fileio.c 189 KB
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/* File IO for GNU Emacs.
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   Copyright (C) 1985,86,87,88,93,94,95,96,97,98,99,2000, 2001
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     Free Software Foundation, Inc.
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This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */
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#include <config.h>
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#ifdef HAVE_FCNTL_H
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#include <fcntl.h>
#endif

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#include <stdio.h>
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#include <sys/types.h>
#include <sys/stat.h>
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#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

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#if !defined (S_ISLNK) && defined (S_IFLNK)
#  define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK)
#endif

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#if !defined (S_ISFIFO) && defined (S_IFIFO)
#  define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
#endif

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#if !defined (S_ISREG) && defined (S_IFREG)
#  define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#endif

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#ifdef VMS
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#include "vms-pwd.h"
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#else
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#include <pwd.h>
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#endif

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#include <ctype.h>
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#ifdef VMS
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#include "vmsdir.h"
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#include <perror.h>
#include <stddef.h>
#include <string.h>
#endif

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#include <errno.h>

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#ifndef vax11c
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#ifndef USE_CRT_DLL
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extern int errno;
#endif
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#endif
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#ifdef APOLLO
#include <sys/time.h>
#endif

#include "lisp.h"
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#include "intervals.h"
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#include "buffer.h"
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#include "charset.h"
#include "coding.h"
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#include "window.h"

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

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#ifdef MSDOS
#include "msdos.h"
#include <sys/param.h>
#if __DJGPP__ >= 2
#include <fcntl.h>
#include <string.h>
#endif
#endif

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#ifdef DOS_NT
#define CORRECT_DIR_SEPS(s) \
  do { if ('/' == DIRECTORY_SEP) dostounix_filename (s); \
       else unixtodos_filename (s); \
  } while (0)
/* On Windows, drive letters must be alphabetic - on DOS, the Netware
   redirector allows the six letters between 'Z' and 'a' as well. */
#ifdef MSDOS
#define IS_DRIVE(x) ((x) >= 'A' && (x) <= 'z')
#endif
#ifdef WINDOWSNT
#define IS_DRIVE(x) isalpha (x)
#endif
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/* 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))
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#endif

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#ifdef VMS
#include <file.h>
#include <rmsdef.h>
#include <fab.h>
#include <nam.h>
#endif

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#include "systime.h"
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#ifdef HPUX
#include <netio.h>
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#ifndef HPUX8
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#ifndef HPUX9
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#include <errnet.h>
#endif
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#endif
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#endif
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#include "commands.h"
extern int use_dialog_box;

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#ifndef O_WRONLY
#define O_WRONLY 1
#endif

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#ifndef O_RDONLY
#define O_RDONLY 0
#endif

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#ifndef S_ISLNK
#  define lstat stat
#endif

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

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

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/* Coding system for file names, or nil if none.  */
Lisp_Object Vfile_name_coding_system;

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/* Coding system for file names used only when
   Vfile_name_coding_system is nil.  */
Lisp_Object Vdefault_file_name_coding_system;

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

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

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

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/* Function to be called to decide a coding system of a reading file.  */
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Lisp_Object Vset_auto_coding_function;
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/* Functions to be called to process text properties in inserted file.  */
Lisp_Object Vafter_insert_file_functions;

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/* Function to be called to adjust buffer-file-coding-system and the
   multibyteness of the current buffer after inserting a file.  */
Lisp_Object Vafter_insert_file_adjust_coding_function;

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

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/* 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;

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

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/* Function to call to read a file name.  */
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Lisp_Object Vread_file_name_function;
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/* Current predicate used by read_file_name_internal.  */
Lisp_Object Vread_file_name_predicate;

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/* Nonzero means, when reading a filename in the minibuffer,
 start out by inserting the default directory into the minibuffer. */
int insert_default_directory;

/* On VMS, nonzero means write new files with record format stmlf.
   Zero means use var format.  */
int vms_stmlf_recfm;

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/* On NT, specifies the directory separator character, used (eg.) when
   expanding file names.  This can be bound to / or \. */
Lisp_Object Vdirectory_sep_char;

