TeX 1995 July/TeX CD-ROM July 1995 (Disc 1)(Walnut Creek)(1995).ISO/macros/texinfo/info/session.c

C/C++ Source or Header | 1994-01-28 | 107KB | 4,168 lines

/* session.c -- The user windowing interface to Info. */

/* This file is part of GNU Info, a program for reading online documentation
   stored in Info format.

   Copyright (C) 1993 Free Software Foundation, Inc.

   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, 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.

   Written by Brian Fox ([e-mail]). */

#include "info.h"
#include <sys/file.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#if defined (HAVE_SYS_TIME_H)
#  include <sys/time.h>
#  define HAVE_STRUCT_TIMEVAL
#endif /* HAVE_SYS_TIME_H */

static void info_clear_pending_input (), info_set_pending_input ();
static void info_handle_pointer ();

/* **************************************************************** */
/*                                    */
/*             Running an Info Session                */
/*                                    */
/* **************************************************************** */

/* The place that we are reading input from. */
static FILE *info_input_stream = (FILE *)NULL;

/* The last executed command. */
VFunction *info_last_executed_command = (VFunction *)NULL;

/* Becomes non-zero when 'q' is typed to an Info window. */
int quit_info_immediately = 0;

/* Array of structures describing for each window which nodes have been
   visited in that window. */
INFO_WINDOW **info_windows = (INFO_WINDOW **)NULL;

/* Where to add the next window, if we need to add one. */
static int info_windows_index = 0;

/* Number of slots allocated to INFO_WINDOWS. */
static int info_windows_slots = 0;

void remember_window_and_node (), forget_window_and_nodes ();
void initialize_info_session (), info_session ();
void display_startup_message_and_start ();

/* Begin an info session finding the nodes specified by FILENAME and NODENAMES.
   For each loaded node, create a new window.  Always split the largest of the
   available windows. */
void
begin_multiple_window_info_session (filename, nodenames)
     char *filename;
     char **nodenames;
{
  register int i;
  WINDOW *window = (WINDOW *)NULL;

  for (i = 0; nodenames[i]; i++)
    {
      NODE *node;

      node = info_get_node (filename, nodenames[i]);

      if (!node)
    break;

      /* If this is the first node, initialize the info session. */
      if (!window)
    {
      initialize_info_session (node);
      window = active_window;
    }
      else
    {
      /* Find the largest window in WINDOWS, and make that be the active
         one.  Then split it and add our window and node to the list
         of remembered windows and nodes.  Then tile the windows. */
      register WINDOW *win, *largest = (WINDOW *)NULL;
      int max_height = 0;

      for (win = windows; win; win = win->next)
        if (win->height > max_height)
          {
        max_height = win->height;
        largest = win;
          }

      if (!largest)
        {
          display_update_display (windows);
          info_error (CANT_FIND_WIND);
          info_session ();
          exit (0);
        }

      active_window = largest;
      window = window_make_window (node);
      if (window)
        {
          window_tile_windows (TILE_INTERNALS);
          remember_window_and_node (window, node);
        }
      else
        {
          display_update_display (windows);
          info_error (WIN_TOO_SMALL);
          info_session ();
          exit (0);
        }
    }
    }
  display_startup_message_and_start ();
}

/* Start an info session with INITIAL_NODE, and an error message in the echo
   area made from FORMAT and ARG. */
void
begin_info_session_with_error (initial_node, format, arg)
     NODE *initial_node;
     char *format;
     void *arg;
{
  initialize_info_session (initial_node);
  info_error (format, arg, (void *)NULL);
  info_session ();
}

/* Start an info session with INITIAL_NODE. */
void
begin_info_session (initial_node)
     NODE *initial_node;
{
  initialize_info_session (initial_node);
  display_startup_message_and_start ();
}

void
display_startup_message_and_start ()
{
  char *format;

  format = replace_in_documentation
    ("Welcome to Info version %s.  Type \"\\[get-help-window]\" for help.");

  window_message_in_echo_area (format, version_string ());
  info_session ();
}

/* Run an info session with an already initialized window and node. */
void
info_session ()
{
  terminal_prep_terminal ();
  display_update_display (windows);
  info_last_executed_command = (VFunction *)NULL;
  info_read_and_dispatch ();
  terminal_unprep_terminal ();
  close_dribble_file ();
}

/* Here is a window-location dependent event loop.  Called from the
   functions info_session (), and from read_xxx_in_echo_area (). */
void
info_read_and_dispatch ()
{
  unsigned char key;
  int done;
  done = 0;

  while (!done && !quit_info_immediately)
    {
      int lk;

      /* If we haven't just gone up or down a line, there is no
     goal column for this window. */
      if ((info_last_executed_command != info_next_line) &&
      (info_last_executed_command != info_prev_line))
    active_window->goal_column = -1;

      if (echo_area_is_active)
    {
      lk = echo_area_last_command_was_kill;
      echo_area_prep_read ();
    }

      if (!info_any_buffered_input_p ())
    display_update_display (windows);

      display_cursor_at_point (active_window);
      info_initialize_numeric_arg ();

      initialize_keyseq ();
      key = info_get_input_char ();

      /* No errors yet.  We just read a character, that's all.  Only clear
     the echo_area if it is not currently active. */
      if (!echo_area_is_active)
    window_clear_echo_area ();

      info_error_was_printed = 0;

      /* Do the selected command. */
      info_dispatch_on_key (key, active_window->keymap);

      if (echo_area_is_active)
    {
      /* Echo area commands that do killing increment the value of
         ECHO_AREA_LAST_COMMAND_WAS_KILL.  Thus, if there is no
         change in the value of this variable, the last command
         executed was not a kill command. */
      if (lk == echo_area_last_command_was_kill)
        echo_area_last_command_was_kill = 0;

      if (ea_last_executed_command == ea_newline ||
          info_aborted_echo_area)
        {
          ea_last_executed_command = (VFunction *)NULL;
          done = 1;
        }

      if (info_last_executed_command == info_quit)
        quit_info_immediately = 1;
    }
      else if (info_last_executed_command == info_quit)
    done = 1;
    }
}

/* Found in signals.c */
extern void initialize_info_signal_handler ();

/* Initialize the first info session by starting the terminal, window,
   and display systems. */
void
initialize_info_session (node)
     NODE *node;
{
  char *getenv (), *term_name;

  term_name = getenv ("TERM");
  terminal_initialize_terminal (term_name);

  if (terminal_is_dumb_p)
    {
      if (!term_name)
    term_name = "dumb";

      info_error (TERM_TOO_DUMB, term_name);
      exit (1);
    }
  terminal_clear_screen ();
  initialize_info_keymaps ();
  window_initialize_windows (screenwidth, screenheight);
  initialize_info_signal_handler ();
  display_initialize_display (screenwidth, screenheight);
  info_set_node_of_window (active_window, node);

  /* Tell the window system how to notify us when a window needs to be
     asynchronously deleted (e.g., user resizes window very small). */
  window_deletion_notifier = forget_window_and_nodes;

  /* If input has not been redirected yet, make it come from STDIN. */
  if (!info_input_stream)
    info_input_stream = stdin;

  info_windows_initialized_p = 1;
}

/* Tell Info that input is coming from the file FILENAME. */
void
info_set_input_from_file (filename)
     char *filename;
{
  FILE *stream;

  stream = fopen (filename, "r");

  if (!stream)
    return;

  if (info_input_stream != stdin)
    fclose (info_input_stream);

  info_input_stream = stream;

  if (stream != stdin)
    display_inhibited = 1;
}

/* Return the INFO_WINDOW containing WINDOW, or NULL if there isn't one. */
static INFO_WINDOW *
get_info_window_of_window (window)
     WINDOW *window;
{
  register int i;
  INFO_WINDOW *info_win = (INFO_WINDOW *)NULL;

  for (i = 0; info_windows && (info_win = info_windows[i]); i++)
    if (info_win->window == window)
      break;

  return (info_win);
}

/* Reset the remembered pagetop and point of WINDOW to WINDOW's current
   values if the window and node are the same as the current one being
   displayed. */
void
set_remembered_pagetop_and_point (window)
     WINDOW *window;
{
  INFO_WINDOW *info_win;

  info_win = get_info_window_of_window (window);

  if (!info_win)
    return;

  if (info_win->nodes_index &&
      (info_win->nodes[info_win->current] == window->node))
    {
      info_win->pagetops[info_win->current] = window->pagetop;
      info_win->points[info_win->current] = window->point;
    }
}

void
remember_window_and_node (window, node)
     WINDOW *window;
     NODE *node;
{
  INFO_WINDOW *info_win;

  /* See if we already have this window in our list. */
  info_win = get_info_window_of_window (window);

  /* If the window wasn't already on our list, then make a new entry. */
  if (!info_win)
    {
      info_win = (INFO_WINDOW *)xmalloc (sizeof (INFO_WINDOW));
      info_win->window = window;
      info_win->nodes = (NODE **)NULL;
      info_win->pagetops = (int *)NULL;
      info_win->points = (long *)NULL;
      info_win->current = 0;
      info_win->nodes_index = 0;
      info_win->nodes_slots = 0;

      add_pointer_to_array (info_win, info_windows_index, info_windows,
                info_windows_slots, 10, INFO_WINDOW *);
    }

  /* If this node, the current pagetop, and the current point are the
     same as the last saved node and pagetop, don't really add this to
     the list of history nodes. */
  {
    int ni = info_win->nodes_index - 1;

    if ((ni != -1) &&
    (info_win->nodes[ni]->contents == node->contents) &&
    (info_win->pagetops[ni] == window->pagetop) &&
    (info_win->points[ni] == window->point))
    return;
  }

  /* Remember this node, the currently displayed pagetop, and the current
     location of point in this window.  Because we are updating pagetops
     and points as well as nodes, it is more efficient to avoid the
     add_pointer_to_array macro here. */
  if (info_win->nodes_index + 2 >= info_win->nodes_slots)
    {
      info_win->nodes = (NODE **)
    xrealloc (info_win->nodes,
          (info_win->nodes_slots += 20) * sizeof (NODE *));

      info_win->pagetops = (int *)
    xrealloc (info_win->pagetops, info_win->nodes_slots * sizeof (int));

      info_win->points = (long *)
    xrealloc (info_win->points, info_win->nodes_slots * sizeof (long));
    }

  info_win->nodes[info_win->nodes_index] = node;
  info_win->pagetops[info_win->nodes_index] = window->pagetop;
  info_win->points[info_win->nodes_index] = window->point;
  info_win->current = info_win->nodes_index++;
  info_win->nodes[info_win->nodes_index] = (NODE *)NULL;
  info_win->pagetops[info_win->nodes_index] = 0;
  info_win->points[info_win->nodes_index] = 0;
}

#define DEBUG_FORGET_WINDOW_AND_NODES
#if defined (DEBUG_FORGET_WINDOW_AND_NODES)
static void
consistency_check_info_windows ()
{
  register int i;
  INFO_WINDOW *info_win;

  for (i = 0; i < info_windows_index; i++)
    {
      WINDOW *win;

      for (win = windows; win; win = win->next)
    if (win == info_windows[i]->window)
      break;

      if (!win)
    abort ();
    }
}
#endif /* DEBUG_FORGET_WINDOW_AND_NODES */

/* Remove WINDOW and its associated list of nodes from INFO_WINDOWS. */
void
forget_window_and_nodes (window)
     WINDOW *window;
{
  register int i;
  INFO_WINDOW *info_win = (INFO_WINDOW *)NULL;

  for (i = 0; info_windows && (info_win = info_windows[i]); i++)
    if (info_win->window == window)
      break;

  /* If we found the window to forget, then do so. */
  if (info_win)
    {
      while (i < info_windows_index)
    info_windows[i] = info_windows[++i];

      info_windows_index--;
      info_windows[info_windows_index] = (INFO_WINDOW *)NULL;

      if (info_win->nodes)
    {
      for (i = 0; info_win->nodes[i]; i++)
        if (internal_info_node_p (info_win->nodes[i]))
          free (info_win->nodes[i]);
      free (info_win->nodes);

      maybe_free (info_win->pagetops);
      maybe_free (info_win->points);
    }

      free (info_win);
    }
#if defined (DEBUG_FORGET_WINDOW_AND_NODES)
  consistency_check_info_windows ();
#endif /* DEBUG_FORGET_WINDOW_AND_NODES */
}

/* Set WINDOW to show NODE.  Remember the new window in our list of Info
   windows.  If we are doing automatic footnote display, also try to display
   the footnotes for this window. */
void
info_set_node_of_window (window, node)
     WINDOW *window;
     NODE *node;
{
  /* Put this node into the window. */
  window_set_node_of_window (window, node);

  /* Remember this node and window in our list of info windows. */
  remember_window_and_node (window, node);

  /* If doing auto-footnote display/undisplay, show the footnotes belonging
     to this window's node. */
  if (auto_footnotes_p)
    info_get_or_remove_footnotes (window);
}


/* **************************************************************** */
/*                                    */
/*               Info Movement Commands                */
/*                                    */
/* **************************************************************** */

/* Change the pagetop of WINDOW to DESIRED_TOP, perhaps scrolling the screen
   to do so. */
void
set_window_pagetop (window, desired_top)
     WINDOW *window;
     int desired_top;
{
  int point_line, old_pagetop;

  if (desired_top < 0)
    desired_top = 0;
  else if (desired_top > window->line_count)
    desired_top = window->line_count - 1;

  if (window->pagetop == desired_top)
    return;

  old_pagetop = window->pagetop;
  window->pagetop = desired_top;

