binutils-gdb/gdb/main.c

/* Top level `main' program for GDB, the GNU debugger.
   Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992
   Free Software Foundation, Inc.

This file is part of GDB.

This program 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 of the License, or
(at your option) any later version.

This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"
#include "gdbcmd.h"
#include "call-cmds.h"
#include "symtab.h"
#include "inferior.h"
#include "signals.h"
#include "target.h"
#include "breakpoint.h"
#include "gdbtypes.h"
#include "expression.h"
#include "language.h"
#include "serial.h" /* For job_control.  */

#include "getopt.h"

/* readline include files */
#include "readline.h"
#include "history.h"

/* readline defines this.  */
#undef savestring

#ifdef USG
#include <sys/types.h>
#include <unistd.h>
#endif

#include <string.h>
#ifndef	NO_SYS_FILE
#include <sys/file.h>
#endif
#include <setjmp.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <ctype.h>

#ifdef SET_STACK_LIMIT_HUGE
#include <sys/time.h>
#include <sys/resource.h>

int original_stack_limit;
#endif

/* Prototypes for local functions */

static char *
symbol_completion_function PARAMS ((char *, int));

static void
command_loop PARAMS ((void));

static void
command_loop_marker PARAMS ((int));

static void
print_gdb_version PARAMS ((FILE *));

static void
quit_command PARAMS ((char *, int));

static void
init_main PARAMS ((void));

static void
init_history PARAMS ((void));

static void
init_cmd_lists PARAMS ((void));

static void
float_handler PARAMS ((int));

static void
source_command PARAMS ((char *, int));

static void cd_command PARAMS ((char *, int));

static void
print_gnu_advertisement PARAMS ((void));

static void
init_signals PARAMS ((void));

static void
read_command_file PARAMS ((FILE *));

static void 
set_verbose PARAMS ((char *, int, struct cmd_list_element *));

static void
show_history PARAMS ((char *, int));

static void
set_history PARAMS ((char *, int));

static void
set_history_size_command PARAMS ((char *, int, struct cmd_list_element *));

static void
show_commands PARAMS ((char *, int));

static void
echo_command PARAMS ((char *, int));

static void
pwd_command PARAMS ((char *, int));

static void
show_version PARAMS ((char *, int));

static void
document_command PARAMS ((char *, int));

static void
define_command PARAMS ((char *, int));

static void
validate_comname PARAMS ((char *));

static void
help_command PARAMS ((char *, int));

static void
show_command PARAMS ((char *, int));

static void
info_command PARAMS ((char *, int));

static void
do_nothing PARAMS ((int));

static int
quit_cover PARAMS ((char *));

static void
disconnect PARAMS ((int));

static void
source_cleanup PARAMS ((FILE *));

/* If this definition isn't overridden by the header files, assume
   that isatty and fileno exist on this system.  */
#ifndef ISATTY
#define ISATTY(FP)	(isatty (fileno (FP)))
#endif

/* Initialization file name for gdb.  This is overridden in some configs.  */

#ifndef	GDBINIT_FILENAME
#define	GDBINIT_FILENAME	".gdbinit"
#endif
static char gdbinit[] = GDBINIT_FILENAME;
static int inhibit_gdbinit = 0;

#define	ALL_CLEANUPS	((struct cleanup *)0)

/* Version number of GDB, as a string.  */

extern char *version;

/* Canonical host name as a string. */

extern char *host_canonical;

/* Canonical target name as a string. */

extern char *target_canonical;

/* Message to be printed before the error message, when an error occurs.  */

extern char *error_pre_print;

/* Message to be printed before the warning message, when a warning occurs.  */

extern char *warning_pre_print;

extern char lang_frame_mismatch_warn[];		/* language.c */

/* Flag for whether we want all the "from_tty" gubbish printed.  */

int caution = 1;			/* Default is yes, sigh. */

/*
 * Define all cmd_list_element's
 */

/* Chain containing all defined commands.  */

struct cmd_list_element *cmdlist;

/* Chain containing all defined info subcommands.  */

struct cmd_list_element *infolist;

/* Chain containing all defined enable subcommands. */

struct cmd_list_element *enablelist;

/* Chain containing all defined disable subcommands. */

struct cmd_list_element *disablelist;

/* Chain containing all defined delete subcommands. */

struct cmd_list_element *deletelist;

/* Chain containing all defined "enable breakpoint" subcommands. */

struct cmd_list_element *enablebreaklist;

/* Chain containing all defined set subcommands */

struct cmd_list_element *setlist;

/* Chain containing all defined unset subcommands */

struct cmd_list_element *unsetlist;

/* Chain containing all defined show subcommands.  */

struct cmd_list_element *showlist;

/* Chain containing all defined \"set history\".  */

struct cmd_list_element *sethistlist;

/* Chain containing all defined \"show history\".  */

struct cmd_list_element *showhistlist;

/* Chain containing all defined \"unset history\".  */

struct cmd_list_element *unsethistlist;

/* Chain containing all defined maintenance subcommands. */

#if MAINTENANCE_CMDS
struct cmd_list_element *maintenancelist;
#endif

/* Chain containing all defined "maintenance info" subcommands. */

#if MAINTENANCE_CMDS
struct cmd_list_element *maintenanceinfolist;
#endif

/* Chain containing all defined "maintenance print" subcommands. */

#if MAINTENANCE_CMDS
struct cmd_list_element *maintenanceprintlist;
#endif

struct cmd_list_element *setprintlist;

struct cmd_list_element *showprintlist;

struct cmd_list_element *setchecklist;

struct cmd_list_element *showchecklist;

/* stdio stream that command input is being read from.  */

FILE *instream;

/* Current working directory.  */

char *current_directory;

/* The directory name is actually stored here (usually).  */
static char dirbuf[1024];

/* Function to call before reading a command, if nonzero.
   The function receives two args: an input stream,
   and a prompt string.  */

void (*window_hook) PARAMS ((FILE *, char *));

extern int mapped_symbol_files;
extern int readnow_symbol_files;

int epoch_interface;
int xgdb_verbose;

/* gdb prints this when reading a command interactively */
static char *prompt;

/* Buffer used for reading command lines, and the size
   allocated for it so far.  */

char *line;
int linesize = 100;

/* Baud rate specified for talking to serial target systems.  Default
   is left as a zero pointer, so targets can choose their own defaults.  */

char *baud_rate;

/* Signal to catch ^Z typed while reading a command: SIGTSTP or SIGCONT.  */

#ifndef STOP_SIGNAL
#ifdef SIGTSTP
#define STOP_SIGNAL SIGTSTP
static void stop_sig PARAMS ((int));
#endif
#endif

/* Some System V have job control but not sigsetmask(). */
#if !defined (HAVE_SIGSETMASK)
#define HAVE_SIGSETMASK !defined (USG)
#endif

#if 0 == (HAVE_SIGSETMASK)
#define sigsetmask(n)
#endif

/* Where to go for return_to_top_level (RETURN_ERROR).  */
static jmp_buf error_return;
/* Where to go for return_to_top_level (RETURN_QUIT).  */
static jmp_buf quit_return;

/* Temporary variable for SET_TOP_LEVEL.  */
static int top_level_val;

/* Do a setjmp on error_return and quit_return.  catch_errors is
   generally a cleaner way to do this, but main() would look pretty
   ugly if it had to use catch_errors each time.  */

#define SET_TOP_LEVEL() \
  (((top_level_val = setjmp (error_return)) \
    ? (PTR) 0 : (PTR) memcpy (quit_return, error_return, sizeof (jmp_buf))) \
   , top_level_val)

/* Return for reason REASON.  This generally gets back to the command
   loop, but can be caught via catch_errors.  */

NORETURN void
return_to_top_level (reason)
     enum return_reason reason;
{
  quit_flag = 0;
  immediate_quit = 0;

  /* Perhaps it would be cleaner to do this via the cleanup chain (not sure
     I can think of a reason why that is vital, though).  */
  bpstat_clear_actions(stop_bpstat);	/* Clear queued breakpoint commands */

  disable_current_display ();
  do_cleanups (ALL_CLEANUPS);
  (NORETURN void) longjmp
    (reason == RETURN_ERROR ? error_return : quit_return, 1);
}

/* Call FUNC with arg ARGS, catching any errors.  If there is no
   error, return the value returned by FUNC.  If there is an error,
   print ERRSTRING, print the specific error message, then return
   zero.

