systemd-systemctl: fix handling of instance unit files

This fixes handling of units with instance name in theirs filenames such
as `gnome-shell@wayland.service` or `gnome-shell@x11.service`. Such
files cause template file to be ignored (for the specific instance).

Thanks to Markus Volk <f_l_k@t-online.de> for noticing the breakage when
building images with gnome-shell:

| Error: Systemctl preset_all issue in org.gnome.Shell@wayland.service
| WARNING: /home/flk/poky/build/tmp/work/intel_corei7_64-poky-linux/gnome-image/1.0/temp/run.systemd_preset_all.2011511:158 exit 1 from 'systemctl --root="/home/flk/poky/build/tmp/work/intel_corei7_64-poky-linux/gnome-image/1.0/rootfs" --global --preset-mode=enable-only preset-all'

The problem manifested after cdc3b3028f6d71788b5fdd99436f69fbf18f613e
because we enabled preset-all for user units -
org.gnome.Shell@wayland.service is a user service, so prior to that
change the file wasn't processed at all.

The error was triggered because there is no org.gnome.Shell@.service
file. With this patch applied systemctl script looks for instance unit
file and falls back to template unit in case of lack thereof, keeping
the same behavior upstream systemctl does.

(From OE-Core rev: 7eaad7c2a118b3d9db8b694730535afcd3ca985e)

Signed-off-by: Artur Kowalski <arturkow2000@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/meta/recipes-core/systemd/systemd-systemctl/systemctl b/meta/recipes-core/systemd/systemd-systemctl/systemctl
index 81c246a5b2..65e3157859 100755
--- a/meta/recipes-core/systemd/systemd-systemctl/systemctl
+++ b/meta/recipes-core/systemd/systemd-systemctl/systemctl
@@ -224,7 +224,17 @@ class SystemdUnit():
             instance = None
             unit = self.unit
 
-        path = self._path_for_unit(unit)
+        if instance_unit_name is not None:
+            try:
+                # Try first with instance unit name. Systemd allows to create instance unit files
+                # e.g. `gnome-shell@wayland.service` which cause template unit file to be ignored
+                # for the instance for which instance unit file is present. In that case, there may
+                # not be any template file at all.
+                path = self._path_for_unit(instance_unit_name)
+            except SystemdUnitNotFoundError:
+                path = self._path_for_unit(unit)
+        else:
+            path = self._path_for_unit(unit)
 
         if path.is_symlink():
             # ignore aliases