core: Refuse to run a user instance when the system hasn't been booted with systemd.

Running as a user instance won't work at all if systemd isn't running as system
manager, so refuse to start in that case.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/core/main.c b/src/core/main.c
index f9aba46b5..e094efeb3 100644
--- a/src/core/main.c
+++ b/src/core/main.c
@@ -59,12 +59,13 @@
 #include "hostname-setup.h"
 #include "machine-id-setup.h"
 #include "locale-setup.h"
 #include "hwclock.h"
 #include "selinux-setup.h"
 #include "ima-setup.h"
+#include "sd-daemon.h"
 
 static enum {
         ACTION_RUN,
         ACTION_HELP,
         ACTION_VERSION,
         ACTION_TEST,
@@ -1420,17 +1421,25 @@ int main(int argc, char *argv[]) {
 
         log_parse_environment();
 
         if (parse_argv(argc, argv) < 0)
                 goto finish;
 
-        if (arg_action == ACTION_TEST && geteuid() == 0) {
+        if (arg_action == ACTION_TEST &&
+            geteuid() == 0) {
                 log_error("Don't run test mode as root.");
                 goto finish;
         }
 
+        if (arg_running_as == SYSTEMD_USER &&
+            arg_action == ACTION_RUN &&
+            sd_booted() <= 0) {
+                log_error("Trying to run as user instance, but the system has not been booted with systemd.");
+                goto finish;
+        }
+
         if (arg_running_as == SYSTEMD_SYSTEM &&
             arg_action == ACTION_RUN &&
             running_in_chroot() > 0) {
                 log_error("Cannot be run in a chroot() environment.");
                 goto finish;
         }