dbus: add GetUnitProcessesContext to list any unit's running processes

dbus/methods.go

@@ -839,3 +839,38 @@ func (c *Conn) FreezeUnit(ctx context.Context, unit string) error {
 func (c *Conn) ThawUnit(ctx context.Context, unit string) error {
 	return c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.ThawUnit", 0, unit).Store()
 }
+
+type Process struct {
+	Path    string // Where this process exists in the unit/cgroup hierarchy
+	PID     uint64 // The numeric process ID (PID)
+	Command string // The process command and arguments as a string
+}
+
+// GetUnitProcessesContext returns an array with all currently running processes in a unit *including* its child units.
+func (c *Conn) GetUnitProcessesContext(ctx context.Context, unit string) ([]Process, error) {
+	return c.getUnitProcessesInternal(ctx, unit)
+}
+
+func (c *Conn) getUnitProcessesInternal(ctx context.Context, unit string) ([]Process, error) {
+	result := make([][]interface{}, 0)
+	if err := c.sysobj.CallWithContext(ctx, "org.freedesktop.systemd1.Manager.GetUnitProcesses", 0, unit).Store(&result); err != nil {
+		return nil, err
+	}
+
+	resultInterface := make([]interface{}, len(result))
+	for i := range result {
+		resultInterface[i] = result[i]
+	}
+
+	process := make([]Process, len(result))
+	processInterface := make([]interface{}, len(process))
+	for i := range process {
+		processInterface[i] = &process[i]
+	}
+
+	if err := dbus.Store(resultInterface, processInterface...); err != nil {
+		return nil, err
+	}
+
+	return process, nil
+}

dbus/methods_test.go

@@ -22,10 +22,12 @@ import (
 	"path"
 	"path/filepath"
 	"reflect"
+	"strings"
 	"syscall"
 	"testing"
 	"time"
 
+	"github.com/coreos/go-systemd/v22/util"
 	"github.com/godbus/dbus/v5"
 )
 
@@ -1657,3 +1659,41 @@ func TestFreezer(t *testing.T) {
 
 	runStopUnit(t, conn, TrUnitProp{target, nil})
 }
+
+func TestListUnitProcesses(t *testing.T) {
+	target, err := util.GetRunningSlice() // This test should still pass even if the cmd is spawned in a child unit (i.e. session Scope) of the current Slice
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	conn := setupConn(t)
+	defer conn.Close()
+
+	cmd := exec.Command("/bin/sleep", "400")
+	err = cmd.Start()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer cmd.Process.Kill()
+
+	pid := uint64(cmd.Process.Pid)
+
+	ctx := context.Background()
+	processes, err := conn.GetUnitProcessesContext(ctx, target)
+
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	exists := false
+	for _, p := range processes {
+		if p.PID == pid && strings.HasPrefix(p.Command, "/bin/sleep") {
+			exists = true
+			t.Logf("Found %v\n", p)
+		}
+	}
+
+	if !exists {
+		t.Errorf("PID %d ('/bin/sleep 400') not found in current Slice unit's process list", pid)
+	}
+}