buffer.c

/* Buffer manipulation primitives for GNU Emacs.
   Copyright (C) 1985, 1986, 1987, 1988, 1989, 1993, 1994,
                 1995, 1997, 1998, 1999, 2000, 2001, 2002,
                 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GNU Emacs 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 GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

#include <config.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <errno.h>
#include <stdio.h>

#ifndef USE_CRT_DLL
extern int errno;
#endif


#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "lisp.h"
#include "intervals.h"
#include "window.h"
#include "commands.h"
#include "buffer.h"
#include "charset.h"
#include "region-cache.h"
#include "indent.h"
#include "blockinput.h"
#include "keyboard.h"
#include "keymap.h"
#include "frame.h"

struct buffer *current_buffer;		/* the current buffer */

/* First buffer in chain of all buffers (in reverse order of creation).
   Threaded through ->next.  */

struct buffer *all_buffers;

/* This structure holds the default values of the buffer-local variables
   defined with DEFVAR_PER_BUFFER, that have special slots in each buffer.
   The default value occupies the same slot in this structure
   as an individual buffer's value occupies in that buffer.
   Setting the default value also goes through the alist of buffers
   and stores into each buffer that does not say it has a local value.  */

DECL_ALIGN (struct buffer, buffer_defaults);

/* A Lisp_Object pointer to the above, used for staticpro */

static Lisp_Object Vbuffer_defaults;

/* This structure marks which slots in a buffer have corresponding
   default values in buffer_defaults.
   Each such slot has a nonzero value in this structure.
   The value has only one nonzero bit.

   When a buffer has its own local value for a slot,
   the entry for that slot (found in the same slot in this structure)
   is turned on in the buffer's local_flags array.

   If a slot in this structure is -1, then even though there may
   be a DEFVAR_PER_BUFFER for the slot, there is no default value for it;
   and the corresponding slot in buffer_defaults is not used.

   If a slot is -2, then there is no DEFVAR_PER_BUFFER for it,
   but there is a default value which is copied into each buffer.

   If a slot in this structure corresponding to a DEFVAR_PER_BUFFER is
   zero, that is a bug */

struct buffer buffer_local_flags;

/* This structure holds the names of symbols whose values may be
   buffer-local.  It is indexed and accessed in the same way as the above. */

DECL_ALIGN (struct buffer, buffer_local_symbols);

/* A Lisp_Object pointer to the above, used for staticpro */
static Lisp_Object Vbuffer_local_symbols;

/* Flags indicating which built-in buffer-local variables
   are permanent locals.  */
static char buffer_permanent_local_flags[MAX_PER_BUFFER_VARS];

/* Number of per-buffer variables used.  */

int last_per_buffer_idx;

Lisp_Object Fset_buffer ();
void set_buffer_internal ();
void set_buffer_internal_1 ();
static void call_overlay_mod_hooks ();
static void swap_out_buffer_local_variables ();
static void reset_buffer_local_variables ();

/* Alist of all buffer names vs the buffers. */
/* This used to be a variable, but is no longer,
 to prevent lossage due to user rplac'ing this alist or its elements.  */
Lisp_Object Vbuffer_alist;

/* Functions to call before and after each text change. */
Lisp_Object Vbefore_change_functions;
Lisp_Object Vafter_change_functions;

Lisp_Object Vtransient_mark_mode;

/* t means ignore all read-only text properties.
   A list means ignore such a property if its value is a member of the list.
   Any non-nil value means ignore buffer-read-only.  */
Lisp_Object Vinhibit_read_only;

/* List of functions to call that can query about killing a buffer.
   If any of these functions returns nil, we don't kill it.  */
Lisp_Object Vkill_buffer_query_functions;
Lisp_Object Qkill_buffer_query_functions;

/* Hook run before changing a major mode.  */
Lisp_Object Vchange_major_mode_hook, Qchange_major_mode_hook;

/* List of functions to call before changing an unmodified buffer.  */
Lisp_Object Vfirst_change_hook;

Lisp_Object Qfirst_change_hook;
Lisp_Object Qbefore_change_functions;
Lisp_Object Qafter_change_functions;
Lisp_Object Qucs_set_table_for_input;

