internal/params: relocate from package container

This does not make sense as part of the public API, so make it internal.

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

6 files changed, 215 insertions, 39 deletions

diff --git a/internal/outcome/dispatcher.go b/internal/outcome/dispatcher.go
index a3d3dbbc..892e6baf 100644
--- a/internal/outcome/dispatcher.go
+++ b/internal/outcome/dispatcher.go
@@ -17,6 +17,7 @@ import (
 	"hakurei.app/ext"
 	"hakurei.app/internal/dbus"
 	"hakurei.app/internal/info"
+	"hakurei.app/internal/params"
 	"hakurei.app/message"
 )
 
@@ -84,7 +85,7 @@ type syscallDispatcher interface {
 	// setDumpable provides [container.SetDumpable].
 	setDumpable(dumpable uintptr) error
 	// receive provides [container.Receive].
-	receive(key string, e any, fdp *uintptr) (closeFunc func() error, err error)
+	receive(key string, e any, fdp *int) (closeFunc func() error, err error)
 
 	// containerStart provides the Start method of [container.Container].
 	containerStart(z *container.Container) error
@@ -154,8 +155,8 @@ func (direct) prctl(op, arg2, arg3 uintptr) error { return ext.Prctl(op, arg2, a
 func (direct) overflowUid(msg message.Msg) int    { return container.OverflowUid(msg) }
 func (direct) overflowGid(msg message.Msg) int    { return container.OverflowGid(msg) }
 func (direct) setDumpable(dumpable uintptr) error { return ext.SetDumpable(dumpable) }
-func (direct) receive(key string, e any, fdp *uintptr) (func() error, error) {
-	return container.Receive(key, e, fdp)
+func (direct) receive(key string, e any, fdp *int) (func() error, error) {
+	return params.Receive(key, e, fdp)
 }
 
 func (direct) containerStart(z *container.Container) error { return z.Start() }
diff --git a/internal/outcome/dispatcher_test.go b/internal/outcome/dispatcher_test.go
index a099df58..9ae2ba52 100644
--- a/internal/outcome/dispatcher_test.go
+++ b/internal/outcome/dispatcher_test.go
@@ -401,12 +401,12 @@ func (k *kstub) setDumpable(dumpable uintptr) error {
 		stub.CheckArg(k.Stub, "dumpable", dumpable, 0))
 }
 
-func (k *kstub) receive(key string, e any, fdp *uintptr) (closeFunc func() error, err error) {
+func (k *kstub) receive(key string, e any, fdp *int) (closeFunc func() error, err error) {
 	k.Helper()
 	expect := k.Expects("receive")
 	reflect.ValueOf(e).Elem().Set(reflect.ValueOf(expect.Args[1]))
 	if expect.Args[2] != nil {
-		*fdp = expect.Args[2].(uintptr)
+		*fdp = int(expect.Args[2].(uintptr))
 	}
 	return func() error { return k.Expects("closeReceive").Err }, expect.Error(
 		stub.CheckArg(k.Stub, "key", key, 0))
@@ -690,38 +690,38 @@ func (panicMsgContext) Value(any) any               { panic("unreachable") }
 // This type is meant to be embedded in partial syscallDispatcher implementations.
 type panicDispatcher struct{}
 
