PHP FTP复制整个目录递归

Question

我需要创建一个php脚本，以便它将其复制到服务器上的文件夹中，并且源目录将是另一台服务器。

我正在尝试：

    function ftp_sync($dir, $conn_id, $url) {

        $remoto_dir = '/web/meusite.site/public_html/uploads/img/'.$url;
        $local_dir  = '../admin/uploads/img/'.$url;

        if ($remoto_dir !== '.') {
            if (ftp_chdir($conn_id, $remoto_dir) === FALSE) {
                echo 'Change dir failed: ' . $remoto_dir . PHP_EOL;
                return;
            }
            if (!(is_dir($remoto_dir))) {
                mkdir($local_dir);
            }
            chdir($remoto_dir);
        }
            $contents = ftp_nlist($conn_id, '.');
            foreach ($contents as $file) {
                if ($file == '.' || $file == '..') {
                    continue;
                }
                if (@ftp_chdir($conn_id, $file)) {
                    ftp_chdir($conn_id, "..");
                    ftp_sync($file, $conn_id, $url);
                } else {
                    ftp_get($conn_id, $local_dir.'/'.$file, $file, FTP_BINARY);
                }
            }
        ftp_chdir($conn_id, '..');
        chdir('..');
    }

调用函数：

    if ($conn_id) {

            ftp_chdir($conn_id,'/web/meusite.site/public_html/uploads/img/'.$url;);
            ftp_sync($conn_id, $itemURL);
            ftp_close($conn_id);

    } else {
        echo 'connection to server failed!';
    }

页面处于永恒加载状态，什么也没发生