shell.c

/* shell.c -- GNU's idea of the POSIX shell specification. */

/* Copyright (C) 1987-2019 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash 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.

   Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
  Birthdate:
  Sunday, January 10th, 1988.
  Initial author: Brian Fox
*/
#define INSTALL_DEBUG_MODE

#include "config.h"

#include "bashtypes.h"
#if !defined (_MINIX) && defined (HAVE_SYS_FILE_H)
#  include <sys/file.h>
#endif
#include "posixstat.h"
#include "posixtime.h"
#include "bashansi.h"
#include <stdio.h>
#include <signal.h>
#include <errno.h>
#include "filecntl.h"
#if defined (HAVE_PWD_H)
#  include <pwd.h>
#endif

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif

#include "bashintl.h"

#define NEED_SH_SETLINEBUF_DECL		/* used in externs.h */

#include "shell.h"
#include "parser.h"
#include "flags.h"
#include "trap.h"
#include "mailcheck.h"
#include "builtins.h"
#include "builtins/common.h"

#if defined (JOB_CONTROL)
#include "jobs.h"
#else
extern int running_in_background;
extern int initialize_job_control PARAMS((int));
extern int get_tty_state PARAMS((void));
#endif /* JOB_CONTROL */

#include "input.h"
#include "execute_cmd.h"
#include "findcmd.h"

#if defined (USING_BASH_MALLOC) && defined (DEBUG) && !defined (DISABLE_MALLOC_WRAPPERS)
#  include <malloc/shmalloc.h>
#endif

#if defined (HISTORY)
#  include "bashhist.h"
#  include <readline/history.h>
#endif

#if defined (READLINE)
#  include <readline/readline.h>
#  include "bashline.h"
#endif

#include <tilde/tilde.h>
#include <glob/strmatch.h>

#if defined (__OPENNT)
#  include <opennt/opennt.h>
#endif

#if !defined (HAVE_GETPW_DECLS)
extern struct passwd *getpwuid ();
#endif /* !HAVE_GETPW_DECLS */

#if !defined (errno)
extern int errno;
#endif

#if defined (NO_MAIN_ENV_ARG)
extern char **environ;	/* used if no third argument to main() */
#endif

extern int gnu_error_format;

/* Non-zero means that this shell has already been run; i.e. you should
   call shell_reinitialize () if you need to start afresh. */
int shell_initialized = 0;
int bash_argv_initialized = 0;

COMMAND *global_command = (COMMAND *)NULL;

/* Information about the current user. */
struct user_info current_user =
{
  (uid_t)-1, (uid_t)-1, (gid_t)-1, (gid_t)-1,
  (char *)NULL, (char *)NULL, (char *)NULL
};

/* The current host's name. */
char *current_host_name = (char *)NULL;

/* Non-zero means that this shell is a login shell.
   Specifically:
   0 = not login shell.
   1 = login shell from getty (or equivalent fake out)
  -1 = login shell from "--login" (or -l) flag.
  -2 = both from getty, and from flag.
 */
int login_shell = 0;

/* Non-zero means that at this moment, the shell is interactive.  In
   general, this means that the shell is at this moment reading input
   from the keyboard. */
int interactive = 0;

/* Non-zero means that the shell was started as an interactive shell. */
int interactive_shell = 0;

/* Non-zero means to send a SIGHUP to all jobs when an interactive login
   shell exits. */
int hup_on_exit = 0;

/* Non-zero means to list status of running and stopped jobs at shell exit */
int check_jobs_at_exit = 0;

/* Non-zero means to change to a directory name supplied as a command name */
int autocd = 0;

/* Tells what state the shell was in when it started:
	0 = non-interactive shell script
	1 = interactive
	2 = -c command
	3 = wordexp evaluation
   This is a superset of the information provided by interactive_shell.
*/
int startup_state = 0;
int reading_shell_script = 0;

/* Special debugging helper. */
int debugging_login_shell = 0;

/* The environment that the shell passes to other commands. */
char **shell_environment;

/* Non-zero when we are executing a top-level command. */
int executing = 0;

/* The number of commands executed so far. */
int current_command_number = 1;

/* Non-zero is the recursion depth for commands. */
int indirection_level = 0;

/* The name of this shell, as taken from argv[0]. */
char *shell_name = (char *)NULL;

/* time in seconds when the shell was started */
time_t shell_start_time;
struct timeval shellstart;

/* Are we running in an emacs shell window? */
int running_under_emacs;

/* Do we have /dev/fd? */
#ifdef HAVE_DEV_FD
int have_devfd = HAVE_DEV_FD;
#else
int have_devfd = 0;
#endif

/* The name of the .(shell)rc file. */
static char *bashrc_file = DEFAULT_BASHRC;

/* Non-zero means to act more like the Bourne shell on startup. */
static int act_like_sh;

/* Non-zero if this shell is being run by `su'. */
static int su_shell;

/* Non-zero if we have already expanded and sourced $ENV. */
static int sourced_env;

/* Is this shell running setuid? */
static int running_setuid;

/* Values for the long-winded argument names. */
static int debugging;			/* Do debugging things. */
static int no_rc;			/* Don't execute ~/.bashrc */
static int no_profile;			/* Don't execute .profile */
static int do_version;			/* Display interesting version info. */
static int make_login_shell;		/* Make this shell be a `-bash' shell. */
static int want_initial_help;		/* --help option */

int debugging_mode = 0;		/* In debugging mode with --debugger */
#if defined (READLINE)
int no_line_editing = 0;	/* non-zero -> don't do fancy line editing. */
#else
int no_line_editing = 1;	/* can't have line editing without readline */
#endif
int dump_translatable_strings;	/* Dump strings in $"...", don't execute. */
int dump_po_strings;		/* Dump strings in $"..." in po format */
int wordexp_only = 0;		/* Do word expansion only */
int protected_mode = 0;		/* No command substitution with --wordexp */

int pretty_print_mode = 0;	/* pretty-print a shell script */

#if defined (STRICT_POSIX)
int posixly_correct = 1;	/* Non-zero means posix.2 superset. */
#else
int posixly_correct = 0;	/* Non-zero means posix.2 superset. */
#endif

/* Some long-winded argument names.  These are obviously new. */
#define Int 1
#define Charp 2
static const struct {
  const char *name;
  int type;
  int *int_value;
  char **char_value;
} long_args[] = {
  { "debug", Int, &debugging, (char **)0x0 },
#if defined (DEBUGGER)
  { "debugger", Int, &debugging_mode, (char **)0x0 },
#endif
  { "dump-po-strings", Int, &dump_po_strings, (char **)0x0 },
  { "dump-strings", Int, &dump_translatable_strings, (char **)0x0 },
  { "help", Int, &want_initial_help, (char **)0x0 },
  { "init-file", Charp, (int *)0x0, &bashrc_file },
  { "login", Int, &make_login_shell, (char **)0x0 },
  { "noediting", Int, &no_line_editing, (char **)0x0 },
  { "noprofile", Int, &no_profile, (char **)0x0 },
  { "norc", Int, &no_rc, (char **)0x0 },
  { "posix", Int, &posixly_correct, (char **)0x0 },
  { "pretty-print", Int, &pretty_print_mode, (char **)0x0 },
#if defined (WORDEXP_OPTION)
  { "protected", Int, &protected_mode, (char **)0x0 },
#endif
  { "rcfile", Charp, (int *)0x0, &bashrc_file },
#if defined (RESTRICTED_SHELL)
  { "restricted", Int, &restricted, (char **)0x0 },
#endif
  { "verbose", Int, &verbose_flag, (char **)0x0 },
  { "version", Int, &do_version, (char **)0x0 },
#if defined (WORDEXP_OPTION)
  { "wordexp", Int, &wordexp_only, (char **)0x0 },
#endif
  { (char *)0x0, Int, (int *)0x0, (char **)0x0 }
};

