buffer.c

/* Buffer manipulation primitives for GNU Emacs.
   Copyright (C) 1985,86,87,88,89,93,94,95,97,98, 1999
	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 2, 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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include <config.h>

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

extern int errno;

#ifndef MAXPATHLEN
/* in 4.1, param.h fails to define this. */
#define MAXPATHLEN 1024
#endif /* not MAXPATHLEN */

#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 "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.  */

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 bit for that slot (found in the same slot in this structure)
   is turned on in the buffer's local_var_flags slot.

   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 is negative, 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 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. */

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

/* This structure holds the required types for the values in the
   buffer-local slots.  If a slot contains Qnil, then the
   corresponding buffer slot may contain a value of any type.  If a
   slot contains an integer, then prospective values' tags must be
   equal to that integer (except nil is always allowed).
   When a tag does not match, the function
   buffer_slot_type_mismatch will signal an error.

   If a slot here contains -1, the corresponding variable is read-only.  */
struct buffer buffer_local_types;

/* Flags indicating which built-in buffer-local variables
   are permanent locals.  */
static int buffer_permanent_local_flags;

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_function;
Lisp_Object Vafter_change_function;
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;

/* 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;

/* 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;

/* 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", XSTRING (spec)->data);
  error ("Invalid buffer argument");
}

DEFUN ("buffer-live-p", Fbuffer_live_p, Sbuffer_live_p, 1, 1, 0,
  "Return non-nil if OBJECT is a buffer which has not been killed.\n\
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,
  "Return a list of all existing live buffers.\n\
If the optional arg FRAME is a frame, we return that frame's buffer list.")
  (frame)
     Lisp_Object frame;
{
  Lisp_Object framelist, general;
  general = Fmapcar (Qcdr, Vbuffer_alist);

  if (FRAMEP (frame))
    {
      Lisp_Object tail;

      CHECK_FRAME (frame, 1);

      framelist = Fcopy_sequence (XFRAME (frame)->buffer_list);

      /* Remove from GENERAL any buffer that duplicates one in FRAMELIST.  */
      tail = framelist;
      while (! NILP (tail))
	{
	  general = Fdelq (XCAR (tail), general);
	  tail = XCDR (tail);
	}
      return nconc2 (framelist, general);
    }

  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; !NILP (tail); tail = Fcdr (tail))
    {
      register Lisp_Object elt, tem;
      elt = Fcar (tail);
      tem = Fstring_equal (Fcar (elt), key);
      if (!NILP (tem))
	return elt;
    }
  return Qnil;
}

DEFUN ("get-buffer", Fget_buffer, Sget_buffer, 1, 1, 0,
  "Return the buffer named NAME (a string).\n\
If there is no live buffer named NAME, return nil.\n\
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, 0);

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

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

  CHECK_STRING (filename, 0);
  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,
  "Return the buffer named NAME, or create such a buffer and return it.\n\
A new buffer is created if there is no live buffer named NAME.\n\
If NAME starts with a space, the new buffer does not keep undo information.\n\
If NAME is a buffer instead of a string, then it is the value returned.\n\
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 (XSTRING (name)->size == 0)
    error ("Empty string for buffer name is not allowed");

  b = (struct buffer *) allocate_buffer ();

  b->size = sizeof (struct buffer) / sizeof (EMACS_INT);

  /* 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.  */
  BUFFER_ALLOC (BUF_BEG_ADDR (b), (BUF_GAP_SIZE (b) + 1));
  UNBLOCK_INPUT;
  if (! BUF_BEG_ADDR (b))
    buffer_memory_full ();

  BUF_PT (b) = 1;
  BUF_GPT (b) = 1;
  BUF_BEGV (b) = 1;
  BUF_ZV (b) = 1;
  BUF_Z (b) = 1;
  BUF_PT_BYTE (b) = 1;
  BUF_GPT_BYTE (b) = 1;
  BUF_BEGV_BYTE (b) = 1;
  BUF_ZV_BYTE (b) = 1;
  BUF_Z_BYTE (b) = 1;
  BUF_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);
  INITIALIZE_INTERVAL (XSTRING (name), NULL_INTERVAL);
  b->name = name;

  if (XSTRING (name)->data[0] != ' ')
    b->undo_list = Qnil;
  else
    b->undo_list = Qt;

