[s3] Fix GetObjectTagging when there are no tags

services/s3/itest/s3_test.go

@@ -241,6 +241,34 @@ func TestObjectTagging(t *testing.T) {
 	}
 }
 
+func TestObjectTagging_NoTags(t *testing.T) {
+	ctx := context.Background()
+	client, srv := makeClientServerPair()
+	defer srv.Shutdown(ctx)
+
+	key := "test-key"
+	_, err := client.PutObject(ctx, &s3.PutObjectInput{
+		Bucket: &bucket,
+		Key:    &key,
+		Body:   strings.NewReader("hello"),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tagging, err := client.GetObjectTagging(ctx, &s3.GetObjectTaggingInput{
+		Bucket: &bucket,
+		Key:    &key,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	tags := tagging.TagSet
+	if len(tags) != 0 {
+		t.Fatal("bad tags", tagging.TagSet)
+	}
+}
+
 func TestBucketTagging(t *testing.T) {
 	ctx := context.Background()
 	client, srv := makeClientServerPair()

services/s3/s3.go

@@ -403,15 +403,17 @@ func (s *S3) GetObjectTagging(input GetObjectTaggingInput) (*GetObjectTaggingOut
 	}
 
 	tagging := &GetObjectTaggingOutput{}
-	for _, kv := range strings.Split(object.Tagging, "&") {
-		kv := strings.Split(kv, "=")
-		if len(kv) != 2 {
-			return nil, awserrors.XXX_TODO("invalid tagging")
+	if len(object.Tagging) > 0 {
+		for _, kv := range strings.Split(object.Tagging, "&") {
+			kvs := strings.Split(kv, "=")
+			if len(kvs) != 2 {
+				return nil, awserrors.XXX_TODO(fmt.Sprintf("invalid tagging: '%s', '%s'", kv, object.Tagging))
+			}
+			tagging.TagSet.Tag = append(tagging.TagSet.Tag, APITag{
+				Key:   kvs[0],
+				Value: kvs[1],
+			})
 		}
-		tagging.TagSet.Tag = append(tagging.TagSet.Tag, APITag{
-			Key:   kv[0],
-			Value: kv[1],
-		})
 	}
 	return tagging, nil
 }