internal/wayland: reimplement connect/bind code

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

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

internal/wayland/conn.go

@@ -1,47 +1,85 @@
 package wayland
 
 import (
+	"errors"
 	"os"
 	"syscall"
+
+	"hakurei.app/container/check"
 )
 
-func bindRawConn(done chan struct{}, rc syscall.RawConn, p, appID, instanceID string) ([2]int, error) {
+// SecurityContext holds resources associated with a Wayland security_context.
+type SecurityContext struct {
+	// Pipe with its write end passed to security-context-v1.
+	closeFds [2]int
+}
+
+// Close releases any resources held by [SecurityContext], and prevents further
+// connections to its associated socket.
+func (sc *SecurityContext) Close() error {
+	if sc == nil {
+		return os.ErrInvalid
+	}
+	return errors.Join(
+		syscall.Close(sc.closeFds[1]),
+		syscall.Close(sc.closeFds[0]),
+	)
+}
+
+// New creates a new security context on the Wayland display at displayPath
+// and associates it with a new socket bound to bindPath.
+//
+// New does not attach a finalizer to the resulting [SecurityContext] struct.
+// The caller is responsible for calling [SecurityContext.Close].
+//
+// A non-nil error unwraps to concrete type [Error].
+func New(displayPath, bindPath *check.Absolute, appID, instanceID string) (*SecurityContext, error) {
+	// ensure bindPath is available
+	if f, err := os.Create(bindPath.String()); err != nil {
+		return nil, &Error{Cause: RHostCreate, Errno: err}
+	} else if err = f.Close(); err != nil {
+		return nil, &Error{Cause: RHostCreate, Errno: err}
+	} else if err = os.Remove(bindPath.String()); err != nil {
+		return nil, &Error{Cause: RHostCreate, Errno: err}
+	}
+
+	if fd, err := syscall.Socket(syscall.AF_UNIX, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0); err != nil {
+		return nil, &Error{RHostSocket, err}
+	} else if err = syscall.Connect(fd, &syscall.SockaddrUnix{Name: displayPath.String()}); err != nil {
+		_ = syscall.Close(fd)
+		return nil, &Error{RHostConnect, err}
+	} else {
+		closeFds, bindErr := bindSecurityContext(fd, bindPath, appID, instanceID)
+		if bindErr != nil {
+			// do not leak the pipe and socket
+			err = errors.Join(bindErr, // already wrapped
+				syscall.Close(closeFds[1]),
+				syscall.Close(closeFds[0]),
+				syscall.Close(fd),
+			)
+		}
+		return &SecurityContext{closeFds}, err
+	}
+}
+
+// bindSecurityContext binds a socket associated to a security context created on serverFd,
+// returning the pipe file descriptors used for security-context-v1 close_fd.
+//
+// A non-nil error unwraps to concrete type [Error].
+func bindSecurityContext(serverFd int, bindPath *check.Absolute, appID, instanceID string) ([2]int, error) {
+	// write end passed to security-context-v1 close_fd
 	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
+	// returned error is already wrapped
+	if err := bindWaylandFd(bindPath.String(), uintptr(serverFd), appID, instanceID, uintptr(closeFds[1])); err != nil {
+		return closeFds, errors.Join(err,
+			syscall.Close(closeFds[1]),
+			syscall.Close(closeFds[0]),
+		)
+	} else {
+		return closeFds, nil
 	}
-
-	return bindWaylandFd(p, fd, appID, instanceID, syncFd)
 }