new file mode 100644
--- /dev/null
+++ b/liboctave/oct-env.cc
@@ -0,0 +1,493 @@
+/*
+
+Copyright (C) 1996, 1997 John W. Eaton
+
+This file is part of Octave.
+
+Octave is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+Octave is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+*/
+
+/*
+
+The functions listed below were adapted from a similar functions
+from GNU Bash, the Bourne Again SHell, copyright (C) 1987, 1989, 1991
+Free Software Foundation, Inc.
+
+  octave_env::do_absolute_pathname
+  octave_env::do_base_pathname
+  octave_env::do_chdir
+  octave_env::do_getcwd
+  octave_env::do_make_absolute
+  octave_env::do_polite_directory_format
+  octave_env::pathname_backup
+
+*/ 
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <cerrno>
+#include <cstdlib>
+
+#ifdef HAVE_UNISTD_H
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#include <unistd.h>
+#endif
+
+#ifdef HAVE_PWD_H
+#include <pwd.h>
+#endif
+
+#include "lo-error.h"
+#include "lo-sysdep.h"
+#include "lo-utils.h"
+#include "oct-env.h"
+
+octave_env::octave_env (void)
+  : follow_symbolic_links (true), verbatim_pwd (true),
+    current_directory (), program_name (), program_invocation_name (),
+    user_name (), host_name ()
+{
+  // Get a real value for the current directory.
+  do_getcwd ();
+
+  // Etc.
+  do_get_user_name ();
+
+  do_get_host_name ();
+}
+
+octave_env *octave_env::instance = 0;
+
+bool
+octave_env::instance_ok (void)
+{
+  bool retval = true;
+
+  if (! instance)
+    instance = new octave_env ();
+
+  if (! instance)
+    {
+      (*current_liboctave_error_handler)
+	("unable to create current working directoy object!");
+
+      retval = false;
+    }
+
+  return retval;
+}
+
+string
+octave_env::polite_directory_format (const string& name)
+{
+  return (instance_ok ())
+    ? instance->do_polite_directory_format (name) : string ();
+}
+
+bool
+octave_env::absolute_pathname (const string& s)
+{
+  return (instance_ok ())
+    ? instance->do_absolute_pathname (s) : false;
+}
+
+string
+octave_env::base_pathname (const string& s)
+{
+  return (instance_ok ())
+    ? instance->do_base_pathname (s) : string ();
+}
+
+string
+octave_env::make_absolute (const string& s, const string& dot_path)
+{
+  return (instance_ok ())
+    ? instance->do_make_absolute (s, dot_path) : string ();
+}
+
+string
+octave_env::getcwd ()
+{
+  return (instance_ok ())
+    ? instance->do_getcwd () : string ();
+}
+
+string
+octave_env::get_home_directory ()
+{
+  return (instance_ok ())
+    ? instance->do_get_home_directory () : string ();
+}
+
+string
+octave_env::get_program_name (void)
+{
+  return (instance_ok ())
+    ? instance->program_name : string ();
+}
+
+string
+octave_env::get_program_invocation_name (void)
+{
+  return (instance_ok ())
+    ? instance->program_invocation_name : string ();
+}
+
+void
+octave_env::set_program_name (const string& s)
+{
+  if (instance_ok ())
+    instance->do_set_program_name (s);
+}
+
+string
+octave_env::get_user_name (void)
+{
+  return (instance_ok ())
+    ? instance->do_get_user_name () : string ();
+}
+
+string
+octave_env::get_host_name (void)
+{
+  return (instance_ok ())
+    ? instance->do_get_host_name () : string ();
+}
+
+// XXX FIXME XXX -- this leaves no way to distinguish between a
+// variable that is not set and one that is set to the empty string.
+// Is this a problem?
+
+string
+octave_env::getenv (const string& name)
+{
+  return (instance_ok ())
+    ? instance->do_getenv (name) : string ();
+}
+
+void
+octave_env::putenv (const string& name, const string& value)
+{
+  octave_putenv (name, value);
+}
+
+bool
+octave_env::chdir (const string& newdir)
+{
+  return (instance_ok ())
+    ? instance->do_chdir (newdir) : false;
+}
+
+void
+octave_env::do_set_program_name (const string& s) const
+{
+  program_invocation_name = s;
+
+  size_t pos = program_invocation_name.rfind ('/');
+
+  program_name = (pos == NPOS)
+    ? program_invocation_name : program_invocation_name.substr (pos+1);
+}
+
+// Return a pretty pathname.  If the first part of the pathname is the
+// same as $HOME, then replace that with `~'.
+
+string
+octave_env::do_polite_directory_format (const string& name) const
+{
+  string retval;
+
+  string home_dir = do_get_home_directory ();
+
+  size_t len = home_dir.length ();
+
+  if (len > 1 && home_dir.compare (name, 0, len) == 0
+      && (name.length () == len || name[len] == '/'))
+    {
+      retval = "~";
+      retval.append (name.substr (len));
+    }
+  else
+    retval = name;
+
+  return retval;
+}
+
+// Return 1 if STRING contains an absolute pathname, else 0.
+
+bool
+octave_env::do_absolute_pathname (const string& s) const
+{
+  if (s.empty ())
+    return 0;
+
+  if (s[0] == '/')
+    return true;
+
+  if (s[0] == '.')
+    {
+      if (s[1] == '\0' || s[1] == '/')
+	return true;
+
+      if (s[1] == '.')
