internal/outcome: look up pipewire-pulse path

This is for setting up the pipewire-pulse container in shim, for #29.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/outcome/dispatcher.go

@@ -66,6 +66,8 @@ type syscallDispatcher interface {
 	// lookupGroupId calls [user.LookupGroup] and returns the Gid field of the resulting [user.Group] struct.
 	lookupGroupId(name string) (string, error)
 
+	// lookPath provides exec.LookPath.
+	lookPath(file string) (string, error)
 	// cmdOutput provides the Output method of [exec.Cmd].
 	cmdOutput(cmd *exec.Cmd) ([]byte, error)
 
@@ -140,6 +142,7 @@ func (direct) lookupGroupId(name string) (gid string, err error) {
 	return
 }
 
+func (direct) lookPath(file string) (string, error)    { return exec.LookPath(file) }
 func (direct) cmdOutput(cmd *exec.Cmd) ([]byte, error) { return cmd.Output() }
 
 func (direct) notifyContext(parent context.Context, signals ...os.Signal) (ctx context.Context, stop context.CancelFunc) {

internal/outcome/dispatcher_test.go

@@ -707,6 +707,7 @@ func (panicDispatcher) exit(int)                                            { pa
 func (panicDispatcher) evalSymlinks(string) (string, error)                 { panic("unreachable") }
 func (panicDispatcher) prctl(uintptr, uintptr, uintptr) error               { panic("unreachable") }
 func (panicDispatcher) lookupGroupId(string) (string, error)                { panic("unreachable") }
+func (panicDispatcher) lookPath(string) (string, error)                     { panic("unreachable") }
 func (panicDispatcher) cmdOutput(*exec.Cmd) ([]byte, error)                 { panic("unreachable") }
 func (panicDispatcher) overflowUid(message.Msg) int                         { panic("unreachable") }
 func (panicDispatcher) overflowGid(message.Msg) int                         { panic("unreachable") }

internal/outcome/outcome.go

@@ -70,7 +70,7 @@ type outcomeState struct {
 	// Copied from their respective exported values.
 	mapuid, mapgid *stringPair[int]
 
-	// Copied from [EnvPaths] per-process.
+	// Copied from [env.Paths] per-process.
 	sc hst.Paths
 	*env.Paths
 
@@ -172,6 +172,8 @@ type outcomeStateSys struct {
 
 	// Copied from [hst.Config]. Safe for read by spWaylandOp.toSystem only.
 	directWayland bool
+	// Copied from [hst.Config]. Safe for read by spPipeWireOp.toSystem only.
+	directPipeWire bool
 	// Copied from [hst.Config]. Safe for read by spPulseOp.toSystem only.
 	directPulse bool
 	// Copied header from [hst.Config]. Safe for read by spFilesystemOp.toSystem only.
@@ -187,9 +189,8 @@ type outcomeStateSys struct {
 func (s *outcomeState) newSys(config *hst.Config, sys *system.I) *outcomeStateSys {
 	return &outcomeStateSys{
 		appId: config.ID, et: config.Enablements.Unwrap(),
-		directWayland: config.DirectWayland, directPulse: config.DirectPulse,
-		extraPerms: config.ExtraPerms,
-		sessionBus: config.SessionBus, systemBus: config.SystemBus,
+		directWayland: config.DirectWayland, directPipeWire: config.DirectPipeWire, directPulse: config.DirectPulse,
+		extraPerms: config.ExtraPerms, sessionBus: config.SessionBus, systemBus: config.SystemBus,
 		sys: sys, outcomeState: s,
 	}
 }
@@ -295,7 +296,7 @@ func (state *outcomeStateSys) toSystem() error {
 		// optional via enablements
 		&spWaylandOp{},
 		&spX11Op{},
-		spPipeWireOp{},
+		&spPipeWireOp{},
 		&spPulseOp{},
 		&spDBusOp{},
 

internal/outcome/run_test.go

@@ -883,6 +883,16 @@ func (k *stubNixOS) lookupGroupId(name string) (string, error) {
 	}
 }
 