  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 ();
  BUF_MARKERS (b) = Qnil;
  b->name = name;
  return buf;
}

DEFUN ("make-indirect-buffer", Fmake_indirect_buffer, Smake_indirect_buffer, 2, 2,
       "bMake indirect buffer (to buffer): \nBName of indirect buffer: ",
  "Create and return an indirect buffer for buffer BASE-BUFFER, named NAME.\n\
BASE-BUFFER should be an existing buffer (or buffer name).\n\
NAME should be a string which is not the name of an existing buffer.")
  (base_buffer, name)
     register Lisp_Object base_buffer, name;
{
  register Lisp_Object buf;
  register struct buffer *b;

  buf = Fget_buffer (name);
  if (!NILP (buf))
    error ("Buffer name `%s' is in use", XSTRING (name)->data);

  base_buffer = Fget_buffer (base_buffer);
  if (NILP (base_buffer))
    error ("No such buffer: `%s'",
	   XSTRING (XBUFFER (base_buffer)->name)->data);

  if (XSTRING (name)->size == 0)
    error ("Empty string for buffer name is not allowed");

  b = (struct buffer *) allocate_buffer ();
  b->size = sizeof (struct buffer) / sizeof (EMACS_INT);

  if (XBUFFER (base_buffer)->base_buffer)
    b->base_buffer = XBUFFER (base_buffer)->base_buffer;
  else
    b->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);
  INITIALIZE_INTERVAL (XSTRING (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;
    }

  /* 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;

  return buf;
}

/* Reinitialize everything about a buffer except its name and contents
   and local variables.  */

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 = Qnil;
  b->overlays_after = Qnil;
  XSETFASTINT (b->overlay_center, 1);
  b->mark_active = Qnil;
  b->point_before_scroll = Qnil;
  b->file_format = Qnil;
  b->last_selected_window = Qnil;
  XSETINT (b->display_count, 0);
  b->display_time = Qnil;
  b->extra2 = Qnil;
  b->extra3 = Qnil;
  b->enable_multibyte_characters = buffer_defaults.enable_multibyte_characters;
}

/* 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 dont_reset;

  /* Decide which built-in local variables to reset.  */
  if (permanent_too)
    dont_reset = 0;
  else
    dont_reset = buffer_permanent_local_flags;

  /* 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->abbrev_table = Vfundamental_mode_abbrev_table;
  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

#if 0
  b->sort_table = XSTRING (Vascii_sort_table);
  b->folding_sort_table = XSTRING (Vascii_folding_sort_table);
#endif /* 0 */

  /* Reset all (or most) per-buffer variables to their defaults.  */
  b->local_var_alist = Qnil;
  b->local_var_flags &= dont_reset;

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

  for (offset = (char *)&buffer_local_flags.name - (char *)&buffer_local_flags;
       offset < sizeof (struct buffer);
       offset += sizeof (Lisp_Object)) /* sizeof EMACS_INT == sizeof Lisp_Object */
    {
      int flag = XINT (*(Lisp_Object *)(offset + (char *)&buffer_local_flags));
      if ((flag > 0
	   /* Don't reset a permanent local.  */
	   && ! (dont_reset & flag))
	  || flag == -2)
	*(Lisp_Object *)(offset + (char *)b)
	  = *(Lisp_Object *)(offset + (char *)&buffer_defaults);
    }
}

/* 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,
  "Return a string that is the name of no existing buffer based on NAME.\n\
If there is no live buffer named NAME, then return NAME.\n\
Otherwise modify name by appending `<NUMBER>', incrementing NUMBER\n\
until an unused name is found, and then return that name.\n\
Optional second argument IGNORE specifies a name that is okay to use\n\
\(if it is in the sequence to be tried)\n\
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, 0);

  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,
  "Return the name of BUFFER, as a string.\n\
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, 0);
  return XBUFFER (buffer)->name;
}

DEFUN ("buffer-file-name", Fbuffer_file_name, Sbuffer_file_name, 0, 1, 0,
  "Return name of file BUFFER is visiting, or nil if none.\n\
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, 0);
  return XBUFFER (buffer)->filename;
}