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extern Lisp_Object Vuser_login_name;

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#ifdef WINDOWSNT
extern Lisp_Object Vw32_get_true_file_attributes;
#endif

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extern int minibuf_level;

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extern int minibuffer_auto_raise;

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/* 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.  */

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static Lisp_Object Vinhibit_file_name_handlers;
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static Lisp_Object Vinhibit_file_name_operation;
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Lisp_Object Qfile_error, Qfile_already_exists, Qfile_date_error;
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Lisp_Object Qexcl;
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Lisp_Object Qfile_name_history;

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Lisp_Object Qcar_less_than_car;

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static int a_write P_ ((int, Lisp_Object, int, int,
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			Lisp_Object *, struct coding_system *));
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static int e_write P_ ((int, Lisp_Object, int, int, struct coding_system *));

242

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void
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report_file_error (string, data)
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     const char *string;
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     Lisp_Object data;
{
  Lisp_Object errstring;
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  int errorno = errno;
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  synchronize_system_messages_locale ();
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  errstring = code_convert_string_norecord (build_string (strerror (errorno)),
					    Vlocale_coding_system, 0);

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  while (1)
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    switch (errorno)
      {
      case EEXIST:
	Fsignal (Qfile_already_exists, Fcons (errstring, data));
	break;
      default:
	/* System error messages are capitalized.  Downcase the initial
	   unless it is followed by a slash.  */
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	if (SREF (errstring, 1) != '/')
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	  SSET (errstring, 0, DOWNCASE (SREF (errstring, 0)));
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	Fsignal (Qfile_error,
		 Fcons (build_string (string), Fcons (errstring, data)));
      }
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}
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Lisp_Object
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close_file_unwind (fd)
     Lisp_Object fd;
{
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  emacs_close (XFASTINT (fd));
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  return Qnil;
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}
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/* Restore point, having saved it as a marker.  */

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static Lisp_Object
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restore_point_unwind (location)
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     Lisp_Object location;
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{
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  Fgoto_char (location);
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  Fset_marker (location, Qnil, Qnil);
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  return Qnil;
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}
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290

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Lisp_Object Qexpand_file_name;
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Lisp_Object Qsubstitute_in_file_name;
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Lisp_Object Qdirectory_file_name;
Lisp_Object Qfile_name_directory;
Lisp_Object Qfile_name_nondirectory;
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Lisp_Object Qunhandled_file_name_directory;
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Lisp_Object Qfile_name_as_directory;
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Lisp_Object Qcopy_file;
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Lisp_Object Qmake_directory_internal;
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Lisp_Object Qmake_directory;
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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_writable_p;
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Lisp_Object Qfile_symlink_p;
Lisp_Object Qaccess_file;
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Lisp_Object Qfile_directory_p;
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Lisp_Object Qfile_regular_p;
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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;
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Lisp_Object Qset_visited_file_modtime;
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DEFUN ("find-file-name-handler", Ffind_file_name_handler, Sfind_file_name_handler, 2, 2, 0,
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       doc: /* 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)
     Lisp_Object filename, operation;
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{
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  /* This function must not munge the match data.  */
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  Lisp_Object chain, inhibited_handlers, result;
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  int pos = -1;
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  result = Qnil;
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  CHECK_STRING (filename);
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  if (EQ (operation, Vinhibit_file_name_operation))
    inhibited_handlers = Vinhibit_file_name_handlers;
  else
    inhibited_handlers = Qnil;
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  for (chain = Vfile_name_handler_alist; CONSP (chain);
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       chain = XCDR (chain))
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    {
      Lisp_Object elt;
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      elt = XCAR (chain);
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      if (CONSP (elt))
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	{
	  Lisp_Object string;
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	  int match_pos;
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	  string = XCAR (elt);
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	  if (STRINGP (string)
	      && (match_pos = fast_string_match (string, filename)) > pos)
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	    {
	      Lisp_Object handler, tem;

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	      handler = XCDR (elt);
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	      tem = Fmemq (handler, inhibited_handlers);
	      if (NILP (tem))
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		{
		  result = handler;
		  pos = match_pos;
		}
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	    }
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	}
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      QUIT;
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    }
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  return result;
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}

