/*

Copyright (C) 1993-2012 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 3 of the License, 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, see
<http://www.gnu.org/licenses/>.

*/

// Born February 20, 1992.

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <cassert>
#include <cstdlib>
#include <cstring>
#include <ctime>

#include <iostream>

#include <getopt.h>
#include <sys/types.h>
#include <unistd.h>

#include "cmd-edit.h"
#include "f77-fcn.h"
#include "file-ops.h"
#include "file-stat.h"
#include "lo-error.h"
#include "oct-env.h"
#include "str-vec.h"

#include "builtins.h"
#include "defaults.h"
#include "Cell.h"
#include "defun.h"
#include "display.h"
#include "error.h"
#include "file-io.h"
#include "help.h"
#include "input.h"
#include "lex.h"
#include "load-path.h"
#include "octave.h"
#include "oct-conf.h"
#include "oct-hist.h"
#include "oct-map.h"
#include "oct-mutex.h"
#include "oct-obj.h"
#include "ops.h"
#include "ov.h"
#include "ov-range.h"
#include "toplev.h"
#include "parse.h"
#include "procstream.h"
#include "sighandlers.h"
#include "sysdep.h"
#include "unwind-prot.h"
#include "utils.h"
#include "variables.h"
#include <version.h>

// Kluge.
extern "C" F77_RET_T
F77_FUNC (xerbla, XERBLA) (F77_CONST_CHAR_ARG_DECL,
                           const octave_idx_type&
                           F77_CHAR_ARG_LEN_DECL);

extern void install_builtins (void);

int octave_cmdline_argc;
char **octave_cmdline_argv;
int octave_embedded;

// The command-line options.
static string_vector octave_argv;

// The name used to invoke Octave.
static std::string
octave_program_invocation_name;

// The last component of octave_program_invocation_name.
static std::string octave_program_name;

// TRUE means we read ~/.octaverc and ./.octaverc.
// (--norc; --no-init-file; -f)
static bool read_init_files = true;

// TRUE means we read the site-wide octaverc files.
// (--norc; --no-site-file; -f)
static bool read_site_files = true;

// TRUE means we set the initial path to configured defaults.
// (--no-init-path)
static bool set_initial_path = true;

// TRUE means we don't print the usual startup message.
// (--quiet; --silent; -q)
static bool inhibit_startup_message = false;

// If TRUE, print verbose info in some cases.
// (--verbose; -V)
static bool verbose_flag = false;

// If TRUE, force the GUI to start.
// (--force-gui)
static bool force_gui_option = false;

// If TRUE don't start the GUI.
// (--no-gui)
static bool no_gui_option = false;

// If TRUE, force readline command line editing.
// (--line-editing)
static bool forced_line_editing = false;

// If TRUE, initialize history list from saved history file.
// (--no-history; -H)
static bool read_history_file = true;

// The value of "path" specified on the command line.
// (--path; -p)
static std::list<std::string> command_line_path;

// The value for "EXEC_PATH" specified on the command line.
// (--exec-path)
static std::string exec_path;

// The value for "IMAGE_PATH" specified on the command line.
// (--image-path)
static std::string image_path;

// If TRUE, ignore the window system even if it is available.
// (--no-window-system)
static bool no_window_system = false;

// Usage message
static const char *usage_string =
  "octave [-HVdfhiqvx] [--debug] [--echo-commands] [--eval CODE]\n\
       [--exec-path path] [--force-gui] [--help] [--image-path path]\n\
       [--info-file file] [--info-program prog] [--interactive]\n\
       [--jit-debugging] [--line-editing] [--no-gui] [--no-history]\n\
       [--no-init-file] [--no-init-path] [--no-jit-compiler]\n\
       [--no-line-editing] [--no-site-file] [--no-window-system]\n\
       [-p path] [--path path] [--silent] [--traditional]\n\
       [--verbose] [--version] [file]";

// This is here so that it's more likely that the usage message and
// the real set of options will agree.  Note: the '+' must come first
// to prevent getopt from permuting arguments!
static const char *short_opts = "+HVdfhip:qvx";

