[VOL-4291] Rw-core updates for gRPC migration

Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/coreos/etcd/pkg/ioutil/util.go b/vendor/github.com/coreos/etcd/pkg/ioutil/util.go
new file mode 100644
index 0000000..192ad88
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/pkg/ioutil/util.go
@@ -0,0 +1,43 @@
+// Copyright 2015 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ioutil
+
+import (
+	"io"
+	"os"
+
+	"github.com/coreos/etcd/pkg/fileutil"
+)
+
+// WriteAndSyncFile behaves just like ioutil.WriteFile in the standard library,
+// but calls Sync before closing the file. WriteAndSyncFile guarantees the data
+// is synced if there is no error returned.
+func WriteAndSyncFile(filename string, data []byte, perm os.FileMode) error {
+	f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	n, err := f.Write(data)
+	if err == nil && n < len(data) {
+		err = io.ErrShortWrite
+	}
+	if err == nil {
+		err = fileutil.Fsync(f)
+	}
+	if err1 := f.Close(); err == nil {
+		err = err1
+	}
+	return err
+}