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DEFUN ("file-name-directory", Ffile_name_directory, Sfile_name_directory,
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       1, 1, 0,
       doc: /* Return the directory component in file name FILENAME.
Return nil if FILENAME does not include a directory.
Otherwise return a directory spec.
Given a Unix syntax file name, returns a string ending in slash;
on VMS, perhaps instead a string ending in `:', `]' or `>'.  */)
     (filename)
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     Lisp_Object filename;
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{
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#ifndef DOS_NT
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  register const unsigned char *beg;
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#else
  register unsigned char *beg;
#endif
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  register const unsigned char *p;
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  Lisp_Object handler;
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  CHECK_STRING (filename);
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  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
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  handler = Ffind_file_name_handler (filename, Qfile_name_directory);
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  if (!NILP (handler))
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    return call2 (handler, Qfile_name_directory, filename);
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#ifdef FILE_SYSTEM_CASE
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  filename = FILE_SYSTEM_CASE (filename);
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#endif
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  beg = SDATA (filename);
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#ifdef DOS_NT
  beg = strcpy (alloca (strlen (beg) + 1), beg);
#endif
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  p = beg + SBYTES (filename);
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  while (p != beg && !IS_DIRECTORY_SEP (p[-1])
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#ifdef VMS
	 && p[-1] != ':' && p[-1] != ']' && p[-1] != '>'
#endif /* VMS */
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#ifdef DOS_NT
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	 /* only recognise drive specifier at the beginning */
	 && !(p[-1] == ':'
	      /* handle the "/:d:foo" and "/:foo" cases correctly  */
	      && ((p == beg + 2 && !IS_DIRECTORY_SEP (*beg))
		  || (p == beg + 4 && IS_DIRECTORY_SEP (*beg))))
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#endif
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	 ) p--;

  if (p == beg)
    return Qnil;
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#ifdef DOS_NT
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  /* Expansion of "c:" to drive and default directory.  */
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  if (p[-1] == ':')
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    {
      /* MAXPATHLEN+1 is guaranteed to be enough space for getdefdir.  */
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      unsigned char *res = alloca (MAXPATHLEN + 1);
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      unsigned char *r = res;

      if (p == beg + 4 && IS_DIRECTORY_SEP (*beg) && beg[1] == ':')
	{
	  strncpy (res, beg, 2);
	  beg += 2;
	  r += 2;
	}

      if (getdefdir (toupper (*beg) - 'A' + 1, r))
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	{
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	  if (!IS_DIRECTORY_SEP (res[strlen (res) - 1]))
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	    strcat (res, "/");
	  beg = res;
	  p = beg + strlen (beg);
	}
    }
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  CORRECT_DIR_SEPS (beg);
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#endif /* DOS_NT */
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  return make_specified_string (beg, -1, p - beg, STRING_MULTIBYTE (filename));
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}

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DEFUN ("file-name-nondirectory", Ffile_name_nondirectory,
       Sfile_name_nondirectory, 1, 1, 0,
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       doc: /* Return file name FILENAME 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.  */)
     (filename)
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     Lisp_Object filename;
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{
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  register const unsigned char *beg, *p, *end;
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  Lisp_Object handler;
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  CHECK_STRING (filename);
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  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
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  handler = Ffind_file_name_handler (filename, Qfile_name_nondirectory);
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  if (!NILP (handler))
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    return call2 (handler, Qfile_name_nondirectory, filename);
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  beg = SDATA (filename);
  end = p = beg + SBYTES (filename);
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  while (p != beg && !IS_DIRECTORY_SEP (p[-1])
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#ifdef VMS
	 && p[-1] != ':' && p[-1] != ']' && p[-1] != '>'
#endif /* VMS */
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#ifdef DOS_NT
	 /* only recognise drive specifier at beginning */
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	 && !(p[-1] == ':'
	      /* handle the "/:d:foo" case correctly  */
	      && (p == beg + 2 || (p == beg + 4 && IS_DIRECTORY_SEP (*beg))))
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#endif
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	 )
    p--;
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  return make_specified_string (p, -1, end - p, STRING_MULTIBYTE (filename));
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}
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DEFUN ("unhandled-file-name-directory", Funhandled_file_name_directory,
       Sunhandled_file_name_directory, 1, 1, 0,
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       doc: /* 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)
     Lisp_Object filename;
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{
  Lisp_Object handler;