  /* Make sure that point appears in this window. */
  point_line = window_line_of_point (window);
  if ((point_line < window->pagetop) ||
      ((point_line - window->pagetop) > window->height - 1))
    window->point =
      window->line_starts[window->pagetop] - window->node->contents;

  window->flags |= W_UpdateWindow;

  /* Find out which direction to scroll, and scroll the window in that
     direction.  Do this only if there would be a savings in redisplay
     time.  This is true if the amount to scroll is less than the height
     of the window, and if the number of lines scrolled would be greater
     than 10 % of the window's height. */
  if (old_pagetop < desired_top)
    {
      int start, end, amount;

      amount = desired_top - old_pagetop;

      if ((amount >= window->height) ||
      (((window->height - amount) * 10) < window->height))
    return;

      start = amount + window->first_row;
      end = window->height + window->first_row;

      display_scroll_display (start, end, -amount);
    }
  else
    {
      int start, end, amount;

      amount = old_pagetop - desired_top;

      if ((amount >= window->height) ||
      (((window->height - amount) * 10) < window->height))
    return;

      start = window->first_row;
      end = (window->first_row + window->height) - amount;
      display_scroll_display (start, end, amount);
    }
}

/* Immediately make WINDOW->point visible on the screen, and move the
   terminal cursor there. */
static void
info_show_point (window)
     WINDOW *window;
{
  int old_pagetop;

  old_pagetop = window->pagetop;
  window_adjust_pagetop (window);
  if (old_pagetop != window->pagetop)
    {
      int new_pagetop;

      new_pagetop = window->pagetop;
      window->pagetop = old_pagetop;
      set_window_pagetop (window, new_pagetop);
    }

  if (window->flags & W_UpdateWindow)
    display_update_one_window (window);

  display_cursor_at_point (window);
}

/* Move WINDOW->point from OLD line index to NEW line index. */
static void
move_to_new_line (old, new, window)
     int old, new;
     WINDOW *window;
{
  if (old == -1)
    {
      info_error (CANT_FIND_POINT);
    }
  else
    {
      int goal;

      if (new >= window->line_count || new < 0)
    return;

      goal = window_get_goal_column (window);
      window->goal_column = goal;

      window->point = window->line_starts[new] - window->node->contents;
      window->point += window_chars_to_goal (window->line_starts[new], goal);
      info_show_point (window);
    }
}

/* Move WINDOW's point down to the next line if possible. */
DECLARE_INFO_COMMAND (info_next_line, "Move down to the next line")
{
  int old_line, new_line;

  if (count < 0)
    info_prev_line (window, -count, key);
  else
    {
      old_line = window_line_of_point (window);
      new_line = old_line + count;
      move_to_new_line (old_line, new_line, window);
    }
}

/* Move WINDOW's point up to the previous line if possible. */
DECLARE_INFO_COMMAND (info_prev_line, "Move up to the previous line")
{
  int old_line, new_line;

  if (count < 0)
    info_next_line (window, -count, key);
  else
    {
      old_line = window_line_of_point (window);
      new_line = old_line - count;
      move_to_new_line (old_line, new_line, window);
    }
}

/* Move WINDOW's point to the end of the true line. */
DECLARE_INFO_COMMAND (info_end_of_line, "Move to the end of the line")
{
  register int point, len;
  register char *buffer;

  buffer = window->node->contents;
  len = window->node->nodelen;

  for (point = window->point;
       (point < len) && (buffer[point] != '\n');
       point++);

  if (point != window->point)
    {
      window->point = point;
      info_show_point (window);
    }
}

/* Move WINDOW's point to the beginning of the true line. */
DECLARE_INFO_COMMAND (info_beginning_of_line, "Move to the start of the line")
{
  register int point;
  register char *buffer;

  buffer = window->node->contents;
  point = window->point;

  for (; (point) && (buffer[point - 1] != '\n'); point--);

  /* If at a line start alreay, do nothing. */
  if (point != window->point)
    {
      window->point = point;
      info_show_point (window);
    }
}

/* Move point forward in the node. */
DECLARE_INFO_COMMAND (info_forward_char, "Move forward a character")
{
  if (count < 0)
    info_backward_char (window, -count, key);
  else
    {
      window->point += count;

      if (window->point >= window->node->nodelen)
    window->point = window->node->nodelen - 1;

      info_show_point (window);
    }
}

/* Move point backward in the node. */
DECLARE_INFO_COMMAND (info_backward_char, "Move backward a character")
{
  if (count < 0)
    info_forward_char (window, -count, key);
  else
    {
      window->point -= count;

      if (window->point < 0)
    window->point = 0;

      info_show_point (window);
    }
}

#define alphabetic(c) (islower (c) || isupper (c) || isdigit (c))

/* Move forward a word in this node. */
DECLARE_INFO_COMMAND (info_forward_word, "Move forward a word")
{
  long point;
  char *buffer;
  int end, c;

  if (count < 0)
    {
      info_backward_word (window, -count, key);
      return;
    }

  point = window->point;
  buffer = window->node->contents;
  end = window->node->nodelen;

  while (count)
    {
      if (point + 1 >= end)
    return;

      /* If we are not in a word, move forward until we are in one.
     Then, move forward until we hit a non-alphabetic character. */
      c = buffer[point];

      if (!alphabetic (c))
    {
      while (++point < end)
        {
          c = buffer[point];
          if (alphabetic (c))
        break;
        }
    }

      if (point >= end) return;

      while (++point < end)
    {
      c = buffer[point];
      if (!alphabetic (c))
        break;
    }
      --count;
    }
  window->point = point;
  info_show_point (window);
}

DECLARE_INFO_COMMAND (info_backward_word, "Move backward a word")
{
  long point;
  char *buffer;
  int c;

  if (count < 0)
    {
      info_forward_word (window, -count, key);
      return;
    }

  buffer = window->node->contents;
  point = window->point;

  while (count)
    {
      if (point == 0)
    break;

      /* Like info_forward_word (), except that we look at the
     characters just before point. */

      c = buffer[point - 1];

      if (!alphabetic (c))
    {
      while (--point)
        {
          c = buffer[point - 1];
          if (alphabetic (c))
        break;
        }
    }

      while (point)
    {
      c = buffer[point - 1];
      if (!alphabetic (c))
        break;
      else
        --point;
    }
      --count;
    }
  window->point = point;
  info_show_point (window);
}

/* Here is a list of time counter names which correspond to ordinal numbers.
   It is used to print "once" instead of "1". */
static char *counter_names[] = {
  "not at all", "once", "twice", "three", "four", "five", "six",
  (char *)NULL
};

/* Buffer used to return values from times_description (). */
static char td_buffer[50];

/* Function returns a static string fully describing the number of times
   present in COUNT. */
static char *
times_description (count)
     int count;
{
  register int i;

  td_buffer[0] = '\0';

  for (i = 0; counter_names[i]; i++)
    if (count == i)
      break;

  if (counter_names[i])
    sprintf (td_buffer, "%s%s", counter_names[i], count > 2 ? " times" : "");
  else
    sprintf (td_buffer, "%d times", count);

  return (td_buffer);
}

/* Variable controlling the behaviour of default scrolling when you are
   already at the bottom of a node.  Possible values are defined in session.h.
   The meanings are:

   IS_Continuous    Try to get first menu item, or failing that, the
            "Next:" pointer, or failing that, the "Up:" and
            "Next:" of the up.
   IS_NextOnly        Try to get "Next:" menu item.
   IS_PageOnly        Simply give up at the bottom of a node. */

int info_scroll_behaviour = IS_Continuous;

/* Choices used by the completer when reading a value for the user-visible
   variable "scroll-behaviour". */
char *info_scroll_choices[] = {
  "Continuous", "Next Only", "Page Only", (char *)NULL
};

/* Move to 1st menu item, Next, Up/Next, or error in this window. */
static void
forward_move_node_structure (window, behaviour)
     WINDOW *window;
     int behaviour;
{
  switch (behaviour)
    {
    case IS_PageOnly:
      info_error (AT_NODE_BOTTOM);
      break;

    case IS_NextOnly:
      info_next_label_of_node (window->node);
      if (!info_parsed_nodename && !info_parsed_filename)
    info_error ("No \"Next\" pointer for this node.");
      else
    {
      window_message_in_echo_area ("Following \"Next\" node...");
      info_handle_pointer ("Next", window);
    }
      break;

    case IS_Continuous:
      {
    /* First things first.  If this node contains a menu, move down
       into the menu. */
    {
      REFERENCE **menu;

      menu = info_menu_of_node (window->node);

      if (menu)
        {
          info_free_references (menu);
          window_message_in_echo_area ("Selecting first menu item...");
          info_menu_digit (window, 1, '1');
          return;
        }
    }

    /* Okay, this node does not contain a menu.  If it contains a
       "Next:" pointer, use that. */
    info_next_label_of_node (window->node);
    if (info_label_was_found)
      {
        window_message_in_echo_area ("Selecting \"Next\" node...");
        info_handle_pointer ("Next", window);
        return;
      }

    /* Okay, there wasn't a "Next:" for this node.  Move "Up:" until we
       can move "Next:".  If that isn't possible, complain that there
       are no more nodes. */
    {
      int up_counter, old_current;
      INFO_WINDOW *info_win;

      /* Remember the current node and location. */
      info_win = get_info_window_of_window (window);
      old_current = info_win->current;

      /* Back up through the "Up:" pointers until we have found a "Next:"
         that isn't the same as the first menu item found in that node. */
      up_counter = 0;
      while (!info_error_was_printed)
        {
          info_up_label_of_node (window->node);
          if (info_label_was_found)
        {
          info_handle_pointer ("Up", window);
          if (info_error_was_printed)
            continue;

          up_counter++;

          info_next_label_of_node (window->node);

          /* If no "Next" pointer, keep backing up. */
          if (!info_label_was_found)
            continue;

          /* If this node's first menu item is the same as this node's
             Next pointer, keep backing up. */
          if (!info_parsed_filename)
            {
              REFERENCE **menu;
              char *next_nodename;

              /* Remember the name of the Next node, since reading
             the menu can overwrite the contents of the
             info_parsed_xxx strings. */
              next_nodename = savestring (info_parsed_nodename);

              menu = info_menu_of_node (window->node);
              if (menu &&
              (strcmp
               (menu[0]->nodename, next_nodename) == 0))
            {
              info_free_references (menu);
              free (next_nodename);
              continue;
            }
              else
            {
              /* Restore the world to where it was before
                 reading the menu contents. */
              info_free_references (menu);
              free (next_nodename);
              info_next_label_of_node (window->node);
            }
            }

          /* This node has a "Next" pointer, and it is not the
             same as the first menu item found in this node. */
          window_message_in_echo_area
            ("Moving \"Up\" %s, then \"Next\".",
             times_description (up_counter));

          info_handle_pointer ("Next", window);
          return;
        }
          else
        {
          /* No more "Up" pointers.  Print an error, and call it
             quits. */
          register int i;

          for (i = 0; i < up_counter; i++)
            {
              info_win->nodes_index--;
              free (info_win->nodes[info_win->nodes_index]);
              info_win->nodes[info_win->nodes_index] = (NODE *)NULL;
            }
          info_win->current = old_current;
          window->node = info_win->nodes[old_current];
          window->pagetop = info_win->pagetops[old_current];
          window->point = info_win->points[old_current];
          recalculate_line_starts (window);
          window->flags |= W_UpdateWindow;
          info_error ("No more nodes.");
        }
        }
    }
    break;
      }
    }
}

/* Move Prev, Up or error in WINDOW depending on BEHAVIOUR. */
static void
backward_move_node_structure (window, behaviour)
     WINDOW *window;
     int behaviour;
{
  switch (behaviour)
    {
    case IS_PageOnly:
      info_error (AT_NODE_TOP);
      break;

    case IS_NextOnly:
      info_prev_label_of_node (window->node);
      if (!info_parsed_nodename && !info_parsed_filename)
    info_error ("No \"Prev\" for this node.");
      else
    {
      window_message_in_echo_area ("Moving \"Prev\" in this window.");
      info_handle_pointer ("Prev", window);
    }
      break;

    case IS_Continuous:
      info_prev_label_of_node (window->node);

      if (!info_parsed_nodename && !info_parsed_filename)
    {
      info_up_label_of_node (window->node);
      if (!info_parsed_nodename && !info_parsed_filename)
        info_error ("No \"Prev\" or \"Up\" for this node.");
      else
        {
          window_message_in_echo_area ("Moving \"Up\" in this window.");
          info_handle_pointer ("Up", window);
        }
    }
      else
    {
      REFERENCE **menu;
      int inhibit_menu_traversing = 0;

      /* Watch out!  If this node's Prev is the same as the Up, then
         move Up.  Otherwise, we could move Prev, and then to the last
         menu item in the Prev.  This would cause the user to loop
         through a subsection of the info file. */
      if (!info_parsed_filename && info_parsed_nodename)
        {
          char *pnode;

          pnode = savestring (info_parsed_nodename);
          info_up_label_of_node (window->node);

          if (!info_parsed_filename && info_parsed_nodename &&
          strcmp (info_parsed_nodename, pnode) == 0)
        {
          /* The nodes are the same.  Inhibit moving to the last
             menu item. */
          free (pnode);
          inhibit_menu_traversing = 1;
        }
          else
        {
          free (pnode);
          info_prev_label_of_node (window->node);
        }
        }

