buffer.c

/* Buffer manipulation primitives for GNU Emacs.
   Copyright (C) 1985, 1986, 1987, 1988, 1989, 1993, 1994
	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, 675 Mass Ave, Cambridge, MA 02139, USA.  */


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

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

#include <config.h>
#include "lisp.h"
#include "intervals.h"
#include "window.h"
#include "commands.h"
#include "buffer.h"
#include "indent.h"
#include "blockinput.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.  When a tag does not match, the function
   buffer_slot_type_mismatch will signal an error.  */
struct buffer buffer_local_types;

Lisp_Object Fset_buffer ();
void set_buffer_internal ();
static void call_overlay_mod_hooks ();

/* 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 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;

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; */

nsberror (spec)
     Lisp_Object spec;
{
  if (STRINGP (spec))
    error ("No buffer named %s", XSTRING (spec)->data);
  error ("Invalid buffer argument");
}

DEFUN ("buffer-list", Fbuffer_list, Sbuffer_list, 0, 0, 0,
  "Return a list of all existing live buffers.")
  ()
{
  return Fmapcar (Qcdr, Vbuffer_alist);
}

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 (Fassoc (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 = XCONS (tail)->cdr)
    {
      buf = Fcdr (XCONS (tail)->car);
      if (!BUFFERP (buf)) continue;
      if (!STRINGP (XBUFFER (buf)->filename)) continue;
      tem = Fstring_equal (XBUFFER (buf)->filename, 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, function, tem;
  int count = specpdl_ptr - specpdl;
  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 *) xmalloc (sizeof (struct buffer));

  BUF_GAP_SIZE (b) = 20;
  BLOCK_INPUT;
  BUFFER_ALLOC (BUF_BEG_ADDR (b), BUF_GAP_SIZE (b));
  UNBLOCK_INPUT;
  if (! BUF_BEG_ADDR (b))
    memory_full ();

  BUF_PT (b) = 1;
  BUF_GPT (b) = 1;
  BUF_BEGV (b) = 1;
  BUF_ZV (b) = 1;
  BUF_Z (b) = 1;
  BUF_MODIFF (b) = 1;

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

  b->mark = Fmake_marker ();
  /*b->number = make_number (++buffer_count);*/
  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);

  /* 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->markers = Qnil;
  b->name = name;

  function = buffer_defaults.major_mode;
  if (NILP (function))
    {
      tem = Fget (current_buffer->major_mode, Qmode_class);
      if (EQ (tem, Qnil))
	function = current_buffer->major_mode;
    }

  if (NILP (function) || EQ (function, Qfundamental_mode))
    return buf;

  /* To select a nonfundamental mode,
     select the buffer temporarily and then call the mode function. */

  record_unwind_protect (save_excursion_restore, save_excursion_save ());

  Fset_buffer (buf);
  call0 (function);

  return unbind_to (count, 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->directory = (current_buffer) ? current_buffer->directory : Qnil;
  b->modtime = 0;
  b->save_modified = 1;
  XSETFASTINT (b->save_length, 0);
  b->last_window_start = 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;

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  INITIALIZE_INTERVAL (b, NULL_INTERVAL);
}

/* 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.  */

reset_buffer_local_variables (b)
     register struct buffer *b;
{
  register int offset;

  /* 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;
  b->downcase_table = Vascii_downcase_table;
  b->upcase_table = Vascii_upcase_table;
  b->case_canon_table = Vascii_canon_table;
  b->case_eqv_table = Vascii_eqv_table;
#if 0
  b->sort_table = XSTRING (Vascii_sort_table);
  b->folding_sort_table = XSTRING (Vascii_folding_sort_table);
#endif /* 0 */

  /* Reset all per-buffer variables to their defaults.  */
  b->local_var_alist = Qnil;
  b->local_var_flags = 0;

  /* 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 || 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-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;

  {
    /* Reference each variable in the alist in our current buffer.
       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.  */
    register Lisp_Object tail;
    for (tail = buf->local_var_alist; CONSP (tail); tail = XCONS (tail)->cdr)
      {
	Lisp_Object val, elt;

	elt = XCONS (tail)->car;

	if (buf == current_buffer)
	  val = find_symbol_value (XCONS (elt)->car);
	else
	  val = XCONS (elt)->cdr;

