bug#29189: 25.3; Dired does not work with binary filenames

[Eli Zaretskii]

> From: Andreas Schwab <schwab@suse.de>
> Cc: Kenichi Handa <handa@gnu.org>,  vianchielfaura@gmail.com,  
> 29189@debbugs.gnu.org
> Date: Mon, 20 Nov 2017 10:48:09 +0100
> 
> > +         /* Copy raw bytes in their 2-byte forms as single characters.  */
> > +         if (CHAR_BYTE8_HEAD_P (*src) && nbytes > 0)
> > +           {
> > +             c = STRING_CHAR_ADVANCE (src);
> 
> CHAR_BYTE8_HEAD_P and STRING_CHAR_ADVANCE are only valid for multibyte
> strings.  I don't think it makes sense to use them for unibyte strings.

Right you are, thanks.  Updated patch below.

diff --git a/src/coding.c b/src/coding.c
index d790ad0..ac55f87 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -7423,10 +7423,23 @@ decode_coding (struct coding_system *coding)
 
          while (nbytes-- > 0)
            {
-             int c = *src++;
+             int c;
 
-             if (c & 0x80)
-               c = BYTE8_TO_CHAR (c);
+             /* Copy raw bytes in their 2-byte forms from multibyte
+                text as single characters.  */
+             if (coding->src_multibyte
+                 && CHAR_BYTE8_HEAD_P (*src) && nbytes > 0)
+               {
+                 c = STRING_CHAR_ADVANCE (src);
+                 nbytes--;
+               }
+             else
+               {
+                 c = *src++;
+
+                 if (c & 0x80)
+                   c = BYTE8_TO_CHAR (c);
+               }
              coding->charbuf[coding->charbuf_used++] = c;
            }
          produce_chars (coding, Qnil, 1);