// The code to evaluate at startup (--eval CODE)
static std::string code_to_eval;

// If TRUE, don't exit after evaluating code given by --eval option.
static bool persist = false;

// If TRUE, the GUI should be started.
static bool start_gui = false;

// Long options.  See the comments in getopt.h for the meanings of the
// fields in this structure.
#define BUILT_IN_DOCSTRINGS_FILE_OPTION 1
#define DOC_CACHE_FILE_OPTION 2
#define EVAL_OPTION 3
#define EXEC_PATH_OPTION 4
#define FORCE_GUI_OPTION 5
#define IMAGE_PATH_OPTION 6
#define INFO_FILE_OPTION 7
#define INFO_PROG_OPTION 8
#define JIT_DEBUGGING_OPTION 9
#define LINE_EDITING_OPTION 10
#define NO_GUI_OPTION 11
#define NO_INIT_FILE_OPTION 12
#define NO_INIT_PATH_OPTION 13
#define NO_JIT_COMPILER_OPTION 14
#define NO_LINE_EDITING_OPTION 15
#define NO_SITE_FILE_OPTION 16
#define NO_WINDOW_SYSTEM_OPTION 17
#define PERSIST_OPTION 18
#define TEXI_MACROS_FILE_OPTION 19
#define TRADITIONAL_OPTION 20
struct option long_opts[] = {
  { "braindead",                no_argument,       0, TRADITIONAL_OPTION },
  { "built-in-docstrings-file", required_argument, 0, BUILT_IN_DOCSTRINGS_FILE_OPTION },
  { "debug",                    no_argument,       0, 'd' },
  { "doc-cache-file",           required_argument, 0, DOC_CACHE_FILE_OPTION },
  { "echo-commands",            no_argument,       0, 'x' },
  { "eval",                     required_argument, 0, EVAL_OPTION },
  { "exec-path",                required_argument, 0, EXEC_PATH_OPTION },
  { "force-gui",                no_argument,       0, FORCE_GUI_OPTION },
  { "help",                     no_argument,       0, 'h' },
  { "image-path",               required_argument, 0, IMAGE_PATH_OPTION },
  { "info-file",                required_argument, 0, INFO_FILE_OPTION },
  { "info-program",             required_argument, 0, INFO_PROG_OPTION },
  { "interactive",              no_argument,       0, 'i' },
  { "jit-debugging",            no_argument,       0, JIT_DEBUGGING_OPTION },
  { "line-editing",             no_argument,       0, LINE_EDITING_OPTION },
  { "no-gui",                   no_argument,       0, NO_GUI_OPTION },
  { "no-history",               no_argument,       0, 'H' },
  { "no-init-file",             no_argument,       0, NO_INIT_FILE_OPTION },
  { "no-init-path",             no_argument,       0, NO_INIT_PATH_OPTION },
  { "no-jit-compiler",          no_argument,       0, NO_JIT_COMPILER_OPTION },
  { "no-line-editing",          no_argument,       0, NO_LINE_EDITING_OPTION },
  { "no-site-file",             no_argument,       0, NO_SITE_FILE_OPTION },
  { "no-window-system",         no_argument,       0, NO_WINDOW_SYSTEM_OPTION },
  { "norc",                     no_argument,       0, 'f' },
  { "path",                     required_argument, 0, 'p' },
  { "persist",                  no_argument,       0, PERSIST_OPTION },
  { "quiet",                    no_argument,       0, 'q' },
  { "silent",                   no_argument,       0, 'q' },
  { "texi-macros-file",         required_argument, 0, TEXI_MACROS_FILE_OPTION },
  { "traditional",              no_argument,       0, TRADITIONAL_OPTION },
  { "verbose",                  no_argument,       0, 'V' },
  { "version",                  no_argument,       0, 'v' },
  { 0,                          0,                 0, 0 }
};

// Store the command-line options for later use.

