helper: separate pipes from Helper

Upcoming bwrap helper implementation requires two sets of pipes to be managed, fd will also no longer be constant.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

dbus/dbus_test.go

@@ -164,7 +164,7 @@ func TestProxy_Start_Wait_Close_String(t *testing.T) {
 					}
 
 					t.Run("started string of "+id, func(t *testing.T) {
-						wantSubstr := binPath + " --args=3 --fd=4"
+						wantSubstr := binPath + " --args=3"
 						if got := p.String(); !strings.Contains(got, wantSubstr) {
 							t.Errorf("String() = %v, want %v",
 								p.String(), wantSubstr)

dbus/run.go

@@ -3,6 +3,7 @@ package dbus
 import (
 	"errors"
 	"io"
+	"strconv"
 
 	"git.ophivana.moe/cat/fortify/helper"
 )
@@ -18,9 +19,13 @@ func (p *Proxy) Start(ready chan error, output io.Writer) error {
 	}
 
 	h := helper.New(p.seal, p.path,
-		// Helper: Args is always 3 and status if set is always 4.
-		"--args=3",
-		"--fd=4",
+		func(argsFD, statFD int) []string {
+			if statFD == -1 {
+				return []string{"--args=" + strconv.Itoa(argsFD)}
+			} else {
+				return []string{"--args=" + strconv.Itoa(argsFD), "--fd=" + strconv.Itoa(statFD)}
+			}
+		},
 	)
 	// xdg-dbus-proxy does not need to inherit the environment
 	h.Env = []string{}