/* If nonzero, all modification hooks are suppressed.  */
int inhibit_modification_hooks;

Lisp_Object Qfundamental_mode, Qmode_class, Qpermanent_local;

Lisp_Object Qprotected_field;

Lisp_Object QSFundamental;	/* A string "Fundamental" */

Lisp_Object Qkill_buffer_hook;

Lisp_Object Qget_file_buffer;

Lisp_Object Qoverlayp;

Lisp_Object Qpriority, Qwindow, Qevaporate, Qbefore_string, Qafter_string;

Lisp_Object Qmodification_hooks;
Lisp_Object Qinsert_in_front_hooks;
Lisp_Object Qinsert_behind_hooks;

static void alloc_buffer_text P_ ((struct buffer *, size_t));
static void free_buffer_text P_ ((struct buffer *b));
static struct Lisp_Overlay * copy_overlays P_ ((struct buffer *, struct Lisp_Overlay *));
static void modify_overlay P_ ((struct buffer *, EMACS_INT, EMACS_INT));
static Lisp_Object buffer_lisp_local_variables P_ ((struct buffer *));


/* For debugging; temporary.  See set_buffer_internal.  */
/* Lisp_Object Qlisp_mode, Vcheck_symbol; */

void
nsberror (spec)
     Lisp_Object spec;
{
  if (STRINGP (spec))
    error ("No buffer named %s", SDATA (spec));
  error ("Invalid buffer argument");
}

DEFUN ("buffer-live-p", Fbuffer_live_p, Sbuffer_live_p, 1, 1, 0,
       doc: /* Return non-nil if OBJECT is a buffer which has not been killed.
Value is nil if OBJECT is not a buffer or if it has been killed.  */)
     (object)
     Lisp_Object object;
{
  return ((BUFFERP (object) && ! NILP (XBUFFER (object)->name))
	  ? Qt : Qnil);
}

DEFUN ("buffer-list", Fbuffer_list, Sbuffer_list, 0, 1, 0,
       doc: /* Return a list of all existing live buffers.
If the optional arg FRAME is a frame, we return the buffer list
in the proper order for that frame: the buffers in FRAME's `buffer-list'
frame parameter come first, followed by the rest of the buffers.  */)
     (frame)
     Lisp_Object frame;
{
  Lisp_Object general;
  general = Fmapcar (Qcdr, Vbuffer_alist);

  if (FRAMEP (frame))
    {
      Lisp_Object framelist, prevlist, tail;
      Lisp_Object args[3];

      CHECK_FRAME (frame);

      framelist = Fcopy_sequence (XFRAME (frame)->buffer_list);
      prevlist = Fnreverse (Fcopy_sequence (XFRAME (frame)->buried_buffer_list));

      /* Remove from GENERAL any buffer that duplicates one in
         FRAMELIST or PREVLIST.  */
      tail = framelist;
      while (CONSP (tail))
	{
	  general = Fdelq (XCAR (tail), general);
	  tail = XCDR (tail);
	}
      tail = prevlist;
      while (CONSP (tail))
	{
	  general = Fdelq (XCAR (tail), general);
	  tail = XCDR (tail);
	}

      args[0] = framelist;
      args[1] = general;
      args[2] = prevlist;
      return Fnconc (3, args);
    }

  return general;
}

/* Like Fassoc, but use Fstring_equal to compare
   (which ignores text properties),
   and don't ever QUIT.  */

static Lisp_Object
assoc_ignore_text_properties (key, list)
     register Lisp_Object key;
     Lisp_Object list;
{
  register Lisp_Object tail;
  for (tail = list; CONSP (tail); tail = XCDR (tail))
    {
      register Lisp_Object elt, tem;
      elt = XCAR (tail);
      tem = Fstring_equal (Fcar (elt), key);
      if (!NILP (tem))
	return elt;
    }
  return Qnil;
}

