PHP Code to check for Zip files which require ZIP64 support to unpack successfully

is_zip_safe.php

<?php

// NOTE: If your goal is to check for maximum compatibility
// rather than ZIP64 specifically, hedge against Zip 
// implementations which use signed integer variables by 
// changing 0xFFFF and 0xFFFFFFFF to 0x7FFF and 0x7FFFFFFF
// and then add a check for which compression algorithm
// each statIndex call says is in use.

function isZipSafe($path) {
    // NOTE: Requires `php-zip` (Debian) or equivalent
    $zipfile = new ZipArchive;
    if ($zipfile->open($path, ZipArchive::RDONLY) === true) {
        $count = $zipfile->count();
        if ($count > 0xFFFF) {
            print("ZIP64 based on number of entries\n");
            $zipfile->close();
            return false;
        } elseif ($count == 0xFFFF) {
            print("May be ZIP64 with a non-Zip64 libzip by number of entries\n");
            $zipfile->close();
            return false;
        }

        for ($i = 0; $i < $count; $i++) {
            $size = $zipfile->statIndex($i)['size'];
            $comp_size = $zipfile->statIndex($i)['comp_size'];
            if ($size > 0xFFFFFFFF || $comp_size > 0xFFFFFFFF) {
                print("ZIP64 based on file size\n");
                $zipfile->close();
                return false;
            } elseif ($size == 0xFFFFFFFF || $comp_size == 0xFFFFFFFF) {
                print("May be ZIP64 with a non-Zip64 libzip by file size\n");
                $zipfile->close();
                return false;
            }
        }
    } else {
        print("Failed to open " . $argv[1] . "\n");
        return false;
    }

    return true;
}

isZipSafe($argv[1]);
?>