/* These are extern so execute_simple_command can set them, and then
   longjmp back to main to execute a shell script, instead of calling
   main () again and resulting in indefinite, possibly fatal, stack
   growth. */
procenv_t subshell_top_level;
int subshell_argc;
char **subshell_argv;
char **subshell_envp;

char *exec_argv0;

#if defined (BUFFERED_INPUT)
/* The file descriptor from which the shell is reading input. */
int default_buffered_input = -1;
#endif

/* The following two variables are not static so they can show up in $-. */
int read_from_stdin;		/* -s flag supplied */
int want_pending_command;	/* -c flag supplied */

/* This variable is not static so it can be bound to $BASH_EXECUTION_STRING */
char *command_execution_string;	/* argument to -c option */
char *shell_script_filename; 	/* shell script */

int malloc_trace_at_exit = 0;

static int shell_reinitialized = 0;

static FILE *default_input;

static STRING_INT_ALIST *shopt_alist;
static int shopt_ind = 0, shopt_len = 0;

static int parse_long_options PARAMS((char **, int, int));
static int parse_shell_options PARAMS((char **, int, int));
static int bind_args PARAMS((char **, int, int, int));

static void start_debugger PARAMS((void));

static void add_shopt_to_alist PARAMS((char *, int));
static void run_shopt_alist PARAMS((void));

static void execute_env_file PARAMS((char *));
static void run_startup_files PARAMS((void));
static int open_shell_script PARAMS((char *));
static void set_bash_input PARAMS((void));
static int run_one_command PARAMS((char *));
#if defined (WORDEXP_OPTION)
static int run_wordexp PARAMS((char *));
#endif

static int uidget PARAMS((void));

static void set_option_defaults PARAMS((void));
static void reset_option_defaults PARAMS((void));

static void init_interactive PARAMS((void));
static void init_noninteractive PARAMS((void));
static void init_interactive_script PARAMS((void));

static void set_shell_name PARAMS((char *));
static void shell_initialize PARAMS((void));
static void shell_reinitialize PARAMS((void));

static void show_shell_usage PARAMS((FILE *, int));

#ifdef __CYGWIN__
static void
_cygwin32_check_tmp ()
{
  struct stat sb;

  if (stat ("/tmp", &sb) < 0)
    internal_warning (_("could not find /tmp, please create!"));
  else
    {
      if (S_ISDIR (sb.st_mode) == 0)
	internal_warning (_("/tmp must be a valid directory name"));
    }
}
#endif /* __CYGWIN__ */

#if defined (NO_MAIN_ENV_ARG)
/* systems without third argument to main() */
int
main (argc, argv)
     int argc;
     char **argv;
#else /* !NO_MAIN_ENV_ARG */
int
main (argc, argv, env)
     int argc;
     char **argv, **env;
#endif /* !NO_MAIN_ENV_ARG */
{
  register int i;
  int code, old_errexit_flag;
#if defined (RESTRICTED_SHELL)
  int saverst;
#endif
  volatile int locally_skip_execution;
  volatile int arg_index, top_level_arg_index;
#ifdef __OPENNT
  char **env;

  env = environ;
#endif /* __OPENNT */

  USE_VAR(argc);
  USE_VAR(argv);
  USE_VAR(env);
  USE_VAR(code);
  USE_VAR(old_errexit_flag);
#if defined (RESTRICTED_SHELL)
  USE_VAR(saverst);
#endif

  /* Catch early SIGINTs. */
  code = setjmp_nosigs (top_level);
  if (code)
    exit (2);

  xtrace_init ();

#if defined (USING_BASH_MALLOC) && defined (DEBUG) && !defined (DISABLE_MALLOC_WRAPPERS)
  malloc_set_register (1);	/* XXX - change to 1 for malloc debugging */
#endif

  check_dev_tty ();

#ifdef __CYGWIN__
  _cygwin32_check_tmp ();
#endif /* __CYGWIN__ */

  /* Wait forever if we are debugging a login shell. */
  while (debugging_login_shell) sleep (3);

  set_default_locale ();

  running_setuid = uidget ();

  if (getenv ("POSIXLY_CORRECT") || getenv ("POSIX_PEDANTIC"))
    posixly_correct = 1;

#if defined (USE_GNU_MALLOC_LIBRARY)
  mcheck (programming_error, (void (*) ())0);
#endif /* USE_GNU_MALLOC_LIBRARY */

  if (setjmp_sigs (subshell_top_level))
    {
      argc = subshell_argc;
      argv = subshell_argv;
      env = subshell_envp;
      sourced_env = 0;
    }

  shell_reinitialized = 0;

  /* Initialize `local' variables for all `invocations' of main (). */
  arg_index = 1;
  if (arg_index > argc)
    arg_index = argc;
  command_execution_string = shell_script_filename = (char *)NULL;
  want_pending_command = locally_skip_execution = read_from_stdin = 0;
  default_input = stdin;
#if defined (BUFFERED_INPUT)
  default_buffered_input = -1;
#endif

  /* Fix for the `infinite process creation' bug when running shell scripts
     from startup files on System V. */
  login_shell = make_login_shell = 0;

  /* If this shell has already been run, then reinitialize it to a
     vanilla state. */
  if (shell_initialized || shell_name)
    {
      /* Make sure that we do not infinitely recurse as a login shell. */
      if (*shell_name == '-')
	shell_name++;

      shell_reinitialize ();
      if (setjmp_nosigs (top_level))
	exit (2);
    }

  shell_environment = env;
  set_shell_name (argv[0]);

  gettimeofday (&shellstart, 0);
  shell_start_time = shellstart.tv_sec;

  /* Parse argument flags from the input line. */

  /* Find full word arguments first. */
  arg_index = parse_long_options (argv, arg_index, argc);
  
  if (want_initial_help)
    {
      show_shell_usage (stdout, 1);
      exit (EXECUTION_SUCCESS);
    }

  if (do_version)
    {
      show_shell_version (1);
      exit (EXECUTION_SUCCESS);
    }

  echo_input_at_read = verbose_flag;	/* --verbose given */

  /* All done with full word options; do standard shell option parsing.*/
  this_command_name = shell_name;	/* for error reporting */
  arg_index = parse_shell_options (argv, arg_index, argc);

  /* If user supplied the "--login" (or -l) flag, then set and invert
     LOGIN_SHELL. */
  if (make_login_shell)
    {
      login_shell++;
      login_shell = -login_shell;
    }

  set_login_shell ("login_shell", login_shell != 0);

  if (dump_po_strings)
    dump_translatable_strings = 1;

  if (dump_translatable_strings)
    read_but_dont_execute = 1;

  if (running_setuid && privileged_mode == 0)
    disable_priv_mode ();

  /* Need to get the argument to a -c option processed in the
     above loop.  The next arg is a command to execute, and the
     following args are $0...$n respectively. */
  if (want_pending_command)
    {
      command_execution_string = argv[arg_index];
      if (command_execution_string == 0)
	{
	  report_error (_("%s: option requires an argument"), "-c");
	  exit (EX_BADUSAGE);
	}
      arg_index++;
    }
  this_command_name = (char *)NULL;

  /* First, let the outside world know about our interactive status.
     A shell is interactive if the `-i' flag was given, or if all of
     the following conditions are met:
	no -c command
	no arguments remaining or the -s flag given
	standard input is a terminal
	standard error is a terminal
     Refer to Posix.2, the description of the `sh' utility. */

  if (forced_interactive ||		/* -i flag */
      (!command_execution_string &&	/* No -c command and ... */
       wordexp_only == 0 &&		/* No --wordexp and ... */
       ((arg_index == argc) ||		/*   no remaining args or... */
	read_from_stdin) &&		/*   -s flag with args, and */
       isatty (fileno (stdin)) &&	/* Input is a terminal and */
       isatty (fileno (stderr))))	/* error output is a terminal. */
    init_interactive ();
  else
    init_noninteractive ();

