memory leak with Data::fastSet

[JohnCoconut]

cocos2d-x version: current v3 branch

cocos2d-x/cocos/base/CCData.cpp

Lines 127 to 133 in 4afda3a

	void Data::fastSet(unsigned char* bytes, const ssize_t size)
	{
	CCASSERT(size >= 0, "fastSet size should be non-negative");
	//CCASSERT(bytes, "bytes should not be nullptr");
	_bytes = bytes;
	_size = size;
	}

fastSet makes the Data object managing a new memory area in [bytes, bytes + size), but it doesn't releasing the old data it manages. Failing to release the old data causes memory leak, as happens below,

cocos2d-x/cocos/base/CCUserDefault.cpp

Lines 324 to 334 in 4afda3a

	Data ret = defaultValue;
	if (encodedData)
	{
	unsigned char * decodedData = nullptr;
	int decodedDataLen = base64Decode((unsigned char*)encodedData, (unsigned int)strlen(encodedData), &decodedData);
	if (decodedData) {
	ret.fastSet(decodedData, decodedDataLen);
	}
	}

Can be tested with the following example using valgrind

int main(int argc, char **argv)
{
     UserDefault *userDefault = UserDefault::getInstance();
     Data defaultValue;
     unsigned char *someData = (unsigned char*)malloc(100);
     defaultValue.fastSet(someData, 100);
     Data newData = userDefault->getDataForKey("int_data", defaultValue);
}

with the following UserDefault.xml file,

<?xml version="1.0" encoding="UTF-8"?>
<userDefaultRoot>
    <int_data>BQAAAAQAAAADAAAAAgAAAAEAAAAAAAAA</int_data>
    <float_data>AACgQAAAgEAAAEBAAAAAQAAAgD8AAAAA</float_data>
    <double_data>AAAAAAAAFEAAAAAAAAAQQAAAAAAAAAhAAAAAAAAAAEAAAAAAAADwPwAAAAAAAAAA</double_data>
</userDefaultRoot>