DEFUN ("get-buffer", Fget_buffer, Sget_buffer, 1, 1, 0,
       doc: /* Return the buffer named NAME (a string).
If there is no live buffer named NAME, return nil.
NAME may also be a buffer; if so, the value is that buffer.  */)
     (name)
     register Lisp_Object name;
{
  if (BUFFERP (name))
    return name;
  CHECK_STRING (name);

  return Fcdr (assoc_ignore_text_properties (name, Vbuffer_alist));
}

DEFUN ("get-file-buffer", Fget_file_buffer, Sget_file_buffer, 1, 1, 0,
       doc: /* Return the buffer visiting file FILENAME (a string).
The buffer's `buffer-file-name' must match exactly the expansion of FILENAME.
If there is no such live buffer, return nil.
See also `find-buffer-visiting'.  */)
     (filename)
     register Lisp_Object filename;
{
  register Lisp_Object tail, buf, tem;
  Lisp_Object handler;

  CHECK_STRING (filename);
  filename = Fexpand_file_name (filename, Qnil);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (filename, Qget_file_buffer);
  if (!NILP (handler))
    return call2 (handler, Qget_file_buffer, filename);

  for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail))
    {
      buf = Fcdr (XCAR (tail));
      if (!BUFFERP (buf)) continue;
      if (!STRINGP (XBUFFER (buf)->filename)) continue;
      tem = Fstring_equal (XBUFFER (buf)->filename, filename);
      if (!NILP (tem))
	return buf;
    }
  return Qnil;
}

Lisp_Object
get_truename_buffer (filename)
     register Lisp_Object filename;
{
  register Lisp_Object tail, buf, tem;

  for (tail = Vbuffer_alist; CONSP (tail); tail = XCDR (tail))
    {
      buf = Fcdr (XCAR (tail));
      if (!BUFFERP (buf)) continue;
      if (!STRINGP (XBUFFER (buf)->file_truename)) continue;
      tem = Fstring_equal (XBUFFER (buf)->file_truename, filename);
      if (!NILP (tem))
	return buf;
    }
  return Qnil;
}

/* Incremented for each buffer created, to assign the buffer number. */
int buffer_count;

DEFUN ("get-buffer-create", Fget_buffer_create, Sget_buffer_create, 1, 1, 0,
       doc: /* Return the buffer named NAME, or create such a buffer and return it.
A new buffer is created if there is no live buffer named NAME.
If NAME starts with a space, the new buffer does not keep undo information.
If NAME is a buffer instead of a string, then it is the value returned.
The value is never nil.  */)
     (name)
     register Lisp_Object name;
{
  register Lisp_Object buf;
  register struct buffer *b;

  buf = Fget_buffer (name);
  if (!NILP (buf))
    return buf;

  if (SCHARS (name) == 0)
    error ("Empty string for buffer name is not allowed");

  b = allocate_buffer ();

  /* An ordinary buffer uses its own struct buffer_text.  */
  b->text = &b->own_text;
  b->base_buffer = 0;

  BUF_GAP_SIZE (b) = 20;
  BLOCK_INPUT;
  /* We allocate extra 1-byte at the tail and keep it always '\0' for
     anchoring a search.  */
  alloc_buffer_text (b, BUF_GAP_SIZE (b) + 1);
  UNBLOCK_INPUT;
  if (! BUF_BEG_ADDR (b))
    buffer_memory_full ();

  BUF_PT (b) = BEG;
  BUF_GPT (b) = BEG;
  BUF_BEGV (b) = BEG;
  BUF_ZV (b) = BEG;
  BUF_Z (b) = BEG;
  BUF_PT_BYTE (b) = BEG_BYTE;
  BUF_GPT_BYTE (b) = BEG_BYTE;
  BUF_BEGV_BYTE (b) = BEG_BYTE;
  BUF_ZV_BYTE (b) = BEG_BYTE;
  BUF_Z_BYTE (b) = BEG_BYTE;
  BUF_MODIFF (b) = 1;
  BUF_CHARS_MODIFF (b) = 1;
  BUF_OVERLAY_MODIFF (b) = 1;
  BUF_SAVE_MODIFF (b) = 1;
  BUF_INTERVALS (b) = 0;
  BUF_UNCHANGED_MODIFIED (b) = 1;
  BUF_OVERLAY_UNCHANGED_MODIFIED (b) = 1;
  BUF_END_UNCHANGED (b) = 0;
  BUF_BEG_UNCHANGED (b) = 0;
  *(BUF_GPT_ADDR (b)) = *(BUF_Z_ADDR (b)) = 0; /* Put an anchor '\0'.  */

  b->newline_cache = 0;
  b->width_run_cache = 0;
  b->width_table = Qnil;
  b->prevent_redisplay_optimizations_p = 1;

