[deliverable/binutils-gdb.git] / gdb / top.c

/* Top level stuff for GDB, the GNU debugger.
   Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   1996, 1997, 1998, 1999, 2000, 2001 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "gdbcmd.h"
#include "call-cmds.h"
#include "cli/cli-cmds.h"
#include "cli/cli-script.h"
#include "cli/cli-setshow.h"
#include "symtab.h"
#include "inferior.h"
#include <signal.h>
#include "target.h"
#include "breakpoint.h"
#include "gdbtypes.h"
#include "expression.h"
#include "value.h"
#include "language.h"
#include "terminal.h"           /* For job_control.  */
#include "annotate.h"
#include "completer.h"
#include "top.h"
#include "version.h"
#include "serial.h"
#include "doublest.h"
#include "gdb_assert.h"

/* readline include files */
#include <readline/readline.h>
#include <readline/history.h>

/* readline defines this.  */
#undef savestring

#include <sys/types.h>

#include <setjmp.h>

#include "event-top.h"
#include "gdb_string.h"
#include "gdb_stat.h"
#include <ctype.h>
#ifdef UI_OUT
#include "ui-out.h"
#include "cli-out.h"
#endif

/* Default command line prompt.  This is overriden in some configs. */

#ifndef DEFAULT_PROMPT
#define DEFAULT_PROMPT  "(gdb) "
#endif

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

#ifndef GDBINIT_FILENAME
#define GDBINIT_FILENAME        ".gdbinit"
#endif
char gdbinit[] = GDBINIT_FILENAME;

int inhibit_gdbinit = 0;

/* If nonzero, and GDB has been configured to be able to use windows,
   attempt to open them upon startup.  */

int use_windows = 1;

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. */

/* stdio stream that command input is being read from.  Set to stdin normally.
   Set by source_command to the file we are sourcing.  Set to NULL if we are
   executing a user-defined command or interacting via a GUI.  */

FILE *instream;

/* Current working directory.  */

char *current_directory;

/* The directory name is actually stored here (usually).  */
char gdb_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) (FILE *, char *);

int epoch_interface;
int xgdb_verbose;

/* gdb prints this when reading a command interactively */
static char *gdb_prompt_string; /* the global prompt string */

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

char *line;
int linesize = 100;

/* Nonzero if the current command is modified by "server ".  This
   affects things like recording into the command history, commands
   repeating on RETURN, etc.  This is so a user interface (emacs, GUI,
   whatever) can issue its own commands and also send along commands
   from the user, and have the user not notice that the user interface
   is issuing commands too.  */
int server_command;

/* Baud rate specified for talking to serial target systems.  Default
   is left as -1, so targets can choose their own defaults.  */
/* FIXME: This means that "show remotebaud" and gr_files_info can print -1
   or (unsigned int)-1.  This is a Bad User Interface.  */

int baud_rate = -1;

/* Timeout limit for response from target. */

/* The default value has been changed many times over the years.  It 
   was originally 5 seconds.  But that was thought to be a long time 
   to sit and wait, so it was changed to 2 seconds.  That was thought
   to be plenty unless the connection was going through some terminal 
   server or multiplexer or other form of hairy serial connection.

   In mid-1996, remote_timeout was moved from remote.c to top.c and 
   it began being used in other remote-* targets.  It appears that the
   default was changed to 20 seconds at that time, perhaps because the
   Hitachi E7000 ICE didn't always respond in a timely manner.

   But if 5 seconds is a long time to sit and wait for retransmissions,
   20 seconds is far worse.  This demonstrates the difficulty of using 
   a single variable for all protocol timeouts.

   As remote.c is used much more than remote-e7000.c, it was changed 
   back to 2 seconds in 1999. */

int remote_timeout = 2;

/* Non-zero tells remote* modules to output debugging info.  */

int remote_debug = 0;

/* Non-zero means the target is running. Note: this is different from
   saying that there is an active target and we are stopped at a
   breakpoint, for instance. This is a real indicator whether the
   target is off and running, which gdb is doing something else. */
int target_executing = 0;

/* Level of control structure.  */
static int control_level;

/* 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 (int);
#endif
#endif

/* Hooks for alternate command interfaces.  */

/* Called after most modules have been initialized, but before taking users
   command file.  */

void (*init_ui_hook) (char *argv0);

/* This hook is called from within gdb's many mini-event loops which could
   steal control from a real user interface's event loop. It returns
   non-zero if the user is requesting a detach, zero otherwise. */

int (*ui_loop_hook) (int);

/* Called instead of command_loop at top level.  Can be invoked via
   return_to_top_level.  */

void (*command_loop_hook) (void);


/* Called from print_frame_info to list the line we stopped in.  */

void (*print_frame_info_listing_hook) (struct symtab * s, int line,
                                       int stopline, int noerror);
/* Replaces most of query.  */

int (*query_hook) (const char *, va_list);

/* Replaces most of warning.  */

void (*warning_hook) (const char *, va_list);

/* These three functions support getting lines of text from the user.  They
   are used in sequence.  First readline_begin_hook is called with a text
   string that might be (for example) a message for the user to type in a
   sequence of commands to be executed at a breakpoint.  If this function
   calls back to a GUI, it might take this opportunity to pop up a text
   interaction window with this message.  Next, readline_hook is called
   with a prompt that is emitted prior to collecting the user input.
   It can be called multiple times.  Finally, readline_end_hook is called
   to notify the GUI that we are done with the interaction window and it
   can close it. */

void (*readline_begin_hook) (char *, ...);
char *(*readline_hook) (char *);
void (*readline_end_hook) (void);

/* Called as appropriate to notify the interface of the specified breakpoint
   conditions.  */

void (*create_breakpoint_hook) (struct breakpoint * bpt);
void (*delete_breakpoint_hook) (struct breakpoint * bpt);
void (*modify_breakpoint_hook) (struct breakpoint * bpt);

