/* File IO for XEmacs.
   Copyright (C) 1985-1988, 1992-1995 Free Software Foundation, Inc.
   Copyright (C) 1996 Ben Wing.

This file is part of XEmacs.

XEmacs 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.

XEmacs 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 XEmacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* Synched up with: Mule 2.0, FSF 19.30. */
/* More syncing: FSF Emacs 19.34.6 by Marc Paquette <marcpa@cam.org> */

#include <config.h>
#include "lisp.h"
#include <limits.h>

#include "buffer.h"
#include "events.h"
#include "frame.h"
#include "insdel.h"
#include "lstream.h"
#include "redisplay.h"
#include "sysdep.h"
#include "window.h"             /* minibuf_level */
#ifdef FILE_CODING
#include "file-coding.h"
#endif

#ifdef HAVE_LIBGEN_H            /* Must come before sysfile.h */
#include <libgen.h>
#endif
#include "sysfile.h"
#include "sysproc.h"
#include "syspwd.h"
#include "systime.h"
#include "sysdir.h"

#ifdef HPUX
#include <netio.h>
#ifdef HPUX_PRE_8_0
#include <errnet.h>
#endif /* HPUX_PRE_8_0 */
#endif /* HPUX */

#ifdef WINDOWSNT
#define NOMINMAX 1
#include <windows.h>
#include <direct.h>
#include <fcntl.h>
#include <stdlib.h>
#endif /* not WINDOWSNT */

#ifdef WINDOWSNT
#define CORRECT_DIR_SEPS(s) \
  do { if ('/' == DIRECTORY_SEP) dostounix_filename (s); \
    else unixtodos_filename (s); \
  } while (0)
#define IS_DRIVE(x) isalpha (x)
/* Need to lower-case the drive letter, or else expanded
   filenames will sometimes compare inequal, because
   `expand-file-name' doesn't always down-case the drive letter.  */
#define DRIVE_LETTER(x) tolower (x)
#endif /* WINDOWSNT */

int lisp_to_time (Lisp_Object, time_t *);
Lisp_Object time_to_lisp (time_t);

/* Nonzero during writing of auto-save files */
static int auto_saving;

/* Set by auto_save_1 to mode of original file so Fwrite_region_internal
   will create a new file with the same mode as the original */
static int auto_save_mode_bits;

/* Alist of elements (REGEXP . HANDLER) for file names
   whose I/O is done with a special handler.  */
Lisp_Object Vfile_name_handler_alist;

/* Format for auto-save files */
Lisp_Object Vauto_save_file_format;

/* Lisp functions for translating file formats */
Lisp_Object Qformat_decode, Qformat_annotate_function;

/* Functions to be called to process text properties in inserted file.  */
Lisp_Object Vafter_insert_file_functions;

/* Functions to be called to create text property annotations for file.  */
Lisp_Object Vwrite_region_annotate_functions;

/* During build_annotations, each time an annotation function is called,
   this holds the annotations made by the previous functions.  */
Lisp_Object Vwrite_region_annotations_so_far;

/* File name in which we write a list of all our auto save files.  */
Lisp_Object Vauto_save_list_file_name;

int disable_auto_save_when_buffer_shrinks;

Lisp_Object Vdirectory_sep_char;

/* These variables describe handlers that have "already" had a chance
   to handle the current operation.

   Vinhibit_file_name_handlers is a list of file name handlers.
   Vinhibit_file_name_operation is the operation being handled.
   If we try to handle that operation, we ignore those handlers.  */

static Lisp_Object Vinhibit_file_name_handlers;
static Lisp_Object Vinhibit_file_name_operation;

Lisp_Object Qfile_error, Qfile_already_exists;

Lisp_Object Qauto_save_hook;
Lisp_Object Qauto_save_error;
Lisp_Object Qauto_saving;

Lisp_Object Qcar_less_than_car;

Lisp_Object Qcompute_buffer_file_truename;

EXFUN (Frunning_temacs_p, 0);

/* signal a file error when errno contains a meaningful value. */

DOESNT_RETURN
report_file_error (CONST char *string, Lisp_Object data)
{
  /* #### dmoore - This uses current_buffer, better make sure no one
     has GC'd the current buffer.  File handlers are giving me a headache
     maybe I'll just always protect current_buffer around all of those
     calls. */

  signal_error (Qfile_error,
                Fcons (build_translated_string (string),
		       Fcons (lisp_strerror (errno), data)));
}

void
maybe_report_file_error (CONST char *string, Lisp_Object data,
			 Lisp_Object class, Error_behavior errb)
{
  /* Optimization: */
  if (ERRB_EQ (errb, ERROR_ME_NOT))
    return;

  maybe_signal_error (Qfile_error,
		      Fcons (build_translated_string (string),
			     Fcons (lisp_strerror (errno), data)),
		      class, errb);
}

/* signal a file error when errno does not contain a meaningful value. */

DOESNT_RETURN
signal_file_error (CONST char *string, Lisp_Object data)
{
  signal_error (Qfile_error,
                list2 (build_translated_string (string), data));
}

void
maybe_signal_file_error (CONST char *string, Lisp_Object data,
			 Lisp_Object class, Error_behavior errb)
{
  /* Optimization: */
  if (ERRB_EQ (errb, ERROR_ME_NOT))
    return;
  maybe_signal_error (Qfile_error,
		      list2 (build_translated_string (string), data),
		      class, errb);
}

DOESNT_RETURN
signal_double_file_error (CONST char *string1, CONST char *string2,
			  Lisp_Object data)
{
  signal_error (Qfile_error,
                list3 (build_translated_string (string1),
		       build_translated_string (string2),
		       data));
}

void
maybe_signal_double_file_error (CONST char *string1, CONST char *string2,
				Lisp_Object data, Lisp_Object class,
				Error_behavior errb)
{
  /* Optimization: */
  if (ERRB_EQ (errb, ERROR_ME_NOT))
    return;
  maybe_signal_error (Qfile_error,
		      list3 (build_translated_string (string1),
			     build_translated_string (string2),
			     data),
		      class, errb);
}

DOESNT_RETURN
signal_double_file_error_2 (CONST char *string1, CONST char *string2,
			    Lisp_Object data1, Lisp_Object data2)
{
  signal_error (Qfile_error,
                list4 (build_translated_string (string1),
		       build_translated_string (string2),
		       data1, data2));
}

void
maybe_signal_double_file_error_2 (CONST char *string1, CONST char *string2,
				  Lisp_Object data1, Lisp_Object data2,
				  Lisp_Object class, Error_behavior errb)
{
  /* Optimization: */
  if (ERRB_EQ (errb, ERROR_ME_NOT))
    return;
  maybe_signal_error (Qfile_error,
		      list4 (build_translated_string (string1),
			     build_translated_string (string2),
			     data1, data2),
		      class, errb);
}


/* Just like strerror(3), except return a lisp string instead of char *.
   The string needs to be converted since it may be localized.
   Perhaps this should use strerror-coding-system instead? */
Lisp_Object
lisp_strerror (int errnum)
{
  return build_ext_string (strerror (errnum), FORMAT_NATIVE);
}

static Lisp_Object
close_file_unwind (Lisp_Object fd)
{
  if (CONSP (fd))
    {
      if (INTP (XCAR (fd)))
	close (XINT (XCAR (fd)));

      free_cons (XCONS (fd));
    }
  else
    close (XINT (fd));

  return Qnil;
}

static Lisp_Object
delete_stream_unwind (Lisp_Object stream)
{
  Lstream_delete (XLSTREAM (stream));
  return Qnil;
}

/* Restore point, having saved it as a marker.  */

static Lisp_Object
restore_point_unwind (Lisp_Object point_marker)
{
  BUF_SET_PT (current_buffer, marker_position (point_marker));
  return Fset_marker (point_marker, Qnil, Qnil);
}

/* Versions of read() and write() that allow quitting out of the actual
   I/O.  We don't use immediate_quit (i.e. direct longjmp() out of the
   signal handler) because that's way too losing.

   (#### Actually, longjmp()ing out of the signal handler may not be
   as losing as I thought.  See sys_do_signal() in sysdep.c.)

   Solaris include files declare the return value as ssize_t.
   Is that standard? */
int
read_allowing_quit (int fildes, void *buf, size_t size)
{
  QUIT;
  return sys_read_1 (fildes, buf, size, 1);
}

int
write_allowing_quit (int fildes, CONST void *buf, size_t size)
{
  QUIT;
  return sys_write_1 (fildes, buf, size, 1);
}


Lisp_Object Qexpand_file_name;
Lisp_Object Qfile_truename;
Lisp_Object Qsubstitute_in_file_name;
Lisp_Object Qdirectory_file_name;
Lisp_Object Qfile_name_directory;
Lisp_Object Qfile_name_nondirectory;
Lisp_Object Qunhandled_file_name_directory;
Lisp_Object Qfile_name_as_directory;
Lisp_Object Qcopy_file;
Lisp_Object Qmake_directory_internal;
Lisp_Object Qdelete_directory;
Lisp_Object Qdelete_file;
Lisp_Object Qrename_file;
Lisp_Object Qadd_name_to_file;
Lisp_Object Qmake_symbolic_link;
Lisp_Object Qfile_exists_p;
Lisp_Object Qfile_executable_p;
Lisp_Object Qfile_readable_p;
Lisp_Object Qfile_symlink_p;
Lisp_Object Qfile_writable_p;
Lisp_Object Qfile_directory_p;
Lisp_Object Qfile_regular_p;
Lisp_Object Qfile_accessible_directory_p;
Lisp_Object Qfile_modes;
Lisp_Object Qset_file_modes;
Lisp_Object Qfile_newer_than_file_p;
Lisp_Object Qinsert_file_contents;
Lisp_Object Qwrite_region;
Lisp_Object Qverify_visited_file_modtime;
Lisp_Object Qset_visited_file_modtime;

/* If FILENAME is handled specially on account of its syntax,
   return its handler function.  Otherwise, return nil.  */

DEFUN ("find-file-name-handler", Ffind_file_name_handler, 1, 2, 0, /*
Return FILENAME's handler function for OPERATION, if it has one.
Otherwise, return nil.
A file name is handled if one of the regular expressions in
`file-name-handler-alist' matches it.

If OPERATION equals `inhibit-file-name-operation', then we ignore
any handlers that are members of `inhibit-file-name-handlers',
but we still do run any other handlers.  This lets handlers
use the standard functions without calling themselves recursively.
*/
       (filename, operation))
{
  /* This function does not GC */
  /* This function can be called during GC */
  /* This function must not munge the match data.  */
  Lisp_Object chain, inhibited_handlers;

  CHECK_STRING (filename);

  if (EQ (operation, Vinhibit_file_name_operation))
    inhibited_handlers = Vinhibit_file_name_handlers;
  else
    inhibited_handlers = Qnil;

  EXTERNAL_LIST_LOOP (chain, Vfile_name_handler_alist)
    {
      Lisp_Object elt = XCAR (chain);
      if (CONSP (elt))
	{
	  Lisp_Object string = XCAR (elt);
	  if (STRINGP (string)
	      && (fast_lisp_string_match (string, filename) >= 0))
	    {
	      Lisp_Object handler = XCDR (elt);
	      if (NILP (Fmemq (handler, inhibited_handlers)))
		return handler;
	    }
	}
      QUIT;
    }
  return Qnil;
}

static Lisp_Object
call2_check_string (Lisp_Object fn, Lisp_Object arg0, Lisp_Object arg1)
{
  /* This function can call lisp */
  Lisp_Object result = call2 (fn, arg0, arg1);
  CHECK_STRING (result);
  return result;
}

static Lisp_Object
call2_check_string_or_nil (Lisp_Object fn, Lisp_Object arg0, Lisp_Object arg1)
{
  /* This function can call lisp */
  Lisp_Object result = call2 (fn, arg0, arg1);
  if (!NILP (result))
    CHECK_STRING (result);
  return result;
}

static Lisp_Object
call3_check_string (Lisp_Object fn, Lisp_Object arg0,
                    Lisp_Object arg1, Lisp_Object arg2)
{
  /* This function can call lisp */
  Lisp_Object result = call3 (fn, arg0, arg1, arg2);
  CHECK_STRING (result);
  return result;
}


DEFUN ("file-name-directory", Ffile_name_directory, 1, 1, 0, /*
Return the directory component in file name NAME.
Return nil if NAME does not include a directory.
Otherwise return a directory spec.
Given a Unix syntax file name, returns a string ending in slash.
*/
       (file))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Bufbyte *beg;
  Bufbyte *p;
  Lisp_Object handler;

  CHECK_STRING (file);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (file, Qfile_name_directory);
  if (!NILP (handler))
    return call2_check_string_or_nil (handler, Qfile_name_directory, file);

#ifdef FILE_SYSTEM_CASE
  file = FILE_SYSTEM_CASE (file);
#endif
  beg = XSTRING_DATA (file);
  p = beg + XSTRING_LENGTH (file);

  while (p != beg && !IS_ANY_SEP (p[-1])
#ifdef WINDOWSNT
	 /* only recognize drive specifier at beginning */
	 && !(p[-1] == ':' && p == beg + 2)
#endif
    ) p--;

  if (p == beg)
    return Qnil;
#ifdef WINDOWSNT
  /* Expansion of "c:" to drive and default directory.  */
  /* (NT does the right thing.)  */
  if (p == beg + 2 && beg[1] == ':')
    {
      /* MAXPATHLEN+1 is guaranteed to be enough space for getdefdir.  */
      Bufbyte *res = alloca (MAXPATHLEN + 1);
      if (getdefdir (toupper (*beg) - 'A' + 1, res))
	{
	  char *c=((char *) res) + strlen ((char *) res);
	  if (!IS_DIRECTORY_SEP (*c))
	    {
	      *c++ = DIRECTORY_SEP;
	      *c = '\0';
	    }
	  beg = res;
	  p = beg + strlen ((char *) beg);
	}
    }
#endif /* WINDOWSNT */
  return make_string (beg, p - beg);
}

DEFUN ("file-name-nondirectory", Ffile_name_nondirectory, 1, 1, 0, /*
Return file name NAME sans its directory.
For example, in a Unix-syntax file name,
this is everything after the last slash,
or the entire name if it contains no slash.
*/
       (file))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Bufbyte *beg, *p, *end;
  Lisp_Object handler;

  CHECK_STRING (file);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (file, Qfile_name_nondirectory);
  if (!NILP (handler))
    return call2_check_string (handler, Qfile_name_nondirectory, file);

  beg = XSTRING_DATA (file);
  end = p = beg + XSTRING_LENGTH (file);

  while (p != beg && !IS_ANY_SEP (p[-1])
#ifdef WINDOWSNT
	 /* only recognize drive specifier at beginning */
	 && !(p[-1] == ':' && p == beg + 2)
#endif
    ) p--;

  return make_string (p, end - p);
}

DEFUN ("unhandled-file-name-directory", Funhandled_file_name_directory, 1, 1, 0, /*
Return a directly usable directory name somehow associated with FILENAME.
A `directly usable' directory name is one that may be used without the
intervention of any file handler.
If FILENAME is a directly usable file itself, return
\(file-name-directory FILENAME).
The `call-process' and `start-process' functions use this function to
get a current directory to run processes in.
*/
  (filename))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Lisp_Object handler;

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

  return Ffile_name_directory (filename);
}


static char *
file_name_as_directory (char *out, char *in)
{
  int size = strlen (in);

  if (size == 0)
    {
      out[0] = '.';
      out[1] = DIRECTORY_SEP;
      out[2] = '\0';
    }
  else
    {
      strcpy (out, in);
      /* Append a slash if necessary */
      if (!IS_ANY_SEP (out[size-1]))
	{
	  out[size] = DIRECTORY_SEP;
	  out[size + 1] = '\0';
	}
    }
  return out;
}

DEFUN ("file-name-as-directory", Ffile_name_as_directory, 1, 1, 0, /*
Return a string representing file FILENAME interpreted as a directory.
This operation exists because a directory is also a file, but its name as
a directory is different from its name as a file.
The result can be used as the value of `default-directory'
or passed as second argument to `expand-file-name'.
For a Unix-syntax file name, just appends a slash,
except for (file-name-as-directory \"\") => \"./\".
*/
       (file))
{
  /* This function can GC.  GC checked 1997.04.06. */
  char *buf;
  Lisp_Object handler;

  CHECK_STRING (file);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (file, Qfile_name_as_directory);
  if (!NILP (handler))
    return call2_check_string (handler, Qfile_name_as_directory, file);

  buf = (char *) alloca (XSTRING_LENGTH (file) + 10);
  return build_string (file_name_as_directory
		       (buf, (char *) XSTRING_DATA (file)));
}

/*
 * Convert from directory name to filename.
 * On UNIX, it's simple: just make sure there isn't a terminating /
 *
 * Value is nonzero if the string output is different from the input.
 */

static int
directory_file_name (CONST char *src, char *dst)
{
  long slen;

  slen = strlen (src);
  /* Process as Unix format: just remove any final slash.
     But leave "/" unchanged; do not change it to "".  */
  strcpy (dst, src);
#ifdef APOLLO
  /* Handle // as root for apollo's.  */
  if ((slen > 2 && dst[slen - 1] == '/')
      || (slen > 1 && dst[0] != '/' && dst[slen - 1] == '/'))
    dst[slen - 1] = 0;
#else
  if (slen > 1
      && IS_DIRECTORY_SEP (dst[slen - 1])
#ifdef WINDOWSNT
      && !IS_ANY_SEP (dst[slen - 2])
#endif /* WINDOWSNT */
      )
    dst[slen - 1] = 0;
#endif /* APOLLO */
  return 1;
}

DEFUN ("directory-file-name", Fdirectory_file_name, 1, 1, 0, /*
Return the file name of the directory named DIR.
This is the name of the file that holds the data for the directory DIR.
This operation exists because a directory is also a file, but its name as
a directory is different from its name as a file.
In Unix-syntax, this function just removes the final slash.
*/
       (directory))
{
  /* This function can GC.  GC checked 1997.04.06. */
  char *buf;
  Lisp_Object handler;

  CHECK_STRING (directory);

#if 0 /* #### WTF? */
  if (NILP (directory))
    return Qnil;
#endif

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (directory, Qdirectory_file_name);
  if (!NILP (handler))
    return call2_check_string (handler, Qdirectory_file_name, directory);
  buf = (char *) alloca (XSTRING_LENGTH (directory) + 20);
  directory_file_name ((char *) XSTRING_DATA (directory), buf);
  return build_string (buf);
}

/* Fmake_temp_name used to be a simple wrapper around mktemp(), but it
   proved too broken for our purposes (it supported only 26 or 62
   unique names under some implementations).  For example, this
   arbitrary limit broke generation of Gnus Incoming* files.