static void
intern_argv (int argc, char **argv)
{
  assert (symbol_table::at_top_level ());

  symbol_table::varref (".nargin.") = argc - 1;

  symbol_table::mark_hidden (".nargin.");

  if (argc > 0)
    {
      octave_argv.resize (argc - 1);

      // Skip program name in argv.
      int i = argc;
      while (--i > 0)
        octave_argv[i-1] = *(argv+i);
    }
}

DEFUN (__version_info__, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Built-in Function} {retval =} __version_info__ (@var{name}, @var{version}, @var{release}, @var{date})\n\
Undocumented internal function.\n\
@end deftypefn")
{
  octave_value retval;

  static octave_map vinfo;

  int nargin = args.length ();

  if (nargin == 4)
    {
      if (vinfo.nfields () == 0)
        {
          vinfo.assign ("Name", args (0));
          vinfo.assign ("Version", args (1));
          vinfo.assign ("Release", args (2));
          vinfo.assign ("Date", args (3));
        }
      else
        {
          octave_idx_type n = vinfo.numel () + 1;

          vinfo.resize (dim_vector (n, 1));

          octave_value idx (n);

          vinfo.assign (idx, "Name", Cell (octave_value (args (0))));
          vinfo.assign (idx, "Version", Cell (octave_value (args (1))));
          vinfo.assign (idx, "Release", Cell (octave_value (args (2))));
          vinfo.assign (idx, "Date", Cell (octave_value (args (3))));
        }
    }
  else if (nargin == 0)
    retval = vinfo;
  else
    print_usage ();

  return retval;
}

static void
initialize_version_info (void)
{
  octave_value_list args;

  args(3) = OCTAVE_RELEASE_DATE;
  args(2) = OCTAVE_RELEASE;
  args(1) = OCTAVE_VERSION;
  args(0) = "GNU Octave";

  F__version_info__ (args, 0);
}

static void
gripe_safe_source_exception (const std::string& file, const std::string& msg)
{
  std::cerr << "error: " << msg << "\n"
            << "error: execution of " << file << " failed\n"
            << "error: trying to make my way to a command prompt"
            << std::endl;
}

// Execute commands from a file and catch potential exceptions in a
// consistent way.  This function should be called anywhere we might
// parse and execute commands from a file before before we have entered
// the main loop in toplev.cc.

static void
safe_source_file (const std::string& file_name,
                  const std::string& context = std::string (),
                  bool verbose = false, bool require_file = true,
                  const std::string& warn_for = std::string ())
{
  try
    {
      source_file (file_name, context, verbose, require_file, warn_for);
    }
  catch (octave_interrupt_exception)
    {
      recover_from_exception ();
      octave_stdout << "\n";
      if (quitting_gracefully)
        clean_up_and_exit (exit_status);
    }
  catch (octave_execution_exception)
    {
      recover_from_exception ();
      gripe_safe_source_exception (file_name, "unhandled execution exception");
    }
}

// Initialize by reading startup files.

static void
execute_startup_files (void)
{
  unwind_protect frame;

  frame.protect_var (input_from_startup_file);

  input_from_startup_file = true;

  std::string context;

  bool verbose = (verbose_flag && ! inhibit_startup_message);

  bool require_file = false;

  if (read_site_files)
    {
      // Execute commands from the site-wide configuration file.
      // First from the file $(prefix)/lib/octave/site/m/octaverc
      // (if it exists), then from the file
      // $(prefix)/share/octave/$(version)/m/octaverc (if it exists).

      safe_source_file (Vlocal_site_defaults_file, context, verbose,
                        require_file);

      safe_source_file (Vsite_defaults_file, context, verbose, require_file);
    }

  if (read_init_files)
    {
      // Try to execute commands from $HOME/$OCTAVE_INITFILE and
      // $OCTAVE_INITFILE.  If $OCTAVE_INITFILE is not set, .octaverc
      // is assumed.

