Self-downloadable package maker inPHP

packager.php

<?php

/** Create PHP file with self-downloadable content regardless to file-type and server settings
    @var $source Full filname of file to download
    @var $target Path to save self-downloadable package
    @return Package info
*/
function createDownloadablePackage($source, $target) {
    $filename = basename($source);
    $filesize = filesize($source);
    $dest = $target."/cache_".md5(mt_rand()).".php";

    $fp = fopen($source, "r");
    $fo = fopen($dest, "w");
    fwrite($fo, getHeader($filename, $filesize));
    stream_copy_to_stream($fp, $fo);

    $response = [
        'filename' => $filename,
        'filesize' => $filesize,
        'dest' => $dest,
    ];

    return $response;
}

function getHeader($filename, $filesize) {
    $header = "<"."?php " .
        "\$fp = fopen(__FILE__, \"r\");" .
        "\$fo = fopen(\"php://output\", \"w\");" .
        "header(\"Content-Type: application/octet-stream\");" .
        "header(\"Content-Length: $filesize\");" .
        "header(\"Content-Disposition: attachment; filename=\\\"$filename\\\"\");" .
        "fseek(\$fp, __COMPILER_HALT_OFFSET__);" .
        "stream_copy_to_stream(\$fp, \$fo);" .
        "__halt_compiler();";
    return $header;
}