      /* Move to the previous node.  If this node now contains a menu,
         and we have not inhibited movement to it, move to the node
         corresponding to the last menu item. */
      window_message_in_echo_area ("Moving \"Prev\" in this window.");
      info_handle_pointer ("Prev", window);

      if (!inhibit_menu_traversing)
        {
          while (!info_error_was_printed &&
             (menu = info_menu_of_node (window->node)))
        {
          info_free_references (menu);
          window_message_in_echo_area
            ("Moving to \"Prev\"'s last menu item.");
          info_menu_digit (window, 1, '0');
        }
        }
    }
      break;
    }
}

/* Move continuously forward through the node structure of this info file. */
DECLARE_INFO_COMMAND (info_global_next_node,
              "Move forwards or down through node structure")
{
  if (count < 0)
    info_global_prev_node (window, -count, key);
  else
    {
      while (count && !info_error_was_printed)
    {
      forward_move_node_structure (window, IS_Continuous);
      count--;
    }
    }
}

/* Move continuously backward through the node structure of this info file. */
DECLARE_INFO_COMMAND (info_global_prev_node,
              "Move backwards or up through node structure")
{
  if (count < 0)
    info_global_next_node (window, -count, key);
  else
    {
      while (count && !info_error_was_printed)
    {
      backward_move_node_structure (window, IS_Continuous);
      count--;
    }
    }
}

/* Show the next screen of WINDOW's node. */
DECLARE_INFO_COMMAND (info_scroll_forward, "Scroll forward in this window")
{
  if (count < 0)
    info_scroll_backward (window, -count, key);
  else
    {
      int desired_top;

      /* Without an explicit numeric argument, scroll the bottom two
     lines to the top of this window,  Or, if at bottom of window,
     and the user wishes to scroll through nodes get the "Next" node
     for this window. */
      if (!info_explicit_arg && count == 1)
    {
      desired_top = window->pagetop + (window->height - 2);

      /* If there are no more lines to scroll here, error, or get
         another node, depending on INFO_SCROLL_BEHAVIOUR. */
      if (desired_top > window->line_count)
        {
          int behaviour = info_scroll_behaviour;

          /* Here is a hack.  If the key being used is not SPC, do the
         PageOnly behaviour. */
          if (key != SPC && key != DEL)
        behaviour = IS_PageOnly;

          forward_move_node_structure (window, behaviour);
          return;
        }
    }
      else
    desired_top = window->pagetop + count;

      if (desired_top >= window->line_count)
    desired_top = window->line_count - 2;

      if (window->pagetop > desired_top)
    return;
      else
    set_window_pagetop (window, desired_top);
    }
}

/* Show the previous screen of WINDOW's node. */
DECLARE_INFO_COMMAND (info_scroll_backward, "Scroll backward in this window")
{
  if (count < 0)
    info_scroll_forward (window, -count, key);
  else
    {
      int desired_top;

      /* Without an explicit numeric argument, scroll the top two lines
     to the bottom of this window, or move to the previous, or Up'th
     node. */
      if (!info_explicit_arg && count == 1)
    {
      desired_top = window->pagetop - (window->height - 2);

      if ((desired_top < 0) && (window->pagetop == 0))
        {
          int behaviour = info_scroll_behaviour;

          /* Same kind of hack as in info_scroll_forward.  If the key
         used to invoke this command is not DEL, do only the PageOnly
         behaviour. */
          if (key != DEL && key != SPC)
        behaviour = IS_PageOnly;

          backward_move_node_structure (window, behaviour);
          return;
        }
    }
      else
    desired_top = window->pagetop - count;

      if (desired_top < 0)
    desired_top = 0;

      set_window_pagetop (window, desired_top);
    }
}

/* Move to the beginning of the node. */
DECLARE_INFO_COMMAND (info_beginning_of_node, "Move to the start of this node")
{
  window->pagetop = window->point = 0;
  window->flags |= W_UpdateWindow;
}

/* Move to the end of the node. */
DECLARE_INFO_COMMAND (info_end_of_node, "Move to the end of this node")
{
  window->point = window->node->nodelen - 1;
  info_show_point (window);
}

/* **************************************************************** */
/*                                    */
/*           Commands for Manipulating Windows            */
/*                                    */
/* **************************************************************** */

/* Make the next window in the chain be the active window. */
DECLARE_INFO_COMMAND (info_next_window, "Select the next window")
{
  if (count < 0)
    {
      info_prev_window (window, -count, key);
      return;
    }

  /* If no other window, error now. */
  if (!windows->next && !echo_area_is_active)
    {
      info_error (ONE_WINDOW);
      return;
    }

  while (count--)
    {
      if (window->next)
    window = window->next;
      else
    {
      if (window == the_echo_area || !echo_area_is_active)
        window = windows;
      else
        window = the_echo_area;
    }
    }

  if (active_window != window)
    {
      if (auto_footnotes_p)
    info_get_or_remove_footnotes (window);

      window->flags |= W_UpdateWindow;
      active_window = window;
    }
}

/* Make the previous window in the chain be the active window. */
DECLARE_INFO_COMMAND (info_prev_window, "Select the previous window")
{
  if (count < 0)
    {
      info_next_window (window, -count, key);
      return;
    }

  /* Only one window? */

  if (!windows->next && !echo_area_is_active)
    {
      info_error (ONE_WINDOW);
      return;
    }

  while (count--)
    {
      /* If we are in the echo area, or if the echo area isn't active and we
     are in the first window, find the last window in the chain. */
      if (window == the_echo_area ||
      (window == windows && !echo_area_is_active))
    {
      register WINDOW *win, *last;

      for (win = windows; win; win = win->next)
        last = win;

      window = last;
    }
      else
    {
      if (window == windows)
        window = the_echo_area;
      else
        window = window->prev;
    }
    }

  if (active_window != window)
    {
      if (auto_footnotes_p)
    info_get_or_remove_footnotes (window);

      window->flags |= W_UpdateWindow;
      active_window = window;
    }
}

/* Split WINDOW into two windows, both showing the same node.  If we
   are automatically tiling windows, re-tile after the split. */
DECLARE_INFO_COMMAND (info_split_window, "Split the current window")
{
  WINDOW *split, *old_active;
  int pagetop;

  /* Remember the current pagetop of the window being split.  If it doesn't
     change, we can scroll its contents around after the split. */
  pagetop = window->pagetop;

  /* Make the new window. */
  old_active = active_window;
  active_window = window;
  split = window_make_window (window->node);
  active_window = old_active;

  if (!split)
    {
      info_error (WIN_TOO_SMALL);
    }
  else
    {
#if defined (SPLIT_BEFORE_ACTIVE)
      /* Try to scroll the old window into its new postion. */
      if (pagetop == window->pagetop)
    {
      int start, end, amount;

      start = split->first_row;
      end = start + window->height;
      amount = split->height + 1;
      display_scroll_display (start, end, amount);
    }
#else /* !SPLIT_BEFORE_ACTIVE */
      /* Make sure point still appears in the active window. */
      info_show_point (window);
#endif /* !SPLIT_BEFORE_ACTIVE */

      /* If the window just split was one internal to Info, try to display
     something else in it. */
      if (internal_info_node_p (split->node))
    {
      register int i, j;
      INFO_WINDOW *iw;
      NODE *node = (NODE *)NULL;
      char *filename;

      for (i = 0; iw = info_windows[i]; i++)
        {
          for (j = 0; j < iw->nodes_index; j++)
        if (!internal_info_node_p (iw->nodes[j]))
          {
            if (iw->nodes[j]->parent)
              filename = iw->nodes[j]->parent;
            else
              filename = iw->nodes[j]->filename;

            node = info_get_node (filename, iw->nodes[j]->nodename);
            if (node)
              {
            window_set_node_of_window (split, node);
            i = info_windows_index - 1;
            break;
              }
          }
        }
    }
      split->pagetop = window->pagetop;

      if (auto_tiling_p)
    window_tile_windows (DONT_TILE_INTERNALS);
      else
    window_adjust_pagetop (split);

      remember_window_and_node (split, split->node);
    }
}

/* Delete WINDOW, forgetting the list of last visited nodes.  If we are
   automatically displaying footnotes, show or remove the footnotes
   window.  If we are automatically tiling windows, re-tile after the
   deletion. */
DECLARE_INFO_COMMAND (info_delete_window, "Delete the current window")
{
  if (!windows->next)
    {
      info_error (CANT_KILL_LAST);
    }
  else if (window->flags & W_WindowIsPerm)
    {
      info_error ("Cannot delete a permanent window");
    }
  else
    {
      info_delete_window_internal (window);

      if (auto_footnotes_p)
    info_get_or_remove_footnotes (active_window);

      if (auto_tiling_p)
    window_tile_windows (DONT_TILE_INTERNALS);
    }
}

/* Do the physical deletion of WINDOW, and forget this window and
   associated nodes. */
void
info_delete_window_internal (window)
     WINDOW *window;
{
  if (windows->next && ((window->flags & W_WindowIsPerm) == 0))
    {
      /* We not only delete the window from the display, we forget it from
     our list of remembered windows. */
      forget_window_and_nodes (window);
      window_delete_window (window);

      if (echo_area_is_active)
    echo_area_inform_of_deleted_window (window);
    }
}

/* Just keep WINDOW, deleting all others. */
DECLARE_INFO_COMMAND (info_keep_one_window, "Delete all other windows")
{
  int num_deleted;        /* The number of windows we deleted. */
  int pagetop, start, end;

  /* Remember a few things about this window.  We may be able to speed up
     redisplay later by scrolling its contents. */
  pagetop = window->pagetop;
  start = window->first_row;
  end = start + window->height;

  num_deleted = 0;

  while (1)
    {
      WINDOW *win;

      /* Find an eligible window and delete it.  If no eligible windows
     are found, we are done.  A window is eligible for deletion if
     is it not permanent, and it is not WINDOW. */
      for (win = windows; win; win = win->next)
    if (win != window && ((win->flags & W_WindowIsPerm) == 0))
      break;

      if (!win)
    break;

      info_delete_window_internal (win);
      num_deleted++;
    }

  /* Scroll the contents of this window into the right place so that the
     user doesn't have to wait any longer than necessary for redisplay. */
  if (num_deleted)
    {
      int amount;

      amount = (window->first_row - start);
      amount -= (window->pagetop - pagetop);
      display_scroll_display (start, end, amount);
    }

  window->flags |= W_UpdateWindow;
}

/* Scroll the "other" window of WINDOW. */
DECLARE_INFO_COMMAND (info_scroll_other_window, "Scroll the other window")
{
  WINDOW *other;

  /* If only one window, give up. */
  if (!windows->next)
    {
      info_error (ONE_WINDOW);
      return;
    }

  other = window->next;

  if (!other)
    other = window->prev;

  info_scroll_forward (other, count, key);
}

/* Change the size of WINDOW by AMOUNT. */
DECLARE_INFO_COMMAND (info_grow_window, "Grow (or shrink) this window")
{
  window_change_window_height (window, count);
}

/* When non-zero, tiling takes place automatically when info_split_window
   is called. */
int auto_tiling_p = 0;

/* Tile all of the visible windows. */
DECLARE_INFO_COMMAND (info_tile_windows,
    "Divide the available screen space among the visible windows")
{
  window_tile_windows (TILE_INTERNALS);
}

/* Toggle the state of this window's wrapping of lines. */
DECLARE_INFO_COMMAND (info_toggle_wrap,
          "Toggle the state of line wrapping in the current window")
{
  window_toggle_wrap (window);
}

/* **************************************************************** */
/*                                    */
/*            Info Node Commands                */
/*                                    */
/* **************************************************************** */

/* Using WINDOW for various defaults, select the node referenced by ENTRY
   in it.  If the node is selected, the window and node are remembered. */
void
info_select_reference (window, entry)
     WINDOW *window;
     REFERENCE *entry;
{
  NODE *node;
  char *filename, *nodename, *file_system_error;

  file_system_error = (char *)NULL;

  filename = entry->filename;
  if (!filename)
    filename = window->node->parent;
  if (!filename)
    filename = window->node->filename;

  if (filename)
    filename = savestring (filename);

  if (entry->nodename)
    nodename = savestring (entry->nodename);
  else
    nodename = savestring ("Top");

  node = info_get_node (filename, nodename);

  /* Try something a little weird.  If the node couldn't be found, and the
     reference was of the form "foo::", see if the entry->label can be found
     as a file, with a node of "Top". */
  if (!node)
    {
      if (info_recent_file_error)
    file_system_error = savestring (info_recent_file_error);

      if (entry->nodename && (strcmp (entry->nodename, entry->label) == 0))
    {
      node = info_get_node (entry->label, "Top");
      if (!node && info_recent_file_error)
        {
          maybe_free (file_system_error);
          file_system_error = savestring (info_recent_file_error);
        }
    }
    }

  if (!node)
    {
      if (file_system_error)
    info_error (file_system_error);
      else
    info_error (CANT_FIND_NODE, nodename);
    }

  maybe_free (file_system_error);
  maybe_free (filename);
  maybe_free (nodename);

  if (node)
    {
      set_remembered_pagetop_and_point (window);
      info_set_node_of_window (window, node);
    }
}