  /*
   * Some systems have the bad habit of starting login shells with lots of open
   * file descriptors.  For instance, most systems that have picked up the
   * pre-4.0 Sun YP code leave a file descriptor open each time you call one
   * of the getpw* functions, and it's set to be open across execs.  That
   * means one for login, one for xterm, one for shelltool, etc.  There are
   * also systems that open persistent FDs to other agents or files as part
   * of process startup; these need to be set to be close-on-exec.
   */
  if (login_shell && interactive_shell)
    {
      for (i = 3; i < 20; i++)
	SET_CLOSE_ON_EXEC (i);
    }

  /* If we're in a strict Posix.2 mode, turn on interactive comments,
     alias expansion in non-interactive shells, and other Posix.2 things. */
  if (posixly_correct)
    {
      bind_variable ("POSIXLY_CORRECT", "y", 0);
      sv_strict_posix ("POSIXLY_CORRECT");
    }

  /* Now we run the shopt_alist and process the options. */
  if (shopt_alist)
    run_shopt_alist ();

  /* From here on in, the shell must be a normal functioning shell.
     Variables from the environment are expected to be set, etc. */
  shell_initialize ();

  set_default_lang ();
  set_default_locale_vars ();

  /*
   * M-x term -> TERM=eterm-color INSIDE_EMACS='251,term:0.96' (eterm)
   * M-x shell -> TERM='dumb' INSIDE_EMACS='25.1,comint' (no line editing)
   *
   * Older versions of Emacs may set EMACS to 't' or to something like
   * '22.1 (term:0.96)' instead of (or in addition to) setting INSIDE_EMACS.
   * They may set TERM to 'eterm' instead of 'eterm-color'.  They may have
   * a now-obsolete command that sets neither EMACS nor INSIDE_EMACS:
   * M-x terminal -> TERM='emacs-em7955' (line editing)
   */
  if (interactive_shell)
    {
      char *term, *emacs, *inside_emacs;
      int emacs_term, in_emacs;

      term = get_string_value ("TERM");
      emacs = get_string_value ("EMACS");
      inside_emacs = get_string_value ("INSIDE_EMACS");

      if (inside_emacs)
	{
	  emacs_term = strstr (inside_emacs, ",term:") != 0;
	  in_emacs = 1;
	}
      else if (emacs)
	{
	  /* Infer whether we are in an older Emacs. */
	  emacs_term = strstr (emacs, " (term:") != 0;
	  in_emacs = emacs_term || STREQ (emacs, "t");
	}
      else
	in_emacs = emacs_term = 0;

      /* Not sure any emacs terminal emulator sets TERM=emacs any more */
      no_line_editing |= STREQ (term, "emacs");
      no_line_editing |= in_emacs && STREQ (term, "dumb");

      /* running_under_emacs == 2 for `eterm' */
      running_under_emacs = in_emacs || STREQN (term, "emacs", 5);
      running_under_emacs += emacs_term && STREQN (term, "eterm", 5);

      if (running_under_emacs)
	gnu_error_format = 1;
    }

  top_level_arg_index = arg_index;
  old_errexit_flag = exit_immediately_on_error;

  /* Give this shell a place to longjmp to before executing the
     startup files.  This allows users to press C-c to abort the
     lengthy startup. */
  code = setjmp_sigs (top_level);
  if (code)
    {
      if (code == EXITPROG || code == ERREXIT)
	exit_shell (last_command_exit_value);
      else
	{
#if defined (JOB_CONTROL)
	  /* Reset job control, since run_startup_files turned it off. */
	  set_job_control (interactive_shell);
#endif
	  /* Reset value of `set -e', since it's turned off before running
	     the startup files. */
	  exit_immediately_on_error += old_errexit_flag;
	  locally_skip_execution++;
	}
    }

  arg_index = top_level_arg_index;

  /* Execute the start-up scripts. */

  if (interactive_shell == 0)
    {
      unbind_variable ("PS1");
      unbind_variable ("PS2");
      interactive = 0;
#if 0
      /* This has already been done by init_noninteractive */
      expand_aliases = posixly_correct;
#endif
    }
  else
    {
      change_flag ('i', FLAG_ON);
      interactive = 1;
    }

#if defined (RESTRICTED_SHELL)
  /* Set restricted_shell based on whether the basename of $0 indicates that
     the shell should be restricted or if the `-r' option was supplied at
     startup. */
  restricted_shell = shell_is_restricted (shell_name);

  /* If the `-r' option is supplied at invocation, make sure that the shell
     is not in restricted mode when running the startup files. */
  saverst = restricted;
  restricted = 0;
#endif

  /* Set positional parameters before running startup files. top_level_arg_index
     holds the index of the current argument before setting the positional
     parameters, so any changes performed in the startup files won't affect
     later option processing. */
  if (wordexp_only)
    ;			/* nothing yet */
  else if (command_execution_string)
    arg_index = bind_args (argv, arg_index, argc, 0);	/* $0 ... $n */
  else if (arg_index != argc && read_from_stdin == 0)
    {
      shell_script_filename = argv[arg_index++];
      arg_index = bind_args (argv, arg_index, argc, 1);	/* $1 ... $n */
    }
  else
    arg_index = bind_args (argv, arg_index, argc, 1);	/* $1 ... $n */

  /* The startup files are run with `set -e' temporarily disabled. */
  if (locally_skip_execution == 0 && running_setuid == 0)
    {
      old_errexit_flag = exit_immediately_on_error;
      exit_immediately_on_error = 0;

      run_startup_files ();
      exit_immediately_on_error += old_errexit_flag;
    }

  /* If we are invoked as `sh', turn on Posix mode. */
  if (act_like_sh)
    {
      bind_variable ("POSIXLY_CORRECT", "y", 0);
      sv_strict_posix ("POSIXLY_CORRECT");
    }

#if defined (RESTRICTED_SHELL)
  /* Turn on the restrictions after executing the startup files.  This
     means that `bash -r' or `set -r' invoked from a startup file will
     turn on the restrictions after the startup files are executed. */
  restricted = saverst || restricted;
  if (shell_reinitialized == 0)
    maybe_make_restricted (shell_name);
#endif /* RESTRICTED_SHELL */

#if defined (WORDEXP_OPTION)
  if (wordexp_only)
    {
      startup_state = 3;
      last_command_exit_value = run_wordexp (argv[top_level_arg_index]);
      exit_shell (last_command_exit_value);
    }
#endif

  cmd_init ();		/* initialize the command object caches */
  uwp_init ();

  if (command_execution_string)
    {
      startup_state = 2;

      if (debugging_mode)
	start_debugger ();

#if defined (ONESHOT)
      executing = 1;
      run_one_command (command_execution_string);
      exit_shell (last_command_exit_value);
#else /* ONESHOT */
      with_input_from_string (command_execution_string, "-c");
      goto read_and_execute;
#endif /* !ONESHOT */
    }

  /* Get possible input filename and set up default_buffered_input or
     default_input as appropriate. */
  if (shell_script_filename)
    open_shell_script (shell_script_filename);
  else if (interactive == 0)
    {
      /* In this mode, bash is reading a script from stdin, which is a
	 pipe or redirected file. */
#if defined (BUFFERED_INPUT)
      default_buffered_input = fileno (stdin);	/* == 0 */
#else
      setbuf (default_input, (char *)NULL);
#endif /* !BUFFERED_INPUT */
      read_from_stdin = 1;
    }
  else if (top_level_arg_index == argc)		/* arg index before startup files */
    /* "If there are no operands and the -c option is not specified, the -s
       option shall be assumed." */
    read_from_stdin = 1;

  set_bash_input ();

  if (debugging_mode && locally_skip_execution == 0 && running_setuid == 0 && (reading_shell_script || interactive_shell == 0))
    start_debugger ();

  /* Do the things that should be done only for interactive shells. */
  if (interactive_shell)
    {
      /* Set up for checking for presence of mail. */
      reset_mail_timer ();
      init_mail_dates ();

