nspawn: give better message when invoked as non-root without arguments

When invoked as non-root, we would suggest re-running as root without any
further hint. But this immediately spawns a machine from the local directory,
which can be rather surprising. So let's give a better hint.

(In general, I don't think commandline programs should do "significant" things
when invoked without any arguments. In this regard it would be better if
systemd-nspawn would not spawn a machine from the current directory if called
with no arguments and at least "-D ." would be required.)

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index ea5be3f72dadc2505e35cf9f5e004f0425ab45fb..36a26046641195fb8574f964e2eccb5ca626110d 100644 (file)
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -5134,9 +5134,12 @@ static int run(int argc, char *argv[]) {
         if (r <= 0)
                 goto finish;
 
-        r = must_be_root();
-        if (r < 0)
+        if (geteuid() != 0) {
+                r = log_warning_errno(SYNTHETIC_ERRNO(EPERM),
+                                      argc >= 2 ? "Need to be root." :
+                                      "Need to be root (and some arguments are usually required).\nHint: try --help");
                 goto finish;
+        }
 
         r = cant_be_in_netns();
         if (r < 0)