/* Parse the node specification in LINE using WINDOW to default the filename.
   Select the parsed node in WINDOW and remember it, or error if the node
   couldn't be found. */
static void
info_parse_and_select (line, window)
     char *line;
     WINDOW *window;
{
  REFERENCE entry;

  info_parse_node (line, DONT_SKIP_NEWLINES);

  entry.nodename = info_parsed_nodename;
  entry.filename = info_parsed_filename;
  entry.label = "*info-parse-and-select*";

  info_select_reference (window, &entry);
}

/* Given that the values of INFO_PARSED_FILENAME and INFO_PARSED_NODENAME
   are previously filled, try to get the node represented by them into
   WINDOW.  The node should have been pointed to by the LABEL pointer of
   WINDOW->node. */
static void
info_handle_pointer (label, window)
     char *label;
     WINDOW *window;
{
  if (info_parsed_filename || info_parsed_nodename)
    {
      char *filename, *nodename;
      NODE *node;

      filename = nodename = (char *)NULL;

      if (info_parsed_filename)
    filename = savestring (info_parsed_filename);
      else
    {
      if (window->node->parent)
        filename = savestring (window->node->parent);
      else if (window->node->filename)
        filename = savestring (window->node->filename);
    }

      if (info_parsed_nodename)
    nodename = savestring (info_parsed_nodename);
      else
    nodename = savestring ("Top");

      node = info_get_node (filename, nodename);

      if (node)
    {
      INFO_WINDOW *info_win;

      info_win = get_info_window_of_window (window);
      if (info_win)
        {
          info_win->pagetops[info_win->current] = window->pagetop;
          info_win->points[info_win->current] = window->point;
        }
      set_remembered_pagetop_and_point (window);
      info_set_node_of_window (window, node);
    }
      else
    {
      if (info_recent_file_error)
        info_error (info_recent_file_error);
      else
        info_error (CANT_FILE_NODE, filename, nodename);
    }

      free (filename);
      free (nodename);
    }
  else
    {
      info_error (NO_POINTER, label);
    }
}

/* Make WINDOW display the "Next:" node of the node currently being
   displayed. */
DECLARE_INFO_COMMAND (info_next_node, "Select the `Next' node")
{
  info_next_label_of_node (window->node);
  info_handle_pointer ("Next", window);
}

/* Make WINDOW display the "Prev:" node of the node currently being
   displayed. */
DECLARE_INFO_COMMAND (info_prev_node, "Select the `Prev' node")
{
  info_prev_label_of_node (window->node);
  info_handle_pointer ("Prev", window);
}

/* Make WINDOW display the "Up:" node of the node currently being
   displayed. */
DECLARE_INFO_COMMAND (info_up_node, "Select the `Up' node")
{
  info_up_label_of_node (window->node);
  info_handle_pointer ("Up", window);
}

/* Make WINDOW display the last node of this info file. */
DECLARE_INFO_COMMAND (info_last_node, "Select the last node in this file")
{
  register int i;
  FILE_BUFFER *fb = file_buffer_of_window (window);
  NODE *node = (NODE *)NULL;

  if (fb && fb->tags)
    {
      for (i = 0; fb->tags[i]; i++);
      node = info_get_node (fb->filename, fb->tags[i - 1]->nodename);
    }

  if (!node)
    info_error ("This window has no additional nodes");
  else
    {
      set_remembered_pagetop_and_point (window);
      info_set_node_of_window (window, node);
    }
}

/* Make WINDOW display the first node of this info file. */
DECLARE_INFO_COMMAND (info_first_node, "Select the first node in this file")
{
  FILE_BUFFER *fb = file_buffer_of_window (window);
  NODE *node = (NODE *)NULL;

  if (fb && fb->tags)
    node = info_get_node (fb->filename, fb->tags[0]->nodename);

  if (!node)
    info_error ("This window has no additional nodes");
  else
    {
      set_remembered_pagetop_and_point (window);
      info_set_node_of_window (window, node);
    }
}

/* Make WINDOW display the previous node displayed in this window. */
DECLARE_INFO_COMMAND (info_history_node,
              "Select the most recently selected node")
{
  INFO_WINDOW *info_win;

  /* Find the INFO_WINDOW which contains WINDOW. */
  info_win = get_info_window_of_window (window);

  if (!info_win)
    {
      info_error ("Requested window is not present!");
      return;
    }

  set_remembered_pagetop_and_point (window);
  if (!info_win->current)
    {
      if (info_win->nodes_index > 1)
    {
      window_message_in_echo_area
        ("Now wrapped around to beginning of history.");
      info_win->current = info_win->nodes_index;
    }
      else
    {
      info_error ("No earlier nodes in this window.");
      return;
    }
    }

  info_win->current--;
  window_set_node_of_window (window, info_win->nodes[info_win->current]);
  window->pagetop = info_win->pagetops[info_win->current];
  window->point   = info_win->points[info_win->current];
  window->flags |= W_UpdateWindow;
  if (auto_footnotes_p)
    info_get_or_remove_footnotes (window);
}

/* Select the last menu item in WINDOW->node. */
DECLARE_INFO_COMMAND (info_last_menu_item,
   "Select the last item in this node's menu")
{
  info_menu_digit (window, 1, '0');
}

/* Use KEY (a digit) to select the Nth menu item in WINDOW->node. */
DECLARE_INFO_COMMAND (info_menu_digit, "Select this menu item")
{
  register int i, item;
  register REFERENCE *entry, **menu;

  menu = info_menu_of_node (window->node);

  if (!menu)
    {
      info_error (NO_MENU_NODE);
      return;
    }

  /* We have the menu.  See if there are this many items in it. */
  item = key - '0';

  /* Special case.  Item "0" is the last item in this menu. */
  if (item == 0)
    for (i = 0; menu[i + 1]; i++);
  else
    {
      for (i = 0; entry = menu[i]; i++)
    if (i == item - 1)
      break;
    }

  if (menu[i])
    info_select_reference (window, menu[i]);
  else
    info_error ("There aren't %d items in this menu.", item);

  info_free_references (menu);
  return;
}

/* Read a menu or followed reference from the user defaulting to the
   reference found on the current line, and select that node.  The
   reading is done with completion.  BUILDER is the function used
   to build the list of references.  ASK_P is non-zero if the user
   should be prompted, or zero to select the default item. */
static void
info_menu_or_ref_item (window, count, key, builder, ask_p)
     WINDOW *window;
     int count;
     unsigned char key;
     REFERENCE **(*builder) ();
     int ask_p;
{
  REFERENCE **menu, *entry, *defentry = (REFERENCE *)NULL;
  char *line;

  menu = (*builder) (window->node);

  if (!menu)
    {
      if (builder == info_menu_of_node)
    info_error (NO_MENU_NODE);
      else
    info_error (NO_XREF_NODE);
      return;
    }

  /* Default the selected reference to the one which is on the line that
     point is in.  */
  {
    REFERENCE **refs = (REFERENCE **)NULL;
    int point_line;

    point_line = window_line_of_point (window);

    if (point_line != -1)
      {
    SEARCH_BINDING binding;

    binding.start = 0;
    binding.buffer = window->line_starts[point_line];
    if (window->line_starts[point_line + 1])
      binding.end = window->line_starts[point_line + 1] - binding.buffer;
    else
      binding.end =
        (window->node->contents + window->node->nodelen) - binding.buffer;
    binding.flags = 0;

    if (builder == info_menu_of_node)
      {
        if (point_line)
          {
        binding.buffer--;
        binding.end++;

        refs = info_menu_items (&binding);
          }
      }
    else
      refs = info_xrefs (&binding);

    if (refs)
      {
        if ((strcmp (refs[0]->label, "Menu") != 0) ||
        (builder == info_xrefs_of_node))
          {
        defentry = (REFERENCE *)xmalloc (sizeof (REFERENCE));
        defentry->label = savestring (refs[0]->label);
        defentry->filename = refs[0]->filename;
        defentry->nodename = refs[0]->nodename;

        if (defentry->filename)
          defentry->filename = savestring (defentry->filename);
        if (defentry->nodename)
          defentry->nodename = savestring (defentry->nodename);
          }
        info_free_references (refs);
      }
      }
  }

  /* If we are going to ask the user a question, do it now. */
  if (ask_p)
    {
      char *prompt;

      /* Build the prompt string. */
      if (defentry)
    prompt = (char *)xmalloc (20 + strlen (defentry->label));
      else
    prompt = (char *)xmalloc (20);

      if (builder == info_menu_of_node)
    {
      if (defentry)
        sprintf (prompt, "Menu item (%s): ", defentry->label);
      else
        sprintf (prompt, "Menu item: ");
    }
      else
    {
      if (defentry)
        sprintf (prompt, "Follow xref (%s): ", defentry->label);
      else
        sprintf (prompt, "Follow xref: ");
    }

      line = info_read_completing_in_echo_area (window, prompt, menu);
      free (prompt);

      window = active_window;

      /* User aborts, just quit. */
      if (!line)
    {
      maybe_free (defentry);
      info_free_references (menu);
      info_abort_key (window, 0, 0);
      return;
    }

      /* If we had a default and the user accepted it, use that. */
      if (!*line)
    {
      free (line);
      if (defentry)
        line = savestring (defentry->label);
      else
        line = (char *)NULL;
    }
    }
  else
    {
      /* Not going to ask any questions.  If we have a default entry, use
     that, otherwise return. */
      if (!defentry)
    return;
      else
    line = savestring (defentry->label);
    }

  if (line)
    {
      /* Find the selected label in the references. */
      entry = info_get_labeled_reference (line, menu);

      if (!entry && defentry)
    info_error ("The reference disappeared! (%s).", line);
      else
    {
      NODE *orig;

      orig = window->node;
      info_select_reference (window, entry);
      if ((builder == info_xrefs_of_node) && (window->node != orig))
        {
          long offset;
          long start;

          if (window->line_count > 0)
        start = window->line_starts[1] - window->node->contents;
          else
        start = 0;

          offset =
        info_target_search_node (window->node, entry->label, start);

          if (offset != -1)
        {
          window->point = offset;
          window_adjust_pagetop (window);
        }
        }
    }

      free (line);
      if (defentry)
    {
      free (defentry->label);
      maybe_free (defentry->filename);
      maybe_free (defentry->nodename);
      free (defentry);
    }
    }

  info_free_references (menu);

  if (!info_error_was_printed)
    window_clear_echo_area ();
}

/* Read a line (with completion) which is the name of a menu item,
   and select that item. */
DECLARE_INFO_COMMAND (info_menu_item, "Read a menu item and select its node")
{
  info_menu_or_ref_item (window, count, key, info_menu_of_node, 1);
}

/* Read a line (with completion) which is the name of a reference to
   follow, and select the node. */
DECLARE_INFO_COMMAND
  (info_xref_item, "Read a footnote or cross reference and select its node")
{
  info_menu_or_ref_item (window, count, key, info_xrefs_of_node, 1);
}

/* Position the cursor at the start of this node's menu. */
DECLARE_INFO_COMMAND (info_find_menu, "Move to the start of this node's menu")
{
  SEARCH_BINDING binding;
  long position;

  binding.buffer = window->node->contents;
  binding.start  = 0;
  binding.end = window->node->nodelen;
  binding.flags = S_FoldCase | S_SkipDest;

  position = search (INFO_MENU_LABEL, &binding);

  if (position == -1)
    info_error (NO_MENU_NODE);
  else
    {
      window->point = position;
      window_adjust_pagetop (window);
      window->flags |= W_UpdateWindow;
    }
}

/* Visit as many menu items as is possible, each in a separate window. */
DECLARE_INFO_COMMAND (info_visit_menu,
  "Visit as many menu items at once as possible")
{
  register int i;
  REFERENCE *entry, **menu;

  menu = info_menu_of_node (window->node);

  if (!menu)
    info_error (NO_MENU_NODE);

  for (i = 0; (!info_error_was_printed) && (entry = menu[i]); i++)
    {
      WINDOW *new;

      new = window_make_window (window->node);
      window_tile_windows (TILE_INTERNALS);

      if (!new)
    info_error (WIN_TOO_SMALL);
      else
    {
      active_window = new;
      info_select_reference (new, entry);
    }
    }
}

/* Read a line of input which is a node name, and go to that node. */
DECLARE_INFO_COMMAND (info_goto_node, "Read a node name and select it")
{
  char *line;
  NODE *node;

#define GOTO_COMPLETES
#if defined (GOTO_COMPLETES)
  /* Build a completion list of all of the known nodes. */
  {
    register int fbi, i;
    FILE_BUFFER *current;
    REFERENCE **items = (REFERENCE **)NULL;
    int items_index = 0;
    int items_slots = 0;

    current = file_buffer_of_window (window);

    for (fbi = 0; info_loaded_files && info_loaded_files[fbi]; fbi++)
      {
    FILE_BUFFER *fb;
    REFERENCE *entry;
    int this_is_the_current_fb;

    fb = info_loaded_files[fbi];
    this_is_the_current_fb = (current == fb);

    entry = (REFERENCE *)xmalloc (sizeof (REFERENCE));
    entry->filename = entry->nodename = (char *)NULL;
    entry->label = (char *)xmalloc (4 + strlen (fb->filename));
    sprintf (entry->label, "(%s)*", fb->filename);

    add_pointer_to_array
      (entry, items_index, items, items_slots, 10, REFERENCE *);

    if (fb->tags)
      {
        for (i = 0; fb->tags[i]; i++)
          {
        entry = (REFERENCE *)xmalloc (sizeof (REFERENCE));
        entry->filename = entry->nodename = (char *)NULL;
        entry->label = (char *) xmalloc
          (4 + strlen (fb->filename) + strlen (fb->tags[i]->nodename));
        sprintf (entry->label, "(%s)%s",
             fb->filename, fb->tags[i]->nodename);

        add_pointer_to_array
          (entry, items_index, items, items_slots, 100, REFERENCE *);
          }

        if (this_is_the_current_fb)
          {
        for (i = 0; fb->tags[i]; i++)
          {
            entry = (REFERENCE *)xmalloc (sizeof (REFERENCE));
            entry->filename = entry->nodename = (char *)NULL;
            entry->label = savestring (fb->tags[i]->nodename);
            add_pointer_to_array (entry, items_index, items,
                      items_slots, 100, REFERENCE *);
          }
          }
      }
      }
    line = info_read_maybe_completing (window, "Goto Node: ", items);
    info_free_references (items);
  }
#else /* !GOTO_COMPLETES */
  line = info_read_in_echo_area (window, "Goto Node: ");
#endif /* !GOTO_COMPLETES */

