Ignore unified paths with no subsystem

paths_test.go

@@ -60,3 +60,27 @@ func TestRootPath(t *testing.T) {
 		t.Errorf("expected / but received %q", p)
 	}
 }
+
+func TestEmptySubsystem(t *testing.T) {
+	const data = `10:devices:/user.slice
+	9:net_cls,net_prio:/
+	8:blkio:/
+	7:freezer:/
+	6:perf_event:/
+	5:cpuset:/
+	4:memory:/
+	3:pids:/user.slice/user-1000.slice/user@1000.service
+	2:cpu,cpuacct:/
+	1:name=systemd:/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service
+	0::/user.slice/user-1000.slice/user@1000.service/gnome-terminal-server.service`
+	r := strings.NewReader(data)
+	paths, err := parseCgroupFromReader(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for subsystem, path := range paths {
+		if subsystem == "" {
+			t.Fatalf("empty subsystem for %q", path)
+		}
+	}
+}

utils.go

@@ -207,7 +207,9 @@ func parseCgroupFromReader(r io.Reader) (map[string]string, error) {
 			return nil, fmt.Errorf("invalid cgroup entry: must contain at least two colons: %v", text)
 		}
 		for _, subs := range strings.Split(parts[1], ",") {
-			cgroups[subs] = parts[2]
+			if subs != "" {
+				cgroups[subs] = parts[2]
+			}
 		}
 	}
 	return cgroups, nil