clean up setup/launcher code and enable better control over shares

In the past Wayland, X and PulseAudio are shared unconditionally. This can unnecessarily increase attack surface as some of these resources might not be needed at all. This commit moves all environment preparation code to the internal app package and selectively call them based on flags.

An "enablements" bitfield is introduced tracking all enabled shares. This value is registered after successful child process launch and stored in launcher states.

Code responsible for running the child process is isolated to its own app/run file and cleaned up. Launch method selection is also extensively cleaned up.

The internal state/track readLaunchers function now takes uid as an argument. Launcher state is now printed using text/tabwriter and argv is only emitted when verbose.

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

internal/app/setup.go

@@ -4,13 +4,11 @@ import (
 	"errors"
 	"fmt"
 	"os"
-	"os/exec"
 	"os/user"
 	"strconv"
 
 	"git.ophivana.moe/cat/fortify/internal/state"
 	"git.ophivana.moe/cat/fortify/internal/system"
-	"git.ophivana.moe/cat/fortify/internal/util"
 )
 
 type App struct {
@@ -18,78 +16,19 @@ type App struct {
 	env     []string
 	command []string
 
+	enablements state.Enablements
 	*user.User
+
+	// absolutely *no* method of this type is thread-safe
+	// so don't treat it as if it is
 }
 
-func (a *App) Run() {
-	f := a.launchBySudo
-	m, b := false, false
-	switch {
-	case system.MethodFlags[0]: // sudo
-	case system.MethodFlags[1]: // bare
-		m, b = true, true
-	default: // machinectl
-		m, b = true, false
+func (a *App) setEnablement(e state.Enablement) {
+	if a.enablements.Has(e) {
+		panic("enablement " + e.String() + " set twice")
 	}
 
-	var toolPath string
-
-	// dependency checks
-	const sudoFallback = "Falling back to 'sudo', some desktop integration features may not work"
-	if m {
-		if !util.SdBooted() {
-			fmt.Println("This system was not booted through systemd")
-			fmt.Println(sudoFallback)
-		} else if tp, ok := util.Which("machinectl"); !ok {
-			fmt.Println("Did not find 'machinectl' in PATH")
-			fmt.Println(sudoFallback)
-		} else {
-			toolPath = tp
-			f = func() []string { return a.launchByMachineCtl(b) }
-		}
-	} else if tp, ok := util.Which("sudo"); !ok {
-		state.Fatal("Did not find 'sudo' in PATH")
-	} else {
-		toolPath = tp
-	}
-
-	if system.V.Verbose {
-		fmt.Printf("Selected launcher '%s' bare=%t\n", toolPath, b)
-	}
-
-	cmd := exec.Command(toolPath, f()...)
-	cmd.Env = a.env
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	cmd.Dir = system.V.RunDir
-
-	if system.V.Verbose {
-		fmt.Println("Executing:", cmd)
-	}
-
-	if err := cmd.Start(); err != nil {
-		state.Fatal("Error starting process:", err)
-	}
-
-	if err := state.SaveProcess(a.Uid, cmd); err != nil {
-		// process already started, shouldn't be fatal
-		fmt.Println("Error registering process:", err)
-	}
-
-	var r int
-	if err := cmd.Wait(); err != nil {
-		var exitError *exec.ExitError
-		if !errors.As(err, &exitError) {
-			state.Fatal("Error running process:", err)
-		}
-	}
-
-	if system.V.Verbose {
-		fmt.Println("Process exited with exit code", r)
-	}
-	state.BeforeExit()
-	os.Exit(r)
+	a.enablements |= e.Mask()
 }
 
 func New(userName string, args []string) *App {