  /* If the user aborted, quit now. */
  if (!line)
    {
      info_abort_key (window, 0, 0);
      return;
    }

  canonicalize_whitespace (line);

  if (*line)
    info_parse_and_select (line, window);

  free (line);
  if (!info_error_was_printed)
    window_clear_echo_area ();
}

/* Move to the "Top" node in this file. */
DECLARE_INFO_COMMAND (info_top_node, "Select the node `Top' in this file")
{
  info_parse_and_select ("Top", window);
}

/* Move to the node "(dir)Top". */
DECLARE_INFO_COMMAND (info_dir_node, "Select the node `(dir)'")
{
  info_parse_and_select ("(dir)Top", window);
}

/* Try to delete the current node appearing in this window, showing the most
   recently selected node in this window. */
DECLARE_INFO_COMMAND (info_kill_node, "Kill this node")
{
  register int iw, i;
  register INFO_WINDOW *info_win;
  char *nodename = (char *)NULL;
  NODE *temp = (NODE *)NULL;

  /* Read the name of a node to kill.  The list of available nodes comes
     from the nodes appearing in the current window configuration. */
  {
    REFERENCE **menu = (REFERENCE **)NULL;
    int menu_index = 0, menu_slots = 0;
    char *default_nodename, *prompt;

    for (iw = 0; info_win = info_windows[iw]; iw++)
      {
    REFERENCE *entry;

    entry = (REFERENCE *)xmalloc (sizeof (REFERENCE));
    entry->label = savestring (info_win->window->node->nodename);
    entry->filename = entry->nodename = (char *)NULL;

    add_pointer_to_array
      (entry, menu_index, menu, menu_slots, 10, REFERENCE *);
      }

    default_nodename = savestring (active_window->node->nodename);
    prompt = (char *)xmalloc (40 + strlen (default_nodename));
    sprintf (prompt, "Kill node (%s): ", default_nodename);

    nodename = info_read_completing_in_echo_area (window, prompt, menu);
    free (prompt);
    info_free_references (menu);
    if (nodename && !*nodename)
      {
    free (nodename);
    nodename = default_nodename;
      }
    else
      free (default_nodename);
  }

  /* If there is no nodename to kill, quit now. */
  if (!nodename)
    {
      info_abort_key (window, 0, 0);
      return;
    }

  /* If there is a nodename, find it in our window list. */
  for (iw = 0; info_win = info_windows[iw]; iw++)
    if (strcmp (nodename, info_win->nodes[info_win->current]->nodename) == 0)
      break;

  if (!info_win)
    {
      if (*nodename)
    info_error ("Cannot kill the node `%s'", nodename);
      else
    window_clear_echo_area ();

      return;
    }

  /* If there are no more nodes left anywhere to view, complain and exit. */
  if (info_windows_index == 1 && info_windows[0]->nodes_index == 1)
    {
      info_error ("Cannot kill the last node");
      return;
    }

  /* INFO_WIN contains the node that the user wants to stop viewing.
     Delete this node from the list of nodes previously shown in this
     window. */
  for (i = info_win->current; i < info_win->nodes_index; i++)
    info_win->nodes[i] = info_win->nodes[i++];

  /* There is one less node in this window's history list. */
  info_win->nodes_index--;

  /* Make this window show the most recent history node. */
  info_win->current = info_win->nodes_index - 1;

  /* If there aren't any nodes left in this window, steal one from the
     next window. */
  if (info_win->current < 0)
    {
      INFO_WINDOW *stealer;
      int which, pagetop;
      long point;

      if (info_windows[iw + 1])
    stealer = info_windows[iw + 1];
      else
    stealer = info_windows[0];

      /* If the node being displayed in the next window is not the most
     recently loaded one, get the most recently loaded one. */
      if ((stealer->nodes_index - 1) != stealer->current)
    which = stealer->nodes_index - 1;

      /* Else, if there is another node behind the stealers current node,
     use that one. */
      else if (stealer->current > 0)
    which = stealer->current - 1;

      /* Else, just use the node appearing in STEALER's window. */
      else
    which = stealer->current;

      /* Copy this node. */
      {
    NODE *copy;

    temp = stealer->nodes[which];
    point = stealer->points[which];
    pagetop = stealer->pagetops[which];

    copy = (NODE *)xmalloc (sizeof (NODE));
    copy->filename = temp->filename;
    copy->parent = temp->parent;
    copy->nodename = temp->nodename;
    copy->contents = temp->contents;
    copy->nodelen = temp->nodelen;
    copy->flags = temp->flags;

    temp = copy;
      }

      window_set_node_of_window (info_win->window, temp);
      window->point = point;
      window->pagetop = pagetop;
      remember_window_and_node (info_win->window, temp);
    }
  else
    {
      temp = info_win->nodes[info_win->current];
      window_set_node_of_window (info_win->window, temp);
    }
  if (!info_error_was_printed)
    window_clear_echo_area ();
}

/* Read the name of a file and select the entire file. */
DECLARE_INFO_COMMAND (info_view_file, "Read the name of a file and select it")
{
  char *line;

  line = info_read_in_echo_area (window, "Find file: ");
  if (!line)
    {
      info_abort_key (active_window, 1, 0);
      return;
    }

  if (*line)
    {
      NODE *node;

      node = info_get_node (line, "*");
      if (!node)
    {
      if (info_recent_file_error)
        info_error (info_recent_file_error);
      else
        info_error ("Cannot find \"%s\".", line);
    }
      else
    {
      set_remembered_pagetop_and_point (active_window);
      info_set_node_of_window (window, node);
    }
      free (line);
    }

  if (!info_error_was_printed)
    window_clear_echo_area ();
}

/* **************************************************************** */
/*                                    */
/*           Dumping and Printing Nodes                */
/*                                    */
/* **************************************************************** */

#define VERBOSE_NODE_DUMPING
static void write_node_to_stream ();
static void dump_node_to_stream ();
static void initialize_dumping ();

/* Dump the nodes specified by FILENAME and NODENAMES to the file named
   in OUTPUT_FILENAME.  If DUMP_SUBNODES is non-zero, recursively dump
   the nodes which appear in the menu of each node dumped. */
void
dump_nodes_to_file (filename, nodenames, output_filename, dump_subnodes)
     char *filename;
     char **nodenames;
     char *output_filename;
     int dump_subnodes;
{
  register int i;
  FILE *output_stream;

  /* Get the stream to print the nodes to.  Special case of an output
     filename of "-" means to dump the nodes to stdout. */
  if (strcmp (output_filename, "-") == 0)
    output_stream = stdout;
  else
    output_stream = fopen (output_filename, "w");

  if (!output_stream)
    {
      info_error ("Could not create output file \"%s\".", output_filename);
      return;
    }

  /* Print each node to stream. */
  initialize_dumping ();
  for (i = 0; nodenames[i]; i++)
    dump_node_to_stream (filename, nodenames[i], output_stream, dump_subnodes);

  if (output_stream != stdout)
    fclose (output_stream);

#if defined (VERBOSE_NODE_DUMPING)
  info_error ("Done.");
#endif /* VERBOSE_NODE_DUMPING */
}

/* A place to remember already dumped nodes. */
static char **dumped_already = (char **)NULL;
static int dumped_already_index = 0;
static int dumped_already_slots = 0;

static void
initialize_dumping ()
{
  dumped_already_index = 0;
}

/* Get and print the node specified by FILENAME and NODENAME to STREAM.
   If DUMP_SUBNODES is non-zero, recursively dump the nodes which appear
   in the menu of each node dumped. */
static void
dump_node_to_stream (filename, nodename, stream, dump_subnodes)
     char *filename, *nodename;
     FILE *stream;
     int dump_subnodes;
{
  register int i;
  NODE *node;

  node = info_get_node (filename, nodename);

  if (!node)
    {
      if (info_recent_file_error)
    info_error (info_recent_file_error);
      else
    {
      if (filename && *nodename != '(')
        info_error
          (CANT_FILE_NODE, filename_non_directory (filename), nodename);
      else
        info_error (CANT_FIND_NODE, nodename);
    }
      return;
    }

  /* If we have already dumped this node, don't dump it again. */
  for (i = 0; i < dumped_already_index; i++)
    if (strcmp (node->nodename, dumped_already[i]) == 0)
      {
    free (node);
    return;
      }
  add_pointer_to_array (node->nodename, dumped_already_index, dumped_already,
            dumped_already_slots, 50, char *);

#if defined (VERBOSE_NODE_DUMPING)
  /* Maybe we should print some information about the node being output. */
  if (node->filename)
    info_error ("Writing node \"(%s)%s\"...",
        filename_non_directory (node->filename), node->nodename);
  else
    info_error ("Writing node \"%s\"...", node->nodename);
#endif /* VERBOSE_NODE_DUMPING */

  write_node_to_stream (node, stream);

  /* If we are dumping subnodes, get the list of menu items in this node,
     and dump each one recursively. */
  if (dump_subnodes)
    {
      REFERENCE **menu = (REFERENCE **)NULL;

      /* If this node is an Index, do not dump the menu references. */
      if (string_in_line ("Index", node->nodename) == -1)
    menu = info_menu_of_node (node);

      if (menu)
    {
      for (i = 0; menu[i]; i++)
        {
          /* We don't dump Info files which are different than the
         current one. */
          if (!menu[i]->filename)
        dump_node_to_stream
          (filename, menu[i]->nodename, stream, dump_subnodes);
        }
      info_free_references (menu);
    }
    }

  free (node);
}

/* Dump NODE to FILENAME.  If DUMP_SUBNODES is non-zero, recursively dump
   the nodes which appear in the menu of each node dumped. */
void
dump_node_to_file (node, filename, dump_subnodes)
     NODE *node;
     char *filename;
     int dump_subnodes;
{
  FILE *output_stream;
  char *nodes_filename;

  /* Get the stream to print this node to.  Special case of an output
     filename of "-" means to dump the nodes to stdout. */
  if (strcmp (filename, "-") == 0)
    output_stream = stdout;
  else
    output_stream = fopen (filename, "w");

  if (!output_stream)
    {
      info_error ("Could not create output file \"%s\".", filename);
      return;
    }

  if (node->parent)
    nodes_filename = node->parent;
  else
    nodes_filename = node->filename;

  initialize_dumping ();
  dump_node_to_stream
    (nodes_filename, node->nodename, output_stream, dump_subnodes);

  if (output_stream != stdout)
    fclose (output_stream);

#if defined (VERBOSE_NODE_DUMPING)
  info_error ("Done.");
#endif /* VERBOSE_NODE_DUMPING */
}

#if !defined (DEFAULT_INFO_PRINT_COMMAND)
#  define DEFAULT_INFO_PRINT_COMMAND "lpr"
#endif /* !DEFAULT_INFO_PRINT_COMMAND */

DECLARE_INFO_COMMAND (info_print_node,
 "Pipe the contents of this node through INFO_PRINT_COMMAND")
{
  print_node (window->node);
}

/* Print NODE on a printer piping it into INFO_PRINT_COMMAND. */
void
print_node (node)
     NODE *node;
{
  char *print_command, *getenv ();
  FILE *printer_pipe;

  print_command = getenv ("INFO_PRINT_COMMAND");

  if (!print_command || !*print_command)
    print_command = DEFAULT_INFO_PRINT_COMMAND;

  printer_pipe = popen (print_command, "w");

  if (!printer_pipe)
    {
      info_error ("Cannot open pipe to \"%s\".", print_command);
      return;
    }

#if defined (VERBOSE_NODE_DUMPING)
  /* Maybe we should print some information about the node being output. */
  if (node->filename)
    info_error ("Printing node \"(%s)%s\"...",
        filename_non_directory (node->filename), node->nodename);
  else
    info_error ("Printing node \"%s\"...", node->nodename);
#endif /* VERBOSE_NODE_DUMPING */

  write_node_to_stream (node, printer_pipe);
  pclose (printer_pipe);

#if defined (VERBOSE_NODE_DUMPING)
  info_error ("Done.");
#endif /* VERBOSE_NODE_DUMPING */
}

static void
write_node_to_stream (node, stream)
     NODE *node;
     FILE *stream;
{
  fwrite (node->contents, 1, node->nodelen, stream);
}

/* **************************************************************** */
/*                                    */
/*              Info Searching Commands                */
/*                                    */
/* **************************************************************** */

