bug#2497: 23.0.91; Fails to read UTF-8 on Win2k

[Eli Zaretskii]

> From: David Engster <deng@randomsample.de>
> Date: Sat, 28 Feb 2009 11:14:16 +0100
> Cc: 2497@emacsbugs.donarmstrong.com
> 
> I once again confirmed that this behaviour can be tracked down to this
> change in detect_coding_charset in coding.c (revision 1.413):
> 
> --- coding.c    7 Feb 2009 10:49:39 -0000       1.412
> +++ coding.c    9 Feb 2009 00:42:37 -0000       1.413
> @@ -5101,7 +5101,7 @@
>    valids = AREF (attrs, coding_attr_charset_valids);
>    name = CODING_ID_NAME (coding->id);
>    if (VECTORP (Vlatin_extra_code_table)
> -      && strcmp ((char *) SDATA (SYMBOL_NAME (name)), "iso-8859-"))
> +      && strcmp ((char *) SDATA (SYMBOL_NAME (name)), "iso-8859-") == 0)
>      check_latin_extra = 1;
>    if (! NILP (CODING_ATTR_ASCII_COMPAT (attrs)))
>      src += head_ascii;
> 
> I'm inclined to say that this change is wrong, since strcmp will only
> return 0 if two strings are exactly equal. In this case though, the
> string "iso-8859-" is compared to "iso-8859-1" (in my case), so it
> returns 1 and therefore check_latin_extra is not set.

You are right.  But in my case, it was not enough to test for
"iso-8859-", as the symbol's name was "iso-latin-1", not "iso-8859-1".

I installed the patch below, that does seem to fix the problem with
the OP's .gnus.el, although I don't know how general that problem is,
nor whether Emacs is capable of distinguishing UTF-8 from Latin-N in
general.


2009-02-28  Eli Zaretskii  <eliz@gnu.org>

        * coding.c (detect_coding_charset): Fix change from 2008-10-21.
        Also, check iso-latin-*, not only iso-8859-*.

Index: src/coding.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/coding.c,v
retrieving revision 1.419
diff -u -r1.419 coding.c
--- src/coding.c        22 Feb 2009 15:48:03 -0000      1.419
+++ src/coding.c        28 Feb 2009 12:01:18 -0000
@@ -5103,7 +5103,10 @@
   valids = AREF (attrs, coding_attr_charset_valids);
   name = CODING_ID_NAME (coding->id);
   if (VECTORP (Vlatin_extra_code_table)
-      && strcmp ((char *) SDATA (SYMBOL_NAME (name)), "iso-8859-") == 0)
+      && (strncmp ((char *) SDATA (SYMBOL_NAME (name)),
+                  "iso-8859-", sizeof ("iso-8859-") - 1) == 0
+         || strncmp ((char *) SDATA (SYMBOL_NAME (name)),
+                     "iso-latin-", sizeof ("iso-latin-") - 1) == 0))
     check_latin_extra = 1;
   if (! NILP (CODING_ATTR_ASCII_COMPAT (attrs)))
     src += head_ascii;