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

  return Ffile_name_directory (filename);
}

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char *
file_name_as_directory (out, in)
     char *out, *in;
{
  int size = strlen (in) - 1;

  strcpy (out, in);

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  if (size < 0)
    {
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      out[0] = '.';
      out[1] = '/';
      out[2] = 0;
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      return out;
    }

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#ifdef VMS
  /* Is it already a directory string? */
  if (in[size] == ':' || in[size] == ']' || in[size] == '>')
    return out;
  /* Is it a VMS directory file name?  If so, hack VMS syntax.  */
  else if (! index (in, '/')
	   && ((size > 3 && ! strcmp (&in[size - 3], ".DIR"))
	       || (size > 3 && ! strcmp (&in[size - 3], ".dir"))
	       || (size > 5 && (! strncmp (&in[size - 5], ".DIR", 4)
				|| ! strncmp (&in[size - 5], ".dir", 4))
		   && (in[size - 1] == '.' || in[size - 1] == ';')
		   && in[size] == '1')))
    {
      register char *p, *dot;
      char brack;

      /* x.dir -> [.x]
	 dir:x.dir --> dir:[x]
	 dir:[x]y.dir --> dir:[x.y] */
      p = in + size;
      while (p != in && *p != ':' && *p != '>' && *p != ']') p--;
      if (p != in)
	{
	  strncpy (out, in, p - in);
	  out[p - in] = '\0';
	  if (*p == ':')
	    {
	      brack = ']';
	      strcat (out, ":[");
	    }
	  else
	    {
	      brack = *p;
	      strcat (out, ".");
	    }
	  p++;
	}
      else
	{
	  brack = ']';
	  strcpy (out, "[.");
	}
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      dot = index (p, '.');
      if (dot)
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	{
	  /* blindly remove any extension */
	  size = strlen (out) + (dot - p);
	  strncat (out, p, dot - p);
	}
      else
	{
	  strcat (out, p);
	  size = strlen (out);
	}
      out[size++] = brack;
      out[size] = '\0';
    }
#else /* not VMS */
  /* For Unix syntax, Append a slash if necessary */
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  if (!IS_DIRECTORY_SEP (out[size]))
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    {
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      /* Cannot use DIRECTORY_SEP, which could have any value */
      out[size + 1] = '/';
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      out[size + 2] = '\0';
    }
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#ifdef DOS_NT
  CORRECT_DIR_SEPS (out);
#endif
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#endif /* not VMS */
  return out;
}

DEFUN ("file-name-as-directory", Ffile_name_as_directory,
       Sfile_name_as_directory, 1, 1, 0,
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       doc: /* Return a string representing the file name FILE interpreted as a directory.
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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.
On VMS, converts \"[X]FOO.DIR\" to \"[X.FOO]\", etc.  */)
     (file)
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     Lisp_Object file;
{
  char *buf;
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  Lisp_Object handler;
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  CHECK_STRING (file);
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  if (NILP (file))
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    return Qnil;
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  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
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  handler = Ffind_file_name_handler (file, Qfile_name_as_directory);
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  if (!NILP (handler))
    return call2 (handler, Qfile_name_as_directory, file);

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  buf = (char *) alloca (SBYTES (file) + 10);
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  file_name_as_directory (buf, SDATA (file));
  return make_specified_string (buf, -1, strlen (buf),
				STRING_MULTIBYTE (file));
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}

/*
 * Convert from directory name to filename.
 * On VMS:
 *       xyzzy:[mukesh.emacs] => xyzzy:[mukesh]emacs.dir.1
 *       xyzzy:[mukesh] => xyzzy:[000000]mukesh.dir.1
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 * On UNIX, it's simple: just make sure there isn't a terminating /
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 * Value is nonzero if the string output is different from the input.
 */

