systemctl: give a hint about --force --force when communication with manager fails

The hint is not too explicit, and just refers to the man page, because this
option is slightly dangereous. This was we don't have to discuss the limitation
in the hint itself.

Fixes #4002.

1 files changed, 32 insertions, 27 deletions

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 7ab5559b28..9ca5210dd1 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -3482,6 +3482,8 @@ static int set_exit_code(uint8_t code) {
 static int start_special(int argc, char *argv[], void *userdata) {
         enum action a;
         int r;
+        bool termination_action; /* an action that terminates the manager,
+                                  * can be performed also by signal. */
 
         assert(argv);
 
@@ -3521,40 +3523,43 @@ static int start_special(int argc, char *argv[], void *userdata) {
                         return r;
         }
 
-        if (arg_force >= 2 &&
-            IN_SET(a,
-                   ACTION_HALT,
-                   ACTION_POWEROFF,
-                   ACTION_REBOOT))
+        termination_action = IN_SET(a,
+                                    ACTION_HALT,
+                                    ACTION_POWEROFF,
+                                    ACTION_REBOOT);
+        if (termination_action && arg_force >= 2)
                 return halt_now(a);
 
         if (arg_force >= 1 &&
-            IN_SET(a,
-                   ACTION_HALT,
-                   ACTION_POWEROFF,
-                   ACTION_REBOOT,
-                   ACTION_KEXEC,
-                   ACTION_EXIT))
-                return trivial_method(argc, argv, userdata);
+            (termination_action || IN_SET(ACTION_KEXEC, ACTION_EXIT)))
+                r = trivial_method(argc, argv, userdata);
+        else {
+                /* First try logind, to allow authentication with polkit */
+                if (IN_SET(a,
+                           ACTION_POWEROFF,
+                           ACTION_REBOOT,
+                           ACTION_SUSPEND,
+                           ACTION_HIBERNATE,
+                           ACTION_HYBRID_SLEEP)) {
+
+                        r = logind_reboot(a);
+                        if (r >= 0)
+                                return r;
+                        if (IN_SET(r, -EOPNOTSUPP, -EINPROGRESS))
+                                /* requested operation is not supported or already in progress */
+                                return r;
 
-        /* First try logind, to allow authentication with polkit */
-        if (IN_SET(a,
-                   ACTION_POWEROFF,
-                   ACTION_REBOOT,
-                   ACTION_SUSPEND,
-                   ACTION_HIBERNATE,
-                   ACTION_HYBRID_SLEEP)) {
-                r = logind_reboot(a);
-                if (r >= 0)
-                        return r;
-                if (IN_SET(r, -EOPNOTSUPP, -EINPROGRESS))
-                        /* requested operation is not supported or already in progress */
-                        return r;
+                        /* On all other errors, try low-level operation */
+                }
 
-                /* On all other errors, try low-level operation */
+                r = start_unit(argc, argv, userdata);
         }
 
-        return start_unit(argc, argv, userdata);
+        if (termination_action && arg_force < 2 &&
+            IN_SET(r, -ENOENT, -ETIMEDOUT))
+                log_notice("It is possible to perform action directly, see discussion of --force --force in systemctl(1).");
+
+        return r;
 }
 
 static int start_system_special(int argc, char *argv[], void *userdata) {