(emacs_root_dir): New function.

src/ChangeLog

 2001-12-19  Eli Zaretskii  <eliz@is.elta.co.il>
+	* w32.c (emacs_root_dir): New function.
+
+	* msdos.c (emacs_root_dir): New function.
+
+	* fileio.c (Fexpand_file_name) [DOS_NT]: Use the root directory
+	of the current drive as the fallback for default_directory.
+
 	* dired.c (file_name_completion): Run the elements of
 	completion-ignored-extensions through ENCODE_FILE.

src/msdos.c

@@ -38,6 +38,7 @@ Boston, MA 02111-1307, USA.  */
 #include <string.h>	 /* for bzero and string functions */
 #include <sys/stat.h>    /* for _fixpath */
 #include <unistd.h>	 /* for chdir, dup, dup2, etc. */
+#include <dir.h>	 /* for getdisk */
 #if __DJGPP__ >= 2
 #include <fcntl.h>
 #include <io.h>		 /* for setmode */
@@ -4118,6 +4119,16 @@ getdefdir (drive, dst)
   return 1;
 }
 
+char *
+emacs_root_dir (void)
+{
+  static char root_dir[4];
+
+  sprintf (root_dir, "%c:/", 'A' + getdisk ());
+  root_dir[0] = tolower (root_dir[0]);
+  return root_dir;
+}
+
 /* Remove all CR's that are followed by a LF.  */
 
 int

src/w32.c

@@ -875,6 +875,21 @@ init_environment (char ** argv)
   init_user_info ();
 }
 
+char *
+emacs_root_dir (void)
+{
+  static char root_dir[FILENAME_MAX];
+  const char *p;
+
+  p = getenv ("emacs_dir");
+  if (p == NULL)
+    abort ();
+  strcpy (root_dir, p);
+  root_dir[parse_root (root_dir, NULL)] = '\0';
+  dostounix_filename (root_dir);
+  return root_dir;
+}
+
 /* We don't have scripts to automatically determine the system configuration
    for Emacs before it's compiled, and we don't want to have to make the
    user enter it, so we define EMACS_CONFIGURATION to invoke this runtime