#if defined (HISTORY)
      /* Initialize the interactive history stuff. */
      bash_initialize_history ();
      /* Don't load the history from the history file if we've already
	 saved some lines in this session (e.g., by putting `history -s xx'
	 into one of the startup files). */
      if (shell_initialized == 0 && history_lines_this_session == 0)
	load_history ();
#endif /* HISTORY */

      /* Initialize terminal state for interactive shells after the
	 .bash_profile and .bashrc are interpreted. */
      get_tty_state ();
    }

#if !defined (ONESHOT)
 read_and_execute:
#endif /* !ONESHOT */

  shell_initialized = 1;

  if (pretty_print_mode && interactive_shell)
    {
      internal_warning (_("pretty-printing mode ignored in interactive shells"));
      pretty_print_mode = 0;
    }
  if (pretty_print_mode)
    exit_shell (pretty_print_loop ());

  /* Read commands until exit condition. */
  reader_loop ();
  exit_shell (last_command_exit_value);
}

static int
parse_long_options (argv, arg_start, arg_end)
     char **argv;
     int arg_start, arg_end;
{
  int arg_index, longarg, i;
  char *arg_string;

  arg_index = arg_start;
  while ((arg_index != arg_end) && (arg_string = argv[arg_index]) &&
	 (*arg_string == '-'))
    {
      longarg = 0;

      /* Make --login equivalent to -login. */
      if (arg_string[1] == '-' && arg_string[2])
	{
	  longarg = 1;
	  arg_string++;
	}

      for (i = 0; long_args[i].name; i++)
	{
	  if (STREQ (arg_string + 1, long_args[i].name))
	    {
	      if (long_args[i].type == Int)
		*long_args[i].int_value = 1;
	      else if (argv[++arg_index] == 0)
		{
		  report_error (_("%s: option requires an argument"), long_args[i].name);
		  exit (EX_BADUSAGE);
		}
	      else
		*long_args[i].char_value = argv[arg_index];

	      break;
	    }
	}
      if (long_args[i].name == 0)
	{
	  if (longarg)
	    {
	      report_error (_("%s: invalid option"), argv[arg_index]);
	      show_shell_usage (stderr, 0);
	      exit (EX_BADUSAGE);
	    }
	  break;		/* No such argument.  Maybe flag arg. */
	}

      arg_index++;
    }

  return (arg_index);
}

static int
parse_shell_options (argv, arg_start, arg_end)
     char **argv;
     int arg_start, arg_end;
{
  int arg_index;
  int arg_character, on_or_off, next_arg, i;
  char *o_option, *arg_string;

  arg_index = arg_start;
  while (arg_index != arg_end && (arg_string = argv[arg_index]) &&
	 (*arg_string == '-' || *arg_string == '+'))
    {
      /* There are flag arguments, so parse them. */
      next_arg = arg_index + 1;

      /* A single `-' signals the end of options.  From the 4.3 BSD sh.
	 An option `--' means the same thing; this is the standard
	 getopt(3) meaning. */
      if (arg_string[0] == '-' &&
	   (arg_string[1] == '\0' ||
	     (arg_string[1] == '-' && arg_string[2] == '\0')))
	return (next_arg);

      i = 1;
      on_or_off = arg_string[0];
      while (arg_character = arg_string[i++])
	{
	  switch (arg_character)
	    {
	    case 'c':
	      want_pending_command = 1;
	      break;

	    case 'l':
	      make_login_shell = 1;
	      break;

	    case 's':
	      read_from_stdin = 1;
	      break;

	    case 'o':
	      o_option = argv[next_arg];
	      if (o_option == 0)
		{
		  set_option_defaults ();
		  list_minus_o_opts (-1, (on_or_off == '-') ? 0 : 1);
		  reset_option_defaults ();
		  break;
		}
	      if (set_minus_o_option (on_or_off, o_option) != EXECUTION_SUCCESS)
		exit (EX_BADUSAGE);
	      next_arg++;
	      break;

	    case 'O':
	      /* Since some of these can be overridden by the normal
		 interactive/non-interactive shell initialization or
		 initializing posix mode, we save the options and process
		 them after initialization. */
	      o_option = argv[next_arg];
	      if (o_option == 0)
		{
		  shopt_listopt (o_option, (on_or_off == '-') ? 0 : 1);
		  break;
		}
	      add_shopt_to_alist (o_option, on_or_off);
	      next_arg++;
	      break;

	    case 'D':
	      dump_translatable_strings = 1;
	      break;

	    default:
	      if (change_flag (arg_character, on_or_off) == FLAG_ERROR)
		{
		  report_error (_("%c%c: invalid option"), on_or_off, arg_character);
		  show_shell_usage (stderr, 0);
		  exit (EX_BADUSAGE);
		}
	    }
	}
      /* Can't do just a simple increment anymore -- what about
	 "bash -abouo emacs ignoreeof -hP"? */
      arg_index = next_arg;
    }

  return (arg_index);
}

/* Exit the shell with status S. */
void
exit_shell (s)
     int s;
{
  fflush (stdout);		/* XXX */
  fflush (stderr);

  /* Clean up the terminal if we are in a state where it's been modified. */
#if defined (READLINE)
  if (RL_ISSTATE (RL_STATE_TERMPREPPED) && rl_deprep_term_function)
    (*rl_deprep_term_function) ();
#endif
  if (read_tty_modified ())
    read_tty_cleanup ();

  /* Do trap[0] if defined.  Allow it to override the exit status
     passed to us. */
  if (signal_is_trapped (0))
    s = run_exit_trap ();

#if defined (PROCESS_SUBSTITUTION)
  unlink_all_fifos ();
#endif /* PROCESS_SUBSTITUTION */

#if defined (HISTORY)
  if (remember_on_history)
    maybe_save_shell_history ();
#endif /* HISTORY */

#if defined (COPROCESS_SUPPORT)
  coproc_flush ();
#endif

#if defined (JOB_CONTROL)
  /* If the user has run `shopt -s huponexit', hangup all jobs when we exit
     an interactive login shell.  ksh does this unconditionally. */
  if (interactive_shell && login_shell && hup_on_exit)
    hangup_all_jobs ();

  /* If this shell is interactive, or job control is active, terminate all
     stopped jobs and restore the original terminal process group.  Don't do
     this if we're in a subshell and calling exit_shell after, for example,
     a failed word expansion.  We want to do this even if the shell is not
     interactive because we set the terminal's process group when job control
     is enabled regardless of the interactive status. */
  if (subshell_environment == 0)
    end_job_control ();
#endif /* JOB_CONTROL */

  /* Always return the exit status of the last command to our parent. */
  sh_exit (s);
}

/* A wrapper for exit that (optionally) can do other things, like malloc
   statistics tracing. */
void
sh_exit (s)
     int s;
{
#if defined (MALLOC_DEBUG) && defined (USING_BASH_MALLOC)
  if (malloc_trace_at_exit && (subshell_environment & (SUBSHELL_COMSUB|SUBSHELL_PROCSUB)) == 0)
    trace_malloc_stats (get_name_for_error (), (char *)NULL);
  /* mlocation_write_table (); */
#endif

  exit (s);
}

/* Exit a subshell, which includes calling the exit trap.  We don't want to
   do any more cleanup, since a subshell is created as an exact copy of its
   parent. */
void
subshell_exit (s)
     int s;
{
  fflush (stdout);
  fflush (stderr);

  /* Do trap[0] if defined.  Allow it to override the exit status
     passed to us. */
  if (signal_is_trapped (0))
    s = run_exit_trap ();

  sh_exit (s);
}

void
set_exit_status (s)
     int s;
{
  set_pipestatus_from_exit (last_command_exit_value = s);
}

/* Source the bash startup files.  If POSIXLY_CORRECT is non-zero, we obey
   the Posix.2 startup file rules:  $ENV is expanded, and if the file it
   names exists, that file is sourced.  The Posix.2 rules are in effect
   for interactive shells only. (section 4.56.5.3) */

/* Execute ~/.bashrc for most shells.  Never execute it if
   ACT_LIKE_SH is set, or if NO_RC is set.