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int
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directory_file_name (src, dst)
     char *src, *dst;
{
  long slen;
#ifdef VMS
  long rlen;
  char * ptr, * rptr;
  char bracket;
  struct FAB fab = cc$rms_fab;
  struct NAM nam = cc$rms_nam;
  char esa[NAM$C_MAXRSS];
#endif /* VMS */

  slen = strlen (src);
#ifdef VMS
  if (! index (src, '/')
      && (src[slen - 1] == ']'
	  || src[slen - 1] == ':'
	  || src[slen - 1] == '>'))
    {
      /* VMS style - convert [x.y.z] to [x.y]z, [x] to [000000]x */
      fab.fab$l_fna = src;
      fab.fab$b_fns = slen;
      fab.fab$l_nam = &nam;
      fab.fab$l_fop = FAB$M_NAM;

      nam.nam$l_esa = esa;
      nam.nam$b_ess = sizeof esa;
      nam.nam$b_nop |= NAM$M_SYNCHK;

      /* We call SYS$PARSE to handle such things as [--] for us. */
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      if (SYS$PARSE (&fab, 0, 0) == RMS$_NORMAL)
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	{
	  slen = nam.nam$b_esl;
	  if (esa[slen - 1] == ';' && esa[slen - 2] == '.')
	    slen -= 2;
	  esa[slen] = '\0';
	  src = esa;
	}
      if (src[slen - 1] != ']' && src[slen - 1] != '>')
	{
	  /* what about when we have logical_name:???? */
	  if (src[slen - 1] == ':')
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	    {                   /* Xlate logical name and see what we get */
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	      ptr = strcpy (dst, src); /* upper case for getenv */
	      while (*ptr)
		{
		  if ('a' <= *ptr && *ptr <= 'z')
		    *ptr -= 040;
		  ptr++;
		}
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	      dst[slen - 1] = 0;        /* remove colon */
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	      if (!(src = egetenv (dst)))
		return 0;
	      /* should we jump to the beginning of this procedure?
		 Good points: allows us to use logical names that xlate
		 to Unix names,
		 Bad points: can be a problem if we just translated to a device
		 name...
		 For now, I'll punt and always expect VMS names, and hope for
		 the best! */
	      slen = strlen (src);
	      if (src[slen - 1] != ']' && src[slen - 1] != '>')
		{ /* no recursion here! */
		  strcpy (dst, src);
		  return 0;
		}
	    }
	  else
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	    {           /* not a directory spec */
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	      strcpy (dst, src);
	      return 0;
	    }
	}
      bracket = src[slen - 1];

      /* If bracket is ']' or '>', bracket - 2 is the corresponding
	 opening bracket.  */
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      ptr = index (src, bracket - 2);
      if (ptr == 0)
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	{ /* no opening bracket */
	  strcpy (dst, src);
	  return 0;
	}
      if (!(rptr = rindex (src, '.')))
	rptr = ptr;
      slen = rptr - src;
      strncpy (dst, src, slen);
      dst[slen] = '\0';
      if (*rptr == '.')
	{
	  dst[slen++] = bracket;
	  dst[slen] = '\0';
	}
      else
	{
	  /* If we have the top-level of a rooted directory (i.e. xx:[000000]),
	     then translate the device and recurse. */
	  if (dst[slen - 1] == ':'
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	      && dst[slen - 2] != ':'   /* skip decnet nodes */
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	      && strcmp (src + slen, "[000000]") == 0)
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	    {
	      dst[slen - 1] = '\0';
	      if ((ptr = egetenv (dst))
		  && (rlen = strlen (ptr) - 1) > 0
		  && (ptr[rlen] == ']' || ptr[rlen] == '>')
		  && ptr[rlen - 1] == '.')
		{
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		  char * buf = (char *) alloca (strlen (ptr) + 1);
		  strcpy (buf, ptr);
		  buf[rlen - 1] = ']';
		  buf[rlen] = '\0';
		  return directory_file_name (buf, dst);
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		}
	      else
		dst[slen - 1] = ':';
	    }
	  strcat (dst, "[000000]");
	  slen += 8;
	}
      rptr++;
      rlen = strlen (rptr) - 1;
      strncat (dst, rptr, rlen);
      dst[slen + rlen] = '\0';
      strcat (dst, ".DIR.1");
      return 1;
    }
#endif /* VMS */
  /* Process as Unix format: just remove any final slash.
     But leave "/" unchanged; do not change it to "".  */
  strcpy (dst, src);
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#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
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  if (slen > 1
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      && IS_DIRECTORY_SEP (dst[slen - 1])
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#ifdef DOS_NT
      && !IS_ANY_SEP (dst[slen - 2])
#endif
      )
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    dst[slen - 1] = 0;
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#endif
#ifdef DOS_NT
  CORRECT_DIR_SEPS (dst);
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#endif
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  return 1;
}