   This implementation is better than what one usually finds in libc.
   --hniksic */

DEFUN ("make-temp-name", Fmake_temp_name, 1, 1, 0, /*
Generate temporary file name starting with PREFIX.
The Emacs process number forms part of the result, so there is no
danger of generating a name being used by another process.

In addition, this function makes an attempt to choose a name that
does not specify an existing file.  To make this work, PREFIX should
be an absolute file name.
*/
       (prefix))
{
  static char tbl[64] = {
    'A','B','C','D','E','F','G','H',
    'I','J','K','L','M','N','O','P',
    'Q','R','S','T','U','V','W','X',
    'Y','Z','a','b','c','d','e','f',
    'g','h','i','j','k','l','m','n',
    'o','p','q','r','s','t','u','v',
    'w','x','y','z','0','1','2','3',
    '4','5','6','7','8','9','-','_' };
  static unsigned count, count_initialized_p;

  Lisp_Object val;
  Bytecount len;
  Bufbyte *p, *data;
  unsigned pid;

  CHECK_STRING (prefix);

  /* I was tempted to apply Fexpand_file_name on PREFIX here, but it's
     a bad idea because:

     1) It might change the prefix, so the resulting string might not
     begin with PREFIX.  This violates the principle of least
     surprise.

     2) It breaks under many unforeseeable circumstances, such as with
     the code that uses (make-temp-name "") instead of
     (make-temp-name "./").

     3) It might yield unexpected (to stat(2)) results in the presence
     of EFS and file name handlers.  */

  len = XSTRING_LENGTH (prefix);
  val = make_uninit_string (len + 6);
  data = XSTRING_DATA (val);
  memcpy (data, XSTRING_DATA (prefix), len);
  p = data + len;

  /* VAL is created by adding 6 characters to PREFIX.  The first three
     are the PID of this process, in base 64, and the second three are
     incremented if the file already exists.  This ensures 262144
     unique file names per PID per PREFIX.  */

  pid = (unsigned)getpid ();
  *p++ = tbl[pid & 63], pid >>= 6;
  *p++ = tbl[pid & 63], pid >>= 6;
  *p++ = tbl[pid & 63], pid >>= 6;

  /* Here we try to minimize useless stat'ing when this function is
     invoked many times successively with the same PREFIX.  We achieve
     this by initializing count to a random value, and incrementing it
     afterwards.  */
  if (!count_initialized_p)
    {
      count = (unsigned)time (NULL);
      /* Dumping temacs with a non-zero count_initialized_p wouldn't
         make much sense.  */
      if (NILP (Frunning_temacs_p ()))
	count_initialized_p = 1;
    }

  while (1)
    {
      struct stat ignored;
      unsigned num = count;

      p[0] = tbl[num & 63], num >>= 6;
      p[1] = tbl[num & 63], num >>= 6;
      p[2] = tbl[num & 63], num >>= 6;

      /* Poor man's congruential RN generator.  Replace with ++count
         for debugging.  */
      count += 25229;
      count %= 225307;

      QUIT;

      if (stat ((CONST char *) data, &ignored) < 0)
	{
	  /* We want to return only if errno is ENOENT.  */
	  if (errno == ENOENT)
	    return val;

	  /* The error here is dubious, but there is little else we
	     can do.  The alternatives are to return nil, which is
	     as bad as (and in many cases worse than) throwing the
	     error, or to ignore the error, which will likely result
	     in inflooping.  */
	  report_file_error ("Cannot create temporary name for prefix",
			     list1 (prefix));
	  return Qnil; /* not reached */
	}
    }
}


DEFUN ("expand-file-name", Fexpand_file_name, 1, 2, 0, /*
Convert filename NAME to absolute, and canonicalize it.
Second arg DEFAULT-DIRECTORY is directory to start with if NAME is relative
 (does not start with slash); if DEFAULT-DIRECTORY is nil or missing,
the current buffer's value of default-directory is used.
File name components that are `.' are removed, and
so are file name components followed by `..', along with the `..' itself;
note that these simplifications are done without checking the resulting
file names in the file system.
An initial `~/' expands to your home directory.
An initial `~USER/' expands to USER's home directory.
See also the function `substitute-in-file-name'.
*/
       (name, default_directory))
{
  /* This function can GC */
  Bufbyte *nm;

  Bufbyte *newdir, *p, *o;
  int tlen;
  Bufbyte *target;
#ifdef WINDOWSNT
  int drive = 0;
  int collapse_newdir = 1;
#else
  struct passwd *pw;
#endif /* WINDOWSNT */
  int length;
  Lisp_Object handler;
#ifdef __CYGWIN32__
  char *user;
#endif

  CHECK_STRING (name);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (name, Qexpand_file_name);
  if (!NILP (handler))
    return call3_check_string (handler, Qexpand_file_name, name,
			       default_directory);

  /* Use the buffer's default-directory if DEFAULT_DIRECTORY is omitted.  */
  if (NILP (default_directory))
    default_directory = current_buffer->directory;
  if (! STRINGP (default_directory))
    default_directory = build_string ("/");

  if (!NILP (default_directory))
    {
      handler = Ffind_file_name_handler (default_directory, Qexpand_file_name);
      if (!NILP (handler))
	return call3 (handler, Qexpand_file_name, name, default_directory);
    }

  o = XSTRING_DATA (default_directory);

  /* Make sure DEFAULT_DIRECTORY is properly expanded.
     It would be better to do this down below where we actually use
     default_directory.  Unfortunately, calling Fexpand_file_name recursively
     could invoke GC, and the strings might be relocated.  This would
     be annoying because we have pointers into strings lying around
     that would need adjusting, and people would add new pointers to
     the code and forget to adjust them, resulting in intermittent bugs.
     Putting this call here avoids all that crud.

     The EQ test avoids infinite recursion.  */
  if (! NILP (default_directory) && !EQ (default_directory, name)
      /* Save time in some common cases - as long as default_directory
	 is not relative, it can be canonicalized with name below (if it
	 is needed at all) without requiring it to be expanded now.  */
#ifdef WINDOWSNT
      /* Detect MSDOS file names with drive specifiers.  */
      && ! (IS_DRIVE (o[0]) && (IS_DEVICE_SEP (o[1]) && IS_DIRECTORY_SEP (o[2])))
      /* Detect Windows file names in UNC format.  */
      && ! (IS_DIRECTORY_SEP (o[0]) && IS_DIRECTORY_SEP (o[1]))

#else /* not WINDOWSNT */

      /* Detect Unix absolute file names (/... alone is not absolute on
	 DOS or Windows).  */
      && ! (IS_DIRECTORY_SEP (o[0]))
#endif /* not WINDOWSNT */
      )
    {
      struct gcpro gcpro1;

      GCPRO1 (name);
      default_directory = Fexpand_file_name (default_directory, Qnil);
      UNGCPRO;
    }

#ifdef FILE_SYSTEM_CASE
  name = FILE_SYSTEM_CASE (name);
#endif

 /* #### dmoore - this is ugly, clean this up.  Looks like nm pointing
    into name should be safe during all of this, though. */
  nm = XSTRING_DATA (name);

#ifdef WINDOWSNT
  /* We will force directory separators to be either all \ or /, so make
     a local copy to modify, even if there ends up being no change. */
  nm = strcpy (alloca (strlen (nm) + 1), nm);

  /* Find and remove drive specifier if present; this makes nm absolute
     even if the rest of the name appears to be relative. */
  {
    Bufbyte *colon = strrchr (nm, ':');

    if (colon)
      /* Only recognize colon as part of drive specifier if there is a
	 single alphabetic character preceding the colon (and if the
	 character before the drive letter, if present, is a directory
	 separator); this is to support the remote system syntax used by
	 ange-ftp, and the "po:username" syntax for POP mailboxes. */
    look_again:
      if (nm == colon)
	nm++;
      else if (IS_DRIVE (colon[-1])
	       && (colon == nm + 1 || IS_DIRECTORY_SEP (colon[-2])))
	{
	  drive = colon[-1];
	  nm = colon + 1;
	}
      else
	{
	  while (--colon >= nm)
	    if (colon[0] == ':')
	      goto look_again;
	}
  }

  /* If we see "c://somedir", we want to strip the first slash after the
     colon when stripping the drive letter.  Otherwise, this expands to
     "//somedir".  */
  if (drive && IS_DIRECTORY_SEP (nm[0]) && IS_DIRECTORY_SEP (nm[1]))
    nm++;
#endif /* WINDOWSNT */

  /* If nm is absolute, look for /./ or /../ sequences; if none are
     found, we can probably return right away.  We will avoid allocating
     a new string if name is already fully expanded.  */
  if (
      IS_DIRECTORY_SEP (nm[0])
#ifdef WINDOWSNT
      && (drive || IS_DIRECTORY_SEP (nm[1]))
#endif
      )
    {
      /* If it turns out that the filename we want to return is just a
	 suffix of FILENAME, we don't need to go through and edit
	 things; we just need to construct a new string using data
	 starting at the middle of FILENAME.  If we set lose to a
	 non-zero value, that means we've discovered that we can't do
	 that cool trick.  */
      int lose = 0;

      p = nm;
      while (*p)
	{
	  /* Since we know the name is absolute, we can assume that each
	     element starts with a "/".  */

	  /* "." and ".." are hairy.  */
	  if (IS_DIRECTORY_SEP (p[0])
	      && p[1] == '.'
	      && (IS_DIRECTORY_SEP (p[2])
		  || p[2] == 0
		  || (p[2] == '.' && (IS_DIRECTORY_SEP (p[3])
				      || p[3] == 0))))
	    lose = 1;
	  p++;
	}
      if (!lose)
	{
#ifdef WINDOWSNT
	  /* Make sure directories are all separated with / or \ as
	     desired, but avoid allocation of a new string when not
	     required. */
	  CORRECT_DIR_SEPS (nm);
	  if (IS_DIRECTORY_SEP (nm[1]))
	    {
	      if (strcmp (nm, XSTRING_DATA (name)) != 0)
		name = build_string (nm);
	    }
	  /* drive must be set, so this is okay */
	  else if (strcmp (nm - 2, XSTRING_DATA (name)) != 0)
	    {
	      name = make_string (nm - 2, p - nm + 2);
	      XSTRING_DATA (name)[0] = DRIVE_LETTER (drive);
	      XSTRING_DATA (name)[1] = ':';
	    }
	  return name;
#else /* not WINDOWSNT */
	  if (nm == XSTRING_DATA (name))
	    return name;
	  return build_string ((char *) nm);
#endif /* not WINDOWSNT */
	}
    }

  /* At this point, nm might or might not be an absolute file name.  We
     need to expand ~ or ~user if present, otherwise prefix nm with
     default_directory if nm is not absolute, and finally collapse /./
     and /foo/../ sequences.

     We set newdir to be the appropriate prefix if one is needed:
       - the relevant user directory if nm starts with ~ or ~user
       - the specified drive's working dir (DOS/NT only) if nm does not
         start with /
       - the value of default_directory.

     Note that these prefixes are not guaranteed to be absolute (except
     for the working dir of a drive).  Therefore, to ensure we always
     return an absolute name, if the final prefix is not absolute we
     append it to the current working directory.  */

  newdir = 0;

  if (nm[0] == '~')		/* prefix ~ */
    {
      if (IS_DIRECTORY_SEP (nm[1])
	  || nm[1] == 0)	/* ~ by itself */
	{
	  char * newdir_external = get_home_directory ();

	  if (newdir_external == NULL)
	    newdir = (Bufbyte *) "";
	  else
	    GET_C_CHARPTR_INT_FILENAME_DATA_ALLOCA (newdir_external, newdir);

	  nm++;
#ifdef WINDOWSNT
	  collapse_newdir = 0;
#endif
	}
      else			/* ~user/filename */
	{
	  for (p = nm; *p && (!IS_DIRECTORY_SEP (*p)); p++)
	    DO_NOTHING;
	  o = (Bufbyte *) alloca (p - nm + 1);
	  memcpy (o, (char *) nm, p - nm);
	  o [p - nm] = 0;

	  /* #### marcpa's syncing note: FSF uses getpwnam even on NT,
	     which does not work.  The following works only if ~USER
	     names the user who runs this instance of XEmacs.  While
	     NT is single-user (for the moment) you still can have
	     multiple user profiles users defined, each with its HOME.
	     Therefore, the following should be reworked to handle
	     this case.  */
#ifdef  WINDOWSNT
	  /* Now if the file given is "~foo/file" and HOME="c:/", then
	     we want the file to be named "c:/file" ("~foo" becomes
	     "c:/").  The variable o has "~foo", so we can use the
	     length of that string to offset nm.  August Hill, 31 Aug
	     1998.  */
	  newdir = (Bufbyte *) get_home_directory();
	  dostounix_filename (newdir);
	  nm += strlen(o) + 1;
#else  /* not WINDOWSNT */
#ifdef __CYGWIN32__
	  if ((user = user_login_name (NULL)) != NULL)
	    {
	      /* Does the user login name match the ~name? */
	      if (strcmp(user,((char *) o + 1)) == 0)
	        {
		  newdir = (Bufbyte *)  get_home_directory();
	          nm = p;
		}
	    }
          if (! newdir)
            {
#endif /* __CYGWIN32__ */
	  /* Jamie reports that getpwnam() can get wedged by SIGIO/SIGALARM
	     occurring in it. (It can call select()). */
	  slow_down_interrupts ();
	  pw = (struct passwd *) getpwnam ((char *) o + 1);
	  speed_up_interrupts ();
	  if (pw)
	    {
	      newdir = (Bufbyte *) pw -> pw_dir;
	      nm = p;
	    }
#ifdef __CYGWIN32__
	    }
#endif
#endif /* not WINDOWSNT */

	  /* If we don't find a user of that name, leave the name
	     unchanged; don't move nm forward to p.  */
	}
    }

#ifdef WINDOWSNT
  /* On DOS and Windows, nm is absolute if a drive name was specified;
     use the drive's current directory as the prefix if needed.  */
  if (!newdir && drive)
    {
      /* Get default directory if needed to make nm absolute. */
      if (!IS_DIRECTORY_SEP (nm[0]))
	{
	  newdir = alloca (MAXPATHLEN + 1);
	  if (!getdefdir (toupper (drive) - 'A' + 1, newdir))
	    newdir = NULL;
	}
      if (!newdir)
	{
	  /* Either nm starts with /, or drive isn't mounted. */
	  newdir = alloca (4);
	  newdir[0] = DRIVE_LETTER (drive);
	  newdir[1] = ':';
	  newdir[2] = '/';
	  newdir[3] = 0;
	}
    }
#endif /* WINDOWSNT */

  /* Finally, if no prefix has been specified and nm is not absolute,
     then it must be expanded relative to default_directory. */

  if (1
#ifndef WINDOWSNT
      /* /... alone is not absolute on DOS and Windows. */
      && !IS_DIRECTORY_SEP (nm[0])
#else
      && !(IS_DIRECTORY_SEP (nm[0]) && IS_DIRECTORY_SEP (nm[1]))
#endif
      && !newdir)
    {
      newdir = XSTRING_DATA (default_directory);
    }

#ifdef WINDOWSNT
  if (newdir)
    {
      /* First ensure newdir is an absolute name. */
      if (
	  /* Detect MSDOS file names with drive specifiers.  */
	  ! (IS_DRIVE (newdir[0])
	     && IS_DEVICE_SEP (newdir[1]) && IS_DIRECTORY_SEP (newdir[2]))
	  /* Detect Windows file names in UNC format.  */
	  && ! (IS_DIRECTORY_SEP (newdir[0]) && IS_DIRECTORY_SEP (newdir[1]))
	  /* Detect drive spec by itself */
	  && ! (IS_DEVICE_SEP (newdir[1]) && newdir[2] == 0)
	  )
	{
	  /* Effectively, let newdir be (expand-file-name newdir cwd).
	     Because of the admonition against calling expand-file-name
	     when we have pointers into lisp strings, we accomplish this
	     indirectly by prepending newdir to nm if necessary, and using
	     cwd (or the wd of newdir's drive) as the new newdir. */

	  if (IS_DRIVE (newdir[0]) && newdir[1] == ':')
	    {
	      drive = newdir[0];
	      newdir += 2;
	    }
	  if (!IS_DIRECTORY_SEP (nm[0]))
	    {
	      char * tmp = alloca (strlen (newdir) + strlen (nm) + 2);
	      file_name_as_directory (tmp, newdir);
	      strcat (tmp, nm);
	      nm = tmp;
	    }
	  newdir = alloca (MAXPATHLEN + 1);
	  if (drive)
	    {
	      if (!getdefdir (toupper (drive) - 'A' + 1, newdir))
		newdir = "/";
	    }
	  else
	    getwd (newdir);
	}

