1 files changed, 103 insertions, 17 deletions

diff --git a/uapi_darwin.go b/uapi_darwin.go
index 2850184..69b0e3d 100644
--- a/uapi_darwin.go
+++ b/uapi_darwin.go
@@ -1,12 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
 package main
 
 import (
+	"errors"
 	"fmt"
 	"golang.org/x/sys/unix"
 	"net"
 	"os"
 	"path"
-	"time"
 )
 
 const (
@@ -22,6 +27,8 @@ type UAPIListener struct {
 	listener net.Listener // unix socket listener
 	connNew  chan net.Conn
 	connErr  chan error
+	kqueueFd int
+	keventFd int
 }
 
 func (l *UAPIListener) Accept() (net.Conn, error) {
@@ -37,48 +44,74 @@ func (l *UAPIListener) Accept() (net.Conn, error) {
 }
 
 func (l *UAPIListener) Close() error {
-	return l.listener.Close()
+	err1 := unix.Close(l.kqueueFd)
+	err2 := unix.Close(l.keventFd)
+	err3 := l.listener.Close()
+	if err1 != nil {
+		return err1
+	}
+	if err2 != nil {
+		return err2
+	}
+	return err3
 }
 
 func (l *UAPIListener) Addr() net.Addr {
 	return nil
 }
 
-func NewUAPIListener(name string) (net.Listener, error) {
+func UAPIListen(name string, file *os.File) (net.Listener, error) {
 
-	// check if path exist
+	// wrap file in listener
 
-	err := os.MkdirAll(socketDirectory, 077)
-	if err != nil && !os.IsExist(err) {
+	listener, err := net.FileListener(file)
+	if err != nil {
 		return nil, err
 	}
 
-	// open UNIX socket
+	uapi := &UAPIListener{
+		listener: listener,
+		connNew:  make(chan net.Conn, 1),
+		connErr:  make(chan error, 1),
+	}
 
 	socketPath := path.Join(
 		socketDirectory,
 		fmt.Sprintf(socketName, name),
 	)
 
-	listener, err := net.Listen("unix", socketPath)
+	// watch for deletion of socket
+
+	uapi.kqueueFd, err = unix.Kqueue()
 	if err != nil {
 		return nil, err
 	}
-
-	uapi := &UAPIListener{
-		listener: listener,
-		connNew:  make(chan net.Conn, 1),
-		connErr:  make(chan error, 1),
+	uapi.keventFd, err = unix.Open(socketDirectory, unix.O_EVTONLY, 0)
+	if err != nil {
+		unix.Close(uapi.kqueueFd)
+		return nil, err
 	}
 
-	// watch for deletion of socket
-
 	go func(l *UAPIListener) {
-		for ; ; time.Sleep(time.Second) {
-			if _, err := os.Stat(socketPath); os.IsNotExist(err) {
+		event := unix.Kevent_t{
+			Ident: uint64(uapi.keventFd),
+			Filter: unix.EVFILT_VNODE,
+			Flags: unix.EV_ADD | unix.EV_ENABLE | unix.EV_ONESHOT,
+			Fflags: unix.NOTE_WRITE,
+		}
+		events := make([]unix.Kevent_t, 1)
+		n := 1
+		var kerr error
+		for {
+			// start with lstat to avoid race condition
+			if _, err := os.Lstat(socketPath); os.IsNotExist(err) {
 				l.connErr <- err
 				return
 			}
+			if kerr != nil || n != 1 {
+				return
+			}
+			n, kerr = unix.Kevent(uapi.kqueueFd, []unix.Kevent_t{event}, events, nil)
 		}
 	}(uapi)
 
@@ -97,3 +130,56 @@ func NewUAPIListener(name string) (net.Listener, error) {
 
 	return uapi, nil
 }
+
+func UAPIOpen(name string) (*os.File, error) {
+
+	// check if path exist
+
+	err := os.MkdirAll(socketDirectory, 0600)
+	if err != nil && !os.IsExist(err) {
+		return nil, err
+	}
+
+	// open UNIX socket
+
+	socketPath := path.Join(
+		socketDirectory,
+		fmt.Sprintf(socketName, name),
+	)
+
+	addr, err := net.ResolveUnixAddr("unix", socketPath)
+	if err != nil {
+		return nil, err
+	}
+
+	listener, err := func() (*net.UnixListener, error) {
+
+		// initial connection attempt
+
+		listener, err := net.ListenUnix("unix", addr)
+		if err == nil {
+			return listener, nil
+		}
+
+		// check if socket already active
+
+		_, err = net.Dial("unix", socketPath)
+		if err == nil {
+			return nil, errors.New("unix socket in use")
+		}
+
+		// cleanup & attempt again
+
+		err = os.Remove(socketPath)
+		if err != nil {
+			return nil, err
+		}
+		return net.ListenUnix("unix", addr)
+	}()
+
+	if err != nil {
+		return nil, err
+	}
+
+	return listener.File()
+}