   If the executable file "/usr/gnu/src/bash/foo" contains:

   #!/usr/gnu/bin/bash
   echo hello

   then:

	 COMMAND	    EXECUTE BASHRC
	 --------------------------------
	 bash -c foo		NO
	 bash foo		NO
	 foo			NO
	 rsh machine ls		YES (for rsh, which calls `bash -c')
	 rsh machine foo	YES (for shell started by rsh) NO (for foo!)
	 echo ls | bash		NO
	 login			NO
	 bash			YES
*/

static void
execute_env_file (env_file)
      char *env_file;
{
  char *fn;

  if (env_file && *env_file)
    {
      fn = expand_string_unsplit_to_string (env_file, Q_DOUBLE_QUOTES);
      if (fn && *fn)
	maybe_execute_file (fn, 1);
      FREE (fn);
    }
}

static void
run_startup_files ()
{
#if defined (JOB_CONTROL)
  int old_job_control;
#endif
  int sourced_login, run_by_ssh;

  /* get the rshd/sshd case out of the way first. */
  if (interactive_shell == 0 && no_rc == 0 && login_shell == 0 &&
      act_like_sh == 0 && command_execution_string)
    {
#ifdef SSH_SOURCE_BASHRC
      run_by_ssh = (find_variable ("SSH_CLIENT") != (SHELL_VAR *)0) ||
		   (find_variable ("SSH2_CLIENT") != (SHELL_VAR *)0);
#else
      run_by_ssh = 0;
#endif

      /* If we were run by sshd or we think we were run by rshd, execute
	 ~/.bashrc if we are a top-level shell. */
      if ((run_by_ssh || isnetconn (fileno (stdin))) && shell_level < 2)
	{
#ifdef SYS_BASHRC
#  if defined (__OPENNT)
	  maybe_execute_file (_prefixInstallPath(SYS_BASHRC, NULL, 0), 1);
#  else
	  maybe_execute_file (SYS_BASHRC, 1);
#  endif
#endif
	  maybe_execute_file (bashrc_file, 1);
	  return;
	}
    }

#if defined (JOB_CONTROL)
  /* Startup files should be run without job control enabled. */
  old_job_control = interactive_shell ? set_job_control (0) : 0;
#endif

  sourced_login = 0;

  /* A shell begun with the --login (or -l) flag that is not in posix mode
     runs the login shell startup files, no matter whether or not it is
     interactive.  If NON_INTERACTIVE_LOGIN_SHELLS is defined, run the
     startup files if argv[0][0] == '-' as well. */
#if defined (NON_INTERACTIVE_LOGIN_SHELLS)
  if (login_shell && posixly_correct == 0)
#else
  if (login_shell < 0 && posixly_correct == 0)
#endif
    {
      /* We don't execute .bashrc for login shells. */
      no_rc++;

      /* Execute /etc/profile and one of the personal login shell
	 initialization files. */
      if (no_profile == 0)
	{
	  maybe_execute_file (SYS_PROFILE, 1);

	  if (act_like_sh)	/* sh */
	    maybe_execute_file ("~/.profile", 1);
	  else if ((maybe_execute_file ("~/.bash_profile", 1) == 0) &&
		   (maybe_execute_file ("~/.bash_login", 1) == 0))	/* bash */
	    maybe_execute_file ("~/.profile", 1);
	}

      sourced_login = 1;
    }

  /* A non-interactive shell not named `sh' and not in posix mode reads and
     executes commands from $BASH_ENV.  If `su' starts a shell with `-c cmd'
     and `-su' as the name of the shell, we want to read the startup files.
     No other non-interactive shells read any startup files. */
  if (interactive_shell == 0 && !(su_shell && login_shell))
    {
      if (posixly_correct == 0 && act_like_sh == 0 && privileged_mode == 0 &&
	    sourced_env++ == 0)
	execute_env_file (get_string_value ("BASH_ENV"));
      return;
    }

  /* Interactive shell or `-su' shell. */
  if (posixly_correct == 0)		  /* bash, sh */
    {
      if (login_shell && sourced_login++ == 0)
	{
	  /* We don't execute .bashrc for login shells. */
	  no_rc++;

	  /* Execute /etc/profile and one of the personal login shell
	     initialization files. */
	  if (no_profile == 0)
	    {
	      maybe_execute_file (SYS_PROFILE, 1);

	      if (act_like_sh)	/* sh */
		maybe_execute_file ("~/.profile", 1);
	      else if ((maybe_execute_file ("~/.bash_profile", 1) == 0) &&
		       (maybe_execute_file ("~/.bash_login", 1) == 0))	/* bash */
		maybe_execute_file ("~/.profile", 1);
	    }
	}

      /* bash */
      if (act_like_sh == 0 && no_rc == 0)
	{
#ifdef SYS_BASHRC
#  if defined (__OPENNT)
	  maybe_execute_file (_prefixInstallPath(SYS_BASHRC, NULL, 0), 1);
#  else
	  maybe_execute_file (SYS_BASHRC, 1);
#  endif
#endif
	  maybe_execute_file (bashrc_file, 1);
	}
      /* sh */
      else if (act_like_sh && privileged_mode == 0 && sourced_env++ == 0)
	execute_env_file (get_string_value ("ENV"));
    }
  else		/* bash --posix, sh --posix */
    {
      /* bash and sh */
      if (interactive_shell && privileged_mode == 0 && sourced_env++ == 0)
	execute_env_file (get_string_value ("ENV"));
    }

#if defined (JOB_CONTROL)
  set_job_control (old_job_control);
#endif
}

#if defined (RESTRICTED_SHELL)
/* Return 1 if the shell should be a restricted one based on NAME or the
   value of `restricted'.  Don't actually do anything, just return a
   boolean value. */
int
shell_is_restricted (name)
     char *name;
{
  char *temp;

  if (restricted)
    return 1;
  temp = base_pathname (name);
  if (*temp == '-')
    temp++;
  return (STREQ (temp, RESTRICTED_SHELL_NAME));
}

/* Perhaps make this shell a `restricted' one, based on NAME.  If the
   basename of NAME is "rbash", then this shell is restricted.  The
   name of the restricted shell is a configurable option, see config.h.
   In a restricted shell, PATH, SHELL, ENV, and BASH_ENV are read-only
   and non-unsettable.
   Do this also if `restricted' is already set to 1; maybe the shell was
   started with -r. */
int
maybe_make_restricted (name)
     char *name;
{
  char *temp;

  temp = base_pathname (name);
  if (*temp == '-')
    temp++;
  if (restricted || (STREQ (temp, RESTRICTED_SHELL_NAME)))
    {
#if defined (RBASH_STATIC_PATH_VALUE)
      bind_variable ("PATH", RBASH_STATIC_PATH_VALUE, 0);
      stupidly_hack_special_variables ("PATH");		/* clear hash table */
#endif
      set_var_read_only ("PATH");
      set_var_read_only ("SHELL");
      set_var_read_only ("ENV");
      set_var_read_only ("BASH_ENV");
      set_var_read_only ("HISTFILE");
      restricted = 1;
    }
  return (restricted);
}
#endif /* RESTRICTED_SHELL */

/* Fetch the current set of uids and gids and return 1 if we're running
   setuid or setgid. */
static int
uidget ()
{
  uid_t u;

  u = getuid ();
  if (current_user.uid != u)
    {
      FREE (current_user.user_name);
      FREE (current_user.shell);
      FREE (current_user.home_dir);
      current_user.user_name = current_user.shell = current_user.home_dir = (char *)NULL;
    }
  current_user.uid = u;
  current_user.gid = getgid ();
  current_user.euid = geteuid ();
  current_user.egid = getegid ();

  /* See whether or not we are running setuid or setgid. */
  return (current_user.uid != current_user.euid) ||
	   (current_user.gid != current_user.egid);
}

void
disable_priv_mode ()
{
  int e;