      bool home_rc_already_executed = false;

      std::string initfile = octave_env::getenv ("OCTAVE_INITFILE");

      if (initfile.empty ())
        initfile = ".octaverc";

      std::string home_dir = octave_env::get_home_directory ();

      std::string home_rc = octave_env::make_absolute (initfile, home_dir);

      std::string local_rc;

      if (! home_rc.empty ())
        {
          safe_source_file (home_rc, context, verbose, require_file);

          // Names alone are not enough.

          file_stat fs_home_rc (home_rc);

          if (fs_home_rc)
            {
              // We want to check for curr_dir after executing home_rc
              // because doing that may change the working directory.

              local_rc = octave_env::make_absolute (initfile);

              home_rc_already_executed = same_file (home_rc, local_rc);
            }
        }

      if (! home_rc_already_executed)
        {
          if (local_rc.empty ())
            local_rc = octave_env::make_absolute (initfile);

          safe_source_file (local_rc, context, verbose, require_file);
        }
    }
}

static int
execute_eval_option_code (const std::string& code)
{
  unwind_protect frame;

  octave_save_signal_mask ();

  can_interrupt = true;

  octave_signal_hook = octave_signal_handler;
  octave_interrupt_hook = 0;
  octave_bad_alloc_hook = 0;

  octave_catch_interrupts ();

  octave_initialized = true;

  frame.protect_var (interactive);

  interactive = false;

  int parse_status = 0;

  try
    {
      eval_string (code, false, parse_status, 0);
    }
  catch (octave_interrupt_exception)
    {
      recover_from_exception ();
      octave_stdout << "\n";
      if (quitting_gracefully)
        clean_up_and_exit (exit_status);
    }
  catch (octave_execution_exception)
    {
      recover_from_exception ();
      std::cerr << "error: unhandled execution exception -- eval failed"
                << std::endl;
    }

  return parse_status;
}

static void
execute_command_line_file (const std::string& fname)
{
  unwind_protect frame;

  octave_save_signal_mask ();

  can_interrupt = true;

  octave_signal_hook = octave_signal_handler;
  octave_interrupt_hook = 0;
  octave_bad_alloc_hook = 0;

  octave_catch_interrupts ();

  octave_initialized = true;

  frame.protect_var (interactive);
  frame.protect_var (reading_script_file);
  frame.protect_var (input_from_command_line_file);

  frame.protect_var (curr_fcn_file_name);
  frame.protect_var (curr_fcn_file_full_name);

  frame.protect_var (octave_program_invocation_name);
  frame.protect_var (octave_program_name);

  interactive = false;
  reading_script_file = true;
  input_from_command_line_file = true;

  curr_fcn_file_name = fname;
  curr_fcn_file_full_name = curr_fcn_file_name;

  octave_program_invocation_name = curr_fcn_file_name;

  size_t pos = curr_fcn_file_name.find_last_of (file_ops::dir_sep_chars ());

  std::string tmp = (pos != std::string::npos)
    ? curr_fcn_file_name.substr (pos+1) : curr_fcn_file_name;

  octave_program_name = tmp;

  std::string context;
  bool verbose = false;
  bool require_file = true;

  safe_source_file (fname, context, verbose, require_file, "octave");
}

// Usage message with extra help.