-func (panicDispatcher) new(func(k syscallDispatcher, msg message.Msg))      { panic("unreachable") }
-func (panicDispatcher) getppid() int                                        { panic("unreachable") }
-func (panicDispatcher) getpid() int                                         { panic("unreachable") }
-func (panicDispatcher) getuid() int                                         { panic("unreachable") }
-func (panicDispatcher) getgid() int                                         { panic("unreachable") }
-func (panicDispatcher) lookupEnv(string) (string, bool)                     { panic("unreachable") }
-func (panicDispatcher) pipe() (*os.File, *os.File, error)                   { panic("unreachable") }
-func (panicDispatcher) stat(string) (os.FileInfo, error)                    { panic("unreachable") }
-func (panicDispatcher) open(string) (osFile, error)                         { panic("unreachable") }
-func (panicDispatcher) readdir(string) ([]os.DirEntry, error)               { panic("unreachable") }
-func (panicDispatcher) tempdir() string                                     { panic("unreachable") }
-func (panicDispatcher) mkdir(string, os.FileMode) error                     { panic("unreachable") }
-func (panicDispatcher) removeAll(string) error                              { panic("unreachable") }
-func (panicDispatcher) exit(int)                                            { panic("unreachable") }
-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") }
-func (panicDispatcher) setDumpable(uintptr) error                           { panic("unreachable") }
-func (panicDispatcher) receive(string, any, *uintptr) (func() error, error) { panic("unreachable") }
-func (panicDispatcher) containerStart(*container.Container) error           { panic("unreachable") }
-func (panicDispatcher) containerServe(*container.Container) error           { panic("unreachable") }
-func (panicDispatcher) containerWait(*container.Container) error            { panic("unreachable") }
-func (panicDispatcher) mustHsuPath() *check.Absolute                        { panic("unreachable") }
-func (panicDispatcher) dbusAddress() (string, string)                       { panic("unreachable") }
-func (panicDispatcher) setupContSignal(int) (io.ReadCloser, func(), error)  { panic("unreachable") }
-func (panicDispatcher) getMsg() message.Msg                                 { panic("unreachable") }
-func (panicDispatcher) fatal(...any)                                        { panic("unreachable") }
-func (panicDispatcher) fatalf(string, ...any)                               { panic("unreachable") }
+func (panicDispatcher) new(func(k syscallDispatcher, msg message.Msg))     { panic("unreachable") }
+func (panicDispatcher) getppid() int                                       { panic("unreachable") }
+func (panicDispatcher) getpid() int                                        { panic("unreachable") }
+func (panicDispatcher) getuid() int                                        { panic("unreachable") }
+func (panicDispatcher) getgid() int                                        { panic("unreachable") }
+func (panicDispatcher) lookupEnv(string) (string, bool)                    { panic("unreachable") }
+func (panicDispatcher) pipe() (*os.File, *os.File, error)                  { panic("unreachable") }
+func (panicDispatcher) stat(string) (os.FileInfo, error)                   { panic("unreachable") }
+func (panicDispatcher) open(string) (osFile, error)                        { panic("unreachable") }
+func (panicDispatcher) readdir(string) ([]os.DirEntry, error)              { panic("unreachable") }
+func (panicDispatcher) tempdir() string                                    { panic("unreachable") }
+func (panicDispatcher) mkdir(string, os.FileMode) error                    { panic("unreachable") }
+func (panicDispatcher) removeAll(string) error                             { panic("unreachable") }
+func (panicDispatcher) exit(int)                                           { panic("unreachable") }
+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") }
+func (panicDispatcher) setDumpable(uintptr) error                          { panic("unreachable") }
+func (panicDispatcher) receive(string, any, *int) (func() error, error)    { panic("unreachable") }
+func (panicDispatcher) containerStart(*container.Container) error          { panic("unreachable") }
+func (panicDispatcher) containerServe(*container.Container) error          { panic("unreachable") }
+func (panicDispatcher) containerWait(*container.Container) error           { panic("unreachable") }
+func (panicDispatcher) mustHsuPath() *check.Absolute                       { panic("unreachable") }
+func (panicDispatcher) dbusAddress() (string, string)                      { panic("unreachable") }
+func (panicDispatcher) setupContSignal(int) (io.ReadCloser, func(), error) { panic("unreachable") }
+func (panicDispatcher) getMsg() message.Msg                                { panic("unreachable") }
+func (panicDispatcher) fatal(...any)                                       { panic("unreachable") }
+func (panicDispatcher) fatalf(string, ...any)                              { panic("unreachable") }
 
