESS)
+        if (a->result == AUTOMOUNT_SUCCESS || IN_SET(f, AUTOMOUNT_FAILURE_MOUNT_START_LIMIT_HIT, AUTOMOUNT_FAILURE_START_LIMIT_HIT))
                 a->result = f;
 
         unit_log_result(UNIT(a), a->result == AUTOMOUNT_SUCCESS, automount_result_to_string(a->result));

src/core/mount.c

@@ -893,7 +893,7 @@ static int mount_spawn(Mount *m, ExecCommand *c, ExecFlags flags, PidRef *ret_pi
 static void mount_enter_dead(Mount *m, MountResult f, bool flush_result) {
         assert(m);
 
-        if (m->result == MOUNT_SUCCESS || flush_result)
+        if (m->result == MOUNT_SUCCESS || f == MOUNT_FAILURE_START_LIMIT_HIT || flush_result)
                 m->result = f;
 
         unit_log_result(UNIT(m), m->result == MOUNT_SUCCESS, mount_result_to_string(m->result));

src/core/path.c

@@ -502,7 +502,7 @@ static int path_coldplug(Unit *u) {
 static void path_enter_dead(Path *p, PathResult f) {
         assert(p);
 
-        if (p->result == PATH_SUCCESS)
+        if (p->result == PATH_SUCCESS || IN_SET(f, PATH_FAILURE_START_LIMIT_HIT, PATH_FAILURE_UNIT_START_LIMIT_HIT))
                 p->result = f;
 
         unit_log_result(UNIT(p), p->result == PATH_SUCCESS, path_result_to_string(p->result));

src/core/service.c

@@ -2115,7 +2115,7 @@ static void service_enter_dead(Service *s, ServiceResult f, bool allow_restart)
         if (unit_stop_pending(UNIT(s)))
                 allow_restart = false;
 
-        if (s->result == SERVICE_SUCCESS)
+        if (s->result == SERVICE_SUCCESS || f == SERVICE_FAILURE_START_LIMIT_HIT)
                 s->result = f;
 
         if (s->result == SERVICE_SUCCESS) {

src/core/socket.c

@@ -2116,7 +2116,7 @@ static int socket_chown(Socket *s, PidRef *ret_pid) {
 static void socket_enter_dead(Socket *s, SocketResult f) {
         assert(s);
 
-        if (s->result == SOCKET_SUCCESS)
+        if (s->result == SOCKET_SUCCESS || IN_SET(f, SOCKET_FAILURE_SERVICE_START_LIMIT_HIT, SOCKET_FAILURE_START_LIMIT_HIT))
                 s->result = f;
 
         if (s->result == SOCKET_SUCCESS)

src/core/swap.c

@@ -668,7 +668,7 @@ static int swap_spawn(Swap *s, ExecCommand *c, PidRef *ret_pid) {
 static void swap_enter_dead(Swap *s, SwapResult f) {
         assert(s);
 
-        if (s->result == SWAP_SUCCESS)
+        if (s->result == SWAP_SUCCESS || f == SWAP_FAILURE_START_LIMIT_HIT)
                 s->result = f;
 
         unit_log_result(UNIT(s), s->result == SWAP_SUCCESS, swap_result_to_string(s->result));

src/core/timer.c

@@ -324,7 +324,7 @@ static int timer_coldplug(Unit *u) {
 static void timer_enter_dead(Timer *t, TimerResult f) {
         assert(t);
 
-        if (t->result == TIMER_SUCCESS)
+        if (t->result == TIMER_SUCCESS || f == TIMER_FAILURE_START_LIMIT_HIT)
                 t->result = f;
 
         unit_log_result(UNIT(t), t->result == TIMER_SUCCESS, timer_result_to_string(t->result));

test/units/TEST-07-PID1.issue-3166.sh

@@ -14,3 +14,4 @@ while [[ "$active_state" == "activating" || "$active_state" =~ ^(in)?active$ ]];
 done
 systemctl is-failed issue3166-fail-on-restart.service || exit 1
 [[ "$(systemctl show --value --property NRestarts issue3166-fail-on-restart.service)" -le 3 ]] || exit 1
+[[ "$(systemctl show --value --property Result issue3166-fail-on-restart.service)" = "start-limit-hit" ]] || exit 1