   MASK specifies what to catch; it is normally set to
   RETURN_MASK_ALL, if for no other reason than that the code which
   calls catch_errors might not be set up to deal with a quit which
   isn't caught.  But if the code can deal with it, it generally
   should be RETURN_MASK_ERROR, unless for some reason it is more
   useful to abort only the portion of the operation inside the
   catch_errors.  Note that quit should return to the command line
   fairly quickly, even if some further processing is being done.  */

int
catch_errors (func, args, errstring, mask)
     int (*func) PARAMS ((char *));
     PTR args;
     char *errstring;
     return_mask mask;
{
  jmp_buf saved_error;
  jmp_buf saved_quit;
  jmp_buf tmp_jmp;
  int val;
  struct cleanup *saved_cleanup_chain;
  char *saved_error_pre_print;

  saved_cleanup_chain = save_cleanups ();
  saved_error_pre_print = error_pre_print;

  if (mask & RETURN_MASK_ERROR)
    memcpy ((char *)saved_error, (char *)error_return, sizeof (jmp_buf));
  if (mask & RETURN_MASK_QUIT)
    memcpy (saved_quit, quit_return, sizeof (jmp_buf));
  error_pre_print = errstring;

  if (setjmp (tmp_jmp) == 0)
    {
      if (mask & RETURN_MASK_ERROR)
	memcpy (error_return, tmp_jmp, sizeof (jmp_buf));
      if (mask & RETURN_MASK_QUIT)
	memcpy (quit_return, tmp_jmp, sizeof (jmp_buf));
      val = (*func) (args);
    }
  else
    val = 0;

  restore_cleanups (saved_cleanup_chain);

  error_pre_print = saved_error_pre_print;
  if (mask & RETURN_MASK_ERROR)
    memcpy (error_return, saved_error, sizeof (jmp_buf));
  if (mask & RETURN_MASK_QUIT)
    memcpy (quit_return, saved_quit, sizeof (jmp_buf));
  return val;
}

/* Handler for SIGHUP.  */

static void
disconnect (signo)
int signo;
{
  catch_errors (quit_cover, NULL,
		"Could not kill the program being debugged", RETURN_MASK_ALL);
  signal (SIGHUP, SIG_DFL);
  kill (getpid (), SIGHUP);
}

/* Just a little helper function for disconnect().  */

static int
quit_cover (s)
char *s;
{
  caution = 0;		/* Throw caution to the wind -- we're exiting.
			   This prevents asking the user dumb questions.  */
  quit_command((char *)0, 0);
  return 0;
}

/* Clean up on error during a "source" command (or execution of a
   user-defined command).  */

static void
source_cleanup (stream)
     FILE *stream;
{
  /* Restore the previous input stream.  */
  instream = stream;
}

/* Read commands from STREAM.  */
static void
read_command_file (stream)
     FILE *stream;
{
  struct cleanup *cleanups;

  cleanups = make_cleanup (source_cleanup, instream);
  instream = stream;
  command_loop ();
  do_cleanups (cleanups);
}

int
main (argc, argv)
     int argc;
     char **argv;
{
  int count;
  static int quiet = 0;
  static int batch = 0;

  /* Pointers to various arguments from command line.  */
  char *symarg = NULL;
  char *execarg = NULL;
  char *corearg = NULL;
  char *cdarg = NULL;
  char *ttyarg = NULL;

  /* These are static so that we can take their address in an initializer.  */
  static int print_help;
  static int print_version;

  /* Pointers to all arguments of --command option.  */
  char **cmdarg;
  /* Allocated size of cmdarg.  */
  int cmdsize;
  /* Number of elements of cmdarg used.  */
  int ncmd;

  /* Indices of all arguments of --directory option.  */
  char **dirarg;
  /* Allocated size.  */
  int dirsize;
  /* Number of elements used.  */
  int ndir;
  
  struct stat homebuf, cwdbuf;
  char *homedir, *homeinit;

  register int i;

  /* This needs to happen before the first use of malloc.  */
  init_malloc ((PTR) NULL);

#if defined (ALIGN_STACK_ON_STARTUP)
  i = (int) &count & 0x3;
  if (i != 0)
    alloca (4 - i);
#endif

  /* If error() is called from initialization code, just exit */
  if (SET_TOP_LEVEL ()) {
    exit(1);
  }

  cmdsize = 1;
  cmdarg = (char **) xmalloc (cmdsize * sizeof (*cmdarg));
  ncmd = 0;
  dirsize = 1;
  dirarg = (char **) xmalloc (dirsize * sizeof (*dirarg));
  ndir = 0;

  quit_flag = 0;
  line = (char *) xmalloc (linesize);
  line[0] = '\0';		/* Terminate saved (now empty) cmd line */
  instream = stdin;

  getcwd (dirbuf, sizeof (dirbuf));
  current_directory = dirbuf;

#ifdef SET_STACK_LIMIT_HUGE
  {
    struct rlimit rlim;

    /* Set the stack limit huge so that alloca (particularly stringtab
     * in dbxread.c) does not fail. */
    getrlimit (RLIMIT_STACK, &rlim);
    original_stack_limit = rlim.rlim_cur;
    rlim.rlim_cur = rlim.rlim_max;
    setrlimit (RLIMIT_STACK, &rlim);
  }
#endif /* SET_STACK_LIMIT_HUGE */

  /* Parse arguments and options.  */
  {
    int c;
    /* When var field is 0, use flag field to record the equivalent
       short option (or arbitrary numbers starting at 10 for those
       with no equivalent).  */
    static struct option long_options[] =
      {
	{"readnow", no_argument, &readnow_symbol_files, 1},
	{"r", no_argument, &readnow_symbol_files, 1},
	{"mapped", no_argument, &mapped_symbol_files, 1},
	{"m", no_argument, &mapped_symbol_files, 1},
	{"quiet", no_argument, &quiet, 1},
	{"q", no_argument, &quiet, 1},
	{"silent", no_argument, &quiet, 1},
	{"nx", no_argument, &inhibit_gdbinit, 1},
	{"n", no_argument, &inhibit_gdbinit, 1},
	{"batch", no_argument, &batch, 1},
	{"epoch", no_argument, &epoch_interface, 1},
	{"fullname", no_argument, &frame_file_full_name, 1},
	{"f", no_argument, &frame_file_full_name, 1},
	{"help", no_argument, &print_help, 1},
	{"se", required_argument, 0, 10},
	{"symbols", required_argument, 0, 's'},
	{"s", required_argument, 0, 's'},
	{"exec", required_argument, 0, 'e'},
	{"e", required_argument, 0, 'e'},
	{"core", required_argument, 0, 'c'},
	{"c", required_argument, 0, 'c'},
	{"command", required_argument, 0, 'x'},
	{"version", no_argument, &print_version, 1},
	{"x", required_argument, 0, 'x'},
	{"directory", required_argument, 0, 'd'},
	{"cd", required_argument, 0, 11},
	{"tty", required_argument, 0, 't'},
	{"baud", required_argument, 0, 'b'},
	{"b", required_argument, 0, 'b'},
/* Allow machine descriptions to add more options... */
#ifdef ADDITIONAL_OPTIONS
	ADDITIONAL_OPTIONS
#endif
	{0, no_argument, 0, 0},
      };

    while (1)
      {
	int option_index;

	c = getopt_long_only (argc, argv, "",
			      long_options, &option_index);
	if (c == EOF)
	  break;

	/* Long option that takes an argument.  */
	if (c == 0 && long_options[option_index].flag == 0)
	  c = long_options[option_index].val;

	switch (c)
	  {
	  case 0:
	    /* Long option that just sets a flag.  */
	    break;
	  case 10:
	    symarg = optarg;
	    execarg = optarg;
	    break;
	  case 11:
	    cdarg = optarg;
	    break;
	  case 's':
	    symarg = optarg;
	    break;
	  case 'e':
	    execarg = optarg;
	    break;
	  case 'c':
	    corearg = optarg;
	    break;
	  case 'x':
	    cmdarg[ncmd++] = optarg;
	    if (ncmd >= cmdsize)
	      {
		cmdsize *= 2;
		cmdarg = (char **) xrealloc ((char *)cmdarg,
					     cmdsize * sizeof (*cmdarg));
	      }
	    break;
	  case 'd':
	    dirarg[ndir++] = optarg;
	    if (ndir >= dirsize)
	      {
		dirsize *= 2;
		dirarg = (char **) xrealloc ((char *)dirarg,
					     dirsize * sizeof (*dirarg));
	      }
	    break;
	  case 't':
	    ttyarg = optarg;
	    break;
	  case 'q':
	    quiet = 1;
	    break;
	  case 'b':
	    baud_rate = optarg;
	    break;
#ifdef ADDITIONAL_OPTION_CASES
	  ADDITIONAL_OPTION_CASES
#endif
	  case '?':
	    fprintf (stderr,
		     "Use `%s --help' for a complete list of options.\n",
		     argv[0]);
	    exit (1);
	  }
      }

    /* OK, that's all the options.  The other arguments are filenames.  */
    count = 0;
    for (; optind < argc; optind++)
      switch (++count)
	{
	case 1:
	  symarg = argv[optind];
	  execarg = argv[optind];
	  break;
	case 2:
	  corearg = argv[optind];
	  break;
	case 3:
	  fprintf (stderr,
		   "Excess command line arguments ignored. (%s%s)\n",
		   argv[optind], (optind == argc - 1) ? "" : " ...");
	  break;
	}
    if (batch)
      quiet = 1;
  }

  /* Run the init function of each source file */

  init_cmd_lists ();	/* This needs to be done first */
  initialize_all_files ();
  init_main ();		/* But that omits this file!  Do it now */
  init_signals ();

  /* Do these (and anything which might call wrap_here or *_filtered)
     after initialize_all_files.  */
  if (print_version)
    {
      print_gdb_version (stdout);
      wrap_here ("");
      printf_filtered ("\n");
      exit (0);
    }

  if (print_help)
    {
      /* --version is intentionally not documented here, because we
	 are printing the version here, and the help is long enough
	 already.  */

      print_gdb_version (stdout);
      /* Make sure the output gets printed.  */
      wrap_here ("");
      printf_filtered ("\n");