DEFUN ("directory-file-name", Fdirectory_file_name, Sdirectory_file_name,
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       1, 1, 0,
       doc: /* Returns the file name of the directory named DIRECTORY.
This is the name of the file that holds the data for the directory 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.
In Unix-syntax, this function just removes the final slash.
On VMS, given a VMS-syntax directory name such as \"[X.Y]\",
it returns a file name such as \"[X]Y.DIR.1\".  */)
     (directory)
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     Lisp_Object directory;
{
  char *buf;
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  Lisp_Object handler;
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  CHECK_STRING (directory);
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  if (NILP (directory))
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    return Qnil;
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  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
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  handler = Ffind_file_name_handler (directory, Qdirectory_file_name);
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  if (!NILP (handler))
    return call2 (handler, Qdirectory_file_name, directory);

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#ifdef VMS
  /* 20 extra chars is insufficient for VMS, since we might perform a
     logical name translation. an equivalence string can be up to 255
     chars long, so grab that much extra space...  - sss */
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  buf = (char *) alloca (SBYTES (directory) + 20 + 255);
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#else
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  buf = (char *) alloca (SBYTES (directory) + 20);
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#endif
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  directory_file_name (SDATA (directory), buf);
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  return make_specified_string (buf, -1, strlen (buf),
				STRING_MULTIBYTE (directory));
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}

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static char make_temp_name_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','-','_'
};
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static unsigned make_temp_name_count, make_temp_name_count_initialized_p;

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/* Value is a temporary file name starting with PREFIX, a string.
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   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
   which has no existing file.  To make this work, PREFIX should be
   an absolute file name.
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   BASE64_P non-zero means add the pid as 3 characters in base64
   encoding.  In this case, 6 characters will be added to PREFIX to
   form the file name.  Otherwise, if Emacs is running on a system
   with long file names, add the pid as a decimal number.

   This function signals an error if no unique file name could be
   generated.  */

Lisp_Object
make_temp_name (prefix, base64_p)
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     Lisp_Object prefix;
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     int base64_p;
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{
  Lisp_Object val;
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  int len;
  int pid;
  unsigned char *p, *data;
  char pidbuf[20];
  int pidlen;
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  CHECK_STRING (prefix);
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  /* 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 = (int) getpid ();

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  if (base64_p)
    {
      pidbuf[0] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[1] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[2] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidlen = 3;
    }
  else
    {
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#ifdef HAVE_LONG_FILE_NAMES
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      sprintf (pidbuf, "%d", pid);
      pidlen = strlen (pidbuf);
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#else
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      pidbuf[0] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[1] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidbuf[2] = make_temp_name_tbl[pid & 63], pid >>= 6;
      pidlen = 3;
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#endif
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    }
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  len = SCHARS (prefix);
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  val = make_uninit_string (len + 3 + pidlen);
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  data = SDATA (val);
  bcopy(SDATA (prefix), data, len);
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  p = data + len;

  bcopy (pidbuf, p, pidlen);
  p += pidlen;

  /* 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
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     afterwards.

