Simple function that return total size of files in archive.
May be useful for check for zip bombs.

<?php

function get_zip_originalsize($filename) {
    $size = 0;
    $resource = zip_open($filename);
    while ($dir_resource = zip_read($resource)) {
        $size += zip_entry_filesize($dir_resource);
    }
    zip_close($resource);

    return $size;
}

$size = get_zip_originalsize('file.zip');
echo "original size: $size bytes\n";

?>