      /* But don't use *_filtered here.  We don't want to prompt for continue
	 no matter how small the screen or how much we're going to print.  */
      fputs ("\
This is the GNU debugger.  Usage:\n\
    gdb [options] [executable-file [core-file or process-id]]\n\
Options:\n\
  --help             Print this message.\n\
  --quiet            Do not print version number on startup.\n\
  --fullname         Output information used by emacs-GDB interface.\n\
  --epoch            Output information used by epoch emacs-GDB interface.\n\
  --batch            Exit after processing options.\n\
  --nx               Do not read .gdbinit file.\n\
  --tty=TTY          Use TTY for input/output by the program being debugged.\n\
  --cd=DIR           Change current directory to DIR.\n\
  --directory=DIR    Search for source files in DIR.\n\
  --command=FILE     Execute GDB commands from FILE.\n\
  --symbols=SYMFILE  Read symbols from SYMFILE.\n\
  --exec=EXECFILE    Use EXECFILE as the executable.\n\
  --se=FILE          Use FILE as symbol file and executable file.\n\
  --core=COREFILE    Analyze the core dump COREFILE.\n\
  -b BAUDRATE        Set serial port baud rate used for remote debugging.\n\
  --mapped           Use mapped symbol files if supported on this system.\n\
  --readnow          Fully read symbol files on first access.\n\
", stdout);
#ifdef ADDITIONAL_OPTION_HELP
      fputs (ADDITIONAL_OPTION_HELP, stdout);
#endif
      fputs ("\n\
For more information, type \"help\" from within GDB, or consult the\n\
GDB manual (available as on-line info or a printed manual).\n", stdout);
      exit (0);
    }
    
  if (!quiet)
    {
      /* Print all the junk at the top, with trailing "..." if we are about
	 to read a symbol file (possibly slowly).  */
      print_gnu_advertisement ();
      print_gdb_version (stdout);
      if (symarg)
	printf_filtered ("..");
      wrap_here("");
      fflush (stdout);		/* Force to screen during slow operations */
    }

  error_pre_print = "\n\n";
  /* We may get more than one warning, don't double space all of them... */
  warning_pre_print = "\nwarning: ";

  /* We need a default language for parsing expressions, so simple things like
     "set width 0" won't fail if no language is explicitly set in a config file
     or implicitly set by reading an executable during startup. */
  set_language (language_c);
  expected_language = current_language;	/* don't warn about the change.  */

  /* Read and execute $HOME/.gdbinit file, if it exists.  This is done
     *before* all the command line arguments are processed; it sets
     global parameters, which are independent of what file you are
     debugging or what directory you are in.  */
  homedir = getenv ("HOME");
  if (homedir)
    {
      homeinit = (char *) alloca (strlen (getenv ("HOME")) +
				  strlen (gdbinit) + 10);
      strcpy (homeinit, getenv ("HOME"));
      strcat (homeinit, "/");
      strcat (homeinit, gdbinit);
      if (!inhibit_gdbinit && access (homeinit, R_OK) == 0)
	{
	  if (!SET_TOP_LEVEL ())
	    source_command (homeinit, 0);
	}
      do_cleanups (ALL_CLEANUPS);

      /* Do stats; no need to do them elsewhere since we'll only
	 need them if homedir is set.  Make sure that they are
	 zero in case one of them fails (this guarantees that they
	 won't match if either exists).  */
      
      memset (&homebuf, 0, sizeof (struct stat));
      memset (&cwdbuf, 0, sizeof (struct stat));
      
      stat (homeinit, &homebuf);
      stat (gdbinit, &cwdbuf); /* We'll only need this if
				       homedir was set.  */
    }
  
  /* Now perform all the actions indicated by the arguments.  */
  if (cdarg != NULL)
    {
      if (!SET_TOP_LEVEL ())
	{
	  cd_command (cdarg, 0);
	  init_source_path ();
	}
    }
  do_cleanups (ALL_CLEANUPS);

  for (i = 0; i < ndir; i++)
    if (!SET_TOP_LEVEL ())
      directory_command (dirarg[i], 0);
  free ((PTR)dirarg);
  do_cleanups (ALL_CLEANUPS);

  if (execarg != NULL
      && symarg != NULL
      && STREQ (execarg, symarg))
    {
      /* The exec file and the symbol-file are the same.  If we can't open
	 it, better only print one error message.  */
      if (!SET_TOP_LEVEL ())
	{
	  exec_file_command (execarg, !batch);
	  symbol_file_command (symarg, 0);
	}
    }
  else
    {
      if (execarg != NULL)
	if (!SET_TOP_LEVEL ())
	  exec_file_command (execarg, !batch);
      if (symarg != NULL)
	if (!SET_TOP_LEVEL ())
	  symbol_file_command (symarg, 0);
    }
  do_cleanups (ALL_CLEANUPS);

  /* After the symbol file has been read, print a newline to get us
     beyond the copyright line...  But errors should still set off
     the error message with a (single) blank line.  */
  if (!quiet)
    printf_filtered ("\n");
  error_pre_print = "\n";
  warning_pre_print = "\nwarning: ";

  if (corearg != NULL)
    if (!SET_TOP_LEVEL ())
      core_file_command (corearg, !batch);
    else if (isdigit (corearg[0]) && !SET_TOP_LEVEL ())
      attach_command (corearg, !batch);
  do_cleanups (ALL_CLEANUPS);

  if (ttyarg != NULL)
    if (!SET_TOP_LEVEL ())
      tty_command (ttyarg, !batch);
  do_cleanups (ALL_CLEANUPS);

#ifdef ADDITIONAL_OPTION_HANDLER
  ADDITIONAL_OPTION_HANDLER;
#endif

  /* Error messages should no longer be distinguished with extra output. */
  error_pre_print = 0;
  warning_pre_print = "warning: ";

  /* Read the .gdbinit file in the current directory, *if* it isn't
     the same as the $HOME/.gdbinit file (it should exist, also).  */
  
  if (!homedir
      || memcmp ((char *) &homebuf, (char *) &cwdbuf, sizeof (struct stat)))
    if (!inhibit_gdbinit && access (gdbinit, R_OK) == 0)
      {
	if (!SET_TOP_LEVEL ())
	  source_command (gdbinit, 0);
      }
  do_cleanups (ALL_CLEANUPS);

  for (i = 0; i < ncmd; i++)
    {
      if (!SET_TOP_LEVEL ())
	{
	  if (cmdarg[i][0] == '-' && cmdarg[i][1] == '\0')
	    read_command_file (stdin);
	  else
	    source_command (cmdarg[i], !batch);
	  do_cleanups (ALL_CLEANUPS);
	}
    }
  free ((PTR)cmdarg);

  /* Read in the old history after all the command files have been read. */
  init_history();

  if (batch)
    {
      /* We have hit the end of the batch file.  */
      exit (0);
    }

  /* Do any host- or target-specific hacks.  This is used for i960 targets
     to force the user to set a nindy target and spec its parameters.  */

#ifdef BEFORE_MAIN_LOOP_HOOK
  BEFORE_MAIN_LOOP_HOOK;
#endif

  /* The command loop.  */

  while (1)
    {
      if (!SET_TOP_LEVEL ())
	{
	  do_cleanups (ALL_CLEANUPS);		/* Do complete cleanup */
	  command_loop ();
          quit_command ((char *)0, instream == stdin);
	}
    }
  /* No exit -- exit is through quit_command.  */
}

void
execute_user_command (c, args)
     struct cmd_list_element *c;
     char *args;
{
  register struct command_line *cmdlines;
  struct cleanup *old_chain;
  
  if (args)
    error ("User-defined commands cannot take arguments.");

  cmdlines = c->user_commands;
  if (cmdlines == 0)
    /* Null command */
    return;

  /* Set the instream to 0, indicating execution of a
     user-defined function.  */
  old_chain = make_cleanup (source_cleanup, instream);
  instream = (FILE *) 0;
  while (cmdlines)
    {
      execute_command (cmdlines->line, 0);
      cmdlines = cmdlines->next;
    }
  do_cleanups (old_chain);
}

/* Execute the line P as a command.
   Pass FROM_TTY as second argument to the defining function.  */

void
execute_command (p, from_tty)
     char *p;
     int from_tty;
{
  register struct cmd_list_element *c;
  register enum language flang;
  static int warned = 0;

  free_all_values ();

  /* This can happen when command_line_input hits end of file.  */
  if (p == NULL)
      return;
  
  while (*p == ' ' || *p == '\t') p++;
  if (*p)
    {
      char *arg;
      
      c = lookup_cmd (&p, cmdlist, "", 0, 1);
      /* Pass null arg rather than an empty one.  */
      arg = *p ? p : 0;

      /* If this command has been hooked, run the hook first. */
      if (c->hook)
	execute_user_command (c->hook, (char *)0);

      if (c->class == class_user)
	execute_user_command (c, arg);
      else if (c->type == set_cmd || c->type == show_cmd)
	do_setshow_command (arg, from_tty & caution, c);
      else if (c->function.cfunc == NO_FUNCTION)
	error ("That is not a command, just a help topic.");
      else
	(*c->function.cfunc) (arg, from_tty & caution);
   }

  /* Tell the user if the language has changed (except first time).  */
  if (current_language != expected_language)
  {
    if (language_mode == language_mode_auto) {
      language_info (1);	/* Print what changed.  */
    }
    warned = 0;
  }

  /* Warn the user if the working language does not match the
     language of the current frame.  Only warn the user if we are
     actually running the program, i.e. there is a stack. */
  /* FIXME:  This should be cacheing the frame and only running when
     the frame changes.  */
  if (target_has_stack)
  {
    flang = get_frame_language ();
    if (!warned
        && flang != language_unknown
	&& flang != current_language->la_language)
    {
      printf_filtered ("%s\n", lang_frame_mismatch_warn);
      warned = 1;
    }
  }
}

/* ARGSUSED */
static void
command_loop_marker (foo)
     int foo;
{
}

/* Read commands from `instream' and execute them
   until end of file or error reading instream.  */
static void
command_loop ()
{
  struct cleanup *old_chain;
  char *command;
  int stdin_is_tty = ISATTY (stdin);

  while (!feof (instream))
    {
      if (window_hook && instream == stdin)
	(*window_hook) (instream, prompt);

      quit_flag = 0;
      if (instream == stdin && stdin_is_tty)
	reinitialize_more_filter ();
      old_chain = make_cleanup (command_loop_marker, 0);
      command = command_line_input (instream == stdin ? prompt : (char *) NULL,
				      instream == stdin);
      if (command == 0)
	return;
      execute_command (command, instream == stdin);
      /* Do any commands attached to breakpoint we stopped at.  */
      bpstat_do_actions (&stop_bpstat);
      do_cleanups (old_chain);
    }
}

/* Commands call this if they do not want to be repeated by null lines.  */

void
dont_repeat ()
{
  /* If we aren't reading from standard input, we are saving the last
     thing read from stdin in line and don't want to delete it.  Null lines
     won't repeat here in any case.  */
  if (instream == stdin)
    *line = 0;
}

/* Read a line from the stream "instream" without command line editing.

