From 0698d680322eacaf148dcd01c7a350a49c63bf22 Mon Sep 17 00:00:00 2001
From: Aaron Jacobs <jacobsa@google.com>
Date: Fri, 20 Mar 2015 11:49:45 +1100
Subject: [PATCH] flushFS.WriteFile

---
 samples/flushfs/flush_fs.go      | 32 ++++++++++++++++++++++++++++++--
 samples/flushfs/flush_fs_test.go |  9 ++++++---
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/samples/flushfs/flush_fs.go b/samples/flushfs/flush_fs.go
index de77a20..223012c 100644
--- a/samples/flushfs/flush_fs.go
+++ b/samples/flushfs/flush_fs.go
@@ -15,6 +15,7 @@
 package flushfs
 
 import (
+	"fmt"
 	"os"
 	"sync"
 
@@ -40,8 +41,8 @@ const fooID = fuse.RootInodeID + 1
 type flushFS struct {
 	fuseutil.NotImplementedFileSystem
 
-	mu  sync.Mutex
-	foo *os.File // GUARDED_BY(mu)
+	mu          sync.Mutex
+	fooContents []byte // GUARDED_BY(mu)
 }
 
 ////////////////////////////////////////////////////////////////////////
@@ -140,3 +141,30 @@ func (fs *flushFS) OpenFile(
 
 	return
 }
+
+func (fs *flushFS) WriteFile(
+	ctx context.Context,
+	req *fuse.WriteFileRequest) (
+	resp *fuse.WriteFileResponse, err error) {
+	resp = &fuse.WriteFileResponse{}
+
+	fs.mu.Lock()
+	defer fs.mu.Unlock()
+
+	// Ensure that the contents slice is long enough.
+	newLen := int(req.Offset) + len(req.Data)
+	if len(fs.fooContents) < newLen {
+		padding := make([]byte, newLen-len(fs.fooContents))
+		fs.fooContents = append(fs.fooContents, padding...)
+	}
+
+	// Copy in the data.
+	n := copy(fs.fooContents[req.Offset:], req.Data)
+
+	// Sanity check.
+	if n != len(req.Data) {
+		panic(fmt.Sprintf("Unexpected short copy: %v", n))
+	}
+
+	return
+}
diff --git a/samples/flushfs/flush_fs_test.go b/samples/flushfs/flush_fs_test.go
index 9913d0e..0984d21 100644
--- a/samples/flushfs/flush_fs_test.go
+++ b/samples/flushfs/flush_fs_test.go
@@ -75,6 +75,9 @@ func (t *FlushFSTest) SetUp(ti *TestInfo) {
 // Helpers
 ////////////////////////////////////////////////////////////////////////
 
+// Match byte slices equal to the supplied string.
+func byteSliceEq(expected string) Matcher
+
 // Return a copy of the current contents of t.flushes.
 //
 // LOCKS_EXCLUDED(t.mu)
@@ -127,11 +130,11 @@ func (t *FlushFSTest) CloseReports_ReadWrite() {
 	// Seek and read them back.
 	off, err = f.Seek(0, 0)
 	AssertEq(nil, err)
-	AssertEq(4, off)
+	AssertEq(0, off)
 
 	n, err = f.Read(buf)
 	AssertThat(err, AnyOf(nil, io.EOF))
-	AssertEq("taco", buf[:n])
+	AssertEq("taco", string(buf[:n]))
 
 	// At this point, no flushes or fsyncs should have happened.
 	AssertThat(t.getFlushes(), ElementsAre())
@@ -143,7 +146,7 @@ func (t *FlushFSTest) CloseReports_ReadWrite() {
 	AssertEq(nil, err)
 
 	// Now we should have received the flush operation (but still no fsync).
-	ExpectThat(t.getFlushes(), ElementsAre("taco"))
+	ExpectThat(t.getFlushes(), ElementsAre(byteSliceEq("taco")))
 	ExpectThat(t.getFsyncs(), ElementsAre())
 }