  /* Put this on the chain of all buffers including killed ones.  */
  b->next = all_buffers;
  all_buffers = b;

  /* An ordinary buffer normally doesn't need markers
     to handle BEGV and ZV.  */
  b->pt_marker = Qnil;
  b->begv_marker = Qnil;
  b->zv_marker = Qnil;

  name = Fcopy_sequence (name);
  STRING_SET_INTERVALS (name, NULL_INTERVAL);
  b->name = name;

  b->undo_list = (SREF (name, 0) != ' ') ? Qnil : Qt;

  reset_buffer (b);
  reset_buffer_local_variables (b, 1);

  b->mark = Fmake_marker ();
  BUF_MARKERS (b) = NULL;
  b->name = name;

  /* Put this in the alist of all live buffers.  */
  XSETBUFFER (buf, b);
  Vbuffer_alist = nconc2 (Vbuffer_alist, Fcons (Fcons (name, buf), Qnil));

  /* An error in calling the function here (should someone redefine it)
     can lead to infinite regress until you run out of stack.  rms
     says that's not worth protecting against.  */
  if (!NILP (Ffboundp (Qucs_set_table_for_input)))
    /* buf is on buffer-alist, so no gcpro.  */
    call1 (Qucs_set_table_for_input, buf);

  return buf;
}


/* Return a list of overlays which is a copy of the overlay list
   LIST, but for buffer B.  */

static struct Lisp_Overlay *
copy_overlays (b, list)
     struct buffer *b;
     struct Lisp_Overlay *list;
{
  Lisp_Object buffer;
  struct Lisp_Overlay *result = NULL, *tail = NULL;

  XSETBUFFER (buffer, b);

  for (; list; list = list->next)
    {
      Lisp_Object overlay, start, end, old_overlay;
      EMACS_INT charpos;

      XSETMISC (old_overlay, list);
      charpos = marker_position (OVERLAY_START (old_overlay));
      start = Fmake_marker ();
      Fset_marker (start, make_number (charpos), buffer);
      XMARKER (start)->insertion_type
	= XMARKER (OVERLAY_START (old_overlay))->insertion_type;

      charpos = marker_position (OVERLAY_END (old_overlay));
      end = Fmake_marker ();
      Fset_marker (end, make_number (charpos), buffer);
      XMARKER (end)->insertion_type
	= XMARKER (OVERLAY_END (old_overlay))->insertion_type;

      overlay = allocate_misc ();
      XMISCTYPE (overlay) = Lisp_Misc_Overlay;
      OVERLAY_START (overlay) = start;
      OVERLAY_END (overlay) = end;
      OVERLAY_PLIST (overlay) = Fcopy_sequence (OVERLAY_PLIST (old_overlay));
      XOVERLAY (overlay)->next = NULL;

      if (tail)
	tail = tail->next = XOVERLAY (overlay);
      else
	result = tail = XOVERLAY (overlay);
    }

  return result;
}


/* Clone per-buffer values of buffer FROM.