 func (panicDispatcher) notifyContext(context.Context, ...os.Signal) (context.Context, context.CancelFunc) {
 	panic("unreachable")
diff --git a/internal/outcome/shim.go b/internal/outcome/shim.go
index d2706c8b..b2074928 100644
--- a/internal/outcome/shim.go
+++ b/internal/outcome/shim.go
@@ -20,6 +20,7 @@ import (
 	"hakurei.app/ext"
 	"hakurei.app/fhs"
 	"hakurei.app/hst"
+	"hakurei.app/internal/params"
 	"hakurei.app/internal/pipewire"
 	"hakurei.app/message"
 )
@@ -197,7 +198,7 @@ func shimEntrypoint(k syscallDispatcher) {
 		if errors.Is(err, syscall.EBADF) {
 			k.fatal("invalid config descriptor")
 		}
-		if errors.Is(err, container.ErrReceiveEnv) {
+		if errors.Is(err, params.ErrReceiveEnv) {
 			k.fatal(shimEnv + " not set")
 		}
 
diff --git a/internal/outcome/shim_test.go b/internal/outcome/shim_test.go
index 08f037da..6d9a9f3d 100644
--- a/internal/outcome/shim_test.go
+++ b/internal/outcome/shim_test.go
@@ -16,6 +16,7 @@ import (
 	"hakurei.app/fhs"
 	"hakurei.app/hst"
 	"hakurei.app/internal/env"
+	"hakurei.app/internal/params"
 	"hakurei.app/internal/stub"
 )
 
@@ -172,7 +173,7 @@ func TestShimEntrypoint(t *testing.T) {
 			call("setDumpable", stub.ExpectArgs{uintptr(ext.SUID_DUMP_DISABLE)}, nil, nil),
 			call("getppid", stub.ExpectArgs{}, 0xbad, nil),
 			call("setupContSignal", stub.ExpectArgs{0xbad}, 0, nil),
-			call("receive", stub.ExpectArgs{"HAKUREI_SHIM", outcomeState{}, nil}, nil, container.ErrReceiveEnv),
+			call("receive", stub.ExpectArgs{"HAKUREI_SHIM", outcomeState{}, nil}, nil, params.ErrReceiveEnv),
 			call("fatal", stub.ExpectArgs{[]any{"HAKUREI_SHIM not set"}}, nil, nil),
 
