[PATCH v3 1/2] systemd-systemctl-native: capable to call without argument

["kai" <kai.kang@windriver.com>]

From: Kai Kang <kai.kang@windriver.com>

In systemd.bbclass, it will replace criterion command 'type systemctl'
with 'systemctl' without any argument to judge whether command systemctl
is available. The change is to fix install/remove package error in
container when command systemctl exists but not callable.

Make native systemctl wrapper prints help mesages if called without any
argument to follow the update.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
---
 meta/recipes-core/systemd/systemd-systemctl/systemctl | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/meta/recipes-core/systemd/systemd-systemctl/systemctl b/meta/recipes-core/systemd/systemd-systemctl/systemctl
index 990de1ab39..de733e255b 100755
--- a/meta/recipes-core/systemd/systemd-systemctl/systemctl
+++ b/meta/recipes-core/systemd/systemd-systemctl/systemctl
@@ -282,7 +282,7 @@ def main():
         sys.exit("Python 3.4 or greater is required")
 
     parser = argparse.ArgumentParser()
-    parser.add_argument('command', nargs=1, choices=['enable', 'mask',
+    parser.add_argument('command', nargs='?', choices=['enable', 'mask',
                                                      'preset-all'])
     parser.add_argument('service', nargs=argparse.REMAINDER)
     parser.add_argument('--root')
@@ -300,7 +300,11 @@ def main():
         locations.append(BASE_LIBDIR / "systemd")
     locations.append(LIBDIR / "systemd")
 
-    command = args.command[0]
+    command = args.command
+    if not command:
+        parser.print_help()
+        return 0
+
     if command == "mask":
         for service in args.service:
             SystemdUnit(root, service).mask()
-- 
2.17.1