Prevent crashes on MS-Windows when w32-downcase-file-names is non-nil.

 src/fileio.c (Fsubstitute_in_file_name, Ffile_name_directory)
 (Fexpand_file_name) [DOS_NT]: Pass encoded file name to
 dostounix_filename.  Prevents crashes down the road, because
 dostounix_filename assumes it gets a unibyte string.  Reported by
 Michel de Ruiter <michel@sentient.nl>, see
 http://lists.gnu.org/archive/html/help-emacs-windows/2012-11/msg00017.html

2 files changed, 46 insertions, 9 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index c12eff19ddd..c4f1ee60d84 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2012-11-18  Eli Zaretskii  <eliz@gnu.org>
+
+        * fileio.c (Fsubstitute_in_file_name, Ffile_name_directory)
+        (Fexpand_file_name) [DOS_NT]: Pass encoded file name to
+        dostounix_filename.  Prevents crashes down the road, because
+        dostounix_filename assumes it gets a unibyte string.  Reported by
+        Michel de Ruiter <michel@sentient.nl>, see
+        http://lists.gnu.org/archive/html/help-emacs-windows/2012-11/msg00017.html
+
 2012-11-17  Eli Zaretskii  <eliz@gnu.org>
 
         * w32select.c: Include w32common.h before w32term.h, so that
diff --git a/src/fileio.c b/src/fileio.c
index d47d7dd9e0b..a04eb8ecea1 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -315,6 +315,7 @@ Given a Unix syntax file name, returns a string ending in slash.  */)
   register const char *beg;
 #else
   register char *beg;
+  Lisp_Object tem_fn;
 #endif
   register const char *p;
   Lisp_Object handler;
@@ -374,10 +375,13 @@ Given a Unix syntax file name, returns a string ending in slash.  */)
           p = beg + strlen (beg);
         }
     }
-  dostounix_filename (beg);
-#endif /* DOS_NT */
-
+  tem_fn = ENCODE_FILE (make_specified_string (beg, -1, p - beg,
+                                               STRING_MULTIBYTE (filename)));
+  dostounix_filename (SSDATA (tem_fn));
+  return DECODE_FILE (tem_fn);
+#else  /* DOS_NT */
   return make_specified_string (beg, -1, p - beg, STRING_MULTIBYTE (filename));
+#endif  /* DOS_NT */
 }
 
 DEFUN ("file-name-nondirectory", Ffile_name_nondirectory,
@@ -951,7 +955,18 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
 #ifdef DOS_NT
           /* Make sure directories are all separated with /, but
              avoid allocation of a new string when not required. */
-          dostounix_filename (nm);
+          if (multibyte)
+            {
+              Lisp_Object tem_name = make_specified_string (nm, -1, strlen (nm),
+                                                            multibyte);
+
+              tem_name = ENCODE_FILE (tem_name);
+              dostounix_filename (SSDATA (tem_name));
+              tem_name = DECODE_FILE (tem_name);
+              memcpy (nm, SSDATA (tem_name), SBYTES (tem_name) + 1);
+            }
+          else
+            dostounix_filename (nm);
 #ifdef WINDOWSNT
           if (IS_DIRECTORY_SEP (nm[1]))
             {
@@ -1305,10 +1320,13 @@ filesystem tree, not (expand-file-name ".."  dirname).  */)
         target[0] = '/';
         target[1] = ':';
       }
-    dostounix_filename (target);
-#endif /* DOS_NT */
-
     result = make_specified_string (target, -1, o - target, multibyte);
+    result = ENCODE_FILE (result);
+    dostounix_filename (SSDATA (result));
+    result = DECODE_FILE (result);
+#else  /* !DOS_NT */
+    result = make_specified_string (target, -1, o - target, multibyte);
+#endif /* !DOS_NT */
   }
 
   /* Again look to see if the file name has special constructs in it
@@ -1587,8 +1605,18 @@ those `/' is discarded.  */)
   memcpy (nm, SDATA (filename), SBYTES (filename) + 1);
 
 #ifdef DOS_NT
-  dostounix_filename (nm);
-  substituted = (strcmp (nm, SDATA (filename)) != 0);
+  {
+    Lisp_Object encoded_filename = ENCODE_FILE (filename);
+    Lisp_Object tem_fn;
+
+    dostounix_filename (SDATA (encoded_filename));
+    tem_fn = DECODE_FILE (encoded_filename);
+    nm = alloca (SBYTES (tem_fn) + 1);
+    memcpy (nm, SDATA (tem_fn), SBYTES (tem_fn) + 1);
+    substituted = (memcmp (nm, SDATA (filename), SBYTES (filename)) != 0);
+    if (substituted)
+      filename = tem_fn;
+  }
 #endif
   endp = nm + SBYTES (filename);