static void
verbose_usage (void)
{
  std::cout << OCTAVE_NAME_VERSION_COPYRIGHT_COPYING_AND_WARRANTY "\n\
\n\
Usage: octave [options] [FILE]\n\
\n\
Options:\n\
\n\
  --debug, -d             Enter parser debugging mode.\n\
  --doc-cache-file FILE   Use doc cache file FILE.\n\
  --echo-commands, -x     Echo commands as they are executed.\n\
  --eval CODE             Evaluate CODE.  Exit when done unless --persist.\n\
  --exec-path PATH        Set path for executing subprograms.\n\
  --force-gui             Force graphical user interface to start.\n\
  --help, -h,             Print short help message and exit.\n\
  --image-path PATH       Add PATH to head of image search path.\n\
  --info-file FILE        Use top-level info file FILE.\n\
  --info-program PROGRAM  Use PROGRAM for reading info files.\n\
  --interactive, -i       Force interactive behavior.\n\
  --jit-debug             Enable JIT compiler debugging/tracing.\n\
  --line-editing          Force readline use for command-line editing.\n\
  --no-gui                Disable the graphical user interface.\n\
  --no-history, -H        Don't save commands to the history list\n\
  --no-init-file          Don't read the ~/.octaverc or .octaverc files.\n\
  --no-init-path          Don't initialize function search path.\n\
  --no-jit-compiler       Disable the JIT compiler.\n\
  --no-line-editing       Don't use readline for command-line editing.\n\
  --no-site-file          Don't read the site-wide octaverc file.\n\
  --no-window-system      Disable window system, including graphics.\n\
  --norc, -f              Don't read any initialization files.\n\
  --path PATH, -p PATH    Add PATH to head of function search path.\n\
  --persist               Go interactive after --eval or reading from FILE.\n\
  --silent, -q            Don't print message at startup.\n\
  --texi-macros-file FILE Use Texinfo macros in FILE for makeinfo command.\n\
  --traditional           Set variables for closer MATLAB compatibility.\n\
  --verbose, -V           Enable verbose output in some cases.\n\
  --version, -v           Print version number and exit.\n\
\n\
  FILE                    Execute commands from FILE.  Exit when done\n\
                          unless --persist is also specified.\n\
\n"
OCTAVE_WWW_STATEMENT "\n\
\n"
OCTAVE_CONTRIB_STATEMENT "\n\
\n"
OCTAVE_BUGS_STATEMENT "\n";

  exit (0);
}

// Terse usage messsage.

static void
usage (void)
{
  std::cerr << "\nusage: " << usage_string << "\n\n";
  exit (1);
}

static void
print_version_and_exit (void)
{
  std::cout << OCTAVE_NAME_VERSION_COPYRIGHT_COPYING_WARRANTY_AND_BUGS "\n";
  exit (0);
}

static void
lo_error_handler (const char *fmt, ...)
{
  va_list args;
  va_start (args, fmt);
  verror_with_cfn (fmt, args);
  va_end (args);

  octave_throw_execution_exception ();
}

static void
lo_error_with_id_handler (const char *id, const char *fmt, ...)
{
  va_list args;
  va_start (args, fmt);
  verror_with_id_cfn (id, fmt, args);
  va_end (args);

  octave_throw_execution_exception ();
}

static void
initialize_error_handlers ()
{
  set_liboctave_error_handler (lo_error_handler);
  set_liboctave_error_with_id_handler (lo_error_with_id_handler);
  set_liboctave_warning_handler (warning);
  set_liboctave_warning_with_id_handler (warning_with_id);
}

// What happens on --traditional.

static void
maximum_braindamage (void)
{
  persist = true;

  FPS1 (octave_value (">> "));
  FPS2 (octave_value (""));
  FPS4 (octave_value (""));
  Fallow_noninteger_range_as_index (octave_value (true));
  Fbeep_on_error (octave_value (true));
  Fconfirm_recursive_rmdir (octave_value (false));
  Fcrash_dumps_octave_core (octave_value (false));
  Fdefault_save_options (octave_value ("-mat-binary"));
  Fdo_braindead_shortcircuit_evaluation (octave_value (true));
  Ffixed_point_format (octave_value (true));
  Fhistory_timestamp_format_string (octave_value ("%%-- %D %I:%M %p --%%"));
  Fpage_screen_output (octave_value (false));
  Fprint_empty_dimensions (octave_value (false));

  disable_warning ("Octave:abbreviated-property-match");
  disable_warning ("Octave:fopen-file-in-path");
  disable_warning ("Octave:function-name-clash");
  disable_warning ("Octave:load-file-in-path");
  disable_warning ("Octave:possible-matlab-short-circuit-operator");
}

// EMBEDDED is declared int instead of bool because this function is
// declared extern "C".