DEFUN ("buffer-base-buffer", Fbuffer_base_buffer, Sbuffer_base_buffer,
       0, 1, 0,
  "Return the base buffer of indirect buffer BUFFER.\n\
If BUFFER is not indirect, return nil.")
  (buffer)
     register Lisp_Object buffer;
{
  struct buffer *base;
  Lisp_Object base_buffer;

  if (NILP (buffer))
    base = current_buffer->base_buffer;
  else
    {
      CHECK_BUFFER (buffer, 0);
      base = XBUFFER (buffer)->base_buffer;
    }

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

DEFUN ("buffer-local-variables", Fbuffer_local_variables,
  Sbuffer_local_variables, 0, 1, 0,
  "Return an alist of variables that are buffer-local in BUFFER.\n\
Most elements look like (SYMBOL . VALUE), describing one variable.\n\
For a symbol that is locally unbound, just the symbol appears in the value.\n\
Note that storing new VALUEs in these elements doesn't change the variables.\n\
No argument or nil as argument means use current buffer as BUFFER.")
  (buffer)
     register Lisp_Object buffer;
{
  register struct buffer *buf;
  register Lisp_Object result;

  if (NILP (buffer))
    buf = current_buffer;
  else
    {
      CHECK_BUFFER (buffer, 0);
      buf = XBUFFER (buffer);
    }

  result = Qnil;

  {
    register Lisp_Object tail;
    for (tail = buf->local_var_alist; CONSP (tail); tail = XCDR (tail))
      {
	Lisp_Object val, elt;

	elt = XCAR (tail);

	/* Reference each variable in the alist in buf.
	   If inquiring about the current buffer, this gets the current values,
	   so store them into the alist so the alist is up to date.
	   If inquiring about some other buffer, this swaps out any values
	   for that buffer, making the alist up to date automatically.  */
	val = find_symbol_value (XCAR (elt));
	/* Use the current buffer value only if buf is the current buffer.  */
	if (buf != current_buffer)
	  val = XCDR (elt);

	/* If symbol is unbound, put just the symbol in the list.  */
	if (EQ (val, Qunbound))
	  result = Fcons (XCAR (elt), result);
	/* Otherwise, put (symbol . value) in the list.  */
	else
	  result = Fcons (Fcons (XCAR (elt), val), result);
      }
  }

  /* Add on all the variables stored in special slots.  */
  {
    register int offset, mask;

    for (offset = (char *)&buffer_local_symbols.name - (char *)&buffer_local_symbols;
	 offset < sizeof (struct buffer);
	 offset += (sizeof (EMACS_INT))) /* sizeof EMACS_INT == sizeof Lisp_Object */
      {
	mask = XINT (*(Lisp_Object *)(offset + (char *)&buffer_local_flags));
	if (mask == -1 || (buf->local_var_flags & mask))
	  if (SYMBOLP (*(Lisp_Object *)(offset
					+ (char *)&buffer_local_symbols)))
	    result = Fcons (Fcons (*((Lisp_Object *)
				     (offset + (char *)&buffer_local_symbols)),
				   *(Lisp_Object *)(offset + (char *)buf)),
			    result);
      }
  }

  return result;
}


DEFUN ("buffer-modified-p", Fbuffer_modified_p, Sbuffer_modified_p,
  0, 1, 0,
  "Return t if BUFFER was modified since its file was last read or saved.\n\
No argument or nil as argument means use current buffer as BUFFER.")
  (buffer)
     register Lisp_Object buffer;
{
  register struct buffer *buf;
  if (NILP (buffer))
    buf = current_buffer;
  else
    {
      CHECK_BUFFER (buffer, 0);
      buf = XBUFFER (buffer);
    }

  return BUF_SAVE_MODIFF (buf) < BUF_MODIFF (buf) ? Qt : Qnil;
}

DEFUN ("set-buffer-modified-p", Fset_buffer_modified_p, Sset_buffer_modified_p,
  1, 1, 0,
  "Mark current buffer as modified or unmodified according to FLAG.\n\
A non-nil FLAG means mark the buffer modified.")
  (flag)
     register Lisp_Object flag;
{
  register int already;
  register Lisp_Object fn;
  Lisp_Object buffer, window;

