Checks if an uploaded file is a .zip one.

isZip.php

<?php
function isZip(string $tmp, string $name)
{
    $extension = pathinfo($name, PATHINFO_EXTENSION);
    $finfo = finfo_open(FILEINFO_MIME_TYPE);
    $type = finfo_file($finfo, $tmp);

    return $type === 'application/zip' && $extension === 'zip';
}