int
octave_main (int argc, char **argv, int embedded)
{
  octave_process_command_line (argc, argv);

  sysdep_init ();

  install_defaults ();

  octave_initialize_interpreter (argc, argv, embedded);

  return octave_execute_interpreter ();
}

void
octave_process_command_line (int argc, char **argv)
{
  octave_cmdline_argc = argc;
  octave_cmdline_argv = argv;

  while (true)
    {
      int long_idx;

      int optc = getopt_long (argc, argv, short_opts, long_opts, &long_idx);

      if (optc < 0)
        break;

      switch (optc)
        {
        case '?':
          // Unrecognized option.  getopt_long already printed a
          // message about that, so we will just print the usage string
          // and exit.
          usage ();
          break;

        case 'H':
          Fsaving_history (octave_value (false));
          read_history_file = false;
          break;

        case 'V':
          verbose_flag = true;
          break;

        case 'd':
          // This is the same as yydebug in parse.y.
          octave_debug++;
          break;

        case 'f':
          read_init_files = false;
          read_site_files = false;
          break;

        case 'h':
          verbose_usage ();
          break;

        case 'i':
          forced_interactive = true;
          break;

        case 'p':
          if (optarg)
            command_line_path.push_back (optarg);
          break;

        case 'q':
          inhibit_startup_message = true;
          break;

        case 'x':
          {
            int val = ECHO_SCRIPTS | ECHO_FUNCTIONS | ECHO_CMD_LINE;
            Fecho_executing_commands (octave_value (val));
          }
          break;

        case 'v':
          print_version_and_exit ();
          break;

        case BUILT_IN_DOCSTRINGS_FILE_OPTION:
          if (optarg)
            Fbuilt_in_docstrings_file (octave_value (optarg));
          break;

        case DOC_CACHE_FILE_OPTION:
          if (optarg)
            Fdoc_cache_file (octave_value (optarg));
          break;

        case EVAL_OPTION:
          if (optarg)
            {
              if (code_to_eval.empty ())
                code_to_eval = optarg;
              else
                code_to_eval += std::string (" ") + optarg;
            }
          break;

        case EXEC_PATH_OPTION:
          if (optarg)
            exec_path = optarg;
          break;

        case FORCE_GUI_OPTION:
          force_gui_option = true;
          break;

        case IMAGE_PATH_OPTION:
          if (optarg)
            image_path = optarg;
          break;

        case INFO_FILE_OPTION:
          if (optarg)
            Finfo_file (octave_value (optarg));
          break;

        case INFO_PROG_OPTION:
          if (optarg)
            Finfo_program (octave_value (optarg));
          break;

        case JIT_DEBUGGING_OPTION:
          Fenable_jit_debugging (octave_value (true));
          break;

        case LINE_EDITING_OPTION:
          forced_line_editing = true;
          break;

        case NO_GUI_OPTION:
          no_gui_option = true;
          break;

        case NO_INIT_FILE_OPTION:
          read_init_files = false;
          break;

        case NO_INIT_PATH_OPTION:
          set_initial_path = false;
          break;

        case NO_JIT_COMPILER_OPTION:
          Fenable_jit_compiler (octave_value (false));
          break;

        case NO_LINE_EDITING_OPTION:
          line_editing = false;
          break;

        case NO_SITE_FILE_OPTION:
          read_site_files = 0;
          break;

        case NO_WINDOW_SYSTEM_OPTION:
          no_window_system = true;
          break;

        case PERSIST_OPTION:
          persist = true;
          break;

        case TEXI_MACROS_FILE_OPTION:
          if (optarg)
            Ftexi_macros_file (octave_value (optarg));
          break;

        case TRADITIONAL_OPTION:
          maximum_braindamage ();
          break;

        default:
          // getopt_long should print a message about unrecognized
          // options and return '?', which is handled above.  So if we
          // end up here, it is because there was an option but we
          // forgot to handle it.  That should be fatal.
          panic_impossible ();
          break;
        }
    }

  if (force_gui_option && no_gui_option)
    {
      error ("error: only one of --force-gui and --no-gui may be used");
      usage ();
    }
}

// EMBEDDED is declared int instead of bool because this function is
// declared extern "C".