      /* Strip off drive name from prefix, if present. */
      if (IS_DRIVE (newdir[0]) && newdir[1] == ':')
	{
	  drive = newdir[0];
	  newdir += 2;
	}

      /* Keep only a prefix from newdir if nm starts with slash
         (/ /server/share for UNC, nothing otherwise).  */
      if (IS_DIRECTORY_SEP (nm[0]) && collapse_newdir)
	{
	  if (IS_DIRECTORY_SEP (newdir[0]) && IS_DIRECTORY_SEP (newdir[1]))
	    {
	      newdir = strcpy (alloca (strlen (newdir) + 1), newdir);
	      p = newdir + 2;
	      while (*p && !IS_DIRECTORY_SEP (*p)) p++;
	      p++;
	      while (*p && !IS_DIRECTORY_SEP (*p)) p++;
	      *p = 0;
	    }
	  else
	    newdir = "";
	}
    }
#endif /* WINDOWSNT */

  if (newdir)
    {
      /* Get rid of any slash at the end of newdir, unless newdir is
	 just // (an incomplete UNC name).  */
      length = strlen ((char *) newdir);
      if (length > 1 && IS_DIRECTORY_SEP (newdir[length - 1])
#ifdef WINDOWSNT
	  && !(length == 2 && IS_DIRECTORY_SEP (newdir[0]))
#endif
	  )
	{
	  Bufbyte *temp = (Bufbyte *) alloca (length);
	  memcpy (temp, newdir, length - 1);
	  temp[length - 1] = 0;
	  newdir = temp;
	}
      tlen = length + 1;
    }
  else
    tlen = 0;

  /* Now concatenate the directory and name to new space in the stack frame */
  tlen += strlen ((char *) nm) + 1;
#ifdef WINDOWSNT
  /* Add reserved space for drive name.  (The Microsoft x86 compiler
     produces incorrect code if the following two lines are combined.)  */
  target = (Bufbyte *) alloca (tlen + 2);
  target += 2;
#else  /* not WINDOWSNT */
  target = (Bufbyte *) alloca (tlen);
#endif /* not WINDOWSNT */
  *target = 0;

  if (newdir)
    {
      if (nm[0] == 0 || IS_DIRECTORY_SEP (nm[0]))
	strcpy ((char *) target, (char *) newdir);
      else
	file_name_as_directory ((char *) target, (char *) newdir);
    }

  strcat ((char *) target, (char *) nm);

  /* ASSERT (IS_DIRECTORY_SEP (target[0])) if not VMS */

  /* Now canonicalize by removing /. and /foo/.. if they appear.  */

  p = target;
  o = target;

  while (*p)
    {
      if (!IS_DIRECTORY_SEP (*p))
	{
	  *o++ = *p++;
	}
      else if (IS_DIRECTORY_SEP (p[0])
	       && p[1] == '.'
	       && (IS_DIRECTORY_SEP (p[2])
		   || p[2] == 0))
	{
	  /* If "/." is the entire filename, keep the "/".  Otherwise,
	     just delete the whole "/.".  */
	  if (o == target && p[2] == '\0')
	    *o++ = *p;
	  p += 2;
	}
      else if (IS_DIRECTORY_SEP (p[0]) && p[1] == '.' && p[2] == '.'
	       /* `/../' is the "superroot" on certain file systems.  */
	       && o != target
	       && (IS_DIRECTORY_SEP (p[3]) || p[3] == 0))
	{
	  while (o != target && (--o) && !IS_DIRECTORY_SEP (*o))
	    ;
	  /* Keep initial / only if this is the whole name.  */
	  if (o == target && IS_ANY_SEP (*o) && p[3] == 0)
	    ++o;
	  p += 3;
	}
#ifdef WINDOWSNT
      /* if drive is set, we're not dealing with an UNC, so
	 multiple dir-seps are redundant (and reportedly cause trouble
	 under win95) */
      else if (drive && IS_DIRECTORY_SEP (p[0]) && IS_DIRECTORY_SEP (p[1]))
	  ++p;
#endif
      else
	{
	  *o++ = *p++;
	}
    }

#ifdef WINDOWSNT
  /* At last, set drive name, except for network file name.  */
  if (drive)
    {
      target -= 2;
      target[0] = DRIVE_LETTER (drive);
      target[1] = ':';
    }
  else
    {
      assert (IS_DIRECTORY_SEP (target[0]) && IS_DIRECTORY_SEP (target[1]));
    }
  CORRECT_DIR_SEPS (target);
#endif /* WINDOWSNT */

  return make_string (target, o - target);
}

#if 0 /* FSFmacs */
/* another older version of expand-file-name; */
#endif

DEFUN ("file-truename", Ffile_truename, 1, 2, 0, /*
Return the canonical name of the given FILE.
Second arg DEFAULT is directory to start with if FILE is relative
 (does not start with slash); if DEFAULT is nil or missing,
 the current buffer's value of default-directory is used.
No component of the resulting pathname will be a symbolic link, as
 in the realpath() function.
*/
       (filename, default_))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Lisp_Object expanded_name;
  Lisp_Object handler;
  struct gcpro gcpro1;

  CHECK_STRING (filename);

  expanded_name = Fexpand_file_name (filename, default_);

  if (!STRINGP (expanded_name))
    return Qnil;

  GCPRO1 (expanded_name);
  handler = Ffind_file_name_handler (expanded_name, Qfile_truename);
  UNGCPRO;

  if (!NILP (handler))
    return call2_check_string (handler, Qfile_truename, expanded_name);

  {
    char resolved_path[MAXPATHLEN];
    Extbyte *path;
    Extbyte *p;
    Extcount elen = XSTRING_LENGTH (expanded_name);

    GET_STRING_FILENAME_DATA_ALLOCA (expanded_name,path,elen);
    p = path;
    if (elen > MAXPATHLEN)
      goto toolong;
    
    /* Try doing it all at once. */
    /* !! Does realpath() Mule-encapsulate?
       Answer: Nope! So we do it above */
    if (!xrealpath ((char *) path, resolved_path))
      {
	/* Didn't resolve it -- have to do it one component at a time. */
	/* "realpath" is a typically useless, stupid un*x piece of crap.
	   It claims to return a useful value in the "error" case, but since
	   there is no indication provided of how far along the pathname
	   the function went before erring, there is no way to use the
	   partial result returned.  What a piece of junk. */
	for (;;)
	  {
	    p = (Extbyte *) memchr (p + 1, '/', elen - (p + 1 - path));
	    if (p)
	      *p = 0;

	    /* memset (resolved_path, 0, sizeof (resolved_path)); */
	    if (xrealpath ((char *) path, resolved_path))
	      {
		if (p)
		  *p = '/';
		else
		  break;

	      }
	    else if (errno == ENOENT || errno == EACCES)
	      {
		/* Failed on this component.  Just tack on the rest of
		   the string and we are done. */
		int rlen = strlen (resolved_path);

		/* "On failure, it returns NULL, sets errno to indicate
		   the error, and places in resolved_path the absolute pathname
		   of the path component which could not be resolved." */
		if (p)
		  {
		    int plen = elen - (p - path);

		    if (rlen > 1 && resolved_path[rlen - 1] == '/')
		      rlen = rlen - 1;

		    if (plen + rlen + 1 > countof (resolved_path))
		      goto toolong;

		    resolved_path[rlen] = '/';
		    memcpy (resolved_path + rlen + 1, p + 1, plen + 1 - 1);
		  }
		break;
	      }
	    else
	      goto lose;
	  }
      }

    {
      int rlen = strlen (resolved_path);
      if (elen > 0 && XSTRING_BYTE (expanded_name, elen - 1) == '/'
          && !(rlen > 0 && resolved_path[rlen - 1] == '/'))
	{
	  if (rlen + 1 > countof (resolved_path))
	    goto toolong;
	  resolved_path[rlen] = '/';
	  resolved_path[rlen + 1] = 0;
	  rlen = rlen + 1;
	}
      return make_ext_string ((Bufbyte *) resolved_path, rlen, FORMAT_BINARY);
    }

  toolong:
    errno = ENAMETOOLONG;
    goto lose;
  lose:
    report_file_error ("Finding truename", list1 (expanded_name));
  }
  return Qnil;	/* suppress compiler warning */
}


DEFUN ("substitute-in-file-name", Fsubstitute_in_file_name, 1, 1, 0, /*
Substitute environment variables referred to in FILENAME.
`$FOO' where FOO is an environment variable name means to substitute
the value of that variable.  The variable name should be terminated
with a character not a letter, digit or underscore; otherwise, enclose
the entire variable name in braces.
If `/~' appears, all of FILENAME through that `/' is discarded.

*/
       (string))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Bufbyte *nm;

  Bufbyte *s, *p, *o, *x, *endp;
  Bufbyte *target = 0;
  int total = 0;
  int substituted = 0;
  Bufbyte *xnm;
  Lisp_Object handler;

  CHECK_STRING (string);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (string, Qsubstitute_in_file_name);
  if (!NILP (handler))
    return call2_check_string_or_nil (handler, Qsubstitute_in_file_name,
				      string);

  nm = XSTRING_DATA (string);
  endp = nm + XSTRING_LENGTH (string);

  /* If /~ or // appears, discard everything through first slash. */

  for (p = nm; p != endp; p++)
    {
      if ((p[0] == '~'
#if defined (APOLLO) || defined (WINDOWSNT) || defined (__CYGWIN32__)
	   /* // at start of file name is meaningful in Apollo and
	      WindowsNT systems */
	   || (IS_DIRECTORY_SEP (p[0]) && p - 1 != nm)
#else /* not (APOLLO || WINDOWSNT || __CYGWIN32__) */
	   || IS_DIRECTORY_SEP (p[0])
#endif /* not (APOLLO || WINDOWSNT || __CYGWIN32__) */
	   )
	  && p != nm
	  && (IS_DIRECTORY_SEP (p[-1])))
	{
	  nm = p;
	  substituted = 1;
	}
#ifdef WINDOWSNT
      /* see comment in expand-file-name about drive specifiers */
      else if (IS_DRIVE (p[0]) && p[1] == ':'
	       && p > nm && IS_DIRECTORY_SEP (p[-1]))
	{
	  nm = p;
	  substituted = 1;
	}
#endif /* WINDOWSNT */
    }

  /* See if any variables are substituted into the string
     and find the total length of their values in `total' */

  for (p = nm; p != endp;)
    if (*p != '$')
      p++;
    else
      {
	p++;
	if (p == endp)
	  goto badsubst;
	else if (*p == '$')
	  {
	    /* "$$" means a single "$" */
	    p++;
	    total -= 1;
	    substituted = 1;
	    continue;
	  }
	else if (*p == '{')
	  {
	    o = ++p;
	    while (p != endp && *p != '}') p++;
	    if (*p != '}') goto missingclose;
	    s = p;
	  }
	else
	  {
	    o = p;
	    while (p != endp && (isalnum (*p) || *p == '_')) p++;
	    s = p;
	  }

	/* Copy out the variable name */
	target = (Bufbyte *) alloca (s - o + 1);
	strncpy ((char *) target, (char *) o, s - o);
	target[s - o] = 0;
#ifdef WINDOWSNT
	strupr (target); /* $home == $HOME etc.  */
#endif /* WINDOWSNT */

	/* Get variable value */
	o = (Bufbyte *) egetenv ((char *) target);
	if (!o) goto badvar;
	total += strlen ((char *) o);
	substituted = 1;
      }

  if (!substituted)
    return string;

  /* If substitution required, recopy the string and do it */
  /* Make space in stack frame for the new copy */
  xnm = (Bufbyte *) alloca (XSTRING_LENGTH (string) + total + 1);
  x = xnm;

  /* Copy the rest of the name through, replacing $ constructs with values */
  for (p = nm; *p;)
    if (*p != '$')
      *x++ = *p++;
    else
      {
	p++;
	if (p == endp)
	  goto badsubst;
	else if (*p == '$')
	  {
	    *x++ = *p++;
	    continue;
	  }
	else if (*p == '{')
	  {
	    o = ++p;
	    while (p != endp && *p != '}') p++;
	    if (*p != '}') goto missingclose;
	    s = p++;
	  }
	else
	  {
	    o = p;
	    while (p != endp && (isalnum (*p) || *p == '_')) p++;
	    s = p;
	  }

	/* Copy out the variable name */
	target = (Bufbyte *) alloca (s - o + 1);
	strncpy ((char *) target, (char *) o, s - o);
	target[s - o] = 0;
#ifdef WINDOWSNT
	strupr (target); /* $home == $HOME etc.  */
#endif /* WINDOWSNT */

	/* Get variable value */
	o = (Bufbyte *) egetenv ((char *) target);
	if (!o)
	  goto badvar;

	strcpy ((char *) x, (char *) o);
	x += strlen ((char *) o);
      }

  *x = 0;

  /* If /~ or // appears, discard everything through first slash. */

  for (p = xnm; p != x; p++)
    if ((p[0] == '~'
#if defined (APOLLO) || defined (WINDOWSNT)
	 || (IS_DIRECTORY_SEP (p[0]) && p - 1 != xnm)
#else /* not (APOLLO || WINDOWSNT) */
	 || IS_DIRECTORY_SEP (p[0])
#endif /* APOLLO || WINDOWSNT */
	 )
	/* don't do p[-1] if that would go off the beginning --jwz */
	&& p != nm && p > xnm && IS_DIRECTORY_SEP (p[-1]))
      xnm = p;
#ifdef WINDOWSNT
    else if (IS_DRIVE (p[0]) && p[1] == ':'
	     && p > nm && IS_DIRECTORY_SEP (p[-1]))
	xnm = p;
#endif

  return make_string (xnm, x - xnm);

 badsubst:
  error ("Bad format environment-variable substitution");
 missingclose:
  error ("Missing \"}\" in environment-variable substitution");
 badvar:
  error ("Substituting nonexistent environment variable \"%s\"",
	 target);

  /* NOTREACHED */
  return Qnil;	/* suppress compiler warning */
}

/* A slightly faster and more convenient way to get
   (directory-file-name (expand-file-name FOO)).  */

Lisp_Object
expand_and_dir_to_file (Lisp_Object filename, Lisp_Object defdir)
{
  /* This function can call lisp */
  Lisp_Object abspath;
  struct gcpro gcpro1;

  abspath = Fexpand_file_name (filename, defdir);
  GCPRO1 (abspath);
  /* Remove final slash, if any (unless path is root).
     stat behaves differently depending!  */
  if (XSTRING_LENGTH (abspath) > 1
      && IS_DIRECTORY_SEP (XSTRING_BYTE (abspath, XSTRING_LENGTH (abspath) - 1))
      && !IS_DEVICE_SEP (XSTRING_BYTE (abspath, XSTRING_LENGTH (abspath) - 2)))
    /* We cannot take shortcuts; they might be wrong for magic file names.  */
    abspath = Fdirectory_file_name (abspath);
  UNGCPRO;
  return abspath;
}

/* Signal an error if the file ABSNAME already exists.
   If INTERACTIVE is nonzero, ask the user whether to proceed,
   and bypass the error if the user says to go ahead.
   QUERYSTRING is a name for the action that is being considered
   to alter the file.
   *STATPTR is used to store the stat information if the file exists.
   If the file does not exist, STATPTR->st_mode is set to 0.  */

static void
barf_or_query_if_file_exists (Lisp_Object absname, CONST char *querystring,
			      int interactive, struct stat *statptr)
{
  /* This function can GC.  GC checked 1997.04.06. */
  struct stat statbuf;

  /* stat is a good way to tell whether the file exists,
     regardless of what access permissions it has.  */
  if (stat ((char *) XSTRING_DATA (absname), &statbuf) >= 0)
    {
      Lisp_Object tem;

      if (interactive)
	{
	  Lisp_Object prompt;
	  struct gcpro gcpro1;

	  prompt = emacs_doprnt_string_c
	    ((CONST Bufbyte *) GETTEXT ("File %s already exists; %s anyway? "),
	     Qnil, -1, XSTRING_DATA (absname),
	     GETTEXT (querystring));

	  GCPRO1 (prompt);
	  tem = call1 (Qyes_or_no_p, prompt);
	  UNGCPRO;
	}
      else
        tem = Qnil;

      if (NILP (tem))
	Fsignal (Qfile_already_exists,
		 list2 (build_translated_string ("File already exists"),
			absname));
      if (statptr)
	*statptr = statbuf;
    }
  else
    {
      if (statptr)
	statptr->st_mode = 0;
    }
  return;
}

DEFUN ("copy-file", Fcopy_file, 2, 4,
       "fCopy file: \nFCopy %s to file: \np\nP", /*
Copy FILE to NEWNAME.  Both args must be strings.
Signals a `file-already-exists' error if file NEWNAME already exists,
unless a third argument OK-IF-ALREADY-EXISTS is supplied and non-nil.
A number as third arg means request confirmation if NEWNAME already exists.
This is what happens in interactive use with M-x.
Fourth arg KEEP-TIME non-nil means give the new file the same
last-modified time as the old one.  (This works on only some systems.)
A prefix arg makes KEEP-TIME non-nil.
*/
       (filename, newname, ok_if_already_exists, keep_time))
{
  /* This function can GC.  GC checked 1997.04.06. */
  int ifd, ofd, n;
  char buf[16 * 1024];
  struct stat st, out_st;
  Lisp_Object handler;
  int speccount = specpdl_depth ();
  struct gcpro gcpro1, gcpro2;
  /* Lisp_Object args[6]; */
  int input_file_statable_p;