#ifdef CLASH_DETECTION
  /* If buffer becoming modified, lock the file.
     If buffer becoming unmodified, unlock the file.  */

  fn = current_buffer->file_truename;
  /* Test buffer-file-name so that binding it to nil is effective.  */
  if (!NILP (fn) && ! NILP (current_buffer->filename))
    {
      already = SAVE_MODIFF < MODIFF;
      if (!already && !NILP (flag))
	lock_file (fn);
      else if (already && NILP (flag))
	unlock_file (fn);
    }
#endif /* CLASH_DETECTION */

  SAVE_MODIFF = NILP (flag) ? MODIFF : 0;
  
  /* Set update_mode_lines only if buffer is displayed in some window.
     Packages like jit-lock or lazy-lock preserve a buffer's modified
     state by recording/restoring the state around blocks of code.
     Setting update_mode_lines makes redisplay consider all windows
     (on all frames).  Stealth fontification of buffers not displayed
     would incur additional redisplay costs if we'd set
     update_modes_lines unconditionally.

     Ideally, I think there should be another mechanism for fontifying
     buffers without "modifying" buffers, or redisplay should be
     smarter about updating the `*' in mode lines.  --gerd  */
  XSETBUFFER (buffer, current_buffer);
  window = Fget_buffer_window (buffer, Qt);
  if (WINDOWP (window))
    update_mode_lines++;
  
  return flag;
}

DEFUN ("buffer-modified-tick", Fbuffer_modified_tick, Sbuffer_modified_tick,
  0, 1, 0,
  "Return BUFFER's tick counter, incremented for each change in text.\n\
Each buffer has a tick counter which is incremented each time the text in\n\
that buffer is changed.  It wraps around occasionally.\n\
No argument or nil as argument means use current buffer as BUFFER.")
  (buffer)
     register Lisp_Object buffer;
{
  register struct buffer *buf;
  if (NILP (buffer))
    buf = current_buffer;
  else
    {
      CHECK_BUFFER (buffer, 0);
      buf = XBUFFER (buffer);
    }

  return make_number (BUF_MODIFF (buf));
}

DEFUN ("rename-buffer", Frename_buffer, Srename_buffer, 1, 2,
       "sRename buffer (to new name): \nP",
  "Change current buffer's name to NEWNAME (a string).\n\
If second arg UNIQUE is nil or omitted, it is an error if a\n\
buffer named NEWNAME already exists.\n\
If UNIQUE is non-nil, come up with a new name using\n\
`generate-new-buffer-name'.\n\
Interactively, you can set UNIQUE with a prefix argument.\n\
We return the name we actually gave the buffer.\n\
This does not change the name of the visited file (if any).")
  (newname, unique)
     register Lisp_Object newname, unique;
{
  register Lisp_Object tem, buf;

  CHECK_STRING (newname, 0);

  if (XSTRING (newname)->size == 0)
    error ("Empty string is invalid as a buffer name");

  tem = Fget_buffer (newname);
  /* Don't short-circuit if UNIQUE is t.  That is a useful way to rename
     the buffer automatically so you can create another with the original name.
     It makes UNIQUE equivalent to
     (rename-buffer (generate-new-buffer-name NEWNAME)).  */
  if (NILP (unique) && XBUFFER (tem) == current_buffer)
    return current_buffer->name;
  if (!NILP (tem))
    {
      if (!NILP (unique))
	newname = Fgenerate_new_buffer_name (newname, current_buffer->name);
      else
	error ("Buffer name `%s' is in use", XSTRING (newname)->data);
    }

  current_buffer->name = newname;

  /* Catch redisplay's attention.  Unless we do this, the mode lines for
     any windows displaying current_buffer will stay unchanged.  */
  update_mode_lines++;

  XSETBUFFER (buf, current_buffer);
  Fsetcar (Frassq (buf, Vbuffer_alist), newname);
  if (NILP (current_buffer->filename)
      && !NILP (current_buffer->auto_save_file_name))
    call0 (intern ("rename-auto-save-file"));
  /* Refetch since that last call may have done GC.  */
  return current_buffer->name;
}