   It prints PRROMPT once at the start.
   Action is compatible with "readline", e.g. space for the result is 
   malloc'd and should be freed by the caller.

   A NULL return means end of file.  */
char *
gdb_readline (prrompt)
     char *prrompt;
{
  int c;
  char *result;
  int input_index = 0;
  int result_size = 80;

  if (prrompt)
    {
      /* Don't use a _filtered function here.  It causes the assumed
	 character position to be off, since the newline we read from
	 the user is not accounted for.  */
      fputs (prrompt, stdout);
      fflush (stdout);
    }
  
  result = (char *) xmalloc (result_size);

  while (1)
    {
      /* Read from stdin if we are executing a user defined command.
	 This is the right thing for prompt_for_continue, at least.  */
      c = fgetc (instream ? instream : stdin);

      if (c == EOF)
	{
	  free (result);
	  return NULL;
	}

      if (c == '\n')
	break;

      result[input_index++] = c;
      while (input_index >= result_size)
	{
	  result_size *= 2;
	  result = (char *) xrealloc (result, result_size);
	}
    }

  result[input_index++] = '\0';
  return result;
}

/* Variables which control command line editing and history
   substitution.  These variables are given default values at the end
   of this file.  */
static int command_editing_p;
static int history_expansion_p;
static int write_history_p;
static int history_size;
static char *history_filename;

/* readline uses the word breaks for two things:
   (1) In figuring out where to point the TEXT parameter to the
   rl_completion_entry_function.  Since we don't use TEXT for much,
   it doesn't matter a lot what the word breaks are for this purpose, but
   it does affect how much stuff M-? lists.
   (2) If one of the matches contains a word break character, readline
   will quote it.  That's why we switch between
   gdb_completer_word_break_characters and
   gdb_completer_command_word_break_characters.  I'm not sure when
   we need this behavior (perhaps for funky characters in C++ symbols?).  */

/* Variables which are necessary for fancy command line editing.  */
char *gdb_completer_word_break_characters =
  " \t\n!@#$%^&*()+=|~`}{[]\"';:?/>.<,-";

/* When completing on command names, we remove '-' from the list of
   word break characters, since we use it in command names.  If the
   readline library sees one in any of the current completion strings,
   it thinks that the string needs to be quoted and automatically supplies
   a leading quote. */
char *gdb_completer_command_word_break_characters =
  " \t\n!@#$%^&*()+=|~`}{[]\"';:?/>.<,";

/* Characters that can be used to quote completion strings.  Note that we
   can't include '"' because the gdb C parser treats such quoted sequences
   as strings. */
char *gdb_completer_quote_characters =
  "'";

/* Functions that are used as part of the fancy command line editing.  */

/* This can be used for functions which don't want to complete on symbols
   but don't want to complete on anything else either.  */
/* ARGSUSED */
char **
noop_completer (text, prefix)
     char *text;
     char *prefix;
{
  return NULL;
}

/* Complete on filenames.  */
char **
filename_completer (text, word)
     char *text;
     char *word;
{
  /* From readline.  */
  extern char *filename_completion_function ();
  int subsequent_name;
  char **return_val;
  int return_val_used;
  int return_val_alloced;

  return_val_used = 0;
  /* Small for testing.  */
  return_val_alloced = 1;
  return_val = (char **) xmalloc (return_val_alloced * sizeof (char *));

  subsequent_name = 0;
  while (1)
    {
      char *p;
      p = filename_completion_function (text, subsequent_name);
      if (return_val_used >= return_val_alloced)
	{
	  return_val_alloced *= 2;
	  return_val =
	    (char **) xrealloc (return_val,
				return_val_alloced * sizeof (char *));
	}
      if (p == NULL)
	{
	  return_val[return_val_used++] = p;
	  break;
	}
      /* Like emacs, don't complete on old versions.  Especially useful
	 in the "source" command.  */
      if (p[strlen (p) - 1] == '~')
	continue;

      {
	char *q;
	if (word == text)
	  /* Return exactly p.  */
	  return_val[return_val_used++] = p;
	else if (word > text)
	  {
	    /* Return some portion of p.  */
	    q = xmalloc (strlen (p) + 5);
	    strcpy (q, p + (word - text));
	    return_val[return_val_used++] = q;
	    free (p);
	  }
	else
	  {
	    /* Return some of TEXT plus p.  */
	    q = xmalloc (strlen (p) + (text - word) + 5);
	    strncpy (q, word, text - word);
	    q[text - word] = '\0';
	    strcat (q, p);
	    return_val[return_val_used++] = q;
	    free (p);
	  }
      }
      subsequent_name = 1;
    }
#if 0
  /* There is no way to do this just long enough to affect quote inserting
     without also affecting the next completion.  This should be fixed in
     readline.  FIXME.  */
  /* Insure that readline does the right thing
     with respect to inserting quotes.  */
  rl_completer_word_break_characters = "";
#endif
  return return_val;
}

/* Here are some useful test cases for completion.  FIXME: These should
   be put in the test suite.  They should be tested with both M-? and TAB.

   "show output-" "radix"
   "show output" "-radix"
   "p" ambiguous (commands starting with p--path, print, printf, etc.)
   "p "  ambiguous (all symbols)
   "info t foo" no completions
   "info t " no completions
   "info t" ambiguous ("info target", "info terminal", etc.)
   "info ajksdlfk" no completions
   "info ajksdlfk " no completions
   "info" " "
   "info " ambiguous (all info commands)
   "p \"a" no completions (string constant)
   "p 'a" ambiguous (all symbols starting with a)
   "p b-a" ambiguous (all symbols starting with a)
   "p b-" ambiguous (all symbols)
   "file Make" "file" (word break hard to screw up here)
   "file ../gdb.stabs/wi" "erd" (needs to not break word at slash)
   */

/* Generate completions one by one for the completer.  Each time we are
   called return another potential completion to the caller.  The function
   is misnamed; it just completes on commands or passes the buck to the
   command's completer function; the stuff specific to symbol completion
   is in make_symbol_completion_list.

   TEXT is readline's idea of the "word" we are looking at; we don't really
   like readline's ideas about word breaking so we ignore it.

   MATCHES is the number of matches that have currently been collected from
   calling this completion function.  When zero, then we need to initialize,
   otherwise the initialization has already taken place and we can just
   return the next potential completion string.

   Returns NULL if there are no more completions, else a pointer to a string
   which is a possible completion.

   RL_LINE_BUFFER is available to be looked at; it contains the entire text
   of the line.  RL_POINT is the offset in that line of the cursor.  You
   should pretend that the line ends at RL_POINT. */

static char *
symbol_completion_function (text, matches)
     char *text;
     int matches;
{
  static char **list = (char **)NULL;		/* Cache of completions */
  static int index;				/* Next cached completion */
  char *output = NULL;
  char *tmp_command, *p;
  /* Pointer within tmp_command which corresponds to text.  */
  char *word;
  struct cmd_list_element *c, *result_list;
  extern char *rl_line_buffer;
  extern int rl_point;

  if (matches == 0)
    {
      /* The caller is beginning to accumulate a new set of completions, so
	 we need to find all of them now, and cache them for returning one at
	 a time on future calls. */

      if (list)
	{
	  /* Free the storage used by LIST, but not by the strings inside.
	     This is because rl_complete_internal () frees the strings. */
	  free ((PTR)list);
	}
      list = 0;
      index = 0;

      /* Choose the default set of word break characters to break completions.
	 If we later find out that we are doing completions on command strings
	 (as opposed to strings supplied by the individual command completer
	 functions, which can be any string) then we will switch to the
	 special word break set for command strings, which leaves out the
	 '-' character used in some commands.  */

      rl_completer_word_break_characters =
	  gdb_completer_word_break_characters;

      /* Decide whether to complete on a list of gdb commands or on symbols. */
      tmp_command = (char *) alloca (rl_point + 1);
      p = tmp_command;

      strncpy (tmp_command, rl_line_buffer, rl_point);
      tmp_command[rl_point] = '\0';
      /* Since text always contains some number of characters leading up
	 to rl_point, we can find the equivalent position in tmp_command
	 by subtracting that many characters from the end of tmp_command.  */
      word = tmp_command + rl_point - strlen (text);

      if (rl_point == 0)
	{
	  /* An empty line we want to consider ambiguous; that is, it
	     could be any command.  */
	  c = (struct cmd_list_element *) -1;
	  result_list = 0;
	}
      else
	{
	  c = lookup_cmd_1 (&p, cmdlist, &result_list, 1);
	}