/* Called as appropriate to notify the interface that we have attached
   to or detached from an already running process. */

void (*attach_hook) (void);
void (*detach_hook) (void);

/* Called during long calculations to allow GUI to repair window damage, and to
   check for stop buttons, etc... */

void (*interactive_hook) (void);

/* Called when the registers have changed, as a hint to a GUI
   to minimize window update. */

void (*registers_changed_hook) (void);

/* Tell the GUI someone changed the register REGNO. -1 means
   that the caller does not know which register changed or
   that several registers have changed (see value_assign). */
void (*register_changed_hook) (int regno);

/* Tell the GUI someone changed LEN bytes of memory at ADDR */
void (*memory_changed_hook) (CORE_ADDR addr, int len);

/* Called when going to wait for the target.  Usually allows the GUI to run
   while waiting for target events.  */

ptid_t (*target_wait_hook) (ptid_t ptid,
                            struct target_waitstatus * status);

/* Used by UI as a wrapper around command execution.  May do various things
   like enabling/disabling buttons, etc...  */

void (*call_command_hook) (struct cmd_list_element * c, char *cmd,
                           int from_tty);

/* Called after a `set' command has finished.  Is only run if the
   `set' command succeeded.  */

void (*set_hook) (struct cmd_list_element * c);

/* Called when the current thread changes.  Argument is thread id.  */

void (*context_hook) (int id);

/* Takes control from error ().  Typically used to prevent longjmps out of the
   middle of the GUI.  Usually used in conjunction with a catch routine.  */

NORETURN void (*error_hook) (void) ATTR_NORETURN;
\f

/* One should use catch_errors rather than manipulating these
   directly.  */
#if defined(HAVE_SIGSETJMP)
#define SIGJMP_BUF              sigjmp_buf
#define SIGSETJMP(buf)          sigsetjmp((buf), 1)
#define SIGLONGJMP(buf,val)     siglongjmp((buf), (val))
#else
#define SIGJMP_BUF              jmp_buf
#define SIGSETJMP(buf)          setjmp(buf)
#define SIGLONGJMP(buf,val)     longjmp((buf), (val))
#endif

/* Where to go for return_to_top_level.  */
static SIGJMP_BUF *catch_return;

/* Return for reason REASON to the nearest containing catch_errors().  */

NORETURN void
return_to_top_level (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);
  if (event_loop_p && target_can_async_p () && !target_executing)
    do_exec_cleanups (ALL_CLEANUPS);
  if (event_loop_p && sync_execution)
    do_exec_error_cleanups (ALL_CLEANUPS);

  if (annotation_level > 1)
    switch (reason)
      {
      case RETURN_QUIT:
        annotate_quit ();
        break;
      case RETURN_ERROR:
        annotate_error ();
        break;
      }

  /* Jump to the containing catch_errors() call, communicating REASON
     to that call via setjmp's return value.  Note that REASON can't
     be zero, by definition in defs.h. */

  (NORETURN void) SIGLONGJMP (*catch_return, (int) reason);
}

/* Call FUNC() with args FUNC_UIOUT and FUNC_ARGS, catching any
   errors.  Set FUNC_CAUGHT to an ``enum return_reason'' if the
   function is aborted (using return_to_top_level() or zero if the
   function returns normally.  Set FUNC_VAL to the value returned by
   the function or 0 if the function was aborted.

   Must not be called with immediate_quit in effect (bad things might
   happen, say we got a signal in the middle of a memcpy to quit_return).
   This is an OK restriction; with very few exceptions immediate_quit can
   be replaced by judicious use of QUIT.

   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.  */

/* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
   error() et.al. could maintain a set of flags that indicate the the
   current state of each of the longjmp buffers.  This would give the
   longjmp code the chance to detect a longjmp botch (before it gets
   to longjmperror()).  Prior to 1999-11-05 this wasn't possible as
   code also randomly used a SET_TOP_LEVEL macro that directly
   initialize the longjmp buffers. */

/* MAYBE: cagney/1999-11-05: Should the catch_errors and cleanups code
   be consolidated into a single file instead of being distributed
   between utils.c and top.c? */

static void
catcher (catch_exceptions_ftype *func,
         struct ui_out *func_uiout,
         void *func_args,
         int *func_val,
         enum return_reason *func_caught,
         char *errstring,
         return_mask mask)
{
  SIGJMP_BUF *saved_catch;
  SIGJMP_BUF catch;
  struct cleanup *saved_cleanup_chain;
  char *saved_error_pre_print;
  char *saved_quit_pre_print;
  struct ui_out *saved_uiout;

  /* Return value from SIGSETJMP(): enum return_reason if error or
     quit caught, 0 otherwise. */
  int caught;

  /* Return value from FUNC(): Hopefully non-zero. Explicitly set to
     zero if an error quit was caught.  */
  int val;

  /* Override error/quit messages during FUNC. */

  saved_error_pre_print = error_pre_print;
  saved_quit_pre_print = quit_pre_print;

  if (mask & RETURN_MASK_ERROR)
    error_pre_print = errstring;
  if (mask & RETURN_MASK_QUIT)
    quit_pre_print = errstring;

  /* Override the global ``struct ui_out'' builder.  */

  saved_uiout = uiout;
  uiout = func_uiout;

  /* Prevent error/quit during FUNC from calling cleanups established
     prior to here. */

  saved_cleanup_chain = save_cleanups ();

  /* Call FUNC, catching error/quit events. */

  saved_catch = catch_return;
  catch_return = &catch;
  caught = SIGSETJMP (catch);
  if (!caught)
    val = (*func) (func_uiout, func_args);
  else
    val = 0;
  catch_return = saved_catch;

  /* FIXME: cagney/1999-11-05: A correct FUNC implementation will
     clean things up (restoring the cleanup chain) to the state they
     were just prior to the call.  Unfortunately, many FUNC's are not
     that well behaved.  This could be fixed by adding either a
     do_cleanups call (to cover the problem) or an assertion check to
     detect bad FUNCs code. */