     We don't want make-temp-name to be called while dumping,
     because then make_temp_name_count_initialized_p would get set
     and then make_temp_name_count would not be set when Emacs starts.  */

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  if (!make_temp_name_count_initialized_p)
    {
      make_temp_name_count = (unsigned) time (NULL);
      make_temp_name_count_initialized_p = 1;
    }

  while (1)
    {
      struct stat ignored;
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      unsigned num = make_temp_name_count;
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      p[0] = make_temp_name_tbl[num & 63], num >>= 6;
      p[1] = make_temp_name_tbl[num & 63], num >>= 6;
      p[2] = make_temp_name_tbl[num & 63], num >>= 6;

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

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      if (stat (data, &ignored) < 0)
	{
	  /* We want to return only if errno is ENOENT.  */
	  if (errno == ENOENT)
	    return val;
	  else
	    /* 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
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	       in looping through 225307 stat's, which is not only
	       dog-slow, but also useless since it will fallback to
	       the errow below, anyway.  */
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	    report_file_error ("Cannot create temporary name for prefix",
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			       Fcons (prefix, Qnil));
	  /* not reached */
	}
    }

  error ("Cannot create temporary name for prefix `%s'",
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	 SDATA (prefix));
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  return Qnil;
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}
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DEFUN ("make-temp-name", Fmake_temp_name, Smake_temp_name, 1, 1, 0,
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       doc: /* Generate temporary file name (string) starting with PREFIX (a string).
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
which has no existing file.  To make this work,
PREFIX should be an absolute file name.

There is a race condition between calling `make-temp-name' and creating the
file which opens all kinds of security holes.  For that reason, you should
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probably use `make-temp-file' instead, except in three circumstances:

* If you are creating the file in the user's home directory.
* If you are creating a directory rather than an ordinary file.
* If you are taking special precautions as `make-temp-file' does.  */)
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     (prefix)
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     Lisp_Object prefix;
{
  return make_temp_name (prefix, 0);
}


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DEFUN ("expand-file-name", Fexpand_file_name, Sexpand_file_name, 1, 2, 0,
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       doc: /* 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)
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     Lisp_Object name, default_directory;
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{
  unsigned char *nm;
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  register unsigned char *newdir, *p, *o;
  int tlen;
  unsigned char *target;
  struct passwd *pw;
#ifdef VMS
  unsigned char * colon = 0;
  unsigned char * close = 0;
  unsigned char * slash = 0;
  unsigned char * brack = 0;
  int lbrack = 0, rbrack = 0;
  int dots = 0;
#endif /* VMS */
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#ifdef DOS_NT
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  int drive = 0;
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  int collapse_newdir = 1;
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  int is_escaped = 0;
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#endif /* DOS_NT */
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  int length;
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  Lisp_Object handler, result;
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  CHECK_STRING (name);
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  /* If the file name has special constructs in it,
     call the corresponding file handler.  */
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  handler = Ffind_file_name_handler (name, Qexpand_file_name);
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  if (!NILP (handler))
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    return call3 (handler, Qexpand_file_name, name, default_directory);
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  /* Use the buffer's default-directory if DEFAULT_DIRECTORY is omitted.  */
  if (NILP (default_directory))
    default_directory = current_buffer->directory;
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  if (! STRINGP (default_directory))
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    {
#ifdef DOS_NT
      /* "/" is not considered a root directory on DOS_NT, so using "/"
	 here causes an infinite recursion in, e.g., the following:

            (let (default-directory)
	      (expand-file-name "a"))

	 To avoid this, we set default_directory to the root of the
	 current drive.  */
      extern char *emacs_root_dir (void);

      default_directory = build_string (emacs_root_dir ());
#else
      default_directory = build_string ("/");
#endif
    }
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  if (!NILP (default_directory))
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    {
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      handler = Ffind_file_name_handler (default_directory, Qexpand_file_name);
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      if (!NILP (handler))
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	return call3 (handler, Qexpand_file_name, name, default_directory);
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    }
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  o = SDATA (default_directory);
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  /* Make sure DEFAULT_DIRECTORY is properly expanded.
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     It would be better to do this down below where we actually use
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     default_directory.  Unfortunately, calling Fexpand_file_name recursively
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