   Buffer TO gets the same per-buffer values as FROM, with the
   following exceptions: (1) TO's name is left untouched, (2) markers
   are copied and made to refer to TO, and (3) overlay lists are
   copied.  */

static void
clone_per_buffer_values (from, to)
     struct buffer *from, *to;
{
  Lisp_Object to_buffer;
  int offset;

  XSETBUFFER (to_buffer, to);

  for (offset = PER_BUFFER_VAR_OFFSET (name) + sizeof (Lisp_Object);
       offset < sizeof *to;
       offset += sizeof (Lisp_Object))
    {
      Lisp_Object obj;

      obj = PER_BUFFER_VALUE (from, offset);
      if (MARKERP (obj))
	{
	  struct Lisp_Marker *m = XMARKER (obj);
	  obj = Fmake_marker ();
	  XMARKER (obj)->insertion_type = m->insertion_type;
	  set_marker_both (obj, to_buffer, m->charpos, m->bytepos);
	}

      PER_BUFFER_VALUE (to, offset) = obj;
    }

  bcopy (from->local_flags, to->local_flags, sizeof to->local_flags);

  to->overlays_before = copy_overlays (to, from->overlays_before);
  to->overlays_after = copy_overlays (to, from->overlays_after);

  /* Get (a copy of) the alist of Lisp-level local variables of FROM
     and install that in TO.  */
  to->local_var_alist = buffer_lisp_local_variables (from);
}

DEFUN ("make-indirect-buffer", Fmake_indirect_buffer, Smake_indirect_buffer,
       2, 3,
       "bMake indirect buffer (to buffer): \nBName of indirect buffer: ",
       doc: /* Create and return an indirect buffer for buffer BASE-BUFFER, named NAME.
BASE-BUFFER should be a live buffer, or the name of an existing buffer.
NAME should be a string which is not the name of an existing buffer.
Optional argument CLONE non-nil means preserve BASE-BUFFER's state,
such as major and minor modes, in the indirect buffer.
CLONE nil means the indirect buffer's state is reset to default values.  */)
     (base_buffer, name, clone)
     Lisp_Object base_buffer, name, clone;
{
  Lisp_Object buf, tem;
  struct buffer *b;

  CHECK_STRING (name);
  buf = Fget_buffer (name);
  if (!NILP (buf))
    error ("Buffer name `%s' is in use", SDATA (name));

  tem = base_buffer;
  base_buffer = Fget_buffer (base_buffer);
  if (NILP (base_buffer))
    error ("No such buffer: `%s'", SDATA (tem));
  if (NILP (XBUFFER (base_buffer)->name))
    error ("Base buffer has been killed");

  if (SCHARS (name) == 0)
    error ("Empty string for buffer name is not allowed");

  b = allocate_buffer ();

  b->base_buffer = (XBUFFER (base_buffer)->base_buffer
		    ? XBUFFER (base_buffer)->base_buffer
		    : XBUFFER (base_buffer));

  /* Use the base buffer's text object.  */
  b->text = b->base_buffer->text;

  BUF_BEGV (b) = BUF_BEGV (b->base_buffer);
  BUF_ZV (b) = BUF_ZV (b->base_buffer);
  BUF_PT (b) = BUF_PT (b->base_buffer);
  BUF_BEGV_BYTE (b) = BUF_BEGV_BYTE (b->base_buffer);
  BUF_ZV_BYTE (b) = BUF_ZV_BYTE (b->base_buffer);
  BUF_PT_BYTE (b) = BUF_PT_BYTE (b->base_buffer);

  b->newline_cache = 0;
  b->width_run_cache = 0;
  b->width_table = Qnil;

  /* Put this on the chain of all buffers including killed ones.  */
  b->next = all_buffers;
  all_buffers = b;

  name = Fcopy_sequence (name);
  STRING_SET_INTERVALS (name, NULL_INTERVAL);
  b->name = name;

  reset_buffer (b);
  reset_buffer_local_variables (b, 1);

  /* Put this in the alist of all live buffers.  */
  XSETBUFFER (buf, b);
  Vbuffer_alist = nconc2 (Vbuffer_alist, Fcons (Fcons (name, buf), Qnil));

  b->mark = Fmake_marker ();
  b->name = name;

  /* The multibyte status belongs to the base buffer.  */
  b->enable_multibyte_characters = b->base_buffer->enable_multibyte_characters;