#if HAVE_SETRESUID
  if (setresuid (current_user.uid, current_user.uid, current_user.uid) < 0)
#else
  if (setuid (current_user.uid) < 0)
#endif
    {
      e = errno;
      sys_error (_("cannot set uid to %d: effective uid %d"), current_user.uid, current_user.euid);
#if defined (EXIT_ON_SETUID_FAILURE)
      if (e == EAGAIN)
	exit (e);
#endif
    }
#if HAVE_SETRESGID
  if (setresgid (current_user.gid, current_user.gid, current_user.gid) < 0)
#else
  if (setgid (current_user.gid) < 0)
#endif
    sys_error (_("cannot set gid to %d: effective gid %d"), current_user.gid, current_user.egid);

  current_user.euid = current_user.uid;
  current_user.egid = current_user.gid;
}

#if defined (WORDEXP_OPTION)
static int
run_wordexp (words)
     char *words;
{
  int code, nw, nb;
  WORD_LIST *wl, *tl, *result;

  code = setjmp_nosigs (top_level);

  if (code != NOT_JUMPED)
    {
      switch (code)
	{
	  /* Some kind of throw to top_level has occurred. */
	case FORCE_EOF:
	  return last_command_exit_value = 127;
	case ERREXIT:
	case EXITPROG:
	  return last_command_exit_value;
	case DISCARD:
	  return last_command_exit_value = 1;
	default:
	  command_error ("run_wordexp", CMDERR_BADJUMP, code, 0);
	}
    }

  /* Run it through the parser to get a list of words and expand them */
  if (words && *words)
    {
      with_input_from_string (words, "--wordexp");
      if (parse_command () != 0)
	return (126);
      if (global_command == 0)
	{
	  printf ("0\n0\n");
	  return (0);
	}
      if (global_command->type != cm_simple)
	return (126);
      wl = global_command->value.Simple->words;
      if (protected_mode)
	for (tl = wl; tl; tl = tl->next)
	  tl->word->flags |= W_NOCOMSUB|W_NOPROCSUB;
      result = wl ? expand_words_no_vars (wl) : (WORD_LIST *)0;
    }
  else
    result = (WORD_LIST *)0;

  last_command_exit_value = 0;

  if (result == 0)
    {
      printf ("0\n0\n");
      return (0);
    }

  /* Count up the number of words and bytes, and print them.  Don't count
     the trailing NUL byte. */
  for (nw = nb = 0, wl = result; wl; wl = wl->next)
    {
      nw++;
      nb += strlen (wl->word->word);
    }
  printf ("%u\n%u\n", nw, nb);
  /* Print each word on a separate line.  This will have to be changed when
     the interface to glibc is completed. */
  for (wl = result; wl; wl = wl->next)
    printf ("%s\n", wl->word->word);

  return (0);
}
#endif

#if defined (ONESHOT)
/* Run one command, given as the argument to the -c option.  Tell
   parse_and_execute not to fork for a simple command. */
static int
run_one_command (command)
     char *command;
{
  int code;

  code = setjmp_nosigs (top_level);

  if (code != NOT_JUMPED)
    {
#if defined (PROCESS_SUBSTITUTION)
      unlink_fifo_list ();
#endif /* PROCESS_SUBSTITUTION */
      switch (code)
	{
	  /* Some kind of throw to top_level has occurred. */
	case FORCE_EOF:
	  return last_command_exit_value = 127;
	case ERREXIT:
	case EXITPROG:
	  return last_command_exit_value;
	case DISCARD:
	  return last_command_exit_value = 1;
	default:
	  command_error ("run_one_command", CMDERR_BADJUMP, code, 0);
	}
    }
   return (parse_and_execute (savestring (command), "-c", SEVAL_NOHIST|SEVAL_RESETLINE));
}
#endif /* ONESHOT */

static int
bind_args (argv, arg_start, arg_end, start_index)
     char **argv;
     int arg_start, arg_end, start_index;
{
  register int i;
  WORD_LIST *args, *tl;

  for (i = arg_start, args = tl = (WORD_LIST *)NULL; i < arg_end; i++)
    {
      if (args == 0)
	args = tl = make_word_list (make_word (argv[i]), args);
      else
	{
	  tl->next = make_word_list (make_word (argv[i]), (WORD_LIST *)NULL);
	  tl = tl->next;
	}
    }

  if (args)
    {
      if (start_index == 0)	/* bind to $0...$n for sh -c command */
	{
	  /* Posix.2 4.56.3 says that the first argument after sh -c command
	     becomes $0, and the rest of the arguments become $1...$n */
	  shell_name = savestring (args->word->word);
	  FREE (dollar_vars[0]);
	  dollar_vars[0] = savestring (args->word->word);
	  remember_args (args->next, 1);
	  if (debugging_mode)
	    {
	      push_args (args->next);	/* BASH_ARGV and BASH_ARGC */
	      bash_argv_initialized = 1;
	    }
	}
      else			/* bind to $1...$n for shell script */
        {
	  remember_args (args, 1);
	  /* We do this unconditionally so something like -O extdebug doesn't
	     do it first.  We're setting the definitive positional params
	     here. */
	  if (debugging_mode)
	    {
	      push_args (args);		/* BASH_ARGV and BASH_ARGC */
	      bash_argv_initialized = 1;
	    }
        }

      dispose_words (args);
    }

  return (i);
}

void
unbind_args ()
{
  remember_args ((WORD_LIST *)NULL, 1);
  pop_args ();				/* Reset BASH_ARGV and BASH_ARGC */
}

static void
start_debugger ()
{
#if defined (DEBUGGER) && defined (DEBUGGER_START_FILE)
  int old_errexit;
  int r;

  old_errexit = exit_immediately_on_error;
  exit_immediately_on_error = 0;

  r = force_execute_file (DEBUGGER_START_FILE, 1);
  if (r < 0)
    {
      internal_warning (_("cannot start debugger; debugging mode disabled"));
      debugging_mode = 0;
    }
  error_trace_mode = function_trace_mode = debugging_mode;

  set_shellopts ();
  set_bashopts ();

  exit_immediately_on_error += old_errexit;
#endif
}

static int
open_shell_script (script_name)
     char *script_name;
{
  int fd, e, fd_is_tty;
  char *filename, *path_filename, *t;
  char sample[80];
  int sample_len;
  struct stat sb;
#if defined (ARRAY_VARS)
  SHELL_VAR *funcname_v, *bash_source_v, *bash_lineno_v;
  ARRAY *funcname_a, *bash_source_a, *bash_lineno_a;
#endif

  filename = savestring (script_name);

  fd = open (filename, O_RDONLY);
  if ((fd < 0) && (errno == ENOENT) && (absolute_program (filename) == 0))
    {
      e = errno;
      /* If it's not in the current directory, try looking through PATH
	 for it. */
      path_filename = find_path_file (script_name);
      if (path_filename)
	{
	  free (filename);
	  filename = path_filename;
	  fd = open (filename, O_RDONLY);
	}
      else
	errno = e;
    }

  if (fd < 0)
    {
      e = errno;
      file_error (filename);
#if defined (JOB_CONTROL)
      end_job_control ();	/* just in case we were run as bash -i script */
#endif
      sh_exit ((e == ENOENT) ? EX_NOTFOUND : EX_NOINPUT);
    }

  free (dollar_vars[0]);
  dollar_vars[0] = exec_argv0 ? savestring (exec_argv0) : savestring (script_name);
  if (exec_argv0)
    {
      free (exec_argv0);
      exec_argv0 = (char *)NULL;
    }

  if (file_isdir (filename))
    {
#if defined (EISDIR)
      errno = EISDIR;
#else
      errno = EINVAL;
#endif
      file_error (filename);
#if defined (JOB_CONTROL)
      end_job_control ();	/* just in case we were run as bash -i script */
#endif
      sh_exit (EX_NOINPUT);
    }