	/* If symbol is unbound, put just the symbol in the list.  */
	if (EQ (val, Qunbound))
	  result = Fcons (XCONS (elt)->car, result);
	/* Otherwise, put (symbol . value) in the list.  */
	else
	  result = Fcons (Fcons (XCONS (elt)->car, 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_modified < 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;

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

  fn = current_buffer->filename;
  if (!NILP (fn))
    {
      already = current_buffer->save_modified < MODIFF;
      if (!already && !NILP (flag))
	lock_file (fn);
      else if (already && NILP (flag))
	unlock_file (fn);
    }
#endif /* CLASH_DETECTION */

  current_buffer->save_modified = NILP (flag) ? MODIFF : 0;
  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).")
  (name, unique)
     register Lisp_Object name, unique;
{
  register Lisp_Object tem, buf;

  CHECK_STRING (name, 0);

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

  tem = Fget_buffer (name);
  /* 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 NAME)).  */
  if (NILP (unique) && XBUFFER (tem) == current_buffer)
    return current_buffer->name;
  if (!NILP (tem))
    {
      if (!NILP (unique))
	name = Fgenerate_new_buffer_name (name, current_buffer->name);
      else
	error ("Buffer name \"%s\" is in use", XSTRING (name)->data);
    }

  current_buffer->name = name;

  /* 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), name);
  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, 2, 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 no other buffer exists, the buffer `*scratch*' is returned.\n\
If BUFFER is omitted or nil, some interesting buffer is returned.")
  (buffer, visible_ok)
     register Lisp_Object buffer, visible_ok;
{
  register Lisp_Object tail, buf, notsogood, tem;
  notsogood = Qnil;

  for (tail = Vbuffer_alist; !NILP (tail); tail = Fcdr (tail))
    {
      buf = Fcdr (Fcar (tail));
      if (EQ (buf, buffer))
	continue;
      if (XSTRING (XBUFFER (buf)->name)->data[0] == ' ')
	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;
  return Fget_buffer_create (build_string ("*scratch*"));
}

DEFUN ("buffer-disable-undo", Fbuffer_disable_undo, Sbuffer_disable_undo, 0, 1,
0,
  "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\
when the hook functions are called.\n\n\
Any processes that have this buffer as the `process-buffer' are killed\n\
with `delete-process'.")
  (bufname)
     Lisp_Object bufname;
{
  Lisp_Object buf;
  register struct buffer *b;
  register Lisp_Object tem;
  register struct Lisp_Marker *m;
  struct gcpro gcpro1, gcpro2;

  if (NILP (bufname))
    buf = Fcurrent_buffer ();
  else
    buf = Fget_buffer (bufname);
  if (NILP (buf))
    nsberror (bufname);

  b = XBUFFER (buf);

  /* Query if the buffer is still modified.  */
  if (INTERACTIVE && !NILP (b->filename)
      && BUF_MODIFF (b) > b->save_modified)
    {
      GCPRO2 (buf, bufname);
      tem = do_yes_or_no_p (format1 ("Buffer %s modified; kill anyway? ",
				     XSTRING (b->name)->data));
      UNGCPRO;
      if (NILP (tem))
	return Qnil;
    }

  /* Run hooks with the buffer to be killed the current buffer.  */
  {
    register Lisp_Object val;
    int count = specpdl_ptr - specpdl;
    Lisp_Object list;

    record_unwind_protect (save_excursion_restore, save_excursion_save ());
    set_buffer_internal (b);

    /* First run the query functions; if any query is answered no,
       don't kill the buffer.  */
    for (list = Vkill_buffer_query_functions; !NILP (list); list = Fcdr (list))
      {
	tem = call0 (Fcar (list));
	if (NILP (tem))
	  return unbind_to (count, Qnil);
      }

    /* Then run the hooks.  */
    if (!NILP (Vrun_hooks))
      call1 (Vrun_hooks, Qkill_buffer_hook);
    unbind_to (count, Qnil);
  }

  /* We have no more questions to ask.  Verify that it is valid
     to kill the buffer.  This must be done after the questions
     since anything can happen within do_yes_or_no_p.  */

  /* Don't kill the minibuffer now current.  */
  if (EQ (buf, XWINDOW (minibuf_window)->buffer))
    return Qnil;

  if (NILP (b->name))
    return Qnil;

