bug#44411: 28.0.50; uudecode-decode-region-internal is broken

[Kazuhiro Ito <kzhr@d1.dion.ne.jp>]

> > When I call uudecode-decode-region-internal in multibyte buffer, it
> > fails to decode eight-bit characters.
> 
> What do you mean by "decode eight-bit characters"?

I mean "decode uuencoded raw bytes 128-255 as eight-bit characters".

> How could such "characters" appear in uuencoded email message?

I did not said anything about uuencoded email message.  What do you
mean?

> Can you describe the real-life use case where this happened?

1. Yank below uuencoded string into multibyte buffer.

begin 644 c8c8c8c8.bin
$R,C(R```@
``
end
size 4

2. C-SPC at the beginning of uuencoded text and move point to the end
of uuencoded text.

3. M-x uudecode-decode-region-internal

4. decoded result is broken.  Original data is 4bytes of 0xc8, but
inserted text is "8888".  uudecode-decode-region-external returns
expected result.

> Please show only the changes to fix what you think is a bug.

Here is.

diff --git a/lisp/mail/uudecode.el b/lisp/mail/uudecode.el
index bcbd571b53..81a0a8ae0d 100644
--- a/lisp/mail/uudecode.el
+++ b/lisp/mail/uudecode.el
@@ -151,9 +151,9 @@ uudecode-decode-region-internal
 	      (cond ((= counter 4)
 		     (setq result (cons
 				   (concat
-				    (char-to-string (ash bits -16))
-				    (char-to-string (logand (ash bits -8) 255))
-				    (char-to-string (logand bits 255)))
+				    (unibyte-string (ash bits -16))
+				    (unibyte-string (logand (ash bits -8) 255))
+				    (unibyte-string (logand bits 255)))
 				   result))
 		     (setq bits 0 counter 0))
 		    (t (setq bits (ash bits 6)))))))
@@ -168,12 +168,12 @@ uudecode-decode-region-internal
 	   ((= counter 3)
 	    (setq result (cons
 			  (concat
-			   (char-to-string (logand (ash bits -16) 255))
-			   (char-to-string (logand (ash bits -8) 255)))
+			   (unibyte-string (logand (ash bits -16) 255))
+			   (unibyte-string (logand (ash bits -8) 255)))
 			  result)))
 	   ((= counter 2)
 	    (setq result (cons
-			  (char-to-string (logand (ash bits -10) 255))
+			  (unibyte-string (logand (ash bits -10) 255))
 			  result))))
 	  (skip-chars-forward non-data-chars end))
 	(if file-name
@@ -184,7 +184,7 @@ uudecode-decode-region-internal
 	  (goto-char start)
 	  (if enable-multibyte-characters
 	      (dolist (x (nreverse result))
-                (insert (decode-coding-string x 'binary)))
+                (insert x))
 	    (insert (apply #'concat (nreverse result))))
 	  (delete-region (point) end))))))
 

-- 
Kazuhiro Ito