#if defined (ARRAY_VARS)
  GET_ARRAY_FROM_VAR ("FUNCNAME", funcname_v, funcname_a);
  GET_ARRAY_FROM_VAR ("BASH_SOURCE", bash_source_v, bash_source_a);
  GET_ARRAY_FROM_VAR ("BASH_LINENO", bash_lineno_v, bash_lineno_a);

  array_push (bash_source_a, filename);
  if (bash_lineno_a)
    {
      t = itos (executing_line_number ());
      array_push (bash_lineno_a, t);
      free (t);
    }
  array_push (funcname_a, "main");
#endif

#ifdef HAVE_DEV_FD
  fd_is_tty = isatty (fd);
#else
  fd_is_tty = 0;
#endif

  /* Only do this with non-tty file descriptors we can seek on. */
  if (fd_is_tty == 0 && (lseek (fd, 0L, 1) != -1))
    {
      /* Check to see if the `file' in `bash file' is a binary file
	 according to the same tests done by execute_simple_command (),
	 and report an error and exit if it is. */
      sample_len = read (fd, sample, sizeof (sample));
      if (sample_len < 0)
	{
	  e = errno;
	  if ((fstat (fd, &sb) == 0) && S_ISDIR (sb.st_mode))
	    {
#if defined (EISDIR)
	      errno = EISDIR;
	      file_error (filename);
#else	      
	      internal_error (_("%s: Is a directory"), filename);
#endif
	    }
	  else
	    {
	      errno = e;
	      file_error (filename);
	    }
#if defined (JOB_CONTROL)
	  end_job_control ();	/* just in case we were run as bash -i script */
#endif
	  exit (EX_NOEXEC);
	}
      else if (sample_len > 0 && (check_binary_file (sample, sample_len)))
	{
	  internal_error (_("%s: cannot execute binary file"), filename);
#if defined (JOB_CONTROL)
	  end_job_control ();	/* just in case we were run as bash -i script */
#endif
	  exit (EX_BINARY_FILE);
	}
      /* Now rewind the file back to the beginning. */
      lseek (fd, 0L, 0);
    }

  /* Open the script.  But try to move the file descriptor to a randomly
     large one, in the hopes that any descriptors used by the script will
     not match with ours. */
  fd = move_to_high_fd (fd, 1, -1);

#if defined (BUFFERED_INPUT)
  default_buffered_input = fd;
  SET_CLOSE_ON_EXEC (default_buffered_input);
#else /* !BUFFERED_INPUT */
  default_input = fdopen (fd, "r");

  if (default_input == 0)
    {
      file_error (filename);
      exit (EX_NOTFOUND);
    }

  SET_CLOSE_ON_EXEC (fd);
  if (fileno (default_input) != fd)
    SET_CLOSE_ON_EXEC (fileno (default_input));
#endif /* !BUFFERED_INPUT */

  /* Just about the only way for this code to be executed is if something
     like `bash -i /dev/stdin' is executed. */
  if (interactive_shell && fd_is_tty)
    {
      dup2 (fd, 0);
      close (fd);
      fd = 0;
#if defined (BUFFERED_INPUT)
      default_buffered_input = 0;
#else
      fclose (default_input);
      default_input = stdin;
#endif
    }
  else if (forced_interactive && fd_is_tty == 0)
    /* But if a script is called with something like `bash -i scriptname',
       we need to do a non-interactive setup here, since we didn't do it
       before. */
    init_interactive_script ();

  free (filename);

  reading_shell_script = 1;
  return (fd);
}

/* Initialize the input routines for the parser. */
static void
set_bash_input ()
{
  /* Make sure the fd from which we are reading input is not in
     no-delay mode. */
#if defined (BUFFERED_INPUT)
  if (interactive == 0)
    sh_unset_nodelay_mode (default_buffered_input);
  else
#endif /* !BUFFERED_INPUT */
    sh_unset_nodelay_mode (fileno (stdin));

  /* with_input_from_stdin really means `with_input_from_readline' */
  if (interactive && no_line_editing == 0)
    with_input_from_stdin ();
#if defined (BUFFERED_INPUT)
  else if (interactive == 0)
    with_input_from_buffered_stream (default_buffered_input, dollar_vars[0]);
#endif /* BUFFERED_INPUT */
  else
    with_input_from_stream (default_input, dollar_vars[0]);
}

/* Close the current shell script input source and forget about it.  This is
   extern so execute_cmd.c:initialize_subshell() can call it.  If CHECK_ZERO
   is non-zero, we close default_buffered_input even if it's the standard
   input (fd 0). */
void
unset_bash_input (check_zero)
     int check_zero;
{
#if defined (BUFFERED_INPUT)
  if ((check_zero && default_buffered_input >= 0) ||
      (check_zero == 0 && default_buffered_input > 0))
    {
      close_buffered_fd (default_buffered_input);
      default_buffered_input = bash_input.location.buffered_fd = -1;
      bash_input.type = st_none;		/* XXX */
    }
#else /* !BUFFERED_INPUT */
  if (default_input)
    {
      fclose (default_input);
      default_input = (FILE *)NULL;
    }
#endif /* !BUFFERED_INPUT */
}
      

#if !defined (PROGRAM)
#  define PROGRAM "bash"
#endif

static void
set_shell_name (argv0)
     char *argv0;
{
  /* Here's a hack.  If the name of this shell is "sh", then don't do
     any startup files; just try to be more like /bin/sh. */
  shell_name = argv0 ? base_pathname (argv0) : PROGRAM;

  if (argv0 && *argv0 == '-')
    {
      if (*shell_name == '-')
	shell_name++;
      login_shell = 1;
    }

  if (shell_name[0] == 's' && shell_name[1] == 'h' && shell_name[2] == '\0')
    act_like_sh++;
  if (shell_name[0] == 's' && shell_name[1] == 'u' && shell_name[2] == '\0')
    su_shell++;

  shell_name = argv0 ? argv0 : PROGRAM;
  FREE (dollar_vars[0]);
  dollar_vars[0] = savestring (shell_name);

  /* A program may start an interactive shell with
	  "execl ("/bin/bash", "-", NULL)".
     If so, default the name of this shell to our name. */
  if (!shell_name || !*shell_name || (shell_name[0] == '-' && !shell_name[1]))
    shell_name = PROGRAM;
}

/* Some options are initialized to -1 so we have a way to determine whether
   they were set on the command line. This is an issue when listing the option
   values at invocation (`bash -o'), so we set the defaults here and reset
   them after the call to list_minus_o_options (). */
/* XXX - could also do this for histexp_flag, jobs_m_flag */
static void
set_option_defaults ()
{
#if defined (HISTORY)
  enable_history_list = 0;
#endif
}

static void
reset_option_defaults ()
{
#if defined (HISTORY)
  enable_history_list = -1;
#endif
}

static void
init_interactive ()
{
  expand_aliases = interactive_shell = startup_state = 1;
  interactive = 1;
#if defined (HISTORY)
  if (enable_history_list == -1)
    enable_history_list = 1;				/* set default  */
  remember_on_history = enable_history_list;
#  if defined (BANG_HISTORY)
  histexp_flag = history_expansion;			/* XXX */
#  endif
#endif
}

static void
init_noninteractive ()
{
#if defined (HISTORY)
  if (enable_history_list == -1)			/* set default */
    enable_history_list = 0;
  bash_history_reinit (0);
#endif /* HISTORY */
  interactive_shell = startup_state = interactive = 0;
  expand_aliases = posixly_correct;	/* XXX - was 0 not posixly_correct */
  no_line_editing = 1;
#if defined (JOB_CONTROL)
  /* Even if the shell is not interactive, enable job control if the -i or
     -m option is supplied at startup. */
  set_job_control (forced_interactive||jobs_m_flag);
#endif /* JOB_CONTROL */
}

static void
init_interactive_script ()
{
#if defined (HISTORY)
  if (enable_history_list == -1)
    enable_history_list = 1;
#endif
  init_noninteractive ();
  expand_aliases = interactive_shell = startup_state = 1;
#if defined (HISTORY)
  remember_on_history = enable_history_list;	/* XXX */
#endif
}

void
get_current_user_info ()
{
  struct passwd *entry;