  GCPRO2 (filename, newname);
  CHECK_STRING (filename);
  CHECK_STRING (newname);
  filename = Fexpand_file_name (filename, Qnil);
  newname = Fexpand_file_name (newname, Qnil);

  /* If the input file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (filename, Qcopy_file);
  /* Likewise for output file name.  */
  if (NILP (handler))
    handler = Ffind_file_name_handler (newname, Qcopy_file);
  if (!NILP (handler))
  {
    UNGCPRO;
    return call5 (handler, Qcopy_file, filename, newname,
		  ok_if_already_exists, keep_time);
  }

  /* When second argument is a directory, copy the file into it.
     (copy-file "foo" "bar/") == (copy-file "foo" "bar/foo")
   */
  if (!NILP (Ffile_directory_p (newname)))
    {
      Lisp_Object args[3];
      struct gcpro ngcpro1;
      int i = 1;

      args[0] = newname;
      args[1] = Qnil; args[2] = Qnil;
      NGCPRO1 (*args);
      ngcpro1.nvars = 3;
      if (XSTRING_BYTE (newname, XSTRING_LENGTH (newname) - 1) != '/')
	args[i++] = build_string ("/");
      args[i++] = Ffile_name_nondirectory (filename);
      newname = Fconcat (i, args);
      NUNGCPRO;
    }

  if (NILP (ok_if_already_exists)
      || INTP (ok_if_already_exists))
    barf_or_query_if_file_exists (newname, "copy to it",
				  INTP (ok_if_already_exists), &out_st);
  else if (stat ((CONST char *) XSTRING_DATA (newname), &out_st) < 0)
    out_st.st_mode = 0;

  ifd = interruptible_open ((char *) XSTRING_DATA (filename), O_RDONLY | OPEN_BINARY, 0);
  if (ifd < 0)
    report_file_error ("Opening input file", list1 (filename));

  record_unwind_protect (close_file_unwind, make_int (ifd));

  /* We can only copy regular files and symbolic links.  Other files are not
     copyable by us. */
  input_file_statable_p = (fstat (ifd, &st) >= 0);

#ifndef WINDOWSNT
  if (out_st.st_mode != 0
      && st.st_dev == out_st.st_dev && st.st_ino == out_st.st_ino)
    {
      errno = 0;
      report_file_error ("Input and output files are the same",
			 list2 (filename, newname));
    }
#endif

#if defined (S_ISREG) && defined (S_ISLNK)
  if (input_file_statable_p)
    {
      if (!(S_ISREG (st.st_mode))
	  /* XEmacs: have to allow S_ISCHR in order to copy /dev/null */
#ifdef S_ISCHR
	  && !(S_ISCHR (st.st_mode))
#endif
	  && !(S_ISLNK (st.st_mode)))
	{
#if defined (EISDIR)
	  /* Get a better looking error message. */
	  errno = EISDIR;
#endif /* EISDIR */
	report_file_error ("Non-regular file", list1 (filename));
	}
    }
#endif /* S_ISREG && S_ISLNK */

  ofd = open( (char *) XSTRING_DATA (newname),
	      O_WRONLY | O_CREAT | O_TRUNC | OPEN_BINARY, CREAT_MODE);
  if (ofd < 0)
    report_file_error ("Opening output file", list1 (newname));

  {
    Lisp_Object ofd_locative = noseeum_cons (make_int (ofd), Qnil);

    record_unwind_protect (close_file_unwind, ofd_locative);

    while ((n = read_allowing_quit (ifd, buf, sizeof (buf))) > 0)
    {
      if (write_allowing_quit (ofd, buf, n) != n)
	report_file_error ("I/O error", list1 (newname));
    }

    /* Closing the output clobbers the file times on some systems.  */
    if (close (ofd) < 0)
      report_file_error ("I/O error", list1 (newname));

    if (input_file_statable_p)
    {
      if (!NILP (keep_time))
      {
        EMACS_TIME atime, mtime;
        EMACS_SET_SECS_USECS (atime, st.st_atime, 0);
        EMACS_SET_SECS_USECS (mtime, st.st_mtime, 0);
        if (set_file_times ((char *) XSTRING_DATA (newname), atime,
			    mtime))
	  report_file_error ("I/O error", list1 (newname));
      }
      chmod ((CONST char *) XSTRING_DATA (newname),
	     st.st_mode & 07777);
    }

    /* We'll close it by hand */
    XCAR (ofd_locative) = Qnil;

    /* Close ifd */
    unbind_to (speccount, Qnil);
  }

  UNGCPRO;
  return Qnil;
}

DEFUN ("make-directory-internal", Fmake_directory_internal, 1, 1, 0, /*
Create a directory.  One argument, a file name string.
*/
       (dirname_))
{
  /* This function can GC.  GC checked 1997.04.06. */
  char dir [MAXPATHLEN];
  Lisp_Object handler;
  struct gcpro gcpro1;

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

  GCPRO1 (dirname_);
  handler = Ffind_file_name_handler (dirname_, Qmake_directory_internal);
  UNGCPRO;
  if (!NILP (handler))
    return (call2 (handler, Qmake_directory_internal, dirname_));

  if (XSTRING_LENGTH (dirname_) > (Bytecount) (sizeof (dir) - 1))
    {
      return Fsignal (Qfile_error,
		      list3 (build_translated_string ("Creating directory"),
			     build_translated_string ("pathame too long"),
			     dirname_));
    }
  strncpy (dir, (char *) XSTRING_DATA (dirname_),
	   XSTRING_LENGTH (dirname_) + 1);

  if (dir [XSTRING_LENGTH (dirname_) - 1] == '/')
    dir [XSTRING_LENGTH (dirname_) - 1] = 0;

  if (mkdir (dir, 0777) != 0)
    report_file_error ("Creating directory", list1 (dirname_));

  return Qnil;
}

DEFUN ("delete-directory", Fdelete_directory, 1, 1, "FDelete directory: ", /*
Delete a directory.  One argument, a file name or directory name string.
*/
       (dirname_))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Lisp_Object handler;
  struct gcpro gcpro1;

  CHECK_STRING (dirname_);

  GCPRO1 (dirname_);
  dirname_ = Fexpand_file_name (dirname_, Qnil);
  dirname_ = Fdirectory_file_name (dirname_);

  handler = Ffind_file_name_handler (dirname_, Qdelete_directory);
  UNGCPRO;
  if (!NILP (handler))
    return (call2 (handler, Qdelete_directory, dirname_));

  if (rmdir ((char *) XSTRING_DATA (dirname_)) != 0)
    report_file_error ("Removing directory", list1 (dirname_));

  return Qnil;
}

DEFUN ("delete-file", Fdelete_file, 1, 1, "fDelete file: ", /*
Delete specified file.  One argument, a file name string.
If file has multiple names, it continues to exist with the other names.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Lisp_Object handler;
  struct gcpro gcpro1;

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

  GCPRO1 (filename);
  handler = Ffind_file_name_handler (filename, Qdelete_file);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qdelete_file, filename);

  if (0 > unlink ((char *) XSTRING_DATA (filename)))
    report_file_error ("Removing old name", list1 (filename));
  return Qnil;
}

static Lisp_Object
internal_delete_file_1 (Lisp_Object ignore, Lisp_Object ignore2)
{
  return Qt;
}

/* Delete file FILENAME, returning 1 if successful and 0 if failed.  */

int
internal_delete_file (Lisp_Object filename)
{
  /* This function can GC.  GC checked 1997.04.06. */
  return NILP (condition_case_1 (Qt, Fdelete_file, filename,
				 internal_delete_file_1, Qnil));
}

DEFUN ("rename-file", Frename_file, 2, 3,
       "fRename file: \nFRename %s to file: \np", /*
Rename FILE as NEWNAME.  Both args strings.
If file has names other than FILE, it continues to have those names.
Signals a `file-already-exists' error if a file NEWNAME already exists
unless optional third argument OK-IF-ALREADY-EXISTS is non-nil.
A number as third arg means request confirmation if NEWNAME already exists.
This is what happens in interactive use with M-x.
*/
       (filename, newname, ok_if_already_exists))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Lisp_Object handler;
  struct gcpro gcpro1, gcpro2;

  GCPRO2 (filename, newname);
  CHECK_STRING (filename);
  CHECK_STRING (newname);
  filename = Fexpand_file_name (filename, Qnil);
  newname = Fexpand_file_name (newname, Qnil);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (filename, Qrename_file);
  if (NILP (handler))
    handler = Ffind_file_name_handler (newname, Qrename_file);
  if (!NILP (handler))
  {
    UNGCPRO;
    return call4 (handler, Qrename_file,
		  filename, newname, ok_if_already_exists);
  }

  /* When second argument is a directory, rename the file into it.
     (rename-file "foo" "bar/") == (rename-file "foo" "bar/foo")
   */
  if (!NILP (Ffile_directory_p (newname)))
    {
      Lisp_Object args[3];
      struct gcpro ngcpro1;
      int i = 1;

      args[0] = newname;
      args[1] = Qnil; args[2] = Qnil;
      NGCPRO1 (*args);
      ngcpro1.nvars = 3;
      if (XSTRING_BYTE (newname, XSTRING_LENGTH (newname) - 1) != '/')
	args[i++] = build_string ("/");
      args[i++] = Ffile_name_nondirectory (filename);
      newname = Fconcat (i, args);
      NUNGCPRO;
    }

  if (NILP (ok_if_already_exists)
      || INTP (ok_if_already_exists))
    barf_or_query_if_file_exists (newname, "rename to it",
				  INTP (ok_if_already_exists), 0);

/* Syncing with FSF 19.34.6 note: FSF does not have conditional code for
   WINDOWSNT here; I've removed it.  --marcpa */

    /* FSFmacs only calls rename() here under BSD 4.1, and calls
       link() and unlink() otherwise, but that's bogus.  Sometimes
       rename() succeeds where link()/unlink() fail, and we have
       configure check for rename() and emulate using link()/unlink()
       if necessary. */
  if (0 > rename ((char *) XSTRING_DATA (filename),
		  (char *) XSTRING_DATA (newname)))
    {
      if (errno == EXDEV)
	{
	  Fcopy_file (filename, newname,
		      /* We have already prompted if it was an integer,
			 so don't have copy-file prompt again.  */
		      (NILP (ok_if_already_exists) ? Qnil : Qt),
                      Qt);
	  Fdelete_file (filename);
	}
      else
	{
	  report_file_error ("Renaming", list2 (filename, newname));
	}
    }
  UNGCPRO;
  return Qnil;
}

DEFUN ("add-name-to-file", Fadd_name_to_file, 2, 3,
       "fAdd name to file: \nFName to add to %s: \np", /*
Give FILE additional name NEWNAME.  Both args strings.
Signals a `file-already-exists' error if a file NEWNAME already exists
unless optional third argument OK-IF-ALREADY-EXISTS is non-nil.
A number as third arg means request confirmation if NEWNAME already exists.
This is what happens in interactive use with M-x.
*/
       (filename, newname, ok_if_already_exists))
{
  /* This function can GC.  GC checked 1997.04.06. */
  Lisp_Object handler;
  struct gcpro gcpro1, gcpro2;

  GCPRO2 (filename, newname);
  CHECK_STRING (filename);
  CHECK_STRING (newname);
  filename = Fexpand_file_name (filename, Qnil);
  newname = Fexpand_file_name (newname, Qnil);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (filename, Qadd_name_to_file);
  if (!NILP (handler))
    RETURN_UNGCPRO (call4 (handler, Qadd_name_to_file, filename,
			   newname, ok_if_already_exists));

  /* If the new name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (newname, Qadd_name_to_file);
  if (!NILP (handler))
    RETURN_UNGCPRO (call4 (handler, Qadd_name_to_file, filename,
			   newname, ok_if_already_exists));

  if (NILP (ok_if_already_exists)
      || INTP (ok_if_already_exists))
    barf_or_query_if_file_exists (newname, "make it a new name",
				  INTP (ok_if_already_exists), 0);
/* Syncing with FSF 19.34.6 note: FSF does not report a file error
   on NT here. --marcpa */
/* But FSF #defines link as sys_link which is supplied in nt.c. We can't do
   that because sysfile.h defines sys_link depending on ENCAPSULATE_LINK.
   Reverted to previous behavior pending a working fix. (jhar) */
#if defined(WINDOWSNT)
  /* Windows does not support this operation.  */
  report_file_error ("Adding new name", Flist (2, &filename));
#else /* not defined(WINDOWSNT) */

  unlink ((char *) XSTRING_DATA (newname));
  if (0 > link ((char *) XSTRING_DATA (filename),
		(char *) XSTRING_DATA (newname)))
    {
      report_file_error ("Adding new name",
			 list2 (filename, newname));
    }
#endif /* defined(WINDOWSNT) */

  UNGCPRO;
  return Qnil;
}

#ifdef S_IFLNK
DEFUN ("make-symbolic-link", Fmake_symbolic_link, 2, 3,
       "FMake symbolic link to file: \nFMake symbolic link to file %s: \np", /*
Make a symbolic link to FILENAME, named LINKNAME.  Both args strings.
Signals a `file-already-exists' error if a file LINKNAME already exists
unless optional third argument OK-IF-ALREADY-EXISTS is non-nil.
A number as third arg means request confirmation if LINKNAME already exists.
This happens for interactive use with M-x.
*/
       (filename, linkname, ok_if_already_exists))
{
  /* This function can GC.  GC checked 1997.06.04. */
  Lisp_Object handler;
  struct gcpro gcpro1, gcpro2;

  GCPRO2 (filename, linkname);
  CHECK_STRING (filename);
  CHECK_STRING (linkname);
  /* If the link target has a ~, we must expand it to get
     a truly valid file name.  Otherwise, do not expand;
     we want to permit links to relative file names.  */
  if (XSTRING_BYTE (filename, 0) == '~')
    filename = Fexpand_file_name (filename, Qnil);
  linkname = Fexpand_file_name (linkname, Qnil);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (filename, Qmake_symbolic_link);
  if (!NILP (handler))
    RETURN_UNGCPRO (call4 (handler, Qmake_symbolic_link, filename, linkname,
			   ok_if_already_exists));

  /* If the new link name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (linkname, Qmake_symbolic_link);
  if (!NILP (handler))
    RETURN_UNGCPRO (call4 (handler, Qmake_symbolic_link, filename,
			   linkname, ok_if_already_exists));

  if (NILP (ok_if_already_exists)
      || INTP (ok_if_already_exists))
    barf_or_query_if_file_exists (linkname, "make it a link",
				  INTP (ok_if_already_exists), 0);

  unlink ((char *) XSTRING_DATA (linkname));
  if (0 > symlink ((char *) XSTRING_DATA (filename),
		   (char *) XSTRING_DATA (linkname)))
    {
      report_file_error ("Making symbolic link",
			 list2 (filename, linkname));
    }
  UNGCPRO;
  return Qnil;
}
#endif /* S_IFLNK */

#ifdef HPUX_NET

DEFUN ("sysnetunam", Fsysnetunam, 2, 2, 0, /*
Open a network connection to PATH using LOGIN as the login string.
*/
       (path, login))
{
  int netresult;

  CHECK_STRING (path);
  CHECK_STRING (login);

  /* netunam, being a strange-o system call only used once, is not
     encapsulated. */
  {
    char *path_ext;
    char *login_ext;

    GET_C_STRING_FILENAME_DATA_ALLOCA (path, path_ext);
    GET_C_STRING_EXT_DATA_ALLOCA (login, FORMAT_OS, login_ext);

    netresult = netunam (path_ext, login_ext);
  }

  if (netresult == -1)
    return Qnil;
  else
    return Qt;
}
#endif /* HPUX_NET */

DEFUN ("file-name-absolute-p", Ffile_name_absolute_p, 1, 1, 0, /*
Return t if file FILENAME specifies an absolute path name.
On Unix, this is a name starting with a `/' or a `~'.
*/
       (filename))
{
  /* This function does not GC */
  Bufbyte *ptr;

  CHECK_STRING (filename);
  ptr = XSTRING_DATA (filename);
  return (IS_DIRECTORY_SEP (*ptr) || *ptr == '~'
#ifdef WINDOWSNT
	  || (IS_DRIVE (*ptr) && ptr[1] == ':' && IS_DIRECTORY_SEP (ptr[2]))
#endif
	  ) ? Qt : Qnil;
}

/* Return nonzero if file FILENAME exists and can be executed.  */

static int
check_executable (char *filename)
{
#ifdef WINDOWSNT
  struct stat st;
  if (stat (filename, &st) < 0)
    return 0;
  return ((st.st_mode & S_IEXEC) != 0);
#else /* not WINDOWSNT */
#ifdef HAVE_EACCESS
  return eaccess (filename, 1) >= 0;
#else
  /* Access isn't quite right because it uses the real uid
     and we really want to test with the effective uid.
     But Unix doesn't give us a right way to do it.  */
  return access (filename, 1) >= 0;
#endif /* HAVE_EACCESS */
#endif /* not WINDOWSNT */
}

/* Return nonzero if file FILENAME exists and can be written.  */

static int
check_writable (CONST char *filename)
{
#ifdef HAVE_EACCESS
  return (eaccess (filename, 2) >= 0);
#else
  /* Access isn't quite right because it uses the real uid
     and we really want to test with the effective uid.
     But Unix doesn't give us a right way to do it.
     Opening with O_WRONLY could work for an ordinary file,
     but would lose for directories.  */
  return (access (filename, 2) >= 0);
#endif
}

