From e70bf0ffaac0f076faf028eb4553acce24556e05 Mon Sep 17 00:00:00 2001
From: Ilia Ross <ilia@ross.gdn>
Date: Wed, 30 Sep 2026 00:05:56 +0200
Subject: [PATCH] Add `get_unit_state` to read fresh systemd unit properties

---
 systemd/systemd-lib.pl | 27 +++++++++++++++++++++++++++
 systemd/t/run-tests.t  | 24 ++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/systemd/systemd-lib.pl b/systemd/systemd-lib.pl
index 8cbe8a777..2ca27a756 100644
--- a/systemd/systemd-lib.pl
+++ b/systemd/systemd-lib.pl
@@ -662,6 +662,33 @@ my $out = backquote_logged(
 return (!$?, $out);
 }
 
+=head2 get_unit_state(name)
+
+Returns a fresh hash of LoadState, UnitFileState, ActiveState, SubState and
+MainPID, followed by an error string. Missing units have LoadState not-found;
+command or validation failures return undef and an error. No inventory cache
+is used, so callers can verify a change immediately.
+
+=cut
+sub get_unit_state
+{
+my ($name) = @_;
+return (undef, $text{'systemd_ename'}) if (!valid_unit_name($name));
+my $out = backquote_logged("systemctl show --no-pager ".
+	"--property=LoadState,UnitFileState,ActiveState,SubState,MainPID ".
+	quotemeta($name)." 2>&1 </dev/null");
+my $rv = $?;
+my %state;
+foreach my $line (split(/\r?\n/, $out)) {
+	$state{$1} = $2
+		if ($line =~ /^(LoadState|UnitFileState|ActiveState|SubState|MainPID)=(.*)$/);
+	}
+# systemctl may return a nonzero status for an explicitly missing unit.
+return (undef, $out || "Failed to read systemd unit $name")
+	if (!$state{'LoadState'} || ($rv && $state{'LoadState'} ne 'not-found'));
+return (\%state, undef);
+}
+
 =head2 dependencies_unit(name)
 
 Gets dependency tree output for a systemd unit.
diff --git a/systemd/t/run-tests.t b/systemd/t/run-tests.t
index 8dcae4e32..9472237a9 100644
--- a/systemd/t/run-tests.t
+++ b/systemd/t/run-tests.t
@@ -855,6 +855,30 @@ like(get_unit_root(), qr{^/(etc|usr/lib|lib)/systemd/system$},
     like($out, qr/Start failed/, 'failed start includes diagnostics');
 }
 
+# Readiness needs fresh properties, including idle sockets and missing units.
+{
+    my $reply = "LoadState=loaded\nUnitFileState=enabled\nActiveState=active\nSubState=listening\nMainPID=0\n";
+    my $status = 0;
+    my @commands;
+    local *main::backquote_logged = sub { push @commands, $_[0]; $? = $status; return $reply; };
+    my ($state, $error) = get_unit_state('demo.socket');
+    is($error, undef, 'valid unit state has no error');
+    is($state->{SubState}, 'listening', 'socket readiness is exposed');
+    like($commands[-1], qr/--property=LoadState,UnitFileState,ActiveState,SubState,MainPID/, 'only requested properties are read');
+    $reply = "LoadState=loaded\nUnitFileState=enabled\nActiveState=inactive\n";
+    ($state, $error) = get_unit_state('demo.socket');
+    is($state->{ActiveState}, 'inactive', 'state is not cached');
+    $reply = "LoadState=not-found\nActiveState=inactive\n"; $status = 1024;
+    ($state, $error) = get_unit_state('missing.service');
+    is($state->{LoadState}, 'not-found', 'missing unit is a valid discovery result');
+    $reply = 'Failed to connect to bus';
+    ($state, $error) = get_unit_state('demo.socket');
+    ok(!defined($state), 'bus failure returns no state');
+    like($error, qr/connect to bus/, 'bus error is preserved');
+    ($state, $error) = get_unit_state('bad;unit.service');
+    is($error, 'bad unit name', 'invalid state lookup is rejected');
+}
+
 {
     my @cmds;
     my $reloaded = 0;