  /* Don't fetch this more than once. */
  if (current_user.user_name == 0)
    {
#if defined (__TANDEM)
      entry = getpwnam (getlogin ());
#else
      entry = getpwuid (current_user.uid);
#endif
      if (entry)
	{
	  current_user.user_name = savestring (entry->pw_name);
	  current_user.shell = (entry->pw_shell && entry->pw_shell[0])
				? savestring (entry->pw_shell)
				: savestring ("/bin/sh");
	  current_user.home_dir = savestring (entry->pw_dir);
	}
      else
	{
	  current_user.user_name = _("I have no name!");
	  current_user.user_name = savestring (current_user.user_name);
	  current_user.shell = savestring ("/bin/sh");
	  current_user.home_dir = savestring ("/");
	}
#if defined (HAVE_GETPWENT)
      endpwent ();
#endif
    }
}

/* Do whatever is necessary to initialize the shell.
   Put new initializations in here. */
static void
shell_initialize ()
{
  char hostname[256];
  int should_be_restricted;

  /* Line buffer output for stderr and stdout. */
  if (shell_initialized == 0)
    {
      sh_setlinebuf (stderr);
      sh_setlinebuf (stdout);
    }

  /* Sort the array of shell builtins so that the binary search in
     find_shell_builtin () works correctly. */
  initialize_shell_builtins ();

  /* Initialize the trap signal handlers before installing our own
     signal handlers.  traps.c:restore_original_signals () is responsible
     for restoring the original default signal handlers.  That function
     is called when we make a new child. */
  initialize_traps ();
  initialize_signals (0);

  /* It's highly unlikely that this will change. */
  if (current_host_name == 0)
    {
      /* Initialize current_host_name. */
      if (gethostname (hostname, 255) < 0)
	current_host_name = "??host??";
      else
	current_host_name = savestring (hostname);
    }

  /* Initialize the stuff in current_user that comes from the password
     file.  We don't need to do this right away if the shell is not
     interactive. */
  if (interactive_shell)
    get_current_user_info ();

  /* Initialize our interface to the tilde expander. */
  tilde_initialize ();

#if defined (RESTRICTED_SHELL)
  should_be_restricted = shell_is_restricted (shell_name);
#endif

  /* Initialize internal and environment variables.  Don't import shell
     functions from the environment if we are running in privileged or
     restricted mode or if the shell is running setuid. */
#if defined (RESTRICTED_SHELL)
  initialize_shell_variables (shell_environment, privileged_mode||restricted||should_be_restricted||running_setuid);
#else
  initialize_shell_variables (shell_environment, privileged_mode||running_setuid);
#endif

  /* Initialize the data structures for storing and running jobs. */
  initialize_job_control (jobs_m_flag);

  /* Initialize input streams to null. */
  initialize_bash_input ();

  initialize_flags ();

  /* Initialize the shell options.  Don't import the shell options
     from the environment variables $SHELLOPTS or $BASHOPTS if we are
     running in privileged or restricted mode or if the shell is running
     setuid. */
#if defined (RESTRICTED_SHELL)
  initialize_shell_options (privileged_mode||restricted||should_be_restricted||running_setuid);
  initialize_bashopts (privileged_mode||restricted||should_be_restricted||running_setuid);
#else
  initialize_shell_options (privileged_mode||running_setuid);
  initialize_bashopts (privileged_mode||running_setuid);
#endif
}

/* Function called by main () when it appears that the shell has already
   had some initialization performed.  This is supposed to reset the world
   back to a pristine state, as if we had been exec'ed. */
static void
shell_reinitialize ()
{
  /* The default shell prompts. */
  primary_prompt = PPROMPT;
  secondary_prompt = SPROMPT;

  /* Things that get 1. */
  current_command_number = 1;

  /* We have decided that the ~/.bashrc file should not be executed
     for the invocation of each shell script.  If the variable $ENV
     (or $BASH_ENV) is set, its value is used as the name of a file
     to source. */
  no_rc = no_profile = 1;

  /* Things that get 0. */
  login_shell = make_login_shell = interactive = executing = 0;
  debugging = do_version = line_number = last_command_exit_value = 0;
  forced_interactive = interactive_shell = 0;
  subshell_environment = running_in_background = 0;
  expand_aliases = 0;
  bash_argv_initialized = 0;

  /* XXX - should we set jobs_m_flag to 0 here? */

#if defined (HISTORY)
  bash_history_reinit (enable_history_list = 0);
#endif /* HISTORY */

#if defined (RESTRICTED_SHELL)
  restricted = 0;
#endif /* RESTRICTED_SHELL */

  /* Ensure that the default startup file is used.  (Except that we don't
     execute this file for reinitialized shells). */
  bashrc_file = DEFAULT_BASHRC;

  /* Delete all variables and functions.  They will be reinitialized when
     the environment is parsed. */
  delete_all_contexts (shell_variables);
  delete_all_variables (shell_functions);

  reinit_special_variables ();

#if defined (READLINE)
  bashline_reinitialize ();
#endif

  shell_reinitialized = 1;
}

static void
show_shell_usage (fp, extra)
     FILE *fp;
     int extra;
{
  int i;
  char *set_opts, *s, *t;

  if (extra)
    fprintf (fp, _("GNU bash, version %s-(%s)\n"), shell_version_string (), MACHTYPE);
  fprintf (fp, _("Usage:\t%s [GNU long option] [option] ...\n\t%s [GNU long option] [option] script-file ...\n"),
	     shell_name, shell_name);
  fputs (_("GNU long options:\n"), fp);
  for (i = 0; long_args[i].name; i++)
    fprintf (fp, "\t--%s\n", long_args[i].name);

  fputs (_("Shell options:\n"), fp);
  fputs (_("\t-ilrsD or -c command or -O shopt_option\t\t(invocation only)\n"), fp);

  for (i = 0, set_opts = 0; shell_builtins[i].name; i++)
    if (STREQ (shell_builtins[i].name, "set"))
      {
	set_opts = savestring (shell_builtins[i].short_doc);
	break;
      }

  if (set_opts)
    {
      s = strchr (set_opts, '[');
      if (s == 0)
	s = set_opts;
      while (*++s == '-')
	;
      t = strchr (s, ']');
      if (t)
	*t = '\0';
      fprintf (fp, _("\t-%s or -o option\n"), s);
      free (set_opts);
    }

  if (extra)
    {
      fprintf (fp, _("Type `%s -c \"help set\"' for more information about shell options.\n"), shell_name);
      fprintf (fp, _("Type `%s -c help' for more information about shell builtin commands.\n"), shell_name);
      fprintf (fp, _("Use the `bashbug' command to report bugs.\n"));
      fprintf (fp, "\n");
      fprintf (fp, _("bash home page: <http://www.gnu.org/software/bash>\n"));
      fprintf (fp, _("General help using GNU software: <http://www.gnu.org/gethelp/>\n"));
    }
}

static void
add_shopt_to_alist (opt, on_or_off)
     char *opt;
     int on_or_off;
{
  if (shopt_ind >= shopt_len)
    {
      shopt_len += 8;
      shopt_alist = (STRING_INT_ALIST *)xrealloc (shopt_alist, shopt_len * sizeof (shopt_alist[0]));
    }
  shopt_alist[shopt_ind].word = opt;
  shopt_alist[shopt_ind].token = on_or_off;
  shopt_ind++;
}

static void
run_shopt_alist ()
{
  register int i;

  for (i = 0; i < shopt_ind; i++)
    if (shopt_setopt (shopt_alist[i].word, (shopt_alist[i].token == '-')) != EXECUTION_SUCCESS)
      exit (EX_BADUSAGE);
  free (shopt_alist);
  shopt_alist = 0;
  shopt_ind = shopt_len = 0;
}