DEFUN ("file-exists-p", Ffile_exists_p, 1, 1, 0, /*
Return t if file FILENAME exists.  (This does not mean you can read it.)
See also `file-readable-p' and `file-attributes'.
*/
       (filename))
{
  /* This function can call lisp */
  Lisp_Object abspath;
  Lisp_Object handler;
  struct stat statbuf;
  struct gcpro gcpro1;

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

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qfile_exists_p);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_exists_p, abspath);

  return stat ((char *) XSTRING_DATA (abspath), &statbuf) >= 0 ? Qt : Qnil;
}

DEFUN ("file-executable-p", Ffile_executable_p, 1, 1, 0, /*
Return t if FILENAME can be executed by you.
For a directory, this means you can access files in that directory.
*/
       (filename))

{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath;
  Lisp_Object handler;
  struct gcpro gcpro1;

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

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qfile_executable_p);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_executable_p, abspath);

  return check_executable ((char *) XSTRING_DATA (abspath)) ? Qt : Qnil;
}

DEFUN ("file-readable-p", Ffile_readable_p, 1, 1, 0, /*
Return t if file FILENAME exists and you can read it.
See also `file-exists-p' and `file-attributes'.
*/
       (filename))
{
  /* This function can GC */
  Lisp_Object abspath = Qnil;
  Lisp_Object handler;
  struct gcpro gcpro1;
  GCPRO1 (abspath);

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

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

#if defined(WINDOWSNT) || defined(__CYGWIN32__)
  /* Under MS-DOS and Windows, open does not work for directories.  */
  UNGCPRO;
  if (access (XSTRING_DATA (abspath), 0) == 0)
    return Qt;
  else
    return Qnil;
#else /* not WINDOWSNT */
  {
    int desc = interruptible_open ((char *) XSTRING_DATA (abspath), O_RDONLY | OPEN_BINARY, 0);
    UNGCPRO;
    if (desc < 0)
      return Qnil;
    close (desc);
    return Qt;
  }
#endif /* not WINDOWSNT */
}

/* Having this before file-symlink-p mysteriously caused it to be forgotten
   on the RT/PC.  */
DEFUN ("file-writable-p", Ffile_writable_p, 1, 1, 0, /*
Return t if file FILENAME can be written or created by you.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath, dir;
  Lisp_Object handler;
  struct stat statbuf;
  struct gcpro gcpro1;

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

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qfile_writable_p);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_writable_p, abspath);

  if (stat ((char *) XSTRING_DATA (abspath), &statbuf) >= 0)
    return (check_writable ((char *) XSTRING_DATA (abspath))
	    ? Qt : Qnil);


  GCPRO1 (abspath);
  dir = Ffile_name_directory (abspath);
  UNGCPRO;
  return (check_writable (!NILP (dir) ? (char *) XSTRING_DATA (dir)
			  : "")
	  ? Qt : Qnil);
}

DEFUN ("file-symlink-p", Ffile_symlink_p, 1, 1, 0, /*
Return non-nil if file FILENAME is the name of a symbolic link.
The value is the name of the file to which it is linked.
Otherwise returns nil.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.10. */
#ifdef S_IFLNK
  char *buf;
  int bufsize;
  int valsize;
  Lisp_Object val;
  Lisp_Object handler;
  struct gcpro gcpro1;

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

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (filename);
  handler = Ffind_file_name_handler (filename, Qfile_symlink_p);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_symlink_p, filename);

  bufsize = 100;
  while (1)
    {
      buf = xnew_array_and_zero (char, bufsize);
      valsize = readlink ((char *) XSTRING_DATA (filename),
			  buf, bufsize);
      if (valsize < bufsize) break;
      /* Buffer was not long enough */
      xfree (buf);
      bufsize *= 2;
    }
  if (valsize == -1)
    {
      xfree (buf);
      return Qnil;
    }
  val = make_string ((Bufbyte *) buf, valsize);
  xfree (buf);
  return val;
#else /* not S_IFLNK */
  return Qnil;
#endif /* not S_IFLNK */
}

DEFUN ("file-directory-p", Ffile_directory_p, 1, 1, 0, /*
Return t if file FILENAME is the name of a directory as a file.
A directory name spec may be given instead; then the value is t
if the directory so specified exists and really is a directory.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath;
  struct stat st;
  Lisp_Object handler;
  struct gcpro gcpro1;

  GCPRO1 (current_buffer->directory);
  abspath = expand_and_dir_to_file (filename,
				    current_buffer->directory);
  UNGCPRO;

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qfile_directory_p);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_directory_p, abspath);

  if (stat ((char *) XSTRING_DATA (abspath), &st) < 0)
    return Qnil;
  return (st.st_mode & S_IFMT) == S_IFDIR ? Qt : Qnil;
}

DEFUN ("file-accessible-directory-p", Ffile_accessible_directory_p, 1, 1, 0, /*
Return t if file FILENAME is the name of a directory as a file,
and files in that directory can be opened by you.  In order to use a
directory as a buffer's current directory, this predicate must return true.
A directory name spec may be given instead; then the value is t
if the directory so specified exists and really is a readable and
searchable directory.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object handler;

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

#if !defined(WINDOWSNT)
  if (NILP (Ffile_directory_p (filename)))
      return (Qnil);
  else
    return Ffile_executable_p (filename);
#else
  {
    int tem;
    struct gcpro gcpro1;
    /* It's an unlikely combination, but yes we really do need to gcpro:
       Suppose that file-accessible-directory-p has no handler, but
       file-directory-p does have a handler; this handler causes a GC which
       relocates the string in `filename'; and finally file-directory-p
       returns non-nil.  Then we would end up passing a garbaged string
       to file-executable-p.  */
    GCPRO1 (filename);
    tem = (NILP (Ffile_directory_p (filename))
	   || NILP (Ffile_executable_p (filename)));
    UNGCPRO;
    return tem ? Qnil : Qt;
  }
#endif /* !defined(WINDOWSNT) */
}

DEFUN ("file-regular-p", Ffile_regular_p, 1, 1, 0, /*
Return t if file FILENAME is the name of a regular file.
This is the sort of file that holds an ordinary stream of data bytes.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath;
  struct stat st;
  Lisp_Object handler;
  struct gcpro gcpro1;

  GCPRO1 (current_buffer->directory);
  abspath = expand_and_dir_to_file (filename, current_buffer->directory);
  UNGCPRO;

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qfile_regular_p);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_regular_p, abspath);

  if (stat ((char *) XSTRING_DATA (abspath), &st) < 0)
    return Qnil;
  return (st.st_mode & S_IFMT) == S_IFREG ? Qt : Qnil;
}

DEFUN ("file-modes", Ffile_modes, 1, 1, 0, /*
Return mode bits of FILE, as an integer.
*/
       (filename))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath;
  struct stat st;
  Lisp_Object handler;
  struct gcpro gcpro1;

  GCPRO1 (current_buffer->directory);
  abspath = expand_and_dir_to_file (filename,
				    current_buffer->directory);
  UNGCPRO;

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qfile_modes);
  UNGCPRO;
  if (!NILP (handler))
    return call2 (handler, Qfile_modes, abspath);

  if (stat ((char *) XSTRING_DATA (abspath), &st) < 0)
    return Qnil;
  /* Syncing with FSF 19.34.6 note: not in FSF, #if 0'ed out here. */
#if 0
#ifdef DOS_NT
  if (check_executable (XSTRING_DATA (abspath)))
    st.st_mode |= S_IEXEC;
#endif /* DOS_NT */
#endif /* 0 */

  return make_int (st.st_mode & 07777);
}

DEFUN ("set-file-modes", Fset_file_modes, 2, 2, 0, /*
Set mode bits of FILE to MODE (an integer).
Only the 12 low bits of MODE are used.
*/
       (filename, mode))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath;
  Lisp_Object handler;
  struct gcpro gcpro1;

  GCPRO1 (current_buffer->directory);
  abspath = Fexpand_file_name (filename, current_buffer->directory);
  UNGCPRO;

  CHECK_INT (mode);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  GCPRO1 (abspath);
  handler = Ffind_file_name_handler (abspath, Qset_file_modes);
  UNGCPRO;
  if (!NILP (handler))
    return call3 (handler, Qset_file_modes, abspath, mode);

  if (chmod ((char *) XSTRING_DATA (abspath), XINT (mode)) < 0)
    report_file_error ("Doing chmod", list1 (abspath));

  return Qnil;
}

DEFUN ("set-default-file-modes", Fset_default_file_modes, 1, 1, 0, /*
Set the file permission bits for newly created files.
MASK should be an integer; if a permission's bit in MASK is 1,
subsequently created files will not have that permission enabled.
Only the low 9 bits are used.
This setting is inherited by subprocesses.
*/
       (mode))
{
  CHECK_INT (mode);

  umask ((~ XINT (mode)) & 0777);

  return Qnil;
}

DEFUN ("default-file-modes", Fdefault_file_modes, 0, 0, 0, /*
Return the default file protection for created files.
The umask value determines which permissions are enabled in newly
created files.  If a permission's bit in the umask is 1, subsequently
created files will not have that permission enabled.
*/
       ())
{
  int mode;

  mode = umask (0);
  umask (mode);

  return make_int ((~ mode) & 0777);
}

DEFUN ("unix-sync", Funix_sync, 0, 0, "", /*
Tell Unix to finish all pending disk updates.
*/
       ())
{
#ifndef WINDOWSNT
  sync ();
#endif
  return Qnil;
}


DEFUN ("file-newer-than-file-p", Ffile_newer_than_file_p, 2, 2, 0, /*
Return t if file FILE1 is newer than file FILE2.
If FILE1 does not exist, the answer is nil;
otherwise, if FILE2 does not exist, the answer is t.
*/
       (file1, file2))
{
  /* This function can GC.  GC checked 1997.04.10. */
  Lisp_Object abspath1, abspath2;
  struct stat st;
  int mtime1;
  Lisp_Object handler;
  struct gcpro gcpro1, gcpro2, gcpro3;

  CHECK_STRING (file1);
  CHECK_STRING (file2);

  abspath1 = Qnil;
  abspath2 = Qnil;

  GCPRO3 (abspath1, abspath2, current_buffer->directory);
  abspath1 = expand_and_dir_to_file (file1, current_buffer->directory);
  abspath2 = expand_and_dir_to_file (file2, current_buffer->directory);

  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
  handler = Ffind_file_name_handler (abspath1, Qfile_newer_than_file_p);
  if (NILP (handler))
    handler = Ffind_file_name_handler (abspath2, Qfile_newer_than_file_p);
  UNGCPRO;
  if (!NILP (handler))
    return call3 (handler, Qfile_newer_than_file_p, abspath1,
		  abspath2);

  if (stat ((char *) XSTRING_DATA (abspath1), &st) < 0)
    return Qnil;

  mtime1 = st.st_mtime;

  if (stat ((char *) XSTRING_DATA (abspath2), &st) < 0)
    return Qt;

  return (mtime1 > st.st_mtime) ? Qt : Qnil;
}


/* Stack sizes > 2**16 is a good way to elicit compiler bugs */
/* #define READ_BUF_SIZE (2 << 16) */
#define READ_BUF_SIZE (1 << 15)

DEFUN ("insert-file-contents-internal", Finsert_file_contents_internal,
       1, 7, 0, /*
Insert contents of file FILENAME after point; no coding-system frobbing.
This function is identical to `insert-file-contents' except for the
handling of the CODESYS and USED-CODESYS arguments under
XEmacs/Mule. (When Mule support is not present, both functions are
identical and ignore the CODESYS and USED-CODESYS arguments.)

If support for Mule exists in this Emacs, the file is decoded according
to CODESYS; if omitted, no conversion happens.  If USED-CODESYS is non-nil,
it should be a symbol, and the actual coding system that was used for the
decoding is stored into it.  It will in general be different from CODESYS
if CODESYS specifies automatic encoding detection or end-of-line detection.

Currently BEG and END refer to byte positions (as opposed to character
positions), even in Mule. (Fixing this is very difficult.)
*/
       (filename, visit, beg, end, replace, codesys, used_codesys))
{
  /* This function can call lisp */
  /* #### dmoore - this function hasn't been checked for gc recently */
  struct stat st;
  int fd;
  int saverrno = 0;
  Charcount inserted = 0;
  int speccount;
  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;
  Lisp_Object handler = Qnil, val;
  int total;
  Bufbyte read_buf[READ_BUF_SIZE];
  int mc_count;
  struct buffer *buf = current_buffer;
  Lisp_Object curbuf;
  int not_regular = 0;

  if (buf->base_buffer && ! NILP (visit))
    error ("Cannot do file visiting in an indirect buffer");

  /* No need to call Fbarf_if_buffer_read_only() here.
     That's called in begin_multiple_change() or wherever. */

  val = Qnil;

  /* #### dmoore - should probably check in various places to see if
     curbuf was killed and if so signal an error? */

  XSETBUFFER (curbuf, buf);

  GCPRO5 (filename, val, visit, handler, curbuf);

  mc_count = (NILP (replace)) ?
    begin_multiple_change (buf, BUF_PT  (buf), BUF_PT (buf)) :
    begin_multiple_change (buf, BUF_BEG (buf), BUF_Z  (buf));

  speccount = specpdl_depth (); /* begin_multiple_change also adds
				   an unwind_protect */

  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, Qinsert_file_contents);
  if (!NILP (handler))
    {
      val = call6 (handler, Qinsert_file_contents, filename,
		   visit, beg, end, replace);
      goto handled;
    }

#ifdef FILE_CODING
  if (!NILP (used_codesys))
    CHECK_SYMBOL (used_codesys);
#endif

  if ( (!NILP (beg) || !NILP (end)) && !NILP (visit) )
    error ("Attempt to visit less than an entire file");

  fd = -1;

  if (
#ifndef APOLLO
      (stat ((char *) XSTRING_DATA (filename), &st) < 0)
#else /* APOLLO */
      /* Don't even bother with interruptible_open.  APOLLO sucks. */
      ((fd = open ((char *) XSTRING_DATA (filename), O_RDONLY | OPEN_BINARY, 0)) < 0
       || fstat (fd, &st) < 0)
#endif /* APOLLO */
      )
    {
      if (fd >= 0) close (fd);
    badopen:
      if (NILP (visit))
	report_file_error ("Opening input file", list1 (filename));
      st.st_mtime = -1;
      goto notfound;
    }

#ifdef S_IFREG
  /* Signal an error if we are accessing a non-regular file, with
     REPLACE, BEG or END being non-nil.  */
  if (!S_ISREG (st.st_mode))
    {
      not_regular = 1;

      if (!NILP (visit))
	goto notfound;

      if (!NILP (replace) || !NILP (beg) || !NILP (end))
	{
	  end_multiple_change (buf, mc_count);

	  return Fsignal (Qfile_error,
			  list2 (build_translated_string("not a regular file"),
				 filename));
	}
    }
#endif /* S_IFREG */

  if (!NILP (beg))
    CHECK_INT (beg);
  else
    beg = Qzero;

  if (!NILP (end))
    CHECK_INT (end);

  if (fd < 0)
    {
      if ((fd = interruptible_open ((char *) XSTRING_DATA (filename),
				    O_RDONLY | OPEN_BINARY, 0)) < 0)
	goto badopen;
    }

  /* Replacement should preserve point as it preserves markers.  */
  if (!NILP (replace))
    record_unwind_protect (restore_point_unwind, Fpoint_marker (Qnil, Qnil));

  record_unwind_protect (close_file_unwind, make_int (fd));

  /* Supposedly happens on VMS.  */
  if (st.st_size < 0)
    error ("File size is negative");

  if (NILP (end))
    {
      if (!not_regular)
	{
	  end = make_int (st.st_size);
	  if (XINT (end) != st.st_size)
	    error ("Maximum buffer size exceeded");
	}
    }

  /* If requested, replace the accessible part of the buffer
     with the file contents.  Avoid replacing text at the
     beginning or end of the buffer that matches the file contents;
     that preserves markers pointing to the unchanged parts.  */
#if !defined (FILE_CODING)
  /* The replace-mode code currently only works when the assumption
     'one byte == one char' holds true.  This fails Mule because
     files may contain multibyte characters.  It holds under Windows NT
     provided we convert CRLF into LF. */
# define FSFMACS_SPEEDY_INSERT
#endif /* !defined (FILE_CODING) */

#ifndef FSFMACS_SPEEDY_INSERT
  if (!NILP (replace))
    {
      buffer_delete_range (buf, BUF_BEG (buf), BUF_Z (buf),
			   !NILP (visit) ? INSDEL_NO_LOCKING : 0);
    }
#else /* FSFMACS_SPEEDY_INSERT */
  if (!NILP (replace))
    {
      char buffer[1 << 14];
      Bufpos same_at_start = BUF_BEGV (buf);
      Bufpos same_at_end = BUF_ZV (buf);
      int overlap;

