In php (running in Debian) is it possible to get the number of files inside a zip archive by reading zip file header while the zip file is still being uploaded?

Or are there any linux commands I can run inside php to get the information?

Basically I need to know the number of files inside the zip files before users have finished uploading their zip files so that I know what to expect in advance.

( Is there a chance that file header is not the first chunk of data to be uploaded in any file? )

Thanks