What I actually wanted to do is read zip file and then if it does contain folder then refuse it with some message.
I want user should upload zip file with files only without any directory structure. So I want to read zip file contains and check file structure. I am trying with following code snippet.
$zip = zip_open('/path/to/zipfile');
while($zip_entry = zip_read($zip)){
$filename = zip_entry_name($zip_entry);
//@todo check whether file or folder.
}