+	if (s[2] == '\0' || s[2] == '/')
+	  return true;
+    }
+
+  return false;
+}
+
+// Return the `basename' of the pathname in STRING (the stuff after
+// the last '/').  If STRING is not a full pathname, simply return it.
+
+string
+octave_env::do_base_pathname (const string& s) const
+{
+  if (! do_absolute_pathname (s))
+    return s;
+
+  size_t pos = s.rfind ('/');
+
+  if (pos == NPOS)
+    return s;
+  else
+    return s.substr (pos+1);
+}
+
+// Turn STRING (a pathname) into an absolute pathname, assuming that
+// DOT_PATH contains the symbolic location of '.'.
+
+string
+octave_env::do_make_absolute (const string& s, const string& dot_path) const
+{
+#if defined (__EMX__)
+  if (s.length () > 1 && s[1] == ':')
+    return s;
+#endif
+
+  if (dot_path.empty () || s[0] == '/' || s.empty ())
+    return s;
+
+  string current_path = dot_path;
+
+  if (current_path.empty ())
+    current_path = "./";
+
+  size_t pos = current_path.length () - 1;
+
+  if (current_path[pos] != '/')
+    current_path.append ("/");
+
+  size_t i = 0;
+  size_t slen = s.length ();
+
+  while (i < slen)
+    {
+      if (s[i] == '.')
+	{
+	  if (i + 1 == slen)
+	    return current_path;
+
+	  if (s[i+1] == '/')
+	    {
+	      i += 2;
+	      continue;
+	    }
+
+	  if (s[i+1] == '.' && (i + 2 == slen || s[i+2] == '/'))
+	    {
+	      i += 2;
+
+	      if (i != slen)
+		i++;
+
+	      pathname_backup (current_path, 1);
+
+	      continue;
+	    }
+	}
+
+      size_t tmp = s.find ('/', i);
+
+      if (tmp == NPOS)
+	{
+	  current_path.append (s, i, tmp-i);
+	  break;
+	}
+      else
+	{
+	  current_path.append (s, i, tmp-i+1);
+	  i = tmp + 1;
+	}
+    }
+
+  return current_path;
+}
+
+// Return a consed string which is the current working directory.
+
+string
+octave_env::do_getcwd ()
+{
+  if (! follow_symbolic_links)
+    current_directory = "";
+
+  if (verbatim_pwd || current_directory.empty ())
+    current_directory = ::octave_getcwd ();
+
+  return current_directory;
+}
+
+// This value is not cached because it can change while Octave is
+// running.
+
+string
+octave_env::do_get_home_directory (void) const
+{
+  string hd = do_getenv ("HOME");
+
+  return hd.empty () ? string ("I have no home!") : hd;
+}
+
+string
+octave_env::do_get_user_name (void) const
+{
+  // XXX FIXME XXX -- is it possible for this to change while Octave
+  // is running?
+
+  if (user_name.empty ())
+    {
+      struct passwd *entry = getpwuid (getuid ());
+
+      user_name = entry ? entry->pw_name : "I have no name!";
+    }
+
+  return user_name;
+}
+
+string
+octave_env::do_get_host_name (void) const
+{
+  // XXX FIXME XXX -- is it possible for this to change while Octave
+  // is running?
+
+  if (host_name.empty ())
+    {
+      char hostname[256];
+
+      int status = gethostname (hostname, 255);
+
+      host_name = (status < 0) ? "I have no host!" : hostname;
+    }
+
+  return host_name;
+}
+
+string
+octave_env::do_getenv (const string& name) const
+{
+  char *value = ::getenv (name.c_str ());
+
+  return value ? value : "";
+}
+
+// Do the work of changing to the directory NEWDIR.  Handle symbolic
+// link following, etc.
+
+bool
+octave_env::do_chdir (const string& newdir)
+{
+  bool retval = false;
+
+  string tmp;
+
+  if (follow_symbolic_links)
+    {
+      if (current_directory.empty ())
+	do_getcwd ();
+
+      if (current_directory.empty ())
+	tmp = newdir;
+      else
+	tmp = do_make_absolute (newdir, current_directory);
+
+      // Get rid of trailing `/'.
+
+      size_t len = tmp.length ();
+
+      if (len > 1)
+	{
+	  if (tmp[--len] == '/')
+	    tmp.resize (len);
+	}
+
+      if (! ::octave_chdir (tmp))
+	{
+	  current_directory = tmp;
+	  retval = true;
+	}
+    }
+  else
+    retval = (! ::octave_chdir (newdir));
+
+  return retval;
+}
+
+// Remove the last N directories from PATH.
+
+void
+octave_env::pathname_backup (string& path, int n) const
+{
+  if (path.empty ())
+    return;
+
+  size_t i = path.length () - 1;
+
+  while (n--)
+    {
+      while (path[i] == '/' && i > 0)
+	i--;
+
+      while (path[i] != '/' && i > 0)
+	i--;
+
+      i++;
+    }
+
+  path.resize (i);
+}
+
+void
+octave_env::error (int err_num) const
+{
+  (*current_liboctave_error_handler) ("%s", strerror (err_num));
+}
+
+void
+octave_env::error (const string& s) const
+{
+  (*current_liboctave_error_handler) ("%s", s.c_str ());
+}
+
+/*
+;;; Local Variables: ***
+;;; mode: C++ ***
+;;; End: ***
+*/