Description:
------------
If CURLOPT_FILE option is specified, and the file is a ftp handler created by fopen, the resulting file on the ftp server is a zero-byte file.

Test script:
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function save($dlPath, $path, &$filename = null) {
    // Allows overwriting of existing files on the remote FTP server
    $stream_options = array('ftp' => array('overwrite' => true));

    // Creates a stream context resource with the defined options
    $stream_context = stream_context_create($stream_options);

    log_msg("[info] Scarico $path ...");
    $headerBuff = tmpfile();
    $fileTarget = fopen($dlPath, 'w', false, $stream_context);
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $path);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_WRITEHEADER, $headerBuff);
    curl_setopt($ch, CURLOPT_FILE, $fileTarget);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10); 
    curl_setopt($ch, CURLOPT_TIMEOUT, 10);
    curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookie.txt');
    curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookie.txt');
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_PROXY, get_tor()); // instrada su proxy SOCKS5 o gateway Tor
    $f = _my_curl_exec($ch); // implementa le peculiarità
    
    rewind($headerBuff);
    $headers = stream_get_contents($headerBuff);
    if(preg_match('/^Content-Disposition: .*filename=("|\')?([^ ]+)("|\')?$/i', $headers, $matches)) {
        $filename = $matches[1];
        log_msg("[info] Nome del file scaricato: $filename ...");
    }

    fclose($fileTarget);
    fclose($headerBuff);
    return $f;
}

Expected result:
----------------
File size greater than zero

Actual result:
--------------
File size is 0 byte