  /* Restore the cleanup chain, the error/quit messages, and the uiout
     builder, to their original states. */

  restore_cleanups (saved_cleanup_chain);

  uiout = saved_uiout;

  if (mask & RETURN_MASK_QUIT)
    quit_pre_print = saved_quit_pre_print;
  if (mask & RETURN_MASK_ERROR)
    error_pre_print = saved_error_pre_print;

  /* Return normally if no error/quit event occurred or this catcher
     can handle this exception.  The caller analyses the func return
     values.  */

  if (!caught || (mask & RETURN_MASK (caught)))
    {
      *func_val = val;
      *func_caught = caught;
      return;
    }

  /* The caller didn't request that the event be caught, relay the
     event to the next containing catch_errors(). */

  return_to_top_level (caught);
}

int
catch_exceptions (struct ui_out *uiout,
                  catch_exceptions_ftype *func,
                  void *func_args,
                  char *errstring,
                  return_mask mask)
{
  int val;
  enum return_reason caught;
  catcher (func, uiout, func_args, &val, &caught, errstring, mask);
  gdb_assert (val >= 0);
  gdb_assert (caught <= 0);
  if (caught < 0)
    return caught;
  return val;
}

struct catch_errors_args
{
  catch_errors_ftype *func;
  void *func_args;
};

int
do_catch_errors (struct ui_out *uiout, void *data)
{
  struct catch_errors_args *args = data;
  return args->func (args->func_args);
}

int
catch_errors (catch_errors_ftype *func, void *func_args, char *errstring,
              return_mask mask)
{
  int val;
  enum return_reason caught;
  struct catch_errors_args args;
  args.func = func;
  args.func_args = func_args;
  catcher (do_catch_errors, uiout, &args, &val, &caught, errstring, mask);
  if (caught != 0)
    return 0;
  return val;
}

struct captured_command_args
  {
    catch_command_errors_ftype *command;
    char *arg;
    int from_tty;
  };

static int
do_captured_command (void *data)
{
  struct captured_command_args *context = data;
  context->command (context->arg, context->from_tty);
  /* FIXME: cagney/1999-11-07: Technically this do_cleanups() call
     isn't needed.  Instead an assertion check could be made that
     simply confirmed that the called function correctly cleaned up
     after itself.  Unfortunately, old code (prior to 1999-11-04) in
     main.c was calling SET_TOP_LEVEL(), calling the command function,
     and then *always* calling do_cleanups().  For the moment we
     remain ``bug compatible'' with that old code..  */
  do_cleanups (ALL_CLEANUPS);
  return 1;
}

int
catch_command_errors (catch_command_errors_ftype * command,
                      char *arg, int from_tty, return_mask mask)
{
  struct captured_command_args args;
  args.command = command;
  args.arg = arg;
  args.from_tty = from_tty;
  return catch_errors (do_captured_command, &args, "", mask);
}


/* Handler for SIGHUP.  */

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

/* NOTE 1999-04-29: This function will be static again, once we modify
   gdb to use the event loop as the default command loop and we merge
   event-top.c into this file, top.c */
/* static */ int
quit_cover (void *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;
}

static void
disconnect (int signo)
{
  catch_errors (quit_cover, NULL,
              "Could not kill the program being debugged", RETURN_MASK_ALL);
  signal (SIGHUP, SIG_DFL);
  kill (getpid (), SIGHUP);
}
#endif /* defined SIGHUP */
\f
/* Line number we are currently in in a file which is being sourced.  */
/* NOTE 1999-04-29: This variable will be static again, once we modify
   gdb to use the event loop as the default command loop and we merge
   event-top.c into this file, top.c */
/* static */ int source_line_number;

/* Name of the file we are sourcing.  */
/* NOTE 1999-04-29: This variable will be static again, once we modify
   gdb to use the event loop as the default command loop and we merge
   event-top.c into this file, top.c */
/* static */ char *source_file_name;

/* Buffer containing the error_pre_print used by the source stuff.
   Malloc'd.  */
/* NOTE 1999-04-29: This variable will be static again, once we modify
   gdb to use the event loop as the default command loop and we merge
   event-top.c into this file, top.c */
/* static */ char *source_error;
static int source_error_allocated;

/* Something to glom on to the start of error_pre_print if source_file_name
   is set.  */
/* NOTE 1999-04-29: This variable will be static again, once we modify
   gdb to use the event loop as the default command loop and we merge
   event-top.c into this file, top.c */
/* static */ char *source_pre_error;

/* Clean up on error during a "source" command (or execution of a
   user-defined command).  */

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

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

  cleanups = make_cleanup (do_restore_instream_cleanup, instream);
  instream = stream;
  command_loop ();
  do_cleanups (cleanups);
}
\f
void (*pre_init_ui_hook) (void);

#ifdef __MSDOS__
void
do_chdir_cleanup (void *old_dir)
{
  chdir (old_dir);
  xfree (old_dir);
}
#endif

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

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

  /* Force cleanup of any alloca areas if using C alloca instead of
     a builtin alloca.  */
  alloca (0);

  /* This can happen when command_line_input hits end of file.  */
  if (p == NULL)
    return;

  serial_log_command (p);

  while (*p == ' ' || *p == '\t')
    p++;
  if (*p)
    {
      char *arg;
      line = p;

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

      /* If the target is running, we allow only a limited set of
         commands. */
      if (event_loop_p && target_can_async_p () && target_executing)
        if (!strcmp (c->name, "help")
            && !strcmp (c->name, "pwd")
            && !strcmp (c->name, "show")
            && !strcmp (c->name, "stop"))
          error ("Cannot execute this command while the target is running.");

      /* Pass null arg rather than an empty one.  */
      arg = *p ? p : 0;

