systemctl: fix silent failure when --root is not found

Some calls to lookup_path_init() were not followed by any log emission.
E.g.:
$ SYSTEMD_LOG_LEVEL=debug systemctl --root=/missing enable unit; echo $?
1

Let's add a helper function and use it in various places.

$ SYSTEMD_LOG_LEVEL=debug build/systemctl --root=/missing enable unit; echo $?
Failed to initialize unit search paths for root directory /missing: No such file or directory
1
$ SYSTEMCTL_SKIP_SYSV=1 build/systemctl --root=/missing enable unit; echo $?
Failed to initialize unit search paths for root directory /missing: No such file or directory
Failed to enable: No such file or directory.
1

The repeated error in the second case is not very nice, but this is a niche
case and I don't think it's worth the trouble to trying to avoid it.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/analyze/analyze-unit-paths.c b/src/analyze/analyze-unit-paths.c
index 32c97b2e52..6fa1527dd6 100644
--- a/src/analyze/analyze-unit-paths.c
+++ b/src/analyze/analyze-unit-paths.c
@@ -9,9 +9,9 @@ int verb_unit_paths(int argc, char *argv[], void *userdata) {
         _cleanup_(lookup_paths_free) LookupPaths paths = {};
         int r;
 
-        r = lookup_paths_init(&paths, arg_scope, 0, NULL);
+        r = lookup_paths_init_or_warn(&paths, arg_scope, 0, NULL);
         if (r < 0)
-                return log_error_errno(r, "lookup_paths_init() failed: %m");
+                return r;
 
         STRV_FOREACH(p, paths.search_path)
                 puts(*p);