  /* Make sure the base buffer has markers for its narrowing.  */
  if (NILP (b->base_buffer->pt_marker))
    {
      b->base_buffer->pt_marker = Fmake_marker ();
      set_marker_both (b->base_buffer->pt_marker, base_buffer,
		       BUF_PT (b->base_buffer),
		       BUF_PT_BYTE (b->base_buffer));
    }
  if (NILP (b->base_buffer->begv_marker))
    {
      b->base_buffer->begv_marker = Fmake_marker ();
      set_marker_both (b->base_buffer->begv_marker, base_buffer,
		       BUF_BEGV (b->base_buffer),
		       BUF_BEGV_BYTE (b->base_buffer));
    }
  if (NILP (b->base_buffer->zv_marker))
    {
      b->base_buffer->zv_marker = Fmake_marker ();
      set_marker_both (b->base_buffer->zv_marker, base_buffer,
		       BUF_ZV (b->base_buffer),
		       BUF_ZV_BYTE (b->base_buffer));
      XMARKER (b->base_buffer->zv_marker)->insertion_type = 1;
    }

  if (NILP (clone))
    {
      /* Give the indirect buffer markers for its narrowing.  */
      b->pt_marker = Fmake_marker ();
      set_marker_both (b->pt_marker, buf, BUF_PT (b), BUF_PT_BYTE (b));
      b->begv_marker = Fmake_marker ();
      set_marker_both (b->begv_marker, buf, BUF_BEGV (b), BUF_BEGV_BYTE (b));
      b->zv_marker = Fmake_marker ();
      set_marker_both (b->zv_marker, buf, BUF_ZV (b), BUF_ZV_BYTE (b));
      XMARKER (b->zv_marker)->insertion_type = 1;
    }
  else
    {
      struct buffer *old_b = current_buffer;

      clone_per_buffer_values (b->base_buffer, b);
      b->filename = Qnil;
      b->file_truename = Qnil;
      b->display_count = make_number (0);
      b->backed_up = Qnil;
      b->auto_save_file_name = Qnil;
      set_buffer_internal_1 (b);
      Fset (intern ("buffer-save-without-query"), Qnil);
      Fset (intern ("buffer-file-number"), Qnil);
      Fset (intern ("buffer-stale-function"), Qnil);
      set_buffer_internal_1 (old_b);
    }

  return buf;
}

void
delete_all_overlays (b)
     struct buffer *b;
{
  Lisp_Object overlay;

  /* `reset_buffer' blindly sets the list of overlays to NULL, so we
     have to empty the list, otherwise we end up with overlays that
     think they belong to this buffer while the buffer doesn't know about
     them any more.  */
  while (b->overlays_before)
    {
      XSETMISC (overlay, b->overlays_before);
      Fdelete_overlay (overlay);
    }
  while (b->overlays_after)
    {
      XSETMISC (overlay, b->overlays_after);
      Fdelete_overlay (overlay);
    }
  eassert (b->overlays_before == NULL);
  eassert (b->overlays_after == NULL);
}

/* Reinitialize everything about a buffer except its name and contents
   and local variables.
   If called on an already-initialized buffer, the list of overlays
   should be deleted before calling this function, otherwise we end up
   with overlays that claim to belong to the buffer but the buffer
   claims it doesn't belong to it.  */

void
reset_buffer (b)
     register struct buffer *b;
{
  b->filename = Qnil;
  b->file_truename = Qnil;
  b->directory = (current_buffer) ? current_buffer->directory : Qnil;
  b->modtime = 0;
  XSETFASTINT (b->save_length, 0);
  b->last_window_start = 1;
  /* It is more conservative to start out "changed" than "unchanged".  */
  b->clip_changed = 0;
  b->prevent_redisplay_optimizations_p = 1;
  b->backed_up = Qnil;
  b->auto_save_modified = 0;
  b->auto_save_failure_time = -1;
  b->auto_save_file_name = Qnil;
  b->read_only = Qnil;
  b->overlays_before = NULL;
  b->overlays_after = NULL;
  b->overlay_center = BEG;
  b->mark_active = Qnil;
  b->point_before_scroll = Qnil;
  b->file_format = Qnil;
  b->auto_save_file_format = Qt;
  b->last_selected_window = Qnil;
  XSETINT (b->display_count, 0);
  b->display_time = Qnil;
  b->enable_multibyte_characters = buffer_defaults.enable_multibyte_characters;
  b->cursor_type = buffer_defaults.cursor_type;
  b->extra_line_spacing = buffer_defaults.extra_line_spacing;

  b->display_error_modiff = 0;
}

/* Reset buffer B's local variables info.
   Don't use this on a buffer that has already been in use;
   it does not treat permanent locals consistently.
   Instead, use Fkill_all_local_variables.

