使用 PHP 将大文件上传到 FTP

I'm trying to upload large files with php to an ftp server. I can upload small files, but I'm having trouble uploading larger files. I have looked it up and found that I need to set upload_max_filesize and post_max_size, set ftp to passive mode, and set time limit to never. I had no luck with setting the time limit, and what I have now isn't returning any errors, but it is also not uploading the file. If you look at the if (!$upload) { line at the bottom, it should echo something, but it isn't. More importantly, it just isn't working. Any insight as to what is going wrong or what I need to do to make this work? Thank you!

ini_set('upload_max_filesize', '50M');   
ini_set('post_max_size', '50M');  

$conn_id = ftp_connect($ftp_server);

// login with username and password
$login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);

// check connection
if ((!$conn_id) || (!$login_result)) {
        echo "FTP connection has failed!";
        echo "Attempted to connect to $ftp_server for user $ftp_user_name";
        exit;
}

 // turn passive mode on
ftp_pasv($conn_id, true);

if($_FILES['upload_file']['name']!=''){
    $source_file = $_FILES['upload_file']['tmp_name'];
    $destination_file = $_FILES['upload_file']['name']; 

    // upload the file
    $upload = ftp_put($conn_id, $destination_file, $source_file, FTP_BINARY);

    // check upload status
    if (!$upload) {
            echo "FTP upload has failed!<br />";
        } else {
            echo "Uploaded $source_file to $ftp_server as $destination_file<br />";
        }       
}

更新

我发现我无法从 php 页面设置 upload_max_filesize 值；另外，我似乎无法让 .htaccess 工作:如果我有一个 .htaccess 文件，则会导致 HTTP 错误 500.此外，我无权访问 php.ini.