/* Variable controlling the garbage collection of files briefly visited
   during searches.  Such files are normally gc'ed, unless they were
   compressed to begin with.  If this variable is non-zero, it says
   to gc even those file buffer contents which had to be uncompressed. */
int gc_compressed_files = 0;

static void info_gc_file_buffers ();

static char *search_string = (char *)NULL;
static int search_string_index = 0;
static int search_string_size = 0;
static int isearch_is_active = 0;

/* Return the file buffer which belongs to WINDOW's node. */
FILE_BUFFER *
file_buffer_of_window (window)
     WINDOW *window;
{
  /* If this window has no node, then it has no file buffer. */
  if (!window->node)
    return ((FILE_BUFFER *)NULL);

  if (window->node->parent)
    return (info_find_file (window->node->parent));

  if (window->node->filename)
    return (info_find_file (window->node->filename));

  return ((FILE_BUFFER *)NULL);
}

/* Search for STRING in NODE starting at START.  Return -1 if the string
   was not found, or the location of the string if it was.  If WINDOW is
   passed as non-null, set the window's node to be NODE, its point to be
   the found string, and readjust the window's pagetop.  Final argument
   DIR says which direction to search in.  If it is positive, search
   forward, else backwards. */
long
info_search_in_node (string, node, start, window, dir)
     char *string;
     NODE *node;
     long start;
     WINDOW *window;
     int dir;
{
  SEARCH_BINDING binding;
  long offset;

  binding.buffer = node->contents;
  binding.start = start;
  binding.end = node->nodelen;
  binding.flags = S_FoldCase;

  if (dir < 0)
    {
      binding.end = 0;
      binding.flags |= S_SkipDest;
    }

  if (binding.start < 0)
    return (-1);

  /* For incremental searches, we always wish to skip past the string. */
  if (isearch_is_active)
    binding.flags |= S_SkipDest;

  offset = search (string, &binding);

  if (offset != -1 && window)
    {
      set_remembered_pagetop_and_point (window);
      if (window->node != node)
    window_set_node_of_window (window, node);
      window->point = offset;
      window_adjust_pagetop (window);
    }
  return (offset);
}

/* Search NODE, looking for the largest possible match of STRING.  Start the
   search at START.  Return the absolute position of the match, or -1, if
   no part of the string could be found. */
long
info_target_search_node (node, string, start)
     NODE *node;
     char *string;
     long start;
{
  register int i;
  long offset;
  char *target;

  target = savestring (string);
  i = strlen (target);

  /* Try repeatedly searching for this string while removing words from
     the end of it. */
  while (i)
    {
      target[i] = '\0';
      offset = info_search_in_node (target, node, start, (WINDOW *)NULL, 1);

      if (offset != -1)
    break;

      /* Delete the last word from TARGET. */
      for (; i && (!whitespace (target[i]) && (target[i] != ',')); i--);
    }
  free (target);
  return (offset);
}

/* Search for STRING starting in WINDOW at point.  If the string is found
   in this node, set point to that position.  Otherwise, get the file buffer
   associated with WINDOW's node, and search through each node in that file.
   If the search fails, return non-zero, else zero.  Side-effect window
   leaving the node and point where the string was found current. */
static char *last_searched_for_string = (char *)NULL;
static int
info_search_internal (string, window, dir)
     char *string;
     WINDOW *window;
     int dir;
{
  register int i;
  FILE_BUFFER *file_buffer;
  char *initial_nodename;
  long ret, start = 0;

  file_buffer = file_buffer_of_window (window);
  initial_nodename = window->node->nodename;

  if ((info_last_executed_command == info_search) &&
      (last_searched_for_string) &&
      (strcmp (last_searched_for_string, string) == 0))
    {
      ret = info_search_in_node
    (string, window->node, window->point + dir, window, dir);
    }
  else
    {
      ret = info_search_in_node
    (string, window->node, window->point, window, dir);
    }

  maybe_free (last_searched_for_string);
  last_searched_for_string = savestring (string);

  if (ret != -1)
    {
      /* We won! */
      if (!echo_area_is_active && !isearch_is_active)
    window_clear_echo_area ();
      return (0);
    }

  /* The string wasn't found in the current node.  Search through the
     window's file buffer, iff the current node is not "*". */
  if (!file_buffer || (strcmp (initial_nodename, "*") == 0))
    return (-1);

  /* If this file has tags, search through every subfile, starting at
     this node's subfile and node.  Otherwise, search through the
     file's node list. */
  if (file_buffer->tags)
    {
      register int current_tag, number_of_tags;
      char *last_subfile;
      TAG *tag;

      /* Find number of tags and current tag. */
      last_subfile = (char *)NULL;
      for (i = 0; file_buffer->tags[i]; i++)
    if (strcmp (initial_nodename, file_buffer->tags[i]->nodename) == 0)
      {
        current_tag = i;
        last_subfile = file_buffer->tags[i]->filename;
      }

      number_of_tags = i;

      /* If there is no last_subfile, our tag wasn't found. */
      if (!last_subfile)
    return (-1);

      /* Search through subsequent nodes, wrapping around to the top
     of the info file until we find the string or return to this
     window's node and point. */
      while (1)
    {
      NODE *node;

      /* Allow C-g to quit the search, failing it if pressed. */
      return_if_control_g (-1);

      current_tag += dir;

      if (current_tag < 0)
        current_tag = number_of_tags - 1;
      else if (current_tag == number_of_tags)
        current_tag = 0;

      tag = file_buffer->tags[current_tag];

      if (!echo_area_is_active && (last_subfile != tag->filename))
        {
          window_message_in_echo_area
        ("Searching subfile \"%s\"...",
         filename_non_directory (tag->filename));

          last_subfile = tag->filename;
        }

      node = info_get_node (file_buffer->filename, tag->nodename);

      if (!node)
        {
          /* If not doing i-search... */
          if (!echo_area_is_active)
        {
          if (info_recent_file_error)
            info_error (info_recent_file_error);
          else
            info_error (CANT_FILE_NODE,
                filename_non_directory (file_buffer->filename),
                tag->nodename);
        }
          return (-1);
        }

      if (dir < 0)
        start = tag->nodelen;

      ret =
        info_search_in_node (string, node, start, window, dir);

      /* Did we find the string in this node? */
      if (ret != -1)
        {
          /* Yes!  We win. */
          remember_window_and_node (window, node);
          if (!echo_area_is_active)
        window_clear_echo_area ();
          return (0);
        }

      /* No.  Free this node, and make sure that we haven't passed
         our starting point. */
      free (node);

      if (strcmp (initial_nodename, tag->nodename) == 0)
        return (-1);
    }
    }
  return (-1);
}

DECLARE_INFO_COMMAND (info_search, "Read a string and search for it")
{
  char *line, *prompt;
  int result, old_pagetop;
  int direction;

  if (count < 0)
    direction = -1;
  else
    direction = 1;

  /* Read a string from the user, defaulting the search to SEARCH_STRING. */
  if (!search_string)
    {
      search_string = (char *)xmalloc (search_string_size = 100);
      search_string[0] = '\0';
    }

  prompt = (char *)xmalloc (50 + strlen (search_string));

  sprintf (prompt, "%s for string [%s]: ",
       direction < 0 ? "Search backward" : "Search",
       search_string);

  line = info_read_in_echo_area (window, prompt);
  free (prompt);

  if (!line)
    {
      info_abort_key ();
      return;
    }

  if (*line)
    {
      if (strlen (line) + 1 > search_string_size)
    search_string = (char *)
      xrealloc (search_string, (search_string_size += 50 + strlen (line)));

      strcpy (search_string, line);
      search_string_index = strlen (line);
      free (line);
    }

  old_pagetop = active_window->pagetop;
  result = info_search_internal (search_string, active_window, direction);

  if (result != 0 && !info_error_was_printed)
    info_error ("Search failed.");
  else if (old_pagetop != active_window->pagetop)
    {
      int new_pagetop;

      new_pagetop = active_window->pagetop;
      active_window->pagetop = old_pagetop;
      set_window_pagetop (active_window, new_pagetop);
      if (auto_footnotes_p)
    info_get_or_remove_footnotes (active_window);
    }

  /* Perhaps free the unreferenced file buffers that were searched, but
     not retained. */
  info_gc_file_buffers ();
}

/* **************************************************************** */
/*                                    */
/*            Incremental Searching                */
/*                                    */
/* **************************************************************** */

static void incremental_search ();

DECLARE_INFO_COMMAND (isearch_forward,
              "Search interactively for a string as you type it")
{
  incremental_search (window, count, key);
}

DECLARE_INFO_COMMAND (isearch_backward,
              "Search interactively for a string as you type it")
{
  incremental_search (window, -count, key);
}

/* Incrementally search for a string as it is typed. */
/* The last accepted incremental search string. */
static char *last_isearch_accepted = (char *)NULL;

/* The current incremental search string. */
static char *isearch_string = (char *)NULL;
static int isearch_string_index = 0;
static int isearch_string_size = 0;
static unsigned char isearch_terminate_search_key = ESC;

/* Structure defining the current state of an incremental search. */
typedef struct {
  WINDOW_STATE_DECL;    /* The node, pagetop and point. */
  int search_index;    /* Offset of the last char in the search string. */
  int direction;    /* The direction that this search is heading in. */
  int failing;        /* Whether or not this search failed. */
} SEARCH_STATE;

/* Array of search states. */
static SEARCH_STATE **isearch_states = (SEARCH_STATE **)NULL;
static int isearch_states_index = 0;
static int isearch_states_slots = 0;

/* Push the state of this search. */
static void
push_isearch (window, search_index, direction, failing)
     WINDOW *window;
     int search_index, direction, failing;
{
  SEARCH_STATE *state;

  state = (SEARCH_STATE *)xmalloc (sizeof (SEARCH_STATE));
  window_get_state (window, state);
  state->search_index = search_index;
  state->direction = direction;
  state->failing = failing;

  add_pointer_to_array (state, isearch_states_index, isearch_states,
            isearch_states_slots, 20, SEARCH_STATE *);
}

/* Pop the state of this search to WINDOW, SEARCH_INDEX, and DIRECTION. */
static void
pop_isearch (window, search_index, direction, failing)
     WINDOW *window;
     int *search_index, *direction, *failing;
{
  SEARCH_STATE *state;

  if (isearch_states_index)
    {
      isearch_states_index--;
      state = isearch_states[isearch_states_index];
      window_set_state (window, state);
      *search_index = state->search_index;
      *direction = state->direction;
      *failing = state->failing;

      free (state);
      isearch_states[isearch_states_index] = (SEARCH_STATE *)NULL;
    }
}

/* Free the memory used by isearch_states. */
static void
free_isearch_states ()
{
  register int i;

  for (i = 0; i < isearch_states_index; i++)
    {
      free (isearch_states[i]);
      isearch_states[i] = (SEARCH_STATE *)NULL;
    }
  isearch_states_index = 0;
}

/* Display the current search in the echo area. */
static void
show_isearch_prompt (dir, string, failing_p)
     int dir;
     unsigned char *string;
     int failing_p;
{
  register int i;
  char *prefix, *prompt, *p_rep;
  int prompt_len, p_rep_index, p_rep_size;

  if (dir < 0)
    prefix = "I-search backward: ";
  else
    prefix = "I-search: ";

  p_rep_index = p_rep_size = 0;
  p_rep = (char *)NULL;
  for (i = 0; string[i]; i++)
    {
      char *rep;

      switch (string[i])
    {
    case ' ': rep = " "; break;
    case LFD: rep = "\\n"; break;
    case TAB: rep = "\\t"; break;
    default:
      rep = pretty_keyname (string[i]);
    }
      if ((p_rep_index + strlen (rep) + 1) >= p_rep_size)
    p_rep = (char *)xrealloc (p_rep, p_rep_size += 100);

      strcpy (p_rep + p_rep_index, rep);
      p_rep_index += strlen (rep);
    }

  prompt_len = strlen (prefix) + p_rep_index + 20;
  prompt = (char *)xmalloc (prompt_len);
  sprintf (prompt, "%s%s%s", failing_p ? "Failing " : "", prefix,
       p_rep ? p_rep : "");

  window_message_in_echo_area ("%s", prompt);
  maybe_free (p_rep);
  free (prompt);
  display_cursor_at_point (active_window);
}

static void
incremental_search (window, count, ignore)
     WINDOW *window;
     int count;
     unsigned char ignore;
{
  unsigned char key;
  int last_search_result, search_result, dir;
  SEARCH_STATE mystate, orig_state;

  if (count < 0)
    dir = -1;
  else
    dir = 1;

  last_search_result = search_result = 0;

  window_get_state (window, &orig_state);

  isearch_string_index = 0;
  if (!isearch_string_size)
    isearch_string = (char *)xmalloc (isearch_string_size = 50);

  /* Show the search string in the echo area. */
  isearch_string[isearch_string_index] = '\0';
  show_isearch_prompt (dir, isearch_string, search_result);

  isearch_is_active = 1;

  while (isearch_is_active)
    {
      VFunction *func = (VFunction *)NULL;
      int quoted = 0;

      /* If a recent display was interrupted, then do the redisplay now if
     it is convenient. */
      if (!info_any_buffered_input_p () && display_was_interrupted_p)
    {
      display_update_one_window (window);
      display_cursor_at_point (active_window);
    }