      /* Move p up to the next interesting thing.  */
      while (*p == ' ' || *p == '\t')
	{
	  p++;
	}

      if (!c)
	{
	  /* It is an unrecognized command.  So there are no
	     possible completions.  */
	  list = NULL;
	}
      else if (c == (struct cmd_list_element *) -1)
	{
	  char *q;

	  /* lookup_cmd_1 advances p up to the first ambiguous thing, but
	     doesn't advance over that thing itself.  Do so now.  */
	  q = p;
	  while (*q && (isalnum (*q) || *q == '-' || *q == '_'))
	    ++q;
	  if (q != tmp_command + rl_point)
	    {
	      /* There is something beyond the ambiguous
		 command, so there are no possible completions.  For
		 example, "info t " or "info t foo" does not complete
		 to anything, because "info t" can be "info target" or
		 "info terminal".  */
	      list = NULL;
	    }
	  else
	    {
	      /* We're trying to complete on the command which was ambiguous.
		 This we can deal with.  */
	      if (result_list)
		{
		  list = complete_on_cmdlist (*result_list->prefixlist, p,
					      word);
		}
	      else
		{
		  list = complete_on_cmdlist (cmdlist, p, word);
		}
	      /* Insure that readline does the right thing with respect to
		 inserting quotes.  */
	      rl_completer_word_break_characters =
		gdb_completer_command_word_break_characters;
	    }
	}
      else
	{
	  /* We've recognized a full command.  */

	  if (p == tmp_command + rl_point)
	    {
	      /* There is no non-whitespace in the line beyond the command.  */

	      if (p[-1] == ' ' || p[-1] == '\t')
		{
		  /* The command is followed by whitespace; we need to complete
		     on whatever comes after command.  */
		  if (c->prefixlist)
		    {
		      /* It is a prefix command; what comes after it is
			 a subcommand (e.g. "info ").  */
		      list = complete_on_cmdlist (*c->prefixlist, p, word);

		      /* Insure that readline does the right thing
			 with respect to inserting quotes.  */
		      rl_completer_word_break_characters =
			gdb_completer_command_word_break_characters;
		    }
		  else
		    {
		      /* It is a normal command; what comes after it is
			 completed by the command's completer function.  */
		      list = (*c->completer) (p, word);
		    }
		}
	      else
		{
		  /* The command is not followed by whitespace; we need to
		     complete on the command itself.  e.g. "p" which is a
		     command itself but also can complete to "print", "ptype"
		     etc.  */
		  char *q;

		  /* Find the command we are completing on.  */
		  q = p;
		  while (q > tmp_command)
		    {
		      if (isalnum (q[-1]) || q[-1] == '-' || q[-1] == '_')
			--q;
		      else
			break;
		    }

		  list = complete_on_cmdlist (result_list, q, word);

		  /* Insure that readline does the right thing
		     with respect to inserting quotes.  */
		  rl_completer_word_break_characters =
		    gdb_completer_command_word_break_characters;
		}
	    }
	  else
	    {
	      /* There is non-whitespace beyond the command.  */

	      if (c->prefixlist && !c->allow_unknown)
		{
		  /* It is an unrecognized subcommand of a prefix command,
		     e.g. "info adsfkdj".  */
		  list = NULL;
		}
	      else
		{
		  /* It is a normal command.  */
		  list = (*c->completer) (p, word);
		}
	    }
	}
    }

  /* If we found a list of potential completions during initialization then
     dole them out one at a time.  The vector of completions is NULL
     terminated, so after returning the last one, return NULL (and continue
     to do so) each time we are called after that, until a new list is
     available. */

  if (list)
    {
      output = list[index];
      if (output)
	{
	  index++;
	}
    }

#if 0
  /* Can't do this because readline hasn't yet checked the word breaks
     for figuring out whether to insert a quote.  */
  if (output == NULL)
    /* Make sure the word break characters are set back to normal for the
       next time that readline tries to complete something.  */
    rl_completer_word_break_characters =
      gdb_completer_word_break_characters;
#endif

  return (output);
}

/* Skip over a possibly quoted word (as defined by the quote characters
   and word break characters the completer uses).  Returns pointer to the
   location after the "word". */

char *
skip_quoted (str)
     char *str;
{
  char quote_char = '\0';
  char *scan;

  for (scan = str; *scan != '\0'; scan++)
    {
      if (quote_char != '\0')
	{
	  /* Ignore everything until the matching close quote char */
	  if (*scan == quote_char)
	    {
	      /* Found matching close quote. */
	      scan++;
	      break;
	    }
	}
      else if (strchr (gdb_completer_quote_characters, *scan))
	{
	  /* Found start of a quoted string. */
	  quote_char = *scan;
	}
      else if (strchr (gdb_completer_word_break_characters, *scan))
	{
	  break;
	}
    }
  return (scan);
}


#ifdef STOP_SIGNAL
static void
stop_sig (signo)
int signo;
{
#if STOP_SIGNAL == SIGTSTP
  signal (SIGTSTP, SIG_DFL);
  sigsetmask (0);
  kill (getpid (), SIGTSTP);
  signal (SIGTSTP, stop_sig);
#else
  signal (STOP_SIGNAL, stop_sig);
#endif
  printf ("%s", prompt);
  fflush (stdout);

  /* Forget about any previous command -- null line now will do nothing.  */
  dont_repeat ();
}
#endif /* STOP_SIGNAL */

/* Initialize signal handlers. */
static void
do_nothing (signo)
int signo;
{
}

static void
init_signals ()
{
  signal (SIGINT, request_quit);

  /* If we initialize SIGQUIT to SIG_IGN, then the SIG_IGN will get
     passed to the inferior, which we don't want.  It would be
     possible to do a "signal (SIGQUIT, SIG_DFL)" after we fork, but
     on BSD4.3 systems using vfork, that can affect the
     GDB process as well as the inferior (the signal handling tables
     might be in memory, shared between the two).  Since we establish
     a handler for SIGQUIT, when we call exec it will set the signal
     to SIG_DFL for us.  */
  signal (SIGQUIT, do_nothing);
  if (signal (SIGHUP, do_nothing) != SIG_IGN)
    signal (SIGHUP, disconnect);
  signal (SIGFPE, float_handler);

#if defined(SIGWINCH) && defined(SIGWINCH_HANDLER)
  signal (SIGWINCH, SIGWINCH_HANDLER);
#endif
}

/* Read one line from the command input stream `instream'
   into the local static buffer `linebuffer' (whose current length
   is `linelength').
   The buffer is made bigger as necessary.
   Returns the address of the start of the line.

   NULL is returned for end of file.

   *If* the instream == stdin & stdin is a terminal, the line read
   is copied into the file line saver (global var char *line,
   length linesize) so that it can be duplicated.

   This routine either uses fancy command line editing or
   simple input as the user has requested.  */

char *
command_line_input (prrompt, repeat)
     char *prrompt;
     int repeat;
{
  static char *linebuffer = 0;
  static unsigned linelength = 0;
  register char *p;
  char *p1;
  char *rl;
  char *local_prompt = prrompt;
  register int c;
  char *nline;
  char got_eof = 0;

  if (linebuffer == 0)
    {
      linelength = 80;
      linebuffer = (char *) xmalloc (linelength);
    }

  p = linebuffer;

  /* Control-C quits instantly if typed while in this loop
     since it should not wait until the user types a newline.  */
  immediate_quit++;
#ifdef STOP_SIGNAL
  if (job_control)
    signal (STOP_SIGNAL, stop_sig);
#endif

  while (1)
    {
      /* Reports are that some Sys V's don't flush stdout/err on reads
	 from stdin, when stdin/out are sockets rather than ttys.  So we
	 have to do it ourselves, to make emacs-gdb and xxgdb work.
	 On other machines, doing this once per input should be a cheap nop.  */
      fflush (stdout);
      fflush (stderr);

      /* Don't use fancy stuff if not talking to stdin.  */
      if (command_editing_p && instream == stdin
	  && ISATTY (instream))
	rl = readline (local_prompt);
      else
	rl = gdb_readline (local_prompt);

      if (!rl || rl == (char *) EOF)
	{
	  got_eof = 1;
	  break;
	}
      if (strlen(rl) + 1 + (p - linebuffer) > linelength)
	{
	  linelength = strlen(rl) + 1 + (p - linebuffer);
	  nline = (char *) xrealloc (linebuffer, linelength);
	  p += nline - linebuffer;
	  linebuffer = nline;
	}
      p1 = rl;
      /* Copy line.  Don't copy null at end.  (Leaves line alone
         if this was just a newline)  */
      while (*p1)
	*p++ = *p1++;

      free (rl);			/* Allocated in readline.  */

      if (p == linebuffer || *(p - 1) != '\\')
	break;

      p--;			/* Put on top of '\'.  */
      local_prompt = (char *) 0;
  }

#ifdef STOP_SIGNAL
  if (job_control)
    signal (STOP_SIGNAL, SIG_DFL);
#endif
  immediate_quit--;

  if (got_eof)
    return NULL;

  /* Do history expansion if that is wished.  */
  if (history_expansion_p && instream == stdin
      && ISATTY (instream))
    {
      char *history_value;
      int expanded;

      *p = '\0';		/* Insert null now.  */
      expanded = history_expand (linebuffer, &history_value);
      if (expanded)
	{
	  /* Print the changes.  */
	  printf ("%s\n", history_value);

	  /* If there was an error, call this function again.  */
	  if (expanded < 0)
	    {
	      free (history_value);
	      return command_line_input (prrompt, repeat);
	    }
	  if (strlen (history_value) > linelength)
	    {
	      linelength = strlen (history_value) + 1;
	      linebuffer = (char *) xrealloc (linebuffer, linelength);
	    }
	  strcpy (linebuffer, history_value);
	  p = linebuffer + strlen(linebuffer);
	  free (history_value);
	}
    }