  /* Make this buffer not be current.
     In the process, notice if this is the sole visible buffer
     and give up if so.  */
  if (b == current_buffer)
    {
      tem = Fother_buffer (buf, Qnil);
      Fset_buffer (tem);
      if (b == current_buffer)
	return Qnil;
    }

  /* Now there is no question: we can kill the buffer.  */

#ifdef CLASH_DETECTION
  /* Unlock this buffer's file, if it is locked.  */
  unlock_buffer (b);
#endif /* CLASH_DETECTION */

  kill_buffer_processes (buf);

  tem = Vinhibit_quit;
  Vinhibit_quit = Qt;
  Vbuffer_alist = Fdelq (Frassq (buf, Vbuffer_alist), Vbuffer_alist);
  Freplace_buffer_in_windows (buf);
  Vinhibit_quit = tem;

  /* Delete any auto-save file, if we saved it in this session.  */
  if (STRINGP (b->auto_save_file_name)
      && b->auto_save_modified != 0)
    {
      Lisp_Object tem;
      tem = Fsymbol_value (intern ("delete-auto-save-files"));
      if (! NILP (tem))
	unlink (XSTRING (b->auto_save_file_name)->data);
    }

  /* Unchain all markers of this buffer
     and leave them pointing nowhere.  */
  for (tem = b->markers; !EQ (tem, Qnil); )
    {
      m = XMARKER (tem);
      m->buffer = 0;
      tem = m->chain;
      m->chain = Qnil;
    }
  b->markers = Qnil;

  /* Only defined if Emacs is compiled with USE_TEXT_PROPERTIES */
  INITIALIZE_INTERVAL (b, NULL_INTERVAL);
  /* Perhaps we should explicitly free the interval tree here... */

  b->name = Qnil;
  BLOCK_INPUT;
  BUFFER_FREE (BUF_BEG_ADDR (b));
  UNBLOCK_INPUT;
  b->undo_list = Qnil;

  return Qt;
}

/* Move the assoc for buffer BUF to the front of buffer-alist.  Since
   we do this each time BUF is selected visibly, the more recently
   selected buffers are always closer to the front of the list.  This
   means that other_buffer is more likely to choose a relevant buffer.  */

record_buffer (buf)
     Lisp_Object buf;
{
  register Lisp_Object link, prev;

  prev = Qnil;
  for (link = Vbuffer_alist; CONSP (link); link = XCONS (link)->cdr)
    {
      if (EQ (XCONS (XCONS (link)->car)->cdr, buf))
	break;
      prev = link;
    }

  /* Effectively do Vbuffer_alist = Fdelq (link, Vbuffer_alist);
     we cannot use Fdelq itself here because it allows quitting.  */

  if (NILP (prev))
    Vbuffer_alist = XCONS (Vbuffer_alist)->cdr;
  else
    XCONS (prev)->cdr = XCONS (XCONS (prev)->cdr)->cdr;
	
  XCONS(link)->cdr = Vbuffer_alist;
  Vbuffer_alist = link;
}

DEFUN ("switch-to-buffer", Fswitch_to_buffer, Sswitch_to_buffer, 1, 2, "BSwitch to buffer: ",
  "Select buffer BUFFER in the current window.\n\
BUFFER may be a buffer or a buffer name.\n\
Optional second arg NORECORD non-nil means\n\
do not put this buffer at the front of the list of recently selected ones.\n\
\n\
WARNING: This is NOT the way to work on another buffer temporarily\n\
within a Lisp program!  Use `set-buffer' instead.  That avoids messing with\n\
the window-buffer correspondences.")
  (bufname, norecord)
     Lisp_Object bufname, norecord;
{
  register Lisp_Object buf;
  Lisp_Object tem;

  if (EQ (minibuf_window, selected_window))
    error ("Cannot switch buffers in minibuffer window");
  tem = Fwindow_dedicated_p (selected_window);
  if (!NILP (tem))
    error ("Cannot switch buffers in a dedicated window");

  if (NILP (bufname))
    buf = Fother_buffer (Fcurrent_buffer (), Qnil);
  else
    buf = Fget_buffer_create (bufname);
  Fset_buffer (buf);
  if (NILP (norecord))
    record_buffer (buf);