      /* Read a character and dispatch on it. */
      key = info_get_input_char ();
      window_get_state (window, &mystate);

      if (key == DEL)
    {
      /* User wants to delete one level of search? */
      if (!isearch_states_index)
        {
          terminal_ring_bell ();
          continue;
        }
      else
        {
          pop_isearch
        (window, &isearch_string_index, &dir, &search_result);
          isearch_string[isearch_string_index] = '\0';
          show_isearch_prompt (dir, isearch_string, search_result);
          goto after_search;
        }
    }
      else if (key == Control ('q'))
    {
      key = info_get_input_char ();
      quoted = 1;
    }

      /* We are about to search again, or quit.  Save the current search. */
      push_isearch (window, isearch_string_index, dir, search_result);

      if (quoted)
    goto insert_and_search;

      if (!Meta_p (key) || (ISO_Latin_p && key < 160))
    {
      func = window->keymap[key].function;

      /* If this key invokes an incremental search, then this means that
         we will either search again in the same direction, search
         again in the reverse direction, or insert the last search
         string that was accepted through incremental searching. */
      if (func == isearch_forward || func == isearch_backward)
        {
          if ((func == isearch_forward && dir > 0) ||
          (func == isearch_backward && dir < 0))
        {
          /* If the user has typed no characters, then insert the
             last successful search into the current search string. */
          if (isearch_string_index == 0)
            {
              /* Of course, there must be something to insert. */
              if (last_isearch_accepted)
            {
              if (strlen (last_isearch_accepted) + 1 >=
                  isearch_string_size)
                isearch_string = (char *)
                  xrealloc (isearch_string,
                    isearch_string_size += 10 +
                    strlen (last_isearch_accepted));
              strcpy (isearch_string, last_isearch_accepted);
              isearch_string_index = strlen (isearch_string);
              goto search_now;
            }
              else
            continue;
            }
          else
            {
              /* Search again in the same direction.  This means start
             from a new place if the last search was successful. */
              if (search_result == 0)
            window->point += dir;
            }
        }
          else
        {
          /* Reverse the direction of the search. */
          dir = -dir;
        }
        }
      else if (isprint (key) || func == (VFunction *)NULL)
        {
        insert_and_search:

          if (isearch_string_index + 2 >= isearch_string_size)
        isearch_string = (char *)xrealloc
          (isearch_string, isearch_string_size += 100);

          isearch_string[isearch_string_index++] = key;
          isearch_string[isearch_string_index] = '\0';
          goto search_now;
        }
      else if (func == info_abort_key)
        {
          /* If C-g pressed, and the search is failing, pop the search
         stack back to the last unfailed search. */
          if (isearch_states_index && (search_result != 0))
        {
          terminal_ring_bell ();
          while (isearch_states_index && (search_result != 0))
            pop_isearch
              (window, &isearch_string_index, &dir, &search_result);
          isearch_string[isearch_string_index] = '\0';
          show_isearch_prompt (dir, isearch_string, search_result);
          continue;
        }
          else
        goto exit_search;
        }
      else
        goto exit_search;
    }
      else
    {
    exit_search:
      /* The character is not printable, or it has a function which is
         non-null.  Exit the search, remembering the search string.  If
         the key is not the same as the isearch_terminate_search_key,
         then push it into pending input. */
      if (isearch_string_index && func != info_abort_key)
        {
          maybe_free (last_isearch_accepted);
          last_isearch_accepted = savestring (isearch_string);
        }

      if (key != isearch_terminate_search_key)
        info_set_pending_input (key);

      if (func == info_abort_key)
        {
          if (isearch_states_index)
        window_set_state (window, &orig_state);
        }

      if (!echo_area_is_active)
        window_clear_echo_area ();

      if (auto_footnotes_p)
        info_get_or_remove_footnotes (active_window);

      isearch_is_active = 0;
      continue;
    }

      /* Search for the contents of isearch_string. */
    search_now:
      show_isearch_prompt (dir, isearch_string, search_result);

      if (search_result == 0)
    {
      /* Check to see if the current search string is right here.  If
         we are looking at it, then don't bother calling the search
         function. */
      if (((dir < 0) &&
           (strnicmp (window->node->contents + window->point,
             isearch_string, isearch_string_index) == 0)) ||
          ((dir > 0) &&
           ((window->point - isearch_string_index) >= 0) &&
           (strnicmp (window->node->contents +
              (window->point - (isearch_string_index - 1)),
              isearch_string, isearch_string_index) == 0)))
        {
          if (dir > 0)
        window->point++;
        }
      else
        search_result = info_search_internal (isearch_string, window, dir);
    }

      /* If this search failed, and we didn't already have a failed search,
     then ring the terminal bell. */
      if (search_result != 0 && last_search_result == 0)
    terminal_ring_bell ();

    after_search:
      show_isearch_prompt (dir, isearch_string, search_result);

      if (search_result == 0)
    {
      if ((mystate.node == window->node) &&
          (mystate.pagetop != window->pagetop))
        {
          int newtop = window->pagetop;
          window->pagetop = mystate.pagetop;
          set_window_pagetop (window, newtop);
        }
      display_update_one_window (window);
      display_cursor_at_point (window);
    }

      last_search_result = search_result;
    }

  /* Free the memory used to remember each search state. */
  free_isearch_states ();

  /* Perhaps GC some file buffers. */
  info_gc_file_buffers ();

  /* After searching, leave the window in the correct state. */
  if (!echo_area_is_active)
    window_clear_echo_area ();
}

/* GC some file buffers.  A file buffer can be gc-ed if there we have
   no nodes in INFO_WINDOWS that reference this file buffer's contents.
   Garbage collecting a file buffer means to free the file buffers
   contents. */
static void
info_gc_file_buffers ()
{
  register int fb_index, iw_index, i;
  register FILE_BUFFER *fb;
  register INFO_WINDOW *iw;

  if (!info_loaded_files)
    return;

  for (fb_index = 0; fb = info_loaded_files[fb_index]; fb_index++)
    {
      int fb_referenced_p = 0;

      /* If already gc-ed, do nothing. */
      if (!fb->contents)
    continue;

      /* If this file had to be uncompressed, check to see if we should
     gc it.  This means that the user-variable "gc-compressed-files"
     is non-zero. */
      if ((fb->flags & N_IsCompressed) && !gc_compressed_files)
    continue;

      /* If this file's contents are not gc-able, move on. */
      if (fb->flags & N_CannotGC)
    continue;

      /* Check each INFO_WINDOW to see if it has any nodes which reference
     this file. */
      for (iw_index = 0; iw = info_windows[iw_index]; iw_index++)
    {
      for (i = 0; iw->nodes && iw->nodes[i]; i++)
        {
          if ((strcmp (fb->fullpath, iw->nodes[i]->filename) == 0) ||
          (strcmp (fb->filename, iw->nodes[i]->filename) == 0))
        {
          fb_referenced_p = 1;
          break;
        }
        }
    }

      /* If this file buffer wasn't referenced, free its contents. */
      if (!fb_referenced_p)
    {
      free (fb->contents);
      fb->contents = (char *)NULL;
    }
    }
}

/* **************************************************************** */
/*                                    */
/*          Traversing and Selecting References            */
/*                                    */
/* **************************************************************** */

/* Move to the next or previous cross reference in this node. */
static void
info_move_to_xref (window, count, key, dir)
     WINDOW *window;
     int count;
     unsigned char key;
     int dir;
{
  long firstmenu, firstxref;
  long nextmenu, nextxref;
  long placement = -1;
  long start = 0;
  NODE *node = window->node;

  if (dir < 0)
    start = node->nodelen;

  /* This search is only allowed to fail if there is no menu or cross
     reference in the current node.  Otherwise, the first menu or xref
     found is moved to. */

  firstmenu = info_search_in_node
    (INFO_MENU_ENTRY_LABEL, node, start, (WINDOW *)NULL, dir);

  /* FIRSTMENU may point directly to the line defining the menu.  Skip that
     and go directly to the first item. */

  if (firstmenu != -1)
    {
      char *text = node->contents + firstmenu;

      if (strncmp (text, INFO_MENU_LABEL, strlen (INFO_MENU_LABEL)) == 0)
    firstmenu = info_search_in_node
      (INFO_MENU_ENTRY_LABEL, node, firstmenu + dir, (WINDOW *)NULL, dir);
    }

  firstxref =
    info_search_in_node (INFO_XREF_LABEL, node, start, (WINDOW *)NULL, dir);

  if (firstmenu == -1 && firstxref == -1)
    {
      info_error ("No cross references in this node.");
      return;
    }

  /* There is at least one cross reference or menu entry in this node.
     Try hard to find the next available one. */

  nextmenu = info_search_in_node
    (INFO_MENU_ENTRY_LABEL, node, window->point + dir, (WINDOW *)NULL, dir);

  nextxref = info_search_in_node
    (INFO_XREF_LABEL, node, window->point + dir, (WINDOW *)NULL, dir);

  /* Ignore "Menu:" as a menu item. */
  if (nextmenu != -1)
    {
      char *text = node->contents + nextmenu;

      if (strncmp (text, INFO_MENU_LABEL, strlen (INFO_MENU_LABEL)) == 0)
    nextmenu = info_search_in_node
      (INFO_MENU_ENTRY_LABEL, node, nextmenu + dir, (WINDOW *)NULL, dir);
    }

  /* If there is both a next menu entry, and a next xref entry, choose the
     one which occurs first.  Otherwise, select the one which actually
     appears in this node following point. */
  if (nextmenu != -1 && nextxref != -1)
    {
      if (((dir == 1) && (nextmenu < nextxref)) ||
      ((dir == -1) && (nextmenu > nextxref)))
    placement = nextmenu + 1;
      else
    placement = nextxref;
    }
  else if (nextmenu != -1)
    placement = nextmenu + 1;
  else if (nextxref != -1)
    placement = nextxref;

  /* If there was neither a menu or xref entry appearing in this node after
     point, choose the first menu or xref entry appearing in this node. */
  if (placement == -1)
    {
      if (firstmenu != -1 && firstxref != -1)
    {
      if (((dir == 1) && (firstmenu < firstxref)) ||
          ((dir == -1) && (firstmenu > firstxref)))
        placement = firstmenu + 1;
      else
        placement = firstxref;
    }
      else if (firstmenu != -1)
    placement = firstmenu + 1;
      else
    placement = firstxref;
    }
  window->point = placement;
  window_adjust_pagetop (window);
  window->flags |= W_UpdateWindow;
}

DECLARE_INFO_COMMAND (info_move_to_prev_xref,
              "Move to the previous cross reference")
{
  if (count < 0)
    info_move_to_prev_xref (window, -count, key);
  else
    info_move_to_xref (window, count, key, -1);
}

DECLARE_INFO_COMMAND (info_move_to_next_xref,
              "Move to the next cross reference")
{
  if (count < 0)
    info_move_to_next_xref (window, -count, key);
  else
    info_move_to_xref (window, count, key, 1);
}

/* Select the menu item or reference that appears on this line. */
DECLARE_INFO_COMMAND (info_select_reference_this_line,
              "Select reference or menu item appearing on this line")
{
  char *line;
  NODE *orig;

  line = window->line_starts[window_line_of_point (window)];
  orig = window->node;

  /* If this line contains a menu item, select that one. */
  if (strncmp ("* ", line, 2) == 0)
    info_menu_or_ref_item (window, count, key, info_menu_of_node, 0);
  else
    info_menu_or_ref_item (window, count, key, info_xrefs_of_node, 0);
}

/* **************************************************************** */
/*                                    */
/*            Miscellaneous Info Commands                */
/*                                    */
/* **************************************************************** */

/* What to do when C-g is pressed in a window. */
DECLARE_INFO_COMMAND (info_abort_key, "Cancel current operation")
{
  /* If error printing doesn't oridinarily ring the bell, do it now,
     since C-g always rings the bell.  Otherwise, let the error printer
     do it. */
  if (!info_error_rings_bell_p)
    terminal_ring_bell ();
  info_error ("Quit");

  info_initialize_numeric_arg ();
  info_clear_pending_input ();
  info_last_executed_command = (VFunction *)NULL;
}

/* Move the cursor to the desired line of the window. */
DECLARE_INFO_COMMAND (info_move_to_window_line,
   "Move to the cursor to a specific line of the window")
{
  int line;

  /* With no numeric argument of any kind, default to the center line. */
  if (!info_explicit_arg && count == 1)
    line = (window->height / 2) + window->pagetop;
  else
    {
      if (count < 0)
    line = (window->height + count) + window->pagetop;
      else
    line = window->pagetop + count;
    }

  /* If the line doesn't appear in this window, make it do so. */
  if ((line - window->pagetop) >= window->height)
    line = window->pagetop + (window->height - 1);

  /* If the line is too small, make it fit. */
  if (line < window->pagetop)
    line = window->pagetop;

  /* If the selected line is past the bottom of the node, force it back. */
  if (line >= window->line_count)
    line = window->line_count - 1;

  window->point = (window->line_starts[line] - window->node->contents);
}

/* Clear the screen and redraw its contents.  Given a numeric argument,
   move the line the cursor is on to the COUNT'th line of the window. */
DECLARE_INFO_COMMAND (info_redraw_display, "Redraw the display")
{
  if ((!info_explicit_arg && count == 1) || echo_area_is_active)
    {
      terminal_clear_screen ();
      display_clear_display (the_display);
      window_mark_chain (windows, W_UpdateWindow);
      display_update_display (windows);
    }
  else
    {
      int desired_line, point_line;
      int new_pagetop;

      point_line = window_line_of_point (window) - window->pagetop;

      if (count < 0)
    desired_line = window->height + count;
      else
    desired_line = count;

      if (desired_line < 0)
    desired_line = 0;

      if (desired_line >= window->height)
    desired_line = window->height - 1;

      if (desired_line == point_line)
    return;

      new_pagetop = window->pagetop + (point_line - desired_line);

      set_window_pagetop (window, new_pagetop);
    }
}
/* This command does nothing.  It is the fact that a key is bound to it
   that has meaning.  See the code at the top of info_session (). */
DECLARE_INFO_COMMAND (info_quit, "Quit using Info")
{}