  /* If we just got an empty line, and that is supposed
     to repeat the previous command, return the value in the
     global buffer.  */
  if (repeat)
    {
      if (p == linebuffer)
	return line;
      p1 = linebuffer;
      while (*p1 == ' ' || *p1 == '\t')
	p1++;
      if (!*p1)
	return line;
    }

  *p = 0;

  /* Add line to history if appropriate.  */
  if (instream == stdin
      && ISATTY (stdin) && *linebuffer)
    add_history (linebuffer);

  /* Note: lines consisting soley of comments are added to the command
     history.  This is useful when you type a command, and then
     realize you don't want to execute it quite yet.  You can comment
     out the command and then later fetch it from the value history
     and remove the '#'.  The kill ring is probably better, but some
     people are in the habit of commenting things out.  */
  p1 = linebuffer;
  while ((c = *p1++) != '\0')
    {
      if (c == '"')
	while ((c = *p1++) != '"')
	  {
	    /* Make sure an escaped '"' doesn't make us think the string
	       is ended.  */
	    if (c == '\\')
	      parse_escape (&p1);
	    if (c == '\0')
	      break;
	  }
      else if (c == '\'')
	while ((c = *p1++) != '\'')
	  {
	    /* Make sure an escaped '\'' doesn't make us think the string
	       is ended.  */
	    if (c == '\\')
	      parse_escape (&p1);
	    if (c == '\0')
	      break;
	  }
      else if (c == '#')
	{
	  /* Found a comment.  */
	  p1[-1] = '\0';
	  break;
	}
    }

  /* Save into global buffer if appropriate.  */
  if (repeat)
    {
      if (linelength > linesize)
	{
	  line = xrealloc (line, linelength);
	  linesize = linelength;
	}
      strcpy (line, linebuffer);
      return line;
    }

  return linebuffer;
}

/* Read lines from the input stream
   and accumulate them in a chain of struct command_line's
   which is then returned.  */

struct command_line *
read_command_lines ()
{
  struct command_line *first = 0;
  register struct command_line *next, *tail = 0;
  register char *p, *p1;
  struct cleanup *old_chain = 0;

  while (1)
    {
      dont_repeat ();
      p = command_line_input ((char *) NULL, instream == stdin);
      if (p == NULL)
	/* Treat end of file like "end".  */
	break;
      
      /* Remove leading and trailing blanks.  */
      while (*p == ' ' || *p == '\t') p++;
      p1 = p + strlen (p);
      while (p1 != p && (p1[-1] == ' ' || p1[-1] == '\t')) p1--;

      /* Is this "end"?  */
      if (p1 - p == 3 && !strncmp (p, "end", 3))
	break;

      /* No => add this line to the chain of command lines.  */
      next = (struct command_line *) xmalloc (sizeof (struct command_line));
      next->line = savestring (p, p1 - p);
      next->next = 0;
      if (tail)
	{
	  tail->next = next;
	}
      else
	{
	  /* We just read the first line.
	     From now on, arrange to throw away the lines we have
	     if we quit or get an error while inside this function.  */
	  first = next;
	  old_chain = make_cleanup (free_command_lines, &first);
	}
      tail = next;
    }

  dont_repeat ();

  /* Now we are about to return the chain to our caller,
     so freeing it becomes his responsibility.  */
  if (first)
    discard_cleanups (old_chain);
  return first;
}

/* Free a chain of struct command_line's.  */

void
free_command_lines (lptr)
      struct command_line **lptr;
{
  register struct command_line *l = *lptr;
  register struct command_line *next;

  while (l)
    {
      next = l->next;
      free (l->line);
      free ((PTR)l);
      l = next;
    }
}

/* Add an element to the list of info subcommands.  */

void
add_info (name, fun, doc)
     char *name;
     void (*fun) PARAMS ((char *, int));
     char *doc;
{
  add_cmd (name, no_class, fun, doc, &infolist);
}

/* Add an alias to the list of info subcommands.  */

void
add_info_alias (name, oldname, abbrev_flag)
     char *name;
     char *oldname;
     int abbrev_flag;
{
  add_alias_cmd (name, oldname, 0, abbrev_flag, &infolist);
}

/* The "info" command is defined as a prefix, with allow_unknown = 0.
   Therefore, its own definition is called only for "info" with no args.  */

/* ARGSUSED */
static void
info_command (arg, from_tty)
     char *arg;
     int from_tty;
{
  printf ("\"info\" must be followed by the name of an info command.\n");
  help_list (infolist, "info ", -1, stdout);
}

/* The "show" command with no arguments shows all the settings.  */

/* ARGSUSED */
static void
show_command (arg, from_tty)
     char *arg;
     int from_tty;
{
  cmd_show_list (showlist, from_tty, "");
}

/* Add an element to the list of commands.  */

void
add_com (name, class, fun, doc)
     char *name;
     enum command_class class;
     void (*fun) PARAMS ((char *, int));
     char *doc;
{
  add_cmd (name, class, fun, doc, &cmdlist);
}

/* Add an alias or abbreviation command to the list of commands.  */

void
add_com_alias (name, oldname, class, abbrev_flag)
     char *name;
     char *oldname;
     enum command_class class;
     int abbrev_flag;
{
  add_alias_cmd (name, oldname, class, abbrev_flag, &cmdlist);
}

void
error_no_arg (why)
     char *why;
{
  error ("Argument required (%s).", why);
}

/* ARGSUSED */
static void
help_command (command, from_tty)
     char *command;
     int from_tty; /* Ignored */
{
  help_cmd (command, stdout);
}

static void
validate_comname (comname)
     char *comname;
{
  register char *p;

  if (comname == 0)
    error_no_arg ("name of command to define");

  p = comname;
  while (*p)
    {
      if (!isalnum(*p) && *p != '-')
	error ("Junk in argument list: \"%s\"", p);
      p++;
    }
}

/* This is just a placeholder in the command data structures.  */
static void
user_defined_command (ignore, from_tty)
     char *ignore;
     int from_tty;
{
}

static void
define_command (comname, from_tty)
     char *comname;
     int from_tty;
{
  register struct command_line *cmds;
  register struct cmd_list_element *c, *newc, *hookc = 0;
  char *tem = comname;
#define	HOOK_STRING	"hook-"
#define	HOOK_LEN 5

  validate_comname (comname);

  /* Look it up, and verify that we got an exact match.  */
  c = lookup_cmd (&tem, cmdlist, "", -1, 1);
  if (c && !STREQ (comname, c->name))
    c = 0;
    
  if (c)
    {
      if (c->class == class_user || c->class == class_alias)
	tem = "Redefine command \"%s\"? ";
      else
	tem = "Really redefine built-in command \"%s\"? ";
      if (!query (tem, c->name))
	error ("Command \"%s\" not redefined.", c->name);
    }

  /* If this new command is a hook, then mark the command which it
     is hooking.  Note that we allow hooking `help' commands, so that
     we can hook the `stop' pseudo-command.  */

  if (!strncmp (comname, HOOK_STRING, HOOK_LEN))
    {
      /* Look up cmd it hooks, and verify that we got an exact match.  */
      tem = comname+HOOK_LEN;
      hookc = lookup_cmd (&tem, cmdlist, "", -1, 0);
      if (hookc && !STREQ (comname+HOOK_LEN, hookc->name))
	hookc = 0;
      if (!hookc)
	{
	  warning ("Your new `%s' command does not hook any existing command.",
		   comname);
	  if (!query ("Proceed? ", (char *)0))
	    error ("Not confirmed.");
	}
    }

  comname = savestring (comname, strlen (comname));

  /* If the rest of the commands will be case insensitive, this one 
     should behave in the same manner. */
  for (tem = comname; *tem; tem++)
    if (isupper(*tem)) *tem = tolower(*tem);

  if (from_tty)
    {
      printf ("Type commands for definition of \"%s\".\n\
End with a line saying just \"end\".\n", comname);
      fflush (stdout);
    }

  cmds = read_command_lines ();

  if (c && c->class == class_user)
    free_command_lines (&c->user_commands);

  newc = add_cmd (comname, class_user, user_defined_command,
	   (c && c->class == class_user)
	   ? c->doc : savestring ("User-defined.", 13), &cmdlist);
  newc->user_commands = cmds;

  /* If this new command is a hook, then mark both commands as being
     tied.  */
  if (hookc)
    {
      hookc->hook = newc;	/* Target gets hooked.  */
      newc->hookee = hookc;	/* We are marked as hooking target cmd.  */
    }
}

static void
document_command (comname, from_tty)
     char *comname;
     int from_tty;
{
  struct command_line *doclines;
  register struct cmd_list_element *c;
  char *tem = comname;

  validate_comname (comname);

  c = lookup_cmd (&tem, cmdlist, "", 0, 1);

  if (c->class != class_user)
    error ("Command \"%s\" is built-in.", comname);

  if (from_tty)
    printf ("Type documentation for \"%s\".\n\
End with a line saying just \"end\".\n", comname);

  doclines = read_command_lines ();

  if (c->doc) free (c->doc);

