From f57e92b9a5666052e887e87ce0e4bf78a87f1bdd Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Mon, 26 Feb 2018 19:37:58 +0000
Subject: [PATCH] vfs: fix creation of files when truncating #2083

As spotted by @B4dM4n
---
 vfs/read_write.go | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/vfs/read_write.go b/vfs/read_write.go
index ade4375e1..69913ae3d 100644
--- a/vfs/read_write.go
+++ b/vfs/read_write.go
@@ -3,6 +3,7 @@ package vfs
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"runtime"
 	"sync"
@@ -159,9 +160,12 @@ func (fh *RWFileHandle) openPending(truncate bool) (err error) {
 		// Set the size to 0 since we are truncating and flag we need to write it back
 		fh.file.setSize(0)
 		fh.writeCalled = true
-		if fh.flags&os.O_CREATE != 0 && fh.file.exists() {
-			// create and empty file if it exists on the source
-			cacheFileOpenFlags |= os.O_CREATE
+		if fh.flags&os.O_CREATE == 0 && fh.file.exists() {
+			// create an empty file if it exists on the source
+			err = ioutil.WriteFile(fh.osPath, []byte{}, 0600)
+			if err != nil {
+				return errors.Wrap(err, "cache open failed to create zero length file")
+			}
 		}
 		// Windows doesn't seem to deal well with O_TRUNC and
 		// certain access modes so so truncate the file if it