Re: 23.0.60; Assuming errstring unibyte is incorrect and leads to Emacs crashes

[Kenichi Handa]

In article <address@hidden>, Chong Yidong <address@hidden> writes:

> Could someone review the patch submitted with bug#778 for correctness?
> I've excerpted part of the bug report below; the full report can be
> viewed at

>  http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=778

> Dmitry Dzhus <address@hidden> wrote:
[...]
> > Looks like the issue may be resolved replacing a SSET&SREF call at
> > `report_file_error' with something multibyte-aware. I've attached a
> > one-line patch which does the job. It makes an assertion that a
> > downcase and uppercase character both occupy the same amount of bytes.
> >
> > Using `Fdowncase' function instead also fixes the problem, but at a
> > cost of slight overhead (the whole string gets processed, not just the
> > first character (this cannot impact performance seriously though, as I
> > believe those `errstring' variables are not processed often)) my patch
> > does not introduce.
> >
> > I've tested the patch with several locales (both problematic and
> > traditional ones) and couldn't spot any regression introduced with
> > this patch.

Unfortunately, downcasing may change character bytes in some
locale (e.g. turkish), and if the first character is
multibyte, "SREF (errstring, 1)" doesn't give the second
character.

So, I just installed the following change.

2008-08-27  Kenichi Handa  <address@hidden>

        * fileio.c (report_file_error): Fix handling of multibyte error
        string.

Index: fileio.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/fileio.c,v
retrieving revision 1.629
retrieving revision 1.630
diff -u -r1.629 -r1.630
--- fileio.c    5 Aug 2008 21:41:14 -0000       1.629
+++ fileio.c    27 Aug 2008 01:11:26 -0000      1.630
@@ -261,8 +261,14 @@
       default:
        /* System error messages are capitalized.  Downcase the initial
           unless it is followed by a slash.  */
-       if (SREF (errstring, 1) != '/')
-         SSET (errstring, 0, DOWNCASE (SREF (errstring, 0)));
+       if (! EQ (Faref (errstring, make_number (1)), make_number ('/')))
+         {
+           int c;
+
+           str = (char *) SDATA (errstring);
+           c = STRING_CHAR (str, 0);
+           Faset (errstring, 0, make_number (DOWNCASE (c)));
+         }
 
        xsignal (Qfile_error,
                 Fcons (build_string (string), Fcons (errstring, data)));

---
Kenichi Handa
address@hidden