      /* Count how many chars at the start of the file
	 match the text at the beginning of the buffer.  */
      while (1)
	{
	  int nread;
	  Bufpos bufpos;
	  nread = read_allowing_quit (fd, buffer, sizeof buffer);
	  if (nread < 0)
	    error ("IO error reading %s: %s",
		   XSTRING_DATA (filename), strerror (errno));
	  else if (nread == 0)
	    break;
	  bufpos = 0;
	  while (bufpos < nread && same_at_start < BUF_ZV (buf)
		 && BUF_FETCH_CHAR (buf, same_at_start) == buffer[bufpos])
	    same_at_start++, bufpos++;
	  /* If we found a discrepancy, stop the scan.
	     Otherwise loop around and scan the next bufferful.  */
	  if (bufpos != nread)
	    break;
	}
      /* If the file matches the buffer completely,
	 there's no need to replace anything.  */
      if (same_at_start - BUF_BEGV (buf) == st.st_size)
	{
	  close (fd);
          unbind_to (speccount, Qnil);
	  /* Truncate the buffer to the size of the file.  */
	  buffer_delete_range (buf, same_at_start, same_at_end,
			       !NILP (visit) ? INSDEL_NO_LOCKING : 0);
	  goto handled;
	}
      /* Count how many chars at the end of the file
	 match the text at the end of the buffer.  */
      while (1)
	{
	  int total_read, nread;
	  Bufpos bufpos, curpos, trial;

	  /* At what file position are we now scanning?  */
	  curpos = st.st_size - (BUF_ZV (buf) - same_at_end);
	  /* If the entire file matches the buffer tail, stop the scan.  */
	  if (curpos == 0)
	    break;
	  /* How much can we scan in the next step?  */
	  trial = min (curpos, (Bufpos) sizeof (buffer));
	  if (lseek (fd, curpos - trial, 0) < 0)
	    report_file_error ("Setting file position", list1 (filename));

	  total_read = 0;
	  while (total_read < trial)
	    {
	      nread = read_allowing_quit (fd, buffer + total_read,
					  trial - total_read);
	      if (nread <= 0)
		report_file_error ("IO error reading file", list1 (filename));
	      total_read += nread;
	    }
	  /* Scan this bufferful from the end, comparing with
	     the Emacs buffer.  */
	  bufpos = total_read;
	  /* Compare with same_at_start to avoid counting some buffer text
	     as matching both at the file's beginning and at the end.  */
	  while (bufpos > 0 && same_at_end > same_at_start
		 && BUF_FETCH_CHAR (buf, same_at_end - 1) ==
		 buffer[bufpos - 1])
	    same_at_end--, bufpos--;
	  /* If we found a discrepancy, stop the scan.
	     Otherwise loop around and scan the preceding bufferful.  */
	  if (bufpos != 0)
	    break;
	  /* If display current starts at beginning of line,
	     keep it that way.  */
	  if (XBUFFER (XWINDOW (Fselected_window (Qnil))->buffer) == buf)
	    XWINDOW (Fselected_window (Qnil))->start_at_line_beg =
	      !NILP (Fbolp (make_buffer (buf)));
	}

      /* Don't try to reuse the same piece of text twice.  */
      overlap = same_at_start - BUF_BEGV (buf) -
	(same_at_end + st.st_size - BUF_ZV (buf));
      if (overlap > 0)
	same_at_end += overlap;

      /* Arrange to read only the nonmatching middle part of the file.  */
      beg = make_int (same_at_start - BUF_BEGV (buf));
      end = make_int (st.st_size - (BUF_ZV (buf) - same_at_end));

      buffer_delete_range (buf, same_at_start, same_at_end,
			   !NILP (visit) ? INSDEL_NO_LOCKING : 0);
      /* Insert from the file at the proper position.  */
      BUF_SET_PT (buf, same_at_start);
    }
#endif /* FSFMACS_SPEEDY_INSERT */

  if (!not_regular)
    {
      total = XINT (end) - XINT (beg);

      /* Make sure point-max won't overflow after this insertion.  */
      if (total != XINT (make_int (total)))
	error ("Maximum buffer size exceeded");
    }
  else
    /* For a special file, all we can do is guess.  The value of -1
       will make the stream functions read as much as possible.  */
    total = -1;

  if (XINT (beg) != 0
#ifdef FSFMACS_SPEEDY_INSERT
      /* why was this here? asked jwz.  The reason is that the replace-mode
	 connivings above will normally put the file pointer other than
	 where it should be. */
      || !NILP (replace)
#endif /* !FSFMACS_SPEEDY_INSERT */
      )
    {
      if (lseek (fd, XINT (beg), 0) < 0)
	report_file_error ("Setting file position", list1 (filename));
    }

  {
    Bufpos cur_point = BUF_PT (buf);
    struct gcpro ngcpro1;
    Lisp_Object stream = make_filedesc_input_stream (fd, 0, total,
						     LSTR_ALLOW_QUIT);

    NGCPRO1 (stream);
    Lstream_set_buffering (XLSTREAM (stream), LSTREAM_BLOCKN_BUFFERED, 65536);
#ifdef FILE_CODING
    stream = make_decoding_input_stream
      (XLSTREAM (stream), Fget_coding_system (codesys));
    Lstream_set_character_mode (XLSTREAM (stream));
    Lstream_set_buffering (XLSTREAM (stream), LSTREAM_BLOCKN_BUFFERED, 65536);
#endif /* FILE_CODING */

    record_unwind_protect (delete_stream_unwind, stream);

    /* No need to limit the amount of stuff we attempt to read. (It would
       be incorrect, anyway, when Mule is enabled.) Instead, the limiting
       occurs inside of the filedesc stream. */
    while (1)
      {
	Bytecount this_len;
	Charcount cc_inserted;

	QUIT;
	this_len = Lstream_read (XLSTREAM (stream), read_buf,
				 sizeof (read_buf));

	if (this_len <= 0)
	  {
	    if (this_len < 0)
	      saverrno = errno;
	    break;
	  }

	cc_inserted = buffer_insert_raw_string_1 (buf, cur_point, read_buf,
						  this_len,
						  !NILP (visit)
						  ? INSDEL_NO_LOCKING : 0);
	inserted  += cc_inserted;
	cur_point += cc_inserted;
      }
#ifdef FILE_CODING
    if (!NILP (used_codesys))
      {
	Fset (used_codesys,
	      XCODING_SYSTEM_NAME (decoding_stream_coding_system (XLSTREAM (stream))));
      }
#endif /* FILE_CODING */
    NUNGCPRO;
  }

  /* Close the file/stream */
  unbind_to (speccount, Qnil);

  if (saverrno != 0)
    {
      error ("IO error reading %s: %s",
	     XSTRING_DATA (filename), strerror (saverrno));
    }

 notfound:
 handled:

  end_multiple_change (buf, mc_count);

  if (!NILP (visit))
    {
      if (!EQ (buf->undo_list, Qt))
	buf->undo_list = Qnil;
#ifdef APOLLO
      stat ((char *) XSTRING_DATA (filename), &st);
#endif
      if (NILP (handler))
	{
	  buf->modtime = st.st_mtime;
	  buf->filename = filename;
	  /* XEmacs addition: */
	  /* This function used to be in C, ostensibly so that
	     it could be called here.  But that's just silly.
	     There's no reason C code can't call out to Lisp
	     code, and it's a lot cleaner this way. */
	  if (!NILP (Ffboundp (Qcompute_buffer_file_truename)))
	    call1 (Qcompute_buffer_file_truename, make_buffer (buf));
	}
      BUF_SAVE_MODIFF (buf) = BUF_MODIFF (buf);
      buf->auto_save_modified = BUF_MODIFF (buf);
      buf->saved_size = make_int (BUF_SIZE (buf));
#ifdef CLASH_DETECTION
      if (NILP (handler))
	{
	  if (!NILP (buf->file_truename))
	    unlock_file (buf->file_truename);
	  unlock_file (filename);
	}
#endif /* CLASH_DETECTION */
      if (not_regular)
	RETURN_UNGCPRO (Fsignal (Qfile_error,
				 list2 (build_string ("not a regular file"),
			         filename)));

      /* If visiting nonexistent file, return nil.  */
      if (buf->modtime == -1)
	report_file_error ("Opening input file",
			   list1 (filename));
    }

  /* Decode file format */
  if (inserted > 0)
    {
      Lisp_Object insval = call3 (Qformat_decode,
                                  Qnil, make_int (inserted), visit);
      CHECK_INT (insval);
      inserted = XINT (insval);
    }

  if (inserted > 0)
    {
      Lisp_Object p;
      struct gcpro ngcpro1;

      NGCPRO1 (p);
      EXTERNAL_LIST_LOOP (p, Vafter_insert_file_functions)
	{
	  Lisp_Object insval =
	    call1 (XCAR (p), make_int (inserted));
	  if (!NILP (insval))
	    {
	      CHECK_NATNUM (insval);
	      inserted = XINT (insval);
	    }
	  QUIT;
	}
      NUNGCPRO;
    }

  UNGCPRO;

  if (!NILP (val))
    return (val);
  else
    return (list2 (filename, make_int (inserted)));
}


static int a_write (Lisp_Object outstream, Lisp_Object instream, int pos,
		    Lisp_Object *annot);
static Lisp_Object build_annotations (Lisp_Object start, Lisp_Object end);

/* If build_annotations switched buffers, switch back to BUF.
   Kill the temporary buffer that was selected in the meantime.  */

static Lisp_Object
build_annotations_unwind (Lisp_Object buf)
{
  Lisp_Object tembuf;

  if (XBUFFER (buf) == current_buffer)
    return Qnil;
  tembuf = Fcurrent_buffer ();
  Fset_buffer (buf);
  Fkill_buffer (tembuf);
  return Qnil;
}

DEFUN ("write-region-internal", Fwrite_region_internal, 3, 7,
       "r\nFWrite region to file: ", /*
Write current region into specified file; no coding-system frobbing.
This function is identical to `write-region' except for the handling
of the CODESYS argument under XEmacs/Mule. (When Mule support is not
present, both functions are identical and ignore the CODESYS argument.)
If support for Mule exists in this Emacs, the file is encoded according
to the value of CODESYS.  If this is nil, no code conversion occurs.
*/
       (start, end, filename, append, visit, lockname, codesys))
{
  /* This function can call lisp */
  int desc;
  int failure;
  int save_errno = 0;
  struct stat st;
  Lisp_Object fn;
  int speccount = specpdl_depth ();
  int visiting_other = STRINGP (visit);
  int visiting = (EQ (visit, Qt) || visiting_other);
  int quietly = (!visiting && !NILP (visit));
  Lisp_Object visit_file = Qnil;
  Lisp_Object annotations = Qnil;
  struct buffer *given_buffer;
  Bufpos start1, end1;

  /* #### dmoore - if Fexpand_file_name or handlers kill the buffer,
     we should signal an error rather than blissfully continuing
     along.  ARGH, this function is going to lose lose lose.  We need
     to protect the current_buffer from being destroyed, but the
     multiple return points make this a pain in the butt. */

#ifdef FILE_CODING
  codesys = Fget_coding_system (codesys);
#endif /* FILE_CODING */

  if (current_buffer->base_buffer && ! NILP (visit))
    error ("Cannot do file visiting in an indirect buffer");

  if (!NILP (start) && !STRINGP (start))
    get_buffer_range_char (current_buffer, start, end, &start1, &end1, 0);

  {
    Lisp_Object handler;
    struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;

    GCPRO5 (start, filename, visit, visit_file, lockname);

    if (visiting_other)
      visit_file = Fexpand_file_name (visit, Qnil);
    else
      visit_file = filename;
    filename = Fexpand_file_name (filename, Qnil);

    UNGCPRO;

    if (NILP (lockname))
      lockname = visit_file;

    /* If the file name has special constructs in it,
       call the corresponding file handler.  */
    handler = Ffind_file_name_handler (filename, Qwrite_region);
    /* If FILENAME has no handler, see if VISIT has one.  */
    if (NILP (handler) && STRINGP (visit))
      handler = Ffind_file_name_handler (visit, Qwrite_region);

    if (!NILP (handler))
      {
        Lisp_Object val = call8 (handler, Qwrite_region, start, end,
                                 filename, append, visit, lockname, codesys);
	if (visiting)
	  {
	    BUF_SAVE_MODIFF (current_buffer) = BUF_MODIFF (current_buffer);
	    current_buffer->saved_size = make_int (BUF_SIZE (current_buffer));
	    current_buffer->filename = visit_file;
	    MARK_MODELINE_CHANGED;
	  }
	return val;
      }
  }

#ifdef CLASH_DETECTION
  if (!auto_saving)
    {
      Lisp_Object curbuf;
      struct gcpro gcpro1, gcpro2, gcpro3, gcpro4, gcpro5;

      XSETBUFFER (curbuf, current_buffer);
      GCPRO5 (start, filename, visit_file, lockname, curbuf);
      lock_file (lockname);
      UNGCPRO;
    }
#endif /* CLASH_DETECTION */

  /* Special kludge to simplify auto-saving.  */
  if (NILP (start))
    {
      start1 = BUF_BEG (current_buffer);
      end1 = BUF_Z (current_buffer);
    }

  record_unwind_protect (build_annotations_unwind, Fcurrent_buffer ());

  given_buffer = current_buffer;
  annotations = build_annotations (start, end);
  if (current_buffer != given_buffer)
    {
      start1 = BUF_BEGV (current_buffer);
      end1 = BUF_ZV (current_buffer);
    }

  fn = filename;
  desc = -1;
  if (!NILP (append))
    {
      desc = open ((char *) XSTRING_DATA (fn), O_WRONLY | OPEN_BINARY, 0);
    }
  if (desc < 0)
    {
      desc = open ((char *) XSTRING_DATA (fn),
                   (O_WRONLY | O_TRUNC | O_CREAT | OPEN_BINARY),
		   ((auto_saving) ? auto_save_mode_bits : CREAT_MODE));
    }

  if (desc < 0)
    {
#ifdef CLASH_DETECTION
      save_errno = errno;
      if (!auto_saving) unlock_file (lockname);
      errno = save_errno;
#endif /* CLASH_DETECTION */
      report_file_error ("Opening output file", list1 (filename));
    }

  {
    Lisp_Object desc_locative = Fcons (make_int (desc), Qnil);
    Lisp_Object instream = Qnil, outstream = Qnil;
    struct gcpro gcpro1, gcpro2;
    /* need to gcpro; QUIT could happen out of call to write() */
    GCPRO2 (instream, outstream);

    record_unwind_protect (close_file_unwind, desc_locative);

    if (!NILP (append))
      {
	if (lseek (desc, 0, 2) < 0)
	  {
#ifdef CLASH_DETECTION
	    if (!auto_saving) unlock_file (lockname);
#endif /* CLASH_DETECTION */
	    report_file_error ("Lseek error",
			       list1 (filename));
	  }
      }

    failure = 0;

    /* Note: I tried increasing the buffering size, along with
       various other tricks, but nothing seemed to make much of
       a difference in the time it took to save a large file.
       (Actually that's not true.  With a local disk, changing
       the buffer size doesn't seem to make much difference.
       With an NFS-mounted disk, it could make a lot of difference
       because you're affecting the number of network requests
       that need to be made, and there could be a large latency
       for each request.  So I've increased the buffer size
       to 64K.) */
    outstream = make_filedesc_output_stream (desc, 0, -1, 0);
    Lstream_set_buffering (XLSTREAM (outstream),
			   LSTREAM_BLOCKN_BUFFERED, 65536);
#ifdef FILE_CODING
    outstream =
      make_encoding_output_stream (XLSTREAM (outstream), codesys);
    Lstream_set_buffering (XLSTREAM (outstream),
			   LSTREAM_BLOCKN_BUFFERED, 65536);
#endif /* FILE_CODING */
    if (STRINGP (start))
      {
	instream = make_lisp_string_input_stream (start, 0, -1);
	start1 = 0;
      }
    else
      instream = make_lisp_buffer_input_stream (current_buffer, start1, end1,
						LSTR_SELECTIVE |
						LSTR_IGNORE_ACCESSIBLE);
    failure = (0 > (a_write (outstream, instream, start1,
			     &annotations)));
    save_errno = errno;
    /* Note that this doesn't close the desc since we created the
       stream without the LSTR_CLOSING flag, but it does
       flush out any buffered data. */
    if (Lstream_close (XLSTREAM (outstream)) < 0)
      {
	failure = 1;
	save_errno = errno;
      }
    Lstream_close (XLSTREAM (instream));
    UNGCPRO;

#ifdef HAVE_FSYNC
    /* Note fsync appears to change the modtime on BSD4.2 (both vax and sun).
       Disk full in NFS may be reported here.  */
    /* mib says that closing the file will try to write as fast as NFS can do
       it, and that means the fsync here is not crucial for autosave files.  */
    if (!auto_saving && fsync (desc) < 0
	/* If fsync fails with EINTR, don't treat that as serious.  */
	&& errno != EINTR)
      {
	failure = 1;
	save_errno = errno;
      }
#endif /* HAVE_FSYNC */

    /* Spurious "file has changed on disk" warnings have been
       observed on Suns as well.
       It seems that `close' can change the modtime, under nfs.