      /* Clear off trailing whitespace, except for set and complete command.  */
      if (arg
          && c->type != set_cmd
          && !is_complete_command (c->function.cfunc))
        {
          p = arg + strlen (arg) - 1;
          while (p >= arg && (*p == ' ' || *p == '\t'))
            p--;
          *(p + 1) = '\0';
        }

      /* If this command has been pre-hooked, run the hook first. */
      if ((c->hook_pre) && (!c->hook_in))
      {
        c->hook_in = 1; /* Prevent recursive hooking */
        execute_user_command (c->hook_pre, (char *) 0);
        c->hook_in = 0; /* Allow hook to work again once it is complete */
      }

      if (c->flags & DEPRECATED_WARN_USER)
        deprecated_cmd_warning (&line);

      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 if (call_command_hook)
        call_command_hook (c, arg, from_tty & caution);
      else
        (*c->function.cfunc) (arg, from_tty & caution);
       
      /* If this command has been post-hooked, run the hook last. */
      if ((c->hook_post) && (!c->hook_in))
      {
        c->hook_in = 1; /* Prevent recursive hooking */
        execute_user_command (c->hook_post, (char *) 0);
        c->hook_in = 0; /* allow hook to work again once it is complete */
      }

    }

  /* 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;
        }
    }
}

/* Read commands from `instream' and execute them
   until end of file or error reading instream.  */

void
command_loop (void)
{
  struct cleanup *old_chain;
  char *command;
  int stdin_is_tty = ISATTY (stdin);
  long time_at_cmd_start;
#ifdef HAVE_SBRK
  long space_at_cmd_start = 0;
#endif
  extern int display_time;
  extern int display_space;

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

      quit_flag = 0;
      if (instream == stdin && stdin_is_tty)
        reinitialize_more_filter ();
      old_chain = make_cleanup (null_cleanup, 0);

      /* Get a command-line. This calls the readline package. */
      command = command_line_input (instream == stdin ?
                                    get_prompt () : (char *) NULL,
                                    instream == stdin, "prompt");
      if (command == 0)
        return;

      time_at_cmd_start = get_run_time ();

      if (display_space)
        {
#ifdef HAVE_SBRK
          extern char **environ;
          char *lim = (char *) sbrk (0);

          space_at_cmd_start = (long) (lim - (char *) &environ);
#endif
        }

      execute_command (command, instream == stdin);
      /* Do any commands attached to breakpoint we stopped at.  */
      bpstat_do_actions (&stop_bpstat);
      do_cleanups (old_chain);

      if (display_time)
        {
          long cmd_time = get_run_time () - time_at_cmd_start;

          printf_unfiltered ("Command execution time: %ld.%06ld\n",
                             cmd_time / 1000000, cmd_time % 1000000);
        }

      if (display_space)
        {
#ifdef HAVE_SBRK
          extern char **environ;
          char *lim = (char *) sbrk (0);
          long space_now = lim - (char *) &environ;
          long space_diff = space_now - space_at_cmd_start;

          printf_unfiltered ("Space used: %ld (%c%ld for this command)\n",
                             space_now,
                             (space_diff >= 0 ? '+' : '-'),
                             space_diff);
#endif
        }
    }
}

/* Read commands from `instream' and execute them until end of file or
   error reading instream. This command loop doesnt care about any
   such things as displaying time and space usage. If the user asks
   for those, they won't work. */
void
simplified_command_loop (char *(*read_input_func) (char *),
                         void (*execute_command_func) (char *, int))
{
  struct cleanup *old_chain;
  char *command;
  int stdin_is_tty = ISATTY (stdin);

  while (instream && !feof (instream))
    {
      quit_flag = 0;
      if (instream == stdin && stdin_is_tty)
        reinitialize_more_filter ();
      old_chain = make_cleanup (null_cleanup, 0);

      /* Get a command-line. */
      command = (*read_input_func) (instream == stdin ?
                                    get_prompt () : (char *) NULL);

      if (command == 0)
        return;

      (*execute_command_func) (command, instream == stdin);

      /* Do any commands attached to breakpoint we stopped at.  */
      bpstat_do_actions (&stop_bpstat);

      do_cleanups (old_chain);
    }
}
\f
/* Commands call this if they do not want to be repeated by null lines.  */

void
dont_repeat (void)
{
  if (server_command)
    return;

  /* 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;
}
\f
/* Read a line from the stream "instream" without command line editing.

   It prints PROMPT_ARG 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 (char *prompt_arg)
{
  int c;
  char *result;
  int input_index = 0;
  int result_size = 80;

  if (prompt_arg)
    {
      /* 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_unfiltered (prompt_arg, gdb_stdout);
      /* OBSOLETE #ifdef MPW */
      /* OBSOLETE          Move to a new line so the entered line doesn't have a prompt */
      /* OBSOLETE          on the front of it. */
      /* OBSOLETE       fputs_unfiltered ("\n", gdb_stdout); */
      /* OBSOLETE #endif  *//* MPW */
      gdb_flush (gdb_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)
        {
          if (input_index > 0)
            /* The last line does not end with a newline.  Return it, and
               if we are called again fgetc will still return EOF and
               we'll return NULL then.  */
            break;
          xfree (result);
          return NULL;
        }

      if (c == '\n')
#ifndef CRLF_SOURCE_FILES
        break;
#else
        {
          if (input_index > 0 && result[input_index - 1] == '\r')
            input_index--;
          break;
        }
#endif

      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;
/* NOTE 1999-04-29: This variable will be static again, once we modify
   gdb to use the event loop as the default command loop and we merge
   event-top.c into this file, top.c */
/* static */ int history_expansion_p;
static int write_history_p;
static int history_size;
static char *history_filename;

