From 6bdf70432614ad7609daab8b7e0d6040ce45d76a Mon Sep 17 00:00:00 2001
From: Dylan Ratcliffe <dylanratcliffe@outlook.com>
Date: Mon, 13 Dec 2021 09:19:33 +0000
Subject: [PATCH 1/2] dbus: add ability to query by pid

Allows users to get the unit name by PID. Similar to `systemctl status {pid}`
---
 dbus/methods.go      | 18 ++++++++++++++++++
 dbus/methods_test.go | 16 ++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/dbus/methods.go b/dbus/methods.go
index f577ab37..8ab380d9 100644
--- a/dbus/methods.go
+++ b/dbus/methods.go
@@ -417,6 +417,24 @@ func (c *Conn) listUnitsInternal(f storeFunc) ([]UnitStatus, error) {
 	return status, nil
 }
 
+func (c *Conn) getUnitInternal(f storeFunc) (string, error) {
+	var result dbus.ObjectPath
+
+	err := f(&result)
+
+	// Nothing in this library actually accepts a dbus.ObjectPath, so it's much
+	// more useful as a name
+	name := unitName(result)
+
+	return name, err
+}
+
+// GetUnitByPIDContext returns the unit name for a given PID. The PID must refer
+// to an existing system process
+func (c *Conn) GetUnitByPIDContext(ctx context.Context, pid uint32) (string, error) {
+	return c.getUnitInternal(c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.GetUnitByPID", 0, pid).Store)
+}
+
 // Deprecated: use ListUnitsContext instead.
 func (c *Conn) ListUnits() ([]UnitStatus, error) {
 	return c.ListUnitsContext(context.Background())
diff --git a/dbus/methods_test.go b/dbus/methods_test.go
index 55bc2c9c..d0ba2bf2 100644
--- a/dbus/methods_test.go
+++ b/dbus/methods_test.go
@@ -450,6 +450,22 @@ func TestReloadOrRestartUnit(t *testing.T) {
 	}
 }
 
+// Ensure that GetUnitByPIDContext works.
+func TestGetUnitByPIDContext(t *testing.T) {
+	conn := setupConn(t)
+	defer conn.Close()
+
+	name, err := conn.GetUnitByPIDContext(context.Background(), 1)
+
+	if err != nil {
+		t.Error(err)
+	}
+
+	if name == "" {
+		t.Fatal("name is empty")
+	}
+}
+
 // Ensure that ListUnitsByNames works.
 func TestListUnitsByNames(t *testing.T) {
 	target1 := "systemd-journald.service"

From fd56b7311968ab0add68760d4bd1f7add80fc3f2 Mon Sep 17 00:00:00 2001
From: Dylan Ratcliffe <dylanratcliffe@outlook.com>
Date: Mon, 13 Dec 2021 10:01:25 +0000
Subject: [PATCH 2/2] dbus: add options for name & path

PID-based queries can now return either a name or a path
---
 dbus/methods.go      | 27 ++++++++++++++++-----------
 dbus/methods_test.go | 22 +++++++++++++++++++---
 2 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/dbus/methods.go b/dbus/methods.go
index 8ab380d9..074148cb 100644
--- a/dbus/methods.go
+++ b/dbus/methods.go
@@ -417,22 +417,27 @@ func (c *Conn) listUnitsInternal(f storeFunc) ([]UnitStatus, error) {
 	return status, nil
 }
 
-func (c *Conn) getUnitInternal(f storeFunc) (string, error) {
+// GetUnitByPID returns the unit object path of the unit a process ID
+// belongs to. It takes a UNIX PID and returns the object path. The PID must
+// refer to an existing system process
+func (c *Conn) GetUnitByPID(ctx context.Context, pid uint32) (dbus.ObjectPath, error) {
 	var result dbus.ObjectPath
 
-	err := f(&result)
-
-	// Nothing in this library actually accepts a dbus.ObjectPath, so it's much
-	// more useful as a name
-	name := unitName(result)
+	err := c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.GetUnitByPID", 0, pid).Store(&result)
 
-	return name, err
+	return result, err
 }
 
-// GetUnitByPIDContext returns the unit name for a given PID. The PID must refer
-// to an existing system process
-func (c *Conn) GetUnitByPIDContext(ctx context.Context, pid uint32) (string, error) {
-	return c.getUnitInternal(c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.GetUnitByPID", 0, pid).Store)
+// GetUnitNameByPID returns the name of the unit a process ID belongs to. It
+// takes a UNIX PID and returns the object path. The PID must refer to an
+// existing system process
+func (c *Conn) GetUnitNameByPID(ctx context.Context, pid uint32) (string, error) {
+	path, err := c.GetUnitByPID(ctx, pid)
+	if err != nil {
+		return "", err
+	}
+
+	return unitName(path), nil
 }
 
 // Deprecated: use ListUnitsContext instead.
diff --git a/dbus/methods_test.go b/dbus/methods_test.go
index d0ba2bf2..30cc1324 100644
--- a/dbus/methods_test.go
+++ b/dbus/methods_test.go
@@ -450,12 +450,28 @@ func TestReloadOrRestartUnit(t *testing.T) {
 	}
 }
 
-// Ensure that GetUnitByPIDContext works.
-func TestGetUnitByPIDContext(t *testing.T) {
+// Ensure that GetUnitByPID works.
+func TestGetUnitByPID(t *testing.T) {
 	conn := setupConn(t)
 	defer conn.Close()
 
-	name, err := conn.GetUnitByPIDContext(context.Background(), 1)
+	path, err := conn.GetUnitByPID(context.Background(), 1)
+
+	if err != nil {
+		t.Error(err)
+	}
+
+	if path == "" {
+		t.Fatal("path is empty")
+	}
+}
+
+// Ensure that GetUnitNameByPID works.
+func TestGetUnitNameByPID(t *testing.T) {
+	conn := setupConn(t)
+	defer conn.Close()
+
+	name, err := conn.GetUnitNameByPID(context.Background(), 1)
 
 	if err != nil {
 		t.Error(err)