AWS getobject + set premission while saving

I am working on AWS EC2 Ubuntu machine with AWS PHP SDK V2.8 and cakephp V2.3. I am trying to download the object from AWS S3 to my AWS Server. It is working fine just a issue is How can I set permission 644 to 777 of the file.

Here is my code.

        $saveAs = "/var/www/html/app/webroot/files/image/" . $result[$type][0]['id'] . "/" . $result[$type][0]['attachment'];
        $key = "files/image/" . $result[$type][0]['id'] . "/" . $result[$type][0]['attachment'];
        $result = $this->Amazon->S3->getObject(array(
            'Bucket' => 'mytest.sample',
            // 'Key' => 'avtar-auth_test_latest5.png',
            'Key' => $key,
            'version' => 'latest',
            'SaveAs' => $saveAs
        ));

I also tried

   $saveAs = "/var/www/html/app/webroot/files/image/" . $result[$type][0]['id'] . "/" . $result[$type][0]['attachment'];
    $key = "files/image/" . $result[$type][0]['id'] . "/" . $result[$type][0]['attachment'];
    $result = $this->Amazon->S3->getObject(array(
        'Bucket' => 'mytest.sample',
        // 'Key' => 'avtar-auth_test_latest5.png',
        'Key' => $key,
        'version' => 'latest',
        'SaveAs' => chmod($saveAs,'0777')
    ));