\f
#ifdef STOP_SIGNAL
static void
stop_sig (int signo)
{
#if STOP_SIGNAL == SIGTSTP
  signal (SIGTSTP, SIG_DFL);
#if HAVE_SIGPROCMASK
  {
    sigset_t zero;

    sigemptyset (&zero);
    sigprocmask (SIG_SETMASK, &zero, 0);
  }
#elif HAVE_SIGSETMASK
  sigsetmask (0);
#endif
  kill (getpid (), SIGTSTP);
  signal (SIGTSTP, stop_sig);
#else
  signal (STOP_SIGNAL, stop_sig);
#endif
  printf_unfiltered ("%s", get_prompt ());
  gdb_flush (gdb_stdout);

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

/* Initialize signal handlers. */
static void
float_handler (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.");
}

static void
do_nothing (int signo)
{
  /* Under System V the default disposition of a signal is reinstated after
     the signal is caught and delivered to an application process.  On such
     systems one must restore the replacement signal handler if one wishes
     to continue handling the signal in one's program.  On BSD systems this
     is not needed but it is harmless, and it simplifies the code to just do
     it unconditionally. */
  signal (signo, do_nothing);
}

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

  /* If SIGTRAP was set to SIG_IGN, then the SIG_IGN will get passed
     to the inferior and breakpoints will be ignored.  */
#ifdef SIGTRAP
  signal (SIGTRAP, SIG_DFL);
#endif

  /* 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);
#ifdef SIGHUP
  if (signal (SIGHUP, do_nothing) != SIG_IGN)
    signal (SIGHUP, disconnect);
#endif
  signal (SIGFPE, float_handler);

#if defined(SIGWINCH) && defined(SIGWINCH_HANDLER)
  signal (SIGWINCH, SIGWINCH_HANDLER);
#endif
}
\f
/* 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 (char *prompt_arg, int repeat, char *annotation_suffix)
{
  static char *linebuffer = 0;
  static unsigned linelength = 0;
  register char *p;
  char *p1;
  char *rl;
  char *local_prompt = prompt_arg;
  char *nline;
  char got_eof = 0;

  /* The annotation suffix must be non-NULL.  */
  if (annotation_suffix == NULL)
    annotation_suffix = "";

  if (annotation_level > 1 && instream == stdin)
    {
      local_prompt = alloca ((prompt_arg == NULL ? 0 : strlen (prompt_arg))
                             + strlen (annotation_suffix) + 40);
      if (prompt_arg == NULL)
        local_prompt[0] = '\0';
      else
        strcpy (local_prompt, prompt_arg);
      strcat (local_prompt, "\n\032\032");
      strcat (local_prompt, annotation_suffix);
      strcat (local_prompt, "\n");
    }

  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)
    {
      if (event_loop_p)
        signal (STOP_SIGNAL, handle_stop_sig);
      else
        signal (STOP_SIGNAL, stop_sig);
    }
#endif

  while (1)
    {
      /* Make sure that all output has been output.  Some machines may let
         you get away with leaving out some of the gdb_flush, but not all.  */
      wrap_here ("");
      gdb_flush (gdb_stdout);
      gdb_flush (gdb_stderr);

      if (source_file_name != NULL)
        {
          ++source_line_number;
          sprintf (source_error,
                   "%s%s:%d: Error in sourced command file:\n",
                   source_pre_error,
                   source_file_name,
                   source_line_number);
          error_pre_print = source_error;
        }

      if (annotation_level > 1 && instream == stdin)
        {
          printf_unfiltered ("\n\032\032pre-");
          printf_unfiltered (annotation_suffix);
          printf_unfiltered ("\n");
        }

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

      if (annotation_level > 1 && instream == stdin)
        {
          printf_unfiltered ("\n\032\032post-");
          printf_unfiltered (annotation_suffix);
          printf_unfiltered ("\n");
        }

      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++;

      xfree (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;

#define SERVER_COMMAND_LENGTH 7
  server_command =
    (p - linebuffer > SERVER_COMMAND_LENGTH)
    && STREQN (linebuffer, "server ", SERVER_COMMAND_LENGTH);
  if (server_command)
    {
      /* Note that we don't set `line'.  Between this and the check in
         dont_repeat, this insures that repeating will still do the
         right thing.  */
      *p = '\0';
      return linebuffer + SERVER_COMMAND_LENGTH;
    }

  /* 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_unfiltered ("%s\n", history_value);

          /* If there was an error, call this function again.  */
          if (expanded < 0)
            {
              xfree (history_value);
              return command_line_input (prompt_arg, repeat, annotation_suffix);
            }
          if (strlen (history_value) > linelength)
            {
              linelength = strlen (history_value) + 1;
              linebuffer = (char *) xrealloc (linebuffer, linelength);
            }
          strcpy (linebuffer, history_value);
          p = linebuffer + strlen (linebuffer);
          xfree (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 && p == linebuffer)
    return line;
  for (p1 = linebuffer; *p1 == ' ' || *p1 == '\t'; p1++);
  if (repeat && !*p1)
    return line;

  *p = 0;

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

  /* Note: lines consisting solely 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.  */
  if (*p1 == '#')
    *p1 = '\0';                 /* Found a comment. */

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

  return linebuffer;
}
\f
/* Print the GDB banner. */
void
print_gdb_version (struct ui_file *stream)
{
  /* From GNU coding standards, first line is meant to be easy for a
     program to parse, and is just canonical program name and version
     number, which starts after last space. */

#ifdef MI_OUT
  /* Print it console style until a format is defined */
  fprintf_filtered (stream, "GNU gdb %s (MI_OUT)\n", version);
#else
  fprintf_filtered (stream, "GNU gdb %s\n", version);
#endif

  /* Second line is a copyright notice. */

  fprintf_filtered (stream, "Copyright 2001 Free Software Foundation, Inc.\n");

