core/service: preserve RuntimeDirectory= even if oneshot service exits

Follow-up for c26948c6da

We only want to get rid of cred mount here, and RuntimeDirectory=
is documented to be retained for SERVICE_EXITED state.

Fixes #35427

src/core/mount.c

@@ -910,7 +910,7 @@ static void mount_enter_dead(Mount *m, MountResult f, bool flush_result) {
 
         m->exec_runtime = exec_runtime_destroy(m->exec_runtime);
 
-        unit_destroy_runtime_data(UNIT(m), &m->exec_context);
+        unit_destroy_runtime_data(UNIT(m), &m->exec_context, /* destroy_runtime_dir = */ true);
 
         unit_unref_uid_gid(UNIT(m), true);
 

src/core/service.c

@@ -1341,7 +1341,7 @@ static void service_set_state(Service *s, ServiceState state) {
                         }
 
                 if (start_only)
-                        unit_destroy_runtime_data(u, &s->exec_context);
+                        unit_destroy_runtime_data(u, &s->exec_context, /* destroy_runtime_dir = */ false);
         }
 
         if (old_state != state)
@@ -2163,7 +2163,7 @@ static void service_enter_dead(Service *s, ServiceResult f, bool allow_restart)
         s->exec_runtime = exec_runtime_destroy(s->exec_runtime);
 
         /* Also, remove the runtime directory */
-        unit_destroy_runtime_data(UNIT(s), &s->exec_context);
+        unit_destroy_runtime_data(UNIT(s), &s->exec_context, /* destroy_runtime_dir = */ true);
 
         /* Also get rid of the fd store, if that's configured. */
         if (s->fd_store_preserve_mode == EXEC_PRESERVE_NO)

src/core/socket.c

@@ -2070,7 +2070,7 @@ static void socket_enter_dead(Socket *s, SocketResult f) {
 
         s->exec_runtime = exec_runtime_destroy(s->exec_runtime);
 
-        unit_destroy_runtime_data(UNIT(s), &s->exec_context);
+        unit_destroy_runtime_data(UNIT(s), &s->exec_context, /* destroy_runtime_dir = */ true);
 
         unit_unref_uid_gid(UNIT(s), true);
 }

src/core/swap.c

@@ -676,7 +676,7 @@ static void swap_enter_dead(Swap *s, SwapResult f) {
 
         s->exec_runtime = exec_runtime_destroy(s->exec_runtime);
 
-        unit_destroy_runtime_data(UNIT(s), &s->exec_context);
+        unit_destroy_runtime_data(UNIT(s), &s->exec_context, /* destroy_runtime_dir = */ true);
 
         unit_unref_uid_gid(UNIT(s), true);
 }

src/core/unit.c

@@ -6148,13 +6148,13 @@ int unit_test_trigger_loaded(Unit *u) {
         return 0;
 }
 
-void unit_destroy_runtime_data(Unit *u, const ExecContext *context) {
+void unit_destroy_runtime_data(Unit *u, const ExecContext *context, bool destroy_runtime_dir) {
         assert(u);
         assert(u->manager);
         assert(context);
 
         /* EXEC_PRESERVE_RESTART is handled via unit_release_resources()! */
-        if (context->runtime_directory_preserve_mode == EXEC_PRESERVE_NO)
+        if (destroy_runtime_dir && context->runtime_directory_preserve_mode == EXEC_PRESERVE_NO)
                 exec_context_destroy_runtime_directory(context, u->manager->prefix[EXEC_DIRECTORY_RUNTIME]);
 
         exec_context_destroy_credentials(context, u->manager->prefix[EXEC_DIRECTORY_RUNTIME], u->id);

src/core/unit.h

@@ -1036,7 +1036,7 @@ int unit_failure_action_exit_status(Unit *u);
 
 int unit_test_trigger_loaded(Unit *u);
 
-void unit_destroy_runtime_data(Unit *u, const ExecContext *context);
+void unit_destroy_runtime_data(Unit *u, const ExecContext *context, bool destroy_runtime_dir);
 int unit_clean(Unit *u, ExecCleanMask mask);
 int unit_can_clean(Unit *u, ExecCleanMask *ret_mask);
 

test/units/TEST-23-UNIT-FILE.RuntimeDirectory.sh

@@ -5,8 +5,6 @@
 set -eux
 set -o pipefail
 
-# Test RuntimeDirectoryPreserve=yes
-
 at_exit() {
     set +e
 
@@ -15,6 +13,21 @@ at_exit() {
 
 trap at_exit EXIT
 
+# RuntimeDirectory= should be preserved for oneshot units if RemainAfterExit=yes
+
+systemd-run --service-type=oneshot --remain-after-exit \
+            -u TEST-23-remain-after-exit.service \
+            -p RuntimeDirectory=TEST-23-remain-after-exit \
+            true
+
+[[ -d /run/TEST-23-remain-after-exit ]]
+
+systemctl stop TEST-23-remain-after-exit.service
+
+[[ ! -e /run/TEST-23-remain-after-exit ]]
+
+# Test RuntimeDirectoryPreserve=yes
+
 systemd-mount -p RuntimeDirectory=hoge -p RuntimeDirectoryPreserve=yes -t tmpfs tmpfs /tmp/aaa
 
 touch /run/hoge/foo