  Fset_window_buffer (EQ (selected_window, minibuf_window)
		      ? Fnext_window (minibuf_window, Qnil, Qnil)
		      : selected_window,
		      buf);

  return buf;
}

DEFUN ("pop-to-buffer", Fpop_to_buffer, Spop_to_buffer, 1, 2, 0,
  "Select buffer BUFFER in some window, preferably a different one.\n\
If BUFFER is nil, then some other buffer is chosen.\n\
If `pop-up-windows' is non-nil, windows can be split to do this.\n\
If optional second arg OTHER-WINDOW is non-nil, insist on finding another\n\
window even if BUFFER is already visible in the selected window.")
  (bufname, other)
     Lisp_Object bufname, other;
{
  register Lisp_Object buf;
  if (NILP (bufname))
    buf = Fother_buffer (Fcurrent_buffer (), Qnil);
  else
    buf = Fget_buffer_create (bufname);
  Fset_buffer (buf);
  record_buffer (buf);
  Fselect_window (Fdisplay_buffer (buf, other));
  return buf;
}

DEFUN ("current-buffer", Fcurrent_buffer, Scurrent_buffer, 0, 0, 0,
  "Return the current buffer as a Lisp object.")
  ()
{
  register Lisp_Object buf;
  XSETBUFFER (buf, current_buffer);
  return buf;
}

/* Set the current buffer to b */

void
set_buffer_internal (b)
     register struct buffer *b;
{
  register struct buffer *old_buf;
  register Lisp_Object tail, valcontents;
  Lisp_Object tem;

  if (current_buffer == b)
    return;

  windows_or_buffers_changed = 1;
  old_buf = current_buffer;
  current_buffer = b;
  last_known_column_point = -1;   /* invalidate indentation cache */

  /* Look down buffer's list of local Lisp variables
     to find and update any that forward into C variables. */

  for (tail = b->local_var_alist; !NILP (tail); tail = XCONS (tail)->cdr)
    {
      valcontents = XSYMBOL (XCONS (XCONS (tail)->car)->car)->value;
      if ((BUFFER_LOCAL_VALUEP (valcontents)
	   || SOME_BUFFER_LOCAL_VALUEP (valcontents))
	  && (tem = XCONS (valcontents)->car,
	      (BOOLFWDP (tem) || INTFWDP (tem) || OBJFWDP (tem))))
	/* Just reference the variable
	     to cause it to become set for this buffer.  */
	Fsymbol_value (XCONS (XCONS (tail)->car)->car);
    }

  /* Do the same with any others that were local to the previous buffer */

  if (old_buf)
    for (tail = old_buf->local_var_alist; !NILP (tail); tail = XCONS (tail)->cdr)
      {
	valcontents = XSYMBOL (XCONS (XCONS (tail)->car)->car)->value;
	if ((BUFFER_LOCAL_VALUEP (valcontents)
	     || SOME_BUFFER_LOCAL_VALUEP (valcontents))
	    && (tem = XCONS (valcontents)->car,
		(BOOLFWDP (tem) || INTFWDP (tem) || OBJFWDP (tem))))
	  /* Just reference the variable
               to cause it to become set for this buffer.  */
	  Fsymbol_value (XCONS (XCONS (tail)->car)->car);
      }
}

DEFUN ("set-buffer", Fset_buffer, Sset_buffer, 1, 1, 0,
  "Make the buffer BUFFER current for editing operations.\n\
BUFFER may be a buffer or the name of an existing buffer.\n\
See also `save-excursion' when you want to make a buffer current temporarily.\n\
This function does not display the buffer, so its effect ends\n\
when the current command terminates.\n\
Use `switch-to-buffer' or `pop-to-buffer' to switch buffers permanently.")
  (bufname)
     register Lisp_Object bufname;
{
  register Lisp_Object buffer;
  buffer = Fget_buffer (bufname);
  if (NILP (buffer))
    nsberror (bufname);
  if (NILP (XBUFFER (buffer)->name))
    error ("Selecting deleted buffer");
  set_buffer_internal (XBUFFER (buffer));
  return buffer;
}

DEFUN ("barf-if-buffer-read-only", Fbarf_if_buffer_read_only,
				   Sbarf_if_buffer_read_only, 0, 0, 0,
  "Signal a `buffer-read-only' error if the current buffer is read-only.")
  ()
{
  if (!NILP (current_buffer->read_only)
      && NILP (Vinhibit_read_only))
    Fsignal (Qbuffer_read_only, (Fcons (Fcurrent_buffer (), Qnil)));
  return Qnil;
}

