fix a corruption in Vector<> when adding new items

would happen when vectors are copied and new items is
added in both vectors. we didn't duplicate the underlying
storage when adding items in vectors.

Bug: 6515797
Change-Id: If544c07d96c05821e088d7f2c9b5736f7e306c31

libs/utils/VectorImpl.cpp

@@ -382,8 +382,8 @@ void* VectorImpl::_grow(size_t where, size_t amount)
             }
         }
     } else {
+        void* array = editArrayImpl();
         if (where != mCount) {
-            void* array = editArrayImpl();
             const void* from = reinterpret_cast<const uint8_t *>(array) + where*mItemSize;
             void* to = reinterpret_cast<uint8_t *>(array) + (where+amount)*mItemSize;
             _do_move_forward(to, from, mCount - where);

libs/utils/tests/Android.mk

@@ -9,6 +9,7 @@ test_src_files := \
 	Looper_test.cpp \
 	String8_test.cpp \
 	Unicode_test.cpp \
+	Vector_test.cpp \
 	ZipFileRO_test.cpp
 
 shared_libraries := \

libs/utils/tests/Vector_test.cpp

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Vector_test"
+
+#include <utils/Vector.h>
+#include <cutils/log.h>
+#include <gtest/gtest.h>
+#include <unistd.h>
+
+namespace android {
+
+class VectorTest : public testing::Test {
+protected:
+    virtual void SetUp() {
+    }
+
+    virtual void TearDown() {
+    }
+
+public:
+};
+
+
+TEST_F(VectorTest, CopyOnWrite_CopyAndAddElements) {
+
+    Vector<int> vector;
+    Vector<int> other;
+    vector.setCapacity(8);
+
+    vector.add(1);
+    vector.add(2);
+    vector.add(3);
+
+    EXPECT_EQ(vector.size(), 3);
+
+    // copy the vector
+    other = vector;
+
+    EXPECT_EQ(other.size(), 3);
+
+    // add an element to the first vector
+    vector.add(4);
+
+    // make sure the sizes are correct
+    EXPECT_EQ(vector.size(), 4);
+    EXPECT_EQ(other.size(), 3);
+
+    // add an element to the copy
+    other.add(5);
+
+    // make sure the sizes are correct
+    EXPECT_EQ(vector.size(), 4);
+    EXPECT_EQ(other.size(), 4);
+
+    // make sure the content of both vectors are correct
+    EXPECT_EQ(vector[3], 4);
+    EXPECT_EQ(other[3], 5);
+}
+
+
+} // namespace android