  /* Following the copyright is a brief statement that the program is
     free software, that users are free to copy and change it on
     certain conditions, that it is covered by the GNU GPL, and that
     there is no warranty. */

  fprintf_filtered (stream, "\
GDB is free software, covered by the GNU General Public License, and you are\n\
welcome to change it and/or distribute copies of it under certain conditions.\n\
Type \"show copying\" to see the conditions.\n\
There is absolutely no warranty for GDB.  Type \"show warranty\" for details.\n");

  /* After the required info we print the configuration information. */

  fprintf_filtered (stream, "This GDB was configured as \"");
  if (!STREQ (host_name, target_name))
    {
      fprintf_filtered (stream, "--host=%s --target=%s", host_name, target_name);
    }
  else
    {
      fprintf_filtered (stream, "%s", host_name);
    }
  fprintf_filtered (stream, "\".");
}
\f
/* get_prompt: access method for the GDB prompt string.  */

#define MAX_PROMPT_SIZE 256

/*
 * int get_prompt_1 (char * buf);
 *
 * Work-horse for get_prompt (called via catch_errors).
 * Argument is buffer to hold the formatted prompt.
 *
 * Returns: 1 for success (use formatted prompt)
 *          0 for failure (use gdb_prompt_string).
 */

static int gdb_prompt_escape;

static int
get_prompt_1 (void *data)
{
  char *formatted_prompt = data;
  char *local_prompt;

  if (event_loop_p)
    local_prompt = PROMPT (0);
  else
    local_prompt = gdb_prompt_string;


  if (gdb_prompt_escape == 0)
    {
      return 0;                 /* do no formatting */
    }
  else
    /* formatted prompt */
    {
      char fmt[40], *promptp, *outp, *tmp;
      value_ptr arg_val;
      DOUBLEST doubleval;
      LONGEST longval;
      CORE_ADDR addrval;

      int i, len;
      struct type *arg_type, *elt_type;

      promptp = local_prompt;
      outp = formatted_prompt;

      while (*promptp != '\0')
        {
          int available = MAX_PROMPT_SIZE - (outp - formatted_prompt) - 1;

          if (*promptp != gdb_prompt_escape)
            {
              if (available >= 1)       /* overflow protect */
                *outp++ = *promptp++;
            }
          else
            {
              /* GDB prompt string contains escape char.  Parse for arg.
                 Two consecutive escape chars followed by arg followed by
                 a comma means to insert the arg using a default format.
                 Otherwise a printf format string may be included between
                 the two escape chars.  eg:
                 %%foo, insert foo using default format
                 %2.2f%foo,     insert foo using "%2.2f" format
                 A mismatch between the format string and the data type
                 of "foo" is an error (which we don't know how to protect
                 against).  */

              fmt[0] = '\0';    /* assume null format string */
              if (promptp[1] == gdb_prompt_escape)      /* double esc char */
                {
                  promptp += 2; /* skip past two escape chars. */
                }
              else
                {
                  /* extract format string from between two esc chars */
                  i = 0;
                  do
                    {
                      fmt[i++] = *promptp++;    /* copy format string */
                    }
                  while (i < sizeof (fmt) - 1 &&
                         *promptp != gdb_prompt_escape &&
                         *promptp != '\0');

                  if (*promptp != gdb_prompt_escape)
                    error ("Syntax error at prompt position %d",
                           promptp - local_prompt);
                  else
                    {
                      promptp++;        /* skip second escape char */
                      fmt[i++] = '\0';  /* terminate the format string */
                    }
                }

              arg_val = parse_to_comma_and_eval (&promptp);
              if (*promptp == ',')
                promptp++;      /* skip past the comma */
              arg_type = check_typedef (VALUE_TYPE (arg_val));
              switch (TYPE_CODE (arg_type))
                {
                case TYPE_CODE_ARRAY:
                  elt_type = check_typedef (TYPE_TARGET_TYPE (arg_type));
                  if (TYPE_LENGTH (arg_type) > 0 &&
                      TYPE_LENGTH (elt_type) == 1 &&
                      TYPE_CODE (elt_type) == TYPE_CODE_INT)
                    {
                      int len = TYPE_LENGTH (arg_type);

                      if (VALUE_LAZY (arg_val))
                        value_fetch_lazy (arg_val);
                      tmp = VALUE_CONTENTS (arg_val);

                      if (len > available)
                        len = available;        /* overflow protect */

                      /* FIXME: how to protect GDB from crashing
                         from bad user-supplied format string? */
                      if (fmt[0] != 0)
                        sprintf (outp, fmt, tmp);
                      else
                        strncpy (outp, tmp, len);
                      outp[len] = '\0';
                    }
                  break;
                case TYPE_CODE_PTR:
                  elt_type = check_typedef (TYPE_TARGET_TYPE (arg_type));
                  addrval = value_as_pointer (arg_val);

                  if (TYPE_LENGTH (elt_type) == 1 &&
                      TYPE_CODE (elt_type) == TYPE_CODE_INT &&
                      addrval != 0)
                    {
                      /* display it as a string */
                      char *default_fmt = "%s";
                      char *tmp;
                      int err = 0;

                      /* Limiting the number of bytes that the following call
                         will read protects us from sprintf overflow later. */
                      i = target_read_string (addrval,  /* src */
                                              &tmp,     /* dest */
                                              available,        /* len */
                                              &err);
                      if (err)  /* read failed */
                        error ("%s on target_read", safe_strerror (err));

                      tmp[i] = '\0';    /* force-terminate string */
                      /* FIXME: how to protect GDB from crashing
                         from bad user-supplied format string? */
                      sprintf (outp, fmt[0] == 0 ? default_fmt : fmt,
                               tmp);
                      xfree (tmp);
                    }
                  else
                    {
                      /* display it as a pointer */
                      char *default_fmt = "0x%x";