DEFUN ("bury-buffer", Fbury_buffer, Sbury_buffer, 0, 1, "",
  "Put BUFFER at the end of the list of all buffers.\n\
There it is the least likely candidate for `other-buffer' to return;\n\
thus, the least likely buffer for \\[switch-to-buffer] to select by default.\n\
If BUFFER is nil or omitted, bury the current buffer.\n\
Also, if BUFFER is nil or omitted, remove the current buffer from the\n\
selected window if it is displayed there.")
  (buf)
     register Lisp_Object buf;
{
  /* Figure out what buffer we're going to bury.  */
  if (NILP (buf))
    {
      XSETBUFFER (buf, current_buffer);

      /* If we're burying the current buffer, unshow it.  */
      Fswitch_to_buffer (Fother_buffer (buf, Qnil), Qnil);
    }
  else
    {
      Lisp_Object buf1;
      
      buf1 = Fget_buffer (buf);
      if (NILP (buf1))
	nsberror (buf);
      buf = buf1;
    }

  /* Move buf to the end of the buffer list.  */
  {
    register Lisp_Object aelt, link;

    aelt = Frassq (buf, Vbuffer_alist);
    link = Fmemq (aelt, Vbuffer_alist);
    Vbuffer_alist = Fdelq (aelt, Vbuffer_alist);
    XCONS (link)->cdr = Qnil;
    Vbuffer_alist = nconc2 (Vbuffer_alist, link);
  }

  return Qnil;
}

DEFUN ("erase-buffer", Ferase_buffer, Serase_buffer, 0, 0, "*",
  "Delete the entire contents of the current buffer.\n\
Any narrowing restriction in effect (see `narrow-to-region') is removed,\n\
so the buffer is truly empty after this.")
  ()
{
  Fwiden ();
  del_range (BEG, Z);
  current_buffer->last_window_start = 1;
  /* Prevent warnings, or suspension of auto saving, that would happen
     if future size is less than past size.  Use of erase-buffer
     implies that the future text is not really related to the past text.  */
  XSETFASTINT (current_buffer->save_length, 0);
  return Qnil;
}

validate_region (b, e)
     register Lisp_Object *b, *e;
{
  CHECK_NUMBER_COERCE_MARKER (*b, 0);
  CHECK_NUMBER_COERCE_MARKER (*e, 1);

  if (XINT (*b) > XINT (*e))
    {
      Lisp_Object tem;
      tem = *b;  *b = *e;  *e = tem;
    }

  if (!(BEGV <= XINT (*b) && XINT (*b) <= XINT (*e)
        && XINT (*e) <= ZV))
    args_out_of_range (*b, *e);
}

static Lisp_Object
list_buffers_1 (files)
     Lisp_Object files;
{
  register Lisp_Object tail, tem, buf;
  Lisp_Object col1, col2, col3, minspace;
  register struct buffer *old = current_buffer, *b;
  Lisp_Object desired_point;
  Lisp_Object other_file_symbol;

  desired_point = Qnil;
  other_file_symbol = intern ("list-buffers-directory");

  XSETFASTINT (col1, 19);
  XSETFASTINT (col2, 26);
  XSETFASTINT (col3, 40);
  XSETFASTINT (minspace, 1);

  Fset_buffer (Vstandard_output);
  Fbuffer_disable_undo (Vstandard_output);
  current_buffer->read_only = Qnil;

  write_string ("\
 MR Buffer         Size   Mode           File\n\
 -- ------         ----   ----           ----\n", -1);

  for (tail = Vbuffer_alist; !NILP (tail); tail = Fcdr (tail))
    {
      buf = Fcdr (Fcar (tail));
      b = XBUFFER (buf);
      /* Don't mention the minibuffers. */
      if (XSTRING (b->name)->data[0] == ' ')
	continue;
      /* Optionally don't mention buffers that lack files. */
      if (!NILP (files) && NILP (b->filename))
	continue;
      /* Identify the current buffer. */
      if (b == old)
	XSETFASTINT (desired_point, point);
      write_string (b == old ? "." : " ", -1);
      /* Identify modified buffers */
      write_string (BUF_MODIFF (b) > b->save_modified ? "*" : " ", -1);