From 0d078fcad38cf5a5b54f5f547b5e5a6be4193e4e Mon Sep 17 00:00:00 2001
From: Masaki Yoshida <yoshida.masaki+restartr@gmail.com>
Date: Fri, 9 Dec 2016 11:39:00 +0900
Subject: [PATCH] avoid to decode when item.Value is empty

---
 memd.go      | 10 +++++++++-
 memd_test.go | 27 +++++++++++++++++++++++++--
 2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/memd.go b/memd.go
index e740777..f310c52 100644
--- a/memd.go
+++ b/memd.go
@@ -1,11 +1,16 @@
 package memd
 
 import (
+	"errors"
+	"log"
+
 	"github.com/douban/libmc/golibmc"
 	"github.com/ugorji/go/codec"
-	"log"
 )
 
+// ErrEmptyValue is returned by FromItem when the size of item.Value is zero.
+var ErrEmptyValue = errors.New("cannot decode from empty value")
+
 // Client is wrapper of *golibmc.Client.
 type Client struct {
 	*golibmc.Client
@@ -121,6 +126,9 @@ func (c *Client) ToItem(key string, _val interface{}, exp int64) (*golibmc.Item,
 
 // FromItem ... deserialize item.Value
 func (c *Client) FromItem(item *golibmc.Item, val interface{}) error {
+	if len(item.Value) == 0 {
+		return ErrEmptyValue
+	}
 	return codec.NewDecoderBytes(item.Value, c.serializer).Decode(val)
 }
 
diff --git a/memd_test.go b/memd_test.go
index 123c50f..262cc94 100644
--- a/memd_test.go
+++ b/memd_test.go
@@ -1,11 +1,12 @@
 package memd
 
 import (
-	"github.com/douban/libmc/golibmc"
-	"github.com/ugorji/go/codec"
 	"log"
 	"testing"
 	"time"
+
+	"github.com/douban/libmc/golibmc"
+	"github.com/ugorji/go/codec"
 )
 
 type Result struct {
@@ -125,3 +126,25 @@ func ResultSerializer(t *testing.T) {
 		t.Error("invalid cache")
 	}
 }
+
+func TestResultFromItem(t *testing.T) {
+	c := New(golibmc.SimpleNew([]string{"localhost:11211"}))
+
+	tests := []struct {
+		b   []byte
+		err error
+	}{
+		{[]byte(``), ErrEmptyValue},
+		{[]byte(`{}`), nil},
+		{[]byte(`{"foo":"bar"}`), nil},
+	}
+
+	for _, tt := range tests {
+		item := &golibmc.Item{Value: tt.b}
+		var v map[string]interface{}
+		err := c.FromItem(item, &v)
+		if err != tt.err {
+			t.Errorf("FromItem(%+v, %s) = %#v", item, v, err)
+		}
+	}
+}