internal/wayland: reimplement connect/bind code

The old implementation is relocated to system/wayland/deprecated.go.

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

system/wayland/deprecated.go

@@ -15,6 +15,9 @@ import (
 	"hakurei.app/internal/wayland"
 )
 
+//go:linkname bindWaylandFd hakurei.app/internal/wayland.bindWaylandFd
+func bindWaylandFd(socketPath string, fd uintptr, appID, instanceID string, syncFd uintptr) error
+
 // Conn represents a connection to the wayland display server.
 //
 // Deprecated: this interface is being replaced.
@@ -60,9 +63,6 @@ func (c *Conn) Close() error {
 	return nil
 }
 
-//go:linkname bindRawConn hakurei.app/internal/wayland.bindRawConn
-func bindRawConn(done chan struct{}, rc syscall.RawConn, p, appID, instanceID string) ([2]int, error)
-
 // Bind binds the new socket to pathname.
 func (c *Conn) Bind(pathname, appID, instanceID string) (*os.File, error) {
 	c.mu.Lock()
@@ -88,6 +88,47 @@ func (c *Conn) Bind(pathname, appID, instanceID string) (*os.File, error) {
 	}
 }
 
+func bindRawConn(done chan struct{}, rc syscall.RawConn, p, appID, instanceID string) ([2]int, error) {
+	var closeFds [2]int
+	if err := syscall.Pipe2(closeFds[0:], syscall.O_CLOEXEC); err != nil {
+		return closeFds, err
+	}
+
+	setupDone := make(chan error, 1) // does not block with c.done
+
+	go func() {
+		if err := rc.Control(func(fd uintptr) {
+			// allow the Bind method to return after setup
+			setupDone <- bind(fd, p, appID, instanceID, uintptr(closeFds[1]))
+			close(setupDone)
+
+			// keep socket alive until done is requested
+			<-done
+		}); err != nil {
+			setupDone <- err
+		}
+
+		// notify Close that rc.Control has returned
+		close(done)
+	}()
+
+	// return write end of the pipe
+	return closeFds, <-setupDone
+}
+
+func bind(fd uintptr, p, appID, instanceID string, syncFd uintptr) error {
+	// ensure p is available
+	if f, err := os.Create(p); err != nil {
+		return err
+	} else if err = f.Close(); err != nil {
+		return err
+	} else if err = os.Remove(p); err != nil {
+		return err
+	}
+
+	return bindWaylandFd(p, fd, appID, instanceID, syncFd)
+}
+
 const (
 	// WaylandDisplay contains the name of the server socket
 	// (https://gitlab.freedesktop.org/wayland/wayland/-/blob/1.23.1/src/wayland-client.c#L1147)