From e54aac2c6a0e639c31cbfe95944a1e9c01c05606 Mon Sep 17 00:00:00 2001
From: Jamie Wilkinson <jaq@spacepants.org>
Date: Sun, 22 Mar 2015 11:24:08 +1100
Subject: [PATCH] Apply locking in InMemoryFile

---
 README.md  |  1 +
 fs_test.go | 21 +++++++++++++++++++++
 memfile.go | 14 +++++++++++++-
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index e7d93b2..256dffe 100644
--- a/README.md
+++ b/README.md
@@ -166,6 +166,7 @@ Any Afero FileSystem can be used as an httpFs.
 Names in no particular order:
 
 * [spf13](https://github.com/spf13)
+* [jaqx0r](https://github.com/jaqx0r)
 
 ## License
 
diff --git a/fs_test.go b/fs_test.go
index 4fe6afe..225100e 100644
--- a/fs_test.go
+++ b/fs_test.go
@@ -69,6 +69,27 @@ func TestRead0(t *testing.T) {
 	}
 }
 
+func TestMemFileRead(t *testing.T) {
+	f := MemFileCreate("testfile")
+	f.WriteString("abcd")
+	f.Seek(0, 0)
+	b := make([]byte, 8)
+	n, err := f.Read(b)
+	if n != 4 {
+		t.Errorf("didn't read all bytes: %v %v %v", n, err, b)
+	}
+	if err != nil {
+		t.Errorf("err is not nil: %v %v %v", n, err, b)
+	}
+	n, err = f.Read(b)
+	if n != 0 {
+		t.Errorf("read more bytes: %v %v %v", n, err, b)
+	}
+	if err != io.EOF {
+		t.Errorf("error is not EOF: %v %v %v", n, err, b)
+	}
+}
+
 func TestRename(t *testing.T) {
 	for _, fs := range Fss {
 		from, to := testDir+"/renamefrom", testDir+"/renameto"
diff --git a/memfile.go b/memfile.go
index 4815c6b..2e6751f 100644
--- a/memfile.go
+++ b/memfile.go
@@ -18,6 +18,7 @@ import (
 	"bytes"
 	"io"
 	"os"
+	"sync"
 	"sync/atomic"
 )
 
@@ -32,6 +33,7 @@ type MemDir interface {
 }
 
 type InMemoryFile struct {
+	sync.Mutex
 	at      int64
 	name    string
 	data    []byte
@@ -48,13 +50,17 @@ func MemFileCreate(name string) *InMemoryFile {
 
 func (f *InMemoryFile) Open() error {
 	atomic.StoreInt64(&f.at, 0)
+	f.Lock()
 	f.closed = false
+	f.Unlock()
 	return nil
 }
 
 func (f *InMemoryFile) Close() error {
 	atomic.StoreInt64(&f.at, 0)
+	f.Lock()
 	f.closed = true
+	f.Unlock()
 	return nil
 }
 
@@ -102,14 +108,18 @@ func (f *InMemoryFile) Readdirnames(n int) (names []string, err error) {
 }
 
 func (f *InMemoryFile) Read(b []byte) (n int, err error) {
+	f.Lock()
+	defer f.Unlock()
 	if f.closed == true {
 		return 0, ErrFileClosed
 	}
+	if len(b) > 0 && int(f.at) == len(f.data) {
+		return 0, io.EOF
+	}
 	if len(f.data)-int(f.at) >= len(b) {
 		n = len(b)
 	} else {
 		n = len(f.data) - int(f.at)
-		err = io.EOF
 	}
 	copy(b, f.data[f.at:f.at+int64(n)])
 	atomic.AddInt64(&f.at, int64(n))
@@ -155,6 +165,8 @@ func (f *InMemoryFile) Seek(offset int64, whence int) (int64, error) {
 func (f *InMemoryFile) Write(b []byte) (n int, err error) {
 	n = len(b)
 	cur := atomic.LoadInt64(&f.at)
+	f.Lock()
+	defer f.Unlock()
 	diff := cur - int64(len(f.data))
 	var tail []byte
 	if n+int(cur) < len(f.data) {