DEFUN ("other-buffer", Fother_buffer, Sother_buffer, 0, 3, 0,
  "Return most recently selected buffer other than BUFFER.\n\
Buffers not visible in windows are preferred to visible buffers,\n\
unless optional second argument VISIBLE-OK is non-nil.\n\
If the optional third argument FRAME is non-nil, use that frame's\n\
buffer list instead of the selected frame's buffer list.\n\
If no other buffer exists, the buffer `*scratch*' is returned.\n\
If BUFFER is omitted or nil, some interesting buffer is returned.")
  (buffer, visible_ok, frame)
     register Lisp_Object buffer, visible_ok, frame;
{
  Lisp_Object Fset_buffer_major_mode ();
  register Lisp_Object tail, buf, notsogood, tem, pred, add_ons;
  notsogood = Qnil;

  if (NILP (frame))
    frame = selected_frame;

  tail = Vbuffer_alist;
  pred = frame_buffer_predicate (frame);

  /* Consider buffers that have been seen in the selected frame
     before other buffers.  */
    
  tem = frame_buffer_list (frame);
  add_ons = Qnil;
  while (CONSP (tem))
    {
      if (BUFFERP (XCAR (tem)))
	add_ons = Fcons (Fcons (Qnil, XCAR (tem)), add_ons);
      tem = XCDR (tem);
    }
  tail = nconc2 (Fnreverse (add_ons), tail);

  for (; !NILP (tail); tail = Fcdr (tail))
    {
      buf = Fcdr (Fcar (tail));
      if (EQ (buf, buffer))
	continue;
      if (XSTRING (XBUFFER (buf)->name)->data[0] == ' ')
	continue;
      /* If the selected frame has a buffer_predicate,
	 disregard buffers that don't fit the predicate.  */
      if (!NILP (pred))
	{
	  tem = call1 (pred, buf);
	  if (NILP (tem))
	    continue;
	}

      if (NILP (visible_ok))
	tem = Fget_buffer_window (buf, Qt);
      else
	tem = Qnil;
      if (NILP (tem))
	return buf;
      if (NILP (notsogood))
	notsogood = buf;
    }
  if (!NILP (notsogood))
    return notsogood;
  buf = Fget_buffer (build_string ("*scratch*"));
  if (NILP (buf))
    {
      buf = Fget_buffer_create (build_string ("*scratch*"));
      Fset_buffer_major_mode (buf);
    }
  return buf;
}

DEFUN ("buffer-disable-undo", Fbuffer_disable_undo, Sbuffer_disable_undo,
       0, 1, "",
  "Make BUFFER stop keeping undo information.\n\
No argument or nil as argument means do this for the current buffer.")
  (buffer)
     register Lisp_Object buffer;
{
  Lisp_Object real_buffer;

  if (NILP (buffer))
    XSETBUFFER (real_buffer, current_buffer);
  else
    {
      real_buffer = Fget_buffer (buffer);
      if (NILP (real_buffer))
	nsberror (buffer);
    }

  XBUFFER (real_buffer)->undo_list = Qt;

  return Qnil;
}

DEFUN ("buffer-enable-undo", Fbuffer_enable_undo, Sbuffer_enable_undo,
       0, 1, "",
  "Start keeping undo information for buffer BUFFER.\n\
No argument or nil as argument means do this for the current buffer.")
  (buffer)
     register Lisp_Object buffer;
{
  Lisp_Object real_buffer;

  if (NILP (buffer))
    XSETBUFFER (real_buffer, current_buffer);
  else
    {
      real_buffer = Fget_buffer (buffer);
      if (NILP (real_buffer))
	nsberror (buffer);
    }

  if (EQ (XBUFFER (real_buffer)->undo_list, Qt))
    XBUFFER (real_buffer)->undo_list = Qnil;

  return Qnil;
}

/*
  DEFVAR_LISP ("kill-buffer-hook", no_cell, "\
Hook to be run (by `run-hooks', which see) when a buffer is killed.\n\
The buffer being killed will be current while the hook is running.\n\
See `kill-buffer'."
 */
DEFUN ("kill-buffer", Fkill_buffer, Skill_buffer, 1, 1, "bKill buffer: ",
  "Kill the buffer BUFFER.\n\
The argument may be a buffer or may be the name of a buffer.\n\
An argument of nil means kill the current buffer.\n\n\
Value is t if the buffer is actually killed, nil if user says no.\n\n\
The value of `kill-buffer-hook' (which may be local to that buffer),\n\
if not void, is a list of functions to be called, with no arguments,\n\
before the buffer is actually killed.  The buffer to be killed is current\n\