  {
    register struct command_line *cl1;
    register int len = 0;

    for (cl1 = doclines; cl1; cl1 = cl1->next)
      len += strlen (cl1->line) + 1;

    c->doc = (char *) xmalloc (len + 1);
    *c->doc = 0;

    for (cl1 = doclines; cl1; cl1 = cl1->next)
      {
	strcat (c->doc, cl1->line);
	if (cl1->next)
	  strcat (c->doc, "\n");
      }
  }

  free_command_lines (&doclines);
}

static void
print_gnu_advertisement()
{
    printf ("\
GDB is free software and you are welcome to distribute copies of it\n\
 under certain conditions; type \"show copying\" to see the conditions.\n\
There is absolutely no warranty for GDB; type \"show warranty\" for details.\n\
");
}

static void
print_gdb_version (stream)
  FILE *stream;
{
  fprintf_filtered (stream, "\
GDB %s (%s", version, host_canonical);

  if (strcmp(host_canonical, target_canonical))
    fprintf_filtered (stream, " --target %s", target_canonical);

  fprintf_filtered (stream, "), ");
  wrap_here("");
  fprintf_filtered (stream, "Copyright 1993 Free Software Foundation, Inc.");
}

/* ARGSUSED */
static void
show_version (args, from_tty)
     char *args;
     int from_tty;
{
  immediate_quit++;
  print_gnu_advertisement ();
  print_gdb_version (stdout);
  printf_filtered ("\n");
  immediate_quit--;
}

/* xgdb calls this to reprint the usual GDB prompt.  */

void
print_prompt ()
{
  printf ("%s", prompt);
  fflush (stdout);
}

static void
quit_command (args, from_tty)
     char *args;
     int from_tty;
{
  if (inferior_pid != 0 && target_has_execution)
    {
      if (attach_flag)
	{
	  if (query ("The program is running.  Quit anyway (and detach it)? "))
	    target_detach (args, from_tty);
	  else
	    error ("Not confirmed.");
	}
      else
	{
	  if (query ("The program is running.  Quit anyway (and kill it)? "))
	    target_kill ();
	  else
	    error ("Not confirmed.");
	}
    }
  /* Save the history information if it is appropriate to do so.  */
  if (write_history_p && history_filename)
    write_history (history_filename);
  exit (0);
}

/* Returns whether GDB is running on a terminal and whether the user
   desires that questions be asked of them on that terminal.  */

int
input_from_terminal_p ()
{
  return gdb_has_a_terminal () && (instream == stdin) & caution;
}

/* ARGSUSED */
static void
pwd_command (args, from_tty)
     char *args;
     int from_tty;
{
  if (args) error ("The \"pwd\" command does not take an argument: %s", args);
  getcwd (dirbuf, sizeof (dirbuf));

  if (!STREQ (dirbuf, current_directory))
    printf ("Working directory %s\n (canonically %s).\n",
	    current_directory, dirbuf);
  else
    printf ("Working directory %s.\n", current_directory);
}

static void
cd_command (dir, from_tty)
     char *dir;
     int from_tty;
{
  int len;
  /* Found something other than leading repetitions of "/..".  */
  int found_real_path;
  char *p;

  /* If the new directory is absolute, repeat is a no-op; if relative,
     repeat might be useful but is more likely to be a mistake.  */
  dont_repeat ();

  if (dir == 0)
    error_no_arg ("new working directory");

  dir = tilde_expand (dir);
  make_cleanup (free, dir);

  if (chdir (dir) < 0)
    perror_with_name (dir);

  len = strlen (dir);
  dir = savestring (dir, len - (len > 1 && dir[len-1] == '/'));
  if (dir[0] == '/')
    current_directory = dir;
  else
    {
      if (current_directory[0] == '/' && current_directory[1] == '\0')
	current_directory = concat (current_directory, dir, NULL);
      else
	current_directory = concat (current_directory, "/", dir, NULL);
      free (dir);
    }

  /* Now simplify any occurrences of `.' and `..' in the pathname.  */

  found_real_path = 0;
  for (p = current_directory; *p;)
    {
      if (p[0] == '/' && p[1] == '.' && (p[2] == 0 || p[2] == '/'))
	strcpy (p, p + 2);
      else if (p[0] == '/' && p[1] == '.' && p[2] == '.'
	       && (p[3] == 0 || p[3] == '/'))
	{
	  if (found_real_path)
	    {
	      /* Search backwards for the directory just before the "/.."
		 and obliterate it and the "/..".  */
	      char *q = p;
	      while (q != current_directory && q[-1] != '/')
		--q;

	      if (q == current_directory)
		/* current_directory is
		   a relative pathname ("can't happen"--leave it alone).  */
		++p;
	      else
		{
		  strcpy (q - 1, p + 3);
		  p = q - 1;
		}
	    }
	  else
	    /* We are dealing with leading repetitions of "/..", for example
	       "/../..", which is the Mach super-root.  */
	    p += 3;
	}
      else
	{
	  found_real_path = 1;
	  ++p;
	}
    }

  forget_cached_source_info ();

  if (from_tty)
    pwd_command ((char *) 0, 1);
}

/* ARGSUSED */
static void
source_command (args, from_tty)
     char *args;
     int from_tty;
{
  FILE *stream;
  struct cleanup *cleanups;
  char *file = args;

  if (file == NULL)
    {
      error ("source command requires pathname of file to source.");
    }

  file = tilde_expand (file);
  make_cleanup (free, file);

  stream = fopen (file, FOPEN_RT);
  if (stream == 0)
    perror_with_name (file);

  cleanups = make_cleanup (fclose, stream);

  read_command_file (stream);

  do_cleanups (cleanups);
}

/* ARGSUSED */
static void
echo_command (text, from_tty)
     char *text;
     int from_tty;
{
  char *p = text;
  register int c;

  if (text)
    while ((c = *p++) != '\0')
      {
	if (c == '\\')
	  {
	    /* \ at end of argument is used after spaces
	       so they won't be lost.  */
	    if (*p == 0)
	      return;

	    c = parse_escape (&p);
	    if (c >= 0)
	      printf_filtered ("%c", c);
	  }
	else
	  printf_filtered ("%c", c);
      }

  /* Force this output to appear now.  */
  wrap_here ("");
  fflush (stdout);
}


/* Functions to manipulate command line editing control variables.  */

/* Number of commands to print in each call to show_commands.  */
#define Hist_print 10
static void
show_commands (args, from_tty)
     char *args;
     int from_tty;
{
  /* Index for history commands.  Relative to history_base.  */
  int offset;

  /* Number of the history entry which we are planning to display next.
     Relative to history_base.  */
  static int num = 0;

  /* The first command in the history which doesn't exist (i.e. one more
     than the number of the last command).  Relative to history_base.  */
  int hist_len;

  extern struct _hist_entry *history_get PARAMS ((int));
  extern int history_base;

  /* Print out some of the commands from the command history.  */
  /* First determine the length of the history list.  */
  hist_len = history_size;
  for (offset = 0; offset < history_size; offset++)
    {
      if (!history_get (history_base + offset))
	{
	  hist_len = offset;
	  break;
	}
    }

  if (args)
    {
      if (args[0] == '+' && args[1] == '\0')
	/* "info editing +" should print from the stored position.  */
	;
      else
	/* "info editing <exp>" should print around command number <exp>.  */
	num = (parse_and_eval_address (args) - history_base) - Hist_print / 2;
    }
  /* "show commands" means print the last Hist_print commands.  */
  else
    {
      num = hist_len - Hist_print;
    }

  if (num < 0)
    num = 0;

  /* If there are at least Hist_print commands, we want to display the last
     Hist_print rather than, say, the last 6.  */
  if (hist_len - num < Hist_print)
    {
      num = hist_len - Hist_print;
      if (num < 0)
	num = 0;
    }

  for (offset = num; offset < num + Hist_print && offset < hist_len; offset++)
    {
      printf_filtered ("%5d  %s\n", history_base + offset,
	      (history_get (history_base + offset))->line);
    }

  /* The next command we want to display is the next one that we haven't
     displayed yet.  */
  num += Hist_print;
  
  /* If the user repeats this command with return, it should do what
     "show commands +" does.  This is unnecessary if arg is null,
     because "show commands +" is not useful after "show commands".  */
  if (from_tty && args)
    {
      args[0] = '+';
      args[1] = '\0';
    }
}

/* Called by do_setshow_command.  */
/* ARGSUSED */
static void
set_history_size_command (args, from_tty, c)
     char *args;
     int from_tty;
     struct cmd_list_element *c;
{
  if (history_size == INT_MAX)
    unstifle_history ();
  else if (history_size >= 0)
    stifle_history (history_size);
  else
    {
      history_size = INT_MAX;
      error ("History size must be non-negative");
    }
}

/* ARGSUSED */
static void
set_history (args, from_tty)
     char *args;
     int from_tty;
{
  printf ("\"set history\" must be followed by the name of a history subcommand.\n");
  help_list (sethistlist, "set history ", -1, stdout);
}

/* ARGSUSED */
static void
show_history (args, from_tty)
     char *args;
     int from_tty;
{
  cmd_show_list (showhistlist, from_tty, "");
}

int info_verbose = 0;		/* Default verbose msgs off */

/* Called by do_setshow_command.  An elaborate joke.  */
/* ARGSUSED */
static void 
set_verbose (args, from_tty, c)
     char *args;
     int from_tty;
     struct cmd_list_element *c;
{
  char *cmdname = "verbose";
  struct cmd_list_element *showcmd;
  
  showcmd = lookup_cmd_1 (&cmdname, showlist, NULL, 1);

  if (info_verbose)
    {
      c->doc = "Set verbose printing of informational messages.";
      showcmd->doc = "Show verbose printing of informational messages.";
    }
  else
    {
      c->doc = "Set verbosity.";
      showcmd->doc = "Show verbosity.";
    }
}

static void
float_handler (signo)
int signo;
{
  /* This message is based on ANSI C, section 4.7.  Note that integer
     divide by zero causes this, so "float" is a misnomer.  */
  signal (SIGFPE, float_handler);
  error ("Erroneous arithmetic operation.");
}