/* **************************************************************** */
/*                                    */
/*         Reading Keys and Dispatching on Them            */
/*                                    */
/* **************************************************************** */

/* Declaration only.  Special cased in info_dispatch_on_key (). */
DECLARE_INFO_COMMAND (info_do_lowercase_version, "")
{}

static void
dispatch_error (keyseq)
     char *keyseq;
{
  char *rep;

  rep = pretty_keyseq (keyseq);

  if (!echo_area_is_active)
    info_error ("Unknown command (%s).", rep);
  else
    {
      char *temp;

      temp = (char *)xmalloc (1 + strlen (rep) + strlen ("\"\" is invalid"));

      sprintf (temp, "\"%s\" is invalid", rep);
      terminal_ring_bell ();
      inform_in_echo_area (temp);
      free (temp);
    }
}

/* Keeping track of key sequences. */
static char *info_keyseq = (char *)NULL;
static char keyseq_rep[100];
static int info_keyseq_index = 0;
static int info_keyseq_size = 0;
static int info_keyseq_displayed_p = 0;

/* Initialize the length of the current key sequence. */
void
initialize_keyseq ()
{
  info_keyseq_index = 0;
  info_keyseq_displayed_p = 0;
}

/* Add CHARACTER to the current key sequence. */
void
add_char_to_keyseq (character)
     char character;
{
  if (info_keyseq_index + 2 >= info_keyseq_size)
    info_keyseq = (char *)xrealloc (info_keyseq, info_keyseq_size += 10);

  info_keyseq[info_keyseq_index++] = character;
  info_keyseq[info_keyseq_index] = '\0';
}

/* Return the pretty printable string which represents KEYSEQ. */
char *
pretty_keyseq (keyseq)
     char *keyseq;
{
  register int i;

  keyseq_rep[0] = '\0';

  for (i = 0; keyseq[i]; i++)
    {
      sprintf (keyseq_rep + strlen (keyseq_rep), "%s%s",
           strlen (keyseq_rep) ? " " : "",
           pretty_keyname (keyseq[i]));
    }

  return (keyseq_rep);
}

/* Display the current value of info_keyseq.  If argument EXPECTING is
   non-zero, input is expected to be read after the key sequence is
   displayed, so add an additional prompting character to the sequence. */
void
display_info_keyseq (expecting_future_input)
     int expecting_future_input;
{
  char *rep;

  rep = pretty_keyseq (info_keyseq);
  if (expecting_future_input)
    strcat (rep, "-");

  if (echo_area_is_active)
    inform_in_echo_area (rep);
  else
    {
      window_message_in_echo_area (rep);
      display_cursor_at_point (active_window);
    }
  info_keyseq_displayed_p = 1;
}

/* Called by interactive commands to read a keystroke. */
unsigned char
info_get_another_input_char ()
{
  int ready = 0;

  /* If there isn't any input currently available, then wait a
     moment looking for input.  If we don't get it fast enough,
     prompt a little bit with the current key sequence. */
  if (!info_keyseq_displayed_p &&
      !info_any_buffered_input_p () &&
      !info_input_pending_p ())
    {
#if defined (FD_SET)
      struct timeval timer;
      fd_set readfds;

      FD_ZERO (&readfds);
      FD_SET (fileno (info_input_stream), &readfds);
      timer.tv_sec = 1;
      timer.tv_usec = 750;
      ready = select (1, &readfds, (fd_set *)NULL, (fd_set *)NULL, &timer);
#endif /* FD_SET */
    }

  if (!ready)
    display_info_keyseq (1);

  return (info_get_input_char ());
}

/* Do the command associated with KEY in MAP.  If the associated command is
   really a keymap, then read another key, and dispatch into that map. */
void
info_dispatch_on_key (key, map)
     unsigned char key;
     Keymap map;
{
  if (Meta_p (key) && (!ISO_Latin_p || map[key].function != ea_insert))
    {
      if (map[ESC].type == ISKMAP)
    {
      map = (Keymap)map[ESC].function;
      add_char_to_keyseq (ESC);
      key = UnMeta (key);
      info_dispatch_on_key (key, map);
    }
      else
    {
      dispatch_error (info_keyseq);
    }
      return;
    }

  switch (map[key].type)
    {
    case ISFUNC:
      {
    VFunction *func;

    func = map[key].function;
    if (func != (VFunction *)NULL)
      {
        /* Special case info_do_lowercase_version (). */
        if (func == info_do_lowercase_version)
          {
        info_dispatch_on_key (tolower (key), map);
        return;
          }

        add_char_to_keyseq (key);

        if (info_keyseq_displayed_p)
          display_info_keyseq (0);

        {
          WINDOW *where;

          where = active_window;
          (*map[key].function)
        (active_window, info_numeric_arg * info_numeric_arg_sign, key);

          /* If we have input pending, then the last command was a prefix
         command.  Don't change the value of the last function vars.
         Otherwise, remember the last command executed in the var
         appropriate to the window in which it was executed. */
          if (!info_input_pending_p ())
        {
          if (where == the_echo_area)
            ea_last_executed_command = map[key].function;
          else
            info_last_executed_command = map[key].function;
        }
        }
      }
    else
      {
        add_char_to_keyseq (key);
        dispatch_error (info_keyseq);
        return;
      }
      }
      break;

    case ISKMAP:
      add_char_to_keyseq (key);
      if (map[key].function != (VFunction *)NULL)
    {
      unsigned char newkey;

      newkey = info_get_another_input_char ();
      info_dispatch_on_key (newkey, (Keymap)map[key].function);
    }
      else
    {
      dispatch_error (info_keyseq);
      return;
    }
      break;
    }
}

/* **************************************************************** */
/*                                    */
/*            Numeric Arguments                */
/*                                    */
/* **************************************************************** */

/* Handle C-u style numeric args, as well as M--, and M-digits. */

/* Non-zero means that an explicit argument has been passed to this
   command, as in C-u C-v. */
int info_explicit_arg = 0;

/* The sign of the numeric argument. */
int info_numeric_arg_sign = 1;

/* The value of the argument itself. */
int info_numeric_arg = 1;

/* Add the current digit to the argument in progress. */
DECLARE_INFO_COMMAND (info_add_digit_to_numeric_arg,
              "Add this digit to the current numeric argument")
{
  info_numeric_arg_digit_loop (window, 0, key);
}

/* C-u, universal argument.  Multiply the current argument by 4.
   Read a key.  If the key has nothing to do with arguments, then
   dispatch on it.  If the key is the abort character then abort. */
DECLARE_INFO_COMMAND (info_universal_argument,
              "Start (or multiply by 4) the current numeric argument")
{
  info_numeric_arg *= 4;
  info_numeric_arg_digit_loop (window, 0, 0);
}

/* Create a default argument. */
void
info_initialize_numeric_arg ()
{
  info_numeric_arg = info_numeric_arg_sign = 1;
  info_explicit_arg = 0;
}

DECLARE_INFO_COMMAND (info_numeric_arg_digit_loop, "")
{
  unsigned char pure_key;
  Keymap keymap = window->keymap;

  while (1)
    {
      if (key)
    pure_key = key;
      else
    {
      if (display_was_interrupted_p && !info_any_buffered_input_p ())
        display_update_display (windows);

      if (active_window != the_echo_area)
        display_cursor_at_point (active_window);

      pure_key = key = info_get_another_input_char ();

      if (Meta_p (key))
        add_char_to_keyseq (ESC);

      add_char_to_keyseq (UnMeta (key));
    }

      if (Meta_p (key))
    key = UnMeta (key);

      if (keymap[key].type == ISFUNC &&
      keymap[key].function == info_universal_argument)
    {
      info_numeric_arg *= 4;
      key = 0;
      continue;
    }

      if (isdigit (key))
    {
      if (info_explicit_arg)
        info_numeric_arg = (info_numeric_arg * 10) + (key - '0');
      else
        info_numeric_arg = (key - '0');
      info_explicit_arg = 1;
    }
      else
    {
      if (key == '-' && !info_explicit_arg)
        {
          info_numeric_arg_sign = -1;
          info_numeric_arg = 1;
        }
      else
        {
          info_keyseq_index--;
          info_dispatch_on_key (pure_key, keymap);
          return;
        }
    }
      key = 0;
    }
}

/* **************************************************************** */
/*                                    */
/*            Input Character Buffering               */
/*                                    */
/* **************************************************************** */

/* Character waiting to be read next. */
static int pending_input_character = 0;

/* How to make there be no pending input. */
static void
info_clear_pending_input ()
{
  pending_input_character = 0;
}

/* How to set the pending input character. */
static void
info_set_pending_input (key)
     unsigned char key;
{
  pending_input_character = key;
}

/* How to see if there is any pending input. */
unsigned char
info_input_pending_p ()
{
  return (pending_input_character);
}

/* Largest number of characters that we can read in advance. */
#define MAX_INFO_INPUT_BUFFERING 512

static int pop_index = 0, push_index = 0;
static unsigned char info_input_buffer[MAX_INFO_INPUT_BUFFERING];

/* Add KEY to the buffer of characters to be read. */
static void
info_push_typeahead (key)
     unsigned char key;
{
  /* Flush all pending input in the case of C-g pressed. */
  if (key == Control ('g'))
    {
      push_index = pop_index;
      info_set_pending_input (Control ('g'));
    }
  else
    {
      info_input_buffer[push_index++] = key;
      if (push_index >= sizeof (info_input_buffer))
    push_index = 0;
    }
}

/* Return the amount of space available in INFO_INPUT_BUFFER for new chars. */
static int
info_input_buffer_space_available ()
{
  if (pop_index > push_index)
    return (pop_index - push_index);
  else
    return (sizeof (info_input_buffer - (push_index - pop_index)));
}

/* Get a key from the buffer of characters to be read.
   Return the key in KEY.
   Result is non-zero if there was a key, or 0 if there wasn't. */
static int
info_get_key_from_typeahead (key)
     unsigned char *key;
{
  if (push_index == pop_index)
    return (0);

  *key = info_input_buffer[pop_index++];

  if (pop_index >= sizeof (info_input_buffer))
    pop_index = 0;

  return (1);
}

int
info_any_buffered_input_p ()
{
  info_gather_typeahead ();
  return (push_index != pop_index);
}

/* Push KEY into the *front* of the input buffer.  Returns non-zero if
   successful, zero if there is no space left in the buffer. */
static int
info_replace_key_to_typeahead (key)
     unsigned char key;
{
  if (info_input_buffer_space_available ())
    {
      pop_index--;
      if (pop_index < 0)
    pop_index = sizeof (info_input_buffer) - 1;
      info_input_buffer[pop_index] = key;
      return (1);
    }
  return (0);
}

/* If characters are available to be read, then read them and stuff them into
   info_input_buffer.  Otherwise, do nothing. */
void
info_gather_typeahead ()
{
  int tty, space_avail;
  long chars_avail;
  unsigned char input[MAX_INFO_INPUT_BUFFERING];

  tty = fileno (info_input_stream);
  chars_avail = 0;

  space_avail = info_input_buffer_space_available ();

  /* If we can just find out how many characters there are to read, do so. */
#if defined (FIONREAD)
  {
    ioctl (tty, FIONREAD, &chars_avail);

    if (chars_avail > space_avail)
      chars_avail = space_avail;

    if (chars_avail)
      read (tty, &input[0], chars_avail);
  }
#else /* !FIONREAD */
#  if defined (O_NDELAY)
  {
    int flags;

    flags = fcntl (tty, F_GETFL, 0);

    fcntl (tty, F_SETFL, (flags | O_NDELAY));
      chars_avail = read (tty, &input[0], space_avail);
    fcntl (tty, F_SETFL, flags);

    if (chars_avail == -1)
      chars_avail = 0;
  }
#  endif /* O_NDELAY */
#endif /* !FIONREAD */

  /* Store the input characters just read into our input buffer. */
  {
    register int i;

    for (i = 0; i < chars_avail; i++)
      info_push_typeahead (input[i]);
  }
}

/* How to read a single character. */
unsigned char
info_get_input_char ()
{
  unsigned char keystroke;

  info_gather_typeahead ();

  if (pending_input_character)
    {
      keystroke = pending_input_character;
      pending_input_character = 0;
    }
  else if (info_get_key_from_typeahead (&keystroke) == 0)
    {
      int rawkey;

      rawkey = getc (info_input_stream);
      keystroke = rawkey;

      if (rawkey == EOF)
    {
      if (info_input_stream != stdin)
        {
          fclose (info_input_stream);
          info_input_stream = stdin;
          display_inhibited = 0;
          display_update_display (windows);
          display_cursor_at_point (active_window);
          rawkey = getc (info_input_stream);
          keystroke = rawkey;
        }

      if (rawkey == EOF)
        {
          terminal_unprep_terminal ();
          close_dribble_file ();
          exit (0);
        }
    }
    }

  if (info_dribble_file)
    dribble (keystroke);

  return (keystroke);
}