   If PERMANENT_TOO is 1, then we reset permanent built-in
   buffer-local variables.  If PERMANENT_TOO is 0,
   we preserve those.  */

static void
reset_buffer_local_variables (b, permanent_too)
     register struct buffer *b;
     int permanent_too;
{
  register int offset;
  int i;

  /* Reset the major mode to Fundamental, together with all the
     things that depend on the major mode.
     default-major-mode is handled at a higher level.
     We ignore it here.  */
  b->major_mode = Qfundamental_mode;
  b->keymap = Qnil;
  b->mode_name = QSFundamental;
  b->minor_modes = Qnil;

  /* If the standard case table has been altered and invalidated,
     fix up its insides first.  */
  if (! (CHAR_TABLE_P (XCHAR_TABLE (Vascii_downcase_table)->extras[0])
	 && CHAR_TABLE_P (XCHAR_TABLE (Vascii_downcase_table)->extras[1])
	 && CHAR_TABLE_P (XCHAR_TABLE (Vascii_downcase_table)->extras[2])))
    Fset_standard_case_table (Vascii_downcase_table);

  b->downcase_table = Vascii_downcase_table;
  b->upcase_table = XCHAR_TABLE (Vascii_downcase_table)->extras[0];
  b->case_canon_table = XCHAR_TABLE (Vascii_downcase_table)->extras[1];
  b->case_eqv_table = XCHAR_TABLE (Vascii_downcase_table)->extras[2];
  b->invisibility_spec = Qt;
#ifndef DOS_NT
  b->buffer_file_type = Qnil;
#endif

  /* Reset all (or most) per-buffer variables to their defaults.  */
  b->local_var_alist = Qnil;
  for (i = 0; i < last_per_buffer_idx; ++i)
    if (permanent_too || buffer_permanent_local_flags[i] == 0)
      SET_PER_BUFFER_VALUE_P (b, i, 0);

  /* For each slot that has a default value,
     copy that into the slot.  */

  for (offset = PER_BUFFER_VAR_OFFSET (name);
       offset < sizeof *b;
       offset += sizeof (Lisp_Object))
    {
      int idx = PER_BUFFER_IDX (offset);
      if ((idx > 0
	   && (permanent_too
	       || buffer_permanent_local_flags[idx] == 0))
	  /* Is -2 used anywhere?  */
	  || idx == -2)
	PER_BUFFER_VALUE (b, offset) = PER_BUFFER_DEFAULT (offset);
    }
}

/* We split this away from generate-new-buffer, because rename-buffer
   and set-visited-file-name ought to be able to use this to really
   rename the buffer properly.  */

DEFUN ("generate-new-buffer-name", Fgenerate_new_buffer_name, Sgenerate_new_buffer_name,
       1, 2, 0,
       doc: /* Return a string that is the name of no existing buffer based on NAME.
If there is no live buffer named NAME, then return NAME.
Otherwise modify name by appending `<NUMBER>', incrementing NUMBER
\(starting at 2) until an unused name is found, and then return that name.
Optional second argument IGNORE specifies a name that is okay to use (if
it is in the sequence to be tried) even if a buffer with that name exists.  */)
     (name, ignore)
     register Lisp_Object name, ignore;
{
  register Lisp_Object gentemp, tem;
  int count;
  char number[10];

  CHECK_STRING (name);

  tem = Fstring_equal (name, ignore);
  if (!NILP (tem))
    return name;
  tem = Fget_buffer (name);
  if (NILP (tem))
    return name;

  count = 1;
  while (1)
    {
      sprintf (number, "<%d>", ++count);
      gentemp = concat2 (name, build_string (number));
      tem = Fstring_equal (gentemp, ignore);
      if (!NILP (tem))
	return gentemp;
      tem = Fget_buffer (gentemp);
      if (NILP (tem))
	return gentemp;
    }
}


