app: Only call RegisterClient() if we're root

Otherwise we can't do e.g. `rpm-ostree status`.

Closes: #738

Closes: #739
Approved by: dustymabe

src/app/rpmostree-dbus-helpers.c

@@ -153,11 +153,16 @@ rpmostree_load_sysroot (gchar *sysroot,
   if (sysroot_proxy == NULL)
     return FALSE;
 
-  /* This tells the daemon not to auto-exit as long as we are alive */
-  if (!rpmostree_sysroot_call_register_client_sync (sysroot_proxy,
-                                                    g_variant_builder_end (options_builder),
-                                                    cancellable, error))
-    return FALSE;
+  /* This tells the daemon not to auto-exit as long as we are alive; but we can
+   * only do this as root.
+   */
+  if (getuid () == 0)
+    {
+      if (!rpmostree_sysroot_call_register_client_sync (sysroot_proxy,
+                                                        g_variant_builder_end (options_builder),
+                                                        cancellable, error))
+        return FALSE;
+    }
 
   *out_sysroot_proxy = g_steal_pointer (&sysroot_proxy);
   *out_peer_pid = peer_pid; peer_pid = 0;

tests/vmcheck/test-layering-basic.sh

@@ -49,6 +49,9 @@ if vm_cmd "runuser -u bin rpm-ostree pkg-add foo-1.0"; then
     assert_not_reached "Was able to install a package as non-root!"
 fi
 
+# Assert that we can do status as non-root
+vm_cmd "runuser -u bin rpm-ostree status" >/dev/null
+
 # Be sure an unprivileged user exists
 if vm_rpmostree install test-opt-1.0 2>err.txt; then
     assert_not_reached "Was able to install a package in /opt"