void
octave_initialize_interpreter (int argc, char **argv, int embedded)
{
  octave_embedded = embedded;

  octave_env::set_program_name (argv[0]);

  octave_program_invocation_name = octave_env::get_program_invocation_name ();
  octave_program_name = octave_env::get_program_name ();

  octave_thread::init ();

  init_signals ();

  octave_ieee_init ();

  // The idea here is to force xerbla to be referenced so that we will
  // link to our own version instead of the one provided by the BLAS
  // library.  But octave_NaN should never be -1, so we should never
  // actually call xerbla.

  if (octave_NaN == -1)
    F77_FUNC (xerbla, XERBLA) ("octave", 13 F77_CHAR_ARG_LEN (6));

  initialize_error_handlers ();

  initialize_default_warning_state ();

  if (! embedded)
    install_signal_handlers ();
  else
    quit_allowed = false;

  initialize_file_io ();

  install_types ();

  install_ops ();

  install_builtins ();

  for (std::list<std::string>::const_iterator it = command_line_path.begin ();
       it != command_line_path.end (); it++)
    load_path::set_command_line_path (*it);

  if (! exec_path.empty ())
    set_exec_path (exec_path);

  if (! image_path.empty ())
    set_image_path (image_path);

  if (no_window_system)
    display_info::no_window_system ();

  // Make sure we clean up when we exit.  Also allow users to register
  // functions.  If we don't have atexit or on_exit, we're going to
  // leave some junk files around if we exit abnormally.

  atexit (do_octave_atexit);

  // Is input coming from a terminal?  If so, we are probably
  // interactive.

  // If stdin is not a tty, then we are reading commands from a pipe or
  // a redirected file.
  stdin_is_tty = gnulib::isatty (fileno (stdin));

  interactive = (! embedded && stdin_is_tty
                 && gnulib::isatty (fileno (stdout)));

  if (! interactive && ! forced_line_editing)
    line_editing = false;

  // Force default line editor if we don't want readline editing.
  if (! line_editing)
    command_editor::force_default_editor ();

  // These can come after command line args since none of them set any
  // defaults that might be changed by command line options.

  if (line_editing)
    initialize_command_input ();

  octave_interpreter_ready = true;

  initialize_version_info ();

  // Make all command-line arguments available to startup files,
  // including PKG_ADD files.

  intern_argv (argc, argv);

  load_path::initialize (set_initial_path);

  initialize_history (read_history_file);
}

int
octave_execute_interpreter (void)
{
  if (! inhibit_startup_message)
    std::cout << OCTAVE_STARTUP_MESSAGE "\n" << std::endl;

  execute_startup_files ();

  if (! inhibit_startup_message && reading_startup_message_printed)
    std::cout << std::endl;

  // If there is an extra argument, see if it names a file to read.
  // Additional arguments are taken as command line options for the
  // script.

  int last_arg_idx = optind;

  int remaining_args = octave_cmdline_argc - last_arg_idx;

  if (! code_to_eval.empty ())
    {
      int parse_status = execute_eval_option_code (code_to_eval);

      if (! (persist || remaining_args > 0))
        clean_up_and_exit (parse_status || error_state ? 1 : 0);
    }

  if (remaining_args > 0)
    {
      // If we are running an executable script (#! /bin/octave) then
      // we should only see the args passed to the script.

      intern_argv (remaining_args, octave_cmdline_argv+last_arg_idx);

      execute_command_line_file (octave_cmdline_argv[last_arg_idx]);

      if (! persist)
        {
          quitting_gracefully = true;

          clean_up_and_exit (error_state ? 1 : 0);
        }
    }

  // Avoid counting commands executed from startup files.

  command_editor::reset_current_command_number (1);

  // Now argv should have the full set of args.
  intern_argv (octave_cmdline_argc, octave_cmdline_argv);

  if (! octave_embedded)
    switch_to_buffer (create_buffer (get_input_from_stdin ()));

  // Force input to be echoed if not really interactive, but the user
  // has forced interactive behavior.

  if (! interactive && forced_interactive)
    {
      command_editor::blink_matching_paren (false);

      // FIXME -- is this the right thing to do?