+func (k *stubNixOS) lookPath(file string) (string, error) {
+	switch file {
+	case "pipewire-pulse":
+		return "/run/current-system/sw/bin/pipewire-pulse", nil
+
+	default:
+		panic(fmt.Sprintf("unexpected file %q", file))
+	}
+}
+
 func (k *stubNixOS) cmdOutput(cmd *exec.Cmd) ([]byte, error) {
 	switch cmd.Path {
 	case "/proc/nonexistent/hsu":

internal/outcome/sppipewire.go

@@ -3,20 +3,33 @@ package outcome
 import (
 	"encoding/gob"
 
+	"hakurei.app/container/check"
 	"hakurei.app/hst"
 	"hakurei.app/internal/pipewire"
 )
 
-func init() { gob.Register(spPipeWireOp{}) }
+const pipewirePulseName = "pipewire-pulse"
+
+func init() { gob.Register(new(spPipeWireOp)) }
 
 // spPipeWireOp exports the PipeWire server to the container via SecurityContext.
 // Runs after spRuntimeOp.
-type spPipeWireOp struct{}
+type spPipeWireOp struct {
+	// Path to pipewire-pulse server. Populated during toSystem if DirectPipeWire is false.
+	CompatServerPath *check.Absolute
+}
 
-func (s spPipeWireOp) toSystem(state *outcomeStateSys) error {
+func (s *spPipeWireOp) toSystem(state *outcomeStateSys) error {
 	if state.et&hst.EPipeWire == 0 {
 		return errNotEnabled
 	}
+	if !state.directPipeWire {
+		if n, err := state.k.lookPath(pipewirePulseName); err != nil {
+			return &hst.AppError{Step: "look up " + pipewirePulseName, Err: err}
+		} else if s.CompatServerPath, err = check.NewAbs(n); err != nil {
+			return err
+		}
+	}
 
 	appId := state.appId
 	if appId == "" {
@@ -27,10 +40,10 @@ func (s spPipeWireOp) toSystem(state *outcomeStateSys) error {
 	return nil
 }
 
-func (s spPipeWireOp) toContainer(state *outcomeStateParams) error {
-	innerPath := state.runtimeDir.Append(pipewire.PW_DEFAULT_REMOTE)
-	state.env[pipewire.Remote] = innerPath.String()
-	state.params.Bind(state.instancePath().Append("pipewire"), innerPath, 0)
+func (s *spPipeWireOp) toContainer(state *outcomeStateParams) error {
+		innerPath := state.runtimeDir.Append(pipewire.PW_DEFAULT_REMOTE)
+		state.env[pipewire.Remote] = innerPath.String()
+		state.params.Bind(state.instancePath().Append("pipewire"), innerPath, 0)
 
 	return nil
 }

internal/outcome/sppipewire_test.go

@@ -16,7 +16,7 @@ func TestSpPipeWireOp(t *testing.T) {
 
 	checkOpBehaviour(t, []opBehaviourTestCase{
 		{"not enabled", func(bool, bool) outcomeOp {
-			return spPipeWireOp{}
+			return new(spPipeWireOp)
 		}, func() *hst.Config {
 			c := hst.Template()
 			*c.Enablements = 0
@@ -24,8 +24,12 @@ func TestSpPipeWireOp(t *testing.T) {
 		}, nil, nil, nil, nil, errNotEnabled, nil, nil, nil, nil, nil},
 
 		{"success", func(bool, bool) outcomeOp {
-			return spPipeWireOp{}
-		}, hst.Template, nil, []stub.Call{}, newI().
+			return new(spPipeWireOp)
+		}, func() *hst.Config {
+			c := hst.Template()
+			c.DirectPipeWire = true
+			return c
+		}, nil, []stub.Call{}, newI().
 			// state.instance
 			Ephemeral(system.Process, m(wantInstancePrefix), 0711).
 			// toSystem