DEFUN ("buffer-name", Fbuffer_name, Sbuffer_name, 0, 1, 0,
       doc: /* Return the name of BUFFER, as a string.
With no argument or nil as argument, return the name of the current buffer.  */)
     (buffer)
     register Lisp_Object buffer;
{
  if (NILP (buffer))
    return current_buffer->name;
  CHECK_BUFFER (buffer);
  return XBUFFER (buffer)->name;
}

DEFUN ("buffer-file-name", Fbuffer_file_name, Sbuffer_file_name, 0, 1, 0,
       doc: /* Return name of file BUFFER is visiting, or nil if none.
No argument or nil as argument means use the current buffer.  */)
     (buffer)
     register Lisp_Object buffer;
{
  if (NILP (buffer))
    return current_buffer->filename;
  CHECK_BUFFER (buffer);
  return XBUFFER (buffer)->filename;
}

DEFUN ("buffer-base-buffer", Fbuffer_base_buffer, Sbuffer_base_buffer,
       0, 1, 0,
       doc: /* Return the base buffer of indirect buffer BUFFER.
If BUFFER is not indirect, return nil.
BUFFER defaults to the current buffer.  */)
     (buffer)
     register Lisp_Object buffer;
{
  struct buffer *base;
  Lisp_Object base_buffer;

  if (NILP (buffer))
    base = current_buffer->base_buffer;
  else
    {
      CHECK_BUFFER (buffer);
      base = XBUFFER (buffer)->base_buffer;
    }

  if (! base)
    return Qnil;
  XSETBUFFER (base_buffer, base);
  return base_buffer;
}

DEFUN ("buffer-local-value", Fbuffer_local_value,
       Sbuffer_local_value, 2, 2, 0,
       doc: /* Return the value of VARIABLE in BUFFER.
If VARIABLE does not have a buffer-local binding in BUFFER, the value
is the default binding of the variable. */)
     (variable, buffer)
     register Lisp_Object variable;
     register Lisp_Object buffer;
{
  register struct buffer *buf;
  register Lisp_Object result;

  CHECK_SYMBOL (variable);
  CHECK_BUFFER (buffer);
  buf = XBUFFER (buffer);

  variable = indirect_variable (variable);

  /* Look in local_var_list */
  result = Fassoc (variable, buf->local_var_alist);
  if (NILP (result))
    {
      int offset, idx;
      int found = 0;

      /* Look in special slots */
      for (offset = PER_BUFFER_VAR_OFFSET (name);
	   offset < sizeof (struct buffer);
	   /* sizeof EMACS_INT == sizeof Lisp_Object */
	   offset += (sizeof (EMACS_INT)))
	{
	  idx = PER_BUFFER_IDX (offset);
	  if ((idx == -1 || PER_BUFFER_VALUE_P (buf, idx))
	      && SYMBOLP (PER_BUFFER_SYMBOL (offset))
	      && EQ (PER_BUFFER_SYMBOL (offset), variable))
	    {
	      result = PER_BUFFER_VALUE (buf, offset);
	      found = 1;
	      break;
	    }
	}

      if (!found)
	result = Fdefault_value (variable);
    }
  else
    {
      Lisp_Object valcontents;
      Lisp_Object current_alist_element;

      /* What binding is loaded right now?  */
      valcontents = SYMBOL_VALUE (variable);
      current_alist_element
	= XCAR (XBUFFER_LOCAL_VALUE (valcontents)->cdr);

      /* The value of the currently loaded binding is not
	 stored in it, but rather in the realvalue slot.
	 Store that value into the binding it belongs to
	 in case that is the one we are about to use.  */

      Fsetcdr (current_alist_element,
	       do_symval_forwarding (XBUFFER_LOCAL_VALUE (valcontents)->realvalue));

      /* Now get the (perhaps updated) value out of the binding.  */
      result = XCDR (result);
    }

  if (!EQ (result, Qunbound))
    return result;

  xsignal1 (Qvoid_variable, variable);