 			// deferred
diff --git a/internal/params/params.go b/internal/params/params.go
new file mode 100644
index 00000000..6f1962af
--- /dev/null
+++ b/internal/params/params.go
@@ -0,0 +1,42 @@
+// Package params provides helpers for receiving setup payload from parent.
+package params
+
+import (
+	"encoding/gob"
+	"errors"
+	"os"
+	"strconv"
+	"syscall"
+)
+
+// ErrReceiveEnv is returned by [Receive] if setup fd is not present in environment.
+var ErrReceiveEnv = errors.New("environment variable not set")
+
+// Receive retrieves setup fd from the environment and receives params.
+//
+// The file descriptor written to the value pointed to by fdp must not be passed
+// to any system calls. It is made available for ordering file descriptor only.
+func Receive(key string, v any, fdp *int) (func() error, error) {
+	var setup *os.File
+
+	if s, ok := os.LookupEnv(key); !ok {
+		return nil, ErrReceiveEnv
+	} else {
+		if fd, err := strconv.Atoi(s); err != nil {
+			if _err := errors.Unwrap(err); _err != nil {
+				err = _err
+			}
+			return nil, err
+		} else {
+			setup = os.NewFile(uintptr(fd), "setup")
+			if setup == nil {
+				return nil, syscall.EDOM
+			}
+			if fdp != nil {
+				*fdp = fd
+			}
+		}
+	}
+
+	return setup.Close, gob.NewDecoder(setup).Decode(v)
+}
diff --git a/internal/params/params_test.go b/internal/params/params_test.go
new file mode 100644
index 00000000..86c165b8
--- /dev/null
+++ b/internal/params/params_test.go
@@ -0,0 +1,131 @@
+package params_test
+
+import (
+	"encoding/gob"
+	"errors"
+	"os"
+	"slices"
+	"strconv"
+	"syscall"
+	"testing"
+
+	"hakurei.app/internal/params"
+)
+
+func TestSetupReceive(t *testing.T) {
+	t.Run("not set", func(t *testing.T) {
+		const key = "TEST_ENV_NOT_SET"
+		{
+			v, ok := os.LookupEnv(key)
+			t.Cleanup(func() {
+				if ok {
+					if err := os.Setenv(key, v); err != nil {
+						t.Fatalf("Setenv: error = %v", err)
+					}
+				} else {
+					if err := os.Unsetenv(key); err != nil {
+						t.Fatalf("Unsetenv: error = %v", err)
+					}
+				}
+			})
+		}
+
+		if _, err := params.Receive(key, nil, nil); !errors.Is(err, params.ErrReceiveEnv) {
+			t.Errorf("Receive: error = %v, want %v", err, params.ErrReceiveEnv)
+		}
+	})
+
+	t.Run("format", func(t *testing.T) {
+		const key = "TEST_ENV_FORMAT"
+		t.Setenv(key, "")
+
+		if _, err := params.Receive(key, nil, nil); !errors.Is(err, strconv.ErrSyntax) {
+			t.Errorf("Receive: error = %v, want %v", err, strconv.ErrSyntax)
+		}
+	})
+
+	t.Run("range", func(t *testing.T) {
+		const key = "TEST_ENV_RANGE"
+		t.Setenv(key, "-1")
+
+		if _, err := params.Receive(key, nil, nil); !errors.Is(err, syscall.EDOM) {
+			t.Errorf("Receive: error = %v, want %v", err, syscall.EDOM)
+		}
+	})
+
+	t.Run("setup receive", func(t *testing.T) {
+		check := func(t *testing.T, useNilFdp bool) {
+			const key = "TEST_SETUP_RECEIVE"
+			payload := []uint64{syscall.MS_MGC_VAL, syscall.MS_MGC_MSK, syscall.MS_ASYNC, syscall.MS_ACTIVE}
+
+			encoderDone := make(chan error, 1)
+			extraFiles := make([]*os.File, 0, 1)
+			if r, w, err := os.Pipe(); err != nil {
+				t.Fatalf("Setup: error = %v", err)
+			} else {
+				t.Cleanup(func() {
+					if err = errors.Join(r.Close(), w.Close()); err != nil {
+						t.Fatal(err)
+					}
+				})
+
+				extraFiles = append(extraFiles, r)
+				if deadline, ok := t.Deadline(); ok {
+					if err = w.SetDeadline(deadline); err != nil {
+						t.Fatal(err)
+					}
+				}
+				go func() { encoderDone <- gob.NewEncoder(w).Encode(payload) }()
+			}
+
+			if len(extraFiles) != 1 {
+				t.Fatalf("extraFiles: len = %v, want 1", len(extraFiles))
+			}
+
+			var dupFd int
+			if fd, err := syscall.Dup(int(extraFiles[0].Fd())); err != nil {
+				t.Fatalf("Dup: error = %v", err)
+			} else {
+				syscall.CloseOnExec(fd)
+				dupFd = fd
+				t.Setenv(key, strconv.Itoa(fd))
+			}
+
+			var (
+				gotPayload []uint64
+				fdp        *int
+			)
+			if !useNilFdp {
+				fdp = new(int)
+			}
+			var closeFile func() error
+			if f, err := params.Receive(key, &gotPayload, fdp); err != nil {
+				t.Fatalf("Receive: error = %v", err)
+			} else {
+				closeFile = f
+
+				if !slices.Equal(payload, gotPayload) {
+					t.Errorf("Receive: %#v, want %#v", gotPayload, payload)
+				}
+			}
+			if !useNilFdp {
+				if *fdp != dupFd {
+					t.Errorf("Fd: %d, want %d", *fdp, dupFd)
+				}
+			}
+
+			if err := <-encoderDone; err != nil {
+				t.Errorf("Encode: error = %v", err)
+			}
+
+			if closeFile != nil {
+				if err := closeFile(); err != nil {
+					t.Errorf("Close: error = %v", err)
+				}
+			}
+		}
+
+		t.Run("fp", func(t *testing.T) { check(t, false) })
+		t.Run("nil", func(t *testing.T) { check(t, true) })
+	})
+}