Fix: file-watcher bugs (#1897)

* Fix: file-watcher bugs

* Update watcher_linux.go

Co-authored-by: 杨铭哲 <yangmz@weipaitang.com>
Co-authored-by: Asim Aslam <asim@aslam.me>

config/source/file/watcher.go

@@ -39,26 +39,36 @@ func (w *watcher) Next() (*source.ChangeSet, error) {
 	default:
 	}
 
-	// try get the event
-	select {
-	case event, _ := <-w.fw.Events:
-		if event.Op == fsnotify.Rename {
-			// check existence of file, and add watch again
-			_, err := os.Stat(event.Name)
-			if err == nil || os.IsExist(err) {
-				w.fw.Add(event.Name)
+	for {
+		// try get the event
+		select {
+		case event, _ := <-w.fw.Events:
+			if event.Op == fsnotify.Rename {
+				// check existence of file, and add watch again
+				_, err := os.Stat(event.Name)
+				if err == nil || os.IsExist(err) {
+					w.fw.Add(event.Name)
+				}
 			}
-		}
 
-		c, err := w.f.Read()
-		if err != nil {
+			// ARCH: Darwin Kernel Version 18.7.0
+			// ioutil.WriteFile truncates it before writing, but the problem is that
+			// you will receive two events(fsnotify.Chmod and fsnotify.Write).
+			// We can solve this problem by ignoring fsnotify.Chmod event.
+			if event.Op&fsnotify.Write != fsnotify.Write {
+				continue
+			}
+
+			c, err := w.f.Read()
+			if err != nil {
+				return nil, err
+			}
+			return c, nil
+		case err := <-w.fw.Errors:
 			return nil, err
+		case <-w.exit:
+			return nil, source.ErrWatcherStopped
 		}
-		return c, nil
-	case err := <-w.fw.Errors:
-		return nil, err
-	case <-w.exit:
-		return nil, source.ErrWatcherStopped
 	}
 }