PHP - 使用SFTP上传到远程存款

Question

Is there a way to upload files from a FILE INPUT directly to another FTP without using stream_copy_to_stream() ? Actually, I have to do this without uploading the file on local host.

Here is my example code :

/*
    Consider I am getting uploaded files using AJAX
    but thoses files can be reached using $_FILES['file'].
*/

$ssh2 = ssh2_connect("xxxxxx");

if(ssh2_auth_password($ssh2, 'root', 'xxxxx')) {
    $ftp = ssh2_sftp($ssh2);

    $f = fopen("ssh2.sftp://".intval($ftp)."/ftp/images/img.png", 'w');

    /*
        I wonder if it's possible to write directly the content of the
        file inside $f ? Actually, I am uploading PICTURES. Any Idea ?
    */
}