       (This has supposedly been fixed in Sunos 4,
       but who knows about all the other machines with NFS?)  */
    /* On VMS and APOLLO, must do the stat after the close
       since closing changes the modtime.  */
    /* As it does on Windows too - kkm */
    /* The spurious warnings appear on Linux too.  Rather than handling
       this on a per-system basis, unconditionally do the stat after the close - cgw */

#if 0 /* !defined (WINDOWSNT) */  /* !defined (VMS) && !defined (APOLLO) */
    fstat (desc, &st);
#endif

    /* NFS can report a write failure now.  */
    if (close (desc) < 0)
      {
	failure = 1;
	save_errno = errno;
      }

    /* Discard the close unwind-protect.  Execute the one for
       build_annotations (switches back to the original current buffer
       as necessary). */
    XCAR (desc_locative) = Qnil;
    unbind_to (speccount, Qnil);
  }

  /* # if defined (WINDOWSNT) */ /* defined (VMS) || defined (APOLLO) */
  stat ((char *) XSTRING_DATA (fn), &st);
  /* #endif */

#ifdef CLASH_DETECTION
  if (!auto_saving)
    unlock_file (lockname);
#endif /* CLASH_DETECTION */

  /* Do this before reporting IO error
     to avoid a "file has changed on disk" warning on
     next attempt to save.  */
  if (visiting)
    current_buffer->modtime = st.st_mtime;

  if (failure)
    error ("IO error writing %s: %s",
           XSTRING_DATA (fn),
           strerror (save_errno));

  if (visiting)
    {
      BUF_SAVE_MODIFF (current_buffer) = BUF_MODIFF (current_buffer);
      current_buffer->saved_size = make_int (BUF_SIZE (current_buffer));
      current_buffer->filename = visit_file;
      MARK_MODELINE_CHANGED;
    }
  else if (quietly)
    {
      return Qnil;
    }

  if (!auto_saving)
    {
      if (visiting_other)
        message ("Wrote %s", XSTRING_DATA (visit_file));
      else
	{
	  struct gcpro gcpro1;
	  Lisp_Object fsp;
	  GCPRO1 (fn);

	  fsp = Ffile_symlink_p (fn);
	  if (NILP (fsp))
	    message ("Wrote %s", XSTRING_DATA (fn));
	  else
	    message ("Wrote %s (symlink to %s)",
		     XSTRING_DATA (fn), XSTRING_DATA (fsp));
	  UNGCPRO;
	}
    }
  return Qnil;
}

/* #### This is such a load of shit!!!!  There is no way we should define
   something so stupid as a subr, just sort the fucking list more
   intelligently. */
DEFUN ("car-less-than-car", Fcar_less_than_car, 2, 2, 0, /*
Return t if (car A) is numerically less than (car B).
*/
       (a, b))
{
  Lisp_Object objs[2];
  objs[0] = Fcar (a);
  objs[1] = Fcar (b);
  return Flss (2, objs);
}

/* Heh heh heh, let's define this too, just to aggravate the person who
   wrote the above comment. */
DEFUN ("cdr-less-than-cdr", Fcdr_less_than_cdr, 2, 2, 0, /*
Return t if (cdr A) is numerically less than (cdr B).
*/
       (a, b))
{
  Lisp_Object objs[2];
  objs[0] = Fcdr (a);
  objs[1] = Fcdr (b);
  return Flss (2, objs);
}

/* Build the complete list of annotations appropriate for writing out
   the text between START and END, by calling all the functions in
   write-region-annotate-functions and merging the lists they return.
   If one of these functions switches to a different buffer, we assume
   that buffer contains altered text.  Therefore, the caller must
   make sure to restore the current buffer in all cases,
   as save-excursion would do.  */

static Lisp_Object
build_annotations (Lisp_Object start, Lisp_Object end)
{
  /* This function can GC */
  Lisp_Object annotations;
  Lisp_Object p, res;
  struct gcpro gcpro1, gcpro2;
  Lisp_Object original_buffer;

  XSETBUFFER (original_buffer, current_buffer);

  annotations = Qnil;
  p = Vwrite_region_annotate_functions;
  GCPRO2 (annotations, p);
  while (!NILP (p))
    {
      struct buffer *given_buffer = current_buffer;
      Vwrite_region_annotations_so_far = annotations;
      res = call2 (Fcar (p), start, end);
      /* If the function makes a different buffer current,
	 assume that means this buffer contains altered text to be output.
	 Reset START and END from the buffer bounds
	 and discard all previous annotations because they should have
	 been dealt with by this function.  */
      if (current_buffer != given_buffer)
	{
	  start = make_int (BUF_BEGV (current_buffer));
	  end = make_int (BUF_ZV (current_buffer));
	  annotations = Qnil;
	}
      Flength (res);     /* Check basic validity of return value */
      annotations = merge (annotations, res, Qcar_less_than_car);
      p = Fcdr (p);
    }

  /* Now do the same for annotation functions implied by the file-format */
  if (auto_saving && (!EQ (Vauto_save_file_format, Qt)))
    p = Vauto_save_file_format;
  else
    p = current_buffer->file_format;
  while (!NILP (p))
    {
      struct buffer *given_buffer = current_buffer;
      Vwrite_region_annotations_so_far = annotations;
      res = call4 (Qformat_annotate_function, Fcar (p), start, end,
		   original_buffer);
      if (current_buffer != given_buffer)
	{
	  start = make_int (BUF_BEGV (current_buffer));
	  end = make_int (BUF_ZV (current_buffer));
	  annotations = Qnil;
	}
      Flength (res);
      annotations = merge (annotations, res, Qcar_less_than_car);
      p = Fcdr (p);
    }
  UNGCPRO;
  return annotations;
}

/* Write to stream OUTSTREAM the characters from INSTREAM (it is read until
   EOF is encountered), assuming they start at position POS in the buffer
   of string that STREAM refers to.  Intersperse with them the annotations
   from *ANNOT that fall into the range of positions we are reading from,
   each at its appropriate position.

   Modify *ANNOT by discarding elements as we output them.
   The return value is negative in case of system call failure.  */

/* 4K should probably be fine.  We just need to reduce the number of
   function calls to reasonable level.  The Lstream stuff itself will
   batch to 64K to reduce the number of system calls. */

#define A_WRITE_BATCH_SIZE 4096

static int
a_write (Lisp_Object outstream, Lisp_Object instream, int pos,
	 Lisp_Object *annot)
{
  Lisp_Object tem;
  int nextpos;
  unsigned char largebuf[A_WRITE_BATCH_SIZE];
  Lstream *instr = XLSTREAM (instream);
  Lstream *outstr = XLSTREAM (outstream);

  while (LISTP (*annot))
    {
      tem = Fcar_safe (Fcar (*annot));
      if (INTP (tem))
	nextpos = XINT (tem);
      else
	nextpos = INT_MAX;
#ifdef MULE
      /* If there are annotations left and we have Mule, then we
	 have to do the I/O one emchar at a time so we can
	 determine when to insert the annotation. */
      if (!NILP (*annot))
	{
	  Emchar ch;
	  while (pos != nextpos && (ch = Lstream_get_emchar (instr)) != EOF)
	    {
	      if (Lstream_put_emchar (outstr, ch) < 0)
		return -1;
	      pos++;
	    }
	}
      else
#endif /* MULE */
	{
	  while (pos != nextpos)
	    {
	      /* Otherwise there is no point to that.  Just go in batches. */
	      int chunk = min (nextpos - pos, A_WRITE_BATCH_SIZE);

	      chunk = Lstream_read (instr, largebuf, chunk);
	      if (chunk < 0)
		return -1;
	      if (chunk == 0) /* EOF */
		break;
	      if (Lstream_write (outstr, largebuf, chunk) < chunk)
		return -1;
	      pos += chunk;
	    }
	}
      if (pos == nextpos)
	{
	  tem = Fcdr (Fcar (*annot));
	  if (STRINGP (tem))
	    {
	      if (Lstream_write (outstr, XSTRING_DATA (tem),
				 XSTRING_LENGTH (tem)) < 0)
		return -1;
	    }
	  *annot = Fcdr (*annot);
	}
      else
	return 0;
    }
  return -1;
}



#if 0
#include <des_crypt.h>

#define CRYPT_BLOCK_SIZE 8	/* bytes */
#define CRYPT_KEY_SIZE 8	/* bytes */

DEFUN ("encrypt-string", Fencrypt_string, 2, 2, 0, /*
Encrypt STRING using KEY.
*/
       (string, key))
{
  char *encrypted_string, *raw_key;
  int rounded_size, extra, key_size;

  /* !!#### May produce bogus data under Mule. */
  CHECK_STRING (string);
  CHECK_STRING (key);

  extra = XSTRING_LENGTH (string) % CRYPT_BLOCK_SIZE;
  rounded_size = XSTRING_LENGTH (string) + extra;
  encrypted_string = alloca (rounded_size + 1);
  memcpy (encrypted_string, XSTRING_DATA (string), XSTRING_LENGTH (string));
  memset (encrypted_string + rounded_size - extra, 0, extra + 1);

  key_size = min (CRYPT_KEY_SIZE, XSTRING_LENGTH (key))

  raw_key = alloca (CRYPT_KEY_SIZE + 1);
  memcpy (raw_key, XSTRING_DATA (key), key_size);
  memset (raw_key + key_size, 0, (CRYPT_KEY_SIZE + 1) - key_size);

  ecb_crypt (raw_key, encrypted_string, rounded_size,
	     DES_ENCRYPT | DES_SW);
  return make_string (encrypted_string, rounded_size);
}

DEFUN ("decrypt-string", Fdecrypt_string, 2, 2, 0, /*
Decrypt STRING using KEY.
*/
       (string, key))
{
  char *decrypted_string, *raw_key;
  int string_size, key_size;

  CHECK_STRING (string);
  CHECK_STRING (key);

  string_size = XSTRING_LENGTH (string) + 1;
  decrypted_string = alloca (string_size);
  memcpy (decrypted_string, XSTRING_DATA (string), string_size);
  decrypted_string[string_size - 1] = '\0';

  key_size = min (CRYPT_KEY_SIZE, XSTRING_LENGTH (key))

  raw_key = alloca (CRYPT_KEY_SIZE + 1);
  memcpy (raw_key, XSTRING_DATA (key), key_size);
  memset (raw_key + key_size, 0, (CRYPT_KEY_SIZE + 1) - key_size);


  ecb_crypt (raw_key, decrypted_string, string_size, D | DES_SW);
  return make_string (decrypted_string, string_size - 1);
}
#endif /* 0 */


DEFUN ("verify-visited-file-modtime", Fverify_visited_file_modtime, 1, 1, 0, /*
Return t if last mod time of BUF's visited file matches what BUF records.
This means that the file has not been changed since it was visited or saved.
*/
       (buf))
{
  /* This function can call lisp */
  struct buffer *b;
  struct stat st;
  Lisp_Object handler;

  CHECK_BUFFER (buf);
  b = XBUFFER (buf);

  if (!STRINGP (b->filename)) return Qt;
  if (b->modtime == 0) return Qt;

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

  if (stat ((char *) XSTRING_DATA (b->filename), &st) < 0)
    {
      /* If the file doesn't exist now and didn't exist before,
	 we say that it isn't modified, provided the error is a tame one.  */
      if (errno == ENOENT || errno == EACCES || errno == ENOTDIR)
	st.st_mtime = -1;
      else
	st.st_mtime = 0;
    }
  if (st.st_mtime == b->modtime
      /* If both are positive, accept them if they are off by one second.  */
      || (st.st_mtime > 0 && b->modtime > 0
	  && (st.st_mtime == b->modtime + 1
	      || st.st_mtime == b->modtime - 1)))
    return Qt;
  return Qnil;
}

DEFUN ("clear-visited-file-modtime", Fclear_visited_file_modtime, 0, 0, 0, /*
Clear out records of last mod time of visited file.
Next attempt to save will certainly not complain of a discrepancy.
*/
       ())
{
  current_buffer->modtime = 0;
  return Qnil;
}

DEFUN ("visited-file-modtime", Fvisited_file_modtime, 0, 0, 0, /*
Return the current buffer's recorded visited file modification time.
The value is a list of the form (HIGH . LOW), like the time values
that `file-attributes' returns.
*/
       ())
{
  return time_to_lisp ((time_t) current_buffer->modtime);
}

DEFUN ("set-visited-file-modtime", Fset_visited_file_modtime, 0, 1, 0, /*
Update buffer's recorded modification time from the visited file's time.
Useful if the buffer was not read from the file normally
or if the file itself has been changed for some known benign reason.
An argument specifies the modification time value to use
\(instead of that of the visited file), in the form of a list
\(HIGH . LOW) or (HIGH LOW).
*/
       (time_list))
{
  /* This function can call lisp */
  if (!NILP (time_list))
    {
      time_t the_time;
      lisp_to_time (time_list, &the_time);
      current_buffer->modtime = (int) the_time;
    }
  else
    {
      Lisp_Object filename;
      struct stat st;
      Lisp_Object handler;
      struct gcpro gcpro1, gcpro2, gcpro3;

      GCPRO3 (filename, time_list, current_buffer->filename);
      filename = Fexpand_file_name (current_buffer->filename, Qnil);

      /* If the file name has special constructs in it,
	 call the corresponding file handler.  */
      handler = Ffind_file_name_handler (filename, Qset_visited_file_modtime);
      UNGCPRO;
      if (!NILP (handler))
	/* The handler can find the file name the same way we did.  */
	return call2 (handler, Qset_visited_file_modtime, Qnil);
      else if (stat ((char *) XSTRING_DATA (filename), &st) >= 0)
	current_buffer->modtime = st.st_mtime;
    }

  return Qnil;
}

static Lisp_Object
auto_save_error (Lisp_Object condition_object, Lisp_Object ignored)
{
  /* This function can call lisp */
  if (gc_in_progress)
    return Qnil;
  /* Don't try printing an error message after everything is gone! */
  if (preparing_for_armageddon)
    return Qnil;
  clear_echo_area (selected_frame (), Qauto_saving, 1);
  Fding (Qt, Qauto_save_error, Qnil);
  message ("Auto-saving...error for %s", XSTRING_DATA (current_buffer->name));
  Fsleep_for (make_int (1));
  message ("Auto-saving...error!for %s", XSTRING_DATA (current_buffer->name));
  Fsleep_for (make_int (1));
  message ("Auto-saving...error for %s", XSTRING_DATA (current_buffer->name));
  Fsleep_for (make_int (1));
  return Qnil;
}

static Lisp_Object
auto_save_1 (Lisp_Object ignored)
{
  /* This function can call lisp */
  /* #### I think caller is protecting current_buffer? */
  struct stat st;
  Lisp_Object fn = current_buffer->filename;
  Lisp_Object a  = current_buffer->auto_save_file_name;

  if (!STRINGP (a))
    return (Qnil);

  /* Get visited file's mode to become the auto save file's mode.  */
  if (STRINGP (fn) &&
      stat ((char *) XSTRING_DATA (fn), &st) >= 0)
    /* But make sure we can overwrite it later!  */
    auto_save_mode_bits = st.st_mode | 0600;
  else
    /* default mode for auto-save files of buffers with no file is
       readable by owner only.  This may annoy some small number of
       people, but the alternative removes all privacy from email. */
    auto_save_mode_bits = 0600;

  return
    /* !!#### need to deal with this 'escape-quoted everywhere */
    Fwrite_region_internal (Qnil, Qnil, a, Qnil, Qlambda, Qnil,
#ifdef MULE
			    Qescape_quoted
#else
			    Qnil
#endif
			    );
}

static Lisp_Object
auto_save_expand_name_error (Lisp_Object condition_object, Lisp_Object ignored)
{
  /* #### this function should spew an error message about not being
     able to open the .saves file. */
  return Qnil;
}

static Lisp_Object
auto_save_expand_name (Lisp_Object name)
{
  struct gcpro gcpro1;

  /* note that caller did NOT gc protect name, so we do it. */
  /* #### dmoore - this might not be necessary, if condition_case_1
     protects it.  but I don't think it does. */
  GCPRO1 (name);
  RETURN_UNGCPRO (Fexpand_file_name (name, Qnil));
}


static Lisp_Object
do_auto_save_unwind (Lisp_Object fd)
{
  close (XINT (fd));
  return (fd);
}

static Lisp_Object
do_auto_save_unwind_2 (Lisp_Object old_auto_saving)
{
  auto_saving = XINT (old_auto_saving);
  return Qnil;
}

/* Fdo_auto_save() checks whether a GC is in progress when it is called,
   and if so, tries to avoid touching lisp objects.

   The only time that Fdo_auto_save() is called while GC is in progress
   is if we're going down, as a result of an abort() or a kill signal.
   It's fairly important that we generate autosave files in that case!
 */

DEFUN ("do-auto-save", Fdo_auto_save, 0, 2, "", /*
Auto-save all buffers that need it.
This is all buffers that have auto-saving enabled
and are changed since last auto-saved.
Auto-saving writes the buffer into a file
so that your editing is not lost if the system crashes.
This file is not the file you visited; that changes only when you save.
Normally we run the normal hook `auto-save-hook' before saving.