                      /* FIXME: how to protect GDB from crashing
                         from bad user-supplied format string? */
                      if (available >= 16 /*? */ )      /* overflow protect */
                        sprintf (outp, fmt[0] == 0 ? default_fmt : fmt,
                                 (long) addrval);
                    }
                  break;
                case TYPE_CODE_FLT:
                  {
                    char *default_fmt = "%g";

                    doubleval = value_as_double (arg_val);
                    /* FIXME: how to protect GDB from crashing
                       from bad user-supplied format string? */
                    if (available >= 16 /*? */ )        /* overflow protect */
                      sprintf (outp, fmt[0] == 0 ? default_fmt : fmt,
                               (double) doubleval);
                    break;
                  }
                case TYPE_CODE_INT:
                  {
                    char *default_fmt = "%d";

                    longval = value_as_long (arg_val);
                    /* FIXME: how to protect GDB from crashing
                       from bad user-supplied format string? */
                    if (available >= 16 /*? */ )        /* overflow protect */
                      sprintf (outp, fmt[0] == 0 ? default_fmt : fmt,
                               (long) longval);
                    break;
                  }
                case TYPE_CODE_BOOL:
                  {
                    /* no default format for bool */
                    longval = value_as_long (arg_val);
                    if (available >= 8 /*? */ )         /* overflow protect */
                      {
                        if (longval)
                          strcpy (outp, "<true>");
                        else
                          strcpy (outp, "<false>");
                      }
                    break;
                  }
                case TYPE_CODE_ENUM:
                  {
                    /* no default format for enum */
                    longval = value_as_long (arg_val);
                    len = TYPE_NFIELDS (arg_type);
                    /* find enum name if possible */
                    for (i = 0; i < len; i++)
                      if (TYPE_FIELD_BITPOS (arg_type, i) == longval)
                        break;  /* match -- end loop */

                    if (i < len)        /* enum name found */
                      {
                        char *name = TYPE_FIELD_NAME (arg_type, i);

                        strncpy (outp, name, available);
                        /* in casel available < strlen (name), */
                        outp[available] = '\0';
                      }
                    else
                      {
                        if (available >= 16 /*? */ )    /* overflow protect */
                          sprintf (outp, "%ld", (long) longval);
                      }
                    break;
                  }
                case TYPE_CODE_VOID:
                  *outp = '\0';
                  break;        /* void type -- no output */
                default:
                  error ("bad data type at prompt position %d",
                         promptp - local_prompt);
                  break;
                }
              outp += strlen (outp);
            }
        }
      *outp++ = '\0';           /* terminate prompt string */
      return 1;
    }
}

char *
get_prompt (void)
{
  static char buf[MAX_PROMPT_SIZE];

  if (catch_errors (get_prompt_1, buf, "bad formatted prompt: ",
                    RETURN_MASK_ALL))
    {
      return &buf[0];           /* successful formatted prompt */
    }
  else
    {
      /* Prompt could not be formatted.  */
      if (event_loop_p)
        return PROMPT (0);
      else
        return gdb_prompt_string;
    }
}

void
set_prompt (char *s)
{
/* ??rehrauer: I don't know why this fails, since it looks as though
   assignments to prompt are wrapped in calls to savestring...
   if (prompt != NULL)
   xfree (prompt);
 */
  if (event_loop_p)
    PROMPT (0) = savestring (s, strlen (s));
  else
    gdb_prompt_string = savestring (s, strlen (s));
}
\f

/* If necessary, make the user confirm that we should quit.  Return
   non-zero if we should quit, zero if we shouldn't.  */

int
quit_confirm (void)
{
  if (! ptid_equal (inferior_ptid, null_ptid) && target_has_execution)
    {
      char *s;

      /* This is something of a hack.  But there's no reliable way to
         see if a GUI is running.  The `use_windows' variable doesn't
         cut it.  */
      if (init_ui_hook)
        s = "A debugging session is active.\nDo you still want to close the debugger?";
      else if (attach_flag)
        s = "The program is running.  Quit anyway (and detach it)? ";
      else
        s = "The program is running.  Exit anyway? ";

      if (!query (s))
        return 0;
    }

  return 1;
}

/* Quit without asking for confirmation.  */

void
quit_force (char *args, int from_tty)
{
  int exit_code = 0;

  /* An optional expression may be used to cause gdb to terminate with the 
     value of that expression. */
  if (args)
    {
      value_ptr val = parse_and_eval (args);

      exit_code = (int) value_as_long (val);
    }

  if (! ptid_equal (inferior_ptid, null_ptid) && target_has_execution)
    {
      if (attach_flag)
        target_detach (args, from_tty);
      else
        target_kill ();
    }

  /* UDI wants this, to kill the TIP.  */
  target_close (1);

  /* Save the history information if it is appropriate to do so.  */
  if (write_history_p && history_filename)
    write_history (history_filename);

  do_final_cleanups (ALL_CLEANUPS);     /* Do any final cleanups before exiting */

  exit (exit_code);
}

/* 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 (void)
{
  return gdb_has_a_terminal () && (instream == stdin) & caution;
}
\f
/* ARGSUSED */
static void
dont_repeat_command (char *ignored, int from_tty)
{
  *line = 0;                    /* Can't call dont_repeat here because we're not
                                   necessarily reading from stdin.  */
}
\f
/* Functions to manipulate command line editing control variables.  */

/* Number of commands to print in each call to show_commands.  */
#define Hist_print 10
void
show_commands (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;

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

/* ARGSUSED */
void
show_history (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 */
void
set_verbose (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.";
    }
}

/* 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.
 */

void
init_history (void)
{
  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.  */
#ifdef __MSDOS__
      /* No leading dots in file names are allowed on MSDOS.  */
      history_filename = concat (current_directory, "/_gdb_history", NULL);
#else
      history_filename = concat (current_directory, "/.gdb_history", NULL);
#endif
    }
  read_history (history_filename);
}

static void
init_main (void)
{
  struct cmd_list_element *c;