/* Return whether we are running a batch file or from terminal.  */
int
batch_mode ()
{
  return !(instream == stdin && ISATTY (stdin));
}


static void
init_cmd_lists ()
{
  cmdlist = NULL;
  infolist = NULL;
  enablelist = NULL;
  disablelist = NULL;
  deletelist = NULL;
  enablebreaklist = NULL;
  setlist = NULL;
  unsetlist = NULL;
  showlist = NULL;
  sethistlist = NULL;
  showhistlist = NULL;
  unsethistlist = NULL;
#if MAINTENANCE_CMDS
  maintenancelist = NULL;
  maintenanceinfolist = NULL;
  maintenanceprintlist = NULL;
#endif
  setprintlist = NULL;
  showprintlist = NULL;
  setchecklist = NULL;
  showchecklist = NULL;
}

/* Init the history buffer.  Note that we are called after the init file(s)
 * have been read so that the user can change the history file via his
 * .gdbinit file (for instance).  The GDBHISTFILE environment variable
 * overrides all of this.
 */

static void
init_history()
{
  char *tmpenv;

  tmpenv = getenv ("HISTSIZE");
  if (tmpenv)
    history_size = atoi (tmpenv);
  else if (!history_size)
    history_size = 256;

  stifle_history (history_size);

  tmpenv = getenv ("GDBHISTFILE");
  if (tmpenv)
    history_filename = savestring (tmpenv, strlen(tmpenv));
  else if (!history_filename) {
    /* We include the current directory so that if the user changes
       directories the file written will be the same as the one
       that was read.  */
    history_filename = concat (current_directory, "/.gdb_history", NULL);
  }
  read_history (history_filename);
}

static void
init_main ()
{
  struct cmd_list_element *c;
  
#ifdef DEFAULT_PROMPT
  prompt = savestring (DEFAULT_PROMPT, strlen(DEFAULT_PROMPT));
#else
  prompt = savestring ("(gdb) ", 6);
#endif

  /* Set the important stuff up for command editing.  */
  command_editing_p = 1;
  history_expansion_p = 0;
  write_history_p = 0;
  
  /* Setup important stuff for command line editing.  */
  rl_completion_entry_function = (int (*)()) symbol_completion_function;
  rl_completer_word_break_characters = gdb_completer_word_break_characters;
  rl_completer_quote_characters = gdb_completer_quote_characters;
  rl_readline_name = "gdb";

  /* Define the classes of commands.
     They will appear in the help list in the reverse of this order.  */

  add_cmd ("internals", class_maintenance, NO_FUNCTION,
	   "Maintenance commands.\n\
Some gdb commands are provided just for use by gdb maintainers.\n\
These commands are subject to frequent change, and may not be as\n\
well documented as user commands.",
	   &cmdlist);
  add_cmd ("obscure", class_obscure, NO_FUNCTION, "Obscure features.", &cmdlist);
  add_cmd ("aliases", class_alias, NO_FUNCTION, "Aliases of other commands.", &cmdlist);
  add_cmd ("user-defined", class_user, NO_FUNCTION, "User-defined commands.\n\
The commands in this class are those defined by the user.\n\
Use the \"define\" command to define a command.", &cmdlist);
  add_cmd ("support", class_support, NO_FUNCTION, "Support facilities.", &cmdlist);
  add_cmd ("status", class_info, NO_FUNCTION, "Status inquiries.", &cmdlist);
  add_cmd ("files", class_files, NO_FUNCTION, "Specifying and examining files.", &cmdlist);
  add_cmd ("breakpoints", class_breakpoint, NO_FUNCTION, "Making program stop at certain points.", &cmdlist);
  add_cmd ("data", class_vars, NO_FUNCTION, "Examining data.", &cmdlist);
  add_cmd ("stack", class_stack, NO_FUNCTION, "Examining the stack.\n\
The stack is made up of stack frames.  Gdb assigns numbers to stack frames\n\
counting from zero for the innermost (currently executing) frame.\n\n\
At any time gdb identifies one frame as the \"selected\" frame.\n\
Variable lookups are done with respect to the selected frame.\n\
When the program being debugged stops, gdb selects the innermost frame.\n\
The commands below can be used to select other frames by number or address.",
	   &cmdlist);
  add_cmd ("running", class_run, NO_FUNCTION, "Running the program.", &cmdlist);

  add_com ("pwd", class_files, pwd_command,
	   "Print working directory.  This is used for your program as well.");
  c = add_cmd ("cd", class_files, cd_command,
	   "Set working directory to DIR for debugger and program being debugged.\n\
The change does not take effect for the program being debugged\n\
until the next time it is started.", &cmdlist);
  c->completer = filename_completer;

  add_show_from_set
    (add_set_cmd ("prompt", class_support, var_string, (char *)&prompt,
	   "Set gdb's prompt",
	   &setlist),
     &showlist);
  
  add_com ("echo", class_support, echo_command,
	   "Print a constant string.  Give string as argument.\n\
C escape sequences may be used in the argument.\n\
No newline is added at the end of the argument;\n\
use \"\\n\" if you want a newline to be printed.\n\
Since leading and trailing whitespace are ignored in command arguments,\n\
if you want to print some you must use \"\\\" before leading whitespace\n\
to be printed or after trailing whitespace.");
  add_com ("document", class_support, document_command,
	   "Document a user-defined command.\n\
Give command name as argument.  Give documentation on following lines.\n\
End with a line of just \"end\".");
  add_com ("define", class_support, define_command,
	   "Define a new command name.  Command name is argument.\n\
Definition appears on following lines, one command per line.\n\
End with a line of just \"end\".\n\
Use the \"document\" command to give documentation for the new command.\n\
Commands defined in this way do not take arguments.");

#ifdef __STDC__
  c = add_cmd ("source", class_support, source_command,
	   "Read commands from a file named FILE.\n\
Note that the file \"" GDBINIT_FILENAME "\" is read automatically in this way\n\
when gdb is started.", &cmdlist);
#else
  /* Punt file name, we can't help it easily.  */
  c = add_cmd ("source", class_support, source_command,
	   "Read commands from a file named FILE.\n\
Note that the file \".gdbinit\" is read automatically in this way\n\
when gdb is started.", &cmdlist);
#endif
  c->completer = filename_completer;

  add_com ("quit", class_support, quit_command, "Exit gdb.");
  add_com ("help", class_support, help_command, "Print list of commands.");
  add_com_alias ("q", "quit", class_support, 1);
  add_com_alias ("h", "help", class_support, 1);


  c = add_set_cmd ("verbose", class_support, var_boolean, (char *)&info_verbose,
		   "Set ",
		   &setlist),
  add_show_from_set (c, &showlist);
  c->function.sfunc = set_verbose;
  set_verbose (NULL, 0, c);
  
  add_show_from_set
    (add_set_cmd ("editing", class_support, var_boolean, (char *)&command_editing_p,
	   "Set editing of command lines as they are typed.\n\
Use \"on\" to enable to enable the editing, and \"off\" to disable it.\n\
Without an argument, command line editing is enabled.  To edit, use\n\
EMACS-like or VI-like commands like control-P or ESC.", &setlist),
     &showlist);

  add_prefix_cmd ("history", class_support, set_history,
		  "Generic command for setting command history parameters.",
		  &sethistlist, "set history ", 0, &setlist);
  add_prefix_cmd ("history", class_support, show_history,
		  "Generic command for showing command history parameters.",
		  &showhistlist, "show history ", 0, &showlist);

  add_show_from_set
    (add_set_cmd ("expansion", no_class, var_boolean, (char *)&history_expansion_p,
	   "Set history expansion on command input.\n\
Without an argument, history expansion is enabled.", &sethistlist),
     &showhistlist);

  add_show_from_set
    (add_set_cmd ("save", no_class, var_boolean, (char *)&write_history_p,
	   "Set saving of the history record on exit.\n\
Use \"on\" to enable to enable the saving, and \"off\" to disable it.\n\
Without an argument, saving is enabled.", &sethistlist),
     &showhistlist);

  c = add_set_cmd ("size", no_class, var_integer, (char *)&history_size,
		   "Set the size of the command history, \n\
ie. the number of previous commands to keep a record of.", &sethistlist);
  add_show_from_set (c, &showhistlist);
  c->function.sfunc = set_history_size_command;

  add_show_from_set
    (add_set_cmd ("filename", no_class, var_filename, (char *)&history_filename,
	   "Set the filename in which to record the command history\n\
 (the list of previous commands of which a record is kept).", &sethistlist),
     &showhistlist);

  add_show_from_set
    (add_set_cmd ("confirm", class_support, var_boolean,
		  (char *)&caution,
		  "Set whether to confirm potentially dangerous operations.",
		  &setlist),
     &showlist);

  add_prefix_cmd ("info", class_info, info_command,
        "Generic command for showing things about the program being debugged.",
		  &infolist, "info ", 0, &cmdlist);
  add_com_alias ("i", "info", class_info, 1);

  add_prefix_cmd ("show", class_info, show_command,
		  "Generic command for showing things about the debugger.",
		  &showlist, "show ", 0, &cmdlist);
  /* Another way to get at the same thing.  */
  add_info ("set", show_command, "Show all GDB settings.");

  add_cmd ("commands", no_class, show_commands,
	   "Show the the history of commands you typed.\n\
You can supply a command number to start with, or a `+' to start after\n\
the previous command number shown.",
	   &showlist);

  add_cmd ("version", no_class, show_version,
	   "Show what version of GDB this is.", &showlist);
}