Non-nil first argument means do not print any message if successful.
Non-nil second argument means save only current buffer.
*/
       (no_message, current_only))
{
  /* This function can call lisp */
  struct buffer *b;
  Lisp_Object tail, buf;
  int auto_saved = 0;
  int do_handled_files;
  Lisp_Object oquit = Qnil;
  Lisp_Object listfile = Qnil;
  Lisp_Object old;
  int listdesc = -1;
  int speccount = specpdl_depth ();
  struct gcpro gcpro1, gcpro2, gcpro3;

  XSETBUFFER (old, current_buffer);
  GCPRO3 (oquit, listfile, old);
  check_quit (); /* make Vquit_flag accurate */
  /* Ordinarily don't quit within this function,
     but don't make it impossible to quit (in case we get hung in I/O).  */
  oquit = Vquit_flag;
  Vquit_flag = Qnil;

  /* No further GCPRO needed, because (when it matters) all Lisp_Object
     variables point to non-strings reached from Vbuffer_alist.  */

  if (minibuf_level != 0 || preparing_for_armageddon)
    no_message = Qt;

  run_hook (Qauto_save_hook);

  if (STRINGP (Vauto_save_list_file_name))
    listfile = condition_case_1 (Qt,
				 auto_save_expand_name,
				 Vauto_save_list_file_name,
				 auto_save_expand_name_error, Qnil);

  /* Make sure auto_saving is reset. */
  record_unwind_protect (do_auto_save_unwind_2, make_int (auto_saving));

  auto_saving = 1;

  /* First, save all files which don't have handlers.  If Emacs is
     crashing, the handlers may tweak what is causing Emacs to crash
     in the first place, and it would be a shame if Emacs failed to
     autosave perfectly ordinary files because it couldn't handle some
     ange-ftp'd file.  */
  for (do_handled_files = 0; do_handled_files < 2; do_handled_files++)
    {
      for (tail = Vbuffer_alist;
	   CONSP (tail);
	   tail = XCDR (tail))
	{
	  buf = XCDR (XCAR (tail));
	  b = XBUFFER (buf);

	  if (!NILP (current_only)
	      && b != current_buffer)
	    continue;

	  /* Don't auto-save indirect buffers.
	     The base buffer takes care of it.  */
	  if (b->base_buffer)
	    continue;

	  /* Check for auto save enabled
	     and file changed since last auto save
	     and file changed since last real save.  */
	  if (STRINGP (b->auto_save_file_name)
	      && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)
	      && b->auto_save_modified < BUF_MODIFF (b)
	      /* -1 means we've turned off autosaving for a while--see below.  */
	      && XINT (b->saved_size) >= 0
	      && (do_handled_files
		  || NILP (Ffind_file_name_handler (b->auto_save_file_name,
						    Qwrite_region))))
	    {
	      EMACS_TIME before_time, after_time;

	      EMACS_GET_TIME (before_time);
	      /* If we had a failure, don't try again for 20 minutes.  */
	      if (!preparing_for_armageddon
		  && b->auto_save_failure_time >= 0
		  && (EMACS_SECS (before_time) - b->auto_save_failure_time <
		      1200))
		continue;

	      if (!preparing_for_armageddon &&
		  (XINT (b->saved_size) * 10
		   > (BUF_Z (b) - BUF_BEG (b)) * 13)
		  /* A short file is likely to change a large fraction;
		     spare the user annoying messages.  */
		  && XINT (b->saved_size) > 5000
		  /* These messages are frequent and annoying for `*mail*'.  */
		  && !NILP (b->filename)
		  && NILP (no_message)
		  && disable_auto_save_when_buffer_shrinks)
		{
		  /* It has shrunk too much; turn off auto-saving here.
		     Unless we're about to crash, in which case auto-save it
		     anyway.
		     */
		  message
		    ("Buffer %s has shrunk a lot; auto save turned off there",
		     XSTRING_DATA (b->name));
		  /* Turn off auto-saving until there's a real save,
		     and prevent any more warnings.  */
		  b->saved_size = make_int (-1);
		  if (!gc_in_progress)
		    Fsleep_for (make_int (1));
		  continue;
		}
	      set_buffer_internal (b);
	      if (!auto_saved && NILP (no_message))
		{
		  static CONST unsigned char *msg
		    = (CONST unsigned char *) "Auto-saving...";
		  echo_area_message (selected_frame (), msg, Qnil,
				     0, strlen ((CONST char *) msg),
				     Qauto_saving);
		}

	      /* Open the auto-save list file, if necessary.
		 We only do this now so that the file only exists
		 if we actually auto-saved any files. */
	      if (!auto_saved && STRINGP (listfile) && listdesc < 0)
		{
		  listdesc = open ((char *) XSTRING_DATA (listfile),
				   O_WRONLY | O_TRUNC | O_CREAT | OPEN_BINARY,
				   CREAT_MODE);

		  /* Arrange to close that file whether or not we get
		     an error. */
		  if (listdesc >= 0)
		    record_unwind_protect (do_auto_save_unwind,
					   make_int (listdesc));
		}

	      /* Record all the buffers that we are auto-saving in
		 the special file that lists them.  For each of
		 these buffers, record visited name (if any) and
		 auto save name.  */
	      if (listdesc >= 0)
		{
		  CONST Extbyte *auto_save_file_name_ext;
		  Extcount auto_save_file_name_ext_len;

		  GET_STRING_FILENAME_DATA_ALLOCA
		    (b->auto_save_file_name,
		     auto_save_file_name_ext,
		     auto_save_file_name_ext_len);
		  if (!NILP (b->filename))
		    {
		      CONST Extbyte *filename_ext;
		      Extcount filename_ext_len;

		      GET_STRING_FILENAME_DATA_ALLOCA (b->filename,
						       filename_ext,
						       filename_ext_len);
		      write (listdesc, filename_ext, filename_ext_len);
		    }
		  write (listdesc, "\n", 1);
		  write (listdesc, auto_save_file_name_ext,
			 auto_save_file_name_ext_len);
		  write (listdesc, "\n", 1);
		}

	      /* dmoore - In a bad scenario we've set b=XBUFFER(buf)
		 based on values in Vbuffer_alist.  auto_save_1 may
		 cause lisp handlers to run.  Those handlers may kill
		 the buffer and then GC.  Since the buffer is killed,
		 it's no longer in Vbuffer_alist so it might get reaped
		 by the GC.  We also need to protect tail. */
	      /* #### There is probably a lot of other code which has
		 pointers into buffers which may get blown away by
		 handlers. */
	      {
		struct gcpro ngcpro1, ngcpro2;
		NGCPRO2 (buf, tail);
		condition_case_1 (Qt,
				  auto_save_1, Qnil,
				  auto_save_error, Qnil);
		NUNGCPRO;
	      }
	      /* Handler killed our saved current-buffer!  Pick any. */
	      if (!BUFFER_LIVE_P (XBUFFER (old)))
		XSETBUFFER (old, current_buffer);

	      set_buffer_internal (XBUFFER (old));
	      auto_saved++;

	      /* Handler killed their own buffer! */
	      if (!BUFFER_LIVE_P(b))
		continue;

	      b->auto_save_modified = BUF_MODIFF (b);
	      b->saved_size = make_int (BUF_SIZE (b));
	      EMACS_GET_TIME (after_time);
	      /* If auto-save took more than 60 seconds,
		 assume it was an NFS failure that got a timeout.  */
	      if (EMACS_SECS (after_time) - EMACS_SECS (before_time) > 60)
		b->auto_save_failure_time = EMACS_SECS (after_time);
	    }
	}
    }

  /* Prevent another auto save till enough input events come in.  */
  if (auto_saved)
    record_auto_save ();

  /* If we didn't save anything into the listfile, remove the old
     one because nothing needed to be auto-saved.  Do this afterwards
     rather than before in case we get a crash attempting to autosave
     (in that case we'd still want the old one around). */
  if (listdesc < 0 && !auto_saved && STRINGP (listfile))
    unlink ((char *) XSTRING_DATA (listfile));

  /* Show "...done" only if the echo area would otherwise be empty. */
  if (auto_saved && NILP (no_message)
      && NILP (clear_echo_area (selected_frame (), Qauto_saving, 0)))
    {
      static CONST unsigned char *msg
        = (CONST unsigned char *)"Auto-saving...done";
      echo_area_message (selected_frame (), msg, Qnil, 0,
			 strlen ((CONST char *) msg), Qauto_saving);
    }

  Vquit_flag = oquit;

  RETURN_UNGCPRO (unbind_to (speccount, Qnil));
}

DEFUN ("set-buffer-auto-saved", Fset_buffer_auto_saved, 0, 0, 0, /*
Mark current buffer as auto-saved with its current text.
No auto-save file will be written until the buffer changes again.
*/
       ())
{
  current_buffer->auto_save_modified = BUF_MODIFF (current_buffer);
  current_buffer->saved_size = make_int (BUF_SIZE (current_buffer));
  current_buffer->auto_save_failure_time = -1;
  return Qnil;
}

DEFUN ("clear-buffer-auto-save-failure", Fclear_buffer_auto_save_failure, 0, 0, 0, /*
Clear any record of a recent auto-save failure in the current buffer.
*/
       ())
{
  current_buffer->auto_save_failure_time = -1;
  return Qnil;
}

DEFUN ("recent-auto-save-p", Frecent_auto_save_p, 0, 0, 0, /*
Return t if buffer has been auto-saved since last read in or saved.
*/
       ())
{
  return (BUF_SAVE_MODIFF (current_buffer) <
	  current_buffer->auto_save_modified) ? Qt : Qnil;
}


/************************************************************************/
/*                            initialization                            */
/************************************************************************/

void
syms_of_fileio (void)
{
  defsymbol (&Qexpand_file_name, "expand-file-name");
  defsymbol (&Qfile_truename, "file-truename");
  defsymbol (&Qsubstitute_in_file_name, "substitute-in-file-name");
  defsymbol (&Qdirectory_file_name, "directory-file-name");
  defsymbol (&Qfile_name_directory, "file-name-directory");
  defsymbol (&Qfile_name_nondirectory, "file-name-nondirectory");
  defsymbol (&Qunhandled_file_name_directory, "unhandled-file-name-directory");
  defsymbol (&Qfile_name_as_directory, "file-name-as-directory");
  defsymbol (&Qcopy_file, "copy-file");
  defsymbol (&Qmake_directory_internal, "make-directory-internal");
  defsymbol (&Qdelete_directory, "delete-directory");
  defsymbol (&Qdelete_file, "delete-file");
  defsymbol (&Qrename_file, "rename-file");
  defsymbol (&Qadd_name_to_file, "add-name-to-file");
  defsymbol (&Qmake_symbolic_link, "make-symbolic-link");
  defsymbol (&Qfile_exists_p, "file-exists-p");
  defsymbol (&Qfile_executable_p, "file-executable-p");
  defsymbol (&Qfile_readable_p, "file-readable-p");
  defsymbol (&Qfile_symlink_p, "file-symlink-p");
  defsymbol (&Qfile_writable_p, "file-writable-p");
  defsymbol (&Qfile_directory_p, "file-directory-p");
  defsymbol (&Qfile_regular_p, "file-regular-p");
  defsymbol (&Qfile_accessible_directory_p, "file-accessible-directory-p");
  defsymbol (&Qfile_modes, "file-modes");
  defsymbol (&Qset_file_modes, "set-file-modes");
  defsymbol (&Qfile_newer_than_file_p, "file-newer-than-file-p");
  defsymbol (&Qinsert_file_contents, "insert-file-contents");
  defsymbol (&Qwrite_region, "write-region");
  defsymbol (&Qverify_visited_file_modtime, "verify-visited-file-modtime");
  defsymbol (&Qset_visited_file_modtime, "set-visited-file-modtime");
  defsymbol (&Qcar_less_than_car, "car-less-than-car"); /* Vomitous! */

  defsymbol (&Qauto_save_hook, "auto-save-hook");
  defsymbol (&Qauto_save_error, "auto-save-error");
  defsymbol (&Qauto_saving, "auto-saving");

  defsymbol (&Qformat_decode, "format-decode");
  defsymbol (&Qformat_annotate_function, "format-annotate-function");

  defsymbol (&Qcompute_buffer_file_truename, "compute-buffer-file-truename");
  deferror (&Qfile_error, "file-error", "File error", Qio_error);
  deferror (&Qfile_already_exists, "file-already-exists",
	    "File already exists", Qfile_error);

  DEFSUBR (Ffind_file_name_handler);

  DEFSUBR (Ffile_name_directory);
  DEFSUBR (Ffile_name_nondirectory);
  DEFSUBR (Funhandled_file_name_directory);
  DEFSUBR (Ffile_name_as_directory);
  DEFSUBR (Fdirectory_file_name);
  DEFSUBR (Fmake_temp_name);
  DEFSUBR (Fexpand_file_name);
  DEFSUBR (Ffile_truename);
  DEFSUBR (Fsubstitute_in_file_name);
  DEFSUBR (Fcopy_file);
  DEFSUBR (Fmake_directory_internal);
  DEFSUBR (Fdelete_directory);
  DEFSUBR (Fdelete_file);
  DEFSUBR (Frename_file);
  DEFSUBR (Fadd_name_to_file);
#ifdef S_IFLNK
  DEFSUBR (Fmake_symbolic_link);
#endif /* S_IFLNK */
#ifdef HPUX_NET
  DEFSUBR (Fsysnetunam);
#endif /* HPUX_NET */
  DEFSUBR (Ffile_name_absolute_p);
  DEFSUBR (Ffile_exists_p);
  DEFSUBR (Ffile_executable_p);
  DEFSUBR (Ffile_readable_p);
  DEFSUBR (Ffile_writable_p);
  DEFSUBR (Ffile_symlink_p);
  DEFSUBR (Ffile_directory_p);
  DEFSUBR (Ffile_accessible_directory_p);
  DEFSUBR (Ffile_regular_p);
  DEFSUBR (Ffile_modes);
  DEFSUBR (Fset_file_modes);
  DEFSUBR (Fset_default_file_modes);
  DEFSUBR (Fdefault_file_modes);
  DEFSUBR (Funix_sync);
  DEFSUBR (Ffile_newer_than_file_p);
  DEFSUBR (Finsert_file_contents_internal);
  DEFSUBR (Fwrite_region_internal);
  DEFSUBR (Fcar_less_than_car); /* Vomitous! */
  DEFSUBR (Fcdr_less_than_cdr); /* Yeah oh yeah bucko .... */
#if 0
  DEFSUBR (Fencrypt_string);
  DEFSUBR (Fdecrypt_string);
#endif
  DEFSUBR (Fverify_visited_file_modtime);
  DEFSUBR (Fclear_visited_file_modtime);
  DEFSUBR (Fvisited_file_modtime);
  DEFSUBR (Fset_visited_file_modtime);

  DEFSUBR (Fdo_auto_save);
  DEFSUBR (Fset_buffer_auto_saved);
  DEFSUBR (Fclear_buffer_auto_save_failure);
  DEFSUBR (Frecent_auto_save_p);
}

void
vars_of_fileio (void)
{
  DEFVAR_LISP ("auto-save-file-format", &Vauto_save_file_format /*
*Format in which to write auto-save files.
Should be a list of symbols naming formats that are defined in `format-alist'.
If it is t, which is the default, auto-save files are written in the
same format as a regular save would use.
*/ );
  Vauto_save_file_format = Qt;

  DEFVAR_LISP ("file-name-handler-alist", &Vfile_name_handler_alist /*
*Alist of elements (REGEXP . HANDLER) for file names handled specially.
If a file name matches REGEXP, then all I/O on that file is done by calling
HANDLER.

The first argument given to HANDLER is the name of the I/O primitive
to be handled; the remaining arguments are the arguments that were
passed to that primitive.  For example, if you do
    (file-exists-p FILENAME)
and FILENAME is handled by HANDLER, then HANDLER is called like this:
    (funcall HANDLER 'file-exists-p FILENAME)
The function `find-file-name-handler' checks this list for a handler
for its argument.
*/ );
  Vfile_name_handler_alist = Qnil;

  DEFVAR_LISP ("after-insert-file-functions", &Vafter_insert_file_functions /*
A list of functions to be called at the end of `insert-file-contents'.
Each is passed one argument, the number of bytes inserted.  It should return
the new byte count, and leave point the same.  If `insert-file-contents' is
intercepted by a handler from `file-name-handler-alist', that handler is
responsible for calling the after-insert-file-functions if appropriate.
*/ );
  Vafter_insert_file_functions = Qnil;

  DEFVAR_LISP ("write-region-annotate-functions",
	       &Vwrite_region_annotate_functions /*
A list of functions to be called at the start of `write-region'.
Each is passed two arguments, START and END, as for `write-region'.
It should return a list of pairs (POSITION . STRING) of strings to be
effectively inserted at the specified positions of the file being written
\(1 means to insert before the first byte written).  The POSITIONs must be
sorted into increasing order.  If there are several functions in the list,
the several lists are merged destructively.
*/ );
  Vwrite_region_annotate_functions = Qnil;

  DEFVAR_LISP ("write-region-annotations-so-far",
	       &Vwrite_region_annotations_so_far /*
When an annotation function is called, this holds the previous annotations.
These are the annotations made by other annotation functions
that were already called.  See also `write-region-annotate-functions'.
*/ );
  Vwrite_region_annotations_so_far = Qnil;

  DEFVAR_LISP ("inhibit-file-name-handlers", &Vinhibit_file_name_handlers /*
A list of file name handlers that temporarily should not be used.
This applies only to the operation `inhibit-file-name-operation'.
*/ );
  Vinhibit_file_name_handlers = Qnil;

  DEFVAR_LISP ("inhibit-file-name-operation", &Vinhibit_file_name_operation /*
The operation for which `inhibit-file-name-handlers' is applicable.
*/ );
  Vinhibit_file_name_operation = Qnil;

  DEFVAR_LISP ("auto-save-list-file-name", &Vauto_save_list_file_name /*
File name in which we write a list of all auto save file names.
*/ );
  Vauto_save_list_file_name = Qnil;

  DEFVAR_BOOL ("disable-auto-save-when-buffer-shrinks",
	       &disable_auto_save_when_buffer_shrinks /*
If non-nil, auto-saving is disabled when a buffer shrinks too much.
This is to prevent you from losing your edits if you accidentally
delete a large chunk of the buffer and don't notice it until too late.
Saving the buffer normally turns auto-save back on.
*/ );
  disable_auto_save_when_buffer_shrinks = 1;

  DEFVAR_LISP ("directory-sep-char", &Vdirectory_sep_char /*
Directory separator character for built-in functions that return file names.
The value should be either ?/ or ?\\ (any other value is treated as ?\\).
This variable affects the built-in functions only on Windows,
on other platforms, it is initialized so that Lisp code can find out
what the normal separator is.
*/ );
  Vdirectory_sep_char = make_char ('/');
}