      Fecho_executing_commands (octave_value (ECHO_CMD_LINE));
    }

  if (octave_embedded)
    {
      // FIXME -- do we need to do any cleanup here before
      // returning?  If we don't, what will happen to Octave functions
      // that have been registered to execute with atexit, for example?

      return 1;
    }

  int retval = main_loop ();

  if (retval == 1 && ! error_state)
    retval = 0;

  quitting_gracefully = true;

  clean_up_and_exit (retval);

  return 0;
}

static bool
check_starting_gui (void)
{
  if (no_window_system || ! display_info::display_available ())
    return false;

  if (force_gui_option)
    return true;

  if (no_gui_option)
    return false;

  if (persist)
    return true;

  // If stdin is not a tty, then assume we are reading commands from a
  // pipe or a redirected file and the GUI should not start.  If this is
  // not the case (for example, starting from a desktop "launcher" with
  // no terminal) and you want to start the GUI, you may use the
  // --force-gui option to start the GUI.

  if (! gnulib::isatty (fileno (stdin)))
    return false;

  // If we have code to eval or execute from a file, and we are going to
  // exit immediately after executing it, don't start the gui.

  int last_arg_idx = optind;
  int remaining_args = octave_cmdline_argc - last_arg_idx;

  if (! code_to_eval.empty () || remaining_args > 0)
    return false;

  return true;
}

// Return int instead of bool because this function is declared
// extern "C".

int
octave_starting_gui (void)
{
  start_gui = check_starting_gui ();
  return start_gui;
}

DEFUN (isguirunning, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Built-in Function} {} isguirunning ()\n\
Return true if Octave is running in GUI mode and false otherwise.\n\
@end deftypefn")
{
  octave_value retval;

  if (args.length () == 0)
    retval = start_gui;
  else
    print_usage ();

  return retval;
}

/*
%!assert (islogical (isguirunning ()))
%!error isguirunning (1)
*/

DEFUN (argv, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Built-in Function} {} argv ()\n\
Return the command line arguments passed to Octave.  For example,\n\
if you invoked Octave using the command\n\
\n\
@example\n\
octave --no-line-editing --silent\n\
@end example\n\
\n\
@noindent\n\
@code{argv} would return a cell array of strings with the elements\n\
@option{--no-line-editing} and @option{--silent}.\n\
\n\
If you write an executable Octave script, @code{argv} will return the\n\
list of arguments passed to the script.  @xref{Executable Octave Programs},\n\
for an example of how to create an executable Octave script.\n\
@end deftypefn")
{
  octave_value retval;

  if (args.length () == 0)
    retval = Cell (octave_argv);
  else
    print_usage ();

  return retval;
}

/*
%!assert (iscellstr (argv ()))
%!error argv (1)
*/

DEFUN (program_invocation_name, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Built-in Function} {} program_invocation_name ()\n\
Return the name that was typed at the shell prompt to run Octave.\n\
\n\
If executing a script from the command line (e.g., @code{octave foo.m})\n\
or using an executable Octave script, the program name is set to the\n\
name of the script.  @xref{Executable Octave Programs}, for an example of\n\
how to create an executable Octave script.\n\
@seealso{program_name}\n\
@end deftypefn")
{
  octave_value retval;

  if (args.length () == 0)
    retval = octave_program_invocation_name;
  else
    print_usage ();

  return retval;
}

/*
%!assert (ischar (program_invocation_name ()))
%!error program_invocation_name (1)
*/

DEFUN (program_name, args, ,
  "-*- texinfo -*-\n\
@deftypefn {Built-in Function} {} program_name ()\n\
Return the last component of the value returned by\n\
@code{program_invocation_name}.\n\
@seealso{program_invocation_name}\n\
@end deftypefn")
{
  octave_value retval;

  if (args.length () == 0)
    retval = octave_program_name;
  else
    print_usage ();

  return retval;
}

/*
%!assert (ischar (program_name ()))
%!error program_name (1)
*/