  /* If we are running the asynchronous version,
     we initialize the prompts differently. */
  if (!event_loop_p)
    {
      gdb_prompt_string = savestring (DEFAULT_PROMPT, strlen (DEFAULT_PROMPT));
    }
  else
    {
      /* initialize the prompt stack to a simple "(gdb) " prompt or to
         whatever the DEFAULT_PROMPT is. */
      the_prompts.top = 0;
      PREFIX (0) = "";
      PROMPT (0) = savestring (DEFAULT_PROMPT, strlen (DEFAULT_PROMPT));
      SUFFIX (0) = "";
      /* Set things up for annotation_level > 1, if the user ever decides
         to use it. */
      async_annotation_suffix = "prompt";
      /* Set the variable associated with the setshow prompt command. */
      new_async_prompt = savestring (PROMPT (0), strlen (PROMPT (0)));

      /* If gdb was started with --annotate=2, this is equivalent to
         the user entering the command 'set annotate 2' at the gdb
         prompt, so we need to do extra processing. */
      if (annotation_level > 1)
        set_async_annotation_level (NULL, 0, NULL);
    }
  gdb_prompt_escape = 0;        /* default to none.  */

  /* 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 (*)()) readline_line_completion_function;
  rl_completer_word_break_characters =
                                 get_gdb_completer_word_break_characters ();
  rl_completer_quote_characters = get_gdb_completer_quote_characters ();
  rl_readline_name = "gdb";

  /* The set prompt command is different depending whether or not the
     async version is run. NOTE: this difference is going to
     disappear as we make the event loop be the default engine of
     gdb. */
  if (!event_loop_p)
    {
      add_show_from_set
        (add_set_cmd ("prompt", class_support, var_string,
                      (char *) &gdb_prompt_string, "Set gdb's prompt",
                      &setlist),
         &showlist);
    }
  else
    {
      c = add_set_cmd ("prompt", class_support, var_string,
                       (char *) &new_async_prompt, "Set gdb's prompt",
                       &setlist);
      add_show_from_set (c, &showlist);
      c->function.sfunc = set_async_prompt;
    }

  add_show_from_set
    (add_set_cmd ("prompt-escape-char", class_support, var_zinteger,
                  (char *) &gdb_prompt_escape,
                  "Set escape character for formatting of gdb's prompt",
                  &setlist),
     &showlist);

  add_com ("dont-repeat", class_support, dont_repeat_command, "Don't repeat this command.\n\
Primarily used inside of user-defined commands that should not be repeated when\n\
hitting return.");

  /* The set editing command is different depending whether or not the
     async version is run. NOTE: this difference is going to disappear
     as we make the event loop be the default engine of gdb. */
  if (!event_loop_p)
    {
      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 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);
    }
  else
    {
      c = add_set_cmd ("editing", class_support, var_boolean, (char *) &async_command_editing_p,
                       "Set editing of command lines as they are typed.\n\
Use \"on\" 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);

      add_show_from_set (c, &showlist);
      c->function.sfunc = set_async_editing_command;
    }

  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 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;

  c = 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);
  c->completer = filename_completer;
  add_show_from_set (c, &showhistlist);

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

  /* The set annotate command is different depending whether or not
     the async version is run. NOTE: this difference is going to
     disappear as we make the event loop be the default engine of
     gdb. */
  if (!event_loop_p)
    {
      c = add_set_cmd ("annotate", class_obscure, var_zinteger,
                       (char *) &annotation_level, "Set annotation_level.\n\
0 == normal;     1 == fullname (for use when running under emacs)\n\
2 == output annotated suitably for use by programs that control GDB.",
                       &setlist);
      c = add_show_from_set (c, &showlist);
    }
  else
    {
      c = add_set_cmd ("annotate", class_obscure, var_zinteger,
                       (char *) &annotation_level, "Set annotation_level.\n\
0 == normal;     1 == fullname (for use when running under emacs)\n\
2 == output annotated suitably for use by programs that control GDB.",
                       &setlist);
      add_show_from_set (c, &showlist);
      c->function.sfunc = set_async_annotation_level;
    }
  if (event_loop_p)
    {
      add_show_from_set
        (add_set_cmd ("exec-done-display", class_support, var_boolean, (char *) &exec_done_display_p,
                      "Set notification of completion for asynchronous execution commands.\n\
Use \"on\" to enable the notification, and \"off\" to disable it.", &setlist),
         &showlist);
    }
}

void
gdb_init (char *argv0)
{
  if (pre_init_ui_hook)
    pre_init_ui_hook ();

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

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

#ifdef __MSDOS__
  /* Make sure we return to the original directory upon exit, come
     what may, since the OS doesn't do that for us.  */
  make_final_cleanup (do_chdir_cleanup, xstrdup (current_directory));
#endif

  init_cmd_lists ();            /* This needs to be done first */
  initialize_targets ();        /* Setup target_terminal macros for utils.c */
  initialize_utils ();          /* Make errors and warnings possible */
  initialize_all_files ();
  initialize_current_architecture ();
  init_cli_cmds();
  init_main ();                 /* But that omits this file!  Do it now */

  /* The signal handling mechanism is different depending whether or
     not the async version is run. NOTE: in the future we plan to make
     the event loop be the default engine of gdb, and this difference
     will disappear. */
  if (event_loop_p)
    async_init_signals ();
  else
    init_signals ();

  /* 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.  */

#ifdef UI_OUT
  /* Install the default UI */
  if (!init_ui_hook)
    {
      uiout = cli_out_new (gdb_stdout);

      /* All the interpreters should have had a look at things by now.
         Initialize the selected interpreter. */
      if (interpreter_p)
        {
          fprintf_unfiltered (gdb_stderr, "Interpreter `%s' unrecognized.\n",
                              interpreter_p);
          exit (1);
        }
    }
#endif

  if (init_ui_hook)
    init_ui_hook (argv0);
}