Merge pull request #98 from tilaks/master

Fix data race on kevent buffer.

Not sure why a mutex doesn't work, but this fix will work.

fsnotify_bsd.go

@@ -79,8 +79,6 @@ type Watcher struct {
 	Event           chan *FileEvent     // Events are returned on this channel
 	done            chan bool           // Channel for sending a "quit message" to the reader goroutine
 	isClosed        bool                // Set to true when Close() is first called
-	kbuf            [1]syscall.Kevent_t // An event buffer for Add/Remove watch
-	bufmut          sync.Mutex          // Protects access to kbuf.
 }
 
 // NewWatcher creates and returns a new kevent instance using kqueue(2)
@@ -207,15 +205,13 @@ func (w *Watcher) addWatch(path string, flags uint32) error {
 	w.enFlags[path] = flags
 	w.enmut.Unlock()
 
-	w.bufmut.Lock()
-	watchEntry := &w.kbuf[0]
+	var kbuf [1]syscall.Kevent_t
+	watchEntry := &kbuf[0]
 	watchEntry.Fflags = flags
 	syscall.SetKevent(watchEntry, watchfd, syscall.EVFILT_VNODE, syscall.EV_ADD|syscall.EV_CLEAR)
 	entryFlags := watchEntry.Flags
-	w.bufmut.Unlock()
-
-	wd, errno := syscall.Kevent(w.kq, w.kbuf[:], nil, nil)
-	if wd == -1 {
+	success, errno := syscall.Kevent(w.kq, kbuf[:], nil, nil)
+	if success == -1 {
 		return errno
 	} else if (entryFlags & syscall.EV_ERROR) == syscall.EV_ERROR {
 		return errors.New("kevent add error")
@@ -246,14 +242,14 @@ func (w *Watcher) removeWatch(path string) error {
 	if !ok {
 		return errors.New(fmt.Sprintf("can't remove non-existent kevent watch for: %s", path))
 	}
-	w.bufmut.Lock()
-	watchEntry := &w.kbuf[0]
+	var kbuf [1]syscall.Kevent_t
+	watchEntry := &kbuf[0]
 	syscall.SetKevent(watchEntry, watchfd, syscall.EVFILT_VNODE, syscall.EV_DELETE)
-	success, errno := syscall.Kevent(w.kq, w.kbuf[:], nil, nil)
-	w.bufmut.Unlock()
+	entryFlags := watchEntry.Flags
+	success, errno := syscall.Kevent(w.kq, kbuf[:], nil, nil)
 	if success == -1 {
 		return os.NewSyscallError("kevent_rm_watch", errno)
-	} else if (watchEntry.Flags & syscall.EV_ERROR) == syscall.EV_ERROR {
+	} else if (entryFlags & syscall.EV_ERROR) == syscall.EV_ERROR {
 		return errors.New("kevent rm error")
 	}
 	syscall.Close(watchfd)