Thank you for your checking.

>> BTW, about save-match-data, I used it because of inhibiting changing old
>> match data. Using it is wrong (as the style)?
> 
> save-match-data should only be used where it is really needed, not
> defensively: 99% of the code may destroy the match-date (and could thus
> use save-match-data defensively), whereas less than 1% of the code needs
> the match-data to be saved.
> 

I understand you. I will be carefull about using `save-match-data' from
now on.

>> -          (and (eq cmd0 'quote) (string= cmd1 "mdtm")))
>> +          (and (eq cmd0 'quote) (string-match-p "^\\(mdtm\\|size\\)$" cmd1)))
> 
> I used (member cmd1 '("mdtm" "size")) instead.  The regexp equivalent
> would be "\\`\\(mdtm\\|size\\)\\'".
> 

I also think it is better.

>> +	 (res (prog2
>> +		  (unless ascii-mode
>> +		    (ange-ftp-set-binary-mode host user))
>> +		  (ange-ftp-send-cmd host user (list 'quote "size" name))
>> +		(unless ascii-mode
>> +		  (ange-ftp-set-ascii-mode host user))))
> 
> Now that I look at it: isn't it problematic to set the mode to `ascii'
> here?  If the mode was binary before and we call it with ascii-mode=nil,
> we end up switching to ascii mode unwittingly, don't we?
> 

I read the code of `ange-ftp.el'.
The follows is written...

    In comments:

        By default ange-ftp transfers files in ASCII mode.

    In code:

        (defun ange-ftp-...
            ...
              (unwind-protect
                  (progn
                    ...
                    (if binary
                        (ange-ftp-set-binary-mode host user))
                    ...)
                (if binary
                    (ange-ftp-set-ascii-mode host user)))
            ...)

So, I understood that `ASCII mode' is basic mode.
I wrote after the style.
(In my former patch, I should have used `unwind-protect'.)

But, as you wrote, there is no guarantee that the mode is always ascii.
So, I wrote the mode changing clearly.

> 
>         Stefan
> 

Would you like to check my patch again ?